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result(s) for
"Thyagarajan, Bharat"
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Review of Clinical Next-Generation Sequencing
2017
- Next-generation sequencing (NGS) is a technology being used by many laboratories to test for inherited disorders and tumor mutations. This technology is new for many practicing pathologists, who may not be familiar with the uses, methodology, and limitations of NGS.
- To familiarize pathologists with several aspects of NGS, including current and expanding uses; methodology including wet bench aspects, bioinformatics, and interpretation; validation and proficiency; limitations; and issues related to the integration of NGS data into patient care.
- The review is based on peer-reviewed literature and personal experience using NGS in a clinical setting at a major academic center.
- The clinical applications of NGS will increase as the technology, bioinformatics, and resources evolve to address the limitations and improve quality of results. The challenge for clinical laboratories is to ensure testing is clinically relevant, cost-effective, and can be integrated into clinical care.
Journal Article
Cancer Treatment-Induced Accelerated Aging in Cancer Survivors: Biology and Assessment
2021
Rapid improvements in cancer survival led to the realization that many modalities used to treat or control cancer may cause accelerated aging in cancer survivors. Clinically, “accelerated aging” phenotypes in cancer survivors include secondary cancers, frailty, chronic organ dysfunction, and cognitive impairment, all of which can impact long-term health and quality of life in cancer survivors. The treatment-induced accelerated aging in cancer survivors could be explained by telomere attrition, cellular senescence, stem cell exhaustion, DNA damage, and epigenetic alterations. Several aging clocks and biomarkers of aging have been proposed to be potentially useful in estimating biological age, which can provide specific information about how old an individual is biologically independent of chronological age. Measuring biological age in cancer survivors may be important for two reasons. First, it can better predict the risk of cancer treatment-related comorbidities than chronological age. Second, biological age may provide additional value in evaluating the effects of treatments and personalizing cancer therapies to maximize efficacy of treatment. A deeper understanding of treatment-induced accelerated aging in individuals with cancer may lead to novel strategies that reduce the accelerated aging and improve the quality of life in cancer survivors.
Journal Article
Ultrasensitive detection of salivary SARS-CoV-2 IgG antibodies in individuals with natural and COVID-19 vaccine-induced immunity
by
Gorlin, Jed
,
Karger, Amy B.
,
Thyagarajan, Bharat
in
631/1647/2196/2197
,
631/45/612
,
Antibodies
2022
We assessed the feasibility of a highly sensitive immunoassay method based on single molecule array (Simoa) technology to detect IgG and IgA antibodies against SARS-CoV-2 spike protein receptor binding domain (RBD) in saliva from individuals with natural or vaccine-induced COVID-19 immunity. The performance of the method was compared to a laboratory-developed SARS-CoV-2 RBD total antibody enzyme-linked immunosorbent assay (ELISA). Paired serum and saliva specimens were collected from individuals (n = 40) prior to and 2 weeks after receiving an initial prime COVID-19 vaccine dose (Pfizer/BioNTech BNT162b2 or Moderna mRNA-1273). Saliva was collected using a commercially available collection device (OraSure Inc.) and SARS-CoV-2 RBD IgG antibodies were measured by an indirect ELISA using concentrated saliva samples and a Simoa immunoassay using unconcentrated saliva samples. The IgG results were compared with paired serum specimens that were analyzed for total RBD antibodies using the ELISA method. The analytical sensitivity of the saliva-based Simoa immunoassay was five orders of magnitude higher than the ELISA assay: 0.24 pg/mL compared to 15 ng/mL. The diagnostic sensitivity of the saliva ELISA method was 90% (95% CI 76.3–97.2%) compared to 91.7% (95% CI 77.5–98.2%) for the Simoa immunoassay without total IgG-normalization and 100% (95% CI 90.3–100%) for the Simoa immunoassay after total IgG-normalization when compared to the serum ELISA assay. When analyzed using the SARS-CoV-2 RBD IgG antibody ELISA, the average relative increase in antibody index (AI) between the saliva of the post- and pre-vaccinated individuals was 8.7 (AI
post/pre
). An average relative increase of 431 pg/mL was observed when the unconcentrated saliva specimens were analyzed using the Simoa immunoassay (SARS-CoV-2 RBD IgG
post/pre
). These findings support the suitability of concentrated saliva specimens for the measurement of SARS-CoV-2 RBD IgG antibodies via ELISA, and unconcentrated saliva specimens for the measurement of SARS-CoV-2 RBD IgG and IgA using an ultrasensitive Simoa immunoassay.
