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Biomedical subjects

J Petrásek

Publications and source records attributed to J Petrásek.

At least 19 recordsLinked to original sources
PubMed2006

ARP2 and ARP3 are localized to sites of actin filament nucleation in tobacco BY-2 cells.

Complete depolymerization of actin filaments (AFs) at low temperature (0 degrees C) is followed by the formation of transient actin structures at 25 degrees C in tobacco BY-2 cells (Nicotiana tabacum L.). Using antibodies against fission yeast actin-related proteins (ARP2 and ARP3), we show here that transient actin structures (dots, dotted filaments, rods) colocalize with epitopes stained by these antibodies and thus are likely to represent sites of actin filament nucleation (SANs). In contrast to the cold-induced disassembly of AFs, no transient actin structures were detectable during recovery of AFs from latrunculin B-induced depolymerization. However, the staining pattern obtained with ARP antibodies in latrunculin B-treated cells was similar to that in controls and cold-treated cells. This suggests that, in addition to the complete depolymerization of AFs, disruption of other cellular structures is needed for the formation of transient actin structures during the early phase of recovery from cold treatment.

Actin Cytoskeleton↗
PubMed2006

Intranuclear accumulation of plant tubulin in response to low temperature.

Concurrently with cold-induced disintegration of microtubular structures in the cytoplasm, gradual tubulin accumulation was observed in a progressively growing proportion of interphase nuclei in tobacco BY-2 cells. This intranuclear tubulin disappeared upon rewarming. Simultaneously, new microtubules rapidly emerged from the nuclear periphery and reconstituted new cortical arrays, as was shown by immunofluorescence. A rapid exclusion of tubulin from the nucleus during rewarming was also observed in vivo in cells expressing GFP-tubulin. Nuclei were purified from cells that expressed GFP fused to an endoplasmic-reticulum retention signal (BY-2-mGFP5-ER), and green-fluorescent protein was used as a diagnostic marker to confirm that the nuclear fraction was not contaminated by nuclear-envelope proteins. These purified, GFP-free nuclei contained tubulin when isolated from cold-treated cells, whereas control nuclei were void of tubulin. Furthermore, highly conserved putative nuclear-export sequences were identified in tubulin sequences. These results led us to interpret the accumulation of tubulin in interphasic nuclei, as well as its rapid nuclear export, in the context of ancient intranuclear tubulin function during the cell cycle progression.

Amino Acid Sequence↗
PubMed2002

[Carotid sonography and measurement of intima-medial thickness as indicators for risk of systemic atherosclerosis].

Ultrasound of carotid arteries belongs to non-invasive, safe, and comparatively inexpensive methods of the subclinical phase arteriosclerosis detection. It allows identification of atherosclerosis plaques, which can be found in higher numbers in elderly persons. Measurement of intima-media thickness (IMT) belongs to the time-proven methods and it represents an independent indicator of the risk of the cerebro-vascular event, coronary event including the myocardial infarction, and lower limbs ischaemic disease. In asymptomatic forms in persons over 45 years, the meticulous IMT examination can bring an additional information on the traditional risk factors, specify further the risks of cardio-vascular events, and help to elaborate the extent of preventive measures.

Aged↗
PubMed1999

The effect of four-year hypolipidaemic treatment on the intimal thickness of the common carotid artery in patients with familiar hyperlipidaemia.

