Development of potent aldose reductase inhibitors having a hydantoin structure

Seventeen hydantoin derivatives were tested as inhibitors of aldose reductase, an enzyme believed to participate in the initiation of diabetic complications. Nine compounds with high inhibitory activities (IC50 values against purified rat lens aldose reductase less than or equal to 1.06 X 10(-6)M) were tested further for their abilities to prevent sorbitol accumulation induced by exposure of excised rat lens and sciatic nerve to a high glucose concentration (50 mM). Seven active compounds among them inhibited sorbitol accumulation by about 50% or more at a concentration of 10(-5)M. These seven compounds were given orally to streptozotocin-induced diabetic rats at a dose of 50 mg/kg/day and were assessed for their abilities to prevent both sorbitol accumulation in two tissues (lens and sciatic nerve) and myo-inositol depletion in the sciatic nerve. 1-[(2,4,5-Trichlorophenyl)sulfonyl]hydantoin, 1-[(2,5-dichlorophenyl)sulfonyl]hydantoin, and 1-[(beta-naphthyl)sulfonyl]hydantoin were found to be the most effective: they inhibited sorbitol accumulation in the sciatic nerve completely and that in the lens by more than 92%. It is conceivable from this study that the three compounds are promising for further investigation targeted to the treatment of diabetic complications.     

Teratogenic and toxicological examination of 2,4,5-trichlorphenoxyacetic acid in developing chick embryos

Practical grade 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), dissolved in dimethylsufoxide (DMSO), was injected into the air space of fertilized chicken eggs prior to incubation. Doses of 2,4,5-T administered were 12.5, 25, 50, 75, 100, and 125 mg/kg to determine herbicide toxicity on the first day of incubation. A similar group was studied on day 5 of incubation with doses of 2,4,5-T at 50, 75, 100 and 250 mg/kg. LD₅₀ was estimated to be 62 mg/kg on day zero and 68 mg/kg on day 5. Additional, embryos were exposed to 2,4,5-T at 50 mg/kg on day zero of gestation and sacrificed after 48 h of incubation. Serial sections were examined for teratological and developmental anomalies. None were found.     

Sequential histopathologic, hematologic, and blood chemistry changes induced in mice by a technical and a purified preparation of 2,4,5-trichlorophenoxyacetic acid.

Maternal mice were given 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on days 6 through 14 of pregnancy in a tetratologic study at the National Center for Toxicological Research. Sick or moribund mice sacrificed after 4-8 doses of 120 mg/kg 2,4,5-T often showed severe myocardial lesions, hypocellularity of the bone marrow, and depletion of lymphocytes in the thymus, spleen, or lymph nodes. Healthy mice sacrificed on day 17, 11 days after treatment began, showed few or no severe lesions. To determine if lesions earlier in gestation contributed significantly to an increase in fetal abnormalities in the healthy 17-day survivors, dihybrid croos F2 pregnant and nonpregnant mice received by gavage 0, 60, or 120 mg/kg 2,4,5-T on days 6 through 14 of pregnancy. One group received a technical preparation containing 97.9 +/- 0.4% 2,4,5-T; another received a purified preparation containing 99 +/- 0.3% 2,4,5-T. Mice were sacrificed when they became moribund and at 6, 24, and 30 hr, as well as at 4, 6, 8, and 11 days after beginning treatment. Almost all mice given 60 mg/kg and many given 120 mg/kg 2,4,5-T appeared normal at sacrifice either early or late in pregnancy and showed little or no pathologic changes. Mice that became ill or moribund often showed severe lesions; few survived 11 days. Severe myocardial lesions were seen in 26 of 70 moribund mice fiven the technical 2,4,5-T and 24 of 33 given the purified preparation of 2,4,5-T. The moribund mice, particularly those given the purified compound, also showed a high incidence of lesions in other organs and marked hematological and blood chemistry changes. These findings indicate that the lesions are primarily due to 2,4,5-T rather than to impurities in the technical preparation; also impaired maternal health is not the primary cause of the increase in fetal abnormalities.     

