Neue Gesichtspunkte zum 5. Buch Euklids

Summary The author's purpose is to read the main work of Euclid with modern eyes and to find out what knowledge a mathematician of today, familiar with the works of V. D. Waerden and Bourbaki, can gain by studying Euclid's theory of magnitudes, and what new insight into Greek mathematics occupation with this subject can provide.The task is to analyse and to axiomatize by modern means (i) in a narrower sense Book V. of the Elements, i.e. the theory of proportion of Eudoxus, (ii) in a wider sense the whole sphere of magnitudes which Euclid applies in his Elements. This procedure furnishes a clear picture of the inherent structure of his work, thereby making visible specific characteristics of Greek mathematics.After a clarification of the preconditions and a short survey of the historical development of the theory of proportions (Part I of this work), an exact analysis of the definitions and propositions of Book V. of the Elements is carried out in Part II. This is done word by word. The author applies his own system of axioms, set up in close accordance with Euclid, which permits one to deduce all definitions and propositions of Euclid's theory of magnitudes (especially those of Books V. and VI.).In this way gaps and tacit assumptions in the work become clearly visible; above all, the logical structure of the system of magnitudes given by Euclid becomes evident: not ratio — like something sui generis — is the governing concept of Book V., but magnitudes and their relation of having a ratio form the base of the theory of proportions. These magnitudes represent a well defined structure, a so-called Eudoxic Semigroup with the numbers as operators; it can easily be imbedded in a general theory of magnitudes equally applicable to geometry and physics.The transition to ratios — a step not executed by Euclid — is examined in Part III; it turns out to be particularly unwieldy. An elegant way opens up by interpreting proportion as a mapping of totally ordered semigroups. When closely examined, this mapping proves to be an isomorphism, thus suggesting the application of the modern theory of homomorphism. This theory permits a treatment of the theory of proportions as developed by Eudoxus and Euclid which is hardly surpassable in brevity and elegance in spite of its close affinity to Euclid. The generalization to a classically founded theory of magnitudes is now self-evident.

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Vorgelegt von J. E. Hofmann     

Determinant of efficiency of a monomeric enzyme: Acceleration by site-specific molecules for trypsin

Summary The interaction of a specific ligand at substrate binding site was shown to be responsible for the catalytic efficiency of trypsin. The reasoning of induced fit theory was refined by kinetic analysis of characteristic properties of inverse substrates.This work was supported by grants from the Ministry of Education, Science and Culture, Japan.     

Orally administered melatonin stimulates the 3α/β-hydroxysteroid oxidoreductase but not the 5α-reductase in the ventral prostate and seminal vesicles of pinealectomized rats

Summary Pinealectomized rats were treated orally with melatonin (MEL) for 14 days. Prostates and seminal vesicles were investigated for the activity of the 4-3-ketosteroid-5-oxidoreductase (5-R) and of the 3/-hydroxysteroid-oxidoreductase (3-HSO). The activity of the 3a-HSO was significantly stimulated (p<0.01, Friedman test) when compared to controls. The activity of the 5-R did not change significantly.This work was supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 34 (Endokrinologie).     

Glycoprotein biosynthesis in splenic cells. Purification of a microsomal galactosyl-transferase

Summary One part of the microsomal galactosyl-transferase activity of splenic cells of rats can by solubilized by the action of Triton X-100 and Tween 20. Its purification on a Sephadex G-200 column and by electrophoresis on a polyacrylamide gel leads to a solution of high specific enzymic activity.This work has benefited from the help of the Centre National de la Recherche Scientifique, the Direction des Recherches et Moyens d'Essais, the Institut National de la Santé et de la Recherche Médicale, the Fondation pour la Recherche Médicale Française the Délégation Générale à la Recherche Scientifique et Technique and the Université de Lyon (UER Lyon-Sud et Biologie Humaine).     

Amylase secretion from rat parotid glands as dependent on co-operation between sympathetic and parasympathetic nerves

Summary A slow, long-lasting degeneration secretion from the parotid gland was brought about in anaesthetized rats by section of the auriculo-temporal nerve 16–19 h in advance. This parasympathetic background activity greatly increased the secretion of amylase elicited by sympathetic nerve stimulation.Supported by grants from the Swedish Medical Research Council (project nr 00539) to N.E. and from the Medical Faculty, University of Lund, to P.G.     

