Effect of introducing disulfide bridges in C-terminal structure on the thermostability of xylanase XynZF-2 from Aspergillus niger

In this study, a mutant xylanase of high thermostability was obtained by site-directed mutagenesis. The homologous 3D structure of xylanase was successfully modeled and the mutation sites were predicted using bioinformatics software. Two amino acids of XynZF-2 were respectively substituted by cysteines (T205C and A52C) and a disulfide bridge was introduced into the C-terminal of XynZF-2. The mutant gene xynZFTA was cloned into pPIC9K and expressed in P. pastoris. The optimum temperature of the variant XynZFTA was improved from 45°C to 60°C, and XynZFTA retained greater than 90.0% activity (XynZF-2 retained only 50.0% activity) after treatment at 50°C for 5 min. The optimum pH of mutant xylanase was similar to XynZF-2 (pH = 5.0). The pH stability span (5.0~7.0) of the mutant xylanase was increased to 3.0~9.0. Overall, the results implied that the introduction of a disulfide bridge in the C-terminal structure improved the thermostability and pH stability of XynZF-2.

A long-acting pegylated recombinant human growth hormone (Jintrolong® ) in healthy adult subjects: Two single-dose trials evaluating safety, tolerability and pharmacokinetics

WHAT IS KNOWN AND OBJECTIVE

Jintrolong^® is a pegylated recombinant human growth hormone (rhGH) (PEG-rhGH) developed for weekly subcutaneous (sc) injection. The current human tolerability trial and pharmacokinetics (PK) trial evaluated the safety, tolerability and PK of single-dose Jintrolong^® injection in healthy adult subjects.

METHODS

Both trials were single-centre, randomized, open-label and single-dose studies. In the human tolerability trial, 34 healthy subjects were randomized to receive single-dose Jintrolong^® sc injection (0.01, 0.06, 0.2, 0.5 or 0.8 mg/kg) or placebo. In the PK study, 30 healthy male subjects were evenly randomized into 3 groups to receive single-dose Jintrolong^® sc injection (0.1, 0.2 or 0.4 mg/kg), and the subjects receiving 0.4 mg/kg Jintrolong^® were given a single sc injection of conventional rhGH (0.067 mg/kg) after a 14-day washout period. Safety and PK profiles of Jintrolong^® were evaluated.

RESULTS AND DISCUSSION

Jintrolong^® was well tolerated with no serious adverse events or local injection responses. The PK trial showed that the plasma growth hormone concentration elevated quickly and stayed at peak level between 12 and 48 hours post-Jintrolong^® injection, then decreased gradually back to baseline within 168 hours. Compared to single-dose conventional rhGH, Jintrolong^® at all doses demonstrated significantly longer half time and time to maximum plasma concentration, lower clearance and higher systemic drug exposure, indicating prolonged presence of GH in the subjects' circulation. Additionally, systemic exposure to Jintrolong^® increased in a dose-dependent manner.

WHAT IS NEW AND CONCLUSION

Single-dose Jintrolong^® injection was well tolerated in healthy adult subjects, and the maximum tolerable dose was no lower than 0.8 mg/kg. Jintrolong^® was long-acting with the potential for weekly administration.

Continuous Veno-Venous Hemofiltration in the Treatment of Acute Severe Hyponatremia: A Report of 11 Cases

Objectives

To evaluate the treatment effect of continuous veno-venous hemofiltration (CVVH) in patients with acute severe hyponatremia.

Methods

Eleven patients with severe acute hyponatremia, including 6 males and 5 females, aged 25–61 years (mean age 48.36), were treated with CVVH. Hyponatremia occurred 38–48 hours prior to the initiation of CVVH.

Results

All patients tolerated CVVH well, with an average treatment duration of 57.19 (45.6–86) hours. During CVVH, the serum sodium concentration increased significantly from 100.9±3.99 mmol/L at initiation of CVVH to 140.3±1.6 mmol/L after 48 hours of treatment (P<0.01). The serum osmolarity increased concurrently, from 216.7±7.4 mOsm/kgH2O to 295.0±4.2 mOsm/kgH2O (P<0.01). The Glasgow scores and APACHE II scores in these patients improved significantly during treatment.

Conclusions

CVVH is a safe and effective option for the treatment of patients with severe acute hyponatremia due to its slow and continuous nature.

Significant Decrease in Dialysate Albumin Concentration during Molecular Adsorbent Recirculating System (M.A.R.S.) Therapy

Aim

The molecular adsorbent recirculating system (M.A.R.S.) is widely used as liver support therapy in patients with hepatic dysfunction. The goal of this study was to measure changes in dialysate albumin and bilirubin concentrations during clinical MARS treatments.

