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Ventzislav Petkov

Publications and source records attributed to Ventzislav Petkov.

9 recordsLinked to original sources
PubMed2006

Involvement of endothelial NO in the dilator effect of VIP on rat isolated pulmonary artery.

The endothelium and its interaction with smooth muscle play a central role in the local control of the pulmonary vasculature, and endothelial dysfunction is thought to contribute to pulmonary hypertension and chronic obstructive pulmonary disease. Vasoactive intestinal peptide (VIP), a 28-amino acid neuropeptide, relaxes the rat pulmonary artery, but there is controversy as to whether or not this action of VIP depends on the endothelium. The aim of this study, therefore, was to investigate the role of the endothelium and nitric oxide (NO), the major endothelium-derived relaxing factor, in the dilator action of VIP on the rat isolated pulmonary artery. Pulmonary artery preparations pre-contracted by the alpha(1)-adrenoceptor agonist L-phenylephrine were relaxed by VIP (0.003-1 microM) and acetylcholine (0.003-10 microM) in a concentration-dependent manner. Mechanical removal of the endothelium reduced the maximal response to VIP by about 50% and practically abolished the response to acetylcholine. Inhibition of NO synthesis by N(omega)-nitro-L-arginine methyl ester (0.5 mM) had a similar effect, abolishing the vasorelaxation caused by acetylcholine and attenuating the vasorelaxation caused by VIP by about 50%. From these data it is concluded that the relaxant action of VIP on the rat isolated pulmonary artery depends in part on the presence of the endothelium and that this part is mediated by endothelial NO.

Acetylcholine↗
PubMed2006

Vasoactive intestinal peptide gene alterations in patients with idiopathic pulmonary arterial hypertension.

Pulmonary arterial hypertension is a progressive disease, characterised by increased proliferation of pulmonary artery smooth muscle cells, vasoconstriction and remodelling of the vascular wall leading to right heart failure and death. The idiopathic form is rare (idiopathic arterial primary hypertension (IPAH); formerly PPH, MIM# 178600). Our group correlated a deficiency in vasoactive intestinal peptide (VIP; MIM# 192320) levels in serum and lung tissue with the pathogenesis of IPAH. The aim of this study was to investigate the relevance of genetic alterations in VIP to the development of IPAH. We screened 10 patients (age 4-66 years) for alterations in the coding, the noncoding regions and the enhancer region of the VIP gene by direct sequencing. In eight of 10 patients, we found alterations compared to the wild-type sequence. We detected nine alterations. In the noncoding regions, eight alterations were in the introns 1, 2, 3 and 4 (g.448G>A g.501C>T g.764T>C g.2267A>T g.2390C>T g.3144T>C g.3912A>G g.4857A>G). In the coding regions, a single alteration in the 3' untranslated region in exon 7 (g.8129T>C) was observed in five patients. It appeared in 46% of the control group. The frequency of this alteration in the coding region of the VIP gene could therefore not be correlated with the appearance of IPAH. Apart from the importance of VIP signalling, genetic and/or environmental modifiers might therefore contribute to the development and perpetuation of the disease.

3' Untranslated Regions↗
PubMed2006

Antibiotic treatment is not effective in patients infected with Helicobacter pylori suffering from extragastric MALT lymphoma.

PURPOSE: Apart from anecdotal reports implicating Helicobacter pylori (HP) in the development of extragastric mucosa associated lymphoid tissue (MALT) lymphoma, no large scale prospective studies have been performed on this topic. PATIENTS AND METHODS: A total of 77 patients with extragastric MALT lymphoma were prospectively studied. The presence or absence of HP was tested by histology, urease breath test, and serology. Patients were also tested for hepatitis A, B, and C and autoimmune conditions along with assessment of MALT lymphoma-specific genetic changes. RESULTS: Evidence for infection with HP was present in 35 of 77 patients (45%), and three of 75 patients tested (4%) were positive for hepatitis C and one for hepatitis B. All patients with HP-infection underwent eradication, 16 before initiation of further therapy. Apart from one patient with lymphoma involving parotid and colon, who achieved regression of the colonic lesions, none of these 16 patients showed regression of the lymphoma after a median follow-up of 14 months (range, 8 to 48+ months) before initiation of definitive treatment. No correlation between HP-status, localization, stage, autoimmune diseases, and genetic findings was seen. CONCLUSION: In our series, HP-eradication was ineffective for treatment of extragastric MALT lymphomas. This finding, along with an infection rate of 45%-as could also be expected in the general Austrian population-suggests that HP does not play a role in the development of these lymphomas. Antibiotic treatment targeting HP should, therefore, be discouraged in patients with extragastric MALT lymphomas.

Adult↗
PubMed2006

The vasoactive intestinal peptide receptor turnover in pulmonary arteries indicates an important role for VIP in the rat lung circulation.

Vasoactive intestinal peptide (VIP) is a potent vasorelaxing peptide that plays a role in lung physiology and possibly in pulmonary hypertension. We investigated the turnover of the VIP receptors on rat pulmonary arteries ex vivo. There was evidence for a fast receptor turnover in pulmonary arteries, which underlines the important role of VIP for the regulation of pulmonary circulation and pulmonary pathology.

Acetylcholine↗
PubMed2004

The influence of VIP and epoprostenol on platelet CD62P expression and primary haemostasis in vitro.

