Search PubMed⌕ Search

Biomedical subjects

D H Bing

Publications and source records attributed to D H Bing.

At least 37 records · Page 2Linked to original sources
PubMed1985

Variability in purified dysfunctional C1(-)-inhibitor proteins from patients with hereditary angioneurotic edema. Functional and analytical gel studies.

C1(-)-inhibitor (C1(-)-INH) proteins from normal persons and members of eight different kindred with dysfunctional C1(-)-INH proteins associated with hereditary angioneurotic edema (HANE) were compared with respect to their inhibitory activity against purified preparations of C1s-, plasma kallikrein, activated forms of Hageman factor, and plasmin. Each dysfunctional C1(-)-INH protein showed a unique spectrum of inhibitory activity against these enzymes. Although none of the dysfunctional C1(-)-INH proteins significantly impaired amidolysis by plasmin, all but one inhibited activated Hageman factor. One purified dysfunctional C1(-)-INH (Ta) inhibited purified C1s- to a normal degree. Another C1(-)-INH (Za) had almost seven times as much inhibitory activity as normal C1(-)-INH against activated Hageman factor, but had decreased activity against C1s- and no activity against plasmin. Analyses of mixtures of plasmin and C1(-)-INH proteins in SDS gel electrophoresis revealed variability in the patterns of complex formation and cleavage of dysfunctional proteins after exposure to C1s- and plasmin. Some bound to plasmin and were cleaved, even though none significantly impaired the amidolytic activity of plasmin. Two were cleaved by C1s-, whereas neither normal or other dysfunctional C1(-)-INH were cleaved. Dysfunctional C1(-)-INH proteins from patients with HANE are thus heterogeneous in their inhibitory properties and there must be different structural requirements for the inhibition of the various plasma enzymes that can be regulated by normal C1(-)-INH. The data suggest that in addition to common sites of interactions between these proteases and C1(-)-INH, there are also points of contact that are specific for each protease. Genetic mutations leading to structural changes at some of these sites may have differing effects on the interaction between individual proteases and abnormal C1(-)-INH proteins. These alterations may allow these proteins to serve as probes for structural requirements for inhibitory actions of normal C1(-)-INH.

Angioedema↗
PubMed1984

Complement interaction with immune serum globulin and immune globulin intravenous.

Three complement assays, C1q binding activity, C3 activation in normal human serum, and enhancement of alternative pathway activity, have been used to evaluate the in vitro anticomplementary activity of untreated and heat-aggregated (63 degrees C, 10 minutes) immune serum globulin and immune globulin intravenous prepared by partial reduction and alkylation. Unheated immune globulin intravenous marginally activated endogenous C3 in normal serum, had a fivefold lower affinity for 125I C1q but was very similar to immune serum globulin in enhancing complement alternative pathway activity. Heat-aggregated immune globulin intravenous was about twofold less effective than heat-aggregated immune serum globulin in the activation of C3 in normal serum and had approximately a threefold lower affinity for 125I C1q. The ability of immune globulin intravenous to retain specific complement receptor activity suggests that it would also retain in vivo efficacy in complement-mediated amplification of host defense reactions but that it is safe for intravenous use due to a lower capacity to initiate nonspecific complement activation.

Complement Activating Enzymes↗
PubMed1983

The binding properties of human complement component C1q. Interaction with mucopolysaccharides.

Quantitative measurements have been made of the interaction of human complement subcomponent C1q with mucopolysaccharides. The binding of C1q to heparin was quantitatively examined by utilizing an assay that employs a 125I-labeled low molecular weight heparin glycosaminoglycan (LMW-Hep) (Mr = 8500). Two classes of binding sites were detected. The first class of sites bound 2.02 mol of LMW-Hep/mol of C1q with a Kd of 76.6 nM. The second class of sites complexes with 12 mol of LMW-Hep with a Kd of 1.01 microM. The higher affinity-binding site for LMW-Hep could be assigned to the collagenous region of C1q (C1q-c); 2.2 mol of 125I-LMW-Hep were bound/mol of purified isolated C1q-c with a Kd = 381 nM. In contrast, the isolated C1q globular region did not bind to 125I-LMW-Hep. The binding of LMW-Hep to C1q and the C1q-c region was confirmed by fluorescence polarization experiments; C1q and C1q-c bound 2.3 and 2.02 mol of fluorescamine-labeled LMW-Hep/mol of protein, respectively. A variety of mucopolysaccharides were able to inhibit interaction of C1q with 125I-LMW-Hep, the most effective being heparan sulfate and dermatan sulfate. LMW-Hep (2.5 nM) inhibited the ability of C1q (0.5 nM) to recombine with C1r (1.4 nM) and C1s (1.6 nM) to form hemolytically active C1. At 250 mM, LMW-Hep inhibited the hemolytic activity of reconstituted C1. The ability of mucopolysaccharides to interact with purified C1q suggests a role for such molecules in the regulation of the first component of complement.

Centrifugation, Density Gradient↗
PubMed1983

The interaction of immune serum globulin and immune globulin intravenous with complement.

