Biomedical subjects

J C Thornton

Publications and source records attributed to J C Thornton.

At least 19 recordsLinked to original sources

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↗

PubMed1990

Cross-shift and chronic effects of stainless-steel welding related to internal dosimetry of chromium and nickel.

Ninety welders from a stainless-steel fabricating plant were studied by pulmonary function tests and serum and urine chromium and nickel levels, cross-sectionally, and 31 were compared across a Monday shift. They had welded for a mean of 11 years, mean age was 44 years, and mean smoking duration was 20 years in 62 current smokers. Baseline spirometric tests were significantly reduced: FVC to 95.4 mean percentage of predicted (pop), FEV1 to 94.5 pop, FEF25-75 to 85.9 pop, and FEFR75-85 to 74.8 pop. Current smokers had greater reductions in flow rates and FVC than nonsmokers even after adjustment of their predicted values for the effects of duration of smoking. Neither alveolar volume at 104.3 pop nor diffusing capacity for carbon monoxide (single breath) at 98.5 pop was reduced. There were no significant changes in pulmonary function measurements across a Monday workshift in 31 welders, but in seven men who welded stainless steel, levels of serum chromium (Cr) rose 66% from 1.9 +/- 2.1 micrograms/liter and urinary Cr increased 22%. Serum nickel levels rose only 7%, although they were elevated before shift, 1.1 +/- 0.4 micrograms/liter (compared with 0.21 +/- 0.20 micrograms/liter in controls), and urinary nickel levels did not increase. Eleven years of welding had reduced vital capacities and expiratory flows. Monday stainless-steel welding raised the serum and urine chromium levels (measures of internal dosimetry for exposure) but did not decrease pulmonary function values.

Adult↗

PubMed1989

Efficacy of a nonrestricted fat diet in patients with cystic fibrosis.

We sought to determine if an increased oral intake with a noninvasive nutrition program in patients with cystic fibrosis could influence growth, weight gain, and pulmonary function. Thirty-seven patients, aged 2 to 27 years, were instructed to consume a nonrestricted fat diet during an intervention period of 4 years. The results showed that patients increased the mean energy intake significantly to a level of more than 120% of the recommended daily allowance. The enhanced intake resulted in significant weight gain. Pulmonary function (forced expiratory flow 25%-75%) deteriorated during the 2-year preintervention period but stabilized during the 4-year intervention period. Both male and female patients were able to maintain their established height and weight scores during adolescence. The recommendation for a high-energy diet with no restrictions placed on the fat intake and the control of the steatorrhea by administration of an optimal enzyme dosage is supported by our data. Individualized nutritional counseling should be attempted before implementing invasive nutritional intervention programs.

Adolescent↗

PubMed1989

An examination of factors that could affect choice reaction time in histology technicians.

Histology technicians exposed to formaldehyde and solvents have symptoms and objective evidence of neurobehavioral impairment of memory, judgment, and equilibrium. Because reaction time has been prolonged in many groups of workers exposed to toxicants, choice reaction time was measured in 385 female formaldehyde and solvent-exposed histology technicians, and 79 unexposed female laboratory workers. Choice reaction time to a visual stimulus (CRT) is defined, for the purpose of this study, as the time required for discriminated cancellation of two different letters on a microcomputer screen by pressing the matching keys. Initial analysis showed that increases in age, years of cigarette smoking, and hours per day of formaldehyde exposure significantly lengthened CRT, but xylene-toluene exposure had no effect. Since duration of smoking and length of daily formaldehyde exposure were age related, multiple linear regression analysis of CRT was performed using them as independent variables. Increasing age was the only significant factor in lengthening CRT. However, in these female histology technicians, the second measurement one year later was 44 msec faster (p less than .04). The reason for improved performance is unclear, but it may be an effect of training encompassing familiarity, improved attention, or learning.

Environmental Exposure↗

PubMed1989

Choice (CRT) and simple reaction times (SRT) compared in laboratory technicians: factors influencing reaction times and a predictive model.

Choice reaction time (CRT) and simple reaction time (SRT) tests were administered to 151 female histology laboratory technicians to determine if occupational exposure to organic solvents and formaldehyde delayed either or both. The relationships between CRT and SRT latencies were evaluated using different testers, sequences of administration, and microcomputers. Formaldehyde exposure, cigarette smoking history, ethnicity, and alveolar CO levels did not significantly influence CRT and SRT. However, slightly different protocols did significantly affect SRT. A linear model demonstrated that logSRT (LSRT) and LogCRT (LCRT) were longer with increasing age, promising further clinical applications. It is concluded that both CRT and SRT measure some overlapping and some different neurologic pathways. Reaction times in large "normal" populations are needed to compare with groups exposed to potential neurotoxins.

Adult↗

PubMed1989

Respiratory symptoms and functional impairment from acute (cross-shift) exposure to welding gases and fumes.

