Low muscle mass is linked with presence of non-alcoholic fatty liver disease irrespective to central obesity: highlights from a prospective epidemiological study in Greece

Background/Introduction

The association between sarcopenia and nonalcoholic fatty liver (NAFL) is highlighted in recent epidemiological studies, although results remain inconsistent.

Purpose

This study aimed to examine the association of low skeletal muscle mass with NAFL as well as the potential mediating effect of waist circumference on the examined association.

Methods

At baseline, 3,042 participants from the Attica region of Greece were recruited. NAFL was assessed through hepatic steatosis index (HSI). Skeletal muscle mass index (SMI) was indirectly calculated using a standard validated procedure.

Results

Ranking from 1st to 3rd SMI tertiles NAFL rate was 45%, 33% and 22%, respectively (p<0.001). Multi-adjusted logistic regression analysis revealed that participants assigned in the 2nd (Odds Ratio (OR): 0.50, 95% Confidence Interval (95% CI): 0.41–0.61)) and 3rd SMI tertile had 50% and 76% (OR: 0.24, 95% CI: 0.19–0.29) lower likelihood to have NAFL compared with their 1st tertile counterparts. This association remained robust after multiple adjustments; however, significance was marginally lost, when waist circumference was added to the model. Subsequently, a multi-adjusted dose-response analysis between SMI and NAFL was performed in the total sample, as well as in the subcategories of normal and abnormal waist circumference. In the total sample, a significant inverse association between SMI and NAFL was observed [OR (per 2 points increase in SMI) = 0.94 (95% CI: 0.92–0.95); p=0.001]. When categorized by waist circumference, participants with moderate/high SMI and normal waist circumference had the lowest NAFL rates (24.3%). Those with low SMI and normal waist circumference and those with moderate/high SMI and abnormal waist circumference had similar rates of NAFL (47.4% and 50.3%, respectively; p=0.25). Participants with both low SMI and abnormal waist circumference presented the highest NAFL rate (60.5%), which was significantly higher compared with the rest subgroups (p<0.001). These findings were confirmed in multi-adjusted analysis to assess NAFL odds per case: participants with adnormal waist, [OR (per 2 points increase in SMI) = 0.97 (95% CI: 0.94–1.00)] vs. participants with normal waist [OR (per 2 points increase in SMI) = 0.89 (95% CI: 0.84–0.95)].

Conclusions

Increasing SMI was associated with lower rates of NAFL independently to abdominal obesity, whereas the two interact as key determinants of NAFL.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Hellenic Society of Cardiology

Non-alcoholic fatty liver disease, Mediterranean diet and 10-year cardiovascular disease incidence: the mediating role of adiponectin. Highlights from the ATTICA prospective (2002–2012) study

Background/Introduction

The most updated set of guidelines (EASL-EASD-EASO 2016) suggests Mediterranean diet as a promising dietary pattern for non-alcoholic fatty liver disease (NAFLD) management.

Purpose

The association between NAFLD and adherence to Mediterranean diet as well as their interaction on 10-year fatal/non fatal cardiovascular disease incidence were evaluated.

Methods

Study population included 1,514 men and 1,528 women (>18 years old) in our city in Greece, free of CVD recruited during the 2001–2002 period. Liver steatosis and fibrosis assessment indices were calculated at baseline and specific cut-offs were used to capture NAFLD. Level of adherence to Mediterranean diet was assessed through MedDietScore. National and international food databases were used to estimate total daily carbohydrate intake. The cut-off point of 35% of total daily energy intake was set to define low vs. high carbohydrate intake. Circulating adiponectin level was measured at baseline (4.0 (2.0) μg/mL).

Results

MedDietScore was inversely associated with NAFLD indices of both steatosis and fibrosis yet only in Triglycerides-Glucose index [Odds Ratio (OR)3rd vs. 1st MedDietScore tertile = 0.53, 95% Confidence Interval (95% CI) (0.29, 0.95)] persisted in multi-adjusted models including adjustments for metabolic syndrome components, energy intake and overall and central obesity. This was more evident in men (p for sex interaction = 0.03). The protective role of Mediterranean diet was retained irrespective to the total carbohydrate content; however, sex-based stratified analysis revealed that in woman subsample only Mediterranean diet with low carbohydrate content (i.e. <35%) had an independent protective role against NAFLD presence [OR3rd vs. 1st MedDietScore tertile = 0.79, 95% CI (0.40, 0.96)]. NAFLD predicted CVD [Hazard Ratio (HR) = 3.01, 95% CI (2.28, 3.95)] in crude model as well as in multi-adjusted model [HR=1.37, 95% CI (1.10, 2.10)]. NAFLD effect on CVD remained significant only in MedDietScore below median [HR=1.38, 95% CI (1.00, 1.93)] whereas it was essentially null [HR=1.00, 95% CI (0.38, 2.63)] among subjects with lower score. Mediation analysis revealed that adiponectin was the strongest mediator of the examined associations. In particular, per 1 mg/dL serum adiponectin about 21% lower likelihood to have NAFLD was observed. Stratified analysis using the median value of adiponectin level (4.1 mg/dL) revealed that the inverse association between Mediterranean diet and NAFLD reached the level of significance only in case of adiponectin levels over the median values (OR (3rd vs. 1st MedDietScore tertile) = 0.69 95% CI (0.35, 0.98)).

