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Aim: The aim of this paper is to evaluate biomaterial cues combined with physical therapy (PT) on functional recovery in a rat sciatic nerve injury model. Materials & methods: Nerve growth conduits were filled with longitudinally aligned hyaluronic acid fibers and microspheres containing neurotrophic factor (growth factor [GF]). All animals received behavior and functional testing throughout the study, which concluded with measurement of compound muscle action potentials and contractile force of the gastrocnemius muscle. Results & conclusion: Including GF improved recovery of gross motor function and increased sensory pain sensation. During the 4 weeks that animals participated in PT, these groups showed higher static sciatic index scores. Including GF and PT has the potential to improve clinical outcomes following peripheral nerve injury.

Anthropogenic emissions have altered the N status of forests in the northeastern United States, highlighting the importance of our imperfect understanding of the interaction between nitrogen (N) and phosphorus (P) in response to atmospheric N deposition. We investigated soil N and P dynamics at the Bear Brook Watershed in Maine (BBWM), a long-term paired watershed experiment established to study ecosystem response to experimental N enrichment. One watershed (West Bear [WB]) was treated bimonthly for 25 yr with ammonium sulfate, and the reference East Bear (EB) received only ambient N deposition. We conducted field and laboratory studies to examine the interaction between N and P in O horizon soils in both EB and WB. In the “Field Addition” study, an addition of 100 kg P ha⁻¹ resulted in an overall 38% decrease in extractable ammonium (NH₄⁺–N) due to increased immobilization. Even under ambient N deposition rates, EB displayed parallel, although lower, evidence of P limitation compared with WB. In contrast, in the “Laboratory Addition” study, soils incubated in the laboratory at rates of 0 to 200 kg P ha⁻¹ showed increases in potential net N mineralization (PNNM) and NH₄⁺–N concentrations in response to P additions. There was no effect of N status in the Laboratory Addition study, but hardwood soils showed a faster response and greater rates of PNNM compared with softwood soils. Despite contrasting responses, both the field and laboratory studies suggested that N dynamics at BBWM were P limited and that N status and forest type influenced the N and P interaction.

The vernal transition represents the seasonal transition to spring, occurring as temperatures rise at the end of winter. With rapid snowmelt, microbial community turnover, and accelerated nutrient cycling, this is a critical but relatively under-studied period of ecosystem function. We conducted a study over two consecutive winters (2015-2016) at the Bear Brook Watershed in Maine to examine how changing winter conditions (warming winters, reduced snow accumulation) altered soil nitrogen availability and stream N export during winter and the vernal transition, and how these patterns were influenced by ecosystem N status (N-enriched vs. N-limited). Of the two study years, 2016 had a warmer winter with substantially less snow accumulation and a discontinuous snowpack-and as a result, had a longer vernal transition and a snowpack that thawed before the vernal transition began. Across both years, snowmelt triggered a transition, signaled by increased ammonium concentrations in soil, decreased soil nitrate concentrations due to flushing by meltwater, and increased stream nitrate exports. Despite the contrasting winter conditions, both years showed similar patterns in N availability and export, differing only in the timing of these transitions. The vernal transition has conventionally been considered a critical period for biogeochemical cycling, because the associated snowmelt event triggers physicochemical and biochemical changes in soil systems. This was consistent with our results in 2015, but our data for 2016 show that this may not always hold true, and instead, that warmer, low-snow winters may demonstrate a temporal asynchrony between snowmelt and the vernal transition. We also show that ecosystem N status is a strong driver of the seasonal N pattern, and the interaction of N status and changing climate must be further investigated to understand ecosystem function under our current predicted trajectory of warming winters, declining snowfall, and winter thaw events.

Plastic revolutionized the industry during its invention. It helps us not only to have strong and flexible tools but also to have cheaper materials for almost everything we make. Despite of its usefulness, it also has diverse effects in our ecosystem. Hazardous chemicals leaking from landfilled plastics runs through rivers and lakes which are primary sources of water. Aquatic animal suspect plastics as foods which make them feel full all the time without nutrients coming from their body and causes them to die in hunger and the birth of "Micro plastic" pollution in the environment. Those are some of negative effects of plastics in our environment which is critical for our future generations. The researchers introduces a biodegradable packaging bag that focuses on creating a product to be used as alternative to plastics and solve the negative effects of plastics that affect environment through the use of safe and bio-degradable materials such as natural starch from cassava, glycerol, and many more. By mixing the right proportions of the main materials and perfect amount of heat, the researchers achieved the best features of the bio-degradable polymer that will be discussed later in this paper.

Background Exosomes are extracellular vesicles containing a variety of biological molecules including microRNAs (miRNAs). We have recently demonstrated that certain miRNA species are selectively and highly enriched in pancreatic cancer exosomes with miR-1246 being the most abundant. Exosome miRNAs have been shown to mediate intercellular communication in the tumor microenvironment and promote cancer progression. Therefore, understanding how exosomes selectively enrich specific miRNAs to initiate exosome miRNA signaling in cancer cells is critical to advancing cancer exosome biology. Results The aim of this study was to identify RNA binding proteins responsible for selective enrichment of exosome miRNAs in cancer cells. A biotin-labeled miR-1246 probe was used to capture RNA binding proteins (RBPs) from PANC-1 cells. Among the RBPs identified through proteomic analysis, SRSF1, EIF3B and TIA1 were highly associated with the miR-1246 probe. RNA immunoprecipitation (RIP) and electrophoretic mobility shift assay (EMSA) confirmed the binding of SRSF1 to miR-1246. Lentivirus shRNA knockdown of SRSF1 in pancreatic cancer cells selectively reduced exosome miRNA enrichment whereas GFP-SRSF1 overexpression enhanced the enrichment as analyzed by next generation small RNA sequencing and qRT-PCR. miRNA sequence motif analysis identified a common motif shared by 36/45 of SRSF1-associated exosome miRNAs. EMSA confirmed that shared motif decoys inhibit the binding of SRSF1 to the miR-1246 sequence. Conclusions We conclude that SRSF1 mediates selective exosome miRNA enrichment in pancreatic cancer cells by binding to a commonly shared miRNA sequence motif. Graphical abstract

We reported previously that, in budding yeast, transcription rate affects both the efficiency and fidelity of pre-mRNA splicing, especially of ribosomal protein transcripts. Here, we report that the majority of ribosomal protein transcripts with non-consensus 5′ splice sites are spliced less efficiently when transcription is faster, and more efficiently with slower transcription. These results support the “window of opportunity” model, and we suggest a possible mechanism to explain these findings.