Methods

Eight patients with acute liver dysfunction and hyperbilirubinemia were enrolled in this study. Five of them received a total of 10 treatments with MARS, in which 600 mL of 20% human albumin was used as dialysate, continuously regenerated by two adsorbent columns in the circuit. Three patients received 4 treatments of a modified MARS, in which the two adsorbent columns were bypassed in the first course for 4 h, and then connected to the circuit in the second course for another 4 h. The total, conjugated and unconjugated bilirubin (TB, CB, UCB) and albumin concentrations in serum and albumin dialysate were dynamically measured, and the adsorbent column inlet pressures were recorded during each session. In one session, dialysate albumin levels were measured during the priming process, at the time points prior to the priming process, immediately after priming, and at the end of the treatment.

Results

During MARS therapies, the reduction ratio of serum TB, CB and UCB was 26.6±9.0%, 29.5±9.6% and 14.8±12.3%, respectively. The molar ratio of TB/albumin in serum was approximately 20-fold higher than dialysate at all time points. A significant albumin concentration decrease from baseline in the dialysate was found (mean±SD, 34.6±16.6%). For the first four hours of modified treatments, in which only albumin dialysis without albumin regeneration by adsorbent columns was performed, the dialysate albumin decrease was substantially smaller (mean, 8.3±1.5%). After switching to standard MARS, there was a further decrease in the dialysate albumin concentration of 35.1±14.5%. In one session, dialysate albumin concentrations were measured during the priming process, and levels decreased from 196.9 g/L to 144.4 g/L. Adsorber inlet pressure increased from 40±10mmHg at the start of priming to 150±50mmHg at the end of priming, and further increased to 340±100mmHg at the end of treatment.

Conclusion

There is a significant reduction in dialysate albumin concentration during MARS therapy. Binding of albumin to the adsorbent columns used for albumin regeneration is largely responsible for this decrease.

Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay

This Letter reports a measurement of the flux and energy spectrum of electron antineutrinos from six 2.9 GWth nuclear reactors with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls in the Daya Bay experiment. Using 217 days of data, 296 721 and 41 589 inverse β decay (IBD) candidates were detected in the near and far halls, respectively. The measured IBD yield is (1.55±0.04) ×10(-18)  cm(2) GW(-1) day(-1) or (5.92±0.14) ×10(-43)  cm(2) fission(-1). This flux measurement is consistent with previous short-baseline reactor antineutrino experiments and is 0.946±0.022 (0.991±0.023) relative to the flux predicted with the Huber-Mueller (ILL-Vogel) fissile antineutrino model. The measured IBD positron energy spectrum deviates from both spectral predictions by more than 2σ over the full energy range with a local significance of up to ∼4σ between 4-6 MeV. A reactor antineutrino spectrum of IBD reactions is extracted from the measured positron energy spectrum for model-independent predictions.

d-Alanine metabolism is essential for growth and biofilm formation of Streptococcus mutans

Part of the d-alanine (d-Ala) metabolic pathway in bacteria involves the conversion of l-alanine to d-Ala by alanine racemase and the formation of d-alanyl-d-alanine by d-alanine-d-alanine ligase, the product of which is involved in cell wall peptidoglycan synthesis. At present, drugs that target the metabolic pathway of d-Ala are already in clinical use - e.g. d-cycloserine (DCS) is used as an antibiotic against Mycobacterium tuberculosis. Streptococcus mutans is the main cariogenic bacterium in the oral cavity. Its d-Ala metabolism-associated enzymes alanine racemase and d-alanine-d-alanine ligase are encoded by the genes smu.1834 and smu.599, respectively, which may be potential targets for inhibitors. In this study, the addition of DCS blocked the d-Ala metabolic pathway in S. mutans, leading to bacterial cell wall defects, significant inhibition of bacterial growth and biofilm formation, and reductions in extracellular polysaccharide production and bacterial adhesion. However, the exogenous addition of d-Ala could reverse the inhibitory effect of DCS. Through the means of drug regulation, our study demonstrated, for the first time, the importance of d-Ala metabolism in the survival and biofilm formation of S. mutans. If the growth of S. mutans can be specifically inhibited by designing drugs that target d-Ala metabolism, then this may serve as a potential new treatment for dental caries.

