Cytologische Kriterien der Wirkung von Sanamycin

Zusammenfassung Die cytostatische Wirkung des Sanamycin auf Milz, Thymus und Nebennieren des Kaninchens wurde mit Hilfe einer vergleichenden cyto-histologischen Untersuchungtechnik geprüft, um einen näheren Einblick in die zellspezifischen Angriffspunkte des Medikamentes zu gewinnen. Der Effekt auf die normale Lymphopoese besteht in einer zeitlich begrenzten Abnahme der reifen Lymphocyten zugunsten einer Vermehrung der Lymphoblasten, wobei histologisch eine allgemeine Reduktion der lymphatischen Gewebsanteile in Erscheinung tritt. Das RHS bleibt in diesem Zusammenhang unberührt. Die Nebennieren zeigen nach hohen Sanamycindosen Veränderungen, die einer beträchtlichen Stresswirkung oder einer reversiblen toxischen Schäidgung entsprechen können. Das durch kurzfristige Sensibilisierung stimulierte Zellsubstrat der Antikörperbildung erfährt durch Sanamycingaben eine nachhaltige Depression, während dieser Effekt bei chronisch sensibilisierten Tieren wesentlich geringer ausgeprägt ist. Die tierexperimentell erhobenen Befunde werden im Hinblick auf die therapeutische Sanamycinwirkung bei lymphatischen Systemkrankheiten und die Möglichkeiteiner Beeinflussungakuter Antigen-Antikörperreaktionen diskutiert.Herrn Professor Dr.R. Schoen zum 65. Geburtstag.     

Endometrial and colorectal tumors from patients with hereditary nonpolyposis colon cancer display different patterns of microsatellite instability

The colorectum and uterine endometrium are the two most commonly affected organs in hereditary nonpolyposis colon cancer (HNPCC), but the genetic basis of organ selection is poorly understood. As tumorigenesis in HNPCC is driven by deficient DNA mismatch repair (MMR), we compared its typical consequence, instability at microsatellite sequences, in colorectal and endometrial cancers from patients with identical predisposing mutations in the MMR genes MLH1 or MSH2. Analysis of non-coding (BAT25, BAT26, and BAT40) and coding mononucleotide repeats (MSH6, MSH3, MLH3, BAX, IGF2R, TGF beta RII, and PTEN), as well as MLH1- and MSH2-linked dinucleotide repeats (D3S1611 and CA7) revealed significant differences, both quantitative and qualitative, between the two tumor types. Whereas colorectal cancers displayed a predominant pattern consisting of instability at the BAT loci (in 89% of tumors), TGF beta RII (73%), dinucleotide repeats (70%), MSH3 (43%), and BAX (30%), no such single pattern was discernible in endometrial cancers. Instead, the pattern was more heterogeneous and involved a lower proportion of unstable markers per tumor (mean 0.27 for endometrial cancers versus 0.45 for colorectal cancers, P < 0.001) and shorter allelic shifts for BAT markers (average 5.1 bp for unstable endometrial cancers versus 9.3 bp for colorectal cancers, P < 0.001). Among the individual putative "target" loci, PTEN instability was associated with endometrial cancers and TGF beta RII instability with colon cancers. The different instability profiles in endometrial and colorectal cancers despite identical genetic predisposition underlines organ-specific differences that may be important determinants of the HNPCC tumor spectrum.     

Failure of oocyte maturation: possible mechanisms for oocyte maturation arrest

For human IVF, the patient's ovaries are hormonally stimulated to ensure the collection of fully matured oocytes that are at the metaphase II stage. Only these oocytes can be successfully fertilized either when mixed with sperm or after ICSI. Nevertheless, in some cases immature or maturing oocytes are recovered from follicles. Surprisingly, sometimes these oocytes do not complete maturation when cultured in vitro, for unknown reasons. In this article we discuss some possible mechanisms that may be responsible for those atypical arrests.     

Scalp topography of the spontaneous K-complex and of delta-waves in human sleep

Objective: Together with spindles, K-complexes are well known hallmarks of stage 2 sleep (S2). However, little is known about their topographical distribution in comparison to delta-waves and to K-complexes superimposed by spindles. Patients and methods: In this study, the topographical distribution of spontaneous K-complexes and delta-waves in S2 and delta-waves in stage 4 sleep (S4) in 10 healthy young adults (aged 20 to 35 years, 7 female) was investigated. K-complexes with and without spindles in S2, delta-waves with and without spindles in S2, and delta-waves in S4 distributed all over the night were visually selected. EEG power maps and statistical parametric maps were calculated. Results: Absolute delta power of S2 K-complexes appeared to be significantly higher than of S2 delta-waves and delta power of S4 delta-waves was higher than of S2 delta-waves. In K-complexes and delta-waves, power was found to be highest over medio-frontal regions in the delta frequency band (0.5 - 4.0 Hz) with a second maximum occipitally in delta-waves, no matter whether superimposed by a spindle or not. Conclusion: K-complexes and delta-waves in S2 differ in topographical distribution. Even though in S2 delta-waves have less power, they have a similar topographical distribution in S2 and S4, supporting the hypothesis that delta-waves in S2 further develop towards delta-waves in slow wave sleep. The delta frequency components of K-complexes and delta-waves are unaffected by spindles.     

