Novel cassette array in a class 1 integron in clinical isolates of Acinetobacter baumannii from central Iran

Antibiotic resistance in Acinetobacter baumannii is a major problem in the hospital and outbreaks caused by this organism have been reported frequently. The present study aimed at determining the antibiotic susceptibility patterns, the prevalence of different classes of integrons and the characterization of integron class 1 gene cassettes in Iranian A. baumannii isolates. A total of 63 non-duplicate A. baumannii isolates were collected from clinical and environmental specimens in the Vali-Asr hospital in the central province of Iran (March to September, 2011). The antimicrobial susceptibility for 15 antibiotics which are used conventionally was determined by disk diffusion. The presence of different integron classes was investigated by PCR and the size of gene cassettes in class 1 integrons was then determined by PCR as well. Moreover, integron cassette arrays of isolates were delineated by RFLP and sequencing amplicons with different lengths. Of 63 isolates 62 (98.4%) carried a class 1 integron. The prevalence of IntI2 was 15.9% and the length of the amplicons ranged from 500 bp to 3 kb. Sequencing of integrons of class 1 revealed the presence of many resistance genes (aadA, aacA, aacC, dfrA, bla_GES and bla_IMP). We identified a completely new gene cassette which contained aacA7-qacF-aadA5-bla_IMP, this cassette has not been reported previously in A. baumannii.     

Anticandidal activity of cinnamaldehyde,its ligand and Ni(II) complex: Effect of increase in ring and side chain

To increase efficacy of cinnamaldehyde as an antimycotic agent, N, N′- Bis (trans-cinnamadehyde) ethylenediimine [C₂₀H₂₀N₂] and Ni(II) complex of the type [Ni(C₄₀H₄₀N₄)Cl₂] have been synthesized. The ligand [P] and Ni(II) complex have been characterized on the basis of elemental analysis, FTIR, ESI- MS, IR, ¹H NMR, UV–Vis spectroscopic techniques, conductivity and magnetic measurements. MIC of cinnamaldehyde against clinical isolate of Candida albicans and Candida tropicalis was 400 μg/ml and 500 μg/ml, respectively. Synthesized ligand has markedly reduced MIC; 200 μg/ml and 300 μg/ml whereas Ni(II) complex of ligand displayed MIC of 90 μg/ml and 120 μg/ml. Growth and sensitivity of the organisms were effected by ligand & complex at significantly reduced concentration. Plasma membrane ATPase activity and ergosterol content have been investigated as site of action. Result obtained indicates ergosterol biosynthesis pathway as site of action of cinnamaldehyde, synthesized ligand and its Ni(II) complex.     

Evaluation of antibiotic releasing porous polymethylmethacrylate space maintainers in an infected composite tissue defect model

This study evaluated the in vitro and in vivo performance of antibiotic-releasing porous polymethylmethacrylate (PMMA)-based space maintainers comprising a gelatin hydrogel porogen and a poly(dl-lactic-co-glycolic acid) (PLGA) particulate carrier for antibiotic delivery. Colistin was released in vitro from either gelatin or PLGA microparticle loaded PMMA constructs, with gelatin-loaded constructs releasing colistin over approximately 7 days and PLGA microparticle-loaded constructs releasing colistin for up to 8 weeks. Three formulations with either burst release or extended release at different doses were tested in a rabbit mandibular defect inoculated with Acinetobacter baumannii (2 × 10⁷ colony forming units ml^?1). In addition, one material control that released antibiotic but was not inoculated with A. baumannii was tested. A. baumannii was not detectable in any animal after 12 weeks on culture of the defect, saliva, or blood. Defects with high dose extended release implants had greater soft tissue healing compared with defects with burst release implants, with 8 of 10 animals showing healed mucosae compared with 2 of 10 respectively. Extended release of locally delivered colistin via a PLGA microparticle carrier improved soft tissue healing compared with implants with burst release of colistin from a gelatin carrier.     

