Search for Dark Photon Dark Matter in the Mass Range 74-110 µeV with a Cryogenic Millimeter-Wave Receiver.

We search for the dark photon dark matter (DPDM) using a cryogenic millimeter-wave receiver. DPDM has a kinetic coupling with electromagnetic fields with a coupling constant of χ and is converted into ordinary photons at the surface of a metal plate. We search for signal of this conversion in the frequency range 18-26.5 GHz, which corresponds to the mass range 74-110 µeV/c^{2}. We observed no significant signal excess, allowing us to set an upper bound of χ<(0.3-2.0)×10^{-10} at 95% confidence level. This is the most stringent constraint to date and tighter than cosmological constraints. Improvements from previous studies are obtained by employing a cryogenic optical path and a fast spectrometer.

Efficacy and Safety of Lixisenatide in Japanese Patients with Type 2 Diabetes Insufficiently Controlled with Basal Insulin±Sulfonylurea: A Subanalysis of the GetGoal-L-Asia Study.

The aim of the study was to evaluate the efficacy and safety of once-daily lixisenatide 20 µg as add-on to basal insulin with or without sulfonylurea in Asian patients with type 2 diabetes mellitus. The study as a subanalysis of the 159 Japanese patients from the 24-week double-blind GetGoal-L-Asia study (NCT00866658) who received once-daily lixisenatide or placebo. The primary endpoint was change from baseline in HbA1c evaluated using analysis of covariance. Once-daily lixisenatide significantly reduced mean HbA1c [least squares mean difference vs. placebo - 1.1% (- 12 mmol/mol); p<0.0001]. Significantly more patients in the lixisenatide group reached HbA1c targets of < 7% (53 mmol/mol; 31.4 vs. 2.3% for placebo; p<0.0001) and ≤ 6.5% (48 mmol/mol; 12.9 vs. 1.2% for placebo; p=0.0028). Lixisenatide significantly reduced 2-h postprandial plasma glucose (least squares mean difference vs. placebo-8.64 mmol/l; p<0.0001), glucose excursion (least squares mean difference vs. placebo - 7.80 mmol/l; p<0.0001) and fasting plasma glucose (least squares mean difference vs. placebo - 0.96 mmol/l; p=0.0126). Body weight was reduced with lixisenatide but with no significant difference vs. placebo. Gastrointestinal adverse events were more frequent with lixisenatide (61.1 vs. 11.5% for placebo) but were generally transient and mild-to-moderate in intensity. The incidence of symptomatic hypoglycemia was 39.0 vs. 13.5% in patients receiving sulfonylureas and 32.3 vs. 22.9% in those not receiving sulfonylureas, for lixisenatide and placebo, respectively. In Japanese patients with type 2 diabetes mellitus, once-daily lixisenatide was well tolerated and led to significant and clinically relevant improvement in glycemic control, with a pronounced effect on postprandial plasma glucose.

Use of the Japanese health insurance claims database to assess the risk of acute pancreatitis in patients with diabetes: comparison of DPP-4 inhibitors with other oral antidiabetic drugs.

This study was initiated to evaluate the association of acute pancreatitis (AP) with the use of dipeptidyl peptidase-4 (DPP-4) inhibitors among patients with diabetes in Japan. A retrospective cohort study of a large medical and pharmacy claims database was performed to compare the incidence of AP among those receiving DPP-4 inhibitors and those receiving other oral antidiabetic drugs. The incidence of all AP and hospitalizations for AP was similar between the two groups. Previous exposure to DPP-4 inhibitors did not affect occurrence of AP in patients on other oral antidiabetic drugs. The Kaplan-Meier curve for time to AP was similar between the two groups, and was not affected by previous exposure to DPP-4 inhibitors. The Cox proportional hazard models showed the incidence of AP was not significantly higher in those receiving DPP-4 inhibitors. Despite numerous, important limitations related to claims database-based analyses, our results indicate that there is no increased risk of AP with use of DPP-4 inhibitors among patients with diabetes in Japan.

