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1.
Int Health ; 2024 Mar 29.
Article in English | MEDLINE | ID: mdl-38551313

ABSTRACT

BACKGROUND: Pre-exposure prophylaxis (PrEP) is effective for human immunodeficiency virus (HIV) prevention in risk groups. We assessed PrEP uptake and 12-month retention among men who have sex with men (MSM) and transgender women (TGW) in Myanmar during the coronavirus disease 2019 pandemic and a political crisis. METHODS: Using prospectively collected data, we assessed the proportion of persons eligible, initiated and retained 12 months on PrEP. We calculated HIV and syphilis incidence among those initiated on PrEP. Predictors of compliance to scheduled visits were assessed with fractional logistic regression. RESULTS: Among 652 persons screened between July and December 2020, 85.3% were eligible and 38.8% initiated PrEP. The daily pill burden was the main reason (86.5%) for refusing PrEP. A history of HIV post-exposure prophylaxis (PEP) and having an HIV-positive partner not on anti-retroviral therapy (ART) was associated with PrEP uptake (p<0.05). The 12-month retention among those initiating PrEP was 43.0%. Age ≥25 y, a history of PEP and having an HIV-positive partner not on ART predicted better compliance with scheduled visits (p<0.05). HIV incidence among PrEP initiators was 3.1 per 100 person-years (95% confidence interval [CI] 1.3 to 7.4) and syphilis incidence was 17.6 per 100 person-years (95% CI 12.3 to 25.1). CONCLUSIONS: A PrEP program for MSM and TGW in Myanmar was implemented successfully under difficult circumstances. Alternative strategies are needed addressing PrEP uptake and retention.

2.
PLoS One ; 18(4): e0272673, 2023.
Article in English | MEDLINE | ID: mdl-37053171

ABSTRACT

INTRODUCTION: HIV viral load (VL) testing in resource-limited settings is often centralised, limiting access. In Myanmar, we assessed outcomes according to VL access and the VL cascade (case management after a first high VL result) before and after near point-of-care (POC) VL was introduced. METHODS: Routine programme data from people living with HIV (PLHIV) on antiretroviral therapy (ART) were used. We assessed the odds of getting a VL test done by year. Attrition and mortality two years after ART initiation were compared between three groups of PLHIV with different access to VL testing using Kaplan-Meier analysis. We compared VL cascades in those with a first VL result before and after near POC VL testing became available. With logistic regression, predictors of confirmed virological failure after a first high VL in the POC era were explored. RESULTS: Among 4291 PLHIV who started ART between July 2009 and June 2018, 794 (18.5%) became eligible for VL testing when it was not available, 2388 (55.7%) when centralised laboratory-based VL testing was available, and 1109 (25.8%) when near POC VL testing was available. Between 2010 and 2019, the odds of getting a VL test among those eligible increased with each year (OR: 5.21 [95% CI: 4.95-5.48]). Attrition and mortality were not different in the three groups. When comparing PLHIV with a first VL result before and after implementation of the near POC VL testing, in the latter, more had a first VL test (92% versus 15%, p<0.001), less had a first high VL result (5% versus 14%, p<0.001), and more had confirmed virological failure (67% versus 47%, p = 0.013). Having a first VL ≥5000 copies/mL after near POC implementation was associated with confirmed virological failure (adjusted OR: 2.61 [95% CI: 1.02-6.65]). CONCLUSION: Near POC VL testing enabled rapid increase of VL coverage and a well-managed VL cascade in Myanmar.


