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Biomedical subjects

C Roy

Publications and source records attributed to C Roy.

At least 73 records · Page 4Linked to original sources
PubMed1997

Ezrin is a cyclic AMP-dependent protein kinase anchoring protein.

cAMP-dependent protein kinase (A-kinase) anchoring proteins (AKAPs) are responsible for the subcellular sequestration of the type II A-kinase. Previously, we identified a 78 kDa AKAP which was enriched in gastric parietal cells. We have now purified the 78 kDa AKAP to homogeneity from gastric fundic mucosal supernates using type II A-kinase regulatory subunit (RII) affinity chromatography. The purified 78 kDa AKAP was recognized by monoclonal antibodies against ezrin, the canalicular actin-associated protein. Recombinant ezrin produced in either Sf9 cells or bacteria also bound RII. Recombinant radixin and moesin, ezrin-related proteins, also bound RII in blot overlay. Analysis of recombinant truncations of ezrin mapped the RII binding site to a region between amino acids 373 and 439. This region contained a 14-amino-acid amphipathic alpha-helical putative RII binding region. A synthetic peptide containing the amphipathic helical region (ezrin409-438) blocked RII binding to ezrin, but a peptide with a leucine to proline substitution at amino acid 421 failed to inhibit RII binding. In mouse fundic mucosa, RII immunoreactivity redistributed from a predominantly cytosolic location in resting parietal cells, to a canalicular pattern in mucosa from animals stimulated with gastrin. These results demonstrate that ezrin is a major AKAP in gastric parietal cells and may function to tether type II A-kinase to a region near the secretory canaliculus.

Amino Acid Sequence↗
PubMed1997

Benign hyperplasia in ectopic prostatic tissue: a rare cause of pelvic mass.

Four cases of a pelvic mass due to the development of benign hyperplasia within ectopic prostatic tissue are reported. They presented a hypoechoic homogeneous or heterogeneous pattern on transrectal ultrasonography and a high signal intensity on T2-weighted spin-echo sequences on MR. On CT the density was similar to that of prostatic tissue. No recent imaging findings of this rare entity have been described in the literature. Possible aetiologies are discussed. Even if it is a rare event, the correct diagnosis can be reached. It is important for radiologists to consider the presence of this lesion because of its benign nature.

Aged↗
PubMed1997

Small pelvic lymph node metastases: evaluation with MR imaging.

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

Adult↗
PubMed1997

Three determinants in ezrin are responsible for cell extension activity.

The ERM proteins--ezrin, radixin, and moesin--are key players in membrane-cytoskeleton interactions. In insect cells infected with recombinant baculoviruses, amino acids 1-115 of ezrin were shown to inhibit an actin- and tubulin-dependent cell-extension activity located in ezrin C-terminal domain (ezrin310-586), whereas full-length ezrin1-586 did not induce any morphological change. To refine the mapping of functional domains of ezrin, 30 additional constructs were overexpressed in Sf9 cells, and the resulting effect of each was qualitatively and semiquantitatively compared. The removal of amino acids 13-30 was sufficient to release a cell-extension phenotype. This effect was abrogated if the 21 distal-most C-terminal amino acids were subsequently deleted (ezrin31-565), confirming the existence of a head-to-tail regulation in the whole molecule. Surprisingly, the deletion in full-length ezrin of the same 21 amino acids provided strong cell-extension competence to ezrin1-565, and this property was recovered in N-terminal constructs as short as ezrin1-310. Within ezrin1-310, amino acid sequences 13-30 and 281-310 were important determinants and acted in cooperation to induce cytoskeleton mobilization. In addition, these same residues are part of a new actin-binding site characterized in vitro in ezrin N-terminal domain.

Animals↗
PubMed1997

Interstitial laser photocoagulation of osteoid osteomas with use of CT guidance.

