Search PubMed⌕ Search

Biomedical subjects

V Nicolas

Publications and source records attributed to V Nicolas.

At least 37 records · Page 2Linked to original sources
PubMed2002

[MRI-based N-staging in esophageal cancer].

PURPOSE: For planning the therapeutic strategies and estimating the prognosis in esophageal cancer, N-staging is very important. To date, MRI still is of minor importance as imaging modality of the mediastinum despite promising developments in the past, like ECG-gating or "averaging" sequences, e. g., LOTA (Long-term averaging), which facilitate mediastinal and thoracic MR-imaging. In a prospective approach, the value of MRI based N-staging was examined with respect to LOTA-sequences. MATERIAL AND METHODS: Within four weeks prior to esophagectomy, standardized MRI of the esophagus was performed in 15 patients (10 squamous-cell-carcinomas and 5 adenocarcinomas) using a 1.5 T whole body scanner. Imaging quality was classified based on depiction of aortic wall or tracheal wall layers. Criteria for malignant infiltration were a diameter of more than 15 mm or a round appearance of a lymph node together with GD-DTPA enhancement. All data were blinded and separately read by two radiologists. The data of the study were compared with those from the pathological workup of the resected specimen. RESULTS: MRI had a sensitivity of 100 % and a specificity of 78 % for lymph node metastases. Due to incomplete depiction of the celiac trunk (M1), nodal metastasis in a non-enlarged node was missed. CONCLUSION: With modern MRI, N-staging is almost as accurate as the gold standard endoscopic ultrasound and should particularly be used in patients not suited for an endoscopic ultrasound examination.

Adenocarcinoma↗
PubMed2002

[Formation of portal venous collaterals after ligation of the portal vein for induction of liver regeneration].

PURPOSE: Unilateral occlusion of the portal vein induces contralateral lobar hypertrophy - in contrast to complete portal vein occlusion which will result in a cavernous transformation. The impact of the formation of collaterals in partial portal vein occlusion is not sufficiently known. The lobar-hypertrophy- phenomenon is in clinical use for several years to induce iatrogenic liver growth to enable extended resections. After portal vein ligation in patients prior to extended hepatic resections, we noticed a perfusion of the formerly occluded side on CT. Using the well-established mini pig model, we were interested whether portal collaterals are formed as cause of the reperfusion. Ex-situ angiograms of the liver were used for the depiction of collaterals. MATERIALS AND METHODS: Using a median laparotomy as access for preparation of the hepatoduodenal ligament, a proximal left portal vein ligation was performed in eight mini pigs under general anesthesia. The total arrest of the portal blood flow (except in segments VI and VII) was documented by duplex ultrasound. After 4 weeks, all pigs were sacrificed and the weight of the ligated liver segments and non-ligated liver segments was measured and compared to a sham group (n = 5). After insertion of a guiding sheath, an ex-situ DSA of the portal vein was acquired. RESULTS: Compared with the sham group, the liver weight increased by 60 % (23 - 99 %, std. dev. 30 %) in segments VI and VII. Atrophy of the ligated segments was signified by a weight loss of 10 % (standard deviation 15 %). The ex-situ angiograms revealed a uniform pattern of collaterals with subsequent complete total recanalization of the formerly occluded portal vein distal from the ligation. The collaterals reduced the portal venous flow rate. CONCLUSION: After portal vein ligation, uniform collateralization results in recanalization of the occluded portal vein. The extent of the collaterals exceeds the known cavernous transformation. The increase in liver volume is not restrained by the formation of collaterals.

Aged↗
PubMed2001

Sectional depiction of the pelvic floor by CT, MR imaging and sheet plastination: computer-aided correlation and 3D model.

The structures of the pelvic floor are clinically important but difficult to assess. To facilitate the understanding of the complicated pelvic floor anatomy on sectional images obtained by CT and MR imaging, and to make the representation more vivid, a computer-aided 3D model was created from a male and a female torso to develop a teaching tool. A male and a female cadaver torso were investigated by means of CT, MR imaging, and serial-section sheet plastination. A 3D reconstruction of the pelvic floor and adjacent structures was performed by fusion of CT and MR imaging data sets with sheet plastination sections. Corresponding sections from all three methods could be compared and visualized in their 3D context. Sheet plastination allows distinction of connective tissue, muscles, and pelvic organs down to a microscopic level. In combination with CT, MR imaging, and sheet plastination a 3D model of the pelvic floor offers a better understanding of the complex pelvic anatomy. This knowledge may be applied in the diagnostic imaging of urinary incontinence or prolapse and prior to prostate surgery.

