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Biomedical subjects

W Prager

Publications and source records attributed to W Prager.

At least 19 recordsLinked to original sources
PubMed1999

[The indications for and results of HDR afterloading therapy in diseases of the skin and mucosa with standardized surface applicators (the Leipzig applicator)].

BACKGROUND: In our department we have developed a standardized applicator for HDR brachytherapy of surface lesions, the so called Leipzig-applicator. We have used this method since September 1987, initially with a Decatron remote afterloading machine, but more recently from November 1990 with a microSelectron-HDR. We report about our experience of 10 years. PATIENTS AND METHOD: Since 1987 we treated 520 patients in 3,026 fractions with this method. In most of the cases we irradiated tumors of the skin of the face, but we also treated tumors of the mouth, of the tongue, of the perianal region and the external genitalia. The histological types were in most of the cases squamous cell carcinomas and basal cell carcinomas, but we also treated tumors like Kaposi-sarcomas, melanomas and skin manifestations of lymphomas and solid organ tumors. We also irradiated benign lesions like keloids after excision. We use single doses between 5 and 10 Gy once to twice a week. The isodose distribution was depending of the tissue infiltration of the tumor. The total dose was 30 to 40 Gy. RESULTS: In 91% of the cases we obtained a complete remission of the tumor, in 6% a partial remission. Recurrences appeared in 8% of the patients. In most cases the reason of the recurrence was a lower brachytherapy dose because of a prior radiotherapy. We didn't observe any severe late radiation reaction. CONCLUSION: We consider that our series of patients treated with HDR brachytherapy and a range of standardized applicators demonstrates that this is a successful method of treating surface lesions.

Adult↗
PubMed1995

[The initial results on the radiobiological comparability of continuous LDR irradiation and PDR irradiation using a guinea pig skin animal model].

AIMS: The classic continuous low dose rate (LDR) brachytherapy was very important in such cases with a higher risk of severe especially late radiation reactions. From clinical experiences and radiobiological considerations it is known, that the therapeutic ratio of LDR is higher than HDR. Another way to combine the therapeutic ratio of LDR and the possibility of optimisation is the use of pulse dose rate (PDR) technique. The PDR-technique is a method, which can be compared with continuous LDR-therapy. PDR should have biological effects equivalent to conventional LDR. MATERIAL AND METHODS: We have tried to compare the classic continuous LDR-technique with 2 PDR-regimes by means of the guinea pig skin model. In this test series we involved 20 female animals with an initial weight of 400 to 500 g. We compared radiation reactions of following regimes: 1. Continuous LDR regimen with a cobalt-60 source with an activity of 5.5 mCi 30 Gy in 60 hours. 2. PDR regimen 0.5 Gy hourly, pulse length minimal 10 minutes, 30 Gy in 60 hours with an Ir-192 source with an activity of nearly 40 mCi. 3. PDR-regimen 0.8 Gy hourly with 9 hours night break (10.00 p. m. to 7.00 a. m.). The radiation reaction was controlled by the help of an evaluation table in which the criteria of radiation reaction were classified according to the degree of seriousness. The observation time is now minimal 14 and maximal 24 months. RESULTS: The findings shows a significant coincidence of early and late radiation reactions of the skin fields irradiated with the continuous LDR-technique and fields irradiated with the PDR-technique. There was not a difference of the radiation reactions between PDR-irradiation with and without night break. CONCLUSIONS: Generally it is possible to compare the radiation reactions of PDR-irradiation and the classic continuous LDR-brachytherapy. It is also possible to use a PDR-regimen with a night break of 9 hours. But results must be calculated for each tissue of interest, in our test consequently for guinea pig skin.

Animals↗
PubMed1994

[The methods and results of simultaneous radiochemotherapy with carboplatin in advanced cervical carcinomas].

PURPOSE: The frequency and the poor therapeutic results in advanced cervical cancer establish the demand for effectiveness of treatment. Recent clinical data have shown that simultaneous radiochemotherapy may yield high remission rates in squamous cell carcinomas of other organs. PATIENTS AND METHODS: In our Department of Radiotherapy and Radiooncology of the University of Leipzig we treated since 1.6.1991 17 patients with advanced cancer of the uterine cervix with a simultaneous radiochemotherapy with carboplatin. RESULTS: The rate of complete remission was 76%. Follow-up is available from six to 24 months. Severe or toxic side effects of the treatment we didn't observe. Eight (47%) patients live relapse-free. CONCLUSIONS: In our opinion randomized studies are required to determine: What is better? Simultaneous radiochemotherapy or radiotherapy?

Adolescent↗
PubMed1992

[Radiobiological research to optimize high-dose-rate afterloading therapy with Ir-192 in extragenital tumors].

Since the introduction of the high-dose rate afterloading therapy a higher biological effectivity of this method has been well known in comparison with the low-dose contact therapy. This will practically taken into account by reducing the dose and more fractionating of the total dose. With our test we want: firstly to prove the influence of the therapy break on the duration of the radiation reaction. Secondly we want to prove the influence of the dose rate on the efficiency of the radiation reaction. We have tried to answer the question by the animal model guinea pig skin. We examined early reactions as well late reactions.

