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Background and aim:Basic fibroblast growth factor (bFGF) and interleukin 1β (IL1β) 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 IL1β 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 IL1β 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 IL1 β on phosphorylated CREB. A possible correlation between CREB regulation and two Sertoli cell-differentiated functions, Ldh Aand transferrin expression, was explored. PD98059 blocked the ability of bFGF to stimulate Ldh Aexpression and SB203580 blocked the ability of IL1 β to stimulate Ldh Aexpression and LDH activity. Concerning transferrin, PD98059 and U0126 were able to inhibit the ability of bFGF to stimulate its secretion. On the contrary, SB203580 was unable to block IL1β 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 IL1 β through p42/p44-MAPK and p38-MAPK pathways and that this transcription factor may be partially responsible for the regulation of Sertoli cell function.

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.Journal of Exposure Analysis and Environmental Epidemiology (2002) 12, 29–43 10.1038/sj/jea/7500198

The National Human Exposure Assessment Survey (NHEXAS)/Minnesota Children's Pesticide Exposure Study (MNCPES) was a population-based study designed to characterize children's exposure to residential pesticides and to evaluate the contribution of residential and children's activities to children's exposure. Families of 168 children were surveyed for residential use of pesticides and children's activities. From these homes, families of 102 children between the ages of 3 and 13 years participated in a week-long intensive exposure study. Of the 102 children, 19 children were videotaped for four consecutive hours in their normal daily activities. The survey responses indicated that the youngest children were more likely to exhibit behaviors that would foster exposure to environmental contaminants. Comparison of questionnaire responses indicated that the videotaped subsample was representative of the exposure study population. The microactivities of the videotaped children that might contribute to their exposure via ingestion or dermal routes were quantified. Hand-to-mouth and object-to-mouth activities were observed most frequently among the youngest children. The youngest children were also most likely to be barefoot both indoors and outside. Gender differences were found in mouthing behavior and the proportion of observed time spent outdoors.Journal of Exposure Analysis and Environmental Epidemiology (2001) 11, 501–509. 10.1038/sj.jea.7500193

The distribution of PM2.5and 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 μg/m3and 0.71 ng/m3, 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 PM10, the 90th percentile indoors was 124 μg/m3compared with 54 μg/m3outdoors. This pattern was even more pronounced for the PM2.5data (90th percentiles of 92 μg/m3indoors vs 30 μg/m3outdoors). Personal PM2.5was 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 μg/m3compared with 84 μg/m3for 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 PM2.5exposures were 23 and 85 μg/m3, respectively, in Indianapolis, while in Toronto, the corresponding percentiles were 19 and 63 μg/m3. The cities' distributions of the proportion of the PM10mass in the 2.5-μm 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 PM2.5appeared 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/m3, respectively, while the medians were 2.8, 2.2, and 3.2 ng/m3, 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/m3smaller than those in Toronto (e.g., the estimated median and mean levels for personal Mn exposures in PM2.5were 2.8 and 7.5 ng/m3, respectively, in Indianapolis, but were 8.0 and 13.1 ng/m3in Toronto). For the nonoccupational subgroups with no exposure to smoking and no subway riders in the two cities, the medians (2.6 ng/m3in Indianapolis and 7.8 ng/m3in Toronto) were similar to those for the overall populations, but the means were substantially smaller (3.1 ng/m3in Indianapolis and 9.2 ng/m3in Toronto). The median proportion of Mn in the fine fraction (relative to the PM10Mn) 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 PM10Mn concentrations (log scale) generally exhibited stronger associations among these various measures than the PM2.5Mn concentrations. Comparisons of the particulate distributions between PTEAM (Riverside, CA) and the Indianapolis and Toronto studies were also made.Journal of Exposure Analysis and Environmental Epidemiology (2001) 11, 423–440. 10.1038/sj.jea.7500186

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)1β 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; IL1β (50 ng/ml), 13.3 ± 1.6 μg/μg DNA). Increments in glucose uptake (basal, 1083 ± 70; FSH, 2686 ± 128; IL1β, 1899 ± 74 dpm/μg DNA), lactic dehydrogenase (LDH) activity (basal, 36.6 ± 4.1; FSH, 52.2 ± 4.9; IL1β, 55.3 ± 5.1 mUI/μg DNA), LDH A mRNA levels, and redistribution of LDH isozymes are involved in these stimulatory effects. Differences in the period required by IL1β to increase glucose uptake, as compared with the porcine model, have been observed. In addition, tumor necrosis factor α (TNFα), 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.

