Changes in bovine leukemia virus serological status and lymphocyte count between dry-off and early lactation in Michigan dairy cows

This study addresses how the serological status of bovine leukemia virus (BLV) and lymphocyte count fluctuate from dry-off to early lactation in dairy cattle. Very few studies have investigated how BLV antibody status and lymphocyte count of cows changes longitudinally during the lactation cycle. Blood samples were collected from dairy cattle (n = 149) on 5 commercial dairy herds in Michigan at dry-off, close-up, and 7 to 10 d after calving. Plasma was analyzed for anti-BLV antibodies using a BLV-ELISA and whole blood was analyzed for lymphocyte counts. We found that BLV seroprevalence increased from dry-off (38.9%) to close-up (43.6%), then slightly decreased from close-up to 7 to 10 d after calving (43.0%). However, the change in seroprevalence was only significant from dry-off to close-up. Cows of third or higher parity were more likely to seroconvert than cows of lower parity and had the highest ELISA-negative prevalence of BLV. Lymphocyte counts were significantly higher in ELISA-positive animals, but only among second and third or greater parity animals. These results indicate that the use of lymphocyte counts as a disease severity monitoring tool for BLV should differ by parity group. Future studies should investigate if changes in seroprevalence are due to new infections or natural changes in antibody concentrations as the cow prepares for colostrum production. More accurate lymphocyte guidelines to be used for monitoring the progression of BLV should be created that consider parity and lactation stage.

Outcome of autoimmune cytopenia after hematopoietic cell transplantation in primary immunodeficiency

BACKGROUND

Post hematopoietic cell transplantation (HCT) autoimmune cytopenia (AIC) is a potentially life-threatening complication, but studies focusing on large cohorts of patients transplanted for primary immunodeficiency are lacking.

OBJECTIVES

This study sought to determine the incidence, risk factors, and outcomes of post-HCT AIC and B-lymphocyte function following rituximab.

METHODS

We retrospectively studied 502 children with primary immunodeficiency who were transplanted at our center between 1987 and 2018.

RESULTS

Thirty-six patients (9%) developed post-HCT AIC, with a median onset of 6.5 months post-HCT. On univariate analysis, pre-HCT AIC, mismatched donor, alemtuzumab, anti-thymocyte antiglobulin, and acute and chronic graft versus host disease were significantly associated with post-HCT AIC. After multivariate analysis, alemtuzumab (subdistribution hazard ratio, 9.0; 95% CI, 1.50-54.0; P = .02) was independently associated with post-HCT AIC. Corticosteroid and high-dose intravenous immunoglobulin achieved remission in 50% (n = 18), additional rituximab led to remission in 25% (n = 9), and the remaining 25% were treated with a combination of various modalities including sirolimus (n = 5), bortezomib (n = 3), mycophenolate mofetil (n = 2), splenectomy (n = 2), and second HCT (n = 3). The mortality of post-HCT AIC reduced from 25% (4 of 16) prior to 2011 to 5% (1 of 20) after 2011. The median follow-up of 5.8 years (range, 0.4 to 29.1 years) showed that 26 of 30 survivors (87%) were in complete remission, and 4 were in remission with ongoing sirolimus and low-dose steroids. Of the 17 who received rituximab, 7 had B-lymphocyte recovery, 5 had persistent low B-lymphocyte count and remained on intravenous immunoglobulin replacement, 2 had second HCT, and 3 died.

CONCLUSIONS

The frequency of post HCT AIC in our cohort was 9%, and the most significant risk factors for its occurrence were the presence of graft versus host disease and the use of alemtuzumab.

Fluid intake in urban China: results of the 2016 Liq.In 7 national cross-sectional surveys

Purpose

To describe total fluid intake (TFI) and types of fluid consumed in urban China by age, gender, regions and city socioeconomic status relative to the adequate intakes (AI) set by the Chinese Nutrition Society.

Methods

In 2016, participants aged 4–9, 10–17 and 18–55 years were recruited via a door-to-door approach in 27 cities in China. In total, 2233 participants were included. The volumes and sources of TFI were collected using the Liq.In⁷ record, assisted by a photographic booklet of standard fluid containers.

Results

The mean daily TFI among children, adolescents and adults were 966, 1177 and 1387 mL, respectively. In each age group, TFI was significantly higher in male vs female (981 vs 949, 1240 vs 1113, 1442 vs 1332; mL). Approximately 45, 36 and 28% of children, adolescents and adults reached the AI. Although plain water was the highest contributor to TFI, the contribution of sugar sweetened beverages (SSB) was ranked in the top three together with water and milk and derivatives. Approximately 27, 48 and 47% of children, adolescents and adults consumed more than one serving of SSB per day, respectively.

Conclusions

A relatively large proportion of participants did not drink enough to meet the AI in urban China. Many children, adolescents and adults consumed more than one serving of SSB per day. A majority of children, adolescents and adults in the study population do not meet both quantitative and qualitative fluid intake requirements, and signal socioeconomic disparities.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1755-5) contains supplementary material, which is available to authorized users.

Fluid intake of children, adolescents and adults in Indonesia: results of the 2016 Liq.In7 national cross-sectional survey

PURPOSE

To report daily total fluid intake (TFI) and fluid types in Indonesia according to age, sex, socio-economic status (SES) and geographic region, and compare TFI with the Indonesian adequate fluid intake (AI) recommendations.

METHODS

Data were collected in 32 cities over nine regions from children (4-9 years, n = 388), adolescents, (10-17 years, n = 478) and adults (18-65 years, n = 2778) using a fluid intake 7-day record (Liq.In⁷); socio-economic status was also recorded. The 7-day mean TFIs were compared with the AI of water set by the Ministry of Health of the Republic of Indonesia.

RESULTS

Total median fluid intakes for all age groups exceeded 2000 mL/day. At population level, TFI was associated with household income (P < 0.001), education (P < 0.001) and Indonesian geographical regions (P < 0.001). More than 67% of participants met the AI of water from fluids. A higher percentage of children and adolescents met the AI (78 and 80%, respectively), compared with adults (72%). Drinking water was the main contributor to TFI in all age groups (76-81%). Sugar-sweetened beverages (SSB) were consumed by 62% children, 72% adolescents and 61% of adults. An SSB intake ≥ 1 serving per day was observed for 24% children, 41% adolescents and 33% adults.

CONCLUSIONS

A high percentage of the population drank enough to meet the AI of water from fluids. Water was the most frequently consumed drink; however, many participants consumed at least one serving of SSB per day. This study provides data to help direct targeted intervention programs.

