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R Poston

Publications and source records attributed to R Poston.

At least 19 recordsLinked to original sources
PubMed2005

Enhanced vascular responses to adrenomedullin in mice overexpressing receptor-activity-modifying protein 2.

Adrenomedullin (AM) levels are elevated in cardiovascular disease, but little is known of the role of specific receptor components. AM acts via the calcitonin receptor-like receptor (CLR) interacting with a receptor-activity-modifying protein (RAMP). The AM1 receptor is composed of CLR and RAMP2, and the calcitonin gene-related peptide (CGRP) receptor of CLR and RAMP1, as determined by molecular and cell-based analysis. This study examines the relevance of RAMP2 in vivo. Transgenic (TG) mice that overexpress RAMP2 in smooth muscle were generated. The role of RAMP2 in the regulation of blood pressure and in vascular function was investigated. Basal blood pressure, acute angiotensin II-raised blood pressure, and cardiovascular properties were similar in wild-type (WT) and TG mice. However, the hypotensive effect of IV AM, unlike CGRP, was enhanced in TG mice (P<0.05), whereas a negative inotropic action was excluded by left-ventricular pressure-volume analysis. In aorta relaxation studies, TG vessels responded in a more sensitive manner to AM (EC50, 8.0+/-1.5 nmol/L) than WT (EC50, 17.9+/-3.6 nmol/L). These responses were attenuated by the AM receptor antagonist, AM(22-52), such that residual responses were identical in all mice. Remaining relaxations were further inhibited by CGRP receptor antagonists, although neither affected AM responses when given alone. Mesenteric and cutaneous resistance vessels were also more sensitive to AM in TG than WT mice. Thus RAMP2 plays a key role in the sensitivity and potency of AM-induced hypotensive responses via the AM1 receptor, providing evidence that this receptor is a selective target for novel therapeutic approaches.

Adrenomedullin↗
PubMed2005

The placental bed in pregnancies complicated by primary antiphospholipid syndrome.

UNLABELLED: Pregnancy in women with primary antiphospholipid syndrome (APS) is frequently associated with placental insufficiency leading to intrauterine growth restriction (IUGR)+/-fetal death, pre-eclampsia, placental abruption, premature delivery or thrombosis. The aim of this study was to investigate the placental bed in APS pregnancies for evidence of impaired trophoblast invasion, endothelial cell activation (ECA) and macrophage infiltration. METHODS: Biopsies from the presumed site of the placental bed were obtained from 12 women with treated primary APS and 16 controls. Immunohistochemical methods were employed to investigate expression of cytokeratin (trophoblasts), alpha-actin (smooth muscle), CD68 (macrophages) and VCAM-1 (as marker of ECA). Fibrinoid and elastin distribution and expression were determined by periodic acid/Schiff and orcein stain, respectively. RESULTS: Three APS pregnancies developed IUGR, one with concurrent pre-eclampsia. Eight of 12 APS biopsies were confirmed to be from the placental bed; one patient failed to meet APS criteria and was excluded from analysis; six included spiral arteries in the biopsy; 11 of 16 controls' biopsies were from the placental bed. APS biopsies had a higher concentration of inflammatory cells (p=0.0001), particularly macrophages (p=0.014). Three APS biopsies showed necrosis with hyperplastic vessels; one demonstrated arterial thromboses, but none had profound vasculopathy/atherosis or ECA. CONCLUSION: Inflammatory mechanisms in the placental bed may contribute to APS pregnancy complications.

Antiphospholipid Syndrome↗
PubMed2001

An objective method for grading ultrasound images of carotid artery plaques.

Plaque composition may improve identification of patients at risk of stroke. A new method of grading ultrasound (US) images to assess plaque composition is described. B-mode US images were obtained from 50 carotid specimens. Image analysis parameters were entered into a discriminant analysis package and compared retrospectively with histology. Discriminant functions were derived and then applied prospectively to image-analysis data obtained from a further 50 plaque specimens. For the prospective analysis, US images were graded according to the relative contribution of calcium, fibrous tissue, haemorrhage and lipid. The accuracy for retrospective classification of calcium was 100%, for fibrous tissue 97%, for lipid 76% and 68% for haemorrhage (kappa = 0.81). Prospective classification showed an overall agreement of 65% (kappa = 0.47). Significant intraplaque haemorrhage was identified with an 81% sensitivity and 83% specificity. The US method described demonstrated improved accuracy compared to previous studies. Further study is required to establish the use of this method for in vivo images and its correlation with patient symptoms.

