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Biomedical subjects

M Moravec

Publications and source records attributed to M Moravec.

At least 19 recordsLinked to original sources
PubMed2003

Left retroperitoneal versus transperitoneal approach for abdominal aortic surgery - retrospective comparison of intraoperative and postoperative data.

BACKGROUND: The aim of our study was to evaluate the potential advantages of the left retroperitoneal (RP) approach for abdominal aortic surgery and compare the aortic exposure with the transperitoneal (TP) approach which is widely used. PATIENTS AND METHODS: Total 55 consecutive patients who underwent elective aortic surgery between 1998 and 1999 were evaluated retrospectively. Thirty three patients underwent the RP exposure and 22 the TP approach in the treatment of abdominal aortic aneurysm or aortoiliac occlusive disease. Demographic data and premorbid status were not significantly different between these two groups. Fourteen intraoperative and postoperative parameters were monitored and statistically analyzed. RESULTS: We found statistically significant differences in three of 14 intraoperative and postoperative parameters. Patients operated with the RP approach to the abdominal aorta were able to take clear fluids orally sooner. A statistically significant difference was also detected in the postoperative extubation time as RP patients were extubated almost one hour sooner than TP patients. Bowel function onset was statistically significantly faster return in the RP group. In the rest of recorded data there were no significant differences, however in all of follow-up parameters we found results in favour of RP group. CONCLUSION: We conclude that the RP group of patients had statistically significant improvements three of 14 postoperative clinical parameters. (Tab. 3, Ref. 18.)

Aorta, Abdominal↗
PubMed2002

[Pedal bypass in the treatment of ischemic diabetic foot].

AIM: The aim of this retrospective analysis was assessment of both patency and limb salvage rates of diabetic ischemic feet which underwent pedal bypass surgery within the period of 3 years. MATERIAL AND METHODS: Authors evaluated 50 critically ischemic diabetic feet where the pedal bypass was indicated for limb salvage. Total 41 pedal bypasses were performed and median follow-up was 16.7 months (1-39). The free muscle transfer were performed either in one session with or subsequently after the pedal bypass surgery in six limbs. RESULTS: Authors achieved 61% and 76% graft patency and limb salvage rates, respectively, within the median 16.7 months follow-up. All successfully revascularised feet healed up within the median period of 3 months postoperatively. No patient died within 30 days postoperatively. CONCLUSION: We conclude, that pedal bypass is safe procedure with acceptable limb salvage rate in the medium-term follow-up. Surgeons can markedly extend an indication criterions for limb salvage by exploiting of this technique.

Adult↗
PubMed1998

3-D characterization of ganglion cells of the terminal nerve plexus of rat atrioventricular junction.

Three-dimensional (3-D) morphology of neurons of the terminal nerve plexus of the atrioventricular junction was examined in a scanning electron microscope. Distributions of different cell types encountered as well as their relations to different structures of the atrioventricular specialized tissue were also studied. Most neurons were found disseminated in a thin connective tissue layer separating different segments of the atrioventricular conductive tissue from the interventricular septum. Sometimes, they formed small pluricellular ganglia (up to 5 neurons) but, frequently, they occurred isolated in the terminal ramifications of the intramural nerve plexus of specialized tissue. Some intranodal neurons could also be identified. According to their 3-D morphology, nerve cells of the perinodal ganglionated plexus could be divided into three categories: (1) Large unipolar neurons were scattered throughout the atrioventricular junction. Their long and thin axonal projections were often directed towards the interventricular septum. (2) Large pseudounipolar or bipolar neurons were located at a few specific loci, namely all along the bundle of His and its bifurcation into the right and left bundle branches. Frequently, they occurred solitary and immersed amongst strands of surrounding muscle cells. Only occasional synaptic impacts could be identified on the surface of neuronal bodies of these bipolar neurons. On the other hand, their dendritic varicosities were richly innervated. Due to their irregular shape, intimate association with muscular elements and their topographical superposition with occasional spindle-like structures, these nerve cells recall prospective sensory neurons involved in integration of mechanical and neural stimuli to the heart. (3) Small multipolar interneurons could be identified in the retronodal ganglion and within right and left bundle branches. The present description of morphological heterogeneity of intramural nerve cells agrees with recent morphological and functional classifications of autonomic neurons and supports the idea that, at the level of the atrioventricular junction, a self-governed neuronal network may be operating.

Animals↗
PubMed1998

Palmitate oxidation by the mitochondria from volume-overloaded rat hearts.

