Activation of peritoneal macrophages during the prediabetic phase in low-dose streptozotocin-treated mice.
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Animals↗
Biomedical subjects
M Conde
Publications and source records attributed to M Conde.
Nicotinamide inhibits inducible nitric oxide synthase enzyme activity in macrophages by allowing nitric oxide to inhibit its own formation.
Nitric oxide (NO) production by macrophages is mainly regulated by induction of nitric oxide synthase (iNOS) by cytokines and microbial products. Nicotinamide (NIC) inhibits NO production by activated macrophages in a dose dependent manner. NIC also inhibits NOS enzyme activity in extracts from activated macrophages. The inhibition was noncompetitive with L-arginine (Ki 13.37 +/- 4.40 mM, n=3), uncompetitive versus NADPH (Ki 3.06 +/- 0.17 mM, n=3) and tetrahydrobiopterin. Finally, the inhibition by nicotinamide was fully reversed by scavenging NO with hemoglobin. We suggest that NIC acts by allowing NO to inhibit its own formation.
Animals↗
[Deafness secondary to lumbar puncture].
INTRODUCTION AND OBJECTIVE: Disorders of hearing have been described in patients who have undergone lumbar puncture. The lower frequencies are most affected, temporarily and with spontaneous recovery in most cases. It would seem that the cochlea aqueduct (AC) (an anatomical structure found in the internal ear) is the part involved in the pathogenesis of this infrequent complication. The object of this paper is to review the different hypothesis put forward by various authors on the subject, emphasizing the one which seems most probable. At the same time, we offer a new vision of this little known and often forgotten anatomical structure of the internal ear. The anatomy and physiology of the AC is considered, studying the part played by the labyrinth fluid when the patient undergoes an operation involving the cerebro-spinal fluid (CSF) or the subarachnoid space. CONCLUSIONS: Whenever this technique is to be used, it is essential to obtain a clinical history to find out whether the patient has, or has had, any problems of hearing, and if so of what type. All patients should be warned of the possibility of deafness, in most cases temporary, and if the patient has hydrops endolymphaticus (syndrome of Ménière) of the high risk of worsening his hearing threshold. We therefore recommend precise evaluation of the use of this technique.
Audiometry↗
Enhancement of Antigen-specific functional responses by neutrophils from allergic patients.
It has been demonstrated that neutrophils from healthy donors or from patients with inflammatory disorders can bind immunoglobulin (Ig) E proteins through binding to Mac-2/epsilon bp. Functional responses to allergens were assessed by measuring the respiratory burst and intracellular Ca2+ levels, and binding of allergens to neutrophils was assessed by flow cytometry analysis and fluorescence microscopy. In this article, we demonstrate that neutrophils sensitized to specific allergens (from allergic patients), but not from healthy donors, are sensitive to allergens of the same type as those that produce clinical allergic symptoms. The activation of neutrophils was analyzed by the induction of a respiratory burst that was detected with luminol-dependent chemiluminescence. Intracellular Ca2+ levels increased parallel to those of the inducing allergens. In addition, the specific binding of allergens on the cell surface was revealed by flow cytometry and allergen-FITC-labeled staining analyses. The present data suggest a restricted recognition of allergen by sensitive neutrophils, probably associated with the specific binding of the allergen to its corresponding IgE molecule, which is bound to the Mac-2/epsilon bp structure. These findings demonstrate a functional role of allergen-associated neutrophils during the allergic state.
Allergens↗
Anti-CD69 antibodies enhance phorbol-dependent glucose metabolism and Ca2+ levels in human thymocytes. Antagonist effect of cyclosporin A.
