Biomedical subjects

J Chaloupka

Publications and source records attributed to J Chaloupka.

At least 19 recordsLinked to original sources

PubMed2002

[Obesity--a risk factor].

The nutritional status of a selected population--859 male members of the Fire Rescue Service from 12 districts in the Czech Republic--was assessed in 1997 and 1998. The study provides extensive information on selected anthropometrical and biochemical parameters, especially on those, which are generally used as risk indices for the origin and development of cardiovascular disease (CVD): body mass index (BMI), body fat percentage (b. fat), waist circumference (waist), serum concentrations of total cholesterol (Tchol), HDL- and LDL-cholesterol (HDL-chol, LDL-chol), triacylglyceroles (TAG) and the atherogenic index (AI). As far as lipid parameters were concerned, increased serum levels were estimated in 30.4% (TAG), 54% (Tchol) and 60.9% (LDL-chol) of volunteers. Decreased serum levels of HDL-chol were found in 38.2% of volunteers. An AI higher than 3.5 a.u. was calculated for 79.9% of all subjects in study while an AI higher than 5.0 a.u. was calculated for 45.3% of all subjects. An AI higher than 3.5 a.u. was found in 62% of males with normal weight, in 85% of overweight males and in 92% of obese males. The results of the study proved the considerable prevalence of the overweightness and obesity in the male population group that was followed: according to the calculated BMI, 49.5% of volunteers were estimated to be overweight and 16.3% to be obese. The study concept made it possible to reveal the relationships among the anthropometrical and biochemical parameters followed. The correlation matrix documents a statistically significant dependence among the BMI or waist values and the serum concentrations of Tchol, LDL-chol, TAG and AI. A significant negative correlation was found between the HDL-chol serum concentration and the BMI or waist values. The variance analysis results (the estimated lipid parameter values were divided into groups according to BMI and waist categories) document a statistically significant increase in serum Tchol, LDL-chol, TAG and AI in age categories over 35 years in comparison with the category of men under 25 years of age. For Tchol and LDL-chol a statistically significant increase had already been found in the 25-35 year age category. In comparison with the normal weight category, Tchol serum levels and AI values were statistically significantly higher in both the overweight and obese categories. Statistically significant increase was proven for the TAG and LDL-chol serum levels in both the overweight II. gr. and obese categories. A statistically significant decrease in comparison with the normal weight category was found in the HDL-chol serum levels of both the overweight and obesity categories. In the same way, an increase in Tchol and LDL-chol, TAG serum concentrations and AI values in higher and high risk CVD categories (according to the waist circumference value) was found in comparison with the low CVD risk category.

Adult↗

PubMed2001

Differences in the regulation of the intracellular Ca2+-dependent serine proteinase activity between Bacillus subtilis and B. megaterium.

A rise of the intracellular serine proteinase activity (ISP) during postexponential growth of Bacillus subtilis was decreased by a temperature upshift from 35 degrees to 42 degrees C. However, the amount of both molecular forms of the major intracellular serine proteinase ISP1 determined by immunoblotting was similar at both temperatures or even slightly increased at 42 degrees C. The evolution of the ISP activity in B. megaterium showed an opposite temperature dependence, being faster during growth at 42 degrees C. The amount of immunologically detected ISP1 again did not correlate well with the enzyme activity. Moreover, most of the ISP1 molecules in cell-free extracts from B. megaterium were inactive and were activated by increasing the CaCl2 concentration up to 30 mM--unlike B. subtilis, where the enzymic activity was unaffected by Ca2+ concentration. These data suggest that the ISP1 activity in the two bacillar species during postexponential growth is regulated posttranscriptionally, but that the regulatory mechanisms differ.

Antibodies, Bacterial↗

PubMed2000

Protein catabolism in growing Bacillus megaterium during adaptation to salt stress.

