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排序方式: 共有678条查询结果,搜索用时 15 毫秒
21.
Vasoactive intestinal peptide (VIP) caused a dose-dependent fall in lower esophageal sphincter (LES) pressure and dose-dependent contractions in the body of the esophagus. The response to VIP in the esophagus or LES was not modified by atropine, phentolamine, haloperidol, pyrilamine, methysergide, indomethacin and tetrodotoxin, showing that it exerts direct action at the esophageal smooth muscle. These studies suggest that VIP causes contraction in the esophageal body and relaxation of the LES by a direct action on the smooth muscle. It is possible that VIP may be the common mediator of noncholinergic, nonadrenergic neurons that cause relaxation of the lower esophageal sphincter and contraction in the esophageal body. 相似文献
22.
Land treatment of wastewater is an attractive alternative to conventional sewage treatment systems and is gaining widespread acceptance. Although land application systems prevent surface water pollution and augment the available water supplies, the potential dangers to human health should be evaluated. Since sewage may contain high amounts of bacterial endotoxin, the removal of endotoxin from sewage by percolation through soil was investigated. It was found that 90 to 99% of the endotoxin was removed after travel of sewage through 100 to 250 cm of loamy sand soil. When distilled water was allowed to infiltrate into the soil to simulate rainfall, the endotoxin was mobilized and moved in a concentrated band through the soil column. On testing samples from actual land treatment sites, as much as 480 ng of endotoxin per milliliter was found in some groundwater samples. The presence of endotoxin in potable water is known to be a potential problem under some circumstances, but the importance of endotoxin in water supplies has not been fully assessed. Therefore, the design, operation, and management of land application systems should take into account the fate of endotoxin in groundwater beneath the sites. 相似文献
23.
S R Farrah C P Gerba S M Goyal C Wallis J L Melnick 《Applied and environmental microbiology》1977,33(2):308-311
Pleated cartridge filters are capable of concentrating enteroviruses from large volumes (well over 2,000 liters) of tap water. These epoxy-fiberglass filters can be regenerated if they are treated with 0.1 N NaOH or autoclaved to inactivate any contaminating virus. The regenerated filters regained their ability to concentrate viruses from water at high flow rates. 相似文献
24.
Carbon Oxysulfide Inhibition of the CO(2)-Concentrating Process of Unicellular Green Algae 总被引:1,自引:0,他引:1 下载免费PDF全文
Carbonyl sulfide (COS), a substrate for carbonic anhydrase, inhibited alkalization of the medium, O2 evolution, dissolved inorganic carbon accumulation, and photosynthetic CO2 fixation at pH 7 or higher by five species of unicellular green algae that had been air-adapted for forming a CO2-concentrating process. This COS inhibition can be attributed to inhibition of external HCO3− conversion to CO2 and OH− by the carbonic anhydrase component of an active CO2 pump. At a low pH of 5 to 6, COS stimulated O2 evolution during photosynthesis by algae with low CO2 in the media without alkalization of the media. This is attributed to some COS hydrolysis by carbonic anhydrase to CO2. Although COS had less effect on HCO3− accumulation at pH 9 by a HCO3− pump in Scenedesmus, COS reduced O2 evolution probably by inhibiting internal carbonic anhydrases. Because COS is hydrolyzed to CO2 and H2S, its inhibition of the CO2 pump activity and photosynthesis is not accurate, when measured by O2 evolution, by NaH14CO3 accumulation, or by 14CO2 fixation. 相似文献
25.