Developing rat brain monoamine levels following in utero exposure to a mixture of 2,4-dichlorophenoxyacetic and 2,4,5-trichlorophenoxyacetic acids

Pregnant rats were gavaged with a 1:1 mixture of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) at 0 (G0), 50 (G 50) and 100 (G 100) mg/kg per day on gestational days 6-15. Treatment significantly (P less than 0.05) delayed ontogeny of dopamine (DA), but not norepinephrine (NE) levels, in the thalamus-hypothalamus on postnatal day 7; in the pons-medulla on days 7,9 and 15; and in the olfactory lobes on day 9. On day 25, serotonin (5-HT) levels were significantly decreased in the pons-medulla of G 100 rats, whereas 5-hydroxyindoleacetic acid (5-HIAA) levels decreased in the thalamus-hypothalamus and pons-medulla of G 50 and G 100 rats.     

Reproductive and developmental toxicity screening study of 2,4-dinitrophenol in rats

Rats were treated by gavage once daily with 2,4-dinitrophenol (DNP) at 0 (control), 3, 10, or 30 mg/kg bw. Males were dosed for 46 days, beginning 14 days before mating, and females were dosed for 40-47 days, from 14 days before mating to day 3 of lactation. No deaths were observed in males and females of any group. A significant decrease in body weight gain and significant increase in liver weight were found in males and females at 30 mg/kg bw/day. The number of live pups on postnatal days (PNDs) 0 and 4, live birth index, and body weight of live male and female pups on PNDs 0 and 1 were significantly lowered at 30 mg/kg bw/day. External and internal examinations of pups revealed no increased incidence of malformations in DNP-treated groups. On the basis of these findings, we concluded that DNP has general and reproductive/developmental toxicity, but not teratogenicity, under the present conditions. The NOAEL of DNP is considered to be 10 mg/kg bw/day in rats.     

Teratogenic and Embryotoxic Effects of the Herbicides Di- and Trichlorophenoxyacetic Acids (2, 4D and 2, 4, 5-T)

Abstract: Commercial solutions of phenoxyacetic acids were tested for teratogenic effects in NMRI-mice. The Swedish product Hormoslyr 500-T contained only 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) while Hormoslyr 64 was a mixture of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-T (2:1). Subcutaneous injections were given from day 6 through day 14 of pregnancy and the animals were sacrificed on day 18. The number of resorbed embryos, living embryos with gross malformations, as well as internal and skeletal malformations were recorded. It was found that both preparations at the high dosage (110 mg/kg/day) were teratogenic and embryotoxic. At the low dose level (50 mg/kg/day) the 2,4,5-T solution was more harmful than the mixture of 2,4-D and 2,4,5-T. The risks of teratogenicity in human civilian use and the role of dioxins are discussed.     

Ontogeny of swimming behavior and brain catecholamine turnover in rats prenatally exposed to a mixture of 2,4-dichlorophenoxyacetic and 2,4,5-trichlorophenoxyacetic acids

Rats exposed in utero on gestational days 6-15, to nonfetotoxic and grossly nonteratogenic mixtures (50 or 100 mg/kg) of 2,4-D/2,4,5-T as found in Agent Orange (but without significant contamination with 2,3,7,8 tetrachloro-p-dioxin) manifested subtle developmental neurotoxicity. Maturation of swimming behavior was significantly delayed on postnatal day 7 in both treatment groups. The concentration of norepinephrine (NE) in whole brain was significantly increased on postnatal day 15 in both treatment groups, whereas the concentration of dopamine (DA) was increased on postnatal day 15 at 100 mg/kg. The turnover and efflux rate constant of DA in whole brain were significantly reduced whereas the turnover time increased on postnatal day 3. The efflux rate constant for NE decreased and the turnover time increased significantly on postnatal day 15 at 100 mg/kg. These data indicate the value of ontogenic assessment following exposure to small doses, which result in functional alterations in the absence of overt toxic signs.     

