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Results for “Enzyme Reactivators”

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PubMedDate not supplied

[Expression of NADPH-diaphorase in the peripheral nerve and its changes at different stages of diphtheritic polyneuropathy].

Distribution and intensity of NADPH-d reactivity, a marker for enzyme of the nitric oxide synthesis, in nervus suralis biopsies in severe DP were studied at light and electron microscopic levels. The study of control specimens has shown that NADPH-d reactivity was permanently present in Schwann cells (SC) and was distributed in all parts of their cytoplasm. Axon and myelin were devoid of NADPH-d reactivity. A decrease of enzyme reactivity in SC cytoplasm of the damaged nerve fibers and rising enzyme reactivity in the cytoplasm of activated SC were observed in DP. High reactivity in SC of small fibers was found at earlier stages and that of thick fibers at later stages. This distinction reflected, apparently, sequence of entering at first thin, then thick fibres in the reparative process. Under the electron microscope, the reaction product was deposited on membranes of endoplasmic reticulum, nuclear membrane and Golgi complex. The enzyme was also located in nucleus of activated SC. Ultrastructural location and the fact that the highest intensity of reaction is present in SC of nervous fibres with morphological signs of remyelination suggest link of this enzyme with the reparative process. This study provides the first evidence of NADPH-d reactivity in SC and shows that NADPH-d histochemistry is a useful tool for peripheral nerve biopsies study.

Diphtheria↗

PubMed2000

Studies of isopenicillin N synthase enzymatic properties using a continuous spectrophotometric assay.

Isopenicillin N synthase (IPNS) from Aspergillus nidulans is a no-heme iron(II)-dependent oxygenase which catalyses, in a single reaction, the bicyclisation of delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine into isopenicillin N, the precursor of all other penicillins, cephalosporins and cephamycins. The IPNS reaction can be followed directly and continuously by a new assay which monitors the absorbance increase at 235 nm characteristic of penicillin nucleus formation. Using this assay, the effects of influential factors affecting the in vitro IPNS enzymatic reaction were investigated. Even under optimal conditions, enzyme inactivation occurred during catalysis. Iron(II) depletion and product inhibition were not the cause of this phenomenon, the addition of antioxidants or reducing agents failed to slow down inactivation or reactivate the enzyme. Therefore, this phenomenon appears to be irreversible and is attributed to oxidative damage caused to the enzyme by reactive oxygen species generated in solution during catalysis. Nevertheless, the steady-state kinetic parameters for the IPNS reaction were determined.

Antioxidants↗

PubMed1990

Differential effects of captopril and enalapril, two angiotensin converting enzyme inhibitors, on immune reactivity in experimental lupus disease.

We have previously demonstrated that Captopril, an inhibitor of angiotensin converting enzyme (ACE), ameliorates experimental systemic lupus erythematosus in inbred MRL lpr/lpr (MRL/l) mice. In contrast, Enalapril, another ACE inhibitor with antihypertensive properties but lacking a thiol group, did not show similar beneficial effects. To better understand the mode of action of captopril in the autoimmune disease we have evaluated its immunomodulatory properties with special emphasis on antigen-specific and polyclonal B- and T-cell activation. The results obtained strongly suggest that Captopril exerts its immunomodulatory effects through stimulation of T-lymphocytes.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1983

Soluble guanylate cyclase activation by nitric oxide and its reversal. Involvement of sulfhydryl group oxidation and reduction.

Pre-incubation of either crude or purified nitric oxide-stimulated soluble lung guanylate cyclase resulted in a temperature-dependent decay of enzyme activity. The decay of nitric oxide-stimulated activity during pre-incubation was associated with a reduced responsiveness of the enzyme to reactivation by a second exposure to nitric oxide. This loss of enzyme responsiveness to reactivation by nitric oxide was greater with purified guanylate cyclase than with the crude enzyme and was highly dependent upon the nitric oxide dose. The addition of dithiothreitol or other thiols to nitric oxide-stimulated enzyme markedly accelerated the decay of activity in a dose-dependent manner. In addition, thiols prevented the loss of responsiveness of guanylate cyclase to reactivation by nitric oxide. Nitric oxide-stimulated enzyme activity was, therefore, reversed by the addition of thiol reducing agents. The addition of the thiol oxidizing agents, diamide or oxidized glutathione, to nitric oxide-stimulated guanylate cyclase caused a rapid and irreversible loss of activity. The effects of diamide or oxidized glutathione on the crude enzyme were prevented by excess dithiothreitol. Dithiothreitol did not prevent the destruction of purified nitric oxide-stimulated guanylate cyclase activity by diamide or oxidized glutathione, however. The results suggest that nitric oxide activation and its reversal are linked to the reversible oxidation and reduction, respectively, of sulfhydryl groups on guanylate cyclase which are involved in enzyme activation. The results further suggest the existence of a second class of sulfhydryl groups involved in the maintenance of enzyme activity.

