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Biomedical subjects

I Ramis

Publications and source records attributed to I Ramis.

At least 19 recordsLinked to original sources
PubMed1998

[Nitric oxide synthase activity in nasal mucosa].

Nitric oxide (NO) plays an important regulatory role in airway function and seems to be implicated in the pathophysiology of several airway diseases. We studied the presence of NO synthase activity in human nasal mucosa and nasal polyp tissues obtained from patients undergoing septoplasty or polypectomy, respectively. NO synthase activity was quantified in tissue homogenates using citrulline release assay and was located in tissue sections using NADPH-diaphorase histochemistry. The results indicated that nasal polyps contain higher levels of total NO synthase activity than nasal mucosa tissue. In addition, nasal polyps contained mainly inducible NO synthase activity whereas all NO synthase activity detected in the nasal mucosa was in constitutive form. In both cases, NO synthase activity was localized in epithelial cells. In view of these results, we conclude that NO may be an important inflammatory mediator in the respiratory system and that the epithelium may be a source of NO production.

Adult↗
PubMed1997

The assessment of biomarkers to detect nephrotoxicity using an integrated database.

Groups of industrial workers exposed to heavy metals (cadmium, mercury, and lead) or solvents were studied together with corresponding control groups. The cohorts were collected from several European centers (countries). Eighty-one measurements were carried out on urine, blood, and serum samples and the results of these analyses together with questionnaire information on each individual were entered into a central database using the relational database package Rbase. After the completion of the database construction phase, the data were exported in a format suitable for analysis by the statistical package SAS. The potential value of each test as an indicator of nephrotoxicity was then assessed. Rigorous exclusion criteria were applied which resulted in the elimination of some tests and samples from the dataset. The measurable contributions of smoking, gender, metal exposure, and site were either singly or in combination assessed by biomarkers for nephrotoxicity. The parameters measured included three urinary enzymes, six specific proteins, total protein, two extracellular matrix markers, four prostaglandins and anti-GBM antibodies, and beta 2-microglobulin in serum. The most sensitive renal tests included the urinary enzymes N-acetyl-beta-D-glucosaminidase (NAG) and intestinal alkaline phosphatase (IAP), brush border antigens, and urinary low-molecular-weight proteins. Of the newer tests investigated the prostaglandins were the most promising. Different patterns of biomarker excretion were observed following exposure to lead, cadmium, or mercury. The dataset provides a unique repository of data which could provide the basis of an enlarging source of information on normal human reference ranges and on the effects of exposure to toxins and the use of biomarkers for monitoring nephrotoxicity.

Biomarkers↗
PubMed1996

Interleukin-3 in bronchial biopsies from nonasthmatics and patients with mild and allergen-induced asthma.

Cytokines, such as interleukin-3 (IL-3), have been suggested to play an important role in mediating the increased number of airway eosinophils and metachromatic cells in patients with even mild asthma. We used immunohistochemistry to determine the presence of IL-3 protein in bronchial biopsies from nonasthmatics (n = 10) and subjects with mild (n = 8) and allergen-induced (n = 7) asthma. We also examined whether IL-3 was related to airway eosinophil number and activation, the number of airway metachromatic cells, or airway function. We found that the number and activation of eosinophils and the number of metachromatic cells were increased in the airways of asthmatics, compared with nonasthmatics, with further increases evident after allergen challenge. IL-3 protein was localized primarily to the epithelium in nonasthmatic and asthmatic subjects, with no difference apparent between groups or after allergen inhalation challenge. The extent of staining for IL-3 in the tissue was not correlated with eosinophil number or activity, metachromatic cell number, airway responsiveness, or the severity of the late asthmatic response. This study provides the first demonstration of IL-3 protein localization in bronchial tissue from human airways. The results suggest that the increases in eosinophils and metachromatic cells associated with mild and allergen-induced asthma occur independent of IL-3.

