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Biomedical subjects

P Dupuis

Publications and source records attributed to P Dupuis.

At least 19 recordsLinked to original sources
PubMed2002

New human microvascular endothelial cell lines with specific adhesion molecules phenotypes.

Vascular endothelial cells recognize blood-borne circulating cells and allow them to extravasate in a tissue-specific manner. Because this property determines the selectivity of lymphocyte homing, it is fundamental in physiological as well as pathological processes (inflammation, autoimmune diseases, metastasis). As a tool to assess the molecular basis of endothelium selectivity, microvascular endothelial cell lines of distinct tissue origin were established. Endothelial cells, isolated from lymphoid tissues (lymph nodes and appendix) and from nonlymphoid immune sites--intestine, lung, and skin--were immortalized in vitro. Their general endothelial characteristics, such as the presence of von Willebrand factor (wWf), angiotensin-converting enzyme (ACE), VE-cadherin, and the intracellular E-selectin, were preserved. This article shows that these cell lines display phenotypic characteristics related to their tissue origin. Hence, endothelial cells from lymph nodes expressed peripheral lymph node addressins (PNAds). Endothelial cells from nonlymphoid tissues were ICAM-1 (intercellular adhesion molecule-1) and CD49e positive, whereas P-selectin was not equally distributed among the cell lines. Endothelial cells from mucosal sites reacted with antibody against human MAdCAM-1 (mucosal addressin cell adhesion molecule). In the adhesion test, lymphoid and myeloid cells adhere to endothelial cell lines in a distinct manner. These lines could be useful to study molecular mechanisms involved in tissue-specific cell-cell interaction.

Animals↗
PubMed2001

Mug shot exposure prior to lineup identification: interference, transference, and commitment effects.

The effects of viewing mug shots on subsequent identification performance are as yet unclear. Two experiments used a live staged-crime paradigm to determine if interpolated eyewitness exposure to mug shots caused interference, unconscious transference, or commitment effects influencing subsequent lineup accuracy. Experiment 1 (N = 104) tested interference effects. Similar correct decision rates were obtained for the mug shot and no mug shot groups from both perpetrator-present and absent lineups. Experiment 2 (N = 132) tested for commitment and transference effects. Results showed that the commitment group made significantly more incorrect identifications than either the control or the transference group, which had similar false-identification rates. Commitment effects present a serious threat to identification accuracy from lineups following mug shot searches.

Adult↗
PubMed1996

Selective induction of peripheral and mucosal endothelial cell addressins with peripheral lymph nodes and Peyer's patch cell-conditioned media.

Vascular endothelial cell addressins play an important role in lymphocyte homing in secondary lymphoid organs and in chronic inflammatory areas. A SV40 large T antigen-immortalized cell line from peripheral lymph nodes, HECa1O [Bizouarne et al., 1993a], was used to characterize the location of addressins with regard to environmental factors and cytokines. For this purpose, two monoclonal antibodies, MECA 79 and MECA 367, specific for peripheral lymph node vascular addressin and for mucosal addressin (Peyer's patches), respectively, were bound to unstimulated HECa1O cells. Both mucosal and peripheral addressins were detected inside the cells and in cellular extracts of the resting cells. On the cell surface, both addressins could be evidenced on the same cells at a moderate level of expression. They partly mediate the EL4/EL4IL2 lymphoma cells' adhesion to HECa1O cells. Supernatants of cultured peripheral lymph node or Peyers' patch cells induced expression of MECA 79 or MECA 367 antigens, respectively, on the surface of HECa1O cells. Interleukins, IL-7, IL-3, and IL-8, induced the cell-surface appearance of MECA 79 but not of MECA 367 antigen. Therefore, the same cell type synthesizes both antigens, but the expression of these antigens on the cell surface is independently regulated, thus uncovering a characteristic tissue type-specific as well as environment-sensitive properties of microvascular endothelial cells.

Animals↗
PubMed1996

The causes of failure of lumbar transpedicular spinal instrumentation and fusion: a prospective study.

A prospective study was made of 101 patients who underwent transpedicular spinal instrumentation and fusion of the lumbar spine. All were reviewed by an independent observer. The objectives were to determine the causes of clinical failure and to recommend preventive measures. Forty-two primary and 59 revision operations were performed. The average age was 46 years and follow up 4 years. The variable screw placement and Cotrel-Dubousset systems were used. Posterior lumbar interbody fusion was carried out in 24 patients. The outcome was satisfactory after primary operations in 67% and after revisions in 46%. Nerve root injuries due to screw placement occurred in 4% (2% permanent and 2% transient). Instrumentation-induced foraminal stenosis developed in 2%. Proper surgical technique can avoid these complications. Predictive factors for failure are: abnormal psychology, symptomatic epidural fibrosis, inadequate decompression of lateral stenosis, surgical complications and the use of allografts.

