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Biomedical subjects

S Simek

Publications and source records attributed to S Simek.

35 records · Page 2Linked to original sources
PubMed1993

[Occurrence and prognosis of silent ischemia].

The authors assessed in a group of 486 asymptomatic middle-aged men (50-60 years) the prevalence of silent myocardial ischaemia. For screening they used the exercise test on a bicycle ergometer and in men with a positive test the presence of silent ischaemia was confirmed by perfusion scintigraphy with thallium-201 or by. The prevalence of silent ischaemia was compared with the incidence of angina angiography, myocardial infarction and sudden deaths in a similar group of 1419 men followed up for 10 years in the same department. In patients with a confirmed diagnosis of silent ischaemia the prognosis was monitored, as well as possible clinical manifestations of IHD, in the course of 4-7 years of the investigation. The presence of silent ischaemia was confirmed in 32 men, i.e. 6.6%. As compared with other forms of IHD, silent ischaemia was detected almost equally frequently as myocardial infarction and as compared with angina pectoris it was observed twice as frequently. In the course of the investigation period two patients were subjected to a revascularization (CABC or PTCA). In the remaining group of 30 patients who underwent conservative treatment two patients died (sudden deaths), seven developed angina and five myocardial infarctions (incl. one clinically silent).

Adult↗
PubMed1992

[Noninvasive diagnosis of coronary spasm].

The objective of this work was to compare the sensitivity of non-invasive tests used for the diagnosis of variant angina pectoris (VAP). In a group of 38 patients with VAP the authors compare the sensitivity of the cold test (CT), hyperventilation test (HT), handgrip (HG), bicycle ergometry (BE) and a newly suggested combination of hyperventilation with HG and BE resp. The authors evaluated first the sensitivity of ST elevations which are an entirely specific sign and in particular denivelization of ST (by depression or elevation) which is a less specific sign. The sensitivity of different tests was as follows: CT 5% and 5% resp., HT 18% and 39% resp., HG 13% and 29% resp., BE 26% and 66% resp., HV+HG 37% and 63% resp., HV+BE 50% and 87% resp. Then the authors assessed the sensitivity of repeated examinations HV+HG 47% and evaluation during denivelization of ST 63%, HV+BE 66% and 89% resp. The authors evaluated moreover the sensitivity of ST elevations in patients according to the activity of the disease. Patients with at least five stenocardias per week had a higher sensitivity, as compared with patients with less frequent attacks: HV+HG 42% and 25% resp., HV+BE 60% and 33% resp. The highest sensitivity was found in a combination of HV+BE. Repetition of the test in case of a negative result increased markedly the sensitivity, a higher sensitivity was found also in patients with more frequent stenocardias.

Adult↗
PubMed1989

[The role of beta-endorphins in silent forms of ischemic heart disease].

Silent--asymptomatic--ischaemia is one of the forms of ischaemic heart disease. Present possibilities of non-invasive diagnostics are based primarily on long-term ECG monitoring. With regards to the hypothesis that the raised algesic threshold at high level of analgetically reacting beta endorphins seems to be the pathophysiologic basis of this particular syndrome, we tried to verify the presumption by administering a beta-endorphin antagonist-naloxon. In 13 patients with a silent form of ischaemic heart disease (absence of stenocardia in objectively proved ischaemia in loading test) we made the loading test in a standard form and after administering of 2 mgs of naloxan intravenously. Owing to the fact that stenocardia developed only in one patient after endogenous opiate effect blockage we presume that pathophysiologic basis of this syndrome must be discovered elsewhere.

Coronary Disease↗
PubMed1988

p59v-rel, the transforming protein of reticuloendotheliosis virus, is complexed with at least four other proteins in transformed chicken lymphoid cells.

