Maternal obesity modulates sexually dimorphic epigenetic regulation and expression of leptin receptor in offspring hippocampus.

Maternal obesity during pregnancy is associated with a greater risk for obesity and neurodevelopmental deficits in offspring. This developmental programming of disease is proposed to involve neuroendocrine, inflammatory, and epigenetic factors during gestation that disrupt normal fetal brain development. The hormones leptin and insulin are each intrinsically linked to metabolism, inflammation, and neurodevelopment, which led us to hypothesise that maternal obesity may disrupt leptin or insulin receptor signalling in the developing brain of offspring. Using a C57BL/6 mouse model of high fat diet-induced maternal obesity (mHFD), we performed qPCR to examine leptin receptor (Lepr) and insulin receptor (Insr) gene expression in gestational day (GD) 17.5 fetal brain. We found a significant effect of maternal diet and offspring sex on Lepr regulation in the developing hippocampus, with increased Lepr expression in female mHFD offspring (p < 0.05) compared to controls. Maternal diet did not alter hippocampal Insr in the fetal brain, or Lepr or Insr in prefrontal cortex, amygdala, or hypothalamus of female or male offspring. Chromatin immunoprecipitation revealed decreased binding of histones possessing the repressive histone mark H3K9me3 at the Lepr promoter (p < 0.05) in hippocampus of female mHFD offspring compared to controls, but not in males. Sex-specific deregulation of Lepr could be reproduced in vitro by exposing female hippocampal neurons to the obesity related proinflammatory cytokine IL-6, but not IL-17a or IFNG. Our findings indicate that the obesity-related proinflammatory cytokine IL-6 during pregnancy leads to sexually dimorphic changes in the modifications of histones binding at the Lepr gene promoter, and concomitant changes to Lepr transcription in the developing hippocampus. This suggests that exposure of the fetus to metabolic inflammatory molecules can impact epigenetic regulation of gene expression in the developing hippocampus.

von Frey anesthesiometry to assess sensory impairment after acute spinal cord injury caused by thoracolumbar intervertebral disc extrusion in dogs.

Sensory threshold (ST) was measured using an electric von Frey anesthesiometer (VFA) in all limbs of 20 normal dogs and 29 dogs with acute thoracolumbar spinal cord injury (SCI) caused by spontaneous intervertebral disc extrusion. ST values were measured at three separate time points in normal dogs and on days 3, 10 and 30 following decompressive surgery in dogs with SCI. ST values were compared between groups and correlated with locomotor recovery in SCI-affected dogs. ST values were significantly higher (consistent with hypoalgesia) in the pelvic limbs of SCI-affected dogs at day 3, day 10 and day 30 when compared to normal dogs (P <0.05), while no significant difference in thoracic limb ST values was observed between groups. A progressive decrease in pelvic limb ST values occurred in SCI-affected dogs over time, consistent with improvement toward normal sensation or development of allodynia. This finding correlated inversely with locomotor score at 3 and 10 days after surgery. A significant decline in ST values across testing sessions was observed for all limbs of normal and SCI-affected dogs and may be related to patient acclimation, operator training effect, or effect of analgesic medications. This study supports the feasibility of VFA to assess differences in ST between normal and SCI-affected dogs. However, future studies must focus on techniques to minimize or compensate for clinical, environmental and behavioral factors which may impact ST values in the clinical setting.

A simplified method of walking track analysis to assess short-term locomotor recovery after acute spinal cord injury caused by thoracolumbar intervertebral disc extrusion in dogs.

The purpose of this study was to evaluate a simplified method of walking track analysis to assess treatment outcome in canine spinal cord injury. Measurements of stride length (SL) and base of support (BS) were made using a 'finger painting' technique for footprint analysis in all limbs of 20 normal dogs and 27 dogs with 28 episodes of acute thoracolumbar spinal cord injury (SCI) caused by spontaneous intervertebral disc extrusion. Measurements were determined at three separate time points in normal dogs and on days 3, 10 and 30 following decompressive surgery in dogs with SCI. Values for SL, BS and coefficient of variance (COV) for each parameter were compared between groups at each time point. Mean SL was significantly shorter in all four limbs of SCI-affected dogs at days 3, 10, and 30 compared to normal dogs. SL gradually increased toward normal in the 30 days following surgery. As measured by this technique, the COV-SL was significantly higher in SCI-affected dogs than normal dogs in both thoracic limbs (TL) and pelvic limbs (PL) only at day 3 after surgery. BS-TL was significantly wider in SCI-affected dogs at days 3, 10 and 30 following surgery compared to normal dogs. These findings support the use of footprint parameters to compare locomotor differences between normal and SCI-affected dogs, and to assess recovery from SCI. Additionally, our results underscore important changes in TL locomotion in thoracolumbar SCI-affected dogs.

Oral (drinking water) two-generation reproductive toxicity study of dibromoacetic acid (DBA) in rats.