In this work, an attempt was made to identify the reasons of impaired long-chain fatty acid utilization that was previously described in volume-overloaded rat hearts. The most significant data are the following: (1) The slowing down of long-chain fatty acid oxidation in severely hypertrophied hearts cannot be related to a feedback inhibition of carnitine palmitoyltransferase I from an excessive stimulation of glucose oxidation since, because of decreased tissue levels of L-carnitine, glucose oxidation also declines in volume-overloaded hearts. (2) While, in control hearts, the estimated intracellular concentrations of free carnitine are in the range of the respective Km of mitochondrial CPT I, a kinetic limitation of this enzyme could occur in hypertrophied hearts due to a 40% decrease in free carnitine. (3) The impaired palmitate oxidation persists upon the isolation of the mitochondria from these hearts even in presence of saturating concentrations of L-carnitine. In contrast, the rates of the conversion of both palmitoyl-CoA and palmitoylcarnitine into acetyl-CoA are unchanged. (4) The kinetic analyses of palmitoyl-CoA synthase and carnitine palmitoyltransferase I reactions do not reveal any differences between the two mitochondrial populations studied. On the other hand, the conversion of palmitate into palmitoylcarnitine proves to be substrate inhibited already at physiological concentrations of exogenous palmitate. The data presented in this work demonstrate that, during the development of severe cardiac hypertrophy, a fragilization of the mitochondrial outer membrane may occur. The functional integrity of this membrane seems to be further deteriorated by increasing concentrations of free fatty acids which gives rise to an impaired cooperation between palmitoyl-CoA synthase and carnitine palmitoyltransferase I. In intact myocardium, the utilization of the in situ generated palmitoyl-CoA can be further slowed down by decreased intracellular concentrations of free carnitine.

Adenosine Triphosphate↗
PubMed1997

Control of oxidative metabolism in volume-overloaded rat hearts: effect of propionyl-L-carnitine.

The objective of the present work was the assessment of metabolic events responsible for the improvement of hemodynamic function of volume-overloaded hearts from rats receiving propionyl-L-carnitine. A severe cardiac hypertrophy was induced in 2-mo-old rats by surgical opening of an aortocaval communication. Three months later, during in vitro perfusions with 1.2 mM palmitate, 11 mM glucose, and 10 IU/l insulin, the mechanical performance and overall energy turnover (myocardial O2 consumption) of hypertrophied rat hearts were significantly decreased under conditions of moderate and high workloads. These changes in cardiac energetics paralleled the decrease in total tissue carnitine content and alterations in exogenous palmitate oxidation. The oxidative utilization of glucose was also slightly depressed in volume-overloaded hearts while steady-state glycolysis rates increased, especially in hearts subjected to high mechanical loads. This slowing of metabolic pathways involved in acetyl-CoA generation resulted in decreased NADH availability and in an apparent substrate limitation of oxidative phosphorylation suggested by a failure of cytosolic unbound ADP to drive respiration. Long-term administration of propionyl-L-carnitine normalized the degree of reduction of mitochondrial pyridine nucleotides and improved the kinetics of mitochondrial ATP production in volume-overloaded hearts. The resulting acceleration of energy turnover was essentially related to improved oxidative utilization of glucose, but steady-state palmitate oxidation rates also increased in severely hypertrophied hearts. This concomitant acceleration of glucose and palmitate oxidation may be related to the particular experimental conditions (high exogenous palmitate concentrations, elevated workloads) used in this study. We assume that the increase in intracellular carnitine, together with a stimulation of acetyl-CoA demands related to high workloads, creates conditions that are compatible with the simultaneous relief of pyruvate dehydrogenase and carnitine palmitoyltransferase I. The resulting increase in the rate of steady-state ATP production improves, in turn, the mechanical activity of volume-overloaded hearts.

Adenosine Diphosphate↗
PubMed1996

Linking reengineering to revitalization.

A health care organization that embarks on reengineering without a strategy for revitalizing is courting disaster. What does it take to get reengineering right? It takes vision, unflinching commitment, new kinds of leadership and business strategies, and new behaviors to challenge the old manager-physician power dynamic. A low-cost health care provider must be able to promote trust, partnerships, and competencies that are specifically linked to accessible, cost-effective patient care.

Career Mobility↗
PubMed1990

Catecholaminergic and peptidergic nerve components of intramural ganglia in the rat heart. An immunohistochemical study.

