Biomedical subjects

M Novák

Publications and source records attributed to M Novák.

At least 37 records · Page 2Linked to original sources

PubMed1996

Influence of carboxylate ions containing polymers on calcification: in vitro study.

Calcification of implant or surrounding tissues represents an important complication of its function. The role of the molecular structure of a model hydrogel on the calcification is studied here in a simple in vitro, cell free system. The results show that-COO- containing polymers have an inhibitory effect on Ca2+ crystal formation. This process seems to be unspecific, because the polymers of different structure and origin have an inhibitory effect. However, its efficiency is related to a different extent of Ca2+ binding capacity of distinct polymers.

Alginates↗

PubMed1994

Variability of changes in Doppler transmitral filling pattern during stress echocardiography in patients with stable angina pectoris.

Stress electrocardiography and echocardiography using atrial pacing together with the right-sided heart catheterization were performed in 21 patients with stable angina pectoris. Peak velocity of transmitral flow in early diastole (E) and in atrial contraction (A), deceleration time of early filling, and pulmonary artery wedge pressure were measured simultaneously at rest and immediately after each pacing frequency. Patients were divided according to their stress pulmonary artery wedge pressure changes into Group A (14 patients with an increase in pulmonary artery wedge pressure > or = 3 mmHg during stress) and into Group B (6 patients with a change in pulmonary artery wedge pressure < or = 2 mmHg during stress). One patient, T.L., with an increase in pulmonary artery wedge pressure > or = 5 mmHg after each pacing frequency was evaluated separately. In Group A patients, the non-linear course of the E/A ratio changes (from 0.78 +/- 0.06 to 0.66 +/- 0.05, P < 0.01; to 0.72 +/- 0.05, P = NS; and to 0.93 +/- 0.06, P < 0.01) and deceleration time changes (from 188.9 +/- 7.2 ms to 195.3 +/- 8.9 ms, P = NS; to 188.8 +/- 9.9 ms, P = NS; and to 154.2 +/- 6.7 ms, P < 0.01) was seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Truncated tau protein as a new marker for Alzheimer's disease.

Molecular analysis of histological hallmarks (neurofibrillary tangles, neuritic plaques, neuropil threads and dystrophic neurites) of Alzheimer diseased brain tissues showed that these lesions contain paired helical filaments. Their major constituent is microtubule associated protein tau that is in an abnormally hyperphosphorylated and truncated state. These diseased forms of tau protein are unable to promote full microtubule assembly. Understanding of the molecular basis of the processes leading to the modifications of tau proteins and paired helical filament formation will form a firm step toward rational drug development and the cure of the Alzheimer's disease.

Aged↗

PubMed1993

Transmitral flow velocities and times during stress transthoracic echocardiography in patients with myocardial ischaemia.

Twenty-nine men with chronic stable angina pectoris were investigated using stress electrocardiography (ECG) and stress transthoracic echocardiography by means of transoesophageal stimulation of the left atrium. At rest and after each stimulated frequency, ECG and 2-dimensional echocardiography combined with Doppler were performed simultaneously. Fourteen patients without ischaemia at stress ECG and two patients who were subjected only to two different frequencies of stimulation were excluded from our study. Thirteen patients with ischaemic electrocardiographic response at stress, who were subjected to at least three stimulated frequencies, were evaluated. Their deceleration time of early transmitral filling was prolonged from 171 +/- 15.4 ms to 178.1 +/- 14.4 ms (P = ns) after the first stimulated frequency, to 172.8 +/- 15.1 ms after the second stimulated frequency (P = ns) and was shortened to 143.6 +/- 7.9 ms (P < 0.05) after the fastest stimulated frequency. The ratio of peak transmitral flow velocity in early diastole (E) to that during atrial contraction (A) decreased from 0.93 +/- 0.07 at rest to 0.85 +/- 0.07 (P < 0.05) after the first stimulated frequency, to 0.87 +/- 0.07 (P = ns) after the second stimulated frequency and increased to 1.13 +/- 0.08 (P < 0.05) after the fastest stimulated frequency. In patients with angina pectoris and myocardial ischaemia, the changes in the E/A ratio and deceleration time during stress are not linear and their direction depends on the moment of their evaluation. Their use for the quantitative evaluation of the diastolic function of the left ventricle is problematic.

