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221.
222.
Beh?et's disease is characterized by recurrent aphthous stomatitis, uveitis, genital ulcers, and skin lesions. The role of
the HLA-B*51 gene has been confirmed in recent years, although its contribution to the overall genetic susceptibility to Beh?et's disease
was estimated to be only 19%. The production of a variety of cytokines by T cells activated with multiple antigens has been
shown to play a pivotal role in the activation of neutrophils. As regards the treatment, anti-tumor necrosis factor alpha
therapy has been shown to be effective for mucocutaneous symptoms as well as for sight-threatening panuveitis, although a
randomized, controlled trial is required. 相似文献
223.
Inhibitors of angiotensin-converting enzyme containing a tetrahedral arsenic atom. 总被引:1,自引:1,他引:0 下载免费PDF全文
A series of tetrahedral oxo acids of Group VA and VIA elements and of silicon and boron were examined as inhibitors of angiotensin-converting enzyme. Arsenate is a competitive inhibitor with a Ki of 27 +/- 1 mM, at least 10-fold more potent than phosphate. Dimethylarsinate is a competitive inhibitor with a Ki of 70 +/- 9 mM, 2-fold more potent than dimethylphosphinate. Oxo acids of boron, silicon, antimony, sulphur and selenium are not inhibitors. On the basis of these results and the strong inhibition of this zinc metallopeptidase by substrate analogues containing a tetrahedral phosphorus atom, two substrate analogues containing a tetrahedral arsenic atom were prepared. 2-Arsonoacetyl-L-proline is a competitive inhibitor with a Ki of 18 +/- 7 mM, more than 2000-fold weaker than that of its phosphorus analogue 2-phosphonoacetyl-L-proline. 4-Arsono-2-benzylbutanoic acid is a mixed inhibitor with a Ki of 0.5 +/- 0.2 mM, indistinguishable in potency from its phosphorus analogue 2-benzyl-4-phosphonobutanoic acid. 相似文献
224.
Excessive intake of essential elements agitates elemental homeostasis resulting in their heterogeneous distribution. Distraction
of these elements in central nervous system (CNS) have been demonstrated in many neurological disorders, which are vital in
generating free radicals, causing oxidative stress, and contributing to neuronal maladies. The developing CNS is highly vulnerable
to environmental agents, including fluoride. Fluorosis is one such disorder ensued from excessive consumption of fluoride
containing water and/or foods that poses a greater threat to the life. Present study offers perturbations caused by fluoride
toxicity on the level of biometal and antioxidant homeostasis and their interactions. Pregnant Wistar rats were exposed to
100- and 200-ppm fluoride (F−) in drinking water and controls with tap water. The pups born to them were used for the study. On 21st postnatal day, the
concentration of fluoride, biometals, and oxidative stress markers were determined in discrete regions of CNS. The levels
of fluoride, copper, and iron increased whereas manganese and zinc were decreased considerably. Among antioxidant enzymes,
catalase, superoxide dismutase, and glutathione peroxidase were decreased and lipid peroxidation was increased with regional
alterations. The correlation coefficient values among oxidative stress markers and biometals were either positive or negative
and showed less significance during correlation. The results confirm that the fluoride provoked oxidative stress and biometal
deformations are synergistic that successively governs the neuronal damage and developing CNS no longer prevents exacerbations
of fluoride. 相似文献
225.
Molecular cloning of cis-acting regulatory alleles of the Bacillus subtilis amyR region by using gene conversion transformation. 总被引:5,自引:5,他引:0 下载免费PDF全文
Three cis-acting alleles (gra-10, gra-5, and amyR2) of the Bacillus subtilis amyR promoter locus each cause catabolite repression-resistance of amyE-encoded alpha-amylase synthesis. The gra-10, gra-5, and amyR2 alleles were transferred from the chromosomes of their respective hosts to a plasmid carrying the amyR1-amyE+ gene by the process of gene conversion which is carried out during transformation of competent B. subtilis by plasmid clones carrying homologous DNA. The cloned amyR promoter regions containing the gra-10 and gra-5 mutations were shown to confer catabolite repression-resistance in cis to the synthesis of chloramphenicol acetyltransferase encoded by the cat-86 indicator gene when subcloned into the promoter-probe plasmid pPL603B. Implications concerning both the regulation of amyR utilization and the process of gene conversion in B. subtilis are discussed. 相似文献
226.