Elevated concentration of NaCl in liquid medium caused a concentration-dependent growth delay (adaptation lag) and decrease in the maximal growth rate of Bacillus megaterium. The adaptation to salt stress was accompanied by transformation of some otherwise stable (long-lived; LLP) cell proteins into quickly degraded (short-lived; SLP) ones. Exposure to the strongly growth-reducing 1 M NaCl increased the size of the SLP 'pool' of intracellular proteins from about 5 to about 15% of total protein. The major intracellular proteolytic capacity of B. megaterium is represented by intracellular serine proteinases (ISP). Paradoxically, their specific activity was lowered or masked during the adaptation phase marked by increased catabolism of short-lived and/or destabilized proteins by the stress. This documents that intracellular proteolytic activity cannot be a key regulator of protein catabolism during adaptation to stress.

Adaptation, Physiological↗

PubMed2000

[Prevalence of obesity in selected subpopulations in the Czech Republic].

The authors present the results of an epidemiological study focused on monitoring selected anthropometric parameters which characterize the nutrition state. 933 volunteers altogether, in age group 19-60 years, were tested in the study. Anthropometric parameters such as weight, height, skinfold thickness and abdomen circumference were measured. BMI and fat tissue percentage were calculated on the basis of gathered data. Overweight was detected in 67.5% of monitored men, obesity in 17.0% of them. Overweight was detected in 50.0% of women, obesity in 18.9% of them. Waist circumference exceeding 102 cm was measured in 41.2% of men and waist circumference exceeding 88 cm in 41.7% of monitored women. The unfavourable nutrition state correlates with a high occurrence of cardiovascular and metabolic diseases appearing within the Czech population.

Adult↗

PubMed1999

Cell viability and protein turnover in nongrowing Bacillus megaterium at sporulation suppressing temperature.

In Bacillus megaterium, a temperature that suppresses sporulation (43 degrees C) only slightly exceeds both the optimum growth temperature and the temperature still permitting sporulation (40-41 degrees C). Here we show that, when cells grown at 35 degrees C and transferred to a sporulation medium, were subjected to shifts between 35 degrees C and the sporulation suppressing temperature (SST, 43 degrees C), their development and proteolytic activities were deeply affected. During the reversible sporulation phase that took place at 35 degrees C for 2-3 h (T2-T3), the cells developed forespores and their protein turnover was characterized by degradation of short-lived proteins and proteins made accessible to the proteolytic attack because of starvation. During the following irreversible sporulation phase refractile heat-resistant spores appeared at T4-T5. Protein turnover rate increased again after T2 and up to T8 60-70% prelabelled proteins were degraded. The SST suppressed sporulation at its beginning; at T3 no asymmetric septa were observed and the amount of heat-resistant spores at T8 was by 4-5 orders lower than at 35 degrees C. However, the cells remained viable and were able to sporulate when transferred to a lower temperature. Protein degradation was increased up to T3 but then its velocity sharply dropped and the amount of degraded protein at T8 corresponded to slightly more than one-half of that found at 35 degrees C. The cytoplasmic proteolytic activity was enhanced but the activity in the membrane fraction was decreased. When a temperature shift to SST was applied at the beginning of the irreversible sporulation phase (T2.5), the sporulation process was impaired. A portion of forespores lyzed, the others were able to complete their development but most spores were not heat-resistant and their coats showed defects. Protein degradation increased again because an effective proteolytic system was developed during the reversible sporulation phase but the amount of degraded protein was slightly lower than at 35 degrees C. A later (T4) shift to SST had no effect on the sporulation process.

Bacillus megaterium↗

PubMed1999

Oxidative stress in microorganisms--I. Microbial vs. higher cells--damage and defenses in relation to cell aging and death.