Anatomy, Cross-Sectional↗
PubMed2001

Flow cytometric analysis of the association between blood group-related proteins and the detergent-insoluble material of K562 cells and erythroid precursors.

The linkage between blood group-related cell surface proteins and the detergent-insoluble material (DIM) was estimated by flow cytometry using a panel of specific monoclonal antibodies (mAbs) as a comparison of the antibody-binding capacity of intact and Triton-X100-treated cells. Studies were performed with K562 cells expressing endogenous or recombinant proteins and with human erythroid progenitors during their proliferation and differentiation in vitro. Glycophorin C (GPC) was found to be Triton-insoluble in both cellular models. When expressed (erythroid progenitors), Band 3 remained Triton-insoluble. Glycophorin A (GPA), however, behaved as Triton-soluble or insoluble according to the absence (K562) or the presence (erythroid progenitors) of Band 3 respectively. Comparison of the cellular models regarding the proteins that compose the Rh complex also indicated that Rh(D), RhAG and CD47 were resistant to Triton extraction in cells lacking Band 3. Similarly, RhAG and CD47 remained predominantly Triton-insoluble in K562 cells and early progenitors before Rh and Band 3 expression. Further analysis showed that the Kell protein was DIM-associated. In contrast, CD99 and DARC (Fy) proteins were not, or were very poorly, DIM-associated. Additionally, the adhesion molecules CD44 and Lu were completely or partially resistant to detergent extraction respectively. Deletion of the Lu cytoplasmic tail or its replacement by the cytoplasmic domain of GPC resulted in significant increase or decrease of the Triton solubility of the transfected proteins respectively. These data suggest that Triton insolubility of Lu results in part from direct attachment of its cytoplasmic tail with the cytoskeleton. We assume that this method should provide a useful tool to map interaction sites localized in the cytoplasmic domain of recombinant transmembrane proteins.

Anion Exchange Protein 1, Erythrocyte↗
PubMed2001

[Native magnetic resonance tomography imaging of the Morris hepatoma (MH-7777A) in the rat].

UNLABELLED: Goal of the study presented was to establish an oncological animal model for implantable and differentiated hepatoma in the rat and to evaluate imaging of the tumor induced using MRI. MATERIAL AND METHODS: 20 male buffalo rats underwent tumor cell implantation of 150,000 MH7777-A cells via laparotomy. After 12 days MRI was performed T1w SE, T2w TSE fs, TIRM) for tumor detection and measurement of size. Immediately there after all rats were killed and macroscopic and histological examination performed. Pathological findings were correlated with MRI. RESULTS: In 5 out of 20 animals no tumor was found. Mean size of the hepatomas in 15 animals was 3.1 mm (+/- 1.7 mm). On MRI 14 out of 15 tumors were detectable. Mean diameter in MRI was 2.7 mm (+/- 1.5 mm; 1-5 mm). T2w TSE was superior for tumor detection compared with the TIRM, while the best anatomic depiction was offered by T1w SE. CONCLUSIONS: The MH7777-A tumor model presents with a rate of 75% even with the small tumor cell amount of 150,000 cells. With MRI using T2 weighted sequences with fat saturation a detection of tumors with diameters of 1 mm is reliably possible in 93% of the cases.

Animals↗
PubMed1999

Nonsurgical reconstruction of thoracic aortic dissection by stent-graft placement.

