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Biomedical subjects

G Farkas

Publications and source records attributed to G Farkas.

At least 73 records · Page 4Linked to original sources
PubMed1993

Mechanics of the parasternal intercostals in prone dogs: statics and dynamics.

It is well established that the parasternal intercostal muscles in supine dogs play a major role in causing the inspiratory elevation of the ribs. This posture, however, is not physiological in the dog. In the present study, we measured the electromyographic (EMG) activity and the respiratory changes in length of these muscles in the prone (standing) and supine postures in seven anesthetized spontaneously breathing dogs. With a change from the supine to the prone posture, the parasternal intercostals showed a 3.2% reduction in their relaxation length (Lr), but their mechanical behavior was essentially unchanged. Thus, the muscles continued to shorten below Lr during inspiration and to lengthen beyond Lr during expiration. With the adoption of the prone posture, the amount of parasternal inspiratory EMG activity and the amount of inspiratory muscle shortening each increased by 30-35%. Furthermore, when the parasternal intercostal in a single interspace was selectively denervated, the shortening of the muscle during inspiration in both postures was virtually eliminated. These observations indicate that in the dog the parasternal intercostals still play a major role in causing the inspiratory elevation of the ribs in the prone posture. These observations also suggest that these muscles in prone animals continue to operate on the descending limb of their length-tension curve.

Animals↗
PubMed1993

Ontogenesis of estrogen secretion by porcine fetal testes.

High levels of estrogen secretion is a characteristic of steroidogenesis in the pig testis in both the adult and newborn male. We have now examined the ability of fetal gonads to secrete estrogens, and compared it with testosterone secretion during prenatal development. Fetuses were recovered from sows (N = 33) at 27-114 (term) days of gestation. Gonads were removed for organ culture in TC-199 medium, or used as minced tissues or free cell preparations when taken later in development. Organ cultures were maintained for 96 h with luteinizing hormone added for the last 72 h for one gonad of each pair. Estrone, estradiol-17 beta and testosterone were measured by radioimmunoassay in media samples. Trace amounts of estrone were detected almost as early as testosterone secretion commenced, but quantities sufficient for confirmation by radioimmunoassay after chromatography were not seen until day 35 of gestation. Estrogen production increased to > 0.37 nmol.gonad-1.4 h-1 at term. Testosterone secretion in organ culture was increased by luteinizing hormone but no effect was seen on estrone levels for the first half of pregnancy. Thus, estrogen secretion is a feature of steroidogenesis in the porcine testes even in the early stages of fetal development.

Animals↗
PubMed1992

Inhibition of DNA binding by the phosphorylation of poly ADP-ribose polymerase protein catalysed by protein kinase C.

Purified type II (beta) and type III (alpha) protein kinase C phosphorylates highly purified polyADP-ribose polymerase in vitro whereby 2 mols of phosphate are transferred from ATP to serine and threonine residues present in the 36 and 56 kDa polypeptide domains of the polymerase protein. Calf thymus DNA was a non-competitive inhibitor of the protein kinase C catalyzed phosphorylation of polyADP-ribose polymerase. Coincidental with the phosphorylation of the protein the polymerase activity and DNA binding capacity of polyADP-ribose polymerase were inhibited. These in vitro findings may have possible cell biological significance in cellular signal transduction.

Adenosine Triphosphate↗
PubMed1992

[Tumor necrosis factor production in septic conditions following pancreatitis (preliminary report)].

Detectable TNF levels in sera 33% of patients with sepsis following pancreatitis have been found. No correlation was observed between serum TNF concentration and the severity of illness. However, monocytes and granulocytes of septic patients exerted higher TNF-mediated cytotoxicity than leukocytes of normal blood donors. The in vitro TNF-producing capacity was also higher in the patients in the study group, and it decreased only before fatal outcoming of sepsis. Our results suggest that determination of the TNF-producing capacity of leukocytes might be more informative than measurement of the serum TNF level in the evaluation of the severity or prognosis of sepsis.

Cytotoxicity, Immunologic↗
PubMed1992

Synthetic oligopeptide substrates which fail to compete with H1 histone for type II and type III isoenzymes of protein kinase C.

1. The oligopeptide AAASFKAKK which contains recognition motifs similar to that found in the surrounding of the site of H1 histone phosphorylated by protein kinase C is unable to compete with H1 histone for the type II and type III isoenzymes, though it is a good substrate for protein kinase C and it is able to compete with a physiological substrate of the enzyme. 2. Among several oligopeptides tested as an alternative substrate a very basic peptide proved to be the most effective inhibitor of H1 histone phosphorylation. This oligopeptide substrate contains basic recognition motifs at both sides of the phosphorylated residue at variance with the sequence of H1 histone in the surrounding of the phosphorylated site.

