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Biomedical subjects

V Petkov

Publications and source records attributed to V Petkov.

At least 19 recordsLinked to original sources
PubMed2003

Controlled prospective randomised trial on the effects on pulmonary haemodynamics of the ambulatory long term use of nitric oxide and oxygen in patients with severe COPD.

BACKGROUND: Pulmonary hypertension is a frequent complication of severe chronic obstructive pulmonary disease (COPD) and a major cause of morbidity and mortality in this condition. Based on the improved survival of these patients due to long term oxygen therapy and the potent and selective pulmonary vasodilation by inhaled nitric oxide, the safety and effectiveness of the combined inhalation of these two gases over a 3 month period was assessed. METHODS: Forty patients with secondary pulmonary hypertension due to COPD were randomly assigned to receive either oxygen alone or "pulsed" inhalation of nitric oxide with oxygen over a period of 3 months. "Pulsed" inhalation of nitric oxide was used to reduce pulmonary ventilation-perfusion mismatch and formation of toxic reaction products of nitric oxide and oxygen. RESULTS: Compared with oxygen alone, the combined inhalation of nitric oxide and oxygen caused a significant decrease in mean (SE) pulmonary artery pressure (from 27.6 (4.4) mm Hg to 20.6 (4.9) mm Hg, p<0.001) and pulmonary vascular resistance index (from 569.7 (208.1) to 351.3 (159.9) dyne x s(-1) x cm(-5) x m(-2), p<0.001) without decreasing arterial oxygenation. Cardiac output increased by 0.5 litres (from 5.6 (1.3) l/min to 6.1 (1.0) l/min, p=0.025). Systemic haemodynamics and left heart function remained unchanged during this period and no increase in toxic reaction products of nitric oxide was observed. CONCLUSIONS: This is the first controlled trial indicating that the "pulsed" inhalation of nitric oxide together with oxygen may be safely and effectively used for the long term treatment of severe COPD.

Administration, Inhalation↗
PubMed2002

Structure of intercalated Cs in zeolite ITQ-4: an array of metal ions and correlated electrons confined in a pseudo-1D nanoporous host.

The presence of Cs+ ions in the pseudo-1D nanopores of zeolite ITQ-4, Si32O64, is confirmed by x-ray diffraction and atomic pair distribution function analysis. Inside the nanopores the Cs+ ions are found to assemble in zigzag chains and thus form an extended, positively charged sublattice providing charge balance for a low-density electron gas also confined to the nanopores.

Journal Article↗
PubMed2002

[Pathogen resistance and other risk factors in the frequency of lower limb amputations in patients with the diabetic foot syndrome].

UNLABELLED: Patients with diabetes mellitus undergo more amputations due to peripheral vascular disease, neuropathy and especially to infection requiring long-lasting antibiotic therapy than non diabetic patients. The aim of our study was to assess the association between the presence of resistant pathogens presented in diabetic ulcers and the frequency of lower limb amputations. METHODS: 191 diabetic patients consecutively treated for the diabetic foot in our foot clinic were included into two years retrospective study. Peripheral ischemia, the presence of osteomyelitis and the incidence of all Gram positive and negative resistant pathogens (defined as resistance to all oral antibiotics) especially of resistant Staphylococcus species presenting in diabetic foot ulcers were determined. RESULTS: 50/191 (26%) patients underwent amputation, of whom 44/50 (88%) had minor and 6/50 (12%) had major amputations. 53/181 (29%) patients with diabetic foot ulcers had resistant pathogens in their defects. Amputated patients had significantly more resistant microorganisms than patients without amputations--24/42 (57%) vs. 29/139 (21%); p < 0.001. Resistant Staphylococcus species were found in 21% (38/181) of all patients. Patients with amputations had significantly more resistant Staphylococcus species in comparison with patients without amputations--18/42 (43%) vs. 20/139 (14%); p < 0.001. Significantly higher incidence of peripheral vascular disease--79% (38/48) vs. 60% (81/136); p < 0.05 and osteomyelitis--69% (33/48) vs. 13% (18/140); p < 0.001--were found in patients with amputations in comparison with patients without amputations. CONCLUSION: The presence of pathogens resistant to all oral antibiotics and especially of resistant Staphylococcus species was significantly higher in diabetic patients with lower limb amputations in comparison with patients without amputations.

