Differential energy requirements for platelet responses. A simultaneous study of aggregation, three secretory processes, arachidonate liberation, phosphatidylinositol breakdown and phosphatidate production

Previous studies have indicated different energy requirements for some platelet responses; these differences could, however, be due to inadequate methodology and differences in platelet preparation. The present study describes the effect of decreasing ATP availability on seven platelet responses measured in gel-filtered human platelets. The cells, prelabelled with 5-hydroxy[(3)H]tryptamine, [(3)H]- or [(14)C]adenine, [(32)P]P(i) or [(3)H]arachidonate, were incubated with antimycin A and 2-deoxy-d-glucose. Platelet responses induced by thrombin and collagen (secretion only), level of metabolic ATP and the adenylate energy charge (AEC) were determined at various times during incubation. Platelet aggregation was rapidly inhibited after a lag of 5-15 min and with 50% inhibition at AEC = 0.55-0.60. Secretion of 5-hydroxy[(14)C]tryptamine and ATP + ADP from dense granules and of fibrinogen and beta-thromboglobin from alpha-granules were inhibited in parallel, without a lag and with 50% inhibition at AEC = 0.65-0.70. The inhibition of secretion of platelet factor 4 from the alpha-granules followed another pattern with 50% inhibition at AEC = 0.70-0.80. Breakdown of [(3)H]-phosphatidylinositol, formation of [(3)H]- and [(32)P]-phosphatidate, liberation of [(3)H]arachidonate and secretion of acid hydrolases were inhibited in parallel and inhibition was present at the start of incubation with 50% inhibition at AEC = 0.80-0.87. These results suggest that the responses have different energy requirements, increasing in the order: aggregation < dense granule and alpha-granule secretion < acid hydrolase secretion, phosphatidylinositol breakdown, phosphatidate formation and arachidonate liberation. The powerful inhibition of phosphatidylinositol breakdown by metabolic inhibitors suggests that energy-requiring steps are involved in the activation of phospholipase C.

Monocyte function in cirrhosis

Monocyte function has been studied in a total of 51 patients with biopsy-proven cirrhosis and 35 controls. There was significantly reduced monocyte spreading (p less than 0.05), chemotaxis (p less than 0.02), bacterial phagocytosis (p less than 0.05) and bacterial killing (p less than 0.02) in the cirrhotics compared to the controls. Monocytes from patients with cirrhosis produced significantly less of the lysosomal enzymes N-acetyl beta-glucosaminidase and beta-glucuronidase than those obtained from the controls (p less than 0.02). There was no significant difference in the number of monocytes obtained, the number of macrophage precursors, and the nitro-blue tetrazoline (NBT) reduction between the cirrhotic and the controls. The reduced function appeared to be mainly due to a circulating inhibitory factor and could be corrected by incubation of the cirrhotic cells in serum from control subjects. The response of monocytes from patients with cirrhosis did not differ from the controls in their response to added endotoxin or latex particles suggesting that they are capable of a normal response in the absence of the inhibitory factor. Paired specimens of portal and systemic serum were collected from patients with no evidence of liver disease undergoing vascular surgery. When added to normal human monocytes the portal serum caused a significant reduction in bacterial killing (p less than 0.02) and chemotaxis (p less than 0.05) compared to results obtained in the paired systemic serum. Mixing experiments suggests the presence of an active inhibitor in the portal serum. The results suggest that monocyte function is reduced in cirrhosis apparently due to a serum inhibitor which may have originated from the portal vein. The abnormalities may account in part for the increased susceptibility of these patients to infection.

[Effects of cis-platin on the contractile system of polymorphonuclear leukocytes]

The effects of cis-Platinum, a new antitumor drug, on guinea pig polymorphonuclear functions related to subplasmalemmal fibrillar structures, were investigated. The compound markedly decreased chemotaxis. Zymosan particles engulfment and degranulation. The depression of these leucocyte activities adds to the already known drug induced myelotoxicity .

