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Biomedical subjects

R N Pierson

Publications and source records attributed to R N Pierson.

At least 163 records · Page 9Linked to original sources
PubMed1989

Chemical determination of human body density in vivo: relevance to hydrodensitometry.

A chemical approach to establishing human body density in vivo was developed by combining recently developed noninvasive methods. Four compartments were measured: protein (P; prompt-gamma neutron activation), water (A; 3H2O dilution), mineral (M; dual-photon absorptiometry and delayed-gamma neutron activation), and fat (F; dual-photon absorptiometry). By this model body weight is equal to P + A + M + F. This approach was applied to 13 healthy adults (8 females and 5 males). The four compartments accounted for greater than 97% actual body weight. Calculated density based upon composition agreed within 0.6 +/- 0.4% (mean +/- SD) with density (D) measured by hydrodensitometry [calculated D (g/cc) = 0.86 measured D +0.15; r = 0.94, p less than 0.001]. The average calculated lean (P + A + M) density of 1.096 +/- 0.007 g/cc agreed closely with three classic human cadaver studies (1.100 g/cc). This multicompartment approach provides a new opportunity to estimate human body density in vivo and to refine body composition methods based upon an assumed but inadequately validated constant lean density.

Absorptiometry, Photon↗
PubMed1989

Body fat from body density: underwater weighing vs. dual-photon absorptiometry.

We measured fat in 286 healthy volunteers by underwater weighing (FUWW) and dual-photon absorptiometry (FDPA) to develop a translation table for the differing results from these entirely different techniques and to study the sources of these differences. In 99 males and 187 females aged 19-94 yr, fatness was 7-47%. Prediction equations are presented for FUWW-FDPA (delta F), density of lean body mass (DLBM), and FDPA. FUWW and FDPA were significantly different from each other (P less than 0.01). Calculated DLBM is less than the assumed constant of 1.10 (P less than 0.01), ranging widely from 1.05 to 1.13 and being highly correlated with the ratio of total body bone mineral to lean body mass (TBBM/LBM). delta F, the differences between FUWW and FDPA measurements in individual subjects, varied widely (-7 to +11% in males and -18 to +13% in females). The difference was positively correlated with the DLBM. FUWW was no better than anthropometrics in equations for predicting FDPA. The FDPA predicted from anthropometrics showed smaller standard errors than when FUWW was used. Neither anthropometrics nor FUWW equations are clearly superior to those previously available.

Adipose Tissue↗
PubMed1989

Primate cardiac allo-and xenotransplantation: modulation of the immune response with photochemotherapy.

Survival of heterotopic allo- and xenografts was studied in a primate cardiac transplantation model. Initially, animals were presensitized to donor xenoantigens by blood transfusion and treated with strategies designed to elicit pretransplant immunosuppression. These animals underwent rapid rejection whether treated with ciclosporin and conventional immunosuppression, autologous sera, sensitized lymphocytes, or photochemotherapy. In a nonsensitized xenograft study, xenografts were maintained for prolonged periods with a combination of ciclosporin and photochemotherapy. All animals treated with photochemotherapy demonstrated periodic suppression of the mixed leukocyte culture response to their donor. Inhibition of lymphocytotoxic antibody was achieved only in animals treated with both ciclosporin and photochemotherapy. Xenosensitized animals were secondarily exposed to donor alloantigens. These animals were successfully allografted. Ciclosporin therapy was terminated and the animals maintained by photochemotherapy alone. This preliminary trial indicates that a combination of ciclosporin and photochemotherapy may be of value in maintaining concordant xenografts and preventing antibody mediated rejection.

Animals↗
PubMed1989

Body mass repletion during ganciclovir treatment of cytomegalovirus infections in patients with acquired immunodeficiency syndrome.

Disseminated cytomegalovirus (CMV) infection is a common complication of acquired immunodeficiency syndrome and contributes significantly to its morbidity and mortality. Ganciclovir, a guanosine analogue, inhibits CMV replication in vitro and in vivo, and its use can stabilize the clinical course of an affected patient. We examined the changes in body composition that occurred in four untreated patients and in eight patients who were treated with ganciclovir for serious CMV infections. Untreated patients lost weight, depleted body cell mass, as determined from total-body potassium measurements in a whole-body counter, lost body fat, as estimated from anthropometric measurements, and had a progressive fall in serum albumin concentration. In contrast, treated patients gained weight, repleted body cell mass and body fat, and increased serum albumin concentration during a three-month follow-up. In this study, it was estimated that ganciclovir therapy resulted in a net energy conservation of 2629 kJ/d. The ability to promote body cell mass repletion may be considered a demonstration of the efficacy of ganciclovir in the treatment of serious CMV infections in patients with acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Incidence of exertional right ventricular wall motion abnormalities in patients with coronary artery disease.

