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P Fiala

Publications and source records attributed to P Fiala.

At least 37 records · Page 2Linked to original sources
PubMed1993

Are there any differences in the excitation-contraction coupling of the working myocardium of adult and newborn guinea-pigs?

Action potentials (APs) and the force of isometric contractions of the right ventricular papillary muscles were measured in adult and newborn guinea-pigs. The measurements were carried out in the steady state with the rate of stimulation of 0.1, 1, and 2 Hz, and further some measurements were done in which Sr2+ was substituted for Ca2. The duration of APs of the newborn animals without pharmacological treatment was significantly shorter in comparison with that of the adults at all the used stimulation frequencies. An analogous sensitivity was found in the contractile force to increased stimulation frequency and when the steady state stimulation was discontinued by the insertion of interpolated extrasystoles in papillary muscles of adult or newborn animals. The biphasic contractions of papillary muscles were evoked in both groups of animals by the incomplete substitution of Sr2+ by Ca2+ in the presence of isoprenaline. The early component of the biphasic contractions had a faster course as compared to the late component and disappeared in the presence of caffeine in both groups of animals. Our results suggest that the heart cells of newborn guinea-pigs probably possess the sarcoplasmic reticulum (SR), whose function does not differ in quality from that of the adult guinea-pigs. The postnatal prolongation of APs is therefore not probably the result of postnatal development changes of the functions of SR, but could be related to changes in the relations between the surface and volume of the heart cell during its growth.

Action Potentials↗
PubMed1993

[Structure of compact bone and types of stress in the long bones in humans].

The authors elaborated a new macroscopic method which made it possible to analyze the orientation of osteons in the entire diaphysis. All long bones of the human extremities were thus analyzed. In each bone the osteons are arranged in a specific pattern but according to a uniform plan. Most of them are oriented in an oblique direction and are arranged as two helices of opposite directions located on opposite sides of the bone. The two fields are separated by a sharp borderline. Biomechanical analysis revealed that the orientation of the osteons is consistent with the direction of the maximal principal stress which depends on the normal and torsional stress to which the bone is exposed. From the orientation of osteons the authors derived ex post the mode of dominant loading of all long bones: the femur is exposed to bending in the medial direction and to outer rotation, the tibia is exposed to bending in dorsal direction and to inner rotation. The humerus is bent in the medial direction, the radius in the dorsal one. Both these bones are exposed to loading in inner rotation. In the ulna and fibula the mode of stress could not be assessed by the authors' method. The results are summarized in two diagrams which indicate the orientation of osteons and the way in which the long bones in man are exposed to load. The authors discuss the theoretical and practical impact of these findings.

Bone and Bones↗
PubMed1993

Principal types of functional architecture of cancellous bone in man.

The cancellous bone architecture in man is locally specific. Several principal types can be distinguished, depending on the kind of loading and movement in the joint in one, two or more directions. Under multidirectional load the spongiosa trabeculae form spatial fans seen as two crossing systems on plane sections. Marked differences exist between the bone structure under concave joint surfaces and the convex ones. The analysis testifies the correctness of the author's own theory on the development of the cancellous bone architecture. According to this theory every trabecular system corresponds to other direction of maximal principal stress in the course of movement. Both crossing systems in the metaphysis are pressure systems, corresponding to opposite extreme positions in the joint. Tension systems can be found in sites of ligament or tendon insertions and closely under concave articular surfaces only.

Bone Development↗
PubMed1993

[Endoscopic wedge-shaped lung biopsy--initial experience].

The authors publish their initial experience with wedge-shaped pulmonary biopsy by the endoscopic route. The group is formed by 18 patients who were indicated for the operation on account of a disseminated pulmonary process in order to assess the micromorphological appearance of the affected lung tissue. Two patients developed a complication during operation which therefore was completed by minor thoracotomy. In who patients the authors observed after operation slow expansion of the pulmonary parenchyma. No death after the operation was recorded. The authors assume, based on their initial experience, that this operation will soon be included among common diagnostic operations and will help to facilitate the diagnosis and selection of treatment in patients with disseminated lung disease.

