Antileishmanial Activity of 4,8-Dimethoxynaphthalenyl Chalcones on Leishmania amazonensis.

Leishmaniasis is a neglected tropical disease caused by Leishmania species. Available therapeutic options have several limitations. The drive to develop new, more potent, and selective antileishmanial agents is thus a major goal. Herein we report the synthesis and the biological activity evaluation against promastigote and amastigote forms of Leishmania amazonensis of nine 4,8-dimethoxynaphthalenyl chalcones. Compound ((E)-1-(4,8-dimethoxynaphthalen-1-yl)-3-(4-nitrophenyl)prop-2-en-1-one), 4f, was the most promising with an IC50 = 3.3 ± 0.34 µM (promastigotes), a low cytotoxicity profile (CC50 = 372.9 ± 0.04 µM), and a high selectivity index (SI = 112.6). Furthermore, 4f induced several morphological and ultrastructural changes in the free promastigote forms, loss of plasma membrane integrity, and increased reactive oxygen species (ROS). An in silico analysis of drug-likeness and ADME parameters suggested high oral bioavailability and intestinal absorption. Compound 4f reduced the number of infected macrophages and the number of amastigotes per macrophage, with an IC50 value of 18.5 ± 1.19 µM. Molecular docking studies with targets, ARG and TR, showed that compound 4f had more hydrogen bond interactions with the ARG enzyme, indicating a more stable protein-ligand binding. These results suggest that 4,8-dimethoxynaphthalenyl chalcones are worthy of further study as potential antileishmanial drugs.

Novel Organic Salts Based on Mefloquine: Synthesis, Solubility, Permeability, and In Vitro Activity against Mycobacterium tuberculosis.

The development of novel pharmaceutical tools to efficiently tackle tuberculosis is the order of the day due to the rapid development of resistant strains of Mycobacterium tuberculosis. Herein, we report novel potential formulations of a repurposed drug, the antimalarial mefloquine (MFL), which was combined with organic anions as chemical adjuvants. Eight mefloquine organic salts were obtained by ion metathesis reaction between mefloquine hydrochloride ([MFLH][Cl]) and several organic acid sodium salts in high yields. One of the salts, mefloquine mesylate ([MFLH][MsO]), presented increased water solubility in comparison with [MFLH][Cl]. Moreover, all salts with the exception of mefloquine docusate ([MFLH][AOT]) showed improved permeability and diffusion through synthetic membranes. Finally, in vitro activity studies against Mycobacterium tuberculosis revealed that these ionic formulations exhibited up to 1.5-times lower MIC values when compared with [MFLH][Cl], particularly mefloquine camphorsulfonates ([MFLH][(1R)-CSA], [MFLH][(1S)-CSA]) and mefloquine HEPES ([MFLH][HEPES]).

COVID-19 vaccination and breakthrough infections in patients with cancer.

BACKGROUND: Vaccination is an important preventive health measure to protect against symptomatic and severe COVID-19. Impaired immunity secondary to an underlying malignancy or recent receipt of antineoplastic systemic therapies can result in less robust antibody titers following vaccination and possible risk of breakthrough infection. As clinical trials evaluating COVID-19 vaccines largely excluded patients with a history of cancer and those on active immunosuppression (including chemotherapy), limited evidence is available to inform the clinical efficacy of COVID-19 vaccination across the spectrum of patients with cancer. PATIENTS AND METHODS: We describe the clinical features of patients with cancer who developed symptomatic COVID-19 following vaccination and compare weighted outcomes with those of contemporary unvaccinated patients, after adjustment for confounders, using data from the multi-institutional COVID-19 and Cancer Consortium (CCC19). RESULTS: Patients with cancer who develop COVID-19 following vaccination have substantial comorbidities and can present with severe and even lethal infection. Patients harboring hematologic malignancies are over-represented among vaccinated patients with cancer who develop symptomatic COVID-19. CONCLUSIONS: Vaccination against COVID-19 remains an essential strategy in protecting vulnerable populations, including patients with cancer. Patients with cancer who develop breakthrough infection despite full vaccination, however, remain at risk of severe outcomes. A multilayered public health mitigation approach that includes vaccination of close contacts, boosters, social distancing, and mask-wearing should be continued for the foreseeable future.

The potential for refining nitrogen fertiliser management through accounting for climate impacts: An exploratory study for the Tully region.

