Copper in fetal and neonatal development

The essentially of copper for normal fetal and neonatal development has been well documented, although copper metabolism during this period is poorly understood. The dietary requirement for copper is influenced by genetic background. The neurological phenotypic characteristics of the mutant gene quaking (qk) in mice resemble in part those of copper-deficient animals. Supplementation of the maternal diet with copper during pregnancy and lactation, or during lactation alone, greatly reduced the frequency of tremors characteristic of these mutants, and brought the otherwise low copper concentrations in the brain to normal. Prenatal copper supplementation of crinkled (cr) mice increased neonatal survival and produced nearly normal development of skin and hair. Non-supplemented cr/cr mice showed anaemia at 21 days of age which disappeared later. Similarly, copper concentration in liver and hair was low in young but normal in old cr/cr mice. However, activity of copper--zinc-superoxide dismutase (Cu-ZnSOD) remained low even at 60 days of age. Copper supplementation brought both SOD activity and copper concentration of liver and hair to normal. The errors in copper metabolism produced by qk and cr appear to be expressed at different periods of development. The hypothesis that there are rapid changes in the metabolism of copper is supported by the observation that molecular distribution of copper in rat intestine changes drastically during the neonatal period.

Immunocytochemical localization of border disease virus in the spinal cord of fetal and newborn lambs

The peroxidase-antiperoxidase technique was used to determine the cellular localization of Border Disease (BD) virus in cryostat sections of fetal and newborn lamb spinal cord following experimental infection by maternal inoculation in early gestation. Viraemic fetuses and lambs with hypomyelinogenesis showed BD viral antigen in neurons, glia, ependymal cells, vascular endothelial cells and fibrocytes within the dura mater. Double immunolabelling demonstrated co-expression of BD viral antigen and glial fibrillary acidic protein (GFAP) or myelin basic protein (MBP) in both fetal and newborn lamb glia. In fetal lambs there was a pia-associated population of glia in which viral antigen was also co-expressed with GFAP or MBP. The results suggest that BD virus infects myelinating oligodendroglia, astroglia and probably also transitional cells and pluripotential glioblasts. The relationship between infection of specific cell types and hypomyelinogenesis was not resolved but infection of transitional cells and oligodendroglia may affect oligodendroglial function and permit morphologically inapparent perturbations leading to hypomyelinogenesis. A single nonviraemic lamb with a precolostral antibody titre to BD virus and cystic cerebral cavities but no hypomyelinogenesis showed BD viral antigen confined to glia of the spinal cord white matter. This suggests that oligodendroglia may require to be infected before a critical period in their development or factors additional to oligodendroglia infection are necessary for hypomyelinogenesis.

An immunohistochemical study of the topography and cellular localization of three neural proteins in the sheep nervous system

The peroxidase-anti-peroxidase (PAP) method was used to determine the topography and cellular localization of glial fibrillary acidic protein (GFAP), myelin basic protein (MBP) and carbonic anhydrase II (CAII) in the central nervous system (CNS), dorsal root ganglia and dorsal and ventral spinal nerve roots of the sheep. Parallel studies of mouse brain provided comparative data. Several fixatives were compared for their relative merits in preserving marker protein expression: GFAP was well preserved irrespective of the fixative employed; MBP was best preserved in formal sublimate and CAII was best preserved in Carnoy's fluid. In sheep, GFAP expression was seen in protoplasmic and fibrous astrocytes, Bergmann glial cells, a proportion of ependymal cells, amphicytes of spinal ganglia and in a proportion of presumed Schwann cells of dorsal and ventral spinal nerve roots. MBP expression was seen in mature and developing myelin sheaths of the central nervous system and in the cytoplasm of sparse myelinating oligodendroglia of the sub-cortical white matter of the cerebrum. CAII expression was seen in choroid plexus epithelium in all ages of sheep studied and, in a young lamb and an adult sheep, in glia and neuropil of ventral horn grey matter of the spinal cord and in the cytoplasm of white matter glia, presumed fibrous astrocytes, throughout the CNS. Compared with sheep brain, mouse brain showed the following differences in marker protein localization. GFAP was weakly expressed by protoplasmic astrocytes and not expressed in ependyma, oligodendroglia expressing intracytoplasmic MBP were frequent and widespread in neonatal mouse brain, CAII was expressed in myelin and oligodendroglia.(ABSTRACT TRUNCATED AT 250 WORDS)