Modulation of beta-adrenergic receptor by hydrocortisone in human polymorphonuclear leukocytes

We have examined the influence of isoproterenol and hydrocortisone on the cycle AMP content and lysosomal enzyme release from highly purified human polymorphonuclear leukocytes. It was found that isoproterenol, although a potent stimulus for cAMP accumulation in human lymphocytes, had only marginal effects on both cAMP content of PMN and enzyme release. Since corticosteroids have been reported to increase the response to beta-agonists in various tissues, it was considered that some of the anti-inflammatory potential of corticosteroids might be related to enhancing the response of PMN to beta-agonists. The influence of hydrocortisone on the response to isoproterenol was accordingly examined. It was found that hydrocortisone did in fact augment the isoproterenol-induced increase in cAMP content. In contrast to the potentiation of cAMP accumulation caused by hydrocortisone and isoproterenol together, the two agents produced only an additional inhibition of enzyme release. Since the inhibition of lysosomal enzyme release from human PMN did not closely reflect the changes observed in the cAMP content, a possible compartmentalization of intracellular cAMP is suggested.

The discharge of primary and secondary granules during immune phagocytosis by normal and chronic granulocytic leukaemia polymorphonuclear neutrophils

The two types of granule in polymorphonuclear neutrophils may have distinct functions. The primary granule enzymes are responsible for killing and digesting ingested micro-organisms while the secondary granule constituents may have regulatory functions outside the cell. This hypothesis is supported by finding that during immune phagocytosis of a yeast, nearly all of the neutrophil's secondary granule vitamin B12-binding protein is lost from the cell and 80% can be accounted for in the medium. Much less of the primary granule enzymes, beta-glucuronidase and acid phosphatase, are lost from the cells and very little can be detected in the medium. Lysozyme is a constituent of both types of granule and its behaviour is intermediate. There is no difference in the release of these granule constituents from chronic granulocytic leukaemia neutrophils compared with normal neutrophils.

Release of lysosomal enzymes after partial hepatectomy: study of patients with and without cirrhosis of the liver

Serum activities of lysosomal enzymes beta-glucuronidase and acid phosphatase were serially estimated in 14 patients with and without cirrhosis of the liver who underwent 40% to 80% hepatic resection. Substantial increases in enzyme activities were observed two to eight weeks after operation in ten of 11 patients who did not suffer from postoperative liver failure. Regeneration of the residual livers was almost satisfactory in all 11, as evidenced by clinical, roentgenologic, and histologic findings. In three patients with advanced cirrhosis who died of hepatic failure 21 to 39 days after extensive hepatic resection, there was neither the enzymatic reaction nor evidence of regeneration of the liver remnants. In the light of this study and our previous experimental studies, serial determination of the lysosomal enzyme activities in blood is probably a beneficial biochemical index for detection of progressive hepatic regeneration.

Characterization of rat polymorphonuclear leukocyte subcellular granules

The bactericidal subcellular granules of rat peritoneal neutrophils were studied to determine selected physical and biochemical characteristics. Isopycnic centrifugation of these granules resolved them into three subpopulations: specific granules (buoyant density = 1.176) as well as light and heavy azurophil granules (buoyant density = 1.20 and 1.22, respectively). These buoyant densities corresponded closely to those of similarly isolated human granules. Specific granules of rat peritoneal neutrophil contained 68 per cent of the sedimentable alkaline phosphatase activity and part of the lysozyme of the whole rat peritoneal neutrophil. The light azurophil granules contained the remainder of the lysozyme, as well as a substantial portion of the beta-glucuronidase activity. Peroxidase was detected in both light and heavy azurophil granules, as was neutral protease. Morphologically, the rat specific granules were round or slightly ovoid organelles (0.10 to 0.13 micrometer in diameter). The azurophil granules were larger (0.3 micrometer) ellipsoid as well as round in shape, and stained strongly for peroxidase. These granules were significantly smaller than the crystal-containing granules of eosinophils.

