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Biomedical subjects

C Roy

Publications and source records attributed to C Roy.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Value of asymmetry criterion in MRI for the diagnosis of small pelvic lymphadenopathies (inferior or equal to 1 cm)].

The purpose of this study was to determine if lymph node asymmetry in small (< 1.0 cm) pelvic nodes was a significant prognostic feature in determining metastatic disease. 216 patients who presented pelvic carcinoma underwent MR imaging. They were correlated to pathological findings obtained by surgery. We considered on the axial plan the maximum diameter (MAD) of both round or oval-shaped suspicious masses. Two different cut-off values were determined: node diameter superior to 1.0 cm (criterion 1) and node diameter superior to 0.5 cm with asymmetry relative to the opposite side for nodes ranging from 0.5 cm to 1.0 cm (criterion 2). With criterion 1 MR Imaging had an accuracy of 88%, a sensitivity of 65%, a specificity of 96%, a PPV of 88% and a NPV of 88% in detection of pelvic node metastasis. By considering criterion 2, MR Imaging had an accuracy of 85%, a sensitivity of 75%, a specificity of 89%, a PPV of 71% and a NPV of 91%. Normal small asymmetric lymph nodes were present in 5.6% of cases. Asymmetry of normal or inflammatory pelvic nodes is not uncommon. It cannot be relied on to diagnose metastatic involvement in cases of small suspicious lymph nodes, especially because of its low specificity and positive predictive value.

Adult↗
PubMed1995

Identification of a phosphatidylinositol-4,5-bisphosphate-binding domain in the N-terminal region of ezrin.

Purified human recombinant ezrin cosediments with large liposomes containing phosphatidylserine (PS). This interaction is optimal at low ionic strength. At physiological ionic strength (130 mM KCl) ezrin interacts strongly with liposomes containing > or = 5% phosphatidylinositol-4,5-bisphosphate (PIP2), the residual being phosphatidylcholine (PC). When PIP2 is replaced by phosphatidylinositol-4-monophosphate (PIP), phosphatidylinositol (PI) or PS, the interaction is markedly reduced. Furthermore we show, that a purified N-terminal glutathione S-transferase (GST) fusion protein of ezrin (1-309) still has retained the capacity to interact with PIP2-containing liposomes, whereas a C-terminal fusion protein (310-586) has lost this ability.

Binding Sites↗
PubMed1995

Association of reduced PR-AC interval with ventricular early potentials in dilated cardiomyopathy.

We studied 31 patients with dilated cardiomyopathy, correlating mitral valve cusp motion with the continuous wave Doppler signal of mitral regurgitation and the signal averaged electrocardiogram (ECG). Sixteen patients had a B point (early partial closure) on the mitral echogram and 15 did not. Fifteen normal cases were used as controls. The duration of ventricular early potentials (< 40 microV) was measured on the signal averaged ECG of the QRS complex. The PR interval was increased in patients with a B point (190 (33) ms vs. 145 (16) ms in normal, P < 0.01) and PR-AC interval was reduced (25 (71) ms vs. 65 (11) ms in normal, P < 0.05). The B point itself was effectively synchronous with the onset of low velocity early systolic mitral regurgitation, and followed the Q wave of the succeeding beat by 20 ms or less. Early low velocity on mitral regurgitation was not present in patients without a B point. The duration of early potentials was greatly increased in patients with a B point (43 (26) ms) compared both to those without (17 (20) ms, P < 0.01) and to normals (12 (7) ms, P < 0.01) and their duration correlated with B-C interval (r = 0.6, P < 0.02). We conclude that a B point on the mitral echogram in patients with left ventricular disease is due to early systolic low velocity mitral regurgitation which itself results from an abnormal pattern of left ventricular activation, probably bilateral bundle branch block. Once established, this low velocity jet delays complete mitral valve closure.

Adult↗
PubMed1995

A CD44 monoclonal antibody differentially regulates CD11a/CD18 binding to intercellular adhesion molecules CD54, CD102 and CD50.