Fluid intake of Latin American children and adolescents: results of four 2016 LIQ.IN 7 National Cross-Sectional Surveys

PURPOSE

The primary aim of this survey was to report total fluid intake (TFI) and different fluid types for children (4-9 years) and adolescents (10-17 years) in Mexico, Brazil, Argentina and Uruguay. The second aim was to compare TFI with the adequate intake (AI) of water from fluids as recommended by the USA Institute of Medicine.

METHODS

Data were collected using a validated liquid intake 7-day record (Liq.In 7 ). Participants' characteristics, including age, sex and anthropometric measurements were recorded.

RESULTS

A total of 733 children and 933 adolescents were recruited. Over 75% of children in Uruguay met the IOM's recommended intake. Fewer children in Argentina (64-72%) and Brazil (41-50%) obtained AI and the lowest values were recorded in Mexico (33-44%), where 16% of boys and 14% girls drank 50% or less of the AI. More adolescents in Argentina (42%) met the AIs than other countries; the lowest was in Mexico (28%). Children and adolescents in Mexico and Argentina drank more sugar sweetened beverages than water.

CONCLUSIONS

Large numbers of children and adolescents did not meet AI recommendations for TFI, raising concerns about their hydration status and potential effects on mental and physical well-being. Given the negative effects on children's health, the levels of SSB consumption are worrying.

Fluid intake patterns of children and adolescents: results of six Liq.In7 national cross-sectional surveys

PURPOSE

This study aimed to identify and characterize patterns of fluid intake in children and adolescents from six countries: Argentina, Brazil, China, Indonesia, Mexico and Uruguay.

METHODS

Data on fluid intake volume and type amongst children (4-9 years; N = 1400) and adolescents (10-17 years; N = 1781) were collected using the validated 7-day fluid-specific record (Liq.In7 record). To identify relatively distinct clusters of subjects based on eight fluid types (water, milk and its derivatives, hot beverages, sugar-sweetened beverages (SSB), 100% fruit juices, artificial/non-nutritive sweetened beverages, alcoholic beverages, other beverages), a cluster analysis (partitioning around k-medoids algorithm) was used. Clusters were then characterized according to their socio-demographics and lifestyle indicators.

RESULTS

The six interpretable clusters identified were: low drinkers-SSB (n 523), low drinkers-water and milk (n 615), medium mixed drinkers (n 914), high drinkers-SSB (n 513), high drinkers-water (n 352) and very high drinkers-water (n 264). Country of residence was the dominant characteristic, followed by socioeconomic level, in all six patterns.

CONCLUSIONS

This analysis showed that consumption of water and SSB were the primary drivers of the clusters. In addition to country, socio-demographic and lifestyle factors played a role in determining the characteristics of each cluster. This information highlights the need to target interventions in particular populations aimed at changing fluid intake behavior and improving health in children and adolescents.

Fluid intake of Latin American adults: results of four 2016 Liq.In7 national cross-sectional surveys

Purpose

To report total fluid intake (TFI) and the intake of different fluid types in adults (≥ 18 years old) from Mexico, Argentina, Brazil and Uruguay. To compare intakes between countries and with recommended adequate intake (AI) of water from fluids.

Methods

Cross-sectional data were collected using a validated liquid intake 7-day record (Liq.In⁷) in populations from Argentina (n = 1089), Brazil (n = 477), Mexico (n = 1677) and Uruguay (n = 554). Population characteristics, including age, gender, body mass index and socioeconomic level were recorded. Mean TFI was compared with the AI of water from fluids set by the USA Institute of Medicine.

Results

The lowest TFI was recorded in Mexican women (1748 mL/day) and the highest in Argentinean men (2318 mL/day). Median daily TFI was significantly different between countries; Uruguay and Argentina had higher values than Mexico and Brazil. In the former, plain water contributed to only 25% of TFI, the remainder being predominantly from hot beverages. Approximately, a third of adults did not drink enough fluid to meet the recommended AI. High SSB consumption was reported, which was significantly different between countries (p < 0.05), the highest being in Mexico (median 25–75th percentiles): 531 (300–895 mL/day.

Conclusions

This survey highlights the need to increase water consumption and reduce SSB intake in this region to avoid potential associated health risks. These findings may be useful information in monitoring public health policy strategies.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1724-z) contains supplementary material, which is available to authorized users.

A comparison of drinking behavior using a harmonized methodology (Liq.In 7 ) in six countries

PURPOSE

To assess drinking occasions (volume and type) according to consumption with food in or outside meals, and location, for six countries.

METHODS

A total of 10,521 participants aged 4-65 years from Argentina, Brazil, China, Indonesia, Mexico and Uruguay completed a validated 7-day fluid intake record. For each drinking event, the volume consumed, the fluid type, the location of intake, and whether the drink was accompanied by food (meal or snack) or not, was recorded.

RESULTS

Similar drinking behaviors were found in Mexico and Argentina; fluid intake during meals was 48 and 45% of total fluid intake (TFI), respectively. In Brazil (55%), Indonesia (58%) and China (66%) most fluid was consumed without food. In Uruguay, 34% of TFI was with a main meal, 31% with food between meals and 35% without food. Indonesia had the highest median (25-75th percentile) TFI; 2520 (1750-3347) mL/day, and China the lowest 1138 (818-3347) mL/day. Water was consumed with meals for 37% of Chinese and 87% of Indonesian participants, while the four Latin-American American countries showed a preference for sweet drinks; 54% in Mexico, 67% in Brazil, 55% in Argentina and 59% in Uruguay. Diversity in fluid type was noted when drinking with food between meals. Apart from China, most drinking occasions (> 75%) occurred at home.

CONCLUSIONS

Three distinct drinking behaviors were identified, namely, drinking with meals, drinking as a stand-alone activity, and a type of 'grazing' (i.e., frequent drinks throughout the day) behavior. Most drinking occasions occurred at home.

Secukinumab in the Treatment of Psoriasis and Psoriatic Arthritis: A Review of the Literature

While there are several commercially available treatment options for psoriasis and psoriatic arthritis, there remains a large number of individuals who are refractory to current modalities. In the recent past, there has been increasing evidence that interleukin (IL)-17 plays a vital role in the pathophysiology of psoriasis. Preclinical, phase II, and phase III studies of secukinumab (Cosentyx®) targeting IL-17 and its receptor have thus far proved to be promising. We reviewed the results of phase II and phase III clinical trials for secukinumab in the treatment of psoriasis and psoriatic arthritis. Only published studies were considered in the present review. We also performed an English language literature search from January 2003 to September 2015 using PubMed with any of the following key words: (secukinumab OR AIN457) AND (psoriasis OR psoriatic arthritis). In our review of the literature, seven phase III and five phase II clinical trials, as well as open-label extension studies with unpublished findings were found. Results from phase III clinical trials indicated secukinumab to be efficacious and safe for the treatment of psoriasis and psoriatic arthritis according to Psoriasis Area and Severity Index (PASI) and American College of Rheumatology (ACR) scores. The safety profile of this agent was similar across all studies, with the most frequently reported adverse events of nasopharyngitis, upper respiratory infections, headache, and injection site reaction. Secukinumab demonstrates rapid and robust clinical improvement accompanied by a favorable short- term safety profile. The results of the phase III trials continue to reinforce the theory that the IL-17 pathway is an essential target in psoriasis and psoriatic arthritis treatment. Additional extension studies of lower level evidence are needed to further understand the safety profile of the drug.

