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Biomedical subjects

J M Alonso

Publications and source records attributed to J M Alonso.

At least 145 records · Page 8Linked to original sources
PubMed1982

Carboxymethylhydroxymuconic semialdehyde dehydrogenase in the 4-hydroxyphenylacetate catabolic pathway of Escherichia coli.

5-Carboxymethyl-2-hydroxymuconic semialdehyde dehydrogenase in the 4-hydroxyphenylacetate meta-cleavage pathway has been purified to 96% homogeneity. The native enzyme, which appears to be a tetramer, has an apparent molecular weight of 210000. The purified enzyme shows a narrow pH optimum at pH 7.8 and does not require ions for its catalytic activity. Under standard assay conditions the enzyme acts preferentially with NAD but reduces NADP at 11% of the rate observed for NAD, primarily because of a difference in Km. Apparent Km values are 6.4 micro M for 5-carboxymethyl-2-hydroxymuconic semialdehyde and 52.2 micro M for NAD.

Aldehyde Oxidoreductases↗
PubMed1982

Temperature-modulated immunogenicity to Yersinia pestis from Yersinia enterocolitica O3.

The ability of Yersinia enterocolitica O3, grown at 25 degrees C, to promote cross-immunity to Y. pestis was lost after repeated subcultures at 37 degrees C, which selected for bacterial populations having lower in vivo survival. Subculturing Y. enterocolitica O3 from 37 to 25 degrees C restored the cross-immunogenicity although the in vivo survival remained low.

Animals↗
PubMed1981

New waterborne bacteriophages active on Yersinia enterocolitica.

Seven bacteriophages active on Yersinia enterocolitica (YE) were isolated from surface water samples collected in Granada, Spain. A comparison of the respective host ranges of these new phages and of reference phages used for YE phage typing showed that YE strains belonging to various phage types, grown at either 37 or 25 degrees C, expressed susceptibility to reference sewage water phages whereas susceptibility to new waterborne phages, as well as to reference phages from lysogenic YE, was only demonstrated in YE strains grown at 25 degrees C. A YE strain isolated by stool culture from a pig was lysogenic for a bacteriophage which behaved like waterborne phages and reference phages from lysogenic YE strains. The possibility that the isolation of waterborne bacteriophages might, in certain circumstances, reflect the presence of lysogenic YE was raised.

Animals↗
PubMed1981

Delayed-type hypersensitivity and acquired resistance to plague in mice immunized with killed Yersinia pestis and immunoregulators.

A simple reproducible footpad assay of delayed-type hypersensitivity (DTH) to Yersinia pestis was studied in mice immunized with 5 x 10(7) heat killed (HK) Y. pestis alone or in conjunction with Freund's complete adjuvant (FCA), cyclophosphamide (CY), BCG, or both CY and BCG. The footpad reaction elicited with 5 x 10(6) HK Y. pestis was shown to peak at 24 hr, was transferable with immune T lymphocytes but not with serum and had the classical DTH histology, The highest level of DTH occurred 6 or 8 days after immunization, according to the immunomodulator used, and immunized mice were therefore challenged with viable Y. pestis at this time. No correlation was found between DTH level and resistance of mice; only groups immunized under the potentiating effect of BCG used alone or with CY were significantly protected against Y. pestis. Control groups pretreated with BCG or BCG pretreated and immunized with a large dose of an unrelated gram negative bacterium were as susceptible to Y. pestis infection as normal mice. To promote this protective immunity, BCG and HK Y. pestis, must be injected in an area that drains to a common lymph node. No antibody to Y. pestis was found in immunized protected mice pretreated with BCG and CY and a very low antibody titre was found in immunized mice pretreated only with BCG. This serum was unable to confer resistance on recipient mice but immune cell transfer decreased the number of Y. pestis counted in the spleens of recipients 36 hr after challenge.

Animals↗
PubMed1979

Yersinia enterocolitica among small wild mammals in France.

A survey of Yersinia enterocolitica was made in two French areas (Indre and Alsace) in several components of the terrestrial ecosystem. Y. enterocolitica has been isolated from several habitats and from numerous species of small mammals. The trap line method enabled us to estimate the density of the two abundant small mammal species, Microtus arvalis and Apodemus sylvaticus, and the densities of Y. enterocolitica carriers. The frequency of isolation was high when temperatures were low, but did not seem to be in direct relationship with animal densities. Infectious lesions were never found in spleens or intestines of 1893 captured animals. Samples of fresh water, fresh-water fish, soil and earthworms were occasionally collected. A total of 163 strains were isolated. Of these, 99 were of biochemical type 1; 20 different 0 serogroups were found.

