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M Karasek

Publications and source records attributed to M Karasek.

At least 19 recordsLinked to original sources
PubMed2006

Primary stenting in the treatment of focal atherosclerotic abdominal aortic stenoses.

AIM: To evaluate the results of primary stent placement in focal atherosclerotic aortic stenoses using balloon expandable stents. MATERIALS AND METHODS: Twenty-six primary balloon expandable stent placements in the abdominal aorta were performed and reviewed. All the aortic stenoses were atherosclerotic. Patients were followed up by ankle/brachial pressure indices (ABPI) and Doppler ultrasound (US) at 24h after procedure and at 12 and 24 months. Follow-up angiograms were performed at 12 months. RESULTS: Twenty-six stents in 26 patients were placed in the infrarenal aorta. All procedures were technically successful and immediate clinical success was obtained. The mean ABPI significantly improved from 0.52+/-0.10 to 0.94+/-0.09 within 24h after procedure, and remained at 0.90+/-0.12 between 12 and 24 months follow-up (mean 18 months). There was full haemodynamic success at hospital discharge and at 12 and 24 months after the procedure. Clinical success at 12 and 24 months (mean 18 months) was defined as an improvement in the Fontaine classification by at least one class compared with the pre-procedure class and was shown to be 100%. CONCLUSION: In summary, we report that primary stenting is a safe and effective alternative to surgery in cases of symptomatic stenosis of the infrarenal abdominal aorta. The excellent intermediate term results suggested that we would recommend primary stenting as the treatment of choice for focal atherosclerotic stenoses of the infrarenal aorta in selected patients.

Adult↗
PubMed2006

Melatonin in humans.

Melatonin, the hormone of the pineal gland, received a great deal of attention in the last decade because of its availability as over-the-counter drug or food supplement in some countries and suggested role in many vital physiological processes. Melatonin secretion is not restricted to mammals but is also produced in nonmammalian vertebrates, in some invertebrates, and in many plants, with the same molecular structure. The synthesis of melatonin is strictly controlled by lighting conditions and shows a clear circadian rhythm with low values during the daytime and significant increase at night. In this survey the basic data on melatonin significance in human physiology and in pathological processes as well as its possible therapeutic significance are reviewed and discussed.

Humans↗
PubMed2001

Melatonin and RZR/ROR receptor ligand CGP 52608 induce apoptosis in the murine colonic cancer.

The effects of melatonin and the thiazolinidinedione derivative CGP 52608 on apoptosis of Colon 38 cancer cells were investigated. Male mice were implanted subcutaneously with a suspension of Colon 38 cells. Ten days after induction of tumors, the animals were treated with melatonin or CGP 52608. Both substances were given in subcutaneous injections in daily doses of 10 or 100 microg in the evening for 6 days. The control group received solvent. The apoptotic cells were visualized in paraffin sections by means of the transferase-mediated dUTPnick end-labeling method. Both treatments increased significantly and to the same degree the number of apoptotic cells in tumors. This finding confirms our earlier observation that melatonin exerts a pro-apoptotic effect on murine colonic cancer cells. Moreover, because CGP 52608 is a ligand of RZR/ROR receptors and the latter are considered by some investigators as nuclear binding sites for melatonin, our data suggest the involvement of these receptors in the pro-apoptotic effect of melatonin.

Animals↗
PubMed2001

Diurnal profile of melatonin concentrations in patients with major depression: relationship to the clinical manifestation and antidepressant treatment.

OBJECTIVES: The aim of the study was to establish if there are differences in the 24-hour melatonin secretion profile between patients with major depression (before, and after treatment with clomipramine) compared to those in healthy subjects. Additionally, we determined if there are differences in melatonin concentrations, depending on the severity of depression, and the presence of 24-hour rhythm disturbances. MATERIAL AND METHODS: Twenty patients with major depression and 24-hour rhythm disturbances, and 14 healthy volunteers took part in the study. Before, and after treatment with clomipramine all subjects had blood samples collected at 08:00, 14:00, 20:00, 24:00, 02:00, 04:00, and 08:00 h, for estimation of melatonin concentrations. Before and after treatment, the severity of depression was evaluated using the following scales: the Hamilton Depression Rating Scale (HADRS), Beck Depression Inventory (BDI), and clinical observation, as well as presence, and if so, severity of 24-hour rhythm disturbances were assessed. RESULTS: In individuals with major depression with marked disturbances of their diurnal rhythms, melatonin secretion is also disturbed, shown by the higher melatonin concentrations at night as compared to those in healthy individuals. However, melatonin levels were independent of the severity or the clinical manifestation of depression. Moreover, no correlation between the disturbances in their diurnal rhythms (sleep-watchfulness, diurnal mood shifts) and disturbed melatonin pattern was observed. CONCLUSIONS: Melatonin nocturnal concentrations in patients with major depression were higher than those in healthy individuals. However, the melatonin concentration values do not differentiate the patients in terms of the severity of the depressive symptoms.