Hydration education: developing, piloting and evaluating a hydration education package for general practitioners

OBJECTIVES

To (1) assess the hydration knowledge, attitudes and practices (KAP) of doctors; (2) develop an evidence-based training package; and (3) evaluate the impact of the training package.

DESIGN

Educational intervention with impact evaluation.

SETTING

Cambridgeshire, UK.

PARTICIPANTS

General practitioners (GPs (primary care physicians)).

INTERVENTIONS

Hydration and healthcare training.

MAIN OUTCOME MEASURES

Hydration KAP score before and immediately after the training session.

RESULTS

Knowledge gaps of doctors identified before the teaching were the definition of dehydration, European Food Safety Authority water intake recommendations, water content of the human body and proportion of water from food and drink. A face-to-face teaching package was developed on findings from the KAP survey and literature search. 54 questionnaires were completed before and immediately after two training sessions with GPs. Following the training, total hydration KAP scores increased significantly (p<0.001; median (25th, 75th centiles); 32 (29, 34)). Attendees rated the session as excellent or good (90%) and reported the training was likely to influence their professional practice (100%).

CONCLUSIONS

The training package will continue to be developed and adapted, with increased focus on follow-up strategies as well as integration into medical curricula and standards of practice. However, further research is required in the area of hydration care to allow policymakers to incorporate hydration awareness and care with greater precision in local and national policies.

Intake of water and different beverages in adults across 13 countries

Purpose

To describe the intake of water and all other fluids and to evaluate the proportion of adults exceeding the World Health Organisation (WHO) recommendations on energy intake from free sugar, solely from fluids.

Methods

A total of 16,276 adults (46 % men, mean age 39.8 years) were recruited in 13 countries from 3 continents. A 24-h fluid-specific record over 7 days was used for fluid assessment.

Results

In Spain, France, Turkey, Iran, Indonesia and China, fluid intake was characterised by a high contribution of water (47–78 %) to total fluid intake (TFI), with a mean water intake between 0.76 and 1.78 L/day, and a mean energy intake from fluids from 182 to 428 kcal/day. Between 11 and 49 % of adults exceeded the free sugar WHO recommendations, considering solely fluids. In Germany, UK, Poland and Japan, the largest contributors to TFI were hot beverages (28–50 %) and water (18–32 %). Mean energy intake from fluids ranged from 415 to 817 kcal/day, and 48–62 % of adults exceeded free sugar WHO recommendations. In Mexico, Brazil and Argentina, the contribution of juices and regular sugar beverages (28–41 %) was as important as the water contribution to TFI (17–39 %). Mean energy intake from fluids ranged 565–694 kcal/day, and 60–66 % of the adults exceeded the free sugar WHO recommendation.

Conclusions

The highest volumes recorded in most of the countries were for water, mean energy intake from fluids was up to 694 kcal/day, and 66 % of adults exceeded the free sugar WHO recommendation solely by fluids. Actions to create an environment in favour of water consumption and reduce sugar intake from fluids therefore are warranted.

Electronic supplementary material

The online version of this article (doi:10.1007/s00394-015-0952-8) contains supplementary material, which is available to authorized users.

Nonesterified fatty acids modify inflammatory response and eicosanoid biosynthesis in bovine endothelial cells

Intense lipid mobilization during the transition period in dairy cows is associated with increased disease susceptibility. The potential impact of altered plasma nonesterified fatty acids (NEFA) concentrations and composition on host inflammatory responses that may contribute to disease incidence and severity are not known. The objective of this study was to evaluate if increased NEFA concentrations could modify vascular inflammatory responses in vitro by changing the expression of important inflammatory mediators that are important in the pathogenesis of infectious diseases of transition cows such as mastitis and metritis. Bovine aortic endothelial cells (BAEC) were cultured with different concentrations of a NEFA mixture that reflected the plasma NEFA composition during different stages of lactation. The expression of cytokines, adhesion molecules, and eicosanoids were measured to assess changes in BAEC inflammatory phenotype. Addition of NEFA mixtures altered the fatty acid profile of BAEC by increasing the concentration of stearic acid (C18:0) and decreasing the content of arachidonic acid (C20:4n6c) and other long-chain polyunsaturated fatty acids in the phospholipid fraction. A significant increase also occurred in mRNA expression of cytokine and adhesion molecules that are associated with increased inflammatory responses during the transition period. Expression of cyclooxygenase 2, an important enzyme associated with eicosanoid biosynthesis, was increased in a NEFA concentration-dependent manner. The production of linoleic acid-derived eicosanoids 9- and 13-hydroxyoctadecadienoic acids also was increased significantly after treatment with NEFA mixtures. This research described for the first time specific changes in vascular inflammatory response during in vitro exposure to NEFA mixtures that mimic the composition and concentration found in cows during the transition period. These findings could explain, in part, alterations in inflammatory responses observed during intense lipid mobilization stages such as in the transition period of dairy cows. Future studies should analyze specific mechanisms by which high NEFA concentrations induce a vascular proinflammatory phenotype including the effect of 9 and 13-hydroxyoctadecadienoic acids and other lipid mediators.

An exploration of factors that influence the regular consumption of water by Irish primary school children

BACKGROUND

Inadequate hydration has been linked to many factors that may impact on children's education and health. Teachers play an important role in the education and behaviour of children. Previous research has demonstrated low water intake amongst children and negative teachers' attitudes to water in the classroom. The present study aimed to explore teachers' knowledge about water and the perceived barriers to allowing children access to water during lesson time.

METHODS

In-depth interviews were conducted with 12 teachers from primary schools in the Midlands of Ireland. Interviews were continued until there was saturation of the data. Thematic analysis of the data was conducted.

RESULTS

Participants had a poor knowledge of hydration requirements and the associated health benefits and effect on concentration. Low water intake amongst teachers and pupils, and barriers such as disruption to class and increased need to urinate, were reported. Teachers identified the hydration effect on learning as the education message most likely to influence the decision to allow water in the classroom.

