Licht- und elektronenmikroskopische untersuchungen zur haftborstenentwicklung bei Tarentola m. mauritanica L. (Reptilia,Gekkonidae)

Zusammenfassung Kurz nach einer Hdutung wird bei Tarentola m. m. bereits die übemächste Epidermisgeneration — und somit auch die der Haftborsten —angelegt. Das geschieht vornehmlich in der Oz- (Oberhäutchenzellen-) und in der Hs-Schicht (clear layer). Zunächst entstehen die Aufspaltungen der Haftborstenenden, indem Keratinfilamentbündel nach einem bestimmten System von den Oz-Zellen aus in die Hs-Zellen einwachsen. Auf these Weise fungieren die Zellen der Hs-Schicht als Matrix der Haftborsten. Nach Abschluß dieses Prozesses werden die eigentlichen Haftborsten gebildet unter gleichzeitigem Auseinanderrücken der Hs- und Oz-Schichten. Die Hs-Schicht behdlt ihre Matrizen-Funktion bis zur anschließenden Häutung bei.

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Light and electron microscope studies of developing setae of Tarentola m. mauritanica (Rept., Gekkonidae)

Summary In Tarentola m. mauritanica the next epidermis generation but one and therefore the adhesive setae of the generation after this begin to develop shortly after a skin has been shed. This development takes place principally in the horny layer (Oz) and the clear layer. First bundles of keratin filaments radiate from the horny layer into the clear layer, thus giving rise to the split distal parts of the adhesive bristles. Thus the cells in the clear layer act as a matrix for the setae. When this stage is complete the formation of the setae proper begins, while the horny layer and the clear layer become separated from each other. The clear layer retains its function as matrix for the setae until the next time a skin is shed.

     

Cell retention-chemostat studies of hybridoma cells-analysis of hybridoma growth and metabolism in continuous suspension culture in serum-free medium

The steady-state metabolic parameters for a hybridoma cell line have been determined in continuous suspension-perfusion culture over a wide range of perfusion rates and cell bleed rates. Significant increases in viable cell concentrations and volumetric productivities were achieved at high perfusion rates and low cell bleed rates. At the low growth rates examined in this study, cellular metabolism shifted to become more oxidative, and as a result, the fraction of consumed substrate converted to inhibitory metabolic by-products was reduced. Specific antibody productivity was found to be non-growth associated. (c) 1993 John Wiley & Sons, Inc.     

A modified MOPP regimen in the treatment of Hodgkin's disease stage III B and IV (author's transl)

In a retrospective study 80 patients with Hodgkin's disease of stage III B (n = 32) and IV (n = 48) were investigated, who had been treated with a modified MOPP regimen. 28 patients (35%) were previously untreated. A completed remission was reached in 51 patients, a partial remission in 16, and 13 patients failed to respond. 16 patients had died in the observation period. Complete remissions were twice as frequent with 90% in stage III as compared with 45% in stage IV. The group of patients surviving 4 years was 92% in stage III and 62% in stage IV.     

Analysis of spacing in a periodic pattern

Colonies of hydroids exhibit periodic biological patterns. Polyps form on stolons at fixed distances, obeying distinct rules. The spacing mechanism is based on inhibition emanating from existing polyps, predominantly from the head of the polyp. Removal of polyps from young colonies reduces the distance between initiating polyps and newly formed polyps to 50% of the normal values. Head removal suffices to obtain an almost identical reduction. Polyp enlargement which increases the distance between the inhibition-emitting head and the stolon tissue reduces the intrastolonal range of inhibition. In the stolon tissue, decrease of inhibitory activity occurs. An increase in the stolon/polyp ratio of a colony reduces bud distances. The decay is, in part, due to loss of inhibitory activity into the external medium: if colonies are incubated in conditioned culture medium derived from crowded colonies having normally large interpolyp distances, bud distances increase in test colonies. The effectiveness of transfer of inhibitory activity from tissue into the medium depends on culture conditions. If convection is increased by agitation of the culture medium, the distances between polyp and bud decreases; viscosity enhancement of the culture medium reduces convection and bud distances become larger. This effect is compensated for by additional agitation of the viscosity enhanced culture medium. Our results support the idea that a lateral inhibition mechanism controls polyp spacing in the stolon and that inhibition is based on diffusible inhibitory compounds.     

