Biomedical subjects

M S Tassinari

Publications and source records attributed to M S Tassinari.

At least 19 recordsLinked to original sources

PubMed2004

Reproductive toxicity assessment of lasofoxifene, a selective estrogen receptor modulator (SERM), in female rats.

BACKGROUND: Lasofoxifene is a nonsteroidal selective estrogen receptor modulator (SERM). With high affinity to the alpha and beta human estrogen receptors and greater potency than other SERMs, lasofoxifene is potentially a superior treatment for postmenopausal osteoporosis. In light of the known effects of estrogen-modulating compounds on female reproductive indices, two studies were conducted to evaluate the effects of lasofoxifene on female rat cyclicity, reproduction, and parturition. METHODS: One study evaluated effects of lasofoxifene on estrous cyclicity, and the second study assessed effects on implantation and parturition. In the cyclicity study, lasofoxifene was administered to female rats at doses of 0.1, 0.3, and 1.0 mg/kg/day for 14 consecutive days. After treatment, there was a 3-week reversibility phase followed by a mating phase. In the implantation study, lasofoxifene was administered to pregnant female rats at doses of 0.01, 0.03, and 0.1 mg/kg/day for 7 consecutive days (gestation day [GD] 0-6). Some animals were euthanized on GD 21, and the remainder of the group was allowed to deliver the F1 generation. Several developmental indices were evaluated in the F1 pups through post-natal day (PND) 21. RESULTS: In the cyclicity study, all lasofoxifene-treated females were anestrous by Study Day 7 (1.0 mg/kg) or 9 (0.3 and 0.1 mg/kg). The reversibility phase resulted in restoration of normal estrous cycles by the end of 1 (0.1 mg/kg) or 2 weeks (0.3 and 1.0 mg/kg). During the mating phase, no adverse effects occurred in pregnancy success or reproductive parameters. In the implantation study, all doses of lasofoxifene increased pre- and post-implantation losses, increased gestation length, and reduced litter size. None of the developmental parameters measured on the F1 generation was adversely affected. CONCLUSION: Lasofoxifene reversibly altered the estrous cycle and inhibited implantation, consistent with what would be expected from a member of the SERM class.

Animals↗

PubMed2003

Comparison of the developmental toxicity of aspirin in rabbits when administered throughout organogenesis or during sensitive windows of development.

BACKGROUND: A review of the nonsteroidal anti-inflammatory drug (NSAID) literature suggested occurrences of low-level incidences of cardiovascular and midline defects in rabbit fetuses exposed in utero. Aspirin (acetylsalicylic acid, ASA) is a widely used NSAID that irreversibly inhibits cyclooxygenases (COXs) 1 and 2. ASA has been studied extensively in rats and has consistently increased low-incidence cardiovascular malformations and defects in midline closure. The objectives of the current study were to comprehensively define the developmental toxicology profile of ASA in rabbits by using a dosing paradigm encompassing the period of organogenesis and to test the hypothesis that maternal gastrointestinal toxicity after repeated dose administrations hampers the detection of low-incidence malformations with ASA in rabbits by limiting ASA administration to sensitive windows for cardiovascular development and midline closure. METHODS: ASA was administered to pregnant New Zealand White rabbits from gestation days (GDs) 7 to 19 at dose levels of 125, 250, and 350 mg/kg per day and as single doses of 500, 750, or 1000 mg/kg on GD 9, 10, or 11. Cesarean sections were performed on GD 29, and the fetuses were examined for external, visceral and skeletal development. RESULTS: In the repeated dose study, maternal toxicity was exhibited in the 250- and 350-mg/kg per day groups by mortality and decreased food consumption and body weight gain. In the single dose studies, maternal toxicity was exhibited at all doses by reductions in body weight gain and food consumption for 3 days after treatment. Fetal body weight was significantly reduced in the repeated dose study at 350 mg/kg per day. Fetal weights were not affected by single doses of ASA on GD 9, 10, or 11. There were no treatment-related external, visceral or skeletal malformations associated with ASA administration throughout organogenesis or with single doses administered during critical developmental windows. CONCLUSION: These findings supported previous work demonstrating that ASA is not teratogenic in rabbits, as opposed to rats, even when large doses are administered on single days during specific windows of development.

