Impacts of COVID-19 on Young Children and Families: A Qualitative Study Using Best Starts for Kids Health Survey Data in King County, WA

OBJECTIVES

To evaluate the impacts of the COVID-19 pandemic on parents and caregivers with young children in King County, Washington using data from a local population-based survey, the Best Starts for Kids Health Survey (BSKHS).

METHODS

7033 parents and caregivers in King County, Washington with children 5th grade and younger participated in the BSKHS in 2021. Three evaluators adopted a framework method approach to thematic analysis for open-ended survey responses regarding the impacts of COVID-19 on families.

RESULTS

Children aged 0-5 years missed important social development opportunities, while elementary-school children missed social interactions and felt isolated during remote schooling. Parents were exhausted by the competing demands of work and schooling/childcare, with mothers bearing the brunt of additional responsibilities. Many families faced financial uncertainty and were unable to meet basic needs. Yet, families were grateful for more quality time with family members.

CONCLUSIONS FOR PRACTICE

Parents expressed that children aged 0-5 years missed out on social development opportunities with both adults and children their own age and elementary-school children and felt isolated while schools were closed to in-person schooling.

The "Monsanto papers" and the nature of ghostwriting and related practices in contemporary peer review scientific literature

The Monsanto company - now acquired by Bayer - has been accused of ghostwriting articles within peer review literature, with the goal of using influential names to front its content in defence of the herbicide Roundup. Here, I conduct a detailed analysis of three Monsanto review articles and a five-article journal supplement for which detailed information from company emails is publicly available following litigation over Roundup. All the articles had external, but not Monsanto authors, and ghostly practices including ghost authorship, corporate ghost authorship and ghost management were evident in their development. There was clear evidence of ghostwriting - that is, drafting of the manuscript by non-authors - in only two cases. I found no evidence of undeserving authorship among the external authors. The articles complied with the disclosure requirements of their journals, save for the journal supplement. While crude ghostwriting did occur, much of the literature involved subtler practices through which Monsanto exercised control over content, while the attribution of the articles downplayed the company's role - and correspondingly aggrandized that of the external authors. Such practices are widespread within industry journal literature and are the responsibility of byline authors and journals as well as corporations. I discuss these cultural problems and consider remedies.

Attribution and credit bias in publication ethics

In this article, I argue that many of the ethical problems associated with the authorship of journal literature can usefully be clarified if authorship is placed within the broader concept of attribution, which extends beyond the author byline to encompass everything that readers are told about the work's origination and the parties responsible. I also suggest that as the attribution of literature has grown more complex, and the opportunities for misattribution have become more subtle and multifarious, attribution has become increasingly vulnerable to systematic bias. Accordingly, I define "credit bias" as the systematic distortion of attribution, frequently in the interests of those with influence over the publication. I present a four-step framework for evaluating publications, discuss misattribution in drug industry literature as an illustration of credit bias, and examine the role of editorial standards in mitigating, but also in assisting, credit bias. I also argue for an independent scientific standard to promote ethical conduct in the medical journal sector.

Clinical Trial Endpoints in Metastatic Cancer: Using Individual Participant Data to Inform Future Trials Methodology

Meta-analysis based on individual participant data (IPD) is a powerful methodology for synthesizing evidence by combining information drawn from multiple trials. Hitherto, its principal application has been in questions of clinical management, but an increasingly important use is in clarifying trials methodology, for instance in the selection of endpoints, as discussed in this review. In oncology, the Aide et Recherche en Cancérologie Digestive (ARCAD) Metastatic Colorectal Cancer Database is a leader in the use of IPD-based meta-analysis in methodological research. The ARCAD database contains IPD from more than 38 000 patients enrolled in 46 studies and continues to collect phase III trial data. Here, we review the principal findings of the ARCAD project in respect of endpoint selection and examine their implications for cancer trials. Analysis of the database has confirmed that progression-free survival (PFS) is no longer a valid surrogate endpoint predictive of overall survival in the first-line treatment of colorectal cancer. Nonetheless, PFS remains an endpoint of choice for most first-line trials in metastatic colorectal cancer and other solid tumors. Only substantial PFS effects are likely to translate into clinically meaningful benefits, and accordingly, we advocate an oncology research model designed to identify highly effective treatments in carefully defined patient groups. We also review the use of the ARCAD database in assessing clinical response including novel response metrics and prognostic markers. These studies demonstrate the value of IPD as a tool for methodological studies and provide a reference point for the expansion of this approach within clinical cancer research.

