PubMed Health⌕ Search

Biomedical subjects

H Mertens

Publications and source records attributed to H Mertens.

At least 19 recordsLinked to original sources
PubMed2006

Biweekly pegylated liposomal doxorubicin in patients with relapsed ovarian cancer: results of a multicenter phase-II trial.

BACKGROUND: The obvious benefit of pegylated liposomal doxorubicin (PLD) for tumour control in recurrent ovarian cancer is frequently offset by severe palmar-plantar erythrodysesthesia (PPE). There is evidence that dose reduction from 50 to 40 mg/m(2) reduces the incidence of PPE without compromising cytotoxic activity. We set out to investigate whether biweekly application further improves the therapeutic index of PLD. PATIENTS AND METHODS: Patients with recurrent ovarian cancer after surgery and adjuvant chemotherapy with platinum and taxane compounds were eligible to participate in this multi-institutional phase II study. PLD was administered at a dose of 20 mg/m(2) every two weeks. Eligible patients had ECOG performance status of < or =2, and sufficient organ function. We employed an optimized two-stage design to test the hypothesis that biweekly application of PLD reduces the frequency of grade III and IV PPE from 25% to 10%. Response and survival were addressed descriptively. RESULTS: Between October 2001 and February 2004, 64 patients with median age of 59 (range 38-81) years were recruited onto this trial. We evaluated 553 (median 7, range 1-25) courses of PLD treatment. Most patients were in their third or fourth line of chemotherapy. PPE was noted in 30 patients (47.6%), but only three participants progressed to grade 3 severity (4.7%, 95% confidence interval 1.0-13.1%). Partial response, stable disease, and tumour progression were observed in 5, 13, and 24 patients, respectively. Median overall and progression-free survival were 18.2 (range, 1.4-34.0) and 4.3 (range 0.5-22.3) months. CONCLUSIONS: Biweekly PLD may reduce the incidence of PPE while retaining efficacy in relapsed ovarian cancer. Our data support the need for a randomized trial to strengthen these assumptions.

Adult↗
PubMed2006

[Value of diffusion-weighted imaging for diagnosing vertebral metastases due to prostate cancer in comparison to other primary tumors].

PURPOSE: Several publications have reported that the apparent diffusion coefficient is generally lower in metastatically affected vertebrae. Therefore, metastases are represented in diffusion-weighted images by increased signal intensity in comparison to unaffected vertebrae. However, there were indications that metastases due to prostate cancer may differ from this. Therefore, the contrast behavior of vertebral metastases due to prostate cancer or tumors with another histology are to be systematically studied using diffusion-weighted images. The present study is intended to examine whether the two groups differed and whether possible differences depended on the degree of sclerosis. MATERIALS AND METHOD: In a retrospective study the vertebral metastases of patients with prostate cancer (n = 18) were compared to those of patients with tumors of another histology (n = 20). A steady-state free precession sequence was used for the diffusion-weighted imaging. Additionally, a T1 weighted sequence before and after administration of contrast agent as well as a fat suppressed T2 weighted sequence were performed. The contrast behavior of the metastases was evaluated for all four sequences and was compared to that of the unaffected parts of the vertebra. RESULTS: In 18 patients of the tumor group, the vertebral metastases showed positive contrast in the diffusion-weighted images, and 2 had minimally negative contrast up to - 0.04. In the prostate cancer group, the contrast was positive in 9 patients and negative in 9. 6 of the metastases with negative contrast had an osteoblastic metastasization, 1 had an osteolysis, and 1 had a normal finding in the conventional X-ray image. Between the tumor group and the prostate cancer group, the medians of the contrasts were not significantly different (p = 0.054). CONCLUSION: In general, the metastatically affected vertebrae appear hyperintense in the diffusion-weighted images. This observation is only true for some vertebral metastases due to prostate cancer. The cause for this seems to be the degree of sclerosis of the metastases. Thus, it cannot be generally deduced from the hypointensity in diffusion-weighted images that a lesion is benign.

