Biomedical subjects

T Fassbender

Publications and source records attributed to T Fassbender.

12 recordsLinked to original sources

PubMed2002

Intraindividual comparison of two extracorporeal LDL apheresis methods: lipidfiltration and HELP.

Low density lipoprotein (LDL) apheresis is an effective treatment option for patients with severe hypercholesterolemia not adequately responding to diet and drug therapy. Membrane differential filtration (MDF), synonymous with double filtration plasmapheresis (DFPP), here named Lipidfiltration, and heparin-induced extracorporeal LDL-precipitation (HELP) are two of the five methods available for extracorporeal LDL apheresis. In this prospective investigation 6 patients with severe LDL-hypercholesterolemia and CAD were treated in a cross-over design with Lipidfiltration at two stages of technical development and HELP to compare the efficacy of these two LDL apheresis methods with respect to lowering and modifying plasma lipids and rheologically relevant plasma proteins, especially fibrinogen. In total, 44 LDL apheresis sessions were investigated. In weekly intervals, patients were treated with consecutive LDL apheresis sessions with either Lipidfiltration and HELP, treating identical plasma volumes. In one part of the investigation Lipidfiltration was performed with the novel Lipidfilter EC-50, combined with a newly developed blood and plasma therapy machine allowing optimized plasma heating. The results showed that the reduction rates of LDL-cholesterol, lipoprotein(a) and triglycerides were essentially identical for both methods. Also pretreatment levels of total cholesterol, triglycerides, LDL-cholesterol and HDL-cholesterol were not significantly different in both treatment groups. Both methods lead to a significant reduction of serum lipoproteins, especially for LDL-cholesterol, which was decreased by 61.4% with Lipidfiltration (treated plasma volume: 2998 ml) and 61.3% with HELP (treated plasma volume: 3013 ml). With respect to Lipidfiltration LDL-cholesterol reduction was more efficient with the novel Lipidfilter EC-50. Mean pretreatment HDL cholesterol concentrations remained unchanged. Comparing Cascadeflo AC-1770 with the novel Lipidfilter EC-50 reduction rates of HDL-cholesterol (17.4% versus 6.4%) and total protein (17.9% versus 7.8%) were significantly reduced. Lipidfiltration and HELP both resulted in a reduction of plasma viscosity and hemorheologically relevant plasma proteins, like fibrinogen.

Blood Component Removal↗

PubMed2000

Combined fractionated external beam radiotherapy and low-dose-rate iodine-125 seeds in an experimental tumor system.

BACKGROUND: To quantify the effect of implanted low-dose-rate iodine seeds combined with fractionated external beam radiation on local control rates in an experimental tumor system. MATERIALS AND METHODS: Experiments were done on the rhabdomyosarcoma R1H of the rat transplanted s.c. into the back of male WAG/Raj albino rats. Tumors were irradiated with 200 kVp X-rays with 2 Gy/fraction 5 times weekly. The total dose of the external beam irradiation varied between 60 and 98 Gy for external beam radiotherapy alone and 10 Gy to 82 Gy for combined external beam radiotherapy and iodine seeds. One to 4 iodine seeds with a median activity of 21.05 MBq were permanently implanted 3 days before the start of external radiotherapy or 6 and 7 iodine seeds alone were used. The median tumor volume at the start of treatment was 0.12 cm3. Local tumor control rates were determined and TCD37% values were calculated applying the maximum likelihood method. RESULTS: With increasing number of implanted iodine seeds the TCD37% (of external beam irradiation) decreased. With external beam radiotherapy alone the TCD37% amounted to 103.2 Gy (95% CI, 101.3 to 105.1 Gy) decreasing to (externally applied doses) 69.7 Gy (63.7 to 74.7 Gy) after 1 implanted iodine seed and further to 31.6 Gy (25.6 to 37.6 Gy) after 4 implanted iodine seeds. The effective dose (equivalent to external dose) per iodine seed decreased with increasing number of implanted iodine seeds. One iodine seed gave an effective dose of 33.5 Gy (28.5 to 39.5 Gy) decreasing to 17.9 Gy (16.4 to 19.4 Gy) after 4 iodine seeds. CONCLUSIONS: The combined treatment of tumors with implanted low-dose-rate iodine seeds and external beam irradiation can decrease the total dose of the external beam irradiation and, hence, offer the possibility of considerable dose sparing of normal tissues without compromising local tumor control rates.

Animals↗

PubMed2000

Rheopheresis: rheologic, functional, and structural aspects.