Abnormalities, Drug-Induced↗

PubMed1994

Differential effects of warfarin on mRNA levels of developmentally regulated vitamin K dependent proteins, osteocalcin, and matrix GLA protein in vitro.

The role of the vitamin K dependent proteins, osteocalcin which is bone specific and matrix Gla protein (MGP) found in many tissues, has been studied by inhibition of synthesis of their characteristic amino acid, gamma-carboxyglutamic acid (Gla) with the anticoagulant sodium warfarin. The effect of sodium warfarin on expression of these proteins, and other phenotypic markers of bone and cartilage during cellular differentiation and development of tissue extracellular matrix, was examined in several model systems. Parameters assayed include cell growth (reflected by histone gene expression) and collagen types I and II, osteopontin, alkaline phosphatase, and mineralization. Studies were carried out in calvarial bone organ cultures, normal diploid rat osteoblast and chondrocyte cultures, and rat osteosarcoma cell lines ROS 17/2.8 and 25/1. In normal diploid cells, warfarin consistently stimulated cell proliferation (twofold). In osteoblast cultures, MGP mRNA levels were generally increased (three to tenfold). Notably, MGP mRNA levels were not affected in chondrocyte cultures, either with chronic or acute warfarin treatments. Osteocalcin mRNA levels and synthesis were decreased up to 50% in ROS 17/2.8 cells and in chronically treated (1 and 5 micrograms/ml sodium warfarin) rat osteoblast cultures after 22 days. Early stages of osteoblast phenotype development from the proliferation period to initial tissue formation (nodules) appeared unaffected; while after day 14, further growth and mineralization of the nodule areas were significantly decreased in warfarin-treated cultures. In summary, warfarin has opposing effects on the expression of two vitamin K dependent proteins, MGP and osteocalcin, in osteoblast cultures and MGP is regulated differently between cartilage and bone as reflected by cellular mRNA levels. Additionally, warfarin effects expression of nonvitamin K dependent proteins which may reflect the influence of warfarin on endoplasmic reticulum associated enzymes.

Animals↗

PubMed1993

Inhibition of induced endochondral bone development in caffeine-treated rats.

We have addressed questions raised by the observation in fetal rats of delayed ossification induced by caffeine at maternal doses above 80 mg/kg body weight per day. The effect of caffeine on endochondral bone development and mineralization has been studied in an experimental model system of bone formation which involves implantation of demineralized bone particles (DBP) in subcutaneous pockets of young growing rats. Caffeine's effects on cellular events associated with endochondral ossification were examined directly by quantitating cellular mRNA levels of chondrocyte and osteoblast growth and differentiation markers in DBP implants from caffeine-treated rats harvested at specific stages of development (day 7 through day 15). Oral caffeine administration to rats implanted with DBP resulted in a dose dependent inhibition of the formation of cartilage tissue in the implants. Histologic examination of the implants revealed a decrease in the number of cells which were transformed to chondrocytes compared to control implants. Those cartilaginous areas that did form, however, proceeded through the normal sequelae of calcified cartilage and bone formation. At the 100 mg/kg dose, cellular levels of mRNA for histone, collagen type II, and TGF beta were all reduced by greater than 40% of control implants consistent with the histological findings. Alkaline phosphatase activity in the implants and mRNA levels for proteins reflecting the hypertrophic chondrocyte and bone phenotype, collagen type I and osteocalcin were markedly decreased compared to controls. Lower doses of 50 and 12.5 mg/kg caffeine also resulted in decreased cellular proliferation and transformation to cartilage histologically and reflected by significant inhibition of type II collagen mRNA levels (day 7). The effects of caffeine on gene expression observed in vivo during the period of bone formation (day 11 to day 15) in the DBP model were similar to the inhibited expression of H4, alkaline phosphatase, osteocalcin, and osteopontin found in fetal rat calvarial derived osteoblast cultures following 24 hour exposure of the cultures to 0.4 mM caffeine. Thus the observed delayed mineralization in the fetal skeleton associated with caffeine appears to be related to an inhibition of endochondral bone formation at the early stages of proliferation of undifferentiated mesenchymal cells to cartilage specific cells as well as at later stages of bone formation.

