Harmonization of four biomarkers across nine nationally representative studies of older persons.

Introduction: A growing number of international population surveys have included measurement of biomarkers, but differ in the type of specimens collected, sample processing procedures, shipment protocols, and laboratory assay platforms. The purpose of this study is to harmonize biomarker data from nine nationally representative studies of people 50 years of age and over by adjusting for assay platforms and type of specimens for total cholesterol (total-C), high-density lipoprotein cholesterol (HDL-C), glycosylated hemoglobin (HbA1c), and C-reactive protein (CRP).

Methods: Sets of 24 identical serum, plasma, whole blood, and dried blood spot harmonization samples with known analyte levels were generated at a reference laboratory, shipped at -80°C to the respective study laboratories, and subsequently assayed following the study laboratory's protocol.

Dried blood spot collection, sample quality, and fieldwork conditions: Structural validations for conversion into standard values.

Objectives: SHARE, a pan-European panel study in 27 European countries and Israel, has collected dried blood spot (DBS) samples from approximately 27 000 respondents in 13 countries. We aim to obtain factors to convert analyte values between DBS and venous blood samples (VBS) taking account of adverse fieldwork conditions such as small spot size, high temperature and humidity, short drying time and long shipment times.

Methods: We obtained VBS and DBS from a set of 20 donors in a laboratory setting, and treated the DBS in a systematic and controlled fashion simulating SHARE fieldwork conditions.

Dried blood spots: Effects of less than optimal collection, shipping time, heat, and humidity.

Objectives: This study investigates how factors related to collection, storage, transport time, and environmental conditions affect the quality and accuracy of analyses of dried blood spot (DBS) samples.

Methods: Data come from the 2016 Health and Retirement Study (HRS) DBS laboratory reports and the HRS merged with the National Climatic Data Center (NCDC) Global Historical Climate Network Daily (NCDC GHCN-Daily) and the NCDC Local Climatological Data, by zip code. We ran regression models to examine the associations between assay values based on DBS for five analytes (total cholesterol, high-density lipoprotein (HDL) cholesterol, glycosylated hemoglobin (HbA1c), C-reactive protein (CRP), and cystatin C) and the characteristics of DBS cards and drops, shipping time, and temperature, and humidity at the time of collection.

HPLC-based Measurement of Glycated Hemoglobin using Dried Blood Spots Collected under Adverse Field Conditions.

Glycated hemoglobin (HbA1c) measured using high-performance liquid chromatography (HPLC) assays with venous blood and dried blood spots (DBS) are compared for 143 paired samples collected in Aceh, Indonesia. Relative to gold-standard venous-blood values, DBS-based values reported by the HPLC are systematically upward biased for HbA1c<8% and the fraction diabetic (HbA1c ≥ 6.5%) is overstated almost five-fold.

The metabolic syndrome and mammographic breast density in a racially diverse and predominantly immigrant sample of women.

Purpose: The metabolic syndrome [MetS, clustering of elevated blood pressure, triglycerides and glucose, reduced high-density lipoprotein cholesterol (HDL-C), abdominal obesity] has been associated with increased breast cancer risk, but less is known about its association with mammographic breast density, a strong risk factor for breast cancer.

Methods: We collected data on risk factors, body size, and blood pressure via in-person interviews and examinations and measured glucose, triglycerides, and HDL-C from dried blood spots from women recruited through a mammography screening clinic (n = 373; 68 % Hispanic, 17 % African-American, 63 % foreign born). We performed linear regression models to examine the associations of each MetS component and the MetS cluster (≥3 components) with percent density and dense breast area, measured using a computer-assisted technique and Cumulus software.

Use of a commercial ELISA for the detection of measles-specific immunoglobulin G (IgG) in dried blood spots collected from children living in low-resource settings.

Seroepidemiological monitoring of population immunity to vaccine-preventable diseases is critical to prevent future outbreaks. Dried blood spots (DBS), drops of capillary blood dried on filter paper, are an affordable, minimally invasive alternative to venipuncture for collecting blood in field settings. However, few proven methods exist to analyze DBS for the presence of protective antibodies.

Validation and modification of dried blood spot-based glycosylated hemoglobin assay for the longitudinal aging study in India.

Objectives: This study aims to validate a modified dried blood spot (DBS)-based glycosylated hemoglobin (HbA1c) assay protocol, after a pretest in India showed poor correlation between the original DBS-based protocol and venous results.

Methods: The original protocol was tested on different chemistry analyzers and then simplified at the University of Washington (UW). A second pretest was conducted in India to validate the modified assay protocol, using 44 quality control specimens.

Blood spot-based measures of glucose homeostasis and diabetes prevalence in a nationally representative population of young US adults.

Purpose: We investigated understudied biomarker-based diabetes among young US adults, traditionally characterized by low cardiovascular disease risk.

Methods: We examined 15,701 participants aged 24 to 32 years at Wave IV of the National Longitudinal Study of Adolescent Health (Add Health, 2008). The study used innovative and relatively noninvasive methods to collect capillary whole blood via finger prick at in-home examinations in all 50 states.

Flow cytometric analysis of fluorescence in situ hybridization with dye dilution and DNA staining (flow-FISH-DDD) to determine telomere length dynamics in proliferating cells.

Background: Telomeres shorten during DNA replication; extensive erosion of telomeres likely promotes replicative senescence and chromosomal instability. Telomere length in individual cells has been quantified by flow cytometric analysis of fluorescence in situ hybridization (flow-FISH). To determine the rate of telomere attrition (telomere erosion per cell division), we combined flow-FISH with dye dilution and DNA staining (flow-FISH-DDD) and measured telomere-specific fluorescence in proliferating cells identified by cell generation and cell cycle phase.

The cell cycle phases of DNA damage and repair initiated by topoisomerase II-targeting chemotherapeutic drugs.

Although cytostasis and cytotoxicity induced by cancer chemotherapy drugs targeting topoisomerase II (topoII) arise in specific cell cycle phases, it is unknown whether the drug-initiated DNA damage triggering these responses, or the repair (reversal) of this damage, differs between cell cycle phases or between drug classes. Accordingly, we used a flow cytometric alkaline unwinding assay to measure DNA damage (strand breakage (SB)) and SB repair in each cell cycle compartment of human cancer cell lines treated with clinically relevant concentrations of doxorubicin, daunomycin, etoposide, and mitoxantrone. We found that treated HeLa and A549 cells exhibited the greatest SB in G2/M phase, the least in G1 phase, and generally an intermediate amount in S phase.

Flow cytometric analysis of the cell cycle phase specificity of DNA damage induced by radiation, hydrogen peroxide and doxorubicin.

We have optimized a flow cytometric DNA alkaline unwinding assay to increase the sensitivity in detecting low levels of DNA damage (strand breaks and alkali-labile sites) and to permit the measurement of the extent of DNA damage within each cell cycle compartment. The lowest gamma radiation dose that induced detectable DNA damage in each cell cycle phase of HeLa and CEM cells was 10 cGy. The lowest H(2)O(2) concentration that induced detectable DNA damage in each cell cycle phase was 0.