Postprandial hepatic protein expression in trout Oncorhynchus mykiss a proteomics examination

Following a meal, a series of physiological changes occurs in animals as they digest, absorb and assimilate ingested nutrients, the kinetics of these responses depends on metabolic rate and nutrient quality. Here we investigated the hepatic proteome in the ectothermic teleost, the rainbow trout, following a single meal to define the postprandial expression of hepatic proteins. The fish were fed a high marine fishmeal/fish oil single meal following a period of 24 h without feeding. Liver protein profiles were examined by 2D gel electrophoresis just before feeding (time 0 h) and at 6 and 12 h after feeding. Of a total of 588 protein spots analysed in a temporal fashion, 49 differed significantly in abundance between the three time groups (ANOVA, p<0.05), before and after feeding, 15 were increased and 34 were decreased in abundance after feeding. Amino acid metabolism-regulated proteins such as phenylalanine-4-hydroxylase and proliferating cell antigen were increased in abundance 12 and 6 h following the meal, suggesting by this time that the fish were increasing their protein turnover to utilize efficiently their dietary protein consumption. Overall, these results highlight some specificity of the trout metabolism and identify postprandial response of metabolism-related proteins 6–12 h after feeding a single meal.     

Antioxidant system response is modified by dietary fat in adipose tissue of metabolic syndrome patients

Metabolic syndrome (MetS) is associated with high oxidative stress, which is caused by an increased expression of NADPH-oxidase and a decreased expression of antioxidant enzymes in the adipose tissue. Our aim was to evaluate whether the quality and quantity of dietary fat can modify that process. A randomized, controlled trial conducted within the LIPGENE study assigned MetS patients to one of four diets for 12 wk each: (i) high-saturated fatty acid (HSFA), (ii) high-monounsaturated fatty acid (HMUFA), (iii) and (iv) two low-fat, high-complex carbohydrate diet supplemented with n-3 polyunsaturated fatty acids (LFHCC n3), or placebo (LFHCC). A fat challenge reflecting the same fatty acid composition as the original diets was conducted post-intervention. The intake of an HSFA meal induced a higher postprandial increase in gp91phox and p67phox mRNA levels than after the intake of HMUFA, LFHCC and LFHCC n-3 meals (all p-values < 0.05). The postprandial decrease in CAT, GPXs and TXNRD1 mRNA levels after the HSFA meal intake was higher than after the intake of HMUFA, LFHCC and LFHCC n-3 meals (all p-values < 0.05). The intake of an HSFA meal induced a higher postprandial increase in KEAP1 mRNA levels than after the consumption of the HMUFA (P = .007) and LFHCC n-3 (P = .001) meals. Our study demonstrated that monounsaturated fat consumption reduces oxidative stress as compared to saturated fat by inducing higher postprandial antioxidant response in adipose tissue, and thus, replacing SFA for MUFA may be an effective dietary strategy to reduce the oxidative stress in MetS patients and its pathophysiological consequences.     

Plasma nitrate/nitrite levels are unchanged after long-term aerobic exercise training in older adults

Reduced nitric oxide (NO) production and bioactivity is a major contributor to endothelial dysfunction. Animal data suggest that improvements in endothelial function in response to aerobic exercise training may depend on the duration of the training program. However, no studies have examined changes in NO (as assessed by the major NO metabolites, nitrate and nitrite, NO_x) after long-term training in humans. In addition, aging may impair the ability of the vasculature to increase NO with exercise. Thus, we determined whether 24 weeks of aerobic exercise training increases plasma NO_x levels in sedentary older adults. We also examined changes in forearm blood flow (FBF) at rest and during reactive hyperemia as a measure of vasomotor function. Plasma NO_x levels were measured in 82 men and women using a modified Griess assay. FBF was assessed in a subset of individuals (n = 15) using venous occlusion plethysmography. After 24 weeks of exercise training, there were significant improvements in maximum oxygen consumption, HDL cholesterol, triglycerides, and body fat. Changes in plasma NO_x levels ranged from ?14.83 to +16.69 μmol/L; however, the mean change overall was not significant (?0.33 ± 6.30 μmol/L, p = 0.64). Changes in plasma NO_x levels were not associated with age, gender, race, HDL cholesterol, triglycerides, body weight, body fat, or maximal oxygen consumption. There were also no significant changes in basal FBF, peak FBF, hyperemic response, total hyperemic flow, or minimum forearm vascular resistance with exercise training. In conclusion, improvements in plasma NO_x levels and FBF are not evident after long-term training in older adults.     

