ResearchPad - toxins https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Functional and structural consequences of epithelial cell invasion by <i>Bordetella pertussis</i> adenylate cyclase toxin]]> https://www.researchpad.co/article/elastic_article_7693 Bordetella pertussis, the causative agent of whopping cough, produces an adenylate cyclase toxin (CyaA) that plays a key role in the host colonization by targeting innate immune cells which express CD11b/CD18, the cellular receptor of CyaA. CyaA is also able to invade non-phagocytic cells, via a unique entry pathway consisting in a direct translocation of its catalytic domain across the cytoplasmic membrane of the cells. Within the cells, CyaA is activated by calmodulin to produce high levels of cyclic adenosine monophosphate (cAMP) and alter cellular physiology. In this study, we explored the effects of CyaA toxin on the cellular and molecular structure remodeling of A549 alveolar epithelial cells. Using classical imaging techniques, biochemical and functional tests, as well as advanced cell mechanics method, we quantify the structural and functional consequences of the massive increase of intracellular cyclic AMP induced by the toxin: cell shape rounding associated to adhesion weakening process, actin structure remodeling for the cortical and dense components, increase in cytoskeleton stiffness, and inhibition of migration and repair. We also show that, at low concentrations (0.5 nM), CyaA could significantly impair the migration and wound healing capacities of the intoxicated alveolar epithelial cells. As such concentrations might be reached locally during B. pertussis infection, our results suggest that the CyaA, beyond its major role in disabling innate immune cells, might also contribute to the local alteration of the epithelial barrier of the respiratory tract, a hallmark of pertussis.

]]>
<![CDATA[Virulence factors and antibiograms of <i>Escherichia coli</i> isolated from diarrheic calves of Egyptian cattle and water buffaloes]]> https://www.researchpad.co/article/elastic_article_8462 Diarrhea caused by Escherichia coli in calves is an important problem in terms of survivability, productivity and treatment costs. In this study, 88 of 150 diarrheic animals tested positive for E. coli. Of these, 54 samples had mixed infection with other bacterial and/or parasitic agents. There are several diarrheagenic E. coli pathotypes including enteropathogenic E. coli (EPEC), Shiga-toxin producing E. coli (STEC), enterotoxigenic E. coli (ETEC) and necrotoxigenic E. coli (NTEC). Molecular detection of virulence factors Stx2, Cdt3, Eae, CNF2, F5, Hly, Stx1, and ST revealed their presence at 39.7, 27.2, 19.3, 15.9, 13.6, 9.0, 3.4, and 3.4 percent, respectively. As many as 13.6% of the isolates lacked virulence genes and none of the isolate had LT or CNF1 toxin gene. The odds of isolating ETEC from male calves was 3.6 times (95% CI: 1.1, 12.4; P value = 0.042) that of female calves, whereas the odds of isolating NTEC from male calves was 72.9% lower (95% CI: 91.3% lower, 15.7% lower; P value = 0.024) than that in females. The odds of isolating STEC in winter was 3.3 times (95% CI: 1.1, 10.3; P value = 0.037) that of spring. Antibiograms showed 48 (54.5%) of the isolates to be multi-drug resistant. The percent resistance to tetracycline, streptomycin, ampicillin, and trimethoprim-sulfamethoxazole was 79.5, 67.0, 54.5, and 43.0, respectively. Ceftazidime (14.8%), amoxicillin-clavulanic acid (13.6%) and aztreonam (11.3%) showed the lowest resistance, and none of the isolates was resistant to imipenem. The results of this study can help improve our understanding of the epidemiological aspects of E. coli infection and to devise strategies for protection against it. The prevalence of E. coli pathotypes can help potential buyers of calves to avoid infected premises. The antibiograms in this study emphasizes the risks associated with the random use of antibiotics.

