Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-9 (of 9 Records) |
Query Trace: Muralidharan S[original query] |
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The ER chaperone PfGRP170 is essential for asexual development and is linked to stress response in malaria parasites (preprint)
Kudyba HM , Cobb DW , Fierro MA , Florentin A , Ljolje D , Singh B , Lucchi NW , Muralidharan V . bioRxiv 2019 406181 The vast majority of malaria mortality is attributed to one parasite species: Plasmodium falciparum. Asexual replication of the parasite within the red blood cell is responsible for the pathology of the disease. In Plasmodium, the endoplasmic reticulum (ER) is a central hub for protein folding and trafficking as well as stress response pathways. In this study, we tested the role of an uncharacterized ER protein, PfGRP170, in regulating these key functions by generating conditional mutants. Our data show that PfGRP170 localizes to the ER and is essential for asexual growth, specifically required for proper development of schizonts. PfGRP170 is essential for surviving heat shock, suggesting a critical role in cellular stress response. The data demonstrate that PfGRP170 interacts with the Plasmodium orthologue of the ER chaperone, BiP. Finally, we found that loss of PfGRP170 function leads to the activation of the Plasmodium eIF2α kinase, PK4, suggesting a specific role for this protein in this parasite stress response pathway. |
Field evaluation of malachite green loop-mediated isothermal amplification as a malaria parasite detection tool in a health post in Roraima state, Brazil (preprint)
Kudyba HM , Louzada J , Ljolje D , Kudyba KA , Muralidharan V , Oliveira-Ferreira J , Lucchi NW . bioRxiv 2018 408609 Malaria is a debilitating parasitic disease that causes significant morbidity and mortality. Microscopic detection of parasites is currently the “gold standard” diagnostic. This technique is limited in its ability to detect low-density infections, is time consuming, and requires a highly trained microscopist. Malaria epidemiological surveillance studies especially aimed at the detection of low-density infection and asymptomatic cases will require more sensitive and user-friendly tools. We have shown previously that the molecular-based, colorimetric malachite green loop-mediated isothermal amplification (MG-LAMP) assay is a valuable tool for diagnosing malaria infection in a laboratory setting. In this study, we field evaluated this assay in a malaria diagnostic post in Roraima, Brazil. We prospectively collected 91 patient samples and performed microscopy, MG-LAMP, and real-time PCR (PET-PCR) to detect Plasmodium infection. Two independent readers were used to score the MG-LAMP tests to assess whether the sample was positive (blue/green) or negative (clear). There was 100% agreement between the two readers (Kappa=1). All tests detected 33 positive samples, but both the MG-LAMP and PET-PCR detected 6 and 7 more positive samples, respectively. The PET-PCR assay detected 6 mixed infections (defined as infection with both P. falciparum and P. vivax) while microscopy detected one and MG-LAMP detected two of these mixed infections. Microscopy did not detect any Plasmodium infection in 26 of the enrolled asymptomatic cases while MG-LAMP detected five and PET-PCR assay three positive cases. Overall, MG-LAMP provided a simpler and user-friendly molecular method for malaria diagnosis that is more sensitive than microscopy. Additionally, MG- LAMP has the capacity to test 38 samples per run (one hour), allowing for the screening of large number of samples which is appealing when large-scale studies are necessary e.g. in community surveillance studies. The current MG-LAMP assay was limited in its ability to detect mixed infection when compared to the PET-PCR, but otherwise proved to be a powerful tool for malaria parasite detection in the field and opens new perspectives in the implementation of surveillance studies in malaria elimination campaigns. |
Characterization of Reference Materials for Spinal Muscular Atrophy Genetic Testing: A GeT-RM Collaborative Project.