The in vitro anticomplementary activity of untreated and heat-aggregated (63 degrees C, 10 min) immune serum globulin (ISG) and immune globulin intravenous (IGIV) prepared by partial reduction and alkylation have been evaluated by three assays, C3 activation, binding to C1q and enhancement of alternative pathway lysis of rabbit erythrocytes. Crossed immunoelectrophoresis was used to quantitatively measure the ability of ISG and IGIV to activate endogenous C3 in normal serum. Binding to C1q was determined according to the ability to inhibit binding of 125I-C1q to solid phase IgG. ISG and IGIV enhancement of lysis of rabbit erythrocytes by normal human serum adsorbed with rabbit erythrocytes in the presence of MgEGTA was used to determine activity in the alternative complement pathway. Unheated IGIV at 10 mg/ml only marginally activated endogenous C3 in normal serum, had about a 5-fold lower affinity for 125I-C1q (Ki = 138 to 356 microM vs Ki = 62.5 microM for ISG), but was very similar in ability to ISG on a weight basis in enhancing complement alternative pathway activity (RCH50 = 0.23 to 0.40 mg for IGIV vs 0.17 mg for ISG). Heat-aggregated IGIV at 5 mg/ml in normal human serum was about 2-fold less effective than heat-aggregated ISG in the activation of C3 in normal serum and had approximately 2- to 3-fold lower affinity in the C1q binding assay (Ki = 45 to 83 nM for heat-aggregated IGIV vs Ki = 14.6 nM for heat-aggregated ISG). These data suggest that IGIV prepared by chemical modification retains sufficient specific receptor activity to allow in vivo efficacy in complement-mediated amplification of host defense reactions, but is safe for intravenous use due to a lower capacity to initiate nonspecific complement activation.

Complement Activating Enzymes↗
PubMed1983

Pathophysiology and immunology of the Jarisch-Herxheimer-like reaction in louse-borne relapsing fever: comparison of tetracycline and slow-release penicillin.

Twelve men with louse-borne relapsing fever were treated with single doses of procaine penicillin plus aluminum monostearate (PAM) intramuscularly or of tetracycline intravenously. All patients experienced a definite Jarisch-Herxheimer-like reaction. Fever and spirochetemia were significantly prolonged and peak temperature was lower and occurred later in the PAM-treated group. Peak pulmonary ventilation, metabolic rate, and arterial PO2 were significantly higher in the tetracycline-treated group. Circulatory changes were similar in the two groups but were prolonged in the PAM-treated patients. Thus, tetracycline is recommended for treatment because it is more rapidly effective in eliminating Borrelia spirochetes and produces a reaction no more stressful physiologically than the one after PAM. There was no evidence of complement activation, and there was no change in immunoglobulin levels throughout the reaction. Immune complexes were detected in serum of five patients before treatment, but in fewer patients at the peak of the reaction and subsequently.

Adult↗
PubMed1982

Computer-generated models of blood coagulation factor Xa, factor IXa, and thrombin based upon structural homology with other serine proteases.

Computer-generated molecular models of the trypsin-like domains of blood coagulation factor IXa, Factor Xa, and thrombin have been prepared. These hypothetical models are based upon the sequence homology of the blood coagulation enzymes with the pancreatic serine proteases and the known three-dimensional structure of the pancreatic serine proteases. The internal structures and active sites of these enzymes are highly conserved. The high degree of substrate specificity which characterizes the blood coagulation enzymes appears to be defined not entirely by the active site, but by the unique molecular surface surrounding the active site of each enzyme. Several regions which demonstrate high sequence variability among these enzymes likely participate in forming the putative extended substrate binding sites.

Amino Acid Sequence↗
PubMed1982

Fibronectin interacts with Clq, a subcomponent of the first component of complement.

Human Clq, a subcomponent of the first component of complement interacts with human fibronectin. Using ELISA methodology fixation of Clq to solid phase fibronectin, as well as fibronectin to solid phase Clq has been demonstrated. Cl in its native macromolecular form displays little reactivity for fibronectin, nor does Cl reconstituted from Clq, Clr and Cls in the presence of Ca2+ ions. Heating of Clq above its thermal transition temperature (51 degrees C) induces an increased binding capacity for fibronectin. On the other hand, a mixture of the dissociated A, B and C chains of Clq is less active than native Clq. The binding of fibronectin appears to be mediated by the A chain. Studies with Clq deprived of its globular parts by peptic digestion indicate that the collagen-like regions of Clq are involved in fibronectin binding. In contrast, collagenase treatment of Clq abrogates its fibronectin binding capacity.

Animals↗
PubMed1982

Fibronectin binds to the C1q component of complement.

