RESUMO
The World Health Organization roadmap for neglected tropical diseases (NTDs) sets out ambitious targets for disease control and elimination by 2030, including 90% fewer people requiring interventions against NTDs and the elimination of at least 1 NTD in 100 countries. Mathematical models are an important tool for understanding NTD dynamics, optimizing interventions, assessing the efficacy of new tools, and estimating the economic costs associated with control programs. As NTD control shifts to increased country ownership and programs progress toward disease elimination, tailored models that better incorporate local context and can help to address questions that are important for decision-making at the national level are gaining importance. In this introduction to the supplement, New Tools and Nuanced Interventions to Accelerate Achievement of the 2030 Roadmap for Neglected Tropical Diseases, we discuss current challenges in generating more locally relevant models and summarize how the articles in this supplement present novel ways in which NTD modeling can help to accelerate achievement and sustainability of the 2030 targets.
Assuntos
Doenças Negligenciadas , Medicina Tropical , Organização Mundial da Saúde , Doenças Negligenciadas/prevenção & controle , Humanos , Erradicação de Doenças/métodos , Saúde Global , Controle de Doenças Transmissíveis/métodos , Modelos TeóricosRESUMO
Over the past decade, considerable progress has been made in the control, elimination, and eradication of neglected tropical diseases (NTDs). Despite these advances, most NTD programs have recently experienced important setbacks; for example, NTD interventions were some of the most frequently and severely impacted by service disruptions due to the coronavirus disease 2019 (COVID-19) pandemic. Mathematical modeling can help inform selection of interventions to meet the targets set out in the NTD road map 2021-2030, and such studies should prioritize questions that are relevant for decision-makers, especially those designing, implementing, and evaluating national and subnational programs. In September 2022, the World Health Organization hosted a stakeholder meeting to identify such priority modeling questions across a range of NTDs and to consider how modeling could inform local decision making. Here, we summarize the outputs of the meeting, highlight common themes in the questions being asked, and discuss how quantitative modeling can support programmatic decisions that may accelerate progress towards the 2030 targets.
Assuntos
COVID-19 , Doenças Negligenciadas , Medicina Tropical , Doenças Negligenciadas/prevenção & controle , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , Modelos Teóricos , Organização Mundial da Saúde , SARS-CoV-2 , Tomada de Decisões , Saúde GlobalRESUMO
Assessing the feasibility of 2030 as a target date for global elimination of trachoma, and identification of districts that may require enhanced treatment to meet World Health Organization (WHO) elimination criteria by this date are key challenges in operational planning for trachoma programmes. Here we address these challenges by prospectively evaluating forecasting models of trachomatous inflammation-follicular (TF) prevalence, leveraging ensemble-based approaches. Seven candidate probabilistic models were developed to forecast district-wise TF prevalence in 11 760 districts, trained using district-level data on the population prevalence of TF in children aged 1-9 years from 2004 to 2022. Geographical location, history of mass drug administration treatment, and previously measured prevalence data were included in these models as key predictors. The best-performing models were included in an ensemble, using weights derived from their relative likelihood scores. To incorporate the inherent stochasticity of disease transmission and challenges of population-level surveillance, we forecasted probability distributions for the TF prevalence in each geographic district, rather than predicting a single value. Based on our probabilistic forecasts, 1.46% (95% confidence interval [CI]: 1.43-1.48%) of all districts in trachoma-endemic countries, equivalent to 172 districts, will exceed the 5% TF control threshold in 2030 with the current interventions. Global elimination of trachoma as a public health problem by 2030 may require enhanced intervention and/or surveillance of high-risk districts.