Animals↗
PubMed1979

Contribution to the definition and the taxonomy of Yersinia enterocolitica.

The phenotypic study of 6,000 strains of Y. enterocolitica and Y. enterocolitica-like organisms by the biochemical reaction of the identification of Enterobacteriaceae on one hand and of 100 strains representing different chemiotypes by an auxanogram technique shows a large homogeneity of these strains which are apparated from the other Yersinia within Enterobacteriaceae. Six chemiotypes are described. The strains fermenting thamnose, similar to chemiotype I, can be subdivided in two groups according to the acidification of melibiose. The future and the denomination of these strains are discussed. The biochemical characteristics difining Y. enterocolitica and six chemiotypes are defined.

Ampicillin↗
PubMed1979

Cellular depletion in Peyer's patches after cyclophosphamide treatment in mice.

The cytotoxic effects of cyclophosphamide (CY) in mice given by the intravenous route at the dose of 200 mg per kg of body weight, were investigated in Peyer's patches comparatively with peripheral blood and mesenteric lymph node as well as changes in the spleen weight. Peyer's patches are the sites of a more intense and durable cellular depletion than the mesenteric lymph node, observed as soon as day 1. A partial restauration of cell populations was observed from the 9th day, but even at day 21 their number remained lower than in control mice. Histological studies failed to show any germinal centre throughout the experiment; just a few cells were observed, 2 days after CY injection, in the interfollicular areas in which cells in mitosis were only seen at day 7. This preliminary results allow to study the role of the Peyer's patches as first barrier against penetration of an enteropathogenic bacteria able to invade the host tissues through the intestinal wall components after local or general acquired immunodeficiency.

Animals↗
PubMed1978

[Experimental infection in mice with Yersinia enterocolitica (strain biotype 4, serogroup O:3, phage type VIII): growth of the inoculum in athymic or cyclophosphamide treated mice (author's transl)].

Intravenous infection of Swiss mice with a strain of Yersinia enterocolitica unable to colonize normal mice by the oral route, induced a systemic infection. Viable bacteria were isolated from homogenates of liver, spleen and lungs, as early as one hour after the challenge and have been detected during two weeks. On the other hand, the number of viable bacteria isolated from the blood has always been very low. Faecal samples permitted the isolation of Y. enterocolitica even after two weeks, while at this time no more bacteria were isolated from the tissues. The duration of the infection remained unchanged with an inoculum of 10(3), 10(4) or 10(5) viable bacteria. Depending on the size of the inoculum, liver macroscopic abscesses occurred more or less rapidly after the challenge. These abscesses disappeared spontaneously. A single intravenous injection of cyclophosphamide (200 mg/kg) six days after the challenge was followed by an important rise of the number of bacteria in all the tissues. Comparative studies of intravenously infected athymic (Nude) mice and controls showed a higher number of bacteria in the liver and spleen of the athymic animals.

Animals↗
PubMed1975

[Experimental pathogenicity of "Yersinia enterocolitica" for athymic nude mice (author's transl)].

Amongst the 4,500 strains of our collection of Yersinia enterocolitica usually non-pathogenic for laboratory animals, 5 or 6 strains appeared to be naturally pathogenic for mice. Using these strains and non-pathogenic strains representing more than 90 per cent of human isolates in the world (biotype 4, serotype 0:3, phagocyte VIII; biotype 2, serotype 0:9, phagotype X3), the pathogenicity for cyclophosphamid treated mice and athymic Nude mice has been tested. Highly pathogenic strains killed conventional as well as cyclophosphamid treated mice. Non-pathogenic strains for conventional mice did not show any pathogenicity for cyclophosphamid treated mice (strain IP161 excepted) but killed 30 athymic Nude mice inoculated with 5 x 10(8) and 5 x 10(5) organisms by the oral or intraperitoneal routes. Nude mice infected intragastrically or intraperitoneally showed signs of enteritis and bronchopneumonia followed by a septicemia. Abscesses were found in the liver, the spleen and the ileal wall. The infection of Nude mice with Y. enterocolitica resembles naturally acquired human infection where 2/3 of the cases are enteritis among under 4-year-old children and where septicemia occurs among immunologically deficient adults. The role of T-lymphocytes and of immune functions in Y. enterocolitica infection is discussed through our model.

Animals↗