Correlation of susceptibility to 6-aminonicotinamide and hydrocortisone-induced cleft palate

Our previous genome-wide Quantitative Trait Locus (QTL) mapping study using mouse A/J by C57BL/6J recombinant inbred (RI) lines suggested several chromosomal regions contain genes influencing susceptibility to phenytoin (PT)-induced cleft lip with or without cleft palate [CL(P)] and 6-aminonicotinamide (6-AN)-induced isolated cleft palate (CP). Importantly, the same chromosomal regions but different RI parental strain alleles were sometimes implicated in susceptibility to these different kinds of orofacial clefting. Here we report the susceptibility to hydrocortisone (HC)-induced CP in these RI lines. We treated pregnant females with HC and studied the incidence of CP in day 17 fetuses. RI lines showed highly correlated responses to HC and 6-AN. The A/J parental line and five RI lines showed very high levels of clefting in response to both of these teratogens. The C57BL/6J parental line and five other RI lines exhibited low incidence of CP for these teratogens. In contrast, there was no significant correlation between incidence of PT-induced CL(P) and HC-induced CP.     

Abnormal head posture associated with induction of cleft palate by methylmercury in C57BL/6J mice

Maternal treatment with methylmercury (MeHg) has been shown to induce a high frequency of cleft palate and produce growth retardation in rat and mouse fetuses, but the relation between these effects is unknown. The objective of this study was to determine if mandibular growth retardation was a factor that contributed to induction of cleft palate in C57BL/6J mice. Two doses of MeHg (10 mg/kg maternal body weight) were given subcutaneously on days 10 and 11 of gestation, and the fetuses were morphometrically studied on days 14, 15, and 18. Full clefts of the secondary palate were present in approximately half of the treated day 15 and 18 fetuses; therefore, the cleft palate (CP) and noncleft palate (NCP) groups were analyzed separately to facilitate identification of morphologic changes associated with the clefting. The results showed that, compared with controls, the day 14 MeHg-treated fetuses had significantly smaller placental weights, but only half of the fetuses had delayed palatal shelf elevation, reduced body weight, and delayed morphological development. However on day 15, the CP and the NCP groups had similar reductions in body weight and placental weight. A striking downward and forward positioning of the head was present in the MeHg-treated fetuses with the CP group more severely affected than the NCP group. Significant differences between the three groups (control, NCP, and CP) were present with mean head-to-body angles of 67 degrees, 60 degrees and 51 degrees, respectively. The absence of normal head lifting resulted in a relative mandibular retrognathia that when combined with a decrease in mandibular length produced alterations in spatial relations that were most severe in the CP fetuses. The results suggest that after exposure to MeHg, palatal closure is affected by altered tongue posture associated with the abnormal head positioning and shortening of the mandible that develop following placental and embryonic growth retardation.     

Teratogenic effects of retinoic acid are modulated in mice lacking expression of epidermal growth factor and transforming growth factor-alpha

BACKGROUND: Epidermal growth factor (EGF) and transforming growth factor-alpha (TGFalpha) regulate cell proliferation and differentiation in the embryo. The induction of cleft palate (CP) by all trans-retinoic acid (RA) was associated with altered expression of TGFalpha, EGF receptor, and binding of EGF. This study uses knockout (KO) mice to examine the roles of EGF and TGFalpha in teratogenic responses of embryos exposed to RA. METHODS: Pregnant wild-type (WT) mice of mixed genetic background, EGF KO, C57BL/6J, and TGFalpha KO mice were given a single oral dose of RA (100 mg/kg, 10 ml/kg) or corn oil on GD 10 at 12 PM, GD 11 at 12 PM or 4 PM, or GD 12 at 8 AM or 12 PM (plug day = GD 0). GD 18 fetuses were examined for external, visceral, and skeletal effects. RESULTS: After exposure to RA on GD 12, the incidence of CP in EGF KO was significantly reduced relative to WT. In TGFalpha KO fetuses, RA exposure on GD 10 increased the incidence of CP versus C57BL/6J. The incidence of skeletal defects in the limbs, vertebrae, sternebrae, and ribs were also affected by lack of expression of EGF or TGFalpha with region-specific amelioration or exacerbation of the effects of RA. In TGFalpha KO fetuses, incidences of forelimb long bone and digit defects increased relative to C57BL/6J. In EGF KO fetuses, relative to WT, the incidence of hindlimb oligodactyly was increased. In EGF KO, but not WT, RA produced short, bent radius, humerus, and ulna. Both TGFalpha and EGF KO mice had increased incidences of dilation of the renal pelvis and this was reduced by RA. CONCLUSIONS: RA exposure produced skeletal and visceral defects in all genotypes; however, EGF or TGFalpha KO influenced the incidence and severity of defects. This study supports a role for EGF and TGFalpha in the response to RA.     

