Curcumin improves insulin resistance in skeletal muscle of rats

BACKGROUND AND AIMS

Curcumin has been reported to lower plasma lipids and glucose in diabetic rats, and to decrease body weight in obese rats, which may partly be due to increased fatty acid oxidation and utilization in skeletal muscle.

METHODS AND RESULTS

Diabetic rats induced by high-fat diet plus streptozotocin (STZ, 30 mg/kg BW) were fed a diet containing 50, 150, or 250 mg/kg BW curcumin for 7 wk. Curcumin dose-dependently decreased plasma lipids and glucose and the dose 150 mg/kg BW appeared to be adequate to produce a significant effect. Curcumin supplementation reduced glucose and insulin tolerance measured as areas under the curve. L6 myotubes were treated with palmitate (0.25 mmol/L) in the presence of different levels of curcumin for 24 h in our in vitro experiment. Curcumin at 10 μmol/L was adequate to cause a significant increase in 2-deoxy-[(3)H]d-glucose uptake by L6 myotubes. Curcumin up-regulated expression of phosphorylated AMP-activated protein kinase (AMPK), CD36, and carnitine palmitoyl transferase 1, but down-regulated expression of pyruvate dehydrogenase 4 and phosphorylated glycogen synthase (GS) in both in vivo and in vitro studies. Moreover, curcumin increased phosphorylated acetyl COA carboxylase in L6 myotubes. The effects of curcumin on these enzymes except for GS were suppressed by AMPK inhibitor, Compound C. LKB1, an upstream kinase of AMPK, was activated by curcumin and inhibited by radicicol, an LKB1 destabilizer.

CONCLUSION

Curcumin improves muscular insulin resistance by increasing oxidation of fatty acid and glucose, which is, at least in part, mediated through LKB1-AMPK pathway.

Entacapone promotes cAMP-dependent colonic Cl(-) secretion in rats

BACKGROUND

Entacapone is a promising drug used widely for the treatment of Parkinson's disease (PD) as a catechol-O-methyl transferase (COMT) inhibitor. However, entacapone has gastrointestinal side effects. The aim of this study was to investigate the effects of entacapone on the epithelial ion transport in rat distal colon, and explore the underlying mechanism.

METHODS

The study was performed on freshly isolated colonic mucosa-only, submucosa-only and mucosa-submucosa preparations in rat. The short circuit current (I(SC) ) was measured to determine electrogenic ion transport, and a scanning ion-selective electrode technique (SIET) was used to directly measure Cl(-) flux across the epithelium. The content of intracellular cAMP was measured with radioimmunoassay (RIA).

KEY RESULTS

Entacapone increased mucosal I(SC) in the rat distal colon. I(SC) was inhibited significantly by apical addition of diphenylamine-2,2'-dicarboxylic acid (DPC), a blocker of the Cl(-) channel, basolateral application of bumetanide, an inhibitor of Na(+) -K(+) -2Cl(-) co-transporter (NKCC), removal of Cl(-) from the bathing solution, and pretreatment with MDL 12330A, an inhibitor of adenylate cyclase. Inhibiting endogenous prostaglandin (PG) synthesis with indomethacin, and eliminating submucosal enteric neural activity with tetrodotoxin (TTX)-inhibited entacapone-evoked I(SC) increases. Similar results were also obtained when Cl(-) flux was measured with SIET. Entacapone significantly increased intracellular cAMP content, which was greatly inhibited by either indomethacin or TTX in the tissues containing submucosal plexus, and by only indomethacin in the mucosa-only preparations.

CONCLUSIONS & INFERENCES

Entacapone stimulates cAMP-dependent Cl(-) secretion in the rat colon, and this process is regulated by endogenous PG and the submucosal enteric nervous system.

Outcomes of post-cataract surgery endophthalmitis referred to a tertiary center from local hospitals in the south of China

BACKGROUND

Endophthalmitis after cataract surgery is an uncommon but devastating complication. Prophylactic intracameral injection of cefuroxime 1 mg at the end of surgery decreases the incidence five-fold. The visual outcome can be good (53% of cases having a visual acuity [VA] of better than 20/40) if treatment is initiated rapidly and follows the Endophthalmitis Vitrectomy Study (EVS) guidelines; but even with the best treatment, some patients end up with a poor visual outcome. Previous studies on postoperative endophthalmitis mainly focus on the cases performed in metropolitan tertiary hospitals; however, little information is available on the cases performed in local hospitals in rural areas.

METHODS

We retrospectively reviewed the medical records of patients with acute endophthalmitis following cataract surgery, which were performed in local hospitals and later treated at the Zhongshan Ophthalmic Center between 1 January 1998 and 31 December 2009. Details of each case, including the interval from symptoms to presentation, initial treatment in local hospitals, microorganisms isolated, treatment, and visual outcome, were recorded. Cross-tabulations were conducted in order to identify the prognostic factors of final visual outcome.

