Peptide hormones Research Papers - Academia.edu (original) (raw)

It is generally agreed that physiological levels of melatonin, a hormone secreted by the pineal gland, are important in protecting against oxidative stress-induced tissue damage. We investigated the effects that pinealectomy and the... more

It is generally agreed that physiological levels of melatonin, a hormone secreted by the pineal gland, are important in protecting against oxidative stress-induced tissue damage. We investigated the effects that pinealectomy and the administration of exogenous melatonin have on the brains, testes, duodena and stomachs of rats. Pinealectomized (Px) and sham-operated (non-Px) rats were used. We evaluated structural changes, and catalase (CAT), reduced glutathione (GSH), super oxide dismutase (SOD) and malondialdehyde (MDA) levels. The rats were divided into the following five groups (eight rats in each group): sham (non-Px), Px+ vehicle, Px+ melatonin (10 mg/kg given daily intraperitoneally for a week), melatonin and ethyl alcohol. The antioxidant levels in the tissue of Px rats were significantly lower than in those of the sham group. Administering melatonin significantly increased antioxidant levels (p < 0.05). The Px rats also showed a significant increase in MDA levels when com...

Phytosulfokine-α (PSK-α) is a small plant peptide (5 amino acids) that displays characteristics typically associated with animal peptide hormones. PSK-α was originally isolated based on its mitogenic activity with plant cultures; it has... more

Phytosulfokine-α (PSK-α) is a small plant peptide (5 amino acids) that displays characteristics typically associated with animal peptide hormones. PSK-α was originally isolated based on its mitogenic activity with plant cultures; it has been reported to increase production of tropane alkaloids from Atropa belladonna, although its general influence on secondary metabolite production is unknown. The studies reported in this article were initiated to evaluate the effects of PSK-α supplementation on production of Taxol™ (paclitaxel) from plant cell cultures of Taxus sp. particularly when methyl jasmonate (MeJA) is added as an elicitor of secondary metabolism. The response to PSK-α supplementation was cell line dependent. Taxus cuspidata P93AF showed no statistically significant response to PSK-α supplementation while Taxus canadensis C93AD and T. cuspidata PO93X displayed a concentration-dependent response (up to 100 nM PSK-α added in first 24 h of culture) with a decrease in initial growth rate, an increase in cell density (dry weight/fresh weight), and increased Taxol production. More remarkably with T. canadensis (C93AD), a very strong synergistic response of PSK-α (100 nM) and methyl jasmonate (MeJA, 100 µM) elicitation was observed, resulting in Taxol level of 35.3 ± 2.1 mg/L or 1.83 ± 0.02 mg Taxol/g dry cell weight achieved at day 21, a level of approximately 10-fold higher than for either treatment by itself. Although the level of Taxol production achieved is not remarkable, this synergistic treatment was able to partially revive taxane production in cultures that have lost productivity due to extended time (over 10 years) in continuous subculture. © 2006 Wiley Periodicals, Inc.

The objective of this study was to evaluate the effects of ovariectomy (i) and ad libitum feeding (ii) on energy intake, body weight (BW), body composition, thyroid status, leptin and ghrelin plasma concentrations. Four young adult female... more

The objective of this study was to evaluate the effects of ovariectomy (i) and ad libitum feeding (ii) on energy intake, body weight (BW), body composition, thyroid status, leptin and ghrelin plasma concentrations. Four young adult female Beagle dogs were fed a maintenance diet for 6 weeks prior to ovariectomy, then 6 months after. Food allowance was adjusted in order to maintain optimal BW. Then, a diet slightly higher in energy concentration was fed ad libitum for 4 months. The maintenance diet was then fed ad libitum for one additional month. The maintenance of optimal BW after ovariectomy required a significant decrease in energy allowance. No increase in fat mass was observed. Ghrelin concentration remained unchanged. During the first month of ad libitum feeding, plasma ghrelin concentration and energy intake increased, then they decreased. Mean BW, plasma leptin, thyrotropin (TSH), total triiodothyronine (TT3) and total thyroxine (TT4) concentrations significantly increased over the study. The BW increase was exclusively due to an increase in body fat. In conclusion, energy allowance should be strictly controlled in spayed female dogs. The results suggest that in dogs, thyroid hormones, leptin and ghrelin concentrations change in response to a positive energy balance in an attempt to limit weight gain. However, the significant weight gain shows that this goal was not achieved.

Diarrhea is best defined as passage of loose stools often with more frequent bowel movements. For clinical purposes, the Bristol Stool Form Scale works well to distinguish stool form and to identify loose stools. Laboratory testing of... more

Diarrhea is best defined as passage of loose stools often with more frequent bowel movements. For clinical purposes, the Bristol Stool Form Scale works well to distinguish stool form and to identify loose stools. Laboratory testing of stool consistency has lagged behind. Acute diarrhea is likely to be due to infection and to be self-limited. As diarrhea becomes chronic, it is less likely to be due to infection; duration of 1 month seems to work well as a cut-off for chronic diarrhea, but detailed scientific knowledge is missing about the utility of this definition. In addition to duration of diarrhea, classifications by presenting scenario, by pathophysiology, and by stool characteristics (e.g. watery, fatty, or inflammatory) may help the canny clinician refine the differential diagnosis of chronic diarrhea. In this regard, a careful history remains the essential part of the evaluation of a patient with diarrhea. Imaging the intestine with endoscopy and radiographic techniques is us...

