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Biomedical subjects

D W Wilson

Publications and source records attributed to D W Wilson.

At least 19 recordsLinked to original sources
PubMed2006

Pulmonary arteriopathy and idiopathic pulmonary arterial hypertension in six dogs.

Pulmonary arteriopathy (PA) is the pathologic hallmark in human medicine of diffuse constrictive (medial and intimal remodeling) or multifocal complex (plexiform and dilatative lesions) arterial lesions, or both, that lead to irreversible obliteration of the arterial lumen. Clinically, PA leads to pulmonary arterial hypertension (PAH), of which idiopathic (IPAH) is one of the 5 subsets, and ultimately, to right-sided heart failure (RHF). Clinical and pathologic findings from 6 dogs with diagnosis of IPAH and PA were reviewed. These dogs were of various pure (5/6, 83%) and mixed (1/6, 17%) breeding, 5 months to 9 years (mean 5.2 years) old, and predominantly female (4/6, 67%) and reproductively intact (4/6, 67%). Doppler echocardiography (n = 5) indicated increased pulmonary arterial pressures during systole (70-135 mm Hg, mean 98 mm Hg) and diastole (35-80 mm Hg, mean 58 mm Hg). All 6 dogs had right ventricular pressure overload, right ventricular eccentric hypertrophy, and RHF. Histologic examination confirmed the clinical diagnosis of IPAH in all dogs, revealing PA characterized by 1 of the 4 main human histologic subsets: 1) isolated medial hypertrophy (1/6, 17%); 2) medial hypertrophy-intimal thickening without the plexiform lesion (1/6, 17%); 3) medial hypertrophy-intimal thickening concurrent with the plexiform lesion, which often was regionally clustered and situated near branching points of the respiratory artery, the poststenotic dilatation lesion, and vasculitis (4/6, 66%); and 4) isolated arteritis (1/6, 17%). Ancillary lesions similar to those in humans also complicated the PA (5/6, 83%). The complex lesions and ancillary exudative alveolitis seemed to be important indicators of severe, likely rapidly progressive and fatal, IPAH.

Animals↗
PubMed2005

The BMP type II receptor is located in lipid rafts, including caveolae, of pulmonary endothelium in vivo and in vitro.

Polymorphic mutations in the Bone Morphogenetic Protein type II receptor (BMPrII) gene have been implicated in the development of familial primary pulmonary hypertension (PPH) however, the role BMPrII mutations play in the development of PH has not yet been elucidated. Endothelial caveolae are an important domain of hemodynamics containing eNOS, the serotonin transporter, and endothelin receptors. In this study we show by standard immunohistochemistry (IHC) that BMPrII is widely distributed in the vasculature of the rat lung, and more specifically distributed to both apical and basal membranes of the arteriolar endothelium by fluorescent IHC. We also examined compartmentalization of BMPrII in lipid fractions of plasma membranes isolated by silica based extraction from human pulmonary artery endothelial cells and rat lung endothelium. Density gradient centrifugation demonstrated BMPrII in separate caveolin-1 (cav-1) and non-cav-1 lipid rich fractions. Electron microscopy co-localized cav-1 and BMPrII in flask shaped membrane fragments. Three-dimensional fluorescence microscopy demonstrated BMPrII in discrete membrane foci, a portion of which were co-localized with cav-1, as well as in Golgi. Our findings indicate that BMPrII is located within lipid-dense fractions of pulmonary endothelial cell membranes with a portion present in caveolae suggesting potential dynamic regulatory structural relationships.

Adult↗
PubMed2005

Interstitial lung disease in West Highland White Terriers.

