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Biomedical subjects

R Adams

Publications and source records attributed to R Adams.

At least 163 records · Page 9Linked to original sources
PubMed1979

Hypertension screening in schools: results of the Dallas study.

The purpose of this study was to determine the prevalence of persistent blood pressure elevations in an eighth-grade population composed of three ethnic groups, and to determine the feasibility of using school health facilities for hypertension screening. Blood pressure was recorded in 10,641 subjects (90% of the total eighth-grade population) in the Dallas Independent School District. Blacks made up 46% of the population; non-Latin whites, 40.1%; and Latin-Americans, 13.9%. On the first blood pressure screening, 8.9% had systolic or diastolic pressures or both at or above the 95th percentile. Of those whose blood pressures were elevated on the first examination, 98.3% were reexamined. After the third examination, 1.2% continued to have systolic hypertension, and 0.37% diastolic hypertension. No student had diastolic pressure above 90 mm Hg on all three examinations. The prevalence of persistent hypertension was similar for the three ethnic groups. Analysis of variation in blood pressure measurements revealed that the school nurses introduced a relatively small increase in variability. These data indicate that although school screening initially identifies large numbers of students as having inconstant pressure elevations, subsequent follow-up examinations show that less than 2% have persistent hypertension.

Adolescent↗
PubMed1978

Deadtime measurements in scintillation cameras under scatter conditions simulating quantitative nuclear cardiography.

Deadtime performance of scintillation cameras is sensitive to such factors as scatter fraction and analyzer window width. Data from manufacturers and previous investigators do not predict counting-rate losses under clinical conditions. Scintillation cameras used with Tc-99m for quantitative nuclear cardiology should be evaluated for deadtime performance by the two-source method using a scatter phantom designed to simulate the spectrum from Tc-99m in the heart. Under these conditions, scintillation cameras were found to follow the paralyzable model; accurate estimates could be obtained for data losses and maximum useful counting rates in a clinical setting. A survey of 39 contemporary scintillation cameras yielded a range of paralyzing deadtime values of 4.3 to 10 musec, with a 20% window centered on the Tc-99m photopeak. For an average deadtime of 6 musec, counting rates should be maintained below 36,000 cps to avoid undue data losses in excess of 25%.

Heart Diseases↗
PubMed1977

Intracellular compartmentation of Na+, K+ and Cl- in the Ehrlich ascites tumor cell: correlation with the membrane potential.

The intracellular distribution of Na+, K+, Cl- and water has been studied in the Ehrlich ascites tumor cell. Comparison of the ion and water contents of whole cells with those of cells exposed to La3+ and mechanical stress indicated that La3+ treatment results in selective damage to the cell membrane and permits evaluation of cytoplasmic and nuclear ion concentrations. The results show that Na+ is sequestered within the nucleus, while K+ and Cl- are more highly concentrated in the cell cytoplasm. Reduction of the [Na+] of the incubation medium by replacement with K+ results in reduced cytoplasmic [Na+], increased [Cl-] and no change in [K+]. Nuclear concentrations of these ions are virtually insensitive to the cation composition of the medium. Concomitant measurements of the membrane potential were made. The potential in control cells was -13.7 mV. Reduction of [Na+] in the medium caused significant depolarization. The measured potential is describable by the Cl- equilibrium potential and can be accounted for in terms of cation distributions and permeabilities. The energetic implications of the intracellular compartmentation of ions are discussed.

Animals↗
PubMed1977

Particulate myocardial perfusion scintigraphy: its clinical usefulness in evaluation of coronary artery disease.

The determination of myocardial viability is a crucial parameter in the evaluation of a patient with coronary artery disease. Particulate myocardial perfusion scintigraphy (PMPS) is one of several methods available for this determination. A brief comparison between PMPS and two other commonly used methods is described in this review. The technique and analysis are described and applied to 194 patients with 366 surgically bypassed regions. The patients are analyzed for postoperative regional wall function and for total ventricular function as expressed by ejection fraction. PMPS is a highly accurate and unique study for clinically predicting myocardial viability.

Aged↗
PubMed1977

Changes in canine bladder perfusion with distension.

Using a radioisotope-labeled microsphere technique, canine bladder perfusion was investigated. Blood flow was measured in in flaccid and distended conditions. A slight decrease in total bladder blood flow was recorded. There was a relative decrease in bladder mucosal flow with distension. There was no difference in perfusion of dome versus trigone.

Animals↗
PubMed1976

Residual effects of hypnotic drugs: evidence for individual differences on vigilance.

Twelve healthy volunteers were given butobarbitone 100 and 200 mg, nitrazepam 5 and 10 mg and 2 lactose dummy treatments, at 23.00 hours at weekly intervals over 6 weeks according to a balanced design and using double blind conditions. Performance was studied between 09.00 hours and 17.00 hours the following day. Significant (P is less than 0.05) impairment of tapping rate and digit symbol substitution occurred. No significant differences occurred between performance after active drug and dummy in auditory vigilance, and subjective effects. Examination of individual differences in the response of subjects to the 4 hypnotic drug treatments, compared with their responses after dummy, indicated that subjects could be divided into two groups. One group consistently rated themselved as more alert after hypnotics and their vigilance performance improved. The other group consistently were more drowsy after hypnotics and their performance was impaired. It is suggested that the improvement in the first group resulted from improved sleep quality sufficient to counteract the residual effect of the hypnotic, whereas the second group merely showed the residual effects of the drugs.

Adult↗
PubMed1976

Passive cation movements in the Ehrlich ascites tumor cell: the effects of 2,4,6-trinitrobenzene sulfonic acid.

We have investigated the effects of 2,4,6-trinitrobenzene sulfonic acid (TNBS), an amino reactive reagent, on passive cation movements in Ehrlich ascites tumor cells. Incubation of tumor cells with TNBS (3 mM) results in a two phase association of TNBS with the cells. An initial, rapid phase, presumably at the level of the membrane, is independent of temperature, while the second phase increases linearly in time and is temperature dependent. Kinetic analyses of Na+ movements indicate that TNBS: (1) inhibits Na+ movement from a slowly exchanging cellular compartment, but is without effect on a more rapidly exchanging compartment; (2) does not alter net Na+ accumulation in transport-inhibited cells; and (3) is without effect on non-exchange Na+ efflux at 0 degrees C. The actions of TNBS on K+ movements depend upon temperature and the continued presence of TNBS in the environment. At 22 degrees C two minute exposure of the cells to TNBS leads to 77% inhibition of K+ efflux. With continued exposure to TNBS, the inhibition is only 42%. Reduction of the temperature to 0 degrees C decreases K+ efflux in control cells by 82%. Two minute exposure to TNBS enhances K+ efflux by 50%, while continuous exposure increases it by 144%. These results suggest: (1) TNBS interacts with several classes of membrane sites which are involved with the regulation of passive cation movements; and (2) passive Na+ and K+ movements across the cell membrane proceed by different pathways.

Biological Transport↗