We have made a monoclonal anti-CD44 antibody which is able to activate the leukocyte integrin CD11a/CD18. Activated T cells strongly aggregated, and the aggregation was shown to be intercellular adhesion molecule (ICAM)-1 (CD54) and ICAM-2 (CD102) dependent. Using purified ICAM coated on plastic, only binding to ICAM-1 was increased by the CD44 antibody, whereas activation by phorbol ester increased binding to both ICAM-1 and ICAM-3. The binding to ICAM-2 was not affected by either treatment. These findings show that the CD11a/CD18 integrin can be activated in a ligand-specific manner by engagement of CD44.

Antibodies, Monoclonal↗
PubMed1995

Heterogeneity of antigen expression among human umbilical cord vascular endothelial cells: identification of cell subsets by co-expression of haemopoietic antigens.

First described as an interface between blood and tissues, the endothelial cells are now known to be also involved in haemostasis, inflammatory and immune responses. Recent studies have reported that the endothelial cells represent a heterogeneous population of cells with organ-specific properties. This report describes the phenotype analyzed by flow cytometry of human umbilical vascular endothelial cells (HUVEC). For this purpose, we use monoclonal antibodies (Mabs) recognizing B cell antigens (CD10, 19, 20, 21, 22, 23, 24, 38, 40), T cell antigens (CD1, 2, 3, 4, 5, 6, 7, 8), myeloid antigens (CD13, 14, 15, 34, 35, 64), platelet antigens (CD9, 31, 51, 62P), NK and non-lineage cell antigens (CD16, 45, 56, 57), activation antigens (CD25, 30, 69, 71) and adhesion molecules (CD11a, CD11b, 29, 44, 54, 62E, 102, 106). Mabs recognizing MHC ClI or ClII molecules are also tested. Firstly, we show that HUVEC co-express some haemopoietic antigens with different levels of expression. Secondly, this study reveals that the HUVEC population does not represent a homogeneous cell population. Different endothelial cell subsets are identified. These phenotypical differences could reflect specialization of HUVEC performing different functions. The significant of haemopoietic antigen expression on the HUVEC surface will be discussed.

Antigens, CD↗
PubMed1995

Fast imaging MR assessment of ureterohydronephrosis during pregnancy.

PURPOSE: to assess the value of the fast imaging sequence called RARE-MR-Urography (RMU) for the diagnosis of pathologic ureterohydronephrosis during pregnancy. MATERIALS AND METHODS: 15 pregnant women with an acute flank pain were examined with RMU. Results were compared with those of ultrasonography (US), X-rays, and the evolution of symptoms. RESULTS: the accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (100%). The determination of the type of obstruction, intrinsic vs. extrinsic, was always exact. RMU alone cannot specify the exact nature of the intrinsic obstruction. Ultrasonography gave less sensitive information in terms of level (60%) and type of obstruction (53%). CONCLUSION: RMU is able to differentiate a physiological from a pathologic ureterohydronephrosis during pregnancy. It could be considered as a procedure of choice for special cases when US failed to establish this differential diagnosis.

Adult↗
PubMed1995

Superselective endo-vascular treatment of renal vascular lesions.

Embolization with platinum micro-coils delivered through the Tracker-18 micro-catheter was performed in 6 patients when peripheral selective catheterization with standard angiographic catheters was not possible. The patients had a total of 7 peripheral renal vascular lesions (3 arteriovenous fistulas, 2 false aneurysms, 1 direct vascular trauma and 1 arteriovenous malformation). In all patients we initially used platinum micro-coils as the embolic agent. Two patients required repeat embolization with glue. Endo-vascular treatment was technically successful in all cases and no complications were encountered. There was no renal parenchyma infarction in 3 patients and small peripheral infarctions (10 to 15% of the renal parenchyma) occurred in 3. Super selective endo-vascular treatment with a variable stiffness catheter is safe and useful technique when classical methods of embolization are not possible.

Adult↗
PubMed1995

[Imaging of connective tissue formations of the sub-umbilical anterior abdominal wall].

New high resolution imaging modalities (CT and MRI) can distinguish between bladder and anterior abdominal wall pelvic connective tissue. The main structure is the umbilicovesical fascia located anterior to the peritoneum and posterior to the transversalis fascia. This layer divides the space between an anterior prevesical space and a posterior perivesical space. An understanding of these spaces facilitates the clinical identification and topography of pelvic the fluid collections.

