Publications by authors named "John W Walker"

Little is known about the effects of woody plant encroachment-a recent but pervasive phenomenon-on the hydraulic properties of bedrock substrates. Recent work using stream solute concentrations paired with weathering models suggests that woody plant encroachment accelerates limestone weathering. In this field study, we evaluate this hypothesis by examining bedrock in the Edwards Plateau, an extensive karst landscape in Central Texas.

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A sodium pentobarbital-induced sleep time study was conducted on 15 adult intact male Boer × Spanish goats selected for high (J+, n = 7) or low (J-, n = 8) juniper consumption (estimated breeding values of 13.1 ± 1.0 and -14.

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Encroaching plant species in West Texas continues to significantly reduce livestock production capacity and cause an imbalance between plant and livestock ecology. and are encroaching species rarely used by browsing animals, mainly due to phytochemical defenses. spp.

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The microbial population in the gastrointestinal tract of ruminant animals aids in the utilization of forages with high levels of secondary plant compounds. Two divergent bloodlines of meat goats have been selected by screening fecal samples with near-infrared reflectance spectroscopy to assess the goat's consumption of high or low levels of sp. leaves containing several monoterpenes, including camphor.

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Diet selection and preference by grazing animals are determined by genetic and environmental factors (i.e., nature and nurture) that interact and affect their efficacy for managing vegetation as targeted grazers.

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Background: We have previously reported that the upregulation of galectin-9 (Gal-9) on CD4 and CD8 T cells in HIV patients was associated with impaired T cell effector functions. Gal-9 is a ligand for T cell immunoglobulin and mucin domain-3, and its expression on T cells in cancer has not been investigated. Therefore, we aimed to investigate the expression level and effects of Gal-9 on T cell functions in patients with virus-associated solid tumors (VASTs).

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Background: Avelumab, a human anti-programmed death-ligand 1 immunoglobulin G1 monoclonal antibody, showed favorable efficacy and safety in patients with metastatic Merkel cell carcinoma (mMCC) in the phase II JAVELIN Merkel 200 trial, leading to approval in multiple countries. We describe real-world experience with avelumab in patients with mMCC from an expanded access program.

Methods: Eligible patients had mMCC and progressive disease during or after chemotherapy or were ineligible for chemotherapy or clinical trial participation.

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Background: Authorship is an important yardstick in academic medicine. The purpose of this study was to assess the prevalence of authorship conflicts among academic plastic surgeons and determine any change in authorship awareness over an 8-year period.

Methods: In 2003, members of the American Association of Plastic Surgeons were surveyed using an anonymous, 15-item, one-page questionnaire.

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We investigated whether Mediterranean goats use salivary tannin-binding proteins to cope with tannin-rich forages by determining the affinity of salivary or parotid gland proteins for tannic acid or quebracho tannin. Mixed saliva, sampled from the oral cavity, or parotid gland contents were compared to the intermediate affinity protein bovine serum albumin with a competitive binding assay. Goats that consume tannin-rich browse (Damascus) and goats that tend to avoid tannins (Mamber) were sequentially fed high (Pistacia lentiscus L.

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Objective: To identify a strain of contagious ecthyma virus from goats that possesses the appropriate characteristics for an effective vaccine for goats.

Animals: 25 goat kids used for vaccine development and 100 goat kids used for evaluation of vaccine efficacy.

Procedures: 5 strains of contagious ecthyma virus were tested in a vaccination-challenge study to identify the best strain to be the seed strain for a contagious ecthyma vaccine.

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Background: In the IL-10 gene-deficient mouse model, development of intestinal inflammation is associated with a defect in epithelial barrier integrity that is thought to allow sufficient passage of bacteria or bacterial antigens to initiate a mucosal immune response. Microbial monoassociation experiments into axenic animals have shown that some, but not all, endogenous bacteria will initiate an intestinal inflammatory response. For instance, Bacteroides vulgatus does not initiate intestinal inflammation in axenic IL-10 gene-deficient mice.

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Intestinal flora plays a critical role in the initiation and perpetuation of inflammatory bowel disease. This study examined whether live fecal bacteria were necessary for the initiation of this inflammatory response or whether sterile fecal material would provoke a similar response. Three preparations of fecal material were prepared: (1) a slurry of live fecal bacteria, (2) a sterile lysate of bacterial antigens, and (3) a sterile filtrate of fecal water.

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Probiotics have been shown to reduce the incidence of colon cancer in animal models. The mechanisms responsible for this activity are poorly defined. Conjugated linoleic acids (CLA) are a group of isomers of linoleic acid (LA) possessing anti-inflammatory and anticarcinogenic properties, which can be produced from LA by certain bacterial strains.

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AMPK acts as a cellular fuel gauge and responds to decreased cellular energy status by inhibiting ATP-consuming pathways and increasing ATP-synthesis. The aim of this study was to examine the role of AMPK in modulating poly(ADP-ribose) polymerase (PARP), a nuclear enzyme involved in maintaining chromatin structure and DNA repair. HT-29 cells infected with constitutively active AMPK demonstrated increased PARP automodification and an increase in bioNAD incorporation.

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Serum amyloid A (SAA) is an acute-phase protein whose levels positively correlate with disease activity in inflammatory bowel diseases. In this study we investigated the impact of SAA on NF-kappaB signaling and proinflammatory gene expression in intestinal epithelial cells (IEC). Human HT-29 and Caco-2 monolayers were stimulated with recombinant SAA and NF-kappaB activation/NF-kappaB-dependent gene expression measured.

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We report the first maternal pulmonary adenocarcinoma metastatic to the fetus as well as an updated literature review. Review of the literature revealed that there have been only 67 cases of maternal malignancy metastatic to the products of conception. These were mostly malignant melanoma and hematopoietic tumors.

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Juvenile hemangiomas are the most common tumors of infancy, occurring in as many as 10% of all births. These benign vascular lesions enlarge rapidly during the first year of life by hyperplasia of endothelial cells and attendant pericytes and then spontaneously involute over a period of years, leaving loose fibrofatty tissue. Several hypotheses have been put forth concerning hemangiogenesis, including the possibility that the tumor is the result of somatic mutation in one or more components of critical vascular growth-regulatory pathways.

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