Vitamin D receptor alleles and bone mineral density in a normal premenopausal Brazilian female population

Studies on the association between vitamin D receptor (VDR) polymorphism and bone mineral density (BMD) in different populations have produced conflicting results probably due to ethnic differences in the populations studied. The Brazilian population is characterized by a very broad genetic background and a high degree of miscegenation. Of an initial group of 164, we studied 127 women from the city of São Paulo, aged 20 to 47 years (median, 31 years), with normal menses, a normal diet and no history of diseases or use of any medication that could alter BMD. VDR genotype was assessed by PCR amplification followed by BsmI digestion of DNA isolated from peripheral leukocytes. BMD was measured using dual energy X-ray absorptiometry (Lunar DPX) at the lumbar site (L2-L4) and femoral neck. Most of the women (77.6%) were considered to be of predominantly European ancestry (20.6% of them reported also native American ancestry), 12.8% were of African-Brazilian ancestry and 9.6% of Asian ancestry, 41.0% (52) were classified as bb, 48.8% (62) as Bb and 10.2% (13) as BB. The BB, Bb and bb groups did not differ in age, height, weight, body mass index or age at menarche. Lumbar spine BMD was significantly higher in the bb group (1.22 ± 0.16 g/cm²) than in the BB group (1.08 ± 0.14; P<0.05), and the Bb group presented an intermediate value (1.17 ± 0.15). Femoral neck BMD was higher in the bb group (0.99 ± 0.11 g/cm²) compared to Bb (0.93 ± 0.12) and BB (0.90 ± 0.09) (P<0.05). These data indicate that there is a significant correlation between the VDR BsmI genotype and BMD in healthy Brazilian premenopausal females.

Effect of trolox C on cardiac contracture induced by hydrogen peroxide

Hydrogen peroxide (H2O2) perfused into the aorta of the isolated rat heart induces a positive inotropic effect, with cardiac arrhythmia such as extrasystolic potentiation or cardiac contractures, depending on the dose. The last effect is similar to the "stone heart" observed in reperfusion injury and may be ascribed to lipoperoxidation (LPO) of the membrane lipids, to protein damage, to reduction of the ATP level, to enzymatic alterations and to cardioactive compounds liberated by LPO. These effects may result in calcium overload of the cardiac fibers and contracture ("stone heart"). Hearts from male Wistar rats (300-350 g) were perfused at 31oC with Tyrode, 0.2 mM trolox C, 256 mM H2O2 or trolox C + H2O2. Cardiac contractures (baseline elevation of the myograms obtained) were observed when hearts were perfused with H2O2 (Tyrode: 5.9 ± 3.2; H2O2: 60.5 ± 13.9% of the initial value); perfusion with H2O2 increased the LPO of rat heart homogenates measured by chemiluminescence (Tyrode: 3,199 ± 259; H2O2: 5,304 ± 133 cps mg protein-1 60 min-1), oxygen uptake (Tyrode: 0.44 ± 0.1; H2O2: 3.2 ± 0.8 nmol min-1 mg protein-1) and malonaldehyde (TBARS) formation (Tyrode: 0.12 ± 0; H2O2: 0.37 ± 0.1 nmol/ml). Previous perfusion with 0.2 mM trolox C reduced the LPO (chemiluminescence: 4,098 ± 531), oxygen uptake (0.51 ± 0) and TBARS (0.13 ± 0) but did not prevent the H2O2-induced contractures (33.3 ± 16%). ATP (Tyrode: 2.84 ± 0; H2O2: 0.57 ± 0) and glycogen levels (Tyrode: 0.46 ± 0; H2O2: 0.26 ± 0) were reduced by H2O2. Trolox did not prevent these effects (ATP: 0.84 ± 0 and glycogen: 0.27 ± 0). Trolox C is known to be more effective than a -tocopherol or g -tocopherol in reducing LPO though it lacks the phytol portion of vitamin E to be fixed to the cell membranes. Trolox C, unlike vitamin A, did not prevent the glycogen reduction induced by H2O2. Trolox C induced a positive chronotropic effect that resulted in higher energy consumption. The reduction of energy level seemed to be more important than LPO in the mechanism of H2O2-induced contracture

Vitamin D3-induced calcemic and phosphatemic responses in the freshwater mud eel Amphipnous cuchia maintained in different calcium environments