Human exposure to nitrogen (N) pollution via nitrate in food and water and nitrogen oxides in the ambient air is reviewed. Increased risks of myocardial infarction, respiratory problems, and asthma have been linked to higher exposures to nitrogen oxides in ambient air. Excess nitrate/nitrite exposure in food and water may be harmful to human health by: (1) its contribution to the endogenous formation of N-nitroso compounds, demonstrated carcinogens and teratogens in animal models; (2) its potential role in methemoglobinemia; and (3) in high doses, its ability to competitively inhibit iodine uptake and induce changes in the thyroid. High nitrate levels in drinking water have been linked to methemoglobinemia in infants (“blue baby syndrome”) and children. In 2006, an International Agency for Research on Cancer expert panel concluded that ingested nitrate/nitrite under conditions that result in endogenous nitrosation is probably carcinogenic to humans; subsequent studies have continued to support this conclusion. Maternal exposures to higher nitrate levels in drinking water have been associated with a variety of adverse pregnancy outcomes. In contrast, maternal dietary intake of nitrate/nitrite has not been associated with birth defects in offspring unless coupled with prenatal nitrosatable drug exposure. Further research is indicated on the beneficial and harmful effects of nitrate on human health. Given what is currently known about the harmful effects of nitrogen oxides and ingested nitrate/nitrite, it appears prudent to support measures to reduce nitrogen emissions in the atmosphere and to continue to maintain current limits and guidelines on nitrate concentration in drinking water.

Climate change in northeastern North America is resulting in warmer winters with reduced snow accumulation. Soils under a thin snowpack are more likely to experience freeze–thaw cycles, disrupting carbon (C) and nitrogen (N) transformations. We conducted a 2 year snow removal experiment in Maine to study the effects of soil freezing on soil C and N processes. O horizon soils were sampled during winter and spring of 2015 and 2016, and they were analyzed for labile inorganic N and water-extractable organic carbon (WEOC) concentrations, specific ultraviolet absorbance (SUVA254), and potential net N mineralization. The winter of 2015 was cold and snowy, whereas 2016 was warm with a shallow, short-term snowpack. Snow removal caused the soils to freeze, but winter rain-on-soil events in 2015 resulted in the formation of concrete frost, as opposed to granular frost in 2016. Concrete frost increased soil ammonium (NH4+-N) and WEOC concentrations and decreased SUVA254, which we attribute to microbial cell lysis. In contrast, granular frost did not alter soil nutrient concentrations, reflecting limited microbial distress. Our study demonstrates that moisture content influences the intensity of soil freezing, highlighting the importance of snowpack depth and winter rain events in regulating winter and spring biogeochemical processes and nutrient availability.

Northeastern North America has been experiencing warmer winters with reduced snow accumulation, with more frequent winter freeze–thaw cycles. We conducted a laboratory experiment to investigate how increased frequency of freeze–thaw cycles (FTC) would alter soil C and N availability. Organic (O) and mineral (B) horizon soils were collected from a coniferous forest in Maine, processed to exclude roots, and then frozen in the laboratory (−10 °C) with one (FTC-1), two (FTC-2), or six (FTC-6) thaw periods (+5 °C). Soils were analyzed for extractable ammonium (NH4-N), water extractable organic carbon (WEOC), carbon dioxide flux (respiration), and total C and N. Extractable NH4-N increased following FTC (all levels), for both horizons. While WEOC concentrations did not change for FTC vs. control, the WEOC in O horizons had a lower SUVA254 in FTC soils compared to control, indicating a stronger microbial influence (i.e., microbial cell lysis) in these soils after FTC. Respiration in O horizon soils decreased post-incubation and did not differ between FTC and Control soils. In the B horizon, however, FTC soils showed greater respiration than Control soils, suggesting that the newly available nutrients may have stimulated microbial activity. In contrast to these results, total C and N remained unaltered by FTC, presumably because the FTC disturbances represented mostly a translocation of C and N from one pool into another, and losses due to respiration were too small to significantly influence the large TC and TN pools. The effect of FTC on NH4-N did not change with FTC frequency, suggesting that a single FTC is sufficient to alter both C and N availability and/or quality, and that additional FTC may not have a significant further effect. This study provides fresh insights on how organic and mineral horizon soils might respond to increased freeze–thaw frequency in winter.

Increased N inputs through chronic atmospheric deposition has enriched temperate forest ecosystems, altering critical ecosystem functions such as decomposition and potentially resulting in a shift to P limitation. We used a combination of microbial biomass stoichiometry and enzymatic activity analyses to evaluate the potential for microbial nutrient limitation over the course of a growing season in response to multi-decadal, whole-watershed N enrichments and a one time, plot-scale P addition that occurred in the 22nd year of whole-watershed treatments. The one-time P addition increased microbial biomass threefold and reduced N-acetyl-glucosaminidase (NAG) and acid phosphatase (AP) activity 1 week after application, but there was no interaction with long-term experimental N enrichment to indicate a shift to P limitation. However, both N and P treatments increased C limitation independently of each other over the duration of the study based on measured increases in β-1,4-glucosidase (BG) activity relative to NAG and AP. Microbial biomass stoichiometry and enzyme activity indicated that BBWM is P limited regardless of N status. Our findings highlight the complex interactions between C, N, and P use and limitation in a forested ecosystem subjected to long-term N enrichment.