Diazeniumdiolate-doped poly(lactic-co-glycolic acid)-based nitric oxide releasing films as antibiofilm coatings

Nitric oxide (NO) releasing films with a bilayer configuration are fabricated by doping dibutyhexyldiamine diazeniumdiolate (DBHD/N(2)O(2)) in a poly(lactic-co-glycolic acid) (PLGA) layer and further encapsulating this base layer with a silicone rubber top coating. By incorporating pH sensitive dyes within the films, pH changes in the PLGA layer are visualized and correlated with the NO release profiles (flux vs. time). It is demonstrated that PLGA acts as both a promoter and controller of NO release from the coating by providing protons through its intrinsic acid residues (both end groups and monomeric acid impurities) and hydrolysis products (lactic acid and glycolic acid). Control of the pH changes within the PLGA layer can be achieved by adjusting the ratio of DBHD/N(2)O(2) and utilizing PLGAs with different hydrolysis rates. Coatings with a variety of NO release profiles are prepared with lifetimes of up to 15 d at room temperature (23?°C) and 10 d at 37?°C. When incubated in a CDC flow bioreactor for a one week period at RT or 37?°C, all the NO releasing films exhibit considerable antibiofilm properties against gram-positive Staphylococcus aureus and gram-negative Escherichia coli. In particular, compared to the silicone rubber surface alone, an NO releasing film with a base layer of 30?wt% DBHD/N(2)O(2) mixed with poly(lactic acid) exhibits an ～98.4% reduction in biofilm biomass of S.?aureus and ～99.9% reduction for E.?coli at 37?°C. The new diazeniumdiolate-doped PLGA-based NO releasing coatings are expected to be useful antibiofilm coatings for a variety of indwelling biomedical devices (e.g., catheters).     

Real-time evaluation of nitric oxide (NO) levels in cortical and hippocampal areas with a nanopore-based electrochemical NO sensor

Nitric oxide (NO) is an important biomolecule for regulating various brain functions, such as the control of neurovascular tone. NO, however, cannot be stored inside cells where NO is produced and immediately diffuses through the cellular membrane and decays rapidly, which makes the detection of NO extremely hard in an in vivo setting. We constructed an amperometric NO nanosensor and utilized it to directly measure NO release in the living brain. The NO nanosensor uses nanopores (pores with an opening radii <500 nm) in which NO is oxidized at the porous platinum surface. The nanopore-based sensor was inserted vertically into the brains of anesthetized mice up to the end of the hippocampal CA 3 region, or to a depth of about 3 mm. The sensor was slowly advanced in the brain in 0.5 μm increments and in 0.05 s temporal steps. Different levels of NO release were monitored by the nanopore NO sensor during the course of the penetration. The hippocampal CA3 region had the highest level of NO release, which was followed by CA2 and CA1 of the hippocampus and the cortex. The levels of NO release were not uniformly distributed within the cortical and hippocampal areas of living brain. In sum, the nanopore-based NO sensor was able to grossly measure NO contents within living brain in real time and with high sensitivity. This study may provide good insights about the relationship between the distributions of NOS-immunoreactive neurons and the directly measured levels of NO release in brain.     

Role of flavohemoglobin in combating nitrosative stress in uropathogenic Escherichia coli – Implications for urinary tract infection

