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1.
J Public Health (Oxf) ; 45(2): 330-337, 2023 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-36335426

RESUMO

BACKGROUND: Differential attainment has been widely observed in United Kingdom (UK) medical training, with minority ethnicity being associated with reduced success in recruitment and progression through training. Specialty training in Public Health in the UK recruits candidates with medical as well as non-medical backgrounds. At the request of the UK Faculty of Public Health and Health Education England, we sought to examine whether differential attainment may or may not be occurring in the multi-stage recruitment process. METHODS: We analysed 3 years of national recruitment data into Public Health specialty training to identify whether demographic characteristics including age, sex, ethnicity and professional background were associated with successful recruitment. RESULTS: In total 2252 applications between 2018 and 2020 were analysed. Candidates who were older, Asian, black or from backgrounds other than medicine were significantly less likely to progress from the psychometric testing stage than the white British group. Fewer statistically significant differences were observed at the final stage of recruitment involving interviews, group work and a written task. CONCLUSIONS: The findings suggest that older candidates those from some ethnic minority backgrounds and those from backgrounds other than medicine are disadvantaged by the current recruitment process, with differential attainment associated with the psychometric testing stage.


Assuntos
Etnicidade , Mão de Obra em Saúde , Grupos Minoritários , Humanos , Saúde Pública , Reino Unido , População Branca
2.
Int J Equity Health ; 21(1): 152, 2022 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-36324144

RESUMO

The health inequities faced by populations experiencing racial discrimination, including indigenous peoples and people of African descent, Roma, and other ethnic minorities, are an issue of global concern. Health systems have an important role to play in tackling these health inequities. Health systems based on comprehensive Primary Health Care (PHC) are best placed to tackle health inequities because PHC encompasses a whole-of-society approach to health. PHC includes actions to address the wider social determinants of health, multisectoral policy and action, intercultural and integrated healthcare services, community empowerment, and a focus on addressing health inequities. PHC can also serve as a platform for introducing specific actions to tackle racial discrimination and can act to drive wider societal change for tackling racial and ethnic health inequities.


Assuntos
Racismo , Humanos , Racismo/prevenção & controle , Desigualdades de Saúde , Disparidades nos Níveis de Saúde , Etnicidade , Atenção Primária à Saúde
4.
J Neurochem ; 137(2): 253-65, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26756888

RESUMO

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease with a poorly understood cause and no effective treatment. Given that calpains mediate neurodegeneration in other pathological states and are abnormally activated in ALS, we investigated the possible ameliorative effects of inhibiting calpain over-activation in hSOD1(G93A) transgenic (Tg) mice in vivo by neuron-specific over-expression of calpastatin (CAST), the highly selective endogenous inhibitor of calpains. Our data indicate that over-expression of CAST in hSOD1(G93A) mice, which lowered calpain activation to levels comparable to wild-type mice, inhibited the abnormal breakdown of cytoskeletal proteins (spectrin, MAP2 and neurofilaments), and ameliorated motor axon loss. Disease onset in hSOD1(G93A) /CAST mice compared to littermate hSOD1(G93A) mice is delayed, which accounts for their longer time of survival. We also find that neuronal over-expression of CAST in hSOD1(G93A) transgenic mice inhibited production of putative neurotoxic caspase-cleaved tau and activation of Cdk5, which have been implicated in neurodegeneration in ALS models, and also reduced the formation of SOD1 oligomers. Our data indicate that inhibition of calpain with CAST is neuroprotective in an ALS mouse model. CAST (encoding calpastatin) inhibits hyperactivated calpain to prevent motor neuron disease operating through a cascade of events as indicated in the schematic, with relevance to amyotrophic lateral sclerosis (ALS). We propose that over-expression of CAST in motor neurons of hSOD1(G93A) mice inhibits activation of CDK5, breakdown of cytoskeletal proteins (NFs, MAP2 and Tau) and regulatory molecules (Cam Kinase IV, Calcineurin A), and disease-causing proteins (TDP-43, α-Synuclein and Huntingtin) to prevent neuronal loss and delay neurological deficits. In our experiments, CAST could also inhibit cleavage of Bid, Bax, AIF to prevent mitochondrial, ER and lysosome-mediated cell death mechanisms. Similarly, CAST over-expression in neurons attenuated pathological effects of TDP-43, α-synuclein and Huntingtin. These results suggest a potential value of specific small molecule inhibitors of calpains in delaying the development of ALS. Read the Editorial Highlight for this article on page 140.


