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Biomedical subjects

M Waite

Publications and source records attributed to M Waite.

At least 73 records · Page 4Linked to original sources
PubMed1983

Mechanism of arachidonic acid release in human polymorphonuclear leukocytes.

Previous studies have demonstrated that [3H]arachidonic acid is released from prelabeled human neutrophil phospholipids when the cells are stimulated by calcium ionophore A23187 or by opsonized zymosan. Neither lysophospholipid generated by phospholipase A2 activity, diacylglycerol nor monoacylglycerol produced via phospholipase C/diacylglycerol lipase action have been identified following neutrophil challenge. The inability to detect any intermediates during the release of arachidonate is due to either rapid reacylation of lysophospholipid or conversion of diacylglycerol (monoacylglycerol) to cellular acylglycerols. The addition of exogenous [14C]fatty acid at the time of challenge was employed to determine the involvement of either phospholipase A2 or phospholipase C activities. Neutrophil stimulation with calcium ionophore A23187 resulted in an incorporation of exogenous [14C]arachidonate into phosphatidylinositol and phosphatidylcholine, those phospholipids which specifically release arachidonate. When the saturated fatty acid, [14C]stearate, replaced [14C]arachidonate, very little [14C]fatty acid was incorporated into any of the phospholipid species. Lipid phosphorus measurements revealed no significant mass change in any phospholipid class following ionophore challenge. Production of [14C]phosphatidic acid was not detected, as would be expected if diacylglycerol kinase and de novo phospholipid metabolism were significantly involved.

Arachidonic Acid↗
PubMed1983

Arachidonic acid metabolism in polymorphonuclear leukocytes from patients with chronic granulomatous disease.

The effect of the calcium ionophore A23187 on the release and metabolism of [3H]arachidonic acid was examined in normal polymorphonuclear leukocytes and those obtained from patients with chronic granulomatous disease. The ionophore A23187 which stimulates oxidative metabolism in normal polymorphonuclear leukocytes was ineffective in increasing oxidative metabolism (chemiluminescence) in polymorphonuclear leukocytes from patients with chronic granulomatous disease. However, the ionophore A23187 stimulated the release of [3H]arachidonic acid from chronic granulomatous disease neutrophil phospholipids and stimulated its metabolism into hydroxyeicosatetraenoic acids and leukotrienes.

Arachidonic Acid↗
PubMed1983

12-O-tetradecanoyl-phorbol-13-acetate enhancement of the tumorigenic potential of herpes simplex virus type 2 transformed cells.

The consequences of tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) interaction with clonal HSV-2-transformed nontumorigenic and weakly tumorigenic cells were studied. Enhancement of anchorage-independent growth (cloning efficiency) occurred in a dose-dependent manner when transformed but not nontransformed cells were pretreated with TPA. All subclonal nontumorigenic cell lines progressed to become tumorigenic after 20 serial passages in the presence of TPA. Also, subclonal, weakly tumorigenic cell lines were enhanced in tumorigenic potential (measured by reduced latent period for tumor formation) after transient treatment with TPA. In summary, TPA irreversibly enhanced the cloning efficiency and tumorigenic potential of transformed cells long after initiation by the virus.

Animals↗
PubMed1983

The use of acetylated cytochrome c in detecting superoxide anion production in rabbit alveolar macrophages.

Polymorphonuclear phagocytes have been shown to undergo marked alteration in oxidative metabolism during phagocytosis. These alterations, collectively known as the "respiratory burst", include increased glucose oxidation through the hexose monophosphate shunt (1), increased oxygen consumption (1), and increased superoxide (O-2)3 (2) and H2O2 production (3). Similar metabolic events have also been shown to occur in the rabbit alveolar macrophage (AM). There is consistent evidence that the macrophage undergoes increased oxygen consumption (4-6) and hexose monophosphate shunt activity (4-9) upon phagocytosis. There are conflicting data, however, concerning the ability of the macrophage to produce O-2. Some studies suggest that macrophages are incapable of producing measurable amounts of O-2 upon phagocytosis (7, 10-12). Other studies, however, suggest that macrophages are indeed capable of producing substantial amounts of O-2 during phagocytosis (8, 13-15). This study was designed to resolve the discrepancies in the literature concerning O-2 production in macrophages.