The inability of nuclear dehydrogenating clostridia to oxidize bile salt hydroxyl groups

Summary In a survey of the intracellular bile salt oxidoreductase activity in fecal bacteria, 16 strains of nuclear dehydrogenating clostridia and 2 strains of non-nuclear dehydrogenatingC. paraputrificum were demonstrated unable to oxidize cholate at any of the 3 OH groups. Since nuclear dehydrogenation at the -1 and -4 position requires a 3-oxo precursor steroid, it appears that these organisms require the presence of a 3-hydroxysteroid dehydrogenating organism for nuclear dehydrogenation.This work is supported by the National Cancer Institute of Canada (IAM) and by the Cancer Research Campaign (MJH).     

β-alanine and α-L-alanine inhibit the exploratory activity of spontaneously hypertensive rats

Summary 1% -alanine and -L-alanine, when given for 7 days as the only drinking fluid, inhibited the exploratory activity of adult male spontaneously-hypertensive rats (SHR)_but not that of the normotensive Wistar-Kyoto rats (WKR). -Alanine decreased the taurine level in the liver of both strains and in the platelets of SHR. -Alanine decreased the taurine level in the liver of WKR and in the platelets of SHR.This study was supported by the Sigrid Jusélius Foundation.     

Differential sensitivity to ethidium bromide of replicative DNA synthesis and bleomycin-induced unscheduled DNA synthesis in permeable mouse sarcoma cells1

Summary Replicative DNA synthesis in permeable mouse sarcoma cells was more sensitive to ethidium bromide (EtBr) than bleomycin-induced unscheduled DNA synthesis (UDS). A similar difference in sensitivity to EtBr was observed between DNA polymerases and . The difference in sensitivity to EtBr of replicative DNA synthesis and UDS in the present system seems to reflect mainly the sensitivity difference between DNA polymerases and .Acknowledgments. The authors wish to thank Nippon Kayaku Co. (Tokyo, Japan) for providing copper-free bleomycin A₂. This research was supported in part by a grant from the Japan Ministry of Education, Science and Culture.     

ω10-Lipoxygenase products of α-linolenic acid are esterified to phospholipids inHydra vulgaris

We have recently reported the occurrence of 9(R)-hydroxy-, 9(R)-hydroperoxy- and 9-keto-octadeca-10E,12Z,15Z-trienoic acids (9-HOTrE, 9-HPOTrE and 9-KOTrE) inHydra vulgaris, and their biosynthesis from -linolenic acid (-LA) through the action of an enantioselective 10(R)-lipoxygenase (10-LO). Here we describe the finding of these -LA metabolites as esters to the 2-position of phosphatidylcholine, phosphatidylethanolamine and, in trace amounts, phosphatidylinositol. Small amounts of a compound co-eluting with an authentic standard of 9(R)-hydroxy-octadeca-10E,12Z-dienoic acid, a metabolite potentially derived from the action of 10-LO on linoleic acid, were also found esterified with phospholipids. Since direct peroxidation of membrane lipids has been described, experiments were aimed at establishing whether -LA metabolite-containing phospholipids could originate, inH. vulgaris, from either spontaneous or 10-LO-catalyzed oxidation of phospholipid-bound -LA. Incubation of either unlabelled or radiolabelled PUFA-containing phosphoglycerides withH. vulgaris 10-LO did not result in their peroxidation. This suggests that -LA and LA metabolites are incorporated into glycerophospholipids after their formation by 10-LO, and that, as in mamals, membrane phospholipids may serve as a reservoir for these bioactive compounds. This is the first example in an invertebrate species of lipoxygenase products esterified to phosphoglycerides.     

Relationship between A-type and C-type particles in Ehrlich ascites tumor cells

Summary Intracisternal and intracytoplasmic A-type particles were discovered in Ehrlich ascites tumor cells. In addition, mature and immature C-type particles were also seen in the intercellular space. It is believed that A particles may represent a precursor or a formative stage of the C particles.Acknowledgment. The author is grateful to Professor F. P. Lisowski for his advice and helpful criticisms and to Mr Y. S. Tong for his expert technical assistance. This project was supported by a grant from the Hong Kong University Research Grants Committee.     

