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Biomedical subjects

V Nicolas

Publications and source records attributed to V Nicolas.

At least 73 records · Page 4Linked to original sources
PubMed1994

[MR angiography of pelvic veins and the inferior vena cava using 0.5 tesla].

The pelvic veins and/or the inferior vena cava were examined in 15 patients with pelvic vein thrombosis or retroperitoneal tumours, using phlebography or cavography and MR angiography. The latter was carried out using 0.5 Tesla with an inflow technique TR/TE 30/8 ms, flip angle 70 degrees). 3-D projection angiograms were obtained from the 2-D angiograms in the coronary plane. Image quality was generally satisfactory and the veins up to the internal iliac could be demonstrated in all cases; below this, the examination was unreliable. Comparison of the methods with reference to information of therapeutic relevance has shown that in two-thirds of all examinations (8/13) MR angiography and phlebography were of equal diagnostic value. In the presence of a renal cell carcinoma, MR angiography was unable to distinguish between thrombosis and infiltration of the vena cava.

Evaluation Studies as Topic↗
PubMed1993

The diagnosis of thoracic aortic dissection by noninvasive imaging procedures.

BACKGROUND AND METHODS: This study was designed to assess the safety and reliability of new noninvasive imaging methods as compared with aortography in the diagnosis of dissection of the thoracic aorta. One hundred ten patients with clinically suspected aortic dissection followed a diagnostic protocol that included transthoracic and transesophageal color-flow Doppler echocardiography (TTE and TEE), contrast-enhanced x-ray computed tomography (CT), and magnetic resonance imaging (MRI). Imaging results were compared in a blinded fashion and validated independently against intraoperative findings in 62 patients, autopsy findings in 7, and the results of contrast angiography in 64. RESULTS: The sensitivities of MRI, TEE and x-ray CT for detecting dissection were similar, at 98.3, 97.7, and 98.3 percent, respectively; TTE had a sensitivity of only 59.3 percent (P < 0.005). The specificities of both TTE (83.0 percent) and TEE (76.9 percent) were lower than those of x-ray CT (87.1 percent) and MRI (97.8 percent; P < 0.05), mainly as a result of false positive findings in the ascending aorta. MRI and x-ray CT were more sensitive than TTE in detecting the formation of thrombus in the entire thoracic aorta (P < 0.05), but were not superior to TEE in this regard. CT was not effective in detecting an entry site or aortic regurgitation, but MRI and TEE accurately identified both. Two patients died during or soon after CT and TEE, and three died between retrograde angiography and surgery. CONCLUSIONS: A noninvasive diagnostic strategy using MRI in all hemodynamically stable patients and TEE in patients who are too unstable to be moved should be considered the optimal approach to detecting dissection of the thoracic aorta. Comprehensive and detailed evaluation can thus be reduced to a single noninvasive diagnostic test in the investigation of suspected dissection of the thoracic aorta.

Adult↗
PubMed1993

[The diagnosis of inflammatory muscular and vascular diseases using MRT with STIR sequences].

The role of MRT in the prebiopsy diagnosis of muscular and vascular inflammatory conditions was evaluated prospectively and an optimal method of examination was investigated. 92 patients with a suspected diagnosis of myositis (60 cases) or vasculitis (32 cases) were examined, in each case two extremities were studied using transverse T1 and T2 weighted SE sequences and double echo STIR sequences on a 0.5 Tesla (56 patients) or 1.5 Tesla magnet (36 patients; T5/S15 Gyroscan, Philips). The site of the biopsy depended on the MRT findings. In 41 patients the suspected diagnosis was confirmed histologically, in two patients an infective myositis was diagnosed on clinical grounds despite negative histology. MRT demonstrated muscle oedema in 86% of patients. There were negative findings after immuno-suppressive therapy (two patients), in focal myositis (3 out of 4 patients) and in one of 7 patients with untreated vasculitis. Amongst 49 patients in whom the suspected diagnosis could not be confirmed there was muscle oedema in 11 cases (9 neuropathies out of 22, two myopathies out of 10). Oedema indicated inflammatory muscular or vascular disease with a sensitivity of 97% (except in treated patients and for focal myositis). The number of false negative biopsies can be greatly reduced by the use of MRT.