Adult↗

PubMed1993

[Atrial-triggered and ventricular-inhibited ventricular VDD pacing with atrial and ventricular single catheter electrodes--the Phymos MPS pacemaker].

Optimal treatment from the haemodynamic aspect in complete atrioventricular block is dual-chamber DDD pacing. It makes possible atrioventricular sequence and adaptability of the frequency of ventricular pacing to the load under the control of the sinoatrial node. DDD pacing calls, however, for an atrial and ventricular electrode on two leads. Italian authors developed in 1984 a pacemaker (PM) PHYMOS (MEDICO ITALIA) which makes possible atrial triggered ventricular VDD pacing by means of a single pass lead with a tripolar electrode. As the first ones in the post-communist countries the authors implanted to six patients a PM PHYMOS MPS. They confirmed that the advantages of the VDD system, as compared with DDD, are the use of a single pass lead. This makes the implantation quicker, simpler and safer and reduces the time of X-ray irradiation and the incidence of electrodes dislocations. Another advantage is the lower incidence of atrial fibrillation and probably also pacemaker mediated tachycardias. The disadvantages of the VDD system are that atrial stimulation is impossible and that the diameter of the single pass lead is somewhat larger. According to data in the literature and the so far small experience of the authors, when the indication is correct--atrioventricular block grade III or II with intact function of the sinoatrial node--the advantages of VDD pacing with a single pass lead, as compared with DDD pacing, predominate over disadvantages.

Aged↗

PubMed1993

Artificial mineralization in vitro--a model of tissue mineralization.

Calcium chloride and sodium hydrogen phosphate form precipitation zones in gelatin gel, gel supplemented with cartilaginous extract, articular cartilage slices, and in demineralized bone. The cartilaginous extract exerts a marked inhibitory effect on the crystal quantity and clustering. The pretreatment of cartilage slices with hyaluronidase increases the crystal frequency. The morphology of crystals formed in gelatin and in cartilage was similar but quite different from the precipitation pattern found in demineralized bone.

Animals↗

PubMed1992

Implantation of p(HEMA)-collagen composite into bone.

The replacement of bone defects is very important in clinical practice. This study compares biological properties of poly(2-hydroxyethyl methacrylate)-collagen composite with those exhibited by pure p(HEMA), an insoluble fraction of calf skin collagen (ISC-40) and demineralized bone matrix after implantation into pig or dog femurs. The levels of biodegradation or destruction of implants and healing of bone defects were studied using X-ray photography, histology and enzyme histochemistry. The results indicated a significant effect of collagen on biological destruction of the p(HEMA)-composite implants; even a minute amount of collagen influences this process dramatically. A stimulatory action of collagen on new bone formation may be of importance in bone defect healing.

Animals↗

PubMed1992

Amlodipine in patients with stable angina pectoris treated with nitrates and beta-blockers. The influence on exercise tolerance, systolic and diastolic functions of the left ventricle.

The effects of 5 and 10 mg of amlodipine and of placebo were compared in 21 patients with stable angina pectoris and multivessel coronary artery disease. The blind comparison was performed by means of bicycle ergometry and stress echocardiography using esophageal stimulation of the left heart atrium. All patients subsequently received placebo, amlodipine 5 mg and 10 mg for 2 weeks. In bicycle ergometry both doses of amlodipine in comparison with placebo significantly lowered the ST segment depression in lead V5 and prolonged the time to onset of angina. The exercise duration was significantly prolonged only after 10 mg of amlodipine. In stress echocardiography 10 mg of amlodipine significantly improved ejection fraction and reduced wall motion score during stimulation and increased peak velocity of relaxation of left ventricular posterior wall at rest and immediately after stimulation. In the patients with left ventricular end-diastolic pressure < or = 20 mmHg, amlodipine reduced the ratio of peak transmitral flow velocity in atrial contraction to that in early diastole (A/E) at rest and shortened deceleration time at rest and immediately after stimulation. Amlodipine in patients with stable angina pectoris significantly improved the exercise tolerance and the function of the left ventricle in a dose-dependent way. Amlodipine was well tolerated.

Amlodipine↗

PubMed1992

Common and different antigenic properties of the rabies virus glycoprotein of strains SAD-Vnukovo and Pitman-Moore.