R M Wright M D Yablonsky Z P Shalita A K Goyal D E Eveleigh 《Applied and environmental microbiology》1992,58(11):3455-3465
Genomic DNA fragments encoding beta-glucosidase activities of the thermophilic actinomycete Microbispora bispora were cloned into Escherichia coli. Transformants expressing beta-glucosidase activity were selected by their ability to hydrolyze the fluorogenic substrate 4-methylumbelliferyl-beta-D-glucoside. Two genes encoding beta-glucosidase activity were isolated and distinguished by restriction analysis, Southern hybridization, and the substrate specificities of the encoded enzymes. One gene, bglB, encoded a beta-glucosidase that was expressed intracellularly in E. coli. It exhibited a molecular mass of approximately 52,000 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) and 51,280 Da by nondenaturing gradient PAGE, a pI of 4.6, and temperature and pH optima of 60 degrees C and 6.2, respectively. Cloned BglB showed greater activity against cellobiose than against aryl-beta-D-glucosides and was thermostable, retaining about 70% of its activity after 48 h at 60 degrees C. BglB activity is activated two- to threefold in the presence of 2 to 5% (0.1 to 0.3 M) glucose. The DNA sequence of the 2.2-kb insert carrying bglB has been determined. An open reading frame which codes for a protein of 473 amino acids with a predicted molecular mass of 52,227 Da showed significant homology (40 to 47% identity) with beta-glucosidases from glycosal hydrolase family 1. 相似文献
26.
C J Hurst S A Schaub M D Sobsey S R Farrah C P Gerba J B Rose S M Goyal E P Larkin R Sullivan J T Tierney et al. 《Applied microbiology》1991,57(2):395-401
Two candidate methods for the recovery and detection of viruses in soil were subjected to round robin comparative testing by members of the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group. Selection of the methods, designated "Berg" and "Goyal," was based on results of an initial screening which indicated that both met basic criteria considered essential by the task group. Both methods utilized beef extract solutions to achieve desorption and recovery of viruses from representative soils: a fine sand soil, an organic muck soil, a sandy loam soil, and a clay loam soil. One of the two methods, Goyal, also used a secondary concentration of resulting soil eluants via low-pH organic flocculation to achieve a smaller final assay volume. Evaluation of the two methods was simultaneously performed in replicate by nine different laboratories. Each of the produced samples was divided into portions, and these were respectively subjected to quantitative viral plaque assay by both the individual, termed independent, laboratory which had done the soil processing and a single common reference laboratory, using a single cell line and passage level. The Berg method seemed to produce slightly higher virus recovery values; however, the differences in virus assay titers for samples produced by the two methods were not statistically significant (P less than or equal to 0.05) for any one of the four soils. Despite this lack of a method effect, there was a statistically significant laboratory effect exhibited by assay titers from the independent versus reference laboratories for two of the soils, sandy loam and clay loam. 相似文献
27.
28.
Capture of latex beads, bacteria, endotoxin, and viruses by charge-modified filters. 总被引:6,自引:6,他引:0 下载免费PDF全文
This report demonstrates how electropositive filters can be used to enhance the removal of microorganisms and other negatively charged particles from water. It was shown that electropositive depth filters were capable of adsorbing viruses and endotoxins many times smaller than the average pore size of the filter. Electronegative filters of similar porosity or electropositive filters that had been treated to destroy the positive charge were almost ineffective under similar conditions for the removal of viruses and small latex spheres. The results of this study indicate that electropositive filters are highly effective in the removal of a wide range of contaminants over a wide range of pH values and ionic conditions. 相似文献
29.
Kaur Jaspreet Kumar Vikas Sharma Kartik Kaur Sawinder Gat Yogesh Goyal Ankit Tanwar Beenu 《International journal of peptide research and therapeutics》2020,26(1):33-41
International Journal of Peptide Research and Therapeutics - Bioactive peptides have been reported to exhibit opioid-like activity and are termed as opioid peptides. Either these are produced... 相似文献
30.
Goyal Khushboo Kaur Kamaljit Kaur Gurjit 《Physiology and Molecular Biology of Plants》2020,26(5):899-906
Physiology and Molecular Biology of Plants - The effect of potassium nitrate on the status of fermentative and sucrose metabolizing pathways was studied in two maize (Zea mays L.) genotypes, viz.,... 相似文献