Background: Despite international recommendations, coverage of syphilis testing in pregnant women and treatment of those found seropositive remains limited in sub-Saharan Africa. We assessed whether combining the provision of supplies with a behavioural intervention was more effective than providing supplies only, to improve syphilis screening and treatment during antenatal care. Methods: In this 18-month, cluster randomised controlled trial, we randomly assigned (1:1) 26 urban antenatal care clinics in Kinshasa, Democratic Republic of the Congo, and Lusaka, Zambia, to receive a behavioural intervention (opinion leader selection, academic detailing visits, reminders, audits and feedback, and supportive supervision) plus supplies for syphilis testing and treatment (intervention group) or to receive supplies only (control group). The primary outcomes were proportion of pregnant women who had syphilis screening out of the total who attended the clinic; and the proportion of women who had treatment with benzathine benzylpenicillin out of those who tested positive for syphilis at their first antenatal care visit. This trial is registered at ClinicalTrials.gov, number NCT02353117. Findings: The 18-month study period was Feb 1, 2016, to July 14, 2017. 18 357 women were enrolled at the 13 intervention clinics and 17 679 women were enrolled at the 13 control clinics at their first antenatal care visit. Syphilis screening was done in a median of 99·9% (IQR 99·0–100·0) of women in the intervention clinics and 93·8% (85·0–98·9) in the control clinics (absolute difference 6·1% [95% CI 1·1–14·1]; p=0·00092). Syphilis treatment at the first visit was done in a median of 100% (IQR 99·7–100·0) of seropositive women in intervention clinics and 43·2% (2·6–83·2) of seropositive women in control clinics (absolute difference 56·8% [12·8–99·0]; p=0·0028). Interpretation: A behavioural intervention, together with the provision of supplies, can lead to more than 95% of women being screened and treated for syphilis. The sole provision of supplies is sufficient to reach such levels of screening coverage but is not sufficient to ensure high levels of treatment. Funding: Bill & Melinda Gates Foundation. Fil: Althabe, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto de Efectividad Clínica y Sanitaria; Argentina. Organizacion Mundial de la Salud; Argentina Fil: Chomba, Elwyn. University Teaching Hospital of Lusaka; Zambia Fil: Tshefu, Antoinette K. University of Kinshasa; República Democrática del Congo Fil: Banda, Ernest. University Teaching Hospital of Lusaka; Zambia Fil: Belizán, María Melina Eleonora. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bergel, Eduardo. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Berrueta, Amanda Mabel. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Bertrand, Jane. University of Tulane; Estados Unidos Fil: Bose, Carl. University of North Carolina; Estados Unidos Fil: Cafferata, Maria Luisa. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Carlo, Waldemar A. University of Alabama at Birmingahm; Estados Unidos Fil: Ciganda, Alvaro. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Donnay, France. University of Tulane; Estados Unidos Fil: Garcia Elorrio, Ezequiel. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gibbons, Luz. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Klein, Karen. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Liljestrand, Jerker. Bill And Melinda Gates Foundation; Estados Unidos Fil: Lusamba, Paul D. University of Kinshasa; República Democrática del Congo Fil: Mavila, Arlette K. University of Kinshasa; República Democrática del Congo Fil: Mazzoni, Agustina. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Nkamba, Dalau M. University of Kinshasa; República Democrática del Congo Fil: Mwanakalanga, Friday H. University Teaching Hospital Lusaka; Zambia Fil: Mwapule Tembo, Abigail. University Teaching Hospital Lusaka; Zambia Fil: Mwenechanya, Musaku. University Teaching Hospital Lusaka; Zambia Fil: Pyne Mercier, Lee. Bill And Melinda Gates Foundation; Estados Unidos Fil: Spira, Cintia. Instituto de Efectividad Clínica y Sanitaria; Argentina Fil: Wetshikoy, Jean D. University of Kinshasa; República Democrática del Congo Fil: Xiong, Xu. University of Tulane; Estados Unidos Fil: Buekens, Pierre. University of Tulane; Estados Unidos

Agricultural compounds have been detected in drinking water, some of which are teratogens in animal models. The most commonly detected agricultural compounds in drinking water include nitrate, atrazine, and desethylatrazine. Arsenic can also be an agricultural contaminant, although arsenic often originates from geologic sources. Nitrate has been the most studied agricultural compound in relation to prenatal exposure and birth defects. In several case-control studies published since 2000, women giving birth to babies with neural tube defects, oral clefts, and limb deficiencies were more likely than control mothers to be exposed to higher concentrations of drinking water nitrate during pregnancy. Higher concentrations of atrazine in drinking water have been associated with abdominal defects, gastroschisis, and other defects. Elevated arsenic in drinking water has also been associated with birth defects. Since these compounds often occur as mixtures, it is suggested that future research focus on the impact of mixtures, such as nitrate and atrazine, on birth defects.

Bone loss and renal stone risk are longstanding concerns for astronauts. Bone resorption brought on by spaceflight elevates urinary calcium and the risk of renal stone formation. Loss of bone calcium leads to concerns about fracture risk and increased long-term risk of osteoporosis. Bone metabolism involves many factors and is interconnected with muscle metabolism and diet. We report here bone biochemistry and renal stone risk data from astronauts on 4- to 6-month International Space Station missions. All had access to a type of resistive exercise countermeasure hardware, either the Advanced Resistance Exercise Device (ARED) or the Interim Resistance Exercise Device (iRED). A subset of the ARED group also tested the bisphosphonate alendronate as a potential anti-resorptive countermeasure (Bis+ARED). While some of the basic bone marker data have been published, we provide here a more comprehensive evaluation of bone biochemistry with a larger group of astronauts. Regardless of exercise, the risk of renal stone formation increased during spaceflight. A key factor in this increase was urine volume, which was lower during flight in all groups at all time points. Thus, the easiest way to mitigate renal stone risk is to increase fluid consumption. ARED use increased bone formation without changing bone resorption, and mitigated a drop in parathyroid hormone in iRED astronauts. Sclerostin, an osteocyte-derived negative regulator of bone formation, increased 10-15% in both groups of astronauts who used the ARED (p

Traumatic injuries to PNS and CNS axons are not uncommon. Restoration of lost behaviors following severance of mammalian peripheral nerve axons (PNAs) relies on regeneration by slow outgrowths and is typically poor or nonexistent when after ablation or injuries close to the soma. Behavioral recovery after severing spinal tract axons (STAs) is poor because STAs do not naturally regenerate. Current techniques to enhance PNA and/or STA regeneration have had limited success and do not prevent the onset of Wallerian degeneration of severed distal segments. This Review describes the use of a recently developed polyethylene glycol (PEG) fusion technology combining concepts from biochemical engineering, cell biology, and clinical microsurgery. Within minutes after microsuturing carefully trimmed cut ends and applying a well-specified sequence of solutions, PEG-fused axons exhibit morphological continuity (assessed by intra-axonal dye diffusion) and electrophysiological continuity (assessed by conduction of action potentials) across the lesion site. Wallerian degeneration of PEG-fused PNAs is greatly reduced as measured by counts of sensory and/or motor axons and maintenance of axonal diameters and neuromuscular synapses. After PEG-fusion repair, cut-severed, crush-severed, or ablated PNAs or crush-severed STAs rapidly (within days to weeks), more completely, and permanently restore PNA- or STA-mediated behaviors compared with nontreated or conventionally treated animals. PEG-fusion success is enhanced or decreased by applying antioxidants or oxidants, trimming cut ends or stretching axons, and exposure to Ca(2+) -free or Ca(2+) -containing solutions, respectively. PEG-fusion technology employs surgical techniques and chemicals already used by clinicians and has the potential to produce a paradigm shift in the treatment of traumatic injuries to PNAs and STAs.

