Isolation and genomic characterization of a novel Autographiviridae bacteriophage IME184 with lytic activity against Klebsiella pneumoniae

Klebsiella pneumoniae, a multidrug resistant bacterium that causes nosocomial infections including septicemia, pneumonia etc. Bacteriophages are potential antimicrobial agents for the treatment of antibiotic resistant bacteria. In this study, a novel bacteriophage IME184, was isolated from hospital sewage against clinical multi-drug resistant Klebsiella pneumoniae. Transmission electron microscopy and genomic characterization exhibited this phage belongs to the Molineuxvirinae genus, Autographiviridae family. Phage IME184 possessed a double-stranded DNA genome composed of 44,598 bp with a GC content of 50.3%. The phage genome encodes 57 open reading frames, out of 26 are hypothetical proteins while 31 had assigned putative functions. No tRNA, virulence related or antibiotic resistance genes were found in phage genome. Comparative genomic analysis showed that phage IME184 has 94% similarity with genomic sequence of Klebsiella phage K1-ULIP33 (MK380014.1). Multiplicity of infection, one step growth curve and host range of phage were also measured. According to findings, Phage IME184 is a promising biological agent that infects Klebsiella pneumoniae and can be used in future phage therapies.

Evaluation of Novel Tranexamic Acid/Montmorillonite Intercalation Composite, as a New Type of Hemostatic Material

Radiation enteritis-clinically manifested as diarrhea, intestinal bleeding, and so on-is frequently caused when the body is exposed to radiation or radiotherapy because the intestine is radiation-sensitive as an abdominal organ. Therefore, strategies to modulate intestinal hemostasis had inspired an important research trend in the process of preventing and treating radiation enteritis. Based on the structural characteristics of montmorillonite (MMT) and the hemostatic drug tranexamic acid (TXA) which was used clinically to treat enteritis, the tranexamic acid-montmorillonite composite material (TXA-MMT) was prepared through intercalation composite technology. According to the analysis of FTIR, XRD, TG-DTG, SEM, and XRF, the prepared TXA-MMT was verified that tranexamic acid could intercalate into layers of montmorillonite. To evaluate the biocompatibility, two experiments were conducted by in vitro hemolysis and in vitro cytotoxicity experiments and results showed that TXA-MMT exhibited good visible biocompatibility. Activated partial thromboplastin time, prothrombin time, and in vitro clotting time were adopted to determine the hemostatic effect of TXA-MMT. Compared with other groups, TXA-MMT revealed a significant decrease in clotting time variations, APTT, and PT. In addition, to investigate the preventive effect of TXA-MMT by the intervention of radiation enteritis mice, inflammatory factors IL-1β, IL-6, and TNF-α and the content of endotoxin in the serum of mice were detected. It demonstrated that TXA-MMT reduced the levels of these factors. Besides, the expression and the pathological changes of the small intestine tissue of mice were relieved. Our findings suggests that TXA-MMT as a promising intercalation composite has a great potential for application in the field of intestinal hemostasis.

Microbial hydrogen economy alleviates colitis by reprogramming colonocyte metabolism and reinforcing intestinal barrier

