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Biomedical subjects

U Hadding

Publications and source records attributed to U Hadding.

At least 73 records · Page 4Linked to original sources
PubMed1981

Linkage of total deficiency of the second component (C2) of the complement system and of genetic C2-polymorphism to the major histocompatibility complex of the guinea pig.

In the guinea pig six common phenotypes for hemolytically active C2 were detected. They resulted from three allotypic variants: a basic C2B and two more acidic variants C2A and C2A1. (The gene frequency for C2B in the outbred population was 0.36, 0.33 for C2A, and 0.31 for C2A1.) These variants were inherited as autosomal codominant traits. A strong linkage-disequilibrium between C2 and C4 allotypes was observed consisting of the pairs C2A1-C4F. C2A-C4S, whereas C2B was associated with either C4S or C4S1. To investigate the linkage of C2 to the MHC a family of strain 2 X strain OM3 was studied: the C2B allotype segregated with the strain haplotype of OM3 whereas C2A1 does the same with the strain 2 haplotype. During the C2-typing, an animal totally deficient in hemolytic C2 activity was discovered. Its C1, C4, C3, C5, factors B, D, and H were normal. Breeding yielded finally homozygous and heterozygous-deficient individuals. The latter ones exhibited 50 to 60% of the hemolytic activity of normal guinea pigs. Combined typing data of C4, C2 and GPLA showed that the deficient gene behaved like a rare, silent allele of C2, which is GPLA-linked and inherited like the normal C2-variants. An antiserum against C2 was raised in C2-deficient animals, which reacted with normal guinea pig serum but not with serum from C2-deficient animals. No cross-reactivity with human or mouse serum could be detected.

Alleles↗
PubMed1979

Killing of tumor cells in vitro by macrophages from mice treated with synthetic dehydrodipeptides.

Treatment of NMRI mice i.p. with dehydrodipeptides [acetyldehydro-3-(2-thienyl)alanyltyrosine (SI); acetyldehydro-3-(2-furyl)alanyltyrosine (SII)] rendered macrophages cytolytic for several tumor cells in vitro. Normal peritoneal mouse macrophages from untreated mice not given injections of the peptides or from control mice given injections of phosphate-buffered saline were not cytotoxic. Moreover, supernatants from these in vivo-activated mouse peritoneal macrophages significantly increased the release of the cytoplasmic enzyme lactate dehydrogenase from freshly added target cells, showing that these cells had been killed. The macrophage activation to lyse tumor cells was sharply dose dependent and appeared about 48 hr after injection of the peptides. Although dehydrodipeptide SI was active in vivo at concentrations as low as 500 microgram/mouse, the same substance lacked activity in vitro at all concentrations tested up to 800 microgram/ml. Dehydrodipeptides activate macrophages through a T-cell-independent process to lyse tumor target cells. Macrophages from athymic nude (nu/nu) mice were less cytotoxic, but they still were stimulated; and the culture supernatants could kill about 50% of the tumor cells used. There are indications for a relative specific structure-activity relationship of dehydrodipeptides for inducing cytotoxic macrophages.

Animals↗
PubMed1978

Platelet activation: a new biological activity of guinea-pig C3a anaphylatoxin.

3H-serotonin-release from labelled gp-platelets is established as a sensitive method for testing a new biological activity of gp-C3a anaphylatoxin in an autologous situation. Time-, dose- and temperature-dependent release reactions as well as specific inhibition by carboxypeptidase B and anti-C3a antibodies show that C3a is a potent and specific inducer of platelet activation. Inactive C3a does not induce 3H-serotonin-release but specifically inhibits the action of C3a on platelets.

Anaphylatoxins↗
PubMed1978

Demonstration of high-affinity binding sites for C3a anaphylatoxin on guinea-pig platelets.