In vivo activities of aldose reductase inhibitors having a 1-(arylsulfonyl)hydantoin structure

Two potent aldose reductase inhibitors, 1-[(2,5-dichlorophenyl)sulfonyl]hydantoin (Di-Cl-PSH) and 1-[beta-naphthyl)sulfonyl]hydantoin (beta-NSH), were tested for usefulness in the treatment of diabetic and galactosemic complications in animal experiments. Both drugs were effective for the treatment of diabetic neuropathy characterized by decreased motor nerve conduction velocity, that is, slowing of tail and sciatic-tibial motor nerve conduction velocities in streptozocin-induced diabetic rats was prevented during 3 weeks by intubating Di-Cl-PSH or beta-NSH at 50 mg/kg/day. Lenticular vacuole formation in rats fed a 30% galactose diet was blocked completely for at least 2 weeks by oral administration of Di-Cl-PSH or beta-NSH at both 30 and 100 mg/kg/day, whereas all of the eyes of vehicle-treated rats showed vacuole formation by day 4 on the galactose diet. The ED50 values of Di-Cl-PSH and beta-NSH for inhibition of sorbitol accumulation in the sciatic nerve and lens of streptozocin-induced diabetic rats were also estimated; the values of Di-Cl-PSH and beta-NSH were 1.1 and 3.4 mg/kg/day, respectively, for inhibition in the sciatic nerve and 4.8 and 16.0 mg/kg/day, respectively, for that in the lens. This study indicates that Di-Cl-PSH and beta-NSH have high potential for future clinical use as aldose reductase inhibitors.     

疟疾防治药物的研究——Ⅰ.2,4-二氨基-5-取代氨基嘧啶和2,4-二氨基-6-甲基-5-取代氨基嘧啶衍生物的合成及其抗疟作用

本文报道2,4-二氨基-5-取代氨基嘧啶和2,4-二氨基-6-甲基-5-取代氨基嘧啶衍生物的合成及其抗疟活性的研究。这类化合物的合成是分别以2,4,5-三氨基嘧啶或2,4,5-三氨基-6-甲基嘧啶与相应的取代的苯甲醛缩合成席夫氏碱,然后经还原,亚硝化或甲酰化制得。经鼠疟原虫-斯氏按蚊系统的病因性预防初筛,发现有12个化合物有效,其中2,4-二氨基5-[(3′,4′-二氯代苯亚甲基)-氨基]嘧啶(化合物V₃)和2,4-二氨基-5-[(4′-溴代苄基)-N-亚硝基-氨基]嘧啶(化合物Ⅶ₄)效果最好,口服10 mg/kg共三天,可使小白鼠得到保护,血中未查见原虫。     

Effects of artemisinin, artemether, arteether on the pharmacokinetics of carbamazepine

The effect of artemisinin, artemether and arteether on the pharmacokinetics of carbamazepine in rabbits was studied. In a cross-over study, carbamazepine 40 mg/kg/day orally was given daily for 7 days. On day 7, blood samples were taken at various time intervals between 0 and 24 h. In the artemisinin group, carbamazepine was administered for 7 days as above. On day 8, artemisinin 82 mg/kg followed by 41 mg/kg on the 9th and 10th day along with carbamazepine 40 mg/kg/day was administered and blood samples drawn as above. Artemether 10 mg/kg i.m. was given on day 8 followed by 5 mg/kg i.m. for 2 days. Arteether 10 mg/kg i.m. was given from day 8 for 3 days. Plasma carbamazepine levels were assayed by high-performance liquid chromatography and pharmacokinetic parameters calculated. In all the groups there was an increase in the AUC(0-infinity) when carbamazepine was co-administered with artemisinin, artemether or arteether. The increase in AUC(0-infinity) (22.78 +/- 4.71 to 63.10 +/- 12.29), Cmax (2.76 +/- 0.77 to 7.02 +/- 1.08), Tmax (2.83 +/- 0.17 to 4.16 +/- 0.40) was statistically significant when artemether was given along with carbamazepine (p < 0.05). In the other groups the increase was not significant. These results suggest artemisinin compounds alter the pharmacokinetics of carbamazepine with significant change in the bioavailability. Confirmation of these results in human studies will warrant changes in carbamazepine dose or frequency when either of these antimalarials is co-administered with it.     

Subacute (28-day) toxicity of furfural in Fischer 344 rats: a comparison of the oral and inhalation route.

