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Biomedical subjects

M Garnier

Publications and source records attributed to M Garnier.

At least 91 records · Page 5Linked to original sources
PubMed1987

Osmotic properties of human erythrocytes treated by phospholipase A2 from bee venom.

During treatment of human red cells with phospholipase A2 from bee venom, a linear increase of the MCV and of the osmotic fragility occurs in parallel with the cleavage of the accessible phospholipids. However, even after maximal hydrolysis, i.e. degradation of up to 65% of the phosphatidylcholines and up to 6% of the phosphatidyl-ethanolamines, almost no haemolysis is observed and the median corpuscular fragility is only 7% higher than that of control cells incubated without enzyme. Addition of albumin to the medium results in an important rise of the susceptibility to hypotonic saline solutions. Osmotic fragility curves obtained with red cells submitted to mild phospholipase action show evidence of subpopulations of cells with various sensitivities to osmotic lysis. This phenomenon can be partly explained by the heterogeneity of the cleavage intensity among the cell population. This hypothesis is supported by the studies of the lipid composition of phospholipase treated red cells fractionated according to their sensitivity to hypotonic lysis or to their size.

Bee Venoms↗
PubMed1987

[Fibronectin in the ascitic fluid: its diagnostic significance].

We studied fibronectin concentration in the ascitic fluid of 102 patients, 71 with cirrhosis, 13 with hepatocellular carcinoma, 12 with malignant peritonitis, and six with miscellaneous disease. Fibronectin concentrations in the first three groups were 45 +/- 45 mg/l, 54 +/- 84 mg/l, and 144 +/- 123 mg/l, respectively. The difference between patients with cirrhosis and malignant peritonitis was significant (p less than 0.01). However, fibronectin concentration greater than 100 mg/l had a sensitivity of 58 per cent and a specificity of 86 per cent for the diagnosis of malignant peritonitis. Ascitic fluid protein content over 30 g/l had the same sensitivity and specificity was 90 per cent. Among cirrhotic patients, high fibronectin concentrations were demonstrated in those with long-standing ascites (m = 134 +/- 58 mg/l) whereas the lowest concentrations were found in patients with severe hepatocellular failure (m = 12 +/- 9 mg/l). Concentrations were significantly different, according to whether or not spontaneous bacterial peritonitis occurred later (20 +/- 13 mg/l versus 52 +/- 49 mg/l); 83 per cent of patients with spontaneous bacterial peritonitis during their clinical course had initial fibronectin concentrations above 30 mg/l in their ascites. We conclude that: 1) measurement of fibronectin concentration in ascitic fluid is of poor diagnostic value for discrimination between malignant and non malignant ascitic, 2) low concentrations of fibronectin are associated with the occurrence of spontaneous bacterial peritonitis in cirrhotic patients. Hypothetically, the quantitative defect of fibronectin could be responsible for bacterial opsonization impairment in these patients.

Ascitic Fluid↗
PubMed1987

Towards monoclonal antibodies against the apple proliferation mycoplasma-like organism.

A 6-week-old female BALB/c mouse was immunized with a preparation of partially purified sieve tubes of periwinkle (Catharantus roseus) plants infected with the apple proliferation mycoplasma-like organism. After fusion of the immunized spleen cells with myeloma cells, the supernatant fluids of the resulting hybridoma cultures were screened for the presence of antibodies in a differential avidin-biotin enzyme-linked immunosorbent assay (ELISA) using sieve tube preparations from either healthy or infected periwinkles as antigens. One hybridoma clone, giving a negative ELISA with the sieve tube preparation from healthy plants and a positive ELISA with that infected ones, was selected. This hybridoma also gave a negative ELISA when tested against sieve tube preparations from periwinkles affected by citrus greening or Spiroplasma citri, but a positive ELISA when tested against phyllody-affected sieve-tube preparations.

Antibodies, Bacterial↗
PubMed1986

Properties of rabbit erythrocytes treated with phospholipase A2 from bee venom.

In isotonic saline-buffered conditions, phospholipase A2 from bee venom cleaves up to 65% of the phosphatidylcholine of the rabbit RBC membrane without causing significant hemolysis; however, the volume and the osmotic fragility of the treated RBC is modified. The osmotic behaviour of PLA-treated RBC after reincubation in autologous plasma suggests an heterogeneity in the enzymatic attack among the RBC population. In vivo RBC survival is strongly impaired by PLA treatment.

