Biomedical subjects

R Felix

Publications and source records attributed to R Felix.

At least 37 records · Page 2Linked to original sources

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↗

PubMed2001

CT-guided percutaneous core biopsies of pulmonary lesions. Diagnostic accuracy, complications and therapeutic impact.

PURPOSE: To evaluate the diagnostic accuracy, complications, and therapeutic impact of CT-guided percutaneous core biopsies of pulmonary lesions. MATERIAL AND METHODS: Seventy-nine patients underwent diagnostic CT-guided percutaneous core biopsies of pulmonary lesions between July 1995 and March 1999. Evaluation included corresponding clinical data, pathologic results, and therapeutic consequences. RESULTS: There were 29 benign and 50 malignant lesions. Percutaneous core biopsy had an overall diagnostic accuracy of 95%. For malignant lesions, core biopsy was positive in 48 patients (sensitivity 96%), and for benign lesions, in 27 (sensitivity 93%). There were no false-positive findings. Pneumothoraces were observed in 19 patients (24%) and 4 of them required a chest drain (5%). There were no hematothoraces or major bleeding complications; however, postinterventional local hemorrhages were observed in 23 patients (29%). No hemoptysis was noted. CONCLUSION: Percutaneous core biopsies of pulmonary lesions offer excellent diagnostic accuracy for both benign and malignant pulmonary lesions at a low complication rate.

Adult↗

PubMed2001

Vascularization of malignant and benign skin tumours measured by D-galactose-based signal-enhanced colour Doppler sonography.

PURPOSE: Evaluation of colour Doppler criteria to differentiate between malignant and benign skin tumours on the basis of the degree of vascularization. MATERIAL AND METHODS: The B-mode sonomorphology and the degree of vascularization in colour Doppler of 81 clinically potentially malignant tumours of cutaneous and subcutaneous structures were analyzed and quantified by number of intratumoral vessels per sonographic slice and percentage vessel area. RESULTS: Of all criteria employed, counting the intratumoral vessels visible on one ultrasound slice after application of a signal-enhancing agent led to highest sensitivity (94%) of all used criteria but the specificity was poor (64%). The highest specificity (88%) and greatest diagnostic accuracy (86%) discriminating benign and malignant lesions were found using the criterion "percentage vessel area >5.0%" after all inflamed lesions had been excluded on the basis of clinical criteria. Plain colour Doppler increased the specificity up to 97%, although the sensitivity decreased simultaneously to max. 75%. Analysis of the B-mode morphology and spectral Doppler parameter of intratumoral vessels did not contribute to the differential diagnosis. CONCLUSION: Signal-enhanced colour Doppler sonography is a valuable tool in the pretherapeutic assessment of cutaneous lesions. This method may be relevant for therapy and prognosis.

Adolescent↗

PubMed2001

Detection of myocardial ischemia by electron beam CT. Experimental studies.

PURPOSE: To determine if contrast-enhanced electron beam CT (EBCT) can detect areas of acute myocardial ischemia, and if pharmacological stress testing improves the diagnostic accuracy of EBCT. MATERIAL AND METHODS: We injected 0.5 ml/kg and 1.0 ml/kg b.w. of iopromide at a rate of 4 ml/s into the right atrium of 5 ventilated female minipigs at rest and after occlusion of the left anterior descending (LAD) coronary artery. Both ventricles were examined at six short axis levels with an EBCT unit. Myocardial perfusion was calculated from the time-density curves of four left ventricular myocardial segments and the aorta. We also tested the effect of the contrast agent on myocardial density after i.v. administration of 0.6 mg/kg dipyridamole before and after LAD occlusion. RESULTS: At rest, the contrast agent increased myocardial density by 28+/-2 HU, corresponding to a myocardial perfusion estimate of 67+/-7 ml/min/100 g. After dipyridamole, myocardial density increased by 29+/-4 HU. Following occlusion of the LAD, anteroseptal myocardium displayed 10+/-4 HU density increase. The area of non-enhancement corresponded to ischemic myocardium in stained pathologic sections. CONCLUSION: Contrast-enhanced stress EBCT can be used to detect areas of myocardial ischemia, and EBCT stress perfusion imaging may be necessary to consistently differentiate ischemic from non-ischemic myocardial tissue.

Animals↗

PubMed2001

Stent placement in short unilateral iliac occlusion. Technique and 24-month results.

