EZHL-80SK MilliporeHuman Leptin "Dual Range" ELISA

Fasting leptin and ghrelin levels were measured in 36 insulin-sensitive (IS) and 28 insulin-resistant (IR) men who consumed a legume-enriched low-glycemic index (LG) diet or healthy American (HA) diet in a randomly ordered cross-over feeding study consisting of two 4-week periods. Weight remained stable over the entire study. Fasting plasma leptin was significantly reduced from pre-study levels by both the LG (18.8%, P < 0.001) and HA (16.1%, P < 0.001) diets, whereas fasting ghrelin did not change. By subgroup analysis according to prestudy insulin status, leptin was reduced in IR subjects after both the LG (17.1%, P < 0.01) and the HA (33.3%, P < 0.001) diets, whereas IS subjects responded only after the LG diet (23.1%, P < 0.01). Thus, a legume-rich LG index diet may be a beneficial strategy for reducing circulating leptin concentrations, even under conditions of weight maintenance.

This study was designed to determine whether sprint exercise activates signaling cascades linked to leptin actions in human skeletal muscle and how this pattern of activation may be interfered by glucose ingestion. Muscle biopsies were obtained in 15 young healthy men in response to a 30-s sprint exercise (Wingate test) randomly distributed into two groups: the fasting (n = 7, C) and the glucose group (n = 8, G), who ingested 75 g of glucose 1 h before the Wingate test. Exercise elicited different patterns of JAK2, STAT3, STAT5, ERK1/2, p38 MAPK phosphorylation, and SOCS3 protein expression during the recovery period after glucose ingestion. Thirty minutes after the control sprint, STAT3 and ERK1/2 phosphorylation levels were augmented (both, P < 0.05). SOCS3 protein expression was increased 120 min after the control sprint but PTP1B protein expression was unaffected. Thirty and 120 min after the control sprint, STAT5 phosphorylation was augmented (P < 0.05). Glucose abolished the 30 min STAT3 and ERK1/2 phosphorylation and the 120 min SOCS3 protein expression increase while retarding the STAT5 phosphorylation response to sprint. Activation of these signaling cascades occurred despite a reduction of circulating leptin concentration after the sprint. Basal JAK2 and p38 MAPK phosphorylation levels were reduced and increased (both P < 0.05), respectively, by glucose ingestion prior to exercise. During recovery, JAK2 phosphorylation was unchanged and p38 MAPK phosphorylation was transiently reduced when the exercise was preceded by glucose ingestion. In conclusion, sprint exercise performed under fasting conditions is a leptin signaling mimetic in human skeletal muscle.

Animals' attitudes to risk are profoundly influenced by metabolic state (hunger and baseline energy stores). Specifically, animals often express a preference for risky (more variable) food sources when below a metabolic reference point (hungry), and safe (less variable) food sources when sated. Circulating hormones report the status of energy reserves and acute nutrient intake to widespread targets in the central nervous system that regulate feeding behaviour, including brain regions strongly implicated in risk and reward based decision-making in humans. Despite this, physiological influences per se have not been considered previously to influence economic decisions in humans. We hypothesised that baseline metabolic reserves and alterations in metabolic state would systematically modulate decision-making and financial risk-taking in humans.

Leptin is an adipocyte-derived protein and plays an important role in the control of body weight by acting as a neurohormone regulating energy balance and food intake in the hypothalamus. The high serum leptin levels and the overexpression of leptin receptors have been documented in breast cancer patients, but the levels never checked preoperatively. In the present study, the relationship between preoperative serum leptin levels of the breast cancer patients and the healthy controls were evaluated. The serum leptin levels in 30 breast cancer patients were compared to 30 healthy female volunteers. In addition, the association of serum leptin levels and the various well-known risk factors were studied. Serum leptin levels of patients with breast cancer (28.55 + 19.7 ng/ml) were tended to be higher than those of controls (26.43 + 19.4 ng/ml), but it did not reach statistical difference (P = 0.712). There was significant correlation between the expression of ER, PR, and serum leptin levels (P = 0.018 and 0.037, respectively), but not with the HER-2/neu receptor expression (P = 0.067). Also association was not found between the tumor size, lymph node involvement, and the levels of serum leptin (P = 0.235, 0.34, and 0.86, respectively). The serum leptin level was also found to be similar in premenopausal (24.85 +/- 18.14 ng/ml) and postmenopausal (30.49 +/- 17.19 ng/ml) patients (P = 0.235). The preoperative serum leptin levels in breast cancer patients were similar to healthy controls. In subset analysis, the significant correlation between the leptin level and hormonal status was noted, but association with HER-2/neu was not detected. These findings should be confirmed with larger studies.

