PubMed Health⌕ Search

Biomedical subjects

J Svoboda

Publications and source records attributed to J Svoboda.

At least 19 recordsLinked to original sources
PubMed1992

Tumor induction by the LTR, v-src, LTR DNA in four B (MHC) congenic lines of chickens.

We report that the cloned DNA harboring the long terminal repeat (LTR), v-src, LTR proviral structure is tumorigenic in chickens of the Prague congenic lines. The growth rate of these tumors is by far the highest in the recombinant CC.R1 line, the B haplotype of which is composed of the B-F/L4 and B-G12 subregions originating from different naturally occurring haplotypes. Some of the tumors induced by the LTR, v-src, LTR DNA are repeatedly transplantable in syngeneic chickens, maintain unaltered provirus, and express v-src mRNA. Differences in the response to challenge with Rous sarcoma virus (RSV) and LTR, v-src, LTR DNA on a given experimental model are compared and possible involvement of an interaction between B-F/L and B-G region genes is considered. Regression of the LTR, v-src, LTR DNA-induced tumors did not prevent the formation and growth of tumors induced subsequently by RSV.

Animals↗
PubMed1992

Extracellular K+, pH, and volume changes in spinal cord of adult rats and during postnatal development.

Activity-related transient changes in extracellular K+ concentration ([K+]c), extracellular pH (pHc), and extracellular volume (EC volume) were studied by means of ion-selective microelectrodes in the adult rat spinal cord in vivo and in neonatal rat spinal cords isolated from pups 3-14 days of age. Repetitive electrical nerve stimulation (10-100 Hz) in adults elicited increases in [K+]c by about 2.0-3.5 mM, followed by a poststimulation K+ undershoot and triphasic alkaline-acid-alkaline changes in pHc. In 3- to 6-day-old pups, the [K+]c increased by as much as 6.5 mM at a stimulation frequency of 10 Hz, and this was accompanied by an alkaline shift. Increases in [K+]c as large as 1.3-2.5 mM accompanied by an alkaline shift were evoked by a single electrical stimulus. Stimulation in 10- to 13-day-old pups produced smaller [K+]c change and an acid shift, which was preceded by a small initial alkaline shift, as in adult rats. We conclude that glial cells buffer the activity-related [K+]c increase and alkaline pHc shifts. Mg2+ blocked the alkaline but not the acid shift. Acetazolamide had no effect on the alkaline shift but blocked the acid shift. The alkaline shift was enhanced and the acid shift blocked by Ba2+, amiloride, 4-acetamido-4'-isothiocyanotostilbene-2,2'-disulfonic acid (SITS), and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Activity-related acid shifts therefore have a complex mechanism, which includes Na+H+ exchange, Cl-/HCO3- exchange, or Na+/Cl-/H+/HCO3- antiport, Na(+)-HCO3- cotransport, and H+ efflux through voltage-sensitive H+ channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Relapsing polychondritis--ultrastructure in 2 additional cases].

A 37-year-old woman and a 74-year-old man with typical clinical history of relapsing polychondritis enabled electron microscopical analysis of various cartilages (ear, nasal septum, rib). Apoptotic lesion and degradation of chondrocytes combined not always with changes of their lacunae prevailed in both patients, fragmentation of elastic tissue in the man. Lesions of chondrocytes, a bit varied and asynchronous in intensity were observed as everywhere in a single cartilage as in cartilages from different sites.

Adult↗
PubMed1992

[Treatment of chronic uveitis with long-term administration of penicillin].