Assuntos
Proteínas de Ligação ao Cálcio/farmacologia , Inibidores de Cisteína Proteinase/farmacologia , Neurônios Motores/efeitos dos fármacos , Superóxido Dismutase/genética , Fatores Etários , Esclerose Lateral Amiotrófica/tratamento farmacológico , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Animais , Axônios/patologia , Calpaína/metabolismo , Morte Celular/efeitos dos fármacos , Morte Celular/genética , Quinase 5 Dependente de Ciclina/metabolismo , Proteínas do Citoesqueleto/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Regulação da Expressão Gênica , Humanos , Camundongos , Camundongos Transgênicos , Atividade Motora/efeitos dos fármacos , Atividade Motora/genética , Neurônios Motores/citologia , Neurônios Motores/metabolismo , Degeneração Neural/tratamento farmacológico , Degeneração Neural/genética , Degeneração Neural/patologia , Medula Espinal/citologia
5.
Hum Mol Genet ; 23(15): 3975-89, 2014 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-24619358

RESUMO

Lewy bodies, a pathological hallmark of Parkinson's disease (PD), contain aggregated alpha-synuclein (αSyn), which is found in several modified forms and can be discovered phosphorylated, ubiquitinated and truncated. Aggregation-prone truncated species of αSyn caused by aberrant cleavage of this fibrillogenic protein are hypothesized to participate in its sequestration into inclusions subsequently leading to synaptic dysfunction and neuronal death. Here, we investigated the role of calpain cleavage of αSyn in vivo by generating two opposing mouse models. We crossed into human [A30P]αSyn transgenic (i) mice deficient for calpastatin, a calpain-specific inhibitor, thus enhancing calpain activity (SynCAST(-)) and (ii) mice overexpressing human calpastatin leading to reduced calpain activity (SynCAST(+)). As anticipated, a reduced calpain activity led to a decreased number of αSyn-positive aggregates, whereas loss of calpastatin led to increased truncation of αSyn in SynCAST(-). Furthermore, overexpression of calpastatin decreased astrogliosis and the calpain-dependent degradation of synaptic proteins, potentially ameliorating the observed neuropathology in [A30P]αSyn and SynCAST(+) mice. Overall, our data further support a crucial role of calpains, particularly of calpain 1, in the pathogenesis of PD and in disease-associated aggregation of αSyn, indicating a therapeutic potential of calpain inhibition in PD.


Assuntos
Proteínas de Ligação ao Cálcio/genética , Calpaína/genética , Doença de Parkinson/genética , Agregação Patológica de Proteínas/genética , alfa-Sinucleína/genética , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Calpaína/antagonistas & inibidores , Calpaína/metabolismo , Modelos Animais de Doenças , Regulação da Expressão Gênica , Humanos , Corpos de Lewy/metabolismo , Corpos de Lewy/patologia , Camundongos , Camundongos Transgênicos , Neurônios/metabolismo , Neurônios/patologia , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Agregados Proteicos , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia , Proteólise , Transdução de Sinais , Sinapses/metabolismo , Sinapses/patologia , alfa-Sinucleína/metabolismo
6.
J Neurosci ; 34(28): 9222-34, 2014 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-25009256

RESUMO

Tau pathogenicity in Alzheimer's disease and other tauopathies is thought to involve the generation of hyperphosphorylated, truncated, and oligomeric tau species with enhanced neurotoxicity, although the generative mechanisms and the implications for disease therapy are not well understood. Here, we report a striking rescue from mutant tau toxicity in the JNPL3 mouse model of tauopathy. We show that pathological activation of calpains gives rise to a range of potentially toxic forms of tau, directly, and by activating cdk5. Calpain overactivation in brains of these mice is accelerated as a result of the marked depletion of the endogenous calpain inhibitor, calpastatin. When levels of this inhibitor are restored in neurons of JNPL3 mice by overexpressing calpastatin, tauopathy is prevented, including calpain-mediated breakdown of cytoskeletal proteins, cdk5 activation, tau hyperphosphorylation, formation of potentially neurotoxic tau fragments by either calpain or caspase-3, and tau oligomerization. Calpastatin overexpression also prevents loss of motor axons, delays disease onset, and extends survival of JNPL3 mice by 3 months to within the range of normal lifespan. Our findings support the therapeutic promise of highly specific calpain inhibition in the treatment of tauopathies and other neurodegenerative states.