Bone Marrow↗
PubMed2005

[Comparison of time-oriented cost accounting catalogs to control a department of radiology].

PURPOSE: Within a hospital, the radiology department has taken over the role of a cost center. Cost accounting can be applied to analyze the costs for the performance of services. By assigning the expenditures of resources to the service, the cash value can directly be distributed to the costs of equipment, material and rooms. Time-oriented catalogs of services are predefined to calculate the number of the employees for a radiology department. Using our own survey of time data, we examined whether such catalogs correctly represent the time consumed in a radiology department. Only services relevant for the turnover were compared. MATERIALS AND METHODS: For 96 primary radiological services defined by the score-oriented German fee catalog for physicians (Gebuhrenordnung fur Arzte), a ranking list was made for the annual procedures in descending frequency order. According to the Pareto principle, the 11 services with the highest frequency were chosen and the time consumed for the technical and medical services was collected over a period of 2 months. This survey was compared with the time-oriented catalogs TARMED and EBM 2000plus. RESULTS: The included 11 relevant radiological services represented 80.3 % of the annual procedures of our radiology department. When comparing the technical services between the time-oriented catalogs and our own survey, TARMED gives a better description of the time consumed in 7 of the 11 services and EMB 2000plus in 3 services. When comparing the medical services, TARMED gives a better description of the time consumed in 6 of the 11 services and EBM 2000plus in 4 services. When averaging all the radiological services, TARMED overestimates the current number of physicians necessary for primary reading by a factor of 10.0 % and EBM 2000plus by a factor of 2.6 %. CONCLUSION: As to the time spent on performing the relevant radiological services, TARMED is slightly superior to describe the radiology department of a hospital than EBM 2000plus. For calculating the number of physicians necessary for primary reading, EBM 2000plus is superior to TARMED.

Accounting↗
PubMed2004

[Computer simulation of a clinical magnet resonance tomography scanner for training purposes].

PURPOSE: The idea for this project was born by the necessity to offer medical students an easy approach to the theoretical basics of magnetic resonance imaging. The aim was to simulate the features and functions of such a scanner on a commercially available computer by means of a computer program. MATERIALS AND METHODS: The simulation was programmed in pure Java under the GNU General Public License and is freely available for a commercially available computer with Windows, Macintosh or Linux operating system. The graphic user interface is oriented to a real scanner. In an external program parameter, images for the proton density and the relaxation times T1 and T2 are calculated on the basis of clinical examinations. From this, the image calculation is carried out in the simulation program pixel by pixel on the basis of a pulse sequence chosen and modified by the user. The images can be stored and printed. In addition, it is possible to display and modify k-space images. RESULTS: Seven classes of pulse sequences are implemented and up to 14 relevant sequence parameters, such as repetition time and echo time, can be altered. Aliasing and motion artifacts can be simulated. As the image calculation only takes a few seconds, interactive working is possible. CONCLUSION: The simulation has been used in the university education for more than 1 year, successfully illustrating the dependence of the MR images on the measuring parameters. This should facititate the approach of students to the understanding MR imaging in the future.

Computer Simulation↗
PubMed2001

Contrast-enhanced magnetic resonance angiography of mammary artery grafts after minimally invasive coronary bypass surgery.