To evaluate the role of analysis of right ventricular function with exercise in patients with presumed coronary artery disease referred for radionuclide ventriculography, the records of 55 patients referred to our laboratory over a 19-month period were reviewed. All underwent rest and exercise first-pass radionuclide stress testing and cardiac catheterization within a period of four months. Three groups were identified: (1) patients with normal exercise right ventricular function (n = 24); (2) patients with exercise-induced right ventricular regional wall motion abnormalities (n = 15); and, (3) patients with abnormal resting right ventricular function without new exercise abnormalities (n = 16). Patients in each group were similar in age, sex, baseline left ventricular function, medication usage, and indication for study. The incidence of right coronary artery disease was identical in the three groups, as was the incidence of left ventricular functional abnormalities with exercise. Patients with proximal right coronary artery disease were more likely to have reduced left ventricular ejection fraction and more extensive coronary artery disease than those without disease at this site. We conclude that: (1) analysis of rest and exercise right ventricular function does not allow prediction of coronary anatomy in an unselected group of patients; (2) normal right ventricular function with exercise is compatible with extensive coronary artery disease, including proximal right coronary artery disease; and (3) abnormal exercise right ventricular function may be due to exertional left ventricular dysfunction in the absence of proximal right coronary artery disease.

Cardiac Catheterization↗
PubMed1988

Resting energy expenditure, body composition, and excess weight in the obese.

This study investigated differences between measured and predicted resting energy expenditure (REE) in 80 women who averaged 104.6 kg in weight and were 49 kg and 88% overweight. Body composition analysis showed that 68% of the excess weight was fat and 32% was fat-free mass (FFM). Normalized for height, total body potassium (TBK) was 113 +/- 15% and total body water (TBW) was 133 +/- 21% of values in nonobese controls. The health of the FFM, defined as the potassium content per kg of FFM, was 84 +/- 13% of normal. Measured and predicted REE were only modestly related (r = +.59), and only 59% of measured REEs were within 10% of predicted values. A stepwise multiple regression indicated that weight was the single best predictor of measured REE and that the size of the FFM made a significantly greater contribution to REE than did the size of the fat mass. Commonly used equations for the prediction of REE are not appropriate for moderately or severely obese patients. Caloric prescription for weight reduction must be tailored to individuals rather than recommending the same caloric intake to persons with varying metabolic rates.

Adipose Tissue↗
PubMed1988

Body fat deposition in adult obese women. I. Patterns of fat distribution.

Fat patterning was studied in a sample of 76 obese women before and after weight reduction by principal components analysis. Circumferences were selected as variables rather than skinfolds because circumferences correlated more highly with body composition determined either by total body water or total body potassium. A separate sample of 136 males and females, measured once, was employed to validate the results. The validation sample yielded similar findings. Two significant components were found, the first contrasting upper and lower fatness and the second trunk and extremity fatness. Waist circumference was the best predictor of upper-body fat patterning. For the lower body, thigh circumference loaded more highly than did the iliac crest circumference. Arm circumference did not contribute significantly to upper-lower fat patterning.

Adipose Tissue↗
PubMed1988

Body fat deposition in adult obese women. II. Changes in fat distribution accompanying weight reduction.

This study examined changes in body fat distribution in 68 women who lost an average of 12.3 kg from an initial weight of 103.6 kg. Weight reduction was accompanied by a small but statistically significant reduction of 1.2% in the waist-to-hip ratio, suggestive of a reduction in upper-body obesity. Subjects with greater upper-body obesity tended to achieve greater reductions in the waist-to-hip ratio. Changes in five circumference measures were highly correlated with losses of fat and showed that subjects with lower-body obesity tended to lose large amounts of fat from both their upper and lower fat depots while subjects with upper-body obesity lost fat primarily from their upper depots. Women with lower-body obesity tended to lose more total body fat than did women with upper body obesity (r = -0.26, p less than 0.04).

Adipose Tissue↗
PubMed1988

Bilateral upper lobe Pneumocystis carinii pneumonia in a patient receiving inhaled pentamidine prophylaxis.