Three mitochondrial unassigned open reading frames of Podospora anserina represent remnants of a viral-type RNA polymerase gene

The mitochondrial DNA of Podospora anserina is complex, consisting of a characteristic set of genes with a large number of introns and a substantial amount of sequence of unknown function and origin. In addition, as indicated by various types of reorganization, this genome is highly flexible. Here we report the identification of three unassigned mitochondrial open reading frames (ORF P', ORF Q', ORF 11) as remnants of a rearranged viral-type RNA polymerase gene. These ORFs are not transcribed and may be derived from the integration of a linear plasmid of the type recently identified in a mutant of P. anserina.     

In situ X-ray absorption spectroscopy at the K-edge of red phosphorus in polyamide 6,6 during a thermo-oxidative degradation

We present a new method for studying the influence of flame retardants as a function of time and temperature by measuring the X-ray absorption spectra of the corresponding additive. Here, red phosphorus in polyamide 6,6 was investigated at the phosphorus K-edge using synchrotron radiation. The thermo-oxidative degradation of the polymer was simulated by heating the sample up to 300°C. XANES

1 XANES, EXAFS: X-ray absorption spectroscopy investigating the near edge structure or the fine structure of the extended region, respectively.

spectra were monitored during the degradation process at different temperatures and at a constant reaction temperature as a function of time. The degradation reaction was analyzed by comparing the XANES spectra of red phosphorus and orthophosphoric acid, and the reaction was identified as an oxidation of red phosphorus to H₃PO₄. The results so obtained are confirmed by the EXAFS spectra of the additive in the polymer sample recorded before and after the thermo-oxidative degradation process, and by the EXAFS spectra of suitable reference compounds.     

Attenuation of pathological tremors by functional electrical stimulation II: Clinical evaluation

In this study we evaluated a technique for tremor suppression with functional electrical stimulation (FES), the technical details of which were described in the previous paper. Three groups of patients were investigated: those with essential tremor, parkinsonian tremor, and cerebellar tremor associated with multiple sclerosis. In each group, tremor was attenuated by significant amounts (essential tremor: 73%; parkinsonian tremor: 62%; cerebellar tremor: 38%). These attenuations were in good accord with predictions based on the dynamic analyses and filter designs derived in the previous paper. With filters “tuned” to the lower mean tremor frequency encountered in the cerebellar patients, more attenuation was possible in this group as well. We identified some practical limitations in the clinical application of the technique in its present form. The most important was that in daily use, only one antagonist pair of muscles can realistically be controlled. At first sight, this restricts the usefulness of the system to patients with single-joint tremors. However, the concomitant use of mechanical orthoses may broaden the scope of application.     

Über die jahreszeitlich bedingten änderungen der Empfindlichkeit der Froschlunge gegenüber Acetylcholin

Zusammenfassung Die Empfindlichkeit des Froschlungenpräparates, das im Winter auf Acetylcholinkonzentrationen von 110¹⁶ und darunter anspricht, nimmt in den Sommermonaten um mehrere Zehnerpotenzen ab. Da für die Verwertung des Präparates zur Bestimmung derartig kleiner A.Ch.-Konzentrationen die genaue Kenntnis dieser Empfindlichkeitsänderung notwendig ist, wurde die Umstellung des Präparates während der Monate September und Oktober durch tägliche Versuche verfolgt. Es zeigte sich, daß die Umstellung im September beginnt, besonders rasch in der zweiten Oktoberhälfte fortschreitet und Ende Oktober bereits beendet ist. Dabei steigt die Kontraktionshöhe bei der A.Ch.-Konzentration 110⁴ auf das Doppelte, bei 110¹² auf das Zehnfache. Die Konzentration 110¹⁶, die im Sommer keine sichtbare Wirkung hatte, bewirkt noch eine Verkürzung der Lungen um fast 10%. Auch die Verhältniszahlen, d. h. das Verhältnis der Kontraktionshöhe einer A.Ch.-Konzentration 110^x zur Kontraktionshöhe auf einen Prüfreiz 110⁴, die im Sommer recht niedrig lagen, wuchsen stetig an. Die ursprüngliche Größe und Konstanz der Verhältniszahlen ist im letzten Drittel des Oktober wieder erreicht.