Rapid and visual detection of dengue virus using recombinase polymerase amplification method combined with lateral flow dipstick.

Dengue virus (DENV), a member of the genus Flavivirus within the family Flaviviridae, is one of the most significant mosquito-borne viruses that causing dengue fever in human. A rapid diagnostic would be helpful to detect DENV infection in a timely manner. In the last decade, recombinase polymerase amplification (RPA) technique has been experiencing rapid development and widely employed to detect various other pathogens. In present study, a reverse transcription RPA (RT-RPA) assay combined with lateral flow dipstick (LFD) was established for rapid detection of DENV. The assay could detect DENV-1, -2, -3 and -4. The minimal detection limit of the RT-RPA-LFD assay was 10 copies RNA molecules. The assay was DENV-specific since it had no non-specific reactions with other common human pathogens. The clinical performance of the RT-RPA assay was validated using 120 clinical samples. The coincidence rate between RT-RPA-LFD and qRT-PCR for the clinical samples was 100%, indicating the RT-RPA-LFD assay had good diagnostic performance on clinical samples. The RT-RPA-LFD assay required no sophisticated instrument, providing a possible solution for DENV diagnosis in recourse-limited settings where DENV infection is epidemic.

Development of a reverse transcription recombinase polymerase amplification assay for rapid detection of human respiratory syncytial virus.

Respiratory syncytial virus (RSV) is one of the most important causative agents that causing respiratory tract infection in children and associated with high morbidity and mortality. A diagnostic method would be a robust tool for identification of RSV infection, especially in the resource-limited settings. Recombinase polymerase amplification (RPA) is a novel isothermal amplification technique which has been widely employed to detect human/animal pathogens. In present study, a probe-based reverse transcription RPA (RT-RPA) assay was established for the detection of RSV. The primers and probe were designed based on the sequences of the conserved nucleocapsid (N) gene. The minimal detection limit of the RT-RPA assay for the detection of RSV B was 19 copies of RNA molecules at 95% probability, whereas the detection limit for RSV A was 104 copies molecule. The assay was RSV-specific since it had no non-specific reactions with other common human pathogens. The clinical performance of the RT-RPA assay was validated using 188 nasopharyngeal aspirates (NPAs). The nucleic acid extraction of the samples was performed by use of the magnetic bead-based kit which didn't require the heavy and expensive centrifuge. The coincidence rates between RT-RPA and qRT-PCR for the clinical samples was 96%, indicating the RT-RPA assay had good diagnostic performance on clinical samples. The real-time RT-RPA assay combined with the manual genome extraction method make it potential to detect clinical samples in field, providing a possible solution for RSV diagnosis in remote rural areas in developing countries.

Brain astrocytoma misdiagnosed as anti-NMDAR encephalitis: a case report.

BACKGROUND: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, which is the most common type of autoimmune encephalitis, is caused by the production of autoantibodies against NMDA receptor. Anti-NMDAR encephalitis patients present with various non-specific symptoms, such as abnormal psychiatric or behaviour, speech dysfunction, cognitive dysfunction, seizures, movement disorders, decreased level of consciousness, and central hypoventilation or autonomic dysfunction. CASE PRESENTATION: A 67-year-old man presented with new-onset focal seizures. The brain magnetic resonance imaging (MRI) plain scan and enhanced scan showed abnormal signal on the proximal midline frontoparietal junction region. Anti-NMDAR antibody was detected in cerebrospinal fluid (CSF) and serum using a commercial kit (Euroimmune, Germany) by indirect immunofluorescence testing (IIFT) according to the manufacturer's instructions for twice. Both of the test results were positive in CSF and serum. The patient was diagnosed as anti-NMDAR encephalitis and then was treated repeatedly with large dose of intravenous corticosteroids and gamma globulin. Accordingly, the refractory nature of seizures in this case may be attributed to NMDAR autoantibodies. When the patient presented at the hospital for the third time, the brain MRI revealed an increase in the size of the frontal parietal lesion and one new lesion in the left basal ganglia. The patient underwent a surgical biopsy and astrocytoma was confirmed by histopathology. CONCLUSIONS: Although the sensitivity and specificity of anti-NMDAR-IgG antibodies in CSF to diagnose anti-NMDAR encephalitis are close to 100%, it is not absolute. Anti-NMDAR antibodies were positive, which might make the diagnosis more complex. The diagnosis of atypical presentation of anti-NMDAR encephalitis requires reasonable exclusion of other disorders.

Detection methanogens in newly settled sediments from Xuanwu Lake in Nanjing, China.

