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  • 1995-1999  (2.795)
  • Chemical Engineering  (1.635)
  • Rat  (762)
  • Computed tomography
  • 1
    ISSN: 1432-2161
    Schlagwort(e): Key words Polytomography ; Computed tomography ; Conventional tomography ; Fractures
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Objective. To compare polytomography (PT) and computed tomography (CT) for visualizing fractures and arthrodeses, with and without metal hardware, to determine whether CT could adequately replace PT. Design and patients. An ex vivo bovine model containing fractures in three planes, reduced with metal hardware, was created to compare fractures using PT and CT. The radiation dose at the skin surface was calculated for both examinations. For in vivo assessment, images of 14 patients who underwent both PT and CT (15 fractures, five arthrodeses) were coded, sorted, and independently read by four musculoskeletal radiologists. They rated the degree of certainty of their assessment. Time factors for patients and personnel and financial costs were also compared. Results. In the ex vivo model the fractures were well seen on both PT and CT. The radiation dose was higher for PT than for CT. In vivo, the degree of certainty in assessment of fractures and arthrodeses was higher for PT than CT in studies in which metal hardware was present, but there was no significant difference in studies without metal hardware or in the combined (with and without hardware) studies. The patient’s and technologist’s time required to perform a PT examination was greater than that for CT. Conclusion. In the assessment of fractures and arthrodeses containing metal hardware, PT is recommended. For studies without hardware, CT is equivalent and can replace PT.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Skeletal radiology 28 (1999), S. 632-637 
    ISSN: 1432-2161
    Schlagwort(e): Key words Scoliosis ; Computed tomography ; Three-dimensional imaging ; Spinal anomalies ; Spine surgery
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Objective. Patients with congenital vertebral anomalies frequently are afflicted with kyphoscoliosis, with the curvatures often being severe and progressive. Spinal fusion almost always is the treatment of choice in such patients. This report examines the use of three-dimensional computed tomography (3D CT) in the preoperative investigation of patients with congenital scoliosis. Design and patients. Twelve spinal CT examinations on 11 pediatric patients with congenital scoliosis underwent image processing to produce 3D images. The 3D images were compared with both the axial sections from the CT examinations and multiplanar reformations with regard to the detection of malformations liable to cause progression of scoliosis (i. e., hemivertebrae and unsegmented bars). Results and conclusions.In six of the 12 cases, the 3D images provided improved depiction of the congenital anomalies and their interrelationships compared with planar CT images. This work suggests that 3D CT can be a useful tool in the assessment of patients with congenital scoliosis.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2307
    Schlagwort(e): Key words Pyruvate kinase isoenzymes ; N-Nitrosomorpholine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The expression of the pyruvate kinase (PK) isoenzymes L and M2 was analysed in the livers of rats treated with the hepatocarcinogenic agent N-nitrosomorpholine (NNM) in the drinking water. In control animals L-PK expression was restricted to liver parenchymal cells, whereas M2-PK was detected in bile duct epithelial, blood vessel wall, endothelial and Kupffer cells. In rats treated with NNM proliferating oval cells were consistently L-PK negative and M2-PK positive, while the ductal cells of cholangiofibroses were clearly L-PK positive and coexpressed M2-PK. However, no morphological differentiation of ductal cells into hepatocyte-like cells was observed. In the clear and acidophilic cell foci storing glycogen in excess strong staining for L-PK was observed. In glycogen-poor foci induced by NNM a shift from L-PK to M2-PK expression takes place.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-5233
    Schlagwort(e): Key words Cadmium ; Diabetes ; VEP ; TBARS ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Fifty-two healthy male Swiss albino rats, aged three months, were used in this study. They were divided into four groups: control (c), diabetic (D), cadmium (Cd), and diabetic + Cd (D+Cd). A diabetic condition was induced in D and D + Cd groups by administration of alloxane (5 mg/100 g). After this treatment, Cd and D + Cd groups were injected intraperitoneally with CdCl2 (2 mg/kg week). At the end of the 2-month experimental period, flash visual evoked potentials (FVEPs) of the four groups were recorded with disk electrodes attached with electrode paste 0.5 cm in front of and behind the bregma. The mean latencies off the P1, N1, P2, N2 and P3 components were significantly prolonged in the diabetic group compared with the control group. The mean latencies of P3 in the D + Cd group and of P1 and P3 in the Cd group were longer than those of the control group. P2N2 amplitude of Cd and D + Cd groups were significantly increased compared with the control group. On the other hand, thiobarbituric acid-reactive substances (TBARS) were determined as an indicator of lipid peroxidation. Our data showed that Cd treatment and diabetic condition caused a significant increase of lipid peroxidation in kidney, brain, retina and lens.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Der Radiologe 39 (1999), S. 958-964 
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Spiral-CT ; Mehrzeilen-Spiral-CT ; Pankreaskarzinom ; Tumorstaging ; 2D-/3D-Bildgebung ; Key words Computed tomography ; Computed tomography ; helical ; Computed tomography ; technology ; Computed tomography ; thin-section ; Pancreatic neoplasms ; CT
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Purpose. Investigation of the capabilities of MSCT and its value for the staging of pancreatic carcinomas. Methods. 50 Patients with suspected pancreatic carcinoma were examined with a biphasic multislice-spiral-CT protocol: slice collimation 4×1 mm, Pitch 3.5–4 mm. After administation of 120 ml contrast medium and 50 ml NaCl with a flow rate of 3.0 ml/s the examination was started with a delay of 40 s (pancreatic phase) and 80 s (portalvenous phase). Results. Multislice spiral CT allows the examination of the whole upper abdomen with nearly isotropic data sets. This is the premise for the optimal assessment of the tumor extent in all planes, excellent demarcation of the tumor against the adjacent vessels and organs and the demarcation of small peripancreatic lymph nodes. Conclusions. Multislice spiral CT and the use of interactive multiplanar reconstructions improve the staging of pancreatic cancer.
    Notizen: Zusammenfassung Ziel unserer Untersuchungen war es, die Möglichkeiten der Mehrzeilen-Detektor-Spiral-CT und ihre Bedeutung für das Staging von Pankreastumoren zu evaluieren. Bei insgesamt 50 Patienten, bei denen der Verdacht auf ein Pankreaskarzinom bestand, wurde im Rahmen der Tumorstagings ein biphasisches hochaufgelöstes Mehrzeilen-Spiral-CT mit einer Schichtkollimation von 4×1 mm, einem Pitch von 3,5–4, 120 ml Kontrastmittel, 50 ml 0,9%NaCl-Bolus, 3,0 ml/s Fluß und einem Startdelay von durchschnittlich 40 s (Pankreasparenchymphase) und 80 s (portalvenöse Phase) durchgeführt. Die Mehrzeilen-Spiral-CT ist in der Lage die gesamte Pankreasloge und auch die angrenzenden Organe mit hoher Ortsauflösung in allen Raumebenen abzubilden. Die nahezu isotrope multiplanare Bildgebung erlaubt die vollständige Erfassung der Tumorausdehnung in allen Raumebenen und eine bessere Abgrenzung der Tumoren gegenüber dem angrenzenden Fettgewebe, den benachbarten Organen (Gefäße, Duodenum, Magen) und einen sichereren Nachweis von peripankreatischen Lymphknoten. Die Mehrzeilen-Spiral-CT und der Einsatz von interaktiven multiplanaren Rekonstruktionen verbessern nachhaltig die Bestimmung der Ausdehnung von Pankreaskarzinomen.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Lungenrundherde ; Amyloidose ; Bronchialcarcinom ; Computertomographie ; Lungenbiopsie ; Key words Lung nodule ; Amyloidosis ; Bronchial carcinoma ; Computed tomography ; Lung biopsy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary We report a rare case of pulmonary nodular amyloidosis featuring all typical morphologic alterations associated with this disease; multiple amyloidomas, calcification and cavernous transformation were present. Definite diagnosis was established histologically with CT-guided biopsy. The different types of pulmonary amyloidosis and their radiological appearances are described and discussed.
    Notizen: Zusammenfassung Wir berichten über einen seltenen Fall einer pulmonalen nodulären Amyloidose mit allen typischen Merkmalen dieser Erkrankung bei gleichzeitigem Vorliegen von multiplen Amyloidomen mit Verkalkungen und zentralen Einschmelzungen. Die definitive Diagnose wurde histologisch mit einer CT-gesteuerten Biopsie gesichert. Die verschiedenen Formen der pulmonalen Amyloidose und deren radiologische Erscheinungsbilder werden beschrieben und diskutiert.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-2307
    Schlagwort(e): Key words Medullary thyroid carcinoma ; Basement membrane ; Laminin ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Medullary thyroid carcinoma (MTC) originates from C cells, which secrete calcitonin (CT), their specific marker. C cells are located in contact with the basement membrane (BM) of the thyroid follicles, which is partly made up of the laminin-2 isoform synthesized by thyrocytes. During oncogenesis, proliferation of the C cells, invading the centre of the follicles, leads to a break in their normal contact with the BM. As specific interactions of cells with BM components, especially laminins, are important for proliferation and differentiation, we investigated the relationships of normal and neoplastic C cells with laminin in the Wag/Rij rat model of human MTC. Immunocytochemical studies showed a progressive loss of the laminin layer underlying the hyperplastic C cell nodules around the large dedifferentiated tumours. The α2, β1 and γ1 chains of the laminin-2 isoform were synthesized and secreted by rat MTC 6–23 cell cultures and the tumours induced by subcutaneous injection of these cells. In situ hybridization combined with anti-CT immunocytochemistry showed a low expression of α2 mRNA on differentiated C cells and thyrocytes, but an overexpression on immunonegative spontaneous MTC and induced intrathyroid tumours. The high level of α2 gene expression, together with tumour dedifferentiation, suggests a relationship with malignancy.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1432-2277
    Schlagwort(e): Key words Xenotransplantation ; 15-deoxyspergualin ; Guinea pig ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This study aimed to investigate the effects of 15-deoxyspergualin (DSG), tacrolimus (FK 506) and cyclosporin A (CyA), alone or in combination, on delayed xenograft rejection (DXR). We used the guinea-pig-to-C6-deficient (C6–)-PVG-rat heart transplantation model, since in this strain combination, hyperacute rejection is avoided. In C6- control rats, the guinea pig xenografts survived for 39.2 ± 6.3 h (mean ± SD). Splenectomy alone resulted in a xenograft survival of 71.8 ± 7.8 h, but the addition of CyA or FK 506 did not further improve graft survival (73.6 ± 3.0 h and 72.0 ± 17.6 h, respectively). In contrast, DSG treatment increased graft survival to a mean of 99.8 ± 9.2 h. When CyA or FK 506 was combined with DSG, no additional effects were observed (105 ± 24.3 h and 95.1 ± 5.6 h, respectively). DSG alone or in combination with FK 506 or CyA resulted in a significant reduction in the serum IgM levels and reduced the deposits of IgM and IgG in rejected grafts. However, all xenografts were still heavily infiltrated by ED1 + macrophages, regardless of the treatment used. Thus, DSG treatment resulted in moderate prolongation of xenograft survival in C6– rats. The effect seems to be related to suppression of xenoreactive antibody production. To prolong xenograft survival further, strategies that inhibit macrophage infiltration seem required.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1432-1920
    Schlagwort(e): Key words Head injury ; Epidural hematoma ; Subdural hematoma ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Our purpose was to assess the role of serial CT in recently traumatized patients with clinically stable extra-axial intracranial hematomas (EACH) and a midline shift of less than 0.5 cm. A retrospective review of 91 imaging studies in 41 patients (with 45 EACH) was done to assess the time between trauma and CT; the presence and type of skull fracture; the volume, type, and location of the EACH; the presence of associated edema and/or contusion. Over a 19-day follow-up, 11 % of the dense EACH increased in volume and 27 % decreased. An adjacent skull fracture was seen most frequently in patients with a decrease in EACH volume. Clinical data remain the key to determining the need for neurosurgical intervention in patients with EACH. Follow-up CT afforded no data which altered the medical management of these patients. However, it may be said to have alerted the clinician to an increase in the size of the EACH in 11 % of cases, which could mandate close observation of this group.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1432-1920
    Schlagwort(e): Key words Atlas ; anomalies ; Atlas ; anomalies ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report a patient with disseminated malignancy and a complex anomaly of C1 and C2 in whom CT confirmed the developmental nature of the bony abnormalities.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 93-99 
    ISSN: 1432-1920
    Schlagwort(e): Key words Aneurysms ; intracranial ; Computed tomography ; spiral ; Three-dimensional reconstruction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We describe problems encountered in our first 136 patients, with 95 aneurysms, who underwent spiral CT for investigation of possible aneurysms involving the circle of Willis and adjacent major vessels, and who had surgical and/or angiographic confirmation. There were seven false-positive cases, of which the first three could be explained by operator inexperience. There were four false negatives, all small aneurysms; two were not seen because of operator error and two were hidden by an adjacent larger aneurysm. Clip artefacts prevented diagnostic studies in six of 21 postoperative studies. One aneurysm was outside the CT field of view, being on a pericallosal artery. One basilar artery tip aneurysm was excluded from the field of the CT study because of a planning error. Inspection of the axial source images is critical if the diagnosis of small or thrombosed aneurysms is to be made. Close attention to image acquisition and computer modelling is required to reduce errors in spiral CT angiography of intracranial aneurysms.
    Materialart: Digitale Medien
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  • 12
    ISSN: 1432-1920
    Schlagwort(e): Key words Haematoma ; subdural ; chronic ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We studied the frequency of various features of the appearances on high-field MRI in symptomatic patients with chronic subdural haematomas (CSDH). The ability to predict recurrence after treatment with one burr-hole procedure using MRI was evaluated. A total of 40 patients with symptomatic CSDH underwent MRI at 1.5 T. All haematomas were evacuated within a few days of the MRI examination. Symptomatic CSDH were divided into five groups according to the MRI findings: group A (11 cases), isointense or low signal on T1- and low signal on T2-weighted images; group B (18 cases), high signal on T1- and low signal on T2-weighted images; group C (5 cases), high signal on both T1- and T2-weighting; group D (1 case), low signal on T1- and high signal on T2-weighted images; group E (5 cases), heterogeneous intensity on T1- and T2-weighting throughout the haematoma cavity. The mean interval between onset of symptoms and MRI for group A was 5.0 ± 4.1 days, which was significantly shorter than that for group B (9.4 ± 4.4 days, P 〈 0.02), group C (27.8 ± 20 days, P 〈 0.005) or group E (17.8 ± 12.2 days, P 〈 0.01). Recurrence was seen in three haematomas of group A and one of group B. Reoperation was most closely correlated with diffuse low signal on T2-weighted images but not with a multiloculated appearance. Low signal on T2 weighting was surprisingly high (72.5 %) and the age of the haematomas as estimated on the MRI correlated well with the interval between the onset of symptoms and MRI. Our findings support the causative role of recurrent bleeding in the enlargement of CSDH.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 52-54 
    ISSN: 1432-1920
    Schlagwort(e): Key words Solitary fibrous tumor ; Orbit ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report the CT findings of a solitary fibrous tumor of the orbit. The radiologic features included relatively homogeneous contrast enhancement and smooth remodelling of the bones of the orbit, findings consistent with the benign nature of this relatively rare tumor.
