Molecular mechanisms of azole resistance in Candida tropicalis isolates causing invasive candidiasis in China

OBJECTIVE

We investigated molecular mechanisms responsible for azole resistance in Candida tropicalis isolates.

METHODS

We studied 507 C. tropicalis isolates causing invasive candidiasis from ten hospitals over 5 years. Antifungal susceptibility was determined by broth microdilution methods. Point mutations in the C. tropicalis ERG11 gene that may confer azole resistance were explored and verified. The expression levels of ERG11, CYTb, MDR1 and CDR1 genes were compared in 20 fluconazole-susceptible and 20 fluconazole-resistant isolates.

RESULTS

Fluconazole-susceptible, -susceptible dose-dependent and -resistant strains accounted for 76.7% (389/507), 10.5% (53/507) and 12.8% (65/507) of C. tropicalis isolates, respectively. The ERG11 mutation A395T/W occurred in 10.7% (54/507) of isolates, all of which were resistant to fluconazole. The nucleotide mutation C461T/Y was the second most common (50/507 isolates, 9.9%), and all isolates carrying C461T/Y also had the mutation A395T/W. However, the presence of C461T did not contribute to the azole-resistant phenotype. Substitutions V125A, Y257H and G464S (<2% of isolates), which were reported for the first time in C. tropicalis, also conferred fluconazole non-susceptible phenotypes. Compared with fluconazole susceptible isolates, fluconazole-resistant isolates had higher ERG11 (fold expression level 1.42 versus 0.79, p < 0.01) but lower CYTb (fold expression level 1.26 versus 2.67, p < 0.01) gene expression levels. Three azole-resistant isolates carrying the wild-type ERG11 gene had higher levels of CDR1 and MDR1 expression.

CONCLUSIONS

ERG11 missense mutations were the major mechanism responsible for azole resistance in C. tropicalis isolates, but overexpression of ERG11, CDR1 and MDR1, as well as reduced expression of CYTb, also contributed to resistance.

Sustained pain hypersensitivity in the stressed colon: Role of mast cell-derived nerve growth factor-mediated enteric synaptic plasticity

BACKGROUND

Sustained pain hypersensitivity is the hallmark of stressed colon which could be partially explained by central sensitization with synaptic plasticity, the key mechanism of memory. We previously identified that synaptic plasticity of enteric nerve system (ENS) contributed to peripheral pain maintaining in the gut. However, the mechanisms of enteric "memory" formation remain elusive.

METHODS

In this study, rats were exposed to water avoidance stress (WAS) or sham stress (SS), with cromolyn sodium or physiological saline injected intraperitoneally 30 minutes before stress every day. The abdominal withdrawal reflex scores, mesenteric afferent nerve activity, enteric neural c-fos expression, and enteric synaptic plasticity were assessed, and mast cell infiltration and degranulation. Furthermore, colonic mucosal mediators-induced enteric synaptic plasticity and the role of mast cell-derived nerve growth factor (NGF), tryptase, and histamine were investigated via ex vivo longitudinal muscle-myenteric plexus (LMMP) organotypic culture.

KEY RESULTS

It is shown that mast cell stabilizing inhibited WAS-induced visceral hypersensitivity through enhancing visceral pain threshold, decreasing spontaneous and distention-induced mesenteric afferent firing, and downregulating enteric neural activation (c-fos). Importantly, WAS led to evident enteric synaptic plasticity, but decreased by cromolyn. Water avoidance stress-derived mucosal supernatants markedly enhanced the c-fos expression and enteric synaptic plasticity in LMMP tissues, which could be eliminated by mast cell inhibition or NGF neutralization, but not tryptase or histamine blocking.

CONCLUSIONS & INFERENCES

In conclusion, mast cells/NGF pathway may be the key regulator of synaptic plasticity of ENS and participate in the formation of chronic stress-induced sustained visceral hypersensitivity.