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 (≥98%) for metals in drinking water and acceptable (≥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.Journal of Exposure Analysis and Environmental Epidemiology (2001) 11, 140–154. 10.1038/sj.jea.7500157

To estimate pesticide exposure, urine samples are often needed to analyze pesticide metabolites. However, this is difficult for children wearing diapers because simple and feasible techniques suitable for field collection are not available. The objectives of this study were to test the validity of using cotton gauze pad as a medium for collecting urine samples from young children and to examine the stability of the recoveries for creatinine and pesticide metabolites over 24 h. Urine spiked with a pesticide and four metabolites, 2,4-dichlorophenoxyacetic acid (which is mainly eliminated from urine unchanged), 3-phenoxybenzoic acid (metabolite for synthetic pyrethroids), atrazine mercapturate (metabolite for atrazine), malathion dicarboxylic acid (metabolite for malathion), and 2-isopropyl-4-methyl-6-hydroxypyrimidine (metabolite for diazinon) was added to the gauze pads and kept in jars at 37°C in a water bath. Urine was expressed from the gauze pads immediately and after 1, 2, 4, 8, and 24 h, then analyzed. The recoveries, calculated as the percentage of concentration in expressed urine divided by that of the control urine sample, were within a range of 70–130%. The metabolite and creatinine concentrations did not change with time in either expressed urine samples or controls. The results suggest that cotton gauze pad is a promising candidate for collecting urine samples from young children wearing diapers for studies in which these five urinary pesticide metabolites are to be analyzed.Journal of Exposure Analysis and Environmental Epidemiology (2000) 10, 703–709. 10.1038/sj.jea.7500134

A deterministic model was developed to identify the critical input parameters needed to assess dietary intakes of young children. The model was used as a framework for understanding the important factors in data collection and data analysis. Factors incorporated into the model included transfer efficiencies of pesticide from surfaces to food, transfer efficiencies of pesticide from surfaces to hands to food, and more accurate microactivity data related to contact frequency for the three variables of interest — hands, surfaces, and food. Results from range-finding measurements of transfer efficiencies using an aqueous pesticide solution of a mixture of malathion, diazinon, and chlorpyrifos sprayed on the surfaces indicate that a higher pesticide transfer occurred from hard surfaces to food (hardwood, plastic), with low transfer from soft surfaces (carpet, cloth). Six children, all less than 4 years old, were videotaped to obtain realistic contact frequency and times for the interaction of hands, surfaces, and foods during eating meals and snacks while in their homes or day care centers. The time range of eating events varied from about 2 to 55 min, with an average of about 20 min. The average number of contact frequencies between food and hands was 19 times for each eating event, with a range of 10–40. Contacts between the surface and hand were about the same as the food and hands. Contacts between foods and surfaces ranged from 0 to 32, but only five or less of the contacts per eating event were associated with surfaces other than eating utensil. The children's microactivity data collected during the eating events, together with the laboratory results from the transfer studies, were provided as input into a Monte Carlo simulation of the dietary ingestion model. Simulation results indicate that children's handling of the food could contribute 20–80% of the total dietary intake of pesticides. Dietary exposure due to residues in the food before handling accounted for 16% and 47%, respectively, of the total mean intake from simulations for a child's consumption of an apple or banana. These results indicated that transfer efficiencies for foods on various surfaces typically found in homes as well as children's hand contacts with the food and surfaces are important as determinants of dietary exposure.Journal of Exposure Analysis and Environmental Epidemiology (2000) 10, 710–722. 10.1038/sj.jea.7500129

