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  • 1
    ISSN: 1365-2826
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Ghrelin, a novel growth hormone (GH)-releasing peptide, was isolated from the rat stomach as an endogenous ligand to the growth hormone secretagogues receptor. It is known that ghrelin stimulates the release of GH from the rat anterior pituitary gland, but the intracellular signal cascade in somatotrophs has not yet been clarified. In this study, using an isolated cell perifusion system, we examined whether ghrelin- and growth hormone-releasing hormone (GHRH)-induced GH secretion from rat pituitary cells depends on intra- and extracellular Ca2+ and voltage-gated Ca2+ channels. For this purpose, we first measured ghrelin- or GHRH-stimulated GH concentration following treatment with reduced extracellular Ca2+ and/or thapsigargin, an endoplasmic reticulum Ca2+ ATPase inhibitor. Reductions in the extracellular Ca2+ concentration to 0.25 mM and to 0 mM resulted in decreases in ghrelin-stimulated GH secretion to 81% and 39% and decreases in GHRH-induced GH secretion to 83% and 13%, respectively, compared to the levels in the case of 2.5 mM Ca2+ concentration, suggesting that extracellular Ca2+ is essential for both ghrelin- and GHRH-induced GH secretion. Pretreatment with thapsigargin resulted in a reduction in ghrelin-induced GH secretion to approximately 60% of the control level, but GHRH treatment had not effect on the GH secretion. Moreover, preincubation with thapsigargin and 0 mM extracellular Ca2+ concentration resulted in significant inhibition of GHRH- and ghrelin-induced GH secretion. Subsequently, to determine whether ghrelin-stimulated GH secretion was induced through voltage-gated Ca2+ channels, we measured the ghrelin-stimulated GH concentration following treatment with nifedipine, an L-type Ca2+ channel inhibitor, and found that the amount of GH secretion was reduced to 44% of the control level. Furthermore, by replacement of extracellular Na2+ in the medium with N-methyl-d(–)-glucamine, an impermeable molecule, GH secretion was reduced to 47%. In this study, we demonstrated that the GH-stimulatory effect of ghrelin, unlike that of GHRH, is achieved through both intracellular and extracellular Ca2+ sources and that ghrelin-induced extracellular Ca2+ influx involves an L-type voltage-gated Ca2+ channel and Na+ influx.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science, Ltd
    Journal of neuroendocrinology 14 (2002), S. 0 
    ISSN: 1365-2826
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Ghrelin, a novel growth hormone (GH)-releasing peptide, was recently isolated from the rat stomach as an endogenous ligand to growth hormone secretagogue receptor (GHS-R). Ghrelin specifically stimulates the release of GH from the rat anterior pituitary gland, but the regulational effect of ghrelin on GH secretion has not yet been clarified. We used a perifusion system to examine the single effect and combined effects of ghrelin with growth hormone-releasing hormone (GHRH) and somatostatin on GH secretion from rat anterior pituitary cells. The increase in GH concentration due to ghrelin stimulation showed a transitory peak that was almost the same as that previously reported for GHS, but apparently distinct from that of GHRH. Ghrelin (10−10 M to 10−8 M) stimulated GH secretion from the rat anterior pituitary cells in a dose-dependent manner. Serial ghrelin stimulation of the dispersed cells at 1-h intervals decreased the GH response, but the response recovered with stimulation at 3-h intervals, indicating that ghrelin strongly desensitized cells. Costimulation with ghrelin and GHRH elicited neither a synergistic nor an additive GH response from the rat pituitary cells. Furthermore, pretreatment to anterior pituitary cells with somatostatin strongly abolished ghrelin- and/or GHRH-stimulated GH secretion. In this study, we demonstrated that ghrelin caused weaker GH secretion than that caused by GHRH, and we also showed that costimulation with GHRH had no additive or synergistic effect on GH secretion, suggesting that ghrelin indirectly affects coordinated GH release from pituitary gland, as found in vivo.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: MyD88 is a key adaptor molecule for signalling via Toll-like receptors (TLRs) and the response to gut commensal microbes. To investigate the role of TLRs/MyD88 pathway in the development of the gut-associated lymphoid tissue (GALT), we examined the development of Peyer's patches (PPs) and cryptopatch (CP), and also one of effector compartment, intraepithelial lymphocyte (IEL) in MyD88–/–, TLR2–/– and TLR4–/– mice. In MyD88–/– mice, the organogenesis of PPs was not disturbed. However, PPs in 2-week-old MyD88–/– mice were significantly smaller than those in MyD88+/– mice. Also, in 2-week-old TLR4–/–, but not TLR2–/– mice, PPs did not develop rapidly. The development of PPs in MyD88–/– and TLR4–/– mice was completely recovered in 10 weeks. PP cells from MyD88–/– mice showed significant decrease in proliferation when stimulated with lipopolysaccharide. The development of CP and IEL was also normal in 10-week-old MyD88–/– mice. These results suggest that the TLRs/MyD88 pathway might be involved in the development of PPs only at early postnatal stage, and TLRs/MyD88-independent signalling is critically involved in the development of GALT in adult mice.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Lympho-haemopoietic progenitors residing in murine gut cryptopatches (CPs) have been shown to generate intestinal extrathymic intraepithelial lymphocytes (IELs). However, the role of CPs in the development of intestinal inflammation remains unclear. To investigate the role of CPs in the development of intestinal inflammation, we examined SAMP1/Yit mice, which spontaneously develop a chronic intestinal inflammation localized to the terminal ileum and cecum. Here, we showed the sharp correlation between the disease onset and the decreased number of CPs, resulting in decreased number of both thymus-independent IELs including T-cell receptor γδ+ (TCRγδ+) and CD8αα+TCRαβ+ cells but not thymus-dependent CD8αβ+TCRαβ+ and CD4+TCRαβ+ cells in SAMP1/Yit mice. These data provide the first suggestion that thymus-independent IELs derived from CP might play protective role against the onset and the development of intestinal inflammation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 58 (2003), S. 0 