Oxidation of methionine by X2.- in aqueous solution and characterization of some S therefore X three-electron bonded intermediates. A pulse radiolysis study

The primary steps of the oxidation of methionine, Met, by X2.- (X = Cl; Br, I, SCN) have been investigated using pulse radiolysis techniques. In principle, the mechanism follows the same pattern which has been established for the OH radical induced oxidation. It is characterized by a primary attack at the sulphur atom and the formation of sulphur-centred radical cations S+. and S therefore (+) S as key intermediates. At pH greater than pKa of the carboxyl group these can then oxidize the amino function intramolecularly, which subsequently leads to irreversible decarboxylation. An additional important intermediate is a S therefore X radical with a three-electron bond between sulphur and halide. This radical is linked to the OH . radical induced mechanism through the equilibrium S therefore X + Met in equilibrium with S therefore (+) S + X-, and in addition exists in the equilibria X2.- + Met in equilibrium with S therefore X + X-, S therefore X in equilibrium with S+. + X- and S therefore X in equilibrium with Met + X.. The S therefore X- species absorb at 410, 400, and 390 nm for X = I, Br, and Cl, respectively. Absolute rate constants have been measured for the reactions S therefore (+) S + I- (k = 1.0 x 10(10) mol-1 ls-1, pH 1.4), Br2.- + Met (k = 2.5 x 10(9), 1.7 x 10(9), and 2.0 x 10(9) mol-1 ls-1 at pH 1, 5, and 11, respectively) and Cl2.- + Met (k = 3.9 x 10(9) mol-1 ls-1, pH 1). Methionine is also oxidized by (SCN)2.- whereas any significant oxidation by I2.- is not indicated. N-acetylmethionine, a model compound for a sulphur-containing peptide, and some other methionine derivatives are oxidized by X2.- in the same way, that is, through electrophilic addition at the sulphur function. The results require reinterpretation of some data published in the literature and are discussed in view of a 'selective free radical attack'.     

Synthesis of spirocyclic σ1 receptor ligands as potential PET radiotracers,structure–affinity relationships and in vitro metabolic stability

Several 3H-spiro[[2]benzofuran-1,4′-piperidines] bearing a p-fluorobenzyl residue at the N-atom and various substituents in position 3 of the benzofuran system were synthesized. The crucial reaction steps are the addition of a lithiated benzaldehyde derivative to the p-fluorobenzylpiperidone 5 and the BF₃·OEt₂ catalyzed substitution of the methoxy group of 2a by various nucleophiles. Structure–affinity relationship studies revealed that compounds with two protons (2d), a methoxy group (2a), and a cyano group (2e) in position 3 possess subnanomolar σ₁ affinity (K_i = 0.18 nM, 0.79 nM, 0.86 nM) and high selectivity against the σ₂ subtype. The metabolites of 2a, 2d, and 2e, which were formed upon incubation with rat liver microsomes, were identified. Additionally, the rate of metabolic degradation of 2a, 2d, and 2e was determined and compared with the degradation rate of the non-fluorinated spirocyclic compound 1. For the synthesis of the potential PET tracers [¹⁸F]2a and [¹⁸F]2e two different radiosynthetic approaches were followed.     

Analysis of the HLA-ABC linkage disequilibrium: Decreasing strength of gametic association with increasing map distance

Summary 1242 HLA-ABC haplotypes of the North German population (Hamburg) as deduced by family analyses are described. They are in perfect agreement with recently published data by Mayr (1977) from Austria (Vienna) in all parameters tested: frequency of the single HLA-alleles, haplotype distribution and linkage disequilibrium values. Gametic association studies revealed that 69.4% of the B and C genes (map distance 0.2 cM) 36.9% of the A and C genes (0.6 cM), but only 23.2% of the A and B genes (0.8 cM) were significantly more often combined than expected due to their frequencies. From these findings it seems likely that the linkage disequilibrium within the MHC is rather due to a short evolutionary period than to selective forces. Some observations as to the most common European haplotype A1,B8 are discussed.     