Assuntos
Erradicação de Doenças , Previsões , Saúde Pública , Tracoma , Tracoma/epidemiologia , Tracoma/prevenção & controle , Humanos , Pré-Escolar , Lactente , Criança , Erradicação de Doenças/métodos , Prevalência , Modelos Estatísticos , Administração Massiva de Medicamentos , Organização Mundial da Saúde , Saúde Global , Masculino , FemininoRESUMO
BACKGROUND: WHO has proposed elimination of transmission of onchocerciasis (river blindness) by 2030. More than 99% of cases of onchocerciasis are in sub-Saharan Africa. Vector control and mass drug administration of ivermectin have been the main interventions for many years, with varying success. We aimed to identify factors associated with elimination of onchocerciasis transmission in sub-Saharan Africa. METHODS: For this systematic review and meta-analysis we searched for published articles reporting epidemiological or entomological assessments of onchocerciasis transmission status in sub-Saharan Africa, with or without vector control. We searched MEDLINE, PubMed, Web of Science, Embase, Cochrane Central Register of Controlled Trials, African Index Medicus, and Google Scholar databases for all articles published from database inception to Aug 19, 2023, without language restrictions. The search terms used were "onchocerciasis" AND "ivermectin" AND "mass drug administration". The three inclusion criteria were (1) focus or foci located in Africa, (2) reporting of elimination of transmission or at least 10 years of ivermectin mass drug administration in the focus or foci, and (3) inclusion of at least one of the following assessments: microfilarial prevalence, nodule prevalence, Ov16 antibody seroprevalence, and blackfly infectivity prevalence. Epidemiological modelling studies and reviews were excluded. Four reviewers (NM, AJ, AM, and TNK) extracted data in duplicate from the full-text articles using a data extraction tool developed in Excel with columns recording the data of interest to be extracted, and a column where important comments for each study could be highlighted. We did not request any individual-level data from authors. Foci were classified as achieving elimination of transmission, being close to elimination of transmission, or with ongoing transmission. We used mixed-effects meta-regression models to identify factors associated with transmission status. This study is registered in PROSPERO, CRD42022338986. FINDINGS: Of 1525 articles screened after the removal of duplicates, 75 provided 282 records from 238 distinct foci in 19 (70%) of the 27 onchocerciasis-endemic countries in sub-Saharan Africa. Elimination of transmission was reported in 24 (9%) records, being close to elimination of transmission in 86 (30%) records, and ongoing transmission in 172 (61%) records. I2 was 83·3% (95% CI 79·7 to 86·3). Records reporting 10 or more years of continuous mass drug administration with 80% or more therapeutic coverage of the eligible population yielded significantly higher odds of achieving elimination of transmission (log-odds 8·5 [95% CI 3·5 to 13·5]) or elimination and being close to elimination of transmission (42·4 [18·7 to 66·1]) than those with no years achieving 80% coverage or more. Reporting 15-19 years of ivermectin mass drug administration (22·7 [17·2 to 28·2]) and biannual treatment (43·3 [27·2 to 59·3]) were positively associated with elimination and being close to elimination of transmission compared with less than 15 years and no biannual mass drug administration, respectively. Having had vector control without vector elimination (-42·8 [-59·1 to -26·5]) and baseline holoendemicity (-41·97 [-60·6 to -23·2]) were associated with increased risk of ongoing transmission compared with no vector control and hypoendemicity, respectively. Blackfly disappearance due to vector control or environmental change contributed to elimination of transmission. INTERPRETATION: Mass drug administration duration, frequency, and coverage; baseline endemicity; and vector elimination or disappearance are important determinants of elimination of onchocerciasis transmission in sub-Saharan Africa. Our findings underscore the importance of improving and sustaining high therapeutic coverage and increasing treatment frequency if countries are to achieve elimination of onchocerciasis transmission. FUNDING: The Bill & Melinda Gates Foundation and Neglected Tropical Diseases Modelling Consortium, UK Medical Research Council, and Global Health EDCTP3 Joint Undertaking. TRANSLATIONS: For the Swahili, French, Spanish and Portuguese translations of the abstract see Supplementary Materials section.
