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Biomedical subjects

C S Mantzoros

Publications and source records attributed to C S Mantzoros.

At least 19 recordsLinked to original sources
PubMed2006

Relationship between a wide range of alcohol consumptions, components of the insulin-like growth factor system and adiponectin.

OBJECTIVE: To explore the relation between a wide range of alcohol consumptions and levels of the components of insulin-like growth factor system (IGFs) and adiponectin in humans. DESIGN: A cross-sectional study using controls from a case-control study on ovarian and endometrial cancer. SETTINGS: The study included women hospitalized between 1999 and 2002 in Pordenone, Italy. SUBJECTS: One hundred and eight cancer-free (controls) with a median age of 61 years (range 29-79 years), admitted for acute conditions unrelated to gynecologic, hormonal or metabolic disorders or diseases leading to dietary modifications. INTERVENTIONS: Levels of IGF-I (total and free), total IGF-II, IGF-binding protein 1 (IGFBP-1), IGFBP-3 and adiponectin were individually measured, and their distributions across strata of alcohol consumption were tested by the Kruskal-Wallis statistic. RESULTS: Median concentrations of total IGF-I were higher (P<0.01) in women reporting low (151 ng/ml) or no alcohol consumption (134 ng/ml) compared to drinkers of 12-23 g/day (103 ng/ml) or >or=24 g/day (118 ng/ml). Median concentrations were higher (P=0.05) for IGFBP-3 in non-drinkers (2333 ng/ml) and in light drinkers (2647 ng/ml) compared to drinkers of >or=24 g/day (2090 ng/ml). No statistically significant difference emerged for other IGFs across levels of alcohol intakes. Adiponectin was slightly lower for non-drinkers, compared to all drinkers categories. CONCLUSIONS: Our study suggests that alcohol consumption is related to circulating levels of components of the IGF system and adiponectin. These results may have a potential impact on the prevention of several chronic diseases. SPONSORSHIP: Italian Association for Research on Cancer, Milan, Italy, and Italian League against Tumours, Milan, Italy.

Adiponectin↗
PubMed2006

Adiponectin and cancer: a systematic review.

Recent studies have demonstrated that obesity is a significant risk factor for the development of several malignancies, but the mechanisms underlying this relationship remain to be fully elucidated. Adiponectin, an adipocyte secreted endogenous insulin sensitizer, appears to play an important role not only in glucose and lipid metabolism but also in the development and progression of several obesity-related malignancies. In this review, we present recent findings on the association of adiponectin with several malignancies as well as recent data on underlying molecular mechanisms that provide novel insights into the association between obesity and cancer risk. We also identify important research questions that remain unanswered.

Adiponectin↗
PubMed2006

Adiponectin in relation to childhood myeloblastic leukaemia.

Adiponectin, an adipocyte-specific secretory protein known to induce apoptosis, has been reported to be inversely related to breast and endometrial cancers and recently found to inhibit proliferation of myeloid but not lymphoid cell lines. We hypothesised that adiponectin may be inversely associated with acute myeloblastic leukaemia (AML), but not with acute lymphoblastic leukaemia of B (ALL-B) or T (ALL-T) cell origin in children. Blood samples and clinical information were collected over the period 1996-2000 from 201 children (0-14 years old) with leukaemia (22 AML, 161 ALL-B and 18 ALL-T cases) through a national network of childhood Hematology-Oncology units in Greece and from 201 controls hospitalised for minor pediatric ailments. Serum adiponectin levels were measured under code, at the Beth Israel Deaconess Medical Center, Boston, MA, USA using a radioimmunoassay procedure. Each of the three leukaemia groups was compared with the control group through multiple logistic regression. Odds ratios (OR) and 95% confidence intervals (95% CI) for an increase of adiponectin equal to 1 s.d. among controls were estimated controlling for gender, age, as well as for height and weight, expressed in age-gender-specific centiles of Greek growth curves. Adiponectin was inversely associated with AML (OR=0.56; 95% CI, 0.34-0.94), whereas it was not significantly associated with either ALL-B (OR=0.88; 95% CI, 0.71-1.10) or ALL-T (OR=1.08; 95% CI, 0.67-1.72). Biological plausibility and empirical evidence point to the importance of this hormone in the pathogenesis of childhood AML.