Impact of COVID-19 pandemic restrictions on pregnancy duration and outcome in Melbourne, Australia

OBJECTIVE

To investigate the effect of restriction measures implemented to mitigate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission during the coronavirus disease 2019 (COVID-19) pandemic on pregnancy duration and outcome.

METHODS

A before-and-after study was conducted with cohort sampling in three maternity hospitals in Melbourne, Australia, including women who were pregnant when restriction measures were in place during the COVID-19 pandemic (estimated conception date between 1 November 2019 and 29 February 2020) and women who were pregnant before the restrictions (estimated conception date between 1 November 2018 and 28 February 2019). The primary outcome was delivery before 34 weeks' gestation or stillbirth. The main secondary outcome was a composite of adverse perinatal outcomes. Pregnancy outcomes were compared between women exposed to restriction measures and unexposed controls using the χ-square test and modified Poisson regression models, and duration of pregnancy was compared between the groups using survival analysis.

RESULTS

In total, 3150 women who were exposed to restriction measures during pregnancy and 3175 unexposed controls were included. Preterm birth before 34 weeks or stillbirth occurred in 95 (3.0%) exposed pregnancies and in 130 (4.1%) controls (risk ratio (RR), 0.74 (95% CI, 0.57-0.96); P = 0.021). Preterm birth before 34 weeks occurred in 2.4% of women in the exposed group and in 3.4% of women in the control group (RR, 0.71 (95% CI, 0.53-0.95); P = 0.022), without evidence of an increase in the rate of stillbirth in the exposed group (0.7% vs 0.9%; RR, 0.83 (95% CI, 0.48-1.44); P = 0.515). Competing-risks regression analysis showed that the effect of the restriction measures on spontaneous preterm birth was stronger and started earlier (subdistribution hazard ratio (HR), 0.81 (95% CI, 0.64-1.03); P = 0.087) than the effect on medically indicated preterm birth (subdistribution HR, 0.89 (95% CI, 0.70-1.12); P = 0.305). The effect was stronger in women with a previous preterm birth (RR, 0.42 (95% CI, 0.21-0.82); P = 0.008) than in parous women without a previous preterm birth (RR, 0.93 (95% CI, 0.63-1.38); P = 0.714) (P for interaction = 0.044). Composite adverse perinatal outcome was less frequent in the exposed group than in controls (all women: 2.1% vs 2.9%; RR, 0.73 (95% CI, 0.54-0.99); P = 0.042); women with a previous preterm birth: 4.5% vs 8.4%; RR, 0.54 (95% CI, 0.25-1.18); P = 0.116).

CONCLUSIONS

Restriction measures implemented to mitigate SARS-CoV-2 transmission during the COVID-19 pandemic were associated with a reduced rate of preterm birth before 34 weeks. This reduction was mainly due to a lower rate of spontaneous prematurity. The effect was more substantial in women with a previous preterm birth and was not associated with an increased stillbirth rate. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Linking Health and Housing Data to Create a Sustainable Cross-Sector Partnership

In response to the growing regional (and national) focus on health and housing intersections, two public housing authorities (PHAs) in Washington-the King County Housing Authority and the Seattle Housing Authority-joined with Public Health-Seattle & King County to form the Housing and Health (H&H) partnership in 2016. H&H linked Medicaid health claims with PHA administrative data to create a sustainable public-facing dashboard that informs health and housing stakeholders such as an Accountable Community of Health (a governing body that oversees local Medicaid transformation projects), managed care organizations, and PHAs, allowing insights into the low-income communities they serve.

Can self-regulation deliver an ethical commercial literature? A critical reading of the "Good Publication Practice" (GPP3) guidelines for industry-financed medical journal articles

Much medical journal literature is developed by the pharmaceutical and device industries, sometimes with assistance from marketing agencies, writers, and academics. This literature is vulnerable to commercial bias. The publications trade issues self-regulatory ethical guidelines for its production, called "Good Publication Practice" (GPP). I evaluated the most recent iteration, GPP3. The most progressive recommendations in GPP3 call for complete publication of all clinical trials, and full data sharing. GPP3 makes numerous further recommendations more directly concerning the publications trade. Many of these repeat existing editorial requirements, chiefly those of the International Committee of Medical Journal Editors, but readers are not adequately advised of this. Despite its emphasis on ethical and transparent reporting, the detail of GPP3 enables continued use of academic medical literature for drug marketing, on the basis of commercial steerage of content, coupled with the attribution of published articles to collaborating academic authors. As such, GPP3 provides a de facto manual for how marketing through academic journal content can be conducted in compliance with contemporary editorial standards. Consequently, the self-regulatory GPP3 guidelines are not a sound basis for the production of unbiased industry-financed medical journal literature. I suggest improvements for future iterations of these influential guidelines.

