Biomedical subjects
Publications and source records attributed to R Lallier.
Cis- and Trans- dichlorodiammineplatinum (II) inhibit the development of the sea urchin eggs. The inhibition is prevented by N-acetylcysteine, glutathione and alpha-mercaptopropionylglycine. Sulfhydril groups appear as a cellular target for these platinum compounds.
In this study we used Escherichia coli strain F11(P155) of porcine origin. The heat-stable enterotoxin (ST) was produced with a batch fermentor under agitation (500 rpm) and forced aeration (5 liters/min) in Casamino Acids yeast extract medium containing 0.2% glucose. The pH varied from 7.2 to 7.8. The maximum amount of ST was obtained after 7 h of growth. ST was purified by ammonium sulfate precipitation, ultrafiltration on Amicon membranes, and chromatography in Bio-Gel P-4. The enterotoxin, which was purified approximately 1,000 times, was active at nanogram levels. On 20% polyacrylamide gel electrophoresis, ST exhibited an Rf of 0.6 ST was recovered from the gel slices by eluting in buffer and testing the activity in suckling mice, since no band appeared on the gel after staining with Coomasie brilliant blue R, Schiff reagent, or red oil. ST was resistant at pH 2 to 10 and at 100 degrees C for 15 min, but it was inactivated at 121 degrees C; it did not lose biological activity after treatment with pronase, lipase, or amylase. In suckling mice antiserum obtained from rabbits or goats immunized with ST neutralized the enterotoxin activity of a cell-free supernatant of purified ST.
Motile Aeromonas isolated from fish were studied for their virulence in fish in relation to some surface characteristics. The results showed that only the most virulent strains of A. hydrophila used in this study shared a common O antigen, did not agglutinate in acriflavine, settled down after boiling, and were resistant to the bactericidal action of fresh normal mammalian serum. The least virulent strains could not be grouped into this O antigenic group, they did not settle after boiling, and were sensitive to the bactericidal effect of serum. It is suggested that agglutination in acriflavine, stability after boiling, and sensitivity to normal fresh serum could be used for screening the Aeromonas isolates for virulence in fish.
Three groups of five piglets were formed and 1390 Escherichia coli isolates were obtained during the 45-day period of observation. One of the groups received feed without antibiotic whereas the second received feed containing 100 ppm neomycin and the third feed with 100 ppm neomycin plus 100 ppm tetracycline. Rectal swabbings for bacterial isolation were repeated ten times, twice during an adaptation period and eight times during the treatment period. Resistance among the isolates to tetracycline, streptomycin and triple sulfas remained high throughout this experiment whereas resistance to neomycin, chloramphenicol and ampicillin were found to increase significantly under the influence of antibiotic supplemented feed. This increase of antibiotic resistance was associated with an increase of the percentage of isolates harboring an R. factor. When comparing the ability of strains harboring an R factor to receive the plasmid Ent from the E. coli K12 (P155) with isolates not harboring such a plasmid, no significant difference was observed in their ability to receive the Ent plasmid.
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The action of BCG and LPS mR595 used in conjunction with a formula-defined diet is dependent on the administration timing and resembles that of interacting adjuvants affecting different elements of the immune system.
Trypsinized normal rat embryo fibroblasts and untrypsinized and trypsinized transformed rat fibroblasts have two orders of binding sites for bacterial glycolipid mR595. The high order sites fix 1--3 micrograms glycolipid mR595/10(5) cells and those of the low order fix about 6 microgram glycolipids mR595/10(6) cells. Ca++ is required for the low order glycolipid mR595 binding to be trypsinized but not to the untrypsinized transformed rat fibroblasts. The low order binding is temperature dependent with the transition temperature lying between 25 and 37 degrees C. Exogenously added ganglioside and glycoproteins contained in the fetal calf serum do not inhibit fixation of glycolipid mR595. Only beta-lipoprotein at high concentrations is slightly inhibitory. Glycolipid mR595 fixation to transformed fibroblast does not alter their morphology and appears to slightly improve cell attachment to substratum. Glycolipid mR595 fixation results in a lengthening of the S-phase of the cell cycle and a reduction in 2-deoxyglucose uptake. Uptake of inorganic phosphate is not affected. Inhibition of phospholipid synthesis is observed in mR595 fixed fibroblasts whereas synthesis of cell surface glycoproteins and the content of cellular gangliosides is not affected.
