Creating a novel genetic diversity of Trichoderma afroharzianum by γ-radiation for xylanase-cellulase production

Creating novel sources of a microbial strain using induced mutation can increase enzyme production for industrial use. According to this, we have developed a mutant strain of Trichoderma afroharzianum by Co60 gamma irradiation. Trichoderma mutants were isolated from an optimum dose of 250 Gy. The qualitative and quantitative screening were used for evaluating their enzyme production and the DNA barcoding method was used to identify the best Trichoderma mutant isolates. The highest cellulase (exo-glucanase, endoglucanase, β-glucosidase, and total cellulase) and xylanase activities were observed in superior mutant isolates of Trichoderma afroharzianum NAS107-M44 and Trichoderma afroharzianum NAS107-M82, which is approximately 1.6-2.5 times higher than its parent strain, respectively. The electrophoretic pattern of proteins showed that the exo-glucanase I, endo-glucanase III, and the xylanase I enzymes hydrolyzed the corn bran, synergistically. Overall, gamma irradiation-induced mutation could be an expedient technique to access such superior mutants for the bioconversion of corn bran wastes.

Trichoderma harzianum as fungicide and symbiont: is it safe for human and animals?

Trichoderma species are considered as biological control agents against numerous phytopathogenic fungi. They are also helpful for plants as plant symbiont. This study aimed to identify harmful effects of Trichoderma in laboratory animals. In the first step, inhalation toxicity was studied. Six rats as control received a spray of bio-formulation without spores. Ten rats as treatment A received    1.00 × 106 colony-forming unit (CFU) of Trichoderma spores and ten rats as treatment B received 1.00 × 107 CFU per test of Trichoderma spores. The harmful effects of Trichoderma were obvious especially in the lungs, liver and kidney, and some blood parameters were abnormal. In the second step, we studied acute oral toxicity by gavage. Four rats as control received bio-formulation without spores. Six rats as treatment A received 1.00 × 106 CFU per test of Trichoderma spores. Six rats as treatment B received 1.00 × 107 CFU per test of Trichoderma spores. The harmful effects of Trichoderma were noticeable more in the liver and kidney tissues. For dermal toxicity study, two rabbits as control received bio-formulation without spores by rubbing on the surface of the skin. Treatment groups A and B received 1.00 × 106 and 1.00 × 107 CFU per test of Trichoderma spores, respectively (four rabbits for each group). The liver and kidney and some blood parameters were abnormal. Trichoderma has some harmful effects on tissues and organs and although it is a natural product, it should be used under cautions.

Use of X-Irradiations in Reducing the Waste of Aflatoxin-Contaminated Pistachios and Evaluation of the Physicochemical Properties of the Irradiated Product

This study investigates the effects of electron beam irradiation (0, 1, 2, 4, and 6 kGy) on Aspergillus flavus, aflatoxin B1 (AFB1), and the physicochemical properties of pistachios. The findings suggested that e-beam significantly reduced the spore population of A. flavus and the concentration of AFB1 at doses of 4 and 6 kGy. Three AFB1 degradation products were detected via LC-MS analysis and their structures were presented. Total phenolic content was improved at a dose of 2 kGy, while antioxidant activity was decreased in all treatments in both DPPH and ABTS assays. The chlorophyll and carotenoid content declined and the color indices changed, leading to a darker color. E-beam at a dose of 2 kGy raised the soluble protein levels and changed the intensity and pattern of protein bands. Irradiation doses of up to 6 kGy enhanced the content of malondialdehyde and total saturated fatty acids while leading to a decline in unsaturated fatty acids. The quality features were adversely affected at doses > 4 kGy. The findings suggest that as an alternative method, e-beam at doses ≥ 2 kGy can effectively decrease fungal load and aflatoxin B1 contamination, and e-beam application at doses ≤ 2 kGy can maintain the physicochemical attributes of pistachios to an acceptable extent.