Serum activities of lysosomal enzymes in patients with liver cell carcinoma

Serum activities of two lysosomal enzymes, beta-glucuronidase and acid phosphatase, were estimated in 66 patients with liver cell carcinoma, 10 with secondary liver cancer, 14 with cirrhosis of the liver, and 9 normal controls. A substantial increase in the enzyme activities was found in patients with liver cell carcinoma but not in those with secondary liver cancer. The degree of the enzyme elevations paralleled the stage of hepatoma. Although the serum activities of both enzymes were also elevated in patients with liver cirrhosis, the elevations were significantly higher in hepatoma than in liver cirrhosis. Possible mechanisms for the elevation of serum lysosomal enzyme activities in hepatoma are discussed, but further studies are necessary to elucidate the biological and clinicopathological significance of estimating serum lysosomal acid hydrolases in patients with primary liver cell carcinoma.

The effect of various stimuli and calcium antagonists on the fluorescence response of chlorotetracycline-loaded human neutrophils

Chlorotetracycline has been used in neutrophils and other cells as probe of the state of membrane-bound calcium. We report here that human neutrophils treated with chlorotetracycline response to soluble secretagogues by a prompt decrease in chlorotetracycline fluorescence. This response was observed within 2-5 s, making it one of the most immediate reactions in neutrophils to stimulation, and was obtained with three secretagogues studied: a chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine, a tumor promotor (phorbol myristate acetate) and a lectin (concanavalin A). The responses of neutrophils to the three stimuli differed both quantitatively and qualitatively. The calcium EGTA, did not effect the onset of the decrease in chlorotetracycline fluorescence, suggesting that the probe was measuring changes in intracellular calcium pools. The intracellular calcium antagonists, TMb-8, W-7 and trifluoperazine, did not block, but actually augmented, the fluorescence response. All four of these calcium antagonists blocked the recovery of chlorotetracycline fluorescence which was usually observed several minutes after stimulation with N-formyl-methionyl-leucyl-phenylalanine. This suggests that recovery was dependent upon both extracellular calcium and active calmodulin. The results are consistent with the hypothesis that changes in chlorotetracycline fluorescence reflect changes in a pool of membrane-bound 'trigger calcium', the release of which is an essential first step in stimulus-response coupling in human neutrophils.

The effects of retinoids on neutrophil functions in vitro

Vitamin A (retinol) and its analogues (retinoids) are clinically effective in cystic acne and psoriasis, diseases in which neutrophils may constitute major components of inflammatory cell infiltrates. We found that the earliest histopathologic alteration in psoriasis is the disappearance of neutrophils at 2 to 4 weeks after the initiation of therapy with etretinate. Since retinoids may exert anti-inflammatory effects by virtue of an action upon neutrophils, we studied the effects of the following retinoids on discrete neutrophil functions in vitro: retinol, retinyl acetate, retinal, tretinoin, isotretinoin, etretinate, and Ro 10-1670. Although they had no significant effects upon aggregation, chemokinesis, or chemotaxis, all of the retinoids, with the exception of etretinate and Ro 10-1670, profoundly inhibited superoxide anion production and lysosomal enzyme release. Tretinoin and isotretinoin were the most effective inhibitors. We propose that these drugs exert their pharmacologic effects (resolution of inflammatory lesions) by inhibiting the release of mediators of inflammation and by preventing the accumulation of neutrophils in acne lesions when applied topically or systemically, respectively.

Cytochemical markers for T mu and T gamma. A comparative study

A procedure is described for the cytochemical detection of esterase alpha naphtyl acetate (ANAE) and beta glucuronidase (BG) activity in the circulating lymphocytes of man. The number of BG positive cells (TBG) as evaluated on the smears of Ficoll Urovision purified cells, correlated well with the number of T gamma (EA gamma rosette forming cells with ox red blood cells) in the same blood samples of a group of healthy persons and patients, with pollinosis, atrophic rhinitis and bacterial asthma. In healthy persons, the number of T gamma cells by rosette method was 12.5 +/- 0.5% whilst BG positive cells were 14.0 +/- 14%. The patients had an equal number of BG positive cells and T gamma too. The present study broadly confirms ANAE activity as a cytochemical marker for T mu cells. These results tested that T lymphocytes can be accurately enumerated by cytochemical evaluation of ANAE activity in human lymphocytes and suggested the usefulness of BG activity in the enumeration of T lymphocytes in man.