Pharmacodynamics of the glucagon-like peptide-1 receptor agonist lixisenatide in Japanese and Caucasian patients with type 2 diabetes mellitus poorly controlled on sulphonylureas with/without metformin.

AIMS: The PDY6797 study evaluated efficacy, safety and pharmacodynamics of lixisenatide in Japanese and Caucasian patients with type 2 diabetes mellitus (T2DM) insufficiently controlled with sulphonylureas with/without metformin. METHODS: This randomized, double-blind, placebo-controlled trial comprised a single-dose assessment of lixisenatide 5 and 10 µg, and a 5- to 6-week repeated dose-escalation assessment of lixisenatide 5 to 30 µg once (QD) or twice daily (BID). The primary endpoint was change in postprandial plasma glucose (PPG) area under the curve (AUC)[0:29-4:30 h] after a standardized breakfast at the highest tolerated lixisenatide dose. Change from baseline in glycated haemoglobin (HbA1c), 2-h PPG and fasting plasma glucose (FPG) were assessed, as were adverse events. RESULTS: Change from baseline in PPG AUC[0:29-4:30 h] with lixisenatide QD and BID was significantly greater than placebo (p < 0.0001 for all study populations), with particularly prominent effects in Japanese patients. Greater reductions in PPG AUC[0:29-4:30 h] were seen with lixisenatide QD versus BID, while the totality of evidence suggested that the lixisenatide 20 µg dose was optimal. In the overall population, changes from baseline for 2-h PPG, HbA1c and FPG were significant with lixisenatide QD and BID versus placebo (p < 0.01 for all). Lixisenatide was well tolerated. CONCLUSIONS: Lixisenatide significantly reduced PPG AUC[0:29-4:30 h] versus placebo at the highest well-tolerated dose in patients with T2DM treated with sulphonylureas with/without metformin and had a good safety and tolerability profile. Japanese patients experienced particular benefits with lixisenatide in terms of reductions in PPG excursions.

Randomized, double-blind, placebo-controlled trial of the once-daily GLP-1 receptor agonist lixisenatide in Asian patients with type 2 diabetes insufficiently controlled on basal insulin with or without a sulfonylurea (GetGoal-L-Asia).

AIMS: To assess the efficacy and safety of once-daily lixisenatide versus placebo in Asian patients with type 2 diabetes insufficiently controlled on basal insulin ± sulfonylurea. METHODS: In this 24-week, randomized, double-blind, placebo-controlled, parallel-group, multicentre study, participants (mean baseline HbA(1c) 8.53%) from Japan, Republic of Korea, Taiwan and the Philippines received lixisenatide (n = 154) or placebo (n = 157) in a stepwise dose increase to 20 µg once daily. The primary endpoint was HbA(1c) change from baseline to week 24. RESULTS: Once-daily lixisenatide significantly improved HbA(1c) versus placebo (LS mean difference vs. placebo = -0.88% [95%CI= -1.116, -0.650]; p < 0.0001), and allowed more patients to achieve HbA(1c) <7.0% (35.6 vs. 5.2%) and ≤ 6.5% (17.8 vs. 1.3%). Lixisenatide also significantly improved 2-h postprandial plasma glucose and glucose excursion, average 7-point self-monitored blood glucose and fasting plasma glucose. Lixisenatide was well tolerated; 86% of patients on lixisenatide completed the study versus 92% on placebo. Ten (6.5%) lixisenatide and 9 (5.7%) placebo patients experienced serious adverse events. More lixisenatide patients [14 (9.1%)] discontinued for adverse events versus placebo [5 (3.2%)], mainly with gastrointestinal causes. Nausea and vomiting were reported in 39.6 and 18.2% of patients on lixisenatide versus 4.5 and 1.9% on placebo. Symptomatic hypoglycaemia was more frequent with lixisenatide (42.9%) versus placebo (23.6%), but was similar between groups (32.6 vs. 28.3%, respectively), in those not receiving sulfonylureas. No severe hypoglycaemia was reported. CONCLUSIONS: In an Asian type 2 diabetes population insufficiently controlled by basal insulin ± sulfonylurea, once-daily lixisenatide significantly improved glycaemic control, with a pronounced postprandial effect, and was well tolerated.

