Jan Rosmus

Thin layer chromatography of dansyl amino acid derivatives

Abstract Dansyl derivatives of amino acids can be easily separated by thin layer chromatography. Dansyl derivatives of all naturally occurring amino acids can be identified in two-dimensional chromatographic separations. For their orientation in an unknown mixture the following combination of solvents was most useful on Dilicagel G: 1st run: benzene—pyridine—acetic acid (16:4:1), 2nd run: chloroform—benzyl alcohol—acetic acid (70:30:3).

Rapid determination of melamine and cyanuric acid in milk powder using direct analysis in real time-time-of-flight mass spectrometry

The use of fast semi-automated method employing direct analysis in real time (DART) ion source coupled to time-of-flight mass spectrometry (TOFMS) for analysis of melamine (MEL) and cyanuric acid (CYA) in milk powder and milk based products has been demonstrated in this study. Simple sample extraction procedure employing methanol-5% aqueous formic acid mixture, which enabled disruption of melamine-cyanurate complex, was followed by direct, high-throughput (30s per run) examination of sample extracts spread on a glass rod by mass spectrometry under ambient conditions, without any prior chromatographic separation. After optimization of instrument parameter settings, limits of detection (LODs) 170 and 450microgkg(-1) were achieved for MEL and CYA, respectively. In the final phase of study, the possibility of minimizing spectral interference, thus improving method performance characteristics through the use of ultrahigh resolving power offered by Orbitrap based mass analyzer is demonstrated.

Aging of the connective tissue: Collagen cross linking in animals of different species and equal age

Abstract The rate of collagen cross-linking has been proved to be independent on the expected lifespan of the animal. The authors conclude that cross-linking of collagen in old age is a result of diverse deteriorating processes occurring with time in the living body, rather than one of the presumably multiple causes of aging. It seems likely that one of the decisive aspects is the surrounding temperature in cold blooded vertebrates or the body temperature in homoiothermic animals. It has been verified that in cold blooded vertebrates the final degree of cross-linking is considerably lower compared to homoiotherms.

The effect of food deprivation on collagen accumulation

Abstract It has been reported that there is a distinct increase in collagen concentration in lungs, liver, and kidneys in rats beyond 20 months of age. In organs investigated no distinct organ specificity was observed. In undernourished animals which were kept on 50 per cent food intake the same phenomenon was delayed until the age of 32 months. The starting point of collagen accumulation was followed by an evident increase in the mortality rate. Simultaneously with the collagen accumulation and the increase in the mortality rate. Simultaneously with the overall body weight in both controls and undernourished rats was noted. The increase in collagen concentration was paralleled by a decreased water content in tissues under investigation.

Column chromatographic separation of dansyl amino acids.

Abstract A column chromatographic separation of dansyl amino acids is described in which polyamide is used as the sorbent and three systems with different benzene-acetic acid ratios are used as the eluent. The separation method offers good possibilities for quantitative determinations. Additional correlations can be made by using the same material for identifying an unknown amino acid. The column effluent is monitored by an adapted Farrand spectrofluorimeter equipped with a flow-through cell and a reduced chart speed gear box.

AGING OF CONNECTIVE TISSUE. THE EFFECT OF DIET AND X-IRRADIATION.

Abstract The effects of decreased food intake, of fat rich diet and of X-radiation were studied. Each of these treatment is known to influence collagen maturation in vivo . It was established that undernutrition retards aging of collagen preferentially when applied to young animals. High fat diet was proved to increase collagen stability, presumably by inducing new hydrophobic contacts. The effect of irradiation is strongly dose-dependent and reflects simultaneously occuring polymerization and depolymerization of the structure. In atherogenic diet-fed animals, ionizating radiation has a predominantly polymerizing effect, which appears to be the result of the conversion of hydrophobic contacts in two other types of bonds. On the tissue level it has been observed that high fat diet causes a pronounced accumulation of collagenous stroma in organs which otherwise exhibit low rate of collagen turnover.

Centrifugal chromatography : IV. A simple distributor for centrifugal chromatography☆

Abstract In this paper a simple distributor of the mobile phase for centrifugal paper chromatography is described. This distributor has some advantages over other systems described previously, viz. the more rapid and simple manner in which the mobile phase is fed from the reservoir. Since this device enables the mobile phase to be changed rapidly, it can be used for such types of chromatography where this is necessary, as well as for gradient elution paper chromatography.

Centrifugal chromatography : V. Apparatus for preparative-scale paper chromatography in the centrifugal field☆

Abstract A simple technique and the necessary apparatus for quick preparative-scale paper chromatography is described. In order to reduce the time of separation the principle of centrifugal paper chromatography was used. The device permits a precise and controlled separation of the spotted sample into individual fractions within one-third to one-tenth of the time required for conventional chromatography.

Changes in the collagenous stroma in rat kidney in relation to age

Abstract It has been shown that both increasing age and hypertrophy cause a distinct increase in the collagen proportion in the kidney. However, in both cases the qualitative features of the collagenous stroma differ: while in aging less soluble forms of collagen are present as indicated by polyacrylamide gel electrophoresis, the collagenous stroma of hypertrophied kidneys is formed by rather lightly cross-linked protein. According to the amino acid composition it appears that the collagenous stroma which accumulates in both situations is formed mainly by collagen of the basement membrane. It was observed that the overall proportion of collagenous proteins may rise up to 9·19 μg hypro per 100 mg of organs wet weight without any macroscopic effect in the animal indicating the extent of the renal reserve in rat.

On the presence and localization of an unknown ninhydrin positive compound in ageing collagen

Abstract An unknown, ninhydrine-positive compound has been registered in the collagen molecule. This compound, designated as “X” can be split off by pronase, indicating so its presence in the so-called telopeptides. Compound X is present in three different peptide sequences namely gly.glu.tyr.val-X, glu.gly.gly.tyr.val X and gly.glu.gly.ser.ala. X. As analogous sequences in which X was replaced by lysine were found in the neutral salt soluble collagen whereas those with X were found in insoluble collagen, it seems quite feasible to speculate on the possible character of X as a lysine derivative. The N-terminal analysis showed only one N-terminal in each of the peptides in which X was present. Therefore it does not seem probable that the compound X would perform any kind of branching of the collagen molecule. The presence of peptides with lysine replaced by X in the insoluble collagen seems to indicate the existence of lysine → X conversion as a process connected with the maturation of collagen.