Analysis of (CAG)n expansion in ATXN1, ATXN2 and ATXN3 in Chinese patients with multiple system atrophy

Multiple system atrophy (MSA) is a complex and multifactorial neurodegenerative disease, and its pathogenesis remains uncertain. Patients with MSA or spinocerebellar ataxia (SCA) show overlapping clinical phenotypes. Previous studies have reported that intermediate or long CAG expansions in SCA genes have been associated with other neurodegenerative disease. In this study, we screened for the number of CAG repeats in ATXN1, 2 and 3 in 200 patients with MSA and 314 healthy controls to evaluate possible associations between (CAG)_n in these three polyQ-related genes and MSA. Our findings indicated that longer repeat lengths in ATXN2 were associated with increased risk for MSA in Chinese individuals. No relationship was observed between CAG repeat length in the three examined genes and age at onset (AO) of MSA.

p16 gene expression in pancreatic cancer tissue and its importance in diagnosis

The aim of this study was to assess the importance of p16 gene expressions in pancreatic cancer tissue for early diagnosis and treatment. Two groups were included in the study: an experimental group of 35 pancreatic cancer tissue specimens and a control group of 35 pancreatic cancer adjacent tissues collected during surgery. The expression of p16 gene in the two groups was observed using the immunohistochemical streptavidin peroxidase conjugated (S-P) method. The results were statistically interpreted using SPSS22.0 software. The positive expression rate of p16 in the experimental group was lower than that of the control group (p less than 0.05). Comparing the intensity of p16 gene expression, differentiation degree, clinical stage and metastases of nearby lymph nodes the differences had statistical significance (p less than 0.05). The intensity of p16 gene expression in high and medium differentiated pancreatic cancer group was higher than that of the low differentiated group. p16 gene expression in stages III and IV groups was lower than that in stages I and II groups. Differentiation degree, clinical stage, metastases of nearby lymph nodes and distant metastasss were negatively related with p16 gene expression (p less than 0.05). There was no correlation between age or gender and p16 gene expression. The decreased expression of p16 gene in pancreatic cancer tissue was negatively correlated with differentiation degree and clinical stage. Our results indicated that p16 can be used as a cue signal for diagnosing advanced pancreatic cancer.

Association of adiposity indices with bone density and bone turnover in the Chinese population

Associations of adiposity indices with bone mineral density (BMD) and bone turnover markers were evaluated in Chinese participants. Body mass index, fat mass, and lean mass are positively related to BMD in both genders. Subcutaneous fat area was proved to be negatively associated with BMD and positively correlated with osteocalcin in postmenopausal females.

INTRODUCTION

Obesity is highly associated with osteoporosis, but the effect of adipose tissue on bone is contradictory. Our study aimed to assess the associations of adiposity indices with bone mineral density (BMD) and bone turnover markers (BTMs) in the Chinese population.

METHODS

Our study recruited 5215 participants from the Shanghai area, evaluated related anthropometric and biochemical traits in all participants, tested serum BTMs, calculated fat distribution using magnetic resonance imaging (MRI) images and image analysis software, and tested BMD with dual-energy X-ray absorptiometry.

RESULTS

When controlled for age, all adiposity indices were positively correlated with BMD of all sites for both genders. As for the stepwise regression analysis, body mass index (BMI), fat mass, and lean mass were protective for BMD in both genders. However, subcutaneous fat area (SFA) was detrimental for BMD of the L1-4 and femoral neck (β ± SE -0.0742 ± 0.0174; p = 2.11E-05; β ± SE -0.0612 ± 0.0147; p = 3.07E-05). Adiposity indices showed a negative correlation with BTMs adjusting for age, especially with osteocalcin. In the stepwise regression analysis, fat mass was negatively correlated with osteocalcin (β ± SE -8.8712 ± 1.4902; p = 4.17E-09) and lean mass showed a negative correlation with N-terminal procollagen of type I collagen (PINP) for males (β ± SE -0.3169 ± 0.0917; p = 0.0006). In females, BMI and visceral fat area (VFA) were all negatively associated with osteocalcin (β ± SE -0.4423 ± 0.0663; p = 2.85E-11; β ± SE -7.1982 ± 1.1094; p = 9.95E-11), while SFA showed a positive correlation with osteocalcin (β ± SE: 5.5993 ± 1.1753; p = 1.98E-06).