Journal Article
Gut microbiome composition in the Hispanic Community Health Study/Study of Latinos is shaped by geographic relocation, environmental factors, and obesity
2019
Background
Hispanics living in the USA may have unrecognized potential birthplace and lifestyle influences on the gut microbiome. We report a cross-sectional analysis of 1674 participants from four centers of the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), aged 18 to 74 years old at recruitment.
Results
Amplicon sequencing of 16S rRNA gene V4 and fungal ITS1 fragments from self-collected stool samples indicate that the host microbiome is determined by sociodemographic and migration-related variables. Those who relocate from Latin America to the USA at an early age have reductions in
Prevotella
to
Bacteroides
ratios that persist across the life course. Shannon index of alpha diversity in fungi and bacteria is low in those who relocate to the USA in early life. In contrast, those who relocate to the USA during adulthood, over 45 years old, have high bacterial and fungal diversity and high
Prevotella
to
Bacteroides
ratios, compared to USA-born and childhood arrivals. Low bacterial diversity is associated in turn with obesity. Contrasting with prior studies, our study of the Latino population shows increasing
Prevotella
to
Bacteroides
ratio with greater obesity. Taxa within Acidaminococcus, Megasphaera, Ruminococcaceae, Coriobacteriaceae, Clostridiales, Christensenellaceae, YS2 (Cyanobacteria), and Victivallaceae are significantly associated with both obesity and earlier exposure to the USA, while Oscillospira and Anaerotruncus show paradoxical associations with both obesity and late-life introduction to the USA.
Conclusions
Our analysis of the gut microbiome of Latinos demonstrates unique features that might be responsible for health disparities affecting Hispanics living in the USA.
Journal Article
CIMP Status of Interval Colon Cancers: Another Piece to the Puzzle
by
Thyagarajan, Bharat
,
Bond, John H
,
Arain, Mustafa A
in
Age Distribution
,
Aged
,
Aged, 80 and over
2010
Colon cancers diagnosed in the interval after a complete colonoscopy may occur due to limitations of colonoscopy or due to the development of new tumors, possibly reflecting molecular and environmental differences in tumorigenesis resulting in rapid tumor growth. In a previous study from our group, interval cancers (colon cancers diagnosed within 5 years of a complete colonoscopy) were almost four times more likely to demonstrate microsatellite instability (MSI) than non-interval cancers. In this study we extended our molecular analysis to compare the CpG island methylator phenotype (CIMP) status of interval and non-interval colorectal cancers and investigate the relationship between the CIMP and MSI pathways in the pathogenesis of interval cancers.
We searched our institution's cancer registry for interval cancers, defined as colon cancers that developed within 5 years of a complete colonoscopy. These were frequency matched in a 1:2 ratio by age and sex to patients with non-interval cancers (defined as colon cancers diagnosed on a patient's first recorded colonoscopy). Archived cancer specimens for all subjects were retrieved and tested for CIMP gene markers. The MSI status of subjects identified between 1989 and 2004 was known from our previous study. Tissue specimens of newly identified cases and controls (between 2005 and 2006) were tested for MSI.
There were 1,323 cases of colon cancer diagnosed over the 17-year study period, of which 63 were identified as having interval cancer and matched to 131 subjects with non-interval cancer. Study subjects were almost all Caucasian men. CIMP was present in 57% of interval cancers compared to 33% of non-interval cancers (P=0.004). As shown previously, interval cancers were more likely than non-interval cancers to occur in the proximal colon (63% vs. 39%; P=0.002), and have MSI 29% vs. 11%, P=0.004). In multivariable logistic regression model, proximal location (odds ratio (OR) 1.85; 95% confidence interval (CI) 1.01-3.8), MSI (OR 2.7; 95% CI 1.1-6.8) and CIMP (OR 2.41; 95% CI 1.2-4.9) were independently associated with interval cancers. CIMP was associated with interval cancers independent of MSI status. There was no difference in 5-year survival between the two groups.
