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BACKGROUND: A decoction comprised of Nigella sativa seeds, Hemidesmus indicus root bark and Smilax glabra rhizome is being recommended for cancer patients by a family of traditional medical practitioners of Sri Lanka. Previous investigations have demonstrated that a short term (10 weeks) treatment with the decoction can significantly inhibit diethylnitrosamine (DEN) mediated expression of Glutathione S-transferase P form (GST-P) in rat liver. The objective of the present investigation was to determine whether long term (16 months) treatment with the decoction would be successful in inhibiting in rat livers, not only DEN- mediated expression of GST-P, but also the carcinogen mediated development of overt tumours (OT) or histopathological changes leading to tumour development (HT). METHODS: Thirty-six male Wistar rats were divided into 3 groups of 12 each. Groups 1 and 2 were injected intraperitoneally (i.p) with DEN (200 mg/kg) while group 3 was injected normal saline (NS). Twenty-four hours later, decoction (DC; 6 g/kg body weight/day) was orally administered to group 1 rats, while groups 2 and 3 (DEN-control and normal control) were given distilled water (DW). Treatment with DC or DW continued for 16 months. At the end of the 9th month and 16th months (study 1 and study 2 respectively), six rats from each group were sacrificed, and livers observed for OT or HT, both visually and by subjecting liver sections to staining with Haemotoxylin and Eosin (H & E), Sweet's Silver stain (for reticulin fibers), Periodic Acid Schiff (PAS) staining (for glycogen), and immunohistochemical staining (for GST-P). RESULTS: At the end of 9 months (study 1) a hepatocellular adenoma (HA) developed in one of the rats in the DEN + DW treated group (group 2). At the end of 16 months (study 2), livers of all rats of group 2 developed OT and HT. Large areas of GST-P positive foci were also observed. No OT, HT or GST-P positive foci were detected in any of the other groups. CONCLUSION: Protection against DEN-mediated carcinogenic changes in rat liver can be achieved by long term treatment with the DC comprised of N. sativa seeds, S. glabra rhizome and H. indicus root bark.

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The neurotoxic effect of palmyrah (Borassus flabellifer L.) shoot flour on Wistar rats has been reported previously by Arseculeratne and co-workers. A deficiency in previous studies was an inadequate description of the methodology, especially on the composition and consumption of test and control feed, and weight gain/losses. This study shows that feeds containing 100% and 70% palmyrah flour result in very little or no feed consumption, and deaths reported could have been interpreted as being due to starvation. A mixture of 50% palmyrah flour and 50% standard breeding feed results in the neurotoxic symptoms such as muscle in-coordination, spasms and immobility of hind limbs reported previously (Arseculeratne and coworkers). These neurotoxic symptoms can be eliminated by heating the palmyrah flour at 80 degrees C for 45 min; that is, detoxification. Attempts were made to reproduce the neurotoxic effect by administering two-fold palmyrah flour extractive compared with that contained in the same flour consumed by experimental rats per day. This did not produce a neurotoxic effects (as reported previously while using rats fed on standard breeding feed). It is interpreted that the nutritional status of the diet influences that manifestation of the neurotoxic effect; the effect being suppressed with a nutritious diet. Studies on the blood enzyme levels of rats showed that while alanine aminotransferase was not affected, aspartate aminotransferase was significantly affected by oral administration of organic solvent-free water and methanol:water (1:1) extractives (P = 0.023 and P = 0.0044), respectively. This study shows that while the reported hepatotoxin is not extracted by these solvent systems, there appears to be a tissue non-specific cellular damage reflected at a subclinical level.

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Ipomoea aquatica Forsk is a common green leafy vegetable consumed in many parts of the world. The present study was designed to investigate the oral hypoglycaemic activity of Ipomea aquatica in streptozotocin induced diabetic Wistar rats, and Type II diabetic patients. Experimental diabetes was induced with streptozotocin in Wistar rats. The rats were then divided into test and control groups. In addition to the standard feed given to both groups the test was fed with the shredded leaves of Ipomoea aquatica (3.4 g/kg) for one week. Type II diabetic patients were subjected to a glucose challenge before and after a single dose of blended I. aquatica. Patients acted as their own controls. The results revealed that consumption of the shredded, fresh, edible portion of I. aquatica for one week, effectively reduced the fasting blood sugar level of streptozotocin-induced diabetic rats (p = 0.01). When subjected to a glucose challenge, the Type II diabetic subjects showed a significant reduction (p = 0.001) in the serum glucose concentration 2 h after the glucose load. However, it was not significantly reduced at 1 h (p < 0.09) post glucose load. There was a 29.4% decrease in the serum glucose concentration of the diabetic patients when treated with the plant extract.

