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751.
BS Hahn K Baek WS Kim CS Lee IL Chang YS Kim 《Canadian Metallurgical Quarterly》1998,36(12):1887-1893
The gene of capillary permeability-increasing enzyme-2 (CPI enzyme-2) was cloned from the cDNA library of Agkistrodon caliginosus and its nucleotide sequence was determined. Its sequence indicates that CPI enzyme-2 is synthesized as a pre-zymogen of 258 amino acid residues, including a putative secretory signal peptide of 18 amino acids and a proposed zymogen peptide of 6 amino acids. The amino terminal sequence deduced from the cDNA sequence was exactly consistent with that of CPI enzyme-2 except for the substitution of an amino acid (Gly27-->Ser). The open reading frame is very similar to those of plasminogen activator and thrombin-like proteases cloned from other snakes. The clone encoding CPI enzyme-2 belongs to the serine protease family. The active site of the enzyme is highly conserved at His41, Asp86 and Ser180. Its possible glycosylation sites, Asn-X-Thr/Ser, are located at amino acid residues 20-22, 55-57, 79-81 and 97-99. 相似文献
752.
TR Cummins J Zhou FJ Sigworth C Ukomadu M Stephan LJ Ptácek WS Agnew 《Canadian Metallurgical Quarterly》1993,10(4):667-678
Hyperkalemic periodic paralysis (HYPP), one of several inheritable myotonic diseases, results from genetic defects in the human skeletal muscle Na+ channel. In some pedigrees, HYPP is correlated with a single base pair substitution resulting in a Met replacing Thr704 in the fifth transmembrane segment of the second domain. This region is totally conserved between the human and rat channels. We have introduced the human mutation into the corresponding region of the rat muscle Na+ channel cDNA and expressed it in human embryonic kidney 293 cells. Patch-clamp recordings show that this mutation shifts the voltage dependence of activation by 10-15 mV in the negative direction. The shift results in a persistent Na+ current that activates near -70 mV; this phenomenon could underlie the abnormal muscle activity observed in patients with HYPP. 相似文献
753.
754.
BACKGROUND: Although endoscopic evaluation of the gastrointestinal tract is commonly performed to evaluate iron deficiency, little data is available regarding the underlying causes, yield of evaluation, and long-term outcome for those in whom gastrointestinal and systemic symptoms and signs are absent. METHODS: In- or out-patients seen by the gastroenterology consultative service at a large inner-city hospital over a 56-month period were considered eligible for the study when iron deficiency (serum ferritin <50 ng/mL) was documented. Exclusion criteria included: any gastrointestinal or systemic symptoms/signs, radiographic or endoscopic examinations of the gastrointestinal tract within 3 and 5 years, respectively, or obvious source of blood loss. Patients underwent colonoscopy and if no lesions other than carcinoma were found, upper endoscopy was then performed with a pediatric colonoscope. RESULTS: Fifty-two patients were evaluated (mean age, 66 +/- 13 years; range, 20 to 89 years; 32 men/20 women). At the time of evaluation, the mean (+/-SD) hematocrit was 25% +/- 7% (range, 14% to 42%). Overall, 23 patients (44%; 95% CI 30% to 59%) had an identifiable gastrointestinal lesion considered the cause of iron deficiency, including: colonic carcinoma, 11 (21%); colonic and/or esophagogastric/duodenal vascular ectasias, 9 (17%); and gastric carcinoma, colonic polyposis, and colonic ulcers in 1 patient each. Long-term follow-up (median 24 months, range 2 to 63 months) identified only 1 patient with a cause found (colonic carcinoma), and in this patient, complete colonoscopy was not technically possible at the time of initial evaluation. There were no clinical or laboratory features that distinguished patients with an etiology for iron deficiency to the idiopathic group. CONCLUSIONS: Approximately half of patients with iron deficiency in whom gastrointestinal or systemic signs or symptoms are absent have an underlying gastrointestinal lesion. Nevertheless, despite a thorough endoscopic evaluation, some patients will have no etiology found; the prognosis for these patients is excellent. 相似文献
755.