Prior TW , Bayrak-Toydemir P , Lynnes TC , Mao R , Metcalf JD , Muralidharan K , Iwata-Otsubo A , Pham HT , Pratt VM , Qureshi S , Requesens D , Shen J , Vetrini F , Kalman L . J Mol Diagn 2020 23 (1) 103-110 Spinal muscular atrophy (SMA) is an autosomal recessive disorder predominately caused by bi-allelic loss of the SMN1 gene. Increased copies of SMN2, a low functioning nearly identical paralog, is associated with a less severe phenotype. SMA was recently recommended for inclusion in newborn screening. Clinical laboratories must accurately measure SMN1 and SMN2 copy number to identify SMA patients, carriers, and to identify individuals likely to benefit from therapeutic interventions. Having publicly available and appropriately characterized reference materials with various combinations of SMN1 and SMN2 copy number variants is critical to assure accurate SMA clinical testing. To address this need, the Centers for Disease Control and Prevention based Genetic Testing Reference Material Coordination Program (GeT-RM), in collaboration with members of the genetic testing community and the Coriell Institute for Medical Research, have characterized 15 SMA reference materials derived from publicly available cell lines. DNA samples were distributed to four volunteer testing laboratories for genotyping using 3 different methods. The characterized samples had 0-4 copies of SMN1 and 0-5 copies SMN2. The samples also contained clinically important allele combinations (eg. 0 copies SMN1, 3 copies SMN2), and several had markers indicative of a SMA carrier. These and other reference materials characterized by the GeT-RM will support the quality of clinical laboratory testing and are available from the Coriell Institute. |
Engagement and weight loss: Results from the Mobile Health and Diabetes Trial
Muralidharan S , Ranjani H , Mohan Anjana R , Jena S , Tandon N , Gupta Y , Ambekar S , Koppikar V , Jagannathan N , Allender S , Mohan V . Diabetes Technol Ther 2019 21 (9) 507-513 Background: Prevalence of type 2 diabetes (T2D) is increasing worldwide. Identifying and targeting individuals at high risk, is essential for preventing T2D. Several studies point to mobile health initiatives delivered through personal smart devices being a promising approach to diabetes prevention, through weight loss. The aim of the mobile health and diabetes (mDiab) trial was twofold: to achieve 5% weight loss and to look at the association of weight loss with degree of engagement with the mDiab app. Methods: The mDiab randomized control trial was carried out among smartphone users who are at high risk for T2D mellitus in three cities-Chennai, Bengaluru, and New Delhi in India. The intervention was delivered through a mobile phone application along with weekly coach calls for 12 weeks. While individuals in the intervention group individuals received the app, which enabled tracking their weight, physical activity, and diet along with 12 weekly video lessons on T2D prevention and coach calls, the control group received usual care. Results: The intervention group experienced a significant 1 kg weight loss while the control group lost 0.3 kg (P < 0.05). More individuals in the intervention group (n = 139, 15%) met the 5% weight loss target than in the control group (n = 131, 9%). In the intervention group those who viewed the videos experienced greater weight loss (2.4 kg) than those who only attended coach calls (0.9 kg) (P < 0.01). Conclusions: An mHealth intervention helped to achieve moderate weight loss. Future studies should explore the sustainability of this weight loss. |
The ER chaperone PfGRP170 is essential for asexual development and is linked to stress response in malaria parasites
Kudyba HM , Cobb DW , Fierro MA , Florentin A , Ljolje D , Singh B , Lucchi NW , Muralidharan V . Cell Microbiol 2019 21 (9) e13042 The vast majority of malaria mortality is attributed to one parasite species: Plasmodium falciparum. Asexual replication of the parasite within the red blood cell is responsible for the pathology of the disease. In Plasmodium, the endoplasmic reticulum (ER) is a central hub for protein folding and trafficking as well as stress response pathways. In this study, we tested the role of an uncharacterized ER protein, PfGRP170, in regulating these key functions by generating conditional mutants. Our data show that PfGRP170 localizes to the ER and is essential for asexual growth, specifically required for proper development of schizonts. PfGRP170 is essential for surviving heat shock, suggesting a critical role in cellular stress response. The data demonstrate that PfGRP170 interacts with the Plasmodium orthologue of the ER chaperone, BiP. Finally, we found that loss of PfGRP170 function leads to the activation of the Plasmodium eIF2alpha kinase, PK4, suggesting a specific role for this protein in this parasite stress response pathway. |
