An <Emphasis Type="Italic">Insilico</Emphasis> approach to High Altitude Pulmonary Edema - Molecular modeling of human β<Subscript>2</Subscript> adrenergic receptor and its interaction with Salmeterol &; Nifedipine

Knowledge of the three-dimensional structures of protein targets from genomic data has the potential to accelerate researches pertaining to drug discovery. Human β₂ adrenergic receptor is a G-protein-coupled receptor with seven transmembrane helices, and is important in pharmaceutical targeting on pulmonary and cardiovascular diseases. The human β₂ adrenergic receptor has been found to play a very important role in the pathogenesis of high altitude pulmonary edema (HAPE). In the present study, a high quality of protein 3D structure has been predicted for the human β₂ adrenergic receptor sequence with primary accession number P07550. Homologous template protein sequence with known 3D structure was identified and the template-query protein sequence validation was done by multiple sequence alignment method. The homology model was performed through Modeller and depended on the quality of the sequence alignment by BLAST, template structure and the consolidated result performed by Gene silico meta-server. The statistical verification of the generated model was evaluated by PROCHECK which revealed that the structure modeled through Modeller to be of good quality with 84.1% of residues in the most favored region. Docking studies were carried out after modeling with two well known ligands namely Salmeterol and Nifedipine, and the fitness score revealed that Salmeterol has a higher fitness score than Nifedipine. Estimation of binding affinity by X-Score revealed that Salmeterol had −10.40 binding affinity while Nifedipine showed −9.62 binding affinity. From the present study, it can be concluded that the generated model of human β₂ adrenergic receptor can be used for further studies related to this receptor and Salmeterol was found to have a high binding affinity with human β₂ adrenergic receptor.     

Fructose ingestion acutely elevates blood pressure in healthy young humans

Overconsumption of fructose, particularly in the form of soft drinks, is increasingly recognized as a public health concern. The acute cardiovascular responses to ingesting fructose have not, however, been well-studied in humans. In this randomized crossover study, we compared cardiovascular autonomic regulation after ingesting water and drinks containing either glucose or fructose in 15 healthy volunteers (aged 21-33 yr). The total volume of each drink was 500 ml, and the sugar content 60 g. For 30 min before and 2 h after each drink, we recorded beat-to-beat heart rate, arterial blood pressure, and cardiac output. Energy expenditure was determined on a minute-by-minute basis. Ingesting the fructose drink significantly increased blood pressure, heart rate, and cardiac output but not total peripheral resistance. Glucose ingestion resulted in a significantly greater increase in cardiac output than fructose but no change in blood pressure and a concomitant decrease in total peripheral resistance. Ingesting glucose and fructose, but not water, significantly increased blood pressure variability and decreased cardiovagal baroreflex sensitivity. Energy expenditure increased by a similar amount after glucose and fructose ingestion, but fructose elicited a significantly greater increase in respiratory quotient. These results show that ingestion of glucose and fructose drinks is characterized by specific hemodynamic responses. In particular, fructose ingestion elicits an increase in blood pressure that is probably mediated by an increase in cardiac output without compensatory peripheral vasodilatation.     

Cloning and tissue distribution of a carnitine palmitoyltransferase I gene in rainbow trout (Oncorhynchus mykiss)

The carnitine palmitoyltransferase I (EC.2.3.1.21; CPT I) mediates the transport of fatty acids across the outer mitochondrial membrane. In mammals, there are two different proteins CPT I in the skeletal muscle (M) and liver (L) encoded by two genes. The carnitine palmitoyltransferase system of lower vertebrates received little attention. With the aim of improving knowledge on the CPT family in fish, we examined CPT I cDNA and CPT activity in different tissues of rainbow trout (Oncorhynchus mykiss). Using RT-PCR, we successfully cloned a partial CPT I cDNA sequence (1650 bp). The predicted protein sequence revealed identities of 63% and 61% with human L-CPT I and M-CPT I, respectively. This mRNA is expressed in liver, white and red skeletal muscles, heart, intestine, kidney and adipose tissue of trout. This is in good agreement with the measurement of the CPT activity in the same tissues. The [IC(50)] that reflects the sensitivity to malonyl-CoA inhibition was 0.116+/-0.004 microM for the liver and 0.426+/-0.041 microM for the white muscle. These results demonstrate for the first time the existence of at least one gene encoding for CPT I present in both the liver and the muscle of rainbow trout.     

Effect of onion (Allium cepa Linn.) and garlic (Allium sativum Linn.) on plasma triglyceride content in Japanese quail (Coturnix coturnix japonicum)

Dietary onion and garlic caused an increase in the level of plasma triglyceride which could be due to insulin like activity of dietary alliums and other factors that promote lipogenesisi in growing stages. Changes in the plasma triglyceride level in the control group due to change in age and sex were also noted. The triglyceride level was more in female birds when compared to males of similar age group. The plasma trigelyceride level increased with age in both sex except for the level being similar in the 6 and 9-week old females and 3 and 6-week old male birds. The results suggest that the effects of alliums in growing and adult stages may be different which needs further study.     