In a two-generation study of dibromoacetic acid (DBA), Crl SD rats (30 rats/sex/group/generation) were provided DBA in drinking water at 0 (reverse osmosis-deionized water), 50, 250, and 650 ppm (0, 4.4 to 11.6, 22.4 to 55.6, and 52.4 to 132.0 mg/kg/day, respectively; human intake approximates 0.1 microg/kg/day [0.0001 mg/kg/day]). Observations included viability, clinical signs, water and feed consumption, body and organ weights, histopathology, and reproductive parameters (mating, fertility, abortions, premature deliveries, durations of gestation, litter sizes, sex ratios and viabilities, maternal behaviors, reproductive organ weights, sperm parameters and implantation sites, sexual maturation). Histopathological evaluations were performed on at least 10 P and F1 rats/sex at 0 and 650 ppm (gross lesions, testes, intact epididymis; 10 F1 dams at 0, 250, and 650 ppm for primordial follicles). Developmental observations included implantations, pup numbers, sexes, viabilities, body weights, morphology, and reproductive performance. At 50 ppm and higher, both sexes and generations had increased absolute and relative liver and kidneys weights, and female rats in both generations had reduced absolute and relative adrenal weights; adrenal changes were probably associated with physiological changes in water balance. The livers and kidneys (10/sex/group/generation) had no histopathological changes. Other minimal effects at 50 ppm were reduced water consumption and a transient reduction in body weight. At 250 and 650 ppm, DBA reduced parental water consumption, body weight gains, body weights, feed consumption, and pup body weights. P and F1 generation male rats at 250 and 650 ppm had altered sperm production (retained step 19 spermatids in stages IX and X tubules sometimes associated with residual bodies) and some epididymal tubule changes (increased amounts of exfoliated spermatogenic cells/residual bodies in epididymal tubules, atrophy, and hypospermia), although inconsistently and at much lower incidences. Unilateral abnormalities of the epididymis (small or absent epididymis) at 650 ppm in four F1 generation male rats were considered reproductive tract malformations. The no-observable-adverse-effect level (NOAEL) and reproductive and developmental NOAELs for DBA were at least 50 ppm (4.5 to 11.6 mg/kg/day), 45,000 to 116,000 times the human adult exposure level. Reproductive and developmental effects did not occur in female rats exposed to DBA concentrations as high as 650 ppm. Based on the high multiples of human exposure required to produce effects in male rats, DBA should not be identified as a human reproductive or developmental risk.

Oral (drinking water) two-generation reproductive toxicity study of bromodichloromethane (BDCM) in rats.

Bromodichloromethane (BDCM) was tested for reproductive toxicity in a two-generation study in CRL SD rats. Thirty rats/sex/ group/generation were continuously provided BDCM in drinking water at 0 (control carrier, reverse osmosis membrane-processed water), 50,150, and 450 ppm (0, 4.1 to 12.6, 11.6 to 40.2, and 29.5 to 109.0 mg/kg/day, respectively). Adult human intake approximates 0.8 microg/kg/day (0.0008 mg/kg/day). P and F1 rats were observed for general toxicity (viability, clinical signs, water and feed consumption, body weights, organ weights [also three weanling Fl and F2 pups/sex/litter], histopathology [10/sex, 0- and 450-ppm exposure groups]) and reproduction (mating, fertility, abortions, premature deliveries, durations of gestation, litter sizes, sex ratios, viabilities, maternal behaviors, reproductive organ weights [also three weanling Fl and F2 pups/sex/ litter], sperm parameters, and implantations. F1 rats were evaluated for age at vaginal patency or preputial separation. Ten P and F1 rats/sex from the 0- and 450-ppm exposure groups and rats at 50 and 150 ppm with reduced fertility were evaluated for histopathology (gross lesions, testes, intact epididymis, all F1 dams for number of primordial follicles). Developmental parameters in offspring included implantation and pup numbers, sexes, viabilities, body weights, gross external alterations, and reproductive parameters (Fl adults). Toxicologically important, statistically significant effects at 150 and/or 450 ppm included mortality and clinical signs associated with reduced absolute and relative water consumption, reduced body weights and weight gains, and reduced absolute and relative feed consumption (P and F1 rats). Significantly reduced body weights at 150 and 450 ppm were associated with reduced organ weights and increased organ weight ratios (% body and/or brain weight). Histopathology did not identify abnormalities. Small delays in sexual maturation (preputial separation, vaginal patency) and more Fl rats with prolonged diestrus were also attributable to severely reduced pup body weights. Mating, fertility, sperm parameters, and primordial ovarian follicular counts were unaffected. The no-observable-adverse-effect level (NOAEL) and the reproductive and developmental NOAELs for BDCM were at least 50 ppm (4.1 to 12.6 mg/kg/day), 5125 to 15,750 times the human adult exposure level, if delayed sexual maturational associated with severely reduced body weights is considered reproductive toxicity. If considered general toxicity, reproductive and developmental NOAELs for BDCM are greater than 450 ppm (29.5 to 109.0 mg/kg/day), or 36,875 to 136,250 times the human adult exposure level. Regardless, these data indicate that BDCM should not be identified as a risk to human reproductive performance or development of human conceptuses.