Acetylation↗
PubMed1982

Stimulation of deacylation in Madin-Darby canine kidney cells. Specificity of deacylation and prostaglandin production in 12-O-tetradecanoylphorbol-13-acetate-treated cells.

Madin-Darby canine kidney cells deacylate arachidonic acid from cellular phospholipid in response to 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and convert the free arachidonic acid to prostaglandins. We have used this system to characterize the acyl specificity of deacylation. Cells were labeled with either [14C]linoleic, [14C]eicosatrienoic (delta 8,11,14 or delta 5,8,11), or [14C]arachidonic acid and stimulated with 10 nM TPA. We found that TPA stimulated the deacylation of all four acids, primarily from phosphatidylethanolamine and phosphatidylcholine.l Only products from linoleic (presumably through chain elongation and desaturation), eicosatrienoic (delta 8,11,14), and arachidonic acids produced prostaglandins. Those produced from linoleic and eicosatrienoic acid (delta 8,11,14)-labeled cells were determined to be primarily of the 1-series, while arachidonic acid-labeled cells produced prostaglandins of the 2-series. Together these results indicate that the stimulated deacylation of phospholipids is not specific for arachidonic acid and that the membrane acyl composition controls the particular series of prostaglandin which is produced.

Animals↗
PubMed1982

Uptake and metabolism of free fatty acids by the Morris 7777 hepatoma and host rat liver.

The relative capacity of Morris 7777 hepatomas and livers of tumor-bearing rats to take up and subsequently metabolize intravenously injected radiolabeled free fatty acids was investigated. The objective was to determine differences in lipid metabolism which may affect the lipid composition previously observed in this tumor. Both tissues demonstrated comparable selectivity in the uptake of palmitate, linoleate and arachidonate from blood, although the hepatoma took up one-tenth as much free fatty acid per g wet wt as liver. A much greater percentage of fatty acid taken up by the hepatoma was converted to aqueous soluble radioactivity, perhaps the result of oxidation. In the hepatoma, palmitate was incorporated into phospholipid molecular species in a pattern similar to that observed for diglyceride, which suggested that phospholipid synthesis occurred predominantly de novo. On the other hand, in liver, a large percentage of palmitate was incorporated into polyunsaturated phospholipid molecular species that were not present in the diglyceride pool, which suggested significant incorporation by the acylation of monoacyl phosphoglycerides. These studies indicate that the specificity for the uptake of fatty acids was not different in the two tissues; however, the subsequent metabolic processes are markedly different.

Animals↗
PubMed1981

Source of arachidonic acid for prostaglandin synthesis in Madin-Darby canine kidney cells.

Madin-Darby canine kidney cells deacylate arachidonic acid from cellular phospholipids in response to stimulation with 12-O-tetradecanoyl-phorbol-13-acetate and convert the free arachidonic acid to prostaglandins. We have used this system to determine which phospholipids serve as donors of the free arachidonic acid. The cells were labeled with [3H]arachidonic acid and [14C]palmitic acid which were preferentially incorporated into phosphatidylethanolamine and phosphatidylcholine, respectively. 12-O-Tetradecanoyl-phorbol-13-acetate stimulation caused a marked deacylation of arachidonic acid from phospholipids including 1-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine; phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and phosphatidylcholine were also donors of arachidonate. A smaller percentage of the [14C]palmitic acid was lost from phospholipids after stimulation and indicates that the stimulated deacylation of phospholipids is preferential for [3H]arachidonic acid compared to [14C]palmitic acid. Analysis of the cellular phospholipid acyl composition demonstrated that 12-O-tetradecanoyl-phorbol-13-acetate stimulation caused a marked decrease in the content of arachidonic acid and an increase in saturated and monounsaturated fatty acids. These findings suggest that the phospholipids which serve as arachidonic acid donors are rapidly reacylated with more saturated fatty acids.