Immunohistochemical properties of the terminal nerve network in the rat heart were assessed by use of the elution-restaining method. The colocalization of the enzymes involved in catecholamine synthesis (tyrosine hydroxylase--TH. dopamine-beta-hydroxylase--DBH) as well as the respective distributions of the neuropeptides associated with the adrenergic nervous system (neuropeptide tyrosine--NPY, C-terminal flanking peptide of neuropeptide Y--C-PON) were studied in series of serial sections throughout the interatrial septum and the atrioventricular junction. Our data suggest that ganglion cells of sulcus terminalis as well as the epicardial ganglia enclosed between the superior vena cava and ascending aorta are VIP- and TH-negative, but neuropeptide Y- and DBH-immunoreactive. They give rise to three intraseptal nerves directed towards the specialised structures of the atrioventricular junction. These nerve fascicles contain abundant, thick TH-immunoreactive nerve fibres and scarce, thin NPY- and DBH-immunoreactive fibres. The cell bodies of the intramural ganglion cells localized between the right and left branches of the bundle of His (Moravec and Moravec 1984) are strongly TH- and DBH-immunoreactive. They are innervated by thick nerve fibres having the same immunohistochemical properties (NPY- and DBH-immunoreactivities) as those of a subpopulation of the epicardial ganglion cells and seem to supply some of the TH-immunoreactive nerve fibres directed via the intraseptal nerves to the epicardial ganglia. The existence of a multicomponent nerve network, characterized by a reciprocal innervation of the sinus node and atrioventricular node areas, is suggested by our immunohistochemical data.

Animals↗
PubMed1990

Catecholamine-synthesizing enzymes and neuropeptides in rat heart epicardial ganglia; an immunohistochemical study.

The subepicardial atrial ganglia of rat hearts were examined using immunohistochemical techniques and antibodies against the catecholamine-synthetic enzymes tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH), and the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and met-5-enkephalin (ENK). Some of the ganglion cells present in the ganglia exhibited DBH-like immunoreactivity (LI) and NPY-LI, whilst these cells never exhibited TH-, VIP-, CGRP-, SP- or ENK-LI. Groups of small cells exhibiting an intense TH-LI, corresponding to cells referred to as catecholamine-containing cells and sometimes small intensely fluorescent cells in the literature, were observed in the ganglia. A subpopulation of these cells exhibited immunoreactivity to one of the neuropeptides tested, namelyu SP. Only a few of the cells showing TH-LI displayed DBH-LI. Nerve fibres showing SP-, CGRP-, DBH- and TH-LI were present in the ganglia; some of these fibres being closely associated with the ganglion cells or with the cells showing TH-LI. The observation provide new information on the catecholamine-synthetic enzyme/neuropeptide expression of the ganglion and catecholamine-containing cells and of the associated nerve fibres of rat heart subepicardial ganglia.

Animals↗
PubMed1989

Adrenergic neurons and short proprioceptive feedback loops involved in the integration of cardiac function in the rat.

Serial cryostat and paraffin-embedded sections through the atrioventricular junction of the rat heart were studied at the light-microscopic level after indirect immunohistochemical staining (tyrosine hydroxylase, neuropeptide Y, C-terminal flanking peptide of neuropeptide Y immunoreactivities) or silver impregnation. The distribution of these immunoreactivities in the Hissian ganglion (Moravec and Moravec 1984) as well as the relationships of the Hissian ganglion cells with the surrounding structures have been studied to assess its function. The results suggest that the Hissian ganglion is composed of large multipolar neurons displaying both tyrosine hydroxylase (TH) and related peptide (neuropeptide Y. C-terminal flanking peptide of neuropeptide Y) immunoreactivities. The dendritic projections of these adrenergic cells penetrate the reticular portion of the atrioventricular node and the upper segments of the interventricular septum where they constitute sensory-like corpuscles. The hypothesis that the adrenergic neurons of the atrioventricular junction are involved in short proprioceptive feedback loops necessary for beat-to-beat modulation of cardiac excitability and intracardiac conduction can thus be suggested.

Adrenergic Fibers↗
PubMed1986

Intrinsic neurosecretory neurons of the rat heart atrioventricular junction: possibility of local neuromuscular feed back loops.

