Long-term follow-up of the randomized trial of mesorectal excision with or without lateral lymph node dissection in rectal cancer (JCOG0212).

BACKGROUND: Japan Clinical Oncology Group (JCOG) 0212 (ClinicalTrials.gov NCT00190541) was a non-inferiority phase III trial of patients with clinical stage II-III rectal cancer without lateral pelvic lymph node enlargement. The trial compared mesorectal excision (ME) with ME and lateral lymph node dissection (LLND), with a primary endpoint of recurrence-free survival (RFS). The planned primary analysis at 5 years failed to confirm the non-inferiority of ME alone compared with ME and LLND. The present study aimed to compare ME alone and ME with LLND using long-term follow-up data from JCOG0212. METHODS: Patients with clinical stage II-III rectal cancer below the peritoneal reflection and no lateral pelvic lymph node enlargement were included in this study. After surgeons confirmed R0 resection by ME, patients were randomized to receive ME alone or ME with LLND. The primary endpoint was RFS. RESULTS: A total of 701 patients from 33 institutions were assigned to ME with LLND (351) or ME alone (350) between June 2003 and August 2010. The 7-year RFS rate was 71.1 per cent for ME with LLND and 70·7 per cent for ME alone (hazard ratio (HR) 1·09, 95 per cent c.i. 0·84 to 1·42; non-inferiority P = 0·064). Subgroup analysis showed improved RFS among patients with clinical stage III disease who underwent ME with LLND compared with ME alone (HR 1·49, 1·02 to 2·17). CONCLUSION: Long-term follow-up data did not support the non-inferiority of ME alone compared with ME and LLND. ME with LLND is recommended for patients with clinical stage III disease, whereas LLND could be omitted in those with clinical stage II tumours.

ANTECEDENTES: El JCOG0212 (ClinicalTrials.gov: NCT00190541) fue un ensayo fase III de no inferioridad en pacientes con cáncer de recto en estadio clínico II/III sin ganglios linfáticos aumentados de tamaño en la pared pélvica lateral. El ensayo comparó la escisión del mesorrecto (mesorectal excision, ME) con la ME con disección de los ganglios linfáticos laterales (lateral lymph node dissection, LLND), siendo el criterio de valoración principal la supervivencia libre de recidiva (recurrence free survival, RFS). El análisis primario planificado a los 5 años de seguimiento no pudo confirmar la no inferioridad de la ME frente a la ME con LLND. Este estudio tuvo como objetivo comparar la ME como procedimiento único y la ME con LLND utilizando datos de seguimiento a largo plazo del ensayo JCOG0212. MÉTODOS: En este estudio se incluyeron pacientes con cáncer de recto en estadio clínico II/III por debajo de la reflexión peritoneal sin ganglios linfáticos aumentados de tamaño en la pared pélvica lateral. Después de que los cirujanos confirmaran la resección R0 mediante la ME, los pacientes fueron asignados al azar al brazo de ME sola o al brazo de ME con LLND. El criterio de valoración principal fue la supervivencia libre de recidiva (RFS). RESULTADOS: Un total de 701 pacientes de 33 instituciones fueron asignados al azar para ser tratados mediante una ME con LLND (n = 351) o EM sola (n = 350) entre junio de 2003 y agosto de 2010. Las tasas de RFS a 7 años fueron del 71,1% para ME con LLND y 70,7 % para ME sola (cociente de riesgos instantáneos, hazard ratio, HR: 1,09 (i.c. del 95% 0,84-1,42), no inferioridad P = 0,064)). El análisis de subgrupos mostró una mejor RFS entre los pacientes en estadio clínico III que se sometieron a ME con LLND en comparación con ME sola (HR: 1,49 (i.c. del 95%: 1,02-2,17)). CONCLUSIÓN: Los datos de seguimiento a largo plazo no justificaron la no inferioridad de la ME en comparación con la ME con LLND. Se recomienda la ME con LLND para pacientes en estadio clínico III, mientras que LLND podría omitirse para pacientes en estadio clínico II.

Effect of sodium-glucose co-transporter-2 inhibitors on impaired ventricular repolarization in people with Type 2 diabetes.

