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V Petrova

Publications and source records attributed to V Petrova.

At least 19 recordsLinked to original sources
PubMed2002

Size-dependent detachment-limited decay kinetics of two-dimensional TiN islands on TiN(111).

In situ high-temperature (T(a)=1050-1250 K) scanning tunneling microscopy was used to determine the coarsening and decay kinetics of two-dimensional TiN adatom and vacancy islands on atomically smooth TiN(111) terraces. We report the first observation of an abrupt decrease in decay rates, irrespective of T(a), of adatom islands with areas less than a critical value of 1600 A(2). However, no decay rate transition was observed for vacancy islands. We attribute the size-dependent island decay behavior, which is consistent with detachment-limited kinetics, to anisotropic attachment and detachment barriers.

Journal Article↗
PubMed2002

Absolute TiN(111) step energies from analysis of anisotropic island shape fluctuations.

In situ high-temperature (1165-1248 K) scanning tunneling microscopy was used to measure fluctuations around the equilibrium shape of two-dimensional vacancy islands on TiN(111) terraces. From the equilibrium shape, the ratio of the two <110> step energies was found to be 0.72 +/- 0.02. Combining this with the results of an exact approach for analysis of shape fluctuations, applicable to highly anisotropic islands, we obtain absolute values for step energies and step stiffnesses as a function of orientation.

Journal Article↗
PubMed2000

Apolipoprotein E polymorphism and serum concentration in Alzheimer's disease in nine European centres: the ApoEurope study. ApoEurope group.

As part of the ApoEurope Project, apolipoprotein E (apo E) common polymorphism and serum concentration were determined in 489 Alzheimer's disease patients and 429 controls. Patients and controls were recruited through nine centres in eight European countries. Age, sex ratios and education levels of both case and control populations were similar, although discrete differences appeared between centres. The prevalence of the epsilon4 allele was higher in Alzheimer's disease than in controls (increased by 140%), while serum apo E concentration was lower by 11.2% (p<0.001). In addition, serum total cholesterol and triglyceride concentrations were lower in Alzheimer's disease (p<0.001), while that of apo Al was not affected. The decrease in serum apo E concentration was not accounted for by the epsilon4 allele, age or gender, suggesting that apo E concentration might represent an additional risk factor for Alzheimer's disease, complementary and independent of the epsilon4 allele. Further analysis will be aimed at determining whether the quantitative link between apo E concentration and Alzheimer's disease occurs through the effect of apo E genotype on lipid parameters or by other mechanisms.

Age Factors↗
PubMed1999

Estimation of trends of morbidity of colorectal cancer in Plovdiv district for the period from 1985 to 1996.

The present study concerns the incidence rate of colorectal cancer (CRC) in Plovdiv region (population 1,269,464). The study was carried out over a 12-year period and aimed at establishing the increase rate of this disease. Results show that incidence rate of CRC increased progressively for the mentioned period from 22.14 to 34.98 per 100,000 people and was almost twice as high as that for the country. It is a particularly disturbing fact that the morbidity and mortality rates due to colorectal cancer is rising--2.36 times for 12 years. We propose screening for asymptomatic and high risk patients with considerable results for opportune diagnostics.

Bulgaria↗
PubMed1999

Trends in the incidence of colorectal carcinoma in three regions of south Bulgaria for the period 1985-1998.

