Simultaneous regulation of lactate production and fatty acid metabolism by Resveratrol in rat Sertoli cells.

Sertoli cells provide structural and nutritional support for germ cell development. They actively metabolize glucose and convert it into lactate, which is an important source of energy for germ cells. They also oxidize fatty acids (FA), stored as triacylglycerides (TAGs) within lipid droplets (LD), to fulfill their own energy requirements. So, the combined regulation of lactate production and FA metabolism may be relevant to the physiology of seminiferous tubules. Resveratrol (RSV) is a nutritional supplement found primarily in red grape skin that exhibits multiple beneficial health effects: it is cardioprotective, anti-inflammatory, anticancer, and antiaging. The aim of this study was to evaluate the effect of RSV in Sertoli cells lactate production and lipid metabolism. Sertoli cell cultures obtained from 20-day-old rats were incubated for different times with 10 or 50 µM RSV. RSV treatment increased lactate production and glucose consumption. These increments were accompanied by a rise in GLUT1 expression, which is the main glucose transporter in Sertoli cells. On the other hand, RSV decreased LD content and TAG levels. In addition, an increase in ATGL and FAT/CD36 mRNA levels was observed, which suggests augmented cytoplasmatic FA availability. RSV treatment also increased P-ACC levels, which might indicate that RSV promotes FA transport into the mitochondria to be oxidized. An enhanced expression of LCAD and MCAD, enzymes that participate in the oxidation of FA, was also observed. Altogether, these results suggest that RSV simultaneously regulates Sertoli cells lactate production and lipid metabolism, ensuring an adequate energetic balance both in germ and Sertoli cells.

PPARγ activation regulates lipid droplet formation and lactate production in rat Sertoli cells.

Sertoli cells provide the structural and nutritional support for germ cell development; they actively metabolize glucose and convert it to lactate, which is an important source of energy for germ cells. Furthermore, Sertoli cells can oxidize fatty acids, a metabolic process that is assumed to fulfill their own energy requirements. Fatty acids are stored as triacylglycerides within lipid droplets. The regulation of fatty acid storage in conjunction with the regulation of lactate production may thus be relevant to seminiferous tubule physiology. Our aim is to evaluate a possible means of regulation by the PPARγ activation of lipid droplet formation and lactate production. Sertoli cell cultures obtained from 20-day-old rats were incubated with Rosiglitazone (10 µM), a PPARγ activator, for various periods of time (6, 12, 24 and 48 h). Increased triacylglycerides levels and lipid droplet content were observed, accompanied by a rise in the expression of genes for proteins involved in fatty acid storage, such as the fatty acid transporter Cd36, glycerol-3-phosphate-acyltransferases 1 and 3, diacylglycerol acyltransferase 1 and perilipins 1, 2 and 3, all proteins that participate in lipid droplet formation and stabilization. However, PPARγ activation increased lactate production, accompanied by an augmentation in glucose uptake and Glut2 expression. These results taken together suggest that PPARγ activation in Sertoli cells participates in the regulation of lipid storage and lactate production thereby ensuring simultaneously the energetic metabolism for the Sertoli and germ cells.

Activation of PPAR α and PPAR ß/δ regulates Sertoli cell metabolism.

The purpose of this study was to evaluate the existence of a possible simultaneous regulation of fatty acid (FA) metabolism and lactate production by PPAR α and PPAR ß/δ activation in Sertoli cells (SC). SC cultures obtained from 20-day-old rats were incubated with WY14643 or GW0742-pharmacological activators of PPAR α and PPAR ß/δ respectively. The fatty acid transporter CD36, carnitine palmitoyltransferase 1, long- and medium-chain 3-hydroxyacyl-CoA dehydrogenases mRNA levels were analyzed. An increase in the above-mentioned genes in response to activation of both nuclear receptors was observed. Additionally, PPAR ß/δ activation increased lactate production as a consequence of increased pyruvate availability by inhibiting the Pyruvate Dehydrogenase Complex. Altogether, these results suggest that in SC, PPAR α activation participates in the regulation of FA metabolism. On the other hand, PPAR ß/δ activation regulates FA metabolism and lactate production ensuring simultaneously the energetic metabolism for SC and germ cells.

Different signal transduction pathways elicited by basic fibroblast growth factor and interleukin 1ß regulate CREB phosphorylation in Sertoli cells.