Subject(s)
Anti-HIV Agents , HIV Infections , Humans , Point-of-Care Systems , Viral Load , Myanmar/epidemiology , HIV Infections/diagnosis , HIV Infections/drug therapy , Serologic Tests , Point-of-Care Testing , Anti-HIV Agents/therapeutic use
4.
Lancet Infect Dis ; 21(11): 1579-1589, 2021 11.
Article in English | MEDLINE | ID: mdl-34147154

ABSTRACT

BACKGROUND: To contain multidrug-resistant Plasmodium falciparum, malaria elimination in the Greater Mekong subregion needs to be accelerated while current antimalarials remain effective. We evaluated the safety, effectiveness, and potential resistance selection of dihydroartemisinin-piperaquine mass drug administration (MDA) in a region with artemisinin resistance in Myanmar. METHODS: We did a cluster-randomised controlled trial in rural community clusters in Kayin (Karen) state in southeast Myanmar. Malaria prevalence was assessed using ultrasensitive quantitative PCR (uPCR) in villages that were operationally suitable for MDA (villages with community willingness, no other malaria control campaigns, and a population of 50-1200). Villages were eligible to participate if the prevalence of malaria (all species) in adults was greater than 30% or P falciparum prevalence was greater than 10% (or both). Contiguous villages were combined into clusters. Eligible clusters were paired based on P falciparum prevalence (estimates within 10%) and proximity. Community health workers provided routine malaria case management and distributed long-lasting insecticidal bed-nets (LLINs) in all clusters. Randomisation of clusters (1:1) to the MDA intervention group or control group was by public coin-flip. Group allocations were not concealed. Three MDA rounds (3 days of supervised dihydroartemisinin-piperaquine [target total dose 7 mg/kg dihydroartemisinin and 55 mg/kg piperaquine] and single low-dose primaquine [target dose 0·25 mg base per kg]) were delivered to intervention clusters. Parasitaemia prevalence was assessed at 3, 5, 10, 15, 21, 27, and 33 months. The primary outcomes were P falciparum prevalence at months 3 and 10. All clusters were included in the primary analysis. Adverse events were monitored from the first MDA dose until 1 month after the final dose, or until resolution of any adverse event occurring during follow-up. This trial is registered with ClinicalTrials.gov, NCT01872702. FINDINGS: Baseline uPCR malaria surveys were done in January, 2015, in 43 villages that were operationally suitable for MDA (2671 individuals). 18 villages met the eligibility criteria. Three villages in close proximity were combined into one cluster because a border between them could not be defined. This gave a total of 16 clusters in eight pairs. In the intervention clusters, MDA was delivered from March 4 to March 17, from March 30 to April 10, and from April 27 to May 10, 2015. The weighted mean absolute difference in P falciparum prevalence in the MDA group relative to the control group was -10·6% (95% CI -15·1 to -6·1; p=0·0008) at month 3 and -4·5% (-10·9 to 1·9; p=0·14) at month 10. At month 3, the weighted P falciparum prevalence was 1·4% (0·6 to 3·6; 12 of 747) in the MDA group and 10·6% (7·0 to 15·6; 56 of 485) in the control group. Corresponding prevalences at month 10 were 3·2% (1·5 to 6·8; 34 of 1013) and 5·8% (2·5 to 12·9; 33 of 515). Adverse events were reported for 151 (3·6%) of 4173 treated individuals. The most common adverse events were dizziness (n=109) and rash or itching (n=20). No treatment-related deaths occurred. INTERPRETATION: In this low-transmission setting, the substantial reduction in P falciparum prevalence resulting from support of community case management was accelerated by MDA. In addition to supporting community health worker case management and LLIN distribution, malaria elimination programmes should consider using MDA to reduce P falciparum prevalence rapidly in foci of higher transmission. FUNDING: The Global Fund to Fight AIDS, Tuberculosis and Malaria.


