Mechanism of action of pseudopteroxazole and pseudopterosin G: Diterpenes from marine origin

Pseudopteroxazole (Ptx) and the pseudopterosins are marine natural products with promising antibacterial potential. While Ptx has attracted interest for its antimycobacterial activity, pseudopterosins are active against several clinically relevant pathogens. Both compound classes exhibit low cytotoxicity and accessibility to targeted synthesis, yet their antibacterial mechanisms remain elusive. In this study, we investigated the modes of action of Ptx and pseudopterosin G (PsG) in Bacillus subtilis employing an unbiased approach that combines gel-based proteomics with a mathematical similarity analysis of response profiles. Proteomic responses to sublethal concentrations of Ptx and PsG were compared to a library of antibiotic stress response profiles revealing that both induce a stress response characteristic for agents targeting the bacterial cell envelope by interfering with membrane-bound steps of cell wall biosynthesis. Microscopy-based assays confirmed that both compounds compromise the integrity of the bacterial cell wall without disrupting the membrane potential. Furthermore, LC-MSE analysis showed that the greater potency of PsG against B. subtilis, reflected in a lower MIC and a more pronounced proteomic response, may be rooted in a more effective association with and penetration of B. subtilis cells. We conclude that Ptx and PsG target the integrity of the gram-positive cell wall.

The impact of COVID-19 public health measures on attendance and overdose at supervised injecting facilities in Australia

OBJECTIVES

The COVID-19 pandemic disrupted service provision of harm reduction and drug treatment services for people who inject drugs in many countries. The two supervised injecting facilities (SIFs) in Sydney and Melbourne were differentially impacted by the pandemic, requiring local procedural changes in each service. We aimed to examine the impact of pandemic responses (including restrictions on movement, known as 'lockdowns') on service use and key parameters such as client reports of drug injected and recorded overdose rates.

STUDY DESIGN

Time series analysis of weekly client visits and monthly overdoses occurring at each service.

METHODS

Administrative client data from the two SIFs (Sydney data from 1 January 2018 to 30 April 2022; Melbourne data from 1 July 2018 to 30 April 2022) were examined using interrupted time series analyses with lockdown dates in each state entered as interruption terms. We analysed weekly SIF visits overall and by drug type, and monthly rates of opioid overdose at each service.

RESULTS

Lockdowns resulted in decreased visits to both services. The number of weekly client visits decreased during the first national lockdown for both the Sydney (trend change = -57.9; 95% CI [-109.4, -6.4]) and Melbourne SIF (near sig trend change = -54.8 [-110.8, 1.05]). Trends in visit numbers increased after lockdowns were lifted in each city; however, visits in Sydney have not returned to the numbers recorded prior to the pandemic. Visits to the Melbourne SIF related to heroin use declined at each lockdown (trend 1 = -42.7 [-81.5, -3.9]; trend 2 = -56.1 [-94.6, -17.7]; trend 3 = -33.8 [-67.4, -0.2]); heroin visits to the Sydney SIF declined during the first lockdown and remained low (trend = -55.6 [-82.8, -28.3]). Methamphetamine visits to the Sydney SIF fluctuated, surpassing heroin visits at several timepoints. Rates of monthly opioid overdoses at both services declined immediately following the start of the first lockdown (Sydney = -16.6 [-26.1, -6.8]; Melbourne = -6.4 [-8.7, -4.1]), with increasing trends recorded at the end of the final lockdown in each jurisdiction (Sydney = 2.8 [0.6, 5.0]; Melbourne = 1.3 [0.72, 3.2]).

CONCLUSIONS

Public health restrictions related to the COVID-19 pandemic were associated with reduced client visits to, and overdoses in, Australian SIFs. Variations were noted in the drugs injected, likely reflecting changes in local drug markets. Shifts to other drugs during these periods were evident: methamphetamine in Sydney; co-injection of heroin and diphenhydramine in Melbourne.

Does sexuality matter? A cross-sectional study of drug use, social injecting, and access to injection-specific care among men who inject drugs in Melbourne, Australia

BACKGROUND

Gay, bisexual and other men who have sex with men (GBMSM) are overrepresented in cohorts of people who inject drugs. GBMSM's substance use is usually explored in the context of its contribution to sexual risk. We examined drug use practices, connectedness to other people who inject drugs, peer-to-peer injecting, and access to care among men who inject drugs in Melbourne, Australia. We aim to describe similarities and differences in these parameters for GBMSM and other men.

