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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Much information has emerged over the years concerning the teratogenicity of acute and chronic alcohol exposure during pregnancy. Both alcohol and its primary metabolite, acetaldehyde, are teratogenic. Exposure during pregnancy may lead to fetal alcohol syndrome (FAS), and this is said to occur in a substantial proportion of infants born to mothers who are chronic, heavy daily drinkers. Such infants usually survive to birth but are mentally retarded, often display growth retardation and additionally display a characteristic range of clinical features, principally craniofacial abnormalities and neurological damage. We have recently been interested in the effect of exposure of pregnant female mice to a single high level of alcohol during pregnancy, equivalent to an episode of 'binge' drinking, on the optic nerve, and believe that our findings, which are outlined in the first part of this review, may shed important light on the pathogenesis of some of the ocular features characteristically seen in infants with this syndrome. What is not generally appreciated, is that exposure to alcohol and other 'spindle-active' substances that have a similar action on the meiotic spindle apparatus during the menstrual cycle before conception can induce chromosome segregation errors in the ovulated oocyte. The successful fertilization of such eggs consequently results in the production of aneuploid embryos, which have a very high chance of being spontaneously aborted during the first trimester of pregnancy. Those relatively few aneuploid conceptuses that survive to term invariably show moderate to severe degrees of mental retardation, craniofacial and other abnormalities, as well as having a significantly reduced life expectancy. The findings from our experimental studies that have been carried out in mice draw attention to important principles which are of general applicability to the situation in the human. These findings, and our conclusions drawn from them, are discussed in detail in the second part of this review.
Alcohol Alcohol
PMID:The teratogenic effects of alcohol following exposure during pregnancy, and its influence on the chromosome constitution of the pre-ovulatory egg. 910 5

Prenatal exposure of human brain to ethanol impairs neuronal migration and differentiation and causes mental retardation. The present results indicate that the adverse effects of ethanol on brain development may be partly due to the ethanol-induced disturbance of neuronal interaction with laminin, a protein involved in neuronal migration and axon guidance. This report shows that physiological concentrations (IC50 = 28 mM) of ethanol inhibit neurite outgrowth and neuronal migration of the rat cerebellar granule neurons on a laminin substratum. The ethanol-treated granule neurons undergo apoptosis, degrade their laminin substratum, and appear to release and bind increased amounts of the B2-chain-derived peptides along their surfaces. A protease inhibitor aprotinin, and the NMDA receptor channel, and voltage-gated calcium channel antagonist MK801 partially protect cerebellar granule neurons from ethanol-induced neurotoxicity. These results imply that ethanol-treated granule neurons resemble the granule neurons of the homozygous weaver mouse cerebellum with respect to their apoptosis, laminin expression, and partial rescue by approtinin and MK-801. Thus, ethanol may influence neuronal survival and neurite outgrowth via molecular pathways similar to those involved in neuronal death in other neurodegenerative processes of the central nervous system.
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PMID:Ethanol-exposed central neurons fail to migrate and undergo apoptosis. 918 67

The development of the fetal central nervous system can be effected by drugs. In this paper we review the neurological consequences of intrauterine exposure to alcohol, cocaine, opiates and marijuana. Ethanol causes the fetal alcohol syndrome: mental retardation, intrauterine and postnatal growth retardation, and peculiar dysmorphic features. Is pathogenesis has been explained on the basis of maternal nutritional deficiencies or due to abnormalities in the conversion of ethanol to aldehyde, or abnormalities in the metabolism of prostaglandins or retinoic acid, the neurotransmitter systems, the neuronal excitotoxic activity, the development of the white matter, the production of gangliosides, and/or genetic regulation cell-cell adhesion. Cocaine has been related to congenital malformations, neurologic abnormalities during the neonatal period and psychomotor and cognitive development deficits. Characteristic dysmorphic features and a higher incidence of the sudden infant death syndrome (SIDS) have also been described. The following mechanisms have been implicated in the pathogenesis: vascular effects, superoxide formation, chelation of calcium ion channels, and abnormalities in the production of glycosphingolipids, the synthesis of DNA, the functioning of neurotransmitter systems, the neuronal growth and differentiation, the neuronal excitotoxic activity and/or the expression of early immediate genes. Opiates produce intrauterine and postnatal growth retardation, neonatal abstinence syndrome, and deficits of the psychomotor and cognitive development. They also increase the incidence of SIDS. The pathogenesis has been related to abnormalities in the sensitivity of the locus ceruleus, the functioning of the neurotransmitter systems, and/or the expression of early immediate genes. Marijuana has been associated with intrauterine growth retardation, dysmorphic features, and abnormalities of the behavior during the neonatal period, the psychomotor and cognitive development, and the sleep. The pathogenesis is thought to be due to an action upon specific receptors, or upon the neurotransmitter systems, and/or to an increase in the production of carbon monoxide. The best treatment of the syndrome of intrauterine exposure to drugs in the prophylaxis. The identification of emotional and drug addiction problems in the mother can avoid disastrous consequences. The care of these children is complex and requires a good pediatric follow-up and an early intervention program while the mother on the parents continue with the drug addiction therapy. The coordinations of all the necessary services with the active participation of social workers, physicians, educators and teachers is crucial for a successful treatment.
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PMID:[Intrauterine exposure to drugs]. 920 93