BACKGROUND: Cholesterol lowering in patients with above-average cholesterol levels has been shown to reduce the progression of atherosclerosis. We assess the effects of lipid lowering therapy on the progression of early, preintrusive carotid arterial atherosclerosis in high risk patients with familial hyperlipidaemia free of symptomatic cardiovascular disease. METHODS: Fifty-two patients with familial hyperlipidaemia by were treated by diet and various hypolipidaemic drugs. Eighteen individuals were not taking hypolipidaemic drugs. In a prospective study by B-mode ultrasound we assessed the intima-media thickness of the distal common carotid arterial (CCA) far wall at baseline and after 4 years. RESULTS: In a subgroup of 25 patients with familial hypercholesterolaemia there was a significant decrease in total and LDL cholesterol and reduction in the intima-media thickness (IMT) of the common carotid artery from 0.78+/-0.22 mm to 0.69+/-0.17 mm (p=0.004). In a subgroup of 27 patients with familial combined hyperlipidaemia significant decreases in total and LDL cholesterol and triglycerides were associated with a decrease in the IMT of common carotid. artery from 0.72+/-0.22 mm to 0.67+/-0.15 mm (p=0.044). In 18 individuals, who were not taking hypolipidaemic drugs, there were no significant changes in the levels of cholesterol and triglycerides and in the IMT of the common carotid artery (increase from 0.58+/-0.18 mm to 0.62+/-0.13 mm, p>0.05). CONCLUSIONS: Lipid-lowering therapy in patients with familial hyperlipidaemia free of symptomatic cardiovascular disease reverses the progression of early, preintrusive atherosclerosis of the carotid artery. It is a beneficial sign indicating the possibility for atherosclerosis regression.

Carotid Artery, Common↗
PubMed1998

[Relation of the thickness of the intima and media of the common carotid artery, atherosclerotic plaque in the carotids and manifestations of atherosclerosis in the vessels of the lower extremity in comparison to coronary atherosclerosis].

BACKGROUND: Concomitant occurrence of carotid atherosclerosis, coronary artery disease (CAD) and peripheral vascular disease (PVD) has been described in a number of studies. The objective of the present trial was to assess the degree of correlation between atherosclerosis of the carotid beds as well as PVD and the extent of CAD. METHODS AND RESULTS: Carotid morphologies of 170 patients in total (121 men, 49 women), ranging between 23 and 81 years in age were assessed ultrasonographically. Their carotid beds searched for plaques, stenoses and occlusions. In all patients intima-media thickness (IMT) of the common carotid artery (CCA) were measured ultrasonographically. In addition, case histories of PVD were taken. CAD was proved angiographically in 138 patients. Plaques in carotid beds were found in 98 patients, carotid artery stenoses > 75% were found in 4 patients whereas complete carotid occlusion was not detected in any patient. Clinically manifested PVD was found in 20 patients. A significant difference in IMT of the CCA was assessed by t-test between patients having and not having CAD (0.67 +/- 0.16 mm vs. 0.87 +/- 0.24 mm; P < 0.0001). The correlation between the IMT of the CCA and extent of CAD was weak (r = 0.30, p < 0.01). A positive correlation between carotid plaque occurrence and the number of CAD-affected arteries was statistically assessed (Trend test: P = 0.0001). The sensitivity of incidence of plaques on the carotid beds for prediction of CAD was 64%, the specificity 72%, the positive predictive value 91% and the negative predictive value 32%. The sensitivity of clinically manifested PVD for prediction of CAD was 15%, the specificity 100%, the positive predictive value 100% and the negative predictive value 21%. CONCLUSIONS: The authors confirmed a statistically significant but weak correlation between IMT of the CCA and severity of CAD. They found a positive trend between the occurrence of carotid plaques and the number of CAD-affected arteries. The presence of carotid plaques and clinically manifested PVD were confirmed as a reliable positive predictive factors for CAD.

Adult↗
PubMed1998

[Treatment of hypopituitarism in adults with growth hormone improves improves the thickness of the arterial intima].

BACKGROUND: Increased mortality of hypopituitary adults with atherosclerotic vascular disease is commonly explained by growth hormone deficiency and forms the main argument for the growth hormone replacement. At the same time it is known that the growth hormone-IGF-I axis stimulates the vessel wall proliferation as an initial step of atherosclerosis. Investigation of the arterial intima thickness in hypopituitary adults with duplex ultrasound system and its follow up during the growth hormone therapy may clarify these effects of growth hormone on the vessel wall. METHODS AND RESULTS: Luminal diameter, maximal blood flow velocity and arterial intima thickness of common carotid arteries was measured with colour duplex ultrasound system in 15 adults with hypopituitarism before and after one year therapy with recombinant growth hormone. The results were compared with healthy controls matched for gender, age, blood pressure and weight. The luminal diameter did not changed during the therapy with growth hormone and was the same in patients and controls. Maximal blood velocity in hypopituitary patients before the therapy was lower than in control subjects (74.8 +/- 13.9 cm/s vs. 94.0 +/- 21.0 cm/s), but the statistical difference was only borderline. Arterial intima thickness was significantly thinner in hypopituitary patients when compared with controls (0.56 +/- 0.1 mm vs. 0.71 +/- 0.12 mm, p < 0.001) but became thicker after the treatment and was not any more different from the controls (0.56 +/- 0.1 mm vs. 0.66 +/- 0.1 mm, p < 0.001). CONCLUSIONS: In hypopituitary adults the arterial intima thickness of common carotid arteries is less than in healthy controls. The reduced thickness was normalised after one year treatment with growth hormone. Atheromatous plaques were not found either before or after the treatment. Duplex ultrasound measurement may be one of the means of checking of the effects of growth hormone therapy.