]]>
<![CDATA[Effects of sea-level rise on physiological ecology of populations of a ground-dwelling ant]]> https://www.researchpad.co/article/N7f89605c-5421-4b76-a019-ba0e7ddd5b34

Introduction

Sea-level rise is a consequence of climate change that can impact the ecological and physiological changes of coastal, ground-dwelling species. Sea-level rise has a potential to inundate birds, rodents, spiders, and insects that live on the ground in coastal areas. Yet, there is still much to be learned concerning the specifics of these impacts. The red imported fire ant Solenopsis invicta (Buren) excavates soil for its home and is capable of surviving flooding. Because of their ground-dwelling life history and rapid reproduction, fire ants make an ideal model for discovery and prediction of changes that may be due to sea-level rise. There are up to 500,000 individuals in a colony, and these invasive ants naturally have a painful sting. However, observations suggest that colonies of fire ants that dwell in tidally-influenced areas are more aggressive with more frequent stings and more venom injected per sting (behavioral and physiological changes) than those located inland. This may be an adaption to sea-level rise. Therefore, the objective of this study is to elucidate differences in inland and coastal defensiveness via micro-dissection and comparison of head width, head length, stinger length, and venom sac volume. But first because fire ants’ ability to raft on brackish tidal water is unknown, it had to be determined if fire ants could indeed raft in brackish water and examine the behavior differences between those flooded with freshwater vs. saltwater.

Methods

To test the coastal-aggression hypothesis, inland colonies and coastal colonies, which experience relatively greater amounts of flooding, specifically regular tidal and windblown water and oscillations (i.e. El Nińo Southern Oscillation) from the Gulf of Mexico, were collected. To mimic sea-level rise, the colonies were flooded in salinities that correspond to both their collection site and conditions found in a variety of locales and situations (such as storm surge from a tropical storm). Individual ants were immediately taken from each colony for dissection before flooding, 1-hour into flooding, and 24-hours into flooding.

Results and discussion

Fire ants use their venom to defend themselves and to communicate alarm or aggression. Dissections and measurement of heads, venom sacs, and stingers revealed both coastal and inland colonies experience an increase in venom sac volume after 24 hours; in fact coastal colonies increased their venom volume by 75% after 24 h of flooding Whether this venom sac enlargement is due to diffusion of water or venom sac production is unknown. These ground-dwelling ants exhibit physiological and behavioral adaptations to ongoing sea-level rise possibly indicating that they are responding to increased flooding. Fire ants will raft on high-salinity water; and sea-level rise may cause stings by flooded ants to be more severe because of increased venom volume.

]]>
<![CDATA[Lateral flow immunoassay (LFIA) for the detection of lethal amatoxins from mushrooms]]> https://www.researchpad.co/article/N089b971a-62b1-4256-a74f-acfba8aef66c

The mushroom poison that causes the most deaths is the class of toxins known as amatoxins. Current methods to sensitively and selectively detect these toxins are limited by the need for expensive equipment, or they lack accuracy due to cross-reactivity with other chemicals found in mushrooms. In this work, we report the development of a competition-based lateral flow immunoassay (LFIA) for the rapid, portable, selective, and sensitive detection of amatoxins. Our assay clearly indicates the presence of 10 ng/mL of α-AMA or γ-AMA and the method including extraction and detection can be completed in approximately 10 minutes. The test can be easily read by eye and has a presumed shelf-life of at least 1 year. From testing 110 wild mushrooms, the LFIA identified 6 out of 6 species that were known to contain amatoxins. Other poisonous mushrooms known not to contain amatoxins tested negative by LFIA. This LFIA can be used to quickly identify amatoxin-containing mushrooms.

]]>
<![CDATA[Toxin-neutralizing antibodies elicited by naturally acquired cutaneous anthrax are elevated following severe disease and appear to target conformational epitopes]]> https://www.researchpad.co/article/N0733fdcc-4c39-44e4-82cd-032e69d54dbc

Understanding immune responses to native antigens in response to natural infections can lead to improved approaches to vaccination. This study sought to characterize the humoral immune response to anthrax toxin components, capsule and spore antigens in individuals (n = 46) from the Kayseri and Malatya regions of Turkey who had recovered from mild or severe forms of cutaneous anthrax infection, compared to regional healthy controls (n = 20). IgG antibodies to each toxin component, the poly-γ-D-glutamic acid capsule, the Bacillus collagen-like protein of anthracis (BclA) spore antigen, and the spore carbohydrate anthrose, were detected in the cases, with anthrax toxin neutralization and responses to Protective Antigen (PA) and Lethal Factor (LF) being higher following severe forms of the disease. Significant correlative relationships among responses to PA, LF, Edema Factor (EF) and capsule were observed among the cases. Though some regional control sera exhibited binding to a subset of the tested antigens, these samples did not neutralize anthrax toxins and lacked correlative relationships among antigen binding specificities observed in the cases. Comparison of serum binding to overlapping decapeptides covering the entire length of PA, LF and EF proteins in 26 cases compared to 8 regional controls revealed that anthrax toxin-neutralizing antibody responses elicited following natural cutaneous anthrax infection are directed to conformational epitopes. These studies support the concept of vaccination approaches that preserve conformational epitopes.