The authors followed up a group of 20 patients with chronic uveitis (10 men and 10 women), mean age 36.5 years. Despite treatment of the foci, they suffered on average from seven relapses of the disease, frequently several times in the course of one year. From the anamnestic aspect there was a significantly high number of spells of tonsillitis, respiratory infections and arthralgia. Half the cases of uveitis, mainly anterior, were bilateral. The patients suffered from dysimmunoglobulinaemia with low values of FW, ASLO, Latex. HLA B 27 was positive in five subjects. After one-year of Pendepon or Penclen administration (in half the patients with NORG) 18 patients did not develop a relapse for a period of 2-3 years. The method is simple, cheap, easy to use in field practice, in particular in junior patients. The clinical effect of treatment justifies the use of this method as an alternative of intermittent immunosuppression.

Adult↗
PubMed1991

The isopycnic, compartmentalized integration of Rous sarcoma virus sequences.

Rous sarcoma virus (RSV) can cause tumors in hamsters, which harbor complete or partially deleted RSV sequences, in their genomes. Here we have studied the localization of RSV sequences integrated into the genome of cell lines derived from six independent hamster tumors. We have found that integration occurred in the isochores richest in guanine + cytosine, of the host genome, as it had been previously observed for bovine leukemia and hepatitis B viral sequences. The integration of RSV proviral sequences is, therefore, 'isopycnic' (i.e., it takes place in host genome sequences which compositionally match the viral sequences) and compartmentalized (i.e., it occurs in a small compositional compartment of the host genome). The hamster genome compartment hosting RSV sequences precisely corresponds to a compartment of the human genome which is the most active in both transcription and recombination. The notion of a compartmentalized, isopycnic integration of RSV proviral sequences fits, therefore, with the viral integration into transcriptionally active and recombinogenic regions of the host genome observed by other authors, but is broader, in that it includes, in addition, the requirement for a compositional match between host genome sequences and expressed viral sequences.

Animals↗
PubMed1991

Extracellular space volume changes in the rat spinal cord produced by nerve stimulation and peripheral injury.

Double-barrelled potassium and tetramethylammonium-sensitive microelectrodes were used in diffusion studies with tetramethylammonium ions, which remain essentially extracellular during the measurements. Activity-related changes in the extracellular space (ECS) volume fraction (alpha), ECS tortuosity (lambda) and the dynamics of the ECS volume changes were examined in the spinal dorsal horns of rats. The alpha and lambda in L4 and L5 segments of unstimulated rats were alpha = 0.24 +/- 0.01 (i.e. ECS occupied 24 +/- 1% of the total spinal cord volume) and lambda = 1.54 +/- 0.04 (mean +/- S.D. of mean, n = 21). The values were not significantly different throughout the dorsal horn. Repetitive electrical stimulation of peripheral nerves at 3-100 Hz increased extracellular potassium concentration [( K+]e) and ECS volume in Rexed laminae III-V by 15.8 +/- 2.7% (n = 5). After the end of stimulation, when the [K+]e decreased below the original baseline (K+ undershoot), the ECS volume decreased by 20-45%. The magnitude and duration of ECS volume decrease were positively related to the stimulation frequency and duration. The ECS volume decrease was maximal at 2-10 min after the stimulation had been discontinued, and it returned to the prestimulation values in 15-40 min. The ECS volume decreased by 20-50% after injury of the ipsilateral hind paw evoked either by subcutaneous injection of turpentine (n = 5), or by thermal injury (n = 6). The maximal changes were found in Rexed laminae III-V, 5-10 min after injection of turpentine and 10-25 min after thermal injury, and persisted for more than 120 min and 30 min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Clinical aspects of the pathophysiology of HIV infection. III. Principles of therapy].

The author analyzes different possible therapeutic approaches to HIV infection in different clinical stages. He draws attention to the fact that antiretroviral therapy has always also a certain immunomodulating effect and vice versa. It is in particular necessary to pay attention to the fact that therapeutic activation of the immune system may be associated with undesirable activation of HIV replication. After giving an account of different theoretical possibilities of the therapeutic influencing of HIV infection the author analyzes hitherto assembled experience with the only treatment which can stabilize the condition in clinical practice for a certain period, i. e. administration of azidothymidine (AZT).