Adolescent↗
PubMed1995

[Epidemic of viral gastroenteritis in an elderly community].

Rotaviruses and adenoviruses are the main aetiologic pathogens of gastroenteritis in infants. Adults may also be concerned with usually mild clinical symptoms. An epidemic of viral gastroenteritis occurred in a long-term hospitalization ward from July 25 to August 21, 1991: 101 patients. This study involved 26 females and 6 males with a mean age of 86 years (range 70-101 years), presenting clinical symptoms of gastroenteritis. The clinical attack rate was 27.7%. Outcome was favourable for the majority of patients who recovered in 4-5 days. The main clinical signs were diarrhoea (90.6%), hyperthermia (18.8%) and vomiting (18.8%). Virology investigations gave the diagnosis of 8 rotavirus infections, 6 adenovirus infections and 2 rotavirus and adenovirus mixed infections. Among staff members, 3 rotavirus and one adenovirus infections were diagnosed. The precise origin of the epidemic could not be determined from rotavirus electropherotypes obtained from stools of elderly and paediatric patients hospitalized during the same period. This outbreak recalls the viral involvement in diarrhoeal episodes of elderly people. These episodes of viral gastroenteritis are responsible for high morbidity in the elderly and may upset a precarious physiological state.

Adenovirus Infections, Human↗
PubMed1994

[The contribution of MRI in the study of glomus tumors].

The glomus tumors of the finger tip are benign. Their diagnosis is clinic but their precise localization is quite difficult by classic imaging. MRI with gadolinium injection seemed a good method to check exactly this lesion and have been tested on 20 patients suspected suffering of glomus tumor. On 18 glomus tumors surgically and histologically confirmed MRI examination have been positive for 16. In two cases MRI and surgery were negative. A good correlation seems observed with surgery for the size (7 tumor of 2 mm) the localization and osseus extension. Addition of T2 and T1 before and after injection weighted acquisitions improved the results. Precise informations on topography and size seems improved the surgical approach.

Adult↗
PubMed1994

Secondary expansion of a totally replanted scalp for aesthetic adjustment.

Total scalp avulsion is an uncommon and dramatic accident. Replantation is the only way for acceptable aesthetic final results. However, partial loss of tissue can result, and secondary procedures can be required. A total avulsion of a scalp involving the upper part of the right ear and both eyebrows was replanted after a long delay in our department. As a result, loss of a third of the hair-bearing area occurred. Secondary expansion of the replanted scalp achieved complete reconstruction.

Adult↗
PubMed1994

[Scalp reconstruction after avulsion: emergency microsurgery and secondary tissue expansion. Apropos of 3 cases caused by farming machines].

Total scalp avulsion is an uncommon accident. Three recent cases illustrate our surgical procedure. Small and central hair-bearing avulsed scalps can be treated by secondary scalp expansion (1 case). Large hair-bearing scalp (> 400 cm2) or including aesthetic relief should be treated by microsurgical reimplantation. Venous grafts allow vascular anastomoses beyond the intimal trauma area. Secondary expansion of reimplanted tissue (2 cases) eliminates scalp defects after initial necrosis. Thus, in the cases of total scalp avulsion even with high risk of failure (long time elapsed since injury, significant crush, part being in bad condition, two levels avulsion...), reimplantation has to be performed according to localization and size of avulsion. A secondary procedure with using expansion of the remaining replanted scalp is possible.

Accidents, Occupational↗
PubMed1993

[Chemonucleolysis. Its effectiveness in the treatment of lumbar diskopathies caused by compressive or rotational injuries].

One hundred patients who meet McCulloch's indicators for treatment of lumbar disc herniation by chemonucleolysis were entered in this study. Chemonucleolysis in the patients suffering from sciatica secondary to a compression injury, especially with clinical and radiographic evidence of nerve root compression at a single level, can be expected to attain good to excellent results. Chemonucleolysis is far less efficacious in patients suffering from either torsional injury or multiple level abnormality, especially in the absence of neurological deficit. Meticulous attention to patient selection will yield optimal results. The result was excellent or very good in 60% of patients, while in 40% the procedure failed. The rate of success at the L.5/S.1 level was 70%, at the L.4/5 level it was 63% and 37% were successful when multiple levels were treated.

Adult↗
PubMed1992

The beta-tubulin genes of Paramecium are interrupted by two 27 bp introns.