]]>
<![CDATA[Duplication of clostridial binding domains for enhanced macromolecular delivery into neurons]]> https://www.researchpad.co/article/N57ed6313-35cd-488d-b1d4-47e838d2c373

Neurological diseases constitute a quarter of global disease burden and are expected to rise worldwide with the ageing of human populations. There is an increasing need to develop new molecular systems which can deliver drugs specifically into neurons, non-dividing cells meant to last a human lifetime. Neuronal drug delivery must rely on agents which can recognise neurons with high specificity and affinity. Here we used a recently introduced ‘stapling’ system to prepare macromolecules carrying duplicated binding domains from the clostridial family of neurotoxins. We engineered individual parts of clostridial neurotoxins separately and combined them using a strong alpha-helical bundle. We show that combining two identical binding domains of tetanus and botulinum type D neurotoxins, in a sterically defined way by protein stapling, allows enhanced intracellular delivery of molecules into neurons. We also engineered a botulinum neurotoxin type C variant with a duplicated binding domain which increased enzymatic delivery compared to the native type C toxin. We conclude that duplication of the binding parts of tetanus or botulinum neurotoxins will allow production of high avidity agents which could deliver imaging reagents and large therapeutic enzymes into neurons with superior efficiency.

]]>
<![CDATA[Lean back and wait for the alarm? Testing an automated alarm system for nosocomial outbreaks to provide support for infection control professionals]]> https://www.researchpad.co/article/N4571fdc0-2a2e-4467-acc9-eeadc2652757

Introduction

Outbreaks of communicable diseases in hospitals need to be quickly detected in order to enable immediate control. The increasing digitalization of hospital data processing offers potential solutions for automated outbreak detection systems (AODS). Our goal was to assess a newly developed AODS.

Methods

Our AODS was based on the diagnostic results of routine clinical microbiological examinations. The system prospectively counted detections per bacterial pathogen over time for the years 2016 and 2017. The baseline data covers data from 2013–2015. The comparative analysis was based on six different mathematical algorithms (normal/Poisson and score prediction intervals, the early aberration reporting system, negative binomial CUSUMs, and the Farrington algorithm). The clusters automatically detected were then compared with the results of our manual outbreak detection system.

Results

During the analysis period, 14 different hospital outbreaks were detected as a result of conventional manual outbreak detection. Based on the pathogens’ overall incidence, outbreaks were divided into two categories: outbreaks with rarely detected pathogens (sporadic) and outbreaks with often detected pathogens (endemic). For outbreaks with sporadic pathogens, the detection rate of our AODS ranged from 83% to 100%. Every algorithm detected 6 of 7 outbreaks with a sporadic pathogen. The AODS identified outbreaks with an endemic pathogen were at a detection rate of 33% to 100%. For endemic pathogens, the results varied based on the epidemiological characteristics of each outbreak and pathogen.

Conclusion

AODS for hospitals based on routine microbiological data is feasible and can provide relevant benefits for infection control teams. It offers in-time automated notification of suspected pathogen clusters especially for sporadically occurring pathogens. However, outbreaks of endemically detected pathogens need further individual pathogen-specific and setting-specific adjustments.

]]>
<![CDATA[The validity, reliability and minimal clinically important difference of the patient specific functional scale in snake envenomation]]> https://www.researchpad.co/article/5c8823c4d5eed0c484638faf

Objective

Valid, reliable, and clinically relevant outcome measures are necessary in clinical studies of snake envenomation. The aim of this study was to evaluate the psychometric (validity and reliability) and clinimetric (minimal clinically important difference [MCID]) properties of the Patient-Specific Functional Scale (PSFS) in snakebite envenomation.

Methods

We performed a secondary analysis of two existing snakebite trials that measured clinical outcomes using the PSFS as well as other quality of life and functional assessments. Data were collected at 3, 7, 10, and 17 days. Reliability was determined using Cronbach’s alpha for internal consistency and the intraclass correlation coefficient (ICC) for temporal stability at 10 and 17 days. Validity was assessed using concurrent validity correlating with the other assessments. The MCID was evaluated using the following criteria: (1) the distribution of stable patients according to both standard error of measurement (SEM) and responsiveness techniques, and (2) anchor-based methods to compare between individuals and to detect discriminant ability of a positive change with a receiver operator characteristic (ROC) curve and optimal cutoff point.

