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Biomedical subjects

M Laurent

Publications and source records attributed to M Laurent.

At least 19 recordsLinked to original sources
PubMed1992

Cloning of two different 5' untranslated exons of bovine acidic fibroblast growth factor by the single strand ligation to single-stranded cDNA methodology.

In an attempt to characterize the 5' UTR of the aFGF mRNAs we used the new anchored PCR methodology, single strand ligation to ss-cDNAs (SLIC). In bovine brain and retina, two kinds of aFGF cDNA clones were isolated. They contained two alternative exons located 34 bp upstream to the translation initiation codon ATG. Taking into account the number of clones specific for each exon, the two mRNAs are expressed with the same ratio in both tissues. One of these bovine 5' UTR exons (136 bp) showed 81% identity to a human 5' UTR exon, the second one (323 bp) was 70% identical to the second human 5' UTR exon with a central region of 90 nucleotides showing 41% identity. The conservation of the splicing positions for these 5' UTR alternate exons in both bovine and human species, suggests that the overall structure of the aFGF gene is conserved in mammals. Furthermore, the conservation of the nucleotide sequences and of the localization of these 5' UTR exons suggests that these non-coding regions may be involved in the control of aFGF gene expression.

Amino Acid Sequence↗
PubMed1992

Heterogeneity of 3'untranslated region of bovine acidic FGF transcripts.

A bovine aFGF genomic clone (14.2 Kb) has been isolated and characterized. This clone contains exons 2 and 3 interrupted by 6.7 Kb long intron. Exon 3 contains part of the coding region and the 3' untranslated region (3'UTR). Two overlapping cDNA clones specific for this 3'UTR have been isolated from bovine retina cDNA libraries or after amplification of RNA by the RACE technique. Analysis of these clones and RNAse protection assay demonstrate alternative termination of aFGF transcripts giving rise to differently sized 3'UTR of 2.5 Kb and at least 3.9 Kb. The sequence of these long 3'UTR is highly conserved among species (70% identity between human and rat) which suggests an important role for aFGF expression.

Amino Acid Sequence↗
PubMed1992

Visualization of the plasmin receptor on carcinoma cells.

In order to visualize the receptor for plasmin and plasminogen present on human carcinoma cells, SW1116 and MCF7-MF cells were incubated with biotinylated plasminogen or plasmin and fluoresceinated streptavidin, and counterstained with propidium iodide. It was first demonstrated that biotinylation did not alter the binding properties of plasminogen and plasmin, provided that the biotinylation rate was around 2. Specific staining of tumor cells was obtained using these reagents. Images with green fluorescence were clearly visible as grains or contours at the surface of tumor cells. The localization of fluorescent grains was analyzed more precisely using confocal microscopy. The percentage of stained cells varied from one experiment to another between 10 and 60%. In no experiment were all the cells observed to be positive. Mitotic cells were more frequently stained than non-mitotic cells, suggesting a relationship between the presence of plasmin receptors and cell proliferation. This was confirmed by the use of Ki67 monoclonal antibody (MAb), as B-Pg-binding tumor cells generally had their nucleus stained by this antibody. Other images indicated staining of the extracellular matrix. Finally, 2 rat tumor-cell sub-lines of colonic origin (DHD K12 Pro-b and Reg-b) were shown to bind human biotinylated plasminogen, confirming the strong interspecies reactivity of plasmin receptors.

Animals↗
PubMed1992

On the role of global and local visual information in goal-directed walking.

The aim of the present study was to determine what interactions occur between the visual information available to walking subjects in the global optical flow and those of a more local nature relating to the dilation rate of a target on the retina. A goal-directed walking task was used in which thirteen subjects were asked to stop spontaneously as near as possible to a stationary target. The experiment was carried out in a special room, by means of a texture flow generator with which the velocity and direction of the optical flow arising from the ground were varied. Twelve experimental conditions were tested, involving various combinations of target size and texture velocity. The results show that with both of the targets, modifications to the global flow significantly affected the subjects' performances (walking speed and time-to-contact with the target upon braking) in the fast-approaching texture situation, but not in the receding or slowly-approaching situations. The results are discussed as to what they reveal about the visual strategies used by an actively moving observer to anticipate a collision with a stationary target.

Acceleration↗
PubMed1992

Mammographic features of 455 invasive lobular carcinomas.