Amputation, Surgical↗
PubMed2001

Aerosolised iloprost improves pulmonary haemodynamics in patients with primary pulmonary hypertension receiving continuous epoprostenol treatment.

BACKGROUND: Continuous intravenous treatment with epoprostenol significantly improves pulmonary haemodynamics and survival in patients with primary pulmonary hypertension (PPH). Its beneficial effect, however, may be blunted due to adverse effects such as catheter sepsis and systemic hypotension. Recent investigations have shown that inhaled iloprost is effective in the treatment of PPH. Based on their different pharmacokinetics, we hypothesised that the combination of intravenous epoprostenol and inhaled iloprost would be more efficacious than epoprostenol alone during acute testing in patients with PPH. METHODS: The effect of a single dose of inhaled iloprost (30 microg total over 15 minutes) on pulmonary haemodynamics was examined in eight patients with PPH (initial non-responders to nitric oxide) who had considerable adverse effects during treatment with epoprostenol. RESULTS: The combination of inhaled iloprost and intravenous epoprostenol significantly improved mean pulmonary artery pressure (MPAP), cardiac index (CI), mixed venous oxygen saturation (SvO2), and systemic arterial oxygen pressure (PaO2) compared with epoprostenol treatment alone. Mean systemic arterial pressure (MSAP) and pulmonary capillary wedge pressure (PCWP) remained unchanged. CONCLUSIONS: The pulmonary vasoreactivity shown by additional iloprost inhalation during effective epoprostenol treatment suggests that an improvement of treatment for pulmonary hypertension may be possible by combining vasoactive substances.

Administration, Inhalation↗
PubMed2001

Long-term treatment of pulmonary hypertension with aerosolized iloprost.

Pulmonary arterial hypertension (PAH), defined as elevated pulmonary arterial pressure and pulmonary vascular resistance, is an end-point of a variety of conditions. The only therapy that has been shown to improve both quality of life and survival is intravenous prostacyclin (prostaglandin I2 (PGI2), epoprostenol). The effect of long-term aerosolized iloprost (Ilomedin, Schering, Berlin, Germany and Vienna, Austria), a stable prostacyclin analogue and potent vasodilator, on haemodynamics and functional status was investigated in 12 patients with severe pulmonary hypertension. Haemodynamic measurements and vasodilator testing by right heart catheterization were performed prior to and after long-term iloprost inhalation therapy. Haemodynamic improvement or increased exercise tolerance was not observed in any of the patients. After a mean+/-SD treatment period of 10+/-5 months, mean+/-SD pulmonary vascular resistance had increased from 11+/-3 Wood Units (mmHg.L(-1).min) to 13+/-4 Wood Units, with unchanged arterial oxygen saturation (92+/-4%, versus 91+/-4%). Within the study period, three patients went into right heart failure and had to be placed on intravenous epoprostenol. The authors conclude that inhaled iloprost in addition to conventional therapy in the presently recommended dose of 100 microg.day(-1) delivered in 8-10 2 h portions, is not an efficient vasodilator therapy in severe pulmonary hypertension. It remains to be shown whether dose increases and/or combination protocols will be effective, or whether inhalation of iloprost may be safe for selected cases of pulmonary hypertension.

Administration, Inhalation↗
PubMed2001

Aerosolized iloprost therapy could not replace long-term IV epoprostenol (prostacyclin) administration in severe pulmonary hypertension.

