Helicobacter pylori (H. pylori) is a common human pathogen responsible for various gastric diseases. This bacterium relies on the production of urease and hydrogenase to inhabit the acidic environment of the stomach. Nickel is an essential cofactor for urease and hydrogenase. H. pylori has to uptake sufficient nickel ions for the maturation of urease, and on the other way, to prevent the toxic effects of excessive nickel ions. Therefore, H. pylori has to strike a delicate balance between the import of nickel ions, its efficient intracellular storage, and delivery to nickel-dependent metalloenzymes when required. The assembly and maturation of the urease enzyme is a complex and timely ordered process, requiring various regulatory, uptake, chaperone and accessory proteins. In this review, we focus on several nickel trafficking proteins involved in urease maturation: NikR, NixA, HypAB, UreEFGH, HspA, Hpn and Hpnl. The work will deepen our understanding of how this pathogenic bacterium adapts to severe habitant environments in the host.
Urease; Histidine-rich protein; NikR; NixA; Helicobacter pylori
The pluripotency factor Lin28 blocks the expression of let-7 microRNAs (miRNAs) in undifferentiated cells during development and functions as an oncogene in a subset of cancers1. Lin28 binds to let-7 precursor RNAs and recruits 3′ terminal uridylyl transferases (TUTases) to selectively inhibit let-7 biogenesis2–4. Uridylated pre-let-7 is refractory to processing by Dicer and is rapidly degraded by an unknown ribonuclease5. Here we identify Dis3l2 as the 3′-5′ exonuclease responsible for the decay of uridylated pre-let-7. Biochemical reconstitution assays reveal that 3′ oligouridylation stimulates Dis3l2 activity in vitro, and knockdown of Dis3l2 in mouse embryonic stem cells leads to the stabilization of pre-let-7. Our study establishes 3′ oligouridylation as an RNA decay signal for Dis3l2 and identifies the first physiological RNA substrate of this novel exonuclease that is mutated in the Perlman syndrome of fetal overgrowth and predisposition to Wilms’ tumor6.
Dis3l2; exonuclease; uridylation; Lin-28; Lin28; let-7; microRNA (miRNA); TUTase; Embryonic Stem Cells
Background and aim
Limitations of the currently recommended stepwise treatment pathway for type 2 diabetes mellitus (T2DM), especially the failure of monotherapies to maintain good glycemic control, have prompted use of early, more aggressive combination therapies.
The VISION study is designed to explore the efficacy and safety of vildagliptin as an add-on to metformin therapy compared with up-titration of metformin monotherapy in Chinese patients with T2DM.
VISION, a 24-week, phase 4, prospective, randomized, multicenter, open-label, parallel-group study, will include 3312 Chinese T2DM patients aged ≥18 years who are inadequately controlled (6.5% >HbA1c ≤9%) by metformin (750–1000 mg/day). Eligible patients will be randomized to receive either vildagliptin plus metformin or up-titration of metformin monotherapy (5:1). Patients will also be subgrouped (1:1:1:1) based on their age and body mass index (BMI): <60 years and <24 kg/m2; <60 years and ≥24 kg/m2; ≥60 years and <24 kg/m2; and ≥60 years and ≥24 kg/m2.
The VISION study will test the hypothesis that early use of combination therapy with vildagliptin and metformin will provide good glycemic control and will be better tolerated than up-titration of metformin monotherapy. The study will also correlate these benefits with age and BMI.
VISION study; Vildagliptin; Type 2 diabetes; Study design; DPP-IV inhibitors
The prevalence of type 2 diabetes mellitus (T2DM) is increasing rapidly among Chinese adults, and limited data are available on T2DM management and the status of glycemic control in China. We assessed the efficacy of oral antidiabetes drugs (OADs), glucagon-like peptide-1 (GLP-1) receptor agonists, and insulin for treatment of T2DM across multiple regions in China.
This was a multicenter, cross-sectional survey of outpatients conducted in 606 hospitals across China. Data from all the patients were collected between April and June, 2011.