Aged↗
PubMed2001

Increased ICAM-1 and PECAM-1 transcription levels in the heart of Apo-E deficient mice in comparison to wild type (C57BL6).

Adhesion molecules and chemoattractants are thought to play a critical role in the homing of leukocytes to sites of vascular lesions. Apo-E deficiency in mice creates an atherosclerotic model that mimics vascular lesions in man. Little is known on the effect of Apo-E deficiency on expression of adhesion molecules in the hearts of these animals. In this study, male C57BL6 and Apo-E deficient mice were fed a chow diet over periods of time (0 to 20 weeks). The transcription levels of major adhesion molecules (ICAM-1, PECAM-1), present in the heart, were followed by northern blots. Immunohistochemistry was used to localize these adhesion molecules in the heart. Results show a significant increase in gene transcription levels of ICAM-1 and PECAM-1 in Apo-E animals, but not wild type, at 16 and 20 weeks of chow diet. Such increase in levels of transcription was not observed in younger Apo-E and C57BL6 animals (0, 6 weeks of diet). ICAM-1 and PECAM-1 were strongly expressed in the endocardium and heart microvessels. In contrast, VCAM-1 was poorly stained, with only an occasional expression on the endocardium and arterioles. Enhanced gene expression levels of heart ICAM-1 and PECAM-1 observed in Apo-E deficient mice, but not in control animals, appears to induce the initial stages of an inflammatory reaction. Such observations, not previously reported, may induce heart vascular remodeling.

Animals↗
PubMed2000

Modulation of expression of endothelial intercellular adhesion molecule-1, platelet-endothelial cell adhesion molecule-1, and vascular cell adhesion molecule-1 in aortic arch lesions of apolipoprotein E-deficient compared with wild-type mice.

Human vascular adhesion molecules, such as intercellular adhesion molecule-1 (ICAM-1), platelet-endothelial cell adhesion molecule-1 (PECAM-1), and vascular cell adhesion molecule-1 (VCAM-1), are thought to play a critical role in the homing of leukocytes to sites of atherosclerotic lesions. However, very little is known about the expression of adhesion molecules in the vasculature of mice models, such as apolipoprotein E knockout (apoE(-/-)) mice, the lesions of which closely mimic human atherosclerotic lesions. This study has first quantitatively characterized the mean expression of endothelial adhesion molecules, lining the whole vessel intimal circumference, over a period of time (0 to 20 weeks of diet) in aortic arch lesions of male apoE-deficient compared with wild-type (C57BL/6) mice. These animals were fed a chow or a cholesterol-rich diet. ApoE(-/-) animals showed first an increase (at 6 weeks) and then a reduction (at 16 weeks) in the mean expression of ICAM-1 (P<0.05) and PECAM-1 (P<0.05) but not VCAM-1 levels. Such modulation of the mean expression of adhesion molecules was not observed in wild-type mice. Confirmation of immunohistochemistry results on ICAM-1 was obtained by Northern blots performed on the aortic arch of apoE and C57BL6 chow-fed mice over a period of 20 weeks. Moreover, the presence of VCAM-1 was also confirmed at the RNA level, on aortas of control and apoE mice, by reverse transcription-polymerase chain reaction. In the second part of the study, we assayed the levels of adhesion molecules, in different types of histologically defined atherosclerotic lesions, in apoE(-/-) animals fed for 20 weeks. All 3 adhesion molecules (ICAM-1, PECAM-1, and VCAM-1) were observed to be reduced in fibrofatty and complex lesions but not in fatty streaks or in areas without lesions. These results indicate that the expression of these adhesion molecules in apoE-deficient animals varies with the evolution of the plaque from a fatty to a fibrous stage.

Animal Feed↗
PubMed1999

Expression of nitric oxide synthase isoforms in pregnant human myometrium.