There is a growing worldwide epidemic of obesity. Obese people have a higher incidence of type 2 diabetes and cardiovascular disease, and hence present increasing social, financial and health burdens. Weight loss is always difficult to... more

There is a growing worldwide epidemic of obesity. Obese people have a higher incidence of type 2 diabetes and cardiovascular disease, and hence present increasing social, financial and health burdens. Weight loss is always difficult to achieve through lifestyle changes alone, and currently licensed anti-obesity drug treatments, such as orlistat and sibutramine, if tolerated, only achieve modest weight loss. Therefore, there is a need to identify more potent pharmacological targets. In the last 10 years, discoveries of new hormones such as leptin and ghrelin, together with greater understanding of previously described hormones such as cholecystokinin (CCK), pancreatic polypeptide (PP), peptide YY (PYY) and glucagon-like peptide 1 (GLP-1), have led to a rapid increase in our knowledge of the regulation of energy balance. Among the most important factors, controlling appetite and satiety are peptide hormones released from the gut. In this paper, we provide a full up-to-date overview of the current state of knowledge of this field, together with the potential of these peptides as drugs, or as other therapeutic targets, in the treatment of obesity. Finally, we propose an integrated model to describe the complex interplay of these hormones in the broader physiology of energy balance.

Suppression of ghrelin production after Roux-en-Y gastric bypass that suggested its contribution to appetite reduction has been reported. Because biliopancreatic diversion (BPD) does not affect appetite, we compared ghrelin production and... more

Suppression of ghrelin production after Roux-en-Y gastric bypass that suggested its contribution to appetite reduction has been reported. Because biliopancreatic diversion (BPD) does not affect appetite, we compared ghrelin production and 24-h pulsatility between healthy control subjects and obese subjects before and after BPD. A computerized algorithm identified peak heights, clearance rate, and peak frequency of ghrelin over 24 h. Twenty-four-hour energy expenditure was measured in the calorimetric chamber, and energy intakes were computed. Insulin sensitivity was measured with a euglycemic-hyperinsulinemic clamp. Mean (+/-SD) 24-h plasma ghrelin concentrations were significantly (P < 0.0001) higher in control than in obese subjects (338.17 +/- 22.09 and 164.47 +/- 29.19 microg/L, respectively), but they increased to 204.64 +/- 28.51 microg/L in the obese subjects after BPD (P < 0.01). The pulsatility index was 0.098 +/- 0.016 and 0.041 +/- 0.014 microg . L(-1) . min(-1) in ...

Proteins are suspected to have a greater satiating effect than the other 2 macronutrients. After protein consumption, peptide hormones released from the gastrointestinal tract (mainly anorexigenic gut peptides such as cholecystokinin,... more

Proteins are suspected to have a greater satiating effect than the other 2 macronutrients. After protein consumption, peptide hormones released from the gastrointestinal tract (mainly anorexigenic gut peptides such as cholecystokinin, glucagon peptide 1, and peptide YY) communicate information about the energy status to the brain. These hormones and vagal afferents control food intake by acting on brain regions involved in energy homeostasis such as the brainstem and the hypothalamus. In fact, a high-protein diet leads to greater activation than a normal-protein diet in the nucleus tractus solitarius and in the arcuate nucleus. More specifically, neural mechanisms triggered particularly by leucine consumption involve 2 cellular energy sensors: the mammalian target of rapamycin and AMP-activated protein kinase. In addition, reward and motivation aspects of eating behavior, controlled mainly by neurons present in limbic regions, play an important role in the reduced hedonic response o...

Objective: To determine the effect of the initial metabolic imbalance and its restoration after insulin therapy on adiponectin and acylated ghrelin levels in children with type 1 diabetes mellitus (T1DM). Study design: Twenty prepubertal... more

Objective: To determine the effect of the initial metabolic imbalance and its restoration after insulin therapy on adiponectin and acylated ghrelin levels in children with type 1 diabetes mellitus (T1DM). Study design: Twenty prepubertal children with newly diagnosed T1DM ...

Gastrokine-1 (GKN1), a protein expressed in normal gastric tissue, but absent in gastric cancer tissues and derived cell lines, has recently emerged as a potential biomarker for gastric cancer. To better establish the molecular properties... more

Gastrokine-1 (GKN1), a protein expressed in normal gastric tissue, but absent in gastric cancer tissues and derived cell lines, has recently emerged as a potential biomarker for gastric cancer. To better establish the molecular properties of GKN1, the first protocol for the production of mature human GKN1 in the expression system of Pichia pastoris was settled. The recombinant protein showed anti-proliferative properties specifically on gastric cancer cell lines thus indicating that it was properly folded. Characterization of structural and biochemical properties of recombinant GKN1 was achieved by limited proteolysis analysis, circular dichroism and fluorescence spectroscopy. The analysis of GKN1 primary structure coupled to proteolytic experiments highlighted that GKN1 was essentially resistant to proteolytic enzymes and showed the presence of at least a disulphide bond between Cys61 and one of the other three Cys (Cys122, Cys145 and Cys159) of the molecule. The secondary structure analysis revealed a prevailing β-structure. Spectroscopic and calorimetric investigations on GKN1 thermal denaturation pointed out its high thermal stability and suggested a more complex than a two-state unfolding process. The resulting protein was endowed with a globular structure characterized by domains showing different stabilities toward chemical and physical denaturants. These results are in agreement with the prediction of GKN1 secondary structure and a three-dimensional structure model. Our findings provide the basis for the development of new pharmaceutical compounds of potential use for gastric cancer therapy.