BACKGROUND AND AIM: Basic fibroblast growth factor (bFGF) and interleukin 1ß (IL1ß) belong to the set of intratesticular regulators that provide for the fine-tuning of processes implicated in the maintenance of spermatogenesis. The aim of this study was to investigate if bFGF and IL1ß activate CREB, what signaling pathways may be participating and the possible relationship between CREB activation and the regulation of Sertoli cell function. METHODS: Twenty-day-old rat Sertoli cell cultures were used. RESULTS: Cultures stimulated with bFGF and IL1ß produced a time-dependent increment in phosphorylated CREB levels that reached maximal values in 5- and 15-minute incubations respectively. MEK inhibitors--PD98059 and U0126--blocked the effect of bFGF on phosphorylated CREB while a p38-MAPK inhibitor--SB203580--blocked the effect of IL1ß on phosphorylated CREB. A possible correlation between CREB regulation and two Sertoli cell-differentiated functions, Ldh A and transferrin expression, was explored. PD98059 blocked the ability of bFGF to stimulate Ldh A expression and SB203580 blocked the ability of IL1ß to stimulate Ldh A expression and LDH activity. Concerning transferrin, PD98059 and U0126 were able to inhibit the ability of bFGF to stimulate its secre tion. On the contrary, SB203580 was unable to block IL1ß induced increase in transferrin secretion suggesting that the p38-MAPK pathway does not participate in the mechanism of action of the cytokine to regulate transferrin. CONCLUSIONS: The results presented herein suggest that CREB is stimulated in response to bFGF and IL1ß through p42/p44-MAPK and p38-MAPK pathways and that this transcription factor may be partially responsible for the regulation of Sertoli cell function.

Adenosine regulates Sertoli cell function by activating AMPK.

This work evaluates adenosine effects on Sertoli cell functions, which are different to those resulting from occupancy of purinergic receptors. The effects of adenosine and N(6)-cyclohexyladenosine (CHA) - an A(1) receptor agonist resistant to cellular uptake - on Sertoli cell physiology were compared. Adenosine but not CHA increased lactate production, glucose uptake, GLUT1, LDHA and MCT4 mRNA levels, and stabilized ZO-1 protein at the cell membrane. These differential effects suggested a mechanism of action of adenosine that cannot be solely explained by occupancy of type A(1) purinergic receptors. Activation by adenosine but not by CHA of AMPK was observed. AMPK participation in lactate production and ZO-1 stabilization was confirmed by utilizing specific inhibitors. Altogether, these results suggest that activation of AMPK by adenosine promotes lactate offer to germ cells and cooperates in the maintenance of junctional complex integrity, thus contributing to the preservation of an optimum microenvironment for a successful spermatogenesis.

Expression of caveolin-1 in rat Leydig cells

Caveolin-1, the first member of caveolin family reported, is recognized as the structural component of caveola, a plasma membrane invagination or vesicles that are a subcompartment distinct from clathrin-coated pits. This protein is also known to be involved in cholesterol trafficking. The aim of this study was to determine the expression of caveolin-1 in adult rat Leydig cells. Testis sections incubated with an antibody to caveolin-1 showed, by immunohistochemistry, a moderate number of Leydig cells with different degrees of immunoreaction and a strong reaction in endothelial cells and in the lamina propia of seminiferous tubules.Caveolin- 1 was detected in the cell cytoplasm with a granular pattern and on the cell surface of Leydig cells cultured 24 h on uncoated, laminin-1 or type IV collagen coated coverslips. We also observed a milder reaction in 3 h cultures. Immunoreaction was also detected in Leydig cells with an antibody to tyrosine-phosphorylated caveolin-1. By double immunofluorescent technique, we observed co-localization of caveolin- I and 313-hydroxysteroid dehydrogenase. Western blot analysis revealed a band of about 22 kDa molecular weight that was recognized with both caveolin-1 and tyrosine-phosphocaveolin-1 antibodies. Caveolin-l is one of a few proteins with ademonstrated ability to bind cholesterol in vivo. In this context, the presence of caveolin- in Leydig cells may be related to cholesterol traffic--a rate limiting step in steroid biosynthesis.

