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  • 1995-1999  (946)
  • 1999  (946)
  • General Chemistry  (750)
  • Human  (119)
  • CT  (77)
  • Atomic, Molecular and Optical Physics
  • Inorganic Chemistry
  • Nuclear reactions
Material
Years
  • 1995-1999  (946)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Surgical and radiologic anatomy 21 (1999), S. 139-141 
    ISSN: 1279-8517
    Keywords: Anatomy ; Human ; Cross-section ; Computer-assisted instruction ; Education ; Medical
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The NPAC visible human viewer (NPAC VHV), graphical interface written in JAVA, freely accessible by the Web, allows the display of anatomic cross-sections of the Visible Human Project developed by the National Library of Medicine. In April 1997, the Medical Media Library of Lyons undertook the construction of a French-language mirror site of the NPAC VHV. The aim of this work is to evaluate first year utilisation of this site. From May 1st, 1997 to April 30th, 1998, the mirror site was consulted 34,752 times. In 45.14% of cases, the request came from France, in 4.42% of cases from Belgium, in 3.98% from Canada and in 2.12% from Switzerland. Other connections came either from a country responsible for fewer than 1% of connections or from unidentified computers. Data analysis showed a peak of connections between 15:00 and 17:00, and an increased number of connections from September to March 1998. The NPAC VHV is housed in 5 sites in the world. It is a software very simple to use. As the figures have no legends, it is more appropriate for group teaching than for self-teaching.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1279-8517
    Keywords: Liver ; CT ; Neoplasms ; Arteries, therapeutic blockade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The goals of this study were to delineate the boundary between the right and left hepatic artery territories by computed tomography (CT), to compare this boundary with the middle scissura of Couinaud’s segmental anatomy, and to discuss the clinical implications of these findings. The 18 patients who underwent transcatheter oily chemoembolization (TOCE) of liver tumors via the right or left hepatic artery, were examined with an immediate postembolization CT scan. We measured the orientation of the watershed line between the right and left hepatic artery territories and the orientation of the middle scissura on other available sectional imaging modalities, and then compared the middle scissura with the arterial watershed line. A part of segment IV was fed by the right hepatic artery in two of 18 (11.1%) patients. Moreover, one of 4 segment IV lesions was embolized via right hepatic artery infusion. Thus, in 11.1% of cases there was no coincidence between the arterial watershed line and the middle scissura. Some segment IV lesions may be fed and therefore embolized only via right hepatic artery infusion in TOCE for liver tumor.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1438-1435
    Keywords: Key words Hepatic lymphedema ; CT ; Hemopericardium ; CT ; Aneurysm ; rupture ; Aorta ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: To correlate computed tomography (CT) findings with clinical-pathologic results and discuss the possible significance of periportal hypodensity in patients with clinical cardiac tamponade secondary to acute proximal thoracic aortic dissection, aneurysm, or heart rupture. Materials and methods: In a retrospective review of thoracoabdominal CT scans and records of 17 consecutive patients with hemopericardium, 10 patients with clinical signs of cardiac tamponade associated with hypodensity around the portal vein were selected; at surgery or autopsy all 10 patients had a thoracic aortic aneurysm, dissecting aneurysm, and heart rupture. The ratio of transverse inferior vena cava diameter to the diameter of the aorta at the level of the right adrenal gland was determined. Results: Abdominal CT scans showed focal (n = 1) or diffuse (n = 9) areas of hypodensity around the portal vein associated with pericaval hypodensity in four cases. Other abdominal abnormalities included persistent enhancement of renal parenchyma (n = 5), and gallbladder wall edema (n = 2); in nine cases the inferior vena cava diameter was significantly increased compared with that of patients with normal findings on CT scans (P 〈 0.01). Pathologic correlation, available in nine cases by autopsy, showed evidence of periportal lymphatic vessel dilatation and lymphedema. Conclusions: Periportal hypodensity on CT scans corresponds to the histopathologic picture of dilated lymphatic vessels or hepatic lymphedema; a diagnosis of hepatic lymphedema may be considered on the basis of CT scans in patients with pericardial effusion.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Emergency radiology 6 (1999), S. 113-120 
    ISSN: 1438-1435
    Keywords: Key words Computed tomography (CT) ; helical ; Pancreatitis ; Pancreas ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acute pancreatitis represents one of the more commonly encountered etiologies of acute abdominal pain. Many complications can present emergently, including pancreatic abscess, necrosis, and hemorrhage. The purpose of this pictorial essay is to educate the reader about the spectrum of CT findings in patients with complications from pancreatitis. Emphasis is placed on evaluation with helical CT, stressing optimal technique and the imaging parameters essential for accurate diagnosis.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Emergency radiology 6 (1999), S. 204-209 
    ISSN: 1438-1435
    Keywords: Key words Neoplasms ; Hemorrhage ; Perforation ; CT ; Abdomen ; Pelvis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rupture of tumors is usually a critical and life-threatening condition. We demonstrate a wide variety of ruptured tumors with their imaging characteristics including gastric lymphoma, gastric leiomyosarcoma, leiomyosarcoma of the ileum, hepatocellular carcinoma, pancreatic pseudocyst, renal angiomyolipoma, renal cell carcinoma, ovarian endometrial cyst, ovarian corpus luteum cyst, and ovarian teratoma. Their imaging features are illustrated with an emphasis on clues to an accurate diagnosis.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Emergency radiology 6 (1999), S. 232-243 
    ISSN: 1438-1435
    Keywords: Key words Abdomen ; CT ; Abdomen ; acute conditions ; Retroperitoneal space ; CT ; Retroperitoneal space ; injuries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The retroperitoneum is a common location for injury following blunt or penetrating trauma. Additionally, there are a wide variety of nontraumatic emergencies that involve the retroperitoneum. Patients with these entities may present with symptoms ranging from acute abdominal or back pain to hypotension and/or fever. Computed tomography (CT) is the imaging modality of choice to evaluate acute processes of the retroperitoneum, as sonography has been historically less sensitive than CT. Knowledge of the compartments of the retroperitoneal space as well as the fascial planes is crucial to diagnose and understand the pathway of spread of pathology in this region. In this pictorial essay the spectrum of both traumatic and nontraumatic retroperitoneal emergencies will be demonstrated, as well as their effect on the different compartments of the retroperitoneum.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1438-1435
    Keywords: Key words Pericardium ; Rupture ; Heart luxation ; Chest X-ray ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This report describes a patient who presented to our hospital in stable condition without signs of circulatory or respiratory failure following previous surgery for blunt abdominal trauma. The diagnosis of rupture of the pericardium with luxation of the heart was suggested on chest X-ray and CT. Left anterior thoracotomy revealed a 6-cm longitudinal left pericardial tear with herniation of the heart into the mediastinum.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1437-1596
    Keywords: Key words Poisoning ; Benfuracarb ; Carbofuran ; Human ; Blood ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Notes: Abstract We describe here three cases involving acute fatalities due to benfuracarb ingestion and the forensic toxicological implications. Benfuracarb, a carbamate insecticide and its main metabolite carbofuran, were detected using thin layer chromatography (TLC) and gas chromatography/mass spectrophotometry (GC/MS) after extraction with ethyl acetate and then quantified using gas chromatography (GC) equipped with NPD. The blood levels of benfuracarb and carbofuran were in the range of 0.30∼2.32 μg/ml and 1.45∼1.47 μg/ml, respectively. Benfuracarb was not detected in urine, but carbofuran was detected in the range of 0.53∼2.66 μg/ml.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 125 (1999), S. 389-396 
    ISSN: 1432-1106
    Keywords: Key words Neck muscles ; Vibration ; Proprioception ; Sound localization ; Space perception ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effect of transcutaneous vibration of the posterior neck muscles on the lateralization of dichotic sound was investigated in human subjects. Two-alternative forced-choice (left/right) judgements were made on acoustic stimuli presented with different interaural level differences via headphones during neck-muscle vibration. A shift of the subjective auditory median plane toward the side contralateral of vibration was found, indicating that the sound was perceived as shifted toward the side of vibration. The mean magnitude of the vibration-induced intracranial shift was 1.5 dB. The results demonstrate a neck-proprioceptive influence on sound lateralization and suggest that this proprioceptive input is used for a central-nervous transformation of auditory spatial coordinates onto a body-centered frame of reference.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 125 (1999), S. 435-439 
    ISSN: 1432-1106
    Keywords: Key words Transcranial magnetic stimulation ; Plasticity ; Synchronization ; Motor system ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We used focal transcranial magnetic stimulation to examine the effects of 120 synchronized thumb and foot movements on the motor output map of the right abductor pollicis brevis muscle (APB) (experiment 1). To evaluate the performance, the latencies between the onset of the electromyographic activity (EMG) of the two muscles were measured. As control, 120 asynchronous thumb and foot movements were performed (experiment 2). Exclusively in experiment 1, the center of gravity (CoG) of the output map moved medially in the direction of the foot representation area (mean 7 mm, P〈0.05) and returned into its original location within 1 h. In experiment 2, the CoG remained unchanged (mean displacement, 0.68 mm into a lateral direction; not significant). The effect in experiment 1 was independent of an improvement in performance. We conclude that a short-lasting training of synchronous movements induces modulations of motor output maps which probably occur due to interactions between hand and foot representation areas in the motor cortex.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 185 (1999), S. 297-304 
    ISSN: 1432-1351
    Keywords: Key words Odor coding ; Learning ; Enhanced sensitivity ; Rabbit ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The olfactory system is faced with a particular problem – the high dimensionality and inherent unpredictability of the chemical world. Most natural odorants encountered in everyday life are complex mixtures of many different volatiles. This means that from the outset the olfactory system has to contend with a great and often unpredictable diversity of molecules, making it difficult for stable primary features of the chemical world to be mapped onto the sensory surface. One solution to such unpredictability is provided by learning. Learning confers flexibility, enabling individuals of a given species to acquire and make use of the most appropriate information in a particular environment. Two examples of this are presented: learning of maternal odors in neonatal rabbits, including evidence that the sensory surface itself may be influenced by environmental conditions so as to enhance sensitivity to molecules of particular ecological relevance, and cross-cultural human studies suggesting that experience with everyday odors influences not only the way these are evaluated, but also their perceived intensity. It is concluded that an adequate understanding of odor coding and olfactory function will not be possible without taking such experience-dependent factors into account.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 28 (1999), S. 33-40 
    ISSN: 1432-2161
    Keywords: Key words Osteoblastoma ; Spine ; Radiography ; CT ; MRI ; Pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objectives. To illustrate the CT and MRI features of spinal osteoblastomas and correlate the imaging with histological findings. Design. In a retrospective review the CT and MRI features of spinal osteoblastomas with respect to mineralisation, signal intensity (SI), adjacent reactive changes, enhancement following gadolinium-DTPA (5 cases) and adjacent soft tissue masses were compared and correlated with the histological findings including the degree of osteoid formation and matrix mineralisation, vascularity and surrounding reactive changes in bone and soft tissue. Patients. Eleven patients (7 males and 4 females; age range 8–43 years, mean age 19.5 years) with 12 osteoblastomas (1 patient suffered a recurrence) were studied. Results. All lesions showed classical features on CT with varying degrees of matrix mineralisation, whereas MRI identified mineralisation in only eight of 12 cases. MRI showed low signal intensity of the lesion on both T1- and T2-weighted sequences in several cases in the absence of heavy mineralisation. In these cases, histological examination revealed diffuse osteoid production by the tumour. All patients given gadolinium showed enhancement within the tumour on MRI. Reactive bone marrow changes were identified on MRI in 10 cases, and in five of these the changes were at multiple levels. An adjacent soft tissue mass was demonstrated in five cases, but extraosseous tumour was present histologically in only two of these. Conclusions. The MRI appearances of spinal osteoblastomas are varied and show no characteristic features. MRI may also overestimate the extent of the lesion due to extensive reactive changes and adjacent soft tissue masses. CT should continue to be the investigation of choice for the characterisation and local staging of suspected spinal osteoblastomas.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 28 (1999), S. 49-51 
    ISSN: 1432-2161
    Keywords: Key words Cryptococcoma ; sacrum ; Cryptococcoma ; immunocompromised ; MRI ; sacrum ; CT ; sacrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Cryptococcoma of the sacrum was the initial presentation of systemic cryptococcosis in a patient on chronic steroid therapy for autoimmune hepatitis. The bone lesion was the only overt manifestation of systemic cryptococcal disease, which preceded other clinical manifestations and led to the subsequent diagnosis of systemic infection.
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  • 14
    ISSN: 1432-2161
    Keywords: Key words Osteosarcoma ; conventional ; Metastasis ; Soft tissues ; Retroperitoneum ; CT ; X-ray
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Osteosarcoma (osteogenic sarcoma) metastasizes primarily to the lung. With the introduction of neoadjuvant chemotherapy as part of the treatment, the overall and disease-free survival rates have dramatically improved. In this case report, a young man with multiple soft tissue and bone metastases, including a rare large bone-forming retroperitoneal metastasis, is described. Despite the extensive extrapulmonary metastases, the patient did not develop pulmonary metastases in the 4 years following initial presentation of the primary tumour.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 28 (1999), S. 717-722 
    ISSN: 1432-2161
    Keywords: Key words Sarcoid ; vertebrae ; Sarcoid ; rib ; Sarcoid ; calvarium ; Osteolytic ; CT ; MRI ; Surgical fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Skeletal sarcoidosis is rare. This report describes a 31-year-old African American man who presented with a destructive osteolytic lesion of C2 and another lesion in a rib. The lesion at C2 was treated with corpectomy and bone graft. Four months later the lesion recurred and a new lesion was discovered in the cervical vertebral column. The patient declined surgery for instability for another 3 months, choosing to remain in a halo. Seven months following the initial operation, a technetium bone scan showed spread of the disease to the calvarium and thoracic and lumbar vertebrae. The patient had no symptoms referable to these sites. The patient agreed to have his neck fused at this point. For the next 10 months, the patient was on steroids and a further new lesion appeared at L5 without localizing signs or symptoms. The patient declined further evaluation over the next 12 months and is now considered lost to follow-up.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1432-2161
    Keywords: Key words Stress fractures ; CT ; MR imaging ; Radionuclide study ; Femur ; stress fractures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We present five cases of a distinctive type of longitudinal stress fracture of the upper femoral shaft in which the fracture line is parallel to the outer surface of the bone, in contrast to the perpendicular orientation to the cortical surface in previously reported cases of diaphyseal stress fractures. In two cases the fracture recurred after 15 and 18 months, respectively.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1432-2161
    Keywords: Key words Osteochondroma ; Chondroma ; Extraskeletal tumor ; Soft tissue tumor ; Foot ; CT ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A case of pathologically proven extraskeletal osteochondroma is presented with magnetic resonance imaging (MRI), computed tomography (CT), bone scan and radiographic findings. The diagnosis of extraskeletal osteochondroma should be considered when a discrete, ossified mass is localized in the soft tissues of the distal extremities. Nomenclature surrounding this entity is controversial and is discussed.