Fetal alcohol syndrome is one of the leading causes of mental retardation in the United States, but the pathogenesis of the associated brain damage is unknown. We tested the hypothesis that neonatal cerebrovascular responses to CO2 and/or hypoxia may be altered by moderate chronic maternal ethanol exposure early in gestation. We studied 26 newborn lambs (1-4 d old). Their mothers had received daily i.v. infusions of either ethanol (1 g/kg; ethanol concentration = 167 +/- 3 mg/dL; mean +/- SEM) or a similar volume of saline for 3 wk during the first trimester. In nine lambs, we studied cerebral responses to CO2 (saline, n = 4; ethanol, n = 5) and in 17 lambs, cerebral responses to hypoxia (saline, n = 7; ethanol, n = 10). Cerebrovascular responses to CO2 were not different between the groups. However, the cerebral vasodilatory response to hypoxemia was significantly attenuated in the ethanol lambs, such that cerebral O2 delivery was not maintained. During severe hypoxia (arterial PO2 = 30 mm Hg), cerebral blood flow increased 106 +/- 23% (mean +/- SEM) above baseline in the saline-treated group, but increased only 32 +/- 15% above baseline in the ethanol-treated group (p < 0.02). Similarly, cerebrovascular resistance in the saline group decreased 52 +/- 6% from baseline, but decreased only 16 +/- 11% in the ethanol group (p < 0.02). We conclude that moderate maternal ethanol infusion early in pregnancy attenuates neonatal hypoxic, but not CO2, cerebrovascular responsivity.
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PMID:Newborn cerebrovascular responses after first trimester moderate maternal ethanol exposure in sheep. 921 35

In the USA, fetal alcohol syndrome (FAS) is the leading known cause of mental retardation. FAS is estimated to affect 4000 infants yearly in the USA with an additional 7000 children suffering various forms of fetal alcohol effects in the absence of the full syndrome. A comparable incidence would be expected in other industrialized countries, but essentially no data are available from either developing or third world countries. An understanding of the biochemical causes of FAS has been slow to develop, but progress has been made toward a molecular causation theory of FAS. This paper summarizes much of the current work as to the effects of fetal ethanol exposure on mitotic and metabolic parameters as well as ethanol's effect on the cellular signalling pathways thought to regulate these processes. Based upon these studies, it is apparent that exposure of embryonic tissue to ethanol results in decreased growth and that alcohol adversely affects a multitude of cellular functions critical for the growth of the developing organism, including inhibition of protein and DNA synthesis. In addition, ethanol alters the uptake of critical nutrients such as glucose and amino acids and causes changes in several kinase-mediated signal transduction pathways that regulate these biochemical processes.
Alcohol Alcohol
PMID:Metabolic and mitotic changes associated with the fetal alcohol syndrome. 926 50

Fetal alcohol syndrome is the leading cause of mental retardation in the United States. The tragedy is that while FAS is irreversible, it is 100% preventable. FAS is caused by maternal consumption of alcohol during pregnancy. Alcohol is a teratogen and acts in different ways to produce physical and central nervous system malformations and defects in the developing embryo and fetus. FAS is characterized by a history of maternal alcohol ingestion, central nervous system dysfunction, growth deficiencies, and specific physical anomalies. Adolescents and adults with FAS have behavioral problems that differentiate them from other mentally disabled individuals. Nurse practitioners can have an impact on the prevalence of FAS by educating clients about FAS and its relationship to alcohol consumption. NPs need to carefully identify high-risk women and their partners before a pregnancy occurs and assist with interventions to stop active alcoholism or alcohol use during pregnancy. NPs have the capability to decrease the severity of alcohol's effects during pregnancy through education, counseling, and intervention. NPs have the skills to work with case-finding and early identification of infants and children who display signs and symptoms of FAS. With such case-finding, early identification, and prompt referral to the appropriate diagnostic and/or supportive community agencies, individuals with FAS can receive timely intervention to minimize the effects of FAS. Adults with behavioral problems can be assessed for FAS and referred for appropriate assistance as well. Finally, NPs can facilitate public awareness of FAS through educational efforts with individuals, families, and communities.
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PMID:Fetal alcohol syndrome: the nurse practitioner perspective. 928 78

Exposure to ethanol during pregnancy is detrimental to brain development. Individuals affected by the Fetal Alcohol Syndrome present a number of central nervous system dysfunctions including microencephaly and mental retardation. Studies on the mechanisms of ethanol's developmental neurotoxicity have focused on its interaction with neurons; however, emerging evidence is suggesting that ethanol can significantly affect glial cells as well. A number of in vitro studies have shown that ethanol can inhibit the proliferation of various glial cells (mostly primary astrocytes or astrocytoma cells) at relatively high concentrations (100-200 mM). On the other hand, proliferation induced by some, but not all mitogens, is inhibited by low concentrations (10-50 mM) of ethanol. These inhibitory effects of ethanol may contribute to its developmental neurotoxicity observed following in vivo exposure. Animal models have indeed shown that ethanol causes microencephaly when given during the brain growth spurt, a period of brain development characterized by astroglial proliferation and maturation.
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PMID:The effects of ethanol on glial cell proliferation: relevance to the fetal alcohol syndrome. 932 12