Expression of caveolin-1 in rat Leydig cells

Caveolin-1, the first member of caveolin family reported, is recognized as the structural component of caveola, a plasma membrane invagination or vesicles that are a subcompartment distinct from clathrin-coated pits. This protein is also known to be involved in cholesterol trafficking. The aim of this study was to determine the expression of caveolin-1 in adult rat Leydig cells. Testis sections incubated with an antibody to caveolin-1 showed, by immunohistochemistry, a moderate number of Leydig cells with different degrees of immunoreaction and a strong reaction in endothelial cells and in the lamina propia of seminiferous tubules.Caveolin- 1 was detected in the cell cytoplasm with a granular pattern and on the cell surface of Leydig cells cultured 24 h on uncoated, laminin-1 or type IV collagen coated coverslips. We also observed a milder reaction in 3 h cultures. Immunoreaction was also detected in Leydig cells with an antibody to tyrosine-phosphorylated caveolin-1. By double immunofluorescent technique, we observed co-localization of caveolin- I and 313-hydroxysteroid dehydrogenase. Western blot analysis revealed a band of about 22 kDa molecular weight that was recognized with both caveolin-1 and tyrosine-phosphocaveolin-1 antibodies. Caveolin-l is one of a few proteins with ademonstrated ability to bind cholesterol in vivo. In this context, the presence of caveolin- in Leydig cells may be related to cholesterol traffic--a rate limiting step in steroid biosynthesis.(AU)

Pituitary-ovarian axis during lactational amenorrhoea. II. Longitudinal assessment of serum FSH polymorphism before and after recovery of menstrual cycles.

BACKGROUND: The association of normal serum levels of immunoassayable gonadotrophins with anovulation during lactational amenorrhoea (LA) has not been fully explained. METHODS: Serum FSH polymorphism was analysed in 10 women during LA between days 60 and 70 post-partum and again, in the mid-follicular phase (MFP), after resuming menstrual cyclicity. FSH microheterogeneity was characterized according to charge, using preparative isoelectric focusing, and according to the inner structure of carbohydrate chains, using lectin chromatography. RESULTS: A significantly higher proportion of FSH charge isoforms isolated below pH 4.10 and a lower proportion of FSH isoforms bearing highly branched oligosaccharides were observed during LA when compared to MFP. Further analysis with higher resolution showed that FSH charge isoforms, isolated in the lower pH range in LA, corresponded to FSH molecules bearing highly branched and biantennary oligosaccharides. FSH isoforms bearing hybrid-type oligosaccharides were only present during LA. The circulating FSH isoform mix was significantly less bioactive in LA than in MFP. LA is characterized by a more acidic mix of FSH isoforms, containing hormone bearing less processed oligosaccharides, with decreased biopotency in comparison with the follicular phase. CONCLUSIONS: This FSH microheterogeneity may be one of the critical factors contributing to incomplete follicular development and anovulation during LA.

FSH activates phosphatidylinositol 3-kinase/protein kinase B signaling pathway in 20-day-old Sertoli cells independently of IGF-I.

The gonadotropin FSH plays a key role in the control of Sertoli cell function. The FSH molecular mechanism of action is best recognized for its stimulation of the adenylyl cyclase/cAMP pathway. However, other signaling events have also been demonstrated in Sertoli cells. We have recently presented evidence that FSH can stimulate the phosphatidylinositol 3-kinase/protein kinase B (PI3K/PKB) pathway in 20-day-old Sertoli cells. At the same time, it was proposed that in 8-day-old Sertoli cells the effects of FSH on phosphorylated PKB (P-PKB) levels can be explained by a combination of increased secretion of endogenous IGF-I, decreased IGF-binding protein-3 (IGFBP-3) production, and a synergistic action of FSH on IGF-I-dependent PI3K activation. The aim of the present study was to determine whether the effect of FSH on 20-day-old Sertoli cells is mediated by IGF-I secretion. Twenty-day-old rat Sertoli cell cultures were used. FSH stimulation produced a time-dependent increment in P-PKB levels reaching maximal values in 60-min incubations. IGF-I stimulation was also time-dependent reaching maximal values in 15-min incubations. On the other hand, stimulation of the cultures with FSH showed time-dependent inhibition in phosphorylated mitogen-activated protein kinase (P-MAPK) levels. In sharp contrast, stimulation of the cultures with IGF-I showed time-dependent increments in P-MAPK levels reaching maximal stimulus in 15-min incubations. In order to rule out an IGF-I action on FSH stimulation of P-PKB levels, the effect of a specific IGF-I antibody on the ability of both hormones to increase P-PKB levels was evaluated. As expected, the antibody inhibited IGF-I stimulation of P-PKB levels. However, simultaneous addition of an IGF-I antibody with FSH did not modify the ability of the hormone to increase P-PKB levels. The next set of experiments intended to analyze the relevance of a PI3K/PKB pathway to two biological responses of Sertoli cells to FSH and IGF-I. The PI3K inhibitor, wortmannin, dose-dependently decreased FSH-stimulated lactate and transferrin production. On the other hand, wortmannin was not able to modify the ability of IGF-I to stimulate these metabolic events. In addition, the analysis of the participation of a MAPK pathway in IGF-I regulation of Sertoli cell biological responses showed that the MAPK kinase inhibitors, PD98059 and U0126, decreased IGF-I-stimulated transferrin secretion while not modifying IGF-I-stimulated lactate levels. In summary, results obtained so far support the hypothesis that FSH action on P-PKB levels and Sertoli cell metabolism in 20-day-old animals is not mediated by autocrine regulation of an IGF-I/ IGFBP-3 axis as previously proposed in 8-day-old Sertoli cells.