Oxidative stress in microbial cells shares many similarities with other cell types but it has its specific features which may differ in prokaryotic and eukaryotic cells. We survey here the properties and actions of primary sources of oxidative stress, the role of transition metals in oxidative stress and cell protective machinery of microbial cells, and compare them with analogous features of other cell types. Other features to be compared are the action of Reactive Oxygen Species (ROS) on cell constituents, secondary lipid- or protein-based radicals and other stress products. Repair of oxidative injury by microorganisms and proteolytic removal of irreparable cell constituents are briefly described. Oxidative damage of aerobically growing microbial cells by endogenously formed ROS mostly does not induce changes similar to the aging of multiplying mammalian cells. Rapid growth of bacteria and yeast prevents accumulation of impaired macromolecules which are repaired, diluted or eliminated. During growth some simple fungi, such as yeast or Podospora spp., exhibit aging whose primary cause seems to be fragmentation of the nucleolus or impairment of mitochondrial DNA integrity. Yeast cell aging seems to be accelerated by endogenous oxidative stress. Unlike most growing microbial cells, stationary-phase cells gradually lose their viability because of a continuous oxidative stress, in spite of an increased synthesis of antioxidant enzymes. Unlike in most microorganisms, in plant and animal cells a severe oxidative stress induces a specific programmed death pathway--apoptosis. The scant data on the microbial death mechanisms induced by oxidative stress indicate that in bacteria cell death can result from activation of autolytic enzymes (similarly to the programmed mother-cell death at the end of bacillary sporulation). Yeast and other simple eukaryotes contain components of a proapoptotic pathway which are silent under normal conditions but can be activated by oxidative stress or by manifestation of mammalian death genes, such as bak or bax. Other aspects, such as regulation of oxidative-stress response, role of defense enzymes and their control, acquisition of stress tolerance, stress signaling and its role in stress response, as well as cross-talk between different stress factors, will be the subject of a subsequent review.

Animals↗

PubMed1999

In vivo and In vitro function of the intracellular proteolytic apparatus in nongrowing bacillus megaterium under heat stress

In Bacillus megaterium sporulating at 35 degreesC, up to 90% of 10-min pulse-labeled proteins were degraded. Degradation proceeded in two waves. Short-lived proteins, i.e., intrinsically labile proteins and proteins made short-lived because of starvation, were mostly degraded during the reversible sporulation phase. Their amount corresponded to 20% or slightly more during 2 h. The second wave of protein degradation, which followed during the irreversible sporulation phase at 35 degreesC, increased the amount of total degradable pulse-labeled proteins to about 90%. This wave was absent in the isogenic asporogenic mutant 27-36 or in the wild strain, whose sporulation was inhibited by increased temperature. The proportion of degradable proteins was thus reduced to less than 40% in the asporogenic mutant incubated at 35 degreesC and to 46% in the wild strain whose sporulation was suppressed by the temperature of 47 degreesC. Unlike sporulating cells, these cells were thus capable of degrading short-lived and denatured proteins, but were not able to degrade most of other proteins. The in vitro protein degradation was substantially enhanced by increasing the Ca2+ concentration, suggesting a role of Ca2+-dependent proteinase(s) in the process.

Journal Article↗

PubMed1999

Contrast-enhanced ultrasound for guidance of local tumor ablation.

The objective was to assess the efficacy of sonography with and without contrast medium enhancement in guiding and monitoring percutaneous ethanol ablation of tumors in an animal model. VX-2 carcinoma was implanted into the thighs of New Zealand white rabbits and examined by grey-scale ultrasound, color, power, and pulse Doppler, before and after injection of 95% ethanol into the tumors. Injections of ethanol were guided by ultrasound to sites of tumor vascularity, until all tumor vascularity had been obliterated. Microbubble contrast medium or saline was injected i.v. prior to each of the ultrasonic interrogations. Arteriography was performed before and after ablation. Selected tumor samples were submitted for histologic examination. Contrast enhanced tumor vascularity over saline controls in all cases. In some, incompletely ablated foci of tumor could only be identified with contrast medium enhancement. Arteriography showed complete ablation of all but 1 tumor. We conclude that ultrasound enhanced by contrast better shows the presence or absence of tumor vascularity. Ultrasound enhanced by contrast might offer an accurate means of guiding and monitoring percutaneous ethanol injection for tumor ablation.

