The use of Dispholidus typus venom in elucidating the cause of a low prothrombin index

A biochemical and pharmacological examination of Rhamphiophis oxyrhynchus (Rufous beaked snake) venom

The venom of R. oxyrhynchus, a member of the psammophiine subfamily of the colubrid assemblage, was examined for biological activity using biochemical and pharmacological techniques. Venom displayed a high protein content, a complex electrophorectic profile and PLA2 activity but no detectable proteolytic or haematological activities. In the chick biventer cervicis nerve muscle preparation, venom (1-10 microg/ml) displayed postsynaptic neurotoxic activity as evidenced by inhibition of indirect (0.1 Hz, 0.2 ms, supramaximal V) twitches and responses to exogenous acetylcholine (1 mM) and carbachol (20 microM). This inhibitory effect was poorly reversible by washing. Venom (30-50 microg/ml) caused a rapid and readily reversible inhibition of direct (0.1 Hz, 2 ms, supramaximal V) twitches of the chick biventer cervicis nerve muscle preparation without morphological changes to the muscle fibers. Venom (30-100 microg/ml) inhibited electrically-evoked (0.2 Hz, 0.3 ms, 70-100 V) twitches of the prostatic segment of the rat vas deferens. This inhibitory effect was not significantly attenuated by 8-phenyltheophylline (8-PT; 20 microM), idazoxan (1 microM), a combination of ranitidine (0.2 microM) and thioperamide (10 microM) or capsazepine (10 microM). Venom (5 mg/kg) induced hypotension with subsequent cardiovascular collapse in the anaesthetised rat. The cardiovascular collapse was prevented by artificial respiration of the animals prior to venom administration. The biological activities demonstrated by R. oxyrhynchus venom may aid in prey envenomation strategies such as prey immobilisation. This study provides further evidence that colubrid venoms are comprised of multiple components which can display a variety of actions, some of which may be novel, therefore reinforcing the largely untapped potential of colubrid venoms.

A comparison between des-gamma-carboxy prothrombin and alpha-fetoprotein as markers of hepatocellular carcinoma in southern African blacks

Des-gamma-carboxy prothrombin (DCP), a precursor of prothrombin, has been reported recently to be as good a marker, or even better, of hepatocellular carcinoma than alpha-fetoprotein (alpha-FP). The sensitivity, specificity and predictive values of the two markers have been compared in 98 southern African Blacks with hepatocellular carcinoma and in 120 Black controls with various diseases which might be mistaken clinically for this tumour: 32 with hepatic metastases, 33 with amoebic hepatic abscesses, and 55 with chronic hepatic parenchymal disease. DCP levels were measured using a chromogenic assay with Dispholidus typus venom and staphylocoagulase. The agreement between the two methods was excellent (r = 0.995). alpha-FP concentrations were measured by radioimmunoassay. DCP levels were raised in 66 of 98 patients (67.3%) and alpha-FP levels in 82 of 98 patients (83.7%) with hepatocellular carcinoma (P = 0.006). The specificity of DCP was also less than that of alpha-FP, although the difference just failed to reach statistical significance (P = 0.085). The predictive values of both a positive and a negative test for DCP were significantly less than those for alpha-FP (P = 0.047 and 0.048, respectively). When, in an attempt to eliminate false positive results, the diagnostic cut-off level for DCP was increased from 1.5 to 5.0 mu/ml and that of alpha-FP from 20 to 400 ng/ml, the differences between the two markers remained the same. If the two tests were used together, the number of false negative alpha-FP results was reduced from 16.3% to 7.1% and the number of equivocal alpha-FP results was reduced from 11.2% to 5.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversibility of cyclosporin nephrotoxicity after three months' treatment

86 renal allograft recipients were randomly assigned to cyclosporin (Cy) for 90 days followed by azathioprine and prednisolone (Aza and P), or to Aza and P from day 0, as part of the second Oxford trial of short-term Cy use. All 62 patients whose grafts functioned for at least 120 days were included in this study. Serum creatinine was significantly higher in Cy-treated patients than in control patients from day 28 to day 90. Serum uric acid was also significantly higher in Cy-treated patients over the same period. Both creatinine and uric acid fell to the level of the control group after conversion to Aza and P. Serum uric acid was significantly higher for a given level of creatinine during Cy treatment than in either the control patients or the Cy-treated patients after their treatment had been changed to Aza and P. These data imply that Cy affects both the glomerular filtration rate and renal tubular function but that these effects are largely reversible.

Identification of a heparin activated amidolytic enzyme in carp (Cyprinus carpio) plasma

A heparin activated amidolytic enzyme capable of cleaving synthetic thrombin sensitive chromogenic substrates was identified from the plasma of the carp (Cyprinus carpio). Activation was inhibited by KCl, protamine sulphate and human plasma. Heparin was not required for the continued action of the enzyme. Active enzyme was irreversibly inhibited by DFP. The pH and temperature optima was studied and the enzyme semi purified by Sephadex G100 superfine and Sephadex A50 chromatography. An approximate MW of 62,000 was found. Activity generated by as little as 0.002 units of heparin per ml carp plasma was detected. The trivial name carpamidase is proposed for the enzyme.