Adult↗
PubMed1993

[Indications for spiral-CT in the upper abdomen and the retroperitoneum].

Spiral CT allows the continuous scanning of different organ volumes. This series illustrates our experiences gained with spiral CT technique imaging of the upper abdomen and retroperitoneal space in about 150 patients. The scanning parameters were 120 kvp, 165 mA with a slice thickness of 8 mm and a table speed of 8 mm/s. The total scanning time was 32 s. If required, a non-ionic iodinated contrast medium was administered via a medial cubital vein or the upper mesenteric artery by performing an arterial portography. CT during arterial portography for preoperative detection and localization of focal liver lesions, staging of renal cell carcinoma, and imaging of pancreatic disease are at present the main indications for using the spiral CT technique. Furthermore, it is the method of choice for scanning uncooperative patients.

Humans↗
PubMed1992

[Scapulectomy as an extremity preserving intervention in surgery of soft tissue sarcoma].

In the treatment of soft tissue sarcomas, radical surgery may mean total scapulectomy. If the tumour is localized next to the scapula wide margins can be better achieved by an operation of this kind than by resection of soft parts. In the planning of these operations radical surgery has priority. The functional results after total scapulectomy is acceptable. There is a distinct reduction of shoulder mobility, especially in abduction. As the peripheral joints are fully conserved, the extremity can be used very well in daily life. The indications for total scapulectomy and the technique are discussed with reference to two clinical cases.

Follow-Up Studies↗
PubMed1992

Expression of collagen, osteocalcin, and bone alkaline phosphatase in a mineralizing rat osteoblastic cell culture.

Rat calvaria bone cells isolated by collagenase digestion form a bone-like matrix which mineralizes in vitro in the presence of beta-glycerophosphate, in less than 2 weeks. The purpose of this work was to investigate, in this mineralizing rat osteoblastic cell culture, the synthesis of collagen, osteocalcin, and bone alkaline phosphatase (ALP). The results obtained indicate (1) After 15 days in culture, the extracellular-matrix contains collagen type I, V, and to some extent type III. Metabolic labeling at day 14, during the phase of nodules mineralization as well as new nodules formation, shows that collagen types I and type V are synthesized; (2) During the phase of cell growth, no osteocalcin could be detected in the medium, however, at the point of nodule formation, the osteocalcin level reached values of 3.55 +/- 1.39 ng/ml, followed by a 30-fold increase after nodules became mineralized. At day 14, after metabolic labeling, de novo synthesized osteocalcin was chromatographed on an immunoadsorbing column. With urea-SDS PAGE the apparent molecular weight was determined to be 9,000 daltons. (3) Specific activity of ALP was found to be 10 nmol/min/mg of proteins at cell confluence. At day 15, when nodules are mineralized, this activity was increased by 40-fold. The Michaelis constant was 1.58 10(-3) M/L. ALP was inhibited by L-homoarginine and levamisole but not by L-phenylalanine. ALP was shown to be heat sensitive at 56 degrees C with two slopes of inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1992

Primary melanoma of urinary bladder.

The fourth case of primary melanoma of the bladder is presented together with a review of the previously reported cases and the relevant literature on malignant melanoma in urology. The criteria for classification of the bladder lesion as the primary site are discussed. The eighty-one-year-old female patient was felt not to be suitable for extensive surgery and was successfully treated with a combination of radiation and immunotherapy with recombinant alpha 2 interferon. After previous monthly recurrences of the tumor the patient is in complete remission fifteen months after initiation of therapy. It appears that this form of treatment might be a valuable alternative to radical surgery in elderly patients.

Aged↗
PubMed1992

Magnetic resonance imaging and pulsed Doppler sonography of poststenotic jets: correlation between signal void and flow velocity distribution.