Phytosterol-based edible oleogels: A novel way of replacing saturated fat in food

This article presents a summary of recent results relating to phytosterol oleogels. Oleogels represent a novel way of replacing saturated fat in food, whilst phytosterols have been shown to actively lower low-density lipoprotein (LDL)- cholesterol levels. There are a number of technical challenges to exploiting phytosterol oleogels, including a high sensitivity to water. To facilitate their incorporation into food, the fundamental physiochemical processes which mediate the formation of these gels and two different approaches to produce phytosterol oleogels that are stable in the presence of water were explored as part of the recent Biotechnology and Biological Sciences Research Council (BBSRC)-Diet and Health Research Industry Club (DRINC)-funded Edible Oleogels for Reduction of Saturated Fat project. This report summarises the findings, which will support the development of healthier food products that are lower in saturated fat and acceptable to consumers.

Marketing trials, marketing tricks - how to spot them and how to stop them

Background

Last this year in this journal, Barbour and colleagues reported a study of “marketing trials” in leading medical journals (Trials 2016;17:31). In this commentary I discuss their research, describe new analyses of the study cohort and consider measures to address marketing within academic medical literature.

Discussion

Barbour et al. sought to identify a subgroup of “marketing trials” within leading medical journals, but in reality, nearly all industry-financed trials serve marketing functions, and many exhibit marketing-related features, including biases, in their framing, methodology or reporting. I conducted new analyses of the cohort of Barbour et al., showing that most trials funded exclusively by drug manufacturers had direct involvement of the manufacturer in design, analysis and reporting, and features supportive of product seeding. However, these commercial enterprises were without exception presented to journal readers as academic-led projects, using attributional spin, which should itself be considered an important form of marketing bias. Barbour et al. correctly conclude that commercial bias in industry clinical trials articles often requires expertise to recognize, and in many cases cannot be identified from the published journal report. Several potential remedies are discussed, including independent clinical research, data sharing, improved reporting guidance, improved tools for assessing research quality, reforms to article attribution, submission checklists and new editorial standards.

Conclusion

Medicine’s journals have a responsibility to uphold rigorous scientific and reporting standards, require ready trials data access and ensure the commercial dimensions of research are brought prominently to their readers’ attention. Failure to meet these responsibilities constitutes an enduring threat to the integrity of biomedical literature.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1827-5) contains supplementary material, which is available to authorized users.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Deconstructing the differences: a comparison of GBD 2010 and CHERG's approach to estimating the mortality burden of diarrhea, pneumonia, and their etiologies

Background

Pneumonia and diarrhea are leading causes of death for children under five (U5). It is challenging to estimate the total number of deaths and cause-specific mortality fractions. Two major efforts, one led by the Institute for Health Metrics and Evaluation (IHME) and the other led by the World Health Organization (WHO)/Child Health Epidemiology Reference Group (CHERG) created estimates for the burden of disease due to these two syndromes, yet their estimates differed greatly for 2010.

Methods

This paper discusses three main drivers of the differences: data sources, data processing, and covariates used for modelling. The paper discusses differences in the model assumptions for etiology-specific estimates and presents recommendations for improving future models.

Results

IHME’s Global Burden of Disease (GBD) 2010 study estimated 6.8 million U5 deaths compared to 7.6 million U5 deaths from CHERG. The proportional differences between the pneumonia and diarrhea burden estimates from the two groups are much larger; GBD 2010 estimated 0.847 million and CHERG estimated 1.396 million due to pneumonia. Compared to CHERG, GBD 2010 used broader inclusion criteria for verbal autopsy and vital registration data. GBD 2010 and CHERG used different data processing procedures and therefore attributed the causes of neonatal death differently. The major difference in pneumonia etiologies modeling approach was the inclusion of observational study data; GBD 2010 included observational studies. CHERG relied on vaccine efficacy studies.

Discussion

Greater transparency in modeling methods and more timely access to data sources are needed. In October 2013, the Bill & Melinda Gates Foundation (BMGF) hosted an expert meeting to examine possible approaches for better estimation. The group recommended examining the impact of data by systematically excluding sources in their models. GBD 2.0 will use a counterfactual approach for estimating mortality from pathogens due to specific etiologies to overcome bias of the methods used in GBD 2010 going forward.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0728-4) contains supplementary material, which is available to authorized users.

