Publications by authors named "William Biggs"

We find rotating black hole solutions in the Randall-Sundrum II (RSII) model, by numerically solving a three-dimensional PDE problem using pseudospectral collocation methods. We compute the area and equatorial innermost stable orbits of these solutions. For large black holes compared with the AdS length scale ℓ the black hole exhibits four-dimensional behavior, approaching the Kerr metric on the brane, while for small black holes, the solution tends instead towards a five-dimensional Myers-Perry black hole with a single nonzero rotation parameter aligned with the brane.

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Objective: To explore the effect of discontinuing continuous glucose monitoring (CGM) after 8 months of CGM use in adults with type 2 diabetes treated with basal without bolus insulin.

Research Design And Methods: This multicenter trial had an initial randomization to either real-time CGM or blood glucose monitoring (BGM) for 8 months followed by 6 months in which the BGM group continued to use BGM ( = 57) and the CGM group was randomly reassigned either to continue CGM ( = 53) or discontinue CGM with resumption of BGM for glucose monitoring ( = 53).

Results: In the group that discontinued CGM, mean time in range (TIR) 70-180 mg/dL, which improved from 38% before initiating CGM to 62% after 8 months of CGM, decreased after discontinuing CGM to 50% at 14 months (mean change from 8 to 14 months -12% [95% CI -21% to -3%], = 0.

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Importance: Continuous glucose monitoring (CGM) has been shown to be beneficial for adults with type 2 diabetes using intensive insulin therapy, but its use in type 2 diabetes treated with basal insulin without prandial insulin has not been well studied.

Objective: To determine the effectiveness of CGM in adults with type 2 diabetes treated with basal insulin without prandial insulin in primary care practices.

Design, Setting, And Participants: This randomized clinical trial was conducted at 15 centers in the US (enrollment from July 30, 2018, to October 30, 2019; follow-up completed July 7, 2020) and included adults with type 2 diabetes receiving their diabetes care from a primary care clinician and treated with 1 or 2 daily injections of long- or intermediate-acting basal insulin without prandial insulin, with or without noninsulin glucose-lowering medications.

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Therapeutic inertia and suboptimal treatment adherence remain the key drivers of chronic poor diabetes control. Advances in mHealth technologies have spurred the development of a new generation of blood glucose monitoring systems that enable individuals with diabetes to automatically transfer glucose data and other information from their smartphones to their health care providers for analysis and interpretation via diabetes data-management software. This report discusses key lessons learned from two investigations that assessed the effects of interventions using the Accu-Chek Connect diabetes-management system (Roche Diabetes Care, Indianapolis, Ind.

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Article Synopsis
  • Diatoms are crucial for ocean ecology, contributing over 40% of marine primary productivity by linking silicon and carbon cycles.
  • Limited silicon (Si) availability increases viral infections and mortality in diatom populations, particularly in coastal waters of the California Current Ecosystem.
  • Research shows that Si stress in diatoms promotes early stages of viral infection, highlighting the significant role of viruses in diatom health and their impact on biogeochemical cycles.
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  • Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a potential cure for blood cancers but is limited by complications like graft-versus-host disease (GVHD).
  • A study involving 205 acute myeloid leukemia patients identified minimal genetic factors linked to acute GVHD, indicating that further research is needed to understand other genetic influences beyond major histocompatibility complex (HLA) matching.
  • Notably, specific Y-chromosome genetic variations in males receiving transplants from female donors were associated with acute GVHD, suggesting potential implications for future genomic research and applications in related fields like cancer immunotherapy and organ transplants.
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Reducing premature mortality associated with age-related chronic diseases, such as cancer and cardiovascular disease, is an urgent priority. We report early results using genomics in combination with advanced imaging and other clinical testing to proactively screen for age-related chronic disease risk among adults. We enrolled active, symptom-free adults in a study of screening for age-related chronic diseases associated with premature mortality.

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Urine culture and microscopy techniques are used to profile the bacterial species present in urinary tract infections. To gain insight into the urinary flora, we analyzed clinical laboratory features and the microbial metagenome of 121 clean-catch urine samples. 16S rDNA gene signatures were successfully obtained for 116 participants, while metagenome sequencing data was successfully generated for samples from 49 participants.

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Understanding the significance of genetic variants in the noncoding genome is emerging as the next challenge in human genomics. We used the power of 11,257 whole-genome sequences and 16,384 heptamers (7-nt motifs) to build a map of sequence constraint for the human species. This build differed substantially from traditional maps of interspecies conservation and identified regulatory elements among the most constrained regions of the genome.

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Objectives: Inflammatory bowel diseases (IBD), comprised of Crohn's disease (CD) and ulcerative colitis (UC), are characterized by a complex pathophysiology that is thought to result from an aberrant immune response to a dysbiotic luminal microbiota in genetically susceptible individuals. New technologies support the joint assessment of host-microbiome interaction.