Abdominal Muscles↗
PubMed1994

[Loss of antibiotic sensitivity of Pseudomonas aeruginosa strains during treatment].

BACKGROUND: Loss of sensitivity to betalactamic, quinolones and aminoglucoside antibiotics has been described during treatment of infections produced by strains of Pseudomonas aeruginosa. Sixteen nosocomial strains isolated over a year during which sensitivity to one or several antibiotics of the above mentioned groups had been lost during the course of treatment were studied. METHODS: The strains were identified by conventional techniques. Sensitivity to antibiotics was studied by determination of the minimum inhibitory concentration in solid medium, according to the guidelines of the National Committee for Clinical Laboratory Standards. Plasmidic beta-lactamases were identified by analytic isoelectric focusing. Hyperproduction of chromosomic lactamase was studied by a qualitative technique. The 0 antigens were studied against rabbit antisera. The pyocinetype was determined according to the Fyfe method. Plasmids were detected by alkaline lysis extraction and electrophoresis in agarose gel. RESULTS: The 16 strains in which changes in sensitivity were observed during the course of treatment represent 4.47% of all P. aeruginosa isolates during one year. Loss of sensitivity to betalactamic antibiotics was observed in 10 strains, in one to aminoglucosides, in two to ciprofloxacin, simultaneously to aminoglucosides and ciprofloxacin in one and to betalactamic and ciprofloxacin in another two. Six of the 13 patients (46%) required a change in antibiotic treatment. CONCLUSIONS: The convenience of following the sensitivity of the strains of Pseudomonas aeruginosa isolated in a patients is suggested to thereby avoid therapeutic failure and the potential danger of clonal dissemination of the strains which have lost sensitivity.

Adult↗
PubMed1994

Triple-helix formation interferes with the transcription and hinged DNA structure of the interferon-inducible 6-16 gene promoter.

The interferon responsive element (IRE) of the 6-16 gene lies within two 39-bp elements in tandem. A purine-rich oligodeoxynucleotide, oligo(dN), was found to be able to pair with the purine-rich strand of the IRE in an antiparallel orientation which led to triple-helix formation with Mg2+ being necessary for triplex stability. Footprinting analysis confirmed these results. The interaction between the IRE and the oligo(dN) was reversible and had a Kd equal to 20 nM. The two repeats of the 6-16 gene IRE can form a hinged DNA structure through pairing of their purine-rich regions; exonuclease III experiments support this model. The hybrid DNA structure leads to a parallel pairing of the purine strands of the 6-16 gene IRE and this conformation was shown to be destabilized by triplex formation. When co-transfected with a reporter gene whose promoter was under the control of the 6-16 gene IRE, the triple-helix-forming oligo(dN)s inhibit the interferon-induced stimulation of the reporter gene with complete inhibition being obtained with 1 microM oligo(dN) at the time of transfection. When added to the cell culture medium after transfection, the concentrations of oligo(dN) needed to obtain 50% inhibition of the interferon effect on gene transcription must be 50-100 times higher. Besides the existence of a peculiar structure for the 6-16 gene IRE, the possibility of interfering with gene expression by means of oligo(dN)s is demonstrated.

Base Sequence↗
PubMed1994

Nature of ventricular activation in patients with dilated cardiomyopathy: evidence for bilateral bundle branch block.