    Materialart: Digitale Medien
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  • 14
    ISSN: 1432-1920
    Schlagwort(e): Key words Ear ; Labyrinth ; Anticoagulants ; Haemorrhage ; Magnetic resonance imaging ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report a patient who experienced a severe vertiginous episode with bilateral tinnitus and progressive right-sided hearing loss. She had Marfan's disease and was on anticoagulant treatment. The fluid in the labyrinth gave higher signal than cerebrospinal fluid on T1-weighted images, suggesting haemorrhage. The radiological follow-up is discussed.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 175-178 
    ISSN: 1432-1920
    Schlagwort(e): Key words Infarct ; cerebral ; Computed tomography ; Magnetic resonance imaging ; diffusion-weighted
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We compared CT and MRI obtained within the first 3 h of onset of a cerebral infarct. Echo-planar diffusion-weighted MRI delineated the infarcted areas most clearly, and subtle low-density areas on CT were consistent with those shown to be abnormal by diffusion-weighted MR. The signal changes of affected areas on fast spin-echo proton-density, T2-weighted and fast FLAIR images were subtler than the low density on CT.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 188-189 
    ISSN: 1432-1920
    Schlagwort(e): Key words Cyst colloid ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We describe extremely unusual radiological characteristics in a colloid cyst of the third ventricle, where the cyst became dense and its size decreased following a cerebrospinal fluid diversion procedure. Such a course of events has been reported in colloid cysts only twice in the literature.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 144-146 
    ISSN: 1432-1920
    Schlagwort(e): Key words Hypernatraemia ; Myelinolysis ; extrapontine ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The neuroimaging findings in an infant with hypernatremic dehydration are presented. Brain parenchymal haemorrhage and extensive multiple infarcts were present in the acute stage. Follow-up CT showed bilateral, symmetrical changes presumed to indicate extrapontine myelinolysis in the thalamus and globus pallidus. MRI confirmed sparing of the pons. Only three previous cases of neuroimaging abnormalities due to hypernatraemia have been described in the radiological literature.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 322-330 
    ISSN: 1432-1912
    Schlagwort(e): Key words Blood pressure ; Endothelium ; Human ; Mesenteric artery ; Rat ; Smooth muscle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The majority of the findings concerning arterial physiology and pathophysiology originate from studies with experimental animals, while only limited information exists about the functional characteristics of human arteries. Therefore, the aim of the present work was to compare the control of vascular tone in vitro in mesenteric arterial rings of corresponding size (outer diameter 0.75–1 mm) from humans and Wistar-Kyoto rats. The relaxations to acetylcholine (ACh) were clearly less marked in the mesenteric arteries of humans when compared with rats. How-ever, when calcium ionophore A23187 was used as the vasodilator, the endothelium-mediated relaxations did not significantly differ between these species. The NO synthase inhibitor N G-nitro-l-arginine methyl ester (l-NAME) attenuated the relaxations to ACh and A23187 in both groups. The endothelium-independent relaxations to the β-adrenoceptor agonist isoprenaline and the nitric oxide (NO)-donor nitroprusside were somewhat lower in human arteries, while vasodilation induced by the K+ channel opener cromakalim was similar between humans and rats. Arterial contractile sensitivity to noradrenaline and serotonin was slightly lower in human vessels, whereas contractile sensitivity to KCl was similar between these species. The contractions induced by cumulative addition of Ca2+ with noradrenaline as the agonist were effectively inhibited in both groups by the calcium channel blocker nifedipine, the effect of which was clearly more pronounced in human arteries. In conclusion, the control of vascular tone of isolated arteries of corresponding size from humans and rats appeared to be rather similar. The most marked differences between these species were the impaired endothelium-mediated dilation to ACh and the more pronounced effect of nifedipine on the Ca2+-induced contractions in human arteries.
    Materialart: Digitale Medien
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  • 19
    ISSN: 1432-1920
    Schlagwort(e): Key words Mitochondrial diseases ; Leigh's disease ; Kearns-Sayre disease ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Mitochondrial diseases result from structural, biochemical or genetic defects of mitochondria, which contain the respiratory chain. They usually affect children and young adults. We report the CT and MRI findings in 17 patients under 14 years of age, the youngest reported to date, with various mitochondrial diseases. Although imaging studies may be normal negative in the early stages, follow-up usually shows many abnormalities, which depend on clinical status and the disease. We have recognised a spectrum of findings that can be divided into four patterns: nonspecific myelin lesions (8/17); grey-matter nuclei involvement (6/17); a leukodystrophic pattern; and calcification of the brain (1/17), although mixed forms, particularly myelin and grey-matter lesions are frequent.
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  • 20
    ISSN: 1432-1920
    Schlagwort(e): Key words Spinal subdural haematoma ; Magnetic resonance imaging ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Chronic spinal subdural haematoma is a uncommon. We describe the CT and MRI appearances of chronic spinal and intracranial subdural haematomas following minor trauma. The aetiology, pathogenesis and differential diagnosis are discussed.
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 129-133 
    ISSN: 1432-1920
    Schlagwort(e): Key words Cryptococcosi ; Acquired immunodeficiency syndrome ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract CT and MRI in one case of Cryptococcus neoformans infection showed contrast-enhancing parenchymal lesions resembling granulomata or abscesses. After an initial phase without contrast enhancement, the full extent of the lesions was visible within 2 weeks of presentation. The enhancing masses were assumed to represent intracerebral cryptococcomas. Despite evidence of massive meningeal infection on cerebrospinal fluid (CSF) examination, no radiological signs of meningitis, invasion of the Virchow-Robin spaces or ventriculitis could be demonstrated. With antimycotic treatment the contrast enhancement disappeared and cystic, partly calcified lesions remained. Recurrence of meningeal infection without radiological correlates was apparent in this stage. In a second case of proven cryptococcus meningitis, dilation of Virchow-Robin spaces or cysts in the adjacent parenchyma were the main abnormalities on MRI. Enhancing masses were not detected. These cases may represent two different reactions of the immunocompromised hosts to infection with C. neoformans: widening of the perivascular spaces as a correlate of the more typical meningeal infection and enhancing parenchymal lesions as a sign of further invasion from the CSF spaces. Enhancement of cryptococcomas, indicating an inflammatory response in the surrounding brain, is not typical in patients with impairment of immune function.
    Materialart: Digitale Medien
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  • 22
    ISSN: 1432-198X
    Schlagwort(e): Key words Hypercalciuria ; Idiopathic hypercalciuria ; Bone mineral content ; 1 ; 25-Dihydroxyvitamin D ; Furosemide ; Ammonium chloride ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The relationship between bone mineral status and hypercalciuria is controversial. The effect on bone composition of different forms of hypercalciuria was studied in female rats made hypercalciuric by 7-week administration of oral furosemide (F, n=12), intraperitoneal 1,25-dihydroxy vitamin D (VD, n=11), or oral ammonium chloride (AC, n=12). Seven untreated rats served as controls (C). Hypercalciuria (mg/100 g per 24 h, mean ±SEM) of F (4.3±0.2), VD (4.1±0.4), and AC (3.9±0.3) groups was of similar intensity (C rats 1.3±0.1, P〈0.01). Weight and length gains and serum CO2, sodium, potassium, calcium, and phosphate were no different among the four groups. Bone was studied by dual-energy X-ray absorptiometry of left tibiae. AC rats had significantly less bone area (1.505±0.018 cm2) than VD and C (1.602±0.020 and 1.587±0.019 cm2). Bone mineral content was decreased in F (0.357±0.007 g) and AC (0.362±0.006 g) compared with VD (0.407±0.008 g) and C (0.389±0.009 g) groups. Bone mineral density was different between F (0.231±0.002 g/cm2) and VD and C rats (0.254±0.004 and 0.245±0.003 g/cm2), and also between AC (0.240±0.003 cm2) and VD rats. In these rat models, hypercalciuria of renal origin (F) and hypercalciuria caused by acid load (AC) adversely impaired bone mass.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Pediatric nephrology 13 (1999), S. 800-805 
    ISSN: 1432-198X
    Schlagwort(e): Key words In situ hybridization ; Kidney development ; Nephrogenesis ; Phosphatase activity ; Serine/threonine protein phosphatase 2A ; Protein phosphorylation ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Several lines of evidence suggest that the serine/threonine protein phosphatase (PP)2A is of vital importance for cell cycle regulation, cell differentiation, and signal transduction. This prompted us to study the expression of the mRNA for PP2A catalytic isoforms α and β in the developing rat kidney using in situ hybridization histochemistry. The expression patterns of the two isoforms were strikingly similar. Both were ubiquitously expressed in early metanephric kidneys. Later in gestation they were expressed in the nephrogenic zone. Strong expression was observed on postnatal day (PN) 10. This was followed by a downregulation at PN20, i.e., when nephrogenesis is completed. The expression in the adult kidney was very weak and mainly confined to the medulla. In a phosphatase activity assay, PP2A accounted for 78% of the total serine/threonine phosphatase activity in embryonic day 15 rat kidneys. PP1 was the main contributor to the remaining activity. In conclusion, PP2A is the major serine/threonine phosphatase in fetal kidneys. The age-dependent expression pattern supports the concept that this enzyme is of particular importance during renal morphogenesis and development.
    Materialart: Digitale Medien
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Pediatric nephrology 13 (1999), S. 812-815 
    ISSN: 1432-198X
    Schlagwort(e): Key words Cystinosis ; Cysteamine ; Renal function ; Rat ; Prenatal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The safety of cysteamine after renal transplantation and during pregnancy is an important issue, since girls with cystinosis are in better health on cysteamine therapy and thus more likely to become pregnant. In the first study, cysteamine was given to pregnant rats on days 6.5–18.5 post conception in oral doses of 0, 37.5, 75, 100, and 150 mg/kg per day. The dams were sacrificed on day 20.5, the fetal kidneys removed and prepared for histological examination. In the second study, cysteamine was given to dams on days 6.5–19.5 post conception in oral doses of 0, 37.5, 50, and 75 mg/kg per day. Dams were allowed to give birth naturally and pups were given cysteamine on days 4–21 to yield the same oral doses of cysteamine given to the dam. Renal function was evaluated on day 35. Histological examination of fetal kidneys revealed no changes even in kidneys from fetuses with growth retardation and malformations. Furthermore, there were no alterations in renal function in offspring on day 35. These findings demonstrate that cysteamine therapy does not affect renal development in the rat. Further investigations will be required to prove whether cysteamine therapy has the potential to affect renal development in the human.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 723-728 
    ISSN: 1432-1920
    Schlagwort(e): Key words Skull ; Eosinophilic granuloma ; Histiocytosis Langerhans-cell ; Computed tomography ; Magnetic resonance imaging ; Scintigraphy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We reviewed the imaging of four pathologically proven calvarial eosinophil granulomas. The diameter of the lesions ranged from 13 to 40 mm; three were biconvex, but the other had a collar-stud appearance. Two lesions were in the frontal and two in the parietal bone. On bone-window CT, a bevelled edge was seen in three cases and button sequestration in one, but no sclerotic rim was shown. Although one lesion had a low-density area, the lesions were slightly denser than grey matter. They were isointense with grey or white matter on T1-weighted MRI and gave heterogeneous high signal on proton-density and T2-weighted images. All enhanced markedly, with a less strongly enhancing portion within them. A tail of dural enhancement and reactive change in the overlying galea or temporal muscle were seen in all cases.
    Materialart: Digitale Medien
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  • 26
    ISSN: 1432-1920
    Schlagwort(e): Key words Cerebral atrophy ; Computed tomography ; Interobserver agreement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To assess the interobserver variability of cerebral-atrophy measures on CT, three investigators measured the bicaudate ratio (BCR) and the sylvian-fissure ratio (SFR) on 20 CT studies of patients with ischaemic stroke. The intraclass correlation coefficient of BCR measurements was 0.82 [95 % confidence interval (CI) 0.75–0.94], and that of SFR measurements 0.69 (95 % CI 0.57–0.89). The range of pairwise-calculated Pearson correlation coefficients was smaller for measurement of the BCR (0.89–0.92) than for the SFR measurements (0.66–0.84).
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 279-282 
    ISSN: 1432-1920
    Schlagwort(e): Key words Osteoblastoma ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report a young man with low back pain suspected to have a disc protrusion. Imaging suggested a tumour of the dorsal portion of the fifth lumbar vertebral body. Operation suggested a giant-cell tumour and subsequent histology showed an osteoblastoma. All typical imaging features of osteoblastoma are demonstrated in this rather uncommon location. Contrast-enhancing bone-marrow oedema on MRI, with mild enhancement of the tumour, together with the CT appearances were the clues to the diagnosis.
    Materialart: Digitale Medien
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  • 28
    ISSN: 1432-1920
    Schlagwort(e): Key words Ankylosing spondylitis ; Cauda equina syndrome ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We present the radiological features of a 42-year-old man with long-standing inactive ankylosing spondylitis (AS), demonstrating that arachnoiditis is a cause of a cauda equina syndrome (CES) in this disease. CT showed a dorsal arachnoid diverticulum causing scalloped erosion of the laminae, and punctate and curvilinear dural calcification. MRI revealed adhesion and convergence of the cauda equina dorsally into the arachnoid pouch, causing the dural sac to appear empty canal. To the best of our knowledge, dural calcification on CT is a new finding in AS, which may be related to the CES. Our findings support the hypothesis that chronic adhesive arachnoiditis with subsequent loss of meningeal elasticity may be the main cause of CES in AS.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 591-593 
    ISSN: 1432-1920
    Schlagwort(e): Key words Adenoma pleomorphic ; Nose ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Intranasal pleomorphic adenoma is rare. We report the CT features this tumor in a 41-year-old woman who presented to us with right nasal obstruction and a 2-day history of epistaxis.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Neuroradiology 41 (1999), S. 30-34 
    ISSN: 1432-1920
    Schlagwort(e): Key words Pleomorphic xanthoastrocytoma ; Computed tomography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We describe a pleomorphic xanthoastrocytoma (PXA) in a young girl whose frontal lobe location, solid structure, dural tail and MRI signal characteristics led to a preoperative diagnosis of meningioma. PXA should be considered in differential diagnosis of tumours affecting young patients with neuroradiological characteristics suggestive of meningioma.
    Materialart: Digitale Medien
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  • 31
    ISSN: 1432-1831
    Schlagwort(e): Key wordsToxoplasma gondii ; Toxoplasmosis ; Rat ; Animal model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract There is evidence that not only the immune status, but also the genetic predisposition of certain hosts influence the clinical outcome of Toxoplasma gondii infection. By far the majority of our knowledge on genetic and immunological mechanisms involved in control of T. gondii infection has been obtained by studying mouse models, which in terms of clinical outcome of infection differ considerably from humans. Rats which show a rather similar course of infection in comparison to humans have not so far been investigated for effects of genetic differences on course of the infection. In this study we show that, like mice, different strains of rats exhibit a remarkable variation in the number of brain cysts arising from chronic infection. LEW rats seem to be highly resistant to cyst formation, in contrast to F344 rats that are susceptible. In addition, F344 rats express high numbers of γδ T cells during the acute phase of infection, whereas LEW rats express elevated but comparably low numbers of γδ T cells. The RT1 (rat MHC) haplotypes of both strains are identical in the RT1A and RT1B/D regions, which encode the restriction elements for conventional peptide antigens. Consequently, rat strain-specific differences may be useful to define MHC-independent mechanisms of resistance against T. gondii, which may also act in humans.
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Der Chirurg 70 (1999), S. 1246-1254 
    ISSN: 1433-0385
    Schlagwort(e): Key words: Blunt abdominal trauma ; Ultrasonography ; Computed tomography ; Diagnostic workup. ; Schlüsselwörter: Stumpfes Bauchtrauma ; Sonographie ; Computertomographie ; Diagnostik.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Mortalität und Morbidität des stumpfen Bauchtraumas hängen direkt von der rechtzeitigen, korrekten Diagnosestellung ab. Da in der überwiegend Zahl der Fälle Begleitverletzungen vorliegen und die Patienten häufig nicht (mehr) kommunikations- bzw. kooperationsfähig sind, ist die klinische Diagnostik unzuverlässig. Bezüglich der weiteren, bildgebenden Diagnostik wurde das praktische Vorgehen in den letzten Jahren vereinfacht und weitgehend vereinheitlicht: Initial erfolgt die Ultraschalldiagnostik des Abdomens. Bei Patienten, die aufgrund eines Blutverlusts in das Abdomen kreislaufinstabil geworden sind, kann diese Ursache immer sonographisch entdeckt und damit gleichzeitig die Indikation zur Notfalllaparotomie gestellt werden. Bei kreislaufstabilen Patienten wird zur weiteren Feindiagnostik des Abdomens bei nicht ganz eindeutigem Ultraschallbefund die computertomographische Untersuchung (CT) des Abdomens angeschlossen. Vom Nachweis direkter oder indirekter Zeichen einer Läsion hängt das weitere Vorgehen ab und kann u. a. die Angiographie (Leber, Milz, Niere, Mesenterialwurzel, V. cava), die endoskopisch-retrograde Cholangio-Pankreateographie (ERCP) (Leber, Gallenwege Pankreas) bzw. die Punktion von freier intraabdominaler Flüssigkeit umfassen, wodurch Verletzungen von Hohlorganen diagnostiziert werden können. Die heute recht zuverlässige computertomographische Diagnostik des stumpfen Bauchtraumas stellt darüberhinaus eine wesentliche Voraussetzung für die heute immer deutlichere Tendenz zur konservativen Behandlung von Parenchymläsionen beim stumpfen Bauchtrauma dar. Da die Möglichkeit der Ultraschalldiagnostik heute praktisch in jedem Versorgungskrankenhaus gegeben ist und die sonographische Diagnostik fester Bestandteil der chirurgischen Ausbildung ist, sind konkurriende Verfahren wie die diagnostische Peritoneallavage praktisch bedeutungslos geworden. Auch die diagnostische Laparoskopie hat – im Ggs. zum Perforationstrauma – keinen aktuellen Stellenwert.