Methods: Using whole genome sequencing and shotgun metagenomics, we studied the clinical features, host genome, and stool microbial metagenome of 85 IBD patients, and compared the results to 146 control individuals.

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Short tandem repeats (STRs) are hyper-mutable sequences in the human genome. They are often used in forensics and population genetics and are also the underlying cause of many genetic diseases. There are challenges associated with accurately determining the length polymorphism of STR loci in the genome by next-generation sequencing (NGS).

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The HLA gene complex on human chromosome 6 is one of the most polymorphic regions in the human genome and contributes in large part to the diversity of the immune system. Accurate typing of HLA genes with short-read sequencing data has historically been difficult due to the sequence similarity between the polymorphic alleles. Here, we introduce an algorithm, xHLA, that iteratively refines the mapping results at the amino acid level to achieve 99-100% four-digit typing accuracy for both class I and II HLA genes, taking only [Formula: see text]3 min to process a 30× whole-genome BAM file on a desktop computer.

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The presence of advanced fibrosis in nonalcoholic fatty liver disease (NAFLD) is the most important predictor of liver mortality. There are limited data on the diagnostic accuracy of gut microbiota-derived signature for predicting the presence of advanced fibrosis. In this prospective study, we characterized the gut microbiome compositions using whole-genome shotgun sequencing of DNA extracted from stool samples.

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In this study, we used whole-genome sequencing and gene expression profiling of 215 human induced pluripotent stem cell (iPSC) lines from different donors to identify genetic variants associated with RNA expression for 5,746 genes. We were able to predict causal variants for these expression quantitative trait loci (eQTLs) that disrupt transcription factor binding and validated a subset of them experimentally. We also identified copy-number variant (CNV) eQTLs, including some that appear to affect gene expression by altering the copy number of intergenic regulatory regions.

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Induced pluripotent stem cells (iPSCs) show variable methylation patterns between lines, some of which reflect aberrant differences relative to embryonic stem cells (ESCs). To examine whether this aberrant methylation results from genetic variation or non-genetic mechanisms, we generated human iPSCs from monozygotic twins to investigate how genetic background, clone, and passage number contribute. We found that aberrantly methylated CpGs are enriched in regulatory regions associated with MYC protein motifs and affect gene expression.

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The characterization of the blood virome is important for the safety of blood-derived transfusion products, and for the identification of emerging pathogens. We explored non-human sequence data from whole-genome sequencing of blood from 8,240 individuals, none of whom were ascertained for any infectious disease. Viral sequences were extracted from the pool of sequence reads that did not map to the human reference genome.

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Genetic factors modifying the blood metabolome have been investigated through genome-wide association studies (GWAS) of common genetic variants and through exome sequencing. We conducted a whole-genome sequencing study of common, low-frequency and rare variants to associate genetic variations with blood metabolite levels using comprehensive metabolite profiling in 1,960 adults. We focused the analysis on 644 metabolites with consistent levels across three longitudinal data collections.

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We report on the sequencing of 10,545 human genomes at 30×-40× coverage with an emphasis on quality metrics and novel variant and sequence discovery. We find that 84% of an individual human genome can be sequenced confidently. This high-confidence region includes 91.

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As reports on possible associations between microbes and the host increase in number, more meaningful interpretations of this information require an ability to compare data sets across studies. This is dependent upon standardization of workflows to ensure comparability both within and between studies. Here we propose the standard use of an alternate collection and stabilization method that would facilitate such comparisons.

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Observations from human microbiome studies are often conflicting or inconclusive. Many factors likely contribute to these issues including small cohort sizes, sample collection, and handling and processing differences. The field of microbiome research is moving from 16S rDNA gene sequencing to a more comprehensive genomic and functional representation through whole-genome sequencing (WGS) of complete communities.

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Objective: To develop an assay for vaginal CA125 and determine if vaginal levels correlate with the phase of the menstrual cycle.

Study Design: Fifteen women through a total of 20 ovulatory cycles obtained daily vaginal swabs for assay. Sampling began within the first 3 days after menses in and continued into the luteal phase.

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Article Synopsis
  • Coronary heart disease (CHD) is still a widespread issue, leading researchers to create a new risk assessment algorithm called CHDRA, aimed at better evaluation for individuals at intermediate risk.
  • The CHDRA includes a series of biomarker assays tested in a clinical lab to check their performance in terms of accuracy, sensitivity, and reproducibility.
  • Results show that the CHDRA assays perform well, with consistency across different tests and minimal impact from common laboratory variables, indicating a reliable tool for assessing CHD risk.
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  • Aviir, Inc. is a biotech company focused on creating lab tests to help prevent cardiovascular diseases and metabolic syndromes through personalized information for doctors and patients.
  • They developed MIRISK VP™, a test designed to assess the risk of heart attacks in individuals.
  • Aviir also aims to enhance its genomic testing capabilities to identify inherited cardiovascular issues, combining various diagnostic tools for a complete health solution.
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