Postmitotic tissue selenium and manganese levels in alpha-lipoic acid-supplemented aged rats

Redistribution of selenium and manganese in postmitotic tissues of alpha-lipoic acid-supplemented aged rats has been proposed to contribute to metal-catalyzed protein oxidation. DL-Alpha-lipoic acid (LA) (100 mg/[kg body wt.day]) was administered intraperitoneally to the Sprague-Dawley rats for 14 days. Serum selenium levels were lowered in the aged rats with LA supplementation compared with those of the rats without LA supplementation. Similarly, the selenium levels of the heart, brain and muscle were found to be significantly lower in LA-supplemented rats when compared to control rats. On the other hand, serum manganese levels were not changed in the aged rats with LA supplementation compared with those of the rats without LA supplementation. The heart manganese levels detected in LA-supplemented rats were significantly lower than controls. Manganese levels of the brain and muscle tissues were increased in the aged rats with LA supplementation compared with those of the rats without LA supplementation. Based on the findings of our study, we conclude that LA may exhibit pro-oxidant effect depending on the altered selenium and manganese homeostasis. Thus, our results stress the importance of monitoring the dose of LA supplementation and serum selenium levels, duration of treatment and its potential harmful pro-oxidant effects in the postmitotic tissues of aged rats.     

Vaginal intraepithelial neoplasia and the Pap smear

OBJECTIVE: To assess the sensitivity of the vaginal smear cytologic examination in detecting vaginal intraepithelial neoplasia (VAIN) and to evaluate the cytologic findings of cases of VAIN. STUDY DESIGN: Cases with a histologic diagnosis of VAIN were identified from the Barnes-Jewish Hospital South and North Campus over a period of five and nine years, respectively. Only posthysterectomy patients with a tissue biopsy diagnosis of VAIN and with a vaginal smear obtained within three months of the biopsy were included in the study. Pertinent clinical information was obtained by reviewing the medical records. Two pathologists reviewed the pathologic samples. RESULTS: Thirty-five vaginal smears from 31 posthysterectomy patients were included in the study. The mean age was 57 years (range, 29-84). The cytologic diagnoses of smears from patients with VAIN included: high grade squamous intraepithelial lesion (19 cases), low grade squamous intraepithelial lesion (10 cases), atypical squamous cells of uncertain significance (5 cases) and negative for malignancy (1 case). CONCLUSION: The sensitivity of the vaginal smear cytologic examination in detecting VAIN is 83%. Obscuring inflammation contributed to false negative diagnoses in two cases.     

Metabolism of [11-3H]retinyl acetate in liver tissues of vitamin A-sufficient, -deficient and retinoic acid-supplemented rats

A study was conducted on the incorporation of [11-3H]retinyl acetate into various retinyl esters in liver tissues of rats either vitamin A-sufficient, vitamin A-deficient or vitamin A-deficient and maintained on retinoic acid. Further, the metabolism of [11-3H]retinyl acetate to polar metabolites in liver tissues of these three groups of animals was investigated. Retinol metabolites were analyzed by high-performance liquid chromatography. In vitamin A-sufficient rat liver, the incorporation of radioactivity into retinyl palmitate and stearate was observed at 0.25 h after the injection of the label. The label was further detected in retinyl laurate, myristate, palmitoleate, linoleate, pentadecanoate and heptadecanoate 3 h after the injection. The specific radioactivities (dpm/nmol) of all retinyl esters increased with time. However, the rate of increase in the specific radioactivity of retinyl laurate was found to be significantly higher (66-fold) than that of retinyl palmitate 24 h after the injection of the label. 7 days after the injection of the label, the specific radioactivity between different retinyl esters were found to be similar, indicating that newly dosed labelled vitamin A had now mixed uniformly with the endogenous pool of vitamin A in the liver. The esterification of labelled retinol was not detected in liver tissues of vitamin A-deficient or retinoic acid-supplemented rats at any of the time point studied. Among the polar metabolites analyzed, the formation of [3H]retinoic acid from [3H]retinyl acetate was found only in vitamin A-deficient rat liver 24 h after the injection of the label. A new polar metabolite of retinol (RM) was detected in liver of the three groups of animals. The formation of 3H-labelled metabolite RM from [3H]retinyl acetate was not detected until 7 days after the injection of the label in the vitamin A-sufficient rat liver, suggesting that metabolite RM could be derived from a more stable pool of vitamin A.     