Adult↗
PubMed1992

[Extended pulmonary resection in non-small cell lung cancer].

The authors give an account of their experience with extensive pulmonary resections on account of an extensive non-small-cell carcinoma of the lungs. During a 13-year period (1976-1988) they made 140 extensive resections of the lungs. As to histological characteristics, the epidermoid type of tumour predominated. The tumour spread most frequently to mediastinal nodes and the thoracic wall. The mean age of the patients was 54.9 years, the mortality within 30 days after operation 5.7%. The five-year survival of patients after operation was evaluated in patients operated between 1976 and 1988 when 90 operations were performed. The majority of patients (32.5%) survived combined surgery. Two patients survive after 10 years. Due to the small number of patients and their difficult comparability it is not possible to evaluate the effectiveness of different types of treatment statistically. In the literature views on combined postoperative treatment differ, a randomized study would be useful. In the conclusion the authors advocate continuation of the hitherto used trend of therapy, they recommend introduction of new chemotherapeutic agents in close collaboration with oncologists and concentration of patients in specialized departments.

Adult↗
PubMed1992

[Complications of mediastinoscopy examinations].

In 1970-1990 in the Institute of Lung Diseases in Prague a total of 180 mediastinoscopies were performed. In the submitted paper the authors discuss 169 of these examinations. In this group 20 examinations were associated with a peroperative or postoperative complications, i.e. a total of 12% of the examinations. However, only in three patients, i.e. cca 1.8% from the total number serious complications were involved which were unequivocally specific for mediastinoscopy. In two instances massive haemorrhage occurred from lacerated mediastinal vessels associated with superior vena cava syndrome and in one case pneumothorax developed. All these complications were controlled by surgical intervention made in time. The most frequent complication after mediastinoscopic examination was retention of a serohaematoma in the wound--this was recorded 11 times. The cause of its development is the method of preparation and anatomical conditions in the pre- and paratracheal space. The percentage of this complication can be reduced by using active drainage of the mediastinum.

Adolescent↗
PubMed1991

Aminopeptidases and angiotensin I-converting enzyme activities in primary human lung tumors and lung parenchyma.

The activities of alanyl aminopeptidase (AAP), arginyl aminopeptidase (RAP), alpha-glutamyl aminopeptidase (EAP) and angiotensin I-converting enzyme (ACE) were investigated in primary human lung tumors of different histological types and in matched lung parenchyma. In contrast to the studied aminopeptidases whose activity differences between tumor and lung tissues were infrequently significant, the activity of ACE was decreased highly significantly in the majority of lung tumors.

Adenocarcinoma↗
PubMed1991

[Hemothorax as a complication of thoracotomy].

In 1969 to 1989 in the Research Institute of Tuberculosis and Respiratory Diseases in Prague a total of 3583 thoracotomies were performed. Of these during the postoperative period 29 patients were re-operated on account of continuing haemorrhage into the pleural cavity. This is approximately 0.8% of all thoracotomies. Sixteen patients had to be re-operated within 12 hours after operation, 12 patients were re-operated later than 12 hours after operation but within 24 hours, one patient was re-operated later than 24 hours after operation. The cause of haemothorax was in the first place capillary haemorrhage from a lacerated pleura, in the second place haemorrhage from a severe intercostal artery at the very site of the thoracotomy. Other causes of haemorrhage such as haemorrhage from the bronchial artery and its branches are not frequent. None of the patients had to be re-operated on account of haemorrhage from the major arteries of the pulmonary hilus. Administration of small doses of heparin before and after operation did not influence the number of re-operations on account of haemothorax.

Hemothorax↗
PubMed1991

[Diagnosis of diabetes mellitus based on the renal biopsy].

In a total of 1499 representative renal biopsies 30 displayed morphological changes suggesting diabetic nephropathy. Six patients had clinically diagnosed diabetes at the time of biopsy, 20 according to the bioptic finding, and in four patients the examination did not confirm diabetes. The authors describe the morphological vascular changes in particular the cumulation of masses resembling the mesangial matrix and basal membranes, as well as hyaline lesions, their development, site and combinations. In the author's opinion the most reliable sign of early diabetic nephropathy is thickening of the glomerular basal membrane. They draw attention to the non-specific character of the morphological finding and the necessity to diagnose diabetes mellitus by clinical and in particular by laboratory methods.