Administration, Oral↗

PubMed1992

Downregulation of histone H4 gene transcription during postnatal development in transgenic mice and at the onset of differentiation in transgenically derived calvarial osteoblast cultures.

In vivo regulation of cell cycle dependent human histone gene expression was examined in transgenic mice using a fusion construct containing 6.5 kB of a human H4 promoter linked to the chloramphenicol acetyltransferase (CAT) reporter gene. Transcriptional control of histone gene expression, as a function of proliferative activity, was determined. We established the relationship between DNA replication dependent H4 mRNA levels (Northern blot analysis) and H4 promoter activity (CAT assay) during postnatal development in a broad spectrum of tissues. In most tissues sampled in adult animals, the cellular representation of H4 gene transcripts declined in parallel with promoter activity. This result is consistent with transcriptional control of H4 gene expression at the cessation of proliferation. Interestingly, while H4 mRNA was detectable at very low levels post-proliferatively in brain, promoter activity persisted in adult brain, where most of the cells are terminally differentiated. This dissociation between histone gene promoter activity and histone mRNA accumulation points to the possibility of post-transcriptional regulation of histone gene expression in brain. Cultures of osteoblasts were prepared from calvaria of transgenic mice carrying the H4 promoter/CAT reporter construct. In contrast to the brain, in these bone-derived cells, we established by immunohistochemistry that the transition to the quiescent, differentiated state is associated with a transcriptionally mediated downregulation of histone gene expression at the single cell level.

Aging↗

PubMed1991

Effect of caffeine on parameters of osteoblast growth and differentiation of a mineralized extracellular matrix in vitro.

The effects of caffeine exposure on bone formation were examined using a chick osteoblast culture system. Secondary cultures of normal diploid osteoblasts were exposed to chronic doses of 0, 0.1, 0.2, or 0.4 mM caffeine beginning on day 0 through day 28. Neither the rate of cell proliferation nor cell number, as measured by total DNA, was decreased for any of the doses examined. In contrast, osteocalcin levels, alkaline phosphatase activity, and total calcium levels showed a dose-related decrease in cultures treated with caffeine. These parameters were significantly decreased at the highest dose of 0.4 mM. The reduction in total protein levels ranged from 29 to 66% of control values and was independent of dose. In contrast, total collagen levels were more affected by the dose of caffeine used. Inhibition of collagen levels was most apparent on days 17 and 21, time points during the period of active formation of the matrix immediately preceding the deposition of mineral. By day 28 collagen levels in cultures exposed to the lower doses of caffeine had returned to control levels, and only the cultures exposed to the highest dose (0.4 mM) remained significantly inhibited with respect to both collagen and mineral. Histochemically, alkaline phosphatase and mineral staining of day 28 cultures mirrored the biochemical events with the 0.4 mM caffeine exposure. The results indicate that one of the effects of caffeine on bone development is to inhibit the formation of a competent extracellular matrix during the osteoblast differentiation sequence, which results in the inhibition of mineralization analogous to the delayed ossification observed in fetal animals after prenatal caffeine exposure.

Alkaline Phosphatase↗

PubMed1991

Developmental expression and hormonal regulation of the rat matrix Gla protein (MGP) gene in chondrogenesis and osteogenesis.