During the course of urinary tract infection (UTI) nitric oxide (NO) is generated as part of the host response. This study investigates the significance of the NO-detoxifying enzyme flavohemoglobin (Hmp) in protection of uropathogenic Escherichia coli (UPEC) against nitrosative stress. An hmp (J96Δhmp) knockout mutant of UPEC strain J96 was constructed using single-gene deletion. The viability of J96Δhmp was significantly reduced (P < 0.001) compared to the wild-type strain after exposure to the NO-donor DETA/NO. The NO consumption in J96Δhmp was significantly (P < 0.001) impaired compared to J96wt. Screening UPEC isolates from patients with UTI revealed increased hmp expression in all patients. In a competition-based mouse model of UTI, the hmp mutant strain was significantly (P < 0.05) out-competed by the wild-type strain. This study demonstrates, for the first time, that Hmp contributes to the protection of UPEC against NO-mediated toxicity in vitro. In addition, hmp gene expression occurs in UPEC isolates from the infected human urinary tract and UPEC that were hmp-deficient had a reduced ability to colonize the mouse urinary tract. Taken together the results suggest that NO detoxification by Hmp may be a fitness advantage factor in UPEC, and a potentially interesting target for development of novel treatment concepts for UTI.     

Antibacterial and cell-adhesive polypeptide and poly(ethylene glycol) hydrogel as a potential scaffold for wound healing

The ideal wound-healing scaffold should provide the appropriate physical and mechanical properties to prevent secondary infection, as well as an excellent physiological environment to facilitate cell adhesion, proliferation and/or differentiation. Therefore, we developed a synthetic cell-adhesive polypeptide hydrogel with inherent antibacterial activity. A series of polypeptides, poly(Lys)_x(Ala)_y (x + y = 100), with varied hydrophobicity via metal-free ring-opening polymerization of NCA-Lys(Boc) and NCA-Ala monomers (NCA = N-carboxylic anhydride) mediated by hexamethyldisilazane (HMDS) were synthesized. These polypeptides were cross-linked with 6-arm polyethylene glycol (PEG)-amide succinimidyl glutarate (ASG) (M_w = 10 K) to form hydrogels with a gelation time of five minutes and a storage modulus (G′) of 1400-3000 Pa as characterized by rheometry. The hydrogel formed by cross-linking of poly(Lys)₆₀(Ala)₄₀ (5 wt.%) and 6-arm PEG-ASG (16 wt.%) (Gel-III) exhibited cell adhesion and cell proliferation activities superior to other polypeptide hydrogels. In addition, Gel-III displays significant antibacterial activity against Escherichia coli JM109 and Staphylococcus aureus ATCC25923. Thus, we have developed a novel, cell-adhesive hydrogel with inherent antibacterial activity as a potential scaffold for cutaneous wound healing.     

The mediation of platelet quiescence by NO-releasing polymers via cGMP-induced serine 239 phosphorylation of vasodilator-stimulated phosphoprotein

Nitric oxide (NO) releasing (NORel) materials have been shown to create localized increases in NO concentration by the release of NO from a diazeniumdiolate-containing or S-nitrosothiol-containing polymer coating and the improvement of extracorporeal circulation (ECC) hemocompatibility. However, the mechanism and, in particular, the platelet upregulation of the NO/cGMP signaling protein, vasodilator-stimulated phosphoprotein phosphorylated at serine 239 (P-VASP (ser 239)), for the improved ECC hemocompatibility via NO release still needs elucidation. In this work, two NORel polymeric coatings were evaluated in a 4 h rabbit thrombogenicity model and the anti-thrombotic mechanism investigated for rabbit platelet P-VASP upregulation. Polymer films containing 25 wt% diazeniumdiolated dibutylhexanediamine (DBHD) or 5 wt% S-nitroso-N-acetylpenicillamine (SNAP) coated on the inner walls of ECC circuits yielded significantly reduced ECC thrombus formation and maintained normal platelet aggregation compared to polymer controls after 4 h of blood exposure. Platelet P-VASP (ser 239), a useful tool to monitor NO/cGMP signaling, was upregulated after 4 h on ECC and markedly increased after ex vivo sodium nitroprusside (SNP) stimulation. Interestingly, in the rabbit platelet, NO did not upregulate the cAMP P-VASP phosphoprotein P-VASP (ser 157) as previously shown in human platelets. These results suggest that NORel polymers preserve rabbit platelet quiescence by sustaining a level of cGMP signaling as monitored by P-VASP (ser 239) upregulation. The upregulation of this NO-mediated platelet signaling mechanism in this rabbit thrombogenicity model indicates the potential for improved thromboresistance of any NORel-coated medical device.     