Oral (drinking water) developmental toxicity studies of bromodichloromethane (BDCM) in rats and rabbits.

Crl:CD(SD)IGS BR VAF/Plus (Crl SD) rats and Hra(NZW) SPF rabbits were tested for potential developmental toxicity from bromodichloromethane (BDCM) provided continuously in the drinking water during gestation (gestation days [GDs] 6 to 21 in rats and GDs 6 to 29 in rabbits). Concentrations of 0, 50, 150, 450, or 900 ppm of BDCM were used for rats; 0, 15, 150, 450, or 900 ppm were used for rabbits (in dose range-finding studies, 1350 ppm was excessively maternotoxic to both species). Investigated maternal parameters included viability, clinical signs, water and feed consumption, and body weights. Maternal gross lesions, gravid uterine weights, abnormal placentas, and numbers of corpora lutea, implantation sites, live and dead fetuses, and early and late resorptions were observed at time of Caesarean sectioning (GD 21 in rats; GD 29 in rabbits). Body weights, sex ratios, and morphological abnormalities (external, soft tissue, and skeletal) were noted in the fetuses. Mean consumed doses of BDCM were calculated to be 0, 2.2, 18.4, 45.0, or 82.0 mg/kg/day for the rats, and 0, 1.4, 13.4, 35.6, or 55.3 mg/kg/day for the rabbits (approximate human intake is 0.8 microg/kg/day [0.0008 mg/kg/day] in adults). In pregnant rats, toxicologically important, statistically significant effects included reduced absolute (g/day) and relative (g/kg/day) water consumption values at > or =50 ppm (2.2 mg/kg/day) and reduced body weight gains (also when corrected for gravid uterine weight) and absolute (g/day) and relative (g/kg/day) feed consumption values at >450 ppm (45.0 mg/kg/day). These parameters were also significantly reduced at > or =450 ppm (35.6 mg/kg/day) in pregnant rabbits (significant weight loss occurred in the rabbits at 900 ppm, i.e., 55.3 mg/kg/day). Thus, the maternal no-observable-adverse-effect level (NOAEL) for BDCM was 150 ppm, i.e., 18.4 and 13.4 mg/kg/day in rats and rabbits, respectively. No adverse effects on embryofetal viability, growth, sex ratio, gross external, soft tissue, or skeletal morphology occurred at 900 ppm in rats or rabbits. Minimal delays in the ossification of forepaw phalanges and hindpaw metatarsals and phalanges occurred in rat fetuses at 900 ppm; delays were considered marginal, reversible, and associated with severely reduced maternal weight gain. Therefore, the developmental NOAEL for rats was 450 ppm (45.0 mg/kg/day), whereas in rabbits it was 900 ppm (55.3 mg/kg/day). These NOAELs are 56,250 and 69,120 times the human adult exposure level of 0.0008 mg/kg/day, respectively. Based on the results of these studies, BDCM should not be identified as a risk to development of human conceptuses.

Biodisposition of dibromoacetic acid (DBA) and bromodichloromethane (BDCM) administered to rats and rabbits in drinking water during range-finding reproduction and developmental toxicity studies.

Dibromoacetic acid (DBA) and bromodichloromethane (BDCM), by-products of chlorine disinfection of water, were provided in drinking water in range-finding reproductive/developmental toxicity studies (rats) and a developmental toxicity study (BDCM) in rabbits. Studies included absorption and biodisposition of DBA and BDCM, including passage into placentas, amniotic fluid, fetuses (rats and rabbits), or milk (rats). The DBA and BDCM range-finding reproductive/developmental toxicity studies each included 50 Sprague-Dawley rats/sex/group. DBA (0, 125, 250, 500, or 1000 ppm) or BDCM (0, 50, 150, 450, or 1350 ppm) was provided in drinking water 14 days premating through gestation and lactation (63 to 70 days). The developmental toxicity range-finding study included 25 time-mated New Zealand white rabbits/group given 0, 50, 150, 450, or 1350 ppm BDCM in drinking water on gestation days (GDs) 6 through 29. Satellite groups (6 male, 17 female rats/group/study and 4 rabbits/group) were used for bioanalytical sampling. Rats and rabbits had exposure-related reduced water consumption caused by apparent taste aversion to DBA or BDCM, especially in the parental animals at the two highest exposure levels (500 and 1000 ppm DBA; 450 and 1350 ppm BDCM). Female rats consumed slightly higher mg/kg/day doses of DBA than male rats, especially during gestation and lactation; weanling rats consumed the highest mg/kg/day doses. DBA produced detectable and quantifiable concentrations in plasma, placentas, amniotic fluid, and milk. Plasma samples confirmed that rats drink predominately during the dark; this drinking pattern, not accumulation, produced detectable plasma concentrations for 18 to 24 hours/day. No quantifiable concentrations of BDCM occurred in plasma, placentas, amniotic fluid, or milk, suggesting that BDCM is rapidly degraded or metabolized in vivo. DBA (500 and 1000 ppm, rats) and BDCM (450 and 1350 ppm, rats and rabbits) produced secondary toxicity in the parental generation by reducing water consumption, which caused severe exposure-related apparent dehydration, reduced feed intake and weight gain. Reproductive and developmental parameters were essentially unaffected (mating possibly reduced [DBA at 1000 ppm]; exposure-related decreases in body weights of pups secondary to reduced water and feed consumption [DBA at 250, 500, and 1000 ppm; BDCM at 150, 450, and 1350 ppm]). No effects on development of rabbit fetuses occurred at BDCM concentrations as high as 1350 ppm. Results from these preliminary studies, in which DBA and BDCM were provided in the drinking water at concentrations thousands of times higher than those to which humans are exposed, suggest that neither DBA nor BDCM are reproductive/developmental risks for humans.

