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Full-Text Articles in Medicine and Health Sciences
Association Between Bilirubin And Cardiovascular Disease Risk Factors: Using Mendelian Randomization To Assess Causal Inference, Patrick F. Mcardle, Brian W. Whitcomb, Keith Tanner, Braxton D. Mitchell, Alan R. Shuldiner, Afshin Parsa
Association Between Bilirubin And Cardiovascular Disease Risk Factors: Using Mendelian Randomization To Assess Causal Inference, Patrick F. Mcardle, Brian W. Whitcomb, Keith Tanner, Braxton D. Mitchell, Alan R. Shuldiner, Afshin Parsa
Brian W. Whitcomb
Background: Elevated serum bilirubin has been associated with reduced risk of cardiovascular disease (CVD). However, serum bilirubin is also related with several potential confounders related to CVD, such as obesity. Mendelian randomization has been proposed as a method to address challenges to validity from confounding and reverse causality. It utilizes genotype to estimate causal relationships between a gene product and physiological outcomes. In this report, we demonstrate its use in assessing direct causal relations between serum bilirubin levels and CVD risk factors, including obesity, cholesterol, measures of vascular function and blood pressure. Methods: Study subjects included 868 asymptomatic individuals. Study …
Contribution Of Male Age To Outcomes In Assisted Reproductive Technologies—Addressing Methodological Challenges, Brian W. Whitcomb, Eric D. Levens, Renée Turzanski-Fortner, Kevin S. Richter, Simon Kipersztok, Robert J. Stillman, Michael J. Levy
Contribution Of Male Age To Outcomes In Assisted Reproductive Technologies—Addressing Methodological Challenges, Brian W. Whitcomb, Eric D. Levens, Renée Turzanski-Fortner, Kevin S. Richter, Simon Kipersztok, Robert J. Stillman, Michael J. Levy
Brian W. Whitcomb
Objective—To evaluate the relation between male age and pregnancy outcome in donor oocyte assisted reproductive technology cycles Design—Retrospective cohort Setting—Private IVF center. Patients—1392 donor cycles from 1083 female recipients and their male partners Interventions—Oocyte donor cycles Main outcome measure(s)—Live birth Results—Increasing male age was associated with semen parameters including volume and motility; however, male age was not observed to have a statistically significant association with likelihood of live birth in donor cycles after adjustment for female recipient age. Conclusions—When treatment cycle number and female recipient age were taken into account, male age had no significant association with pregnancy outcomes in …
Realignment And Multiple Imputation Of Longitudinal Data: An Application To Menstrual Cycle Data, Sunni L. Mumford, Enrique F. Schisterman, Audrey J. Gaskinsa, Anna Z. Pollack, Neil J. Perkins, Brian W. Whitcomb, Aijun Ye, Jean Wactawski-Wende
Realignment And Multiple Imputation Of Longitudinal Data: An Application To Menstrual Cycle Data, Sunni L. Mumford, Enrique F. Schisterman, Audrey J. Gaskinsa, Anna Z. Pollack, Neil J. Perkins, Brian W. Whitcomb, Aijun Ye, Jean Wactawski-Wende
Brian W. Whitcomb
Reproductive hormone levels are highly variable among premenopausal women during the menstrual cycle. Accurate timing of hormone measurement is essential, especially when investigating day- or phase-specific effects. The BioCycle Study used daily urine home fertility monitors to help detect the luteinising hormone (LH) surge in order to schedule visits with biologically relevant windows of hormonal variability. However, as the LH surge is brief and cycles vary in length, relevant hormonal changes may not align with scheduled visits even when fertility monitors are used. Using monitor data, measurements were reclassified according to biological phase of the menstrual cycle to more accurate …
Ovarian Function And Cigarette Smoking In The Biocycle Study, Brian W. Whitcomb, Sara D. Bodach, Sunni L. Mumford, Neil J. Perkins, Maurizio Trevisan, Jean Wactawski-Wende, Aiyi Liu, Enrique F. Schisterman
Ovarian Function And Cigarette Smoking In The Biocycle Study, Brian W. Whitcomb, Sara D. Bodach, Sunni L. Mumford, Neil J. Perkins, Maurizio Trevisan, Jean Wactawski-Wende, Aiyi Liu, Enrique F. Schisterman
Brian W. Whitcomb