During the Minnesota Children's Pesticide Exposure Study (MNCPES), comparisons were made between the insecticide/herbicide loadings obtained with two household dust/insecticide or herbicide samplers: the Edwards and Lioy (EL) press sampler (used for dust collection from carpets or other surfaces) and the Lioy, Wainman and Weisel (LWW) surface wipe sampler. The results were compared with hand rinse levels, and urine metabolite levels obtained from 102 children (ages 3–13). All measurements were made during a 1-week sampling period, and information was obtained on household pesticide use and each child's activities. Of the homes, <5% had recent spot uses of a pesticide but none had recent general applications. The analyses focused primarily on atrazine (a herbicide), and malathion, diazinon, and chlorpyrifos (insecticides). Metabolites were measured for atrazine, malathion and chlorpyrifos. The atrazine levels obtained using the EL indicate that this compound was transported into the home by an unquantified transport mechanism (e.g. tracking of soil). Two malathion hand rinse values exceeded >170 ng/cm2, suggesting that since indoor surface levels were low, these children had other sources of exposure. Atrazine, chlorpyrifos and malathion were detectable in >30% of the homes by the EL, LWW or hand rinse. Only chlorpyrifos had detectable levels in ≥50% of the samples for all types, i.e. compound or metabolite, which is consistent with it being a common household pesticide. The median (and maximum) chlorpyrifos levels for the EL surface, EL carpet, LWW surface (two rooms), hand rinse, and urine metabolites were: 0.07 (32.6) ng/cm2; 0.07 (44.5) ng/cm2; 0.34 (3.64) ng/cm2; 0.42 (14.4) ng/cm2; 0.03 (2.14) ng/hand and 6.9 (59.0) µg/g, respectively. A strong correlation was found for chlorpyrifos between the EL surface and carpet samples. Chlorpyrifos levels detected by LWW had a different distribution and concentration range than the EL, indicating that it collected more than the surface dislodgeable insecticide. EL was directly comparable to the hand rinse or urine levels, but only the LWW had a weak correlation with hand rinse levels, suggesting that the children had other sources of chlorpyrifos exposure. Thus, mechanistic exposure studies are needed to more accurately establish exposure–dose relationships in residential settings.Journal of Exposure Analysis and Environmental Epidemiology (2000) 10, 327–340. 10.1038/sj.jea.7500099

For the Phase I field test of the National Human Exposure Assessment Survey (NHEXAS) in U.S. Environmental Protection Agency (EPA) Region 5, this paper presents the survey sampling design, the response rates achieved, and the sample weighting procedure implemented to compensate for unit nonresponse. To enable statistically defensible inferences to the entire region, a sample of about 250 members of the household population in EPA Region 5 was selected using a stratified multistage probability-based survey sampling design. Sample selection proceeded in four nested stages: (1) sample counties; (2) area segments based on Census blocks within sample counties; (3) housing units (HUs) within sample segments; and (4) individual participants within sample households. Each fourth-stage sample member was asked to participate in 6 days of exposure monitoring. A subsample of participants was asked to participate in two rounds of longitudinal follow-up data collection. Approximately 70% of all sample households participated in household screening interviews in which rosters of household members were developed. Over 70% of the sample subjects selected from these households completed the Baseline Questionnaire regarding their demographic characteristics and potential for exposures. And, over 75% of these sample members went on to complete at least the core environmental monitoring, including personal exposures to volatile organic compounds (VOCs) and tap water concentrations of metals. The sample weighting procedures used the data collected in the screening interviews for all household members to fit logistic models for nonresponse in the later phases of the study. Moreover, the statistical analysis weights were poststratified to 1994 State population projections obtained from the Bureau of the Census to ensure consistency with other statistics for the Region.Journal of Exposure Analysis and Environmental Epidemiology (1999) 9, 369–380. 10.1038/sj.jea.7500054