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  • 18
    ISSN: 1432-2161
    Keywords: Key words Chondroblastoma ; malignant ; recurrent ; p53 mutation ; Aneuploidy ; Pelvis ; Femur ; Xray ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We report a rare case of malignant chondroblastoma, which presented in a 47-year-old man as a recurrent tumor, 18 years following wide excision of a typical pelvic chondroblastoma. Radiologic studies of the recurrent tumor showed a large, lytic, destructive lesion of the right pelvic bones and femur, with a pathologic fracture of the latter, a large pelvic soft tissue mass, and multiple pulmonary metastases. Biopsy tissue showed typical features of chondroblastoma, but also increased nuclear atypia, hyperchromasia, and pleomorphism, compared to the original tumor, and, most significantly, abnormal mitotic figures. Immunohistochemical studies of the recurrent tumor revealed p53 mutation and extensive proliferative activity, and flow cytometric studies showed DNA aneuploidy, none of which was present in the original tumor. The patient received chemotherapy and radiation, but died of disease eight months after presentation. We also review chondroblastoma in general, to assign this unusual lesion to a tumor subtype.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 28 (1999), S. 703-709 
    ISSN: 1432-2161
    Keywords: Key words Proliferative myositis ; Childhood ; Lumbar muscles ; Ossification ; X-ray ; CT ; MRI ; PET
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A case of proliferative myositis in the lumbar paraspinal muscles in a 14-year-old boy is presented. Imaging investigations including plain radiograph, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), bone scan and positron emission tomography (PET) were suggestive of an inflammatory process such as myositis ossificans. The diagnosis was made by incisional biopsy. More pronounced edema, more muscle fiber necrosis and a higher cellularity were found compared to adult cases. The karyotype of the lesion was normal. Clinically, the mass disappeared spontaneously. After 24 months, asymptomatic bridging ossification between the third and fourth lumbar vertebrae was noted.
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  • 20
    ISSN: 1432-2161
    Keywords: Key words Bone tumor ; Chondrosarcoma ; CT ; Magnetic resonance imaging ; Tumor of the ankle ; Tumor of the foot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The foot is an uncommon location for chondrosarcoma. The presentation, diagnosis, pathological findings, surgical treatment and follow-up of three patients with chondrosarcoma in this rare location are presented. Though nonspecific, MR imaging findings were of aid in the diagnosis and treatment planning of these patients. If the diagnosis of this tumor is rapidly made, a tumor excision instead of limb amputation may be sufficient treatment at surgery.
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Skeletal radiology 28 (1999), S. 159-162 
    ISSN: 1432-2161
    Keywords: Key words SAPHO syndrome ; CT ; Parosteal osteosarcoma ; Sternoclavicular joints
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Considerable attention has been paid in the past 10 years to the radiological spectrum of disease entities belonging to the SAPHO syndrome. We report an unusual case presenting with an extra-axial (femoral) lesion, prior to description of this syndrome, which was radiologically and histologically mistaken for a parosteal osteosarcoma. Nineteen years later, a further lesion developed in the scapula together with the typical sternoclavicular manifestations, at which stage the correct diagnosis of SAPHO syndrome was established.
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  • 22
    ISSN: 1432-2307
    Keywords: Key words Peroxisomes ; Hepatocellular tumors ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A significant reduction of catalase activity, a peroxisomal marker enzyme, occurs in human hepatic neoplasias, but no information is available on other peroxisomal proteins. We have studied by means of immunohistochemistry four specific proteins of peroxisomes (catalase and three enzymes of lipid β-oxidation) in human hepatocellular tumors of various differentiation grades from adenoma to anaplastic carcinoma. In all tumors, except the adenomas, the tumor cells contained fewer peroxisomes than extrafocal hepatocytes and the reduction of antigenic sites in the tumor types generally correlated with the degree of tumor dedifferentiation as assessed by classical histopathological criteria. Two poorly differentiated tumors had no detectable peroxisomes at all. There were no major differences in the intensities of the immunocytochemical staining for all four studied peroxisomal antigens in different tumors, suggesting that the neoplastic transformation affects the biogenesis of the entire organelle and not merely the individual peroxisomal enzyme proteins. Some tumors exhibited a distinct peripheral distribution of peroxisomes. In cases with associated liver cirrhosis, the hepatocytes in the adjacent liver showed marked peroxisome proliferation, forming large perinuclear aggregates, occupying occasionally the entire cytoplasm. Taken together, our observations indicate that peroxisomes are significantly altered in both hepatocellular tumors and liver cirrhosis and, thus, could be responsible for some of the metabolic derangements observed in those disease processes.
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  • 23
    ISSN: 1432-2307
    Keywords: Key words p21 ; p53 ; Colon ; Immunohistochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The WAF1/CIP1 gene product, p21, an inhibitor of cyclin-dependent kinases, is a critical downstream effector in the p53 pathway. The expression of p21 in human neoplasms is heterogeneous, and may be related to p53 functional status. We evaluated p21 immunoreactivity in 103 colorectal carcinomas (CC) in relation to the p53 gene and protein alterations and clinico-pathologic parameters. High p21 expression (more than 10% reactive cells) was seen in 39% of cases. p21 staining was heterogeneous and often detected in clusters of tumour cells; in some tumours p21 staining was more pronounced in superficial areas. No relation was seen between p21 immunoreactivity and site of the tumours (right vs left), TNM stage and grade. p21 expression was related to p53 status as evaluated with IHC or with SSCP analyses, low p21 expression usually being associated with p53 protein overexpression (P=0.048) and p53 gene alteration (P=0.005). The strongest associations were seen when the combined p53/p21 immunophenotype was compared with p53 gene alterations (P=0.0002). These data support the hypothesis that p21 expression in CC is mainly related to p53 functional status, suggesting that p21 expression could be an interesting adjunct in the evaluation of the functional status of the p53 pathway in CC.
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  • 24
    ISSN: 1434-0879
    Keywords: Key words Alpha-1-microglobulin ; Calcium oxalate ; Crystallization ; ELISA ; Human ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the past few years, alpha-1-microglobulin (α1m) has been copurified from human urine with bikunin, a potent inhibitor of calcium oxalate (CaOx) crystallization in vitro. In this study, we have purified α1m without bikunin contamination and investigated its possible role in CaOx crystallization by in vitro and in vivo studies. Alpha-1m was purified with an anti-α1m antibodies CNBr-activated sepharose column. Two molecular species of α1m of respectively 30 and 60 kDa were purified. For each protein, two blots of 30 and 60 kDa cross-reacted with anti-α1m antibodies, suggesting that these two forms were derived one from the other. Both protein species inhibited CaOx crystallization in a dose-dependent manner in two in vitro tests. In the first test, the presence of α1m of 30 kDa (8 μg/ml) in a medium containing 0.76 mM CaCl2 (with 45Ca) and 0.76 mM Ox(NH4)2 inhibited CaOx crystallization by 38% as estimated by supernatant radioactivity after 1 h of agitation. In the second test, CaOx kinetics were examined for 3 to 10 min in a turbidimetric model at 620 nm. The presence of α1m of 30 kDa in a medium containing 4 mM CaCl2 and 0.5 mM Na2Ox inhibited CaOx crystallization by 41.5%, as estimated by the slope modification of turbidimetric curve. Alpha-1m can be considered as another inhibitor of urinary CaOx crystal formation, as shown by the present in vitro studies. Using an ELISA assay, we found that urinary α1m concentration was significantly lower in 31 CaOx stone formers than in 18 healthy subjects (2.95 ± 0.29 vs 5.34 ± 1.08 mg/l respectively, P = 0.01). The decreased concentration of α1m in CaOx stone formers could be responsible in these patients, at least in part, for an increased risk of CaOx crystalluria.
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  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 199 (1999), S. 45-56 
    ISSN: 1432-0568
    Keywords: Key words Skin ; Proteoglycan ; Development ; Human ; Fetal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The extracellular matrix of human fetal skin differs substantially from that of adult skin. Fetal skin contains sparse amounts of fibrillar collagen enmeshed in a highly hydrated amorphous matrix composed of hyaluronan and sulfated proteoglycans. Both fetal and adult skin contain two major interstitial proteoglycans that are extracted by chaotrophic agents and detergents. These are the large chondroitin sulfate proteoglycan versican and the small dermatan sulfate proteoglycan decorin. For this study, proteoglycans extracted from fetal and adult skin were compared on Western blots to determine the relative amounts of versican. Decorin present in the same samples provided an internal standard for these studies. Fetal skin differed from adult skin in that it contained a significantly higher proportion of versican than did adult skin. Immunohistochemical studies compared early-fetal with mid-fetal skin and found that versican was a significant component of the interstitial extracellular matrix at both of these stages of skin development. However, by the mid-fetal period, interstitial versican became restricted to the upper half of the dermis, although versican also continued to be highly expressed around hair follicles, glands, and vasculature in the lower half of the dermis. Fetal skin extracts differed from an adult skin extract by the presence of a 66-kDa protein immunologically related to versican and by the absence of a 17-kDa core protein of a proteoglycan related to decorin. Both of these molecular species may represent degradation products of their respective proteoglycans. Monoclonal antibodies which detect epitopes in native chondroitin sulfate glycosaminoglycan chains recognized versican extracted from fetal skin. However, the tissue distribution of these antigens did not entirely conform to that for versican core protein, suggesting that versican in different regions of the skin may be substituted with glycosaminoglycan chains with different microchemistries. The results of these studies indicate that human fetal skin is structurally different from adult skin in terms of both the distribution and the composition of the large, aggregating chondroitin sulfate proteoglycan versican.
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  • 26
    ISSN: 1432-0533
    Keywords: Key words Amantadine ; Human ; N-methyl-d-aspartate ; Phencyclidine ; Postmortem brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Low doses of N-methyl-d-aspartate (NMDA)-type glutamate receptor antagonists induce morphological alterations in neurons of the cingulate gyrus and retrosplenial cortex of the rat. Neuronal cell death may result at higher doses. These effects are a major concern with regard to the introduction of new NMDA receptor antagonists into clinical trials. Amantadine is an uncompetitive NMDA receptor antagonist, which has been in clinical use for many years. In the present study we have looked for possible morphological alterations like necrosis in postmortem human brain tissue of patients previously treated with amantadine. Formalin-fixed tissue samples were taken from the hippocampus, cingulate gyrus, and retrosplenial cortex of 8 patients on previous amantadine medication and of 11 controls. Histopathological examination of sections was performed blind. All brains except one revealed either nonspecific age-related or cerebrovascular changes or other neurodegenerative disorders including Alzheimer’s, Parkinson’s or Lewy body disease. In conclusion, histopathological examination of the hippocampus, retrosplenial cortex, and cingulate gyrus of human brain did not reveal changes suggested to be specific for previous amantadine treatment.
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  • 27
    ISSN: 1432-0533
    Keywords: Key words Purkinje cell ; Cerebellum ; Development ; Inositol 1 ; 4 ; 5-triphosphate type 1 receptor ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Immunohistochemical analyses were carried out on the Purkinje cells from 21 autopsied fetal and early postnatal normal cerebella using a monoclonal antibody against the inositol 1, 4, 5-triphosphate type 1 receptor (IP3R1) as a cytochemical marker of Purkinje cells. In normal adult cerebella used as positive controls, the cell bodies, axons, and dendrites, including spiny branchlets of the Purkinje cells, were specifically stained by the antibody. In the fetal cerebella examined, the IP3R1 immunoreactivity was first detected in the soma of multilayered cells just beneath the molecular layer at 16 weeks of gestation. The IP3R1 immunoreactivity gradually increased in area of positive staining from soma to dendrites and spiny branchlets, and the dendritic outgrowth rapidly progressed during 6 months after birth. The Purkinje cell maturation was more advanced in the vermis than in the hemisphere, more in the posterior lobe than in the anterior lobe, and more at the bottom of the folia than at the top. Partial absence of the Purkinje cells in the cerebellar cortex was observed in three cases. Heterotopias including Purkinje cells were often noted in the cerebellar white matter in five cases.
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  • 28
    ISSN: 1432-069X
    Keywords: Key words Chronic diabetic wounds ; Human ; fibroblasts ; Wound healing ; Cell culture ; Proliferation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Patients with diabetes mellitus experience impaired wound healing often resulting in chronic foot ulcers. Hospital discharge data indicate that 6–20% of all diabetic individuals hospitalized (mostly with type 2 diabetes) have a lower extremity ulcer. Maintaining glucose levels at acceptable levels (below 10 mmol/l) is considered to be an important part of the clinical treatment, but the exact mechanism by which diabetes delays wound repair is not yet known. We studied this phenomenon by determining the potential of fibroblasts isolated from the ulcer sites of four patients with non-insulin-dependent diabetes mellitus to proliferate in vitro. Controls were fibroblasts isolated from normal skin of the upper leg of five healthy age-matched volunteers and of six non-insulin-dependent diabetes patients. Proliferative capacity was analysed by evaluation of plates after trypsinization and [3H]thymidine incorporation. Fibroblast morphology was studied by light and transmission electron microscopy. Diabetic ulcer fibroblasts, measured by [3H]thymidine incorporation, proliferated significantly more slowly than the nonlesional control fibroblasts (P 〈 0.00047) and age-matched control fibroblasts (P 〈 0.00003). After culturing the fibroblasts for a prolonged period in high-glucose (27.5 mM) and low-glucose (5.5 mM, i.e. physiological) medium, this difference in proliferation rate between diabetic ulcer fibroblasts and nonlesional diabetic fibroblasts remained (P 〈 0.0001 for high-glucose and P 〈 0.0009 for low-glucose on day 7). Fibroblast proliferation in all three groups was slightly lower in high-glucose than in low-glucose medium, although not significantly at any time-point. Light microscopy showed diabetic ulcer fibroblasts to be large and widely spread. Transmission electron microscopy of cultured diabetic ulcer fibroblasts and nonlesional diabetic skin fibroblasts revealed a large dilated endoplasmic reticulum, a lack of microtubular structures and multiple lamellar and vesicular bodies. These results show a diminished proliferative capacity and abnormal morphology of fibroblasts derived from diabetic ulcers of non-insulin-dependent diabetes patients.