Cigarette smoking has been implicated in reproductive outcomes including delayed conception, but mechanisms underlying these associations remain unclear. One potential mechanism is the effect of cigarette smoking on reproductive hormones; however, studies evaluating associations between smoking and hormone levels are complicated by variability of hormones and timing of specimen collection. We evaluated smoking among women participating in the BioCycle Study, a longitudinal study of menstrual cycle function in healthy, premenopausal, regularly menstruating women (n = 259). Fertility monitors were used to help guide timing of specimen collection. Serum levels of oestradiol, progesterone, follicle-stimulating hormone (FSH), luteinising hormone (LH) and total …
Treatment Of Batch In The Detection, Calibration, And Quantification Of Immunoassays In Large-Scale Epidemiologic Studies, Brian W. Whitcomb, Neil J. Perkins, Paul S. Albert, Enrique F. Schisterman
Treatment Of Batch In The Detection, Calibration, And Quantification Of Immunoassays In Large-Scale Epidemiologic Studies, Brian W. Whitcomb, Neil J. Perkins, Paul S. Albert, Enrique F. Schisterman
Brian W. Whitcomb
Many laboratory assays measure biomarkers via a 2-stage process. Direct measurement yields relative measures that are subsequently transformed to the unit of interest by using a calibration experiment. The calibration experiment is performed within the main experiment and uses a validation set for which true values are known and relative values are measured by assays to estimate the relation between relative and absolute values. Immunoassays, polymerase chain reaction, and chromatographic approaches are among assays performed in this manner. METHODS: For studies with multiple batches, data from more than a single calibration experiment are available. Conventionally, calibration of assays based on …
Effects Of Low-Dose Aspirin In In-Vitro Fertilization, Enrique F. Schisterman, Audrey J. Gaskins, Brian W. Whitcomb
Effects Of Low-Dose Aspirin In In-Vitro Fertilization, Enrique F. Schisterman, Audrey J. Gaskins, Brian W. Whitcomb
Brian W. Whitcomb
Purpose of review—In theory, use of aspirin in IVF is based on its anti-inflammatory, vasodilatory, and platelet aggregation inhibition properties, which improve blood flow to a woman's implantation site. It is hypothesized that this effect on blood flow will improve success rates. Recent findings—Clinical studies investigating the use of low-dose aspirin (LDA) as an adjuvant therapy to IVF have produced conflicting results. The conflicting results have come as a consequence of the heterogeneous mixture of clinical trials with lack of adequate power. Even after multiple metaanalyses, differing estimates of effect were calculated as to whether aspirin should be used in …
Microdose Follicular Flare: A Viable Alternative For Normal Responding Patients Undergoing In Vitro Fertilization?, Eric D. Levensa, Brian W. Whitcomb, Jonathan D. Kortc, Donna Materia-Hoovere, Frederick W. Larsena
Microdose Follicular Flare: A Viable Alternative For Normal Responding Patients Undergoing In Vitro Fertilization?, Eric D. Levensa, Brian W. Whitcomb, Jonathan D. Kortc, Donna Materia-Hoovere, Frederick W. Larsena
Brian W. Whitcomb
Objective—To compare cycle outcomes among normal responding patients ≤30 years receiving microdose follicular flare (MDF) and long-luteal agonist (LL). Design—Retrospective cohort study. Setting—Military-based ART center. Patients—First, autologous ART cycles among 499 women ≤30 years old from 01/1999 to 12/2005. Interventions—Following OCP administration prior to cycle start, patients were non-randomly assigned to either LL or MDF for LH surge suppression. LL received 1 mg/d leuprolide acetate (LA) on cycle day 21, which was reduced to 0.25 mg/day 10–14 days later. MDF received LA (40 μg BID) beginning 3 days after discontinuing OCPs. Both groups received a combination of hMG and rFSH. …
Ovarian Follicular Flushing Among Low Responding Art Patients, Eric D. Levens, Brian W. Whitcomb, Mark D. Payson, Frederick W. Larsen
Ovarian Follicular Flushing Among Low Responding Art Patients, Eric D. Levens, Brian W. Whitcomb, Mark D. Payson, Frederick W. Larsen
Brian W. Whitcomb
A randomized comparison trial was performed to evaluate whether follicular reaspiration with use of a double-lumen retrieval needle improves oocyte recovery when compared with direct follicular aspiration among low-responding patients undergoing ART. There were no differences observed in the number of oocytes retrieved (single lumen: 6.5 +/- 2.2 oocytes, double lumen: 7.2 +/- 2.3 oocytes) whereas follicular reaspiration with the double-lumen retrieval needle resulted in a twofold increase in procedure time.