Progressive respiratory failure and pulmonary fibrosis in West Highland White Terriers (WHWT) is an apparently genetic disorder of unknown pathogenesis. This study characterizes the light microscopic, ultrastructural, and immunohistochemical features of affected WHWT in comparison with lesions in usual interstitial pneumonia (UIP) of humans. Lesions in WHWT were confined to the expansion of the interstitial space of alveolar septa by extracellular matrix (ECM) determined to be mixtures of type-I and -III collagens. Features of UIP such as intra-alveolar fibroblastic foci, subpleural distribution, and honeycombing were not observed in six WHWT. Comparison with normal dogs showed no apparent increase in septal myofibroblasts. Ultrastructually, the ECM in alveolar septa consisted of large aggregates of periodic collagen filaments underlying alveolar capillaries that were surrounded by thick bands of amorphous to fine fibrillar matrix. This study suggests that chronic pulmonary disease of WHWT is a result of aberrant collagen regulation.

Animals↗
PubMed2003

The obligations of Member Countries of the OIE (World Organisation for Animal Health) in the Organisation of Veterinary Services.

The authors discuss the mission, organisation and resources of Veterinary Services in the new international trading environment and examine how the standards for Veterinary Services, contained in the OIE (World Organisation for Animal Health) International Animal Health Code (the Code), help provide the necessary support for Veterinary Services to meet their rights and obligations under the provisions of the Sanitary and Phytosanitary (SPS) Agreement of the World Trade Organization (WTO). The authors describe the challenges of gaining access to international trading markets through surveillance and control of OIE listed diseases. Finally, the approach in the Code to the principles underpinning the quality of Veterinary Services and to guidelines for evaluating Veterinary Services, is discussed.

Animal Welfare↗
PubMed2003

Approaches to resolving trade disputes.

The authors discuss the various approaches to resolving trade disputes available to Member Countries of the OIE (World organisation for animal health). The paper first describes the rights and obligations of Member Countries in setting health measures for the importation of animals and animal products, according to the provisions of the World Trade Organization (WTO) Agreement on the Application of Sanitary and Phytosanitary Measures (the SPS Agreement). The authors indicate how OIE standards may be used to set import measures and introduce issues such as equivalence and the use of provisional measures, which are both areas of potential conflict. The authors then describe the options available for resolving disputes--bilateral discussions, mediation through the OIE, the use of the WTO SPS Committee and the formal WTO dispute settlement process, discussing the advantages and disadvantages of each.

Animals↗
PubMed2001

Characterization of herpes simplex virus-containing organelles by subcellular fractionation: role for organelle acidification in assembly of infectious particles.

The cytoplasmic compartments occupied by exocytosing herpes simplex virus (HSV) are poorly defined. It is unclear which organelles contain the majority of trafficking virions and which are occupied by virions on a productive rather than defective assembly pathway. These problems are compounded by the fact that HSV-infected cells produce virus continuously over many hours. All stages in viral assembly and export therefore coexist, making it impossible to determine the sequence of events and their kinetics. To address these problems, we have established assays to monitor the presence of capsids and enveloped virions in cell extracts and prepared HSV-containing organelles from normally infected cells and from cells undergoing a single synchronized wave of viral egress. We find that, in both cases, HSV particles exit the nucleus and accumulate in organelles which cofractionate with the trans-Golgi network (TGN) and endosomes. In addition to carrying enveloped infectious virions in their lumen, HSV-bearing organelles also displayed nonenveloped capsids attached to their cytoplasmic surface. Neutralization of organellar pH by chloroquine or bafilomycin A resulted in the accumulation of noninfectious enveloped particles. We conclude that the organelles of the TGN/endocytic network play a key role in the assembly and trafficking of infectious HSV.

Brefeldin A↗
PubMed2001

Global trade requirements and compliance with World Trade Organization agreements: the role of tracing animals and animal products.

The use of a measure incorporating traceability that directly or indirectly affects international trade is permitted under the World Trade Organization Agreement on the Application of Sanitary and Phytosanitary Measures, provided that the measure is applied in accordance with the provisions of the Agreement. These provisions state that the measure must be necessary, scientifically justified, no more trade restrictive than required and consistent with the appropriate level of protection of the importing country. If requested, importing countries are required to assess claims by exporting countries regarding an alternative measure(s) providing an equivalent level of protection or with regard to regionalisation.