The human activation antigen CD69 is an early inducible surface glycoprotein acquired by T cells in the thymus at the stage of positive selection and during activation of mature lymphoid cells both in vivo and in vitro. We have studied the regulatory influence of CD69 activation pathway on the glycolytic process and transduction signals of thymocytes. Treatment of human thymocytes with different anti-CD69 monoclonal antibodies (mAbs), in the presence of submitogenic doses of phorbol ester, produced an enhanced release of lactate without significant alterations in Fru 2,6-P2 levels or phosphofructokinase-2 (PFK-2) and pyruvate kinase activities. A small increase in phosphofructokinase-1 (PFK-1) activity was also detected. Furthermore, anti-CD69 mAb increased the glucose detritiation from [2-3H] and [3-3H]glucose, thus indicating an enhanced flux through hexokinase and PFK-1 steps. In addition, de novo synthesis of diacylglycerol and intracellular Ca2+ levels increased after anti-CD69 mAb treatment. The stimulatory effects of anti-CD69 mAb on both glycolysis and Ca2+ levels were inhibited by cyclosporin A. Because CD69 molecules are present in certain subset populations of immature thymocytes, the ability of anti-CD69 mAb to stimulate the glycolysis, the synthesis of diacylglycerol and the intracellular Ca2+ levels suggest that the activation signals delivered through CD69 molecules could play a role in the thymus cells maturation.
Antibodies, Monoclonal↗
Streptozotocin-induced diabetes increases fructose 2,6-biphosphate levels and glucose metabolism in thymus lymphocytes.
Acute effect of streptozotocin-induced diabetes on several parameters of glucose metabolism was investigated in thymus lymphocytes (thymocytes). The cells from diabetics rats accumulated in vitro about 2-fold more fructose 2,6-bisphosphate (Fru-2, 6-P2) in the presence of increasing glucose concentration than cells from normal rats. An increased production of lactate was also observed. Phosphofructokinase-1 (PFK-1) and phosphofructokinase-2 (PFK-2) activities were enhanced in cells from diabetic rats compared with those from normal rats. [U-14C]glucose incorporation into glycogen was also increased in cells from diabetic rats and the 14CO2 liberation was lesser than in cells from normal animals. From these data it may be concluded that the response of thymocytes to streptozotocin-induced diabetes is similar to that observed in other extrahepatic tissues.
Animals↗
Protection from nicotinamide inhibition of interleukin-1 beta-induced RIN cell nitric oxide formation is associated with induction of MnSOD enzyme activity.
We have studied the long-term effects of nicotinamide (NIC) on the synthesis of NO by insulin producing cells. NIC delays the formation of nitrite by interleukin (IL)-1 beta-(IL-1, 25 U/ml)-stimulated RINm5F cells, and previous exposure of cells to IL-1 for 15 h prevents this effect. The delay is associated with a lack of cytokine-induced inducible nitric oxide synthase (iNOS) enzyme activity in cell extracts. NIC (20 mM) inhibits NO synthase (NOS) activity in extracts from cells incubated with IL-1 for 6 h and 24 h, and oxyhemoglobin counteracts this inhibition. Hence, NIC could scavenge O2- and allow NO to inhibit the enzyme. The NO donor SIN-1 inhibits in a concentration-dependent manner iNOS activity, and the effect is potentiated by NIC. In intact cells, protection from NIC is associated with IL-1-induced expression of MnSOD activity, and reversible blockade of iNOS expression with pyrrolidine dithiocarbamate counteracts the NIC effect. We conclude that O2- plays a role in preventing NO inhibition of iNOS. The loss of this action coincides with the induction of MnSOD enzyme activity. In addition, the stimulation by NIC of IL-1-induced nitrite production in pyrrolidine dithiocarbamate-treated cells is a novel action that should be considered when the drug is proposed as potential agent for the prevention of insulin-dependent diabetes mellitus.
Animals↗
Respiratory burst is decreased by human hyperlipemic serum in rat peritoneal macrophages.