BACKGROUND: The aim of the study was to investigate the application of the contrast-enhanced magnetic resonance angiography (CE-MRA) for the visualization of left internal mammary artery (LIMA) bypass. METHODS: A total of 30 patients with LIMA bypass (22 men, 8 women, 35 to 77 years) received a CE-MRA 4 to 20 days after surgery. The non-ECG-triggered CE-MRA was performed during expiration using a body array coil at a 1.5 Tesla scanner (Magnetom-Vision). A three-dimensional gradient-echo sequence with slice interpolation technique was applied. For the three-dimensional visualization, single coronal slices were postprocessed with maximal intensity projection. Of 30 patients 22 agreed to a comparative coronary angiography. RESULTS: Five bypasses were identified up to the end-to-side anastomosis. A total of 80% of the bypass course was detectable in 13 patients and 60% in 11 patients. In two LIMA bypasses only 30% of the proximal part could be viewed; one was found by conventional coronary angiography to be occluded. The other conventional coronary angiography showed the LIMA bypass to be patent. CONCLUSIONS: The complete course of the LIMA bypass to the left anterior descending coronary artery can be visualized by the MRA technique. The most reliable imaging of the distal anastomosis can be realized by reducing the negative influence of the beating heart.

Adult↗
PubMed2000

Percutaneous treatment of acute multiple limb ischemia.

This study evaluates the use of pulse spray pharmacomechanical thrombolysis (PSPMT) in combination with a low dose urokinase infusion and a possible secondary percutaneous treatment in the management of acute multiple limb ischemia. A retrospective analysis of 185 patients treated with PSPMT revealed eight patients with acute simultaneous ischemia of more than 1 limb. Seven patients presented with acute ischemia of both lower limbs; one patient presented with acute ischemia of the left arm and both lower limbs. All patients were treated using a combination of PSPMT and low dose urokinase infusion. The combination of PSPMT and low dose urokinase infusion was completely successful in 6 cases. In 1 patient with bronchogenic carcinoma PSPMT failed and immediate surgical thrombectomy was performed. In the other patient we obtained clot dissolution with thrombolysis in one leg, residual clots at the popliteal level in the other leg however had to be removed by surgical embolectomy. Embolism was the cause of the occlusion in 6 patients. Atherosclerotic disease appeared to be the underlying cause in the other 2 patients. Atherosclerotic disease was treated with balloon angioplasty and stenting. In the 8 patients with multiple limb ischemia, combination of PSPMT, low dose urokinase infusion, and possibly secondary treatment was useful and constituted a valuable alternative to open surgery. Acute occlusion of the abdominal aorta and acute leg ischemia have a high mortality and amputation rate with variable results in treatment. The use of thrombolysis has reduced the necessity of surgery in arterial occlusive disease and simplifies the treatment of native artery occlusion. Especially in patients with long and multi-level occlusions with poor outflow, thrombolysis seems to be the treatment of choice. In our analysis of 8 cases with acute multiple limb ischemia we review our experience with the combination of pulse spray pharmacomechanical thrombolysis (PSPMT), low dose continuous urokinase infusion and a possible subsequent percutaneous treatment of the obstructing lesion. The final purpose was to investigate if this combination is a successful and safe method in the treatment of acute multiple limb ischemia.

Acute Disease↗
PubMed1998

Clofilium in the isolated perfused rabbit heart: a new model to study proarrhythmia induced by class III antiarrhythmic drugs.

OBJECTIVE: The clinical usefulness of class III antiarrhythmic drugs for the treatment of tachyarrhythmias is limited by their potential proarrhythmic effects, mainly torsades-depointes (TdP). The goal of this experimental study was to develop an isolated whole-heart model exhibiting typical characteristics of class III drug-induced ventricular arrhythmias. METHODS: Isolated rabbit hearts were perfused with a Krebs-Henseleit buffer containing 10 microM clofilium and then exposed to a modified Krebs-Henseleit buffer with 2.0 mM K+ and 0.5 mM Mg2+. Hearts subjected to either clofilium alone or modified buffer alone were used as controls. RESULTS: Under clofilium the QT interval increased from 187 +/- 16 to 282 +/- 33 ms. Within 8 to 25 s after the change of the perfusate, ventricular arrhythmias developed in all hearts associated with a further QT prolongation to 380 +/- 73 ms when the first ventricular extrasystole occurred. Simultaneously, the monophasic action potential durations increased relatively more during late repolarization; from 99 +/- 21 to 110 +/- 25 ms (+11%) at 50% repolarization, from 143 +/- 24 to 178 +/- 40 ms (+24%) at 70%, and from 200 +/- 30 to 275 +/- 53 ms (+38%) at 90%. The predominant rhythm was polymorphic with either two alternating or multiple QRS morphologies exhibiting the characteristic features of torsades-depointes. All control hearts stayed in normal sinus rhythm. CONCLUSION: Under the conditions selected, the isolated perfused rabbit heart represents a useful experimental approach to study the proarrhythmic effects of class III agents. This model provides a convenient way to manipulate the ionic and pharmacologic milieu in a preparation conserving the functional anatomy of the whole organ without interference by cardiovascular reflexes. It might be useful for analyzing the conditions favoring and preventing drug-induced torsades-depointes.

