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Biomedical subjects

B Kocsis

Publications and source records attributed to B Kocsis.

At least 73 records · Page 4Linked to original sources
PubMed1990

Combined treatment of anaplastic astrocytoma (grade 3-4) with diacetyl-dianhydro-galactitol (DADAG).

Autoradiographic studies of labeled diacetyldianhydro-galactitol (DADAG) with tumor bearing animals revealed that the CNS accumulates high amounts of DADAG-derived radioactivity and the elimination from the brain seems to be relatively slow. This observation and the activity of DADAG against murine ependymoblastoma classified the drug as a promising agent for the treatment of malignant brain tumors. In a series of 30 evaluable consecutive patients who were operated on for anaplastic astrocytomas, DADAG has been applied during and subsequent to postoperative radiotherapy. No severe toxicity occurred. Survivals were compared with a group of patients who got irradiation alone. Statistical analysis did not show significantly better survivals in the DADAG treated group: median value was 46.5 weeks, p = 0.232.

Adult↗
PubMed1990

Comparison of methods eliciting cerebral ischaemic pressor response in the cat.

Three methods of intercepting the blood supply to the brain were tested by means of X-ray angiography and by monitoring the pressor response following cerebral ischaemia. The methods were: (1) occlusion of carotid and basilar artery; (2) occlusion of carotids and vertebral arteries in the cervical canal of the third vertebra; (3) occlusion of carotid and subclavian arteries. The X-ray angiographs showed that in most cases we could close the accessory sources of the cerebral circulation and drastically reduce the blood supply to the brain of the cat. With all three methods the cerebral ischaemia evoked strong blood pressor elevation, which was weaker however when the carotid and basilar artery were clamped, in comparison with the other two methods. This may be explained by the existence of small arteries supplying the lower brain stem and originating intracranially from the vertebral artery near to the junction of the vertebral and anterior spinal artery.

Animals↗
PubMed1990

Relationships between activity of sympathetic nerve pairs: phase and coherence.

The coherence function and phase spectrum were used to study the relationships between the discharges of sets of two postganglionic or preganglionic sympathetic nerves in baroreceptor-denervated cats anesthetized with either 5,5-diallylbarbiturate-urethan or alpha-chloralose. Most of the power in sympathetic nerve discharge was contained between 2 and 6 Hz. The coherence values relating the activity of two nerves were significantly different from zero within this frequency band. The phase spectrum was either linear or complex (i.e., showed changes in slope) within the coherent frequency band. We observed three patterns of relationship. The first pattern was characterized by a constant interval between activity in different sympathetic nerves within the coherent frequency band. The second pattern was characterized by a frequency-dependent interval. The third pattern was characterized by uncoupling of the 2- to 6-Hz rhythms in the discharges of different nerves. Switching between these patterns was observed. We suggest that the three patterns reflect different functional states of the central system responsible for the 2- to 6-Hz rhythm. Two models of this system are entertained. The first model is one of a system of coupled oscillators while filtering circuits that receive common inputs are the elements of the second model.

Animals↗
PubMed1990

Coherence of medullary unit activity and sympathetic nerve discharge.

Analyses in the frequency and time domains were used to study the relationships between the discharges of single brain stem neurons and postganglionic sympathetic nerves in baroreceptor-innervated and -denervated cats anesthetized with 5,5-diallylbarbiturate-urethan. Spike-triggered averaging was used initially to identify single neurons with sympathetic nerve-related activity in the medullary lateral tegmental field, rostral ventrolateral medulla, and medullary raphe. The discharges of such neurons were correlated to the 2- to 6-Hz rhythm in sympathetic nerve discharge (SND). Frequency-domain analysis revealed that the relationship between medullary unit activity and the sympathetic nerve rhythm was not fixed from cycle to cycle. First, the coherence values relating the activity of these neurons to SND were closer to zero than to unity in most cases. Second, whereas most of the power in the autospectra of SND was contained between 2 and 6 Hz, that in the autospectra of medullary unit activity was more evenly distributed over a much wider frequency band. These and other observations indicate that the 2- to 6-Hz rhythm is an emergent property of a network of brain stem neurons whose discharges are probabilistically rather than strictly related to the phases of the population rhythm.

Animals↗
PubMed1990

Forebrain rhythm generators influence sympathetic activity in anesthetized cats.

Autospectral and coherence analyses were used to study the frequency-domain relationships between frontal-parietal cortical activity [electroencephalogram (EEG)] and the discharges of the interior cardiac and renal sympathetic nerves of baroreceptor-denervated and vagotomized cats anesthetized with either alpha-chloralose or pentobarbital sodium. Delta slow-wave activity in the EEG was correlated to sympathetic nerve discharge (SND) as shown by sharp peaks between 0.5 and 4 Hz in the coherence function. The relationship was stronger in chloralose- than in pentobarbital-anesthetized cats. Coherence of the two signals could be attributed to descending influences of forebrain delta slow-wave generators on sympathetic circuits, since midbrain transection preferentially reduced the power in SND at frequencies that cohered to the EEG before transection. In contrast, the power in the EEG was not reduced by midbrain transection. The relationship between cortical delta slow-wave activity and SND was stronger during than between cortical spindlelike events that lasted 1-3 s and recurred once every 5-10 s. These events were similar to cortical spindles observed during the early stages of sleep and under light barbiturate anesthesia. These observations raise the possibility that the influences of forebrain delta slow-wave generators on SND are gated by thalamic mechanisms normally involved in the sleep-wake cycle.