OBJECTIVES: To switch patients with severe pulmonary hypertension and previous life-threatening catheter-related complications from long-term IV epoprostenol therapy to aerosolized iloprost therapy. DESIGN: Open, uncontrolled trial. SETTING: Medical ICU of a university hospital. PATIENTS: Two patients with primary pulmonary hypertension and one patient with pulmonary hypertension after surgical closure of atrial septal defect (mean pulmonary artery pressure > or =50 mm Hg). All were classified as New York Heart Association class II under treatment with continuous IV epoprostenol for 4 years. INTERVENTIONS: Stepwise reduction of IV epoprostenol (1 ng/kg/min steps every 3 to 10 h) during repeated inhalations of aerosolized iloprost (150 to 300 microg/d with 6 to 18 inhalations/d). Continuous pulmonary and systemic arterial monitoring were performed. RESULTS: Aerosolized iloprost reduced pulmonary artery pressure by 49%, 49%, and 45%, respectively, and increased cardiac output by 70%, 75%, and 41% in the three patients. The effect lasted for 20 min and was similar at different doses of IV epoprostenol. Persistent treatment change to inhaled iloprost could not be achieved because all patients developed signs of right heart failure. After termination of iloprost inhalations, return to standard epoprostenol therapy led to clinical and hemodynamic restoration. CONCLUSIONS: Although aerosolized iloprost demonstrated short-term hemodynamic effects, it could not be utilized as alternative chronic vasodilator in patients with severe pulmonary hypertension.

Administration, Inhalation↗
PubMed2001

111In-DOTA-lanreotide scintigraphy in patients with tumors of the lung.

UNLABELLED: Imaging with radiolabeled somatostatin (SST) analogs has recently been established for the localization of various human SST receptor (hsstr)-positive tumors, including neuroendocrine tumors, lymphomas, and non-small cell lung cancer (NSCLC). METHODS: 111In-1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid-lanreotide (DOTA-LAN) scintigraphy (150 MBq; 7 nmol per patient) was performed on 47 patients (28 patients with primary tumors, 19 patients with lung metastases from other tumors) to evaluate the tumor binding in patients with histologically confirmed lung cancer. A group of 27 tumor patients without documented lung lesions served as the control group. Early and delayed planar and SPECT images were acquired. Whole-body scintigraphy was performed at 0.5, 4-6, 24, and 48 h after injection for tumor dose estimation. In addition, hsstr subtype expression and radioligand binding characteristics were studied in vitro using lung tumor samples (n = 15). RESULTS: 111In-DOTA-LAN indicated the primary lung tumor in 16 of 16 NSCLC patients. Lymph node metastases were visualized in 6 of 6 NSCLC patients, and bone metastases were seen in 3 of 3 NSCLC patients. 111In-DOTA-LAN scintigraphy indicated lung carcinoid in 5 of 5 patients and small cell lung cancer lesions in 6 of 6 patients. Multiple lung metastases were shown in all 6 patients with non-Hodgkin's lymphoma and in the 1 patient with Hodgkin's disease, 5 of 5 colorectal adenocarcinoma patients, 4 of 4 carcinoid patients, 2 of 2 neuroendocrine carcinoma (NEC) patients, and 1 of 1 angiosarcoma patient. Pulmonary tumor sites not indicated by CT or MRI were visualized in 6 of 47 tumor patients (i.e., 13%; lung metastases in 1 carcinoid patient and 1 NEC patient, lymph node metastases in 1 carcinoid patient and 2 NSCLC patients, bone metastases in 1 carcinoid patient). The estimated lung tumor dose ranged between 0.2 and 5 mGy/MBq. Focal lung uptake of 111In-DOTA-LAN was not observed in any of the 27 control patients. In vitro binding studies indicated high-affinity binding sites for 111In-DOTA-LAN in NSCLC samples (dissociation constants, 0.5 and 4 nmol/L) with predominant expression of hsstr4. CONCLUSION: 111In-DOTA-LAN yields high tumor binding for various human lung tumors. Consecutively, radiopeptide therapy may offer a potential new treatment alternative for some lung tumor patients.