AIMS: To test the hypothesis that treatment with a sodium-glucose co-transporter-2 inhibitor would reverse ventricular repolarization heterogeneity, a predictor of cardiovascular mortality, in people with Type 2 diabetes. METHODS: We retrospectively analysed changes in indices of ventricular repolarization before and after treatment with a sodium-glucose co-transporter-2 inhibitor in 46 people with Type 2 diabetes. RESULTS: Sodium-glucose co-transporter-2 inhibitor treatment reduced HbA1c concentration [62±13 mmol/mol (7.7±1.2%) vs 59±16 mmol/mol (7.5±1.4%)], body weight (77.8±13.9 vs 74.7±12.5 kg) and systolic blood pressure (133±18 vs 126±12 mmHg) in the study participants. Heart rate and QTc interval were not changed by sodium-glucose co-transporter-2 inhibitor treatment, but QTc dispersion was significantly reduced (median, 48.8 vs 44.2 ms). Sodium-glucose co-transporter-2 inhibitor treatment reversed QTc dispersion more in participants who had larger QTc dispersion before the treatment. Changes in systolic blood pressure (Spearman's ρ= 0.319; P=0.031), but not in HbA1c concentration, were correlated with changes in QTc dispersion after sodium-glucose co-transporter-2 inhibitor treatment. CONCLUSIONS: The findings suggest that sodium-glucose co-transporter-2 inhibitor treatment reverses ventricular repolarization heterogeneity in people with Type 2 diabetes, independently of its effect on glycaemic control. The favourable effect on ventricular repolarization heterogeneity could be the mechanism by which empaglifozin reduced cardiovascular events in a recent study.

ACTN4 copy number increase as a predictive biomarker for chemoradiotherapy of locally advanced pancreatic cancer.

BACKGROUND: Several clinical trials have compared chemotherapy alone and chemoradiotherapy (CRT) for locally advanced pancreatic cancer (LAPC) treatment. However, predictive biomarkers for optimal therapy of LAPC remain to be identified.We retrospectively estimated amplification of the ACTN4 gene to determine its usefulness as a predictive biomarker for LAPC. METHODS: The copy number of ACTN4 in 91 biopsy specimens of LAPC before treatment was evaluated using fluorescence in situ hybridisation (FISH). RESULTS: There were no statistically significant differences in overall survival (OS) or progression-free survival (PFS) of LAPC between patients treated with chemotherapy alone or with CRT. In a subgroup analysis of patients treated with CRT, patients with a copy number increase (CNI) of ACTN4 had a worse prognosis of OS than those with a normal copy number (NCN) of ACTN4 (P=0.0005, log-rank test). However, OS in the subgroup treated with chemotherapy alone was not significantly different between patients with a CNI and a NCN of ACTN4. In the patients with a NCN of ACTN4, the median survival time of PFS in CRT-treated patients was longer than that of patients treated with chemotherapy alone (P=0.049). CONCLUSIONS: The copy number of ACTN4 is a predictive biomarker for CRT of LAPC.

MicroRNA-18a modulates STAT3 activity through negative regulation of PIAS3 during gastric adenocarcinogenesis.

BACKGROUND: MicroRNA (miRNA, miR)-18a is a member of the miR-17-92 cluster, an important locus that is markedly overexpressed in several cancers and associated with cancer development and progression. However, the mechanism of action of the miR-17-92 cluster and its individual miRNAs are largely unknown. METHODS AND RESULTS: In this study, we investigated the expression of the miR-17-92 cluster by in situ hybridisation (ISH) assay and copy-number analysis in gastric tissue microarray (TMA) specimens. We determined that miR-18a was present at higher levels than the other five miRNAs in the cluster. In addition, we identified Protein Inhibitor of Activated Signal Transducer and Activator of Transcription 3 (PIAS3) as a direct target of miR-18a in gastric cancer. miR-18a level was positively correlated with levels of Survivin, Bcl-xL, and c-Myc, which are downstream transcriptional targets of Signal Transducer and Activator of Transcription 3 (STAT3). STAT3-induced transcription can be negatively regulated by PIAS3; consistent with this, PIAS3 level was negatively correlated with levels of Survivin, Bcl-xL, and c-Myc. CONCLUSION: Our findings indicate that miR-18a acts as an oncogene and plays a role in gastric adenocarcinogenesis, at least in part by negatively regulating PIAS3 and thereby modulating expression of STAT3 target genes.

One-stage focal cartilage defect treatment with bone marrow mononuclear cells and chondrocytes leads to better macroscopic cartilage regeneration compared to microfracture in goats.