Effects of cefaclor on gastric emptying and cholecystokinin release in healthy humans

Background and aimsIn rodents, cephalosporin antibiotics can mimic peptones and stimulate release of cholecystokinin (CCK), a hormone that slows gastric emptying. The rate of gastric emptying is a major determinant of postprandial blood glucose and insulin concentrations. We therefore evaluated the effect of orally administered cefaclor on plasma CCK and gastric emptying, as well as postprandial glycemic and insulinemic responses, in healthy humans.Materials and methodsWe studied 8 healthy subjects on two days in double-blind, randomized order. On each day, subjects consumed 1000 mg cefaclor or placebo 30 min before a mashed potato meal labeled with ¹³C octanoic acid. Blood and breath samples were collected for 4 h after the meal.ResultsBlood glucose, serum insulin and plasma CCK increased in response to the carbohydrate meal on both study days, and cefaclor had no effect on these responses. Similarly, the gastric half-emptying time (measured by breath test) did not differ (placebo: 137.5 ± 6.0 min vs. cefaclor: 143.1 ± 8.0 min).ConclusionCefaclor, when given before a meal in the form of a capsule, does not stimulate CCK release or slow gastric emptying in healthy humans.     

Time-course of changes in plasma nitric oxide following lipopolysaccharide and turpentine injection in rats

The effect of lipopolysaccharide (LPS) and turpentine on nitric oxide (NO) production were investigated in rats. Because of short half-life of NO in biological fluids, the plasma nitrite and nitrate concentrations (two stabile metabolites of NO) were measured based on Griess reaction, which is indirect assay for NO production. Injection of LPS at an intraperitoneal dose of 50 μg/kg caused a 3,5-fold increase in plasma nitrite within 3 h and nitrite levels remained significantly elevated 6, 12, and 24 h after endotoxin treatment with LPS. However, injection of turpentine at an intramuscular dose of 20 μl/rat did not alter plasma nitrite concentration at selected times after turpentine treatment (7, 10, 14, and 24 h postinjection). These results further support the hypothesis that NO is involved in pathogenesis of febrile response due to LPS in rats. Because turpentine did not change concentration of NO in plasma, the role of NO, as mediator/modulator, in development of turpentine fever appears to be controversial and needs further experimental verification.     

Ghrelin protects human pulmonary artery endothelial cells against hypoxia-induced injury via PI3-kinase/Akt

Endothelial injury and diminished NO release induced by hypoxia is thought to be a critical factor in the development of pulmonary artery hypertension (PAH). Ghrelin (Ghr) is a well-characterized hormone and has protective effects on the cardiovascular system, specifically by promoting the vascular endothelial cell function. The aim of this study was to investigate the effect of the Ghr on the hypoxia-induced injury in human pulmonary artery endothelial cells (HPAECs) and on the involved transduction pathway. Effects were investigated by treating cells with varying concentrations of Ghr in the absence or presence of inhibitors that target phosphoinositide 3-kinase (PI3K), in normoxic or hypoxic conditions for 24 h. Our results indicated that the treatment with 10⁻⁷ mol/l Ghr significantly enhanced cell viability (P < 0.05, n = 5) and upregulated the ratio of Bcl-2/Bax under hypoxic condition (P < 0.05, n = 4), as compared with the hypoxic condition alone. However, an addition of the PI3K/Akt inhibitor LY294002 inhibited these Ghr-mediated effects. Moreover, the Ghr (10⁻⁷ mol/l) significantly increased NO secretion and eNOS phosphorylation in comparison with the hypoxia or normoxia alone group (P < 0.05, n = 4). Nevertheless, the treatment with LY294002 (20 μ mol/l) decreased the Ghr-induced NO release as well as the eNOS activity. In conclusion, the Ghr could inhibit hypoxia-mediated HPAECs dysfunction via the PI3K/Akt pathway, and the bcl-2/bax ratio was also involved in the protective action of the Ghr in HPAECs. As such, the Ghr demonstrates a significant potential to prevent and treat PAH affected by the endothelial dysfunction.     