The subacute oral and inhalation toxicity of furfural vapour was studied in Fischer 344 rats to investigate whether route-to-route extrapolation could be employed to derive the limit value for inhalation exposure from oral toxicity data. Groups of 5 rats per sex were treated by gavage daily for 28 days at dose levels of 6-192 mg/kg bw/day, or exposed by inhalation to concentrations of 20-1280 mg/m3 (6 h/day, 5 days/week) or 160-1280 mg/m3 (3 h/day, 5 days/week) for 28 days. Controls received vehicle (corn oil) or were exposed to clean air. Daily oral treatment with the highest dose of furfural (initially 192 mg/kg bw/day, later reduced to 144 mg/kg bw/day and finally to 120 mg/kg bw/day) resulted in mortality, and in increases in absolute and relative kidney and liver weight in surviving females of this group. Exposure of rats by inhalation for 6 h/day, 5 days/week for 28 days induced mortality at concentrations of 640 mg/m3 and above within 1-8 days. At 640 mg/m3 (3 h/day) and at 320 mg/m3 (3 and 6 h/day) and below, however, exposure was tolerated without serious clinical effects. In contrast, histopathological nasal changes were seen even at the lowest concentration of 20 mg/m3. With increasing exposure concentration, the nasal effects increased in incidence and severity and also expanded from the anterior part to the posterior part, including the olfactory epithelium. It was concluded that the no-observed-adverse-effect level (NOAEL) for oral toxicity was 96 mg/kg bw/day. The NOAEL for systemic inhalation toxicity was comparable, i.e. 92 mg/kg bw/day (corresponding to 320 mg/m3 (6 h/day) or 640 mg/m3 (3 h/day)) assuming 100% absorption. The presence of the histopathological nasal changes at the lowest tested concentration of 20 mg/m3 (corresponding to 6 mg/kg bw/day) proves that for locally acting substances like furfural extrapolation from the oral to the inhalation route is not valid.     

Uterotrophic assay, Hershberger assay, and subacute oral toxicity study of 4,4′-butylidenebis(2-tert-butyl-5-methylphenol) and 3-(dibutylamino)phenol, based on the OECD draft protocols

We performed a uterotrophic assay, the Hershberger assay, and a 28-day repeated-dose toxicity study [enhanced Organization for Economic Co-operation and Development (OECD) test guideline No. 407] of 4,4'-butylidenebis(2-tert-butyl-5-methylphenol) and 3-(dibutylamino)phenol, based on the OECD draft protocols. In the uterotrophic assay of 4,4'-butylidenebis(2-tert-butyl-5-methylphenol), female SD rats were subcutaneously injected with the chemical at doses of 0, 100, 300, and 1,000 mg/kg on each of 3 days from postnatal day 20 to day 22, and no changes were observed. In the Hershberger assay of 4,4'-butylidenebis(2-tert-butyl-5-methylphenol), the test chemical was orally administered to castrated male SD rats at doses of 0, 50, 200, and 1,000 mg/kg/day for ten consecutive days beginning on postnatal day 56, and no changes were observed. When this chemical was orally administered at doses 0, 5, 25, and 125 mg/kg/day for at least 28 days in the subacute oral toxicity study, an increase in thyroid weight was observed in the female rats in the 125 mg/kg group, an increase in serum thyroid-stimulating hormone (TSH) values in the male and female rats in the 125 mg/kg group, and a decrease in serum T3 and T4 values in the male rats in the 125 mg/kg group, and thyroid follicular epithelial cell hypertrophy was observed in some of the female rats in the 125 mg/kg group. These findings were concluded to be the result of endocrine-mediated effects of the chemical on thyroid function. In addition, increased liver weight, abnormal histological findings in the liver, and abnormal biochemical parameters related to liver function were observed in male and/or female rats in 5 mg/kg group and higher dose groups. The no-observed-effect level for 4,4'-butylidenebis(2-tert-butyl-5-methylphenol) was concluded to be <5 mg/kg/day. In the uterotrophic assay of 3-(dibutylamino)phenol, female SD rats were subcutaneously injected with the chemical at doses of 0, 100, 300, and 1,000 mg/kg on each of 3 days from postnatal day 20 to day 22, and no changes were observed. In the Hershberger assay of 3-(dibutylamino)phenol, the test chemical was orally administered at doses of 0, 50, 200, and 400 mg/kg/day to castrated male SD rats for ten consecutive days beginning on postnatal day 56, and no changes were observed. On the other hand, when this test chemical was orally administered at doses 0, 30, 100, and 300 mg/kg/day for at least 28 days in the subacute oral toxicity study, thyroid weight increased in the male rats in the 300 mg/kg group, thyroid follicular epithelial cell hypertrophy was observed in a small number of male rats in the 300 mg/kg group, serum T3-values decreased in the female rats in the 300 mg/kg group, and a tendency for TSH-values to increase was observed in the male and female rats in the 300 mg/kg group. Therefore, 3-(dibutylamino)phenol was also concluded to have slight anti-thyroid acting effects as the endocrine-mediated effects. On the other hand, increased hemosiderin deposition in the spleen, increased spleen weight, hematological abnormalities, and squamous epithelial hyperplasia of the forestomach were detected in male and/or female rats in the 100 and/or 300 mg/kg groups, and thus the no-observed-effect level for 3-(dibutylamino)phenol was concluded to be 30 mg/kg/day.     