3H-serotonin release from guinea-pig platelets was demonstrated to be the consequence of C3a binding to these cells. A Scatchard analysis of dose-response data of the 125I-C3a binding pattern to guinea-pig platelets pointed to the existence of binding sites with high and low affinity for the C3a molecule (HA and LA receptors). HA receptors are specific for C3a with intact C-terminal arginine. whereas C3adesarg only interacts with LA receptors. The release of serotonin may be induced by a combined reaction of C3a with HA receptors and LA receptors on the platelet membrane.

Anaphylatoxins↗
PubMed1978

Solid phase activation of alternative pathway of complement by beta-1,3-glucans and its possible role for tumour regressing activity.

The efficiency of some anti-tumour polysaccharides, such as lentinan, pachyman, pachymaran, carboxymethylpachymaran and hydroxyethylpachyman to trigger the alternative pathway of complement activation (APC) was investigated in detail, in order to clarify whether solid phase activation of APC by these polysaccharides will occur or not. From the eight polysaccharides tested, all were found to be potent activators of the alternative pathway except for carboxymethylpachymaran, regardless of their potency of inhibition of sarcoma 180 (S 180) transplanted in mice. This activation was observed both for the insoluble as well as the soluble part of the same polysaccharide. The turnover of C3, C5 and factor B showed no difference among these seven active polysaccharides. The polysaccharide particles (PX), isolated after treatment with C4d GPS showed prominent C3 consuming activity, which disappeared during prolonged incubation at 37 degrees. The activity of the decayed enzyme could be regenerated by treatment with the purified factor B. The stability of the particulate enzyme PX was comparable to the zymosan-complex (ZX) previously described.

Animals↗
PubMed1978

Fragments Ba and Bb derived from guinea pig factor B of the properdin system: purification, characterization, and biologic activities.

Functionally active guinea pig factor B was purified by a combination of chromatographic steps including Sephadex G-25, QAE A25, QAE A50, CM C50, and Sepharose 4B coupled with purified cobra venom factor. Purified factor B had a m.w. of 106,000 daltons and a single subunit structure. It was heat labile. After cleavage of native B with cobra venom factor coupled to Sepharose 4B in the presence of D, the resulting two fragments, the larger one (Bb) and the smaller one (Ba), were further purified. The m.w. of Bb and Ba was determined as 64,000 and 53,000 daltons, respectively, by SDS-PAGE. Neither of the fragments evoked a contraction of guinea pig ileum or histamine release from rat mast cells. Only the smaller fragment Ba (at a concentration of 120 nM) stimulated guinea pig peritoneal polymorphonuclear leukocytes to respond with increased movement. This activity as well as the antigenicity of Ba were heat stable, but were sensitive to trypsin digestion, whereas the antigenicity of Bb was heat labile.

Anaphylatoxins↗
PubMed1978

The anaphylatoxic peptide C3a of guinea pig complement. I. Purification, physicochemical and antigenetic properties.

Highly purified guinea pig C3a was obtained after specific cleavage of isolated C3 by the alternative pathway enzyme VF-B in a one step procedure. It turned out to be a low molecular weight peptide with basic character (M.W. 9500; isoelectric point above 9.4). C3a represents an antigenetic determinant of its own in the native C3 molecule, different from the B determinant. Guinea pig C3a resistant to 100 degrees C for 10 minutes. Its smooth muscle contracting activity can be destroyed by trypsin and carboxypeptidase B. These findings indicate that guinea pig C3a is quite similar to human C3a.

Anaphylatoxins↗
PubMed1977

Studies on C3 convertases. Inhibition of C5 convertase formation by peptides containing aromatic amino acids.

The influence of various peptides containing the aromatic amino acids phenylalanine and tyrosine on the formation of the enzyme EAC1423 of the complement system from component C3 and enzyme EAC142 was investigated. Kinetic analysis of enzyme EAC1423 formation and studies on the binding of the C3b fragment of 125I-labelled component C3 to enzyme EAC142 both showed that binding of the C3b fragment of component C3 was decreased by the peptides. Kinetic studies on component-C3 turnover in the fluid phase of enzyme EAC142 failed to reveal effects of the peptides. However, an initial lag in component-C3 turnover occurred that at constant component-C3 concentration was inversely proportional to enzyme EAC142 concentration. This lag in enzyme EAC142 activity is considered as an indication that the interaction of enzyme EAC142 with component C3 possibly does not follow simple Michaelis-Menten kinetics, as was previously assumed. It is shown that the stages after enzyme EAC1423 formation are not influenced by the peptides, suggesting a high degree of specificity of the peptides for the inhibition of enzyme EAC1423 formation.

