Dopamine neuron agenesis in Nurr1-deficient mice.

Dopamine neurons of the substantia nigra and ventral tegmental area regulate movement and affective behavior and degenerate in Parkinson's disease. The orphan nuclear receptor Nurr1 was shown to be expressed in developing dopamine neurons before the appearance of known phenotypic markers for these cells. Mice lacking Nurr1 failed to generate midbrain dopaminergic neurons, were hypoactive, and died soon after birth. Nurr1 expression continued into adulthood, and brains of heterozygous animals, otherwise apparently healthy, contained reduced dopamine levels. These results suggest that putative Nurr1 ligands may be useful for treatment of Parkinson's disease and other disorders of midbrain dopamine circuitry.

Docosahexaenoic acid, a ligand for the retinoid X receptor in mouse brain.

The retinoid X receptor (RXR) is a nuclear receptor that functions as a ligand-activated transcription factor. Little is known about the ligands that activate RXR in vivo. Here, we identified a factor in brain tissue from adult mice that activates RXR in cell-based assays. Purification and analysis of the factor by mass spectrometry revealed that it is docosahexaenoic acid (DHA), a long-chain polyunsaturated fatty acid that is highly enriched in the adult mammalian brain. Previous work has shown that DHA is essential for brain maturation, and deficiency of DHA in both rodents and humans leads to impaired spatial learning and other abnormalities. These data suggest that DHA may influence neural function through activation of an RXR signaling pathway.

Neuropsychological Development in Patients with Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase (LCHAD) Deficiency.

BACKGROUND: Reports on cognitive outcomes in long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) are scarce. We present results from neuropsychological assessments of eight patients diagnosed with LCHADD prior to newborn screening with regard to clinical disease severity. METHODS: Intellectual ability and adaptive and executive functions were assessed using age-appropriate Wechsler Scales, Adaptive Behavior Assessment Scales (ABAS), and Behavior Rating Inventory of Executive Function (BRIEF). RESULTS: Five patients performed in the normal range on IQ tests but with lower scores on verbal working memory. In addition, they had lower parent-rated adaptive and executive functions.Three patients had intellectual disabilities with IQs below normal and/or autism spectrum disorders. In addition, they had low results on parent-rated adaptive functions. (Two of these patients had epilepsy.) Conclusions: Patients with LCHADD seem to have a specific cognitive pattern, with presentation as intellectual disability and specific autistic deficiencies or a normal IQ with weaknesses in auditive verbal memory and adaptive and executive functions. Future studies are warranted to investigate whether newborn screening programs and early treatment may promote improved neuropsychological development and outcomes.

Retinoid X receptor heterodimerization and developmental expression distinguish the orphan nuclear receptors NGFI-B, Nurr1, and Nor1.

NGFI-B, Nurr1, and Nor1 are three closely related orphan members of the steroid/thyroid hormone receptor superfamily. These receptors can bind to DNA as monomers and exhibit constitutive transcriptional activity. Moreover, two of the receptors, NGFI-B and Nurr1, have previously been shown to form heterodimers with the retinoid X receptor (RXR). Such heterodimers as well as complexes formed between RXR and the all-trans retinoic acid receptor bind to DNA response elements composed of direct repeats spaced by five nucleotides (DR5). However, whereas retinoic acid receptor can inhibit ligand-dependent RXR activation, NGFI-B and Nurr1 allow efficient RXR activation through DR5 elements and thus define a distinct pathway for vitamin A signaling. In this study we demonstrate that the most recently identified member of the subfamily, Nor1, shows similar monomer DNA-binding and constitutive transactivation properties as NGFI-B and Nurr1. In contrast, however, Nor1 is unable to promote RXR signaling due to its inability to form heterodimers with RXR. To begin to understand the physiological implications of these functional differences we used in situ hybridization to compare the distribution of Nor1, NGFI-B, and Nurr1 messenger RNAs during different developmental stages. The receptors are expressed in both distinct and overlapping patterns, predominantly in the central nervous system. Notably, Nurr1 is expressed in the prenatal ventral midbrain in a region that gives rise to dopaminergic neurons. Nor1 is also expressed during embryonic development, and all three receptors show a complex distribution in the postnatal brain. Furthermore, Nor1 colocalizes with NGFI-B in the adrenal glands and thymus, two tissues in which NGFI-B has been suggested to be functionally important. These data may indicate redundancy between members of the NGFI-B/Nurr1/Nor1 subfamily and could explain why no phenotypic disturbances have yet been found in mice in which the NGFI-B gene has been inactivated.

Constitutive expression of interleukin-1alpha messenger ribonucleic acid in rat Sertoli cells is dependent upon interaction with germ cells.