The effect of hyperlipemic human serum on superoxide anion (O2-) production by rat peritoneal macrophages was investigated. Phorbol myristate acetate (PMA)-stimulated O2- production was inhibited when cells were preincubated with hyperlipemic human serum. This inhibition was specifically carried out by a lipid fraction and was dependent on both cholesterol and triglyceride serum levels. This inhibitory effect was not exerted by a direct effect on NADPH-oxidase activity, nor by a putative superoxide dismutase activity present in the serum. With human neutrophils, we observed a decreased mobility of the cytosolic factor p47-phox to the membrane during the activation process, caused by hyperlipemic serum. We did not find any effect of hyperlipemic serum on NO2- production by cultured rat macrophages. These results suggest that a pathological increase of circulating plasma lipids may be associated with an impaired inflamatory capacity of macrophages.
Animals↗
Thrombin-stimulated phospholipase C activity is inhibited without visible delay by a rapid increase in the cyclic GMP levels induced by sodium nitroprusside.
Different drugs that elevate the cGMP levels inhibit the agonist-induced platelet activation. The mechanisms of action of cGMP probably include inhibition of both phospholipase C and the increase in intracellular Ca2+ concentration, and these effects seem to be mediated by cGMP-dependent protein kinases. However, in most studies, cells were preincubated with nitrovasodilators before stimulation. The effect of the preincubation with sodium nitroprusside before stimulation or the simultaneous addition of sodium nitroprusside and thrombin has been compared. The simultaneous addition of sodium nitroprusside and thrombin was able to inhibit without any significant delay the platelet aggregation. This rapid effect was correlated with an inhibition of both the maximum increase in intracellular Ca2+ concentration and the phospholipase C activity. Also, the simultaneous addition of sodium nitroprusside and thrombin clearly accelerated the decline in the Ca2+ signal, which was not observed in platelets preincubated with sodium nitroprusside. The rapid inhibition induced by sodium nitroprusside was correlated with a rapid and significant increase in the cGMP levels and reversed when platelets were pretreated with methylene blue. The inhibitor of cAMP-dependent protein kinase Rp-8-(4-chlorophenylthio)-adenosine-3',5'-cyclic monophosphorothioate was able to abolish nearly completely the inhibitory effect induced by sodium nitroprusside independent of the protocol used. Thus, the rapid inhibition induced by sodium nitroprusside seems to be induced by a rapid phosphorylation-dependent mechanism. In addition, both cGMP- and cAMP-dependent protein kinase seem to be involved; however, the cAMP-dependent protein kinase seems to be more important.
Calcium↗
Decrease in free-radical production with age in rat peritoneal macrophages.
The respiratory-burst reaction has been studied in rat peritoneal macrophages of different ages (3, 12 and 24 months) using phorbol 12-myristate 13-acetate (PMA) to stimulate NADPH oxidase. Production of O2-. and H2O2 decreased with age (about 50 and 75% respectively); however, no difference in NADPH oxidase activity was found. NO. production was also reduced with age (40%). Furthermore, a progressive and significant decrease in the pentose phosphate flux was detected as a function of age in control and PMA-stimulated macrophages. The NADPH/NADP+ ratio decreased with age in control and PMA-stimulated macrophages. Glucose uptake was lower in middle-aged (12 months) and old (24 months) animals but no differences were found between these groups.
Aging↗
Effect of thimerosal and other sulfhydryl reagents on calcium permeability in thymus lymphocytes.
We have studied the effects of thimerosal, a mercurial compound extensively used as a preservative, as well as other sulfhydryl reagents (e.g. p-hydroxymercurybenzoate, hydrogen peroxide, bromophenacyl bromide, and mercuric chloride) on Ca2+ homeostasis and the redox status of sulfhydryl groups in thymus lymphocytes. They all induced an increase in [Ca2+]i which was blocked with dithiothreitol, suggesting that they act via the oxidation or blockade of sulfhydryl groups. [Ca2+]i increase could be directly related to the effect of the different reagents on cellular protein sulfhydryl content. Experiments with ethidium bromide indicate that the observed rise in [Ca2+]i was not due to a non-specific increase in membrane permeability. Thimerosal differs from the other agents studied in its oxidative properties, which is probably linked to the production of a potent reductor molecule, thiosalicylic acid, which may modulate its oxidative capacity.