Effects of pulsed magnetic fields on the developing mouse embryo

The influence of a pulsed magnetic field (PMF; sawtooth with 45-μs linear rise time and 5-μs decay time, peak strength of 15 μT, and frequency 20 pps) on the embryogenesis of CBA/S mice was investigated in five experiments based on a total of 707 exposed and 543 unexposed primigravidas. Sham and PMF exposures began on day 1 of gestation (experiments 1 and 2), on day 2 (experiment 3), on day 5 (experiment 4). and on day 7 (experiment 5): all exposures continued until day 19 post conception (p.c.) when they were terminated, at which time the following variables were measured: number of implants; number of placental resorptions; number of living fetuses; number of dead fetuses; number of malformations in living and dead fetuses; and length and body mass of living fetuses. Control dams were sham-exposed concurrently with corresponding. PMF-exposed dams. With the exception of experiment 5, in which exposure to PMF started on day 7 p.c., all groups of exposed mice had significantly more placental resorptions when compared with concurrent controls. The increased resorption rate was not reflected in a reduction in litter size or in the number of litters. A significant increase in malformed fetuses was not seen in any of the exposed groups, or when groups were pooled. Only in experiment 1 was the number of dead fetuses affected by exposure to PMF. The effect of PMF on the implantation rate was not significant. Body mass and length of exposed fetuses were significantly reduced only when the PMF treatment began on day 7 p.c. That PMF-treated mice had significantly more placental resorptions when exposure began on day 5 p.c. or earlier (before implantation), but not when exposure began on day 7 (after implantation), may indicate a causative pre-implantation effect. Because a PMF-induced increase in the number of resorptions has not been observed in other strains of mice, the effect might be strain-related. © 1993 Wiley-Liss, Inc.     

Left cleft lip predominance and genetic similarities of L line and CL/Fr strain mice

Newborn litters of the L line and CL/Fr and A/JFr strains were examined, and sex, frequency and type of cleft lip (left, right or bilateral) were recorded. Embryos and fetuses from crosses between these strains and line were collected on days 13 to 16 of gestation, and frequency and type of cleft lip recorded. Overall cleft frequencies in L X CL/Fr, CL/Fr X L, and CL/Fr X A/JFr crosses (female stated first) were similar, while in A/JFr X L (10.3%) they were significantly lower than in L X A/JFr (23.3%). The data suggested that the same maternal effect genes were present in CL/Fr and the related L line and absent from A/JFr. In the L, CL/Fr, and A/JFr newborns, there was a tendency for males to have higher frequencies of cleft lip and bilateral cleft lip and the latter was significant for L. Left cleft lip frequency was significantly higher than right for L and CL/Fr newborns and in embryos of the CL/Fr X L and L X CL/Fr cross. No significant differences in laterality were found in the A/JFr strain, A/JFr X L, L X A/JFr, and CL/Fr X A/JFr crosses. It was concluded that (1) the embryonic and maternal effect genes for cleft lip are similar or identical in CL/Fr and L; and (2) using data from the literature, there are additional genetic factor(s) increasing left cleft lip occurrence acting in the embryo, which are present in CL/Fr, L, A/HeJ, A/He, and A/St and absent from A/JKt, A/J, A/JFr, and A/WySn.     

Population-Based Study of Birth Prevalence and Factors Associated with Cleft Lip and/or Palate in Taiwan 2002–2009

Background

Facial cleft deformities, including cleft lip with or without cleft palate (CL/P) and cleft palate (CP), are common congenital birth anomalies, especially in Asia. This study aimed to analyze the prevalence of CL/P and CP and to identify associated factors in Taiwan.

Methods

This population-based epidemiological study retrospectively analyzed birth data obtained from the Department of Health in Taiwan for years 2002–2009. Frequency distribution, percentages and related predictors were investigated, and findings were presented by types of cleft deformities. Logistic regression analysis was performed to identify factors associated with cleft deformities.

