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Biomedical subjects

D Girard

Publications and source records attributed to D Girard.

At least 19 recordsLinked to original sources
PubMed1996

Effects of interleukin-13 on human neutrophil functions.

It was recently shown that interleukin-13 (IL-13) induces the expression and release of the IL-1 decoy receptor (type II) in human neutrophils along with the production of the IL-1 receptor antagonist. In the present study we focused on further studying the modulatory effects of IL-13 on these cells. We found that recombinant human IL-13 (rhIL-13) induces cellular morphological changes in neutrophils that are typical of activated cells. Furthermore, rhIL-13 was shown to increase tyrosine phosphorylation of several neutrophil proteins. We also demonstrate that this cytokine stimulates de novo RNA synthesis in a concentration-dependent fashion as measured by [5-3H]uridine incorporation and that rhIL-13 induces the synthesis of several neutrophil proteins according to high-resolution two-dimensional gel electrophoresis of metabolically [35S]-labeled cells. We observed that the IL-8 levels in the external milieu of IL-13-stimulated cells was almost fivefold increased when compared with control cells. Finally, we observed that rhIL-13 has no significant effect on phagocytosis and apoptosis. Taken together, our results demonstrate that IL-13 is a modulator of several human neutrophil functions. This leads us to conclude that the modulatory role of IL-13 on human neutrophils, a potentially important anti-inflammatory cytokine, is more complex than previously believed. Furthermore, because we show that the synthesis of several as yet unidentified proteins was up-regulated by IL-13, our findings open new avenues of research on the effects of this cytokine on human neutrophils.

Apoptosis↗
PubMed1996

Detection of gas embolism by transesophageal echocardiography during laparoscopic cholecystectomy.

Using transesophageal echocardiography (TEE), 16 patients (ASA physical status I-III), undergoing laparoscopic cholecystectomy, were assessed for the occurrence of episodes of gas embolism and cardiovascular changes related to those emboli. The long-axis four-chamber view was monitored continuously, except for predetermined intervals where the transgastric short-axis view was obtained to derive the end-diastolic area (EDA), the end-systolic area (ESA), and the ejection fraction (EF). In one patient, we monitored the longitudinal view of the superior and the inferior vena cava. The monitoring of the patients also included: heart rate (HR), mean arterial pressure (MAP), arterial saturation by pulse oximetry (Spo2), end-tidal CO2 (ETCO2), minute ventilation (VE), and peak inspiratory pressure (PIP). Embolic events were defined as the appearance of gas bubbles in the right cardiac chambers. We observed gas embolism in 11/16 patients (five during peritoneal insufflation and six during gallbladder dissection). Using the longitudinal view of the superior and inferior vena cava (IVC), we found that these emboli were transmitted through the IVC. No episode of cardiorespiratory instability (decrease in MAP > or = 10 mm Hg, Spo2 < 90%) was observed. There was no significant difference in cardiorespiratory variables between patients who presented gas embolism (n = 11) and patients who did not (n = 5) during the studied period. In this small group of patients, we conclude that gas embolism occurs commonly during laparoscopic cholecystectomy but that these gas emboli cause minimal cardiorespiratory instability.

Adult↗
PubMed1996

Phototoxicity of some bromine-substituted rhodamine dyes: synthesis, photophysical properties and application as photosensitizers.

The synthesis of some bromine-substituted rhodamine derivatives viz., 4,5-dibromorhodamine methyl ester (dye 2) and 4,5-dibromorhodamine n-butyl ester (dye 3) are reported. These dyes were synthesized to promote a more efficient cancer cell photosensitizer for potential use in in vitro bone marrow purging in preparation for autologous bone marrow transplantation. Spectroscopic and photophysical characterization of these dyes together with rhodamine 123 (dye 1) are reported in water, methanol, ethanol and also in a microheterogeneous system, sodium dodecyl sulfate. The possible mechanism of photosensitization is characterized in terms of singlet oxygen efficiency of these dyes. Singlet oxygen quantum yields for bromine-substituted dyes are in the range of 0.3-0.5 depending on the solvent. For dye 1 no singlet oxygen production is found. The photodynamic actions of these dyes in different cell lines are tested. It was found that dye 2 and dye 3 are efficient photosensitizers and mediate eradication of K562, EM2, myeloid cell lines (CML) and the SMF-AI rhabdomyosarcoma line.