Porous silicon oxide–PLGA composite microspheres for sustained ocular delivery of daunorubicin

A water-soluble anthracycline antibiotic drug (daunorubicin, DNR) was loaded into oxidized porous silicon (pSiO₂) microparticles and then encapsulated with a layer of polymer (poly lactide-co-glycolide, PLGA) to investigate their synergistic effects in control of DNR release. Similarly fabricated PLGA–DNR microspheres without pSiO₂, and pSiO₂ microparticles without PLGA were used as control particles. The composite microparticles synthesized by a solid-in-oil-in-water emulsion method have mean diameters of 52.33 ± 16.37 μm for PLGA–pSiO₂_21/40–DNR and the mean diameter of 49.31 ± 8.87 μm for PLGA–pSiO₂_6/20–DNR. The mean size, 26.00 ± 8 μm, of PLGA–DNR was significantly smaller, compared with the other two (P < 0.0001). Optical microscopy revealed that PLGA–pSiO₂–DNR microspheres contained multiple pSiO₂ particles. In vitro release experiments determined that control PLGA–DNR microspheres completely released DNR within 38 days and control pSiO₂–DNR microparticles (with no PLGA coating) released DNR within 14 days, while the PLGA–pSiO₂–DNR microspheres released DNR for 74 days. Temporal release profiles of DNR from PLGA–pSiO₂ composite particles indicated that both PLGA and pSiO₂ contribute to the sustained release of the payload. The PLGA–pSiO₂ composite displayed a more constant rate of DNR release than the pSiO₂ control formulation, and displayed a significantly slower release of DNR than either the PLGA or pSiO₂ formulations. We conclude that this system may be useful in managing unwanted ocular proliferation when formulated with antiproliferation compounds such as DNR.     

Prévalence de Candida parapsilosis, C. orthopsilosis et de C. metapsilosis au sein des candidémies au CHU de Nantes et profil de sensibilité aux échinocandines par la méthode E-test : étude rétrospective de cinq ans (2004-2009)

Aim of the study

To determine the prevalence of C. parapsilosis sensu stricto, C. orthopsilosis and C. metapsilosis among candidemia at Nantes University Hospital and to evaluate the in vitro susceptibility of the isolates against three echinocandin drugs (caspofungin, micafungin and anidulafungin).

Material and methods

Retrospective study (march 2004 to july 2009) of 178 cases of candidemia corresponding to 183 Candida spp. strains identified by means of routine phenotypical methods. Re-identification of C. parapsilosis sensu lato isolates was performed by ITS rDNA sequencing analysis. Minimal inhibitory concentrations (MIC) were determined by E-test^®. All echinocandin non-susceptible isolates (MIC > 2 μg/mL) were analyzed for the presence/absence of FKS1 mutations associated with resistance.

Results

During this period, C. parapsilosis sensu lato was responsible for 27 candidemia, ranging at the second most common Candida species after C. albicans (n = 99, 54.1%). Neither isolates belong to C. orthopsilosis nor C. metapsilosis. According to the literature, all the isolates displayed high MICs against the three echinocandin drugs. All the isolates displayed both susceptibility (MIC ≤ 2 μg/mL) and a good agreement between MICs read at 24 h and 48 h for caspofungin and micafungin (MIC₅₀ = 0.75 μg/mL, MIC₉₀ = 1.5 μg/mL). Surprisingly, whereas most of the strains were susceptible to anidulafungin at 24 h (MIC₅₀ = 1 μg/mL, MIC₉₀ = 1.5 μg/mL), 14 (52 %) displayed non-susceptibility, despite the lack of mutation associated with resistance on FKS1, when reading was performed at 48 h (MIC₅₀ = 3 μg/mL, MIC₉₀ = 12 μg/mL).

