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Biomedical subjects

A Fekete

Publications and source records attributed to A Fekete.

At least 37 records · Page 2Linked to original sources
PubMed1990

Preliminary development of a diagnostic test for Brucella using polymerase chain reaction.

A highly sensitive and specific diagnostic test for Brucella based on polymerase chain reaction is under development in our laboratory. A commercially available PCR kit was used to create primers that allowed the amplification of a 635 bp fragment of a 43 kDa outer membrane protein gene from Brucella abortus strain 19. We successfully amplified the cloned gene present in the pMS64 plasmid and genomic Brucella S19 DNA. The amplified DNA was easily detected by agarose gel electrophoresis. Using both the pMS64 plasmid and Br. abortus S19 purified DNA as template each component of the PCR reaction was adjusted for the optimum amplification of the DNA sequence. Optimum specific amplification resulted when the primer annealing temperature was 60 degrees C. The gene fragment was amplifiable in 25 different Brucella species and strains. To test the specificity of the reaction, DNA extracted from 17 micro-organisms possibly associated with cattle were tested. No amplification was observed. The sensitivity of the reaction was determined with different concentrations of genomic Brucella strain 19 DNA. As little as 0.1 pg DNA (less than 100 brucella cells) could be detected. The specificity and sensitivity of PCR combined with its simplicity and speed suggests the potential of this technique for routine diagnosis of brucellosis.

Animals↗
PubMed1989

Action spectra for photoinduced inactivation of bacteriophage T7 sensitized by 8-methoxypsoralen and angelicin.

The action spectrum (240-300 nm) for photoinactivation of unsensitized phage T7 and the action spectra (310-380 nm) for photoinactivation of phage T7 sensitized with 8-methoxypsoralen (8-MOP) and angelicin were measured by an automated method. For unsensitized phage T7 the action spectrum is in good agreement with the absorption spectrum. For sensitization with angelicin the action spectrum is similar to the absorption spectrum, but for sensitization with 8-MOP the spectra are different. The agreement between the T7 absorption and action spectra in the far-UV region is due to photodamage of DNA, leading to phage inactivation. The similarity in the action and absorption spectra in the near-UV region for sensitization with angelicin seems to be in accordance with the monofunctional photobinding of angelicin to DNA. The action spectrum for sensitization with 8-MOP has a maximum at about 320 nm and this suggests that, in addition to the monoadducts, the biadducts play a role in the inactivation of phage T7. Taking the number of bound furocoumarin molecules into consideration, the quantum efficiencies were estimated. Furocoumarin increases the quantum efficiency in the near-UV region and the values are similar to those obtained in far-UV light without psoralens.

Densitometry↗
PubMed1989

Genotoxicity testing: phage T7 inactivation test of various furan and arenofuran derivatives.

The genotoxic activities of 28 furan and arenofuran derivatives were tested by the phage T7-inactivation test. The genotoxic activity of the compounds was characterized quantitatively. All the compounds studied have pronounced genotoxic activities in our system. Empirical rules relating structure to genotoxic activity were found. Data obtained with our system were compared with the results of other biological systems (Salmonella assay, SOS Chromotest, CHO/HGPRT, gene amplification) in the case of some compounds included as references.

Animals↗
PubMed1984

Improving techniques for clonogenic assays.

A serum-free medium has been developed which supports colony formation by cells from several human tumor cell lines, one colon adenocarcinoma (WiDr) and four melanoma (Me43, Me85, MP6, MeIuso). This medium consists of a 1:1 mixture of an enriched Dulbecco's modified Eagle's medium (EMED) and a modified Ham's F-12 nutrient mixture (FMED) supplemented with 0.9% methylcellulose, 1% bovine serum albumin, 80 micrograms/ml human transferrin, 3 micrograms/ml insulin, 2.8 micrograms/ml linoleic acid, 2.6 micrograms/ml cholesterol, 20 microM ethanolamine, and trace elements. Colony formation by WiDr cells is linear with the numbers of cells plated, having a plating efficiency (PE) of 34%, as compared to 26% in serum-containing medium. Two of the melanoma cell lines. MP6 and MeIuso, exhibit linear relationships between colony numbers and cell concentration with PEs of 21% and 70% respectively. Colony formation by the other two melanoma cell lines appears to be nonlinear. This work represents a step toward standardizing culture conditions for human tumor clonogenic cell assays.

Adenocarcinoma↗
PubMed1982

Temperature dependent structural changes of intraphage T7 DNA.

The phenomena connected with the first phase transition step of the native T7 phage at 40 degrees-65 degrees C have been studied using various methods. In this temperature range a) the optical melting curve shows an absorption decrease, b) the maximum of the small-angle X-ray scattering characteristic for DNA packing disappears, c) there is a drop of biological activity and d) there are changes in the structure of the difference absorption spectra of native phages versus isolated DNA. All data are interpreted assuming a structural change of the DNA due to the release of its protein coat towards the end of the first phase transition step (at 60 degrees-65 degrees C in the case of M9 buffer). Above this temperature the intraphage DNA packing appears to be destroyed and the DNA structure seems to be similar to that in DNA solution.

DNA, Viral↗
PubMed1978

Effect of antidiuretic hormone and indomethacin on intrarenal microsphere distribution.

The purpose of the present study was to reexamine the effect of antidiuretic hormone (ADH) and indomethacin (IM) on intrarenal blood flow distribution by applying the microsphere technique to trained consciuous dogs. ADH and IM were given separately and jointly during maximal water diuresis. ADH in itself caused moderate antidiuresis and marked natriuresis. Although IM by itself had no significant effect on urinary osmotic concentration or solute excretion it greatly enhanced the antidiuretic effect of ADH and abolished its natriuretic effect. Intrarenal blood flow distribution remained unchanged when ADH and IM were given separately but it was shifted toward the inner cortex when the drugs were administered simultaneously. Furthermore, transition from spontaneous antidiuresis to maximal water diuresis did not alter intrarenal blood flow distribution. The results indicate that ADH induced antidiuresis is dissociated from changes in intracortical blood flow distribution. However, the possibility that IM enhancement of ADH mediated antidiuresis is at least in part mediated by intrarenal hemodynamic changes cannot be excluded.

Animals↗
PubMed1975

Experimental renal hypertension in rats.

The present study has been concerned with blood pressure, renal functions and the microscopic changes of the kidney during permanent hypertension induced by unilateral ligation of the renal artery.

Animals↗
PubMed1975

Renal function in rats after unilateral ligation of renal artery.

As we reported earlier unilateral renal artery ligation is followed by a permanent hypertension that is accompanied by marked changes in renal function and in water components. In order to see when these characteristic changes take place we started our observations immediately after renal artery occlusion and finished them at the 3rd week. Rats were put into metabolic cages and several 24-hr urine samples were collected to serve as control values. Then the left renal artery was ligated and in the following 3 weeks observations were continued using also a parallel control group. The experiments ended with the determination of mean arterial pressure. We found that already within 24 hrs following unilateral renal artery ligation there are marked alterations in renal functional parameters that become even more significant with the passing of time. These changes are probably due to a promptly developing hyperfunction and hypertrophy of the contralateral kidney.

Animals↗