BACKGROUND: The treatment of thoracic aortic dissection is guided by prognostic and anatomical information. Proximal dissection requires surgery, but the appropriate treatment of distal thoracic aortic dissection has not been determined, because surgery has failed to improve the prognosis. METHODS: We prospectively evaluated the safety and efficacy of elective transluminal endovascular stent-graft insertion in 12 consecutive patients with descending (type B) aortic dissection and compared the results with surgery in 12 matched controls. In all 24 patients, aortic dissection was diagnosed by magnetic resonance angiography. In each group, the dissection involved the aortic arch in 3 patients and the descending thoracic aorta in all 12 patients. With the patient under general anesthesia, either surgical resection was undertaken or a custom-designed endovascular stent-graft was placed by unilateral arteriotomy. RESULTS: Stent-graft placement resulted in no morbidity or mortality, whereas surgery for type B dissection was associated with four deaths (33 percent, P=0.09) and five serious adverse events (42 percent, P=0.04) within 12 months. Transluminal placement of the stent-graft prosthesis was successful in all patients, with no leakage; full expansion of the stents was ensured by balloon inflation at 2 to 3 atm. Sealing of the entry tear was monitored during the procedure by transesophageal ultrasonography and angiography, and thrombosis of the false lumen was confirmed in all 12 patients after a mean of three months by magnetic resonance imaging. There were no deaths or instances of paraplegia, stroke, embolization, side-branch occlusion, or infection in the stent-graft group; nine patients had postimplantation syndrome, with transient elevation of C-reactive protein levels and body temperature plus mild leukocytosis. All the patients who received stent-grafts recovered, as did seven patients who underwent surgery for type B dissection (58 percent) (P=0.04). CONCLUSIONS: These preliminary observations suggest that elective, nonsurgical insertion of an endovascular stent-graft is safe and efficacious in selected patients who have thoracic aortic dissection and for whom surgery is indicated. Endoluminal repair may be useful for interventional reconstruction of thoracic aortic dissection.

Adult↗
PubMed1999

Systemic effects and side effects of interstitial techniques used in liver tissue.

BACKGROUND: Percutaneous ethanol injection (PEI) and cryosurgery are increasingly used for the treatment of liver malignancies. To create a safety margin and to destroy completely diffusely growing tumors, the precise destruction of healthy liver tissue is necessary. Little is known about the effects of operating on this type of tissue. This study evaluated the effects and side effects of PEI and cryosurgery when applied to normal parenchyma of the liver. STUDY DESIGN: Two groups of six minipigs each were treated with either PEI or cryosurgery to create necrosis in the liver. During and after the procedures, vital signs were monitored and necrotic areas were observed by ultrasonography. Standard and immunohistochemistry stains were made from samples of the necrosis, the liver, and the lung. RESULTS: In the PEI group, thromboembolic complications occurred in all animals (fatality rate 50%). Hematogenous spread of hepatocytes was demonstrated by immunohistochemistry and was a cause of pulmonary embolism. In the cryosurgery group, neither specific complications nor signs of cell spillage occurred. Because of an isolating effect of blood perfusion, hepatocytes close to the portal triads were less damaged, vital cells were present in the periphery, and the necroses were smaller than the induced lesions. CONCLUSIONS: The effect of PEI in healthy liver tissue is unpredictable. This makes the creation of a safety margin or the treatment of a diffusely infiltrating tumor impossible. PEI always introduces the risk of hematogenous cell spread. Effects of cryosurgery are less dependent on tissue qualities. In both techniques, the real extent of complete tissue destruction cannot be visualized by ultrasonography.

Animals↗
PubMed1999

Preformulation: effect of moisture content on microcrystalline cellulose (Avicel PH-302) and its consequences on packing performances.

This study evaluates the influence of moisture content on the packing performances of a new grade of microcrystalline cellulose (MCC) (Avicel PH-302) either by classical method or by an unconventional compression technique (constant volume reduction of powder bed). An increase in moisture content decreases the apparent density of the powder bed, resulting from interparticulate friction enhancement. This modification of apparent density seems to be the main effect caused by the presence of humidity, which explains the variations of compression properties, like an increase of powder plasticity generally observed in the experimental conditions.

Cellulose↗
PubMed1998

[Intramural hemorrhage of the thoracic aorta].