Subject(s)
Artemisinins/pharmacology , Artemisinins/therapeutic use , Drug Resistance , Malaria, Falciparum/drug therapy , Malaria, Falciparum/parasitology , Quinolines/therapeutic use , Adolescent , Adult , Antimalarials/administration & dosage , Antimalarials/therapeutic use , Artemisinins/administration & dosage , Child , Cluster Analysis , Disease Eradication , Drug Therapy, Combination , Female , Humans , Malaria, Falciparum/epidemiology , Male , Mass Drug Administration , Myanmar/epidemiology , Primaquine/administration & dosage , Primaquine/therapeutic use , Quinolines/administration & dosage , Young Adult
5.
BMC Infect Dis ; 21(1): 375, 2021 Apr 21.
Article in English | MEDLINE | ID: mdl-33882845

ABSTRACT

BACKGROUND: Cryptococcal meningitis (CM) is a common HIV-associated opportunistic-infection worldwide. Existing literature focusses on hospital-based outcomes of induction treatment. This paper reviews outpatient management in integrated primary care clinics in Yangon. METHOD: This retrospective case note review analyses a Myanmar HIV-positive patient cohort managed using ambulatory induction-phase treatment with intravenous amphotericin-B-deoxycholate (0.7-1.0 mg/kg) and oral fluconazole (800 mg orally/day). RESULTS: Seventy-six patients were diagnosed between 2010 and 2017. The median age of patients diagnosed was 35 years, 63% were male and 33 (45%) were on concurrent treatment for tuberculosis. The median CD4 count was 60 at the time of diagnosis. Amphotericin-B-deoxycholate infusions precipitated 56 episodes of toxicity, namely hypokalaemia, nephrotoxicity, anaemia, febrile reactions, phlebitis, observed in 44 patients (58%). One-year survival (86%) was higher than existing hospital-based treatment studies. CONCLUSION: Ambulation of patients in this cohort saved 1029 hospital bed days and had better survival outcomes when compared to hospital-based studies in other resource constrained settings.


Subject(s)
AIDS-Related Opportunistic Infections/complications , Amphotericin B/administration & dosage , Antifungal Agents/administration & dosage , Cryptococcus neoformans/immunology , Deoxycholic Acid/administration & dosage , Fluconazole/administration & dosage , HIV , Meningitis, Cryptococcal/complications , Meningitis, Cryptococcal/drug therapy , Primary Health Care , AIDS-Related Opportunistic Infections/epidemiology , AIDS-Related Opportunistic Infections/virology , Administration, Intravenous , Administration, Oral , Adolescent , Adult , Amphotericin B/adverse effects , Antifungal Agents/adverse effects , Cryptococcus neoformans/isolation & purification , Deoxycholic Acid/adverse effects , Drug Combinations , Drug Therapy, Combination , Female , Fluconazole/adverse effects , Humans , Male , Meningitis, Cryptococcal/epidemiology , Meningitis, Cryptococcal/microbiology , Middle Aged , Myanmar/epidemiology , Phlebitis/chemically induced , Retrospective Studies , Treatment Outcome , Young Adult
6.
Trans R Soc Trop Med Hyg ; 115(8): 914-921, 2021 08 02.
Article in English | MEDLINE | ID: mdl-33681986

ABSTRACT

BACKGROUND: Lower respiratory infections constitute a major disease burden worldwide. Treatment is usually empiric and targeted towards typical bacterial pathogens. Understanding the prevalence of pathogens not covered by empirical treatment is important to improve diagnostic and treatment algorithms. METHODS: A prospective observational study in peri-urban communities of Yangon, Myanmar was conducted between July 2018 and April 2019. Sputum specimens of 299 adults presenting with fever and productive cough were tested for Mycobacterium tuberculosis (microscopy and GeneXpert MTB/RIF [Mycobacterium tuberculosis/resistance to rifampicin]) and Burkholderia pseudomallei (Active Melioidosis Detect Lateral Flow Assay and culture). Nasopharyngeal swabs underwent respiratory virus (influenza A, B, respiratory syncytial virus) polymerase chain reaction testing. RESULTS: Among 299 patients, 32% (95% confidence interval [CI] 26 to 37) were diagnosed with tuberculosis (TB), including 9 rifampicin-resistant cases. TB patients presented with a longer duration of fever (median 14 d) and productive cough (median 30 d) than non-TB patients (median fever duration 6 d, cough 7 d). One case of melioidosis pneumonia was detected by rapid test and confirmed by culture. Respiratory viruses were detected in 16% (95% CI 12 to 21) of patients. CONCLUSIONS: TB was very common in this population, suggesting that microscopy and GeneXpert MTB/RIF on all sputum samples should be routinely included in diagnostic algorithms for fever and cough. Melioidosis was uncommon in this population.


