Mechanisms of activation of C'1 esterase in hereditary angioneurotic edema plasma in vitro.

The generation of C'1 esterase activity in siliconed plasma obtained from individuals with hereditary angioneurotic edema in remission tends to occur spontaneously, but can be hastened during its incubation with preparations of activated Hageman factor. This effect of activated Hageman factor could not be shown during its incubation with normal siliconed plasma, nor could consumption of normal serum inhibition of C'1 esterase be clearly shown. Soy bean trypsin inhibitor and heparin could impair this enhanced generation of C'1 esterase but neither inhibits the esterolytic function of C'1 esterase once formed. Trasylol was less effective in blocking this effect of activated Hageman factor. While the mechanism of the effect of activated Hageman factor upon C'1 activation remains obscure, it is apparent that some intermediate steps, possibly involving a kinin-forming system of plasma, may play a role.

Studies on the prekallikrein (kallikreinogen)--kallikrein enzyme system of human plasma. II. Evidence relating the kaolin-activated arginine esterase to plasma kallikrein.

Evidence is presented in this paper that the kaolin-activated arginine esterase of plasma is related to plasma kallikrein activity. Such a relationship is based on studies that (1) establish a constant ratio of esterase activity on various synthetic substrates for the kaolin-activated arginine esterase, purified kallikrein(s), and preparations obtained during the fractionation procedure; (2) exclude other known plasma and tissue arginine esterases; (3) confirm the requirement for factor XII in the activation of the enzyme precursor; and (4) show similarities in behavior between the plasma esterase and purified kallikrein(s) toward a variety of inhibitors. Based on this probable identification, evidence is provided that the concentration of active factor XII determines the rate of activation of plasma kallikreinogen, and that the activation may be blocked by polybrene. Once activated, plasma kallikrein is rapidly inactivated by the naturally occurring plasma inhibitor, but the inhibition is incomplete. Acid or chloroform treatment of plasma rapidly inactivates the plasma inhibitor without affecting the concentration of plasma kallikreinogen. Another plasma arginine esterase with properties suggestive of permeability factor is activated by factor XII in the presence of synthetic substrates, but only at low ionic strength. The data suggest that this enzyme is closely related to plasma kallikrein and that it arises from a common precursor.

Cholesterol ester hydrolase in human red blood cells.

1. Cholesterol ester hydrolytic activity (sterol-ester hydrolase EC 3.1.1.13) was detected in human red blood cells. Enzyme activity appeared confined to the cell membrane and was most marked in washed preparations of red cell ghosts. 2. Hydrolytic activity was stimulated by the anti-oxidants D-alpha-tocopherol and butylated hydroxytoluene. Marked inhibition was produced by erythrocyte hemolysate, sodium taurocholate, and Triton X-100. 3. Optimal pH for the reaction was 5.4--5.7. 4. Because red cell cholesterol is all unesterified, it is speculated that the hydrolase serves to maintain the erythrocyte membrane free of esterified cholesterol.

Pomegranate juice consumption reduces oxidative stress, atherogenic modifications to LDL, and platelet aggregation: studies in humans and in atherosclerotic apolipoprotein E-deficient mice.

BACKGROUND: Dietary supplementation with nutrients rich in antioxidants is associated with inhibition of atherogenic modifications to LDL, macrophage foam cell formation, and atherosclerosis. Pomegranates are a source of polyphenols and other antioxidants. OBJECTIVE: We analyzed, in healthy male volunteers and in atherosclerotic apolipoprotein E-deficient (E(0)) mice, the effect of pomegranate juice consumption on lipoprotein oxidation, aggregation, and retention; macrophage atherogenicity; platelet aggregation; and atherosclerosis. DESIGN: Potent antioxidative effects of pomegranate juice against lipid peroxidation in whole plasma and in isolated lipoproteins (HDL and LDL) were assessed in humans and in E(0) mice after pomegranate juice consumption for

Activation of arginine and tyrosine esterase in serum from patients with hereditary angio-oedema.

