Janardan Subedi

Publications (28) View all

• Article: The Continued Salience of Methodological Issues for Measuring Psychiatric Disorders in International Surveys

  Mark Tausig, Janardan Subedi, Christopher Broughton, Jelena Pokimica, Yinmei Huang, Susan L. Santangelo
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  ABSTRACT: We investigated the extent to which methodological concerns explicitly addressed by the designers of the World Mental Health Surveys persist in the results that were obtained using the WMH-CIDI instrument. We compared rates of endorsement of mental illness symptoms in the United States (very high) and Nepal (very low) as they were affected by respondent understanding of the survey, social desirability bias, interview social context and translation-related sources of misunderstanding. The results showed that, although levels of misunderstanding and social desirability were higher in Nepal than in the U.S., these potential methodological concerns had less effect on symptom endorsement in Nepal than in the U.S. In Nepal non-methodological factors related to the socio-cultural context probably had a more substantial impact on observed symptom rates than did the methodological factors. The larger issue is the effect that methodological factors have on the validity of reported rates of disorder. KeywordsMeasurement–Psychiatric disorder–Reliability
  International Journal of Mental Health and Addiction 04/2012; 9(3):229-239.
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  Available from: Janardan Subedi

  Article: Host genetics and population structure effects on parasitic disease.

  Sarah Williams-Blangero, Charles D Criscione, John L VandeBerg, Rodrigo Correa-Oliveira, Kimberly D Williams, Janardan Subedi, Jack W Kent, Jeff Williams, Satish Kumar, John Blangero
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  ABSTRACT: Host genetic factors exert significant influences on differential susceptibility to many infectious diseases. In addition, population structure of both host and parasite may influence disease distribution patterns. In this study, we assess the effects of population structure on infectious disease in two populations in which host genetic factors influencing susceptibility to parasitic disease have been extensively studied. The first population is the Jirel population of eastern Nepal that has been the subject of research on the determinants of differential susceptibility to soil-transmitted helminth infections. The second group is a Brazilian population residing in an area endemic for Trypanosoma cruzi infection that has been assessed for genetic influences on differential disease progression in Chagas disease. For measures of Ascaris worm burden, within-population host genetic effects are generally more important than host population structure factors in determining patterns of infectious disease. No significant influences of population structure on measures associated with progression of cardiac disease in individuals who were seropositive for T. cruzi infection were found.
  Philosophical Transactions of The Royal Society B Biological Sciences 03/2012; 367(1590):887-94. · 6.40 Impact Factor
• Article: Evaluation of qualitative methods for phenotyping brachymesophalangia-V from radiographs of children.

  Kimberly D Williams, Ramzi W Nahhas, Carol R Cottom, Sharon Lawrence, Janardan Subedi, Bharat Jha, Stefan A Czerwinski, John Blangero, Sarah Williams-Blangero, Bradford Towne
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  ABSTRACT: Brachymesophalangia-V (BMP-V), the general term for a short and broad middle phalanx of the 5th digit, presents both alone and in a large number of complex brachydactylies and developmental disorders. Past anthropological and epidemiological studies of growth and development have examined the prevalence of BMP-V because small developmental disorders may signal more complex disruptions of skeletal growth and development. Historically, however, consensus on qualitative phenotype methodology has not been established. In large-scale, non-clinical studies such as the Fels Longitudinal Study and the Jiri Growth Study, quantitative assessment of the hand is not always the most efficient manner of screening for skeletal dysmorphologies. The current study evaluates qualitative phenotyping techniques for BMP-V used in past anthropological studies of growth and development to establish a useful and reliable screening method for large study samples. A total of 1,360 radiographs from Jiri Growth Study participants aged 3-18 years were evaluated. BMP-V was assessed using three methods: (1) subjective evaluation of length and width of the bone; (2) comparison with skeletal age-matched radiographs; and (3) subjective evaluation of the length of the middle 4th and 5th phalanges. We found that the method that uses skeletal age-matched reference radiographs is the better tool for assessing BMP-V because it considers the shape, rather than solely the length and width of the bone, which can be difficult to judge accurately without measurement. This study highlights the complexity of phenotypic assessment of BMP-V and by extension other brachydactylies.
  American Journal of Human Biology 12/2011; 24(1):68-73. · 2.27 Impact Factor
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  Article: Landscape genetics reveals focal transmission of a human macroparasite.