Increasing the precision of nitrogen (N) fertiliser management in cropping systems is integral to increasing the environmental and economic sustainability of cropping. In a simulation study, we found that natural variability in year-to-year climate had a major effect on optimum N fertiliser rates for sugarcane in the Tully region of north-eastern Australia, where N discharges pose high risks to Great Barrier Reef ecosystems. There were interactions between climate and other factors affecting crop growth that made optimum N rates field-specific. The regional average optimum N fertiliser rate was substantially lower than current industry guidelines. Likewise, simulated N losses to the environment at optimum N fertiliser rates were substantially lower than the simulated losses at current industry fertiliser guidelines. Dissolved N discharged from rivers is related to fertiliser applications. If the reductions in N applications identified in the study occurred in the Tully region, the reduction in dissolved N discharges from rivers in the region would almost meet current water quality improvement targets. Whilst there were many assumptions made in this exploratory study, and there are many steps between the study and a practically implemented dynamic N fertiliser recommendation system, the potential environmental benefits justify field validation and further development of the concepts identified in the study.

Effects of autoclaving on compressive strength of bovine bones and their use as chewing agents for dogs.

This study aimed to evaluate the effect of autoclave processing on compressive stress of spongy and cortical bones, and the effect of autoclaved bones as chewing agents to reduce dental calculus in adult dogs. Spongy and cortical bones were autoclaved (1 ATM, 30 min, and 120°C) and compressive strength was evaluated in autoclaved and raw bone specimens. Autoclaved bones were offered to ten Beagle dogs divided into two groups of 5 dogs each: Group 1 - received a portion of the autoclaved bovine cortical bone (ACB) and Group 2 - received a portion of the autoclaved bovine spongy bone (ASB). Prior to the experimental period (1-d) and every two days thereafter, oral photographs were taken on both sides of the dental arch to evaluate dental calculus reduction over time. The vestibular surface of the canines, premolars, and molars teeth was evaluated using integration software to measure the proportion between the area covered by calculus and the total teeth area. The effect of bone type, treatment (raw vs. autoclaved), and their interaction were evaluated using the PROC GLIMMIX procedure of SAS (version 9.4). Linear equations were generated to estimate calculus reduction over time for ACB and ASB. Compressive strength was higher (P < 0.05) in cortical bones compared to spongy bones. However, the autoclaving procedure did not affect (P > 0.05) compressive strength, regardless of the bone type. The teeth area covered by calculus of dogs that were offered ACB reduced from 41% to 32% in 5 days, and at the end of 15 days a reduction of 62.2% was observed, resulting in a remaining of 15.5% of teeth area covered by calculus. In this group, the dental calculus area reduced by 57.7% after 5 days, and at the end of the trial, only 5.4% of teeth were still covered by calculus, which represents a reduction of 81%. The linear regression analysis revealed no significant difference between the slopes for the ACB and ASB equations (P > 0.05). No health complications such as tooth fracture, intestinal obstructions, and oral lesions were observed throughout the study. Our results demonstrated that the autoclave processing did not impair compressive strength of spongy and cortical bones. This corroborates with the results observed in vivo, which suggests that autoclaved bones are chewing agents for adult dogs with additional benefits of lower risk of bacterial contamination.

Mefloquine synergism with anti-tuberculosis drugs and correlation to membrane effects: Biologic, spectroscopic and molecular dynamics simulations studies.

Studies displaying the combination of mefloquine (MFL) with anti-tuberculosis (TB) substances are limited in the literature. In this work, the effect of MFL-association with two first-line anti-TB drugs and six fluoroquinolones was evaluated against Mycobacterium tuberculosis drug resistant strains. MFL showed synergistic interaction with isoniazid, pyrazinamide, and several fluoroquinolones, reaching fractional inhibitory concentration indexes (FICIs) ranging from 0.03 to 0.5. In order to better understand the observed results, two approaches have been explored: (i) spectroscopic responses attributed to the effect of MFL on physicochemical properties related to a liposomal membrane model composed by soybean asolectin; (ii) molecular dynamics (MD) simulation data regarding MFL interaction with a membrane model based on PIM2, a lipid constituent of the mycobacterial cell wall. FTIR and NMR data showed that MFL affects expressively the region between the phosphate and the first methylene groups of soybean asolectin membranes, disordering these regions. MD simulations results detected high MFL density in the glycolipid interface and showed that the drug increases the membrane lateral diffusion, enhancing its permeability. The obtained results suggest that synergistic activities related to MFL are attributed to its effect of lipid disorder and membrane permeability enhancement.