Adiponectin↗
PubMed2005

Peptide YY levels are decreased by fasting and elevated following caloric intake but are not regulated by leptin.

AIMS/HYPOTHESIS: Peptide YY (PYY) is a gut-derived hormone that has been shown to reduce short-term food intake in animals and humans. It has been proposed that deficiency of PYY contributes to obesity in humans. However, the physiology of PYY regulation by factors such as caloric restriction, or by other molecules important in energy homeostasis, e.g. leptin, remains to be fully elucidated. MATERIALS AND METHODS: We evaluated the effect on PYY levels of: (1) caloric ingestion (a mixed meal) in five healthy normal-weight subjects; (2) fasting for 2 or 3 days in eight lean men and seven lean women respectively; and (3) recombinant human leptin administration at physiological replacement and pharmacological doses. RESULTS: PYY levels increased 50% after a mixed meal (p=0.01), and short-term complete fasting for 2 or 3 days decreased leptin and PYY levels to 20-30% and 40-60% of baseline, respectively (both p<0.05). However, recombinant human leptin administration at physiological doses to restore the fasting-induced decrease of leptin levels and at pharmacological doses over the short term had no effect on PYY levels. CONCLUSIONS/INTERPRETATION: PYY increases after meal ingestion and decreases after fasting in a manner consistent with a meal-related signal of energy homeostasis. Importantly, circulating levels of this gut-secreted molecule are independent of regulation by leptin over the short term. These findings contribute towards our understanding of the homeostatic systems that regulate appetite in humans, including the possible redundancy of gastrointestinally secreted and adipocyte-secreted signals. This may be of importance for the future development of medications to treat obesity.

Eating↗
PubMed2004

The Val81 missense mutation of the melanocortin 3 receptor gene, but not the 1908c/T nucleotide polymorphism in lamin A/C gene, is associated with hyperleptinemia and hyperinsulinemia in obese Greek caucasians.

Obesity-related phenotypes have been linked to human chromosomes 1q21 and 20q13, regions where the lamin A/C gene (LMNA) and the melanocortin 3 receptor gene (MC3R) map, respectively. Recently, a common single nucleotide polymorphism (SNP) in LMNA (1908C/T) was associated with plasma leptin and obesity indices in aboriginal Canadians, but these associations have not yet been explored in other populations. In contrast, no significant associations of MC3R variants with obesity have been detected, although a significant association with hyperinsulinemia has been reported in Caucasian populations. We investigated the associations between the LMNA 1908C/T variant and the 241G/A variant of the MC3R gene (Val81Ile missense mutation) and body composition, as well as plasma leptin and insulin levels, in two samples of unrelated healthy Greek subjects. A group of 112 young nonobese subjects, and a group of 116 adult women with a body mass index (BMI) ranging from 23.2 to 47.7 kg/m2 were studied cross-sectionally. We found no significant association of the LMNA 1908C/T and a borderline significant association of MC3R 241G/A SNPs with body composition variables, in the entire study sample. However, unlike the LMNA 1908C/T genetic variation, the MC3R 241G/A genetic variation was significantly associated with hyperleptinemia and huperinsulinemia in obese subjects, and there was evidence of interaction between this polymorphism and fat mass or BMI in predicting hyperinsulinemia. Our results suggest that the LMNA 1908C-->T substitution and the Val81Ile mutation of the MC3R gene are unlikely to be major predictors of body composition in Greek Caucasians, but the latter genetic variation may predispose obese subjects to develop insulin and leptin resistance. Future studies are needed to confirm these data and assess whether individuals carrying this mutation are more resistant to weight-reducing and insulin-sensitizing treatments.

Adult↗
PubMed2003

Sleep loss reduces diurnal rhythm amplitude of leptin in healthy men.

