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S Lopez

Publications and source records attributed to S Lopez.

At least 55 records · Page 3Linked to original sources

Presence of proteinase 3 in secretory vesicles: evidence of a novel, highly mobilizable intracellular pool distinct from azurophil granules.

Proteinase 3 (PR3), which is also called myeloblastin, the target autoantigen for antineutrophil cytoplasmic antibodies (ANCA) in Wegener's granulomatosis, is a serine proteinase stored in azurophil granules of human neutrophils. We have previously shown that, in contrast to elastase or myeloperoxidase, PR3 is also expressed at the plasma membrane of a subset of unactivated neutrophils and that a high proportion of neutrophils expressing membrane PR3 is a risk factor for vasculitis. The present study demonstrates that the association of PR3 with the plasma membrane is not an ionic interaction and seems to be covalent. Fractionation of neutrophils shows that, besides the azurophil granules, PR3 could be detected both in specific granules and in the plasma membrane-enriched fraction containing secretory vesicles, whereas elastase and myeloperoxidase were exclusively located in azurophil granules. Electron microscopy confirms that PR3 is present along with CR1 in secretory vesicles as well as in some specific granules. In neutrophils stimulated with an increasing dose of FMLP, membrane PR3 expression increased with the degranulation of secretory vesicles, followed by specific granules, and culminated after azurophil granules mobilization. The presence of a readily plasma membrane-mobilizable pool of PR3 contained in the secretory vesicles might play a relevant role in the pathophysiological mechanisms of ANCA-associated vasculitis.

Autoantigens↗

A large subset of neutrophils expressing membrane proteinase 3 is a risk factor for vasculitis and rheumatoid arthritis.

It has been shown previously that proteinase 3 (PR3), a neutrophil intracellular protease that is the main antigen of antineutrophil cytoplasm (ANCA) autoantibodies, is present on the plasma membrane of a subset of freshly isolated neutrophils. This study shows that the size of this subset of membrane PR3-positive (mPR3+) neutrophils is a stable feature of a given individual, most likely genetically controlled. It ranges from 0 to 100% of neutrophils and allows us to define a new polymorphism in the healthy population, with three discrete phenotypes corresponding respectively to less than 20% mPR3 + neutrophils (mPR3low) or to a mean percentage of 47% (mPR3intermediate) and 71.5% (mPR3high) mPR3+ neutrophils. The frequency of the mPR3high phenotype was significantly increased in patients with ANCA-associated vasculitis (85% versus 55% in healthy subjects). The percentage of mPR3+ neutrophils was not affected by disease activity, relapses, or therapy, and did not reflect in vivo cell activation. In addition, mPR3+ phenotypes were normally distributed in cystic fibrosis patients, indicating that infection and/or inflammation per se do not lead to a high percentage of mPR3+ neutrophils. The frequency of the mPR3high phenotype was not related to anti-PR3 autoimmunization, since it was increased in vasculitic patients regardless of the ANCA specificity (anti-PR3, anti-myeloperoxidase, or unknown). Interestingly, the frequency of the mPR3high phenotype was also increased in patients with rheumatoid arthritis. It was normal in type I-diabetes, a T cell-dependent autoimmune disease. It is proposed here that a high proportion of membrane PR3-positive neutrophils could favor the occurrence or the progression of chronic inflammatory diseases.

Adult↗

Activation of plasminogen activator inhibitor-1 synthesis by phorbol esters in human promyelocyte HL-60--roles of PCKbeta and MAPK p42.