Preventive effect of rikkunshito on gastric motor function inhibited by l-dopa in rats

We previously reported that ghrelin prevented l-dopa (LD)-induced inhibition of gastric emptying (GE) of a non-nutrient solution in rats. Parkinson's disease treatment involves the combined administration of l-dopa with the enzyme l-amino acid decarboxylase inhibitor, carbidopa (CD) to reduce peripheral formation of dopamine. We investigated the effect LD/CD given orogastrically (og) on GE of a non-nutrient or nutrient meal and whether og pretreatment with rikkunshito, a kampo medicine clinically used to treat gastroparesis, influenced LD/CD effect on GE and postprandial antral and duodenal motility in conscious rats. LD/CD (20/2 mg kg⁻¹) decreased significantly GE to 26.3 ± 6.0% compared to 61.2 ± 3.2% in og vehicle monitored 20-min after a non-nutrient meal and to 41.9 ± 5.8% compared to 72.9 ± 5.2% in og vehicle monitored 60 min after a nutrient meal. Rikkunshito (0.5 or 1.0 g kg⁻¹) reduced the LD/CD (20/2 mg kg⁻¹) inhibition of GE of non-nutrient meal (36.9 ± 7.4% and 46.6 ± 4.8% respectively vs. 12.1 ± 7.4% in og vehicle plus LD/CD) while having no effect alone (56.6 ± 8.5%). The ghrelin antagonist, [d-Lys³]-GHRP-6 (1 mg kg⁻¹) injected intraperitoneally partially reversed rikkunshito preventive effect on LD/CD-inhibited GE. Rikkunshito (1.0 g kg⁻¹) blocked LD/CD (20/2 mg kg⁻¹)-induced delayed GE of a nutrient meal and the reduction of postprandial antral motility. In 6-hydroxydopamine-induced Parkinson's disease rat model, rikkunshito (1.0 g kg⁻¹, og) also prevented LD/CD-inhibited gastric emptying of a nutrient meal and enhanced fasting plasma levels of acylated ghrelin. These data indicate that oral rikkunshito alleviates the delayed GE induced by LD/CD in naïve and PD rat model in part through ghrelin-related mechanisms.     

Interactions between cocoa flavanols and inorganic nitrate: Additive effects on endothelial function at achievable dietary amounts

Dietary intervention studies have shown that flavanols and inorganic nitrate can improve vascular function, suggesting that these two bioactives may be responsible for beneficial health effects of diets rich in fruits and vegetables. We aimed to study interactions between cocoa flavanols (CF) and nitrate, focusing on absorption, bioavailability, excretion, and efficacy to increase endothelial function. In a double-blind randomized, dose–response crossover study, flow-mediated dilation (FMD) was measured in 15 healthy subjects before and at 1, 2, 3, and 4 h after consumption of CF (1.4–10.9 mg/kg bw) or nitrate (0.1–10 mg/kg bw). To study flavanol–nitrate interactions, an additional intervention trial was performed with nitrate and CF taken in sequence at low and high amounts. FMD was measured before (0 h) and at 1 h after ingestion of nitrate (3 or 8.5 mg/kg bw) or water. Then subjects received a CF drink (2.7 or 10.9 mg/kg bw) or a micro- and macronutrient-matched CF-free drink. FMD was measured at 1, 2, and 4 h thereafter. Blood and urine samples were collected and assessed for CF and nitric oxide (NO) metabolites with HPLC and gas-phase reductive chemiluminescence. Finally, intragastric formation of NO after CF and nitrate consumption was investigated. Both CF and nitrate induced similar intake-dependent increases in FMD. Maximal values were achieved at 1 h postingestion and gradually decreased to reach baseline values at 4 h. These effects were additive at low intake levels, whereas CF did not further increase FMD after high nitrate intake. Nitrate did not affect flavanol absorption, bioavailability, or excretion, but CF enhanced nitrate-related gastric NO formation and attenuated the increase in plasma nitrite after nitrate intake. Both flavanols and inorganic nitrate can improve endothelial function in healthy subjects at intake amounts that are achievable with a normal diet. Even low dietary intake of these bioactives may exert relevant effects on endothelial function when ingested together.     