Assuntos
Comportamento Animal/efeitos dos fármacos , Proteínas de Ligação ao Cálcio/administração & dosagem , Calpaína/antagonistas & inibidores , Longevidade/efeitos dos fármacos , Tauopatias/prevenção & controle , Tauopatias/fisiopatologia , Animais , Calpaína/metabolismo , Inibidores de Cisteína Proteinase/administração & dosagem , Feminino , Masculino , Camundongos , Camundongos Transgênicos , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Degeneração Neural/prevenção & controle , Taxa de Sobrevida , Tauopatias/patologia , Resultado do Tratamento , Proteínas tau/efeitos dos fármacos , Proteínas tau/genética
7.
Heliyon ; 10(6): e27588, 2024 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-38515726

RESUMO

Background: University students are more at risk of mental illness compared with the general population. Declaration of a global COVID-19 pandemic led the Bangladesh government in March 2020 to implement a national lockdown, home quarantining, social distancing measures, and closure of educational institutions. We aimed to explore the impact of lockdown on the mental health and well-being of university students in Bangladesh. Methods: A nested mixed-methods survey design was undertaken using a semi structured questionnaire and in-depth interviews conducted by telephone of 73 university students (mean age of 22 years, range 18 to 26-years-old) attending public and private academic institutions in Dhaka. A questionnaire was developed de-novo and pre-tested. Qualitative, open-ended questions were used to understand experiences regarding students' mental health and well-being, their perceptions of COVID-19, and coping strategies. Results: Fifty nine percent of students reported that lockdown had a significant impact on their mental health and well-being. They described difficulties with social isolation and loneliness, motivation, and interpersonal conflict within families. Students' knowledge of COVID-19 were high with television, newspapers, online, and social media were main sources of information; few relied on government reports. Most pressing concerns were timely graduation and employment (83%), not being able to socialize (46%), being stuck at home (37%), and financial difficulties regarding university fees (29%). Additional underlying stressors included financial insecurity of respondents' households and parental health. Coping strategies included watching television or films, online meetings with friends, social media, as well interactions with family. Conclusion: As a result of Bangladesh's first national lockdown, university students experienced negative effects on their mental health and well-being. There is an urgent need for greater proactive measures within educational settings, such as mental health literacy programmes and diagnosis management that could mitigate and prevent adverse impacts of future lockdowns.

8.
Glob Ment Health (Camb) ; 11: e37, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38572252

RESUMO

This study explores Bangladesh's mental health services from an individual- and system-level perspective and provides insights and recommendations for strengthening it's mental health system. We conducted 13 in-depth interviews and 2 focus group discussions. Thirty-one participants were recruited using a combination of purposive and snowball sampling methods. All interviews and group discussions were audio-recorded and transcribed, and key findings were translated from Bengali to English. Data were coded manually and analysed using a thematic and narrative analysis approach. Stakeholders perceived scarcity of service availability at the peripheral level, shortage of professionals, weak referral systems, lack of policy implementation and regulatory mechanisms were significant challenges to the mental health system in Bangladesh. At the population level, low levels of mental health literacy, high societal stigma, and treatment costs were barriers to accessing mental healthcare. Key recommendations included increasing the number of mental health workers and capacity building, strengthening regulatory mechanisms to enhance the quality of care within the health systems, and raising awareness about mental health. Introducing measures that relate to tackling stigma, mental health literacy as well as building the capacity of the health workforce and governance systems will help ensure universal mental health coverage.