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  • 29
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    Archives of dermatological research 291 (1999), S. 247-252 
    ISSN: 1432-069X
    Keywords: Key words T cell activation ; Nickel ; Human ; Interferon-gamma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Contact hypersensitivity to nickel is the most common form of allergic contact dermatitis. To gain insight into the induction of this frequent disease, T cell reactivity towards nickel was investigated in “nonallergic” individuals defined as those with no skin manifestations and a negative patch test towards NiSO4. Surprisingly, we found that nickel induced proliferation of peripheral blood mononuclear cells (PBMC) from 16 of 18 adult individuals tested. This activation was specific, and no stimulation of PBMC was observed using control stimulants at equimolar concentrations. Furthermore, the NiSO4-induced activation required the presence of professional antigen-presenting cells. To describe the functional capacity of the nickel-inducible T cells, cytokine release was investigated in both nickel-allergic and nonallergic individuals. The T cells from both groups released interferon-γ but no interleukin-4 upon stimulation with nickel, suggesting that the functional capacities of these cell populations were similar in nickel-allergic and nonallergic individuals. Thus, at this level, no qualitative differences could be demonstrated between T cells obtained from nickel-allergic and nonallergic individuals.
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  • 30
    ISSN: 1432-069X
    Keywords: Key words ORS cells ; Melanocytes ; Human ; Organotypic cultures ; Melanosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Because outer root sheath (ORS) cells are valuable substitutes for interfollicular epidermal keratinocytes, we wanted to determine whether epidermal equivalents generated from ORS cells and containing cultured melanocytes can serve as an in vitro model for skin pigmentation. In such epidermal equivalents prepared with ORS cells and melanocytes from donors of phototypes II, III and VI, a stratified epithelium resembling normal epidermis developed within 14 days, as documented by histological, ultrastructural (e.g. basement membrane-like structure, keratohyalin granules, keratinosomes) and immunohistochemical (e.g. keratins, integrins, gp80, involucrin, filaggrin) criteria. The melanocytes were localized in the basal layer and accounted for 10% of the total cell number. Heavily pigmented melanocytes from black donors contained regular melanosomes in all stages of maturation, whereas melanocytes derived from white donors contained predominantly melanosomes of stages I and II. Melanosome-laden dendrites were readily detected extending from the heavily pigmented melanocytes, while they were less conspicuous in melanocytes from white donors. The extent of melanosome transfer was independent of the racial origin of the ORS cells. Melanosomes could also be transferred “through racial barriers”. Melanosomes, mainly of stages III and IV, were detected in the ORS cells, being distributed either as single or compound melanosomes, again irrespective of the racial origin of the ORS cells. In conclusion, pigmented epidermal equivalents generated from ORS cells offer practical advantages over other in vitro pigmentation models: (1) the ORS cells are easily and repeatedly available from any donor regardless of age; (2) primary cultures of ORS cells are free of contaminating melanocytes, a bias if using interfollicular epidermal keratinocytes; (3) a high degree of epidermal differentiation is maintained for 3 weeks in fully defined medium, enabling labelling and stimulation experiments to be performed and compounds interfering with melanin pigmentation to be tested.
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  • 31
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    Immunogenetics 49 (1999), S. 438-445 
    ISSN: 1432-1211
    Keywords: Key words PA28 ; Proteasome ; Gene structure ; Evolution ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Two proteasome activators PA28α and β, which have been implicated in antigen processing for loading class I MHC molecules, are synthesized in response to Ifn-γ. The human genes encoding these activators (PSME1 and PSME2, respectively) were analyzed by sequencing. Each gene comprised 11 exons, consistent with gene duplication during vertebrate evolution. The intron/exon organization of both genes was highly conserved, the major difference being the absence of the exon encoding the lysine and glutamic acid-rich 'KEKE' motif in PA28β. Two other genes of relevance to the immune system were located close to those for PA28 at 14q11.2 including ISGF3G, a protein involved in transcription after IFNα signalling. These sequences were also characterized.
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  • 32
    ISSN: 1432-1211
    Keywords: Key words NK cells ; Human ; Surface molecule ; Lectin superfamily ; NK gene complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Natural killer (NK) cells constitute the third major population of lymphocytes. They possess the inherent capacity to kill various tumor and virally infected cells and mediate the rejection of bone-marrow grafts in lethally irradiated animals. A large family of NK cell receptors belong to the C-type lectin superfamily and are localized to the NK gene complex on Chromosome (Chr) 6 in the mouse and Chr 12 in the human. Genes in the NK gene complex encode type II receptors and examples include the families of NKR-P1, Ly-49, and NKG2 receptors. Examples of other C-type lectin-like NK cell receptors that occur as individual genes are CD94, CD69, and AICL. Here we report the molecular characterization and chromosomal mapping of a human lectin-like transcript (LLT1) expressed on NK, T, and B cells and localized to the NK gene complex within 100 kilobases of CD69. The cDNA encodes a predicted protein of 191 amino acid residues with a transmembrane domain near the N-terminus and an extracellular domain of 132 amino acid residues with similarity to the carbohydrate recognition domain of C-type lectins. The predicted protein of LLT1 shows 59 and 56% similarity to AICL and CD69, respectively. The predicted protein does not contain any intracellular ITIM motifs, suggesting that LLT1 may be involved in mediating activation signals.
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  • 33
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    European radiology 9 (1999), S. 208-210 
    ISSN: 1432-1084
    Keywords: Key words: Muscles ; diseases ; Neoplasms ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Skeletal muscle is one of the most unusual sites of metastasis from any malignancy. We report a patient with rapidly progressive contractures due to metastatic infiltration of a carcinoma of unknown origin into the skeletal muscle. This 61-year-old man presented with a 1-month history of rapidly evolving, painful restriction of mobility of his right arm and his legs. Computed tomography showed diffuse metastatic nodules in all muscles, particularly in the hip abductors. Muscle biopsy revealed extensive infiltration of the muscle with carcinoma cells.
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  • 34
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    European radiology 9 (1999), S. 336-343 
    ISSN: 1432-1084
    Keywords: Key words: Cryptorchidism ; Scrotum ; US ; CT ; MRI ; Testis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Imaging evaluation of the patient with a non-palpable testis has evolved over recent decades. The rational explanation of imaging in these patients requires a clear understanding of the various causes of a non-palpable testis, and an appreciation of the utility and limitations of the available imaging modalities. This review describes the classification of non-palpable testis and discusses the role of modern imaging in evaluation. In particular, the relative accuracies of ultrasound, CT and MRI is reviewed.
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  • 35
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    Experimental brain research 128 (1999), S. 539-542 
    ISSN: 1432-1106
    Keywords: Key words Silent period ; Transcranial magnetic stimulation ; Motor cortex ; Epidural recordings ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We investigated the nature of the silent period (SP) following transcranial magnetic stimulation by recording corticospinal volleys in a patient with implanted cervical epidural electrodes. Single suprathreshold test stimuli and paired stimuli at interstimulus intervals (ISIs) of 50–200 ms were delivered while the subject maintained a constant background contraction. The silent period duration from a single test stimulus was 357±62 ms. The test motor-evoked potentials were markedly reduced at all the ISIs tested. The I (indirect) waves induced by the test stimulus were largely unchanged at an ISI of 50 ms, suggesting that there was little change in motor cortex excitability. However, the corticospinal volleys, especially the late I waves, were substantially reduced at ISIs of 100 ms, 150 ms, and 200 ms. Our findings suggest that the early part of the SP is mainly due to spinal mechanisms, while the late part of the SP is related to reduced motor cortex excitability.
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  • 36
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    Experimental brain research 128 (1999), S. 550-556 
    ISSN: 1432-1106
    Keywords: Key words Selective attention ; Kinematics ; Human ; Visual pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In solving the selection-for-action problem, it is believed that attentional mechanisms enable dominance of target over non-target objects. However, under some conditions, information from non-target objects ”interferes” with the action to a relevant target. We investigated the possibility that this interference may result when the irrelevant object activates a specific subset of visuomotor pathways. Participants reached to grasp three-dimensional stimuli while actively attending to a nearby flanker object. The means by which the flanker was presented was manipulated. This relevant object was illuminated either abruptly or gradually. The parvocellular pathway in early visual processing is equally activated in both conditions. The magnocellular pathway is strongly activated by abrupt presentation and weakly activated with gradual presentation of the flanker object. Kinematics of the reach-to-grasp action to the target showed signs of interference only in the sudden illumination condition. This suggests a dissociation between dorsal and ventral cortical streams in terms of relevance for action. Our data suggests that this effect is not due to early visual-pathway differences, but instead reveals a property of a transient object-based visual attention mechanism.
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  • 37
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    Experimental brain research 124 (1999), S. 1-7 
    ISSN: 1432-1106
    Keywords: Key words Temporal cortex ; Connectivity ; Human ; Interhemispheric transfer ; Talairach coordinates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The human anterior commissure is believed, by extrapolation from data obtained in macaque monkeys, to convey axons from the temporal and orbitofrontal cortex. Reports of interhemispheric transfer and sexual dimorphism related to the anterior commissure, however, make more precise data on the human anterior commissure desirable. We investigated the connectivity of the human anterior commissure in six adults (male and female) that had circumscribed hemispheric lesions in temporal, frontal, parietal or occipital cortices or in infrapallidal white matter using the Nauta for anterogradely degenerating axons. Axons originating in the inferior part of temporal or occipital lobes, occipital convexity and possibly central fissure and prefrontal convexity were found to cross the midsagittal plane in the anterior commissure. The largest contigent of commissural axons originated in the inferior part of the temporal lobe; it displayed a roughly topographic organization, preferentially running through the inferior part of the commissure. The inferior temporal contigent seemed to reach homotopic and heterotopic targets in the opposite hemisphere. Among the latter were the amygdala and possibly the orbitofrontal cortex. The present data suggest that the human anterior commissure conveys axons from much larger territories than expected from work on non-human primates. Similarly to the human and non-human primate corpus callosum, the anterior commissure is roughly topographically organized and participates in heterotopic connectivity.
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  • 38
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    Experimental brain research 126 (1999), S. 200-204 
    ISSN: 1432-1106
    Keywords: Key words Motor development ; Anticipatory postural adjustments ; Bimanual coordination ; Children ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Anticipatory postural adjustments (APA) are needed to perform a movement without perturbing posture. We investigated the development of APA in 3- to 4-year-old children during a bimanual load-lifting task. The task required maintaining a stable elbow position despite imposed or voluntary unloading of the forearm. Although children can compensate the consequences of unloading by using APA, their performance did not reach an adults’ level. In addition, children showed high intra-individual variability in the voluntary situation, revealed by the coexistence of both adult-like and immature patterns in kinematic and electromyographic data. In conclusion, the present study reports that APA, associated with a bimanual load-lifting task, are still being set up in 3- to 4-year-old-children. The intra-individual variability should decrease with age and be associated with a progressive mastering of the timing parameters characterizing APA.
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  • 39
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    Experimental brain research 124 (1999), S. 273-280 
    ISSN: 1432-1106
    Keywords: Key words Vestibular system ; Posture control ; Balance ; Cross-spectral analysis ; Coherency ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Galvanic vestibular stimulation serves to modulate the continuous firing level of the peripheral vestibular afferents. It has been shown that the application of sinusoidally varying, bipolar galvanic currents to the vestibular system can lead to sinusoidally varying postural sway. Our objective was to test the hypothesis that stochastic galvanic vestibular stimulation can lead to coherent stochastic postural sway. Bipolar binaural stochastic galvanic vestibular stimulation was applied to nine healthy young subjects. Three different stochastic vestibular stimulation signals, each with a different frequency content (0–1 Hz, 1–2 Hz, and 0–2 Hz), were used. The stimulation level (range 0.4–1.5 mA, peak to peak) was determined on an individual basis. Twenty 60-s trials were conducted on each subject – 15 stimulation trials (5 trials with each stimulation signal) and 5 control (no stimulation) trials. During the trials, subjects stood in a relaxed, upright position with their head facing forward. Postural sway was evaluated by using a force platform to measure the displacements of the center of pressure (COP) under each subject’s feet. Cross-spectral measures were used to quantify the relationship between the applied stimulus and the resulting COP time series. We found significant coherency between the stochastic vestibular stimulation signal and the resulting mediolateral COP time series in the majority of trials in 8 of the 9 subjects tested. The coherency results for each stimulation signal were reproducible from trial to trial, and the highest degree of coherency was found for the 1- to 2-Hz stochastic vestibular stimulation signal. In general, for the nine subjects tested, we did not find consistent significant coherency between the stochastic vestibular stimulation signals and the anteroposterior COP time series. This work demonstrates that, in subjects who are facing forward, bipolar binaural stochastic galvanic stimulation of the vestibular system leads to coherent stochastic mediolateral postural sway, but it does not lead to coherent stochastic anteroposterior postural sway. Our finding that the coherency was highest for the 1- to 2-Hz stochastic vestibular stimulation signal may be due to the intrinsic dynamics of the quasi-static postural control system. In particular, it may result from the effects of the vestibular stimulus simply being superimposed upon the quiet-standing COP displacements. By utilizing stochastic stimulation signals, we ensured that the subjects could not predict a change in the vestibular stimulus. Thus, our findings indicate that subjects can act as ”responders” to galvanic vestibular stimulation.
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  • 40
    ISSN: 1432-1106
    Keywords: Key words Locomotion ; Load ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Prior work from mammals suggests that load experienced by extensor muscles of the hindlimbs (i.e. Duysens and Pearson 1980; Pearson and Collins 1993; Fouad and Pearson 1997) or cutaneous afferents from the plantar surface of the foot (Duysens and Pearson 1976; Guertin et al. 1995) enhances activity in extensor muscles during the stance phase, and delays the onset of flexor activity associated with the swing phase. The presumed functional significance of this phenomenon is that extensor activity of the supporting limb during walking can: (a) reinforce the supporting function in proportion to the load experienced, and (b) prolong the stance phase until unloading of the limb has occurred. Whether a similar functional role exists for load-sensitive afferents during walking in the human is unknown. In this study, the effect of adding or removing a substantial load (30% of body weight) at the centre of mass was studied in healthy adult human subjects. Loads were applied near the centre of mass to avoid the need for postural adjustments which might confound the interpretation of the results. Subjects walked on a treadmill with either: (a) a sustained increase or decrease in load, or (b) a sudden unexpected increase or decrease in load. In general, subjects responded to the changes in load by changing the amplitude of the extensor electromyographic (EMG) bursts. For example, with sudden unexpected additions in load, the average increase in amplitude was 40% for the soleus across the stance phase, and 134% for the quadriceps during the early part of the stance phase. Extensor EMGs increased with both sustained and sudden increases in load. Extensor EMG durations also increased (average increase in duration of 4% for soleus with sudden loading, and 7% for sustained loading). Cycle duration hardly changed (average increase of 0.5% with both sudden and sustained loading). These results differ from those of infants subjected to a similar perturbation during supported walking. A large change in timing (i.e. an increase in the duration of the stance phase by 30% and the step cycle by 28%) was seen in the infants, with no change in the amplitude of the EMG burst (Yang et al. 1998). These results suggest that the central nervous system can control the timing and amplitude of extensor EMG activity in response to loading independently. Maturation of the two components most likely occurs independently. In the adult, independent control of the two components may provide greater flexibility of the response.
