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Biomedical subjects

J M Alonso

Publications and source records attributed to J M Alonso.

At least 127 records · Page 7Linked to original sources
PubMed1989

Bordetella adenylate cyclase is a virulence associated factor and an immunoprotective antigen.

Bordetella pertussis and Bordetella parapertussis are both causative agents of whooping cough outbreaks. Although not expressing the pertussis toxin, B. parapertussis induces, in a murine model, an acute hemorrhagic edematous alveolitis, similar to that observed with B. pertussis. These data suggest that the pertussis toxin may only play an accessory role in the acute pulmonary syndrome observed during Bordetella infection. Both with B. pertussis and B. parapertussis, the ability to induce lethal pulmonary lesions is associated with enhanced in vitro adenylate cyclase expression and activity. We also demonstrate that passive immunization with specific anti-B. pertussis adenylate cyclase antibodies or active immunization with purified B. pertussis secreted adenylate cyclase protect mice against a lethal respiratory challenge with B. pertussis or B. parapertussis. Our results suggest that adenylate cyclase might be the primary cytotoxin responsible for mouse pulmonary lesions during respiratory tract infection with B. pertussis or with the related species B. parapertussis and is a protective antigen of B. pertussis.

Adenylyl Cyclases↗
PubMed1988

Involvement of the interleukin 2 pathway in the rearrangement and expression of both alpha/beta and gamma/delta T cell receptor genes in human T cell precursors.

In this report, we have undertaken the phenotypic, functional and molecular characterization of a minor (less than 5%) subpopulation of adult thymocytes regarded as the earliest intrathymic T-cell precursors. Pro-T cells were immunoselected and shown to express different hematopoietic cell markers (CD45, CD38, CD7, CD5) and some activation-related molecules (4F2, Tr, HLA class II), but lack conventional T cell antigens (CD2-1-3-4-8-). TCR-gamma RNA messages are already expressed at this early ontogenic stage, while alpha and beta chain TCR genes remain in germline configuration. In vitro analyses of the growth requirements of pro-T cells demonstrated the involvement of the IL-2 pathway in promoting their proliferation and differentiation into CD3+ CD4+ or CD8+ mature thymocytes. Moreover, during the IL-2-mediated maturation process rearrangements and expression of both alpha and beta chain TCR genes occurred, and resulted in the acquisition of alpha/beta as well as gamma/delta (either disulphide-linked or non-disulphide-linked) heterodimeric TCR among the pro-T cell progeny.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

Microheterogeneity and structures of neutral glycans present in quail ovomucoid.

Anionic chromatography of oligosaccharide-alditols obtained by alkaline hydrolysis of quail ovomucoid glycopeptides resulted in the isolation of a major neutral fraction (83%) which was separated into 14 fractions by high-performance liquid chromatography on an alkylamine silica column. The structures of nine oligosaccharide-alditols were determined. By the identification of mannobiosido-, and mannotriosido-di-N-acetylchitobiose mixed with N-acetyl-lactosaminic and oligomannosidic-types oligosaccharides, we demonstrate the high microheterogeneity of the glycans presents in the neutral fraction of this glycoprotein and suggest that ovomucoid glycosylation uses several pathways.

Animals↗
PubMed1988

Immunological consequences of HIV infection: advantage of being low responder casts doubts on vaccine development.

Immunosuppression in AIDS might be due to the immune response rather than to the pathogenicity of the virus. The basis of the immunosuppression could be molecular mimicries involving viral gp-110, CD4 molecules, antibodies, and CD4-acceptor sites. Whether an individual develops auto-immunosuppressive responses or mounts a harmless defence against (or coexists with) the virus follows the general rules of lymphocyte repertoire selection. MHC and V region genes and other polymorphic loci, together with the previous state of the immune system, particularly at early developmental periods, are factors that influence the response. Vaccination against gp 110-HIV might thus protect against infection but at the same time cause auto-immunosuppression and disease.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Continuous-flow fast atom bombardment-mass spectrometry of permethylated oligosaccharides: a comparative study of direct mixture analysis with packed capillary column liquid chromatography-fast atom bombardment-mass spectrometry.

Conventional positive fast atom bombardment (FAB) and continuous-flow FAB analysis were carried out with permethylated lacto-N-tetraose. This latter method, a new approach, has been used to analyze a mixture of permethylated oligosaccharides by liquid chromatography-mass spectrometry (LC-MS) with a packed capillary fused-silica column and the continuous-flow probe as interface. Under these conditions, we found the continuous-flow probe to be superior to the conventional probe because its low matrix level increased the signal-to-noise ratio. The analysis of the mixture of permethylated oligosaccharide alditols obtained from hen ovomucoid by LC-MS using the continuous-flow probe as interface is described.

Animals↗
PubMed1987

Failure of newer beta-lactam antibiotics for murine Yersinia enterocolitica infection.

