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1.
BMC Public Health ; 21(1): 1874, 2021 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-34657616

RESUMO

BACKGROUND: Lead poisoning prevention efforts include preparing and disseminating informational materials such as brochures and pamphlets to increase awareness of lead poisoning, lead exposures and lead poisoning prevention. However, studies have demonstrated that patient education materials for diseases and health conditions are prepared at a reading level that is higher than the recommended 7th-8th grade reading level. This study, therefore, aims to assess the reading levels of lead poisoning informational materials. METHODS: Lead poisoning materials (N = 31) were accessed from three states; Michigan, New York and Pennsylvania. The readability levels of the materials were assessed using the Flesh Kincaid Grade Level readability test. The Kruskal-Wallis test was conducted to determine if the readability levels differed between the materials obtained from the different states. Thematic content analyses were carried out to assess the inclusion of four themes; definition of lead poisoning, risk factors and exposures, testing and referral and prevention covering 12 subtopics. The Wilcoxon rank sum test was used to examine if there was a difference in the number of subtopics by readability level (dichotomized to >8th grade and < 8th grade). RESULTS: The median readability level of the informational materials was 6.7 (IQR: 5.1-8.1). However, there was variability in the readability levels of the materials (range 3.5 to 10.6); materials obtained from Michigan had the highest median reading level of 8.1 (IQR: 6.9-9.0) followed by Pennsylvania. Heterogeneity was observed in the content of the materials. Most of the materials (80%) from Michigan focused on water as a source of lead poisoning, whereas materials from New York and Pennsylvania focused on lead-based paint and other sources. The materials prepared at >8th grade reading level contained fewer topics than materials prepared at <8th grade reading level. CONCLUSIONS: We find that the materials were often prepared at reading levels lower than the recommended 8th grade reading level. However, there is variability in the reading levels and in the content of the materials. While the materials met the general readability guidelines, they did not necessarily meet the needs of specific groups, especially groups at risk.


Assuntos
Letramento em Saúde , Intoxicação por Chumbo , Compreensão , Escolaridade , Humanos , Internet , Intoxicação por Chumbo/prevenção & controle , Michigan , Folhetos
2.
AIDS Behav ; 23(8): 2130-2137, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30387024

RESUMO

In adults living with HIV, pharmacy refill data are good predictors of virologic failure (VF). The utility of pharmacy refill data for predicting VF in adolescents has not been reported. We evaluated data from 291 adolescents on antiretroviral therapy. The main outcome measure was VF, defined as two consecutive HIV viral load measurements ≥ 400 copies/mL during 24-months of follow-up. Pharmacy refill non-adherence was defined as two consecutive refill adherence measurements < 95% during the same period. Fifty-three (18%) adolescents experienced VF. One hundred twenty-eight (44%) adolescents had refill non-adherence. Refill non-adherence had poor discriminative ability for indicating VF (receiver operating characteristic AUC = 0.60). Sensitivity and specificity for predicting VF was poor (60% (95% CI 46-74%) and 60% (95% CI 53-66%), respectively). The lack of a viable surrogate for VF in adolescents highlights the urgent need for more access to virologic testing and novel methods of monitoring adolescent treatment adherence.


Assuntos
Fármacos Anti-HIV/uso terapêutico , Infecções por HIV/tratamento farmacológico , Adesão à Medicação , Assistência Farmacêutica/estatística & dados numéricos , Carga Viral/efeitos dos fármacos , Adolescente , Adulto , Botsuana , Feminino , Humanos , Masculino , Aceitação pelo Paciente de Cuidados de Saúde , Farmácias , Valor Preditivo dos Testes , Curva ROC , Resultado do Tratamento
3.
AIDS Care ; 30(2): 224-231, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28643572