Assuntos
Ivermectina , Administração Massiva de Medicamentos , Oncocercose Ocular , Ivermectina/administração & dosagem , Ivermectina/uso terapêutico , Humanos , África Subsaariana/epidemiologia , Oncocercose Ocular/epidemiologia , Oncocercose Ocular/prevenção & controle , Oncocercose Ocular/tratamento farmacológico , Animais , Oncocercose/epidemiologia , Oncocercose/transmissão , Oncocercose/prevenção & controle , Oncocercose/tratamento farmacológico , Erradicação de Doenças , Controle de Insetos/métodos , Antiparasitários/administração & dosagem , Antiparasitários/uso terapêuticoRESUMO
Due to the COVID-19 pandemic, many key neglected tropical disease (NTD) activities have been postponed. This hindrance comes at a time when the NTDs are progressing towards their ambitious goals for 2030. Mathematical modelling on several NTDs, namely gambiense sleeping sickness, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiases (STH), trachoma, and visceral leishmaniasis, shows that the impact of this disruption will vary across the diseases. Programs face a risk of resurgence, which will be fastest in high-transmission areas. Furthermore, of the mass drug administration diseases, schistosomiasis, STH, and trachoma are likely to encounter faster resurgence. The case-finding diseases (gambiense sleeping sickness and visceral leishmaniasis) are likely to have fewer cases being detected but may face an increasing underlying rate of new infections. However, once programs are able to resume, there are ways to mitigate the impact and accelerate progress towards the 2030 goals.
Assuntos
COVID-19 , Medicina Tropical , Humanos , Doenças Negligenciadas/epidemiologia , Pandemias , SARS-CoV-2RESUMO
Objetivo: Evidenciar, por meio de revisão de literatura, a importância do envolvimento paterno no decorrer do ciclo gravídico-puerperal, no favorecimento do trinômio mãe-pai-filho. Método: Trata-se de revisão integrativa da literatura, realizada em outubro de 2020, nas bases de dados Biblioteca Virtual em Saúde, Portal de Periódicos Capes e o Scielo, com recorte temporal de 20 anos em que 24 artigos foram analisados. Resultados: Observou-se predomínio de estudos com abordagem qualitativa (n=24) 100%, em periódicos nacionais (n=23) 95,83%, seu nível de evidência muito baixo, segundo método Grade (n=24) 100%, se concentraram em periódicos da área de enfermagem (n=16) 66,66% e na base de dados BVS (n=21) 87,50%. Conclusão: A inclusão durante as consultas de pré-natal, além de promover da saúde, previne e facilita diagnósticos de enfermidades e fortalecimento de vínculos que, por sua vez, possibilitam um melhor desenvolvimento fetal e um acompanhamento de saúde do casal durante todo o ciclo gravídico-puerperal, a partir da inserção precoce dos pais no trinômio mãe-pai-filho.
Objective: to highlight, through a literature review, the importance of paternal involvement during the pregnancy-puerperal cycle, in favor of the mother-father-son trinomial. Method: This is an integrative literature review conducted in October 2020 in the databases Virtual Library in Health, Portal de Periódicos Capes and Scielo with a 20-year time frame in which 24 articles were analyzed. Results: There was a predominance of studies with a qualitative approach (n = 24) 100%, in national journals (n = 23) 95.83%, their level of evidence very low according to the Grade method (n = 24) 100%, if concentrated in nursing journals (n = 16) 66.66% and in the VHL database (n = 21) 87.50%. Conclusion: inclusion during prenatal consultations, in addition to promoting health, prevents and facilitates diagnoses of illnesses and strengthens bonds, which, in turn, enable better fetal development and health monitoring of the couple throughout the pregnancy cycle -puerperal, from the early insertion of parents in the motherfather-son trinomial.
Objetivo: Resaltar, a través de una revisión de la literatura, la importancia del involucramiento paterno durante el ciclo embarazo-puerperal, en favor del trinomio Madre-Padre-Hijo. Método: Se trata de una revisión integradora de la literatura, realizada en octubre de 2020, en las bases de datos Biblioteca Virtual en Salud, Portal de Periódicos Capes y Scielo, con un plazo de 20 años en el que se analizaron 24 artículos. Resultados: Predominó los estudios con enfoque cualitativo (n = 24) 100%, en revistas nacionales (n = 23) 95,83%, su nivel de evidencia muy bajo, según el método Grade (n = 24) 100%, si concentrado en revistas de enfermería (n = 16) 66,66% y en la base de datos BVS (n = 21) 87,50%. Conclusión: La inclusión durante las consultas prenatales, además de promover la salud, previene y facilita el diagnóstico de enfermedades y fortalece lazos que, a su vez, permiten un mejor desarrollo fetal y seguimiento de la salud de la pareja durante todo el ciclo del embarazo -puerperal, desde la inserción temprana de los padres en el trinomio madre-padre-hijo.