Conclusion

Prevalence of C. orthopsilosis and C. metapsilosis in patients with candidemia is low at Nantes University Hospital. The difficulty encountered with MIC reading by E-test^® are discussed.     

Association analysis of GRIN1 and GRIN2B polymorphisms and Parkinson's disease in a hospital-based case–control study

Hyperactivation of N-methyl-d-aspartate receptors (NMDARs) leads to neuronal excitotoxicity and is suggested to play a role in many brain disorders, including Alzheimer's disease and schizophrenia. However, the association between polymorphisms in the genes that code for NMDAR subunits, N-methyl-d-aspartate 1 and 2B (GRIN1 and GRIN2B) and Parkinson's disease (PD) remains unclear. In a hospital-based case–control study of PD, DNA samples were collected from 101 PD patients and 205 healthy controls. Genotyping assays were used to screen for polymorphisms in the GRIN1 (rs2301364 T > C, rs28489906 T > C, and rs4880213 T > C) and GRIN2B (C366G, C2664T, and rs1805476 T > G) genes, and logistic regression analysis was then used to assess the association between these single nucleotide polymorphisms (SNPs) and PD susceptibility. None of the 6 SNPs were significantly associated with PD risk on their own. However, in conjunction with putative low-risk genotypes for the GRIN1 gene, the GRIN2BC366G variant was significantly associated with reduced PD risk compared with the homozygous genotype 366CC (OR = 0.38, 95%CI = 0.17–0.93, P = 0.033). A synergistic effect on risk reduction was observed in subjects who carried multiple polymorphisms of GRIN1 and the GRIN2BC366G polymorphism (OR = 0.78, 95%CI = 0.59–1.02, P_trend = 0.073). Our results suggest that polymorphisms in the GRIN1 and GRIN2B genes may serve as potential biomarkers for a reduced risk of PD among the Chinese population in Taiwan.     

Association of the suppressor of cytokine signaling 1 (SOCS1) gene polymorphisms with acute coronary syndrome in Mexican patients

Recent studies provide evidence on the emerging role of the SOCS1 gene in the development and progression of atherosclerotic lesions. This gene encodes for the suppressor of the cytokine signaling-1 protein that interacts directly with the Janus kinases that are essential intracellular mediators of the immune cytokine action. The aim of this study was to test for associations between SOCS1 gene single nucleotide polymorphisms (SNPs) and the risk of developing acute coronary syndromes (ACS) in a group of Mexicans patients. Four SNPs [-3969 C > T (rs243327), -1656 G > A (rs243330), -820 G > T (rs33977706) and +1125 G > C (rs33932899)] of SOCS1 gene were determined for TaqMan genotyping assays in a group of 447 patients with ACS and 622 healthy controls. Under heterozygous model, the -3969 C > T (rs243327) SNP was associated with increased risk of ACS (OR = 1.45, P_Het = 0.021). On the other hand, under co-dominant and heterozygous models, the -1656 G/A (rs243330) SNP was associated with increased risk of ACS (OR = 1.47, P_Co-dom = 0.038 and OR = 1.50, P_Het = 0.013, respectively). Moreover, under co-dominant, dominant, and heterozygous models, the -820 T/G (rs33977706) SNP was associated with increased risk of ACS (OR = 1.59, P_Co-dom = 0.03, OR = 1.48, P_Dom = 0.028 and OR = 1.61, P_Het = 0.01). Finally, under co-dominant and heterozygous models, the +1125 G/C (rs33932899) SNP was associated with increased risk of ACS (OR = 1.54, P_Co-dom = 0.006, OR = 1.58, P_Het = 0.012, respectively). Models were adjusted for gender, age, body index mass, dyslipidemia, alcohol consumption, and smoking. In summary, our data suggests that the four studied polymorphisms of the SOCS1 gene play an important role as susceptibility markers for developing ACS.     