Adult↗
PubMed2000

Twelve-month follow-up of a controlled trial of intradiscal thermal anuloplasty for back pain due to internal disc disruption.

STUDY DESIGN: Case-control study. OBJECTIVES: To determine the prima facie efficacy of intradiscal electrothermal anuloplasty (IDTA). SUMMARY OF BACKGROUND DATA: Although it is being used increasingly as a putative treatment for internal disc disruption, no studies have been published on the efficacy of IDTA. METHODS: Fifty-three patients with back pain determined by computed tomographic (CT)-discography to be due to internal disc disruption were offered treatment. The outcomes of 35 patients treated with IDTA were compared with those of a convenience sample of 17 patients treated with a physical rehabilitation program, by using a visual analog pain scale, use of analgesics, and return to work as measures. RESULTS: At 3 months, only one control patient obtained any significant degree of relief of pain, compared with 23 in the index group. Relief of pain was sustained at 6 and 12 months and was associated with improvement in disability, reduced drug use, and a return to work rate of 53%. Depending on the stringency of criteria used, the success rate of IDTA may be as low as 23% or as high as 60% with confidence intervals of +/-16%. CONCLUSIONS: In carefully selected cases, IDTA can eliminate or dramatically reduce the pain of internal disc disruption in a substantial proportion of patients and appears to be superior to conventional conservative care for internal disc disruption.

Adult↗
PubMed2000

Divergent effects of extracellular oxygen on the growth, morphology, and function of human skin microvascular endothelial cells.

Partial pressure of extracellular oxygen influences a number of major cellular functions. The purpose of this study was to determine if the proliferation, morphology, and synthesis of proteins important in the function of skin microvascular endothelial cells were significantly altered by an extracellular oxygen tension used to culture endothelial cells. Microvascular endothelial cells were isolated from the dermis of neonatal foreskins and were studied at a venous capillary oxygen level (5% O(2), 38 mm Hg) and at an atmospheric oxygen level (20.8% O(2,) 158 mm Hg). At all time points studied and at all passage numbers, a significant inhibition of proliferation was observed at 20.8% O(2) compared to identical cultures grown and subcultured at 5% O(2). Two morphologically distinct endothelial cell populations were observed at 5% O(2). When mediators of angiogenesis and inflammation-such as basic fibroblast growth factor (bFGF), phorbol myristate acetate (PMA), and interleukin-1beta (IL-1beta)-were studied, additional differences in proliferation were observed. Atmospheric O(2) inhibited the synthesis of a major basement membrane protein (Type IV collagen), a major surface protein (PECAM-1), and increased the synthesis of von Willebrand factor (vWf). The rate of vascular channel formation induced by collagen gels was decreased at 5% O(2). These results demonstrate that an increase in extracellular oxygen tension from 5 to 20.8% can significantly alter the cellular physiology of human skin microvascular endothelial cells.

Atmospheric Pressure↗
PubMed2000

Serial transplants of DMBA-induced mammary tumors in fischer rats as model system for human breast cancer: V. Myoepithelial-mesenchymal conversion during passaging as possible cause for modulation of pineal-tumor interaction.