HL-60 cells treated by PMA develop the monocyte adherent phenotype and synthesize plasminogen activator inhibitor type-1 (PAI-1). We focused our study on the identification of the PMA-activated protein kinase C (PKC) isoform and its downstream transduction pathway activating PAI-1 synthesis. Acquisition of the monocytic phenotype was evidenced by cell adherence (90-95%) and a sharp increase of CD 36 and receptor for urokinase plasminogen activator (uPAR) surface expression. Ro 31-8220, a specific inhibitor of PKC, prevented PMA-induced PAI-1 synthesis (mRNA and protein levels) and cell adhesion. To identify the PKC isoform, we took advantage of the HL-525 cell line, an HL-60 cell variant deficient in PKCbeta gene expression. This defect prevents PMA to induce the differentiation process. HL-525 stimulated by PMA did not synthesize PAI-1 nor become adherent. However, in HL-525 cells either pretreated by retinoic acid that reinduces PKCbeta gene expression or transfected with PKCbeta cDNA, PMA significantly activated PAI-1 synthesis and adhesion of cells. Immunoblotting of active Mitogen Activated Protein Kinase (MAPK) p42/p44 in HL-60 cells showed a preferential and sustained activation of the p42 isoform by PMA over the p44 isoform. Ro 31-8220 significantly attenuated this activation. PD 098059 and U0126, both highly specific MEK inhibitors, efficiently prevented PMA-induced PAI-1 synthesis (mRNA and protein levels) and cell adhesion whereas SB203580, a specific inhibitor of stress-activated MAPK p38, did not. Results obtained from HL-60 and HL-525 cells indicate that the PMA-activated transduction pathway of uPAR expression involves a PKC isoform other than PKCbeta. In conclusion, we propose that the pathway PKCbeta-MEK-MAPK p42 is a potential linear route for PAI-1 synthesis leading to morphological changes and adherence linked to PMA-induced differentiation in HL-60 cells.

Carcinogens↗

Characterization of the aldolase B intronic enhancer.

The aldolase B gene is transcribed at a high level in the liver, kidney, and small intestine. This high level of gene expression results from cooperation between a weak but liver-specific promoter and an intronic activator. A deletional study of this activator present in the first intron allowed us to ascribe the maximal enhancer function to a 400-base pair (bp) fragment (+1916 to + 2329). This enhancer is highly liver-specific and enhances the activity of heterologous minimal promoters in a position and distance-independent fashion in transiently transfected Hep G2 hepatoma cells. The aldolase B enhancer is composed of two domains, a 200-bp module (Ba) inactive by itself but which synergizes with another 200-bp module (Bb) that alone retains 25% of the total enhancer activity. The Bb sequence is 76% homologous between human and rat genes and contains several binding sites for liver-enriched nuclear factors. By electrophoretic mobility shift assays, we demonstrated that elements 5 and 7 bind hepatic nuclear factor 1 (HNF1), whereas element 2 binds hepatic nuclear factor 4 (HNF4). A functional analysis of the enhancer whose elements have been mutated demonstrated that mutation of any of the HNF1 sites totally suppressed enhancer activity, whereas mutation of the HNF4-binding site reduced it by 80%.

Animals↗

Pregnancy outcome and weight gain recommendations for the morbidly obese woman.

OBJECTIVE: To compare pregnancy outcomes between morbidly obese and nonobese women and to determine the effect of gestational weight gain on pregnancy outcome in morbidly obese women. METHODS: A retrospective cohort study was conducted comparing 613 morbidly obese and 11,313 nonobese women who were delivered of a singleton live birth. Morbid obesity was defined as a body mass index greater than 35. The incidence of selected perinatal and neonatal outcomes was assessed for the two groups. Multiple logistic regression analysis was used to evaluate the association between morbid obesity and various measures of outcome while controlling for potential confounders. A subanalysis of the morbidly obese patients was performed to assess the effect of gestational weight gain on pregnancy outcome. RESULTS: Morbidly obese patients were more likely to experience pregnancy complications including diabetes, hypertension, preeclampsia, and arrest-of-labor disorders; however, these were not affected by gestational weight gain. Morbidly obese patients were more likely to experience fetal distress and meconium and to undergo cesarean delivery than their nonobese counterparts (P < .05). Weight gains of more than 25 lb were associated strongly with birth of a large for gestational age (LGA) neonate (P < .01); however, poor weight gain did not appear to increase the risk of delivery of a low birth weight neonate. CONCLUSION: Gestational weight gain was not associated with adverse perinatal outcome, but it did influence neonatal outcome. To reduce the risk of delivery of an LGA newborn, the optimal gestational weight gain for morbidly obese women should not exceed 25 lb.

Adult↗

[Acute myopericarditis following laparoscopic treatment of gastroesophageal reflux].