Assessment of the roles of mitogen-activated protein kinase and phosphatidyl inositol 3-kinase/protein kinase B pathways in the basic fibroblast growth factor regulation of Sertoli cell function.

Basic fibroblast growth factor (bFGF) belongs to the large set of intratesticular regulators that provide the fine tuning of cellular processes implicated in the maintenance of spermatogenesis. The aim of the present study was to determine the participation of mitogen-activated protein kinase (MAPK) and phosphatidyl inositol 3-kinase/protein kinase B (PI3K/PKB) pathways in bFGF regulation of Sertoli cell function. Twenty-day-old rat Sertoli cell cultures were used. Stimulation of the cultures with bFGF showed a time-dependent increment in phosphorylated MAPK and PKB levels that reached maximal values in 5-min incubations. MAPK kinase inhibitors U0126 (U) and PD98059 (PD) and a PI3K inhibitor wortmannin (W) were able to block the stimulatory effects of bFGF on phosphorylated MAPK and PKB levels respectively. The participation of MAPK- and PI3K/PKB-signaling pathways in the regulation by bFGF of two well-known Sertoli cell-differentiated functions, lactate and transferrin production, was next explored. As for lactate production, PD and W did not modify the ability of bFGF to stimulate lactate production. However, a combination of PD and W partially impaired the increase in lactate production elicited by bFGF. The participation of MAPK- and PI3K/PKB-signaling pathways in the regulation by bFGF of glucose uptake and lactate dehydrogenase (LDH) activity was also analysed. In this respect, it was observed that W markedly decreased basal and bFGF-stimulated glucose uptake and that U and PD did not modify it. On the other hand, U and PD decreased the stimulation of LDH activity by bFGF whereas W did not modify it. As for transferrin production, while both MAPK kinase inhibitors partially decreased the ability of bFGF to stimulate transferrin secretion, the PI3K inhibitor did not modify it. In summary, the results demonstrated that bFGF stimulates MAPK- and PI3K/PKB-dependent pathways in rat Sertoli cells. Moreover, these results showed that while bFGF utilizes the MAPK pathway to regulate transferrin production and LDH activity, it uses the PI3K/PKB pathway to regulate glucose transport into the cell.

Regulation of rat Sertoli cell function by FSH: possible role of phosphatidylinositol 3-kinase/protein kinase B pathway.

The FSH molecular mechanism of action is best recognized for its stimulation of the adenylyl cyclase/cAMP pathway via activation of a G protein. Recently, links between cAMP, phosphatidylinositol 3-kinase (PI3K) and protein kinase B (PKB) signaling pathways in thyroid and granulosa cells have been observed. The aim of this study was to investigate the possible role of the PI3K/PKB pathway in FSH regulation of Sertoli cell function. Twenty-day-old rat Sertoli cell cultures were used. An increase in phosphorylated PKB (P-PKB) levels in response to FSH and dibutyryl-cAMP was observed. These increments in P-PKB levels were not observed in the presence of two PI3K inhibitors, wortmannin and Ly 294002. Inhibition of protein kinase A (PKA) by H89 did not decrease FSH stimulation of P-PKB levels. Taken together, these results indicate that FSH increases P-PKB levels in a PI3K-dependent and PKA-independent manner in rat Sertoli cells. In addition, wortmannin partially inhibited the ability of FSH to stimulate two well-known parameters of Sertoli cell function - transferrin secretion and lactate production - at doses equal to or lower than 0.1 microM. Related to lactate production, a decrease in FSH stimulation of lactate dehydrogenase activity and of basal and FSH-stimulated glucose uptake was observed in the presence of wortmannin. These metabolic changes were in most cases accompanied by changes in the levels of P-PKB. Altogether, these results suggest a meaningful role of the PI3K/PKB pathway in the mechanism of action of FSH in rat Sertoli cells.

Regulation of lactate production and glucose transport as well as of glucose transporter 1 and lactate dehydrogenase A mRNA levels by basic fibroblast growth factor in rat Sertoli cells.