Animals↗
PubMed1998

Drug-related torsades de pointes in the isolated rabbit heart: comparison of clofilium, d,l-sotalol, and erythromycin.

Torsades de pointes is a potentially life-threatening form of polymorphic ventricular tachyarrhythmia typically seen in the presence of repolarization-prolonging agents. We investigated this particular form of tachyarrhythmia in the isolated, perfused rabbit heart. The experimental model was designed to reproduce conditions that are clinically known to be associated with an increased propensity to the development of torsades de pointes. The class III agent clofilium (1 microM) and d,l-sotalol (10 microM), as well as the antibiotic erythromycin (30-150 microM) were infused in the presence of either normal (5.88 mM) or low (1.5 mM) potassium concentration in sinus-driven or atrioventricular (AV)-blocked hearts. Ventricular tachyarrhythmias spontaneously emerged in the clofilium-, d,l-sotalol-, and erythromycin-treated AV-blocked hearts. The episodes showed typical features of torsades de pointes found in humans. They developed within 4-12 min after the onset of infusion, were normally nonsustained, and only rarely degenerated into ventricular fibrillation. Electrical stimulation at cycle lengths <600 ms and perfusion with MgSO4 suppressed arrhythmic activity. In the d,l-sotalol- and erythromycin-treated hearts, torsades de pointes occurred only in the presence of hypokalemia and bradycardia, whereas, in the presence of clofilium, bradycardia alone caused torsades de pointes. Monophasic action-potential recordings demonstrated early afterdepolarizations in endocardial and epicardial recordings. Thus the isolated AV-blocked rabbit heart represents a model for studying drug-related torsades de pointes and its mechanism.

Animals↗
PubMed1996

Radiological method for preoperative determination of isometric attachment points of an anterior cruciate ligament graft.

The purpose of this study was to develop a radiological method which would be preoperatively available to help determine the best graft placement (with respect to isometricity as well as absence of graft impingement) for all knees. The radiological method is described in full detail. We also present the most significant experimental work supporting our development. Firstly, we studied the path followed by radio-opaque objects inserted in the mobile tibia around the fixed femur. Secondly, we compared the distances measured between selected femoral and tibial points radiologically (according to our method) and clinically (with a currently available isometer). The main results were: (1) every tibial point considered moves on an arc of a circle centered or a corresponding femoral point. We should then speak of pairs of isometric points instead of a single femoral isometric zone; (2) the more posterior the tibial point, the more anterior and distal the corresponding femoral point and vice versa; (3) the distance variations induced by rotation did not exceed 1.5 to 2.5 mm when measured either radiologically or clinically; (4) on the radiological and clinical measurements, the difference of length variations during flexion was also very small (mean 0.22 mm; SD 1.2 mm). We conclude that this very simple method allows us to find the femoral transition line for every knee (whatever its size, shape or dynamics). It aids preoperative planning in anterior cruciate ligament graft reconstruction.

Anterior Cruciate Ligament↗
PubMed1993

[Treatment of advanced breast cancer in postmenopausal women with droloxifene: results of a double-blind phase II trial for dose determination].

