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Biomedical subjects

M C Steiner

Publications and source records attributed to M C Steiner.

13 recordsLinked to original sources
PubMed2005

Adenine nucleotide loss in the skeletal muscles during exercise in chronic obstructive pulmonary disease.

BACKGROUND: Skeletal muscle adenine nucleotide loss has been associated with fatigue during high intensity exercise in healthy subjects but has not been studied in patients with chronic obstructive pulmonary disease (COPD). Changes in adenine nucleotides and other metabolites in the skeletal muscles were measured in patients with COPD and age matched healthy volunteers by obtaining biopsy samples from the quadriceps muscle at rest and following a standardised exercise challenge. METHODS: Eighteen patients with COPD (mean (SD) forced expiratory volume in 1 second 38.1 (16.8)%) and eight age matched healthy controls were studied. Biopsy samples were taken from the vastus lateralis muscle at rest and immediately after a 5 minute constant workload cycle test performed at 80% peak work achieved during a maximal incremental cycle test performed previously. RESULTS: The absolute workload at which exercise was performed was substantially lower in the COPD group than in the controls (56.7 (15.9) W v 143.2 (26.3) W, p<0.01). Despite this, there was a significant loss of adenosine triphosphate (mean change 4.3 (95% CI -7.0 to -1.6), p<0.01) and accumulation of inosine monophosphate (2.03 (95% CI 0.64 to 3.42), p<0.01) during exercise in the COPD group that was similar to the control group (-4.8 (95% CI -9.7 to 0.08), p = 0.053 and 1.6 (95% CI 0.42 to 2.79), p<0.01, respectively). CONCLUSIONS: These findings indicate that the ATP demands of exercise were not met by resynthesis from oxidative and non-oxidative sources. This suggests that significant metabolic stress occurs in the skeletal muscles of COPD patients during whole body exercise at low absolute workloads similar to those required for activities of daily living.

Adenine Nucleotides↗
PubMed2003

Nutritional enhancement of exercise performance in chronic obstructive pulmonary disease: a randomised controlled trial.

BACKGROUND: Pulmonary rehabilitation is effective in improving exercise performance and health status in chronic obstructive pulmonary disease (COPD). However, the role of nutritional support in the enhancement of the benefits of exercise training has not been explored. A double blind, randomised, controlled trial of carbohydrate supplementation was undertaken in patients attending outpatient pulmonary rehabilitation. METHODS: 85 patients with COPD were randomised to receive a 570 kcal carbohydrate rich supplement or a non-nutritive placebo daily for the duration of a 7 week outpatient pulmonary rehabilitation programme. Primary outcome measures were peak and submaximal exercise performance using the shuttle walk tests. Changes in health status, body composition, muscle strength, and dietary macronutrient intake were also measured. RESULTS: Patients in both the supplement and placebo groups increased shuttle walking performance and health status significantly. There was no statistically significant difference between treatment groups in these outcomes. Patients receiving placebo lost weight whereas supplemented patients gained weight. In well nourished patients (BMI >19 kg/m(2)) improvement in incremental shuttle performance was significantly greater in the supplemented group (mean difference between groups: 27 (95% CI 1 to 53) m, p<0.05). Increases in incremental shuttle performance correlated with increases in total carbohydrate intake. CONCLUSIONS: When universally prescribed, carbohydrate supplementation does not enhance the rehabilitation of patients with COPD. This study suggests that exercise training results in negative energy balance that can be overcome by supplementation and that, in selected patients, this may improve the outcome of training. The finding of benefit in well nourished patients may suggest a role for nutritional supplementation beyond the treatment of weight loss in COPD.

Aged↗
PubMed2002

Bedside methods versus dual energy X-ray absorptiometry for body composition measurement in COPD.