An elevation of melatonin secretion parallel to an enhanced production of macrophage-derived biopterin was observed in female F344 Fischer rats bearing passage 2 serial transplants derived from a malignant mammary tumor induced by 7,12-dimethylbenz[a]anthracene (DMBA). As opposed to that both parameters were depressed at passage 12. These results indicate the presence of divergent immunoneuroendocrine interactions during different phases of tumor growth. Since these biochemical events must have their common origin in changes taking place within these tumor transplants the current histopathological study was initiated. The primary tumor used for serial transplantation was a moderately differentiated adenocarcinoma of the mammary gland showing cytokeratin-positive epithelial components located in the inner epithelial tubule layer. In addition, bland-looking round or elongated actin-positive myoepithelial cells were detected which apart from epithelial cells are known to constitute the main cellular components of the mammary ductal system which resemble smooth muscle cells both morphologically and functionally. The tumor of passage 1 showed glandular tubules, lined by an inner epithelial layer, and many nests of clear, bland-looking actin-positive myoepithelial cells lying around tubules as well as in the stroma between actin-negative epithelial elements. The tumor of passage 2 used for transplantation consisted of a chaotic mixture of epithelial carcinomatous cells, forming a few irregular small tubules or solid nests, and, predominantly, of elongated plump or spindle-shaped, "myoid" atypical myoepithelial cells with a strong actin-positive reaction and some of these cells showed a focal vimentin expression. The tumor was characterized as a carcinosarcoma. At passage 12 epithelial cells were not identified. The tumor displayed features of a pleomorphic sarcoma consisting mainly of giant cells with bizarre nuclei being cytokeratin- and desmin-negative, weakly vimentin-positive but strongly actin-positive. These results indicate that DMBA-induced mammary tumor cells in female F344 Fischer rats undergo dramatic morphological changes during serial transplantation characterized by a total loss of malignant epithelial (carcinomatous) cells and the emergence and subsequent predominance of malignant (sarcomatous) mesenchymal cells. It appears that these sarcomatous cells develop out of myoepithelial cells since atypical myoepithelial cells with a strong actin-positive reaction showed a focal vimentin expression at passage 2 indicating myofibroblastic differentiation as part of mesenchymal transition. The loss of epithelial cell elements as well as a parallel transition of myoepithelial to mesenchymal cell elements during passaging could lead to a lack of immunological recognition of these tumor transplants and to depression of melatonin. Possible mechanisms involved in these phenomena as well as the relevance of these findings for a better understanding of the role of melatonin in human mammary cancer are discussed.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2000

In vitro characteristics of neonatal hemangioma endothelial cells: similarities and differences between normal neonatal and fetal endothelial cells.

BACKGROUND: Increased angiogenesis and eventual involution are major characteristics of neonatal hemangiomas. The mechanism to explain this transition is not completely understood. METHODS: To determine the nature of these changes, endothelial cells were isolated from eight hemangiomas and the growth characteristics and morphology of these cells were compared to cells isolated from normal fetal and neonatal skin. Three cells lines were further characterized by analyzing protein expression with immunohistochemistry and FACS analysis. RESULTS: Hemangioma endothelial cells converted to a spindle-shaped morphology similar to that of fetal endothelial cells whereas neonatal endothelial cells maintained their characteristic epithelioid morphology. While neonatal, hemangioma and fetal endothelial cells continued to express platelet-endothelial cell adhesion molecule-1 (PECAM-1) and von Willebrand factor (vWf), hemangioma and fetal cells expressed both proteins at a lower level and in a distribution distinct from normal neonatal endothelial cells. Neonatal endothelial cells continued to express epithelial specific Type IV collagen, while hemangioma and fetal endothelial cells produced interstitial Type I collagen. CONCLUSIONS: Both cell morphology and protein expression of neonatal hemangioma endothelial cells were more characteristic of embryonic microvascular endothelial cells than that of postembryonic cells demonstrating a similarity in these two cell types and suggesting a dysfunction in the normal growth and maturation of endothelial cells in this tumor.

Biomarkers, Tumor↗
PubMed2000

Chronic exposure to 25-80-microT, 200-Hz magnetic field does not influence serum melatonin concentrations in patients with low back pain.

There is substantial evidence that magnetic field (MF) exposure influences melatonin secretion in animals. However, data on its influence on human melatonin levels are scarce, and seemingly contradictory. Because of its many beneficial effects, very low-frequency MF exposure is used in physiotherapy of some neurological diseases and overloading syndromes of the locomotor system. In previous studies, we observed a decrease in human serum melatonin nocturnal concentrations after exposure to MF (2.9 mT, 40 Hz), and we suggested that differences among various studies may depend on different characteristics of the applied MF. Therefore, in the present study, we examined whether or not MF of different parameters exerts the same effect. The study was performed in seven men (mean age: 36.7 +/- 3.8 years; range: 32-42) suffering from low back pain. Patients were exposed to a pulsating MF (induction: 25 80 microT; frequency: 200 Hz, modulated, automatically programmed; complex saw-like impulse shape; bipolar) generated by a Quatronic MRS 2000 apparatus ("magnetic bed") for 3 wk (5 days/wk, twice a day at 08:00 and 13:00 hr for 8 min each), applied to the whole body in patients laying in a horizontal position. The study was performed in spring. Diurnal serum melatonin profiles were estimated 1 day before exposure to MF (baseline), and 1 day and 1 month after the last exposure. No changes in melatonin concentrations were observed either after 1 day or after 1 month following the exposure in comparison to baseline.

Adult↗
PubMed1998

Chronic exposure to 2.9 mT, 40 Hz magnetic field reduces melatonin concentrations in humans.

