Biomedical subjects

J C Thornton

Publications and source records attributed to J C Thornton.

At least 37 records · Page 2Linked to original sources

PubMed1996

A direct measure of satiety disturbance in patients with bulimia nervosa.

To determine whether patients with bulimia nervosa (BN) experience the development of satiety during a meal differently than control subjects, a novel laboratory meal procedure was employed. Eleven women with BN and 11 women without eating disorders consumed a yogurt shake meal after being instructed to binge. After each 75-g increment consumed, the subjects were signaled by a tone to fill out a questionnaire on which they were asked to rate various sensations on visual analog scales. The sensations included "Fullness", "Hunger", "Desire" for a favorite food, "Pleasantness" of consuming the shake, "Sickness", and having "Enough" to consume. Although patients, before purging, consumed significantly more food than the controls, who did not purge (1597 +/- 626.5 g vs. 1004 +/- 362.5 g, mean +/- SD), their final questionnaire ratings were not significantly different from the controls' ratings. Patients ate significantly more than the controls before reaching 50% of their range of "Hunger" rating and 75% of their "Full", "Desire", "Sick", and "Enough" rating ranges. The patients also ate significantly more than the controls between 75% and 100% of their "Hunger" rating range. These data suggest that one possible mechanism for overeating in patients with BN may be their failure to perceive or respond as normal subjects do to the range of sensations associated with satiety. Collecting ratings as a function of intake may provide a method for assessing and studying eating disturbances in clinical populations.

Adult↗

PubMed1996

Reliability of in vivo neutron activation analysis for measuring body composition: comparisons with tracer dilution and dual-energy x-ray absorptiometry.

In vivo neutron activation (IVNA) analysis has the capacity to measure several total body elements in human subjects. Although it has been considered a criterion method for the past 3 decades, the reliability of IVNA analysis has been tested only in phantom calibrations. In 5 male weight-stable patients with AIDS, total body N, Ca, Cl, Na, P, and C were measured three times in 16 weeks at Brookhaven National Laboratory. With tracer dilution methods for total body water (TBW) by 3H2O and for extracellular water (ECW) by 35SO4 and NaBr, and dual-energy x-ray absorptiometry (DXA), total body calcium (TBCa) and fat percentage were measured within 2 weeks of IVNA measurements. For comparison, tracer dilution for TBW by D2O and ECW by NaBr, plus DXA measurements, were performed three times in 5 weight-stable healthy volunteers. The reliability of the IVNA technique was very high in patients with AIDS; it ranged from 0.99 for total body chloride (TBCI) to 0.84 for total body phosphorus (TBP), and it agreed with phantom calibration results in the literature. The reliability for measuring fat percentage and TBCa by DXA was similar in patients with AIDS and in healthy volunteers. Tracer dilution for measuring TBW by 3H2O in patients with AIDS and by D2O in healthy volunteers had a reliability score similar to those found with IVNA and DXA. The reliability scores for measuring ECW in patients with AIDS by 35SO4 and NaBr, 0.66 and 0.68, respectively, were the lowest among all measurements, whereas the reliability score for NaBr in healthy volunteers was 0.96, as with the other measurements.

Absorptiometry, Photon↗

PubMed1995

Bone mineral and body fat measurements by two absorptiometry systems: comparisons with neutron activation analysis.

In 185 adults (68 white and 31 black males, 66 white and 20 black females), total body bone mineral density and content and body fat% were measured by two dual energy X-ray absorptiometry (DXA) systems--Norland XR-26, software version 2.4, and Lunar DPX, software versions 3.4 and 3.6. In a subgroup of 18 males (10 white, 8 black), body fat% and total body calcium were also measured by in vivo neutron activation analysis (IVNA). For total body calcium, the DPX 3.4 system gave the highest (1239 g), IVNA the lowest (1195 g), and the XR-26 (1226 g) was not significantly different from the DPX 3.6 results. For fat%, the XR-26 system gave the highest estimate (23.5%), whereas measurements by the DPX 3.4 and 3.6 systems (17.4 and 18.2%) were similar to the IVNA measurements (18.3%). BMD and BMC measurements by the two DXA systems were highly correlated but significantly different for the entire studied population except in the case of BMC in black males.

Absorptiometry, Photon↗

PubMed1995

Prediction equations for balance measured as sway speed by head tracking with eyes open and closed.

