Hypermethylation of HLA class I gene is associated with HLA class I down-regulation in human gastric cancer

Down-regulated expression of human leukocyte antigen (HLA) class I molecules in many human cancers facilitate tumor cells to escape from immune attack. Promoter hypermethylation, one of the major epigenetic changes responsible for gene inactivation, plays an important role in gastric carcinogenesis. This study evaluated the expression and alteration of HLA class I molecules in a panel of 47 pairs of gastric cancer specimens with their noncancerous parts from Chinese patients by using immunohistochemistry (IHC), reverse transcription polymerase chain reaction (RT-PCR) and methylation-specific PCR (MSP) analysis. The expression of HLA-A, HLA-B/C and HLA class I complex was lost or down-regulated in human gastric cancer. The percentage of promoter methylation was 59.57% for HLA-A gene, 55.32% for HLA-B gene and 48.94% for HLA-C gene in gastric cancer, while it was decreased to 19.15%, 12.77% and 6.38% in the adjacent nontumor tissues, respectively. Seven of 10 (70%), 4 of 6 (66.7%) and 3 of 4 (75%) gastric cancer specimens with promoter hypermethylation at HLA-A, -B and -C loci showed transcriptional inactivation of HLA-A,-B and -C genes, suggesting an association between promoter hypermethylation and down-regulated expression of HLA class I molecules. Human gastric cancer cell line BGC-823 showed HLA-A down-regulation with promoter methylation of HLA-A locus. Treatment with DNA methyltransferase inhibitor restored the expression of HLA-A mRNA and surface HLA-A complex. Thus, our results showed that promoter hypermethylation might be one of the mechanisms that lead to HLA class I antigen down-regulation in gastric cancer.

Synergistic effect in treatment of C.I. Acid Red 2 by electrocoagulation and electrooxidation

An aqueous C.I. Acid Red 2 solution was decolorized by electrolysis using iron as anode. The decolorization mechanism was investigated through experimental observations on the electrochemical behavior of C.I. Acid Red 2 on Pt rotating disk electrode, UV-visible spectra of the solution and IR spectra of the coagulated mixtures. It is found that the decolorization efficiency is high, over 98.0% after 40 min, and this high decolorization efficiency can be ascribed to the synergistic effect of electrocoagulation and electrooxidation. The electrocoagulation results from the electrogenerated iron hydroxide and the electrooxidation results from electrogenerated ferric ions. The results obtained from IR spectra shows that the decolorization of C.I. Acid Red 2 by electrooxidation is due to the partial or complete cleavage of C-N bonds in C.I. Acid Red 2.

Hyperhomocysteinaemia, low folate concentrations and methylene tetrahydrofolate reductase C677T mutation in acute mesenteric venous thrombosis

OBJECTIVES

Acute mesenteric venous thrombosis (AMVT) was first reported by Fagge and was recognised as a distinct clinical entity by Warreen in 1935. However, its pathogenesis is still unclear. Elevated plasma levels of homocysteine (Hcy) are associated with an increased risk of deep vein thrombosis. This case-control study examines the potential association among hyperhomocysteinaemia (hyper-Hcy), low serum folate and vitamin B(12) levels and the common C677T mutation of the MTHFR gene in patients with AMVT.

MATERIALS AND METHODS

Sixty-three patients with AMVT and 75 sex- and age-matched healthy controls were recruited, and their plasma Hcy, folate and vitamin B(12) levels were measured by high performance liquid chromatography (HPLC) and immunological assays. The polymorphism of MTHFR C677T was detected by PCR-RFLP.

RESULTS

The mean plasma Hcy levels were significantly higher in patients with AVMT compared with controls (23.5 standard deviation (S.D.) 8.8 vs. 12.6+/-6.6micromoll(-1), P<0.01). The fasting Hcy correlated negatively with folate (AMVT: r=-0.42, P<0.01;

CONTROL

r=-0.40, P<0.01). The frequency of homozygous (TT) genotype in MTHFR C677T mutation was significantly higher in patients with AMVT than that in control subjects (33% vs. 17%; chi square (chi(2))=6.31, P<0.05; odds ratio (OR)=2.80; 95% confidence interval (CI): 1.25-6.25). Compared with the control subjects, the mean serum vitamin B(12) levels were lower in patients, but it was not statistically significant (365+/-88pmoll(-1) vs. 408+/-108pmoll(-1), P>0.05).

CONCLUSIONS

Hyper-Hcy and low serum folate levels were associated with an increased risk of AMVT. The homozygous (TT) genotype of MTHFR gene mutation may be a crucial hereditary risk factor in the development of AMVT for a Chinese population.