1. The role of clotting factor XII in the activation of the complement subunit C1s to C1 esterase was examined.2. In sera from patients with hereditary angio-oedema who lack the alpha(2)-glycoglobulin C1 inhibitor, silicates and other potent activators of clotting factor XII induced far less C1 esterase activity than did the weaker factor XII activators, carrageenin and cellulose sulphate. In contrast, the intensity of the induced plasma kallikrein activity corresponded more closely to the clot-promoting effect of the factor XII activators.3. Spontaneous generation of C1 esterase activity was only slightly delayed in hereditary angio-oedema sera previously depleted of factor XII. In normal sera, C1 esterase did not develop spontaneously and could not be induced.4. Experiments with inhibitors suggested that the spontaneous activation of C1s may consist of two phases: factor XII and other plasma proteases first activate small amounts of C1s; the resulting C1 esterase then activates the bulk of C1s. The observed spontaneous activation suggests that when fully activated, the C1s present in 1 ml of human serum will hydrolyse 1-2 mumol of ATEe/minute.

In vitro properties of diffuse cytoplasmic esterase-positive canine mononuclear leukocytes.

Depletion of cytoplasmic esterase-positive canine peripheral blood monocytes from mononuclear cell suspensions was attempted using plastic adherence, carbonyl iron ingestion and/or Sephadex G-10 filtration. An esterase-positive, nonadherent, nonphagocytic subpopulation was identified and further characterized by the presence or absence of cell membrane receptors for the Fc portions of immunoglobulin and the activated third component of complement. The majority of these nonadherent cells lacked these receptors. The data suggests that canine peripheral blood monocytes are a heterogenous cell population.

Rapid changes in surface antigen expression by blood monocytes cultured in suspension or adherent to plastic.

Cell surface antigens used as markers of in vivo differentiation may not be stable on monocytes maintained under different conditions of in vitro culture. Monocytes were isolated from blood by centrifugation over Percoll or by adherence to plastic dishes, and the cells cultured in suspension or as adherent monolayers. Initially, monocytes obtained by both methods were similar in size, morphology, and surface antigen expression detected with the antimonocyte monoclonal antibodies OKM1, FMC17, PHM2, and PHM3. After culture, cells maintained in suspension were predominantly small, whereas those adherent to plastic rapidly increased in size; however, cytochemical staining for nonspecific esterase and acid phosphatase showed increased enzymic activity by monocytes in both systems, possibly reflecting increased cell maturation. The most striking difference was a substantial loss of FMC17 antigen by most monocytes within four hours in suspension culture, as compared with a qualitative and quantitative increase in expression by plastic adherent cells within two hours. These changes occurred even if the cells were first reacted with lipopolysaccharide. Monocytes taken from suspension culture and allowed to adhere to plastic rapidly synthesized the antigen, a process inhibited by cycloheximide, and conversely, cells removed from plastic progressively displayed decreased FMC17 antigen expression when transferred to suspension culture. No functional role in adherence or phagocytosis has been found for the FMC17 antigen. The results suggest that antigen expression may depend as much on the physical state of the cells as on apparent activation or maturation events.

Serum esterase activity during the surgical therapy of bronchogenic carcinoma.

Serum esterase activity was estimated in 148 patients with bronchogenic carcinoma and in 19 patients with pulmonary tuberculosis before operation, 1 week and 3 weeks after operation. We failed to prove significant differences between the patients with malignant and nonmalignant lung diseases. We failed also to prove significant differences between the mean esterase activity findings regarding to the extent of surgery. They were identical even of the performed thoracotomy was radical, palliative or explorative. The course of changes in esterase activity findings is quite individual. From the esterase activity we cannot conclude, if the tumor tissue was completely removed or not.

Differential effect of the serine protease inhibitor phenyl methyl sulfonyl fluoride on cytochemically detectable esterases in human leucocytes and platelets.

Esterases of human leucocytes and platelets were studied by cytochemical methods. The aim of the study was to clarify the cellular distribution and possible nature of esterases types differing in their substrate specificity and/or their inhibitor sensitivity. 3 substrates (alpha-naphthyl acetate: ANA; naphthol AS-D chloroacetate: NASDCA; and N-acetyl DL-alanine alpha-naphthyl ester: NACALA) were used and the effects of 2 inhibitors (sodium fluoride and the serine protease inhibitor phenyl methyl sulfonyl fluoride: PMSF) were evaluated. 4 enzyme types were described: Type I, present in granulocytes, was detected using NASDCA and NACALA and was resistant to fluoride but sensitive to PMSF. Other types were detected using ANA as substrate. Type II, present in monocytes, was inhibited by both fluoride and PMSF. Type III, present in platelets and plasma cells, was inhibited by fluoride but resistant to PMSF. Type IV, present in lymphocytes, was resistant to both fluoride and PMSF. The specific aims and possible areas for application of these results are discussed.