OBJECTIVES: To provide prediction equations for balance measured as sway speed, a population of randomly selected subjects was used as a model. METHODS: 265 subjects were selected from voter registration rolls in Arizona and Louisiana, USA. For validation these predicted values were compared with observed values obtained from a second population in California, USA. RESULTS: Sway speed with eyes open as a natural logarithm was: 1n (open) = -0.248333 -0.009634 x age +0.000164 x age2 and sway speed with eyes closed was: 1n (closed) = -0.585707 -0.023074 x age +0.000315 x age2 + 0.038496 x height (cm) CONCLUSIONS: The natural logarithm of balance with the eyes open was related to age by both linear and quadratic functions. Additionally with the eyes closed balance was dependent on height. These equations can be used to predict performance of groups being studied for effects of noise and chemicals. To define abnormality of individual subjects the predicted value plus 1.5 SDs could be used.

Adolescent↗

PubMed1995

Do radiographic criteria for emphysema predict physiologic impairment?

OBJECTIVE: The functional consequences of pulmonary emphysema have been estimated from autopsy studies. This antemortem study correlates structure as assessed by criteria applied to chest radiographs and function in earlier disease. SUBJECTS AND METHODS: Four thousand one hundred seven male shipyard and construction workers had chest radiographs scored for asbestosis using International Labour Office criteria and for emphysema using five criteria: hyperlucent lung fields, low flat diaphragms on posteroanterior views, low flat diaphragms on lateral radiographs, a wide retrosternal space, and bullae. Total lung capacity (TLC) was measured by planimetry of radiographs and forced vital capacity (FVC) and flows by spirometry: TLC minus FVC equaled residual volume (RV). All were expressed as percentage of predicted (% pred) adjusted for height, age, and duration of cigarette smoking. Linear regression modeling examined the influence of each emphysema criterion on function measurements. RESULTS: Four hundred three (10.1%) of 4,107 men had two or more emphysema criteria and 24.5% had asbestosis. Prevalence of 2 criteria varied by smoking status and was present in 20% of current smokers, 7.5% of ex-smokers, and 2% of never smokers. The TLC % pred and RV/TLC increased and % pred of FEV1/FVC and FEF25-75, FEV1, and FVC decreased with increasing radiographic emphysema criteria. Forty-four (10%) had normal results of spirometry with two or more radiographic emphysema criteria. CONCLUSION: Impairment of airway function worsened with each additional radiographic criteria of emphysema. These criteria were more strongly associated with an increase in RV/TLC than an increase in TLC.

Asbestosis↗

PubMed1994

Asians have lower body mass index (BMI) but higher percent body fat than do whites: comparisons of anthropometric measurements.

We studied the correlations between body mass index (BMI) and percent body fat (fat%) measured by dual-photon absorptiometry (DPA) in 445 white and 242 Asian adults aged 18-94 y. In addition, comparisons in six circumferences and eight skinfold-thickness measurements between whites and Asians were made to explain the discrepancies. Although Asians had lower BMI, they were fatter than whites of both sexes. The correlations between fat% and BMI varied by BMI and sex and race. Comparisons in anthropometry show that Asians had more subcutaneous fat than did whites and had different fat distributions from whites. Asians had more upper-body subcutaneous fat than did whites. The magnitude of differences between the two races was greater in females than in males. Prediction equations developed for each sex and race, based on BMI alone, gave SEEs ranging from 4.4% to 5.7%. All were significantly improved to the range of 3.5-4.4% when age and several skinfold-thickness measurements were added.

Adipose Tissue↗

PubMed1994

The pulmonary artery catheter: a diagnostic adjunct for fat embolism syndrome.

Available objective tests for fat embolism are neither sensitive nor specific. We performed frozen-section analysis of blood aspirated from a pulmonary artery catheter in a trauma victim with fat embolism syndrome and found marked levels of pulmonary microvascular blood fat. The amount of fat detected in this patient with long bone fractures was higher than that observed in a pilot study of this technique in cardiopulmonary bypass patients. This technique provided diagnostic support of our clinical findings. The procedure may prove useful in patients with an equivocal diagnosis of fat embolism or when the cause of posttraumatic acute pulmonary insufficiency is unknown.

Aged↗

PubMed1993

Bone mineral density and mass in a cross-sectional study of white and Asian women.