The purpose of the present study was to evaluate the increase of colorectal carcinoma incidence in three regions of South Bulgaria (a total population of 1,269,464 persons) over a 14-year period (1985-1998). The data about the incidence rate are retrieved from the oncological hospital records of the patients and Bulgarian National Oncological Register. The census data are provided by the National Institute of Statistics, Sofia. The results show that the incidence rate of colorectal carcinoma for the studied period increased steadily from 22.14/100,000 to 37.18/100,000 (an increment of 15.04/100,000) which is almost twice the average for the country. Compared to the baseline year of 1985 the increase in these three regions is 67.93% or approximately 5% annually. The incidence rate in Plovdiv region was almost twice that of Smolyan region. The incidence rate of colorectal carcinoma in both genders was greater than that of stomach cancer. The highest incidence rate was found in the 70-79-year-age group (193.5/100,000). A major part of our study was to find the stage in which colorectal carcinoma (CRC) is detected. In 1985 only 0.57% of the patients were diagnosed as being in the I-st clinical stage, 37.76%--in the II-nd, and 61.67%--in III-IV clinical stages. This unfavorable trend was preserved in 1998, when only 3.17% were diagnosed as having the first clinical stage, 38.62%--the II-nd and 58.21%--the III-IV clinical stages. The 14-year pronounced trend of increase of the prevalence rate (a 2.91 times increment) and the mortality rate (a 2.50 times increment) of colorectal carcinoma is especially alarming. We propose screening of the asymptomatic patients and high-risk persons which gives considerable results in the timely diagnostics of colorectal carcinoma.

Adult↗
PubMed1995

The pleckstrin homology domain of phospholipase C-delta 1 binds with high affinity to phosphatidylinositol 4,5-bisphosphate in bilayer membranes.

The pleckstrin homology (PH) domain of phospholipase C-delta 1 (PLC-delta 1) binds to phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) in phospholipid membranes with an affinity (Ka approximately 10(6) M-1) and specificity comparable to those of the native enzyme. PLC-delta 1 and its PH domain also bind inositol 1,4,5-trisphosphate, the polar head group of PI(4,5)P2, with comparable affinity and approximately 1:1 stoichiometry. A peptide corresponding to amino acids 30-43 of the PLC-delta 1 PH domain contains several basic residues predicted to bind PI(4,5)P2, but binds weakly and with little specificity for PI(4,5)P2; hence the tertiary structure of the isolated PH domain is required for high affinity PI(4,5)P2 binding. Our PI-(4,5)P2 binding results support the hypothesis that the intact PH domain, serving as a specific tether, directs PLC-delta 1 to membranes enriched in PI(4,5)P2 and permits the active site, located elsewhere in the protein, to hydrolyze multiple substrate molecules before this enzyme dissociates from the membrane surface.

Amino Acid Sequence↗
PubMed1992

[Lipid and mineral metabolism and morbidity with temporary loss of work capacity in miners].

Examination is performed on 87 miners from mine for copper production subject to intensive local vibrations with average rate of increase (K) of the norms for the individual octave frequencies 2.4 times for 3 h exposure of the working shift, as well as to intensive noise--113-115 dB/A equivalent level, general dust--23 mg/m3, fine dust--3.5 mg/m3 and fine quartz--0.43 mg/m3. There are data for vibration effect--changes in the cold test, vibration sensoriness, ultra sound sonometry, in all miners. In a significant part of them are established dyslipoproteinemia--increase of triglycerides, total and LDL cholesterol, values beyond reference (mainly above the norm) of 10 electrolytes and microelements in blood serum (blood). An extremely high prevalence of the cases and the days of total morbidity with temporary disability (respectively 189.7 and 2935 per 100), with predominance in its structure of diseases of the central and peripheral nervous systems, hypertension disease, etc. The importance of vibrations for disorder in the metabolic processes in the organism and development of temporary diseases are underlined.

Absenteeism↗
PubMed1991

[Gemfibrozil in the treatment of hyperlipoproteinemias].

30 patients with primary hyperlipoproteinemia (type II and IV according to Fredrickson) were treated with Gemfibrosil (Gevinon--film tablets of 450 mg of "Parke-Davis Company") for a period of 45 days with a daily dose of two tablets taken with the evening meal. The results of the treatment were a decrease of the total cholesterol (with 16.34%), of triglycerides (with 34.50%), of low density lipoproteins (with 10.76%) and of very low density lipoproteins (with 49.21%) and an increase of the high density lipoproteins (with 2.34%). Gevilon was well tolerated. No side effects requiring discontinuing of the treatment were registered.