METHODS

Data were drawn from a prospective cohort study of people who inject drugs conducted in Melbourne, Australia, since 2009. This cross-sectional study used data collected between 2016 and 2021. Descriptive statistics were used to assess differences between GBMSM and other men.

RESULTS

Of 525 men who injected drugs over the study period, 48 (9%) identified as gay or bisexual, or reported sex with other men in the past 12 months. GBMSM and other men reported similar socio-demographics, drug practices (age of injecting initiation, most injected drug, peer-to-peer injecting, receptive syringe sharing) and access to injecting-specific care (drug treatment, source of needle-syringes). A significantly greater percentage of GBMSM reported past 12-month hepatitis C testing (69% vs. 52%, p = 0.028) and preferring methamphetamine (31% vs. 16%, p = 0.022). A higher percentage of GBMSM reported knowing > 50 other people who inject drugs (46% vs. 37%), but this difference was not statistically significant. Both groups primarily obtained injecting equipment from needle-syringe programs; a minority had accessed injecting-specific primary care.

CONCLUSION

Men who injected drugs in this cohort and those who identified as GBMSM reported similar drug and health-seeking practices. The higher prevalence of methamphetamine injecting among GBMSM may warrant different harm reduction support for this group. Health promotion should utilise opportunities to connect men who inject drugs in Melbourne to injecting-specific primary health care.

Label-Free Quantitation of Ribosomal Proteins from Bacillus subtilis for Antibiotic Research

Current research is focusing on ribosome heterogeneity as a response to changing environmental conditions and stresses. Altered stoichiometry and composition of ribosomal proteins as well as association of additional protein factors are mechanisms for shaping the protein expression profile or hibernating ribosomes. In this updated chapter, we present a method for the isolation of ribosomes to analyze antibiotic-induced changes in the composition of ribosomes in Bacillus subtilis or other bacteria. Ribosomes and associated proteins are isolated by ultracentrifugation, and proteins are identified and quantified using label-free mass spectrometry.

Trust and service engagement among people who inject drugs after release from prison

BACKGROUND

Compounding histories of injecting drug use and incarceration can marginalise people engaging with services, making it difficult for them to address their health and social welfare needs, particularly when they navigate community re-entry service supports. Drawing on Hall and colleagues' five components of trust, this paper seeks to understand how trust in service providers fosters (or inhibits) effective service engagement from the perspective of people who inject drugs during the prison post-release period.

METHODS

Between September 2018 and May 2020, qualitative in-depth interviews were completed with 48 adults (33 men, 15 women) recruited from SuperMIX (a longitudinal cohort study of people with a history of injection drug use in Victoria, Australia). Data relating to service engagement were coded against the five components of trust: competence, fidelity, honesty, global trust, and confidence.

RESULTS

Reflections of post-release service engagement frequently focused on interactions with community corrections (parole) officers. Depictions of trust were consistently portrayed within the context of negative experiences and deficits, whereby trusting provider relationships and interactions were rarely described. Most participants recounted a stark absence of fidelity (that is, "pursuing a [client's] best interests"), with some participants detailing circumstances in which their vulnerability was purposefully, almost strategically, exploited. These encounters nearly always had the consequence of impeding the participant's positive progression in the post-release integration period.

CONCLUSION

There is an urgent need to prioritise the client in health and social service delivery in the post-release transition-to-community period and recognise the importance of trust in delivering effective services to people whose life histories make them highly vulnerable to marginalisation.

Effects of 4-Br-A23187 on Bacillus subtilis cells and unilamellar vesicles reveal it to be a potent copper ionophore

