Interlayer structure and self-healing in suspensions of brush-stabilized nanoplatelets with smectic order.

We have investigated the rheology of an uncured epoxy fluid containing high aspect ratio (length/thickness ≈ 160) α-zirconium phosphate (ZrP) nanoplatelets with smectic order. The nanoplatelets were exfoliated into monocrystalline sheets with uniform thickness using a monoamine-terminated oligomer. The oligomers were densely grafted to the plate surfaces and behave as a molecular brush. Suspensions containing ∼ 2 vol.% ZrP and above show liquid crystalline order with scattering peaks characteristic of a smectic (layered) mesophase. At much higher loading, ∼ 4 vol.% ZrP, there is a sharp transition in visual appearance, steady shear rheology, and linear and non-linear viscoelasticity that is attributed to the reversible interdigitation of oligomer chains between closely spaced layers. The oligomers are proposed to serve as inter-lamellar bridges that store elastic stresses for intermediate rates of deformation, but are able to relax on longer time scales. Under steady shearing conditions, the smectic suspensions with "overlapped" microstructure show a discontinuous flow curve characteristic of shear banding that is attributed to the dynamic pull-out of oligomer chains from the overlap region. At high shear rates, the limiting viscosity of the concentrated suspensions is on the same order of magnitude as the unfilled suspending fluid. When the rate of deformation is reduced below a critical time scale, the original network strength, and corresponding microstructure, is recovered through a passive self-healing process. The unique combination of concentration-dependent yield stress, low post-yield viscosity, and self-healing is potentially useful for various applications in the liquid state, and desirable for scalable processing of nanocomposite materials for structural applications.

Does nausea and vomiting of pregnancy play a role in the association found between maternal caffeine intake and fetal growth restriction?

The aim of this study was to explore the relationships between nausea and vomiting in pregnancy and (a) fetal growth restriction; and (b) maternal caffeine metabolism and fetal growth restriction. A cohort of 2,643 pregnant women, aged 18-45 years, attending two UK maternity units between 8 and 12 weeks gestation, was recruited. A validated tool assessed caffeine intake at different stages of pregnancy and caffeine metabolism was assessed from a caffeine challenge test. Experience of nausea and vomiting of pregnancy was self-reported for each trimester. Adjustment was made for confounders, including salivary cotinine as a biomarker of current smoking status. There were no significant associations between fetal growth restriction and nausea and vomiting in pregnancy, even after adjustment for smoking and alcohol intake. There were no significant differences in the relationship between caffeine intake and fetal growth restriction between those experiencing symptoms of nausea and vomiting and those who did not, for either the first (p = 0.50) or second trimester (p = 0.61) after adjustment for smoking, alcohol intake and caffeine half-life. There were also no significant differences in the relationship between caffeine half-life and fetal growth restriction between those experiencing symptoms of nausea and vomiting and those who did not, for either the first trimester (p = 0.91) or the second trimester (p = 0.45) after adjusting for smoking, alcohol intake and caffeine intake. The results from this study show no evidence that the relationship between maternal caffeine intake and fetal growth restriction is modified by nausea and vomiting in pregnancy.

Airway obstruction related to diacetyl exposure at microwave popcorn production facilities.

Obstructive lung diseases including bronchiolitis obliterans have been reported among microwave popcorn production employees. Butter flavourings including diacetyl have been associated with these findings. The present study was initiated at four microwave popcorn production plants to determine if exposure to diacetyl was associated with decrements in pulmonary function. Comprehensive diacetyl exposure assessment was undertaken for all job tasks. Spirometry was conducted for 765 full-time employees between 2005 and 2006. Outcomes included decrement in forced expiratory volume in one second (FEV(1)) % predicted, airway obstruction and persistent decline in FEV(1). Inclusion in the high-exposure group (mixers) prior to respirator use was associated with a significantly decreased FEV(1) % pred in non-Asian and Asian males at -6.1 and -11.8% pred, respectively, and an eight-fold increased risk for airway obstruction. Cumulative diacetyl exposure >or=0.8 ppm-yr caused similar results. No significant impact was seen in nonmixers or between current diacetyl exposure and persistent decline in FEV(1). Unprotected exposure as a mixer to butter flavouring including diacetyl resulted in decrements in FEV(1) (% pred) and increased airway obstruction. Control of employee exposure to butter flavouring additives is warranted in regard to both short-term peak and 8-h workday exposure.

