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Biomedical subjects

A Lengyel

Publications and source records attributed to A Lengyel.

At least 19 recordsLinked to original sources
PubMed2004

Prediction of ozone concentration in ambient air using multivariate methods.

Multivariate statistical methods including pattern recognition (Principal Component Analysis--PCA) and modeling (Multiple Linear Regression--MLR, Partial Least Squares--PLS, as well as Principal Component Regression--PCR) methods were carried out to evaluate the state of ambient air in Miskolc (second largest city in Hungary). Samples were taken from near the ground at a place with an extremely heavy traffic. Although PCA is not able to determine the significance of variables, it can uncover their similarities and classify the cases. PCA revealed that it is worth to separate day and night data because different factors influence the ozone concentrations during all day. Ozone concentration was modeled by MLR and PCR with the same efficiency if the conditions of meteorological parameters were not changed (i.e. morning and afternoon). Without night data, PCR and PLS suggest that the main process is not a photochemical but a chemical one.

Air↗
PubMed2001

Alternate adenovirus type-pairs for a possible circumvention of host immune response to recombinant adenovirus vectors.

With the help of monoclonal antibodies the existence of at least 18 different earlier not known intertype (IT) specific epitopes were demonstrated in different numbers and combinations on the hexons of different adenovirus serotypes. The IT specific epitopes play an important role in the experimental gene therapy and in the recombinant adenovirus vaccination because of the harmful immune response of the recipient organisms directed against the many different epitopes of the adenovirus vector. For the elimination of harmful effect the authors suggest the use of multiple vectors, each prepared from different adenovirus serotypes showing the loosest antigenic relationship to each other. The vectors would be used sequentially when second or multiple administration is needed. For this purpose the authors determined and described 31 such adenovirus type-pairs, which are probably the best alternates for sequential use in experimental gene therapy.

Adenoviruses, Human↗
PubMed1999

Taguchi optimisation of ELISA procedures.

We propose a new method in the field of ELISA optimization using an experimental design called the Taguchi method. This can be used to compare the net effects of different conditions which can be both qualitative and quantitative in nature. The method reduces the effects of the interactions of the optimized variables making it possible to access the optimum conditions even in cases where there are large interactions between the variables of the assay. Furthermore, the proposed special assignment of factors makes it possible to calculate the biochemical parameters of the ELISA procedure carried out under optimum conditions. Thus, the calibration curve, the sensitivity of the optimum assay, the intra-assay and inter-assay variability can be estimated. The method is fast, accessing the results in one step, compared to the traditional, time-consuming 'one-step-at-a-time' method. We exemplify the procedure with a method to optimize the detection of ScFv (single chain fragment of variable) phages by ELISA. All the necessary calculations can be carried out by a spreadsheet program without any special statistical knowledge.

Analysis of Variance↗
PubMed1998

Characterization of intertype specific epitopes on adenovirus hexons.

The specification and differentiation of eighteen intertype specific (IT) epitopes of adenovirus hexons defined by monoclonal antibodies are given by two groups of hexon types: on which they are and on which they are not present. The close specificity relationship among some groups of epitopes determined by pairwise analysis according to their presence on the hexon types indicate that they could be continuous (sequential), overlapping or discontinuous (topographic) epitopes. Based on the identification of the hydrophilic regions and the localization of beta-turns sixteen IT epitope sites were predicted on human adenovirus (HAdV) type 2 and nineteen on HAdV-41 hexon's amino acid (aa) sequences beside the type and genus specific ones. The 16 predicted IT epitopes on HAdV-2 hexon show good coincidency with the 14 IT epitopes demonstrated with monoclonal antibodies (MAbs) on this hexon type. The predicted number of common epitopes between HAdV types 2 and 41 also corresponds well with the eight IT epitopes determined by MAbs, but the 17 predicted non-common epitopes indicate the possibility of the existence of more epitopes on these hexon types. The location of the predicted epitopes of HAdV-2 were determined by alignment of their sequence numbers on the three dimensional ribbon representation of the hexon subunit. Most of the predicted IT epitopes were found between the type and genus specific epitopes i.e. in the "upper" regions of pedestal domains P1 and P2 orientated toward the virion surface and in the "lower" part of loop 1 region orientated inside the virion. Two peptides representing potential IT epitopes were synthesized corresponding to residues 309-320 from the "lower" part of loop 1 and 399-408 from the "upper" part of P1 region of HAdV-2 hexon. Antibodies raised against the peptide-carrier conjugates recognized different purified native hexon types in ELISA.

Adenoviruses, Human↗
PubMed1998

Interrelationship of viruses and cells. The cytopathic property of adenoviruses.

The application of in vitro cell cultures in virus research has a great importance in studies on the interaction between virus and cell. A great number of the viruses causes characteristic degeneration in the infected cells, well visible in the light-microscope, and due to their cytopathic effect the existence of viruses became directly detectable. Based on characteristic changes even the serological type of virus can be determined in some cases. Thus the multilateral examination of the interaction between virus and host cell has immense importance both in virus research and in therapy.

Adenoviruses, Human↗
PubMed1996

Characterization of adenovirus hexons by their epitope composition.