Efficacy and safety of alogliptin added to metformin in Japanese patients with type 2 diabetes: a randomized, double-blind, placebo-controlled trial with an open-label, long-term extension study.

AIMS: To evaluate the efficacy and safety of alogliptin added to metformin versus metformin monotherapy in Japanese patients with type 2 diabetes who achieved inadequate glycaemic control on metformin (500 or 750 mg/day) + diet/exercise. METHODS: In a randomized, double-blind trial, 288 patients with type 2 diabetes mellitus T2DM received either 12.5 or 25 mg alogliptin once daily + metformin or placebo + metformin for 12 weeks. Thereafter, 276 patients continued on one of the two alogliptin dosages + metformin in an open-label extension for 40 weeks. The primary efficacy endpoint in the randomized, double-blind phase was the change in HbA1c from baseline (week 0) to the end of treatment (week 12). The primary endpoint during the long-term extension phase was adverse events. RESULTS: After 12 weeks both dosages of alogliptin + metformin produced significantly greater changes from baseline in HbA1c than placebo (metformin monotherapy: with changes in LS means - 0.55 and - 0.64% vs. 0.22%, respectively; p < 0.0001). Incidences of adverse effects were comparable between groups, with no increases in hypoglycaemia. Over 52 weeks, there were no safety or tolerability concerns with alogliptin when added to metformin. CONCLUSIONS: Alogliptin 12.5 and 25 mg once daily was safe and effective when added to metformin (500 or 750 mg/day) in Japanese patients with inadequately controlled type 2 diabetes on metformin alone.

Efficacy and safety of alogliptin added to pioglitazone in Japanese patients with type 2 diabetes: a randomized, double-blind, placebo-controlled trial with an open-label long-term extension study.

AIM: To assess the efficacy and safety of alogliptin added to pioglitazone versus pioglitazone monotherapy, in Japanese patients with type 2 diabetes who achieved inadequate glycaemic control on pioglitazone plus diet/exercise. METHODS: Patients were stabilized on pioglitazone 15 or 30 mg/day plus diet/exercise during a 16-week screening period. Patients with HbA1c of 6.9-10.4% were randomized to 12 weeks' double-blind treatment with alogliptin 12.5 or 25 mg once daily or placebo, added to their stable pioglitazone regimen. The primary endpoint was the change in HbA1c from baseline to week 12. Patients had an option to continue in a 40-week, open-label extension study, with those originally randomized to alogliptin remaining on the same dosage regimen while patients treated with placebo were randomly allocated to alogliptin 12.5 or 25 mg (added to their stable pioglitazone). RESULTS: The change from baseline in HbA1c after 12 weeks was significantly greater with alogliptin 12.5 mg added to pioglitazone and alogliptin 25 mg added to pioglitazone than with placebo added to pioglitazone (-0.91 and -0.97% vs. -0.19%; p < 0.0001). Responder rates (HbA1c <6.9% and HbA1c <6.2%) and changes in fasting and postprandial blood glucose levels showed a similar positive trend in terms of glycaemic control. The benefits seen with alogliptin were sustained during the 40-week extension period. Alogliptin added to pioglitazone was generally well tolerated; hypoglycaemia was infrequent and increases in body weight were minor. CONCLUSIONS: Once-daily alogliptin was effective and generally well tolerated when given as add-on therapy to pioglitazone in Japanese patients with type 2 diabetes who achieved inadequate glycaemic control on pioglitazone plus lifestyle measures. Clinical benefits were maintained for 52 weeks.

The effect of laryngeal elevation training on swallowing function in patients with dysphagia.