PURPOSE: To determine the success rate and 24-month follow-up results of primary stent implantation for reconstruction of unilateral short iliac occlusion involving the aortic bifurcation. MATERIAL AND METHODS: In 90 patients attempts of percutaneous transluminal recanalization of a short unilateral occlusion of the iliac arteries were performed. In 72/90 patients, the treatment was successful. Stent implantation was performed after recanalization in all 72 patients. Pre-interventional angiography of successfully treated patients showed unilateral occlusions and contralateral stenosis in 34/72 patients. In 38/72 patients unilateral occlusion without contralateral stenosis was diagnosed. The recanalization of the common iliac artery obstructions were performed with a guidewire and excimer laser angioplasty. Totally 152 stents were used for the treatment of iliac occlusion. Standardized treadmill testing and color-coded Doppler ultrasound were performed before treatment and during the follow-up. RESULTS: In all patients, stents were placed successfully; 5 major and 7 minor complications were observed. A clinical improvement of +2 to +3 according to the American Heart Association criteria was observed in 62 and 10 patients, respectively. Angiographic control was performed after 1-30 months. The primary angiographic patency rate was 83.1%. Angiography revealed significant restenoses in 4 patients successfully treated with transluminal angioplasty, and re-occlusion in 6 patients which were referred to surgery. The patency rate after 24 months was 90.0%. CONCLUSION: Primary stent implantation is an effective treatment for short iliac obstructions and represents a true endovascular alternative to surgery.

Adult↗

PubMed2001

Histopathological correlation to MRI findings during and after laser-induced thermotherapy in a pig pancreas model.

RATIONALE AND OBJECTIVES: To investigate whether percutaneous laser-induced thermotherapy (LITT) with continuous magnetic resonance (MR) monitoring of thermal effects within the pancreas is feasible in a porcine model. METHODS: Laser applicators were placed in the pancreas of 15 female pigs. A temperature-sensitive (thermo--fast low-angle shot) sequence was used for continuous monitoring of thermal effects during LITT at 1.5 T. Follow-up MR images were acquired, the pigs were observed for 7 days, and then a pathological examination was performed after sacrifice. RESULTS: Continuous MR monitoring visualized thermal effects in pancreatic tissue and thermal damage of the spleen (n = 1), the left kidney (n = 1), and peripancreatic fat (n = 4) but missed the thermal damage of the duodenum (n = 2). Thermal-induced lesions (10--32-mm diameter) were clearly visualized on contrast-enhanced T1-weighted images. CONCLUSIONS: Laser-induced thermotherapy of pancreatic tissue was feasible in this porcine model, and online monitoring was practicable. Further studies are necessary to increase the accuracy of online MR imaging of thermal effects.

Amylases↗

PubMed2001

Combined CT pulmonary angiography and venography for diagnosis of pulmonary embolism and deep vein thrombosis: radiation dose.

A major concern about combined pulmonary CT angiography (PCTA) and CT venography (CTV) refers to the additional radiation exposure to the patient. The purpose of this paper is to analyze the organ dose, the effective dose, and the gonadal dose of combined PCTA and CTV. Effective dose and gonadal dose in PCTA and CTV were calculated. Also measured was the organ doses with thermoluminescence dosimeters in six patients who underwent combined PCTA/CTV. The risk from the effective dose and gonadal dose in combined PCTA/CTV is low. Nevertheless, additional CTV increases the gonadal dose by a significant factor and use of this procedure should be limited in younger patients.

Angiography↗

PubMed2001

Survey of conventional and spiral ct doses.

PURPOSE: To investigate the radiation dose for conventional computed tomography (CT) and spiral CT during different CT examinations at various hospitals and practices. MATERIALS AND METHODS: CT dose index with an active length of 15 cm was measured in 16 different types of CT scanners by using ionization chamber dosimetry. Twenty-six holders (one who has legal responsibility under national law for a radiologic installation) operating a total of seven conventional and 20 spiral CT scanners were asked for their standard parameters for various CT examinations. Weighted CT dose index and dose-length product were determined for each examination. RESULTS: For most examinations, the tube current time product was significantly higher for conventional CT than for spiral CT (.002 </= P </=.05). The ratio of section distance to section thickness for conventional CT was significantly lower than the pitch for spiral CT (.001 </= P </=.05). The weighted CT dose index and dose-length product for spiral CT were about half of those for conventional CT. The third quartiles for weighted CT dose index and dose-length product for spiral CT were much lower than those recommended as reference doses. CONCLUSION: CT examinations with conventional CT scanners are often performed with unnecessarily high radiation dose. For the establishment of reference doses, the radiation dose with spiral CT scanners should be taken into account.