The literature suggests that Asians have lower bone mineral density and mass than whites. It has been proposed that these differences may be due to differences in height, weight, and factors other than ethnicity, but no study has made the appropriate direct comparisons. We compared total-body bone mineral density and mass between Asian and white women while controlling for factors known to be associated with bone mineral density and mass. Measurements were made in 129 Asian (primarily of Chinese ancestry) and 274 white women. A subgroup was formed of women who did not have a history of alcoholism, premenopausal amenorrhea, kidney disease, estrogen use, birth control pill use, thyroid disease, steroid use, hysterectomy, or smoking. In both the main group and the subgroups, bone mineral mass was significantly lower in Asian than in white women, but after analysis of covariance with body weight, height, and age (or years since menopause) as covariates, the differences between ethnic groups disappeared, except in the large group of premenopausal women, in whom average bone mineral density in Asians actually exceeded (p < 0.04) that in whites. The data set was also searched for Asian-white pairs who matched on 17 characteristics related to bone mineral density and mass. In the resulting 16 matched pairs, bone mineral density and mass were not different between ethnic groups. Although Asian women have lower bone mineral mass than white women, when weight, height, and other factors are controlled, bone mineral density and mass do not differ between Asian and white women.

Absorptiometry, Photon↗

PubMed1993

Biological homogeneity and precision of measurement: the boundary conditions for normal in body composition.

For compartments most urgently important to clinical medicine we have satisfactory levels of measurement precision, and the clinical considerations now are the availability of the methods, and the collection of data for normal subjects. Our colleagues in physics and imaging will improve measurement precisions, but the work most needed is to refine the biological side of the measurement equation. Large numbers of measurements, carefully done with carefully calibrated and unchanging systems, exist only for the special case of measuring body calcium in women, in the large cohort of approximately 2,500 women, studied by Aloia and Cohn with neutron activation, and for body potassium, in these women, and in the larger numbers of diverse age, sex, race, and size in the Rosetta study in our laboratory. Can we benefit from the "orthogonal measurements" and "orthogonal physiologic constraints" approaches, in which triangulation is used to combine measurements from several techniques to establish upper-lower bounds estimates by different techniques, with convergence on a "best fit" result? We have noted that the intrinsic homeostatic mechanisms of the body function with great precision to control body temperature, osmotic and ionic concentrations in the water phase, hypertrophy of muscle with exercise, and remodeling of bone by stress. We consider it unlikely that the control mechanisms are more loosely hinged for such secondary parameters as K/FFM and bone density.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1993

Novel antigens expressed by Aeromonas salmonicida grown in vivo.

Virulent and avirulent Aeromonas salmonicida strains grown inside intraperitoneal implants in Rainbow trout (Oncorhynchus mykiss) were examined for unique antigen expression. Western blots (immunoblots), performed with immune rabbit serum raised against in vivo-grown cells, revealed several unique antigens. With the exception of lipopolysaccharide (LPS), these novel antigens were destroyed after proteinase K treatment. The majority of these antigens were not induced in vitro in response to either iron limitation or anaerobiosis. In addition, electron microscopy demonstrated the presence of a putative capsule on in vivo-grown cells. Purification and fractionation of this carbohydrate material from cells grown in carbon-rich synthetic media resulted in the isolation and separation of an antigenically distinct LPS not seen with cells grown in standard media. Antiserum raised against in vivo-grown cells recognized both this LPS and the typical LPS of A. salmonicida apparent in in vitro-grown cells. Antiserum raised against in vitro-grown cells recognized only the LPS expressed in vitro. Antiserum directed against in vivo-grown cells was approximately 10 times more sensitive than serum directed against in vitro-grown cells in detecting A. salmonicida in infected fish kidney tissue.

Aeromonas↗

PubMed1993

Aeromonas salmonicida grown in vivo.

The virulent fish pathogen Aeromonas salmonicida was rapidly killed in vivo when restricted inside a diffusion chamber implanted intraperitoneally in rainbow trout. After a period of regrowth, the survivors had acquired resistance to host-mediated bacteriolysis, phagocytosis, and oxidative killing, properties which were subsequently lost by growth in vitro. Resistance to bacteriolysis and phagocytosis was associated with a newly acquired capsular layer revealed by acidic polysaccharide staining and electron microscopy. This capsular layer shielded the underlying, regular surface array (S-layer) from immunogold labeling with a primary antibody to the S-layer protein. Resistance to oxidative killing was mediated by a mechanism not associated with the presence of the capsular layer. An attenuated vaccine strain of A. salmonicida grown in vivo failed to express the capsular layer. Consequently, the in vivo-grown cells of this attenuated strain remained as sensitive to bacteriolysis, and as avidly adherent to macrophages, as the in vitro-grown cells. The importance of these new virulence determinants and their relation to the known virulence factors of A. salmonicida are discussed.

Aeromonas↗

PubMed1993

Fate of the fish pathogen Aeromonas salmonicida in the peritoneal cavity of rainbow trout.

