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L Kesner

Publications and source records attributed to L Kesner.

At least 19 recordsLinked to original sources
PubMed1990

Inactivation of alpha 1-proteinase inhibitor by Cu(II) and hydrogen peroxide.

When alpha 1-proteinase inhibitor was treated with 1-5 microM CuSO4 in the presence of H2O2 (250-1000 microM), its elastase inhibitory capacity was markedly decreased. Several other metal ions tested had either very little or no effect. The Cu(II)-catalyzed decreased in the inhibition of elastase activity can also be demonstrated in dialyzed plasma. These results are consistent with the hypothesis that in several pathological conditions in which extracellular copper levels are elevated, Cu(II)-catalyzed peroxidation of alpha 1-proteinase inhibitor may occur at sites of inflammation where H2O2 is secreted as a major product by activated phagocytes.

Blood↗
PubMed1990

Cyst fluid proteases.

The precise origin of breast cyst fluid remains obscure. Molina has presented evidence that type II cysts (high Na/K ratio) may be transudative, that is, partly derived from plasma elements which enter through gap junctions, while Type I cysts (high K/Na ratio) are primarily secretory. In transudative cysts, plasma protease inhibitors may be present, but the balance between protease and its inhibitors may fluctuate as a result of as yet undetermined circumstances. An imbalance between the protease activity of cyst fluid and its inhibitors may be involved in the pathogenesis of breast gross cystic disease. Accumulation of protein fragments with resistant bonds would produce an elevated oncotic pressure causing a shift of fluid into the cyst capsule. Albumin is a good substrate for the protease, which may account for its low concentration in cyst fluid. The major protease fraction closely corresponds to the progesterone binding protein (GCDFP-24) described by Haagensen. Affinity columns containing aprotinin or benzamidine ligands retain the protease which can then be eluted with 0.5 M NaCl. The HD1 protease and progesterone binding protein are either tightly complexed or are the same protein. Cyst fluid is a complex mixture of biomolecules. If the progesterone binding protein is a protease, many questions must be answered concerning the influence of cyst fluid steroids, lipids, anions, and cations on enzyme action. Determination of the amino acid sequence of HD1 may help elucidate the source of the enzyme and its relationship to other tissue proteases. Human plasma contains inhibitors of this protease activity. When pooled, dialyzed plasma was mixed with pooled, dialyzed cyst fluid, the ratio of plasma/cyst fluid at which all activity was inhibited was 6/1. A comparison of the rate of cleavage of three 14C-protein substrates shows that cyst fluid proteases cleave in a characteristic manner, distinct from either trypsin or calpain. A simple method for semiquantitative estimation of protease activity in cyst fluid is described which utilizes prestained Coomassie blue-albumin containing agarose gel plates. All cyst fluids tested had protease activity but showed variability in their ability to cleave 14C-albumin by a factor of 4. There is much direct and indirect evidence that proteases are involved in the cancer process. In view of the higher than normal incidence of breast cancer in women who have had gross cystic breast disease, the possibility exists that an imbalance between these proteases and their inhibitors is somehow involved.

Exudates and Transudates↗
PubMed1988

Proteases in cyst fluid from human gross cyst breast disease.

Cyst fluid from women with gross cystic breast disease was found to contain protease activity when assayed against [14C]albumin. At least six different proteases were detected when the fluid was fractionated by a combination of S-300 Sephacel, hydroxylapatite, and DEAE-Sephacel chromatographic techniques. The distribution of the proteases appeared to be related to the ionic composition of the fluids. A major protease component, found in both high Na and high K fluids, was isolated. It showed chymotryptic cleavage characteristics against the beta-chain of insulin. It was partially inhibited by alpha 2-macroglobulin, N-tosyl-L-phenylalanine chloromethyl ketone, and benzamidine but not by leupeptin, pepstatin, N-tosyl-L-lysine chloromethyl ketone, or alpha 1-protease inhibitor. The protease has an apparent molecular weight of 110,000 with Mr 24,000 subunits. This protease may be identical or closely associated with Haagensen's GCDFP-24 progesterone binding protein which was isolated in a similar manner. An imbalance between protease and protease inhibitors in cyst fluid may account for gross cyst formation and may be involved in the tumorigenic process. The accumulation of poorly diffusible peptide fragments, as a result of protease activity, would increase the oncotic pressure leading to enlargement of the cyst cavity as water enters to reestablish osmotic equilibrium.