Ionophores are small molecules or peptides that transport metal ions across biological membranes. Their transport capabilities are typically characterized in vitro using vesicles and single ion species. It is difficult to infer from these data which effects ionophores have on living cells in a complex environment (e.g. culture medium), since net ion movement is influenced by many factors including ion composition of the medium, concentration gradients, pH gradient, and protein-mediated transport processes across the membrane. To gain insights into the antibacterial mechanism of action of the semisynthetic polyether ionophore 4-Br-A23187, known to efficiently transport zinc and manganese in vitro, we investigated its effects on the gram-positive model organism Bacillus subtilis. In addition to monitoring cellular ion concentrations, the physiological impact of treatment was assessed on the proteome level. 4-Br-A23187 treatment resulted in an increase in intracellular copper levels, the extent of which depended on the copper concentration of the medium. Effects of copper accumulation mirrored by the proteomic response included oxidative stress, disturbance of proteostasis, metal and sulfur homeostasis. The antibiotic effect of 4-Br-A23187 is further aggravated by a decrease in intracellular manganese and magnesium. A liposome model confirmed that 4-Br-A23187 acts as copper ionophore in vitro. This article is protected by copyright. All rights reserved.

Zwitterionic Peptides Reduce Accumulation of Marine and Freshwater Biofilm Formers

Zwitterionic peptides are facile low-fouling compounds for environmental applications as they are biocompatible and fully biodegradable as their degradation products are just amino acids. Here, a set of histidine (H) and glutamic acid (E), as well as lysine (K) and glutamic acid (E) based peptide sequences with zwitterionic properties were synthesized. Both oligopeptides (KE)₄K and (HE)₄H were synthesized in d and l configurations to test their ability to resist the nonspecific adsorption of the proteins lysozyme and fibrinogen. The coatings were additionally tested against the attachment of the marine organisms Navicula perminuta and Cobetia marina as well as the freshwater bacterium Pseudomonas fluorescens on the developed coatings. While the peptides containing lysine performed better in protein resistance assays and against freshwater bacteria, the sequences containing histidine were generally more resistant against marine organisms. The contribution of amino acid-intrinsic properties such as side chain pK_a values and hydrophobicity, as well as external parameters such as pH and salinity of fresh water and seawater on the resistance of the coatings is discussed. In this way, a detailed picture emerges as to which zwitterionic sequences show advantages in future generations of biocompatible, sustainable, and nontoxic fouling release coatings.

Evaluation of Ruthenium(II) N-Heterocyclic Carbene Complexes as Antibacterial Agents and Inhibitors of Bacterial Thioredoxin Reductase

A series of ruthenium(II) complexes with N-heterocyclic carbene (NHC) ligands of the general type (arene)(NHC)Ru(II)X2 (where X = halide) was prepared, characterized, and evaluated as antibacterial agents in comparison to the respective metal free benzimidazolium cations. The ruthenium(II) NHC complexes generally triggered stronger bacterial growth inhibition than the metal free benzimidazolium cations. The effects were much stronger against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) than against Gram-negative bacteria (Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa), and all complexes were inactive against the fungus Candida albicans. Moderate inhibition of bacterial thioredoxin reductase was confirmed for selected complexes, indicating that inhibition of this enzyme might be a contributing factor to the antibacterial effects.

Workplace intervention programmes for decreasing alcohol use in military personnel: a systematic review

INTRODUCTION

Harmful or risky-single occasion drinking (RSOD) alcohol use in the military is a significant problem. However, most studies of interventions have focused on veterans, representing a missed opportunity for intervention with active military personnel. Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) framework, the aim of this systematic review was to analyse and synthesise the evidence related to workplace-based interventions for reducing alcohol use in active-duty military personnel.

METHODS

Four electronic databases and reference lists of relevant articles were searched from database inception until 20 January 2020. This review focused on experimental and quasi-experimental studies of active-duty military personnel. Data extraction and methodological quality assessment were independently performed by two reviewers using a standardised checklist. A third reviewer was used to arbitrate the disputed studies for final selection.

RESULTS

The search yielded seven studies from an initial 1582 records identified. A range of interventions were used in these studies (four randomised controlled trials, two non-randomised trials and one before and after cohort study), including web-based approaches, telephone-delivered interventions and individual and group-based face-to-face interventions. Seven studies found decreased drinking, measured using a range of outcomes, following the intervention. However, this was not sustained in the longer term in any of the studies.

CONCLUSIONS

The low methodological rigour of most studies limited the capacity to demonstrate the efficacy of the interventions studied. Given the importance of reducing harmful or RSOD use of alcohol in the military, future studies would benefit from improved methodological rigour including ensuring adequate study power, randomisation, selection of validated outcome measures, including measures other than consumption (eg, attitudinal measures), and longer-term follow-up. There is also a need to develop methods that ensure participant loss to follow-up is minimised.