OBJECTIVE: The combination of chondrocytes and mononuclear fraction (MNF) cells might solve the expansion induced dedifferentiation problem of reimplanted cells in autologous chondrocytes implantation as sufficient cells would be available for direct, one-stage, implantation. Earlier in vitro work already showed a positive stimulation of cartilage specific matrix production when chondrocytes and MNF cells were combined. Therefore, this study aimed to evaluate cartilage regeneration using a one-stage procedure combining MNF cells and primary chondrocytes for the treatment of focal cartilage lesions in goats compared to microfracture treatment. DESIGN: Freshly created focal cartilage defects were treated with either a combination of chondrocytes and MNF cells embedded in fibrin glue or microfracture treatment. After 6 months follow-up local regeneration as well as the general joint cartilage health were evaluated using validated scores and biochemical assays. RESULTS: Macroscopic (P = 0.015) scores for the cartilage surface at the treated defect were, after 6 months, significantly higher for the chondrocyteMNF treatment compared to microfracture-treated defects, but microscopic scores were not (P = 0.067). The articulating cartilage showed more (P = 0.005) degeneration following microfracture treatment compared to chondrocyteMNF treatment. Biochemical glycosaminoglycans (GAG) evaluation did not reveal differences between the treatments. Both treatments had resulted in a slight to moderate cartilage degeneration at other locations in the joint. CONCLUSION: In conclusion, treatment of focal articular cartilage lesions in goats using a combination of MNF cells from bone marrow and unexpanded chondrocytes leads to better macroscopic regeneration compared to microfracture, however needs further fine-tuning to decrease the negative influence on other joint compartments.

Delayed gadolinium enhanced MRI of cartilage (dGEMRIC) can be effectively applied for longitudinal cohort evaluation of articular cartilage regeneration.

OBJECTIVE: Delayed gadolinium enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) facilitates non-invasive evaluation of the glycosaminoglycan content in articular cartilage. The primary aim of this study was to show that the dGEMRIC technique is able to monitor cartilage repair following regenerative cartilage treatment. DESIGN: Thirty-one patients with a focal cartilage lesion underwent a dGEMRIC scan prior to cartilage repair surgery and at 3 and 12 months follow-up. At similar time points clinical improvement was monitored using the Knee injury and Osteoarthritis Outcome Score (KOOS) and Lysholm questionnaires. Per MRI scan several regions-of-interest (ROIs) were defined for different locations in the joint. The dGEMRIC index (T1gd) was calculated for each ROI. Repeated-measures analysis of variance (RMANOVA) analysis was used to evaluate improvement in clinical scores and MRI T1gd over time. Also regression analysis was performed to show the influence of local repair on cartilage quality at distant locations in the knee. RESULTS: Clinical scores and the dGEMRIC T1gd per ROI showed a statistically significant improvement (P < 0.01), from baseline, at 12 months follow-up. Also, improvement from baseline in T1gd of the ROI defining the treated cartilage defect showed a direct relationship (P < 0.007) to the improvement of the T1gd of ROI at other locations in the joint. CONCLUSIONS: The dGEMRIC MRI protocol is a useful method to evaluate cartilage repair. In addition, local cartilage repair influenced the cartilage quality at other location in the joint. These findings validate the use of dGEMRIC for non-invasive evaluation of the effects of cartilage regeneration.

dGEMRIC as a tool for measuring changes in cartilage quality following high tibial osteotomy: a feasibility study.

OBJECTIVE: The high tibial osteotomy (HTO) is an effective strategy for treatment of painful medial compartment knee osteoarthritis. Effects on cartilage quality are largely unknown. Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) enables non-invasive assessment of cartilage glycosaminoglycan content. This study aimed to evaluate if dGEMRIC could detect relevant changes in cartilage glycosaminoglycan content following HTO. DESIGN: Ten patients with medial compartment osteoarthritis underwent a dGEMRIC scan prior to HTO, and after bone healing and subsequent hardware removal. A dGEMRIC index (T1Gd) was used for changes in cartilage glycosaminoglycan content, a high T1Gd indicating a high glycosaminoglycan content and vice versa. Radiographic analysis included mechanical axis and tibial slope measurement. clinical scores [knee osteoarthritis outcome scale (KOOS), visual analogue score (VAS) for pain, Knee Society clinical rating system (KSCRS)] before, 3 and 6 months after HTO and after hardware removal were correlated to T1Gd changes. RESULTS: Overall a trend towards a decreased T1Gd, despite HTO, was observed. Before and after HTO, lateral femoral condyle T1Gd was higher than medial femoral condyle (MFC) T1Gd and tibial cartilage T1Gd was higher than that of femoral cartilage (P < 0.001). The MFC had the lowest T1Gd before and after HTO. Clinical scores all improved significantly (P < 0.01), KOOS Symptoms and QOL were moderately related to changes in MFC T1Gd. CONCLUSIONS: dGEMRIC effectively detected differences in cartilage quality within knee compartments before and after HTO, but no changes due to HTO were detected. Hardware removal post-HTO seems essential for adequate T(1)Gd interpretation. T(1)Gd was correlated to improved clinical scores on a subscore level only. Longer follow-up after HTO may reveal lasting changes. ClinicalTrials.gov registration ID: NCT01269944.