Results

A total of 86 patients were evaluated in this study. The average PSFS scores were 5.37 (SD 3.23), 7.95 (SD 2.22), and 9.12 (SD 1.37) at 3, 7, and 10 days, respectively. Negligible floor effect was observed (maximum of 8% at 3 days); however, a ceiling effect was observed at 17 days (25%). The PSFS showed good reliability with an internal consistency of 0.91 (Cronbach’s alpha) (95% CI 0.88, 0.95) and a temporal stability of 0.83 (ICC) (95% CI 0.72, 0.89). The PSFS showed a strong positive correlation with quality of life and functional assessments. The MCID was approximately 1.0 for all methods.

Conclusions

With an MCID of approximately 1 point, the PSFS is a valid and reliable tool to assess quality of life and functionality in patients with snake envenomation.

]]>
<![CDATA[The effect of a transient immune activation on subjective health perception in two placebo controlled randomised experiments]]> https://www.researchpad.co/article/5c8977a8d5eed0c4847d3294

Background

Patient-reported outcomes predict mortality and play increasingly important roles in care, but factors that modify central measures such as health ratings have been little investigated. Building on designated immune-to-brain pathways, we aimed to determine how a short-term induced inflammation response impacts self-reported health status.

Methods

Lipopolysaccharide injections were used to provoke acute systemic inflammatory responses in healthy men and women and were compared to placebo in two double-blind randomized experiments. In Experiment 1, 8 individuals (mean 24 years; SD = 3.7) received lipopolysaccharide 0.8 ng/kg once and placebo once in a cross-over design, and in Experiment 2, 52 individuals received either lipopolysaccharide 0.6 ng/kg or placebo once (28.6 years; SD = 7.1). Main outcomes were perceived health (general and current), sickness behaviour (like fatigue, pain and negative affect), and plasma interleukin-6, interleukin-8 and tumour necrosis factor-α, before and after injection.

Results

Compared to placebo, lipopolysaccharide lead to a deterioration in both self-rated general (Experiment 1, b = 1.88 for 0.8 ng/kg) and current health (Experiment 1 b = -3.00; and Experiment 2 b = -1.79) 1.5h after injection (p’s<0.01), effects that remained after 4.5 to 5 hours (p’s<0.05). The effect on current health in Experiment 2 was mediated by increased inflammation and sickness behaviour in response to lipopolysaccharide injection (β = -0.28, p = 0.01).

Conclusion

Health is drastically re-evaluated during inflammatory activation. The findings are consistent with notions that inflammation forms part of health-relevant interoceptive computations of bodily state, and hint at one mechanism as to why subjective health predicts longevity.

]]>
<![CDATA[Composition of gut microbiota in patients with toxigenic Clostridioides (Clostridium) difficile: Comparison between subgroups according to clinical criteria and toxin gene load]]> https://www.researchpad.co/article/5c76fe10d5eed0c484e5b3f2

Data concerning the human microbiota composition during Clostridioides (Clostridium) difficile infection (CDI) using next-generation sequencing are still limited. We aimed to confirm key features indicating tcdB positive patients and compare the microbiota composition between subgroups based on toxin gene load (tcdB gene) and presence of significant diarrhea. Ninety-nine fecal samples from 79 tcdB positive patients and 20 controls were analyzed using 16S rRNA gene sequencing. Chao1 index for alpha diversity were calculated and principal coordinate analysis was performed for beta diversity using Quantitative Insights into Microbial Ecology (QIIME) pipeline. The mean relative abundance in each group was compared at phylum, family, and genus levels. There were significant alterations in alpha and beta diversity in tcdB positive patients (both colonizer and CDI) compared with those in the control. The mean Chao1 index of tcdB positive patients was significantly lower than the control group (P<0.001), whereas there was no significant difference between tcdB groups and between colonizer and CDI. There were significant differences in microbiota compositions between tcdB positive patients and the control at phylum, family, and genus levels. Several genera such as Phascolarctobacterium, Lachnospira, Butyricimonas, Catenibacterium, Paraprevotella, Odoribacter, and Anaerostipes were not detected in most CDI cases. We identified several changes in the microbiota of CDI that could be further evaluated as predictive markers. Microbiota differences between clinical subgroups of CDI need to be further studied in larger controlled studies.