Adult↗
PubMed1996

Differential activity of nitric oxide synthase in human nasal mucosa and polyps.

Nitric oxide (NO) plays an important regulatory role in airway function and seems to be implicated in the pathophysiology of several airway diseases. To better understand the involvement of NO in the upper airways, we examined the presence of nitric oxide synthase (NOS) activity in human nasal mucosa and nasal polyp tissues. Nasal mucosa was obtained from seven patients undergoing septoplasty, and nasal polyps came from nine patients following polypectomy. NOS activity was quantified in tissue homogenates using the citrulline release assay and localized in tissue sections using reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase histochemistry. The results showed that nasal polyps (n = 9) contained higher levels of total NOS activity (mean +/- SD 5.94 +/- 5.71, range 1.29-18.0 pmol.min-1.mg protein) than nasal mucosa tissues (n = 7) (0.28 +/- 0.22, range 0.01-0.57 pmol.min-1.mg protein). In addition, nasal polyps mainly contained inducible NOS activity (4.67 +/- 4.57, range 1.23-15.5 pmol.min-1.mg protein) whereas in nasal mucosa all NOS activity detected was in constitutive form. In both cases, NOS activity was localized in the epithelial cells. Since NO synthase is induced in inflamed upper airways, we conclude that NO may be an important inflammatory mediator in the respiratory system and that the epithelium may be a source of NO production in the human upper airways.

Adult↗
PubMed1996

Development and validation of new screening tests for nephrotoxic effects.

Within the framework of an European Commission-funded project, groups of industrial workers exposed to heavy metals (cadmium, mercury and lead) or solvents were studied together with corresponding control groups. Eighty-one measurements were carried out on urine and serum samples and the scientific results together with individual questionnaire information were entered into a central database. Data obtained was assessed centrally and individually in subsidiary studies. The measurable contributions were assessed either singly or in combination, of smoking, gender, metal exposure and site, to nephrotoxicity. The potential value of each test as an indicator of nephrotoxicity was then assessed on the basis of sensitivity and specificity. A number of new tests including prostaglandins and for extracellular matrix components were investigated as well as established tests for renal damage and dysfunction. The data obtained from this comprehensive study emphasises the value of noninvasive biomarkers for the early detection of nephrotoxicity due to environmental toxins. The urinary profile varied with the type of environmental/occupational toxin. By careful selection of a small panel of markers they can be used to indicate the presence of renal damage, the principal region affected, and to monitor the progress of disease and damage. Biomarkers were also used to confirm and tentatively establish safe exposure levels to nephrotoxins.

Biomarkers↗
PubMed1995

In vitro release of arachidonic acid metabolites, glutathione peroxidase, and oxygen-free radicals from platelets of asthmatic patients with and without aspirin intolerance.

BACKGROUND: An abnormal platelet release of oxygen-free radicals has been described in acetylsalicylic acid (aspirin)-induced asthma, a finding which might suggest the existence of an intrinsic, specific platelet abnormality of arachidonic acid metabolism in these patients. The objective of this study was to evaluate platelet arachidonic acid metabolism in asthmatic patients with or without intolerance to aspirin. METHODS: Thirty subjects distributed into three groups were studied: group 1, 10 healthy subjects; group 2, 10 asthmatic patients with aspirin tolerance; and group 3, 10 aspirin-intolerant asthmatics. Platelets were isolated from blood, preincubated with 3H-arachidonic acid for 30 minutes and then incubated for 10 minutes with platelet activating factor (PAF) and aspirin. Cyclo-oxygenase (thromboxane, PGE2, PGF2 alpha, and HHT) and lipoxygenase (12-HETE) arachidonic acid metabolites were measured by high pressure liquid chromatography. Release of oxygen free radicals after incubation with PAF and aspirin was measured by chemiluminescence. Platelet levels of glutathione peroxidase (GSH-Px) were also measured using spectrophotometry. RESULTS: Platelets from aspirin-intolerant asthmatic patients produced higher quantities of arachidonic acid metabolites than the control group at baseline conditions. This increase was significant only for lipoxygenase products. No differences were found amongst the three groups in the response of arachidonic acid metabolism to PAF and aspirin. Incubation with aspirin but not with PAF caused an increase in oxygen-free radical production in aspirin-intolerant patients whereas in aspirin-tolerant patients PAF, rather than aspirin, was the more potent stimulus for oxygen-free radical production. No differences in GSH-Px levels were found amongst the three groups. CONCLUSIONS: These results suggest that the platelet lipoxygenase pathway is activated in aspirin-intolerant patients and that the production of oxygen-free radicals may differentiate aspirin-tolerant from aspirin-intolerant asthmatic subjects. Our study, however, does not support the hypothesis that an increase in lipoxygenase products may be responsible for oxygen-free radical production. Moreover, a lowered platelet GSH-Px activity does not seem to be involved in this phenomenon.

