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Biomedical subjects

A Duggan

Publications and source records attributed to A Duggan.

13 recordsLinked to original sources
PubMed1992

Prediction of the metabolic cost of walking with and without loads.

Measurement of the metabolic cost of walking inconveniences subjects, and requires skilled technical support and expensive equipment. These factors have stimulated interest in predictive equations. The present study assessed existing equations. Under each of 17 combinations of gradient (0-6%) and carried load (4.1-37.4 kg), 7-12 men undertook treadmill walking at 1.67 m/s. Measured oxygen consumption and respiratory exchange ratio were used to calculate metabolic rate (MRobserved). Metabolic rate was also predicted from the equation of Pandolf et al. (1977) (MRpandolf) and, where appropriate, from another five equations relating to walking without loads. MRobserved and MRpandolf did not differ significantly (p greater than 0.05) under any combination of gradient and load. The overall mean MRobserved and MRpandolf of 609 W and 602 W, respectively, also did not differ significantly (p greater than 0.05). These variables were highly correlated (r = 0.94) with a standard deviation about the prediction error of 47 W. For level walking without loads, the mean predictions from the equations of Pandolf et al. (1977) and Cotes and Meade (1960) did not differ significantly (p greater than 0.05) from the mean MRobserved of 428 Watts, but four other equations overestimated by 17-74 W. In conclusion, the Pandolf et al. (1977) equation has given good results across the range of combinations of load and gradient tested, and the errors are considered acceptable for most practical purposes.

Adult↗
PubMed1990

Hairy cell leukemia-associated antigen (HC2) is an activation antigen of several hemopoietic cell lineages, inducible on monocytes by IFN-gamma.

The HC2 Ag is defined by a mAb raised against leukemic B lymphocytes from a patient with hairy cell leukemia (HCL). This 60 to 70-kDa Ag was immunoprecipitated from EBV-transformed B lymphoblastoid cell lines, from HCL-B cells, from the HUT-102 T cell line infected with HTLVI, and from activated monocytes. A binding assay with radioiodinated Fab' anti-HC2 confirmed this cellular distribution of the Ag and demonstrated 500 to 3000 binding sites on resting T cells, 300 to 11,000 binding sites on non-T cells, less than 3000 binding sites on chronic lymphocytic leukemia B cells, and 29,000 to 223,000 binding sites on HCL-B cells. PMA plus anti-CD3 up-regulated HC2 expression on T cells and IFN-gamma up-regulated expression on monocytes. On B cells, EBV transformation may result in HC2 expression, and antibody to HC2 has been found to inhibit B cell differentiation and proliferation. The combined results suggest an important role for the HC2 membrane-associated Ag on cells responsible for the immune response.

Antibodies, Monoclonal↗
PubMed1990

Blood lactate at 12 km/h and vOBLA as predictors of run performance in non-endurance athletes.

Run velocity at the onset of blood lactate accumulation (vOBLA) has been reported to be highly correlated with performance in endurance runs. From capillary blood samples taken during incremental treadmill running, vOBLA and the blood lactate concentration at a run speed of 12 km/h (La12) were determined in a group of 11 men which excluded endurance athletes. The inter-relationships between these variables, 4-km run performance and maximal oxygen uptake (VO2max) were investigated. vOBLA and La12 were highly correlated with one another (r = -0.95). Mean 4-km run speed was found to be closely related to vOBLA (r = 0.86), La12 (r = -0.88) and VO2max (r = 0.86). Reproducibility of both vOBLA and La12 was found to be good; test and re-test scores were highly correlated (r greater than or equal to 0.93) and did not differ significantly (p greater than 0.05). The present study suggests that vOBLA may be a valid and reproducible predictor of run performance in individuals who are not endurance athletes. It was not, however, found to be better in these respects than La12, the measurement of which would be easier and less traumatic to the subject since it would require less blood sampling.

Adult↗
PubMed1990

Twenty-five years of residents: what and where are they now.

To evaluate the effectiveness of our program in meeting the subsequent career needs of our graduates and to describe their professional experiences as a microcosm of pediatrics, a survey was completed of the 419 pediatricians who had completed the Harriet Lane Residency Program at The Johns Hopkins Hospital between 1960 and 1984. Overall, the 326 respondents found the program to have been effective in the areas they deemed appropriate to be taught in residency years. In decreasing order, the chief resident, fellow house officers, and full-time faculty were rated to have had the greatest teaching effectiveness. The women respondents were less likely to be married (76% vs 89%), had fewer children on average (1.2 vs 2.31), missed more work, and were more likely to enter postresidency training (89% vs 78%) than the men. Of all respondents, 73% reported being certain of their career goals during residency and 77% of those reported a reasonable similarity with current positions. More than 93% reported being satisfied with their current careers, and 87% would still choose pediatrics. They are generally well reimbursed financially, with academician salaries matching those of private practitioners 10 years after completing residency and surpassing them, slightly, thereafter. This information provides much food for thought in preparing tomorrow's pediatricians.

Attitude of Health Personnel↗
PubMed1989

Immunoregulation and production of tumor necrosis factor alpha by human thymocytes.