Integrated disease prevention campaigns: assessing country opportunity for implementation via an index approach

OBJECTIVES

To help stakeholders identify and prioritise countries with the best opportunities for implementation of an integrated prevention campaign (IPC) focused on diarrhoea, malaria and HIV prevention.

DESIGN

Cross-sectional analysis of country-specific epidemiological data using an index tool developed for this purpose.

SETTING

We calculated the total disability-adjusted life years (DALYs) attributed to diarrhoea, malaria and HIV for 214 World Bank economies. Criteria for inclusion were: low-income and middle-income countries, and total annual DALY burden in the top tertile (≥87 000 DALYs). 70 countries met inclusion criteria and were included in our opportunity analysis.

OUTCOME MEASURES

We synthesised data on 10 indicators related to the potential reduction in burden and new coverage achievable by an IPC. We scored and ranked countries based on three summary opportunity metrics: DALYs per capita across the diseases, a composite score of tertile rankings of burden for each disease, and a score combining burden and intervention opportunity.

RESULTS

We estimated the total annual global burden attributable to diarrhoea, malaria and HIV at 135 million DALYs. All of the countries with the highest opportunity for implementation of a diarrhoea, malaria and HIV IPC are in sub-Saharan Africa, regardless of opportunity metric used. Although the overall rank order changes, 16 countries rank among the top 23 highest opportunity countries for all three metrics.

CONCLUSIONS

Stakeholders can use this objective metric-based approach to prioritise countries for IPC scale-up. Priority countries are largely robust to the opportunity metric chosen.

Post-progression survival (PPS) according to treatment line, type, and time in phase III trials in advanced colorectal cancer (ACC)

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Background: Since post-progression therapy influences overall survival (OS), PPS is of interest as a determinant of OS. We quantified the relationship between several median times to event in ACC: progression-free survival (PFS), PPS and OS. We looked for factors with an impact on these times. Methods: We searched PubMed for phase III trials published between January 1998 and December 2010 in 12 leading journals. PPS is the difference between median OS and median PFS or time to tumor progression. The statistics of interest (median times [PFS, OS and PPS] and the ratio of PPS/OS) were compared using t-tests. Results: We retrieved 70 trials that yielded 71 comparisons and 156 arms (one trial was factorial) involving 38,504 patients. Trials from the period 2005-10 enrolled more patients than trials from the period 1998-2004 (medians of 246 vs 174 per arm; P=.026). PPS could be calculated for 60 trials and 135 arms (Table). Treatment type did not have an impact on any statistic. Treatment line had a significant impact on all times and on the ratio of PPS/OS, although the difference on the latter statistic was small. Treatment period had a significant impact on all times but not on the ratio of PPS/OS. Conclusions: None of the factors examined have a major impact on the ratio of PPS/OS. This suggests that in ACC, gains in PFS are translated into proportional gains in OS, one of the conditions required for PFS to be considered a surrogate for OS. [Table: see text]

How industry uses the ICMJE guidelines to manipulate authorship--and how they should be revised

Based upon his 15 years of experience as a medical writer, Alastair Matheson argues that rather than obstructing industry, the current ICMJE authorship guidelines have become its preferred tool for misattributing authorship.

Integrating biomarkers in clinical trials

Biomarkers have a growing role in clinical trials. With the advent of the targeted therapy era, molecular biomarkers in particular are becoming increasingly important within both clinical research and clinical practice. This article focuses on biomarkers that anticipate the prognosis of individual patients ('prognostic' biomarkers) and on biomarkers that predict how individual patients will respond to specific treatments ('predictive' biomarkers, also called 'effect modifiers'). Specific Phase II and III clinical trial designs are discussed in detail for their ability to validate the biomarker and/or to establish the effect of an experimental therapy in patient populations defined by the presence or absence of the biomarker. Contemporary biomarker-based clinical trials in oncology are used as examples.

Five steps for structural reform in clinical cancer research

Despite advances in the prevention and early detection of cancer and the treatment of some malignancies, clinical research has not yet delivered treatment benefits of the magnitude anticipated after the launch of imatinib, which established highly effective new treatment standards. The primary impediments to progress are scientific, but the efficiency of research is also affected by structural deficiencies relating to where and by whom it is conducted, as well as how it is organized and regulated. To optimize the research environment and maximize the benefits of improved funding, adjustments in the roles of government, industry, the academic community, national research bodies, and regulatory authorities are needed. A patchwork of reforms that are enabling in character and build on existing expertise can deliver substantial progress without the need for radical intervention.

