P. Kaden

DNA synthesis during the life cycle of L cells: Morphological, histochemical and biochemical investigations with arabinosylcytosine and thioarabinosylcytosine☆

Abstract DNA-synthesis during the life cycle of L cells: Morphological, histochemical and biochemical investigations with ARA-C and thio-ARA-C. Both ARA-C and thio-ARA-C effect a rapid decrease in the mitotic index of L-cells. At the same time giant cells are formed. Volumetric and planimetric measurements show that this is due to equal accumulation of substances in the cyoplasm and in the nucleus. Cytophotometrically the effects of both cytostatics are characterized by selective killing of S and accumulation of G 1 -phase cells. Also a small accumulation of G 2 -phase cells is seen, suggesting a block between G 2 and mitosis. The giant cells are charaterized by their DNA content as G 1 -phase cells but contain increased masses of RNA (25%) and proteins (300%) . It is shown that one of the enzymes involved indeoxycytidine metabolism (dCMP-deaminase) is greatly enhanced by ARA-C both in randomly and synchronously dividing cells. Simultaneously a shift from soluble to particulate conformation is observed in DNA-polymerase activities. On the basis of these observations combined with earlier investigations on thymidine-kinase and CDP-reductase, a theory for the action of high and low concentrations of ARA-C and thio-ARA-C is proposed.

Effect of bleomycin on the fine structure of mouse fibroblasts.

Asynchronously dividing mouse fibroblasts (L-cells) treated with the antitumor antibiotic Bleomycin show various rather specific morphological alterations. Many of the cells exposed to bleomycin assume a more or less epitheloid cell shape and are larger than untreated cells; in addition to an increase in nuclear size these cells often contain multiple nuclei. In most of the cells nuclei show an almost complete loss of peripheral condensed chromatin. The nucleolar hypertrophy initially observed is followed by a shrinkage and segregation of the nucleolar components. The cytoplasmic alterations include dilatation of the cisternae of the rough endoplasmic reticulum as well as an increase of free, non membrane attached ribosomes, often arranged in spiral- and rosette-shaped polysemes; they are not specific for bleomycin. Asynchron wachsende Mäusefibroblasten (L-Zellen) ändern unter der Einwirkung von Bleomycin ihre typische Zellform. In den vergrößerten, teilweise epitheloiden Zellen finden sich häufig multiple Zellkerne; die Nucleolen sind vergrößert. Eine langdauernde Bleomycin-Behandlung führt hingegen zu einer Verkleinerung der Nucleolen, die häufig mit einer Segregation der nucleolären Bausteine einhergeht. Die auffallendsten ultrastrukturellen Veränderungen bestehen in einem nahezu vollständigen Verlust besonders des kondensierten randständigen Kernchromatins, in einer starken Erweiterung der Cysternen des rauhen endoplasmatischen Reticulums sowie in einer Zunahme der freien, nicht membrangebunden Ribosomen.

Characterization of a Nutritive Synchrony in L-cells

Summary A synchronization method in L-cells producing nutritive stagnation of the cells in G 1 is presented. After reinnoculation, cells proceed through the cycle in the normal 24 hours. The method has the advantage that no chemical blockers are added to the system and a large number of cells is obtained. In a comparison with other synchronizing systems, this system rates in the foreground. Desynchronization due to individual cell physiologies makes investigations of G 2 difficult with this system. The method is uncomplicated and probably applicable to similar cell types.