Animals↗

PubMed1987

Reversal of age-related effects in rat muscle phosphoglycerate kinase.

Rat muscle phosphoglycerate kinase is one of several enzymes in which age-related effects have been identified. Thus, samples of this enzyme isolated from old rats display a greatly increased heat stability as compared with enzyme isolated from young animals. Previous studies detected no differences in the sequence of amino acids or in the net charge between the young and old forms of the enzyme and it was concluded that the age-related structural modifications are purely conformational. The present study was conducted with the aim of critically testing this hypothesis. To this end, samples of phosphoglycerate kinase purified from skeletal muscle of young and old rats were unfolded by an 18-hr incubation in a 2 M guanidine hydrochloride solution at 4 degrees C, a treatment that results in extensive loss of the three-dimensional structure of the enzyme. A complete reactivation of both enzymes was achieved by dilution of the unfolded enzyme solutions into a large excess of denaturant-free buffer followed by 4 hr of incubation at 25 degrees C. The reactivation kinetics of the unfolded young and old enzymes were practically identical and the refolded products, compared using heat-inactivation kinetics as a sensitive probe, were found to be identical. Moreover, their heat inactivation coincided with that of young untreated phosphoglycerate kinase. These results demonstrate the reversibility of age-related effects at the molecular level and provide strong support for the hypothesis that the modifications in phosphoglycerate kinase in old muscle are purely conformational and, hence, clearly postsynthetic.

Aging↗

PubMed1989

Isolation and characterisation of the glycerol dehydrogenase from Bacillus stearothermophilus.

A protocol for the rapid purification of the glycerol dehydrogenase (glycerol: NAD+ 2-oxidoreductase, EC 1.1.1.6) from the thermophile Bacillus stearothermophilus has been developed using a combination of chromatographic techniques including affinity chromatography on a Sepharose-immobilised triazine dye (Procion red, HE3B, ICI). Substrate specificity has been examined and Km values determined. The protein has been shown to have an oligomeric Mr of approx. 180,000 and consists of four identical subunits of Mr 42,000. Exposure to chelating agents (e.g., EDTA) leads to total loss of activity; the EDTA-inactivated enzyme can be reactivated by Zn2+ and requires 1 mol equivalent of zinc per subunit for full catalytic activity. Other divalent cations such as Cd2+ and Co2+ will reactivate the apo-enzyme but yields an enzyme of lower specific activity. The enzyme binds 1 equivalent of NADH per subunit and during catalysis transfers the 4-pro-R hydride from the nicotinamide ring of the reduced-coenzyme to the substrate. Glycerol increases the dissociation constant for the interaction between NADH and Zn-metallo-glycerol dehydrogenase (ZnGDH) but has no effect on the equilibrium between NADH and metal-depleted enzyme.

Amino Acids↗

PubMed2003

Quantitative detection of C-reactive protein using phosphocholine-labelled enzyme or microspheres.

C-reactive protein (CRP) is a positive, acute-phase protein. Plasma levels rise dramatically in response to tissue injury or inflammation and fall rapidly after recovery or treatment. Antibody-based human CRP test systems do not readily detect CRP from other animals due to the species specificity of antibodies directed against human CRP. Thus, generic systems for CRP detection, based solely on the interaction between CRP and phosphocholine (PC), have been developed. PC-bovine serum albumin (PC-BSA) conjugates were produced and either labeled with horseradish peroxidase to facilitate CRP detection in a CRP enzyme-linked sorbent assay (ELSA) or coupled to carboxy-modified microspheres to facilitate the nonenzymatic, turbidimetric detection of CRP. The CRP-ELSA is a competitive assay, where the total assay time is 45 min, the assay sensitivity is 1.06 mg/L CRP, and the dynamic range of the assay is 0-500 mg/L. When PC-BSA conjugate is covalently coupled to carboxylated microspheres, agglutination occurs in the presence of CRP, the extent of which depends on the quantity of CRP present in the sample. Total assay time is 5 min with a dynamic range of 25-500 mg/L. Both assay formats are capable of accurately detecting human CRP and the CRP-ELSA can detect canine CRP as a disease state indicator.