To determine if there is a gender dimorphism in the expression of leptin receptors (OB-R170, OB-R128 and OB-R98) and the protein suppressor of cytokine signaling 3 (SOCS3) in human skeletal muscle, the protein expression of OB-R, perilipin A, SOCS3 and alpha-tubulin was assessed by Western blot in muscle biopsies obtained from the m. vastus lateralis in thirty-four men (age = 27.1+/-6.8 yr) and thirty-three women (age = 26.7+/-6.7 yr). Basal serum insulin concentration and HOMA were similar in both genders. Serum leptin concentration was 3.4 times higher in women compared to men (P<0.05) and this difference remained significant after accounting for the differences in percentage of body fat or soluble leptin receptor. OB-R protein was 41% (OB-R170, P<0.05) and 163% (OB-R128, P<0.05) greater in women than men. There was no relationship between OB-R expression and the serum concentrations of leptin or 17beta-estradiol. In men, muscle OB-R128 protein was inversely related to serum free testosterone. In women, OB-R98 and OB-R128 were inversely related to total serum testosterone concentration, and OB-R128 to serum free testosterone concentration. SOCS3 protein expression was similar in men and women and was not related to OB-R. In women, there was an inverse relationship between the logarithm of free testosterone and SCOS3 protein content in skeletal muscle (r = -0.46, P<0.05). In summary, there is a gender dimorphism in skeletal muscle leptin receptors expression, which can be partly explained by the influence of testosterone. SOCS3 expression in skeletal muscle is not up-regulated in women, despite very high serum leptin concentrations compared to men. The circulating form of the leptin receptor can not be used as a surrogate measure of the amount of leptin receptors expressed in skeletal muscles.

Background. Burns are a unique injury which not only is devastating for the patients but also puts a great burden on society by consuming enormous health care resources. Despite improvements in burn wound care and treatment, understanding the role of pro-inflammatory and anti-inflammatory cytokines as well as the mechanisms responsible for the healing process remains to be clarified. Although leptin is regarded as a circulating hormone, it can exert a direct effect on T cells and monocytes, causing the release of cytokines. It may induce angiogenesis or influence angiogenic factors. The aim of the present work is to determine serum levels of leptin, tumour necrosis factor a (TNFa), interleukin-6 (IL-6), basic fibroblast growth factor (bFGF), procalcitonin (PCT), and C-reactive protein (CRP) in a group of children with thermal burns and to determine the changes in these parameters in relation to the duration of hospital stay, the presence of infection, and the total body surface area (TBSA) burned. Patients and methods. The study included 42 children with burns (22 males and 20 females; age range, 2 months to 7 years). The study also included 26 age-matched controls. Besides full clinical assessment, including assessment of TBSA burned and the presence or absence of sepsis, all the patients and controls had the following investigations performed: complete blood count, CRP, IL-6, TNFa, PCT, serum leptin, bFGF, and transforming growth factor a (TGFa). Results. The fatality rate in this study was 28.6%. Burn cases as a whole showed significantly higher values of white blood cells (WBC), CRP, PCT, TNFa, IL-6, leptin, bFGF, and TGFa than controls. Cases with sepsis showed significantly higher values of WBC, CRP, PCT, TNFa, and IL-6 than cases without sepsis. They showed significantly lower values of TGFa than cases without sepsis. Patients with larger TBSA (>30%) showed significantly higher levels of WBC, CRP, PCT, TNFa, IL-6, and leptin than cases with smaller TBSA. They showed significantly lower levels of bFGF and TGFa than patients with smaller TBSA. Non-survivors showed significantly higher levels of WBC, CRP, PCT, TNFa, and IL-6 than survivors. They showed significantly lower levels of leptin, bFGF, and TGFa than survivors. Correlation studies showed a significant positive correlation between TBSA and each of IL-6, TNFa, and leptin. Conclusions. Cytokines and leptin increased in severely burned patients, cases associated with sepsis, and in fatal cases, while bFGF and TGFa levels were lower in severe cases. This may point to impaired healing in such cases and to their poorer prognosis. Recommendations. It is highly recommended to monitor immunological parameters such as PCT and/or IL-6 for early detection of infectious complications following thermal injury. Leptin can be regarded as a novel treatment modality to diminish burn-induced inflammation, reduce post-burn immune dysfunction, and enhance burn healing.