R. C. Franz

The effect of calcium and magnesium ions on urinary urokinase and sialidase activity

SummaryThe effect of a promoter (calcium) and an inhibitior (magnesium) of urolithiasis was spectrophotometrically studied on urokinase (0.45 IU) and sialidase (5 mM). Although these mineral did not affect the sialidase activity, total inhibition of urokinase activity was observed with either 0.05 M calcium chloride or 0.1 M magnesium chloride. This observation might explain why calcium and magnesium respectively function as a promoter and an inhibitor of stone formation.

Thromboxane B2 Production During Erection

Summary:  The effect of erection on 6‐keto‐PGF1α and thromboxane B2 in penile blood during electrically evoked erection was studied in the chacma baboon. 6‐keto‐PGF1α remained at a low concentration, but thromboxane B2 showed a statistically significant rise 8–10 minutes after commencement of erection. Elevated thromboxane B2 during erection may potentiate platelet aggregation and may be one of the key events in the pathogenesis of ageing impotence.

Ultrastructural changes of platelet aggregates and fibrin networks in a patient with renal clear cell adenocarcinoma: a scanning electron microscopy study.

A 47‐year‐old male patient presented with weight loss, hematuria, and a left renal mass, which proved to be a clear cell renal carcinoma with multiple liver, pulmonary and bone metastases. The platelet count was raised initially (414 × 109/L) but declined 10 weeks after a debulking procedure followed by chemotherapy. Fibrin clots were prepared for scanning electron microscopy (SEM) by adding human thrombin to platelet rich plasma (derived by differential centrifugation of fresh blood samples taken from the patient as well as controls). The clots were washed, fixed in 2.5% glutaraldehyde and Dulbecos phosphate buffered saline and prepared for SEM with a Zeiss Ultra 55 FEG SEM. The SEM photographs revealed an altered morphology of the platelet aggregates with multiple breakages in the platelet membrane, showing a pock‐marked, crenated, prune‐like appearance as opposed to the smooth rounded globular membrane of the controls. The ultrastructural morphology of the fibrin bound platelet aggregates in this patient with renal carcinoma therefore showed a disrupted cytoskeletal architecture which appears to be similar to the apoptotic changes of programmed cell death as described by Bornman et al. (2007) and Pretorius et al. (2008). These features may well be a distinct ultrastructural hematological manifestation of a previously unidentified paraneoplastic syndrome. Microsc. Res. Tech. 2009.

Evaluation of the diagnostic efficacy of autologous 111In-labelled platelets as a scanning agent for deep vein thrombosis in the chacma baboon

The diagnostic efficiency of autologous 111In-labelled platelets (ILP) as a scanning agent in deep vein thrombosis (DVT) was investigated in 24 South African baboons (Papio ursinus). Thrombi were surgically induced by stasis, intimal injury and the injection of thrombin in the common femoral veins of adult baboons. The thrombi were allowed to age for 1, 2, 4, 8, 24, 48 and 72 h before injecting the ILP. Scanning was done with a large field gamma camera at 10 min post injection and again at 2, 4, 6, 8, 10, 14, 24, 48 and 72 h. Time-activity curves were thus obtained and it was possible to establish an optimal time after injection of the ILP to scan for each group of thrombi. The results indicate that only the younger thrombi (1–8 h after thrombus formation) were detected. Twentyfour hour and older thrombi were not visualised. A favourable time to scan in the case of the younger thrombi appeared to be approximately 20 h after the injection of ILP. However, the thrombus age limitation still impairs the diagnostic efficiency of the procedure.