CONCLUSIONS

The issues, opinions and perceived barriers raised by teachers as part of this qualitative research provide a basis for future health promotion around water.

Determining the transrepression activity of xenoestrogen on nuclear factor-kappa B in Cos-1 cells by estrogen receptor-alpha

Functional assays have been used to define the estrogenicity of xenoestrogens in cotransfection studies employing estrogen receptors in various cell lines. It is known that estrogen is able to affect transcription from other nuclear transcription factors, especially the nuclear factor-kappa B (NF-kappa B). The ability of selected xenoestrogens (methoxychlor [MXC], dieldrin, and o',p'-DDT) to transrepress the NF-kappa B-mediated transcription in Cos-1 cells was evaluated by cotransfection of human estrogen receptor-alpha (hERalpha). These xenoestrogens have been described as comparably potent xenoestrogens, whereas their relative binding activity (RBA) has been relegated to a lower order as compare to estrogen. The two NF-kappa B response element-containing SV40 promoter and -242/+54 cytomegalovirus (CMV)-expressing firefly luciferase (2 x NRE-PV-Luc and 2 x NRE-CMV-Luc, respectively) were transfected into Cos-1 cells with pRL-tk, expressing the renilla luciferase as internal control. The estrogen receptor was expressed from cytomegalovirus major immediate early promoter (CMV-MIEP) (CMV5-hERalpha). Treatment with 1 nM estrogen (E(2)) (26.2%), 5 nM E(2) (41.4%; p < .05), and xenoestrogens (methoxychlor [1 nM: 29.6%, p < .05; 10 nM: 22.6%), dieldrin [1 nM: 10.3%; 10 nM: 36.06%, p < .05], and o',p'-DDT [1 nM: 17.0%; 10 nM: 7.15%]) repressed transcription from 2 x NREX-PV-Luc. The antiestrogen, ICI 182,780, failed to antagonize the effects of xenoestrogens. The effects of xenoestrogens in transrepression of NF-kappa B by ERalpha were similar when 2 x NRE-CMV-Luc was employed as reporter. Statistically significant (p < .01) repression by 1 nM E(2) (69.2%), 5 nM E(2) (69.1%), 1 nM o',p'-DDT (51.4%), 1 nM dieldrin (47.3%), and 1 nM MXC (73.3%) were observed. The effect of these xenoestrogens without ERalpha cotransfection on 2 x NRE-PV-Luc- and 2 x NRE-CMV-Luc-mediated NF-kappa B transcription was not affected by the treatment alone. It is concluded that xenoestrogens, like estrogens, are capable of producing transrepression of NF-kappa B by hERalpha.

Propanil (3,4-dichloropropionanilide) particulate concentrations within and near the residences of families living adjacent to aerially sprayed rice fields

Propanil is widely used as a postemergence herbicide in rice. Because it is typically applied aerially, there is a potential for propanil to drift into and around homes of those living adjacent to rice fields. Propanil has been shown to be immunotoxic in rodent models. The objective of this study was to measure the levels of propanil to which families living adjacent to aerially sprayed rice fields may be exposed. Air levels were sampled by actively and passively collecting propanil in and around the homes of volunteer families living in close proximity to rice fields sprayed with propanil. Homes ranged from 73 m to 113 m from treated rice fields. Sampling was conducted in the home, adjacent to the home (within 5 m of the home), 30 m from the home, and at the edge of the rice field. Concentrations were determined via gas chromatography/mass spectroscopy. Propanil levels adjacent to the homes ranged from nondetectable to 1,106.4 microg per 400 cm2 collection surface (2.0 microg detection limit). Wind direction and wind velocity were the primary determinants of propanil drift. At sites where the prevailing wind was blowing away from the home, no propanil was detected except at the edge of the field. Distance from the edge of the rice field also influenced the amount of drift with higher levels measured at 30 m from the house than adjacent to the house. No propanil vapor was detected on absorbent media sampled in and around the homes. The results indicate that individuals living adjacent to rice fields aerially sprayed with propanil are potentially exposed to variable amounts of propanil, and wind speed and direction are the most important factors that influence the concentration of aerially applied pesticide.

Evaluation of immune parameters in propanil-exposed farm families

The rice herbicide propanil induces alterations in the mouse immune system, causing significant decreases in T cell-dependent and T cell-independent antibody responses. This postemergent herbicide is used extensively in rice production in the Mississippi River delta region of the southern United States. The aerial application and airborne drift of propanil may pose health concerns to exposed farm families living adjacent to sprayed rice fields. To determine if aerial spraying of propanil increases risks of altered immune responses in families bordering rice fields, immune parameters were assessed during a 2-year study. Families living within 100 yards of rice fields were compared in a case control study to farm families whose homes exceeded 1 mile from any rice field. Blood was analyzed in adults (n = 56) and children (n = 52) at three time intervals: (1) preseason, prior to propanil application; (2) 5-7 days after aerial application of propanil to rice fields; and (3) postseason, following harvest. Exposed adults and children were compared with controls for a number of immune parameters. Total cell count and the percentage of various lymphocytes (T cells, B cells, CD4+ helper cells, and CD8+ suppressor cells) and natural killer (NK) cells, mitogen-induced cell proliferation, cytokine (IL-2+) production, and NK cell function were assessed. A comparison of immune function between exposed and nonexposed farm families showed no significant differences, possibly related to propanil exposure. However, some immune test parameters changed as a function of season rather than propanil exposure. The data indicate that individuals living next to rice fields are not at increased risk of altered immune function due to propanil exposure.

Perkinsus marinus tissue distribution and seasonal variation in oysters Crassostrea virginica from Florida, Virginia and New York

Perkinsus marinus infection intensity was measured in eastern oysters Crassostrea virginica collected in October and December 1993, and March, May, and July 1994 from 3 U.S. sites: Apalachicola Bay (FL), Chesapeake Bay (VA), and Oyster Bay (NY). Gill, mantle, digestive gland, adductor muscle, hemolymph, and remaining tissue (including gonadal material and rectum) were dissected from 20 oysters from each site at each collection time. Samples were separately diagnosed for P. marinus infections by incubation in Ray's Fluid Thioglycollate Medium (RFTM) and subsequent microscopic quantification of purified enlarged hypnospores. At all sampling times and sites, average P. marinus infection intensity (g wet wt tissue-1 or ml hemolymph-1) was lowest in hemolymph samples, and generally highest in the digestive gland. Perkinsus marinus prevalence was 100% at both FL and NY sites for each of the 5 collection times, and, for the VA site, was less than 100% in only 1 month (May 1994). Seasonal intensity patterns and mean total body burdens differed among the sites. Average body burden was highest in VA during October and progressively declined to a minimum in May. This decline was probably due to mortality of heavily infected oysters and diminution of parasite activity associated with colder temperatures and reduced salinities. Intensities varied little during the months of October and December at both the FL and NY sites. Minimum average intensities were observed in March in FL oysters and May in NY oysters. Relatively high P. marinus infection levels that persisted throughout the winter in NY oysters compared with VA oysters could reflect constant high salinity in Long Island Sound which favors parasite activity, and also rapid decline in temperature in the fall that may have prevented epizootic oyster mortalities.