To correlate the appearance of poststenotic jets on gradient echo images with features of localized Doppler spectra of the jets, we studied an in vitro model of steady flow-through stenoses of 86, 96, and 99% area reduction. As fluids, water and a 40% glycerol solution in water were used. MRI was performed with a 1.5 T whole body imager and gradient echo images were obtained in planes parallel to the direction of flow. Doppler spectra were acquired separately from the MR measurements at 1 cm intervals for a distance of 10 cm downstream from the stenosis. Poststenotic signal void was observed for water and for the 40% glycerol solution only if the mean velocity within the stenosis exceeded a limit of 50-60 cm/sec. On the MR images, the jets could be divided into two segments: A proximal jet segment of uniform width equal to the diameter of the stenosis, followed by a distal jet segment which was characterized by broadening and then dissipating signal void. Except for the 99% stenosis, a high signal intensity core was present within the proximal jet segment. In the proximal jet segment, the Doppler measurements showed a low temporal fluctuation of the maximal flow velocity and only little flow opposite to the main flow direction. In the distal jet segment, the velocity fluctuation and the intensity of reverse flow increased sharply. The high signal intensity core of the jet was associated with a poststenotic zone of constant maximal flow velocity. The results demonstrate a close relationship between characteristic features of poststenotic jets in MRI and pulsed Doppler sonography.

Blood Circulation↗
PubMed1992

Diagnosis of thoracic aortic dissection. Magnetic resonance imaging versus transesophageal echocardiography.

BACKGROUND: Aortic dissection requires prompt and reliable diagnosis to reduce the high mortality. The purpose of this study was to assess the reliability of both ECG-triggered magnetic resonance imaging (MRI) and transesophageal two-dimensional echocardiography combined with color-coded Doppler flow imaging (TEE) for the diagnosis of thoracic aortic dissection and associated epiphenomena. METHODS AND RESULTS: Fifty-three consecutive patients with clinically suspected aortic dissection were subjected to a dual noninvasive imaging protocol in random order; imaging results were compared and validated against the independent morphological "gold standard" of intraoperative findings (n = 27), necropsy (n = 7), and/or contrast angiography (n = 53). No serious side effects were encountered with either imaging method. In contrast to a precursory screening transthoracic echogram, the sensitivities of both MRI and TEE were 100% for detecting a dissection of the thoracic aorta irrespective of its location. The specificity of TEE, however, was lower than the specificity of MRI for a dissection (TEE, 68.2% versus MRI, 100%; p less than 0.005), which resulted mainly from false-positive TEE findings confined to the ascending segment of the aorta (TEE, 78.8% versus MRI, 100%; p less than 0.01). In addition, MRI proved to be more sensitive than TEE in detecting the formation of thrombus in the false lumen of both the aortic arch (p less than 0.01) and the descending segment of the aorta (p less than 0.05). There were no discrepancies between the two imaging techniques in detecting the site of entry to a dissection, aortic regurgitation, or pericardial effusion. CONCLUSIONS: Both MRI and TEE are atraumatic, safe, and highly sensitive methods to identify and classify acute and subacute dissections of the entire thoracic aorta. TEE, however, is associated with lower specificity for lesions in the ascending aorta. These results may still favor TEE as a semi-invasive diagnostic procedure after a precursory screening transthoracic echogram in suspected aortic dissection, but they establish MRI as an excellent method to avoid false-positive findings. Anatomic mapping by MRI may emerge as the most comprehensive approach and morphological standard to guide surgical interventions.

Adult↗
PubMed1992

[Superselective interventional angiography].

The authors report on the clinical application of superselective interventional angiography within the framework of revascularisation and occlusion. A coaxial catheter system is used for probing, consisting of an F 5 angiography catheter as guiding catheter and an F 3 catheter as internal catheter. The internal catheter is equipped with a shaft with segments of different flexibility and can take up a guide wire of 0.018" that is sufficiently stable to be rotated and guided. The interplay between the guide wire, which can be manipulated, and the flexible internal catheter enables superselective probing even of peripheral vascular areas. As may be required by the basic disease, the necessary interventional measures can be taken via the superselectively placed microcatheter. Superselective interventional angiography is indicated as an occlusive measure in preoperative vascular occlusion followed by palliative tumour resection, embolisation in haemangioma, chemoembolization in tumours of the liver. Superselective angiography is used for revascularisation in the local lysis of peripheral vessels. Due to the on-target superselective approach, side effects are markedly less than those observed with the interventions performed to date.

Angiography↗
PubMed1992

[Results of CT-controlled puncture of the thorax].

Results of 56 CT-guided biopsies in 45 patients are presented. Aspiration biopsies (n = 23) had a usable result in 75% of the cases; cutting biopsies (n = 33) in 80%. The main complication was the pneumothorax with 9%; in one patient the procedure caused a haemoptoe.