Rat two-generation reproduction and dominant lethal study of acrylamide in drinking water.

Fischer 344 (F344) F(0) weanling rats, 30/sex/group, were exposed to acrylamide in drinking water at 0.0, 0.5, 2.0, or 5.0 mg/kg/day for 10 weeks and then mated. Exposure of F(0) females continued through gestation and lactation of F(1) litters. F(0) males, after F(0) mating, were removed from exposure and mated (one male: two untreated females) for the dominant lethal (DL) assay. Thirty F(l) weanlings/sex/group were exposed for 11 weeks to the same dose levels as their parents, and then mated to produce F(2) offspring. F(0) and F(l) parents and F(1) and F(2) weanlings were necropsied. Prebreeding exposure of F(0) and F(l) animals resulted in systemic toxicity at 2.0 to 5.0 mg/kg/day, with head tilt and/or foot splay increased at 0.5 to 5.0 mg/kg/day. F(0) and F(l) reproductive indices and gestational length were unaffected. Implantations and live pups/litter at birth were reduced at 5.0 mg/kg/day. Survival of F(l) and F(2) pups was reduced at 5.0 mg/kg/day for PND 0 through 4 only. In the DL assay, total and live implants were reduced, pre- and postimplantation loss was increased, and the frequency of DL factors (F(L)%) was increased at 5.0 mg/kg/day. At 5.0 mg/kg/day, adult F(l) male peripheral nerves exhibited axonal fragmentation and/or swelling; F(l) female spinal cord sections were unremarkable. The NOEL for prenatal DL was 2.0 mg/kg/day; the NOEL for adult systemic toxicity, including neurotoxicity, was < or = 0.5 mg/kg/day. Therefore, neurotoxicity and DL were differentially affected.

Developmental toxicity evaluation of inhaled toluene diisocyanate vapor in CD rats.

Mated female CD (Sprague-Dawley) rats, 25/group, were exposed to toluene diisocyanate (TDI) vapor, for six h/day on gestational days (gd) 6 through 15, at 0.00, 0.02, 0.10, or 0.50 p.p.m.. Maternal clinical signs, body weights, and feed and water consumption were recorded throughout gestation. At termination (gd 21), maternal body, gravid uterine, and liver weights were recorded. Corpora lutea were counted, and implantation sites were identified: resorptions and dead and live fetuses. All live fetuses were examined for external alterations. One-half of the live fetuses/litter were examined for visceral (including craniofacial) alterations. The remaining intact fetuses/litter were stained with alizarin red S and examined for ossified skeletal alterations. Maternal toxicity at 0.50 ppm consisted of reduced body weights, body weight gains, feed consumption, and clinical signs of toxicity. Water consumption was unaffected. Gestational parameters exhibited no significant treatment-related changes, including pre- and postimplantation loss, sex ratio/litter, or fetal body weights/litter. Incidences of individual malformations, malformations by category (external, visceral, and skeletal), total malformations, individual external and visceral variations, variations by category, and total variations were unaffected. Of 111 skeletal variants observed, only 1, incidence of poorly ossified cervical centrum 5, was increased at 0.50 ppm, indicating possible minimal fetotoxicity, although it occurred in the absence of any other indications of developmental toxicity. Therefore, exposure to TDI vapor by inhalation, during major organogenesis in CD rats, resulted in maternal toxicity and minimal fetotoxicity at 0.50 ppm no observed adverse effect level (NOAEL) for maternal and developmental toxicity was 0.10 ppm. No treatment-related embryotoxicity or teratogenicity was observed.