Effect of glutathion pretreatment on hypothermic ischemic cardioplegia

Glutathion (GSH) plays an important role in maintenance of the redox state of the myocardium and acts as the membrane stabilizer. Seventeen patients who underwent cardiac surgery were subjected to cardiopulmonary bypass (CPB) and ischemic cardioplegia. The effect of GSH on ischemic myocardium was evaluated by serum lysosomal enzymes (acid phosphatase, beta-glucuronidase), isoenzymes of creatine phosphokinase (MB-CPK) and aspartate aminotransferase (m-GOT). standard CPB was instituted and systemic hypothermia was employed. GSH was administered to 8 patients in a dose of 200 mg/kg i.v. prior to institution of CPB. Mixed venous blood was sampled before administration of GSH, 10 min after institution of CPB and 0, 1, 6, 24 and 48 hr of reperfusion period following cardioplegia. Activity of acid phosphatase and beta-glucuronidase were significantly suppressed in the GSH-treated group compared to the non-treated group at 24 hours of reperfusion and immediately after aortic unclamping, respectively. Serum MB-CPK levels remained stable during reperfusion, but in the non-treated group, the level increased significantly at 6 hours of reperfusion. Increment of serum m-GOT levels was significantly suppressed at 1, 6 and 24 hours of reperfusion, compared to the non-treated group. These data suggest that pretreatment of GSH can protect the myocardium subjected to CPB from ischemic insult.

Effect of indomethacin and naproxen on the metabolism of glycosaminoglycans

Indomethacin and naproxen were examined regarding their effects on glycosaminoglycan metabolism in normal albino rats. The biosynthesis of sulphated glycosaminoglycans as evaluated by the uptake of [35S-]sulphate and the content of glycosaminoglycans were measured in specimens of skin, liver and kidney. The results indicated that the biosynthesis of sulphated glycosaminoglycans was significantly inhibited by both these drugs, thus reflecting their anti-inflammatory properties. The catabolism of glycosaminoglycans was followed by estimating the activities of lysosomal glycohydrolases, viz., beta-glucuronidase, beta-N-acetyl glucosaminidase and cathepsin D in liver, kidney and spleen and urinary excretion of hexosamine and uronic acid. The results, considered collectively, indicated that both indomethacin and naproxen depressed the metabolism of glycosaminoglycans.

Binding of lipoprotein lipase to endothelial cells in culture

Equilibrium-binding data of highly purified avian lipoprotein lipase to cultured bovine endothelial cells demonstrate the presence of a class of high affinity sites. Analysis of the binding function by weighted least squares technique yielded an association constant of K = 0.7 X 10(7) M-1 and a maximum binding capacity of 1.6 micrograms/1.9 X 10(6) cells. Lipoprotein lipase was monitored both by its catalytic activity and a sensitive radioimmunoassay which permitted the accurate measurement of nanogram quantities of enzyme protein. Specific activity of the bound enzyme was similar to that of the initial purified enzyme. Lipoprotein lipase binding to endothelial cells was inhibited 80% by preincubating cells in 0.1% trypsin for 3 min at 37 degrees C, 92% by 0.01% pronase, and 91% by 0.008% proteinase K. Heparin was most efficient in releasing lipoprotein lipase from endothelial cells. Fifty per cent of the enzyme appeared in the medium at a concentration of 3 micrograms/ml of heparin. At the same concentration of heparan sulfate, 20% of the enzyme was released. Hyaluronic acid and chondroitin sulfate were not effective in stimulating enzyme release. Preincubating endothelial cells with purified human platelet endoglucuronidase for 1 h at 37 degrees C led to a 90% reduction in lipoprotein lipase binding. Endoglucuronidase was purified 20,000-fold as compared to the initial platelet lysate by a 5-step purification method. The extent of inhibition of binding was shown to be dependent on concentration of endoglucuronidase in the preincubation medium. The specificity of platelet endoglucuronidase and the demonstration that the preparation utilized contained no detectable protease activity is further evidence that lipoprotein lipase is bound to endothelial cell heparan sulfate or heparan sulfate-like molecules.