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J Bonnet

Publications and source records attributed to J Bonnet.

At least 91 records · Page 5Linked to original sources
PubMed1995

[Value of end diastolic pulmonary venous flow in the estimation of left ventricular diastolic pressure].

The aim of this study was to analyse the possible relationship between inversion of the end diastolic wave of pulmonary venous flow (Avp) recorded by transoesophageal echocardiography in the left superior pulmonary vein and left ventricular end-diastolic pressures (LVEDP) at cardiac catheterisation. In this series of patients, there was a poor correlation between the E/A ratio of transmitral blood flow and LVEDP. On the other hand, there was a better correlation between LVEDP and the difference of duration of the end diastolic Avp wave and the A wave of mitral flow. An even better correlation was found between LVEDP with respect to the contribution of atrial systole and the difference of duration Avp-A. When the pressure due to atrial contraction exceeds 15 mmHg, the difference between the durations of pulmonary and mitral A waves increases. Therefore, when the duration of the end diastolic Avp is greater than that of the mitral A wave, a LVEDP of over 15 mmHg may be predicted with a sensitivity of 88% and a specificity of 74%.

Adult↗
PubMed1994

An alternative splicing modifies the C-terminal end of tryptophanyl-tRNA synthetase in murine embryonic stem cells.

The cloning of murine tryptophanyl-tRNA synthetase revealed the existence of at least three messenger RNAs able to code for this enzyme. In most of the tissues tested, two major mRNA species were detected. They are produced by alternative polyadenylation and they share the same open reading frame. The deduced peptide sequence is highly homologous to bovine and human tryptophanyl-tRNA synthetases. In embryonic stem cells, a third type of mRNA was characterized. Surprisingly, this mRNA contains, at the C terminus of the open reading frame, a sequence coding for six additional amino acids. Southern blot and polymerase chain reaction analysis showed that the two open reading frames are encoded by the same gene. Thus, alternative splicing may generate two tryptophanyl-tRNA synthetase isoforms. This phenomenon is the first reported case for an aminoacyl-tRNA synthetase mRNA with two open reading frame isoforms. Moreover, to our knowledge, this is the first time that a peptide addition to the COOH terminus of a protein, by mRNA alternative splicing, is described. The extra hexapeptide, Cys-Phe-Cys-Phe-Asp-Thr COOH, resembles the consensus sequence found in C termini of Ras proteins.

Alternative Splicing↗
PubMed1994

Over-expression of MBP and PLP messenger RNA in 8-day-old trembler brain.

The trembler mouse suffers from a dominantly inherited mutation of the peripheral myelin protein 22 (PMP-22) gene which results in abnormal myelination of the peripheral nervous system. However, the clinical symptoms observed in the mutant suggest abnormalities in the central nervous system. Using the Northern blot technique, we investigated the steady-state levels of mRNA encoding myelin protein genes in 8-day-old normal and trembler brains. We measured a two- to four-fold increase for myelin basic protein (MBP) and proteolipid protein (PLP) mRNAS in the trembler samples. Whether a relationship exists between this observation and the onset of the clinical symptoms is still to be determined.

Animals↗
PubMed1994

Use of ferro-electric liquid crystal shutters for time-resolved fluorescence microscopy.

A technique is described to modify a standard fluorescence microscope for time-resolved visualization of delayed luminescing substances with decay times from 50 microseconds to several milliseconds. The modification consists of synchronized operation of a mechanical shutter, positioned in an aperture plane in the excitation pathway, simultaneously with a ferro-electric liquid crystal (FLC) shutter on the emission side. Operation of the microscope is through a microprocessor interfaced keypad by which all timing parameters can be adjusted for optimal suppression of fast decaying luminescence. Accuracy of the timing was within 1 microsecond. Prompt fluorescence was suppressed up to 10(6) times, as determined for bright prompt fluorescing microspheres. The use of the FLC shutter resulted in a reduction in emission intensity by a factor of 8 (due to the use of polarizers, the lower transmission of the FLC devices, and IR blocking filters). No significant image degradation due to shutter operations was observed. The modified microscope was successfully used for the visualization of delayed luminescing immunolabels, such as inorganic phosphor particles and lanthanide chelates, as well as naturally phosphorescing materials.

Equipment Design↗
PubMed1994

Phase II study of carboplatin (CBDCA) in refractory multiple myeloma. A Southwest Oncology Group study.