Interleukin-1 (IL-1), a proinflammatory cytokine originally isolated as a product of activated mononuclear phagocytes, consists of two distinct agonist proteins, IL-1alpha and IL-1beta, of which IL-1beta is the major inducible IL-1 protein produced by macrophages. We show here that mRNA of IL-1alpha, but not IL-1beta, is constitutively expressed by the intact rat testis and localize the transcript to Sertoli cells as confirmed by a novel squash technique. The expression is developmentally regulated and appears only after postnatal day 20 in the rat testis, corresponding to onset of puberty. IL-1alpha mRNA shows a stage-dependent expression pattern during the cycle of the seminiferous epithelium. It is low or absent in stage VII, but present in all other stages of the cycle. The same stage-dependent distribution was also observed at the protein level when bioactive IL-1 was measured in extracts of accurately defined one millimeter segments of seminiferous tubules. No IL-1alpha mRNA was detected in adult rat testes after germ cell depletion by fetal irradiation or cytostatic drug treatment. Because stage VII is the only segment of the seminiferous tubules lacking DNA replication, we propose that IL-1alpha is involved in this event during mitosis and meiosis of spermatogenesis and that its expression is dependent upon interactions between Sertoli cells and germ cells.

Localization of cellular retinoid-binding proteins suggests specific roles for retinoids in the adult central nervous system.

Retinoic acid, the active metabolite of retinoids (vitamin A compounds), is thought to act as a gene regulator via ligand-activated transcription factors. In order to investigate possible roles of retinoids and retinoid-controlled gene expression in brain function, we have used immunohistochemistry to localize the possible presence of two intracellular retinoid-binding proteins, cellular retinol-binding protein type I and cellular retinoic acid-binding protein type I, in the adult rat central nervous system. We find a widespread, yet distinct, presence of these two binding proteins in the brain and spinal cord. Most of the immunoreactivity is neuronal, including cell somata, as well as dendritic and axonal processes and axon terminals. Cellular retinol-binding protein type I-immunoreactivity is also found in the walls of cerebral blood vessels, the meninges, the choroid plexus, certain ependymal cells, tanocytes and certain other glial elements. The cellular retinol-binding protein type I- and cellular retinoic acid-binding protein type I-immunoreactivity patterns appear to be almost exclusively non-overlapping. Very strong cellular retinol-binding protein type I-immunoreactivity is found in the dendritic layers of the hippocampal formation and dentate gyrus. Cellular retinol-binding protein type I-immunoreactivity is also present in layer 5 cortical pyramidal neurons and neurons in the glomerular layer of the olfactory bulb. Many other areas, e.g. hypothalamic nuclei and amygdala areas, contain networks of varicose cellular retinol-binding protein type I-immunoreactive nerve fibers. The medial amygdaloid nucleus contains strongly cellular retinol-binding protein type I-positive neurons. Cellular retinoic acid-binding protein type I-immunoreactivity is more restricted in the adult brain. Strong cellular retinoic acid-binding protein type I-immunoreactivity is, however, found in a population of medium-sized neurons scattered throughout the striatum, in neurons in the glomerular layer of the olfactory bulb, the olfactory nerve and in a group of nerve cells close to the third ventricle in hypothalamus. The remarkably selective patterns of cellular retinol-binding protein type I- and cellular retinoic acid-binding protein type I-immunoreactivity discovered in the adult rat brain suggest that retinoids have important roles as regulators of gene expression in normal brain function. The high levels of cellular retinol-binding protein type I-immunoreactivity found in hippocampus suggest that one such role might relate to brain plasticity.

Cellular expression of the immediate early transcription factors Nurr1 and NGFI-B suggests a gene regulatory role in several brain regions including the nigrostriatal dopamine system.

Nurr1 and NGFI-B are closely related orphan members of the steroid-thyroid hormone receptor family involved in immediate early responses to stimuli such as growth factors. In-situ hybridization in the developing and adult mouse and rat demonstrated Nurr1 mRNA in several regions during early central nervous system (CNS) development. Expression persisted through the pre- and postnatal periods and was also found in several areas in the adult CNS. Positive areas include the olfactory bulb, parts of the cortex, the hippocampal formation and substantia nigra where Nurr1 and tyrosine hydroxylase mRNAs were co-expressed. 6-Hydroxydopamine-induced degeneration of mesencephalic dopamine neurons led to a corresponding loss of Nurr1 mRNA, demonstrating a link between Nurr1 and dopaminergic neurons. NGFI-B mRNA was not found in the prenatal CNS but was highly expressed in the adult brain in many areas including the olfactory bulb, cortex, basal ganglia and hippocampus. The spatiotemporal distribution of Nurr1 and NGFI-B mRNAs suggests that these transcription factors are involved in the development and maturation of specific sets of CNS neurons. The experimental data imply that one of these functions may be to control gene regulatory events important for development and function of those neurons that degenerate in patients with Parkinson's disease.