The National Human Exposure Assessment Survey (NHEXAS) Phase I field study conducted in EPA Region 5 provides extensive exposure data on approximately 250 study participants selected via probability sampling. Associated environmental media and biomarker (blood, urine) concentration data were also obtained to aid in the understanding of relationships of the exposures to both contaminant sources and doses. Distributional parameters for arsenic (As), lead (Pb), and four volatile organic compounds (VOCs)—benzene, chloroform, tetrachloroethylene, and trichloroethylene—were estimated for each of the relevant media using weighted data analysis techniques. Inter-media associations were investigated through correlation analysis, and longitudinal correlations and models were used to investigate longitudinal patterns. Solid food appeared to be a major contributor to urine As levels, while Pb levels in household (HH) dust, personal air, and beverages all were significantly associated with blood Pb levels. Relatively high (>0.50) longitudinal correlations were observed for tap water Pb and As, as compared to only moderate longitudinal correlations for the personal air VOCs.Journal of Exposure Analysis and Environmental Epidemiology (1999) 9, 381–392. 10.1038/sj.jea.7500055

The National Human Exposure Assessment Survey (NHEXAS) provides a rich database of exposure and environmental measurements for persons living in EPA Region V (Great Lakes). Demographics (e.g., gender, minority status, age, income, and year home built) between U.S. Census data and the overall Region V sample were compared and showed good agreement. This representative sample was used to conduct an exploratory investigation of selected subpopulations that might exhibit higher exposures, on average, to volatile organic chemicals (VOCs) such as benzene, chloroform, etc.; inspirable particles; and metals (e.g., lead, arsenic, etc.) than the general population in Region V. Means and medians were the metrics of comparison. Personal air exposures for p-dichlorobenzene were significantly higher in adults (>21 years old) than in children (1–14 years old) (median: below detection limit vs. 0.87 μg/m3, p=0.0005), while a trend toward higher levels of arsenic exposure in children than adults was observed (median: 1.13 vs. 0.8 ng/m3, p=0.083). A trend towards higher personal air exposure to lead for minorities vs. nonminorities was evident (median: 26 vs. 12 ng/m3, p=0.066), but personal exposure to 1,1,1-trichloroethane tended to be higher in nonminorities (mean: 22 vs. 3.7 μg/m3, p=0.081). Dietary exposure to arsenic from solid foods was significantly higher in adults than children (mean: 21 vs. 7.1 μg/kg, p=0.0001; median: 10 vs. 5.6 μg/kg, p=<0.001), and for cadmium it was higher for nonminorities than minorities (median: 18 vs. 15 μg/kg, p=0.023). In contrast, the dietary intake for arsenic, which is based on body weight, was significantly higher in children than adults (mean: 1.72 vs 1.38 μg kg−1day−1, p=<0.0001; median 1.02 vs. 0.83, p=<0.0001). Dietary exposure to chromium in beverages tended to be higher in minorities than nonminorities (median: 16 vs. 13 μg/kg, p=0.017). Lead levels in surface dust wipes tended to increase with the age of the home (mean: 128 μg/g in homes built since 1980 to 1075 μg/g in homes built before 1940; median: 93 to 236 μg/g, respectively). These findings were consistent with the observation that for persons living in older homes personal air exposures to lead are elevated compared to persons living in recently built homes (median: 12 ng/m3in homes built since 1980, vs. 24 ng/m3in homes built before 1940, p=0.043).Journal of Exposure Analysis and Environmental Epidemiology (1999) 9, 49–55. 10.1038/sj.jea.7500025