A model was developed to study the fate of the fish pathogen Aeromonas salmonicida in vivo, inside a specialized intraperitoneal chamber implanted in rainbow trout, Oncorhynchus mykiss. Although normally recalcitrant to lytic agents in vitro, owing to the presence of its regular surface array (S layer), A. salmonicida was rapidly killed in the peritoneal cavity by a host-derived, soluble lytic activity present in peritoneal fluid. Peritoneal fluid was also found to kill other bacteria and lyse various types of erythrocytes, but was particularly lytic to A. salmonicida. Intraperitoneal survival of injected (free) A. salmonicida cells was several orders of magnitude higher than survival of implanted (restrained) cells. Injected free cells could evade the lytic activity of peritoneal fluid because they readily spread, initiating lethal infections. One evasion strategy was envisioned to be the penetration of peritoneal and (or) tissue macrophages. In spite of the killing mechanisms of these phagocytic cells, A. salmonicida was still able to survive and even replicate inside head kidney macrophages, thereby supporting the notion of A. salmonicida as a facultatively intracellular pathogen. Intraperitoneal chambers in rainbow trout may constitute a valuable experimental tool for studying the in vivo fate of A. salmonicida, and perhaps of other fish pathogens as well.

Aeromonas↗

PubMed1992

Expiratory flows decreased in Los Angeles children from 1984 to 1987: is this evidence of effects of air pollution?

To estimate the effects of air pollution we measured expiratory flows and vital capacities in 556 Mexican-American Los Angeles children in 1984 and 251 in 1987. They included 106 who were measured in 1984 and 1987 and 145 measured only in 1987. Pulmonary function values were standardized for growth be expressing them as percentages of predicted (% pred) based on sex and height. In 1987 mean values for FEV1 and FEF25-75 were lower by 4.5% pred and 13.6% pred respectively (P < 0.001), while vital capacities were not different in 213 children tested as fifth graders in 1984 and 251 fifth grade children in 1987. For the 106 children tested at both sessions (in second grade in 1984 and in fifth grade in 1987) FVC was also not different but FEV1 was 2.0% pred lower (P < 0.06) and FEF25-75 was 7.0% pred lower (P < 0.001). For the 450 children tested only in 1984 and the 106 retested in 1987 there were no significant differences in mean values for FVC, FEV1, and FEF 25-75. Similarly there were no significant differences between the 1987 mean values for 145 children who were studied longitudinally were not different from the 1984 and 1987 cross-sectional cohorts. Across this interval FEV1 and midflows diminished but vital capacities did not. Airways obstruction worsened during children's residence in Los Angeles from 1984 to 1987 and this is probably due to air pollution.

Air Pollutants↗

PubMed1992

Body composition and surgical treatment of obesity. Effects of weight loss on fluid distribution.

Obesity is associated with absolute and relative expansion of the extracellular water compartment (ECW). The effects of substantial and prolonged weight reduction on body water distribution are unknown, however. The authors studied total body water (TBW) by tritiated water dilution, ECW by 35SO4 dilution, exchangeable sodium (Na(e)) by 24Na, and total body potassium (TBK) by 40K whole-body counting in 25 severely obese women (body mass index [BMI] = 48 +/- 7 kg.m-2, mean +/- standard deviation) aged 36 +/- 8 years before and at intervals after gastric restrictive (GR; n = 12) and malabsorptive (MA; n = 13) operations for obesity. Results are compared with a control group of 26 healthy normal-weight women (BMI = 21 +/- 2). Before operation, the obese patients had absolute elevations of all water compartments compared with controls, with significantly higher ratios of Na(e) to TBK (1.17 +/- 0.13 versus 0.91 +/- 0.10; p less than 0.05) and ECW to intracellular water (ICW) (E/I = 0.82 +/- 0.17 versus 0.63 +/- 0.06; p less than 0.05). After weight loss of 52 +/- 20 kg in MA and 47 +/- 19 kg in GR patients (nonsignificant between groups) to a stable level 22 +/- 8 months after operation, there were statistically significant reductions in TBW, ICW, TBK, and Na(e) in both groups, but a significant reduction in ECW only after GR. Adjusting for preoperative weight, duration of follow-up, and rate of weight loss, E/I was greater after MA than GR (1.09 +/- 0.25 versus 0.82 +/- 0.14; p less than 0.05). The elevated preoperative E/I ratio did not normalize with weight loss after surgery, and the response was related to the type of operation. The finding remains to be explained although the increased E/I after MA may reflect mild protein-calorie malnutrition not detectable in the blood. The persistence of elevated E/I with significant weight loss after GR might imply an intrinsic or irreversible imbalance of fluid distribution in obese patients.