RESUMO

Levels of adherence to HIV treatment are lower among adolescents compared with older and younger individuals receiving similar therapies. We purposely sampled the most and least adherent adolescents from a 300-adolescent longitudinal HIV treatment adherence study in Gaborone, Botswana. Multiple objective and subjective measures of adherence were available and study participants were selected based on sustained patterns of either excellent or poor adherence over a one-year period. Focus group discussions (FGD) and in-depth interviews (IDI) were conducted with the adolescents and a subset of their caregivers with the goal of revealing barriers and facilitators of adherence. Focus groups were segregated by adherence classification of the participants. Following coding of transcripts, matrices were developed based on participants' adherence classifications in order to clarify differences in themes generated by individuals with different adherence characteristics. 47 adolescents and 25 adults were included. The non-adherent adolescents were older than the adherent adolescents (median age 18 years (IQR 16-19) vs. 14 years (IQR 12-15 years)), with median time on treatment near 10 years in both groups. Interference with daily activities, concerns about stigma and discrimination, side effects, denial of HIV status, and food insecurity arose as challenges to adherence among both those who were consistently adherent and those who were poorly-adherent to their medications. Low outcome expectancy, treatment fatigue, mental health and substance use problems, and mismatches between desired and received social support were discussed only among poorly adherent adolescents and their caregivers. Challenges raised only among adolescents and caregivers in the non-adherent groups are hypothesis-generating, identifying areas that may have a greater contribution to poor outcomes than challenges faced by both adherent and non-adherent adolescents. The contribution of these factors to poor outcomes should be explored in future studies.


Assuntos
Terapia Antirretroviral de Alta Atividade/psicologia , Discriminação Psicológica , Infecções por HIV/tratamento farmacológico , Adesão à Medicação/psicologia , Adesão à Medicação/estatística & dados numéricos , Estigma Social , Adolescente , Botsuana , Cuidadores , Feminino , Grupos Focais , Infecções por HIV/psicologia , Humanos , Entrevistas como Assunto , Estudos Longitudinais , Masculino , Manejo da Dor , Pobreza , Apoio Social , Fatores de Tempo , Adulto Jovem
4.
Public Health Nurs ; 35(3): 238-245, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29424085

RESUMO

OBJECTIVES: To design and implement a case study on the cervical cancer screening program in Botswana to teach public and global health competencies to undergraduate nursing students. DESIGN AND SAMPLE: The case study was developed following a review of the literature on the epidemiology and health policies of cervical cancer in Botswana, and an interview with an obstetrician/gynecologist engaged in both clinical practice and research in Botswana. The case study has been implemented over seven semesters to students enrolled in the Nursing in the Community course at the University of Pennsylvania. Approximately 75-100 students are enrolled each semester. MEASURES: Student's perceptions of epidemiologic skills gained and group functioning. Students responded to an open-ended question about lessons learned and offered suggestions to improve the learning experience. RESULTS: Faculty assessment of student deliverables demonstrated that students achieved the learning objectives and mastered necessary competencies. More than 70% (n = 69) of the students indicated that they acquired relevant skills at greater than a satisfactory level. Generally, students had great experiences working in groups measured across five dimensions: engagement/contribution, creativity/resilience, on task/works independently, social interaction/communication, and preparedness. However, isolated cases of poor group functioning were reported for engagement/contribution, and creativity/resilience. CONCLUSION: The case study, which has been revised with respect to length, content and group processes, has been valuable in educating undergraduate nursing students in a more engaging way that mimics real life public health nursing scenarios. Students achieved both public and global health competencies through participation in the case study.


Assuntos
Competência Clínica , Detecção Precoce de Câncer , Bacharelado em Enfermagem/organização & administração , Saúde Global/educação , Enfermagem em Saúde Pública/educação , Neoplasias do Colo do Útero/prevenção & controle , Botsuana , Feminino , Humanos , Aprendizagem , Pesquisa em Educação em Enfermagem , Pesquisa em Avaliação de Enfermagem , Estudos de Casos Organizacionais , Estudantes de Enfermagem/psicologia , Estudantes de Enfermagem/estatística & dados numéricos
6.
Artigo em Inglês | MEDLINE | ID: mdl-33466621

RESUMO

Lead poisoning is a preventable condition that continues to affect thousands of children each year. Given that local governments and municipalities are eligible to apply for federal funds to perform lead remediation in low-income family homes, we sought to understand how lead poisoning knowledge levels may affect the uptake of these funds. We recruited and conducted 28 in-depth, semi-structured interviews with community members from Lancaster County in the state of Pennsylvania in the USA. We audio-recorded and transcribed each interview, and analyzed each transcript for salient themes. The interviewed participants displayed a varying degree of knowledge about lead and lead poisoning. Most of the participants were unaware of the lead paint remediation funds. Participants learned about lead from various sources, such as social media, and personal experiences with lead poisoning appeared to enhance knowledge. Some participants assumed lead poisoning prevention would be addressed by other stakeholders if necessary, including healthcare professionals and landlords. The results of this study suggest that in order to increase the timely uptake of the remediation funds, community-based organizations should design interventions that aim to increase awareness and knowledge about lead poisoning and lead poisoning prevention. These interventions should be tailored for different audiences including community members, healthcare professionals, and landlords.