Cells deficient in the base excision repair protein, DNA polymerase beta, are hypersensitive to oxaliplatin chemotherapy

A significant proportion of human cancers overexpress DNA polymerase beta (Pol beta), the major DNA polymerase involved in base excision repair. The underlying mechanism and biological consequences of overexpression of this protein are unknown. We examined whether Pol beta, expressed at levels found in tumor cells, is involved in the repair of DNA damage induced by oxaliplatin treatment and whether the expression status of this protein alters the sensitivity of cells to oxaliplatin. DNA damage induced by oxaliplatin treatment of HCT116 and HT29 colon cancer cells was observed to be associated with the stabilization of Pol beta protein on chromatin. In comparison with HCT116 colon cancer cells, isogenic oxaliplatin-resistant (HCT-OR) cells were found to have higher constitutive levels of Pol beta protein, faster in vitro repair of a DNA substrate containing a single nucleotide gap and faster repair of 1,2-GG oxaliplatin adduct levels in cells. In HCT-OR cells, small interfering RNA knockdown of Pol beta delayed the repair of oxaliplatin-induced DNA damage. In a different model system, Pol beta-deficient fibroblasts were less able to repair 1,2-GG oxaliplatin adducts and were hypersensitive to oxaliplatin treatment compared with isogenic Pol beta-expressing cells. Consistent with previous studies, Pol beta-deficient mouse fibroblasts were not hypersensitive to cisplatin treatment. These data provide the first link between oxaliplatin sensitivity and DNA repair involving Pol beta. They demonstrate that Pol beta modulates the sensitivity of cells to oxaliplatin treatment.

Defective plasmacytoid dendritic cell-NK cell cross-talk in HIV infection

HIV viremia is associated with a wide range of immune dysfunctions that contribute to the immunocompromised state. HIV viremia has been shown to have a broad effect on several immune cell types and/or their interactions that are vital for mounting an effective immune response. In this study, we investigated the integrity of plasmacytoid dendritic cell (pDC)-NK cell interactions among HIV viremic, aviremic, and seronegative individuals. We describe a critical defect in the ability of pDCs from HIV-infected individuals to secrete IFN-alpha and TNF and subsequently activate NK cells. We also describe an inherent defect on NK cells from HIV-infected individuals to respond to pDC-secreted cytokines. Furthermore, we were able to demonstrate a direct effect of HIV trimeric gp120 on NK cells in vitro similar to that described ex vivo. Finally, we were able to establish that the HIV gp120-mediated suppressive effect on NK cells was a result of its binding to the integrin alpha(4)beta(7) expressed on NK cells. These findings suggest a novel mechanism by which HIV is capable of suppressing an innate immune function in infected individuals.

Diabetes mellitus after living donor liver transplantation: data from mainland China

Most reported data on posttransplantation diabetes mellitus (PTDM) are from Western countries with patients who underwent deceased donor liver transplantation. A retrospective study was performed to assess the prevalence and predictive factors of PTDM in the context of living donor liver transplantation (LDLT) in the Chinese population using the definition of PTDM proposed in 2003 by the World Health Organization and the American Diabetes Association. The prevalence of DM after LDLT in our study was 25% (21/84), and the incidence of PTDM was 14.9% (11/74) with 64% of cases diagnosed within 3 months after LDLT; 9.5% were observed to show impaired fasting glucose postoperatively. Multivariate analysis identified body mass index >or= 25 kg/m(2) before LDLT as the only independent risk factor for developing PTDM. Only one patient was operated for hepatitis C virus (HCV) infection. Hepatitis B virus (HBV)-related diseases were common in our study population, accounting for 78.6% of all patients. Both HCV and HBV infection status were not independent risk factors for developing PTDM. In addition, a greater tacrolimus trough blood level in the PTDM group versus no-DM group was observed at 3 months post-LDLT (11.03 ng/mL vs 4.87 ng/mL). The mean tacrolimus dose was not significantly different between the two groups. In conclusion, PTDM was prevalent among Chinese LDLT recipients.

Effects of losartan on fibrinolytic parameters and von Willebrand factor in Chinese subjects with hypertension: a comparative study versus atenolol

To compare the effects of losartan and atenolol on plasma fibrinolytic parameters and von Willebrand factor (vWF), Chinese subjects with mild-to-moderate hypertension were randomized to receive losartan (50 mg/day; n = 30) or atenolol (50 mg/day; n = 30) for 8 weeks. If target blood pressure (< 140/90 mmHg) was not achieved at week 4, hydrochlorothiazide (12.5 mg/day) was also administered. Plasma levels of tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) and vWF were determined at baseline and after treatment. Between-group baseline characteristics and blood pressure decrease were comparable. Losartan significantly reduced plasma PAI-1 and vWF and PAI-1/tPA ratio. Atenolol significantly increased plasma tPA, but PAI-1, vWF and PAI-1/tPA ratio were unchanged. In conclusion, losartan, but not atenolol improved the fibrinolytic system and reduced plasma vWF levels in Chinese hypertensives.