Animals↗
PubMed1995

Effects of interleukin-2 on gene expression in human neutrophils.

Recently, the interleukin-2 receptor (IL-2R) was shown to be present on human neutrophils, and IL-2-neutrophil interactions are believed to be important in both tumor rejection and increased susceptibility to bacterial infections. Furthermore, neutrophils have been shown to synthesize host defense proteins, such as cytokines. In this study, we analyzed the effects of IL-2 on the induction of de novo RNA and protein synthesis in this cell type. When cells were stimulated with IL-2 alone, the level of incorporation of either [5-3H]-uridine or [35S]-methionine and [35S]-cysteine was similar to unstimulated cells. However, when cells were stimulated with the combination of a fixed concentration of granulocyte-macrophage colony-stimulating factor (GM-CSF), a dose-dependent effect of IL-2 was observed on the induction of both RNA and protein synthesis. In the presence of tumor necrosis factor-alpha or formyl-methionyl-leucyl-phenylalanine, however, IL-2 exerted no similar effect. Furthermore, the study of a large number of normal subjects (n = 55) showed reproducible categories of responders (low, intermediate, and high). The binding of IL-2 to the IL-2R complex on human neutrophils increased on GM-CSF-stimulated neutrophils compared with unstimulated cells. However, no increase in the level of expression of either the alpha or beta chains of this receptor complex was observed. This finding suggests that GM-CSF functionally activates the IL-2R, but does not regulate its level of expression. Finally, we found that human neutrophils constitutively express IL-2R gamma chain mRNA and thus have the potential to express the functional IL-2R complex. Our findings on IL-2-neutrophil interactions should lead to new avenues of research in understanding the responses of patients undergoing GM-CSF or IL-2 therapy.

Base Sequence↗
PubMed1995

Immunotoxicity of aminocarb. III. Exposure route-dependent immunomodulation by aminocarb in mice.

Aminocarb, a phenylsubstituted methylcarbamate pesticide (4-dimethylamino-3-methyl-N-carbamate; matacil), previously suspected of a relatively low immunotoxic potential, was administered by four different exposure routes to C57BL/6 mice. A single sublethal exposure by oral and dermal routes stimulated humoral immune response at a relatively low dose; 1/256 LD50 of aminocarb. Intraperitoneal (i.p.) injection decreased the humoral PFC response, whereas inhalation of aminocarb had no marked effect on peripheral immune status in exposed animals. Thus, i.p. exposure resulted in higher immunotoxicity over oral administration of aminocarb. Similarly, marked route-related exposure differences in immunomodulatory effects of aminocarb were noted for mitogenic stimulation of spleen lymphocytes and mixed lymphocyte response. Other indices, such as delayed type hypersensitivity (DTH) and production of interleukin-2 (IL-2) were unchanged. Interestingly, expression of major histocompatibility complex (MHC) class II by purified, lipopolysaccharide (LPS)-stimulated B cells increased equally after i.p. and oral exposures to aminocarb. Overall, a weak immunosuppressive potential of aminocarb was concluded, which was possibly due to indirect interaction of the pesticide with the immune system. However, aminocarb may represent an autoimmunity-inducing toxic.

Administration, Cutaneous↗
PubMed1995

Anti-microfilament IgG antibodies in normal adults and in patients with autoimmune diseases: immunofluorescence and immunoblotting analysis of 201 subjects reveals polyreactivity with microfilament-associated proteins.