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  • 41
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    Experimental brain research 126 (1999), S. 235-251 
    ISSN: 1432-1106
    Keywords: Key words Motor learning and memory ; Perseveration ; Prefrontal cortex ; Reversal learning ; Basal ganglia ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The ability to inhibit previously learned visuomotor associations is essential for efficient learning of novel behaviors. While the neural basis of the system that might control interactions between competing motor memories is not known, it has been demonstrated that animals with ventral and orbital prefrontal cortex (PFC) deficits have particular difficulties in learning to withhold responses to previously conditioned sensory stimuli. Here we measured regional cerebral blood flow (rCBF), using positron emission tomography, during learning of a novel motor task that required inhibition of a previously learned motor memory. Subjects (n=24) learned reaching movements in a force field (field A). After a variable time interval, some subjects (n=15) learned to reach in a field with a reversed pattern of forces (field B). When the time interval was short (10 min), learning in field B was coincident with a reactivation of regions that had become initially activated during learning in field A: the left putamen and bilaterally in the dorsolateral PFC. Behaviorally, this was accompanied with perseveration that lasted for hundreds of movements, suggesting an instantiation of the internal model for field A during learning in field B. Neither the reactivation nor the perseveration were observed in a different group of subjects that learned field B at 5.5 h. We found that the regions which significantly differentiated the two groups during learning of B were in the ventrolateral PFC (bilaterally): there were sharp decreases in rCBF here in the 5.5 group but not in the 10-min group. At 5.5 h motor learning again involved the striatum, but this time in the left caudate. Neither the caudate nor the ventral PFC had exhibited learning-related activity in field A. Instead, they showed changes in rCBF during the reversal of the learning problem when the previously acquired motor memory was successfully gated. The results demonstrate that: (1) perseveration of a competing motor memory may be linked to reactivation of the neural circuit that participated in acquiring that memory, and (2) the ventral PFC may play an important role in the inhibitory control of the competing motor memory.
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  • 42
    ISSN: 1432-1106
    Keywords: Key words Corpus callosum ; Interhemispheric transfer ; Positron emission tomography ; Split brain ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We studied with PET the intra- and interhemispheric pathways subserving a simple, speeded-up visuomotor task. Six normal subjects and one patient with a complete section of the corpus callosum (M.E.) underwent regional cerebral blood flow (rCBF) measurements under conditions of lateralized tachistoscopic visual presentations in a simple manual reaction time paradigm. Confirming previous behavioural findings, we found that on average crossed hand and/or hemifield conditions, i.e. those requiring an interhemispheric transfer of information, yielded a longer RT than uncrossed conditions. This difference (0.7 ms) was dramatically larger (45.6 ms) in the callosum-sectioned patient M.E. In normal subjects the cortical areas selectively activated in uncrossed and crossed conditions were different. In the former condition, most activation foci were anterior to the ventral anterior commissure (VAC) plane, whereas in the latter there was a prevalent parietal and occipital activation. This shows that a simple model in which the cortical visuo-motor pathways are similar in the intra- and the interhemispheric condition, with an extra callosal route for the latter, is too simplistic. Furthermore, these results suggest that the bulk of visuomotor interhemispheric transfer takes place through the widespread callosal fibres interconnecting the parietal cortices of the two hemispheres. The pattern of activation in the two crossing conditions was markedly different in M.E., in whom interhemispheric transfer might take place via his intact anterior commissure or subcortical commissures.
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  • 43
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    Experimental brain research 125 (1999), S. 43-49 
    ISSN: 1432-1106
    Keywords: Key words Proprioception ; Visual localization ; Visual context ; Multisensory integration ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In a previous study we investigated how the CNS combines simultaneous visual and proprioceptive information about the position of the finger. We found that localization of the index finger of a seen hand was more precise (a smaller variance) than could reasonably be expected from the precision of localization on the basis of vision only and proprioception only. This suggests that, in localizing the tip of the index finger of a seen hand, the CNS may make use of more information than proprioceptive information and visual information about the fingertip. In the present study we investigate whether this additional information stems from additional sources of sensory information. In experiment 1 we tested whether seeing an entire arm instead of only the fingertip gives rise to a more precise proprioceptive and/or visual localization of that fingertip. In experiment 2 we checked whether the presence of a structured visual environment leads to a more precise proprioceptive localization of the index finger of an unseen hand. In experiment 3 we investigated whether looking in the direction of the index finger of an unseen hand improves proprioceptive localization of that finger. We found no significant effect in any of the experiments. The results refute the hypothesis that the investigated effects can explain the previously reported very precise localization of a seen hand. This suggests that localization of a seen finger is based exclusively on proprioception and on vision of the finger. The results suggest that these sensory signals may contain more information than is described by the magnitude of their variances.
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  • 44
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    Experimental brain research 125 (1999), S. 139-152 
    ISSN: 1432-1106
    Keywords: Key words Reaching movements ; Direction ; Amplitude ; Initial kinematics ; Spatial variability ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The accuracy of reaching movements to memorized visual target locations is presumed to be determined largely by central planning processes before movement onset. If so, then the initial kinematics of a pointing movement should predict its endpoint. Our study examined this hypothesis by testing the correlation between peak acceleration, peak velocity, and movement amplitude and the correspondence between the respective spatial positions of these kinematic landmarks. Subjects made planar horizontal reaching movements to targets located at five different distances and along five radially arrayed directions without visual feedback during the movements.The spatial dispersion of the positions of peak acceleration, peak velocity, and endpoint all tended to form ellipses oriented along the movement trajectory. However, whereas the peaks of acceleration and velocity scaled strongly with movement amplitude for all of the movements made at the five target distances in any one direction, the correlations with movement amplitude were more modest for trajectories aimed at each target separately. Furthermore, the spatial variability in direction and extent of the distribution of positions of peak acceleration and peak velocity did not scale differently with target distance, whereas they did for endpoint distributions. Therefore, certain features of the final kinematics are evident in the early kinematics of the movements as predicted by the hypothesis that they reflect planning processes. However, endpoint distributions were not completely predetermined by the Initial kinematics. In contrast, multivariate analysis suggests that adjustments to movement duration help compensate for the variability of the initial kinematics to achieve desired movement amplitude. These compensatory adjustments do not contradict the general conclusion that the systematic patterns in the spatial variability observed in this study reflect planning processes. On the contrary, and consistent with that conclusion, our results provide further evidence that direction and extent of reaching movements are planned and determined in parallel over time.
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  • 45
    ISSN: 1432-1106
    Keywords: Key words Three-dimensional pointing ; Human ; Remembered targets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The accuracy of visually guided pointing movements decreases with speed. We have shown that for movements to a visually defined remembered target, the variability of the final arm endpoint position does not depend on movement speed. We put forward a hypothesis that this observation can be explained by suggesting that movements directed at remembered targets are produced without ongoing corrections. In the present study, this hypothesis was tested for pointing movements in 3D space to kinesthetically defined remembered targets. Passive versus active acquisition of kinesthetic information was contrasted. Pointing errors, movement kinematics, and joint-angle coordination were analyzed. The movements were performed at a slow speed (average peak tangential velocity of about 1.2 m/s) and at a fast speed (2.7 m/s). No visual feedback was allowed during the target presentation or the movement. Variability in the final position of the arm endpoint did not increase with speed in either the active or the passive condition. Variability in the final values of the arm-orientation angles determining the position of the forearm and of the upper arm in space was also speed invariant. This invariance occurred despite the fact that angular velocities increased by a factor of two for all the angles involved. The speed-invariant variability supports the hypothesis that there is an absence of ongoing corrections for movements to remembered targets: in the case of a slower movement, where there is more time for movement correction, the final arm endpoint variability did not decrease. In contrast to variability in the final endpoint position, the variability in the peak tangential acceleration increased significantly with movement speed. This may imply that the nervous system adopts one of two strategies: either the final endpoint position is not encoded in terms of muscle torques or there is a special on-line mechanism that adjusts movement deceleration according to the muscle-torque variability at the initial stage of the movement. The final endpoint position was on average farther from the shoulder than the target. Constant radial-distance errors were speed dependent in both the active and the passive conditions. In the fast speed conditions, the radial distance overshoots of the targets increased. This increase in radial-distance overshoot with movement speed can be explained by the hypothesis that the final arm position is not predetermined in these experimental conditions, but is defined during the movement by a feedforward or feedback mechanism with an internal delay.
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  • 46
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    Experimental brain research 125 (1999), S. 265-270 
    ISSN: 1432-1106
    Keywords: Key words Tendon reflexes ; Biceps femoris ; Gait ; Ia afferents ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  During gait it is generally accepted that there is a reduction in amplitude of H-reflexes as compared to standing. For short-latency stretch reflexes, however, it is less clear whether a similar reduction in reflex gain is present during locomotion. Stretches of constant amplitude are hard to produce under these circumstances and for this reason some previous studies on the biceps femoris (BF) have used ”reduced gait” in which the stimulated leg is stepping on the spot while the contralateral leg is walking on a treadmill. With this method it was possible to show that BF tendon jerk reflexes are larger at end swing and therefore are likely to contribute to the EMG burst normally occurring in that part of the step cycle when the BF is rapidly stretched. In the present study two questions were addressed: first, whether the reflex is different in size during gait compared to standing and, second, whether it is modulated in size during the gait cycle not only during reduced but also during normal gait. It was found that during both types of gait there was a general reflex depression with regard to the respective control values obtained during standing at similar EMG activity levels. In previous studies on soleus and quadriceps, discrepancies between EMG activity and reflex amplitude have been ascribed to changes in presynaptic inhibition of Ia terminals mediating the afferent volley of the reflex. Based on the data presented, this may also be true for the BF. In both normal and reduced gait the reflex was similarly modulated in size, showing a maximum at the end of swing. This similarity implies that reduced gait may be useful as an acceptable alternative for normal gait in studies on phase-dependent reflex modulation during locomotion.
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  • 47
    ISSN: 1432-1106
    Keywords: Key words Hyperventilation ; Magnetoencephalography ; Somatosensory cortex ; Auditory cortex ; Somatosensory evoked response ; Auditory evoked response ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  It is well established that voluntary hyperventilation (HV) slows down electroencephalographic (EEG) rhythms. Little information is available, however, on the effects of HV on cortical responses elicited by sensory stimulation. In the present study, we recorded auditory evoked potentials (AEPs) and magnetic fields (AEFs), and somatosensory evoked magnetic fields (SEFs) from healthy subjects before, during, and after a 3- to 5-min period of voluntary HV. The effectiveness of HV was verified by measuring the end-tidal CO2 levels. Long-latency (100–200 ms) AEPs and long-latency AEFs originating at the supratemporal auditory cortex, as well as long-latency SEFs from the primary somatosensory cortex (SI) and from the opercular somatosensory cortex (OC), were all reduced during HV. The short-latency SEFs from SI were clearly less modified, there being, however, a slight reduction of the earliest cortical excitatory response, the N20m deflection. A middle-latency SEF deflection from SI at about 60 ms (P60 m) was slightly increased. For AEFs and SEFs, the center-of-gravity locations of the activated neuronal populations were not changed during HV. All amplitude changes returned to baseline levels within 10 min after the end of HV. The AEPs were not altered when the subjects breathed 5% CO2 in air in a hyperventilation-like manner, which prevented the development of hypocapnia. We conclude that moderate HV suppresses long-latency evoked responses from the primary projection cortices, while the early responses are less reduced. The reduction of long-latency responses is probably mediated by hypocapnia rather than by other nonspecific effects of HV. It is suggested that increased neuronal excitability caused by HV-induced hypocapnia leads to spontaneous and/or asynchronous firing of cortical neurones, which in turn reduces stimulus-locked synaptic events.
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  • 48
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    European radiology 9 (1999), S. 244-249 
    ISSN: 1432-1084
    Keywords: Key words: Pancreas ; CT ; Injuries ; Surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. In order to describe the CT findings in pancreatic injury and to evaluate the sensitivity of this technique, we performed a retrospective study. During a 5-year period (1993–1997), eight patients (five males and three females; age range 10–47 years) were investigated with CT. Endoscopicretrograde cholangiopancreatography (ERCP) was obtained in two patients, pre- and intra-operatively, respectively. Among the standard laboratory tests obtained at admission, the value of serum amylase was reviewed. The imaging findings, especially those obtained with CT, were correlated with the surgical findings, when available (in seven of eight patients). At admission, diagnosis of pancreatic injury was missed at CT in three of eight patients (37.5 %); thus, the sensitivity of CT for pancreatic injury was 62.5 %. ERCP showed rupture of the pancreatic duct in the two cases in which it was performed. Serum amylase was elevated at admission in four of eight patients, resulting in a sensitivity of 50 %. After surgery, an enterocutaneous fistula developed in one case, and was managed conservatively. One patient died from brain injury. Proper implementation of the CT technique and accurate film reading is mandatory to establish the diagnosis of pancreatic contusion. No correlation between CT features and type of outcome of surgical management could be established. On retrospective review of the CT examinations, it appeared that two of the three false-negative results could have been avoided. Therefore, proper CT technique and accurate film reading are mandatory in establishing the diagnosis of pancreatic injury.
