RapA, a bacterial homolog of SWI2/SNF2, stimulates RNA polymerase recycling in transcription

We report that RapA, an Escherichia coli RNA polymerase (RNAP)-associated homolog of SWI2/SNF2, is capable of dramatic activation of RNA synthesis. The RapA-mediated transcriptional activation in vitro depends on supercoiled DNA and high salt concentrations, a condition that is likely to render the DNA superhelix tightly compacted. Moreover, RapA activates transcription by stimulating RNAP recycling. Mutational analyses indicate that the ATPase activity of RapA is essential for its function as a transcriptional activator, and a rapA null mutant exhibits a growth defect on nutrient plates containing high salt concentrations in vivo. Thus, RapA acts as a general transcription factor and an integral component of the transcription machinery. The mode of action of RapA in remodeling posttranscription or posttermination complexes is discussed.

KSHV vCyclin counters the senescence/G1 arrest response triggered by NF-κB hyperactivation

Many oncogenic viruses activate NF-κB as a part of their replicative cycles. We have shown recently that persistent and potentially oncogenic activation of NF-κB by the human T-lymphotropic virus 1 (HTLV-1) oncoprotein Tax immediately triggers a host senescence response mediated by cyclin-dependent kinase inhibitors: p21^CIP1/WAF1 (p21) and p27^Kip1 (p27) Here we demonstrate that RelA/NF-κB activation by Kaposi sarcoma herpesvirus (KSHV) latency protein vFLIP also leads to p21/p27 up-regulation and G1 cell cycle arrest. Remarkably, KSHV vCyclin, another latency protein co-expressed with vFLIP from a bicistronic latency-specific mRNA, was found to prevent the senescence and G1 arrest induced by HTLV-1 Tax and vFLIP respectively. This is due to the known ability of vCyclin/CDK6 complex to resist p21 and p27 inhibition and cause p27 degradation²³. In KSHV-transformed BCBL-1 cells, sustained vFLIP expression with shRNA-mediated vCyclin depletion resulted in G1 arrest. The functional interdependence of vFLIP and vCyclin explains why they are co-translated from the same viral mRNA. Importantly, deregulation of the G1 cyclin-dependent kinase can facilitate chronic IKK/NF-κB activation.

Albiglutide does not impair the counter-regulatory hormone response to hypoglycaemia: a randomized, double-blind, placebo-controlled, stepped glucose clamp study in subjects with type 2 diabetes mellitus

AIM

To determine if the glucagon-like peptide-1 (GLP-1) receptor agonist albiglutide, once weekly, impairs counter-regulatory responses during hypoglycaemia.

METHODS

We conducted a randomized, double-blind, parallel, placebo-controlled study in subjects with type 2 diabetes mellitus. A single dose of albiglutide 50 mg (n = 22) or placebo (n = 22) was administered on day 1. Glucose was clamped on day 4 (to coincide with the approximate albiglutide maximum plasma concentration) at 9.0, 5.0, 4.0, 3.3 and 2.8 mmol/l (162, 90, 72, 59.4 and 50.4 mg/dl), with a post-clamp recovery period to 3.9 mmol/l (70 mg/dl). Hormone measurements were made at each plateau and adverse events (AEs) were recorded.

RESULTS

The counter-regulatory hormones glucagon, epinephrine, norepinephrine, growth hormone and cortisol were appropriately suppressed when plasma glucose levels were >4.0 mmol/l (>72 mg/dl), but increased in the albiglutide and placebo groups with glucose levels <3.3 mmol/l (<59.4 mg/dl) in response to hypoglycaemia. The area under the curve geometric mean ratios (albiglutide : placebo), calculated from the clamped plateau of 4.0 mmol/l (72 mg/dl) to the glucose recovery point, were not significantly different for any of the counter-regulatory hormones. When plasma glucose levels were >5.0 mmol/l (>90 mg/dl), albiglutide increased pancreatic β-cell secretion of C-peptide in a glucose-dependent manner to a greater extent than did placebo, and it was suppressed in each group when levels were <4.0 mmol/l (<72 mg/dl). No significant difference between groups was observed in the recovery time to glucose level ≥3.9 mmol/l (≥70 mg/dl). There were no clinically relevant differences in AEs or other safety variables.

CONCLUSIONS

A single 50-mg dose of albiglutide was well tolerated and did not impair the counter-regulatory response to hypoglycaemia. These data provide mechanistic evidence supporting the low intrinsic hypoglycaemic potential of albiglutide.

