Publications by authors named "Tyler D Johnson"

Prepubertal obesity is growing at an alarming rate and is now considered a risk factor for renal injury. Recently, we reported that the early development of renal injury in obese Dahl salt-sensitive (SS) leptin receptor mutant (SS LepR mutant) rats was associated with increased T-cell infiltration and activation before puberty. Therefore, the current study investigated the effect of inhibiting T-cell activation with abatacept on the progression of renal injury in young obese SS LepR mutant rats before puberty.

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Article Synopsis
  • The study examines how redox conditions in groundwater influence the movement of nutrients and contaminants, which can impact human health, highlighting the importance of understanding these conditions across large areas like the contiguous United States.* -
  • Using a machine learning technique called random forest classification, researchers predicted groundwater redox conditions by analyzing data from over 30,000 wells and identified significant factors like geology, soil properties, and hydrologic position that affect oxic (oxygen-rich) conditions.* -
  • The findings indicate that the likelihood of having oxic groundwater is closely related to factors like stream proximity, depth from the water table, base flow index, and topographic wetness index, suggesting how water movement and soil characteristics play a role in oxygen levels in
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Prepubertal obesity is currently an epidemic and is considered as a major risk factor for renal injury. Previous studies have demonstrated that insulin resistance contributes to renal injury in obesity, independent of diabetes. However, studies examining the relationship between insulin resistance and renal injury in obese children are lacking.

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In 2019, 254 samples were collected from five aquifer systems to evaluate perfluoroalkyl and polyfluoroalkyl substance (PFAS) occurrence in groundwater used as a source of drinking water in the eastern United States. The samples were analyzed for 24 PFAS, major ions, nutrients, trace elements, dissolved organic carbon (DOC), volatile organic compounds (VOCs), pharmaceuticals, and tritium. Fourteen of the 24 PFAS were detected in groundwater, with 60 and 20% of public-supply and domestic wells, respectively, containing at least one PFAS detection.

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Most Americans receive their drinking water from publicly supplied sources, a large portion of it from groundwater. Mapping these populations consistently and at a high resolution is important for understanding where the resource is used and needs to be protected. The results show that 269 million people are supplied by public supply, 107 million are supplied by groundwater and 162 million are supplied by surface water.

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Preeclampsia (PE) is characterized by maternal hypertension, intrauterine growth restriction, and increased cytolytic natural killer cells (cNKs), which secrete interferon γ (IFNγ). However, the precise role of IFNγ in contributing to PE pathophysiology remains unclear. Using the reduced uterine perfusion pressure (RUPP) rat model of placental ischemia, we tested the hypothesis that neutralization of IFNγ in RUPPs will decrease placental reactive oxygen species (ROS) and improve vascular function resulting in decreased MAP and improved fetal growth.

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Phosphorus is a necessary nutrient for all organisms. However excessive phosphorus can cause eutrophication in surface water. Groundwater can be an important nonpoint contributor of phosphorus to surface water bodies.

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Data from 38,105 wells were used to characterize fluoride (F) occurrence in untreated United States (U.S.) groundwater.

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Domestic wells provide drinking water supply for approximately 40 million people in the United States. Knowing the location of these wells, and the populations they serve, is important for identifying heavily used aquifers, locations susceptible to contamination, and populations potentially impacted by poor-quality groundwater. The 1990 census was the last nationally consistent survey of a home's source of water, and has not been surveyed since.

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Chemical data from 43 334 wells were used to examine the role of land surface-soil-aquifer connections in producing elevated manganese concentrations (>300 μg/L) in United States (U.S.) groundwater.

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The U.S. Geological Survey (USGS) previously identified and mapped 62 Principal Aquifers (PAs) in the U.

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We estimate the location and population served by domestic wells in the contiguous United States in two ways: (1) the "Block Group Method" or BGM, uses data from the 1990 census, and (2) the "Road-Enhanced Method" or REM, refines the locations by using a buffer expansion and shrinkage technique along roadways to define areas where domestic wells exist. The fundamental assumption is that houses (and therefore domestic wells) are located near a named road. The results are presented as two nationally-consistent domestic-well population datasets.

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Data from 11,000 public supply wells in 87 study areas were used to assess the quality of nearly all of the groundwater used for public supply in California. Two metrics were developed for quantifying groundwater quality: area with high concentrations (km(2) or proportion) and equivalent-population relying upon groundwater with high concentrations (number of people or proportion). Concentrations are considered high if they are above a human-health benchmark.

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