Publications by authors named "Ruth A Johnson"

Progression of virtually all forms of chronic kidney disease (CKD) is associated with activation of pro-inflammatory and pro-fibrotic signaling pathways. Despite extensive research, progress in identifying therapeutic targets to arrest or slow progression of CKD has been limited by incomplete understanding of basic mechanisms underlying renal inflammation and fibrosis in CKD. Recent studies have identified Kruppel-like transcription factors that have been shown to play critical roles in renal development, homeostasis, and response to injury.

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Telomere length (TL) is associated with cardiovascular disease (CVD) and cancer. Obstructive sleep apnea (OSA) is also linked to higher risk of CVD and cancer, and to TL. We investigated the association between TL and risk of major adverse cardiac events (MACE) and cancer in OSA patients.

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Obstructive sleep apnea (OSA) is associated with cardiometabolic diseases. Telomere shortening is linked to hypertension, diabetes mellitus, and cardiovascular diseases. Because these conditions are highly prevalent in OSA, we hypothesized that telomere length (TL) would be reduced in OSA patients.

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An important determinant of the pathogenesis and prognosis of various diseases is inherited genetic variation. Single-nucleotide polymorphisms (SNPs), variations at a single base position, have been identified in both protein-coding and noncoding DNA sequences, but the vast majority of millions of those variants are far from being functionally understood. Here we show that a common variant in the gene MTHFR [rs1801133 (C>T)] not only influences response to neoadjuvant chemoradiotherapy in patients with rectal cancer, but it also influences recurrence of the disease itself.

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Peripheral blood telomere length has been associated with age-related conditions including Alzheimer's disease (AD). This suggests that telomere length may identify subjects at increased risk of AD. Thus, we investigated the associations of peripheral blood telomere length with amnestic mild cognitive impairment (aMCI), a putative precursor of AD, among Mayo Clinic Study of Aging participants who were prospectively followed for incident aMCI.

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Objectives: Telomeres are nucleoprotein structures that cap the end of chromosomes and shorten with sequential cell divisions in normal aging. Short telomeres are also implicated in the incidence of many cancers, but the evidence is not conclusive for colorectal cancer (CRC). Therefore, the aim of this study was to assess the association of CRC and telomere length.

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Introduction: Colorectal cancer (CRC) tumor DNA is characterized by chromosomal damage termed chromosomal instability (CIN) and excessively shortened telomeres. Up to 80% of CRC is microsatellite stable (MSS) and is historically considered to be chromosomally unstable (CIN+). However, tumor phenotyping depicts some MSS CRC with little or no genetic changes, thus being chromosomally stable (CIN-).

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Background: Both shorter and longer telomeres in peripheral blood leukocyte (PBL) DNA have been associated with cancer risk. However, associations remain inconsistent across studies of the same cancer type. This study compares DNA preparation methods to determine telomere length from patients with colorectal cancer.

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Background: Telomeres, the ends of chromosomes, are critical for maintaining genomic stability and grow shorter with age. Shortened telomeres in pancreatic tissue play a key role in the pathogenesis of pancreatic cancer, and shorter telomeres in peripheral blood leukocytes (PBL) have been associated with increased risk for several cancer types. We hypothesized that shorter blood telomeres are associated with higher risk for pancreatic cancer.

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Background: Colorectal cancer (CRC) can be prevented by the early detection and removal of advanced adenomas (AAs) by colonoscopy. Our aim was to evaluate peripheral blood leukocyte (PBL) telomere length as a potential biomarker for the presence of AAs.

Methods: PBL telomere length was measured in patients with AAs (n=35), in a control group of similarly aged patients who had a normal colonoscopy (n=145) and in a separate population group with no history of cancer, again similarly aged (n=495).

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The autosomal recessive polycystic kidney disease (ARPKD) gene, PKHD1, has been implicated in the genesis or growth of colorectal adenocarcinoma, as a high level of somatic mutations was found in colorectal tumor tissue. To determine whether carriers of a single PKHD1 mutation are at increased risk of colorectal carcinoma, we assessed the prevalence of the commonest European mutation, T36M. First, we assayed a European cohort of ARPKD patients and found T36M was responsible for 13.

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MUTYH adenomatous polyposis (MAP) can mimic both the familial adenomatous polyposis (FAP) and hereditary nonpolyposis colon cancer (HNPCC) phenotypes. As a result of MAP's phenotypic overlap with FAP, some DNA diagnostic laboratories perform MUTYH testing in conjunction with APC testing in patients with suspected FAP or attenuated FAP (AFAP). In addition to testing FAP/AFAP samples for MUTYH mutations, we were interested whether there would also be value in testing samples referred for HNPCC testing.

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Purpose: Colorectal carcinoma (CRC) can be divided into two nonoverlapping groups: those that are chromosomally unstable but microsatellite stable (MSS CIN+) and those that are chromosomally stable but microsatellite unstable (MSI CIN-). However, a third group with neither chromosome nor microsatellite instability (MSS CIN-) makes a substantial contribution to the total CRC burden. The clinicopathologic features of MSS CIN- CRC are not well delineated.

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Background/aims: Defective DNA mismatch repair (MMR) in pancreatic cancer, reported in up to 13% of sporadic pancreatic cancers, may predict a good prognosis. To determine if long-term survival in pancreatic cancer could be attributed to defective DNA MMR, we ascertained its prevalence in 35 pancreatic cancer patients who survived > or =3 years after surgery.

Methods: We performed immunohistochemistry (IHC) for MMR proteins hMLH1, hMSH2, and hMSH6 in all 35 tumors and microsatellite instability (MSI) studies in 34/35 tumors using 10 microsatellite markers in paired normal and tumor DNA.

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Background & Aims: MYH-associated polyposis is a recently described disease that is characterized by multiple colorectal adenomas and a recessive pattern of inheritance. Individuals with MYH-associated polyposis have biallelic mutations in MYH, a base excision repair gene, and are negative for germline mutations in the APC gene. In this study, the 2 most prevalent MYH mutations in white persons, Y165C and G382D, were analyzed for their presence in 984 subjects selected from 3 groups: 400 undergoing screening colonoscopy and found to have 0-3 polyps, 444 with colorectal cancer (CRC), and 140 referred for APC mutation analysis in which a germline mutation was not identified.

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