Biomedical subjects

A Lányi

Publications and source records attributed to A Lányi.

At least 19 recordsLinked to original sources

PubMed2000

SH2D1A and SLAM protein expression in human lymphocytes and derived cell lines.

The gene defect responsible for the X-linked lymphoproliferative disease (XLP) is associated with an impaired control of Epstein-Barr virus (EBV) infection. The gene has been recently identified and the encoded protein (designated SH2D1A, DSHP or SAP) was characterized. It is a 128 amino acid (aa) protein, containing a single Src homology 2 (SH2) domain. It interacts with signaling lymphocytic activation molecule (SLAM) expressed on the surface of activated T and B cells. We show that activated T, but not activated B, cells express the SH2D1A protein. NK cells express the protein as well. Tumor lines originating from B, T or NK cells exhibited similar SH2D1A protein expression as the corresponding normal cells, with some notable exceptions. EBV-carrying, tumor phenotype representative (type I), but not EBV-carrying lymphoblastoid cell line (LCL)-like (type III) or EBV-negative Burkitt lymphoma (BL) lines expressed SH2D1A. The phenotypic switch from type I to type III in the EBV-carrying BL line Mutu was associated with a down-regulation of SH2D1A and up-regulation of SLAM. In contrast to normal ex vivo and long-term activated NK cells, 2 of 3 NK leukemia lines expressed SLAM. All 3 lines expressed SH2D1A, like their normal counterparts.

Amino Acid Sequence↗

PubMed1999

Disruption of functions of wild-type p53 by hetero-oligomerization.

We report that a p53 segment (p53 del 1-293) containing the oligomerization domain interferes with the functions of wild-type p53. Wild-type p53 inhibits transcription mediated by human cytomegalovirus (CMV) immediate-early promoter significantly; however, co-expression of p53 del 1-293 drastically reduces this repression. We show that wild-type p53 forms hetero-oligomers with p53 del 1-293 suggesting that the hetero-oligomers are defective in repressing the CMV promoter. A synthetic promoter with p53-binding sites is transactivated significantly by wild-type p53. However, co-expression of p53 del 1-293 drastically reduces this activation. At a high concentration, a deletion mutant of wild-type p53 (del 393-327) defective in oligomerization transactivates efficiently a promoter with synthetic p53-binding sites. This transactivation remains unaffected by co-expression of p53 del 1-293. p53 del 393-327 also fails to hetero-oligomerize with p53 del 1-293 indicating that hetero-oligomerization is necessary for disruption of wild-type p53-mediated transactivation. Immunostaining experiments show that hetero-oligomerization does not lead to changes in localization of nuclear p53 demonstrating that delocalization of p53 is not the reason for inactivation. We also show that co-expression of p53 del 1-293 significantly reduces the G1/S arrest by wild-type p53 suggesting that a proper oligomeric form is necessary for wild-type p53-mediated cell cycle arrest. Thus, our work shows that hetero-oligomerization disrupts wild-type p53's biological functions and suggests a mechanism by which p53 mutants may disrupt functions of wild-type p53.

Binding Sites↗

PubMed1998

'Gain of function' phenotype of tumor-derived mutant p53 requires the oligomerization/nonsequence-specific nucleic acid-binding domain.

Tumor-derived p53 mutants can transcriptionally activate a number of promoters of genes involved in cellular proliferation. For this transactivation, mutant p53 does not use the wild-type p53 DNA-binding site, suggesting a mechanism of transactivation that is independent of direct DNA binding. Here we describe our analysis of the domain requirements for mutant p53 to transactivate promoters of the human epidermal growth factor receptor (EGFR), human multiple drug resistance 1 (MDR-1) and human proliferating cell nuclear antigen (PCNA) genes. We also report the identification of a structural domain required for the 'gain of function' property of mutant p53-281G. 'Gain of function' is measured as the tumorigenicity (in nude mice) of 10(3) murine cells expressing mutant p53 constitutively. We have generated internal deletion mutants of p53-281G deleting conserved domains I, II, III, IV and V, individually. We have also generated one deletion mutant eliminating amino acids 100 through 300 that removes four of the five conserved domains (II - V); another mutant, p53-281G del 393-327, deletes the oligomerization and nonsequence-specific nucleic acid-binding domains of p53. For the EGFR and MDR-1 promoters, all these mutants have significantly lower transactivation ability than intact p53-281G. These deletion mutants, however, significantly activated the pCNA promoter, suggesting that the mechanism of transactivation of the PCNA promoter is different from that of the EGFR and MDR-1 promoters. When expressed constitutively in 10(3) cells, p53-281G del 393-327 was found to be defective in inducing tumor formation in nude mice although intact p53-281G was very efficient. Thus, our results suggest that structural domains near the C-terminus are needed for 'gain of function'.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1993

[Architectonics of pulmonary vessels in pulmonary stenosis].

