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.

Successful treatment of extramedullary tumors with low-dose thalidomide in patients with multiple myeloma

Extramedullary tumor (EMT) is a poor prognostic factor of multiple myeloma (MM). The majority of patients report poor efficacy of thalidomide in MM with EMT, and bortezomib is the preferred choice of treatment. We report two cases of MM with EMTs in which thalidomide was highly beneficial. Case 1 has been in remission for ten months with 100 mg every other day of thalidomide monotherapy, which is the lowest dose to be reported in a successfully treated case of MM with EMT. Case 2 eventually became refractory, but low dose thalidomide gave excellent disease control over a period of eleven weeks, despite the EMT being in a highly aggravated state. Some reports have speculated that EMT cases with preceding bone marrow transplantation (BMT) are an exception and have a good response to thalidomide, but the present two cases have no history of BMT. In conclusion, low dose thalidomide can be effective in MM with EMT and should be considered as a treatment option, especially in the elderly.

Choledochal cyst associated with duodenal atresia: case report and review of the literature

We report a rare case of choledochal cyst (CC) associated with congenital duodenal atresia (DA) and annular pancreas (AP). A girl was born at 37 weeks of gestation weighing 2,974 g with a prenatal diagnosis of DA. She underwent a duodenoduodenostomy for type III DA with an AP 1 day after birth. At 4 years of age, she was admitted for evaluation of cholangitis and pancreatitis. Radiological studies demonstrated a fusiform-type CC with pancreaticobiliary maljunction (PBMJ). Excision of the CC and hepaticojejunostomy were performed. The patient was discharged without complications. Despite the fact that CC, DA, and AP are embryologically closely related entities, to the best of our knowledge, only eight such cases have been documented. We must be aware of the possible combination of CC in the follow-up of the patients with DA associated with AP.

Enteropathy-Type T-Cell Lymphoma Expressing NK-Cell Intraepithelial Lymphocyte (NK-IEL) Phenotype

Enteropathy-type T-cell lymphoma (ETL) is an intraepithelial T-lymphocyte (T-IEL) tumor. The tumor cells are usually CD3+, CD4-, CD8+, and contain cytotoxic granule associated proteins. We report on a CD3-negative CD56-positive enteropathy-associated lymphoma (ETL). This is the first case report of CD3-negative, CD56-positive, CD94-negative, and CD161-positive ETL. ETL cells originate from intraepithelial T-lymphocytes of the intestine. CD3-negative intraepithelial lymphocytes are known as natural killer (NK)-IELs. The phenotype of NK-IELs is also CD3-negative, CD56-positive, CD94-negative, and CD161-positive, while most normal NK cells express CD56 and CD94. CD3-negative lymphoma cells in this report also expressed CD56 and CD161, but not CD94. Because Southern blotting analysis showed a rearrangement of T-cell receptor (TCR) Cbeta in this case, the tumor is classified as an ETL. Based on the findings, NK-IELs may originate from T-cells, not NK-cells.

High prevalence of vitamin K and D deficiency and decreased BMD in inflammatory bowel disease

SUMMARY

Vitamin K and D deficiency and decreased bone mineral density (BMD) were highly prevalent in patients with inflammatory bowel disease (IBD), especially Crohn's disease (CD). Dietary intakes of these vitamins, however, were above the Japanese adequate intakes in IBD patients, suggesting that malabsorption is the basis for hypovitaminosis K and D and decreased BMD.

INTRODUCTION

We have studied the possible involvement of vitamin K and D deficiency in the pathogenesis of decreased BMD in IBD.

METHODS

Seventy patients with IBD were evaluated for their BMD; plasma levels of vitamin K; phylloquinone (PK), menaquinone-7 (MK-7), and 25OH-D; serum PTH, protein induced by vitamin K absence (PIVKA-II), and undercarboxylated osteocalcin (ucOC) levels; and their food intake.

RESULTS

Compared with ulcerative colitis (UC) patients, CD patients had significantly lower plasma vitamin K and 25OH-D concentrations; significantly higher serum levels of PTH, PIVKA-II, and ucOC; and significantly lower BMD scores at almost all measurement sites. More IBD patients were vitamin K deficient in bone than in liver. Multiple regression analyses revealed that low plasma concentrations of vitamin K and 25OH-D were independent risk factors for low BMD and that they were associated with the patients' fat intake, but not with their intake of these vitamins.