Conclusion

Beyond the inverse association between Mediterranean diet and NAFLD several novelties were revealed; low-carbohydrate Mediterranean diet was more protective against NAFLD in women while an adiponectin-related mechanism was revealed.

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): This work was supported by a research grant from Hellenic Atherosclerosis Society. The ATTICA study is supported by research grants from the Hellenic Cardiology Society [HCS2002] and the Hellenic Atherosclerosis Society [HAS2003]

Associations of maternal and cord blood adipokines with offspring adiposity in Project Viva: is there an interaction with child age?

OBJECTIVES

Higher leptin and lower adiponectin correlate with adult and childhood adiposity, but it is unclear how exposure to these adipokines during gestation relates to offspring growth. We aimed to investigate the relationships of maternal and cord adipokines with offspring adiposity across childhood to early adolescence, as well as interactions with child age.

METHODS

In mother-child pairs in the Project Viva cohort, we measured adipokines in mothers at second trimester (n=1106) and in cord blood at birth (n=657). We measured offspring adiposity indices at early childhood (mean 3.3±s.d. 0.3 years), mid-childhood (7.9±0.8 years) and early adolescence (13.2±0.9 years). We analyzed associations of maternal and cord adipokines with offspring longitudinal adiposity using a linear mixed model adjusting for pre-pregnancy body mass index (BMI), gestational weight gain (GWG), and other confounders.

RESULTS

Mothers with higher BMI and GWG had higher leptin. Offspring born to mothers with the highest vs lowest quartile of leptin had lower BMI z-score (-0.49 units, 95% confidence interval (CI):-0.72,-0.26), waist circumference (-2.6 cm, 95% CI: -3.7,-1.5) and sum of subscapular and triceps skinfolds (-2.8 mm, 95% CI: -4.1,-1.4) in early life. An interaction term between maternal leptin and child age was positive, suggesting that the associations between maternal leptin and child adiposity were not constant over time. Offspring born to mothers with lowest vs highest quartile of maternal adiponectin had lower early life adiposity (BMI z-score -0.27 units, 95% CI: -0.48,-0.05). Results were similar for cord leptin but not cord adiponectin.

CONCLUSIONS

Our findings showed higher maternal and cord leptin, and lower maternal adiponectin are associated with lower offspring adiposity from childhood to early adolescence, independent of maternal BMI and GWG. However, the strength of these associations was not constant over time.

Lipid and inflammatory biomarkers and kidney function decline in type 2 diabetes

AIMS/HYPOTHESIS

Potentially modifiable biomarkers may influence the decline in estimated GFR (eGFR), but few data are currently available in type 2 diabetic adults.

METHODS

We studied 516 women with type 2 diabetes in the Nurses' Health Study with data on lipid and inflammatory biomarkers from plasma collected in 1989 and plasma creatinine in samples collected in 1989 and 2000. An estimated GFR decline of >or=25% over 11 years was the outcome of interest.

RESULTS

Comparing the highest with the lowest quartile, soluble tumour necrosis factor receptor 2 (sTNFR-2) was independently associated with an eGFR decline of >or=25% (multivariate OR 5.81; 95% CI 2.90-11.65); this association was stronger in obese women (OR 16.76; 95% CI 4.69-59.90 for BMI >or=30 kg/m(2); OR 2.78, 95% CI 1.12-6.89 for BMI <30 kg/m(2); p for interaction = 0.02). No lipids (total cholesterol, LDL-cholesterol, HDL-cholesterol, non-HDL-cholesterol, triacylglycerols, lipoprotein(a), or apolipoprotein B) or other markers of inflammation (C-reactive protein, fibrinogen, E-selectin, intracellular cell adhesion molecule 1, leptin or adiponectin) were significantly associated with eGFR decline after multivariable adjustment.

CONCLUSIONS/INTERPRETATION

Elevated sTNFR-2 levels may be an important and potentially modifiable risk factor for eGFR decline in type 2 diabetes, especially in those with a BMI of >or=30 kg/m(2).