]]>
<![CDATA[A prospective study of repetition of self-harm following deliberate self-poisoning in rural Sri Lanka]]> https://www.researchpad.co/article/5c6c75cdd5eed0c4843d01ee

Introduction

Repetition of deliberate self-harm is an important predictor of subsequent suicide. Repetition rates in Asian countries appear to be significantly lower than in western high-income countries. Methodological differences in studies, and the impact of access to means of self-harm with comparatively higher lethality have been suggested as reasons for these reported differences. This prospective study determines the rates and demographic patterns of deliberate self-poisoning (DSP), suicide and repeated deliberate self-harm resulting non-fatal and fatal outcomes in rural Sri Lanka.

Methods

Details of DSP admission in all hospitals (n = 46) and suicides reported to all police stations (n = 28) in a rural district were collected for the years 2011, 2012 and 2013. Demographic details of the cohort of patients admitted to all hospitals in 2011 due to deliberate self-poisoning (N = 4022), were screened to link with patient records and police reports of the successive two years with high sensitivity using a computer program. Then high specificity manual matching of all screened links was performed to identify repetition within 2 years of initial presentation. Life time repetition was assessed in a randomly selected subset of DSP patients (n = 433).

Results

There were 15,639 DSP admissions, aged more than 9 years, and 1078 suicides during the study period. The incidence of deliberate self-poisoning and suicide in the population within the study area were 248.3/100,000 and 20.7/100,000 respectively, in 2012. Repetition rates at four weeks, one-year and two-years were 1.9% (95% CI 1.5–2.3%), 5.7% (95% CI 5.0–6.4) and 7.9% (95% CI 7.1–8.8) respectively. The median interval between two attempts were 92 (IQR 10–238) and 191 (IQR 29–419.5) days for the one and two-year repetition groups. The majority of patients used the same poison in the repeat attempt. The age and duration of hospital stay of individuals with repetitive events were not significantly different from those who had no repetitive events. The rate of suicide at two years following DSP was 0.7% (95% CI 0.4–0.9%). The reported life time history of deliberate self-harm attempts was 9.5% (95% CI 6.7–12.2%).

Conclusions

The comparatively low rates of repetition in rural Sri Lanka was not explained by higher rates of suicide, access to more lethal means or differences in study methodology.

]]>
<![CDATA[Carriage and colonization of C. difficile in preterm neonates: A longitudinal prospective study]]> https://www.researchpad.co/article/5c76fe0ed5eed0c484e5b398

Background

Premature neonates (PN) present multiple risk factors for high frequencies and high levels of colonization by C. difficile, yet data is missing about this specific pediatric population. Here, we investigated PN C. difficile carriage and colonization dynamics, analyzed the impact of perinatal determinants on colonization, and characterized the isolates.

Methods

A one year longitudinal monocentric prospective cohort study was performed on 121 PN. C. difficile strains isolated from fecal samples on selective medium were identified and characterized by PCR (tpi housekeeping gene; tcdA and tcdB, and binary toxin genes), capillary gel-based electrophoresis PCR-ribotyping, and Multi-Locus Variable-number tandem-repeat Analysis (MLVA).

Results

Of the 379 samples analyzed, 199 (52%) were C. difficile culture positive with the mean levels of C. difficile colonization decreasing significantly (P = .027) over time. During hospitalization, C. difficile colonization frequency increased up to 61% with 95% of the strains belonging to both non-toxigenic PCR-ribotypes (RTs) FR082 (35%) and 032 (60%). After hospital discharge, if a higher diversity in RTs was observed, RTs FR082 and 032 remained predominant (respectively 40% and 28%). MLVA showed clonal relationship within each FR082 and 032 RTs. Ten toxigenic strains (5%) were isolated, all tcdA+/tcdB+ except for one tcdA-/tcdB+, and all being acquired after hospitalization. At 1 week, the only factors found to be linked with a higher frequency of C. difficile colonization were a higher gestational age (P = 0.006) and a higher birth weight (P = 0.016).

Conclusion

The dynamics of C. difficile colonization in PN followed a specific pattern. C. difficile colonization rapidly occurred after birth with a low diversity of non-toxigenic RTs. After hospitalization, non-toxigenic RTs diversity increased. Sporadic carriage of toxigenic strains was observed after hospitalization.