Animals↗

PubMed1997

Oscillations in activities of enzymes in pancreatic islet subcellular fractions induced by physiological concentrations of effectors.

Glucose, the most potent insulin secretagogue, stimulates insulin secretion by aerobic glycolysis, but other secretagogues stimulate insulin release exclusively by mitochondrial metabolism. It is well known that in the intact pancreatic beta-cell, either kind of secretagogue can induce oscillations in metabolism (e.g., glycolysis, ATP/ADP, NAD(P)/NAD(P)H ratios) that occur with a periodicity similar to oscillations in membrane electrical potential and insulin secretion. In this study, pancreatic islet cytosol or mitochondrial fractions were incubated in the presence of physiological concentrations of substrates. Repeated additions of physiological effectors caused oscillations in the activities of the three enzymes studied. Succinate dehydrogenase activity in islet mitochondrial extracts was made to oscillate by adding oxaloacetate (5 micromol/l) to inhibit the enzyme. The enzyme was reactivated by adding acetyl-CoA (3 micromol/l), which combines with oxaloacetate in the citrate synthase reaction and lowers the concentration of oxaloacetate, thus beginning another oscillation. Pyruvate kinase activity was made to oscillate by adding fructose bisphosphate (10 micromol/l). Fructose bisphosphate was degraded to triose phosphates fairly rapidly, and, as it was degraded, there was a parallel decrease in pyruvate kinase activity. The enzyme was reactivated and made to oscillate with subsequent additions of fructose bisphosphate. The mitochondrial glycerol phosphate dehydrogenase was made to oscillate by adding EGTA to chelate calcium, which activates the enzyme. When the concentration of free calcium was raised to >0.1 micromol/l by adding more calcium, the activity of the enzyme increased. Repeated additions of chelator and calcium caused the enzyme activity to oscillate. The results with these three enzymes and physiological concentrations of naturally occurring effectors raise the possibility that the activities of not only these enzymes but of numerous enzymes oscillate in vivo in response to levels of allosteric effectors and substrates. If this is the case, pacemaker activity may result from complex effects distributed across multiple regulatory sites in both the cytosol and mitochondria, rather than from a single enzyme acting as a primary pacemaker.

Acetyl Coenzyme A↗

PubMed1975

Studies on sulfhydryl groups of Aspergillus niger amine oxidase.

Amino acid analysis of the amine oxidase of Aspergillus niger (monoamine:O2 oxidoreductase (deaminating), EC 1.4.3.4) showed a composition similar to that of bovine plasma enzyme. One molecule of enzyme contained 25 Cys residues. It was shown that 9 to 11 residues of Cys were titrated to be SH groups. The amine oxidase reaction was markedly inhibited by metal ions (Cu2+, Hg2+, Ag+). The enzyme was inactivated with SH reagents (phenyl mercuric acetate, Cl-HgBzO-) and the extent of this inactivation was dependent on the time of incubation with SH reagents. Also, the Cl-HgBzO- -inactivated enzyme was reactivated with cysteine and this reactivation was biphasic with the time of incubation. The Cl-HgBzO--inactivated amine oxidase was compared with the native enzyme in their reactivity with phenylhydrazine and their spectral properties. The results showed that the Cl-HgBzO--inactivated enzyme had lower reactivity with phenylhydrazine than the native enzyme and had higher absorbance values than the native enzyme around 400 nm wavelengths.

Amino Acids↗

PubMed1974

RNA polymerase assembly in vitro. Temperature dependence of reactivation of denatured core enzyme.

The Escherichia coli RNA polymerase core molecule, after denaturation in 6 M guanidine hydrochloride, can be completely reactivated in the absence of sigma subunit. Reactivation is temperature dependent. At 4 degrees a renatured-inactive preparation is formed that has most of the secondary structure of the original native molecule but has a reduced sedimentation coefficient and a smaller Stokes radius and is, therefore, of lower molecular weight. Upon warming to 37 degrees the renatured-inactive preparation is converted in a time-dependent process to the renatured-active preparation, which has the same amount of secondary structure and same molecular weight as native RNA polymerase. Since the renatured-inactive material is probably composed of subunit assemblies and can be readily reactivated, it should be useful for studying the subunit interactions and control of assembly of RNA polymerase.