Case-Control Studies↗
PubMed2000

Polyhedral units and network connectivity in calcium aluminosilicate glasses from high-energy X-Ray diffraction

Structure factors for Ca (x/2)Al xSi 1-xO (2) glasses (x = 0,0.25,0. 5,0.67) extended to a wave vector of magnitude Q = 40 A (-1) have been obtained by high-energy x-ray diffraction. For the first time, it is possible to resolve the contributions of Si-O, Al-O, and Ca-O coordination polyhedra to the experimental atomic pair distribution functions. It has been found that the connectivity of Si/Al-O tetrahedral network decreases with increasing x due to the emerging of nonbridging oxygens located on Si-O tetrahedra. Calcium maintains a rather uniform coordination sphere for all values of x and so it plays a certain role in determining the glass structure.

Journal Article↗
PubMed2000

Treatment with epoprostenol reverts nitric oxide non-responsiveness in patients with primary pulmonary hypertension.

OBJECTIVE: To assess whether long term treatment with epoprostenol might restore primary non-responsiveness to nitric oxide (NO) in patients with primary pulmonary hypertension. METHODS: Seven patients with primary pulmonary hypertension receiving intravenous epoprostenol continuously because of failure of NO to influence pulmonary haemodynamics during initial testing were followed over a period of 13-29 months. Afterwards, acute vascular reactivity towards NO was tested again during right heart catheterisation. RESULTS: Administration of NO after continuous epoprostenol treatment for a mean period of 18 months improved arterial oxygen saturation (p < 0.01) and cardiac index (p < 0.05), and decreased mean pulmonary artery pressure (p < 0.01) and total pulmonary vascular resistance (p < 0.01) in patients previously unresponsive to NO. CONCLUSIONS: Long term treatment with epoprostenol reverts initial refractoriness to NO in patients with primary pulmonary hypertension. Thus the addition of NO to epoprostenol treatment might cause further improvement in the course of the disease.

Adult↗
PubMed1999

A preliminary study of long-term treatment with interferon gamma-1b and low-dose prednisolone in patients with idiopathic pulmonary fibrosis.

BACKGROUND AND METHODS: Patients with idiopathic pulmonary fibrosis have progressive scarring of the lung and usually die within four to five years after symptoms develop. Treatment with oral glucocorticoids is often ineffective. We conducted an open, randomized trial of treatment with a combination of interferon gamma-1b, which has antifibrotic properties, and an oral glucocorticoid. We studied 18 patients with idiopathic pulmonary fibrosis who had not had responses to glucocorticoids or other immunosuppressive agents. Nine patients were treated for 12 months with oral prednisolone alone (7.5 mg daily, which could be increased to 25 to 50 mg daily), and nine with a combination of 200 microg of interferon gamma-1b (given three times per week subcutaneously) and 7.5 mg of prednisolone (given once a day). RESULTS: All the patients completed the study. Lung function deteriorated in all nine patients in the group given prednisolone alone: total lung capacity decreased from a mean (+/-SD) of 66+/-8 percent of the predicted value at base line to 62+/-6 percent at 12 months. In contrast, in the group receiving interferon gamma-1b plus prednisolone, total lung capacity increased (from 70+/-6 percent of the predicted value at base line to 79+/-12 percent at 12 months, P<0.001 for the difference between the groups). In the group that received interferon gamma-1b plus prednisolone, the partial pressure of arterial oxygen at rest increased from 65+/-9 mm Hg at base line to 76+/-8 mm Hg at 12 months, whereas in the group that received prednisolone alone it decreased from 65+/-6 to 62+/-4 mm Hg (P<0.001 for the difference in the change from baseline values between the two groups); on maximal exertion, the value increased from 55+/-6 to 65+/-8 mm Hg in the group that received combined treatment and decreased from 55+/-6 mm Hg to 52+/-5 mm Hg in the group given prednisolone alone (P<0.001). The side effects of interferon gamma-1b, such as fever, chills, and muscle pain, subsided within the first 9 to 12 weeks. CONCLUSIONS: In a preliminary study, 12 months of treatment with interferon gamma-1b plus prednisolone was associated with substantial improvements in the condition of patients with idiopathic pulmonary fibrosis who had had no response to glucocorticoids.