    Notizen: Summary. Lethality and morbidity of blunt abdominal trauma are directly dependent on the immediately valid diagnostic work-up. Since blunt abdominal trauma usually occurs in the setting of multisystem injury and patients are no longer cooperative, clinical methods of diagnosis are unreliable. In regard to the imaging procedures, the practical approach has been simplified and standardized in the last few years. Initially, ultrasonography of the abdomen is performed. If the patient is hemodynamically unstable because of intra-abdominal loss of blood, this can be reliably detected by ultrasound and emergency laparotomy is indicated. If patients are hemodynamically stable, more sophisticated assesment of the abdomen can be achieved by computed tomography. The next step depends on direct or indirect signs of an intra-abdominal lesion. Angiography may be indicated in injuries to the liver, spleen, kidney, mesenteric root or caval vein. If lesions to the liver, biliary or pancreas are detected, ERCP may be required. Lacerations of hollow organs are identified by fine-needle aspiration of free intra-abdominal fluid. Findings on computed tomography are usually reliable enough to support a more conservative approach in the treatment of parenchymal lesions in blunt abdominal trauma. Since the facilities to perform ultrasound are provided in all emergency units and knowledge of ultrasonography is an essential part of surgical training, competitive diagnostic procedures like peritoneal lavage have completely lost their former important clinical role. Similarly, diagnostic laparoscopy is – in contrast to abdominal perforations – no longer of importance.
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  • 33
    ISSN: 1433-0385
    Schlagwort(e): Key words: Liver tumor ; Liver resection ; Computed tomography ; Three-dimensional visualization ; Preoperative planning. ; Schlüsselwörter: Lebertumoren ; Leberresektionen ; Computertomographie ; dreidimensionale Visualisierung ; präoperative Planung.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Bei Patienten mit Lebertumoren stellen Sonographie, Computertomographie (CT) und in einigen Fällen die Magnetresonanztomographie (MRT) die Grundlage für die präoperative Planung von Leberresektionen dar. Auf der Basis von CT-Untersuchungen wurde ein dreidimensionales (3-D) Visualisierungsprogramm entwickelt. In dieser Studie wurde das 3-D-Visualisierungsprogramm bei 6 Patienten mit problematischer Lokalisation von Lebertumoren zur Planung des operativen Vorgehens angewendet. Bei 5 von 6 Patienten konnte die Leberresektion – wie präoperativ am Computermodell geplant – durchgeführt werden. Die intraoperativen Befunde entsprachen den 3-D-Visualisierungen. Die 3-D-Visualisierung der Leber erlaubte eine anschauliche und interaktive Planung von Leberresektionen am Computermodell und stellte somit eine verbesserte Vorbereitung für die komplexen Leberresektionen dar.
    Notizen: Summary. Preoperative planning of liver resections in patients with liver tumors is based on sonography, computed tomography and magnetic resonance imaging. A new three-dimensional (3D) visualization program was developed based on CT data. This visualization program was used for preoperative planning in 6 patients with liver tumors in problematic intrahepatic localizations. In 5 out of 6 patients the liver resection could be performed as preoperatively planned. The intraoperative findings agreed with the 3D visualization in all these patients. 3D Visualization of the liver allowed clear and interactive planning of liver resections and improved the preparation of complex liver resections.
    Materialart: Digitale Medien
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  • 34
    ISSN: 1432-0738
    Schlagwort(e): Key words Benzene ; Benzene metabolites ; Diabetes ; Cytochrome P-450 ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Benzene is a ubiquitous environmental pollutant primarily metabolized by a cytochrome P-450 (CYP-450) isoenzyme, CYP-450 IIE1. A consistent induction of CYP450 IIE1 has been observed in both rat and human affected by diabetes mellitus. The aim of this study was to evaluate whether streptozotocin (STZ)-induced diabetes determines modifications in the metabolic pathways of benzene in rat. Benzene (100 mg/kg per day, dissolved in corn oil) was administered i.p. once a day for 5 days. Urine samples were collected every day in STZ-treated and normoglycaemic animals, treated and untreated with benzene (n = 10). Urinary levels of trans,trans-muconic acid and of phenol, catechol and hydroquinone (free and conjugated with sulphuryl and glucuronic group) were measured by high-performance liquid chromatography (HPLC). In normoglycaemic rats during the 5 days of treatment with benzene we observed a progressive and significant decrement in the urinary excretion of phenol, phenyl sulphate and glucuronide, catechol, catechol glucuronide, hydroquinone, hydroquinone glucuronide and t,t-muconic acid (P 〈 0.05). In the diabetic animals, conversely, the same metabolites showed progressively increasing urinary levels (P 〈 0.05). Catechol sulphate and hydroquinone sulphate levels were below the instrument's detection limit. In the comparison between diabetic and normoglycaemic benzene treated rats, the inter-group difference was significant (P 〈 0.05) from day 3 of treatment for t,t-muconic acid, and from day 1 for free and conjugated phenol, free and glucuronide catechol and free hydroquinone. In the normoglycaemic rat exposed to benzene the decreasing trend observed in urinary excretion of free and conjugated metabolites may be due to their capability to reduce cytochromial activity. Conversely, in the diabetic rat, urinary levels of benzene metabolites tended to increase progressively, probably due to the consistent induction of CYP-450 IIE1 observed in diabetes, which would overwhelm the inhibition of this isoenzyme caused by phenolic metabolites. Furthermore, the metabolic switch towards detoxification metabolites observed after administration of high doses of benzene is not allowed in the diabetic because of reduced glutathione-S-transferase activity. As a consequence, higher levels of hydroquinone, phenol and catechol, considered the actual metabolites responsibles for benzene toxicity, will accumulate in the diabetic rat. Extrapolating these data to human, we may thus suggest that occupational exposure to benzene of a diabetic subject poses a higher risk level, as his metabolism tends to produce and accumulate higher levels of reactive benzene catabolites.
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  • 35
    ISSN: 1432-0533
    Schlagwort(e): Key words Clomethiazole ; Rat ; Spinal cord-injury ; Neuroprotection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Clomethiazole (CMZ) has a neuroprotective effect in experimental focal and global forebrain ischemia. This neuroprotective effect may depend on its ability to enhance GABA receptor activity. We have studied the effect of pretreatment with CMZ on motor function recovery and nerve cell damage after spinal cord injury (SCI). Rats were randomized and 30 min before SCI they received a single intraperitoneal dose of CMZ (150 mg/kg) or saline. The spinal cord was injured with a 50 g (4.5 g/mm2) load, applied over the exposed dura, through a curved rectangular plate (2.2 × 5.0 mm) for 5 min at T8–9. The animals became paraplegic 1 day after injury. The rats were evaluated for recovery of hind limb motor function. All animals recovered to some extent over the observation period of 12 weeks. However, hind limb motor function was significantly better in the animals pretreated with CMZ. At 12 weeks the rats were killed and perfused/fixed for morphological investigations. Microtubule-associated protein 2 (MAP2) immunostaining was used to stain neurons and dendrites and Luxol-fast blue to stain myelinated tracts of the white matter. The injured segment of the spinal cord showed severe atrophy, distortion, cavitation and necrosis of grey and white matter. Compared to uninjured controls the transverse sectional area was reduced to 32.7 ± 4% in untreated animals but only to 38.5% ± 4.1 in CMZ-treated animals. MAP2 staining showed that, compared to uninjured controls, grey matter was reduced to 7.4 ± 2.7% in saline-treated injured animals and to 22.7 ± 5.4% in CMZ-treated rats. Our results thus show that in this model CMZ improves hind limb motor function and attenuates the morphological damage to the spinal cord.
    Materialart: Digitale Medien
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 200 (1999), S. 413-417 
    ISSN: 1432-0568
    Schlagwort(e): Key words Receptor cell ; Axon ; Vomeronasal organ ; Regeneration ; Rat ; HRP-WGA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Chemosensory neurons in the vomeronasal epithelium (vomeronasal neurons) regenerate following experimentally induced degeneration. Transection of the vomeronasal nerves leads to retrograde degeneration of vomeronasal neurons followed by replacement of the cell population. The projection of the axons of regenerated vomeronasal neurons was examined by horseradish peroxidase(HRP) histochemistry and electron microscopy. HRP-wheat germ agglutinin (WGA) was placed on the surface of the vomeronasal organ of the rat. Dense distribution of HRP-labeled fibers was observed in the vomeronasal nerve and glomerular layers in the accessory olfactory bulb (AOB) of the intact rat. At one week after transection, HRP-labeled fibers were not found in the AOB, and no labeled fibers could be observed on the medial surface of the olfactory bulb where the vomeronasal nerve traversed. Three weeks after transection, labeled fiber bundles were observed on the medial surface of the olfactory bulb in all animals. No labeled fibers were detected in the AOB. From 12 to 32 weeks after transection, projection of HRP-labeled fibers was identified in the AOB in 8 out of 26 rats (the incidence of projection was 30%). But the number of projection fibers on the operated side was much smaller than on the control side. Electron microscopy confirmed that the HRP-labeled terminals make synaptic contacts with neurons in the AOB.
    Materialart: Digitale Medien
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 200 (1999), S. 521-531 
    ISSN: 1432-0568
    Schlagwort(e): Key words Development ; Internal capsule ; Nucleus basalis ; Rat ; Thalamus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  This study defines several features of the early connections of the developmentally transient perireticular thalamic nucleus of rats. The neocortex of developing rats was injected with either DiI, biotinylated dextran, WGA-HRP (wheatgerm agglutinin conjugated-horseradish peroxidase), fluorescent latex beads or cholera toxin subunit B (CTB) and their brains were processed for tracer detection with standard methods. In general, tracer injections into various regions of the developing neocortex revealed no labelled neurones within the perireticular nucleus, although some of these tracers (WGA-HRP, dextran) labelled many of the amoeboid microglial cells that are found within this nucleus. There were, however, many retrogradely labelled neurones in a region adjacent to the perireticular nucleus, within the nucleus basalis of the basal forebrain (medial edge of globus pallidus). Their identity was confirmed as neurones of the nucleus basalis since they were all were similar in morphology and somal size to neurones that were immunoreactive to NGFr (nerve growth factor receptor), an antigen found only among neurones of the nucleus basalis and basal forebrain. Moreover, double labelling experiments revealed that most, if not all, of the cortically labelled neurones were NGFr-immunoreactive also. Thus, in conclusion, our results suggest that the perireticular nucleus does not project to the neocortex; the only neurones in the general vicinity of the perireticular nucleus that have a cortical projection form part of the nucleus basalis.
    Materialart: Digitale Medien
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 200 (1999), S. 533-540 
    ISSN: 1432-0568
    Schlagwort(e): Key words Coronary vasculogenesis ; Angiogenesis ; Coronary artery ; Development ; Rat ; Embryonic heart
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The aim of this work was to address spatiotemporal and morphologic patterns of coronary artery development in rats, based on immunohistochemical and ultrastructural studies of hearts at different stages of prenatal development. Griffonia simplicifolia I lectin and α-smooth muscle antibody were used to demonstrate endothelial cells and/or their precursors and smooth muscle cells, respectively. Ultrastructural examination was performed on ED14–16 hearts to study the morphology of the developing coronary arteries in different regions of the truncus arteriosus and adjacent myocardium. On ED14 endothelial-like cells present within the mesenchyme surrounding the outflow tract penetrated the aortic wall and the truncoconal proximal myocardium. On ED15 these penetrating cells formed vascular clusters, which were the first signs of presumptive vascular channels. Development of the coronary artery proceeded by coalescence of discontinous vascular clusters, formation of the lumen (vascular channels) and establishing a connection of the proximal part with the aorta. The second layer of cells around vascular channels (embryonic media) consisted of mesenchymal cells that were attracted to the immature vessel and were first seen on ED15. At this time no lumenized connection of the coronary artery with the aorta has been seen. After the lumenized connection of the coronary artery with the aorta had been established perivascular cells of the media started to differentiate into vascular smooth muscle, as was shown by α-smooth muscle actin-staining. Further development and differentiation of the media and adventitia proceeded distally (towards the apex).
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  • 39
    ISSN: 1432-0568
    Schlagwort(e): Key words Morphogenesis ; Histochemistry ; Lectins ; Carbohydrates ; Salivary glands ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The developmental expression of salivary glycoconjugates was investigated in the rat submandibular and sublingual glands by conventional and lectin histochemistry. By the time of the first differentiation of secretory structures, in spite of similar morphological features, a different histochemical reactivity was detected, accounting for a relevant content of neutral glycoconjugates in the submandibular gland and the occurrence of both neutral and acidic glycoconjugates in the sublingual one. The use of lectins allowed the main changes of secretory components to be noted around gestational day 18. DBA and WGA lectins seemed to act as pre- and post-natal development markers while Con A lectin was indicative of post-natal differentiation. Taken together, data from lectin histochemistry indicated the transitional occurrence of glycoconjugates, probably involved in temporally restricted functions, as well as the co-existence of different secretory components that might also reflect maturational changes of single products.
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 199 (1999), S. 265-280 
    ISSN: 1432-0568
    Schlagwort(e): Key words Cat ; Rat ; Immunocytochemistry ; NADPH-diaphorase ; Thalamus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  To gain insight into the cellular organisation of the zona incerta, we have examined the chemoarchitectonic properties of this ”uncertain zone”. The brains of Sprague-Dawley rats and common cats were processed for immunocytochemistry or NADPH-diaphorase histochemistry using standard methods. For the immunocytochemistry, antibodies to γ-aminobutyric acid (GABA), glutamic acid decarboxylase (GAD), parvalbumin, calbindin, tyrosine hydroxylase, somatostatin, serotonin and glutamate were used. Two general patterns of distribution in the zona incerta were seen. First, labelled cells were restricted largely to one of the cytoarchitectonically defined sectors of the zona incerta. For instance, GABA, GAD and parvalbumin-immunoreactive cells were found principally within the ventral sector, NADPH-diaphorase and glutamate-immunoreactive cells within the dorsal sector and tyrosine hydroxylase- and somatostatin-immunoreactive cells within the rostral sector. Second, labelled cells were scattered somewhat across all incertal sectors, with no clear region of concentration. This pattern included the calbindin- and serotonin-immunoreactive cell groups. These results indicate that the zona incerta is made up of many neurochemically distinct cell groups, some of which respect the well-defined cytoarchitectonic boundaries of the nucleus, whilst others do not. This rich neurochemical diversity in the zona incerta suggests that this nucleus may have differential effects on the different structures that it projects to.
    Materialart: Digitale Medien
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 208 (1999), S. 183-188 
    ISSN: 1431-4630
    Schlagwort(e): Key words Sulphadimidine ; Fermented sausage ; Carbon-14-labelling ; Rat ; Bound residues
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract  Sulphadimidine (SDM), a drug frequently administered to pigs, is partially converted into other compounds by processing meat to produce raw, fermented sausage. With the aid of 14C-labelled SDM, evidence was obtained that part of the radioactive matter was covalently bound to the matrix. Part of these bound residues could be released in vitro by 4 M HCl at 21  °C or by 0.024 M HCl at 37  °C. Female rats were also able to release bound SDM residues and to excrete these in their urine, in amounts approaching those obtained by treatment with 4 M HCl. Both the parent compound and its main metabolite, N 4-acetyl-SDM, were observed in the urine of rats.
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  • 42
    ISSN: 1432-0851
    Schlagwort(e): Key words Transgenic ; Rat ; EGP-2 ; GA733-2 ; Immunotherapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The human pancarcinoma-associated epithelial glycoprotein-2 (EGP-2), also known as 17-1A or Ep-CAM, is a 38-kDa transmembrane antigen, commonly used for targeted immunotherapy of carcinomas. Although strongly expressed by most carcinomas, EGP-2 is also expressed in most simple epithelia. To evaluate treatment-associated effects and side-effects on tumor and normal tissue respectively, we generated an EGP-2-expressing transgenic Wistar rat. To express the cDNA of the EGP-2 in an epithelium-specific manner, the 5′ and 3′ distal flanking regions of the human keratin 18 (K18) gene were used. EGP-2 protein expression was observed in the liver and pancreas, whereas EGP-2 mRNA could also be detected in lung, intestine, stomach and kidney tissues. In this rat, EGP-2-positive tumors can be induced by injecting a rat-derived carcinoma cell line transfected with the GA733-2 cDNA encoding EGP-2. Transgenic rats were used to study specific in vivo localization of an i.v. anti-EGP-2 monoclonal antibody, MOC31, applied i.v. Immunohistochemical analyses showed the specific localization of MOC31 in s.c. induced EGP-2-positive tumors, as well as in the liver. In contrast, in EGP-2-transgenic rats, MOC31 did not bind to EGP-2-negative tumors, the pancreas, or other normal tissues in vivo. In conclusion, an EGP-2-transgenic rat model has been generated that serves as a model to evaluate the efficacy and safety of a variety of anti-EGP-2-based immunotherapeutic modalities.