Adult↗
PubMed1997

[Favorable effect of treatment with statins on the intima of the common carotid artery in patients with familial hyperlipoproteinemia].

BACKGROUND: In recent years evidence was provided that by measuring the width of the intima of the carotid artery, evaluated by sonography, it is possible to assess the development of arteriosclerosis. The authors used this method to evaluate hypolipidaemic treatment. METHODS AND RESULTS: The authors followed-up by clinical and laboratory methods and treated for a period of 47 months 63 patients with familial hyperlipoproteinaemia. At the beginning and at the end of the follow-up period they made sonographic examinations of the common carotid artery. In 31 patients treated by statins they observed statistically significant changes: cholesterol declined by 23%, LDL cholesterol by 25.3%. The maximal rate in the common carotid artery (ACC) declined from 93 +/- 22 to 73 +/- 13 cm/s. The diameters of the ACC increased from 6.0 +/- 0.8 to 6.5 +/- 0.8 mm. The intima of the ACC diminished from 0.84 +/- 0.26 to 0.75 +/- 0.20 mm. In 22 patients treated with fibrates the anticipated lipid changes occurred. The diameter of ACC did not change, the decline in the width of the intima of the ACC was not statistically significant. In 10 patients who decided that they wanted only dietary treatment the changes in the investigated parameters were small. CONCLUSIONS: In patients with familial hyperlipidaemia who were treated with statins for almost four years the authors observed a diminution of the width of the intima of the common carotid artery which is considered a sign of regressing atherosclerosis.

Anticholesteremic Agents↗
PubMed1997

Decreasing common carotid artery intimal thickness during hypolipidemic therapy.

It has been demonstrated in recent years that ultrasound can be used to measure common carotid artery intimal thickness; an increase in intimal thickness is regarded as an early stage of atherosclerosis. This study was designed to establish whether or not intimal thickness can be modulated by therapy. Twenty-nine patients with familial hyperlipoproteinemias had follow-up ultrasound of the common carotid artery after twenty-nine months of comprehensive therapy. In 21 patients with familial hypercholesterolemia, intimal thickness decreased from 0.83 to 0.68 mm (P < 0.01), in 9 with familial combined hyperlipoproteinemia, the decrease was from 0.77 to 0.74 mm (a decrease was seen in only 50% of patients). With the group taken as a whole, the larger decrease was observed in patients treated with statins while the reduction was less marked in those administered fibrates. The authors found a decrease in common carotid artery intimal thickness following hypolipidemic therapy in patients with hyperlipoproteinemias. Their impression is that this was a manifestation of atherosclerosis regression.

Adult↗
PubMed1997

[The effect of 4 years' of hypolipemic treatment on the width of the common carotid artery intima in patients with familial hyperlipidemias].

Sixty-four patients with familial hyperlipoproteinaemia were treated for almost four years by dietetic treatment and various hypolipidaemic drugs. In 25 patients with familial hypercholesterolaemia who had clinical signs of ischaemic heart disease total and LDL-cholesterol declined and the width of the intima of the common carotid artery diminished from 0.78 mm to 0.69 mm (p = 0.004). In the above artery the maximal flow rate of blood declined. The increase was, however, not statistically significant. In 12 patients with familial hypercholesterolaemia who suffered from ischaemic heart disease the width of the intima of the common carotid artery and maximum flow rate did not change, however, the diameter of the artery increased (from 6.3 to 6.6 mm, p = 0.034). In 27 patients with familial combined hyperlipidaemia during the drop of cholesterol, LDL-cholesterol and triacylglycerols the width of the intima of the common carotid artery diminished (from 0.72 to 0.67 mm, p = 0.044), the diameter of the artery increased (from 6.1 to 6.4 mm, p = 0.014). The authors assume that the reduction of the width of the intima during hypolipidaemic treatment reflected the decline of cholesterol in the arterial wall and is a favourable sign which indicates possible regression of atherosclerosis.