The aim of the current study was to investigate the effects of sleep loss on the diurnal rhythm of circulating leptin levels. An indwelling forearm catheter was used to sample blood at 90-min intervals for a total of 120 h, which included 88 h of sustained sleeplessness, in 10 healthy men. The diurnal amplitude of leptin was reduced during total sleep deprivation and returned toward normal during the period of recovery sleep. This finding provides evidence that sleep influences the nocturnal leptin profile, and may have implications for the understanding of the role of sleep in metabolic regulation and the aetiologies of obesity and the night eating syndrome.

Adult↗
PubMed2001

The role of leptin and hypothalamic neuropeptides in energy homeostasis: update on leptin in obesity.

Leptin is an adipocyte-secreted hormone the serum levels of which reflect the amount of energy stored in adipose tissue as well as short-term energy imbalance. Serum levels of many cytokines and hormones also influence circulating leptin levels. Leptin binding to specific receptors in the hypothalamus results in altered expression of orexigenic and anorexigenic neuropeptides that regulate neuroendocrine function and energy homeostasis, and recent experimental evidence suggests that leptin plays an important role in the pathogenesis of obesity and eating disorders. Research that followed the discovery of leptin is significantly broadening our understanding of the mechanisms underlying energy homeostasis, the elucidation of which is expected to result soon in the development of new therapeutic approaches for obesity and eating disorders.

Animals↗
PubMed2001

Serum leptin levels are higher but are not independently associated with severity or mortality in the multiple organ dysfunction/systemic inflammatory response syndrome: a matched case control and a longitudinal study.

OBJECTIVE: Hypercatabolism and immune dysfunction are closely associated with the development of systemic inflammatory response--multiple organ dysfunction (SIRS/MODS) in critical illness. It remains unclear however, whether leptin, an adipocyte-derived hormone whose levels are influenced by several cytokines and which regulates immune function, food-intake and energy expenditure is independently related to the development of and/or severity and mortality from SIRS/MODS. DESIGN AND PATIENTS: To assess the role of leptin in SIRS/MODS we performed a matched case control and a longitudinal study (14 days) in 35 critically ill patients with SIRS/MODS and 35 matched controls. RESULTS: Baseline leptin levels were positively associated with body mass index (BMI) and TNF-alpha (P < 0.01) in patients and with IGF-1 and IL-6 levels (P < 0.05) in controls. Furthermore, leptin levels exhibited a progressive increase from the first to the last day of the study and although baseline levels were not different, peak leptin levels as well as leptin levels on the last day of the study were significantly higher in cases than in controls (P < 0.05). TNF-alpha levels, IL-6 and cortisol levels were also higher, whereas IGF-1 levels were lower in cases (P < 0.05). To assess whether leptin levels are independently associated with SIRS/MODS we performed multivariate logistic regression analysis which revealed that leptin up-regulation in cases is mediated by elevated TNF-alpha and cortisol levels. Finally, there was no independent association between leptin and survival in this group of critically ill patients. CONCLUSION: We conclude that cytokines and cortisol upregulate leptin levels, which may contribute to the development of the hypercatabolism, wasting and immune dysfunction but leptin levels are not independently associated with severity or mortality of patients with systemic inflammatory response-multiple organ dysfunction.

Adult↗
PubMed2001

Fluconazole vs. amphotericin B for the management of candidaemia in adults: a meta-analysis.

The incidence of bloodstream infections caused by Candida species is rising. Few published studies have compared the efficacy of fluconazole with that of amphotericin B. We performed a meta-analysis of the prospective studies that compared fluconazole and amphotericin B for the treatment of candidaemia in adults. Data on total mortality, candidaemia-attributable mortality, efficacy, microbiological failure, and toxicity were extracted from eligible studies. All studies appeared homogeneous with respect to the outcome measures. Most patients were at relatively low risk for death as evidenced by the low average physiologic score and the lack of intense immunosuppression. The odds ratios (OR) of treatment with amphotericin B versus fluconazole and 95% confidence intervals (CI) were as follows: total mortality (OR, 1.06; CI, 0.89-1.25), candidaemia-attributable mortality (OR, 1.0; CI, 0.70-1.45), clinical response (OR, 1.14; CI, 0.93-1.39) and microbiological failure according to all Candida species (OR, 0.99; CI, 0.78-1.26). A trend favouring amphotericin B was seen in mycological eradication of non-albicans Candida species (OR, 0.70; CI, 0.47-1.06). Finally, amphotericin B was more toxic than fluconazole (OR, 2.94; CI, 2.14-4.4). In conclusion, fluconazole is as efficacious and less toxic than amphotericin B in stable, not severely immunosuppressed candidaemic patients at low risk for death. However, fluconazole may be less effective than amphotericin B in candidaemias caused by some non-albicans Candida species.

