Using physiologically based pharmacokinetic modeling and benchmark dose methods to derive an occupational exposure limit for N-methylpyrrolidone.

The developmental effects of NMP are well studied in Sprague-Dawley rats following oral, inhalation, and dermal routes of exposure. Short-term and chronic occupational exposure limit (OEL) values were derived using an updated physiologically based pharmacokinetic (PBPK) model for NMP, along with benchmark dose modeling. Two suitable developmental endpoints were evaluated for human health risk assessment: (1) for acute exposures, the increased incidence of skeletal malformations, an effect noted only at oral doses that were toxic to the dam and fetus; and (2) for repeated exposures to NMP, changes in fetal/pup body weight. Where possible, data from multiple studies were pooled to increase the predictive power of the dose-response data sets. For the purposes of internal dose estimation, the window of susceptibility was estimated for each endpoint, and was used in the dose-response modeling. A point of departure value of 390 mg/L (in terms of peak NMP in blood) was calculated for skeletal malformations based on pooled data from oral and inhalation studies. Acceptable dose-response model fits were not obtained using the pooled data for fetal/pup body weight changes. These data sets were also assessed individually, from which the geometric mean value obtained from the inhalation studies (470 mg*hr/L), was used to derive the chronic OEL. A PBPK model for NMP in humans was used to calculate human equivalent concentrations corresponding to the internal dose point of departure values. Application of a net uncertainty factor of 20-21, which incorporates data-derived extrapolation factors, to the point of departure values yields short-term and chronic occupational exposure limit values of 86 and 24 ppm, respectively.

Vitamin E succinate enhances steatotic liver energy status and prevents oxidative damage following ischemia/reperfusion.

We have previously shown that treatment of steatotic livers with vitamin E succinate decreases liver injury and increases survival after ischemia/reperfusion (I/R). It is now understood that compromised energy status is associated with increased injury following liver ischemia in the setting of hepatic steatosis at least partially as a result of increased reactive oxygen species (ROS) and induction of mitochondrial uncoupling protein-2 (UCP2). Given the association between ROS, mitochondrial function, and UCP2, it was our goal to determine whether the protective effects of vitamin E succinate were associated with decreased ROS injury, down-regulation of UCP2, or improvement of ATP levels following I/R. To test this, leptin deficient (ob/ob) mice with steatotic livers that had received other 50 IU of vitamin E succinate supplement per day or control chow for 7 days were subjected to total hepatic ischemia (15 minutes) followed by reperfusion. We measured liver expressions of ATP, glutathione (GSH), and UCP2 as well as mitochondrial DNA damage. Vitamin E treatment decreased hepatic UCP2 expression and increased ATP and GSH levels prior to I/R. These levels were maintained at 1 hour after I/R. At 24 hours, while hepatic UCP2 expression, ATP, and GSH levels were similar to those of mice not receiving vitamin E, mitochondrial DNA damage was blocked. These results revealed that vitamin E succinate decreased hepatic UCP2 expression, reduced oxidative stress, and improved mitochondrial function in mice with steatotic livers before and after I/R, identifying mechanisms of protection in this setting.

Effects of polyvinyl alcohol administered in the diet to rats on fertility, early embryonic development, growth and development.

PVA was administered in the diet to male and female Sprague-Dawley rats (26/sex/group) at doses of 0, 2000, 3500 and 5000 mg/kg/day for two generations. The study design assessed gonadal function, estrous cycle, mating behavior, conception, gestation, parturition, lactation, weaning, and growth and development of F(1) and F(2) offspring. Parental rats were treated for 70 days prior to mating, throughout mating, gestation and lactation until sacrifice. Clinical observations, body weights and feed consumption were recorded routinely. Dietary concentrations were adjusted for each sex on a weekly basis except during gestation and lactation, to provide the intended mg/kg/day PVA levels. Pups were weighed routinely and weaned at 21 days of age prior to selection for the next generation. Unformed stool was noted predominately at the 3500 and 5000 mg/kg/day levels in P(0) and F(1) parental animals. This finding was attributed to the high levels of PVA being fed and subsequently excreted in the stool. Slight decreases in the mean body weights of P(0) males were noted at 2000 and 5000 mg/kg/day. Feed consumption was elevated at the 3500 and 5000 mg/kg/day doses in both generations but not during either lactation period. These increases generally were observed in a dose-related manner (g/kg/day), as a result of the large amount of PVA being consumed to maintain the caloric intake necessary for normal growth. There were no effects of PVA on P(0), F(1) male or female reproductive performance or pup survival, growth, organ weights, and macroscopic or microscopic observations at doses of 2000, 3500 and 5000 mg/kg/day. Therefore the no-observed-effect level (NOAEL) is 5000 mg/kg/day for both parental and offspring in this reproductive study.