Results

Overall prevalence of cleft deformities among 1,705,192 births was 0.1% for CL/P and 0.04% for CP over the 8-year study period. Higher prevalence of CL/P or CP was observed with multiple pregnancies, being male for CL/P, being female for CP, gestational age ≤37 weeks and lower birth weight (<1.5 kg). Both CL/P and CP were significantly associated with gestational age <37 weeks and birth weight<1.5 kg (all P <0.0001). CL/P was significantly associated with multiple parities (P = 0.0004–0.002). Male newborns and female newborns were significantly associated with CL/P and CP, respectively (both P<0.0001).

Conclusions

Overall prevalence for congenital cleft deformities in study subjects was 0.1%, in keeping with high rates in Asia. Results suggest the need for awareness and early identification of those at high risk for cleft deformities, including newborns with gestational age <37 weeks, weighing <1.5 kg at birth and women with multiple parities, as a potential strategy to counter long-term adverse effects on speech and language in this population.     

Teratogenic effects of a single oral administration of methylmercuric chloride in mice.

The teratogenic effects of methylmercuric chloride (MMC) given orally as a single dose to pregnant ICR mice on day 10 of gestation were examined. The doses tested were 25, 20, 15 and 10 mg/kg. Controls received distilled water orally. Each group consisted of 20 females. Fetuses were taken on day 18 of gestation for teratological study. The number of resorbed or dead embryos was moderately increased in the 25 mg/kg group. Fetuses from dams given 25, 20 and 15 mg/kg MMC weighed significantly less than those in the control group. Many fetuses with malformations were observed in the treated groups; cleft palate occurred in 100, 58.6 and 28.0% of fetuses from dams given 25, 20 and 15 mg/kg MMC, respectively (statistically significant). Hydronephrosis appeared in 23.8 and 18.5% of fetuses from dams given 25 and 20 mg/kg MMC, respectively (statistically significant). Skeletal variations, incomplete ossification of sternebrae, for example, were also observed in the treated groups. These results indicate that MMC is teratogenic so far as cleft palate is concerned and embryotoxic in ICR mice.     

Experimental study on protection of vitamin B6 on TCDD-induced palatal cleft formation in the mice

BACKGROUND: 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD) can cause a high percentage of cleft palate in fetuses when administered during organogenesis in certain strains of mice including the C57BL/6J. In this study, vitamin B₆ (B₆) was tested for antiteratogenic effects on TCDD-induced cleft palate in fetal mice. METHODS: The pregnant C57BL/6J mice were dosed with 24 µg TCDD/kg and/or 5, 10, 20, and 40 mg B₆/kg body weight on gestation day (GD) 10. The control group mice were dosed with 50 ml sesame oil/kg body weight on GD10. The mice were sacrificed on GD12.5, GD13.5, GD14.5, GD15.5, and GD17.5, respectively. The harvested embryos were examined to detect the incidence of cleft palate and the developing palatal shelves in a different phase were investigated morphologically and histologically among different groups. RESULTS: Total frequency of clefts is 55.56% in the TCDD group and 31.81% (5 mg), 44.44% (10 mg), 40.90% (20 mg), and 32.00% (40 mg) in the TCDD+ B₆ groups. There were no statistically significant differences among the TCDD and TCDD+ B₆ groups (p=0.743>0.05). CONCLUSIONS: It was demonstrated in this study that B6 could not antagonize 2, 3, 7, 8-TCDD-indued cleft palate. Birth Defects Res (Part B) 86:357–361, 2009. © 2009 Wiley-Liss, Inc.     

Etiology and genetic factors in clefts of lip and/or palate reported at children’s hospital,Lahore, Pakistan

The etiology of cleft lip (CL) and/or cleft palate (CP) has been extensively studied in industrialized countries and is suggested to be heterogeneous with increasing evidence that both genetic and environmental factors are operating. To evaluate this assertion in a developing country like Pakistan, a case finding cross-sectional study was completed from 1^st July 2010 to 31^st May 2011 for 100 cases of CL and/or CP referred to the Genetic Clinic of the Children’s Hospital, Lahore, Pakistan. A clinical examination followed by necessary diagnostic work-up was completed for each case. The cause of CL and/or CP was clear in 18% of the children (n = 18). Environmental causes were found in 6 children (four mothers developed hyperthermia during the 2^nd month of gestation, one mother was diabetic, and one mother was a known case of epilepsy and took sodium valproate throughout her pregnancy). Six children were suffering from known genetic malformation syndromes (each with Jarcho-Levin syndrome, Oral-Facial-Digital syndrome type XI, Oral-Duplication syndrome, Kabuki syndrome, Fronto-nasal dysplasia and Nager syndrome). Novel chromosomal aberrations were identified in 2 children. In 82% of the children (n = 82) the cause of oro-facial clefts remained unknown. Impact of gender and consanguinity on the development of CL and/or CP was also studied. Prevalence of CP was significantly more among female children as compared to that in males (P < 0.05). Associated anomalies were present in 18% of the cases, anomalies of the craniofacial region being the most common. These findings were compared with regional and international studies.     