Maternal and developmental toxicity in mice by aminophenylnorharman,formed from norharman and aniline

9-(4'-Aminophenyl)-9H-pyrido [3,4-b] indole (aminophenylnorharman, APNH) is a novel mutagenic heterocyclic amine, produced by the reaction of norharman with aniline in the presence of S9 mix. In the present study, the maternal and developmental toxicity of APNH were investigated in ICR mice administered oral doses of 0, 0.625, 1.25, 2.5 or 5 mg/kg/day on gestational days (GD) 6 through 15 or 0, 5, 10, or 20 mg/kg on GD 12. Maternal and foetal parameters were evaluated on day 18 of gestation. Foetuses of dams treated on GD 6-15 were examined for external and skeletal malformations and variations, and foetuses of dams treated on GD 12 were inspected for cleft palate. Maternal death occurred when APNH was administered at 5 mg/kg/day on GD 6-15. No significant decrease in body weight gain during the administration period was observed at doses of 2.5 mg/kg/day or less when applied on GD 6-15. Adverse changes in general condition of dams were observed in the groups treated at doses of 2.5 mg/kg/day and above on GD 6-15, whereas no adverse effects on dams were noted even when APNH was applied at a fairly high dose on GD 12. Intracytoplasmic vacuolation in hepatocytes, necrosis of proximal tubular epithelial cells and desquamation of necrotic epithelial cells in the tubular lumen were observed in dams treated with APNH at 2.5 or 5 mg/kg/day on GD 6-15. Increased preimplantation loss was observed at 5 mg/kg/day and post-implantation loss was observed at 2.5 mg/kg/day and above when applied on GD 6-15, or at 20 mg/kg when applied on GD 12. Foetal body weight was decreased by APNH in a dose-dependent manner. The frequency of external malformations (cleft palate) was significantly increased in the group treated with APNH at 2.5 mg/kg/ day on GD 6-15 compared to the controls. However, there were no foetuses with cleft palate even when APNH was given at 20 mg/kg on GD 12. No significant increases in skeletally malformed foetuses were found in any APNH-treated group. The frequency of lumbar ribs was increased dose dependently. This study demonstrated the developmental toxicity of a mutagenic compound, APNH, in mice at maternally toxic doses, and that cleft palate observed in term foetuses resulted from the adverse effect of APNH on the maternal environment during organogenesis. More detailed studies are warranted to assess the possible risks to pregnant women from exposure to APNH.     

Quaternary heterocyclylamino beta-lactams. V. L-640,876 treatment of induced enterotoxigenic colibacillosis (scours) in calves and piglets

