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Biomedical subjects

W Vogt

Publications and source records attributed to W Vogt.

At least 109 records · Page 6Linked to original sources
PubMed1982

Role of histamine in the spasmogenic effect of the complement peptides C3a and C5a-desArg (classical anaphylatoxin).

The role of endogenous histamine in the spasmogenic effect of the complement-derived peptides C3a and C5a-desArg (isolated from yeast-activated hog serum) was studied in strips of terminal guinea-pig ileum. The effect of C3a is apparently histamine-independent; it neither induces histamine release from the test organ nor is its spasmogenic action inhibited by the H1-antihistaminics pheniramine and triprolidine, used in concentrations effective against histamine. However, endogenous histamine may be involved in the spasmogenic effect of C5a-desArg; when applied repeatedly C5a-desArg induces histamine release during its first and second application. Furthermore, both H1-antihistaminics inhibited C5a-desArg-induced contractions considerably, though less efficiently than those of added histamine.

Anaphylatoxins↗
PubMed1982

Factors in cobra venoms affecting the complement system.

Three constituents of cobra venoms are known to interact with complement: the "cobra venom factor" (CVF), a high-molecular-weight factor (H-CoF), and the "cobra inhibitor" (CI). CVF and CI act by forming complexes with certain complement components. In doing so, CVF replaces an endogenous component, C3b, and hence activates the alternative pathway and leads to C3 (and C5) consumption. In contrast, CI competes with essential complex formations of endogenous components and thus inhibits various reactions. Both, CVF and CI, are useful tools to study the biochemistry of complement and its pathophysiological involvements. The effect of H-CoF on complement has not yet been studied in detail.

Complement System Proteins↗
PubMed1982

Activation of the classical complement pathway by a polysaccharide from sugar cane.

The effects of an immunostimulating polysaccharide, Bo, from sugar cane, on the complement system have been investigated. Bo, a glucan of about 10,000 mol wt, was found to activate complement in whole human and guinea pig serum in vitro by the classical pathway. Complement consumption was also demonstrated in guinea pigs upon intravenous injection. Specifically, C1 is activated, and C4 and C2, as well as C3, are consumed. The activation is prevented when Ca++ ions are chelated by ethyleneglycoltetraacetic acid, and when C1q is lacking. Hence, it does not rest on direct activation of C1s. Supplementation of C1q-deficient human serum with purified C1q restores the ability to be activated by Bo. The alternative pathway of complement is little if at all affected by the polysaccharide. The activation of C1 seems to be mediated by immune complex formation between Bo and naturally occurring immunoglobulins. Complement in sera from two severely hypogammaglobulinemic patients was not activated by Bo, but was made reactive by addition of purified human immunoglobulin G.

Adjuvants, Immunologic↗
PubMed1982

Chain structure of cobra venom factor from Naja naja and Naja haje venom.

The chain structure of cobra venom factor, whether isolated from Naja naja venom (CVFn) or from Naja Haje (CVFh) is similar. Both homologous proteins are composed of three disulphide-linked chains (A, B, and C) with apparent molecular weights of 72,000, 54,000, and 27,000-35,000 for CVFn and 68,000, 51,000 and 30,000-32,000 CVFh. That all three polypeptides are integral parts of CVF was demonstrated by investigation of the chain pattern after partial reduction. Reduction with 1-2 mM dithiothreitol under non-denaturing conditions yielded free B-chain, together with an intermediate product composed of disulphide-linked A- and C-chains. The C-chain was heterogenous when investigated by electrophoresis in polyacrylamide slab gels in the presence of SDS. Similarly, isoelectric focusing of CVFn and CVFh showed a multiplicity of bands in the pH range 5.2-6.4. Limited tryptic digestion resulted primarily in the fragmentation of the B-chain. CVFh is much more sensitive to tryptic attack than CVFn. In all our preparations of CVFh a partial, trypsin-like fragmentation of the B-chain was detectable to various extents.