Plasma zinc concentrations of mothers and the risk of oral clefts in their children in Utah

BACKGROUND: The role of maternal zinc nutrition in human oral clefts (OCs) is unclear. We measured plasma zinc concentrations (PZn) of case and control mothers to evaluate the associations between PZn and risk of OCs with and without other malformations. METHODS: Case mothers were ascertained by the Utah Birth Defects Network and control mothers were selected from Utah birth certificates by matching for child gender and delivery month and year. Maternal blood was collected >1 year after the last pregnancy. PZn was available for 410 case mothers who were divided into four subgroups: isolated cleft lip with or without cleft palate (CL/P‐I, n = 231), isolated cleft palate (CP‐I, n = 74), CL/P with other malformations (CLP‐M, n = 42), and CP with other malformations (CP‐M, n = 63). PZn was available for 447 control mothers. The mean age of children at blood sampling was 3.7 years for all cases combined and 4.3 years for controls. RESULTS: Mean PZns of all groups were similar, and low PZn (<11.0 μmol/L) was found in 59% of cases and 62% of controls. Risk of OCs did not vary significantly across PZn quartiles for the four subgroups individually and all OC groups combined. CONCLUSIONS: We previously reported that poor maternal zinc status was a risk factor for OCs in the Philippines, where OC prevalence is high and maternal PZn is low. In Utah, however, no such association was found, suggesting that poor maternal zinc status may become a risk factor only when zinc status is highly compromised. Birth Defects Research (Part A), 2009. © 2008 Wiley‐Liss, Inc.     

Effects of low-frequency magnetic fields on fetal development in rats

We studied effects of alternating magnetic fields on the embryonic and fetal development of rats. Mated females of the Han:Wistar-strain were sham exposed or exposed continuously to a 50-Hz field or to a 20,000 pulse-per-second (pps) sawtooth magnetic field from day 0 to day 20 of pregnancy for 24 h/day until necropsied on day 20. The respective peak-to-peak intensities of the fields were 35.6 μT (sinewave) and 15.0 μT (sawtooth). Each treatment group contained 72 bred females. Control animals were kept under the same conditions without the magnetic field. No adverse effects were seen in the dams. The mean numbers of implantations and living fetuses per litter were statistically significantly increased in the 50-Hz group. There were, however, three total resorptions of litters in dams of the control group, which contributed to the difference in the number of living fetuses. The corrected body-mass gains (gains without uterine content) of dams were similar in all groups. Pregnancy rates, incidences of resorptions. late fetal deaths, and fetal body masses were similar in all groups. The incidence of fetuses with minor skeletal anomalies was statistically significantly increased in both exposed groups. Only one serious malformation (anophthalmia, sawtooth-exposed group) and a few minor visceral malformations were found. In conclusion, the magnetic fields used in this study did not increase the incidence of major malformations or resorptions in Wistar rats. The increased number of skeletal anomalies and implantations we observed indicates, however, that some developmental effects in rats may attend exposure to time-varying magnetic fields. © 1993 Wiley-Liss. Inc.     

Effects of paternal subacute exposure to Tordon 202c on fetal growth and development in CD-1 mice

Male CD-1 mice were exposed to Tordon 202c (a picloram and 2,4-D combination herbicide) in the drinking water at concentrations of 0.21, 0.42, and 0.84% solutions for 60 days prior to mating with untreated females. Subsequently there was no exposure to Tordon 202c during gestation. Fetal weight and crown-rump length were reduced in the highest dosage group. The incidence of malformed fetuses (e.g., ablepharon, cleft palate, and unilateral agenesis of the testes) was increased in the middle dosage group while the incidence of fetuses with variants was increased in the lowest (e.g., an extra pair of ribs) and the highest dosage groups (e.g., incomplete ossification of the skeleton). The frequency of pregnancy failure was increased in the middle dosage group. Indices of paternal toxicity included increased lethality and decreased water consumption in the highest dosage group and increased relative spleen weights in the lowest and middle dosage groups. The results suggest paternally mediated reproductive toxicity.     