Leptin induces nitric oxide synthase type II in C6 glioma cells: Role for nuclear factor-κB in hormone effect

Astrocytes in the CNS produce inflammatory mediators in response to several stimuli and cytokines. Here we investigated the in vitro effect of leptin on inducible nitric oxide synthase (iNOS) expression in a glioma cell line (C6). After hormone stimulation, culture media were analysed for accumulated stable oxidation products of NO (NO₂⁻ and NO₃⁻, designated as NO_x), cellular RNA was extracted to determine iNOS mRNA level by RT-PCR and cellular lysates were prepared for protein expression. Leptin induced a concentration-dependent increase of NO release, related to iNOS induction. This effect was potentiated by IFN-γ, or TNF-α, or IFN-γ plus IL-1β. Pyrrolidine dithiocarbammate (PDTC) and N-α-tosyl-l-lysine chloromethyl ketone (TLCK), two inhibitors of NF-κB activation, as well as the specific proteasome inhibitor MG132, blocked leptin-induced iNOS. The role of NF-κB was also confirmed by time course studies on degradation of IκB-α, which began to degrade 5 min after treatment with leptin and returned to basal level after 30–60 min. Pre-incubation of cells with MG132 inhibited leptin-induced IκB-α degradation. These results confirm the pro-inflammatory role of leptin and identify it as a potential up-regulator of cytokine-induced inflammatory response in the CNS.     

Altered Ca homeostasis in the skeletal muscle of DJ − 1 null mice

Loss-of-function mutations in DJ − 1 are associated with early-onset of Parkinson's disease. Although DJ − 1 is ubiquitously expressed, the functional pathways affected by it remain unresolved. Here we demonstrate an involvement of DJ − 1 in the regulation of Ca²⁺ homeostasis in mouse skeletal muscle. Using enzymatically dissociated flexor digitorum brevis muscle fibers from wild-type (wt) and DJ − 1 null mice, we examined the effects of DJ − 1 protein on resting, cytoplasmic [Ca²⁺] ([Ca²⁺]_i) and depolarization-evoked Ca²⁺ release in the mouse skeletal muscle. The loss of DJ − 1 resulted in a more than two-fold increase in resting [Ca²⁺]_i. While there was no alteration in the resting membrane potential, there was a significant decrease in depolarization-evoked Ca²⁺ release from the sarcoplasmic reticulum in the DJ − 1 null muscle cells. Consistent with the role of DJ − 1 in oxidative stress regulation and mitochondrial functional maintenance, treatments of DJ − 1 null muscle cells with resveratrol, a mitochondrial activator, or glutathione, a potent antioxidant, reversed the effects of the loss of DJ − 1 on Ca²⁺ homeostasis. These results provide evidence of DJ − 1's association with Ca²⁺ regulatory pathways in mouse skeletal muscle, and suggest the potential benefit of resveratrol to functionally compensate for the loss of DJ − 1.     

Yersinia enterocolitica and Photorhabdus asymbiotica β-lactamases BlaA are exported by the twin-arginine translocation pathway

In general, β-lactamases of medically important Gram-negative bacteria are Sec-dependently translocated into the periplasm. In contrast, β-lactamases of Mycobacteria spp. (BlaC, BlaS) and the Gram-negative environmental bacteria Stenotrophomonas maltophilia (L2) and Xanthomonas campestris (Bla_XCC-1) have been reported to be secreted by the twin-arginine translocation (Tat) system. Yersinia enterocolitica carries 2 distinct β-lactamase genes (blaA and blaB) encoding BlaA_Ye and the AmpC-like β-lactamase BlaB, respectively. By using the software PRED-TAT for prediction and discrimination of Sec from Tat signal peptides, we identified a functional Tat signal sequence for Yersinia BlaA_Ye. The Tat-dependent translocation of BlaA_Ye could be clearly demonstrated by using a Y. enterocolitica tatC-mutant and cell fractionation. Moreover, we could demonstrate a unique unusual temperature-dependent activity profile of BlaA_Ye ranging from 15 to 60 °C and a high ‘melting temperature’ (T_M = 44.3°) in comparison to the related Sec-dependent β-lactamase TEM-1 (20–50 °C, T_M = 34.9 °C). Strikingly, the blaA gene of Y. enterocolitica is present in diverse environmental Yersinia spp. and a blaA homolog gene could be identified in the closely related Photorhabdus asymbiotica (BlaA_Pa; 69% identity to BlaA_Ye). For BlaA_Pa of P. asymbiotica, we could also demonstrate Tat-dependent secretion. These results suggest that Yersinia BlaA-related β-lactamases may be the prototype of a large Tat-dependent β-lactamase family, which originated from environmental bacteria.     