Computerized testing augments pencil-and-paper tasks in measuring HIV-associated mild cognitive impairment(*).

BACKGROUND: Existing tools for rapid cognitive assessment in HIV-positive individuals with mild cognitive deficits lack sensitivity or do not meet psychometric requirements for tracking changes in cognitive ability over time. METHODS: Seventy-five nondemented HIV-positive patients were evaluated with the Montreal Cognitive Assessment (MoCA), a brief battery of standardized neuropsychological tests, and computerized tasks evaluating frontal-executive function and processing speed. Rasch analyses were applied to the MoCA data set and subsequently to the full set of data from all tests. RESULTS: The MoCA was found to adequately measure cognitive ability as a single, global construct in this HIV-positive cohort, although it showed poorer precision for measuring patients of higher ability. Combining the additional tests with the MoCA resulted in a battery with better psychometric properties that also better targeted the range of abilities in this cohort. CONCLUSION: This application of modern test development techniques shows a path towards a quick, quantitative, global approach to cognitive assessment with promise both for initial detection and for longitudinal follow-up of cognitive impairment in patients with HIV infection.

Tumor necrosis factor production during human renal allograft rejection is associated with depression of plasma protein C and free protein S levels and decreased intragraft thrombomodulin expression.

Fibrin deposition is a common accompaniment of renal allograft rejection, indicating disruption of the normal physiologic balance between procoagulant and anticoagulant pathways. In vitro, tumor necrosis factor (TNF) induces endothelial expression of the procoagulant, tissue factor, and downregulation of thrombomodulin, a key component of the thrombomodulin/protein C (PC)/protein S (PS) pathway, which normally maintains an anticoagulant state by inactivating thrombin, preventing further thrombin formation by degrading factors Va and VIIIa, and decreasing plasminogen activator inhibitor activity. Raised levels of TNF were recently demonstrated within the blood of patients during episodes of renal allograft injection, and may be an early and discriminatory marker of rejection. This led us to investigate prospectively whether monitoring of serum TNF levels was of value clinically, and was associated with effects on circulating PC and PS levels, or alterations in intragraft thrombomodulin expression. Plasma samples (n = 454) were collected three times/week from all patients (n = 25) undergoing renal transplantation during a 9-month consecutive period, and assayed by ELISA and functional assays for TNF, PC, and free PS (FPS). Portions of renal biopsies, taken to evaluate episodes of acute deterioration of renal function, were evaluated by immunoperoxidase labeling for the presence and distribution of TNF, thrombomodulin, PC, PS, thrombin, fibrin, and factors V and VIII. Comparison of 78 plasma samples collected during 26 episodes of biopsy-proven acute cellular rejection with samples collected during periods of stable renal function (n = 349) showed that TNF levels rose significantly (390 +/- 242 pg/ml, p less than 0.01) above background levels 3 days before rising serum creatinine concentrations, and peaked (2,426 +/- 978 pg/ml) on the day of clinical rejection. PC-antigen (Ag) concentrations also decreased 3 days before rejection (68 +/- 13%, p less than 0.05), and were maximally depressed (49% +/- 16%, p less than 0.001) on the day of rejection. FPS levels were normal until the day before rejection (63% +/- 8%, p less than 0.01) and, like PC, were maximally depressed (43 +/- 10%) at rejection. Plasma TNF levels were significantly and inversely correlated with PC-Ag (p less than 0.001) and FPS (p less than 0.005) levels during rejection, regardless of whether such rejection episodes were steroid responsive or required OKT3 monoclonal antibody therapy. TNF, PC, and FPS levels were normal during episodes of cyclosporine toxicity and viral infection.(ABSTRACT TRUNCATED AT 400 WORDS)

Quality of scaffold fixation in a human cadaver knee model.

