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61.
KE Veldkamp KP Van Kessel J Verhoef JA Van Strijp 《Canadian Metallurgical Quarterly》1997,21(5):541-551
c-fos induction was investigated as a potential component in the avian photic entrainment pathway and as a possible means of locating the central pacemaker in birds. In both quail (Coturnix coturnix japonica) and starlings (Sturnus vulgaris) exposure to 1 h of light induced Fos-lir in the visual suprachiasmatic nucleus but not in the medial suprachiasmatic nucleus. However, the degree of c-fos induction in the visual suprachiasmatic nucleus was similar at different circadian times despite the fact that the light pulses caused differential phase shifts in the locomotor rhythm. For golden hamsters the same experiment resulted in significantly different levels of Fos-lir in the suprachiasmatic nucleus, as well as different phase shifts. Starlings and hamsters were also entrained to T-cycles that caused a large daily phase shift (T = 21.5 h in starlings, T = 22.67 hours in hamsters), or no daily phase shift (T = free running period). No difference in the induced levels of Fos-lir in the visual suprachiasmatic nucleus region was observed between the two groups of starlings, but in hamsters there were significantly different levels of Fos-lir in the suprachiasmatic nucleus between the two groups. 相似文献
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64.
KP Trevett 《Canadian Metallurgical Quarterly》1998,280(10):883-884
65.
KP Rao 《Canadian Metallurgical Quarterly》1995,7(7):623-645
In this review, an attempt was made to summarize some of the recent developments in the application of collagen as a biomaterial and in drug delivery systems. The main applications covered include: collagen for burn/wound cover dressings; osteogenic and bone filling materials; antithrombogenic surfaces; and immobilization of therapeutic enzymes. Recently, collagen used as a carrier for drug delivery has attracted many researchers throughout the world. The use of collagen for various drug delivery systems has also been reviewed in this article. Collagen-based drug delivery systems include: injectable microspheres based on gelatin (degraded form of collagen); implantable collagen-synthetic polymer hydrogels; interpenetrating networks of collagen; and synthetic polymers collagen membranes for ophthalmic delivery. Recent efforts to use collagen-liposomal composites for controlled drug delivery, as well as collagen as controlling membranes for transdermal delivery, were also reviewed. In this review, the main emphasis was on the work done in our laboratory. 相似文献
66.
MC Blans JM Conemans JK van der Veer KP Bouter 《Canadian Metallurgical Quarterly》1998,142(39):2154-2156
A 32-year-old woman was admitted with signs of recurrent hypoglycaemia. Within 72 hours hypoglycaemia was successfully provoked by prolonged fasting. Also, blood samples demonstrated high levels of serum insulin and C-peptide and the insulin-glucose ratio was abnormally high. An insulinoma was strongly suspected. However, extensive imaging displayed no tumour in the pancreas. The patient also had extensive psychological and social problems. The psychiatrist suggested a factitious disorder. High serum concentrations of insulin and C-peptide in combination with the psychiatric disorder led to the suspicion of abuse of sulfonylurea derivatives by the patient. This was confirmed by toxicological screening. A patient with unexplained hypoglycaemia, especially if an insulinoma cannot be detected, should be suspected of abusing sulfonylurea derivatives. 相似文献
67.
The toxicity on three human tumor cell lines (A431, HeLa and MCF7) of five phenanthroperylenequinones (hypericin and derivatives) and two perylenequinones (cercosporin and calphostin C) was investigated after photosensitization (4 J/cm2). Furthermore, the antiproliferative effect on HeLa cells was studied for the phenanthroperylenequinones. Hypericin, 2,5-dibromohypericin, 2,5,9,12-tetrabromohypericin and perylenequinones displayed a potent cytotoxic and antiproliferative effect in the nanomolar range. Hypericin dicarboxylic acid exhibited no photoactivity. In general, the antiproliferative activity correlated well with the photocytotoxicity. However, the nonphotocytotoxic compound hexamethylhypericin showed potent antiproliferative activity in the nanomolar range, probably exerting its action by protein kinase C inhibition. Without light irradiation, no cytotoxic and antiproliferative effect was observed for any photocytotoxic phenanthroperylenequinone compound. Furthermore, confocal laser microscopy revealed that the subcellular localization in A431 cells was similar for the photoactive compounds; the photosensitizers were mainly concentrated in the perinuclear region, probably corresponding with the Golgi apparatus and the endoplasmic reticulum. In addition, the accumulation of the photosensitizers in HeLa cells was investigated. All compounds except hypericin dicarboxylic acid were found to concentrate to a large extent in the cells. The compound 2,5,9,12-tetrabromohypericin seemed intrinsically more effective than hypericin since the intracellular concentration of the bromoderivative was a magnitude of order lower than that of hypericin although both compounds showed similar photobiological activity. 相似文献
68.
