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1.
Sci Rep ; 12(1): 16084, 2022 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-36167891

RESUMO

Zinc deficiency impairs the antibody-mediated immune response and is common in children from lower-income countries. This study aimed to investigate the impact of different zinc supplementation regimens (7, 10 or 20 mg/day elemental zinc)-therapeutic dispersible zinc tablets (TZ), daily multiple micronutrient powder (MNP), daily preventive zinc tablets (PZ) and placebo powder (control)-and compare between baseline and endline antibody production against pathogenic Escherichia coli in Laotian children (aged 6-23 months). Fifty representative plasma samples of each treatment group were randomly selected from 512 children to determine anti-E. coli IgG antibody levels and avidity. Of the 200 children, 78.5% had zinc deficiency (plasma zinc concentration < 65 µg/dL) and 40% had anaemia before receiving zinc supplementation. aAfter receiving the TZ, MNP or PZ regimen, the plasma anti-E. coli IgG levels were significantly increased compared with baseline; the effect on the antibody level was more pronounced in children with zinc deficiency. Interestingly, there was increased anti-E. coli IgG avidity in the control and PZ groups. This study suggests that PZ might be the optimal zinc supplementation regimen to increase both the quantity and quality of antibody responses in children with zinc deficiency. Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT02428647 (NCT02428647, 29/04/2015).


Assuntos
Formação de Anticorpos , Zinco , Criança , Suplementos Nutricionais , Escherichia coli , Humanos , Imunoglobulina G , Lactente , Micronutrientes , Pós
2.
J Adv Nurs ; 78(10): 3470-3482, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35919016

RESUMO

AIM: Retaining nurses on the job is vital, and their successful retention is related to the organizational climates (OC) of healthcare settings. The purpose was to develop and test the psychometric properties of the Perceived Organizational Climate Scale (POCS). DESIGN: The methodologic research design was used by following the scale development strategies by DeVellis (2017). The conceptual framework for this study was based on the broader theoretical framework of the Competing Value Framework (CVF) of Quinn et al. (2015), the concept analysis and extensive literature review (1939-2018), and combined with the inductive qualitative data. METHODS: A two-phase study of scale construction and psychometric testing was conducted for content validation, construct validation and internal consistency reliabilities of the instrument. An expert panel validated the 4-point scale, followed by exploratory factor analysis, the known-group approach and split groups. Data were collected from (1161) registered nurses in eight general hospitals across Myanmar from August 2019 to September 2020. RESULTS: The 35 items with four essential dimensions: transformational climate, bureaucratic climate, team climate and strategic climate, explained almost 50% of the variation with all factor loading greater than .40. The internal consistency reliabilities of the instrument showed the Cronbach's alpha coefficient of .93, and the dimensions were from .82 to .85. As hypothesized, the known-group approach demonstrated that experienced nurses had higher mean scores than novices. The internal consistency reliabilities of the scale and dimensions across the splitting groups illustrated the stability. CONCLUSION: This evidence supports this instrument as having satisfactory initial psychometric properties with a comprehensive picture of OC by its essential components contributing to an inclusive understanding of this climate globally. IMPACT: This instrument can be used as an objective tool for evaluating OC as perceived by nurses in healthcare settings to inform improvements in working environments.


Assuntos
Enfermeiras e Enfermeiros , Local de Trabalho , Análise Fatorial , Humanos , Psicometria/métodos , Reprodutibilidade dos Testes , Inquéritos e Questionários
3.
Infection ; 50(3): 681-688, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35034327

