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Biomedical subjects

R Kowalewski

Publications and source records attributed to R Kowalewski.

At least 19 recordsLinked to original sources
PubMed2004

Matrix metalloproteinases in the vein wall.

AIM: Matrix metalloproteinases contribute to extracellular matrix remodelling that can influence mechanical properties of the vein wall and predispose to varicose veins development. The aim of the study was to assess the following matrix metalloproteinases in the wall of varicose veins: tissue collagenase I (MMP-1), gelatinase A (MMP-2), gelatinase B (MMP-9) and stromelysin 1 (MMP-3). METHODS: Normal, varicose and varicose veins complicated by thrombophlebitis were collected during the surgical treatment of 26 patients. In harvested tissues the presence of gelatinases was detected with zymography, contents of MMP-1, MMP-2, MMP-3 and MMP-9 were evaluated with ELISA, activity of MMP-1 was assessed with HPLC and activity of MMP-2 with ELISA. RESULTS: Zymography demonstrated particularly high contents of both gelatinases in the wall of varicose veins complicated by thrombophlebitis. The contents of MMP-1, MMP-2 and MMP-9 were significantly increased only in the wall of varicose veins complicated by thrombophlebitis, whereas the increased content of MMP-3 was also found in the wall of varicose veins. A significantly higher activity of MMP-1 was shown only in the wall of varicose veins complicated by thrombophlebitis, whereas an active form of MMP-2 was increased in the wall of varicose, as well as varicose veins complicated by thrombophlebitis, when compared with normal ones. CONCLUSION: The wall of varicose veins, particularly those complicated by thrombophlebitis shows extensive alterations in the content and activity of matrix metalloproteinases, that may result in extracellular matrix remodelling, influence mechanical properties of the vein wall and predispose to further progression of the disease.

Chromatography, High Pressure Liquid↗
PubMed2004

Chemical compound content and enzyme activity in supernatant and sediment of liver homogenate.

Evaluation was performed of chemical compound contents and enzyme activities in the whole homogenate, its supernatant and sediment. Six rabbit livers were pulverized in liquid nitrogen and homogenized. After centrifugation, the contents of protein, haemoglobin, vitamin A, vitamin E, vitamin C, as well as the activities of cathepsin B, cathepsin D, superoxide dismutase, catalase, glutathione peroxidase and reductase were assessed in the whole homogenate, its supernatant and sediment. Protein, vitamin A, superoxide dismutase, catalase, cathepsin D, glutathione peroxidase and reductase reveal uniform localisation. Vitamin C and cathepsin B are localized in supernatant, whereas haemoglobin is localized mainly in sediment. Evaluation of chemical compounds and enzyme activities should be performed in the whole homogenate, supernatant and sediment to obtain a real interpretation of biochemical disturbances in the investigated material.

Animals↗
PubMed2004

Assessment of connective tissue fibres in walls of allogenic arterial grafts preserved by the method of cold ischemia--a preliminary report.

The aim of the study was to evaluate microscopic changes in the wall structures of allogenic arterial grafts, preserved by the method of cold ischemia in relation to the storage period and to test the possibility of the storage period prolongation by allograft freezing at -70 degrees C. The middle layer ultrastructure is well preserved till 30 days from allograft harvesting, however, allograft freezing results in total destruction of elastic and collagen fibres in the arterial wall. An application of allogenic arterial grafts, preserved by the method of cold ischemia till 30 days from their harvesting, seems an efficient therapeutic method in the treatment of patients with synthetic vascular graft infection. Further prolongation of the storage period at -70 degrees C made the allograft useless for implantation.

Aorta, Abdominal↗
PubMed2004

Some components of oxidative-antioxidative system in human blood plasma and serum.

Comparison of the concentrations and activities of components in the oxidative-antioxidative system between blood plasma and serum. Blood plasma and serum samples were obtained from 38 healthy adults to evaluate malondialdehyde concentration, the total antioxidative capacity, superoxide dismutase activity, protein and non-protein sulphydryl groups, ascorbate, haemoglobin, methaemoglobin and protein. Blood plasma shows higher activity of superoxide dismutase, as well as higher concentrations of low-molecular sulphydryl groups and ascorbate, when compared to those in blood serum. The total plasma antioxidative capacity is also higher than that assessed in blood serum. Processes of blood coagulation and blood clot retraction lead to antioxidant consumption. The evaluation of oxidative-antioxidative system for diagnostic purposes should be performed in blood plasma.

Adult↗
PubMed2004

Haemoglobin of varicose vein, varicose vein with thrombophlebitis and in parietal thrombus of varicose vein.

Saphenous veins were taken for examination: unchanged, varicose with thrombophlebitis and varicose thrombus. The contents of haemoglobin and protein were determined in the homogenate of that material. Only small quantities of haemoglobin were found in walls of unchanged veins. Greater amounts of haemoglobin were observed in walls of varicose veins, especially in walls of varicose veins with thrombophlebitis. The varicose vein thrombus also contained marked quantities of haemoglobin.