Sediments from Xuanwu Lake have been dredged in the past 3 years to improve the water quality, but methanogenesis should still exist in the newly settled sediment. Methane production, methanogens, and physiochemical parameters were detected in the surface sediments (0-5 cm) and/or vertical sediments (0-21 cm, segmented at interval of 3 cm). Methane flux at water-air interface varied among five detected sites. Principal component analysis showed that CH(4) flux, content of water and the concentration of total nitrogen (TN), CH(4) and organic matters (OM) weighed most heavily on the component I in surface sediments while different patterns were observed for vertical sediments. The copy number of the 16S rRNA gene for bacteria was lower in the surface sediment (0-6 cm) than that in deeper sediments (12-21 cm), while 16S rRNA genes of Archaea were almost evenly distributed in the vertical sediments. Representatives belonging to the orders Methanobacteriales, Methanomicrobiales, and Methanosarcinales were detected in all samples of the vertical sediments, except that no members of the Methanococcales were detected in the samples at 0-6 cm. The level of Methanobacteriales reached a highest density at 18.1 × 10(4) copies g(-1) dry weight (dw) at 6-9 cm; for Methanosarcinales (76.89 × 10(6) copies g(-1) dw) and Methanococcales (82.70 × 10(3) copies g(-1) dw) at 12-15 cm, whereas for Methanomicrobiales (43.37 × 10(6) copies g(-1) dw) at 9-12 cm. Methanosarcinaceae and Methanosaetaceae reached to their highest densities at 6-9 and 9-12 cm, respectively. These data provided useful information for better understanding the methanogenesis in the newly settled sediments of a recently dredged lake.

[The relationship between carboxylesterase 1 gene polymorphisms and susceptibility to antituberculosis drug-induced hepatotoxicity].

OBJECTIVE: To study the relationship between the genetic polymorphisms of carboxylesterase 1 gene (CES1) and the susceptibility to antituberculosis drug-induced hepatotoxicity (ATBDIH). METHODS: Genetic polymorphisms of CES1 in 473 tuberculosis patients with or without hepatotoxicity (200:273) after antituberculosis chemotherapy were analyzed by PCR-MassArray. RESULTS: In 4 tags of CES1 single nucleotide polymorphism (SNP), the frequency of the rs1968753 allele had statistical difference between the hepatotoxicity group and the no-hepatotoxicity group(P = 0.0236). The characteristics of anti-hepatotoxicity had been shown relationship with rs8192950 (P = 0.044, OR = 0.649, 95%CI = 0.426 - 0.989, AC/AA) and rs1968753 (P = 0.048, OR = 0.556, 95%CI = 0.311 - 0.995, GG/AA). The diplotypes with 'CGC' haplotype exhibited significant protection against hepatotoxicity at one copy (P = 0.048, OR = 0.654, 95%CI = 0.430 - 0.996). CONCLUSIONS: The genetic polymorphisms of CES1 might have significant association with ATBDIH. SNP rs8192950 AC genotype and rs1968753 GG genotype might be the candidates for risk prediction of ATBDIH.

Mannose-binding lectin 2 gene polymorphisms and their association with tuberculosis in a Chinese population.

BACKGROUND: Immune- and inflammation-related genes (IIRGs) play an important role in the pathogenesis of tuberculosis (TB). However, the relationship between IIRG polymorphisms and TB risk remains unknown. In this study, the gene polymorphisms and their association with tuberculosis were determined in a Chinese population. METHODS: We performed a case-control study involving 1016 patients with TB and 507 healthy controls of Han Chinese origin. Sixty-four single-nucleotide polymorphisms (SNPs) belonging to 18 IIRGs were genotyped by the PCR-MassArray assay, and the obtained data was analyzed with χ2-test, Bonferroni correction, and unconditional logistic regression analysis. RESULTS: We observed significant differences in the allele frequency of LTA rs2229094*C (P = 0.015), MBL2 rs2099902*C (P = 0.001), MBL2 rs930507*G (P = 0.004), MBL2 rs10824793*G (P = 0.004), and IL12RB1 rs2305740*G (P = 0.040) between the TB and healthy groups. Increased TB risk was identified in the rs930507 G/G genotype (Padjusted = 0.027) under a codominant genetic model as well as in the rs2099902 (C/T + C/C) vs T/T genotype (Padjusted = 0.020), rs930507 (C/G + G/G) vs C/C genotype (Padjusted = 0.027), and rs10824793 (G/A + G/G) vs A/A genotype (Padjusted = 0.017) under a dominant genetic model after Bonferroni correction in the analysis of the overall TB group rather than the TB subgroups. Furthermore, the rs10824793_rs7916582*GT and rs10824793_rs7916582*GC haplotypes were significantly associated with increased TB risk (P = 0.001, odds ratio [OR] = 1.421, 95% confidence interval [CI]: 1.152-1.753; and P = 0.018, OR = 1.364, 95% CI: 1.055-1.765, respectively). Moreover, the rs10824793_rs7916582*AT/AT or rs10824793_rs7916582*GT/GT diplotype showed a protective (P = 0.003, OR = 0.530, 95% CI: 0.349-0.805) or harmful (P = 0.009, OR = 1.396, 95% CI: 1.087-1.793) effect against the development of TB. CONCLUSIONS: This study indicated that MBL2 polymorphisms, haplotypes, and diplotypes were associated with TB susceptibility in the Han Chinese population. Additionally, larger sample size studies are needed to further confirm these findings in the future.

