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Biomedical subjects

D J Du Plessis

Publications and source records attributed to D J Du Plessis.

At least 19 recordsLinked to original sources
PubMed1997

Does urokinase play a role in renal stone formation?

Renal stone formation is a complex multifactorial disease, and it is believed that the initial step in the pathogenesis of urolithiasis must be the precipitation of an organic matrix of mucoproteins followed by precipitation of minerals onto this matrix. An important factor in this process may be the activity and/or concentration of the urinary enzyme, urokinase, which would affect the level of urinary mucoproteins such as uromucoid. In support of this hypothesis, ELISA studies were conducted to investigate the urokinase concentrations in urine obtained from males (22-60 years) with and without renal stones. These results showed a significant decrease in urinary urokinase concentration of renal stone patients which, once again, underlines the possible involvement of urokinase in renal stone formation. Therefore, it seems logical to conclude that urokinase may play an integral role in this multifactorial disease.

Adult↗
PubMed1994

Can linoleic acid and gamma-linolenic acid be important in cancer treatment?

This hypothesis proposes that the essential fatty acids (EFAs), linoleic acid (LA) and gamma-linolenic acid (GLA), play important roles in cancer treatment. Oxidation of LA by lipoxidase especially increases tumour cell death, whilst GLA inhibits urokinase-type plasminogen activator (uPA) activity. Increased uPA activity is: firstly, responsible for cancer invasion and metastasis and secondly, responsible for proteolysis of lipoxidase which favours a decrease in cancer cell death. Addition of LA and GLA to available therapeutic regimens may be worth considering in cancer treatment.

Antineoplastic Agents, Phytogenic↗
PubMed1992

A novel study on the effect of acetylsalicylic acid on the binding capacity of estrogen receptors from MCF-7 cells.

The effect of acetylsalicylic acid (ASA, aspirin) was investigated on [3H]-estradiol-17 beta ([3H]-E2) binding to estrogen receptors (ER) from MCF-7 mammary tumour cells. No effect was observed using the monoclonal estrogen receptor-enzyme immunoassay (ER-EIA). In contrast to the ER-EIA, the radioreceptor assay (RRA) showed decreases of [3H]-E2 specific binding in the presence of increasing amounts of ASA. It is therefore concluded that these results demonstrate that ASA possibly affects the direct binding of E2 to region E of the ER of human breast cancer MCF-7 cells, but does not affect binding of monoclonal antibodies to regions D and F of the ER.

Antibodies, Monoclonal↗
PubMed1991

Castration plus nilutamide vs castration plus placebo in advanced prostate cancer. A review.

Combination of antiandrogen treatment with surgical or medical castration should improve the efficacy of endocrine treatment of prostatic cancer by blocking the effects of adrenal androgens. A nonsteroidal antiandrogen, nilutamide, has shown promising results in preliminary open studies. In a short-term (29 days) comparison of nilutamide plus buserelin and buserelin plus placebo, nilutamide (300 mg/day), significantly reduced bone pain, and fewer patients experienced worsening pain than in the control group. The initial buserelin-induced increase in prostatic acid phosphatase was prevented by nilutamide, but there was a similar increase in testosterone and gonadotropin concentrations to that seen in the control group. Thus, nilutamide can prevent the tumor flare-up associated with the start of luteinizing hormone-releasing hormone (LH-RH) treatment, even though the endocrine responses are not affected. In three multicenter, randomized, double-blind placebo-controlled trials of castration and nilutamide involving 248 patients, the combination of nilutamide and castration decreased bone pain, improved performance status, and increased the number of patients with objective regression, compared with patients who were castrated but did not receive nilutamide. Nilutamide was generally well tolerated, though visual disorders, gastrointestinal disorders, and alcohol intolerance were reported in patients receiving nilutamide. The results suggest that nilutamide improves the efficacy of castration in patients with prostatic cancer. Current studies are investigating the effects of this treatment on survival and the risk-benefit ratio.

Androgen Antagonists↗
PubMed1991

Quantitative evaluation of the penile vascular status by means of the 99mTc-penogram in conjunction with either papaverine or prostaglandin E1 in the anaesthetised baboon model.

The evaluation of both the arterial blood supply and the venous drainage of the penis is essential in the assessment of the impotent male. The vasoactive drugs papaverine and prostaglandin E1, as intracavernous injections, cause penile erections by influencing arterial blood supply and venous drainage. These drugs were used in a baboon model together with a 99mTc-penogram to provide information on the vascular status of the penis. An increase in penile blood pool was observed, more dramatic and rapid after administration of papaverine. A quantitative assessment of the vascular status seems possible and will next be monitored in a vascular-compromised baboon for purposes of clinical application.