CJ Ying WS Yan MY Zhao XL Ye H Xie SY Yin XS Zhu 《Canadian Metallurgical Quarterly》1997,10(4):451-455
The developing heart primordium strongly expresses N-cadherin. In order to investigate the role of this adhesion molecule in heart morphogenesis, chicken embryos were cultured at stages 5-12, and injected with anti-N-cadherin antibodies that can specifically block the activity of this cadherin. In the injected embryos, the epimyocardial layers, which develop bilaterally from the splanchnic mesoderm, did not fuse to form a single cardiac tube. Moreover, each of the unfused layers became fragmented into epithelioid clusters. At the cellular level, large intercellular gaps were observed in the antibody-treated myocardial layers. These disorganized myocardial layers beat to some extent, suggesting that their differentiation was not blocked; however, their contraction was not coordinated. Morphogenesis of other tissues, not only N-cadherin-negative but also N-cadherin-positive tissues, such as the neural tube and notochord, proceeded normally even in the presence of anti-N-cadherin antibodies. These results suggest that N-cadherin is indispensable for heart formation, but not for morphogenesis of the other tissues, at the developmental stages examined. For the latter processes, expression of other cadherin subtypes presumably compensated for the loss of N-cadherin activity. 相似文献
756.
WJ Qui?ones-Baldrich SM Nene HA Gelabert WS Moore 《Canadian Metallurgical Quarterly》1997,11(4):331-341
This study examines the contribution of GABAergic inhibition to the discharge pattern and recovery properties of 110 bat inferior collicular neurons by means of bicuculline application to their recording sites. When stimulated with single pulses, 74 (67%) neurons discharged one or two impulses (phasic responders), 19 (17%) discharged three to ten impulses (phasic bursters) and 17 (16%) discharged impulses throughout the entire stimulus duration (tonic responders). Bicuculline application changed phasic responders into phasic bursters or tonic responders, increased the number of impulses by 10-2000% and shortened the response latency of most neurons. When stimulated with pairs of sound pulses, the recovery cycles of these neurons can be described as: (1) long inhibition (n = 49, 45%); (2) short inhibition (n = 41, 37%); and (3) fast recovery (n = 20, 18%) based upon the 50% recovery time that was either longer than 20 ms, between 10 and 20 ms or shorter than 10 ms. Bicuculline application shortened the 50% recovery time of most neurons by 11-2350% allowing them to respond to pairs of sound pulses at very short interpulse intervals. These data demonstrate that GABAergic inhibition contributes significantly to auditory temporal processing. 相似文献
757.
TN Jacobsen BJ Morgan U Scherrer SF Vissing RA Lange N Johnson WS Ring PS Rahko P Hanson RG Victor 《Canadian Metallurgical Quarterly》1993,73(2):367-378
The aim of this study was to reexamine the hypothesis that cardiopulmonary baroreflexes are more important than sinoaortic baroreflexes in causing vasoconstriction in the skeletal muscle circulation during orthostatic stress. We recorded muscle sympathetic nerve activity (MSNA) with microelectrodes in the peroneal nerve (and forearm blood flow with venous occlusion plethysmography) in normal subjects (innervated ventricles) and in heart transplant recipients (denervated ventricles) during graded lower body negative pressure (LBNP) performed alone and in combination with intravenous infusion of phenylephrine, which was titrated to eliminate the orthostatically induced fall in blood pressure and thus the unloading of both carotid and aortic baroreceptors. The principal new findings are as follows: (1) The increases in both MSNA and forearm vascular resistance during multiple levels of LBNP were not attenuated by heart transplantation, which causes ventricular but not sinoaortic deafferentation. (2) In heart transplant recipients, a small increase in MSNA during mild LBNP was dependent on a decrease in arterial pressure, but in normal subjects, a similar increase in MSNA occurred in the absence of any detectable decrease in the aortic pressure stimulus to the sinoaortic baroreceptors. (3) In normal subjects, the large increase in MSNA during a high level of LBNP was dependent on a decrease in arterial pressure and could be dissociated from the decrease in central venous pressure. Taken together, the findings strongly suggest that sinoaortic baroreflexes are much more important and ventricular baroreflexes are much less important than previously thought in causing reflex sympathetic activation and vasoconstriction in the human skeletal muscle circulation during orthostatic stress. 相似文献
758.
