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Biomedical subjects

R David

Publications and source records attributed to R David.

At least 199 records · Page 11Linked to original sources
PubMed1981

Factors affecting sperm motility. VII. Sperm viability as affected by change of pH and osmolarity of semen and urine specimens.

The effects of pH and osmolarity of semen and urine specimens on motility and velocity of human spermatozoa were studied objectively with the aid of the multiple exposure photography (MEP) method. The pH of fresh ejaculates ranged from 7.2 to 8.2 and specimens were slightly hyperosmotic ranging between 300 to 380 mOsm/kg. Gradually changing the pH and osmolarity to either side of normal values led to progressive loss of sperm motility. However, sperm velocity was slightly increased by mild alkalinization and hyperosmolarity. Spermatozoa that became immobilized by acidification regained their motility shortly after pH was restored to normal values. In the majority of instances spermatozoa lost their motility when mixed with fresh urine specimens. Neutralization of urinary pH could not protect them from this effect unless urine osmolarity was also isotonically adjusted. It is suggested that patients with retrograde ejaculation should adequately increase their fluid intake before recovery of sperm from their bladder for artificial insemination.

Humans↗
PubMed1981

Quantitative trabeculectomy.

The technique and results of a trabeculectomy are presented where the desired final intraocular pressure (IOP) is obtained by means of adjusting the thickness of sclerocorneal tissue removed to the initial pressure. The procedure was used in 35 eyes with all types of glaucoma and pre-operative pressures of up to 50 mmHg. In 78.3% of cases one operation was sufficient to control the IOP without additional medication. Two eyes had to be reoperated on, and 7 more needed additional pressure-lowering medication. The overall success rate, therefore, rose to 97.3%. The only failure occurred in an eye with irreducible acute angle-closure glaucoma where malignant glaucoma complicated the trabeculectomy. Complications included hyphaema (3), shallow anterior chamber (7)--with or without choroidal detachment--and transient rise in the IOP. All complications subsided with conservative therapy.

Glaucoma↗
PubMed1981

Racism, society, and disease: an exploration of the social and biological mechanisms of differential mortality.

Racial differentials in mortality provide important insight into the nature of mass disease in capitalist society. Not only are the differentials sizable in magnitude, they are consistent for multiple causes of death and appear to evolve in response to social development. The relationships among social factors and the biological and physical agents of disease can be identified through racial contrasts and a pattern of causation which applies to both the minority and majority populations described. Furthermore, the impact of exploitation as the primary disease-mediating factor under capitalist social relations can be estimated. This paper attempts to combine an analysis of bio-medical mechanisms with Marxist social theory in a comprehensive framework for the study of the social origins of racial differentials.

Black or African American↗
PubMed1981

Water intoxication in normal infants: role of antidiuretic hormone in pathogenesis.

Eight infants, 2 to 5 months of age, who were seen somnolence or irritability, seizures, and hypothermia are described. The symptoms developed following the ingestion of dilute formula. All infants were hyponatremic. Three patients were identified by the symptom complex and were evaluated prior to any therapeutic intervention. Plasma arginine vasopressin concentration and urinary osmolality were either normal or increased despite hyponatremia and decreased serum osmolality. These data, coupled with rapid biochemical and clinical improvement following fluid restriction and/or administration of 3% NaCl, strongly implicate the excessive release of arginine vasopressin in the pathogenesis of this syndrome of water intoxication.

Arginine Vasopressin↗
PubMed1981

Effect of ethanol upon placental uptake of amino acids.

The effect of ethanol infusion upon placental uptake of amino acids was studied in pregnant sheep. Blood ethanol levels of 150-260 mg/dl obliterated the normal uptake of amino acids by the in vivo placenta. However, when human placental villi were incubated in vitro with ethanol at 300 mg/dl, there was no inhibition of uptake of 14C alpha-amino isobutyric acid (AIB). In contrast, 2-20 mM, but not 50 or 200 micro M, acetaldehyde significantly inhibited AIB uptake (% inhibition at 90 min: 2 mM, 23.5 +/- 9.6%; 5 mM, 33.8 +/- 4.7%; 10 mM, 54.6 +/- 2.9%; 20 mM, 61.5 +/- 7.5%; p less than 0.01 for all 4 concentrations). When human placental villi were preincubated with 10 micro M acetaldehyde, washed, and incubated with 14C-AIB in the absence of acetaldehyde, there was significant residual inhibition of AIB uptake. The data suggest that ethanol-associated placental injury may contribute to the pathophysiology of the fetal alcohol syndrome.

Acetaldehyde↗
PubMed1980

[Studies of immunological status, following autologous bone marrow transplantation in man (author's transl)].

Following transplant, circulating immunoglobulin levels fell moderately and remained depressed less than 2 months for IgG, and for variable and longer periods of time for IgM and IgA. Repeated quantitative determinations of antibodies against multiple antigens did not show any decrease in the pretransplant levels. Indeed some patients developed herpes and cytomegalovirus infections to which they responded by a sharp increase in antibody titers. In 2 cases, a primary immunization was demonstrated (against CMV and BK virus) with increasing levels of IgM and IgG antibodies. Lymphocyte counts in peripheral blood returned to 500 mm# between day 10 and 29 (median day 18) and to pretransplant values within 6 weeks. Non specific stimulation of lymphocytes by mitogens in the immediate post-transplant period showed a decreased response to PHA and Con A, whereas the responses to pokeweek mitogens and alloantigens were only slightly diminished. The degree of the responses was related to the dose of cryopreserved marrow infused. We conclude that:--although the minimum dose for autologous bone marrow transplantation in man is around 0,5 10(8) nucleated bone marrow cells/Kg, much higher doses should be used to ensure faster and better restoration of immune reactivity.--The similarity of the immunological dysfunction following autologous and allogeneous bone marrow transplantation suggest that, in the immediate post-transplant period, the role of GVHD in cellular immunity depression may be minimal.