With the rapid development and high therapeutic efficiency and biosafety of gas-involving theranostics, hydrogen medicine has been particularly outstanding because hydrogen gas (H₂), a microbial-derived gas, has potent anti-oxidative, anti-apoptotic, and anti-inflammatory activities in many disease models. Studies have suggested that H₂-enriched saline/water alleviates colitis in murine models; however, the underlying mechanism remains poorly understood. Despite evidence demonstrating the importance of the microbial hydrogen economy, which reflects the balance between H₂-producing (hydrogenogenic) and H₂-utilizing (hydrogenotrophic) microbes in maintaining colonic mucosal ecosystems, minimal efforts have been exerted to manipulate relevant H₂-microbe interactions for colonic health. Consistent with previous studies, we found that administration of hydrogen-rich saline (HS) ameliorated dextran sulfate sodium-induced acute colitis in a mouse model. Furthermore, we demonstrated that HS administration can increase the abundance of intestinal-specific short-chain fatty acid (SCFA)-producing bacteria and SCFA production, thereby activating the intracellular butyrate sensor peroxisome proliferator-activated receptor γ signaling and decreasing the epithelial expression of Nos2, consequently promoting the recovery of the colonic anaerobic environment. Our results also indicated that HS administration ameliorated disrupted intestinal barrier functions by modulating specific mucosa-associated mucolytic bacteria, leading to substantial inhibition of opportunistic pathogenic Escherichia coli expansion as well as a significant increase in the expression of interepithelial tight junction proteins and a decrease in intestinal barrier permeability in mice with colitis. Exogenous H₂ reprograms colonocyte metabolism by regulating the H₂-gut microbiota-SCFAs axis and strengthens the intestinal barrier by modulating specific mucosa-associated mucolytic bacteria, wherein improved microbial hydrogen economy alleviates colitis.

Experimental investigation on dynamic characteristics and strengthening mechanism of laser-induced cavitation bubbles

The dynamic features of nanosecond laser-induced cavitation bubbles near the light alloy boundary were investigated with the high-speed photography. The shock-waves and the dynamic characteristics of the cavitation bubbles generated by the laser were detected using the hydrophone. The dynamic features and strengthening mechanism of cavitation bubbles were studied. The strengthening mechanisms of cavitation bubble were discussed when the relative distance parameter γ was within the range of 0.5-2.5. It showed that the strengthening mechanisms caused by liquid jet or shock-waves depended on γ much. The research results provided a new strengthening method based on laser-induced cavitation shotless peening (CSP).

Association of vitamin D receptor gene polymorphisms with pancreatic cancer: A pilot study in a North China Population

Polymorphisms of the vitamin D receptor (VDR) gene may be a risk factor for pancreatic cancer (PC). We investigated the association of two single-nucleotide polymorphisms (SNPs) of the VDR gene with PC in age- and gender-matched patients and controls. PC (n=91) and healthy control (n=80) samples were genotyped for the FokI (rs2228570) and BsmI (rs1544410) polymorphisms using the PCR and restriction fragment length polymorphism (PCR-RFLP) method. Chi-square analysis was used to test for the overall association of VDR genotype with disease. There was a significant difference in the frequency of genotype FF between the PC patients and controls (P^trend=0.009); however, the difference in frequency of genotype BB between the two groups was not significant (P^trend=0.082). The difference between FF and Ff/ff frequency was significant (P=0.002). The two high-risk genotypes were ffbb and Ffbb, with an 11.66- and 6.42-fold increased risk of PC, respectively. VDR gene polymorphisms were important for the development of PC in this study population; however, further exploration of these findings and their implications are required.

Treatment of distal femoral nonunion and delayed union by using a retrograde intramedullary interlocking nail

OBJECTIVE

To analyze the causes of distal femoral nonunion and delayed union and assess the outcome of the corresponding treatment, retrograde intramedullary interlocking nail (RIIN).

METHODS

From June 1995 to December 1998, 15 patients (9 males and 6 females) with distal femoral nonunion and delayed union were treated with RIIN. The average age of the patients was 34.5 years (23-46 years). Bone grafting was performed in 10 patients, closed reaming was done in the other 5 patients. Correction osteotomy was performed in 2 patients, and intra-articular release of knee adhesion in 11 patients. X-ray examination and knee society clinical rating system (KSS) were used to evaluate the results.

RESULTS

All fractures were followed up for at least 9 months with average follow-up duration of 14.5 months (9-33 months). Solid union was documented in all patients at 6.4 months on average. There were no infections or malunions in this series. Based on the final follow-up data, acceptable functional range of motion (ROM) of over 90 degrees was achieved in most patients. The average ROM was 93.5 degrees with significant improvement of 28 degrees (42.7%, P<0.05) compared with the preoperative ROM. The average knee score was 96. Excellent ROM emerged in 13 patients. The knee function score was 90.5 on average.