A total of 238,639 patients were included in the survey. Eligible patients were treated with either OADs alone (n=157,212 [65.88%]), OADs plus insulin (n=80,973 [33.93%]), or OADs plus GLP-1 receptor agonists (n=454 [0.19%]). The OAD monotherapy, OAD + insulin, and OAD + GLP-1 receptor agonist groups had mean glycosylated hemoglobin (HbA1c) levels (±SD) of 7.67% (±1.58%), 8.21% (±1.91%), and 7.80% (±1.76%), respectively. Among those three groups, 34.63%, 26.21%, and 36.12% met the goal of HbA1c <7.0%, respectively. Mean HbA1c and achievement of A1c <7.0% was related to the duration of T2DM.
Less than one third of the patients had achieved the goal of HbA1c <7.0%. Glycemic control decreased and insulin use increased with the duration of diabetes.
China; GLP-1 receptor agonists; HbA1c; Insulin; Oral antidiabetes drugs (OADs); Type 2 diabetes mellitus
Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation.
Although research has provided abundant evidence for Taichi-induced improvements in psychological and physiological well-being, little is known about possible links to brain structure of Taichi practice. Using high-resolution MRI of 22 Tai Chi Chuan (TCC) practitioners and 18 controls matched for age, sex and education, we set out to examine the underlying anatomical correlates of long-term Taichi practice at two different levels of regional specificity. For this purpose, parcel-wise and vertex-wise analyses were employed to quantify the difference between TCC practitioners and the controls based on cortical surface reconstruction. We also adopted the Attention Network Test (ANT) to explore the effect of TCC on executive control. TCC practitioners, compared with controls, showed significantly thicker cortex in precentral gyrus, insula sulcus and middle frontal sulcus in the right hemisphere and superior temporal gyrus and medial occipito-temporal sulcus and lingual sulcus in the left hemisphere. Moreover, we found that thicker cortex in left medial occipito-temporal sulcus and lingual sulcus was associated with greater intensity of TCC practice. These findings indicate that long-term TCC practice could induce regional structural change and also suggest TCC might share similar patterns of neural correlates with meditation and aerobic exercise.
To study the D-genome of the wild wheat relative Aegilops tauschii Cosson at the hexaploid level, we developed a synthetic doubled-haploid (DH) hexaploid wheat population, SynDH3. This population was derived from the spontaneous chromosome doubling of triploid F1 hybrid plants obtained from a cross between Triticum turgidum ssp. dicoccon PI377655 and A. tauschii ssp. strangulata AS66 × ssp. tauschii AS87. SynDH3 is a diploidization-hexaploid DH population containing recombinant D chromosomes from two different A. tauschii genotypes, with A and B chromosomes from T. turgidum being homogenous across the entire population. Using this population, we constructed a genetic map. Of the 440 markers used to construct the map, 421 (96%) were assigned to 12 linkage groups; these included 346 Diversity Arrays Technology (DArT) and 75 simple sequence repeat (SSR) markers. The total map length of the seven D chromosomes spanned 916.27 cM, with an average length of 130.90 cM per chromosome and an average distance between markers of 3.47 cM. Seven segregation distortion regions were detected on seven linkage groups. Out of 50 markers shared with those on a common wheat map, 37 showed a consistent order. The utility of the diploidization-hexaploid DH population for mapping qualitative trait genes was confirmed using the dominant glaucousness-inhibiting gene W2I as an example.
Electronic supplementary material
The online version of this article (doi:10.1186/2193-1801-2-131) contains supplementary material, which is available to authorized users.
Allopolyploid; Aegilops tauschii; Doubled-haploid; Segregation distortion
An actual account of the angle random walk (ARW) coefficients of gyros in the constant rate biased rate ring laser gyro (RLG) inertial navigation system (INS) is very important in practical engineering applications. However, no reported experimental work has dealt with the issue of characterizing the ARW of the constant rate biased RLG in the INS. To avoid the need for high cost precise calibration tables and complex measuring set-ups, the objective of this study is to present a cost-effective experimental approach to characterize the ARW of the gyros in the constant rate biased RLG INS. In the system, turntable dynamics and other external noises would inevitably contaminate the measured RLG data, leading to the question of isolation of such disturbances. A practical observation model of the gyros in the constant rate biased RLG INS was discussed, and an experimental method based on the fast orthogonal search (FOS) for the practical observation model to separate ARW error from the RLG measured data was proposed. Validity of the FOS-based method was checked by estimating the ARW coefficients of the mechanically dithered RLG under stationary and turntable rotation conditions. By utilizing the FOS-based method, the average ARW coefficient of the constant rate biased RLG in the postulate system is estimated. The experimental results show that the FOS-based method can achieve high denoising ability. This method estimate the ARW coefficients of the constant rate biased RLG in the postulate system accurately. The FOS-based method does not need precise calibration table with high cost and complex measuring set-up, and Statistical results of the tests will provide us references in engineering application of the constant rate biased RLG INS.