Strain differences in teratogenic susceptibility to trypan blue between WM and BDIX rat strains

Female rats of WM (Wistar-Mishima)/Nem strain were mated with WM/Nem (group W) or BDIX/Nem males (group WB), and BDIX/Nem females were mated with BDIX/Nem (group B) or WM/Nem males (group BW). On day 8 of gestation, pregnant females were treated intraperitoneally with 1% aqueous solution of trypan blue at a dose of between 20 and 120 mg/kg of body weight. On day 20 of gestation, fetuses were examined for external, visceral, and skeletal malformations. In group W, fetal mortality increased dose dependently at doses higher than 20 mg/kg, and incidences of external, visceral, and skeletal malformations were significantly higher than control at doses of 30 mg/kg and more. In group B, fetal mortality and the incidence of external malformations were significantly higher than control only in the group treated with 120 mg/kg, and no significant increase of visceral and skeletal malformations was shown. It was confirmed that BDIX strain is much more resistant to trypan blue teratogenicity than WM strain. In group BW, nearly the same teratogenic effects were shown as in group W in terms of fetal mortality and incidence of malformations. However, in group WB, teratogenic effects were not so remarkable as in group BW, suggesting patroclinous effects in teratogenic susceptibility to trypan blue. In group BW, sex differences in teratogenic susceptibility were found; male fetuses were more susceptible to trypan blue than females.     

Susceptible period of nitrous oxide teratogenicity in Sprague-Dawley rats

The susceptible period of nitrous oxide (N2O) teratogenicity was studied in 170 Sprague-Dawley rats. Seven groups of 20 timed-pregnant rats were exposed to 60% N2O for 24 hours on each of days 6-12 of gestation; a control group of 30 timed-pregnant rats was exposed to air on day 9. On day 20 of gestation, dams were killed and reproductive indices were determined; their fetuses were subsequently examined for external, skeletal, and visceral abnormalities. There were no differences among the groups in the number of implantations and live fetuses, mean fetal weight, and sex ratio. The incidence of fetal wastage was higher than control in N2O-treated groups exposed on days 8 and 11 of gestation. Skeletal malformations of the ribs and vertebrae were increased following exposure on day 9 of gestation. However, the specific minor anomaly, cervical rib, was increased only following exposure on day 8 of gestation. The incidences of right-sided aortic arch and left-sided umbilical artery, abnormalities indicative of altered laterality, were increased following exposure on day 8 of gestation. Nitrous oxide administration during organogenesis causes several reproductive defects by mechanisms which remain to be determined.     

Impacts of protein supplementation during late gestation of beef cows on maternal skeletal muscle and liver tissues metabolism

Since nutritional requirements are increased at the end of gestation to meet the demands of the pregnant uterus, pregnant beef cows are susceptible to mobilization of body reserves (mainly fat and amino acids (AAs)) and to alter the metabolism of nutrients in the liver and muscle to support such demands. The objective of this study was to evaluate the effect of CP supplementation on maternal nutrient metabolism in the late gestation of beef cows grazing a low-quality pasture. Forty-three pregnant Nellore cows gestating male fetuses (average age = 6 years; average weight = 544 kg) at 193 ± 30 (mean ± SD) days (d) of gestation were divided into eight groups (experimental units, with four to five cows each). Treatments were (1) control (CON, n = 4): pasture-based (PB) diet without CP supplementation and (2) supplemented (SUP, n = 4): PB diet daily supplemented with 2 g/kg of BW of a 43.5% CP supplement. Liver and skeletal muscle biopsies were performed at 265 days of gestation and samples were collected for mRNA expression. On day 280 of gestation, blood samples were collected to assess plasma levels of AA. The CON-fed cows tended to have greater (P = 0.057) total circulating AA than SUP-fed cows. The circulating glycogenic AA was greater (P = 0.035) in CON than in SUP cows. CON cows was greater for histidine (P = 0.015), methionine (P = 0.007) and alanine (P = 0.036) than SUP cows. The CON- and SUP-fed showed no differences for gluconeogenesis, fatty acid transport and signaling axis markers in the liver. The mRNA expression of markers for skeletal muscle synthesis, p7056k (P = 0.060) and GSK3B (P = 0.096), tended to be greater in cows from CON than SUP group. No differences were found for mRNA expression of markers for skeletal muscle degradation. We conclude that CP supplementation to CP-restricted late-pregnant beef cows reduces the maternal tissue mobilization and changes the profile of plasma circulating AA and the mRNA expression of markers for the synthesis of skeletal muscle tissue.     