Muscle insulin binding and plasma levels in relation to liver glucokinase activity,glucose metabolism and dietary carbohydrates in rainbow trout

Rainbow trout were fed for 10 weeks with either a carbohydrate-free diet (C-free) or with four experimental diets containing various levels (20 or 40%) and sources of starch (extruded wheat or peas) in order to examine metabolic utilisation of dietary vegetable carbohydrates and its endocrine control. The study was focused on the parameters described as limiting in glucose metabolism in fish. Feeding trials were conducted at 8 and 18 degrees C to establish whether carbohydrate-rich diets can be used in trout farming irrespective of water temperature. At both temperatures, pea diets (especially the highest level) resulted in a feed efficiency as high as the C-free diet. Fish had similar growth rates except when fed the low wheat content diet. Glycaemia values 6 h after feeding were significantly higher in trout fed carbohydrate diets than those given the C-free diet, whereas plasma insulin levels were similar independently of the levels of dietary starch. This study provides the first evidence that glucokinase (GK) activity and mRNA level in trout liver increase in proportion to the content of dietary starch. Nevertheless, these changes were not correlated with plasma insulin levels. Insulin-like growth factor-I (IGF-I) binding and number of receptors in skeletal muscle were consistently higher than those for insulin but no diet-induced differences were found for any of these parameters. Temperature clearly affected the postprandial profile of glucose and insulin, which both showed lower levels 6 h after feeding at 8 degrees C than at 18 degrees C, which was consistent with a lower feed intake. Glucose and insulin levels decreased markedly 24 h after feeding at 18 degrees C, while they were still high at 8 degrees C, an observation concordant with delayed transit rate. These findings indicate satisfactory adaptation of rainbow trout to diets with a relatively high vegetable starch content, especially when provided as extruded peas, and indicate that diets with increased levels of carbohydrates can be used in this species even when it is reared at low temperature.     

Response of hexokinase enzymes and the insulin system to dietary carbohydrates in the common carp, Cyprinus carpio

The response of the common carp to diets with varying amounts of digestible starch, provided either as pea meal (LP, HP, 30 and 46% peas, respectively) or as cereal (LW, HW, 30 and 46% wheat, respectively), was studied and compared with the response to a carbohydrate-free protein-rich diet (CF). Here we focused on the utilisation of dietary carbohydrates by examining the relationship between dietary starch intake, hepatic hexokinase activities, circulating insulin and muscle insulin receptor system. Plasma glucose concentration and hepatic high Km hexokinase (glucokinase, GK) activity were not affected by the content of digestible starch, but 6 h after feeding enzyme activity was higher in the fish fed carbohydrate diets. Similarly, low Km hexokinase (HK) activity was also higher in the fish 24 h after feeding. Fat gain and protein retention were significantly improved by increased digestible starch intake, especially in the HP group, which in turn, presented the highest plasma insulin levels. Glycogen stores were moderately increased by the ingestion of digestible starch. The number of insulin receptors was greater in the CF group than in fish on carbohydrates, except the HP group. Our results confirmed that the common carp uses dietary carbohydrates efficiently, especially when there are provided by peas. This efficiency might be related to the enhanced response of postprandial insulin observed in the HP group.     

Nutritional assessment of somatolactin function in gilthead sea bream (Sparus aurata): concurrent changes in somatotropic axis and pancreatic hormones

The role of somatolactin (SL) in the regulation of energy homeostasis in gilthead sea bream (Sparus aurata) has been analysed. First, a down-regulation of plasma SL levels in response to gross shifts in dietary amino acid profile and the graded replacement of fish meal by plant protein sources (50%, 75% and 100%) has been observed. Thus, the impaired growth performance with changes in dietary amino acid profile and dietary protein source was accompanied by a decrease in plasma SL levels, which also decreased over the course of the post-prandial period irrespective of dietary nitrogen source. Secondly, we examined the effect of SL and growth hormone (GH) administration on voluntary feed intake. A single intraperitoneal injection of recombinant gilthead sea bream SL (0.1 microg/g fish) evoked a short-term inhibition of feed intake, whereas the same dose of GH exerted a marked enhancement of feed intake that still persisted 1 week later. Further, we addressed the effect of arginine (Arg) injection upon SL and related metabolic hormones (GH, insulin-like growth factor-I (IGF-I), insulin and glucagon) in fish fed diets with different nitrogen sources. A consistent effect of Arg injection (6.6 micromol/g fish) on plasma GH and IGF-I levels was not found regardless of dietary treatment. In contrast, the insulinotropic effect of Arg was found irrespective of dietary treatment, although the up-regulation of plasma glucagon and glucose levels was more persistent in fish fed a fish meal based diet (diet FM) than in those fed a plant protein diet with a 75% replacement (diet PP75). In the same way, a persistent and two-fold increase in plasma SL levels was observed in fish fed diet FM, whereas no effect was found in fish fed diet PP75. Taken together, these findings provide additional evidence for a role of SL as a marker of energy status, which may be perceived by fish as a daily and seasonal signal of abundant energy at a precise calendar time.     

Juvenile hormone activity in Dysdercus cingulatus Fabr by juvenile hormone esterase inhibitor, OTFP

Application of juvenile hormone esterase inhibitor 3-octylthio-1,1,1- trifluropropan-2-one (OTFP) to 5th instar nymphs and virgin females of D. cingulatus revealed the profound role played by juvenile hormone esterase (JHE) in metamorphosis and reproduction. The ability of OTFP to cause delay and the formation of malformed nymphs, suggests that inhibition of JHE in vivo maintains a higher than normal hemolymph JH titer. It is obvious that OTFP does inhibit in vivo JHE activity in late instar nymphs. Further, the application of JHE inhibitor, OTFP to virgin females demonstrates that substituted trifluropropanones can indirectly stimulate egg development by inhibiting JHE activity in virgin females.