Impact of physical activity on insulin levels in breast cancer survivors

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Background: Accumulating data suggest that body weight and physical activity may affect breast cancer risk and outcomes. Biological mechanisms underlying these relationships are not clear. Studies have demonstrated that high levels of insulin, often seen in obese and sedentary individuals, are also associated with an increased risk of breast cancer recurrence and breast cancer-related death. We sought to analyze whether exercise lowers insulin levels in a population of breast cancer survivors. Methods: Inactive women with early stage breast cancer who had completed adjuvant treatment were randomized to a 16 week, mixed cardiovascular and strength training exercise intervention, or to a normal care control group. Target exercise goals included 2 supervised strength training sessions and 90 minutes of unsupervised cardiovascular exercise each week. Fasting insulin and glucose levels, as well as measurement of weight, body composition, and circumference at the waist and hip, were collected at baseline and after 16 weeks in both groups, and changes in these measures were assessed. Results: One hundred and one women were randomized. Comparison of changes in anthropometric measures are presented in Table 1 . Baseline insulin levels were similar in the 2 groups. After the 16-week exercise or control period, insulin levels decreased by 2.86 μIU/ml in the exercise group (p=0.03), and by 0.27 μIU/ml in the control group (p=0.65). A comparison of the change in insulin levels across time in the 2 groups approached statistical significance (p=0.07). There was also a trend toward improvements in insulin sensitivity in the exercise group (p=0.09), with no change seen in fasting glucose levels. Conclusions: Physical activity was associated with a decrease in insulin levels and in hip circumference in breast cancer survivors. The relationship between physical activity and breast cancer prognosis may be mediated, at least partially, through changes in insulin levels and/or changes in fat mass or deposition.

[Table: see text]

No significant financial relationships to disclose.

Estrogens, testosterone and sex hormone binding globulin in relation to liver cancer in men

OBJECTIVE

Liver disease in men has been associated with an imbalance of serum estradiol and testosterone. We have evaluated whether serum estradiol and testosterone levels are altered in male liver cancer patients as a result of a specific effect of the disease or because of the associated liver damage.

METHODS

We have performed a hospital-based case-control study in Greece. The study subjects were all men; 73 patients with hepatocellular carcinoma (HCC), 25 with metastatic liver cancer (MLC) patients and 111 control subjects. Serum estradiol, testosterone and sex hormone binding globulin (SHBG) levels were measured for each subject. Data were analyzed by multiple linear regression.

RESULTS

Mean serum estradiol levels were significantly higher among HCC patients as well as among patients with MLC compared to controls. Mean serum testosterone levels were significantly lower among HCC patients as well as among patients with MLC compared to controls. The mean SHBG levels did not differ significantly between the groups. After controlling for the degree of liver damage, the elevated serum estradiol and reduced serum testosterone levels among HCC and MLC patients were no longer significant.

CONCLUSIONS

Changes in sex steroid levels among patients with liver damage are due to the liver damage per se and not to specific disease processes.

Insulin-like growth factor binding protein-3 predicts survival from acute childhood leukemia

OBJECTIVE

To investigate whether the three principal components of the insulin-like growth factor (IGF) system, IGF-1, IGF-2 and IGF binding protein-3 (IGFBP-3), are associated with survival from childhood leukemia.

PATIENTS AND METHODS

116 children, 0--14 years old, with newly diagnosed and bone-marrow-biopsy-confirmed acute childhood leukemia between 1993 and 1996 were followed up until death or March 31, 1998. IGF-1, IGF-2 and IGFBP-3 were measured at diagnosis and clinical data, including presence of hepatosplenomegaly and number of white blood cells, were available.

RESULTS

After controlling for gender, age, indicators of clinical severity and the other measured components of the IGF system there was a statistically significant (p < 0.05) inverse association of IGFBP-3 with survival. An increment of one standard deviation in IGFBP-3 was associated with a 65% reduction of the death hazard among the children with leukemia. Neither IGF-1 nor IGF-2 was associated with survival in this data set.

CONCLUSION

The presented empirical evidence in conjunction with the fact that IGFBP-3 modulates IGF-1 and IGF-2 bioavailability and is likely to have proapoptotic effects makes this compound a plausible independent predictor of survival from childhood leukemia.

Decreased serum leptin in bulimia nervosa

The eating disorder bulimia nervosa has been associated with impaired satiety, decreased resting metabolic rate, and abnormal neuroendocrine regulation. Preclinical studies suggest that such alterations could be associated with impaired leptin function. Thus, the goal of this study was to assess whether leptin function is decreased in bulimia nervosa. Serum leptin levels measured in women with bulimia nervosa (n = 18) and in women who had maintained stable recovery from bulimia nervosa (n = 15) were compared with values in healthy female controls (n = 20). Subjects were studied during the follicular phase of their menstrual cycle after an overnight fast and bed rest. Baseline serum samples were analyzed for leptin concentration by RIA. Subject groups were matched for age and body weight. Analysis of covariance, adjusting for percent body fat, demonstrated abnormally low serum leptin levels in the bulimia nervosa group (P: = 0.02), with a trend toward an inverse correlation between frequency of binge episodes and serum leptin concentration (P: < 0.1). Additionally, the remitted patient group demonstrated abnormally low leptin values (P: = 0.01). These results are consistent with the hypothesis that decreased leptin function may be associated with alterations in eating patterns, metabolic rate, and neuroendocrine regulation in bulimia nervosa.