rate biased technique; ring laser gyro; fast orthogonal search; Allan variance
A wide range of microalbuminuria cutoff values are currently used for diagnosing the early stage of nephropathy in type 2 diabetes (T2D). This study analyzed the relationships between oxidant and antioxidant markers of nephropathy and the severity of microalbuminuria. The study included 50 healthy controls (Group 1), 50 diabetic patients with no nephropathy (Group 2), 50 diabetic patients with nephropathy and a urinary albumin excretion (UAE) of 30–200 mg/24 h (Group 3), and 50 diabetic patients with UAE 200–300 mg/24 h (Group 4). Serum nitrotyrosine, conjugated dienes, 8-hydroxy-2′-deoxyguanosine (8-OHdG), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) levels were determined. Oxidative stress is increased in the early stage of nephropathy in patients with T2D. There was a significant correlation between the extent of microalbuminuria and markers of oxidative stress. Multiple linear regression analysis identified lipid oxidative stress as a possible independent marker for evaluating the degree of renal damage in diabetic nephropathy. Stratifying microalbuminuria values during the early stage of nephropathy might be an important factor in facilitating earlier and more specific interventions.
Pluripotent embryonic stem cells (ESCs) have a shortened cell cycle that enables their rapid proliferation. The ESC-specific miR-290 and miR-302 microRNA families promote proliferation whereas let-7 microRNAs inhibit self-renewal and promote cell differentiation. Lin28 suppresses let-7 expression in ESCs. Here, to gain further insight into mechanisms controlling ESC self-renewal we explore the molecular and cellular role of the let-7 target Trim71 (mLin41). We show that Trim71 associates with Argonaute2 (Ago2) and microRNAs and represses expression of Cdkn1a, a cyclin-dependent kinase inhibitor that negatively regulates the G1–S transition. We identify protein domains required for Trim71 association with Ago2, localization to P-bodies, and for repression of reporter mRNAs. Trim71 knockdown prolongs the G1 phase of the cell cycle and slows ESC proliferation, a phenotype that was rescued by depletion of Cdkn1a. Thus, we demonstrate Trim71 is a factor that facilitates the G1–S transition to promote rapid ESC self-renewal.
A synthetic doubled-haploid hexaploid wheat population, SynDH1, derived from the spontaneous chromosome doubling of triploid F1 hybrid plants obtained from the cross of hybrids Triticum turgidum ssp. durum line Langdon (LDN) and ssp. turgidum line AS313, with Aegilops tauschii ssp. tauschii accession AS60, was previously constructed. SynDH1 is a tetraploidization-hexaploid doubled haploid (DH) population because it contains recombinant A and B chromosomes from two different T. turgidum genotypes, while all the D chromosomes from Ae. tauschii are homogenous across the whole population. This paper reports the construction of a genetic map using this population.
Of the 606 markers used to assemble the genetic map, 588 (97%) were assigned to linkage groups. These included 513 Diversity Arrays Technology (DArT) markers, 72 simple sequence repeat (SSR), one insertion site-based polymorphism (ISBP), and two high-molecular-weight glutenin subunit (HMW-GS) markers. These markers were assigned to the 14 chromosomes, covering 2048.79 cM, with a mean distance of 3.48 cM between adjacent markers. This map showed good coverage of the A and B genome chromosomes, apart from 3A, 5A, 6A, and 4B. Compared with previously reported maps, most shared markers showed highly consistent orders. This map was successfully used to identify five quantitative trait loci (QTL), including two for spikelet number on chromosomes 7A and 5B, two for spike length on 7A and 3B, and one for 1000-grain weight on 4B. However, differences in crossability QTL between the two T. turgidum parents may explain the segregation distortion regions on chromosomes 1A, 3B, and 6B.