Effects of ciprofloxacin on fetal rat liver during pregnancy and protective effects of quercetin

Urinary tract infections are common in pregnant women and ciprofloxacin frequently is used as a broad spectrum antibiotic. It has been suggested that ciprofloxacin causes liver damage in fetuses. Quercetin is a flavonoid with antioxidant properties. We investigated the efficacy of quercetin treatment for preventing fetal liver damage caused by ciprofloxacin. Pregnant rats were divided into four groups: untreated control group (C), 20 mg/kg quercetin for 21 days group (Q), 20 mg/kg twice/day ciprofloxacin for 10 days group (CP), and 20 mg/kg, ciprofloxacin + quercetin for 21 days group (CP + Q). Fetal livers were removed on day 21 of gestation to measure antioxidants and for histological observation. Malondialdehyde (MDA) and glutathione (GSH) levels, and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities were measured in tissue samples. GSH-Px, SOD and CAT activities were significantly lower in the CP group compared to group C. A significant increase in MDA was observed in the CP group compared to group C. There was no significant difference in GSH levels in any group. MDA levels were lower and CAT, SOD and GSH-Px enzyme activities were higher in the CP + Q group compared to group CP. Liver samples of the CP group exhibited central vein dilation, portal vein congestion, pyknotic nuclei and cytoplasmic vacuolization in some hepatocytes. Histological changes were less prominent in the rats treated with quercetin. Use of ciprofloxacin during pregnancy caused oxidative damage in fetal liver tissue. Oxidative stress was ameliorated by quercetin. Quercetin supports the antioxidant defense mechanism and it is beneficial for treating fetal liver damage caused by ciprofloxacin.     

Teratogenicity of zinc deficiency in the rat: study of the fetal skeleton

Zinc deficiency (ZD) is teratogenic in rats, and fetal skeletal defects are prominent. This study identifies fetal skeletal malformations that affect calcified and non-calcified bone tissue as a result of gestational zinc deficiency in rats, and it assesses the effect of maternal ZD in fetal bone calcification. Pregnant Sprague-Dawley rats (180-250 g) were fed 1) a control diet (76.4 micrograms Zn/g diet) ad libitum (group C), 2) a zinc-deficient diet (0 microgram/g) ad libitum (group ZD), or 3) the control diet pair-fed to the ZD rats (group PF). On day 21 of gestation, laparotomies were performed. Fetuses were weighed, examined for external malformations, and stained in toto with a double-staining technique for the study of skeletal malformations. Maternal and fetal tissues were used for Zn, Mg, Ca, and P determinations. Gross external malformations were present in 97% of the ZD fetuses. No external malformations were found in fetuses from groups C and PF. Ninety-one percent of cleared ZD fetuses had multiple skeletal malformations, whereas only 3% of the fetuses of group PF had skeletal defects; no skeletal malformations were found in fetuses from group C. Some of the skeletal malformations described in the ZD fetuses, mainly affecting non-calcified bone, were not mentioned in previous reports, thus stressing the importance of using double-staining techniques. Examination of stained fetuses and counting of ossification centers revealed important calcification defects in ZD fetuses. These effects were confirmed by lower Ca and P concentrations in fetal bone with alteration of the Ca:P ratio.     