Field evaluation of malaria malachite green loop-mediated isothermal amplification in health posts in Roraima state, Brazil
Kudyba HM , Louzada J , Ljolje D , Kudyba KA , Muralidharan V , Oliveira-Ferreira J , Lucchi NW . Malar J 2019 18 (1) 98 BACKGROUND: Microscopic detection of malaria parasites is the standard method for clinical diagnosis of malaria in Brazil. However, malaria epidemiological surveillance studies specifically aimed at the detection of low-density infection and asymptomatic cases will require more sensitive and field-usable tools. The diagnostic accuracy of the colorimetric malachite green, loop-mediated, isothermal amplification (MG-LAMP) assay was evaluated in remote health posts in Roraima state, Brazil. METHODS: Study participants were prospectively enrolled from health posts (healthcare-seeking patients) and from nearby villages (healthy participants) in three different study sites. The MG-LAMP assay and microscopy were performed in the health posts. Two independent readers scored the MG-LAMP tests as positive (blue/green) or negative (clear). Sensitivity and specificity of local microscopy and MG-LAMP were calculated using results of PET-PCR as a reference. RESULTS: A total of 91 participants were enrolled. There was 100% agreement between the two MG-LAMP readers (Kappa = 1). The overall sensitivity and specificity of MG-LAMP were 90.0% (95% confidence interval (CI) 76.34-97.21%) and 94% (95% CI 83.76-98.77%), respectively. The sensitivity and specificity of local microscopy were 83% (95% CI 67.22-92.66%) and 100% (95% CI 93.02-100.00%), respectively. PET-PCR detected six mixed infections (infection with both Plasmodium falciparum and Plasmodium vivax); two of these were also detected by MG-LAMP and one by microscopy. Microscopy did not detect any Plasmodium infection in the 26 healthy participants; MG-LAMP detected Plasmodium in five of these and PET-PCR assay detected infection in three. Overall, performing the MG-LAMP in this setting did not present any particular challenges. CONCLUSION: MG-LAMP is a sensitive and specific assay that may be useful for the detection of malaria parasites in remote healthcare settings. These findings suggest that it is possible to implement simple molecular tests in facilities with limited resources. |
HIV/AIDS-related mortality in Africa and Asia: evidence from INDEPTH Health and Demographic Surveillance System sites
Streatfield PK , Khan WA , Bhuiya A , Hanifi SM , Alam N , Millogo O , Sie A , Zabre P , Rossier C , Soura AB , Bonfoh B , Kone S , Ngoran EK , Utzinger J , Abera SF , Melaku YA , Weldearegawi B , Gomez P , Jasseh M , Ansah P , Azongo D , Kondayire F , Oduro A , Amu A , Gyapong M , Kwarteng O , Kant S , Pandav CS , Rai SK , Juvekar S , Muralidharan V , Wahab A , Wilopo S , Bauni E , Mochamah G , Ndila C , Williams TN , Khagayi S , Laserson KF , Nyaguara A , Van Eijk AM , Ezeh A , Kyobutungi C , Wamukoya M , Chihana M , Crampin A , Price A , Delaunay V , Diallo A , Douillot L , Sokhna C , Gómez-Olivé FX , Mee P , Tollman SM , Herbst K , Mossong J , Chuc NT , Arthur SS , Sankoh OA , Byass P . Glob Health Action 2014 7 25370 BACKGROUND: As the HIV/AIDS pandemic has evolved over recent decades, Africa has been the most affected region, even though a large proportion of HIV/AIDS deaths have not been documented at the individual level. Systematic application of verbal autopsy (VA) methods in defined populations provides an opportunity to assess the mortality burden of the pandemic from individual data. OBJECTIVE: To present standardised comparisons of HIV/AIDS-related mortality at sites across Africa and Asia, including closely related causes of death such as pulmonary tuberculosis (PTB) and pneumonia. DESIGN: Deaths related to HIV/AIDS were extracted from individual demographic and VA data from 22 INDEPTH sites across Africa and Asia. VA data were standardised to WHO 2012 standard causes of death assigned using the InterVA-4 model. Between-site comparisons of mortality rates were standardised using the INDEPTH 2013 standard population. RESULTS: The dataset covered a total of 10,773 deaths attributed to HIV/AIDS, observed over 12,204,043 person-years. HIV/AIDS-related mortality fractions and mortality rates varied widely across Africa and Asia, with highest burdens in eastern and southern Africa, and lowest burdens in Asia. There was evidence of