CONCLUSIONS

The main causes of distal femoral nonunion and delayed union are improper indications and improper use of the implants. RIIN is an effective alternative for treatment of distal femoral nonunion and delayed union because it can provide a stable and reliable fixation which is beneficial for early functional exercise of knee. Bone grafting, closed reaming and intra-articular release of knee adhesion should be considered in order to enhance the bone healing and improve ROM and the knee function.

The interaction of trichosanthin with supported phospholipid membranes studied by surface plasmon resonance

Trichosanthin (TCS) is a toxic protein isolated from a Chinese herbal medicine, the root tuber of Trichosanthes kirilowii Maximowicz of the Curcurbitaceae family. It is now used in China to terminate early and mid-trimester pregnancies. The ribosome inactivating property is thought to be account for its toxicity; it can inactivate the eukaryotic ribosome through its RNA N-glycosidase activity. The interactions of TCS with biological membrane is thought to be essential for its physiological effect, for it must get across the membrane before it can enter the cytoplasm and exert its RIP function. In the present work, the interaction of TCS with supported phospholipid monolayers is studied by surface plasmon resonance. The results show that electrostatic forces dominate the interaction between TCS and negatively charged phospholipid containing membranes under acid condition and that both the pH value and the ionic strength can influence its binding. It is proposed that, besides electrostatic forces, hydrophobic interaction may also be involved in the binding process.

[Release character of phosphorus from the sediments of east Lake, Wuhan]

Effects of environmental factors on the release of phosphorus were studied at laboratory simulated test. The relationship between the different forms of phosphorus in sediments and the quantity of releasing phosphorus was studied at the same time. Results showed that the rates of phosphorus release from the sediment increased with rising the temperature of disturbing the overlying water. The content of phosphorus release from the sediment reached the lowest level when pH value was 7.4, high pH or low pH increased the rates of phosphorus release from the sediment. In anaerobic, the release rates of phosphorus was 30 times as much as in aerobic. Research also showed that different chemical forms of phosphorus in sediments were related to the quantity of phosphorus released from the sediments in varying degrees. The dissolved phosphorus and Fe binding phosphorus in sediments played the most important roles (r > 0.90, P < 0.01).

Quantitative determination of surface concentration of human apolipoprotein H with capillary electrophoresis

The phospholipid monolayer at an air/water interface is widely used to mimic the biological membrane. The dynamic process of the protein or peptide interacting with lipid molecules can be reflected in the change in surface pressure of the monolayer. But the conventional method used to measure the surface pressure change gives results that cannot easily be correlated with the contribution of a single protein molecule. Previously, measuring the surface concentration of the protein molecules at the air/water interface has required the protein to be labeled with radioactivity or fluorescence. Here, a new method using capillary electrophoresis is introduced to measure the surface concentration of the protein. The results show at least two advantages of the new method: The numerical results of protein concentration can be obtained in a more precise and rapid way; and there is no need to label the protein sample or to build a special monolayer setup.

Trimeric ring-like structure of ArsA ATPase

ArsA protein is the soluble subunit of the Ars anion pump in the Escherichia coli membrane which extrudes arsenite or antimonite from the cytoplasm. The molecular weight of the subunit is 63 kDa. In the cell it hydrolyzes ATP, and the energy released is used by the membrane-bound subunit ArsB to transport the substrates across the membrane. We have obtained two-dimensional crystals of ArsA in the presence of arsenite on negatively-charged lipid monolayer composed of DMPS and DOPC. These crystals have been studied using electron microscopy of negatively-stained specimens followed by image processing. The projection map obtained at 2.4 nm resolution reveals a ring-like structure with threefold symmetry. Many molecular assemblies with the same ring-shape and dimensions were also seen dispersed on electron microscopy grids, prepared directly from purified ArsA protein solution. Size-exclusion chromatography of the protein sample with arsenite present revealed that the majority of the protein particles in solution have a molecular weight of about 180 kDa. Based on these experiments, we conclude that in solution the ArsA ATPase with substrate bound is mainly in a trimeric form.