Tremors in Samoyed pups with oligodendrocyte deficiencies and hypomyelination

Over a 3-year period a breeder of Samoyed dogs observed six litters in which one or more pups at 3 weeks of age showed generalized tremors and an inability to stand. One affected pup, a 5-week-old male, was referred for clinical and pathological evaluation. Gross and microscopic studies including immunocytochemical demonstration of myelin basic protein, revealed a lack of myelin throughout the central nervous system. Ultrastructural studies revealed that a total absence of normal myelin was associated with oligodendroglial deficiencies. Oligodendrocytes were immature in appearance, greatly reduced in number, and incapable of forming compact myelin. Astrocytosis and an increase in the third type of neuroglial cells were observed. The changes differed from those reported in other canine forms of hypomyelinogenesis and were compared with hypomyelinating diseases in other species. The findings suggested that this hypomyelination was the result of retarded gliogenesis.

Border disease of sheep: spinal cord morphometry

Semi-automated planimetry was used to determine cross-sectional areas of spinal grey and white matter by direct microscopy of paraffin sections of spinal cord from Border disease (BD) and normal lambs at segments C4, C8, T6 and L4. Spinal cord cross-sectional area was significantly reduced in cases of BD produced by either intramuscular or intranasal inoculation of ewes in the first half of pregnancy with Weybridge strains of BD virus. The reduction was apparent at all 4 levels and in both grey and white matter, though the white matter was the more severely affected. Spinal cord areas tended to be smaller in the progeny of ewes exposed earlier in gestation or to larger doses of virus, but these differences were not statistically significant.

Congenital infections with nonarbo togaviruses

The present review deals with the similarities and differences of selected aspects of prenatal pestivirus infections of domestic animals and congenital rubella of man. Hog cholera virus, bovine virus diarrhoea virus and border disease virus are antigenically closely related, but unrelated to rubella virus. The nonarbo togaviruses are capable of producing congenital infections resulting in a wide spectrum of abnormalities. The infected foetus can die in utero, in the neonatal period, or it may be born with teratogenic defects. In addition, apparently healthy progeny can be delivered that develop a late onset disease, months, or years after birth, or remain clinically normal for life. The ultimate outcome of a congenital infection is mainly determined by the stage of foetal development, at which infection occurs. Foetuses exposed to rubella virus raise an antibody response to the virus, whereas domestic animals frequently fail to respond immunologically to a congenital pestivirus infection. In congenital rubella the virus usually disappears from the host's body 1-2 years after birth. However, congenital pestivirus infections may be characterized by a lifelong and widespread persistence of virus in clinically healthy animals. Such animals are of significance in the epizootiology of bovine virus diarrhoea, border disease or hog cholera.

Chronological study of oligodendroglial alterations and myelination in quaking mice

Chronological morphological investigation was carried out in the spinal cord of quaking mice from day 3 to day 130. Numbers of myelinated fibres were far fewer in quaking mice at day 3 compared to controls. However, when the animals became older, myelination progressed and numbers of myelinated fibres increased although myelin sheaths remained far thinner than the size of axons. Many oligodendroglia during day 5 to 15 in quaking mice revealed prominent dilation and proliferation of smooth walled vesicles and cisterns but after 20 days, such changes were no longer observed. Tortuous bizarre oligodendroglial processes, aberrant myelination and myelin figures were very prominent around day 5--15, but such changes also gradually subsided. Density of glial cells during pre-myelination gliosis was similar in both quaking and control mice. However, glial cell population decreased far slower pace than controls when myelination progressed. Thus, glial cell density remained proportionally higher in quaking than controls although the density declined with age in both.