Two-generation reproductive toxicity study of inhaled toluene diisocyanate vapor in CD rats.

Twenty-eight 42-day-old pups/sex/group (F0) were exposed to toluene diisocyanate vapor (TDI; 80% 2,4-TDI, 20% 2,6-TDI) by inhalation at 0.0, 0.02, 0.08, or 0.3 ppm, 6 h/day, 5 days/week, for 10 weeks, then mated within groups for 3 weeks, with exposure 7 days/week during mating, gestation, and lactation. F0 maternal animals were not exposed from gestational day (gd) 20 through postnatal day (pnd) 4; maternal exposures resumed on pnd 5. Twenty-eight weanlings/sex/group continued exposure for 12 weeks (starting on pnd 28) and were bred as described above. F0 and F1 parents and ten F1 and F2 weanlings/sex/group were necropsied, and adult reproductive organs, pituitary, liver, kidneys, and upper respiratory tract (target organs) were evaluated histologically in ten/sex/group. Adult toxicity was observed in both sexes and generations at 0.08 and 0.3 ppm, including occasional reductions in body weights and weight gain, clinical signs of toxicity at 0.08 and 0.3 ppm, and histologic changes in the nasal cavities at 0.02, 0.08, and 0.3 ppm (including rhinitis, a nonspecific response to an irritating vapor, at all concentrations). There was no reproductive toxicity, reproductive organ pathology, or effect on gestation or lactation at any exposure concentration. Postnatal toxicity and reduced body weights and weight gains during lactation occurred only in F2 litters at 0.08 and 0.3 ppm. Therefore, under the conditions of this study, a no observed adverse effect level (NOAEL) was not determined for adult toxicity; the NOAEL for reproductive toxicity was at least 0.3 ppm, and the NOAEL for postnatal toxicity was 0.02 ppm.

Developmental toxicity evaluation of methyl tertiary-butyl ether (MTBE) by inhalation in mice and rabbits.

Pregnant CD-1 mice (30 per group) and female New Zealand White rabbits (15 per group) were exposed by inhalation to 0, 1000, 4000 and 8000 ppm methyl tertiary-butyl ether (MTBE) vapor for 6 h a day during gestational days (GD) 6-15 and 6-18, respectively. Maternal body weights, clinical observations and food consumption were recorded throughout gestation for both species. At scheduled euthanization (GD 18 for mice and GD 29 for rabbits), fetuses were weighed, sexed and examined for external, visceral (including craniofacial) and skeletal alterations. For both species, the pregnancy rate was high and equivalent across all groups; no pregnant animals died or aborted. There were no does that delivered early, but there were three mouse dams in the control group and two dams in the 4000 ppm group that delivered early and were removed from the study. In mice, maternal body weights, body weight gain, corrected maternal gestational weight change and food consumption were significantly reduced in mice at 8000 ppm. Hypoactivity and ataxia were observed in dams exposed to 4000 and 8000 ppm. Gestational parameters affected at 8000 ppm included post-implantation loss (due to increased late resorptions and dead fetuses) and altered sex ratio (decreased males); fetal body weights per litter were reduced at 4000 and 8000 ppm. There was a significantly increased incidence of cleft palate at 8000 ppm; this resulted in increased incidences of pooled external and visceral malformations and of total malformations at this exposure concentration. There were also treatment-related increases in the incidence of individual skeletal variations at 4000 and 8000 ppm. In rabbits, maternal weight gain and food consumption were significantly reduced at 4000 and 8000 ppm. Relative liver weights were also reduced at 8000 ppm. All gestational parameters were equivalent across all groups, including pre- and post-implantation loss, fetal sex ratios, litter size and fetal weights/litter. There was no evidence of treatment-related teratogenicity observed at any dose tested in rabbits. The no-observed-effect levels (NOELs) for maternal and developmental toxicity were both 1000 ppm in mice and 1000 ppm and at least 8000 ppm, respectively, in rabbits.

Two-generation reproductive toxicity study of methyl tertiary-butyl ether (MTBE) in rats.