Adult↗
PubMed1990

[Epidemiological examinations of the workers at a thermoelectric power station].

Medical and clinico-laboratory examinations were performed of thermoelectric power station (TES) workers who were exposed to the hazardous factors related to the technological process and contamination substances transferred from other industrial sites. Following prepathologic and pathologic states were registered: respiratory functional disorders, ischemic heart disease, arterial hypertension, audiometric state deviations and acoustic nerve neuritis, irritative dermatitis. Basing on the data obtained, risk groups identification was performed.

Absenteeism↗
PubMed1990

[Changes in the high-density lipoprotein level in patients with diabetes mellitus type II].

In 62 patients with diabetes mellitus type II, 22 patients with obesity I degree and 40 patients with normal body mass (28 with ischemic heart disease and 12 without ischemic heart disease) the blood sugar profile and the composition of the high density lipoproteins (HDL) were examined. In decompensated diabetes mellitus type II reduction of cholesterol and phospholipid contents of HDL and of apoprotein A were found. With compensation of the carbohydrate metabolism the composition of HDL becomes normal. In the obese diabetics the changes of these indices are more pronounced. In diabetic patients with ischemic heart disease the cholesterol and phospholipid contents and that of apoprotein A in HDL are lower than those in diabetic patients without ischemic heart disease. These data show that changes of HDL in diabetes mellitus favor the development of atherosclerosis changes.

Adult↗
PubMed1989

[The effect of vitaton on a model of isoprenaline myocardiopathy in rats].

The influence of the combined preparation vitaton (Pharmachim) was studied on some functional, biochemical and morphological changes, induced after four-fold subcutaneous administration of 100 mg/kg of isoprenaline. The experiments were carried out on three groups: control nontreated, control treated with isoprenaline and experimental, treated simultaneously with isoprenaline and 500 mg/kg of vitalon, administered orally. The preparation was used 3 days before and 2 days after the administration of isoprenaline. Evaluation of the preparation action was made by the following parameters: ECG in the II standard lead, effect on serum level of cholesterol, triglycerols, cholesterol and lipoproteins with high, low and very low density, enzymic activity of hydroxybutiroldehydrogenase (HBDH), creatinephosphokinase (CPK), aspartataminotransferase (ASAT) and alaninaminotransferase (ALAT). Pathomorphological and morphometric studies of the hearts were performed as well. The results from the conducted experiments showed that vitaton reduced pathological changes in the electrocardiographic recordings as well as the abnormal increase in cholesterol and fractions of lipoproteins with low density. Beside this it lowered considerably the enzymic activity, observed under the influence of isoprenaline. The preparation diminished the area of myocardial damage more than twice, estimated by the index of the myocardial damage. The effect of vitalon on the model of isoprenaline myocardiopathy could be explained by its metabolic action and more exactly by its influence on protein synthesis and on lipid metabolism.

Animals↗
PubMed1989

[Unsaturated fatty acids in diabetes mellitus].

The following unsaturated fatty acids were examined in the serum and in the high density lipoproteins of 38 patients with diabetes mellitus type Il and 20 healthy controls: linolic, linolenic, eicosandienoic, eicosanetrienoic, arachidonic and eicosanepentaenoic. In decompensates diabetes mellitus a decrease of linolenic, eicosanedienoic, arachidonic and eicosanepentaenoic acids and an increase of linolic and eicosanetrienoic acids were found. After compensation of carbohydrate metabolism the last fatty acids showed a tendency toward normalization. The parallel changes of the fatty acids studied in the serum and in the high density lipoproteins suggest that the fatty acids contents of the HDL depends on the serum fatty acids. It is most probable that the variable changes of the individual unsaturated fatty acids play a role in the complex mechanism of vascular lesions in diabetes mellitus.

Aged↗
PubMed1989

[Moniside (isosorbide-5-mononitrate)--the effect on some changes in a hyperlipoproteinemia mode in rats].