Endocrinologic and psychological effects of short-term dexamethasone in anorexia nervosa

Patients with anorexia nervosa (AN) have hyperactivity of their hypothalamic-pituitary-adrenal (HPA) axis, sometimes accompanied by elevations of cortisol. We examined whether the normal effects of short-term dexamethasone treatment upon HPA axis suppression and appetite stimulation are observed in these patients. Five young women with AN and ten healthy female controls received one week of high-dose oral dexamethasone (2 mg/m2/d) preceded and followed by hormonal evaluation of sensitivity to glucocorticoids and psychological assessments. No differences in hormone levels of the HPA axis were observed between the two groups and control groups at baseline, after dexamethasone suppression, or following ACTH stimulation testing. However, fasting insulin levels were significantly lower in the AN group, both before and after dexamethasone therapy and their serum leptin levels were also significantly lower. The AN group had significantly lower scores on the Anorexia Nervosa Subtest and the Beck Depression Inventory after dexamethasone compared to controls. On daily analog scales, AN patients had higher anxiety scores while on dexamethasone. Normal sensitivity to glucocorticoids was observed in all parameters examined except for mild abnormalities in pancreatic beta-cell function. These data suggest that AN may represent a state of partial glucocorticoid resistance, as in other states of restricted food intake. Furthermore, these pilot data, including the effects of dexamethasone upon psychological outlook in AN, suggest that glucocorticoids are not an effective therapy for these patients.

Endogenous risk factors for childhood leukemia in relation to the IGF system (Greece). The Childhood Haematologists-Oncologists Group

OBJECTIVE

Insulin-like growth factor-1 (IGF-1) and its principal binding protein-3 (IGFBP-3) are central in the mediation of the effect of growth hormone, and the IGF system has been reported to play a role in the pathogenesis of childhood leukemia.

METHODS

To further evaluate the hypothesis connecting the IGF system to this disease, we have examined whether IGF-1 and IGFBP-3 are associated with the two main endogenous risk factors for childhood leukemia, namely gender and birth weight, since boys and heavier newborns are known to be at higher risk. IGF-1 and IGFBP-3 were measured under code in the serum of 118 apparently healthy children aged 0-14 years and the values of each of these components were regressed on age, gender and birth weight. Insulin-like growth factor-2 (IGF-2), as a dependent variable, and anemia during the corresponding pregnancy, as a predictor variable, were also evaluated for exploratory purposes.

RESULTS

In the total data set, IGF-1 was positively associated with birth weight (p = 0.0001), whereas girls had higher levels of IGFBP-3 (p = 0.01).

CONCLUSIONS

It appears that the associations of measured components of the IGF system with the examined risk factors for childhood leukemia are largely compatible with those that would have been expected, if this system played a role in the pathogenesis of childhood leukemia.

Insulin-like growth factor 1 in hepatocellular carcinoma and metastatic liver cancer in men

The insulin-like growth factor (IGF) axis has important autocrine, paracrine, and endocrine roles in the promotion of growth. Alterations of the IGF system have recently been implicated in the pathogenesis of several malignancies, but the relation to hepatocellular carcinoma (HCC) risk is unclear. To address this issue, we used an immunoradiometric assay to quantify IGF-1 levels in serum samples in a hospital-based, case-control study in Greece. The study subjects were all men and included 53 patients with HCC positive for hepatitis B and/or hepatitis C virus infections, 20 virus-negative HCC patients, 25 virus-negative patients with metastatic liver cancer (MLC), and 111 virus-negative control subjects. Data were analyzed by multiple linear regression, using IGF-1 as the dependent variable. The mean value of IGF-1 was 65.9 ng/ml among virus-positive HCC patients, 79.5 ng/ml among virus-negative HCC patients, 110.8 ng/ml among patients with MLC, and 174.7 ng/ml among hospital controls. After controlling for the degree of liver damage, as assessed by prothrombin time and serum albumin level, the reduction in IGF-1 level among HCC patients was found to be more than could be attributed to liver damage alone. This finding may have both diagnostic and pathophysiological implications.

