A new model of congestive heart failure in the mouse due to chronic volume overload.

OBJECTIVE: Recently, deletion of specific genes by so called knock-out techniques has become important for investigating the pathogenesis of various diseases. This form of genetic engineering is widely performed in murine models. There are, however, only a limited number of mouse models available in cardiovascular pathology. The objective of this study, therefore, was to develop a new model of overt congestive heart failure associated with myocardial hypertrophy in the mouse. METHODS: Female C57/BL6 mice weighing 19-20 g were anesthetized with ether. After abdominal incision, the aorta was temporarily clamped proximal to the renal arteries. The aorta was then punctured with a needle (outer diameter 0.6 mm) and the needle was further advanced into the adjacent vena cava. After withdrawal of the needle, the aortic puncture site was sealed with cyanoacrylate glue. The clamp was removed, and the patency of the shunt was visually verified as swelling and mixing of venous and arterial blood in the vena cava. Sham-operated mice served as controls. RESULTS: Perioperative mortality of mice with aortocaval shunt was 42%. Four weeks after shunt induction, mice showed a significant cardiac hypertrophy with a relative heart weight of 7.5+/-0.2 mg/100 g body weight (vs. 5.1+/-0.7 mg/100 g in control mice, P<0.001). While no changes in blood pressure and heart rate occurred, left ventricular enddiastolic pressure was significantly increased in mice with shunt, and left ventricular contractility was impaired from 6331+/-412 to 4170+/-296 mmHg/s (P<0.05). Plasma concentrations of atrial natriuretic peptide (ANP) and its second messenger cGMP as humoral markers of heart failure as well as ventricular expression of ANP- and brain natriuretic peptide (BNP)-mRNA were significantly increased in mice with shunt compared to control mice. CONCLUSIONS: The aortocaval shunt in the mouse constitutes a new model of overt congestive heart failure with impaired hemodynamic parameters and may be a useful tool to investigate the role of particular genes in the development of heart failure.

The effects of B-sitosterol (BSS) and B-sitosterol glucoside (BSSG) mixture on selected immune parameters of marathon runners: inhibition of post marathon immune suppression and inflammation.

A pilot study was undertaken to investigate the effects of the intake of capsules containing the plant sterols and sterolins (BSS:BSSG mixture) on selected immune parameters of volunteers participating in an ultra-marathon in Cape Town, South Africa. Those runners having received active capsules (n=9) showed less neutrophilia, lymphopenia and leukocytosis when compared to their counterparts having received placebo capsules (n=8): the placebo treated individuals showed significant increases in their total white blood cell numbers as well as in their neutrophils (p=0.03 and 0.03 respectively). Furthermore, statistically significant increases within lymphocyte subsets were observed in the runners having received the active capsules: CD3+ cells increased (p=0.02) as did CD4+ cells (p=0.03). In parallel, the BSS:BSSG capsules decreased the plasma level of IL6 in the runners using the active capsules (p=0.08) and significantly decreased the cortisol: DHEAs ratio (p=0.03), suggesting that these volunteers had less of an inflammatory response and were less immune suppressed during the post-marathon recovery period. These findings justify further investigations into the use of the phytosterols to prevent the subtle immunosuppression associated with excessive physical stress.

Primary liver cancer in two sisters in Holland with intermittent acute porphyria.

Two sisters living in Holland, with a niece now living in South Africa, were reported in 1958 to have inherited intermittent acute porphyria (IAP). In 1994 both sisters died from primary liver cancer. Other reports have also noted an increased mortality from carcinoma of the liver in porphyrics. Porphyria variegata has a high prevalence in white and coloured South Africans, and it would be relatively easy to ascertain whether those who have inherited the gene for this disorder, in South Africa, have a higher than reported mortality from liver cancer. If they do, consideration should be given to ways to reduce their risk of developing and dying from this cancer.

A randomised placebo-controlled trial of the efficacy of beta-sitosterol and its glucoside as adjuvants in the treatment of pulmonary tuberculosis.

