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Biomedical subjects

M Fournier

Publications and source records attributed to M Fournier.

At least 109 records · Page 6Linked to original sources
PubMed1997

Immune functions in beluga whales (Delphinapterus leucas): evaluation of natural killer cell activity.

Natural killer (NK) activity, an important non-specific defense mechanism against viral infections and tumors, was demonstrated in beluga whales using two different methods: 51Cr release and flow cytometry. Using the 51Cr release assay, NK activity in belugas was shown to be higher against K-562 than against YAC-1 cell lines. Moreover, it was enhanced by the addition of human recombinant interleukin-2 with both cell lines. NK activity evaluated by flow cytometry in the peripheral blood of eight belugas increased when the effector:target cell (E:T) ratio increased, and averaged 13.9% +/- 3.8% (range 9.9% to 17.8%) at an E:T ratio of 100:1. While NK activity could be readily detected using both methods, the lack of radio-isotopes and related laboratory room make the flow cytometric method a viable and safe alternative. The evaluation of this function in cetaceans could lead to a better understanding of the early events that lead to viral epizootics in populations of marine mammals in different parts of the world, as well as to the high prevalence of neoplasms in St. Lawrence beluga whales.

Animals↗
PubMed1997

Immunomodulatory and protective effects of N-acetylcysteine in mitogen-activated murine splenocytes in vitro.

N-Acetylcysteine (NAC) is a pro-glutathione drug used to treat chronic lung disorders and because of its anti-AIDS virus activity in vitro, has been proposed for AIDS therapy. The effect of NAC on mitogen-activated-lymphocyte blastogenesis in C57B1/6 mouse splenocytes and ability of NAC to protect lymphocytes against mitogen-induced cytotoxicity was examined in vitro. NAC increased splenocyte proliferation in the presence of optimal and suboptimal concentrations of concanavalin A (Con A) and lipopolysaccharide (LPS). Stimulatory and costimulatory effects of NAC on mitogen-induced responses were also evident. The dose-response relationship describing the effects of NAC on lymphocyte proliferation with Con A-induced responses were enhanced in a dose-dependent manner, whereas the corresponding LPS-induced responses increased to a maximum level followed by decline in responses at higher concentrations of NAC. When splenocytes were incubated with inhibitory supraoptimal concentrations of Con A (10 microg/ml) or LPS (150 microg/ml), NAC partially enhanced the Con A-induced response but completely prevented the inhibitory effect of supraoptimal concentrations of LPS on splenocyte blastogenesis. Optimal and supraoptimal concentrations of Con A caused activation-induced cell death in the splenocytes whereas comparable concentrations of LPS did not produce a similar effect. Splenocyte cell death produced by the optimal mitogenic concentrations of Con A was completely blocked by the addition of NAC to cultures. Immunomodulation and protective effects of NAC were observed in mitogen-activated lymphocytes in vitro.

Acetylcysteine↗
PubMed1997

Effect of insulin-like growth factor I and/or growth hormone on diaphragm of malnourished adolescent rats.

Young growing animals appear to have significantly reduced "nutritional to short periods of unstressed starvation compared with adults, with resultant growth arrest and/or atrophy of diaphragm (Dia) muscle fibers. The aim of this study was to assess in an adolescent rat model of acute nutritional deprivation (ND; 72 h) the impact of insulin-like growth factor I (IGF-I), with or without added growth hormone (GH), on the cross-sectional areas (CSA) of individual Dia muscle fibers. Five groups were studied: 1) control (Ctr); 2) ND; 3) ND given IGF-I (ND/IGF-I); 4) ND given GH (ND/GH); and 5) ND given a combination of IGF-I and GH (ND/IGF-I/GH). IGF-I was given by a subcutaneously implanted osmotic minipump (200 microg/day), whereas GH was administered twice daily by a subcutaneous injection (250 microg every 12 h). Isometric contractile and fatigue properties of the Dia were determined in vitro. Forces were normalized for muscle CSA (i.e., specific force). Dia fiber type proportions were determined histochemically, and fiber CSA was quantified by using a computer-based image-processing system. Total serum IGF-I concentrations were significantly reduced in ND and ND/GH animals, compared with Ctr, and elevated in the groups receiving IGF-I. The provision of growth factors did not alter the contractile or fatigue properties of ND animals. Dia fiber type proportions were similar among the groups. In ND animals, there was a significant reduction in the CSA of types I, IIa, IIx, and IIc Dia fibers compared with Ctr. The administration of IGF-I alone or in combination with GH to ND animals significantly diminished the reduction in Dia fiber size. GH alone had no effect on Dia fiber size in ND animals. We conclude that with acute ND the peripheral resistance to the action of GH appears to be bypassed by the administration of IGF-I alone or in combination with GH.