We have investigated IgG antibodies to microfilament-associated proteins in sera from 29 normal controls and from 172 patients with autoimmune diseases such as rheumatoid arthritis (n = 45), systemic lupus erythematosus (n = 43), polymyositis/dermatomyositis (n = 36), systemic sclerosis (n = 35), and autoimmune chronic active hepatitis (CAH, n = 13). We observed, by indirect immunofluorescence, a staining pattern in which the fluorescence was continuously distributed along microfilaments by using several animal and human cell lines as substrate. Because no reactivity with individual bands or specific combinations of bands was observed by immunoblotting using different cell lines, we further characterized our sera by immunoblotting using a panel of the purified microfilament-associated proteins filamin, myosin, alpha-actinin, actin, tropomyosin, and myosin light chain. Results shows that normal as well as autoimmune sera are polyreactive with microfilament proteins. The specificity of reactivity against a particular microfilament-associated protein was demonstrated by inhibition experiments with the specific protein. No correlation was observed between immunoblot and immunofluorescence results. Of the 201 sera, 40 (20%), 42 (21%), 31 (15%), 26 (13%), 34 (17%), 24 (12%), 4 (2%), and 0 (0%) reacted, respectively, by immunoblotting with 0, 1, 2, 3, 4, 5, 6, or 7 of the microfilament-associated proteins. Furthermore, 57 different profiles of reactivity with the panel proteins were observed. All autoimmune CAH sera reacted with at least 3 proteins. This result was strikingly unique to this group. Anti-actin antibodies were as common in normal as in CAH sera. Anti-alpha-actinin antibodies were strikingly more frequent in CAH than in any group. We conclude that a remarkable diversity of anti-microfilament antibodies is present in normal as well as in autoimmune sera and that a continuous microfilament fluorescent pattern is not restricted simply to anti-actin antibodies. Furthermore, sera negative by immunofluorescence react with several miocrofilament-associated proteins by immunoblotting. Reactivity with multiple (> or = 3) microfilament-associated proteins including alpha-actinin distinguishes CAH sera from normal and other autoimmune sera.

Actin Cytoskeleton↗
PubMed1995

Characterization of a novel human antibody xenoreactive with fibronectin.

Recent reports have used bovine fibronectin (Fn) as source of antigen to study human anti-Fn autoantibodies. We have characterized a novel human antibody (Ab) reactive with bovine and marsupial Fn, but not with human Fn. Indirect immunofluorescence, wet cleaving and protein adherence assays, immunoblotting, blot-affinity purification, a cell adhesion inhibition assay, and competitive experiments with synthetic peptides were used to characterize the anti-Fn Ab in serum from a patient with an undifferentiated connective tissue disease. A characteristic Fn-like network was observed by indirect immunofluorescence on bovine MDBK and marsupial PtK2 cells, but not on various human cell lines. Double immunofluorescence revealed colocalization of the Ab with a mouse monoclonal anti-Fn Ab. A reactive polypeptide of 240 kDa corresponding to the M(r) of Fn was identified by immunoblotting using MDBK and PtK2 total cell lysates. The Ab reacted with the 240-kDa band of purified bovine Fn with an endpoint titer of 1:64,000, while no reactivity was observed with human cellular or plasma Fn. Blot-affinity purification of the Ab from the 240-kDa PtK2 region confirmed that the Fn-like fluorescent pattern observed was due to reactivity with the 240-kDa band and not with other regions of the blot. The Ab affinity-purified from the 240-kDa region also reacted with purified bovine Fn by immunoblotting. Functional analysis disclosed specific inhibition of PtK2 and MDBK cell adhesion by the affinity-purified anti-Fn Ab. Competitive experiments with synthetic peptides demonstrated that the epitope is located in the decapeptide RGDSPASSKP containing the cell-binding domain of Fn. Longitudinal analysis of the Ab revealed its persistence over 6 years. Bovine and marsupial Fn can be the focus of a highly specific and persistent human immune response. Reactivity of a human Ab with bovine Fn does not imply cross-reactivity with human Fn. In light of recent reports using bovine Fn to characterize human anti-Fn "autoantibodies," future studies on human anti-Fn should specifically employ purified human Fn as antigen.

Adult↗
PubMed1995

Separation of overlapping spectra from evolving systems using factor analysis. 3. Fluorescence spectra of hematoporphyrin IX di-n-propylether diethanolamide.