    ISSN: 1365-2044
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1437-7772
    Schlagwort(e): Key words Rectal cancer ; Poorly differentiated adenocarcinoma ; Multidisciplinary treatment ; Radiotherapy ; Tegafur suppository ; OK-432
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We administered multidisciplinary treatment to a 37-year-old man with poorly differentiated adenocarcinoma of the rectum which exhibited a fistula between the rectum and the urinary bladder; the tumor was considered unresectable because of extensive local spread at initial evaluation, including a laparotomy. The patient received radiotherapy, consisting of a total dose of 50 Gy, given as fractions of 2 Gy per day 4 days a week. Concurrently with the radiation, the patient also received twice daily a tegafur [1-(2-tetrahydrofuryl)-5-fluorouracil] suppository (750 mg) and 5-fluorouracil ointment (2.5 g) applied to the perianal involved skin lesion. In addition, 5 KE of OK-432 was injected into the tumor nine times during the course of radiation. Because the tumor responded well to this radio-chemo-immunotherapy, the patient was discharged, and was treated only with tegafur suppositories for almost 3 years on an outpatient basis (total dose of tegafur, approximately 1500 g). As a result of the combined therapy, the tumor completely disappeared, while only the recto-urinary fistula remained. The patient has survived without recurrence for 50 months after his initial presentation, and his levels of carcinoembryonic antigen and immunosuppressive acidic protein have decreased from pretreatment values of 85 ng/ml and 1220 μg/ml, respectively, to 0.8 ng/ml and 459 μg/ml, respectively. Although this is only one case, it shows that appropriate multidisciplinary treatment may achieve excellent results even in patients with unresectable poorly differentiated adenocarcinomas of the rectum.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 1432-0533
    Schlagwort(e): Key words Astrocytic plaque ; Dementia ; Guam ; Parkinsonism ; Tufted astrocyte
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A 58-year-old Chamorro female patient, who died in 1993, was examined clinicopathologically. At the age of 51, she suffered from hemiparkinsonism, then bradykinesia, rigidity without tremor, and dementia. Extrapyramidal symptoms developed, and at the age of 57, vertical gaze palsy was noted. The clinical diagnosis was parkinsonism-dementia complex (PDC) with vertical gaze palsy. The brain showed atrophy in the frontal and temporal lobes, and the atrophy was accentuated in the dentate gyrus, Ammon’s horn and parahippocampal gyrus. The basal ganglia, thalamus and midbrain were moderately atrophic. The substantia nigra and locus ceruleus were completely depigmented. Numerous neurofibrillary tangles (NFTs) were seen in the subiculum and amygdaloid nucleus. Many NFTs were evident in the parahippocampal gyrus, lateral occipitotemporal gyrus, insula, Sommer sector, basal nucleus of Meynert, lateral nucleus of the thalamus, subthalamic nucleus and brain stem, and several were observed in the globus pallidus and hypothalamus. The Sommer sector, substantia nigra, locus ceruleus and basal nucleus of Meynert showed severe loss of neurons, and a moderate loss of neurons was exhibited by the globus pallidus. These findings were apparently consistent with those associated with PDC. However, in this patient, severe neuronal loss was seen in the subthalamic nucleus and lateral nucleus of the thalamus, and grumose degeneration, which has not previously been reported in PDC, was seen in the dentate nucleus. In addition, many tufted astrocytes, which have been reported to occur in progressive supranuclear palsy (PSP) and postencephalitic parkinsonism, but scarcely observed in PDC, were present. Furthermore, astrocytic plaques, which have been considered as a specific finding of corticobasal degeneration (CBD), were observed in the cerebral cortex. On the other hand, granular hazy astrocytic inclusions, previously reported to occur in PDC, were not seen. Chromatolytic neurons were not observed. The question thus arises as to whether it is appropriate to consider this patient as having suffered from a combination of PDC, PSP and CBD. From the view points of absence of granular hazy astrocytic inclusions and chromatolytic neurons, and of tufted astrocytes in the neostriatum, it is conceivable that this patient is a case of a new disease entity.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 1432-0533
    Schlagwort(e): Key words Alzheimer’s disease ; Corticobasal ¶degeneration ; Paired helical filaments ; Thiazin red ; Tau
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Thiazin red (TR), a fluorochrome that has an affinity to fibrillary structures such as neurofibrillary tangles (NFTs) or senile plaques, was utilized to investigate assembly of tau protein into fibrils in tau-immunopositive neocortical neurons of corticobasal degeneration (CBD) and of Alzheimer’s disease (AD). Double fluorescence with anti-paired helical filament monoclonal antibody (AT8) and TR was followed by either the Gallyas or Bodian silver impregnation method, which enabled a comparison of the staining features by three different methods on the same neuron. NFTs of AD were uniformly stained by TR and Gallyas method. Most of tau-immunopositive neurons of CBD were similarly stained by Gallyas method but barely or only weakly by TR or Bodian method, suggesting that tau in neocortical neurons of CBD is less liable to form fibrillary structures than in those of AD, easily distinguishable by TR staining. Clarifying the process of tau assembly using this fluorochrome will give a clue to understanding mechanisms of tau deposition, which may be different in various neurological disorders.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 256 (1978), S. 617-618 
    ISSN: 1435-1536
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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