The RNA helicases encoded by melanoma differentiation-associated gene 5 (mda-5) and retinoic acid-inducible gene I (RIG-I) detect foreign cytoplasmic RNA molecules generated during the course of a virus infection, and their activation leads to induction of type I interferon synthesis. Paramyxoviruses limit the amount of interferon produced by infected cells through the action of their V protein, which binds to and inhibits mda-5. Here we show that activation of both mda-5 and RIG-I by double-stranded RNA (dsRNA) leads to the formation of homo-oligomers through self-association of the helicase domains. We identify a region within the helicase domain of mda-5 that is targeted by all paramyxovirus V proteins and demonstrate that they inhibit activation of mda-5 by blocking dsRNA binding and consequent self-association. In addition to this commonly targeted domain, some paramyxovirus V proteins target additional regions of mda-5. In contrast, V proteins cannot bind to RIG-I and consequently have no effect on the ability of RIG-I to bind dsRNA or to form oligomers. 相似文献
227.
Seasonal changes in the ruminal microflora of the high-arctic Svalbard reindeer (Rangifer tarandus platyrhynchus). 总被引:9,自引:7,他引:2 下载免费PDF全文
The dominant rumen bacteria in high-arctic Svalbard reindeer were characterized, their population densities were estimated, and ruminal pH was determined in summer, when food quality and availability are good, and in winter, when they are poor. In summer the total cultured viable population density was (2.09 +/- 1.26) X 10(10) cells ml-1, whereas in winter it was (0.36 +/- 0.29) X 10(10) cells ml-1, representing a decrease to 17% of the summer population density. On culture, Butyrivibrio fibrisolvens represented 22% of the bacterial population in summer and 30% in winter. Streptococcus bovis represented 17% of the bacterial population in summer but only 4% in winter. Methanogenic bacteria were present at 10(4) cells ml-1 in summer and 10(7) cells ml-1 in winter. In summer and winter, respectively, the proportions of the viable population showing the following activities were as follows: starch utilization, 68 and 63%; fiber digestion, 31 and 74%; cellulolysis, 15 and 35%; xylanolysis, 30 and 58%; proteolysis, 51 and 28%; ureolysis, 40 and 54%; and lactate utilization, 13 and 4%. The principal cellulolytic bacterium was B. fibrisolvens, which represented 66 and 52% of the cellulolytic population in summer and winter, respectively. The results indicate that the microflora of the rumen of Svalbard reindeer is highly effective in fiber digestion and nitrogen metabolism, allowing the animals to survive under the austere nutritional conditions typical of their high-arctic habitat. 相似文献
228.
Location within a tree was analyzed as a source of variation in Sequoia sempervirens leaf monoterpenes. No differences were found for quantitative composition or total yield/dry wt among lower, middle and upper canopy positions. The awlshaped, spirally arranged leaves of vigorous upper shoots showed small quantitative compositional differences, but not differences in total yield. The intermediate leaf form of young sprouts had the most different monoterpene quantitative composition and about three times the total yield of the above two leaf forms. Analysis of a clonal ring of 17 adult trees resulted in coefficients of variation similar to those for samples collected from different canopy levels of the same shoot. Results revealed the sources and magnitudes of experimental error in comparative studies of this species' leaf monoterpenes, and did not support the concept that somatic mutation provides an important source of variation in a large, long-lived organism such as coast redwood. 相似文献
229.
Inducibility of metallothionein throughout the cell cycle. 总被引:1,自引:0,他引:1
Synchronized Chinese hamster cells were induced with ZnCl2 at multiple stages of the cell cycle and labeled with [35S]cysteine, and the 35S-labeled proteins were isolated and separated into metallothionein and nonmetallothionein fractions. Metallothionein was found to be inducible in all stages of the cell cycle and in G1-arrested cells. 相似文献
230.
Use of Metabolic Inhibitors to Estimate Protozooplankton Grazing and Bacterial Production in a Monomictic Eutrophic Lake with an Anaerobic Hypolimnion 总被引:15,自引:8,他引:7 下载免费PDF全文
Inhibitors of eucaryotes (cycloheximide and amphotericin B) and procaryotes (penicillin and chloramphenicol) were used to estimate bacterivory and bacterial production in a eutrophic lake. Bacterial production appeared to be slightly greater than protozoan grazing in the aerobic waters of Lake Oglethorpe. Use of penicillin and cycloheximide yielded inconsistent results in anaerobic water and in aerobic water when bacterial production was low. Production measured by inhibiting eucaryotes with cycloheximide did not always agree with [3H]thymidine estimates or differential filtration methods. Laboratory experiments showed that several common freshwater protozoans continued to swim and ingest bacterium-size latex beads in the presence of the eucaryote inhibitor. Penicillin also affected grazing rates of some ciliates. We recommend that caution and a corroborating method be used when estimating ecologically important parameters with specific inhibitors. 相似文献