We have provided evidence that tumor necrosis factor alpha (TNF-alpha) enhances the proliferation and the state of activation of human thymocytes cultured with concanavalin A or interleukin 2 (IL-2), as evidenced by an increase in the expression of the c-myc gene and the gene of the IL-2 receptor (alpha-chain, Tac antigen) and by the expression of Tac antigen on the cell surface. Our observations suggest that TNF-alpha interacts with IL-2 and with another factor(s) which is induced in the course of activation by concanavalin A, since the immunosuppressant drug cyclosporin A-, which inhibits thymocyte activation, prevents the effect of TNF-alpha on thymocytes activated with concanavalin A, whereas anti-Tac, which prevents the binding of IL-2 to its receptor without affecting the production of IL-2 or the expression of IL-2-specific mRNA, inhibits proliferation only partially. By contrast, anti-Tac inhibits the response to TNF-alpha of thymocytes induced with IL-2 completely. These observations show that TNF-alpha exerts a potentially important immunoregulatory effect in synergy with IL-2 on thymocytes, which could contribute to tumor rejection. In addition, we show that activated human thymocytes express the TNF-alpha gene and that the expression of this gene is inhibited by cyclosporin A and dexamethasone.

Cell Division↗
PubMed1989

Inhibition by chlorpromazine of lymphokine-specific mRNA expression in human thymocytes.

This study was designed to determine the effect of the phenothiazine chlorpromazine (CPZ) on the activation of human thymocytes. We provide evidence that CPZ inhibits the accumulation of mRNA specific for the lymphokines, interleukin 2, interferon-gamma, tumor necrosis factor alpha and the proto-oncogene c-myc; by contrast, the accumulation of mRNA specific for the alpha chain of the interleukin 2 receptor and the subsequent early expression of Tac antigen on the cell surface is not inhibited by CPZ. The inhibition of the expression of lymphokine-specific mRNA results in a decrease in interferon-gamma synthesis and in inhibition of thymocyte proliferation as determined by the incorporation of [3H]thymidine. In addition, we show that activation of protein kinase C (PKC) in human thymocytes by 12-O-tetradecanoyl phorbol 13-acetate (TPA) causes the phosphorylation of a protein of a molecular mass of approximately 75 kDa. The function of this protein is as yet not defined, but it is possible that it plays a role in the transduction of the signals to the nucleus which in turn elicit the expression of the genes coding for c-myc and for the lymphokines required for thymocyte activation. We also demonstrate that CPZ, like the immunosuppressant drug cyclosporin A does not inhibit the phosphorylation of the 75-kDa protein which is induced by the activation of PKC by TPA and does not affect phosphoinositide breakdown, indicating that it exerts its effect at a site distal to the activation of PKC. These observations demonstrate that CPZ has an immunoregulatory function in addition to its psychotropic activity.

Chlorpromazine↗
PubMed1987

Upper and lower body anaerobic power: comparison between biathletes and control subjects.

This study compared power outputs (PO) from both the upper body (UB) and lower body (LB) Wingate tests of anaerobic power between biathletes and control subjects. Ten biathletes (B) selected by the British Ski Federation for potential assignment to the British team and 13 control (C) subjects cranked or pedaled the same Bodyguard ergometer at maximal RPMs for 30 s against resistances of 2.94 and 4.41 J/rev/kg body weight (BW), respectively. POs were calculated in watts (W) and expressed as peak power (PP, highest 5-s interval), mean power (MP, the mean for 30 s), and power decrease (PD, difference between PP and lowest 5-s PO divided by time). Absolute PP and MP for both UB and LB did not differ between groups. A comparison of POs made relative to BW showed B to have higher values than C: 11.25 vs 10.25 W/kg for LB PP (P less than .05) and 9.21 vs 7.96 W/kg for LB MP (P less than .001). The data expressed relative to kg fat free mass (FFM) showed only MP to be significantly greater in B compared with C (P less than .001). Similar PO relationships were found for the UB where PP (P less than .01) and MP (P less than .001) expressed per kg BW and MP (P less than .001) expressed per kg FFM were higher for B than C. Concomitantly, PD was lower in B than C for both the UB (P less than .05) and LB (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

An evaluation of tests of anaerobic power.

The objectives of this study were to examine the relationships between two recently developed laboratory tests of anaerobic power (AnP) and to compare these tests to other measures of AnP. Fifteen male subjects, aged 20-34 years, performed: a 30-s maximal cycle ergometer test (Wingate test), a 60-s isokinetic knee extension test (isokinetic endurance test), a 50-m sprint, a 200-m sprint, and the Margaria stair-climb test. Significant correlations ranging from 0.52-0.76 were found between the Wingate and isokinetic endurance tests for peak and mean values of power and torque, respectively. Indices from both these tests also correlated significantly with the other tests of AnP. The best single index was mean power from the Wingate test, which had correlations of -0.79, -0.82, and 0.74 with the 50-m and 200-m sprint times and the Margaria test, respectively. The data suggest that both the Wingate and isokinetic endurance tests represent valid laboratory tests for evaluating high-intensity, short-term exercise in which the muscle is primarily dependent upon anaerobic processes for energy release.

Adult↗