Fertility and blood progesterone levels following LHRH-induced superovulation in FSH-treated anestrous goats

Twenty mature, mixed-breed, seasonally anestrous female goats were used to study the effects of luteinizing hormone releasing hormone (LHRH) on ovulation rate, fertility, and blood progesterone levels following norgestomet-induced estrus and follicle stimulating hormone (FSH) treatments. Each goat received 6 mg norgestomet by subcutaneous (sc) implant and 3 mg intramuscularly, along with an intramuscular (im) injection of 5 mg estradiol valerate. Four injections of FSH were given for 2 d in divided doses of 10, 10, 5 and 5 mg im every 12 h, starting at 24 h before implant removal. The goats were randomly assigned to 1 of 2 equal treatment groups, and were treated with 2 intravenous (iv) injections of either 0.9% saline (control) or 300 ug LHRH at 24 and 48 h after the removal of the implants. All the goats exhibited estrus within 24 or 36 h of implant withdrawal and were mated to bucks of proven fertility. At laparotomy on Day 7 or 8 after the removal of the implants, the mean number of unovulated follicles was higher (P<0.05) in Group I than in Group II. The mean number of corpora lutea (ovulation rate), the total number of embryos and the number of normal embryos recovered were higher (P<0.05) in LHRH-treated does than in the controls. Treatment with LHRH resulted in 72.14% fertility (mean number of CL = 14) as compared with the controls with 64.29% fertility (mean number of CL = 2.8). The embryos obtained from goats in Group II were of more uniform developmental age regardless of the day of embryo collection, as compared with those of the controls. Plasma progesterone levels were significantly increased on Days 4 to 6 in both treatment groups. The results of this study have demonstrated that the FSH and LHRH treatment regimen increased follicular development, ovulation rate and blood progesterone levels in norgestomet-treated anestrous goats. Moreover, LHRH treatment enhanced fertility, and improved embryo quality as indicated by the significantly higher total number of embryos as well as the higher (P<0.05) number of normal recoverable embryos.     

The biological activity of rat intestinal retinoic acid metabolites in the vaginal smear assay

Vitamin A-deficient rats were given a single intrajugular injection of 1 mg all-trans-[11-³H]retinoic acid and 3 h later the rats were killed. The small intestines were extracted and chromatographed by high-performance liquid chromatography to yield distinct metabolites. These were quantitated using the assumption that the specific activity of the metabolite is equal to that of the parent [³H]retinoic acid. The biological activity of all discernible metabolities was determined in the vitamin A-deficient female rat by vaginal smear assay. Retinoic acid and retinoyl-β-glucuronide from the preparation had equal activity while no activity was found for any of the other metabolite fractions. Thus, no evidence for an unknown metabolite having potent epithelial differentiating activity could be found in this target tissue of vitamin A action.     

Benzonidazole levels in blood vary with age in rats

Benznidazole (Bz) exhibits toxic side effects in animal studies and clinical use. Reductive metabolism of Bz in liver microsomes modulates the duration of its chemotherapeutic effect and its toxicity. The rate of this metabolism depends on age and is less intense in newborns and youngsters than in adults. In the present study, we determined Bz blood levels in rats of different ages that received Bz intragastrically (100 mg/kg). We developed and validated a high-pressure liquid chromatography with UV detector method for determination of Bz levels in whole blood. Bz levels were significantly higher and persisted for longer periods of time in the blood of young rats when compared to that of adult animals.     

The effects of estrogen and progesterone on blood glutamate levels: evidence from changes of blood glutamate levels during the menstrual cycle in women

The gonadal steroids estrogen and progesterone have been shown to have neuroprotective properties against various neurodegenerative conditions. Excessive concentrations of glutamate have been found to exert neurotoxic properties. We hypothesize that estrogen and progesterone provide neuroprotection by the autoregulation of blood and brain glutamate levels. Venous blood samples (10 ml) were taken from 31 men and 45 women to determine blood glutamate, estrogen, progesterone, glucose, glutamate-pyruvate transaminase (GPT), and glutamate-oxaloacetate transaminase (GOT) levels, collected on Days 1, 7, 12, and 21 of the female participants' menstrual cycle. Blood glutamate concentrations were higher in men than in women at the start of menstruation (P < 0.05). Blood glutamate levels in women decreased significantly on Days 7 (P < 0.01), 12 (P < 0.001), and 21 (P < 0.001) in comparison with blood glutamate levels on Day 1. There was a significant decrease in blood glutamate levels on Days 12 (P < 0.001) and 21 (P < 0.001) in comparison with blood glutamate levels on Day 7. Furthermore, there was an increase in blood glutamate levels on Day 21 compared with Day 12 (P < 0.05). In women, there were elevated levels of estrogen on Days 7 (P < 0.05), 12, and 21 (P < 0.001), and elevated levels of progesterone on Days 12 and 21 (P < 0.001). There were no differences between men and women with respect to blood glucose concentrations. Concentrations of GOT (P < 0.05) and GPT (P < 0.001) were significantly higher in men than in women during the entire cycle. The results of this study demonstrate that blood glutamate levels are inversely correlated to levels of plasma estrogen and progesterone.