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  • 49
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    Experimental brain research 124 (1999), S. 42-52 
    ISSN: 1432-1106
    Keywords: Key words Ocular tracking ; Oculomanual coordination ; Electromyography ; Internal model ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  When the eyes and arm are involved in a tracking task, the characteristics of each system differ from those observed when they act alone: smooth pursuit (SP) latency decreases from 130 ms in external target tracking tasks to 0 ms in self-moved target tracking tasks. Two models have been proposed to explain this coordination. The common command model suggests that the same command be addressed to the two sensorimotor systems, which are otherwise organized in parallel, while the coordination control model proposes that coordination is due to a mutual exchange of information between the motor systems. In both cases, the interaction should take into account the dynamic differences between the two systems. However, the nature of the adaptation depends on the model. During self-moved target tracking a perturbation was applied to the arm through the use of an electromagnetic brake. A randomized perturbation of the arm increased the arm motor reaction time without affecting SP. In contrast, a constant perturbation produced an adaptation of the coordination control characterized by a decrease in arm latency and an increase in SP latency relative to motor command. This brought the arm-to-SP latency back to 0 ms. These results support the coordination control model.
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  • 50
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    Experimental brain research 124 (1999), S. 287-294 
    ISSN: 1432-1106
    Keywords: Key words Magnetoencephalography ; V1 cortex ; V2 cortex ; V6 complex ; Horizontal meridian ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We recorded whole-scalp magnetoencephalographic (MEG) responses to black-and-white checkerboards to study whether the human cortical responses are quantitatively similar to stimulation of the lower and upper visual field at small, 0–6°, eccentricities. All stimuli evoked strongoccipital responses peaking at 50–100 ms (mean 75 ms). The activation was modeled with a single equivalent current dipole in the contralateral occipital cortex, close to the calcarine fissure, agreeing with an activation of the V1/V2 cortex. The dipole was, on average, twice as strong to lower than to upper field stimuli. Responses to hemifield stimuli that extended to both lower and upper fields resembled the responses to lower field stimuli in source current direction and strength. These results agree with psychophysical data, which indicate lower visual field advantage in complex visual processing. Parieto-occipital responses in the putative V6 complex were similar to lower and upper field stimuli.
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  • 51
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    Experimental brain research 126 (1999), S. 289-306 
    ISSN: 1432-1106
    Keywords: Key words Motor control ; Trajectory formation ; Coordination ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The degrees of freedom problem is often posed by asking which of the many possible degrees of freedom does the nervous system control? By implication, other degrees of freedom are not controlled. We give an operational meaning to ”controlled” and ”uncontrolled” and describe a method of analysis through which hypotheses about controlled and uncontrolled degrees of freedom can be tested. In this conception, control refers to stabilization, so that lack of control implies reduced stability. The method was used to analyze an experiment on the sit-to-stand transition. By testing different hypotheses about the controlled variables, we systematically approximated the structure of control in joint space. We found that, for the task of sit-to-stand, the position of the center of mass in the sagittal plane was controlled. The horizontal head position and the position of the hand were controlled less stably, while vertical head position appears to be no more controlled than joint motions.
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  • 52
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    Experimental brain research 124 (1999), S. 469-473 
    ISSN: 1432-1106
    Keywords: Key words Form from motion ; Visual development ; Visual acuity ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The development of dynamic vision was investigated in 400 healthy subjects (200 females and 200 males) aged between 4 and 24 years. The test consisted of a computer-generated random-dot kinematogram in which a Landolt ring was briefly presented as a form-from-motion stimulus. Motion contrast between the ring and background was varied in terms of the percentage of dots moving coherently within the ring in four levels (100%, 50%, 30%, and 20%). The subject’s task was to indicate the position of a gap in the ring (left, right, top, bottom). Results show a clear increase in performance with age for all motion contrast levels, with the greatest changes for the lowest levels. Adult performance was reached at the age of 15 years. Luminance-based static acuity measured with the Landolt test was poorly correlated with acuity for its form-from-motion analogue.
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  • 53
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    Experimental brain research 124 (1999), S. 503-512 
    ISSN: 1432-1106
    Keywords: Key words Reaching movements ; Memory for positions ; Laterality ; Posture copying ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Many recent studies indicate that memory for final position is superior to memory for movement. There is ambiguity about what is meant by the term final position, however. Is it final spatial location or final posture? According to a recently proposed theory by Rosenbaum et al., which maintains that stored postures form the basis for movement planning, when people try to return to recently reached positions, they should try to adopt the postures they just occupied. An alternative view, which holds that movements are primarily planned with respect to spatial locations, predicts that subjects should tend to return to places in external space. We describe an experiment that tested these opposing predictions. The experiment relied on the notion that if people store and use postures, they should ”copy” the posture adopted with one arm to the other arm when possible. The results support this hypothesis.
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  • 54
    ISSN: 1432-1106
    Keywords: Key words Optokinetic nystagmus ; Positron emission tomography ; Visual motion ; Area V5 ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Positron emission tomography (PET) was used to address the issue of physiological changes in the cerebral cortex associated to optokinetic nystagmus (OKN) in humans. We studied regional cerebral blood flow in eight volunteers during reflexive induction of OKN by a pattern of dots moving unidirectionally (toward the left side). We used two control conditions, with subjects passively viewing either stationary or incoherently moving dots. This paradigm was designed in order to differentiate the OKN-related activations from blood flow changes related to visual motion. When compared with the stationary condition, OKN activated a set of occipital areas known to be sensitive to visual motion. Bilateral activation was found in the striate cortex (V1) and the parieto-occipital fissure, while area V5, the intraparietal sulcus, and the pulvinar were activated only in the left hemisphere. When compared with incoherent motion, OKN activated the V1 and the parieto-occipital fissure bilaterally and the right lingual gyrus, while a signal decrease was observed in the V5 region in both hemispheres. No significant signal changes were found in areas implicated in saccades or in processing vestibular information. These results indicate that processing of OKN-related information is associated with neural activity in a specific set of visual motion areas and suggest that this network can be asymmetrically activated by a strictly unidirectional stimulation. Results are also discussed in terms of the specific kinds of OKN-related information processing subserved by each area in this network.
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  • 55
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    Experimental brain research 126 (1999), S. 175-186 
    ISSN: 1432-1106
    Keywords: Key words Listing’s plane ; Vergence ; Binocular ; Eye movements ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Earlier studies have reported temporal rotation of Listing’s plane with convergence of the eyes causing torsion, which is dependent on eye elevation. The amount by which the planes rotate differs from study to study. To gain insight into the functional significance of the temporal tilt of Listing’s plane for vision, we examined whether the rotation of the plane depends on the visual conditions, namely on the stimuli driving vergence. In different conditions, accommodative vergence, disparity-vergence, combinations of disparity with accommodation or depth perception were used and the resulting rotation of Listing’s plane was measured. Our findings show, for the first time, that the relationship between convergence and Listing’s-plane temporal rotation depends on the stimuli driving vergence. When the stimulus contains only disparity cues, vergence and Listing’s plane rotate immediately and consistently among subjects. Accommodative vergence, the mutual couplings between vergence and accommodation, can influence the orientation of Listing’s plane, but they do so in a idiosyncratic way. The largest rotation was elicited by stereograms combining disparity-vergence with depth perception. These findings support the idea of a functional role of Listing’s plane rotation for binocular vision, perhaps for depth perception.
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  • 56
    ISSN: 1432-1106
    Keywords: Key words Grip force ; Force control ; Parabolic flight ; Microgravity ; Hypergravity ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In the present study, grip forces exerted against a stationary held object were recorded during parabolic flights. Such flight maneuvers induce changes of gravity with two periods of hypergravity, associated with a doubling of normal terrestrial gravity, and a 20 s period of microgravity. Accordingly, the object’s weight changed from being twice as heavy as normally experienced and weightless. Grip-force recordings demonstrated that force control was seriously disturbed only during the first experience of hyper- and microgravity, with the grip forces being exceedingly high and yielding irregular fluctuations. Thereafter, however, grip force traces were smooth, the force level was scaled to the object’s weight under normal and high-G conditions, and the grip force changed in parallel with the weight during the transitions between hyper- and microgravity. In addition, during weightlessness, when virtually no force was necessary to stabilize the object, a low force was established, which obviously represented a reasonable safety margin for preventing possible perturbations. Thus, all relevant aspects of grip-force control observed under normal gravity conditions were preserved during gravity changes induced by parabolic flights. Hence, grip-force control mechanisms were able to cope with hyper- and microgravity, either by incorporating relevant receptor signals, such as those originating from cutaneous mechanoreceptors, or by adequately including perceived gravity signals into control programs. However, the adaptation to the uncommon gravity conditions was not complete following the first experience; finer tuning of the control system to both hyper- and microgravity continued over the measurement interval, presumably with a longer observation period being necessary before a stable performance can be reached.
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  • 57
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    Experimental brain research 129 (1999), S. 156-160 
    ISSN: 1432-1106
    Keywords: Key words Optokinetic nystagmus ; Depth-from-motion ; Transparent motion ; Ambiguous ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  When two visual patterns moving in opposite directions are superimposed, they appear to be at different depths and to slide over each other. Because the stimulus does not specify the depth-order between the surfaces, this transparent motion perception is essentially ambiguous. With prolonged observation, the perceived depth-order of the two moving surfaces reverses spontaneously. In the present study, the correlation between the perceived direction of transparent motion and optokinetic nystagmus (OKN) was examined. While viewing superimposed random-dot patterns moving in opposite horizontal or vertical directions, subjects attempted to fixate the center of the stimulus, while paying attention to either the near or far depth plane, and reported any changes of the direction of surface-motion at the attended depth. Even with attention focused on a particular depth, the spontaneous reversal of transparent motion perception still occurred. This indicates that the perceptual reversal may reflect a preattentive mechanism for depth-from-motion. Furthermore, the OKN slow-phase tended to be in the same direction as the perceived motion of the surface at the attended depth. These results support the idea that the mechanisms for OKN maintenance are sensitive to perception of depth-from-motion and, therefore, cortically mediated.
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  • 58
    ISSN: 1432-1106
    Keywords: Key words Reaching movements ; Grasping movements ; Prehension ; Manual control ; Computational model ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Reaching and grasping an object can be viewed as the solution of a multiple-constraint satisfaction problem. The constraints include contact with the object with the appropriate effectors in the correct positions as well as generation of a collision-free trajectory. We have developed a computational model that simulates reaching and grasping based on these notions. The model, rendered as an animation program, reproduces many basic features of the kinematics of human reaching and grasping behavior. The core assumptions of the model are: (1) tasks are defined by flexibly organized constraint hierarchies; (2) manual positioning acts, including prehension acts, are first specified with respect to goal postures and then are specified with respect to movements towards those goal postures; (3) goal postures are found by identifying the stored posture that is most promising for the task, as determined by the constraint hierarchy, and then by generating postures that are more and more dissimilar to the most-promising stored posture until a deadline is reached, at which time the best posture that was found during the search is defined as the goal posture; (4) depending on when the best posture was encountered in the search, the deadline for the search in the next trial is either increased or decreased; (5) specification of a movement to the goal posture begins with straight-line interpolation in joint space between the starting posture and goal posture; (6) if an internal simulation of this default movement suggests that it will result in collision with an obstacle, the movement can be reshaped until an acceptable movement is found or until time runs out; (7) movement reshaping occurs by identifying a via posture that serves as a body position to which the actor moves from the starting posture and then back to the starting posture, while simultaneously making the main movement from the starting posture to the goal posture; (8) the via posture is identified using the same posture-generating algorithm as used to identify the goal posture. These processes are used both for arm positioning and, with some elaboration, for prehension. The model solves a number of problems with an earlier model, although it leaves some other problems unresolved.
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  • 59
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    Experimental brain research 127 (1999), S. 83-94 
    ISSN: 1432-1106
    Keywords: Key words Target interception ; Reaching ; Grasping ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The goal of the present study was to understand which characteristics (movement time or velocity) of target motion are important in the control and coordination of the transport and grasp-preshape components of prehensile movements during an interception task. Subjects were required to reach toward, grasp and lift an object as it entered a target area. Targets approached along a track at four velocities (500, 750, 1000 and 1250 mm/s) which were presented in two conditions. In the distance-controlled condition, targets moving at all velocities traveled the same distance. In the viewing-time-controlled condition, combinations of velocity and starting distances were performed such that the moving target was visible for 1000 ms for all trials. Analyses of kinematic data revealed that when, target distance was controlled, velocity affected all transport-dependent measures; however, when viewing time was controlled, these dependent measures were no longer affected by target velocity. Thus, the use of velocity information was limited in the viewing-time-controlled condition, and subjects used other information, such as target movement time, when generating the transport component of the prehensile movement. For the grasp-preshape component, both peak aperture and peak-aperture velocity increased as target velocity increased, regardless of condition, indicating that target velocity was used to control the spatial aspects of aperture formation. However, the timing of peak aperture was affected by target velocity in the distance-controlled condition, but not in the viewing-time-controlled condition. These results provide evidence for the autonomous generation of the spatial and temporal aspects of grasp preshape. Thus, an independence between the transport and grasp-preshape phases was found, whereby the use of target velocity as a source of information for generating the transport component was limited; however, target velocity was an important source of information in the grasp-preshape phase.
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    Experimental brain research 127 (1999), S. 207-212 
    ISSN: 1432-1106
    Keywords: Key words Attention ; Distractor interference ; Path deviation ; Horse race model ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  It has been suggested that, when movements are planned within cluttered environments, competing responses programmed to distracting stimuli are inhibited based on their relation to the action being performed. Further, as a result of this inhibition, the path of the movement made to the target object deviates away from the distractor. In contrast to the object avoidance hypothesis, the results of the present study show that, for aiming movements made in environments in which distractors are present, the path of the movement veers toward the distractor. Moreover, the effects of the distractors on the movement trajectory were independent of the direction of limb movement. These findings suggest that, when a distractor is not a potential physical barrier, a response to the distractor may be activated along with the target response and, owing to temporal advantages, cause a deviation of the movement trajectory toward the distractor.
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  • 61
    ISSN: 1432-1106
    Keywords: Key words Reach to grasp ; Human ; Perturbation ; Kinematics ; Motor control ; Parkinson’s disease ; Elderly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study assessed the adaptive response of the reach-to-grasp movement of 12 Parkinson’s disease (PD) and 12 control subjects to a simultaneous perturbation of target object location and size. The main aim was to test further the reported dysfunction of PD subjects in the simultaneous activation of movement components. Participants were required to reach 30 cm to grasp a central illuminated cylinder of either small (0.7 cm) or large (8 cm) diameter. For a small percentage of trials (20/100) a visual perturbation was introduced unexpectedly at the onset of the reaching action. This consisted of a shift of illumination from the central cylinder to a cylinder of differing diameter, which was positioned 20° to the left (n=10) or to the right (n=10). The subject was required to grasp the newly illuminated cylinder. For the Parkinson’s disease subject group, the earliest response to this ’double’ perturbation was in the parameter of peak reaching acceleration, which was on average 50 ms earlier for ’double’ perturbed than for non-perturbed trials. The grasp component response followed more than 500 ms after the earliest transport response. For the control subjects initial signs of a response to the ’double’ perturbation were seen almost simultaneously in the transport parameter of peak arm deceleration, and in the manipulation parameter of maximum grip aperture, but these changes were not evident until more than 400 ms after movement onset. These results indicate that the basal ganglia can be identified as part of a circuit which is involved in the integration of parallel neutral pathways, and which exercise flexibility in the degree to which these components are ’coupled’ functionally. With basal ganglia dysfunction the activation of integration centres that at first gate the flow of information to the parallel channels of reach and grasp seems inefficient.
