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Biomedical subjects

R W Alexander

Publications and source records attributed to R W Alexander.

At least 235 records · Page 13Linked to original sources
PubMed1979

Avian oncovirus Mill Hill No. 2: pathogenicity in chickens.

Mill Hill No. 2 (MH2), an avian tumor virus, was studied for its transforming and oncogenic effects. In tissue culture it induced transformation of chicken fibroblasts and yolk sac macrophages. When injected into the chicken, the main feature of this virus was its ability to cause liver and kidney carcinoma, in addition to sarcoma. MH2-associated viruses did not transform cell cultures but were able to cause only lymphoma in the birds. Light and electron microscopy were used in a detailed histologic study of the tumors induced by MH2 virus. An unclassified round cell sarcoma was produced in soft tissues at sites of injection; there was no evidence of origin from endothelium. In the kidney, carcinomas mixed with a malignant stroma were found. Hepatocarcinomas were the dominant tumors found in the liver. The lymphomas produced by the associated virus were poorly differentiated and highly malignant. The study illustrated the highly oncogenic potential of this virus and offered a model for the analysis of the carcinogenic events in a more specific way.

Alpharetrovirus↗
PubMed1979

The effects of noise on telephone operators.

1. One hundred twenty-nine telephone operators were given audiograms before work and again after four hours of work exposure. Since these operators habitually use the same ear for their monaural headset, the non-listening ear served as a yoked control in examining work related effects on hearing. The hearing threshold measurements conducted on the operators in this study disclosed no statistically significant shifts in mean threshold indicating no population effect for either short-term or long-term work exposure. 2. Two thousand random hours of magnetic tape recordings of operator positions disclosed the occurrence of 36 spurious signals of 94 dB SPL or above lasting from 0.4 to 145 seconds. The maximum amplitude recorded was 109 dB SPL. These tones occurred at a rate of about one per week per operator position. 3. On 36 operators reporting 51 incidents of acoustic disturbance, audiograms were obtained about 15 minutes and again at least 16 hours following the acoustic disturbance. No significant objective effects on hearing thresholds were identified.

Auditory Threshold↗
PubMed1978

Dermatofibrosarcoma protuberans with lymph node involvement. A case report of simultaneous occurrence with an atypical fibroxanthoma of the skin.

A 40-year-old man had dermatofibrosarcoma protuberans of the neck with rapid local recurrence, satellite nodules, and a cervical lymph node metastasis, occurring simultaneously with an atypical fibroxanthoma of the scrotum. These two tumors, with distinct clinical and pathologic features, are classified as histogenetically related lesions within the spectrum of the fibrous histiocytomas. The place for the dermatofibrosarcoma protuberans at the malignant end of this spectrum is clinically and ultrastructurally documented further in our patient.

Adult↗
PubMed1978

Localized congenital hepatic fibrosis presenting as an abdominal mass.

A six month old male with a liver mass localized to the right lobe that had the histological features of congenital hepatic fibrosis is presented. The mass was resected and the patient was asymptomatic 10 months after surgery. This case serves to further broaden the range of lesions with the histological features of congenital hepatic fibrosis; only one other example of localized congenital hepatic fibrosis has been previously reported.

Humans↗
PubMed1978

So-called extraskeletal Ewing's sarcoma. Report of a case with ultrastructural analysis.

The light and the electron microscopic features of an extraskeletal round-cell tumor resembling Ewing's sarcoma are described. Ultrastructural observation revealed features similar to Ewing's sarcoma of bone. Variable agrees of nuclear complexity are described. These soft tissue tumors are probably composed of undifferentiated mesenchymal cells; there is no ultrastructural evidence to indicate the cell of origin.

Adult↗
PubMed1978

Ewing's sarcoma. A light- and electron-microscopic study of 21 cases.

Twenty-one cases of Ewing's sarcoma were analyzed by light- and electron-microscopy and the fine structure compared to that described in previous publications. In the predominant "primary" tumor cells, glycogen was abundant in 53% of cases, infrequent in 33%, and rare in 14%. In three cases, microtubules, in association with glycogen, were demonstrated. The so-called differentiated "secondary" reticular tumor cells were sparsely populated in eight cases. Evidence is presented to suggest that these so-called "secondary" reticular cells are merely "primary" tumor cells in a state of regression. Secondary cells and cells with nuclear identations or convolutions were of no discernible prognostic significance. The histogenesis of Ewing's sarcoma remains an enigma but present findings support a primitive mesenchymal origin.

Adolescent↗
PubMed1978

Characterization of the human platelet alpha-adrenergic receptor. Correlation of [3H]dihydroergocryptine binding with aggregation and adenylate cyclase inhibition.