OBJECTIVE: Newly developed regenerative cartilage interventions based on the application of 3D-scaffolds require a further evaluation of the surgical techniques involved. The present study compared four different scaffold fixation techniques [fibrin glue (FG), transosseous (TS) fixation, biodegradable pin (BP) fixation and continuous cartilage sutures (CS)] to implant a custom-printed porous PEOT/PBT1000/70/30 scaffold in a human cadaver knee model. METHODS: After implantation, the knees were subjected to a vertically oriented loaded continuous passive motion (CPM) protocol. The fixation techniques were evaluated after 60 and a subsequent 150 motion cycles, focusing on area coverage, outline attachment and scaffold integrity. After the total of 210 cycles, also an endpoint fixation test was performed. RESULTS: The fixation techniques revealed marginal differences for area coverage and outline attachment after 60 and 150 cycles. The FG scored higher on scaffold integrity compared to TS (P<0.05) and CS (P=0.01). Endpoint fixation was highest for the CS, whereas FG showed a weak final fixation strength (P=0.01). CONCLUSIONS: This study showed that optimal fixation cannot be combined always with high scaffold integrity. Special attention devoted to scaffold properties in relation to the fixation technique may result in an improvement of scaffold fixation, and thus clinical cartilage regenerative approaches involving these scaffolds.

Chronic administration of DSP-7238, a novel, potent, specific and substrate-selective DPP IV inhibitor, improves glycaemic control and beta-cell damage in diabetic mice.

AIMS: The purpose of this study is to assess the in vitro enzyme inhibition profile of DSP-7238, a novel non-cyanopyrrolidine dipeptidyl peptidase (DPP) IV inhibitor and to evaluate the acute and chronic effects of this compound on glucose metabolism in two different mouse models of type 2 diabetes. METHODS: The in vitro enzyme inhibition profile of DSP-7238 was assessed using plasma and recombinant enzymes including DPP IV, DPP II, DPP8, DPP9 and fibroblast activation protein alpha (FAPalpha) with fluorogenic substrates. The inhibition type was evaluated based on the Lineweaver-Burk plot. Substrate selectivity of DSP-7238 and comparator DPP IV inhibitors (vildagliptin, sitagliptin, saxagliptin and linagliptin) was evaluated by mass spectrometry based on the changes in molecular weight of peptide substrates caused by release of N-terminal dipeptides. In the in vivo experiments, high-fat diet-induced obese (DIO) mice were subjected to oral glucose tolerance test (OGTT) following a single oral administration of DSP-7238. To assess the chronic effects of DSP-7238 on glycaemic control and pancreatic beta-cell damage, DSP-7238 was administered for 11 weeks to mice made diabetic by a combination of high-fat diet (HFD) and a low-dose of streptozotocin (STZ). After the dosing period, HbA1c was measured and pancreatic damage was evaluated by biological and histological analyses. RESULTS: DSP-7238 and sitagliptin both competitively inhibited recombinant human DPP IV (rhDPP IV) with K(i) values of 0.60 and 2.1 nM respectively. Neither vildagliptin nor saxagliptin exhibited competitive inhibition of rhDPP IV. DSP-7238 did not inhibit DPP IV-related enzymes including DPP8, DPP9, DPP II and FAPalpha, whereas vildagliptin and saxagliptin showed inhibition of DPP8 and DPP9. Inhibition of glucagon-like peptide-1 (GLP-1) degradation by DSP-7238 was apparently more potent than its inhibition of chemokine (C-X-C motif) ligand 10 (IP-10) or chemokine (C-X-C motif) ligand 12 (SDF-1alpha) degradation. In contrast, vildagliptin and saxagliptin showed similar degree of inhibition of degradation for all the substrates tested. Compared to treatment with the vehicle, single oral administration of DSP-7238 dose-dependently decreased plasma DPP IV activity and improved glucose tolerance in DIO mice. In addition, DSP-7238 significantly decreased HbA1c and ameliorated pancreatic damage following 11 weeks of chronic treatment in HFD/STZ mice. CONCLUSIONS: We have shown in this study that DSP-7238 is a potent DPP IV inhibitor that has high specificity for DPP IV and substrate selectivity against GLP-1. We have also found that chronic treatment with DSP-7238 improves glycaemic control and ameliorates beta-cell damage in a mouse model with impaired insulin sensitivity and secretion. These findings indicate that DSP-7238 may be a new therapeutic agent for the treatment of type 2 diabetes.