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  • 62
    ISSN: 1432-1912
    Keywords: Key words Blood pressure ; Endothelium ; Human ; Mesenteric artery ; Rat ; Smooth muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: 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.
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  • 63
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    Der Radiologe 39 (1999), S. 958-964 
    ISSN: 1432-2102
    Keywords: 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
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: 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.
    Notes: 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.
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  • 64
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    Der Radiologe 39 (1999), S. 1027-1034 
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Computertomographie ; Kiefer ; Dental-CT ; Software ; Key words Mandible ; Maxilla ; Computed tomography ; Software ; Dental-CT ; Jaws ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Traditionally oral surgeons and dentists have evaluated the jaws using intraoral films and panoramic radiographs. The involvement of radiologists has been limited. In the past few years dedicated CT-software-programs developed to evaluate dental implant patients have provided a new look at the jaws. The complex anatomy is described and identified on human skulls and on axial, panoramic, and cross-sectional images. With this anatomic description Dental-CT-scans are used to demonstrate the anatomy of maxilla and the mandible. An overview of the technique of Dental-CT is provided, furthermore the radiation dose of different organs is explained. Suggestions to reduce these doses by simple modifications of the recommended procols are given.
    Notes: Zusammenfassung Die Einführung im Bereich der Computertomographiesoftware (Dental-CT) ermöglicht dem Radiologen zusätzlich zu den üblichen, von den Zahnärzten durchgeführten Röntgenuntersuchungen eine überlagerungs- und verzerrungsfreie Darstellung des Ober- und Unterkiefers. In der Implantologie ist mit dieser Darstellung eine exakte Planung möglich. Weiterhin haben sich Dünnschicht-CT-Untersuchungen auch bei der Abklärung von Zysten, Tumoren, Frakturen, tiefen Parodontitiden und retinierten Zähnen bewährt. In dieser Arbeit wird ein Überblick über die Anatomie, die Untersuchungstechnik des Dental-CT und die auftretende Strahlenbelastung gegeben. Basierend auf rezente Literaturangaben kann eine Reduktion der absorbierten Dosis bei gleichbleibender Bildqualität durch einfache Protokollmodifikationen erzielt werden.
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  • 65
    ISSN: 1432-2072
    Keywords: Key words Marijuana ; Human ; THC ; Withdrawal ; Dependence ; Tolerance ; Subjective effect ; Performance ; Food intake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Symptoms of dependence and withdrawal after the frequent administration of high doses (210 mg/day) of oral Δ9-tetrahydrocannabinol (THC) have been reported, yet little is known about dependence on lower oral THC doses, more relevant to levels attained by smoking marijuana. In a 20-day residential study, male (n = 6) and female (n = 6) marijuana smokers worked on five psychomotor tasks during the day (0915–1700 hours), and in the evening engaged in private or social recreational activities (1700–2330 hours); subjective-effects measures were completed 10 times/day, and a sleep questionnaire was completed each morning. Food and beverages were available ad libitum from 0830 to 2330 hours. Capsules were administered at 1000, 1400, 1800, and 2200 hours. Placebo THC was administered on days 1–3, 8–11, and 16–19. Active THC was administered on days 4–7 (20 mg qid) and on days 12–15 (30 mg qid). Both active doses of THC increased ratings of “High,”“Good Drug Effect,” and “Willingness to Take Dose Again” compared to baseline (days 1–3). THC also increased food intake by 35–45%, and decreased verbal interaction among participants compared to placebo baseline. Tolerance developed to the subjective effects of THC but not to its effects on food intake or social behavior. Abstinence from THC increased ratings of “Anxious,”“Depressed,” and “Irritable,” decreased the reported quantity and quality of sleep, and decreased food intake by 20–30% compared to baseline. These behavioral changes indicate that dependence develops following exposure to lower daily doses of THC than have been previously studied, suggesting that the alleviation of abstinence symptoms may contribute to the maintenance of daily marijuana use.
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  • 66
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    Psychopharmacology 141 (1999), S. 395-404 
    ISSN: 1432-2072
    Keywords: Key words Marijuana ; Dependence ; Withdrawal ; Human ; Tolerance ; Subjective effect ; Performance ; Residential laboratory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Symptoms of withdrawal after oral Δ9-tetrahydrocannabinol (THC) administration have been reported, yet little is known about the development of dependence on smoked marijuana in humans. In a 21-day residential study, marijuana smokers (n = 12) worked on five psychomotor tasks during the day (0915–1700 hours), and in the evening engaged in recreational activities (1700–2330 hours); subjective-effects measures were completed 10 times/day. Food and beverages were available ad libitum from 0830 to 2330 hours. Marijuana cigarettes (0.0, 1.8, 3.1% THC) were smoked at 1000, 1400, 1800, and 2200 hours. Placebo marijuana was administered on days 1–4 . One of the active marijuana doses was administered on days 5–8, followed by 4 days of placebo marijuana (days 9–12). The other concentration of active marijuana cigarettes was administered on days 13–16, followed by 4 days of placebo marijuana (days 17–20); the order in which the high and low THC-concentration marijuana cigarettes were administered was counter-balanced between groups. Both active doses of marijuana increased ratings of “High,” and “Good Drug Effect,” and increased food intake, while decreasing verbal interaction compared to the placebo baseline (days 1–4). Abstinence from active marijuana increased ratings such as “Anxious,”“Irritable,” and “Stomach pain,” and significantly decreased food intake compared to baseline. This empirical demonstration of withdrawal from smoked marijuana may suggest that daily marijuana use may be maintained, at least in part, by the alleviation of abstinence symptoms.
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  • 67
    ISSN: 1432-2072
    Keywords: Key words Aggression ; Tryptophan ; Serotonin ; Human ; Diet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Some studies have shown that sharp reduction of L-tryptophan (Trp) concentration in plasma results in increases in laboratory-measured aggression. Conversely, raising plasma Trp has blunted aggression. These effects are presumably due to impaired or enhanced serotonin synthesis and neurotransmission in the brain. In this study, the laboratory-measured aggressive behavior of eight men under both Trp depletion (T-) and Trp loading (T+) conditions was compared to their aggressive behavior under food-restricted control conditions (overnight fast without an amino acid beverage). Subjects were provoked by periodic subtraction of money which was attributed to a fictitious other participant, and aggression was defined as the number of retaliatory responses the subject made ostensibly to reduce the earnings of the (fictitious) other participant. Following ingestion of the T- beverage, aggressive responding was significantly elevated relative to the food-restricted control condition, and this increased aggressive behavior became more pronounced across behavioral testing sessions on a time-course which paralleled previously documented decreases in plasma Trp concentrations. In contrast, no changes were observed in aggressive responding under T+ conditions relative to food-restricted conditions. These within-subject behavioral changes under depleted plasma Trp conditions support earlier indications of a role of serotonin in regulating aggression.
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  • 68
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Human ; Self-administration ; D1 agonist ; Subjective effect ; Craving ; Cardiovascular effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rationale: Data in laboratory animals suggest that D1 receptor agonists may have potential utility for the treatment of cocaine abuse. Objective: The effects of ABT-431, a selective agonist at the dopamine D1 receptor, on the reinforcing, cardiovascular and subjective effects of cocaine were investigated in humans. Method: Nine experienced cocaine smokers (8M, 1F), participated in nine self-administration sessions while residing on an inpatient research unit: three doses of ABT-431 (0, 2, 4 mg IV) were each given in combination with three doses of smoked cocaine (0, 12, 50 mg). ABT-431 was intravenously administered over a 1-h period immediately prior to cocaine self-administration sessions. A six-trial choice procedure (cocaine versus $5 merchandise vouchers) was utilized, with sessions consisting of: (a) one sample trial, where participants received the cocaine dose available that day, and (b) five choice trials, where participants chose between the available cocaine dose and one merchandise voucher. Results: ABT-431 did not affect the number of times participants chose to smoke each dose of cocaine, but produced significant dose-dependent decreases in the subjective effects of cocaine, including ratings of “High,”“Stimulated,” dose liking, estimates of dose value, “Quality,” and “Potency.” Furthermore, there was a trend for ABT-431 (4 mg) to decrease cocaine craving. ABT-431 also increased heart rate, while decreasing systolic and diastolic pressure at each dose of cocaine. Conclusions: These data suggest that D1 agonists may have potential utility for the treatment of cocaine abuse.
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  • 69
    ISSN: 1432-2072
    Keywords: Key words Methadone maintenance treatment ; Chiral analysis ; Methadone ; Plasma ; Urine ; Abused drug ; Daily variation ; Rating scales ; Dose-adjustment ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rationale: One of the major problems in methadone maintenance treatment is to find optimal individual doses for the patients. Objective: The present study investigated whether the use of rating scales together with enantioselective analysis of l-methadone might facilitate dose adjustments in a clinical situation. Methods: Rating scales were used to evaluate subjective and objective signs of well-being in relation to plasma methadone concentrations in two groups of patients receiving methadone maintenance treatment. The first group (n = 25) was well-adjusted according to clinical observations and were satisfied with their methadone doses (86.2 ± 4.3 mg). The second group (n = 25) was in need of the methadone dose adjustment; they complained of low dosing, despite a dose level of 69.2 ± 4.0 mg/day. Results: Results indicated a significant correlation between dose and methadone concentration among dissatisfied patients only. The trough levels of d,l-methadone and l-methadone, as well as their elimination rates, were similar in the two groups of patients. There was a variable predominance of l- over d-methadone in plasma (ratio ≈1.2; range 0.7–3.6). Illicit use of drugs by the patients was related to the methadone dose and to satisfaction with the dose received. Increased illicit drug use among dissatisfied patients was successfully eliminated by raising the methadone dose. Subjective and objective ratings of the satisfied patients were quite stable throughout the evaluation period, whereas the ratings of the dissatisfied patients were unstable. These patients seemed to be more sensitive to low trough levels of methadone than the satisfied patients. Associations between the subjective and objective ratings and plasma methadone, along with background characteristics, were characterized by multiple regression analyses. The plasma concentrations of l-methadone were one of the most important explanatory variables in these analyses. Associations between well-being and methadone concentrations in plasma were stronger for l-methadone than for d,l-methadone. Conclusions: Selective measurements of the active isomer and the use of rating scales should be of clinical value when monitoring methadone maintenance treatment patients.
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  • 70
    ISSN: 1432-2072
    Keywords: Key words MDMA ; Ecstasy ; Human ; EEG ; Power ; Coherence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rationale: Despite animal studies implicating 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy) in serotonergic neurotoxicity, there is little direct evidence of changes in neural function in humans who use MDMA as a recreational drug. Objective: The present study investigated whether there is a correlation between quantitative EEG variables (spectral power and coherence) and cognitive/mood variables, and level of prior use of MDMA. Methods: Twenty-three recreational MDMA users were studied. Resting EEG was recorded with eyes closed, using a 128-electrode geodesic net system, from which spectral power, peak frequency and coherence levels were calculated. Tests of intelligence (NART), immediate and delayed memory, frontal function (card sort task), and mood (BDI and PANAS scales) were also administered. Pearson correlation analyses were used to examine the relationship between these measures and the subject’s consumption of MDMA during the previous 12-month period. Partial correlation was used to control for the use of other recreational drugs. Results: MDMA use was positively correlated with absolute power in the alpha (8–12 Hz) and beta (12–20 Hz) frequency bands, but not with the delta (1–3 Hz) or theta (4–7 Hz) bands. MDMA use was negatively correlated with EEG coherence, a measure of synchrony between paired cortical locations, in posterior brain sites thought to overly the main visual association pathways of the occipito-parietal region. MDMA use did not correlate significantly with any of the mood/cognitive measures except the card sort task, with which it was weakly negatively correlated. Conclusions: Alpha power has been shown to be inversely related to mental function and has been used as an indirect measure of brain activation in both normal and abnormal states. Reduced coherence levels have been associated with dysfunctional connectivity in the brain in disorders such as dementia, white-matter disease and normal aging. Our results may indicate altered brain function correlated with prior MDMA use, and show that electroencephalography may be a cheap and effective tool for examining neurotoxic effects of MDMA and other drugs.
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  • 71
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    Psychopharmacology 145 (1999), S. 162-174 
    ISSN: 1432-2072
    Keywords: Key words Opioid blockade ; Buprenorphine ; Naltrexone ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rationale: One therapeutic benefit of mu opioid agonist or antagonist maintenance is the resultant attenuation of the effects of illicit opioids. It is important to characterize the development and duration of opioid blockade produced by buprenorphine, a novel opioid dependence pharmacotherapy. Objective: This study characterized the ability of buprenorphine to attenuate opioid effects during treatment initiation and discontinuation compared to naltrexone and placebo. Methods: Opioid-experienced volunteers (n = 8) participated in this 10-week, inpatient, double-blind, within-subject, crossover study. Five randomized conditions [buprenorphine (2 and 8 mg, sublingually), naltrexone (25 and 100 mg, PO) and placebo] were each examined during a 2-week period; the test drug was given for 7 days followed by a 7-day placebo wash-out. Cumulative doses of hydromorphone (0, 2 and 4 mg, IM, 45 min apart) were administered thrice-weekly corresponding with treatment and wash-out days 1, 3, and 5; behavioral, physiological and pharmacokinetic measures were collected. Results: Buprenorphine alone produced dose-related prototypic agonist effects during induction (i.e., positive mood, respiratory depression, miosis); tolerance developed only to the subjective effects. Buprenorphine 2 mg partially attenuated the effects of hydromorphone, while nearly complete attenuation was observed with 8 mg that lasted up to 72 h after discontinuation. Both naltrexone doses produced complete hydromorphone blockade after a single dose; blockade of the behavioral, but not physiological, effects persisted for 5 days after discontinuation of 100 mg. Conclusions: These data suggest that 2 mg buprenorphine is a sub-therapeutic maintenance dose, both buprenorphine 8 mg and naltrexone produce immediate and efficacious opioid blockade, and adequate protection against illicit opioids may be achieved with less-than-daily dosing.
