Biomedical subjects

James R Turk

Publications and source records attributed to James R Turk.

24 records · Page 2Linked to original sources

PubMed2003

Correlation of helical and incremental high-resolution thin-section computed tomographic imaging with histomorphometric quantitative evaluation of lungs in dogs.

OBJECTIVE: To develop protocols for helical computed tomography (CT) and axial high-resolution CT (HRCT) of lungs and correlate densitometric CT values with morphometric and histologic data for normal pulmonary tissue in dogs. ANIMALS: 8 healthy adult dogs. PROCEDURE: 2 dogs were used to establish a protocol for helical CT and HRCT of lungs. Six dogs were used to acquire densitometric CT data regarding normal lungs. After the dogs were euthanatized, their lungs were fixed and sampled for morphometric and histologic evaluation. Four CT acquisitions were compared by means of paired t tests. RESULTS: For normal lung tissue of dogs, mean densitometric CT value obtained during helical CT scans reconstructed in a sharp algorithm was -846 Hounsfield units. Values obtained via helical CT or HRCT acquisitions and reconstructed with sharp or standard algorithms did not differ significantly. Morphometric analysis was used to determine the proportion of lung parenchymal (82%) and non-parenchymal tissue (18%). Alveolar size, estimated by mean linear intercept, was approximately 172 microm, and alveolar surface area-to-volume ratio was 0.024 to 0.026 microm(-1). Histologic evaluation confirmed the presence of normal lung tissue. CONCLUSIONS AND CLINICAL RELEVANCE: Correlation of densitometric CT data with morphometric and histologic findings and the establishment of helical CT and HRCT protocols were attained; clinical use of this information may facilitate investigation of pulmonary disease in dogs. Sharp helical CT acquisitions were preferred because of better lung parenchyma detail and rapid image acquisitions, compared with HRCT.

Animals↗

PubMed2003

Maintaining patency and asepsis of vascular access ports in Yucatan miniature swine.

Subcutaneous vascular access ports allow for convenient serial blood sampling and the injection of pharmaceutical agents. However, their use can be complicated by infections leading to access-site cellulitis, bacteremia, and septic thrombophlebitis. Therefore, the implementation of techniques limiting infection is indicated to enhance the welfare of the animal and the collection of valid data. We hypothesized that as demonstrated in some human studies, adding vancomycin to the heparinized solution filling the port and catheter would reduce complications associated with vascular access ports. Adding 1 mg/ml vancomycin to the solution filling the port and catheter in Yucatan swine significantly reduced the rate of infections by 55% and doubled the duration of catheter patency. We also hypothesized that visualization of catheter placement and changing to a hydrocoated round-tipped polyurethane catheter would reduce the rate of complications. After appropriate changes in protocols were made, only one localized infection at a port site occurred in 10 pigs, and this infection was resolved with antibiotics. At necropsy, all ports and catheters were patent and free from the grossly apparent lesions typically associated with long-term vascular access ports. We conclude that the use of vancomycin in the port and catheter as well as optimizing the catheter type and placement reduce the complications typically observed with vascular access ports.

Animal Welfare↗

PubMed2002

Exercise training regulates SOD-1 and oxidative stress in porcine aortic endothelium.

Vascular oxidative stress contributes to endothelial dysfunction. Aerobic exercise training improves vascular function. The purpose of this study was to test the hypothesis that exercise training would improve the balance of antioxidant to prooxidant enzymes and reduce markers of oxidative stress in aortic endothelial cells (AEC). Female Yucatan miniature pigs either remained sedentary (SED) or were exercise trained (EX) for 16-19 wk. EX pigs had increased AEC SOD-1 protein levels and Cu/Zn SOD activity of the whole aorta compared with SED pigs. Protein levels of other antioxidant enzymes (SOD-2, catalase) were not affected by exercise training. Protein levels of p67(phox), a subunit of the prooxidant enzyme NAD(P)H oxidase, were reduced in EX vs. SED AEC. These EX adaptations were associated with lower AEC malondialdehyde levels and decreased phosphorylation of ERK-1/2. Endothelial nitric oxide synthase protein, protein nitrotyrosine content, and heme oxygenase-1 protein were not different in EX vs. SED pigs. We conclude that chronic aerobic exercise training influenced both antioxidant and prooxidant enzymes and decreased indexes of oxidative stress in AEC. These adaptations may contribute to improved endothelial function with exercise training.

Animals↗

PubMed2002

Immunohistochemical analysis of matrix metalloproteinase-1, -3, and -13 in naturally occurring cartilaginous tumors of dogs.

