Biomedical subjects

E J Menzel

Publications and source records attributed to E J Menzel.

78 records · Page 5Linked to original sources

PubMedDate not supplied

Binding of long-term glycated low density lipoprotein and AGE-albumin by peripheral monocytes and endothelial cells.

Modification of low density lipoprotein (LDL) and plasma or tissue proteins by non-enzymatic glycation culminating in the formation of advanced glycation endproducts (AGEs) is one of the essential pathomechanisms leading to diabetes-associated long-term complications. We compared binding of glycated, glycoxidated and oxidated LDL by peripheral monocytes in activated and quiescent form. Interaction via specific receptors was different for glycated as compared to (glyc)oxidated LDL-modifications. In addition, binding of glycated LDL to quiescent and activated human umbilical vein endothelial cells was studied. In patients with insulin-dependent diabetes mellitus (IDDM), AGE-binding was significantly increased as compared to healthy individuals. Specific and non-specific monocyte binding mechanisms were detected, and both were significantly increased in IDDM patients. Specific and non-specific binding strategies possibly act in concert to eliminate circulating AGEs, which are instrumental in the development and progress of microangiopathic and macroangiopathic complications of diabetes mellitus.

Binding Sites↗

PubMedDate not supplied

Mechanical changes in rat tail tendons induced by dibasic amino acids as a function of age.

Rat tail tendons from 54-day-old and 900-day-old animals were incubated with different concentrations of the dibasic amino acids, lysine and arginine. We observed a significant incorporation of these amino acids into the tendons. Uniaxial tension tests and relaxation experiments were performed at strain levels within the linear portion of the stress-strain relationship. The incorporation of the amino acids resulted in a decrease of ultimate stress and maximum Young's modulus and, after separation of the elastic and viscous stress components, in a decrease of the elastic fraction. The incorporation of amino acids and the resulting mechanical alterations were more pronounced in the young animals. The reversibility of the effects induced by the amino acids was tested. After the glycosaminoglycan chains were digested with chondroitinase ABC, we showed that the dibasic amino acids bind predominantly to the proteoglycan matrix. A possible analogy to the effects of amino acid incorporation on biomechanics and swelling with a monovalent cation such as Na+ is discussed.

Aging↗

PubMedDate not supplied

Rheumatoid factor isotypes and circulating immune complexes in rheumatoid arthritis.

Solid phase enzyme immunoassays were here used to quantify rheumatoid factors (RF) of the IgM, IgG and IgA classes and the immune complexes (IK) by their ability to bind to C1q or conglutinin in both the serum and synovial fluid of patients with rheumatoid arthritis (RA). Elevated serum levels of any RF isotype could be found in all patients with seropositive RA (IgM: 63%, IgG: 87%, IgA: 90%). Seronegative patients with RA presented to a significantly lesser extent with elevated levels of all the RF isotypes tested (IgM: 0%, IgG: 40%, IgA: 32%). Synovial fluid RF levels were significantly higher in SPRA patients than in SNRA patients with the exception of IgG-RF. All of the RF classes in both RA groups, however, were elevated when compared to RF in the synovial fluid of patients with osteoarthrosis. Both C1q binding and conglutinin binding immune complexes were significantly higher in the synovial fluid than in the serum of RA patients. The erythrocyte sedimentation rate and plasma iron levels were correlated with the levels of C1q binding immune complexes (IC) in the synovial fluid; total iron binding capacity showed an inverse relationship to synovial fluid IgG-RF levels. A radiographic index was also correlated with IgG-RF levels in the synovial fluid. Extraarticular manifestations were significantly more frequent in patients with elevated serum levels of IgM-RF or conglutinin binding IC. These findings indicate that IgG-RF in the synovial fluid and the formation of IC determined by their ability to bind C1q seem to be closely related to clinical features of local disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

[Plasma fibronectin in the aged].

Biochemical and functional characteristics of the plasma fibronectin in very old human individuals (within the range 86a-95a) were investigated. While the molecular weight was unchanged as compared to control fibronectin, binding experiments showed a clear-cut reduction in the affinity to gelatin. The opsonizing activity for connective tissue fragments liberated by thermal injury or operation trauma is therefore reduced in old age and such particles are removed from the circulation at a slower pace. In contrast to the elevated plasma fibronectin concentration this group of very old people showed no general irregularities as far as acute phase proteins are concerned. In addition, the hemolytical activity of C1 and C3 complement components, which both form complexes with fibronectin, was unchanged.

Acute-Phase Proteins↗

PubMedDate not supplied

[Interactions between collagen and C1q: their significance for rheumatology].

Interactions between C1q and collagen are thought to be due to the similarity in the structure of collagen and part of C1q. In the present paper immunological and biochemical aspects of this similarity were explored. It was found that one of nine rabbit anticollagen sera studied showed a clearcut reactivity with C1q, while anticollagenantibody-positive sera and synovial fluids of patients with rheumatoid arthritis did not display any cross-reactivity with C1q. Eleven of twenty collagen-immunized guinea pigs, however, demonstrated cellular cross-reactivity with CLF, the collagen-like fragment of C1q. Gel filtration studies indicated the formation of complexes between CLF and collagen, simulating immunological inhibition of anti-C1q-antibody by collagen. Human RA synovial collagenase was found capable of splitting C1q at a position within its collagen-like fragment. The importance of the interactions between collagen and C1q for the pathological events characterizing RA is discussed.

Animals↗

PubMedDate not supplied

Effect of glycosaminoglycans on the detection of antibodies to collagen in synovial fluid.

Antibodies to collagen in the synovial fluid of RA patients were determined by radioimmuno assay using 14-C-labeled collagen and by passive hemagglutination with collagen coated erythrocytes. The effect of various glycosaminoglycans, possibly present in synovial fluid, on these two assays was investigated. None of the glycosaminoglycan preparations tested significantly changed either antibody titers or the amount of 14-C-radioactivity precipitated in radioimmunoassay. Digestion of the synovial fluid with chondroitinase ABC likewise had no effect on the results. It is therefore concluded that the glycosaminoglycans present in synovial fluid do not interact with native or denatured collagen under the experimental conditions existing in the determination of antibodies to collagen.

Antibodies↗