For the investigation of epitope composition of different adenovirus hexon types sixty-one mouse ascitic fluids containing monoclonal antibodies (MAbs) developed in three different panels were used. The distinction and marking of the different epitopes recognized by the MAbs were carried out by the determination of the composite cross-reactivity pattern, the titer and the correlation coefficient of all the 61 MAbs with 21 different hexon types representing all the six human subgenera, as well as different bovine and simian adenoviruses. The distinct epitopes were marked by two numbers referring the homologous hexon type to which the MAbs were directed and the serial number of the epitope specified by the different members of the given panel of the MAbs. The three panels of MAbs recognized 22 epitopes on the 21 hexon types among them a genus and three type specific ones and 18 different bi- and multilateral intertype (IT) specific epitopes that grouped adenoviruses within the genus, independently from the subgenus they belong to. Considering that the type specific epitope could be present only on the homologous hexon type, the largest number of the different epitopes distinguishable by the MAbs used could be 20 on the homologous hexon and 19 on the heterologous ones. It was found that the total number of IT specific epitopes on the hexons varied between 2 and 18. The distribution of the distinct specific epitopes on the different hexon types was different, as expected. The antigenic structure of the individual hexon types were characterized by the determination of their IT specific epitope spectrum. By pairwise analysis ten human hexon types formed three epitope clusters (types 4 and 19; types 8, 9, 9/13 and 10; as well as all types of subgenus C) showing identical epitope spectra. No clustering was found with human type 7, 12, 13, 18, 26, 27, 35 and 41, as well as with bovine and simian adenovirus hexons studied. However, they displayed a closer or looser antigenic relationship among each other and to members of the epitope clusters. The degree of antigenic relationship could be expressed by the similarity/dissimilarity percentage calculated from the number of the identical and different epitopes present on any two given hexon types.

Adenoviruses, Human↗
PubMed1996

Intertype specific epitopes on the hexons of adenovirus types 1, 2, 5 and 6.

The intertype specificities of the epitopes present on the surface of the hexon types belonging to human adenovirus (Ad h) subgenus C were studied. The reactivity pattern (RP) and the titres of ascitic fluids containing monoclonal antibodies (MAbs) were determined in ELISA. From three panels of MAbs 38 directed against Ad h1, 17 directed against Ad h 35 and 6 MAbs directed against bovine adenovirus type 2 were studied. Twelve of the MAbs proved to be genus or type specific. The rest of the MAbs showed numerous intertype specific RPs in different combinations on the different hexon types according to previous experiments with purified hexons of different Ad h subgenera and animal serotypes. With hexon types 1, 2, 5 and 6 of subgenus C all intertype specific MAbs gave identical RPs and the titres of the individual MAbs with all the four hexon types were generally high, and the most frequently found titres were evenly distributed among them. These results indicate the presence of numerous different intertype specific epitopes on the hexons of subgenus C in identical combination on the four hexon types.

Adenoviruses, Human↗
PubMed1995

Antigenic homogeneity among the adenovirus hexon types of subgenus C.

Antigenic relationships of hexons of human adenovirus (Ad h) types 1, 2, 5 and 6 of subgenus C were studied with 61 monoclonal antibodies (MAbs) raised against human Ad h1, Ad h35 and bovine adenovirus 2. The reactivity pattern (RP) and the titers of the MAbs were determined in indirect ELISA. In previous experiments with hexons of different subgenera 49 MAbs displayed numerous different intertype specificities besides genus specific and type specific ones. With the four hexon types of subgenus C all MAbs gave identical RPs except the type specific ones. Data reveal the existence of a remarkable homogeneity in the antigenic structure among the hexon types of subgenus C defined by the presence of identical or closely related intertype specific epitopes on the surface of the hexons. The possible significance of the results in the experimental gene therapy is discussed.

Adenoviruses, Human↗
PubMed1995

Diversity in the antigenic structure of different hexon types among the members of adenovirus subgenus D.

Antigenic relationships of human adenovirus (Ad h) hexon types: 8, 9, 10, 13, 19, 26, 27 and intermediate type 9/13 (I13), belonging to subgenus D were studied with 61 hybridoma ascitic fluids containing monoclonal antibodies (MAbs). The MAbs were produced in three different panels directed against Ad h1, Ad h35, and bovine Ad type 2. The reactivity pattern (RP) and the degree of cross-reactivity (CR) of the MAbs were determined in indirect ELISA. By the 61 MAbs 8 different RPs could be distinguished. The distinct RPs of hexon types of 8, 9, 10, I13 and 19 were identical or nearly identical and the occurrence of the different eight RPs were based mainly on the combinations of positive or negative reactions of different MAbs with the hexon prototypes 13, 26 and 27. According to the different RPs and to the number of reacting and non-reacting MAbs with the different hexon types as well as on the base of the degree of CR three groups of hexon types with diverse antigenic structure could be distinguished. These data revealed the existence of remarkable diversity in the antigenic structure between type 27 and types 8, 9, 10, I13 and 19, as well as an intermediate position of prototypes 13 and 26.

Adenoviridae↗
PubMed1993

Latex agglutination and adenoviruses. II. Detection of antigens.

Latex particles were coated with different monoclonal antibodies (MAbs) reacting with different epitopes of the hexons of adenovirus (AV) type h1 and h35. The coated particles were tested with the purified hexon of 22 different mammalian AV types and were agglutinated by the respective hexon antigen(s) with high specificity. The sensitivity of the reaction was influenced by the amount of MAb adsorbed to latex particles. The latex, coated with a MAb of genus specific reactivity can be a valuable tool in the rapid immunodiagnosis of adenovirus infections.

Adenoviruses, Human↗
PubMed1992

Antigenic relationships among the members of adenovirus subgenera determined by monoclonal antibodies.

Epitope composition of human adenovirus (AV) serotype 13 (subgenus A), 19, 26 and 27 (subgenus D), as well as 41 (subgenus F) was studied with 23 selected monoclonal antibodies (MAbs) raised against different hexon types. With the help of three panels of MAbs great differences were shown in the epitope structure of subgenus D hexons. Comparing two AV13 strain hexons (a prototype strain and an intermediate strain), it was shown that the epitopes recognized by the MAbs were present in different combinations even on strains of the same serotype. Therefore the epitope composition of the subgenus D hexons seems to be heterogeneous.

Adenoviridae↗