OBJECTIVE: To investigate the effect of laryngeal elevation training without highly loaded head lifting on swallowing function in patients with dysphagia. METHODS: Fifty-seven patients with dysphagia (36 men; mean age, 78.5 ± 11.4 years) were included. All participants performed the swallowing forehead exercise and the chin push-pull manoeuvre for two months. Videoendoscopy to assess swallowing function, the peak expiratory flow test and the hand grip strength test were performed at the initial visit (time 1) and two months after the start of the intervention (time 2). We used the Hyodo score, a scoring method for videoendoscopic assessment, for evaluation of swallowing function. RESULTS: The linear mixed model showed a significant main effect of time (the Hyodo score at time 1 was greater than the score at time 2). The effects of the co-variates were not significant. CONCLUSION: The present study demonstrated the significant effect of laryngeal elevation training without head lifting on the Hyodo score.

Metformin suppresses hepatic gluconeogenesis and lowers fasting blood glucose levels through reactive nitrogen species in mice.

AIMS/HYPOTHESIS: Metformin, the major target of which is liver, is commonly used to treat type 2 diabetes. Although metformin activates AMP-activated protein kinase (AMPK) in hepatocytes, the mechanism of activation is still not well known. To investigate AMPK activation by metformin in liver, we examined the role of reactive nitrogen species (RNS) in suppression of hepatic gluconeogenesis. METHODS: To determine RNS, we performed fluorescence examination and immunocytochemical staining in mouse hepatocytes. Since metformin is a mild mitochondrial complex I inhibitor, we compared its effects on suppression of gluconeogenesis, AMPK activation and generation of the RNS peroxynitrite (ONOO(-)) with those of rotenone, a representative complex I inhibitor. To determine whether endogenous nitric oxide production is required for ONOO(-) generation and metformin action, we used mice lacking endothelial nitric oxide synthase (eNOS). RESULTS: Metformin and rotenone significantly decreased gluconeogenesis and increased phosphorylation of AMPK in wild-type mouse hepatocytes. However, unlike rotenone, metformin did not increase the AMP/ATP ratio. It did, however, increase ONOO(-) generation, whereas rotenone did not. Exposure of eNOS-deficient hepatocytes to metformin did not suppress gluconeogenesis, activate AMPK or increase ONOO(-) generation. Furthermore, metformin lowered fasting blood glucose levels in wild-type diabetic mice, but not in eNOS-deficient diabetic mice. CONCLUSIONS/INTERPRETATION: Activation of AMPK by metformin is dependent on ONOO(-). For metformin action in liver, intra-hepatocellular eNOS is required.

Bone marrow transplantation as a strategy for treatment of non-insulin-dependent diabetes mellitus in KK-Ay mice.

The effects of allogeneic bone marrow transplantation (BMT) on non-insulin-dependent diabetes mellitus (NIDDM) were examined using KK-Ay mice. KK-Ay mice reconstituted with KK-Ay bone marrow cells showed glycosuria, hyperinsulinemia, and hyperlipidemia. However, KK-Ay mice (H-2b) that had been lethally irradiated (9.0 Gy) and then reconstituted with T cell-depleted bone marrow cells from normal BALB/c mice (H-2d) showed negative urine sugar with decreases in serum insulin and lipid levels 4 mo after BMT. Morphological recovery of islets and glomeruli was also noted after allogeneic BMT. These findings suggest that BMT can be used to treat not only a certain type of NIDDM but also its complications such as hyperlipidemia and diabetic nephropathy.

Exendin-4 protects pancreatic beta cells from the cytotoxic effect of rapamycin by inhibiting JNK and p38 phosphorylation.