The loss of bone mass and alteration in bone physiology during space flight are one of the major health risks for astronauts. Although the lack of weight bearing in microgravity is considered a risk factor for bone loss and possible osteoporosis, organisms living in space are also exposed to cosmic radiation and other environmental stress factors. As such, it is still unclear as to whether and by how much radiation exposure contributes to bone loss during space travel, and whether the effects of microgravity and radiation exposure are additive or synergistic. Bone is continuously renewed through the resorption of old bone by osteoclast cells and the formation of new bone by osteoblast cells. In this study, we investigated the combined effects of microgravity and radiation by evaluating the maturation of a hematopoietic cell line to mature osteoclasts. RAW 264.7 monocyte/macrophage cells were cultured in rotating wall vessels that simulate microgravity on the ground. Cells under static 1g or simulated microgravity were exposed to γ rays of varying doses, and then cultured in receptor activator of nuclear factor-κB ligand (RANKL) for the formation of osteoclast giant multinucleated cells (GMCs) and for gene expression analysis. Results of the study showed that radiation alone at doses as low as 0.1 Gy may stimulate osteoclast cell fusion as assessed by GMCs and the expression of signature genes such as tartrate resistant acid phosphatase (Trap) and dendritic cell-specific transmembrane protein (Dcstamp). However, osteoclast cell fusion decreased for doses greater than 0.5 Gy. In comparison to radiation exposure, simulated microgravity induced higher levels of cell fusion, and the effects of these two environmental factors appeared additive. Interestingly, the microgravity effect on osteoclast stimulatory transmembrane protein (Ocstamp) and Dcstamp expressions was significantly higher than the radiation effect, suggesting that radiation may not increase the synthesis of adhesion molecules as much as microgravity. published

The plants are a rich source of drugs because they produce a variety of bioactive molecules, most of which probably act as chemical defence against predators or pathogens. The present study was conducted to determine the phytochemical constituents and the acute toxicity of aqueous extracts, ethanolic and methanolic of stem bark from Entandrophragma angolense in rats. The acute toxicity studies were carried out on the basis of the guidelines of the OECD 423. The aqueous extracts, ethanolic and methanolic were administered orally at a single dose of 300, 2000 and 5000 mg / kg body weight to the rats. The extracts showed lesser toxicity at dose of 2000 mg / kg body weight; however at 5000 mg/kg body weight dose the mortality rate was 2/3. Thus, the Lethal Dose 50(DL50) is in the range of 2000 to 5000 mg / kg body weight. These results suggest that the aqueous extracts, ethanolic and methanolic of stem bark of E. angolense could be used with some degree of safety by oral route. Phytochemical analysis of aqueous extracts, ethanolic and methanolic of stem bark of E. angolense revealed the presence of alkaloids, saponins, tannins, flavonoids, terpenoids, quinones, cardiac glycosides, leucoanthocyanins, phenols and steroids. These extracts contain important bioactive compounds, which justifies the use of this plant in traditional medicine for the treatment of various diseases.

The fluorescence of organic fluorophore molecules is enhanced when they are placed in contact with certain metals (Al, Ag, Cu, Au, etc.) whose surface plasmon waves couple into the radiative modes of the molecules and increase the radiative efficiency. Here, we report a hitherto unknown size dependence of this metal-enhanced fluorescence (MEF) effect in the nanoscale. When the molecules are deposited in nanoporous anodic alumina films with exposed aluminum at the bottom of the pores, they form organic nanowires standing on aluminum nanoparticles whose plasmon waves have much larger amplitudes. This increases the MEF strongly, resulting in several orders of magnitude increase in the fluorescence intensity of the organic fluorophores. The increase in intensity shows an inverse superlinear dependence on nanowire diameter because the nanowires also act as plasmonic "waveguides" that concentrate the plasmons and increase the coupling of the plasmons with the radiative modes of the molecules. Furthermore, if the nanoporous template housing the nanowires has built-in electric fields due to space charges, a strong molecule-specific red- or blue-shift is induced in the fluorescence peak owing to a renormalization of the dipole moment of the molecule. This can be exploited to detect minute amounts of target molecules in a mixture using their optical signature (fluorescence) despite the presence of confounding background signals. It can result in a unique new technology for biosensing and chemical sensing.

Previous epidemiologic studies of maternal exposure to drinking water nitrate did not account for bottled water consumption. The objective of this National Birth Defects Prevention Study (NBDPS) (USA) analysis was to assess the impact of bottled water use on the relation between maternal exposure to drinking water nitrate and selected birth defects in infants born during 1997–2005. Prenatal residences of 1,410 mothers reporting exclusive bottled water use were geocoded and mapped; 326 bottled water samples were collected and analyzed using Environmental Protection Agency Method 300.0. Median bottled water nitrate concentrations were assigned by community; mothers' overall intake of nitrate in mg/day from drinking water was calculated. Odds ratios for neural tube defects, limb deficiencies, oral cleft defects, and heart defects were estimated using mixed-effects models for logistic regression. Odds ratios (95% CIs) for the highest exposure group in offspring of mothers reporting exclusive use of bottled water were: neural tube defects [1.42 (0.51, 3.99)], limb deficiencies [1.86 (0.51, 6.80)], oral clefts [1.43 (0.61, 3.31)], and heart defects [2.13, (0.87, 5.17)]. Bottled water nitrate had no appreciable impact on risk for birth defects in the NBDPS.

Objective— Intracellular cholesterol distribution impacts cell function; however, processes influencing endogenous cholesterol trafficking remain largely unknown. Atherosclerosis is associated with vascular inflammation and these studies address the role of inflammatory mediators on smooth muscle cell cholesterol trafficking. Methods and Results— Interestingly, in the absence of an exogenous cholesterol source, serum amyloid A increased [ 14 C] oleic acid incorporation into cholesteryl ester in rat smooth muscle cells, suggesting endogenous cholesterol trafficking to the endoplasmic reticulum. [ 3 H] cholesteryl ester accumulated in cells prelabeled with [ 3 H] cholesterol, confirming that serum amyloid A mediated the movement of endogenous cholesterol. Cholesterol movement was dependent upon functional endolysosomes. The cholesterol oxidase–sensitive pool of cholesterol decreased in serum amyloid A−treated cells. Furthermore, the mechanism whereby serum amyloid A induced cholesterol trafficking was determined to be via activation of expression of secretory phospholipase A 2 , group IIA (sPLA 2 ) and sPLA 2 –dependent activation of sphingomyelinase. Interestingly, although neither tumor necrosis factor-α nor interferon-γ induced cholesterol trafficking, interleukin-1β induced [ 14 C] cholesteryl ester accumulation that was also dependent upon sPLA 2 and sphingomyelinase activities. Serum amyloid A activates smooth muscle cell interleukin-1β expression, and although the interleukin-1–receptor antagonist inhibited the interleukin-1β−induced cholesterol trafficking, it had no effect on the movement of cholesterol mediated by serum amyloid A. Conclusion— These data support a role for inflammation in endogenous smooth muscle cell cholesterol trafficking from the plasma membrane to the endoplasmic reticulum.