Animals↗
PubMed1981

Analysis of free stool porphyrins by high-performance liquid chromatography.

The determination of stool porphyrins is necessary for the diagnosis of some porphyrias in clinical laboratories. Quantitative methods for the analysis of faeces for porphyrins are unpleasant and difficult to perform. An extraction and ion-pair reversed-phase high-performance liquid chromatographic procedure is described for the separation and determination of individual free stool porphyrins. The within-assay coefficients of variation range from 2 to 6%. A linear response curve is observed between 38 and 380 nmol/g for coproporphyrin I in dry stool The method can be applied to the routine analysis of free stool porphyrins in the clinical laboratory.

Chromatography, High Pressure Liquid↗
PubMed1981

Cluster-oriented discriminant analysis; taxonomic classification of the thyroid function.

A computer assisted procedure for the diagnosis of thyroid diseases, based on seven clinical chemical parameters, is proposed. The population studied consisted of 592 consecutive outpatients with a tentative diagnosis of thyroid disease. Thyroxine, triiodothyronine, T3 uptake test, TSH before and after TRH application, its difference and thyroxine binding globulin have been determined. The patients were clinically examined and in each case a Tc-scintigram was obtained. As a first step, 20 biochemical patterns were defined by cluster analysis (pattern cognition). T check how good in grouping process was, linear discriminant analysis was applied after which the reclassification rates were very satisfactory. The clusters found corresponded well to the pathophysiological situations with some exceptions. As a second step, patients were assigned to these patterns by use of the derived discriminant functions (pattern recognition). The proposed method seems to have some advantages over other diagnostic models published hitherto.

Alpha-Globulins↗
PubMed1981

Treatment of human complement components C4 and C3 with amines or chaotropic ions. Evidence of a functional and structural change that provides uncleaved C4 and C3 with properties of their soluble activated froms, C4b and C3b.

Treatment of human components C4 and C3 with amines like hydrazine, ammonium hydroxide, and neutral ammonium salts or with chaotropic salts like KSCN and NaBr leads to complete loss of haemolytic activity. The pretreated components are, however, still active in formation of soluble C3 convertases. This activity pattern is reminiscent of the activities of C4 and C3 that have been activated by cleavage in the fluid phase. Indeed, the antigenic properties of pretreated C4 and C3 are similar to soluble C4b and C3b. The polypeptide chain structure of pretreated C4 and C3, is, however, identical to that of the untreated components when investigated by SDS gel electrophoresis. Pretreatment even reduces greatly the susceptibility of C4 to cleavage by C1s and of C3 to cleavage by classical and alternative pathway C3 convertases. Pretreated components have lost the ability to combine with EAC1 and EAC142, respectively; this fact explains their failure to exhibit haemolytic activity. In serum, pretreated C4 and C3 are cleaved in a manner similar to C4b and C3b. Amines and chaotropic ions cause the same functional and structural alterations, which are best explained by assumption of a conformational change. A similar transformation can also occur in C4 and C3 during preparation or storage.

Amines↗
PubMed1981

Evaluation of a new valproic acid enzyme immunoassay and comparison with a capillary gas-chromatographic method.

A new homogeneous immunoassay (EMIT) for valproic acid was evaluated. Besides testing the manual version of this enzyme immunoassay, we also developed two mechanized procedures for centrifugal analyzers (the CentrifiChem and the COBAS system), which take less time and are more precise than the manual method. Within-assay precision (CV) was 4.5% with the manual technique and 2% with the analyzers. Between-assay precision (CV) ranged from 4 to 13% for all three techniques. Accuracy of th manual method was checked by dilution and analytical recovery experiments. Our comparison of the EMIT results with those obtained by a comparison method (capillary gas chromatography) showed no significant difference. No interference from hemolysis, hyperbilirubinemia, or aliphatic amino acids was observed. At high concentrations of bile acids and with lipemic sera the analytical recovery rates decreased slightly, to 87% and 92%, respectively.

