ZIB

1

Digitale Medien

APP is required during an early phase of memory formation (2000)

Mileusnic, R. ; Lancashire, C. L. ; Johnston, A. N. B. ; [weitere]

Oxford, UK : Blackwell Science Ltd

European journal of neuroscience 12 (2000), S. 0

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ISSN: 1460-9568

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Medizin

Notizen: The amyloid β/A4 protein precursor (APP) has been shown to be implicated in age-associated plastic changes at synapses that might contribute to memory loss in Alzheimer's disease. As APP has previously been reported to have multiple functions during normal development, we have employed a one-trial passive avoidance task in day-old chicks to study its role in the process of memory formation. Administration of anti-APP antibodies, injected 30 min pretraining, prevented memory for a one-trial passive avoidance task in day-old chicks without effects on general behaviour or initial acquisition. Amnesia was apparent by 30 min post-training and lasted for at least 24 h. The same result was obtained by down-regulation of APP expression by APP-antisense, injected 8–12 h pretraining. However, injections of anti-APP antibodies or APP antisense at later post-training time did not cause amnesia for the task. Unlike antibodies and antisense, injection of the APP328–332 pentapeptide, in either orientation, 30 min pretraining, rescued the memory and prevented antisense-induced amnesia. The post-training time within which the antibody- and antisense-induced amnesia, and within which the APP peptides prevent amnesia, correspond to that during which memory formation is vulnerable to disruption of the putative signal transduction functions of APP. These results suggest that: (i) APP is required during an early phase of memory formation, and (ii) the memory enhancing effect of secretory APP is localized within a 5-mer sequence of growth-promoting domain.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1460-9568.2000.01344.x

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2

Digitale Medien

The effects of variable bulk composition on the melting systematics of fertile peridotitic assemblages (2000)

Pickering-Witter, J. ; Johnston, A. D.

Springer

Contributions to mineralogy and petrology 140 (2000), S. 190-211

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ISSN: 1432-0967

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie

Notizen: Abstract Experiments were conducted at 1 GPa on four starting materials to investigate the effects of variable mineral proportions on the melting systematics of compositionally fertile peridotitic assemblages. Starting materials were constructed by recombining Kilbourne Hole xenolith mineral separates by weight into four mixtures with mineral proportions olivine (Ol): orthopyroxene (Opx): clinopyroxene (Cpx): spinel (Sp) of 0.50:0.07:0.40:0.03 (FER-B), 0.50:0.46:0.01:0.03 (FER-C), 0.50:0.30:0.10:0.10 (FER-D), and 0.50:0.235:0.235: 0.03 (FER-E). Experiments were performed on a 1.27-cm (0.5 in.) piston-cylinder apparatus over the temperature interval 1270–1390 °C, using a variation of the diamond aggregate melt extraction technique employing vitreous carbon spheres in place of diamonds as the melt extraction layer. The solidus temperatures are similar for all the starting materials, with an average value of 1250 °C. In FER-D and -E, the near-solidus melting reaction for a lherzolite assemblage was determined to be of the form Cpx + Opx + Sp → melt + Ol. A subsequent reaction of the form Opx + Sp → melt + Ol was determined for FER-D after the exhaustion of Cpx. Over the entire temperature interval investigated for FER-B and -C, reactions were determined to be of the form Cpx + Sp → melt + Ol and Opx + Sp → melt + Ol, respectively. Melt percent (F) vs temperature (T) curves are concave up for all starting materials, demonstrating that isobaric melt productivity increases with progressive batch melting. At any given melt fraction, (dF/dT)P increases with increasing amount of Cpx in the starting material, indicating that the modal proportion of Cpx is one of the primary controls on isobaric melt productivity of upwelling peridotite. The concave up melt productivity functions for peridotitic assemblages determined in this study suggest that assuming linear or concave down melt productivity functions for modeling mantle melting may not be appropriate.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004100000183

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3

Digitale Medien

Thermal effects of polymerization of methyl-methacrylate on small tubular bones (1987)

Schultz, R. J. ; Johnston, A. D. ; Krishnamurthy, S.