Complement Activating Enzymes↗
PubMed1977

Effect of in vivo stimulation of mice on the secretion of factor B of the alternate complement pathway by peritoneal macrophages.

After in vivo treatment of mice with thioglycollate medium, the amount of native factor B which could be detected in vitro in culture supernatants of peritoneal macrophages was much lower than that found in supernatants of macrophages taken from untreated mice. However, when the macrophages from thioglycollate medium-treated mice were cultured on a plastic surface covered with glutardialdehyde-linked bovine serum albumin, the culture supernatants contained larger quantities of native factor B than culture supernatants of macrophages from untreated mice under the same conditions. Thus, the effect of in vivo thioglycollate medium treatment on the in vitro secretion of factor B by peritoneal macrophages could be modulated by the culture conditions. Factor B in culture supernatants of macrophages obtained from both untreated and thioglycollate medium-treated mice was stable. It remained functionally active, and therfore uncleaved over a long incubation period at 37 degrees C. In addition, factor D activity was never detected in any culture supernatant.

Animals↗
PubMed1977

Interaction of zymosan and of activated properdin with factor D-depleted guinea pig serum: implications for the mechanism of initial C3 cleavage via the alternative complement pathway.

Factor D of the alternative C pathway was specifically removed from guinea pig serum. The resulting serum reagent (RD) supported neither the formation of a C3-cleaving enzyme on zymosan (Z) nor the inactivation of C3 or of factor B in the presence of Z or activated properdin (P). Addition of purified D to RD restored these properties. Studies were limited amounts of purified D were added to RD with Z or P as activating substances, gave the following results: (1) Inactivation of B and of C3 occurs in the presence of minute amounts of D. (2) C3 inactivation is more efficient than B inactivation and proceeds even in the absence of detectable enzymatic B activation. (3) C3 cleavage at any D concentration tested is always accompanied by uptake of C3 fragments onto Z. With respect to initial C3 cleavage via the alternative C pathway these data suggest that the initiating reaction is D-dependent, very efficient in depositing C3 fragments on particulate activating substances such as Z and able to utilize factor B in an apparently uncleaved form.

Animals↗
PubMed1977

Inherited polymorphism of guinea pig factor B and C4: evidence for genetic linkage between the C4 and Bf loci.

An inherited structural polymorphism of the guinea pig complement protein C4 and of factor B of the alternative pathway was demonstrated by use of high voltage agarose electrophoresis combined with a subsequent immunofixation technique. No polymorphism of guinea pig C3 could be shown. Three common allelic genes were proven to code for C4-S, C4-S1, and C4-F, respectively. Two common allelic genes are responsible for the Bf-F and Bf-S phenotype expression. A strong linkage disequilibrium between both C4 and Bf was demonstrated.

Animals↗
PubMed1977

Linkage of guinea pig Bf and C4 TO THE GPLA.

Inbred and partially inbred strains of guinea pigs were typed for their polymorphic Bf and C4 patterns. In crosses and backcrosses of inbred strains of guinea pigs the inheritance of Bf, C4, and GPLA phenotypes was studied. The presented data indicate linkage of the structural Bf and C4 loci to the major histocompatibility complex (MHC) of the guinea pig, the GPLA system. Evidence for a GPLA-B-Ia crossover was obtained. Bf and C4 typing contributes to the characterization of the GPLA region in some inbred strains thus providing a simple method for determining the state of inbreeding on the one hand and providing the necessary third or fourth region within the GPLA for the detection of informative meiosis, on the other.

Animals↗