OBJECTIVE: To determine immunoreactivity of matrix metalloproteinase (MMP)-1, -3, and -13 in cartilaginous tumors of dogs, correlate expression of MMP with histologic grade of tumors and clinical outcome of dogs, and compare MMP immunoreactivity between chondrosarcomas and chondromas. SAMPLE POPULATION: Formalin-fixed, paraffin-embedded tissues obtained from samples of naturally occurring chondrosarcomas (n = 31) and chondromas (8) of dogs that were submitted to our veterinary medical diagnostic laboratory. PROCEDURE: Histologic sections from each sample were stained with H&E and monoclonal antibody to MMP-1, -3, and -13 by use of an avidin-peroxidase immunohistochemical technique. For each section, histologic grade (I, II, or III) and immunohistochemical expression (0, 1, 2, or 3) were evaluated. Clinical outcome was obtained from medical records or interviews with referring veterinarians and scored as a good outcome, moderate outcome, or poor outcome. Correlations among variables and differences between chondrosarcomas and chondromas were analyzed. RESULTS: Samples from chondrosarcomas had significantly higher immunoreactivity of MMP-1 and -13, compared with immunoreactivity in samples from chondromas. In chondrosarcomas, a significant positive correlation (r, 0.386) was found between MMP-1 and -13 immunoreactivities, and a significant negative correlation (r, -0.390) was detected between MMP-3 and -13 immunoreactivities. CONCLUSIONS AND CLINICAL RELEVANCE: A significant increase in expression of collagenases (MMP-1 and -13) in chondrosarcomas, compared with expression in chondromas, suggests that collagenases may play an important role in tumor progression, and possibly metastasis, in chondrosarcomas of dogs.

Animals↗

PubMed2002

Toxicity of fumonisin from Fusarium verticillioides culture material and moniliformin from Fusarium fujikuroi culture material when fed singly and in combination to growing barrows.

The effects of fumonisin B1 (FB1) from Fasarium verticillioides culture material and moniliformin from Fusarum fujikuroi culture material on growing barrows were evaluated. Four groups of six barrows (three replicates of two each; mean body weight, 11.1 kg) were fed diets containing 0 mg of FB1 and 0 mg of moniliformin per kg of feed (control), 100 mg of FB1 per kg of feed, 100 mg of moniliformin per kg of feed, and 100 mg of FB1 plus 100 mg of moniliformin per kg of feed. Barrows were fed these diets for 28 days. Body weight gain, feed efficiency, serum biochemical analytes, and hematological values were adversely affected by the FB1 and the FB1-plus-moniliformin diets. The moniliformin diet decreased body weight gain. Two barrows in the moniliformin diet group died, and two barrows in the FB1-plus-moniliformin diet group died. All deaths occurred during the first 6 days of the study. Mild to moderate lesions were observed microscopically in heart and lung tissues of the groups fed moniliformin and FB1 plus moniliformin and in liver tissues of the groups fed FB1 and FB1 plus moniliformin. Except for the acute mortality associated with the two diets containing moniliformin. clinical disease induced by the combined feeding of these two mycotoxins appears to be additive or less than additive and due primarily to the toxic expression of FB1.

Animal Feed↗

PubMedDate not supplied

Exercise training produces nonuniform increases in arteriolar density of rat soleus and gastrocnemius muscle.

OBJECTIVE: Exercise training has been shown to increase regional blood flow capacity to muscle tissue containing fibers that experience increased activity during exercise. The purpose of this study was to test the hypothesis that the increased blood flow capacity is partially the result of increases in arteriolar density (number of arterioles/mm2 of tissue), specifically in skeletal muscle tissue, with the largest relative increase in muscle fiber activity during training bouts. METHODS: This hypothesis was tested by comparing and contrasting the effects of endurance exercise training (ET) and interval sprint training (IST) on arteriolar density in soleus muscle (S) red (Gr) and white (Gw) portions of gastrocnemius muscle of male Sprague Dawley rats. ET rats completed 10 weeks of treadmill training 30 m/min, 15% grade, 60 min/day, 5 days/week, while IST rats completed 10 weeks of IST consisting of six 2.5-min exercise bouts, with 4.5-min rest between bouts (60 m/min, 15% incline), 5 days/week. The hypothesis would be supported if ET increased arteriolar density in S and Gr and if IST increased arteriolar density in Gw. RESULTS: ET increased arteriolar density above values of sedentary rats (SED) in both the Gw (ET = 0.93 +/- 0.19 arterioles/microm2; SED = 0.44 +/- 0.09 arterioles/microm2) and Gr (ET = 0.97 +/- 0.1 arterioles/microm2; SED = 0.51 +/- 0.06 arterioles/microm2) muscles, but not in S (ET = 1.69 +/- 0.45 arterioles/microm2; SED = 1.51 +/- 0.34 arterioles/microm2) muscle. In contrast, IST did not alter arteriolar density in Gw or Gr muscle tissue. Although arterial wall thickness was greater in S (3.95 +/- 0.40 microm) and Gr (6.24 +/- 0.59 microm) than Gw (2.76 +/- 0.18 microm), neither ET or IST altered mean wall thickness in either muscle. CONCLUSION: Increases in blood flow capacity produced in Gr and Gw by ET appear to be due in part to increased arteriolar density. In contrast, increased arteriolar density does not contribute to increased blood flow capacity of Gw in IST rats.

Adaptation, Physiological↗