Humans↗
PubMed1992

[Results of CT-guided puncture biopsies in the abdominal and pelvic regions].

Results of 285 abdominal and pelvic CT-monitored biopsies are presented. 81.6% of the histological biopsies (n = 46) were evaluable (39.1% right positive, 43.5% right negative, 4.35% suspect). In 13% no definite findings were made. For the cytologic examinations and those due to an abscess 44.8% led to a right positive diagnosis and 23.8% gave a true negative finding. In 4.2% of the cases a suspect finding was given. 28% of all cytological evaluations were not definite. The complication rate was 1%.

Adolescent↗
PubMed1991

How osteoblasts become osteocytes: a decreasing matrix forming process.

Osteocyte matrix inclusion process was studied in an in vitro woven bone nodule formation model where a large number of osteocytes at different degrees of maturation were examined. This work focused on early stages of osteocyte inclusion. This matrix inclusion occurred without a matrix synthesis inversion by the future osteocyte and with maintenance of close cell contacts with the replacing cell. A passive matrix embedding process related to a decreased activity of the osteoblast-osteocyte cell is proposed as a comprehensive pathway from osteoblast to osteocyte. The formation of the osteocyte is therefore presented as a very coordinated space and time related cell-cell interaction between cells of the three cell pools of the bone.

Animals↗
PubMed1990

Effects of acidic fibroblast growth factor and epidermal growth factor on subconfluent fetal rat calvaria cell cultures: DNA synthesis and alkaline phosphatase activity.

The effects of acidic fibroblast growth factor (aFGF) and epidermal growth factor (EGF) were examined in subconfluent fetal rat calvaria cell cultures, in the presence of 2% serum. Maximal effect of aFGF and EGF on DNA synthesis measured by [3H]thymidine incorporation was observed after 18 h. aFGF stimulated DNA synthesis by 3.5-fold with an ED50 of 0.75 ng/ml while a 2.3-fold EGF stimulation was recorded with an ED50 of 0.067 ng/ml. 5-Bromo-2-deoxyuridine staining showed a higher stimulation of proliferation in the scattered cells than in the cell clusters. An 18 h aFGF or EGF treatment decreased alkaline phosphatase (ALP) activity by 40 and 23%, respectively, as compared with control cultures. This inhibition was more pronounced after 48 h in the presence of the effectors but no modification of the ALP electrophoretic mobility was observed. These data suggest that aFGF is a less potent mitogen than EGF and a higher inhibitor of ALP activity in fetal rat calvaria cell culture.

Alkaline Phosphatase↗
PubMed1990

[A comparison of digital luminescence radiography and the conventional film-screen technic in pulmonary coin lesions--a clinical study].

The aim of this investigation is the evaluation of DLR for the radiological diagnosis of intrapulmonary coin lesions. For this, a DLR system was used which had been specially developed for chest radiography. Early results were unsatisfactory and therefore specific image parameters were developed. The scope for dose reduction was also investigated. Oncology patients were examined by DLR and by our reference system. Results show that DLR is better than conventional images if edge enhancement is carried out, using the specific parameters. The superiority of the optimised digital images is apparent particularly in those portions of the lung that are obscured by the cardiac or diaphragmatic shadows. Because of image noise, a dose reduction of only 28% is possible, compared with our reference system.

Evaluation Studies as Topic↗
PubMed1990

[The diagnostic value of MR tomography following gadolinium-DTPA compared to computed tomography in bladder tumors].

In a prospective study, 58 patients with carcinomas of the bladder were examined by CT and MRI; in 48, gadolinium-DTPA was administered intravenously. MRI provided exact staging in 89%, compared with 80% with CT. There was 13% over-staging with CT and 11% with MRI. MRI, unlike CT did not result in any under-staging. In 36 patients a quotient could be calculated from the signal intensity of the tumour and surrounding soft tissues both before and after the intravenous contrast medium and the increased quotient after contrast administration could be estimated. There was a significant increase in the tumour/muscle quotient with a mean of 72 +/- 22% (minimum 43%, maximum 153%), corresponding to a marked increase of the signal from the tumour when compared with the pre-contrast images. This had the following advantages compared with CT: accurate differentiation between superficial and intramural spread. MRI was better than CT at demonstrating tumours in the roof of the bladder and at the trigone.

Adult↗