An erythrocyte vesicle protein exported by the malaria parasite promotes tubovesicular lipid import from the host cell surface

Plasmodium falciparum is the protozoan parasite that causes the most virulent of human malarias. The blood stage parasites export several hundred proteins into their host erythrocyte that underlie modifications linked to major pathologies of the disease and parasite survival in the blood. Unfortunately, most are 'hypothetical' proteins of unknown function, and those that are essential for parasitization of the erythrocyte cannot be 'knocked out'. Here, we combined bioinformatics and genome-wide expression analyses with a new series of transgenic and cellular assays to show for the first time in malaria parasites that microarray read out from a chemical perturbation can have predictive value. We thereby identified and characterized an exported P. falciparum protein resident in a new vesicular compartment induced by the parasite in the erythrocyte. This protein, named Erythrocyte Vesicle Protein 1 (EVP1), shows novel dynamics of distribution in the parasite and intraerythrocytic membranes. Evidence is presented that its expression results in a change in TVN-mediated lipid import at the host membrane and that it is required for intracellular parasite growth, but not invasion. This exported protein appears to be needed for the maintenance of an essential tubovesicular nutrient import pathway induced by the pathogen in the host cell. Our approach may be generalized to the analysis of hundreds of 'hypothetical' P. falciparum proteins to understand their role in parasite entry and/or growth in erythrocytes as well as phenotypic contributions to either antigen export or tubovesicular import. By functionally validating these unknowns, one may identify new targets in host-microbial interactions for prophylaxis against this major human pathogen.     

Systematic Phenotyping of a Large-Scale Candida glabrata Deletion Collection Reveals Novel Antifungal Tolerance Genes

The opportunistic fungal pathogen Candida glabrata is a frequent cause of candidiasis, causing infections ranging from superficial to life-threatening disseminated disease. The inherent tolerance of C. glabrata to azole drugs makes this pathogen a serious clinical threat. To identify novel genes implicated in antifungal drug tolerance, we have constructed a large-scale C. glabrata deletion library consisting of 619 unique, individually bar-coded mutant strains, each lacking one specific gene, all together representing almost 12% of the genome. Functional analysis of this library in a series of phenotypic and fitness assays identified numerous genes required for growth of C. glabrata under normal or specific stress conditions, as well as a number of novel genes involved in tolerance to clinically important antifungal drugs such as azoles and echinocandins. We identified 38 deletion strains displaying strongly increased susceptibility to caspofungin, 28 of which encoding proteins that have not previously been linked to echinocandin tolerance. Our results demonstrate the potential of the C. glabrata mutant collection as a valuable resource in functional genomics studies of this important fungal pathogen of humans, and to facilitate the identification of putative novel antifungal drug target and virulence genes.     

Isocitrate dehydrogenase 1 R132C mutation occurs exclusively in microsatellite stable colorectal cancers with the CpG island methylator phenotype

The CpG Island Methylator Phenotype (CIMP) is fundamental to an important subset of colorectal cancer; however, its cause is unknown. CIMP is associated with microsatellite instability but is also found in BRAF mutant microsatellite stable cancers that are associated with poor prognosis. The isocitrate dehydrogenase 1 (IDH1) gene causes CIMP in glioma due to an activating mutation that produces the 2-hydroxyglutarate oncometabolite. We therefore examined IDH1 alteration as a potential cause of CIMP in colorectal cancer. The IDH1 mutational hotspot was screened in 86 CIMP-positive and 80 CIMP-negative cancers. The entire coding sequence was examined in 81 CIMP-positive colorectal cancers. Forty-seven cancers varying by CIMP-status and IDH1 mutation status were examined using Illumina 450K DNA methylation microarrays. The R132C IDH1 mutation was detected in 4/166 cancers. All IDH1 mutations were in CIMP cancers that were BRAF mutant and microsatellite stable (4/45, 8.9%). Unsupervised hierarchical cluster analysis identified an IDH1 mutation-like methylation signature in approximately half of the CIMP-positive cancers. IDH1 mutation appears to cause CIMP in a small proportion of BRAF mutant, microsatellite stable colorectal cancers. This study provides a precedent that a single gene mutation may cause CIMP in colorectal cancer, and that this will be associated with a specific epigenetic signature and clinicopathological features.