Nineteen patients with multiple myeloma resistant to standard alkylating agent therapy or to the VAD regimen received carboplatin at a planned daily dose of 100 mg/M2 on four successive days. Two patients erroneously received a four-fold higher drug dose resulting in bone marrow aplasia and death without antitumor effect in one patient with post-mortem examination. No anti-tumor effect was observed among 15 patients evaluable for response (two lacked follow-up examination of tumor markers). Major toxicities were hematologic and included grade > or = III, leukopenia in 9, thrombocytopenia in 6 and anemia in 3 of the 17 evaluable patients. Their median survival was 9 months. These results indicate that carboplatin is inactive in refractory multiple myeloma.

Adult↗
PubMed1994

Evaluation and comparison of urinary pyridinium crosslinks in two rat models of bone loss--ovariectomy and adjuvant polyarthritis--using a new automated HPLC method.

A specific HPLC system was developed to assess urinary excretion of collagen crosslinks (pyridinoline (Pyr) and deoxypyridinoline (D.Pyr)) in two models of osteopenia in rats, ovariectomy and adjuvant polyarthritis. The sensitivity of this method was in the picomolar range. In ovariectomized rats, a specific model of bone resorption, Pyr and D.Pyr levels rose early, reaching a peak 2 weeks after surgery. Both levels remained raised during the whole observation period (6 weeks) with no change in the Pyr/D.Pyr ratio. So, in this high bone turnover model, hyperresorption is reflected by the parallel increase of both crosslinks resulting in a significant decrease of bone mineral density (BMD) at 6 weeks (-7.3% vs. control). In polyarthritic rats, in the 2 post-adjuvant weeks, Pyr levels increased in parallel with inflammatory parameters, whereas D.Pyr levels remained unchanged. This is in agreement with our previous report that at the end of the 2nd week after adjuvant there is no change in bone resorption. From the 3rd week, both Pyr and D.Pyr increased. The Pyr/D.Pyr ratio was always significantly higher in polyarthritic rats. These results suggest that the early increase of Pyr level reflects non-osseous collagen breakdown and that bone resorption occurs at a later stage when D.Pyr rises, leading to a dramatic decrease of BMD at 4 weeks (-17.7% vs. control). Taken together, our results suggest that in rat as in human, urinary Pyr is a marker of bone and cartilage breakdown, whereas D.Pyr is a specific marker of bone loss. This automated method described may constitute a very useful tool to evaluate bone and/or cartilage breakdown in rats and for the assessment of protective treatments.

Amino Acids↗
PubMed1994

Quantitation of mRNA species by RT-PCR on total mRNA population.

PCR is commonly used for mRNA quantitation. Previously described procedures are applied to one or a few specific mRNA sequences. We show here that methods used for amplifying heterogeneous cDNA populations can be applied to the quantitation of many mRNA species. This quantitation is achieved by dot blotting and hybridization with the corresponding probes after amplifying a bulk mRNA population. Only a single, two-round-amplification assay is required for quantitation of a whole set of mRNA species. The proportionality of input molecules to output signal was shown by performing a series of control experiments. We applied this technique to measure the relative variations of the MBP, Po, and MAG mRNA sequences in the normal trembler mouse model. The results were consistent with previously described Northern blot data. This quantitative PCR method provides a rapid and reliable way to quantify relative amounts of mRNA species in small amounts of total RNA by using internal controls.

Animals↗
PubMed1994

Regulation of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in human vascular smooth muscle cells.

Vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin are inducible proteins involved in cell-cell adhesion. Immunohistochemical studies have indicated that human atherosclerotic plaques contain smooth muscle cells (SMCs) that express ICAM-1 and VCAM-1. Recently, we demonstrated that SMCs in culture express a functionally active cytokine-inducible ICAM-1. SMCs and mononuclear cells participate in the local accumulation of cytokines and related growth factors in atherosclerotic lesions. Therefore, we determined the effects of different cytokines and growth factors on mRNA content and cell surface expression of VCAM-1, ICAM-1, and E-selectin in cultured human aortic SMCs by Northern blotting, quantitative polymerase chain reaction amplification, and immunofluorescence flow cytometry. Under basal conditions of cultivation, both VCAM-1 mRNA and membrane expression of VCAM-1 were low and were induced very little by interleukin-1 beta (100 U/mL). Platelet-derived growth factor or transforming growth factor-beta decreased VCAM-1 mRNA basal expression. Treatment of SMCs with tumor necrosis factor-alpha (TNF-alpha) led to an increase in both VCAM-1 mRNA and cell surface expression for VCAM-1 in a dose- and time-dependent manner. Interferon-gamma induced a weak increase in VCAM-1 mRNA expression, with no synergistic effect on the stimulation by TNF-alpha. Various differences were noted between the expression of ICAM-1 and VCAM-1 genes, because interleukin-1 beta induced substantial amounts of ICAM-1 but not VCAM-1. The addition of interferon-gamma delays the time at which peak expression of ICAM-1 in response to TNF-alpha stimulation occurs. Under our conditions, we did not detect any expression of E-selectin by SMCs. These results suggest that cytokines regulate VCAM-1 and ICAM-1 expression on arterial SMCs and could play an important role in the pathophysiology of inflammatory and immune processes in atherosclerosis.

Base Sequence↗
PubMed1993

Tetrapeptide tachykinin antagonists: synthesis and modulation of the physicochemical and pharmacological properties of a new series of partially cyclic analogs.

We report on the synthesis and the pharmacological properties of a new series of tachykinin antagonists based on the pseudopeptide pharmacophore cyclo[-Abo-Asp(D-Trp-Phe-N(Me)Bzl)-] which contains the 2-azabicyclo[2.2.2]octane-3(S)-carboxylic acid (Abo) residue. Variation of the substituents on the tryptophan indole nitrogen was shown to modulate water solubility and transport properties of the analogs as well as potency in classical in vitro response and binding assays. One water-soluble compound, 16, in which the substituent was 3-carbonylpropionate, strongly prolonged the reaction time in the mouse hot-plate test both after iv or oral administration and was devoid of degranulating activity in rat peritoneal mast cells.

Analgesics↗
PubMed1993

Preparation of an anti-acid sphingomyelinase monoclonal antibody for the quantitative determination and polypeptide analysis of lysosomal sphingomyelinase in fibroblasts from normal and Niemann-Pick type A patients.

An anti-acid sphingomyelinase monoclonal antibody has been prepared using an in vitro booster technique. The antigen, acid sphingomyelinase, was purified from human placentas by sequential chromatographic steps in the presence of the non-ionic detergent Nonidet P40. This monoclonal antibody (MAB 236) precipitates specifically the enzyme activity by immunoadsorption techniques and presents the same specificity to normal and mutated sphingomyelinase in Niemann-Pick type A patients. MAB 236 is the first antibody able to precipitate the protein in the presence of detergent thereby permitting the quantitative determination of normal and mutated sphingomyelinase in tissue and cell extracts. Polypeptide analysis and quantitative determination experiments using this monoclonal antibody showed no difference between patients and normal controls.

Antibodies, Monoclonal↗
PubMed1993

Novel nonopioid non-antiinflammatory analgesics: 3-(aminoalkyl)- and 3-[(4-aryl-1-piperazinyl)alkyl]oxazolo[4,5-b]pyridin-2(3H)-ones.

A series of 3-(aminoalkyl)- and 3-[(4-aryl-1-piperazinyl)alkyl]oxazolo[4,5-b]pyridin-2(3H)-ones were prepared from their respective oxazolo[4,5-b]pyridin-2(3H)-ones. Several members of this group were found to possess potent analgesic activity in the mouse during a p-phenylquinone writhing induced test. Among them, phenylpiperazine compounds with two-carbon length alkyl chains, 2a and 2b, appeared by high analgesic with little toxicity having neither an antiinflammatory effect nor opioid receptor affinity. The synthesis and structure-affinity relationships for this series are detailed.

Amino Acid Sequence↗
PubMed1993

Bone morphometric changes in adjuvant-induced polyarthritic osteopenia in rats: evidence for an early bone formation defect.