The influence of the preparation moniside (isosorbide-5-mononitrate on some functional, lipid and enzymic changes in a model of hyperproteinemia of rats was investigated. Studies were carried out on 45 male rats, divided into 3 groups: I group-control, nontreated; II group--control treated with cholesterol diet; III group--experimental treated with cholesterol diet and monoside in a dose of 20 mg/kg of body weight orally 6 days a week. The experiment continued 3 months. Changes in general state, body mass, static physical endurance, stability to electric current were described as well as the following lipid parameters: cholesterol (mmol/l), cholesterol in lipoproteins with high density (LHD), cholesterol in lipoproteins with low and very low density (LLD, LVLD), tryglycerols (Tr), free fatty acids (FFA). Changes in enzymic activity of aspartataminotransferase (ASAT), alaninamidotransferase (AlAt), hydroxybutiratdehydrogenase (HBDH) and creatinphosphokinase (CPK). Morphological examinations of heart, aorta, liver, kidneys and adrenal were made as well. The results from the experiments showed that in a model with hyperlipoproteinemia general state of experimental animals was impaired, body mass was reduced, physical endurance and stability to electric current reduced, while cholesterol and LVLD/were increased, AlAt increased mult many times, but HBDH and CPK diminished their activity. Functional possibilities of the organism increased at a slight degree under the influence of monoside. Lipid changes, established after cholesterol diet, did not change substantially, while deviations in enzymic activity were normalized.

Animals↗
PubMed1988

[Lipoprotein and apoprotein changes in type-2 diabetes mellitus].

Lipid metabolism indices were followed up in 62 patients with diabetes mellitus type II and in 20 healthy persons as controls. An increase of serum triglycerides, very low density lipoproteins and low density lipoproteins, a decrease of high density lipoproteins and cholesterol in the upper reference range were found. Following diabetes compensation these indices became normal. In decompensated diabetes apoprotein A increased, apoprotein B decreased. Diabetes compensation lead to normalization of these indices. A comparative study of these indices in diabetics with and without ischemic heart disease was carried out. It showed a considerable decrease of the high density lipoproteins and a parallel increase of the very low density lipoproteins and low density lipoproteins in the diabetics with ischemic heart disease. The results of the study lead to the conclusion that criterion for diabetes compensation should be not only the blood sugar normalization bur also the correction of the lipid fractions changes.

Adult↗
PubMed1988

[Fatty acids in diabetes mellitus].

In 38 patients with diabetes mellitus type II and in 20 healthy controls the total amount of saturated and unsaturated fatty acids was examined in the serum and in the high density lipoproteins (HDL) as well as the following fatty acids: palmitic, stearic, oleic and arachidonic. In decompensated diabetes an increase of the saturated fatty acids with a parallel decrease of the unsaturated fatty acids were found in the serum and in the HDL. The compensation of the diabetes led to normalization of the ratio between the saturated and unsaturated fatty acids. In decompensated diabetes an increase of the palmitic and stearic acids with a parallel decrease of the oleic and arachidonic acids were found. After compensation of the diabetes was achieved the fatty acids levels became normal again. Knowing the role of the fatty acids in the atherogenesis it may be assumed that the changes of the fatty acids levels in diabetes mellitus contribute to the vascular lesions.

Aged↗
PubMed1987

[Non-enzymatically glycosylated low-density lipoproteins in diabetes mellitus].

In 24 diabetic patients and 23 healthy persons the fatty metabolism was studied (cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol and glycosylated LD-lipoproteins). Iin diabetic patients the glycosylated low density lipoproteins travel from the cathode to the anode at a distance of 37-57 mm and in the control group they travel to a distance of 18-22 mm. In spite of the insignificant differences of cholesterol levels between the diabetics and the control and of the total cholesterol level being in normal ranges, the nonenzymatically glycosylated LD-lipoproteins are in greater quantity in the diabetics which is a predisposing factor for early atherosclerosis. The establishment of a correlation between the blood sugar level and that of the glycosylated LD-lipoproteins in diabetic patients could serve as a criterion for early atherosclerosis.

Adult↗