Enzyme Immobilization in Covalent Organic Frameworks: Strategies and Applications in Biocatalysis.

The development of efficient catalytic systems is a fundamental aspect for the straightforward production of chemicals. During the last years, covalent organic frameworks (COFs) emerged as an exciting class of organic nanoporous materials. Due to their pre-designable structure, they can be prepared with distinct physicochemical characteristics, specific pore sizes, and tunable functional groups. Moreover, associated with their stability in different media, these materials are considered promising supports for enzyme immobilization. Herein, it is highlighted the recent literature of enzyme immobilization in COFs, the main immobilization strategies, and the catalytic applications of these composites.

Comparison between a commercial blend of functional oils and monensin on the performance and microbiota of coccidiosis-challenged broilers.

The aim of the study was to evaluate the effects of a cashew nut shell oil and commercial castor oil blend (CNSL-Castor oil) on the performance and microbiota of broiler chickens with and without coccidiosis challenge. A total of 864 one-day-old male chicks (Cobb) were randomly distributed to receive 6 treatments (8 pens/treatment; 18 chicks/pen) in a 3 × 2 factorial, with 3 additives (control [non-additives], 100 ppm sodium monensin, or 0.15% CNSL-Castor oil blend), and 2 levels of coccidiosis challenge at 14 D of age (unchallenged or inoculated by gavage with 1 mL of solution containing oocysts sporulated with Eimeria tenella, Eimeria acervulina, and Eimeria maxima). No differences in productive performance were observed among treatments in the pre-challenge period and in unchallenged birds (P > 0.05). Seven-days post-challenge, birds receiving monensin performed better than birds in the positive control group (non-additive and challenge) or in the CNSL-Castor oil group (P > 0.05). However, 14 D post-challenge, birds supplemented with CNSL-Castor oil presented higher weight gain and better feed conversion (P > 0.05), without any change in feed intake (P > 0.05). During the accumulated period (1 to 42 D of age), the live weight, weight gain, and feed intake did not differ between the CNSL-Castor oil and monensin groups, both of which presented higher values than the positive control. Lactobacillus spp. and Clostridium perfringens numbers were increased in the challenged birds (P < 0.05). CNSL-Castor oil supplementation reduced Clostridium cluster XIV, C. perfringens, and S. aureus, compared with the monensin and control groups (P > 0.05). In addition, the CNSL-Castor oil group presented the highest number of Lactobacillus spp. copies, followed by the monensin and positive control groups (P > 0.05). Thus, monensin and CNSL-Castor oil effectively minimized the impact of coccidiosis at different times. While monensin acts as an antimicrobial, CNSL-Castor oil modulates the intestinal microbiota with antimicrobial action against gram-positive bacteria, mainly C. perfringens and S. aureus.

Spectroscopic Investigation of the Effect of Microstructure and Energetic Offset on the Nature of Interfacial Charge Transfer States in Polymer: Fullerene Blends.

Despite performance improvements of organic photovoltaics, the mechanism of photoinduced electron-hole separation at organic donor-acceptor interfaces remains poorly understood. Inconclusive experimental and theoretical results have produced contradictory models for electron-hole separation in which the role of interfacial charge-transfer (CT) states is unclear, with one model identifying them as limiting separation and another as readily dissociating. Here, polymer-fullerene blends with contrasting photocurrent properties and enthalpic offsets driving separation were studied. By modifying composition, film structures were varied from consisting of molecularly mixed polymer-fullerene domains to consisting of both molecularly mixed and fullerene domains. Transient absorption spectroscopy revealed that CT state dissociation generating separated electron-hole pairs is only efficient in the high energy offset blend with fullerene domains. In all other blends (with low offset or predominantly molecularly mixed domains), nanosecond geminate electron-hole recombination is observed revealing the importance of spatially localized electron-hole pairs (bound CT states) in the electron-hole dynamics. A two-dimensional lattice exciton model was used to simulate the excited state spectrum of a model system as a function of microstructure and energy offset. The results could reproduce the main features of experimental electroluminescence spectra indicating that electron-hole pairs become less bound and more spatially separated upon increasing energy offset and fullerene domain density. Differences between electroluminescence and photoluminescence spectra could be explained by CT photoluminescence being dominated by more-bound states, reflecting geminate recombination processes, while CT electroluminescence preferentially probes less-bound CT states that escape geminate recombination. These results suggest that apparently contradictory studies on electron-hole separation can be explained by the presence of both bound and unbound CT states in the same film, as a result of a range of interface structures.