Fluorescence spectroscopy of hematoporphyrin IX di-n-propylether diethanolamide (HPPEEA) in aqueous solutions, with and without SDS, was obtained in the pH range from 0.1 to 13. At pH greater than 3, HPPEEA in water solutions gives spectra complicated by aggregation whereas in aqueous SDS solutions, the aggregation is greatly reduced. Factor analysis is used to separate the spectra of the individual species from the experimental spectra. Five and four species are identified in pure water and in aqueous SDS solutions, respectively. The predominant species are: two free bases at pH higher than 6; one monocation at pH near 4; and two or one dications at pH lower than 2.5. The intensity signatures are related to the ionic distribution and to the aggregation situation of HPPEEA at different pH.

Amphotericin B↗
PubMed1995

Separation of overlapping spectra from evolving systems using factor analysis. 4. Fluorescence spectra of hematoporphyrin IX.

Fluorescence spectra of hematoporphyrin IX (Hp) in water and in aqueous SDS solutions are obtained in the pH range 0.1 to 13 to determine the ionisation state of the molecule as a function of pH. In water, the spectra are complicated by aggregation which is quite severe near pH 4. In aqueous SDS, the aggregation is much less violent. Factor analysis (FA) is used to identify five species in the fluorescence spectra in each series of solutions. The distribution curve of these species as a function of pH is also obtained. By comparing the spectra and the distribution curve of Hp with those of HPPEEA, an ethanolamide derivative of Hp that does not contain the carboxylic groups (Part 3), the species are identified. For Hp in water we have obtained the following species: the dication in two allotropic forms in the pH range 0 to 5; the monocation (with the charge on an imino nitrogen) in the pH range 2 to 7; and the free base in the pH range 3.5 to 13. The monocation observed by the second derivative technique revealed three subspecies. For Hp in aqueous SDS we have obtained the following species; one dication in the pH range 0 to near 4; one monocation (with the charge on an imino nitrogen) in the pH range 0.5 to 9; three free bases (with no charge on the imino nitrogen) in the pH range 4 to 13. Of the latter, one species is the neutral molecule, another is a dianion (with the charges on the carboxylic side chains), and the third one appearing at pH higher than 10 is an allotropic form of the dianion.

Factor Analysis, Statistical↗
PubMed1995

In vivo efficacy of trovafloxacin (CP-99,219), a new quinolone with extended activities against gram-positive pathogens, Streptococcus pneumoniae, and Bacteroides fragilis.

The interesting in vitro antimicrobial activity and pharmacokinetics of the new quinolone trovafloxacin (CP-99,219) warranted further studies to determine its in vivo efficacy in models of infectious disease. The significance of the pharmacokinetic and in vitro antimicrobial profiles of trovafloxacin was shown through efficacy in a series of animal infection models by employing primarily oral therapy. Against acute infections, trovafloxacin was consistently more effective than temafloxacin, ciprofloxacin, and ofloxacin against Streptococcus pneumoniae and other gram-positive pathogens while maintaining activity comparable to that of ciprofloxacin against gram-negative organisms. In a model of murine pneumonia, trovafloxacin was more efficacious than temafloxacin, while ciprofloxacin failed against S. pneumoniae (50% protective doses, 2.1, 29.5, and >100 mg/kg, respectively). In addition to its inherent in vitro potency advantage against S. pneumoniae, these data were supported by a pharmacokinetic study that showed levels of trovafloxacin in pulmonary tissue of S. pneumoniae-infected CF1 mice to be considerably greater than those of temafloxacin and ciprofloxacin (twice the maximum drug concentration in serum; two to three times the half-life, and three to six times the area under the concentration-time curve). Against localized mixed anaerobic infections, trovafloxacin was the only agent to effectively reduce the numbers of recoverable CFU of Bacteroides fragilis ( >1,000-fold), Staphylococcus aureus (1,000-fold), and Escherichia coli ( >100-fold) compared with ciprofloxacin, vancomycin, metronidazole, clindamycin, cefoxitin, and ceftriaxone. The in vitro and in vivo antimicrobial activities of trovafloxacin and its pharmacokinetics in laboratory animals provide support for the ongoing and planned human phase II and III clinical trials.

Animals↗
PubMed1995

Cross-sectional assessment of workers with repeated exposure to chlorine over a three year period.

