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Biomedical subjects

R Felix

Publications and source records attributed to R Felix.

At least 127 records · Page 7Linked to original sources
PubMed2001

Localization of a gene (MCUL1) for multiple cutaneous leiomyomata and uterine fibroids to chromosome 1q42.3-q43.

Dominant transmission of multiple uterine and cutaneous smooth-muscle tumors is seen in the disorder multiple leiomyomatosis (ML). We undertook a genomewide screen of 11 families segregating ML and found evidence for linkage to chromosome 1q42.3-q43 (maximum multipoint LOD score 5.40). Haplotype construction and analysis of recombinations permitted the minimal interval containing the locus, which we have designated "MCUL1," to be refined to an approximately 14-cM region flanked by markers D1S517 and D1S2842. Allelic-loss studies of tumors indicated that MCUL1 may act as a tumor suppressor. Identification of MCUL1 should have wide interest, since this gene may harbor low-penetrance variants predisposing to the common form of uterine fibroids and/or may undergo somatic mutation in sporadic leiomyomata.

Chromosome Mapping↗
PubMed2001

Contrast-enhanced color Doppler sonography of uveal melanomas.

PURPOSE: The purpose of our study was to evaluate the use of the galactose microbubble-based contrast agent Levovist in color Doppler sonography of uveal melanomas. We also evaluated the use of the resistance index and pulsatility index in differentiating tumor-associated vessels from normal vessels in patients with uveal melanomas. METHODS: In this prospective study, 40 patients with uveal melanoma were examined with color Doppler sonography before and after the administration of the contrast agent Levovist. The Doppler signals were recorded from both the tumor and the orbit and were evaluated quantitatively and qualitatively. RESULTS: Tumor-associated vessels were detected without contrast enhancement in 36 of 40 patients and with contrast enhancement in 38 of 40 patients. The spectral characteristics of the Doppler signals did not change after the injection of Levovist. There were no differences-qualitative or quantitative-in Doppler signals between normal and tumor-associated vessels. CONCLUSIONS: The injection of Levovist slightly improved the detection of small vessels in uveal melanomas and the orbit but did not help to differentiate between normal vessels and tumoral vessels. The differentiation of a solid tumor from subretinal hemorrhage or effusion was improved.

Adult↗
PubMed2001

[Influence of positron emission tomography on surgical therapy planning in recurrent colorectal cancer].

The advantages of PET are high sensitivity and specificity for the detection of local tumor relapse, especially in comparison with conventional imaging techniques. Furthermore, there is an additional value of FDG-PET for the detection of tumor manifestations associated with a tumor marker (e.g. serum CEA) increase without suspicious findings in other diagnostic procedures. The methodological advantage of a whole-body examination further improves the detectability of distant metastases. Thus, FDG-PET may induce a change in the therapeutic concept in recurrent colorectal cancer in approximately 30% of cases, concerning the indication for surgery as well as the use of multimodal surgical concepts. By means of the metabolic functional approach FDG-PET offers the possibility of therapy monitoring. This enables very early and more specific indication of response to preoperative therapies or of the presence of residual disease after surgical tumor resection or interventional tumor ablation of metastases or recurrences. PET using new tracer molecules demonstrates an additional advantage of the technique regarding the determination of the micromilieu of a tumor (vascularity, proliferation) compared with all other non-invasive diagnostic methods. This opens up new possibilities to optimize surgical therapy planning and prognostic evaluation.

Adult↗
PubMed2001

[Cutting speeds and success of biopsy with different punch biopsy instruments].

PURPOSE: The goal of our investigations was the verification of the relationship between the reachable cutting speed and the biopsy success for different large-core needle biopsy devices in dependence of the cutting depth as well as different kinds of tissue. METHODS: We measured the dynamic cutting properties of five large-core needle devices with moveable outer needles in air and different tissues. An incremental stripe had been attached on to the outer needle and was moved through a photooptical sensor during the cutting phase. For the valuation of the biopsy success we compared the absolute weight respectively the volume of the tissue probes as well as the relative weight in relation to the size of the sample chambers within the inner trocars. RESULTS: A clear correlation between the cutting speed, the tissue properties and the biopsy success had been registered, especially for more solid tissues. CONCLUSIONS: For a successful large-core needle biopsy a cutting speed of 8 to 12 metres per second is essential. To compensate slower needle movements high quality requirements for the surface, geometry and edge have to be fulfilled.

