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Biomedical subjects

A Bernard

Publications and source records attributed to A Bernard.

At least 289 records · Page 16Linked to original sources
PubMed1994

Antibiotic prophylaxis in pulmonary surgery. A prospective randomized double-blind trial of flash cefuroxime versus forty-eight-hour cefuroxime.

The aim of this study was to determine whether a 48-hour antibiotic prophylaxis regimen with a second-generation cephalosporin was more efficient than a flash antibiotic prophylaxis regimen in pulmonary operations. All the included patients underwent lung resection. Patients with preoperative infection were excluded. All the patients were given cefuroxime (1.5 gm intravenously) at the time of the anesthetic induction and again 2 hours later. The randomization was done postoperatively: group 1 was given placebo intravenously (n = 102) and group 2 was given cefuroxime intravenously (n = 101), each every 6 hours for 48 hours. The overall rate of infections was 46% in the 48-hour cefuroxime group versus 65% in the flash group (p = 0.005). The difference remained significant even after an adjustment with prognosis variables (p = 0.01). Six empyemas (6%) in the flash group were noted versus one (1%) in the 48-hour group (p = 0.03). From day 3 to day 8 after the operation, chest x-rays films were more often assessed as being normal in the flash group than in the 48-hour group (p = 0.005). On day 3 after operation, white blood cell counts were 13,020 +/- 1,220 elements/mm3 in the flash group versus 11,620 +/- 1,220 elements/mm3 in the 48-hour group (p = 0.03). A 48-hour antibiotic prophylaxis regimen decreases the rate of deep infections and particularly the rate of empyemas.

Bronchopneumonia↗
PubMed1993

Pretreatment with gonadotrophin releasing hormone (GnRH) analogue prior to in vitro fertilisation for patients with endometriosis.

To assess the effect of GnRH pretreatment prior to IVF-ET on fertilisation and pregnancy rates in patients with endometriosis compared with tubal infertility, a retrospective analysis of 228 cycles of tubal infertility cases (Group 1) and 92 cycles of endometriosis has been performed. Patients with endometriosis were classified by the revised AFS scoring system to two groups: 37 cycles of minimal and mild endometriosis (Group 2) and 55 cycles of moderate and severe endometriosis (Group 3). The GnRH analogue buserelin was used for pituitary desensitisation in all IVF cycles. Endometriosis patients have a minimum of 6 weeks GnRH treatment prior to superovulation therapy. Although the fertilisation rate per oocyte (51%) was significantly lower in Group 3 (P < 0.001), the percentage of cycles in which fertilisation occurred (86%, 78%, 78%) and the pregnancy rates per embryo transfer (17.7%, 17.2%, 18.6%) for Groups 1, 2 and 3, respectively, were not significantly different. Pretreatment with GnRH analogues allows patients with endometriosis to achieve similar success rates to patients with tubal infertility alone.

Adult↗
PubMed1993

The inhibition by fatty acids of receptor-mediated calcium movements in Jurkat T-cells is due to increased calcium extrusion.

Numerous studies on the molecular basis of the mechanism of action of fatty acids have demonstrated their action in cell signaling and particularly on the regulation of cytosolic Ca2+ concentration. Stimulation of Jurkat T cells with CD3 monoclonal antibody results in an increase of intracellular calcium concentration, [Ca2+]i due both to a release of Ca2+ from intracellular stores and a Ca2+ influx. [Ca2+]i increase represents a dynamic balance between Ca2+ influx and efflux. Fatty acids, either saturated (C14:0), monounsaturated (C16:1), or polyunsaturated, belonging to the C18 and the C20 series induce a marked decrease of CD3-induced [Ca2+]i rise. This property of fatty acid is independent of the position of the carbon-carbon double bond but specific of the cis stereoisomeric form. Fatty acids does not block CD3-induced signals but greatly stimulates the Ca2+ extrusion process probably by activating the plasma membrane Ca(2+)-ATPase. This was documented by the observation that fatty acids, reduced to the same extent as [Ca2+]i, elicited either with CD3 monoclonal antibody the calcium ionophore ionomycin or the Ca(2+)-ATPase inhibitor thapsigargin.

