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Biomedical subjects

M Jeffrey

Publications and source records attributed to M Jeffrey.

At least 109 records · Page 6Linked to original sources
PubMed1991

Carbonic anhydrase II expression in fibrous astrocytes of the sheep.

Immunohistochemical expression of carbonic anhydrase isoenzyme II (CAII) was demonstrated in a population of fibrous astrocytes in a young lamb and an adult sheep. Such cells were identified by co-expression of CAII and glial fibrillary acidic protein, nuclear morphology and their contribution of glial fibrillary acidic protein reactive processes to the glial limitans. Similar cells were not identified in neonatal lambs. As in man and mouse, CAII was also expressed in choroid plexus epithelium occurring in neonate, young and adult sheep brain. In contrast, however, to man and mouse, CAII was not expressed in sheep oligodendrocytes.

Age Factors↗
PubMed1990

Dandy-Walker malformation in two calves.

Two calves with unusual malformations of the skull and brain are described. Both calves showed doming of the posterior skull due to enlargement of the posterior fossa and cyst-like dilatation of the fourth ventricle. The cystic dilatation of the fourth ventricle formed a meningocoele in one calf. Aplasia of the cerebellar vermis was present in both calves. One calf showed agenesis of the corpus callosum. These features are consistent with the Dandy-Walker malformation of man.

Animals↗
PubMed1990

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)

Age Factors↗
PubMed1990

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.

Animals↗
PubMed1989

A myopathy of sheep associated with sarcocystis infection and monensin administration.

An outbreak of muscle disease affected approximately 20 of 600 ewes in spring 1987 in south-east Scotland. The clinical signs were a flaccid paralysis of the hind limbs and in severe cases collapse. Serum creatine kinase and aspartate aminotransferase activities were increased. Clinically affected sheep had a mean reciprocal serum antibody titre in a sarcocystis immunofluorescence antibody test of 557 whereas 22 sheep from the same flock, sampled one year earlier, showed a mean reciprocal titre of only 51. Histologically a heavy infestation of sarcocysts, myodegeneration and a non-suppurative myositis centred on degenerating sarcocysts were observed in a wide range of skeletal muscles and myocardium from four affected sheep. Monensin sodium had been inadvertently included in the protein pellet used in the feed for one week before the onset of the disease.

Animal Feed↗
PubMed1989

Atypical rotavirus and villous epithelial cell syncytia in piglets.

Histopathological examination of small and large intestine from piglets with enteritis has shown the presence of epithelial multinucleate syncytia. Syncytia were associated with a specific type of atypical rotavirus infection, determined by electron microscopy and polyacrylamide gel electrophoresis analysis of viral RNA. The observations are consistent with similar previously described natural or experimental infections in other animals.

Animals↗
PubMed1989

Membrane-Associated Polypeptides Induced in Chlamydomonas by Limiting CO(2) Concentrations.

Chlamydomonas reinhardtii and other unicellular green algae have a high apparent affinity for CO(2), little O(2) inhibition of photosynthesis, and reduced photorespiration. These characteristics result from operation of a CO(2)-concentrating system. The CO(2)-concentrating system involves active inorganic carbon transport and is under environmental control. Cells grown at limiting CO(2) concentrations have inorganic carbon transport activity, but cells grown at 5% CO(2) do not. Four membrane-associated polypeptides (M(r) 19, 21, 35, and 36 kilodaltons) have been identified which either appear or increase in abundance during adaptation to limiting CO(2) concentrations. The appearance of two of the polypeptides occurs over roughly the same time course as the appearance of the CO(2)-concentrating system activity in response to CO(2) limitation.

Journal Article↗
PubMed1988

Immunocytochemistry of ovine sporozoan encephalitis and encephalomyelitis.

