Efficient phosphate accumulation in the newly isolated Acinetobacter junii strain LH4.

Phosphate (PO43-) accumulation associated with bacteria contributes to efficient remediation of eutrophic waters and has attracted attention due to its low cost, high removal efficiency and environmental friendliness. In the present study, we isolated six strains from sludge with high concentrations of chemical oxygen demand, total nitrogen and total phosphorus levels. Among them, strain LH4 exhibited the greatest PO43- removal ability. Strain LH4 is typical of Acinetobacter junii based on physiological, biochemical, and molecular analyses and is a PO43--accumulating organism (PAO) based on toluidine blue staining. The strain grew quickly when subjected to aerobic medium after pre-incubation under anaerobic condition, with a maximum OD600 of 1.429 after 8 h and PO43- removal efficiency of 99%. Our data also indicated that this strain preferred utilizing the carbon (C) sources sodium formate and sodium acetate and the nitrogen (N) sources NH4Cl and (NH4)2SO4 over other compounds. To achieve optimal PO43- removal efficiency, a C:N ratio of 5:1, inoculation concentration of 3%, solution pH of 6, incubation temperature of 30 °C, and shaking speed of 100 rpm were recommended for A. junii strain LH4. By incubating this strain with different concentrations of PO43-, we calculated that its relative PO43- removal capacity ranged from 0.67 to 3.84 mg L-1 h-1, ranking in the top three among reported PAOs. Our study provided a new PO43--accumulating bacterial strain that holds promise for remediating eutrophic waters, and its potential for large-scale use warrants further investigation.

A Novel Technique for Correcting Peritoneal Dialysis Catheter Malposition and Blockage.

Methods To investigate the safety and clinical significance of the method described in this study, we focused on 16 peritoneal dialysis patients with peritoneal dialysis (PD) catheter malposition and blockage in whom nonsurgical reposition was ineffective, who received a local incision about 5 cm below hypogastrium PD catheter insertions under local anesthesia. Tissues were separated layer by layer, 1-cm incisions were performed on the peritoneum vertically and conventionally, and then the PD catheters were pulled. Adherent mesentery was separated and the PD catheters were freed and removed sufficiently. PD catheters were introduced into the Dow cavity using large introducing forceps, were loop-ligated and fixed using 3# silk thread, and then the ligation line was sutured to the peritoneum. The tissues were managed layer by layer and the skin was sutured. All patients were followed up for half a year. Results Sixteen cases of refractory PD catheter malposition and blockage were managed successfully, with an operative incision of 3 cm and an operation time of 40±13 minutes. The localized anesthesia was well tolerated, and there were five cases in which lidocaine at 5 mg was added during the operation; postoperative pain was slight and only three patients used analgesics at night. All patients were treated with coagulation hemostasis, and there was no transfusion. No malposition, leakage or blockage was found at follow-up at more than six months. Conclusion It is safe, simple, inexpensive and associated with fewer complications to correct refractory PD catheter malposition and blockage by loop ligature and fixation through a minilaparotomy of inserted hypogastrium PD catheters promptly.

Effect of dimethyl fumarate on rats with chronic pancreatitis.

OBJECTIVE: To discuss the effect of dimethyl fumarate (DMF) on rats with l-arginine induced chronic pancreatitis (CP). METHODS: Male Wistar rats were given DMF treatment (25 mg/kg) by oral lavage method; then Wistar rats were given the intraperitoneal injection of l-arginine for 5 times (250 mg/100 kg, twice per time, each interval of 1 h) for building of CP model. Rats were divided into control group, CP group, DMF group and CP + DMF group. Rats in CP + DMF group were given the oral intragastric administration of DMF (25 mg/kg), while rats in control group and CP group were given the equal volume of normal saline. The weight of rats was evaluated and the intraperitoneal glucose tolerance test was performed (IPGTT, 2 g/kg). The islet of rats was isolated and then flow cytometry was employed to evaluate the quality and activity of islets. Meanwhile, the histology of non-endocrine tissues and levels of myeloperoxidase (MPO) and malondialdehyde (MDA) were detected. RESULTS: Compared with control group, the weight of rats in CP group was significantly reduced at week 2, 4 and 6; the blood glucose significantly increased, AUC increased, the histopathological scores of pancreatic atrophy, acinar injury, edema and cellular infiltration increased, levels of MDA and MPO increased, the islet equivalent and islet activity decreased at 0, 30, 60, 120 and 180 min. Compared with CP group, the weight of rats in CP + DMF group significantly increased at week 2, 4 and 6; the blood glucose significantly decreased, AUC decreased, the histopathological scores of pancreatic atrophy, acinar injury, edema and cellular infiltration decreased, levels of MDA and MPO decreased, the islet equivalent and islet activity increased at 0, 30, 60, 120 and 180 min. CONCLUSIONS: DMF treatment can improve CP induced by l-arginine and islet function in rats.

Protection of centre spin coherence by dynamic nuclear spin polarization in diamond.

