Found 7388 matches for
Fearing that drug resistant malaria will reach Africa, Prof François Nosten and his team are among those scientists who are scrambling to stop it while they still can. Drug resistance to artemisinin has been steadily increasing in Southeast Asia. Having emerged in Cambodia in 2007, it since has been recorded in Thailand, Vietnam and Myanmar. Artemisinin is the last remaining effective drug against the resistant falciparum strain, and there are no suitable replacements yet.
BackgroundThe ownership status of individual-level health data affects the manner in which it is used. In this paper we analyze two competing models of the ownership status of the data discussed in the literature recently: private ownership and public ownership.Main bodyIn this paper we describe the limitations of these two models of data ownership with respect to individual-level health data, in particular in terms of ethical principles of justice and autonomy, risk mitigation, as well as technological, economic, and conceptual issues. We argue that undifferentiated application of neither private ownership nor public ownership will allow us to resolve all the problems associated with effective, equitable, and ethical use of data. We suggest that, instead of focusing on data ownership, we should focus on the institutional and procedural aspects of data governance, such as using Data Access Committees (DACs) or equivalent managed access processes, which can balance the elements of these two ownership frameworks.ConclusionUndifferentiated application of the ownership concept (private or public) is not helpful in resolving problems associated with sharing individual-level health data. DACs or equivalent managed access processes should be an integral part of data governance. They can approve or disapprove data access requests after considering the potential benefits and harms to data subjects, their communities, primary researchers, and the wider society.
The prognostic and diagnostic value of intraleukocytic malaria pigment in patients with severe falciparum malaria.
Severe falciparum malaria is a major cause of death in tropical countries, particularly in African children. Rapid and accurate diagnosis and prognostic assessment are critical to clinical management. In 6027 prospectively studied patients diagnosed with severe malaria we assess the prognostic value of peripheral blood film counts of malaria pigment containing polymorphonuclear leukocytes (PMNs) and monocytes. We combine these results with previously published data and show, in an individual patient data meta-analysis (n = 32,035), that the proportion of pigment containing PMNs is predictive of in-hospital mortality. In African children the proportion of pigment containing PMNs helps distinguish severe malaria from other life-threatening febrile illnesses, and it adds to the prognostic assessment from simple bedside examination, and to the conventional malaria parasite count. Microscopy assessment of pigment containing PMNs is simple and rapid, and should be performed in all patients hospitalised with suspected severe malaria.
The utility of an AMR dictionary as an educational tool to improve public understanding of antimicrobial resistance
Background: Communicating about antimicrobial resistance (AMR) to the public is challenging. Methods: We developed a dictionary of terms commonly used to communicate about AMR. For each term, we developed learning points to explain AMR and related concepts in plain language. We conducted a pilot evaluation in 374 high school students in Ubon Ratchathani, Thailand. In three 50-minute sessions, students were asked to answer five true/false questions using a paper-based questionnaire. The first session assessed their understanding of AMR at baseline, the second after searching the internet, and the third after the provision of the printed AMR dictionary and its web address. Results: We developed the AMR dictionary as a web-based application (www.amrdictionary.net). The Thai version of the AMR dictionary included 35 terms and associated learning points, seven figures displaying posters promoting AMR awareness in Thailand, and 66 recommended online videos. In the pretest, the proportion of correct responses to each question ranged from 10% to 57%; 10% of the students correctly answered that antibiotics cannot kill viruses and 57% correctly answered that unnecessary use of antibiotics makes them ineffective. After the internet searches, the proportions of correct answers increased, ranging from 62% to 89% (all p<0.001). After providing the AMR dictionary, the proportions of correct answers increased further, ranging from 79% to 89% for three questions (p<0.001), and did not change for one question (p=0.15). Correct responses as to whether taking antibiotics often has side-effects such as diarrhoea reduced from 85% to 74% (p<0.001). The dictionary was revised based on the findings and comments received. Conclusions: Understanding of AMR among Thai high school students is limited. The AMR dictionary can be a useful supportive tool to increase awareness and improve understanding of AMR. Our findings support the need to evaluate the effectiveness of communication tools in the real-world setting.