RESUMO

BACKGROUND: In the Greater Mekong Subregion of Southeast Asia, Plasmodium vivax malaria is endemic and causes significant morbidity. In this study, the efficacy of chloroquine for treating uncomplicated P. vivax malaria at the eastern and western borders of Myanmar was investigated. METHODS: A total of 197 participants with microscopically confirmed P. vivax infection were enrolled from three townships of the southeastern (Thanbyuzayat and Kawthoung) and western (Kyauktaw) borders of Myanmar. Patients were treated with chloroquine according to the national malaria treatment guidelines and followed for 28 days. RESULTS: Among the 197 enrollments, 172 completed the 28-day follow-up. Twelve recurrent P. vivax infections, all occurring in the third and fourth week, were detected, resulting in an overall cumulative rate of recurrence of 4.7% [95% confidence interval (CI) 1.5-7.8]. The incidence rate of recurrence varied among the three sites. In Thanbyuzayat township, no patients had recurrent parasitemia between days 7 and 28. In contrast, Kyauktaw township had a day 28 cumulative incidence rate of recurrence of 7.2% (95% CI 0.6-13.9%) compared to 6.9% (95% CI 0.6-13.2) in Kawthoung township. CONCLUSION: While this study confirmed the relatively high clinical efficacy of chloroquine for treating P. vivax in Myanmar with modest rates of recurrent infections within 28 days of the treatment, it also revealed considerable geographical heterogeneity of chloroquine efficacy, which warrants continuous surveillance efforts.


Assuntos
Antimaláricos , Malária Vivax , Antimaláricos/uso terapêutico , Cloroquina/uso terapêutico , Humanos , Malária Vivax/tratamento farmacológico , Malária Vivax/epidemiologia , Mianmar/epidemiologia , Plasmodium vivax
4.
Trop Med Infect Dis ; 6(2)2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-34070228

RESUMO

Wound infections with drug-resistant bacteria lead to higher mortality and morbidity and increased healthcare costs. We aimed to describe the spectrum of bacterial pathogens, isolated from wound cultures in Yangon General Hospital in 2018, and their antimicrobial resistance (AMR) patterns and to understand the challenges in implementing an AMR surveillance system in Myanmar. We conducted a concurrent mixed-methods study involving analysis of surveillance data and in-depth interviews with nine key personnel involved in AMR surveillance. Of 1418 wound specimens processed, 822 (58%) were culture-positive. The most common Gram-positive bacteria were coagulase-negative staphylococci (23.3%) and Staphylococcus aureus (15.1%). Among Gram-negative bacteria, Escherichia coli (12.5%) and Pseudomonas aeruginosa (10.1%) were common. Staphylococcus aureus isolates were resistant to penicillin (98%), oxacillin (70%) and tetracycline (66%). Escherichia coli showed resistance to ampicillin (98%). Lack of dedicated and trained staff (microbiologist, technician, data entry operator), lack of computers at sentinel sites and non-uniform and non-standardized data capture formats were the major challenges in implementing AMR surveillance. These challenges need to be addressed urgently. We also recommend periodic analysis and sharing of antibiograms at every hospital to inform the treatment regimens used in wound management.

5.
J Nurs Scholarsh ; 53(4): 490-499, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33689221

RESUMO

PURPOSE: To explore nurses' perceptions of the organizational climate in general hospitals in Myanmar. DESIGN AND METHODS: Using a qualitative descriptive design, data were purposively collected from all levels of registered nurses in eight general hospitals across Myanmar during August to October 2019. Seventeen individual in-depth interviews and eight focus group discussions with 65 nurses were undertaken and analyzed using Graneheim and Lundman's qualitative content analysis. FINDINGS: Four categories of organizational climate from a Myanmar nursing context emerged: organizational uniqueness, organizational alignment, sense of empowerment, and the reinforcing organization. Organizational uniqueness included the subcategories of perception of features and orientation of the organization, whilst organizational alignment comprised the three subcategories of the values inherent in the management process, the criteria of success, and strategic emphasis. The sense of empowerment category embraced the subcategories of the perceptions of the decision making and roles of leaders or managers; the last category, the reinforcing organization, incorporated the subcategories of bonding and recognition of the organization. CONCLUSIONS: This was the first qualitative nursing study on nurses' perceptions of organizational climate in Myanmar hospitals. Participants revealed a rich source of information that needs to be considered by hospital administrators and other policymakers to enhance quality clinical care by nurses, and their overall well-being and working conditions. The emphasis on the holistic nature of this concept points to further investigations of working conditions, the lives of nurses, and management of nurses within the hospital environments in Myanmar hospitals, and can inform other countries. CLINICAL RELEVANCE: Nurses revealed a rich understanding of what an organizational climate represents or should represent, and they need to work with hospital administrators and managers to contribute to the development of positive organizational climate, which in turn should increase nurse retention and the efficacy of health care provided in hospitals.