OBJECTIVE: To investigate the nature of ventricular activation and its relation with mechanical events in patients with dilated cardiomyopathy. STUDY DESIGN: Retrospective and prospective study with 12 lead electrocardiograms, signal averaged electrocardiograms, and M mode and Doppler echocardiograms. SETTING: Tertiary cardiac referral centre. PATIENTS: 77 patients (mean (SD) age 59(13)) with dilated cardiomyopathy, four after aortic valve replacement and three after coronary bypass surgery, and six patients with a normal sized left ventricle and complete right bundle branch block were studied. 15 normal subjects (age 45(20)) were used as controls. RESULTS: In patients with dilated cardiomyopathy, QRS duration was longer (127(25) ms v 90(10), P < 0.05) than normal and was normally distributed (r = 0.991, P < 0.01) on a normal probability plot. 20 had classic left bundle branch block, 29 intraventricular conduction delay, four right bundle branch block, and one bifascicular block. The PR interval was prolonged (185(30) ms v 150(15), P < 0.05). Electromechanical delay, Q to the onset of thickening of the interventricular septum as seen on the transverse M mode echocardiogram, was 75(15) ms in controls, but reduced to 43(15) ms in the patients (P < 0.01). Q to the onset of mitral regurgitation was also short (50(15)) ms, and correlated inversely with PR interval (r = -0.67, n = 73, P < 0.01). Early potentials (< 40 microV) were recorded on the signal averaged electrocardiogram in 33 representative patients and in all controls. Their overall duration was 30(12) ms in the patients, much longer than normal (12(7), P < 0.01)). Early potential time correlated positively with PR interval (r = 0.75, P < 0.01) and QRS duration (r = 0.60, P < 0.01) on a 12 lead electrocardiogram, and negatively with apparent electromechanical delay (r = -0.71, P < 0.01, n = 33), but not with true electromechanical delay (73(15)ms) or true PR interval (163(30)ms), calculated by correcting apparent values for early potential. The onset of left ventricular free wall motion was delayed with respect to the septum beyond 95% of the upper normal limit in all the patients with classic left bundle branch block and intraventricular conduction defect. Motion in the right ventricular free wall was delayed in 13 of 20 patients with left bundle branch block and 24 of 29 with intraventricular conduction defect by 65(20) ms, similar to that (75(10) ms) in patients with right bundle branch block. CONCLUSION: In most patients with dilated cardiomyopathy and an electrocardiographic pattern of left bundle branch block or intraventricular block, the onset of mechanical systole is strikingly and symmetrically delayed in both ventricles, compatible with bilateral bundle branch block. Complete atrioventricular block does not occur. The ventricle is activated through the upper septum and this activation is detectable only by signal averaged electrocardiography. The anatomical substrates for this abnormal activation could be the high connections described by Mahaim and Winston.

Bundle-Branch Block↗
PubMed1994

Voltage-dependent gap junctional conductance in hepatopancreatic cells of Procambarus clarkii.

Properties of gap junction channels present between specific cell types constituting the hepatopancreas of the crayfish (Procambarus clarkii) were investigated using the dual whole cell voltage clamp technique. Four different cell types (E, Fe, R and B) were identified on the basis of their morphology using light and electron microscopy. Although junctional conductance (Gj) could not be measured in B-B cell pairs, junctional currents were resolved in both homologous and heterologous combinations of the other cell types. E-E, Fe-Fe, and E-Fe cell pairs exhibited strong dependence on inside-out voltage (Vi-o), such that Gj increased with hyperpolarization to a maximal plateau reached at approximately -40 mV and was abolished with depolarization > 10 mV. The Gj-Vi-o relationship can be described by a squared Boltzmann relation with A = 0.101 and V0 = 0.135 mV. In this system, sensitivity of the junctions to transjunctional voltage was slight, if present at all. Gating mechanisms were complex, as evidence by the presence of multiple unitary channel conductance states. Single channel recordings showed that large unitary conductances (> 200 pS) were generally found between E-E, Fe-Fe, and E-Fe cell pairs, whereas smaller channel sizes (< 90 pS) were detected between R-R cell pairs.

Animals↗
PubMed1994

Contributions to nursing science: synthesis of findings from adaptation model research.

Researchers who had used the Roy Adaptation Model (RAM) to guide their individual investigations collaborated to enhance knowledge development about adaptation of adults to actual and potential health problems. The purpose of this article is to present the synthesis of findings across selected studies that used the RAM. From this synthesis, middle-range theories were identified that in turn provided the scientific rationale for development and testing of clinical interventions. Contributions to the advancement of nursing science include a method to strengthen the relationships between research, theory, and practice; and increased understanding of the process of adaptation in adults; support for the efficacy of the RAM for nursing practice; and the benefit of collaboration between nursing researchers using the same model to guide their work.

Adaptation, Physiological↗