New measurement of antineutrino oscillation with the full detector configuration at Daya Bay

We report a new measurement of electron antineutrino disappearance using the fully constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×10^{5} GW_{th}  ton days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six ^{241}Am-^{13}C radioactive calibration sources reduced the background by a factor of 2 for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin^{2}2θ_{13} and |Δm_{ee}^{2}| were halved as a result of these improvements. An analysis of the relative antineutrino rates and energy spectra between detectors gave sin^{2}2θ_{13}=0.084±0.005 and |Δm_{ee}^{2}|=(2.42±0.11)×10^{-3}  eV^{2} in the three-neutrino framework.

Search for a light sterile neutrino at Daya Bay

A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) ≲ |Δm(41)(2)| ≲ 0.1 eV(2) region, which was largely unexplored.

Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

Pancreatic transdifferentiation in porcine liver following lentiviral delivery of human furin-cleavable insulin

Type I diabetes mellitus (TID) results from the autoimmune destruction of the insulin-producing pancreatic β-cells. Gene therapy is one strategy being actively explored to cure TID by affording non-β-cells the ability to secrete insulin in response to physiologic stimuli. In previous studies, we used a novel surgical technique to express furin-cleavable human insulin (INS-FUR) in the livers of streptozotocin (STZ)-diabetic Wistar rats and nonobese diabetic (NOD) mice with the use of the HMD lentiviral vector. Normoglycemia was observed for 500 and 150 days, respectively (experimental end points). Additionally, some endocrine transdifferentiation of the liver, with storage of insulin in granules, and expression of some β-cell transcription factors (eg, Pdx1, Neurod1, Neurog3, Nkx2-2, Pax4) and pancreatic hormones in both studies. The aim of this study was to determine if this novel approach could induce liver to pancreatic transdifferentiation to reverse diabetes in pancreatectomized Westran pigs. Nine pigs were used in the study, however only one pig maintained normal fasting blood glucose levels for the period from 10 to 44 days (experimental end point). This animal was given 2.8 × 10(9) transducing units/kg of the lentiviral vector expressing INS-FUR. A normal intravenous glucose tolerance test was achieved at 30 days. Reverse-transcription polymerase chain reaction analysis of the liver tissue revealed expression of several β-cell transcription factors, including the key factors, Pdx-1 and Neurod1, pancreatic hormones, glucagon, and somatostatin; however, endogenous pig insulin was not expressed. Triple immunofluorescence showed extensive insulin expression, as was previously observed in our studies with rodents. Additionally, a small amount of glucagon and somatostatin protein expression was seen. Collectively, these data indicate that pancreatic transdifferentiation of the liver tissue had occurred. Our data suggest that this regimen may ultimately be used clinically to cure TID, however more work is required to replicate the successful reversal of diabetes in increased numbers of pigs.

Three-dimensional digital visible heart model and myocardial pathological characteristics of fetal single ventricle connected with aortic coarctation

This study aimed to provide data for imaging diagnosis and clinical surgical plans by reconstructing a three-dimensional (3-D) digital visible heart model of single ventricle (SV) connection with aortic coarctation (CoA) and characterizing the myocardial and vascular wall pathological characteristics. Fifteen miscarried fetus cadavers with SV and CoA were selected. Fourteen cardiac specimens were systematically reviewed for segmental anatomy and conventional histological examinations. One fetus cadaver was used to obtain the structural dataset of the fetal body and to reconstruct a 3-D digital visible heart model. Specimen pathological dissection indicated hypertrophic myocardium SV, significant aortic wall thickening, and localized coarctation area elevation. Ten cases of SV with left ventricular morphology displayed a large muscle ridge and solitus normally aligned great arteries. Five cases of SV with right ventricular morphology had coarse, parallel trabeculations and received a common atrioventricular valve. The reconstructed 3-D heart and the main internal structures were realistic, which were beneficial for clinical and image teaching of fetal heart development. The change of characteristics of the myocardium and great vascular wall was obvious and may be the critical cause leading to progressive dysfunction in the postnatal heart.