Adult↗
PubMed2001

Cord blood leptin and insulin-like growth factor levels are independent predictors of fetal growth.

The insulin-like growth factor (IGF) system is the dominant endocrine regulator of fetal growth, whereas insulin has a permissive role. Although a role for leptin in fetal growth has been suggested recently, the mechanism by which leptin may be related to fetal growth is not known; but leptin may interact with the IGF system in utero as it does in the extrauterine life. In the context of a hospital-based case control study, we collected anthropometric and demographic data and measured serum leptin, IGF-I, IGF-II, insulin, cortisol, and IGF binding protein 3 concentrations in 142 cord blood samples from full-term deliveries. Cord leptin, IGF-I, and insulin levels correlated positively with birth weight (r = 0.46, r = 0.41, and r = 0.21, respectively, P < 0.01) by univariate analysis and were significantly higher in large-for-gestational-age (LGA) infants, compared with appropriate-for-gestational-age (AGA) infants. Cord leptin concentrations correlated with insulin levels (r = 0.36, P < 0.01) but not with IGF-I levels (r = 0.20). Multiple linear and logistic regression analysis demonstrated an independent positive relationship of both leptin and IGF-I with birth weight and AGA/LGA status. The positive association of leptin levels with birth weight and AGA/LGA status cannot be attributed to IGF-I. This suggests the existence of alternative mechanisms underlying leptin's associations with fetal growth that should be further explored.

Analysis of Variance↗
PubMed2001

Synchronicity of frequently sampled thyrotropin (TSH) and leptin concentrations in healthy adults and leptin-deficient subjects: evidence for possible partial TSH regulation by leptin in humans.

Leptin signals the status of energy reserves to the brain. Leptin stimulates biosynthesis of TRH in vitro and influences the activity of the hypothalamic-pituitary-thyroid axis in vivo in rodents. Because blood levels of both leptin and TSH display diurnal variation with a distinct nocturnal rise, we sought to determine whether a relationship exists between fluctuations in circulating leptin and TSH. We measured serum leptin and TSH levels every 7 min for 24 h in five healthy men and found that both leptin and TSH levels are highly organized and pulsatile. A similar pattern of leptin and TSH rhythms was observed, with TSH and leptin levels reaching a nadir in late morning and a peak in the early morning hours. Importantly, cosinor analysis on the absolute leptin and TSH levels revealed a statistically significant fit for a 24-h period and the two hormones showed similar probabilities of rhythm and superimposable peak values. Furthermore, this study shows a strong positive Pearson correlation between the 24-h patterns of variability of leptin and TSH in healthy subjects. Finally, the ultradian fluctuations in leptin levels showed pattern synchrony with those of TSH as determined by cross-correlation analysis, by cross-approximate enthropy and Bayessian analysis applied independently. To further explore whether these associations could reflect an underlying regulation of TSH secretion by leptin, we also studied frequently sampled leptin and TSH levels in four brothers, members of a family with leptin deficiency (one normal homozygote, two heterozygotes, and one leptin-deficient homozygote). Leptin levels of the homozygous leptin-deficient subject are detectable but bioinactive, and the rhythm of his TSH is disorganized. 24-h pattern of leptin and TSH variability in the heterozygous subjects, although significantly correlated, showed a weaker correlation compared with the strong correlation in the normal subjects. These data are consistent with the possibility that leptin may regulate TSH pulsatility and circadian rhythmicity, but interventional studies are needed to definitively prove whether leptin regulates the minute-to-minute oscillations and ultradian rhythm of TSH levels.

Adult↗
PubMed2001

The Q223R polymorphism of the leptin receptor gene is significantly associated with obesity and predicts a small percentage of body weight and body composition variability.