Albumins↗

PubMed1998

Occipital lobe vascular malformations: prevalence of visual field deficits and prognosis after therapeutic intervention.

BACKGROUND: The prevalence of visual field (VF) deficits in association with vascular malformations of the occipital lobe is not known, and the prognosis of the VF after therapeutic intervention has not been systematically documented. METHODS: We reviewed the clinical records of 23 consecutive patients who were managed at a single institution during a 3-year period with intracranial vascular malformations extending within the anatomic borders of the occipital lobe. Lesion location and treatment rendered were correlated with formal VF testing performed before and after therapeutic intervention. RESULTS: Twenty-one of the 23 patients underwent treatment of their lesions. Treatment included resection after preoperative embolization (12 patients), resection alone (2 patients with arteriovenous malformations and 3 patients with cavernous malformations), and stereotactic radiosurgery (4 patients; preceded by embolization in 3 of the 4). One patient was followed expectantly, and another died as a result of hemorrhage soon after undergoing endovascular embolization. The VFs were assessed before and after therapeutic intervention (follow-up assessment, 2-29 mo). New VF deficits or worsening of preexisting VF deficits were documented in 5 of the 21 treated patients (24%), but only 2 of these patients (9.5%) had persistent deficits at the time of their follow-up examinations. Among the 10 patients with pretreatment VF deficits, 5 improved and the other 5 were unchanged after treatment. CONCLUSION: Patients with occipital lobe vascular malformations frequently present with associated VF deficits. Surgical resection or stereotactic radiosurgery (with or without previous embolization) of these lesions can be performed with little risk of causing new VF deficits or worsening of preexisting ones. Many VF deficits can be expected to improve or resolve after therapy.

Adult↗

PubMed1998

[Changes in autonomic nervous system activity in obese individuals during weight reduction].

The frequency analysis (fast Fourier transformation) of heart rate variability follow-up during modified orthostatic test is the non-invasive method used to the evaluation of vegetative nervous system (NS) activity. There are only few data about the changes of the parameters in the groups with civilization diseases or with the presence of the risk factors of coronary heart disease. In the groups of 82 volunteers (BMI 24.9 +/- 2.7 kg/m2) and 37 healthy obese people (BMI 36.1 +/- 4.9 kg/m2) we compare some of the vegetative NS parameters. In 16 volunteers we measured the vegetative NS activity changes during the weight reduction regimen (10 day's hospitalization, daily energy intake 3300 kJ, weight before 101.5 +/- 18.1 kg, after 97.5 +/- 17.1 kg, p < 0.0001). Acute reactions to the energy restriction were evaluated in 3 groups of 10 volunteers during 3 days of the energy intake 3200, 6600 and 13400 kJ. Obese persons show a slight decrease of both sympathetic and parasympathetic NS activity. In the supine position only few changes in the sympathetic/parasympathetic NS activity ration were observed. In the standing position in obese group drop of the most indexes and decrease of sympathetic/parasympathetic NS activity ratio were described. Significant correlations between sympathetic NS activity and lipid oxidation (r = 0.329, p < 0.01) as well as saccharide oxidation (r = -0.258, p < 0.05) were observed. During the weight reduction slight increase of the parasympathetic NS activity and higher one in the sympathetic NS activity were measured. The values after weight reduction regime are comparable with the control group of the lean persons. Different changes of the parameters were described in standing and in supine position. Acute reaction on the low-energy diet was observed in a few days. It shows a slight increase of the NS activity parameters. Relative increase mainly in the sympathetic nervous system activity doesn't depend on the degree of energy deficit only, but some subjective factors may play a role (age, psychological and psychosocial factors, agreeability of the diet, behavioral factors ...). In the group of obese persons non-specific changes of the vegetative NS activity were observed. They are modulated by some behavioral factors. The tendency to the higher parasympathetic NS activity confirms the MONA LISA theory of the origin of obesity. Important are the informations of the return of the indexes after overweight reduction.

Autonomic Nervous System↗

PubMed1998

[Non-invasive methods for evaluation of body composition during weight reduction].