]]>
<![CDATA[Evidence of transmission of Clostridium difficile in asymptomatic patients following admission screening in a tertiary care hospital]]> https://www.researchpad.co/article/5c6b262bd5eed0c4842894b4

Background

Clostridium difficile (CD) is the leading cause of infectious health-care associated diarrhea. However, little is known regarding CD carriage and transmission amongst asymptomatic colonizers. We evaluated carriage, characterized strains and examined epidemiologic linkages in asymptomatic colonized CD patients.

Methods

Rectal swabs from asymptomatic patients admitted to the general medicine ward from April 1-June 30 2012 were collected. PCR-confirmed CD colonies were ribotyped and characterized by Modified-Multi Locus Variable Number Tandem Repeat Analysis (MMLVA).

Results

1549-swabs were collected from 474-patients. Overall, 50/474(10.6%) were CD PCR-positive, 24/50 were colonized at admission, while 26/50 were first identified > = 72 hours after admission. Amongst the 50 CD PCR-positive patients, 90% were asymptomatically colonized and 80% of individuals carried toxigenic CD-strains, including ribotype-027 (5/45:11%). MMLVA revealed five-clusters involving 15-patients harboring toxigenic (4/5) and non-toxigenic CD strains (1/5). In two clusters, patients were CD positive on admission while in the other three clusters involving 10 patients, we observed CD transmission from asymptomatically colonized patients to 8 previously CD-negative patients.

Conclusions

We identified increasing rates of colonization during admission to medical wards. MMLVA typing effectively discriminated between strains and suggests that 20% of patients with CD colonization acquired their strain(s) from asymptomatically colonized individuals in hospital.

]]>
<![CDATA[Synthesis of MnCo2O4 nanoparticles as modifiers for simultaneous determination of Pb(II) and Cd(II)]]> https://www.researchpad.co/article/5c648ce7d5eed0c484c81a65

The porous spinel oxide nanoparticles, MnCo2O4, were synthesized by citrate gel combustion technique. Morphology, crystallinity and Co/Mn content of modified electrode was characterized and determined by Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction pattern analysis (XRD), simultaneous thermogravimetry and differential thermal analysis (TG/DTA). Nanoparticles were used for modification of glassy carbon electrode (GCE) and new sensor was applied for simultaneous determination of Pb(II) and Cd(II) ions in water samples with the linear sweep anodic stripping voltammetry (LSASV).The factors such as pH, deposition potential and deposition time are optimized. Under optimal conditions the wide linear concentration range from 0.05 to 40 μmol/dm3was obtained for Pb(II), with limit of detection (LOD) of 8.06 nmol/dm3 and two linear concentration ranges were obtained for Cd(II), from 0.05 to 1.6 μmol/dm3 and from 1.6 to 40 μmol/dm3, with calculated LOD of 7.02 nmol/dm3. The selectivity of the new sensor was investigated in the presence of interfering ions. The sensor is stable and it gave reproducible results. The new sensor was succesfully applied on determination of heavy metals in natural waters.

]]>
<![CDATA[Mechanisms underpinning the permanent muscle damage induced by snake venom metalloprotease]]> https://www.researchpad.co/article/5c59febed5eed0c484135375

Snakebite is a major neglected tropical health issue that affects over 5 million people worldwide resulting in around 1.8 million envenomations and 100,000 deaths each year. Snakebite envenomation also causes innumerable morbidities, specifically loss of limbs as a result of excessive tissue/muscle damage. Snake venom metalloproteases (SVMPs) are a predominant component of viper venoms, and are involved in the degradation of basement membrane proteins (particularly collagen) surrounding the tissues around the bite site. Although their collagenolytic properties have been established, the molecular mechanisms through which SVMPs induce permanent muscle damage are poorly understood. Here, we demonstrate the purification and characterisation of an SVMP from a viper (Crotalus atrox) venom. Mass spectrometry analysis confirmed that this protein is most likely to be a group III metalloprotease (showing high similarity to VAP2A) and has been referred to as CAMP (Crotalus atrox metalloprotease). CAMP displays both collagenolytic and fibrinogenolytic activities and inhibits CRP-XL-induced platelet aggregation. To determine its effects on muscle damage, CAMP was administered into the tibialis anterior muscle of mice and its actions were compared with cardiotoxin I (a three-finger toxin) from an elapid snake (Naja pallida) venom. Extensive immunohistochemistry analyses revealed that CAMP significantly damages skeletal muscles by attacking the collagen scaffold and other important basement membrane proteins, and prevents their regeneration through disrupting the functions of satellite cells. In contrast, cardiotoxin I destroys skeletal muscle by damaging the plasma membrane, but does not impact regeneration due to its inability to affect the extracellular matrix. Overall, this study provides novel insights into the mechanisms through which SVMPs induce permanent muscle damage.