Loneliness predicts postprandial ghrelin and hunger in women

Loneliness is strongly linked to poor health. Recent research suggests that appetite dysregulation provides one potential pathway through which loneliness and other forms of social disconnection influence health. Obesity may alter the link between loneliness and appetite-relevant hormones, one unexplored possibility. We examined the relationships between loneliness and both postmeal ghrelin and hunger, and tested whether these links differed for people with a higher versus lower body mass index (BMI; kg/m²). During this double-blind randomized crossover study, women (N = 42) ate a high saturated fat meal at the beginning of one full-day visit and a high oleic sunflower oil meal at the beginning of the other. Loneliness was assessed once with a commonly used loneliness questionnaire. Ghrelin was sampled before the meal and postmeal at 2 and 7 h. Self-reported hunger was measured before the meal, immediately postmeal, and then 2, 4, and 7 h later. Lonelier women had larger postprandial ghrelin and hunger increases compared with less lonely women, but only among participants with a lower BMI. Loneliness and postprandial ghrelin and hunger were unrelated among participants with a higher BMI. These effects were consistent across both meals. These data suggest that ghrelin, an important appetite-regulation hormone, and hunger may link loneliness to weight gain and its corresponding negative health effects among non-obese people.     

The influence of feeding and fasting on plasma metabolites in the dogfish shark (Squalus acanthias)

Dogfish sharks are opportunistic predators, eating large meals at irregular intervals. Here we present a synthesis of data from several previous studies on responses in plasma metabolites after natural feeding and during prolonged fasting (up to 56 days), together with new data on changes in plasma concentrations of amino acids and non-esterified fatty acids. Post-prandial and long-term fasting responses were compared to control sharks fasted for 7 days, a typical inter-meal interval. A feeding frenzy was created in which dogfish were allowed to feed naturally on dead teleosts at two consumed ration levels, 2.6% and 5.5% of body weight. Most responses were more pronounced at the higher ration level. These included increases in urea and TMAO concentrations at 20 h, followed by stability through to 56 days of fasting. Ammonia levels were low and exhibited little short-term response to feeding, but declined to very low values during the extended fast. Glucose and β-hydroxybutyrate both fell after feeding, the latter to a greater and more prolonged extent (up to 60 h), whereas acetoacetate did not change. During prolonged fasting, glucose concentrations were well regulated, but β-hydroxybutyrate increased to 2–3-fold control levels. Total plasma amino acid concentrations increased in a biphasic fashion, with peaks at 6–20 h, and 48–60 h after the meal, followed by homeostasis during the extended fast. Essential and non-essential amino acids generally followed this same pattern, though some exhibited different trends after feeding: taurine, β-alanine, and glycine (decreases or stability), alanine and glutamine (modest prolonged increases), and threonine, serine, asparagine, and valine (much larger short-term increases). Plasma non-esterified fatty acid concentrations declined markedly through 48 h after the 2.6% meal. These data are interpreted in light of companion studies showing elevations in aerobic metabolic rate, urea production, rectal gland function, metabolic base excretion, and activation of ornithine–urea cycle and aerobic enzymes after the meal, and muscle N-depletion but maintenance of osmolality and urea production during long-term fasting.     