Efficient discovery of inhibitory ligands for diverse targets from a small combinatorial chemical library of chimeric molecules.

Living systems are mainly composed and regulated by compounds in four biochemical classes and their polymers-nucleotides, carbohydrates, lipids, and amino acids. Early combinatorial chemistry libraries consisted of peptides. The present report describes the general bioactivity and biophysical properties of a combinatorial chemical library that used glyco, nucleotidyl, and lipid building blocks. The resulting chimeric combinatorial library of 361 compounds had a confirmed cumulative hit rate of 0.16%, which is 8-fold higher than a commonly claimed industrial benchmark of 0. 02%. It produced 7 structurally confirmed hits for a third of 12 proprietary drug discovery projects, and these comprised a variety of molecular targets. Diversity analyses demonstrated that despite the small number of compounds, a wider range of diversity space was covered by this library of biochemical chimeras than by a branched tripeptide library of the same size and similar generic formula.

Gender-dependent differences in hepatic tumor promotion in diethylnitrosamine initiated infant B6C3F1 mice by alpha-hexachlorocyclohexane.

Chronic exposure of B6C3F1 mice to phenobarbital (PB), subsequent to a single initiating dose of diethylnitrosamine (DENA) at 15 d of age, has been previously shown to inhibit hepatic tumorigenesis in male mice, while promoting hepatic tumor formation in female mice (Weghorst & Klaunig, 1989). In the present study, the effects of another hepatic tumor promoter, alpha-hexachlorocyclohexane (alpha-HCH), in similarly initiated B6C3F1 mice was investigated. Male and female mice received a single intraperitoneal (ip) injection of either DENA or saline at 15 d of age. Beginning at 28 d of age, the mice received either alpha-HCH in the diet (250 ppm) or untreated basal diet. Like PB, alpha-HCH inhibited hepatic tumorigenesis in male mice, while promoting hepatic tumor formation in female mice following chronic exposure. In an additional experiment, already formed preneoplastic hepatic foci in male and female B6C3F1 mice were examined for their responsiveness to the induction of DNA synthesis by alpha-HCH treatment. The mice received a single ip injection of DENA at 15 d of age to induce hepatocellular foci. Beginning at 24 wk of age, mice received either basal diet or diet containing 250 ppm alpha-HCH for 7 consecutive d. DNA synthesis was assessed by continuous [3H]thymidine infusion via subcutaneously implanted osmotic minipumps. In female mice treated with alpha-HCH, DNA synthesis in hepatocellular foci was increased substantially compared to untreated females. In contrast, male mice receiving alpha-HCH showed no increase in DNA synthesis in hepatocellular foci from that seen in non-alpha-HCH-treated males. Based on these results, we postulate that the gender-dependent differences in hepatic tumorigenesis observed in B6C3F1 mice initiated during infancy may be related to chemical tumor promoter modulation of the normal hormonal environment, or to differences in the ability of hepatocellular foci to respond to the induction of DNA synthesis by the tumor promoter.

Interdisciplinary management of hemicorporectomy after spinal cord injury.