A two-generation reproductive toxicity study of methyl tertiary-butyl ether (MTBE) was conducted in Sprague-Dawley rats. Twenty-five rats of each sex (F0) were exposed by inhalation to 0, 400, 3000 or 8000 ppm MTBE vapor, 6 h a day for 10 weeks prior to mating. Parental animals were then mated within groups for up to 3 weeks. Parental females were exposed during mating, gestation and lactation (starting on day 5); parental males were exposed during mating through delivery of their last litter sired. The F1 adults were selected from the F1 litters and were exposed beginning on postnatal day 28 for at least 8 weeks before mating to produce F2 litters. During exposures to 3000 and 8000 ppm MTBE, group observations included hypoactivity and lack of startle reflex in parental animals from both generations. Parental animals at 8000 ppm were also ataxic. During the pre-mating period, body weights of the 8000 ppm males from both generations and the F1 females were significantly reduced compared to control animals. Transient body weight reduction was also observed in the 3000 ppm F1 males and females during the pre-mating period. Lactational body weights were increased in the 8000 ppm females from both generations. In the F1 generation, increased liver weights were noted in the 3000 and 8000 ppm animals for both sexes, although histopathological examination revealed no treatment-related effects. There were no treatment-related reproductive effects noted in any of the parameters measured in this study. Offspring survival was equivalent among treated and control groups from both generations, and there were no remarkable post-mortem findings. There was, however, a significant increase in dead F2 pups in the 8000 ppm group on postnatal day 4. The F1 litters at 3000 and 8000 ppm had lowered body weights from postnatal days 14-21 and 14-28, respectively. The F2 generation of pups at 3000 and 8000 ppm also exhibited lowered body weights from postnatal days 14-28 and 7-28, respectively. Body weight gains in both the F1 and F2 litters were also reduced for the corresponding time intervals. Thus, exposure to MTBE vapor produced no reproductive toxicity to two generations of Sprague-Dawley rats even in the presence of parental toxicity at 3000 and 8000 ppm. Postnatal toxicity was observed in the offspring of both generations, but only in the presence of maternal toxicity. The no-observed-effect level (NOEL) for both parental and postnatal toxicity is 400 ppm, and the NOEL for reproductive toxicity is at least 8000 ppm.

Assessment of the developmental toxicity of ethylene glycol applied cutaneously to CD-1 mice.

Ethylene glycol (EG; CAS No. 107-21-1) is teratogenic to mice by whole-body exposure to an aerosol at high concentrations, but results were confounded by possible exposure from ingestion after grooming and/or from percutaneous absorption. Therefore, CD-1 mice were exposed to EG on Gestational Days (GD) 6 through 15, 6 hr/day by occluded cutaneous application at 0, 12.5, 50, or 100% (undiluted) EG (0.1 ml/animal, equivalent to approximately 0, 404, 1677, or 3549 mg/kg/day [10 ml/kg, positive control gavage (PCGG)], 30 females/group. Dams were weighed and evaluated daily (including application site) for clinical signs and water consumption throughout gestation. On GD 18, maternal uterus, liver, and paired kidneys were weighed; kidneys of 0 and 100% and the PCGG were examined microscopically. Corpora lutea and implantation sites were recorded. Live fetuses were weighed, sexed, and examined for structural alterations. For cutaneously exposed dams, there was no treatment-related maternal, no differences in pre- or postimplantation loss in fetal body weights/litter, and no increased incidences of any fetal malformations. Two skeletal variations, increased at 100% may represent effects of restraint stress and/or findings due to chance. In the PCGG, 8 females (26.7%) died, water consumption was increased, fetal body weights/litter were reduced, and fetal malformations and variations were increased. PCGG kidneys exhibited tubular nephrosis and tubular cell degeneration, with no oxalate crystals, documenting renal toxicity at this oral dose in mice. Minimal-grade renal tubular lesions observed in 3 mice (of 30) at 100% EG may represent treatment-related or incidental findings. Therefore, exposure of pregnant CD-1 to 0, 12.5, 50 or 100% EG during organogenesis by occluded cutaneous application resulted in minimal or no observable maternal or developmental toxicity at 100% (approximately 3549 mg/kg/day), the NOEL.

Determination of a no-observed-effect level for developmental toxicity of ethylene glycol administered by gavage to CD rats and CD-1 mice.

Previous studies have indicated that ethylene glycol (EG) is a developmental toxicant in rats and mice primarily when ingested. This study was designed to establish no-observed-effect levels (NOELs) for developmental toxicity of EG administered by gavage in both rodent species. Dams were administered EG on Gestation Days 6-15; rats were given 0, 150, 500, 1000, or 2500 mg EG/kg/day; mice were dosed with 0, 50, 150, 500, or 1500 mg EG/kg/day. In rat dams given 2500 mg EG/kg/day, water consumption was increased during treatment and body weights were reduced throughout gestation; liver and kidney weights were increased at euthanization (Gestation Day 21). Relative liver weights were also increased at 1000 mg/kg/day. Effects observed in rat fetuses at 2500 mg/kg/day included the following: hydrocephaly; gastroschisis; umbilical hernia; fused, duplicated, or missing arches, centra, and ribs; poor ossification in thoracic and lumbar regions; and reduced body weights. Reduced body weights, duplicated or missing ribs, centra, and arches, and poor ossification were also observed in rat fetuses at 1000 mg/kg/day. In mice, there was no apparent treatment-related maternal toxicity. In mouse fetuses (Gestation Day 18), effects were observed at 1500 mg/kg/day and included reduced body weights, fused ribs and arches, poor ossification in thoracic and lumbar centra, and increased occurrence of an extra 14th rib. At 500 mg/kg/day, slight reductions in fetal body weight and increased incidences of extra ribs were observed. Under conditions of these studies, NOELs for developmental toxicity were 500 mg/kg/day for rats and 150 mg/kg/day for mice, indicating that mice were more susceptible than rats to the teratogenic effects of EG.