Airflow obstruction has been described in workers who experienced symptoms after acute exposure to chlorine. Persistent bronchial hyperresponsiveness has also been assessed, but mainly in case studies. In this cross-sectional study, we have assessed the relationship between inhalational accidents ("puffs") involving chlorine and persistent symptoms as well as hyperresponsiveness in 239 out of 255 at-risk workers (94%). No relationship was found between persistent symptoms and the exposure variables studied. Forced vital capacity (FVC) was higher in subjects who had had no symptoms after a "puff", compared with those who had experienced mild symptoms. Forced expiratory volume in one second (FEV1) and FVC were significantly lower in subjects who experienced more than 10 puffs with mild symptoms than in subjects who reported no symptomatic puff. The presence of bronchial hyperresponsiveness was not related to exposure, but the methacholine dose-response slope showed a tendency to increased bronchial responsiveness with increased exposure. A significant difference was shown in subjects who experienced more than 10 puffs with mild symptoms. In this group of workers, repeated exposure to chlorine with acute respiratory symptoms was associated with a slight but significant reduction in expiratory flow rates, together with an increase in bronchial responsiveness, without long-term symptoms.

Adolescent↗
PubMed1995

Characterization of a novel human IgG antibody reactive with a Ca(2+)-sensitive cell-cell adhesion epitope of PtK2 epithelial cells.

We have characterized a human IgG antibody present in the serum of a patient with an autoimmune undifferentiated connective tissue disease and reactive with PtK2 epithelial cell-cell adhesions. The fluorescent staining pattern is observed only at cell-cell contacts whether cells are permeabilized or not. The serum reacts with polypeptides of 90, 48 and 45 kD by immunoblotting. IgG affinity-purified from these bands failed to reproduce the original immunofluorescence staining pattern. Treatment with cycloheximide did not abolish the staining pattern suggesting that the recognized antigen is not a newly expressed protein. However, when EGTA was used for chelating calcium ions in the culture medium the original staining pattern observed at cell-cell adhesions was affected although some fluorescence was still present at cell periphery. This was reversible when cells were reincubated with fresh medium containing Ca2+. The recognized antigen colocalizes at cell-cell adhesions with actin, the microfilament-associated proteins vinculin, alpha-actinin and myosin light chain, and with Triton-insoluble uvomorulin (E-cadherin) material. We conclude that the antibody reacts with, at least, an extracellular portion of a Ca(2+)-dependent PtK2 antigen. The characterization of this antibody based on (1) its localization at cell-cell adhesions, (2) its sensitivity to EGTA-treatment and (3) its colocalization with the epithelial cellular adhesion molecule (CAM) uvomorulin, strongly suggest that the recognized Ag is a CAM or a CAM-associated protein.

Autoimmune Diseases↗
PubMed1994

[Prevalence of antimitochondrial antibodies in women with Hashimoto's thyroiditis].

OBJECTIVES: Thyroid antibodies are present in more than 15% of patients with primary biliary cirrhosis. Inversely, the prevalence of antimitochondrial antibodies in patients with thyroid antibodies is still unknown. The aim of the present study was to evaluate the prevalence of antimitochondrial antibodies in women positive for thyroid microsomal antibodies. METHODS: Anti-thyroid microsomal positive sera were collected from 351 selected female patients (age range 40-70 years) then stored at -20 degrees C from September 91 to September 92. Anti-mitochondrial auto-antibodies were determined in all sera with enzyme-linked sorbent assay (ELISA) using purified antigen. RESULTS: M2 antimitochondrial antibodies were found positive in 7 cases (2%). On immunoblots, the pattern of antimitochondrial reactivity visualized for the 7 sera was similar to pattern of classical primary biliary cirrhosis sera. Six of the 7 patients were asymptomatic and 4 had normal liver function tests. Liver biopsy was carried out in 2 patients and fulfilled diagnosis criteria for primary biliary cirrhosis. Six out of the 7 patients had Hashimoto's thyroiditis (2 biopsy proven, 4 clinical and biological diagnosis). CONCLUSION: Patients with Hashimoto's thyroiditis would be a population at high risk of primary biliary cirrhosis. It would be interesting to screen these patients in order to ascertain the signification of antimitochondrial antibody positivity, especially when there is no apparent liver disease.

Adult↗
PubMed1994

Antithrombotic actions of argatroban in rat models of venous, 'mixed' and arterial thrombosis, and its effects on the tail transection bleeding time.