It has been reported that the immunosuppressant rapamycin decreases the viability of pancreatic beta cells. In contrast, exendin-4, an analogue of glucagon-like peptide-1, has been found to inhibit beta cell death and to increase beta cell mass. We investigated the effects of exendin-4 on the cytotoxic effect of rapamycin in beta cells. Incubation with 10 nM rapamycin induced cell death in 12 h in murine beta cell line MIN6 cells and Wistar rat islets, but not when coincubated with 10 nM exendin-4. Rapamycin was found to increase phosphorylation of c-Jun amino-terminal kinase (JNK) and p38 in 30 minutes in MIN6 cells and Wistar rat islets while exendin-4 decreased their phosphorylation. Akt and extracellular signal-regulated kinase (ERK) were not involved in the cytoprotective effect of exendin-4. These results indicate that exendin-4 may exert its protective effect against rapamycin-induced cell death in pancreatic beta cells by inhibiting JNK and p38 signaling.

Improved glycaemic control with minimal hypoglycaemia and no weight change with the once-daily human glucagon-like peptide-1 analogue liraglutide as add-on to sulphonylurea in Japanese patients with type 2 diabetes.

AIM: Sulphonylureas (SUs) are often used as first-line treatments for type 2 diabetes in Japan, hence it is important to study new antidiabetic drugs in combination with SUs in Japanese patients. METHODS: The efficacy and safety of the once-daily human glucagon-like peptide-1 (GLP-1) analogue liraglutide were compared in 264 Japanese subjects [mean body mass index (BMI) 24.9 kg/m(2); mean glycated haemoglobin (HBA1c) 8.4%] randomized and exposed to receive liraglutide 0.6 mg/day (n = 88), 0.9 mg/day (n = 88) or placebo (n = 88) each added to SU monotherapy (glibenclamide, glicazide or glimeprimide) in a 24-week, double-blind, parallel-group trial. RESULTS: The mean change in HBA1c from baseline to week 24 (LOCF) was -1.56 (s.d. 0.84) and -1.46 (s.d. 0.95) with liraglutide 0.9 and 0.6 mg respectively, and -0.40 (s.d. 0.93) with placebo. HBA1c decreased in the placebo group from 8.45 to 8.06%, while liraglutide reduced HBA1c from 8.60 to 7.14%, and from 8.23 to 6.67% at the 0.6 and 0.9 mg doses respectively. Mean HBA1c at week 24 of the two liraglutide groups were significantly lower than the placebo group (p < 0.0001 for both). More subjects reached HBA1c < 7.0% with liraglutide (0.6 mg: 46.5%; 0.9 mg: 71.3%) vs. placebo (14.8%). Fasting plasma glucose (FPG) levels were significantly improved with liraglutide (difference -1.47 mmol/l and -1.80 mmol/l with 0.6 and 0.9 mg vs. placebo; p < 0.0001). Overall safety was similar between treatments: no major hypoglycaemic episodes were reported, while 84/77/38 minor hypoglycaemic episodes occurred in the 0.6 mg/0.9 mg and placebo treatment groups (all in combination with SU), reflecting lower ambient glucose levels. No relevant change in mean body weight occurred in subjects receiving liraglutide (0.6 mg: 0.06 kg; 0.9 mg: -0.37 kg), while mean body weight decreased in subjects receiving placebo (-1.12 kg). CONCLUSIONS: The addition of liraglutide to SU treatment for 24 weeks dose-dependently improved glycaemic control vs. SU monotherapy, without causing major hypoglycaemia or weight gain or loss.

Niflumic acid-sensitive ion channels play an important role in the induction of glucose-stimulated insulin secretion by cyclic AMP in mice.

