PubMed Health⌕ Search

Biomedical subjects

J Gróf

Publications and source records attributed to J Gróf.

At least 37 records · Page 2Linked to original sources
PubMed1982

Intermediate molecular weight substances in sera of psoriatic patients.

In the experiments presented here, serum samples were collected both from psoriatic (PS) (n = 8) and non-psoriatic (NPS) patients (n = 8) and were analyzed by the combination of fractional precipitation (80% ethanol, pH 2) and gel filtration techniques as well as by chemical methods. It was demonstrated that, in comparison to the non psoriatic samples, concentration of the free alfa-amino group bearing and the Lowry positive components as well as total carbohydrate content was significantly elevated in the acidic ethanol soluble serum fraction of psoriatic samples. In psoriasis, the quantity of serum components with UV light absorbing capability at 206 nm, and with a molecular mass between 0.3 and 5.0 KD (estimated by chromatographic criteria) also was elevated in one of the fractions obtained by Sephadex SG-25 chromatography. Results presented in this paper indicate, that psoriasis is accompanied by changes in quality and in quantity of middle size molecular weight serum components with chemical properties suggesting their peptide--and/or glycopeptide-like character.

Chromatography, Gel↗
PubMed1981

Many hitherto unknown peptides are principal constituents of uremic "middle molecules".

The aim of the present investigation was to collect information on the molecular composition of uremic "middle molecules," the 500-5000 molecular-mass serum constituents assumed to be involved in the molecular etiology of uremic intoxication. For this purpose, three fractions of serum containing such molecules were separated by cation-exchange column chromatography. These fractions absorb at 240 nm and are characteristically increased in chronic uremia. By one-dimensional paper chromatography of these fractions it was demonstrated that each could be resolved into at least seven (altogether, 21) ninhydrin-positive subfractions. These, like the original fractions, yielded amino acids on acid hydrolysis. The qualitative amino acid composition of the subfractions differed substantially, both from each other and from that of 31 known peptides with which they were compared. We conclude that hitherto unknown peptides with only limited diffusibility through hemodialysis membranes constitute the main bulk of uremic middle molecules.

Amino Acids↗
PubMed1981

Proliferation related peptides in quiescent and regenerating rat liver.

Aqueous extracts of resting (C) and 30 h regenerating (P) rat livers were partially purified by a combination of ion exchange-, Sephadex- and paper chromatographic techniques. It was demonstrated that a limited number of the semipurified chromatographic fractions inhibited or stimulated both DNA synthesis and cell proliferation, the effect being partially determined by C or P liver origin of the fractions. It was also shown that biological activities were mediated by hepatic peptides of middle molecular size in the semipurified fractions. It is suggested that regulation of hepatocyte proliferation might be under a dual control operating through an interplay of stimulatory and inhibitory peptides, the final outcome determined by their interaction.

Animals↗
PubMed1977

Urea as a selective inhibitor of argininosuccinate lyase.

The effect of urea on various ornithine cycle enzymes has been investigated. It was demonstrated that argininosuccinate lyase was the only ornithine cycle enzyme inhibited by urea in a competitive manner. Based on the data presented the possible role of urea in maintaining a physiological range of intracellular and extracellular urea concentration by controlling hepatic ureogenesis was discussed.

Animals↗
PubMed1977

Non diffusible toxic polypeptides in uraemic sera: a new group of uraemic toxins.

The composition and toxicity of polypeptides prepared from normal and uraemic sera by the combination of Dowex and Sephadex column chromatography have been studied. Significant changes in composition associated with an increased toxicity and decreased diffusibility of peptides (Mwt, 1800--2500 D) isolated from uraemic sera were detected. Due to their moderate of high toxicity as well as their poor or non-diffusibility, these uraemic polypeptides are proposed to be regarded as a new group of uraemic toxins.

Humans↗
PubMedDate not supplied

Possible role of peptides derived from otosclerotic bone in the mechanism of sensorineural hearing loss.

Otosclerotic stapes footplates, superstructures and temporal cortical bones were extracted with 0.25 M guanidine X HCl 0.5 M EDTA (pH 7.4) solution. The extracted non-collagenous peptides/proteins were separated chromatographically on a Sephadex G-25 microcolumn. The peptide composition of the bone samples were compared by capillary analytical isotachophoresis (ITP) in the molecular mass range 0.3-5 kD. The otosclerotic stapes footplate contained 13 ITP subfractions, while the stapes superstructures and cortical bone contained only 9 and 10, respectively. An otosclerosis-specific ITP subfraction was also detected in the stapes footplate, but not in the stapes superstructure or cortical bone. This subfraction was previously demonstrated in the otosclerotic perilymph as well. Four ITP subfractions occurred common in the otosclerotic stapes footplate, the superstructure and the cortical bone. Two of these common subfractions were not found in the cortical bone peptide extract, but all of them revealed higher than normal levels in the otosclerotic perilymph.

Chromatography, Gel↗
PubMedDate not supplied

Peptides of the otosclerotic perilymph examined by analytical isotachophoresis.

Perilymphs of normal and otosclerotic origin were separated chromatographically on a Sephadex G-25 microcolumn. Peptide composition of the perilymphs was compared by capillary analytical isotachophoresis in the molecular mass range 0.3-5 kD. Otosclerotic perilymph samples contain a heterogeneous, UV-absorbing peptide subfraction which is not detected in the normal perilymph. Normal and otosclerotic perilymph, furthermore, contain four common subfractions detected in twice the normal concentration in the otosclerotic perilymph. These ITP subfractions are degraded during acid hydrolysis (6 M HCI). On the contrary, otosclerosis is a deficient state compared with the normal, as the number of peptides or oligoglycopeptides is twice as high in normal as in otosclerotic perilymph, beside the otosclerosis specific peptides.

Electrophoresis↗