Strain Wood Research Articles

Kinetics of morphofunctional changes in the center of inflammation of pulmonary tissue caused by staphylococcus aureus

In three experimental series of experimental animals caused by inflammation model with a standard strain of Staphylococcus aureus. (Strain WOOD -46). Held control of the morphological and functional changes in the lung tissue at different times from the beginning of the introduction of Staphylococcus aureus. The histological method was used. The observations indicate a dose-dependent morphological changes in the lung tissue with inflammation caused by various doses of the standard Staphylococcus aureus.

Experimental investigation of the compressive behaviour of GFRP wrapped spruce-pine-fir square timber columns

An experimental program investigating the behaviour of square timber columns wrapped with fibre-reinforced polymer (FRP) composites under compression loading was undertaken. A total of six unwrapped control specimens and thirty glass FRP (GFRP) specimens were tested with emphasis on characterizing the altered stress–strain behaviour and examining the failure modes. The effects of varying GFRP composite configurations (fibre direction, thickness) were investigated, and each specimen was dissected after testing to study how the wood failed. Test results showed that with proper thickness, FRP wrapping can prevent undesirable splitting and shearing modes of failure in the wood and negate the influence of naturally occurring wood defects to induce crushing in the wood fibres. The crushing mode of failure promoted by FRP wrapping contributed to significantly improved post-peak behaviour with FRP wrapped specimens sustaining up to 61% of their peak compressive strength at a strain of 0.04 mm/mm compared to 41% in the control specimens. The reinforced specimens were on average capable of dissipating between 1.35 and 1.68 times more energy compared to the control group. It is clear from the test results that FRP wrapping can help the overall behaviour of wood members become more reliable and uniform. In particular, the consistency in the post-peak stress–strain behaviour and wood failure is conducive to the development of an analytical model. The improved post-peak behaviour could also benefit wood members in flexure and wood structures subjected to extreme loads such as earthquakes and blast loads.

1202. Subinhibitory Concentrations of Omadacycline Inhibit Staphylococcus aureus Hemolytic Activity in Vitro

BackgroundIn animal models of Staphylococcus aureus infection, α-hemolysin has been shown to be a key virulence factor. Treatment of S. aureus with subinhibitory levels of protein synthesis inhibitors can decrease α-hemolysin expression. Omadacycline, a novel aminomethylcycline antibiotic in the tetracycline class of bacterial protein biosynthesis inhibitors, is approved in the United States for treatment of community-acquired bacterial pneumonia (CABP) and acute bacterial skin and skin structure infections (ABSSSI) in adults. This study was performed to determine the durability of inhibition and effect of subinhibitory concentrations of omadacycline on S. aureus hemolytic activity.MethodsAll experiments used the methicillin-sensitive S. aureus strain Wood 46 (ATCC 10832), a laboratory strain known to secrete high levels of α-hemolysin. Minimum inhibitory concentrations (MICs) of omadacycline and comparator antibiotics (tetracycline, cephalothin, clindamycin, vancomycin, linezolid) were determined. Growth of S. aureus with all antibiotics was determined and the percentage of hemolysis assayed. “Washout” experiments were performed with omadacycline only.Results S. aureus cultures treated with 1/2 or 1/4 the MIC of omadacycline for 4 hours showed hemolysis units/108 CFU of 47% and 59% of vehicle-treated cultures, respectively (Fig. 1A, 1B). In washout experiments, treatment with as little as 1/4 the MIC of omadacycline for 1 hour decreased the hemolysis units/108 CFU by 60% for 4 hours following removal of the drug (Table 1).Figure 1 Table 1 ConclusionOmadacycline inhibited S. aureus hemolytic activity in vitro at subinhibitory concentrations and inhibition was maintained for ≥ 4 hours after removal of extracellular drug (Fig. 2). The suppression of virulence factors throughout the approved omadacycline dosing interval, in addition to the in vitro potency of omadacycline, may contribute to the efficacy of omadacycline for ABSSSI and CABP due to virulent S. aureus. This finding may apply to other organisms and other virulence factors that require new protein synthesis to establish disease.Figure 2 DisclosuresAlisa W. Serio, PhD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder) S. Ken Tanaka, PhD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder) Kelly Wright, PharmD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder) Lynne Garrity-Ryan, PhD, Paratek Pharmaceuticals, Inc. (Employee, Shareholder)