    Materialart: Digitale Medien
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  • 43
    ISSN: 1432-1084
    Schlagwort(e): Key words: Liver ; diseases ; Peliosis ; Computed tomography ; Angiography ; Magnetic resonance imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Peliosis hepatis is an uncommon liver condition characterized by blood-filled cavities. We report the CT, angiographic and MR features of a case of peliosis hepatis with no obvious etiology and spontaneously regressing hemorrhagic necrosis. Helical CT showed multiple peripheral low-density regions with foci of spontaneous high density suggesting the presence of blood component. On MR imaging, the multiple peripheral lesions were hypointense on T1-weighted and hyperdense on T2-weighted images, with bright foci on all sequences suggesting subacute blood. Angiography showed no evidence of tumor or vascular malformation; multiple nodular vascular lesions filling in the parenchymal phase and persisting in the venous phase suggested blood-filled cavities. Pathological examination showed blood-filled spaces with no endothelial lining, characteristic of the parenchymal type of peliosis. Knowledge of the imaging features of hemorrhagic necrosis due to peliosis hepatis is important since it can be responsive to antibiotic therapy. Furthermore, differentiating hemorrhagic necrosis from hepatic abscess avoids dangerous and sometimes fatal percutaneous drainage.
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 457-459 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Retroperitoneal neoplasms ; Retroperitoneal space ; Computed tomography ; Magnetic resonance imaging ; Ultrasonography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. We report a rare case of pseudomyxoma retroperitonei in a 58-year-old woman with a past history of severe appendicitis. The imaging showed a multicystic mass similar to pseudomyxoma peritonei, but the tumor was located in the retroperitoneal space.
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  • 45
    ISSN: 1432-1084
    Schlagwort(e): Key words: Computerised tomographic angiography ; Electron beam tomography ; Computed tomography ; Contrast enhancement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. The aim of this study was to evaluate the suitability of electron beam tomography (EBT) with fast continuous volume scanning for CT angiography (CTA) in chest and abdomen. An Evolution XP EBT scanner with a new software version (12.34) was used. One hundred forty images per study can be acquired in 17 s using 3-mm collimation and overlapping image reconstruction. Study protocols for five different clinical applications of EBT CTA were established and evaluated. The EBT CTA technique was performed in 155 patients. High- and homogeneous density values were achieved along the whole course of the vessels; the mean density in the aorta was 〉 240 HU. Coeliac axis, superior and inferior mesenteric artery, renal and lumbar arteries were visualised in all cases. Maximum intensity projection and shaded surface display reconstruction demonstrated the relation between aneurysm and aortic branches very well due to an excellent resolution along the z-axis. In large scan volumes overlapping image reconstruction demonstrated better resolution along the z-axis than is available with helical CT. The EBT CTA technique proved to be very well suited excellent suitability for evaluation of pulmonary vessels. Compared with helical CT, EBT CTA offers a shorter scan time, which allows higher contrast enhancement in pulmonary vessels. The identification of intraluminal emboli and mural thrombi has improved. The EBT CTA technique is a very reliable tool for evaluation of aortic disease and pulmonary vessels.
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 665-668 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Osteogenesis Imperfecta ; Complications ; Hyperplastic callus ; Computed tomography ; MR imaging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. We describe the MRI and CT findings of hyperplastic callus formation simulating a tumour of pelvis in patient with osteogenesis imperfecta tarda. Possible differential diagnoses and the impact of different imaging techniques on the correct diagnosis are discussed.
    Materialart: Digitale Medien
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 662-664 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Myositis ossificans traumatica ; Computed tomography ; Paraspinal ; Cervical
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. An unusual case of myositis ossificans traumatica lesion located in the paraspinal region is reported. Despite the contiguity of the lesion with the cervical vertebrae and ominous appearance of the biopsy material, the history of antecedent trauma and computed tomography findings allowed preoperative accurate diagnosis. To our knowledge, myositis ossificans traumatica located in the cervical paraspinal region is very rare.
    Materialart: Digitale Medien
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 693-696 
    ISSN: 1432-1084
    Schlagwort(e): Key words: MALT lymphoma ; Stomach ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade lymphoma that differs from high-grade non-Hodgkin lymphoma both clinically and histologically. The CT appearances of MALT lymphoma are described. Of 40 patients referred with biopsy-proven MALT lymphoma, only seven had not had gastrectomy or chemotherapy prior to CT examination. The CT scans of these seven cases were analysed for the degree and extent of gastric wall thickening, enlargement of abdominal and extra-abdominal lymph nodes, and presence of extranodal disease. In all patients the stomach was distended with oral contrast medium and scans performed at narrow collimation, after intravenous administration of 20 mg hyoscine butylbromide. In six patients focal thickening of the gastric wall was 1 cm or less. One patient had thickening of over 4 cm. There was no enlargement of abdominal or extra-abdominal lymph nodes or extension to adjacent organs. Thus on CT, at presentation, MALT lymphoma results in minimal gastric wall thickening, unlike high-grade non-Hodgkin lymphoma, which typically causes bulky gastric disease, nodal enlargement and extension into adjacent organs. CT is therefore of limited value in monitoring response to treatment. With disease greater than minimal thickening, transformation to a higher grade should be considered.
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 711-714 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Leiomyosarcoma ; Diagnosis ; Ultrasound ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. This article presents a case of leiomyosarcomatosis with widespread lesions involving the soft tissues and the most unlikely organs such as thyroid and salivary glands, pancreas, ligamentum teres, bladder wall, and bones without lymph node or distant metastasis. The CT and US findings of this rare phenomenon are discussed with regard to the literature.
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 728-730 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Pericardial space ; Surgery complications ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. We report a case of surgically retained pericardial sponge as a cause of paracardiac mass in a woman who had thoracotomy 3 weeks prior for replacement of mitral valve prosthesis. Computed tomography examination showed a thin-walled mass containing relatively high-density material in the central part with low-density rim at the periphery suggesting a haematoma with clot formation at first. Surgically removed mass was a retained sponge between right atrium and pericardium. Gossypiboma should be included in the differential diagnosis of an intrathoracic mass besides haematoma and abscess formation in any patient who has had previous thoracotomy.
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  • 51
    ISSN: 1432-1084
    Schlagwort(e): Key words: Magnetic resonance imaging ; Rapid imaging ; Magnetic resonance ; comparative studies ; Computed tomography ; helial technology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Purpose: To compare the value of ’push-button' singe-shot non-contrast-enhanced MRI and contrast-enhanced helical CT for detection of upper abdominal disease. Methods: In 120 patients, images obtained with non contrast-enhanced single-shot MRI (T2: double echo HASTE, and T1: turbo FLASH) and contrast-enhanced helical CT were compared. Lesions or abnormalities were divided in 8 anatomical categories (1: liver; 2: pancreatobiliary; 3: kidney/adrenal gland; 4: retroperitoneum; 5: vascular; 6: spleen; 7: gastrointestinal tract and peritoneum; 8: base of thorax) and classified as follows: 2: seen at MRI only; 1: better seen at MRI; 0: no difference; −1: better seen at CT; −2: seen at CT only. Also recorded were the 'door-to-door’ examination times. Results: Of a total of 629 abnormalities, 594 were detected at MRI (94 %) and 536 at CT (85 %). CT offered better results in two categories only: retroperitoneum (mean score: −0.68) and vascular (mean score −0.87). Mean examination times were 19 min for CT and 14.8 min for MRI. Conclusion: Unenhanced single-shot MRI is a valuable first step of a comprehensive upper abdominal MR exam and may even be the final step in many patients.
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 935-936 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Horseshoe kidney ; Inferior vena cava ; Ultrasound ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Horseshoe kidney associated with anomalous inferior vena cava is a rare congenital anomaly. Radiological demonstration of this combined anomaly is also uncommon, with only two cases of preisthmic inferior vena cava with horseshoe kidney in the imaging literature. We report a case of simultaneous horseshoe kidney and inferior vena cava lying anterior to the right renal moiety diagnosed by ultrasound and computed tomography.
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 1407-1410 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Abdomen ; Foreign bodies ; Retained sponges ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Retention of surgical sponges is rare. They cause either an aseptic reaction without significant symptoms or an exudative reaction which results in early but nonspecific symptoms. Computed tomography is very useful for recognition of retained sponges. The appearance of retained sponges is widely variable. Air trapping into a surgical sponge results in the spongiform pattern which is characteristic but unfortunately uncommon. A low-density, high-density, or complex mass is found in the majority of cases, but these patterns are not specific. Sometimes, a thin high-density capsule may be seen. Rim or internal calcification is a rare finding. Finally, a radiopaque marker is not a reliable sign. Differentiation from abscess and hematoma is sometimes difficult.
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 1556-1569 
    ISSN: 1432-1084
    Schlagwort(e): Key words: HIV ; Computed tomography ; Thorax ; Chest radiography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. A wide variety of thoracic disorders can arise in patients infected with the human immunodeficiency virus (HIV), although recent developments in the therapeutic management of AIDS patients has resulted in a changing pattern of chest disease. The use of CT in the diagnosis and management of these thoracic manifestations is discussed along with the CT appearances of the various infectious and non-infectious complications of the acquired immune deficiency syndrome (AIDS) which are commonly encountered in clinical practice.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 1625-1628 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Clear-cell chondrosarcoma ; Larynx ; Computed tomography ; Inner surface image ; Surface-rendering image
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. A case of a large low-grade mixed clear-cell and conventional chondrosarcoma of the larynx is reported involving the paraglottic space, the cricoid and thyroid cartilage and characterized by an unusual long clinical course over 22 years, although multiple recurrences occurred without developing metastases. Computed tomography suggests diagnosis by detecting calcifications and adequately demonstrates the extension of the tumor. Innersurface and surface-rendering images document the airway stenosis in all directions. The unusual feature of this case consists in the peculiar histopathological differentiation of the observed chondrosarcoma showing a large clear-cell component.
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  • 56
    ISSN: 1432-1106
    Schlagwort(e): Key words Coherence ; Entorhinal cortex ; Cortex ; Hippocampus ; Amygdala ; 192 IgG-saporin ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Changes in brain electrical activity in response to cholinergic agonists, antagonists, or excitotoxic lesions of the basal forebrain may not be reflective entirely of changes in cholinergic tone, in so far as these interventions also involve noncholinergic neurons. We examined electrocortical activity in rats following bilateral intracerebroventricular administration of 192 IgG-saporin (1.8 µg/ventricle), a selective cholinergic immunotoxin directed to the low-affinity nerve growth factor receptor p75. The immunotoxin resulted in extensive loss of choline acetyl transferase (ChAT) activity in neocortex (80%–84%) and hippocampus (93%), with relative sparing of entorhinal-piriform cortex (42%) and amygdala (28%). Electrocortical activity demonstrated modest increases in 1- to 4-Hz power, decreases in 20- to 44-Hz power, and decreases in 4- to 8-Hz intra- and interhemispheric coherence. Rhythmic slow activity (RSA) occurred robustly in toxin-treated animals during voluntary movement and in response to physostigmine, with no significant differences seen in power and peak frequency in comparison with controls. Physostigmine significantly increased intrahemispheric coherence in lesioned and intact animals, with minor increases seen in interhemispheric coherence. Our study suggests that: (1) electrocortical changes in response to selective cholinergic deafferentation are more modest than those previously reported following excitotoxic lesions; (2) changes in cholinergic tone affect primarily brain electrical transmission within, in contrast to between hemispheres; and (3) a substantial cholinergic reserve remains following administration of 192 IgG-saporin, despite dramatic losses of ChAT in cortex and hippocampus. Persistence of a cholinergically modulated RSA suggests that such activity may be mediated through cholinergic neurons which, because they lack the p75 receptor, remain unaffected by the immunotoxin.
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 126 (1999), S. 307-314 
    ISSN: 1432-1106
    Schlagwort(e): Key words Striatal dopamine depletion ; Rat ; Locomotion ; Ground reaction forces ; Gait ; Unilateral ; Kinetic ; Centre of mass
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Hemi-parkinsonian rats have preserved postural reflexes but are impaired in initiation of voluntary movements. Surprisingly, these rats can walk and run, suggesting that they can access some compensatory strategy to overcome the rigidity in their impaired limbs. The purpose of the present experiment was to investigate the locomotor compensations made by hemi-parkinsonian rats by measuring the forces exerted by the limbs on the ground throughout the stride during trotting. Rats with unilateral dopamine depletion produced by injection of 6-hydroxydopamine into the nigrostriatal bundle were trained to run back and forth in an alley for food reinforcement. Ground reaction forces were measured in three orthogonal directions using a force plate embedded in the runway. Rats were also videotaped so that limb movements were synchronized with force recordings. Although locomotion was obviously impaired, the affected limbs could support weight and provide some braking forces. In addition, the impaired hindlimb provided significant propulsive force, and a relatively large laterally directed force. Analysis of vertical movement of the centre of mass suggested that the impaired hindlimb was being used partly as a spring. The most significant abnormalities were seen during the diagonal couplet of the impaired forelimb and the unimpaired hindlimb, partly reflecting the important compensatory role of the unimpaired hindlimb. These results demonstrate that this method is useful in the analysis of hemi-parkinsonian gait and provide insights as to how rats can use an impaired limb to produce weight support and propulsion.
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 126 (1999), S. 351-358 
    ISSN: 1432-1106
    Schlagwort(e): Key words Tooth pulp ; Phrenic nerve ; Electrical stimulation ; C1 spinal neuron ; Digastric electromyogram ; Somatic receptive field ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Effects of electrical stimulation of the ipsilateral tooth pulp (TP) on C1 spinal neurons were determined in 33 anesthetized rats. One hundred and seven neurons responded to TP stimulation. In 10 rats, the activity of 18 C1 spinal neurons and the amplitude of a digastric electromyogram (dEMG, n=10) increased proportionally during the TP stimulation at an intensity of 1–3 times the threshold for jaw-opening reflex (JOR). Excitatory receptive somatic fields were examined in 61 neurons. Somatic field locations of many neurons (67.2%) involved the ipsilateral face, neck, and jaw. The activity of 45 neurons was increased by both noxious pinch and brushing hair. Of the 107 C1 spinal neurons responding to TP stimulation, 55 were tested to determine the effects of electrical stimulation of the ipsilateral phrenic nerve (PN) above the heart. Twenty-eight of 55 neurons tested were excited; no change in activity was seen for the remaining 27 neurons. The activity of six neurons increased as the intensity of PN stimulation was increased. Excitatory receptive somatic fields were determined in 28 neurons, and somatic field locations of 17 neurons (60.7%) included the ipsilateral face, neck, and jaw. Both noxious pinch and brushing hair excited all 28 neurons. These results suggest that there may be the convergence of face, neck, jaw, TP, and PN afferents on the same C1 spinal neurons in the rat.
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  • 59
    ISSN: 1432-1084
    Schlagwort(e): Key words: Ultrasonography ; Computed tomography ; Bladder diseases ; Hamartoma ; Hematuria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Bladder hamartoma is a rare benign entity with only eight cases reported in the literature thus far, and whose general imaging features have not, to our knowledge, been previously discussed. The purpose of this report is to review the literature and to discuss the imaging findings in one case of bladder hamartoma where US features were those of an inhomogeneous solid mass with an unechogenic center, which was in accordance with the CT findings of a soft tissue mass with central inhomogeneous enhancement due to central necrosis.
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    European radiology 9 (1999), S. 90-92 
    ISSN: 1432-1084
    Schlagwort(e): Key words: Portal vein thrombosis ; Septic thrombosis ; Peripancreatic abscess ; Peritoneal ligaments ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Septic thrombus formation of both the main portal vein and its intrahepatic branches were observed on CT in a patient with peripancreatic abscess. The septic thrombosis of portal vein (STPV) extended from the level of porta hepatis into the intrahepatic branches, but the portal vein and superior mesenteric vein at the level of pancreatic head were preserved with no evidence of thrombosis angiographically. The gas-containing abscess near the head of the pancreas extended toward the hepatic hilum and surrounded the portal vein and its branches on CT. It was concluded that these thrombi of portal vein branches at porta hepatis and intrahepatic branches were caused by extensions of peripancreatic abscess via the hepatoduodenal ligament and ligamentum teres. Computed tomography was useful in depicting the ligamentous spread of peripancreatic abscess resulting in STPV.
