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Biomedical subjects

R W Leech

Publications and source records attributed to R W Leech.

At least 55 records · Page 3Linked to original sources
PubMed1985

Intracranial germ cell tumors: pathobiological and immunohistochemical aspects of 70 cases.

Seventy cases of histologically verified intracranial germ cell tumor were reviewed: 43 germinomas, 16 immature teratomas, seven mature teratomas, two embryonal carcinomas, one choriocarcinoma, and one yolk sac tumor. The male-to-female ratio was 2.6:1. The average age was 19 years in patients with germinoma, 11 years in patients with immature teratoma, and 17 years in patients with mature teratoma. Duration of symptoms averaged 19 months for germinoma, three months for immature teratoma, and 11 months for mature teratoma. Sixty-six lesions were located in the midline. Fifty-eight percent of the germinomas arose anterior to the pineal gland, whereas 29% of the immature and 14% of the mature teratomas were located anteriorly. The histologic appearance of the germinomas was indistinguishable from that of the usual testicular seminoma. The immature teratomas contained tissue from all three germ layers and exhibited morphologic features of fetal tissue. Of 14 immature teratomas, seven contained, in addition, foci of other malignant germ cell elements; thus, there were two teratocarcinomas, two lesions with germinoma and immature teratoma, two lesions with extensive rhabdomyoblastic differentiation in an immature teratoma, and one lesion with both germinoma and embryonal carcinoma in addition to immature teratoma. The seven mature teratomas consisted of fully differentiated epithelial and mesenchymal tissues. In 23 cases, immunoperoxidase stains for human chorionic gonadotropin (HCG), alpha-fetoprotein (AFP), and carcino-embryonic antigen (CEA) revealed patterns which, with minor exceptions, were essentially identical to those found in genital germ cell lesions. Survival was longest for patients with germinomas. In classifying germ cell tumors of the central nervous system, the World Health Organization's (WHO) classification of testicular germ cell tumors is preferable to its present classification of intracranial germ cell tumors.

Adolescent↗
PubMed1984

The mode of action of ethyl lactate as a treatment for acne.

We have shown that an alcoholic lotion containing ethyl lactate when applied topically to rat skin under occlusion became localized in the follicles and sebaceous glands. When applied to human facial skin the ethyl lactate was hydrolysed to ethanol and lactic acid, and thereby lowered the skin pH. Under such conditions the growth of recoverable skin bacteria, in particular the anaerobe Propionibacterium acnes, was inhibited, and the hydrolysis of sebum to free fatty acids by lipase derived from the bacteria was greatly impaired. These effects of ethyl lactate would account for its observed clinical efficacy in acne vulgaris.

Acne Vulgaris↗
PubMed1982

Colloid cyst of the third ventricle. A scanning and transmission electron microscopic study.

Three colloid cysts of the third ventricle were examined by both transmission (TEM) and scanning electron microscopy (SEM). There was morphological diversity of the cyst surface on SEM, with ciliated and non-ciliated cells present. In some areas, the non-ciliated cells were more numerous and extended above the surface. Individual non-ciliated cells show a wrinkled cell surface and bleb-like structures. The TEM findings correlated well with SEM, revealing two cell types. The non-ciliated cells appeared to have both exocrine and apocrine activity. In ciliated cells, abnormal cilia were related to abnormal centrioles; also present were highly abnormal microvilli. The appearance of the surface was similar to a normal ventricular surface. By allowing a greater assessment of cell types and their distribution, SEM has added one additional dimension in the evaluation of colloid cysts and their possible derivation.

Adult↗
PubMed1981

A family affected with intestinal polyposis and gliomas.

The third affected family with Turcot syndrome is presented and the problems associated with the occurrence of familial aggregates of cancer are discussed. Turcot syndrome represents the unique and discrete occurrence of polyposis coli with glioblastoma multiforme, medulloblastoma, or both.

Adolescent↗
PubMed1979

Neuropathologic features of idiopathic respiratory distress syndrome.

Evaluation of the neuropathologic alterations occurring in 170 consecutive autopsies in premature infants dying of the idiopathic respiratory distress syndrome (IRDS) reveals two large groups, hemorrhagic and nonhemorrhagic. Hemorrhages occurred in all possible sites and formed the single largest group. Such hemorrhages appeared to be related to the early death of many premature infants. The nonhemorrhagic group was quite variable, with the largest category of associated lesions being periventricular leukomalacia, the frequency of which increased with increasing age. We suggest that the nonhemorrhagic group may be an important factor in the morbidity of survivors.

Autopsy↗
PubMed1978

The neuropathology of the nonketotic and ketotic hyperglycinemias: three cases.

Abnormal dysmyelination constitutes a pathoanatomic basis for the mental retardation in two different aminoacidopathies, nonketotic hyperglycinemia and ketotic hyperglycinemia. In both conditions myelin is decreased in amount and vacuolated. Similar patterns of dysmyelination in different aminoacidopathies suggest that abnormal myelination results from inadequate synthesis of myelin proteins.