Rheopheresis is a specific application of membrane differential filtration, synonymous with double filtration plasmapheresis for extracorporeal hemorheotherapy, eliminating an exactly defined spectrum of high molecular weight proteins from human plasma (e.g.: fibrinogen, alpha-2-macroglobulin, low-density lipoprotein cholesterol, IgM). This results in the improvement of blood flow and microcirculation initiated by lowering blood and plasma viscosity, and erythrocyte aggregation. In this context, microcirculation stands not only for the patency of small blood vessels, but for the complete interactive network between plasma, blood cells, the vessel wall, and cellular and extracellular compartments of the surrounding tissue. Insufficient tissue oxygenation leads to tissue damage, e.g., a microcirculatory disorder develops, creating acute as well as chronic symptoms. Therefore, impaired microcirculation has a rheologic, functional, and structural dimension with respect to involved organs or tissues. Rheopheresis represents a specific therapeutic approach with an acute rheologic as well as chronic functional and structural effects, which was confirmed in pilot and controlled clinical studies for several organ systems. Data from 2 controlled clinical trials are available for the safe and effective treatment in patients with age-related macular degeneration.

Adolescent↗

PubMed1999

Sensory processing in Parkinson's and Huntington's disease: investigations with 3D H(2)(15)O-PET.

There is conjoining experimental and clinical evidence supporting a fundamental role of the basal ganglia as a sensory analyser engaged in central somatosensory control. This study was aimed at investigating the functional anatomy of sensory processing in two clinical conditions characterized by basal ganglia dysfunction, i.e. Parkinson's and Huntington's disease. Based on previously recorded data of somatosensory evoked potentials, we expected deficient sensory-evoked activation in cortical areas that receive modulatory somatosensory input via the basal ganglia. Eight Parkinson's disease patients, eight Huntington's disease patients and eight healthy controls underwent repetitive H(2)(15)O-PET activation scans during two experimental conditions in random order: (i) continuous unilateral high-frequency vibratory stimulation applied to the immobilized metacarpal joint of the index finger and (ii) rest (no vibratory stimulus). In the control cohort, the activation pattern was lateralized to the side opposite to stimulus presentation, including cortical [primary sensory cortex (S1); secondary sensory cortex (S2)] and subcortical (globus pallidus, ventrolateral thalamus) regional cerebral blood flow (rCBF) increases (P < 0.001). Between-group comparisons (P < 0.01) of vibration-induced rCBF changes between patients and controls revealed differences in central sensory processing: (i) in Parkinson's disease, decreased activation of contralateral sensorimotor (S1/M1) and lateral premotor cortex, contralateral S2, contralateral posterior cingulate, bilateral prefrontal cortex (Brodmann area 10) and contralateral basal ganglia; (ii) in Huntington's disease, decreased activation of contralateral S2, parietal areas 39 and 40, and lingual gyrus, bilateral prefrontal cortex (Brodmann areas 8, 9, 10 and 44), S1 (trend only) and contralateral basal ganglia; (iii) in both clinical conditions relative enhanced activation of ipsilateral sensory cortical areas, notably caudal S1, S2 and insular cortex. Our data show that Parkinson's disease and Huntington's disease, beyond well-established deficits in central motor control, are characterized by abnormal cortical and subcortical activation on passive sensory stimulation. Furthermore, the finding that activation increases in ipsilateral sensory cortical areas may be interpreted as an indication of either altered central focusing and gating of sensory impulses, or enhanced compensatory recruitment of associative sensory areas in the presence of basal ganglia dysfunction. Altered sensory processing is thought to contribute to pertinent motor deficits in both conditions.

Adult↗

PubMed1992

[The hyperfractionated radiotherapy of tumors in the head-neck area].

This paper provides a survey on investigations that deal with the effects of hyperfractionation. The influence of relevant parameters on treatment results is explained. Furthermore, clinically practicable hyperfractionated treatment schedules for therapy of head and neck tumours are proposed. Clinical and experimental reports reveal that with hyperfractionation two strategies can be realised: 1. Late normal tissue reactions can be reduced without changing total dose. In this case local tumour control rate remains unchanged. 2. To enhance tumour control rates a higher total dose can be administered, if late reactions were dose limiting in the reference schedule. In this case a reduced dose per fraction and an appropriately increased total dose will leave late reactions unchanged. Applying two fractions per day the dose per fraction should not exceed 1.4 Gy. Otherwise severe acute reactions could require treatment interruption. A time interval of at least six hours between fractions reduces the risk of acute and late reactions considerably.

Head and Neck Neoplasms↗

PubMed1992

[The experimental brachytherapy of rhabdomyosarcoma R1H in the rat with iodine-125 seeds].

Rhabdomyosarcoma R1H of the rat with a volume of 1.2 cm3 were treated by implanting three to eight iodine-125 seeds (20.4 MBq). While implantation of inactive seeds had no influence on tumour growth, implantation of three or four seeds caused a reduction in tumour growth rate. Local tumour control was achieved in 71 and 80% of the tumours after implantation of seven and eight seeds, respectively.

Animals↗

PubMed1990

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

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

Evaluation Studies as Topic↗

PubMed1990

A simple experimental technique for interstitial iridium-192 high dose-rate afterloading.