Antibodies, Monoclonal↗
PubMed1993

Apoptosis of activated CD8+/CD57+ T cells is induced by some combinations of anti-CD2 mAb.

Peripheral blood CD8+/CD57+ T cells display poor proliferative responses when stimulated with CD3 or CD2 in vitro, but can be induced to proliferate in the presence of exogenous IL-2. Although GT2+T11(1), a mitogenic anti-CD2 mAb pair, could synergize with IL-2 to induce sustained cell divisions in this population (as did immobilized OKT3), D66+T11(1), another anti-CD2 mAb pair, could only induce a small abortive proliferative response. All these antibodies were in contrast strongly mitogenic for CD8+/CD57- T cells. Assuming that D66+T11(1) were exerting inhibitory effects on CD8+/CD57+ T cells, we indeed found that such antibodies profoundly suppressed the anti-CD3 and IL-2-induced proliferation of those cells, but not that of CD8+/CD57- cells. CD2-mediated growth arrest was correlated with rapid cell death occurring within 2 h, once the cells had been submitted to D66+T11(1), and cells susceptible to the death signal were large cells committed in the cell cycle. D66+T11(1)-treated cells had the well-known ultrastructural form of apoptosis, and the DNA extracted from these cells showed the typical ladder pattern of DNA fragmentation accompanying this process. For apoptosis to occur, two anti-CD2 mAb had to be applied to the cells, one of them being D66, suggesting that the corresponding anti-CD2 mAb pairs were imposing on the CD2 molecule a particular conformational change appropriate to transduce a death signal. Notably, CD8+/CD57- T cells were largely resistant to apoptosis in the conditions just described. When exposed to anti-CD3 and IL-2 in primary and secondary cultures, CD8+/CD57+ T cells retained high viability, whereas in contrast, when exposed to D66+T11(1), important cell loss occurred, concomitant with apoptosis, illustrating the specificity of the CD2-derived death signal. Our results suggest that the expansion of CD8+/CD57+ T cells is critically dependent on the CD2 pathway which, according to the conformational change of the CD2 molecule and the activation state of the cells, will direct them either towards proliferation or towards cell death.

Antibodies, Monoclonal↗
PubMed1993

Monoclonal antibodies directed against the E2 protein (MIC2 gene product) induce exposure of phosphatidylserine at the thymocyte cell surface.

Monoclonal antibodies (mAbs) directed against E2, a 32-kDa transmembrane protein encoded by the MIC2 gene located in the pseudoautosomal region, induce a transbilayer movement of phosphatidylserine and, to a lesser extent, phosphatidylethanolamine in human thymocytes and a Jurkat T lymphocytes. The translocation of phosphatidylserine has been evidenced by using either derivatization of anionic phospholipids with trinitrobenzenesulfonate (TNBS) or cytofluorimetry after labeling of cells with antiphosphatidylserine antibodies. The perturbation of membrane phospholipids induced by anti-E2 mAbs was further evidenced by labeling the cells with merocyanine 540. The specificity of anti-E2-induced perturbations of membrane asymmetry was tested by using a number of mAbs able to activate T cells, including CD3 and CD2. The results strongly suggest that anti-E2-induced changes in PtdSer are related to cell aggregation since the same mAbs specifically induce the aggregation of both thymocytes and Jurkat cells and since the E2 molecule has been previously implicated in the adhesive properties of human T cells with erythrocytes.

12E7 Antigen↗
PubMed1993

Suppressive effect of T cell proliferation via the CD29 molecule. The CD29 mAb 1 "K20" decreases diacylglycerol and phosphatidic acid levels in activated T cells.