A 32-year-old patient experienced a postoperative acute myopericarditis following laparoscopic surgery for gastro-oesophageal reflux (Toupet's fundoplication). His medical history was unremarkable, apart from controlled arterial hypertension. Peroperative circulation was stable, except a short hypertensive episode at CO2 insufflation, controlled with nicardipine. A myopericarditis occurred at the fourth postoperative hour, with apical and inferior hypokinesia at ventriculography, ST-segment elevation with unremarkable coronary arteriography. The patient was discharged at day seven, with a NSAIDs treatment. Echocardiography three and nine months later postoperatively, showed an apical akinesia and persistence of the ST-segment modification, without clinical symptoms. Complications of laparoscopic fundoplication is either specific to surgery (gastro-oesophageal injury, diaphragmatic injury, mediastinitis, stenosis) or secondary to pneumoperitoneum (pneumothorax, carbon dioxide embolism). In this case, following an apparently uncomplicated laparoscopy and, except a direct cardiac trauma from a laparoscopic instrument, either coronary artery spasm, or pneumopericardium with CO2, or delayed gas embolism, or preoperative "silent" myopericarditis could be the potential cause of this cardiac complication.

Acute Disease↗

Highly purified soybean protein is not hypocholesterolemic in rats but stimulates cholesterol synthesis and excretion and reduces polyunsaturated fatty acid biosynthesis.

The specific effects of soybean protein on lipid metabolism were determined with highly purified soybean protein. At 5 wk of age, growing rats were fed diets containing 20% highly purified soybean protein or casein supplemented or not with 0.1% cholesterol for 2 mo. Plasma and liver lipid composition, fecal steroid excretion and several hepatic enzyme activities were measured. There were no significant dietary protein-related differences in plasma and liver cholesterol concentrations. When diets were cholesterol free, highly purified soybean protein stimulated fecal neutral and acidic steroid excretion associated with concomitantly higher hydroxy methylglutaryl CoA (HMG-CoA) reductase activity, but lower cholesterol 7alpha-hydroxylase activity. Soybean protein lowered the linoleate desaturation index [20:4(n-6)/18:2(n-6)] in liver microsomal lipids and phospholipids. This may have been due to the reduced microsomal Delta6(n-6) desaturase activity in rats fed soybean protein, whereas Delta5(n-6) desaturase activity did not differ between groups fed the two proteins. Cholesterol supplementation (0.1%) did not affect plasma cholesterol but increased liver cholesterol and triacylglycerol concentrations and reduced HMG-CoA reductase activity; this latter effect was greatest in rats fed soybean protein. Cholesterol 7alpha-hydroxylase activity, however, was diminished only in rats fed casein. Desaturase activities, and particularly Delta5(n-6) activity, were lowered by cholesterol supplementation in rats fed both protein diets, including a significantly lower 20:4(n-6)/18:2(n-6) ratio in liver microsomal lipids and liver phospholipids. Thus although dietary proteins have no effect on serum cholesterol in rats, they affect enzyme activities involved in cholesterol metabolism and fatty acid desaturation.

Animals↗

CD43 (sialophorin, leukosialin) shedding is an initial event during neutrophil migration, which could be closely related to the spreading of adherent cells.

Leukosialin is a negatively-charged mucin-like membrane protein of leukocytes. This anti-adhesive molecule prevents uncontrolled cellular interactions and is proteolytically cleaved during neutrophil activation. CD43 is shed in vivo during neutrophil migration to the inflammatory site. We have analysed the decrease in CD43 expression during in vitro adherence of TNF-alpha activated PMN. CD43 was quantitated by flow cytometry on TNF-alpha-activated PMN either maintained in suspension or allowed to adhere then detached with EDTA. Although TNF did not induce significant modification of CD43 expression on suspended cells, we showed that 40% of membrane CD43 is released during neutrophil TNF-induced adhesion to serum-coated plates or endothelial cells, and that migration through the endothelial monolayer did not result in further shedding. Adhesion-blocking anti-beta 2 integrin mAbs prevented CD43 shedding. beta 2 integrin "activation" by anti-CD 18 mAbs or Mn ions did not decrease CD43 expression if adhesion was prevented by stirring. Inhibitors of signal transduction or of cytoskeleton association, which allowed cells to adhere but not to spread, inhibited the shedding of CD43 during adhesion. We conclude that CD43 shedding is not promoted by beta 2 integrins engagement or adhesion but is concomitant with spreading of adherent cells.