To determine the optimal daily dose of a new antiestrogen, droloxifene, for the treatment of advanced breast cancer, we have conducted a multicenter, randomized, double blind trial. Postmenopausal women with advanced breast cancer, who could not benefit from loco regional therapy, with positive or unknown estrogen or progesterone receptors were entered in this study. Droloxifene was administered in a double blind randomized design, with daily dose of either 20 (group I), 40 (group II) or 100 mg (group III). None of the patients had received previous systemic antitumor therapy, with the exception of adjuvant chemotherapy terminated at least one year before the patient's recruitment. Patients with at least one measurable tumoral lesion were entered into the trial. Three hundred and sixty nine patients have been enrolled, 234 are fully evaluable for efficacy. Objective response rate (CR + PR) is 31.1, 44.6 and 41.9% for the groups I, II and III respectively (P = NS). Time to response has been short: in the three groups, 50% of the responses have been observed within the 2 first months of treatment. Time to disease progression is 6, 8.3 and 6 months respectively for the 20, 40 and 100 mg/day treatment group. Side effects have been moderate and not dose related. Hot flushes and gastro intestinal disorders have been observed most often. This promising new drug deserves further study and randomized comparison versus tamoxifen.

Aged↗
PubMed1992

Uptake kinetics of technetium-99m-methoxyisobutylisonitrile and thallium-201 in adult rat heart endothelial and fibroblast-like cells in comparison to myocytes.

Endothelial and fibroblast-like cells comprise 5%-10% of total cardiac cell volume and are more resistant to hypoxia than cardiomyocytes. However, their role in the uptake of radiotracers used for myocardial perfusion imaging has largely been ignored. Net uptake of 201TI and 99mTc-hexakis-2-methoxyisobutylisonitrile (99mTc-sestamibi) by cultured rat heart endothelial and fibroblast-like cells and quiescent myocytes was examined. Over a 30-min period, endothelial cells continuously accumulated 99mTc-sestamibi. Initial 201TI accumulation paralleled that of 99mTc-sestamibi; however, after 7 min 201TI accumulation plateaued whereas there was continued slow accumulation of 99mTc-sestamibi. Net uptake of the two radiotracers by fibroblast-like cells was similar to that of 201TI by endothelial cells. In the quiescent myocytes, there was an initial accumulation of both tracers with 201TI net uptake quickly reaching a plateau, whereas 99mTc-sestamibi accumulation continued throughout the 30-min period reaching a level 15-fold greater than that for 201TI. Myocyte uptake of 99mTc-sestamibi was approximately eight times greater than by the endothelial cells when expressed either as activity per mg protein or activity per cell volume. Although significant uptake differences exist among the three cell types, the fact that there is uptake by endothelial and fibroblast-like cells should be considered during image interpretation, particularly in situations in which the hypoxia resistant endothelial and fibroblast-like cells might be the remaining healthiest cell types.

Animals↗
PubMed1991

[Effects of a defined infusion of 10% HAES 200/0.5 in the early phase of a septic syndrome on hemodynamic parameters].

In an animal model the hemodynamic effects of three infusions of HES during the early stage of a septic syndrome were examined. In nine pigs with a body weight between 29 and 36 kg a septic syndrome was produced by infusion of E. coli endotoxin. 1, 4 and 7 hours after beginning of the endotoxin infusion 250 ml HES 200/0.5 were infused. After the 1st and 3rd infusion an increase of the cardiac output resulted, which was previously lowered, without changes of the CVP. During normal CO the 2nd infusion shows an increase of CVP and MAP. PWP did not change. The reactions of the hemodynamic parameters can be well explained physiologically. A volume supply at a reduced CO increases the latter without influence of the CVP. Normalized CO before the infusion resulted in a CVP-increase. The PWP is not evaluable under the conditions of an elevated pulmonary resistance, as it exists at the septic syndrome.