Bone Marrow Transplantation↗
PubMed1980

Elastosis in benign and malignant salivary gland tumors. A histochemical and ultrastructural study.

One hundred sixteen cases of various types of salivary gland tumors were examined for the presence of elastic tissue. Almost all the pleomorphic adenomas (97%) and all the malignant pleomorphic adenomas contained elastic tissue in varying amounts. A high percentage (82%) of adenoid cystic carcinomas also contained elastic tissue but the overall quantity was significantly less than in pleomorphic adenomas. All other salivary gland tumors studied, i.e. adenolymphomas, oxyphilic adenomas, mucoepidermoid tumor, and various variants of monomorphic adenomas, were devoid of significant elastic tissue. At the ultrastructural level, the elastic fibers were mainly seen close to neoplastic myoepithelial-like cells, and all stages of elastogenesis were present, ranging from young elastic fibers with a high microfibrilelastin ratio, usually associated with basal-membrane-like material, to mature fibers consisting mainly of an amorphous electron lucent central elastin component. It is postulated that elastic tissue in the salivary gland tumors is produced by the myoepithelial-like tumor cells rather than by tumor stromal induction as has been described in some types of breast carcinomas.

Adenolymphoma↗
PubMed1980

Langerhans' cells in a pleomorphic adenoma of submandibular salivary gland.

Large numbers of round and dendritic cells similar to Langerhans' cells of normal epidermis and other epithelia were seen within a pleomorphic adenoma of the submandibular salivary gland. These cells, which were present only in areas of non-cornifying epidermoid metaplasia, exhibited Birbeck granules with isolated terminal vesicles, cytoplasmic microfilaments, microtubules, and a few poorly developed intercellular junctions.

Adenoma, Pleomorphic↗
PubMed1980

Aberrant testicular differentiation in 46,XY gonadal dysgenesis: morphology, endocrinology, serology.

In an infant with gonadal dysgenesis and somatic anomalies, the internal and external genitalia were female but the gonads contained tubular structures suggesting male differentiation. The karyotype was 46,XY with no evidence of structural aberration or mosaicism. Hormonal metabolism and H-Y antigen expression were assayed in cultured gonadal cells. Although unable to synthesize testosterone, the cultured cells were able to convert it to dihydrotestosterone. H-Y antigen was present, perhaps at a level lower than that in cells from normal XY males. Our observations indicate that a modicum of testicular organogenesis may precede the involution that results in a streak gonad in some cases of gonadal dysgenesis.

Cells, Cultured↗
PubMed1980

Cardiac myxoma.

Ten patients with cardiac myxoma were reviewed. The ranged from 23 months to 60 years old. Echocardiography was the most helpful noninvasive diagnostic technique. The tumor was demonstrated by angiocardiography, left atrial myxomas frequently migrating to the left ventricle in diastole. Hemodynamically, left atrial myxomas were associated with moderately severe pulmonary hypertension and simulated mitral stenosis or insufficiency and right atrial myxomas, with right atrial hypertension. There were 7 myxomas in the left atrium, 2 in the right atrium, and 1 in the right ventricle. Eight patients underwent open-heart operation with removal of the myxoma, 1 had concomitant tricuspid valve replacement, and 1 had biopsy of the right ventricle only. The other patient was a Jehovah's Witness and refused operation. One patient died of cardiac arrest intraoperatively, and another died of a bilateral cerebral infarct. One patient had recurrence requiring reoperation. Postoperative hemodynamic and clinical improvement was more striking in patients with a left atrial myxoma presumably due to a normal mitral valve in contradistinction to the tricuspid valve.

Adult↗
PubMed1980

Genetic markers in glaucoma.

A number of genetic polymorphisms have been investigated in Negro and Caucasoid patients with glaucoma and the results compared with data obtained on healthy controls. A sample of 61 Negro patients was not significantly different from a sample of 238 controls with respect to 18 red cell and serum protein systems; no association between glaucoma and any of these systems could be demonstrated. The comparison among Caucasoids, using 14 systems, was made between 31 patients and 70 controls. The populations differed from each other in the rhesus and Duffy blood group systems, and a significant association between open-angle glaucoma and rhesus D (+) was found.

Blood Group Antigens↗
PubMed1980

Intraocular pressure response to corticosteroids in children.

A total of 44 children who suffered from vernal conjunctivitis were treated with topical dexamethasone 0.1% 4 times daily for 6 weeks and tested for their intraocular pressure. There was a statistically significant difference (P less than 0.01) between the responders in our group of children and a group of normal adults reported on by Armaly in 1965.

Administration, Topical↗
PubMed1980

Age-, sex-, and race-related differences in myoglobin concentrations in the serum of healthy persons.

A radioimmunoassay was used to study the relation of race, sex, and age to serum myoglobin concentrations in ostensibly healthy individuals: 75 white men, 76 white women, 75 black men, and 66 black women, ranging in age from 20 to 85 years. Mean serum myoglobin values were significantly higher in men than in women in both races (35 vs 31 microgram/L for whites and 44 vs 29 microgram/L for blacks). Black men had higher values than white men, but no corresponding difference was observed in the female population. Except for the group of black men, which consistently had the highest values for serum myoglobin, values were always higher for the older groups (greater than or equal to 50 years) than the younger, irrespective of race or sex. Serum myoglobin and age were significantly and directly correlated only among white men (r = 0.3408 p < 0.01, n = 75). If results were expressed as a myoglobin/creatinine ratio, the distinctions by race, sex, and age were partly eliminated. Reference intervals for serum myoglobin, expressed both ways, are given for different race, sex, and age groups.

Adult↗