1. The antithrombotic action of argatroban, a synthetic thrombin inhibitor, was studied in three models of thrombosis in the rat, and in the tail transection bleeding time test. Heparin was studied as a reference anticoagulant. 2. In the model of venous thrombosis induced by thromboplastin followed by stasis of the abdominal vena cava, argatroban had an ED50 of 125 micrograms kg-1, when administered as an i.v. bolus 5 min prior to the thromboplastin injection: the ED50 of heparin was 42 micrograms kg-1, where ED50 is the dose which reduces the weight of the thrombus by 50% compared with that of the control animals. When the two compounds were administered by continuous i.v. infusion, argatroban (ED50 = 1.5 micrograms kg-1 min-1) had the same potency as heparin (ED50 = 1.2 micrograms kg-1 min-1). 3. Argatroban was active in the arterio-venous shunt model with an ED50 of 0.6 mg kg-1 when the compound was given as a bolus. The ED50 of heparin was 0.04 mg kg-1 under the same conditions. The two compounds had ED50 values of 6 micrograms kg-1 min-1 (argatroban) and 3 micrograms kg-1 min-1 (heparin), when administered by continuous i.v. infusion. 4. When tested against occlusive arterial thrombus formation by electrical stimulation of the left carotid artery, both compounds given as either an i.v. bolus or a continuous infusion led to dose-dependent increases in the duration of post-lesion vessel patency. Heparin bolus was more active than argatroban on a weight basis, in that 2 mg kg-1 gave a similar increase in the time to occlusion as 8 mg kg-1 argatroban. As in the other models, when given as continuous infusions, argatroban (111% increase in time to occlusion at 20 tg kg-1, min-1) had similar activity to that of heparin (180% increase at 25 jg kg-1 min-1) on a weight basis. Hoever, the antithrombotic effects of argatroban were accompanied by only moderate changes in the coagulation parameters (thrombin time and activated partial thromboplastin time, APTT), whereas, even at a subthreshold dose of heparin (12.5 pg kg-1 min-1), both the thrombin time and the APTT were greater than 150 s.5. Infusions of both compounds caused dose-dependent increases in the tail transection bleeding time,with the dose of argatroban that doubles the bleeding time (11 I g kg-1 min-1) being five times greater than that of heparin (EDI, = 2.2 fig kg-1 min-1).6. These data show that, when administered as an intravenous infusion, argatroban is a potent antithrombotic agent in rat models of venous 'mixed' and arterial thrombosis, this effect can be obtained with a lower degree of systemic anticoagulation than with heparin in the arterial model, and argatroban has a lower haemorrhagic potential than that of heparin.

Animals↗
PubMed1994

Venous carbon dioxide embolism in pigs: an evaluation of end-tidal carbon dioxide, transesophageal echocardiography, pulmonary artery pressure, and precordial auscultation as monitoring modalities.

We evaluated the effects of CO2 embolism on end-tidal carbon dioxide (ETCO2) and compared four methods for detection of gas embolism. Fourteen pigs were monitored for CO2 embolism with transesophageal echocardiography (TEE), changes in ETCO2, changes in mean pulmonary artery pressure (MPAP), and precordial auscultation (AUSC). Serial injections of CO2 (ranging from 0.05 to 5.0 mL/kg) were performed in seven pigs (Group 1). In the other seven pigs, CO2 was infused at rates between 0.01 and 0.4 mL.kg-1.min-1 (Group 2). Positive responses were defined as an acute change in heart sounds (AUSC), visualization of gas bubbles in the right cardiac chambers on TEE, an increase in MPAP > or = 3 mm Hg, and an acute change (increase or decrease) in ETCO2 > or = 3 mm Hg. In both groups, positive responses to CO2 embolism were represented by an initial decrease in ETCO2. The frequency with which positive responses were observed revealed that TEE was the most sensitive method (P < 0.05), whereas no differences were found among the other methods. In conclusion, in this model, positive response to CO2 embolism was represented by a decrease in ETCO2. TEE was the most sensitive method of detection of CO2 embolism, and ETCO2, MPAP, and AUSC were equally sensitive.

Animals↗