Amino Acid Sequence↗
PubMed1991

[Incidence of fungal infection in surgical diseases of the pancreas].

Recently the number of mycotic infections has increased significantly. Authors have observed 13 mycotic infections on operated patients suffering pancreatic diseases between 1984 and 1990. 9 of 13 patients had pancreatic abscesses as well. The risk factors of fungal infections are analysed. It is important to take differentiation between fungal colonisation and septicaemia caused by yeasts. Repeated microbiological examinations can promote recognising of the fungal invasion. The base of the therapy is to avoid risk factors of infections and to use antifungal medication in time.

Abscess↗
PubMed1991

[A case of inflammatory fibroid polyp of unusual localization].

The case of an inflammatory fibroid polyp of infrequent localization is presented. Altogether 100 cases are reported by summarizing publications in the literature and only a small part of them showed duodenal localization. The patient whose case is presented was subjected to internal examination and later to operation because of acute spastic abdominal pain and loss of weight. Following the description of the case the authors analyse the etiology of this rare disease and the problems of terminology. Radical, curative operation is considered expedient in these cases. The presented case can be regarded as a special one both from the viewpoint of diagnostics and of its duodenal localization.

Duodenal Neoplasms↗
PubMed1991

The 38 kDa Ca2+/membrane-binding protein of pig granulocytes needs a high Ca2+ concentration to be phosphorylated by protein kinase C.

The 38 kDa Ca2+/membrane-binding protein reported to be the dominant substrate of protein kinase C in the extracts of pig neutrophil granulocytes was purified partially and its phosphorylation was investigated. In pig granulocytes type II protein kinase C was the major isoform, while type III isoenzyme was present only as a minor activity. Phosphorylation of the 38 kDa protein was performed with rat brain protein kinase C. Each of the three isoenzymes purified from rat brain was able to phosphorylate this protein, though on the conditions used in our experiments it was phosphorylated most intensively by type II protein kinase C. A phospholipid-dependent, but Ca2(+)-independent, form of protein kinase C was demonstrated with the aid of a synthetic oligopeptide substrate. Phosphorylation of the 38 kDa protein by the Ca2(+)-independent enzyme proceeded exclusively in the presence of Ca2+. The Ca2+ concentration necessary for the phosphorylation of the 38 kDa by either form of protein kinase C was by orders of magnitude higher than that required for the activation of protein kinase C.

Amino Acid Sequence↗
PubMed1991

[Ruptured retroperitoneal bile duct cyst. An extremely rare injury after blunt abdominal trauma].

Management of a retroperitoneal extrahepatic bile duct cystenteric tear at a cystenteric malformation of the intra- and extrahepatic ducts (Todani IV-A) discovered during an emergency surgical procedure following an accident is presented and the problems associated with bile duct cysts are discussed. It is pointed out that acute treatment with a simple and safe method (external Kehr-T drainage) can be successful when injuries are present, although most trauma surgeon are seldom, and many never, directly confronted with injuries attributable to these extremely rare malformations.

Abdominal Injuries↗
PubMed1990

Displacement chromatography on cyclodextrin-silicas. III. Enantiomer separations.

The feasibility of preparative enantiomer separations by displacement chromatography on analytical-scale beta-cyclodextrin-silica columns, operated in the reversed-phase mode, was demonstrated using the enantiomers of mephobarbital, hexobarbital, dansylleucine, dansylvaline and dansylphenylalanine as model solutes. The method development scheme (which relies on the determination of the elution-mode retention behavior and the adsorption isotherms of the solutes and the candidate displacers) described in Parts I and II can be used to select the appropriate displacers and the conditions leading to a successful displacement chromatographic separation. The importance of the displacer (both type and concentration) to the success of the displacement chromatographic separation is demonstrated.

Amino Acids↗
PubMed1990

The long-term cultivation and cryopreservation of human fetal pancreatic tissue.

Fetal human pancreatic islets were cultured and cryopreserved for long periods (18 weeks and 6-8 months, respectively). Multiplication of the cells was observed, and later differentiation as well. The growth characteristics and insulin-like immunoreactivity were evidenced by light microscopy, immunocytochemistry, electron microscopic examinations and measurement of the total insulin content. These results indicate that the cultivation and storage of fetal islets by cryopreservation are hopeful procedures for future human islet transplantation.

Cryopreservation↗