Global gene expression analysis of bovine somatic cell nuclear transfer blastocysts and cotyledons.

Low developmental competence of bovine somatic cell nuclear transfer (SCNT) embryos is a universal problem. Abnormal placentation has been commonly reported in SCNT pregnancies from a number of species. The present study employed Affymetrix bovine expression microarrays to examine global gene expression patterns of SCNT and in vivo produced (AI) blastocysts as well as cotyledons from day-70 SCNT and AI pregnancies. SCNT and AI embryos and cotyledons were analyzed for differential expression. Also in an attempt to establish a link between abnormal gene expression patterns in early embryos and cotyledons, differentially expressed genes were compared between the two studies. Microarray analysis yielded a list of 28 genes differentially expressed between SCNT and AI blastocysts and 19 differentially expressed cotyledon genes. None of the differentially expressed genes were common to both groups, although major histocompatibility complex I (MHCI) was significant in the embryo data and approached significance in the cotyledon data. This is the first study to report global gene expression patterns in bovine AI and SCNT cotyledons. The embryonic gene expression data reported here adds to a growing body of data that indicates the common occurrence of aberrant gene expression in early SCNT embryos.

Chesterton soil concretions: ilmenite and not iron-manganese cementing matrix.

Dark reddish-brown spherules are common in soils of the Chesterton soil series of a high marine terrace in southern California. The spherules are concretionary in structure and are bound by ilmenite rather than by an iron-manganese complex. The spherules have been mislabeled both with respect to structure and mineralogy.

Does the Use of Volumetric Modulated Arc Therapy Reduce Gastrointestinal Symptoms after Pelvic Radiotherapy?

AIMS: Growing numbers of patients with cancer are surviving after treatment with pelvic radiotherapy. We evaluated the technique of volumetric modulated arc therapy (VMAT), which delivers a decreased dose to the organs at risk. We aimed to determine outcomes of this technique in terms of patient-reported acute toxicity and late effects and correlate the frequency of gastrointestinal symptoms with the volume of bowel receiving radiation dose. MATERIALS AND METHODS: Patients who were to receive VMAT for gynaecological malignancy completed patient-reported outcomes at baseline, the end of treatment, 8 weeks and 1 year. The rates of patient-reported toxicity were correlated with the volume of bowel irradiated. RESULTS: The frequencies of patient-reported gastrointestinal symptoms increased in the acute toxicity phase and tended to improve at 1 year, with the exception of faecal incontinence and rectal bleeding (P < 0.05). There was not a strong association between the volume of small bowel that was irradiated (P > 0.05 at all dose levels) and reported toxicity, suggesting that other factors are involved in the development of toxicity. CONCLUSION: Although VMAT decreases the dose delivered to the small bowel, this does not translate into a reduction in patient-reported toxicity.

Modulation of immune response following dietary genistein exposure in F0 and F1 generations of C57BL/6 mice: evidence of thymic regulation.