Hemicorporectomy (HCP) is infrequently used, but its effects can devastate the patient's body image, autonomic function, and physical abilities even more than a spinal cord injury of comparable level. Interdisciplinary management is of the utmost importance. This report describes the 2 year course, including four separate rehabilitation admissions, of a patient who was initially paraplegic, and then underwent a HCP for complications secondary to a cauda equina ependymoma. The patient's expectations for functional independence were established by his successful initial spinal cord rehabilitation. The HCP was performed 6 months after initial discharge secondary to infected Harrington rods and rapid spread of the tumor. Extensive use of the interdisciplinary team approach allowed comprehensive analysis and treatment of the patient's comfort, mobility, skin tolerance, and upper extremity functional abilities. Four successive prostheses were developed and modified, until all concerns were successfully addressed. The patient ultimately became completely independent at the wheelchair level. The evaluations, treatment plan, and emphasis of each discipline, including physical therapy, occupational therapy, rehabilitation nursing, therapeutic recreation, social work, vocational rehabilitation, and physiatry are summarized. Differences between the patient's course and standard spinal cord rehabilitation are detailed.

Teratogenic assessment of 2,4-dichlorophenol in Fischer 344 rats.

The potential maternal, embryotoxic, and teratogenic parameters of 2,4-dichlorophenol (2,4-DCP) were evaluated in Fischer 344 rats following oral administration in corn oil on Days 6 through 15 of gestation. Dose levels were 0, 200, 375, and 750 mg/kg/day. Females were sacrificed on Gestation Day 20 and cesarean sections performed. The fetuses were weighed, sexed, measured for crown-rump length, and examined for external malformations. A skeletal examination was conducted on one-half of the fetuses after staining with alizarin red S. The remaining fetuses were fixed in Bouin's solution and examined for visceral anomalies and developmental variations. Maternal body weight gain inhibition occurred in all 2,4-dichlorophenol-treated groups during the treatment period. Four treatment-related deaths occurred in the 750 mg/kg/day group. Additional indicators of maternal toxicity included urogenital staining of the fur at all levels tested, and an increased incidence of hair loss and respiratory rales at the 750 mg/kg/day level. Fetal examinations did not reveal differences in the incidence of external, visceral, or skeletal fetal malformations in any treatment group, when compared with the control group. A slight increase in early embryonic death occurred in the high-dose group only. Fetal weights were lower in the high-dose group than in the control group. Variations in skeletal structure were expressed among fetuses exposed to 750 mg/kg/day during organogenesis. These included delayed ossification of sternal elements and vertebral arches. The reduced fetal weights, intrauterine survival, and retarded ossification may represent a slight degree of embryotoxicity or fetotoxicity in this group. The test material was not teratogenic at any dose level.

Teratology and multigeneration reproduction studies with maleic anhydride in rats.

These studies were initiated to evaluate the effects of maleic anhydride on development and reproduction in CD rats. In the teratology study, pregnant rats (19-23/group) received 0, 30, 90, or 140 mg/kg/day maleic anhydride in corn oil orally from Days 6-15 of gestation and fetuses were examined for gross soft tissue and skeletal defects. A reduced weight gain or weight loss was observed in all maleic anhydride-treated groups between Days 6 and 9; however, mean weights of all groups were within 5% of control on Days 15 and 20. No treatment-related effects on fetal development were observed. In the multigeneration study, rats (10 males and 20 females/group) received 0, 20, 55, or 150 mg/kg/day maleic anhydride in corn oil orally and were mated to produce two generations, each with two litters. Groups of the same size from the second litter were used for subsequent generations and were given the same dose of maleic anhydride as were their parents. The high-dose group was terminated during the second generation due to treatment-related mortality in adults. Renal cortical necrosis occurred in high-dose Fo males and females. Increased kidney weights were observed in low- and mid-dose adult F1 females. No treatment-related effects on reproduction were observed with maleic anhydride at doses up to 55 mg/kg/day over two generations.

A subchronic, teratologic, and dominant lethal study of 2-methylresorcinol in rats. II. Teratologic and dominant lethal study.