AIMS/HYPOTHESIS: We have previously reported that glucose-stimulated insulin secretion (GSIS) is induced by glucagon-like peptide-1 (GLP-1) in mice lacking ATP-sensitive K(+) (K(ATP)) channels (Kir6.2(-/-) mice [up-to-date symbol for Kir6.2 gene is Kcnj11]), in which glucose alone does not trigger insulin secretion. This study aimed to clarify the mechanism involved in the induction of GSIS by GLP-1. METHODS: Pancreas perfusion experiments were performed using wild-type (Kir6.2(+/+)) or Kir6.2(-/-) mice. Glucose concentrations were either changed abruptly from 2.8 to 16.7 mmol/l or increased stepwise (1.4 mmol/l per step) from 2.8 to 12.5 mmol/l. Electrophysiological experiments were performed using pancreatic beta cells isolated from Kir6.2(-/-) mice or clonal pancreatic beta cells (MIN6 cells) after pharmacologically inhibiting their K(ATP) channels with glibenclamide. RESULTS: The combination of cyclic AMP plus 16.7 mmol/l glucose evoked insulin secretion in Kir6.2(-/-) pancreases where glucose alone was ineffective as a secretagogue. The secretion was blocked by the application of niflumic acid. In K(ATP) channel-inactivated MIN6 cells, niflumic acid similarly inhibited the membrane depolarisation caused by cAMP plus glucose. Surprisingly, stepwise increases of glucose concentration triggered insulin secretion only in the presence of cAMP or GLP-1 in Kir6.2(+/+), as in Kir6.2(-/-) pancreases. CONCLUSIONS/INTERPRETATION: Niflumic acid-sensitive ion channels participate in the induction of GSIS by cyclic AMP in Kir6.2(-/-) beta cells. Cyclic AMP thus not only acts as a potentiator of insulin secretion, but appears to be permissive for GSIS via novel, niflumic acid-sensitive ion channels. This mechanism may be physiologically important for triggering insulin secretion when the plasma glucose concentration increases gradually rather than abruptly.

A novel point mutation in the human insulin gene giving rise to hyperproinsulinemia (proinsulin Kyoto).

We have identified a 65-yr-old nonobese Japanese man with diabetes mellitus, fasting hyperinsulinemia (150-300 pM), and a reduced fasting C-peptide/insulin molar ratio of 2.5-3.0. Fasting hyperinsulinemia was also found in his son and daughter. Analysis of insulin isolated from the serum of the proband and his son by reverse-phase high performance liquid chromatography revealed a minor peak coeluting with human insulin and a major peak of proinsulin-like materials. The insulin gene of the patient was amplified by the polymerase chain reaction and the products were sequenced. A novel point mutation was identified in which guanine was replaced by thymine. The substitution gives rise to a new HindIII recognition site and results in the amino acid replacement of leucine for arginine at position 65. These results indicate that the amino-acid replacement prevents recognition of the C-peptide-A chain dibasic protease and results in an elevation of proinsulin-like materials in the circulation. Furthermore, in this family the proinsulin-like materials is due to a biosynthetic defect, inherited as an autosomal dominant trait. Rapid detection of this mutation can be accomplished by HindIII restriction enzyme mapping of polymerase chain reaction-generated DNA, which enables us to facilitate the diagnosis and screening.

Decreased 1,25-dihydroxyvitamin D3 receptor density is associated with a more severe form of parathyroid hyperplasia in chronic uremic patients.

The resistance of parathyroid cells to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in uremic hyperparathyroidism is thought to be caused, in part, by a 1,25(OH)2D3 receptor (VDR) deficiency in the parathyroids. However, results of biochemical studies addressing VDR numbers in the parathyroids are controversial. Several studies have found VDR content to be decreased in the parathyroids of uremic patients and animals, while others have found no such decrease in the parathyroids of uremic animals. To clarify the role of VDR, we investigated VDR distribution in surgically-excised parathyroids obtained from chronic dialysis patients by immunohistochemistry. We classified the parathyroids as exhibiting nodular or diffuse hyperplasia. Our studies demonstrated a lower density of VDR in the parathyroids showing nodular hyperplasia than in those showing diffuse hyperplasia. Even in the parathyroids showing diffuse hyperplasia, nodule-forming areas were present; these areas were virtually negative for VDR staining. A significant negative correlation was found between VDR density and the weight of the parathyroids. These findings indicate that the conflicting results of biochemical studies may be caused by the heterogeneous distribution of VDR; the decreased VDR density in parathyroids may contribute to the progression of secondary hyperparathyroidism and to the proliferation of parathyroid cells that is seen in uremia.