1. Endogenous nitric oxide has been proposed to play a role in the control of myometrial contractility in pregnancy. In this study, the expression, localisation and regulation of nitric oxide synthase (NOS) isoforms have been examined in human pregnant myometrium and cultured human myometrial smooth muscle cells, by immunoblotting, immunohistochemistry and reverse transcription-polymerase chain reaction. 2. Immunoblotting of extracts from freshly isolated myometrial tissue, affinity-enriched for NOS proteins by precipitation with ADP-sepharose, revealed expression of endothelial NOS (eNOS or NOS3) in tissues from preterm, term non-labour and active labour at term. Inducible NOS (iNOS or NOS2) and neuronal NOS (nNOS or NOS1) proteins were not detected at any stage of pregnancy. 3. Immunohistochemical detection showed that expression of eNOS protein was restricted to the endothelium of the myometrial vasculature, with no staining detected in myometrial smooth muscle cells. 4. Messenger RNA for all three NOS isoforms was detected, although iNOS and nNOS mRNAs were detectable only with high cycle number, implying a low copy number. 5. NOS isoforms were not detectable in human myometrial smooth muscle cells cultured from term non-labour pregnancies. Cytokine stimulation of cultured myometrial cells did not induce iNOS expression or nitrite accumulation in the culture medium, although both iNOS protein and nitrite release were detected in the human pulmonary epithelial cell line A549. 6. Levels of eNOS protein and of NOS mRNA expression were not correlated with gestational stage, suggesting that endogenously produced NO is not likely to be a modulator of myometrial tone during human pregnancy.

Adult↗
PubMed1999

Normal expression of tissue factor, thrombomodulin, and annexin V in placentas from women with antiphospholipid syndrome.

OBJECTIVE: Placentas from pregnancies complicated by antiphospholipid syndrome often show thromboses and infarction, which may result from aberrations in placental coagulant pathways. We tested the hypothesis that alterations in tissue factor, thrombomodulin, and annexin V expressions contribute to poor pregnancy outcome associated with antiphospholipid syndrome. STUDY DESIGN: Frozen sections from random biopsy samples of the basal plates of placentas from patients with primary antiphospholipid syndrome (n = 9), patients with secondary antiphospholipid syndrome (n = 3), and gestational age-matched control subjects (n = 10) were immunostained for tissue factor, thrombomodulin, and annexin V. Intensity of immunostaining was assessed by means of quantitative image analysis. Annexin V protein expression was evaluated with Western blotting techniques. RESULTS: Tissue factor was expressed in the perivascular cells of the villous vasculature. Thrombomodulin and annexin V immunostaining was localized to the syncytiotrophoblast. There were no differences in the intensity of immunostaining for tissue factor, thrombomodulin, and annexin V between placentas from women with antiphospholipid syndrome and those from control subjects. Western blot analysis of annexin V expression showed no differences between study patients and control subjects. CONCLUSION: Alterations in placental coagulant pathways involving tissue factor, thrombomodulin, and annexin V do not contribute to poor pregnancy outcome associated with antiphospholipid syndrome.

Adult↗
PubMed1999

Monocyte chemotactic protein-1 (MCP-1) accelerates the organization and resolution of venous thrombi.

PURPOSE: Organization, recanalization, and contraction are common to wound healing and thrombus resolution. Monocytes are essential to wound healing and are also found in venous thrombi. We measured endogenous levels of the monocyte chemotactic protein-1 (MCP-1) in naturally resolving venous thrombi and determined the effect of injecting MCP-1 into newly formed thrombus. METHODS: Endogenous MCP-1 levels were estimated in rat blood, thrombi, and the adjacent vessel wall after thrombus formation, in cohorts of eight animals at 1, 7, and 14 days. In another group (n = 10), 1 microgram of MCP-1 was injected into newly formed thrombi. Carrier was injected into the thrombi of control animals (n = 10). Thrombi and adjacent vein walls were obtained for histology at 7 days. Thrombi were given an arbitrary organization score based on erythrocyte and extracellular matrix content, which was assessed by means of computerized and observer analysis. Specimen weight, thrombus area, and cellular and monocyte content were measured. RESULTS: Endogenous MCP-1 increased between days 1 and 7 in the thrombus (1-day median, 1.1 ng/g wet wt; 1-day range, 0.8 to 1.4 ng/g wet wt; 7-day median, 5.4 ng/g wet wt; 7-day range, 1.5 to 7.4 ng/g wet wt; P <.0001) and vein wall (1-day median, 1.5 ng/g wet wt; 1-day range, 0.8 to 4.3 ng/g wet wt; 7-day median, 3.3 ng/g wet wt; 7-day range, 2.7 to 8.3 ng/g wet wt; P <. 05). At 14 days, thrombus was incorporated in the vein wall, and total MCP-1 levels remained high (median, 3.9 ng/g wet wt; range, 1.1 to 7.4 ng/g wet wt). Less MCP-1 was found in the thrombus than the adjacent vessel wall at day 1 (P <.05), but there was no difference at day 7. MCP-1 could not be detected in the blood. MCP-1 injection into thrombus increased the computer (P =.016) and observer (P =.004) organization scores, reduced the thrombus area (from median, 3. 4 mm(2), and range, 1.5 to 5.7 mm(2), to median, 0.2 mm(2), and range, 0.02 to 2.6 mm(2); P =.048), and increased the surrounding vessel wall monocyte content (P =.008). Specimen weights of treated animals were lower than those of control animals (P <.02). CONCLUSION: Venous thrombus MCP-1 levels increase during natural resolution. MCP-1 treatment increased the organization and resolution of thrombi. MCP-1 may therefore be of therapeutic use.