Dynamic Mechanical Properties of Russian Pinus sylvestris var. mongolica Litv: Experimental and Numerical Simulation

With the Split Hopkinson Pressure Bar (SHPB) experiment and numerical simulation on Russian Pinus sylvestris var. mongolica Litv carried out, the dynamic mechanical properties of the pine wood at high strain rates were researched, and the relevant constitutive models was analyzed. The experiment results suggested that the dynamic mechanical properties of the pine wood were affected by strain rates and wood directions. The stress-strain relationship was mainly influenced by wood directions, but the initial yield stress was related to strain rates and wood directions. When the load was along the straight grain direction, fracture behaviors were caused by shear damage and fiber tensile fracture. The specimens were broken into ‘crushed’ pieces because of fiber and lignin separation, and fiber kink. However, it was chief role for the fracture in transverse grain direction that failure cracks grew down fiber. The dynamic responses described with model based on improved Hashin failure criterion were consistent with actual results, compared with model based on the Hill yield criterion. Related research work provides a certain reference for the related problems research and engineering practice application of Russian Pinus sylvestris var. mongolica Litv.

Staphylococcus aureus‐induced complement activation promotes tissue factor‐mediated coagulation

Background There is extensive cross-talk between the complement system, the Toll-like receptors (TLRs), and hemostasis. Consumptive coagulopathy is a hallmark of sepsis, and is often mediated through increased tissue factor (TF) expression. Objectives To study the relative roles of complement, TLRs and TF in Staphylococcus aureus-induced coagulation. Methods Lepirudin-anticoagulated human whole blood was incubated with the three S. aureus strains Cowan, Wood, and Newman. C3 was inhibited with compstatin, C5 with eculizumab, C5a receptor 1 (C5aR1) and activated factor XII with peptide inhibitors, CD14, TLR2 and TF with neutralizing antibodies, and TLR4 with eritoran. Complement activation was measured by ELISA. Coagulation was measured according to prothrombin fragment 1 + 2 (PTF1 + 2 ) determined with ELISA, and TF mRNA, monocyte surface expression and functional activity were measured with quantitative PCR, flow cytometry, and ELISA, respectively. Results All three strains generated substantial and statistically significant amounts of C5a, terminal complement complex, PTF1 + 2 , and TF mRNA, and showed substantial TF surface expression on monocytes and TF functional activity. Inhibition of C5 cleavage most efficiently and significantly inhibited all six markers in strains Cowan and Wood, and five markers in Newman. The effect of complement inhibition was shown to be completely dependent on C5aR1. The C5 blocking effect was equally potentiated when combined with blocking of CD14 or TLR2, but not TLR4. TF blocking significantly reduced PTF1 + 2 levels to baseline levels. Conclusions S. aureus-induced coagulation in human whole blood was mainly attributable to C5a-induced mRNA upregulation, monocyte TF expression, and plasma TF activity, thus underscoring complement as a key player in S. aureus-induced coagulation.

Molecular basis of surface anchored protein A deficiency in the Staphylococcus aureus strain Wood 46.

Protein A in Staphylococcus aureus is encoded by the spa (staphylococcal protein A) gene and binds to immunoglobulin (Ig). The S. aureus strain Wood 46 has been variously reported as protein A-deficient and/or spa negative and used as a control in animal models of staphylococcal infections. The results of this study indicate that Wood 46 has normal spa expression but transcribes very low levels of the srtA gene which encodes the sortase A (SrtA) enzyme. This is consistent with unique mutations in the srtA promoter. In this study, a low level of sortase A explains deficient anchoring of proteins with an LPXTG motif, such as protein A, fibrinogen-binding protein and fibronectin-binding proteins A and B on to the peptidoglycan cell wall. The activity of secreted protein A is an important consideration for use of Wood 46 in functional experiments and animal models.