Of 6,009 cases of breast cancer studied, 455 (7.6%) were invasive lobular carcinoma (ILC); 341 of these (75%) were pure ILC and 114 (25%) were ILC mixed with ductal forms. The mammographic features were compared with those of the 5,554 other breast carcinomas. Pure ILCs were less frequently round (1% vs 11%) and more frequently spicular (28% vs 23%) or with architectural distortion (18% vs 6%) than the other breast carcinomas. Microcalcifications were less common (24% vs 41%) and retraction of the skin (25% vs 21%) and nipple (26% vs 17%) was more common in pure ILC than in the other breast carcinomas. When complementary magnification views were obtained, only 50% were helpful in diagnosis of ILC while 75% were helpful in diagnosis of other breast carcinomas. Malignancy was less frequently diagnosed in ILC (57%) than in the other breast carcinomas (64%). The results were intermediate in the mixed ILC group.

Adult↗
PubMed1992

[Efficacy and tolerance of 2 new percutaneous vena cava filters. A prospective study in 80 patients].

Eighty consecutive patients with an average age of 66.5 +/- 16 years were reviewed 3 and 9 months after implantation of two new percutaneous vena caval filters (Filcard, Cardial) in order to evaluate their efficacy and tolerance. The indications were: a contra-indication to anticoagulants in 19 cases, recurrent pulmonary embolism under anticoagulant therapy in 22 patients, chronic cor pulmonale in 4 patients; finally, in 35 cases, the filter was implanted prophylactically for a "floating" or extensive ilio-caval thrombosis under anticoagulant therapy or in high risk patients: severe cardio-pulmonary failure, malignant disease, massive pulmonary embolism with a contra-indication to fibrinolytic therapy. All implantations were performed by the jugular approach with no local or general complications apart from one pericaval haematoma with a favourable outcome. Cavography and opacification of the renal veins was carried out systematically during implantation. All patients underwent clinical examination, antero-posterior and lateral X rays of the filter, pulmonary scintigraphy, antero-posterior and lateral cavography, a CT scan of the filter, Doppler ultrasonography and rheoplethysmography of the legs 3 months after implantation. At 9 months, clinical examination, abdominal X rays and rheoplethysmography were repeated. There was 100% follow-up at 3 and 9 months. The complications observed at 3 and 9 months were: 5 cases of malposition (6%), 3 recurrent pulmonary emboli (4%), 9 recurrent venous thromboses (13%), 4 vena caval thromboses (5.7%), 7 thrombi caught in the filter (10%), 27 perforations of the vena cava (38%), 3 over 30 degrees tilts of the filter (4%) and 22 migrations (31%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Ewing's sarcoma of bone in adults: an anatomic-clinical study of 30 cases].

The records of 30 adult patients with Ewing's sarcoma (ES) of bone treated between 1980 and 1990 at the Institut Curie were studied retrospectively; the diagnosis was reevaluated by histological and immunohistochemical analysis, using HNK and anti-neuron specific enolase (NSE) antibodies. The immunohistological analysis disclosed a significant staining of neoplastic cells in only few of our cases and is therefore of limited interest in the diagnosis of ES. Three groups of patients have been considered according to their clinical presentation: axial, peripheric and initial metastatic disease. The global prognosis is poor: the survival rate is 70% after a follow-up period of one year, and 23% after three years. The evolution was severe for patients with pelvic localization and/or initial metastatic disease. In contrast, five of six patients who are currently free of disease after a mean follow-up period of 42 months presented initial peripheric lesion. Four of these six patients were treated by a combination of surgical, chemical and radiation therapies.

Adolescent↗
PubMed1992

[Myocardial infarction in young women: apropos of 22 cases. Pathogenic and prognostic approach].