Animals↗
PubMed1997

Anabolic influences of insulin-like growth factor I and/or growth hormone on the diaphragm of young rats.

It is controversial whether insulin-like growth factor I (IGF-I), growth hormone (GH), or their combination might enhance body growth and/or tissue anabolism in the well-fed animal with an intact somatotrophic axis. To assess this further, we studied four groups of adolescent rats: 1) control (Ctr), 2) GH, 3) IGF-I, and 4) GH/IGF-I. IGF-I was given via an osmotic minipump, whereas GH was injected subcutaneously for a period of 72 h. Diaphragm (Dia) contractile and fatigue properties were determined in vitro. Quantitative histochemical and morphometric analyses were performed on Dia fibers. Total serum IGF-I levels were significantly increased in the groups receiving growth factors. Although body weight increased to a greater extent in the animals receiving growth factors, a further synergistic effect was noted in the GH/IGF-I animals compared with either GH or IGF-I groups. Costal Dia mass was greater in the groups receiving growth factors. The Dia of GH/IGF-I animals was more fatigue resistant than the Dia in Ctr. The cross-sectional area of types IIa and IIx fibers were increased to a similar extent in all groups receiving growth factors compared with Ctr. Succinate dehydrogenase activity of type IIa fibers was significantly greater in the GH/IGF-I animals compared with the other groups. We conclude that the short-term provision of growth factors to well-nourished, normally growing adolescent rats can accelerate body growth and promote selective hypertrophy of predominantly type II Dia fibers.

Animals↗
PubMed1997

Progressive obstructive lung disease associated with microscopic polyangiitis.

Small airway involvement and progressive severe airflow obstruction are unexpected features in patients with microscopic polyangiitis. We report the case of a patient with microscopic polyangiitis and circulating anti-neutrophil cytoplasmic antibodies (ANCA), who developed pulmonary hyperinflation and airflow obstruction over a 7-yr period. Systemic manifestations of this vasculitis improved under corticosteriods and cyclophosphamid therapy, a treatment that did not influence either the very high level of anti-myeloperoxidase antibodies or the ventilatory impairment. Small airway involvement was suspected on the basis of pathologic small airway lesions and a mild emphysematous pattern on computed tomography (CT) scan, which was out of proportion with the severity of the obstructive lung disease.

Airway Obstruction↗
PubMed1997

Bronchial Kaposi's sarcoma after single lung transplantation.

Kaposi's sarcoma (KS) has been reported in 6% of malignancies of solid organ transplant recipients. Most of the observations have been in recipients of renal allografts but, so far, KS has not been described in lung transplantation. We report a case of bronchial KS occurring in a black patient 6 months after single lung-transplantation. Skin lesions were absent and, interestingly, KS lesions were observed solely in the trachea and the native lung. Following reduction of the immunosuppressive regimen a complete remission was obtained 1 year later. Up to the present time, this clinical remission is very encouraging, but close surveillance remains necessary to detect rejection episodes or the reappearance of KS following manipulation of the immunosuppressive therapy.

Bronchial Diseases↗
PubMed1997

Diagnostic accuracy of transbronchial biopsy in acute farmer's lung disease.

STUDY OBJECTIVES: To evaluate whether transbronchial biopsy (TBB) is useful for the diagnosis of acute farmer's lung (FL) by calculating the likelihood ratios (LHRs) of (1) simple pathologic criteria and (2) an overall assessment of the biopsy specimens. DESIGN: Retrospective study in which a blinded analysis of 105 TBBs with adequate material from patients with parenchymal diseases (55 cases of FL matched with 50 control samples) was performed by two independent pathologists. SETTING: Respiratory clinic of a university-affiliated referral center. MEASUREMENTS: Three pathologic criteria were first studied: (1) diffuse lymphocytic infiltration (LI); (2) focal LI; and (3) granulomas. Then, an overall assessment or the TBB was done. Four diagnostic categories were considered: (1) probable FL; (2) possible FL; (3) nonspecific; and (4) alternative diagnosis. LHRs favoring the diagnosis of FL were calculated for the pathologic criteria and for each diagnostic category. RESULTS: For both the pathologic criteria and the overall assessments, the interobserver agreement was fair. As a pathologic criterion, "diffuse LI" was better than "loosely formed granuloma" to discriminate FL from control samples (LHR, 9.1 [confidence interval, 2.2 to 37.0] vs 1.8 [confidence interval, 0.5 to 6.9]). After the overall assessment, as many as 48.6% of the TBBs were read as nonspecific. The LHRs of the four diagnostic categories were as follows: (1) probable FL: 1.1 (observer 1) and 2.6 (observer 2); (2) possible FL: 2.2 and 1.7; (3) nonspecific: 0.9 and 0.6; and (4) alternative diagnosis: 0.4 and 0.0. CONCLUSION: Hematoxylin-eosin-stained TBB specimen is of limited usefulness for the diagnosis of FL and should be reserved for patients with intermediate pretest probability of FL. Diffuse LI best discriminates FL from control samples and should be specifically sought.