Binding Sites↗

PubMed1984

Reactivation of human placental 17 beta, 20 alpha-hydroxysteroid dehydrogenase: affirmation of affinity labeling principles.

Human placental 17 beta, 20 alpha-hydroxysteroid dehydrogenase was completely inactivated by the affinity alkylator, 3-bromoacetoxy-1,3,5(10)-estratrien-17-one (estrone 3-bromoacetate). The inactivated enzyme was then reactivated to 100% of the enzyme activity by base-catalyzed hydrolysis of the steroidalester-enzyme conjugate. After the reactivated enzyme was repurified by dialysis, re-inactivation studies were performed on it. The reactivated enzyme could not be re-inactivated by the original alkylator, estrone 3-bromoacetate. However, 16 alpha-bromoacetoxyestradiol-17 beta 3-methyl ether caused a loss of reactivated enzyme activity at a rate comparable to that for the native enzyme. These observations demonstrate that a specific amino acid modification within the enzyme active site was produced by estrone 3-bromoacetate alkylation and suggest that the conformation of the active center was essentially unaltered. Thus, these successful reactivation studies of 17 beta, 20 alpha-hydroxysteroid dehydrogenase affirm the specificity of affinity labeling. This methodology also offers a new tool to investigate the steroid binding regions of macromolecular proteins.

20-Hydroxysteroid Dehydrogenases↗

PubMed1997

A shared subunit belongs to the eukaryotic core RNA polymerase.

The yeast RNA polymerase I is a multimeric complex composed of 14 distinct subunits, 5 of which are shared by the three forms of nuclear RNA polymerase. The reasons for this structural complexity are still largely unknown. Isolation of an inactive form of RNA Pol I lacking the A43, ABC23, and A14 subunits (RNA Pol I delta) allowed us to investigate the function of the shared subunit ABC23 by in vitro reconstitution experiments. Addition of recombinant ABC23 alone to the RNA Pol I delta reactivated the enzyme to up to 50% of the wild-type enzyme activity. The recombinant subunit was stably and stoichiometrically reassociated within the enzymatic complex. ABC23 was found to be required for the formation of the first phosphodiester bond, but it was not involved in DNA binding by RNA Pol I, as shown by gel retardation and surface plasmon resonance experiments, and did not recycle during transcription. Electron microscopic visualization and electrophoretic analysis of the subunit depleted and reactivated forms of the enzyme indicate that binding of ABC23 caused a major conformational change leading to a transcriptionally competent enzyme. Altogether, our results demonstrate that the ABC23 subunit is required for the structural and functional integrity of RNA Pol I and thus should be considered as part of the core enzyme.

DNA↗

PubMed2005

Prevention of naphthalene-induced pulmonary toxicity by glutathione prodrugs: roles for glutathione depletion in adduct formation and cell injury.

Naphthalene is metabolized in the lung and liver to reactive intermediates by cytochrome P450 enzymes. These reactive species deplete glutathione, covalently bind to proteins, and cause necrosis in Clara cells of the lung. The importance of glutathione loss in naphthalene toxicity was investigated by using the glutathione prodrugs (glutathione monoethylester or cysteine-glutathione mixed disulfide) to maintain glutathione pools during naphthalene exposure. Mice given a single intraperitoneal injection of naphthalene (1.5 mmol/kg) were treated with either prodrug (2.5 mmol/kg) 30 min later. Both compounds effectively maintained glutathione levels and decreased naphthalene-protein adducts in the lung and liver. However, cysteine-glutathione mixed disulfide was more effective at preventing Clara cell injury. To study the prodrugs in Clara cells without the influence of hepatic naphthalene metabolism and circulating glutathione, dose-response and time-course studies were conducted with intrapulmonary airway explant cultures. Only the ester of glutathione raised GSH in vitro; however, both compounds limited protein adducts and cell necrosis. In vitro protection was not associated with decreased naphthalene metabolism. We conclude that (1) glutathione prodrugs can prevent naphthalene toxicity in Clara cells, (2) the prodrugs effectively prevent glutathione loss in vivo, and (3) cysteine-glutathione mixed disulfide prevents naphthalene injury in vitro without raising glutathione levels.

Animals↗

PubMed1995

S-methyl N,N-diethylthiocarbamate sulfone, a potential metabolite of disulfiram and potent inhibitor of low Km mitochondrial aldehyde dehydrogenase.