Animal Identification Systems↗
PubMed2000

Protein targets of monocrotaline pyrrole in pulmonary artery endothelial cells.

A single administration of monocrotaline to rats results in pathologic alterations in the lung and heart similar to human pulmonary hypertension. In order to produce these lesions, monocrotaline is oxidized to monocrotaline pyrrole in the liver followed by hematogenous transport to the lung where it injures pulmonary endothelium. In this study, we determined specific endothelial targets for (14)C-monocrotaline pyrrole using two-dimensional gel electrophoresis and autoradiographic detection of protein metabolite adducts. Selective labeling of specific proteins was observed. Labeled proteins were digested with trypsin, and the resulting peptides were analyzed using matrix-assisted laser desorption ionization mass spectrometry. The results were searched against sequence data bases to identify the adducted proteins. Five abundant adducted proteins were identified as galectin-1, protein-disulfide isomerase, probable protein-disulfide isomerase (ER60), beta- or gamma-cytoplasmic actin, and cytoskeletal tropomyosin (TM30-NM). With the exception of actin, the proteins identified in this study have never been identified as potential targets for pyrroles, and the majority of these proteins have either received no or minimal attention as targets for other electrophilic compounds. The known functions of these proteins are discussed in terms of their potential for explaining the pulmonary toxicity of monocrotaline.

Actins↗
PubMed2000

DNA damage cell checkpoint activities are altered in monocrotaline pyrrole-induced cell cycle arrest in human pulmonary artery endothelial cells.

Monocrotaline pyrrole (MCTP) causes cyto- and karyomegaly and persistent cell cycle arrest in the G2 stage of the cell cycle in cultured bovine pulmonary artery endothelial cells. To better characterize the cell cycle regulatory mechanisms of this process as well as determine whether this process would occur in cells of human origin, we treated human pulmonary artery endothelial cell (HPAEC) cultures with MCTP and determined, by flow cytometry, the expression of cyclin B1 and p53 in conjunction with DNA content. We also validated by Western blots that the persistence of cdc2 in its inactivated phosphorylated state, previously described in bovine cell cultures, occurred in HPAEC. Alterations in p53, cyclin A, cyclin B1, and cdc25c expression were also examined in Western blots of treated HPAEC extracts. The response of HPAEC to MCTP was compared with that of adriamycin and nocodazole, agents known to cause cell cycle alterations. Results of these experiments demonstrate that HPAEC treated with MCTP develop a population of cells in G2 that has increased cyclin B1 expression. These cells express increased amounts of cdc2 but not cdc25c. The ratio of inactive triphosphorylated cdc2 to the active monophosphorylated form increased moderately from control cultures in contrast to predominance of the active form in nocodazole-treated cultures. In addition, a second population of cells expressing cyclin B1 had continued incorporation of BrdU and DNA content consistent with 8 N chromosomes. A similar 8 N cell population was evident in nocodazole-treated cells but these cells had both cyclin B1 positive and negative components. Compared with adriamycin, a known inducer of p53, MCTP-treated HPAEC expressed p53 only at high concentrations and p53 expression was not coordinated with G2 arrest or polyploidy. We conclude that HPAEC treated with low concentrations of MCTP develop G2 arrest in association with persistent cyclin B1 expression, failure to completely activate cdc2, and continued DNA synthesis through a pathway that is unrelated to altered expression of p53.

Adult↗
PubMed2000

Synthesis and antitumour activity of new derivatives of flavone-8-acetic acid (FAA). Part 4: Variation of the basic structure.

A range of 11 derivatives of flavone-8-acetic acid (FAA) in which the structure has been substantially altered in different ways have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. The generally poor activity observed shows that the basic structure cannot be altered much without destroying the activity.