Insulin-like growth factor 1 in hepatocellular carcinoma and metastatic liver cancer in men

The insulin-like growth factor (IGF) axis has important autocrine, paracrine, and endocrine roles in the promotion of growth. Alterations of the IGF system have recently been implicated in the pathogenesis of several malignancies, but the relation to hepatocellular carcinoma (HCC) risk is unclear. To address this issue, we used an immunoradiometric assay to quantify IGF-1 levels in serum samples in a hospital-based, case-control study in Greece. The study subjects were all men and included 53 patients with HCC positive for hepatitis B and/or hepatitis C virus infections, 20 virus-negative HCC patients, 25 virus-negative patients with metastatic liver cancer (MLC), and 111 virus-negative control subjects. Data were analyzed by multiple linear regression, using IGF-1 as the dependent variable. The mean value of IGF-1 was 65.9 ng/ml among virus-positive HCC patients, 79.5 ng/ml among virus-negative HCC patients, 110.8 ng/ml among patients with MLC, and 174.7 ng/ml among hospital controls. After controlling for the degree of liver damage, as assessed by prothrombin time and serum albumin level, the reduction in IGF-1 level among HCC patients was found to be more than could be attributed to liver damage alone. This finding may have both diagnostic and pathophysiological implications.

Effects of protease inhibitors on hyperglycemia, hyperlipidemia, and lipodystrophy: a 5-year cohort study

BACKGROUND

Although human immunodeficiency virus (HIV)-related morbidity and mortality rates in patients with advanced HIV infection who are treated with combination antiretroviral drugs have declined, significant metabolic adverse effects associated with these regimens have been increasingly recognized. However, since data from patients studied before and after initiation of protease inhibitor (PI) therapy are scant, the true effect of PIs on these metabolic changes remains unknown.

OBJECTIVES

To examine temporal trends in serum glucose and lipid levels after initiation of PI therapy, to assess whether changes are independent of virological response and improvement in disease severity, and to determine risk factors associated with the development of hyperglycemia, hyperlipidemia, and lipodystrophy.

METHODS

A 5-year historical cohort analysis in a population of 221 HIV-infected patients observed in the Infectious Diseases Clinic of a tertiary care center from October 1, 1993, through July 31, 1998. Clinical and laboratory data were retrieved from medical records and a computerized database. The main outcome measure was the incidence of hyperglycemia, hypercholesterolemia, hypertriglyceridemia, and lipodystrophy. Adjusted incidence rate ratios (IRRs) were estimated by means of Poisson regression. In addition, mixed regression analyses were performed to examine effects of PIs on serum lipid and glucose levels, modeled as continuous outcomes.

RESULTS

The cumulative incidence of new-onset hyperglycemia, hypercholesterolemia, hypertriglyceridemia, and lipodystrophy was 5%, 24%, 19%, and 13%, respectively. Most of these events occurred after initiation of PI therapy. Protease inhibitors were independently associated with hyperglycemia (adjusted IRR, 5.0; 95% confidence interval [CI], 1. 3-19.4), hypercholesterolemia (adjusted IRR, 2.8; 95% CI, 1.5-5.2), hypertriglyceridemia (adjusted IRR, 6.1; 95% CI, 3.1-11.7), and lipodystrophy (adjusted IRR, 5.1; 95% CI, 1.9-13.9). Anabolic steroids and psychotropic medications were also associated with lipodystrophy. Inclusion of potential intermediate variables (eg, virological suppression and increase in body weight) did not reduce the magnitude of the association with PIs. The association between hypertriglyceridemia and ritonavir was stronger than for other PIs (Wald test, P=.02). In contrast, the incidence of hyperglycemia, hypercholesterolemia, and lipodystrophy did not vary significantly across different PIs. Longitudinal mixed models confirmed that serum lipid levels were more substantially affected by antiretroviral therapy, particularly PIs, than serum glucose levels. Similarly, controlling for surrogate markers did not abolish the strong association between PIs and increase in serum lipid levels.

CONCLUSION

We found an independent association between PI use and hyperglycemia, hyperlipidemia, and lipodystrophy that is not explained by the antiviral and therapeutic effect of PIs.

Insulin-like growth factor 1 in hepatocellular carcinoma and metastatic liver cancer in men

The insulin-like growth factor (IGF) axis has important autocrine, paracrine, and endocrine roles in the promotion of growth. Alterations of the IGF system have recently been implicated in the pathogenesis of several malignancies, but the relation to hepatocellular carcinoma (HCC) risk is unclear. To address this issue, we used an immunoradiometric assay to quantify IGF-1 levels in serum samples in a hospital-based, case-control study in Greece. The study subjects were all men and included 53 patients with HCC positive for hepatitis B and/or hepatitis C virus infections, 20 virus-negative HCC patients, 25 virus-negative patients with metastatic liver cancer (MLC), and 111 virus-negative control subjects. Data were analyzed by multiple linear regression, using IGF-1 as the dependent variable. The mean value of IGF-1 was 65.9 ng/ml among virus-positive HCC patients, 79.5 ng/ml among virus-negative HCC patients, 110.8 ng/ml among patients with MLC, and 174.7 ng/ml among hospital controls. After controlling for the degree of liver damage, as assessed by prothrombin time and serum albumin level, the reduction in IGF-1 level among HCC patients was found to be more than could be attributed to liver damage alone. This finding may have both diagnostic and pathophysiological implications.