A new semisynthetic cephalosporin antibiotic designated L-640,876, 7-beta-(1-benzylpyridinium-4-yl)amino-3-[( (1-methyl-1H-tetrazol-5-yl)thio] methyl)ceph-3-em-4-carboxylate, was highly active in vitro against 110 enteropathogenic strains of Escherichia coli and Salmonella species of animal origin. The MIC90 was 0.125 microgram/ml for the E. coli strains, 2 micrograms/ml for the S. choleraesuis strains and 4 micrograms/ml for the S. typhimurium strains. In colostrum-fed calves infected with E. coli strain B44, L-640,876 administered by gavage at 30 mg/calf (0.67 mg/kg) twice a day for 3 days, starting at 20-hour post-inoculation, eliminated the diarrhea and reduced the mortality from 82% in the infected, nonmedicated calves to 11% in the infected, medicated calves (P less than 0.05). In colostrum-fed piglets infected with E. coli strain P155, L-640,876 administered by gavage at 12.5 or 20 mg/piglet (10 or 16 mg/kg) twice a day for 3 days, starting at 6-hour post-inoculation, eliminated the diarrhea and reduced the mortality from 79% in the infected, nonmedicated to 25% in the infected, medicated piglets (P less than 0.05). Thus, L-640,876 was highly effective in restoring the calves and piglets to good health by eliminating diarrhea and reducing mortality.     

Antimalarial activities of new guanidylimidazole and guanidylimidazoline derivatives

A series of new guanidylimidazole derivatives was prepared and evaluated in mice and Rhesus monkeys infected with malarial sporozoites. The majority of the new compounds showed poor metabolic stability and weak in vitro activities in three clones of Plasmodium falciparum. Compounds 8a, 8h, 9a, 16a, and 16e cured the mice infected with sporozoites of P. berghei at 160 and 320 mg/kg/day × 3 po. Compounds 8a showed better causal prophylactic activity than primaquine, tafenoquine, and Malarone in the Rhesus test. In the radical curative test, 8a cured one monkey and delayed relapse of another for 74 days at 30 mg/kg/day × 7 by im. By oral dosing, 8a delayed relapse 81 days for one and 32 days for other vs 11-12 days for control monkeys treated with 10 mg/kg of chloroquine by po alone. Compound 8h, which showed superior activity to 8a in mouse test, delayed the relapse of treated monkeys for 21-26 days at 30 mg/kg/day × 7 by oral.     

Evaluation of infrequent dosing regimens with (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]-cytosine (S-HPMPC) on simian varicella infection in monkeys.

(S)-1-[3-Hydroxy-2-(phosphonylmethoxy)propyl]cytosine (S-HPMPC) was able to prevent simian varicella infection in African green monkeys inoculated intratracheally with virus. A dose of 50 mg/S-HPMPC/kg administered intravenously was shown to prevent the development of rash, reduce viremia and protect the monkeys from death. The 50 mg/kg dose was effective when treatments initiated on day 2 post-infection (p.i.) was given as ten daily doses of 5 mg/kg, as 10 mg/kg administered on five days on an alternate-day schedule, as two 25 mg/kg doses given on day 2 and on day 7 p.i., or as a single injection of 50 mg/kg on day 2. The single 50 mg/kg dose was also effective when treatment was delayed until four days p.i., but was ineffective when treatment was delayed until six days p.i. The 50 mg/kg dose was not effective when given orally by gavage. No evidence of toxicity was noted in daily clinical examinations, or in frequent hematology and clinical chemistry tests performed during the clinical evaluation of the infection.     

Inhibition of simian varicella virus infection of monkeys by 1-(2-deoxy-2- fluoro-1-beta-D-arabinofuranosyl)-5-ethyluracil (FEAU) and synergistic effects of combination with human recombinant interferon-beta

1-(2-Deoxy-2-fluoro-1-beta-D-arabinofuranosyl)-5-ethyluracil (FEAU) has been shown to be a highly effective inhibitor of Simian varicella virus infection in African green monkeys. Administration of FEAU by either intravenous injection or gavage at doses as low as 1 mg/kg/day prevented the development of rash and reduced viremia. The effective dose could be further reduced to 0.2 mg/kg/day when administered in combination with a sub-effective dose of human recombinant interferon-beta. No evidence of toxicity was seen in monkeys treated for 10 days with FEAU doses of 10 mg/kg/day when they were monitored by hematology and clinical chemistry tests and by clinical observations.     