The authors report 22 cases of myocardial infarction documented by selective left ventriculography and coronary angiography in women under 45 years of age. The average age in this series was 36 +/- 6.8 years. Two patient groups were identified: Group I (n = 16) with the cardiovascular risk factor of oral contraception (mean age 33.9 +/- 5 years); and Group II (n = 6) comprising older patients (43.8 +/- 1.8 years) with a high prevalence of other risk factors (hyperlipidaemia, hypertension, diabetes). Myocardial infarction tended to be the inaugural event in Group I (9 out of 16 cases, 56.2%) whereas symptoms of effort angina were commonly observed in Group II (5 out of 6 cases, 83.3%). Coronary angiography showed more severe coronary lesions in Group II (score 1.5) than in Group I (score 0.75) in which isolated, single vessel disease mainly affecting the left anterior descending artery or normal coronary angiography was observed. Thrombolytic therapy was performed in 8 patients: percutaneous transluminal angioplasty was performed in 4 patients in the first month with a primary success in 3 cases. Coronary bypass surgery was performed in 1 case. The outcome during follow-up lasting 44.5 +/- 4.2 months was mainly favourable as 15 of the 20 patients had no secondary complications. Nevertheless, 2 patients died in the hospital period (1 from cardiogenic shock and 1 from complications of transluminal coronary angioplasty), 2 patients died less than 1 year after acute myocardial infarction (1 sudden death, 1 cardiogenic shock). Although oral contraception was withdrawn in all cases, many women continued to smoke.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Right atrial thrombosis and severe pulmonary embolism].

Two cases of severe pulmonary embolism associated with right atrial thrombosis are reported. In the first case, fibrinolytic therapy was administered and was thought to be a causative factor in the death of the patient due to massive pulmonary embolism. In the second case, the patient was referred for surgery and two enormous thrombi were extracted. Unfortunately, the outcome was fatal. These two cases were confronted with the results of the literature. They strongly suggest that echocardiography should be a first-line investigation in severe pulmonary embolism. The detection of right atrial thrombosis modifies the clinical strategy and orientates treatment towards surgical referral when the patient's condition allows it.

Adult↗
PubMed1992

[Soft tissue angiosarcoma in a child. Immunohistochemical and ultrastructural features].

This observation reports the case of a soft tissue tumor occurring in a 11 years-old boy. On standard histologic staining, this tumor corresponded to an undifferentiated sarcoma of high grade of malignancy. Immuno-histochemical features (laminin, vimentin, UEA I and Factor VIII R-ag) and ultrastructural analysis (presence of Weibel-Palade bodies) led us to the diagnosis of angiosarcoma. This tumor is rarely reported in children and its prognosis remains unknown. Soft tissue angiosarcoma must be differentiated from Kaposi's sarcoma, epithelioid hemangioendothelioma, hemangiopericytoma and spindle cell hemangioendothelioma. This case stresses the importance of immunohistochemical and ultra-structural features in the diagnosis of poorly differentiated vascular neoplasms.

Cell Differentiation↗
PubMed1991

Molecular cloning of RI-HB, a heparin binding protein regulated by retinoic acid.

RI-HB is an extracellular heparin binding protein regulated by retinoic acid and essentially expressed during embryogenesis. This study reports the cloning and sequencing of the cDNA that encodes RI-HB. The sequence of RI-HB contains 121 amino acid residues and is very rich in basic amino acids and cysteines. This sequence was compared to those of HBGAM and MK protein, two other heparin binding proteins exhibiting growth and/or neurotrophic activities. Northern blot analysis indicates that RI-HB mRNA is strongly expressed during early chicken embryogenesis and that it is induced by retinoic acid treatment of chicken fibroblasts and myotubes in culture.

Animals↗
PubMed1991

Systolic intra-cavitary gradients following aortic valve replacement: an echo-Doppler study.

Systolic left ventricular flow was studied by pulsed and continuous wave Doppler in 41 patients following aortic valve replacement for severe stenosis (mean valvular area: 0.58 cm2; range 0.3-0.75 cm2). Maximal left ventricular velocities by continuous wave Doppler study, were higher than 2.5 m.s-1 with a sharp peak at end-systole in five patients in basal condition and in four others after amyl nitrite inhalation. Pulsed Doppler study showed that the high velocities started from the apex or mitral papillary muscle level with a marked chamber narrowing at two-dimensional echography. Only one patient had a systolic anterior motion (SAM) of the anterior mitral leaflet with mitral-septal contact. The left ventricular dimensions, as measured by M-mode echography were compared in the various patient groups. High velocities seemed statistically associated with the smaller systolic and diastolic diameters of the left ventricle and outflow tract and the larger relative thickness of the posterior wall. The highest pressure gradients disappeared after correction of hypovolaemia (one patient), clearance of pericardial effusion (one patient), or beta-blocker treatment (three patients). The present study confirms that left intra-ventricular dynamic gradients can occur after clearance of fixed outflow obstruction, for which Doppler examination is a reliable and innocuous diagnostic means. Haemodynamically, this syndrome resembles hypertrophic obstructive cardiomyopathy, but the scarcity of the systolic anterior motion of the mitral leaflets is suggestive of a different mechanism that could be cavity obliteration or mid-ventricular obstruction.