Biopsy, Needle↗
PubMed1990

Mixed hepatoblastoma in the adult: morphological and immunohistochemical findings.

A case of mixed hepatoblastoma in a 66-year-old man is discussed. Assessment of malignant mesenchymal and malignant epithelial elements yields the diagnosis. In the reported case, the epithelial area consisted of fetal hepatocytes. Distinct ductal differentiation, chondroid and even asteoid metaplasia were recorded. The morphological and immunohistochemical findings observed in the given patient are compared with data published in the world literature.

Aged↗
PubMed1990

Mechanical and electrical manifestations of the papillary muscles of verapamil-treated adult guinea-pigs under steady state conditions and after a pause.

The authors studied the effect of verapamil in 10(-7) to 10(-4) mol.l-1 concentration on the duration of action potentials (AP) and the corresponding isometric contractions (MG) from the right ventricular papillary muscles of adult guinea-pigs. In the steady state, using stimulation frequencies of 0.1, 1 and 2 Hz, verapamil caused dose- and use-dependent shortening of the AP plateau phase (D0) in 10(-5) and 10(-4) mol.l-1 concentration; lower concentrations did not affect the D0. With all the given concentrations, the MG fell in relation to the dose and the stimulation frequency. The pause regimen was defined by the induction of a steady state at 1 Hz frequency, followed by the interpolation of a pause lasting 5 s to 600 s and its effect was studied on the first and second AP after the pause and on the corresponding MG, without any pharmacological treatment and in the presence of verapamil (10(-5) mol.l-1). In the absence of the drug, slight lengthening of the D0 and weakening of the MG, proportional to the length of the pause, occurred after the pause. In the presence of verapamil, the first post-rest contraction after a 10 s pause attained five-fold the value in the steady state, while the second post-rest contraction was much weaker than the first. The possibility that verapamil acts on intracellular links in calcium metabolism, and of disproportion of its effect on the D0 and on contractility when it is administered in low concentrations, is discussed. The most likely mechanism of this effect is the presence of a negative feedback between calcium release from the sarcoplasmic reticulum and membrane electrogenesis.

Action Potentials↗
PubMed1990

[Bronchopleural fistula as a complication of pulmonary resection].

During a 15-year period, when in the department for thoracic surgery in the Research Institute for Tuberculosis and Respiratory Diseases 1612 resections of the lungs were performed, the authors recorded 18 patients with bronchopleural fistulae. After pneumonectomies and lobectomies the incidence of this complication was recorded in 1.4%. The majority of fistulae was observed after resection on the lungs on account of bronchogenic carcinoma, in two patients after resection on account of a pulmonary aspergilloma. After resection on account of TB and bronchiectas is the authors did not observe bronchopleural fistulae. Treatment of the fistula was in two thirds of the patients of the investigated group conservative with a 33% lethality. In six patients on account of the fistula rethoracotomy was performed with a lethality of 66.6%. The total lethality during treatment of bronchopleural fistulae was 44.4%. The purpose of the present work is to draw attention to the serious character of this post-resection complication and to its possible prevention by preoperative preparation and surgical technique.

Bronchial Fistula↗
PubMed1990

[Congenital nephrotic syndrome].

Only one case of congenital nephrotic syndrome was recorded in a series of 2,500 bioptic examinations of the kidney performed over a period of 20 years. In necroptic material examined over the same period of time congenital nephrotic syndrome was recorded three times. At the first bioptic examination of the kidneys only minimal changes of glomeruli were diagnosed. Rebiopsy exhibited proliferation of mesangial cells, focal segmental glomerular sclerosis, cystically dilated tubules in the juxtamedular region of the cortex, and focal tubulointerstitial reactive changes, which in accordance with the clinical findings were assessed as congenital nephrotic syndrome of the Finnish type. Comparison of the findings observed at the first biopsy and at rebiopsy demonstrates the importance of proper collection of a representative sample for renal biopsy.