Face-to-face versus computer-delivered alcohol interventions for college drinkers: A meta-analytic review, 1998 to 2010

Alcohol misuse occurs commonly on college campuses, necessitating prevention programs to help college drinkers reduce consumption and minimize harmful consequences. Computer-delivered interventions (CDIs) have been widely used due to their low cost and ease of dissemination but whether CDIs are efficacious and whether they produce benefits equivalent to face-to-face interventions (FTFIs) remain unclear. Therefore, we identified controlled trials of both CDIs and FTFIs and used meta-analysis (a) to determine the relative efficacy of these two approaches and (b) to test predictors of intervention efficacy. We included studies examining FTFIs (N = 5237; 56% female; 87% White) and CDIs (N = 32,243; 51% female; 81% White). Independent raters coded participant characteristics, design and methodological features, intervention content, and calculated weighted mean effect sizes using fixed and random-effects models. Analyses indicated that, compared to controls, FTFI participants drank less, drank less frequently, and reported fewer problems at short-term follow-up (d₊s = 0.15–0.19); they continued to consume lower quantities at intermediate (d₊ = 0.23) and long-term (d₊ = 0.14) follow-ups. Compared to controls, CDI participants reported lower quantities, frequency, and peak intoxication at short-term follow-up (d₊s = 0.13–0.29), but these effects were not maintained. Direct comparisons between FTFI and CDIs were infrequent, but these trials favored the FTFIs on both quantity and problem measures (d₊s = 0.12–0.20). Moderator analyses identified participant and intervention characteristics that influence intervention efficacy. Overall, we conclude that FTFIs provide the most effective and enduring effects.     

Different Staphylococcus aureus whole bacteria mutated in putative pro-inflammatory membrane components have similar cytokine inducing activity

The role of the different major cell wall components of Gram-positive bacteria for immune stimulation is controversial. We thus compared the cytokine inducing capacity of different Staphylococcus aureus (SA) mutants lacking either lipoproteins (SA 113 Δlgt), or wall teichoic acids (WTA) (ΔTA), or possessing a reduced d-alanine content in lipoteichoic acid (LTA) (SA 113 Δdlt) to its corresponding wildtype (SA 113 wt). Inactivated whole bacteria and their purified cell wall components peptidoglycan and LTA, were used to stimulate human whole blood and macrophages from TLR2 knock-out mice. We found that all S. aureus strains induced similar amounts of TNF, IL-8 and IL-10 and none of them was dependent on the presence of TLR2. Surprisingly, in case of SA 113 Δlgt a significant attenuated release of only IL-1β protein and mRNA in human whole blood was observed. Highly purified peptidoglycan from all strains in contrast to LTA had a very low activity in stimulating cytokine release. Taken together these results demonstrate that major cell wall alterations like lack of WTA, lipoproteins or alterations in d-alanine content do not affect the overall cytokine inducing potential of whole bacteria and thus cytokine induction is initiated by redundant mechanisms.     