A simple experimental technique for interstitial iridium-192 high dose-rate afterloading is described which allows to perform experimental brachytherapy on a rat tumor model. To illustrate the possibilities and limitations of the technique, rhabdomyosarcoma R1H of the rat were subjected to a combined brachy- and teletherapy treatment applying a total dose of 60 Gy in fractions of 2 Gy. The results show that the surgical procedure had no influence on tumor response. However, would healing was considerably disturbed in animals which received afterloading treatment.

Animals↗

PubMed1988

[Te place of radiotherapy in the treatment of local recurrences of rectal cancer].

A retrospective study was conducted on 67 patients irradiated between 1976 and 1983 at the Medical Radiologic Institute of Tübingen for local recurrences of primarily operated carcinomas of the rectum. Generally, a total dose of 50 to 60 Gy was applied partially in form of a rotational therapy with individual doses of 2 Gy each. The irradiation was well tolerated by most of the patients. The troubles which were mostly severe and progressive before radiotherapy could be relieved by the irradiations in 91% of the patients. This palliative effect lasted for twelve months on an average. The prognosis quoad vitam is unfavorable with a median survival time of 21 months and a three-year survival rate of 15%. A clear dependence on the dose was not found for any of these parameters. Our own results are compared to those communicated by other authors. It is shown that better results can only be achieved by re-operation performed in sano.

Adult↗

PubMed1987

[Results of curative high-voltage irradiation of prostatic cancer].

The results of percutaneous irradiation of 111 patients with prostatic carcinomas during the years from 1974 through 1984 are retrospectively analyzed. A 8 MV X-radiation was applied in form of a moving field therapy charging the prostatic bed with a dose of 67.5 Gy in the 90% isodose enclosing the tumor; the regional lymph nodes were exposed to a total dose of 40 to 50 Gy. CT irradiation planning was used since 1976. All patients showing metastases received endocrine treatment or a cytostatic therapy. The corrected probability of a 10 year survival is 88% for a collective of carcinomas mainly limited to the capsula. Local recurrences were found in 2.7% and local recurrences accompanied by formation of metastases in 5.4% of cases. 12% of the patients showed chronic radiogenic side effects. The influence exerted on the survival curves by tumor stage, histological grade as well as other prognostic factors is discussed.

Aged↗

PubMed1987

[High-dose preoperative radiotherapy of primary inoperable oropharyngeal cancer].

Despite the great progress made by tumor therapy in recent years, it has not yet been possible to obtain a decisive improvement in the five-year survival of about 20% and the five-year recurrence-free survival of about 30% of patients suffering from advanced T3 oropharynx carcinomas. A new way to improve the poor prognosis of these patients is only offered by the possibilities of modern radiotherapy with ultrahard X-radiation as well as by the progress of microsurgery. Up to now, the recurrence-free survival of our patient's group suffering from primarily inoperable T3 oropharynx carcinomas has reached 60% (increase of about 40%). This was achieved by preoperative high-dose irradiation and subsequent implantation of myocutaneous skin flaps with the vascular bundle supplying the flap with blood. As is shown by the communications of literature and our own experience, about 80% of all recurrences will appear within the first 24 months after the end of therapy. In our preoperatively high-dose irradiated group, the observation period is meanwhile 48 months, and the recurrence-free survival is still by 40% higher than that of the control groups. Although a new formation of local recurrences cannot be excluded for the further observation time and despite the small number of patients, the rate of recurrence-free patients suffering from tumors of stage T3N+ signifies a most promising therapeutic approach.

Carcinoma, Squamous Cell↗

PubMed1987

[Preoperative short-term irradiation in rectal cancer].

From 1979 through 1983, 78 patients underwent short-term preirradiation before primary operation for rectal carcinoma at the Medical Radiation Institute of Tübingen. A hyperfractionated total dose of 16 Gy was applied within a maximum time of 36 hours in four fractions of 4 Gy each. Surgery was performed at the last irradiation day. The medium observation time of the total group of patients was five years and three months, at least 40 months. The local recurrence rate of all patients followed up is 9% (7/78), for stage Dukes A it is 6% (2/32), for stage Dukes B 0%(0/25), for stage Dukes C 27% (3/11), and for stage Dukes D 20% (2/10). In the group of 68 patients showing no metastases at the moment of surgery, the rate of formation of remote metastases amounts to 21%, in stage Dukes A to 13% (4/32), in stage Dukes B to 24% (6/25), and in stage Dukes C to 36% (4/11). The relapse-free survival during the follow-up period is 66% (45/68), for stage Dukes A 69% (22/32), for stage Dukes B 68% (17/25), and for stage Dukes C 55% (6/11). There were no acute or late radiogenic complications. Compared to publications about cases treated only by surgery, the present preirradiated patient's group shows a considerable lower local recurrence rate and an increased relapse-free survival rate. These improved treatment results are probably due to preoperative irradiation. The incidence of perioperative complications was not increased by preoperative irradiation.

Combined Modality Therapy↗