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Biomedical subjects

P M Slack

Publications and source records attributed to P M Slack.

11 recordsLinked to original sources
PubMed1987

Mannosidosis: ocular lesions in the bovine model.

The ocular pathology of mannosidosis was studied in the bovine model. There was wide-spread vacuolation of many cell types including corneal epithelium, Descemet's endothelium, corneal fibroblasts, pigmented cells, lens epithelium, lens fibres, pigment epithelium and all cell types of the neuroretina. On electron-microscopy most vacuoles were seen to be membrane bound vesicles compatible with being secondary lysosomes and similar to those previously described elsewhere in the body. Additional vacuoles were seen due to dilatations between lens epithelial cells and between lens fibres. The cause of lens and corneal opacities seen in human patients is unclear from the present study but are presumably a consequence of the lesions noted.

Animals↗
PubMed1986

The nature of thyrotropin stimulation of thyroid function in Japanese quail: prolonged thyrotropin exposure is necessary to increase thyroidal 125I uptake.

Single injections of thyrotropin (TSH) increase serum T4 and thyroidal 32P uptake but not thyroidal 125I uptake regardless of dosage, exposure time or age. Chronic TSH exposure, with 3 or more days of injection, does increase thyroidal 125I uptake. Studies using iodine (I) supplementation indicated that the increased thyroidal radioiodine uptakes seen with chronic TSH administration were not due to an I deficiency in the thyroid resulting from high hormone release. Labeled and unlabeled experiments comparing the effects of single vs. multiple injections of TSH were used to describe the effects of TSH on hormone release, hormone production and thyroidal I uptake.

Animals↗
PubMed1980

Mannosidosis: patterns of storage and urinary excretion of oligosaccharides in the bovine model.

Mannose and glucosamine-containing oligosaccharides were extracted from tissues of variously aged calves with mannosidosis. Whereas storage in the brain, and to a lesser extent in the pancreas and lymph nodes, was cumulative, that in the liver was relatively stable over the time period followed. It is suggested that in this latter organ the 15--20% residual alpha-mannosidase activity attributable to the mutant enzyme might be sufficient to normalise function. In the kidney, levels actually fell over the first 15--20 weeks of life and thereafter remained constant. It is postulated that, in foetal life, storage is cumulative but, after birth, storage material is lost from the kidney into the urine by degeneration and/or desquamation of renal tubular cells. From 20 weeks the amount lost is in equilibrium with that formed or absorbed by the tubular cells.

Animals↗
PubMed1975

Morphological and virological investigations of cell strains cultured from the brain in Jakob-Creutzfeldt disease and subacute sclerosing panencephalitis.

Cell strains were established in culture from fragments of the brain from 2 cases each of Jakob-Creutzfeldt (JC) disease and subacute sclerosing panencephalitis (SSPE). After about 12 weeks strains from the former spontaneously formed persistent heaped up nodules of cells which appeared to produce reticulin-like fibrils as well as confluent sheets of rounded and spindle, fibroblast-like cells. Similar sheets of cells were obtained from the cases of SSPE but the only nodules formed were smaller and ephemeral. Attempts to detect virus in all 4 strains were made by inoculation of supernatant fluids into cultures of other laboratory cells, haemadsorption, co-cultivation, electron microscopy and immunofluorescence, and testing for interferon production. No evidence was found by any of these methods of the persistent presence of virus in the strains. Immunofluorescence revealed a probable anti-glial cell IgM autoantibody in one case of JC disease. Morphologically some cells resembled astrocytes and others fibroblasts. Those from JC disease contained more vacuoles and redundant membranes than did those from the cases of SSPE, features that are particularly striking in brain cells in human and animal cases of the spongiform encephalopathies.

Autoantibodies↗
PubMedDate not supplied

Ceroid-lipofuscinosis (Batten's disease): pathogenesis of blindness in the ovine model.

Blindness is a feature of the group of storage diseases of children known as the ceroid-lipofuscinoses. Sequential studies in the ovine model, which most resembles the juvenile form of human disease, showed clearly that blindness had two components, a central and a peripheral. Whereas the central component, attributable to neuronal death and atrophy of the cerebral cortex, was responsible for early loss of vision, retinal atrophy was also extremely advanced in terminal stages of the disease. The primary retinal change was one of dystrophy of photoreceptor outer segments which preceded degeneration and necrosis of the photoreceptors cells themselves. Electroretinography showed that there was a progressive loss of a- and b-waves during the course of the disease, but this was preceded by a diminished c-wave which was eventually replaced by a negative potential. However, the pigment epithelium remained functionally (azide responsive) and ultrastructurally intact throughout the study. Loss of brain weight with selective cerebral atrophy also correlated with abnormal behaviour and facial manoeuvres that were interpreted as partial seizures that did not become generalized.

Animals↗
PubMedDate not supplied

Ceroid-lipofuscinosis (Batten's disease): pathogenesis and sequential neuropathological changes in the ovine model.

A sequential morphological study of ovine ceroid-lipofuscinosis showed that brains of affected lambs were normal at birth, grew until four months of age but then atrophied. Laminar necrosis of cerebral cortex was noted at 10 weeks, occurring first in the parietal area, then spreading to involve frontal and occipital areas while the temporal lobe was least and last affected. With progression of the disease, the laminar pattern was lost. Neuronal necrosis was accompanied by a severe astrocytosis. The granular and multilamellar storage cytosomes increased in size with age. Their structure was interpreted as paracrystalline in which repeating molecules of the dominantly stored lipid binding subunit of mitochondrial ATP synthase interact with neutral lipids and phospholipids. Abnormal cytosomes in neurons of lamb fetuses and a neonate were interpreted as early lesions which contained whorls or stacks of bilayered membrane as well as the more complex multilamellar material. The underlying anomaly leading to the storage of the lipid binding subunit of mitochondrial ATPsynthase remains to be defined. However, it is noted that this disease should be regarded as a lipid binding protein proteinosis or alternatively as a proteolipid proteinosis.

Age Factors↗