Bacterial Periplasmic Oxidoreductases Control the Activity of Oxidized Human Antimicrobial ß-Defensin 1.

The antimicrobial peptide human ß-defensin 1 (hBD1) is continuously produced by epithelial cells in many tissues. Compared to other defensins, hBD1 has only minor antibiotic activity in its native state. After reduction of its disulfide bridges, however, it becomes a potent antimicrobial agent against bacteria, while the oxidized native form (hBD1ox) shows specific activity against Gram-negative bacteria. We show that the killing mechanism of hBD1ox depends on aerobic growth conditions and bacterial enzymes. We analyzed the different activities of hBD1 using mutants of Escherichia coli lacking one or more specific proteins of their outer membrane, cytosol, or redox systems. We discovered that DsbA and DsbB are essential for the antimicrobial activity of hBD1ox but not for that of reduced hBD1 (hBD1red). Furthermore, our results strongly suggest that hBD1ox uses outer membrane protein FepA to penetrate the bacterial periplasm space. In contrast, other bacterial proteins in the outer membrane and cytosol did not modify the antimicrobial activity. Using immunogold labeling, we identified the localization of hBD1ox in the periplasmic space and partly in the outer membrane of E. coli However, in resistant mutants lacking DsbA and DsbB, hBD1ox was detected mainly in the bacterial cytosol. In summary, we discovered that hBD1ox could use FepA to enter the periplasmic space, where its activity depends on presence of DsbA and DsbB. HBD1ox concentrates in the periplasm in Gram-negative bacteria, which finally leads to bleb formation and death of the bacteria. Thus, the bacterial redox system plays an essential role in mechanisms of resistance against host-derived peptides such as hBD1.

Public Health Implications of Changing Rodent Importation Patterns - United States, 1999-2013.

The United States imports a large volume of live wild and domestic animal species; these animals pose a demonstrated risk for introduction of zoonotic diseases. Rodents are imported for multiple purposes, including scientific research, zoo exhibits and the pet trade. Current U.S. public health regulatory restrictions specific to rodent importation pertain only to those of African origin. To understand the impacts of these regulations and the potential public health risks of international rodent trade to the United States, we evaluated live rodent import records during 1999-2013 by shipment volume and geographic origin, source (e.g. wild-caught versus captive- or commercially bred), intended purpose and rodent taxonomy. Live rodent imports increased from 2737 animals during 1999 to 173 761 animals during 2013. Increases in both the number and size of shipments contributed to this trend. The proportion of wild-captured imports declined from 75% during 1999 to <1% during 2013. Nearly all shipments during these years were imported for commercial purposes. Imports from Europe and other countries in North America experienced notable increases in volume. Gerbils and hamsters arriving from Europe and chinchillas, guinea pigs and hamsters arriving from other countries in North America were predominant taxa underlying this trend. After 2003, African-origin imports became sporadic events under the federal permit process. These patterns suggest development of large-scale captive rodent breeding markets abroad for commercial sale in the United States. While the shift from wild-captured imports alleviates many conservation concerns and risks for novel disease emergence, such consolidated sourcing might elevate exposure risks for zoonotic diseases associated with high-density rodent breeding (e.g. lymphocytic choriomeningitis or salmonellosis). A responsive border health system must periodically re-evaluate importation regulations in conjunction with key stakeholders to ensure a balance between the economic benefits of rodent trade against the potential public health risks.

Paneth cell α-defensin 6 (HD-6) is an antimicrobial peptide.