We had previously reported that the CD29 mAb "K20," presented in a soluble form, blocks peripheral T cell proliferation/activation induced by a CD3 mAb. To better characterize the negative signal delivered by soluble K20, we have investigated its effects on the phospholipid metabolism, both in Jurkat and CD4+ T cells. In CD3-activated T cells, K20 inhibited the increase of diacylglycerol (DAG) and phosphatidic acid levels, but did not modify phosphatidylinositol 4,5-bisphosphate levels, cytosolic Ca2+ raise, and inositolphosphates formation, indicating that K20 did not inhibit phosphatidylinositol 4,5-bisphosphate hydrolysis by phospholipase C-gamma. Moreover, in these conditions, K20 increased phosphatidylethanolamine levels, without variation of phosphatidylcholine, phosphatidylserine, and phosphatidylinositol, suggesting that K20 specifically increased the phosphatidylethanolamine biosynthesis from DAG. Thus, the effects of K20 on DAG and phosphatidic acid levels resulted from an accelerated catabolism rather than from a defect of synthesis. That K20 acts solely at an early step of T cell activation, namely before the binding of IL-2 to its receptor, is supported by the observation that adding exogenous rIL-2 increased proliferation in spite of K20. These results suggest that the beta 1 integrin molecules interact with the membrane phospholipid metabolism and they appear to be the hallmark of a peculiar negative pathway of T cell activation, likely to play an important regulatory role mediated via the T cell integrin molecules.

Antigens, CD↗
PubMed1993

Physical and functional interaction between WT1 and p53 proteins.

WT1 is a tumor-suppressor gene expressed in the developing kidney, whose inactivation leads to the development of Wilms tumor, a pediatric kidney cancer. WT1 encodes a transcription factor which binds to the EGR1 consensus sequence, mediating transcriptional repression. We now demonstrate that p53, the product of a tumor-suppressor gene with ubiquitous expression, physically associates with WT1 in transfected cells. The interaction between WT1 and p53 modulates their ability to transactivate their respective targets. In the absence of p53, WT1 acts as a potent transcriptional activator of the early growth response gene 1 (EGR1) site, rather than a transcriptional repressor. In contrast, WT1 exerts a cooperative effect on p53, enhancing its ability to transactivate the muscle creatine kinase promoter.

Animals↗
PubMed1993

Expression and characterization of human D4 dopamine receptors in baculovirus-infected insect cells.

The human D4 dopamine receptor has been genetically engineered for expression in insect cells using the baculovirus system. A D4 cDNA gene fusion construct [(1991) Nature 350, 610-614] was synthetically modified to remove two introns from the coding region, and expressed in S. frugiperda (Sf9) cells as a fusion with a short sequence from the polyhedrin protein. Binding assays with [3H]spiperone indicated high levels of D4 receptor binding 90 h after infection and a pharmacological profile identical to that reported for D4 receptors expressed in COS-7 cells using the cDNA gene hybrid. We also show that the agonist binding affinity of D4 receptors expressed in Sf9 cells can be shifted by GTP-gamma-S, indicating coupling to G-proteins.

Animals↗
PubMed1993

Ca(2+)-ATPase inhibitors induce interleukin-2 synthesis and T cell proliferation.

In Jurkat cells, the three Ca(2+)-ATPase blockers, thapsigargin, cyclopiazonic acid, and di-tert-butylhydroquinone (DtBuHQ) induced both a release of Ca2+ from intracellular stores and a Ca2+ influx. In contrast to CD3 mAb, the Ca(2+)-ATPase inhibitors did not induce the formation of inositol trisphosphate from the hydrolysis of phosphatidylinositides. Emptying intracellular Ca2+ stores was accompanied by a decrease of phosphatidylserine (PtdSer) synthesis as previously observed in PHA- or CD3 mAb-treated Jurkat cells. In the presence of a phorbol ester able to activate protein kinase C, TPA, the three Ca(2+)-ATPase inhibitors induced Jurkat cells to synthesize large amounts of interleukin-2 demonstrating that early signal transduction mechanisms can be bypassed by Ca(2+)-ATPase inhibitors. In purified human peripheral blood T lymphocytes, the same inhibitors induced moderate if any cytosolic Ca2+ rise, in the absence of external calcium. Nevertheless analysis of PtdSer synthesis suggested that intracellular stores were efficiently depleted by DtBuHQ and cyclopiazonic acid but not by thapsigargin. In contrast, the three compounds induced similar Ca2+ influx. However, in the presence of TPA, cyclopiazonic acid and DtBuHQ induce highly purified T cells to proliferate while thapsigargin did not, suggesting that the status of internal Ca2+ store may have a decisive role in T cell activation.