Assuntos
Administração Financeira , Intoxicação por Chumbo , Criança , Cidades , Exposição Ambiental , Humanos , Chumbo , Intoxicação por Chumbo/prevenção & controle , Pintura , Pennsylvania
7.
J Adolesc Health ; 67(4): 502-508, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32340848

RESUMO

PURPOSE: This study aimed to determine if disclosure of HIV status to adolescents impacted their medication adherence and how medication autonomy might explain observed effects. METHODS: Three hundred adolescents on HIV treatment using electronic medication monitors were followed for 24 months while undergoing routine care. One hundred six of the adolescents were HIV disclosure-naïve and HIV status disclosure in this group was assessed quarterly. Analyses included data from the 75 adolescents who experienced disclosure during the study providing adherence and autonomy data both predisclosure and postdisclosure. Segmented generalized estimating equations were used to examine the trend of adherence and autonomy predisclosure and postdisclosure. Covariates assessed include age at disclosure, sex, and orphan status. RESULTS: Median age at study entry was 12.2 years (interquartile range 11.6-12.9). Incident disclosure occurred in 75 (71%) of the adolescents at a median age of 13.1 years (interquartile range 12.5-13.9). Adherence decreased by 11% (95% confidence interval [CI] 7-15, p < .001) during the predisclosure period and by 22% (95% CI 9-36, p = .001) during the postdisclosure period. Adolescents' autonomy over their medication-taking increased over time, but disclosure did not impact the rate of increase in measured medication-taking autonomy. On a scale of 1-4 assessing autonomy (1 = receiving directly observed therapy and 4 = taking medicines mostly without supervision), autonomy increased by an average of .03 units/month (95% CI .02-.03, p < .001) predisclosure and by .05 units/month (95% CI -.01 to .11, p = .42) postdisclosure. CONCLUSIONS: The findings suggest that, among perinatally HIV infected adolescents, HIV status disclosure may adversely impact treatment adherence. Postdisclosure support to HIV infected adolescents should be intensified.


Assuntos
Crianças Órfãs , Infecções por HIV , Adolescente , Botsuana , Criança , Revelação , Infecções por HIV/tratamento farmacológico , Humanos , Adesão à Medicação
8.
Artigo em Inglês | MEDLINE | ID: mdl-31252687

RESUMO

BACKGROUND: The prevalence of lead poisoning in children under the age of six years living in Lancaster County, Pennsylvania continues to be greater than the state-wide prevalence for this age group. This study aims to determine the factors that contribute to the high lead poisoning rates. METHODS: For this qualitative study, the researchers recruited a convenience sample of professionals providing healthcare and social welfare services in the county. Researchers conducted in-depth interviews with participants. The research team audio recorded, transcribed verbatim, and analyzed each interview using NVivo 12 software. RESULTS: The 16 interviewed participants identified factors that contribute to high lead poisoning rates including knowledge levels, housing status, and competing interests. Specifically, low knowledge levels, renting as opposed to home ownership, and having competing interests seemed to minimize the attention directed towards preventing lead poisoning. The experts offered recommendations to address the high lead poisoning rates including increasing lead knowledge levels of both community members and landlords, through creating and distributing health promotion material, enacting policies to empower renters, and systematically collaborating to streamline lead poisoning related information and services. CONCLUSIONS: Findings provide insights to factors that Lancaster can address to achieve a decrease in lead poisoning rates. This study provides information that can be utilized by public health professionals to develop appropriate interventions.


