Exploring inter-organ crosstalk to uncover mechanisms that regulate ß-cell function and mass.

Impaired ß-cell function and insufficient ß-cell mass compensation are twin pathogenic features that underlie type 2 diabetes (T2D). Current therapeutic strategies continue to evolve to improve treatment outcomes in different ethnic populations and include approaches to counter insulin resistance and improve ß-cell function. Although the effects of insulin secretion on metabolic organs such as liver, skeletal muscle and adipose is directly relevant for improving glucose uptake and reduce hyperglycemia, the ability of pancreatic ß-cells to crosstalk with multiple non-metabolic tissues is providing novel insights into potential opportunities for improving ß-cell function and/or mass that could have beneficial effects in patients with diabetes. For example, the role of the gastrointestinal system in the regulation of ß-cell biology is well recognized and has been exploited clinically to develop incretin-related antidiabetic agents. The microbiome and the immune system are emerging as important players in regulating ß-cell function and mass. The rich innervation of islet cells indicates it is a prime organ for regulation by the nervous system. In this review, we discuss the potential implications of signals from these organ systems as well as those from bone, placenta, kidney, thyroid, endothelial cells, reproductive organs and adrenal and pituitary glands that can directly impact ß-cell biology. An added layer of complexity is the limited data regarding the relative relevance of one or more of these systems in different ethnic populations. It is evident that better understanding of this paradigm would provide clues to enhance ß-cell function and/or mass in vivo in the long-term goal of treating or curing patients with diabetes.

Novel factors modulating human ß-cell proliferation.

ß-Cell dysfunction in type 1 and type 2 diabetes is accompanied by a progressive loss of ß-cells, and an understanding of the cellular mechanism(s) that regulate ß-cell mass will enable approaches to enhance hormone secretion. It is becoming increasingly recognized that enhancement of human ß-cell proliferation is one potential approach to restore ß-cell mass to prevent and/or cure type 1 and type 2 diabetes. While several reports describe the factor(s) that enhance ß-cell replication in animal models or cell lines, promoting effective human ß-cell proliferation continues to be a challenge in the field. In this review, we discuss recent studies reporting successful human ß-cell proliferation including WS6, an IkB kinase and EBP1 inhibitor; harmine and 5-IT, both DYRK1A inhibitors; GNF7156 and GNF4877, GSK-3ß and DYRK1A inhibitors; osteoprotegrin and Denosmab, receptor activator of NF-kB (RANK) inhibitors; and SerpinB1, a protease inhibitor. These studies provide important examples of proteins and pathways that may prove useful for designing therapeutic strategies to counter the different forms of human diabetes.

Metformin prevents liver tumorigenesis induced by high-fat diet in C57Bl/6 mice.

The prevalence of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is increasing with the growing epidemics of obesity and diabetes. NAFLD encompasses a clinicopathologic spectrum of disease ranging from isolated hepatic steatosis to NASH, which is a more aggressive form of fatty liver disease, to cirrhosis and, finally, hepatocellular carcinoma (HCC). The exact mechanism behind the development of HCC in NASH remains unclear; however, it has been established that hepatic steatosis is the important risk factor in the development of HCC. Metformin has recently drawn attention because of its potential antitumor effect. Here, we investigated the effects of metformin on high-fat diet (HFD)-induced liver tumorigenesis, using a mouse model of NASH and liver tumor. Metformin prevented long-term HFD-induced liver tumorigenesis in C57Bl/6 mice. Of note, metformin failed to protect against liver tumorigenesis in mice that had already begun to develop NAFLD. Metformin improved short-term HFD-induced fat accumulation in the liver, associated with the suppression of adipose tissue inflammation. Collectively, these results suggest that metformin may prevent liver tumorigenesis via suppression of liver fat accumulation in the early stage, before the onset of NAFLD, which seems to be associated with a delay in the development of inflammation of the adipose tissue.

Effect of highly lipolyzed goat cheese on HL-60 human leukemia cells: antiproliferative activity and induction of apoptotic DNA damage.

To establish cheese as a dairy product with health benefits, we embarked on examining the multifunctional role of cheeses, especially in the field of cancer prevention. The current study was designed to investigate whether different types of commercial goat cheeses may possess antiproliferative activity, using an HL-60 human promyelocytic leukemia cell line as a cancer cell model. Among 11 cheese extracts tested at 500µg/mL, 6 (Crottin de Chavignol, Pouligny Saint-Pierre, Chabichou du Poitou, Valencay, Kavli, and Sainte-Maure de Touraine) resulted in a significant decrease of cell viability, which is consistent with a decrease in viable cell number. Compared with the half-maximal inhibitory concentration (IC(50)) value of individual cheeses in cellular proliferation assays, the Pouligny Saint-Pierre extract showed strong inhibition. Incubation of cells in the presence of Pouligny Saint-Pierre extract resulted in induction of cellular morphological changes and apoptotic DNA fragmentation as well as expression of the active form of caspase-3 protein. Based on the quantification of the ratio of free fatty acids to triglycerides in different cheese samples, a significant correlation was detected between lipolytic ripeness and IC(50) values for antiproliferative capacity tested in HL-60 cells. Collectively, these results support a potential role of highly lipolyzed goat cheeses in the prevention of leukemic cell proliferation.