To further determine whether genistein (GEN) modulation of the immune responses was related to its endocrine-disrupting properties and time of exposure, pregnant C57BL/6 mice were exposed to GEN at 0-1250 ppm in feed starting on day 14 of gestation. The C57BL/6 offspring were exposed to GEN in utero and lactationally, and through feed after weaning until postnatal day 42. In dams, exposure to GEN increased the terminal body weight (250 and 1250 ppm), the number of splenic T cells and NK cells (250 ppm), and the activity of NK cells (250 ppm). In F(1) males, GEN increased the terminal body and spleen weights (25 and 250 ppm), the number of CD4(+)CD8(+) and CD4(-)CD8(+) thymocytes (25 ppm), and the number of splenic T cell subsets and NK cells (25 and 250 ppm). Moreover, splenic NK cell activity and anti-CD3-mediated splenocyte proliferation were increased in all treatment groups. In F(1) females, the percentages of CD4(-)CD8(+) and CD4(-)CD8(-) thymocytes (25 and 250 ppm), and CD4(+)CD8(-) and CD4(+)CD8(+) splenocytes (25 and 250 ppm) were increased. In contrast, the percentage and number of CD4(+)CD8(+) thymocytes were decreased (250 ppm). Exposure to GEN decreased the percentages of splenic NK cells in all treatment groups, and decreased the activity of splenic NK cells at the 25 ppm concentration. Additionally, evaluation of CD25(+) and CD44(+) expression by thymocytes indicated that the decrease in the percentage of CD44(+)CD25(+) thymocytes was at least partially responsible for the decrease in the percentage of CD4(-)CD8(-) thymocytes in F(1) male mice. Overall, the results demonstrate that GEN can modulate the immune system in both adult and developing C57BL/6 mice in a dose-specific manner. The gender-specific effects of GEN on the immune responses in F(1) mice suggest that GEN may modulate the immune system by functioning as either an estrogen agonist or antagonist. The differential effects of GEN on thymocytes in F(1) male and female mice indicate that GEN immunomodulation might be related to its effect on thymus.

Suppression of the vitro humoral immune response of mouse splenocytes by benzo(a)pyrene metabolites and inhibition of benzo(a)pyrene-induced immunosuppression by alpha-naphthoflavone.

Several investigators have demonstrated that the humoral immune response of mice and splenocyte cultures was suppressed with benzo(a)pyrene [B(a)P] exposure. The mechanism of the B(a)P immunosuppression, however, has not been established. Since reactive metabolites of B(a)P, rather than the parent compound, have been shown to mediate the carcinogenic effects of B(a)P, it was hypothesized that the immunosuppression produced by B(a)P may also be mediated by its reactive metabolites. The objective of this investigation was to examine the role of B(a)P metabolism in the B(a)P-induced suppression of the in vitro humoral immune response. This was addressed by first determining if various B(a)P metabolites are capable of inhibiting the generation of antibody-forming cells (AFC) of splenocyte cultures. Addition of B(a)P or B(a)P-7,8-diol (2 X 10(-5) M) to splenocyte cultures produced a similar dose-dependent suppression of the in vitro T-dependent AFC response to sheep red blood cells. In contrast, decreases in the AFC response and cell viability of cultures exposed to the 4,5-diol or 9,10-diol were only observed at 2 X 10(-5) M. Exposure of cultures to 3-hydroxy-B(a)P resulted in a significant decrease in the AFC response at 2 X 10(-6) and 2 X 10(-5) M. Slight decreases in the AFC response were observed with the addition of B(a)P-4,5-epoxide or B(a)P-6,12-dione at 2 X 10(-6) M, whereas a dramatic decrease in the AFC response, as well as a 45% decrease in cell viability, was obtained at 2 X 10(-5) M. The second objective was to examine the effects of the cytochrome P-450 inhibitor, alpha-naphthoflavone (ANF), on the B(a)P- and B(a)P-7,8-diol-induced suppression of the in vitro AFC response. Exposure of splenocyte cultures to 2 X 10(-5) M ANF did not affect the AFC response. Coincubation of splenocytes with ANF was observed to attenuate the suppressive effects of B(a)P and B(a)P-7,8-diol. This concentration of ANF was observed to inhibit the metabolism of [3H]B(a)P by splenocyte cultures to water soluble metabolites. Moreover, B(a)P metabolism by splenic microsomal preparations of untreated mice was inhibited by ANF. These findings suggest that the B(a)P-induced suppression of the in vitro AFC response is mediated by B(a)P metabolites generated by cytochrome P-450 present within splenocytes.

Enhancement of in vivo and in vitro murine immune responses by the cyclophosphamide metabolite acrolein.