The Role of Cell Wall Degrading Enzymes in Antagonistic Traits of Trichoderma virens Against Rhizoctonia solani

Background:

High antagonistic ability of different Trichoderma species against a diverse range of plant pathogenic fungi has led them to be used as a biological fungicide in agriculture. They can also promote plant growth, fertility, resistance to stress, and absorption of nutrients. They are also opportunistic and symbiotic pathogens, which can lead to the activation of plant defense mechanisms.

Objectives:

The aim of this present study was to investigate possible enhancement of lytic enzymes production and biocontrol activity of T. virens against Rhizoctonia solani through gamma radiation and to find the relationship between changes in lytic enzyme production and antagonistic activity of T. virens.

Material and Methods:

Dual culture conditions were used to evaluate the antagonistic effect of T. virens and its gamma mutants against R. solani. Then, their chitinase and cellulase activities were measured. For more detailed investigation of enzymes, densitometry pattern of the proteins was extracted from the T. virens wild-type and its mutants were obtained via SDS-polyacrylamide gel electrophoresis.

Results:

The mutant T.vi M₈, T. virens wild-type and mutant T.vi M₂₀ strains showed the maximum antagonistic effects against the pathogen, respectively. Data showed that the mutant T. vi M₈ reduced the growth of R. solani by 58 %. The mutants revealed significantly different (p<0.05) protein contents, chitinase and cellulase production (mg.mL^-1) and activity (U.mL-1) compared to the wild-type strain. The highest extracellular protein production in the supernatant of chitinase and cellulase TFM was observed for the T.vi M₁₁ and T.vi M₁₇ strains, respectively. The T.vi M₁₂ and wild-type strains secreted chitinase and cellulase significantly more than other strains did. Densitometry of SDS-PAGE gel bands indicated that both the amount and diversity of chitinase related proteins in the selected mutant (T. vi M₈) were far higher than those of the wild-type. The diversity of molecular weight of proteins extracted from the T. virens M₈ (20 proteins or bands) was very high compared to the wild-type (10 proteins) and mutant T.vi M₁₅ (2 proteins).

Conclusions:

Overall, there was a strong link between the diversity of various chitinase proteins and the antagonistic properties of the mutant M8.

Rheological behaviour of dextran sulfate solutions

The purpose of this research was to study the rheological behaviour of dextran sulfate solutions under different conditions. A PC controlled rotational viscometer with a cone and plate geometry equipped with a temperature controlled unit was used to measure apparent viscosity of dextran solutions at different temperatures (25, 40 and 60 oC) and concentrations (2, 5, 10 and 20%). Viscosity tests of dextran sulfate solutions were performed at a range of shear rates (8-230 1/s) and the rheological data were fitted using the Power Law equation to get consistency and flow behaviour indices. The results indicated that all dextran sulfate solutions showed Newtonian flow behaviour. The viscosity of dextran sulfate solutions was significantly affected by temperature, e.g. the viscosity of a 5% solution at 25, 40 and 60 oC was 16.7, 12.7 and 10.7 mPa.s, respectively.

Physiological responses during hypoglycaemia induced by regular human insulin or a novel human analogue, insulin glargine

AIM

Glargine, a product of recombinant technology, has different structural and physicochemical properties compared with native human insulin. We determined whether such differences are associated with alterations in the responses to hypoglycaemia induced by glargine.

METHODS

Nineteen adults (six healthy and 13 with type 1 diabetes) underwent a 5-h hyperinsulinaemic (2 mU/kg/min(-1)) stepped hypoglycaemic clamps (hourly targets of 4.7, 4.2, 3.6, 3.1 and 2.5 mmol/l, respectively) on two occasions using intravenous infusion of regular human insulin or glargine, in random sequence. Hypoglycaemic symptoms, counter-regulatory hormones and glucose disposal rates were assessed at intervals throughout the clamps. A 1-week 'wash out' period was observed between studies.

RESULTS

The peak total symptoms scores (mean +/- s.e.m.) at nadir blood glucose (2.5 mmol/1) were 18.83 +/- 2.68 (healthy) and 17.46 +/- 3.62 (diabetic) during regular insulin, and 18.50 +/- 3.20 (healthy) and 19.08 +/- 3.83 (diabetic) during glargine infusion. The peak epinephrine levels during hypoglycaemia were 767.8 +/- 140.4 pg/ml (regular insulin) and 608.8 +/- 129.9 pg/ml (glargine) among healthy subjects, and 332.5 +/- 54.8 pg/ml (regular insulin) and 321.8 +/- 67.4 pg/ml (glargine) in diabetic patients. Diabetic patients had blunted glucagon responses during hypoglycaemia with either insulin. Both insulins also elicited similar rates of glucose disposal.