Complete Genome Sequence of Staphylococcus aureus Strain Wood 46.

ABSTRACTHere, we report the first complete genome sequence of the Staphylococcus aureus strain Wood 46. Wood 46 has played an important role in understanding the virulence and pathogenesis of S. aureus infections. This report will assist efforts in vaccine development against methicillin-resistant S. aureus (MRSA) infections.

Strain distribution, growth eccentricity, and tension wood distribution in the plagiotropic and orthotropic branches of Koelreuteria henryi Dummer

With the diversified distribution of growth strain and tension wood, Koelreuteria henryi branches function in a different way from the trunk in maintaining the tree architecture. The tree branches, as well as trunks, function in keeping tree biomechanical equilibrium; however, researches regarding the reorientation of branches have received less attention than those of trunks. The presented paper aims to discriminate the biomechanical behavior of branches from leaning trunks. We thus investigated the development of growth strains, distribution of tension wood, and eccentricity on the branchwood of Koelreuteria henryi. The results revealed the unusual distribution of released growth strain and tension wood as well as growth eccentricity. The growth strain parameter showed seasonal changes, possibly due to the maturation of the secondary cell wall. Both the upper and the lower sides of the plagiotropic branches exhibited either contractive or extensive growth strains, whereas the orthotropic branches exhibited mostly contractive strains on the both sides, which implied different physiological functions of the two branch types. The tension wood arcs may occur in any direction of the branchwood which is different from the inclined trunk with tension wood on the upper side, suggesting dynamic adjustment in branch reorientation. In contrast to trunks, the hypotrophic eccentric growth in branches functioned in obstructing upward movement and even facilitates downward movement, probably because of the dissociation between tension wood and eccentric growth. Diversified growth strain and tension wood distribution on the branches may reflect the individual biomechanical requirements for each branch depending on the environmental factors, possibly gravitropic and phototropic stimuli.

Characterization of Maple and Ash Material Properties as a Function of Wood Density for Bat/Ball Impact Modeling in LS-DYNA

Finite element models of wood baseball bats are a valuable tool to explore the relationship between bat profile and bat durability. However, for such finite element models to be credible, the material models must capture the mechanical response of the wood under consideration. In the current research, a comprehensive experimental program was conducted to characterize the mechanical behavior of maple and ash woods for the range of densities used to make major-league quality baseball bats. The test program included (1) four-point bend testing to determine elastic moduli and strength and (2) Charpy testing to determine strain to failure as a function of strain rate and wood density. The material parameters were subsequently calibrated by completing finite element simulations of the Charpy tests in LS-DYNA using the MAT_WOOD material model. This paper describes the experimental characterization program used to determine material parameters of maple and ash wood species for use in finite element simulations of wood baseball bats.

Combined Inhibition of Complement and CD14 Efficiently Attenuated the Inflammatory Response Induced byStaphylococcus aureusin a Human Whole Blood Model

