50 research outputs found

    Enzymatic alternatives to permanent hair straightening methods

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    Permanent hair straightening is a highly popular treatment, especially among African hair types. However, current methods rely on the use of harsh chemicals, such as sodium hydroxide or formaldehyde, and are associated with a range of health concerns, including hair breakage, loss and severe scalp disorders. Permanent hair straightening treatments usually involve a disulfide bond-breaking step which allows the opening of the hair structure, followed by mechanical hair straightening and crosslinking, which helps to set the new hair morphology. In recent years, the cosmetic sector has seen the development of a considerable range of biotechnologically-derived active agents, which offer biocompatibility, versatile activity and good performance. This project explores the feasibility of incorporating enzymes, which exhibit relevant disulfide bond-reducing and crosslinking activities in nature, into milder permanent hair straightening treatments. The thioredoxin system from Bacillus subtilis was identified as a potential alternative for breaking disulfide bonds in keratins. The enzymes thioredoxin and thioredoxin reductases were expressed and purified in E. coli. Thioredoxin activity was initially assessed on KeratecTM IFP, a solubilised wool keratin substrate bearing a mix of cystine and sulfonated thiol motifs, associated with easier enzymatic keratin penetration than insoluble counterparts. Reduced thioredoxin was regenerated either by DTT or thioredoxin reductase and NADPH, as electron donors. The reduction of S-sulfocysteine and disulfide bonds in soluble keratin by thioredoxin was observed both by Ellman’s and NADPH assays, which monitor free thiols and NADPH consumption, respectively. However, disulfide bond reducing activity was not observed using solid human hair keratin, despite attempts to improve substrate availability through treatment with keratinase from Bacillus licheniformis and swelling agents, such as urea. Enzymatic keratin crosslinking was then studied using laccase from Trametes versicolor, tyrosinase from mushroom and microbial transglutaminase, all well characterised crosslinking enzymes with activity on proteins and currently used in a range of industries (eg. food, textile). Soluble keratin crosslinking by laccase was observed using size-exclusion chromatography (SEM) and sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS PAGE), both in the presence and absence of vanillin and acetosyringone mediators. However, a lack of significant enzymatic crosslinking was noted for solid hair keratin, where no change in tensile strength was observed upon treatment with laccase. Overall, novel enzymatic reducing and crosslinking modifications were successfully carried out on solubilised keratin. However, challenges remain regarding solid hair keratin, associated with poor substrate availability and enzyme penetration

    Enzymatic alternatives to permanent hair straightening methods

    Get PDF
    Permanent hair straightening is a highly popular treatment, especially among African hair types. However, current methods rely on the use of harsh chemicals, such as sodium hydroxide or formaldehyde, and are associated with a range of health concerns, including hair breakage, loss and severe scalp disorders. Permanent hair straightening treatments usually involve a disulfide bond-breaking step which allows the opening of the hair structure, followed by mechanical hair straightening and crosslinking, which helps to set the new hair morphology. In recent years, the cosmetic sector has seen the development of a considerable range of biotechnologically-derived active agents, which offer biocompatibility, versatile activity and good performance. This project explores the feasibility of incorporating enzymes, which exhibit relevant disulfide bond-reducing and crosslinking activities in nature, into milder permanent hair straightening treatments. The thioredoxin system from Bacillus subtilis was identified as a potential alternative for breaking disulfide bonds in keratins. The enzymes thioredoxin and thioredoxin reductases were expressed and purified in E. coli. Thioredoxin activity was initially assessed on KeratecTM IFP, a solubilised wool keratin substrate bearing a mix of cystine and sulfonated thiol motifs, associated with easier enzymatic keratin penetration than insoluble counterparts. Reduced thioredoxin was regenerated either by DTT or thioredoxin reductase and NADPH, as electron donors. The reduction of S-sulfocysteine and disulfide bonds in soluble keratin by thioredoxin was observed both by Ellman’s and NADPH assays, which monitor free thiols and NADPH consumption, respectively. However, disulfide bond reducing activity was not observed using solid human hair keratin, despite attempts to improve substrate availability through treatment with keratinase from Bacillus licheniformis and swelling agents, such as urea. Enzymatic keratin crosslinking was then studied using laccase from Trametes versicolor, tyrosinase from mushroom and microbial transglutaminase, all well characterised crosslinking enzymes with activity on proteins and currently used in a range of industries (eg. food, textile). Soluble keratin crosslinking by laccase was observed using size-exclusion chromatography (SEM) and sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS PAGE), both in the presence and absence of vanillin and acetosyringone mediators. However, a lack of significant enzymatic crosslinking was noted for solid hair keratin, where no change in tensile strength was observed upon treatment with laccase. Overall, novel enzymatic reducing and crosslinking modifications were successfully carried out on solubilised keratin. However, challenges remain regarding solid hair keratin, associated with poor substrate availability and enzyme penetration

    Compound-specific radiocarbon, stable carbon isotope and biomarker analysis of mixed marine/terrestrial lipids preserved in archaeological pottery vessels.