Inhibition of RXR and PPARgamma ameliorates diet-induced obesity and type 2 diabetes.

PPARgamma is a ligand-activated transcription factor and functions as a heterodimer with a retinoid X receptor (RXR). Supraphysiological activation of PPARgamma by thiazolidinediones can reduce insulin resistance and hyperglycemia in type 2 diabetes, but these drugs can also cause weight gain. Quite unexpectedly, a moderate reduction of PPARgamma activity observed in heterozygous PPARgamma-deficient mice or the Pro12Ala polymorphism in human PPARgamma, has been shown to prevent insulin resistance and obesity induced by a high-fat diet. In this study, we investigated whether functional antagonism toward PPARgamma/RXR could be used to treat obesity and type 2 diabetes. We show herein that an RXR antagonist and a PPARgamma antagonist decrease triglyceride (TG) content in white adipose tissue, skeletal muscle, and liver. These inhibitors potentiated leptin's effects and increased fatty acid combustion and energy dissipation, thereby ameliorating HF diet-induced obesity and insulin resistance. Paradoxically, treatment of heterozygous PPARgamma-deficient mice with an RXR antagonist or a PPARgamma antagonist depletes white adipose tissue and markedly decreases leptin levels and energy dissipation, which increases TG content in skeletal muscle and the liver, thereby leading to the re-emergence of insulin resistance. Our data suggested that appropriate functional antagonism of PPARgamma/RXR may be a logical approach to protection against obesity and related diseases such as type 2 diabetes.

Essential role of insulin receptor substrate 1 (IRS-1) and IRS-2 in adipocyte differentiation.

To investigate the role of insulin receptor substrate 1 (IRS-1) and IRS-2, the two ubiquitously expressed IRS proteins, in adipocyte differentiation, we established embryonic fibroblast cells with four different genotypes, i.e., wild-type, IRS-1 deficient (IRS-1(-/-)), IRS-2 deficient (IRS-2(-/-)), and IRS-1 IRS-2 double deficient (IRS-1(-/-) IRS-2(-/-)), from mouse embryos of the corresponding genotypes. The abilities of IRS-1(-/-) cells and IRS-2(-/-) cells to differentiate into adipocytes are approximately 60 and 15%, respectively, lower than that of wild-type cells, at day 8 after induction and, surprisingly, IRS-1(-/-) IRS-2(-/-) cells have no ability to differentiate into adipocytes. The expression of CCAAT/enhancer binding protein alpha (C/EBPalpha) and peroxisome proliferator-activated receptor gamma (PPARgamma) is severely decreased in IRS-1(-/-) IRS-2(-/-) cells at both the mRNA and the protein level, and the mRNAs of lipoprotein lipase and adipocyte fatty acid binding protein are severely decreased in IRS-1(-/-) IRS-2(-/-) cells. Phosphatidylinositol 3-kinase (PI 3-kinase) activity that increases during adipocyte differentiation is almost completely abolished in IRS-1(-/-) IRS-2(-/-) cells. Treatment of wild-type cells with a PI 3-kinase inhibitor, LY294002, markedly decreases the expression of C/EBPalpha and PPARgamma, a result which is associated with a complete block of adipocyte differentiation. Moreover, histologic analysis of IRS-1(-/-) IRS-2(-/-) double-knockout mice 8 h after birth reveals severe reduction in white adipose tissue mass. Our results suggest that IRS-1 and IRS-2 play a crucial role in the upregulation of the C/EBPalpha and PPARgamma expression and adipocyte differentiation.

Cardioprotective mechanism of ischemic preconditioning is impaired by postinfarct ventricular remodeling through angiotensin II type 1 receptor activation.