Control of beta cell function and proliferation in mice stimulated by small-molecule glucokinase activator under various conditions.

AIMS/HYPOTHESIS: We investigated changes in the expression of genes involved in beta cell function and proliferation in mouse islets stimulated with glucokinase activator (GKA) in order to elucidate the mechanisms by which GKA stimulates beta cell function and proliferation. METHODS: Islets isolated from mice were used to investigate changes in the expression of genes related to beta cell function and proliferation stimulated by GKA. In addition, Irs2 knockout (Irs2 (-/-)) mice on a high-fat diet or a high-fat diet containing GKA were used to investigate the effects of GKA on beta cell proliferation in vivo. RESULTS: In wild-type mice, Irs2 and Pdx1 expression was increased by GKA. In Irs2 (-/-) mice, GKA administration increased the glucose-stimulated secretion of insulin and Pdx1 expression, but not beta cell proliferation. It was particularly noteworthy that oxidative stress inhibited the upregulation of the Irs2 and Pdx1 genes induced by GKA. Moreover, whereas neither GKA alone nor exendin-4 alone upregulated the expression of Irs2 and Pdx1 in the islets of db/db mice, prior administration of exendin-4 to the mice caused GKA to increase the expression of these genes. CONCLUSIONS/INTERPRETATION: GKA-stimulated IRS2 production affected beta cell proliferation but not beta cell function. Oxidative stress diminished the effects of GKA on the changes in expression of genes involved in beta cell function and proliferation. A combination of GKA and an incretin-related agent might therefore be effective in therapy.

Effects of sevoflurane and enflurane on lower esophageal sphincter pressure and gastroesophageal pressure gradient in children.

PURPOSE: The effects of sevoflurane and enflurane on the intraluminal pressure of the lower esophagus (LE), lower esophageal sphincter (LES), and stomach were investigated in paralyzed and mechanically ventilated children under general anesthesia. METHODS: A total of 14 children, ASA physical status class I without risk factors for regurgitation, scheduled for orthopedic surgery were studied. After induction of anesthesia, we inserted a gastrointestinal pressure sensor nasally and monitored the intraluminal pressure of the LE, LES, and stomach under various concentrations of sevoflurane or enflurane with 66% nitrous oxide in oxygen prior to surgical incision. The barrier pressure (BrP), which is the difference between LES pressure and intragastric pressure, was calculated. RESULTS: Sevoflurane at 2.0 and 2.5 minimum alveolar concentration (MAC) decreased LES pressure, and enflurane at 2.0 and 2.5 MAC decreased both LES pressure and BrP in anesthetized children. The intraluminal pressure of the LE and stomach were not altered in either group. CONCLUSION: Sevoflurane and enflurane have an inhibitory effect on LES smooth muscle in anesthetized children. However, since the reduction was relatively low, even at high concentrations, these inhalation anesthetics are unlikely to influence gastroesophageal reflux during anesthesia.

[A case of reflex sympathetic dystrophy following a retinous surgery].

We present a case of a 54-year-old female with post-operative severe continuous ocular pain which occurred 3 months after retinal operation. Her general and mental conditions were good. We diagnosed it reflex sympathetic dystrophy and treated with stellate ganglion blocks (SGB) and continuous cervical epidural blocks. SGB and continuous cervical epidural blocks were effective. With increasing numbers of retinal surgery in recent years, more patients will suffer from postoperative ocular pain. We conclude that SGB or epidural block is useful for the therapy of ocular pain which can not be controlled by drugs and other therapy.

The relaxing effect of ketamine on isolated rabbit lower esophageal sphincter.