Animals↗
PubMed2000

Reconstruction of two- and three-dimensional images from synthetic-collimator data.

A novel SPECT collimation method, termed the synthetic collimator, is proposed. The synthetic collimator employs a multiple-pinhole aperture and a high-resolution detector. The problem of multiplexing, normally associated with multiple pinholes, is reduced by obtaining projections at a number of pinhole-detector distances. Projections with little multiplexing are collected at small pinhole-detector distances and high-resolution projections are collected at greater pinhole-detector distances. These projections are then reconstructed using the ML-EM algorithm. It is demonstrated through computer simulations that the synthetic collimator has superior resolution properties to a high-resolution parallel-beam (HRPB) collimator and a specially built ultra-high-resolution parallel-beam (UHRPB) collimator designed for our 0.38-mm pixel CdZnTe detectors. It is also shown that reconstructing images in three dimensions is superior to reconstructing them in two dimensions. The advantages of a high-resolution synthetic collimator over the parallel-hole collimators are apparently reduced in the presence of statistical noise. However, a high-sensitivity synthetic collimator was designed which again shows superior properties to the parallel-hole collimators. Finally, it is demonstrated that, for the cases studied, high-resolution detectors are necessary for the proper functionality of the synthetic collimator.

Algorithms↗
PubMed2000

ATP-Dependent localization of the herpes simplex virus capsid protein VP26 to sites of procapsid maturation.

The herpes simplex virus type 1 (HSV-1) capsid shell is composed of four major polypeptides, VP5, VP19c, VP23, and VP26. VP26, a 12-kDa polypeptide, is associated with the tips of the capsid hexons formed by VP5. Mature capsids form upon angularization of the shell of short-lived, fragile spherical precursors termed procapsids. The cold sensitivity and short-lived nature of the procapsid have made its isolation and biochemical analysis difficult, and it remains unclear whether procapsids contain bound VP26 or whether VP26 is recruited following shell angularization. By indirect immunocytochemical analysis of virally expressed VP26 and by direct visualization of a transiently expressed VP26-green fluorescent protein fusion, we show that VP26 fails to specifically localize to intranuclear procapsids accumulated following incubation of the temperature-sensitive HSV mutant tsProt.A under nonpermissive conditions. However, following a downshift to the permissive temperature, which allows procapsid maturation to proceed, VP26 was seen to concentrate at intranuclear sites which also contained epitopes specific to mature, angularized capsids. Like the formation of these epitopes, the association of VP26 with maturing capsids was blocked in a reversible fashion by the depletion of intracellular ATP. We conclude that unlike the other major capsid shell proteins, VP26 is recruited in an ATP-dependent fashion after procapsid maturation begins.

Adenosine Triphosphate↗
PubMed1999

Manipulation of injury and repair of the alveolar epithelium using two pneumotoxicants: 3-methylindole and monocrotaline.

The role of type II epithelial cell proliferation in repair of diffuse alveolar epithelial injury was examined using two pneumotoxicants, 3-methylindole (3-MI) and monocrotaline (MCT). It was hypothesized that if MCT inhibits type II epithelial cell mitosis, then pulmonary fibrosis would result after diffuse 3-MI-induced type I alveolar cell injury in rats preadministered MCT. Four groups of rats were given vehicle control, MCT, 3-MI, or MCT and 3-MI. Lungs from rats killed 4 days post-treatment were examined subjectively and quantitatively by light and electron microscopy. Proliferative stimulus was estimated by bromodeoxyuridine (BrdU) incorporation. Lungs from rats killed 2 weeks post-treatment were evaluated by light microscopy. At 4 days, the number of type II cells in the lungs of 3-MI-treated rats was 3 times greater than in the lungs of the dually (MCT/3-MI) treated rats which was the same as the control rat lungs. There was no significant difference between the MCT/3-MI-treated rats and the 3-MI-treated rats with regard to the percentage of denuded alveolar basement membrane. The number of BrdU-labeled type II epithelial cells was increased above the control in both 3-MI-treated groups, but was greater in the 3-MI-treated rat lungs than in the lungs of the MCT/3-MI-treated rats. The average type II cell volume in dually treated rats was 3 times the volume in the control animals and 50% greater than that in 3-MI-treated rats. Transmission electron microscopy of the lungs of the MCT/3-MI-treated rats demonstrated flattened hypertrophic type II cells over large portions of the basement membrane. The light microscopic appearance and collagen staining of the lungs of the dually treated rats were similar to the negative control rat lungs 2 weeks after dosing with 3-MI. This suggests that despite a proliferative stimulus, MCT inhibits type II cell division after diffuse alveolar type I cell injury, but that type II cell migration and coverage of the basal lamina proceed. Results of this study suggest that coverage of the denuded basal lamina by any method is sufficient to prevent interstitial alveolar fibrosis.