Matrix Gla protein (MGP), a vitamin K dependent protein, has recently been identified in many tissues. However, it is accumulated only in bone and cartilage suggesting that the expression of MGP may be related to the development and/or maintenance of the phenotypic properties of these tissues. We systematically evaluated MGP mRNA expression as a function of bone and cartilage development and also as regulated by vitamin D during growth and cellular differentiation. Three experimental models of cartilage and bone development were employed: an in vivo model for endochondral bone formation, as well as in primary cells of normal diploid rat chondrocyte and osteoblast cultures. MGP was expressed at the highest level during cartilage formation and calcification in vivo during endochondral bone formation. In chondrocyte cultures, MGP mRNA was present throughout the culture period but increased only after 3 weeks concomitantly with type I collagen mRNA. In osteoblast cultures, MGP mRNA was expressed during the proliferative period and exhibited increased expression during the period of matrix development. In contrast to osteocalcin (bone Gla protein), this increase was not dependent on mineralization but was related to the extent of differentiation associated with and potentially induced by extracellular matrix formation. During the proliferative period, type I collagen mRNA peaked and thereafter declined, while type I collagen protein steadily accumulated in the extracellular matrix. Constant MGP levels were maintained in the mineralization period of osteoblast differentiation in vitro which is consistent with the constant levels found during the osteogenic period of the in vivo system. MGP mRNA levels in both osteoblasts and chondrocytes in culture were significantly elevated by 1,25-(OH)2D3 (10(-8) M, 48 h) throughout the time course of cellular growth and differentiation. Interestingly, when MGP mRNA transcripts from vitamin D treated and untreated chondrocytes and osteoblasts were analyzed by high resolution Northern blot analysis, we observed two distinct species of MGP mRNA in the vitamin D treated chondrocyte cultures while all other cultures examined exhibited only a single MGP mRNA transcript. Primer extension analysis indicated a single transcription start site in both osteoblasts and chondrocytes with or without vitamin D treatment, suggesting that the lower molecular weight MGP message in vitamin D treated chondrocytes may be related to a modification in post-transcriptional processing. In conclusion, these results show that the selective accumulation of MGP in bone and cartilage tissues in vitro may be related to the development and/or maintenance of a collagenous matrix as reflected by increases in MGP mRNA during these periods.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1991

No change in spontaneous behavior of rats after acute oral doses of aspartame, phenylalanine, and tyrosine.

Spontaneous behavior subsequent to acute oral administration of high doses of aspartame, phenylalanine, or tyrosine was analyzed using a computer pattern recognition system. Sprague-Dawley male rats (250-300 g) were dosed orally with aspartame (500 or 1000 mg/kg), phenylalanine (281 or 562 mg/kg), or tyrosine (309 or 618 mg/kg), and their behavior was analyzed 1 hr after dosing. The computer pattern recognition system recorded and classified 13 different behavioral acts performed by the animals during the first 15-min exploration of a novel environment. Three measures that provide independent information concerning motor output from the central nervous system were taken: the number of behavioral initiations, total time, and time structure. These results were compared with the effects induced by d-amphetamine. Plasma concentrations of phenylalanine and tyrosine were determined from blood samples taken immediately after behavioral examination. Data analysis revealed that these doses of aspartame, phenylalanine, and tyrosine did not induce any significant changes in spontaneous behavior. Unlike low doses of amphetamine and despite high plasma concentrations of phenylalanine and tyrosine, no behavioral alteration was detected by the computer pattern recognition system. Absence of behavioral changes in this study using an objective analysis of behavior raises questions concerning the relationship between amino acid precursor loading and purported anecdotal changes in behavior following aspartame administration.

Animals↗

PubMed1990

An animal model to study toxicity of central nervous system therapy for childhood acute lymphoblastic leukemia: effects on growth and craniofacial proportion.