Assuntos
Enfermeiras e Enfermeiros , Recursos Humanos de Enfermagem Hospitalar , Atitude do Pessoal de Saúde , Hospitais , Humanos , Cultura Organizacional , Pesquisa Qualitativa , Inquéritos e Questionários
6.
J Asian Nat Prod Res ; 23(9): 844-850, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32851864

RESUMO

Five compounds (1-5), including three coumarins (1-3) and two alkaloids (4,5) were isolated during the first investigation of the stem bark of Aegle marmelos (L.) Corrêa. collected in Myanmar. Their structures were determined by NMR spectra analysis. Among them, 7´-O-ethylmarmin (1) and 2-O-ethyltembamide (5) were identified as new compounds. Skimmianine (4) showed moderate cytotoxicity against a HeLa cell line, and 7´-O-ethylmarmin (1), marmin (2), and (+)-epoxyaurapten (3) displayed weak radical scavenging activity according to a DPPH scavenging assay.


Assuntos
Aegle , Células HeLa , Humanos , Estrutura Molecular , Mianmar , Extratos Vegetais
7.
Nurs Forum ; 56(1): 172-180, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33020958

RESUMO

AIM: The overarching objective of this report is to provide an updated definition of the concept of organizational climate and to strengthen its operational application. BACKGROUND: Organizational climate is one of the major contributing factors to the exodus of the nursing workforce from the profession. Extensive research has addressed the impact of "organizational climate" on the nursing workforce; yet variations in the interpretation of the concept calls for an updated definition. DESIGN: Walker and Avant's strategy was implemented. DATA SOURCE: Data were compiled from Medline and CINAHL, Google search engine, and book chapters. REVIEW METHOD: A comprehensive and detailed review of the literature was performed. Nineteen historic publications (1939-2012) and 39 healthcare-related publications (2013-2018) were included in the final review. RESULTS: The climate of an organization reflects a set of core values and behaviors that can be used to implement evidence-based leadership and management within the context of the 21st century. We have revised the definition of organizational climate to capture this context. CONCLUSION: The perception of a supportive and constructive climate in an organization propels the workforce, independent of ethnic or personal background, to a higher level of productivity and encourages loyalty and workforce stability.


Assuntos
Formação de Conceito , Atenção à Saúde/normas , Cultura Organizacional , Humanos , Liderança , Recursos Humanos/normas
8.
J Clin Microbiol ; 58(7)2020 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-32350042

RESUMO

Melioidosis is caused by Burkholderia pseudomallei and is predominantly seen in tropical regions. The clinical signs and symptoms of the disease are nonspecific and often result in misdiagnosis, failure of treatment, and poor clinical outcome. Septicemia with septic shock is the most common cause of death, with mortality rates above 40%. Bacterial culture is the gold standard for diagnosis, but it has low sensitivity and takes days to produce definitive results. Early laboratory diagnosis can help guide physicians to provide treatment specific to B. pseudomallei In our study, we adapted host gene expression signatures obtained from microarray data of B. pseudomallei-infected cases to develop a real-time PCR diagnostic test using two differentially expressed genes, AIM2 (absent in melanoma 2) and FAM26F (family with sequence similarity 26, member F). We tested blood from 33 patients with B. pseudomallei infections and 29 patients with other bacterial infections to validate the test and determine cutoff values for use in a cascading diagnostic algorithm. Differentiation of septicemic melioidosis from other sepsis cases had a sensitivity of 82%, specificity of 93%, and negative and positive predictive values (NPV and PPV) of 82% and 93%, respectively. Separation of cases likely to be melioidosis from those unlikely to be melioidosis in nonbacteremic situations showed a sensitivity of 40%, specificity of 54%, and NPV and PPV of 44% and 50%, respectively. We suggest that our AIM2 and FAM26F expression combination algorithm could be beneficial for early melioidosis diagnosis, offering a result within 24 h of admission.