CONCLUSION

BMI, fat mass, and lean mass are proved to be beneficial for BMD in both males and postmenopausal females. SFA is negatively associated with BMD and positively correlated with osteocalcin in postmenopausal females.

Aerobic exercise blocks interleukin-6 levels and germ cell apoptosis in obese rats

To investigate the effect of a high-fat diet and aerobic exercise intervention and its related mechanism on rat germ cell apoptosis. Forty male Sprague-Dawley rats were randomly divided into control group, high-fat diet group, control exercise group and high-fat exercise group. Rats were fed with high-fat diet or were given weight-free swimming. The levels of TG, TC, HDL, LDL and IL-6 in serum of rats were measured. The body weight, body length and inguinal fat weight were measured to calculate the Lee's index and lipid/body weight ratio. The expression of IL-6 mRNA in inguinal fat and IL-6R,Bcl-2 and Bax mRNA in testis was detected by RT-PCR. The morphological structure of testis was observed, and the Johnsen's ten-point score was calculated by HE staining, and the germ cell apoptosis was detected by TUNEL method. We got from the experimental results: a high-fat diet induces obesity and lipid metabolism disorder, alters testis morphological structure and increases germ cell apoptosis in rats. Aerobic exercise improves the lipid metabolism disorder and interferes with germ cell apoptosis by reducing interleukin-6 and interleukin-6 receptor expression.

Enzymatic production of sterculic acid from the novel Phoenix tree seed oil: Optimization and kinetic study

Phoenix tree (Firmiana simplex) seed oil is a novel oil which is rich in sterculic acid. Sterculic acid, a cyclopropene fatty acid, can be used as the inhibitor of the stearoyl-CoA desaturase system and mammary carcinomas growth. In this work, Lipozyme TLIM-catalyzed hydrolysis of the novel Phoenix tree seed oil was used to prepare sterculic acid. High temperature GC-FID and the degree of hydrolysis (DH) were used to monitor the reaction progress. Effects of reaction variables on the hydrolysis were evaluated and optimized using response surface methodology. Results showed that sterculic acid can be successfully prepared from the novel seed oil, and the effect of reaction variables on the hydrolysis decreased in the order of reaction time > enzyme load > temperature. A high yield of fatty acids (DH, 98.2±0.8%) can be obtained under optimized conditions (45 ºC, mass ratio of water to oil 10:1, enzyme load 10%, and 18 h). The Arrhenius equation for the hydrolysis was LnV0 = 9.12-4721/T. The activation energy was 39.25KJ/mol. The kinetic values for Vmax, K/m were 0.232mol/(L∙min) and 0.084 mol/L, respectively.

Diurnal variations and source apportionment of ozone at the summit of Mount Huang, a rural site in Eastern China

Comprehensive measurements were conducted at the summit of Mount (Mt.) Huang, a rural site located in eastern China during the summer of 2011. They observed that ozone showed pronounced diurnal variations with high concentrations at night and low values during daytime. The Weather Research and Forecasting with Chemistry (WRF-Chem) model was applied to simulate the ozone concentrations at Mt. Huang in June 2011. With processes analysis and online ozone tagging method we coupled into the model system, the causes of this diurnal pattern and the contributions from different source regions were investigated. Our results showed that boundary layer diurnal cycle played an important role in driving the ozone diurnal variation. Further analysis showed that the negative contribution of vertical mixing was significant, resulting in the ozone decrease during the daytime. In contrast, ozone increased at night owing to the significant positive contribution of advection. This shifting of major factor between vertical mixing and advection formed this diurnal variation. Ozone source apportionment results indicated that approximately half was provided by inflow effect of ozone from outside the model domain (O_3-INFLOW) and the other half was formed by ozone precursors (O_3-PBL) emitted in eastern, central, and southern China. In the O_3-PBL, 3.0% of the ozone was from Mt. Huang reflecting the small local contribution (O_3-LOC) and the non-local contributions (O_3-NLOC) accounted for 41.6%, in which ozone from the southerly regions contributed significantly, for example, 9.9% of the ozone originating from Jiangxi, representing the highest geographical contributor. Because the origin and variation of O_3-NLOC was highly related to the diurnal movements in boundary layer, the similar diurnal patterns between O_3-NLOC and total ozone both indicated the direct influence of O_3-NLOC and the importance of boundary layer diurnal variations in the formation of such distinct diurnal ozone variations at Mt. Huang.