Genetic variation at the leptin receptor gene locus may play an important role in the pathophysiology of human obesity, a leptin-resistant state. Previous studies exploring potential associations between leptin receptor gene polymorphisms and obesity have reported conflicting results. The aim of this study was to evaluate a genetically homogeneous population for associations between body composition variables and three common leptin receptor gene polymorphisms (K109R, Q223R, and K656N) that have potential functional significance as well as to assess the contributions of these polymorphisms to the variability of obesity. One hundred and eighteen consecutively enrolled subjects (62 women: mean age, 17.5 +/- 1.6 yr; body mass index range, 16.2-30.1; 56 men: mean age, 17.8 +/- 1.8 yr; body mass index range, 15.4-35.9) were genotyped for the three polymorphisms, and their body mass index, sum of 4 skinfolds, fat-free mass, percent fat mass, serum leptin levels, caloric intake, fat intake, and exercise patterns were determined. Allele frequencies were estimated by the gene-counting method, and genotype distributions between 89 normal weight (body mass index, < or =25 kg/m(2)) and 29 overweight-obese (body mass index, >25 kg/m(2)) subjects were compared using chi(2) test (using codominant, dominant, and recessive models). Analysis of covariance was also performed to evaluate associations between the polymorphisms and body composition variables after controlling for potential confounders. For the Q223R polymorphism, there was a higher prevalence of the R223 allele in the homozygous form among overweight-obese subjects vs. normal weight subjects (20.7% vs. 4.5%; P = 0.01). Furthermore, simple and multiple regression analyses revealed that the R223 allele in the homozygous form is a significant predictor of both body mass index (P = 0.015) and percent fat mass (P = 0.02) even after adjusting for age and gender and explains 4.5% of the variance in percent fat mass and 5% of the variance in body mass index. There was no significant difference in allele frequencies or genotype distributions for the K109R or K656N polymorphisms. These findings support the hypothesis that the Q223R polymorphism (but not the K109R or K656N polymorphism) of the leptin receptor gene is associated with obesity and predicts a small percentage of body weight and body composition variability in a genetically homogeneous population.

Adolescent↗
PubMed2000

Can measurements of IGF-1 and IGFBP-3 improve the sensitivity of prostate-cancer screening?

Further well designed studies are urgently needed to clarify if use of prostate-specific antigen (PSA) as a diagnostic test for prostate cancer can be improved by incorporating measurements of serum insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding-protein 3 (IGFBP-3), and if these measurements might also identify men at higher risk.

Humans↗
PubMed2000

Predictive value of serum and follicular fluid leptin concentrations during assisted reproductive cycles in normal women and in women with the polycystic ovarian syndrome.

Leptin is an adipocyte-derived hormone which plays a central role in the regulation of body weight and energy homeostasis and in signalling to the brain that adequate energy stores are available for reproduction. Although leptin may affect reproduction by regulating the hypothalamic-pituitary-gonadal axis, recent in-vitro observations indicate that leptin may also have direct intra-ovarian actions. Leptin concentrations were measured in women who succeeded in becoming pregnant within three cycles of in-vitro fertilization (IVF) or gamete intra-fallopian transfer (n = 53), in women who failed to become pregnant within three cycles (n = 50), and in women with polycystic ovarian syndrome (PCOS) (n = 22). It was found that lower follicular fluid leptin concentrations were a marker of assisted reproduction treatment success in normal women. Women with PCOS had higher leptin concentrations than women without such a diagnosis, but this was due to their higher body mass index (BMI). After adjustment for age and BMI, women with PCOS who became pregnant tended to have lower mean follicular fluid leptin concentrations than women with PCOS who did not succeed at becoming pregnant. Further studies exploiting the strengths of the IVF model are needed to assess whether the prognostic role for follicular fluid leptin in human reproduction is independent of other factors, and to elucidate the underlying mechanisms.

Adult↗
PubMed2000

Role of leptin in reproduction.