We experimentally investigate the protection of electron spin coherence of a nitrogen-vacancy (NV) centre in diamond by dynamic nuclear spin polarization (DNP). The electron spin decoherence of an NV centre is caused by the magnetic field fluctuation of the (13)C nuclear spin bath, which contributes large thermal fluctuation to the centre electron spin when it is in an equilibrium state at room temperature. To address this issue, we continuously transfer the angular momentum from electron spin to nuclear spins, and pump the nuclear spin bath to a polarized state under the Hartmann-Hahn condition. The bath polarization effect is verified by the observation of prolongation of the electron spin coherence time (T). Optimal conditions for the DNP process, including the pumping pulse duration and repeat numbers, are proposed by numerical simulation and confirmed by experiment. We also studied the depolarization effect of laser pulses. Our results provide a new route for quantum information processing and quantum simulation using the polarized nuclear spin bath.

Development of nanofibrous scaffolds for vascular tissue engineering.

Small-diameter vascular grafts can easily lead to thrombosis and intimal hyperplasia. So the rate of the long-term patency is not satisfactory. Scaffolds that can support the growth of cells and remain stable and passable in vivo are in great demand. Vascular scaffolds were fabricated by electrospinning RGD-recombinant spider silk protein (pNSR32), polycaprolactone (PCL) and chitosan (CS). In addition, the cytocompatibility, the stability and the patency of scaffolds in vivo were studied. The results demonstrated that Sprague-Dawley rat aortic endothelial cells (SDRAECs) could highly enhanced adhesion and proliferation, together with increasing stress of fiber formation, and intensive biological function (the expression of PECAM-1 and vWF, the secretion of NO), in the pNSR32/PCL/CS scaffolds, compared with in the pNSR32/PCL and PCL scaffolds. The cell cycle studies of SDRAECs also revealed that the scaffolds promoted the cells to enter the stage of divisional proliferation. Furthermore, pNSR32/PCL/CS scaffolds could support the growth of cells under physiologic conditions and are able to maintain the structural integrity and patency for at least 8 weeks in a SD rat abdominal aortic defect model.

Effect of oxygen concentration in gas phase on sporulation and individual ganoderic acids accumulation in liquid static culture of Ganoderma lucidum.

Effects of oxygen concentration within 21-100% in gaseous phase on the morphology and ganoderic acids (GAs) production by Ganoderma lucidum in liquid static culture were studied. A higher oxygen concentration increased individual GAs production, and more spores and higher total GA content were obtained at an oxygen level of 80%.

Impact of oxygen level in gaseous phase on gene transcription and ganoderic acid biosynthesis in liquid static cultures of Ganoderma lucidum.

Liquid static cultivation of Ganoderma lucidum was previously found to be very efficient for improving the production of its valuable antitumor compound ganoderic acid (GA) (Fang and Zhong in Biotechnol Prog 18:51-54, 2002). In this work, effects of oxygen concentration within the range of 21-100% (v/v) in the gaseous phase on the mycelia growth, GA production, and gene transcription of key enzymes for GA biosynthesis in liquid static cultures of G. lucidum were investigated. A high cell density of 29.8 +/- 1.7 g/l DW and total GA production of 1427.2 +/- 74.2 mg/l were obtained under an optimal gaseous O(2) level of 80%. The expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase, squalene synthase and lanosterol synthase genes of GA biosynthetic pathway as detected by quantitative real-time PCR was also affected by the gaseous oxygen concentration in the liquid static culture. H(2)O(2) was generated as reactive oxygen species in response to high oxygen concentrations in the gas phase, and it seemed to be involved in the regulation of GA biosynthesis. The information obtained in this study provided an insight into the role of gaseous O(2) in the GA production and it will be helpful for further enhancing its productivity.

[Pulmonary nocardiosis in immunocompromised host: report of 2 cases and review of the literature].

OBJECTIVE: To investigate the clinical, imaging and pathogenic features of pulmonary nocardiosis and the drug resistance of Nocardia. METHODS: The clinical and radiological data of 2 cases of pulmonary nocardiosis in this hospital were presented, and 32 cases reported in the Chinese literature since 1982 were reviewed. RESULTS: Among the 34 cases of Nocardia infections, there were 26 cases of pulmonary nocardiosis, and 4 of whom died. Multiple organ infection occurred in 11 patients, including 7 with pulmonary and skin infections, 3 with pulmonary, skin and intracranial infections, and 1 with pulmonary and intracranial infections. All patients with pulmonary nocardiosis had cough. Of the 34 cases, 27 had fever, including intermittent fever in 5, and sustained fever in 22 cases. Of the 11 cases of pulmonary nocardiosis complicated with skin or intracranial dissemination, 8 patients were immunocompromised and 3 were immunocompetent (chi(2) = 2.08, P > 0.05). Three cases died in the immunocompromised group and 1 died in the immunocompetent group. Nocardia asteroides was identified in 14 cases, Nocardia brasiliensis in 4 cases, and the other 8 were not classified. In the patients with complicated skin or intracranial infections, 8 were caused by Nocardia asteroids, and 2 were caused by Nocardia brasiliensis. Chest X-ray or CT imaging of the lungs showed pleural effusion in 8, masses in 7, infiltrates in 6, cavities in 6, and nodular lesions in 5 cases. Antimicrobial susceptibility testing showed that Nocardia was sensitive to sulfonamide, amikacin, cefotaxime, ceftriaxone, minocycline, fluoroquinolones, and linezolid. CONCLUSIONS: Immunosuppression is the most important predisposing factor for pulmonary nocardiosis. The most common pathogenic bacterium is Nocardia asteroids, which is frequently associated with disseminated lesions. The radiographic abnormalities of the lung show pleural effusion, masses, infiltration or cavity. With the increasing rate of resistance of Nocardia to the sulfonamide, the combination of antibiotic regimen according to susceptibility testing needs to be considered. Poor outcome is mostly found in immunocompromised hosts.

