烫伤、内毒素对豚鼠胃肠动力影响的实验研究

目的:探讨烫伤后胃肠动力障碍发生机制.方法:豚鼠30只,随机分为烫伤、内毒素及对照组,在烫伤及内毒素腹腔注射1小时后测定豚鼠胃肠推进距离、肠道组织降钙素基因相关肽(CGRP)、Na -K 、Mg2 、Ca2 、及Ca2 -Mg2 -ATP酶含量.结果:①烫伤及内毒素组肠道推进功能受到抑制,烫伤组抑制更明显.②烫伤及内毒素组CGRP含量较对照组增多,烫伤组增高幅度更明显.③烫伤及内毒素组豚鼠肠道组织中各ATP酶的含量较对照组明显减少,两组ATP酶减少程度无明显差异.结论:①烫伤及内毒素抑制豚鼠的肠道推进功能,烫伤比内毒素组抑制更明显.②烫伤及内毒素组CGRP含量较对照组明显增多,烫伤组CGRP增高幅度更明显.③烫伤及内毒素组各ATP酶的含量较对照组减少,烫伤组、内毒素组各ATP酶减少程度无明显差异.     

Purification and characterization of human endopeptidase 3.4.24.16. Comparison with the porcine counterpart indicates a unique cleavage site on neurotensin

We have purified and characterized human brain endopeptidase 3.4.24.16. The enzyme behaved as a 72 kDa protein and belonged to the metalloprotease family. Human endopeptidase 3.4.24.16 cleaved neurotensin at a unique site at the Pro¹⁰-Tyr¹¹ bond, leading to the formation of neurotensin(1–10) and neurotensin(11–13). The kinetic parameters displayed by human endopeptidase 3.4.24.16 towards a series of natural neuropeptides indicated that bradykinin was the most efficiently proteolysed. Angiotensin I, dynorphins 1–8 and 1–9 and substance P also behaved as good substrates while neuromedin N, angiotensin II, leucine and methionine enkephalin and neurokinin A resisted degradation by human endopeptidase 3.4.24.16. We have purified the porcine counterpart of endopeptidase 3.4.24.16 and compared its ability to cleave neurotensin with that of the enzyme from human origin. It appeared that, besides a major production of neurotensin(1–10), an additional formation of neurotensin(1–8) was observed with the pig enzyme, suggesting a cleavage of neurotensin not only at the Pro¹⁰-Tyr¹¹ bond but also at the Arg⁸-Arg⁹ peptidyl bond. The latter cleavage appeared reminiscent of endopeptidase 3.4.24.15 since this peptidase was reported to cleave neurotensin at the Arg⁸-Arg⁹ bond. Our study indicated that neurotensin(1–10) formation by porcine endopeptidase 3.4.24.16 could be potently blocked with the selective endopeptidase 3.4.24.16 dipeptide inhibitor Pro-Ile without interfering with neurotensin(1–8) formation. By contrast, the formation of the latter product was highly potentiated by dithiothreitol and inhibited by the endopeptidase 3.4.24.15 inhibitor Cpp-Ala-Ala-Tyr-pAB, two effects that were not observed for neurotensin(1–10) production. Altogether, our results indicate that porcine endopeptidase 3.4.24.16 cleaves neurotensin at a unique site, leading to the formation of rteurotensin(1–10) and that the production of neurotensin(1–8) is due to contaminating endopeptidase 3.4.24.15.     

An analysis of methylphenidate induced gnawing in guinea pigs

20 compounds acting on the central nervous system and the autonomic nervous system were tested in guinea pigs for their ability to induce gnawing. Only methylphenidate induced vigorous gnawing similar to that produced by apomorphine and amphetamine. Methylphenidate differs in its mode of action from both apomorphine and amphetamine. In the guinea pig, phenylethyl configuration with OH groups at para and meta positions of the phenyl ring does not seem to be an essential criterion for inducing gnawing as suggested for the rat (Ernst, 1965). Catecholamines do not appear to play any significant role in the mediation of methylphenidate gnawing, or even in the gnawing response itself in guinea pigs, since increase in the level of dopamine and other catecholamines does not induce gnawing.Communication No. 1394 of Central Drug Research Institute, Lucknow, India.     