Acute Disease↗
PubMed1997

Non-secretory multiple myeloma with multinucleated giant plasma cells.

We report a case of non-secretory multiple myeloma with unusual cytological features. The plasma cells were multinucleated and contained up to forty nuclei. All nuclei had regular outlines without multilobulated and convoluted slopes. DNA content measurement demonstrated that all nuclei of uni- and multinucleated cells were diploid. All plasma cells contained cytoplasmic alpha chain but light chains and their corresponding transcripts were absent. There is no clear explanation concerning multinuclearity. In addition, hypotheses regarding non-secretion of immunoglobulin in non-secretory multiple myeloma and in other B-cell neoplasias are discussed.

Aged↗
PubMed1997

Mixed anxiety and depression: from theory to practice.

The 10th International Classification of Disease (ICD-10) introduced the concept of mixed anxiety-depression to define patients presenting both anxiety and depressive symptoms of limited number and/or intensity, not sufficiently severe to fulfill criteria for a specific diagnosis of depressive or anxiety disorder. Epidemiologic surveys have shown that these patients may display significant levels of functional impairment, have unexplained somatic symptoms and a high use of nonpsychiatric medical care, have long-lasting symptoms, and are at risk for more severe psychiatric disorders. A DSM-IV field trial concluded that patients with affective-symptoms not meeting thresholds for DSM-III-R disorders were at least as common as patients with anxiety or mood disorders, and that their symptoms were associated with significant distress or impairment. Although some of these patients present residual symptoms from previous psychiatric episodes and may request treatment specific to these conditions, it is not known if those without a psychiatric history could benefit from pharmacologic or psychological treatments usually used in mild outpatient cases.

Adult↗
PubMed1997

[Lung volume reduction surgery in emphysema].

Lung volume reduction surgery in emphysema has, as an objective, the reduction of dyspnoea and an increase in the exercise tolerance in patients with respiratory insufficiency suffering from diffuse emphysema. In principle the resection of the most diseased areas of emphysema leads to improvement in the mechanical properties of the emphysematous lung and correct pulmonary hyperinflation. The respiratory function benefits both objective and subjective, produced by surgery are real but transitory and inconstant depending in particular on the evolutionary profile of the emphysematous disease. The indications should be further refined and an objective comparison of different surgical techniques has not been achieved. The impact on the quality of life for these patients is unknown.

Bronchoscopy↗
PubMed1997

[Selection criteria of candidates for lung transplantation].

Amongst the elements which contributed to the success of the early lung transplants at the beginning of the 1980's we feel that the careful selection of candidates probably played a predominant role. If some of the selection criteria initially described remain somewhat intangible, others have either been eased or have been invalidated. The experience acquired over the last 15 years has enabled to precise the optimal moment to include patients on the waiting list and to refine the choice for the type of surgical procedure according to the underlying disease. This article aims to review the different selection criteria for candidates for transplantation and stresses those which have recently undergone change.

Adrenal Cortex Hormones↗
PubMed1996

Interaction of human immunodeficiency virus type 1 reverse transcriptase with primer tRNALys3 and affinity modification of the enzyme by tRNALys3 derivatives.