Cyclophosphamide (CY)-mediated immunoenhancement has been attributed to the inhibition of suppressor T-cell generation. In order to exert its effects on the immune system, metabolic activation of CY is required. The metabolite of CY responsible for its immunoenhancing properties are not known. Two reactive metabolites of CY which may inhibit suppressor T-cell generation are phosphoramide mustard and acrolein, compounds known to primarily bind to DNA and sulfhydryl groups, respectively. The objective of this study was to determine whether acrolein and/or phosphoramide mustard are capable of enhancing the immune response in a manner similar to CY. Administration of 100 mumol/kg of acrolein, i.v., to female C57BL/6 x C3H F1 mice 1 day before antigen exposure (sheep red blood cells) resulted in a 50% increase in the delayed-type hypersensitivity response (foot pad swelling). The Day 4 primary humoral immune response to sheep red blood cells was also increased by 88 and 60% after the administration of 30 and 100 mumol/kg acrolein 1 day before sensitization with sheep red blood cells. Exposure of splenocyte cultures to 3 x 10(-7) and 10(-6) M 4-hydroperoxy-CY or acrolein produced significant increases in the in vitro T-dependent antibody-forming cell response. In contrast, the antibody-forming cell response of cultures exposed to 3 x 10(-8) - 10(-4) M phosphoramide mustard did not increase above control levels. These results suggest that acrolein is responsible for the CY-induced enhancement of the immune response. Moreover, the enhancement may be produced by the binding of acrolein to sulfhydryl groups of molecules of cells required for the generation of suppressor T-cells.

Benzo(a)pyrene metabolism by murine spleen microsomes.

The immunosuppressive actions of benzo(a)pyrene have been proposed to be mediated by reactive metabolites rather than the parent compound. Reactive metabolites which suppress splenic humoral immune responses are thought to be generated within the spleen rather than in distant tissues. Although the spleen has been shown to be capable of metabolizing benzo(a)pyrene, the relative amounts and types of metabolites generated have not been determined. In this study, high-pressure liquid chromatography was used to separate benzo(a)pyrene metabolites generated by splenic microsomes. The major metabolites generated by the splenic microsomal preparations of untreated female B6C3F1 mice were found to be the 9,10- and 7,8-dihydrodiols and 9-, 7-, and 3-hydroxy benzo(a)pyrene. The 1,3-, 3,6-, and 6,12-diones and 4,5-dihydrodiol constituted only a small fraction of the metabolites generated. The generation of all metabolites were inhibited by alpha-naphthoflavone and antiserum to NADPH-cytochrome P-450 reductase, whereas SKF 525-A had only a minimal effect. Dihydrodiol production was completely inhibited by the epoxide hydrolase inhibitor, trichloropropylene oxide. Benzo(a)pyrene pretreatment of mice produced a dramatic increase in the amount of metabolites formed; however, the pattern of metabolites remained similar to that generated by splenic microsomes of untreated mice. The role of prostaglandin synthetase in generating these metabolites was also examined. The addition of arachidonic acid in place of NADPH resulted in the formation of only quinones. Dihydrodiols and phenols were undetectable. The results of this study indicate that splenocytes may be capable of generating the 7,8-dihydrodiol, the precursor to the highly reactive 7,8-dihydrodiol-9,10-epoxide. Furthermore, the addition of the 7,8-dihydrodiol-9,10-epoxide to splenocyte cultures resulted in a decreased in vitro antibody forming cell response to sheep red blood cells. Thus, benzo(a)pyrene-induced immunosuppression may be mediated by the dihydrodiol-epoxide generated within the spleen. Since benzo(a)pyrene exposure was found to increase its own metabolism, immunosuppression produced by the administration of benzo(a)pyrene over several days may be the result of an increased production of immunosuppressive metabolites. The pattern of metabolites generated and the effects of the two types of cytochrome P-450 inhibitors suggests that the major isozyme of cytochrome P-450 that mediates the metabolism of benzo(a)pyrene within the spleen of untreated mice may be similar to the isozyme induced in the liver upon pretreatment with polycyclic aromatic hydrocarbons.

Direct suppression of in vitro antibody production by mouse spleen cells by the carcinogen benzo(a)pyrene but not by the noncarcinogenic congener benzo(e)pyrene.