Chromatography, Gel↗
PubMed2001

Glycosaminoglycans of normal veins and their alterations in varicose veins and varicose veins complicated by thrombophlebitis.

The aim of the study was to examine the content and molecular differentiation of glycosaminoglycans (GAGs) in the wall of varicose veins. The studied material consisted of normal, varicose veins and varicose veins complicated by thrombophlebitis collected during operations on 26 patients. In the wall of varicose veins the mean GAGs' content as well as the content of sulphated GAGs, except heparan sulphate was increased, whereas the amount of hyaluronic acid was decreased. Furthermore, the increased quantitative ratio between sulphated and nonsulphated GAGs was demonstrated. The results indicate an evident extracellular matrix remodelling in the wall of varicose veins particularly those complicated by thrombophlebitis, that is characterised by alterations in the content and molecular differentiation of GAGs.

Adult↗
PubMed2000

Effects of changing stance conditions on anticipatory postural adjustment and reaction time to voluntary arm movement in humans.

1. The effect on reaction time (RT) and anticipatory postural adjustment (APA) of unexpectedly changing stance conditions was studied using a push or pull arm movement task. The aim was to evaluate the modifiability of RT and APA by an external perturbation associated with an automatic compensatory reaction. 2. Subjects standing on a moveable platform were asked to push or pull a rigid handle as quickly and as strongly as possible in response to the 'go-signal', a visual signal from a green or red light-emitting diode. Forward and backward translations of the platform were randomly induced at four time intervals after the go-signal. In some experiments to detect unspecific arousal there were no platform translations but an acoustic signal was given before the go-signal. Surface electromyographic activity (EMG) of upper arm and lower leg muscles was analysed. 3. During the push task both RT and the duration of APA (onset of APA till the force signal indicating hand action) were shorter during backward than during forward translation. During the pull task the effect of platform translations was the reverse. The delay between go-signal and onset of APA remained constant. Consequently, RT and APA became shorter when the platform was translated in the same direction as that in which the upper body was displaced by the push or pull movement, and longer when it was translated in the opposite direction. The effects were maximal when translations were induced 250 ms after the go-signal, but a difference was detected up to 375 ms. 4. Furthermore, with forward and backward platform translations RT was shorter when the translations were induced early rather than late after the go-signal. This was associated with a shortening of the delay between the go-signal and onset of APA, while APA duration remained constant. The shortened RT was in the range of that obtained when an acoustic signal was given just before the go-signal. 5. It is concluded that (i) both the RT and the duration of APA can be modified by a translation of the support surface in a functionally appropriate way by updating the internal representation of the actual stance condition within the central nervous system. Both RT and APA are shortened when the body displacement induced by the push or pull movement and platform translation have the same direction; conversely, an inappropriate translation of the feet requires a greater APA and leads to a longer RT; (ii) both APA and RT are modifiable by platform translation for more than half the time between the go-signal and the focal push or pull movement; (iii) an unspecific effect of platform translation on RT can be identified; it may be mediated by a different neuronal substrate.

Adult↗
PubMed1999

Heterogeneous characteristics of imidazoline-induced insulin secretion.

Imidazolines are regarded as a pharmacological group of insulin secretagogues with one uniform mechanism of action, namely closure of ATP-dependent K+ channels (K(ATP) channels) and, in consequence, depolarization of the plasma membrane, Ca2+ influx and stimulation of secretion. This assumption was investigated by measuring insulin secretion from perifused pancreatic islets in response to three imidazoline compounds and comparing the characteristics of secretion with changes in membrane potential and cytosolic Ca2+ concentration [Ca2+]i of single beta-cells. Phentolamine (32 microM) stimulated insulin secretion from perifused mouse islets in the presence of stimulatory (10 mM and 30 mM) and substimulatory (5 mM) glucose concentrations and even in the absence of glucose. Idazoxan in concentrations up to 500 microM was virtually ineffective in the presence of 5 mM glucose. At 10 mM glucose, there was a moderate but significant increase of secretion by idazoxan, 20 microM being nearly as effective as 100 microM. The effect of phentolamine was of slow onset and irreversible in the time frame of the experiments, while the effect of idazoxan was of fast onset and reversible. Alinidine also stimulated secretion in the presence of 10 mM glucose with fast and reversible kinetics, but in contrast to idazoxan, 100 microM was clearly more effective than 20 microM. These heterogeneous characteristics of secretion were reflected by changes of [Ca2+]i: the increase of [Ca2+]i by phentolamine was slow and only partially reversible, whereas idazoxan led to a smaller, but faster and reversible response. The increase of [Ca2+]i by phentolamine and idazoxan was abolished by the Ca2+ channel blocker D 600. Surprisingly, all three compounds depolarized the beta-cell plasma membrane from a resting potential of -71 mV to about -36 mV. Again, the effect of phentolamine was slow and that of idazoxan and alinidine fast. Thus, the characteristics of phentolamine-induced secretion appear to be attributable to the consequences of K(ATP) channel closure. It is unclear, however, why all three test compounds achieved the same degree of depolarization in spite of their known different efficiency to close K(ATP) channels. Apparently, there are additional mechanisms involved in the action of idazoxan and alinidine, which may contribute to the obvious differences in the characteristics of secretion.