Feeding soybean meal increases the blood level of isoflavones and reduces the steroidogenic capacity in bovine corpora lutea,without affecting peripheral progesterone concentrations

Thirty-three Holstein-Friesian cows were followed from 14 days pre partum until the fourth ovulation post partum. Housing conditions and basic ration were identical for all animals. Concentrates were individually supplemented according to the daily milk production level, using two different types of protein rich concentrates: soybean meal and rapeseed meal. Soybean and rapeseed meal are known to be respectively high and low in isoflavones. Cows were randomly divided into three groups and blocked for parity. Group I (n = 11) was supplemented with soybean meal and acted as control group. Groups II (n = 11) and III (n = 11) were respectively supplemented with soybean and rapeseed meal and were subjected to a biopsy sampling of the corpus luteum at day 9 of the first three postpartal estrous cycles.Soybean meal supplementation to lactating dairy cows (1.72 kg on average) induced an increase in the blood concentration of equol, dihydrodaidzein, o-desmethylangolensin in both soy groups and resulted in a reduced area occupied by steroidogenic (P = 0.012) and endothelial cells (P = 0.0007) in the luteal biopsies. Blood concentrations of equol and glycitein were negatively correlated with the areas occupied by steroidogenic (r = −0.410 with P = 0.0002, respectively r = −0.351 with P = 0.008) and endothelial cells (r = −0.337 with P = 0.01, respectively r = −0.233 with P = 0.085) in the 3 first estrous cycles. The latter however did not affect the diestrous peripheral blood progesterone concentration.     

The mechanism underlying the appearance of late apoptotic neutrophils and subsequent TNF-α production at a late stage during Staphylococcus aureus bioparticle-induced peritoneal inflammation in inducible NO synthase-deficient mice

During inflammation, neutrophils infiltrate into the involved site and undergo apoptosis. Early apoptotic neutrophils are then cleared by phagocytes, leading to resolution of the inflammation, whereas if late apoptotic neutrophils are accumulated for some reason, they provoke proinflammatory responses such as TNF-α production. To determine how endogenously produced nitric oxide (NO) regulates neutrophil apoptosis and the resolution of inflammation, we compared peritoneal inflammation induced by Staphylococcus aureus bioparticles in wild type mice with that in inducible NO synthase (iNOS)-deficient ones. In this model, NO production was largely dependent on iNOS, the NO level peaking at 24 h. There were increases in the numbers of neutrophils and late apoptotic ones at 24 h in iNOS-deficient mice as compared with in wild type ones, and consequently TNF-α production at 36 h in iNOS-deficient mice. On the other hand, the administration of a NO donor to iNOS-deficient mice at 12 h decreased the numbers of neutrophils and late apoptotic ones at 24 h, and thereafter TNF-α production at 36 h. In addition, coculturing of macrophages with late apoptotic neutrophils caused TNF-α production and a NO donor inhibited the transmigration of neutrophils in a dose-dependent manner. Collectively, these results suggest a novel mechanism that endogenously produced NO suppresses neutrophil accumulation at a late stage of inflammation, thereby preventing the appearance of late apoptotic neutrophils and subsequent proinflammatory responses.     

Postprandial profiles of CCK after high fat and high carbohydrate meals and the relationship to satiety in humans

ContextCCK is understood to play a major role in appetite regulation. Difficulties in measuring CCK have limited the potential to assess its profile in relation to food-induced satiety. Improvements in methodology and progress in theoretical understanding of satiety/satiation make it timely for this to be revisited.ObjectiveFirst, examine how physiologically relevant postprandial CCK8/33(s) profiles are influenced by fat (HF) or carbohydrate (HCHO) meals. Second, to examine relationships between postprandial CCK and profiles of satiety (hunger/fullness) and satiation (meal size).Participants and designSixteen overweight/obese adults (11 females/5 males) participated in a randomised-crossover study (46 years, 29.8 kg/m²) in a university research centre. Plasma was collected preprandially and for 180 min postprandially. Simultaneously, ratings of hunger/fullness were tracked for 180 min before an ad libitum lunch was provided.ResultsCCK8/33(s) levels increased more rapidly and reached a higher peak following HF compared to HCHO breakfast (F_(1,15) = 14.737, p < 0.01). Profiles of hunger/fullness did not differ between conditions (F_(1,15) = 0.505, p = 0.488; F_(1,15) = 2.277, p = 0.152). There was no difference in energy intake from the ad libitum meal (HF-3958 versus HCHO-3925 kJ; t₍₁₄₎ = 0.201, p = 0.844). CCK8/33(s) profiles were not associated with subjective appetite during early and late phases of satiety; nor was there an association between CCK8/33(s) and meal size.ConclusionsThese results demonstrate CCK levels were higher after HF meal compared to HCHO isocaloric meal. There was no association between CCK levels and intensity of satiety, or with meal size. Under these circumstances, CCK does not appear to play a unique independent role in satiety/satiation. CCK probably acts in conjunction with other peptides and the action of the stomach.     