Leptin is a 16-kDa adipocyte-secreted protein the serum levels of which reflect mainly the amount of energy stores but are also influenced by short-term energy imbalance as well as several cytokines and hormones. Leptin, by binding to specific receptors, alters the expression of several hypothalamic neuropeptides that regulate neuroendocrine function as well as energy intake and expenditure. More specifically, accumulating evidence suggests that this hormone may serve to signal to the brain information on the critical amount of fat stores that are necessary for LHRH secretion and activation of the hypothalamic-pituitary-gonadal axis. Rising leptin levels have been associated with initiation of puberty in animals and humans and normal leptin levels are needed for maintenance of menstrual cycles and normal reproductive function. Moreover, circadian and ultradian variations of leptin levels are associated with minute to minute variations of LH and estradiol in normal women. Falling leptin levels in response to starvation result in decreased estradiol levels and amenorrhea in subjects with anorexia nervosa or strenuously exercising athletes. In addition, leptin has a potentially important role during pregnancy and in the physiology of the neonate. Finally, recent evidence suggests that leptin may influence ovarian steroidogenesis directly, but the exact role of intraovarian leptin action in the physiology and pathophysiology of the human reproductive system needs to be further elucidated.

Feeding and Eating Disorders↗
PubMed2000

Differential expression of hypothalamic neuropeptides in the early phase of diet-induced obesity in mice.

Exposure to high-fat diets for prolonged periods results in positive energy balance and obesity, but little is known about the initial physiological and neuroendocrine response of obesity-susceptible strains to high-fat feeding. To assess responses of C57BL/6J mice to high- and low-fat diets, we quantitated the hypothalamic expression of neuropeptides implicated in weight regulation and neuroendocrine function over a 2-wk period. Exposure to high-fat diet increased food consumption over a 2-day period during which leptin levels were increased when assessed by a frequent sampling protocol [area under the curve (AUC): 134.6 +/- 10.3 vs. 100 +/- 12.3, P = 0.03 during first day and 126.5 +/- 8.2 vs. 100 +/- 5.2, P = 0.02 during second day]. During this period, hypothalamic expression of neuropeptide Y (NPY) and agouti-related protein (AgRP) decreased by approximately 30 and 50%, respectively (P < 0.001). After 1 wk, both caloric intake and hypothalamic expression of NPY and AgRP returned toward baseline. After 2 wk, cumulative caloric intake was again higher in the high-fat group, and now proopiomelanocortin (POMC) was elevated by 76% (P = 0.01). This study demonstrates that high-fat feeding induces hyperphagia, hyperleptinemia, and transient suppression of orexigenic neuropeptides during the first 2 days of diet. The subsequent induction of POMC may be a second defense against obesity. Attempts to understand the hypothalamic response to high-fat feeding must examine the changes as they develop over time.

Agouti-Related Protein↗
PubMed2000

Hormonal predictors of prostate cancer: a meta-analysis.

PURPOSE: Although there is strong circumstantial evidence that androgens are implicated in the etiology of prostate cancer, epidemiologic investigations have failed to demonstrate consistently that one or more steroid hormones are implicated. In contrast, recent epidemiologic studies unequivocally link serum insulin-like growth factor 1 (IGF-1) levels with risk for prostate cancer. METHODS: We have performed the first meta-analysis of all previously published studies on hormonal predictors of risk for prostate cancer. RESULTS: A meta-analysis restricted to studies that performed mutual adjustment for all measured serum hormones, age, and body mass index indicated that men whose total testosterone is in the highest quartile are 2.34 times more likely to develop prostate cancer (95% confidence interval, 1.30 to 4.20). In contrast, levels of dihydrotestosterone and estradiol do not seem to play a role of equal importance. The only study that provides multivariably adjusted sex hormone-binding globulin data indicates that this binding protein is inversely related to prostate cancer risk (odds ratio, 0.46; 95% confidence interval, 0.24 to 0.89). Finally, all three studies that examined the role of serum IGF-1 have consistently demonstrated a positive and significant association with prostate cancer risk that is similar in magnitude to that of testosterone. CONCLUSION: Men with either serum testosterone or IGF-1 levels in upper quartile of the population distribution have an approximately two-fold higher risk for developing prostate cancer.

Age Factors↗