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Biomedical subjects

R David

Publications and source records attributed to R David.

At least 145 records · Page 8Linked to original sources
PubMed1987

Adrenal function in thalassemia major following long-term treatment with multiple transfusions and chelation therapy. Evidence for dissociation of cortisol and adrenal androgen secretion.

Eight patients with beta-thalassemia who were given long-term treatment with combined multiple transfusions and chelation therapy underwent adrenal testing. The six male and two female patients ranged in age from 7 to 19 years. Six of eight patients had delayed bone ages and height greater than 2.5 SDs below the mean. Of the six patients more than 13 years of age, two had clinical evidence of isolated adrenarche and only one had evidence of true puberty. Cortisol levels were similar in patients and controls at zero time (10.6 +/- 1.8 micrograms/dL [292 +/- 50 nmol/L] vs 10.8 +/- 1.4 micrograms/dL [298 +/- 39 nmol/L]) and at 60 minutes (26.6 +/- 2.5 micrograms/dL [734 +/- 69 nmol/L] vs 24.9 +/- 1.9 micrograms/dL [687 +/- 52 nmol/L]) after insulin hypoglycemia (all values are the mean +/- SE). During an eight-hour infusion of ACTH, cortisol responses in the patients with thalassemia were not significantly different from those of controls. Baseline levels of the adrenal androgens dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) were significantly lower in the subjects with thalassemia compared with controls of similar bone age and pubertal status. The prolonged ACTH infusion caused a significant increase in the DHEA level (79.2 +/- 14.7 ng/dL [2.74 +/- 0.51 nmol/L] vs 538.6 +/- 38.1 ng/dL [18.67 +/- 4.79 nmol/L]) and the DHEA-S level (37.5 +/- 10.8 micrograms/dL [1.02 +/- 0.29 mumol/L] vs 70.5 +/- 18.3 micrograms/dL [1.19 +/- 0.50 mumol/L]) in the patients. The patients' peak stimulated levels of DHEA-S were significantly lower than those of the controls, whereas peak levels of DHEA were similar in the patients and the controls. These results indicate that combined multiple transfusions and chelation therapy preserve the integrity of the ACTH-cortisol axis in patients with thalassemia. The reduced levels of adrenal androgens, short stature, and delayed puberty noted in our patients suggest, however, that alternative approaches to the therapy of thalassemia are needed.

Adolescent↗
PubMed1987

Epidemiology of intraocular pressure in a population screened for glaucoma.

This study evaluated the association between intraocular pressure and various sociodemographic characteristics, ocular findings, and cardiovascular risk factors in a population screened for glaucoma. A total of 2594 subjects older than 40 years residing in three urban areas of southern Israel participated. Of those screened 6.1% had a raised intraocular pressure (IOP greater than or equal to 21). The mean IOP increased with age, was higher among persons born in Africa or Asia than those born in Europe or America, higher among myopes than hypermetropes and among those with an enlarged cup-disc ratio (CDR). Analysis of variance tests indicated that refractive status, CDR, age, country of birth, and diabetes were each independently associated with IOP. In addition, associations between raised intraocular pressure and age, country of birth, myopia, CDR, diabetes, and glaucoma in the family were found.

Adult↗
PubMed1987

Immunocytochemical localization of hFSH as an index of Sertoli cell function in the human testis.

The FSH receptor in the human testis has not been well characterized in vivo. Using an immunoperoxidase technique we have attempted the immunocytochemical localization of FSH in testicular tissue from patients with a variety of disorders including oligo- or azoospermia (N = 6), cryptorchidism (N = 3), and prostatic carcinoma (N = 3). Specific staining for hFSH was observed inside the seminiferous tubule, generally near the basal membrane in all except the cryptorchid patients. Specific staining was also localized in the luminal area of the seminiferous tubule. In most cases, FSH-positive cells were also found in the interstitium, with a minority of the cells being macrophages. The latter were more prevalent in the undescended testes and in orchiectomy specimens from patients with prostatic cancer. The pattern of FSH localization observed in this study probably represents receptorbound hormone, and may reflect damage to the Sertoli cell and its tight junctions. Further study of the changes in receptor distribution as an indication of Sertoli cell malfunction, may be helpful in our understanding of human testicular disorders.