IGF-1 influences olfactory bulb maturation. Evidence from anti-IGF-1 antibody treatment of developing grafts in oculo.

Recent studies have indicated that both insulin-like growth factor-1 (IGF-1) and IGF-1 receptor mRNA are abundant in developing and adult olfactory bulbs, and that IGF-1 receptor mRNA is abundant in the prenatal cerebral cortex. To examine the potential role of IGF-1 in development of a central nervous system region rich in IGF-1 and its receptor (the olfactory bulb), as compared to one in which IGF-1 is less abundant (the cerebral cortex), tissue pieces of these two central nervous system areas from E15-E17 rat fetuses were transplanted into the anterior chamber of the eye of adult host rats. The transplants were treated with either a total of 300 ng truncated IGF-1, two different IGF-1 polyclonal antisera, two different non-immune sera, a total of 15 micrograms IGF binding protein-1, or vehicle alone. Treatments were administered by preincubation just prior to grafting and by 5 microliters injections into the anterior chamber on days 5, 10 and 15 postgrafting. Olfactory bulb grafts treated with either of the two IGF-1 antisera grew significantly larger than grafts receiving any other treatment. No enhancement of graft size was seen in E16-E17 parietal cortex grafts after IGF-1 antibody treatment. Immunohistochemical studies revealed no difference between the treatments with regard to glial fibrillary acidic protein-, tyrosine hydroxylase- or neurofilament-immunoreactivity within the olfactory bulb grafts. Since, in the olfactory bulb the presumed reduction of endogenous IGF-1 achieved by antibody treatment caused enhanced growth, we suggest that the presence of appropriate endogenous levels of IGF-1 in this area induces maturation. This mechanism is not operative in all brain areas since it was not seen in cortex cerebri grafts. Thus, endogenous IGF-1 appears to influence brain development in a regionally specific manner.

Erythrocyte glutathione synthetase in 5-oxoprolinuria: kinetic studies of the mutant enzyme and detection of heterozygotes.

The primary metabolic defect in 5-oxoprolinuria is a generalized deficiency of glutathione synthetase. The activity of this enzyme was determined in cell-free extracts of erythrocytes from patients with 5-oxoprolinuria, their parents and a sibling as well as from normal control individuals. The following activities (pkat/mg of hemoglobin) for glutathione synthetase were obtained: homozygotes mean 0.10 (range 0.07-0.12), heterozygotes mean 3.1 (range 2.8-3.7) and control individuals mean 6.1 (range 5.4-6.7). These results indicate that 5-oxoprolinuria, i.e. the defective gluthione synthetase gene(s), is transmitted by autosomal recessive inheritance. Studies of the kinetics of the low remaining activity of erythrocyte glutathione synthetase in patients with 5-oxoprolinuria failed to reveal defective affinity for glycine, gamma-glutamyl-alpha-aminobutyrate, ATP and Mg2+ ions. Furthermore, the pH optimum, time curves and temperature dependence for the mutant enzyme activity did not significantly differ from the corresponding parameters observed with normal enzyme.

Environmental pollution and child health in the Aral Sea region in Kazakhstan.

The deterioration of human health with increasing infant mortality rate, declining life expectancy at birth and increasing prevalence of serious infectious diseases in Russia and other former Soviet Republics is thought to be due to a combination of several factors such as inadequate nutrition, poor sanitation, collapse of the health care system and pollution from Soviet agriculture and industries. In the Aral Sea region in Kazakhstan, the environmental problems are of near catastrophic proportions. As a result of the implementation of a massive irrigation scheme to support the cotton fields in the former desert land, the water flow to the Aral Sea was reduced to less than half. Industrial pollutants such as PCB-compounds and heavy metals, but also the use of large quantities of pesticides to control parasites and weeds have accumulated not only in water, but also in soil and have been deposited over large areas by atmospheric transport to enter the food chain leading to humans. In a study of 15 children and of an additional 12 children referred from the region of the Aral Sea to the National Children's Rehabilitation Center in Almaty with symptoms and signs of 'ecological disease', we have found that the concentration of PCB compounds in the blood lipids is elevated in relation to healthy Swedish children. In addition, the blood lipid concentration of the beta-isomer of the hexachlorocyclohexanes was extremely high and of DDT-compounds was elevated up to 20 times. The concentrations of lead in red blood cells was moderately elevated and that of cadmium slightly elevated compared to the findings in Stockholm children. To study the role of these pollutants in the diseases found in children from the Aral Sea region accurate epidemiological studies have to be performed.