Assuntos
Estudos Epidemiológicos , Intoxicação por Chumbo/epidemiologia , Saúde Pública/estatística & dados numéricos , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pennsylvania/epidemiologia , Prevalência , Pesquisa Qualitativa
9.
AIDS Res Hum Retroviruses ; 34(8): 667-671, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29732907

RESUMO

Rilpivirine (RPV) and Etravirine (ETR) are approved second-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs) for HIV treatment. There is a cross-resistance HIV mutation profile between first- and second-generation NNRTI drugs. We determined the prevalence of HIV-1 drug resistance mutations (DRMs) to RPV and ETR in Botswana. A total of 168 HIV-1 polymerase gene sequences from participants failing nevirapine (NVP)- or efavirenz (EFV)-containing regimens were analyzed for DRMs using the Stanford University HIV drug resistance database. Forty-one sequences were from an adult antiretroviral therapy (ART) study, the Tshepo study, and 127 from a prevention of mother-to-child transmission (PMTCT) study, the Mashi study, all conducted in Botswana. Prevalence of RPV and ETR highest DRM in the adult ART study (n = 41) were K101E (26.2%), E138A (23.8%), and Y181C (26.2%). The PMTCT cohort's (n = 127) high prevalence mutations were Y181C (15.7%), E138A (15%), and K101E (11%). A total of 42.9% and 3.2% of patients in the adult ART study and PMTCT study, respectively, had three or more NNRTI mutations at virologic failure. We identified HIV-1 mutations conferring resistance to RPV and ETR even though they have not been used in Botswana. Of concern was the high proportion of sequences from the adult ART study that displayed multiple DRMs; as the number of NNRTI mutations increases, the level of cross-resistance increases. It is plausible that patients displaying such profiles maybe at increased risk of failing second-generation NNRTI drugs, hence, calls for genotyping in patients with prior NVP or efavirenz exposure before prescription of RPV- or ETR-containing cART.


Assuntos
Fármacos Anti-HIV/farmacologia , Farmacorresistência Viral , Infecções por HIV/virologia , HIV-1/efeitos dos fármacos , Mutação , Piridazinas/farmacologia , Rilpivirina/farmacologia , Adulto , Alcinos , Fármacos Anti-HIV/uso terapêutico , Terapia Antirretroviral de Alta Atividade/métodos , Benzoxazinas/uso terapêutico , Botsuana , Ciclopropanos , Feminino , Genótipo , Técnicas de Genotipagem , Infecções por HIV/tratamento farmacológico , Humanos , Masculino , Testes de Sensibilidade Microbiana , Nevirapina/uso terapêutico , Nitrilas , Prevalência , Pirimidinas , Falha de Tratamento , Adulto Jovem , Produtos do Gene pol do Vírus da Imunodeficiência Humana/genética
10.
J Anal Methods Chem ; 2016: 2890219, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27725893

RESUMO

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from 69.58 ± 7.20 to 113 ± 15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R2 > 0.9900) in the range of 2 to 100 ng g-1. The method also proved to be sensitive with low limits of detection (LODs) ranging from 0.48 ± 0.16 to 1.50 ± 0.50 ng g-1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants.

11.
Clin Simul Nurs ; 12(2): 51-61, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32288882

RESUMO

Simulation is commonly used in nursing education to teach clinical skills. Here, we describe the development processes, implementation, and evaluation of an epidemiology simulation used in a community and public health nursing undergraduate clinical course at the University of Pennsylvania. The simulation was designed to teach students the principles and concepts of outbreak investigation and was based on the 2003 Severe Acute Respiratory Syndrome outbreak in Toronto, Canada. The simulation places students in the role of a public health nurse in the outbreak investigation team, working in groups of five to seven students to complete analyses and make recommendations under time and information constraints. Since piloting in spring 2014, we have run the simulation three times (summer and fall 2014 and summer 2015). Student evaluations show high levels of engagement and interest and substantial increase in the skills and expertise required in an outbreak investigation. We share key lessons learned, including resources required for simulation development and delivery, revisions to the simulation format and content in response to student feedback, and transferability and sustainability of the simulation. Overall, simulation was a feasible and effective modality to teach epidemiology and should be considered in community and public health nursing courses.

12.
J Acquir Immune Defic Syndr ; 72(5): 542-545, 2016 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-26990822

RESUMO

Pill counts with calculated adherence percentages are used in many settings to monitor adherence, but can be undermined by patients discarding pills to hide nonadherence. Pill counts suggesting that >100% of prescribed doses were taken can signal "pill dumping." We defined "overadherence" among a cohort of 300 HIV-infected adolescents as having greater than one-third of pill counts with >100% adherence during a year of follow-up. Apparent overadherence was more common in those with virologic failure than in those with suppressed viral loads (33% vs 13%, χ(2) P = 0.001). Pill count adherence repeatedly >100% may identify HIV-infected adolescents at increased risk of treatment failure.