Female↗
PubMed1987

Generation of hemolytic activity in ozone-treated phosphatidylcholine.

When liposomes prepared from purified soybean phosphatidylcholine were treated with ozone, at least two types of hemolytic agents were formed. One type was stable at 0 degree C but was destroyed rapidly at 37 degrees C. A second type was evolved during storage of ozone-treated phosphatidylcholine at 37 degrees C in the absence of EDTA. This study is concerned mainly with the heat-labile type. The hemolytic activity was not associated with lipid hydroperoxides. A number of substances were shown to inhibit the hemolytic activity and these may be divided into two classes. The first included cysteine, polyamines, n-heptylamine, semicarbazide, and tryptophan. Preincubation of the ozone-treated phosphatidylcholine was necessary with a Class 1 inhibitor, presumably for the interaction of the inhibitor with a functional group of the hemolytic agents. The Class II inhibitors, including BHT and vitamin C, required no preincubation. These possibly abolished the hemolytic activity by scavenging free radicals in the process.

Animals↗
PubMed1984

Degradation of articular cartilage by copper and hydrogen peroxide.

When porcine articular cartilage particles were incubated in the presence of Cu2+ and H2O2 at pH 7.4, solubilization of collagen and proteoglycan was observed. Both agents were necessary and the rate of solubilization was concentration dependent. Other transition metal ions showed much lower catalytic activity. The solubilized polypeptides were polydispersed in size and the hydroxyproline content of the larger fragments was 13% by weight. Further incubation of the released material with Cu2+ and H2O2 resulted in further degradation and partial destruction of hydroxyproline residues. Competitive studies with scavengers of OH X and 1O2 as well as the effect of D2O excluded these two species as major mediators in this system.

Animals↗
PubMed1982

Copper(II)-catalyzed lipid peroxidation in liposomes and erythrocyte membranes.

Cu++ was uniquely capable of catalyzing the peroxidation of rat erythrocyte membrane lipid in the presence of 10 mM H2O2, whereas several other transition metal ions were without significant effect. In contrast, peroxidation of soybean phospholipid liposomes could be catalyzed with decreasing efficiency by Co++, Cu++, Pb++, or Cr+++ also in the presence of H2O2. The effect of imidazole on Cu++- catalyzed lipid peroxidation was stimulatory in liposomes and inhibitory in membrane preparations, whereas EDTA, histidine, citrate and alanine inhibited peroxidation in both systems. EDTA could stop the peroxidation after initiation, but catalase could not, indicating that Cu++ alone was necessary for the propagation of the chain reaction. Competitive inhibition studies with various scavengers of hydroxyl radicals or singlet oxygen and the absence of significant reaction enhancement by D2O indicated that neither of these reactive oxygen species was a major mediator in the Cu++-H2O2 oxidative system. A copper-oxygen complex may be directly involved in the initiation of peroxidation. Normal erythrocyte membranes and phospholipid liposomes also differ in their sensitivities toward external oxidative stress. In the absence of H2O2, CU++ (0.2 mM) was capable of catalyzing lipid peroxidation in liposomes, aged erythrocyte membranes and membranes from vitamin-E-deficient rats; however, freshly prepared membranes from control rats and liposomes containing alpha-tocopherol required H2O2 greater than 2 mM for the catalytic effect of Cu++ to be observed.

Animals↗
PubMed1979

Inhibition of erythrocyte membrane (Na+ + K+)-activated ATPase by ozone-treated phospholipids.