Subject(s)
Melioidosis , Mycobacterium tuberculosis , Respiratory Tract Infections , Tuberculosis, Pulmonary , Tuberculosis , Adult , Drug Resistance, Bacterial , Humans , Melioidosis/diagnosis , Melioidosis/drug therapy , Melioidosis/epidemiology , Myanmar/epidemiology , Primary Health Care , Respiratory Tract Infections/diagnosis , Respiratory Tract Infections/drug therapy , Respiratory Tract Infections/epidemiology , Sensitivity and Specificity , Sputum , Tuberculosis, Pulmonary/diagnosis , Tuberculosis, Pulmonary/drug therapy , Tuberculosis, Pulmonary/epidemiology
7.
Am J Trop Med Hyg ; 104(3): 1022-1033, 2021 01 11.
Article in English | MEDLINE | ID: mdl-33432906

ABSTRACT

Epidemiology, ventilator management, and outcome in patients receiving invasive ventilation in intensive care units (ICUs) in middle-income countries are largely unknown. PRactice of VENTilation in Middle-income Countries is an international multicenter 4-week observational study of invasively ventilated adult patients in 54 ICUs from 10 Asian countries conducted in 2017/18. Study outcomes included major ventilator settings (including tidal volume [V T ] and positive end-expiratory pressure [PEEP]); the proportion of patients at risk for acute respiratory distress syndrome (ARDS), according to the lung injury prediction score (LIPS), or with ARDS; the incidence of pulmonary complications; and ICU mortality. In 1,315 patients included, median V T was similar in patients with LIPS < 4 and patients with LIPS ≥ 4, but lower in patients with ARDS (7.90 [6.8-8.9], 8.0 [6.8-9.2], and 7.0 [5.8-8.4] mL/kg Predicted body weight; P = 0.0001). Median PEEP was similar in patients with LIPS < 4 and LIPS ≥ 4, but higher in patients with ARDS (five [5-7], five [5-8], and 10 [5-12] cmH2O; P < 0.0001). The proportions of patients with LIPS ≥ 4 or with ARDS were 68% (95% CI: 66-71) and 7% (95% CI: 6-8), respectively. Pulmonary complications increased stepwise from patients with LIPS < 4 to patients with LIPS ≥ 4 and patients with ARDS (19%, 21%, and 38% respectively; P = 0.0002), with a similar trend in ICU mortality (17%, 34%, and 45% respectively; P < 0.0001). The capacity of the LIPS to predict development of ARDS was poor (receiver operating characteristic [ROC] area under the curve [AUC] of 0.62, 95% CI: 0.54-0.70). In Asian middle-income countries, where two-thirds of ventilated patients are at risk for ARDS according to the LIPS and pulmonary complications are frequent, setting of V T is globally in line with current recommendations.


Subject(s)
Developing Countries/statistics & numerical data , Epidemiological Monitoring , Intensive Care Units/statistics & numerical data , Respiration, Artificial/methods , Respiration, Artificial/statistics & numerical data , Respiratory Distress Syndrome/therapy , Adult , Aged , Asia/epidemiology , Female , Humans , Male , Middle Aged , Prospective Studies , Respiratory Distress Syndrome/epidemiology , Treatment Outcome
8.
Int J Infect Dis ; 103: 494-501, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33310022