Kinetic determination of malate dehydrogenase isozymes

These studies determine the levels of malate dehydrogenase isoenzymes in cardiac muscle by a steady state kinetic method which depends on the differential inhibition of these isoenzyme forms by high concentrations of oxaloacetate. This inhibition is similar to that exhibited by lactate dehydrogenase in the presence of high concentrations of pyruvate. The results obtained by this method are comparable in resolution to those obtained by CM-Sephadex fractionation and by differential centrifugation for the analyses of mitochondrial malate dehydrogenase and cytoplasmic malate dehydrogenase in tissues. The use of standard curves of percent inhibition of malate dehydrogenase activity plotted against the ratio of mitochondrial MDH activity to the total of mMDH and cMDH activities [$\text{m}\text{(m + c)}$ malate dehydrogenase ratio] (percent m-type) is introduced for studies of comparative mitochondrial function in heart muscle of different species or in different tissues of the same species.     

Absorption of enterally administered N-acetyl-l-glutamine versus glutamine in pigs

BACKGROUND AND AIMS: Glutamine instability in liquid media suggests that evaluation of reasonable enteral nutrition sources of glutamine is needed. N-acetyl-l-glutamine offers no instability and no intolerance problems. This research was conducted to study the absorption and apparent digestibility of glutamine versus N-acetyl-l-glutamine. METHODS: Two pig models were used. (1) In a clamped jejunal loop experiment, we measured the concentrations of glutamine and N-acetyl-l-glutamine in the intestinal infused solutions, intestinal mucosa, and portal and peripheral blood. (2) In a feeding experiment, we determined their apparent digestibility. RESULTS: N-acetyl-l-glutamine ( approximately 76%) was slightly less absorbed than glutamine ( approximately 85%) from the intestinal lumen into mucosa, where it was not detected as intact molecule, suggesting almost complete hydrolysis during absorption. Virtually no intact N-acetyl-l-glutamine was observed in the blood compartments; glutamine from lumenal N-acetyl-l-glutamine had the same behavior as that from lumenal-free glutamine in portal and peripheral blood. The apparent ileal digestibility of N-acetyl-l-glutamine was lower than that of free glutamine, as N-acetyl-l-glutamine was probably retained in the intestinal lumen to a greater extent than glutamine. CONCLUSION: N-acetyl-l-glutamine appeared to be a good candidate for glutamine fortification of enteral nutrition formulas.     

Oral immunization of piglets with recombinant F4 fimbrial adhesin FaeG monomers induces a mucosal and systemic F4-specific immune response

The importance of adhesins in the pathogenicity of several bacteria resulted in studies on their usefulness in vaccines. In this study, the gene of the F4(K88)-fimbrial adhesin FaeG of the pathogenic enterotoxigenic Escherichia coli (ETEC) strain GIS26 was cloned in the pET30Ek-LIC vector and expressed with an N-terminal His- and S-tag in the cytoplasm of BL21(DE3). Recombinant FaeG (rFaeG) subunits were isolated from insoluble cytoplasmic aggregates and refolded into a native-like F4 receptor (F4R)-binding conformation. Indeed, the presence of conformational epitopes was shown by ELISA and the ability to bind the F4R was observed by inhibiting the adhesion of F4+ ETEC to F4R+ villi with increasing concentrations of native-like refolded rFaeG subunits. The rFaeG subunits appear as monomers, whereas the purified F4 fimbriae are multimers. Oral immunization of newly weaned piglets with native-like rFaeG induced a mucosal and systemic F4-specific immune response, significantly reducing F4+ E. coli excretion from 2 till 5 days following challenge infection. However, improvement of stability and immunogenicity of rFaeG is necessary since a higher F4-specific response was obtained following immunization with purified F4 fimbriae. Furthermore, the N-terminal fusion of a His- and S-tag was not detrimental for binding the F4R, supporting the use of FaeG as mucosal carrier. In conclusion, oral immunization with a recombinant fimbrial adhesin subunit of Escherichia coli induces a mucosal and systemic fimbriae-specific immune response.     