Risks of intravenous amiodarone in neonates

The courses of two neonates treated with intravenous amiodarone for supraventricular tachyarrhythmia, both of whom developed significant adverse effects, are reported. A 13-day-old term newborn developed hypothyroidism after 27 days of mostly intravenous amiodarone for atrioventricular reciprocating tachycardia and severe heart failure. A one-day-old, 36 weeks' gestation newborn developed electromechanical dissociation after receiving an intravenous bolus of amiodarone for rapid atrial flutter. Judicious use of amiodarone is recommended.

Endocrine mechanisms underlying reproductive toxicity in the developing rat chronically exposed to dietary lead

A dose-response study was conducted in a rat model to examine the effects of lifetime lead exposure on the development of the reproductive system and the endocrine mechanisms underlying these effects. Time-impregnated female Sprague-Dawley rats (n = 10-15/group) were exposed to lead acetate in the drinking water at levels of 0.05%, 0. 15%, or 0.45% (w/v) initiated on gestational day 5. At birth, litters were culled to four male and four female pups. Exposure of dams to lead was continued until weaning, following which, the pups continued to be exposed to lead acetate in drinking water until sacrifice. One male and one female pup from each litter were sacrificed at age 21, 35, 55, and 85 d. A significant dose-responsive decrease in birth weight and crown-to-rump length was observed in all lead-exposed litters. However, no marked effects were observed on anogenital distance/crown-to-rump length ratios. Lead exposure resulted in a delay in sexual maturity as measured by prostate weight in male pups and time of vaginal opening in female pups, which increased with lead dose. These disruptions in reproductive physiology were accompanied by a significant decrease in neonatal sex steroid levels and suppression of the plasma concentrations of testosterone (male) and estradiol (female) during puberty. In male pups, this was accompanied by a significant decrease in plasma luteinizing hormone (LH), elevated pituitary LH content, and a decrease in plasma testosterone/LH ratios at the highest dose. In female pups, although no effects were observed on plasma LH concentration, a similar significant elevation in pituitary LH content was observed during early puberty. Postpuberty, plasma LH and sex steroid concentrations were unaffected at any dose in spite of continued lead exposure. No significant effects were observed on epididymal sperm count in male pups at 85 d of age. In female pups, estrus cycling was only significantly disrupted at the highest lead dose. These data suggest that the reproductive axis is particularly sensitive to lead during specific developmental periods, resulting in delayed sexual maturation produced by suppression by sex steroid biosynthesis. The mechanisms underlying this appear to involve lead actions on both LH release and gonadal function. At low, environmentally relevant blood lead concentrations, adaptation to the continuous presence of the metal ion occurs and surprisingly little effect is observed on adult reproductive endocrinology and physiology.

Neonatal Meckel's diverticular inflammation with perforation

Meckel's diverticulum occurs in approximately 2% of the general population and is usually asymptomatic. Four percent of cases will present as an acute abdomen caused by intestinal obstruction, gastrointestinal bleeding, and inflammation. A neonatal presentation of Meckel's diverticulum mimicking necrotizing enterocolitis is described.

Effects of caloric restriction on expression of testicular cytochrome P450 enzymes associated with the metabolic activation of carcinogens

Previous work demonstrated that microsomal cytochrome P4502A1 (CYP2A1) is expressed in rat testicular Leydig cells. The present study investigates the effects of diet, age, and strain on rat testicular CYP2A1 expression and assesses the potential role of testicular CYP2A1 in the metabolic activation of carcinogens. In ad libitum-fed 18-week-old Fischer 344 rats, testicular CYP2A1 immunoreactive protein and testosterone 7alpha-hydroxylase activity (7alpha-TOHase) exhibited a circadian variation with a daytime maximum and a night-time minimum (82.2 +/- 42.0 and 21.9 +/- 4.5 pmol 7alpha-hydroxytestosterone/min/mg protein, respectively). Caloric restriction (to 60% of ad libitum consumption), which reduces the severity of Leydig cell tumors in rats, decreased expression of both CYP2A1 and testicular 7alpha-TOHase >80% and eliminated their circadian variation. Conversely, caloric restriction induced a circadian rhythm in testicular 7-benzyloxyresorufin-O-dealkylase activity. Testicular microsomes from ad libitum-fed rats having peak diurnal 7alpha-TOHase activity had significantly greater (30%) microsome-mediated aflatoxin B1-DNA binding activity compared to microsomes prepared from nocturnal phase ad libitum-fed or calorically restricted rats which expressed low 7alpha-TOHase activity. In 12-month-old Fischer 344 rats, high CYP2A1 expression was correlated with severe Leydig cell hyperplasia (r = 0.80), whereas CYP2A immunoreactive protein and 7alpha-TOHase were expressed at lower levels in Sprague-Dawley than in Fischer 344 rats and were undetectable in pig, monkey, and human testes. These are strains/species that do not exhibit significant Leydig cell hyperplasia. This suggests that caloric intake, strain, and circadian factors may all mediate testicular CYP2A1 expression in the rat and that CYP2A1 may in turn influence carcinogen activation and pathological status in the testis.

Differential expression of glutathione S-transferase isoforms in compartments of the testis and segments of the epididymis of the rat

Specific cell types of the mammalian testes demonstrate varying susceptibility to toxic insult by chemical agents. The mammalian testis is divided into two major compartments: seminiferous tubules, the site of spermatogenesis, and interstitium, which contains the Leydig cells. Glutathione S-transferase (GST) expression was examined in isolated compartments of the rat testis and in segments of the epididymis. Western blot analysis revealed the presence of GST class alpha, mu, and pi bands in each of the isolated compartments of the testis, and HPLC analysis of monomeric isoforms provided evidence for differential expression of multiple GST isoforms in testicular compartments. All major isoforms (e.g., forms 1, 2, 3, 4, 6, 7, 8, 9, and 11) were detected in the cytosol of whole testis. Isoform subunit 4 was the major form in the tubule, whereas isoform subunit 11 is the dominant form in the Leydig cells. Isoform subunits 3, 4, and 6 were enriched in the tubules as compared to interstitial or Leydig cells. The preferential action of reproductive toxicants at specific stages of aging may be due to an age-dependent expression of the activating or detoxifying enzymes in the reproductive tract. Therefore, the age-dependent expression of testicular GST isoforms was also examined. Expression of isoform subunits 2 and 4 displayed an age dependence, with the largest increase in these subunits occurring between ages 4 and 15 weeks. Isoform expression did not correlate with serum testosterone levels. HPLC analysis of the GST isoforms in the longitudinal segments of the epididymis and vas deferens revealed differential expression within these segments. Total GST protein and catalytic activity was highest in the caput epididymis and progressively decreased toward the vas deferens. Isoform subunit 2 was the major form expressed in the epididymis. The results of this study indicate that the GSTs are differentially expressed in testicular compartments and epididymal segments, and that this may contribute to susceptibility of different cell types to xenobiotic damage.