The complement and TLR systems are activated in sepsis, contributing to an unfavorable inflammatory "storm." Combined inhibition of these systems has been documented to efficiently attenuate the inflammatory responses induced by Gram-negative bacteria. In this study, we hypothesized that the combined inhibition would attenuate the inflammatory responses induced by Gram-positive bacteria. Staphylococcus aureus bacteria (strains Cowan and Wood), as well as S. aureus cell wall lipoteichoic acid (LTA), were incubated in thrombin-inhibited human whole blood. Complement was inhibited at the level of C3 and C5, and the TLRs by inhibiting CD14 and TLR2. Thirty-four inflammatory markers were measured by multiplex technology and flow cytometry. Thirteen markers increased significantly in response to Cowan and Wood, and 12 in response to LTA. Combined inhibition with the C3 inhibitor compstatin and the anti-CD14 Ab 18D11 significantly reduced 92 (Cowan, LTA) and 85% (Wood) of these markers. Compstatin alone significantly reduced 54 (Cowan), 38 (Wood), and 83% (LTA), whereas anti-CD14 alone significantly reduced 23, 15, and 67%, respectively. Further experiments showed that the effects of complement inhibition were mainly due to inhibition of C5a interaction with the C5a receptor. The effects on inhibiting CD14 and TLR2 were similar. The combined regimen was more efficient toward the bacterial effects than either complement or anti-CD14 inhibition alone. Complement was responsible for activation of and phagocytosis by both granulocytes and monocytes. Disrupting upstream recognition by inhibiting complement and CD14 efficiently attenuated S. aureus-induced inflammation and might be a promising treatment in both Gram-negative and Gram-positive sepsis.

Compare on the Main Physical and Mechanical Properties of Two Bamboo Particle Boards

The main physical and mechanical properties of the ordinary and bamboo mat enhancing bamboo particle board (for short EBPB) were detected and analysed through the Resistance Strain Monitor and wood mechnical test machine. The results proved that the tensile and bend deformation of two kinds of bamboo partical board(for short BPB) increased nonlinearly with the load increasing. The greatest tensile and bend load increased respectively 66% and 56%, and in the tensile and bend deformations, decreased respectively 21% and 20% EBPB than the ordimary bamboo particle board(for short OBPB). The main physical and mechnical properties of the EBPB exceeded markedly OBPB, which showed the bamboo mat could increased evidently the physical and mechnical properties of BPB.

More than One Tandem Repeat Domain of the Extracellular Adherence Protein ofStaphylococcus aureusIs Required for Aggregation, Adherence, and Host Cell Invasion but Not for Leukocyte Activation

The extracellular adherence protein (Eap) is a multifunctional Staphylococcus aureus protein and broad-spectrum adhesin for several host matrix and plasma proteins. We investigated the interactions of full-length Eap and five recombinant tandem repeat domains with host proteins by use of surface plasmon resonance (BIAcore) and ligand overlay assays. In addition, agglutination and host cell interaction, namely, adherence, invasion, and stimulation of proliferation, were determined. With plasmon resonance, the interaction of full-length Eap isoforms (from strains Newman and Wood 46) with fibrinogen, fibronectin, vitronectin, and thrombospondin-1 was found to be specific but with different affinities for the ligands tested. In the ligand overlay assay, the interactions of five single tandem repeat domains (D1 to D5) of Eap-7 (from strain CI-7) with fibronectin, fibrinogen, vitronectin, thrombospondin-1, and collagen I differed substantially. Most prominently, D3 bound most strongly to fibronectin and fibrinogen. Full-length Eap, but none of the single tandem repeat domains, agglutinated S. aureus and enhanced adherence to and invasion of host cells by S. aureus. Constructs D3-4 and D1-3 (in cis) increased adherence and invasiveness compared to what was seen for single Eap tandem repeat domains. By contrast, single Eap tandem repeat domains and full-length Eap similarly modulated the proliferation of peripheral blood mononuclear cells (PBMCs): low concentrations stimulated, whereas high concentrations inhibited, proliferation. Taken together, the data indicate that Eap tandem repeat domains appear to have distinct characteristics for the binding of soluble ligands, despite a high degree of sequence similarity. In addition, more than one Eap tandem repeat domain is required for S. aureus agglutination, adherence, and cellular invasion but not for the stimulation of PBMC proliferation.