CONCLUSIONS

We conclude that insulin glargine and regular human insulin elicit comparable symptomatic and counter-regulatory hormonal responses during hypoglycaemia in healthy or diabetic subjects, and induce similar rates of glucose disposal. Since glargine is designed for subcutaneous (s.c.) use, it is possible (though unlikely) that our findings obtained using an intravenous protocol could differ from responses to hypoglycaemia induced by the s.c. route.

Impaired leptin response to glucocorticoid as a chronic complication of diabetes

Leptin has anorectic, anti-obesity, and insulin-sensitizing properties. We recently reported subnormal responses to the leptin secretagogue dexamethasone in diabetes (DM). To determine whether this defect precedes or follows the occurrence of diabetes, we have studied 37 adults: 11 with type 2 DM diagnosed within 6 months prior to study, 16 with chronic (> or =20 years) DM, and 10 healthy controls. After baseline measurements, subjects ingested dexamethasone (4 mg), followed by blood sampling 16 and 40 h later. Nadir plasma cortisol levels (<2.5 mg/dl) occurred 16 h after dexamethasone ingestion in all study groups; this period of maximal biological action of dexamethasone was associated with peak plasma leptin levels. The peak dexamethasone-stimulated plasma leptin responses (% baseline, +/-SEM) were 188+/-18.7% among healthy controls, 180+/-13.8% among new DM patients, and 127+/-10.5% (P<0.01) in chronic DM patients. Following dexamethasone ingestion, plasma glucose remained stable in the control and new DM groups but increased by 240% in the chronic DM patients; in contrast, plasma insulin increased significantly in controls and new DM patients but not in patients with chronic DM. These results indicate that plasma leptin responses to secretagogue are preserved in newly diagnosed diabetes patients but markedly attenuated in patients with long-standing diabetes, who also were unable to augment insulin secretion during glucocorticoid treatment. Thus, defective glucocorticoid augmentation of plasma leptin, probably related to beta-cell failure, may be a novel chronic complication of diabetes. Theoretically, such a defect could contribute to the obesity and insulin resistance associated with diabetes.

Hormonal regulation of human leptin in vivo: effects of hydrocortisone and insulin

OBJECTIVE

To investigate the effects of continuous i.v. infusion of hydrocortisone or insulin on leptin secretion in humans.

SUBJECTS

Six, nonfasting healthy adults (four women, two men), aged (mean +/- s.e.m.) 36.6 +/- 1.7 y; body mass index (BMI) 27.6 +/- 0.9 kg/m2.

DESIGN

Randomized, placebo-controlled, cross-over study, with a 2-week 'wash-out' period.

INTERVENTIONS

Intravenous infusion of hydrocortisone (3.3 microg/(kg min)), insulin (1 mU/(kg min)) or normal saline (placebo) for 24 h.

MEASUREMENTS

Blood sampling every 1-2 h for measurement of glucose, insulin, cortisol and leptin; subcutaneous abdominal fat biopsy for determination of leptin mRNA expression.

RESULTS

Plasma cortisol increased to 50.0 +/- 0.4 microg/dl during hydrocortisone infusion, but was unaltered during saline or insulin infusion. The plasma insulin levels were: 28.5 +/- 4.7 microU/ml (placebo), 40.8 +/- 9.2 microU/ml (hydrocortisone, P=0.214), and 243 +/- 23.0 microU/ml (insulin, P=0.0002). Peak hyperleptinemia occurred after 16h of insulin and 20h of hydrocortisone infusion; peak/baseline plasma leptin levels (ng/ml) were 18.2 +/- 4.2/15.1 +/- 3.3 (placebo, P=0.056), 42.1 +/- 7.0/16.0 +/- 3.8 (hydrocortisone, + 163%, P= 0.008) and 30.2 +/- 4.3/16.6 +/- 2.7 (insulin, +83%, P= 0.024). Adipocyte leptin mRNA increased by 350% after the hydrocortisone infusion.