Animals↗
PubMed1981

Specificity of lipoprotein lipase and hepatic lipase toward monoacylglycerols varying in the acyl composition.

We report here that both the hepatic lipase and lipoprotein lipase demonstrate specificity towards the acyl group present on monoacylglycerols. We found that unsaturated glycerides are more readily degraded than saturated glycerides. However, the basis for this specificity appears to be different for each enzyme. The activity of the hepatic lipase, but not the lipoprotein lipase, could be stimulated by Triton X-100 and phosphoglycerides. We interpret these results to show that while both the lipoprotein lipase and hepatic lipase are sensitive to the physical state of the substrate (as shown by fluorescence depolarization), the lipoprotein lipase also has a low affinity for monoacylglycerols that contain a saturated acyl group. In the course of this study we also obtained evidence that some type of phase separation occurs when mixtures of saturated and unsaturated monoacylglycerols are prepared.

Animals↗
PubMed1981

Neutrophil responses to platelet-activating factor.

1-O-Alkyl-2-O-acetyl-sn-glycerol-3-phosphorylcholine (i.e., platelet-activating factor) was prepared and confirmed to possess potent platelet aggregating activity. It was also potent in aggregating and degranulating rabbit and human neutrophils. When injected into rabbits, the lipid induced profound neutropenia, thrombocytopenia, and anaphylactic symptoms. The lyso derivative of this lipid, 1-O-alkyl-sn-glycerol-3-phosphorylcholine, was inactive or several orders of magnitude weaker in inducing these responses. The acetylated lipid appears to be a potent stimulator of both platelets and neutrophils. Its anaphylactic-like toxicity may be related, at least in part, to its ability to aggregate or otherwise stimulate these cells.

Animals↗
PubMed1981

Phospholipid synthesis in human embryo fibroblasts infected with herpes simplex virus type 2.

The effect of herpes simplex virus type 2 infection on the synthesis of phospholipids in human embryo fibroblasts was determined at temperatures permissive (35 C) or nonpermissive (42 C) for virus replication. Incorporation of [32P]i was decreased by herpes simplex virus type 2 infection after 6 hr, which corresponds to the time of initiation of progeny virus production. No differences were observed in the relative incorporation of [32P]i phospholipid classes. In another series of experiments cells were labeled with [3H]ethanolamine before infection and with [14C]ethanolamine after infection. The incorporation of [14C]ethanolamine was also decreased after 6 hr of infection. When choline was substituted for ethanolamine, a similar, although less pronounced, decrease in incorporation was seen in infected cells compared to mock-infected cells. During abortive infections at 42 C, incorporation of [3H]thymidine into cellular DNA was stimulated, but the incorporation of phospholipid precursors was decreased. Total phospholipid composition and phospholipid acyl group composition were not changed appreciably during abortive or productive infection, regardless of whether the cells were labeled before or after infection. In conclusion, these data indicated that, during herpes simplex virus type 2 infection, the incorporation of lipid precursors into phospholipid was decreased. The stimulation of cellular DNA synthesis previously observed during abortive infection at 42 C was not paralleled by a detectable stimulation of total phospholipid synthesis. Neither productive nor abortive infection resulted in significant phospholipid compositional changes in the host cell; however, both resulted in a marked inhibition of phospholipid synthesis.

Cells, Cultured↗
PubMed1981

Effect of phagocytosis and ionophores on release and metabolism of arachidonic acid from human neutrophils.

Challenge of human neutrophils prelabeled with [3H] arachidonate and [14C] palmitate or [14C]-stearate with opsonized zymosan or the Ca2+ ionophores A23187 or Ionomycin caused the release of [3H], but not [14C], fatty acid. With the ionophores, but not zymosan, considerable conversion of the [3H] arachidonate to hydroxyeicosatetraenoates occurred. Although various isomers were recovered, the 5-hydroxyeicosatetraenoate appeared to be the major product. In these experiments, no [14C] products were detected such as lysophospholipid, diglyceride or monoglyceride. Although no definite statement can be made about the mechanism of release of arachidonate, our data are most easily interpreted as the result of the action of a phospholipase A2.