Animals↗
PubMed2001

[Quantitative computerized tomography of bone mineral density of the mandible. Imaging of topographic distribution of bone mineral density in automated segmentation of mandibular structures].

PURPOSE: Confirmation of a new technique for evaluating bone mineral density (BMD). Colored coded imaging of topographical distribution of bone mineral density in the spongy substance. METHOD: For 20 patients, dental CT examinations of the mandible were made in axial slices. Spongy substance and cortical bone pixels were automatically segmented at foramina mentalia level by means of threshold fixation. The segments were separated in areas relevant to implantology. For each region, BMD was measured by means of quantitative computed tomography (QCT). Spongiose substance of 20 mandibles was segmented by using three threshold intervals to image topographical BMD distribution. RESULTS: Cortical bone and spongy substance could be automatically segmented for 20 mandibles. BMD could be measured in each region. The results were comparable with those of other techniques. Three threshold intervals were segmented for 20 mandibles in the spongy substance to depict topographical BMD distribution. CONCLUSIONS: Areas of low BMD can be detected by imaging topographical BMD distribution. This way, subjective rating by the examiner is eliminated.

Adolescent↗
PubMed2001

Excimer laser-assisted recanalisation of femoral arterial stenosis or occlusion caused by the use of Angio-Seal.

The aim of this study was to demonstrate the effect of excimer laser and balloon angioplasty of femoral artery stenosis and occlusion after use of a haemostatic puncture closure device. A haemostatic puncture closure device (Angio-Seal) was used in 6000 patients after diagnostic or therapeutic artery catheterisation. In 34 of those patients symptoms of peripheral artery disease occurred. Sixteen of those 34 cases were transferred to our clinic for excimer laser angioplasty. All 16 patients presented with symptoms of acute peripheral artery disease within 1-14 days: superficial femoral artery (SFA) occlusions (4 cases); superficial femoral artery stenosis (3 cases); high-grade stenosis of the common femoral artery (CFA; 3 cases); high-grade stenosis of CFA; SFA and profund femoral artery (PFA; 3 cases); and occlusions of CFA, SFA and PFA (3 cases). Before any procedure was performed, informed consent was given by the patient, which included the use of the Angio-Seal closure device. Every patient who had to undergo recanalisation procedures gave additional informed consent which especially included the usage of the excimer laser for recanalisation. A measurement of the walking distance, ankle-brachial systolic pressure index (ABI) and diagnostic angiography was performed in 13 cases before and immediate after as well as 3 and 6 months after therapeutic percutaneous transluminal laser angioplasty followed by balloon angioplasty (PTLA/PTA). In 3 patients the risks of PTLA/PTA was considered too high; those patients underwent surgical repair. Angiographic and clinical improvement was achieved in 13 of 13 patients. The mean walking distance increased from 81 to > 400 m. The average ankle-brachial systolic pressure index (ABI) increased from 0.47 to 0.84. One patient developed a dissection of the SFA, and in 1 case a peripheral embolisation was seen. The PTLA/PTA technique is a successful therapeutic option for patients with femoral artery occlusion or high-grade stenosis after Angio-Seal application.

Angioplasty, Balloon, Laser-Assisted↗
PubMed2001

Intraocular metastases: differential diagnosis from uveal melanomas with high-resolution MRI using a surface coil.

Magnetic resonance imaging with dedicated surface coils plays a pivotal role in differential diagnosis and staging of intraocular tumors. The purpose of this study was to establish MRI criteria for the differential diagnosis of uveal melanomas and intraocular metastases. In a prospective study 44 eyes in 36 patients with intraocular metastases and 200 patients with uveal melanomas were investigated with MRI using a 1.5-T scanner and a 5-cm surface coil. Both quantitative and qualitative evaluation of the resulting images was performed. The MR signal intensities typically expected for metastases (slightly hyperintense on non-contrast T1-weighted images and hypointense on T2-weighted images compared to the vitreous body) were seen in only 23.1%. The typical melanoma signal of either moderate or strong hyperintensity on T1-weighted images and hypointensity on T2-weighted images was seen in 69.4% of the proven melanomas. Contrast enhancement was observed in both metastases and melanomas. Morphological differences between metastases and melanomas were detected in tumor size, shape, position, frequency of retinal detachment, and homogeneity of the tumor. Differentiation between intraocular metastases and uveal melanoma is limited by overlap of signal intensities. Some improvement is achieved with morphologic criteria.