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    Psychopharmacology 145 (1999), S. 39-51 
    ISSN: 1432-2072
    Keywords: Key words Zaleplon ; Triazolam ; Benzodiazepine ; Hypnotics ; Learning ; Memory ; Abuse potential ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Zaleplon, a pyrazolopyrimidine that is under development as a hypnotic, produces its pharmacological effects at the benzodiazepine-recognition site on the GABAA benzodiazepine-receptor complex. Unlike most benzodiazepines, zaleplon binds selectively to the BZ1 (ω1) subtype of the benzodiazepine receptor. The present study compared the acute subject-rated effects, performance-impairing effects, and abuse potential of zaleplon and triazolam, a triazolobenzodiazepine hypnotic, in 14 healthy volunteers with histories of drug abuse. Zaleplon (25, 50, and 75 mg), triazolam (0.25, 0.5, and 0.75 mg) and placebo were administered orally in this double-blind, crossover study. Zaleplon and triazolam produced comparable dose-related effects on several subject-rated drug-effect questionnaires. Zaleplon and triazolam also produced comparable dose-dependent decrements on several performance tasks including balance, circular lights, digit-enter and recall, DSST, picture recall/recognition and repeated acquisition. Same-day and next-day subject-rated measures reflecting abuse potential (e.g., drug liking, good effects, and monetary street value) also suggest that zaleplon and triazolam were comparable. The only notable between-drug difference observed in the present study was that the time-action function of zaleplon differed from that of triazolam. The onset time, time to maximum drug effect, and duration of action were shorter with zaleplon than triazolam. Thus, despite its non-benzodiazepine structure and unique benzodiazepine-receptor binding profile, the behavioral pharmacological profile of zaleplon is similar to that of triazolam.
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  • 73
    ISSN: 1432-2072
    Keywords: Key words Nicotine ; Drug discrimination ; Training conditions ; Testing conditions ; Three-choice procedure ; Subjective effect ; Human ; Smoking status
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Discrimination of a drug’s interoceptive stimulus effects often depends substantially on training and testing conditions. Objectives: We examined changes in nicotine discrimination behavior in humans as a function of lowering the training dose and of varying the discrimination testing procedure. Methods: Smokers and never-smokers (n=10 each) were initially trained to discriminate 20 µg/kg nicotine by nasal spray from placebo (0) and tested on generalization of discrimination responding across a range of doses from 0 to 20 µg/kg. Each subsequently learned to reliably discriminate progressively smaller doses of nicotine from placebo until his or her threshold dose for discrimination was identified (mean=2.7 µg/kg). A repeat testing of generalization responding across 0–20 µg/kg was then conducted, using placebo and the subject’s threshold dose as training doses. Generalization testing involved both two-choice and three-choice (novel response option) quantitative procedures. Results: A significant shift to the left was seen in nicotine-appropriate responding in the two-choice procedure when the nicotine training dose was lowered (i.e. from the first to the second test of generalization). In the three-choice procedure, however, there was no such leftward shift. Instead, in never-smokers, a flattening of nicotine-appropriate responding occurred with a lowering of the training dose, while novel-appropriate responding significantly increased. The subjective effects of ”head rush” and, in never-smokers only, ”jittery” also showed a shift to the left in their relationship with nicotine generalization dose when the training dose was lowered. Conclusions: These results confirm the importance of training and testing conditions on discrimination behavior and subjective drug responses within subjects and demonstrate the utility of the novel-response, three-choice procedure for assessing qualitatively different stimulus effects of novel drug doses.
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  • 74
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    Psychopharmacology 146 (1999), S. 111-118 
    ISSN: 1432-2072
    Keywords: Key words Buprenorphine ; Heroin dependence ; Opioid dependence ; Human ; Opioid withdrawal ; Treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Administration of double the maintenance dose of buprenorphine has been shown to permit every-other-day dosing. Whether longer periods between dosing can be achieved is unknown. Objectives: To examine whether triple the maintenance dose can be administered every 72 h without opioid withdrawal or intoxication. Methods: Sixteen opioid-dependent outpatients each received three conditions (1) the maintenance dose of buprenorphine every 24 h, (2) double the maintenance dose every 48 h, and (3) triple the maintenance dose every 72 h under double-blind placebo-controlled conditions. Each conditions was imposed in a random sequence for 21–22 days. Self report and observer measures were taken at 24-h intervals. Results: No significant differences were observed on measures of opioid agonist and withdrawal effects between the dosing conditions. However, averaging effects across conditions may obscure important within-condition effects. When conditions were analyzed by individual days within a condition, several significant effects were observed. For example, 24 h after administration of triple the maintenance dose, significant effects were observed in eight opioid agonist measures. Also, 72 h after administration of triple the maintenance dose, significant effects were observed on four measures of withdrawal. Neither adverse medical reactions nor excessive opioid intoxication were observed. Conclusions: These results suggest that buprenorphine may be administered safely every 72 h by tripling the maintenance dose, with only minimal withdrawal complaints. Importantly, this 72-h dosing may permit patients to attend clinic thrice weekly without the use of take-home doses.
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  • 75
    ISSN: 1432-2072
    Keywords: Key words Alcohol effect ; Impulsivity ; Working memory ; Executive function ; High-risk ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Impulsivity is associated with increased risk for alcoholism. Alcohol also may increase impulsive behavior, although little is known about the processes underlying this effect. Objectives: This study tested a model proposing that the executive processes of working memory (WM) and conditional associative learning (CAL) modulate behavioral inhibition. Subjects had either a positive (FHP) or a negative (FHN) family history of alcoholism. Hypotheses were that alcohol would increase Go/No-Go impulsive responding but only in subjects with low working memory capacity (low-WM), low-CAL ability, or FHP for alcoholism. The model also predicted that WM and CAL modulate inhibitory responses to contingency reversal on a Go/No-Go task. Methods: A Go/No-Go learning task with a midway contingency reversal was administered to 71 FHP and 78 FHN subjects when sober and after drinking one of two moderate doses of alcohol. WM (digits backward) and CAL (conditional spatial association task) were also assessed when sober. Results: Alcohol resulted in more false alarms but only in low-WM subjects. Both WM and CAL modulated learning to inhibit behavior after contingency reversal, suggesting separate modulation mechanisms for WM and CAL. Subjects with low- capacity WM and subjects with low-capacity CAL ability had more difficulty learning response inhibition after contingency reversal. FHPs and FHNs did not differ in their response to alcohol. Conclusions: The results support our model of the modulatory role of WM and CAL in the ongoing regulation of behavioral inhibitory systems. The results also suggest that individuals with low capacity WM are more susceptible to alcohol’s effect of increasing impulsive behavior, suggesting that alcohol reduces the capacity of working memory to modulate response inhibition.
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  • 76
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    Psychopharmacology 147 (1999), S. 200-209 
    ISSN: 1432-2072
    Keywords: Key words Benzodiazepine ; Flumazenil ; Precipitated withdrawal ; Antagonist ; Physical dependence ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Preclinical studies of the benzodiazepine antagonist flumazenil (Romazicon®) have contributed to the understanding of the physical dependence associated with chronic benzodiazepine use; when administered to animals chronically pretreated with benzodiazepines, flumazenil precipitates a withdrawal syndrome. However, few controlled clinical studies have been conducted. Objectives: The objective was to characterize the effects of flumazenil in long-term users of therapeutic doses of benzodiazepines. Methods: The acute physiological, participant-rated, and observer-rated effects of intravenously administered flumazenil (1 mg/70 kg) and caffeine (300 mg/70 kg; active drug control) were evaluated in an experimental group of 13 long-term users (mean 4.6 years) of low therapeutic doses (mean 11.2 mg/day diazepam equivalent) relative to a matched group of 13 volunteers without prior exposure to benzodiazepines in a double-blind, placebo-controlled, mixed design. Results: Whereas the experimental group did not differ from the control group with respect to the effects of placebo, and both groups showed some changes in response to caffeine (e.g., increased blood pressure and anxiety scores), only the experimental group showed considerable changes in physiological measures, participant ratings (e.g., increased ratings of dizziness, blurred vision, heart pounding, feelings of unreality, pins and needles, nausea, sweatiness, noises louder than usual, jitteriness, things moving, sensitivity to touch), and observer ratings in response to flumazenil; in addition, four participants developed panic attacks. Conclusions: This study clearly demonstrates that flumazenil can precipitate symptoms commonly associated with benzodiazepine withdrawal in chronic low-dose benzodiazepine users.
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  • 77
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    Psychopharmacology 147 (1999), S. 266-273 
    ISSN: 1432-2072
    Keywords: Key words Benzodiazepine ; Lorazepam ; Human ; Memory ; Auditory priming ; Visual priming ; Explicit memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Lorazepam has been repeatedly shown to impair both explicit memory and perceptual priming, a form of implicit memory, in the visual domain. However, the effects of this benzodiazepine on priming in other perceptual domains, such as auditory priming, have never been explored. Objective:The present study investigated whether the deleterious effects of lorazepam on perceptual priming are restricted to the visual domain, or if they could be extended to the auditory domain. Methods: Thirty-two healthy volunteers were randomly assigned to two parallel groups, placebo and lorazepam 0.038 mg/kg. The drug was administered orally, following a double-blind procedure. In the same subjects, perceptual priming was assessed in the auditory and visual domains using similar word-stem completion tasks, and explicit memory was explored using a free- recall task. Results: Lorazepam markedly reduced free-recall performance for visually and auditorily presented words. Lorazepam equally impaired visual and auditory priming. In the auditory word-stem completion task, prior presentation of a word facilitated perception of its stem in the placebo group. This facilitation effect was not observed in the lorazepam group. The lorazepam-induced impairment of priming was not due to sedation or explicit contamination. Conclusion: These results indicate that the deleterious effects of lorazepam on priming are not restricted to the visual modality, but extend to the auditory modality.
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  • 78
    ISSN: 1432-1084
    Keywords: Key words: Langerhans' cell histiocytosis ; Liver ; Spleen ; CT ; Ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We present a case of Langerhans' cell histiocytosis (LCH) of the liver and spleen in an adult. The imaging features are different from those in the few previously reported cases of individual organ involvement by LCH.
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  • 79
    ISSN: 1432-1084
    Keywords: Key words: Stomach neoplasm ; Gastric lipoma ; Acute gastrointestinal hemorrhage ; Ultrasound ; CT ; MR imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We report a case of gastric lipoma which manifested with an episode of acute gastrointestinal hemorrhage. Preoperative diagnosis was based on the US, CT, and MRI findings, as the results of gastrointestinal endoscopy were inconclusive. The role of current imaging methods, and particularly of MRI, is discussed.
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  • 80
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    European radiology 9 (1999), S. 259-261 
    ISSN: 1432-1084
    Keywords: Key words: Liver neoplasms ; CT ; Fat ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Follow-up of two hepatic angiolipomas in a patient without evidence of tuberous sclerosis is reported. Initially, the lesions presented as homogenously enhancing masses, which were nearly isodense to normal liver tissue on plain CT scans. Focal nodular hyperplasia was assumed. One year later, fat was detected in the growing tumors and percutaneous core biopsy revealed hepatic angiolipomas. Natural history of these rare lesions is unknown, and this is to the best of our knowledge the first observation of fatty metamorphosis in such a benign, mesenchymal hepatic neoplasm.
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  • 81
    ISSN: 1432-1084
    Keywords: Key words: Kidney ; Ureteropelvic junction obstruction ; CT ; Trauma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to present CT findings of occult ureteropelvic junction obstruction in patients with renal trauma and to describe the clinical signs and singular CT features that are characteristically observed with trauma and are relevant to management of these patients. We retrospectively reviewed 82 helical CT studies in patients with renal trauma referred to our institution. We found 13 cases of occult preexisting renal pathology, six of which were occult ureteropelvic junction obstructions. The clinical presentation, radiologic findings of trauma according to the Federle classification, and CT findings of obstructed ureteropelvic junction are presented. We found three category-I lesions (one in a horseshoe kidney), two of them treated with nephrostomy because of increased ureteropelvic junction obstruction due to pelvic clots; two category-II lesions (parenchymal and renal pelvis lacerations) that had presented only with microhematuria; and one category-IV lesion (pelvic laceration alone). Pelvic extension was demonstrated in all the cases with perirenal collections. The CT studies in all the cases with suspected ureteropelvic junction obstruction showed decreased parenchymal thickness and enhancement, and dilatation of the renal pelvis and calyx, with a normal ureter. Computed tomography can provide information to confidently diagnose underlying ureteropelvic junction obstruction in renal trauma, categorize the traumatic injury (at times clinically silent) and facilitate proper management according to the singularities observed, such us rupture of the renal pelvis alone (Federle category IV) and increasing ureteropelvic obstruction due to clots which can be decompressed by nephrostomy.
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  • 82
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    European radiology 9 (1999), S. 841-852 
    ISSN: 1432-1084
    Keywords: Key words: Liver transplantation ; Hepatocellular carcinoma ; Cholangiocarcinoma ; MR Imaging ; CT ; Ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Hepatic transplantation has emerged as a potentially curative treatment of certain malignant hepatic neoplasms such as hepatocellular carcinoma, bile duct carcinoma, fibrolamellar hepatocellular carcinoma, metastases from neuroendocrine tumors, and epithelioid hemangioendothelioma. In the early years of hepatic transplantation, there was great enthusiasm to cure patients with unresectable hepatobiliary malignancy. This early enthusiasm was tempered by the unfavorable outcome of transplantation in advanced cases of malignancy and the organ-donor shortage. Presently, patients have to be selected with predictable likelihood for long-term survival. Pre-transplantation imaging is indispensable for detection, characterization, staging, and surgical road-mapping before the procedure. The present article focuses on the role of imaging modalities in these different aspects of preoperative assessment.