IGF-I and IGF-II in relation to colorectal cancer

Recent data suggest that the IGF system plays an important role in the pathogenesis of several forms of human cancer, and there is evidence that IGFs acting in an autocrine and paracrine manner may also affect colorectal cancer risk. We have conducted a case-control study on the island of Crete, Greece, to examine the potential relation between circulating IGF-I and -II and their major binding protein (IGF-BP3), on the one hand, and colorectal cancer, on the other. IGF-I, IGF-II and IGF-BP3 were determined in the serum from 41 patients with colorectal cancer and 50 healthy controls; data were analyzed using unconditional multiple logistic regression, adjusting for age, gender, education, height and BMI, as well as mutually. Both IGF-I and IGF-II were positively, while IGF-BP3 was inversely, associated with risk for colorectal cancer, though none of these relations reached statistical significance. However, individuals with IGF-I and -II values in the upper 2 tertiles of the respective distributions had a significantly elevated odds ratio for colorectal cancer (OR = 5.2, 95% confidence interval 1.0-26.8) compared with those in the lower tertile in both distributions. Our results provide evidence that high levels of circulating IGF-I and -II might be associated with colorectal cancer.

Age, sex, and smoking are predictors of circulating insulin-like growth factor 1 and insulin-like growth factor-binding protein 3

PURPOSE

Insulin-like growth factor (IGF-1) and its major binding protein (IGF-BP3) have recently been implicated in the pathogenesis of several malignancies. However, anthropometric and lifestyle predictors of these hormones have not been elucidated. Here we report the results of a cross-sectional study.

SUBJECTS AND METHODS

This cross-sectional study examines the relationship of a series of epidemiologic parameters (age, sex, height, body mass index, smoking, alcohol consumption, and coffee drinking) with IGF-1 and IGF-BP3 in a sample of 130 healthy adults.

RESULTS

We observed that serum levels of IGF-1 are higher, whereas levels of IGF-BP3 are lower, in men than in women. In addition, serum levels of IGF-1 are independently and negatively associated with age and positively associated with pack-year history of smoking. Finally, serum levels of IGF-BP3 are independently and negatively associated with the number of cigarettes smoked per day or pack-year history of smoking.

CONCLUSION

Age, sex, and smoking are independent predictors of IGF-1 and/or IGF-BP3. The influence of these epidemiologic variables on the pathogenesis of disease states associated with IGF-1 and IGF-BP3 warrants further exploration.

Insulin-like growth factor-I and binding protein-3 in relation to childhood leukaemia

The aetiology of most cases of childhood leukaemia remains unknown, but several studies have indicated that increased birthweight and height are risk factors for the disease. Since insulin-like growth factor-I (IGF-I) mediates the effect of growth hormone and has been positively associated with prostate cancer, we have evaluated the role of this hormone and its principal binding protein, IGFBP-3, in the aetiology of childhood leukaemia. Incident cases of childhood leukaemia from those recorded by a national network of childhood oncologists were enrolled in our study. Controls were children hospitalised for acute conditions of no more than moderate severity with matching for gender, age and maternal place of residence. Blood measurements of IGF-I and IGFBP-3 were undertaken using commercially available radioimmunoassays. Serum IGF-I values decreased by about 1.7% per month, and the rate of decline was higher, though not significantly so, among cases (2.1% per month) than among controls (1.4%). There was no significant association between IGF-I and the likelihood of childhood leukaemia, but an increment of 1 microg/ml of IGFBP-3 was associated with a substantial and statistically significant reduction of childhood leukaemia by 28% (95% confidence interval 7% to 45%). Because IGFBP-3 is essentially a binding protein, we interpret our findings as indicating that bioavailable IGF-I may play an important role in the aetiology of childhood leukaemia. The much smaller quantities and the inherent instability of IGF-I in the blood in comparison to those of IGFBP-3 are likely to hinder documentation of an underlying positive association of IGF-I with the disease.