Assuntos
Burkholderia pseudomallei , Melioidose , Sepse , Burkholderia pseudomallei/genética , Humanos , Melioidose/diagnóstico , Sensibilidade e Especificidade , Transcriptoma
9.
Molecules ; 24(2)2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30650546

RESUMO

Medicinal plants are a reservoir of biologically active compounds with therapeutic properties that over time have been reported and used by diverse groups of people for treatment of various diseases. This review covers 15 selected medicinal plants distributed in Myanmar, including Dalbergia cultrata, Eriosema chinense, Erythrina suberosa, Millettia pendula, Sesbania grandiflora, Tadehagi triquetrum, Andrographis echioides, Barleria cristata, Justicia gendarussa, Premna integrifolia, Vitex trifolia, Acacia pennata, Cassia auriculata, Croton oblongifolius and Glycomis pentaphylla. Investigation of the phytochemical constituents, biological and pharmacological activities of the selected medicinal plants is reported. This study aims at providing a collection of publications on the species of selected medicinal plants in Myanmar along with a critical review of the literature data. As a country, Myanmar appears to be a source of traditional drugs that have not yet been scientifically investigated. This review will be support for further investigations on the pharmacological activity of medicinal plant species in Myanmar.


Assuntos
Compostos Fitoquímicos/química , Compostos Fitoquímicos/farmacologia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Plantas Medicinais/química , Etnofarmacologia , Medicina Tradicional , Mianmar
10.
Diseases ; 6(1)2017 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-29278399

RESUMO

Myanmar is adjacent to India, Bangladesh, Thailand, Laos and China. In Myanmar, the prevalence of hepatitis B virus (HBV) infections is 6.5% and accounts for 60% of hepatocellular carcinoma. HBV has nine genotypes that have been identified by molecular genetic analysis. HBV genotypes are associated with several clinical features. We reviewed the prevalence of HBV genotypes in Myanmar and neighboring countries. We also reviewed HBV genotypes in refugees from Myanmar. HBV subgenotype C1 is predominant in Myanmar. As HBV genotype C is associated with hepatocellular carcinoma (HCC), it is important to screen for cirrhosis and HCC and to prevent their development in HBV-infected individuals of Myanmar.

11.
Parasit Vectors ; 10(1): 374, 2017 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-28778217

RESUMO

BACKGROUND: Soil-transmitted helminths (STH) are still highly prevalent in southeast Asia. The country of Myanmar has had ongoing mass drug administration (MDA) programmes since 2003 in an attempt to control STH and reduce STH-related morbidities. Whilst the MDA programmes have reported high nationwide coverage, there have been no epidemiological surveys that included measurements from adults. This paper details three cross-sectional surveys that took place over the course of a year in two villages endemic for STH and receiving MDA in lower Myanmar. RESULTS: At baseline, 27.81% of participants were infected with at least one type of STH. The most prevalent STH was Trichuris trichiura (18.12%) followed by hookworm (8.71%) and Ascaris lumbricoides (5.34%). Most infections were of low intensity, measured by eggs per gram of faeces (EPG). Gender stratification revealed that A. lumbricoides prevalence was significantly higher in females, whereas hookworm prevalence was significantly higher in males. The distribution of EPG in the study sample was highly overdispersed, suggesting that most people release few eggs whereas a few people release many eggs. Adults harbour a major proportion of the overall STH burden; 65.15% of STH infections were harboured by adults. CONCLUSIONS: STH infection remains at medium prevalence in the study villages despite past and recent MDA. Recorded prevalence of STH in school-aged children has not substantially decreased since the last monitoring and evaluation activities in Myanmar in 2013. Analyses suggest that adults are a major contributor to the total STH prevalence and EPG burden, probably perpetuating transmission.