By using cultured rat Sertoli cells as a model, both the action of basic fibroblast growth factor (bFGF) on lactate production and the site of this action were studied. bFGF stimulated Sertoli cell lactate production in a dose-dependent manner (basal: 7.3+/-0.5; 0.1 ng/ml bFGF: 7.5+/-0.5; 1 ng/ml bFGF: 7.5+/-0.6; 10 ng/ml bFGF: 10.3+/-1.0; 30 ng/ml bFGF: 15.2+/-1.5; 50 ng/ml bFGF: 15.4+/-1.6 microg/microg DNA). Two major sites for the action of this growth factor were identified. First, bFGF was shown to exert short- and long-term stimulatory effects on glucose transport (basal: 1170+/-102; 30 ng/ml bFGF for 120 min: 1718+/-152 and basal: 718+/-64; 30 ng/ml bFGF for 48 h: 1069+/-69 d.p.m./microg DNA respectively). Short-term bFGF stimulation of glucose transport was not inhibited by the protein synthesis inhibitor cycloheximide. These results indicate that short-term bFGF stimulation of glucose uptake does not involve an increase in the number of glucose transporters. On the other hand, stimulation with bFGF for periods of time longer than 12 h increased glucose transporter 1 (GLUT1) mRNA levels. These increased mRNA levels were probably ultimately responsible for the increments in glucose uptake that are observed in long-term treated cultures. Secondly, bFGF increased lactate dehydrogenase (LDH) activity (basal: 31.0+/-1.4; 30 ng/ml bFGF: 45.7+/- 2.4 mIU/microg DNA). The principal subunit component of those LDH isozymes that favors the transformation of pyruvate to lactate is subunit A. bFGF increased LDH A mRNA levels in a dose- and time-dependent manner. In summary, the results presented herein show that glucose transport, LDH activity and GLUT1 and LDH A mRNA levels are regulated by bFGF to achieve an increase in lactate production. These observed regulatory actions provide unequivocal evidence of the participation of bFGF in Sertoli cell lactate production which may be related to normal germ cell development.

National Human Exposure Assessment Survey: analysis of exposure pathways and routes for arsenic and lead in EPA Region 5.

The National Human Exposure Assessment Survey (NHEXAS) Phase I field study conducted in EPA Region 5 (Great Lakes Area) provides extensive exposure data on a representative sample of approximately 250 residents of the region. Associated environmental media and biomarker (blood, urine) concentration data were also obtained for the study participants to aid in understanding of the relationships of exposures to both contaminant pathways and doses. Besides fulfilling the primary NHEXAS objectives, the NHEXAS data provided an opportunity to explore secondary usages, such as examining pathway to route of exposure relationships. A generic type of structural equation model was used to define the anticipated relationships among the various data types for both arsenic (As) and lead (Pb). Since, by design, only a few participants provided data for all sample types, implementing this model required that some media concentrations (outdoor air and soil) be imputed for subjects with missing information by using measurements collected in the same geographic area and time period. The model, and associated pairwise correlations, generally revealed significant but weak associations among the concentrations, exposures, and doses; the strongest associations occurred for the various air measurements (indoor versus outdoor and personal). The generally weak associations were thought to be partly due to the absence of complete coverage of nonresidential environmental media and to nonsynchronization of relevant measurement times and integration periods of collection across the various sample types. In general, relationships between the NHEXAS questionnaire data and the various concentration, exposure, and body-burden measures were also weak. The model results and the modeling exercise suggest several ways for optimizing the design of future exposure assessment studies that are aimed at supporting structural modeling activities.

Contribution of children's activities to lead contamination of food.

This study evaluates the relationship of children's hygiene habits and food-handling behaviors on lead levels on hands and handled foods for toddlers living in lead-contaminated homes. Forty-eight inner city toddlers previously identified as having elevated blood lead levels participated in three consecutive days of designated food-handling activities. During the visits, duplicate diets were obtained, the child handled a banana, a hot dog, and had his/her hands wiped with a moist towelette. In addition, wipe samples were collected from the kitchen floor, and food items were deposited on and subsequently collected from the kitchen floor. All samples were analyzed for lead. The child's caregiver completed a questionnaire, which addressed the child's hygiene and eating behaviors. It was demonstrated that children's contact with residential dust containing lead can transfer lead to food. Both lead in the home and on the children's hands contribute to the contamination of food, and hence potential dietary exposure. Mean lead in handled bananas was 26 microg/kg and on hot dogs 65 microg/kg, and mean lead values on cheese and apple slices that had been on the floor were 119 and 215 microg/kg. In addition, the child's hygiene habits as reported by the parent indicate that lack of basic hygiene patterns within a high lead environment can contribute to children's dietary exposure to lead.

Smoking increases carcinogenic polycyclic aromatic hydrocarbons in human lung tissue.

