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Biomedical subjects

H Huser

Publications and source records attributed to H Huser.

At least 19 recordsLinked to original sources
PubMed1997

Intracellular metabolism of 4-hydroxynonenal in primary cultures of rabbit synovial fibroblasts.

The intracellular metabolism of 4-hydroxynonenal (HNE), a secondary product of lipid peroxidation and mediator of inflammation, which was found in the joints of patients with rheumatoid arthritis, was investigated in primary cultures of rabbit synovial fibroblasts. A consumption rate of 27.3 nmol/min x 10(6) cells was measured for the cultivated fibroblasts. It could be shown, that 4-hydroxynonenal enters the synovial fibroblasts and is metabolized mainly oxidatively to 4-hydroxynonenoic acid, intermediates of the tricarboxylic acid cycle and water and by formation of the glutathione-HNE adduct. The share of protein-bound HNE was about up to 8% of the total added HNE after 10 min of incubation. All metabolites accumulates intracellularly within the incubation time except of 4-hydroxynonenal itself. An increase of 4-hydroxynonenoic acid could be detected also extracellularly during the intracellular metabolism of 4-hydroxynonenal. Therefore, an involvement of synovial fibroblasts in the secondary antioxidant defense system of the joints during conditions of higher HNE concentrations like rheumatoid arthritis is suggested.

Aldehydes↗
PubMed1996

Inhibition of poly(ADP-ribose) formation by 4-hydroxynonenal in primary cultures of rabbit synovial fibroblasts.

The formation of poly(ADP-ribose) in primary cultures of rabbit synovial fibroblasts after treatment with active oxygen released by xanthine/xanthine oxidase is inhibited by addition of 1 and 10 microM 4-hydroxy-2,3-trans-nonenal (HNE). The endogenous formation of HNE by the xanthine/xanthine oxidase system is not responsible for the inhibitory effect of the aldehyde, owing to the low accumulation rate of the lipid peroxidation product in the system used. HNE is able to inhibit the isolated nuclear enzyme ADP-ribosyltransferase, as shown by an in vitro assay with an Ki of 4 mumol/litre. Therefore the molecular basis of HNE-mediated effects on cell proliferation, differentiation and transformation might be due to the inhibitory effect of poly(ADP-ribos)ylation.

Aldehydes↗
PubMed1995

Induction and activation of procollagenase in rabbit synovial fibroblasts after treatment with active oxygen released by xanthine/xanthine oxidase.

Treatment of rabbit synovial fibroblasts with active oxygen (AO) released by xanthine/xanthine oxidase resulted in an induction of procollagenase in these cells in concentrations ranging from 12.5 micrograms/ml xanthine plus 0.0025 U/ml xanthine oxidase to 50 micrograms/ml xanthine plus 0.01 U/ml xanthine oxidase. Preceding this there was an accumulation of poly(ADP-ribose) for the same concentration range of xanthine/xanthine oxidase. Furthermore, it was found that AO caused activation of the latent procollagenase to the active enzyme in concentrations ranging from 0.1 micrograms/ml xanthine plus 0.00002 U/ml xanthine oxidase to 1 microgram/ml xanthine plus 0.0002 U/ml xanthine oxidase. It is suggested that poly(ADP-ribosyl)ation participates in the induction of procollagenase by relaxing chromatin. Furthermore, it is proposed that AO activates latent procollagenase under physiological conditions.

Animals↗
PubMed1995

Inhibition of the induction of collagenase by interleukin-1 beta in cultured rabbit synovial fibroblasts after treatment with the poly(ADP-ribose)-polymerase inhibitor 3-aminobenzamide.

3-Aminobenzamide is an inhibitor of poly-(ADP-ribosyl)ation. In concentrations from 3 to 10 mM it reduced the collagenase activity in culture supernatants of interleukin-1 beta-stimulated rabbit synovial fibroblasts. 3-Aminobenzoate, not an inhibiter of poly(ADP-ribosyl)ation, had no effect on collagenase activity at a concentration of 10 mM. We concluded that poly(ADP-ribosyl)ation plays a role in the induction of the expression of collagenase and that 3-aminobenzamide can inhibit this process.

Animals↗
PubMed1994

Isolation of latent 31-kDa C-truncated stromelysin and 21-kDa stromelysin from rabbit synovial fibroblasts: an alternative activation pathway for stromelysin.

The processing of culture medium of rabbit synovial fibroblasts led to the isolation of three stromelysin-1 (MMP-3) cleavage products: A 31-kDa protein, which represents a C-truncated latent stromelysin-1, an active stromelysin-1 of 21 kDa, that originates from the 31-kDa proform by activation. A third protein had a molecular mass of 25 kDa representing the C-terminal part of prostromelysin-1 and is missing in the C-truncated latent stromelysin-1. The activation process of human prostromelysin-1 in vitro is known to lead to an active stromelysin-1 with a relative molecular mass of 45 kDa by removing the N-terminal prodomain. This active stromelysin-1 is further processed to a lower molecular mass active form of 28 kDa. Our results obtained for the highly homologous rabbit stromelysin-1 indicate that another activation pathway is possible. In a first step prostromelysin-1 is hydrolysed between Met261-Glu generating a C-truncated latent stromelysin-1, which is activated by cleavage of the Thr83-Phe bond to the 21-kDa stromelysin-1. The latent C-truncated stromelysin-1 is slowly converted even at 4 degrees C into the active form. In the presence of 50 microM ZnCl2 this activation was prevented for at least three weeks. The activation rate is largely enhanced by aminophenylmercury acetate and especially by trypsin. The differences of the 21-kDa stromelysin-1 to a 28-kDa stromelysin-1 isolated from human rheumatoid synovial fluids described earlier are discussed.