Assuntos
Cuidado Pré-Natal , Parto Humanizado , Relações Pai-FilhoRESUMO
As neglected tropical disease programs look to consolidate the successes of moving towards elimination, we need to understand the dynamics of transmission at low prevalence to inform surveillance strategies for detecting elimination and resurgence. In this special collection, modelling insights are used to highlight drivers of local elimination, evaluate strategies for detecting resurgence, and show the importance of rational spatial sampling schemes for several neglected tropical diseases (specifically schistosomiasis, soil-transmitted helminths, lymphatic filariasis, trachoma, onchocerciasis, visceral leishmaniasis, and gambiense sleeping sickness).
Assuntos
Erradicação de Doenças/estatística & dados numéricos , Doenças Negligenciadas/diagnóstico , Vigilância da População/métodos , Medicina Tropical , HumanosRESUMO
Silk fibroin demonstrates great biocompatibility and is suitable for many biomedical applications, including tissue engineering and regenerative medicine. Current research focuses on manipulating the physico-chemical properties of fibroin, and examining the effect of this manipulation on firobin's biocompatibility. Regenerated silk fibroin was modified by in vitro enzymatic phosphorylation and cast into films. Films were produced by blending, at several ratios, the phosphorylated and un-phosphorylated fibroin solutions. Fourier transform infra-red spectroscopy was used to determine the specific P-OH vibration peak, confirming the phosphorylation of the regenerated silk fibroin solution. Differential scanning calorimetry showed that phosphorylation altered the intra- and inter-molecular interactions. Further experiments demonstrated that phosphorylation can be used to tailor the hydrophylicity/hydrophobicity ratio as well as the crystalinity of silk fibroin films. Release profiling of a model drug was highly dependent on silk modification level. Cytotoxicity assays showed that exposure to lixiviates of phosphorylated films only slightly affected cellular metabolism and proliferation, although direct contact resulted in a strong direct correlation between phosphorylation level and cell proliferation. This new method for tuning silk biomaterials to obtain specific structural and biochemical features can be adapted for a wide range of applications. Phosphorylation of silk fibroins may be applied to improve the cytocompatibility of any silk-based device that is considered to be in contact with live animals or human tissues.
Assuntos
Materiais Biocompatíveis/química , Biotecnologia/métodos , Fibroínas/química , Fosfoproteínas/química , Animais , Materiais Biocompatíveis/metabolismo , Linhagem Celular , Fibroínas/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Metanol , Camundongos , Modelos Químicos , Fosfoproteínas/metabolismo , Fosforilação , Piroxicam/química , Piroxicam/farmacocinética , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Keratins are naturally derived proteins that can be fabricated into several biomaterials morphologies including films, sponges and hydrogels. As a physical matrix, keratin biomaterials have several advantages of both natural and synthetic materials that are useful in tissue engineering and controlled released applications. Like other naturally derived protein biomaterials, such as collagen, keratin possess amino acid sequences, similar to the ones found on extracellular matrix (ECM), that may interact with integrins showing their ability to support cellular attachment, proliferation and migration. The ability of developing biomaterials that mimic ECM has the potential to control several biological processes and this is the case for keratin which has been used in a variety of biomedical applications due to its biocompatibility and biodegradability. This review describes the progress to date towards the use of keratin in the field of wound healing, tissue engineering and drug delivery applications, with highlight to reports of particular relevance to the development of the underlying biomaterials science in this area.