Animals↗
PubMed1999

In ovo vaccination technology.

More than 80% of the U.S. broiler industry has converted to the in ovo vaccination process for control of Marek's disease. Providing certain criteria are met, including timing and site of vaccine placement, vaccine mixing, machine sanitization, and hatchery management specifications, this has proven to be an efficacious and convenient method of vaccination. Efforts to extend the technology for other viral vaccines including Newcastle, bronchitis and bursal disease, and bacterial and parasitic vaccines are in progress. Collectively, these studies demonstrate that in ovo vaccination technology using approved vaccine is a safe, efficacious, and convenient method for vaccination of poultry.

Animals↗
PubMed1997

Localization of endothelial proliferation and microvascular expansion in active plaque psoriasis.

Expansion of the dermal microvasculature is a prominent feature of psoriasis. Although the pathogenetic process resulting in vascular morphological changes remains unclear, considerable evidence suggests the involvement of angiogenesis. To assess the degree and site of psoriatic microvascular expansion, immunohistochemical studies were performed on paired lesional and non-lesional specimens from 10 patients with active, untreated plaque psoriasis. Five-micron thick sections were labelled with monoclonal antibody JC/70A specific for the endothelial marker CD31, and vascular quantification was achieved using hue-saturation-intensity image analysis. Assessment of vasculature in the papillary dermis (superficial plexus) demonstrated a fourfold increase in endothelial surface area of lesional compared with non-lesional skin (P < 0.01), while there was no significant increase in vasculature of the upper reticular dermis. Subsequently, 18-micron thick sections were double-labelled with MIB-1 antibody to the nuclear proliferation marker Ki-67 and JC/70A. Endothelial cell proliferation was identified in the vertical limbs of capillary loops in eight out of 10 lesional biopsies and in no non-lesional biopsies. The endothelial MIB-1 labelling index was 3.1% of total endothelial cells of the superficial plexus. These findings confirm endothelial proliferation underlying psoriatic microvascular expansion, and indicate that this process is limited to a specific site in the dermal capillary bed.

Adult↗
PubMed1995

Altered vascular endothelium integrin expression in psoriasis.

Considerable evidence indicates that microvascular changes observed in psoriasis are a result of vascular proliferation. A critical step in the sequence of events leading to neovascularization involves interactions between endothelial cells and extracellular matrix proteins mediated in part by the integrin family of adhesion molecules. A number of endothelial integrins have been shown to participate in neovascularization, including members of the beta 1, beta 3, and beta 4 subfamilies. To investigate the role of these integrins in psoriasis, specimens of lesional and nonlesional skin were taken from 10 patients with active, untreated plaque disease. Vascular endothelium was labeled with monoclonal antibodies specific for alpha 2, alpha 5, alpha 6, beta 1, av beta 3, and beta 4 integrins. The use of image analysis permitted quantification of immunoperoxidase staining and comparison of endothelial labeling in lesional and nonlesional skin. There was a significant increase in endothelial staining of av beta 3 integrin in lesional compared with nonlesional skin, both in superficial and deep vasculature. In contrast, there was a significant decrease in endothelial beta 4 staining in lesional compared with nonlesional superficial dermal vessels, alpha 2, alpha 5, alpha 6, and beta 1 staining showed no significant difference between the two groups. These results demonstrate an important role of av beta 3 and beta 4 integrins in the microvascular changes of psoriatic lesions.

