Gastric capacity, test meal intake, and appetitive hormones in binge eating disorder

Binge eating disorder (BED), characterized by ingestion of very large meals without purging afterwards, is found in a subset of obese individuals. We showed previously that stomach capacity is greater in obese than in lean subjects, and in this study, we investigated capacity in obese individuals with BED. We also determined ad-libitum intake of a test meal until extremely full. Furthermore, we measured various appetitive hormones (insulin, leptin, glucagon, CCK, ghrelin) and glucose before a fixed meal and for 120 min afterwards. An acetaminophen tracer was used to assess gastric emptying rate. We compared three groups of overweight women: 11 BED, 13 BE (subthreshold BED), and 13 non-binge-eating normals. The BED individuals had the largest stomach capacity as assessed by either maximum volume tolerated (P=.05) or by gastric compliance to pressure (P=.02) using an intragastric balloon. Although test meal intake did not differ between groups, it correlated (P=.03) with gastric capacity. The BED group showed a tendency (P=.06) to have greater area under the curve (AUC) and had higher values at 5 and 60 min (P<.05) for insulin compared to normals. Moreover, the BED subjects had lower ghrelin baselines premeal, and lower AUC for ghrelin, which then declined less postmeal than for the normals (P<.05). None of the other blood values differed, including glucose, leptin glucagon, and CCK, as well as acetaminophen, reflecting gastric emptying. The lower ghrelin in BED, although contrary to what was expected, is consistent with lower ghrelin in obesity, and suggests down-regulation of ghrelin by overeating. The lack of differences in CCK is consistent with the lack of differences in gastric emptying rate, given that CCK is released when nutrients reach the intestine. The results show that BED subjects have a large gastric capacity as well as abnormalities in meal-related ghrelin and insulin patterns that may be factors in binge eating.     

A role for glucose and insulin preprandial profiles to differentiate meals and snacks

A physiological distinction between eating occasions may help account for contradictory findings on the role of eating frequency in energy homeostasis. We assessed this issue using a midafternoon eating occasion known in France as the goûter that often consists of snack foods. Among the 24 male subjects, 8 habitually consumed four meals per day, i.e., were usual goûter eaters (GE) and 16 habitually took 3 meals per day, i.e., usual non-goûter non-snack eaters (NGNSE). All subjects were time blinded from lunchtime and had to request subsequent meals. Blood was continuously withdrawn and collected with a change of tube every 10 min until dinner request. During the session, 8 of the non-goûter eaters (NGE) were offered a snack 210 min after lunch and were designated as non-goûter snack eaters (NGSE) if they ate. Results showed that the goûter was preceded by high hunger scores and a linear decline in plasma glucose (−9.0±3.0%, P<.05) and insulin concentrations (−22.9±6.0%, P<.05). These profiles were not observed before the snack. The dinner of GE was requested later and was smaller compared to NGNSE, whereas the snack altered neither time of request nor energy intake (EI) at dinner. Among blood variables, leptin at the onset of eating was the only factor that was predictive of both intermeal interval and EI. The glucose and insulin profiles indicate that snacks should not be considered as meals in studies on the role of eating frequency in energy homeostasis.     

Relation between extracellular [K+], membrane potential and contraction in rat soleus muscle: modulation by the Na+-K+ pump

An increased extracellular K⁺ concentration ([K⁺]₀) is thought to cause muscle fatigue. We studied the effects of increasing [K⁺]₀ from 4 mM to 8–14 mM on tetanic contractions in isolated bundles of fibres and whole soleus muscles from the rat. Whereas there was little depression of force at a [K⁺]₀ of 8–9 mM, a further small increase in [K⁺]₀ to 11–14 mM resulted in a large reduction of force. Tetanus depression at 11 mM [K⁺]_o was increased when using weaker stimulation pulses and decreased with stronger pulses. Whereas the tetanic force/resting membrane potential (E _M) relation showed only moderate force depression with depolarization from –74 to –62 mV, a large reduction of force occurred whenE _M fell to –53 mV. The implications of these relations to fatigue are discussed. Partial inhibition of the Na⁺-K⁺ pump with ouabain (10^–6 M) caused additional force loss at 11 mM [K⁺]₀. Salbutamol, insulin, or calcitonin gene-related peptide all stimulated the Na⁺-K⁺ pump in muscles exposed to 11 mM [K⁺ ₀] and induced an average 26–33% recovery of tetanic force. When using stimulation pulses of 0.1 ms, instead of the standard 1.0-ms pulses, force recovery with these agents was 41–44% which was significantly greater (P < 0.025). Only salbutamol caused any recovery ofE _M (1.3 mV). The observations suggest that the increased Na⁺ concentration difference across the sarcolemma, following Na⁺-K⁺ pump stimulation, has an important role in restoring excitability and force.     