Adult↗
PubMed1987

Treatment of elevated intraocular pressure with concurrent levobunolol and pilocarpine.

Between July 1983 and January 1986, 54 patients with open-angle glaucoma or ocular hypertension were treated for 3 months with 2% pilocarpine hydrochloride (given four times daily) and one of two beta-adrenoceptor blocking drugs, levobunolol hydrochloride (0.5% [17 patients] or 1% [19 patients]) or 0.5% timolol maleate (18 patients), given twice daily. Before entry into the study all patients had had stable intraocular pressure (IOP) with treatment with 0.5% timolol and 2% pilocarpine. Stable IOP was successfully maintained in up to 88% of the patients in the two levobunolol-pilocarpine groups and in 83% of those in the timolol-pilocarpine group. Two patients experienced adverse reactions: one, who received timolol and pilocarpine, suffered blepharoconjunctivitis, and the other, who received 1% levobunolol and pilocarpine, experienced bradycardia. The results indicate that the levobunolol-pilocarpine regimens were as safe and effective as the timolol-pilocarpine regimen in stabilizing IOP.

Adrenergic beta-Antagonists↗
PubMed1987

Osteomyelitis, acute and chronic.

In certain patient populations, osteomyelitis is a significant clinical problem. The judicious use of plain film radiographs and radionuclide bone imaging by the imaging consultant has a critical role in the early detection and diagnosis of osteomyelitis. This complementary imaging approach produces the highest and greatest accuracy in the documentation of skeletal infections. Inadvertent delay in the initiation of appropriate therapy can be obviated utilizing these imaging techniques and undue morbidity averted.

Acute Disease↗
PubMed1986

Juvenile autoimmune thyroiditis. Hormonal status at presentation and after long-term follow-up.

Thirty children and adolescents with the clinical diagnosis of juvenile autoimmune thyroiditis (JAT) were studied. Twenty-six patients were female and four were male. The median age at diagnosis was 12.9 years (range, 7.5 to 17.3 years). At the initial evaluation, endocrine studies revealed that 40% of the patients were euthyroid, while 33% had compensated hypothyroidism and 27% had overt hypothyroidism. Seventeen patients, 16 of whom received thyroid hormone replacement therapy for a median period of 26 months, were followed up on a long-term basis after discontinuation of therapy. Seven (87%) of eight patients who were initially euthyroid have remained so for a median period of 28 months after treatment and a median period of 50 months since diagnosis. Four (44%) of nine patients who initially had hypothyroidism (either compensated or overt) have reverted to a euthyroid state and have remained so for a median period of 33 months after discontinuation of therapy. Neither the size of the thyroid gland nor the pattern or absolute titer of thyroid autoantibodies correlated with functional status. These results indicate that individuals with euthyroid JAT may remain euthyroid for many years and that a substantial percentage of patients with hypothyroid JAT will experience resolution of thyroid dysfunction.

Adolescent↗
PubMed1986

Dominating redox systems in lakes and rivers; thermodynamic interpretation of in-situ measurements with a platinum electrode.

Thorough studies of 28 water bodies, predominantly lakes from the younger moraine area of Schleswig-Holstein, Northern Germany but also some peat bog waters in Niedersachsen, Northern Germany and lake Balaton in Hungary, showed the presence of at least six redox systems: NO3-/NO2-; NO3-/NH4+; NO2-/NH4+; So/HS-; So/H2S; and probably Fe(OH)3/Fe2+. Depending on the physico-chemical conditions one of these becomes the dominant system determining the electric potential measured with the platinum electrode. The platinum electrode does not respond to any oxygen dominated redox system. The corresponding theoretical redox equations seem to apply to almost all water bodies such as freshwater lakes, rivers, brackish water bodies, sea water and sometimes even humus rich water bodies from peat bogs and black water streams, hydromorphic soils, sediments and sewage sludge. The equations were found not to be valid for some heavily polluted effluents from lakes. The following points are discussed on the basis of these findings: the redox systems to which the normal platinum electrode reacts under natural conditions; equations of redox systems relevant in natural waters; methods of determination of the dominating redox system.