CONCLUSION

Hydrocortisone, a natural glucocorticoid, induces hyperleptinemia in vivo, with a potency greater than that of insulin. The interaction between glucocorticoids and leptin may be of metabolic significance in humans.

Basal and stimulated plasma leptin in diabetic subjects

OBJECTIVE

To determine whether leptin secretion is impaired in diabetes, we compared basal and stimulated plasma leptin levels in diabetic subjects and healthy controls.

RESEARCH METHODS AND PROCEDURES

Blood samples for assay of leptin and other hormones were obtained at baseline in 54 diabetic patients and 65 controls, and 8 hours, 16 hours, and 40 hours following ingestion of dexamethasone (4 mg) in 6 healthy and 12 controls. C-peptide status was defined as "negative" if < or =0.1 ng/mL or "positive" if > or =0.3 ng/mL, in fasting plasma.

RESULTS

Basal plasma leptin levels were 19.7+/-2.2 ng/mL in nondiabetic subjects, 13.4+/-1.5 ng/ml in C-peptide negative (n = 28) and 26.1+/-3.7 ng/mL in C-peptide positive (n = 26, p = 0.001) diabetic patients. Dexamethasone increased leptin levels of controls (n = 6) to 145+/-17% of baseline values at 8 hours (p = 0.03), 224+/-18% at 16 hours (p = 0.01), and 134+/-18% at 40 hours (p=0.05). The corresponding changes were 108+/-13%, 126+/-23%, and 98+/-16% in C-peptide negative (n=6), and 121+/-10%, 144+/-16% (p=0.03), and 147+/-23% (p=0.11) in C-peptide positive (n = 6) diabetic patients, respectively. The peak stimulated leptin levels were lower in the diabetic patients, compared with controls. Plasma insulin increased (p = 0.02) in controls, but not in the diabetic patients, following dexamethasone.

DISCUSSION

Although diabetic patients have normal plasma leptin levels under basal conditions, their leptin responses to glucocorticoid are impaired, probably because of the concomitant insulin secretory defect. A subnormal leptin secretory response could worsen obesity and insulin resistance in diabetes.

Reproducibility of fasting plasma leptin concentration in lean and obese humans

We determined the reproducibility of plasma leptin levels in 20 healthy subjects (10 men, 10 women; 10 lean, 10 obese) at stable body weight. Blood samples were obtained, after an overnight fast, between 0700 and 0800 on days 1, 2, 3, 4, 5, 12, 19, and 26. Body weights were recorded on the same days. Plasma leptin was measured using a specific radioimmunoassay. The mean +/- SE baseline body weights (kg) were 65.8 +/- 3.6 (lean) and 96.4 +/- 7.1 (obese). The body mass indices (BMI) were 22.9 +/- 2.8 kg/m2 (lean) and 32.7 +/- 2.2 kg/m2 (obese). The mean daily fasting plasma glucose level was 98.7 +/- 3.7 mg/dl. Baseline plasma leptin levels (ng/ml) were 5.3 +/- 0.75 in lean men, 14.9 +/- 4.6 in obese men, 11.2 +/- 2.8 in lean women, and 27.1 +/- 8.4 in obese women. Fasting leptin levels on days 2 to 26 were highly correlated with the baseline levels on day 1 (r2 = 0.9, P<0.0001). Body weights remained within 98%-102% of baseline, whereas intra-individual leptin levels fluctuated between 80% and 120% of baseline values, throughout the 26 days of study. We conclude that fasting plasma leptin levels are reproducible, with a maximum day-to-day variation of approximately 20%, in healthy, free-living, lean and obese persons who maintain a stable body weight.

Recombinant human insulin-like growth factor-I (IGF-I) therapy decreases plasma leptin concentration in patients with chronic renal insufficiency

OBJECTIVE

To determine the relationship between plasma leptin and insulin-like growth factor-I (IGF-I) levels in healthy subjects and patients with chronic renal insufficiency at baseline, and during administration of recombinant human IGF-I in the renal impaired patients.