Assuntos
Comportamento do Adolescente , Fármacos Anti-HIV/administração & dosagem , Infecções por HIV/tratamento farmacológico , Cooperação do Paciente/estatística & dados numéricos , Autoadministração/estatística & dados numéricos , Adolescente , Comportamento do Adolescente/psicologia , Botsuana , Esquema de Medicação , Seguimentos , Infecções por HIV/psicologia , Humanos , Cooperação do Paciente/psicologia , Autoadministração/psicologia , Falha de Tratamento , Carga Viral
13.
J Chromatogr A ; 992(1-2): 67-74, 2003 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-12735463

RESUMO

An assay based on enzymatic hydrolysisand microdialysis sampling, micro-high-performance anion-exchange chromatography (micro-HPAEC) with electrospray ionisation mass spectrometry (ESI-MS) for the characterisation of legumes is presented. Characterisation of two bean varieties; Phaseolus mungo and P. acutifilous was based upon enzymatic hydrolysis using an endo-beta-mannanase from Aspergillus niger with subsequent analysis of the hydrolysates with HPAEC-MS. The hydrolysates were detected in the positive ionisation mode after desalting the chromatographic effluent, employing a cation-exchange membrane desalting device with water as the regenerating liquid. Mass chromatograms, acquiredafter hydrolysis of both bean samples for 12 h, showed two different profiles of hydrolysates. The P. mungo bean hydrolysate showed the presence of saccharides with a degree of polymerisation (DP) in the range of 2-6, whereas that of P. acutifilous showed only DPs of 2-5. Both bean samples had one type of DP 2, but showed different types of DPs 3, 4 and 5. Only the P. mungo sample showed the presence of DP 6. The most abundant fraction for P. mungo was DP 4, whereas that for P. acutifilous was DP 5. Tandem MS of the hydrolysates showed that the DP 2 hydrolysates observed for the samples were of the same type, having a 1,6 linkage. Also tandem MS data for DPs 3, 4, and 5 showed that similar hydrolysates were present within the same sample as well as among the two samples. The data also showed the existence of 1,6 linkages for DP 3, 4, and 5 hydrolysates. The single enzymatic hydrolysis in combination with microdialysis and HPAEC with ESI-MS proved to be sufficient and reproducible for profiling and showing the difference between the two bean samples.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cromatografia por Troca Iônica/métodos , Fabaceae/química , Espectrometria de Massas por Ionização por Electrospray/métodos , beta-Manosidase/química , Resinas de Troca Aniônica , Hidrólise , Microdiálise
14.
Curr Drug Metab ; 14(4): 392-413, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23330927

RESUMO

Polyphenols are a versatile class of compounds that represent secondary metabolites from higher plants and which are abundantly present in the human diet. Epidemiological data suggest protective effects of polyhenols in relation to cancer, cardiovascular diseases, diabetes, infectious diseases and age-related conditions. HIV/AIDS remains prevalent in many parts of the world as acute infection and as anti-retroviral drug (ARV)-managed chronic disease. Due to the nature of the human immune deficiency virus (HIV) and an increased use of ARVs many drug-resistant HIV strains have emerged and continue to do so. This makes it impossible to rely on one standard drug treatment regime. This review summarizes anti- HIV activities of polyphenols. It highlights the diversity of modes of action by which polyphenols - according to their respective compound classes - exert their activities. Additionally, this review discusses polyphenols as multi-target anti-HIV agents and provides the context of in-vivo and clinical data. Based on the presented data, a three-pronged approach for further anti-HIV drug discovery is suggested applying methods of combinatorial medicinal chemistry on the diverse and sometimes unique scaffolds of polyphenols. The latter being selected according to the approach of 'reverse pharmacology' as a creative way to place safety and other clinical consideration at the beginning of the drug discovery- and development process.