A genetic map of T. turgidum including 588 markers was constructed using a synthetic doubled haploid (SynDH) hexaploid wheat population. Five QTLs for three agronomic traits were identified from this population. However, more markers are needed to increase the density and resolution of this map in the future study.
Allopolyploid; Crossability; Doubled haploid; Segregation distortion
Simple sequence repeats (SSRs, also known as microsatellites) are known to be mutational hotspots in genomes. DNA rearrangements have also been reported to accompany allopolyploidization. A study of the effect of allopolyploidization on SSR mutation is therefore important for understanding the origin and evolutionary dynamics of SSRs in allopolyploids. Three synthesized double haploid (SynDH) populations were made from 241 interspecific F1 haploid hybrids between Triticum turgidum L. and Aegilops tauschii (Coss.) through spontaneous chromosome doubling via unreduced gametes. Mutation events were studied at 160 SSR loci in the S1 generation (the first generation after chromosome doubling) of the three SynDH populations. Of the 148260 SSR alleles investigated in S1 generation, only one mutation (changed number of repeats) was confirmed with a mutation rate of 6.74 × 10−6. This mutation most likely occurred in the respective F1 hybrid. In comparison with previously reported data, our results suggested that allohexaploidization of wheat did not increase SSR mutation rate.
allopolyploidy; distant hybridization; microsatellite evolution; wheat
Overweight and obesity are considered a serious health problem. There are little data on the prevalence of overweight and obesity among the Yi ethnic group in China. This study aimed to investigate the epidemiologic features of overweight/obesity among Chinese Yi nationality.
A cross-sectional study, including 1255 subjects aged 20-75 years, was carried out in Liangshan Yi Autonomous Prefecture of Sichuan province from 2007 to 2008. Overweight/overall obesity was defined by World Health Organization (WHO) or the Working Group on Obesity in China.
Overall, the prevalence of overweight and obesity was 19.0% and 2.9%, respectively, based on the WHO definition, while it was 21.0% and 7.4%, respectively, according to the Working Group on Obesity in China, which is similar to data reported in the 2002 Chinese National Nutrition and Health Survey. Urban residents had a significantly higher prevalence of obesity (WHO criteria: 4.3% vs 1.7% p = 0.008; China criteria: 11.4% vs 3.7%, p < 0.001) and overweight (WHO criteria: 28.9% vs 8.9% p < 0.001; China criteria: 31.2% vs 10.4%, p < 0.001) than that in rural residents. Older age, a family history of obesity, higher income, drinking and urban residence were significantly associated with an increased risk of overweight/obesity.
The prevalence of overweight/obesity in the Yi nationality is similar to that in Chinese adults 5 years ago. However, urban residents have a much higher prevalence of overweight/obesity than their rural counterparts. Lifestyle and diet patterns associated with socioeconomic status may explain the difference between urban and rural residents. The prevention of overweight/obesity among urban inhabitants deserves more attention in national health education programs.
Imaging of non-linear optical (NLO) signals generated from the eye using ultrafast pulsed lasers has been limited to the study of ex vivo tissues because of the use of conventional microscopes with slow scan speeds. The purpose of this study was to evaluate the ability of a novel, high scan rate ophthalmoscope to generate NLO signals using an attached femtosecond laser. NLO signals were generated and imaged in live, anesthetized albino rabbits using a newly designed Heidelberg Two-Photon Laser Ophthalmoscope with attached 25 mW femtosecond laser having a central wavelength of 780 nm, pulsewidth of 75 fs, and a repetition rate of 50 MHz. To assess two-photon excited fluorescent (TPEF) signal generation, cultured rabbit corneal fibroblasts (RCF) were first labeled by Blue-green fluorescent FluoSpheres (1 μm diameter) and then cells were micro-injected into the central cornea. Clumps of RCF cells could be detected by both reflectance and TPEF imaging at 6 hours after injection. By 6 days, RCF containing fluorescent microspheres confirmed by TPEF showed a more spread morphology and had migrated from the original injection site. Overall, this study demonstrates the potential of using NLO microscopy to sequentially detect TPEF signals from live, intact corneas. We conclude that further refinement of the Two-photon laser Ophthalmoscope should lead to the development of an important, new clinical instrument capable of detecting NLO signals from patient corneas.