Animals↗
PubMed1988

[Diagnosis and incidence of recurrence of chronic tubal secretory otitis media in childhood].

In a comparison of two groups of children undergoing adenoidectomy, the introduction of routine hearing tests revealed 30.8% more patients with secretory otitis media than in a control group in which tests were carried out only if profound hearing loss was suspected. The history and ear examination were insufficient for detection of secretory otitis media. Evaluation of patients not suspected of hearing loss revealed 24.5% more cases of secretory otitis media than by routine hearing tests. In 25.8% the secretory media recurred, requiring paracentesis or insertion of drainage tubes.

Acoustic Impedance Tests↗
PubMed1983

Penbutolol in hypertension, alone and in combination with furosemide. A long-term multicentre study.

Penbutolol is a new, potent and long-acting non-cardioselective beta-adrenergic blocker which has been evaluated in a 6-month open study of patients with moderate essential or renal hypertension. Eighty-two patients entered the study and 69 completed at least 3 months of treatment. Two-thirds of these showed a good response to penbutolol given alone as a single daily dose of either 40 mg or 80 mg. The major reduction in blood pressure occurred within the first 2 weeks of active therapy. This response was maintained for the entire study period. Blood pressure reduction after penbutolol did not correlate wtih the small reduction in heart rate observed. The remaining patients were treated with a combination of penbutolol and furosemide and most had achieved satisfactory control of their blood pressure by the end of the study. Penbutolol was well tolerated and produced no serious adverse effects. Some patients developed gastro-intestinal side-effects at the beginning of treatment which subsequently resolved. One patient with chronic glomerulonephritis showed a marked deterioration in renal function during the study. This may well have been related to disease progression. No other significant changes in biochemical or haematological parameters were observed.

Adult↗
PubMed1983

A new fluid switching flow sorter.

Conventional cell sorters produce potentially hazardous microdroplets containing dyes and radiolabeled compounds commonly used to identify and trace subpopulations of cells. Many of these substances are potential toxins, mutagens, or carcinogens constituting a risk to personal associated with the sorting device. The separation of living cells for continued study of cell growth from an "in air" sample stream includes the risk of contamination with microorganisms altering the following cultures. To avoid those risks, we have constructed a new capsular flow cytometer sorter which consists of a small chamber completely encasing the sorting mechanism. Data acquisition, analysis, and processing are accomplished by using a microcomputer-based pulse height analyser.

Animals↗
PubMed1982

Coliphage BA14: a new relative of phage T7.

Coliphage BA14 was isolated from sewage and shown to be related to phages T7 and T3. It is similar to T3 in that it directs the synthesis of an S-adenosyl-methionine-cleaving enzyme (SAMase) early upon infection. However, it differs from all other known T7-related coliphages by the inability of its RNA polymerase (gene 1 product) to transcribe T7 DNA or T3 DNA. BA14, T7 and T3 also show marked differences in autoradiographic patterns of their gel-electrophoretically separated 35S-labelled intracellular phage proteins, restriction endonuclease HpaI cleavage patterns of their DNAs, and serological specificities of their infectious particles. Other distinctive features became apparent upon simultaneous mixed infection with BA14 and T7 or T3: inability of BA14 to produce genetic recombinants with either T7 or T3; lack of functional complementation between amber mutants of BA14 and T7 or T3; mutual exclusion and depression of the burst size of the mixedly infected cells.

Antigens, Viral↗
PubMed1981

[Selective ultraviolet phototherapy (SUP) for prophylaxis of polymorphous light eruption (author's transl)].

16 patients with polymorphous light eruption were prophylactically treated with selective ultraviolet phototherapy (SUP). Ten patients showed no or only minimal signs of their disease in a following holiday with high sun exposition; 4 patients had the same skin manifestations as in the years before. Indirect evaluation of the therapeutic success had to be performed in two patients, who did not have holidays in this year. Thus SUP may represent a new prophylactic treatment of polymorphous light eruption.

Adult↗