Combined effect of bone marrow derived mesenchymal stem cells and nitric oxide inducer on injured gastric mucosa in a rat model

AimTo study the effect of intravenous injection of bone marrow mesenchymal stem cells (BMMSCs), alone and combined with NO inducer in gastric ulcer healing in a rat model.MethodsRats were divided into controls, gastric ulcer, gastric ulcer receiving mesenchymal stem cells (MSCs), gastric ulcer receiving NO inducer (l-Arginine), gastric ulcer receiving MSCs plus NO inducer (l-Arginine) groups. MSCs were given in a dose of (10⁶cells) by intravenous injection. l-Arginine was given 300 mg/kg body weight intraperitoneally. 24 h and 7 days after BMMSCs and NO inducer injection, VEGF, PGE, TNF-α were assessed by ELISA. Gene expression of HGF, caspase-3, eNOS and BAX/Bcl-2 in gastric tissues were studied by real time PCR. Histopathology staining of gastric tissues was performed.ResultsInjection of MSCs or NO inducer or both to the gastric ulcer group significantly decreased caspase-3 and BAX genes expression (apoptotic factors) and increased Bcl-2 gene expression (anti-apoptotic factor) compared to that of the gastric ulcer group after both 24 h and 7 days with more significant results in the gastric group received both MSCs and NO inducer. HGF gene expression was significantly increased in the groups injected with MSCs or NO inducer or both compared with the corresponding gastric ulcer group (p < 0.05, p < 0.05 & p < 0.001 respectively). There was a significant decrease in the mean PGE2 and TNF-α levels in the gastric ulcer group receiving MSCs, the gastric ulcer group receiving NO and the gastric ulcer group receiving both MSCs and  NO compared to the gastric ulcer group after both 24 h and 7 days. Histopathological examination of gastric tissue of groups that received stem cells or NO alone, showed mucosal regenerative changes with increased thickness together with reduced inflammatory cellular infiltrate in the submucosa and decreased congestion. There was complete restoration in gastric mucosa in the group that received both stem cells and NO.ConclusionAdministration of MSCs, NO, or MSCs plus NO may exert a therapeutic effect on the mucosal lesion in gastric ulcer through their anti-inflammatory, angiogenic and antiapoptotic actions.     

Evaluation of a two-stage in vitro technique for estimating digestibility of equine feeds using horse faeces as the source of microbial inoculum

To develop a two-stage in vitro technique that simulates both pre-caecal and hind gut digestion processes, four enzymatic pre-digestion treatments by pepsin and α-amylase (ET0 = control, ET1 = 2 h pepsin + 2 h amylase, ET2 = 2 h pepsin + 4 h amylase, ET3 = 8 h pepsin + 16 h amylase) were tested on oat hay (OH), barley grain (BG) and soybean meal (SBM). Investigated parameters were enzymatic organic matter digestibility (OMDe), and gas production (G48h, G72h) and OM digestibility (OMD) using horse faeces as a source of microbial inoculum.Enzymatic pre-digestion treatments affected (P<0.05) investigated parameters and their ranking differed among feeds. Only OMD of BG and SBM were higher after the pre-digestion treatment. OMD prior to (ET0) and after ET3 application were, successively, 0.357 versus 0.351 (OH), 0.71 versus 0.79 (BG) and 0.70 versus 0.78 (SBM). Net gas production overestimated fermentation potential of non-pre-digested feeds. G72h (ml/g DM) prior to (ET0) and after ET3 application were, successively, 80.3 versus 58.0 (OH), 151.7 versus 30.4 (BG) and 110.6 versus 37.7 (SBM).It was concluded that the enzymatic pre-digestion treatments effects varied among tested feeds, and that the suggested procedure be extended and validated with a large array of feeds of known digestibility values.     