Purification and electronic characterisation of 18 isomers of the OPV acceptor material bis-[60]PCBM

The as-produced isomer mixture of the organic photovoltaic device acceptor material bis-[60]PCBM has been purified into its constituents by peak-recycling HPLC, and those individual isomers were characterised by UV-Vis absorption spectroscopy and cyclic voltammetry.

Imaging study of using radiopharmaceuticals labeled with cyclotron-produced 99mTc

Cyclotron-produced ^99mTc (CPTc) has been recognized as an attractive and practical substitution of reactor/generator based ^99mTc. However, the small amount of ^92-98Mo in the irradiation of enriched ¹⁰⁰Mo could lead to the production of other radioactive technetium isotopes (Tc-impurities) which cannot be chemically separated. Thus, these impurities could contribute to patient dose and affect image quality. The potential radiation dose caused by these Tc-impurities produced using different targets, irradiation conditions, and corresponding to different injection times have been investigated, leading us to create dose-based limits of these parameters for producing clinically acceptable CPTc. However, image quality has been not considered. The aim of the present work is to provide a comprehensive and quantitative analysis of image quality for CPTc. The impact of Tc-impurities in CPTc on image resolution, background noise, and contrast is investigated by performing both Monte-Carlo simulations and phantom experiments. Various targets, irradiation, and acquisition conditions are employed for investigating the image-based limits of CPTc production parameters. Additionally, the relationship between patient dose and image quality of CPTc samples is studied. Only those samples which meet both dose- and image-based limits should be accepted in future clinical studies.

Stroke increases the risk of hip fracture: a systematic review and meta-analysis

Many studies have investigated the association between stroke and hip fracture risk, but the precise association was still unclear due to insufficient statistical power in single studies with relatively small sample size. Thus, we firstly conducted a meta-analysis of all published studies to precisely estimate the relationship of stroke with hip fracture risk. The strength for this relationship was weighed by pooled relative risks (RRs) with 95 % confidence intervals (95 % CIs) after adjustment for confounding variables. Stratified analyses by study design and ethnicity and sensitivity analysis were also performed. Two investigators independently performed a comprehensive literature search in databases of PubMed, Embase, and Wanfang for eligible articles. A Bayesian meta-analysis was also performed to get a more precise assessment of the relationship. Eleven relevant studies from 10 publications were finally included into our meta-analysis according to the inclusion criteria. Overall, stroke significantly and independently increased the risk of hip fracture (RR = 2.06, 95 % CI 1.68-2.52, P < 0.001). Bayesian meta-analysis showed that stroke was also associated with an over two-fold increased risk of hip fracture (RR = 2.11, 95 % CI 1.62-2.75). In stratified analysis, stroke could increase the risk of hip fracture in Caucasians (RR = 2.36, 95 % CI 1.83-3.05, P < 0.001). These data support the notion that stroke is an independent risk factor for hip fracture, and patients with stroke have a two-fold increased risk of hip fracture than those without stroke.

Effect of Selenium Supplementation on Recurrent Hyperthyroidism Caused by Graves' Disease: A Prospective Pilot Study

