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Biomedical subjects

J Laporte

Publications and source records attributed to J Laporte.

At least 109 records · Page 6Linked to original sources
PubMed1978

The experimental production of diarrhoea in colostrum deprived axenic and gnotoxenic calves with enteropathogenic Escherichia coli, rotavirus, coronavirus and in a combined infection of rotavirus and E. coli.

We attempted to produce diarrhoea experimentally in the newborn calf by orally injecting 17 colostrum-deprived calves with two serotypes of Escherichia coli Ent+ K99+, a rotavirus and a coronavirus. With E. coli alone, a dose of 2 x 10(8) bacteria administered 24 hours after birth causes a mild attack of diarrhoea, whereas 1 x 10(10) bacteria leads to dehydration and death. An inoculation of rotavirus is followed by diarrhoea which always contains large quantities of rotavirus. These animals were anorectic for a time, but none was dehydrated or died. With coronavirus, there were large quantities of watery diarrhoea, which led to dehydration and death. The inoculation of rotavirus, not lethal in itself, followed by a similarly non lethal inoculation of E. coli in doses of 3 x 10(8) to 2 x 10(9) led to dehydration and death. The authors conclude that dehydration and death of the animal can caused by large doses of E. coli or coronavirus or by two non-lethal doses of rotavirus and E. coli administered one after the other.

Animals↗
PubMed1977

Caffeine, tobacco, alcohol and drug consumption among medical students in Barcelona.

A survey of medical students was conducted at the Universitat Autònoma de Barcelona in 1974. Out of 1029 students, 808 present at lectures (78.5%) returned properly completed questionnaires. These showed that mean caffeine consumption was 8.3 g per month and increased with the length of stay at the university. Tobacco consumption (general mean, 190 cigarettes per month, 216 for males and 150 for females) and alcohol consumption (8.8 litres/year for males and 4.1 litres/year for females) also increased with time spent at university. Alcohol consumption was not as high as in the general population. Amphetamine consumption was very high (22% of students had taken amphetamines on more than one occasion in the six months prior to the survey). Marihuana and hashish were by far the most commonly used drugs (9.6%), the use of these drugs being much less common than at other European universities. The use of "harder" drugs was very limited. Appraisal of alcohol, tobacco and amphetamine abuse is necessary, since the authorities have not employed adequate measures to stop or limit them.

Adult↗
PubMed1977

Yeast protoplasts from stationary and starved cells: preparation, ultrastructure and vacuolar development.

The conversion of stationary and starved yeast cells into protoplasts is described. The method is rapid, simple and can be applied to a variety of stationary yeast cells. Preincubation of yeast cells in the presence of pronase was essential for effective conversion into protoplasts. Baker's yeast and seven defined yeast strains, including one "petite", were studied. All of them were efficiently transformed into protoplasts in 60 to 90 min, depending on the strain culture conditions and the age of the culture. Protoplasts may be obtained even from late-stationary cells which contain spores. Saccharomyces cerevisiae cells subjected to complete starvation conditions in water, could also be completely transformed into protoplasts, even after 48 h of starvation. Electron microscope examination of stationary protoplasts from three different yeast strains showed no evidence of a remaining cell-wall. S. cerevisiae stationary cells show a very developed vacuolar system, a number of "lipid granules" and a few altered mitochondria. Endomycopsis fibuligera and Candida tropicalis stationary protoplasts show a similar fine structure, but "lipid granules" were completely absent.

Culture Media↗
PubMed1975

Nature of neuronal uptake and noradrenaline--adrenaline effects in the isolated rat vas deferens.

Uptake mechanisms in the rat vas deferens have not yet been thoroughly investigated. In this study we show that uptake inhibition by cocaine, amantadine and desmethylimipramine induces increases in sensitivity that are greater for adrenaline than for noradrenaline. However, this does not occur when guanethidine is used. These results are clearly in disagreement with the neuronal uptake hypothesis. Uptake mechanisms in the rat vas deferens may be different from those of other tissues.

Amantadine↗
PubMed1970

Isolation and properties of a temperature-sensitive sporulation mutant of Bacillus subtilis.

A thermosensitive sporulation mutant (t(s)-4) of Bacillus subtilis was isolated, and its morphological, physiological, and enzymatic properties were investigated. This mutant is able to grow equally well at 30 and 42 C, but is unable to sporulate at the higher temperature. Electron microscope studies have shown that the t(s)-4 mutant is blocked at stage zero of spore development. This was further confirmed by its inability to produce antibiotic when grown at the restrictive temperature and by the relatively low ribonucleic acid (RNA) and protein turnover during the stationary growth phase, characteristic for stage zero asporogenic mutants. At the permissive temperature, however, antibiotic production and RNA and protein turnover took place at the rate normally found in sporogenic strains of B. subtilis. The above properties were not altered in the parent strain when grown at either 30 or 42 C. By shifting cultures of the t(s)-4 mutant from 30 to 42 C and from 42 to 30 C at different stages of growth, we have been further able to show that the event affected at the high temperature takes place at a very early stage of spore development. As a consequence of this early block in the sporulation process, the t(s)-4 mutant grown at 42 C became defective in the late spore-specific enzymes involved in the biosynthesis of dipicolinic acid. This study suggests that the sporulation process is mediated by a regulatory protein which is altered in the thermosensitive mutant when grown at the restrictive temperature. As a result of this alteration, a pleiotropic phenotype is produced which has lost the ability to catalyze the late biochemical reactions required for spore formation.

Amino Acid Oxidoreductases↗