The "VEB Filmfabrik Wolfen" offers a textile material for sale, which is well suited for manufacturing of ultrathin reinforced polyacrylamide gels. In contrast to the glass- or polyester-stabilized gels such fabric-reinforced gels allow diffusion- or electroblotting methods. First experiences with ultrathin SDS- and IEF-gels, manufactured using this new supporting material are represented.
The positivepaper DDP 111 manufactured in the Fotopapierwerk Dresden is presented. It allows to make copies (1:1) of electrophoreses. Independently of the used staining procedure it is a simple, quickly and cameraless possibly to obtain reproductions with a high quality. The DDP 111 allows to resolve the problem of documentation of electropherograms (especially of wet flat gels) and to build up collections and data files respectively.
On the hand of a small number of patients with coronary bypasses the influence of heart-lung-machine-operations on the neopterin level in blood, generally used for the detection of rejected heart transplants, is investigated. The results suggest, that the Neopterin level is not affected by the surgical attempt.
After isoelectric focusing of proteins of human pure pancreatic juice following digestive enzymes and zymogens were identified by substrate specific detection methods: in the anodic range trypsinogen 1, and acidic form of proelastase and procarboxypeptidase A; in the pH--range of 5.0-6.0 a trypsinogen--like protein and the secretory trypsin inhibitor; in the pH--range of 6.0-7.0 one form of each of procarboxypeptidase B, trypsinogen 2, lipase, chymotrypsinogen and two forms of alpha-amylase and in the cathodic range an activated form of procarboxypeptidase B, one form of prophospholipase A2 and an additional form of proelastase. In order to characterize glycoproteins the IEF separated pancreatic proteins were transferred onto nitrocellulose membranes. Using the periodic acid/Schiff's reagent (PAS) procedure five PAS-positive proteins (pl s 4.5; 6.0; 6.6; 6.9 and 7.3) were detected. Three Con A-binding proteins (pl s 6.0; 6.6 and 6.9) were identified by incubating the blot in Con A followed by peroxidase and o-phenylendiamin as a chromogenic peroxidase substrat.
Three methods of the determination of insulin in serum were optimized in order to determine low concentrations of this analyte reliably (Method I: enzymatic after acidic hydrolysis of inulin; Method II: by anthrone/sulfuric acid reagent; Method III: by cysteine/tryptophan reagent). The interfering reaction of glucose in the methods I and II was avoided by the preincubation of samples with glucose oxidase/catalase reagent. The detection limit of all three methods was below 5 mg/l and the within-run precision amounted to values below 5%. Method I and II gave identical results. In comparison with these two methods, method III resulted in inulin values by about 8% lower, because inulin, depending on the lot used, contained alkali-labile fractions which were destroyed during the sample preparation. Method II is recommended for routine measurements because of its an analytical reliability and its cost-effectiveness.
A solid-phase enzyme immunoassay, a radioimmunoassay and the passive hemagglutination were tested for the determination of antithyroglobulin autoantibodies. The antibody-titres detected with these methods showed a good correlation. The sensitivities of the solid-phase immunoassays are four times higher than the sensitivity of the passive hemagglutination. For the diagnosis of thyroid autoimmune diseases the enzyme immunoassay.
Filterability measurements have been used widely in medical research and clinical practice to characterize erythrocyte deformability. In the present paper the influence of white blood cells (WBC) on the of filterability indices is investigated and discussed. We found for two gravity filtration systems using cellulose filters and concentrated erythrocyte suspensions sensitivities of their filterability indices of 1% per 100 WBC/microliters (initial) filtration rate measurement) and 3% per 100 WBC/microliters (hemofiltrometer). The necessity, advantages and disadvantages of additional methods for WBC removal are discussed in comparison to nuclepore filtration systems with sensitivities of 5-12% per 100 WBC/microliters. The standardization of residual WBC-count in limits of 500 +/- 300 WBC/microliters at a hematocrit of 60% is proposed.
The degree of nonenzymatic glycation of serum proteins was estimated in 500 nondiabetic subjects and in 124 Type 2 diabetic out-patients. The values were evaluated in relation to a DMF calibration curve, a secondary glycated protein standard and to serum protein concentrations. Neglecting the evaluation with respect to the protein concentration 0.4% of the samples from nondiabetics and 9% from diabetic patients would have been incorrectly interpreted. The fructosamine values from nondiabetic subjects showed a Gaussian distribution. The use of secondary protein standards is a premise to a widespread application of the fructosamine assay in diabetic care. The calibration of such secondary glycated protein standards results in some problems when using DMF protein mixtures as primary standards, because albumin preparations from the same or different suppliers gave variable standardization curves.
The punctates of the biochemical joint function test contain hydroxyethyl starch which disturbs the assay of uronic acid and glucosamine for the estimation of hyaluronate. Therefore hyaluronate (0.03-0.75 g/l) was estimated by precipitation with Alcian blue on cellulose acetate membranes and measuring of the absorbance at 678 nm after dissolution in aqueous SDS (75 g/l). The gel-filtration HPLC separates the high-molecular-mass hyaluronate from low-molecular-mass impurities of biological samples. By comparing with a standard curve (0.5-2.5 g/l hyaluronate) the concentration can be determined. The results obtained by the two methods were significantly correlated (p less than 0.05). The Alcian blue technique is useful for rapid screening, the HPLC technique to confirm these values.
Two modifications of a double antibody enzyme immunoassay for the determination of urinary albumin content are described. The method is simple, rapid and precise and can be carried out in test tubes and on microtiter plates as well. In 1:10 diluted urine samples albumin concentrations of 1.25 to 20 mg/l (corresponding to the normal range) can be determined. For a control sample with 0.3 mg/l albumin the intra- and interassay coefficients of variation were 4.9% (n = 11) and 10.4% (n = 21), respectively, on microtiter plates.
A further investigation of the Arzneibuch (Diagnostic Laboratory Methods) GDR-method for the estimation of N-acetylneuraminic acid was performed. By this was found, that the formation of the dye complex is not still finished after 15 minutes and the reaction product shows an exponential decomposition. The decomposition rate was much greater in the reaction medium than in n-amyl alcohol. By increasing the ferric (III)-chloride concentration the specificity of the method could be essentially improved. With the fivefold ferric (III)-chloride concentration the physiological concentrations of the protein bound monosaccharides of the serum changed the accuracy of the measuring results by less than or equal to 2.0%.
