Die Stria terminalis als Einrichtung der Liquorresorption

Zusammenfassung Es wird die Auffassung unterbaut, daß die Stria terminalis eine Resorptions- bzw. Reinigungsfunktion des Liquors innehabe. Als Argumente hiefür werden angeführt: Das dort befindliche Furchenfeld, das embryonale Verhalten der Gegend, besondere Vaskularisationsverhältnisse, die Anordnung der Corpora amylacea, ferner gewisse pathologische Befunde.     

cDNA cloning of human inter-alpha-trypsin inhibitor discloses three different proteins

Inter-alpha-trypsin inhibitor (ITI) is a serum protein of unknown function. Part of the molecule (formerly called HI30) is closely related to a tumor-derived protein acting as a growth factor for endothelial cells. We screened a human liver cDNA expression library with antibodies raised against human ITI and isolated several clones which could be divided into three groups according to their DNA sequences. The cDNA of the first group codes for a protein composed of alpha 1-microglobulin (alpha 1M) and urinary trypsin inhibitor (UTI) and is identical to that encoded by a clone originally found by screening a human liver cDNA library with oligonucleotides derived from amino-acid sequences of the two Kunitz-type domains of UTI. The proteins derived from the cDNA of the second and the third group of clones are distantly related to each other, but unrelated to the protein derived from group 1 clones. Partial amino-acid sequencing of ITI isolated from serum allowed the verification of large parts of the cDNA-derived amino-acid sequences. The results favour the view that ITI is not a single chain protein, but rather a very tight complex of several components or a mixture of such complexes.     

Die Beeinflussung des Mutationseffektes bei Bacterium prodigiosum durch die Gasatmosphäre während oder nach der Bestrahlung mit kurzwelligem Ultraviolett

Ohne Zusammenfassung     

Impact of the long chain ω-acylceramides on the stratum corneum lipid nanostructure. Part 1: Thermotropic phase behaviour of CER[EOS] and CER[EOP] studied using X-ray powder diffraction and FT-Raman spectroscopy

The stratum corneum (SC), the outermost layer of the mammalian skin, is the main skin barrier. Ceramides (CERs) as the major constituent of the SC lipid matrix are of particular interest. At the moment, 11 classes of CERs are identified, but the effect of each single ceramide species is still not known.Therefore in this article, the thermotropic behaviour of the long chain ω-acylceramides CER[EOS] and CER[EOP] was studied using X-ray powder diffraction and FT-Raman spectroscopy.It was found that the ω-acylceramides CER[EOS] and CER[EOP] do not show a pronounced polymorphism which is observed for shorter chain ceramides as a significant feature. The phase behaviour of both ceramides is strongly influenced by the extremely long acyl-chain residue. The latter has a much stronger influence compared with the structure of the polar head group, which is discussed as extremely important for the appearance of a rich polymorphism. Despite the strong influence of the long chain, the additional OH-group of the phyto-sphingosine type CER[EOP] influences the lamellar repeat distance and the chain packing. The less polar sphingosine type CER[EOS] is stronger influenced by the long acyl-chain residue. Hydration is necessary for the formation of an extended hydrogen-bonding network between the polar head groups leading to the appearance of a long-periodicity phase (LPP). In contrast, the more polar CER[EOP] forms the LPP with densely packed alkyl chains already in the dry state.     

EVOLUTION AND EXTINCTION IN A CHANGING ENVIRONMENT: A QUANTITATIVE-GENETIC ANALYSIS

Because of the ubiquity of genetic variation for quantitative traits, virtually all populations have some capacity to respond evolutionarily to selective challenges. However, natural selection imposes demographic costs on a population, and if these costs are sufficiently large, the likelihood of extinction will be high. We consider how the mean time to extinction depends on selective pressures (rate and stochasticity of environmental change, and strength of selection), population parameters (carrying capacity, and reproductive capacity), and genetics (rate of polygenic mutation). We assume that in a randomly mating, finite population subject to density-dependent population growth, individual fitness is determined by a single quantitative-genetic character under Gaussian stabilizing selection with the optimum phenotype exhibiting directional change, or random fluctuations, or both. The quantitative trait is determined by a finite number of freely recombining, mutationally equivalent, additive loci. The dynamics of evolution and extinction are investigated, assuming that the population is initially under mutation-selection-drift balance. Under this model, in a directionally changing environment, the mean phenotype lags behind the optimum, but on the average evolves parallel to it. The magnitude of the lag determines the vulnerability to extinction. In finite populations, stochastic variation in the genetic variance can be quite pronounced, and bottlenecks in the genetic variance temporarily can impair the population's adaptive capacity enough to cause extinction when it would otherwise be unlikely in an effectively infinite population. We find that maximum sustainable rates of evolution or, equivalently, critical rates of environmental change, may be considerably less than 10% of a phenotypic standard deviation per generation.     

Regulation of thyroid hormone metabolism in rat liver fractions

The nature of the conversion of thyroxine (T₄) to triiodothyronine (T₃) and reverse triiodothyronine (rT₃) was investigated in rat liver homogenate and microsomes. A 6-fold rise of T₃ and 2.5-fold rise of rT₃ levels determined by specific radioimmunoassays was observed over 6 h after the addition of T₄. An enzymic process is suggested that converts T₄ to T₃ and rT₃. For T₃ the optimal pH is 6 and for rT₃, 9.5. The converting activity for both T₃ and rT₃ is temperature dependent and can be suppressed by heat, H₂O₂, merthiolate and by 5-propyl-2-thiouracil. rT₃ and to a lesser degree iodide, were able to inhibit the production of T₃ in a dose related fashion. Therefore the pH dependendy, rT₃ and iodide may regulate the availability of T₃ or rT₃ depending on the metabolic requirements of thyroid hormones.