The microanatomy and ultrastructure of rat heart atrioventricular junction were studied on serial sections of both paraffin and epoxy embedded samples. The animals were pretreated with 5-hydroxy-dopamine in order to differentiate the adrenergic component of the terminal nerve plexus. Two kinds of ganglia could be identified throughout the interatrial septum by the optical microscope. The first was composed of large pale cells with voluminous nuclei. The other resembled acini-like clusters of osmophilic cells. Another small ganglion was invariably present between right and left branches of the bundle of His. The electron microscopic examination of this structure revealed, apart from small pale neurons (10 microns in diameter), several large 5-hydroxy-dopamine contrasted neurosecretory cells (up to 30 microns) with abundant electron dense vesicles typical for sympathetic neurons. Numerous glomeruli with dendrodendritic and axodendritic connections, some of which exhibit the same 5-hydroxy-dopamine loaded vesicles, could be found in the vicinity of the specialized conducting tissue. The functional implications of the above morphological data are not clear. However, the intrinsic neurosecretory component can be expected to modulate both specialized cells and neighbouring neurons. The heterogeneity of neuro-neuronal and neuro-muscular relations, such as perinodal mechanoreceptors, may suggest that the terminal nerve plexus not only distributes the efferent stimuli, but that it also has an integrative function which is the necessary prerequisite for a local feed back autoregulation.

Animals↗
PubMed1985

Terminal nervous plexus of the atrioventricular junction of the rat. Microanatomical aspects and regional specialization.

The paraformaldehyde-fixed hearts of adult rats were embedded in paraffin. Serial sections throughout the interatrial septum and the atrioventricular junction were examined in the optical microscope after having been silver stained. The density and the distribution of different nervous elements in the perinodal nerve plexus were studied and the results compared with the electron-microscopic data. These data confirm that at the level of the atrioventricular junction, a dense terminal network can be seen. It is composed of both terminal nerve fibers and ganglionic cells forming a small ganglion adjacent to the lower edge of the bundle of His and a thin ganglionic lamina in the interatrial septum. Apart from small neurons, previously described as cholinergic, large neurosecretory cells could also be demonstrated in some of the serial thin sections through the Hissian ganglion. The neuromuscular junctions between the terminal nerve fibers and specialized cells exhibit regional specialization. While the distal portion of the atrioventricular node and the bundle of His receive essentially efferent fibers, afferent coiled endings prevail in the reticular portion of the atrioventricular node and in the adjacent interatrial septum. Similar structures, larger in diameter, can also be seen around the muscular fibers and around the capillaries of the interventricular septum. The functional significance of the aforedescribed regional specialization of the terminal innervation of the atrioventricular junction is briefly discussed.

Animals↗
PubMed1984

Intrinsic innervation of the atrioventricular junction of the rat heart.

Alternate serial semithin and thin sections of the glutaraldehyde-fixed interatrial septum and atrioventricular junction of adult rat were examined in light and electron microscopes. The animals were pretreated with a false precursor of catecholamines, i.e., with 5-OH-dopamine, in order to differentiate the adrenergic component of the intrinsic nervous system. According to the light microscope data, two kinds of ganglia can be distinguished at the level of the interatrial septum. Those of the first kind are composed of large pale cells with voluminous nuclei. Those of the other kind resemble acinuslike clusters of small osmiophilic cells. Another small ganglion is invariably associated with the distal edge of the bundle of His. At the electron-microscope level, two types of ganglionic cells are found in the meshes of the peri- and intranodal plexus: 1) small neurons (10 microns) with richly developed neuropiles, and 2) large 5-OH-dopamine contrasted neurosecretory cells (up to 25 microns) containing electron-dense vesicles typical of sympathetic neurons. Numerous glomeruli with dendrodendritic and axodendritic connections are also found in the vicinity of the specialized tissue; and, in the nodal interstitium, several clusters of small chromaffin cells (5 microns) and a network of multipolar satellite cells similar to the interstitial cells of Cajal can be distinguished. Our data suggest that the microanatomical and cytological organization of the terminal innervation of the node of Aschoff-Tawara and of the bundle to His resembles that of the myenteric plexus. The physiological significance of these ultrastructural data for the local control of electrophysiological properties of the atrioventricular junction is briefly considered.

Animals↗
PubMed1981

Some morphological aspects of the atrioventricular junction in the rat heart.

The interrelationships of different components of atrioventricular junction of the rat heart were examined on serial sections. The results are the following: 1) The atrioventricular node of the rat is situated at the level of membraneous septum separating left ventricular cavity from the right atrium. This particular localization may be of functional significance since at this level both the state of systemic arterial circulation and venous return, can be integrated. 2) Apart from the node of Aschoff-Tawara adjacent to the upper edge of muscular septum, an accessory atrioventricular node is regularly present close to the aortic root. 3) In the proximity of both atrioventricular nodes we found vascular lacunae containing abundant mastocytes and chromaffin cells. These pictures seem to suggest the existence of local chemoregulation and transmitter liberation. 4) His bundle is apposed to subendocardial fibrous lamina running from mitral valve to the cartilaginous ring of the aortic root. This association of specialized cells with their connective environment reminds the organization of different mechanoreceptors described in literature.

Animals↗