Amino Acids↗
PubMed1981

[Determination of triiodothyronine in serum with a heterologous enzyme immunoassay: results of a group survey].

This paper summarises the results of the evaluation of a heterologous enzyme immunoassay in antibody coated tubes for the determination of triiodothyronine (T3) by a group of 11 laboratories. The assay procedure is analogous to an established heterologous thyroxine enzyme immunoassay. The evaluation demonstrated that 1. the specificity of the assay and its analytical range between 0.46 and 9.2 nmol/l meet diagnostic requirements, 2. the intra- and interassay precision was in accordance with that commonly found in radio immunoassays, 3. the recovery of added T3 was between 90 and 103%, 4. the results agreed well with those of self-established radio immunoassays and were comparable with commercial RIA kits, 5. there was no interference by hyperbilirubinaemia or by high concentrations of bile acids, but interference can occur in very haemolytic and lipaemic samples. The great advantage of T3 enzyme immunoassays lies in the absence of restrictions and any authorization needed for working with radioactive substances.

Evaluation Studies as Topic↗
PubMed1980

Highly sensitive method for the quantitation of homovanillic acid in cerebrospinal fluid.

Homovanillic acid in minute samples (50-100 microliters) of cerebrospinal fluid can be quantitated as its O-dimethylthiophosphinate methyl ester. The derivative is determined after glass capillary gas chromatography (GC) with high sensitivity by using a phosphorus-specific thermionic detector or by mass fragmentography, combined with a large sample volume split-splitless injector. The dimethylthiophosphinic esters show excellent stability against moisture and air. The precision of the overall procedure is 5.4% (GC) and 3.8% (GC-mass spectrometry). The method shows good linearity (r = 0.9999) over three orders of magnitude, from 500 pg to 500 ng. The lowest detectable concentration of homovanillic acid is 2-5 ng/ml. Concentrations of homovanillic acid determined in cerebrospinal fluid were 9.9-63.1 ng/ml (n = 10, mean = 30.9 ng/ml).

Dopamine↗
PubMed1980

Diagnosis of porphyrias by ion-pair high-performance liquid chromatography.

Ion-pair reversed-phase high-performance liquid chromatography together with fluorescence detection is useful in the analysis of urinary porphyrin carboxylic acids. The sensitive and quantitative detection facilitates the clinical diagnosis of porphyrias. The method described permits the detection of porphyrins down to 0.1 ng directly from urine without laborious sample pre-treatment. A linear response curve was obtained from 0.2 up to 200 ng for coproporphyrin I. The within-assay correlation coefficients ranged from 2.5 to 10.1%. Recovery experiments gave an accuracy of 89-109%. The rapidity and simplicity of the method allows its application to the routine analysis of urinary porphyrins in the clinical laboratory.

Chromatography, High Pressure Liquid↗
PubMed1980

Comparison of Naja n. naja and Naja h. haje cobra-venom factors: correlation between binding affinity for the fifth component of complement and mediation of its cleavage.

Two cobra-venom factors, one from Naja n. naja (CVFn), the other from Naja h. haje venom (CVFh), have been purified and compared, functionally and structurally. Both factors interacted with human factors B and DS to form a potent C3 convertase, CVFBb. However, while the convertase formed with CVFn did also efficiently cleave C5, CVFhBb had very little C5-cleaving potency only, in particular when human C5 was used as substrate. Studies with agarose-linked CVF preparations indicated that CVFh has only low binding affinity for C5gp and C5hu whereas CVFn binds to both C5 species with much higher affinity. Since C5-binding (to CVF or to C3b) is a prerequisite for its cleavage by C3/C5 convertases, the difference in binding potency explains the different C5-cleaving activity of the two CVF preparations. When a ligand for C5, surface-fixed C3b, is present, CVFhBb is also capable of cleaving C5. The difference in activities of CVFn and CVFh is reflected in their different potency to interfere with immune haemolysis and in causing indirect lysis by their complexes with activated factor B. By gel chromatography of the CVF preparations in C5-containing medium, a stoichiometric complex CVFn-C5 (1 + 1) could be demonstrated. An analogous complex of C5 was neither found with CVFh, nor with C3hu or soluble C3bhu. Structural differences between CVFn and CVFh were revealed by immunodiffusion analysis and by polyacrylamide-gel electrophoresis in presence of SDS. The data available so far provide, however, no clear information about the structure of the C5 binding site.

