Biomedical subjects
Publications and source records attributed to C Bon.
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Snake venom serine proteinases affect many steps of the blood coagulation cascade. Each of them usually acts selectively on one coagulation factor. They are therefore potentially useful components to study the mechanisms of action, the regulation and the structure-function relationships of human serine proteinase coagulation factors. This strategy is illustrated for a plasminogen activator purified from Trimeresurus stejnegeri venom.
Some venom and mammalian-secreted phospholipases A(2) (sPLA(2)) have been described to exert an anticoagulant effect. This review will discuss and compare phospholipid-dependent versus protein-dependent mechanisms of action of these sPLA(2) on the coagulation cascade. The importance of venom proteins, and of the study of their pharmacological effects, to explore the physiological functions of homologous mammalian proteins is also pointed out.
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Acid-base state and oxygenation of fetal blood were evaluated in a group of 73 appropriate for gestational age fetuses between 17 and 41 weeks of gestation; fetal blood was obtained by cordocentesis. We measured, on umbilical venous blood, pH, pCO2, bicarbonates and total CO2, pO2 and percent oxygen saturation; we obtained following results: pH = 7.309 +/- 0.054; pCO2 = 5.99 +/- 0.85 kPa; HCO3 = 22.16 +/- 1.90 mmol/l; total CO2 = 22.53 +/- 1.97 mmol/l; pO2 = 6.02 +/- 1.68 kPa; SaO2 = 0.71 +/- 0.18. In comparison with adult normal values, our results report in fetuses a frequent state of mild and mixed acidosis (in about 80% of cases), rather gazeous; pH is significantly correlated with pCO2 (r = -0.799), moreover there is also a metabolic origin in acidosis. We observed progressive modifications of acid-base state and oxygenation in fetal blood with advancing gestational age: decrease of pH and pO2, increase of pCO2 and bicarbonates; these changes appear mainly from 35th week of gestation, except for bicarbonates, which increase regularly during gestational period we have studied. Fetal acid-base state may be explained by physiological differences due to fetal life conditions, in comparison with adult life conditions. Results obtained in this population of normal fetuses can be considered as reference values for studied parameters.
We have studied the value of decarboxyprothrombin assay, in association with that of alpha-foeto-protein (AFP), for the biological diagnosis of hepatocellular carcinoma. Levels of decarboxyprothrombin and AFP were measured in 60 patients divided into two groups: 37 patients with hepatocellular carcinoma from liver cirrhosis, confirmed by histology; 23 patients with liver cirrhosis, but having not developed hepatocellular carcinoma. The cirrhosis was in most of cases consecutive to hepatitis B or hepatitis C infection, or of alcoholic origin. Levels of decarboxyprothrombin were also determined in a control group of 50 healthy subjects. Plasma decarboxyprothrombin concentrations were measured by enzyme immunoassay. All normal subjects had levels of decarboxyprothrombin below 2 micrograms/l. Out of 37 patients with hepatocellular carcinoma, 24 (64.9%) showed elevated decarboxyprothrombin levels, while this marker was increased only in 26% of cirrhotic patients. Decarboxyprothrombin and AFP levels are elevated in 48.6% of hepatocellular carcinoma, normal in 16.2% of hepatocellular carcinoma and dissociated in 35.2% of cases; respectively 18.9% and 16.2% of patients with hepatocellular carcinoma have either high AFP level or high decarboxyprothrombin level. The simultaneous determination of decarboxyprothrombin and AFP appear to be useful, since the combination of the two markers allows the detection of 83.8% of hepatocellular carcinoma, while the detection rate is only 67.5% with using AFP alone. No significant correlation was observed between plasma decarboxyprothrombin and serum AFP levels.
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