1-Methyl-3-isobutylxanthine↗

The localization of guanylyl cyclase-activating proteins in the mammalian retina.

PURPOSE: To explore the distribution of guanylyl cylase-activating proteins 1 and 2 (GCAP1 and GCAP2) in the mammalian retina. METHODS: Cryostat and vibratome vertical sections and wholemount retinas from mouse, rat, cat, bovine, monkey, and human eyes were prepared for immunocytochemistry and viewing by light and confocal microscopy. RESULTS: In all mammalian retinas investigated, intense GCAP1 immunoreactivity (GCAP1-IR) was seen in cone photoreceptor inner and outer segments, cell bodies, and synaptic regions. Intensity of the GCAP1-IR was strong in inner segments of rods in all species but weaker in outer segments-particularly so in primates and cats. GCAP2 immunoreactivity (GCAP2-IR) was weak in bovine, mouse, and rat cones but was intense in human and monkey cones. In all species except primates, GCAP2 staining was intense in rod inner and outer segments. In primates GCAP2-IR was intense in the rod inner segment but faint in the rod outer segment. A striking difference from the GCAP1 pattern of immunoreactivity was seen with GCAP2 antibodies as far as the inner retina was concerned. GCAP2-IR was evident in certain populations of bipolar, amacrine, and ganglion cells in all species. CONCLUSIONS: GCAP1 and GCAP2, which are involved in Ca2+-dependent stimulation and inhibition of photoreceptor guanylyl cyclase, can be detected in mammalian photoreceptor inner and outer segments, consistent with their physiological function. The occurrence of both GCAPs in the synaptic region of the photoreceptors indicates participation of these proteins in pathways other than regulation of phototransduction. The occurrence of GCAP2 in inner retinal neurons is indicative of second-messenger chemical transduction, possibly in metabotropic glutamate, gamma-aminobutyric acid (GABA) receptor, and nitric oxide-activated neural circuits.

Animals↗

Pudendal nerve motor latency correlation by age and sex.

This study was a prospective study, it was undertaken on 172 subjects who had no prior central or peripheral nerve supply pathology and who had not an antecedent of anal surgery. The subjects had a normal value of the sacral reflex latency to be included in this study. In this population the value of the pudendal motor nerve latency was compared by age and sex in order to determine precise norms. There was 92 men whose age adveraged 36 +/- 14.57 years and 80 women with an average age of 55.03 +/- 15.7. The motor latency was obtained by stimulating the nerve by rectal or vaginal tuch-near the sciatic spine with a St Mark's electrod and taking a reading in the intemediate part of the external anal sphincter muscle. The intensity of the stimulation was 70 to 80 mA. The stimulation and the recording was repeteded five both on each side and the shorter latency whose choised. The value of the motor latency taken at the positive peak was analysed statiscally. The average value was 5.52 +/- 1.9 ms on right pudendal nerve and 5.74 +/- 1.6 ms on the left in male subjects and 6.16 +/- 1.8 in the right pudendal nerve and 6.42 +/- 1.96 on the left in female subjects. The values on right pudendal nerve latency varied from 4.9 +/- 1.28 ms in men and 4.76 +/- 1.6 ms. in women at under 28 years and to 5.06 +/- 2.06 ms in men and 7.7 +/- 1.8 ms in women at over 70 years. The values on the left side varied from 5.53 +/- 1.5 ms in men and 4.78 +/- 1.35 ms in women at under 28 years and to 5.06 +/- 2.06 ms in men and 8.47 +/- 1.95 ms in women at over 70 years. In men population, the value of the motor latency of the pudendal nerve is not correlated with age. In women population, the value is correlated with age.

Adult↗

The mental health and adjustment of immigrant and refugee children.

Although parents may make decisions to leave their homes, either willingly in the hope of improving their lives or involuntarily to escape danger and seek safety for themselves and their families, it is never a voluntary decision for the child. The economic, political, social, and other contextual issues associated with migration are as significant in predicting the child's adjustment to his or her new circumstances as his or her physical and psychological endowment. This article addresses these issues and suggests that particular consideration be given to children whose migration was punctuated by life-threatening danger or whose families were overwhelmed by the stresses of migratory experiences. Child and adolescent psychiatrists and other well-trained mental health professionals can further the understanding of the interactions among the child, family, and new community, which can promote or hinder the process of adaptation to the new setting.