Retrofitting houses with insulation to reduce health inequalities: aims and methods of a clustered, randomised community-based trial

This paper describes the purpose and methods of a single-blinded, clustered and randomised trial of the health impacts of insulating existing houses. The key research question was whether this intervention increased the indoor temperature and lowered the relative humidity, energy consumption and mould growth in the houses, as well as improved the health and well-being of the occupants and thereby lowered their utilisation of health care. Households in which at least one person had symptoms of respiratory disease were recruited from seven predominantly low-income communities in New Zealand. These households were then randomised within communities to receive retrofitted insulation either during or after the study. Measures at baseline (2001) and follow-up (2002) included subjective measures of health, comfort and well-being and objective measures of house condition, temperature, relative humidity, mould (speciation and mass), endotoxin, beta glucans, house dust mite allergens, general practitioner and hospital visits, and energy or fuel usage. All measurements referred to the three coldest winter months, June, July and August. From the 1352 households that were initially recruited, baseline information was obtained from 1310 households and 4413 people. At follow-up, 3312 people and 1110 households remained, an 84% household retention rate and a 75% individual retention rate. Final outcome results will be reported in a subsequent paper. The study showed that large trials of complex environmental interventions can be conducted in a robust manner with high participation rates. Critical success factors are effective community involvement and an intervention that is valued by the participants.

Back to the future: the human protein index (HPI) and the agenda for post-proteomic biology

The effort to produce an index of all human proteins (the human protein index, or HPI) began twenty years ago, before the initiation of the human genome program. Because DNA sequencing technology is inherently simpler and more scalable than protein analytical technology, and because the finiteness of genomes invited a spirit of rapid conquest, the notion of genome sequencing has displaced that of protein databases in the minds of most molecular biologists for the last decade. However, now that the human genome sequence is nearing completion, a major realignment is under way that brings proteins back to the center of biological thinking. Using an influx of new and improved protein technologies--from mass spectrometry to re-engineered two-dimensional (2-D) gel systems, the original objectives of the HPI have been expanded and the time frame for its execution radically shortened. Several additional large scale technology efforts flowing from the HPI are also described.

The effects of scopolamine and cyclizine on visual-vestibular interaction in humans

The aim of the present study was to investigate the effects of scopolamine (1.5 mg, transdermal patch) and cyclizine (50 mg tablet), at the doses usually used for the relief of motion sickness, on postural sway, optokinetic nystagmus (OKN) and circularvection (CV) in humans, using a within-subjects, double-blind, placebo-controlled design. Scopolamine and cyclizine were found to have no significant suppressive effect on these aspects of visual-vestibular interaction. Postural sway and CV were not significantly affected by either drug treatment; OKN SPV was significantly increased (p < 0.05), although OKN amplitude and frequency were unaffected. These results suggest that scopolamine and cyclizine, at doses used for the relief of motion sickness, may have minimal suppressive effects on these aspects of visual-vestibular interaction.

Back to the future: the human protein index (HPI) and the agenda for post-proteomic biology

The effort to produce an index of all human proteins (the human protein index, or HPI) began twenty years ago, before the initiation of the human genome program. Because DNA sequencing technology is inherently simpler and more scalable than protein analytical technology, and because the finiteness of genomes invited a spirit of rapid conquest, the notion of genome sequencing has displaced that of protein databases in the minds of most molecular biologists for the last decade. However, now that the human genome sequence is nearing completion, a major realignment is under way that brings proteins back to the center of biological thinking. Using an influx of new and improved protein technologies--from mass spectrometry to re-engineered two-dimensional (2-D) gel systems, the original objectives of the HPI have been expanded and the time frame for its execution radically shortened. Several additional large scale technology efforts flowing from the HPI are also described.