Assuntos
Fármacos Anti-HIV/uso terapêutico , Flavonoides/uso terapêutico , Infecções por HIV/tratamento farmacológico , Animais , Fármacos Anti-HIV/química , Fármacos Anti-HIV/farmacologia , Interações Medicamentosas , Flavonoides/química , Flavonoides/farmacologia , Infecções por HIV/metabolismo , HIV-1/efeitos dos fármacos , HIV-1/fisiologia , Humanos , Fenóis/farmacologia , Taninos/farmacologia
15.
Anal Chim Acta ; 730: 42-8, 2012 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-22632043

RESUMO

The determination of four potentially toxic heavy metals, arsenic, chromium, lead and nickel in twelve plant species used for the treatment of perceived HIV and AIDS-associated opportunistic infections by traditional healers in Ngamiland District in Northern Botswana, a metal mining area, was carried out using atomic absorption spectrometry. The medicinal plants; Dichrostachys cinerea, Maerua angolensis, Mimusops zeyheri, Albizia anthelmintica, Plumbago zeylanica, Combretum imberbe, Indigofera flavicans, Clerodendrum ternatum, Solanum panduriforme, Capparis tomentosa, Terminalia sericea and Maytenus senegalensis contained heavy metals in varying quantities: arsenic 0.19-0.54 µg g(-1), chromium 0.15-1.27 µg g(-1), lead 0.12-0.23 µg g(-1) and nickel 0.09-0.21 µg g(-1) of dry weight. Chromium was found to be the most abundant followed by arsenic and lead. Nickel was undetectable in nine plant species. M. senegalensis contained the largest amounts of arsenic, chromium and lead. All metals determined were below the WHO permissive maximum levels. The possible maximum weekly intakes of the heavy metals following treatment regimes were insignificant compared to the provisional tolerable weekly intake levels recommended by WHO and the Joint FAO/WHO Expert Committee on Food Additives. This suggests that heavy metal exposure to patients originating from consumption of traditional medicinal plant preparations is within non health-compromising limits.


Assuntos
Infecções Oportunistas Relacionadas com a AIDS/tratamento farmacológico , Medicinas Tradicionais Africanas , Metais Pesados/análise , Plantas Medicinais/química , Arsênio/análise , Botsuana , Cromo/análise , Poluentes Ambientais/análise , Humanos , Chumbo/análise , Mineração , Níquel/análise , Espectrofotometria Atômica
16.
Biotechnol Bioeng ; 78(7): 822-8, 2002 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-12001175

RESUMO

An on-line system based on microdialysis sampling (MD), micro-high performance anion exchange chromatography (micro-HPAEC), integrated pulsed electrochemical detection (IPED), and electrospray ionization mass spectrometry (MS) for the monitoring of on-line desalted enzymatic hydrolysates is presented. Continuous monitoring of the enzymatic degradation of dissolving pulp from Eucalyptus grandis as well as degradation of sugar cane bagasse in a 5-mL reaction vessel was achieved up to 24 h without any additional sample handling steps. Combining MD with micro-HPAEC-IPED/MS and on-line desalting of hydrolysates enabled injection (5 microL) of at least 23 samples in a study of the sequential action of hydrolytic enzymes in an unmodified environment where the enzymes and substrate were not depleted due to the perm-selectivity of the MD membrane (30 kDa cut-off). Xylanase, phenolic acid esterase and a combination of endoglucanase (EG II) with cellobiohydrolase (CBH I) resulted in the production of DP 1 after the addition of esterase, DP 2 and DP 3 after the addition of EG II and CBH I, from the dissolving pulp substrate. Similar sequential enzyme addition to sugar cane bagasse resulted in DP 1 production after the addition of esterase and DP 1, DP 2 and DP 3 production after the addition of the EG II and CBH I mixture. Combining MS on-line with micro-HPAEC-IPED proved to be a versatile and necessary tool for such a study compared to conventional methods. The mass selectivity of MS revealed complementary information, including the co-elution of saccharides as well as the presence of more than one type of DP 2 in the case of dissolving pulp and several types of DP 2 and DP 3 for sugar cane bagasse. This study demonstrates the limitation of the use of retention time alone for confirmation of the identity of saccharides especially when dealing with complex enzymatic hydrolysates. In situ sampling and sample clean-up combined with on-line desalting of the chromatographic effluent, provides a generic approach to achieve real time monitoring of enzymatic hydrolysates when they are detected by a combination of IPED and MS.


Assuntos
Celulose/química , Eucalyptus/química , Hidrolases/química , Lignina/química , Celulase/química , Cromatografia por Troca Iônica/métodos , Eletroquímica/métodos , Esterases/química , Hidrólise , Microdiálise/métodos , Extratos Vegetais/química , Hidrolisados de Proteína , Sensibilidade e Especificidade , Espectrometria de Massas por Ionização por Electrospray/métodos , Fatores de Tempo , Xilano Endo-1,3-beta-Xilosidase , Xilosidases/química
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