Continuous UV photometric monitoring of the efficiency of hemodialysis.

Process and efficacy of hemodialysis can be readily monitored by continuous measurement and registration of transmittance at 254 nm of the dialysate. An additional advantage of the method is that it can be easily automatized.

Non-collagen proteins of stapedial bone matrix in perilymph of otosclerotic patients.

Non-collagen proteins extracted from the otosclerotic stapes footplate, superstructure and temporal cortical bone were compared with the protein patterns of normal and otosclerotic perilymph by analytical isotachophoresis (ITP). Normal and otosclerotic perilymph yielded basically identical isotachophoretic subfractions. Thirteen subfractions were detected moving as anions at pH 9.6 in the normal perilymph, versus 16 subfractions of similar character in the otosclerotic perilymph. Of these 16 protein subfractions, one (which was not detected in the normal perilymph) could be found in the ITP-gram of the stapes footplate non-collagen proteins, but not of the stapes superstructure or temporal cortical bone. Our results support the concept that protein can enter the inner ear fluid spaces from the otosclerotic bone. The biological significance of these proteins has not yet been clarified.

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.

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.

The role of basic amino acids of the seminal plasma in fertility.

The role of basic amino acids in male infertility is discussed. The changes in the arginine, ornithine and total amino acid concentrations of the seminal plasma in various types of pathospermia are commented upon in the light of published evidence and of the authors' own observations. A recent procedure (CV-technique) introduced by the authors into the routine investigation scheme of infertility is reported. The method detects the arginine-deficient type of pathospermia, thus contributing to the possibility of its selective correction.

Effect of hyperosmolar peritoneal dialysis fluid on the elimination of small- and medium-molecular substances.

The efficiency of peritoneal dialysis by the use of hyperosmolar dialyzing fluid (680 mOsm/1) was studied in 7 patients with chronic renal failure. The results were referred to the control values obtained in the first and in the terminal periods. In the course of treatment by means of the solution of high osmolarity the clearance of small- and medium-molecular substances increased. A significant increase in ultrafiltration was demonstrable. Protein loss and elevation of the blood glucose levels were noted as side-effects.

[Removal of substances with low and medium molecular weight by repeated application of C-DAK-capillary dialysers]. / Die Elimination von Stoffen mit kleinem und mittlerem Molekulargewicht bei wiederholter Verwendung von C-DAK-Kapillardialysatoren.

The capillary dialysator type C-DAK (Cordis Dow Mod. 4) can according to the regeneration method described be used three times as valid membrane for the elimination of the small as well as of the medium-sized molecules from the serum in the same patient.

Effect of immobilization by plastering on the level of various energy metabolites in skeletal muscle.

The effect of 1 to 6-week limb immobilization by plaster fixation and the resulting skeletal muscle inactivity-atrophy was studied by analysing isotachophoretically the ATP, ADP, AMP, CrP, NAD+ and Pi content of the slow-oxidative soleus, and the fast-glycolytic gastrocnemius muscle of the rabbit. ATP and CrP levels were higher in the glycolytic while NAD+ content was higher in the oxidative skeletal muscle under normal conditions. Energy homeostasis of the muscles disturbed during the first week of immobilization, and subsequently it is adapted to the inactivity by reaching a new steady state at lower energy levels. This new level as characterized by the high energy phosphate content shows no significant difference between the two muscle types.

Molecular weight distribution, diffusibility and comparability of middle molecular fractions prepared from normal and uremic sera by different fractionation procedures.

Sephadex G-25 (SG-25) chromatography of normal and uremic (U) sera yielded three (A, B, C) optically active (280 nm) fractions. Only fraction B disclosed a substantial increase in uremia that could not be counteracted by routine hemodialysis. Although middle molecules (MM) might be included in all SG-25 fractions (B greater than C greater than A), none of them was exclusively composed of MM. Solutes in U fraction B and C were found to be (a) heat stable; (b) soluble in ethanol; (c) diffusible through a Visking membrane, and (d) adsorbed by activated charcoal. Solutes in U fraction B and C and those in a toxic ethanol U serum extract could be partially or entirely recovered in the same Dowex fractions which were obtained by Dowex chromatography of native U sera. Methodical pitfalls leading to misinterpretation of molecular weight data obtained by SG chromatography and to erroneous classification of MM are also thoroughly discussed in this paper.

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.

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.

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.

Cytostatic peptide isolation from culture media of mouse peritoneal exudate cells.

It was found that the supernatant of mouse PEC culture medium (MCM) (both resident and casein-elicited cells) has an inhibitory effect in vitro on the incorporation of [3H]TdR into DNA of mouse spleen cells. The inhibitory effect in the MCM appears in the first 24 hr and also reaches its maximum value within this time. The inhibitory effect of this factor could not be demonstrated in the extract of freshly harvested M phi cells. The factors responsible for inhibition proved to be heat stable at 80 degrees C for longer than 30 min. Following heat treatment, the crude extract was separated into four fractions absorbing uv light at 280 nm using Sephadex G-25 column chromatography, and the most potent biologically active inhibitory factor was eluted in the last fraction. This fraction could also be obtained with a more effective permeation volume using Trysacryl GF 05 gel chromatography, and the active B fraction from this chromatography could be separated into four subfractions by isotachophoresis (ITP). The active fraction, which was obtained by Trysacryl GF 05 gel chromatography and further separated by ITP, was found to be highly inhibitory. It contained a peptide-like substance with a molecular mass of approximately 2.0 kDa and had an anionic character at pH 4.0. The inhibitory effect of MCM cannot be influenced either by inhibitory compounds of protein synthesis or by proteolysis blocking agents. Furthermore, the inhibitory effect is shown to be reversible and is more pronounced on B cells than on T lymphocytes.