The role of metabolic activation of benzo(a)pyrene B(a)P in mediating its suppression of humoral immune responsiveness of the female C57BL/6 X C3H F1 (hereafter called B6C3F1) mouse was addressed in these studies. The model was the in vitro antibody response by untreated splenic suspensions, to which was added directly either B(a)P or benzo(e)pyrene B(e)P. B(a)P suppressed the antibody response to DNP-Ficoll and sheep erythrocytes but not the polyclonal antibody response to LPS. This activity neither required nor was affected by addition of a metabolic activation system (i.e., S-9 crude liver homogenate from Aroclor-induced B6C3F1 mice) at 3 times the concentration (based on determination of protein content) which readily activated cyclophosphamide. Preliminary results with radiolabeled B(a)P verified that appreciable amounts of hydroxylated metabolites of B(a)P were obtained after only a 30-min preincubation. Therefore, production of the reactive metabolites of B(a)P which mediate its carcinogenicity are not essential for its immunosuppressive activity. The results, showing a parallel in the immunosuppressive profile of activity of B(a)P and the lack of immunosuppressive activity of B(e)P following in vivo and in vitro exposure, indicate that the in vitro antibody systems offer an ideal model system to characterize the PAHs.

Effective cryopreservation of golden Syrian hamster embryos by open pulled straw vitrification.

Golden Syrian hamster embryos are difficult to cryopreserve due to their high sensitivity to cryoprotectants and in vitro handling. The objective of this study is to develop a robust open pulled straw (OPS) vitrification technique for cryopreserving hamster embryos at various developmental stages. We first systematically tested the concentrations of cryoprotectants and the exposure times of two-cell embryos to various vitrification solutions. We identified pretreatment of two-cell embryos with 10% (v/v) ethylene glycol (EG) + 10% (v/v) dimethylsulfoxide (DMSO) for 30 s followed by exposure in the vitrification solution, EDFS30 (containing 15% EG + 15% DMSO), for 30 s before plunging into liquid nitrogen (two-step exposure method) as the optimal OPS vitrification protocol. We then investigated the resourcefulness of this protocol for vitrifying hamster embryos at different developmental stages. The results showed that high blastocyst rates from embryos vitrified at two-cell, four-cell, eight-cell, or morula stage (62%, 78%, 80%, or 72%, respectively), but not those verified at pronuclear (0%) or blastocyst stage (24%; P < 0.05), were achieved by this protocol. When embryos vitrified at the two-cell stage were recovered and then directly transferred to recipient females, 29% of them developed to term, a development rate not significantly different (P > 0.05) from the 40% birth rate of the unvitrified controls. In conclusion, we have developed an effective two-step OPS vitrification protocol for hamster embryos.

A multicentre, prospective, randomised, blinded clinical trial to compare some perioperative effects of buprenorphine or butorphanol premedication before equine elective general anaesthesia and surgery.

REASONS FOR PERFORMING STUDY: Buprenorphine, a µ-agonist opioid, has recently been licensed for equine use, but butorphanol, a κ-agonist opioid, is more commonly used in horses. The effect of the 2 opioids has not previously been compared in a large clinical study. OBJECTIVES: To compare post operative analgesia and physiological variables in horses undergoing elective surgery following premedication with either buprenorphine or butorphanol in a conventional clinical setting. STUDY DESIGN: Multicentre, prospective, randomised, blinded clinical investigation. METHODS: Eighty-nine healthy horses admitted for elective surgery to one of 6 UK equine veterinary clinics were premedicated with acepromazine, a nonsteroidal anti-inflammatory drug, and romifidine followed by intravenous (i.v.) buprenorphine or butorphanol. Anaesthesia was induced with diazepam/ketamine and maintained with isoflurane in oxygen. A range of surgical procedures were performed and supplementary anaesthetic agents given as required. Physiological variables were monitored during anaesthesia and pain, ataxia, sedation and vital function were assessed post operatively. Data were analysed using t-tests, ANOVA, Mann-Whitney U-test and Chi-squared test as appropriate and P<0.05 was regarded as significant, except for multiple comparisons, when P<0.01 was used. RESULTS: Surgery was carried out successfully in all cases and no mortality or serious morbidity occurred. Physiological variables remained within normal limits and all horses recovered successfully, most standing within 1 h of ceasing anaesthesia. There were no significant differences between groups in any variable except post operative pain when scores (simple descriptive scale) between 3 and 6 h were significantly lower after buprenorphine than after butorphanol. CONCLUSIONS: Horses experienced less post operative pain after buprenorphine than after butorphanol premedication. Compared with butorphanol, buprenorphine did not cause any different effects on vital function.