Assuntos
Helmintíase/epidemiologia , Helmintíase/transmissão , Doenças Negligenciadas/epidemiologia , Solo/parasitologia , Adolescente , Adulto , Animais , Ascaris lumbricoides/isolamento & purificação , Criança , Pré-Escolar , Estudos Transversais , Doenças Endêmicas , Fezes/parasitologia , Feminino , Helmintíase/tratamento farmacológico , Helmintíase/parasitologia , Helmintos/efeitos dos fármacos , Helmintos/isolamento & purificação , Humanos , Masculino , Administração Massiva de Medicamentos , Mianmar/epidemiologia , Doenças Negligenciadas/tratamento farmacológico , Doenças Negligenciadas/parasitologia , Inquéritos e Questionários , Trichuris/isolamento & purificação , Adulto Jovem
12.
Nat Prod Commun ; 11(3): 353-64, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27169181

RESUMO

Medicinal plants are a vital source of medication in developing countries. In Kachin State, Northern Myanmar, the people have a long history of the use of traditional plants for medicinal purposes. This article deals with the 25 most used medicinal plants in Kachin State. They are: Drynariafortunei, Tetrastigma serrulatum, Bauhinia championii, Goniothalamus cheliensis, Juglans regia, Houttuynia cordata, Osmanthus fragrans, Pothos chinensis, Tabemaemontana coronaria, Eryngiumfoetidum, Chloranthus spicatus, Peperomia pellucida, Zanthoxylum armatum, Polygonumfagopyrum, Cymbidiumfloribundum, Amomum kravanh, Coscinium fenestratum, Solanum nigrum, Gnetum parvifolium, Desmodium triquetum, Begonia augustinec, Mappianthus iodoides, Erycibe obtusifolia, Schefflera venulosa, Holarrhena antidysenterica. The different traditional applications, the known chemical constituents and medicinal properties are reported for each plant. The efficacy of several of these plants has been supported by some scientific evidence, while other plants have to be submitted to further investigations to prove the beneficial medicinal properties attributed to them.


Assuntos
Medicina Tradicional/métodos , Fitoterapia , Plantas Medicinais/química , Humanos , Mianmar
13.
Environ Sci Technol ; 44(21): 8248-53, 2010 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-20929262

RESUMO

Ozonation is very effective in eliminating micropollutants that react fast with ozone (k > 10(3) M(-1) s(-1)), but there are also ozone-refractory (k < 10 M(-1) s(-1)) micropollutants such as X-ray contrast media, organic phosphates, and others. Yet, they are degraded upon ozonation to some extent, and this is due to (•)OH radicals generated in the reaction of ozone with organic matter in wastewater (DOM, determined as DOC). The elimination of tri-n-butyl phosphate (TnBP) and tris-2-chloroisopropyl phosphate (TCPP), added to wastewater in trace amounts, was studied as a function of the ozone dose and found to follow first-order kinetics. TnBP and TCPP concentrations are halved at ozone to DOC ratios of ∼0.25 and ∼1.0, respectively. The (•)OH rate constant of TCPP was estimated at (7 ± 2) × 10(8) M(-1) s(-1) by pulse radiolysis. Addition of 1 mg H(2)O(2)/L for increasing the (•)OH yield had very little effect. This is due to the low rate of reaction of H(2)O(2) with ozone at wastewater conditions (pH 8) that competes unfavorably with the reaction of ozone with wastewater DOC. Simulations based on the reported (Nöthe et al., ES&T 2009, 43, 5990-5995) (•)OH yield (13%) and (•)OH scavenger capacity of wastewater (3.2 × 10(4) (mgC/L)(-1) s(-1)) confirm the experimental data. Based on a typically applied molar ratio of ozone and H(2)O(2) of 2, the contribution of H(2)O(2) addition on the (•)OH yield is shown to become important only at high ozone doses.


