| Unexplained weight loss is common in patients with chronic obstructive pulmonary disease ( COPD). Although the increase work of breathing in COPD could be partly responsible for excessive energy expenditure, this hypothesis is still controversial. In either case, it dose not by itself explain weight loss, and other mechanisms have been considered.Leptin , an adipocyte-derived hormone, plays an important role in an energy homeostasis by signaling the brain about the amount of adipose tissue stored in the body. After interaction with specific receptors located in the central nervous system and in peripheral tissues, leptin induces a complex response, including control of body weight and energy expenditure. Against this background, we conducted the present study to elucidate two questions . First, whether serum leptin levels are inappropriately increased in patients with COPD . Second, whether serum levels of leptin are related to those signals of nutrition and pulmonary function in patients with COPD.Methods1. Study population and divide groups;ninety patients with COPD were diagnosed according to the criteria of the China Medicine Society. Their irreversible chronic airflow obstructions were confirmed. Forty-eight age-matched healthy human were also studied as control subjects. These control subjects had no medical illnesses, had normal physical examinations , blood counts, chemistries, and showed no symptoms or signs of infection at the time of study.2. Measurement of the signal of nutrition;After an overnight fast, all subjects had anthropometric measurements. All subject were measured body height, body weight, BMI, % IBW, % CHI, ALB, LYM and the circumferences of neck, chest, coelia . Informed consent was obtained from all subjects in the study.3. Pulmonary Function TestFVC and FEV1 were measured with standard spirometric techniques. The highest value from at least three spirometric maneuvers was used.4. Determination of Serum Leptin LevelsBlood samples were drawn between 8:00 and 9; 00 A. M. from subjects who had been fasting since 8:00 P. M. the previous night. Both serum and plasma were separated from blood cells by centrifugation at 2,000 x g for 15 min. All samples were stored at refrigerator (-70 ). Serum leptin concentrations were measured in duplicate with a highly sensitive radioimmunoassay ( RIA) .5. Statistical AnalysisValues were expressed as mean SD, independent samples T test were used to analyze the data. The relations between continuous variables were evaluated with Spearman s rank correlation technique. Significance was determined at the 5% level. Statistical analysis was done with the Statview Statistical Package.Results1. The levels of leptin in the COPD patients were significantly lower than in the healthy controls (0.65 0.41ng/ml versus 1.04 0.95ng/ml; p <0.01).2. Patients with COPD had significantly lower BMI, IBW% , CHI% , LYM and ALB than did the control subjects.3. We found significant correlations between serum leptin levels and BMI( r = 0.463; p<0. 01) as weU as % CHI (r =0.543; p<0.01) in COPD patients. The circulating leptin levels did correlate well with BMI and % CHI but not with ALB or with LYM in the COPD patients. These data suggest that circulating leptin is regulated physiologically even in the presence of cachexia in patients with COPD.4. The condition of COPD patients were the more severe the more low in the serum leptin levels and the singles of nutrition. We found the serum leptin levels and the singles of nutrition did correlate well with FEV1/FVC.DiscussionRecently, cytokine-mediated derangements have begun to be considered as among the candidates responsible for cachexia in COPD patients. Leptin, an o-besity gene product, is known to play important roles in the control of body weight and energy expenditure. This study was done to evaluate serum leptin levels and the possible association between malnutrition and severe of the disease in the regulation of energy expenditure, body composition,... |
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