Central depressant and nootropic effects of daytime melatonin in mice.

BACKGROUND: Effects of orally administered daytime melatonin on novelty induced behaviors and spatial working memory in mice were evaluated using the open field, the Y maze and the radial arm maze. PURPOSE: To ascertain the possible nootropic and/or central excitatory or inhibitory effects of daytime oral melatonin in mice. METHODS: Adult male mice from our colony, assigned to three and four groups for open field tests and memory tests respectively were given vehicle (normal saline), a standard drug Scopolamine at 0.5 mg/kg i.p, single dose, 30 minutes before behavioral study) or one of two doses of melatonin (5 and 10 mg/kg daily for a period of 30 days). All administrations were done between 8.00 a.m. and 9.00 a.m. daily. Behavioral tests were carried out on day 30 after administration. Results were analysed using a one-way ANOVA followed by a posthoc test (Student-Newman-Keul's) and expressed as mean ± S.E.M. RESULTS: Open field tests revealed a significant reduction in rearing and grooming behaviors at both doses tested while no significant changes in horizontal locomotion were seen. Y maze studies showed an improvement in spatial memory in mice that received 5 mg/kg of melatonin when compared to scopolamine control. At 10 mg/kg, no significant improvement was seen. A significant increase in the radial arm maze spatial working memory following melatonin administration was seen at 5 mg/kg and 10 mg/kg compared to scopolamine control. Radial arm maze exploration was also significantly reduced. CONCLUSION: The study demonstrates the ability of exogenously administered melatonin, to affect both central excitation and spatial working memory in mice even when given orally.

Correlates of physicians' attitudes toward communication with HIV/AIDS patients in Ile-Ife, Nigeria.

OBJECTIVES: The study assessed physicians' perceptions of HIV/AIDS patients and identified the determinants of physicians' attitudes toward communication with HIV/AIDS patients in Ile-Ife, Nigeria. METHODS: A semi-structured questionnaire was used to elicit information from 110 physicians in a cross-sectional survey, while in-depth interviews were conducted with 10 people living with HIV/AIDS (PLWHA) who had been previously admitted under the care of the physicians. Univariate, bivariate and multivariate analyzes were conducted. RESULTS: Although most physicians perceived PLWHA positively and 58% of them displayed a positive attitude toward communication with PLWHA under their care, the expectations of the patients concerning HIV/AIDS communication were not being met. Only 43% of physicians expressed any degree of comfort engaging PLWHA in lengthy discussions or communicating the diagnosis of HIV to patients. The strongest correlates of physicians' positive attitude were previous exposure to HIV/AIDS counseling, the number of HIV/AIDS patients treated per month, the number of years spent in the care of PLWHA, and the gender of the physicians (p < 0.05). CONCLUSIONS: Physicians in Ile-Ife, Nigeria are not adequately equipped by way of training to effectively meet the expectations of their patients concerning HIV/AIDS communication. The large number of PLWHA in the country calls for urgent attention to address this important aspect of care.

Vitamin A status of pre-school children in Ibadan (South West Nigeria), risk factors and comparison of methods of diagnosis.

Vitamin A deficiency (VAD) and protein energy malnutrition (PEM), sharing common aetiological factors, are important public health problems in many developing, countries. A cross-sectional survey of the vitamin A status of 128 well nourished and 230 malnourished pre-school children was carried out in order to define factors associated with increased risks of VAD and also to determine the predictive values of CIC-T in identifying serum retinol of < 10 microg/dl in these children. The proportional morbidity rates of VAD defined by serum retinol concentrations (7.3%) and CIC-T (6.2%) was similar (p>0.05), and children aged < 3 years accounted for 70% of VAD cases. VAD occurred in 6.3% and 7.8% of well-nourished and malnourished children respectively. The risk of VAD was increased following measles, history of persistent diarrhoea and wasting. The predictive value of CIC-T is highly dependent on CIC-T such that abnormal and normal smears classification appears to be very robust and predictive of serum retinol of < 10 microg/dl, with sensitivity of 83.3% (95%CI: 61.8-94.5), and specificity of 73.3% (95%CI: 68.3-78.5). Judging by the proportional morbidity rate in this study, VAD appears to be a significant public health problem in both malnourished and well-nourished Nigerian children, especially in children < 3 years of age. The history of measles and persistent diarrhoea appear to increase the risk of VAD. The simplicity, sensitivity and specificity of CIC-T suggest that this procedure is a good screening tool for epidemiological survey of vitamin A status.

Estrogen-nucleic acid adducts: dissection of the reaction of 3, 4-estrone quinone and its radical anion and radical cation with deoxynucleosides and DNA.