Analysis of children with type 1 diabetes in Korea: high prevalence of specific anti-islet autoantibodies, immunogenetic similarities to Western populations with "unique" haplotypes, and lack of discrimination by aspartic acid at position 57 of DQB

This study analyzed the expression of anti-islet autoantibodies and HLA-DR and -DQ genotypes in Korean children with type 1 diabetes mellitus (T1DM). The positivity of the anti-ICA512, anti-GAD65, and anti-insulin autoantibodies in the newly onset T1DM patients (n = 15) was 66.7%, 86.7%, and 46.7%, respectively, and all of them had one or more of the autoantibodies. HLA analysis showed higher frequencies of HLA-DRB1*0301, *0405, *09012 and -DQB1*0201, *0401, *03032 alleles in T1DM patients compared to controls (P(c) < 0.05). Because HLA-DQB1*0401, *03032 alleles carry aspartic acid at position 57 of DQB, susceptibility to T1DM in Korean children was not related to the presence of aspartic acid at position 57 of DQB1 locus. We suggest this unique HLA-DR, -DQ allele distribution might be an important factor for the low incidence of T1DM in Korea, and the combined anti-islet autoantibody assays could be valuable screening markers for the early detection of T1DM in Korea.     

Celiac vagotomy attenuates the ingestive responses to epinephrine and hypertonic saline but not insulin, 2-deoxy-D-glucose, or polyethylene glycol

The ingestive responses of rats given celiac vagotomy (C), combined celiac and hepatic vagotomy (CH), or low total vagotomy (removal of all tissue from around the esophagus, stomach and duodenum; LT) were compared with sham operated controls (S) in a series of regulatory challenges. The vagotomized groups responded normally to 2-deoxy-D-glucose (2DG; 125, 250, 500 mg/kg, IP), insulin (4, 8, 12 U/kg, IP), and polyethylene glycol (10 ml/kg: 30% w/v, SC), but displayed attenuated responses to epinephrine (40, 80, 120 micrograms/kg, IP) and hypertonic saline (10 ml/kg: 0.25, 0.5, 1.0 M, IP). These results can be interpreted as evidence that the celiac vagus carries a major component of hepatic afferent innervation. Additionally, when considered with other findings they suggest that whereas the anorectic activity of epinephrine is mostly confined to the liver, 2DG hyperphagia involves stimulation of a wider population of peripheral metabolic receptors.     

Diet selection and metabolic fuels in three models of diabetes mellitus

Dietary self-selection and circulating metabolic fuels (glucose, free fatty acids, ketones) were examined in three forms of experimental diabetes mellitus in rats: pancreatectomy and streptozotocin treatment in adult and neonatal rats. Changes in diet selection resulting from insulin replacement also were examined. Differences were found in diet selection and circulating metabolic fuels between these types of diabetes. Mildly diabetic rats selected large amounts of fat while more severely diabetic rats primarily selected protein. Insulin treatment enhanced carbohydrate intake of diabetic rats and nearly normalized diet selection and circulating metabolic fuels. All diabetic groups exhibited severe glucose intolerance. These results support the observations of the beneficial effects of low-carbohydrate diets, question the generality of the use of high-fat diets, and suggest a more important role for high-protein diets in energy regulation in severely diabetic rats.     

Expansion of human nasal chondrocytes on macroporous microcarriers enhances redifferentiation

Articular cartilage has a limited capacity for self-repair. To overcome this problem, it is expected that functional cartilage replacements can be created from expanded chondrocytes seeded in biodegradable scaffolds. Expansion of chondrocytes in two-dimensional culture systems often results in dedifferentiation. This investigation focuses on the post-expansion phenotype of human nasal chondrocytes expanded on macroporous gelatin CultiSpher G microcarriers. Redifferentiation was evaluated in vitro via pellet cultures in three different culture media. Furthermore, the chondrogenic potential of expanded cells seeded in polyethylene glycol terephthalate/ polybuthylene terephthalate (PEGT/PBT) scaffolds, cultured for 14 days in vitro, and subsequently implanted subcutaneously in nude mice, was assessed.

Chondrocytes remained viable during microcarrier culture and yielded doubling times (1.07±0.14 days) comparable to T-flask expansion (1.20±0.36 days). Safranin-O staining from pellet culture in different media demonstrated that production of GAG per cell was enhanced by microcarrier expansion. Chondrocyte–polymer constructs with cells expanded on microcarriers contained significantly more proteoglycans after subcutaneous implantation (288.5±29.2 μg) than those with T-flask-expanded cells (164.0±28.7 μg). Total collagen content was similar between the two groups.