Vitamin D3 (100 ng 100 g body weight-l day-l) was administered intraperitoneally (ip) to the freshwater mud eel Amphipnous cuchia kept in artificial freshwater, calcium-free freshwater, low-calcium freshwater (0.2 mmol/l CaCl2) or calcium-rich freshwater (13.4 mmol/l CaCl2) for 15 days. Analyses of serum calcium and phosphate levels were performed on days 1, 3, 5, 10 and 15 after the beginning of the experiment (six eels from each group at each interval). Administration of vitamin D3 elevated the serum calcium [maximum elevation occurred at day 10 in artificial freshwater (vehicle: 10.55 ± 0.298, vitamin D: 13.90 ± 0.324), low-calcium freshwater (vehicle: 11.17 ± 0.220, vitamin D: 12.98 ± 0.297) and calcium-rich freshwater (vehicle: 11.24 ± 0.373, vitamin D: 14.24 ± 0.208) whereas it occurred at day 5 (vehicle: 8.42 ± 0.253, vitamin D: 11.07 ± 0.328) in calcium-free freshwater] and phosphate levels [maximum elevation at day 15 in artificial freshwater (vehicle: 4.39 ± 0.105, vitamin D: 5.37 ± 0.121), calcium-free freshwater (vehicle: 4.25 ± 0.193, vitamin D: 5.12 ± 0.181), low-calcium freshwater (vehicle: 3.93 ± 0.199, vitamin D: 5.28 ± 0.164) and calcium-rich freshwater (vehicle: 3.77 ± 0.125, vitamin D: 5.46 ± 0.151)] of the fish maintained in the above mentioned environmental media, but the responses were more pronounced in the fish kept in calcium-rich media

Influence of body mass and environmental oxygen tension on the oxygen consumption rates of an enteropneust, Glossobalanus crozieri

The present study deals with a species of enteropneust, Glossobalanus crozieri, focusing on two aspects of its respiration: a) oxygen consumption and body mass, and b) the influence of environmental oxygen tension on the respiratory rate. Preliminarily, the body water content was shown to be 85% of the whole body weight. The regression coefficient of the oxygen consumption on the wet body mass (0.578) seems to agree with the view that in enteropneusts respiration is mainly cutaneous. The respiratory rate was significantly reduced at O2 tensions from 76 mmHg downwards, suggesting conformity rather than regulation

Fractures of the proximal femur: correlation with vitamin D receptor gene polymorphism

Fractures are the feared consequences of osteoporosis and fractures of the proximal femur (FPF) are those that involve the highest morbidity and mortality. Thus far, evaluation of bone mineral density (BMD) is the best way to determine the risk of fracture. Genetic inheritance, in turn, is one of the major determinants of BMD. A correlation between different genotypes of the vitamin D receptor (VDR) and BMD has been recently reported. On this basis, we decided to determine the importance of the determination of VDR genotype in the presence of an osteoporotic FPF in a Brazilian population. We studied three groups: group I consisted of 73 elderly subjects older than 65 years (78.5 ± 7.2 years) hospitalized for nonpathological FPF; group II consisted of 50 individuals older than 65 years (72.9 ± 5.2 years) without FPF and group III consisted of 98 young normal Brazilian individuals aged 32.6 ± 6.6 years (mean ± SD). Analysis of VDR gene polymorphism by restriction fragment length polymorphism (RFLP) was performed by PCR amplification followed by BsmI digestion of DNA isolated from peripheral leukocytes. The genotype distribution in group I was 20.5% BB, 42.5% Bb and 37% bb and did not differ significantly from the values obtained for group II (16% BB, 36% Bb and 48% bb) or for group III (10.2% BB, 47.6% Bb and 41.8% bb). No differences in genotype distribution were observed between sexes or between the young and elderly groups. We conclude that determination of VDR polymorphism is of no practical use for the prediction of FPF. Other nongenetic factors probably start to affect bone mass, the risk to fall and consequently the occurrence of osteoporotic fractures with advancing age.

Differential regulation of vitamin D receptor expression in distinct leukemic cell lines upon phorbol ester-induced growth arrest

A close correlation between vitamin D receptor (VDR) abundance and cell proliferation rate has been shown in NIH-3T3 fibroblasts, MCF-7 breast cancer and in HL-60 myeloblastic cells. We have now determined if this association occurs in other leukemic cell lines, U937 and K562, and if VDR content is related to c-myc expression, which is also linked to cell growth state. Upon phorbol myristate acetate (PMA) treatment, cells from the three lineages (HL-60, U937 and K562) differentiated and expressed specific surface antigens. All cell lines analyzed were growth inhibited by PMA and the doubling time was increased, mainly due to an increased fraction of cells in the G0/G1 phase, as determined by flow cytometry measurements of incorporated bromodeoxyuridine and cell DNA content. C-myc mRNA expression was down-regulated and closely correlated to cell growth arrest. However, VDR expression in leukemic cell lines, as determined by immunofluorescence and Northern blot assays, was not consistently changed upon inhibition of cell proliferation since VDR levels were down-regulated only in HL-60 cells. Our data suggest that VDR expression cannot be explained simply as a reflection of the leukemic cell growth state.