Animals↗
PubMed1990

[Examination of the differential hematocrit and the plasma viscosity under the influence of ionizing radiation].

Systematic investigations into the impact of haemorheological parameters through ionizing rays are not available in literature. The main factors influencing the flow capacity of the blood were determined in vitro by using a set of special methods. Even by using high dosages of irradiation (600 R) only those changes in the flow capacity of the blood could be identified which lay in or near the dispersion area of the methods. These investigations carried out in vitro only take into account the immediate effect of the blood and not rheological changes caused by the intact organism after irradiation.

Blood↗
PubMed1989

Effect of beta-adrenergic blockade on the circadian rhythm of myocardial ischemia in ambulatory patients with stable angina.

The antiischemic efficacy of the beta 1-selective blocker Bisoprolol at a dose of 10 mg daily was examined in an open pilot study during steady state. ST-segment analysis was obtained during a 14-day treatment period by means of Holter monitoring in 13 patients with documented stable coronary heart disease (CHD) and an average age of 61 years. beta-Blockade produced a 30% reduction in the frequency of ischemic episodes. There were statistically significant reductions in the mean duration of the ischemic episodes from 19 to 12 min, in the sum of ST-segment deviations in all episodes from 1.35 to 1.0 mV, and in the mean number of ischemic episodes per day from 7 to 5. The intensity of the ischemic episodes (mV x s) was reduced by two-thirds. The circadian distribution of ischemic episodes was linked to the circadian rhythm of heart rate (HR), and the antiischemic effect paralleled the negative chronotropic effect of beta-blockade. beta-Blockade had a greater effect on HR during the day (-20 beats/min) than during the night (-10 beats/min). A possible secondary antiarrhythmic effect was the 80% decrease in ventricular extrasystoles.

Adrenergic beta-Antagonists↗
PubMed1989

[Initial results of high-dose-rate afterloading treatment of tumors in the head and neck region].

First results of high-dose-rate afterloading therapy in the head-neck area are encouraging. The procedure is not very invasive and is suitable especially for older patients, not tolerating much, who can be hardly submitted another therapeutic method. The limited spatial dose distribution allows a careful treatment of the surrounding tissue in spite of the application of high single doses, however limits the size of tumors too, that the afterloading therapy is possible in (max. 2 cm). The method represents an alternative of the much more complicated procedure of the low-dose contact therapy, that affects the patients in a stronger way like interstitial therapy and moulage treatment. No tumor recurrences or metastasis were seen in our patients. Influence of alteration in fractionation rhythm and of application of sources with very high dose capacity will be the subject of further studies.

Aged↗
PubMed1982

[Effectiveness of programme for early detection of recurrence of endometrial carcinoma (author's transl)].

An intensive after-care programme for early detection of recurrence was applied to 340 patients with endometrial carcinoma. This approach proved to be effective by comparison with a control group, since 26 cases of recurrence (7.6 per cent), largely without symptoms, were identified sooner after primary therapy. While only some of the author's efforts for early recurrence detection were translatable into recurrence therapy, they feel that they should continue their after-care programme within justifiable limits. More information on therapeutic results regarding recurrence of endometrial carcinoma is expected to become available in the forthcoming years. Programme effectiveness must be judged by survival result rather than by expenses.

Female↗
PubMed1981

[Effectiveness of programme for early detection of recurrence of cervical carcinoma (author's transl)].

Various diagnostic methods, generally suitable for early diagnosis of carcinoma recurrence, were used in a systematic localised search programme on 799 patients with invasive cervical carcinoma. The practicability of a concept for early detection of recurrence was verified and established by shortening of latency from first manifestation to recurrence and by more frequent detection of recurrent processes even without symptoms. Reported are methods selected from the programme for their suitability for early recurrence detection. These were necessarily restricted to detection of localised recurrence, following radiological or combined treatment, whereas early detection of parametrial and pelvic wall recurrences seemed to be purposeful, too, when preceded exclusively by primary surgical therapy. Rates of survival, following at least one year of recurrence observation, were encouraging and the support of the view that early detection of recurrence might help to improve the chance of healing.

Female↗
PubMed1980

[Early diagnosis of relapses of cervical and endometrial carcinomas (author's transl)].

A systematic screening-programme for tumor recurrence diagnosis was carried out in 773 patients with cervical or endometrial carcinomas. In comparison with two other patient groups in this patients an earlier diagnosis of tumor recurrences was possible and more relapses were detected in the subclinically symptomless phase. Considering the primary therapy a practicable scheme for diagnosis is proposed.

Endometrium↗
PubMed1979

[Abdominal radiation and mechanical ileus (author's transl)].

In 406 cases of mechanical ileus we observed 42 (10,3%) patients who previously underwent abdominal radiation following resection of an abdominal tumour. In 12 of these patients the intestinal obstruction was only caused by adhaesions, no presence of recurring tumour tissue. Because of the high percentage of benign stenoses laparotomy has to be performed in every case to differentiate the cause of obstruction.

Abdominal Neoplasms↗