Training of industrial audiometric technicians.
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Audiometry↗
Biomedical subjects
R Maas
Publications and source records attributed to R Maas.
Pre-operative localized in vivo proton spectroscopy in cerebral tumors at 4.0 Tesla--first results.
Sixteen patients with prediagnosed cerebral lesions were studied with stimulated echo localized 1H-spectroscopy at 4 Tesla. Initially, CT cerebral angiography and MR investigation at 1.5 Tesla were performed. After selecting a patient and receiving his agreement the high field examination started with the acquisition of an MR image of the known tumor at 4 Tesla using head or surface coil. 1H-spectroscopy was performed by selectively exciting a cubic volume between 8 to 20 cubic centimeters in the center of the tumor, in one case below 4 ccm (pinealoma). If possible, in a second examination the corresponding opposite side of the brain was studied. The extirpation of the tumor followed during the next days. Macroscopic aspects, histology and grading of the investigated lesions were determined. In some cases, specimens of the tumors were cooled in cooking salt solution and in liquid nitrogen, respectively, in order to perform in vitro proton MRS at 8.4 Tesla. The evaluable in vivo spectra showed good resolution and significant differences between corresponding cerebral areas with and without tumor as well as between different types of tumor histologies like medulloblastoma, astrocytoma and meningeomas. Often a good correspondence between in vivo and in vitro spectroscopy was seen. No clinically relevant side effects or complications were observed during the in vivo high field examination.
Adult↗
In vitro secretion of peptide hormones by the human placenta: I. ACTH.
In order to address the question of autonomy of placental hormone secretion, fresh human term placentae were utilized for the preparation of small tissue fragments. The fragment pool was divided over four parallel chambers in a superfusion apparatus and could thus serve as both control and experiment under identical in vitro conditions. Oxygen consumption was substantial and could be maintained for at least 5 h. Adrenocorticotrophic hormone (ACTH) concentrations in the effluent buffer were estimated by radioimmunoassay and bioassay. Both non-specific (membrane depolarization with 45 mM KCl) and specific (isoproterenol at 10(-7) M) stimulation increased the ACTH secretion from 10 to 20 pg/min/g to 60 to 80 pg/min/g. Propranolol blocked the adrenergic stimulation almost completely, indicating the specificity of the effect. Thus, in terms of in vitro ACTH secretion, the human placenta can be stimulated and therefore does not seem to behave in an autonomous manner.
Adrenocorticotropic Hormone↗
[The prognostic significance of tumor volume in osteosarcoma with neoadjuvant chemotherapy].
In a retrospective analysis on 128 patients from the trials COSS-80, -82, -85 and -86 initial x-ray pictures were evaluated for tumor diameters in three planes and the prognostic meaning on survival was assessed. In a subset of patients (n = 27) the measured values were compared to values obtained by CT-Scan and a good correlation (r = 0.69) was found. Several parameters for tumor size were defined: absolute tumor length (ATL), relative tumor length (RTL, proportion of tumor to the length of the involved bone), absolute tumor volume (ATV, calculated by the ellipsoid formula) and relative tumor volume (RTL, tumor volume referred to the body surface area) and univariate and multivariate survival analysis were performed. Univariate analysis of metastasis free survival (MFS) revealed a high prognostic significance of the ATL, the ATV and the RTV. The RTL in this patient group demonstrated a tendency only toward an inferior prognosis in larger tumors. None of the patients with a ATV < 70 ml (n = 19) and only one of 33 patients with an ATV < 100 ml relapsed. Cox regression analysis was performed including the variables age, sex, site and response (> 90% tumor necrosis) in 84 patients. ATL and RTL do not enter the model, while the response proves its significance as a valid prognostic factor with a p-value of 0.0004. Adding the ATV as the measure of tumor size to the model it enters as the first term (p = 0.0000) followed by the response (p = 0.0002).(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
[Neoadjuvant therapy for localized osteosarcoma of extremities. Results from the Cooperative osteosarcoma study group COSS of 925 patients].
BACKGROUND: Owing to twenty years of multicentric interdisciplinary cooperation, the COSS group has been able to collect data on a large group of osteosarcoma patients treated by neoadjuvant therapy. This paper reviews results achieved in patients with localized extremity tumors. PATIENTS AND METHODS INCLUSION CRITERIA: Registration into a completed neoadjuvant COSS-Study. Histologically confirmed, primary, localized, high-grade, central osteosarcoma of an extremity; age < 40 years; no pretreatment; interval diagnosis to chemotherapy < or = 3 weeks; no severe comorbidity. Chemotherapy: HD-methotrexate +/- doxorubicin +/- cisplatin +/- ifosfamide +/- BCD. Scheduled local therapy: Surgery. RESULTS: 925 evaluable patients from 101 institutions. Median age 15 years, m:f 1.4:1. Primary site: femur 510, tibia 251, humerus 100, fibula 51, other 13. Tumor-size < 1/3 of the involved bone 616, > or = 1/3 304. Definitive surgery in 903/925 cases, 443 limb salvage procedures. Good response (> 90% necrosis) in 469/806 (58.2%) evaluated tumors. Median follow-up for surviving patients: 5.42 years. Actuarial survival after 5 and 10 years: 72.5% (95%-CI 69.3-75.7) and 66.3% (62.5-70.0), relapse-free 62.1% (58.7-65.4) and 59.4% (55.8-63.0). 683/925 alive (601 first remission), 242 deceased (212 tumor progression, 30 other causes). 66.2% (97.3%) of all relapses within 2 (5) years. Prognosis correlates with tumor-size (< vs. > or = 1/3: 69.9% vs. 58.3% at 10 years) and -site (tibia: 74.2%, humerus: 54.5%) and -response (good vs. poor: 78.2% vs. 52.5%) (all p < 0.01). Actuarial 10-year survival by response grading I-VI according to Salzer-Kuntschik 80.9%, 82.8%, 71.1%, 60.7%, 47.7%, 27.3%. COSS-studies with preoperative 4-drug therapy more efficacious than less aggressive protocols. No impact of doxorubicin scheduling (sequential: rapid vs. 48 h-continuous infusion) or cisplatin scheduling (randomized: 5 h vs. 72 h-infusion) on prognosis detected. CONCLUSIONS: Intensive multiagent chemotherapy and delayed surgery for localized extremity osteosarcoma led to excellent oncologic results in the COSS-studies. Tumor-size, -site, and -response as well as the intensity of upfront chemotherapy correlated with outcome. Giving doxorubicin and cisplatin by continuous infusions did not result in discernible prognostic disadvantages.
Adolescent↗
[Stimulant current diagnosis and therapy with pulsed currents].
Thanks to its efficiency and versatility, and the fact that it has none of the frequently negative side-effects of drugs, stimulant-current therapy has become rapidly more important. The use of defined stimulant-current pulses also enables the condition of neuromuscular system to be described accurately in terms of measurements--a valuable diagnostic aid and therapeutic monitoring facility. The method, procedure and criteria for its use, and some special therapies, are described.
Electric Stimulation Therapy↗
Pancreaticoduodenal artery aneurysm--a life-threatening cause of gastrointestinal hemorrhage: case report and review of the literature.
Gastrointestinal bleeding caused by erosion of a pancreaticoduodenal artery aneurysm in patients with pancreatitis is a rare but potentially life threatening disease. In this case report, the successful treatment of a patient bleeding from a ruptured pancreaticoduodenal artery aneurysm is described. A review of the literature of reported cases discusses the value of early angiographic intervention in patients with unexplained gastrointestinal hemorrhage and suspected rupture of an aneurysm.
Adult↗