SmgGDS is up-regulated in prostate carcinoma and promotes tumour phenotypes in prostate cancer cells

SmgGDS is a guanine nucleotide exchange factor with the unique ability to activate multiple small GTPases, implicating it in cancer development and progression. Here, we investigated the role of SmgGDS in prostate cancer by studying the expression of SmgGDS in benign and malignant prostatic tissues. We also probed SmgGDS function in three prostate carcinoma cell lines using small interfering RNA (siRNA). Immunohistochemical analysis revealed that SmgGDS levels were elevated in prostatic intraepithelial neoplasia (PIN), prostate carcinoma, and metastatic prostate carcinoma. In addition, expression of SmgGDS positively correlated with that of cyclooxygenase-2 (COX-2), a protein believed to promote the development of prostate carcinoma. Reduction of SmgGDS expression in prostate carcinoma cells inhibited proliferation and migration, irrespective of androgen receptor status. These effects were accompanied by a reduction in COX-2 expression and in activity of NF-kappaB, a known regulator of COX-2. Taken together, these findings suggest that SmgGDS promotes the development and progression of prostate cancer, possibly associated with NF-kappaB-dependent up-regulation of COX-2.

n-Butanol soluble fraction of the water extract of Chinese toon fruit ameliorated focal brain ischemic insult in rats via inhibition of oxidative stress and inflammation

AIM OF THE STUDY

Toona sinensis Roem. (Meliaceae; Toona sinensis; Chinese toon) is a type of arbor that is widely distributed in Asia. The fruits of Toona sinensis Roem has been traditionally recognized for treatment of cerebrovascular diseases. To evaluate the potential clinical use of the fruits of Toona sinensis Roem, we determined the dose dependence of the neuroprotective efficacy in a focal cerebral ischemic reperfusion model of rats and explored the underlying mechanisms.

MATERIALS AND METHODS

Rats were subjected to occlusion of the middle cerebral artery (MCAO) by a nylon filament and treated with different doses (20mg/kg and 30 mg/kg) of n-butanol soluble fraction of the water extract of Chinese toon fruit or the vehicle for 1 week before induction of ischemia, s.i.d..

RESULTS

n-Butanol soluble fraction of the water extract of Chinese toon fruit reduced in a dose-dependent manner the ischemia-induced cerebral infarct and edema volume and attenuated neurological deficits observed at 6h point after ischemia. n-Butanol soluble fraction of the water extract of Chinese toon fruit reduced the levels of nitrate, nitrite, lipid peroxidation, cyclooxygenase-1, thromboxane in post-ischemic brain. n-Butanol soluble fraction of the water extract of Chinese toon fruit adjusted the elevation of the activity of glutathione peroxidase and superoxide dismutase in ischemic brain.

CONCLUSIONS

The present study was the first evidence of effectiveness of n-butanol soluble fraction of the water extract of Chinese toon fruit in the rat stroke models, as it reduced infarct volume, inhibited the oxidative stress and inflammation.

Human T cell leukaemia virus type 2 tax protein mediates CC-chemokine expression in peripheral blood mononuclear cells via the nuclear factor kappa B canonical pathway

Retroviral co-infections with human immunodeficiency virus type-1 (HIV-1) and human T cell leukaemia virus type 1 (HTLV-1) or type 2 (HTLV-2) are prevalent in many areas worldwide. It has been observed that HIV-1/HTLV-2 co-infections are associated with slower rates of CD4(+) T cell decline and delayed progression to AIDS. This immunological benefit has been linked to the ability of Tax2, the transcriptional activating protein of HTLV-2, to induce the expression of macrophage inflammatory protein (MIP)-1α/CCL3, MIP-1β/CCL4 and regulated upon activation normal T cell expressed and secreted (RANTES)/CCL5 and to down-regulate the expression of the CCR5 co-receptor in peripheral blood mononuclear cells (PBMCs). This study aimed to assess the role of Tax2-mediated activation of the nuclear factor kappa B (NF-κB) signalling pathway on the production of the anti-viral CC-chemokines MIP-1α, MIP-1β and RANTES. Recombinant Tax1 and Tax2 proteins, or proteins expressed via adenoviral vectors used to infect cells, were tested for their ability to activate the NF-κB pathway in cultured PBMCs in the presence or absence of NF-κB pathway inhibitors. Results showed a significant release of MIP-1α, MIP-1β and RANTES by PBMCs after the activation of p65/RelA and p50. The secretion of these CC-chemokines was significantly reduced (P < 0·05) by canonical NF-κB signalling inhibitors. In conclusion, Tax2 protein may promote innate anti-viral immune responses through the activation of the canonical NF-κB pathway.

[Esophago-gastric mucosal anastomosis with staples after resection of cancer of the esophagus and gastric cardia]

OBJECTIVE

To delve an effective method to prevent anastomotic leakage and stenosis.

METHODS

Staples were used to carry out mucosal anastomosis between the esophagus and stomach.

RESULTS

Four hundred thirty four patients were so treated. The morbidity rate was 9.3% and the mortality rate was 1.4%. No leakage or stenosis was found in this series.

CONCLUSION

Using staples to perfonm mucosal anastomotis has the advantages of being simple and safe. Besides prevention of leakage and stenosis, sufficient length of resection of the esophagus helps reduce the likelihood of residual stump cancer recurrence.

[Incidence and risk factors of delirium in patients post permanent pacemaker implantation]

OBJECTIVE

To evaluate the incidence and risk factors of postoperative delirium in patients post permanent pacemaker implantation.

METHODS

Patients underwent permanent pacemaker implantation in our department from September 2013 to February 2015 were included in this study. Delirium was measured by the confusion assessment method on the first three postoperative days. All the patients were divided into the postoperative delirium group and the non-delirium control group according to whether new onset delirium was diagnosed. Risk factors significantly associated with postoperative delirium detected by univariate analysis were entered into multivariable analysis to define the independent predictors of postoperative delirium.