[The effect of recombinant panton-valentine leukocidin on the production of cytokines by human alveolar macrophages].

OBJECTIVE: To investigate the effect of recombinant panton-valentine leukocidin (rPVL) on the regulation of human alveolar macrophage CD14 and IL-10 and TNF-alpha. METHODS: Human alveolar macrophages (AM) were purified and cultured from bronchoalveolar lavage fluid. Each sample was divided into groups according to different concentrations and exposure times of rPVL. Semi-quantitative RT-PCR was used to evaluate the CD14 mRNA levels and Double-antibody-sandwich-ELISA was used to measure the IL-10 and TNF-alpha levels in AM cultures. RESULTS: CD14 mRNA decreased after rPVL treatment in time-and concentration dependent manners. There were no statistically significant differences in CD14 mRNA among the blank control groups (F = 1.708, P > 0.05). CD14 mRNA in the T6N10 group and the T6N100 group( T = time in hours, N = concentration of rPVL/nmol/L) decreased as compared to the T6N0 group (t = 4.132, 6.818, both P < 0.001), and that in the T24N10 group and the T24N100 group also decreased as compared to the T24N0 group (t = 7.401, 11.415, both P < 0.001), indicating that the expression of CD14 was downregulated by rPVL treatment. There were also statistically significant differences in CD14 mRNA between T6N10 and T24N10 groups, T6N100 and T24N100 groups (t = 4.692, 6.019, both P < 0.001), T6N10 and T6N100 groups, T24N10 and T24N100 groups (t = 2.686, 4.014, P < 0.01 respectively), indicating that the expression of CD14 decreased as the treatment time and the concentration of rPVL increased. The IL-10 concentrations of the T24N10 and T24N100 groups increased as compared to the T24N0 group (t = 4.036, 3.941, both P < 0.01) in time-dependent and concentration-dependent manners with rPVL treatment. The TNF-alpha concentration of the T24N10 group decreased while that of the T24N100 group increased as compared to the T24N0 group (t = 2. 824, 8. 468, both P < 0.01, respectively), indicating that a lower concentration of rPVL inhibited TNF-alpha release while a higher concentration of rPVL induced release of TNF-alpha. CONCLUSION: The results suggest that rPVL could reduce the expression of CD14 and induce disordered release of anti-inflammatory and proinflammatory cytokines by AMs, which may be one of the important mechanisms underlying the high mortality of infection with PVL-positive Staphylococcus aureus.

[Study on construct and expression of synthetic genes encoding spider dragline silk in Escherichia coli].

Dragline spider silk produced from Nephilia clavipes major ampullate is a natural fibrous protein with specific mechanical properties such as high tensile strength and elasticity. Synthetic gene monomer encoding recombinant spider silk protein, based on the known repetitive protein sequence and partial cDNA sequence of dragline silk, was constructed and expressed. DNA monomer sequences were multimerized to encode high molecular weight synthetic spider silks using a "head-to-tail" construction strategy. Multimer was cloned into pET30a(+), a prokaryotic high potency expression vector, and induced with IPTG. The protein from 8-unit repeat was produced in Escherichia coli at levels up to 20 mg/L. The protein was easily purified with high recovery by using an metal ion affinity chromatography and purity was over 90%. The results of SDS-PAGE and Western blot suggested that the mass of the expression product was about 37 kD. This value and amino acid analysis were consistent with those of theoretic calculation.

[Development of the chip system for measurement of red blood cell rheology].

We have developed a novel silicon microchannel system for the research of the red blood cell rheology and deformation. Recurring to many kinds of information technologies and advanced test means such as the electronic microscope, the image acquisition system and the computer processing system and by using the up-to-date Micro Electro Mechanical System (MEMS) technology, a new measuring system of red bood cell deformation is designed based on the chip and a model using the silicon microchannel to simulate capillary vessel network. It provides a real-time collection and anaysis of data which include image, speed, flow parameter, and so on. It provides printing, storage of the analysis results and patients' database management.