9.
bioRxiv ; 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38854023

RESUMO

Huntington's disease (HD) is caused by expansion of the polyglutamine stretch in huntingtin protein (HTT) resulting in hallmark aggresomes/inclusion bodies (IBs) composed of mutant huntingtin protein (mHTT) and its fragments. Stimulating autophagy to enhance mHTT clearance is considered a potential therapeutic strategy for HD. Our recent evaluation of the autophagic-lysosomal pathway (ALP) in human HD brain reveals upregulated lysosomal biogenesis and relatively normal autophagy flux in early Vonsattel grade brains, but impaired autolysosome clearance in late grade brains, suggesting that autophagy stimulation could have therapeutic benefits as an earlier clinical intervention. Here, we tested this hypothesis by crossing the Q175 HD knock-in model with our autophagy reporter mouse TRGL ( T hy-1- R FP- G FP- L C3) to investigate in vivo neuronal ALP dynamics. In the Q175 and/or TRGL/Q175 mice, mHTT was detected in autophagic vacuoles and also exhibited high level colocalization with autophagy receptors p62/SQSTM1 and ubiquitin in the IBs. Compared to the robust lysosomal pathology in late-stage human HD striatum, ALP alterations in Q175 models are also late-onset but milder that included a lowered phospho-p70S6K level, lysosome depletion and autolysosome elevation including more poorly acidified autolysosomes and larger-sized lipofuscin granules, reflecting impaired autophagic flux. Administration of a mTOR inhibitor to 6-mo-old TRGL/Q175 normalized lysosome number, ameliorated aggresome pathology while reducing mHTT-, p62- and ubiquitin-immunoreactivities, suggesting beneficial potential of autophagy modulation at early stages of disease progression.

10.
J Neurosci ; 32(25): 8501-8, 2012 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-22723690

RESUMO

Peripherin, a neuronal intermediate filament protein implicated in neurodegenerative disease, coexists with the neurofilament triplet proteins [neurofilament light (NFL), medium (NFM), and heavy (NFH) chain] but has an unknown function. The earlier peak expression of peripherin than the triplet during brain development and its ability to form homopolymers, unlike the triplet, which are obligate heteropolymers, have supported a widely held view that peripherin and neurofilament triplets form separate filament systems. However, here, we demonstrate that, despite a postnatal decline in expression, peripherin is as abundant as the triplet in the adult PNS and exists in a relatively fixed stoichiometry with these subunits. Peripherin exhibits a distribution pattern identical to those of triplet proteins in sciatic axons and colocalizes with NFL on single neurofilaments by immunogold electron microscopy. Peripherin also coassembles into a single network of filaments containing NFL, NFM, and NFH with and without α-internexin in quadruple- or quintuple-transfected SW13vim(-) cells. Genetically deleting NFL in mice dramatically reduces peripherin content in sciatic axons. Moreover, peripherin mutations has been shown to disrupt the neurofilament network in transfected SW13vim(-) cells. These data show that peripherin and the neurofilament proteins are functionally interdependent. The results strongly support the view that, rather than forming an independent structure, peripherin is a subunit of neurofilaments in the adult PNS. Our findings provide a basis for its close relationship with neurofilaments in PNS diseases associated with neurofilament accumulation.


Assuntos
Axônios/metabolismo , Sistema Nervoso Central/metabolismo , Proteínas de Filamentos Intermediários/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas de Neurofilamentos/metabolismo , Sistema Nervoso Periférico/metabolismo , Animais , Anticorpos Monoclonais , Axônios/ultraestrutura , Western Blotting , Sistema Nervoso Central/citologia , Sistema Nervoso Central/ultraestrutura , Eletroforese em Gel de Poliacrilamida , Feminino , Imunofluorescência , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Imunoeletrônica , Sistema Nervoso Periférico/citologia , Sistema Nervoso Periférico/ultraestrutura , Periferinas , Nervo Isquiático/citologia , Nervo Isquiático/metabolismo , Transfecção
11.
J Fluoresc ; 23(2): 311-21, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23212130

RESUMO

This is the first report of inactivation of xyloglucanase from Thermomonospora sp by pepstatin A, a specific inhibitor towards aspartic proteases. The steady state kinetics revealed a reversible, competitive, two-step inhibition mechanism with IC 50 and K i values of 3.5 ± 0.5 µM and 1.25 ± 0.5 µM respectively. The rate constants determined for the isomerization of EI to EI(*) and the dissociation of EI* were 14.5 ± 1.5 × 10(-5) s(-1) and 2.85 ± 1.2 × 10(-8) s(-1) respectively, whereas the overall inhibition constant K i(*) was 27 ± 1 nM. The conformational changes induced upon inhibitor binding to xyloglucanase were monitored by fluorescence analysis and the rate constants derived were in agreement with the kinetic data. The abolished isoindole fluorescence of o-phthalaldehyde (OPTA)-labeled xyloglucanase and far UV analysis suggested that pepstatin binds to the active site of the enzyme. Our results revealed that the inactivation of xyloglucanase is due to the interference in the electronic microenvironment and disruption of the hydrogen-bonding network between the essential histidine and other residues involved in catalysis.