RESULTS

Forty-six patients referred from 36 local hospitals and later treated at the Zhongshan Ophthalmic Center were reviewed over the audit period. Most of these cases occurred in April. Gram-positive bacteria were the predominant etiology, with fungal infection accounting for 15%. Even though 54% of patients had symptoms within 3 days post-cataract surgery, they did not present to a tertiary center until a mean of 10 days. The main initial treatment in local hospitals is systemic antibiotics, instead of the intravitreal injection of antibiotics. A high proportion of cases (27/46) received immediate pars plana vitrectomy (PPV) in the tertiary center, and the antibiotic used for intravitreal injection was mainly tobramycin. The final visual outcome was poor, with only three cases having a VA ≥20/40.

CONCLUSION

A relatively high rate of fungal endophthalmitis suggests that sterilization patterns in local hospitals should be further revised. A delayed presentation, inappropriate treatment procedures, poor presenting VA, and causative organism virulence may account for the unfavorable visual outcome in this study.

Plasma membrane-associated sialidase (NEU3) regulates progression of prostate cancer to androgen-independent growth through modulation of androgen receptor signaling

Prostate cancers generally become androgen-independent and resistant to hormone therapy with progression. To understand the underlying mechanisms and facilitate the development of novel treatments for androgen-independent prostate cancer, we have investigated plasma membrane-associated sialidase (NEU3), the key enzyme for ganglioside hydrolysis participating in transmembrane signaling. We have discovered NEU3 to be upregulated in human prostate cancer compared with non-cancerous tissue, correlating with the Gleason score. NEU3 silencing with siRNA in prostate cancer PC-3 and LNCaP cells resulted in increased expression of differentiation markers and in cell apoptosis, but decrease in Bcl-2 as well as a progression-related transcription factor, early growth response gene (EGR-1). In androgen-sensitive LNCaP cells, forced overexpression of NEU3 significantly induced expression of EGR-1, androgen receptor (AR) and PSA both with and without androgen, the cells becoming sensitive to androgen. The NEU3-mediated induction was abrogated by inhibitors for PI-3 kinase and MAP kinase and more specifically by their silencing in the absence of androgen, being confirmed by increased phosphorylation of AKT and ERK1/2 in NEU3 overexpressing cells. NEU3 siRNA introduction caused reduction of cell growth of an androgen-independent PC-3 cells in culture and of transplanted tumors in nude mice. These data suggest that NEU3 regulates tumor progression through AR signaling, and thus be a potential tool for diagnosis and therapy of androgen-independent prostate cancer.

The amount of surface HLA-I on T lymphocytes decreases in breast infiltrating ductal carcinoma patients

Human leucocyte antigen class I (HLA-I), which includes HLA-A, -B and -C, is an essential immune factor participating in the antitumour immune response. The changes in HLA-I expression in peripheral blood T lymphocytes in cancer patients have yet to be defined. This study examined the expression of HLA-I on CD4(+) and CD8(+) T lymphocytes in female patients with stage I - IV breast infiltrating ductal carcinoma, benign breast tumour diseases (mammary intraductal papilloma or breast fibroadenoma), and in healthy controls. HLA-I was down-regulated on CD4(+) T lymphocytes from patients with stage III and IV cancer, and on CD8(+) T lymphocytes in patients with stage I - IV cancer compared with healthy controls. HLA-I expression in T lymphocytes may contribute towards immune-balance disorders in tumour patients.

Colitogenic role of tumour necrosis factor (TNF) receptors in trinitrobenzene sulphonic acid colitis: TNF-R1 ablation does not affect systemic inflammatory response

Tumour necrosis factor (TNF)-α plays a critical role in the pathogenesis of T helper type 1-mediated colitis such as Crohn's disease. However, the roles of its two receptors in mediating pathology remain largely unknown. In this study, trinitrobenzene sulphonic acid (TNBS) was used to induce colitis in TNF-receptor single or double knock-out (DKO) BALB/c mice and in wild-type counterparts. TNF-R1(-/-) mice had significantly less weight loss, reduced mortality, colon shortening and oedema, colon histological damage and lower levels of colon myeloperoxidase compared with wild-type (WT) BALB/c mice. A similar manifestation was also observed in TNF-R2(-/-) and TNF-R1(-/-) TNF-R2(-/-) (TNF-R DKO) mice. Strikingly, systemic inflammatory response (including splenomegaly and monocyte expansion) was found in WT and TNF-R1(-/-) mice after TNBS, instead of TNF-R2(-/-) and TNF-R DKO mice. Attenuated pathology of colitis in TNF-R1(-/-) or TNF-R2(-/-) mice correlated with lower amounts of interleukin (IL)-6, IL-1β, monocyte chemotactic protein (MCP)-1, IL-12p70 and interferon (IFN)-γ production in the colons. Importantly, ablation of TNF-R1 or TNF-R2 reduced the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL)-positive apoptotic epithelial cells in the affected colons compared with WT TNBS-instilled controls, which might be due to the heightened ratio of Bcl-2/Bax and reduced activity of nuclear factor (NF)-κB. These findings suggest that either TNF-R1 or TNF-R2 plays a pathogenic role in the pathology of colitis and TNF signalling via TNF-R1 or TNF-R2 alone is not sufficient for inducing mucosal damage.