Two-Photon Excited Fluorescence; Microspheres; Rabbit Cornea; Fibroblast; In Vivo Confocal
AIM: To investigate how to reduce the incidence of biliary complications in rat orthotopic liver transplantation.
METHODS: A total of 165 male Wistar rats were randomly divided into three groups: Group A, orthotropic liver transplantation with modified “two-cuff” technique; Group B, bile duct was cut and reconstructed without transplantation; and Group C, only laparotomy was performed. Based on the approaches used for biliary reconstruction, Group A was divided into two sub-groups:A1 (n = 30), duct-duct reconstruction, and A2 (n = 30), duct-duodenum reconstruction. To study the influence of artery reconstruction on bile duct complication, Group B was divided into four sub-groups: B1 (n = 10), duct-duct reconstruction with hepatic artery ligation, B2 (n = 10), duct-duct reconstruction without hepatic artery ligation, B3 (n = 10), duct-duodenum reconstruction with hepatic artery ligation, and B4 (n = 10), duct-duodenum reconstruction without hepatic artery ligation. The samples were harvested 14 d after operation or at the time when significant biliary complication was found.
RESULTS: In Group A, the anhepatic phase was 13.7 ± 1.06 min, and cold ischemia time was 50.5 ± 8.6 min. There was no significant difference between A1 and A2 in the operation duration. The time for biliary reconstruction was almost the same among all groups. The success rate for transplantation was 98.3% (59/60). Significant differences were found in the incidence of biliary complications in Groups A (41.7%), B (27.5%) and C (0%). A2 was more likely to have biliary complications than A1 (50% vs 33.3%). B3 had the highest incidence of biliary complications in Group B.
CONCLUSION: Biliary complications are almost inevitable using the classical “two cuff” techniques, and duct-duodenum reconstruction is not an ideal option in rat orthotopic liver transplantation.
Rat; Liver transplantation; Biliary complication; Animal model
A villous adenoma is an extremely rare benign tumour in the appendix, in contrast to other benign appendiceal lesions. The clinical features are usually asymptomatic. Acute appendicitis is the most common complication with the lesion obstructing the orifice of the appendiceal lumen. Thus, a villous adenoma is usually found during surgical intervention for acute appendicitis. Mechanical obstruction induced by acute perforated appendicitis has been previously reported. Acute appendicitis caused by a villous adenoma presenting with acute intestinal obstruction has not been previously reported.
A 78-year-old woman presented to our Emergency Department with diffuse abdominal pain and tenderness. The abdominal plain film and computed tomography revealed an intestinal obstruction. After surgical intervention, the ruptured appendix was shown to be associated with intestinal obstruction. The post-operative pathologic diagnosis was an appendiceal villous adenoma.
This is the first report describing an appendiceal villous adenoma, which is an occasional cause of perforated acute appendicitis, presenting as a complete intestinal obstruction. We emphasize that in elderly patients without a surgical history, the occult cause of complete intestinal obstruction must be determined. If an appendiceal tumour is diagnosed, an intra-operative frozen section is suggested prior to selecting a suitable method of surgical intervention.
Experimental pEC50s for 216 selective respiratory syncytial virus (RSV) inhibitors are used to develop classification models as a potential screening tool for a large library of target compounds. Variable selection algorithm coupled with random forests (VS-RF) is used to extract the physicochemical features most relevant to the RSV inhibition. Based on the selected small set of descriptors, four other widely used approaches, i.e., support vector machine (SVM), Gaussian process (GP), linear discriminant analysis (LDA) and k nearest neighbors (kNN) routines are also employed and compared with the VS-RF method in terms of several of rigorous evaluation criteria. The obtained results indicate that the VS-RF model is a powerful tool for classification of RSV inhibitors, producing the highest overall accuracy of 94.34% for the external prediction set, which significantly outperforms the other four methods with the average accuracy of 80.66%. The proposed model with excellent prediction capacity from internal to external quality should be important for screening and optimization of potential RSV inhibitors prior to chemical synthesis in drug development.
