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Biomedical subjects

R N Pierson

Publications and source records attributed to R N Pierson.

At least 181 records · Page 10Linked to original sources
PubMed1985

Body composition studies in patients with the acquired immunodeficiency syndrome.

Body composition studies were performed in 33 patients suffering from the acquired immunodeficiency syndrome (AIDS). Studies included measurements of total body potassium, fat, and total body and extracellular water volumes plus serum retinol binding protein concentration, iron binding capacity, and albumin concentration. AIDS patients were underweight (p less than 0.001) and were depleted of potassium (p less than 0.001) with the lowest values occurring in patients close to death at the time of study. Body fat contents also were reduced. Intracellular water volumes were decreased in the AIDS patients (p less than 0.001) with a relative increase in extracellular water volume (p less than 0.001). Serum protein concentrations were decreased in the AIDS patients. Longitudinal studies did not demonstrate tissue repletion in patients with AIDS, despite apparent clinical stability. These studies demonstrate that severe, progressive malnutrition occurs in patients with AIDS. If malnutrition can be shown to have a deleterious effect upon the disease course, therapy of malnutrition may play an important role in the treatment of this disorder.

Acquired Immunodeficiency Syndrome↗
PubMed1985

First-third ejection fraction: is the first-pass radionuclide method accurate?

Previous reports have suggested that left ventricular first-third ejection fraction (EF) can be obtained from the left ventricular time-activity curve derived from first-pass radionuclide angiography based on Anger camera data. The validity of this technique was assessed by: a study of beat-to-beat variations in data from 15 patients in which electrocardiographic data were simultaneously recorded, and a computer simulation incorporating the application of Poisson statistics to appropriate count rate data. The results of patients studies showed no consistent trend in any first-third parameter obtained from consecutive beats in individual subjects, and unacceptably high statistical uncertainty in the calculation of the first-third ejection fraction. The weighted standard deviation of the first-third ejection fraction in each of 15 patients studied averaged 7.5 EF units, while first-third ejection fraction averaged 22.9 EF units. The relative error averaged 32%. The computer simulation indicated a high relative error of 47% associated with the first-third ejection fraction at typical end-diastolic count rates of 200 per frame from 1,000 computer Poisson randomizations of an appropriate analog volume curve. The results render the first-pass radiocardiographic method invalid for determining first-third ejection fraction.

Adult↗
PubMed1984

Body potassium by four-pi 40K counting: an anthropometric correction.

Four-pi whole body counting for the 1.46 meV photon of 40K has apparent advantages over single-crystal or two-pi counters in efficiency and in subject geometry independence. However, our studies of obese populations have disclosed a systematic undermeasurement of 40K, suggesting that nonhomogeneous K distribution results in systematic undercounting of 40K. In the current study 42K, emitting a 1.52 meV photon, was used in 109 volunteers ranging from 50 to 181 kg, and multiregression covariance analysis was applied to develop correction formulas based on anthropometrics. These corrections quantitatively account for the unappreciated loss of 40K and 42K photons in annular adipose tissue that surrounds the lean body, in which most K+ is concentrated. The correction ranges from 1 to 28% and is a linear (although different) function of weight in both sexes. Thus corrected, body potassium measurements, taken in conjunction with exchangeable sodium and water measurements, provide estimates for whole body osmolality that match measured serum values. Such a quantitative accounting for previously "lost" cation in 58 subjects provides independent evidence for the appropriateness and accuracy of the correction. With this correction, body potassium was recalculated in the 1,492 adult members of a previously reported group of 3,083 subjects.

Absorption↗
PubMed1983

Prediction of the resting metabolic rate in obese patients.

Resting metabolic rate (RMR) was measured in 154 women and 48 men before the beginning of a weight reduction program. In both sexes there were significant univariate correlations between RMR and fat-free mass, body fat, weight, fat cell weight, and fat cell number (from total body water). Women also showed significant correlations between RMR and fat cell number (from total body potassium), free triiodothyronine index, and fasting and postglucose insulin levels. Multiple regression analysis showed that both fat-free mass and fat cell weight and number were significant predictors of RMR. The contribution of fat-free mass was three to five times greater per kg than that of body fat. There was no significant contribution of thyroid hormones or insulin to the prediction of RMR. Fat cell number and fat cell weight were significant predictors of RMR, whether determined from body water, body potassium, or a formula using both water and potassium. There was no significant difference in regression coefficients between men and women. Thus the difference in RMR between the sexes is probably caused by the higher proportion of fat-free mass in men. The effect of age was small and not statistically significant.

Adipose Tissue↗
PubMed1982

Body composition in affective disorder before, during, and after lithium carbonate therapy.