Mannan‐Binding Lectin, L‐Ficolin and H‐Ficolin Selectively Binds to Different Bacteria

Mannan‐binding lectin (MBL), L‐ficolin and H‐ficolin are pattern recognition molecules of the innate immune system. We investigated the ability of these molecules to bind to different serotypes and noncapsulated variants of Streptococcus pneumonia and Staphylococcus aureus. We found that MBL binds to noncapsulated S. aureus strain (Wood) but not any of the examined S. pneumoniae serotypes. L‐ficolin binds to some capsulated S. pneumoniae serotypes (11A, 11D and 11F) as well as some capsulated S. aureus serotypes (Type‐1, ‐8, ‐9, ‐11 and ‐12). H‐ficolin does not bind to any of the examined S. pneumoniae and S. aureus serotypes included in this study but did bind to a strain of Aerococcus viridans. When bound to bacteria, MBL and H‐ficolin initiated activation of complement factor C4, whereas L‐ficolin did not. During this study, quantitative assays for the three proteins were developed and the concentration in 97 plasma samples were determined and the median values were estimated at 0.8 μg of MBL/ml, 3.3 μg of L‐ficolin/ml and 18.4 μg of H‐ficolin/ml, respectively.

The Relationship between Longitudinal Growth Strain, Tree Form and Tension Wood at the Stem Periphery of Ten- to Eleven-Year-Old Eucalyptus globulus Labill.

Summary The potential for growth strain measurements for detection of tension wood was assessed in trees from two plantations of 10- to 11-year-old Eucalyptus globulus. Tension wood had commonly developed at or near the stem periphery of straight, vertical and dominant trees. At a localized level growth strain was found to be a good indicator of tension wood. However, in some cases moderate to low growth strain was also detected in some trees where tension wood had been overgrown with small amounts of normal wood. On a whole tree basis the relationship was not as clear. In this case growth strain values determined from multiple measurements appear to be influenced primarily by tissue close to the site of measurements and not by wood at relatively remote locations. In some cases low growth strain values were found in trees with significant tension wood and in others high growth strain values where little tension wood had developed.

Bacterial infections and atopic dermatitis.

Bacterial infections and atopic dermatitis.

Variation of the agr locus in Staphylococcus aureus isolates from cows with mastitis

Staphylococcus aureus isolates from mastitic cow’s milk were examined for production of α-hemolysin and protein A and their accessory gene regulator ( agr locus) was analyzed. An inverse relationship between α-hemolysin and protein A production was found in most of the 76 isolates, suggesting that the isolates tested may be classified into group I (high α-hemolysin/low protein A), II (low α-hemolysin/high protein A), or III (low α-hemolysin/low protein A). The agr locus, which consists of hld, agrB, agrD, agrC, and agrA, was detected in most of the 78 isolates including two reference strains (Wood 46 and Cowan I) by polymerase chain reaction (PCR). When the PCR products for agr locus of 22 isolates from groups I and II were digested with restriction enzyme MboI, seven bands of the expected lengths were recognized in strain Wood 46, but not in the other isolates tested. Nucleotide sequence analysis of PCR products from six isolates revealed that the agr locus sequence of strain Wood 46 corresponded to that of the published sequence data, but the other five isolates from groups I and II diverged at agrB and agrD sequences and thus the deduced amino acid sequences. These variations of agr locus in S. aureus bovine isolates differed from those reported by Ji et al. [Science 276 (1997) 2027].

Evaluation of Standard Surgical Preparation Performed on Superficial Dermal Abrasions