CONCLUSION

IBD patients have high prevalence of decreased BMD and vitamin K and D deficiency probably caused by malabsorption of these vitamins.

Src activation generates reactive oxygen species and impairs metabolism-secretion coupling in diabetic Goto-Kakizaki and ouabain-treated rat pancreatic islets

AIMS/HYPOTHESIS

Na(+)/K(+)-ATPase inhibition by ouabain suppresses ATP production by generating reactive oxygen species (ROS) and impairs glucose-induced insulin secretion from pancreatic islets. To clarify the signal-transducing function of Na(+)/K(+)-ATPase in decreasing ATP production by the generation of ROS in pancreatic islets, the involvement of Src was examined. In addition, the significance of Src activation in diabetic islets was examined.

METHODS

Isolated islets from Wistar rats and diabetic Goto-Kakizaki (GK) rats (a model for diabetes) were used. ROS was measured by 5-(and 6)-chloromethyl-2',7'-dichlorofluorescein fluorescence using dispersed islet cells. After lysates were immunoprecipitated by anti-Src antibody, immunoblotting was performed.

RESULTS

Ouabain caused a rapid Tyr(418) phosphorylation, indicating activation of Src in the presence of high glucose. The specific Src inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2) restored the ouabain-induced decrease in ATP content and the increase in ROS production. Both PP2 and ROS scavenger restored the impaired insulin release and impaired ATP elevation in GK islets, but had no such effect in control islets. PP2 reduced the high glucose-induced increase in ROS generation in GK islet cells but had no effect on that in control islet cells. Moreover, ouabain had no effect on ATP content and ROS production in the presence of high glucose in GK islets.

CONCLUSIONS/INTERPRETATION

These results indicate that Src plays a role in the signal-transducing function of Na(+)/K(+)-ATPase, in which ROS generation decreases ATP production in control islets. Moreover, ROS generated by Src activation plays an important role in impaired glucose-induced insulin secretion in GK islets, in which Src is endogenously activated independently of ouabain.

Intracellular ABC transporter A3 confers multidrug resistance in leukemia cells by lysosomal drug sequestration

Multidrug resistance (MDR) seriously limits the efficacy of chemotherapy in patients with cancer and leukemia. Active transport across membranes is essential for such cellular drug resistance, largely provided by ATP-binding cassette (ABC) transport proteins. Intracellular drug sequestration contributes to MDR; however, a genuine intracellular ABC transport protein with MDR function has not yet been identified. Analyzing the intrinsic drug efflux capacity of leukemic stem cells, we found the ABC transporter A3 (ABCA3) to be expressed consistently in acute myeloid leukemia (AML) samples. Greater expression of ABCA3 is associated with unfavorable treatment outcome, and in vitro, elevated expression induces resistance toward a broad spectrum of cytostatic agents. ABCA3 remains localized within the limiting membranes of lysosomes and multivesicular bodies, in which cytostatics are efficiently sequestered. In addition to AML, we also detected ABCA3 in a panel of lymphohematopoietic tissues and transformed cell lines. In conclusion, we identified subcellular drug sequestration mediated by the genuinely intracellular ABCA3 as being a clinically relevant mechanism of intrinsic MDR.

Soluble TNF receptors and albuminuria in non-obese Japanese type 2 diabetic patients

The aim of this study was to investigate the relationships between albuminuria and tumor necrosis factor (TNF)-alpha or soluble TNF receptors (sTNF-R1, sTNF-R2) in eighty-eight non-obese Japanese type 2 diabetic patients stratified into two groups according to albuminuria status-microalbuminuria or normoalbuminuria. Patients with microalbuminuria were older and had significantly higher concentrations of sTNF-R1 and sTNF-R2 than those with normoalbuminuria. There was, however, no significant difference in sex, diabetes duration, smoking, BMI, systolic and diastolic blood pressure, HbA (1c), serum creatinine, and lipid profile between the two groups. Although serum TNF-alpha was positively correlated to serum sTNF-R1 and sTNF-R2, serum TNF-alpha level did not differ with respect to albuminuria. Univariate regression analysis showed that urinary albumin concentration was positively correlated to age (r=0.380, p<0.001), serum creatinine (r=0.214, p<0.05) and concentrations of sTNF-R1 (r=0.364, p<0.001) and sTNF-R2 (r=0.342, p<0.005). Other variables, including TNF-alpha, were not associated with albuminuria. Multiple regression analyses showed that urinary albumin concentration was independently predicted by the level of sTNF-R1 (F=32.1), which explained 26.3% of the variability of urinary albumin concentration. From these results, it can be concluded that serum soluble TNF receptor is an important independent factor associated with albuminuria in non-obese Japanese type 2 diabetic patients.