The measurement of body composition is of value in the nutritional assessment of patients with chronic obstructive pulmonary disease (COPD). The purpose of the present study was to compare two bedside methods for the measurement of body composition using dual energy X-ray absorptiometry (DEXA) as a reference method. Fat-free mass (FFM) was measured using DEXA, bioelectric impedance analysis (BIA) and skinfold anthropometry (SFA) in a cohort of 85 COPD patients accepted for pulmonary rehabilitation. Patients whose body mass index was >30 were excluded. Relative to DEXA, BIA underestimated FFM, whereas it was overestimated by SFA. There was a systematic increase in bias with mean FFM for both DEXA versus BIA and DEXA versus SFA, but this was almost eliminated when results were expressed as FFM index. Significant sex differences in the bias of BIA and SFA measurements of FFM were found. Forty-two (49.4%) patients were identified as nutritionally depleted using DEXA. Compared to DEXA, the sensitivity for detecting nutritional depletion was 86 and 74% for BIA and SFA, respectively, and the specificity 88 and 98%, respectively. There are significant intermethod differences in the measurement of body composition in chronic obstructive pulmonary disease patients. The choice of measurement method will have implications for nutritional assessment in chronic obstructive pulmonary disease.

Absorptiometry, Photon↗
PubMed1997

A patient with classical Kaposi's sarcoma and angiosarcoma: bad luck or a common aetiology?

Classical Kaposi's sarcoma and angiosarcoma are rare malignant tumours arising from vascular tissue. However, they have distinct histological features and appear also to differ in their epidemiology and pathogenesis. We present the case history of a patient in whom both these tumours occurred simultaneously. The relationship between these events is discussed in the light of the new virus, human herpes virus 8.

Combined Modality Therapy↗
PubMed1980

Minimizing errors in intrapulmonary shunt calculations.

In 100 critically ill patients, intrapulmonary shunts (Qsp/Qt) calculated by assuming a carboxyhemoglobin (HbCO) of zero and a hemoglobin saturation (HbO2) derived from the Severinghaus nomogram were compared to shunts calculated utilizing measured values of HbCO and HbO2. The differences were statistically significant (p less than 0.001). These 100 patients had a mean Hb of 11.9 g/dl and a mean HbCO of 1.7%. Measured shunt calculations in 30 critically patients were prospectively compared with shunt calculations utilizing the mean assumed values derived from the 100 patients initially studies. No statistically significant differences occurred between these two shunts. It is, therefore, concluded that errors attributable to the common practice of assuming zero HbCO and deriving HbO2 from nomograms will produce falsely high calculated intrapulmonary shunt values in critically ill patients. It is, therefore, important to measure accurately HbCO and HbO2 concentrations when monitoring intrapulmonary shunting in critically ill patients. However, if such measurements cannot be obtained, utilization of an assumed value of 1.5% for HbCO and HbO2 nomogram values will minimize errors in the shunt calculation.

Carbon Dioxide↗
PubMed1980

Changes in intrapulmonary shunting with administration of 100 percent oxygen.

The effects of increasing the fractional concentration of oxygen in the inspired gas to 1.0 on intrapulmonary shunting (Qsp) was evaluated in 82 intubated cardiovascularly stable patients in intensive care, regardless of airway pressure therapy or preexistent pulmonary pathologic abnormalities. Intrapulmonary shunting following administration of 100 percent oxygen increased in 132 of 140 measurements, decreased in seven, and remained unchanged in one measurement. The direction of change of Qsp with 100 percent oxygen shows no correlation with either airway pressure therapy or preexisting pulmonary disease.

Adult↗
PubMed1978

A stable blood product for pH-blood-gas quality control.

We describe how to prepare, store, and use a hemolyzed blood product for simultaneous pH, pCO2, and pO2 quality control. Tonometry of the blood product with two oxygen and two carbon dioxide concentrations resulted in consistent and reproducible values during 38 weeks. The resulting pH values were consistent and reproducible, demonstrating the metabolic acid-base stability of the blood product. We conclude that the proper preparation, storage, and use of the product results in consistent, reproducible, and economical quality control for pH, pCO2 and pO2 blood measurements.

Blood Chemical Analysis↗