Concomitant loss of EAF2/U19 and Pten synergistically promotes prostate carcinogenesis in the mouse model

Multiple genetic alterations are associated with prostate carcinogenesis. Tumor-suppressor genes phosphatase and tensin homolog deleted on chromosome 10 (Pten) and androgen upregulated gene 19 (U19), which encodes ELL-associated factor 2 (EAF2), are frequently inactivated or downregulated in advanced prostate cancers. Previous studies showed that EAF2 knockout caused tumors in multiple organs and prostatic intraepithelial neoplasia (PIN) in mice. However, EAF2-knockout mice did not develop prostate cancer even at 2 years of age. To further define the roles of EAF2 in prostate carcinogenesis, we crossed the Pten+/- and EAF2+/- mice in the C57/BL6 background to generate EAF2-/-Pten+/-, Pten+/-, EAF2-/- and wild-type mice. The prostates from virgin male mice with the above four genotypes were analyzed at 7 weeks, 19 weeks and 12 months of age. Concomitant loss of EAF2 function and inactivation of one Pten allele induced spontaneous prostate cancer in 33% of the mice. Prostatic tissues from intact EAF2-/- Pten+/- mice exhibited higher levels of phospho-Akt, -p44/42 and microvessel density. Moreover, phospho-Akt remained high after castration. Consistently, there was a synergistic increase in prostate epithelial proliferation in both intact and castrated EAF2-/-Pten+/- mice. Using laser-capture microdissection coupled with real-time reverse transcription-PCR, we confirmed that co-downregulation of EAF2 and Pten occurred in >50% clinical prostate cancer specimens with Gleason scores of 8-9 (n=11), which is associated with poor prognosis. The above findings together demonstrated synergistic functional interactions and clinical relevance of concurrent EAF2 and Pten downregulation in prostate carcinogenesis.

Determination of mizoribine in human plasma using high-performance liquid chromatography: application to a pharmacokinetic study in Chinese renal transplant recipients

A rapid, simple, and reproducible high-performance liquid chromatographic method (HPLC) was developed and validated for the determination of mizoribine in human plasma using cytarabine as internal standard (IS). The plasma samples of mizoribine were precipitated with 6% perchloric acid. The supernatant was separated on a reversed phase C18 column with a mobile phase of 10 mM KH2PO4 buffer solution (pH 6.3) containing 10 mM perchloric acid using isocratic elution (at flow rate 1.5 mL/min), and detected using an ultraviolet detector at 280 nm. The assay exhibited a linear range of 0.02-10.0 μg/mL for mizoribine in human plasma and the lower limit of quantification was 0.02 μg/mL. The method was statistically validated for linearity, accuracy, precision and selectivity. In addition, the method was successfully applied to estimate the pharmacokinetic parameters of mizoribine in Chinese kidney transplant patients following an oral administration of 100 mg mizoribine (2 Bredinin® 50 mg tablets).

Decreased expression of p38 MAPK mediates protective effects of hydrogen sulfide on hepatic fibrosis

AIM

To investigate the in vitro and in vivo effects of hydrogen sulfide (H2S) on activated hepatic stellate cells (HSCs) and carbon tetrachloride (CCl4)-induced hepatic fibrosis rats. To explore the in vitro and in vivo expression of Phospho-p38, Phospho-Akt and NF-kB in HSCs treated with H2S.

MATERIALS AND METHODS

HSC-T6 cells were incubated and activated with 500 µg/L ferric nitrilotriacetate (Fe-NTA), and then were incubated with NaHS, an H2S-releasing molecule for 6, 12, 24 and 48 h. MTT assay was performed to detect cell viability. Propidium iodide (PI) staining was used to determine cell cycle by flow cytometry. Apoptosis was detected with Annexin-V FITC (fluorescein isothiocyanate) and PI (propidium iodide) double staining. Western blotting was performed to detect protein expressions of Phospho-p38, Phospho-Akt and NF-kB. Hepatic fibrosis model was established by intraperitoneal injection of CCl4 in male Wistar rats, and rats were randomly divided into three groups, including healthy control, rats treated with CCl4 + saline, and rats treated with CCl4 + NaHS. Immunohistochemistry analysis was performed to measure protein expression of Phospho-p38 and Phospho-Akt in rat hepatic samples.

RESULTS

NaHS inhibited the proliferation of Fe-NTA (nitrilotriacetic acid)-induced HSC-T6 cells in a dose-dependent way at 6, 12, 24 and 48 h. NaHS (500 µmol/L) induced G1 phase cell cycle arrest and promoted survival in Fe-NTA-induced HSC-T6 cells. NaHS decreased Phospho-p38 and increased Phospho-Akt expressions in Fe-NTA-induced HSC-T6 cells and CCl4-induced liver fibrosis rats.

CONCLUSIONS

Exogenous H2S inhibits activated HSC-T6 cells and induces cell cycle arrest and apoptosis. Decreased Phospho-p38 and increased Phospho-Akt expressions may mediate the anti-fibrosis effect by exogenous H2S.