Adult↗
PubMed1991

Visual cues and attention demand in locomotor positioning.

The aim of this study was to determine what visual cues are used to assess the time-to-contact (Tc) with a stationary target during locomotor positioning. For this purpose, we performed an experiment with restricted central visual cues and analysed the attention demand involved in use of visual cues. 11 subjects were asked to walk towards a target surface and stop in front of it. Two target sizes were used: the tau strategy, consisting of assessing Tc from the relative expansion rate of the target during locomotion, was possible only with the larger one. The same task was also performed in a dual-task situation wherein reaction time to auditory stimuli was recorded. Analysis showed that braking was initiated earlier only in the dual-task situation involving the small target. The secondary task reaction time also increased considerably and actually even sooner when the positioning was done on the small target. These results suggest that a strategy other than tau may be used to assess Tc: with this strategy, the braking distance and walking speed are taken into account. Furthermore, different processing levels must have been involved in these two different methods, since the attention demand differed from one positioning task to the other.

Adult↗
PubMed1991

[Spontaneous giant intramural hematoma of the esophagus. Apropos of a case].

Spontaneous esophageal hematoma is rare, occurring in a context of high esophageal pressure with abnormalities of hemostasis in some cases. We report a case involving the whole length of the esophagus with no evidence of any etiologic factor. The value of CT Scan is reviewed comparatively with esophageal barium examination and endoscopy. CT Scan confirms the diagnosis and the absence of true esophageal perforation. The general course monitored by CT scanning is uneventful, even in the case of extensive mucosal lesions. This justifies the nonaggressive attitude advocated by the majority of authors.

Diagnosis, Differential↗
PubMed1991

[Spontaneous giant intramural hematoma of the esophagus. Apropos of a case].

Spontaneous esophageal hematoma is rare, occurring in a context of high esophageal pressure with abnormalities of hemostasis in some cases. We report a case involving the whole length of the esophagus with no evidence of any etiologic factor. The value of CT Scan is reviewed comparatively with esophageal barium examination and endoscopy. CT Scan confirms the diagnosis and the absence of true esophageal perforation. The general course monitored by CT scanning is uneventful, even in the case of extensive mucosal lesions. This justifies the nonaggressive attitude advocated by the majority of authors.

Esophageal Diseases↗
PubMed1991

[Diagnosis of coronary artery disease by thallium 201 myocardial scintigraphy during atrial pacing].

Rapid atrial pacing may reveal myocardial ischemia but the sensitivity for the diagnosis of coronary artery disease is not high enough for routine use. Therefore, the value of atrial pacing coupled with Thallium 201 scintigraphy was evaluated. Sixty-two patients (53 men and 9 women) referred for investigation of angina or chest pain were divided into two groups: a control group of 13 patients (9 men and 4 women, average age: 57.1 years) with insignificant coronary lesions (less than 50%) (N = 5) or normal coronary angiography (N = 8), and a group of 49 patients (44 men and 5 women, average age: 55.5 years) 27 of whom had a history of myocardial infarction (17 posterior, 10 anterior). Coronary angiography showed single vessel disease in 44.9% of cases, double vessel disease in 34.7% and triple vessel disease in 18.4% of cases, and 1 patient with left main stem disease. All 62 patients underwent the same study protocol which comprised: incremental atrial pacing (to the calculated maximal heart rate), Thallium 201 myocardial scintigraphy immediately after pacing and during the redistribution phase, and coronary angiography. The sensitivities of anginal pain (36.7%) and ECG changes during atrial pacing (57.1%) were too low for the diagnosis of myocardial ischemia. On the other hand, Thallium 201 scintigraphy with atrial pacing was more sensitive (87.8%) and specific (84.6%) for coronary artery disease. Stenosis of the left anterior descending artery was diagnosed with a sensitivity of 96.4% and that of the right coronary artery with a sensitivity of 90.9%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