Shear stress induces a transient and VEGFR-2-dependent decrease in the motion of injected particles in endothelial cells

Vascular endothelial cells form the inner lining of all blood vessels and play a central role in vessel physiology and disease. Endothelial cells are highly responsive to the mechanical stimulus of fluid shear stress that is exerted by blood flowing over their surface. In this study, the immediate micromechanical response of endothelial cells to physiological shear stress was characterized by tracking of ballistically injected, sub-micron, fluorescent particles. It was found that the mean squared displacement (MSD) of the particles decreases by a factor 1.5 within 10 min after the onset of shear stress. This decrease in particle motion is transient, since the MSD returns to control values within 15-30 min after the onset of shear. The immediate micromechanical stiffening is dependent on activation of the vascular endothelial growth factor receptor (VEGFR)-2, because inhibition of the receptor abrogates the micromechanical response. This work shows that the cytoskeleton is actively involved in the acute, functional response of endothelial cells to shear stress.

cDNA cloning, genomic structure and mRNA expression pattern of porcine type I interferons receptor 2 gene

Type I interferons (IFN) are important mediators of the host defence against viruses through binding to the cell surface receptors, among which the binding to type I IFN receptor 2 (IFNAR2) is the very first step initiating a complex signal transduction cascade. By using RT-PCR and 5' RACE approaches, we obtained porcine IFNAR2 cDNA, the nucleotide identity of its coding region is 57.53%, 67.45%, 74.07% and 74.63% to those of mouse, human, sheep and cattle, respectively; and the deduced protein of which shares 38.18%, 55.29%, 62.01% and 63.39% identity to those of mouse, human, sheep and cattle, respectively. The genomic structure of porcine IFNAR2 gene consists of nine exons and eight introns. Porcine IFNAR2 mRNA expression was detected in all tissues examined, being strong in the spleen, small intestine, cerebrum and uterus tissues and relatively weak in the stomach tissues. As compared with piglets, the expression of IFNAR2 mRNA was significantly higher in both liver and spleen of Laiwu adult pigs (P < 0.01); in Duroc pigs, however, significantly higher IFNAR2 mRNA expression was only found in adult liver (P < 0.05). In Duroc × Landrace × Yorkshire commercial pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV), the expression of IFNAR2 mRNA in lung tissue was significantly down-regulated as compared to uninfected ones (P < 0.05).

Olfactory copy number association with age at onset of Alzheimer disease

OBJECTIVES

Copy number variants (CNVs) have been recognized as a source of genetic variation that contributes to disease phenotypes. Alzheimer disease (AD) has high heritability for occurrence and age at onset (AAO). We performed a cases-only genome-wide CNV association study for age at onset of AD.

METHODS

The discovery case series (n = 40 subjects with AD) was evaluated using array comparative genome hybridization (aCGH). A replication case series (n = 507 subjects with AD) was evaluated using Affymetrix array (n = 243) and multiplex ligation-dependent probe amplification (n = 264). Hazard models related onset age to CNV.

RESULTS

The discovery sample identified a chromosomal segment on 14q11.2 (19.3-19.5 Mb, NCBI build 36, UCSC hg18 March 2006) as a region of interest (genome-wide adjusted p = 0.032) for association with AAO of AD. This region encompasses a cluster of olfactory receptors. The replication sample confirmed the association (p = 0.035). The association was found for each APOE4 gene dosage (0, 1, and 2).

CONCLUSION

High copy number in the olfactory receptor region on 14q11.2 is associated with younger age at onset of AD.

A modified rat model for cannulation and collection of thoracic duct lymph

Difficulty in collecting lymph samples in small animals has impeded studies on lymphatic function and lymph composition. Here we report a simple and effective modified rat model for thoracic duct lymph drainage where animals remain in full consciousness and have free movement and access to water and food over 12 hours. The operative procedure required approximately 30 minutes to perform. Mean lymph drainage was 0.71 +/- 0.33 ml/h, and protein concentration did not change significantly (mean 37 +/- 2.59 mg/ml) over the 12 hours. However, the number of lymphocytes fluctuated widely between 0.08 +/- 0.03 x 10(6)/ml and 12.17 +/- 6.58 x 10(6)/ml. This modified animal model of thoracic duct lymph collection avoids influences of lipid intake, general anesthesia, or limited activity of animals on experimental outcomes, and therefore more accurately reflects lymph flow and composition under normal physiological conditions.