Electrochemistry↗
PubMed1986

Liberation of surface and internal platelet-associated IgG (PA-IgG) during platelet activation.

The relationship between platelet-associated IgG (PA-IgG) of intact platelets to that of lysed platelets has been studied using a competitive ELISA. In platelets from 20 normal individuals mean surface PA-IgG constituted 35% of mean total PA-IgG and showed a significant linear relationship with total PA-IgG. In platelets from 61 patients with various forms of thrombocytopenia including that with immune causes, 38 showed a similar proportion of PA-IgG on the surface after storage at 2 degrees C, as seen in normal platelets, while in 23, levels of surface and total PA-IgG were equal. Normal platelets activated with thrombin or calcium ionophore A23187, also had levels of surface PA-IgG close to total PA-IgG. Supernatants of platelet suspensions activated with aggregating agents contained increased amounts of IgG and when the platelets were washed, both total and surface PA-IgG were decreased. Liberation of IgG from platelets was slower than that of [14C]serotonin but was decreased by release reaction inhibitors. Platelets treated at 2 degrees C with soluble heat-aggregated IgG, which binds to the Fc gamma receptor, showed increased surface PA-IgG, but, after incubation at 37 degrees C, although [14C]serotonin was released, PA-IgG levels were no longer increased. Thus since platelet activation, including that mediated by IgG binding to the Fc gamma receptor, causes PA-IgG release, levels of both surface-located and total PA-IgG may be affected by platelet activation, either in vivo, or in vitro during sample preparation and assay.

Blood Platelets↗
PubMed1986

Different platelet specificities of heparin-dependent platelet aggregating factors in heparin-associated immune thrombocytopenia.

Delayed onset heparin-associated thrombocytopenia (HAT) is thought to be a result of formation of antiplatelet antibodies which cause platelet aggregation in the presence of heparin. Platelet aggregation in response to serum from patients with HAT has been studied in platelet-rich plasma (PRP) from a panel of normal blood donors. Heparin-dependent aggregation with any HAT serum occurred in PRP from only some donors. PRP from the non-responding donors did, however, aggregate in the presence of heparin with other HAT sera. The same patterns of aggregation or lack of response to HAT sera were seen in washed platelet suspensions. Heparin (0.06-2 U/ml) did not cause aggregation in the presence of normal serum with PRP from these donors. However, in PRP from four of the 17 individuals studied, heparin (0.25-1 U/ml) alone caused rapid platelet aggregation and some HAT sera heated at 56 degrees C caused platelet aggregation without added heparin. Sub-aggregating concentrations of adrenaline could replace heparin in promoting aggregation by heated HAT sera in PRP of the other donors. HAT IgG showed the same platelet specificities as the serum in causing either heparin- or adrenaline-dependent aggregation. Thus in HAT, antibodies are directed towards different platelet antigens which are expressed differently in different individuals. Platelet activation by heparin and adrenaline either exposes these antigens or causes aggregation of antibody-coated platelets.

Antibody Specificity↗
PubMed1986

Iridotomy with red krypton laser.

Iridotomy with red krypton laser instead of blue-green argon laser was performed on 68 eyes with various types of angle-closure glaucoma. Patent iridotomy was obtained in all the eyes, mostly in one working session. In eight eyes secondary closure by pigment needed reopening with a few applications at the iridotomy site. There were no immediate or late complications of importance, the main advantage of the technique being the avoidance of the corneal epithelial and endothelial burns which commonly occur during argon laser iridotomy, particularly when the anterior chamber is shallow.

Glaucoma↗
PubMed1986

The biological concept of race and its application to public health and epidemiology.

The category of race is widely used in public health. Although its significance may be clear-cut in some practical situations, an adequate theoretical construct for the concept of race does not exist. Public health appears to lag far behind the other biological sciences in the effort to grapple with the idea of race and its implications for the nature-nurture question. This paper outlines the current anthropological and social perspective on race, and applies this view to problems of disease epidemiology. It is proposed that uncritical use of the traditional biological concept of race has distorted etiological thinking in public health and has proven an obstacle in the development of effective intervention strategies. The pragmatism of medicine and its isolation from social science may account for much of this backwardness.

Cultural Characteristics↗