Defensins protect human barriers from commensal and pathogenic microorganisms. Human α-defensin 6 (HD-6) is produced exclusively by small intestinal Paneth cells but, in contrast to other antimicrobial peptides (AMPs) for HD-6, no direct antibacterial killing activity has been detected so far. Herein, we systematically tested how environmental factors, like pH and reducing conditions, affect antimicrobial activity of different defensins against anaerobic bacteria of the human intestinal microbiota. Remarkably, by mimicking the intestinal milieu we detected for the first time antibacterial activity of HD-6. Activity was observed against anaerobic gut commensals but not against some pathogenic strains. Antibiotic activity was attributable to the reduced peptide and independent of free cysteines or a conserved histidine residue. Furthermore, the oxidoreductase thioredoxin, which is also expressed in Paneth cells, is able to reduce a truncated physiological variant of HD-6. Ultrastructural analyses revealed that reduced HD-6 causes disintegration of cytoplasmic structures and alterations in the bacterial cell envelope, while maintaining extracellular net-like structures. We conclude that HD-6 is an antimicrobial peptide. Our data suggest two distinct antimicrobial mechanisms by one peptide: HD-6 kills specific microbes depending on the local environmental conditions, whereas known microbial trapping by extracellular net structures is independent of the reducing milieu.

Oncolytic adenoviruses: A thorny path to glioma cure.

Glioblastoma Multiforme (GBM) is a rapidly progressing brain tumor. Despite the relatively low percentage of cancer patients with glioma diagnoses, recent statistics indicate that the number of glioma patients may have increased over the past decade. Current therapeutic options for glioma patients include tumor resection, chemotherapy, and concomitant radiation therapy with an average survival of approximately 16 months. The rapid progression of gliomas has spurred the development of novel treatment options, such as cancer gene therapy and oncolytic virotherapy. Preclinical testing of oncolytic adenoviruses using glioma models revealed both positive and negative sides of the virotherapy approach. Here we present a detailed overview of the glioma virotherapy field and discuss auxiliary therapeutic strategies with the potential for augmenting clinical efficacy of GBM virotherapy treatment.

Clinical and diagnostic developments of a gamma interferon release assay for use in bovine tuberculosis control programs.

Currently, the Bovigam assay is used as an official supplemental test within bovine tuberculosis control programs. The objectives of the present study were to evaluate two Mycobacterium bovis-specific peptide cocktails and purified protein derivatives (PPDs) from two sources, liquid and lyophilized antigen preparations. PPDs and peptide cocktails were also used for comparison of a second-generation gamma interferon (IFN-γ) release assay kit with the currently licensed first-generation kit (Bovigam; Prionics AG). Three strains of M. bovis were used for experimental challenge: M. bovis 95-1315, M. bovis Ravenel, and M. bovis 10-7428. Additionally, samples from a tuberculosis-affected herd (i.e., naturally infected) were evaluated. Robust responses to both peptide cocktails, HP (PC-HP) and ESAT-6/CFP10 (PC-EC), and the PPDs were elicited as early as 3 weeks after challenge. Only minor differences in responses to Commonwealth Serum Laboratories (CSL) and Lelystad PPDs were detected with samples from experimentally infected animals. For instance, responses to Lelystad M. avium-derived PPD (PPDa) exceeded the respective responses to the CSL PPDa in M. bovis Ravenel-infected and control animals. However, a 1:4 dilution of stimulated plasma demonstrated greater separation of PPDb from PPDa responses (i.e., PPDb minus PPDa) with the use of Lelystad PPDs, suggesting that Lelystad PPDs provide greater diagnostic sensitivity than CSL PPDs. The responses to lyophilized and liquid antigen preparations did not differ. Responses detected with first- and second-generation IFN-γ release assay kits (Bovigam) did not differ throughout the study. In conclusion, antigens may be stored in a lyophilized state without loss in potency, PC-HP and PC-EC are dependable biomarkers for aiding in the detection of bovine tuberculosis, and second-generation Bovigam kits are comparable to currently used kits.

Cell-mediated reduction of human ß-defensin 1: a major role for mucosal thioredoxin.

Human ß-defensin 1 (hBD-1) is an antimicrobial peptide expressed by epithelia and hematopoietic cells. We demonstrated recently that hBD-1 shows activity against enteric commensals and Candida species only after its disulfide bonds have been reduced by thioredoxin (TRX) or a reducing environment. Here we show that besides TRX, glutaredoxin (GRX) is also able to reduce hBD-1, although with far less efficacy. Moreover, living intestinal and lymphoid cells can effectively catalyze reduction of extracellular hBD-1. By chemical inhibition of the TRX system or specific knockdown of TRX, we demonstrate that cell-mediated reduction is largely dependent on TRX. Quantitative PCR in intestinal tissues of healthy controls and inflammatory bowel disease patients revealed altered expression of some, although not all, redox enzymes, especially in ulcerative colitis. Reduced hBD-1 and TRX localize to extracellular colonic mucus, suggesting that secreted or membrane-bound TRX converts hBD-1 to a potent antimicrobial peptide in vivo.