Vagal regulation of insulin, glucagon, and somatostatin secretion in vitro in the rat.

Using a new in vitro procedure of the isolated perfused rat pancreas with vagal innervation, electrical vagal stimulation produced an increase in both insulin and glucagon secretion in proportion to the pulse frequency, but an inhibition in somatostatin release. When atropine was infused, both insulin and glucagon responses to vagal stimulation were partially suppressed, whereas somatostatin release was enhanced. In the presence of hexamethonium, vagal stimulation failed to affect insulin, glucagon, or somatostatin secretion. Propranolol partially blocked both insulin and glucagon responses but did not influence somatostatin response. Phentolamine had no significant effect on release of hormones. Simultaneous administration of propranolol and phentolamine tended to inhibit both insulin and glucagon responses to vagal stimulation. These findings suggest that not only a cholinergic but also a noncholinergic neuron may be involved in vagal regulation of pancreatic hormone secretion and that these neurons may be under the control of preganglionic vagal fibers via nicotinic receptors.

Identification of somatostatin receptor subtypes and an implication for the efficacy of somatostatin analogue SMS 201-995 in treatment of human endocrine tumors.

The presence of somatostatin receptors has been demonstrated in various endocrine tumors as well as in normal tissues. We recently have cloned five human somatostatin receptor subtypes (SSTR1-SSTR5). These mRNAs are expressed in a tissue-specific manner. In this study, we have determined the somatostatin receptor subtypes expressed in various endocrine tumors using a reverse transcriptase polymerase chain reaction method. In two cases of glucagonoma and its metastatic lymph nodes in one case, all the SSTR subtype mRNAs except SSTR5 mRNA were expressed. In four cases of insulinoma, SSTR1 and SSTR4 mRNAs were detected, but SSTR2 mRNA was not detected in one case and SSTR3 mRNA was not detected in two cases, indicating a heterogeneous expression of SSTR subtypes in insulinomas. Interestingly, SSTR3 mRNA, which is highly expressed in rat pancreatic islets, is not expressed in normal human pancreatic islets, while SSTR1, SSTR2, and SSTR4 mRNAs are expressed. In three cases of pheochromocytoma, SSTR1 and SSTR2 mRNAs were detected, showing an expression pattern identical to that of normal adrenal gland. In a carcinoid, SSTR1 and SSTR4 mRNAs were detected. We have also found that human SSTR2 shows a high affinity for SMS 201-995, which has been used clinically for the treatment of endocrine tumors. Since SMS 201-995 was effective in the treatment of a patient with glucagonoma in which SSTR2 mRNA was present, but had no effect in a patient with carcinoid in which SSTR2 mRNA was not detected, this study suggests that the efficacy of SMS 201-995 may depend, at least in part, on the expression of SSTR2 in tumors.

Alterations in basal and glucose-stimulated voltage-dependent Ca2+ channel activities in pancreatic beta cells of non-insulin-dependent diabetes mellitus GK rats.

In genetically occurring non-insulin-dependent diabetes mellitus (NIDDM) model rats (GK rats), the activities of L- and T-type Ca2+ channels in pancreatic beta cells are found to be augmented, by measuring the Ba2+ currents via these channels using whole-cell patch-clamp technique, while the patterns of the current-voltage curves are indistinguishable. The hyper-responsiveness of insulin secretion to nonglucose depolarizing stimuli observed in NIDDM beta cells could be the result, therefore, of increased voltage-dependent Ca2+ channel activity. Perforated patch-clamp recordings reveal that the augmentation of L-type Ca2+ channel activity by glucose is markedly less pronounced in GK beta cells than in control beta cells, while glucose-induced augmentation of T-type Ca2+ channel activity is observed neither in the control nor in the GK beta cells. This lack of glucose-induced augmentation of L-type Ca2+ channel activity in GK beta cells might be causatively related to the selective impairment of glucose-induced insulin secretion in NIDDM beta cells, in conjunction with an insufficient plasma membrane depolarization due to impaired closure of the ATP-sensitive K+ channels caused by the disturbed intracellular glucose metabolism in NIDDM beta cells.