Carrier Proteins↗
PubMed1999

Positron emission tomography with fluorine-18-2-fluoro-2-deoxy-D-glucose (F18-FDG) does not visualize extranodal B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT)-type.

BACKGROUND: On the basis of promising data on the use of fluorine-18-2-fluoro-2-deoxy-D-glucose (F18-FDG) whole body positron emission tomography (WB-FDG-PET) in the staging of patients with lymphoma, we initiated a pilot series to evaluate the role of WB-FDG-PET in the staging of extranodal B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) type. PATIENTS AND METHODS: We examined ten consecutive patients with histologically-verified MALT-type lymphomas of various origin before initiation of therapy. Nine patients had low-grade lymphomas (five cases of gastric lymphoma, two patients with lymphoma arising in the lung, one parotid and one lacrimal gland lymphoma), while one patient had a high-grade gastric lymphoma arising from a low-grade background. Two patients had stage EI, seven had stage EII disease, and one presented with stage EIII. WB-FDG-PET scans were performed 40 min following the injection of 300-380 MBq of F18-FDG. The PET scans were correlated with extensive conventional staging including ophthalmologic investigation, otolaryngologic examination, gastroscopy, endosonography, enteroclysis, colonoscopy, CT of thorax and abdomen, and bone marrow biopsy. RESULTS: WB-FDG-PET documented no lymphoma in any of the 10 patients studied, as no focal tracer uptake was demonstrated in either gastric or extragastric lesions or in involved lymph nodes, irrespective of histologic grading. In three patients the scan showed a false negative result with respect to the MALT lesions but showed focal tracer uptake indicating tumor spread, which, however, was ruled out by further follow-up and biopsy, respectively, and was thus rated false positive. Due to these results, the study was discontinued prematurely after the first ten patients. CONCLUSIONS: These discouraging results indicated that WB-FDG-PET is not useful for staging and follow-up of MALT-type lymphoma, and should therefore not be included in the clinical decision making process.

Aged↗
PubMed1996

Lipopolysaccharide and interleukin 1 augment the effects of hypoxia and inflammation in human pulmonary arterial tissue.

The combined effects of hypoxia and interleukin 1, lipopolysaccharide, or tumor necrosis factor alpha on the expression of genes encoding endothelial constitutive and inducible nitric oxide synthases, endothelin 1, interleukin 6, and interleukin 8 were investigated in human primary pulmonary endothelial cells and whole pulmonary artery organoid cultures. Hypoxia decreased the expression of constitutive endothelial nitric oxide synthase (NOS-3) mRNA and NOS-3 protein as compared with normoxic conditions. The inhibition of expression of NOS-3 corresponded with a reduced production of NO. A combination of hypoxia with bacterial lipopolysaccharide, interleukin 1 beta, or tumor necrosis factor alpha augmented both effects. In contrast, the combination of hypoxia and the inflammatory mediators superinduced the expression of endothelin 1, interleukin 6, and interleukin 8. Here, we have shown that inflammatory mediators aggravate the effect of hypoxia on the down-regulation of NOS-3 and increase the expression of proinflammatory cytokines in human pulmonary endothelial cells and whole pulmonary artery organoid cultures.

Blotting, Northern↗
PubMed1993

Characteristic features of HIV/AIDS in the Czech Republic.

