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Possible age-related changes in the nerve cell population of the inferior olive were studied through densitometric analysis. The mean area per nerve cell, the reciprocal of the number of cells per unit area, was derived from the distance to closest neighbor in an unselected autopsy series of specimens from 26 subjects without signs of neurological damage, aged 24 to 83 years. Kendall's rank method showed correlation between the mean area per nerve cell and the subjects' ages, with mean areal values decreasing with age. The increase in neuronal density with age was related to changes occurring in the neuropil of the adult. These changes consist of regression of olivocerebellar contacts and loss of supernumerary axonal collaterals, with a resulting decrease in the volume of the whole formation. In addition, the data supported the hypothesis that the nerve cell population of the inferior olive should not decrease with aging.

Lesions of the central nervous system were seen in 13/22 autopsies of Italian subjects affected by the acquired immune deficiency syndrome and including 19 intravenous drug addicts. Multinucleated cells similar to those originally described by Sharer et al. [1985] in response to direct central nervous system lesions by the human immune deficiency virus were seen in five subjects. Isolated or multiple opportunistic infections of the brain including cerebral toxoplasmosis (7 cases), progressive multifocal leukoencephalopathy (4), cytomegalovirus encephalitis (3), and tuberculous meningoencephalitis (2) were recognized. Finally, three cases of primitive cerebral lymphoma of large round cells were found. The central nervous system is a target, like the lymphoid tissue, of direct damage for the human immune deficiency virus, and it is frequently affected by opportunistic infections due to the immunological impairment sustained by the acquired immune deficiency syndrome.

Pathologic findings in 25 autopsies of AIDS. The common and severe changes of the central nervous system, lungs, adrenals, heart, kidneys and gonads are reviewed in a series of autopsies of AIDS. In the brain, HIV infection induces directly inflammatory infiltrates including the typical multinucleated giant cells described by Sharer. In addition, primary lymphomas are seen as well as reactive and inflammatory lesions that are caused by opportunistic infections, such as those of poliomavirus, Cytomegalovirus and Toxoplasma gondii. In the lung, interstitial inflammation prevails, which may be related to direct HIV infection and include rare multinucleated giant cells like the ones described by Sharer. Opportunistic infections are often associated, and are commonly sustained by Cytomegalovirus and Pneumocystis carinii. A peculiar findings is the evolution from septal inflammation to fine fibrosis and hyaline degeneration, either focal or diffuse. We believe that the severe respiratory insufficiency that is commonly seen in the advanced stages of AIDS could be related to the interstitial damage. In the adrenal gland, the most common change is Cytomegalovirus infection affecting both the cortex and the medulla, and inducing massive necrosis in the cortex with little or no reaction. Again, adrenal involvement should be related to adrenal functional insufficiency, which may be over-looked clinically because of the preponderant lesions of other sites. In the heart, myocarditis is often discrete, and may be complicated by perivascular fibrosis and rare foci of myocytolysis; in some cases primary lymphomas may also develop. In the kidney, several histological lesions are found, including glomerular damage with segmental necrosis, cortical areas of hyporeactive necrosis, and mild interstitial inflammation. In the gonads, the changes are partly induced by drug abuse, and consist of atrophy with secondary hypoplasia of the germ cells and interstitial fibrosis. In conclusion, the most important abnormalities consist of opportunistic infections, hyporeactive necrosis, fibrotic evolution of the inflammatory infiltrates and neoplasias (Kaposi's sarcoma and lymphomas). In this work, the changes of the lymphoid organs are only mentioned, for they have been widely reviewed elsewhere.