Galanin peptide family as a modulating target for contribution to metabolic syndrome.

Metabolic syndrome (MetS) is defined as abdominal central obesity, atherogenic dyslipidemia, insulin resistance, glucose intolerance and hypertension. The rapid increasing prevalence of MetS and the consequent diseases, such as type 2 diabetes mellitus and cardiovascular disorder, are becoming a global epidemic health problem. Despite considerable research into the etiology of this complex disease, the precise mechanism underlying MetS and the association of this complex disease with the development of type 2 diabetes mellitus and increased cardiovascular disease remains elusive. Therefore, researchers continue to actively search for new MetS treatments. Recent animal studies have indicated that the galanin peptide family of peptides may increase food intake, glucose intolerance, fat preference and the risk for obesity and dyslipidemia while decreasing insulin resistance and blood pressure, which diminishes the probability of type 2 diabetes mellitus and hypertension. To date, however, few papers have summarized the role of the galanin peptide family in modulating MetS. Through a summary of available papers and our recent studies, this study reviews the updated evidences of the effect that the galanin peptide family has on the clustering of MetS components, including obesity, dyslipidemia, insulin resistance and hypertension. This line of research will further deepen our understanding of the relationship between the galanin peptide family and the mechanisms underlying MetS, which will help develop new therapeutic strategies for this complex disease.

Exercise-induced galanin release facilitated GLUT4 translocation in adipocytes of type 2 diabetic rats.

Although galanin has been shown to increase insulin sensitivity in skeletal muscle of rats, there is no literature available about the effect of galanin on Glucose Transporter 4 (GLUT4) translocation from intracellular membrane pools to plasma membranes in adipocytes of type 2 diabetic rats. In the present study M35, a galanin antagonist was used to elucidate whether exercise-induced galanin release increased GLUT4 translocation in adipocytes of streptozotocin-induced diabetic rats. The present findings showed that plasma galanin levels after swimming training in all four trained groups were higher compared with each sedentary control. M35 treatment had an inhibitory effect on glucose infusion rates in the euglycemic-hyperinsulinemic clamp test and GLUT4 mRNA expression levels in adipocytes. Moreover, M35 treatment reduced GLUT4 concentration in both plasma membranes and total cell membranes. The ratios of GLUT4 contents in plasma membranes to total cell membranes in four drug groups were lower compared with each control. These data demonstrate a beneficial role of endogenous galanin to transfer GLUT4 from internal stores to plasma membranes in adipocytes of type 2 diabetic rats. Galanin plays a significant role in regulation of glucose metabolic homeostasis and is an important hormone relative to diabetes.

Central nervous system regulation of food intake and energy expenditure: role of galanin-mediated feeding behavior.

Galanin is a neuropeptide widely expressed in the brain. It is implicated in energy expenditure, feeding, and the regulation of body weight. Numerous studies have revealed that galanin regulates food intake via galanin receptors, 5-HT(1A) receptor and adrenergic α-2 receptor. In this review, we summarize recent findings that reveal the essential role of galanin in increasing food intake as well as body weight and that identify the individual galanin receptor subtypes involved in the brain's modulation of food intake and energy expenditure, to provide a theoretical basis for further studies of different aspects of galanin action.

Galanin antagonist increases insulin resistance by reducing glucose transporter 4 effect in adipocytes of rats.

Seeing that galanin increases animal body weight on the conditions of inhibiting insulin secretion and animals with metabolic disorder of galanin easily suffer from diabetes, we postulate that endogenous galanin is necessary to reduce insulin resistance in adipocytes. To test this hypothesis, we compared four groups of rats to examine whether an increase in galanin secretion stimulated by swimming may reduce insulin resistance. The rats from sedentary and trained drug groups were injected by M35, a galanin antagonist. The rats from trained control and trained drug groups swam after each injection for four weeks. We found that exercise significantly elevated plasma galanin contents and glucose transporter 4 (GLUT4) mRNA levels in adipocytes. Meanwhile, M35 treatment reduced GLUT4 and GLUT4 mRNA levels, and glucose infusing rates in euglycemic-hyperinsulinemic clamp tests. The ratios of GLUT4 concentrations at plasma membranes to total cell membranes in both drug groups were lower compared with each control group, respectively. These observations suggest that endogenous galanin reduces insulin resistance by increasing GLUT4 contents and promoting GLUT4 transportation from intracellular membranes to plasma membranes in adipocytes. Galanin is an important hormone to reduce insulin resistance in rats.

Beneficial effect of galanin on insulin sensitivity in muscle of type 2 diabetic rats.