PURPOSE: To evaluate interstitial laser photocoagulation (a minimally invasive percutaneous technique of thermal destruction of deep-seated tumors, with low-power laser energy) in local destruction of osteoid osteoma, with computed tomographic (CT) guidance. MATERIALS AND METHODS: Fifteen patients (age range, 8-48 years) with presumed osteoid osteoma were treated with CT-guided interstitial laser photocoagulation of the nidus. A high-power semiconductor diode laser (805 nm) with a 400-microm optical fiber was used. The fiber was introduced into the nidus through an 18-gauge needle. Around the fiber tip, well-defined coagulative necroses from 5 to 9 mm (energy delivery, 400-1,000 J) were obtained. RESULTS: Fourteen patients had complete pain relief, which was apparent within 24 hours in eight patients. One patient had recurrence of pain after 6 weeks. The remaining nidus was treated a second time, with complete relief. Treatment was unsuccessful in one patient, and surgical excision was performed. Daily activities were not restricted after the intervention. All patients were followed up for more than 1 year, with no sign of recurrence. The only notable complication was a mild reflex sympathetic dystrophy of the wrist in one patient. Sclerosis of the nidus was observed 4-6 months after the procedure. CONCLUSION: Percutaneous interstitial laser photocoagulation of osteoid osteoma seems to be a promising, simple, precise, and minimally invasive alternative to traditional surgical and percutaneous ablations.

Activities of Daily Living↗
PubMed1996

Assessment of painful ureterohydronephrosis during pregnancy by MR urography.

The purpose of this study was to assess the value of the fast imaging sequence called RARE (rapid acquisition with relaxation enhancement) MR urography (or RMU) in pregnant women with painful ureterohydronephrosis. A total of 17 pregnant women with an acute flank pain were examined with RMU. Results were compared with those of US, X-rays and the evolution of symptoms. The gold standard techniques used to evaluate the results of MR urography were US when it showed the entire dilated urinary tract and the nature of the obstruction (9 cases), limited intravenous urography (IVU) when performed (3 cases) or endoscopic procedure (5 cases). The accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (sensitivity 100% in our series). The determination of the type of obstruction, intrinsic vs extrinsic, was always exact. The RMU technique alone could not specify the exact nature of the obstruction. The RMU technique is able to differentiate a physiological from a pathological ureterohydronephrosis during pregnancy. It could be considered as the procedure of choice when US failed to establish the differential diagnosis.

Adult↗
PubMed1996

Natural history of abnormal conduction and its relation to prognosis in patients with dilated cardiomyopathy.

To investigate the natural history of disturbances in ventricular activation, atrioventricular conduction, and ventricular cavity size, we retrospectively studied 58 patients from a total of 296 patients with dilated cardiomyopathy seen within 4 years. A total of 309 computerised electrocardiograms (ECGs) and 135 M-mode echocardiograms were analysed. In the majority of the patients, PR interval, QRS duration and QT interval prolonged progressively, though heart rate changed little. Their increase was much more striking in patients who died (n = 10) or had a pacemaker inserted (n = 9), compared to that in the clinically stable patients, though at entry all these values, as well as age and left ventricular cavity size, were similar. There were no significant differences between patients who died and those with a pacemaker inserted, except for QRS axis, which had shifted rightwards in 8 out of 10 who died, but only in 3 of 9 who subsequently had a pacemaker inserted and 14 of the 29 stable patients. A QRS duration over 160 ms was found in 8 out of the 10 patients who died, 6 of 9 who had a pacemaker and only in 5 out of the 39 stable patients (P < 0.001). The sum of PR interval and QRS duration over 375 ms was not found in any stable patient but was present in 6 of the 7 patients who were in sinus rhythm and died (P < 0.001). Left ventricular cavity size also increased with time, but did not correlate significantly with ECG progression, nor did it identify patients who subsequently died. Thus, a combination of increasing PR interval and QRS duration, particularly along with rightwards shift of QRS axis, appears to be a marker of high risk in patients with dilated cardiomyopathy.

Adult↗
PubMed1996

[Acute basal ganglia necrosis with favorable course during Mycoplasma encepahlitis].

BACKGROUND: Acute bilateral striatal necrosis complicating the course of a post-infectious encephalitis is rare. CASE REPORT: A previously healthy 5-year-old boy presented with an atypical pneumonia; he rapidly developed, encephalitis revealed by a generalized status epilepticus. After transient improvement, he became confused and mutic, with dystonic postures of his limbs. Painful stimulation resulted in prolonged facial grimacing and doleful cry. CT scan and MRI showed abnormal signals in the whole basal ganglia, typical of bilateral striatal necrosis. Serologic tests for Mycoplasma pneumoniae were positive. The child recovered almost completely. CONCLUSION: A parainfectious process is probably responsible for the transient bilateral striatal necrosis seen in this patient who had Mycoplasma pneumoniae infection several days before the onset of neurologic symptoms. MRI seemed more reliable than CT-scan for the diagnosis of this condition.

