Search results for "RATS"
showing 10 items of 3537 documents
A low repeat length in oligodendrocyte chromatin
1985
Abstract: The behavior of oligodendrocyte chromatin after micrococcal nuclease digestion of nuclei was assayed in brains of rats of four different ages. During oligodendrocyte differentiation, a decreasing sensitivity of the chromatin to enzymatic attack was observed. On the other hand, the nucleosomal repeat length showed a slight tendency to increase during development. It is worth noting that even the highest values reported here for “oligodendrocyte’ chromatin repeat lengths are significantly lower than 200 base pairs, the value previously reported by others for “non‐astrocytic glia.” Copyright © 1985, Wiley Blackwell. All rights reserved
Characterization of cells involved in the formation of granuloma. An ultrastructural study on macrophages, epitheloid cells, and giant cells in exper…
1981
In experimental tubulo-interstitial (anti-basement membrane) nephritis of the rat, granulomatous inflammation develops around immunologically altered tubular basement membranes. The present light- and electron microscopic studies indicate that in the course of the granulomatous reaction, tissue monocytes evolve from blood monocytes and pursue two independent pathways of differentation. On the one hand they may differentiate into macrophages ("distant from tubules") or, alternatively, into epitheloid cells ("adjacent to tubules"). The latter, through cell fusion, develop into multinucleated giant cells of the Langhans' type. The cytoplasmic components of the epitheloid cells and the multinuc…
Two-carbon bridge substituted cocaines: enantioselective synthesis, attribution of the absolute configuration and biological activity of novel 6- and…
1999
In an effort to learn more about the general structure-activity relationships of cocaine with the aim to elucidate those structural features that might confer antagonistic properties to such analogues, we describe herein our synthetic efforts to prepare two-carbon bridge functionalized (methoxylated and hydroxylated) analogues. Our approach makes use of a modification of the classical Willstatter synthesis of cocaine: Mannich type cyclization of acetonedicarboxylic acid monomethyl ester with methylamine hydrochloride and 2-methoxysuccindialdehyde in a citrate buffer solution afforded the 6- and 7-substituted 2-carbomethoxy-3-tropinones 3a,b and 4a,b in approximate yields of 64%. Reduction o…
Synthesis of new, UV-photoactive dansyl derivatives for flow cytometric studies on bile acid uptake.
2009
Four new fluorescent derivatives of cholic acid have been synthesized; they incorporate a dansyl moiety at 3 alpha-, 3 beta-, 7 alpha- or 7 beta- positions. These cholic acid analogs are UV photoactive and also exhibit green fluorescence. In addition, they have been demonstrated to be suitable for studying the kinetics of bile acid transport by flow cytometry.
Generation of chemotactic activity by immune complexes carrying clustered or nonclustered C&42horbar; sites
1973
Sensitized cells (EA) bearing different numbers of &42horbar; sites were tested for their ability to generate chemotactic activity from C-EDTA. From the results it can be shown that: 1 the amount of chemotactic activity generated parallels the number of &42horbar; sites bound to the cell surface, 2 all &42horbar; sites clustered around a single hemolytic site are enzymatically active as far as generation of chemotactic activity is concerned, and, 3 no difference can be demonstrated with IgG or IgM antibodies
Inhibition of liver trans-sulphuration pathway by propargylglycine mimics gene expression changes found in the mammary gland of weaned lactating rats…
2003
In the lactatingmammary gland, weaning produces mitochondrial cytochrome c release and nuclear DNA fragmentation, as determined by gel electrophoresis. This is followed by a significant decrease in lactation. Weaning for 2 h produces an early induction of the tumour suppressor/transcription factor p53, whereas the oncoprotein c-Jun and c-Jun N-terminal kinase are elevated after 24 h of weaning when compared with controls. The expression of p21cip1 and p27kip1, cyclin-dependent kinase inhibitors, was significantly higher in weaned rats when compared with control lactating rats. All the changes mentioned above also happen in the lactatingmammary gland when propargylglycine, an inhibitor of th…
Biocompatibility of alginates for grafting: impact of alginate molecular weight.
2003
Optimising microencapsulation technology towards the effective clinical transplantation has created the need for highly biocompatible alginates. Therefore, in this study the biocompatibility of different beads prepared from alginates with varying average molecular weight was examined. In some experiments the beads were covered with a multilayer membrane surrounded by an alginate layer. First of all, we found that beads made of a lower weight average alginate elicted a much stronger fibrotic response compared to beads made of a higher weight average alginate (LV-alginate > MV-alginate). The results were confirmed by the observation that the extent of tissue fibrosis was significantly increas…
Characterization and biodistribution of Au nanoparticles loaded in PLGA nanocarriers using an original encapsulation process
2021
Due to their imaging and radiosensitizing properties, ultrasmall gadolinium chelate-coated gold nanoparticles (AuNP) represent a promising approach in the diagnosis and the treatment of tumors. However, their poor pharmacokinetic profile, especially their rapid renal clearance prevents from an efficient exploitation of their potential for medical applications. The present study focuses on a strategy which resides in the encapsulation of AuNP in large polymeric NP to avoid the glomerular filtration and then to prolong the vascular residence time. An original encapsulation procedure using the polyethyleneimine (PEI) was set up to electrostatically entrap AuNP in biodegradable poly(lactic-co-g…
Magnetic resonance imaging of viral particle biodistribution in vivo
2006
We describe here a technique for the visualization of viral vector delivery by magnetic resonance imaging (MRI) in vivo. By conjugating avidin-coated baculoviral vectors (Baavi) with biotinylated ultra-small superparamagnetic iron oxide particles (USPIO), we are able to produce vector-related MRI contrast in the choroid plexus cells of rat brain in vivo over a period of 14 days. Ten microlitres of 2.5 x 10(10) PFU/ml nuclear-targeted LacZ-encoding Baavi with bUSPIO coating was injected into rat brain ventricles and visualized by MRI at 4.7 T. As baculoviruses exhibit restricted cell-type specificity in the rat brain, altered MRI contrast was detected in the choroid plexus of the injected ve…
Modifying the body distribution of HPMA-based copolymers by molecular weight and aggregate formation.
2011
There is a recognized need to create well-defined polymer probes for in vivo and clinical positron emission tomography (PET) imaging to guide the development of new generation polymer therapeutics. Using the RAFT polymerization technique in combination with the reactive ester approach, here we have synthesized well-defined and narrowly distributed N-(2-hydroxypropyl)methacrylamide homopolymers (pHPMA) (P1* and P2*) and random HPMA copolymers consisting of hydrophilic HPMA and hydrophobic lauryl methacrylate comonomers (P3* and P4*). The polymers had molecular weights below (P1* and P3*) and above the renal threshold (P2* and P4*). Whereas the homopolymers dissolve in isotonic solution as in…