Assuntos
Peróxido de Hidrogênio/química , Ozônio/química , Fosfatos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Radical Hidroxila , Fosfatos/análise , Água/química , Poluentes Químicos da Água/análise
14.
Chem Biodivers ; 7(3): 610-22, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20232323

RESUMO

Three new steroid saponins (3beta,25R)-spirost-5-en-3-yl 6-deoxy-alpha-L-mannopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->4)-6-deoxy-alpha-L-mannopyranosyl-(1-->3)]-beta-D-glucopyranoside (1), (3beta,22R,25R)-26-(beta-D-glucopyranosyloxy)-22-hydroxyfurost-5-en-3-yl 6-deoxy-alpha-L-mannopyranosyl-(1-->2)-[6-deoxy-alpha-L-mannopyranosyl-(1-->3)]-beta-D-glucopyranoside (3), and (3beta,22R,25R)-26-(beta-D-glucopyranosyloxy)-22-hydroxyfurost-5-en-3-yl 6-deoxy-alpha-L-mannopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->4)-6-deoxy-alpha-L-mannopyranosyl-(1-->3)]-beta-D-glucopyranoside (5), as well as the new pregnane glycoside (3beta,16beta)-3-{[6-deoxy-alpha-L-mannopyranosyl-(1-->2)-[6-deoxy-alpha-L-mannopyranosyl-(1-->3)]-beta-D-glucopyranosyl]oxy}-20-oxopregn-5-en-16-yl (4R)-5-(beta-D-glucopyranosyloxy)-4-methylpentanoate (6), were isolated from the rhizomes of Tacca integrifolia together with two known (25R) configurated steroid saponins (3beta,25R)-spirost-5-en-3-yl 6-deoxy-alpha-L-mannopyranosyl-(1-->2)-[6-deoxy-alpha-L-mannopyranosyl-(1-->3)]-beta-D-glucopyranoside (2) and (3beta,22R,25R)-26-(beta-D-glucopyranosyloxy)-22-methoxyfurost-5-en-3-yl 6-deoxy-alpha-L-mannopyranosyl-(1-->2)-[6-deoxy-alpha-L-mannopyranosyl-(1-->3)]-beta-D-glucopyranoside (4). The cytotoxic activity of the isolated compounds was evaluated in HeLa cells and showed the highest cytotoxicity value for compound 2 with an IC(50) of 1.2+/-0.4 muM. Intriguingly, while compounds 1-5 exhibited similar cytotoxic properties between 1.2+/-0.4 (2) and 4.0+/-0.6 muM (5), only compound 2 showed a significant microtubule-stabilizing activity in vitro.


Assuntos
Dioscoreaceae/química , Saponinas/química , Glicosídeos/química , Glicosídeos/isolamento & purificação , Glicosídeos/toxicidade , Células HeLa , Humanos , Espectroscopia de Ressonância Magnética , Rizoma/química , Saponinas/isolamento & purificação , Saponinas/toxicidade
15.
Water Sci Technol ; 59(8): 1479-85, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19403960

RESUMO

The rate constants of the reactions of O(3) with some typical wastewater pollutants (tributyltin, the macrolide antibiotic clarithromycin, the beta blocker metoprolol and the analgesic diclofenac) were determined and some mechanistic aspects were elucidated. Except for tributyltin compounds that react only slowly with O(3) (k=4-7 M(-1) s(-1)), the compounds react fast (k>10(4) M(-1) s(-1)) and can be eliminated at low O(3) doses. Clarithromycin reacts at its dimethylamino group and yields the corresponding N-oxide that is no longer biologically active. The nitrogen is also the major site of O(3) attack in diclofenac and in metoprolol. This gives rise to *OH radicals and these are the precursors of hydroxylated products and markedly contribute to chloride release in diclofenac.


