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91.
J L Young D R Pendergast J Steinbach 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1991,196(1):61-68
The purpose of this investigation was to evaluate the impact of long-term diabetes on muscle blood flow (MBF) and oxygen transport (vO2) during exercise. Twelve male patients (58 +/- 8 years, mean +/- SD), with at least a 10-year history of diabetes controlled by insulin, and seven age-matched controls (56 +/- 5 years, mean +/- SD) participated in this study. No patient had been clinically diagnosed as having peripheral vascular disease, and on the average resting ankle/arm systolic blood pressure ratios were normal. Following a baseline period, 5 min of cycle ergometer exercises at 75 W were performed in the upright position and, after 1-hr recovery, in the supine position. Continuous vO2 was determined via breath-by-breath analysis. MBF was measured in the vastus lateralis (VL) and tibialis anterior (TA) by 133Xe clearance. In the erect position, the diabetic group (compared with the control group, respectively) exhibited significantly (P less than 0.05) lower exercise MBF [ml. (100 g.min)-1] in both VL (19 +/- 2.5 vs 30.9 +/- 2) and TA (13.7 +/- 2 vs 22.0 +/- 4), a lower steady-state VO2 (1.3 +/- 0.3 vs 1.7 +/- 0.2 liters.min-1) during exercise including the values in the last 15 sec of exercise, and greater accumulation of blood lactate (35 +/- 2 vs 22.0 +/- 2 mg/100 ml). The same trends in the data were observed during supine exercise; however, the blood pressure of the diabetics was significantly elevated during exercise when compared with that of controls. The reduced exercise MBF in the TA and VL demonstrated that impaired microvascular flow, without clinically overt peripheral vascular disease, in long-term diabetics leads to reduced oxygen delivery and exercise tolerance. 相似文献
92.
Degradation of toluene and m-xylene and transformation of o-xylene by denitrifying enrichment cultures 总被引:2,自引:0,他引:2
Seven different sources of inocula that included sediments, contaminated soils, groundwater, process effluent, and sludge were used to establish enrichment cultures of denitrifying bacteria on benzene, toluene, and xylenes in the absence of molecular oxygen. All of the enrichment cultures demonstrated complete depletion of toluene and partial depletion of o-xylene within 3 months of incubation. The depletion of o-xylene was correlated to and dependent on the metabolism of toluene. No losses of benzene, p-xylene, or m-xylene were observed in these initial enrichment cultures. However, m-xylene was degraded by a subculture that was incubated on m-xylene alone. Complete carbon, nitrogen, and electron balances were determined for the degradation of toluene and m-xylene. These balances showed that these compounds were mineralized with greater than 50% conversion to CO2 and significant assimilation into biomass. Additionally, the oxidation of these compounds was shown to be dependent on nitrate reduction and denitrification. These microbial degradative capabilities appear to be widespread, since the widely varied inoculum sources all yielded similar results. 相似文献
93.
Anaerobic degradation of toluene by a denitrifying bacterium 总被引:12,自引:0,他引:12
A denitrifying bacterium, designated strain T1, that grew with toluene as the sole source of carbon under anaerobic conditions was isolated. The type of agar used in solid media and the toxicity of toluene were determinative factors in the successful isolation of strain T1. Greater than 50% of the toluene carbon was oxidized to CO2, and 29% was assimilated into biomass. The oxidation of toluene to CO2 was stoichiometrically coupled to nitrate reduction and denitrification. Strain T1 was tolerant of and grew on 3 mM toluene after a lag phase. The rate of toluene degradation was 1.8 mumol min-1 liter-1 (56 nmol min-1 mg of protein-1) in a cell suspension. Strain T1 was distinct from other bacteria that oxidize toluene anaerobically, but it may utilize a similar biochemical pathway of oxidation. In addition, o-xylene was transformed to a metabolite in the presence of toluene but did not serve as the sole source of carbon for growth of strain T1. This transformation was dependent on the degradation of toluene. 相似文献
94.
Co-localization of nitric oxide synthase immunoreactivity and NADPH diaphorase staining in neurons of the guinea-pig intestine 总被引:1,自引:0,他引:1
H. M. Young J. B. Furness C. W. R. Shuttleworth D. S. Bredt S. H. Snyder 《Histochemistry and cell biology》1992,97(4):375-378
Summary Neuronal nitric oxide synthase (NOS), an enzyme capable of synthesizing nitric oxide, appears to be identical to neuronal NADPH diaphorase. The correlation was examined between NOS immunoreactivity and NADPH diaphorase staining in neurons of the ileum and colon of the guinea-pig. There was a one-to-one correlation between NOS immunoreactivity and NADPH diaphorase staining in all neurons examined; even the relative staining intensities obtained were similar with each technique. To determine whether pharmacological methods could be employed to demonstrate that NADPH diaphorase staining was due to the presence of NOS, tissue was pre-treated with NG-nitro-l-arginine, a NOS inhibitor, or l-arginine, a natural substrate of NOS. In these experiments on unfixed tissue, it was necessary to use dimethyl thiazolyl tetrazolium instead of nitroblue tetrazolium as the substrate for the NADPH diaphorase histochemical reaction. Neither treatment caused a significant decrease in the level of NADPH diaphorase staining, implying that arginine and NADPH interact at different sites on the enzyme. 相似文献
95.