Adrenergic alpha-Antagonists↗
PubMed1997

Somatosensory evoked potential monitoring during cardiac surgery: an examination of brachial plexus dysfunction.

OBJECTIVE: To observe the effects of the Favoloro and sternal retractors on the ulnar and median nerve somatosensory evoked potentials (SSEPs) and to identify any relationship with postoperative brachial plexus injury. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Twenty cardiac patients. INTERVENTIONS: SSEPs were studied in patients undergoing cardiac surgery using normothermic cardiopulmonary bypass. Evoked potentials were obtained from bilateral median and ulnar nerves. MEASUREMENTS: The incidence of nerve-specific SSEP changes and their temporal relationship to retractor usage were determined. The overall incidence of SSEP changes was 75%. There were no differences (p > 0.05) between the group showing changes (n = 15) and the group with no changes (n = 5) with respect to age, body surface area, weight, cross-clamp or cardiopulmonary bypass times. There also were no differences (p > 0.05) between the frequencies of left- and right-sided changes, or in nerve-specific SSEP changes. Seventy-four percent of SSEP changes correlated with retractor usage. No SSEP changes were associated with the Favoloro retractor. Significant SSEP depression, assessed by either percentage reduction in amplitude or persistent amplitude reduction, occurred in the absence of postoperative neurological deficits. There were no detected postoperative brachial plexus injuries. CONCLUSIONS: SSEP changes correlate with the use of the sternal retractor but not the Favoloro retractor. It was not possible to replicate the results of previous investigators in predicting postoperative neurological deficits based on the SSEP changes, and therefore the routine application of SSEP as a monitor cannot be recommended on the basis on these data.

Aged↗
PubMed1995

Effects of imidazoline compounds on cytoplasmic Ca2+ concentration and ATP-sensitive K+ channels in pancreatic B-cells.

Phentolamine, an alpha-adrenoceptor-blocking agent with an imidazoline structure, induces an increase in the cytoplasmic Ca2+ concentration of pancreatic B-cells. This effect occurs at a concentration (32 microM) at which phentolamine is able to enhance glucose-induced insulin secretion. The increase in cytoplasmic Ca2+ concentration caused by phentolamine is additive to the one elicited by a maximally effective concentration of tolbutamide (100 microM). Imidazoline-binding sites in insulin-secreting HIT cells can also be occupied by the guanidinium compound guanabenz, which was found to be a potent and reversible blocker of ATP-dependent K(+)-channels in B-cells. In contrast to phentolamine, guanabenz blocks the ATP-dependent K(+)-channels only in the inside-out mode, but not in the cell-attached mode of the patch-clamp technique. In conclusion, imidazolines and structurally related compounds block ATP-dependent K(+)-channels by binding to the cytoplasmic face of the plasma membrane, and may have effects on other ion channels which contribute to the elevation of cytoplasmic Ca2+ concentration and, consequently, to insulin release.

Adenosine Triphosphate↗
PubMed1991

[The emergence of the chorda tympani from the tympanic cavity and its course until its entry into the lingual nerve].

Because there are a lot of contradictory opinions in the literature we investigated the intra- and extraosseous pathway of the Chorda tympani by dissecting the heads of 6 cadavers. The Chorda nerve leaves the temporal bone in the Fissura sphenopetrosa behind the Spina ossis sphenoidalis. In an angle of 24 degrees-28 degrees the Chorda nerve connects up with the lingual nerve. The extraosseous distance is about 1.3 to 3 time longer then the intraosseous one. The individual variations of the intraosseous distance are greater than those of the extraosseous one. This is behalf the individual variations in the structure of the temporal bone.

Chorda Tympani Nerve↗
PubMed1990

[Postnatal development of the masticatory muscles of the Wistar rat (Rattus norvegicus Berkenhout). A histochemical study].

Muscle biopsies of the mandible adductors of the Wistar rat (Rattus norvegicus Berkenhout) have been analyzed enzyme-histochemically for the investigation of the postnatal development (42.-126. d post partum) of their muscle fibers with special regards to the fiber types. The following methods have been used in this investigation: myofibrillar adenosine triphosphatase (ATP-ase) with different pre-incubations, Sudan black B (triglycerides), periodic acid-Schiff reagent (PAS) (glycogen), Gomori modified Trichrome staining. Quantitative analysis of muscle fibre-type composition and muscle fibre size was done from different regions of muscle sections. Estimation of the fiber size was carried out by measuring the minimum diameter of each type of muscle fibre.

Adenosine Triphosphatases↗