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Biomedical subjects

M J Siebers

Publications and source records attributed to M J Siebers.

7 recordsLinked to original sources
PubMed1992

Hyperthyroidism as a cause of atrial fibrillation in long-term care.

BACKGROUND: We measured sensitive thyrotropin-stimulating hormone (sTSH) in 50 consecutive nursing home patients (39 men) with atrial fibrillation to determine the frequency of hyperthyroidism. METHODS: Patients were identified in a long-term care facility by an electrocardiogram demonstrating atrial fibrillation. The sensitive thyrotropin-stimulating hormone assay had a detection limit of less than or equal to 0.02 mU/L (normal range, 0.46 to 3.60 mU/L). RESULTS: No subject had a suppressed sensitive thyrotropin-stimulating hormone. CONCLUSIONS: Hyperthyroidism is not a common cause of atrial fibrillation in male nursing home residents.

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PubMed1990

Analysis of angiotensin II binding to human platelets: differences in young and old subjects.

We examined the binding of radiolabeled angiotensin II (AII) to human platelets to characterize the apparent increase in AII receptors observed in older subjects. At 22 degrees C, the amount of radioactivity associated with platelets from older subjects increased continuously for more than 2 hours. The same amount of radioactivity was displaced by addition of unlabeled AII at 30 min and 60 min. In the presence of phenylarsine oxide, in the cold, or when labeled antagonist was the ligand, binding came to equilibrium by 30 min. High pressure liquid chromatography demonstrated that 125I-AII was the major radioactive compound in the supernatant and platelets after incubation, but the platelets also contained radiolabeled AII fragments. Thus, some degradation accompanied interaction of AII and platelets. Phenylarsine oxide did not prevent degradation of bound AII, suggesting that degradation precedes internalization. On average, maximum binding was greater in older subjects whether platelets were incubated with 125I-AII alone, with 125I-AII and phenylarsine oxide to prevent internalization, or when the competitive inhibitor 125I-sar1,ile8-AII was the radioligand. Variability of binding among subjects also increased with age. Thus, platelets bind, degrade, and internalize AII, and the three processes occur to a greater extent in platelets from some, but not all older subjects.

Adult↗
PubMed1986

Platelet angiotensin receptors in young and old humans.

Platelets from healthy human volunteers were studied for angiotensin II (AII) binding sites. Platelets were isolated from whole blood by differential centrifugation, and binding sites were analyzed by Scatchard plots of radioactive ligand binding data. The number of platelet AII receptor sites was significantly higher in human beings of advanced age compared with younger persons. The affinity of receptor sites was not different in young and old participants. The increased number of binding sites bore no relationship to salt intake as documented by history, plasma renin activity, or blood pressure. A significant portion of the increase in platelet AII receptor sites in older adults in this study is related directly to the age of the individuals.

Adult↗
PubMed1985

Increasing the pneumococcal vaccination rate of elderly patients in a general internal medicine clinic.

To improve the pneumococcal vaccination status of an elderly patients group, those older than 64 years of age were identified from a computer file of all continuing care patients in a general internal medicine clinic. In a randomly chosen study group (N = 163), 91 elderly patients (56 per cent) had received the pneumococcal vaccine. Factors associated with a higher rate of pneumococcal vaccination included receiving the previous year's influenza vaccine, a medical problem list attached to the patient's chart, active clinic status (i.e., seen in the year before the study began), and more than two problems listed in the computer record. Letters encouraging pneumococcal vaccination were then sent to patients who had not been vaccinated. Twenty of 72 patients (28 per cent) who received the letter were vaccinated during the next year; 8 per cent of control patients (three of 39) who did not receive the letter were vaccinated. The 95 per cent confidence limit for the relative difference between the study and control group is 6 to 53 per cent. The relative difference was also significant for influenza vaccination between the intervention group and the portion of the control group that had not been vaccinated at the first chart review. Factors associated with pneumococcal vaccination rate following the mailing of the reminder letter were active clinic status and being up to date for either influenza or tetanus vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)

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