Assuntos
Ácido Aspártico Endopeptidases/antagonistas & inibidores , Glicosídeo Hidrolases/antagonistas & inibidores , Pepstatinas/farmacologia , Inibidores de Proteases/farmacologia , Dicroísmo Circular , Glicosídeo Hidrolases/isolamento & purificação , Cinética , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , o-Ftalaldeído/química
12.
Natl Med J India ; 26(5): 291-4, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-25017839

RESUMO

The National Sample Survey (NSS), instituted in 1950, was the brainchild of Professor Mahalanobis, widely regarded as the father of Indian statistics.1 His ambition was to obtain and quantify comprehensive information on an annual basis on the socio- economic, demographic, agricultural and other profiles of the country, both at the national and state levels. The NSS is a multi- stage, multi-subject and multi-purpose cross-sectional survey, which is conducted annually and covers topics of current interest.


Assuntos
Inquéritos Epidemiológicos , Saúde Pública , Projetos de Pesquisa , Estudos Transversais , Humanos , Índia
13.
Int J Popul Data Sci ; 8(4): 2166, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38481434

RESUMO

Local authorities are central to the implementation of English Integrated Care Systems' health inequalities agendas, embedding public health into population health management planning. They work with partners to deliver a range of 'health determinant' services and facilities for people in a defined geographic area. This work is substantially premised on the use of cross-sectoral data that is linked at the individual level, readily available, longitudinal and contemporaneous. However, multiple challenges exist to such data availability. This paper elaborates upon these challenges to local authority public health systems and their potential solutions.


Assuntos
Serviços de Saúde , Saúde Pública , Humanos , Desigualdades de Saúde
14.
BMJ Open ; 13(3): e069738, 2023 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-36894198

RESUMO

OBJECTIVES: To determine how current psychometric testing approaches used in selection of postgraduate training in UK Public Health are associated with socioeconomic and sociocultural background of applicants (including ethnicity). DESIGN: Observational study using contemporaneous data collected during recruitment and psychometric test scores. SETTING: Assessment centre of UK national Public Health recruitment for postgraduate Public Health training. The assessment centre element of selection comprises three psychometric assessments: Rust Advanced Numerical Reasoning, Watson-Glaser Critical Thinking Assessment II and Public Health situational judgement test. PARTICIPANTS: 629 applicants completed the assessment centre in 2021. 219 (34.8%) were UK medical graduates, 73 (116%) were international medical graduates and 337 (53.6%) were from backgrounds other than medicine. MAIN OUTCOME MEASURE: Multivariable-adjusted progression statistics in the form of adjusted OR (aOR), accounting for age, sex, ethnicity, professional background and surrogate measures of familial socioeconomic and sociocultural status. RESULTS: 357 (56.8%) candidates passed all three psychometric tests. Candidate characteristics negatively associated with progression were black ethnicity (aOR 0.19, 0.08 to 0.44), Asian ethnicity (aOR 0.35, 0.16 to 0.71) and coming from a non-UK medical graduate background (aOR 0.05, 0.03 to 0.12); similar differential attainment was observed in each of the psychometric tests. Even within the UK-trained medical cohort, candidates from white British backgrounds were more likely to progress than those from ethnic minorities (89.2% vs 75.0%, p=0.003). CONCLUSION: Although perceived to mitigate the risks of conscious and unconscious bias in selection to medical postgraduate training, these psychometric tests demonstrate unexplained variation that suggests differential attainment. Other specialties should enhance their data collection to evaluate the impact of differential attainment on current selection processes and take forward opportunities to mitigate differential attainment where possible.


Assuntos
Avaliação Educacional , Saúde Pública , Humanos , Psicometria , Etnicidade , Reino Unido
15.
Front Public Health ; 11: 1322831, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38155894

RESUMO

This article makes a call for attention to paid on the development of a research agenda for studying the impact of climatic events on youth mental health in the Caribbean. It details the climate injustices that the region faces and the potential mental health problem which can arise from climatic events. It makes a call for interdisciplinary research and a multi stakeholder approach to dealing with this potential issue.