NO-loaded Zn2+-exchanged zeolite materials: A potential bifunctional anti-bacterial strategy

Nitric oxide (NO) is important for the regulation of a number of diverse biological processes, including vascular tone, neurotransmission, inflammatory cell responsiveness, defence against invading pathogens and wound healing. Transition metal exchanged zeolites are nanoporous materials with high-capacity storage properties for gases such as NO. The NO stores are liberated upon contact with aqueous environments, thereby making them ideal candidates for use in biological and clinical settings. Here, we demonstrate the NO release capacity and powerful bactericidal properties of a novel NO-storing Zn²⁺-exchanged zeolite material at a 50 wt.% composition in a polytetrafluoroethylene polymer. Further to our published data showing the anti-thrombotic effects of a similar NO-loaded zeolite, this study demonstrates the anti-bacterial properties of NO-releasing zeolites against clinically relevant strains of bacteria, namely Gram-negative Pseudomonas aeruginosa and Gram-positive methicillin-sensitive and methicillin-resistant Staphylococcus aureus and Clostridium difficile. Thus our study highlights the potential of NO-loaded zeolites as biocompatible medical device coatings with anti-infective properties.     

Age-dependent association of mannose-binding lectin polymorphisms with the development of pulmonary tuberculosis in Viet Nam

Mannose-binding lectin (MBL) binds to pathogens and induces complement-mediated opsonophagocytosis. Although the association between MBL2 polymorphisms and tuberculosis (TB) has been studied in various populations, the results are controversial. We explored the stages of TB associated with MBL2 polymorphisms. X/Y (rs7096206) and A/B (rs1800450) were genotyped in 765 new patients with active pulmonary TB without HIV infection and 556 controls in Hanoi, Viet Nam. The MBL2 nucleotide sequences were further analyzed, and plasma MBL levels were measured in 109 apparently healthy healthcare workers and 65 patients with TB. Latent TB infection (LTBI) was detected by interferon-gamma release assay (IGRA). The YA/YA diplotype, which exhibited high plasma MBL levels, was associated with protection against active TB in younger patients (mean age = 32) ≦ 45 years old (odds ratio, 0.61; 95% confidence interval, 0.46–0.80). The resistant diplotype was less frequently found in the younger patients at diagnosis (P = 0.0021). MBL2 diplotype frequencies and plasma MBL levels were not significantly different between the IGRA-positive and -negative groups. MBL2 YA/YA exhibited a protective role against the development of TB in younger patients, whereas the MBL2 genotype and MBL levels were not associated with LTBI. High MBL levels may protect against the early development of pulmonary TB after infection.     

Nrf2-encoding NFE2L2 haplotypes influence disease progression but not risk in Alzheimer's disease and age-related cataract

Alzheimer's disease (AD) and age-related cataract, disorders characterized by protein aggregation causing late-onset disease, both involve oxidative stress. We hypothesize that common variants of NFE2L2 and KEAP1, the genes encoding the main regulators of the Nrf2 system, an important defence system against oxidative stress, may influence risk of AD and/or age-related cataract. This case-control study combines an AD material (725 cases and 845 controls), and a cataract material (489 cases and 182 controls). Genetic variation in NFE2L2 and KEAP1 was tagged by eight and three tag single nucleotide polymorphisms (SNPs), respectively. Single SNPs and haplotypes were analyzed for associations with disease risk, age parameters, MMSE and AD cerebrospinal fluid biomarkers. NFE2L2 and KEAP1 were not associated with risk of AD or cataract. However, one haplotype allele of NFE2L2 was associated with 2 years earlier age at AD onset (p_c = 0.013) and 4 years earlier age at surgery for posterior subcapsular cataract (p_c = 0.019). Another haplotype of NFE2L2 was associated with 4 years later age at surgery for cortical cataract (p_c = 0.009). Our findings do not support NFE2L2 or KEAP1 as susceptibility genes for AD or cataract. However, common variants of the NFE2L2 gene may affect disease progression, potentially altering clinically recognized disease onset.