Animals↗
PubMed1986

Plasma and erythrocyte lipid composition in normal pregnancy.

Variations of the plasma and erythrocyte lipid composition were studied in 110 clinically normal pregnant women at different gestational ages; a longitudinal study, carried out in 10 of these women, confirms the results of the cross-sectional study. The main changes observed in the plasma are a rise of the levels of triglycerides, phosphatidyl-cholines and to a lower extent of sphingomyelins; these increases are significantly correlated with the gestational age. The RBC lipid composition is faintly modified throughout pregnancy; the most important changes are observed close to term: after 35 weeks of gestation, the concentration of sphingomyelins, phosphatidyl-cholines and phosphatidyl-ethanolamines are higher and that of the cholesterol/phospholipids is lower than at the beginning of pregnancy. Modifications of some erythrocyte physical properties occurring in the course of gestation cannot mainly be attributed to variations of the membrane lipid composition.

Adult↗
PubMed1985

Purification and partial characterization of the extracellular gamma-D-glutamyl-(L)meso-diaminopimelate endopeptidase I, from Bacillus sphaericus NCTC 9602.

The gamma-D-glutamyl-(L)meso-diaminopimelate endopeptidase, or endopeptidase I, from Bacillus sphaericus 9602 was purified to apparent protein homogeneity. The purification was achieved by a six-step procedure: ammonium sulfate fractionation, phenyl-Sepharose chromatography, two consecutive DEAE-Trisacryl chromatographies, chromatofocusing and Sephacryl S-200 permeation chromatography. The enzyme was purified 5000-fold with a 38% recovery of lytic activity. It is an acidic protein (pI 5.4) of hydrophobic nature. Kinetic studies have shown a Km value of 0.57 mM and an apparent Vmax of 8.3 mumol min-1 (mg enzyme)-1 with N-acetylmuramyl-L-alanyl-gamma-D-glutamyl-(L)meso-diaminopimelyl (L)-D-[14C]alanine as substrate. The enzyme was inhibited by o-phenanthroline and EDTA and was reactivated by zinc, cobalt and manganese ions; thus endopeptidase I is a metallo enzyme, probably a zinc enzyme. Moreover it is a heat-stable protein with an apparent inactivation temperature of 80 degrees C.

Bacillus↗
PubMed1985

Characterization of "Campylobacter pyloridis" by culture, enzymatic profile, and protein content.

"Campylobacter pyloridis" has been recently described as a gastritis-associated bacterium. We studied 20 strains. The bacteria had most of the characteristics of Campylobacter spp. strains. They were hippurate negative and tolerant to triphenyl tetrazolium chloride (at 0.4 and 1 mg/ml). They grew on all the media commonly used in laboratories, although chocolate agar was the most effective for isolation. They grew in a microaerophilic atmosphere as well as in an atmosphere enriched in CO2 and when incubated at 37 degrees C but not at 30 or 42 degrees C. A total of 31 enzymes were present among the 78 studied. gamma-Glutamyl-transpeptidase activity was, in addition to urea hydrolysis, an interesting feature for the identification of these bacteria. The protein profiles of the 20 strains were similar.

Adult↗
PubMed1985

Sweat collection from athletes.

The difficulty in taking sweat during heavy physical exercise has drawn the authors into testing a technique of sampling generally used in paediatrics. The fact that the results, which have been dealt with statistically, should coincide with the physiological facts already published allows us to consider a use of the technique in order to investigate the physiological mechanisms in action during sweating under different metabolic conditions.

Adult↗
PubMed1984

Influence of heat and sodium dodecyl sulfate on the endopeptidase I from Bacillus sphaericus 9602.

Endopeptidase I from Bacillus sphaericus is a stable enzyme which retains its activity at 37 degrees C in the presence of sodium dodecyl sulfate. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed two forms of the enzyme: an active, fast-running form, for the enzyme preheated at 37 degrees C and a denatured, slow-running form, for the enzyme preheated at 100 degrees C. Such behavior is similar to that of the "heat-modifiable" outer membrane proteins from gram-negative bacteria. In the absence of sodium dodecyl sulfate, endopeptidase I aggregated in an enzymatically active dimer, with an apparent molecular weight of 90,000 daltons, which could be the native form of the enzyme.