Previous studies have identified the protein product of v-rel, the oncogene carried by reticuloendotheliosis virus (REV), as a 59,000-dalton phosphoprotein located predominantly in the cytosol of transformed chicken lymphoid cells. In immune precipitates of p59v-rel, there is a closely associated protein kinase activity. In chicken lymphoid cells that do not contain REV, p68c-rel is found free in the cytosol not associated with other proteins and not detectably phosphorylated. In this study, we found that immune precipitates of 59v-rel from REV-transformed cells contain at least four other proteins, of approximate molecular weights 124, 115, 68, and 36 kilodaltons (kDa). The 124-, 115-, and 36-kDa proteins are apparently unrelated to p59v-rel in sequence, and their coprecipitation suggests that they are complexed with p59v-rel. The coprecipitating 68-kDa protein was found to be p68c-rel, which, like the other three proteins, precipitates by virtue of its association with p59v-rel. Glycerol gradient analysis suggested the presence of more than one type of complex: one containing p115, p68c-rel, p59v-rel, and p36, and another containing p124, p115, p59v-rel, and possibly p68c-rel. In vitro kinase activity was found in all size classes, coinciding with the distribution of p115 and p59v-rel. The complex(es) was stable under a variety of conditions, including a wide range of ionic strengths, chelators, and detergents, and through multiple cycles of immune precipitation and elution. This suggests a specific and functionally significant interaction among the members that may be of direct relevance to the mechanism of REV-induced transformation.

Animals↗
PubMed1988

Detection and characterization of the protein encoded by the chicken c-rel protooncogene.

We have identified the protein encoded by chicken c-rel, the cellular homolog of the v-rel oncogene carried by reticuloendotheliosis virus. The protein has been detected in two avian lymphoid cell lines and in chick embryo fibroblasts. It has a molecular weight of 68,000, suggesting that the viral gene (which encodes a protein of 59,000 molecular weight) is a truncated form of its cellular homolog. The c-rel protein is found in the soluble cytoplasmic fraction of chicken lymphoid cells and is not associated in any stable way with other cellular proteins. Unlike the viral protein, p68c-rel is not detectably phosphorylated.

Acetylglucosaminidase↗
PubMed1986

Detection and characterization of the protein encoded by the v-rel oncogene.

To identify the protein encoded by v-rel, the oncogene of reticuloendotheliosis virus (REV-T), antisera have been raised to three synthetic peptides derived from the translation of our previously published v-rel DNA sequence [R.M. Stephens, N.R. Rice, R.R. Hiebsch, H.R. Bose, Jr., and R.V. Gilden, Proc. Natl. Acad. Sci. USA 80, 6229-6233 (1983)]. Sera to all three peptides precipitate a 59,000 Da protein from REV-T-transformed chicken lymphoid cells. This protein is not detectable in uninfected chick embryo fibroblasts, and its observed size is in good agreement with the 56,000 Da predicted by the DNA sequence. We conclude that this protein is the v-rel product and designate it p59rel. To search for evidence of post-translational processing of this protein, cells were grown in the presence of glycosylation inhibitors. These resulted in no detectable difference in the size of p59rel. Nor was its size detectably altered during the course of a pulse-chase experiment. Growth of cells in the presence of [32P] orthophosphate, however, revealed that p59rel is a phosphoprotein. It is also closely associated with a protein kinase activity, for precipitation with one of the peptide antisera (but not the other two) resulted in strong kinase activity in the immune complex pellet. During this reaction, p59rel itself becomes phosphorylated. Kinase activity was retained in the immune complex following detergent and high salt washes, leaving open the possibility that p59rel is itself a kinase.

Acetylglucosaminidase↗
PubMed1982

In situ hybridization: general infectivity assay for retroviruses.

We have devised a general infectivity assay for retroviruses. A virus-specific [32P]DNA probe is hybridized in situ to a monolayer culture, and foci of infected cells in the monolayer are detected by exposure of the hybridized culture to X-ray films. The method is quantitative, in that it gives the same titer for Moloney murine leukemia virus as does the standard UV-XC test. The specificity of the assay is indicated by the fact that murine leukemia virus and baboon endogenous virus do not cross hybridize under the conditions used. The assay is completed within 1 to 3 weeks and should be broadly applicable for retroviruses which replicate without altering cellular morphology: its use is demonstrated with mouse mammary tumor virus and the helper virus of the reticuloendotheliosis complex.

Animals↗
PubMed1980

Analysis of the nucleic acid components in reticuloendotheliosis virus.