ABSTRACT

BACKGROUND: Little research has been published on the prevalence of rickettsial infections in Myanmar. This study determined the seroprevalence of immunoglobulin G (IgG) antibodies to rickettsial species in different regions of Myanmar. METHODS: Seven hundred leftover blood samples from patients of all ages in primary care clinics and hospitals in seven regions of Myanmar were collected. Samples were screened for scrub typhus group (STG), typhus group (TG) and spotted fever group (SFG) IgG antibodies using enzyme-linked immunosorbent assays (ELISA). Immunofluorescence assays were performed for the same rickettsial groups to confirm seropositivity if ELISA optical density ≥0.5. RESULTS: Overall IgG seroprevalence was 19% [95% confidence interval (CI) 16-22%] for STG, 5% (95% CI 3-7%) for TG and 3% (95% CI: 2-5%) for SFG. The seroprevalence of STG was particularly high in northern and central Myanmar (59% and 19-33%, respectively). Increasing age was associated with higher odds of STG and TG seropositivity [per 10-year increase, adjusted odds ratio estimate 1.68 (p < 0.01) and 1.24 (p = 0.03), respectively]. CONCLUSION: Rickettsial infections are widespread in Myanmar, with particularly high seroprevalence of STG IgG antibodies in central and northern regions. Healthcare workers should consider rickettsial infections as common causes of fever in Myanmar.


Subject(s)
Rickettsia Infections/epidemiology , Adult , Antibodies, Bacterial/blood , Enzyme-Linked Immunosorbent Assay , Female , Humans , Immunoglobulin G/blood , Male , Middle Aged , Myanmar/epidemiology , Rickettsia Infections/immunology , Seroepidemiologic Studies
9.
Lancet Glob Health ; 7(1): e119-e131, 2019 Jan.
Article in English | MEDLINE | ID: mdl-30554748

ABSTRACT

BACKGROUND: In southeast Asia, antibiotic prescription in febrile patients attending primary care is common, and a probable contributor to the high burden of antimicrobial resistance. The objective of this trial was to explore whether C-reactive protein (CRP) testing at point of care could rationalise antibiotic prescription in primary care, comparing two proposed thresholds to classify CRP concentrations as low or high to guide antibiotic treatment. METHODS: We did a multicentre, open-label, randomised, controlled trial in participants aged at least 1 year with a documented fever or a chief complaint of fever (regardless of previous antibiotic intake and comorbidities other than malignancies) recruited from six public primary care units in Thailand and three primary care clinics and one outpatient department in Myanmar. Individuals were randomly assigned using a computer-based randomisation system at a ratio of 1:1:1 to either the control group or one of two CRP testing groups, which used thresholds of 20 mg/L (group A) or 40 mg/L CRP (group B) to guide antibiotic prescription. Health-care providers were masked to allocation between the two intervention groups but not to the control group. The primary outcome was the prescription of any antibiotic from day 0 to day 5 and the proportion of patients who were prescribed an antibiotic when CRP concentrations were above and below the 20 mg/L or 40 mg/L thresholds. The primary outcome was analysed in the intention-to-treat and per-protocol populations. The trial is registered with ClinicalTrials.gov, number NCT02758821, and is now completed. FINDINGS: Between June 8, 2016, and Aug 25, 2017, we recruited 2410 patients, of whom 803 patients were randomly assigned to CRP group A, 800 to CRP group B, and 807 to the control group. 598 patients in CRP group A, 593 in CRP group B, and 767 in the control group had follow-up data for both day 5 and day 14 and had been prescribed antibiotics (or not) in accordance with test results (per-protocol population). During the trial, 318 (39%) of 807 patients in the control group were prescribed an antibiotic by day 5, compared with 290 (36%) of 803 patients in CRP group A and 275 (34%) of 800 in CRP group B. The adjusted odds ratio (aOR) of 0·80 (95% CI 0·65-0·98) and risk difference of -5·0 percentage points (95% CI -9·7 to -0·3) between group B and the control group were significant, although lower than anticipated, whereas the reduction in prescribing in group A compared with the control group was not significant (aOR 0·86 [0·70-1·06]; risk difference -3·3 percentage points [-8·0 to 1·4]). Patients with high CRP concentrations in both intervention groups were more likely to be prescribed an antibiotic than in the control group (CRP ≥20 mg/L: group A vs control group, p<0·0001; CRP ≥40 mg/L: group B vs control group, p<0·0001), and those with low CRP concentrations were more likely to have an antibiotic withheld (CRP <20 mg/L: group A vs control group, p<0·0001; CRP <40 mg/L: group B vs control group, p<0·0001). 24 serious adverse events were recorded, consisting of 23 hospital admissions and one death, which occurred in CRP group A. Only one serious adverse event was thought to be possibly related to the study (a hospital admission in CRP group A). INTERPRETATION: In febrile patients attending primary care, testing for CRP at point of care with a threshold of 40 mg/L resulted in a modest but significant reduction in antibiotic prescribing, with patients with high CRP being more likely to be prescribed an antibiotic, and no evidence of a difference in clinical outcomes. This study extends the evidence base from lower-income settings supporting the use of CRP tests to rationalise antibiotic use in primary care patients with an acute febrile illness. A key limitation of this study is the individual rather than cluster randomised study design which might have resulted in contamination between the study groups, reducing the effect size of the intervention. FUNDING: Wellcome Trust Institutional Strategic Support Fund grant (105605/Z/14/Z) and Foundation for Innovative New Diagnostics (FIND) funding from the Australian Government.