Bacillus↗
PubMed1984

Relationship between the intra-erythrocyte sodium composition and the membrane lipoprotein composition among different mammal species.

Internal sodium and lipoprotein composition of RBCs of nine mammalian species are measured. A significant correlation can be demonstrated between the erythrocyte mean sodium value of studied species and the membrane protein/lipid ratio (r = 0.80, alpha less than 0.01). Erythrocyte internal sodium can be correlated with membrane-free cholesterol but not with the phospholipid fractions.

Animals↗
PubMed1984

Growth and division of Spiroplasma citri: elongation of elementary helices.

The smallest viable cell of Spiroplasma citri is a two-turn helix (elementary helix). This elementary helix grows into longer parental cells, which then divide by constriction. The helical morphology is conserved during this process. The growth pattern of S. citri membranes has been investigated by different methods of membrane labeling. When labeling is done with specific antibodies, a diffuse growth of the membrane is observed. On the contrary, pulse-labeling of the membrane with tritiated amino acids reveals a polar growth of the organism. Finally, labeling of oxydo reduction sites with potassium tellurite also indicates a polarity in the organism. These results are discussed, and a scheme for spiroplasma growth is proposed.

Amino Acids↗
PubMed1984

Discovery of a new plant-pathogenic spiroplasma.

To study natural transmission of Spiroplasma citri in the Mediterranean area, periwinkles (Vinca rosea L.) were exposed to natural infection in several locations during the summer of 1983. Detection of S. citri in the periwinkles was assayed by ELISA and culture of the organisms. Some of the periwinkles developed yellows disease symptoms; they contained helical organisms in their sieve tubes, as determined by electron microscopy. A spiroplasma could be cultured from them, but their ELISA reaction for S. citri detection was negative. These results suggested that a spiroplasma different from S. citri had been discovered. The apparently new spiroplasma (P40) was examined for serological relationships with other spiroplasmas by metabolism inhibition and deformation tests. Spiroplasma P40 was found to have relatedness only to Group I spiroplasmas. Healthy periwinkles graft inoculated with shoots of the initial symptomatic periwinkle showed yellows symptoms 3 months after inoculation. Extracts of the initial and the graft-inoculated periwinkles gave positive ELISA reactions with anti-P40 IgG.

Base Composition↗
PubMed1984

Characterization of spiroplasma virus group 4 (SV4).

Spiroplasma virus Group 4 was propagated, purified and characterized. The isometric capsid is made from one major protein of 60,000 Da and contains a circular single-stranded DNA molecule of 1.7 X 10(6) Da. The host-range of SV4 is limited to Subgroup I-2 spiroplasmas. The virions are released from the infected cells by a lytic process. Transfection of spiroplasmas of Subgroup I-2 by the viral DNA was demonstrated. A high efficiency of transfection was routinely obtained in the presence of polyethyleneglycol. These experiments indicate that spiroplasmas can absorb viral DNA, opening the way for cloning.

Bacteriophages↗
PubMed1984

Oxidoreduction sites and relationships of spiroplasmas with insect cells in culture.

We have previously shown that Spiroplasma citri oxidoreduction sites, as revealed by the reduction of potassium tellurite into electron-dense tellurium crystals detectable by electron microscopy, were located at the blunt end of the organisms. The time of incubation of S. citri in potassium tellurite had no influence on the labeling. We have investigated the presence and location of oxidoreduction sites for other spiroplasmas such as the corn stunt spiroplasma (CSS), 277F, B88, BNR1 and PPS1. For all of these strains (except CSS, which is similar to S. citri), the location of oxidoreduction sites was affected by the time of incubation in potassium tellurite, and could be observed in different locations of the helix. 277F showed first labeling at the blunt end and a second, strong labeling at the tapered end. The other strains showed labeling all along the helix, but labeling at the blunt end generally appeared first. When Drosophila (Dm-1) cell cultures were infected with S. citri or 277F, the organisms adsorbed to the cells. Observation of infected cells by electron microscopy revealed that S. citri attached to the cells by the blunt end, while 277F attached either by the blunt end or the tapered one. The infection of leafhopper cell cultures (AS-2) with S. citri has been followed by transmission electron microscopy after incorporation of tritiated thymidine in the organism, and an immunocytochemical method has been developed to locate the organisms inside the cells.

Animals↗