This study suggests that macroporous gelatin microcarriers are effective matrices for nasal chondrocyte expansion, while maintaining the ability of chondrocyte differentiation. Although the exact mechanism by which chondrocyte redifferentiation is induced through microcarrier expansion has not yet been elucidated, this technique shows promise for cartilage tissue engineering approaches.     

Effect of training on hormonal responses to exercise in competitive swimmers

Summary The effects of 9 weeks of training on responses of plasma hormones to swimming were studied in eight competitive swimmers who had not trained for several months. Two types of swimming tests were used: (1) 200 yd, a high intensity, exhausting type of exercise in which maximal effort was required both before and after training, and (2) 1000 yd, a pace type of exercise in which subjects swam as fast as possible prior to training and at the same rate after training. Plasma levels of glucagon increased and of insulin decreased during 1000 yd of swimming, but were not altered by 200 yd of swimming. No training effects were apparent in responses of plasma insulin and glucagon to these short-term, high intensity exercise tests. During the 1000 yd swim, plasma adrenaline was 0.8 ng/ml before vs. 0.1 ng/ml after training. Plasma noradrenaline response decreased from 3.4 to 1.2 ng/ml as a result of training. In the 200 yd swim, adrenaline, but not noradrenaline, was lower after training.R. C. Hickson and R. K. Conlee were postdoctoral research trainees supported by NIH Training Grant AM-05341.J. M. Hagberg was a postdoctoral research trainee supported by NIH Training Grant HL-07081.     

Dose-response relationship for a positive inotropic effect of insulin on isolated papillary muscle

Summary Beneficial effect of glucose and insulin on the myocardium are still a matter of discussion. The influence of insulin on isometric force of contraction of right ventricular papillary muscles of guinea pigs war studied. The papillary muscles were mounted vertically in a 95% O₂, 5% CO₂ modified Krebs-Hensuleit solution (31.5° C, 5.5 mM glucose) and stimulated 1/s. A positive inotropic effect of insulin was dedectable at a concentration of 5×10^–4 IU/ml insulin, was half maximal (52% above controle force of contraction) at 8×10^–3 IU/ml and maximal at 10^–1 IU/ml. The maximal positive inotropic effect was observed 4.7±0.6 min after addition of insulin. After the maximum there was a decrease to a steady state level of 109.8±8.5% of control (p<0.05) in 14.6±1.3 min. Higher glucose (16.5 mM) only shifted the half maximal positive inotropic effect to 5.5×10^–3 IU/ml insulin (n.s.). Inhibition of glycolysis with hypoxia or jodoacetate (5×10^–5 M) did not prevent the positive inotropic effect as known as 75% of control force was retained. When glucose transport was blocked with phlorizin (5×10^–3 M) or phloritin (5×10^–4 M) no positive inotropic action of insulin was observed. Therefore we conclude that the positive inotropic effect of insulin in isolated papillary muscles is mediated by inhanced glucose transport.     

Cell signalling-mediating insulin increase of mRNA expression for cationic amino acid transporters-1 and -2 and membrane hyperpolarization in human umbilical vein endothelial cells

Insulin induces vasodilatation in human subjects and increases l-arginine transport and NO synthesis in human umbilical vein endothelial cells (HUVEC). Cell signalling events associated with insulin effects on activity and mRNA expression of the human cationic amino acid transporters 1 (hCAT-1) and 2B (hCAT-2B) are unknown. l-Arginine transport and eNOS activity were determined in HUVEC exposed to insulin. mRNA levels for hCAT-1, hCAT-2B and eNOS were quantitated by real time RT-PCR and endothelial NO synthase (eNOS) protein was identified by Western blot analysis. Intracellular Ca²⁺, l-arginine and l-citrulline levels, l-[³H]citrulline formation from l-[³H]arginine, cGMP formation, nitrite level, ATP release and membrane potential were determined. Insulin increased l-arginine transport and the mRNA levels for hCAT-1 and hCAT-2B and eNOS expression and activity. Insulin also induced membrane hyperpolarization and increased intracellular Ca²⁺, l-[³H]citrulline, cGMP and nitrite formation. Insulin-mediated stimulation of the l-arginine/NO pathway is thus associated with increased hCAT-1 and hCAT-2B mRNA, and eNOS expression, via mechanisms involving membrane hyperpolarization, mitogen-activated protein kinases p42 and p44, phosphatidylinositol 3-kinase, NO and protein kinase C. We have characterized a cell signalling pathway by which hyperinsulinaemia could lead to vasodilatation in human subjects, and which could have implications in patients in whom plasma insulin levels are altered, such as in diabetes mellitus.