We used ketamine to investigate the effects and intracellular mechanisms of several anesthetics on strips of lower esophageal sphincter (LES) from rabbits. Ketamine induced dose-dependent relaxation of LES preparations. It increased the content of 3',5'-cyclic adenosine monophosphate (cAMP) dose-dependently, but decreased that of 3',5'-cyclic guanosine monophosphate (cGMP). Pretreatment with nicotinic acid, an inhibitor of adenylate cyclase, along with atropine to block neurogenic effects, antagonized ketamine-induced relaxation. Pretreatment with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H-89), a selective antagonist for cAMP-dependent protein kinase, similarly antagonized the relaxant effect of ketamine. Cholera toxin and dibutyryl cAMP induced LES relaxation. However, dibutyryl cGMP induced little LES relaxation, and pretreatment with NG-nitro-L-arginine or methylene blue did not alter the relaxant effect. Atropine, propranolol, phentolamine, vasoactive intestinal peptide (VIP) antagonist, and tetrodotoxin did not affect the ketamine-induced relaxation. This response, however, was potentiated in the presence of indomethacin or diphenhydramine. Ketamine-induced relaxation was inhibited in the presence of verapamil. These findings suggest that ketamine induces relaxation of LES, in part, by modulating the activity of adenylate cyclase and in part by inhibiting transmembrane influx of Ca2+.

Effects of various peptides on isolated rabbit lower esophageal sphincter.

Strips of lower esophageal sphincter (LES) from rabbits were tested for their responses to several peptides, and to electrical field stimulation (EFS) under the presence of some peptides. Substance P (SP), motilin, and bombesin induced contraction, and vasoactive intestinal peptide (VIP) induced relaxation. SP- and bombesin-induced contractions were antagonized by SP antagonist. VIP-induced relaxation was antagonized by phentolamine and VIP antagonist. Pretreatment with atropine, phentolamine, and diphenhydramine antagonized the motilin- and bombesin-induced contraction. Pretreatment with tetrodotoxin (TTX) attenuated the motilin- and bombesin-induced contraction, but not the SP-induced contraction and VIP-induced relaxation. EFS induced contraction, which was attenuated by TTX. Calcitonin gene-related peptide and neuropeptide Y had no effect on LES; however, they attenuated EFS-induced contraction. These findings suggest some characteristic peptidergic involvement in rabbit LES smooth muscle.

Anatomically corrected malposition (ACM) with subpulmonary infundibulum in a calf: clinico-morphologic case report.

A Japanese black calf with cyanosis, tachycardia, tachypnea and systolic murmur died of hypoxemia and cardiac insufficiency on the 38th day after birth. We could not establish the diagnosis during it's life. However, anatomically corrected malposition (ACM) with ventricular septal defect was confirmed at autopsy. There was situs solitus of the viscera and atria with atrio-ventricular discordance and ventriculo-arterial concordance. The ventricles demonstrated l-loop, i.e. on the right-sided ventricle there was a markedly enlarged morphologic left ventricle, and on the left-sided ventricle there was a hypoplastic morphologic right ventricle with a stenotic tricuspid valve and Ebstein-like deformity. The right posterior aorta originated from the left ventricle. The pulmonary artery arose from the left-sided right ventricle via infundibulum. There was a fibrous continuity between the aortic and mitral valve. We considered that this is the first reported case of bovine ACM.

[Combined therapy with prostaglandin E1 ointment and lumbar sympathetic ganglion block on intractable skin ulcers accompanied by Bürger's disease].

For the 2 patients with intractable skin ulcers and pain accompanied by thromboangiitis obliterans (Bürger's disease), we applied combined therapy with lumbar sympathetic block, continuous epidural block and prostaglandin E1 ointment. Prostaglandin E1 (PGE1) was prepared as a topical ointment by mixing with Plastibase (polyethylene resin, 5%, liquid paraffin, 95%) at a concentration of 10 micrograms.g-1. The ointment was kept in a refrigerator until use. Following debridement and washing of the surface of ulcers as required, the ointment was applied evenly onto the surrounding and over the surface of each ulcer 2 times daily after sterilization. With this therapy the ulcers were cured completely in 10 days after the start of treatment. No side effect was observed both locally and systemically. Although the combined therapy we used with prostaglandin E1 ointment was a noninvasive method, a remarkable shortening of the period of treatment was achieved.

Cisapride stimulates motility of the intestine via the 5-hydroxytryptamine receptors.