BACKGROUND: Activation of protein kinase C-linked receptors and subsequent opening of the mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel are crucial in preconditioning (PC). This study examined whether postinfarct ventricular remodeling interferes with the PC mechanism. METHODS AND RESULTS: Two weeks before isolation of hearts, rabbits underwent a sham operation or coronary ligation (COL) to induce remodeling. Isolated buffer-perfused hearts were subjected to 30-minute global ischemia/2-hour reperfusion, and infarct size was expressed as a percentage of the left ventricle (%I/LV), from which the scarred infarct by COL was excluded. Although %I/LV was similar in sham-operated and remodeled hearts (52.9+/-6.5% versus 45.8+/-5.2%), PC with 2 episodes of 5-minute ischemia protected sham-operated but not remodeled hearts (%I/LV=18.1+/-2.5% versus 54.8+/-2.9%, P<0.05). Infusion of valsartan (10 mg x kg(-1). d(-1), an angiotensin II type 1 (AT(1)) receptor blocker, for 2 weeks after COL prevented the ventricular remodeling and preserved the response to PC (%I/LV=27.4+/-3.8%), although valsartan alone did not change %I/LV. Diazoxide, a mitoK(ATP) channel opener, protected both sham-operated and remodeled hearts (%I/LV=14.1+/-3.1% and 8.3+/-3.6%). CONCLUSIONS: The myocardium remodeled after infarction is refractory to PC, which is probably due to interruption of cellular signaling by PC upstream of mitoK(ATP) channels. An AT(1) receptor blocker is beneficial not only for suppression of ventricular remodeling but also for preservation of the PC mechanism.

Brain-derived neurotrophic factor regulates glucose metabolism by modulating energy balance in diabetic mice.

We previously reported that brain-derived neurotrophic factor (BDNF) regulates both food intake and blood glucose metabolism in rodent obese diabetic models such as C57BL/KsJ-lepr(db)/lepr(db) (db/db) mice. To elucidate the effect of BDNF on glucose metabolism, we designed a novel pellet pair-feeding apparatus to eliminate the effect of appetite alteration on glucose metabolism. The apparatus was used to synchronize food intake precisely between BDNF-treated and vehicle-treated db/db mice. It was shown using this pellet pair-feeding apparatus that BDNF administered daily (20 mg x kg(-1) x day(-1)) to db/db mice significantly lowered blood glucose compared with pellet pair-fed db/db mice. To evaluate the effect of BDNF on insulin action, we used streptozotocin-induced type 1 diabetic mice. In this case, BDNF did not lower blood glucose concentration but rather enhanced the hypoglycemic action of insulin. In hyperglycemic db/db mice, pancreatic insulin content was reduced and glucagon content was increased compared with normoglycemic db/m mice. BDNF administered to db/db mice significantly restored both pancreatic insulin and glucagon content. Histological observations of aldehyde-fuchsin staining and immunostaining with anti-insulin indicated that insulin-positive pancreatic beta-cells were extensively regranulated by BDNF administration. We also studied the effect of BDNF on KK mice, normoglycemic animals with impaired glucose tolerance. In these mice, BDNF administration improved insulin resistance in the oral glucose tolerance test. To elucidate how blood glucose was metabolized in BDNF-treated animals, we investigated the effect of BDNF on the energy metabolism of db/db mice. Body temperature and oxygen consumption of the pellet pair-fed vehicle-treated mice were remarkably lower than the ad libitum-fed vehicle-treated mice. Daily BDNF administration for 3 weeks completely ameliorated both of the reductions. Finally, to clarify its action mechanism, the effect of intracerebroventricular administration of BDNF on db/db mice was examined. Here, a small dose of BDNF was found to be effective in lowering blood glucose concentration. This indicates that BDNF regulates glucose metabolism by acting directly on the brain.

Mitochondrial ATP-sensitive K+ channels play a role in cardioprotection by Na+-H+ exchange inhibition against ischemia/reperfusion injury.

OBJECTIVES: The possible role of the ATP-sensitive potassium (KATP) channel in cardioprotection by Na+-H+ exchange (NHE) inhibition was examined. BACKGROUND: The KATP channel is suggested to be involved not only in ischemic preconditioning but also in some pharmacological cardioprotection. METHODS: Infarction was induced by 30-min coronary occlusion in rabbit hearts in situ or by 30-min global ischemia in isolated hearts. Myocardial stunning was induced by five episodes of 5-min ischemia/5-min reperfusion in situ. In these models, the effects of NHE inhibitors (cariporide and ethylisopropyl-amiloride [EIPA]) and the changes caused by KATP channel blockers were assessed. In another series of experiments, the effects of EIPA on mitochondrial KATP (mito-KATP) and sarcolemmal KATP (sarc-KATP) channels were examined in isolated cardiomyocvtes. RESULTS: Cariporide (0.6 mg/kg) reduced infarct size in situ by 40%, and this effect was abolished by glibenclamide (0.3 mg/kg), a nonselective KATP channel blocker. In vitro, 1 microM cariporide limited infarct size by 90%, and this effect was blocked by 5-hydroxydecanoate (5-HD), a mito-KATP channel blocker but not by HMR1098, a sarc-KATP channel blocker. Infarct size limitation by 1 microM EIPA was also prevented by 5-HD. Cariporide attenuated regional contractile dysfunction by stunning, and this protection was abolished by glibenclamide and 5-HD. Ethylisopropyl amiloride neither activated the mito-KATP channel nor enhanced activation of this channel by diazoxide, a KATP channel opener. CONCLUSIONS: Opening of the mito-KATP channel contributes to cardioprotection by NHE inhibition, though the interaction between NHE and this KATP channel remains unclear.