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 126 (1999), S. 501-508 
    ISSN: 1432-1106
    Schlagwort(e): Key words Spinal cord ; Wide-dynamic-range neurons ; Tail formalin ; Sciatic afferences ; Thermal stimulation ; Facilitation ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  A recent model of formalin injection in the tail induced a facilitation of the hindpaw withdrawal reflexes. In the present work we tried, after injecting formalin into the tail of the albino rat, to determine the spontaneous activity and response changes of lumbar sciatic wide-dynamic-range neurons to thermal stimulations of the paw at 45°C and 48°C (the respective thresholds for noxious and non-noxious thermal stimuli). The experiments were carried out with multiple recording electrodes placed in a comb array in the lumbar segments of the spinal cord at L4–L6 level in the sciatic projection field. A significant facilitation of the spontaneous activity was already evident 2 min after injection; at 5 min there were strong facilitations to the thermal stimuli. Stimuli at 45°C, often ineffective prior to the formalin injection, became strongly excitatory. Stimuli at 48°C evoked more conspicuous responses. This facilitatory effect on spontaneous and thermal responses followed a time-course comparable to that described for the excitations seen after paw formalin injection, but the duration was more prolonged, lasting more than 2 h. These data indicate a facilitatory role of the formalin effects on spinal sciatic neurons after injection in the tail. It is proposed that the mutual effects of spinal neurons in distant spinal segments could explain the facilitation and such a time-course, and that a role in the development of prolonged pain could be envisaged.
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  • 62
    ISSN: 1432-1106
    Schlagwort(e): Key words Spatial function ; Water maze ; Procedural learning ; Cerebellum ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Recently, we demonstrated the prevalent role of cerebellar networks in the acquisition of the procedural components of spatial information by testing hemicerebellectomized (HCbed) rats in a classical spatial task, the Morris water maze (MWM). As procedures used in the water maze are a mixture of different components (that is, general procedures, exploration procedures, direct reaching procedures), for optimally solving a spatial task all procedural components must be opportunely managed. Thus, severely impaired procedural learning of cerebellar origin can be better comprehended by fractionating the procedural facets. To this aim, a two-step water-maze paradigm was employed. Normal rats were first trained to search for a hidden platform moved to a different position in each trial, utilizing a water maze setting in which visual cues were abolished by heavy black curtains surrounding the tank. In this paradigm, normal animals solved the task by using general and exploration procedures, but they could not use direct reaching skills. A subgroup of these pretrained animals was then HCbed and, after recovery from cerebellar lesion, was tested in a water maze with normal environmental cues available, a paradigm in which normal animals develop abilities for reaching the target with very direct trajectories. Pretrained HCbed animals, however, did not display the typical spatial deficits of naive HCbed rats, persisted in exhibiting the scanning strategy learned during pretraining, and never displayed direct reaching skills. In conclusion, cerebellar networks appear to be involved in the acquisition of all procedural facets necessary for shifting behavior within the maze until direct reaching of the platform. The lack of flexibility in changing exploration strategies displayed by pretrained HCbed rats is interpreted by taking into account the well-known cerebellar frontal interplay sculpting a specific cerebellar role in the acquisition of spatial procedural steps.
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  • 63
    ISSN: 1432-1084
    Schlagwort(e): Key words: Lung cancer ; Bronchioloalveolar carcinoma ; Radiolucencies ; Computed tomography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Bronchioloalveolar carcinoma (BAC) is a polymorphic lung cancer the incidence of which is rising. The presence of intratumoral radiolucencies is an important feature of bronchioloalveolar carcinoma.The aim of this study was to present pictorially the spectrum of intratumoral radiolucencies visible in BAC. In 57 BACs studied with thin-slice CT, we identified six types of radiolucencies: (a) patent intratumoral bronchioles (air bronchiologram); (b) pseudocavitations; (c) cavitation; (d) serpentine radiolucencies; (e) internal alveologram; and (f) multiple cystic lesions.
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  • 64
    ISSN: 1432-1106
    Schlagwort(e): Key words Protein lateral mobility ; Plasma membrane of brain cells ; Fluorescence recovery after photobleaching ; Concanavalin-A-receptors ; Concanavalin-A-fluorescein conjugate ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  A new method has been developed for ex vivo preparation of brain cortical cells of BN/BiRijHsd rats to make them suitable for the measurement of the lateral diffusion coefficient of the membrane components by means of fluorescence recovery after photobleaching (FRAP). The method involves chopping the brain cortex into pieces of less than 1 mm. These parts are stained with a fluorescent label (e.g., concanavalin-A-fluorescein, Con-A-FL conjugate) and then gently pressed onto a microscope slide using the coverslip. In the resulting specimen, the largest cells of the cortex can be recognized in phase-contrast image, sufficiently stained by the label and ready for the FRAP measurement. The lateral diffusion coefficient of Con-A-receptor proteins (D p) was measured in such brain cell preparations of 15 female rats in four age groups (5.6–31.8 months) and 11 males in three age groups (13.8–31.8 months). Highly significant negative, linear age correlation of D p (R=−0.9958 in females, and −0.9956 in males) were found, the regression equations being D p,=(8.8311–0.1425 X)−10 and D p█=(9.3240−0.1630 X)−10 cm2/s, respectively, where X is age in months. The data confirm that the lateral mobility of plasma membrane proteins represents an important biomarker of cellular aging in the brain cortical cells of BN/BiRijHsd rats.
    Materialart: Digitale Medien
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  • 65
    ISSN: 1432-1106
    Schlagwort(e): Key words Suprathreshold heat pain ; Adapting temperature ; Temporal parameters ; Spinal dorsal horn neuron ; Descending control ; Rat ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The influence of stimulus temperature rise rate (2.5ºC/s, 5.0ºC/s, and 10.0ºC/s), adapting (baseline) temperature (25ºC, 30ºC, and 35ºC), and duration of peak stimulus temperature (1.0 s, 2.5 s, 5.0 s, and 10.0 s) on responses evoked by noxious heat stimuli of suprathreshold intensity was studied in wide dynamic range (WDR) neurons of the rat spinal dorsal horn. The spinal neuronal responses were compared with human psychophysical data obtained using the same stimuli. Noxious heat stimuli with a peak temperature of 54ºC were applied with a contact thermostimulator to the glabrous skin of the hindfoot in rats or to the palmar skin in humans. With the highest ramp rate and the highest adapting temperature, the sensory and spinal neuronal response latencies were decreased more than expected on the basis of the change in physical parameters of the stimulus. The magnitudes of sensory and spinal neuronal response were independent of the stimulus ramp rate, whereas pain magnitude estimates and spinal neuronal impulse counts evoked by the same peak stimulus temperature were increased with an increase in the adapting stimulus temperature. The onset latencies of pain reactions and spinal neuronal responses were independent of the peak stimulus duration, whereas the latency of the maximum discharge in spinal neurons increased with prolongation of the peak stimulus. The sensory magnitude estimate of pain and the neuronal impulse count were increased with increase in stimulus duration. Following spinalization, the spinal neuronal responses were stronger and the stimulus duration-dependent increase in the impulse count developed faster. Moreover, the peak frequency of spinal neuronal response increased significantly with prolongation of the heat stimuli after spinalization, but not in animals with an intact spinal cord. The results indicate that stimulus rise rate, stimulus duration, and the adapting temperature are important factors in determining the sensory and spinal neuronal responses to high-intensity heat stimuli. The changes in the total impulse counts evoked by varying supraliminal heat stimuli in spinal dorsal horn WDR neurons corresponded well with the changes in pain magnitude estimates in humans. Also, the changes in spinal neuronal response onset latencies were accompanied by corresponding changes in onset latencies of human pain reactions but not with pain magnitude estimates. The effect of spinalization indicated that descending pathways control not only the response magnitude in the spinal dorsal horn WDR neurons but also the temporal characteristics of the spinal neuronal response.
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 128 (1999), S. 309-314 
    ISSN: 1432-1106
    Schlagwort(e): Key words GABA ; Bromodeoxyuridine ; Proliferation ; Immunohistochemistry ; Retina ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The birthdates of GABAergic amacrine cells in the rat retina were investigated by immunocytochemistry using anti-GABA and anti-bromodeoxyuridine (BrdU) antisera. The ratio of co-localization of GABA to BrdU increased gradually from embryonic-day 13 (E13) and showed a peak value on E18 in the central retina and on E20 in the periphery. After birth, until postnatal-day 3 (P3), a few co-localized cells were observed in the inner nuclear layer (INL). However, in the peripheral retina, co-localized cells were observed in the INL and ganglion cell layer until P5. Our results suggest that the birthdates of GABA-immunoreactive cells vary, depending on cell-type and that there is a temporal lag in the GABA-immunoreactive cell production in the peripheral retina relative to the central retina.
    Materialart: Digitale Medien
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  • 67
    ISSN: 1432-1106
    Schlagwort(e): Key words Learning and memory ; Electrical stimulation ; Parafascicular thalamic nucleus ; Two-way active avoidance ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  To evaluate whether electrical stimulation of the parafascicular nucleus (PF) can improve short-term (24 h) and/or long-term (21 days) retention of two-way active avoidance, rats were implanted with an electrode at this nucleus (experimental groups) or above it (control groups). After a single 30-trial acquisition session, experimental groups were submitted to a 10-min session of electrical stimulation. Results showed that the simple implantation of an electrode at the posterior PF enhanced by itself the acquisition of two-way active avoidance, in such a way that the subsequent stimulation of this region may have been unable to further improve the performance of the rats. On the other hand, parafascicular stimulation improved the 24-h retention of the task in a site-specific way, since this effect was mainly seen after stimulation of the central PF region. The facilitative effect on 24-h retention could also depend on the level of performance achieved during the acquisition session, because this improvement was only evidenced in poorly learning animals. No effects were found on 21-day retention. The present results confirm the involvement of the PF in learning and memory and the functional heterogeneity of this nucleus.
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  • 68
    ISSN: 1432-1106
    Schlagwort(e): Key words Opioids ; µ-Receptors ; κ-Receptors ; Aversion ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We studied the effects of morphine injected either systemically or into the dorsal periaqueductal gray (DPAG) or nucleus accumbens (NA) using conventional and ethological analyses of behavior of rats submitted to the elevated plus-maze test with transparent walls. Intraperitoneal morphine (0.1 mg/kg and 0.3 mg/kg) increased both standard and ethological measures, expressing general exploratory activity such as total arm entries, end-exploration, scanning, head-dipping, and rearing. Morphine 10 (7.6 µg/µl) and 30 nmol (23 µg/µl) injected into nucleus accumbens produced similar effects, which were blocked by i.p. naltrexone (2.0 mg/kg), an opioid antagonist with good affinity for µ-opioid receptors. Morphine injected into the DPAG produced either antiaversive (10 nmol) or aversive effects (30 nmol), which respectively reduced and increased entries and time spent in the open arms and behaviors associated with risk assessment (peeping out, stretched attend postures, and flat back approach). The proaversive effects were inhibited by i.p. norbinaltorphimine (2.0 mg/kg), a selective inhibitor for κ-opioid receptors. These findings support the contention that at least some of the motivational effects of morphine may be due to activation of opioid mechanisms in nucleus accumbens, and DPAG has neural substrates for antiaversive and aversive effects of morphine. Moreover, on the basis of previous and present data obtained in this laboratory, it is suggested that stimulation of µ-opioid receptors inhibits and stimulation of κ-receptors activates the neural substrate of aversion in the DPAG. On the other hand, the increase in exploratory behavior due to interaction of morphine with µ-opioid receptors in the nucleus accumbens may be due to the stimulation of the interface between neural substrates of motivation and motor output in this structure.
    Materialart: Digitale Medien
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  • 69
    ISSN: 1432-1106
    Schlagwort(e): Key words Acetylcholine ; Brain slices ; Cerebral cortex ; Long-term depression ; Rat ; Synaptic plasticity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The ability of layer I activation to facilitate the induction of long-term potentiation (LTP) in layer II/III horizontal connections of motor cortex (MI) was examined in rat brain slice preparations. Field potentials evoked in layer I and layer II/III horizontal pathways were recorded from radially aligned MI sites. While theta burst stimulation (TBS) of layer II/III pathways alone failed to induce LTP, simultaneous TBS of layer I and layer II/III inputs on alternate sides of the recording electrodes induced LTP in the layer II/III input in 8 out of 13 slices (mean change +20±6%; N=13). In the same cases, the layer I connections showed mixed effects: LTP in three cases, LTD in five cases, and no modification in five slices. Despite the facilitatory effect of layer I activation on layer II/III LTP induction, we found that the critical circuitry for this effect was outside layer I. Cutting the layer I fibers selectively in the slice did not prevent layer II/III LTP induction, while cuts preserving only layer I blocked layer II/III LTP after conjoint I+II/III TBS. Cholinergic fibers were evaluated as candidates for the facilitatory effect because they branch widely in both layers and they are thought to participate in synaptic modification. The cholinergic contribution to layer II/III LTP facilitation was investigated using bath application of muscarinic antagonists. Muscarinic blockade prevented facilitation of layer II/III LTP by layer I coactivation. Instead, conjoint stimulation in 10 µM atropine produced long-term depression (LTD) of layer II/III (–18±9%; N=11) as well as of layer I (–21±6%; N=11) horizontal responses. These results indicate that connections formed within layer I are ineffective in promoting LTP in the deeper-lying horizontal connections; the critical route by which layer I stimulation influenced LTP induction required the circuitry in the deeper layers, particularly the cholinergic system. Thus, it appears that diffuse cholinergic afferents provide an additional route to regulate activity-dependent synaptic modificaton in horizontal cortical connections.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 127 (1999), S. 298-306 
    ISSN: 1432-1106
    Schlagwort(e): Key words Motor unit ; Contraction ; Stimulation pattern ; Rat ; Medial gastrocnemius
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The effects of irregularity in the pattern of stimulation on the tension produced by motor units in the rat medial gastrocnemius muscle were investigated. The effects of decreasing as well as increasing the interpulse intervals were observed for each motor unit in tetani fused to different degrees. For each motor-unit type, it was found that the effects of these changes depended on the extent of tetanic fusion. Decreasing the interpulse interval produced an increase in tension during the tetanus: the more fused the profile of tetanus, the smaller the tension increase. Increasing the interpulse interval resulted in a decrease in tetanic tension. This effect was most prominent when the tetanic fusion index was approximately 0.75. This phenomenon resulted from the prolongation in relaxation when tetanic fusion increased, thereby preventing a decrease in tension when the interpulse interval increased. We also investigated the effects of introducing a short interpulse interval (”doublet”) at the beginning of the stimulation. The doublets produced increased tetanic tension with a more fused profile. However, the doublet enhanced the sensitivity of the tetanus to increases in interpulse interval and decreased its sensitivity to decreases in interpulse intervals. Slow-twitch motor units appeared to be significantly less sensitive to both increases and decreases in interpulse interval than fast-twitch units. This suggests that slow-twitch units are better suited for producing long-lasting contractions with a constant tension level. Conversely, the high sensibility of fast-twitch units to changes in stimulation frequency enhances their participation in regulation of tension of the muscular contraction.
    Materialart: Digitale Medien
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  • 71
    ISSN: 1432-1106
    Schlagwort(e): Key words Thyroid hormone ; RT-PCR ; p75 receptor ; trkA ; trkB ; trkC ; Septum ; Hippocampus ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Early postnatal application of thyroid hormones to rats results in morphological changes of the septo-hippocampal cholinergic and the hippocampal mossy fiber systems. Modulation in the expression of either neurotrophins and/or their receptors is postulated to be involved in these effects. In a recent study, we showed that, after thyroxine application, the mRNA expression of neurotrophins of the nerve-growth-factor (NGF) family is significantly upregulated both in septum and hippocampus. To test whether the neurotrophin receptors (the low-affinity neurotrophin receptor p75 and the specific high-affinity receptors trkA, trkB, and trkC) were also affected by hormone administration, newborn rats were treated daily with subcutaneous injections of thyroxine until postnatal day 12 (P12) at latest. Control animals received corresponding injections of saline. The pups were sacrificed at defined intervals from P9 to P14. The septal areas and the hippocampi were analyzed using the reverse-transcription polymerase chain reaction (RT-PCR) method for quantification of p75, trkA, trkB, and trkC mRNA levels. Analysis of variance over the total investigation period revealed no significant general increases of the gene expressions of either neurotrophin receptor, neither in the septum nor in the hippocampus, although previous results have shown marked changes in neurotrophin levels. On particular postnatal days, significant upregulation could be observed in hippocampus for trkB and trkC. From these and recent data, we conclude that modulation of neurotrophin expression rather than neurotrophin-receptor expression contributes to the morphological modifications within the hippocampal mossy fiber system and the septo-hippocampal cholinergic system.
