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)

The effect of Bromelia pinguin extract on the pregnant rat uterus

A non proteinaceous extract of Bromelia pinguin fruit was examined for activity on the rat uterus in vivo and in vitro. The in vivo experiments involved pregnant rats given the extract intraperitoneally. These rats did not abort nor were any foetal deformities observed. The extract inhibited spontaneous activity of the pregnant rat uterus in vitro. The extract of Bromelia pinguin fruit may have some utero-active compound which inhibits uterine motility.(AU)

Effects of interruption of pallidal function on striatal-mediated motor activity: relevance to concepts in neurology and psychiatry

This work was conducted to evaluate the effects of bilateral lesion of the globus pallidus on spontaneous motor behaviour and drug-induced stereotypy. The evidence suggests that the pallidus is necessary for the expression of normal motor behaviour. Bilateral lesioned rats manifested hypoactivity. This hypoactivity or response depression was counteracted by low and high doses of amphetamine. Apomorphime (1.0 mg/kg) induced a normalizing effect on spontaneous motor activity in lesioned rats. However this higher dose of apomorphine induced marked stereotypic activity in lesioned rats. The results of this work raise important implications for certain motor disorders and the psychoses. (AU)

The relationship of the pancreatic part of the common bile duct to the head of the pancreas in Jamaicans - abstract

There is little conformity in the descriptions of the relationship of the common bile duct to the head of the pancreas in textbooks of Anatomy. It has also been suggested that there might be racial differences in the topographical relation of these structures. The pancreatic part of the common bile duct is of primary importance to the biliary surgeon, since it is often necessary to explore it during operations. In view of this it would seem useful to the biliary surgeon in the Caribbean to have basic data on its topographical relations. Duodenum-pancreas specimens of 234 persons of both sexes between the ages of 15 and 97 years were obtained from the postmortem cases in the Department of Pathology, UWI, Jamaica. The common bile duct (CBD) was carefully dissected under the dissecting microscope. The relationship of the CBD to the head of the pancreas could be classified into the following three types: (Type I) the CBD was situated entirely in a groove of the posterior surface of the head of the pancreas and its posterior surface was not covered by pancreatic tissue: 45 cases (19.2 percent); (Type II) The CBD lies in a deep groove, entirely or partially covered on its posterior side by a lingula of pancreatic tissue: 170 cases (72.7 percent) and (Type III) The CBD is surrounded by pancreatic tissue: 19 cases (8.1 percent). It would seem that in about 20 percent of cases (Type I) exploration of the pancreatic part of the CBD would not give problems. However, in the remaining 80 percent (Type II and III) pancreatic tissue was covering this part of the CBD. Although the CBD in Type II (72.7 percent) could easily be reached because of the presence of a cleavage plane filled with loose connective tissue, blood vessels of variable size were overbridging these cleavage planes. Cutting too many of these vessels would interfere with the blood circulation of the pancreatic lobule in that area with the possible consequence of the development of a postoperative pancreatitis. In Type III (8.1 percent of cases) it would be pratically impossible to expose the CBD without disturbing surrounding pancreatic tissue. Comparison with data from the literature revealed that for Type I there was no statistically significant difference, while for Type II and III, respectively there were marked differences. Although factors related to racial differences could have contributed to these differences, differences in the methods of investigation could not be excluded (AU)

Light microscopic and ultrastructural changes of the exocrine pancreas in magnesium deficient rats

In magnesium deficient rats with a clinical picture of protein malnutrition, pancreatic changes typical of protein malnutrition were expected. However, in rats fed for four weeks on a low magnesium diet (protein content 25 percent), light and electron microscopic studies revealed that the ascinar cells of the pancreas were packed with zymogen granules, suggesting a disturbance in the discharge (rather than in the production) of the pancreatic enzymes. The mitochondria and the lumina of the RER were swollen. The nuclei had an irregular outline, the chromatin was aggregated into irregular granules and the nucleolemma of the nucleolus was fibrillar. It was suggested that the disturbance in the release of pancreatic enzymes might cause a maldigestion of the dietary protein, which eventually would lead to the condition of protein malnutrition in the magnesium deficient rats. The disturbance of exocytosis in the pancreas of magnesium deficient rats might be due to the preferential use of all the available magnesium for protein (enzymes) synthesis so that there were no magnesium ions left for the energy dependent discharge of the zymogen granules (AU).

Monosodium glutamate in the chick embryo: lack of obvious toxic or teratogenic effects when administered at 24 hours incubation

The administration of monosodium glutamate (MSC) to chick embryos at 24 hours did neither produce gross developmental defects nor influence growth by 72 hours total incubation. The concentration of MSG administered ranged from 0.3 to 46.6 percent, the volumes injected being 0.05, 0.1, or 0.2 ml. Several injection methods were evaluated. It is suggested that injection into the centre of the yolk is the most effective way to give water-soluble treatments during this period of development (AU).