Interval cancers are more likely to arise in the proximal colon and demonstrate CIMP, which suggests there may be differences in biology between these and non-interval CRC. Additional studies are needed to determine whether interval cancers arise as a result of missed lesions or accelerated neoplastic progression.
Journal Article
Cross sectional association between cytomegalovirus seropositivity, inflammation and cognitive impairment in elderly cancer survivors
by
Sithara, Vivek
,
Faul, Jessica
,
Thyagarajan Bharat
in
C-reactive protein
,
Cancer
,
Cognitive ability
2022
PurposeThe higher prevalence of cognitive impairment/ dementia among cancer survivors is likely multifactorial. Since both exposures to cytomegalovirus (CMV) and inflammation are common among elderly cancer survivors, we evaluated their contribution towards dementia.MethodsData from 1387 cancer survivors and 7004 participants without cancer in the 2016 wave of the Health and Retirement Study (HRS) was used in this study. Two inflammatory biomarkers, C-reactive protein (CRP) and neutrophil–lymphocyte ratio (NLR), were used to create an inflammation score. We used survey logistic regression adjusted for survey design parameters.ResultsCMV seropositivity was not associated with cognitive impairment among cancer survivors (p = 0.2). In addition, inflammation was associated with elevated odds of cognitive impairment (OR = 2.2, 95% CI [1.2, 4.2]). Cancer survivors who were both CMV seropositive and had increased inflammation had the highest odds of cognitive impairment compared to those who were CMV seronegative and had low inflammation (OR = 3.8, 95% CI [1.5, 9.4]). The stratified analysis among cancer survivors showed this association was seen only among cancer survivors in whom the cancer was diagnosed within three years of measurement of inflammation score and CMV serostatus (OR = 18.5; 95% CI [6.1, 56.1]).ConclusionThe CMV seropositivity and high inflammation was associated with higher cognitive impairment among cancer survivors. The stronger associations seen among cancer survivors diagnosed within the last three years suggest that strategies to reduce CMV activation and inflammation during or immediately after cancer treatment may be important in reducing the prevalence of cognitive impairment/ dementia among cancer survivors.
Journal Article
Microbial co-occurrence complicates associations of gut microbiome with US immigration, dietary intake and obesity
2021
Background
Obesity and related comorbidities are major health concerns among many US immigrant populations. Emerging evidence suggests a potential involvement of the gut microbiome. Here, we evaluated gut microbiome features and their associations with immigration, dietary intake, and obesity in 2640 individuals from a population-based study of US Hispanics/Latinos.
Results
The fecal shotgun metagenomics data indicate that greater US exposure is associated with reduced ɑ-diversity, reduced functions of fiber degradation, and alterations in individual taxa, potentially related to a westernized diet. However, a majority of gut bacterial genera show paradoxical associations, being reduced with US exposure and increased with fiber intake, but increased with obesity. The observed paradoxical associations are not explained by host characteristics or variation in bacterial species but might be related to potential microbial co-occurrence, as seen by positive correlations among
Roseburia
,
Prevotella
,
Dorea
, and
Coprococcus
. In the conditional analysis with mutual adjustment, including all genera associated with both obesity and US exposure in the same model, the positive associations of
Roseburia
and
Prevotella
with obesity did not persist, suggesting that their positive associations with obesity might be due to their co-occurrence and correlations with obesity-related taxa, such as
Dorea
and
Coprococcus
.
Conclusions
Among US Hispanics/Latinos, US exposure is associated with unfavorable gut microbiome profiles for obesity risk, potentially related to westernized diet during acculturation. Microbial co-occurrence could be an important factor to consider in future studies relating individual gut microbiome taxa to environmental factors and host health and disease.