The standard methodology for titrating dengue viruses, the plaque assay, is slow, time consuming and relatively expensive. Other methods require machinery that may not be routinely accessible to all researchers, particularly those in developing nations. We therefore sought to develop a rapid, simplified semiquantitative polymerase chain reaction (PCR) methodology based on the use of a template mimic. In particular, it was desired that the mimic should be applicable for use a DNA template to avoid the requirement for producing an in vitro RNA transcript. A 511 base pair fragment of the capsid-PrM junction of dengue serotype 4 was cloned into pGEM-T Easy vector and subjected to splicing overlap extension-PCR to generate a 160 base pair deletion. The deleted plasmid mimic competed competitively against the parent plasmid as well as the first strand cDNA of all four dengue viruses. The primers used are specific for the dengue virus, and no product was seen with first strand cDNA from a closely related flavivirus, Japanese encephalitis virus. Under the conditions used, accurate quantitation of the dengue viruses in the range of 10(3) to 10(6) pfu can be achieved in a single day, as opposed to the 7 days required for conventional plaque assay.
cDNA-AFLP analysis of differential gene expression in human hepatoma cells (HepG2) upon dengue virus infection.
In infectious diseases, the disease pathogenesis is the outcome of the interaction between the genome of the host and the genome of the pathogen. Despite the wide distribution of dengue infections in the world, and the large number of annual infections, few studies have investigated how the dengue genome alters the global transcriptional profile of the host cell. To investigate alterations in the liver cell transcriptome in response to dengue virus infection, liver cells (HepG2) were infected with dengue serotype 2 at MOI 5 and at 3 days post-infection RNA extracted and analyzed by cDNA-AFLP in parallel with mock-infected cells. From 73 primer combinations over 5,000 transcription-derived fragments (TDFs) were observed, of which approximately 10% were regulated differentially in response to infection. Sixty-five TDFs were subsequently cloned and sequenced and 27 unique gene transcripts identified. Semi-quantitative reverse transcription (RT)-PCR was used to validate the expression of 12 of these genes and 10 transcripts (CK2, KIAA509, HSP70, AK3L, NIPA, PHIP, RiboS4, JEM-1, MALT1, and HSI12044) were confirmed to be differentially regulated, with four transcripts (HSP70, NIPA, RiboS4, and JEM-1) showing a greater than twofold regulation. These results suggest that the expression of a large number of genes is altered in response to dengue virus infection of liver cells, and that cDNA-AFLP is a useful tool for obtaining information on both characterized and as yet uncharacterized transcripts whose expression is altered during the infection process.
Similarities and differences in the biogenesis, processing and lysosomal targeting between zebrafish and human pro-Cathepsin D: functional implications.
The lysosomal protease Cathepsin D (CD) plays a role in neurodegenerative diseases, cancer, and embryo-fetus abnormalities. It is therefore of interest to know how this protein is synthesized in animal species used for modeling human diseases. Zebrafish (Danio rerio) is emerging as a valuable 'in vivo' vertebrate model for several human diseases. We have characterized the biogenetic pathways of zebrafish and human CD transgenically expressed in both human SH-SY5Y cells and zebrafish PAC2 cells. Differently from human CD, zebrafish CD was synthesized as a mono-glycosylated precursor (pro-CD) that was eventually processed into a single-chain mature polypeptide. In PAC2 cells, ammonium chloride and chloroquine impaired the N-glycosylation, and greatly stimulated the secretion, of pro-CD; still, a portion of un-glycosylated pro-CD reached the lysosomes and was processed to mature CD. The treatment with tunicamycin, which abrogates N-glycosylation, resulted in a similar effect. Zebrafish pro-CD was correctly processed when expressed in human cells, and its glycosylation, transport and maturation were not impaired by ammonium chloride. On the contrary, the transport and processing of human pro-CD expressed in zebrafish cells were profoundly altered: while the intermediate single-chain was not detectable, a small amount of double-chain mature CD still formed. This fact indicates that the enzyme machinery for single- to double-chain processing of mammal CD is present in zebrafish. Our data highlight the respective impact of the information imparted by the primary sequence and of the cellular transport and processing machineries in the biogenesis of lysosomal CD.