One hundred forty-five male welders from a West Coast shipyard were studied cross-sectionally and across a Monday work shift by pulmonary function tests and a questionnaire. Ten years of welding was associated with chronic bronchitis in 23.3% of nonsmokers compared to 3.3% in male controls, shortness of breath in 31.5% of nonsmokers compared to 1.5% in controls, and chest pain or heaviness in 38.4% compared to 4.4% in controls. Men who welded aluminum but had never smoked had more frequent wheezing, chest tightness, phlegm, feverishness and fatigue than those welding mild (black) or stainless steel. There were no significant cross-shift effects from welding exposure on measurements of pulmonary function. Although baseline expiratory flows were reduced slightly when compared to Caucasian-predicted values, ethnic specific comparisons for the largest subgroup showed only that FEF25-75 was reduced to 92.9 percentage of predicted values. Diffusing capacities for carbon monoxide were significantly reduced as compared to referents. The pulmonary function values of 25 current smokers were indistinguishable from the 41 who had never smoked, which probably reflects their low consumption of cigarettes.

Acute Disease↗

PubMed1989

Pulmonary function in histology technicians compared with women from Michigan: effects of chronic low dose formaldehyde on a national sample of women.

Chronic workplace exposure to formaldehyde and solvents at low doses reduced pulmonary function in 280 non-smoker white women working as histology technicians. They were studied during national workshops at four United States cities for four years. Height and age adjusted comparisons of pulmonary function were made with women in a stratified random population sample of Michigan and with a selected subset of the population that was used to model predictive pulmonary equations for function. The major functional change in histology technicians was a steeper decrement in vital capacity and flows from age 20 to 60 by regression analysis than occurred in the modelled Michigan population. Furthermore non-smoking and currently smoking women studied at two sites had significantly lower flows than were found in the sample of Michigan women. There was no consistent effect of an aerosol bronchodilator on flows of women at the four sites. Diffusing capacity for carbon monoxide single breath and alveolar volume were below the comparison group of Michigan women only when tested at Washington DC.

Adult↗

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

Serial angiographic assessment of coronary artery obstruction and collateral flow in acute myocardial infarction. Report from the second Mount Sinai-New York University Reperfusion Trial.

In the Second Mt. Sinai-New York University Reperfusion Trial, in which change of ejection fraction was the primary end point, the following secondary end points were prospectively assessed by serial coronary angiography: patency of the infarct artery both before intervention and 10-14 days later, acute and delayed recanalization rates, presence or absence of collateral flow, and complication rates of acute interventional catheterization. We assigned 393 patients randomly to groups receiving acute cardiac catheterization and a double-blind intracoronary infusion of streptokinase (SK arm), both streptokinase and nitroglycerin (SK-NTG arm), nitroglycerin alone (NTG arm), or conventional therapy without acute catheterization (control arm). Prospective stratification was based on duration of infarct pain before randomization: group A, less than 2 hours; Group B, 2-12 hours. Baseline patency rates were comparable in patients studied within 6 hours (30%, 40 of 135) and those studied later (24%, 32 of 133). This finding refutes the hypothesis that spontaneous recanalization occurs frequently after 6 hours. The acute recanalization rates of the SK arm (60%, 40 of 67) and the SK-NTG arm (63%, 29 of 62) did not differ. During streptokinase infusion, more vessels recanalized in group A (81%, 22 of 27) than in group B (56%, 57 of 102) (p less than 0.01); this was due to a significant reduction of recanalization rates from 75% (48 of 64) to 45% (26 of 62) with treatment after 6 hours (p less than 0.01). Delayed recanalization, that is, patency at end point but not postintervention, was seen in 17% (17 of 100) of total occlusions treated with streptokinase. In group A, all total occlusions treated with streptokinase recanalized either acutely (20 of 22) or delayed (two of 22), whereas in group B, 23% (18 of 78) remained obstructed. The reocclusion rate in the SK arms was 17% (11 of 65). In the NTG arm, recanalization occurred during intervention in 4% (two of 47) and delayed in 45% (21 of 47). At end-point angiography, the patency rates of the NTG arm (62%, 41 of 66) and the control arm (58%, 36 of 62) were comparable; those of the SK arms were higher (75%, 105 of 140) (p less than 0.01). Total occlusion was associated with collateral flow in 33% (66 of 199) at baseline; the prevalence of collaterals did not increase with time to angiography, which indicates that they had developed before the index event.(ABSTRACT TRUNCATED AT 400 WORDS)

Angiography↗

PubMed1989

Cardiac surgery in septuagenarians: is there a difference in mortality and morbidity?