A scoping study, the National Human Exposure Assessment Survey (NHEXAS) was conducted in EPA Region V from July 1995 to May 1997. This probability-based population study provided an opportunity to examine the mercury levels in 182 participants who provided hair samples. A sensitive analytical procedure based on atomic fluorescence spectrometry was developed and evaluated for the analysis of Hg in approximately 5 mg of human hair. The correlation coefficient (r), the precision, and bias were 0.9983, ≤1.6%, and ≤8%, respectively, for standard curves in the hair matrix. The method detection limit (MDL), recovery of Hg in a certified sample (NIES-13), precision (% RSD) for duplicate extract analysis, and precision for duplicate sample analysis averaged 12 ppb (range 4 to 22 ppb), 100±3% (N=27), 4.6±2.8 (N=18), and 12.5±7.4 (N=17), respectively, over the 7 to 8 months of sample analysis. The low MDL yielded 95% of the samples with measurable values, permitting the entire distribution of Hg levels to be characterized. Comparison of annualized Hg distribution in hair with and without background correction revealed a negligible bias on the distribution (1.47% at the 90th percentile). Also, a comparison of the unweighted and nonannualized weighted Hg levels throughout the percentile distribution indicated a small deviation in the upper tail (95th percentile) and is attributable to the small sample size (N=182). The mean, median, and maximum of the annualized Hg levels in hair were 287, 204, and 3505 ppb, respectively. The 75th percentiles were 335 and 368 ppb for the weighted annualized and unweighted distributions, respectively. The percent of individuals in three age categories (0–24, 25–49, and 50 years and older) who exceeded the 75th percentile showed a linear increase with age. Males (N=81) had 10% and 20% lower mean levels than females (N=101) for unweighted and annualized weighted Hg data, respectively. The application of this methodology for characterizing hair Hg levels in fish-eating populations is discussed.Journal of Exposure Analysis and Environmental Epidemiology (1999) 9, 393–401. 10.1038/sj.jea.7500056

The design and application of a two dimensional gas-liquid chromatograph (gc) to the analysis of clofibrate in rabbit plasma is described. The assay involves three steps: extraction of plasma, derivatization with pentafluorobenzylbromide and dual gc analysis. Development time for an assay for drugs is considerably shortened as compared to conventional approaches using other chromatographic methods. Approximately 20 samples can be processed in a day.

The United States Environmental Protection Agency (U.S. EPA) requires reference spectra to support its gas chromatography/Fourier transform infrared (GC/FT-IR) routine environmental monitoring program. Although on-the-fly (OTF) techniques are needed to satisfy the Agency's high sample throughput requirements, the FT-IR vapor-phase reference spectra produced by the Agency thus far have been measured under static conditions. Accordingly, the OTF spectra of 47 environmentally important compounds have been measured by packed-column GC/FT-IR under carefully controlled conditions. The compounds selected for spectral measurement are currently regulated by the U.S. EPA and generally represent compound classes which are absent, or poorly represented, in the current U.S. EPA data base (e.g., organochlorine and organophosphorus pesticides). Where feasible, the Co-blentz Society guidelines for the measurement and recording of vapor-phase infrared reference spectra and supporting data were followed. The sensitivity order of the reference compounds as determined by the strongest spectral band and the quantity of compound injected on-column was, organophosphorus and thio-organophosphorous > aliphatic organochlorine ≥ polynuclear aromatic.

Mature Leydig cells, the main source of testicular testosterone in mammals, arise from immature mesenchymal precursors through an LH-dependent differentiation process. In order to study the steroidogenic potential of these precursors, undifferentiated mesenchymal cells were obtained from the testicular interstitium of two patients with androgen insensitivity syndrome. After double digestion with collagenase and separation of the suspensions in a Percoll density gradient, the cells were cultured in Ham’s F12 medium: Dulbecco’s Modified Eagle Medium (1:1) supplemented with antibiotics, transferrin, insulin, hydrocortisone, and vitamin E with or without 1 IU of hCG/ml. At 11 days in culture, samples were removed for morphological characterization and determination of 3β-hydroxysteroid dehydrogenase activity (3β-HSD). Testosterone concentration was determined by RIA in the culture medium at different intervals. Cultured cells were mesenchymal in appearance, elongated in shape, with numerous processes running in different directions. No mature Leydig cells were present. In basal conditions, the percentages of 3β-HSD-positive cells at 11 days on patients 1 and 2 were 33% and 28%, respectively, and the testosterone concentrations in the culture media were 4.8 and 8.4 ng.106cells.24 h, respectively. In cultures stimulated with hCG, there was an increase of histochemical reactivity (47% and 42% in patients 1 and 2, respectively) and in the amount of testosterone secreted (10.2 and 12.0 ng.106cells, respectively). Electron microscopic studies of cultures grown in the absence of hCG demonstrated a homogenous population of poorly differentiated, fibroblastic-type mesenchymal cells. Cultures stimulated with hCG for 11 days showed a marked increase in organelles, particularly the number of mitochondria and smooth endoplasmic reticulum cisternae, which adopted a pattern resembling the one classically associated with steroid secretion. We report here a successful culture of human testicular mesenchymal cells, demonstrating that immature Leydig precursors are capable of testosterone synthesis and secretion and should, therefore, be included in the family of testosterone-producing cells. Addition of hCG increases testosterone secretion and promotes a trophic effect, triggering early cytologic differentiation toward mature Leydig cells.