Predictive indicators for adjustment in 4-year-old children whose mothers used amphetamine during pregnancy.

Psychosocial factors that could be used as predictive indicators for adjustment of 4-year-old children whose mothers had used amphetamine during pregnancy were studied by means of simple and multivariate correlation analyses. The following statistically significant correlations were found: Length of maternal alcohol and drug abuse during pregnancy was correlated negatively with the child's adjustment as were numbers of paternal criminal convictions, number of stress factors of the mother, and number of earlier children born to the mother. Paternal criminality was associated with the outcome, regardless of amount of contact between father and child.

The influence of environmental factors on behavioural problems in 8-year-old children exposed to amphetamine during fetal life.

Sixty-five children born to women who all used amphetamine during pregnancy were followed prospectively up to the age of 8 years. There was a statistically significant correlation between the extent (among and duration) of amphetamine exposure during fetal life and psychometric tests, aggressive behavior, adjustment and general assessment, indicating a worse outcome for children who had been more exposed to the drug. Alcohol use during pregnancy as well as attitude towards pregnancy also showed a statistical correlation to the outcome. Predictors of the child's psychosocial environment were few and only maternal psychiatric treatment, alcohol abuse and number of custodians correlated with aggressive behavior and general assessment.

Experimental intestinal obstruction in rats. Studies on structure and disaccharidase activities.

An experimental model of congenital intestinal obstruction (CIO) was created in rats by means of fetal intrauterine surgery between the 16th and 20th days of gestation. By the use of a microsurgical technique areas at the mid-jejunum or the jejuno-ileal junction were infarcted by coagulation of mesenteric vessels. Gestation was terminated by Cesarean section within 24 hours before expected term to avoid cannibalism. The structure of the intestinal mucosal cells proximal and distal to the CIO at the light microscopy as well as the ultrastructure level was not changed indicating that the surgical method was successful. The activities of the brush border enzymes, maltase and lactase were significantly reduced distal to the obstruction as compared to controls. Proximal to the obstruction lactase was the only enzyme showing reduced activity in comparison to controls. These findings were not dependent on the localization of the obstruction or when it was performed and suggest that CIO causes selective changes of the biochemical properties of the cell membrane. The results are in agreement with the findings of disaccharidase activities in biopsies taken from human infants with CIO and point to the importance of a normal intestinal passage for the development of brush border enzymes.

Delivery outcome of women working in laboratories during pregnancy.

By record-linkage of the 1975 Swedish census and the Medical Birth Register of infants born in 1976, 1,161 infants were identified who were born to women coded as laboratory workers in the census. These infants were compared to all 98,354 infants born in Sweden in 1976. There was a higher than expected number of infants who died neonatally and/or had congenital malformations. Twenty-six singleton infants who either died or had serious malformations were selected for further study. To each of the cases, 2 controls were selected among the 1,161 infants. A questionnaire was sent to the 26 cases and 50 controls (2 cases had only 1 control each) asking about work during pregnancy. No specific type of laboratory work was found to be more common among the cases than controls.

Initiation of breastfeeding.

UNLABELLED: Breastfeeding is a biological process that is highly influenced by various physiological and environmental factors such as the plans for infant feeding of pregnant women, their education and work situation, family support and nutrition. CONCLUSION: The way in which breastfeeding is initiated in the early postnatal period is of importance both for how long the process is likely to continue and for the growth of the infant.

Trends in research on infant nutrition, past, present and future.

A review of general trends in early infant feeding is presented, with particular focus on the importance of breast feeding. That the promotion of breast feeding is highly effective is borne out by the tendency toward its prevalence in Sweden during the period 1972-94.

Child health and environmental pollution in the Aral Sea region in Kazakhstan.