Alprostadil↗
PubMed1988

A progressive radiorenographic (99mTc-DTPA) presentation of surgically induced renal vein hypertension in baboons.

A 99mTc-DTPA radiorenographic study, supported by excretory urography, blood chemistry and eventually histology was performed on 8 chacma baboons (Papio ursinus) after surgical induction of unilateral renal vein hypertension. Frequent sequential repeat renograms during 6 post-operative months detected fluctuating renal behaviour but did not reveal typical course of the disease. Neither did any one of the radiorenographic parameters (TP, T1/2, FF, relative clearances and perfusion) prove to be more sensitive than the others in detecting abnormalities. Initial microscopic or macroscopic haematuria and proteinuria in general eventually cleared up. Light microscopy demonstrated only mild abnormalities. The effects of venous occlusion of the kidney and the prognosis seemed to be variable as was reflected by radiorenography.

Animals↗
PubMed1986

Entrapment of platelets in the penis during and after erection.

Because of the development of hypercoagulability and the deposition of fibrin in the penis during erection a study of the possible role of platelets in this process was undertaken. Platelet response was studied in 9 adult chacma baboons (Papio ursinus) using autologous in vitro indium-111-labelled platelets and sequential scintigraphy of the penis during erection. The blood pooling pattern was obtained using in vivo technetium-99m-labelled red cells in a similar investigation. A statistically significant retention of platelets occurred during and after erection, which could not be attributed to blood pooling (P less than 0,05). Entrapment of platelets could lead to enhanced activity and activation, and might play a significant role in hypercoagulability and fibrin deposition during erection. Therefore platelets could be an important factor in the pathogenesis of ageing impotence.

Animals↗
PubMed1986

[Anomalies of the inferior vena cava. 2 case reports].

Two cases of anomalous inferior vena cava are presented, with the emphasis on embryology. The first patient was investigated by venography for a clinically proven varicocele as a probable cause of infertility. A double inferior vena cava was found during venography, and was confirmed by computed tomography (CT). In the second case a left-sided inferior vena cava was an incidental finding when a CT scan was done as a diagnostic procedure in a case of Hodgkin's disease. A short summary of the embryology and the significance of the variants is presented.

Adult↗
PubMed1985

[The evaluation, classification and management of 300 impotent patients].

Three hundred impotent patients were evaluated by a general and sexual questionnaire, clinical examination, hormonal assay, penile blood pressure measurements, erectiometry, urodynamic studies and ultrasonography of the corpus cavernosum. The patients were classified according to the cause of the impotence; 44% had a psychogenic basis, 13% a neuropathy, 39% a vasculogenic cause and 4% a combination of neuropathy and angiopathy. Psychogenically impotent patients were referred for further treatment. Twenty penile prostheses were implanted in the organic group; 19 patients were satisfied with the result. This diagnostic approach to impotence classification and treatment according to the cause and the careful selection of patients for surgery improved the success rate.

Adult↗
PubMed1982

[Treatment with amoxicillin and clavulanic acid of urinary tract infections in patients with spinal injuries].

Augmentin, a formulation of amoxycillin trihydrate 250 mg and sodium clavulanate 125 mg per tablet (A-CS) (Augmentin; Beecham), was used in treating 29 episodes of urinary tract infection occurring in 26 patients admitted to the Spinal Unit of the H. F. Verwoerd Hospital, Pretoria. Patients who had a urinary bacterial cell count of more than 105 of the same amoxycillin-resistant organism before and after the oral administration of amoxycillin 500 mg 3 times a day for 48 hours, received 2 A-CS 375 mg tablets orally, 3 times a day at the start if a meal for 5 days. The 29 strains of amoxycillin-resistant organisms treated in this study were: Escherichia coli (11), Klebsiella pneumoniae (11), Proteus mirabilis (4), Enterobacter cloacae (2), and Staphylococcus epidermidis (1). The bacteriological success rate 24 hours after therapy was 100% and 8 days after therapy 69%, dependent on patient management. In patients on free drainage and managed with condoms a bacteriological success rate of 55,5% was recorded and in patients managed by intermittent catheterization a bacteriological success rate of 75% was recorded. Side-effects were minimal; 1 patient complained of dizziness and no instances of nausea or vomiting were reported. Haematological, renal and hepatic monitoring before and after A-CS-therapy revealed no drug-related toxicity.

Amoxicillin↗