Pentameric two-dimensional crystallization of rabbit C-reactive protein on lipid monolayers

As a member of the pentraxin family, C-reactive protein plays various roles in the nonspecific immunity of animals. Though soluble, C-reactive protein always functions on membranes. In order to study the structure of the membrane-bound protein and the reaction between protein and membranes, two-dimensional (2D) crystallization of rabbit C-reactive protein on lipid monolayers was performed. The 2D crystals composed of pentameric proteins were obtained on lipid monolayers by specific adsorption for the first time. The projection map at 26-A resolution is presented, which exhibits P2 symmetry with lattice parameters a = 158(+/-3) A, b = 92(+/-1) A, and gamma = 107(+/-1) degrees. The current work may give a basis for the further study on the structure of complexes made up of C-reactive protein with its functional binding molecules on membranes.

Intrinsic fluorescence study of the interaction of human apolipoprotein H with phospholipid vesicles

Apolipoprotein H (ApoH) is a plasma glycoprotein with its in vivo physiological and pathogenic roles being closely related to its interaction with negatively charged membranes. In this paper, the interaction of ApoH with phospholipid vesicles was characterized by (i) detecting the wavelength shift of the fluorescence spectrum of ApoH and (ii) measuring the fluorescence quenching extent of ApoH by the membrane resident quencher 1-palmitoyl-2-stearoyl-(5-doxyl)-sn-glycero-3-phosphocholine (DPC). The observed blue shift upon addition of DMPG vesicles indicated that the tryptophan residues of ApoH moved from a polar to a nonpolar environment. The insertion ability of ApoH into PG-containing vesicles did not depend on the PG content in a stoichiometric way as did the blue shift, indicating that the negatively charged DMPG does not serve as a specific binding site but rather provides a suitable microenvironment for ApoH interaction. The finding that the detachment effect of cations on the blue shift is remarkably different from that on the quenching extent suggests that ApoH is capable of existing in two different conformations when membrane-bound.

The C domain of HIV-1 gp41 binds the putative cellular receptor protein P62

OBJECTIVE

To characterize the binding of gp41 with the putative receptor protein P62.

DESIGN

HIV-1 gp41 binds several cellular proteins by two binding sites, one of which has been shown to bind to a putative receptor protein P45 (45 kDa). Based on this, an attempt was made to determine the relationship between the two binding sites and P62 (62 kDa).

METHODS

Using surface plasmon resonance (SPR) measurement, the interaction was measured between recombinant soluble gp41 (rsgp41, Env aa539-684) and protein P62. Inhibition of this interaction was attempted by the use of synthetic peptides (P1, aa583-599; P2, aa646-674) corresponding to the two binding sites in gp41. In addition, the direct binding of P62 to peptide P2 was examined in an enzyme-linked immunosorbent assay.

RESULTS

Using SPR measurement, the interaction between P62 and rsgp41 was confirmed, and the interaction was found to be inhibited by only the synthetic peptide P2 sequence that corresponds to the C domain of gp41; neither P1 nor a control peptide inhibited the interaction. Moreover, like rsgp41, P2 was able to bind P62 whereas P1 and another recombinant gp41 (aa567-648 that does not include the C domain) were not.

CONCLUSIONS

P62 bound rsgp41 and the synthetic peptide P2. This interaction could be inhibited only by P2. These results indicate that the C domain of HIV-1 gp41 binds P62.

[Determination of composition of electronic material by fundamental parameter method of XRF]

The fundamental parameters (FP) method of XRF in determination of the composition of electronic ceramic materials is studied. The fundamental parameters needed in calculation are developed by math calculation and the program is developed in C language. The method can also be used in determination of the composition of alloy. Some samples are analysed by this method and the relative derivation is less than 3%.