The stock of white rats in the preclinical animal house, University of the West Indies, Mona, can be used as an animal model for development of breast tumours

It is well known that not all strains of laboratory rats are suitable for use as an experimental animal model for tumour development; hence, in every article published, the strain of rats used in the research is always accurately stated. Before 1984, the stock in the Mona-Preclinical Animal House comprised Wistar rats. These rats were susceptible to the development of breast tumours. The present Mona stock of rats is the product of an inbreeding between the old Wistar and Sprague-Dawley rats, the later introduced into the colony in 1984 by the Biochemistry Department for experimental purposes. After the experiments were completed, these rats were used for interbreeding with the Wistar rats. In 1999, experiments were started to develop breast tumours in the female rats of this mixed breed. A carcinogen (DMBA) was administered intragastrically into 14 females rats and after 10 months of observations, 13 (93 percent) developed tumours, while in the same period no tumours were found in the controls (13 female rats). Therefore, it can be stated that the present stock of rats is still suitable as an animal model for the development of breast tumours. Experiments to develop prostatic cancer in the male rats are in progress. It is suggested that authors of articles reporting the results of research using the Mona colony of rats should clearly state that the "Mona strain' of white rats used. To further establish this Mona strain, improved maintenance and breeding methods should be implemented and also collection of basic data such as average litter size, birth weight, growth curve and incidence of the development of spontaneous tumours should be stated.(Au)

The embryocidal effect of Zinc (Zn) and Cadmium (Cd) in pregnant Mona strain rats

OBJECTIVE: To investigate the toxicity of zinc and cadmium on pregnant Mona strain rats. METHODS: A total of 21 female rats, divided into 3 groups of 7 rats each, were mated, and on the 8th day of gestation, these pregnant rates were injected subcutaneoulsly with 3 mg/kg Zinc sulphate, Group 1:3 mg/kg Cadmium sulphate, Group II, and normal saline, Group III. Animals were fed purina lab chow and given water ad libitum. On the 15th day, animals were sacrified with ether, the uteri were removed and examined. Observations on embryocidal effects and foetal abnormalities were recorded. RESULTS: Zinc at a dose of 3 mg/kg administered subcutaneously on the 8th day of gestation had a marked embryocidal effect (13.8 percent). This was observed to a much lesser degree (1.5 percent) with Cd treatment. CONCLUSION: The results demonstrate the need for further research and a degree of caution in recommending the liberal use of zinc as a dietray supplement (especially in pregnancy). Further detailed analysis of the degree of air pollution and the vegetable material grown in areas with high concentrations of heavy metals is recommended.(Au)

Ascaris lumbricoides in the paranasal sinuses of a Jamaican adult

While preparing a routine sagittal section of the human head and neck for the teaching of anatomy, 3 mature Ascaris lumbricoides worms were seen in the maxillary sinus and 3 in the sphenoidal sinus. Of the worms in the maxillary sinus, 2 were males and one was female, while in the sphenoidal sinus all 3 worms were females. The worms measured 7 - 11 cm in length Light microscope examination of the maxillary sinus wall revealed a few eggs of the parasite in close relation to the epithelium. The migratory abilities of A. Lumbricoides adult worms are well documented and most often involve the bile and pancreatic ducts (Asrat & Rogers, 1995). In a endemic area of Kashmir, India, A. Lumbricoides was the cause of acute pancreatis in 23 percent of 256 patients (Khuroo et al., 1992). Worm extraction and biliary drainage were indicated in 32 percent of 156 patients who had acute hepatobiliary and pancreatic ascariasis, and this resulted in rapid relief of symptoms in most patients (Khuroo et al., 1993). In the case represented, the ostia of the sinuses were between 3 and 4 mm in width and were therefore large enough for the passage of the worms as adults. We are not aware of any other report of ectopic ascariasis involving the sinuses. Clinical data on the current case were not available to us. A. Lumbricoides has high fecundity and the fact that only a few eggs were seen in the sinuses suggests that the worms were immature or that there was a reduction in egg production due to overcrowding or lack of adequate nutrition.(AU)

Effect of Aqueous neem (azadirachta indica) extract on testosterone and other blood constituents in male rats: a pilot study

Effect of oral administration of crude aqueous neem extract on serum testosterone and other blood constituents was studied in the male Wistar rats for 10 weeks. The neem treatment resulted in significant decreases (p,0.01) in total testosterone, total bilirubin and K+ in serum. There were also increases (p<0.05) in packed cell volume, mean corpuscular haemoglobin concentration, red blood cell, white blood cell and lymphocyte counts without showing any cytotoxic effects in the body (AU)