Fibronectin immobilized to plastic tubes binds soluble C1q with a Kd of 82 +/- 2.6 nM. The binding of fibronectin to C1q is relatively insensitive to pH but is sensitive to ionic conditions. C1q covalently bound to Sepharose selectively binds cellular fibronectin produced by a hamster fibroblast cell line. The globular head regions of C1q have no effect on the binding of C1q to fibronectin but the collagenous tails of C1q interfere competitively with a Ki of 59 nM. We conclude that fibronectin binds C1q via its collagen-like tail region and thus the process resembles the binding of fibronectin to gelatin. This is further emphasized by our observation that gelatin binds to fibronectin immobilized on plastic tubes with a Kd of 131 nM. Because fibronectin stimulates endocytosis in several systems and promotes the clearance of particulate material from the circulation, these results suggest the possibility that fibronectin could function in the clearance of C1q-coated material such as immune complexes or cellular debris.

Animals↗
PubMed1981

Photoaffinity inhibition of rat liver NAD(P)H dehydrogenase by 3-(alpha-acetonyl-p-azidobenzyl)-4-hydroxycoumarin.

NAD(P)H dehydrogenase was purified in four steps from a homogenate of rat liver. The final step was affinity chromatography on Sepharose coupled to 3,3'-(m-hydroxybenzylidene)bis(4-hydroxycoumarin). The purified enzyme was inhibited competitively with respect to NADH by 3-(alpha-acetonyl-p-nitrobenzyl)-4-hydroxycoumarin (acenocoumarin) (Ki = 1.7 microM). The acenocoumarin was converted into an azide which was used to photoaffinity inhibit the enzyme. Following photolysis in the presence of the azide, the enzyme was inactivated in proportion to the concentration of azide present during irradiation. A maximum of 35-40% inhibition could be achieved by a single irradiation at 254 nm for 1.5 min. This inhibition was noncompetitive with respect to NADH. The inactivation was shown to be specific as acenocoumarin afforded complete protection against inactivation, irradiation was required to achieve inactivation, and the enzyme was unaffected by irradiation alone.

Acenocoumarol↗
PubMed1981

A computer-generated three-dimensional model of the B chain of bovine alpha-thrombin.

A computer graphic molecular display system has been used to construct a three-dimensional model of the B chain of bovine thrombin. The model is derived from the bovine alpha-chymotrypsin structure as determined by X-ray crystallographic studies. The amino acid sequence of bovine thrombin has been substituted for that of alpha-chymotrypsin, preserving the beta-barrel structure and maximizing homology of the amino acid sequence of the two proteins. With the exception of an area in the vicinity of the specificity binding pocket, most of the changes observed in thrombin occur on the surface of the molecule. The most notable changes observed in the model are the increases on the surface of positively charged (arginine and lysine) and negatively charged (glutamate and aspartate) residues. A glutamate replaces methionine 192 near the entrance to the specificity binding pocket. The nature of this site was further altered by the substitution of an aspartate for serine 189 and an alanine for serine 190. The structure of the resulting specificity binding pocket is consistent with that of serine proteases, which have trypsin-like substrate specificity. The computer graphics molecular display system has been used to insert models of synthetic thrombin inhibitors into the active site of the thrombin B chain model. With the model, it has been possible to correlate the interaction of thrombin with the observed binding constants of two inhibitors of trypsin-like serine proteases, p-amidinophenylmethylsulfonylfluoride (Ki = 1.27 x 10(-6) M) and m-[m-(trifluoromethyl)phenoxypropoxy]benzamidine (KD = 2.9 x 10(-6) M).

Amino Acids↗
PubMed1980

(p-Amidinophenyl)methanesulfonyl fluoride, an irreversible inhibitor of serine proteases.

p-(Amidinophenyl)methanesulfonyl fluoride (p-APMSF) has been synthesized and shown to be a specific, irreversible inhibitor of the class of plasma serine proteases which demonstrate substrate specificity for the positively charged side chains of the amino acid lysine or arginine. In equimolar concentration, this compound causes immediate and complete irreversible inhibition of bovine trypsin and human thrombin. A 5-10-fold molar excess of reagent over enzyme is required to achieve complete irreversible inhibition of bovine Factor Xa, human plasmin, human C1-r, and human C1-s. the Ki of p-APMSF for all of the above-mentioned proteases is between 1 and 2 microM. In contrast, p-APMSF in large molar excess does not inactivate chymotrypsin or acetylcholinesterase. The unique reactivity of p-APMSF has been further shown in comparison with the related compound p-nitrophenyl (p-amidinophenyl)methanesulfonate which is an active-site titrant for thrombin but reacts poorly with Factor Xa, C1-r, and C1-s and is not hydrolyzed by bovine trypsin or human plasmin. Similarly, (p-amidinophenyl)methanesulfonate has a Ki of 30 microM for thrombin but is a poor inhibitor of trypsin, Factor Xa, C1-r, C1-s, and plasmin. Studies with bovine trypsin have demonstrated that the inhibitory activity of p-APMSF is the result of its interaction with the diisopropyl fluorophosphate reactive site. The unique reactivity of this inhibitor classifies it as one of the most effective active site directed reagents for this class of serine proteases. Collectively, these results suggest that the primary substrate binding site of these enzymes, which share a high degree of structural homology, do in fact significantly differ from each other in their ability to interact with low molecular weight inhibitors and synthetic substrates.

Models, Molecular↗