Preparation and analysis of 1-chloronaphthalene for highly refractive electrowetting optics

High-index oils are critical to the performance of optical electrowetting devices, such as lenses, prisms, and retroreflectors. Herein, the preparation and electrowetting analysis of 1-chloronaphthalene are reported. When 1-chloronaphthalene is mixed with small amounts of an alkane, the following properties can be achieved: refractive index > 1.60, viscosity < 5 cP for rapid switching, operation at <10 V, and +/-45 degrees of electrowetting modulation around the condition for a flat meniscus (90 degrees ).

A novel treatment strategy targeting polo-like kinase 1 in hematological malignancies

Polo-like kinase1 (PLK1) belongs to the family of serine/threonine kinases and plays an important role in centrosome maturation, bipolar spindle formation, and cytokinesis during mitosis. We found in this study that PLK1 was aberrantly highly expressed in a variety of human leukemia cell lines (n=20), as well as, freshly isolated leukemia cells from individuals with acute myelogenous leukemia (n=50) and acute lymphoblastic leukemia (n=15) compared with bone marrow mononuclear cells from healthy volunteers (n=13) (acute myelogenous leukemia, P=0.016; acute lymphoblastic leukemia, P=0.008), as measured by real-time RT-PCR. Downregulation of PLK1 by a small interfering RNA in NB4 acute myelogenous leukemia cells inhibited their proliferation. GW843682X is a novel selective PLK1 inhibitor. The compound-induced growth inhibition, caused accumulation of cells in the G2/M phase of the cell cycle and mediated apoptosis of human leukemia cells. Pre-treatment of cells with the caspase inhibitor Z-VAD-FMK attenuated the action of GW843682X in leukemia cells, indicating the involvement of the caspase pathway in the PLK1 inhibitor-mediated apoptosis. Furthermore, we found that the PLK1 inhibitor synergistically potentiated the growth inhibition and apoptosis of leukemia cells when combined with tubulin-depolymerizing agent vincristine. Taken together, targeting PLK1 may be a promising treatment strategy for individuals with leukemia.

Towards a quantitative framework for the prediction of DDIs arising from cytochrome P450 induction

Although CYP induction is not generally considered to be as clinically relevant as CYP inhibition, there are important examples where induction has caused both therapeutic failure, due to insufficient exposure to parent drug, and toxicity, mediated by increased formation of reactive metabolites. Furthermore, while there has been considerable progress in the extrapolation of in vitro data to predict the in vivo consequences of enzyme inhibition, less attention has been given to the quantitative impact of enzyme induction as a mechanism of drug-drug interaction (DDI) and as a component of compound selection and early drug development. We discuss current approaches in the context of a mechanistic framework for the prediction of the extent and time-course of enzyme induction in vivo based on in vitro experimentation. Factors influencing the extent of DDI due to CYP induction are summarised, and areas deficient in information that would allow more accurate prediction within target populations are highlighted.

The association between MIF-173 G>C polymorphism and prostate cancer in southern Chinese

BACKGROUND AND OBJECTIVES

Accumulating epidemiological and molecular evidence suggests that inflammation is an important component in the etiology of PCa. Macrophage migration inhibitory factor (MIF) plays an important role in the pro- and anti-inflammatory response to infection. This study is aimed at investigating the potential association between MIF-173 G>C polymorphism, Gleason score, clinical stage, and prostate-specific antigen (PSA) value with respect to PCa incidence among the Han nationality in Southern China.

METHODS

Genotyping was performed by using tetraprimer polymerase chain reaction (PCR) on 259 PCa patients and 301 cancer-free controls.

RESULTS

We found that the MIF-173*C variant allele was significantly associated with an increased risk of PCa [adjusted odd ratio (OR) = 2.99, 95% confident interval (CI): 1.94-4.60] and higher Gleason scores from the PCa subjects (adjusted OR = 10.72, 95% CI: 5.35-21.49). In addition, we noted that the MIF -173*C variant allele was related to higher clinical stages and PSA values in PCa patients (adjusted OR = 15.68, 95% CI: 7.40-33.23; adjusted OR = 4.37, 95% CI: 2.41-7.92, respectively).