Amino Acid Metabolism, Inborn Errors↗
PubMed1978

Intrathoracic meningocele and vertebral anomalies in a case of neurofibromatosis.

A case of an intrathoracic meningocele associated with vertebral scalloping, enlarged intervertebral foramina and scoliosis in neurofibromatosis without spinal or nerve root rumors is described. A markedly attenuated dura mater anteriorly was present at autopsy and may have predisposed to meningeal herniation and scalloping.

Adult↗
PubMed1977

Anoxic-ischemic encephalopathy in the human neonatal period. The significance of brain stem involvement.

Although the human brain stem is considered relatively invulnerable to ischemic anoxia, evaluation of 16 cases of a single acute asphyxial episode either at or following birth indicates that such involvement is a frequent and characteristic aspect of anoxic encephalopathy in the infant. Ischemic cell change, neuronal loss, and nuclear or reticular formation gliosis were present in the brain stem of all but one infant. At least two topographic patterns of anoxic encephalopathy exist: (1) a rostrocaudal pattern of decreasing vulnerability, with the cerebral cortex being most sensitive and the brain stem least sensitive, and (2) a pattern of brain stem and thalamic damage. Of the two, the latter pattern appears to follow most acute asphyxial episodes in the human neonate and infant.

Adolescent↗
PubMed1977

Epithelial cysts of the neuraxis: presentation of three cases and a review of the origins and classification.

Benign, epithelial-lined cysts of the neuraxis may be asymptomatic or may behave as space-occupying lesions. Presentation of three such cysts, including an intramedullary epidermoid cyst, a lumbosacral subcutaneous enteric cyst that has an epithelium resembling ependyma, and a hypophyseal duct cyst, illustrates typical problems encountered. Review of their histogenesis and possible embryogenesis indicates that intracranial ependymal cysts and cysts of the sella turcica are not normally associated with other anomalies and frequently occur after middle age, whereas dermal and enteric cysts occur within the first two decades and are commonly associated with vertebral anomalies and other dysraphic syndromes. Enteric cysts may have a variable histologic appearance, including one resembling ependymal cysts. Recognition of the latter is important because of a possible associated dysraphic syndrome and the presence of an extraneuraxial component with the former but not the latter.

Adult↗
PubMed1977

Bovine hydrocephalus in North Dakota: a survey and morphologic study.

A survey of hydrocephalus in cattle in North Dakota in 1975 and 1976 included 26 proven cases falling into categories comparable to that seen in the human situation. The largest group was hydrocephalus secondary to aqueductal stenosis with the second largest group being hydranencephaly. Other groups included the Dandy-Walker malformation, porencephaly and a miscellaneous group having a variety of central nervous system malformations. All cases were sporadic with no evidence to suggest a genetic basis. The similarity suggests that calves could serve as a useful model for the human situation.

Animals↗
PubMed1975

Neurotoxicity of topically applied hexachlorophene in the young rat.

Young rats 6 to 22 days of age are extremely susceptible to the neurotoxic effects of hexachlorophene given as a daily bath of undiluted antiseptic detergent containing 3% hexachlorophene (pHiso-Hex). At this age, most rats are clinically and histologically damaged by as few as two daily baths. Younger rats are relatively resistant, probably because they have less myelin to be affected; older rats cannot be poisoned by this route, probably because the more mature liver excretes the drug more effectively. Age-dose-response curves in rats are similar to those in humans. This experimental model is potentially useful in defining other characteristics of this drug.

Administration, Topical↗
PubMed1975

Neurotoxicity of hexachlorophene in humans. II. A clinicopathological study of 46 premature infants.

To assess neurotoxic effects of hexachlorophene in the human population previously shown to be most at risk, a blind clinicopathological analysis was made of all premature infants under 1,400 gm birth weight who survived at least four days and were examined by autopsy over a 7.5-year period. Repeated whole-body bathing of premature newborn infants in 3% hexachlorophene-bearing soap (undiluted pHisoHex) shows a significant statistical association with a vacuolar encephalopathy of the brain stem reticular formation. The prevalence of the vacuolar encephalopathy in premature infants on whom we have adequate brain stem histological information appears to be related to the number of exposures to hexachlorophene, the concentration of hexachlorophene, the thoroughness of rinsing, and other factors (including exposure to ultraviolet light).

Administration, Topical↗
PubMed1975

The biology of childhood ependymomas.

The biology of 74 childhood ependymomas has been retrospectively investigated in total population samples from three hospitals in two cities. Regardless of the tumor's site of origin, the prognosis is grim. No child has been cured by surgery alone. The symptom-free interval after surgery is a first-order function of the age at diagnosis. The criteria for cure are best approximated by Collins "law," in terms of which there are apparently only three cured patients in this study. Intracranial ependymomas are best treated by careful excision of the tumor and radiation of a generous area to a total dose of at least 4,500 rads over a 60-day period. Radiation of the entire neuraxis appears to be indicated only in those few cases that can be considered malignant microscopically.

Adolescent↗