Adult↗

PubMed1992

Predictive equations for total lung capacity and residual volume calculated from radiographs in a random sample of the Michigan population.

BACKGROUND: Published predicted values for total lung capacity and residual volume are often based on a small number of subjects and derive from different populations from predicted spirometric values. Equations from the only two large studies gave smaller predicted values for total lung capacity than the smaller studies. A large number of subjects have been studied from a population which has already provided predicted values for spirometry and transfer factor for carbon monoxide. METHODS: Total lung capacity was measured from standard posteroanterior and lateral chest radiographs and forced vital capacity by spirometry in a population sample of 771 subjects. Prediction equations were developed for total lung capacity (TLC), residual volume (RV) and RV/TLC in two groups--normal and total. Subjects with signs or symptoms of cardiopulmonary disease were combined with the normal subjects and equations for all subjects were also modelled. RESULTS: Prediction equations for TLC and RV in non-smoking normal men and women were square root transformations which included height and weight but not age. They included a coefficient for duration of smoking in current smokers. The predictive equation for RV/TLC included weight, age, age and duration of smoking for current smokers and ex-smokers of both sexes. For the total population the equations took the same form but the height coefficients and constants were slightly different. CONCLUSION: These population based prediction equations for TLC, RV and RV/TLC provide reference standards in a population that has provided reference standards for spirometry and single breath transfer factor for carbon monoxide.

Adult↗

PubMed1991

Prevalence of spirometric abnormalities in a representative sample of the population of Michigan.

A random sample of a large industrial state in the United States (Michigan) was studied via respiratory questionnaire, medical history, physical examination, and spirometry: 976 white adults performed a battery of spirometric tests (FVC, FEV1, FEV1/FVC and FEF25-75%). Using predictive equations derived from normal subjects in the survey and defining spirometric abnormality by the lower 95% confidence interval, prevalences of abnormality were greater in those who had a smoking history. When equations derived from normal non-smokers were used, as has been the general practice, 21.3% of men and 18.5% of women with a positive smoking history had an abnormal FEV1 and 26.7% and 17.8% an abnormal FEF25-75%, respectively. Although FVC is thought to be affected little by smoking, mean values were lower and prevalences of abnormal values higher in smokers. Prevalences are also shown using an adjustment for the effect of smoking and using conventional (percent of predicted value) definitions of spirometric abnormality. The prevalences of spirometric impairments in this cross section of a large state should be useful for comparison with other populations under study in North America.

Adult↗

PubMed1991

Surface-disorganized, attenuated mutants of Aeromonas salmonicida as furunculosis live vaccines.

A slow-growing, aminoglycoside-resistant mutant and a rapidly-growing pseudo-revertant were isolated from Aeromonas salmonicida, the causative agent of salmonid furunculosis. These mutants continued to elicit a variety of classical virulence factors associated with A. salmonicida pathogenesis. They differed morphologically from the wild-type and from one another with respect to A-layer organization, membrane antagonist sensitivity and particularly to aerobic metabolism. Both mutants were drastically altered in the architecture of the 2D crystalline surface array (A-layer), although both were similar to wild-type with respect to cell surface composition. The slow-growing, antibiotic-resistant mutant differed significantly from the wild-type by the apparent loss of virtually all aerobic metabolism; the pseudo-revertant had partially recovered the ability to aerobically metabolize certain carbon sources. Both mutants were avirulent and incapable of tissue persistence. The rapidly-growing, antibiotic-sensitive pseudo-revertant, when administered either intraperitoneally or by immersion, effectively protected salmonid fish from challenge by a heterologous virulent stain suggesting its candidature as a live, attenuated furunculosis vaccine.

Aeromonas↗

PubMed1991

Measuring body fat: calibrating the rulers. Intermethod comparisons in 389 normal Caucasian subjects.

A systematic study of 389 normal Caucasians stratified for sex and age compared all of the traditional methods for measuring fat: body water, underwater weighing, body potassium, and anthropometrics and the newer methods of dual-photon absorptiometry, bioimpedance analysis, and total body electrical conductivity. Measurements by all methods are highly intercorrelated, but methods differences show the population means for fat percent to range from 26 to 35% of body weight across eight methods. All methods show increasing fat (as % body weight) with age in both sexes but vary in secular slope. The goal of this report is to provide direct translations between each of the eight methods. Intermethod comparison equations are given as simple linear regressions by using each method both as dependent and independent variable for each sex, permitting translation for results by any method to any other.

Adipose Tissue↗