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    At archaeological sites located on islands or near the coast, the potential exists for lipid extracts of potsherds to contain fatty acids (FA) from both aquatic and terrestrial organisms, meaning that consideration must be given to marine reservoir effects (MRE) in radiocarbon (14C) analyses. Here we studied the site of Bornais (Outer Hebrides, UK) where a local MRE, ΔR of –65 ± 45 yr was determined through the paired 14C determinations of terrestrial and marine faunal bones. Lipid analysis of 49 potsherds, revealed aquatic biomarkers in 45% of the vessels, and δ13C values of C16:0 and C18:0 FAs revealed ruminant and marine product mixing for 71% of the vessels. Compound-specific 14C analysis (CSRA) of FAs yielded intermediate 14C ages between those of terrestrial and marine bones from the same contexts, confirming an MRE existed. A database containing δ13C values for FAs from reference terrestrial and marine organisms provided endmembers for calculating the percentage marine-derived C (%marine) in FAs. We show that lipid 14C dates can be corrected using determined %marine and ΔR values, such that pottery vessels from coastal locations can be 14C dated by CSRA of FAs

    Coronavirus host genetics South Africa (COHG-SA) database—a variant database for gene regions associated with SARS-CoV-2 outcomes

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    The SARS-CoV-2 virus is responsible for the COVID-19 global public health emergency, and the disease it causes is highly variable in its clinical presentation. Clinical phenotypes are heterogeneous both in terms of presentation of symptoms in the host and response to therapy. Several studies and initiatives have been established to analyse and review host genetic epidemiology associated with COVID-19. Our research group curated these articles into a web-based database using the python applicationserver framework Django. The database provides a searchable research tool describing current literature surrounding COVID-19 host genetic factors associated with disease outcome. This paper describes the COHG-SA database and provides an overview of the analyses that can be derived from these data.The South African Medical Research Council through its Division of Research Capacity Development under the SAMRC Internship Scholarship Programme from funding received from the South African National Treasury; the CIDRI-Africa Wellcome Trust grant; the NIH H3ABioNET award; the UKRI/MRC and the University of Pretoria through the Institute for Cellular and Molecular Medicine.https://www.nature.com/ejhgam2023BiochemistryGeneticsImmunologyMicrobiology and Plant Patholog

    Distinguishing the Impacts of Inadequate Prey and Vessel Traffic on an Endangered Killer Whale (Orcinus orca) Population

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    Managing endangered species often involves evaluating the relative impacts of multiple anthropogenic and ecological pressures. This challenge is particularly formidable for cetaceans, which spend the majority of their time underwater. Noninvasive physiological approaches can be especially informative in this regard. We used a combination of fecal thyroid (T3) and glucocorticoid (GC) hormone measures to assess two threats influencing the endangered southern resident killer whales (SRKW; Orcinus orca) that frequent the inland waters of British Columbia, Canada and Washington, U.S.A. Glucocorticoids increase in response to nutritional and psychological stress, whereas thyroid hormone declines in response to nutritional stress but is unaffected by psychological stress. The inadequate prey hypothesis argues that the killer whales have become prey limited due to reductions of their dominant prey, Chinook salmon (Oncorhynchus tshawytscha). The vessel impact hypothesis argues that high numbers of vessels in close proximity to the whales cause disturbance via psychological stress and/or impaired foraging ability. The GC and T3 measures supported the inadequate prey hypothesis. In particular, GC concentrations were negatively correlated with short-term changes in prey availability. Whereas, T3 concentrations varied by date and year in a manner that corresponded with more long-term prey availability. Physiological correlations with prey overshadowed any impacts of vessels since GCs were lowest during the peak in vessel abundance, which also coincided with the peak in salmon availability. Our results suggest that identification and recovery of strategic salmon populations in the SRKW diet are important to effectively promote SRKW recovery

    Reporting Methods of Blinding in Randomized Trials Assessing Nonpharmacological Treatments