A 46-year-old man with AIDS, receiving inhaled pentamidine for Pneumocystis carinii pneumonia (PCP) prophylaxis, developed bilateral upper lobe infiltrates. Bronchoalveolar lavage confirmed the diagnosis of PCP. Therapy with intravenous trimethoprim-sulfamethoxazole (TMP-SMX) was begun, with gradual resolution of these infiltrates noted. An explanation for the development of upper lobe PCP, despite aerosol chemoprophylaxis, is presented and emphasizes the importance of aerosol particle size (and therefore of nebulizer type) on the distribution of inhaled pentamidine.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Obesity and serum lipids: an evaluation of the relative contribution of body fat and fat distribution to lipid levels.

The association of obesity and hyperlipidemia does not mean that fatness per se is the primary determinant of the lipid abnormality. To evaluate the contribution of fatness to fasting levels of serum triglycerides (TG), LDL cholesterol (LDL-C), and HDL cholesterol (HDL-C), we analyzed data on 368 caucasian adults (286 women, 82 men) consecutively entering a weight control program. Although most subjects were overweight, the population represented a wide spectrum of body weights and lipid levels. Study variables included body fat mass (by total body water), fat free mass (FFM), body build (chest to height ratio), fat cell size and number (from bilateral buttock biopsy specimens), upper-lower body fat pattern by arm to thigh circumference ratio, central-peripheral fat pattern by subcapsular to triceps skinfold ratio, waist to hip ratio, and the presence or absence of diabetes. Our results concurred with previously noted correlations of body weight with TG (r = 0.29, P less than 0.0001) and with HDL-C (r = -0.28, P less than 0.0001) at least in the larger sample of women, but there was no significant correlation with LDL-C (r = -0.06). In order to evaluate the relative contribution of the various components of body composition and fat distribution to lipid levels, stepwise regression analyses were performed on the subgroups of women and men. Among women: TG level was predicted best by FFM, upper body fat pattern, age, and diabetes (explaining 30 percent of TG variance); LDL-C level was predicted by age only (explaining 12 percent of variance); and HDL-C level was predicted by body build only (8 percent). Among men: TG level was predicted best by central and upper body fat patterns and diabetes (31 percent of variance); LDL-C and HDL-C levels were not significantly predicted by any of the 11 study variables. These results, obtained from cross-sectional analysis of a predominantly obese sample, suggest that lipid levels may be more directly related to body fat pattern, fat free mass and body build than to body fatness itself.

Adipose Tissue↗
PubMed1986

Extra-abdominal pressure alters food intake, intragastric pressure, and gastric emptying rate.

Compression of the animal stomach gives rise to vagal discharges that could signal satiety. To test a noninvasive method of inducing compression of the human stomach, we first employed extra-abdominal pressure levels of 0, 10, and 20 Torr, counterbalanced for sequence, in six lean and obese subjects. A large blood pressure cuff was wrapped around the abdomen of the subject with the air bladder over the epigastrium. The bladder was inflated before ingestion of a liquid meal by the subject until satiated. Relative to 0 Torr, pressures of 10 and 20 Torr significantly reduced spontaneous food intake (P less than 0.03) without producing discomfort. In a second study, extra-abdominal pressure of 20 Torr also raised intragastric pressure by a mean of 5.5 Torr (P less than 0.03). In a third study, extra-abdominal pressure of 20 Torr did not alter gastric emptying rate during meal ingestion but ultimately enhanced emptying rate when this pressure was maintained for greater than 100 min after meal completion (P less than 0.01).

Abdomen↗
PubMed1986

Serum insulin and blood pressure in an obese population.

Serum insulin has been implicated as a determinant of blood pressure (BP) level in obese hypertensive individuals. We examined the relationships among fasting insulin, mean arterial pressure (MAP), body composition, and fat distribution in 204 subjects unselected for glucose tolerance. All met the criteria of taking no oral hypoglycemic agents, insulin or antihypertensive medications. 95 percent were considered obese and 78 percent were female. Mean age was 39 years (range 15-71), percent ideal body weight (IBW) 171 percent (109-332), BP 125/81 mmHg (80-181/50-110) and fasting insulin 44 microU/ml (4-196). Lean body mass (LBM) and body fat were measured by tritium dilution. The correlation coefficient between insulin and MAP was 0.32 (P less than 0.0001). Both insulin and MAP correlated highly with percentage IBW, percentage body fat, fat mass, LBM, body build and upper fat pattern. Controlling for these variables simultaneously eliminated the association between insulin and BP. By contrast, the correlations between MAP and measures of body composition and fat distribution retained significance after controlling for insulin level. These findings suggest that measures of body composition and fat distribution have a relationship with BP that is not entirely accounted for by serum insulin level, and the relationship between serum insulin and BP is indirect and largely accounted for by their mutual association with measures of body composition and fat distribution.

Adipose Tissue↗