Phenotypic relationships between docility and reproduction in Angus heifers.

The objective of this study was to elucidate the phenotypic relationships between docility and first-service AI conception rate in heifers. Data ( = 337) collected from 3 cooperator herds in Kansas at the start of synchronization protocol included exit velocity (EV), chute score (CS), fecal cortisol (FC), and blood serum cortisol (BC). Data were analyzed using logistic regression with 30-d pregnancy rate as the dependent variable. The model included the fixed effect of contemporary group and the covariates FC, BC, EV, CS, BW, and age. Correlation coefficients were calculated between all continuous traits. Pregnancy rate ranged from 34% to 60% between herds. Blood cortisol positively correlated with EV ( = 0.22, < 0.01), negatively correlated with age ( = -0.12, < 0.03), and tended to be negatively correlated with BW ( = -0.10, = 0.09). Exit velocity was positively correlated with CS ( = 0.24, < 0.01) and negatively correlated with BW ( = -0.15, < 0.01) and age ( = -0.12, < 0.03). Chute score negatively correlated with age ( = -0.14, < 0.01), and age and BW were moderately positively correlated ( = 0.42, < 0.01), as expected. Older, heavier animals generally had better temperament, as indicated by lower BC, EV, and CS. The power of our test could detect no significant predictors of 30-d pregnancy for the combined data from all ranches. When the data were divided by ranch, CS ( < 0.03) and BW ( < 0.01) were both significant predictors for 30-d pregnancy for ranch 1. The odds ratio estimate for CS has an inverse relationship with pregnancy, meaning that a 1-unit increase in average CS will reduce the probability of pregnancy at ranch 1 by 48.1%. Weight also has a negative impact on pregnancy because a 1-kg increase in BW will decrease the probability of pregnancy by 2.2%. Fertility is a complex trait that depends on many factors; our data suggest that docility is 1 factor that warrants further investigation.

The adjuvancy of silicones: dependency on compartmentalization.

Studies have been conducted in mice (B6C3F1) and rats (Sprague Dawley, Fischer 344) to investigate the adjuvancy potential of silicone mammary gel and the low molecular weight silicone fluid, octamethylcyclotetrasiloxane (D4). Dependent on the experimental conditions employed, a divergent data profile emerges. If the antigen (bovine serum albumin, BSA) is emulsified with either the gel or the D4 prior to intramuscular immunization, an amplified anti-BSA IgG antibody response, as measured by multipoint ELISA methodology, is noted over the 8 week measurement period. In parallel studies, a variety of non-silicone personal care ingredients (lanolin, white mineral oil, isopropyl palmitate) were also capable of amplifying this humoral response relative to the non-adjuvant phosphate buffered saline control. These observations are consistent with the empirical knowledge that hydrophobic substances tend to augment immune responses. However, under conditions in which the antigen is not blended with the silicone prior to immunization, normal immune responses are noted. In short (10 day) and long (180 day) term gel implant studies, the optimal IgM and IgG antibody responses, as determined in the antibody forming cell assay, were equivalent between the gel implanted and control animals. Moreover, under similar exposure conditions, no adjuvancy was noted in the three Host Resistance models (B16F10 Melanoma, Listeria monocytogenes, and Streptococcus pneumoniae) tested. Antibody forming cell studies conducted after 28 days of oral or inhalation exposure to D4 have also yielded responses similar to the non-silicone exposed vehicle controls. Collectively, these data suggest that in the absence of premixing the antigen with the silicone test material, there does not appear to be any silicone induced adjuvant response.

The safety and efficacy of combined amitriptyline and tranylcypromine antidepressant treatment. A controlled trial.