Previous studies from our laboratory have shown that 3,4-estrone quinone (3,4-EQ) can redox-cycle and is capable of inducing single-strand DNA breaks in MCF-7 breast cancer cells, as well as reacting with various deoxynucleosides to give several estrogen-nucleic acid adducts. While reactions of 3,4-EQ with all the deoxynucleosides under acidic conditions gave only the N7-Gua adduct, which could proceed by Michael addition, reactions of 3,4-EQ under reductive conditions gave several adducts, including the N7-Gua, C8-Ade, C8-Gua, N3-Thy, and N4-Cyt adducts, suggesting the involvement of a 3,4-EQ radical species. The question as to which of the reactive species, the estrogen quinone or the estrogen semiquinone, that is responsible for estrogen's genotoxic activity has been the subject of recent investigations in several laboratories. To explore this in more detail, we carried out studies on the reactivity of 3,4-EQ, the 3,4-EQ radical anion, and the 3, 4-EQ radical cation with both deoxynucleosides and calf thymus DNA under different pH conditions. Both stable and unstable adducts with guanine and thymine were observed from reactions with DNA. Although adduct levels were somewhat different, the adduct profiles obtained from reactions of 3,4-EQ and its radical anion with both DNA and deoxynucleosides were quite similar and were found to be significantly different from product profiles obtained from reactions with the 3,4-EQ radical cation. Studies conducted with the human breast tumor cell line MCF-7 demonstrated the formation of the N7- and C8-Gua adducts in which the profiles were similar to those obtained from reactions of 3,4-EQ with DNA. These results suggest that the reactive species that is responsible for adduct formation under physiological conditions is most likely to be the 3,4-EQ radical anion.

Estrogen-nucleic acid adducts: reaction of 3,4-estrone-o-quinone radical anion with deoxyribonucleosides.

Metabolic activation of estradiol leading to the formation of catechol estrogens is believed to be a prerequisite for its genotoxic effects. Previous studies have shown that 3,4-estronequinone (3,4-EQ) can redox-cycle and is capable of inducing exclusively single-strand DNA breaks in MCF-7 breast cancer cells [Nutter et al. (1991) J. Biol. Chem. 226, 16380-16386]. These studies, however, could not provide conclusive evidence about the mechanism of estrogen carcinogenesis. In order to explore this in more detail, we have shown previously that 3,4-EQ can react with adenine under electrochemical reductive conditions to yield an estrogen-nucleic acid adduct [Abul-Hajj et al. (1995) J. Am. Chem. Soc. 117, 6144-6145]. In this paper, we report the synthesis and identification of nine estrogen-nucleic acid adducts obtained from reaction of 3,4-EQ with deoxycytidine, deoxythymidine, deoxyadenosine, and deoxyguanosine. Purification of reaction mixtures using HPLC gave sufficient quantities of reaction products for identification using 1H-NMR and mass spectral determinations. Reaction of 3,4-EQ with dCyd, dThd, dAdo, and dGuo gave the following estrogen-nucleic acid adducts: N4-(4-hydroxyestron-1-yl)deoxycytidine, N4-(4-hydroxyestron-2-yl)deoxycytidine, N3-(4-hydroxyestron-1-yl)thymine, N3-(4-hydroxyestron-1-yl)deoxythymidine, N6-(4-hydroxyestron-1-yl)deoxyadenosine, 8-(4-hydroxyestron-1-yl)adenine, N2-(4-hydroxyestron-1-yl)deoxyguanosine, 8-(4-hydroxyestron-1-yl)guanine, and 8-(4-hydroxyestron-2-yl)guanine. Adduction through the NH2 group of dAdo, dGuo, and dCyd results in formation of chemically stable adducts. On the other hand, adduction at C-8 led to the formation of several depurination adducts identified as 4-OHE1-1-C8-Gua, 4-OHE1-2-C8-Gua, and 4-OHE1-1-C8-Ade.

Potent growth inhibitory activity of zidovudine on cultured human breast cancer cells and rat mammary tumors.