Human platelets aggregate and undergo a release reaction when incubated with catecholamines. Indirect evidence indicates that these events are mediated through alpha-adrenergic receptors. We used [(3)H]dihydroergocryptine, an alpha-adrenergic antagonist, to identify binding sites on platelets that have the characteristics of alpha-adrenergic receptors. Catecholamines compete for the binding sites in a stereo-specific manner with the potency series of (-) epinephrine > (-) norepinephrine > (+/-) phenylephrine > (-) isoproterenol. The dissociation constant (K(d)) of (-) epinephrine is 0.34 muM. Binding is saturable using a platelet particulate fraction but not with intact platelets. There are 0.130 pmol binding sites per milligram protein in fresh platelet membranes. This number represents approximately 100 binding sites per platelet. The K(d) for [(3)H]-dihydroergocryptine was 0.003-0.01 muM. The alpha-adrenergic antagonist phentolamine (K(d) = 0.0069 muM) was much more potent than the beta-adrenergic antagonist (+/-) propranolol (K(d) = 27 muM) in competing for the binding sites. The binding data were correlated with catecholamine-induced platelet aggregation and inhibition of basal and prostaglandin E(1)-stimulated adenylate cyclase. (-) Epinephrine was more potent than (-) norepinephrine in producing aggregation whereas (-) isoproterenol was ineffective. The threshold dose for inducing aggregation by (-) epinephrine was 0.46 muM. Phentolamine and dihydroergocyrptine blocked this response, whereas (+/-) propranolol had no effect. (-) Epinephrine and (-) norepinephrine inhibited basal and prostaglandin E(1)-stimulated adenylate cyclase in a dose-related manner. The concentration of (-) epinephrine inhibiting adenylate cyclase 50% was 0.7 muM. This inhibition was also blocked by phentolamine and dihydroergocryptine but not by (+/-) propranolol. The specificity of binding and the close correlation with alpha-adrenergic receptor-mediated biochemical and physiological responses suggest that the [(3)H]dihydroergocryptine binding site represents, or is closely related to, the human platelet alpha-adrenergic receptor. The ability to assay this receptor directly and to correlate these data with independently measured sequelae of receptor activation should facilitate increased understanding of the physiology and pathophysiology of the human platelet alpha-adrenergic receptor.

Adenylyl Cyclase Inhibitors↗
PubMed1977

Immune-complex glomerulonephritis in a patient with mixed connective tissue disease.

Renal involvement and hypocomplementemia in mixed connective tissue disease are reported to be rare. A patient is described here with mixed connective tissue disease and persistently low serum C'3 levels in whom renal insufficiency and nephrotic syndrome developed secondary to immune-complex glomerulonephritis. Light microscopy of the renal biopsy specimen showed predominantly a membranous lesion. Immunofluorescent staining showed granular deposition along the basement membrane of immunoglobulin G, immunoglobulin M, fibrinogen and C3. Electron microscopy showed numerous electron-dense deposits along the glomerular capillary membrane and in the mesangium.

Adult↗
PubMed1977

Renins and prostaglandins in segmental renal artery aneurysm associated with accelerated hypertension.

A patient with hypertension of sudden onset and with segmental renal ischemia due to an aneurysm in a renal artery branch underwent a nephrectomy which apparently cured his arterial hypertension. The nephrectomy specimen was studied to determine the activity of the juxtaglomerular cells and the concentration of prostaglandins in both ischemic and normal renal tissue. As compared with the normal tissue, the ischemic cortex had an increased number of heavily granulated juxtaglomerular cells. Interstitial fibrosis in the ischemic segment was associated with considerably lower tissue concentration of both prostaglandins A2 and E2 when compared with surrounding normal medulla. These findings appear to correlate well with present theories that consider renal ischemia to be associated with decreased production or response of prostaglandins that normally would counteract the effects of angiotensin.

Adult↗
PubMed1977

The value of preplacement medical examinations for nonhazardous light duty work.

A prospective study on 6,125 job applicants for light duty telephone company work is presented, which indicates that a preplacement medical evaluation is not predictive of risks relating to work attendance or job performance in nonhazardous assignments. Results show that between groups of employees, who were medically classified at the time of hire into categories with or without employment risk factors, there was no significant difference relative to sickness, accident or other absence, or to work performance during the first twelve months after hire. A work force loss of 25% is seen during the first year after hire without significant difference between groups for either numbers of employees lost or reason for loss. A cost-benefit analysis based on this study is presented, which demonstrates that the preplacement medical evaluation for light duty assignments is not cost effective. In addition, further unnecessary costs are incurred when job applicants are medically evaluated but not hired, which is shown to occur here for 27.5% of healthy applicants.

Absenteeism↗
PubMed1977

Rhabdomyoma of the pharyngeal wall.

Rhabdomyoma is a rare benign tumor of skeletal muscle, and the head and neck region is the most common extracardiac area for these tumors to occur. Twenty-one cases have previously been reported, and this report, "A Rhabdomyoma of the Pharyngeal Wall," brings the total to 22. Pathologically, these tumors show abundant polygonal skeletal muscle cells with demonstrable cross striations. Differential diagnosis of these tumors has included granular cell myoblastoma and rhabdomyoscarcoma. Treatment is usually complete excision.

Adolescent↗
PubMed1976

Hierarchical grouping analysis and skeletal materials.

The technique of hierarchical grouping analysis is examined with respect to its use as a tool in grouping skeletal remains, utilizing both continuous and certain types of discontinuous anthropometric variables. The method is found to be useful when tested with Amerind skeletal materials at the microevolutionary level, and as a technique for sexual differentiation within human and non-human primate populations. The application of this form of cluster analysis to dental data is examined.

Animals↗
PubMed1976

Postpartum hemolytic uremic syndrome.

Postpartum hemolytic uremic syndrome is characterized by the findings of renal failure and microangiopathic hemolytic anemia in the puerperium. The case reported and literature reviewed demonstrate the need for early recognition and aggressive therapy in this rare and generally fatal condition.

Acute Kidney Injury↗