Sixty patients meeting DSM-III criteria for major depression were assigned randomly to double-blind treatment for four weeks according to fixed-dosage steps with (1) amitriptyline hydrochloride alone, up to a maximum dosage of 300 mg/day; (2) tranylcypromine alone, up to 40 mg/day; or (3) the combination of amitriptyline hydrochloride, up to 150 mg/day, and tranylcypromine, up to 20 mg/day. The conditions of patients in all three treatment groups improved equally. The combined treatment did not produce a higher frequency of side effects, and no side effects, such as hypertensive or hyperthermic crises, occurred in any patient. Both amitriptyline alone and combined treatment produced substantially more anticholinergic side effects than did tranylcypromine. These results support the safety and efficacy of the combined treatment, although claims for superior efficacy over single-antidepressant treatments in this heterogenous population were not supported.

Oral exposure to atrazine modulates cell-mediated immune function and decreases host resistance to the B16F10 tumor model in female B6C3F1 mice.

Atrazine (ATZ) is used throughout North America to control annual broadleaf weeds and grasses in various crops including; corn, sorghum, and sugar cane. Unfortunately, contamination of surface and ground water has occurred as a result of ATZ's chemical and physical properties, and its widespread use throughout the U.S. Midwest. A study of ATZ's immunomodulatory properties was conducted using female B6C3F1 mice and a panel of immune assays and host resistance models designed to evaluate cell-mediated and antibody-mediated immunity. Mice were administered ATZ by gavage (0, 24, 250, and 500 mg/kg/day) for 14 days then evaluated for immune responsiveness. ATZ treatment significantly increased the number of splenic CD8+ T cells, cytotoxic T cell and mixed leukocyte responses, and dose-dependently reduced host resistance to B16F10 melanoma. Thymus and spleen weights, total spleen cell numbers and fixed macrophage function was also reduced in mice that were exposed to ATZ. These results demonstrate that oral ATZ exposure is sufficient to alter cell-mediated immune function and disease resistance in female B6C3F1 mice.

Myelotoxicity in genistein-, nonylphenol-, methoxychlor-, vinclozolin- or ethinyl estradiol-exposed F1 generations of Sprague-Dawley rats following developmental and adult exposures.

The myelotoxicity of five endocrine active chemicals was evaluated in F1 generation of Sprague-Dawley rats following developmental and adult exposures at three concentration levels. Rats were exposed to genistein (GEN: 25, 250 and 1250 ppm), nonylphenol (NPH: 25, 500 and 2000 ppm), methoxychlor (MXC: 10, 100 and 1000 ppm), vinclozolin (VCZ: 10, 150 and 750 ppm) and ethinyl estradiol (EE2: 5, 25 and 200 ppb) gestationally and lactationally through dams from day 7 of gestation and through feed after weaning on postnatal day (PND) 22 to PND 64. The parameters examined included the number of recovered bone marrow cells, DNA synthesis, and colony forming units (CFU) in the presence of granulocyte macrophage-colony stimulating factor (GM-CSF), macrophage colony-stimulating factor (M-CSF) and erythropoietin. Except for the EE2, the concentrations of other individual chemicals in the diet were in an approximate range that allowed for a comparison to be made in terms of myelotoxic potency. Decreases in the DNA synthesis, CFU-GM and CFU-M seemed to be the common findings among the alterations induced by these compounds. Using the numbers of alterations induced by each chemical in the parameters examined as criteria for comparison, the order of myelotoxic potency in F(1) males was: GEN>MXC>NPH>VCZ; the order in females: GEN>NPH>VCZ. Additionally, some of the functional changes induced by these compounds were gender-specific or dimorphic. Overall, the results demonstrated that developmental and adult exposures of F1 rats to these endocrine active chemicals at the concentrations tested had varied degrees of myelotoxicity with GEN being the most potent. Furthermore, the sex-specific effects of these chemicals in F1 male and female rats suggest that there may be interactions between these compounds and sex hormone in modulating these responses.

Dietary methoxychlor exposure modulates splenic natural killer cell activity, antibody-forming cell response and phenotypic marker expression in F0 and F1 generations of Sprague Dawley rats.