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This study was undertaken to compare the oral hypoglycaemic activity of an aqueous extract of the green leafy vegetable Ipomoea aquatica (dose equivalent to 3.3 g starting material /kg body weight) with that of the known oral hypoglycaemic drug tolbutamide (15 mg/kg body weight) in glucose challenged Wistar rats (3 g/kg body weight, administered 30 min after the administration of Ipomoea aquatica or tolbutamide). One and half hours after administration of glucose (equivalent to 2 h after administration of plant extract or tolbutamide), the mean blood glucose level of the Ipomoea aquatica treated group was 47.5% lower than that of the control group treated with distilled water. The tolbutamide treated group showed a mean blood glucose level which was only 33.8% lower than that of the control group. However, statistical analysis indicated that the blood glucose levels of the Ipomoea aquatica treated group were not significantly different from that of the tolbutamide treated group. Our results show that the aqueous extract of Ipomoea aquatica is as effectve as tolbutamide in reducing the blood glucose levels of glucose-challenged Wistar rats.

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The effects of garlic on diethylnitrosoamine (DEN)-induced hepatocarcinogenesis were examined in male Wistar rats using the medium term bioassay system of Ito based on the two-step model of hepatocarcinogenesis. Carcinogenic potential was scored by comparing the number and area/cm(2) of induced glutathione S-transferase placental form (GST-P) positive foci in the liver with those of the corresponding group (control) of rats given diethylnitrosoamine alone. Treatment with garlic (therapeutic dose 20 mg/kg body wt/day) reduced significantly the number (50% reduction, p < 0.003) and area (48% reduction, p < 0.0007) of GST-P positive foci compared with the control group of animals receiving distilled water. Histopathological examination of rat livers using H & E staining indicated that there was no significant difference between the control group and the garlic treated group in the two pathological parameters namely granularity and vacuolation of the cytoplasm. Our results provide strong supportive evidence for the anticarcinogenic activity of garlic.

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Ipomoea aquatica is a commonly consumed green leafy vegetable in Sri Lanka which is supposed to possess an insulin-like activity [Jayaweera, D.M.A., 1982. Medicinal Plants (Indigenous and Exotic) Used in Ceylon. Part 11. National Science Council, Colombo, Sri Lanka, pp. 99]. Only a little attention has been paid to the therapeutic use of this plant. We studied the oral hypoglycaemic activity of single and multiple doses of I. aquatica in healthy, male Wistar rats after a glucose challenge. There was a significant reduction in the serum glucose concentrations with both single (33%, P<0.0027) and multiple (25%, P<0.02) doses. The optimum dose was 3.4 g/kg while the optimum activity was given 2 h after the administration of the extract. The present study indicates that a boiled, whole extract of I. aquatica exerts an oral hypoglycaemic effect in healthy, male, Wistar rats after a glucose challenge.

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The reliability of self-reported sexual behavior is a question of utmost importance to human immunodeficiency virus (HIV) prevention research. The Timeline Follow-Back (TLFB) interview, which was developed to assess alcohol consumption on the event level, incorporates recall-enhancing techniques that result in reliable information. In this study, the TLFB interview was adapted to assess HIV-related sexual behaviors and their antecedents, and its reliability was assessed. The interview was administered to 110 participants (46% women, M age = 19.7; range = 18-41), and 58 participants who reported sexual behavior during the previous three months returned one week later for a second interview. Test-retest intraclass correlations (rho) from the TLFB protocol showed that all sexual behaviors were reported reliably (rho range = .86 to .97, median = .96). Bootstrapping, a nonparametric statistical technique, was used for significance testing in the reliability analyses. Reliability was equivalent across each of the three months assessed with the TLFB and was equivalent to conventional assessment methods (i.e. single-item questions). These findings show that the TLFB sexual behavior interview provides reliable reports of sexual behavior over three months and yields event-level data that are extremely valuable for sexual behavior and HIV-prevention research.

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