Animal models and human studies suggest that osteocytes regulate the skeleton's response to mechanical unloading in part by an increase in sclerostin. However, few studies have reported changes in serum sclerostin in humans exposed to reduced mechanical loading.We determined changes in serum sclerostin and bone turnover markers in healthy adult men undergoing controlled bed rest.Seven healthy adult men (31 ± 3 yr old) underwent 90 d of 6° head down tilt bed rest at the University of Texas Medical Branch Institute for Translational Sciences-Clinical Research Center.Serum sclerostin, PTH, vitamin D, bone resorption and formation markers, urinary calcium and phosphorus excretion, and 24-h pooled urinary markers of bone resorption were evaluated before bed rest [baseline (BL)] and at bed rest d 28 (BR-28), d 60 (BR-60), and d 90 (BR-90). Bone mineral density was measured at BL, BR-60, and 5 d after the end of the study (BR+5). Data are reported as mean ± SD.Consistent with prior reports, bone mineral density declined significantly (1-2% per month) at weight-bearing skeletal sites. Serum sclerostin was elevated above BL at BR-28 (+29 ± 20%; P = 0.003) and BR-60 (+42 ± 31%; P0.001), with a lesser increase at BR-90 (+22 ± 21%; P = 0.07). Serum PTH levels were reduced at BR-28 (-17 ± 16%; P = 0.02) and BR-60 (-24 ± 14%; P = 0.03) and remained lower than BL at BR-90 (-21 ± 21%; P = 0.14), but did not reach statistical significance. Serum bone turnover markers were unchanged; however, urinary bone resorption markers and calcium were significantly elevated at all time points after bed rest (P0.01).In healthy men subjected to controlled bed rest for 90 d, serum sclerostin increased, with a peak at 60, whereas serum PTH declined, and urinary calcium and bone resorption markers increased.

Although common disturbances of grazing lands like plant defoliation are expected to affect their sensitivity to increasing atmospheric CO2 concentration, almost no research has been conducted to evaluate how important such effects might be on the direct responses of rangelands to CO2. This growth chamber experiment subjected intact plant–soil cylinders from a Wyoming, USA, prairie to a 3-way factorial of CO2 (370 vs. 720 μL L−1), defoliation (non-clipped vs. clipped) and soil nitrogen (control vs. 10 g m−2 added N) under simulated natural climatic conditions. Above- and below-ground biomass and N dynamics of the functional groups C3 grasses, C4 grasses and forbs were investigated. CO2 and defoliation had independent influences on biomass and N parameters of these rangeland plants. Growth under CO2-enriched conditions enhanced above-ground biomass 50% in C3 grasses alone, while shoot N concentration declined 16% in both C3 and C4 grasses. Plant-soil 15N uptake was unaffected by CO2 treatment. In contrast, defoliation had no effect on biomass, but increased tissue N concentration 29% across all functional groups. Without additional N, forage quality, which is in direct relation to N concentration, will decline under increasing atmospheric CO2. Increased dominance of C3 grasses plus reduced forage quality may necessitate changes in grazing management practices in mixed-species rangelands.

Elevated CO 2 and defoliation effects on nitrogen (N) cycling in rangeland soils remain poorly understood. Here we tested whether effects of elevated CO 2 (720 μl L −1 ) and defoliation (clipping to 2.5 cm height) on N cycling depended on soil N availability (addition of 1 vs. 11 g N m −2 ) in intact mesocosms extracted from a semiarid grassland. Mesocosms were kept inside growth chambers for one growing season, and the experiment was repeated the next year. We added 15 N (1 g m −2 ) to all mesocosms at the start of the growing season. We measured total N and 15 N in plant, soil inorganic, microbial and soil organic pools at different times of the growing season. We combined the plant, soil inorganic, and microbial N pools into one pool (PIM-N pool) to separate biotic + inorganic from abiotic N residing in soil organic matter (SOM). With the 15 N measurements we were then able to calculate transfer rates of N from the active PIM-N pool into SOM (soil N immobilization) and vice versa (soil N mobilization) throughout the growing season. We observed significant interactive effects of elevated CO 2 with N addition and defoliation with N addition on soil N mobilization and immobilization. However, no interactive effects were observed for net transfer rates. Net N transfer from the PIM-N pool into SOM increased under elevated CO 2 , but was unaffected by defoliation. Elevated CO 2 and defoliation effects on the net transfer of N into SOM may not depend on soil N availability in semiarid grasslands, but may depend on the balance of root litter production affecting soil N immobilization and root exudation affecting soil N mobilization. We observed no interactive effects of elevated CO 2 with defoliation. We conclude that elevated CO 2 , but not defoliation, may limit plant productivity in the long-term through increased soil N immobilization.

Nitrosatable drugs, such as secondary or tertiary amines and amides, form N-nitroso compounds in the presence of nitrite. Various N-nitroso compounds have been associated with neural tube defects in animal models. Using data from the National Birth Defects Prevention Study, the authors examined nitrosatable drug exposure 1 month before and 1 month after conception in 1,223 case mothers with neural tube defect-affected pregnancies and 6,807 control mothers who delivered babies without major congenital anomalies from 1997 to 2005. Nitrite intakes were estimated from mothers' responses to a food frequency questionnaire. After adjustment for maternal race/ethnicity, educational level, and folic acid supplementation, case women were more likely than were control women to have taken tertiary amines (odds ratio = 1.60, 95% confidence interval (CI): 1.31, 1.95). This association was strongest with anencephalic births (odds ratio = 1.96, 95% CI: 1.40, 2.73); odds ratios associated with tertiary amines from the lowest tertile of nitrite intake to the highest tertile were 1.16 (95% CI: 0.59, 2.29), 2.19 (95% CI: 1.25, 3.86), and 2.51 (95% CI: 1.45, 4.37), respectively. Odds ratios for anencephaly with nitrosatable drug exposure were reduced among women who also took daily vitamin supplements that contained vitamin C. Prenatal exposure to nitrosatable drugs may increase the risk of neural tube defects, especially in conjunction with a mother's higher dietary intake of nitrites, but vitamin C might modulate this association.

The photochemical reflectance index (PRI) is correlated to photosynthetic efficiency and has been successfully applied at multiple scales for remote estimation of physiological functioning. However, interpretation of the PRI signal can be confounded by many different variables including declines in photochemical pigments. Our study was aimed at investigating PRI in response to salinity stress, and evaluating physiological and pigment responses of two co-occurring shrubs, Baccharis halimifolia and Myrica cerifera in laboratory studies. Photosynthesis, water relations, chlorophyll fluorescence, hyperspectral reflectance and leaf pigment contents were measured following salinity treatment. Physiological measurements indicated that both species exhibit adaptations which protect PSII during periods of stress. Chlorophyll fluorescence parameters were affected in both species, but indicated that other photochemical reactions (e.g. photorespiration) were important for energy dissipation in absence of chlorophyll changes. After many days of reduced photosynthesis, photochemical changes were detectable using PRI indicating chronic stress. Variations in PRI were not related to changes in pigments but strongly related to tissue chlorides indicating salinity effects on the PRI signal. Thus, PRI is an indicator of salinity stress in these coastal species and may be as an early signal for increasing salt exposure associated with rising sea-level and climate change.