Changes in primary and secondary lymphoid organ T-cell subpopulations resulting from acute in vivo exposure to propanil

Acute exposure to the herbicide propanil is immunotoxic for selected immune functions, as well as causing changes in the weights of the thymus and spleen. Although spleen cellularity and weight increase with propanil exposure, the thymus: body weight ratio decreases with increasing doses of propanil. The present study analyzes the thymocyte subpopulations in the thymus, spleen, and mesenteric lymph nodes. C57Bl/6 mice were treated with either 0, 100, 150, or 200 mg/kg propanil, and 7 d later thymocyte populations were analyzed by flow cytometry. In the thymus, propanil exposure resulted in a dose-dependent decrease in total numbers of T cells, as would be expected with its reduced weight. Determination of the thymocyte subpopulation distribution in the thymus showed a significant reduction in the number of CD3+CD4+CD8- (CD3+4+8-), CD3+CD4-CD8+ (CD3+4-8+), and CD3+CD4+CD8+ (CD3+4+8+) cells. Percent distribution of these thymic cell subpopulations showed similar decreases only with the highest dose. Apparent dose-related decreases in the numbers of CD3-CD4+CD8+ (CD3-4+8+) cells were also noted and were attributed to the general decrease in total thymus cells. The percentage of CD3- subpopulations showed an increasing trend with dose, which suggests that at 7 d postpropanil exposure there may be a specific effect on this most immature population. Although the size and cellularity of the spleen were increased, no change in CD4+ or CD8+ cell distribution was observed. Similarly, mesenteric lymph nodes showed no changes in the cell subpopulation distribution between propanil-treated and control animals.

X-ray evidence that in contracting live frog muscles there exist two distinct populations of myosin heads

Using synchrotron radiation and whole muscles, 2 ms time-resolved x-ray diffraction patterns were recorded at 8 degrees C. The results show that in both isotonic and isometric contractions, as well as in length changes imposed at maximum tension [Po], the meridional third myosin layer line consists of two distinct reflections with different intensities and spacings that measure approximately 14,623 and 14,412 nm at Po. Although the intensity behavior of the two reflections is strikingly different during quick releases, it is very similar during stretches. Study of the time courses indicates that myosin heads diffracting at Po with the approximately 14.623 nm periodicity are actively involved in tension production. Those diffracting at Po with the periodicity of approximately 14.412 nm appear not be associated with tension production during isometric contraction and releases, but the results suggest that they are recruited during stretches and here contribute to tension production. Our most important conclusion is that under all conditions of contraction we have investigated there exist two populations of myosin heads, each with a well defined axial disposition and configuration.

Selective myelotoxicity of propanil

Propanil, a commonly used herbicide, has been previously shown to be immunotoxic for selected immune functions as well as specific cell types, such as the macrophage. Propanil has also been shown to cause a methemoglobulinemia and anemia through direct action on the erythrocyte. Demonstrated toxicity to both macrophages and erythrocytes raised concern for the possible myelotoxicity of propanil which could contribute to the observed effects of exposure. Therefore, the effect of propanil on several stem and progenitor cell types was assessed 7 days after acute propanil exposure. The results described herein show that propanil, at doses of 50-200 mg/kg body wt, resulted in reduction in the number of myeloid stem cells and early myeloid and erythroid progenitor cells. No reduction in the numbers of more differentiated myeloid and erythroid progenitor cells was noted at even the highest dose used (200 mg/kg). In addition, no statistically significant difference in number of leukocytes per femur was noted. These data suggest that propanil is myelotoxic to early hemapoietic stem cells, but that this reduction is apparently compensated by proliferation of more differentiated progenitor cells for the myeloid and erythroid lineages. It remains unknown whether chronic exposure leads to progressive depletion of additional myeloid and erythroid cells.

Glutathione depletion potentiates ethyl methanesulfonate-induced damage to sperm chromatin structure

Male rats were treated with phorone at dosages previously shown to reduce glutathione in rodent reproductive tracts, followed by a single challenge with ethyl methanesulfonate, a known mutagenic and clastogenic agent. Epididymal sperm collected 8 and 15 days after exposure from phorone pretreated animals had a significantly greater alteration of sperm chromatin structure, defined as an increased susceptibility to DNA denaturation in situ, relative to sperm obtained from animals injected with saline alone or saline+EMS (50, 100, 150, or 200 mg/kg bw). These data support the hypothesis that ethyl methanesulfonate-induced alkylation of developing sperm chromatin protamines causes a significant stress on chromatin structure leading to increased DNA damage. This is the first report showing that glutathione depletion potentiates EMS-induced chromatin structural alterations that are likely related to dominant lethal mutations.

Enhanced glutathione S-transferase 7-7 expression in rat hepatic cytosol following treatment with pyrrole

Rat hepatic GST 7-7 expression in cytosol and in the S-hexylglutathione-agarose affinity purified fraction of cytosol from saline- (control) and pyrrole-treated animals was examined using metabolic activity, SDS-PAGE, immunoblot, and HPLC analyses. Metabolic activity of hepatic cytosol from pyrrole-treated animals was assayed using the substrates 1-chloro-2,4-dinitrobenzene, ethacrynic acid, and acrolein, and an approximately 1.5-, 1.2-, and 1.3-fold increase, respectively, was monitored in the rate of GST-catalyzed substrate conjugation to reduced glutathione. SDS-PAGE and immunoblot analysis using Class Pi GST-specific IgG confirmed that the GST 7 subunit was expressed in hepatic cytosol and in the affinity purified fractions from pyrrole-treated rats. In contrast, the GST 7 subunit was below the limit of detection in hepatic cytosol of saline-treated animals. HPLC analysis demonstrated the presence of the GST 7 subunit in the affinity purified fraction from pyrrole-treated rat hepatic tissue and showed that the level of this subunit was increased approximately 8-fold relative to the barely detectable level present in control tissue. N-terminal amino acid sequencing analysis confirmed the identity of the HPLC peak as GST 7-7. GST subunits 3, 1a, and 1b were elevated approximately 1.7-, 2.0-, and 2.4-fold respectively, in response to pyrrole treatment. These data provide evidence that pyrrole treatment results in de novo expression of GST 7-7 in rat hepatic tissue and suggest that pyrrole-containing compounds potentially generated during disease and/or altered heme metabolism, or those ingested in food products, may alter GST expression in hepatic tissue.