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    BACKGROUND: Blinding is a cornerstone of treatment evaluation. Blinding is more difficult to obtain in trials assessing nonpharmacological treatment and frequently relies on “creative” (nonstandard) methods. The purpose of this study was to systematically describe the strategies used to obtain blinding in a sample of randomized controlled trials of nonpharmacological treatment. METHODS AND FINDINGS: We systematically searched in Medline and the Cochrane Methodology Register for randomized controlled trials (RCTs) assessing nonpharmacological treatment with blinding, published during 2004 in high-impact-factor journals. Data were extracted using a standardized extraction form. We identified 145 articles, with the method of blinding described in 123 of the reports. Methods of blinding of participants and/or health care providers and/or other caregivers concerned mainly use of sham procedures such as simulation of surgical procedures, similar attention-control interventions, or a placebo with a different mode of administration for rehabilitation or psychotherapy. Trials assessing devices reported various placebo interventions such as use of sham prosthesis, identical apparatus (e.g., identical but inactivated machine or use of activated machine with a barrier to block the treatment), or simulation of using a device. Blinding participants to the study hypothesis was also an important method of blinding. The methods reported for blinding outcome assessors relied mainly on centralized assessment of paraclinical examinations, clinical examinations (i.e., use of video, audiotape, photography), or adjudications of clinical events. CONCLUSIONS: This study classifies blinding methods and provides a detailed description of methods that could overcome some barriers of blinding in clinical trials assessing nonpharmacological treatment, and provides information for readers assessing the quality of results of such trials

    Dolutegravir twice-daily dosing in children with HIV-associated tuberculosis: a pharmacokinetic and safety study within the open-label, multicentre, randomised, non-inferiority ODYSSEY trial

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    Background: Children with HIV-associated tuberculosis (TB) have few antiretroviral therapy (ART) options. We aimed to evaluate the safety and pharmacokinetics of dolutegravir twice-daily dosing in children receiving rifampicin for HIV-associated TB. Methods: We nested a two-period, fixed-order pharmacokinetic substudy within the open-label, multicentre, randomised, controlled, non-inferiority ODYSSEY trial at research centres in South Africa, Uganda, and Zimbabwe. Children (aged 4 weeks to <18 years) with HIV-associated TB who were receiving rifampicin and twice-daily dolutegravir were eligible for inclusion. We did a 12-h pharmacokinetic profile on rifampicin and twice-daily dolutegravir and a 24-h profile on once-daily dolutegravir. Geometric mean ratios for trough plasma concentration (Ctrough), area under the plasma concentration time curve from 0 h to 24 h after dosing (AUC0–24 h), and maximum plasma concentration (Cmax) were used to compare dolutegravir concentrations between substudy days. We assessed rifampicin Cmax on the first substudy day. All children within ODYSSEY with HIV-associated TB who received rifampicin and twice-daily dolutegravir were included in the safety analysis. We described adverse events reported from starting twice-daily dolutegravir to 30 days after returning to once-daily dolutegravir. This trial is registered with ClinicalTrials.gov (NCT02259127), EudraCT (2014–002632-14), and the ISRCTN registry (ISRCTN91737921). Findings: Between Sept 20, 2016, and June 28, 2021, 37 children with HIV-associated TB (median age 11·9 years [range 0·4–17·6], 19 [51%] were female and 18 [49%] were male, 36 [97%] in Africa and one [3%] in Thailand) received rifampicin with twice-daily dolutegravir and were included in the safety analysis. 20 (54%) of 37 children enrolled in the pharmacokinetic substudy, 14 of whom contributed at least one evaluable pharmacokinetic curve for dolutegravir, including 12 who had within-participant comparisons. Geometric mean ratios for rifampicin and twice-daily dolutegravir versus once-daily dolutegravir were 1·51 (90% CI 1·08–2·11) for Ctrough, 1·23 (0·99–1·53) for AUC0–24 h, and 0·94 (0·76–1·16) for Cmax. Individual dolutegravir Ctrough concentrations were higher than the 90% effective concentration (ie, 0·32 mg/L) in all children receiving rifampicin and twice-daily dolutegravir. Of 18 children with evaluable rifampicin concentrations, 15 (83%) had a Cmax of less than the optimal target concentration of 8 mg/L. Rifampicin geometric mean Cmax was 5·1 mg/L (coefficient of variation 71%). During a median follow-up of 31 weeks (IQR 30–40), 15 grade 3 or higher adverse events occurred among 11 (30%) of 37 children, ten serious adverse events occurred among eight (22%) children, including two deaths (one tuberculosis-related death, one death due to traumatic injury); no adverse events, including deaths, were considered related to dolutegravir. Interpretation: Twice-daily dolutegravir was shown to be safe and sufficient to overcome the rifampicin enzyme-inducing effect in children, and could provide a practical ART option for children with HIV-associated TB