Sex differences in circulating human leptin pulse amplitude: clinical implications

Leptin, a product of fat cells, provides a signal of nutritional status to the central nervous system. Leptin concentrations have ultradian and diurnal fluctuations. We conducted this study to assess sex differences in the levels of organization of frequently sampled leptin concentrations in healthy, normal weight women and men. Leptin levels were sampled every 7 min for 24 h in 14 healthy, normal weight individuals (6 women and 8 men). The 14 leptin time series containing a total of 2898 leptin measurements were assessed by 1) algorithms that characterize statistically significant pulsatility, 2) Spectral (Fourier) analysis, 3) analysis of time intervals and variability, and 4) approximate entropy. We found that frequently sampled plasma leptin concentrations have a 24-h profile that is numerically more than twice as high in women as in men, and leptin pulse amplitude is likewise more than twice as high in women. However, healthy men and women have nearly identical concentration-independent and frequency-related 24-h and ultradian patterns. Leptin concentrations have nonrandom fluctuations over 24 h, independent of their absolute value and underlying 24-h periodicity, that are similar in men and women. Ultradian periodicities detected by Fourier time series have similar values in men and women. The strongest distinction between the sexes in the level of organization of leptin concentration is not at the level of pulse organization or oscillation frequency, but, rather, in the mass or amount of leptin released (or removed) per unit time, indicating that women might be more resistant to the effects of leptin than men. Because leptin is clinically relevant to the regulation of body weight, future studies should examine whether the relative leptin resistance exhibited by women might contribute to their increased susceptibility to disorders whose pathophysiology involves dysregulation of food intake and body weight.

Synchronicity of frequently sampled, 24-h concentrations of circulating leptin, luteinizing hormone, and estradiol in healthy women

Leptin, an adipocyte hormone, is a trophic factor for the reproductive system; however, it is still unknown whether there is a dynamic relation between fluctuations in circulating leptin and hypothalamic-pituitary-ovarian (HPO) axis hormones. To test the hypothesis that fluctuations in plasma leptin concentrations are related to the levels of luteinizing hormone (LH) and estradiol, we sampled plasma from six healthy women every 7 min for 24 h during days 8-11 of the menstrual cycle. Cross-correlation analysis throughout the 24-h cycle revealed a relation between release patterns of leptin and LH, with a lag of 42-84 min but no significant cross-correlation between LH and estradiol. The ultradian fluctuations in leptin levels showed pattern synchrony with those of both LH and estradiol as determined by cross-approximate entropy (cross-ApEn). At night, as leptin levels rose to their peak, the pulsatility profiles of LH changed significantly and became synchronous with those of leptin. LH pulses were fewer, of longer duration, higher amplitude, and larger area than during the day. Moreover, the synchronicity of LH and leptin occurred late at night, at which time estradiol and leptin also exhibited significantly stronger pattern coupling than during the day. We propose that leptin may regulate the minute-to-minute oscillations in the levels of LH and estradiol, and that the nocturnal rise in leptin may determine the change in nocturnal LH profile in the mid-to-late follicular phase that precedes ovulation. This may explain the disruption of hypothalamic-pituitary-ovarian function that is characteristic of states of low leptin release, such as anorexia nervosa and cachexia.

The influence of smoking habits on thyroid gland volume: an ultrasonic approach

The effects of smoking habits on thyroid function, echo-texture (nodules and/or cysts) and thyroid gland volume were determined by using ultrasound and measuring serum Thyroxin (T4), Triiodothyronine (T3), Thyrotropin (TSH) and TPO antibodies (ab-TPO) in 189 healthy smokers and non-smokers, randomly selected (111 females and 78 males) among the employees of our hospital and their relatives. When the entire group of subjects was considered the mean ratio of thyroid gland volume/body weight was found to be significantly higher in male (P < 0.05) and female (P < 0.05) smokers compared with non-smokers. In female smokers, mean serum thyroid-stimulating hormone (TSH) was lower (P < 0.05) and the degree of smoking was positively correlated with the ratio of thyroid gland volume/body weight (P < 0.05). However, when the subjects with a family history of goitre in first degree relatives were excluded from our study (14 females and 9 males), no significant differences in mean ratio of thyroid volume/weight or TSH between the remaining smokers and non-smokers were detected. In both sexes, the correlation between the degree of smoking and thyroid volume, although positive, did not reach statistical significance. No difference in prevalence of abnormal echogenicity and echo-texture (nodules and cysts) between smokers and non-smokers was detected. It is concluded that smoking habits present a goitrogenic effect only in subjects with a family history of goitre but have no influence on thyroid gland texture.