Assessing individual-level needle and syringe coverage parameters and the measurement of coverage in Melbourne, Australia: methods and impacts

Background

To assess the structure of individual-level needle and syringe coverage measurement formula, and to estimate the impact of coverage-related behaviours/parameters (instances of syringe acquisition, total syringes acquired, peer-to-peer syringe distribution, injecting frequency) on overall coverage.

Methods

Data are drawn from the Melbourne (Australia) injecting drug user cohort study, 2010-16. Data from 518 participants were analysed. We used correlations to explore the relationships between coverage parameters; pooled multiple-linear regression to estimate the effect of each parameter on coverage over time; and exploratory factor analysis to assess the relevance of each parameter within the coverage formula.

Results

A 1-unit increase in injecting frequency over time reduced coverage by 10.93 percentage points, almost twice as much as other coverage parameters. Factor analysis results indicated potential improvements to coverage formula structure.

Conclusions

Our results suggest that reducing injecting frequency amongst people who inject drugs has the largest improvement in coverage levels, indicating harm reduction services should prioritize it. We also demonstrate that coverage measurement has been inconsistent to date. We sought to refine the method to assist in generating comparable research.

Comparing short versions of the Alcohol Use Disorders Identification Test (AUDIT) in a military cohort

Background

The Alcohol Use Disorders Identification Test (AUDIT) is widely used for monitoring harmful alcohol consumption among high-risk populations. A number of short versions of AUDIT have been developed for use in time-constrained settings. In military populations, a range of AUDIT variations have been used, but the optimal combination of AUDIT items has not been determined.

Methods

A total of 952 participants (80% male), recruited as part of a wider study, completed the AUDIT-10. We systematically assessed all possible combinations of three or four AUDIT items and established AUDIT variations using the following statistics: Cronbach’s alpha (internal consistency), variance explained (R2) and Pearson’s correlation coefficient (concurrent validity).

Results

Median AUDIT-10 score was 7 for males and 6 for females, and 380 (40%) participants were classified as having a score indicative of harmful or hazardous alcohol use (≥8) according to WHO classifications.

A novel four-item AUDIT variation (3, 4, 8 and 9) performed consistently higher than established variations across statistical measures; it explained 85% of variance in AUDIT-10, had a Pearson’s correlation of 0.92 and Cronbach’s alpha was 0.63. The FAST, an established shortened AUDIT variant, together with several other four-item novel variants of AUDIT-10 performed similarly. The AUDIT-C performed consistently low on all measures, but with a satisfactory level of internal consistency (75%).

Conclusion

Shortened AUDIT variations may be suitable alternatives to the full AUDIT for screening hazardous alcohol consumption in military populations. Four-item AUDIT variations focused on short-term risky drinking and its consequences performed better than three item versions.

Trial registration number

ACTRN12614001332617.

Injecting drug use in low and middle-income countries: Opportunities to improve care and prevent harm

Inadequate response to injecting drug use (IDU) is a significant problem the world over. Low levels of funding, political inaction, poor levels of health service coverage, high prevalence and incidence of IDU-related blood-borne viruses (BBVs) and ongoing stigmatization/marginalization affect people who inject drugs (PWID) regardless of the income status of the country they reside in. These barriers and system failings are, however, exacerbated in low and middle-income countries (LMICs), meaning that the potential consequences of inaction are more pressing. In this narrative review, we describe the levels of IDU and IDU-specific BBV prevalence in LMICs; levels of harm reduction implementation; the consequences of late or insufficient response, the shortcomings of data collection and dissemination; and the barriers to effective LMIC harm reduction implementation. We also exemplify cases where IDU-related harms and BBV epidemics have been successfully curtailed in LMICs, showing that effective response, despite the barriers, is possible. In conclusion, we suggest four key priorities on the basis of the review: confirming the presence or absence of IDU in LMICs, improving the collection and dissemination of national IDU-specific data, increasing the level of harm reduction programme implementation in LMICs, and increasing both national and international advocacy for PWID and attendant public health interventions.

The relationship between age and risky injecting behaviours among a sample of Australian people who inject drugs

BACKGROUND

Limited evidence suggests that younger people who inject drugs (PWID) engage in high-risk injecting behaviours. This study aims to better understand the relationships between age and risky injecting behaviours.