OBJECTIVE: To determine the variation in the estimated maternal cerebral perfusion and cerebrovascular resistance (the resistance area product) in the puerperium. METHODS: The maternal middle cerebral artery was evaluated by transcranial Doppler ultrasound in ten women 2 days before labor, in 21 women in early labor and at 24 and 48 hours postpartum, and in 6 women at 1 week postpartum. Cerebral blood flow velocities were determined. Women were diagnosed initially with mild preeclampsia. Estimated cerebral perfusion pressure was Vmean/[Vmean - Vdiastolic] [BPmean - BPdiastolic]. Because the diameter of the vessels could not be measured directly, an index of resistance was calculated: the resistance area product = BPmean/velocitymean. We calculated an index of cerebral blood flow to be estimated cerebral perfusion pressure divided by resistance area product. Our study had a power of 80% to detect a 16-cm/second increase in middle cerebral blood flow velocity. RESULTS: Estimated maternal cerebral perfusion was maintained for up to 1 week postpartum. Cerebrovascular resistance did not change in the puerperium. Cerebral blood flow index (+/-standard deviation) was significantly increased at 1 week postpartum compared with early labor levels (28.3 +/-6.9 versus 46.7+/-15.6, respectively) (P < .05). CONCLUSION: Cerebral blood flow 1 week postpartum increased significantly over early labor values. These persistent changes in the cerebral vasculature might put patients at risk for seizures up to 1 week postpartum. 相似文献
69.
During T cell development, assembly of the mutisubunit T cell receptor (TCR) complex is regulated by the differential stability of newly synthesized TCRalpha molecules, having a half-life of approximately 20 min in immature CD4+CD8+ thymocytes compared with >75 min in mature T cells. The molecular basis for TCRalpha instability in CD4+CD8+ thymocytes is unknown but has been postulated to involve abnormalities in N-glycan processing and calnexin assembly as perturbation of these pathways markedly destabilizes TCRalpha proteins in all other T cell types examined. Here, we compared the processing of TCRalpha glycoproteins and their assembly with calnexin and calreticulin chaperones in CD4+CD8+ thymocytes and splenic T cells. These studies show that TCRalpha glycoproteins synthesized in CD4+CD8+ thymocytes were processed in a similar manner as those made in splenic T cells and that TCRalpha proteins stably associated with calnexin in both cell types. Interestingly, however, TCRalpha association with the calnexin-related molecule calreticulin was decreased in CD4+CD8+ thymocytes compared with splenic T cells. Finally, TCRalpha degradation in CD4+CD8+ thymocytes was impaired by inhibitors of proteasome activity, which was correlated with stabilization of calnexin.TCRalpha complexes. These data demonstrate that calnexin association is not sufficient to protect TCRalpha proteins from rapid degradation in CD4+CD8+ thymocytes, suggesting that additional components of the quality control system of the endoplasmic reticulum operate to ensure the proper folding of nascent TCRalpha glycoproteins. 相似文献
70.
To estimate ethanol consumption by university students attending a student health facility, a biochemical marker of alcohol intake [whole blood associated acetaldehyde (WBAA)] was quantified by fluorimetric HPLC. Over a two year period we studied blood samples, coded by date and sex, from 645 females and 332 males, and compared the results to previously established reference ranges for teetotalers by sex. Men had higher absolute values for WBAA than women (9.9 versus 9.5 microM in the present study). However, significantly greater numbers of women (74%) than men (44%) had WBAA levels above the 99th percentile for teetotalers. Variations occurred during the academic year, with significant elevations occurring in the late fall and winter months. Testing of WBAA levels in a student health service may be important especially for women to facilitate counseling on the dangers of alcohol abuse. 相似文献