OBJECTIVE: To evaluate the adjuvant effect of beta-sitosterol and its glucoside in the treatment of culture proven pulmonary tuberculosis (PTB). DESIGN: A blinded randomised placebo-controlled trial in culture proven drug sensitive PTB. Patients were hospitalised for the duration of treatment and evaluated at monthly intervals with regard to sputum culture positivity, chest radiography, weight gain, Mantoux test response, routine haematology and liver functions. STATISTICAL EVALUATION: General linear models for repeated measures (SAS GLM package) compared the interaction effects, group effects and time effects of findings in 19 patients receiving sitosterols with those in 18 patients receiving a placebo (talcum powder). Absolute values and change from baseline values were evaluated, although only the latter are reported. RESULTS: Weight gain was significantly greater in the sitosterol group (mean weight gain 8.9 kg) than the placebo group (mean gain 6.1 kg) (P = 0.0023 group effects; P = 0.0001 for time effects). Speed of achieving culture negativity, radiological improvement and induration on Mantoux testing was similar in the two groups. Change in lymphocyte counts from baseline was significantly higher in the sitosterol group (P = 0.0001 and P = 0.0001 for group and time effects) as was the increase in eosinophil counts (P = 0.0001 and P = 0.0137 for group and time effects). CONCLUSION: The study has shown significantly improved weight gain and higher lymphocyte and eosinophil counts in PTB patients receiving sitosterols in addition to an efficacious antituberculosis regimen. Sitosterols and their possible mode of action should now be evaluated in larger numbers of tuberculosis patients and in diseases with a similar immunopathogenesis.

The pharmacokinetic behaviour of hypoxoside taken orally by patients with lung cancer in a phase I trial.

OBJECTIVE: To study the pharmacokinetic behaviour of hypoxoside taken orally by 24 patients with lung cancer. DESIGN: Randomised open study with three single doses of 1,600, 2,400 and 3,200 mg standardised Hypoxis plant extract (200 mg capsules) and a multiple-dose study on the first 6 patients taking 4 capsules 3 times daily for 11 days. PARTICIPANTS AND SETTING: Patients with histologically proven squamous, large-cell or adenocarcinoma were hospitalised at the Radiation Oncology Ward, Karl Bremer Hospital, Bellville, W. Cape. METHODS: Blood was drawn at regular intervals up to 75 hours after single doses and the concentrations of metabolites of the aglucone of hypoxoside, rooperol, were measured with a high-performance liquid chromatography method. For the multiple-dose study blood was drawn before the first dose each day. Concentration-time relationships were analysed according to a conventional single open-compartment model and also by using the NONMEM digital computer programme. RESULTS: Neither hypoxoside nor rooperol appear in circulation. This is due to complete phase II biotransformation to diglucuronide, disulphate and mixed glucuronide-sulphate metabolites, of which the latter is the major component. Considerable interpatient variation in concentration-time relationships was found in the single-dose studies. It was due to an active enterohepatic recirculation in some patients and a distinct lag phase in others together with zero-order rate of formation of rooperol in the colon. Computer modelling indicated a single open-compartment model in which the mass of the patient did not influence volume of distribution and clearance because formation of the metabolites is dependent on the metabolising capacity of the patient. However, the elimination of the metabolites follows first-order kinetics with half-lives ranging from 50 hours for the major metabolite to 20 hours for the two minor metabolites. Multiple-dose studies also showed large interpatient variation. CONCLUSION: In order to reach metabolite levels near 100 micrograms/ml, which have been shown to be tumouricidal after enzymatic deconjugation to rooperol, maintenance doses need to be individualised for each patient. For most patients, however, a daily dose of 2,400 mg was sufficient.

A phase I trial of hypoxoside as an oral prodrug for cancer therapy--absence of toxicity.

OBJECTIVE: To assess the toxicity of hypoxoside taken orally by 24 patients with lung cancer. DESIGN: Open study with patients taking 1,200-3,200 mg standardised Hypoxis plant extract (200 mg capsules) per day divided in 3 doses in order to maintain metabolite blood levels near 100 micrograms/ml. PARTICIPANTS AND SETTING: Patients with histologically proven squamous, large-cell or adenocarcinoma were hospitalised initially at the radiation oncology ward, Karl Bremer Hospital, Bellville, W. Cape. Thereafter they returned every 2 weeks for full clinical examinations. METHODS: Routine biochemical and haematological measurements were done. Patients underwent regular full clinical examinations including radiographs and computed tomography scanning according to the discretion of the principal investigator. RESULTS: Nineteen patients on hypoxoside therapy survived for an average of 4 months with progression of their primary tumours and metastases, while 5 survived for more than a year. One of them survived for 5 years and histological examination of the primary lesion showed absence of cancer. No toxic effects, in clinical examinations or biochemical or haematological measurements, were found that could be ascribed to the ingestion of hypoxoside. Only one occasion of possible drug intolerance, with anxiety, nausea, vomiting and diarrhoea, was noted. CONCLUSION: The absence of toxicity warrants further investigation of hypoxoside as an oral prodrug, especially in patients with slow-growing necrotising tumours that are inoperable and have high concentrations of beta-glucuronidase and sulphatase as well as a high sensitivity for rooperol.