CC Chao S Hu KB Shark WS Sheng G Gekker PK Peterson 《Canadian Metallurgical Quarterly》1997,281(2):998-1004
Opiates modulate many macrophage functions. Microglia, the resident macrophages of the brain, migrate to sites of inflammation within the CNS. Using primer sets designed to span the entire open reading frame of the human brain mu opioid receptor (MOR), we found that microglial cells constitutively expressed MOR mRNA. The cDNA sequences of the MOR open reading frame in microglia were identical to those of human brain tissue. Using enriched human fetal microglial cell cultures, we found that morphine potently inhibited the directed migration (chemotaxis) of microglial cells toward C5a in a dose-dependent manner with an IC50 value of 1 fM morphine. We also found that DAMGO, a selective MOR ligand, dose-dependently suppressed microglial cell chemotaxis with an IC50 value of 1 nM, which was significantly attenuated by 10 nM beta-funaltrexamine. Taken together, these findings suggest that activation of constitutively expressed MOR inhibits microglial cell chemotaxis and support the notion of an anti-inflammatory role of MOR within the brain. 相似文献
759.
M Bender FB Imam WS Talbot B Ganetzky DS Hogness 《Canadian Metallurgical Quarterly》1997,91(6):777-788
The steroid hormone ecdysone directs Drosophila metamorphosis via three heterodimeric receptors that differ according to which of three ecdysone receptor isoforms encoded by the EcR gene (EcR-A, EcR-B1, or EcR-B2) is activated by the orphan nuclear receptor USP. We have identified and molecularly mapped two classes of EcR mutations: those specific to EcR-B1 that uncouple metamorphosis, and embryonic-lethal mutations that map to common sequences encoding the DNA- and ligand-binding domains. In the larval salivary gland, loss of EcR-B1 results in loss of activation of ecdysone-induced genes. Comparable transgenic expression of EcR-B1, EcR-B2, and EcR-A in these mutant glands results, respectively, in full, partial, and no repair of that loss. 相似文献
760.
GA Papanicolaou BR Meyers WS Fuchs SL Guillory MH Mendelson P Sheiner S Emre C Miller 《Canadian Metallurgical Quarterly》1997,24(6):1172-1177
We report the frequency and type of infectious ocular complications following orthotopic liver transplantation (OLT) and review diagnostic and therapeutic strategies. During the period September 1988 through November 1994, 684 patients underwent OLT at Mount Sinai Hospital (New York). Nine orthotopic liver transplant patients (1.3%) developed ocular infections: Candida albicans endophthalmitis (2), Aspergillus fumigatus endophthalmitis (1), cytomegalovirus retinitis (4), herpes simplex virus keratitis (1), and varicella-zoster virus panophthalmitis (1). The mean time from OLT to ocular symptoms was 42 days for patients with fungal infections and 128 days for patients with viral infections. Blurred vision was the commonest symptom (five of nine cases). The mean duration of follow-up was 2 years (range, 33 days to 5 years). Permanent loss of vision occurred in three patients, five had improvement in visual acuity, and one died of disseminated aspergillosis 33 days after OLT. Infectious ocular complications following OLT may occur as isolated events or with disseminated disease. Fungal infections occur earlier (mean, 42 days after OLT) than viral infections (mean, 4 months after OLT). The clinical presentation may be atypical; aggressive vitreoretinal procedures and serial examinations may be required to establish the diagnosis. Cytomegalovirus retinitis in orthotopic liver transplant patients may not require life-long maintenance therapy with antiviral agents. 相似文献