Erfahrungen anlässlich des Expertenpanels „Fußball-WM Deutschland – Medical Lessons Learned“, 06.10.2006, München

Ohne Zusammenfassung     

Use of frequency-modulated radiofrequency pulses in MR imaging experiments

With increasing field strength for whole-body MR scanners there is a need for rf pulses of higher bandwidth to perform selective excitation or inversion. AM pulses will have to become shorter thus leading to an enormous requirement for the peak power of the power amplifier. To reduce these requirements the use of frequency modulation is investigated. The effect of pulses based on a linear frequency sweep on the spin system is analyzed by calculation and computer simulation. It turns out that the nonlinear phases induced by those pulses may compensate each other, that therefore spin-echo experiments as usual in MR imaging may be performed, and that the required peak power may be reduced by up to a factor of 50.     

CT scan and threshold vibrometry in the diagnosis of spinocerebellar degenerations

45 patients with spinocerebellar degeneration (SCD) underwent through quantitative investigation of the ventricular and cisternal systems by CT scanning and threshold vibrometry in the limbs to find out whether these parameters could be used for distinguishing mainly spinal from cerebellar forms or from olivopontoce-rebellar atrophy. The increase in the vibration sense threshold and the mild atrophy in the posterior cranial fossa proved typical of spinal forms and the reverse for cerebellar forms. In olivopontocerebellar atrophy enlargement of the cisterns and dilatation of the ventricles always exceeded 85% of normal values.

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Sommario 45 pazienti affetti da degenerazione spinocerebellare (SCD) sono stati sottoposti ad uno studio approfondito di esplorazione quantitativa del sistema ventricolare e cisternale alla TAC e della soglia di percezione vibratoria agli arti per valutare la possibilità di distinguere con questi parametri le forme prevalentemente spinali da quelle cerebellari o delle atrofie olivopontocerebellari. L'aumento della soglia vibratoria e la modesta atrofia in fossa posteriore è risultata tipica delle forme spinali, mentre l'inverso si verifica per le forme cerebellari. Nelle atrofie olivopontocerebellari l'allargamento delle cisterne e la dilatazione dei ventricoli supera quasi sempre l'85% rispetto ai casi normali.

     

Development of cytochrome P-450-altered preneoplastic and neoplastic lesions during nitrosamine-induced hepatocarcinogenesis in the rat

The expression of four cytochrome (cyt.) P-450 isoenzymes has been studied in preneoplastic and neoplastic lesions during the course of nitrosamine-induced hepatocarcinogenesis in the female Wistar rat. Following exposure to diethylnitrosamine (50 or 100 ppm in the drinking water) for 10 days, animals were taken sequentially, and the livers were analyzed for the evolution of adenosine triphosphatase deficient focal lesions. These lesions were subdivided into different phenotypes with regard to their cyt. P-450 isoenzyme expression using serial frozen sections. Our results demonstrate that about 40% of the adenosine triphosphatase-deficient lesions show concomitant alterations in their cyt. P-450 isoenzyme contents. Of these lesions, islets which are characterized by decreased levels of at least three cyt. P-450 isoenzymes show a dramatic increase in their volumetric fraction of liver tissue with progression of time. Although only very few lesions express this phenotype, the contribution to the volumetric fraction of islet tissue raises from about 2% at 10 weeks to about 60% at 35 weeks after cessation of diethylnitrosamine treatment. By contrast, lesions which express less than two alterations in cyt. P-450 isoenzyme levels develop relatively slowly. Similar results were obtained when animals were exposed continuously to diethylnitrosamine for a period of up to 8 weeks. Following treatment of islet-bearing animals with phenobarbital, an induction of cyt. P-450 isoenzymes and NADPH-cyt. P-450-reductase was observed within preneoplastic and neoplastic lesions. This induction was most pronounced in large, expansively growing nodules, a type of lesion which displayed decreased levels of these enzymes in livers of animals not treated with phenobarbital. The elevation of the cyt. P-450 isoenzymes disappeared within 2 to 3 weeks after cessation of inducer treatment. Our results indicate that a high proportion of rapidly growing lesions has assumed a constitutive deficiency in cyt. P-450 isoenzyme expression during nitrosamine-induced hepatocarcinogenesis. This deficiency, however, is not an irreversible quality, since individual cyt. P-450 isoenzymes can be markedly induced by treatment with an enzyme inducer like phenobarbital. Thus, the observed decrease in cyt. P-450 expression during development of malignancy does not result from alterations in the cyt. P-450 encoding structural genes but may rather be related to abnormalities in the function of regulatory systems of a higher order which may play a central role in the maintenance of cell homeostasis.     

Das Verhalten des Knochenmarkes in Krankheiten und die physiologische Function desselben

Ohne ZusammenfassungHierzu Taf. VIII.