In the ciliate Paramecium tetraurelia, the analysis of the tubulin gene family has revealed the existence of four alpha and three beta genes. We show here that the coding sequence of the first beta-tubulin gene to be cloned and sequenced is interrupted by two short non-coding sequences of 27 bp each, which present at their extremities the pairs GT/AG, characteristic of eukaryotic pre-mRNA introns, and the internal pentanucleotide TTAAT, consensual in Tetrahymena introns. We demonstrate by PCR experiments that the three macronuclear beta-tubulin genes contain these sequences in similar positions, thereby ruling out the possibility that these sequences are ciliate IES present in the micronucleus and eliminated in the transcriptionally active macronucleus. S1 mapping analysis and mRNA sequencing show that the sequences are absent from the beta-tubulin transcripts. These sequences are the first introns described in protein encoding genes in P. tetraurelia and the shortest known introns altogether.

Amino Acid Sequence↗
PubMed1990

Expression of a ciliate gene in Escherichia coli using a suppressor tRNA to read the UAA and UAG glutamine codons.

Most ciliates use a particular genetic code where the standard stop codons UAA and UAG encode glutamine. Ciliate genes cannot therefore be expressed in heterologous systems such as Escherichia coli. To overcome this problem, we worked out a system of inducible suppression to permit efficient readthrough of UAAs and UAGs: a strong UAA tRNA suppressor that inserts glutamic acid was cloned downstream from a tac promoter whose efficiency was reduced by a transcription terminator. This system proved to be operational (1) to suppress UAG mutations by wobble pairing in an E. coli lacI-lacZ gene fusion and (2) to read through at least eight UAA glutamine codons in a Paramecium alpha-tubulin gene, as detected by Western blotting and colony hybridization. This work opens the way for cloning Ciliate genes from expression libraries and for expressing particular sequences without extended in vitro mutagenesis. A similar approach can be envisaged for expression of genes from Mycoplasma, mitochondria or other genomes that use non-standard genetic codes.

Animals↗
PubMed1986

Leukotriene B3, leukotriene B4 and leukotriene B5; binding to leukotriene B4 receptors on rat and human leukocyte membranes.

Specific high-affinity binding sites for [3H]-leukotriene B4 have been identified on membrane preparations from rat and human leukocytes. The rat and human leukocyte membrane preparations show linearity of binding with increasing protein concentration, saturable binding and rapid dissociation of binding by excess unlabelled leukotriene B4. Dissociation constants of 0.5 to 2.5 nM and maximum binding of 5000 fmoles/mg protein were obtained for [3H] leukotriene B4 binding to these preparations. Displacement of [3H]-leukotriene B4 by leukotriene B4 was compared with displacement by leukotriene B3 and leukotriene B5 which differ from leukotriene B4 only by the absence of a double bond at carbon 14 or the presence of an additional double bond at carbon 17, respectively. Leukotriene B3 was shown to be equipotent to leukotriene B4 in ability to displace [3H]-leukotriene B4 from both rat and human leukocyte membranes while leukotriene B5 was 20-50 fold less potent. The relative potencies for the displacement of [3H]-leukotriene B4 by leukotrienes B3, B4 and B5 on rat and human leukocyte membranes were shown to correlate well with their potencies for the induction of the aggregation of rat leukocytes and the chemokinesis of human leukocytes.

Animals↗
PubMed1985

Purification and characterisation of leukotriene A4 hydrolase from rat neutrophils.

Leukotriene A4 hydrolase was rapidly and extensively purified from rat neutrophils using anion exchange and gel filtration high-pressure liquid chromatography. The enzyme which converts the allylic epoxide leukotriene A4 to the 5,12-dihydroxyeicosatetraenoic acid leukotriene B4 was localized in the cytosolic fraction and exhibited an optimum activity at pH 7.8 and an apparent Km for leukotriene A4 between 2 X 10(-5) and 3 X 10(-5) M. The purified leukotriene A4 hydrolase was shown to have a molecular weight of 68 000 on sodium dodecylsulfate polyacrylamide gel electrophoresis and of 50 000 by gel filtration. The molecular weight and monomeric native form of this enzyme are unique characteristics which distinguish leukotriene A4 hydrolase from previously purified epoxide hydrolases.

Animals↗
PubMed1985

Importance of bound divalent cations to the tyrosine deprotonation during the photocycle of bacteriorhodopsin.