Assuntos
Claritromicina/química , Diclofenaco/química , Metoprolol/química , Ozônio/química , Compostos de Trialquitina/química , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/química , Cinética , Estrutura Molecular , Oxirredução , Clima Tropical
16.
Environ Sci Technol ; 42(17): 6656-62, 2008 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-18800545

RESUMO

Ozonation of diclofenac in aqueous solution in the presence and absence of an *OH scavenger, tertiary butanol (t-BuOH), was studied, and the most important reaction intermediates and products were identified. The second-order O3 rate constantwas determined by competition with buten-3-ol and was found to be 6.8 x 10(5) M(-1) s(-1) at 20 degrees C. From this high rate constant, it has been concluded that O3 must initially add on the amino nitrogen. Decomposition of the adduct results in the formation of O3*- (--> *OH) and aminyl radical precursors. A free *OH yield of 30% was estimated based on the HCHO yields generated upon reaction of *OH with 0.01 M t-BuOH. Almost all diclofenac reacted when the molar ratio of O3/diclofenac was approximately 5:1 in the presence of t-BuOH and approximately 8:1 in its absence. As primary reaction products (maximum yield), diclofenac-2,5-iminoquinone (32%), 5-hydroxydiclofenac (7%), and 2,6-dichloroaniline (19%) were detected with respect to reacted diclofenac in the presence of t-BuOH. These primary products degraded into secondary ones when the O3 dose was increased. In the *OH-mediated reaction (absence of t-BuOH) small yields of 5-hydroxydiclofenac (4.5%), diclofenac-2,5-iminoquinone (2.7%), and 2,6-dichloroaniline (6%) resulted. Practically all Cl- (95%) was released in the absence of t-BuOH but only about 45% in the presence of t-BuOH at an O3/diclofenac molar ratio of 10: 1. Based on the reaction products, mechanisms that may account for the high O3 consumption during ozonation of diclofenac are suggested. For technical applications, adequate supply of O3 is needed not only to eliminate diclofenac, but also for the degradation of its potentially toxic products like diclofenac-2,5-iminoquinone and 5-hydroxydiclofenac.


Assuntos
Diclofenaco/química , Ozônio/química , Água/química , Cinética , Oxirredução , Soluções
18.
Chemosphere ; 65(1): 17-23, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16631229

RESUMO

Macrolide antibiotics are widely used (in the order of 1g per person per year). They pass the body largely unchanged and are also not degraded in wastewater treatment plants. With not too much effort, they may be eliminated from their effluents by ozonation. The macrolide antibiotics have all a dimethylamino group at one of the carbohydrate residues in common. This functional group is the target of the ozone reaction, and clarithromycin has been selected here for a more detailed study. Since only the free amine reacts with ozone, the rate of reaction is pH dependent (at pH 7: k = 4 x 10(4) M(-1) s(-1)). In analogy to the ozonolysis of trimethylamine, the main reaction is a transfer of an O-atom yielding the N-oxide (identified by HPLC/MS-MS). A minor product (10%, based on formaldehyde yields) is demethylated clarithromycin (identified by HPLC/MS-MS). The dimethylamino group is thought to be essential for the binding of the macrolide antibiotics to their target. As a consequence, chemical changes of this functional group, notably the formation of the N-oxide that is no longer a proton acceptor, inactivates these drugs as assayed by the suppression of the growth of Pseudomonas putida. This is most important for wastewater treatment, as mineralization of clarithromycin by ozone would require 100 times as much ozone.


Assuntos
Antibacterianos/análise , Claritromicina/análise , Ozônio/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Antibacterianos/química , Claritromicina/química , Cinética , Estrutura Molecular , Oxirredução , Pseudomonas putida/efeitos dos fármacos
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