Two fixed rabies virus strains, SAD-Vnukovo and Pitman-Moore (PM) were used as combined immunogens for the generation of hybridomas secreting specific monoclonal antibodies (MoAbs). The obtained hybridomas were primarily screened by an ELISA for production of MoAbs to antigen of SAD-Vnukovo strain. Six positive clones were established. A panel of MoAbs has been characterized according to reactivity in immunofluorescence, immunoblot, ELISA and neutralization tests. All MoAbs were positive in immunofluorescence when cells infected with the SAD-Vnukovo strain were used. By immunoblot, four MoAbs showed specificity for the viral glycoprotein of both SAD-Vnukovo and PM rabies strains. This pattern of reactivity indicated the existence of shared conformation-independent epitopes located on the related antigens. However, in ELISA, the tested MoAbs did not recognize viral glycoproteins of the PM strain. This indicates, that the different strain-specific conformations of the native glycoprotein determine the accessibility of the common linear determinants for respective antibodies. Only one antibody, with conformation-dependent glycoprotein specificity, was capable to neutralize the CVS strain of rabies virus.

Animals↗

PubMed1992

[Modern cardiac pacing. I. Dual-chamber pacemakers: 10 years' experience].

Dual chamber cardiac pacemakers restoring an impaired atrioventricular synchrony meet a demand of contemporary so-called physiologic cardiac pacing. 39 dual chamber (DDD) pacers were implanted in 1982-1991 in our center. They improved both well-being and hemodynamic values (doppler echocardiography) more distinctly than common ventricular demand devices did. P-wave driven ventricular pacing in normal sinus node function (in 40 per cent of our DDD patients) made a frequency response in physical exercise possible. A short atrioventricular delay in DDD pacing proved to be helpful in the treatment for reentry tachycardias refractory to antiarrhythmic drug administration. Demanding implant, high price, lengthy programming as well as a higher incidence of complications (30.7 per cent) as compared to ventricular pacemakers (7.6 per cent) were the main problems of DDD ones.

Adult↗

PubMed1992

[Modern cardiac pacing. II. Rate responsive pacemakers: clinical experience].

Rate responsive cardiac pacemakers adapting their pacing frequency according to physical effort are able to solve not only a bradycardia, but a chronotropic incompetence too. 23 rate responsive pulse generators, implanted in 1987-1991 in our center, simulated the physiological conditions and in this way they significantly improved both working capacity in bicycle stress test (p < 0.0001) and well-being in comparison with ordinary demand pacers. The incidence of complications did not exceed that in simple common pacemakers, but the rate adaptive ones were expensive and their programming was time consuming. In all three rate adaptive principles used their non-specific response revealed some imperfection of sensor driven devices. In addition, both in QT and in respiratory dependent systems their pretty proportional frequency response was delayed, while the irregular pacing rate in body activity sensor was not very proportionate to the physical exercise. The non-specific sensor response may be reduced by a combination of biologic sensors.

Adult↗

PubMed1992

Immunoblot analysis of antibody response in mice infected with Coxiella burnetii phase I.

Mouse sera collected from day 4 to day 133 postinfection (p.i.) with phase I Coxiella burnetii strain Nine Mile were analysed by immunoblotting with phase I C. burnetii cell lysate. Antibodies of IgG class protein antigens were revealed already on day 10 p.i. (60, 49 and 27 kD proteins), followed by those to 77 kD protein from day 18 p.i. and to further 7 (from 42 to 70 kD) proteins from day 28 p.i. IgG antibody reaction was observed also with 5 antigens in 14-20 kD region corresponding to lipopolysaccharides from day 22 p.i. Surprisingly, antibodies of IgM type appeared later (from day 22 p.i.) and were directed only to protein antigens, most markedly to 60 and 77 kD proteins. Differences in immunoblot patterns observed with the serum collected on day 72 p.i. before and after absorption to phase I and phase II C. burnetii cells, and to phase I cells treated by trichloroacetic acid (TCA) or KIO4, indicate the surface localization of protein phase I antigenic epitopes, which can be destroyed partly by TCA and almost completely by KIO4 treatment.

Animals↗

PubMed1992

[Comparison of the effects of diltiazem and isradipine in adrenergic beta receptor blockade in patients with stable angina pectoris].