The transient absorption changes occurring at 297 nm during the photocycles of the deionized and acidified bacteriorhodopsins (blue membranes) were studied. As opposed to what happens during the photocycle of the purple membrane, for the blue membranes only the fast absorption increase corresponding to trans-cis isomerization of the retinal chromophore is present; the slow rise attributed to the tyrosine deprotonation is not observed. The addition of different salts to the deionized membrane restores the original color and causes a tyrosine deprotonation during the photocycle. This suggests that the presence of cations is required for the deprotonation of tyrosine as it is for the deprotonation of the retinylidene Schiff base. These results are discussed in terms of the recently proposed cation model for the observed deprotonation processes in the photocycle of bacteriorhodopsin.

Journal Article↗
PubMed1985

Unstable fractures of the thoracolumbar spine: a 10-year experience at Sacré-Coeur Hospital.

UNLABELLED: In a 10-year period, 108 unstable fractures involving the thoracolumbar junction (T11 to L2) were treated. This study evaluates the influence of the different treatments on the rate of complication, reduction of the fracture, and neurological recovery. METHODS: mechanism of injury, initial treatment and delay, neurologic deficit, operative findings, and duration of hospitalization were recorded. X-rays were reviewed for classification of fracture, measurement of deformity, and for instability scoring according to White and Panjabi's criteria. Seventy-seven patients were examined and nine more interviewed by telephone. RESULTS: a flexion-rotation injury occurred in 65% and a burst-fracture in 29%. A laminectomy was performed in 30 patients and Harrington instrumentation and fusion in 71 patients. Sixteen patients were treated conservatively. Fifty-five patients presented either a complete or partial neurological deficit. Seventy-five complications were noted and were more frequent in the laminectomy group. The instrumented group showed a clear tendency for earlier ambulation and discharge and pain level was found to be less. An increased residual deformity was found in patients treated by laminectomy, short fusion, and by nonsurgical modality. The neurologic recovery in the laminectomy and the nonlaminectomy group was not significantly different. Spinal realignment was better in the group where an instrumentation of five levels or more was performed and where posterior elements were not removed by laminectomy.

Adolescent↗
PubMed1984

Hormonal regulation of glucose transport in contracting skeletal muscle from normal and diabetic rats.

Using the hindlimb perfusion system, we have studied glycogenolysis and glucose transport in resting and contracting skeletal muscle from normal and diabetic rats. Glucose transport was measured using the glucose analogue 2-deoxyglucose. The muscles were treated for 15 minutes with either saline solution, insulin (1 mU/mL) or epinephrine (10(-7) mol/L) at rest and during electrical stimulation. In the resting muscle, basal glycogen was lower in diabetic rats (25 v 40 mumol/g), was not affected by insulin in either group, and was decreased by epinephrine in normal rats (to 26 mumol/g) but not in diabetic rats. Basal glucose transport was identical in the two groups (7.5 mumol/100 g/minute), was stimulated by insulin to a greater extent in diabetics (fivefold) than in normal rats (threefold), but was unaffected by epinephrine in either group. In contracting muscle, glycogen was decreased by 10 mumol/g in normal and diabetic rats independently of hormonal treatment. Basal glucose transport was not affected by muscle contraction with or without epinephrine, whereas the stimulatory effect of insulin on this process was blunted by such contraction (result, 10 mumoles/100 g/minute). We conclude that in normal and diabetic rats, muscle contraction stimulates glycogen breakdown independently of hormonal treatment; muscle contraction per se does not increase glucose transport; and finally, contracting muscle uses glycogen rather than circulating glucose as energy substrate.

Animals↗
PubMed1984

On the protein (tyrosine)-chromophore (protonated Schiff base) coupling in bacteriorhodopsin.

The kinetics of formation of both the tyrosinate ion (from its absorption at 296 nm) and the deprotonated Schiff base (M412) (from its absorption at 404 nm) are studied simultaneously at different pH values (7-11) and temperatures (5-25 degrees C). Two formation rates are observed for M412 in agreement with previous observations. The slow one is dominant under physiological conditions and is found to be slightly faster than that for the tyrosinate formation. This is in disagreement with the proposal that the tyrosinate formation is a prerequisite to the deprotonation of the Schiff base (M412). The ratio of the amplitudes of the fast and slow components is found to be sensitive to pH and, at any pH, it can be used to calculate an amino acid pKa value of 9.6. This is explained by proposing the existence of two sites for the protonated Schiff base within the protein. In one site, the Schiff base is near the neutral form of an amino acid residue with a pKa value of 9.6 (giving rise to the slow component), while in the other, it is near its conjugate base. The formation of the tyrosinate ion as well as the formation of the slow and fast components of M412 all have activation energies that are comparable to H-bond energies. A model is suggested to account for this and the comparable deprotonation rates of tyrosine and the slow component of the protonated Schiff base. It involves the reduction of their pKa by their exposure to a positively charged species.

Bacteriorhodopsins↗