Assuntos
Materiais Biocompatíveis , Curativos Biológicos , Portadores de Fármacos , Queratinas/química , Queratinas/uso terapêutico , Tecnologia Farmacêutica/métodos , Engenharia Tecidual/métodos , Alicerces Teciduais , Cicatrização , Animais , Transplante de Células , Química Farmacêutica , HumanosRESUMO
Silk fibroin (SF) and elastin (EL) scaffolds were successfully produced for the first time for the treatment of burn wounds. The self-assembly properties of SF, together with the excellent chemical and mechanical stability and biocompatibility, were combined with elastin protein to produce scaffolds with the ability to mimic the extracellular matrix (ECM). Porous scaffolds were obtained by lyophilization and were further crosslinked with genipin (GE). Genipin crosslinking induces the conformational transition from random coil to ß-sheet of SF chains, yielding scaffolds with smaller pore size and reduced swelling ratios, degradation and release rates. All results indicated that the composition of the scaffolds had a significant effect on their physical properties, and that can easily be tuned to obtain scaffolds suitable for biological applications. Wound healing was assessed through the use of human full-thickness skin equivalents (EpidermFT). Standardized burn wounds were induced by a cautery and the best re-epithelialization and the fastest wound closure was obtained in wounds treated with 50SF scaffolds; these contain the highest amount of elastin after 6 days of healing in comparison with other dressings and controls. The cytocompatibility demonstrated with human skin fibroblasts together with the healing improvement make these SF/EL scaffolds suitable for wound dressing applications.
Assuntos
Bandagens , Elastina/farmacologia , Fibroínas/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Bombyx , Queimaduras/patologia , Varredura Diferencial de Calorimetria , Bovinos , Morte Celular/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Reagentes de Ligações Cruzadas/farmacologia , Meios de Cultivo Condicionados/farmacologia , DNA/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/patologia , Gentamicinas/farmacologia , Humanos , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Cinética , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Sus scrofa , Alicerces Teciduais/químicaRESUMO
In this work, we report a novel approach using proteinaceous microspheres of bovine serum albumin (BSA), human serum albumin (HSA) and silk fibroin (SF) containing different organic solvents, namely n-dodecane, mineral oil and vegetable oil, to reduce the activity of human neutrophil elastase (HNE) found in high levels on chronic wounds. The ability of these devices to inhibit HNE was evaluated using porcine pancreatic elastase (PPE) solution as a model of wound exudates. The results obtained indicated that the level of PPE activity can be tuned by changing the organic solvent present on different protein microspheres, thus showing an innovative way of controlling the elastase-antielastase imbalance found in chronic wounds. Furthermore, these proteinaceous microspheres were shown to be important carriers of elastase inhibitors causing no cytotoxicity in human skin fibroblasts in vitro, making them suitable for biomedical applications, such as chronic wounds.
Assuntos
Sistemas de Liberação de Medicamentos/métodos , Fibroínas/farmacologia , Microesferas , Albumina Sérica/farmacologia , Cicatrização/efeitos dos fármacos , Alcanos/química , Alcanos/farmacologia , Análise de Variância , Animais , Bovinos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Fibroblastos , Fibroínas/química , Humanos , Elastase de Leucócito/antagonistas & inibidores , Óleo Mineral/química , Óleo Mineral/farmacologia , Elastase Pancreática/antagonistas & inibidores , Óleos de Plantas/química , Óleos de Plantas/farmacologia , Albumina Sérica/química , Suínos , UltrassomRESUMO
Chronic wounds are the result of excessive amounts of tissue destructive proteases such as human neutrophil elastase (HNE). The high levels of this enzyme found on those types of wounds inactivate the endogenous inhibitor barrier thus, the search for new HNE inhibitors is required. This work presents two new HNE inhibitor peptides, which were synthesized based on the reactive-site loop of the Bowman-Birk inhibitor protein. The results obtained indicated that these new peptides are competitive inhibitors for HNE and, the inhibitory activity can be modulated by modifications introduced at the N- and C-terminal of the peptides. Furthermore, these peptides were also able to inhibit elastase from a human wound exudate while showing no cytotoxicity against human skin fibroblasts in vitro, greatly supporting their potential application in chronic wound treatment.
