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Immunomodulation of Electrical and Synaptic Behavior of Myenteric Neurons of Guinea Pig Small Intestine During Infection with Trichinella Spiralis
Published in William J. Snape, Stephen M. Collins, Effects of Immune Cells and Inflammation on Smooth Muscle and Enteric Nerves, 2020
Neurons were exposed to pharmacological agents, neurotransmitter substances and a saline-extracted somatic protein antigen from Trichinella larvae by (1) addition to the physiological salt solution (Krebs-Ringer bicarbonate) perfusing the recording chamber, and (2) ejection from pipettes (5–10 um diameter) onto the ganglionic surface. The somatic antigen was prepared according to previously described procedures25 from infective larvae collected from skeletal muscle and the protein content determined by the method of Bradford26. Antigenicity of somatic protein was determined by an agar immunodiffusion technique27.
Shigella
Published in Dongyou Liu, Laboratory Models for Foodborne Infections, 2017
Soumik Barman, Yoshifumi Takeda
For daily laboratory screening of shigellae, two different selective media are generally used, namely Hektoen enteric (HE) agar and xylose lysine desoxycholate (XLD) agar. Shigella colonies on XLD agar appear translucent, pink, or red and are smooth in nature. S. dysenteriae 1 colonies on XLD agar are commonly very small, unlike those of other Shigella species.23 Colonies of shigellae on HE agar appear green. Serological identification by slide agglutination with polyvalent somatic antigen grouping sera further confirms the serotypes and subserotypes.
Endotoxin: Historical Perspectives
Published in Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison, Endotoxin in Health and Disease, 2020
Ernst T. Rietschel, Otto Westphal
In the 1940s, Walther F. Goebel (Fig. 9) in New York, working with Shigella sonnei and Shigella flexneri, showed together with Chloe Tal that bioactive preparations contained a firmly bound component, which he called toxic component T (51). By mild acid treatment he obtained haptenic O-specific polysaccharide (Morgan’s degraded polysaccharide) and a toxic protein: protein T (Morgan’s conjugated protein). In contrast, by alkaline treatment and alcoholic fractionation he was able to isolate an O-antigenic, toxic polysaccharide (polysaccharide T) and nontoxic protein (Morgan’s simple protein). In the O-antigenic complex, therefore, the component T appeared to form the link between O-antigenic polysaccharide and protein, so that, depending on the dissociation procedure, Goebel obtained two different toxic substances in which T was either bound to polysaccharide or to protein. The chemical nature of compound T, however, remained obscure and turned out only much later to be identical with the bioactive principle of endotoxin, i.e., the lipid A component. Goebel and coworkers termed the bioactive material obtained from S. flexneri (52,53) toxic carbohydrate (CT) and that isolated from S. sonnei lipo-carbohydrate (54). Another interesting aspect of these bacterial antigens was described in 1934 by Gough and Frank M. Burnet (55). These authors had isolated bacterial extracts consisting mainly of polysaccharide. They showed that this polysaccharide fraction was important not only for its serological properties but also—and this was new—for the phage susceptibility of bacteria. As the biological activity of the polysaccharide material was destroyed by alkali, it is certain that the authors worked with O-antigen or “somatic antigen” as they discussed in their revealing study.
Epidemiology of Shiga toxin-producing Escherichia coli O157:H7 in Africa in review
Published in Southern African Journal of Infectious Diseases, 2018
Like any other member of the family Enterobacteriaceae, Shiga toxin-producing Escherichia coli O157:7 can be isolated on MacConkey agar, followed by conventional biochemical or serological tests to confirm that the isolates are E. coli. Isolation can also be done by use of sorbitol MacConkey agar whereby most STEC O157:H7 are distinguished from other strains by their inability to ferment sorbitol. Direct inoculation of a sample on sorbitol MacConkey agar has been employed, but has been proven to be less sensitive compared to immunomagnetic separation.56,57 Some studies have employed both sorbitol MacConkey agar and immunomagnetic separation to maximise the chances of isolating the pathogen.32 STEC O157:H7 strains should be distinguished from Non-O157:H7 strains, which also do not ferment sorbitol.18 Either of these E. coli isolation options can be accomplished by performing an agglutination test using antibodies against a somatic antigen for O157:H7 and a flagella antigen for H7. Polymerase chain reaction (PCR) for the detection of shiga toxin-producing genes in E. coli O157:H7 remains a gold standard detection method.57 Detection of the bacteria or toxins may take more than 24 h.58 In some instances, DNA hybridisation has been performed to affirm additional virulence genes and phenotypic activities of shiga toxin-producing genes proven by Vero-cell cytotoxicity assay.