HIV Infections↗
PubMed1991

[Clinical aspects of the pathophysiology of HIV infection. I].

The author analyzes individual pathophysiological mechanisms which play a part in the development and clinical manifestation of HIV infection. He uses as a basis the CDC classification of HIV infections and explains on different models of clinical situations mechanisms which lead to haematological, neurological, immunological, pneumological, gastroenterological, oncological and rheumatological symptomatology.

HIV Infections↗
PubMed1991

[Clinical aspects of the pathophysiology of HIV infection. II].

The author pays attention to interindividual differences in the course of HIV infection and its causes. He emphasizes above all the influence of sex life, herpetic infections and the mental state of the patient. He analyzes also individual clinical and laboratory prognostic factors which can be used in clinical practice. In the conclusion he tries to find a way how to integrate medical care with normal life of the affected subjects and seeks prerequisites of understanding of the HIV infection, i.e. good knowledge of medicine as a whole and oneself.

HIV Infections↗
PubMed1991

[Takayasu's disease. Detection of the early systemic stage of the disease in a pregnant woman].

The authors describe the case of Takayasu's disease detected in the non-obliterating systemic stage. The disease developed in a 24-year-old woman in the 8th month of gestation and was associated with severe pain of the back and upper extremities, subfebrile temperatures, later fever and tachycardia. The authors describe the difficult diagnosis of the disease and discuss the relationship of the case with so-called fever of unknown aetiology and the development of the disease during pregnancy.

Adult↗
PubMed1990

[Immunocomplex vasculitis].

The clinician suspects immunocomplex vasculitis when he cannot find a common denominator for the concurrent affection of various neighbouring organs and tissues. These affections result from the inflammatory response of the organism to the deposition of non-phagocytized circulating immunocomplex into the vascular wall. Despite the delicacy of attempts to classify them, the author tried to differentiate them into non-progressing immunocomplexes vasculitis, which recedes, and progressing immunocomplex vasculitis which may be either primary or secondary. Among primary ones he includes nodose polyarteritis and its granulomatous variant, Churg-Strauss' disease, Henoch-Schönlein anaphylactoid purpura and granulomatous vasculitis of the Wegener granulomatosis type, Horton's temporal arteritis, Takayasu's pulseless disease and Winiwarter-Buerger's obliterating thromboangiitis, which may be of the peripheral or more rarely the visceral type. Secondary progressing vasculitis is encountered in so-called "collagenoses" (e.g. systemic lupus erythematodes), where the clinical picture is to a considerable extent conditioned by vasculitis. The clinical picture is due to the generalized affection of the microcirculation. Symptoms of ischaemic affection of all organs and tissues may be encountered. A typical feature are different types of damage of the same adjoining system, e.g. a combination of asymmetric central and peripheral pareses in affections of the nervous system. The author discusses the most frequent clinical pictures, the importance of different examination procedures and therapeutic possibilities. Assessment of the diagnosis of immunocomplex or autoaggressive systemic disease is very difficult, as a typical picture corresponding clearly to a defined nosological unit is encountered rarely.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigen-Antibody Complex↗
PubMed1990

Extracellular alkaline-acid-alkaline transients in the rat spinal cord evoked by peripheral stimulation.