Reticuloendotheliosis virus (REV) is known to be capable of transforming chicken bone marrow cells in vivo and embryo fibroblasts in vitro. As with spleen necrosis virus, we have found that sequences related to REV are found in DNA of several uninfected avian species. For example, about 15% of the [3H]cDNA synthesized in the endogenous reverse transcriptase reaction reassociated with DNA of uninfected chickens. Kinetic analysis revealed only a few (less than five) such sequences per haploid genome, and the thermal stability of the reassociated duplex indicated less than perfect complementarity. Comparison of REV propagated in an avian cell line with REV grown in a canine line has revealed clear differences between the two isolates. Viral RNA and [3H]cDNA of REV isolated from the transformed chicken bone marrow cell line appear to consist of at least three sequence classes. The most numerous of these classes is highly related to REV propagated in canine cells. Only slightly less abundant is a class unrelated to RNA isolated from the canine virus but highly related to sequences found in normal uninfected avian cellular DNA. A third component is present at about 1% the level of the most numerous class. Although REV appears to be unrelated to the other known avian retroviruses, distant relatedness between p30's of REV and various mammalian type C viruses has recently been reported. We have asked whether REV-related sequences can be detected in various mammalian DNAs and viral RNAs. Hybridization experiments performed at low stringency have revealed no such sequences.

Animals↗
PubMed1978

Detection of proviral DNA in horse cells infected with equine infectious anemia virus.

Equine infectious anemia virus (EIAV) recently has been shown to possess a high-molecular-weight RNA genome and a virion reverse transcriptase. We completed the demonstration that EIAV is a retrovirus by showing the presence of proviral DNA in equine cells infected in vitro, but not in normal horse DNA. These studies were performed by using a highly representative cDNA probe synthesized by the virion polymerase. It was found that this cDNA reassociated extensively, and with high thermal stability, with either viral RNA or DNA extracted from infected cells, but showed no detectable reassociation with DNA from uninfected horse cells. Similarly, sequences related to EIAV were neither found in the DNA of four other Equus species, nor in a variety of other mammals including sheep, cows, pigs- dogs, cats, and humans; nor did EIAV cDNA hybridize with a variety of other retrovirus RNAs. These experiments were performed under conditions of very low stringency to enable detection of distantly related sequences, with a sufficient ratio of DAN to cDNA to allow detection of less than one viral copy per haploid genome. We conclude that EIAV is not an endogenous virus of the horse or of the other species tested.

Animals↗
PubMedDate not supplied

Local changes in the plasma endothelin level in the coronary artery immediately after percutaneous transluminal coronary angioplasty.

Endothelin plays an important role in cardiovascular pathology. As one of the most important endothelium-derived vasoconstrictor substances, endothelin together with endothelium-derived vasodilating factor control vascular tone and contribute to the vasoconstrictory response if the production of endothelium-derived vasodilating factor is impaired. The aim of the study was to assess the changes of the local endothelin level in coronary circulation immediately after percutaneous transluminal coronary angioplasty (PTCA). Plasma endothelin levels were measured in blood samples from the peripheral vein and ostium of the coronary artery before the angioplasty, and from the distal coronary artery just beyond the dilated segment and the peripheral vein immediately after the procedure. The plasma endothelin level was significantly higher in the ostium of the coronary artery already prior to PTCA as compared to the peripheral vein (10.9 +/- 3.4 vs. 7.2 +/- 2.1 pg/ml, p < 0.005). There was no change in the endothelin level in the coronary artery distal to the dilated segment immediately after the procedure as compared to the initial level, although this level was higher than the postangioplasty venous level (9.8 +/- 2.9 vs. 7.7 +/- 2.0 pg/ml, p < 0.005). Individual changes in coronary-artery plasma endothelin levels as a response to coronary angioplasty were disparate. An increase and a decrease in coronary artery plasma endothelin levels by more than 2 pg/ml after coronary angioplasty were observed in 3 and 6 subjects, respectively. In conclusion, increased plasma endothelin levels were found in blood samples drawn from the coronary artery as compared to the peripheral vein. There was no further change in the plasma endothelin level in the coronary artery distal to the dilated segment after angioplasty; however, the individual responses were disparate.

Adult↗