To determine the difference, if any, between the reduction of bacteria on contaminated normal skin and contaminated superficially abraded skin following standard surgical preparations at clinically relevant time points after injury. Prospective animal study. Laboratory. Thirty-two New Zealand white rabbits. Two sites, two by two centimeters, one abraded and one nonabraded (control), were studied on each rabbit. Both were inoculated with encapsulated Staphylococcus aureus strain Wood 46. Four six-millimeter punch biopsies were obtained after inoculation, immediately before surgical scrub, and five minutes and then two hours after completion of the surgical scrub. The rabbits were divided into four cohort groups with surgical scrubs performed at six, twelve, twenty-four, and forty-eight hours after inoculation. Bacterial counts were determined. Numbers of bacteria on surgical sites. Before surgical preparation, the amount of bacteria on the normal skin (control sites) dropped significantly (p<0.02) except in the six-hour group (p<0.20). At the abraded skin sites, the bacteria flourished. The surgical scrub dropped bacterial counts at both the abraded and nonabraded skin sites significantly (p<0.05) except for the abraded site in the twenty-four-hour group (p<0.08). However in the twelve-, twenty-four-, and forty-eight-hour groups, the bacterial counts (colony-forming units) were still markedly elevated (>1x10(5) at abraded sites) when compared with the nonabraded skin sites (p<0.008) at the respective time intervals. Only at the six-hour interval were the bacterial counts reduced similarly at both the abraded and nonabraded skin sites. In a rabbit model the standard surgical preparation using povidone-iodine at six hours after inoculation is effective in reducing the bacterial count on abraded skin to that of surgically prepared nonabraded skin. Beyond that time, the standard surgical preparation is ineffective in reducing counts to those of nonabraded skin at similar time intervals.

Analysis of expression of the alpha-toxin gene (hla) of Staphylococcus aureus by using a chromosomally encoded hla::lacZ gene fusion.

The staphylococcal alpha-toxin (Hla) is a major virulence factor contributing to Staphylococcus aureus pathogenesis. To elucidate the conditions influencing hla expression, the determinant was fused to lacZ, the reporter gene coding for beta-galactosidase. The hla::lacZ fusion was integrated into the chromosome of the wild-type S. aureus strain Wood 46, leading to the variant Wood 46-3. Alpha-toxin expression was found to be dependent on temperature, showing a maximum at 42 degrees C. Furthermore, the indicator strain showed a growth phase-dependent hla regulation which was influenced by temperature. At 37 degrees C, induction of hla::lacZ expression occurred in the late exponential phase of growth, whereas at 42 degrees C, a strong induction was observed as early as the mid-exponential phase. These observations were verified by Northern blot analysis of hla mRNA and by Western blot (immunoblot) analysis of culture supernatants of strain Wood 46. It was additionally found that the induction of hla transcription at 42 degrees C was not coupled with higher concentrations of agr RNAIII, the effector molecule of the global regulator agr. Furthermore, expression of the alpha-toxin was repressed at a high osmolarity. It was also shown that oxygen is essential for hla expression and that cultivation of the S. aureus strain Wood 46-3 on solid medium and in the presence of carbon dioxide stimulated hla transcriptional activity.

Detection of antibodies to Staphylococcus aureus in water buffalo milk by flow cytometry

An assay has been developed to detect antibodies to Staphylococcus aureus in water buffalo milk by flow cytometry. The method was the protein A-deficient strain Wood 46 of S aureus incubated with milk samples and fluorescein-labelled rabbit anti-water buffalo antiserum. The assay can detect antibodies when the pathogen is not detectable by bacterial tests and can determine the antibody titre directly on undiluted samples.

Distribution of capsular materials on the cell wall surface of strain Smith diffuse of Staphylococcus aureus

The fine structure of the capsule of Staphylococcus aureus Smith diffuse was examined by the technique of freeze-substitution and immunoelectron microscopy. The cell surface was covered with a thick layer consisting of fine fibrous structures which were absent from an unencapsulated strain, Smith compact. Anti-teichoic acid antibody did not react with this surface layer but reacted with the surface of strain Smith compact. Anti-capsular antibody, made from the serum of a rabbit immunized with strain Smith diffuse and specific absorption with unencapsulated strain Wood 46, reacted with the fibrous layer of the Smith diffuse strain. Since the anti-teichoic acid antibody did not react with the encapsulated strain Smith diffuse, the capsular layer acts as a barrier to penetration of the anti-teichoic acid antibody through the capsular layer. A portion of a few cell surfaces of the encapsulated strain remained accessible to the anti-teichoic acid antibody. The capsular layer in this portion of the cell surface was thin, and this surface seemed to be a new cell wall surface created by the cell separation.