Pretreatment with the adenosine A1 selective agonist, 2-chloro-N6-cyclopentyladenosine (CCPA), causes a sustained limitation of infarct size in rabbits.

OBJECTIVE: The highly selective adenosine A1 receptor agonist, 2-chloro-N6-cyclopentyl-adenosine (CCPA), has been shown to be as cardioprotective as ischaemic preconditioning when evaluated with an early staining method using tetrazolium. However, tetrazolium-positive tissue measured 3 h after reperfusion may still overestimate the long term salvage. To test for this possible artefact, a 72 h reperfusion rabbit model of myocardial infarction was used, and infarct size was assessed by histology. METHODS: Myocardial infarction was induced by a 30 min coronary occlusion. Rabbits were assigned to a control group receiving no treatment, pretreatment with 0.125 mg.kg-1 CCPA, or 0.25 mg.kg-1 pretreatment with CCPA (0.25 mg.kg-1) followed by an A1 selective antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) 30 min after reperfusion to reverse the haemodynamic side effects. RESULTS: In the 0.125 mg.kg-1 CCPA group, 30.8(SEM 4.2)% of the ischaemic zone was infarcted, which was significantly less than that seen in the control group [46.5(3.0)%; p < 0.01]. Reversing the side effects of CCPA by giving DPCPX soon after reperfusion did not block the protective effects [26.2(1.9)% infarction; p < 0.01 v control]. CONCLUSIONS: This finding confirms a genuine anti-infarct effect of adenosine A1 receptor stimulation when given prior to the onset of ischaemia. Furthermore blocking the A1 receptors soon after reperfusion reverses the side effects but does not block protection.

Role of adenosine receptor activation in myocardial infarct size limitation by ischaemic preconditioning.

OBJECTIVE: The aims were to examine the role of adenosine receptors in the mechanism of preconditioning in a chronic rabbit model of myocardial infarction; to assess whether the preconditioning effect is blocked by an adenosine receptor antagonist, 8-phenyltheophylline; and to determine whether an adenosine A1 receptor agonist, R(-)N6-2-phenylisopropyl adenosine (R-PIA), mimics infarct size limitation by preconditioning. METHODS: Myocardial infarction was induced in male rabbits by occlusion of the left coronary artery for 30 min, which was followed by 72 h reperfusion. Before the 30 min ischaemia, rabbits were subjected to one of the following six protocols: (1) untreated control; (2) intravenous injection of 8-phenyltheophylline; (3) preconditioning with 5 min ischaemia; (4) pretreatment with 8-phenyltheophylline plus preconditioning; (5) intravenous injection of R-PIA; or (6) R-PIA plus atrial pacing (240.min-1). Infarct size and area at risk were determined by histology and fluorescent particles, respectively. RESULTS: Preconditioning significantly limited infarct size, normalised as a percent of area at risk (%IS/AR), to 19.2 (SEM 2.3)% v control value of 46.5(2.8)%. 8-Phenyltheophylline alone did not modify the %IS/AR, but its injection before preconditioning attenuated the preconditioning effect such that IS/AR = 34.4(2.5)%. While R-PIA did not achieve statistically significant myocardial salvage, R-PIA plus atrial pacing limited infarct size to 33.7(3.0)% (p<0.05 v control). The R-PIA group had severe hypotension and their infarct sizes were inversely correlated with diastolic blood pressure at reperfusion. There was no such correlation in the R-PIA plus pacing group in which bradycardia and hypotension induced by R-PIA were attenuated by atrial pacing. CONCLUSIONS: The infarct size limiting effect of preconditioning was attenuated by 8-phenyltheophylline, and pretreatment with R-PIA was able to limit myocardial infarct size when severe hypotension was avoided by atrial pacing. These findings suggest that adenosine receptor activation plays a crucial role in the mechanism of preconditioning.