The authors aimed their work on the study of the architecture of pulmonary blood vessels and blood flow via pulmonary vascular network in patients with Fallot malformation. In 34 children with valvular stenosis of a. pulmonalis and in 12 children with Fallot tetralogy they analysed in detail their angiograms, paying attention to evaluation of the architecture of truncus pulmonalis and its branches, the discharging part of the right ventricle, and the state of the arterial phase of the pulmonary vascular network. On the basis of their results the authors explain the preferential blood distribution in Fallot's tetralogy by the displacement of the outflow part of the right ventricle to the right and by a greater amanation angle between the right branch of a.pulmonalis and its truncus. Better routing of blood into the left lung in patients with pulmonary valvular stenosis is according to the authors due to a greater emanation angle between the left branch of a.pulmonaris and its truncus. The authors analyse also the mechanism of formation of poststenotic dilatation of truncus pulmonaris and the left branch of a.pulmonaris in cases of valvular stenosis in infant age. (Fig. 4, Ref. 12.)

Angiocardiography↗

PubMed1991

[Disorders of the cardiovascular system in congenital lentiginosis].

The authors investigated during the last 10 years four patients with lentiginosis and affection of the heart. In none of them the symptoms were complete enough to include it under the leopard syndrome. In two patients the authors found changes in the outflow portion of the right ventricle which was in their opinion caused by hypertrophy of the interventricular septum and musculature of the right ventricle. The authors consider the term lentiginocardiomyopathic syndrome suitable for this rare clinical and genetic entity. The authors check patients with lentiginocardiomyopathic syndrome regularly after 6-month intervals. In two children they recorded progression of the heart disease.

Adolescent↗

PubMed1989

Structural characteristics influencing the carrier function of synthetic branched polypeptides based on poly[Lys-(DL-Ala)3)]backbone.

Effective carrier function of selected representatives of new branched polypeptides covalently coupled with the synthetic monovalent hapten, oxazolone was studied. The effectiveness of oxazolone-synthetic polypeptide conjugates in inducing oxazolone-as well as carrier-specific antibody responses in inbred mice was compared to that of bovine serum albumin (BSA)- and KLH-oxazolone conjugates. The synthetic polypeptides, poly[Lys-(D-Leui-DL-Alam)] (D-LAK), LAK and FAK, as well as the common poly[Lys-(DL-Alam)](AK) core covalently coupled to oxazolone (Ox) induced a T cell-dependent antibody response when repeatedly administered with or without Freund's adjuvant in mice. This was evidenced by: the increasing titer of oxazolone-specific IgG during the course of the memory response; the appearance of all IgG subclasses; the effective oxazolone-specific priming by the conjugates; and the induction of an intense oxazolone- and carrier-specific DTH reaction. Although the oxazolone-specific antibody response was 10-100 times lower than that induced by KLH- or BSA-oxazolone conjugates, it was accompanied by a lower level or no detectable carrier-specific antibody response despite an effective carrier-specific T cell-mediated response. Significant differences were observed between the effectiveness of synthetic polypeptides used as carrier: highest oxazolone-specific antibody titers were observed using the AK, LAK and FAK conjugates. The intensity and specificity of the DTH reaction and antibody response induced by the carrier-oxazolone conjugates suggested that the distinct effectiveness of L- and D-amino acid-containing conjugates (LAK vs D-LAK and FAK vs D-FAK) was dependent on altered B cell recognition of the haptenic group. Circular dichroism (CD) spectra indicating different local orientation of oxazolone, when coupled to L or D side chain-terminating amino acids, support this suggestion.

Amino Acids↗

PubMed1989

[Noninvasive imaging methods and angiography in the diagnosis of chronic viscero-visceral arterial collateral circulation in stenosis of the celiac trunk].

Stenosis or even occlusion of truncus coeliacus represents the most frequent cause in the development of collateral blood circulation with caudiocranial flow through extended pancreatic-duodenal arcades. In a group of 32 patients with such mesenteric-coeliacal collateral circulation their arteriographic picture was evaluated. The authors evaluated differences and specific diagnostic contribution of individual visualization methods for demonstration of arteries. The non-invasive visualization methods are of exceptional contribution in the examination of abdominoretroperitoneal region by considerably decreasing the needs of invasive angiographic examination of catheterization technique. This leads to a decrease in the number of diagnosed chronically developed viscerovisceral arterial collateral circulations of various etiologies. Ultrasonography and computer tomography well depicts morphological changes in the aorta diameter as well as unpaired visceral arteries in the segment of their branching. The viscerovisceral arterial collateral circulations, however, may not be detected or at least not to a sufficient degree. They are represented in detail in the whole course only by selective arteriography. The authors draw attention to supplementary role of arteriography within the framework of non-invasive visualization methods.

Adult↗

PubMed1986