Combined repeated dose and reproductive/developmental toxicity screening test of the nitrophenolic herbicide dinoseb, 2-sec-butyl-4,6-dinitrophenol, in rats

In a combined repeated dose toxicity study with reproduction/developmental toxicity screening test, Crj:CD(SD)IGS rats were dosed with dinoseb, 2-sec-butyl-4,6-dinitrophenol, by gavage at 0 (vehicle), 0.78, 2.33, or 7.0 mg/kg bw/day. Six males per group were dosed for a total of 42 days beginning 14 days before mating. Twelve females per group were dosed for a total of 44-48 days beginning 14 days before mating to day 6 of lactation throughout the mating and gestation period. Recovery groups of six males per group and nonpregnant six females per group were dosed for 42 days followed by a 14-day recovery period. No deaths were observed in males of any dose group or in females of the recovery groups. At 7.0 mg/kg bw/day, eight females died and two animals were moribund during late pregnancy, and a significant decrease in body weight gain was found in both sexes. Hematocrit was significantly higher at 0.78 mg/kg bw/day and above in the main group males at the end of administration period. Reduction in extramedullary hematopoiesis in the spleen was significant at 2.33 mg/kg bw/day in the main group females. Sperm analysis revealed a decrease in sperm motility and an increase in the rates of abnormal sperm, abnormal tail, and abnormal head at 7.0 mg/kg bw/day. A number of dams delivered their pups and of dams with live pups at delivery was significantly lowered in the 7.0 mg/kg bw/day group. Based on these findings, the LOAEL for males and NOAEL for females were 0.78 mg/kg bw/day, and the NOAEL for reproductive/developmental toxicity was considered to be 2.33 mg/kg bw/day.     

HPMPC therapy of MCMV-induced retinal disease in the SCID mouse measured by electroretinography,a non-invasive technique

The purpose of these studies was to investigate the use of non-invasive electroretinography for the evaluation of retinal disease and its treatment in an ocular murine cytomegalovirus (MCMV) disease model. While under anesthesia, 10(2.6)plaque forming units (pfu) of salivary gland passaged, Smith strain MCMV was injected in the anterior chamber of 6- to 8-week-old severe combined immunodeficiency (SCID) mice. At various times post-inoculation, bright-flash scotopic electroretinogram, viral titer, and histology were obtained from the injected eye. Antiviral therapy was tested using 0.1 and 5mg/kg/day subcutaneous injections of HPMPC (Cidofovir) once daily for 5 consecutive days. In infected animals, the a- and b-waves of the electroretinographic (ERG) signal were significantly reduced as of 10 days post-inoculation when compared to control animals. Therapy with HPMPC 0.1mg/kg/day subcutaneously (s.c.) once daily for 5 consecutive days was able to delay the decrease in ERG wave amplitude and inhibit viral replication, whereas 5mg/kg/day s.c. significantly protected the ERG, completely inhibited viral replication, and maintained ocular viral titer below the limit of detection for up to 17 days post-infection. The reduction of ERG activity during progression of retinal disease correlated well with reduction of disease pathology. ERG recording represents a valuable non-invasive technique to measure the progression of the retinal disease induced by MCMV and the efficacy of antiviral treatment in the ocular MCMV disease model.     

Adverse effects of diphenyltin dichloride on initiation and maintenance of pregnancy in rats.

The objective of this study was to characterize the adverse effects of diphenyltin dichloride (DPTCl) during early pregnancy. Following successful mating, female rats were given DPTCl by gastric intubation at 0, 4.1, 8.3, 16.5, 24.8 or 33.0 mg/kg on days 0-3 or days 4-7 of pregnancy. Female rats were sacrificed on day 20 of pregnancy and pregnancy outcome was determined. The pregnancy rate was significantly decreased after administration of DPTCl on days 0-3 at 24.8 mg/kg and on days 4-7 at 33.0 mg/kg. The incidence of preimplantation loss was significantly increased after administration on days 0-3 at 16.5 mg/kg and above and on days 4-7 at 33.0 mg/kg. In females having implantations, the numbers of implantations and live fetuses and the incidences of pre- and postimplantation loss in the groups given DPTCl on days 0-3 were comparable to the controls. The incidence of postimplantation loss was significantly increased after administration of DPTCl on days 4-7 at 33.0 mg/kg. A pair-feeding study revealed no evidence of pre- and postimplantation embryolethality induced by food restriction. It could be concluded that DPTCl during early pregnancy causes early embryonic loss and DPTCl has greater effects on reproduction when administered during earlier than later stages of blastogenesis.