Neuroprotective effect of angiotensin-(1-7) against rotenone-induced oxidative damage in CATH.a neurons.

There is evidence to support that ROSs are increased in Parkinson's disease (PD). Our recent research showed that angiotensin II (Ang II) participated in the pathogenesis of PD by triggering oxidative stress. Angiotensin-(1-7)[Ang-(1-7)] has been shown to moderate the adverse effects of the Ang II in many diseases. The purpose of the present study was to determine whether the Ang-(1-7) could have similar effects in CATH.a neurons. We used rotenone-induced neuron injury models to evaluate changes in cultured CATH.a cell lines levels of SOD, GSH and ROS. We also evaluated the expression of AT1, AT2, Mas receptors and Nox1, Nox2, P47phox, Hsp70 in treated with PBS, rotenone, Ang-(1-7), or Mas receptor antagonist A-779, alone and combined. The qRT-PCR and western blot were used to detect mRNA and protein levels of the AT1, AT2, Mas receptors and Nox1, Nox2, P47phox, Hsp70. The levels of SOD and GSH were determined by using commercial kits. The ROS generation was measured by the fluorescent probe assay. Ang-(1-7) in our current study significantly decreased rotenone-induced oxidative damage and increased the SOD and GSH generation. In addition, Ang-(1-7) significantly elevated Mas receptor expression and reduced NADPH oxidase activation, and these effects were completely eliminated by the A-779. Our findings suggest that Ang-(1-7) attenuates rotenone-induced oxidative damage in CATH.a neurons by activating the Mas receptor expression and inhibiting NADPH oxidase.

[Rhizospheria bacteria of Poplus euphratica improve resistance of wood plants to heavy metals].

Populus euphratica is a special kind of woody plant, which lives in desert area of northwestern China and is strongly resistant to multiple abiotic stresses. However, the knowledge about the ecology and physiological roles of microbes associated with P. euphratica is still not enough. In this paper, we isolated 72 strains resistant to heavy metals from rhizospheric soil of wild P. euphratica forest in Shaya County of Xinjiang. There were 50 strains conveying resistance to one of four heavy metals (Cu2+, Ni2+, Pb2+ or Zn2+), and 9 strains were resistant to at least three kinds of these heavy metals. Five of the multi-heavy metal resistant bacteria were inoculated to bamboo willow and the growth inhibition of plant under stresses of Cu2+ or Zn2+ was found to be alleviated to different extent. Among the 5 strains, Pseudomonas sp. Z30 and Cupriavidus sp. N8 significantly improved the growth of plant under stresses of both zinc and copper when compared to the uninoculated controls. The results showed the diversity of heavy metal resistant bacteria associated with P. euphratica which lived in a non-heavy metal polluted area and some of the multi-heavy metal resistant bacteria may greatly improve the growth of host plant under heavy metal.stress. The PGPB associated with P. euphratica has potential application in the xylophyte-microbe remediation of environmental heavy metal pollution.

Angiotensin II does not directly affect Aß secretion or ß-/γ-secretase activity via activation of angiotensin II type 1 receptor.

Recent studies suggest that brain angiotensin II (Ang II), the major effector molecule of the renin-angiotensin system, is implicated in the pathogenesis of Alzheimer's disease (AD). However, it remains unknown whether activation or blockade of the angiotensin II type 1 receptor (AT1R) has an impact on the secretion of amyloid-ß (Aß), the key molecule in the pathogenesis of AD. In this study, the cell models cultured primary hippocampal neurons and human embryonic kidney 293 cells, were transfected with AT1R and amyloid precursor protein/presenilin-1 (PS1). The effects of activation/blockade of the AT1R on Aß secretion, PS1 level and ß-/γ-secretase activity were investigated in different cells. When AT1R was stimulated with Ang II at concentrations from 10nM to 1000nM, only a tendency toward increased Aß secretion and ß-/γ-secretase activity was noticed in cultured primary hippocampal neurons. However, no significant change in soluble Aß(40) or Aß(42), the level of PS1, or secretase activity was found in the cells. Similarly, when the AT1R was blocked by losartan, no significant alteration of Aß secretion, PS1 levels or secretase activity was detected. In conclusion, this in vitro study demonstrates that Ang II does not directly affect Aß secretion or secretase activity via activation of AT1R. This study is significantly meaningful for exploring the pharmacologic mechanisms of angiotensin II receptor blockers in AD.