CONCLUSION

Our data suggest that MIF-173 polymorphisms may be associated with a higher incidence of prostate cancer compared to controls, and appears to be associated with higher Gleason scores, higher clinical stages, and PSA values in those with prostate cancer.

Up-regulation of cellular FLICE-inhibitory protein in peripheral blood B lymphocytes in patients with systemic lupus erythematosus is associated with clinical characteristics

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disease which is involved in T- and B-lymphocyte-mediated autoimmunity. Apoptosis contributes to the maintenance of lymphocytes homeostasis and the deletion of autoreactive cells in SLE. Although there is evidence that cellular FLICE-inhibitory protein (c-FLIP), an antiapoptosis protein, is increased in human lupus T cells to keep them from apoptosis, but the expression of apoptosis-regulatory protein c-FLIP in SLE B lymphocytes remains unknown.

AIMS

To study the expression of c-FLIP in peripheral blood B lymphocytes in SLE patients and to investigate the relationship among the expression of c-FLIP in peripheral blood B lymphocytes in SLE patients, clinical manifestation and the levels of interleukin-4 (IL-4) and IL-10.

METHODS

In this study, we detected the expression of c-FLIP in peripheral blood B lymphocytes in SLE patients by flow cytometry and the levels of IL-4 and IL-10 in SLE serum samples by enzyme-linked immunosorbent assay and analysed their relationship with clinical characteristics.

RESULTS

We observed a significantly higher percentage of c-FLIP in peripheral B cells in SLE patients with active disease when compared to inactive ones and healthy controls. And the expression of c-FLIP in lupus peripheral B cells showed positive correlations with SLEDAI, erythrocyte sedimentation rate, C-reactive protein, antinucleosome antibody titre, IL-4, and IL-10, and negative correlation with white blood cell count. Patients with lupus nephritis had higher levels of c-FLIP in peripheral B cells than patients without lupus nephritis.

CONCLUSION

Our data show that overexpression of c-FLIP is relevant to the activity and severity of SLE. Its overexpression might play a role in preventing B cell from apoptosis in SLE. The cause of c-FLIP overexpression may be due to the increase of IL-4 and IL-10 levels in SLE patients.

Significance of phosphatase and tensin homologue (PTEN), O(6)-methylguanine-DNA methyltransferase (MGMT), and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) protein expression in gynaecomastia

This study was designed to investigate the pathogenesis of gynaecomastia by measuring phosphatase and tensin homologue (PTEN), O(6)-methylguanine-DNA methyltransferase (MGMT) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) protein in breast tissue specimens from 68 patients with gynaecomastia and 24 normal male controls using immunohistochemical staining. The gynaecomastia cases were divided into three different histological types: florid, intermediate and fibrous. The PTEN, MGMT and DNA-PKcs proteins were detected in both gynaecomastia and normal breast tissue, but the levels of immunohistochemical staining of each protein were significantly lower in gynaecomastia breast tissue than in normal breast tissue. There were also significant differences in the levels of immunohistochemical staining for the three proteins according to gynaecomastia histological type. These results suggest that abnormally low levels of PTEN, MGMT and DNA-PKcs protein in gynaecomastia breast tissue may play a role in the development of gynaecomastia. Further research is required to elucidate fully their individual roles in the pathophysiology of gynaecomastia.

SINGLE UV EXCITATION OF HOECHST 33342 AND PROPIDIUM IODIDE FOR VIABILITY ASSESSMENT OF RHESUS MONKEY SPERMATOZOA USING FLOW CYTOMETRY

Many fluorescent probes excited by visible light have been used to assess sperm quality by flow cytometry. Developing a viability evaluation method using UV excited stains would be useful for multiparameter analysis of sperm function. This investigation was conducted to determine the efficacy of Hoechst 33342 (H342) and propidium iodide (PI) dual staining for evaluating rhesus monkey sperm viability through use of flow cytometry and excited by a single UV laser. The results showed that the live cells stained only with H342 strongly correlated with expected sperm viability, and flow cytometric analyses were highly correlated with fluorescence microscopic observation. Using H342/PI/SYBR-14 triple staining method, it was found that the live/dead sperm distributions were completely concordant in both H342/PI and SYBR-14/PI assays. In addition, this dual staining was extended with fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA) to simultaneously analyze viability and acrosome integrity of sperm cryopreserved using two different extenders, TTE and TEST, and indicated that TTE offered better preservation of plasma and acrosome integrity than TEST. Therefore, the H342/PI dual staining provides an accurate technique for evaluating viability of rhesus monkey sperm and should be valuable for multiparameter flow cytometric analysis of sperm function.