Z-Scores And The Birthweight Paradox, Enrique F. Schisterman, Brian W. Whitcomb, Sunni L. Mumford, Robert W. Platt
Z-Scores And The Birthweight Paradox, Enrique F. Schisterman, Brian W. Whitcomb, Sunni L. Mumford, Robert W. Platt
Brian W. Whitcomb
Investigators have long puzzled over the observation that low-birthweight babies of smokers tend to fare better than low-birthweight babies of non-smokers. Similar observations have been made with regard to factors other than smoking status, including socio-economic status, race and parity. Use of standardised birthweights, or birthweight z-scores, has been proposed as an approach to resolve the crossing of the curves that is the hallmark of the so-called birthweight paradox. In this paper, we utilise directed acyclic graphs, analytical proofs and an extensive simulation study to consider the use of z-scores of birthweight and their effect on statistical analysis. We illustrate …
Circulating Levels Of Cytokines During Pregnancy; Thrombopoietin Is Elevated In Miscarriage, Brian W. Whitcomb, Enrique F. Schisterman, Mark A. Klebanoff, Mona Baumgarten, Xiaoping Luo, Nasser Chegini
Circulating Levels Of Cytokines During Pregnancy; Thrombopoietin Is Elevated In Miscarriage, Brian W. Whitcomb, Enrique F. Schisterman, Mark A. Klebanoff, Mona Baumgarten, Xiaoping Luo, Nasser Chegini
Brian W. Whitcomb
Objective To evaluate the hypothesis that cytokine levels are associated with miscarriage risk using serum samples collected prior to report of miscarriage. Design A nested case-control study. Setting Biospecimens from the multi-site Collaborative Perinatal Project, University of Florida laboratory assessment of IL-1ra, IL-1β, IL-4, IL-6, IFN-γ, TNF-α, TPO and G-CSF. Patients were obtained from cases of miscarriage (N=439) matched to controls (N=373) by gestational age (GA) at sample collection. Intervention None. Main outcome measures Miscarriage. Results Increased risk of miscarriage was associated with elevated TPO (AOR: 1.16, 95% confidence interval (CI):1.00 – 1.36) and decreased G-CSF (AOR: 0.78, 95% CI …
Blastocyst Development Rate Impacts Outcome In Cryopreserved Blastocyst Transfer Cycles, Eric D. Levens, Brian W. Whitcomb, Sasha Hennessy, Aidita N. James, Belinda J. Yauger, Frederick W. Larsena
Blastocyst Development Rate Impacts Outcome In Cryopreserved Blastocyst Transfer Cycles, Eric D. Levens, Brian W. Whitcomb, Sasha Hennessy, Aidita N. James, Belinda J. Yauger, Frederick W. Larsena
Brian W. Whitcomb
Objective To assess cycle outcome among day 5 and day 6 cryopreserved frozen-thawed blastocyst embryo transfers (FBET). Design Retrospective cohort study. Setting Military-based ART center. Patients One hundred seventy-two non-donor, programmed cryopreserved embryo cycles. Interventions Fully expanded blastocysts on day 5 were cryopreserved on day 5 and those achieving this state on day 6 were cryopreserved on day 6. Leuprolide acetate was given for ovulation inhibition and endometrial supplementation was by oral and vaginal estradiol. Progesterone in oil was administered and blastocyst transfer occurred in the morning of the 6th day of progesterone. Main Outcome Measures Implantation, pregnancy and live …