Adult↗
PubMed1993

Cytokine expression in synovial membranes of patients with rheumatoid arthritis and osteoarthritis.

OBJECTIVES: To compare, by immunohistochemistry, the cellular and cytokine profile in rheumatoid arthritis (RA) and osteoarthritis (OA) synovial membranes (SMs). Synovium was obtained at knee arthroplasty from 10 patients with RA and 10 with OA. METHODS: Synovial membranes were stained with a panel of monoclonal antibodies (MAb) to assess cytokine expression (IL-1 alpha, IL-1 beta, IL-6, GM-CSF, TNF-alpha and EGF) and the intensity of the mononuclear cellular infiltrate (MNC). RESULTS: Significantly greater percentages of IL-1 alpha, IL-1 beta, IL-6, TNF-alpha, GM-CSF and EGF cells were detected in all areas of the rheumatoid SMs when compared with osteoarthritic SMs. Five RA but only one OA SM demonstrated focal lymphoid aggregates. Lining layer thickening was noted in RA SMs only. The intensity of the MNC and number of blood vessels were greater in the RA group. CONCLUSION: The results suggest that the differences in cytokine production by RA and OA SMs are quantitative but that the greater thickness of the synovial lining layer and higher vascularity may be specific to RA.

Adult↗
PubMed1992

Paradoxical emboli in elderly patients.

We report two elderly patients who each had a patent foramen ovale (PFO) and were considered to have had paradoxical emboli. In one patient the PFO was detected by contrast two-dimensional echocardiography, whereas in the other it was demonstrated at post-mortem examination. This is an unusual but treatable condition, particularly difficult to diagnose in older people and probably occurring more frequently than is generally suspected.

Aged↗
PubMed1991

Inflammatory processes in asthma.

Bronchial inflammation is a characteristic of asthma, but, although postmortem and rare bronchoscopic studies had been performed, it is only after 1980 that many experiments were done. Electron microscopy, immunohistochemistry and molecular biology have enhanced our knowledge. As bronchial biopsies and bronchoalveolar lavage present drawbacks, it is favorable to combine both to obtain the best insights into inflammation. The epithelium is rarely intact in asthmatic patients, the cells being both 'fragile' and activated. Eosinophil inflammation is highly important and likely involved in the damage of the epithelium and submucosa. Airway macrophages and monocytes are present in greater amounts and are activated in the bronchi, and they are certainly involved in the pathogenesis of asthma. Mast cells are activated and some emphasis has been put on lymphocytes. Therefore, asthma appears to be a desquamative bronchitis with mixed cell infiltrate.

Acute Disease↗
PubMed1990

Use of anti-CD3 monoclonal antibody in the generation of effector cells from human solid tumors for use in cancer biotherapy.

Activated lymphocytes derived from tumor biopsies are very important as a source of biotherapy for cancer. The growth of lymphocytes requires periodic stimulation with specific antigen. In the case of tumor-derived lymphocytes, tumor cells in the biopsy can serve this function. This stimulation provides proliferative potential as well as functional specificity. Often, however, required numbers of viable tumor cells are not available for antigen dosing. In the present study, anti-CD3 antibody was used as a substitute for specific antigen in the generation of effector cells for biotherapy. Periodic stimulation of tumor-derived activated cells (TDAC) using anti-CD3 antibody immobilized on plastic tissue culture plates or PL-732 plastic bags resulted in continued proliferation of the TDAC. In addition, maintenance of cytotoxic activity was observed. In this study, we expanded lymphocytes from 15 tumor biopsies (five different tumor types) to therapeutic doses (greater than 5.0 X 10(10) TDAC). The average time for expansion was 70 days. Our studies showed upregulation of CD25 expression by 18 h. Proliferation of the TDAC occurred when cultures were supplemented with interleukin-2 (IL-2). The characteristics of anti-CD3 antibody-stimulated TDAC were similar to those reported before by our group using tumor biopsy for stimulation. This study provides evidence for the practical usefulness of anti-CD3 antibody stimulation of lymphocytes used in the biotherapy of cancer.

Antibodies, Monoclonal↗