Anesthesia↗
PubMed1990

Peripheral B-lymphocyte markers and function in IgA nephropathy.

Peripheral blood B-lymphocyte markers and functions were observed in 21 patients with IgA nephropathy (IgA NP) and in 16 controls. IgA NP B lymphocytes expressed significantly higher positivity with Leu 1 (CD 5) monoclonal antibody than controls. CD 5 positive B lymphocytes are thought to be a distinct subset of the B cells (autoregulatory B lymphocytes) inducible in IgA NP by lipopolysaccharide (LPS) stimulation parallel to the higher expression of surface IgM heavy chain positivity. The activated state of IgA NP B lymphocytes has been proved by their higher OKIa (HLA-DR) positivities but lower IOB1a (CD 21, C3d-receptor) and decreased IgG-Fc-receptor (ox-rosette) expression. IgA NP B lymphocytes showed a higher IgA but also IgG and IgM polyclonal immunoglobulin production than control B lymphocytes in co-cultures with T lymphocytes. Not only regulatory T lymphocyte subsets but also serum derived from IgA NP patients stimulated the immunoglobulin production of IgA NP B cells.

Adult↗
PubMed1989

Two-phase change of sympathetic rhythms in brain ischemia, Cushing reaction, and asphyxia.

The present study was designed to determine the extent to which the brain stem neural networks, normally capable of synchronizing the sympathetic nerve discharge (SND) into 2- to 6- and 10-Hz rhythmic fluctuations, contribute to the control of autonomic reactions during brain hypoxia and/or hypercapnia. Vertebral, cardiac, and renal nerve discharges were recorded electrophysiologically in 34 anesthetized, curarized, and artificially ventilated cats. The sympathetic nerve responses to cerebral ischemia (elicited by reducing the blood supply to the brain), intracranial pressure elevation (Cushing reaction), and systemic asphyxia were tested with special focus on the rhythmic structure of the SND. It has been found that there are two phases of SND changes during cerebral ischemia differing mainly in the frequency content of the signals and less in the compound action potential amplitude. During the first phase the rhythmic generators controlling the tonic sympathetic outflow are more strongly activated, which is reflected in a stronger, more regular, and more widespread manifestation of these rhythms on the efferent neurograms. After some time the normal SND structure abruptly changes to a desynchronized activity with loss of the three main sympathetic rhythms and responsiveness to baroreceptor reflex activation. The same stereotyped changes can be observed regardless of the way in which the brain hypoxia and/or hypercapnia has been produced. Nor does the denervation of peripheral baro- and chemoreceptors substantially alter the general pattern of the responses.

Animals↗
PubMed1989

Aimed application of antibiotics in treating hand infections.

Surgical exploration is of prime importance in treating hand infections. In addition, it is essential to apply up-to-date and adequate antibiotic treatment. Authors employed antibiotics during the treatment of hand infections of 65 various aetiologies and types by considering the antibiotic sensitivity spectrum of the most frequent pathogens as also the effective concentration of the antibiotic acting in the inflammatory focus. For assessing effective antibiotic concentrations, samples were collected during exploration from the inflammatory tissues, and based on their assessments, it was pointed out that an adequate inhibitory antibiotic concentration cannot be reached by each antibiotic by applying it in the usual dose and way. The use of certain antibiotics is recommended in view of the most frequent pathogens of hand infections, of the spectrum of the antibiotic selected by the authors as well as in that of the measured tissue antibiotic concentrations in the dosage used by them. The effective application as well as dosage are also published. Regarding that, in practice, antibiotic treatment should be started according to the nature of the disease without knowing the spectrum of resistance and the pathogen, it is considered important for them to select initially, beside the surgical treatment, an antibiotic which is probably effective and is capable of entering in a sufficient amount the focus of inflammation.

Anti-Bacterial Agents↗
PubMed1988

[Effects of electron radiation on lung tissue in the postoperative irradiation of breast carcinoma].

The changes in lung tissue density arrived during the postoperative irradiation of 21 patients between February, 1984 and March, 1985 were investigated by means of a computer tomograph type Medicor-Pfizer 0100. It was shown that the influence of ionizing radiation produced an increased density of the pulmonary tissue even in case of the most precise radiophysical plan and the optimum energy. In all cases the density measured by CT after the irradiation was higher than before radiotherapy. This might be a very early sign of radiogenic late effects. An adequate modification of the irradiation plan has therefore to be carried out in the manner of a feedback.

Adult↗
PubMed1987

Characterization of the very late cardiosympathetic A-reflex in high-mesencephalic cats.