Regulation of Na,K-adenosine triphosphatase gene expression by sodium ions in cultured neonatal rat cardiocytes.

Na,K-ATPase (Na,K-pump) plays an important role in the regulation of intracellular ion composition. The purpose of this study is to determine whether Na+ regulates the levels of mRNA coding for Na,K-ATPase alpha and beta subunits in cultured neonatal rat cardiocytes. We measured intracellular Na+ levels ([Na+]i) in cardiocytes using a Na(+)-sensitive fluorescence dye (SBFI). 1 mM ouabain caused a significant increase in [Na+]i in cardiocytes; from 12.8 +/- 0.3 to 28.8 +/- 1.8 mM. Exposure of cardiocytes to 1 mM ouabain resulted in a three- to fourfold increase in alpha 1, alpha 2, and alpha 3 mRNA accumulation, and an approximate two-fold increase in beta 1 mRNA accumulation. A maximum elevation was reached at 60 min in both cases. The ouabain-induced alpha 1 mRNA accumulation was still observed in the Ca(2+)-free culture medium. Exposure of cardiocytes to 10 microM monensin in the absence of extracellular Ca2+ also resulted in a threefold increase in alpha 1 mRNA accumulation. The increased alpha 1 mRNA expression by 1 mM ouabain was associated with a fourfold increase in alpha 1 subunit protein accumulation. Transfection experiments with chimeric plasmids containing 5'-flanking sequences of alpha 1, alpha 2, and alpha 3 isoform genes and a luciferase reporter gene revealed that 1 mM ouabain caused a twofold increase in luciferase activity in each alpha system. These results suggest that Na+ directly regulates Na,K-ATPase gene expression in cardiocytes. The transfection study further supports the premise that Na(+)-responsive elements are located within the 5'-flanking sequences of each alpha isoform gene.

Synergistic effects of injection of bone marrow cells into both portal vein and bone marrow on tolerance induction in transplantation of allogeneic pancreatic islets.

We have established a new method for allogeneic pancreatic islet (PI) transplantation: relatively low doses of irradiation followed by simultaneous transplantation of PIs and bone marrow cells (BMCs) via the portal vein (PV). In the present study, we have compared this method with intra-bone marrow (IBM)-bone marrow transplantation (BMT), and with a combination of both methods. Streptozotocin (STZ)-induced diabetic-recipient rats, Fischer 344 (F344, RT1A(l), RT1B(l)), were irradiated 1 day before transplantation. PIs of Brown Norway rats (BN, RT1A(n), RT1B(n)) were transplanted into the liver of the diabetic F344 rats via the PV. BMCs from BN rats were injected into the recipients' bone marrow (IBM), PV or intravenously (IV) or by a simultaneous combination of PV plus IBM (PV+IBM). We compared graft survival among the groups of '9 Gy+IBM'(10/10 accepted), '9 Gy+PV'(7/10 accepted), '9 Gy+IV'(0/7 accepted), '9 Gy+PV+IBM'(8/8 accepted), '8.5 Gy+IBM'(4/9 accepted), '8.5 Gy+PV'(0/7 accepted), '8.5 Gy+IV'(0/7 accepted), '8.5 Gy+PV+IBM'(9/12 accepted), '8 Gy+IBM'(2/10 accepted) and '8 Gy+PV+IBM'(2/8 accepted). As we reported previously, PV-BMT is more effective in inducing the acceptance of allogeneic PIs than IV-BMT. However, IBM-BMT requires less pretreatment than PV-BMT. (PV+IBM)-BMT was found to be the most effective in inducing the acceptance of allogeneic PIs. These results suggest that allogeneic PI-transplantation in conjunction with (PV+IBM)-BMT could become a viable strategy.