Many long term survivors of childhood acute lymphoblastic leukemia have short stature, as well as craniofacial and dental abnormalities, as side effects of central nervous system prophylactic therapy. An animal model is presented to assess these adverse effects on growth. Cranial irradiation (1000 cGy) with and without prednisolone (18 mg/kg i.p.) and methotrexate (2 mg/kg i.p.) was administered to 17- and 18-day-old Sprague-Dawley male and female rats. Animals were weighed 3 times/week. Final body weight and body length were measured at 150 days of age. Femur length and craniofacial dimensions were measured directly from the bones, using calipers. For all exposed groups there was a permanent suppression of weight gain with no catch-up growth or normal adolescent growth spurt. Body length was reduced for all treated groups, as were the ratios of body weight to body length and cranial length to body length. Animals subjected to cranial irradiation exhibited microcephaly, whereas those who received a combination of radiation and chemotherapy demonstrated altered craniofacial proportions in addition to microcephaly. Changes in growth patterns and skeletal proportions exhibited sexually dimorphic characteristics. The results indicate that cranial irradiation is a major factor in the growth failure in exposed rats, but chemotherapeutic agents contribute significantly to the outcome of growth and craniofacial dimensions.

Animals↗

PubMed1990

An animal model to study toxicity of central nervous system therapy for childhood acute lymphoblastic leukemia: effects on behavior.

Central nervous system prophylactic therapy used in the treatment of acute lymphoblastic leukemia can reduce intelligence quotient scores and impair memory and attention in children. Cranial irradiation, intrathecal methotrexate, and steroids are commonly utilized in acute lymphoblastic leukemia therapy. How they induce neurotoxicity is unknown. This study employs an animal model to explore the induction of neurotoxicity. Male and female Sprague-Dawley rats at 17 and 18 days of age were administered 18 mg/kg prednisolone, 2 mg/kg methotrexate, and 1000 cGy cranial irradiation. Another 18-day-old group was administered 1000 cGy cranial irradiation but no drugs. Matching controls received saline and/or a sham exposure to radiation. All animals at 6 weeks and 4 months of age were tested for alterations in spontaneous behavior. A computer pattern recognition system automatically recorded and classified individual behavioral acts displayed during exploration of a novel environment. Measures of behavioral initiations, total time, and time structure were used to compare treated and control animals. A permanent sex-specific change in the time structure of behavior was induced by the prednisolone, methotrexate, and radiation treatment but not by radiation alone. Unlike hyperactivity, the effect consisted of abnormal clustering and dispersion of acts in a pattern indicative of disrupted development of sexually dimorphic behavior. This study demonstrates the feasibility of an animal model delineating the agent/agents responsible for the neurotoxicity of central nervous system prophylactic therapy.

Animals↗

PubMed1990

Effect of sodium warfarin on vitamin K-dependent proteins and skeletal development in the rat fetus.

Sodium warfarin was administered daily to Sprague-Dawley rats from gestational day 8 to day 22 to examine the effects of this compound on the developing fetal skeleton and on the vitamin K-dependent bone and cartilage proteins. At a dose of 175 micrograms/kg of sodium warfarin there was a 43% mortality rate among the dams. Maternal prothrombin times and serum osteocalcin levels were slightly elevated but not significantly. In the surviving litters, fetal bone osteocalcin and gamma-carboxyglutamic acid were significantly reduced (50 and 57%, respectively, on gestational day 22) when compared to age- and/or weight-matched control pups. The high correlation of osteocalcin content in long bone (R = 0.64) and calvariae (R = 0.77) to fetal body weight observed in control fetuses was not seen in the warfarin-exposed pups. Examination of alizarin-stained warfarin-exposed fetal skeletons for ossification centers showed no difference from controls. However, analysis of the tibial growth showed several changes compared to control that included (1) widened hypertrophic zones, (2) increased calcification of the hypertrophic zones, and (3) disorganization of the hypertrophic cells. These results suggest that the growth plate abnormalities seen with prenatal warfarin exposure relate to the inhibition of the vitamin K-dependent proteins of the skeletal system.

