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Biomedical subjects

K Macek

Publications and source records attributed to K Macek.

At least 55 records · Page 3Linked to original sources
PubMed1981

The effect of food restriction and low protein diet upon collagen type I and III ratio in rat skin.

It has been demonstrated that the content of the collagen type I is more affected by both chronic low protein diet feeding and chronic food deprivation (50% food intake) than the content of collagen type III. By introducing these dietary regimes the proportion of collagen type I to collagen type III ratio drops from 2.1 to 1.3 indicating the higher proportion of collagen type III in the skin at the end of the experiment (after 18 months of chronic feeding). It was also observed that the total concentration of hydroxyproline (hyp) in the skin decreases considerably in both food restricted animals and those fed a low protein diet. It is suggested that, under the present experimental conditions, the balance between collagen break-down and synthesis is shifted and, furthermore, that this shift is different for collagen type I and III and results in an altered ratio of these two collagen species in the skin. Refeeding of animals leads to a higher than normal collagen type I to III ratio indicating thus a relatively higher proportion of collagen type I in this tissue.

Animals↗
PubMed1980

Studies on the chemical nature of elastin fluorescence.

Two fluorescent fractions were found in total acid hydrolysate of elastin. The fraction with higher chromatography mobility in isopropyl alcohol/conc. ammonia/water (9 : 1 : 2) was purified by multiple preparative paper chromatography in the same solvent system, and by gel chromatography on Sephadex G-25, ion-exchange chromatography on phosphocellulose and another gel chromatography on Sephadex G-10. The purified material was chromatographically homogeneous, had an ultraviolet absorption maximum at 315 nm and exhibited a strong 320/405 nm fluorescence. 1H- and 13C-NMR spectra were in good agreement with those published previously [6] for pyridinoline, a lysine derived fluorescent compound in collagen. The major part of the fluorescent material present in acid hydrolysate of elastin was always contaminated, even after complex purification procedures. It is concluded that elastin contains several fluorophores, one of which is a cross-linking tricarboxylic amino acid with a pyridinium ring having very probably the structure of 3-(2-amino-2-carboxyethyl)-1-(5-amino-5-carboxy-2-hydroxy-pentyl)-4-(3-amino-3- carboxypropyl)-5-hydroxypyridinium. The position of 2-amino-2-carboxyethyl and 3-amino-3-carboxypropyl residues has not been definitely established and can be interchanged.

Amino Acids↗
PubMed1980

Two-dimensional thin-layer chromatography of Dns-amino acids on reversed-phase silica gel.

Ready-for-use reversed-phase high-performance thin-layer chromatographic plates were used for the separation of Dns-amino acids. The development was performed by using methanol-2% acetic acid (75.25) or methanol-0.01 M Na2HPO4 (75:25). Reversed-phase plates were used also for adsorption chromatography using a non-aqueous solvent system such as benzene-chloroform-acetic acid (50:48:2) or n-heptane-ethyl acetate-acetic acid (65:33:2). Good separations were achieved by using both principles in the two-dimensional arrangement.

Acetates↗
PubMed1980

gamma-Carboxyglutamic acid-containing protein of rat kidney cortex. Changes with high fat diet, and molecular parameters.

It was shown that the level of gamma-carboxyglutamic acid-containing protein is increased in perfused rat kidney after long-term administration (60 and 350 days) of a high-fat diet. No difference was found between the effect of vegetable fat and animal fat. Concomitantly it was shown that the relative molecular weight, N-terminal sequence over four residues, the profile of chymotryptic peptides and the sequence around the two (of the three in total) gamma-carboxyglutamic acid residues (over the span of seven residues) are identical with those found previously in osteocalcin and the gamma-carboxyglutamic acid-containing protein isolated from at least partially calcified connective tissue.

1-Carboxyglutamic Acid↗
PubMed1980

Urinary spermidine levels in cases of carcinoma of the prostate. Preliminary report.

Normal ranges for urinary spermidine have been determined as 0.0 to 1.9 mg per 24 hours. In benign prostatic hyperplasia and urinary infection the urinary spermidine excretion ranges between 1.2 and 2.6 mg/24 hours. Significantly elevated excretion has been noted in 10 patients with prostatic carcinoma (4.5 to 11.4 mg). The high-performance liquid column chromatography was used as the method for separation of urinary polyamines and spermidine determination.

Aged↗
PubMed1979

The presence of gamma-carboxyglutamic acid-containing protein in atheromatous aortae.

It has been established that a gamma-carboxyglutamic acid-containing protein is present in rat aortae after long term atherogenic diet administration. A similar protein was proven to be present in turkey tibial tendons that are predisposed to undergo physiological calcification. The molecular weight and amino acid composition of both proteins were identical. They contained six glutamic acid residues per molecule, three of which were gamma-carboxylated. The proteins studied were also identical in their N-terminal sequence over six residues. This sequence was fully coincident with that published for osteocalcin (Price, P.A., Poser, J.W. and Raman, N. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 3374--3375). In the region corresponding to residues 20--26 in osteocalcin, a single replacement of valine for isoleucine was found in turkey tendon protein. From the physiological point of view it should be mentioned that the level of the gamma-carboxyglutamic acid containing protein in atherogenic diet fet rat aortae exceeds that found normally in bone or in tissues predisposed for physiological calcification.

1-Carboxyglutamic Acid↗
PubMed1979

Ways of collagen separation in pathologically altered tissue.

A system of chromatographic methods using two successive DEAE-cellulose chromatographic steps and two successive separations on Bio-Gel A-1.5 m has been worked out for the separation of individual collagen types. The success of the procedure is based on the preliminary removal of proteoglycans during the first DEAE-cellulose run. Alternatively it is possible to replace chromatographic steps, following the removal of proteoglycans, with fraction precipitation.

Chromatography, Agarose↗