]]>
<![CDATA[Historical observations of algal blooms in Mazatlan Bay, Sinaloa, Mexico (1979-2014)]]> https://www.researchpad.co/article/5c5b529ad5eed0c4842bcc8c

A 35-year record of algal blooms in Mazatlan Bay is reviewed in order to register bloom-forming species and their seasonal presence, duration, degree of toxicity and environmental impact. A total of 202 algal blooms have been recorded and 25 dominant species identified: 6 toxic, 5 harmful and 14 harmless species. A harmless species, Myrionecta rubra, tended to decrease in frequency, while toxic species Gymnodinium catenatum and Margalefidinium polykrikoides showed a clear trend towards an increase in frequency. The number of discoloration days attributable to blooms was highly variable in each year, but a decadal analysis revealed a tendency to increase. The monthly distribution of algal blooms for decades showed two peaks of high frequency, the larger from February to May and the smaller from September to November. The duration of blooms varied from a few days to more than three months; the ephemeral blooms were the most frequent, but in the last decade, the frequency of the longer-lasting blooms has increased. An absence of blooms in 1983–4 and 1992–3 coincided with strong El Niño events, but this pattern was not consistent in subsequent El Niño years. Years with more or fewer discolorations days appear to be associated with cold or warm phases of the Pacific Decadal Oscillation.

]]>
<![CDATA[A single alcohol binge impacts on neutrophil function without changes in gut barrier function and gut microbiome composition in healthy volunteers]]> https://www.researchpad.co/article/5c5df322d5eed0c484580d6e

Alcohol binge drinking is a dangerous drinking habit, associated with neurological problems and inflammation. The impact of a single alcohol binge on innate immunity, gut barrier and gut microbiome was studied. In this cohort study 15 healthy volunteers received 2 ml vodka 40% v/v ethanol/kg body weight. Neutrophil function was studied by flow cytometry; markers of gut permeability and inflammation (lactulose/mannitol/sucrose test, zonulin, calprotectin, diamino-oxidase) were studied with NMR spectroscopy and enzyme-linked immunosorbent assay in urine, stool and serum respectively. Bacterial products in serum were quantified using different reporter cell lines. Gut microbiome composition was studied by 16S rDNA sequencing and bioinformatics analysis. After a single alcohol binge, neutrophils were transiently primed and the response to E.coli stimulation with reactive oxygen species (ROS) production was transiently increased, on the other hand the percentage of neutrophils that did not perform phagocytosis increased. No changes in gut permeability, inflammatory biomarker, bacterial translocation and microbiome composition could be detected up to 4 hours after a single alcohol binge or on the next day. A single alcohol binge in young, healthy volunteers transiently impacts on neutrophil function. Although the exact biological consequence of this finding is not clear yet, we believe that this strengthens the importance to avoid any alcohol binge drinking, even in young, otherwise healthy persons.

]]>
<![CDATA[Reporting of “dialysis adequacy” as an outcome in randomised trials conducted in adults on haemodialysis]]> https://www.researchpad.co/article/5c633962d5eed0c484ae65b8

Background

Clinical trials are most informative for evidence-based decision-making when they consistently measure and report outcomes of relevance to stakeholders, especially patients, clinicians, and policy makers. However, sometimes terminology used is interpreted differently by different stakeholders, which might lead to confusion during shared decision making. The construct dialysis adequacy is frequently used, suggesting it is an important outcome both for health care professionals as for patients.

Objective

To assess the scope and consistency of the construct dialysis adequacy as reported in randomised controlled trials in hemodialysis, and evaluate whether these align to the insights and understanding of this construct by patients.

Methods

To assess scope and consistency of dialysis adequacy by professionals, we performed a systematic review searching the Cochrane Central Register of Controlled Trials (CENTRAL) up to July 2017. We identified all randomised controlled trails (RCT) including patients on hemodialysis and reporting dialysis adequacy, adequacy or adequacy of dialysis and extracted and classified all reported outcomes. To explore interpretation and meaning of the construct of adequacy by patients, we conducted 11 semi-structured interviews with HD patients using thematic analysis. Belgian registration number B670201731001.