Primary structure of a protein isolated from reef shark (Carcharhinus springeri) cartilage that is similar to the mammalian C-type lectin homolog, tetranectin. 总被引:1,自引:0,他引:1
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P. J. Neame C. N. Young J. T. Treep 《Protein science : a publication of the Protein Society》1992,1(1):161-168
During the course of characterization of low molecular weight proteins in cartilage, we have isolated a protein from reef shark (Carcharhinus springeri) cartilage that bears a striking resemblance to the tetranectin monomer originally described by Clemmensen et al. (1986, Eur. J. Biochem. 156, 327-333). The protein was isolated by extraction of neural arch cartilage with 4 M guanidine hydrochloride, dialysis of the extract to bring the guanidine to 0.4 M (reassociating proteoglycan aggregates), followed by cesium chloride density gradient removal of the proteoglycans. The amino acid sequence had 166 amino acids and a calculated molecular weight of 18,430. The shark protein was 45% identical to human tetranectin, indicating that it was in the family of mammalian C-type lectins and that it was likely to be a shark analog of human tetranectin. The function of tetranectin is unknown; it was originally isolated by virtue of its affinity for the kringle-4 domain of plasminogen. Sequence comparison of human tetranectin and the shark-derived protein gives clues to potentially important regions of the molecule. 相似文献
96.
The histological inspection of tumor tissue for the purpose of reporting a tumor grade is a problem of significant clinical importance. The grading by a pathologist is only partly reproducible due to vaguely defined, subjective criteria. In this article we describe and evaluate a set of measurable features that quantitate the differences in tumor tissue. Different aspects of the reproducibility of the measurements under varying conditions of image selection, focus, and noise have been investigated. Three hundred thirty-three images were digitized from 111 bladder tissue sections (4 microns thick, Feulgen stained), using the ICAS microscope-camera platform. A segmentation routine was developed to segment the images into nuclei and background without any user interaction. Size, shape, optical density, and texture features were measured on and among the objects found by this segmentation routine using the image analysis package Acuity. The results of the measurements showed that there is a significant quantitative difference between grade 1 and grade 3 tumors. Grade 2 tumors can be described as "in between grade 1 and grade 3" and falling somewhere on an increasing scale between grades 1 and 3. Grade 2 tumors do not seem to represent a statistically distinct population. The procedure described here is shown to be quite reproducible in the presence of noise, reasonably reproducible in the event of a modest amount of defocusing (with grade 3 tumors exhibiting the most sensitivity), and less reproducible in the context of which fields-of-view are chosen for analysis. 相似文献
97.
Transcription from the adenovirus major late promoter uses redundant activating elements 总被引:3,自引:0,他引:3
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The adenovirus major late promoter (MLP) has been analyzed by constructing recombinant viral genomes containing mutations in possible promoter elements. Single base pair changes in the TATA box had no effect on viral replication, and MLP expression, as measured by the accumulation of late mRNAs, was at wild type levels. However, a double mutation in the TATA box reduced viral replication and MLP expression, demonstrating that the TATA box is important, although not essential, for maximal activity in virus. Primer extension analysis showed that the mRNAs were initiated at the correct position. A mutation in the CAAT box was viable, and had only minor effects on MLP expression. However, this mutation when coupled to a single mutation in the TATA box, severely reduced viral replication and expression from the MLP. Similarly, a viable mutation in the UPE, shown previously to abolish binding of USF, coupled to a single mutation in the TATA box was lethal. These results suggest that both USF and the CAAT box binding factor CP1 can interact with TFIID to effect activation, and thus that the mechanism of activation is functionally redundant. 相似文献
98.
A protein antigen of Mycobacterium leprae is related to a family of small heat shock proteins. 总被引:15,自引:4,他引:11
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A H Nerland A S Mustafa D Sweetser T Godal R A Young 《Journal of bacteriology》1988,170(12):5919-5921
The gene encoding an immunologically important 18-kilodalton protein antigen of Mycobacterium leprae has been sequenced, and the amino acid sequence of the antigen has been deduced. The 18-kilodalton antigen is strikingly similar in size and sequence to a family of eucaryotic heat shock proteins. 相似文献
99.
100.
Isolation and partial characterization of an ion channel protein from human sperm membranes 总被引:1,自引:0,他引:1
G P Young S S Koide M Goldstein J D Young 《Archives of biochemistry and biophysics》1988,262(2):491-500
Human sperm cells were fractionated and plasma membrane proteins were separated by molecular gel sieving chromatography (Sephacryl S-200 followed by HPLC). A pore-forming protein was extracted from sperm cell membranes. The partially purified protein migrated with Mr 100,000-110,000, as determined by molecular sieving gel chromatography, and with a Mr 90,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. The channel activity was also extracted with Triton X-114, suggesting a hydrophobic nature for this protein. This protein was incorporated into planar lipid bilayers, resulting in the formation of voltage-dependent ion channels. Single channel fluctuations of 130 pS/unit in 0.1 M NaCl were resolved; however, channels preferentially aggregated in triplets having an open state life-time that persisted for several seconds. The channels studied here were more selective for monovalent cations than anions, but also showed some permeability to anions and larger electrolytes, suggesting a large functional pore diameter. The role of this sperm channel in normal sperm physiology and/or fertilization is presently unclear. 相似文献