Calcium↗
PubMed1993

CD3 monoclonal antibodies evoke the same cytochrome P450-regulated capacitative entry of calcium as thapsigargin in Jurkat T cells.

In T cells CD3 monoclonal antibodies mediate an elevation of cytosolic Ca2+ concentration due to a release from internal stores and also due to an entry from extracellular medium, the mechanism of which is not clearly elucidated. Previous studies on several cell types have reported that depleting intracellular Ca2+ stores with inhibitors of the reticulum Ca(2+)-ATPase resulted in an increased plasma membrane permeability to calcium ions. It has been suggested that emptying the reticulum triggers a Ca2+ influx from extracellular medium, independent of phosphoinositide hydrolysis. To document the physiological relevance of such a mechanism, we compared CD3- and thapsigargin-induced sustained increase of cytosolic Ca2+ concentration in Jurkat T cells with regard to their sensitivity to internal and external Ca2+ level and to several inhibitors which do not affect the release of internal stores. We show that (1) there was no additivity of the two effects; (2) both CD3- and thapsigargin-evoked Ca2+ influx were inhibited when membrane was depolarized by either gramicidin or a high potassium concentration; and (3) Ca2+ influx was abrogated by cytochrome P450 inhibitors such as lipoxygenase inhibitors or imidazole antimicotic drugs. CD3 mAb and thapsigargin thus triggered the same signaling events, probably involving a cytochrome P450, to transmit information from depleted endoplasmic reticulum to the plasma membrane.

Calcium↗
PubMed1993

Vaccination of mice against canine distemper virus-induced encephalitis with vaccinia virus recombinants encoding measles or canine distemper virus antigens.

Measles and canine distemper are caused by serologically related viruses. Although dogs immunized with measles virus (MV) do not elicit canine distemper virus (CDV) neutralizing antibodies, they are protected against the fatal disease. To investigate the potential role of the MV antigens in protection against CDV, we have immunized mice with vaccinia virus (VV) recombinants expressing the MV haemagglutinin (HA), fusion (F), nucleoprotein (NP) and matrix (M) antigens and challenged them with CDV. A partial protection was observed with the VV recombinants expressing the F, NP and M antigens, but not the HA. In contrast, immunization with a VV recombinant expressing the CDV F protein completely protected mice from CDV.

Animals↗
PubMed1993

Age and prognosis of non-small cell lung cancer. Usefulness of a relative survival model.

The aim of our study was the comparative evaluation of a relative survival model and a Cox model to determine the prognostic factors of survival for patients with surgically cured non-small cell lung cancer (NSCLC). We focused particularly on the exact role of age in this survival. 156 patients treated between 1975 and 1988 were studied. Both univariate and multivariate analyses were performed, using the actuarial method and the Cox model for crude survival and the Hakulinen model for relative survival. This study confirmed the poor prognosis of NSCLC, even if a curative surgical procedure has been possible, with a 5-year survival of 48% for stage I tumours but only 6% for stage III tumours. The most significant prognostic factor was the postsurgical TNM staging. The relative survival method of Hakulinen dismissed age as a significant prognostic factor. Our study underlines the usefulness of relative survival methods which should be more frequently employed to allow comparisons between series of different origin and to set up multicentre therapeutic trials.

Adult↗
PubMed1993

The Wilms tumour gene WT1 is expressed in murine mesoderm-derived tissues and mutated in a human mesothelioma.

The tumour suppressor gene WT1 encodes a transcription factor expressed in tissues of the genito-urinary system. Inactivation of this gene is associated with the development of Wilms tumour a pediatric kidney cancer. We show that WT1 is also expressed at high levels in many supportive structures of mesodermal origin in the mouse. We also describe a case of adult human mesothelioma, a tumour derived from the peritoneal lining, that contains a homozygous point mutation within WT1. This mutation, within the putative transactivation domain, converts the protein from a transcriptional repressor of its target sequence to a transcriptional activator. The role of WT1 in normal development thus extends to diverse structures derived from embryonic mesoderm and disruption of WT1 function contributes to the onset of adult, as well as pediatric, tumours.

Adult↗
PubMed1993

Inactivation of WT1 in nephrogenic rests, genetic precursors to Wilms' tumour.