Thai traditional medicine employs a wide range of indigenous herbs in the forms of tincture or tea for the cure of skin and systemic inflammatory diseases. The protection by Thai plants extracts against UVB DNA damage and cytotoxicity was investigated in human keratinocytes. Petroleum ether, dichloromethane and ethanol extracts were prepared from 15 Thai herb species, and the total phenolic and flavonoid contents, the antioxidant and UV-absorbing properties were assessed by standard procedures. Cytoprotective effects were evaluated on the basis of cell survival, caspase-3 activity and pyrimidine dimers determination. High total phenolic and flavonoid contents were found in the ethanol and dichloromethane fractions. Dichloromethane extract of turmeric was shown to possess the highest antioxidant activity. The maximum UV absorptions were found in the ethanol extract of turmeric and in the dichloromethane extract of ginger. These extracts stimulated the synthesis of Thioredoxin 1, an antioxidant protein, and could protect human HaCaT keratinocytes from UV-induced DNA damage and cytotoxicity. The present data support the utilization of turmeric and ginger extracts in anti-UV cosmetic pharmaceuticals.
Labeling and exocytosis of secretory compartments in RBL mastocytes by polystyrene and mesoporous silica nanoparticles.
BackgroundFor a safe 'in vivo' biomedical utilization of nanoparticles, it is essential to assess not only biocompatibility, but also the potential to trigger unwanted side effects at both cellular and tissue levels. Mastocytes (cells having secretory granules containing cytokines, vasoactive amine, and proteases) play a pivotal role in the immune and inflammatory responses against exogenous toxins. Mastocytes are also recruited in the tumor stroma and are involved in tumor vascularization and growth.Aim and methodsIn this work, mastocyte-like rat basophilic leukemia (RBL) cells were used to investigate whether carboxyl-modified 30 nm polystyrene (PS) nanoparticles (NPs) and naked mesoporous silica (MPS) 10 nm NPs are able to label the secretory inflammatory granules, and possibly induce exocytosis of these granules. Uptake, cellular retention and localization of fluorescent NPs were analyzed by cytofluorometry and microscope imaging.ResultsOUR FINDINGS WERE THAT: (1) secretory granules of mastocytes are accessible by NPs via endocytosis; (2) PS and MPS silica NPs label two distinct subpopulations of inflammatory granules in RBL mastocytes; and (3) PS NPs induce calcium-dependent exocytosis of inflammatory granules.ConclusionThese findings highlight the value of NPs for live imaging of inflammatory processes, and also have important implications for the clinical use of PS-based NPs, due to their potential to trigger the unwanted activation of mastocytes.
Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups.
Background and methodsNanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10-30 nm versus 50 nm), type of material (mesoporous silica versus polystyrene), and surface charge functionalization (none, amine groups, or carboxyl groups) on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles.ResultsWe found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles.ConclusionThese data highlight the importance of considering both the physicochemical characteristics (ie, material, size and surface charge on chemical groups) of nanoparticles and the biochemical composition of the cell membrane when choosing the most suitable nanotheranostics for targeting cancer cells.
Chloroquine/ hydroxychloroquine prevention of coronavirus disease (COVID-19) in the healthcare setting; protocol for a randomised, placebo-controlled prophylaxis study (COPCOV)
There is no proven preventative therapy or vaccine against COVID-19. Theinfection has spread rapidly and there has already been a substantial adverse impact on the global economy. Healthcare workers have been affected disproportionately in the continuing pandemic. Significant infection rates in this critical group have resulted in a breakdown of health services in some countries. Chloroquine, and the closely related hydroxychloroquine, are safe and well tolerated medications which can be given for years without adverse effects. Chloroquine and hydroxychloroquine have significant antiviral activity against SARS-CoV-2, and despite the lack of benefit of hydroxychloroquine treatment in patients hospitalised with severe COVID-19, these drugs could still work in prevention. The emerging infection paradigm of an early viral peak, and late inflammation where there is benefit from corticosteroids. If these direct actiing antivirals are to work, they have the best chance given either early in infection and before infection occurs. We describe the study protocol for a multi-centre, multi-country randomised, double blind, placebo controlled trial to answer the question- can chloroquine/ hydroxychloroquine prevent COVID-19. 40,000 participants working in healthcare facilities or involved in the management of COVID-19 will be randomised 1:1 to receive chloroquine/ hydroxychloroquine or matched placebo as daily prophylaxis for three months. The primary objective is the prevention of symptomatic, virological or serologically proven coronavirus disease (COVID-19). The study could detect a 23% reduction from an incidence of 3% in the placebo group for either drug with 80% power. Secondary objectives are to determine if chloroquine/hydroxychloroquine prophylaxis attenuates severity, prevents asymptomaticCOVID-19 and symptomatic acute respiratory infections of another aetiology (non-SARS-CoV-2).