The effects of cisapride on intestinal contractility and on release of acetylcholine (ACh) were examined using the longitudinal muscle with the myenteric plexus preparation from the guinea pig ileum, as related to the 5-hydoxytryptamine (5-HT) receptor. 5-HT exerted a dual effect, transient increase in ACh release (EC50 = 2 X 10(-6)M) via the 5-HT3 receptor, followed by inhibition (EC50 = 5 X 10(-9)M) via the 5-HT1 receptor. Cisapride at low concentrations (10(-9)M to 10(-8)M) enhanced electrical stimulation -evoked contraction and ACh release. The effect of cisapride was mimicked by methysergide and was not altered by ICS 205-930. Cisapride antagonized the 5-HT (5 X 10(-9) M)-induced inhibitory effect and the IC50 of cisapride was 1.5 X 10(-9) M. These findings indicate that enhancement by low concentrations of cisapride may be due to a block of the inhibitory 5-HT1 receptor. Cisapride at medium concentrations (10(-8) M to 3 X 10(-7) M) induced enhancement of electrical stimulation-evoked twitch contractions and ACh release evoked by electrical stimulation which were antagonized by 10(-6) M ICS 205-930, while this compound antagonized the 5-HT (2 X 10(-6) M)-and 2-methyl-5-HT-induced excitatory effects, and the IC50 of cisapride was 5.2 X 10(-8) M. Thus, cisapride acts on the putative 5-HT4 receptor as an agonist and the 5-HT3 receptor as an antagonist. Cisapride at high concentrations (10(-6) M to 10(-5) M) evoked contraction and the release of ACh, and these effects were antagonized by ICS 205-930 (10(-6) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory effect of barbiturates and local anaesthetics on protein kinase C activation.

A calcium- and phospholipid-dependent protein kinase C subspecies purified from rat brain was inhibited by thiamylal, thiopentone, pentobarbitone, mepivacaine and bupivacaine. This was attributed to the inhibition of the activation process rather than to direct interaction with the active site of the enzyme. It is well established that unsaturated diacylglycerol markedly increases the affinity of protein kinase C for calcium ions. Kinetic analysis suggested that pentobarbitone brought about the inhibition by competing with the diacylglycerol diolein and that mepivacaine and bupivacaine competed with the phospholipid phosphatidylserine used in the assay. The possibility exists that the effects of local anaesthetics on the function of various tissues are due, in part, to an inhibitory action on protein kinase C.

Regulation of the substance P-induced contraction via the release of acetylcholine and gamma-aminobutyric acid in the guinea-pig urinary bladder.

1. The action of substance P (SP) on the release of gamma-aminobutyric acid (GABA) and acetylcholine (ACh) and on contraction were studied in strips of the guinea-pig urinary bladder. Substance P induced a dose-dependent contraction of strips of guinea-pig urinary bladder (EC50 = 1.2 x 10(-9) M). This contraction was not altered by tetrodotoxin, but with a dose of 10(-9) M and less, there was a complete inhibition by 10(-6) M) atropine. Contractions initiated by 3 x 10(-9) M) SP or more were partly inhibited by atropine. The EC50 value of substance P in the presence of atropine was 7.0 x 10(-9) M. 2. Substance P induced a Ca2+-dependent and tetrodotoxin-resistant release of [3H]-acetylcholine (ACh) from strips of urinary bladder preloaded with [3H]-choline (EC50 = 4.9 x 10(-10) M), and this release was antagonized by [D-Pro2,D-Trp7,9] substance P. 3. Bicuculline increased the substance P-induced contraction and the release of [3H]-ACh from the strips. 4. Substance P induced a Ca2+-dependent and tetrodotoxin-sensitive release of [3H]-gamma-aminobutyric acid (GABA) from strips preloaded with [3H]-GABA (EC50 = 2.6 x 10(-9) M), and this release was antagonized by [D-Pro2,D-Trp7,9] substance P. 5. Therefore, substance P appears to exert excitatory effects on the contractility of urinary bladder predominantly by stimulating its own receptor located on the cholinergic nerve terminals. GABA released by substance P inhibits stimulation of the cholinergic neurone. However, the direct action of substance P on the cholinergic neurone is more potent that the indirect action via GABA release.

Dual effects of 5-hydroxytryptamine on the release of gamma-aminobutyric acid from myenteric neurones of the guinea-pig ileum.

The effects of 5-hydroxytryptamine (5-HT) on the release of gamma-aminobutyric acid (GABA) were examined in the longitudinal muscle-myenteric plexus (LM-MP) preparation of guinea-pig ileum. 5-HT increased the spontaneous release and inhibited the electrically-evoked release of [3H]-GABA. The 5-HT-evoked release was Ca2+-dependent and tetrodotoxin-sensitive, and was antagonized by (3 alpha-tropanyl)-1H-indole-3-carboxylic acid ester (ICS 205-930), but not by methysergide and ketanserin. The inhibitory effect of 5-HT was antagonized by methysergide, but not by ketanserin and ICS 205-930. 8-Hydroxy-2-(di-n-propylamino)tetralin mimicked the inhibitory effect of 5-HT. Thus, 5-HT may exert an excitatory effect on the enteric GABAergic neurone via the 5-HT3 receptor and an inhibitory effect via the 5-HT1A receptor.