Alteration of macrophage cytotoxicity through endogenous interferon and tumor necrosis factor alpha induction by propanil

The effect of propanil on mouse peritoneal macrophages (m phi) was measured by determining cytotoxicity via the P815 cell line, which is resistant to tumor necrosis factor alpha (TNF-alpha). Although control animals showed a typical pattern of requiring both interferon (IFN)-gamma and lipopolysaccharide (LPS) for m phi activation, m phi from propanil-treated animals were cytotoxic when induced with LPS alone. This suggested that propanil influenced endogenous IFN levels. This was confirmed by the abrogation of cytotoxicity upon addition of anti-IFN to the cultures. When cells were assayed for IFN transcript, mRNA in resident m phi was present in higher concentrations in propanil-treated animals. IFN mRNA was present in even higher concentrations in m phi from propanil-treated animals after 30 min of culture with LPS, whereas control m phi required 4 hr in culture with LPS to produce similar levels. IFN protein levels were also higher in propanil-treated m phi after culture in the presence of LPS. Thus, propanil induces increased levels of endogenous IFN which probably works in conjunction with LPS to induce P815 cytotoxicity. Because of the known influence IFN has on the increased secretion of TNF-alpha, we tested the tumoricidal activity of m phi from propanil-treated animals against TNF-alpha-sensitive cell lines. When using WEHI-164 or L929 cells, m phi from propanil-treated animals revealed tumoricidal activity with just the addition of LPS or IFN-gamma. This implies that the additional endogenous levels of IFN, combined with other propanil-induced effects, caused increased secretion of TNF-alpha from m phi.

Comparison of the immunotoxicity of propanil and its metabolite, 3,4-dichloroaniline, in C57Bl/6 mice

Propanil (3,4-dichloropropionaniline), used extensively as a postemergence herbicide in rice and wheat, has as its major metabolite, 3,4-dichloroaniline (DCA). Propanil has previously been shown to affect the T cell-dependent antibody response. To determine the immunotoxicity of DCA, as well as extend the previous immunotoxicity studies, several T cell-dependent and -independent immune responses were determined after DCA or propanil exposure. Unlike propanil, DCA caused a significant reduction in T-dependent antibody production (anti-SRBC response) only at a high dose (150 mg/kg). DCA or propanil at 150 or 200 mg/kg, respectively, caused a significant reduction in the number of anti-DNP antibody producing cells. However, doses of 37 or 50 mg/kg of DCA or propanil, respectively, caused an increase in the number of anti-DNP antibody producing cells. These data indicate that both propanil and DCA have a differential effect on the T-independent antibody response depending on the dose. Similar to propanil, DCA (at 150 mg/kg) caused a significant increase in spleen weight and cellularity. The effect of DCA or propanil on selected cellular immune functions was also determined. DCA caused a significant decrease in the natural killer (NK) cell activity at doses of 75 or 150 mg/kg, and propanil caused a significant decrease at 100 or 200 mg/kg. Cytotoxic T lymphocyte activity, however, was unaffected even at 150 or 200 mg/kg DCA or propanil, respectively. Thus, it appears that T cells are relatively resistant to the effects of propanil and DCA, whereas, other immune cell types, e.g., NK cells are sensitive to its effects.

Effects of reproductive tract glutathione enhancement and depletion on ethyl methanesulfonate-induced dominant lethal mutations in Sprague-Dawley rats

The effects of altering glutathione (GSH) levels in the male reproductive tract have been studied in an attempt to establish a link between chemical-induced perturbations in glutathione and susceptibility of spermatozoa to chemical insult. Tissue GSH levels were enhanced by a treatment regimen of N-acetylcysteine (NAC) (250 mg/kg, 4 treatments at 2 h intervals). With this treatment, GSH levels in liver, testis, caput epididymis, and cauda epididymis were elevated to 126%, 110%, 178%, and 136% of control values. Sexually mature male rats were then treated with NAC and challenged with a dose of EMS (100 mg/kg) to determine if enhanced tissue GSH would protect against EMS-induced dominant lethal mutations. Pretreatment with NAC significantly decreased the post-implantation loss from 7.05 +/- 0.57 with EMS alone to 5.28 +/- 0.47. Conversely, a dominant lethal assay was conducted using different doses of phorone pretreatment to determine the relative contribution of hepatic versus reproductive tract GSH in protecting against EMS-induced dominant lethal resorptions. Doses of 100 mg/kg and 250 mg/kg phorone significantly lowered both hepatic and reproductive tract GSH while 25 mg/kg lowered only hepatic GSH. These three dose levels were used as pretreatments in a dominant lethal study followed by a challenge administration of EMS (50 mg/kg), which is a threshold dose of EMS for producing dominant lethal mutations. Comparison against controls demonstrated a significant potentiation of fetal resorptions in all groups receiving phorone pretreatment, including the 25 mg/kg pretreatment group which only lowered hepatic GSH prior to EMS challenge. The results of these experiments indicate that GSH reserves in the male reproductive tract are insufficient to protect developing spermatozoa from damage by alkylating agents in the absence of hepatic GSH.

Cellular localization of cytochrome P450IIA1 in testes of mature Sprague-Dawley rats

Previous studies have shown that a prominent site of extrahepatic cytochrome P450IIA1 in male rats is the testis. We investigated the cellular location of cytochrome P450IIA1 in the testes of adult rats. Using specific isolation of testicular compartments and individual cell types, as well as in vivo removal of Leydig cells by ethane dimethyl sulfonate, we determined the cellular location of cytochrome P450IIA1 using testosterone hydroxylation assay, Western immunoblotting, and immunohistochemical analysis. Enriched Leydig cell fractions had the greatest testosterone 7 alpha-hydroxylase activity as well as immunoreactivity. Immunohistochemical analysis confirmed that the cellular location of cytochrome P450IIA1 was specific to Leydig cells. The specific localization of enzyme systems that are involved in xenobiotic activation may have important implications for inducing specific cell toxicity by compounds that exert their effects in the testes.