Nitric oxide enhances osteoclastogenesis possibly by mediating cell fusion

Osteoclasts are multinucleated bone resorbing cells which form by fusion of pre-osteoclasts. Here, we investigate how nitric oxide (NO) affects osteoclastogenesis. Time lapse photomicrography, using the fluorescent NO indicator dye, 4,5-diaminofluorescein diacetate, revealed an intense NO signal in pre-osteoclasts preceding cell fusion. Osteoclastogenesis in RAW264.7 cells increased when exposed to the NO synthase inhibitor, l-NMMA (0.25 μM), for the initial 48 h. In contrast, pre-osteoclast fusion decreased when RAW264.7 cells were exposed to l-NMMA from 48 to 96 h. Both NO synthase inhibitors, l-NMMA and l-NAME, decreased osteoclast formation during this time period. The inhibitory effect of l-NMMA on osteoclast formation was abolished with increasing concentrations (25–200 ng/ml) of sRANKL suggesting signaling cross talk. NO donors increased osteoclast formation in a dose-dependent manner, with greatest stimulation at 15 μM NOC-12 (2.3 fold) and 5 μM NOC-18 (2.4 fold). Measuring nitrite (NO end product) daily from culture media of RAW264.7 cells undergoing osteoclastogenesis revealed that an increase in NO production coincided with the fusion of pre-osteoclasts (day 4). Inhibiting fusion by plating cells on polystyrene dishes pre-coated with poly-(l-lysine) decreased both osteoclast formation and NO production. To address if NO mediates fusion through the actin cytoskeleton, actin free barbed ends were measured. 0.25 μM l-NMMA decreased, while 15 μM NOC-12 and 5 μM NOC-18 increased actin free barbed ends. We hypothesize that while NO initially negatively regulates pre-osteoclast differentiation; it later facilitates the fusion of mononuclear pre-osteoclasts, possibly by up regulating actin remodeling.     

The effect of encapsulated glutamine on gut peptide secretion in human volunteers

ContextWeight loss and improved blood glucose control after bariatric surgery have been attributed in part to increased ileal nutrient delivery with enhanced release of glucagon-like peptide 1 (GLP-1). Non-surgical strategies to manage obesity are required. The aim of the current study was to assess whether encapsulated glutamine, targeted to the ileum, could increase GLP-1 secretion, improve glucose tolerance or reduce meal size.MethodsA single-center, randomised, double blind, placebo-controlled, cross-over study was performed in 24 healthy volunteers and 8 patients with type 2 diabetes. Fasting participants received a single dose of encapsulated ileal-release glutamine (3.6 or 6.0 g) or placebo per visit with blood sampling at baseline and for 4 h thereafter. Glucose tolerance and meal size were studied using a 75 g oral glucose tolerance test and ad libitum meal respectively.ResultsIn healthy volunteers, ingestion of 6.0 g glutamine was associated with increased GLP-1 concentrations after 90 min compared with placebo (mean 10.6 pg/ml vs 6.9 pg/ml, p = 0.004), increased insulin concentrations after 90 min (mean 70.9 vs 48.5, p = 0.048), and increased meal size at 120 min (mean 542 g eaten vs 481 g, p = 0.008). Ingestion of 6.0 g glutamine was not associated with significant differences in GLP-1, glucose or insulin concentrations after a glucose tolerance test in healthy or type 2 diabetic participants.ConclusionsSingle oral dosing of encapsulated glutamine did not provoke consistent increases in GLP-1 and insulin secretion and was not associated with beneficial metabolic effects in healthy volunteers or patients with type 2 diabetes.     

