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Biomedical subjects

H M Liu

Publications and source records attributed to H M Liu.

At least 163 records · Page 9Linked to original sources
PubMed1978

Congenital central hypoventilation syndrome: a pathologic study of the neuromuscular system.

An infant with congenital central hypoventilation was managed by bilateral phrenic nerve pacing for 3 months. He died at 8 months of age, following 19 days of continuous bilateral pacing necessitated by the eventual loss of voluntary as well as autonomic ventilatory control. The phrenic nerves showed axonal dystrophy at the site of electrode implantation and more severe distal degeneration. Focal neurogenic atrophy was seen in the diaphragmatic muscle. These changes were attributed to electrical injury resulting from the period of continuous pacing. The most significant neuropathologic finding was a mild generalized decrease in the density of neurons and myelinated nerve fibers in the respiratory centers of the medulla. These morphologic abnormalities were attributed to a sublethal intrauterine lesion that would be the first example of a morphologic correlation with the functional abnormality in congenital central hypoventilation.

Brain↗
PubMed1977

Neuraxonal dystrophy of the brain in patients receiving antineoplastic chemotherapy.

The present report describes the neuropathological change found in the brainstem of four patients who were treated with combined chemotherapy for various types of malignant disease. The change consists of localized axonal swellings, the so-called "axonal spheroids" located predominantly in the medial lemniscus, the fibers from the olivary nuclei and around some of the cranial nerve nuclei. In addition to the brain change, all four patients had shown histological evidence of hepatic injury, although none of the patients exhibited overt clinical or chemical evidence of hepatic insufficiency. Neither did these patients show any clinical neurological deficit that could be related to the pathological findings. The neuroaxonal changes are most likely the result of altered metabolism as a consequence of the chemotherapy.

Adolescent↗
PubMed1977

Ependymomas of childhood. II. Electron-microscopic study.

Electron-microscopic study of various histological types of ependymoma has shown three basic types of cells. One type of cells has features typical of normal ependymal cells, the second type consists of cells resembling normal or reactive astrocytes, and the third type of cells is undifferentiated. The three types of cells are present in various proportions in every tumor. Generally speaking, the astrocyte-like cells are more frequently encountered than the ependymol cells. The undifferentiated cells are seen, in small numbers, in all forms of ependymoma but they are the dominant cell type in the ependymoblastomas.

Astrocytoma↗
PubMed1976

Neuropathological considerations in cerebro-hepato-renal syndrome (Zellweger's syndrome).

The nervous system in patients with cerebro-hepato-renal syndrome appeared to be affected at various tissue levels. There was evidence of a migrational disorder manifested by polymicrogyria and lack of normal neuronal maturation. There was dysmyelination of the white matter associated with accumulation of neutral fat in astrocytes. Within the peripheral nerves, masses of tangled neurofilaments producing dystrophic axons were demonstrated by electron microscopy. These findings could be explained on the basis of a genetic metabolic defect, one that involved particularly the amino acids. The defect may have interfered with the normal intercellular reaction during embryogenesis resulting in the malformation of multiple organs. The same metabolic abnormality could have caused the hepatic damage and disturbance in normal myelination during the neonatal period.

Abnormalities, Multiple↗
PubMed1976

Progressive spastic paraparesis and adrenal insufficiency.

A 10-year-old boy with progressive paraparesis, personality change, and seizures had laboratory evidence of adrenal insufficiency. Pathologic study showed cerebral edema, but no loss of myelin. Notable pathologic changes were limited to the spinal cord, where the corticospinal and spinocerebellar tracts were demyelinated. Lipid analysis of the brain was normal apart from the finding that galactocerebroside contained a higher proportion than normal of alpha-hydroxy fatty acids. We suggest that this case represents a distinct disease, differing importantly from adrenoleukodystrophy. The underlying defect appears to be in the early enzymatic pathway before cholesterol synthesis, although it is also possible that the defect is at the cell membrane.

Adrenal Insufficiency↗
PubMed1976

An ultrastructural study of the effects of x-irradiation on the oral epithelium of the rat: qualitative aspects.

Adult male rats of Simonsen strain were given a dose of 5000 r at 50 peak KV of x-irradiation directed at the lower lip, which was everted through a hole in a lead rubber cylinder shielding the head and body of the animal. Light and electron microscopic observations were made on specimens of lip oral mucosa from animals killed at 2, 6, 26 and 50 h and at 12 days after irradiation. The experimental model met the aim of permitting the study of the sequential effects of high dose of irradiation without causing ulceration of the mucosa. Widespread degenerative changes were noted in the basal cells as early as 2 h after x-irradiation, increasing in degree up to 50 h. They included inflation of the outer nuclear envelope and rough endoplasmic reticulum (RER) with loss of ribosomes, swelling of mitochondria and disarrangement of cristae evident at 2 h, followed at 6 h by swelling of nucleus and cytoplasm and 26 h by frank membrane breaks. Irreversible degrees of damage were noted in a small though growing minority of cells. Immediate mobilization of the Golgi-lysosomal system was evident as an increase in size of the zone, maximal at 2 h, and subsequent autophagic activity. Signs of recovery, beginning at 26 h, were noted in nuclear envelope, RER, intercellular space, and in mitotic activity by 50 h. Virtually complete recovery was seen at 12 days. It is held that the successful confinement of irradiation to a small tissue volume, the effective activity of the lysosomal system and the short epithelial turnover time were important factors in limiting the damage and in permitting recovery.

Animals↗
PubMed1976

Ependymomas of childhood. I. Histological survey and clinicopathological correlation.

We have conducted a correlative histological and clinical study on 34 cases of childhood ependymomas encountered at the Children's Memorial Hospital from 1953 to 1974. The cases were classified into grades A, B and C according to the extent of cytological differentiation and the correlation between the histological grades and the clinical outcome was obtained. It is concluded that the biological behavior of an ependymoma could be predicted to a large extent by the degree of cytological differentiation and by its anatomical location. A large share of the infratentorial ependymomas are well differentiated (grade A) and prognosis in this group is good when complete surgical removal could be accomplished. Most of the supratentorial ependymomas belong to the intermediate grade B and the malignant grade C; prognosis in these two grades is less predictable, approximately two thirds of these patients died within 3 years. The most malignant form is the ependymoblastoma. This is a highly primitive neoplasm histologically similar to medulloblastoma but shows evidence of ependymal differentiation. Most of the ependymoblastomas are located in the supratentorial region and the average length of survival is 20 months.

Adolescent↗
PubMed1974

Schwann cell properties. II. The identity of phagocytes in the degenerating nerve.

The present study was undertaken to identify the cells from which phagocytes originate following traumatic injury to the sciatic nerves in rats. The morphologic evolution of the phagocytes was correlated daily with changes in axon, myelin, Schwann cell and neurilemmal tube at light and electron microscopic levels. Autoradiography with tritiated thymidine was employed to label the proliferative cells immediately before and following the injury. The result indicated that degeneration of Schwann cells occurred with the onset of myelin breakdown and that the degenerated products of myelin, axon and Schwann cells were removed by macrophages. While most of the macrophages were originally blood monocytes, some were derived from vascular pericytes. They penetrated the neurilemmal tubes on the third postoperative day and began engulfing first the Schwann cells and then the myelin and axons. Having filled their cytoplasm with debris, some macrophages moved out of the neurilemmal tube while others remained temporarily inside the envelopes formed by the persisting neurilemmal tubes-thus the macrophages can inherit a basal lamina from degenerated Schwann cells.

Animals↗