Adult↗
PubMed2001

Quantification of morphologic and hemodynamic severity of coarctation of the aorta by magnetic resonance imaging.

OBJECTIVE: As the morpholgic severity of coarctation of the aorta is difficult to assess, especially after previous repair, the value of the technique of multiplanar reconstruction of magnetic resonance imaging data to achieve a 3-dimensional reconstruction of the aortic arch was evaluated and compared to hemodynamic measurements. METHODS AND RESULTS: We performed 30 examinations in 27 patients aged from 6 to 54 years, with a mean of 21 years, by magnetic resonance imaging using a 1.5Tesla scanner with a standard body coil. Measurements of flow across the coarctation were performed using phase shift velocity mapping, and peak velocity was calculated at the site of stenosis. Aortic cross-sectional area before, at, and beyond the stenosis was reconstructed 3-dimensionally to calculate a percentage degree of stenosis. Morphologic severity of stenosis was correlated to invasively assessed hemodynamic gradients and morphologic data from biplane angiography in 23 patients. Among the 30 examinations, 24 patients had been previously treated by either surgery, in 17 patients, or balloon dilation, while 6 had native coarctation. 3-dimensional reconstruction was possible in all and better delineated the anatomy concerning the hemodynamic relevance of stenoses even as compared with biplane angiography. The correlation between severity of narrowing assessed by diameter measurements in the biplane angiography and 2-dimensional magnetic resonance imaging was r = 0.94, and multiplanar reformation with 2-dimensional magnetic resonance imaging was r = 0.87 with a tendency of higher grading with the 3-dimensional technique (p = 0.0001). The correlation of 2-dimensional magnetic resonance imaging with invasively measured hemodynamic gradients was r = 0.67 versus r = 0.74 for the areas assessed by multiplanar reformation, indicating that the hemodynamic relevance of a morphological approach to evaluate the degree of a stenosis should better be assessed 3-dimensionally. CONCLUSIONS: The 3-dimensional reconstruction of the morphologic severity of coarctation offers additional information over conventional imaging especially in patients with kinking, complex geometry, or collaterals, in whom hemodynamic measurements can become unreliable.

Adolescent↗
PubMed2001

Factors affecting hematopoietic recovery after autologous peripheral blood progenitor-cell transplantation in aggressive non-Hodgkin's lymphoma: a prospective study of 123 patients.

PURPOSE: To analyse prognostic factors influencing hematopoietic recovery in patients with aggressive non-Hodgkin's lymphomas prospectively treated with intensive chemotherapy followed by peripheral blood progenitor-cells transplantation. PATIENTS AND METHODS: Untreated patients with at least two unfavorable factors according to the age-adjusted international prognostic index were included in the LNH 93-3 trial. Patients received three cycles of chemotherapy and PBPC were mobilized using filgrastim. On day 60, a BEAM regimen was initiated followed by PBPC rescue. Among the 123 patients analysed, 60 received G-CSF (5 microg/kg/d) after PBPC transplantation at day 1 and 63 did not. RESULTS: Patients received a mean number of 12.4 x 10(6)/kg (1.86-111.5) CD34+ cells. After transplantation, neutrophil counts exceeded 0.5 x 10(9)/l at a median of 12.4 days (7-41 days) and platelet counts exceeded 50 x 10(9)/l at a median of 15.6 days (9-141 days). Platelets recovery > 50 x 10(9)/l was negatively influenced by BM involvement (20 s 14 days; P = 0.04). The number of CD34+ cells infused (> vs < or = 5 x 10(6)/kg) was correlated with faster platelet recovery (18.7 days vs 13.7 days) (P = 0.007). In 26 patients for whom administration of G-CSF was randomized, time to neutrophil recovery was significantly shorter for patients treated with G-CSF: 10 vs 13 days (P = 0.0005). The incidence of grade 3/4 infection, was similar in both groups. CONCLUSION: In the patient population treated with the same first-line regimen, BM involvement and infusion of fewer CD34+ cells delayed platelet recovery. Administration of G-CSF after PBPC significantly reduced neutropenia.

Adolescent↗
PubMed2001

Distinct properties and differential beta subunit regulation of two C-terminal isoforms of the P/Q-type Ca(2+)-channel alpha(1A) subunit.