Vergleich der Bioverträglichkeit von Polypropylen und Polystyrol

S y n t h e t i s c h e P o l y m e r e , K u n s t s t o f f e , w e r d e n i n a l l e n B e r e i c h e n d e r H u m a n m e d i z i n e ingese tz t , z .B . a l s K a t h e t e r . V o n b e s o n d e r e m In te res se s i n d d i e M a t e r i a l i e n , d i e i n d e n m e n s c h l i c h e n K ö r p e r i m p l a n t i e r t w e r d e n u n d dort ü b e r J a h r e v e r w e i l e n , z .B. e i n e Endoprothese . D e r G e s a m t v o r g a n g w i r d u n t e r d e m B e g r i f f B i o v e r t r ä g l i c h k e i t z u s a m m e n g e f a ß t . De r Be g r i f f B i o v e r t r ä g l i c h k e i t bzw. B i o k o m p a t i b i l i t y ist j edoch so u m f a s s e n d , daß es notw e n d i g i s t , den B e g r i f f zu d e f i n i e r e n p 11E r l ä ß t s i c h u n t e r t e i l e n i n e i n e R e a k t i o n d e s Gewebes u n d i n M a t e r i a l V e r ä n d e r u n g e n . Die G e w e b s r e a k t i o n i s t d i e A n t w o r t des l e b e n d e n Systems a u f d i e A n w e s e n h e i t e i n e s F r e m d k ö r p e r s . D i e M a t e r i a l r e a k t i o n i s t d i e W i r k u n g d e r b i o l o g i s c h e n U m g e b u n g a u f d e n F r e m d k ö r p e r . I n d e r v o r g e l e g t e n A r b e i t w i r d d i e R e a k t i o n d e r G e w e b e k u l t u r u n d d e s G e w e b e v e r b a n d e s a u f d i e A n w e s e n h e i t e i n e s F r e m d k ö r p e r s anal y s i e r t . Z i e l des V o r h a b e n s i s t es: 1 . Die G e w e b s r e a k t i o n auf P o l y p r o p y l e n und Po lys ty ro l zu q u a n t i f i z i e r e n und zu verg l e i c h e n , d e n n d i e u n z u r e i c h e n d e B iove r t r ä g l i c h k e i t d e r b i s h e r v e r w e n d e t e n Polymere f ü h r t e z u e i n e r R e i h e v o n K o m p l i k a t i o n e n ; d a z u g e h ö r e n t o x i s c h e , e n t z ü n d l i c h e u n d a l l e r g i s c h e R e a k t i o n e n sowie g e l e g e n t l i c h sogar k a n z e r o g e n e A k t i v i t ä t e n d e s W e r k s t o f f e s . 2 . An B a s i s k r i t e r i e n de r G e w e b s v e r t r ä g l i c h k e i t f ü r K u n s t s t o f f I m p l a n t a t e m i t z u w i r k e n u n d z u h e l f e n S t a n d a r d s z u e n t w i c k e l n .

Bleomycin: effect on satellite DNA in mouse fibroblasts

The effect of Bleomycin on the semiconservative replication of mouse nuclear DNA has been studied. When asynchronously dividing mouse fibroblasts (L-cells) were grown in the presence of 5-bromodeoxyuridine (25mg/l medium) for 18h, three hybrid DNA bands with densities of 1.722, 1.752, and 1.761 kg/l appeared after caesium chloride density gradient centrifugation of nuclear DNA. In cells exposed to Bleomycin (100 mg/l) however, replication of satellite DNA is more strongly inhibited than is the replication of the main band DNA; preferentially the thymidine-rich hybrid duplex at 1.761 kg/l could no longer be detected. Der Einfluß von Bleomycin auf die semikonservative Reduplikation der Kern-DNS von Mäusefibroblasten wird untersucht. Nach 18 stündiger Inkubation asynchron sich teilender L-Zellen mit Bromdesoxyuridin (25 mg/l Nährmedium) trennt sich die Kern-DNS in der Cäsiumchlorid-Dichtegradientenanalyse in 3 hybride Banden mit den Dichten 1,722, 1,752 und 1,761 kg/l. Unter der Einwirkung von Bleomycin (100 mg/l) wird die Reduplikation der Satelliten-DNS, im besonderen die des thymidin-reichen Stranges, weit stärker gehemmt als die der Hauptbanden-DNS.