Adult↗
PubMed1994

Immune-inflammatory functions of fibroblasts.

Inflammation is a response that has evolved over millions of years to become an extremely complex process. This complexity reflects the host's need to deal effectively with a wide variety of potentially injurious agents, as well as the need to incorporate an adequate set of checks and balances. An inappropriately checked response, which occurs rarely, results in disease, either acute or chronic. However, in most instances, inflammation is a beneficial response, essential for survival. Inflammation comprises an extensive network of cellular interactions implemented by an overwhelming number of molecules. One category of signal includes soluble products, such as neuropeptide, lipid mediators, cytokines and growth factors, most of which can be produced by inflammatory/haemopoietic cells. However, resident structural cells can also produce many of these products and, on this basis only, fibroblasts, epithelial, endothelial and smooth muscle cells should be considered as active contributors to the regulation of the inflammatory response. Extracellular matrix (ECM) proteins comprise another category of signals. Whilst the most recognized activities of these proteins are those concerned with providing structural tissue integrity, it is clear that they also have powerful inductive effects. Indeed, ECM proteins can influence the shape, movement and state of activation of inflammatory cells in the tissue. Recent evidence indicates that these signals may also play substantial roles in homing of inflammatory cells to certain sites and in the handling of a number of cytokines and growth factors. In so far as fibroblasts are the main producers of ECM proteins, these new data establish an indirect but important role for fibroblasts in the regulation of the inflammatory response.

Animals↗
PubMed1993

Altered leukotriene B4 levels by HL-60 cells after monocytic/macrophage differentiation.

The differentiation of HL-60 human promyelocytic leukaemia cells into specific monocytic or granulocytic lineage cells depending of the inductor agent is accompanied by selective regulation of several key enzymes involved in the synthesis of eicosanoids. In this communication we have investigated the changes in arachidonic acid metabolic profiles during phorbol 12-myristate 13-acetate (PMA)-induced monocytic differentiation of HL-60 cells. Our results show that HL-60 cells have spontaneous capacity to synthesize large amounts of LTB4, but PMA-differentiated cells lose the ability to release LTB4. Significant differences are found between HL-60 cells and PMA-treated cells in basal conditions and under ionophore stimulation. The addition of LTB4 at the time of PMA differentiation did not have effects on cell proliferation, but nordihydroguaiaretic acid (NDGA), a potent 5-lipoxygenase inhibitor, also inhibited HL-60 cell proliferation and did not have any effect on PMA-differentiated cell proliferation.

Arachidonic Acids↗
PubMed1993

Release of chemical mediators and inflammatory cell influx during early allergic reaction in the nose: effect of furosemide.