Oxygen consumption of rats with broad intestinal resection

The study was performed to investigate possible alterations in oxygen consumption in an animal model with broad intestinal resection. Oxygen consumption and the thermal effect of a short meal were measured in rats subjected to short bowel syndrome. Four groups of rats were used. Group I was the control group, group II was sham operated, group III was submitted to 80% jejunum-ileum resection, and group IV was submitted to 80% jejunum-ileum resection with colon interposition. Ninety days after surgery, oxygen consumption was measured over a period of 6 h with the animals fasted overnight. The thermal effect of feeding was determined in another session of oxygen consumption measurement in animals fasted for 12 h. A 12-kcal meal was then introduced into the animal chamber and oxygen consumption was measured for a further 4 h. No differences in fasting oxygen consumption or in the thermal effect of the meal were detected among the groups studied. It is concluded that short bowel syndrome does not affect the overall energy expenditure of rats.

Protective role of antioxidant vitamin E and catechin on idarubicin-induced cardiotoxicity in rats

Idarubicin is an anthracycline antibiotic extensively used in acute leukemia. In the present study we investigated whether vitamin E and catechin can reduce the toxic effects of idarubicin. Vitamin E (200 IU kg-1 week-1), catechin (200 mg kg-1 week-1), idarubicin (5 mg kg-1 week-1), idarubicin + vitamin E (200 IU kg-1 week-1), and idarubicin + catechin (200 mg kg-1 week-1) combinations were given to male Sprague-Dawley rats weighing 210 to 230 g (N = 6/group). Idarubicin-treated animals exhibited a decrease in body and heart weight, a decrease in myocardial contractility, and changes in ECG parameters (P<0.01). Catechin + idarubicin- and vitamin E + idarubicin-treated groups exhibited similar alterations, but changes were attenuated in comparison to those in cardiac muscle of idarubicin-treated rats (P<0.05). Superoxide dismutase and catalase activity was reduced in the idarubicin-treated group (P<0.05). Glutathione peroxidase levels were decreased in the idarubicin-treated group (P<0.05) and reached maximum concentrations in the catechin- and catechin + idarubicin-treated groups compared to control (P<0.01). Malondialdehyde activity was decreased in the catechin + idarubicin-treated groups compared to control and increased in the other groups, reaching maximum concentrations in the vitamin E-treated group (P<0.01). In electron microscopy studies, swelling of the mitochondria and dilatation of the sarcoplasmic reticulum of myocytes were observed in the idarubicin-treated groups. In groups that were given idarubicin + vitamin E and idarubicin + catechin, the only morphological change was a weak dilatation of the sarcoplasmic reticulum. We conclude that catechin and vitamin E significantly reduce idarubicin-induced cardiotoxicity in rats.

Low ethanol consumption increases insulin sensitivity in Wistar rats

Several human studies suggest that light-to-moderate alcohol consumption is associated with enhanced insulin sensitivity, but these studies are not free of conflicting results. To determine if ethanol-enhanced insulin sensitivity could be demonstrated in an animal model, male Wistar rats were fed a standard chow diet and received drinking water without (control) or with different ethanol concentrations (0.5, 1.5, 3, 4.5 and 7%, v/v) for 4 weeks ad libitum. Then, an intravenous insulin tolerance test (IVITT) was performed to determine insulin sensitivity. Among the ethanol groups, only the 3% ethanol group showed an increase in insulin sensitivity based on the increase of the plasma glucose disappearance rate in the IVITT (30%, P<0.05). In addition, an intravenous glucose tolerance test (IVGTT) was performed in control and 3% ethanol animals. Insulin sensitivity was confirmed in 3% ethanol rats based on the reduction of insulin secretion in the IVGTT (35%, P<0.05), despite the same glucose profile. Additionally, the 3% ethanol treatment did not impair body weight gain or plasma aspartate aminotransferase and alanine aminotransferase activities. Thus, the present study established that 3% ethanol in the drinking water for 4 weeks in normal rats is a model of increased insulin sensitivity, which can be used for further investigations of the mechanisms involved.