Journal Article
Methodology of community-based venous blood specimen collection for the harmonized diagnostic assessment of dementia for the Longitudinal Aging Study in India (LASI-DAD): Wave 2
2025
The prevalence of dementia is on the rise, with 60% of dementia cases existing in low- and middle-income countries. In India, the prevalence was reported to be 7.4%. Since the pathophysiology of dementia is multifactorial, the Harmonized Longitudinal Aging Study in India for the Diagnostic Assessment of Dementia (LASI-DAD) collected data to capture multiple domains, including venous blood specimens (VBS). VBS collection and assays help ascertain the overall health status of an individual, understand disease pathogenesis, and diagnose diseases. In community settings, blood assays also help identify disease trends. However, community VBS collections can often be challenging. Sample quality can be impaired due to individual, environmental, geographical, and pre-analytical processing factors. Therefore, standardization of the process is imperative to ensure biomarker data of high accuracy. LASI-DAD developed a systematic sample collection, shipment, processing, and storage protocol. Multiple checkpoints were in place to monitor sample quality in real time. A phlebotomist was trained from each participating state for specimen collection. All samples were centrally tested for analytes. The overall response rate for blood collection was 71.5%. We collected 17 mL of VBS from 3,252 respondents, who consented to participate. Blood samples were tested for routine analytes, and those specific to Alzheimer’s Disease (AD) and AD-related dementias (ADRD). Data was reviewed fortnightly. The median cold chain temperature was 6.2°C and hemolysis was seen in 6.7% of the samples. LASI-DAD standardized and implemented VBS collection while overcoming the challenges faced due to India’s diverse socio-demographic, geographical, and environmental conditions. This methodology can serve as a robust tool for VBS handling and ensuring high sample quality for future community-based studies.
Journal Article
Aging measures and cancer in the Health and Retirement Study (HRS)
2025
Cancer survivors may have higher biological age (BA) than cancer-free persons (controls). In HRS, we examined the associations of BA with cancer prevalence and mortality. BA was estimated by the Klemera and Doubal method (KDM-BA), phenotypic age (PhenoAge), and subjective age (SA) among 946 cancer survivors and 4555 controls; and by epigenetic clocks (Horvath, Hannum, Levine, GrimAge, Zhang Score (ZS), and methylation-based pace of aging (mPOA)) among 582 cancer survivors and 2805 controls. Age acceleration is estimated as residuals regressed on chronological age. There are significant multivariable associations with cancer prevalence for Hannum, GrimAge, and SA, and ZS (logistic regression), and with mortality for PhenoAge, Hannum, Levine, GrimAge, and ZS in cancer survivors, and for KDM-BA, PhenoAge, and ZS in controls (Cox regression). The strongest association in cancer survivors is for GrimAge (HR per 1 SD = 1.80,
p
< 0.001). PhenoAge and first- and second-generation epigenetic clocks hold promise for predicting mortality in cancer survivors.
Cancer is known to increase biological age compared with non-cancer people of the same age. Here, the authors confirm greater biological age among cancer survivors using multiple aging constructs, and a strong association with mortality.
Journal Article
Gene expression composite scores of cellular senescence predict aging health outcomes in the Health and Retirement Study
2025
Cellular senescence, a hallmark of aging, can be quantified by the gene expression composite scores for the canonical senescence pathway (CSP), senescence initiating pathway (SIP), senescence response pathway (SRP), a summary of the three, and the SenMayo gene list; however, these have not been probed in representative populations. Using RNA sequencing data from the U.S. representative Health and Retirement Study (HRS) sample (N = 3580), we examine how these composite scores relate to sociobehavioral factors and aging-related outcomes. Senescence scores generally increase with age except for CSP. Higher scores are observed in women and individuals with class II obesity. All scores, except for CSP, are associated with accelerated epigenetic aging, physiological dysregulation, multimorbidity, cognitive decline, and 6-year mortality (all p < 0.05). These associations largely persist after adjustment for DunedinPACE. Our findings suggest that cellular senescence gene expression composite scores capture meaningful variation in aging-related health and complement existing epigenetic aging biomarkers.
Cellular senescence is an underlying mechanism of aging. Among older Americans, higher expression of genes linked to cellular senescence is seen in women and those with class II obesity, and is associated with worse health outcomes.
Journal Article