The effect of selenium supplementation on recurrent hyperthyroidism caused by Graves' disease is unclear. Our study aimed to assess the efficacy of selenium supplementation therapy on recurrent Graves' disease. Forty-one patients with recurrent Graves' disease were enrolled in this study. All patients received the routine treatment using methimazole (MMI), while patients allocated to the selenium group received additional selenium therapy for 6 months. The influence of selenium supplementation on the concentrations of thyroid stimulating hormone (TSH), anti-TSH-receptor antibodies (TRAb), free thyroxine (FT4), and free triiodothyronine (FT3) were assessed. The remission rate was also compared between 2 groups. There was no obvious difference in the demographic data and the levels of serum FT4, FT3, TSH, and TRAb between the 2 groups at baseline. Both FT4 and FT3 decreased more at 2 months in the selenium group than the controls, while the TSH level increased more in patients receiving selenium supplementation (p<0.05). The TRAb level was significantly lower in patients receiving selenium supplementation (2.4 IU/l vs. 5.6 IU/l, p=0.04). The percentages of patients with normal TRAb level at 6 months was also significantly higher in the selenium group (19.0 vs. 0%, p=0.016). Kaplan-Meier survival curve showed patients receiving selenium supplementation had a significantly higher rate of remission than controls (Log-rank test p=0.008). In conclusion, selenium supplementation can enhance the effect of antithyroid drugs in patients with recurrent Graves' disease. Randomized trials with large number of participants are needed to validate the finding above.

Measurement of the high-energy gamma-ray emission from the Moon with the Fermi Large Area Telescope

We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

Clinical profile of diabetic ketoacidosis in tertiary hospitals in China: a multicentre, clinic-based study

AIMS

To evaluate the clinical profile of patients with diabetic ketoacidosis in tertiary hospitals in China.

METHODS

A retrospective study of patients hospitalized with diabetic ketoacidosis between 2010 and 2012 was carried out in 15 tertiary hospitals around China. Clinical and laboratory data were collected. Patients were classified based on clinical diagnosis and treatment history. Groups were compared for differences in vital statistics and biochemical profiles at presentation.

RESULTS

The study comprised 643 patients with diabetic ketoacidosis: 308 patients (47.9%) with Type 1 diabetes, 294 patients (45.7%) with Type 2 diabetes and 41 patients (6.4%) with atypical diabetes. Three hundred and eighty-eight diabetic ketoacidosis episodes (60.3%) were in patients with known diabetes. The most common precipitating factor was infection (40.1%), followed by unknown causes (36.9%) and non-compliance with anti-diabetes treatment (16.8%). At presentation, gastrointestinal symptoms and dehydration were more common in the Type 1 diabetes group. For new-onset diabetes, only 74.4% and 55.9% of patients were evaluated for β-cell function and autoantibodies for classification. Only 67% of patients with diabetic ketoacidosis received appropriate fluid therapy and 56% patients with severe acidosis received bicarbonate therapy. The length of hospital stay was 10.0 (7.0-14.0) days. The mortality rate was 1.7%, and was much higher in Type 2 diabetes than that in Type 1 diabetes (3.2% vs. 0.4%, P < 0.01).

CONCLUSIONS

Type 2 and Type 1 diabetes contribute to a similar proportion of cases presenting with diabetic ketoacidosis in China. Admissions with diabetic ketoacidosis are still associated with significant mortality and prolonged hospitalization. The efficiency of diabetic ketoacidosis management needs to be improved by implementing the updated guidelines.

QSAR study on the antimalarial activity of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) inhibitors

Plasmodium falciparum, the most fatal parasite that causes malaria, is responsible for over one million deaths per year. P. falciparum dihydroorotate dehydrogenase (PfDHODH) has been validated as a promising drug development target for antimalarial therapy since it catalyzes the rate-limiting step for DNA and RNA biosynthesis. In this study, we investigated the quantitative structure-activity relationships (QSAR) of the antimalarial activity of PfDHODH inhibitors by generating four computational models using a multilinear regression (MLR) and a support vector machine (SVM) based on a dataset of 255 PfDHODH inhibitors. All the models display good prediction quality with a leave-one-out q(2) >0.66, a correlation coefficient (r) >0.85 on both training sets and test sets, and a mean square error (MSE) <0.32 on training sets and <0.37 on test sets, respectively. The study indicated that the hydrogen bonding ability, atom polarizabilities and ring complexity are predominant factors for inhibitors' antimalarial activity. The models are capable of predicting inhibitors' antimalarial activity and the molecular descriptors for building the models could be helpful in the development of new antimalarial drugs.