A possible correlation between the correction of endothelial dysfunction and normalization of high blood pressure levels by 1,3,4-oxadiazole derivative,an L-type Ca2+ channel blocker in deoxycorticosterone acetate and NG-nitro-l-arginine hypertensive rats

We have previously demonstrated the vasorelaxant activity of 1,3,4-oxadiazole derivative (NOX-1) through L-type Ca²⁺ channel blockage. In the present study, we investigated whether the correction of endothelial dysfunction is dependent on the normalization of high blood pressure levels by 1,3,4-oxadiazole derivative (NOX-1) in deoxycorticosterone acetate (DOCA-salt) and N^G-nitro-l-arginine (L-NNA) hypertensive rats. In DOCA-salt and L-NNA hypertensive rats, the mean systolic blood pressure (MSBB) was 185.3 ± 4.7 and 170.2 ± 4.1 mmHg, whereas after administration of NOX-1 to hypertensive rats, MSBB was 127.8 ± 4.5 and 120.2 ± 5.1 mmHg, respectively. To study the endothelial dysfunction, concentration–response curves of norepinephrine (NE) and acetylcholine (Ach) were constructed in rat aortic rings isolated from normotensive, hypertensive (DOCA and L-NNA) and NOX-1 treated rats. NE-induced contractions and Ach-induced relaxations were significantly (p < 0.05) decreased and increased, respectively in the aorta of NOX-1 treated rats. Vasorelaxant activity of NOX-1 was not abolished by pretreatment of aortic rings with L-NNA, 1H-[1,2,4] oxadiazolo [4,3-A] quinoxalin-1-one (ODQ), indomethacin or glibenclamide. The results suggest that the endothelial dysfunction can be corrected by the L-type Ca²⁺ channel blocker with endothelium-independent action and that is dependent on the normalization of high blood pressure levels. The antihypertensive and vasorelaxant effects of NOX-1 are mainly endothelial-independent and it can be used to treat hypertension, a state associated with endothelial dysfunction.     

A randomized cross-over study of the effects of macronutrient composition and meal frequency on GLP-1, ghrelin and energy expenditure in humans

ObjectiveLittle is known about human postprandial increase of energy expenditure and satiety-associated hormones in relation to both meal frequency and macronutrient composition.DesignRandomized cross-over study with four conditions for each participant.MethodsSeven men and seven women (mean age 23 ± 1.5 years) were randomly assigned to the order of intake of a 750 kcal drink with the same protein content while having either 20 energy-percent (E%) or 55 E% from carbohydrates and the remaining energy from fat. Participants were also randomized to consume the drinks as one large beverage or as five 150 kcal portions every 30 min, starting in the fasting state in the morning. Energy expenditure (EE) was determined every 30 min by indirect calorimetry. Hormonal responses and suppression of hunger (by visual-analogue scales) were also studied. A p < 0.013 was considered statistically significant following Bonferroni-correction.ResultsThe area under the curve (AUC) for EE was higher during the 2.5 h after the high-carbohydrate drinks (p = 0.005 by Wilcoxon) and also after ingesting one drink compared with five (p = 0.004). AUC for serum active GLP-1 was higher after single drinks compared with five beverages (p = 0.002). Although GLP-1 levels remained particularly high at the end of the test during the low-carbohydrate meals, the AUC did not differ compared with the high-carbohydrate occasions (low-carbohydrate: 58.9 ± 18 pg/ml/h, high-carbohydrate: 45.2 ± 16 pg/ml/h, p = 0.028). Hunger sensations were suppressed more after single beverages compared with five small drinks (p = 0.009).ConclusionsWe found higher EE during 2.5 h following one large drink compared with five smaller beverages. Since hunger was also suppressed more efficiently, and serum GLP-1 levels were higher after one compared with five smaller drinks, our findings do not support nibbling to avoid hunger or to keep up EE from morning to noon.