Animals↗
Modulation of phorbol ester-induced respiratory burst by vanadate, genistein, and phenylarsine oxide in mouse macrophages.
The effect of the inhibitors of tyrosine phosphatase (vanadate and phenylarsine oxide) and of an inhibitor of tyrosine kinase (genistein) on O2.- production in mouse peritoneal macrophages was examined. Vanadate and phenylarsine oxide produced a dose-dependent inhibition of phorbol myristate acetate (PMA)-induced O2.- production, whereas genistein potentiated O2.- production triggered by phorbol ester. Vanadate had no effect on the respiratory burst in human neutrophils challenged with fMLP, in agreement with previously published data on human intact neutrophils. It did not alter reduced nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase activity in membrane preparations of mouse peritoneal macrophages. These data suggest that the phosphorylation of protein(s) in tyrosine residues blocked the PMA-dependent respiratory burst in mouse macrophages.
Animals↗
Inhibitory effect of cyclosporin A and FK506 on nitric oxide production by cultured macrophages. Evidence of a direct effect on nitric oxide synthase activity.
Casein-elicited peritoneal macrophages from mice were cultured either alone or with interferon-gamma (IFN-gamma) and bacterial lipopolysaccharide (LPS), and the effect of cyclosporin A (CsA) and FK506 on NO2- production (due technical difficulties NO2- was taken as the index for NO) was analysed. We observed an inhibitory effect of CsA and FK506 on NO2- production. The IC50 for NO2- production by casein-elicited macrophages was 0.1 microgram/ml for CsA and 0.3 microgram/ml FK506. The effect of both drugs was dose-dependent and was more clear in non-stimulated macrophages. The presence of IFN-gamma and LPS in the culture increased NO2- production by casein-elicited macrophages and partially eliminated the inhibition exerted by CsA and FK506. Both drugs acted directly on the nitric oxide synthase (NOS), since CsA and FK506 reduced by 35% and by 17%, respectively, NOS activity in the crude cytosolic fraction. However, CsA and FK506 did not alter 14CO2 production from [1-14C]glucose, suggesting that the pentose monophosphate pathway activity was not modified. These data add new insight into the interpretation of the immunosuppressive properties of both drugs.
Amino Acid Oxidoreductases↗
Cyclosporin A antagonizes phenylephrine, oxytocin and angiotensin effects on glucose metabolism in rat thymus lymphocytes.
Effects of phenylephrine, oxytocin and angiotensin on fructose 2,6-bisphosphate (Fru 2,6-P2) content and glycolytic parameters were studied in incubated thymus lymphocytes. These hormones modified Fru 2,6-P2 content dependent upon the energetic status of the cells. In non-preincubated thymus lymphocytes (with relatively high levels of glycogen and ATP), phenylephrine, oxytocin and angiotensin depressed Fru 2,6-P2 content in a dose-dependent manner. The opposite was found when the cells were preincubated for 2 h without substrates (low levels of ATP and glycogen). Changes in lactate release were less evident, but significant. Phenylephrine did not modify the maximal activities of phosphofructokinase (PFK)-1 or PFK-2. However, both submaximal PFK-1 and PFK-2 activities were inhibited by phenylephrine, and the response to exogenous Fru 2,6-P2 on PFK-1 was also altered. The activities of Fru 1,6-P2 and pyruvate kinase were not modified by phenylephrine or A23187 treatment. Simultaneous presence of Cyclosporin A (CsA), an immunosuppressive drug, antagonizes the alpha-adrenergic effect on Fru 2,6-P2 content. CsA alone did not alter basal levels of ATP, hexose phosphate or Fru 2,6-P2, and its opposing effect to alpha-agonist was dose-dependent. CsA cannot change the positive action of PMA or the negative action of A23187 on Fru 2,6-P2 content. The present data suggest that CsA acts prior to calcium liberation and protein kinase C activation. Different possible molecular models are discussed.