The formation of N-nitrosodimethylamine (DMN) from dimethylamine (DMA) in the presence of ozone, NOx, NO, NO2 and humidity was evaluated for the sorbent, Tenax GC under conditions relevant to field sampling. Traces (<30 ppt) of DMN were formed from DMA when using a sampling cartridge containing Tenax GC held by glass wool plugs preceded by a glass fiber filter and high atmospheric concentrations of NO, NO2 and O3. However, the trace levels of DMN do not hamper the use of the Tenax GC cartridge sampler for ambient air sampling.

N-Nitrosodimethylamine (DMN) levels in ambient air were determined for an area surrounding an industrial site in Baltimore, MD. Using a Tenax GC cartridge for concentrating DMN and glass capillary gas-liquid chromatography/mass spectrometry with specific ion (m/e 74) monitoring, DMN was quantified. The limit of detection was ca. 0.3 ppt at 25°C. On the industrial site DMN levels reached 32,000 ng/m3 (10.67 ppb) of ambient air.

The performances of several sorbents as collection media for the quantitative concentration and analysis of volatile, hazardous, vapor-phase compounds from ambient atmospheres were evaluated under a variety of conditions relevant to field sampling. Tenax GC was found to be superior to other sorbents in most cases. The effects of humidity, background air pollution, repeated re-use of sorbent, and transportation and storage of collected samples were investigated.

γ‐Glutamyl transpeptidase (γ‐GTP) activity in Sertoli cells can be stimulated by FSH. This cAMP‐dependent metabolic event can be enhanced when Sertoli cells are co‐cultured with germ cells, suggesting that different signal transduction pathways may be involved in the regulation of γ‐GTP activity. In this study we examined the participation of Ca2+‐ and protein kinase C (pkC)‐dependent signal transduction pathways in the regulation of basal and FSH‐stimulated γ‐GTP activity. Under basal conditions, the increase in extracellular Ca2+concentration or the addition of the Ca2+ionophore 4Br‐A23187 produced a decrease in γ‐GTP activity. Conversely, blockage of voltage‐dependent Ca2+channels with verapamil or nifedipine or inhibition of Ca2+‐calmodulin dependent processes with trifluoperazine resulted in an increase in γ‐GTP activity. To study the role of a pkC‐dependent pathway the effects of low doses of staurosporine were evaluated. Under these experimental conditions an increase in γ‐GTP activity was observed. It was then investigated whether these signal transduction pathways could interact with the FSH‐stimulated cAMP‐dependent pathway to regulate γ‐GTP activity. Increase in extracellular Ca2+concentration, the addition of 4Br‐A23187 or the blockage of voltage‐dependent Ca2+channels did not modify FSH‐stimulated γ‐GTP activity. However, staurosporine produced an additional increase in FSH‐stimulated γ‐GTP activity and this effect was also observed when cells were stimulated with dbcAMP. In summary, our data are consistent with an inhibitory role of Ca2+‐calmodulin‐ and pkC‐dependent pathways in the regulation of basal γ‐GTP activity. Similar to what has been shown for other Sertoli cell parameters, a pkC‐dependent pathway can interact with the FSH‐stimulated cAMP‐dependent pathway. The precise steps involved in this interaction are still unknown.