As a result of positive energetic balance of organism, there is a cumulation of an excessive energy in the adipose tissue. Adipose tissue repletion represents the main characteristic of obesity. The objective of our work was to perform the comparative study for the evaluation of selected noninvasive methods used for the determination of body composition. We analysed the results of 4 methods of the body composition measurement: bioelectrical impedance (BIA), physical anthropometry (ANTHR), Deurenberg's calculation (FORM) and dual energy X-ray absorptiometry (DEN). The most statistically significant correlation was proved between the results of BIA and results of DEN method (r = 0.9145), and results of BIA and FORM method (r = 0.9014).

Absorptiometry, Photon↗

PubMed1998

Effect of pH on proteinase secretion by transformed fibroblast populations.

Effect of pH on secretion of proteolytic enzymes in cell cultures of three clonal lines of transformed fibroblasts (K2, T15 and K4) was studied by using 14C-labelled denatured proteins as substrate. One line of malignant macrophages derived from mouse reticulum cell sarcoma (J774.1) was used for comparison. The relative motility index of all cell lines was derived by computer analysis of quantitative estimations of cell dispersion in single-cell-derived colonies. Cultivation at pH 6.5 decreased the growth rate in most experiments as compared with that at pH 7.4, and stimulated cell motility to a different extent. The population of mouse malignant macrophages produced several-fold higher extracellular proteolytic activity than the fibroblast lines. Secretion of proteinases by the malignant macrophages was significantly stimulated by the lower pH. Enzyme secretion by two of the three fibroblast derivatives was also stimulated by acidic pH but to a lesser extent than the secretion of the malignant macrophages. The assessment of motility done by measurement of dispersion of cells in colony proved a positive correlation between motility and proteinase secretion in J774.1 cells and one transformed fibroblast clone (T15) but not in the two other clonal lines.

Animals↗

PubMed1998

[Sporicidal effect of Presept and Chloramine B on Bacillus cereus spores].

The sporicidal effect of Presept was compared with Chloramine B on the spores of Bacillus cereus. Either compound was calibrated to the same concentration of active chlorine. While a portion of spore population after 4 hrs of treatment by Chloramine germinated and started to divide in a rich nutrient medium, the optical density of the culture inoculated with spores treated by Presept did not increase even after 7 hrs when exposed to the nutrient medium. Significant morphological differences were found in either population of spores. Spores treated by Presept lost the impermeability within 3 hrs in the nutrient medium but almost no postgerminative development was observed. However, a portion of spores treated by Chloramine B developed after germination within 3 hrs into vegetative cells. It seems that Presept does not block germination and/or loss of impermeability of spores, but prevents their postgerminative development and division.

Bacillus cereus↗

PubMed1996

Computer modeling of cerebral blood flow following internal carotid artery occlusion.

It is difficult to predict the adequacy of the collateral blood flow in patients who undergo internal carotid artery occlusion. In order to address this difficulty, the authors have created a computer model of the cerebral circulation. This model features individualized simulations of the Circle of Willis and its afferent and efferent branches which can predict changes in flow that will occur during internal carotid artery occlusion. Analysis of the flow predictions suggests that in patients with a symmetric Circle of Willis the anterior communicating artery is the major conduit of collateral blood supply. In patients with a small anterior communicating artery, the posterior communicating arteries become more important as sources of collateral flow, but they cannot supply as much flow as in the case of a normal anterior communicating artery. Sensitivity studies show that changes in the dimensions of each artery affect the flow throughout the system, such that the arteries in the cerebral circulation must be analyzed as a network rather than as isolated elements. This computer model of the cerebral circulation may help clinicians predict the adequacy of collateral blood supply in patients who undergo internal carotid artery occlusion.

Carotid Arteries↗

PubMed1996

Asporogenic Bacillus megaterium mutant 27-36 degrades intrinsically short-lived proteins but fails to convert most of other proteins to a short-lived fraction.

