Effect of (+/-)-, (+)- and (-)-gossypol on the lactate dehydrogenase-X activity of rat testis

The effect of (+/-)-, (+)- and (-)-gossypol on testicular lactate dehydrogenase-X (LDH-X) was studied in vitro and in vivo. It was found that racemic gossypol and the two optical enantiomers had similar inhibitory effects on rat testicular LDH-X in vitro. However, neither racemic gossypol nor the enantiomers exhibited an inhibitory effect on testicular LDH-X in vivo. It is concluded that inhibition of testicular LDH-X is not likely to be the mechanism of the antifertility action of gossypol. The inhibition of testicular LDH-X in vitro by all three preparations of gossypol is probably non-specific.     

Comparison of iodine-123 low-density lipoprotein (LDL) and indium-111 LDL binding to mononuclear cells of healthy normolipaemic controls and patients with heterozygous familial hypercholesterolaemia

The binding of radiolabelled lipoproteins, iodine-123-labelled low-density. lipoprotein (LDL) and indium-111-labelled LDL, to peripheral blood mononuclear cells (MNCs) was compared in normolipaemic subjects and in patients with heterozygous familial hypercholesterolaemia (FH). ¹²³I-LDL and ¹¹¹In-LDL binding to MNCs exhibited high-affinity, highly specific, time- and temperature-dependent binding reaching saturation at concentrations above 50 nM. The number of LDL binding sites (B_max) was significantly (P<0.01) lower in FH patients (P<0.001; ¹²³I-LDL: B_max 279±44 ng protein/10⁸MNCs; ¹¹¹In-LDL: B_max 309±43 ng protein/10⁸MNCs) as compared with controls (¹²³I-LDL: B_max 2874±246 ng protein/10⁸ MNCs; ¹¹¹In-LDL: B_max 3145±339 ng protein/10⁸ MNCs). The corresponding dissociation constants (K _d) were 16±8 nM for ¹²³I-LDL and 12±6 nM for ¹²³In-LDL in healthy volunteers (¹²³In-LDL vs ¹¹¹In-LDL, P<0.05). In FH patients, the K _d values were 20±8 nM for ¹²³I-LDL and 16±6 nM for ¹²³In-LDL (P<0.05 vs controls for both ¹²³I-LDL and ¹¹¹In-LDL). ¹¹¹In-LDL binding to MNCs was inhibited (IC₅₀) by 30±8 nM in healthy controls and 38±12 nM in FH patients (P<0.05). ¹²³In-LDL binding to MNCs was inhibited (IC₅₀) by 34±8 nM in healthy controls and 46±10 nM in FH patients (P<0.05). Taken together, these results suggest a reduced number of LDL receptors expressed on MNCs from FH patients. We conclude that ¹¹¹In-LDL and ¹²³I-LDL are equally well suited as a probe of receptor-mediated binding and uptake of LDL.     

Teenagers seeking condoms at family planning services. Part II. A provider's perspective.

This study assessed the ability and preparedness of staff at family planning clinics in Durban to assist in AIDS prevention by promoting condom use among teenagers. Staff at 12 randomly selected clinics were interviewed to assess their attitudes towards teenagers seeking condoms, the information imparted on AIDS and condom use, constraints faced in delivering services, and their perceived role in controlling the spread of AIDS. Despite their awareness of AIDS, those interviewed perceived their role to be that of promoting contraception. Condoms were perceived as a poor choice of contraceptive and their use was discouraged. The pamphlets dispensed along with condoms were thought to provide adequate information about condom use. Information on AIDS was given only if the clinic attender initiated discussion on the subject. Most of the clinic staff were keen to discuss other issues during their consultations, but felt constrained by the large numbers of people they had to attend to and the lack of adequate facilities. If family planning services are to play a role in controlling the spread of AIDS, the first step must be to make this function part of the overall policy. For there to be effective counselling on AIDS prevention, in-service training of current staff is required, as well as more staff and improvements in facilities to ensure greater privacy.     

Effect of photodynamic therapy on blood flow in normal and tumor vessels

The aim of this series of experiments was to determine the dynamic blood flow changes that occur in normal and neoplastic tissues during photodynamic therapy. Mice bearing SMT-F tumors and rats with transplanted chondrosarcomas were injected with graded doses of dihematoporphyrin ether. Studies of changes in single-vessel and whole-tumor blood flow were carried out with 630 nm light activation. A helium neon laser Doppler velocimeter was used to stimulate dihematoporphyrin ether, as well as to measure changes in flow velocity in both single-vessel and whole-tumor models. There was a reduction of flow velocity in all vessels and tumors in animals injected with 1 to 40 mg/kg dihematoporphyrin ether intraperitoneally. The extent of flow reduction was related to drug dose administered. Decreases in blood flow began within 10 seconds of light stimulation and were maximal within 5 minutes. Both normal and tumor vessels responded similarly. We conclude that photodynamic therapy leads to significant microcirculatory changes that may be pertinent to the mechanism of tumor necrosis.     

Interactive image-guided management of colloid cysts of the third ventricle.

OBJECT: Image guidance provides a three-dimensional view of the lesion and allows the surgeon to plan a surgical strategy that takes the relationship of the lesion and the surrounding brain into account. We evaluated the degree of resection and the functional outcome of patients with colloid cysts from the third ventricle submitted to surgical resection using interactive image-guided approach. METHOD: Using image-guided methodology and an endoscopic approach we analyzed the functional outcome of 11 patients with diagnosis of colloid cyst of the third ventricle who were treated at our institution from August 1993 to September 2000. The mean age was 39.5 years and the mean follow-up was 36.5 months. Analyzing the clinical outcome, 54.5% of the patients developed short-term memory disturbance in the first 30 days after surgery. None of these patients persisted with this symptomatology for more than one month. In terms of late post-operative morbidity, 1 patient developed persistent post-operative seizures, which were controlled with anti-seizure medications. Complete resection of the cyst was achieved in all patients. CONCLUSIONS: The low rate of complications and high rate of total resection encourage us to continue using the multimodal technique. Longer follow-up and an increase in the number of patients are needed to assess the efficacy of this methodology.