Disulfiram inhibits hepatic aldehyde dehydrogenase (ALDH) causing an accumulation of acetaldehyde after ethanol ingestion. It is thought that disulfiram is too short-lived in vivo to directly inhibit ALDH, but instead is biotransformed to reactive metabolites that inhibit the enzyme. S-Methyl N,N-diethylthiocarbamate (MeDTC) sulfoxide has been identified in the blood of animals given disulfiram and is a potent inhibitor of ALDH (Hart and Faiman, Biochem Pharmacol 46: 2285-2290, 1993). MeDTC sulfone is a logical metabolite of MeDTC sulfoxide. Therefore, we investigated the effects of MeDTC sulfone on the activity of rat hepatic low Km mitochondrial ALDH, the major enzyme in the metabolism of acetaldehyde. MeDTC sulfone inhibited the low Km mitochondrial ALDH in vitro with an IC50 of 0.42 +/- 0.04 microM (mean +/- SD, N = 5) compared with disulfiram, which had an IC50 of 7.5 +/- 1.2 microM under the same conditions. The inhibition of ALDH by MeDTC sulfone was time dependent. The decline in ALDH activity followed pseudo first-order kinetics with an apparent half-life of 2.1 min at 0.6 microM MeDTC sulfone. Inhibition of ALDH by MeDTC sulfone was apparently irreversible; dilution of the inhibited enzyme did not restore lost activity. The substrate (acetaldehyde, 80 microM) and cofactor (NAD, 0.5 mM) together completely protected ALDH from inhibition by MeDTC sulfone; substrate alone partially protected the enzyme. Addition of either thiol-containing compound glutathione (GSH) or dithiothreitol (DTT) to MeDTC sulfone before incubation with the enzyme increased the IC50 of MeDTC sulfone by 7- to 14-fold. Neither GSH nor DTT could restore lost ALDH activity after exposure of the enzyme to MeDTC sulfone. Results of these studies indicate that MeDTC sulfone, a potential metabolite of disulfiram, is a potent, irreversible inhibitor of low Km mitochondrial ALDH.

Aldehyde Dehydrogenase↗

PubMed2000

Cloning, expression, and characterization of human cytosolic aminopeptidase P: a single manganese(II)-dependent enzyme.

The mammalian bradykinin-degrading enzyme aminopeptidase P (AP-P; E. C. 3.4.11.9) is a metal-dependent enzyme and is a member of the peptidase clan MG. AP-P exists as membrane-bound and cytosolic forms, which represent distinct gene products. A partially truncated clone encoding the cytosolic form was obtained from a human pancreatic cDNA library and the 5' region containing the initiating Met was obtained by 5' rapid accumulation of cDNA ends (RACE). The open reading frame encodes a protein of 623 amino acids with a calculated molecular mass of 69,886 Da. The full-length cDNA with a C-terminal hexahistidine tag was expressed in Escherichia coli and COS-1 cells and migrated on SDS-PAGE with a molecular mass of 71 kDa. The expressed cytosolic AP-P hydrolyzed the X-Pro bond of bradykinin and substance P but did not hydrolyze Gly-Pro-hydroxyPro. Hydrolysis of bradykinin was inhibited by 1,10-phenanthroline and by the specific inhibitor of the membrane-bound form of mammalian AP-P, apstatin. Inductively coupled plasma atomic emission spectroscopy of AP-P expressed in E. coli revealed the presence of 1 mol of manganese/mol of protein and insignificant amounts of cobalt, iron, and zinc. The enzymatic activity of AP-P was promoted in the presence of Mn(II), and this activation was increased further by the addition of glutathione. The only other metal ion to cause slight activation of the enzyme was Co(II), with Ca(II), Cu(II), Mg(II), Ni(II), and Zn(II) all being inhibitory. Removal of the metal ion from the protein was achieved by treatment with 1,10-phenanthroline. The metal-free enzyme was reactivated by the addition of Mn(II) and, partially, by Fe(II). Neither Co(II) nor Zn(II) reactivated the metal-free enzyme. On the basis of these data we propose that human cytosolic AP-P is a single metal ion-dependent enzyme and that manganese is most likely the metal ion used in vivo.

Amino Acid Sequence↗

PubMed1978

Effects of proteolytic enzymes and neuraminidase on the I and i erythrocyte antigen sites. Quantitative and thermodynamic studies.