Amino Acid Sequence↗
PubMed1991

Proto-oncogene expression in cultured synovial fibroblasts of patients with rheumatoid arthritis.

Total RNA was isolated from cultured synovial fibroblasts of nine patients with rheumatoid arthritis and two controls (cruciate ligament ruptures). RNA was dot-blotted and hybridized with nine different, cloned cellular or viral oncogene probes. None of the proto-oncogenes showed a significant difference of expression in cultured fibroblasts from patients with rheumatoid arthritis when compared to the expression of control fibroblasts.

Arthritis, Rheumatoid↗
PubMed1988

Short-lasting accumulation in osteoid bone seams of radioactive iron injected as citrate into mice.

The possible role in vivo of osseous structures in binding radioactive iron injected as a low-molecular-weight complex was studied in mice, using combined autoradiography and histomorphometry on sections of undecalcified, plastic-embedded femur epiphyses/metaphyses. A single intraperitoneal injection of 10 microCi 59Fe (1.2 micrograms Fe) per animal as citrate within 3 hours led to a preferential accumulation of this metal in the osteoid mineralized tissue interphase (osteoid seams) of bone. Within the next 2 days the labeling intensity in this localization diminished markedly to approximate levels of the bone marrow and calcified bone. The bulk of the injected radioiron was utilized according to known erythrokinetics. Findings suggest a direct entry of "free," ie, not transferrin-bound, iron into osteoid seams and its consecutive rapid removal from this site.

Animals↗
PubMed1983

Separation and characterization of two isolated lipases from Staphylococcus aureus (TEN5).

The purified lipases from Staphylococcus aureus (TEN5) showing two enzymatically active protein bands on SDS-polyacrylamide gel electrophoresis have been separated by ion-exchange chromatography. The separated proteins show some properties which are different (e.g., apparent molecular weight, charge, binding of detergent, enzymatic activity towards triolein) and some which are almost identical (spur in immunodiffusion).

Chemical Phenomena↗
PubMed1983

Fermenter growth of Streptococcus agalactiae and large-scale production of CAMP factor.

Streptococcus agalactiae (group B) was grown in Todd-Hewitt broth (36.4 g l-1, pH 7.8) in a Braun Fermenter (type B20) to investigate the conditions of optimal bacterial growth and maximal production of CAMP factor. The influence of different gas atmospheres (air, N2, CO2, and gas mixtures) on growth, CAMP production and chain length of S. agalactiae was studied. The organisms grew best in the presence of 2% (w/v) glucose, at pH 6.2, with a constant flow of CO2. The number of diplococci and monococci under these conditions reached almost 80% of the total population.

Bacterial Proteins↗
PubMed1982

Early and late events in streptolysin-O induced hemolysis.

Treatment of erythrocytes with activated Streptolysin (SLO) resulted in a "swelling" of the target cells. The mean cell volume (MCV) of toxin treated human - sheep - and rabbit red blood cells increased by about 15% of the original value as measured in the Coulter Counter apparatus. Release of hemoglobin was influenced by the addition of high molecular weight colloids. In contrast ATP release was independent of the osmolarity and started before an increase in MCV was observed. The experiments indicated that "colloid osmotic lysis" is involved in SLO induced hemolysis.

Adenosine Triphosphate↗
PubMed1979

The VkVI subgroup of rabbit light chains: complete amino acid sequence of a third variable region (K29-213).

The amino acid sequence of the variable region of a rabbit anti-streptococcal A-variant antibody light chain was determined. By using a combination of different cleavage methods, the sequence was established. Large peptides were sequenced in an extensively modified Beckman sequentor. Light chain K29-213 belongs to a rare subgroup (kVI). Several of these light chains of antibodies with different specificities have been totally or partially sequenced. Comparison of these light chains reveals at least four germ-line-encoded variants within this subgroup.

Amino Acid Sequence↗
PubMed1979

Amino acid sequences of antibody light chain variable regions of pedigreed rabbits: kappa light chain K49-501 (allotype b4 anti-streptococcal group A-variant polysaccharide antibody).