Humans↗

PubMed2001

The role of phosphoinositide 3-kinase in spreading osteoclasts induced by colony-stimulating factor-1.

BACKGROUND: Colony-stimulating factor-1 (CSF-1), a growth and survival factor for osteoclasts, stimulates these cells to spread and migrate towards a gradient of CSF-1. This may support the translocation of osteoclasts to new sites on the bone surface to be resorbed. Phosphoinositide 3-kinase (PI 3-K) is a lipid kinase participating in various signal transduction pathways. OBJECTIVE: To investigate the role of PI 3-K in the CSF-1-induced spreading of osteoclasts. METHODS: In isolated rat osteoclasts treated with or without CSF-1, the distribution of PI 3-K and proteins phosphorylated on tyrosine were investigated using immunofluorescence. In murine osteoclast-like cells grown from bone marrow cells co-cultured with osteoblasts, the activation of the PI 3-K by CSF-1 was determined both in vivo and in vitro. In vivo, the enzyme product in the cell was determined after extraction and separation with thin layer chromatography; in vitro, PI 3-K activity was measured in the pellet immunoprecipitated from the cell lysate. RESULTS: Inhibition of PI 3-K blocked the CSF-1-induced spreading of osteoclasts. In spreading osteoclasts, a portion of PI 3-K was translocated to the periphery where proteins phosphorylated on tyrosine appeared simultaneously. In osteoclast-like cells, CSF-1 stimulated PI 3-K activity. This activity could be immunoprecipitated with antibody against phophotyrosine residues. CONCLUSION: PI 3-K participates in the CSF-1-induced spreading of osteoclasts. The activated PI 3-K may induce the reorganization of the cytoskeleton resulting in spreading and migration.

Androstadienes↗

PubMed2001

[MRI in the diagnosis of tumors of the shoulder girdle area].

The aim of the study was to estimate the value of MRI for evaluation tumors of the shoulder girdle. We diagnosed respectively 13 patients with lesions in the shoulder region. The imaging has been done with a "Magnetom SP 63" (Siemens, Erlangen, Germany). The protocol consisted of T1- and T2-based SE-sequences in axial slice orientation, T1-based imaging in coronary respectively in sagittal slice orientation as well as T1-based sequences after application of contrast medium. The evaluation of the tumor expansion within the soft tissue was possible. The exact diagnosis in some individual cases--neurinoma, cyst of the synovia--could be found by MRI. Estimation of the dignity in the case of infiltrative growth was possible in most cases. To assess the exact type of tumor was often difficult. Especially the dignity of the cartilaginous tumors could not be precisely described.

Acromion↗

PubMed2001

[MRI diagnosis of injuries and diseases of peroneal tendons].

Injuries of the peroneus tendons are common and both the athlete and the older population are at risk. MR imaging is a useful technique for revealing injuries of the peroneus tendons as well as showing anatomic factors associated with these lesions. This article reviews clinical factors and MR imaging characteristics of injuries of the peroneus tendons.

Ankle Injuries↗

PubMed2001

[The use of cross-sectional imaging modalities in the diagnosis of heart valve diseases].

Exact visualization of valve morphology seems to be possible with the cross-sectional imaging modalities, magnetic resonance imaging (MRI) and the recently introduced technique of multi-detector computed tomography (MDCT). These techniques are used, if other non-invasive imaging modalities, like echocardiography, fail or provide only insufficient information. This commonly occurs in the assessment of right ventricular valves. Quantification of valve stenosis is possible by calculating valve orifice area, which can be performed with MRI and MDCT. An estimation of the instantaneous peak gradient can only be achieved by MR flow measurements. MR flow measurement is a reliable method to quantify the degree of mild to moderate stenoses. Quantification of valve regurgitation is possible by measurement of the regurgitation fraction with MR flow measurements as well as with MR volumetry/CT volumetry. But only the MR flow measurement is suitable for the quantification of valve regurgitation in patients with multiple valves involved or cardiac shunting. MRI and probably MDCT are the most reliable methods in the evaluation of ventricular volumes and therefore suitable for the follow-up in patients with valvular heart disease, because changes in volumes are important for therapeutic decisions in these patients. The crucial advantages of MRI compared to CT in the diagnostic of valvular heart diseases however are the absence of radiation exposure, the possibility of quantitative evaluation of valves function using flow measurements and the higher temporal resolution as compared to MDCT.

Adolescent↗