Adjuvant polyarthritis (AP) in rats is known to result in extensive bone loss. This study investigates the mechanisms responsible for the early trabecular osteopenia evaluated at a single point in time--2 weeks after adjuvant injection--in the hindpaw of female Lewis rats using biochemical and histomorphometric methods. At this early point in time, the inflammation was generalized (inflammatory score, 20; albumin/globulin, -80% versus control). Histomorphometric analysis of the noninjected femur showed that the trabecular bone volume was significantly decreased (-28% versus control) in both proximal and distal parts, and the femur growth rate was unaffected. The trabecular osteopenia was associated with a 90% decrease in osteoid surface and a concomitant thinning (-19%) of the trabeculae. Both the double-fluorescence-labeled surface and the osteoblast surface were also markedly decreased (-75%). In addition, the mineral apposition rate was reduced (-50%) and the bone formation rate was decreased by as much as 90%. The trabecular bone volume was decreased in relation with the extent of double-fluorescence labeling (r = 0.38, p = 0.03) and bone formation rate (r = 0.42, p = 0.01), suggesting that the generalized osteopenia resulted from the reduced bone formation. This was associated with a 26% reduction in plasma osteocalcin. Neither the osteoclast surface nor the number of osteoclasts was consistently affected. However, urinary hydroxyproline was increased by 100-200%, which likely reflected the cartilage and bone destruction at the site of injection. The present data show that the early extensive osteopenia observed 2 weeks after AP induction in rats results from defective bone formation with unchanged bone resorption. The role of cytokines in such an inhibitory effect on bone formation remains to be determined.

Animals↗
PubMed1993

Quantitative analysis of polymerase chain reaction products using biotinylated dUTP incorporation.

A method for relative quantitation of specific mRNA species by polymerase chain reaction (PCR) has been developed by using the incorporation of biotinylated dUTP. Transferred biotinylated PCR products gave a sensitive colorimetric signal which could be quantitated by video analysis. In the exponential phase of amplification, the linearity and reproducibility of reverse transcription and PCR demonstrated the same efficiency of cDNA synthesis and PCR for the two target genes, ICAM-1 and beta-actin, and allowed the normalization of ICAM-1 expression. These results suggested that in the exponential phase of amplification a relative quantitation of mRNA could be determined. We used this approach to analyze the different effects of TNF-alpha, IL-1 beta, and purified porcine platelet-derived growth factor stimulations on ICAM-1 expression in smooth muscle cells.

Base Sequence↗
PubMed1993

Multicolour preparations for in situ hybridization using precipitating enzyme cytochemistry in combination with reflection contrast microscopy.

We have further developed a method for the detection of different enzyme cytochemical reaction products by means of reflection contrast microscopy (RCM). By embedding these enzyme precipitates in a protein matrix, we were able to prevent the reaction products from dissolving in immersion oil, which is required for RCM analysis. The applicability of the RCM procedure is, therefore, extended to a range of cytochemical enzyme precipitation methods, which normally result in oil soluble reaction products. To test their usefulness, these enzyme precipitates have been used in single- and well as double-label in situ hybridization (ISH) procedures to visualize a number of DNA target sequences by several different reflection colours, i.e. white, yellow and red. Three repetitive DNA probes for the (sub)centromeric regions of chromosomes 1, 7 and 17, as well as a repetitive DNA probe for the telomeric region of chromosome 1, and two cosmid DNA probes (40 kb each) for both arms of chromosome 11 could be detected with high efficiency in both interphase and metaphase preparations. Moreover the enzyme precipitates were shown to be stable upon exposure to excitation light or upon storage. It may be concluded that these findings render RCM a sensitive method for the visualization of multiple targets in biological specimens.

Carcinoma, Transitional Cell↗
PubMed1993

Reflection contrast microscopy of ultrathin sections in immunocytochemical localization studies: a versatile technique bridging electron microscopy with light microscopy.

Reflection contrast microscopy (RCM) of ultrathin sections was recently introduced as a sensitive technique for visualization with enhanced definition in immunogold histochemistry. Experience of using RCM as a major tool in immunocytochemical research in different fields is summarized, e.g. oncology, nephrology and embryology. The sensitive visualization of immunocytochemical labels, gold particles or peroxidase-diaminobenzidine deposits in or on ultrathin sections, by RCM instead of electron microscopy is demonstrated. RCM of ultrathin sections is an adequate light microscopical alternative for immunoelectron microscopy, since an overview of both label and tissue is obtained with a high image definition and high contrast of label. In the studies presented, RCM is shown to provide a better gradation in staining intensity and staining pattern than other light microscopical methods. Moreover, a precise localization of multiple labels is obtained with this method. Besides the applications shown, ultrathin section visualization by RCM is very useful for correlative light- and electron microscopical studies of fine structures. Commercially available fluorescence microscopes can be adapted for proper RCM functioning; an adaptation scheme and list of microscopes tested is provided.