Acculturation↗

Silencer activity in the interferon-A gene promoters.

Interferon-A (IFN-A) differential gene expression is modulated by a complex interplay between cis-acting DNA elements and the corresponding specific trans-regulating factors. Substitutions in the proximal virus-responsive element of the interferon-A (IFN-A) promoters contribute to their differential gene expression. The 5' distal silencing region in the weakly virus-inducible murine IFN-A11 gene has been previously delimited. DNase I footprinting experiments and transient gene expression assays demonstrate identical silencing activity in equivalent regions of the genes for IFN-A11 and IFN-A4 promoters. A minimal 20-mer distal negative regulatory element (DNRE) in both promoters is necessary and sufficient for the silencing and a region in the highly inducible IFN-A4 promoter located between the silencer and the virus-responsive element overrides the silencer activity. Mutations in the central region of the DNRE, causing derepression, also altered the formation of one of the two major DNA-protein complexes. One of these contains a protein related to or identical to the high mobility group I(Y) proteins, while the other complex contains a major protein present in uninduced and virus-induced cells with a molecular mass of 38 kDa, which may be related to the silencer activity. Similar DNREs are present in other virus-uninducible IFN-A promoters, and these data suggest that a common silencer may mediate the transcriptional repression in different genes of this family.

Base Sequence↗

[Electrophysiologic studies in the descending perineum in women].

Seventy five female patients (mean age: 55 +/- 13 years) were included into the study. Electromyography of the perineum with study of the intramuscular activity of the external anal sphincter was done and measures of the sacral reflex latency were obtained by stimulation of the cavernous nerve of the clitoris, recording in the external anal sphincter muscle. Neurogenic syndromes of pudendal nerve either isolated or associated with muscular disorders have been shown to be correlated with descending perineum. In our study, we investigated whether a history of obstetrical or surgical interventions is related to the occurrence of this syndrome. We did not find any significant relationship.

Adult↗

Identification of a T-helper cell epitope on the rotavirus VP6 protein.

In this work, we have studied the T-helper (Th)-cell response against rotavirus, in a mouse model. Adult BALB/c mice were inoculated parenterally with porcine rotavirus YM, and the Th-cell response from spleen cells against the virus and two overlapping fragments of the major capsid protein VP6 (VP6(1-192) and VP6(171-397)) were evaluated in vitro. The Th cells recognized the YM virus and the two protein fragments, suggesting that there are at least two Th-cell epitopes on the VP6 molecule. To study the specificity of Th cells against VP6 at the clonal level, we established two Th-cell hybridomas cross-reactive for the VP6 protein of rotavirus strains YM and SA11. Both hybridomas recognized the VP6(171-397) polypeptide, and a synthetic peptide comprising the amino acids 289 to 302 (RLSFQLVRPPNMTP) of YM VP6 in the context of the major histocompatibility complex class II IEd molecule. The Th-cell hybridomas recognized rotavirus VP6 in a highly cross-reactive fashion, since they could be stimulated by eight different strains of rotavirus, including the murine rotavirus EDIM, that represent five G serotypes and at least two subgroups. The amino acid sequence of the VP6 epitope is highly conserved in most group A rotavirus strains sequenced so far. On the other hand, it was found that Th cells specific for the VP6 epitope may constitute an important proportion of the total polyclonal Th-cell response against rotavirus YM in spleen cells. These results demonstrate that VP6 can be a target for highly cross-reactive Th cells.

Animals↗

Vanadate, but not insulin, inhibits insulin receptor gene expression in rat hepatoma cells.