Assuntos
Mudança Climática , Saúde Mental , Humanos , Adolescente , Índias Ocidentais , Região do Caribe , Etnicidade
16.
Autophagy ; 19(4): 1277-1292, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36131358

RESUMO

How macroautophagy/autophagy influences neurofilament (NF) proteins in neurons, a frequent target in neurodegenerative diseases and injury, is not known. NFs in axons have exceptionally long half-lives in vivo enabling formation of large stable supporting networks, but they can be rapidly degraded during Wallerian degeneration initiated by a limited calpain cleavage. Here, we identify autophagy as a previously unrecognized pathway for NF subunit protein degradation that modulates constitutive and inducible NF turnover in vivo. Levels of NEFL/NF-L, NEFM/NF-M, and NEFH/NF-H subunits rise substantially in neuroblastoma (N2a) cells after blocking autophagy either with the phosphatidylinositol 3-kinase (PtdIns3K) inhibitor 3-methyladenine (3-MA), by depleting ATG5 expression with shRNA, or by using both treatments. In contrast, activating autophagy with rapamycin significantly lowers NF levels in N2a cells. In the mouse brain, NF subunit levels increase in vivo after intracerebroventricular infusion of 3-MA. Furthermore, using tomographic confocal microscopy, immunoelectron microscopy, and biochemical fractionation, we demonstrate the presence of NF proteins intra-lumenally within autophagosomes (APs), autolysosomes (ALs), and lysosomes (LYs). Our findings establish a prominent role for autophagy in NF proteolysis. Autophagy may regulate axon cytoskeleton size and responses of the NF cytoskeleton to injury and disease.


Assuntos
Autofagia , Filamentos Intermediários , Camundongos , Animais , Autofagia/fisiologia , Proteólise , Filamentos Intermediários/metabolismo , Proteínas de Neurofilamentos/genética , Proteínas de Neurofilamentos/metabolismo , Neurônios/metabolismo
17.
Microbiology (Reading) ; 158(Pt 7): 1897-1907, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22493301

RESUMO

A low-molecular-mass aspartic protease inhibitor was isolated from a novel Penicillium sp. The inhibitor was purified to homogeneity, as shown by reversed-phase HPLC and SDS-PAGE. The M(r) of the inhibitor was 1585 and the amino acid composition showed the presence of D, D, D, E, A, K, L, Y, H, I and W residues. The steady-state kinetic interactions of Aspergillus saitoi aspartic protease with the inhibitor revealed the reversible, competitive, time-dependent tight-binding nature of the inhibitor, with IC(50) and K(i) values of 1.8 and 0.85 µM, respectively. Fluorescence spectroscopy and circular dichroism analysis showed that inactivation of the enzyme was due to binding of the inhibitor to the active site. The inhibitor was found to inhibit mycelial growth and spore germination of Aspergillus fumigatus and Aspergillus niger in vitro with MIC values of 1.65 and 0.30 µg ml(-1), respectively. This study will potentially open the way towards the development of a tight-binding peptidic inhibitor against fungal aspartic proteases to combat human fungal infections.


Assuntos
Ácido Aspártico Proteases/antagonistas & inibidores , Penicillium/enzimologia , Inibidores de Proteases/isolamento & purificação , Antifúngicos/química , Antifúngicos/isolamento & purificação , Antifúngicos/metabolismo , Ácido Aspártico Proteases/metabolismo , Aspergillus fumigatus/efeitos dos fármacos , Aspergillus fumigatus/crescimento & desenvolvimento , Aspergillus niger/efeitos dos fármacos , Aspergillus niger/crescimento & desenvolvimento , Cromatografia Líquida de Alta Pressão , Dicroísmo Circular , DNA Fúngico/química , DNA Fúngico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Eletroforese em Gel de Poliacrilamida , Humanos , Concentração Inibidora 50 , Cinética , Dados de Sequência Molecular , Penicillium/genética , Inibidores de Proteases/química , Inibidores de Proteases/metabolismo , Análise de Sequência de DNA , Espectrometria de Fluorescência
18.
Extremophiles ; 16(1): 135-46, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22120834

RESUMO

Xyloglucanase from an extracellular culture filtrate of alkalothermophilic Thermomonospora sp. was purified to homogeneity with a molecular weight of 144 kDa as determined by SDS-PAGE and exhibited specificity towards xyloglucan with apparent K (m) of 1.67 mg/ml. The enzyme was active at a broad range of pH (5-8) and temperatures (40-80°C). The optimum pH and temperature were 7 and 70°C, respectively. The enzyme retained 100% activity at 50°C for 60 h with half-lives of 14 h, 6 h and 7 min at 60, 70 and 80°C, respectively. The kinetics of thermal denaturation revealed that the inactivation at 80°C is due to unfolding of the enzyme as evidenced by the distinct red shift in the wavelength maximum of the fluorescence profile. Xyloglucanase activity was positively modulated in the presence of Zn(2+), K(+), cysteine, ß-mercaptoethanol and polyols. Thermostability was enhanced in the presence of additives (polyols and glycine) at 80°C. A hydrolysis of 55% for galactoxyloglucan (GXG) from tamarind kernel powder (TKP) was obtained in 12 h at 60°C and 6 h at 70°C using thermostable xyloglucanases, favouring a reduction in process time and enzyme dosage. The enzyme was stable in the presence of commercial detergents (Ariel), indicating its potential as an additive to laundry detergents.