SUBJECTS

20 healthy subjects (six men, 14 women, age: 42.7 +/- 3.2 y) and nine subjects with chronic renal insufficiency (five men, four women, age: 53.6 +/- 3.7 y).

INTERVENTION

Daily s.c. injection of recombinant human IGF-I (50 micrograms/kg) for 24 d.

MEASUREMENTS

Fasting plasma levels of leptin, IGF-I, growth hormone, C-peptide, glucagon and IGF binding proteins by specific radioimmunoassays at baseline in all subjects and serially during IGF-I therapy in the renal impaired subjects.

RESULTS

Baseline leptin levels were correlated with body mass index (BMI, R = 0.72, P = 0.0001) but not IGF-I levels (R = 0.02). During IGF-I therapy, plasma IGF-I levels increased from 128 +/- 17.4 ng/ml at baseline to 250 +/- 36.8 ng/ml on day 3 (P = 0.003) and 323 +/- 61.6 ng/ml on day 24 (P = 0.01), whereas leptin levels declined: 24.4 +/- 10.3 ng/ml (baseline), 19.5 +/- 6.2 ng/ml (day 3, P = 0.028), and 17.2 +/- 4.9 ng/ml (day 24, P = 0.05).

CONCLUSION

Basal plasma leptin and IGF-I levels are not correlated; however, chronic administration of recombinant IGF-I is associated with an early and sustained decrease in plasma leptin levels. IGF-I may have an inhibitory effect on leptin secretion in humans.

Effects of androgen administration in men with the AIDS wasting syndrome. A randomized, double-blind, placebo-controlled trial

BACKGROUND

Development of successful anabolic strategies to reverse the loss of lean body mass is of critical importance to increase survival in men with the AIDS wasting syndrome. Hypogonadism, an acquired endocrine deficiency state characterized by loss of testosterone, occurs in more than half of all men with advanced HIV disease. It is unknown whether testosterone deficiency contributes to the profound catabolic state and loss of lean body mass associated with the AIDS wasting syndrome.

OBJECTIVE

To investigate the effects of physiologic testosterone administration on body composition, exercise functional capacity, and quality of life in androgen-deficient men with the AIDS wasting syndrome.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

University medical center.

PATIENTS

51 HIV-positive men (age 42 +/- 8 years) with wasting (body weight < 90% of ideal body weight or weight loss > 10% of baseline weight) and a free testosterone level less than 42 pmol/L (normal range for men 18 to 49 years of age, 42 to 121 pmol/L [12.0 to 35.0 pg/mL]).

INTERVENTION

Patients were randomly assigned to receive testosterone enanthate, 300 mg, or placebo intramuscularly every 3 weeks for 6 months.

MEASUREMENTS

Change in fat-free mass was the primary end point. Secondary clinical end points were weight, lean body mass, muscle mass, exercise functional capacity, and change in perceived quality of life. Virologic variables were assessed by CD4 count and viral load.

RESULTS

Compared with patients who received placebo, testosterone-treated patients gained fat-free mass (-0.6 kg and 2.0 kg; P = 0.036), lean body mass (0.0 kg and 1.9 kg; P = 0.041), and muscle mass (-0.8 kg and 2.4 kg; P = 0.005). The changes in weight, fat mass, total-body water content, and exercise functional capacity did not significantly differ between the groups. Patients who received testosterone reported benefit from the treatment (P = 0.036), feeling better (P = 0.033), improved quality of life (P = 0.040), and improved appearance (P = 0.021). Testosterone was well tolerated in all patients.

CONCLUSIONS

Physiologic testosterone administration increases lean body mass and improves quality of life among androgen-deficient men with the AIDS wasting syndrome.