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 125 (1999), S. 163-170 
    ISSN: 1432-1106
    Schlagwort(e): Key words Focal cerebral ischemia ; Photothrombosis ; Reperfusion ; Spontaneous recanalization ; Cerebral blood flow ; Edema ; Penumbra ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  In clinical thromboembolic stroke, spontaneous late recanalization is a common feature, but one which has been very sparsely studied experimentally. This study aimed at enabling the study of spontaneous reperfusion and exploring its consequences by modifying a recently developed photothrombotic-stroke model that focuses on the region-at-risk located within an ischemic ring-locus. The exposed crania of male Wistar rats (280–340 g) were subjected to a ring-shaped (5.0 mm outer diameter and 0.35 mm thick) laser-irradiation beam (514.5 nm; 0.89 W/cm2) for 2 min simultaneously with intravenous erythrosin B (17 mg/kg) infusion for 30 s. Transcardial carbon-black perfusion experiments revealed a ring-shaped cortical perfusion deficit at 4 h post-irradiation, which progressively increased at 10, 24, and 48 h, at which time the whole region-at-risk was pale with single distal branches of the middle cerebral artery being extensively narrowed, but not occluded. At 72 h, spontaneous reperfusion was observed in the region-at risk, which was even more pronounced at 7 and 28 days. Cortical cerebral blood flow (cCBF), measured by laser-Doppler flowmetry, was distinctly reduced at 2 min post-irradiation and further decreased slightly during 4 h of recording to ca. 24% of baseline values at the ring locus and 40% in the region-at-risk. In the region-at-risk, cCBF flow values were 23–30% of the baseline at 24–48 h post-irradiation, followed by a relative cCBF increase to 71 and 77% at 72 and 96 h post-irradiation. Brain water content in the ischemic part of the cortex increased steadily from 4 to 48 h post-irradiation; at 72 h, it leveled off and returned to control values at 7 days. In conclusion, by employing a laser beam in the shape of a thin ring, critically sustained cCBF reduction was followed by late, consistent spontaneous reperfusion in the region-at-risk in this novel photochemically induced stroke-in-evolution model.
    Materialart: Digitale Medien
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Surgical and radiologic anatomy 21 (1999), S. 125-131 
    ISSN: 1279-8517
    Schlagwort(e): Wrist joint ; Carpal bones ; Kinematics ; Computed tomography ; Three-dimensional
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A three-dimensional (3D) CT technique was developed to analyze in vivo segmental carpal kinematics. Transverse CT data of the distal forearm, carpals and proximal metacarpals was acquired and 3D reconstructed in various wrist positions. Carpal kinematics were analyzed in two groups of 20 asymptomatic volunteers, one group in neutral position, flexion and extension (45°), and the other group in neutral position, radial (15°) and ulnar deviation (30°). Qualitative analysis included the 3D study of carpal anatomy, and comparison of carpal bone position between the different sets of data obtained. Carpal bone motion was quantified using rigid body and finite helical axis concepts. The results, although agreeing in principle with previous findings, showed important individual variations in carpal bone motion. Clinical applications were conducted in a series of 25 patients with various wrist disorders. There was no significant difference between the injured wrist and the heterolateral, asymptomatic wrist, but there was a significant difference between asymptomatic volunteers and both the injured wrist and heterolateral wrist of patients. In particular, scaphoid motion was altered bilaterally in our patient group, suggesting the existence of anatomic and/or kinematic factors predisposing to certain carpal pathologies. This hypothesis needs to be confirmed and refined.
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 141 (1999), S. 189-196 
    ISSN: 1432-2072
    Schlagwort(e): Key words Acoustic startle response ; Prepulse inhibition ; Sensorimotor gating ; Schizophrenia ; Medial geniculate body ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Prepulse inhibition of acoustic startle is the normal reduction in startle response to an intense auditory stimulus when this stimulus is immediately preceded by a weaker prestimulus. Previous studies have shown that several neuroanatomical structures and pathways in the brain are involved in the modulation of prepulse inhibition. In the present study, the functional importance of the medial geniculate body (MG) in the modulation of prepulse inhibition was investigated. To this end, in vivo brain microdialysis probes were used to infuse drugs locally into the MG of awake, freely moving rats simultaneously with startle response and prepulse inhibition measurements in the same animals. Intrageniculate infusion of the sodium channel blocker, tetrodotoxin, significantly reduced prepulse inhibition without affecting baseline startle amplitude. A similar effect was obtained after intrageniculate infusion of the GABAB receptor agonist, baclofen. In addition, intrageniculate infusion of muscimol, an agonist at the GABAA receptor complex, reduced prepulse inhibition, although this effect was obtained at a higher concentration of the drug compared to that of baclofen. These studies suggest that the MG is involved in the modulation of prepulse inhibition and that auditory signals relayed via the MG may be subjected to inhibitory control at this level, involving GABA neurotransmission.
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  • 75
    ISSN: 1432-2072
    Schlagwort(e): Key words Methamphetamine ; Dopamine ; Serotonin ; Phentermine ; Fenfluramine ; Drug-discrimination ; Self-administration ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  To analyze the involvement of dopamine (DA) and serotonin (5-HT) release in the stimulus properties of methamphetamine, two amphetamine analogs that selectively release either brain DA (phentermine) or 5-HT (fenfluramine) were tested for their ability to substitute for methamphetamine in rats discriminating methamphetamine (1.0 mg/kg) from saline. They were subsequently tested for their ability to alter IV methamphetamine (0.06 mg/kg per injection) self-administration in the same species when given as a pretreatment. The DA releaser phentermine, like methamphetamine itself, decreased methamphetamine self-administration (to 70% of baseline responding), but only at a dose of 3.0 mg/kg that fully generalized to the methamphetamine stimulus in the discrimination study. The 5-HT releaser fenfluramine attenuated methamphetamine self-administration to a much larger extent than phentermine (to 37% of baseline responding) at a dose of 1.8 mg/kg that did not generalize to methamphetamine and did not decrease rate of responding in the discrimination study. Tolerance developed to the inhibitory effect of 1.8 mg/kg fenfluramine on methamphetamine self-administration when it was given repeatedly over four consecutive daily sessions. The fenfluramine-induced decrease in methamphetamine self-administration was also attenuated when it was given together with the small 1.0 mg/kg dose of phentermine. These results suggest that DA release plays a dominant role in the discriminative stimulus effects of methamphetamine. However, stimulation of 5-HT release can strongly modify methamphetamine self-administration.
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  • 76
    ISSN: 1432-2072
    Schlagwort(e): Key words Ethanol ; Self-administration ; Dopamine ; Acetylcholine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In the present study, the reactivity of striatal dopamine and dopamine-sensitive neurons in superfused striatal slices of ethanol-experienced rats was compared to that of ethanol-naive rats, 3 weeks after oral ethanol self-administration. During the acquisition phase (17 days), rats were offered increasing concentrations of ethanol (from 2 to 10%, 24 h per day) on an alternate-day schedule in a free choice with water. Following 2 weeks of unrestricted 10% ethanol consumption, the highest and lowest drinkers (representing about 25% of the upper and lower extremes of the total population) were selected. Preliminary experiments revealed that both groups of rats displayed a profound increase in ethanol consumption and preference 3 weeks after cessation of ethanol self-administration (deprivation effect). This deprivation effect was associated with an increase in electrically evoked release of [3H]dopamine from superfused nucleus accumbens slices, whereas the evoked [3H]dopamine release from caudate putamen slices remained unchanged. In slices of the caudate putamen, but not in nucleus accumbens slices, postsynaptic dopamine D1 receptor-stimulated cyclic AMP production was also enhanced. In addition, prior ethanol consumption enhanced the electrically evoked release of [14C]acetylcholine release in both striatal regions. Interestingly, the magnitude of these long-term neuroadaptations correlated with the amount of daily ethanol consumption, i.e. neuronal hyperresponsiveness in the striatum was more profound in the high than in the low ethanol drinkers. These data show for the first time that unrestricted free-choice ethanol consumption in rats is associated with a long-term increase in dopaminergic and cholinergic neurotransmission in the nucleus accumbens and caudate putamen. These (and other) neuroadaptations may underlie the enhanced motivation to self-administer ethanol and the maintenance of ethanol consumption long after deprivation.
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  • 77
    ISSN: 1432-2072
    Schlagwort(e): Key words NMDA (N-methyl-D-aspartate) ; Schizophrenia ; Prepulse inhibition (PPI) ; Sensory gating ; P50 ; Auditory evoked potentials (AEP) ; Ketamine ; d-Amphetamine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Schizophrenic patients suffer from deficits in information processing. Patients show both a decrease in P50 gating [assessed in the conditioning-testing (C-T) paradigm] and prepulse inhibition (PPI), two paradigms that assess gating. These two paradigms might have a related underlying neural substrate. Gating, as measured in both the C-T paradigm (the gating of a component of the auditory evoked potential (AEP)], and PPI can easily be measured in animals as well as in humans. This offers the opportunity to model these information processing paradigms in animals in order to investigate the effects of neurotransmitter manipulations in the brain. In order to validate the animal model for disturbances in AEP gating, d-amphetamine (0.5 and 1 mg/kg, IP) was administered. Gating of an AEP component was changed due to injection of d-amphetamine (1 mg/kg) in the same way as seen in schizophrenic patients: both the amplitude to the conditioning click and the gating were significantly reduced. Next, the effect of the N-methyl-D-aspartate (NMDA) antagonist ketamine (2.5 and 10 mg/kg, IP) was investigated to assess its effects in the two gating paradigms. It was found that ketamine (10 mg/kg) did not affect gating as measured with components of the AEP. However, ketamine (10 mg/kg) disrupted PPI of the startle response to the extent that prepulse facilitation occurred. Firstly, it is concluded that AEP gating was disrupted by d-amphetamine and not by ketamine. Secondly, PPI and the C-T paradigm reflect distinct inhibitory sensory processes, since both paradigms are differentially influenced by ketamine.
    Materialart: Digitale Medien
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 142 (1999), S. 95-101 
    ISSN: 1432-2072
    Schlagwort(e): Key words Oxytocin ; SSRIs ; Depression ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The nonapeptide oxytocin is released into systemic circulation in situations of psychosocial interaction, and has been shown to be involved in mechanisms of social bonding and social recognition in laboratory studies. In view of disturbances in psychosocial relationships being a triggering factor for depression and anxiety, it is interesting to note that experimental studies have shown oxytocin to possess antidepressant- and anxiolytic-like actions. Thus, in the present study we examined effects of the SSRI citalopram (20 mg/kg IP) on plasma oxytocin, acutely and upon repeated administration, in adult male Sprague-Dawley rats. Plasma oxytocin, and some functionally related peptides (CCK, gastrin, somatostatin and insulin), were measured by standard radioimmunoassay techniques. Acute citalopram administration produced a statistically significant increase in plasma oxytocin and CCK levels. Administration of citalopram for 14 days did not attenuate the oxytocin-releasing effect to a challenge dose of the SSRI zimeldine (20 mg/kg SC), whereas CCK levels were not increased after the subchronic citalopram treatment. Thus, the SSRI citalopram produces increased plasma oxytocin levels acutely, and there appears to be no or little tolerance to this effect upon repeated administration. There were no, or variable, effects on plasma levels of gastrin, somatostatin or insulin. It is suggested that oxytocin release is an important aspect of the pharmacological actions of SSRIs, and this could be an important contributory factor for the clinical profile of this group of antidepressants with particular efficacy in disorders of psychosocial origin.
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  • 79
    ISSN: 1432-2072
    Schlagwort(e): Key words 7-OH-DPAT ; d-Amphetamine ; Dopamine ; Extinction ; Haloperidol ; Progressive-ratio ; Rat ; Self-stimulation ; Ventral tegmental area
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Progressive-ratio (PR) schedules, which have been widely used to study the reinforcing efficacy of various reinforcers (in particular IV psychostimulants), have been very seldom applied to the study of positively reinforcing electrical brain stimulation (EBS). In the present study, rats were required to emit a progressively increasing number of lever-presses (3,4,6,7,9,11,14,16, etc.) for access to successive reinforcers (periods of VTA self-stimulation). Each period of self-stimulation consisted of ten trains of square pulses of EBS; each train was available under a continuous reinforcement schedule. The number of periods of EBS earned during a session was deemed the breaking point (BP). After acquisition and stabilization of self-stimulation, a study was carried out to verify that changes in the strength of the EBS (i.e. changes in the frequency, the intensity or the pulse duration, one parameter at a time) induced changes in the BP. The effects of IP pretreatments with d-amphetamine, the dopamine D3/D2 receptor agonist 7-OH-DPAT and haloperidol were then assessed. Decreases in the strength of EBS decreased the BP. However, increasing the strength above training values resulted in minimal increases in the BP. d-Amphetamine (0.25–1 mg/kg) dose-dependently increased the BP; additionally, when the reinforcer was withheld (i.e. in conditions of extinction, with the stimulator turned off) d-amphetamine was also found to augment the BP. This might indicate that d-amphetamine preferentially potentiated the motivational (non-rewarded presses) aspects of VTA self-stimulation under this type of PR schedule. 7-OH-DPAT had biphasic effects: at low doses (0.01 and 0.03 mg/kg), it tended to decrease the BP while higher doses (1 and 3 mg/kg) robustly increased the BP. Under conditions of extinction, 7-OH-DPAT (1 mg/kg) had a tendency to increase the BP, but this effect was not statistically significant and did not approach the magnitude of effects observed with d-amphetamine. Haloperidol (0.08–0.48 mg/kg IP) dose-dependently reduced the BP, suggestive of a decrease in the reinforcing efficacy of the EBS. These results show that rats can be trained to self-administer EBS of the VTA under a PR schedule of reinforcement and that this behaviour is sensitive to disruption or potentiation of dopaminergic neurotransmission.
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 142 (1999), S. 302-308 
    ISSN: 1432-2072
    Schlagwort(e): Key words Alcohol ; Beer ; Craving ; Rat ; Naloxone ; SR 141716 ; Ritanserin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rats were given two weeks of home cage access to either “near-beer” (a beverage that tastes like beer but contains 〈0.5% ethanol v/v) or near-beer with added ethanol (4.5% v/v), which is simply referred to as “beer”. The two groups of rats (near-beer and beer) were then trained on a “lick-based progressive ratio paradigm” in operant chambers in which an ever increasing number of licks had to be emitted for each successive fixed unit of near-beer or beer delivered. Break points (the ratio at which responding ceased) for near-beer and beer were approximately equal under baseline conditions. Rats were then tested for the effects of the 5HT2A/2C receptor antagonist ritanserin (0.625, 2.5 or 10 mg/kg), the opioid receptor antagonist naloxone (0.625, 2.5 or 10 mg/kg) or the cannabinoid CB1 receptor antagonist SR 141716 (0.3, 1 or 3 mg/kg). All three drugs caused a dose-dependent reduction of break-points and locomotor activity in both the beer and near-beer groups. However, the effects of SR 141716 and naloxone, but not ritanserin, on break-points were significantly more pronounced on rats drinking beer compared to those drinking near-beer. There were no such differential effects of any of the drugs on locomotor activity across the two groups. These results suggest that both SR 141716 and naloxone differentially affect the motivation to consume alcoholic beverages and may thus have potential as drugs for the treatment of alcohol craving.
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  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 142 (1999), S. 327-333 
    ISSN: 1432-2072
    Schlagwort(e): Key words Caffeine ; Nicotine self-administration ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The prevalence of tobacco smoking and coffee drinking place nicotine and caffeine among the most used licit drugs in many societies and their consumption is often characterised by concurrent use. The pharmacological basis for any putative interaction between these drugs remains unclear. Epidemiological reports support anecdotal evidence, which suggests that smokers consume caffeine to enhance the euphoric effects of nicotine. The aim of the present experiment was to examine effects of chronic exposure to caffeine on responding maintained by nicotine. Sprague-Dawley rats consuming caffeine (approximately 150–180 mg/kg per day) in their drinking water for 7 days prior to the beginning and throughout behavioural testing acquired intravenous nicotine self-administration (0.03 mg/kg per infusion) more rapidly than did controls. In a cross-over design, exclusion of caffeine brought levels of nicotine self-administration back to baseline, while adding caffeine to the drinking water of control rats increased responding maintained by nicotine over 90%. These findings strongly suggest that caffeine can potentiate the reinforcing properties of nicotine, thus highlighting the importance of environmental factors in shaping and maintaining tobacco smoking.