Regional differences in extracellular pH (pHe) were found in unstimulated rat spinal cord using double-barrel pH-sensitive microelectrodes. The pHe in the lower dorsal horn (laminae III-VII) was about 7.15, i.e. by about 0.2 pH units lower than that measured in the cerebrospinal fluid. Transient acid shifts in pHe by 0.01-0.05 pH units were found when acute nociceptive stimuli (pinch, press, heat) were applied to the hind paw. Chemical or thermal injury evoked by subcutaneous injection of turpentine or by application of 1-3 ml of hot oil onto the hindpaw produced a long-term decrease in pHe base line in the lower dorsal horn by about 0.05-0.1 pH units. The decrease in pHe began 2-10 min after injury and persisted for more than 2 h. Electrical nerve stimulation (10-100 Hz, 20-60 s) elicited biphasic (acid-alkaline) or triphasic (alkaline-acid-alkaline) changes in pHe which have a similar depth profile as the concomitantly recorded increase in [K+]e. An initial alkaline shift by about 0.005 pH units was found to be significantly decreased by La3+, an H+ channel blocker. The dominating acid shift by about 0.1-0.2 pH units was accelerated and increased by acetazolamide (carbonic anhydrase inhibitor) showing that the high buffering capacity of the extracellular fluid may hamper the resolution of acid perturbations. Stimulation-evoked acid shifts were blocked by amiloride, SITS, DIDS and La3+ and therefore have a complex mechanism which includes Na+/H+ exchange, Cl-/HCO3- cotransport and/or Na+/Cl-/H+/HCO3- antiport and H+ efflux through voltage-sensitive H+ channels. The poststimulation alkaline shift (alkaline undershoot) was blocked by ouabain and reflects coupled clearance of K+ and H+ by active transport processes.

Acetazolamide↗
PubMed1990

Activity-related rise in extracellular potassium concentration in the brain of 1-3-day-old chicks.

The concentration of K+ [( K+]) was measured in the cerebrospinal fluid (CSF) and in the extracellular fluid [( K+]e) in the medial forebrain of two-day-old chicks by means of K(+)-sensitive microelectrodes (K-ISM). The K-ISM potential in the CSF was compared with that in artificial CSF with 3, 4 or 6 mmol/l of [K+]. The [K+] found in CSF was 3.79 +/- 0.57 (n = 8), in the hyperstriatum accessorium (HA) 3.70 +/- 0.32 (n = 13) and in the neostriatum (N) 3.51 +/- 0.32 (n = 13; mmol/l; mean +/- SEM). Trains of local electrical stimuli (10-100 Hz, 30 sec) applied to the surface of the forebrain increased [K+]e in both HA and N by 11-13 mmol/l. Increases in [K+]e in the ectostriatum (E) of 5-6 mmol/l was found in response to electrical stimulation (30-100 Hz, 5-10 sec) of the contralateral optic nerve, and of about 2 mmol/l by applying pressure to the bulb. In chicks adapted to the dark, stimulation of the contralateral eye or both eyes with bright light flashes (1-2 Hz) or with continuous light resulted in an increase in [K+]e of 0.5-1.0 mmol/l. Smaller increases in [K+]e of 0.15-1.25 mmol/l were found in HV and N after the application of a small quantity (0.1 ml) of the chemical taste aversant methylanthranilate (MeA) or the electrical stimulation of the beak by two needle electrodes inserted into the palatum or into the tongue. After application of MeA the increase in [K+]e began 3-4 min after application and persisted for 20 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Ducks: a new experimental host system for studying persistent infection with avian leukaemia retroviruses.

Long-term persistence of the avian leukosis virus (ALV), the transformation-defective mutant of Prague strain Rous sarcoma virus subgroup C (td PR-C) was established in heterologous duck hosts after infection in mid-embryogenesis. Transient viraemia was observed for about 4 weeks after hatching and was lost in most of the infected ducks by about 6 months. Loss of viraemia was accompanied by the increasing synthesis of virus-neutralizing antibodies. In spite of strong virus-neutralizing antibodies, virus was detected by the cocultivation assay in duck tissues throughout the observation period up to 5 years. In the viraemic phase of infection, we found integrated proviruses in various tissues, preferentially in stomach muscle tissue and in the thymus. The long-term persistence of virus was frequently accompanied by liver necrosis and neoplastic diseases. Injection of td PR-C virus into early embryos resulted in more pronounced infection accompanied by an increased copy number of viral DNA per cell, high mortality and remarkable atrophy of thymus tissue in infected ducklings.

Animals↗