Two agents, dimethylmaleic anhydride and a polyaldehyde, capable of reacting with amino groups at the surface of the eggs of sea urchin do not prevent fertilization.
We have examined the content and permeability of chloride in sea urchin eggs. After fertilization there is a large increase in the permeability to chloride. We discuss the mechanism underlying this permeability change and the generalized increase in ion permeability observed after fertilization.
Evaluation of the Escherichia coli population in the small intestine of diarrheic calves was performed by estimating the number of colony-forming units and the observation of direct gram-stained smears of mucosal scrapings. Enterotoxigenicity of the isolates was determined by the infant mouse test and the ligated intestinal segment in calves. The influence of various broth culture media on the production of enterotoxin was also studied. Serologic characterization of the E coli isolates was performed. A total of 190 cases of diarrhea in bovine neonates was studied and it was found that enteropathogenic E coi was not responsible for more than 20% of the cases. A practical approach for the recognition of enteropathogenic E coli in a routine diagnostic laboratory is proposed.
Three lipopolysaccharides (LPS) of different chain length were used as adjuvant. The one of shortest chain length is the most effective in enhancing antibody titer in rats against sheep red blood cells, suggesting that lipid A and KDO were responsible for the stimulatory effect of LPS.
Tunicamycin, an inhibitor of glycoprotein synthesis, inhibits the development of the sea Urchin egg. Gastrulation is very sensitive to the Tunicamycin. Fertilization is not inhibited. 2-deoxy-D-glucose inhibits gastrulation and induces the hyperdevelopment of ectodermic structures.
The nature of the cell surface constituent(s) containing sialic acid that block fixation of bacterial glycolipid mR595 to normal rat fibroblasts was explored. Indirect evidence suggests that a trypsin-sensitive, high molecular weight glycoprotein, present in larger amounts on the surface of normal cells (as compared with transformed rat fibroblasts), may be involved as a blocking agent.
A whole cell lysate preparation of the Escherichia coli strain F11(P155) was treated with the following agents: heat (60 degrees C for 30 minutes), pronase, lipase, amylase, formalin (0.1%), sodium lauryl sulfate (0.05%) and sarkosyl NL30 (0.05%). Except for the amylase treatment, the treated whole cell lysate was inactivated when tested in rabbit gut loops or on Chinese hamster ovary cells. The preparations treated with heat or formalin could be used to produce a neutralizing antiserum or could remove the neutralizing capacity of an anti-F11(P155) serum. Finally, the attempt to demonstrate enterotoxicity with the cytoplasmic membrane of the bacterial cell failed.
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The analysis of sea urchin egg fertilization shows that several phenomena common to other biological systems are involved: cell recognition, cell fusion, exocytosis and initiation of mitotic activity. Both the role of calcium ions in cell fusion and exocytosis and the function of the cell surface in the initiation of mitotic activity appear to have general applicability. The study of fertilization can contribute to the elucidation of these processes and, reciprocally, progress in this field can help to advance our understanding of the mechanisms of fertilization in sea urchins and other organisms.
A formula-defined diet (diet 3, table 1) acted as an adjuvant as an adjuvant in the response of the immune system to SRBC in the rat. Similar minimum and maximum antibody levels were measured in both males and females. In the males, the maximum was reached with diet 3 alone while females required the complementary action of diet 3 and LPS mR 595.
This paper reports two different enterotoxigenic classes of the genus Aeromonas isolated from fishes. Strains of A. sobria were isolated from healthy fishes only wheras strains of A. hydrophila were isolated from both healthy and moribund fishes. Aeromonas sobria and hydrophilia strains produced a cytotoxic factor and were highly proteolytic. Seventy-five percent (75%) of the A. sobria strains produced only one type of hemolysis on 5% blood agar, but 92% of the A. hydrophilia produced two types of hemolysis. Enterotoxigenicity of all strains was tested by the rabbit gut loop technique and the suckling mouse test. Most of those Aeromonads were enterotoxigenic. Enterotoxigenic strains appeared to produce two different enterotoxins which were antigenically related, but they seemed to have different mechanisms of action. Enterotoxins of Aeromonas were shown to be antigenically different from those of E. coli.