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  • 82
    ISSN: 1432-2072
    Schlagwort(e): Key words Continuous cocaine ; Tolerance ; 5-HT3 receptor ; DA release ; Nucleus accumbens ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We have previously reported that continuous cocaine administration functionally down regulates 5-HT3 receptors in the nucleus accumbens. The current experiments evaluated the duration of behavioral tolerance to cocaine and whether the duration of behavioral tolerance and 5-HT3 receptor down-regulation co-varied. Rats were withdrawn from a pretreatment regimen (40 mg/kg/per day cocaine or 0.9% saline for 14 days) for 1, 7 or 14 days. The rats were either sacrificed, and slices from the nucleus accumbens obtained, or were exposed to behavioral rating procedures. The results indicated that continuous cocaine administration significantly attenuated the ability of mCPBG to facilitate K+-stimulated DA release on days 1 and 7, but not day 14, of withdrawal. Furthermore, continuous cocaine administration induced behavioral tolerance to a cocaine challenge on days 1 and 7, but not day 14, of withdrawal. These results suggest that continuous cocaine administration functionally down-regulates 5-HT3 receptors in the nucleus accumbens, and this functional down-regulation co-varies with the behavioral tolerance induced by continuous cocaine administration. Hence, a functional down-regulation of accumbens 5-HT3 receptors may represent a partial mechanism for the tolerance following continuous cocaine administration.
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 142 (1999), S. 369-374 
    ISSN: 1432-2072
    Schlagwort(e): Key words Clozapine ; Withdrawal ; Dependence ; Temperature ; Atypical antipsychotic ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rationale: In schizophrenics, clozapine has been reported to induce various withdrawal signs and rapid onset relapse to psychosis on cessation of chronic treatment. Objective: The study was designed to develop an animal model of one aspect of clozapine tolerance and withdrawal using core body temperature measures. Methods: Two groups of 15 female Wistar rats were treated chronically (b.i.d.) with clozapine at 6 or 12 mg/kg per injection for 21 days prior to cessation of drug treatment, withdrawal being studied over 4 consecutive days. Body temperatures were assessed daily throughout the study. Results: Acutely, clozapine induced dose-related hypothermia, to which complete tolerance developed in both groups, the development of tolerance being more rapid in the group treated with 6 mg/kg per injection of clozapine. During withdrawal only the group treated chronically with 12 mg/kg per injection of clozapine showed rapid onset significant hyperthermia. This dissipated progressively over days, and was completely absent after 4 days of withdrawal. Conclusions: Clozapine induced a clear somatic withdrawal sign after chronic treatment. It is suggested that, in future research in both humans and animals, it is important to attempt to differentiate between clozapine withdrawal and clozapine withdrawal-induced relapse to psychosis. It is also important to characterise the clozapine withdrawal syndrome fully in animals; to establish the neurochemical mechanisms involved in such withdrawal; and to determine which novel antipsychotics are most efficacious in inducing clozapine-like withdrawal effects, in suppressing clozapine withdrawal, and in preventing relapse to psychosis in patients being transferred from clozapine to novel atypical antipsychotic drugs.
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  • 84
    ISSN: 1432-2072
    Schlagwort(e): Key words Ethanol ; Limited access ; Nicotine ; Mecamylamine HCl ; Rat ; Voluntary intake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Observations in humans suggest that the initial use of tobacco occurs in close temporal proximity to experimentation with alcohol. There have been relatively few research reports, however, examining possible interactions between these two agents. The present experiments examined the effect of nicotine exposure on the acquisition of ethanol drinking behavior in a limited access procedure. In experiment 1, rats were presented with 1-h access to ethanol solutions of increasing concentration for a period of 20 days. Subcutaneous injections of nicotine (0.6 or 1.2 mg/kg salt) or vehicle were administered 30 min prior to each ethanol presentation. Experiment 2 used a similar method, but rats were presented with water along with ethanol during the 1-h test session. Mecamylamine, a nicotinic receptor antagonist, was administered 30 min prior to the nicotine treatment. Nicotine was seen to produce a dose-dependent increase in ethanol drinking behavior which commenced at the 5% ethanol concentration and continued at 8% and again at 10%. In the second experiment, mecamylamine was observed to block completely the nicotine-induced increase in ethanol drinking behavior. The findings suggest that exposure to nicotine can facilitate the acquisition of ethanol drinking behavior in naive rats and that this effect is mediated by nicotine’s interaction at the nicotinic-cholinergic receptor.
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  • 85
    ISSN: 1432-2072
    Schlagwort(e): Key words Chlordiazepoxide ; FG 7142 ; Rat ; Diencephalic amnesia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  The intralaminar thalamic nuclei (ILn) have been implicated as a critical site of pathology in amnesia. Lesions of the ILn have been found to produce behavioral effects comparable to benzodiazepine (BDZ) receptor agonists. We compared the effects of chlordiazepoxide (CDP), a BDZ agonist, and FG 7142, a partial inverse agonist at the BDZ receptor, in rats with thalamic lesions and in unlesioned controls. Delayed matching-to sample (DMS) performances were studied during treatment with ascending doses of CDP, counterbalanced trials with 2.5 mg/kg CDP and saline, ascending doses of FG 7142, and (for unlesioned controls only) counterbalanced trials with saline and higher doses of CDP. CDP had effects similar to the ILn lesion, decreasing response speed and percent correct responding in a delay-independent fashion. These effects were additive with the impairments associated with the ILn lesion. The effects of FG 7142 were more complex. At lower doses, it increased response speed without affecting response accuracy. At higher doses, it diminished both the speed and the accuracy of DMS responding. These results support the hypothesis that ILn lesions and BDZ agonists have similar effects on DMS performance. The biphasic effects observed for FG 7142 are consistent with other evidence that low doses of this drug enhance while higher doses impair memory performance. Although DMS accuracy was not improved, the enhancement observed for response speed provides evidence that partial inverse BDZ agonists have potential utility as treatments for cognitive impairments associated with amnesia.
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  • 86
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 143 (1999), S. 54-63 
    ISSN: 1432-2072
    Schlagwort(e): Key words Nicotine ; Midazolam ; Caffeine ; Cocaine ; Amphetamine ; Pentobarbitone ; Ethanol ; Drug discrimination ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rationale: Studies of the discriminative stimulus effects of drug mixtures provide an approach to polydrug abuse and studies on single drugs with multiple effects. Objective: This study was designed to investigate whether the use of the AND-OR procedure increases the specificity of drug mixture discriminations. Methods: Rats were trained to discriminate a mixture of amphetamine (0.4 mg/kg) plus pentobarbitone (10 mg/kg) from saline (AND-discrimination, n = 8) or to discriminate the same mixture from its component drugs alone (AND–OR discrimination, n = 9). The studies used two-lever operant procedures with a tandem variable interval 1-min fixed ratio 10 schedule of food reinforcement. Results: Under AND-discrimination conditions, there was partial generalization to nicotine and midazolam when each drug was administered singly, and there was no generalization to cocaine, caffeine or ethanol. With the AND-OR discrimination, there was no generalization to any of the preceding drugs administered singly. In “single substitution” tests, nicotine or midazolam was co-administered with the training doses of pentobarbitone and amphetamine, respectively; there was full generalization in the AND-discrimination and partial generalization under AND-OR conditions. Cocaine co-administered with pentobarbitone generalized fully under both procedures, but the dose of cocaine needed was much larger in the AND-OR than in the AND-discrimination. In “dual substitution” tests, mixtures of two novel substances were tested. Mixtures of either nicotine plus midazolam or caffeine plus ethanol produced very marked generalization under AND-discrimination conditions, but were without significant effect in the AND-OR procedure. Throughout the studies, in every instance where comparisons were made, generalization was greater or occurred at lower doses under AND- than under the AND-OR discrimination. Conclusions: The study yielded extensive evidence supporting the hypothesis that the AND-OR discrimination procedure increases the specificity of discriminations based on drug mixtures.
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  • 87
    ISSN: 1432-2072
    Schlagwort(e): Key words BC264 ; Cholecystokinin ; CCKB receptor ; Memory ; Ageing ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rationale: The implication of CCKB receptors in cognitive processes is far from fully understood. Objective: The present study investigated the effect of propionyl-BC264, a selective agonist of CCKB receptors, in young and old rats. Methods: Cognitive functions were studied in a two-trial recognition memory task developed in our laboratory. Results: It was shown that propionyl-BC264 enhanced information processing in young as well as in old rats when injected (10 μg/kg; IP) immediately after the acquisition phase and before the retrieval trial but not before the acquisition trial. This cognitive enhancing effect was blocked by prior administration of L 365,260, a selective CCKB receptor antagonist. Conclusions: In view of the fact that BC264 is devoid of anxiogenic effects, it could be of value in the treatment of cognitive impairments associated with both normal and pathological ageing.
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  • 88
    ISSN: 1432-2072
    Schlagwort(e): Key words Antinociception ; Butorphanol ; Relative efficacy ; Opioid ; Rat ; Stimulus intensity ; Tolerance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract   Rationale: A common treatment strategy for the management of severe pain involves the co-administration of multiple opioid analgesics. Due to the increasing popularity of this practice, it is becoming increasingly important to understand the interactions between clinically employed opioids under a wide range of conditions. Objective: The purpose of the present investigation was to examine the effects of opioid combinations following acute and chronic administration of the low-efficacy mu-opioid butorphanol, and to determine if the effects of these combinations are modulated by the intensity of the nociceptive stimulus. Methods: In a warm-water, tail-withdrawal procedure, rats were restrained and the latencies to remove their tails from 50°C (low temperature) and 55°C (high temperature) water were measured following both acute and chronic administration of butorphanol. Opioids possessing both high (etorphine, levorphanol, morphine) and low [dezocine, (–)-pentazocine, nalbuphine] relative efficacy at the mu receptor were examined. Results: Under acute conditions, etorphine, levorphanol, morphine and dezocine increased tail-withdrawal latencies at both low and high temperatures, whereas (–)-pentazocine, nalbuphine and butorphanol increased latencies only at the low temperature. A dose of 30 mg/kg butorphanol increased the effects produced by these opioids at the low temperature, but antagonized the effects of etorphine, levorphanol, morphine and dezocine at the high temperature. During chronic treatment with 30 mg/kg per day butorphanol, tolerance was conferred to the antinociceptive effects of all the opioids examined, with greater degrees of tolerance conferred to those opioids possessing low efficacy at the mu receptor. During butorphanol treatment, etorphine, levorphanol and morphine increased tail-withdrawal latencies at both water temperatures, dezocine increased latencies at only the low temperature, and (–)-pentazocine, nalbuphine and butorphanol failed to increase latencies at either temperature. A dose of 30 mg/kg butorphanol antagonized the antinociceptive effects of etorphine, levorphanol, morphine and dezocine during chronic treatment, and these effects were observed at both water temperatures. Conclusions: These findings indicate that the interactions between butorphanol and other mu opioids vary quantitatively between low and high stimulus intensities, and between acute and chronic conditions. In most instances, however, these interactions can be predicted from the effects of the drugs when administered alone.
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  • 89
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 143 (1999), S. 293-301 
    ISSN: 1432-2072
    Schlagwort(e): Key words Methamphetamine ; Drug discrimination ; Norepinephrine ; Desipramine ; Nisoxetine ; Isoproterenol ; Propranolol ; Methoxamine ; Prazosin ; Clonidine ; Yohimbine ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract   Rationale:Neurochemical and clinical studies indicate involvement of noradrenergic (NE) neurotransmitter system in the actions of methamphetamine. Objective:The present study investigated NE involvement in the discriminative-stimulus effects of methamphetamine. Methods:In Sprague-Dawley rats trained to discriminate 1.0 mg/kg methamphetamine, IP, from saline under a fixed-ratio schedule of food presentation, effects of various NE agonists, antagonists and uptake inhibitors were tested. Results: Desipramine (3.0–18.0 mg/kg) and nisoxetine (5.6–30.0 mg/kg), two selective NE-uptake inhibitors, did not significantly generalize to methamphetamine when administered alone, but 5.6 mg/kg desipramine and 10.0 mg/kg nisoxetine significantly shifted the methamphetamine dose-response curve to the left. The beta NE agonist, isoproterenol (0.56–3.0 mg/kg), and antagonist, propranolol (1.0–18.0 mg/kg), neither generalized to methamphetamine when given alone nor altered the discriminative-stimulus effects of methamphetamine when administered in combination. The alpha-1 NE agonist methoxamine (1.0–5.6 mg/kg) failed to generalize to the methamphetamine training stimulus. When given in combination with methamphetamine, the alpha-1 NE antagonist, prazosin (1.0 mg/kg), shifted the methamphetamine dose-response curve somewhat to the right and partially blocked the discriminative-stimulus effects of the 1.0 mg/kg training dose of methamphetamine, but these changes were not significant or dose-related, with further increases in prazosin dose (1.8–10.0 mg/kg) either producing similar or smaller changes. The alpha-2 NE agonist, clonidine, partially generalized to methamphetamine at doses of 0.1–0.18 mg/kg and increased drug-appropriate responding at lower doses of methamphetamine, but it partially blocked the discriminative-stimulus effects of higher 0.56–1.0 mg/kg doses of methamphetamine over the same dose range. The alpha-2 NE antagonist, yohimbine, also partially generalized to methamphetamine and blocked the discriminative-stimulus effects of the 1.0 mg/kg training dose of methamphetamine at doses of 5.6–10.0 mg/kg. A lower 3.0 mg/kg dose of yohimbine increased methamphetamine-appropriate responding when given together with low 0.1–0.3 mg/kg doses of methamphetamine. Conclusions:The present data suggest that the NE system plays a modulatory role in the discriminative-stimulus effects of methamphetamine. These effects appear to be mediated through NE uptake sites and alpha-2 receptors, with limited involvement of alpha-1 receptors and beta receptors.
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  • 90
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 143 (1999), S. 315-317 
    ISSN: 1432-2072
    Schlagwort(e): Key words SR141716 ; Hyperphagia ; Rat ; Pre-feed ; Eating ; Appetite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract   Rationale: Central cannabinoid systems have been implicated in appetite regulation by the respective hyperphagic actions of exogenous cannabinoids, such as Δ9-THC, and hypophagic effects of selective cannabinoid receptor antagonists. Objective: This study examined whether an endogenous cannabinoid, anandamide, could induce overeating, via a specific action at central (CB1) cannabinoid receptors. Methods: Pre-satiated male rats (n=18), received subcutaneous injections of anandamide (0.5, 1.0, 5.0, 10.0 mg/kg) before 3-h, nocturnal food intake tests. In a second series of intake tests (n=8), anandamide injection (1.0 mg/kg) was preceded by injection of the specific CB1 receptor antagonist, SR141716 (0.1, 0.5, 1.0 mg/kg SC). Results: All doses of anandamide induced significant overeating, with 1.0 mg/kg being most potent. Additionally, hyperphagia induced by 1.0 mg/kg anandamide was dose-dependently attenuated by SR141716 pretreatment. Conclusion: This first demonstration of anandamide-induced, CB1-mediated, overeating provides important evidence for the involvement of a central cannabinoid system in the normal control of eating.
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  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 143 (1999), S. 318-321 
    ISSN: 1432-2072
    Schlagwort(e): Key words Nicotine ; Cotinine ; Self-administration ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract   Rationale: The route of nicotine administration between animal models and humans is very different and further investigation by determining levels of nicotine entering into the circulatory system is warranted. Objective: The present study addresses the validity of the rat self-administration procedure by comparing plasma levels of nicotine in the rat with levels reported in smokers following cigarette consumption. Methods: Plasma levels of nicotine and its metabolite cotinine were measured in 17 rats following intravenous self-administration of a range of nicotine doses (0.015, 0.03 and 0.06 mg/kg per infusion). Results: The two larger unit doses supported reliable self-administration behaviour with no overall difference in the patterns of nicotine intake. However, the total nicotine intake over the 2-h session was related to unit dose and this correlated highly with nicotine and cotinine levels measured in blood collected from the tail vein. On average, cotinine levels (50–200 ng/ml) were approximately 2-fold higher than nicotine levels (40–120 ng/ml) in plasma. Following an extinction test for one session in which saline was substituted for nicotine, no change in behaviour was observed in the two groups, while plasma levels of nicotine and cotinine dropped to nominal levels. Conclusions: The concentrations of nicotine attained following nicotine self-administration appear to be similar to levels reported in smokers after cigarette consumption, providing further validation of this procedure as an animal model of nicotine dependence.