Insulin and vanadate treatments have recently been shown to reverse the overexpression of the hepatic insulin receptor (IR) gene in streptozotocin-induced diabetic rats. To better understand the mechanisms underlying these effects, the abilities of insulin and vanadate to affect IR gene expression have been comparatively examined in Fao hepatoma cells, an insulin-responsive cell line. Exposure of Fao cells to insulin (1 microM) or vanadate (500 microM) for 24 h led to a 2-fold decrease in IR number in total cellular membranes. Insulin treatment did not affect IR messenger RNA (mRNA) level regardless of time of exposure and concentration. In contrast, vanadate treatment caused a time- and dose-dependent decrease in IR mRNA level, which was maximal (4-fold change) after a 24-h exposure to 500 microM vanadate and was fully reversible. Insulin treatment increased from 28 to 39% the relative expression of isotype A IR mRNA, but vanadate treatment did not significantly affect this parameter. Vanadate treatment did not modify mRNA half-life (3.5 h) in 5, 6 dichlorobenzimidazole riboside-treated cells but decreased by 4-fold the transcriptional activity of the IR gene. These data show for the first time that, although both insulin and vanadate decrease total cellular IR number in Fao cells, only vanadate decreases IR mRNA level. It does so by inhibiting transcription of the IR gene, suggesting an action on the gene promoter which could be mediated by changes in the level of expression and/or of phosphorylation of trans-acting factors.

Animals↗

A multicenter, randomized, double-blind, placebo-controlled trial of influenza immunization in multiple sclerosis.

We determined the effect of influenza vaccine in patients with relapsing/remitting MS. Considerable controversy surrounds the question of whether to administer influenza vaccines to MS patients. Prevention of a febrile viral illness is clearly desirable in MS, and previous studies suggest that immunization is safe. Despite this, many clinicians avoid vaccination because they fear precipitating an MS exacerbation. We conducted a multicenter, prospective, randomized, double-blind trial of influenza immunization in patients with relapsing/remitting MS. In the autumn of 1993, 104 patients at five MS centers received either standard influenza vaccine or placebo. Patients were followed for 6 months for evaluation of neurologic status and the occurrence of influenza. Influenza was operationally defined as fever > or = 38 degrees C in the presence of coryza, cough, or sore throat at a time when the disease was present in the community. Attacks were defined in the standard manner, requiring objective change in the examination. Patients were examined at 4 weeks and 6 months after inoculation and were contacted by telephone at 1 week and 3 months. They were also examined at times of possible attacks but not when they were sick with flu-like illness. Three vaccine patients and two placebo patients experienced attacks within 28 days of vaccine (no significant difference). Exacerbation rates in the first month for both groups were equal to or less than expected from published series. The two groups showed no difference in attack rate or disease progression over 6 months. Influenza immunization in MS patients is neither associated with an increased exacerbation rate in the postvaccination period nor a change in disease course over the subsequent 6 months.

Double-Blind Method↗

Leukosialin (CD43, sialophorin) redistribution in uropods of polarized neutrophils is induced by CD43 cross-linking by antibodies, by colchicine or by chemotactic peptides.

We investigated a possible association of leukosialin (CD43), the major surface sialoglycoprotein of leukocytes, with neutrophil cytoskeleton. We first analysed the solubility of CD43 in Triton X-100 and observed that CD43 of resting neutrophils was mostly soluble. The small proportion of CD43 molecules, which 'spontaneously' precipitated in Triton, appeared associated with F-actin, as demonstrated by the fact that this insolubility did not occur when cells were incubated with cytochalasin B or when F-actin was depolymerized with DNase I in the Triton precipitate. Cell stimulation with anti-CD43 mAb (MEM59) enhanced this CD43-cytoskeleton association. By immunofluorescence as well as by electron microscopy, we observed a redistribution of CD43 on the neutrophil membrane, initially in patches followed by caps, during anti-CD43 cross-linking at 37 degrees C. This capping did not occur at 4 degrees C and was inhibited by cytochalasin B and by a myosin disrupting drug butanedione monoxime, thus providing evidence that the actomyosin contracile sytem is involved in the capping and further suggesting an association of CD43 with the cytoskeleton. Some of the capped cells exhibited a front-tail polarization with CD43 caps located in the uropod at the rear of the cell. Surprisingly, colchicine and the chemotactic factor fNLPNTL which induce neutrophil polarization associated with cell motility, also resulted in a clustering of CD43 in the uropod, independently of a cross-linking of the molecule by mAbs. An intracellular redistribution of F-actin, mainly at the leading front and of myosin in the tail, was observed during CD43 clustering induced by colchicine and in cells polarized by anti-CD43 mAbs cross-linking. We conclude that neutrophil CD43 interacts with the cytoskeleton, either directly or indirectly, to redistribute in the cell uropod under antibodies stimulation or during cell polarization by colchicine, thus highly suggesting that CD43 may be involved in cell polarization.

Actins↗