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Biomedical subjects

M G Reyes

Publications and source records attributed to M G Reyes.

At least 19 recordsLinked to original sources
PubMed1996

Histopathology of the substantia nigra in Alzheimer's disease.

Histopathologic examination of the pars compacta of the substantia nigra of 17 patients with Alzheimer's disease showed Lewy bodies in six, neurofibrillary tangles in another six and only histologic changes that did not differ from age-matched controls in five patients. Four of the six patients with nigral Lewy bodies showed severe loss of neural cell bodies, reactive astrocytosis, gliosis and neuromelanin in macrophages and in the neuropile. By contrast, the loss of neuronal cell bodies in our patients without nigral Lewy bodies regardless of whether or not they also had nigral neurofibrillary tangles was no greater than what we observed in our age-matched controls. Quantitative cell counts confirmed our histopathologic estimates of neuronal loss. Our study and the findings of others show that the substantia nigra is often abnormal in Alzheimer's disease and that the abnormalities are rarely severe without nigral Lewy bodies.

Aged↗
PubMed1994

The aging substantia nigra: quantitative histologic study.

In this study, we estimated the amount of neuronal neuromelanin in hematoxylin and eosin sections of the pars compacta of the substantia nigra in 69 autopsied subjects, 14 to 100 years old. The mean area of cellular neuromelanin showed a curvilinear increase from 103 microns2 at age 14, to 600 at age 67 before dropping off to 328 at age 100 (R2 = +0.51, p < 0.00001). By contrast, the areal fraction or area of neuromelanin relative to the area of neuronal cell bodies showed a linear increase with age (r = +0.84, p < 0.00001). The latter and an increase in the percent of neuromelanin pigmented neuronal cell bodies from 83% at age 14 to almost 100% at age 65 and older (R2 = +0.61, p < 0.00001) accounted for the increasing mean area of cellular neuromelanin. By contrast, a decrease in the mean area of neuronal cell bodies (r = -0.63, p < 0.00001) and a decrease in the number of profiles of neuronal cell bodies (r = -0.51, p < 0.0001) explained the decrease of mean area of cellular neuromelanin beyond 67. Our findings support the hypothesis that an overload of neuromelanin is neurotoxic and emphasize the importance of using age-matched controls in histopathologic studies of the substantia nigra.

Adolescent↗
PubMed1991

Nigral degeneration in acquired immune deficiency syndrome (AIDS).

Using stereological techniques we have estimated the volume density of melanin and counted the number of pigmented and non-pigmented neuronal cell bodies in the pars compacta of the substantia nigra of 12 autopsied patients with acquired immune deficiency syndrome (AIDS) who did not have inflammation or necrosis of the midbrain or clinical parkinsonism. The total number of neuronal cell bodies was 25% lower in AIDS (P less than 0.01) than in 12 age-matched controls, although the volume density of neuronal melanin did not differ from that of controls because the percentage of pigmented cell bodies was higher (P less than 0.01) and the cell bodies were more fully packed with melanin in AIDS. Also, the expected increase with age of the volume density of neuronal melanin (P less than 0.02) and the percentage of pigmented neurons (P less than 0.01) occurred in the controls but not in AIDS patients. Importantly, our histopathological examination showed unequivocal nigral degeneration with neuronal loss, small neuronal cell bodies packed with melanin, reactive astrocytosis and extra-cellular melanin in the AIDS patients but not in controls. Our study shows that a subclinical nigral degeneration is common in AIDS and could possibly explain the heightened susceptibility of some patients to drug-induced parkinsonism.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Imprints, smears, and frozen sections of brain tumors.

In this study, we compared the suitability and accuracy of imprints, smears, and frozen sections of suspected brain and spinal cord tumors of 150 patients. Eighty-six percent of the imprints, 91% of the smears, and 99% of the frozen sections were suitable for interpretation. Among the suitable preparations, 82% of the imprints, 92% of the smears, and 99% of the frozen sections agreed with our diagnosis on paraffin sections. Although frozen sections were clearly more accurate than imprints and smears, the latter two provided diagnoses in patients with acquired immunodeficiency syndrome where frozen sections were not done to avoid contaminating our cryostat and in a patient with an epidermoid cyst of the middle fossa that could not be adequately frozen sectioned. Our study shows that imprints and smears complement frozen sections in the intraoperative diagnosis of tumors of the central nervous system.

Biopsy↗
PubMed1990

Malignant lymphoma presenting as a chronic subdural hematoma.

A 56-year-old man had a right frontotemporoparietal craniotomy for evacuation of an encapsulated subdural hematoma that had reaccumulated after burr-hole decompression 6 weeks before. Histopathologic examination showed a malignant lymphoma in the subdural hematoma. Our patient shows that malignant lymphoma can rarely present as a chronic subdural hematoma.

Brain Neoplasms↗
PubMed1989

Subcortical cerebral infarctions in sickle cell trait.

At necropsy, two patients with sickle cell trait and progressive motor and visual deficits, lethargy and coma showed infarctions of the deep cerebral white matter and brain stem. The findings in these patients and another reported in the literature suggest that subcortical infarctions may be more common in sickle cell trait than has been recognised and should be suspected in any patient with sickle cell trait who presents with an unusual neurological illness.

Adult↗
PubMed1989

Neural defects in Jarcho-Levin syndrome.

Neuropathologic examination of two autopsied patients with Jarcho-Levin syndrome showed no pathologic changes in the brain, spinal cord, or nerve roots of one and diastematomyelia of the thoracolumbar spinal cord in the other. The abnormalities of the spinal cord in one of our patients and in another patient described in the literature establish neural defects as a component of the Jarcho-Levin syndrome.

Female↗
PubMed1989

Aneurysmal bone cyst of the thoracic spine: treatment by excision and segmental stabilization with Luque rods.

Preoperative radiological evaluation with magnetic resonance imaging and computed tomography was valuable in planning the surgical management of a destructive lesion of the posterior elements of the thoracic spine that was causing spinal cord compression in an 18-year-old woman. Preoperative recognition of bilateral involvement of the pedicles in addition to the laminae and spinous process led to use of prophylactic segmental stabilization of the spine with Luque rods after successful excision of an aneurysmal bone cyst. This case provides an example of the usefulness of computed tomographic scanning and magnetic resonance imaging in assessing the distribution and location of vertebral tumor and its potential effect on spinal stability. The efficacy of combining radical excision with stabilization for treatment of aneurysmal bone cysts of the spine is emphasized.

Adolescent↗