Assuntos
Elastase de Leucócito/antagonistas & inibidores , Peptídeos/farmacologia , Proteínas Secretadas Inibidoras de Proteinases/farmacologia , Sequência de Aminoácidos , Animais , Domínio Catalítico , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroínas/metabolismo , Humanos , Concentração Inibidora 50 , Cinética , Elastase de Leucócito/química , Elastase de Leucócito/metabolismo , Teste de Materiais , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/metabolismo , Peptídeos/toxicidade , Proteínas Secretadas Inibidoras de Proteinases/química , Proteínas Secretadas Inibidoras de Proteinases/metabolismo , Proteínas Secretadas Inibidoras de Proteinases/toxicidade , Especificidade por Substrato , Inibidor da Tripsina de Soja de Bowman-Birk/químicaRESUMO
In living systems, protein disulphide isomerase (PDI, EC 5.3.4.1) regulates the formation of new disulphide bonds in proteins (oxidase activity) and catalyzes the rearrangement of non-native disulphide bonds (isomerase activity), leading proteins towards their native configuration. In this study, PDI was used to attach cysteine-containing compounds (CCCs) onto hair, to enhance compound migration within hair fibre and to trigger protein release. A fluorescent (5(6)-TAMRA)-labelled keratin peptide was incorporated into hair by using PDI. Similarly, PDI promoted the grafting of a cysteine-functionalized dye onto wool, as suggested by matrix-assisted laser desorption and ionization time-of-flight results. These reactions were thought to involve oxidation of disulphide bonds between CCCs and wool or hair cysteine residues, catalyzed by the oxidized PDI active site. On the other hand, PDI was demonstrated to enhance the migration of a disulphide bond-functionalized dye within the keratin matrix and trigger the release of RNase A from wool fibres' surface. These observations may indicate that an isomerisation reaction occurred, catalyzed by the reduced PDI active site, to achieve the thiol-disulphide exchange, i.e. the rearrangement of disulphide bonds between CCCs and keratin. The present communication aims to highlight promising biotechnological applications of PDI, derived from its almost unique properties within the isomerase family.
Assuntos
Cabelo/química , Queratinas/química , Isomerases de Dissulfetos de Proteínas/química , Animais , Bovinos , Cisteína/química , Humanos , Oxirredução , Dobramento de Proteína , Lã/químicaRESUMO
Wound dressings have experienced continuous and significant changes over the years based on the knowledge of the biochemical events associated with chronic wounds. The development goes from natural materials used to just cover and conceal the wound to interactive materials that can facilitate the healing process, addressing specific issues in non-healing wounds. These new types of dressings often relate with the proteolytic wound environment and the bacteria load to enhance the healing. Recently, the wound dressing research is focusing on the replacement of synthetic polymers by natural protein materials to delivery bioactive agents to the wounds. This article provides an overview on the novel protein-based wound dressings such as silk fibroin keratin and elastin. The improved properties of these dressings, like the release of antibiotics and growth factors, are discussed. The different types of wounds and the effective parameters of healing process will be reviewed.
Assuntos
Bandagens , Sistemas de Liberação de Medicamentos , Cicatrização , Animais , Antibacterianos/farmacologia , Colágeno/farmacologia , Elastina/farmacologia , Fibroínas/farmacologia , Humanos , Hidrólise , Queratinas/farmacologia , Polímeros/farmacologia , Ferimentos e Lesões/terapiaRESUMO
The unique properties of silk fibroin were combined with keratin to develop new wound-dressing materials. Silk fibroin/keratin (SF/K) films were prepared to reduce high levels of elastase found on chronic wounds. This improved biological function was achieved by the incorporation of a small peptide synthesized based on the reactive-site loop of the Bowman-Birk Inhibitor (BBI) protein. In vitro degradation and release were evaluated using porcine pancreatic elastase (PPE) solution as a model of wound exudate. It was found that biological degradation and release rate are highly dependent on film composition. Furthermore, the level of PPE activity can be tuned by changing the film composition, thus showing an innovative way of controlling the elastase-antielastase imbalance found on chronic wounds.