BACKGROUND: To better understand the neural tube defect (NTD) causal pathway, the authors measured homocysteine, an indicator of tissue micronutrient deficiencies. The authors examined independent and joint associations of serum homocysteine, B12, and folate and red blood cell (RBC) folate with NTD-affected pregnancies. METHODS: Case women in this population-based study had NTD-affected pregnancies and resided and delivered in one of the 14 Texas-Mexico border counties from 1995 through 2000. Control women were study area residents delivering normal live births during the same period. The authors measured homocysteine levels using tandem mass spectroscopy; competitive binding was used for other biomarkers. RESULTS: Homocysteine testing was done on 103 cases and 139 controls. Odds ratios (ORs) were increased in all upper homocysteine quintiles compared to the lowest quintile (1.7, 1.3, 2.8, 2.4). Women with high homocysteine values had increased ORs regardless of high versus low levels for B12 (OR = 3.5, 4.8, respectively) or RBC folate (OR = 2.9, 3.5, respectively). CONCLUSIONS: High serum homocysteine levels are associated with NTD-affected pregnancies. Moreover, high homocysteine levels have a detrimental effect on NTD-risk even when serum B12 or RBC folate levels are high. Excess homocysteine might play an independent role in the development of NTDs. Birth Defects Research (Part A), 2009. © 2009 Wiley-Liss, Inc.

A passive signal enhancement device for the standoff detection of uranium in soil was developed and tested. The device consists of a spherical ball lens half-coated with a polymer–silica gel composite. The nanoporous silica gel, when placed in contact with moist soil, absorbs water and dissolved uranyl ions and significantly enhances the fluorescence intensity of the uranyl. The ball lens focuses the UV excitation energy to the focal point of the lens located within the silica gel layer and directs the resulting fluorescence signal back towards the excitation source. Our results show that this ‘Directed Fluorescence’ (DF) device can be used to enhance the uranyl fluorescence signal intensity by more than 200 times. Consequently, the maximum standoff detection distance is increased by more than an order of magnitude.

A series of models using cellular automata (CA) are created to examine the influences on the phenomenon of solute aggregation. The models used the variations in hydropathic states of the solutes to produce changes in the clustering patterns. It was found that an increase in the hydrophobic character of the solute molecules led to greater aggregation. The effect of concentration of solutes was also modeled. These preliminary models of solute aggregation serve as the basis for subsequent models relative to both biological receptor interactions, and the fate and transport of environmental contaminants of interest.

A cellular automata (CA) model of liquid water has been used to study self-diffusion and the diffusion of a solute. The influences of temperature and solute hydropathic state are modeled as variables in this process. The self-diffusion model correlates very well with earlier experimental data. The diffusion of a solute experiences variation with temperature and its hydropathic states. These influences are found to relate to models of free hydroxy groups and the average cavity cluster size in bulk water. These preliminary models serve as the basis for modeling solute diffusion for specific contaminants of interest (such as heavy metals like uranium) in a water system, and addressing its migration patterns with water relative to temperature.

The search for new molecules to fight Pseudomonas aeruginosa is of paramount importance. Carbon monoxide (CO) is known to act as an effective inhibitor of the respiratory chain in P. aeruginosa, but the practical use of this gas as an antibacterial molecule is hampered by its toxicity and difficulty to manipulate. Here, we show that a water-soluble CO releaser (CORM-3) possesses bactericidal properties against laboratory and antibiotic-resistant P. aeruginosa. CORM-3 reduced the bacterial count by 4 logs 180 min after in vitro treatment. CORM-3-treated bacteria had a lower O(2) consumption than vehicle-treated bacteria, and the decrease in O(2) consumption temporally preceded the bactericidal action of CORM-3. These results support the hypothesis that the antimicrobial effect of CORM-3 is mediated by an interaction of CO liberated by the carrier with the bacterial respiratory chain. The antibacterial effect occurred at concentrations of CORM-3 that are 50-fold lower than toxic concentrations for eukaryotic cells. CORM-3 treatment compared to vehicle treatment decreased bacterial counts in the spleen and increased survival in immunocompetent and immunosuppressed mice following P. aeruginosa bacteremia. Our results suggest that CORMs could form the basis for developing a new therapeutic strategy against P. aeruginosa-induced infection.

Modification of the implant surface with the Arg-Gly-Asp tripeptide (RGD) putatively facilitates osteoblast attachment for improved implant fixation in the laboratory. We compared the histomorphometric and mechanical performance of titanium implants coated with RGD using a novel interface of self-assembled monolayers of phosphonates (RGD/SAMP) and implants coated with RGD using the more conventional thiolate-gold interface (RGD/thiolate-gold). We hypothesized RGD/SAMP-coated implants would show greater bone ongrowth and implant fixation than RGD/thiolate-gold-coated ones. We implanted an RGD/SAMP-coated implant in one femur and an RGD/thiolate-gold-coated in the contralateral femur of 60 rats. At 2, 4, and 8 weeks after implantation, 10 rats were sacrificed for histologic evaluation and another 10 for biomechanical testing. Bone-implant ongrowth and implant force-to-failure of the two implants were similar at all times. Although RGD/SAMP-coated implants did not show superior bone ongrowth and implant fixation, RGD/SAMP-coated implants have at least equally good histomorphometric and mechanical in vivo performance as RGD/thiolate-gold-coated ones. Additional in vivo characterization of self-assembled monolayer films of phosphonates as interface to bond RGD to titanium is needed to explore its full potential and seems justified based on the results of this study.

Although major metabolites of some antidepressant drugs are known to be active, their pharmacological effects are poorly characterized. Two of the most selective antidepressants, desipramine (selectively inhibits norepinephrine reuptake) and citalopram (selectively inhibits serotonin reuptake) are frequently used in animal studies of antidepressant action, as well as being useful therapeutically. The primary aim of this study was to determine the affinity of desmethyldesipramine, an active metabolite of desipramine, for the rat norepinephrine and serotonin transporters, as well as for the rat α 2 -adrenoceptor. The pharmacological characteristics of desmethyldesipramine and desmethylcitalopram, an active metabolite of citalopram, were also determined for various human transporters and neurotransmitter receptors. Competition binding studies using [ 3 H]nisoxetine and [ 3 H]citalopram showed desipramine to be 25 times more selective for the rat norepinephrine as compared to serotonin transporter (6.2 nM vs. 158 nM) whereas desmethyldesipramine is 12 times more selective for the serotonin over the norepinephrine transporter (12.8 nM vs. 153 nM). Interestingly, the affinity of desmethyldesipramine for the serotonin transporter is similar to the affinity of desipramine for the norepinephrine transporter. Desipramine and desmethyldesipramine were found to have a lower affinity for the rat α 2A(D) -adrenoceptor than the transporters, suggesting that this receptor is not a major site of action for either compound. Thus, the pharmacological effects of desipramine in rats may be attributed not only to the inhibition of the norepinephrine transporter by desipramine but also to the inhibition of serotonin transporter by the active metabolite desmethyldesipramine.