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  • 83
    ISSN: 1432-1084
    Keywords: Key words: Abdomen ; Neoplasms ; CT ; Lymphatic system ; Anatomy ; Metastases ; Omentum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to enhance our understanding of the pathways of lymphatic spread of primary carcinomas in the upper abdomen by recognizing the development, configuration, and frequency of nodal enlargement in discrete anatomic regions. The study included 417 patients with histologically confirmed carcinomas (CC) of the stomach (n = 267), liver (n = 98), gallbladder (n = 25), and bile ducts (n = 27). All patients were studied by high-resolution CT and tumor extension to the lymph nodes of the subperitoneal space was clearly identified in 59 patients [33 with CC of the stomach, 8 with CC of the gallbladder, 3 with CC of the bile ducts, and 15 with hepatocellular carcinoma (HCC)]. In 47 of 59 patients this extension was confirmed by surgery or aspiration biopsy. Three discrete anatomic groups of lymph nodes were recognized producing a relatively distinct CT configuration when involved: (a) the hepatoduodenal seen in 49 patients; (b) the peripancreatic demonstrated in 33 patients; and (c) the aortocaval recognized in 16 patients. These groups of lymph nodes can be seen individually involved or in combination. Recognition of involvement of these nodes is important for correct diagnosis and staging of upper abdominal malignancies. The development of this involvement follows the natural flow of lymph via the lesser omentum to the retroperitoneal space.
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  • 84
    ISSN: 1432-1084
    Keywords: Key words: Osteomyelitis ; Radiography ; Bone scintigraphy ; CT ; Ultrasound ; MR imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Conventional radiographs remain the initial imaging modality involved in the diagnosis of osteomyelitis. Bone scintigraphy and its specific agents did not only eliminate the problems of inherent low sensitivity of conventional radiographs, but also increased the specificity to higher degrees. Spiral CT, on the other hand, has solved several diagnostic problems, such as osteomyelitis of the sterno-clavicular junction and hidden areas in the pelvic bones. Magnetic resonance imaging with its multiplanar capability, greater anatomic details and excellent soft tissue bone marrow contrast resolution has a significant role in surgical planning and limb preservation. Ultrasound and US-guided aspiration has recently been involved in the diagnosis and management of osteomyelitis with several advantages particularly in children. Our goal in this review is to outline the ability of various imaging techniques by comparing their strengths and weaknesses in the diagnosis of osteomyelitis. Finally, we suggest various imaging algorithms for specific clinical scenarios. Spondylitis and septic arthritis are not discussed in this review.
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  • 85
    ISSN: 1432-1084
    Keywords: Key words: Vena cava ; Stenosis ; Obstruction ; Interventional procedure ; Neoplasm ; Grafts and prosthesis ; Thrombolysis ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this study was to report our experience on the management of superior vena cava obstruction (SVCO) secondary to malignant disease, using endovascular procedures. Twenty-six patients with SVCO due to primary or secondary tumors of the lung or the mediastinum, or catheter inserted for treatment of an extra-thoracic neoplasm, had an endovascular therapy which consisted of stenting, angioplasty, thrombo-aspiration or local fibrinolysis. Immediately after the procedure, rapid relief of symptoms occurred in 24 (90 %) of the patients. The mean Kishi's score decreased from 5.5 to 0.96. Immediate complications included one death related to pericarditis bleeding following fibrinolysis. Three patients relapsed after 20 days, 4 months and 6 months, and needed a second stenting. At 6 months the primary patency rate was 83 % and the secondary patency rate was 89 %. Endovascular treatment of SVCOs is a simple and safe procedure to restore the patency of the superior vena cava in malignant SVCO. It should be indicated in most cases as first-line treatment and performed as early as possible.
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  • 86
    ISSN: 1432-1084
    Keywords: Key words: Diaphragm ; Hepatic hernia ; Blunt trauma ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We report a case of blunt traumatic right diaphragm rupture with hepatic hernia. The diagnosis was first suggested by an abnormal hepatic location depicted on axial CT. This finding can be considered as a potentially new indirect sign of right diaphragm rupture in patients with blunt trauma. The diagnosis was then confirmed by reformatted CT and MR images.
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  • 87
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    European radiology 9 (1999), S. 1104-1106 
    ISSN: 1432-1084
    Keywords: Key words: Tendinitis ; CT ; Tendons ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Two cases of calcific tendinitis of gluteus maximus muscle are presented. The CT findings, including amorphous calcification without soft tissue mass and possible cortical erosion at the femoral enthesis of the gluteus maximus muscle, are highly suggestive of calcific tendinitis at this unusual but classical location. Ossifying entheses with well-defined cortical defect are frequent at the femoral insertion of the gluteus maximus muscle in asymptomatic subjects and must be differentiated from a real cortical erosion sometimes associated with these calcific tendinitis.
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  • 88
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    European radiology 9 (1999), S. 1117-1119 
    ISSN: 1432-1084
    Keywords: Key words: Tuberculosis ; Skeletal ; CT ; MR imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Chest wall involvement is an uncommon manifestation of musculoskeletal tuberculosis. We present computed tomography and magnetic resonance imaging findings in a case with multifocal musculoskeletal tuberculosis presenting as a breast mass. These radiological modalities are not diagnostic without histopathological confirmation, but they are valuable guides to surgery in defining the extent of disease involvement.
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  • 89
    ISSN: 1432-1084
    Keywords: Key words: Lipoid pneumonia ; Diagnosis ; Lung ; Disease ; CT ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The objective of this study was to describe high-resolution CT (HRCT) and MR findings of exogenous lipoid pneumonia and to correlate them with pathologic findings. A retrospective review of the medical records of our institution revealed seven patients with a diagnosis of lipoid pneumonia based on clinical data, chest films, bronchoalveolar lavage, and follow-up. Both HRCT and MR imaging were reviewed by two readers. Pathologic examination of the resected specimen or surgical biopsies were also reviewed in the four available cases. The HRCT findings were pulmonary consolidations (n = 6) with fatty (n = 3) or unspecific but low attenuation values (n = 3), areas of ground-glass opacities (n = 5), septal lines, and centrilobular interstitial thickening (n = 5). In five of the seven cases, a crazy-paving pattern of various spread was also present, either isolated (n = 1) or surrounding a pulmonary consolidation. In two cases traction bronchiectasis and cystic changes consistent with fibrosis were seen. At MR imaging (n = 2) a pulmonary consolidation of high signal intensity on T1-weighted image consistent with lipid content was present in one case. Pathologic examination (n = 4) showed the coexistence of lobules with lesions of various ages, sometimes in contiguous lobules, within the same patient. Recent lesions were those with alveolar fill-in by spumous macrophages and almost normal alveolar walls and septae. In more advanced lesions, lobules were filled in with larger vacuoles often surrounded by inflammatory infiltrates of alveolar walls, bronchiolar walls, and septa. The oldest lesions were characterized by fibrosis and parenchymal distortion around large lipid-containing vacuoles. The HRCT findings reflect pathologic findings in exogenous lipoid pneumonia. Although non-specific, consolidation areas of low attenuation values and crazy-paving pattern are frequently associated in exogenous lipoid pneumonia and are indicative of the diagnosis.
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  • 90
    ISSN: 1432-1084
    Keywords: Key words: Lung nodule ; CT ; Inflammatory pseudotumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Lung inflammatory myofibroblastic tumor is an uncommon cause of solitary lung nodule (0.7 % of lung tumors). The principal site of inflammatory pseudotumor is the lung, but it can also occur elsewhere in various organs. Although benign, they may be locally very aggressive. Recurrent and multifocal forms have been described. Since they are likely to mimic malignant neoplasms, accurate histopathologic diagnosis is necessary in order to guide appropriate surgical excision and avoid aggressive treatments. We report a case of lung involvement in a young adult with radiologic and pathologic correlations.
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  • 91
    ISSN: 1432-1084
    Keywords: Key words: Castleman disease ; CT ; MR imaging ; Paraneoplastic pemphigus ; Abdomen ; Neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We describe the CT and MRI features of a case of Castleman disease which was unusual by both its retroperitoneal location and its association with paraneoplastic pemphigus.
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  • 92
    ISSN: 1432-1084
    Keywords: Key words: Lung neoplasms ; Staging ; Pleura ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of this investigation was to evaluate whether thin-sectional CT with different reconstruction algorithms can improve the diagnostic accuracy with regard to chest wall invasion in patients with peripheral bronchogenic carcinoma. Forty-one patients with intrapulmonary lesions and tumor contact to the thoracic wall as seen on CT staging underwent additional 1-mm CT slices with reconstruction in a high-resolution (HR) and an edge blurring, soft detail (SD) algorithm. Five criteria were applied and validated by histological findings. Using the criteria of the intact fat layer, HRCT had a sensitivity of 81 % and a specificity of 79 %, SD CT had a sensitivity of 96 % and a specificity of 78 %, and standard CT technique had a sensitivity of 50 % and a specificity of 71 %, respectively. Regarding changes of intercostal soft tissue, HRCT achieved a sensitivity of 71 % and a specificity of 96 %, SD CT had a sensitivity of 94 % and a specificity of 96 % (standard CT technique: sensitivity 50 % and specificity 96 %) . For the other criteria, such as pleural contact area, angle, and osseous destruction, no significant differences were found. Diagnostic accuracy of chest wall infiltration can be improved by using thin sectional CT. Especially the application of an edge-blurring (SD) algorithm increases sensitivity and specificity without additional costs.
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  • 93
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    European radiology 9 (1999), S. 1321-1323 
    ISSN: 1432-1084
    Keywords: Key words: Hydatid disease ; Chest ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The greatest difficulty in the CT diagnosis of perforated pulmonary hydatid cyst (PPHC) is the increase in the attenuation numbers following infection. Because of the solid density of infected hydatid cysts, the differentiation from an abscess or neoplasm is usually impossible. The aim of this study was to evaluate the value of “air bubble” as a new CT sign in the diagnosis of PPHC. Sixty-five patients (28 men and 37 women) with PPHC were included in the study. As a control group, 55 patients who had malignant (n = 36) or non-malignant (n = 19) pulmonary diseases were also examined. Radiological diagnosis with classical CT findings was made in only 38 of 65 patients (58.5 %) with PPHC. Air bubble sign was positive in 54 of the patients with PPHC (sensitivity 83.1 %) but only 3 of 55 patients in control group (specificity 94.5 %). When we analyzed the CT scans with classical CT findings including air bubble, the diagnosis of PPHC was made in 61 of patients (93.8 %). It is concluded that “air bubble sign” is a valuable CT finding in the diagnosis of PPHC.
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  • 94
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    European radiology 9 (1999), S. 1335-1338 
    ISSN: 1432-1084
    Keywords: Key words: Sclerosing stromal tumor ; MR imaging ; CT ; Dynamic study ; Ovarian tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Sclerosing stromal tumor is a rare ovarian neoplasm. We describe the radiologic findings of sclerosing stromal tumor in two patients. In both patients, MR and CT images showed a large mass in the left adnexal region. On dynamic contrast-enhanced images, the tumors showed early peripheral enhancement with centripetal progression.
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  • 95
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    European radiology 9 (1999), S. 1366-1375 
    ISSN: 1432-1084
    Keywords: Key words: Myelofibrosis ; Plain film ; Ultrasound ; CT ; MR imaging ; Extramedullary hematopoiesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this review is to illustrate the wide range of radiological abnormalities in myelofibrosis. Myelofibrosis, also called myeloid metaplasia, is a myeloproliferative disorder of unknown etiology. The common imaging findings in patients with myelofibrosis are osteosclerosis, hepatosplenomegaly, and lymphadenopathies. In addition, extramedullary hematopoiesis may develop in multiple sites such as chest, abdomen, pelvis, and central nervous system, simulating malignant disease. Selected plain-film, CT, and MR images in patients with myelofibrosis are shown as pictorial essay to allow ready recognition of the most common imaging abnormalities of the disease.
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  • 96
    ISSN: 1432-1084
    Keywords: Key words: Blood diseases ; CT ; Extramedullary haematopoiesis ; Presacral mass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. We present the case of a 60-year-old woman with no known blood disease who developed an extramedullary haematopoiesis of presacral localization that affected the right sciatic nerve. The diagnosis was made with imaging studies and CT-guided fine-needle aspiration.
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  • 97
    ISSN: 1432-1084
    Keywords: Key words: Esophageal varices ; CT ; Endoscopic variceal ligation ; MPR ; 3D image
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this study was to demonstrate the utility of helical CT in assessing the therapeutic effects of endoscopic variceal ligation (EVL). Twenty-four patients with esophageal varices were examined. Helical scanning was initiated 60 s after intravenous injection (Iopamidol 300 mgI/ml, total 120 ml, 3 ml/s) was started. Esophageal varices were clearly depicted as high-density areas. Multiplanar reformation and 3D images demonstrated collateral circulation three-dimensionally. After EVL, mucosal high-density areas had diminished markedly, but collateral veins around the esophagus, and gastro- and/or spleno-renal shunts, were unchanged in all patients. Of 21 patients with collateral circulation, esophageal varices recurred endoscopically in 6 patients within 12 months. In 3 patients without collateral circulation, esophageal varices did not recur within 12 months. From these findings, we conclude that helical CT is a useful method for assessing the therapeutic effects of EVL.
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  • 98
    ISSN: 1432-1084
    Keywords: Key words: Coronary vessels ; anomalies ; Coronary vessels ; CT ; Coronary vessels ; MR studies ; Coronary angiography ; Electron-beam CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. An anomalous origin of the left coronary artery arising from the pulmonary artery is a congenital malformation rarely described in adults. We report the case of a 65-year-old patient with this anomaly. Clinical presentation, imaging identification (coronary angiogram, MRI and electron-beam CT), surgical treatment and angiographic long-term follow-up are described.
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  • 99
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    European radiology 9 (1999), S. 1590-1592 
    ISSN: 1432-1084
    Keywords: Key words: Kidney ; Kidney neoplasms ; CT ; Fat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The differential diagnosis of renal masses containing fatty foci is limited to a small number of well-defined tumors, angiomyolipoma being the most frequent. In recent years clear cell carcinomas with intratumoral fatty foci have been reported, due to either entrapment of local fat or to regressive adipose metaplasia. Demonstration of focal calcifications is a valuable sign, being relatively common in carcinomas while rare in more benign lesions. We report a case of a foreign-body granuloma of the kidney, containing both calcifications and foci of fat. The value of this case, in our opinion, is that it demonstrates that detection of the previously mentioned features in a renal mass does not necessarily imply a presumptive diagnosis of renal cell carcinoma.
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  • 100
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    European radiology 9 (1999), S. 1596-1598 
    ISSN: 1432-1084
    Keywords: Key words: Penile metastasis ; Corpus cavernosum ; Bladder cancer ; CT ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Metastases of the penis are uncommon, with only approximately 300 cases reported since 1870. In up to 70 % of patients, the primary tumour is located in the urogenital tract. Furthermore, isolated metastases of the penis are exceptionally rare. We report a case of solitary squamous cell metastasis of the penis presenting with painful swelling initially thought to be inflammatory in origin. The CT and MR imaging findings are presented with a short review of the literature.
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