The aim of this study was to determine whether enhanced galanin (GAL) release induced by exercise would elevate insulin sensitivity and glucose transporter 4 (GLUT4) concentration in the plasma membranes of skeletal muscle in type 2 diabetic rats. We used M35, a GAL antagonist to antagonize the GAL function and swimming training for four weeks to increase GAL release of rats. The blood samples were analyzed for GAL and insulin concentration. The euglycemic-hyperinsulinemic clamp test was conducted for an index of glucose infusion rates. Additionally, skeletal muscle was collected and processed for GLUT4 mRNA level and GLUT4 concentration. The present findings showed that plasma GAL levels after swimming training in all three trained groups were higher compared with each sedentary control and each preswimming level. The insulin levels after swimming in both M35 treatment groups were elevated compared with each diabetic control and each pretraining level. Moreover, M35 treatment reduced glucose infusion rates compared with each diabetic control, but swimming enhanced the rates in all trained groups compared with each sedentary control. Furthermore, M35 treatment reduced GLUT4 concentration and GLUT4 mRNA levels compared with each diabetic control. The ratio of GLUT4 contents in plasma membranes to total cell membranes in both drug groups were lower compared with each diabetic control. These results suggest that endogenous GAL may enhance GLUT4 contents and promote GLUT4 transportation from intracellular membrane pools to plasma membranes. GAL is an important hormone to regulate insulin sensitivity in skeletal muscle from type 2 diabetic rats.

A bibliometric analysis of solid waste research during the period 1993-2008.

This study is a bibliometric analysis of solid waste research to evaluate the current trends, using the literature in the Science Citation Index (SCI) database from 1993 to 2008. Analyzed aspects included document type, language, and publication output as well as distribution of journals, subject category, countries, institutes, title-words, author keywords, and 'Keywords Plus'. An evaluating indicator, h-index, was applied to characterize the solid waste publications. The trend of publication outputs during 1993-2008 coincided with a power and an exponential model. Based on the exponential model during 2001-2008, the number of articles on solid waste in 2013 is predicted to be twice that in 2008. The most common subject category is environmental science and the most productive journal is Waste Management. The USA with most publications and China with the highest growth rate were compared. Finally, author keywords, words in title, and 'Keywords Plus' were analyzed to provide research emphasis. The results showed that mainstream research was centered on the following methods: recycling, landfilling, composting and waste-to-energy. Heavy metals, fly ash and sewage sludge were considered recent research hotspots.

Survey of composition and generation rate of household wastes in Beijing, China.

It is recognized that information on both quantity and composition of residential waste is important for the effective planning of household waste handling infrastructure. In this paper, we present the results of a survey on household waste generation and composition in Beijing, China. Sample communities were selected by the integration of five indices including family population, income, age, and education. Wastes were sampled on a daily basis from 113 households in six different districts of Beijing City for ten days. The results showed that the generation rate of household wastes was 0.23 kg/pers/day. The bulk density was approximately 221 kg/m(3), and the moisture content was approximately 50%. Household waste consisted of kitchen waste, paper/cardboard, plastics, textiles, metals, glass and other wastes, the proportion of each waste was approximately 69.3%, 10.3%, 9.8%, 1.3%, 0.8%, 0.6% and 2.7%, respectively. An evaluation of the relationship between daily per capita generation of household waste and socio-economic factors indicated that household size and income both showed a negative relationship with household waste generation (kg/pers/day). As for the effect of education, families with a secondary educational level produced fewer household wastes (kg/pers/day) than those with a primary or advanced educational level.

Municipal solid waste management in Beijing City.

This paper presents an overview of municipal solid waste (MSW) management in Beijing City. Beijing, the capital of China, has a land area of approximately 1368.32 km(2) with an urban population of about 13.33 million in 2006. Over the past three decades, MSW generation in Beijing City has increased tremendously from 1.04 million tons in 1978 to 4.134 million tons in 2006. The average generation rate of MSW in 2006 was 0.85 kg/capita/day. Food waste comprised 63.39%, followed by paper (11.07%), plastics (12.7%) and dust (5.78%). While all other wastes including tiles, textiles, glass, metals and wood accounted for less than 3%. Currently, 90% of MSW generated in Beijing is landfilled, 8% is incinerated and 2% is composted. Source separation collection, as a waste reduction method, has been carried out in a total of 2255 demonstration residential and commercial areas (covering about 4.7 million people) up to the end of 2007. Demonstration districts should be promoted over a wider range instead of demonstration communities. The capacity of transfer stations and treatment plants is an urgent problem as these sites are seriously overloaded. These problems should first be solved by constructing more sites and converting to new treatment technologies. Improvements in legislation, public education and the management of waste pickers are problematic issues which need to be addressed.