Animals↗
PubMed1993

Effect of low density lipoprotein on monocyte adhesiveness to endothelial cells in vitro.

Adhesion of monocytes to the endothelium is an early event in the development of atherosclerosis. The possibility that low density lipoproteins enhance this process by activating monocytes was investigated using an in vitro adhesion test on endothelial cell monolayer cultures. Preincubation of monocytes with low density lipoprotein (LDL) (100 micrograms LDL protein/l x 10(6) cells/ml) for 15 min induced a 70% increase in adhesion to endothelial cells with a maximal effect at 100 micrograms LDL protein/ml and a short latency of effect (2 min). Anti-LDL receptor antibody, which inhibited LDL binding, blocked this activation. The LDL effect appeared to depend on receptor binding of LDL rather than on receptor-mediated endocytosis, since preincubation of monocytes with LDL at either 4 degrees C or 37 degrees C resulted in the same stimulation of adhesion. A cytofluorimetric study using integrin monoclonal antibodies (MAbs) against CD18 and CD11b did not reveal any increase in expression of the integrins on the surface of LDL-activated monocytes. However, a 30-min preincubation of monocytes with anti-CD18 abolished the LDL-activated adhesion. These results indicate that LDL induces a rapid activation of monocyte adhesiveness to endothelial cells. This effect appears to be mediated by interaction of LDL with its receptor rather than LDL-receptor complex internalization or integrin membrane mobilization from intracellular pools. The integrin system nevertheless appears to be involved.

Antibodies, Monoclonal↗
PubMed1993

Biological risk factors for restenosis after percutaneous transluminal coronary angioplasty.

In an attempt to discern biological (such as thrombotic or fibrinolytic) risk factors in patients developing restenosis after percutaneous transluminal coronary angioplasty, the following factors were measured prior to angiography in a population of 23 patients (20 men, 3 women, mean age 57 +/- 5 yr) treated by a successful angioplasty (gain > 20% and residual stenosis < 50%) for stable angina pectoris and who had a routine angiographic restudy. The following factors were thus assessed: lipid factors: cholesterol, triglycerides, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein AI, apolipoprotein B; coagulation factors: fibrinogen, antithrombin III, fibrinopeptide A, factor VIII coagulant, factor VIII antigen, protein C; factors of physiological fibrinolysis: plasminogen, alpha 2-antiplasmin, tissue plasminogen activator and euglobulin clot lysis time before and after venous occlusion, plasminogen activator inhibitor before venous occlusion; and factors of platelet release: beta-thromboglobulin, platelet factor 4. Also studied were clinical characteristics: age, gender, diabetes, hypertension, smoking habits, previous myocardial infarction; angiographic data: global extent of coronary artery disease, location of the stenosis in a bend or branch point, complexity of the lesion, initial and residual stenosis and treatment during follow-up. The coronary angiograms were analyzed by a computer-assisted method with automatic edge detection. On angiographic criteria, 6 patients (restenosis group) were judged to have developed a restenosis (30% decrease in diameter and/or return to a 50% stenosis). The other 17 patients (those without restenosis) were considered to have a persistent success. Apart from age (group without restenosis: 55 +/- 6; restenosis group 61 +/- 5, p < 0.04), there were no differences in clinical, angiographic or treatment variables. There were no differences in lipid factors, but significant differences were observed in hemostatic variables: fibrinogen (without restenosis: 3.18 +/- 0.83; restenosis: 3.83 +/- 0.51 milligrams, p = 0.05), tissue plasminogen activator before venous occlusion (without restenosis: 10.9 +/- 26.8; restenosis: 232.5 +/- 371.2 IU, p < 0.04), euglobulin clot lysis time after venous occlusion (without restenosis: 176.5 +/- 100.5; restenosis: 78.6 +/- 40.2 min, p < 0.05) and for marker of the platelet release: platelet factor 4 (without restenosis: 10.8 +/- 7.9; restenosis: 20.5 +/- 7.5 ng/l, p < 0.04). These findings indicate that patients developing restenosis after coronary angioplasty tend to have an imbalance in the prothrombotic-antithrombotic equilibrium prior to the procedure.

Aged↗