Excess Mortality Attributable to Hospital-Acquired Antimicrobial-Resistant Infections: A 2-Year Prospective Surveillance Study in Northeast Thailand.
BackgroundQuantifying the excess mortality attributable to antimicrobial-resistant (AMR) bacterial infections is important for assessing the potential benefit of preventive interventions and for prioritization of resources. However, there are few data from low- and middle-income countries.MethodsWe conducted a 2-year prospective surveillance study to estimate the excess mortality attributable to AMR infections for all types of hospital-acquired infection (HAI), and included bacterial species that were both locally relevant and included in the World Health Organization priority list. Twenty-eight-day mortality was measured. Excess mortality and population attributable fraction (PAF) of mortality caused by AMR infections compared to antimicrobial-susceptible (AMS) infections, adjusted for predefined confounders, were calculated.ResultsWe enrolled 2043 patients with HAIs. The crude 28-day mortality of patients with AMR and AMS infections was 35.5% (491/1385) and 23.1% (152/658), respectively. After adjusting for prespecified confounders, the estimated excess mortality attributable to AMR infections was 7.7 (95% confidence interval [CI], 2.2-13.2) percentage points. This suggests that 106 (95% CI, 30-182) deaths among 1385 patients with AMR infections might have been prevented if all of the AMR infections in this study were AMS infections. The overall PAF was 16.3% (95% CI, 1.2%-29.1%). Among the bacteria under evaluation, carbapenem-resistant Acinetobacter baumannii was responsible for the largest number of excess deaths. Among all types of infection, urinary tract infections were associated with the highest number of excess deaths, followed by lower respiratory tract infections and bloodstream infections.ConclusionsEstimating and monitoring excess mortality attributable to AMR infections should be included in national action plans to prioritize targets of preventive interventions.Clinical trials registrationNCT03411538.
Emerging artemisinin resistance in Plasmodium falciparum malaria has the potential to become a global public health crisis. In Southeast Asia, this phenomenon clinically manifests in the form of delayed parasite clearance following artemisinin treatment. Reduced artemisinin susceptibility is limited to the early ring stage window, which is sufficient to allow parasites to survive the short half-life of artemisinin exposure. A screen of known clinically-implemented antimalarial drugs was performed to identify a drug capable of enhancing the killing activity of artemisinins during this critical resistance window. As a result, lumefantrine was found to increase the killing activity of artemisinin against an artemisinin-resistant clinical isolate harboring the C580Y kelch13 mutation. Isobologram analysis revealed synergism during the early ring stage resistance window, when lumefantrine was combined with artemether, an artemisinin derivative clinically partnered with lumefantrine. These findings suggest that lumefantrine should be clinically explored as a partner drug in artemisinin-based combination therapies to control emerging artemisinin resistance.
Abstract Objective Antimalarial chemoprophylaxis for high risk groups in endemic areas of Southeast Asia has the potential to reduce malaria transmission and accelerate elimination. However, the optimal choice of medication and dosing for many potential candidates is not clear. For a planned randomised controlled trial of prophylaxis for forest goers in Cambodia, artemether-lumefantrine (AL) was selected because of its ongoing efficacy and excellent tolerability and safety. As AL had not been used before for this purpose, a previously published pooled pharmacometric meta-model was used to determine the optimal dosing schedule. Results A full 3 day AL treatment course given twice a month, and twice daily treatment given once a week, resulted in trough concentrations consistently above the therapeutic threshold of 200 ng/mL. However, the most favourable exposure profile, and arguably most practical dosing scenario, was an initial 3 day full AL treatment course followed by twice daily dosing given once a week for the duration of chemoprevention. The latter was adopted as the dosing schedule for the trial.