Environmental pollutants, which may occur in breast milk and in various food products and drinking water, and which are also transferred to the foetus, constitute a severe threat to the health of infants and children. Among such compounds, various organochlorines, such as pesticides for the control of parasites (DDTs, HCHs), and products of industry and agriculture, such as dioxins and dioxin-like compounds (PCBs), are much discussed, in addition to organic mercury and heavy metals, such as lead and cadmium. The consequences of acute exposure to PCB have been documented in Japan following the ingestion of rice oil contaminated by PCBs. In Sweden birthweight has been found to be reduced and the perinatal mortality rate higher than expected in regions with high consumption of fatty fish from the Baltic Sea. In addition, from studies around Lake Michigan, it has been shown that children who have been exposed to PCBs in utero have retarded cognitive development. In the Aral Sea basin in Central Asia people have been subjected to long-term exposure to various pesticides, which have been distributed over the cotton fields in huge quantities. Organochlorines are resistant to breakdown in nature, thus they enter the food chain, eventually entering the human diet, and they may also be inhaled from dust. Such compounds accumulate in the foetus by placental transport and continue to do so postnatally if the infants are breastfed, as they may be present in high concentrations in human milk. The health of children living in the Aral Sea region is reported to be poor, with high morbidity and mortality and a high rate of chronic diseases and retarded mental and physical development. However, in addition to being subjected to environmental pollution, these children also suffer from health hazards related to poverty. Through epidemiological studies it may be possible to obtain information about to what extent exposure to environmental pollution from organochlorines contributes to the poor health of people living in the Aral Sea region.

Breastfeeding and infant-mother interaction.

The prevalence of breastfeeding varies very much throughout the world. In some countries, such as in Scandinavia, it is extremely high, whereas it is rather low in many industrialized countries such as northern Italy. In urban areas of many developing countries the prevalence is extremely low, although it may be high in rural areas. For instance, in rural Guinea-Bissau in West Africa it is reported to be 100% at 3 mo of age, and this high prevalence may be explained by the fact that infants who have not been breastfed die before this age. In Sweden the prevalence at 2 mo of age was around 95% in 1945 (including infants fed by milk-mothers) but then gradually dropped until 1972, when it was as low as 20%. However, during the following 10-y period the prevalence gradually increased to around 80%. The main reasons for the decline most probably were that infant formulae, then considered to be safe, became available, that an increasing number of women started to work outside their homes, making formula feeding part of the feminist movement, and finally that no real attempts were made to promote breastfeeding in the maternity wards and well-baby clinics. The reverse trend started in 1972, when the attitude towards breastfeeding changed completely. Well-educated mothers became aware of the new discoveries of the importance of breastfeeding from immunological and nutritional points of view, and organized campaigns. Within a few years, the Swedish parliament passed a law which guaranteed all mothers paid leave from their work (80% of their salary) for 9 mo after childbirth, which has now been increased to 12 mo. The WHO/UNICEF code from 1980, which regulates the marketing of infant formula, has also probably played an important role. After a plateau for the prevalence of breastfeeding between 1982 and 1990, a further increase has taken place, particularly between 6 and 9 mo of age. Whereas the first phase in the increase of the prevalence of breastfeeding was, to a certain extent, the result of the concern of well-educated mothers, the second phase (1990-1998) may, at least partly, be explained by the fact that Swedish maternity wards then implemented the suggestion, launched by WHO/UNICEF, to create "baby-friendly" maternity hospitals with the aim of enabling all women to practise exclusive breastfeeding immediately after birth. Methods to stimulate lactation and proper nutritional suckling behaviour of the newborn were then developed.

Sodium, potassium and chloride needs in low-birth-weight infants.

A review of the daily requirements of sodium, potassium and chloride in preterm infants with particular emphasis on very low-birth-weight (VLBW) infants is given against the background of our present knowledge of the homeostatic regulation of these electrolytes during early postnatal life. Particular attention has been given to the importance of balanced fluid and electrolyte homeostasis in the control of compartment volumes and tonicity. The risk of rapid changes of extracellular fluid osmolality for many organs, and particularly for the brain, has been stressed. In order to obtain an adequate sodium and fluid balance during the first postnatal weeks in preterm infants of varying gestational age, recommendations for sodium intake during the first 4-5 postnatal weeks are given.

Amphetamine addiction during pregnancy: 10-year follow-up.

Sixty-five children born to women who all used amphetamine during pregnancy have been followed prospectively since birth 1976-77. They have been tested and examined at one, 4 and 8 years of age. In addition, information about the school situation was collected after 10 years. Twenty percent of the children were put in foster homes at birth, and after 10 years 70% were in foster homes. The children showed a normal intellectual capacity. However, at 10 years of age 8 children (12%) attended one class below what was normal for their biological age (normal in Sweden < 5%). At 4 years of age 35% had an aggressive behaviour and at 8 years 23%. There was a statistically significant correlation between aggressive behaviour and amphetamine exposure during fetal life. At both 4 and 8 years of age 40% were considered to have a poor adjustment, which correlated with socio-environmental factors. Lower values for weight and length also showed a correlation with socio-environmental factors. The study shows that amphetamine abuse during pregnancy will influence development of exposed children at least up to the age of 10 years.