Animals↗

PubMed1990

Gene expression during endochondral bone development: evidence for coordinate expression of transforming growth factor beta 1 and collagen type I.

Subcutaneous implantation of demineralized bone particles (DBP) into rats induces the formation of a bone ossicle by a tightly controlled sequence of chondro- and osteo-inductive events which are directly comparable to those which occur in normal endochondral bone development. Although the morphological and biochemical sequence associated with endochondral bone formation in this model has been well characterized, to date little information is available as to the gene regulation by which these events occur. To examine the expression of genes in this system, RNA was isolated from implants every 2 days over a time course spanning 3 to 19 days after implantation of DBP into rats. Cellular levels of mRNA transcripts of cell-growth-regulated and tissue-specific genes were examined by slot blot analysis and compared to the morphological changes occurring during formation of the ossicle. Analysis of the mRNA levels of histone H4 and c-myc, markers of proliferative activity, revealed several periods of actively proliferating cells, corresponding to 1) production of fibroprogenitor cells (day 3), 2) onset of bone formation (day 9), and 3) formation of bone marrow (day 19). The mRNA levels of collagen type II, a phenotypic marker of cartilage, peaked between days 7 and 9 post-implantation, corresponding to the appearance of chondrocytes in the implant, and rapidly declined on day 11 (to 5% of maximum value) when bone formation was observed. The peak mRNA levels of collagen type I, found in fibroblasts and osteoblasts, occurred first with the onset of bone formation (days 7-10) and again during formation of bone marrow (day 19). This study has demonstrated that the temporal patterns of mRNA expression of cartilage type II and bone type I collagens coincide with the morphological sequence in this model of endochondral bone formation. Further, the mRNA levels of transforming growth factor beta 1 (TGF beta) were compared to those of collagen types I and II; a direct temporal correlation of TGF beta mRNA levels with that of collagen type I was found throughout the developmental time course. This observation of a tightly coupled relationship between TGF beta and type I collagen mRNA levels is consistent with a functional role for TGF beta in extracellular matrix production during in vivo bone formation.

Animals↗

PubMed1990

Factors that promote progressive development of the osteoblast phenotype in cultured fetal rat calvaria cells.

Rat calvaria osteoblasts derived from 21-day-old fetal rat pups undergo a temporal expression of markers of the osteoblast phenotype during a 5 week culture period. Alkaline phosphatase and osteocalcin are sequentially expressed in relation to collagen accumulation and mineralization. This pattern of expression of these osteoblast parameters in cultured rat osteoblasts (ROB) is analogous to that seen in vivo in developing fetal rat calvaria tissue (Yoon et. al: Biochem. Biophis. Res. Commun. 148:1129, 1987) and is similar to that observed in cultures of subcultivated 16-day-old embryonic chick calvaria-derived osteoblasts (COB) (Gerstenfeld, et.al: Dev. Biol. 122:46, 1987). While the cellular organization of subcultivated COB and primary ROB cultures are somewhat different, the temporal expression of the parameters remains. Both the rat and chick culture systems support formation of matrix mineralization even in the absence of beta-glycerol-phosphate. A systematic examination of factors which constitute conditions supporting complete expression of the osteoblast phenotype in ROB cultures indicate requirements for specific serum lots, ascorbic acid and the ordered deposition of mineral in the extracellular matrix. The present studies suggest that formation of a collagenous matrix, dependent on ascorbic acid, is requisite for expression of the osteoblast phenotype. In ROB cultures, expression of osteocalcin synthesis occurs subsequent to initiation of alkaline phosphatase activity and accompanies the formation of mineralized nodules. Thus, extracellular matrix mineralization (deposition of hydroxyapatite) is required for complete development of the osteoblast phenotype, as reflected by a 200-fold increase in osteocalcin synthesis. These data show the temporal expression of the various osteoblast parameters during the formation and mineralization of an extracellular matrix can provide markers reflective of various stages of osteoblast differentiation/maturation in vitro.