Two C-terminal splice variants (BI-1 and BI-2, now termed Ca(v)2.1a and Ca(v)2.1b) of the neuronal voltage-gated P/Q-type Ca(2+) channel alpha(1A) pore-forming subunit have been cloned (Mori et al., 1991, Nature, 350, 398-402). BI-1 and BI-2 code for proteins of 2273 and 2424 amino acids, respectively, and differ only by their extreme carboxyl-termini sequences. Here, we show that, in Xenopus oocytes, the two isoforms direct the expression of channels with different properties. Electrophysiological analysis showed that BI-1 and BI-2 have peak Ba(2+) currents (I(Ba)) at a potential of +30 and +20 mV, respectively. The different C-terminal sequence (amino acids 2229-2273) of BI-1 caused a shift in steady-state inactivation by +10 mV and decreased the proportion of fast component of current inactivation twofold. Likewise, the biophysical changes in I(Ba) caused by coexpression of the beta(4) auxiliary subunit were substantially different in BI-1- and BI-2-containing channels in comparison to those induced by beta(3). Several of these differences in beta regulation were abolished by deleting the carboxyl-terminal splicing region. By creating a series of GST fusion proteins, we identified two locations in the C-terminal (Leu2090-Gly2229 for BI-1 and BI-2, and Arg2230-Pro2424 for BI-2 only) that determine the differential interaction of beta(4) with the distinct alpha(1A) isoforms. These interactions appear to favour the binding of beta(4) to the AID site, and also the plasma membrane expression of BI-2. These results demonstrate that the final segment of the C-terminal affects alpha(1A) channel gating, interaction and regulation with/by the beta subunits. The data will have several implications for the understanding of the biophysical effects of many channelopathies in which the carboxyl-termini of alpha(1A) and beta(4) are affected.

Animals↗
PubMed2001

Intraoperative computed tomography with the mobile CT Tomoscan M during surgical treatment of orbital fractures.

Up to now it has only been possible to monitor the alignment of orbital floor fractures postoperatively with a computed tomography (CT) examination with coronal sectioning. If this showed an incorrect positioning, renewed surgery and anaesthetics were often required. The purpose of this study was the implementation and definition of the spectrum of indications for intraoperative CT examinations while keeping patient radiation exposure to a minimum. Thirty-two orbital fracture cases were examined pre- and intraoperatively using the mobile computer tomograph Tomoscan M in coronal sectioning. In this patient collective, 12 cases showed an isolated orbital floor fracture and twenty cases an orbital floor fracture associated with a zygomatic fracture. The technical prerequisite for these examinations was the construction of a suitable radiolucent operating table which permitted coronal sections to be made with the CT-Gantry tilted. The authors aimed to reduce radiation exposure by optimizing the technical setting parameters and closely defining the scan region for the operator. In three of 32 cases there were no surgical indications following clinical and preoperative CT examination. In three of the 20 cases with associated zygomatic fracture a closed reduction with a reduction hook was carried out, and no revision was necessary after the intraoperative CT examination. In 26 cases an open reduction was carried out. Of these open reduced fractures, four had to be revised after intraoperative CT monitoring; one of the isolated orbital floor fractures and three of those associated with a zygomatic fracture. Intraoperative CT monitoring of orbital floor fractures is considered a useful surgical aid. Its advantages are immediate monitoring of the surgical reduction, the presence of the surgeon during scanning enabling him to determine directly the relevant sections to scan, and the resulting radiation exposure.

Adult↗
PubMed2001

[Treatment of arterial traumas by the Wallgraft endoprosthesis].

PURPOSE: Percutaneous peripheral interventional procedures as well as coronary interventions can be complicated by dissections and traumatic lesions of peripheral arteries. The aim of this study was to evaluate the efficacy of treatment for traumatic peripheral arterial lesions. MATERIAL AND METHODS: In this study we used the Wallgraft-Endoprothesis (Boston Scientific, USA), which is a self-expanding covered stent. In 17 patients a total number of 24 endoprostheses (mean length 6.4 cm) were implanted in iliac arteries. Indications for stenting were large dissections (n = 9), arterial perforations (n = 4), aneurysms (n = 3), and stent in stent implantation (n = 2). RESULTS: An immediate exclusion of the lesion could be achieved in all cases. There were no major procedural complications. The primary patency after a mean follow-up of 18 months was 82.4% (14/17). Early reocclusion was seen in two cases, one stent in stent reocclusion and one reocclusion after acute stent thrombosis. In one other case the angiography revealed relevant restenosis (> 75%). The patency could be restored in one of these three cases leading to a secondary patency rate of 94.1%. CONCLUSIONS: The Wallgraft-Endoprotheses seems to be safe and effective to seal large dissections and traumatic lesions of peripheral arteries, showing a high long-term patency rate.