PURPOSE: Intramural hemorrhage (IMH) of the aorta is considered to be a possible preliminary stage to dissection. We report on our experience with MRI, CT, and TEE in the diagnosis as well as in the correct evaluation of the extent of an IMH. METHOD: Between 1983 and 1997 a total of 26 patients were examined using MRI (n = 13) and/or contrast enhanced CT (n = 18) or TEE. The validation was effected in 17 cases through intraoperative or postmortem inspection and in the remaining cases either through continuous clinical or radiological monitoring (n = 6) or through the depiction of the results in 2 different imaging procedures (n = 3). RESULTS: The correct diagnosis of an IMH was made on all examined patients with all imaging modalities. In all cases, MRI enabled the correct identification of the affected aortic segments. Using CT the affected descending aorta was overlooked in one out of 15 cases; TEE failed in one out of two cases of intramural hemorrhage in the aortic arch. A false positive diagnosis was made with CT in one out of 9 cases in the ascending aorta, and using sonography, this occurred in two out of 3 cases in the area of the aortic arch. CONCLUSION: According to our experience, magnetic resonance imaging is the most accurate method for the diagnosis of an IMH.

Adult↗
PubMed1998

[Value of MRI, CT and findings in staging of gynecologic malignancies].

PURPOSE: The present study was designed to compare the value of MRI, CT and clinical examination in local tumor staging of gynaecologic malignancies. PATIENTS AND METHODS: 99 patients with clinically suspected carcinoma of the cervix uteri, ovarian carcinoma or tumor recurrence after gynaecologic cancer underwent all three staging modalities. Furthermore CT and MRI were compared in detecting lymph node metastasis and peritoneal implants. RESULTS: MRI was superior to CT and clinical staging in local tumor staging with an accuracy of 77% for cervical carcinoma and of 88% for recurrent tumors, whereas CT achieved an accuracy of 65% and 55% and clinical staging 60% and 63% accuracy for carcinoma of the cervix and recurrent cancer. Especially for local staging of these two tumor entities MRI is very useful. MRI and CT reached comparable results in the detection of ovarian tumors with an accuracy of 73% for MRI and 69% for CI. Both imaging modalities also showed equal results in the detection of lymph node metastasis, so that primary the cost saving use of CT tumor staging for ovarian lesions and lymph node metastasis should be favoured.

Female↗
PubMed1997

[Femoral arteriovenous fistula and transplant malfunction after allogeneic kidney transplantation. A case report].

This case report deals with the clinical history of a 52-year-old woman who suffered from delayed graft function and ischaemic pain after a technically successful renal transplantation. The past history of the patient revealed that coronary catheters had repeatedly been used for investigation and treatment of myocardial infarctions. The clinical investigation reported here revealed a typical auscultatory result with an arteriovenous (AV) fistula in the right upper limb. After performing a digital arterial angiography, an AV fistula between the femoral artery and vein was demonstrated. Operative occlusion of the fistula increased the perfusion of the kidney graft and the right limb. The patient recovered without wound infection and could leave the hospital with the transplanted kidney functioning well. This case report demonstrates that persistence of AV fistulas after angiographic investigations is rare. Operative occlusion of these lesions should be performed before kidney transplantation to avoid steal phenomena and disturbed would healing.

Angiography, Digital Subtraction↗
PubMed1997

Hilar traumatic neuroma after liver transplantation.

We report our first case of symptomatic traumatic neuroma in the liver hilum after orthotopic liver transplantation. Compression of the hepatic artery caused extraluminal obstruction and resulted in perfusion damage to the graft. Moreover, intimal hyperplasia of the hepatic artery was present. Retransplantation was necessary because the hepatic artery was not salvageable. Potential pathophysiological mechanisms for these findings are discussed.

Adult↗
PubMed1997

[CT and supplementary HR-CT of Kaposi's sarcoma of the pulmonary parenchyma--the morphology of the findings and the diagnostic value].

AIM OF THE STUDY: was an analysis of the CT appearances of Kaposi's sarcoma (KS) in the lung and to determine the diagnostic value of CT and supplementary high resolution CT. MATERIALS AND METHOD: 38 AIDS patients with cutaneous and/or mucocutaneous KS were examined by conventional radiography and CT of the chest during a prospective study. RESULTS: Evaluation of the CT appearances in 16 patients with proven pulmonary KS showed a typical pattern consisting of patchy and flame-shaped infiltrates in relation to the bronchovascular bundle these may be combined with non-necrotic confluent shadows surrounded by areas of ground glass opacity, thickened interlobular septa and round foci. In 12 patients the CT appearances were regarded as characteristic and in four as suggestive but not diagnostic. CONCLUSION: Combination of these features in patients with cutaneous or mucocutaneous manifestations but otherwise negative findings of pulmonary infection allows one to make a diagnosis of pulmonary KS with a high degree of certainty and helps to avoid invasive diagnostic procedures.