The body composition of three unipolar and 17 bipolar patients, studied during the depressive state, was compared with that of 48 controls. The ratio of extracellular to intracellular water content was significantly less in male patients than in male controls: the difference between female patients and female controls was not statistically significant. In patients of both sexes, residual sodium concentration was greater in patients than in controls. The intracellular content of potassium was the same in patients as in controls. In six patients, body composition was studied prior to lithium carbonate therapy, after 17 days of treatment, and 17 days after discontinuing administration of the drug. The significant changes were a decrease in body weight during therapy, and a decrease in body water content and an increase in residual sodium concentration after drug treatment was discontinued.

Adipose Tissue↗
PubMed1982

Body composition measurements in normal man: the potassium, sodium, sulfate and tritium spaces in 58 adults.

The aqueous phase of total body composition varies with sex, and changes with age, necessitating age, sex and method-specific normal values. Consensus has developed for the methods most suited to clinical studies. 3H20 for water, 35SO4 for ECW, 24Na for NAc, and 40K for body potassium were used in 58 normal volunteers aged 19-80, 30 men and 28 women. This report shows significant age regressions in both sexes for total body water and intracellular water, and for both Na and K when referenced to body water. Combination of these findings with the highly age related decrease in total body potassium confirms previous studies that body cell mass decreases with age. Intracellular K+ and Na+ at the zero age intercept are 130 and 14.5 for males, and 124 and 24mEq/1 for females respectively. Secular decrease in K+ and increase in Na+ concentrations in the average cell are suggested although not established. Values for normal body composition, in subjects healthy by all available criteria are in some instances age and sex dependent, but in all parameters except fat show wide normal range (SD = 7% of mean) which derive more from biological variation than from limitations of measurement precision. However, use of body water rather than weight succeeds in narrowing this wide range, and is a more logical denominator which is readily subject to accurate measurement. In serial studies of the same subject, significant changes can be measured which are well within the normal range.

Adult↗
PubMed1982

Continuing medical education in New York County: physician attitudes and practices.

New York County physicians were surveyed by questionnaire concerning their attitudes and practices regarding continuing medical education (CME). There were 1,558 responders, and they included those practicing in shared health facilities (SHF) and random samples of academicians on the faculties of the four medical schools and of the entire physician population of Manhattan. Reading professional books and journals was regarded as by far the most important CME activity by all three groups of physicians, and this activity consumed about four hours per week. All physicians spent several days and often as much as two weeks per year attending professional meetings and formal postgraduate courses. The former were rated as not very useful and the latter as quite useful for CME. Major impediments to CME participation for all groups were time away from home and practice, expense, loss of income, and scheduling problems. Relevance, quality, and organization of CME courses were not major impediments. SHF physicians differed little from other physicians in their attitudes, perceptions, and practices concerning CME.

Attitude of Health Personnel↗
PubMed1981

Combined effects of alcohol and lithium on body composition in the rat model.

Alcohol markedly enhances Li+ retention in blood and muscle in rats taking Li and alcohol. The marked enlargement of the exchangeable Na+ space which occurs with alcohol alone, Li+ alone, and to an even greater extent with combined therapy, results from extensive mobilization of "bound" bone sodium, which is transferred to intracellular sites, demonstrably in skeletal muscle, and presumably in other cells. This 87% increase in measured intracellular Na+, and concomitant decrease in K+, would be predicted to produce profound effects on the intracellular ionic milieu, and on membrane function. Lithium is associated with a decrease in food and fluid intake, and this effect is enhanced by alcohol. However the decrease in intake did not result in nutritionally significant deficits in either group, and therefore the observed abnormalities in body composition did not result from caloric, protein, K, Na, or Ca deficiency.

Animals↗
PubMed1981

A possible low intracellular potassium in obesity.

In comparison with lean marathon runners whose fat content was 15%, obese subjects with a fat content of 55% showed a 36% reduction in intracellular potassium. It is hypothesized that as much as 60% of this decrease may have been due to the lower proportion of muscle (which has the highest intracellular potassium of any tissue) in the fat free mass of very obese subjects. The remainder of the decrease seems to have been a measurement artefact owing to self-absorption of gamma rays by adipose tissue, most of which is distributed over potassium rich lean tissue. The low intracellular potassium values found in obesity should not be interpreted as necessarily signifying potassium deficiency.

Adipose Tissue↗
PubMed1981

Alcohol-induced lipid change in th lung.