Although the tricyclic antidepressants, such as desipramine (DMI), are among the most efficacious treatments for adult depression, they are not effective in treating childhood and adolescent depression. Because the adrenergic nervous system is not fully developed until late adolescence, we hypothesized that the mechanisms regulating receptor density may not yet be mature in young mammals. To test this hypothesis, the effects of DMI treatment on cortical alpha-1-, alpha-2-, and beta-adrenergic receptors were compared in juvenile and adult rats. DMI was delivered either by 4 days of twice daily injections to postnatal day 9 to 13 (4 and 7 mg/kg/day) and adult (20 mg/kg/day) rats, or by 2 weeks of continual drug infusion (osmotic minipumps) to postnatal day 21-35 (15 mg/kg/day) and adult (10 mg/kg/day) rats. These delivery paradigms gave juvenile brain concentrations of DMI similar to those in adult rats. The beta-adrenergic receptor was down-regulated with both treatment paradigms in both juvenile and adult rats. By contrast, in the postnatal day 9 to 13 rats, there was a dose-dependent up-regulation of the alpha-1 in the cortex and alpha-2-adrenergic receptor in the prefrontal cortex, whereas there was no change in density in adult rats. These differences in the alpha-adrenergic receptor regulation after DMI treatment suggest that the lack of efficacy of tricyclic antidepressants in treating childhood depression may be related to immature regulatory mechanisms for these receptors.

Parts of New England have naturally high arsenic concentrations in groundwater. High arsenic correlates broadly with bedrock type, but levels are patchy, so other conditions must affect arsenic mobilization. Microorganisms capable of arsenate (As(V)) respiration, if present, could affect arsenic speciation and mobility in groundwater. An arsenate-reducing bacterium, designated NP4, was isolated from groundwater obtained from a well in Northport, Me., with extremely high (>1,400 μg L−1 ) arsenic. Sequencing of the 16S rDNA showed that NP4 groups with the Sulfurospirillum genus. It can grow using arsenate, nitrate, iron(III), selenate, manganese(IV), sulfite, sulfur or thiosulfate as terminal electron acceptors and lactate, formate and pyruvate as electron donors. It can also grow on fumarate or lactate alone. This Sulfurospirillum isolate is distinct from other members of the genus in its carbon and electron acceptor usage. The activity of this type of microorganism could negatively affect groundwater qual...

The recent growth in production and utilization of natural gas offers potential climate benefits, but those benefits depend on lifecycle emissions of methane, the primary component of natural gas and a potent greenhouse gas. This study estimates methane emissions from the transmission and storage (TS) sector of the United States natural gas industry using new data collected during 2012, including 2,292 onsite measurements, additional emissions data from 677 facilities and activity data from 922 facilities. The largest emission sources were fugitive emissions from certain compressor-related equipment and "super-emitter" facilities. We estimate total methane emissions from the TS sector at 1,503 [1,220 to 1,950] Gg/yr (95% confidence interval) compared to the 2012 Environmental Protection Agency's Greenhouse Gas Inventory (GHGI) estimate of 2,071 [1,680 to 2,690] Gg/yr. While the overlap in confidence intervals indicates that the difference is not statistically significant, this is the result of several significant, but offsetting, factors. Factors which reduce the study estimate include a lower estimated facility count, a shift away from engines toward lower-emitting turbine and electric compressor drivers, and reductions in the usage of gas-driven pneumatic devices. Factors that increase the study estimate relative to the GHGI include updated emission rates in certain emission categories and explicit treatment of skewed emissions at both component and facility levels. For TS stations that are required to report to the EPA's Greenhouse Gas Reporting Program (GHGRP), this study estimates total emissions to be 260% [215% to 330%] of the reportable emissions for these stations, primarily due to the inclusion of emission sources that are not reported under the GHGRP rules, updated emission factors, and super-emitter emissions.

Prenatal exposure to nitrosatable drugs, including secondary or tertiary amines, has been associated with preterm birth. Associations may be accentuated by higher intakes of dietary nitrites because of the increased formation of N-nitroso compounds. Using data from mothers of babies without major birth defects (controls) from the National Birth Defects Prevention Study, we examined the relationship between nitrosatable drug exposure in conjunction with dietary nitrite intake and preterm birth among 496 mothers of preterm infants and 5,398 mothers with full-term deliveries in 1997-2005. A protective association was observed with a high intake of plant nitrites (adjusted hazard ratio (AHR) = 0.72, 95% confidence interval (CI): 0.53, 0.97). Secondary amines in conjunction with high nitrite intake were associated with preterm birth during the first (AHR = 1.84, 95% CI: 1.14, 2.98), second (AHR = 1.89, 95% CI: 1.17, 3.07), and third (AHR = 2.00, 95% CI: 1.22, 3.29) trimesters. The adjusted hazard ratios for tertiary amine use in the third trimester by increasing tertiles of nitrite intake were 0.67 (95% CI: 0.35, 1.31), 1.25 (95% CI: 0.71, 2.19), and 2.02 (95% CI: 1.17, 3.49). Prenatal exposure to nitrosatable drugs, particularly secondary and tertiary amines, in conjunction with higher levels of dietary nitrite intake may increase the risk of preterm birth.

Evidence from animal and epidemiologic studies suggests that ingestion of nitrosatable precursors, such as amines, amides, and nitrites, might increase the risk of congenital malformations through the endogenous formation of N-nitroso compounds. This chapter focuses on the potential separate and combined effects of nitrosatable drugs, dietary intake of nitrate and nitrite, and exposure to nitrate in drinking water on the risk of birth defects. Nitrosatable drugs are amines or amides that can react with nitrite in an acidic environment, such as in the stomach, to form N-nitroso compounds. Significant associations have been observed between prenatal exposures to nitrosatable drugs and several types of birth defects, especially among offspring of mothers who also had a higher dietary intake of nitrate and nitrite. Findings of recent studies indicate that some associations between nitrosatable drugs and birth defects are diminished among mothers who take daily supplements and/or consume adequate amounts of vitamin C, a known inhibitor of nitrosation.