Female↗
PubMed1989

[Diagnosis and classification of tubulointerstitial nephritis].

To make a correct diagnosis of tubulointerstitial nephritis and to make it in time calls for knowledge of its clinical symptomatology (it is usually very marked in acute forms and in chronic forms it is frequently inapparent) and it is essential to know the main causes which produce this type of renal damage. In some instances the already developed disease is diagnosed and not infrequently even renal failure. Recognition of the aetiological and pathogenetic multiplicity of the disease, as made possible by the submitted classification of the WHO expert commission, is one of the prerequisites of the diagnosis and treatment in time or of prevention by effective provisions.

Humans↗
PubMed1987

Influence of a period of inactivity on the duration of post-rest action potentials of the mammalian working ventricular myocardium in correlation to the preceding stimulation frequency.

Experiments were carried out on the working right ventricular myocardium of adult cats, guinea-pigs and rabbits. Membrane voltage was recorded by the glass microelectrode technique and the preparations were stimulated with frequencies of 5, 1 and 0.2 Hz. After a steady state had been reached, a pause (TP) lasting 10-600 s was interpolated. The influence of TP on the duration (D) of post-rest action potentials (AP) was studied; the effect of the pause was measured at electric zero level (D0) and at further repolarization levels (-20, -40 and -60 mV, given here as D-20, D-40 and D-60). At 1 and 0.2 Hz frequency, the cat myocardium displayed lengthening of the AP proportional to the duration of the pause; at 5 Hz frequency, D0 reacted by lengthening up to TP = 120 s and to further pauses by slight shortening. D-60, at all frequencies, lengthened throughout the whole of the given TP range. The rabbit myocardium, at all the given frequencies, reacted up to TP = 60-120 s by marked shortening of post-rest AP at all repolarization levels; with longer pauses the AP lengthened. At 5 Hz frequency the guinea-pig myocardium reacted similarly to the cat myocardium; at the lower stimulation frequencies, the pause-induced changes in the post-rest AP were less strongly expressed. In all the given types of myocardium, the most pronounced post-rest AP reactions were those at electric zero level (the plateau phase of the AP); towards more negative repolarization values and with lower pre-pause stimulation frequencies they were less strongly expressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1983

Electromechanical relationships of rabbit papillary muscle under interpolated extrasystole conditions and after a pause.

The aim of the study was to describe and attempt to explain certain specific features of electromechanical coupling in the rabbit myocardium. Electromechanical correlations in the papillary muscles of the right ventricle of adult rabbit hearts were studied by a programmed stimulation technique. The duration of action potentials (AP) was measured in the plateau phase (Do, ms) and at -80 mV level (D80, ms), together with the intensity of the corresponding isometric contractions (MG, arbitrary units). After twenty AP of 1 Hz frequency, we interpolated an extrasystole with a variable interval (TE = 100-900 ms) and measured D0 and MG of the premature AP and the first AP of the subsequent cycle. When a steady state at 1 Hz frequency had been reached, we interpolated pauses (Tp) of 5 to 600 s and read D80 and MG of the first to the tenth contraction after the pause. The extrasystole D0 attained the maximum at TE = 260 ms and then fell abruptly. The MG of extrasystoles with a longer TE grew from the lowest value (0.3), attained 1 at TE = 700 ms and then remained stable. The first contraction after extrasystole displayed distinct postextrasystolic potentiation (MG = 2), while D0 was unwontedly short. Prolongation of TE was accompanied by an increase in its D0 value and by a steep drop in MG (to as little as 0.2). D80 of the first AP evoked after the pause fell proportionally to log Tp and then, from Tp = 60 s, gradually rose. The MG value of the first contraction after the pause fell proportionally to log Tp. The AP recovered much more rapidly than contractility from the effect of the pause. In the discussion, an attempt is made to explain the found correlations on the basis of differences in the behaviour of the calcium current channel system in the rabbit myocardium and a commentary on electromechanical correlations is based on the hypothesis that the free sarcoplasmic calcium level determines both membrane electrogenesis and the inotropic state.

Action Potentials↗