Telomeres and chromosomal instability

Telomeres are distinctive structures, composed of a repetitive DNA sequence and associated proteins, which enable cells to distinguish chromosome ends from DNA double-strand breaks. Telomere alterations, caused by replication-mediated shortening, direct damage or defective telomere-associated proteins, usually generate chromosomal instability, which is observed in senescence and during the immortalization process. In cancer cells, this chromosome instability could be extended by their ability to repair chromosomes and terminate in break-fusion-bridge cycles. Dysfunctional telomeres can be healed by activation of telomerase or by the alternative mechanism of telomere lengthening. Activation of such telomere maintenance mechanisms may help to preserve the integrity of chromosomes even if they play a role in chromosomal instability. This review focuses on molecular processes involved in telomere maintenance and chromosomal instability associated with dysfunctional telomeres in mammalian cells.Received 24 July 2003; received after revision 5 September 2003; accepted 11 September 2003     

Rapid characterization and partial purification of various animal amine oxidases

Summary The use of chromatofocusing to obtain a rapid characterization of tissue amine oxidases from various mammals is proposed. This technique yields partially purified enzymes well suited for immunological studies. Chromatofocusing can be also used in a three-step purification of pig kidney diamine oxidase.Acknowledgments. This work has been in part supported by CNR, Special Project Chimica Fine Contract No. 80.02.107.95.     

Erythrocyte 2,3-diphosphoglycerate in anaemic sheep

Summary Experimental anaemia resulted in an increase of red cell 2,3-DPG from 0.11 M/gHb to 0.99 M in haemoglobin A sheep and from 0.21 M to 1.5 M in haemoglobin B sheep. Production of haemoglobin C as a result of anaemia was confined to haemoglobin A only. The results, therefore, appear to suggest that the rise in 2,3-DPG in the red blood cells of different haemoglobin types is independent of haemoglobin C.This work was supported by grants from the National Health and Medical Research Council, The Clive and Vera Ramaciotti New South Wales Foundations and Helena Rubinstein Foundation, Inc. We wish to thank Mr J. Sheedy for his expert technical assistance, and Professor G. J. Brewer for his constructive criticism.     

Prevention of estrogenic inhibition of adrenal 686-1686-1686-1686-2686-2686-2in rats

Summary The urinary protein _2u stimulates adrenal ⁵-3 dehydrogenase activity and prevents adrenal enlargement in estrogen-treated adult male rats.Acknowledgements. Dehydroepiandrosterone used in this study was donated by Organon(India) Ltd, Calcutta. This work received financial support from University Grants' Commission, New Delhi. The author's thanks are due to Prof. A. K. Maiti and Prof. C. Deb, Department of Physiology, Calcutta University, for their constant encouragement.     

The effect of chloramphenicol analogs on protein biosynthesis in a cell-freeEscherichia coli B system

a aaa a aa aa a a E. coli aa, a aa aa a , a a aa - a .

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Laboratory of Biological Investigations.

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Laboratory for Chemistry of Antibiotics.     

The molecular mechanisms of congenital hypofibrinogenaemia

Congenital hypofibrinogenaemia is characterized by abnormally low levels of fibrinogen and is usually caused by heterozygous mutations in the fibrinogen chain genes (, and ). However, it does not usually result in a clinically significant condition unless inherited in a homozygous or compound heterozygous state, where it results in a severe bleeding disorder, afibrinogenaemia. Various protein and expression studies have improved our understanding of how mutations causing hypo- and afibrinogenaemia affect secretion of the mature fibrinogen molecule from the hepatocyte. Some mutations can perturb chain assembly as in the 153 Cys Arg case, while others such as the B Leu Arg and the B414 Gly Ser mutations allow intracellular hexamer assembly but inhibit protein secretion. An interesting group of mutations, such as 284 Gly Arg and 375 Arg Trp, not only cause hypofibrinogenaemia but are also associated with liver disease. The nonexpression of these variant chains in plasma fibrinogen is due to retention in the endoplasmic reticulum, which in turn leads to hypofibrinogenaemia.Received 17 December 2003; received after revision 19 January 2004; accepted 21 January 2004     

Mass spectrometric determination of the amino acid sequence in arginine-containing peptides

aa, a-a a- a aa - aa a -a .     

Effects of DL-propranolol on the thermoregulatory responses of rats at different ambient temperatures

Summary Direct administration of propranolol (100–400 g) into the lateral cerebral ventricle of rats produced a dose-dependent hypothermia at ambient temperatures (T_a) of 8 and 22°C. The hypothermia was due to decreased metabolism and cutaneous vasodilation. The hypothermia induced by propranolol was antagonized by pretreatment with isoproterenol (50 g).This work was supported by the grants from the National Science Council (Republic of China) and the Pjing-Ling Neurological Foundation (Veterans General Hospital). The authors are grateful to Mr C.C. Wei for generous support.     

Isoforms of baker's yeast transketolase

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