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  • 92
    ISSN: 1432-2072
    Schlagwort(e): Key words MDMA (3 ; 4-methylenedioxymethamphetamine) ; Serotonin ; Psychopathology ; Human ; Rat ; Prepulse inhibition ; Habituation ; Schizophrenia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rationale: Prepulse inhibition of acoustic startle refers to the reduction in the startle response when the startling stimulus is preceded by a weak prepulse stimulus. This phenomenon provides an operational measure of sensorimotor gating that has been found to be reduced in patients with schizophrenia and rats treated with serotonin agonists or serotonin releasers. Objective: In this study, we compared the effects of a serotonin releaser, MDMA, on prepulse inhibition in laboratory rats and healthy human volunteers. In particular, we investigated whether MDMA disrupts PPI in humans as observed in animal studies. Methods: Rats were tested after placebo and MDMA in a counterbalanced order at an interval of 1 week, with separate groups of rats being used for each dose of MDMA (1.7, 5.4 and 17.0 mg/kg). On each test day, rats were first tested after no injections and retested 2 h later, 10 min after a subcutaneous injection of placebo or MDMA. For the human study, a placebo-controlled within-subject design and double-blind procedures were used. Subjects were examined twice at a 2 to 4 week interval after either placebo or drug administration (order being counterbalanced). On each test day, subjects underwent baseline testing including psychological and PPI measures. Ninety minutes later, subjects received placebo or MDMA (1.7 mg/kg PO) and were retested after 75 min during the peak of behavioral effects of MDMA. Results: As expected, MDMA decreased prepulse inhibition in a dose-related fashion in rats. In contrast, a typical recreational dose of MDMA (1.7 mg/kg, orally) increased prepulse inhibition in subjects experiencing robust psychological effects. Conclusions: This surprising disparity between the effects of the drug in rats and humans may reflect a species-specific difference in the mechanism of action of MDMA or in the behavioral expression of a similar pharmacological effect, or both.
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  • 93
    ISSN: 1432-2072
    Schlagwort(e): Key words Amphetamine ; Fluoxetine ; Intracranial self-stimulation thresholds ; Withdrawal ; Depression ; Selective serotonin reuptake inhibitors ; Psychostimulant ; Reward ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Rationale: Withdrawal from chronic amphetamine administration is characterized by deficits in reward that resemble some symptoms of depression. Nevertheless, the effects of long-term administration and withdrawal from other drugs, such as fluoxetine, that have the potential to elevate mood in depressed individuals have not been characterized. Objectives: The purpose of this study was to characterize the effects of withdrawal from chronic amphetamine or fluoxetine administration on central reward function. Furthermore, the effects of acute or chronic pretreatment with fluoxetine on responsiveness to an acute amphetamine challenge were examined to identify potential interactions between the two drugs. Methods: A rate-independent discrete-trial threshold procedure was used to characterize self-stimulation behavior in rats prepared with bipolar electrodes in the medial forebrain bundle. Results: Elevations in intracranial self-stimulation (ICSS) thresholds, reflecting a decrease in the reward value of the stimulation, were associated with withdrawal from various chronic amphetamine treatment regimens (1–5 mg/kg, three injections per day for 1, 2, 4 or 6 days). The magnitude and duration of threshold elevations were proportional to the duration and dose of amphetamine treatment prior to withdrawal. In contrast, no alterations in ICSS thresholds were associated with withdrawal from chronic fluoxetine treatment (5 mg/kg/day for 15 days). While neither acute nor chronic administration of fluoxetine alone altered ICSS thresholds, chronic pretreatment with fluoxetine blocked the threshold-lowering effect of acute amphetamine administration (4 mg/kg), but acute pretreatment did not. Amphetamine-induced decreases in response latency, a measure of motor performance, were not affected by either chronic or acute fluoxetine pretreatment. Conclusions: The results of these experiments suggest that chronic fluoxetine treatment may induce adaptive changes in serotonergic transmission that, in themselves, do not alter the function of central reward processes, but may alter the ability of amphetamine to potentiate ICSS reward. In addition, the lack of change in ICSS thresholds during withdrawal from the chronic fluoxetine treatment regimen used suggests that withdrawal from all mood-altering drugs may not necessarily produce changes in central reward functions.
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 147 (1999), S. 250-256 
    ISSN: 1432-2072
    Schlagwort(e): Key words Locomotion ; Activity ; Dose-response ; Time-course ; Anticholinergic drug ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Rationale: In order to facilitate direct comparisons of anticholinergic drug effects on activity, nine drugs were tested in one laboratory using a standardized procedure. Objective: The present study compared the effects of aprophen hydrochloride, atropine sulfate, azaprophen hydrochloride, benactyzine hydrochloride, biperiden hydrochloride, diazepam, procyclidine hydrochloride, scopolamine hydrobromide, and trihexyphenidyl hydrochloride on activity levels in rats. Methods: Both fine motor activity (reflecting smaller movements) and ambulatory activity (reflecting larger movements) were recorded for 23 h following drug administration in food-restricted rats. All drugs were administered during the light period of the photocycle. Results: Atropine, azaprophen, biperiden, scopolamine, and trihexyphenidyl increased both ambulations and fine motor activity significantly during the first hour post-injection, but the increased activity levels returned to vehicle control levels within 2–6 h post-injection. Benactyzine and procyclidine only increased fine motor activity significantly above vehicle control levels and activity levels returned to vehicle control levels within 2–3 h. Finally, aprophen and diazepam generally did not increase measures of activity significantly above vehicle controls at the dose ranges examined. Conclusions: Based on potencies relative to scopolamine, the potency of the drugs could be ranked as follows: scopolamine 〉 trihexyphenidyl 〉 biperiden 〉 azaprophen 〉 procyclidine 〉 benactyzine 〉 atropine 〉 aprophen. The comparison of drug effects on activity may be useful in selecting anticholinergic drug therapies with a minimal range of side effects. In addition, these data may reduce the number of anticholinergic drugs that need to be tested in comparison studies involving more complex behavioral tests.
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  • 95
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 144 (1999), S. 239-247 
    ISSN: 1432-2072
    Schlagwort(e): Key words Dezocine ; Morphine ; 7-OH-DPAT ; Quinpirole ; SKF38393 ; SCH23390 ; Rat ; Warm-water tail-withdrawal ; Antinociception
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Rationale: The purpose of the present investigation was to evaluate the effects of the D3 agonist (±)-7-hydroxy-dipropylaminotetralin (7-OH-DPAT), various dopamine (DA) agonists and DA antagonists on the antinociceptive effects of μ opioids. Methods: Antinociception was assessed using a warm-water tail-withdrawal procedure in rats. Results: The μ opioids morphine (0.3–10 mg/kg) and dezocine (0.03–3.0 mg/kg) produced dose-dependent increases in antinociception with maximal effects obtained at the higher doses tested. Pretreatment with the putative D3 agonist 7-OH-DPAT (1.0–10 mg/kg) produced a dose-dependent attenuation of the antinociceptive effects of morphine and dezocine. At the highest dose of 7-OH-DPAT tested, the morphine dose-effect curve was shifted rightward by approximately 1.5 log units and the dezocine curve by greater than 2.3 log units. The (+)-isomer of 7-OH-DPAT (1.0 and 3.0 mg/kg) also shifted the morphine dose-effect curve to the right in a dose-dependent manner. The DA D3/D2 agonist (−)-quinpirole (0.1–10 mg/kg) attenuated the effects of morphine, but these effects were small in magnitude, not dose-dependent and observed only under a limited set of conditions. The DA D2/D3 antagonist spiperone failed to alter the morphine dose-effect curve, but reversed the effects of 7-OH-DPAT on morphine antinociception. Pretreatment with the DA D1 agonist (±)-SKF38393 (1.0 and 10 mg/kg) and the D1 antagonist (+)-SCH23390 (0.1 and 1.0 mg/kg) failed to alter the morphine dose-effect curve. Conclusion: The finding that 7-OH-DPAT markedly attenuated the effects of morphine and that these effects were reversed with spiperone suggests that activity at the D3, and possibly the D2, receptor can modulate μ agonist-induced antinociception.
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  • 96
    ISSN: 1432-2072
    Schlagwort(e): Key words Hippocampus ; Lesion ; Glutamate receptor and release ; Dopamine receptor ; Locomotor activity ; Schizophrenia ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In 6-week and 8-week-old rats (pre- and postpubertally) with neonatal excitotoxic lesions of the ventral hippocampus with ibotenic acid (IBO), we have studied apomorphine-induced motor activity and glutamate and dopamine D1 and D2 binding sites in the hippocampus, striatum, nc. accumbens and frontal cortex as well as K+-stimulated (3H)-D-aspartate release from hippocampal and frontal cortical slices. Specific glutamate binding was enhanced in the frontal cortex of 8-week-old IBO-treated animals, whereas that in other brain regions remained unchanged. Both D1 and D2 binding sites were downregulated in the striatum without changes in other brain structures. In 6-week-old rats, neither the glutamate nor the dopamine binding sites were altered. The amino acid release from hippocampal and frontal cortical slices of adult IBO treated rats was significantly decreased in comparison to controls, whereas in 6-week-old rats, no significant alterations were detectable. The additionally monitored motor activity was enhanced only in adult IBO-lesioned rats after apomorphine pretreatment. The present data are in agreement with the hypothesis of hyperactive dopamine and hypoactive glutamate systems in schizophrenia and are discussed in the light of schizophrenia-like behavioral changes in rats after postnatal hippocampal IBO lesion.
    Materialart: Digitale Medien
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 145 (1999), S. 153-161 
    ISSN: 1432-2072
    Schlagwort(e): Key words Cocaethylene ; Cocaine ; Alcohol ; Interaction ; Schedule-controlled responding ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Rationale: Cocaethylene is a unique metabolite of cocaine, produced only in the presence of alcohol. This metabolite is pharmacologically, physiologically and behaviorally active. Further, it has been reported to interact pharmacokinetically with both cocaine and alcohol, an interaction that may mediate, in part, the interaction of cocaine and alcohol. Although cocaethylene has been shown to interact with both cocaine and alcohol, behavioral assessments of these interactions are limited. Objectives: To examine directly the behavioral interactions between cocaethylene and cocaine and between cocaethylene and alcohol, the present study assessed the effects produced by these combinations on schedule-controlled responding. Methods: Rats were first administered cumulative doses of cocaethylene, cocaine and alcohol to assess their effects alone on responding. Following this, doses of cocaethylene were combined with cumulative doses of cocaine or alcohol. Additionally, doses of cocaine or alcohol were given in combination with cumulative doses of cocaethylene. Results: When administered alone, cocaethylene, cocaine and alcohol produced dose-related decreases in responding. Further, cocaethylene shifted the dose–response functions for both cocaine and alcohol to the left and down, while cocaine and alcohol shifted the dose–response function for cocaethylene to the left and down. An isobolographic analysis revealed that these interactions were additive in nature. Conclusions: The present study suggests behavioral interactions between cocaethylene and cocaine and between cocaethylene and alcohol. The contribution of cocaethylene to the enhanced effects produced by the co-administration of cocaine and alcohol was discussed.
    Materialart: Digitale Medien
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  • 98
    ISSN: 1432-2072
    Schlagwort(e): Key words Ibogaine ; Cocaine ; Dose-response ; Locomotor activity ; Sensitization ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Rationale: Results of single-dose studies suggest that the effects of pretreatment with the putative anti-addictive compound, ibogaine, on drug-induced locomotor behavior depends on the previous drug history of the animal. Objectives: To compare the effects of ibogaine pretreatment on the dose-locomotor response function for cocaine in rats treated chronically with either saline or cocaine. Methods: Rats were chronically treated with either cocaine (15 mg/kg, IP, once daily for 5 days, followed by 2 week withdrawal) or saline. Ibogaine (40 mg/kg, IP) or vehicle was administered and 19 h later, a cocaine dose-locomotor response test was conducted (0, 5, 10, 20 and 40 mg/kg, IP). Results: Chronic cocaine administration augmented the locomotor response to cocaine in chronic cocaine-treated rats, compared to acutely treated controls. Ibogaine pretreatment enhanced the locomotor effects of cocaine in both chronic and acute cocaine groups. Furthermore, due to the shape of the dose-response curve, in chronic cocaine but not in acute cocaine rats, ibogaine pretreatment enhanced the locomotor response to 5 and 10 mg/kg cocaine while decreasing the locomotor response to 40 mg/kg cocaine. Conclusions: These data demonstrate definitively that ibogaine can enhance sensitivity to the locomotor stimulant effects of cocaine, an effect which depends, in part, on the previous cocaine history of the animal.
    Materialart: Digitale Medien
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  • 99
    ISSN: 1432-2072
    Schlagwort(e): Key words Nicotine ; Nornicotine ; Behavioral sensitization ; Locomotor activity ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Rationale: Nicotine, a tobacco alkaloid, is known to be important in the acquisition and maintenance of tobacco smoking. Nornicotine, an active nicotine metabolite, stimulates nicotinic receptors and may produce psychomotor effects similar to nicotine. Objective: The present study determined the effects of acute and repeated administration of nornicotine on locomotor activity and compared its effects with those of nicotine. Methods: R(+)-Nornicotine (0.3–10 mg/kg), S(–)-nornicotine (0.3–10 mg/kg), S(–)-nicotine (0.1–1 mg/kg) or saline was administered s.c. to rats acutely or repeatedly (eight injections at 48-h intervals). Activity was recorded for 50 min immediately after each injection. Results: S(–)-Nicotine produced transient hypoactivity, followed by dose-related hyperactivity. Repeated S(–)-nicotine administration resulted in tolerance to the hypoactivity and sensitization to the hyperactivity. Subsequent testing following a saline injection revealed evidence of conditioned hyperactivity. Acute administration of 0.3 mg/kg or 1 mg/kg R(+)- or S(–)-nornicotine produced no effect. Transient hypoactivity was observed at 3 mg/kg and 10 mg/kg R(+)-nornicotine and at 10 mg/kg S(–)-nornicotine. However, rebound hyperactivity was not observed following acute administration of either nornicotine enantiomer, suggesting that nornicotine-induced psychomotor effects differ qualitatively from those of S(–)-nicotine. Repeated R(+)-nornicotine resulted in tolerance to the transient hypoactivity, however hyperactivity was not observed. Repeated S(–)-nornicotine resulted in tolerance to the hypoactivity and the appearance of hyperactivity. Repeated administration of either nornicotine enantiomer resulted in a dose-dependent alteration in response to a 1 mg/kg S(–)-nicotine challenge, suggesting some commonalities in the mechanism of action. Conclusion: Nornicotine likely contributes to the neuropharmacological effects of nicotine and tobacco use.
    Materialart: Digitale Medien
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Psychopharmacology 146 (1999), S. 19-23 
    ISSN: 1432-2072
    Schlagwort(e): Key words Serotonin ; Sensitization ; Rat ; Dopamine opiate ; Movement disorder
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract   Rationale: Repeated high doses of morphine in the rat cause stereotypic gnawing behavior that can be re-expressed by a low dose of morphine weeks and even months after the initial treatment. The determination of the role of serotonin in this sensitized morphine-induced behavior has both empirical and theoretical relevance. Objectives: To determine whether the serotonin-reuptake blocker fluoxetine will block the development and/or the expression of this opiate-induced stereotypy. Methods: Rats were given four 10-mg/kg injections of morphine alone or with 5.0 mg/kg fluoxetine over a 36-h period. At weekly intervals for 6 weeks after the last of the sensitizing morphine doses, all rats were challenged with 4.0 mg/kg morphine. At week 2 and week 4, however, the morphine was co-administered with fluoxetine. Results: Fluoxetine completely blocked the expression of the morphine-induced stereotypy; however, when the morphine/fluoxetine-treated rats were challenged with morphine alone, they expressed similar degrees of stereotypy as the rats that initially only received morphine. Conclusions: The results indicate that increasing synaptic serotonin will block the expression but not the development of sensitization to the oral stereotypic effects of repeated high doses of morphine. Also, despite the complete blocking of the morphine effect by fluoxetine during the sensitization phase, the presence of significant biting by these rats during the challenge with morphine alone argues that conditioning factors are not a necessary component for the morphine sensitization to develop.
    Materialart: Digitale Medien
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