The effects of neuraminidase and proteolytic enzymes on I and i reactivities was studied with I and i adult red cells, using radioimmunological methods. An enhanced reactivity after enzyme treatment is not exclusively due to a membrane charge reduction. The increase in site numbers and association constants bring about the gain of the cold agglutinin fixation. The release of N-acetylneuraminic acid residues gradually increases the I antigen site density of I red cells and the i site density of i red cells. Similar behaviour was observed after proteolytic enzyme treatment with papain, bromelin or ficin. The proteolytic treatment of I erythrocyte reveals underlying i receptors on these cells. Following membrane glycoprotein chain removal, anti-i antibodies are specifically fixed on I erythrocytes. The accessibility to antibodies of the determinants responsible for I and i erythrocyte activities was influenced significantly by steric hindrance factors. While N-acetylneuraminic acid release increased antibody affinities for the antigenic receptor, the removal of glycopeptide chains greatly diminished steric hindrance and brought about higher affinity constants. After enzyme treatment, the antigenic structures become more homogeneous in their reaction with antibodies. The heterogeneity of binding constants observed with antigenic determinants of non-treated erythrocytes is probably due to the wide range of spatial distribution of these receptors within the membrane.

Adult↗

PubMed2005

Bifidobacterial lipoglycan as a new cause for false-positive platelia Aspergillus enzyme-linked immunosorbent assay reactivity.

We previously hypothesized that a lipoglycan of Bifidobacterium bifidum subsp. pennsylvanicum cross-reacts with the Platelia Aspergillus (PA) enzyme-linked immunosorbent assay (ELISA) based on the presence of galactofuranosyl epitopes in the cell wall (M. A. S. H. Mennink-Kersten, R. R. Klont, A. Warris, H. J. M. Op den Camp, and P. E. Verweij, Lancet 363:325-327, 2004). We tested this hypothesis by testing bacterial suspensions of different bifidobacterial species and other gram-positive and -negative bacteria with the PA ELISA, which is used to detect circulating galactomannan for the serodiagnosis of invasive aspergillosis. Furthermore, neonatal fecal samples were enumerated for bifidobacteria by fluorescence in situ hybridization (FISH) and tested for PA ELISA reactivity. All bifidobacteria, except B. infantis and B. adolescentis, showed reactivity 6- to 600-fold higher compared to the controls (i.e., Micrococcus luteus and Propionibacterium freudenreichii, which contain a cell wall lipomannan). Eggerthella lenta showed a 25-fold-higher reactivity. ELISA reactivity was clearly shown to be associated with bacterial lipoglycans containing a beta-1,5-galactofuranosyl chain. All neonatal feces showed PA ELISA reactivity and associated numbers of bifidobacteria. Since high concentrations of bifidobacteria are present in the human gut, these bacteria or excreted lipoglycan may cause false serum PA ELISA reactivity in selected patient groups, especially neonates.

Antigens, Fungal↗

PubMed1991

Diabetes is associated with a high incidence of endothelial-binding antibodies which do not correlate with retinopathy, von Willebrand factor, angiotensin-converting enzyme or C-reactive protein.

Increasing evidence implicates endothelial cell dysfunction in the development of diabetic microvascular disease, but its precise nature is elusive. This study sought to extend previous observations on the association between diabetes and the endothelial cell-derived glycoprotein von Willebrand factor (vWF), in a study of 777 diabetic patients. Compared with a mean of 1.07 +/- 0.18 iu/ml in a non-diabetic population, vWF was found to be elevated to 1.59 +/- 0.14 iu/ml in the whole sample, but particularly in those with retinopathy or microalbuminuria. It was studied whether such an elevation is part of an acute phase response, or is accompanied by other indicators of endothelial cell dysfunction. Plasma samples were examined for vWF, and serum for angiotensin converting enzyme (ACE), C-Reactive protein (CRP), IgG and IgM endothelial cell-binding antibodies (anti-EC Ig). A strong positive association was found (p less than 0.005) between the extent of elevation of vWF and the presence of diabetic retinopathy. ACE and CRP were rarely raised, and their levels did not correlate with either diabetic retinopathy or vWF levels. However, 52% of the patients had circulating anti-EC IgG or IgM, although their presence did not correlate with retinopathy, or with vWF, ACE or CRP. Thus diabetic retinopathy and probably nephropathy is associated with a specific but generalised disturbance of vascular endothelial cell function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