First laboratory proved HIV infections in the Czech Republic were diagnosed in a homosexual couple in autumn of 1985. Total number of detected HIV+ cases reached 143 persons by the end of 1992 (132 men and 11 women), of that 31 cases were classified as fully blown AIDS (21 already died). Out of these 143 HIV+ cases, 93 (65.0%) are represented by homo/bisexuals, 10 (7.0%) by heterosexuals, 16 (11.2%) by haemophiliacs, 14 (9.8%) by blood recipients, 1 (0.7%) by IVDU and 9 (6.3%) by unknown transmission category. Approx. 2.1 mil. of tests have been done as routine screening of donated blood. Only 5 cases (0.0002%) of HIV positivity have been found in this group. All HIV positive blood recipients (30 cases) were infected before the mandatory HIV testing of blood supply has been introduced in 1987 (14 out of 16 HIV+ haemophiliacs were infected by imported clotting products). The twins born in 1990 to mother infected by contaminated blood in 1984, were declared at the age of 30 months as HIV free, with all laboratory tests (serology, virus cultivation, PCR) negative. The cummulative infection rate of HIV antibody in 1986-1992 reached 13.8 per million inhabitants. It may be concluded that slow steady increase in the number of reported HIV/AIDS cases has been registered during the whole follow-up period. The authors are aware that relatively low prevalence of HIV infection in the Czech Republic may change dramatically in consequences of recent deep social, political and economical changes in the country.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[The expert diagnosis of HIV infection by radioimmunoprecipitation].

Using a panel of sera from HIV-infected persons and donors, the authors showed that radioimmunoprecipitation assays compare favourably with immunoblotting assays. With radioimmunoprecipitation, cross reactions were observed between HIV-2 antigens and HIV-2 antibodies, and that the nature of cross reactivity differs from that observed with immunoblotting. Potentials of radioimmunoprecipitation assays as a confirmatory test for use with sera that have given indeterminate results in immunoblotting assays and contradictory results in enzyme immunoassays are examined.

AIDS Serodiagnosis↗
PubMed1990

[Dynamics of the antibody response and p24 antigenemia in HIV-1 infected individuals in Czechoslovakia].

In a group of 83 anti HIV-1 positive subjects the antibody response against different structural viral proteins was investigated concurrently with assessment of p 24 antigenaemia. Disappearance of antibodies against the capsidal antigen p 24 was recorded in 12% of 42 patients with ARC and AIDS. On the other hand, these antibodies persisted in all 41 asymptomatic infections throughout the three-year investigation period. Disappearance of antibodies against p 17 antigen was proved in 41% of the patients and in 22 subjects without clinical symptoms. The authors found a rising trend of antigenaemia p 24 in the course of HIV infection. The free p 24 antigen was detected in 62% patients with AIDS and only in 10% asymptomatic infections. The investigation confirmed the importance of investigations of the antibody response and p 24 antigenaemia in the prognosis of development of HIV infection and in monitoring of the effect of therapy.

AIDS-Related Complex↗
PubMed1990

[Detection of HIV infection using the immunofluorescence test].

The author examined, using the immunofluorescence test, 107 ant HIV positive sera and 114 sera with false reactions in the ELISA test. He proved a high sensitivity and specificity of the immunofluorescence test in the detection of anti-HIV antibodies, comparable with Western-blot's technique and he established the value of the immunofluorescence test for the identification of the virus antigen on isolation of the virus from HIV infected patients.

AIDS Serodiagnosis↗
PubMed1990

[Cultivation of HIV-1 virus on mononuclear peripheral blood cells of HIV-1 seropositive individuals].

Using the method of co-cultivation with phytohaemagglutinin-stimulated lymphocytes from healthy donors, the author isolated the HIV-1 virus from peripheral mononuclear blood cells of three patients with the AIDS symptomatology and one patient with the ARC symptomatology. The presence of the virus in infected cells was proved by detection of the viral antigen p 24 in enzymatic immunoassays and in the immunofluorescence test. Three of the isolated strains were adapted to sensitive continual tissue cultures, where the isolates caused chronic infection of the cells associated with the development of a cytopathic effect. In the investigated patients no relationship was proved between viraemia and antigenaemia. The author discusses the importance of virus cultivation for laboratory diagnosis, epidemiology and research of HIV infection and AIDS.

AIDS-Related Complex↗