Effects of fasting and glucose infusion on basal and overnight leptin concentrations in normal-weight women

The plasma concentration of leptin is reduced in association with chronic energy restriction and weight loss in humans, but little is known about the acute effects of fasting and glucose infusion on leptin. In this study, plasma leptin, insulin, glucose, and fatty acid concentrations were measured daily in 14 healthy, normal-weight, female volunteers aged 24 +/- 4 y with a body mass index (kg/m2) of 24.2 +/- 3.6 during a 4-d fast. The mean plasma leptin concentration decreased by 54 +/- 8% with fasting (P = 0.0006, ANOVA). In a stepwise-regression model, the change in leptin concentration with fasting correlated most significantly with the change in insulin (R2 = 0.48, P = 0.0057) and to a lesser extent with the change in body fat by bioimpedance analysis (R2 = 0.19, P = 0.03). Plasma leptin concentrations measured every 20 min from 2000 to 0800 on the fourth night of the fast did not show a time-dependent rise. A continuous intravenous infusion of 5% glucose providing 1414 +/- 323 kJ/d (338 +/- 78 kcal/d) was begun after 4 d of fasting in seven subjects who continued to fast for an additional 6 d. Within 24 h of the glucose infusion, leptin concentrations increased significantly by 80 +/- 52% (P < 0.05). These data show the sensitivity of plasma leptin concentrations to small changes in energy supply and suggest a basic role of substrate metabolism in the short-term regulation of leptin.

Body composition and endocrine function in women with acquired immunodeficiency syndrome wasting

The acquired immunodeficiency syndrome (AIDS) wasting syndrome is a devastating complication of human immunodeficiency virus (HIV) infection characterized by progressive weight loss and severe inanition. In men, the wasting syndrome is characterized by a disproportionate decrease in lean body mass and relative fat sparing. In contrast, relatively little is known about the gender-specific changes in body composition that characterize AIDS wasting in women. Three groups of women were studied to determine body composition and hormonal changes with respect to stage of wasting [nonwasting (NW; weight >90% ideal body weight; weight loss <10% of preillness maximum; n = 12), early wasting (EW; weight >90% ideal body weight; weight loss >10% of preillness maximum; n = 10), and late wasting (LW; weight <90%; n = 9)] and compared with a control group of 12, healthy, age-matched women. Weight loss averaged 6 +/- 6% (NW), 15 +/- 6% (EW), and 20 +/- 8% (LW) in the three groups. Lean, fat, and muscle masses were determined by dual energy x-ray absorptiometry and urinary creatinine excretion. Subjects were 36 +/- 5 yr of age (mean +/- SD) with a CD4 cell count of 379 +/- 239 cells/mm3. The body mass index was 24.4 +/- 2.6 kg/m2 (NW), 22.2 +/- 1.2 kg/m2 (EW), 18.2 +/- 2.0 kg/m2 (LW), and 24.3 +/- 2.6 kg/m2 (controls; P < 0.01, NW vs. EW; P < 0.0001, NW vs. LW). Lean body mass indexed for height was 15.7 +/- 2.4 kg/m2 (NW), 14.8 +/- 2.0 kg/m2 (EW), and 13.7 +/- 1.2 kg/m2 (LW) and was decreased significantly only in the LW group (P < 0.05 vs. NW). Muscle mass was 96% (NW), 94% (EW), and 78% (LW) of that predicted for height (P < 0.05, NW vs. LW). In contrast, fat mass indexed for height was decreased significantly among patients in both the EW and LW groups [8.7 +/- 1.9 kg/m2 (NW), 6.5 +/- 1.9 kg/m2 (EW), and 3.7 +/- 1.4 kg/m2 (LW); P < 0.05, NW vs. EW; P < 0.001, NW vs. LW). Expressed as a percentage of the value in nonwasting HIV-positive controls (NW), the relative loss of fat was greater than the loss of lean mass with progressive degrees of wasting [EW, 25% vs. 6% (fat vs. lean); LW, 58% vs. 13%]. The prevalence of amenorrhea was 20% among study subjects [17% (NW), 10% (EW), and 38% (LW)]. The percent predicted muscle mass was significantly lower in subjects with amenorrhea (74 +/- 8%) compared to that in eumenorrheic HIV-positive subjects (94 +/- 4%; P < 0.05). Estradiol levels were lower among subjects with amenorrhea (17.6 +/- 21.8 pg/mL) compared to eumenorrheic HIV-positive (48.9 +/- 33.6 pg/mL) and control (68.3 +/- 47.6 pg/mL) subjects and did not correlate with body composition. Mean free testosterone, but not total testosterone, levels were decreased in subjects with EW and LW compared to those in age-matched healthy controls, but not compared with those in NW [0.9 +/- 0.6 ng/dL (NW), 0.7 +/- 0.4 ng/dL (EW), 0.6 +/- 0.3 ng/dL (LW), and 2.0 +/- 2.4 ng/dL (controls); P < 0.05, EW vs. controls and LW vs. controls] and correlated with muscle mass (r = 0.37; P < 0.05). The percentages of women with free testosterone levels below the age-adjusted normal range were 33% (NW), 50% (EW), and 66% (LW). Dehydroepiandrosterone sulfate levels were also low in the subjects with LW compared to those in the control group [98 +/- 85 microg/dL (NW), 102 +/- 53 microg/dL (EW), 55 +/- 46 microg/dL (LW), and 132 +/- 68 microg/dL (controls); P < 0.05 LW vs. controls] and were correlated highly with free testosterone levels (r = 0.73; P < 0.00001) and also with muscle mass (r = 0.48; P < 0.01). These data demonstrate that women lose significant lean body and muscle mass in the late stages of wasting. However, in contrast to men, women exhibit a progressive and disproportionate decrease in body fat relative to lean body mass at all stages of wasting, consistent with gender-specific effects in body composition in AIDS wasting. (ABSTRACT TRUNCATED)