Tobacco smoke is a major source of human exposure to polycyclic aromatic hydrocarbons (PAHs). The concentration of PAHs in lung tissue would reflect an individual's dose, and its variation could perhaps reflect cancer risk. Eleven PAHs were measured in 70 lung tissue samples from cancer-free autopsy donors by gas chromatography-mass spectrometry. There were 37 smokers and 33 nonsmokers as estimated by serum cotinine concentration. The sum of PAH concentrations was higher in smokers (P = 0.01), and there was a dose-response relationship for greater smoking (P < 0.01). Smoking increased the concentration of five PAHs including benzo(a)pyrene, which increased approximately 2-fold. The risk for increasing carcinogenic PAHs (odds ratio, 8.20; 95% confidence interval, 2.39-28.09) was 3-fold compared with noncarcinogenic PAHs (odds ratio, 2.61; 95% confidence interval, 0.75-9.12). A higher concentration of PAHs was detected in the lung tissue of males, although the estimated smoking was similar in males and females. Race was not associated with PAH concentrations overall, but PAH concentrations appeared to be higher in African-American males than in any other group. Age was weakly correlated with an increase in fluoranthene and pyrene. The measurement of PAHs in human lung tissue can be used to estimate the actual dose to the target organ.

Measurement of children's exposure to pesticides: analysis of urinary metabolite levels in a probability-based sample.

The Minnesota Children's Pesticide Exposure Study is a probability-based sample of 102 children 3-13 years old who were monitored for commonly used pesticides. During the summer of 1997, first-morning-void urine samples (1-3 per child) were obtained for 88% of study children and analyzed for metabolites of insecticides and herbicides: carbamates and related compounds (1-NAP), atrazine (AM), malathion (MDA), and chlorpyrifos and related compounds (TCPy). TCPy was present in 93% of the samples, whereas 1-NAP, MDA, and AM were detected in 45%, 37%, and 2% of samples, respectively. Measured intrachild means ranged from 1.4 microg/L for MDA to 9.2 microg/L for TCPy, and there was considerable intrachild variability. For children providing three urine samples, geometric mean TCPy levels were greater than the detection limit in 98% of the samples, and nearly half the children had geometric mean 1-NAP and MDA levels greater than the detection limit. Interchild variability was significantly greater than intrachild variability for 1-NAP (p = 0.0037) and TCPy (p < 0.0001). The four metabolites measured were not correlated within urine samples, and children's metabolite levels did not vary systematically by sex, age, race, household income, or putative household pesticide use. On a log scale, mean TCPy levels were significantly higher in urban than in nonurban children (7.2 vs. 4.7 microg/L; p = 0.036). Weighted population mean concentrations were 3.9 [standard error (SE) = 0.7; 95% confidence interval (CI), 2.5, 5.3] microg/L for 1-NAP, 1.7 (SE = 0.3; 95% CI, 1.1, 2.3) microg/L for MDA, and 9.6 (SE = 0.9; 95% CI, 7.8, 11) microg/L for TCPy. The weighted population results estimate the overall mean and variability of metabolite levels for more than 84,000 children in the census tracts sampled. Levels of 1-NAP were lower than reported adult reference range concentrations, whereas TCPy concentrations were substantially higher. Concentrations of MDA were detected more frequently and found at higher levels in children than in a recent nonprobability-based sample of adults. Overall, Minnesota children's TCPy and MDA levels were higher than in recent population-based studies of adults in the United States, but the relative magnitude of intraindividual variability was similar for adults and children.

An assessment of the data quality for NHEXAS--Part I: Exposure to metals and volatile organic chemicals in Region 5.