Simultaneous and enantiospecific quantification of primaquine and carboxyprimaquine in human plasma using liquid chromatography-tandem mass spectrometry
Abstract Background The enantiomers of the 8-aminoquinoline anti-malarial primaquine have different pharmacological properties. Development of an analytical method for simultaneous quantification of the enantiomers of primaquine and its metabolite, carboxyprimaquine, will support clinical pharmacometric assessments. Methods A simple and sensitive method consisting of liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) was developed for simultaneous and enantiospecific determination of primaquine and its metabolite, carboxyprimaquine, in human plasma. Stable isotopes were used as internal standards to compensate for potential interference and matrix effects. Plasma samples (100 µL) were precipitated with 1% formic acid in acetonitrile followed by phospholipid removal solid phase extraction. Primaquine and carboxyprimaquine enantiomers were separated on a Chiralcel OD-3R (150 mm × 4.6 mm; I.D. 3 μm) column using a LC gradient mode. For separation of racemic primaquine and carboxyprimaquine, the LC method was modified and validated using a reverse phase column (Hypersil Gold 100 mm × 4.6 mm; I.D. 3 µm) and a mobile phase composed of 10 mM ammonium acetate buffer, pH 3.5 and acetonitrile in the isocratic mode. Method validation was performed according to regulatory guidelines. Results The calibration range was set to 0.571–260 ng/mL and 2.44–2,500 ng/mL for primaquine and carboxyprimaquine enantiomers, respectively, resulting in a correlation coefficient (r2) ≥ 0.0998 for all calibration curves. The intra- and inter-day assay precisions were < 10% and the accuracy was between 94.7 to 103% for all enantiomers of primaquine and carboxyprimaquine. The enantiospecific method was also modified and validated to quantify racemic primaquine and carboxyprimaquine, reducing the total run time from 30 to 8 min. The inter-, intra-day assay precision of the racemic quantification method was < 15%. The absolute recoveries of primaquine and carboxyprimaquine were between 70 and 80%. Stability was demonstrated for up to 2 years in − 80 °C. Both the enantiomeric and racemic LC–MS/MS methods were successfully implemented in pharmacokinetic studies in healthy volunteers. Conclusions Simple, sensitive and accurate LC–MS/MS methods for the quantification of enantiomeric and racemic primaquine and carboxyprimaquine in human plasma were validated successfully and implemented in clinical routine drug analysis.
Mechanistic Modeling of Primaquine Pharmacokinetics, Gametocytocidal Activity, and Mosquito Infectivity.
Clinical studies have shown that adding a single 0.25 mg base/kg dose of primaquine to standard antimalarial regimens rapidly sterilizes Plasmodium falciparum gametocytes. However, the mechanism of action and overall impact on malaria transmission is still unknown. Using data from 81 adult Malians with P. falciparum gametocytemia who received the standard dihydroartemisinin-piperaquine treatment course and were randomized to receive either a single dose of primaquine between 0.0625 and 0.5 mg base/kg or placebo, we characterized the pharmacokinetic-pharmacodynamic relationships for transmission blocking activity. Both gametocyte clearance and mosquito infectivity were assessed. A mechanistically linked pharmacokinetic-pharmacodynamic model adequately described primaquine and carboxy-primaquine pharmacokinetics, gametocyte dynamics, and mosquito infectivity at different clinical doses of primaquine. Primaquine showed a dose-dependent gametocytocidal effect that precedes clearance. A single low dose of primaquine (0.25 mg/kg) rapidly prevented P. falciparum transmissibility.
Host Biomarkers Reflect Prognosis in Patients Presenting With Moderate Coronavirus Disease 2019: A Prospective Cohort Study.
Efficient resource allocation is essential for effective pandemic response. We measured host biomarkers in 420 patients presenting with moderate coronavirus disease 2019 and found that different biomarkers predict distinct clinical outcomes. Interleukin (IL)-1ra, IL-6, IL-10, and IL-8 exhibit dose-response relationships with subsequent disease progression and could potentially be useful for multiple use-cases.
Reference spectrophotometric values for glucose-6-phosphate dehydrogenase activity in two-to six-month-old infants on the Thailand-Myanmar border
Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency represents a barrier to the full deployment of anti-malarial drugs for vivax malaria elimination and of first-line antibiotics. Lack of established reference ranges for G6PD activity in breast-fed infants puts them at risk of drug-induced haemolysis and restricts access to safe treatment of their mothers. Methods: The present work was undertaken to establish age-specific G6PD normal values using the gold standard spectrophotometric assay to support the future clinical use of tafenoquine in lactating women and safer antibiotic treatment in infants. Results: Spectrophotometric results from 78 healthy infants between the ages of 2 and 6 months showed a trend of decreased enzymatic activity with increasing age and provided a reference normal value of 100% activity for infants 2-6 months old of 10.18IU/gHb. Conclusions: Normal reference G6PD activity in 2–6-month-old infants was approximately 140% of that observed in G6PD normal adults from the same population. Age specific G6PD activity thresholds should be used in paediatric populations to avoid drug-induced haemolysis.