In 20 patients with stable angina II-III according to NYHA by means of ergometry the effect of short-term administration of dilthiazem (90 mg in three doses), placebo and isradipine (5 mg in three doses) in block of beta-receptors of the sympathetic nerve (metipranolol 3 x 10 mg/day) was compared. As compared with placebo, dilthiazem and isradipine retarded significantly the development of stenocardia, reduced the S-T depression in lead V5 and increased the total work output during ergometry. Based on the results of this and previous work (9) it may be stated that concurrent administration of metipranolol reduced the frequency of side-effects of isradipine and prevented the reflex rise of the heart rate following its short-terms administration. The authors conclude that starting treatment of stable angina with isradipine is safer and more effective in combination with metipranolol than when monotherapy is used. Dilthiazem must be administered with metipranolol carefully with regard to possible development of severe bradycardia and its suitable dose should be established by titration.

Adult↗

PubMed1992

[Bispecific antibodies: present status and possibile applications].

The review article information on the current status in the research regarding bispecific antibodies. The theoretical and methodical aspects of preparation of heterohybridomas secreting bifunctional monoclonal antibodies are discussed in details. The question of purification of the antibody fraction with dual specificity is also addressed. The possible application of bispecific antibodies in human medicine for immunodiagnostics and aimed immunotherapy is described. (Fig. 7, Ref. 22.).

Antibody Specificity↗

PubMed1992

[Drug therapy in vascular occlusions of the lower extremities].

The authors report their three-year experience with application of thrombolytic treatment in 31 patients with vascular occlusions of the lower extremities. They were successful in two thirds of the patients. The authors analyze the advantages and shortcomings of systemic or selective administration of antithrombotic therapy. Concurrent administration of hyperbaric oxygen is a rational therapy.

Adult↗

PubMed1991

Analysis of human blood plasma triacylglycerols using capillary gas chromatography, silver ion thin-layer chromatographic fractionation and desorption chemical ionization mass spectrometry.

The identification and quantitation from pooled human plasma of over 50 molecular species of triacylglycerols, including 22 not previously reported, are reported. The triacylglycerols were first resolved by silver ion thin-layer chromatography into seven fractions, which were independently analysed by polarizable capillary gas chromatography and desorption chemical ionization mass spectrometry in the presence of an internal standard. The two methods gave similar values for the estimates of oligoenoic species, but the former method underestimated the polyenes (due mainly to significant losses caused by thermal degradation), and the latter method overestimated the saturates. The results show that an effective analysis of molecular species of plasma triacylglycerols cannot be obtained by either technique alone.

Chromatography, Gas↗

PubMed1991

[The effect of nifedipine and diltiazem on left ventricular function in patients with stable angina pectoris and severe left ventricular dysfunction].

In a double blind crossover five-week trial with a randomized onset in 12 patients with normal blood pressure, stable angina pectoris and more severe left ventricular dysfunction (ejection fraction less than or equal to 40%) the effect of placebo nifedipine and diltiazem on left ventricular function and tolerance of exercise was compared. The investigation was done by means of echocardiography after a load with stimulation of the heart by an oesophageal electrode. As compared with placebo, only diltiazem retarded significantly the period before development of stenocardia on stimulation of the heart. There was no significant difference between nifedipine and diltiazem as regards the effect exerted on the ejection fraction and time which elapsed after stimulation before stenocardia developed. The authors observed an unequal response of patients to the administration of nifedipine and diltiazem (some patients had less favourable findings, although they were not subjectively aware of this deterioration). Therefore these drugs must be administered to patients with angina pectoris and more severe left ventricular dysfunction with care and only if other drugs (nitrates or angiotensin convertase inhibitors) do not eliminate ischaemia and pain.

Adult↗

PubMed1991

Are the acid-labile interferon alpha and interferon omega-1 identical?

The interferon (IFN) activity found in human leukocyte IFN alpha preparations, autoimmune and AIDS sera, and others was reported to have distinct antigenic and deviating biological properties. This led to its vague designation as acid-labile and thermolabile IFN alpha. However, using specific monoclonal antibodies, the acid-labile component of IFN alpha (not exposed to pH 2) and recombinant IFN omega 1 showed significant relatedness. Monoclonal antibody T19, generated with virus-induced leukocyte IFN alpha that had not been exposed to pH 2, neutralized both the antiviral and antiproliferative activities of IFN omega-1, and vice versa; monoclonal antibody OMG 5, specific for recombinant IFN omega-1, cross-neutralized the antiviral and antiproliferative effects of the acid-labile component of leukocyte IFN alpha. When these two IFN preparations were incubated at pH 2 for 72 hr, their biological activity significantly decreased.

Animals↗