The recognition of primer tRNA by retroviral reverse transcriptase is a crucial step in the replication of retroviruses. In the complex formed by HIV-1 reverse transcriptase and its natural primer tRNALys3, the heterodimeric enzyme, p66/p51, binds two molecules of tRNALys3 with different affinities. The same complex but in the presence of a non-complementary template, poly(A), gave higher Kd values. Preincubation of the reverse transcriptase with tRNA at concentrations comparable to the Kd2 value results in different levels of stimulation of the DNA polymerase activity: 300% in the absence and 70-80% in the presence of poly(A). The activation of the catalytically active p66 subunit is most probably mediated through tRNA interaction with the site of reverse transcriptase presenting the lower affinity. In this article, we describe the results obtained with new chemically reactive derivatives of tRNA bearing three or seven hydrophobic residues. Incubation of reverse transcriptase with tRNA derivatives, in the presence or absence of poly(A), leads to covalent binding of the reagents and inactivation of the enzymatic activity. However, during the initial step of the modification reaction, in the absence of poly(A), a slight stimulation of reverse transcriptase by tRNA derivatives took place, followed by a decrease in the enzymatic activity due to the covalent binding of tRNA derivatives to reverse transcriptase. In the presence of poly(A), enzyme inactivation occurs according to pseudo-first-order reaction kinetics. The affinities of tRNA derivatives for the p66/p51 heterodimer estimated from affinity modification data (Kd values) and from the inhibition of polymerization reaction (Ki values) were determined. Each analog of tRNA presented two Kd and two Ki values.

Animals↗
PubMed1996

Heavy metal-specific inhibition of phagocytosis and different in vitro sensitivity of heterogeneous coelomocytes from Lumbricus terrestris (Oligochaeta).

Cell viability and phagocytic activity of coelomocytes from the gastrointestinal tract of Lumbricus terrestris were examined by flow cytometry after in vitro exposure to heavy metals. Control coelomocytes were incubated for 18 h at 15 degrees C, 5% CO2, in Ca(++)-containing LBSS medium with 10(-4)-10(-9) M mercury chloride, methylmercury, cadmium chloride, zinc chloride, lead chloride or lead acetate. Heterogeneity of coelomocyte population was demonstrated by forward scatter (FSC) analysis and cytometric profile showing two different populations of type I/small (60%) and type-II/large (40%) cells. Exposure to either form of Hg, Cd and Zn was relatively highly toxic and affected both cell viability and phagocytosis, whereas Pb was relatively well tolerated by the coelomocytes. A fraction of cells within large coelomocyte population was exceptionally sensitive to the Hg-induced cytotoxicity, which did not affect, however, the relative phagocytic activity of the remaining cells. Overall, at least three different patterns of metal-specific toxicity, affecting both viability and phagocytic functions of earthworm coelomocytes, were confirmed in our in vitro studies. Further characterisation of both the target cells from heterogeneous coelomocyte population and the specific interaction of target cell-xenobiotic can possibly reduce biomonitoring problems in earthworm toxicology and immunotoxicology.

Animals↗
PubMed1996

[Pulmonary emphysema: surgical indications].

Surgery for pulmonary emphysema, with the exception of lung transplantation, is limited at present to resection of the emphysematous areas. The resection of a unique bulla within an otherwise healthy parenchyma can be indicated in case of complications but rarely in asymptomatic patients. When the bullae are large (i.e. volume greater than one-third of the hemithorax) in a patient suffering from diffuse emphysema, bullectomy is the ideal indication. Mortality varies from 0 to 10%, essentially due to infection or acute respiratory failure. In most patients, the subjective improvement in terms of dyspnea and the objective improvement as measured by spirometry remains significative up to 5 years after surgery. Inversely, surgical resection is classically considered to be contraindicated in patients with small poorly-limited bullae. Recent data would however question this idea since subjective and objective improvement after reduction of the lung volume is still present 1 year after surgery in most patients, even those with severe obstruction. The mechanism is probably related to increased elastic recoil. Even if only temporary improvement can be achieved for a few years, the persisting course of emphysema would suggest that volume reduction should always be entertained as an alternative before lung transplantation.

Humans↗
PubMed1996

Immune functions in beluga whales (Delphinapterus leucas): evaluation of mitogen-induced blastic transformation of lymphocytes from peripheral blood, spleen and thymus.

A quantitative assay was developed to evaluate mitogen-induced lymphoblastic transformation in beluga whales (Delphinapterus leucas) using peripheral blood mononuclear cells, splenocytes and thymocytes. Optimal concentrations of four different mitogens (Con-A, PHA, LPS and PWM) were determined with the use of standard curves. Addition of human recombinant IL-2 (rhIL-2) after 48 h in culture with the different mitogens suggests that Con-A, PHA and PWM, but not LPS, stimulate T cells in belugas, as they do in other animal species. The addition of 2-mercaptoethanol did not enhance significantly the proliferation of cells stimulated by Con-A, PHA and LPS, while it did with the cells stimulated by PWM and those cultured without mitogen. The proliferative response of cells was suppressed when the culture medium was supplemented by beluga serum instead of fetal calf serum. This assay will be useful to assess the status of the immune functions in different populations of beluga whales as well for further in vitro immunotoxicological experiments.