Adult↗
PubMed1997

[The significance of the arterial vascular supply of segment IV in living liver donation].

PURPOSE: Postoperative CT's in living liver donors were analysed retrospectively to examine whether atrophies of segment IV occur after procurement depending on arterial vascular supply. PATIENTS AND METHODS: Postoperative CT's from 19 living donors were retrospectively analysed. DSA of the upper abdomen had been performed on all donors prior to donation. RESULTS: The pre-operative DSA images demonstrated an arterial vascular supply of segment IV from the right hepatic artery in 10/19 cases, from the left hepatic artery in 7/19 cases and from both, left and right hepatic artery, in 2/19 cases. Atrophies were seen in 3/7 patients in which segment IV was perfused via left hepatic artery, in further two patients with perfusion from the right hepatic artery or from both sides respectively. Clinically only one patient presented with an abscess. CONCLUSIONS: The patterns of vascular supply to segment IV seen in our patients differ from those published by Couinaud. Since only 3/7 patients with an arterial supply from the left hepatic artery developed a segmental atrophy, we conclude that there must be additional, radiologically not identifiable portal venous branches or collaterals from the right portal vein that maintain perfusion of segment IV.

Adult↗
PubMed1997

Prospective randomized study of drainage and resection on non-occlusive segmental portal hypertension in chronic pancreatitis.

BACKGROUND: In chronic pancreatitis, compression of the splenic vein and superior mesenteric vein (SMV) by an inflammatory mass may cause segmental portal hypertension. Drainage and resection are the principles of surgery for chronic pancreatitis. This study was devised to evaluate the effect of drainage and resection on venous splanchnic blood flow in patients with non-occlusive segmental portal hypertension. METHODS: In 14 of 30 patients with chronic pancreatitis predominantly involving the pancreatic head, segmental portal hypertension due to compression of the splenic vein and SMV was detected by means of indirect splenomesentericoportography and Doppler ultrasonography. None of these 14 patients had symptomatic gastric fundic varices. They were allocated randomly to surgical drainage or resection. Median follow-up was 30 (range 12-48) months. RESULTS: In the resection group, mean(s.d.) splenic vein blood flow increased from 316(46) ml/min before operation to 396(57) ml/min at follow-up (P < 0.01). In the drainage group, preoperative splenic vein blood flow (318(37) ml/min) was not increased after operation (322(37) ml/min). Mean(s.d.) SMV flow increased from 292(42) ml/min before operation to 436(64) ml/min at follow-up (P < 0.01) in the resection group. In the drainage group mean(s.d.) SMV blood flow was 296(32) ml/min before operation and 314(34) ml/min at follow-up. No patient developed fundic gastric varices during follow-up. CONCLUSION: In non-occlusive segmental portal hypertension due to chronic pancreatitis, resection, but not drainage, restores normal venous splanchnic blood flow.

Adult↗
PubMed1997

[Computerized tomography of retroperitoneal liposarcoma].

Besides the malignant fibrous histiocytoma, liposarcoma is one of the most common soft-tissue sarcomas seen in adults. They are most often localized in the lower extremity, followed by sarcomas in the retroperitoneal space which differ from the former in clinical appearance, epidemiology, and prognosis. The prognosis is especially dependent on tumor histology which is mainly classified into four subtypes. The aim of the study was to investigate whether there are specific CT-features for each histologic subgroup, by analyzing the examination of 20 patients. The highest percentage in fat and the biggest tumors were seen with well-differentiated liposarcomas (n = 4), whereas myxoid ones (n = 6) showed the sharpest margins. Round-cell (n = 2) and pleomorphic (n = 5) and pleomorphic (n = 5) types showed mainly soft-tissue attenuation and could not be differentiated, either from each other or from other soft-tissue tumors. A clear identification of the histologic subgroup does not seem to be possible.

Adult↗