Skeletal muscle pathology in AIDS: an autopsy study

A survey of skeletal muscle pathology in 92 autopsied cases of AIDS revealed microscopic alterations in 64 cases. There were 40 cases of disuse atrophy, 8 of denervation atrophy, 2 of cryptococcal myositis, 1 of Mycobacterium avium intracellulare (MAI) infection and 2 of necrotizing myopathy associated with hyperkalemia. A second group of cases with changes of unknown etiology was found. These were tentatively ascribed to the direct or indirect action of HIV. This category includes 8 cases of inflammatory myopathy, 8 of necrotizing myopathy in absence of a known etiological factor, 3 of extreme atrophy and 4 of "regenerating" myopathy.

Prevention of myelinolysis in rats by dexamethasone or colchicine

The purpose of the present investigation was to determine whether dexamethasone, an agent known to preserve the blood-brain barrier, and colchicine, an agent that impairs mobilization of macrophages, can prevent demyelinating lesions associated with rapid correction of hyponatremia in the experimental animal. Hyponatremia was induced in rats with Pitressin and water. After 4 days hyponatremic rats received hypertonic saline alone or hypertonic saline plus dexamethasone or colchicine. All of the 9 rats that received only 5% NaCl developed demyelinating disease, while 3 of 6 rats treated with dexamethasone and 5 of 15 rats treated with colchicine showed no CNS abnormality. The results of our investigation might help understand the pathogenetic mechanism of central pontine myelinolysis in humans, a disease attributed to rapid correction of hyponatremia.

Medullomyoblastoma in an adult

Medullomyoblastoma is a rare histologic variant of medulloblastoma. Of the 20 cases reported in the literature, 19 were in children ages 2.5 to 10.5 years and one was in a 26-year-old woman. In the reported adult case the myogenic component of the tumor was leiomyosarcomatous. The authors report a case of medullomyoblastoma with a rhabdomyosarcomatous component in a 40-year-old man with light microscopic, immunohistochemical, and ultrastructural findings. The histogenetic theories regarding this tumor include that it is a teratoma, or that the myogenic component arises from the perivascular or leptomeningeal ectomesenchyme, or pluripotential neuroectodermal cells, or endothelial cells. The authors' findings do not elucidate the histogenesis but argue against an endothelial origin of the rhabdomyoblastic component.

A semi-Markovian model for predator-prey interactions

In the study of population dynamics, the predator-prey system is recognized as a vitally important aspect in natural population control. On aspect of predator-prey interactions is studied in this paper. The attack cycle of a predator is assumed to consist of four different activities, namely, search, pursuit, handle and eat, and digestion. A semi-Markovian model is proposed to obtain the number of prey devoured by a predator during the activity of a day. The advantages of a new semi-Markovian model to the queueing model developed by Curry and DeMichele (1977) is demonstrated, as the results from the semi-Markovian model are closer to Holling's (1966) experimental data than their results, which were based entirely on Poisson assumptions.

Correlation of light and scanning electron microscopy a new method for exfoliative cytology

A method for preparing locator slides for light and scanning electron microscopy has been developed. These slides make possible correlation of light and scanning electron microscopy of individual cells. Some examples of the value of this method are given.