Evaluation of the developmental toxicity of ethylene glycol aerosol in CD-1 mice by nose-only exposure.

Ethylene glycol (EG; CAS No. 107-21-1) is teratogenic to mice by whole-body (WB) exposure to aerosol (1000-2500 mg/m3). The WB results were confounded by possible exposure from ingestion after grooming and/or from percutaneous absorption. Therefore, CD-1 mice were exposed to EG aerosol (MMAD 2.6 +/- 1.7 microns) on Gestational Days (GD) 6 through 15, 6 hr/day, by nose-only (NO) (0, 500, 1000, or 2500 mg/m3) or WB exposures (0 or 2100 mg/m3, as positive control), 30/group. Five additional "satellite" females each at 2500 mg/m3 NO and 2100 mg/m3 WB were exposed on GD 6 for measurement of EG on fur. Control environments were water aerosol (4200 mg/m3 for NO; 2700 mg/m3 for WB). Females were weighed and evaluated for clinical signs and water consumption throughout gestation. On GD 18, maternal uterus, liver, and kidneys (2) were weighed, with kidneys examined microscopically. Corpora lutea and implantation sites were recorded. Live fetuses were weighed, sexed, and examined for structural alterations. For NO dams, kidney weights were increased at 1000 and 2500 mg/m3; no renal lesions and no other treatment-related maternal toxicity were observed. There were no effects on pre- or postimplantation loss; fetal body weights/litter were reduced at 2500 mg/m3. At 2500 mg/m3, incidences of fused ribs and skeletal variations were increased. The 2500 mg/m3 NO satellite animals had approximately 330 mg/kg extractable EG. The WB group exhibited maternal and developmental toxicity including increased fetal skeletal malformations and variations, confirming previous results, with 1390 mg/kg extractable EG on fur. Therefore, exposure of CD-1 mice to a respirable EG aerosol during organogenesis by NO inhalation resulted in minimal maternal toxicity at 1000 and 2500 mg/m3 and developmental toxicity at 2500 mg/m3. The NOAEL was 500 mg/m3 NO for maternal and 1000 mg/m3 NO for developmental toxicity. This study supports the interpretation of the initial EG WB results as due to systemic exposure from noninhalation routes since limiting noninhalation routes prevented almost all of the effects (including teratogenicity) observed in mice after WB exposure.

Missed slipped capital femoral epiphysis: illustrative cases and a review.

Slipped capital femoral epiphysis (SCFE) is a fairly common condition affecting older children and adolescents, and has the potential for long-term, crippling sequelae. Early recognition is the single most important controllable factor, but the diagnosis is often missed or delayed, resulting in progression of the slip. A SCFE should be suspected and promptly evaluated in any older child or adolescent presenting with a limp or complaints of hip, groin, thigh, or knee pain, especially if the patient is overweight. The diagnosis is usually made by anteroposterior and frog-leg lateral radiographs of the hips. Common errors at initial presentation include: not obtaining hip radiographs (due to either no hip pain or the lack of an impressive history and physical findings); misreading hip radiographs (the findings can be subtle); and lack of timely referral. Early involvement of and treatment by an orthopedic surgeon can greatly reduce the potential complications. We present three cases of SCFE that highlight common errors made at initial presentation, and a discussion that includes the differential diagnosis of an older child or adolescent with a painful limp.

Evaluation of the developmental toxicity of ethylene glycol aerosol in the CD rat and CD-1 mouse by whole-body exposure.