Ozone-treated aqueous suspensions of natural phospholipids yield at least two types of inhibitors of human erythrocyte membrane (Na+ + K+)-ATPase. The more labile ones appear to be carbonyl-containing substances whose inhibitory properties are enhanced if ozonolysis takes place in the presence of putrescine or glycine. Other amines of similar structure are much less effective as potentiators. Semicarbazide destroys the inhibitory properties of the more labile substances and can release putrescine from the complexes it forms with the carbonyl products of ozonolysis. 3the more stable inhibitors are unaffected by putrescine, glycine, or semicarbazide. Synthetic, saturated phospholipids do not produce these inhibitors during ozonolysis.

Erythrocyte Membrane↗
PubMed1977

[Angiographic study of the vascularization of primary malignant tumors of the liver: histological correlation].

During the last seven years 118 patients with histologic diagnosis of malign tumor in the liver were examinated by selective angiography, amongst other diagnostic recourses: 14 patients had primitive tumors: 12 hepatoma, 1 cholangiocarcinoma and 1 hepatocholangiocarcinoma. In 12 patients resection was contraindicated preoperative by the angiographic demonstration of the extension of the tumor to both lobes. In 1 patient with cholangiocarcinoma, the tumor was resected with an outlive of 4 years. In 1 patient with hepatoma very vascular a hard league of the right hepatic artery was done. Two months later angiography demonstrated a rich revascularisation of the tumor with development of the colateral circulation. In our experience the hiper or hipovascularization is related with the degree of fibrosis which accompanies the tumor and no so much with the histologic type, the degrees of differentiation or the existence of intratumoral necrosis. Emphasis is been done to show the diagnostical difficulties of hipovascularized tumors and the importance of angiography in the preoperative evaluation of hepatic tumors.

Adult↗
PubMed1975

Continuous single pass perfusion of the isolated kidney.

The use of continuous single pass perfusion to study the metabolism of isolated kidneys reveals that active metabolic processes continue in the hypothermically preserved kidney. These preliminary experiments described demonstrated a rapid uptake of substrates from the perfusion media in the first 24 hrs of storage, followed by a release of organic acids in the subsequent 24 to 72 hrs. Urea was found to be easily eliminated from the kidney. This technique may be useful for studying events related to loss of renal function by pinpointing specific residual biochemical activity and lesions that occur during prolonged preservations. An eventual correction or prevention of such lesions might be feasible in order to improve preservation techniques.

Animals↗
PubMed1975

Possible interactions between the urea cycle and synthesis of pyrimidines and polyamines in regenerating liver.

Ornithine levels rise progressively in the liver of partially hepatectomized rats, probably as a consequence of the increased flow of metabolites through the urea cycle. Ammonia and urea concentrations in the blood and liber of partially hepatectomized animals are not significantly different from those of sham-operated rats. However, in regenerating livers, the ability to remove ammonia from the blood is close to its maximal limit. Ammonia overload leads to the production of large amounts of orotic acid and causes a marked elevation of hepatic ornithine decarboxylase activity. Among the pyrimidine precursors dihydroorotic acid injections increase the activity of the enzyme while orotic acid is without effect. A peak of labeled material that corresponds to dihydroorotic acid was identified by partition chromatography of acid-soluble extracts of livers of partially hepatectomized rats previously given injections of [14-C2 bicarbonate. The labeling of dihydroorotic acid from [14-C] bicarbibate is increased in the liver of rats given injections of ornithine. Despite the difficulties involved in studies of ornithine decarbozylase activity in vivo, our results suggest that mutual interactions between urea, pyrimidine, and polyamine synthesis take place during liver regeneration.

Adrenalectomy↗
PubMed1975

Determination of orotic and dihydroorotic acids in biological fluids and tissues.

In commonly used procedures for colorimetric assay of orotic acid in biological materials, certain substances interfere, positively or negatively. Some that interfere negatively are ornithine, cysteine, citrulline, tyrosine, proline, hydroxyproline, and polyamines. Protein and interfering agents are easily removed by first isolating the total organic acid fraction. The orotic acid in this fraction can then be determined by an established colorimetric procedure. A rapid liquid-liquid column-chromatographic procedure is described, if analysis of both dihydroorotic and orotic acid is required.

Animals↗