Open heart surgery is being performed with increased frequency in elderly patients. Results vary considerably probably as the profile of the surgical population changes. A comparison was established by means of univariate analysis between two consecutive series of 100 patients undergoing bypass grafting or valvular replacement. Group A patients were 70 years of age or older; group B patients were less than 65 years of age. Various clinical, operative, and postoperative parameters were monitored. A significant difference was found between the two groups. Elderly patients tended to be white, female, with poor left ventricular and renal function, had carotid or peripheral vascular disease, and new onset of symptoms. Fewer patients had single-vessel disease and received internal mammary artery grafts. Operative mortality rate was higher in group A subjects and postoperative neurologic complications were also more frequent in this group. Factors influencing operative mortality were the association between vascular disease, presence of left main coronary artery disease, and urgency of the procedure. The mortality rate was 17.2% in 29 patients with associated vascular disease and 4.8% (3/63) in those without vascular disease (p = 0.048). Operative mortality was 4.1% without left main coronary artery disease, 15% with left main coronary artery disease (p = 0.083), and 4% in 84 patients having elective operations versus 31.2% in patients having 16 emergency procedures (p = 0.001). Short-term follow-up revealed a higher late mortality rate in elderly subjects and suggested an increased incidence of early pulmonary embolus. Nevertheless, elective cardiac surgery may be safely performed in septuagenarians with an expected operative mortality rate under 5%.

Age Factors↗

PubMed1989

Coronary artery bypass grafting with saphenous vein.

Occlusion rate of the saphenous vein is around 12-20% during the 1st year and 2-4% annually for the next 4 or 5 years. Subsequently, this rate doubles, so that at 10 years, approximately 50% of grafts become occluded due to the occurrence of graft atherosclerosis. A similar percentage of patent grafts show atherosclerotic changes at the end of the 1st decade. Sequential vein grafts probably suffer the same fate although late follow-up is lacking. Reoperation is estimated to be 30% at 10 years, as judged by angiographic criteria. The operative risk of reoperation is at least double that of primary operation; symptomatic relief appears to be of shorter duration. Recent technical changes to better preserve medial and endothelial function and to pharmacologically inhibit platelet function may lead to longer duration of the venous conduit.

Coronary Artery Bypass↗

PubMed1988

Determinants and protective potential of coronary arterial collaterals as assessed by an angioplasty model.

Two indexes of collateral blood flow, the ratio of distal coronary occlusion pressure/aortic pressure (DCOP/Pao) and angiographic collateral class were determined during elective angioplasty in 36 patients with normal left ventricular function. The association between collateral indexes and 8 anatomic and clinical variables was assessed. A reduction in luminal diameter by greater than or equal to 70% predicted angiographically demonstrable collaterals with 100% specificity and 85% sensitivity. Lesion severity (stenosis) correlated with both collateral class and DCOP/Pao: DCOP/Pao = 2.8809 - 0.0729 X stenosis + 0.00049 X stenosis. The data suggest a quantitative relation between lesion severity and collateral development beyond a threshold value of 70% stenosis. Left ventricular ejection fraction during ischemia caused by balloon occlusion (EFo) was found to be primarily determined by lesion location; however, collateral flow modified EFo significantly. For mid-left anterior descending and right coronary artery: EFo = 59 + 26 X (DCOP/Pao); for proximal left anterior descending artery: EFo = 24 + 89 X (DCOP/Pao). A model predicting the hemodynamic and clinical consequences of abrupt coronary closure based on lesion location and severity was developed. In the second study phase, this model was tested retrospectively in a different group of 23 patients who experienced coronary occlusion as a complication of angioplasty. The data of both study phases suggest that left ventricular function and clinical outcome after abrupt coronary closure are determined by an interaction between location of the coronary artery obstruction and the amount of collateral flow. Lesion severity and the extent of functional impairment resulting from abrupt coronary closure are inversely related.

Angioplasty, Balloon↗

PubMed1988

Clinical respiratory abnormalities in Michigan. Prevalence by sex and smoking history in a representative sample of the adult population.

A stratified random sample of a large state (Michigan) was studied by respiratory questionnaire, medical history, and physical examination. Data were obtained on 1,169 white adults. The prevalence of chronic bronchitis and chronic wheezing varied with sex (greater in men) and smoking history (greatest in current smokers). The prevalence of chronic bronchitis varied depending on whether it was (1) defined simply as chronic production of sputum, (2) diagnosed by the examining physician, or (3) previously diagnosed by a physician. Dyspnea was more common in women; in men, it was least common in nonsmokers but was of similar prevalence in ex-smokers and current smokers. Angina was more commonly reported by women, but previously diagnosed heart attack was consistently more common in men. Wheezing was by far the most common physical sign, present in 5.1 percent of the total population and 9.2 percent of male current smokers. Clubbing and rales were each noted in 1.2 percent of the total population. The prevalences of clinical findings in this cross section of a large state should be useful for comparison with other populations.

Adolescent↗