Asporogenic mutant blocked in the 0-II sporulation stage degraded pulse-labelled proteins in the sporulation medium at the same rate as the parental strain for the first two hours. The degraded fraction was mostly composed of intrinsically short-lived proteins which were degraded even after enriching the medium with amino acids and growth resumption. Proteins accessible to degradation because of nutritional shift down formed a lesser proportion of this fraction. The acceleration of protein turnover in the parent strain during the irreversible sporulation phase was not developed in the mutant. A first order kinetic model of protein degradation was used for parameter estimation. Ca(2+)-dependent intracellular serine proteinase was synthesized in an inactive form, which was activated by increasing Ca2+ concentration to 30 mM.

Bacillus megaterium↗

PubMed1995

[Proteolytic enzymes in cell physiology and pathophysiology].

Extracellular proteases (proteinases, endopeptidases) are usually synthesized as larger precursors containing a signal sequence in the N-terminal part of their molecule. The signal sequence contains a sequence composed of hydrophobic amino acids which facilitate the transport of the polypeptide through membranes of the secretory apparatus. Extracellular proteinases play an important role in reproduction and spreading of tumor cells and in tissue remodelling in addition to their function in digestion food proteins. Intracellular proteinases are mostly localized in the cytoplasm and in specialized organelles (lysosomes) but are present also in nuclei and in mitochondria. They degrade or modify cell proteins and are thus involved in protein turnover which is necessary for cell viability. Intracellular proteinases are important components of the cell defense system which protects the cell against the effect of different stress factors by removing damaged and nonfunctional proteins. They modify different proteins and are thus involved in virus reproduction because some proteins are synthesized as nonfunctional virus precursors. Intracellular proteinases also play a role in the cell cycle control and in cytodifferentiation. Rather complex proteolytic enzymes were found even in very primitive organisms (archebacteria).

Animals↗

PubMed1995

Intracellular serine proteinase behaves as a heat-stress protein in nongrowing but as a cold-stress protein in growing populations of Bacillus megaterium.

A temperature increase from 35 degrees to 40-42 degrees C enhances the rise of cytoplasmic serine proteinase (ISP1) activity in Bacillus megaterium incubated in a sporulation medium. A temperature shift from 27 degrees C in the growth medium to 35 degrees C in the sporulation medium has the same effect. Elevated temperature stimulates the increase of ISP1 level when applied immediately after the transfer of cells from the growth to the sporulation medium (at T0) or at T3, when sporulation becomes irreversible. The cytoplasmic PMSF-resistant activity or the proteolytic activity associated with the membrane fraction is stimulated only slightly or not at all. A temperature increase to 45-47 degrees C suppresses the rise of proteolytic activities in all cell fractions. In addition to the elevation of the ISP1 activity by an upward temperature shift, the rise of this enzyme in nongrowing cells is also stimulated by osmotic stress. In growing populations, in contrast to the rise of the ISP1 activity caused by elevated temperature in nongrowing cells, this proteinase is induced by low temperatures (24-27 degrees C). The ISP1 activity roughly correlates with the enzyme protein concentration determined by immunoblotting.

Bacillus megaterium↗

PubMed1994

Heat and osmotic stress enhance the development of cytoplasmic serine proteinase activity in sporulating Bacillus megaterium.

The intracellular Ca(2+)-dependent serine proteinase (ISP1) activity in the cytoplasm of nongrowing Bacillus megaterium incubated in a sporulation medium was determined at 35 degrees C and at temperatures decreasing the sporulation frequency (42 degrees C) or suppressing sporulation (43.5 degrees C). The enzyme in the crude cytoplasmic fraction was partially inhibited by a loosely bound inhibitor(s) because the ISP1 activity rose after protein fractionation by HPLC. Temperature shift-up or osmotic stress applied at 35 degrees C increased the development of the ISP1 activity several times. The increase was caused at least partially by the synthesis of the enzyme protein, as proved by SDS-PAGE and immunoblotting of the cytoplasm. This enzyme thus probably belongs among heat-shock proteins.

Bacillus megaterium↗