BACKGROUND: We evaluated the effect of furosemide on allergen-induced rhinitis in a double-blind, crossover, placebo-controlled experiment. METHODS: Fourteen patients with rhinitis who were allergic to house dust were nebulized with an intranasal dose of 20 mg of furosemide or placebo before allergen challenge with an extract of Dermatophagoides pteronyssinus (100 BU). Clinical evaluation and nasal lavages with normal saline solution were performed at baseline; after placebo-furosemide nebulization, and at 10, 30, and 60 minutes after allergen challenge. Number of sneezes and a composite symptom score were recorded to evaluate clinical response. Prostaglandin E2 (PGE2), PGD2 peptide leukotrienes and 15-hydroxy, 5,8,11,13-eicosatetraenoic acid (15-HETE) were measured by radioimmunoassay in nasal lavages. Cells were counted and classified as epithelial cells, neutrophils, eosinophils, and others. RESULTS: No differences in either clinical symptoms or cell influx after allergen challenge were found between furosemide and placebo groups. PGE2 levels did not change after provocation, and furosemide had no effect on its production. Ten minutes after antigen challenge there was a marked increase of PGD2 (p < 0.01), peptide leukotrienes (p < 0.01), and 15-HETE (not significant) on both study days. However, no significant differences in the release of eicosanoids were found between furosemide and placebo groups. CONCLUSIONS: Our observations in the nasal mucosa suggest that furosemide has no effect on the release of proinflammatory and bronchoconstrictor metabolites (PGD2, peptide leukotrienes, and 15-HETE). In contrast to bronchial asthma, allergen-induced rhinitis was not effectively prevented by furosemide.

Adult↗
PubMed1993

Markers of early renal changes induced by industrial pollutants. II. Application to workers exposed to lead.

The present study has been carried out in the framework of a collaborative research project on the development of new markers of nephrotoxicity. A battery of more than 20 potential indicators of renal changes has been applied to 50 workers exposed to lead (Pb) and 50 control subjects. After application of selection criteria 41 exposed and 41 control workers were eventually retained for the final statistical analysis. The average blood Pb concentration of exposed workers was 480 micrograms/l and their mean duration of exposure was 14 years. The battery of tests included parameters capable of detecting functional deficits (for example, urinary proteins of low or high molecular weight), biochemical alterations (for example, urinary eicosanoids, glycosaminoglycans, sialic acid) or cell damage (for example, urinary tubular antigens or enzymes) at different sites of the nephron or the kidney. The most outstanding effect found in workers exposed to Pb was an interference with the renal synthesis of eicosanoids, resulting in lower urinary excretion of 6-keto-PGF1 alpha and an enhanced excretion of thromboxane (TXB2). The health significance of these biochemical alterations, detectable at low exposure to Pb is unknown. As they were not associated with any sign of renal dysfunction, they may represent reversible biochemical effects or only contribute to the degradation of the renal function from the onset of clinical Pb nephropathy. The urinary excretion of some tubular antigens was also positively associated with duration of exposure to Pb. Another effect of Pb that might deserve further study is a significant increase in urinary sialic acid concentration.

Adult↗
PubMed1993

Markers of early renal changes induced by industrial pollutants. III. Application to workers exposed to cadmium.