Anti-Bacterial Agents↗
PubMed1981

Deacylation of dipalmitoyllecithin by phospholipases A in alveolar macrophages.

Optimal conditions in vitro were established for the assay of phospholipases A of Bacillus Calmette Guerin-induced alveolar macrophages that deacylated dipalmitoyllecithin in the alkaline pH range. Sodium deoxycholate and Ca++ were found to stimulate both phospholipases A1 and A2, whereas sodium dodecylsulfate strongly inhibited both enzyme activities. Other detergents like Triton X-100, Triton WR-1339, and Tween-20 activated phospholipase A1, whereas they had no effect on or slightly inhibited the phospholipase A2 enzyme. These phospholipases preferentially removed palmitic acid regardless of the position of palmitic acid on the phospholipid molecule and were more active on phosphatidylcholines than phosphatidylethanolamines. This suggests a role for macrophage phospholipases A in the clearance of saturated lecithins in the pulmonary surfactant complex.

Animals↗
PubMed1981

Aminoacyl fucosides as possible biochemical markers at tumorigenic and metastatic potential in herpes simplex virus type 2-transformed rat cells.

Two classes of aminoacyl fucosides termed FL3 and FL4 were studied as possible markers of tumorigenic and metastatic potential in herpes simplex virus type 2 transformed rat cells. In the present study, clonal cell lines of transformed highly tumorigenic and metastatic (t-REF-G-1.1), weakly tumorigenic and nonmetastatic (t-REF-G-2.1), nontumorigenic (t-REF-G-2.0), and secondary nontransformed rat embryo fibroblast cells were labeled with [3H]fucose, and cell extracts were analyzed for ratio of radioactivity incorporated into FL3 and FL4. Results indicated that, in extracts from t-REF-G-2.0 and nontransformed rat embryo fibroblast cells, the ratios of FL4/FL3 were 5.78 and 5.71, respectively. In contrast, t-REF-G-2.1 cells exhibited a FL4/FL3 ratio of 1.45, while t-REF-G-1.1 cells exhibited a FL4/FL3 ratio of 0.74. In subclonal cell lines isolated from TPA-treated and mock-treated t-REF-G-2.1 cells, the FL4/FL3 ratios correlated with the tumorigenic and metastatic potential of these subclones in newborn syngeneic White Buffalo rats. These data suggested that alterations in fucose-labeled components can be used to predict the tumorigenic and metastatic potential of herpes simplex virus type 2-transformed rat cells.

Aminoglycosides↗
PubMed1981

1-O-Alkyl-sn-glyceryl-3-phosphorylcholines: a novel class of neutrophil stimulants.

1-O-Alkyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine aggregates and degranulates platelets and polymorphonuclear neutrophils. Here, the bioactivities of this platelet-activating factor, its 2-O-ethyl, and its 2-lyso derivatives were examined further. Each phospholipid aggregated and degranulated rabbit platelets and neutrophils with relative potencies of about 10,000 1,000, and 1, respectively. For rabbit neutrophils, and 2-O-acetyl compound was active in nanomolar and lower concentrations; required extracellular calcium and magnesium in order to induce aggregation; and required extracellular calcium and cytochlasin B in order to induce optimal degranulation. Furthermore the 2-O-acetyl and 2-O-ethyl compounds, in concentrations about tenfold higher than those required for rabbit neutrophils, aggregated and degranulated human neutrophils. With reference to these human neutrophil responses, degranulation required, and aggregation was dramatically enhanced by, cytochalasin B. The lysoanalog was unable to induce these response in the human cells. Thus, these lipids represent a novel class of neutrophil stimulants that closely resemble certain chemotactic factors (eg, C5a and synthetic oligopeptides) in their ability to aggregate and degranulate neutrophils and in the influences which calcium, magnesium and cytochalasin B have on their bioactions. Because platelet-activating factor circulates in the blood of rabbits and, perhaps, humans during anaphylaxis and is suspected of being involved in other syndromes such as serum sickness, this lipid may have unique biologic significance: it may act to recruit platelets and neutrophils into the lesions of these and similar pathologic syndromes.

Animals↗