METHODS

Data were taken from 11 years of a repeat cross-sectional study of sentinel samples of regular PWID (The Australian Illicit Drug Reporting System, 2001-2011). Multivariable Poisson regression was used to explore the relationship between age and four outcomes of interest: last drug injection occurred in public, receptive needle sharing (past month), experiencing injecting-related problems (e.g. abscess, dirty hit; past month), and non-fatal heroin overdose (past six months).

RESULTS

Data from 6795 first-time study participants were analysed (median age: 33 years, interquartile range [IQR]: 27-40; median duration of injecting: 13 years [IQR: 7-20]). After adjusting for factors including duration of injecting, each five year increase in age was associated with significant reductions in public injecting (adjusted incidence rate ratio [AIRR]: 0.90, 95% confidence interval [CI]: 0.88-0.92), needle sharing (AIRR: 0.84, 95% CI: 0.79-0.89) and injecting-related problems (AIRR: 0.96, 95% CI: 0.95-0.97). Among those who had injected heroin in the six months preceding interview, each five year increase in age was associated with an average 10% reduction in the risk of heroin overdose (AIRR: 0.90, 95% CI: 0.85-0.96).

CONCLUSIONS

Older PWID report significantly lower levels of high-risk injecting practices than younger PWID. Although they make up a small proportion of the current PWID population, younger PWID remain an important group for prevention and harm reduction.

Associations between alcohol related hospital admissions and alcohol consumption in Victoria: influence of socio-demographic factors

OBJECTIVE

To examine the cross-sectional ecologic associations between apparent per-capita alcohol consumption, alcohol-related hospital admission rates, and the distributions of socio-demographic factors for people residing in 76 Local Government Areas (LGAs) in Victoria, during the 1995-1996 fiscal year.

METHOD

Visitor-adjusted per-capita alcohol consumption was obtained from wholesale sales data from the Liquor Licensing Commission Victoria. Alcohol-related hospital admission rates were extracted from the Victorian Inpatient Minimum Dataset, and adjusted by the appropriate aetiologic fractions. Summary socio-demographic measures were derived from the 1996 Census. Their associations were analysed using multiple linear regression.

RESULTS

Per-capita alcohol consumption ranged from 4 to 14 litres absolute alcohol/year and alcohol-related hospital admission rates ranged from 5 to 25 per 10,000 residents/year (external-cause diagnoses) and 8-37 per 10,000 residents/year (disease diagnoses). Higher levels of per-capita consumption were associated with higher admission rates (r = 0.45 for external cause diagnoses, r = 0.66 for disease diagnoses, and r = 0.70 for all diagnoses), each per-capita increase of one litre/year corresponding to increased admission rates of 0.6, 1.5 and 2.1 per 10,000 person-years, respectively. Further adjustments by summary socio-demographic measures reduced, but did not modify, the associations between per-capita consumption and admission rates.

CONCLUSIONS AND IMPLICATIONS

Summary measures of sales-based per-capita alcohol consumption and socio-demographic environments may provide useful indicators of alcohol-related morbidity in Victorian communities.

TRANSFAC, TRRD and COMPEL: towards a federated database system on transcriptional regulation

Three databases that provide data on transcriptional regulation are described. TRANSFAC is a database on transcription factors and their DNA binding sites. TRRD (Transcription Regulatory Region Database) collects information about complete regulatory regions, their regulation properties and architecture. COMPEL comprises specific information on composite regulatory elements. Here, we describe the present status of these databases and the first steps towards their federation.

TRANSFAC: a database on transcription factors and their DNA binding sites

TRANSFAC is a database about eukaryotic transcription regulating DNA sequence elements and the transcription factors binding to and acting through them. This report summarizes the present status of this database and accompanying retrieval tools.

TRANSFAC retrieval program: a network model database of eukaryotic transcription regulating sequences and proteins

DNA sequences that are involved in the control of gene expression in eukaryotes have been collected in conjunction with the proteins binding to and acting through them (TRANSFAC data set). To make these data accessible, the TRANSFAC retrieval program (TRP) has been developed as a database management system which is based upon the network model. This database model possesses particular advantages for data management of a complex structure. The aim of TRP is to provide an easily handled statistical basis for a computational approach to transcription control.