Evidence Of Absence Or Absence Of Evidence? A Re-Analysis Of The Effects Of Low-Dose Aspirin In Ivf, Marcus D. Ruopp, Tara C. Collins, Brian W. Whitcomb, Enrique F. Schisterman
Evidence Of Absence Or Absence Of Evidence? A Re-Analysis Of The Effects Of Low-Dose Aspirin In Ivf, Marcus D. Ruopp, Tara C. Collins, Brian W. Whitcomb, Enrique F. Schisterman
Brian W. Whitcomb
Objective—To assess the conflicting evidence whether low-dose aspirin (LDA) is beneficial in invitro fertilization (IVF), and evaluate the meta-analysis performed by Gelbaya et al. in the March 2007 issue of Human Reproduction Update, in which they found no effects of LDA and recommended discontinuing its use in IVF. We present a re-analysis of the effects of LDA in IVF and raise methodological questions regarding the analysis by Gelbaya et al. Design—A meta-analysis of prospective randomized trials evaluating the effects of low-dose aspirin in IVF. Patients—Women undergoing in-vitro fertilization/intracytoplasmic sperm injection Interventions—Low-dose acetylsalicylic acid (aspirin) Main Outcome Measure(s)—Pregnancy rates, implantation rates, …
Assays With Lower Detection Limits: Implications For Epidemiological Investigations, Brian W. Whitcomb, Enrique F. Schisterman
Assays With Lower Detection Limits: Implications For Epidemiological Investigations, Brian W. Whitcomb, Enrique F. Schisterman
Brian W. Whitcomb
No abstract provided.
The Limitations Due To Exposure Detection Limits For Regression Models, Enrique F. Schisterman, Albert Vexler, Brian W. Whitcomb, Aiyi Liu
The Limitations Due To Exposure Detection Limits For Regression Models, Enrique F. Schisterman, Albert Vexler, Brian W. Whitcomb, Aiyi Liu
Brian W. Whitcomb
Biomarker use in exposure assessment is increasingly common and consideration of related issues is of growing importance. Exposure quantification may be compromised when measurement is subject to a lower threshold. Statistical modeling of such data requires a decision regarding the handling of such readings. Various authors have considered this problem. In the context of linear regression analysis, Richardson and Ciampi proposed replacement of data below a threshold by a constant equal to the expectation for such data to yield unbiased estimates. Use of such an imputation has some limitations; distributional assumptions are required, and bias reduction in estimation of regression …
Coronary Age As A Risk Factor In The Modified Framingham Risk Score, Enrique F. Schisterman, Brian W. Whitcomb
Coronary Age As A Risk Factor In The Modified Framingham Risk Score, Enrique F. Schisterman, Brian W. Whitcomb
Brian W. Whitcomb
Background: Clinical guidelines emphasize risk assessment as vital to patient selection for medical primary intervention. However, risk assessment methods are restricted in their ability to predict further coronary events. The most widely accepted tool in the United States is the Framingham risk score. In these equations age is a powerful risk factor. Although the extent of coronary atherosclerosis increases with age, there is large inter-individual variability in the rate of development and progression of this disease. This fact limits the utility of Framingham scoring when applied to individuals. Electron beam tomography (EBT), which measures coronary calcium, provides a non-invasive method …