A National Human Exposure Assessment Survey (NHEXAS) was performed in U.S. Environmental Protection Agency (U.S. EPA) Region V, providing population-based exposure distribution data for metals and volatile organic chemicals (VOCs) in personal, indoor, and outdoor air, drinking water, beverages, food, dust, soil, blood, and urine. One of the principal objectives of NHEXAS was the testing of protocols for acquiring multimedia exposure measurements and developing databases for use in exposure models and assessments. Analysis of the data quality is one element in assessing the performance of the collection and analysis protocols used in NHEXAS. In addition, investigators must have data quality information available to guide their analyses of the study data. At the beginning of the program quality assurance (QA) goals were established for precision, accuracy, and method quantification limits. The assessment of data quality was complicated. First, quality control (QC) data were not available for all analytes and media sampled, because some of the QC data, e.g., precision of duplicate sample analysis, could be derived only if the analyte was present in the media sampled in at least four pairs of sample duplicates. Furthermore, several laboratories were responsible for the analysis of the collected samples. Each laboratory provided QC data according to their protocols and standard operating procedures (SOPs). Detection limits were established for each analyte in each sample type. The calculation of the method detection limits (MDLs) was different for each analytical method. The analytical methods for metals had adequate sensitivity for arsenic, lead, and cadmium in most media but not for chromium. The QA goals for arsenic and lead were met for all media except arsenic in dust and lead in air. The analytical methods for VOCs in air, water, and blood were sufficiently sensitive and met the QA goals, with very few exceptions. Accuracy was assessed as recovery from field controls. The results were excellent (> or = 98%) for metals in drinking water and acceptable (> or = 75%) for all VOCs except o-xylene in air. The recovery of VOCs from drinking water was lower, with all analytes except toluene (98%) in the 60-85% recovery range. The recovery of VOCs from drinking water also decreased when comparing holding times of < 8 and > 8 days. Assessment of the precision of sample collection and analysis was based on the percent relative standard deviation (% RSD) between the results for duplicate samples. In general, the number of duplicate samples (i.e., sample pairs) with measurable data were too few to assess the precision for cadmium and chromium in the various media. For arsenic and lead, the precision was excellent for indoor, and outdoor air (< 10% RSD) and, although not meeting QA goals, it was acceptable for arsenic in urine and lead in blood, but showed much higher variability in dust. There were no data available for metals in water and food to assess the precision of collection and analysis.

Regulation of lactate production by FSH, iL1beta, and TNFalpha in rat Sertoli cells.

One of the "nurse cell" functions of Sertoli cells is to provide lactate for the energy production in spermatocytes and spermatids. The present study shows that, as in porcine Sertoli cells, interleukin (IL)1beta and follicle-stimulating hormone (FSH) increase lactate production in rat Sertoli cells (basal, 9.1 +/- 1.0; FSH (100 ng/ml), 16.6 +/- 2.0; IL1beta (50 ng/ml), 13.3 +/- 1.6 microg/microg DNA). Increments in glucose uptake (basal, 1083 +/- 70; FSH, 2686 +/- 128; IL1beta, 1899 +/- 74 dpm/microg DNA), lactic dehydrogenase (LDH) activity (basal, 36.6 +/- 4.1; FSH, 52.2 +/- 4.9; IL1beta, 55.3 +/- 5.1 mUI/microg DNA), LDH A mRNA levels, and redistribution of LDH isozymes are involved in these stimulatory effects. Differences in the period required by IL1beta to increase glucose uptake, as compared with the porcine model, have been observed. In addition, tumor necrosis factor alpha (TNFalpha), one of the major stimulators for lactate production in porcine Sertoli cells, does not control the secretion of this glucose metabolite in rat Sertoli cells. Lactate production may be regulated differently among mammals.

Human FSH isoforms: carbohydrate complexity as determinant of in-vitro bioactivity.

Differences in sialic acid content of the hormone have been considered the main determinant of FSH polymorphism. The aim of the present study was to investigate the effect of variations in the oligosaccharide structure of the intrapituitary human FSH (hFSH) glycosylation variants on their intrinsic biological activity. FSH charge isoforms obtained after chromatofocusing were further separated by lectin affinity chromatography [Concanavalin A (ConA), Wheat germ agglutinin (WGA), Lentil lectin (LcH)]. Isolated isoforms were separately tested for in-vitro bioactivity in a rat Sertoli cell aromatization bioassay. Our results show that: (1) FSH microheterogeneity is due not only to variations in the sialic acid content of the hormone but also to differences in the internal structure of the carbohydrate chains, and (2) variations in the sialic acid content as well as differences in the complexity of the glycans determine the full biological expression of FSH glycosylation variants.

Particulate matter and manganese exposures in Indianapolis, Indiana.