Subject(s)
Anti-Bacterial Agents/therapeutic use , C-Reactive Protein/analysis , Fever/drug therapy , Point-of-Care Testing , Prescriptions/statistics & numerical data , Primary Health Care/statistics & numerical data , Adolescent , Adult , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Myanmar , Thailand , Young Adult
10.
BMJ Open ; 8(4): e020841, 2018 04 28.
Article in English | MEDLINE | ID: mdl-29705765

ABSTRACT

INTRODUCTION: Current evidence on epidemiology and outcomes of invasively mechanically ventilated intensive care unit (ICU) patients is predominantly gathered in resource-rich settings. Patient casemix and patterns of critical illnesses, and probably also ventilation practices are likely to be different in resource-limited settings. We aim to investigate the epidemiological characteristics, ventilation practices and clinical outcomes of patients receiving mechanical ventilation in ICUs in Asia. METHODS AND ANALYSIS: PRoVENT-iMIC (study of PRactice of VENTilation in Middle-Income Countries) is an international multicentre observational study to be undertaken in approximately 60 ICUs in 11 Asian countries. Consecutive patients aged 18 years or older who are receiving invasive ventilation in participating ICUs during a predefined 28-day period are to be enrolled, with a daily follow-up of 7 days. The primary outcome is ventilatory management (including tidal volume expressed as mL/kg predicted body weight and positive end-expiratory pressure expressed as cm H2O) during the first 3 days of mechanical ventilation-compared between patients at no risk for acute respiratory distress syndrome (ARDS), patients at risk for ARDS and in patients with ARDS (in case the diagnosis of ARDS can be made on admission). Secondary outcomes include occurrence of pulmonary complications and all-cause ICU mortality. ETHICS AND DISSEMINATION: PRoVENT-iMIC will be the first international study that prospectively assesses ventilation practices, outcomes and epidemiology of invasively ventilated patients in ICUs in Asia. The results of this large study, to be disseminated through conference presentations and publications in international peer-reviewed journals, are of ultimate importance when designing trials of invasive ventilation in resource-limited ICUs. Access to source data will be made available through national or international anonymised datasets on request and after agreement of the PRoVENT-iMIC steering committee. TRIAL REGISTRATION NUMBER: NCT03188770; Pre-results.