An indirect immunoperoxidase procedure was developed to detect Sarcocystis spp meronts in paraffin wax sections of infected ovine tissues. Ten rabbits seronegative to Sarcocystis spp and Toxoplasma gondii were injected intradermally or subcutaneously over 2 months with varying quantities (150 to 750 micrograms) of purified soluble cystozoite antigen derived from ovine heart microcysts. Serum from each rabbit was tested against paraffin wax preparations of S. ovicanis cysts, second generation S. ovicanis meronts and T. gondii cysts. Sera from three rabbits reacted with S. ovicanis meronts without any cross reaction to T. gondii antigens. Toxoplasma gondii and Sarcocystis spp-specific sera were used to identify the sporozoa in six cases of naturally-occurring ovine encephalitis or encephalomyelitis. Sarcocystosis was diagnosed in four lambs and toxoplasmosis in one lamb. The generic identity of the sporozoan in the sixth case was not established as meronts reacted with both Sarcocystis spp- and T. gondii-specific sera. The study demonstrates the value of the immunohistological technique of visualizing sparsely distributed meronts in naturally-infected tissues and shows that sporozoa of the genus Sarcocystis and T. gondii, and possibly also sporozoa the identity of which is as yet unclear, are associated with encephalitis of sheep in Britain.

Animals↗
PubMed1987

Congenital sporozoan encephalomyelitis in a calf.

Protozoan encephalomyelitis was diagnosed post mortem in a five-day-old Friesian calf which had shown nervous signs from birth. The lesion was a subacute necrotising multifocal encephalomyelitis associated with protozoan bodies (6 X 6 microns to 16 X 30 microns). Ultrastructurally these bodies corresponded to apicomplexan meronts composed of eight to 89 merozoites which reproduced by internal budding to form paired daughter cells (endodyogeny). The merozoites were indistinguishable from Toxoplasma gondii; they reacted weakly with anti-Sarcocystis species serum and did not cross react with anti-T gondii serum. The generic identity of the sporozoan was not established, but it is unlikely to have been either Sarcocystis species or T gondii.

Animals↗
PubMed1987

Variable nature of border disease on a single farm: clinical and pathological description of affected sheep.

The clinical, pathological and virological findings in cases of Border disease occurring on a farm were studied. Fourteen abnormal lambs approximately three months old were obtained and were necropsied within 18 months at death or slaughter. Another lamb born during the study to a persistently infected ewe was also examined. The findings of these 15 animals are presented in three groupings. The animals of group A were persistently viraemic and hypomyelinogenesis was present in two lambs at one and 14 weeks old. Systemic, chronic, multifocal inflammation including nephritis, myocarditis and pneumonitis was found in older sheep. Group B lambs were non-viraemic and the predominant necropsy finding was cystic cerebral cavitation of variable severity. Histological examination showed cerebellar dysplasia and in two animals the retinas also showed multifocal photoreceptor cell atrophy. Lambs in group C were also non-viraemic and although these failed to thrive, no consistent pathological changes were found. It is concluded that the dams of animals in group A were infected in early pregnancy while those of animals in groups B and C were infected at mid-gestation or later.

Animals↗
PubMed1987

Variable nature of border disease on a single farm: the infection status of affected sheep.

Study of the virological and serological status of abnormal sheep derived from a single outbreak of Border disease indicated a relationship between infection status and diverse pathological lesions. Persistent infection was associated with typical Border disease whereas an active, even exaggerated, serological response correlated with severe intracranial malformations which probably resulted from fetal infections occurring during the early stages of acquisition of immune responsiveness.

Animals↗
PubMed1986

Pestivirus fetopathogenicity in cattle: changing sequelae with fetal maturation.

The events which followed the introduction of a heifer into a dairy herd were consistent with the animal being persistently infected with bovine diarrhoea-mucosal disease virus. Obvious damage was limited to the progeny of cows which were in the first 168 days of gestation at that time. Only fetuses up to 81 days of gestation at the putative time of introduction of infection became persistently infected in calfhood and, although they exhibited body tremor, two such calves necropsied at three months of age lacked macroscopic or microscopic lesions in the central nervous system. In contrast calves which had been more advanced in gestation, at 146 and 153 days at the time of infection, had eliminated the infection and had lesions of cerebellar dysplasia and multifocal retinal atrophy.

Abortion, Septic↗
PubMed1985

Kyphosis in Jersey calves.

A condition of Jersey calves involving kyphosis and lordosis is described. Four calves originating from three farms, all the progeny of one bull, were necropsied. The only significant finding was a myopathy mainly affecting sublumbar muscles. The lesions were not consistent with white muscle disease or of any known myopathy affecting Jersey calves. It is likely that this condition represents a primary muscular dystrophy of genetic origin.

Animals↗