Animals↗
PubMed1980

Aggregation of leukocytes induced by the complement-derived peptides C3a and C5a and by three synthetic formyl-methionyl peptides.

The highly purified hog complement peptides C3a and C5a and three formylmethionyl peptides induced dose-dependent aggregation of human leukocytes. For the effect Ca2+ and Mg2+ ions were required; in their absence the peptides induced specific desensitization. Human serum albumin (1 and 2%) reduced aggregation, whereas equivalent or even higher concentrations of plasma or serum were not inhibitory. SH reagents, protease inhibitors (N-tosyl-L-lysyl-chloromethyl ketone, N-tosyl-L-phenylalanyl-chloromethyl ketone), and colchicine also inhibited aggregation, whereas cytochalasin B greatly enhanced it. Dose-response studies under comparable conditions showed that aggregation is induced in similar dose ranges as chemotaxis. This suggests that complement-derived peptides generated in vivo may contribute to leukocyte accumulation in two ways, first by causing adherence of leukocytes to endothelium (equivalent to aggregation) and then by promoting migration to the inflammatory site.

Calcium↗
PubMed1980

Biological activities of C5a and C5adesArg from hog serum.

The complement-derived peptides C5a and C5adesArg (highly purified from yeast-activated hog serum) were both active in the following biological assays: in aggregation of human leukocytes (potency ratio for C5a:C5adesArg 3:1), in aggregation of guinea pig platelets (10:1), in chemotaxis of peritoneal rabbit leukocytes (10:1), and in contraction of isolated guinea pig ileum (1.4:1). The fact that C5adesArg preparations have 30 and 40% of the activity of C5a in leukocyte aggregation and smooth muscle contraction but only 10% of C5a chemotactic activity, clearly indicates that aggregation and spasmogenic activity are inherent properties of C5adesArg. Evidence that C5adesArg owns all activities studied is further given by the following findings: chromatographic separation of mixtures of C5a and C5adesArg results in the appearance of two peaks of spasmogenic activity; treatment of C5adesArg with carbopeptidase B does neither lead to release of detectable arginine nor abrogate any of the biological effects; treatment of C5a with carboxypeptidase B reduces the activities quantitatively to those of C5adesArg, and liberates the theoretically expected amount of arginine.

Amino Acids↗
PubMed1980

Purification and partial amino acid sequence of classical anaphylatoxin from pig serum: identification with Des-Arg-C5a.

Complement was activated in hog serum and the biologically active peptide(s) derived from the fifth component of complement were purified. Treatment of the serum with yeast, without any precautions to inhibit serum arginine carboxypeptidase, allowed the recovery of only one active fraction, the classical anaphylatoxin; it was identified as des-Arg-C5a. When hog serum was activated with yeast in the presence of 1M epsilon-aminohexanoic acid (inhibitor of arginine carboxypeptidase), two active C5-derived fractions were obtained, C5a and des-Arg-C5a. A partial amino acid sequence of the classical anaphylatoxin (19 N-terminal and 12 C-terminal amino acids) has been elaborated. With one exception it is identical with hog C5a as far as that structure is known (12 N-, 3 C-terminal amino acids). The only difference is the C-terminal region: arginine, present in C5a, is absent from des-Arg-C5a which ends with ... Asn-Ile-Gln-Leu-Gly-OH. The finding that des-Arg-C5a, virtually free of any significant contamination with C5a, has considerable spasmogenic activity demonstrates that it is the classical anaphylatoxin, and that for spasmogenic activity arginine as the C-terminal amino acid is not absolutely essential.

Amino Acid Sequence↗