Methylation status analysis of cell cycle regulatory genes (p16INK4A, p15INK4B, p21Waf1/Cip1, p27Kip1 and p73) in natural killer cell disorders

Natural killer (NK) cell disorders are rare diseases. Genetic abnormalities of the several tumor suppressor genes, including p15INK4B, p16INK4A/p14ARF, p53, p73, and Rb genes have been reported. Deletions and point mutations of these genes are frequently detected in these diseases. It has been reported that tumor suppressor genes are inactivated by DNA methylation of the promoter region and/or first exon of the genes in a variety of human cancers. In this study we analyze the methylation status of the genes associated with cell cycle regulation, including p16INK4A, p15INK4B, p21/Waf1/Cip1, p27/Kip1, p73, and p14ARF, by methylation specific (MS) PCR and/or bisulfite sequencing. We examined 29 cases of NK cell disorders (five aggressive NK cell leukemia/lymphoma, three blastic NK cell lymphoma/leukemia, five nasal NK cell lymphoma, three myeloid/NK cell precursor acute leukemia, 13 chronic NK lymphocytosis). We found methylation of the first exon of the p16INK4A gene in two cases (one aggressive, one blastic), and methylation of the p14ARF gene in one aggressive NK cell leukemia. Bisulfite sequencing revealed that methylation of the p15 and p27 genes was rare in these disorders. MS-PCR suggested that the p73 and p21 genes were methylated in seven cases, respectively (p73: one blastic, one nasal, five chronic; p21: one myeloid/NK, one aggressive, one nasal, and four chronic); bisulfite sequencing confirmed that methylated alleles of these genes were dominant in the samples except three cases (one myeloid/NK, one aggressive, and one chronic) in which methylated alleles of the p21 genes were less than 34% of all alleles. These results suggested that inactivation of the cell cycle regulatory genes by DNA methylation could be associated with tumorigenesis in NK cell disorders, not only aggressive subtypes but also chronic subtype.

Expression of the exocytotic protein syntaxin in mouse oocytes

Syntaxin is an integral membrane protein that is involved in membrane fusion. The exocytosis of the contents of cortical granules, secretory vesicles located in the cortex of an egg, modify the extracellular environment to block additional spermatozoa from penetrating the newly fertilized egg. The aim of this study was to characterize syntaxin expression in mouse oocytes, and to determine the specific isoform that is expressed. Syntaxin was demonstrated in the mouse ovary and in mouse oocytes by both western blot and reverse transcription-polymerase chain reaction analyses. Syntaxin 4 was specifically expressed in metaphase II oocytes. Syntaxin was also immunolocalized within metaphase II oocytes and one-cell embryos with pronuclei using laser scanning confocal microscopy. In metaphase II oocytes, syntaxin was located on the plasma membrane and in the cortex, where cortical granules are present, but was not seen at sites free of cortical granules. In one-cell embryos, no cytoplasmic region was free of syntaxin immunoreactivity. Immunoelectron microscopy detected syntaxin on both the plasma membrane and the vesicle membranes in mouse metaphase II oocytes. In conclusion the results indicate that syntaxin 4 co-localizes with cortical granules and participates in membrane fusion and exocytosis during the cortical reaction.

Evaluation and characterization of mouse scratching behavior by a new apparatus, MicroAct

We evaluated and characterized the mouse scratching behavior using a new apparatus, MicroAct. Scratching behavior was evoked in ICR and BALB/c mice by compound 48/80, passive cutaneous anaphylaxis or repeated hapten application. Under the present experimental condition, MicroAct detected consecutive scratching behavior (events) consisting of 3 or more beats. Although the detecting standard of MicroAct was not identical to that of an observer, the number of events detected by MicroAct and by an observer were almost comparable with each other. Frequency of events, total scratching time and total number of beats detected by MicroAct increased depending on the intensity of the causing stimuli for scratching. In contrast, the duration of each event and the number of beats in each event increased only slightly, but the scratching speed was almost constant. The present results demonstrate that MicroAct is a useful tool for evaluating mouse scratching behavior. Mouse scratching behavior seems to have a relatively fixed pattern and the causing stimulus increases mainly in the frequency of event without affecting the scratching speed.