Adenosine Triphosphate↗
Inhibitory effect of interferon-alpha on respiratory burst and glucose metabolism in phagocytic cells.
Anion superoxide (O2-) production and glucose metabolism was studied in murine macrophages following in vivo or in vitro treatment with human recombinant interferon-alpha 2b (IFN-alpha 2b). The PMA-dependent O2- production was inhibited by IFN-alpha 2b in a concentration- and time-dependent manner. NO2- production by macrophages in culture was slightly inhibited (about 16%) at 30 nM IFN-alpha and a clear decrease (35%) was obtained with 150 nM IFN-alpha. Low doses (0.3 and 3 nM IFN-alpha) had no effect. Also, IFN-alpha 2b inhibited lactate release and 3H2O production from [2-3H] and [3-3H]glucose in macrophages isolated after in vivo treatment for 24 h. The data support an inhibitory role of IFN-alpha in the metabolic activation of macrophages and suggest a putative mechanism for the inhibition of some macrophage functions as previously reported.
Animals↗
Activation of peritoneal macrophages during the prediabetic phase in low-dose streptozotocin-treated mice.
Glucose metabolism and the production of O2- and NO2- have been studied in peritoneal macrophages from mice injected with 5 subdiabetogenic doses of streptozotocin. On day 12 after beginning of the treatment, peritoneal macrophages produced significantly higher amounts of lactate than macrophages from control mice. In addition, NO2- release and phorbol ester-induced O2- production were significantly augmented in macrophages from streptozotocin-treated mice. gamma-Interferon induced in a dose-dependent manner the activity of NO synthase only in macrophages from streptozotocin-treated mice. These data show for the first time that peritoneal macrophages from streptozotocin-treated mice are activated and produce effector molecules such as O2- and .NO which could participate in the destruction of pancreatic islets.
Amino Acid Oxidoreductases↗
Streptozotocin-induced diabetes increases fructose 2,6-bisphosphate levels and glucose metabolism in rat macrophages.
The acute effects of streptozotocin-induced diabetes on several parameters of glucose metabolism were investigated in rat peritoneal macrophages. These cells accumulated in vitro about twofold more fructose 2,6-bisphosphate in the presence of increasing glucose concentration than cells from normal rats, and an increased production of lactate was observed. Phosphofructokinase-1, phosphofructokinase-2, hexokinase, and pyruvate kinase activities were increased in cells from diabetic rats compared with those from normal rats. Transport of 2-deoxy-D-glucose was increased in cells from diabetic rats. [U-14C]Glucose incorporation into glycogen was also increased in cells from diabetics and the 14CO2 liberation was less than in cells from normal animals. Moreover, macrophages from diabetics did not possess a more active pentose phosphate pathway (measure with [1-14C]glucose oxidation) nor a greater production of superoxide anion (index of activation of macrophages) than in cells from normal animals.
Animals↗
[Vaccination against measles at 6 months of age].
Measles immunization with the Edmonston Zagreb stain was carried out in 71 six-month-old infants. Proportions of subjects with immunity were 91% among the 47 subjects retested before one year of age and 100% among the 28 subjects retested between two and three years of age. These results support the WHO recommendation that measles immunization should be given at the age of six months. The concerns expressed by some about possible adverse effects of early measles immunization (decreased immune defenses) are discussed, as well as the transfer of maternal antibodies and persistence of these antibodies in the child. The obstacles to such studies in developing countries, including the need for repeated phlebotomies with centrifugation of specimens and freezing of sera, could be circumvented by the use of filter paper dried blood spot samples which seem to provide reliable results although with values somewhat lower than those found in frozen sera.
Antibodies, Viral↗