Subject(s)
Intensive Care Units , Adolescent , Adult , Asia , Developing Countries , Humans , Multicenter Studies as Topic , Observational Studies as Topic , Prospective Studies , Respiratory Distress Syndrome , Treatment Outcome
11.
New Phytol ; 178(3): 515-31, 2008.
Article in English | MEDLINE | ID: mdl-18298431

ABSTRACT

* Here, cytokinin-induced nitric oxide (NO) biosynthesis and cytokinin responses were investigated in Arabidopsis thaliana wild type and mutants defective in NO biosynthesis or cytokinin signaling components. * NO release from seedlings was quantified by a fluorometric method and, by microscopy, observed NO biosynthesis as fluorescence increase of DAR-4M AM (diaminorhodamine 4M acetoxymethyl ester) in different tissues. * Atnoa1 seedlings were indistinguishable in NO tissue distribution pattern and morphological responses, induced by zeatin, from wild-type seedlings. Wild-type and nia1,2 seedlings, lacking nitrate reductase (NR), responded to zeatin with an increase within 3 min in NO biosynthesis so that NR does not seem relevant for rapid NO induction, which was mediated by an unknown 2-(2-aminoethyl)2-thiopseudourea (AET)-sensitive enzyme and was quenched by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-1-oxy-3-oxide (PTIO). Long-term morphological responses to zeatin were severely altered and NO biosynthesis was increased in nia1,2 seedlings. As cytokinin signaling mutants we used the single-receptor knockout cre1/ahk4, three double-receptor knockouts (ahk2,3, ahk2,4, ahk3,4) and triple-knockout ahp1,2,3 plants. All cytokinin-signaling mutants showed aberrant tissue patterns of NO accumulation in response to zeatin and altered morphological responses to zeatin. * Because aberrant NO biosynthesis correlated with aberrant morphological responses to zeatin the hypothesis was put forward that NO is an intermediate in cytokinin signaling.


Subject(s)
Arabidopsis/metabolism , Gene Expression Regulation, Plant/drug effects , Nitric Oxide/biosynthesis , Signal Transduction/genetics , Zeatin/pharmacology , Arabidopsis/cytology , Arabidopsis/genetics , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Cyclic N-Oxides/pharmacology , Dose-Response Relationship, Drug , Imidazoles/pharmacology , Mutation , Nitric Oxide Synthase/genetics , Nitric Oxide Synthase/metabolism , Plant Leaves/metabolism , Plant Roots/metabolism , Seedlings
12.
Plant Cell Physiol ; 47(3): 346-54, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16415068

ABSTRACT

In this study, we examined the regulation by putrescine, spermidine and spermine of nitric oxide (NO) biosynthesis in Arabidopsis thaliana seedlings. Using a fluorimetric method employing the cell-impermeable NO-binding dye diaminorhodamine-4M (DAR-4M), we observed that the polyamines (PAs) spermidine and spermine greatly increased NO release in the seedlings, whereas arginine and putrescine had little or no effect. Spermine, the most active PA, stimulated NO release with no apparent lag phase. The response was quenched by addition of 2-aminoethyl-2-thiopseudourea (AET), an inhibitor of the animal nitric oxide synthase (NOS) and plant NO biosynthesis, and by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-1-oxy-3-oxide (PTIO), an NO scavenger. By fluorescence microscopy, using the cell-permeable NO-binding dye diaminorhodamine-4M acetoxymethyl ester (DAR-4M AM), we observed that PAs induced NO biosynthesis in specific tissues in Arabidopsis seedlings. Spermine and spermidine increased NO biosynthesis in the elongation zone of the Arabidopsis root tip and in primary leaves, especially in the veins and trichomes, while in cotyledons little or no effect of PAs beyond the endogenous levels of NO-induced fluorescence was observed. We conclude that PAs induce NO biosynthesis in plants.


Subject(s)
Arabidopsis/drug effects , Arabidopsis/metabolism , Nitric Oxide/biosynthesis , Polyamines/pharmacology , Seedlings/drug effects , Seedlings/metabolism , Arginine/pharmacology , Cyclic N-Oxides/pharmacology , Fluorescence , Imidazoles/pharmacology , Microscopy, Fluorescence , Nitric Oxide/antagonists & inhibitors , Nitric Oxide/metabolism , Plant Leaves/cytology , Plant Leaves/drug effects , Putrescine/pharmacology , Rhodamines/pharmacology , Spermine/pharmacology , beta-Aminoethyl Isothiourea/pharmacology
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