  Charles D Criscione, Joel D Anderson, Dan Sudimack, Janardan Subedi, Ram P Upadhayay, Bharat Jha, Kimberly D Williams, Sarah Williams-Blangero, Timothy J C Anderson
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  ABSTRACT: Macroparasite infections (e.g., helminths) remain a major human health concern. However, assessing transmission dynamics is problematic because the direct observation of macroparasite dispersal among hosts is not possible. We used a novel landscape genetics approach to examine transmission of the human roundworm Ascaris lumbricoides in a small human population in Jiri, Nepal. Unexpectedly, we found significant genetic structuring of parasites, indicating the presence of multiple transmission foci within a small sampling area ( approximately 14 km(2)). We analyzed several epidemiological variables, and found that transmission is spatially autocorrelated around households and that transmission foci are stable over time despite extensive human movement. These results would not have been obtainable via a traditional epidemiological study based on worm counts alone. Our data refute the assumption that a single host population corresponds to a single parasite transmission unit, an assumption implicit in many classic models of macroparasite transmission. Newer models have shown that the metapopulation-like pattern observed in our data can adversely affect targeted control strategies aimed at community-wide impacts. Furthermore, the observed metapopulation structure and local mating patterns generate an excess of homozygotes that can accelerate the spread of recessive traits such as drug resistance. Our study illustrates how molecular analyses complement traditional epidemiological information in providing a better understanding of parasite transmission. Similar landscape genetic approaches in other macroparasite systems will be warranted if an accurate depiction of the transmission process is to be used to inform effective control strategies.
  PLoS Neglected Tropical Diseases 01/2010; 4(4):e665. · 4.69 Impact Factor
• Conference Proceeding: Suggestive Linkage for an Electrophysiological Trait Indexing a Schizophrenia Endophenotype in a Nepalese Population Genetic Isolate

  Susan L. Santangelo, Tatiana Sitnikova, Payas Shrestha, Mei Hua Hall, Dongmei Yu, Saroj Prasad Ojha, Janardan Subedi, Ram Hari Chapagain, Sher Bahadur Kamar, John L. VandeBerg, John Blangero, Sarah Williams-Blangero
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  ABSTRACT: Electrophysiological traits, indexing schizophrenia endophenotypes, were measured in over 600 members of a genetic isolate in Jiri, Nepal, who are members of a single pedigree. Measured traits include P50 and P300 amplitude and latency, and oscillatory brain activity in the gammaband range (35–45 Hz). The power of induced gammaband activity, as measured in the classic auditory oddball paradigm, was calculated at the PZ, P3 and P4 scalp locations in 614 individuals and evaluated in a quantitative trait locus (QTL) genome-wide linkage analysis. Heritabilities for gamma response at all three scalp locations were significant. QTL linkage analysis for gamma response yielded peak LOD scores of 1.63 on chromosome 6 (182 cM) for PZ; 1.42 on chromosome 2 (98 cM) for P3, and 1.84 on chromosome 2 (98 cM) for P4, which qualifies as suggestive linkage in this pedigree and marker set. There was also a LOD of 1.31 on chromosome 2 (98 cM) for PZ. Therefore, suggestive linkage was obtained at chromosome 2p13 at the P4 electrode, with similar signals at the same chromosomal location at the PZ and P3 electrodes. Linkage to this same region was previously found for schizophrenia in another population isolate in Palau, Micronesia. Genes in this region include sepiapterin reductase (SPR), an enzyme that catalyzes the final step in the synthesis of tetrahydrobiopterin (BH4), an essential cofactor for synthesis of many neurotransmitters, including serotonin. 170
  18th Annual Meeting of the International-Genetic-Epidemiology-Society Location: Honolulu, HI Date: OCT 10-20, 2009; 10/2009