Methoxychlor, a chlorinated hydrocarbon pesticide, is a persistent environmental contaminant that has been identified in human reproductive tissues. Methoxychlor has been shown to be estrogenic in both in vivo and in vitro studies. As an endocrine disrupter, it may have the potential to adversely affect endocrine, reproductive, and immune systems in animals. The present study evaluated methoxychlor's immunotoxic potential in F0 (dams) and F1 generations of Sprague Dawley rats exposed to an isoflavone-free diet containing methoxychlor at concentrations of 10, 100, and 1000 ppm. In dams, exposure to methoxychlor from gestation day 7 to postpartum day 51 (65 days total exposure) produced a significant increase in the NK activity (1000 ppm) and the percentages of T cells (1000 ppm), helper T cells (1000 ppm) and macrophages (100 and 1000 ppm). In contrast, a decrease in the numbers of splenocytes and B cells was observed at the 100 and 1000 ppm concentrations. In F1 males, exposure to methoxychlor gestationally, lactationally and through feed from postnatal day 22-64 (78 days total exposure) produced an increase in the spleen IgM antibody-forming cell response to sheep red blood cells (100 and 1000 ppm) and the activity of NK cells (1000 ppm). However, there was a decrease in the terminal body weight (1000 ppm), spleen weight (1000 ppm), thymus weight (100 and 1000 ppm), and the numbers of splenocytes (1000 ppm), B cells (100 and 1000 ppm), cytotoxic T cells (1000 ppm) and NK cells (100 and 1000 ppm). In F1 females, exposure to methoxychlor produced a decrease in the terminal body weight (1000 ppm) and the percentages of cytotoxic T cells (10, 100 and 1000 ppm). These results demonstrate that developmental and adult dietary exposure to methoxychlor modulates immune responses in Sprague Dawley rats. Immunological changes were more pronounced in the F1 generation male rats that were exposed during gestation and postpartum, when compared to the F0 and F1 generation females. Increases in antibody-forming cell response and NK cell activity, and altered spleen cell subpopulation numbers were observed in the F1 generation male rats, without similar changes to the F1 generation females.

Benzo(a)pyrene-induced anemia and splenomegaly in NZB/WF1 mice.

Benzo(a)pyrene (BaP), a polycyclic aromatic hydrocarbon, is a known immunomodulator. At high doses, BaP is immunosuppressive but at low doses it can enhance the immune response. Studies were conducted to determine if BaP would exacerbate the development of autoimmune disease in genetically prone NZB/WF1 mice. Five week old female NZBW/F1 mice were exposed dermally to 5, 20 and 40 mg/kg BaP for 30 days. Vehicle mice were exposed to an acetone:olive oil mixture for 30 days. BaP did not increase total IgG, anti-DNP-HSA or anti-dsDNA antibody levels. However, hematological evaluation revealed a decrease in erythrocyte number, hemoglobin and hematocrit and an increase in mean corpuscular volume and red cell distribution width in the 20 and 40 mg/kg dose groups. Liver and spleen weights were increased in the high dose groups; however, an increase in spleen cell number was not observed. Histopathological evaluation revealed splenic red pulp expansion in a mouse treated with 40 mg/kg BaP. An increase in splenic CFU-e production was observed in mice treated with 20 and 40 mg/kg BaP. A decrease in splenic total B cells, total T cells, CD4(+) and CD8(+) T cells was observed in mice treated with 20 and 40 mg/kg BaP. An increase in splenic null cells (non-T, non-B cells) was also observed in the high dose groups, consistent with extramedullary hematopoiesis. Coombs' tests, flow cytometry and an immune-mediated hemolysis assay indicated that the anemia was not autoimmune-mediated. Although no change was observed in the percentage of reticulocytes in these animals, further bone marrow analysis is needed to determine if the anemia is due to bone marrow suppression, possibly caused by BaP exposure, or chemical-induced hemolysis, perhaps contributed to by erythrocyte fragility inherited from a parent strain, NZB, which spontaneously develops autoimmune hemolytic anemia and subsequent splenomegaly.