Carotid Artery, Common↗
PubMed1995

[Decrease in common carotid artery intimal thickness after hypolipemic therapy].

BACKGROUND: In recent years evidence was provided that it is possible to assess sonographically the thickness of the intima of the common carotid artery, whereby an increase of the thickness of the intima is considered an early stage of atherosclerosis. In the submitted work the authors tried to assess whether it is possible to influence the thickness of the intima by therapy. METHOD AND RESULTS: In 32 patients with familial hyperlipoproteinaemia sonographic control examinations of the common carotid artery were performed after 27 months of comprehensive treatment. In 21 subjects with familial hypercholesterolaemia the thickness of the intima decreased from 0.83 mm to 0.68 mm (p < 0.01), in 8 subjects with familial combined hyperlipoproteinaemia from 0.77 mm to 0.74 mm (a decline was recorded in half the subjects). In the whole group the greatest decrease was recorded in subjects treated with statins and a smaller decrease in those treated with fibrates. CONCLUSIONS: The authors assume that the decrease of the thickness of the intima of the common carotid artery recorded in hyperlipoproteinaemic patients after hypolipidaemic treatment is a manifestation of regression of atherosclerosis.

Adult↗
PubMed1995

[Apoptosis--programmed cell death].

The authors summarize findings on apoptosis-programmed cellular death, incl. basic data on expression of genes promoting (p53, c-myc, MTS 1 and fas) or inhibiting (bcl-2, bcr-abl) this process. The authors discuss clinical possibilities of controlling apoptosis, in particular in oncology and in autoimmune disease, AIDS, metabolic disorders etc.

Apoptosis↗
PubMed1994

[Old age from the viewpoint of the cardiologist].

The general cardiovascular performance of old people is determined by: a) inherent changes of the cardiovascular system which develop with age; b) delay of degenerative changes in some subjects caused by genetic factors, optimal physical activity and a proper diet; c) acquired diseases, in particular arteriosclerosis and hypertension. As a result of degenerative changes of the vascular wall the systolic pressure rises advancing age, some of the old people develop isolated systolic hypertension. Mild hypertrophy of the left ventricle develops also. The contracting ability of the heart muscle is preserved, the ejection fraction at rest and the cardiac output do not change. However, the diastolic function changes significantly-the elasticity of the left ventricle declines and its filling depends more on the atrial systole. A frequent cause of heart failure in old people is diastolic dysfunction. Pharmacotherapy of old people has some specific features which are discussed in more detail. A recent multicentre clinical investigation SHEP proved unequivocally, that effective treatment of systolic hypertension reduced in old people the risk of cerebrovascular attacks by 33%, of acute myocardial infarction by 27% and of cardiac failure by more than 50%! Based on these results it is clear that systolic hypertension must be treated equally systematically as diastolic hypertension. The approach to old people with cardiovascular disease must be strictly individual. Age alone must not be the reason for refusing access to the complete spectrum of modern diagnostic and therapeutic possibilities.

Aged↗
PubMed1993

[Carotid artery and femoral artery disease in asymptomatic patients with various types of hyperlipoproteinemias and in healthy persons].