Diurnal rhythm of serum melatonin concentrations was estimated in 12 men with low back pain syndrome before and after exposure to a very low-frequency magnetic field (2.9 mT, 40 Hz, square wave, bipolar). Patients were exposed to the magnetic field for 3 weeks (20 min per day, 5 days per week) either in the morning (at 10:00 hr) or in the late afternoon (at 18:00 hr). Significant depression in nocturnal melatonin rise was observed regardless of the time of exposure. This phenomenon was characteristic for all the subjects, although the percent of inhibition of melatonin secretion varied among the studied individuals.

Adult↗
PubMed1997

[Complications after percutaneous biliary drainage and their clinical significance].

Percutaneous Biliary Drainage (PBD) is a simple, relatively painless and inexpensive palliative procedure, performed in cholestatic jaundice caused by non-operative neoplastic tumor of main biliary ducts (Klatskin's tumor). 60 cases of PBD were presented with special remarks concerning early and late complications. Proper technique preventing complications as well as schematic approach in late complications were described.

Bile Duct Neoplasms↗
PubMed1997

[Surgical complications after renal percutaneous transluminal angioplasty].

In this article complications, occurred after 120 procedures of renal PTA, have been analyzed. Serious complications occurred in 7% of patients and required surgical operation. Reduction of amount of complications depends on settlement of adequate indications to PTA and experience of surgeons, making this procedures.

Adult↗
PubMed1994

The response of human dermal microvascular endothelial cells to hypoxia.

Dermal microvascular endothelial cells (DMEC) exposed to hypoxic conditions show a rapid induction of several proteins that do not increase in other cell types placed in a similar environment. These DMEC proteins differ from the well-characterized stress proteins that have been observed in a wide variety of cultured cell types. The DMEC proteins are induced rapidly, within 2-4 h, and are expressed transiently. They include a group of acidic proteins (pI approximately 5-5.2) with molecular weights in the range 100,000-120,000 and at least one glycoprotein (pI 5.1, M(r) 57,000) that is probably expressed on the cell surface. In some primary DMEC cell strains, this response is accompanied by a transient overall increase in protein synthesis. The oxygen-regulated proteins (ORP) that are induced in most other cell types under hypoxic conditions show little variation in their rate of synthesis in DMEC within the first 24 h. The response of DMEC differs from that of umbilical vein endothelial cells (UVEC) and from spindle-shaped cells derived from DMEC, that show a response to hypoxia that is similar to most other cell types. The changes seen in DMEC proteins take place in the same time scale as ischemia-reperfusion injury and may reflect the specialized change of functions of the microvasculature observed under conditions of hypoxic stress in vivo.

Cell Hypoxia↗
PubMed1994

Effects of p-chlorophenylalanine, amiflamine and melatonin treatment on the ultrastructure of pinealocytes in Sus scrofa.

The effects of p-chlorophenylalanine (pCPA), amiflamine [Fla 336(+)] as well as melatonin (MEL) treatments on the ultrastructure of pinealocytes in immature female pigs were investigated. Treatment of pCPA-tryptophan hydroxylase inhibitor resulted in the presence of numerous membrane-bound bodies type 2, with long, narrow cisterns of endoplasmic reticulum and a large Golgi apparatus. Fla 336(+) selective MAO-A inhibitor influenced the system of dense bodies, mitochondria and lysosomes (increasing their relative volume). Injections of melatonin resulted in the appearance of numerous homogeneous, round, regular shaped structures surrounded by membrane cytoplasmic structures ('granules'). The results indicate that a peculiar system of cytoplasmic dense bodies may be involved in indoleamine secretion in the pig pinealocyte.

Animals↗
PubMed1993

Day-night changes in the ultrastructure of pinealocytes in the Syrian hamster: a quantitative study.

The ultrastructure of pinealocytes was studied in Syrian hamsters maintained under 12:12 light: dark cycle, both during the daytime (1300h) and at night (0100h). At night the pinealocytes showed ultrastructural features indicating an increased metabolic and synthetic activity of these cells. It was expressed by higher relative volumes of mitochondria, lysosomes, lipid droplets, granular endoplasmic reticulum and vacuoles containing flocculent material at night in comparison with those during the daytime. By contrast, the number of the dense-core vesicles, both in the cell body and in the endings of pinealocyte processes was higher during the daytime than at night. Quantitative morphological results correlate with the well known nocturnal enhancement in biochemical activity of the pineal gland, especially the circadian rhythm of the secretion of the pineal hormone-melatonin.

Animals↗