Originally designed as an antitumor agent, zidovudine (AZT) has exhibited only marginal tumor growth inhibitory activity. Recently, three abstracts have described positive clinical outcomes for a small number of patients with advanced breast cancer treated with weekly infusions of either methotrexate or cisplatin and AZT. Consequently, we conducted a preclinical study of the anti-breast cancer and anti-mammary tumor activity of AZT. Here we have demonstrated that AZT, alone, has a preferential in vitro and in vivo effect on breast and mammary cancer cells. It is 1000 times as potent as an inhibitor of the in vitro growth of the human breast cancer cell line MCF-7 (IC50 = 10 +/- 5 nM) than of the growth of the T-cell leukemia cell line CEM (IC50 = 14 +/- 2 microM). A novel mechanism for this preferential effect on growth is indicated by the 3-4-fold increase in production of phosphorylated AZT (mono-, di-, and triphosphate) in MCF-7 relative to CEM. We extended these in vitro observations to in vivo studies in rats and found that AZT is a potent in vivo inhibitor of the growth of methylnitrosourea-induced rat mammary tumors without any apparent toxic effects on internal organs. These preclinical results demonstrate, for the first time, that AZT has significant anti-breast cancer activity and strongly suggest that the clinical usefulness of this drug is worthy of investigation.

Estrogen-nucleic acid adducts: reaction of 3,4-estrone o-quinone with nucleic acid bases.

Metabolic activation of estradiol leading to the formation of catechol estrogens is believed to be a prerequisite for its genotoxic effects. Previous studies have shown that 3,4-estrone quinone (3,4-EQ) can redox-cycle and is capable of inducing exclusively single-strand DNA breaks in MCF-7 breast cancer cells [Nutter et al. (1991) J. Biol. Chem. 226, 16380-16386]. These studies, however, could not provide conclusive evidence about the mechanism of estrogen carcinogenesis. In order to explore this in more detail, we have shown previously that 3,4-EQ can react with adenine under electrochemical reductive conditions to yield an estrogen-nucleic acid adduct [Abul-Hajj et al. (1995) J. Am. Chem. Soc. 117, 6144-6145]. In this paper, we report the synthesis and identification of seven estrogen-nucleic acid adducts obtained from reaction of 3,4-EQ with adenine, thymine, and cytosine. Initial purification of reaction mixtures using TLC followed by HPLC gave sufficient quantities of reaction products for identification using 1H-NMR and mass spectral determinations. Reaction of 3,4-EQ with adenine, thymine, and cytosine gave the following estrogen-nucleic acid adducts: 8-(4-hydoxyestrone-1-yl)adenine, 3-adenylimino-1,5(10)-estradiene-4,17-dione,4-adenylimino-1, 5(10)-estradiene-3,17-dione, N1- [4-hydroxyestrone-1(alpha,beta)-yl]thymine, N4-(4-hydroxyestrone-1- yl)cytosine, and N4-(4-hydroxy- estrone-2-yl)cytosine. No reaction products were obtained with guanine presumably due to poor solubility in DMF.

Influence of sundrying on the chemical composition, aflatoxin content and fungal counts of two pepper varieties--Capsicum annum and Capsicum frutescens.

Samples of sundried, matured red pepper, Capsicum annum with a moisture content (MC) of 12.7-26.8 percent had on dry weight basis, vitamin C, 5.0-6.4 mg/100 g; crude protein, 0.8-1.2 percent; total soluble solids, 3.3-4.1 percent, and fungal counts of log 4.4-4.5/g. Ordinary matured red C. annum had MC, 75.7-78.2 percent vitamin C, 36.1-38.5 mg/100 g; crude protein, 2.4-2.8 percent; total soluble solids, 9.3-9.9 percent and fungal count of log 3.32-3.39/g. Sundried matured red C. frutescens had corresponding values of 9.4-18.7 percent; 5.8-6.3 mg/100 g; 0.8-1.1 percent; 0.9-2.6 percent and log 3.2-3.4/g. No aflatoxins were detected in sundried, matured red C. frutescens, but aflatoxin B1 values obtained from C. annum varied from non-detectable to 2.2 micrograms/kg. Dominant fungi isolated from C. annum and C. frutescens were Rhizopus oryzaze, Aspergillus niger, A. flavus, Geotrichum candidum and Saccharomyces spp.

Bioequivalence of pyrantel pamoate dosage forms in healthy human subjects.