Use of herbicides to thin dense stands of Artemisia spp. (sagebrush) can free up resources for herbaceous plants and increase forage production, but may also facilitate weed invasion. We revisited a sagebrush thinning experiment in a north central Wyoming big sagebrush–grassland 11 years after application of tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N-N′-dimethylurea) to determine the long-term responses of shrubs, available soil resources, perennial grasses, and Bromus tectorum L. (downy brome). Tebuthiuron reduced shrub cover by more than half, from 31% in untreated plots to 15% in treated plots (P = 0.002), and increased downy brome cover approximately 4-fold, from 0.9% in untreated plots to 3.5% in treated plots (P = 0.02). Treatment with tebuthiuron also resulted in marginally significant increases in cover of perennial grasses (from 9% to 12.3%; P = 0.07) and bare ground (from 39.1% to 43.9%; P = 0.08). In comparisons of resource availability among microsites, available N...

DNA vaccines expressing the envelope (env) of the human immunodeficiency virus type 1 (HIV-1) have been relatively ineffective at generating strong immune responses. In this study, we described the development of a recombinant plasmid DNA (pEK2P-B) expressing an engineered codon-optimized envelope gp140 gene of primary (nonrecombinant) HIV-1 subtype B isolate 6101. Codon usage and RNA optimization of HIV-1 structural genes has been shown to increase protein expression in vitro as well as in the context of DNA vaccines in vivo. To further increase the expression, a synthetic IgE leader with kozak sequences were fused into the env gene. The cytoplasmic tail of the gene was also truncated to prevent recycling. The expression of env by the recombinant pEK2P-B was evaluated using T7 coupled transcription/translation. The construct demonstrated high expression of the HIV-1 env gene in eukaryotic cells as demonstrated in transfected 293-T and RD cells. Immunogenicity of pEK2P-B was evaluated in mice using IFN-gamma ELISpot assay, and the construct was found to be highly immunogenic and crossreactive with HIV-1 clade C env peptides. Three immunodominant peptides were also mapped out. Furthermore, by performing a CFSE flow cytometry-based proliferation assay, 2.4 and 1.5% proliferation was observed in CD4+, CD8+, and CCR+ memory T cells, respectively. Therefore, this engineered synthetic optimized env DNA vaccine may be useful in DNA vaccine and other studies of HIV-1 immunogenicity.

Arsenic, cadmium, lead, and mercury are neurotoxins, and some studies suggest that these elements might also be teratogens. Using a case-control study design, we investigated the relation between exposure to these heavy metals and neural tube defects (NTDs) in offspring of Mexican-American women living in 1 of the 14 Texas counties bordering Mexico. A total of 184 case-women with NTD-affected pregnancies and 225 control-women with normal live births were interviewed about their environmental and occupational exposures during the periconceptional period. Biologic samples for blood lead and urinary arsenic, cadmium, and mercury were also obtained for a subset of these women. Overall, the median levels of these biomarkers for heavy metal exposure did not differ significantly (P > 0.05) between case- and control-women. However, among women in the highest income group, case-women were nine times more likely (95% confidence interval (CI) 1.4-57) than control-women to have a urinary mercury 5.62 microg/L. Case-women were 4.2 times more likely (95% CI 1.1-16) to report burning treated wood during the periconceptional period than control-women. Elevated odds ratios (ORs) were observed for maternal and paternal occupational exposures to arsenic and mercury, but the 95% CIs were consistent with unity. The 95% CIs of the ORs were also consistent with unity for higher levels of arsenic, cadmium, lead, and mercury in drinking water and among women who lived within 2 miles at the time of conception to industrial facilities with reported emissions of any of these heavy metals. Our findings suggest that maternal exposures to arsenic, cadmium, or lead are probably not significant risk factors for NTDs in offspring. However, the elevated urinary mercury levels found in this population and exposures to the combustion of treated wood may warrant further investigation.

Dihydrotestosterone in androgen target tissues is formed under most circumstances by the 5alpha-reduction of testosterone, but an alternate pathway involves the oxidation of androstanediol to dihydrotestosterone. To investigate the mechanism by which androgens virilize the Wolffian ducts in the tammar wallaby, [(3)H]progesterone was incubated with testes from d 10 and 19 pouch young, and radioactivity was recovered in testosterone and androstanediol at both ages. Analysis of the intermediates indicates that androstanediol was formed both from testosterone via 5alpha-reduction and 3alpha-keto reduction and directly from 5alpha-reduced progestogens. 5alpha-Reductase activity was high in minces of mesonephros/epididymis from d 6-21 pouch young. When minces of urogenital tract tissues from d 19 pouch young were incubated with [(3)H]testosterone, [(3)H]dihydrotestosterone, and [(3)H]androstanediol, dihydrotestosterone was the principal androgen formed in the mesonephros/epididymis, urogenital sinus, and urogenital tubercle, whereas androstanediol was the principal androgen formed by the testis. In intact pouch young studied between d 10 and 34, administration of the 5alpha-reductase inhibitor, 17beta-(N,N-diethyl)carbamoyl-4-methyl-4-aza-5alpha-androstan-3-one, blocked virilization of the Wolffian ducts in males, and administration of androstanediol caused virilization of the Wolffian ducts in females. We conclude that dihydrotestosterone, largely formed in the tissue by the oxidation of androstanediol derived from the testes and also the 5alpha-reduction of testosterone, is responsible for Wolffian duct virilization in this species.

Human alteration of the nitrogen cycle has resulted in steadily accumulating nitrate in our water resources. The U.S. maximum contaminant level and World Health Organization guidelines for nitrate in drinking water were promulgated to protect infants from developing methemoglobinemia, an acute condition. Some scientists have recently suggested that the regulatory limit for nitrate is overly conservative; however, they have not thoroughly considered chronic health outcomes. In August 2004, a symposium on drinking-water nitrate and health was held at the International Society for Environmental Epidemiology meeting to evaluate nitrate exposures and associated health effects in relation to the current regulatory limit. The contribution of drinking-water nitrate toward endogenous formation of N-nitroso compounds was evaluated with a focus toward identifying subpopulations with increased rates of nitrosation. Adverse health effects may be the result of a complex interaction of the amount of nitrate ingested, the concomitant ingestion of nitrosation cofactors and precursors, and specific medical conditions that increase nitrosation. Workshop participants concluded that more experimental studies are needed and that a particularly fruitful approach may be to conduct epidemiologic studies among susceptible subgroups with increased endogenous nitrosation. The few epidemiologic studies that have evaluated intake of nitrosation precursors and/or nitrosation inhibitors have observed elevated risks for colon cancer and neural tube defects associated with drinking-water nitrate concentrations below the regulatory limit. The role of drinking-water nitrate exposure as a risk factor for specific cancers, reproductive outcomes, and other chronic health effects must be studied more thoroughly before changes to the regulatory level for nitrate in drinking water can be considered.