Effect of the consumption of tomato paste on plasma prostate-specific antigen levels in patients with benign prostate hyperplasia

The consumption of tomatoes and tomato products has been associated with a reduced risk of prostate cancer. We observed a decrease of 10.77% in prostate-specific antigen (PSA) levels in patients with benign prostate hyperplasia who were submitted to daily ingestion of tomato paste. This was an experimental rather than a controlled study with a sample of 43 men ranging in age from 45 to 75 years, all with histological diagnoses of benign prostate hyperplasia and plasma PSA levels of 4-10 ng/mL. All patients received 50 g of tomato paste once a day for 10 consecutive weeks and PSA levels were analyzed before, during and after the consumption of tomato paste. ANOVA for repeated measures was used to compare PSA levels before, during and after the consumption of tomato paste. The mean ± SD PSA level was 6.51 ± 1.48 ng/mL at baseline and 5.81 ± 1.58 ng/mL (P = 0.005) after 10 weeks. Acceptance was good in 88.3, regular in 9.3, and poor in 2.3% of the patients. Dietary ingestion of 50 g of tomato paste per day for 10 weeks significantly reduced mean plasma PSA levels in patients with benign prostate hyperplasia, probably as a result of the high amount of lycopene in tomato paste. This was not a prostate cancer prevention study, but showed some action of tomato paste in prostate biology. The development of prostate cancer is typically accompanied by an increase in plasma PSA levels, thus any intervention that affects plasma PSA levels can suggest an impact in the progression of disease.

Food consumption by young adults living in Ribeirão Preto, SP, 2002/2004

There is evidence showing a close relationship between diet and the occurrence of non-communicable chronic diseases. The present study assessed food consumption in a 2002/2004 cohort of young adults born in 1978/79 in Ribeirão Preto, SP, Brazil. The composition of the habitual diet consumed by a sample of 2063 individuals aged 23-25 years was analyzed using a validated semi-quantitative food frequency questionnaire based on studies of prevention of non-communicable chronic diseases. The Dietsys software was used for dietary calculations. In terms of WHO/2003 recommendations, there was a high mean daily consumption of energy from fat (consumption: 35.4%; recommendation: 15-30%), a low mean intake of energy from carbohydrates (47.5%; 55-75%) and a low mean consumption of total fibers (15.2 g; >25 g). Mean intake of energy from fatty acids (10%; <10%) and protein (15.6%; 10-15%) was within recommended limits. When compared to the recommendations of the food pyramid adapted to the Brazilian population, adequate intake was observed only regarding the meat group (consumption: 1.9 portions; recommended: 1-2). There was a low consumption of vegetables (2.9; 4-5), fruits (1.2; 3-5), breads (3.6; 6-9), and dairy products (1.7; 3), with excessive fat and sugar intake (5.7; 1-2). We conclude that the inadequate food consumption observed in this young population may be associated with the development of excess weight and may contribute to the triggering of non-communicable chronic diseases.

Protection against cephalosporin-induced lipid peroxidation and nephrotoxicity by (+)-cyanidanol-3 and vitamin E

The ability of the clinically used cephalosporins: cephalothin, cefotaxime and cefotiam to induce lipid peroxidation (LPO) and renal damage was compared to that of nephrotoxic cephaloridine under in vivo conditions. Glutathione was measured in rat liver or in renal cortex as non-protein sulfhydryls. LPO was measured in plasma, renal cortex and liver by the generation of malondialdehyde or as the increase in renal cortical concentration of conjugated dienes. Impairment of renal function was measured as the decrease in renal cortical accumulation of the organic anion p-aminohippurate (PAH). Administration of cephalosporins to rats as a single dose (2000 mg/kg, ip) induced a significant glutathione-depletion in the renal cortex with cephaloridine, and in the liver with cephaloridine, cephalothin and cefotiam. Treatment of rats with cephaloridine, cephalothin and cefotiam (200, 500, or 1000 mg kg-1 day-1, ip) for 5 days resulted in a dose-dependent increase of LPO in the renal cortex. While cephaloridine induced the highest concentration of conjugated diene, cefotaxime had no effect. Measurements of PAH accumulation in renal cortical slices from cephalosporin-treated rats showed a dose-dependent decrease in the renal cortical accumulation of PAH. Pretreatment with the antioxidants vitamin E or cyanidanol (400 mg kg-1 day-1, ip) 1 h before treatment with cephaloridine, cephalothin or cefotiam (1000 mg kg-1 day-1, ip) for 3 days inhibited cephalosporin-induced LPO and significantly reduced the impairment of renal cortical accumulation of PAH. The potential of different cephalosporins for inducing LPO and reducing PAH accumulation was ranked as follows: cephaloridine > cephalothin > cefotiam > cefotaxime.