RSV; variable selection; Mold2 descriptors; random forest
5-HT6 receptor has been implicated in a series of diseases including anxiety, depression, schizophrenia and cognitive dysfunctions. 5-HT6 ligands have been reported to play a significant role in the treatment for central nervous system (CNS) diseases. Presently, a large series of 223 5-HT6 ligands were studied using a combinational method by 3D-QSAR, molecular docking and molecular dynamics calculations for further improvement of potency. The optimal 3D models exhibit satisfying statistical results with r2ncv, q2 values of 0.85 and 0.50 for CoMFA, 0.81 and 0.53 for CoMSIA, respectively. Their predictive powers were validated by external test set, showing r2pred of 0.71 and 0.76. The contour maps also provide a visual representation of contributions of steric, electrostatic, hydrophobic and hydrogen bond fields as well as the prospective binding models. In addition, the agreement between 3D-QSAR, molecular docking and molecular dynamics simulation proves the rationality of the developed models. These results, we hope, may be helpful in designing novel and potential 5-HT6 ligands.
5-HT6; 3D-QSAR; CoMFA; CoMSIA; molecular dynamics
MGluR2 is G protein-coupled receptor that is targeted for diseases like anxiety, depression, Parkinson’s disease and schizophrenia. Herein, we report the three-dimensional quantitative structure–activity relationship (3D-QSAR) studies of a series of 1,3-dihydrobenzo[ b][1,4]diazepin-2-one derivatives as mGluR2 antagonists. Two series of models using two different activities of the antagonists against rat mGluR2, which has been shown to be very similar to the human mGluR2, (activity I: inhibition of [3H]-LY354740; activity II: mGluR2 (1S,3R)-ACPD inhibition of forskolin stimulated cAMP.) were derived from datasets composed of 137 and 69 molecules respectively. For activity I study, the best predictive model obtained from CoMFA analysis yielded a Q2 of 0.513, R2 ncv of 0.868, R2 pred = 0.876, while the CoMSIA model yielded a Q2 of 0.450, R2 ncv = 0.899, R2 pred = 0.735. For activity II study, CoMFA model yielded statistics of Q2 = 0.5, R2 ncv = 0.715, R2 pred = 0.723. These results prove the high predictability of the models. Furthermore, a combined analysis between the CoMFA, CoMSIA contour maps shows that: (1) Bulky substituents in R7, R3 and position A benefit activity I of the antagonists, but decrease it when projected in R8 and position B; (2) Hydrophilic groups at position A and B increase both antagonistic activity I and II; (3) Electrostatic field plays an essential rule in the variance of activity II. In search for more potent mGluR2 antagonists, two pharmacophore models were developed separately for the two activities. The first model reveals six pharmacophoric features, namely an aromatic center, two hydrophobic centers, an H-donor atom, an H-acceptor atom and an H-donor site. The second model shares all features of the first one and has an additional acceptor site, a positive N and an aromatic center. These models can be used as guidance for the development of new mGluR2 antagonists of high activity and selectivity. This work is the first report on 3D-QSAR modeling of these mGluR2 antagonists. All the conclusions may lead to a better understanding of the mechanism of antagonism and be helpful in the design of new potent mGluR2 antagonists.
3D-QSAR; mGluR2 antagonist; CoMFA; CoMSIA; pharmacophore modeling
Fructose 1,6-bisphosphatase (FBPase) has been identified as a drug discovery target for lowering glucose in type 2 diabetes mellitus. In this study, a large series of 105 FBPase inhibitors were studied using a combinational method by 3D-QSAR, molecular docking and molecular dynamics simulations for a further improvement in potency. The optimal 3D models exhibit high statistical significance of the results, especially for the CoMFA results with rncv2, q2 values of 0.986, 0.514 for internal validation, and rpred2, rm2 statistics of 0.902, 0.828 statistics for external validation. Graphic representation of the results, as contoured 3D coefficient plots, also provides a clue to the reasonable modification of molecules. (1) Substituents with a proper length and size at the C5 position of the thiazole core are required to enhance the potency; (2) A small and electron-withdrawing group at the C2 position linked to the thiazole core is likely to help increase the FBPase inhibition; (3) Substituent groups as hydrogen bond acceptors at the C2 position of the furan ring are favored. In addition, the agreement between 3D-QSAR, molecular docking and molecular dynamics simulation proves the rationality of the developed models. These results, we hope, may be helpful in designing novel and potential FBPase inhibitors.