RESULTS

A total of 225 patients were enrolled in this study. The incidence of postoperative delirium was 5.3%. Patients developing postoperative delirium were older ((83±5) years vs. (74±11) years, P=0.002), had a significantly higher incidence of blood pressure fluctuations (58.3% (7/12) vs. 4.7% (10/213), P<0.001), hyponatremia (25.0% (3/12) vs. 5.2% (11/213), P=0.030) and had higher systolic blood pressure ((157±35) mmHg vs. (136±22)mmHg, 1 mmHg=0.133 kPa, P=0.007). However, patients developing postoperative delirium had lower preoperative average heart rate ( (47±18)bpm vs. (58±15)bpm, P=0.007). Multiple regression analysis showed that advanced age (OR= 2.984, 95% CI: 1.226-7.624, P=0.016) and blood pressure fluctuations (OR=27.393, 95% CI: 6.735-111.417, P<0.001) are the independent risk factors for pacemaker patients with postoperative delirium.

CONCLUSION

Advanced age and blood pressure fluctuations are independent risk factors of postoperative delirium in patients post permanent pacemaker implantation.

[Developmental effects of TCIPP and TnBP on zebrafish (Danio rerio) embryos]

Objective: To investigate the toxicity of tris (2-chloropropyl) phosphate (TCIPP) and tributyl phosphate (TnBP) on the growth and development of zebrafish embryos, as well as to explore the underlying mechanisms at the transcriptional level. Methods: With zebrafish as a model, two hpf zebrafish embryos were exposed to TCIPP and TnBP (0.1, 1, 10, 100, 500, and 1 000 μmol/L) using the semi-static method, and their rates of lethality and hatchability were determined. The transcriptome changes of 120 hpf juvenile zebrafish exposed to environmentally relevant concentrations of 0.1 and 1 μmol/L were measured. Results: The 50% lethal concentrations (LC₅₀) of TCIPP and TnBP for zebrafish embryos were 155.30 and 27.62 μmol/L (96 hpf), 156.5 and 26.05 μmol/L (120 hpf), respectively. The 72 hpf hatching rates of TCIPP (100 μmol/L) and TnBP (10 μmol/L) were (23.33±7.72)% and (91.67±2.97)%, which were significantly decreased compared with the control group (P<0.05). Transcriptome analysis showed that TnBP had more differential genes (DEGs) than TCIPP, with a dose-response relationship. These DEGs were enriched in 32 pathways in total, including those involved in oxidative stress, energy metabolism, lipid metabolism, and nuclear receptor-related pathways, using the IPA pathway analysis. Among them, three enriched pathways overlapped between TCIPP and TnBP, including TR/RXR activation and CAR/RXR activation. Additionally, DEGs were also mapped onto pathways of LXR/RXR activation and oxidative stress for TnBP exposure only. Conclusion: Both TCIPP and TnBP have growth and developmental toxicities in zebrafish embryos, with distinct biomolecular mechanisms, and TnBP has a stronger effect than TCIPP.

[Polymorphism of HLA-DRB1, DQB1 in the Hans of north China]

OBJECTIVE

To understand polymorphism of HLA-DRB1, DQB1 in the Hans of north China and obtain more comprehensive and accurate data on genetics at DNA level.

METHODS

Polymerase chain reaction-sequence specific primers (PCR-SSP) were used to determine HLA-DRB1, DQB1 alleles in 107 unrelated healthy Han individuals of north China.

RESULTS

The authors determined 14 DRB1, 9 DQB1 alleles, which included not only the allele frequencies that corresponded to the gene frequencies of DR, DQ loci determined by other 9 cooperating labs but also the allele frequencies of DRB1*15, DRB1*16, DQB1*0301, DQB1*0302, DQB1*0303, DQB1*05, DQB1*0601, DQB1*0602, and DQB1*0604 that other serology labs did not report.

CONCLUSION

This study has obtained a more comprehensive and accurate data set of the normal allele frequencies and linkage disequilibrium parameters of HLA-DRB1, DQB1 in the Hans of north China, which may be of significance in the studies on population genetics and disease association.

[The recombinant vaccinia viruses expressing HPV type 16 wild or mutant E7 protein elicit immunity against tumor cells in mice]

OBJECTIVE

To select mutants of HPV 16 E7 suitable for vaccine development.

METHODS

Several recombinant vaccinia viruses (VwE7, VmE7-1, and VmE7-2) expressing wild E7 or its mutants, ME7-1 (24G26G) and ME7-2 (24G26G91G) respectively, were employed to study their antigenicity and anti tumor activity.

RESULTS

Both VmE7-1 and VwE7 could elicit cytotoxic T lymphocytes (CTL)and protect mice against tumor cells challenge, but VmE7-2 could not induce the immune reactions compared with VmE7-1 and VwE7.

CONCLUSIONS

It suggested that ME7-1 could be used to develop a therapeutic vaccine for cervical cancer.