Assuntos
Glicosídeo Hidrolases/metabolismo , Bactérias Gram-Positivas/enzimologia , Sequência de Bases , Primers do DNA , Eletroforese em Gel de Poliacrilamida , Estabilidade Enzimática , Glicosídeo Hidrolases/química , Concentração de Íons de Hidrogênio , Hidrólise , Peso Molecular , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Especificidade por Substrato
19.
Indian J Biochem Biophys ; 49(3): 189-94, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22803334

RESUMO

Cellulases find increasing prominence in sustainable production of fuel and feedstock from lignocellulosic biomass. The purification and biochemical characterization of individual components of cellulase complex is important to understand the mechanism of their action for the solubilization of crystalline cellulose. In this study, an extra-cellular endoglucanase isolated from culture filtrate of Penicillium pinophilum MS 20 was purified to homogeneity by ammonium sulphate precipitation, ion-exchange chromatography and gel filtration. The purified endoglucanase (specific activity 69 U/mg) was a monomeric protein with molecular mass of 42 kDa, as determined by SDS-PAGE. The endoglucanase was active over a broad range of pH (4-7) with maximum activity at pH 5 and showed optimum temperature of 50 degrees C. It retained 100% activity at 50 degrees C for 6 h and half- lives of 4 h and 3 h at 60 degrees C and 70 degrees C, respectively. The kinetic constants for the endoglucanase determined with carboxymethyl cellulose as substrate were V(max) of 72.5 U/mg and apparent K(m) of 4.8 mg/ml. The enzyme also showed moderate activity towards H3PO4 swollen cellulose and p-nitrophenyl beta-D-glucoside, but no activity towards filter paper, Avicel and oat spelt xylan. The activity was positively modulated by 47, 32 and 25% in the presence of Co2+, Zn2+ and Mg2+, respectively to the reaction mixture. The wide pH stability (4-7) and temperature stability up to 50 degrees C of endoglucanase makes the enzyme suitable for use in cellulose saccharification at moderate temperature and pH.


Assuntos
Celulase/química , Penicillium/enzimologia , Celulase/isolamento & purificação , Celulase/metabolismo , Eletroforese em Gel de Poliacrilamida , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Especificidade por Substrato
20.
Nat Neurosci ; 25(6): 688-701, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35654956

RESUMO

Autophagy is markedly impaired in Alzheimer's disease (AD). Here we reveal unique autophagy dysregulation within neurons in five AD mouse models in vivo and identify its basis using a neuron-specific transgenic mRFP-eGFP-LC3 probe of autophagy and pH, multiplex confocal imaging and correlative light electron microscopy. Autolysosome acidification declines in neurons well before extracellular amyloid deposition, associated with markedly lowered vATPase activity and build-up of Aß/APP-ßCTF selectively within enlarged de-acidified autolysosomes. In more compromised yet still intact neurons, profuse Aß-positive autophagic vacuoles (AVs) pack into large membrane blebs forming flower-like perikaryal rosettes. This unique pattern, termed PANTHOS (poisonous anthos (flower)), is also present in AD brains. Additional AVs coalesce into peri-nuclear networks of membrane tubules where fibrillar ß-amyloid accumulates intraluminally. Lysosomal membrane permeabilization, cathepsin release and lysosomal cell death ensue, accompanied by microglial invasion. Quantitative analyses confirm that individual neurons exhibiting PANTHOS are the principal source of senile plaques in amyloid precursor protein AD models.


Assuntos
Doença de Alzheimer , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Autofagia , Modelos Animais de Doenças , Concentração de Íons de Hidrogênio , Lisossomos/metabolismo , Camundongos , Camundongos Transgênicos , Neurônios/metabolismo , Placa Amiloide/metabolismo
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