Alteration of fetal liver colony formation by prenatal chlordane exposure

Female mice were treated with 0 or 8 mg/kg chlordane daily for 18 days during pregnancy. The fetuses of these mice were assayed for fetal liver hematopoietic activity at 18 days gestational age. Hematopoietic activity was evaluated for in vitro granulocyte-macrophage colony-forming units (GM-CFU) and in vivo spleen CFU (CFU-S). The consistent finding was a significant depression of the numbers of both fetal liver GM-CFU and CFU-S without a change in liver cellularity in fetuses exposed to 8 mg/kg chlordane. These data show that the damage to stem cells that persists into adult life as a result of chlordane exposure, as reported earlier by Barnett et al. (1990) Fundam. Appl. Toxicol. 14, 688-695, occurred during the fetal period.

Effect of general anaesthesia on whole body protein turnover in patients undergoing elective surgery

To determine if general anaesthesia alone or in conjunction with surgery alters body protein turnover, we studied six healthy, unpremedicated females undergoing elective total abdominal hysterectomy. Changes in protein metabolism, synthesis and breakdown were estimated by an isotope dilution technique using a continuous infusion of the stable isotope tracer, L-[1-13C]leucine, before anaesthesia (4 h), during anaesthesia alone (1 h), during anaesthesia and surgery (1 h) and in the recovery period (2 h). General anaesthesia comprised thiopentone, pancuronium, enflurane (1 MAC) and oxygen-enriched air. An isotopic steady state in plasma 13C-alpha-ketoisocaproate (13C alpha-KIC) and expired 13C-carbon dioxide were obtained during the four periods. Collections of plasma and expired air were made during the steady state periods and plasma alpha-KIC enrichment measured to indicate precursor pool labelling from which leucine flux (equal to protein breakdown in the post-absorptive state) and oxidation were calculated, and whole body protein synthesis was derived. Whole body protein breakdown did not change with anaesthesia, but decreased with both surgery and during the acute recovery period (P less than 0.05). Protein synthesis did not change with anaesthesia and surgery, but decreased significantly after surgery (P less than 0.05).

Long-term alteration of adult bone marrow colony formation by prenatal chlordane exposure

Female mice were treated with either 0, 4, or 8 mg of chlordane per kilogram body weight daily for 18 days during pregnancy. The offspring of these mice were assayed for bone marrow hematopoietic activity at 100 and 200 days of age. Hematopoietic activity was evaluated for in vitro granulocyte-macrophage colony-forming units (GM-CFU) and in vivo spleen CFU (CFU-S). The consistent finding was a significant depression both of the numbers of bone marrow GM-CFU and of the CFU-S in offspring exposed to either 4 or 8 mg/kg chlordane even at 100 and 200 days after cessation of treatment. Prenatal treatment with chlordane did not affect the number of recoverable viable bone marrow cells at either of these time points. Ontological development was selectively affected by chlordane exposure, since subchronic (18 day) treatment of adult mice did not significantly alter bone marrow GM-CFU or CFU-S levels. These data suggest that the decreased delayed-type hypersensitivity reactions noted previously in mice exposed to chlordane prenatally may be due to a change in the functional capacity of myeloid lineage cells rather than altered T cell function.

Cytotoxic T-lymphocyte and NK responses in mice treated prenatally with chlordane

It has been reported previously that BALB/c mice, treated in utero with chlordane, showed increased survival to influenza A/PR/8/34 [H1N1] (influenza) virus as young adults. To determine the possible role of cell-mediated immunity (CMI) on this effect, cytotoxic T-lymphocyte (CTL) and natural killer (NK) cell activities were assessed on chlordane-exposed offspring at 100 and 200 days post partum. The CTL response of these offspring showed no significant change from that obtained from their sex- and age-matched control counterparts exposed prenatally to the vehicle. NK responses of chlordane-exposed female offspring were significantly higher at 100 days of age but not at 200 days of age. Although male offspring that were exposed to chlordane prenatally showed no difference in NK cell activity at 100 days of age, NK cell activity was significantly less in chlordane-treated animals than controls at 200 days of age. Thus, prenatal treatment of mice with chlordane had varying effects on the NK cell activity of adult offspring, depending on the sex and age of the animal. It is concluded that the previously reported increase in survival to influenza is due to a resolution of the infection by normal CTL and NK cell activities coupled with a decrease in delayed-type hypersensitivity (DTH)-mediated pathology.

Reproductive toxicity: male and female reproductive systems as targets for chemical injury

On the basis of current knowledge of reproductive biology and toxicology, it is apparent that chemicals affecting reproduction may elicit their effects at a number of sites in both the male and the female reproductive system. This multiplicity of targets is attributable to the dynamic nature of the reproductive system, in which the hypothalamic-pituitary-gonadal axis is controlled by precise positive and negative feedback mechanisms among its components. Interference by a xenobiotic at any level in either the male or the female reproductive system may ultimately impair hypothalamic or pituitary function. Normal gonadal processes such as spermatogenesis or oogenesis, ejaculation or ovulation, hormone production by Leydig or granulosa cells, and the structure or function of the accessory reproductive structures (e.g., epididymis, fallopian tube) also appear vulnerable to xenobiotics. The reproductive system is a complex one that requires local and circulating hormones for control. This brief review illustrates a system for characterizing the mechanism of action of reproductive toxicants, as well as for defining the sites available for disruption of reproduction. Unfortunately, at present, data addressing the actual vulnerability of reproduction are sorely lacking. However, when experiments have been conducted and combined with epidemiologic data or clinical observation, it has been possible to demonstrate impairment of reproductive processes by xenobiotics. The role of environmental exposure to xenobiotics in the increase in infertility that has been observed remains to be defined.

Effects of selected chemicals on the glutathione status in the male reproductive system of rats

Previous studies have suggested a significant role for reproductive tract glutathione in protecting against chemical-induced germ-cell mutations. Therefore, a number of compounds were tested for their ability to perturb glutathione levels in the testes and epididymides as well as liver following single acute dosages to rats. Phorone (250 mg/kg), isophorone (500 mg/kg), and diethyl maleate (500 mg/kg) significantly reduced glutathione in the liver and in both reproductive organs examined. Methyl iodide (100 mg/kg), trimethyl phosphate (600 mg/kg), naphthalene (500 mg/kg), acetaminophen (1500 mg/kg), and pentachlorophenol (25 mg/kg) affected hepatic and epididymal glutathione, but had little or no effect on testicular levels. The ability of isophorone to enhance the covalent binding of tritiated ethyl methanesulfonate (3H-EMS) to spermatocytes was assessed. Perturbation of reproductive tract glutathione by isophorone treatment significantly enhanced the extent of 3H-EMS-induced binding to sperm heads. The temporal pattern of ethylations in sperm heads was consistent with the stage of sperm development known to be susceptible to ethylations by EMS. Therefore, chemical-induced lowering of glutathione in the male reproductive tract may be a mechanism for potentiation of chemical-induced germ-cell mutations.