Acute Disease↗
PubMed1996

Regulated assembly of connexin33 and connexin43 into rat Sertoli cell gap junctions.

Immunofluorescence and immunogold electron microscopy were employed to examine the assembly of connexins (Cx) 33, 37, and 43 into testis cell gap junctions in mature and postnatal rats. Cx37 was localized by immunofluorescence to the endothelia of blood vessels in both mature and immature testes and was not further characterized. Only Cx43 assembled into Leydig cell gap junctions, but Cx43 also co-assembled with Cx33 in some Sertoli-Sertoli gap junction plaques within and near Sertoli occluding junctions and on adluminal surfaces Assembly of Sertoli gap junctions appeared to be regulated according to the stage of the seminiferous epithelium since Cx33 (and Cx43) immunoreactivity was strong in Sertoli cells from stages II-VII but weak in stages IX-XIV. During postnatal maturation, assembly of Cx33 into gap junctions was regulated independently of Cx43 assembly. Cx43 was present on Sertoli cells of all tubules from postnatal Day 5 through Day 28. In contrast, Cx33 was not apparent on Sertoli cell surfaces until Day 15 and gradually accumulated in all tubules through Day 28. Between postnatal Days 38 and 43, the immunoreactivities of Cx33 and Cx43 became weak in Sertoli cells containing step 9-14 elongated spermatids. Thus, connexin abundance and gap junction composition in Sertoli cells is regulated during testis maturation and the cycle of the seminiferous epithelium.

Animals↗
PubMed1996

Assessment of habitual sun exposure in adolescents via questionnaire--a comparison with objective measurement using polysulphone badges.

The reliability and validity of sun exposure questions were examined in a group of 125 schoolchildren aged 14-15 years of northern European ancestry. We compared estimates of erythemally effective dose (EED) obtained from polysulphone badges worn on four consecutive weekend days in late spring to answers to several questions on habitual sun exposure. The polysulphone badge estimates accurately reflected the reported sun exposure of children and were highly correlated with responses to questions on habitual sun exposure obtained 12 months earlier. For the question "During weekends and school holidays, how much time do you usually spend in the sun each day", the Pearson correlation coefficients for the association with EED were 0.36 (girls) and 0.23 (boys). Adjusted for within-person variation in the EED measurements, the correlation coefficients were 0.65 (girls) and 0.43 (boys). For the question "Weekends and school holidays, where do you spend your time", the correlation coefficients were 0.18 (girls) and 0.32 (boys); the adjusted coefficients were 0.30 (girls) and 0.53 (boys). The findings suggest that "habitual' sun exposure in teenage children is a temporally stable behaviour that is reported with an acceptable degree of reliability and validity.

Adolescent↗
PubMed1996

Interventional radiologic procedures with CT guidance in cancer pain management.

Reduction of pain without systematic side effects can be achieved in advanced stages of cancer with precise percutaneous techniques guided with computed tomography (CT). CT guidance allows exact needle positioning, reducing complications and improving the results. Regional analgesia with neurolytic block (neurolysis) is achieved by injection of alcohol or phenol and involves intentional destruction of a nerve or nerves to interrupt nociceptive pathways for weeks or months. Percutaneous alcoholization of bone metastasis is indicated in patients with painful, severe, osteolytic bone metastasis if conventional anticancer therapy is ineffective and high doses of opiates are necessary to control pain and when rapid pain relief is necessary. Bone packing with acrylic glue (methyl methacrylate) is used to prevent pathologic fractures and pain in patients with vertebral body tumors and acetabular metastasis. With these techniques, the radiologist is able to play an active role in pain management and in improving the quality of life of patients with malignancies.

Bone Cements↗
PubMed1996

[Endovascular treatment of hemorrhagic renal angiomyolipoma with platinum microcoils].

Haemorrhage is the major complication of renal angiomyolipoma and is classically treated surgically, but embolization constitutes an alternative treatment. Improvement of catheters and embolization materials now allows highly selective embolization. The authors present a case in which the use of a variable stiffness catheter and platinum microcoils allowed highly selective embolization of a haemorrhagic renal angiomyolipoma while preserving the functional renal parenchyma.

Adult↗