Human vasoactive intestinal peptide (VIP) and epoprostenol (prostacyclin) have vasodilatative effects in the pulmonary circulation. Both VIP and epoprostenol are successfully used to treat pulmonary hypertension in humans and experimental animal models. The positive effects of epoprostenol on the course of this disease are achieved through vasodilatation and inhibitory effects on platelet activity. Since VIP also binds specifically to platelets, we compared the in vitro effects of VIP and epoprostenol on platelet P-Selectin (CD62P) expression and primary haemostasis. Anti-aggregative effects of VIP (10(-6) mol and 10(-8) mol) and epoprostenol (50, 5 and 0.5 ng/ml) on platelets were determined by agonist-induced CD62P expression and in vitro bleeding time (PFA-100 trade mark system). Blood from healthy individuals was either incubated with epoprostenol, VIP or saline control and was analysed by whole blood flow cytometry and the PFA-100 trade mark. Prior to flow cytometric analysis, the platelets were stimulated with either arachidonic acid (AA) or adenosine diphosphate (ADP). Whole blood flow cytometry analysis showed that epoprostenol inhibited dose-dependently agonist-induced CD62P expression, whereas VIP did not inhibit CD62P expression. PFA analysis revealed substantial closure time prolongation by epoprostenol and again no effects of VIP. These results indicate that VIP, in contrast to epoprostenol, has no effect on platelet CD62P expression and primary haemostasis.

Adenosine Diphosphate↗
PubMed2004

The calcium channel blocker amlodipine exerts its anti-proliferative action via p21(Waf1/Cip1) gene activation.

Proliferation of vascular smooth muscle cells (VSMC) contributes to the progression of atherosclerotic plaques. Calcium channel blockers have been shown to reduce VSMC proliferation, but the underlying molecular mechanism remains unclear. p21(Waf1/Cip1) is a potent inhibitor of cell cycle progression. Here, we demonstrate that amlodipine (10(-6) to 10(-8) M) activates de novo synthesis of p21(Waf1/Cip1) in vitro. We show that amlodipine-dependent activation of p21(Waf1/Cip1) involves the action of the glucocorticoid receptor (GR) and C/EBP-alpha. The underlying pathway apparently involves the action of mitogen-activated protein kinase or protein kinase C, but not of extracellular signal-related kinase or changes of intracellular calcium. Amlodipine-induced p21(Waf1/Cip1) promoter activity and expression were abrogated by C/EBP-alpha antisense oligonucleotide or by the GR antagonist RU486. Amlodipine-dependent inhibition of cell proliferation was partially reversed by RU486 at 10(-8) M (58%+/-29%), antisense oligonucleotides targeting C/EBP-alpha (91%+/-26%), or antisense mRNAs targeting p21(Waf1/Cip1) (96%+/-32%, n=6); scrambled antisense oligonucleotides or those directed against C/EBP-beta were ineffective. The data suggest that the anti-proliferative action of amlodipine is achieved by induction of the p21 (Waf1/Cip1) gene, which may explain beneficial covert effects of this widely used cardiovascular therapeutic drug beyond a more limited role as a vascular relaxant.

Amlodipine↗
PubMed2003

Vasoactive intestinal peptide as a new drug for treatment of primary pulmonary hypertension.

Primary pulmonary hypertension is a fatal disease causing progressive right heart failure within 3 years after diagnosis. We describe a new concept for treatment of the disease using vasoactive intestinal peptide, a neuropeptide primarily functioning as a neurotransmitter that acts as a potent systemic and pulmonary vasodilator. Our rationale is based on the finding of a deficiency of the peptide in serum and lung tissue of patients with primary pulmonary hypertension, as evidenced by radioimmunoassay and immunohistochemistry. The relevance of this finding is underlined by an upregulation of corresponding receptor sites as shown by Northern blot analysis, Western blot analysis, and immunological techniques. Consequently, the substitution with the hormone results in substantial improvement of hemodynamic and prognostic parameters of the disease without side effects. It decreased the mean pulmonary artery pressure in our eight study patients, increased cardiac output, and mixed venous oxygen saturation. Our data provide enough proof for further investigation of vasoactive intestinal peptide and its role in primary pulmonary hypertension.

Adult↗
PubMed2003

Long-term treatment with oral sildenafil in addition to continuous IV epoprostenol in patients with pulmonary arterial hypertension.

OBJECTIVES: To evaluate the effect of long-term oral therapy with sildenafil in patients with pulmonary arterial hypertension receiving long-term IV epoprostenol. DESIGN: Open, uncontrolled trial. SETTING: University hospital. PATIENTS: Two patients with primary pulmonary hypertension and one patient with pulmonary arterial hypertension after surgical closure of an atrial septal defect. All patients were receiving continuous epoprostenol for 1.7 to 7.1 years; two patients also received inhaled iloprost for 1.8 years and 3.8 years, respectively. INTERVENTIONS: Addition of oral sildenafil, up to 200 mg/d, divided in four to six single doses, and hemodynamic measurements and the 6-min walking distance (6MWD) before and after 5 months of treatment with sildenafil. RESULTS: One patient was treated with sildenafil, 200 mg/d; two patients received 75 mg/d due to nausea and headache. Long-term treatment with sildenafil in the three patients reduced mean pulmonary artery pressure by 14%, 41%, and 22%, respectively; in two patients, pulmonary vascular resistance was decreased by 52% and 55%. The 6MWD increased by 34%, 6%, and 29%, respectively. No significant systemic hypotension or decrease of arterial oxygen saturation was seen. CONCLUSION: Sildenafil therapy may be of benefit in patients with pulmonary arterial hypertension receiving long-term infusion of epoprostenol.

Administration, Oral↗