Nephrogenic rests consist of foci of primitive renal cells, typically microscopic, that are found within the normal kidney tissue of children with Wilms' tumour. To study the relationship between nephrogenic rests and the associated tumours, we screened these lesions for mutations in the 11p13 Wilms' tumour suppressor gene, WT1. In two cases in which the Wilms' tumour contained a somatic WT1 mutation, the nephrogenic rest had the identical mutation. Nephrogenic rests and Wilms' tumours are therefore topographically distinct lesions that are clonally derived from an early renal stem cell. Inactivation of WT1 appears to be an early genetic event which can lead to the formation of nephrogenic rests, enhancing the probability that additional genetic hits will lead to Wilms' tumour.

Amino Acid Sequence↗
PubMed1993

The in-vivo activity of co-amoxiclav with netilmicin against experimental methicillin and gentamicin resistant Staphylococcus epidermidis infection in rabbits.

This study compared co-amoxiclav, vancomycin and teicoplanin with and without netilmicin or amikacin for treating experimental subcutaneous fibrin-clot infection in rabbits due to a clinical beta-lactamase-positive methicillin- and gentamicin-resistant Staphylococcus epidermidis strain (MGRSE). MICs (mg/L) for this strain were: oxacillin 125, gentamicin 32, vancomycin 4, teicoplanin 8, netilmicin 1, amikacin 4, amoxycillin 64 with clavulanate at 2 mg/L. In rabbits treated with a single-dose i.v. regimen (netilmicin 8 mg/kg, amikacin 20 mg/kg, vancomycin 30 mg/kg, teicoplanin 15 mg/kg, co-amoxiclav 150-30 mg/kg), the bacterial count 24 h post-dose was reduced whatever the combination used (ANOVA, P < or = 0.001). Regimens were statistically classified in decreasing order of efficacy as follows: co-amoxiclav combined with netilmicin > vancomycin either alone or combined with either netilmicin or amikacin, teicoplanin with netilmicin > netilmicin and co-amoxiclav alone > teicoplanin or co-amoxiclav combined with amikacin, and teicoplanin alone > amikacin > no drug. From these findings, it is concluded that: co-amoxiclav could be useful for the treatment of beta-lactamase-positive and methicillin-resistant S. epidermidis infection; some enzyme-resistant aminoglycoside could be considered for treating gentamicin-resistant but netilmicin/amikacin-sensitive S. epidermidis infection; the combination of co-amoxiclav with netilmicin was synergistic and more rapidly bactericidal than vancomycin in this animal model.

Amoxicillin↗
PubMed1993

Brain structures selectively targeted by canine distemper virus in a mouse model infection.

Paramyxoviruses such as measles virus or canine distemper virus are etiological agents for acute and chronic encephalitis (measles inclusion body encephalitis, subacute sclerosing panencephalitis and chronic distemper encephalitis or old dog encephalitis). The mechanisms by which viral injury leads to neurological diseases have not yet been fully elucidated. We have developed an experimental model in mice in order to analyze the spatial and temporal distribution of canine distemper virus in the central nervous system. Cerebral target structures for viral replication were examined for the presence of viral material (proteins and mRNA) during the two stages of the biphasic disease. During the acute stage of infection all target areas could be identified by day 6 with a similar anatomical distribution in all the animals examined, which were either intracranially or intracerebroventricularly infected. Viral mRNA and proteins were selectively localized in certain brain structures such as the thalamus, hypothalamus, substantia nigra (pars compacta), locus ceruleus and raphe nuclei (dorsalis and centralis), and limbic system (hippocampus, septum, entorhinal and cingulate cortex, amygdala). The virus was apparently unable to replicate in cerebellum, striatum, a large part of cortex, or endothelial cells. During the subacute disease, viral material was no longer detectable except in a few structures such as hypothalamus up to 4-6 weeks after inoculation. After this time, all target structures were devoid of any labeling in spite of the occurrence of pathology (obesity, paralysis) during this viral quiescent phase. These results suggest that after the initial viral exposure, expression of viral genes in defined structures might disrupt central homeostasis and finally may lead to neurological or neuroendocrine diseases, even in the absence of the hallmarks of the virus.

Amygdala↗