3D-QSAR; molecular dynamics; FBPase inhibitors; CoMFA; CoMSIA
This work is devoted to the prediction of a series of 208 structurally diverse PKCθ inhibitors using the Random Forest (RF) based on the Mold2 molecular descriptors. The RF model was established and identified as a robust predictor of the experimental pIC50 values, producing good external R2pred of 0.72, a standard error of prediction (SEP) of 0.45, for an external prediction set of 51 inhibitors which were not used in the development of QSAR models. By using the RF built-in measure of the relative importance of the descriptors, an important predictor—the number of group donor atoms for H-bonds (with N and O)—has been identified to play a crucial role in PKCθ inhibitory activity. We hope that the developed RF model will be helpful in the screening and prediction of novel unknown PKCθ inhibitory activity.
protein kinase C θ; Random Forest; Partial Least Square; Support Vector Machine
Attention deficit/hyperactivity disorder (ADHD) and lead exposure are high-prevalence conditions among children.
Our goal was to investigate the association between ADHD and blood lead levels (BLLs) in Chinese children, adjusting for known ADHD risk factors and potential confounding variables.
We conducted a pair-matching case–control study with 630 ADHD cases and 630 non-ADHD controls 4–12 years of age, matched on the same age, sex, and socioeconomic status. The case and control children were systematically evaluated via structured diagnostic interviews, including caregiver interviews, based on the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., revised criteria (DSM-IV-R). We evaluated the association between BLLs and ADHD using the Pearson chi-square test for categorical variables and the Student t-test for continuous data. We then performed conditional multiple variables logistic regression analyses with backward stepwise selection to predict risk factors for ADHD.
There was a significant difference in BLLs between ADHD cases and controls. ADHD cases were more likely to have been exposed to lead during childhood than the non-ADHD control subjects, with adjustment for other known risk factors [children with BLLs ≥ 10 μg/dL vs. ≤ 5 μg/dL; OR = 6.0; 95% confidence interval (CI) = 4.10–8.77, p < 0.01; 5–10 μg/dL vs.≤ 5 μg/dL, OR = 4.9; 95% CI = 3.47–6.98, p < 0.01]. These results were not modified by age and sex variables.
This was the largest sample size case–control study to date to study the association between BLLs and ADHD in Chinese children. ADHD may be an additional deleterious outcome of lead exposure during childhood, even when BLLs are < 10 μg/dL.
attention deficit hyperactivity disorder; blood lead levels; case-control study
In the title compound, [Zn(H2O)6](C13H10NO4S)2, a distorted ZnO6 octahedron results from the coordination by the six water molecules. Only three of the water molecules are crystallographically unique, as the Zn atom lies on an inversion center. The Zn—O bond lengths are in the range 2.054 (4)–2.073 (4) Å. A network of hydrogen bonds helps to establish the crystal packing.
Tocopherols are important antioxidants in lipophilic environments. They are synthesized by plants and some photosynthetic bacteria. Recent efforts to analyze and engineer tocopherol biosynthesis led to the identification of Synechocystis sp. strain PCC 6803 as a well-characterized model system. To facilitate the identification of the rate-limiting step(s) in the tocopherol biosynthetic pathway through the modulation of transgene expression, we established an inducible expression system in Synechocystis sp. strain PCC 6803. The nirA promoter from Synechococcus sp. strain PCC 7942, which is repressed by ammonium and induced by nitrite (S.-I. Maeda et al., J. Bacteriol. 180:4080-4088, 1998), was chosen to drive the expression of Arabidopsis thaliana p-hydroxyphenylpyruvate dioxygenase. The enzyme catalyzes the formation of homogentisic acid from p-hydroxyphenylpyruvate. Expression of this gene under inducing conditions resulted in up to a fivefold increase in total tocopherol levels with up to 20% of tocopherols being accumulated as tocotrienols. The culture supernatant of these cultures exhibited a brown coloration, a finding indicative of homogentisic acid excretion. Enzyme assays, functional complementation, reverse transcription-PCR, and Western blot analysis confirmed transgene expression under inducing conditions only. These data demonstrate that the nirA promoter can be used to control transgene expression in Synechocystis and that homogentisic acid is a limiting factor for tocopherol synthesis in Synechocystis sp. strain PCC 6803.