Alkaline Phosphatase↗

PubMed1990

Progressive development of the rat osteoblast phenotype in vitro: reciprocal relationships in expression of genes associated with osteoblast proliferation and differentiation during formation of the bone extracellular matrix.

The relationship of cell proliferation to the temporal expression of genes characterizing a developmental sequence associated with bone cell differentiation was examined in primary diploid cultures of fetal calvarial derived osteoblasts by the combined use of autoradiography, histochemistry, biochemistry, and mRNA assays of osteoblast cell growth and phenotypic genes. Modifications in gene expression define a developmental sequence that has 1) three principle periods--proliferation, extracellular matrix maturation, and mineralization--and 2) two restriction points to which the cells can progress but cannot pass without further signals--the first when proliferation is down-regulated and gene expression associated with extracellular matrix maturation is induced, and the second when mineralization occurs. Initially, actively proliferating cells, expressing cell cycle- and cell growth-regulated genes, produce a fibronectin/type I collagen extracellular matrix. A reciprocal and functionally coupled relationship between the decline in proliferative activity and the subsequent induction of genes associated with matrix maturation and mineralization is supported by 1) a temporal sequence of events in which there is an enhanced expression of alkaline phosphatase immediately following the proliferative period, and later, an increased expression of osteocalcin and osteopontin at the onset of mineralization; 2) increased expression of a specific subset of osteoblast phenotype markers, alkaline phosphatase and osteopontin, when proliferation is inhibited by hydroxyurea; and 3) enhanced levels of expression of the osteoblast markers as a function of ascorbic acid-induced collagen deposition, suggesting that the extracellular matrix contributes to both the shutdown of proliferation and the development of the osteoblast phenotype.

Alkaline Phosphatase↗

PubMed1989

Prenatal exposure to phenytoin and its effect on postnatal growth and craniofacial proportion in the rat.

Neonatal rats exposed prenatally to phenytoin (PHT) have been reported to have craniofacial abnormalities and growth retardation [Lorente et al.: Teratology 24:169-180, 1981]. This study reports on the persistence of these effects in the adult rat. Pregnant Sprague-Dawley rats were intubated on gestational days 9, 11, and 13 with 1,000 mg/kg PHT suspended in 1% carboxymethylcellulose (CMC). Six male and six female exposed offspring (PHT) and an equal number of control animals (CMC) were weighed through postnatal day 135, at which point they were killed and the skeletons were prepared for analysis. The PHT-exposed animals had reduced weights at all time points with the males more severely affected. A normal adolescent growth spurt was not observed in the exposed group. Absent or rudimentary lacrimal bones and nasolacrimal canals were note in all PHT-exposed rats. This contributed to the recessed positioning of the eyes that was grossly apparent. In addition, shorter and broader frontal bones in the PHT animals led to the appearance of hypertelorism. Ratios of craniofacial dimensions obtained by direct measurement of the skulls showed that the PHT offspring were significantly different in proportion from their control counterparts. The PHT skulls were smaller for body size with reduced facial height and broader midfacial regions. A unique craniofacial pattern was observed in the experimental offspring. Normal sexual dimorphism in craniofacial pattern was not expressed in the PHT group. These studies suggest that prenatal phenytoin exposure in the rat may interfere with the full expression of normal dimorphism based on gender and confirms the toxic effect of this drug on postnatal growth, adult body proportion, and craniofacial geometry.

Abnormalities, Drug-Induced↗

PubMed1986

The effects of nitrous oxide after exposure during middle and late gestation.