First Report of Tomato Pith Necrosis (Pseudomonas corrugata) on Tomato (Solanum lycopersicum) in Washington.

Tomato pith necrosis was observed on 2.7% of tomatoes grown in rows covered with black polyethylene, various biodegradable plastics, and an experimental spunbond poly(lactic) acid agricultural mulch in high tunnel and open field experimental plots, in western Washington in 2011. Symptoms developed on 3-month-old plants and progressed acropetally until night temperatures dropped to 10°C. Affected plants had chlorotic leaves, produced adventitious roots, and pith tissue was brown and either corrugated or rotted. Similar symptoms were observed again in 2012 on 2.0% of plants, but only in experimental plots with black polyethylene mulch. Diseased stem tissue was homogenized with a mortar and pestle in sterile water and the extract was streaked onto King's medium B (KMB) agar. Colonies were white and smooth initially, and after 5 days had an irregular surface and margin and produced a tan diffuse pigment. One isolate, Pc.Sl.2011, was gram-negative, grew at 37°C on nutrient broth yeast (NBY) agar, did not fluoresce on KMB (3), and was arginine dihydrolase positive. A partial 16S fragment, 1,387 bp, was obtained via PCR with universal 27f and 1492f primers. The resulting sequence exhibited 99% identity to Pseudomonas corrugata Roberts & Scarlett, and has been assigned GenBank Accession KC812729. Pathogenicity of Pc.Sl.2011 was tested in two greenhouse trials with five replications of one tomato plant per treatment. Seeds of 'Celebrity' were surface sterilized by soaking in 70% EtOH for 30 s and then 10% NaOCl for 30 s, then rinsed with sterile water and sown into 14 cm diameter pots filled with non-sterile Sunshine Mix #1 (SunGro Horticulture Distribution Inc., Bellevue, WA). Seedlings were inoculated at the four leaf stage using 5 ml NBY broth cultures of Pc.Sl.2011 grown at 28°C for 12 h with agitation. A sterile needle was used to inject 10 µl of either sterile water or a bacterial suspension of 1.0 × 1010 CFU/ml into the axil of the second true leaf. Inoculum concentration was confirmed by NBY dilution plate counts. The plants were incubated in clear polyethylene bags for 4 days and placed in a greenhouse at 21.1 ± 1.2°C with a 14-h photoperiod. The first and second trials were sampled at 8 and 9 weeks after inoculation, respectively. Plants inoculated with sterile water had green pith tissue. However, 60 and 40% of inoculated plants had brown pith tissue around the inoculation site in the first and second trial, respectively, but wilting and adventitious roots were not observed. Stem tissue from the inoculation site of symptomatic plants was homogenized as above, and the extract streaked onto NBY agar plates. Three isolates recovered from inoculated plants from both trials had the same characteristics as the original isolate, including similar colony morphology, ability to grow on NBY at 37°C, and lack of fluorescence on KMB. To our knowledge, this is the first documented report of tomato pith necrosis in Washington. Pith necrosis has been reported previously in high tunnel tomato production (4), where excess nitrogen fertilization occurs with cool evening temperatures (3), and when plastic mulch is utilized (2). In the cool climate of western Washington, successful tomato production requires the use of agricultural mulches and covers that trap heat. Since P. corrugata has been isolated from soil and the tomato seeds of inoculated plants (1), local growers attempting to manage pith necrosis need to select tomato seed lots carefully and avoid applying excess nitrogen, especially when using plastic mulch. References: (1) V. Catara. Mol. Plant Pathol. 8:233, 2007. (2) E. J. Sikora and W. S. Gazaway. Online. ACES.edu ANR-0797, 2009. (3) C. M. Scarlett and J. T. Fletcher. Ann. Appl. Biol. 88:105, 1978. (4) X. Xu et al. Plant Dis. 97:988, 2013.

[Human beta-defensin 1: from defence to offence]. / Humanes Beta-Defensin 1: Aus der Defensive gelockt.