Serum leptin levels in women with anorexia nervosa

Leptin is a protein encoded by the ob gene that is expressed in adipocytes and regulates eating behavior via central neuroendocrine mechanisms. Serum leptin levels have been shown to correlate with weight and percent body fat in normal and obese individuals; however, it is not known whether the regulation of leptin is normal below a critical threshold of body fat in chronic undernutrition. We investigated serum leptin levels in 22 women, aged 23 +/- 4 yr, with anorexia nervosa. Duration of disease, weight, BMI, percent body fat, and serum leptin levels were determined for each patient. Nutritional status was assessed further by caloric intake and measurement of insulin and insulin-like growth factor I (IGF-I) levels. Twenty-three healthy women, aged 23 +/- 4 yr, taking no medications, with normal menstrual function and body mass index (BMI) between 20-26 kg/m2 (mean, 23.7 +/- 1.7 kg/m2), served as a control population for comparison of leptin levels. Subjects with anorexia nervosa were low weight (BMI, 16.3 +/- 1.6 kg/m2; normal, 20-26 kg/m2) and exhibited a striking reduction in percent body fat (7 +/- 2%; normal, 20-30%). The mean serum leptin level was significantly decreased in subjects with anorexia nervosa compared with that in age- and sex-matched controls of normal body weight (5.6 +/- 3.7 vs. 19.1 +/- 8.1 ng/mL; P < 0.0001). Serum leptin levels were correlated highly with weight, as expressed either BMI (r = 0.66; P = 0.002) or percent ideal body weight (r = 0.68; P = 0.0005), body fat (r = 0.70; P = 0.0003), and IGF-I (r = 0.64; P = 0.001), but not with caloric intake or serum levels of estradiol or insulin in subjects with anorexia nervosa. The correlation between leptin and body fat was linear, with progressively lower, but detectable, leptin levels measured even in patients with less than 5% body fat, but was not significant when the effects of weight were taken into account. In contrast, the correlation between leptin and IGF-I remained significant when the effects of weight, body fat, and caloric intake were taken into account. In normal controls, leptin correlated with BMI (r = 0.55; P = 0.007) and IGF-I (r = 0.44; P < 0.05), but not with fat mass. These data demonstrate that serum leptin levels are reduced in association with low weight and percent body fat in subjects with anorexia nervosa compared to normal controls. Leptin levels correlate highly with weight, percent body fat, and IGF-I in subjects with anorexia nervosa, suggesting that the physiological regulation of leptin is maintained in relation to nutritional status even at an extreme of low weight and body fat.