Demonstration of ribosomes in mesosomes associated with Bacillus subtilis protoplasts

The physiological differences between Bacillus subtilis (ATCC 6633) cells derived from a glucose-salts-yeast extract (GSY) medium and those of cells from tryptose broth permitted the identification of variables in protoplasting environments which noticeably affected the clarity of mesosomal ribosomes. They were the sucrose and magnesium ion concentrations and the type of buffer used. The environment suitable for conversion of GSY cells to the protoplast state was a 0.02 M tris(hydroxymethyl)aminomethane-hydrochloride buffer, pH 7.2, containing 0.6 M sucrose and 0.03 M MgCl(2). Branched mesosomal tubules and a unique organization of vesicles were detected in thin sections and in negative stains of the specimens. Ribosomes were demonstrable in the extruded structures associated with protoplasts that had been prepared according to four fixation schedules and embedded in either of two epoxy plastics. Adjustments in the fixation schedules improved the clarity of the large bodies of protoplast cytoplasm to a degree equivalent to that of their dangling appendages.

Influences of environmental ionic strength, pH, and magnesium ion on bactericidal and lytic activities of -lysin on Bacillus subtilis

The technique of lyophilization has been used to prepare β-lysin that can be stored in aliquots at ordinary refrigeration temperatures. It has permitted the determinations of environmental ionic strength, pH, and magnesium ion concentration favoring bactericidal and lytic activities of this agent. Killing of cells as well as lysis of protoplasts of Bacillus subtilis were favored in environments not more than 0.2 nor less than 0.15 in ionic strength. Of the environmental pH tested (6.0, 7.0, and 7.5), lysis of cells and of protoplasts was most efficient at pH 7.5, whereas bactericidal action was relatively unaffected in this range. The effectiveness of bactericidal action and of lysis of protoplasts decreased as the amount of Mg2+ in the environment increased.

Electron-dense particles resembling ribosomes in mesosomes of Bacillus subtilis

Thin-sectioning of Bacillus subtilis ATCC 6633 protoplasts and cells has revealed electron-dense particles resembling cytoplasmic ribosomes in mesosomal tubules and vesicles.

Light-induced de Novo Synthesis of Ribulose 1,5-Diphosphate Carboxylase in Greening Leaves of Barley

An antibody specific for ribulose 1,5-diphosphate carboxylase was used to isolate the enzyme from greening barley (Hordeum vulgare L.) leaves. The increase in enzymatic activity during greening was due to de novo synthesis of the enzyme. Increases in enzymatic activity were accompanied by corresponding increases in enzyme protein and by incorporation of radioactive leucine, all of which were inhibited by low concentrations of cycloheximide. (14)C-Labeled amino acids were incorporated into the enzyme by covalent peptide bonding.

A simplified purification and some properties of ribulose 1,5-diphosphate carboxylase from barley

A rapid procedure was developed for purifying ribulose 1,5-diphosphate carboxylase from barley leaves. After (NH(4))(2)SO(4) fractionation, the unique sedimentation properties of the enzyme were exploited to effect a single step purification to 90% homogeneity. High speed centrifugation pelleted the enzyme with complete recovery of activity. Residual impurities were then removed by diethylaminoethyl cellulose chromatography and density gradient centrifugation. The purified protein exhibited size heterogeneity due to polymerization. The polymerization products were enzymatically active aggregates of ribulose 1,5-diphosphate carboxylase and were precipitated by an antibody specific for the enzyme.

Effect of beta-lysin on isolated cell walls and protoplasts of Bacillus subtilis

The cytoplasmic membrane is the site of beta-lysin action. Protoplasts lysed rapidly in its presence, whereas cell walls and wall autolysis were unaffected.

Alterations in the morphology of Bacillus subtilis after exposure to beta-lysin and ultraviolet light

Viable counts, turbidities, and electron micrographs of Bacillus subtilis exposed to beta-lysin and ultraviolet light (UV), singly or in combination, were compared in an attempt to relate death with changes in morphology. The decreases in survival of both the beta-lysin- and UV-treated cells were rapid and preceded decreases in turbidity, as well as the changes in morphology. No significant differences were observed in turbidity reduction or morphological alterations of control cells from those of cells exposed to UV light. These cells developed prominent subcell wall spaces during incubation in the hypertonic stabilizing medium. No observable damage in either the cell wall or the cell membrane had taken place during 4 hr, but by 20 hr extensive damage of these two structures was apparent. The control and UV-treated cells exposed to beta-lysin did not develop prominent subcell wall spaces. Within 2 hr, lesions were observable in their cell walls, and the cytoplasmic membranes were permeable to phosphotungstic acid. The damage to these structures became more extensive with time. Although the visible changes of control and UV-treated cells were evident much later than those induced by beta-lysin, the morphological alterations in all cells were similar. It appeared that beta-lysin caused an accelerated release of an autolytic enzyme which digested the cell walls.