Ethanol exposure during development is teratogenic. The central nervous system (CNS) is particularly susceptible to ethanol toxicity. In fact, heavy gestational ethanol consumption is one of the leading known causes of mental retardation in the Western world. Ethanol exposure disrupts the proliferation of glia and neuronal precursors in the developing CNS. Depending upon cell population and blood ethanol concentration, ethanol can either inhibit or stimulate cell proliferation. Two features of cell proliferation that are affected by ethanol exposure are the growth fraction (the proportion of cells that is actively cycling) and the cell cycle kinetics, particularly in the length of the G1 phase of the cell cycle. Cell proliferation in the developing CNS reflects the action of positive (mitogenic growth factors) and negative (anti-proliferative factors) regulators. Increasing evidence shows that ethanol interferes with the action of growth factors. In vitro systems are a good model to investigate ethanol neurotoxicity, since the effects of ethanol on cultured cells parallel the effects of ethanol in the developing CNS. The inhibitory effects of ethanol on cell proliferation may result from interference with mitogenic growth factors (e.g., bFGF, EGF, PDGF, IGF-I). Conversely, the stimulatory effects of ethanol may result from the interference with growth inhibiting factors (e.g., TGFbeta1). Interestingly, both in vivo and in vitro studies show that proliferating neural cells display differential sensitivity to ethanol. This differential sensitivity correlates with their response to mitogenic growth factors; that is, cells that are actively regulated by mitogenic growth factors are much more susceptible to ethanol than cells that are less or unresponsive to such factors. Ethanol interference with growth factor action could occur at three levels: ligand production, receptor expression, and/or signal transduction. Thus, ethanol-induced alterations in the developing CNS that characterize fetal alcohol syndrome apparently result from alterations in the regulatory action of growth factors.
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PMID:Growth factor-mediated neural proliferation: target of ethanol toxicity. 962 17

Fetal alcohol syndrome is one of the leading causes of birth defects in this country. Children exposed to alcohol in utero suffer from growth and mental retardation, physical abnormalities, and immune dysfunction. Previous work from this laboratory demonstrated that B lymphopoiesis is delayed in mice exposed to alcohol in utero. The deficit in B-cell development was apparent shortly after birth and extended to well after weaning. Because lymphopoiesis begins in the fetal liver, the current study was done to determine if fetal B-cell development was affected as well by in utero exposure to alcohol. We now show that the effects of in utero alcohol exposure on B lymphopoiesis do not become apparent until late in gestation. Flow cytometry was used to enumerate several intermediates in the B-cell developmental pathway. These phenotypic analyses showed that before day 17 of gestation, B-lineage intermediates developed normally when compared with control animals. However, between days 17 and 18 of gestation, an abnormality in the population dynamics of B-lineage intermediates became apparent in the fetal liver of alcohol-exposed mice. Early intermediates in the B-cell developmental pathway were present in normal numbers; however, the more mature progenitors as well as B cells were decreased in number by gestational day 18. These data suggest that in utero alcohol exposure disrupts the ability of B-lineage intermediates to progress along the developmental pathway to maturity, thereby leaving the animal immunocompromised at birth.
Alcohol Clin Exp Res 1998 Nov
PMID:Effects of in utero alcohol exposure on B-cell development in the murine fetal liver. 983 84

Fetal alcohol syndrome is a major cause of mental retardation. We investigated possible long-lasting effects of alcohol on the hippocampus using a model for human third trimester brain development. Treatment of neonatal rats with an ethanol vapor atmosphere of 39.4+/-2.6 mg ethanol/liter of air for 3 h a day from postnatal day 4 through 9 produced daily blood ethanol levels of 351+/-14 mg/dL. Separation control animals were removed from their mothers in parallel with the ethanol vapor treatment, while suckle controls were left to develop normally. We prepared hippocampal slices from these animals between postnatal days 45 and 60 and recorded extracellular responses to Schaffer collateral stimulation. The maximum population spike in the CA1 pyramidal region and population excitatory postsynaptic potentials in the stratum radiatum did not differ significantly between groups. However, slices prepared from ethanol-treated rats as opposed to separation and suckle controls required larger stimulus currents to produce normal postsynaptic responses. In addition, the ratio of the population excitatory postsynaptic potential (pEPSP) slope to the presynaptic volley was significantly reduced in ethanol-treated rats. Ethanol vapor-treated rats and separation control rats did not exhibit any significant changes in long-term potentiation or paired-pulse potentiation compared with normal suckle controls. These results suggest that early postnatal ethanol treatment produces a long-lasting reduction in synaptic efficacy but not plasticity.
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PMID:Ethanol exposure during the third trimester equivalent results in long-lasting decreased synaptic efficacy but not plasticity in the CA1 region of the rat hippocampus. 1002 83


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