The authors examined by means of the sonograph Siemens Quantum 2000 the carotid and femoral arteries of 21 controls and 91 asymptomatic subjects with different types of hyperlipoproteinaemia (HLP). 46 patients suffered from familial hypercholesterolaemia, another 19 patients with hypercholesterolaemia suffered from ischaemic heart disease, 21 patients had familial combined hyperlipoproteinaemia and 5 patients had familial dysbetalipoproteinaemia. In the controls no plaques or stenoses were detected. In the different groups with HLP plaques and stenoses on the carotid artery were found in 15-36%, on the femoral artery in 24-63%. In patients with HLP on the common carotid artery in different groups a detectable intima was found more frequently, a statistically highly significantly wider intima (0.73 +/- 0.17 mm to 0.84 +/- 0.31 mm) and a lower maximum rate (79 +/- 18 cm/s to 98 +/- 24 cm/s) than in controls (0.41 +/- 0.14 mm and 121 +/- 30 cm/s resp.). On the common carotid the authors found a significant direct correlation between age and the cholesterol level and between age and the width of the intima and an indirect correlation between age and the maximal rate. The differences in the width of the intima and maximum rate were preserved even when the groups were adjusted for age. Changes of the femoral artery were less marked.

Adult↗
PubMed1993

[The intima of the common carotid artery in patients with hyperlipoproteinemia].

Using sonography, the common carotid artery was examined in patients with hyperlipoproteinaemia and in controls. In 21 controls, the intima was present in 62%, intimal thickness was 0.41 +/- 0.14 mm. In patients with familial hypercholesterolaemia free of ischaemic heart disease (46 patients), the intima was demonstrable in 89%, intimal thickness was 0.74 +/- 0.21 mm. In patients with ischaemic heart disease (19 patients), the intima could be demonstrated in 100%, its thickness was 0.84 +/- 0.31 mm. In 21 patients with familial combined hyperlipoproteinaemia, the intima was present in 90%, intimal thickness was 0.73 +/- 0.17 mm. Intimal thickness was significantly greater (p < 0.001) in all groups of patients with hyperlipoproteinaemia than in the control group. A significant correlation between cholesterol levels and intimal thickness (p < 0.01) was demonstrated.

Adult↗
PubMed1992

[Incidence and changes in mitral regurgitation in balloon valvotomy of the mitral valve. A color Doppler study].

The objective of the work was a detailed examination of the incidence and changes of mitral regurgitation (MR) in conjunction with percutaneous transluminal valvotomy of the mitral valve (VMCH). Using coloured Doppler mapping, the authors examined a total of 40 patients before and in the course of one week after VMCH. They assessed the number of regurgitation jets the site of their development, the timing and haemodynamic impact of MR. Knowing the site of development of MR, the authors were able to assess whether the regurgitation after VMCH persisted, developed de novo or disappeared. The total number of mitral regurgitation increased after VMCH from 38 to 51 (increase by 34%, p < 0.05) with a significant rise of the number of double regurgitation jets (4 before as compared with 12 after VMCH, p < 0.05). Before VMCH the authors recorded a holocystic MR in 53%, after VMCH in 86% of the patients (p < 0.01). While before VMCH almost half the regurgitation jets originated in the central portion of the valve, after VMCH MR originated mainly from the area of commissures (48% regurgitation jets before, 79% after VMCH, p < 0.01). Only in 33% of MR after VMCH persisting regurgitation was involved, almost half (47%) of 38 regurgitation jets present before VMCH, disappeared after valvulotomy. MR displays a considerable variability. This may be one of the reasons why prediction of the development and severity of MR after PTMV is difficult.

Catheterization↗
PubMed1991

The effect of metoprolol on left ventricular systolic and diastolic function in essential hypertension.

Using ultrasound techniques, parameters of left ventricular systolic and diastolic function were assessed in 23 patients with degree I-II essential hypertension treated with metoprolol. Metoprolol administration was followed by increases in ejection fraction (p less than 0.01) and stroke volume (p less than 0.05), a decrease in heart rate (p less than 0.01) while cardiac output remained unchanged. Left ventricular filling was abnormal in 12 patients (52.2%). After metoprolol, the ratio of early diastolic to late diastolic transmitral velocity (E/A) rose; the increase indirectly correlated both with the baseline value of E/A (r = -0.59, p less than 0.01), and the change in heart rate (t = -0.65, p less than 0.01). Improved left ventricular diastolic filling was significant only in patients showing abnormal baseline diastolic function, and may be due to the decrease in heart rate rather than a direct effect exerted by metoprolol on the myocardium.

Adult↗