Drugs that are largely restricted to the gastro-intestinal tract (GIT) for their therapeutic efficacy and that are not substantially absorbed into the body are usually inadequately studied in terms of systemic bioavailability. The possibility of systemic effects requires that bioavailabilities be studied to ensure against enhanced toxicity resulting from formulation differences. Pyrantel pamoate falls into this category. High-performance liquid chromatography was employed in this study to determine plasma levels of pyrantel in nine healthy human subjects after administration of tablet and suspension dosage forms. Mean peak plasma concentrations of 37.56 +/- 9.37, 35.89 +/- 8.94, and 36.22 +/- 10.10 ng mL-1 were obtained following administration of 750 mg pyrantel pamoate in three different formulations. The mean tmax values were 2.02 +/- 0.12, 2.05 +/- 0.356, and 2.05 +/- 0.339 h respectively for the above dosage forms; the respective AUC0-9 values were 81.01 +/- 12.97, 94.59 +/- 17.18, and 101.47 +/- 19.59 h ng mL-1. There was no statistically significant difference between the bioavailabilities of the dosage forms tested. Large inter-subject variations were observed. One subject experienced abdominal discomfort and one experienced dizziness. It was not possible to clearly correlate individual variations in absorption with the observed adverse effect because the number of incidents was low (two out of 27 treatments).

Influence of grain quality, heat, and processing time on the reduction of aflatoxin B1 levels in 'tuwo' and 'ogi': two cereal-based products.

During the production of 'tuwo' from laboratory-contaminated corn (AFB1:150 mcg/kg) and sorghum (AFB1:87.5 mcg/kg) grains, reductions in the aflatoxin-B1 levels of pastes boiled for 30 min and 60 min were found to be 68.0% and 80.8%, respectively. In the preparation of 'ogi' from contaminated corn and sorghum grains, reductions of about 72.5% and 71.4%, respectively, were obtained after fermentation at ambient conditions. Reconstitution of 'ogi' paste into a porridge (akamu) considerably reduced the AFB level.

Effect of processing on the mycoflora and aflatoxin B1 level of a cassava-based product.

Cassava bread was prepared by pre-gelling, battering and baking cassava flour to which were added, in moderate amounts, sugar, yeast solution and edible oil. Baking was at 215 degrees C for 40 min. No mould was isolated from the cassava bread and the mean value of aflatoxin B1 (AFB1) for the three subsamples of cassava bread was 0.03 microgram/kg. The cassava tuber (Manihot esculenta Crantz), which was used for the production of cassava bread had an initial AFB1 level of 1.91 micrograms/kg and the dominant mycoflora were Penicillium oxalicum, Aspergillus flavus, Fusarium spp and some unidentified fungi.

Determination of ampicillin in the presence of cloxacillin.

A spectrophotometric method is described for the assay of ampicillin in the presence of cloxacillin in pharmaceutical preparations. It involves the reaction of hydrolysed ampicillin with formaldehyde in an acidic phosphate buffer (pH 2.5) and measurement of the absorbance of the product at 373 nm after dilution with 2 M sulphuric acid. The method is selective for ampicillin in the presence of cloxacillin. The absorbance had a linear relationship with concentration for the range studied (5-35 micrograms ml-1). By this method the ampicillin content of combined preparations of ampicillin and cloxacillin has been successfully determined in capsules, injections and a syrup.

Effects of sodium metabisulphite, hydrogen peroxide and heat on aflatoxin B1 in lafun and gari--two cassava products.

Sodium metabisulphite and hydrogen peroxide alone or in combination with heat (50-70 degrees C) were found to be effective in degrading aflatoxin B1 (AFB1) in lafun and gari. Hydrogen peroxide (H2O2) at a concentration of 3% in the aqueous phase gave a 12.5% degradation of aflatoxin B1 in lafun and at 50 degrees C, degradation levels of 25% and 50% were obtained with 6.0 and 9.0% H2O2, respectively. When sodium metabisulphite was applied during the production of gari (a fermented cassava product heated to 50-70 degrees C during production) AFB1 degradation levels were found to be 65.8%, 60.9%, 41.5% and 36.6%, respectively, for sodium metabisulphite levels of 1.0%, 0.8%, 0.5% and 0.3%.

Comparative in-vitro antibacterial activity of two brands of antibiotics against clinical isolates of some bacterial genera.

Six brands of ampicillin and four of gentamicin were compared for their in-vitro antibacterial activity against clinical isolates of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The minimum inhibitory concentrations obtained for each brand against each bacterial isolate compared very well with one another, and the kinetics of bactericidal activity showed that the brands of each antibiotic possessed similar activity against the clinical isolates tested.

Comparative bioavailability studies on some brands of ampicillin capsules.

The bioequivalence of two generics of Ampicillin capsules, hitherto untested, were assessed using Penbritin capsules, the innovator's brand, as the reference product. The bioavailability study was carried out in nine healthy volunteers given one capsule (250 mg) of ampicillin in a completely randomized cross-over design. Statistical analysis (ANOVA) of the results indicated that one of the products tested, designated ampicillin (X), was significantly different (p less than 0.05) in its bioavailability compared to Penbritin while the other product, ampicillin (Helm), was not.