Cadmium (Cd) was the third heavy metal investigated in the European collaborative research project on the development and validation of new markers of nephrotoxicity. Fifty workers exposed to Cd and 50 control workers were examined. After application of selection criteria 37 workers (mean age 43) exposed to Cd for an average of 11.3 years; and 43 age matched referents were retained for final analysis. The average concentrations of Cd in blood (Cd-B) and urine (Cd-U) of exposed workers were 5.5 micrograms Cd/l and 5.4 micrograms Cd/g creatinine respectively. By contrast with lead and mercury, Cd had a broad spectrum of effects on the kidney, producing significant alterations in amounts of almost all potential indicators of nephrotoxicity that were measured in urine--namely, low and high molecular weight proteins, kidney derived antigens or enzymes, prostanoids, and various other biochemical indices such as glycosaminoglycans and sialic acid. An increase in beta 2-microglobulin and a decrease of sialic acid concentration were found in serum. Dose-effect/response relations could be established between most of these markers and Cd-U or Cd-B. The thresholds of Cd-U associated with a significantly higher probability of change in these indicators were estimated by logistic regression analysis. Three main groups of thresholds could be identified: one around 2 micrograms Cd/g creatinine mainly associated with biochemical alterations, a second around 4 micrograms Cd/g creatinine for high molecular weight proteins and some tubular antigens or enzymes, and a third one around 10 micrograms Cd/g creatinine for low molecular weight proteins and other indicators. The recent recommendation by the American Conference of Governmental Industrial Hygienists (ACGIH) of 5 micrograms Cd/g creatinine in urine as the biological exposure limit for occupational exposure to Cd appears thus justified, although for most of the effects occurring around this threshold the link with the subsequent development of overt Cd nephropathy is not established. In that respect, the very early interference with production of some prostanoids (threshold 2 micrograms Cd/g creatinine) deserves further investigation; although this effect might contribute to protect the filtration capacity of the kidneys, it might also play a part in the toxicity of Cd on bone.

Adult↗
PubMed1993

Failure of frusemide to increase production of prostaglandin E2 in human nasal mucosa in vivo.

BACKGROUND: It has been suggested that inhaled frusemide protects subjects with asthma against bronchoconstriction by enhancing the synthesis of prostaglandin E2 (PGE2). To evaluate this hypothesis the effect of frusemide on PGE2 production from nasal mucosa was studied. METHODS: Two main arachidonic acid metabolites produced by epithelial cells, PGE2 and 15-hydroxy 5,8,11,13-eicosatetraenoic acid (15-HETE), were measured by radioimmunoassay in nasal secretions obtained by nasal lavages with saline. Eleven healthy volunteers were randomly assigned to two study days, one week apart, in a double blind crossover study. Nasal instillation with three increasing doses of frusemide (5, 10, and 20 mg) or placebo was carried out at intervals of 15 minutes. Nasal lavages were performed immediately before nasal instillations and 15, 30, and 60 minutes after the last instillation. RESULTS: Baseline concentrations of 15-HETE were at least six times higher than PGE2. No differences between frusemide and placebo were detected either on PGE2 or 15-HETE release. CONCLUSIONS: The findings do not support the hypothesis that the antiasthmatic effect of frusemide may be due to increased synthesis of PGE2 or release in the respiratory mucosa.

Adult↗
PubMed1992

Solid-phase extraction of prostanoids using an automatic sample preparation system.

A commercial automated solid-phase extraction system for cyclooxygenase arachidonic acid metabolites in urine samples has been evaluated. Comparison of manual and automatic batch (36 samples) extraction procedures for tritium labelled prostanoids added as tracers to urine samples has shown equivalent results with recoveries greater than 90% for prostaglandins E2, F2alpha and 6-keto prostaglandin F1alpha as well as thromboxane B2. Analyte stability is not affected by the automated procedure, which uses less solvents and has a faster overall processing time than the manual method. The automated system has been applied to the extraction of prostanoids in urine samples from workers exposed to dichloroethane.

Arachidonic Acids↗
PubMed1992

In vivo transformation of arachidonic acid into 12-hydroxy-5,8,10,14-eicosatetraenoic acid by human nasal mucosa.

A method for the determination of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) by gas chromatography-mass spectrometry (GC-MS) in samples obtained from healthy subjects by nasal lavage is presented. HETEs were extracted from samples obtained by nasal lavage using C18 solid-phase cartridges. The purification of 12-HETE and 5-HETE was carried out in two consecutive steps of purification by reversed-phase high-performance liquid chromatography. Methylated and trimethylsilylated fractions were separated by GC-MS with electron-impact ionization. The production of 12-HETE by human nasal mucosa was confirmed by GC-MS.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1992

Human and experimental studies on renal eicosanoid response to long-term cadmium exposure.