Animals↗
PubMed1996

Enzymatic conversion of adenosine to inosine and to N1-methylinosine in transfer RNAs: a review.

Inosine (6-deaminated adenosine) is a characteristic modified nucleoside that is found at the first anticodon position (position 34) of several tRNAs of eukaryotic and eubacterial origins, while N1-methylinosine is found exclusively at position 37 (3' adjacent to the anticodon) of eukaryotic tRNA(Ala) and at position 57 (in the middle of the psi loop) of several tRNAs from halophilic and thermophilic archaebacteria. Inosine has also been recently found in double-stranded RNA, mRNA and viral RNAs. As for all other modified nucleosides in RNAs, formation of inosine and inosine derivative in these RNA is catalysed by specific enzymes acting after transcription of the RNA genes. Using recombinant tRNAs and T7-runoff transcripts of several tRNA genes as substrates, we have studied the mechanism and specificity of tRNA-inosine-forming enzymes. The results show that inosine-34 and inosine-37 in tRNAs are both synthesised by a hydrolytic deamination-type reaction, catalysed by distinct tRNA:adenosine deaminases. Recognition of tRNA substrates by the deaminases does not strictly depend on a particular "identity' nucleotide. However, the efficiency of adenosine to inosine conversion depends on the nucleotides composition of the anticodon loop and the proximal stem as well as on 3D-architecture of the tRNA. In eukaryotic tRNA(Ala), N1-methylinosine-37 is formed from inosine-37 by a specific SAM-dependent methylase, while in the case of N1-methylinosine-57 in archaeal tRNAs, methylation of adenosine-57 into N1-methyladenosine-57 occurs before the deamination process. The T psi-branch of fragmented tRNA is the minimalist substrate for the N1-methylinosine-57 forming enzymes. Inosine-34 and N1-methylinosine-37 in human tRNA(Ala) are targets for specific autoantibodies which are present in the serum of patients with inflammatory muscle disease of the PL-12 polymyositis type. Here we discuss the mechanism, specificity and general properties of the recently discovered RNA:adenosine deaminases/editases acting on double-stranded RNA, intron-containing mRNA and viral RNA in relation to those of the deaminases acting on tRNAs.

Adenosine↗
PubMed1996

Laboratory evaluation of the Abbott Cell DYN 3500 5-part differential.

The study reports the performance of the Abbott CD3500 automated hematology analyzer for the enumeration and delineation of leukocyte populations for both adult and pediatric samples, and the ability of this instrument to detect the presence of abnormal cells. Samples from 542 individual patients either attending medical practitioners or during hospitalization were examined and then subdivided for the purposes of this study into 106 samples from newborn infants (< days), 145 samples from older children (15 days to 14 years) with non-oncologic disorders, 100 samples from normal adults, and 191 samples from oncology patient (97 adults and 94 children). The leukocyte differentials provided by both the Abbott CD3500 and the Coulter STKS were compared with those obtained from conventional morphology (two observers, total of 400 leukocytes). The sensitivities and specificities of the blast, immature granulocyte (IG) and NRBC "flags" were also determined. For the non-oncology adult (n=100) and pediatric (n=145) cohorts, automated differentials were given in all samples with the CD3500, whereas the STKS did not provide a differential analysis for 20 of the 145 (14%) pediatric samples, 11 of these were absent for no obvious reason. However, for the evaluable cases, the performances of the CD3500 and the STKS were broadly similar and generally correlated well with the manual reference procedure. The results for the newborn samples were less consistent with wider 95% confidence intervals (CI) noted. For example, the CD3500 (which reported a differential for all 106 samples studied) gave CI values of +/-14.4% for neutrophils, +/-14.6% for lymphocytes and +/-8.1% for monocytes. For comparison, the STKS (which did not provide a differential in 15% of 79 samples analyzed; insufficient material being available from the remaining 27 of 106 newborn samples) gave CI values of +/-21.9% for neutrophils, +/-23.5% for lymphocytes and +/-8.2% for monocytes. For all samples, the sensitivity of the blast flag on the CD3500 was 85% with a specificity of 91% (STKS: sensitivity, 75%; specificity, 85%); the sensitivity of the CD3500 IG flag was 72% with a specificity of 76% (STKS: sensitivity, 75%: specificity, 73%); and the sensitivity of the NRBC flag was 43% with a specificity of 94%(STKS sensitivity, 37%; specificity, 88%). This study confirms competitive performance levels for the CD3500 in the analysis of normal adult samples and suggests positive performance advantages in the study of neonatal, pediatric, and leukopenic samples.

Adolescent↗