Ethylene glycol (EG) is a major industrial chemical, shown to be teratogenic at high doses by gavage in rodents. Since one route of industrial exposure is to the aerosol at high concentrations, timed-pregnant CD rats and CD-1 mice were exposed, whole-body, to a respirable aerosol of EG (mass median aerodynamic diameter, 2.3 microns) on Gestational Days (GD) 6 through 15 for 6 hr per day at target exposure concentrations of 0, 150, 1000, or 2500 mg/m3 (analytical concentrations of 0, 119 +/- 13, 888 +/- 149, and 2090 +/- 244 mg/m3, respectively), with 25 plug-positive animals per species per group. Clinical observations and maternal body weights were documented throughout gestation for both species. Maternal food and water consumption was measured in rats only throughout gestation. At scheduled necropsy (GD 21 for rats, GD 18 for mice), maternal animals were evaluated for body weight, liver weight, kidney weight, gravid uterine weight, number of ovarian corpora lutea, and status of implantation sites, i.e., resorptions, dead fetuses, live fetuses. Fetuses were dissected from the uterus, counted, weighed, sexed, and examined for external, visceral, and skeletal malformations and variations. All rat dams survived to scheduled termination. Minimal maternal toxicity was indicated by a significant increase in absolute and relative liver weight at 2500 mg/m3. Food and water consumption, maternal body weights and weight gain, and maternal organ weights (other than liver) were unaffected by exposure. Gestational parameters were unaffected by exposure, including pre- and post-implantation loss, live fetuses/litter, sex ratio, and fetal body weight/litter. There was no treatment-related increase in the incidence of any individual malformation, in the incidence of pooled external, visceral, or skeletal malformations, or in the incidence of total malformations by fetus or by litter. There were no increases in the incidence of external or visceral variations. Evidence of fetotoxicity, expressed as reduced ossification in the humerus, the zygomatic arch, and the metatarsals and proximal phalanges of the hind-limb, was observed at 1000 and 2500 mg/m3. All mouse dams survived to scheduled termination. One dam at 2500 mg/m3 was carrying a totally resorbed litter at termination. Maternal toxicity was observed at 1000 and 2500 mg/m3, expressed as reduced body weight and weight gain during and after the exposure period, and reduced gravid uterine weight. (Maternal effects may have been due, in part or whole, to effects on the conceptuses; see below.)(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of exposure to water aerosol or air by nose-only or whole-body inhalation procedures for CD-1 mice in developmental toxicity studies.

This study was performed to evaluate the effects of nose-only restraint versus whole-body exposure procedures in the absence of test chemical, and to determine the appropriate control environment (water aerosol or air) for subsequent developmental toxicity studies of test materials administered as aerosols. Timed-pregnant CD-1 mice, 30/group, were exposed to high concentrations of water aerosol or to air by whole-body or nose-only inhalation procedures on Gestational Days (GD) 6 through 15 for 6 hr per day. The group exposed to air by whole-body procedures was designated as the control group. Clinical observations and maternal body weights were recorded throughout gestation. At scheduled necropsy on GD 18, maternal animals were evaluated for body weight, gravid uterine weight, liver weight, number of ovarian corpora lutea, and status of uterine implantation sites. Fetuses were counted, weighed, and sexed and were examined for external, visceral (including craniofacial), and skeletal alterations. Indices of maternal toxicity were affected in both nose-only groups. Maternal body weights were reduced during and after the exposure period; maternal weight gain was reduced during the exposure period. Clinical signs observed, from animals struggling during restraint, were resolved by GD 18. At sacrifice on GD 18, maternal body weights and maternal gestational weight gains (both corrected for gravid uterine weights) and absolute liver weights were reduced in both nose-only groups. Four females died (13.3%, all pregnant) in the air nose-only group, and maternal liver weight (relative to body weight) was reduced in the aerosol nose-only group. Gestational parameters were unaffected by any of the treatments. There were no statistically significant differences in the incidences of any individual malformations or malformations by category (external, visceral, or skeletal) or of total malformations. However, exencephaly, low set ears, cleft palate and ventricular septal defect were observed only in both aerosol-exposed groups (whole-body and nose-only exposed). The incidences of individual external or visceral variations or of variations by category or of total variations were unaffected. The incidence of one skeletal variation, poorly ossified supraoccipital skull bone, was significantly increased in the aerosol nose-only group relative to the air whole-body controls. There were also increased incidences (not statistically significant) of extra (14th) ribs in both aerosol groups. Therefore, maternal restraint (in both nose-only groups) during organogenesis produced indications of maternal toxicity, but restraint did not appear to affect normal embryo/fetal morphologic development.(ABSTRACT TRUNCATED AT 400 WORDS)

Teratologic evaluations of N,N-diethyl-m-toluamide (DEET) in rats and rabbits.

The potential for DEET to produce developmental toxicity was evaluated in Charles River CD rats and New Zealand White rabbits. Rats were administered undiluted DEET by gavage on Gestational Days (gd) 6-15 at dosage levels of 0, 125, 250, and 750 mg/kg/day. Rabbits were administered undiluted DEET by gavage on gd 6-18 at dosage levels of 0, 30, 100, and 325 mg/kg/day. Group sizes were 25 females per group for rats and 16 females per group for rabbits. Control rats and rabbits were administered corn oil at the same dosage volumes administered in the high-dose DEET groups. In rats, maternal toxicity in the form of clinical signs including two deaths and depressed body weight and food consumption was observed at the high-dose level of 750 mg/kg/day. Rat fetal body weights per litter also were reduced at 750 mg/kg/day. In rabbits, maternal toxicity in the form of depressed body weight and food consumption was observed at the high-dose level of 325 mg/kg/day. No maternal toxicity was observed at the low- or mid-dose groups for rats or rabbits. With the exception of the reduced fetal weights in rats at 750 mg/kg, there was no evidence of fetal toxicity, no effects on any of the gestational parameters, nor were there any treatment-related increases in external, visceral, or skeletal variations or malformations in the offspring from the rats and rabbits from these studies.