Quantities and qualities of lipids in lung lavage and lavaged lung tissue were studied in ethanol-fed male Sprague-Dawley rats. Experimental rats received 36% of daily energy as ethanol for 7 weeks and each control rat, receiving an isocaloric amount of sucrose, was pair-fed with an experimental rat. Body weight gain and lung protein content in these two groups were similar. The mean lung dry weight of ethanol-fed rats as compared to controls was significantly elevated. The quantity of phosphatidylcholine (PC), a key surfactant lipid, recovered from lung lavage of ethanol-fed rats was double that of controls, but the proportion of palmitate in its fatty acids was reduced. The content of cholesterol and cholesteryl ester in lung lavage of ethanol-fed rats was nearly twice that of controls but the content of triglyceride was not different. The quantity and quality of PC in lung tissue were not significantly different between these two groups. Triglyceride content of lung tissue in ethanol-fed rats was nearly three times that of controls. Ethanol increased the proportion of oleic and decreased the relative amount of palmitic, palmitoleic, and linoleic acids in triglycerides of lung tissue.

Animals↗
PubMed1979

Adipose cell morphology and control of lipolysis in a patient with partial lipodystrophy.

A previously unreported patient with partial (cephalothoracic) lipodystrophy is described. Glucose tolerance and plasma lipids were normal, but plasma insulin increased to 340 muU/ml during an oral glucose tolerance test. Plasma free fatty acids were appropriately suppressed by oral glucose, insulin, and nicotinic acid, and were increased by infusion of norepinephrine. The lipolytic responses was also normal in response to two stimuli for endogenous catecholamine release: upright posture and 2-deoxyglucose infusion. There was a gradual development of postural hypotension in response to upright posture despite appropriate reflex tachycardia. Anhidrosis was present over the lower half of the body during this test, in a distribution corresponding to the area of adipose tissue hypertrophy. Anhidrosis was also seen in this region in response to warm ambient temperature. Adipose cells from the atrophic area were smaller than those from the hypertropic area, but the atrophic cells were only 65% of the volume of the hypertrophic cells by two different methods. Thus, loss of cells occurred. Glucose-1(-14)C utilization and in vitro lipolysis were similar in the two cell preparations; the difference were explicable by cell size and did not suggest a metabolic abnormality. Counts of unmyelinated nerves were similar in the two areas. These findings indicate that in this patient the lipodystrophy was associated with normal fat cells and an autonomic dysfunction. However, the findings cannot completely explain the pathogenesis of her disorder. Loss of fat cells, rather than symmetrical shrinkage, occurred in the upper half of the body.

Adipose Tissue↗
PubMed1979

Cardiovascular nuclear medicine: an overview.

Some of the available cardiovascular nuclear medicine methods are incompletely validated, and others are incompletely developed. They are, however, of very great potential in diagnostic cardiology, and in patient management. A new era of clinical research and acute care monitoring has been opened by serial, noninvasive, hemodynamic measurements of right ventricular as well as left ventricular function. Stress testing has become more specific, and should, with future developments, become more specific, and should, with future developments, become more sensitive, using radionuclide procedures. Serious quality control and validation questions concerning thallium stress testing must be addressed. Intracoronary injection of radiogases has great potential, although minimal present application. Emission computerized tomography will be an important research tool. Compartmental analysis modeling of first pass tracer injections has much to offer, but is not yet validated. Present growth rate of these procedures is very rapid. Fully developed, cardiovascular nuclear medicine may become the largest component of clinical nuclear medicine practice.

Adult↗
PubMed1978

Extracellular water measurements: organ tracer kinetics of bromide and sucrose in rats and man.

Bromide and sucrose distributions were measured as functions of time after tracer injection into 14 rat organs that accounted for 93% of body wt, with the goal of evaluating the use of bromide and sucrose as tracers for the extracellular water volume (ECW). The tracers, Na, 82Br, 125I-labeled human serum albumin, [14C]sucrose, and 3H2O, were used to calculate bromide and sucrose content in red cells, plasma, and 13 blood-free organs. Selective concentration of Br- occurs in RBC, stomach, and skin, accounting in part for the discrepancy between the Br- space and the smaller ECW volume as derived from other methods. Sucrose is rapidly metabolized in the rat and its 14C tracer cannot be used for ECW determination in this species. The kinetics of Br- distribution were estimated in rats and in 16 human subjects by measuring plasma disappearance values and specific organ uptakes. A pharmacokinetic compartmental model was derived, containing explicit parameters for blood flow, diffusion constants, and ECW spaces separately for each organ. Precise fitting of experimental bromide data was achieved for the rat; satisfactory fitting was also achieved in man from more limited plasma and biopsy data.

Animals↗
PubMed1978

Effect on body water of running 10 miles.

Despite a 2.3% weight loss in 10 men who ran 10 miles, extracellular water (ECW) increased by 3.5%. Total body water (TBW) measured as tritium space increased by 2.4%, and intracellular water (ICW), inferred as the difference between TBW and ECW, increased by 1.8%. The increase in tritium space probably represents increased nonaqueous hydrogen exchange in the postexercise period ond casts doubt on the validity of TBW and ICW when measured immediately after exercise.

Adult↗