The amino acid sequence of positions 1--150 of a light chain, isolated from another monoclonal rabbit anti-streptococcal group A-variant polysaccharide antibody, was determined. The analysis was performed with 2 mumol of polypeptide chain, using a grossly modified Beckman 890B sequenator. This sequence stretch accounts for the whole variable region and a considerable part of the constant region at a total length of 218 amino acids. This allotype b4 light chain was isolated from a non-precipitating, end-group-specific antibody with a KD = 1.3 X 10(-5)M. This brings the present number of totally known rabbit VL sequences of antigen elicited antibodies to 21. A comparison of these 21 sequences reveals a building plan of ribbit VL homologous to that of human and murine VL regions. The observed variability does follow a pattern of linked amino acid substitutions, indicating that this information must be contained in the germ-line of the rabbit in the form of multiple VL region genes. This conclusion, however, does not rule out the occasional variant being due to somatic rearrangement. Finally, this comparison reveals that the joining peptide between positions 96--110 is also a separate entity in rabbit VL region sequences.

Amino Acid Sequence↗
PubMed1978

Variable-region subgroup and specificity of cold agglutinins.

The variable-region subgroup determined by amino acid sequence analysis of heavy and light chains of two monoclonal cold agglutinins with the new anti-Gd specificity is reported. Both proteins belong to the VHIII subgroup of heavy chains; one light chain falls into the V kappaI subgroup, the other has a blocked N-terminus which so far has not been observed in human kappa chains. The comparison of anti-Gd with anti-I/-i or anti-Pr cold agglutinins indicates that anti-Gd differs from other cold agglutinins with respect to variable-region subgroup. The data extend previous findings on the restriction of certain antibodies to distinct variable-region subgroups.

Agglutinins↗
PubMed1978

Rabbit variable kappa light chain regions: subgroups contain polypeptides encoded by multiple genes.

Two identical light chain variable regions were identified in anti-streptococcal Group A-variant antibodies elicited in litter-mate rabbits by hyperimmunization with vaccine. In addition, one rabbit produced two additional clonally restricted antibodies to this polysaccharide antigen. The partial amino acid sequence of the light chain of one of these antibodies was identical with the dominant antibody light chain sequence, while the light chain of the other antibody, also partially established, showed significant variations in the framework-associated regions with identical CDRI and II. Since all of these light chains were from a small subset of rabbit kappa light chain pools (b4 allotype) the data suggest, together with other light chains reported in the literature, that more than one copy of variable region genes are present in the germ-line per subgroup. Furthermore, framework associated amino acid substitutions are not random; this suggests the existence of some "ordered" mechanism for linked amino acid substitutions (presumably recombination). Furthermore one light chain can pair with more than one heavy chain to yield functional antibodies.

Amino Acid Sequence↗
PubMed1976

Rabbit antibody light chains: selective breeding narrows variability in framework and complementarity-determining residues.

The amino acid sequence of 5 light (L) chain (b4) variable (Vl) regions and the partial sequence of VL (kappa) regions from 12 anti-streptococcal group A-varant polysaccharide (Av-CHO) and 2 anti-streptococcal group C polysaccharide (C-CHO) antibodies was determined. These sequences contain 70 invariant positions as opposed to 50 invariant positions in other rabbit VL regions. Variability within the framework residues lacks randomness, and parent offspring relationship or otherwise close familial relationship is apparent in several instances. Variability in the complementarity-determining regions is reduced by 2.3-5.5-fold in comparison with other rabbit L-chains with several identical first and third hypervariable regions. Residue positions 50-56, known to mark the second hypervariable region in human kappa-chains, are not hypervariable in L-chains from Av-CHO rabbit antibodies. Considering the 67 rabbit L-chain sequences, completely or partially known today, for counting the number of V region germ line genes, it is concluded that the species rabbit has at least 27 VL germ line genes available.

Amino Acid Sequence↗
PubMed1976

Active heterologous chain recombinants of monoclonal antibodies raised in related rabbits.

Heterologous chain recombinants of homogeneous anti-streptococcal group A-variant polysaccharide antibodies produced by pedigreed rabbits regain in certain pairs the same antigen-binding capacity as the homologous pairs. In contrast, chain recombinants with antibodies from nonrelated rabbits are much less active. This data suggests random pairing of immunoglobulin heavy and light chains coded for in the germ line and subsequent selection.

Animals↗
PubMed1976

The binding of complement by complexes formed between a rabbit antibody and oligosaccharides of increasing size.

Immune complexes formed between a homogeneous rabbit antibody to type III pneumococcal polysaccharide and a series of oligosaccharides of varying size derived from it were prepared and tested for their ability to fix guinea pig hemolytic complement. Antibody and either tetra-, hexa-, or octasaccharide formed only monomeric antibody-hapten complexes and did not show any complement binding. A dodecasaccharide and a 16-sugar residues oligomer formed dimer and trimer immune complexes. These complexes were also unable to fix complement. However, as the size of the sugar oligomers was increased to about 21 sugar residues per oligosaccharide molecule or more, the resulting complexes exhibited substantial complement binding, concomitant with the formation of antigen-antibody aggregates higher than trimers. On the other hand, an independent study carried out with the same material suggested changes in the conformation of the Fc moiety in the antibody molecule upon addition of oligosaccharide ligands as small as a 16-residue unit. Since the resulting complexes hardly ehibited any complement binding, ligand-induced conformational changes in the Fc part of the antibody molecule appears to be an insufficient condition per se for triggering complement fixation.

Animals↗