2-Methylresorcinol (2-MR) was administered to groups of 40 male and 35 female Sprague-Dawley rats by admixture with the diets at levels of 0.1, 0.4, and 1.5% (see Part I; T.H. Re, R.F. Loehr, S.C. Rodriguez, C.E. Gilmore, and C.M. Burnett, 1986, Fundam. Appl. Toxicol. 7, 287-292). Following 90 days of exposure, 25 randomly selected females in each group were mated to untreated males in a teratology study in which exposure to 2-MR continued throughout the gestation period. After 20 weeks of exposure to 2-MR, 20 males per group were removed from the test diets containing 2-MR and were mated to untreated females in a dominant lethal study. Feeding 2-MR at levels of 0.4 and 1.5% in the diet was associated with a significant reduction in body weight gain. 2-MR was not teratogenic nor did it induce a dominant lethal effect under the conditions of this study.

Teratogenicity studies of alkylaryl phosphate ester plasticizers in rats.

Santicizer 141 plasticizer (2-ethylhexyldiphenyl phosphate) and Santicizer 148 plasticizer (isodecyldiphenyl phosphate) were tested for teratogenic activity in Charles River COBS CD rats. Groups of 25 mated females were given 0, 300, 1000, or 3000 mg/kg/day by gavage on Days 6 through 15 (Santicizer 141) or 6 through 19 (Santicizer 148) of gestation. Mean maternal body weight gains were slightly and severely reduced at the mid- and high-dose levels of Santicizer 141, respectively. Body weights were not affected by treatment with Santicizer 148. Most malformations found in groups treated with either plasticizer occurred as single incidences and have been observed in historical controls. Thus, no teratogenic response was observed in rats after treatment with either of these two alkylaryl phosphates during the period of organogenesis.

Evaluation of the teratogenic potential of three aliphatic nitriles in the rat.

Acetonitrile (ACN), adiponitrile (ADN), and propionitrile (PN), were evaluated for embryotoxic and teratogenic potential in rats. Mated Sprague-Dawley rats were administered one of the three nitriles by gavage on gestation Days 6-19, inclusive. Daily dosage levels (mg/kg body wt) were: ACN at 0, 125, 190, and 275; ADN at 0, 20, 40, and 80; PN at 0, 20, 40, and 80. There was evidence of maternal toxicity in each of the high dose groups treated with ACN, ADN, or PN. Some maternal effects also were seen with ADN at the middle dosage. Embryotoxic effects were observed at the highest dosage tested for ACN and middle and high dose levels for PN. Slight fetotoxicity was observed at the highest dosage for ADN. No teratogenic effects were observed at any dosage level with ACN, ADN, or PN.

Teratology of intravaginally administered contraceptive jelly containing octoxynol-9 in rats.

Octoxynol-9, a nonionic surfactant used as a spermicidal agent in ORTHO-GYNOL (registered trademark) Contraceptive Jelly (Ortho Pharmaceutical Corporation, Raritan, NJ), was administered intravaginally to pregnant Sprague Dawley COBS CD rats at dosages of 0.5 mg/kg/day and 5 mg/kg/day (two-thirds and six times the clinical dosage) on days 6-15 of gestation in order to assess its teratogenic potential. Untreated, sham, and vehicle control groups were also incorporated into the study protocol. No meaningful differences were observed between the treated and control groups in maternal toxicity, maternal reproductive parameters, fetal toxicity, and the incidence of external, visceral, and skeletal malformations or developmental variations. It is concluded that octoxynol-9 is not embryotoxic or teratogenic when administered intravaginally to rats during organogenesis.