Recent evidence has indicated that the anesthetic gas nitrous oxide (N2O) is teratogenic to rats if exposed during the organogenesis phase of gestation. Little is known, however, of the anatomical or functional consequences of exposures occurring later in gestation when the brain is developing. Timed pregnant Sprague-Dawley rats were exposed to 75% N2O/25% O2 using one of the following protocols: 24 hr exposures on gestational days 11-15 or 16-20; or 8 hr exposures on gestational days 9-13, 11-15, 14-15 or day 15 only. Both 24 hr exposure protocols significantly reduced fetal and maternal body weight, an effect not observed after the 8 hr exposures. No N2O exposure resulted in gross morphological or skeletal changes. Likewise, no significant effects on total protein and DNA levels in fetal liver and brain tissues could be found subsequent to 24 hr exposures on days 16-20; or on one, three or six days following an 8 hr exposure on day 15. Evaluations of postnatal growth and neurological development in pups prenatally exposed for 8 hr on days 14 and 15 revealed two noteworthy effects. Their rate of growth in body weight was greater with respect to controls between the ages of 14 and 21 days, especially in the males. Also, reflex suspension was reduced, significantly so in the females. In conclusion, unlike 24 hr exposures, multiple 8 hr exposures to nitrous oxide during the middle to late stages of gestation did not produce effects detectable with standard teratological measures. Subtle differences in growth rate and reflex suspension, however, indicated that normal development had been interrupted, but its clear distinction as a lasting effect requires additional measures of function.

Animals↗

PubMed1986

Behavioral toxicity of nitrous oxide in rats following prenatal exposure.

Nitrous oxide (N2O) exposure has been associated with neurotoxicity, especially peripheral neuropathy, in both humans and animals. The effects of this anesthetic gas on the central nervous system (CNS) and spontaneous behavior, however, have yet to be delineated. Timed-pregnant Sprague-Dawley rats were exposed to 75% N2O/25% O2 on gestational days 14 and 15 or day 15 only for eight hours per day. The offspring were tested at one and five months of age; their spontaneous behavior in a novel environment was recorded in the residential maze and using time-lapse photography. The results indicated that in utero exposure to N2O permanently altered the spontaneous motor output of the CNS. This effect was most prominent in 5 month old animals, and females were affected more than males. Exposures on gestational days 14 and 15 produced an effect that was not only greater but also qualitatively different than that produced by exposure on day 15 only. The two-day exposure induced hyperactivity in both sexes, whereas the one-day exposure induced hyperactivity in the males and slight hypoactivity in the females. These behavioral changes were not accompanied by physical abnormalities but nonetheless were lasting effects in need of further consideration.

Aging↗

PubMed1984

Effect of in utero exposure to anticonvulsants on craniofacial development and growth.

It has been widely reported that some children exposed to anticonvulsants in utero have a characteristic pattern of craniofacial anomalies including a broad, low nasal bridge with a short upturned nose, wide mouth, low set ears, epicanthal folds, and ocular hypertelorism, while others show no evidence of craniofacial abnormalities. The purpose of this paper is to define the craniofacial features in nine exposed children using anthropometric measurements and frontal and lateral cephalometric radiographs. These children were identified at birth as part of a prospective study of infants exposed to anticonvulsants at the Boston Hospital for Women (now part of the Brigham and Women's Hospital). At birth, none of these infants had any major malformations; at 4 to 10 years of age, none demonstrated any growth deficiency or mental deficiency, and all external craniofacial measurements were within the normal range. However, cephalometric analyses demonstrated a pattern of reduced bony interorbital distance, maxillary size, mandibular length, cranial base and skull size, and a reduction in nose dimensions when compared to data of normal populations. This study demonstrates the inadequacy of external measurements in determining the details of underlying craniofacial architecture. The data also suggest that a subtle craniofacial change occurs in exposed children which is characterized by a decrease in bony interorbital distance and the size of the cranial base and maxilla with concomitant decreases in nose and mandibular dimensions.

Abnormalities, Drug-Induced↗