In order to assess the effects of long-term exposure to cadmium (Cd) on the renal metabolism of eicosanoids, the urinary excretion of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), and thromboxane B2 (TXB2) was determined in 37 workers exposed to Cd and in female Sprague-Dawley rats given 100 ppm Cd in drinking water for 10 months. Urinary output of sodium and calcium was also determined. The Cd-exposed workers showed an increased urinary concentration of 6-keto-PGF1 alpha, PGE2, sodium, and calcium. The rise of 6-keto-PGF1 alpha was related to Cd levels in blood and weakly correlated with urinary sodium. Calcium in urine was not related to the concentration of the metal in blood and urine. A slight elevation in urinary TXB2 was also observed in workers with blood Cd higher than 5 micrograms/liter. After 10 months of exposure to Cd, female Sprague-Dawley rats presented an enhanced urinary excretion of albumin, transferrin, beta 2-microglobulin, sodium, and PGE2 in urine. The latter was significantly correlated with albuminuria and transferrinuria. In conclusion the results show that chronic exposure to Cd induces changes in the urinary excretion of some eicosanoids. The possible relation of these changes to Cd-induced kidney dysfunction are discussed.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Oxidative metabolism of N-phenyllinoleamide by human nasal polyps.

N-phenyllinoleamide (NPLA), the anilide of linoleic acid, has been associated with the epidemiology of Toxic Oil Syndrome, but no data are available on its metabolism. On account of the similarity in chemical structure between the linoleic acid and NPLA, the aim of this study has been to investigate the oxidative metabolism of this xenobiotic by the human nasal polyp, a tissue with elevated 15-lipoxygenase activity. For this purpose, tissue homogenates have been incubated for 2 h with NPLA (0.1 mM) spiked with either N-(ring G-3H)PLA (0.2 microCi/ml) or N-P(1-14C)LA (0.05 microCi/ml). Gas chromatographic/mass spectrometric analysis of the high performance liquid radiochromatographic fractions shows that the 9,12,13-trihydroxy, 12,13-epoxy-11-hydroxy and 13-hydroxy NPLA derivatives are the major metabolites. These results revealed that NPLA metabolites are chemical structures related to the linoleic acid derivatives, some of which may show biological activity.

Anilides↗
PubMed1992

Release of peptide leukotriene into nasal secretions after local instillation of aspirin in aspirin-sensitive asthmatic patients.

Although the mechanism of aspirin-induced asthma and rhinitis is unknown, it has been suggested that adverse nasal and bronchial reactions are caused by an increased production of lipoxygenase products. In examining this hypothesis we have measured the release of peptide leukotrienes (PeptLTs), 15-HETE, and prostaglandins in nasal fluids obtained by nasal lavages after instillation of acetylsalycilic acid (ASA) and placebo (saline). Ten ASA-sensitive asthmatics, 10 ASA-insensitive asthmatics, and seven healthy subjects were challenged in a double-blind study with normal saline and 12 mg of ASA. Twelve mg were administered based on the results of a previous study that showed that this dose caused minor to moderate symptoms in ASA-sensitive patients. PeptLTs, LTB4, 15-HETE, PGE2, PGF2 alpha, and PGD2 were measured by radioimmunoassay methods. Significant levels of PeptLTs were detected in sensitive asthmatic patients 60 min after nasal challenge. This change was associated with a significant increase in symptoms. No increase in PeptLTs levels were found, however, in either insensitive patients or healthy subjects. Inhibition of PGE2 and PGF2 alpha release was detected in the three groups after ASA administration. ASA also inhibited PGD2 release in insensitive asthmatic patients but not in both sensitive patients and healthy subjects. These results suggest that an abnormal release of PeptLTs in ASA-sensitive asthmatic patients contributes to nasal and bronchial adverse reactions. The lack of effects on PGD2 release suggests that mast cells from ASA-insensitive patients are more sensitive to ASA than those from sensitive asthmatic patients and healthy subjects.

Administration, Intranasal↗