In unanaesthetized mid-collicular decerebrate cats, stimulation of low-threshold afferents running in the inferior cardiac nerve can evoke in renal nerve a long-latency reflex response, which is able to reduce or overcome the inhibition developing after the late response. The spatial and temporal summation have great importance in generating this very late response (VLR). Increasing the stimulus intensity and the frequency of the impulses, using short trains or a previous A + C tetanic stimulation of the segmental inputs considerably increased the chance of the VLR overcoming the late inhibition.

Afferent Pathways↗
PubMed1986

Activity of peripheral sympathetic efferent nerves in experimental subarachnoid haemorrhage. Part I: Observations at the time of intracranial hypertension.

The origin and pathomechanism of vegetative disturbances in patients suffering from subarachnoid haemorrhage are not completely clarified. Since some of these alterations in vegetative functions may well be attributed to acute changes in sympathetic activity, we initiated a study to investigate this modality in experimentally induced subarachnoid haemorrhage. Experiments were performed on 51 cats, anaesthetized with alpha-chloralose and urethane, immobilized and artificially ventilated. Compound electrical discharges of the left vertebral, cardiac and renal sympathetic nerves, ECG, EEG, end-tidal CO2, systemic arterial blood pressure and intracranial pressure were recorded on a polygraph. Subarachnoid haemorrhage was simulated by the injection of 1-5 ml of fresh, autologous blood into the cisterna magna. Mock cerebrospinal fluid was also injected as a control. Our results showed that in induced subarachnoid haemorrhage, not the blood itself but the intracranial pressure elevation might be responsible for the strong increase in sympathetic efferent activity. With the direct recording of the electrical activity of the three sympathetic nerves, we were able to verify the sympathetic overactivity underlying the cardiovascular disturbances during intracranial pressure elevation. Regarding the mechanism of the overactivity, most probably not the ischaemia or hypoxia, but the mechanical distortion of the medulla could be the adequate stimulus of the sympathetic overactivity and the Cushing response during intracranial pressure elevation.

Animals↗
PubMed1986

Activity of peripheral sympathetic efferent nerves in experimental subarachnoid haemorrhage. Part II: Observations during the "early vasospasm" period.

The efferent activity of the vertebral, cardiac and renal sympathetic nerves was recorded during the so-called "early vasospasm" period, 25-30 minutes after experimentally induced subarachnoid haemorrhage. Experiments were performed on 51 cats with methods described in Part I of our publication. The animals were held either in a sphynx-like position (Pos. I), or in head-down position (Pos. II), when the level of the cisterna magna was 2-3 cm below the level of the spinal cord, facilitating the injected blood to flow in to, and remain at the base of the brain. According to our results during the "early vasospasm" period, we could not observe such changes in the sympathetic efferent activity, which could be specific for this period. With the gradual decrease in the intracranial pressure, the sympathetic overactivity ceased, and in most cases the level of activity was similar to that of the preinjection period. Our results also indicate that because of the remarkable variability of the activity of the renal sympathetic nerve during the intracranial pressure elevation, recording the activity of one sympathetic nerve only may give misleading results concerning the activity of the whole sympathetic system.

Animals↗
PubMed1986

Dibromodulcitol-based combined postoperative chemotherapy of malignant astrocytomas and glioblastomas.

Continuing our earlier studies with dibromodulcitol (DBD), in a series of 38 evaluable consecutive patients who were operated on for malignant supratentorial gliomas, radiotherapy with smaller daily but higher total doses of DBD has been started 3-5 weeks after surgery. This was followed alternately by a combination chemotherapy of CCNU and DBD or CCNU and Procarbazine. No severe myelotoxicity occurred. Survivals were compared with a group of patients who got irradiation alone. Statistical analysis showed a significantly better survival in the presently treated group: median survival was 55 weeks, p = 0.02. These values were very similar to those groups which were treated by intermittent DBD schedule during irradiation. This study seems to confirm our previous suggestion that the concurrent use of DBD during irradiation might be an important factor in improving survival times.

Adult↗
PubMed1985

Real-time blood pressure monitoring in physiological experiments using an Apple II microcomputer.

The paper describes a program used for real-time blood pressure monitoring. A simple method allowing interactive control of the decision criteria is used for upstroke detection. The blood pressure signal is characterized by means of 8 parameters, computed for every cycle. The program offers two graphic modes: plotting (a) the original signal and (b) the computed variables. Other useful programs are presented together with the BP/MONITOR to allow use of the Apple II as a digital memory scope in different working modes.

Animals↗
PubMed1984

Isolation of adenosine 5'-diphosphate-L-glycero-D-mannoheptose, the assumed substrate of heptose transferase(s), from Salmonella minnesota R595 and Shigella sonnei Re mutants.

From heptose transferase-less Re mutants of Salmonella minnesota and Shigella sonnei, a mixture of nucleotide-linked heptoses was isolated. After paper chromatography in different solvent systems, ADP derivatives of D-glycero-D-mannoheptose and L-glycero-D-mannoheptose could be isolated in pure form. The structure of ADP-L-glycero-D-mannoheptose was verified by analytical methods and by transformation of ADP-D-glycero-D-mannoheptose with ADP-D-glycero-D-mannoheptose-6-epimerase.

Adenosine Diphosphate Sugars↗