"Porcine bronchus" diagnosed in neonatal period

“Porcine bronchus” is a right upper lobe bronchus arising directly from the trachea. This is an infrequent congenital abnormality and it usually represents the displaced origin of a normal bronchus. We herewith report a case of a child who was diagnosed to have tracheal bronchus in neonatal period and followed subsequently until 13 months of age.     

合肥市屠宰生猪主要微生物学指标调查研究

目的：了解合肥市定点屠宰场生猪屠宰加工产品的卫生质量以及加工生产的卫生状况。方法：应用国标法对5个定点生猪屠宰场500份生猪胴体体表样品及200份胴体肉样进行菌落总数、大肠菌群和沙门菌的检测。结果：生猪胴体肉样菌落总数和大肠菌群的总超标率达46%和22.5%;生猪胴体体表样品和肉样沙门菌检出率分别为24.2%和17%;大肠菌群和沙门菌之间呈现正相关。结论：合肥市生猪胴体的卫生质量急需提高,屠宰生产加工水平亟待改善,在肉品生产过程中重视大肠菌群的控制则有利于降低沙门菌的污染程度,实施宰前管理和宰前检验是保证病健隔离分宰,减轻对加工环境和产品污染的重要环节。     

A regenerative erythropoietic response does not increase the frequency of Pig‐a mutant reticulocytes and erythrocytes in Sprague‐Dawley rats

The in vivo rodent Pig‐a mutation assay is a sensitive test to identify exposure to mutagenic substances, and has been proposed as an assay for the identification of impurities for pharmaceuticals. Red blood cells (RBCs) and reticulocytes (RETs) are analyzed by flow cytometry after exposure to potentially mutagenic chemicals for cells deficient in the cell surface anchored protein CD59, representing mutation in the X‐linked Pig‐a gene. The full potential of the assay as well as its limitations are currently being explored. The current study investigated the effects of regenerative erythropoietic bone marrow responses on the frequency of Pig‐a mutated reticulocytes (RET^CD59‐) and erythrocytes (RBC^CD59‐). We hypothesized that a robust regenerative erythropoietic response would not increase the basal frequency of RET^CD59‐ or RBC^CD59‐ cells. Two groups of six male Sprague‐Dawley rats either had 2 mL of blood sampled each day via an indwelling catheter over a period of 5 days or were minimally sampled for hematology and used as controls. Blood was also then collected and evaluated 5, 18, and 49 days after the initial bleed period for the number of Pig‐a mutant cells in either the RET or RBC population. Despite the expected decrease in hematocrit and the correlative increase in reticulocytes after bleeding, no increase in the number of Pig‐a mutant cells was observed in male Sprague‐Dawley rats that were bled for five consecutive days. These results indicate that changes in erythropoiesis and hematology parameters in rats appear to have no effect on the background levels of Pig‐a mutated RETs and RBCs. Environ. Mol. Mutagen. 59:91–95, 2018. © 2017 Wiley Periodicals, Inc.     

VERIFICATION OF LEWISITE EXPOSURE BY THE ANALYSIS OF 2-CHLOROVINYL ARSONOUS ACID IN URINE

Verification of lewisite (L) exposure aids in the proper medical treatment of personnel who have come into contact with this vesicant. The purpose of this study was to develop a method for the detection of 2-chlorovinyl arsonous acid (CVAA) in theurine of guinea pigs exposed toL. Guinea pigs weresubcutaneously (sc)injected at 500 mug/kg with L in sesame seed oil. Urine samples were collected and analyzed at 8-h intervals for 40 h. CVAA is the hydrolysis product that retains most of L's structure. Two gas chromatographic methods of detection, mass spectrometry (MS) and atomic emission spectroscopy (AES), were employed to detect CVAA derivatized with ethanedithiol (EDT). CVAA-EDT was more amenable to gas chromatographic separation than was CVAA. Samples of urine were extracted with C-18 solid-phase cartridges, eluted with methanol, dried, derivatized with EDT, and analyzed. CVAA-EDT was detected at 3-mug/mL concentrations in 0- to 8-h samples and 100-ng/mL concentrations in 16- to 24-h samples. Results indicate that CVAA can be detected in guinea pig urine up to 24 h after subcutaneous L exposure using either MS or AES detectors. Demonstration of CVAA in guinea pig urine following sc injection with L suggests that its presence in human urine would prove exposure to L.