Cefotaxime, imipenem, gentamicin, and doxycycline were active in vitro against the virulent serotype O8 Yersinia enterocolitica WA strain. Amoxycillin was inactive. The in vivo activity of these drugs was evaluated in a standardized and reproducible mouse model of systemic infection. Each single antibiotic was injected intravenously 30 h after intravenous inoculation of Y. enterocolitica WA. In vivo efficacy was measured by counting the viable bacteria recovered from the whole spleens of mice sacrificed at selected times. Doxycycline and gentamicin were active in stopping bacterial proliferation. Cefotaxime and imipenem, even at high doses (250 and 100 mg/kg of body weight, respectively), were totally ineffective, as was amoxycillin. Bacterial inocula (10(7)), recovered from either the in vitro growth or the infected spleens, were plated on cefotaxime or imipenem concentration gradients in agar; no emergence of beta-lactam-resistant organisms was detected. Based on these experiments it is not possible to explain, from any given property of the antibiotic, the bacteria, or the host, the discrepancy between the in vivo and in vitro activities of cefotaxime and imipenem. On the basis of these results, the use of newer beta-lactam antibiotics should be delayed in the therapy of human Y. enterocolitica infections until further investigations are carried out.

Amoxicillin↗
PubMed1987

Yersinia enterocolitica infection in pregnant mice and their offspring.

In order to investigate the susceptibility to Yersinia enterocolitica infection before and during pregnancy, and the potential vertical transmission to the offspring, female adult mice were intravenously inoculated with 3 x 10(4) CFU of Y enterocolitica either 7 days before conception or on day 8 of pregnancy. Infection was assessed by determining the number of bacterial counts in spleen of mothers, entire body of fetuses, placentas, and spleen of newborns. Mice challenged 7 days before pregnancy had cured at the time of mating. Pregnancy did not reactivate infection. In contrast, mice challenged at day 8 of pregnancy showed an intense reactivation of the splenic infection from day 15 of pregnancy to delivery. Moreover, they gave birth to live offspring, that were or were not infected, and to stillborn pups that were heavily infected. Splenic infection of mothers and living offspring that had been congenitally infected, cured by 8 days after delivery.

Animals↗
PubMed1986

Bordetella pertussis adenylate cyclase. Purification, characterization, and radioimmunoassay.

The extracellular adenylate cyclase of Bordetella pertussis was purified either as a free enzyme or as a complex with calmodulin. The purified enzyme has a specific activity of 1600 mumol of cAMP min-1 X mg-1 and exists under two molecular forms of 45 and 43 kDa which are apparently structurally related. Calmodulin increased considerably the resistance of adenylate cyclase to inactivation by trypsin. Although trypsin cleaved the adenylate cyclase-calmodulin complex, the digested fragments remained associated by noncovalent interactions in an active conformation. Specific mouse anti-adenylate cyclase antibodies inhibit adenylate cyclase activity and were used to develop a specific radioimmunoassay that allows detection of as little as 5 ng of adenylate cyclase in culture supernatants.

Adenylyl Cyclases↗
PubMed1986

Antagonism between Yersinia intermedia and Yersinia enterocolitica in water.

One strain of Yersinia enterocolitica and one strain of Y. intermedia were grown in peptone water at 25 or 37 degrees C, or in ground water at 15 degrees C. Similar growth rates were observed when these strains were cultivated separately in the same media and at the same temperature. Mixed cultures at 37 degrees C displayed equivalent growth rates. In contrast, mixed cultures incubated at 15 or 25 degrees C were regularly unfavourable to Y. enterocolitica, whereas they did not modify the growth of Y. intermedia. A bacteriophage active on Y. enterocolitica and not on Y. intermedia was characterized from the filtrate of mixed cultures at low temperatures. This phage produced by the lysogenic Y. intermedia strain might be a potential factor responsible for the inhibition of Y. enterocolitica, since no additional antibacterial factor or nutritional competition between Y. intermedia and Y. enterocolitica were found in the mixed cultures.

Antibiosis↗
PubMed1986

Kinetic properties of 5-carboxymethyl-2-hydroxymuconate semialdehyde dehydrogenase from Escherichia coli.

Kinetic properties of purified 5-carboxymethyl-2-hydroxymuconate semialdehyde (CHMSA) dehydrogenase (EC 1.2.1.-) in the 4-hydroxyphenylacetate meta-cleavage pathway from Escherichia coli have been studied. The temperature--activity relationship for the enzyme from 27 to 45 degrees C showed an Arrhenius plot with an inflexion at 36 degrees C. When 5-carboxymethyl-2-hydroxymuconic semialdehyde and NAD were used as variable substrates, the double reciprocal plots were all linear and the lines intersected at one point below the horizontal axis, suggesting that a sequential mechanism is operating. From the replots of intercepts and slopes against reciprocal substrate concentrations were calculated Km (CHMSA) = 9.0 +/- 1.02 microM, Km (NAD) = 29.1 +/- 4.65 microM and the value for the dissociation constant of enzyme--NAD complex = 6.3 +/- 1.21 microM. ATP and the product of the reaction (NADH) acted as competitive inhibitors of the enzyme with respect to NAD. Apparent Ki values, estimated from Dixon plots, were 25.0 +/- 3.5 and 88.0 +/- 22.1 microM for NADH and ATP, respectively.

Adenosine Triphosphate↗
PubMed1983

Simple method for demonstration of differential colony morphology of plasmid-associated virulent clones of Yersinia enterocolitica.

Virulent (plasmid-associated) strains of Yersinia enterocolitica grown on RPMI 1640 agar (RPMI-1640 medium [Flow Laboratories] with 40 mM HEPES and 1.5% [wt/vol] purified agar [Difco]) dissociated into small and large colonies. The autoagglutination test (a marker of virulence) is regularly positive with small colonies and negative with large colonies. Avirulent Y. enterocolitica strains gave only large colonies on RPMI 1640 agar.

Clone Cells↗