Review of the aetiology and pathogenesis of acute pancreatitis: Part IV: Auto-immune reactions, neurogenic and miscellaneous factors

It is possible that in many cases, acute pancreatitis may develop because of auto-immune reactions. There are positive indications that neurogenic factors may play an important role in the development of some cases of acute pancreatitis. The problems pertaining to hereditary pancreatitis, the association of pancreatitis with pregnancy, ureamia, certain drugs and the sting of scorpions have been discussed (AU)

A review of the aetiology and pathogenesis of acute pancreatitis: Part III: Nutritional factors and metabolic disorders

Protein deficiency may increase the susceptability of patient to pancreatic damage. It has been suggested that this protein malnutrition may be the important factor in producing pancreatic lesions in chronic alcholics with poor dietary habits. The association of pancreatic tissue is still controversial even though there have been reports of pancreatitis associated with corticosteroid therapy (AU)

A review of the aetiology and pathogenesis of acute pancreatitis Part II: Obstruction with hyper-secretion theory, alcoholism, vascular factors and trauma

Acute pancreatitis is generally accepted as being due to obstruction of the pancreatic duct and hyper-section but the activation of trypsinogen into trypsin is not fully understood. The value of trasylol in pancreatitis is debatable. The roles of alcoholism, circulatory disturbances and trauma in the aetiology of pancreatitis are discussed (AU)

A review of the aetiology and pathogenesis of acute pancreatitis: part 1: Classification, role of infection, common channel theory and duodenal reflux

There are still contradictory opinions concerning the aetiology and pathogenesis of acute pancreatitis. The problem of lymphatic spread of infection from the biliary tract to the pancreas, which in the thirties was considered as improbable, has been re-opened by the results of more recent investigations. The common channel theory which was once considered to be the explanation for most cases of pancreatitis, can account for only a small proportion of cases of pancreatitis. There is still lack of agreement as to the role of duodenal reflux in the causation of pancreatitis (AU)

Pancreatico-biliary duct system in Jamaicans

The anatomy of the pancreatico-biliary duct system in Jamaicans was investigated with the following results: 1. The incidence of the different patterns of union of the cystic and common hepatic ducts showed marked differences from data derived other populations. 2. The cystic and common hepatic ducts may have a common wall. 3. The incidence and course of aberrant bile ducts correspond to those in the literature. 4. The upper limit of normality of the flattened width of the common bile duct is suggested to be 11 mm. 5. The presence or absence of smooth muscle tissue in the common bile duct wall is discussed in relation to: (a) the role of the duct as a passageway of bile, (b) problems encountered when grafting, and (c) causation of biliary pain. 6. In 8.1 percent of cases it was difficult to expose the pancreatic part of the common bile duct because it was surrounded by pancreatic tissue. 7. In 9.4 percent of specimens the pancreatic part of the common bile duct coursed for the whole or part of its lenght alongside the medial wall of the duodenum without pancreatic tissue intervening between them. 8. In 19.3 percent of cases the duct of Santorini was as big as or bigger than the duct of Wirsung, a higher incidence than that reported elsewhere. 9. It appeared that no real sphincter exists at the duodenal end of the duct of Santorini. 10. The incidence of a common channel/ampulla (44.4 percent) was low if compared with the data in the literature. 11. The mucosa folds in the intramural parts of the common bile duct and the duct of Wirsung might play a significant role in the prevention of duodenal reflux and the regulation of the flow of bile and pancreatic secretion into the duodenum. 12. The variability in the component parts of the sphincter of Oddi was investigated. A sphincter choledochus was present in all cases, a common hepatopancreatic sphincter (=sphincter "ampullae") was found in 45.9 percent of cases, but a clearly-defined sphincter pancreaticus was not observed. 13. It is postulated that the presence or absence of a common hepatopancreatic sphincter may be one of the important factors in determining the patency or non-patency of the duct of Santorini at the papilla minor. The clinical and functional implications of these findings are discussed (AU)

Sexual dimorphism in the basilar part of the occipital bone of the dog (canis familiaris)

Sexual dimorphism in the surface markings of the basilar part of the occipital bone of 34 male and 46 female dog's skulls were studied with the following results: 1 of 34 male skulls showed a female type surface marking, 4 of the 46 female skulls showed surface markings of the opposite sex, while 2 of the male and 3 of the female skulls could not be classified as belonging to either type, so that 10 out of the 80 skulls could not be identified correctly, indicating that 87.5 percent of the skulls could be identified positively. Considering that there are hardly any sexual differences in the other surface markings or in the dentition of the dog's skull, these findings may be of some help in sexing the skull of the dog (AU)