Aneurysm↗
PubMed2001

Anatomical variations in the internal jugular veins of cancer patients affecting central venous access. Anatomical variation of the internal jugular vein.

PURPOSE: Establishing a reliable central venous access is an important procedure in clinical haematology and oncology. The purpose of this study was to determine how anatomical variations in the internal jugular vein (IJV) and its position in relation to the common carotid artery (CCA) in cancer patients affects external landmark puncture. PATIENTS AND METHODS: In 113 patients with haematological or oncological diseases we examined sonographically potential target regions for placement of a central catheter via the IJV. RESULTS: 36% of our patients showed anatomical variations in the IJV and surrounding tissue. CONCLUSIONS: External landmark puncture may be difficult in a considerable number of patients since the IJV might not be situated in the presumed location anteriorly or laterally to the CCA, or a normal lumen may not be present in approximately 1/3 of cancer patients. This study supports the use of ultrasound-guided techniques for central venous catheters particularly in haematological and oncological patients.

Adult↗
PubMed2001

[Laser-induced thermotherapy (LITT). Use of round and pointed laser applicator systems--initial results].

PURPOSE: To assess the advantages and disadvantages by using round and sharp laser application systems during laser-induced thermotherapy. METHOD: 6 in vitro examinations were performed and 12 patients with liver metastases of colorectal carcinoma were treated with laser-induced thermotherapy. All lesions were closely localised to the diaphragm, liver capsule and large intrahepatic vessels. Five patients were treated with the sharp and 7 patients with the round applicator system. After CT-guided insertion of the catheter system into the metastasis laser therapy was performed under MRI control (approx. 25 W, 20 min). RESULTS: Reduction of the distance between the laser applicator and rounded laser catheter tipp (approx. 0.5-1 cm) leads to better placement of the laser applicator in metastases located near the diaphragm, liver capsule and large intrahepatic vessels. Improved therapy results due to complete ablation of metastases were obtained. All patients treated with the round system had complete ablation of metastasis. In 3 of 5 patients treated with the sharp system, MRI control 2 days after therapy showed a residual tumour margin close to the diaphragm or to an intrahepatic vessel. DISCUSSION: Improved ablation can be obtained by closer placement of a round laser catheter in liver metastasis located near the diaphragm, liver capsule and large intrahepatic vessels.

Adult↗
PubMed2001

Magnetic resonance cholangiopancreatography-guided unilateral endoscopic stent placement for Klatskin tumors.

BACKGROUND: Advanced and incurable Klatskin tumors of Bismuth-type III and IV cause obstructive jaundice. Palliation of patients with Klatskin tumors is usually carried out by bilateral endoscopic stent placement. Endoscopic retrograde cholangiography (ERC) in such patients is associated with a comparatively high morbidity and mortality mainly due to postprocedure bacterial cholangitis. To reduce ERC-related complications the outcome of replacing ERC with magnetic resonance cholangiopancreatography (MRCP) was investigated. Subsequently, unilateral contrast injection and stent placement were performed, thus avoiding bilateral contrast injection and stent insertion. METHODS: Patients thought to have a Klatskin tumor underwent clinical evaluation, laboratory, and noninvasive imaging studies before ERC. Patients were enrolled in this feasibility study if investigators agreed with the clinical diagnosis of an advanced and incurable Klatskin tumor. MRCP images were used to determine the predominate ductal drainage for the liver segments thus directing stent placement. Based on these findings, unilateral ERC and subsequent unilateral stent placement were performed. Antibiotics were not given before ERC. Amsterdam-type stents (10F) were placed and replaced routinely at 2 months. In cases of earlier occlusion, the stents were replaced immediately. RESULTS: Thirty-five patients underwent MRCP, ERC, and unilateral stent deployment. Two further patients enrolled after MRCP were withdrawn because ERC could not be carried out. In 35 patients with unilateral stents bilirubin levels decreased (18.9 +/- 6.3 mg/dL to 3.2 +/- 2.3 mg/dL) and jaundice resolved in 86%. After first stent deployment, post-ERC bacterial cholangitis occurred in 6% (2 of 35) of patients. CONCLUSIONS: This new method of MRCP-guided endoscopic unilateral stent placement could reduce ERC-related complications caused by initial stent deployment. The results of this study justify a randomized prospective comparative trial.

Bile Duct Neoplasms↗