Two esterases common to seminal plasma, other external secretions and leucocytes in man.

Two esterases previously identified in seminal plasma, on the basis of their electrophoretic mobility, immunogenicity and sensitivity to organophosphorus esters were detected in various human external secretions and leucocyte extracts. alpha-Esterase was found to be abundant in urine and milk whereas this enzyme occurred in a low concentration in seminal plasma, leucocyte extract, cervical mucus and sweat. The concentration of betagamma-esterase was high in seminal plasma and leucocyte extract. The enzyme was present in small amounts in urine, milk, gastric juice, saliva, sputum, tears, cervical mucus and sweat.

Saturable in vitro metabolism of articaine by serum esterases. Does it contribute to the persistence of the local anesthetic effect?

BACKGROUND AND OBJECTIVES: The amide-type local anesthetic articaine is unique in that hydrolysis to articainic acid by serum esterases is its main metabolic pathway. The purpose of the present investigation was to study the concentration dependence of this pathway in vitro. METHODS: To unbuffered (pH 8.2) as well as phosphate-buffered (pH 7.4) heated serum samples were added various amounts of articaine in the range 10-300 micrograms/mL. Concentrations of articaine and articainic acid were measured by high-performance liquid chromatography after incubating the samples at 37 degrees C for intervals ranging from 5 minutes to 6 hours after addition of articaine. RESULTS: The in vitro metabolism of articaine was shown to undergo pH-dependent Michaelis-Menten kinetics, indicating saturation at higher substrate concentrations. The Michaelis constant K(m) was determined as 175 micrograms/mL and 22.1 micrograms/mL and the maximum reaction rate Vmax as 2.1 micrograms/mL/min and 0.17 microgram/mL/min at pH 8.2 and pH 7.2, respectively. These results support previous in vivo observations that suggest saturable articaine metabolism, indicated by higher articaine/articainic acid metabolic ratio with higher articaine concentrations in alveolar blood after dental extraction. CONCLUSION: Local saturation of the serum esterases may contribute to the advantageous relationship between persistence of the local anesthetic effect and low systemic toxicity caused by the last systemic elimination of articaine (ie, its wide toxic therapeutic ratio).

Nonspecific esterase activity in 'hairy cells'.

Nonspecific esterase activity using alpha-naphthyl butyrate as substrate was found to be present in hairy cells from patients with hairy cell leukemia. Activity of this enzyme was markedly diminished and in some instances obliterated by sodium fluoride. Since alpha-naphthyl butyrate is believed to be a more specific substrate for monocytic-type nonspecific esterase than alpha-naphthyl acetate, its presence in hairy cells combined with fluoride inhibition which is also characteristic of monocytic nonspecific esterase provides additional evidence of monocytic properties of hairy cells.

1-naphthyl acetate esterases in fluids and tissues of jaw cysts.

The activity and electrophoretic mobility of 1-naphthyl acetate esterases in cystic fluids and cystic tissues of ameloblastomas, follicular and apical cysts were examined. The cystic fluids showed lower activities than sera but had very similar patterns on the electrophoretogram. The activity levels of the three kinds of cystic fluids were not statistically significantly different. The fluid esterases may have originated from serum but they were not produced by the cystic lining tissue. Ameloblastoma tissues showed the highest activity per wet weight and per mg protein of the three kinds of cyst lesions (P less than 0.05). On the electrophoretogram, the esterase-I activity constituted 41% of the total activity in ameloblastomas, whereas in follicular cysts and apical cysts the esterase-I activity constituted 32% and 24% of the total activity, respectively.

[Relationship between the activity of the kallikrein, plasmin and thrombin systems of the blood during intense physical exertion]. / Sootnoshenie aktivnosti kallikreinovoi, plazminovoi i trombinovoi sistem krovi pri intensivnoi fizicheskoi nagruzke.

The authors studied the changes in the level of precursors of kallikrein, plasmine, and their inhibitors with the aid of a complex method. Blood plasma of sportsmen was examined--of healthy persons and of those with the syndrome of myocardial overstraining under conditions of rest and intensive bicycle ergometric exercises. The results obtained and correlation analysis data pointed to the functional association of the "Hageman's factor system". Sportsmen with the overstrain syndrome displayed an aggravation of the functional possibilities of humoral systems of the hemovascular regulation, this being expressed in a reduced level of the proenzymatic activity and a reduction of the inhibitor values. Correlation of the mentioned indices was disturbed both at rest and during the exercises.