Animals↗
PubMed1999

ATP depletion blocks herpes simplex virus DNA packaging and capsid maturation.

During herpes simplex virus (HSV) assembly, immature procapsids must expel their internal scaffold proteins, transform their outer shell to form mature polyhedrons, and become packaged with the viral double-stranded (ds) DNA genome. A large number of virally encoded proteins are required for successful completion of these events, but their molecular roles are poorly understood. By analogy with the dsDNA bacteriophage we reasoned that HSV DNA packaging might be an ATP-requiring process and tested this hypothesis by adding an ATP depletion cocktail to cells accumulating unpackaged procapsids due to the presence of a temperature-sensitive lesion in the HSV maturational protease UL26. Following return to permissive temperature, HSV capsids were found to be unable to package DNA, suggesting that this process is indeed ATP dependent. Surprisingly, however, the display of epitopes indicative of capsid maturation was also inhibited. We conclude that either formation of these epitopes directly requires ATP or capsid maturation is normally arrested by a proofreading mechanism until DNA packaging has been successfully completed.

Adenosine Triphosphate↗
PubMed1998

Involvement of cytochrome P450 3A in the metabolism and covalent binding of 14C-monocrotaline in rat liver microsomes.

The metabolism and covalent binding of 14C-monocrotaline in Sprague-Dawley (SD) rat liver microsomes was investigated using the inducers dexamethasone, clotrimazole, pregnenolone-16 alpha-carbonitrile, and phenobarbital. Monocrotaline is a pyrrolizidine alkaloid (PA) that causes a syndrome in rats that is a model for human primary pulmonary hypertension. It has been documented that bioactivation of PAs (dehydrogenation to reactive pyrroles) in the liver by cytochromes P450 is required for their toxicity. Covalent binding of these reactive pyrroles to tissue macromolecules has been hypothesized to correspond to PA toxicosis. We correlated metabolism and total microsomal covalent binding of 14C-monocrotaline with cytochrome P450 3A using the aforementioned inducers, troleandomycin (a cytochrome P450 3A inhibitor), erythromycin N-demethylase assay of cytochrome P450 3A activity, and Western blots employing anti-rat cytochrome P450 3A antibodies. In addition, autoradiography of membranes electroblotted from SDS-PAGE demonstrated the formation of radiolabeled adducts with specific protein(s). The most intensely radiolabeled protein bands have an apparent molecular weight of approximately 52 kDa, which was similar to the molecular weight detected by anti-rat cytochrome P450 3A antibodies in the Western blots. No radiolabeled proteins were detected in microsomes pretreated with troleandomycin.

Animals↗
PubMed1998

Synthesis and antitumour activity of new derivatives of flavone-8-acetic acid (FAA). Part 3: 2-Heteroaryl derivatives.

A range of 14 derivatives of flavone-8-acetic acid (FAA) with a heterocyclic substituent in place of the 2-phenyl group have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. Some of the compounds, notably 2c,d and s, showed significant in vivo activity and these require further studies in order to evaluate their potential for development.

Animals↗