The human gut is colonised by about one kilogram of commensal bacteria. These microorganisms are a potential threat, thus an efficient defence system is crucial in preventing bacterial translocation and infection. Besides other mechanisms of protection humans produce antimicrobial peptides (AMPs) that are able to kill a broad range of microorganisms. The human beta-defensin 1 (hBD-1) plays a major role because it is produced constitutively by all human epithelia and some immune cells. In contrast to other AMPs, however, the biological function of hBD-1 has remained unclear since the antibiotic activity of hBD-1 in vitro was only marginal. But still, several diseases have been associated with genetic polymorphisms in the hBD-1 encoding gene. Herein we discuss why the biological role of hBD-1 has been overlooked and how hBD-1 can be activated by chemical reduction. We elaborate on the biological significance of this activation and its importance for inflammatory bowel disease.

First Report of Pectobacterium wasabiae Causing Aerial Stem Rot of Potato in Washington State.

Aerial stem rot of potato (Solanum tuberosum), also known as bacterial stem rot, is often caused by the pectolytic bacteria Pectobacterium (Erwinia) carotovorum subsp. carotovorum, P. atrosepticum, or Dickeya spp. (3). A survey was carried out in August 2008 in 'Russet Burbank' potato fields exhibiting aerial stem rot symptoms in the Columbia Basin of Washington State. One bacterial strain isolated during the survey, PwO405, exhibited pectolytic ability on crystal violet pectate (CVP) agar and potato slices and failed to grow at 37°C, but physiological tests did not conclusively distinguish the bacterium as P. atrosepticum (1). The bacterium was positive for ONPG, N-acetylglucosaminyl transferase, gelatin liquefaction, and acid production from D-galactose, lactose, melibiose, raffinose, citrate, and trehalose. The bacterium was negative for indole production and acid production from maltose, α-methyl-D-glucoside, sorbitol, D-arabitol, inositol, inulin, and melezitose. Molecular identification of the bacterium was performed with 16S rRNA, aconitase (acnA), and malate dehydrogenase (mdh) coding sequences as previously described (2,4). Partial sequences of 16S rRNA (1,408 bp) and acnA (412 bp) genes (GenBank Accession Nos. JQ723958 and JQ723959, respectively) exhibited 99% shared identities with P. wasabiae strain WPP163, while the mdh sequence (435 bp) (GenBank Accession No. JQ723960) exhibited 100% shared identity with mdh sequences from three P. wasabiae strains (NZEC9, NZEC10, and NZEC8974). Maximum parsimony analysis using concatenated acnA and mdh sequences from this study and Pectobacterium sequences previously deposited in GenBank (2,4) clustered strain PwO405 with other P. wasabiae strains. Three 7-week-old 'Russet Norkotah' potato plants were wound-inoculated by inserting a sterile 23 gauge needle just above a central leaf axil at a depth of 1 mm. A 10-µl drop of inoculum (104 CFU) was placed on the wound. Plants were exposed to a 24-h leaf wetness period (90 to 100% RH in a mist chamber) and lesions were measured. All three inoculated plants exhibited aerial stem rot symptoms similar to those observed in the field, including brown water-soaked lesions that spread acropetally and basipetally. Upon drying, the lesions became shriveled and turned dark brown to black. Some plants exhibited hollowing of the stems and unilateral wilt on the side of the lesion. Symptoms were not observed on water-inoculated controls. The bacteria that were reisolated into pure culture from all three inoculated stems caused pitting on CVP and exhibited the same morphology as the original culture and were confirmed as P. wasabiae using 16S rRNA, acnA, and mdh coding sequences, fulfilling Koch's postulates. Stem rot ability of the bacterium was also confirmed on four potato cultivars: 'Ranger Russet,' 'Russet Burbank,' 'Russet Norkotah,' and 'Umatilla Russet' by wound-inoculating six single-stem plants of each cultivar as described above. To our knowledge, this is the first report of aerial stem rot of potato caused by P. wasabiae in Washington State. References: (1) S. De Boer and A. Kelman. Page 56 in: Laboratory Guide for Identification of Plant Pathogenic Bacteria, 3rd ed. N. Schaad et al., ed. APS Press, St. Paul, 2001. (2) A. Pitman et al. Eur. J. Plant Pathol. 32:211, 2010. (3) M. Powelson and G. Franc. Page 10 in: Compendium of Potato Diseases. W. Stevenson et al., ed. APS Press, St. Paul, 2002. (4) M. Yap et al. Appl. Environ. Microbiol. 70:3013, 2004.