rapidly declining rates at the sites with the heaviest burdens. HIV/AIDS mortality was also strongly related to PTB mortality. On a country basis, there were strong similarities between HIV/AIDS mortality rates at INDEPTH sites and those derived from modelled estimates. CONCLUSIONS: Measuring HIV/AIDS-related mortality continues to be a challenging issue, all the more so as anti-retroviral treatment programmes alleviate mortality risks. The congruence between these results and other estimates adds plausibility to both approaches. These data, covering some of the highest mortality observed during the pandemic, will be an important baseline for understanding the future decline of HIV/AIDS. |
Characterization of 107 genomic DNA reference materials for CYP2D6, CYP2C19, CYP2C9, VKORC1, and UGT1A1. A GeT-RM and Association for Molecular Pathology collaborative project
Pratt VM , Zehnbauer B , Wilson JA , Baak R , Babic N , Bettinotti M , Buller A , Butz K , Campbell M , Civalier C , El-Badry A , Farkas DH , Lyon E , Mandal S , McKinney J , Muralidharan K , Noll L , Sander T , Shabbeer J , Smith C , Telatar M , Toji L , Vairavan A , Vance C , Weck KE , Wu AH , Yeo KT , Zeller M , Kalman L . J Mol Diagn 2010 12 (6) 835-46 Pharmacogenetic testing is becoming more common; however, very few quality control and other reference materials that cover alleles commonly included in such assays are currently available. To address these needs, the Centers for Disease Control and Prevention's Genetic Testing Reference Material Coordination Program, in collaboration with members of the pharmacogenetic testing community and the Coriell Cell Repositories, have characterized a panel of 107 genomic DNA reference materials for five loci (CYP2D6, CYP2C19, CYP2C9, VKORC1, and UGT1A1) that are commonly included in pharmacogenetic testing panels and proficiency testing surveys. Genomic DNA from publicly available cell lines was sent to volunteer laboratories for genotyping. Each sample was tested in three to six laboratories using a variety of commercially available or laboratory-developed platforms. The results were consistent among laboratories, with differences in allele assignments largely related to the manufacturer's assay design and variable nomenclature, especially for CYP2D6. The alleles included in the assay platforms varied, but most were identified in the set of 107 DNA samples. Nine additional pharmacogenetic loci (CYP4F2, EPHX1, ABCB1, HLAB, KIF6, CYP3A4, CYP3A5, TPMT, and DPD) were also tested. These samples are publicly available from Coriell and will be useful for quality assurance, proficiency testing, test development, and research. |
Development of genomic DNA reference materials for genetic testing of disorders common in people of Ashkenazi Jewish descent
Kalman L , Wilson JA , Buller A , Dixon J , Edelmann L , Geller L , Highsmith WE , Holtegaard L , Kornreich R , Rohlfs EM , Payeur TL , Sellers T , Toji L , Muralidharan K . J Mol Diagn 2009 11 (6) 530-6 Many recessive genetic disorders are found at a higher incidence in people of Ashkenazi Jewish (AJ) descent than in the general population. The American College of Medical Genetics and the American College of Obstetricians and Gynecologists have recommended that individuals of AJ descent undergo carrier screening for Tay Sachs disease, Canavan disease, familial dysautonomia, mucolipidosis IV, Niemann-Pick disease type A, Fanconi anemia type C, Bloom syndrome, and Gaucher disease. Although these recommendations have led to increased test volumes and number of laboratories offering AJ screening, well-characterized genomic reference materials are not publicly available. The Centers for Disease Control and Prevention-based Genetic Testing Reference Materials Coordination Program, in collaboration with members of the genetic testing community and Coriell Cell Repositories, have developed a panel of characterized genomic reference materials for AJ genetic testing. DNA from 31 cell lines, representing many of the common alleles for Tay Sachs disease, Canavan disease, familial dysautonomia, mucolipidosis IV, Niemann-Pick disease type A, Fanconi anemia type C, Bloom syndrome, Gaucher disease, and glycogen storage disease, was prepared by the Repository and tested in six clinical laboratories using three different PCR-based assay platforms. A total of 33 disease alleles was assayed and 25 different alleles were identified. These characterized materials are publicly available from Coriell and may be used for quality control, proficiency testing, test development, and research. |
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