Developmental toxicity of pentostatin (2'-deoxycoformycin) in rats and rabbits

The developmental toxicity of the potent adenosine deaminase (ADA) inhibitor, pentostatin (2'-deoxycoformycin), was investigated in pregnant rats and rabbits administered daily iv doses during organogenesis. Rats received 0, 0.01, 0.10, or 0.75 mg/kg on gestation days 6-15 and rabbits received 0, 0.005, 0.01, or 0.02 mg/kg on gestation days 6-18 and maternal and fetal parameters were evaluated on gestation day 21 (rats) or 30 (rabbits). Live fetuses were examined for external, visceral, and skeletal malformations and variations. In rats, maternal body weight gain and food consumption were significantly suppressed at doses of 0.10 and 0.75 mg/kg during the treatment period but returned to control levels during posttreatment. Increased postimplantation loss and decreased numbers of live fetuses, litter size, and fetal body weight were observed at 0.75 mg/kg. A statistically significant increase in the incidence of vertebral malformations occurred at 0.75 mg/kg. The incidence of certain skeletal variations (extra presacral vertebrae, extra ribs, hypoplastic vertebrae) was also increased at 0.75 mg/kg. Ossification of cervical centra was reduced at 0.75 mg/kg compared with controls. In rabbits, marked maternal toxicity (death, body weight loss, and decreased food consumption) and reproductive toxicity (abortion and premature delivery) occurred in all pentostatin-treated groups. However, there were no significant effects on number of live fetuses, pre- or postimplantation loss, litter size, or fetal body weights in the animals with live litters. There was also no apparent increase in the incidence of malformations or variations in the live fetuses of pentostatin-treated rabbits. Thus, these studies demonstrate developmental toxicity of pentostatin in rats and rabbits, and teratogenicity in rats, at maternally toxic doses.     

Effects of low-frequency magnetic fields on fetal development in CBA/Ca mice

Effects of alternating magnetic fields (MFs) on the embryonic and fetal development in CBA/Ca mice were studied. Mated females were exposed continuously to a sinusoidal 50 Hz (13 μT or 0.13 mT root mean square) or a sawtooth 20 kHz (15 μT peak-to-peak) MF from day 0 to day 18 of pregnancy for 24 h/day until necropsied on day 18. Control animals were kept under the same conditions without the MF. MFs did not cause maternal toxicity. No adverse effects were seen in maternal hematology and the frequency of micronuclei in maternal bone marrow erythrocytes did not change. The MFs did not increase the number of resorptions or fetuses with major or minor malformations in any exposure group. The mean number of implantations and living fetuses per litter were similar in all groups. The corrected weight gain (weight gain without uterine content) of dams, pregnancy rates, incidences of resorptions and late fetal deaths, and fetal body weights were similar in all groups. There was, however, a statistically significant increase in the incidence of fetuses with at least three skeletal variations in all groups exposed to MFs. In conclusion, the 50 Hz or 20 kHz MFs did not increase incidences of malformations or resorptions in CBA/Ca mice, but increased skeletal variations consistently in all exposure groups. Bioelectromagnetics 19:477–485, 1998. © 1998 Wiley-Liss, Inc.     

Preventive effect of piperonyl butoxide on cyclophosphamide-induced teratogenesis in rats

BACKGROUND: Cyclophosphamide induces fetal defects through metabolic activation by cytochrome P-450 monooxygenases (CYP). The effects of piperonyl butoxide (PBO), a CYP inhibitor, on the fetal development and external, visceral, and skeletal abnormalities induced by cyclophosphamide were investigated in rats. METHODS: Pregnant rats were daily administered PBO (400 mg/kg) by gavage for 7 days (the 6th to 12th day of gestation), and intraperitoneally administered with cyclophosphamide (12 mg/kg) 4 h after the final treatment. On the 20th day of gestation, maternal and fetal abnormalities were determined by Cesarean section. RESULTS: Cyclophosphamide reduced fetal body weights by 30–40% without increasing resorption or death. In addition, it induced malformations in live fetuses: 100, 98, and 98.2% of the external (head and limb defects), visceral (cerebroventricular dilatation, cleft palate, and renal pelvic/ureteric dilatation), and skeletal (acrania, vertebral/costal malformations, and delayed ossification) abnormalities, respectively. The pre-treatment of PBO greatly decreased mRNA expression and activity of hepatic CYP2B, which metabolizes cyclophosphamide into teratogenic acrolein and cytotoxic phosphoramide mustard. Moreover, PBO remarkably attenuated cyclophosphamide-induced body weight loss and abnormalities of fetuses; score 3.57 versus 1.87 for exencephaly, 75.5% versus 42.5% for limb defects, 65.3% versus 22% for cerebroventricular dilatation, 59.2% versus 5.1% for cleft palate, score 1.28 versus 0.93 for renal pelvic/ureteric dilatation, 71.9–82.5% versus 23–45.9% for vertebral/costal malformations, and 84.2% versus 57.4% for delayed ossification in cyclophosphamide alone and PBO co-administration groups. CONCLUSIONS: These results suggest that repeated treatment with PBO may improve cyclophosphamide-induced body weight loss and malformations of fetuses by down-regulating CYP2B. Birth Defects Res (Part B) 86:402–408, 2009. © 2009 Wiley-Liss, Inc.