    Neuropsychiatric manifestations and sleep disturbances with dolutegravir-based antiretroviral therapy versus standard of care in children and adolescents: a secondary analysis of the ODYSSEY trial

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    BACKGROUND: Cohort studies in adults with HIV showed that dolutegravir was associated with neuropsychiatric adverse events and sleep problems, yet data are scarce in children and adolescents. We aimed to evaluate neuropsychiatric manifestations in children and adolescents treated with dolutegravir-based treatment versus alternative antiretroviral therapy. METHODS: This is a secondary analysis of ODYSSEY, an open-label, multicentre, randomised, non-inferiority trial, in which adolescents and children initiating first-line or second-line antiretroviral therapy were randomly assigned 1:1 to dolutegravir-based treatment or standard-of-care treatment. We assessed neuropsychiatric adverse events (reported by clinicians) and responses to the mood and sleep questionnaires (reported by the participant or their carer) in both groups. We compared the proportions of patients with neuropsychiatric adverse events (neurological, psychiatric, and total), time to first neuropsychiatric adverse event, and participant-reported responses to questionnaires capturing issues with mood, suicidal thoughts, and sleep problems. FINDINGS: Between Sept 20, 2016, and June 22, 2018, 707 participants were enrolled, of whom 345 (49%) were female and 362 (51%) were male, and 623 (88%) were Black-African. Of 707 participants, 350 (50%) were randomly assigned to dolutegravir-based antiretroviral therapy and 357 (50%) to non-dolutegravir-based standard-of-care. 311 (44%) of 707 participants started first-line antiretroviral therapy (ODYSSEY-A; 145 [92%] of 157 participants had efavirenz-based therapy in the standard-of-care group), and 396 (56%) of 707 started second-line therapy (ODYSSEY-B; 195 [98%] of 200 had protease inhibitor-based therapy in the standard-of-care group). During follow-up (median 142 weeks, IQR 124–159), 23 participants had 31 neuropsychiatric adverse events (15 in the dolutegravir group and eight in the standard-of-care group; difference in proportion of participants with ≥1 event p=0·13). 11 participants had one or more neurological events (six and five; p=0·74) and 14 participants had one or more psychiatric events (ten and four; p=0·097). Among 14 participants with psychiatric events, eight participants in the dolutegravir group and four in standard-of-care group had suicidal ideation or behaviour. More participants in the dolutegravir group than the standard-of-care group reported symptoms of self-harm (eight vs one; p=0·025), life not worth living (17 vs five; p=0·0091), or suicidal thoughts (13 vs none; p=0·0006) at one or more follow-up visits. Most reports were transient. There were no differences by treatment group in low mood or feeling sad, problems concentrating, feeling worried or feeling angry or aggressive, sleep problems, or sleep quality. INTERPRETATION: The numbers of neuropsychiatric adverse events and reported neuropsychiatric symptoms were low. However, numerically more participants had psychiatric events and reported suicidality ideation in the dolutegravir group than the standard-of-care group. These differences should be interpreted with caution in an open-label trial. Clinicians and policy makers should consider including suicidality screening of children or adolescents receiving dolutegravir

    In silico toxicology protocols

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    The present publication surveys several applications of in silico (i.e., computational) toxicology approaches across different industries and institutions. It highlights the need to develop standardized protocols when conducting toxicity-related predictions. This contribution articulates the information needed for protocols to support in silico predictions for major toxicological endpoints of concern (e.g., genetic toxicity, carcinogenicity, acute toxicity, reproductive toxicity, developmental toxicity) across several industries and regulatory bodies. Such novel in silico toxicology (IST) protocols, when fully developed and implemented, will ensure in silico toxicological assessments are performed and evaluated in a consistent, reproducible, and well-documented manner across industries and regulatory bodies to support wider uptake and acceptance of the approaches. The development of IST protocols is an initiative developed through a collaboration among an international consortium to reflect the state-of-the-art in in silico toxicology for hazard identification and characterization. A general outline for describing the development of such protocols is included and it is based on in silico predictions and/or available experimental data for a defined series of relevant toxicological effects or mechanisms. The publication presents a novel approach for determining the reliability of in silico predictions alongside experimental data. In addition, we discuss how to determine the level of confidence in the assessment based on the relevance and reliability of the information
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