The distribution of PM(2.5) and manganese (Mn) personal exposures was determined over a 4-month period in Indianapolis, IN, at a time when the gasoline additive, methylcyclopentadienyl manganese tricarbonyl (MMT), was not being used. The data collection period coincided with the data collection period in the Toronto, ON, study, where MMT had been used as a gasoline additive for over 20 years. The inferential or target population consisted of noninstitutionalized residents of the Indianapolis area during the monitoring period (from May 1996 through August 1996) who were at least 16 years old. The survey instruments used in this study (and also in Toronto) included a household screener form (HSF), a study questionnaire (SQ), and a time and activity questionnaire (TAQ). The SQ was administered to elicit information about the participant and his/her activities, occupation, and surroundings that might be relevant to his/her exposure to particles and Mn. In addition to the personal particulate matter (PM) and elemental 3-day monitoring, 240 participants completed a TAQ on a daily basis during the actual monitoring period. Also, a subset of participants had 3-day outdoor and indoor stationary monitoring at their home (approximately 58 observations), and sampling was conducted at a fixed site (approximately thirty-three 3-day observations). The quality of data was assessed and compared to the Toronto study in terms of linearity of measurement, instrument and method sensitivity, measurement biases, and measurement reproducibility. Twenty-six of the sample filters were subjected to two analyses to characterize the within-laboratory component of precision in terms of relative standard deviations (RSDs). The median RSD for Mn was 8.7%, as compared to 2.2% for Toronto. The quality assurance (QA) laboratory exhibited a clear positive bias relative to the primary laboratory for Al and Ca, but no systematic difference was evident for Mn. A high interlaboratory correlation (>0.99) was also attained for Mn. Mean field blank results for PM and Mn were 0.87 microg/m(3) and 0.71 ng/m(3), respectively, which were comparable to the Toronto study. The median RSDs for colocated fixed site and residential samples ranged from 2.2% to 9.0% for PM and from 8.8% to 15.3% for Mn, which were close to those observed in Toronto. For the PM(10), the 90th percentile indoors was 124 microg/m(3) compared with 54 microg/m(3) outdoors. This pattern was even more pronounced for the PM(2.5) data (90th percentiles of 92 microg/m(3) indoors vs 30 microg/m(3) outdoors). Personal PM(2.5) was somewhat higher than the indoor levels, but the percentiles seemed to follow the more highly skewed pattern of the indoor distribution. This difference was largely due to the presence of some smokers in the sample; e.g., exclusion of smokers led to a personal exposure distribution that was more similar to the outdoor distribution. The estimated 90th percentile for the nonsmokers' personal exposures to PM was 43 microg/m(3) compared with 84 microg/m(3) for the overall population. In general, the Indianapolis PM levels of a given type and cut size were somewhat higher than the levels observed in Toronto, e.g., the median and 90th percentile for the personal PM(2.5) exposures were 23 and 85 microg/m(3), respectively, in Indianapolis, while in Toronto, the corresponding percentiles were 19 and 63 microg/m(3). The cities' distributions of the proportion of the PM(10) mass in the 2.5-microm fraction appeared similar for the residential outdoor data (medians of 0.67 and 0.65 for Indianapolis and Toronto, respectively, and 90th percentiles of 0.83 for both cities). For the indoor data, Indianapolis tended to have a larger portion of the mass in the fine fraction (median of 0.80 compared to 0.70 for Toronto). Unlike the PM, the Indianapolis indoor Mn concentration levels were substantially lower than the outdoor levels for both PM sizes, and the median personal levels for Mn in PM(2.5) appeared to fall between the median indoor and outdoor levels. The personal Mn exposure distributions exhibited more skewness than the indoor or outdoor distributions (e.g., the means for the personal, indoor, and outdoor distributions were 7.5, 2.6, and 3.5 ng/m(3), respectively, while the medians were 2.8, 2.2, and 3.2 ng/m(3), respectively). At least a substantial portion of the high end of the personal exposure distribution appeared to be associated with occupational exposures to Mn. In general, the Mn levels in both cut sizes in Indianapolis were approximately 5 ng/m(3) smaller than those in Toronto (e.g., the estimated median and mean levels for personal Mn exposures in PM(2.5) were 2.8 and 7.5 ng/m(3), respectively, in Indianapolis, but were 8.0 and 13.1 ng/m(3) in Toronto). For the nonoccupational subgroups with no exposure to smoking and no subway riders in the two cities, the medians (2.6 ng/m(3) in Indianapolis and 7.8 ng/m(3) in Toronto) were similar to those for the overall populations, but the means were substantially smaller (3.1 ng/m(3) in Indianapolis and 9.2 ng/m(3) in Toronto). The median proportion of Mn in the fine fraction (relative to the PM(10) Mn) for Indianapolis was 0.39 for outdoors and 0.55 for indoors; these ratios were somewhat smaller than the corresponding Toronto medians (0.52 and 0.73). The study found high correlations for particulates and Mn between personal exposures and indoor concentrations, and between outdoor and fixed site concentrations, and low correlations of personal and indoor levels with outdoor and fixed site levels. The pattern was similar to that observed for Toronto, but slightly more pronounced. The PM(10) Mn concentrations (log scale) generally exhibited stronger associations among these various measures than the PM(2.5) Mn concentrations. Comparisons of the particulate distributions between PTEAM (Riverside, CA) and the Indianapolis and Toronto studies were also made.