Organic vapors in ambient air, at or near an industrial site in Baltimore, Maryland, were collected by adsorption on a sorbent of porous polymer (Tenax GC, 35/60). The pollutants were recovered by thermal desorption and analyzed by gas-liquid chromatography mass spectrometry computer using capillary glass SCOT columns. N-Nitrosodimethylamine was identified from its mass spectrum as a constituent of the atmosphere in the areas sampled. The identification of this compound was confirmed by comparison of its mass spectrum with that of authentic N-nitrosodimethylamine; identical retention times of unknown and authentic compound on three different capillary columns were observed.

Pyrolysis coupled with gas chromatography and carbon dioxide supercritical fluid extraction/supercritical fluid chromatography was used to study the affect of pyrolysis temperature (500 or 999°C) and pyrolysis atmosphere (helium or carbon dioxide) on the resulting chromatographic profiles of asphaltenes. The use of the lower pyrolysis temperature yielded fewer and less volatile components than did the high pyrolysis temperature. This was supported by both gas chromatographic profiles and the profiles obtained after supercritical fluid extraction and chromatography. Fast atom bombardment/Mass spectrometry (FAB/MS) and Fourier Transform Infrared Spectrophotometric (FTIR) studies revealed, for these experiments, that although the pyrolysis process greatly altered the structure of the asphaltenes, the effect of the atmosphere present during pyrolysis appeared to have little affect on the fragments formed when these reactions were carried out at ambient pressure.

Experiments in partially eviscerated dogs failed to provide evidence that growth hormone stimulates glucagon secretion. The results suggest that the rise in plasma glucagon level observed in a variety of experimental conditions may have been caused by surgical trauma, perhaps resulting in changes in the blood supply or in the autonomic impulses to the pancreas.

Among the cause of male pseudohermafroditism(MPH), disorders of testicular function, which include enzymatic defects in the testosterone (T)biosynthesis, have been demonstrated. In a 8 1/2 years old patient with MPH (MG, 46 XY), with ambiguous genitalia and raised as a female, plasmatic levels of the following steroids were determined: Pregnenolone (P5), Progesterone (P4), Androstenedione (Δ 4), 17αhydroxyprogesterone (17αOHP4) and T. Values were found in the normal prepubertal range. Lack of response to acute hCG stimulation for these steroids was observed. After gonadectomy, Leydig cell mesenchymal precursors were isolated as previously described (Biol.Reprod.46:793, 1992). Cells were cultured for 6 days and T,P5,P4 17OHP4, Δ4 and dehydroepiandrosterone (DHA) levels were determined by RIA in the culture medium. Results were compared with those found in two other patients (PM, VT) bearing the androgen insensitivity syndrome. Levels of T (pg/h/ugDNA) were as follows, MG:0.35±0.06, PM:101±10 and VT: 141±15. Similar results in FSH or hCG stimulated cultures were obtained. The overall steroid production in the three patients was: MG: 108, PM; 184 and VT: 319 (pg/h/ugDNA). A marked modification of T/Δ 4 relationship was observed in MG (MG: 0.03, PM: 64 and VT: 3.97). These results suggest that MG male pseudohermafroditism is due to 17β hydroxysteroid dehydrogenase deficiency. This deficiency could not be demonstrated at the peripheral level but it was evident in Leydig cell mesenchymal precursors in culture.

A FORTRAN IV computer program has been developed for calibrating columns for quantification of biological compounds by gas-liquid chromatography. This technique has been utilized to determine the degree that column variability may affect the slope of standard curves for amino acid derivatives. The FORTRAN IV Program tabulates input data such as peak height and width and calculates peak area and the relative response ratio. In addition, the mean, standard deviation and standard error for the relative response ratio at each concentration are determined, and linear regression constants for each set of ratios are calculated by the least squares method. The 95% confidence limits are also computed and two x-y points are requested in the computer computations for each regression line. The slopes of standard curves for amino acids were found to vary significantly for GLC columns packed with stationary phase coated on solid support from the same or different preparation batches. The maximum error which was observed to occur by using a single set of theoretical curves prepared from one column for quantification of amino acids on four columns was 268% (threonine). If comparable results are to be obtained in accurate analyses incolving more than one column, it is necessary to precisely calibrate each column.