Results of teratogenicity testing of m-aminophenol in Sprague-Dawley rats.

meta-Aminophenol (m-AP) was administered in the diet to female Sprague-Dawley rats for a period of at least 90 days at levels of 0.1, 0.25, and 1.0%. In the 0.25% group a significant reduction in body weight was noted, in comparison with control values, and in the 1.0% group a significant reduction in both body weight and food consumption was noted. Ten of the rats in each group were necropsied. Deposition of iron positive pigment in the spleen, liver, and kidney combined with decreased red blood cell count and hemoglobin and increased mean corpuscular volume indicated a hemolytic effect. There were also morphologic changes in the thyroid which were consistent with hyperactivity. The remaining 25 rats in each group were removed from m-AP treatment and immediately mated to untreated males of the same strain. After the mating period the dams again were given m-AP for the duration of gestation. All dams were killed on Day 20 of gestation; one-third of the fetuses were examined for visceral malformations and two-thirds for skeletal malformations and variations. An additional significant reduction in body weight gain was noted during gestation in the 1.0% group as compared to the control group. There were no other adverse dose-related findings demonstrated in the reproduction performance of the dams or in the survival or development of their offspring. Therefore, although maternal toxicity was demonstrated at the highest dose level, there was no evidence of teratogenic or embryofetal toxicity at any dose level tested.

Evaluation of the teratogenic potential of the oxidative dye N-phenyl-para-phenylenediamine.

The oxidative dye N-phenyl-para-phenylenediamine was evaluated for teratogenic potential. The dye was administered by gavage to pregnant Sprague-Dawley rats at dose levels of 50, 100, and 200 mg/kg on gestation days six through fifteen. No signs of toxicity were observed during the treatment period. A significant reduction in mean maternal weight gain was noted during treatment at the high dose level of 200 mg/kg. The test material did not produce embryotoxic nor fetal toxic effects at dose levels utilized. Evaluation of fetal external, visceral, and skeletal anomalies revealed no statistically significant differences between dye treated and control groups. Oral exposure of dams to the positive control, Vitamin A, resulted in a significant increase in the number of litters with fetuses having external, visceral, and skeletal anomalies.

Preclinical toxicology studies with acyclovir: teratologic, reproductive and neonatal tests.

Five studies were done to define the potential of Acyclovir (ACV), a new nucleoside analog for antiviral chemotherapy, to produce adverse effects on reproduction and development in laboratory animals. ACV produced no adverse effects when given by gavage to F0 generation mice at 50, 150 and 450 mg/kg/day in a two generation reproduction/fertility study. Some mice were evaluated for teratologic effects and others for postnatal development, including behavior, with negative results. ACV was not embryotoxic and did not increase the incidence of fetal malformations when given by subcutaneous injection to pregnant rats and rabbits at dose levels of 12, 25 and 50 mg/kg/day during the periods of major organogenesis. A comparative LD50 study revealed that 3-day-old rats were not more sensitive to acute toxic effects of ACV than more mature rats. Finally, in a comprehensive multidose toxicity study ACV was given subcutaneously to neonatal rats at 5, 20 and 80 mg/kg/day for 19 consecutive days. There was minimal effect on body weight gain in neonates treated at 20 mg/kg/day and a significant decrease in body weight gain at 80 mg/kg/day. Minimal renal lesions occurred at 80 mg/kg/day but no other signs of adverse effects on developing organ systems were observed. Except for decreased body weight gain in neonatal rats treated at 80 mg/kg/day, ACV did not produce adverse effects on mammalian development when tested in a variety of preclinical toxicology studies.

The absence of teratogenic hazard potential of p-phenylenediamine in Sprague-Dawley rats.

Para-phenylenediamine (PPD) was administered by gavage to pregnant Sprague-Dawley Rats at dose levels of 5, 10, 15, 20, and 30 mg/kg/day on days 6 through 15 of gestation (day 0 = day sperm was found in the vagina). A sham control group and a pair fed control group were studied at the same time. Pregnant animals were killed on day 20 of gestation and 1/3 of the fetuses were examined for visceral malformations and 2/3 for skeletal malformations and variations. Significant reductions in food consumption and weight gain were noted in the 30 mg/kg and pair fed control groups. Two pregnant rats given PPD at 30 mg/kg/day died but there were no deaths in any other dose groups. Fetal evaluations showed no biologically or statistically significant increase in malformations or developmental variations in any group. Therefore, although maternal toxicity was demonstrated at the two highest dose levels, there was no evidence of teratogenic or other embryotoxic effects.