Findings

From the 31 included trials, we extracted and classified 98 outcome measures defined by the authors as adequacy of dialysis, of which 94 (95%) were biochemical, 3 (3%) non-biochemical surrogate and 2 (2%) patient-relevant. The three most commonly reported measures were all biochemical. None of the studies defined adequacy of dialysis as a patient relevant outcome such as survival or quality of life. Patients had a substantially different understanding of the construct dialysis adequacy than the biochemical interpretation reported in the literature. Being alive, time spent while being on dialysis, fatigue and friendliness of staff were the most prominent themes that patients linked to the construct of dialysis adequacy.

Conclusion

Adequacy of dialysis as reported in the literature refers to biochemical outcome measures, most of which are not related with patient relevant outcomes. For patients, adequate dialysis is a dialysis that enables them to spend as much quality time in their life as possible.

]]>
<![CDATA[Impact of CodY protein on metabolism, sporulation and virulence in Clostridioides difficile ribotype 027]]> https://www.researchpad.co/article/5c5b52e7d5eed0c4842bd237

Toxin synthesis and endospore formation are two of the most critical factors that determine the outcome of infection by Clostridioides difficile. The two major toxins, TcdA and TcdB, are the principal factors causing damage to the host. Spores are the infectious form of C. difficile, permit survival of the bacterium during antibiotic treatment and are the predominant cell form that leads to recurrent infection. Toxin production and sporulation have their own specific mechanisms of regulation, but they share negative regulation by the global regulatory protein CodY. Determining the extent of such regulation and its detailed mechanism is important for understanding the linkage between two apparently independent biological phenomena and raises the possibility of creating new ways of limiting infection. The work described here shows that a codY null mutant of a hypervirulent (ribotype 027) strain is even more virulent than its parent in a mouse model of infection and that the mutant expresses most sporulation genes prematurely during exponential growth phase. Moreover, examining the expression patterns of mutants producing CodY proteins with different levels of residual activity revealed that expression of the toxin genes is dependent on total CodY inactivation, whereas most sporulation genes are turned on when CodY activity is only partially diminished. These results suggest that, in wild-type cells undergoing nutrient limitation, sporulation genes can be turned on before the toxin genes.

]]>
<![CDATA[Lapachol and synthetic derivatives: in vitro and in vivo activities against Bothrops snake venoms]]> https://www.researchpad.co/article/5c58d640d5eed0c4840319be

Background

It is known that local tissue injuries incurred by snakebites are quickly instilled causing extensive, irreversible, tissue destruction that may include loss of limb function or even amputation. Such injuries are not completely neutralized by the available antivenins, which in general are focused on halting systemic effects. Therefore it is prudent to investigate the potential antiophidic effects of natural and synthetic compounds, perhaps combining them with serum therapy, to potentially attenuate or eliminate the adverse local and systemic effects of snake venom. This study assessed a group of quinones that are widely distributed in nature and constitute an important class of natural products that exhibit a range of biological activities. Of these quinones, lapachol is one of the most important compounds, having been first isolated in 1882 from the bark of Tabebuia avellanedae.

Methodology/Principal findings

It was investigated the ability of lapachol and some new potential active analogues based on the 2-hydroxi-naphthoquinone scaffold to antagonize important activities of Bothrops venoms (Bothrops atrox and Bothrops jararaca) under different experimental protocols in vitro and in vivo. The bioassays used to test the compounds were: procoagulant, phospholipase A2, collagenase and proteolytic activities in vitro, venom-induced hemorrhage, edematogenic, and myotoxic effects in mice. Proteolytic and collagenase activities of Bothrops atrox venom were shown to be inhibited by lapachol and its analogues 3a, 3b, 3c, 3e. The inhibition of these enzymatic activities might help to explain the effects of the analogue 3a in vivo, which decreased skin hemorrhage induced by Bothrops venom. Lapachol and the synthetic analogues 3a and 3b did not inhibit the myotoxic activity induced by Bothrops atrox venom. The negative protective effect of these compounds against the myotoxicity can be partially explained by their lack of ability to effectively inhibit phospholipase A2 venom activity. Bothrops atrox venom also induced edema, which was significantly reduced by the analogue 3a.

Conclusions

This research using a natural quinone and some related synthetic quinone compounds has shown that they exhibit antivenom activity; especially the compound 3a. The data from 3a showed a decrease in inflammatory venom effects, presumably those that are metalloproteinase-derived. Its ability to counteract such snake venom activities contributes to the search for improving the management of venomous snakebites.

]]>