Assuntos
Fibroínas/metabolismo , Elastase Pancreática/antagonistas & inibidores , Fragmentos de Peptídeos/farmacologia , Inibidor da Tripsina de Soja de Bowman-Birk/farmacologia , Inibidores da Tripsina/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Bombyx , Proliferação de Células/efeitos dos fármacos , Queratinas/metabolismo , Camundongos , Microscopia de Força Atômica , Células NIH 3T3 , Elastase Pancreática/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Suínos , Inibidor da Tripsina de Soja de Bowman-Birk/química , Inibidores da Tripsina/químicaAssuntos
Fibroínas/química , Formiatos/química , Queratinas/química , Seda/química , Tripsina/metabolismo , Água/química , Amidas/química , Animais , Bombyx/química , Cristalização , Conformação Proteica , Estrutura Secundária de Proteína , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Termodinâmica , Lã/químicaRESUMO
Wool and silk were dissolved and used for the preparation of blended films. Two systems are proposed: (1) blend films of silk fibroin and keratin aqueous solutions and (2) silk fibroin and keratin dissolved in formic acid. The FTIR spectra of pure films cast from aqueous solutions indicated that the keratin secondary structure mainly consists of alpha-helix and random coil conformations. The IR spectrum of pure SF is characteristic of films with prevalently amorphous structure (random coil conformation). Pure keratin film cast from formic acid shows an increase in the amount of beta-sheet and disordered keratin structures. The FTIR pattern of SF dissolved in formic acid is characteristic of films with prevalently beta-sheet conformations with beta-sheet crystallites embedded in an amorphous matrix. The thermal behavior of the blends confirmed the FTIR results. DSC curve of pure SF is typical of amorphous SF and the curve of pure keratin show the characteristic melting peak of alpha-helices for the aqueous system. These patterns are no longer observed in the films cast from formic acid due to the ability of formic acid to induce crystallization of SF and to increase the amount of beta-sheet structures on keratin. The nonlinear trend of the different parameters obtained from FTIR analysis and DSC curves of both SF/keratin systems indicate that when proteins are mixed they do not follow additives rules but are able to establish intermolecular interactions. Degradable polymeric biomaterials are preferred candidates for medical applications. It was investigated the degradation behavior of both SF/keratin systems by in vitro enzymatic incubation with trypsin. The SF/keratin films cast from water underwent a slower biological degradation than the films cast from formic acid. The weight loss obtained is a function of the amount of keratin in the blend. This study encourages the further investigation of the type of matrices presented here to be applied whether in scaffolds for tissue engineering or as controlled release drug delivery vehicles.
Assuntos
Fibroínas/química , Formiatos/química , Queratinas/química , Seda/química , Tripsina/metabolismo , Água/química , Animais , Bombyx/química , Conformação Proteica , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Termodinâmica , Lã/químicaRESUMO
The influence of the peptide structure on its penetration inside hair was studied, together with the effect of hair bleaching (oxidation). For that reason, the outcome of positioning a charged sequence (KAKAK) either at the N or C terminal on hair penetration has been studied for peptides with 17 residues each. It was observed that the penetration of these peptides into hair was driven by electrostatic interactions, where the position of the charged group at the peptide structure was of major importance. The penetration was only achieved for damaged hair due to its higher negative charge at the membrane surface. It was also observed that the peptides were able to restore the original tensile strength of bleached hair. Consequently, the knowledge of hair surface properties is of extreme importance when designing peptides directed for hair treatment.
Assuntos
Cabelo/química , Peptídeos/química , Sequência de Aminoácidos , Cabelo/metabolismo , Humanos , Microscopia de Fluorescência , Modelos Moleculares , Dados de Sequência Molecular , Peptídeos/metabolismo , Eletricidade Estática , Relação Estrutura-Atividade , Propriedades de Superfície , Resistência à TraçãoRESUMO
The stability of immobilized and native Esperase, a commercial serine protease, was studied by incubating the enzymes in four formulations containing the same amount of anionic and non-ionic surfactants. The results show that the activity of the immobilized enzyme is not affected by the presence of detergents while the native enzyme lost 50% of activity after 20 min of incubation in these four formulations. The washing performance of the detergents prepared with the immobilized Esperase was studied on cotton and wool fabric samples stained with human blood and egg yolk, using as control the detergent containing native Esperase. The best stain removal for cotton samples stained with human blood was achieved using the detergent with immobilized Esperase. Several physical tests confirmed that wool keratin was not degraded by the immobilized Esperase, validating the ability to use formulated detergents containing this immobilized enzyme for safe wool domestic washing.