Vitamin B1 and B6 in the malaria parasite: requisite or dispensable?

Vitamins are essential compounds mainly involved in acting as enzyme co-factors or in response to oxidative stress. In the last two years it became apparent that apicomplexan parasites are able to generate B vitamers such as vitamin B1 and B6 de novo. The biosynthesis pathways responsible for vitamin generation are considered as drug targets, since both provide a high degree of selectivity due to their absence in the human host. This report updates the current knowledge about vitamin B1 and B6 biosynthesis in malaria and other apicomplexan parasites. Owing to the urgent need for novel antimalarials, the significance of the biosynthesis and salvage of these vitamins is critically discussed in terms of parasite survival and their exploitation for drug development.

Genetic polymorphisms in vitamin D receptor, vitamin D-binding protein, Toll-like receptor 2, nitric oxide synthase 2, and interferon-γ genes and its association with susceptibility to tuberculosis

Mycobacterium tuberculosis kills more people than any other single pathogen, with an estimated one-third of the world's population being infected. Among those infected, only 10% will develop the disease. There are several demonstrations that susceptibility to tuberculosis is linked to host genetic factors in twins, family and associated-based case control studies. In the past years, there has been dramatic improvement in our understanding of the role of innate and adaptive immunity in the human host defense to tuberculosis. To date, attention has been paid to the role of genetic host and parasitic factors in tuberculosis pathogenesis mainly regarding innate and adaptive immune responses and their complex interactions. Many studies have focused on the candidate genes for tuberculosis susceptibility ranging from those expressed in several cells from the innate or adaptive immune system such as Toll-like receptors, cytokines (TNF-α, TGF-β, IFN-γ, IL-1b, IL-1RA, IL-12, IL-10), nitric oxide synthase and vitamin D, both nuclear receptors and their carrier, the vitamin D-binding protein (VDBP). The identification of possible genes that can promote resistance or susceptibility to tuberculosis could be the first step to understanding disease pathogenesis and can help to identify new tools for treatment and vaccine development. Thus, in this mini-review, we summarize the current state of investigation on some of the genetic determinants, such as the candidate polymorphisms of vitamin D, VDBP, Toll-like receptor, nitric oxide synthase 2 and interferon-γ genes, to generate resistance or susceptibility to M. tuberculosis infection.

Education, tobacco smoking, alcohol consumption, and IL-2 and IL-6 gene polymorphisms in the survival of head and neck cancer

The association of education, tobacco smoking, alcohol consumption, and interleukin-2 (IL-2 +114 and -384) and -6 (IL-6 -174) DNA polymorphisms with head and neck squamous cell carcinoma (HNSCC) was investigated in a cohort study of 445 subjects. IL-2 and IL-6 genotypes were determined by real-time PCR. Cox regression was used to estimate hazard ratios (HR) and 95% confidence intervals (95%CI) of disease-specific survival according to anatomical sites of the head and neck. Mean age was 56 years and most patients were males (87.6%). Subjects with 5 or more years of schooling had better survival in larynx cancer. Smoking had no effect on HNSCC survival, but alcohol consumption had a statistically significant effect on larynx cancer. IL-2 gene +114 G/T (HR = 0.52; 95%CI = 0.15-1.81) and T/T (HR = 0.22; 95%CI = 0.02-3.19) genotypes were associated with better survival in hypopharynx cancer. IL-2 +114 G/T was a predictor of poor survival in oral cavity/oropharynx cancer and larynx cancer (HR = 1.32; 95%CI = 0.61-2.85). IL-2 -384 G/T was associated with better survival in oral cavity/oropharynx cancer (HR = 0.80; 95%CI = 0.45-1.42) and hypopharynx cancer (HR = 0.68; 95%CI = 0.21-2.20), but an inverse relationship was observed for larynx cancer. IL-6 -174 G/C was associated with better survival in hypopharynx cancer (HR = 0.68; 95%CI = 0.26-1.78) and larynx cancer (HR = 0.93; 95%CI = 0.42-2.07), and C/C reduced mortality in larynx cancer. In general, our results are similar to previous reports on the value of education, smoking, alcohol consumption, and IL-2 and IL-6 genetic polymorphisms for the prognosis of HNSCC, but the risks due to these variables are small and estimates imprecise.