Cerebrospinal fluid leptin in anorexia nervosa: correlation with nutritional status and potential role in resistance to weight gain

Studies in rodents have shown that leptin acts in the central nervous system to modulate food intake and energy metabolism. To evaluate the possible role of leptin in the weight loss of anorexia nervosa, this study compared cerebrospinal fluid (CSF) and plasma leptin concentrations in anorexic patients and controls. Subjects included 11 female patients with anorexia nervosa studied at low weight and after treatment, and 15 healthy female controls. Concentrations of leptin in blood and CSF were measured by RIA. Patients with anorexia nervosa, compared to controls, had decreased concentrations of leptin in CSF (98 +/- 26 vs. 160 +/- 58 pg/mL; P < 0.0005) and plasma (1.75 +/- 0.46 vs. 7.01 +/- 3.92 ng/mL; P < 0.005). The CSF to plasma leptin ratio, however, was higher for patients (0.060 +/- 0.023) than for controls (0.025 +/- 0.007; P < 0.0001). At posttreatment testing, although patients had not yet reached normal body weight, CSF and plasma leptin concentrations had increased to normal levels. These results demonstrate the dynamic changes in plasma and CSF leptin during positive energy balance in anorexia nervosa. The results further suggest that normalization of CSF leptin levels before full weight restoration during treatment of anorexic patients could contribute to resistance to weight gain and/or incomplete weight recovery.

Human leptin levels are pulsatile and inversely related to pituitary-adrenal function

Leptin communicates nutritional status to regulatory centers in the brain. Because peripheral leptin influences the activity of the highly pulsatile adrenal and gonadal axes, we sought to determine whether leptin levels in the blood are pulsatile. We measured circulating leptin levels every 7 minutes for 24 hours, in six healthy men, and found that total circulating leptin levels exhibited a pattern indicative of pulsatile release, with 32.0 +/- 1.5 pulses every 24 hours and a pulse duration of 32.8 +/- 1.6 minutes. We also show an inverse relation between rapid fluctuations in plasma levels of leptin and those of adrenocorticotropic hormone (ACTH) and cortisol that could not be accounted for on the basis of glucocorticoid suppression of leptin. As leptin levels are pulsatile, we propose that a key function of the CNS is regulated by a peripheral pulsatile signal. In a separate pilot study we compared leptin pulsatility in 414 plasma samples collected every 7 minutes for 24 hours from one obese woman and one normal-weight woman. We found that high leptin levels in the obese subject were due solely to increased leptin pulse height; all concentration-independent pulsatility parameters were almost identical in the two women. Leptin pulsatility therefore can be preserved in the obese.

Role of leptin in the neuroendocrine response to fasting

A total deficiency in or resistance to the protein leptin causes severe obesity. As leptin levels rise with increasing adiposity in rodents and man, it is proposed to act as a negative feedback 'adipostatic signal' to brain centres controlling energy homeostasis, limiting obesity in times of nutritional abundance. Starvation is also a threat to homeostasis that triggers adaptive responses, but whether leptin plays a role in the physiology of starvation is unknown. Leptin concentration falls during starvation and totally leptin-deficient ob/ob mice have neuroendocrine abnormalities similar to those of starvation, suggesting that this may be the case. Here we show that preventing the starvation-induced fall in leptin with exogenous leptin substantially blunts the changes in gonadal, adrenal and thyroid axes in male mice, and prevents the starvation-induced delay in ovulation in female mice. In contrast, leptin repletion during this period of starvation has little or no effect on body weight, blood glucose or ketones. We propose that regulation of the neuroendocrine system during starvation could be the main physiological role of leptin.

Serum steroid hormone levels, sex hormone-binding globulin, and body mass index in the etiology of postmenopausal breast cancer

Serum concentrations of estrone, androstenedione, testosterone, and sex hormone-binding globulin (SHBG) were measured postoperatively in 122 postmenopausal women with incident breast cancer and 122 age-matched population controls. After mutual adjustment, through conditional logistic regression, between the hormonal variables and body mass index (BMI), the odds ratios for increasing control-defined quartiles of estrone and androstenedione, respectively, were 1.00, 1.44, 1.76, 1.94 and 1.00, 0.83, 0.97, 2.43; there was no association of testosterone with breast cancer risk. Moreover, the odds ratios for increasing quartiles of SHBG and BMI were 1.00, 0.72, 0.28, 0.25 and 1.00, 0.39, 0.28, 0.19, respectively. This study reveals sharp contrasts in breast cancer risk between women with high estrone and low BMI and SHBG, vs women with low estrone and high BMI and SHBG.

Genetic variability in the TNF-alpha promoter is not associated with type II diabetes mellitus (NIDDM)

Recent evidence suggests that expression of tumor necrosis factor-alpha (TNF-alpha) by adipocytes is a molecular mediator of insulin resistance in obesity. We have therefore tested the hypothesis that variations within the regulatory region of the TNF-alpha gene, which might cause increased adipocyte or generalized TNF-alpha synthesis, are associated with NIDDM, a state in which insulin resistance is routinely observed. Neither the previously known variants within the TNF-alpha promoter at position -308 and -238, nor two newly identified polymorphisms at position -376 and -163, were found at a significantly higher frequency in Caucasian NIDDM patients compared to non-diabetic controls. No genetic variants were found in Pima Indians. These data make it unlikely that mutations within regulatory elements of the TNF-alpha gene are associated with an increase in the prevalence of NIDDM.