Springer

International orthopaedics 11 (1987), S. 277-282

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ISSN: 1432-5195

Schlagwort(e): Methyl methocrylate Heat of polymerisation ; Small bones

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: Résumé Le but de ce travail est d'étudier les effets thermiques de la polymérisation sur les petits os longs. Les résultats montrent seulement, durant la prise du ciment, une élevation modérée de la température dans la cavité médullaire de ces os. L'élévation maximale (11° 7) est dans les limites de tolérance des cellules osseuses vivantes. Il a été démontré que les petites quantités de méthyl-métacrylate refroidissent plus rapidement, donc que diminuent davantage les effets nuisibles de la chaleur. Les examens histologiques ne montrent aucune altération due aux effets thermiques de la polymérisation du méthyl-métacrylate sur les petits os longs ni sur les tissus de recouvrement.

Notizen: Summary This study was designed to investigate the thermal effects of polymerization on small tubular bones. The results demonstrated only a slight increase in temperature during cement-curing in the medullary canals of these bones. The maximum rise (11.7° C) was within the levels of tolerance for living bone cells. It was demonstrated that the small volumes of methyl-methacrylate cool more rapidly, hence further decreasing the deleterious effects of heat. The histological studies showed no recognisable adverse reaction to the thermal effects of methyl-methacrylate polymerization on small tubular bones or on the overlying tissue.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00271461

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4

Digitale Medien

Identification of two classes of Rhizobium phaseoli genes required for melanin synthesis, one of which is required for nitrogen fixation and activates the transcription of the other (1987)

Borthakur, D. ; Lamb, J. W. ; Johnston, A. W. B.

Springer

Molecular genetics and genomics 207 (1987), S. 155-160

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ISSN: 1617-4623

Schlagwort(e): Gene regulation ; Melanin synthesis ; Nitrogen fixation ; Phaseolus beans ; Rhizobium phaseoli

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary The symbiotic plasmid pRP2JI of Rhizobium phaseoli strain 8002 was shown to contain two separate regions of DNA which are required and sufficient for the synthesis of the pigment melanin. One of these regions containing the class II mel gene(s) was located to other genes involved in nodulation and in nitrogen fixation. Mutations in this region abolished both the ability to synthesize melanin and to fix nitrogen in Phaseolus bean root nodules. Mutations in the other, unlinked region, containing class I mel gene(s), also abolished melanin synthesis but did not affect symbiotic nitrogen fixation. Transcriptional fusions between the class I mel gene and the Escherichia coli lacZ gene were constructed and it was demonstrated that the class II mel gene(s) activated their transcription in free-living culture. Further, strains containing the cloned regulatory class II gene(s) synthesized melanin when growing in minimal medium, in contrast to wild-type strains which became pigmented only in complete medium containing yeast extract and tryptone. It was shown by hybridization experiments that the regulatory mel gene was closely linked to or may correspond to the regulatory nifA gene; a fragment of R. phaseoli DNA which included the class II gene(s) of R. phaseoli hybridized to a previously identified nifA-like gene of R. leguminosarum, the species that nodulates peas.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00331503

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5

Digitale Medien

Sequence of psi, a gene on the symbiotic plasmid of Rhizobium phaseoli which inhibits exopolysaccharide synthesis and nodulation and demonstration that its transcription is inhibited by psr, another gene on the symbiotic plasmid (1987)

Borthakur, D. ; Johnston, A. W. B.

Springer

Molecular genetics and genomics 207 (1987), S. 149-154

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ISSN: 1617-4623

Schlagwort(e): Beans ; DNA Sequence ; Gene regulation ; Nitrogen fixation ; Nodulation ; Rhizobium

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary A gene termed psi (polysaccharide inhibition), located close to the nodulation genes of the Rhizobium phaseoli symbiotic plasmid pRP2JI inhibited exopolysaccharide synthesis (EPS) and nodulation ability (Nod) in Rhizobium when it was cloned in a multicopy plasmid. The sequence of psi showed that it specified a polypeptide of mol. wt. 10000 that may be associated with the membrane of Rhizobium. A second gene, psr (polysaccharide restoration), was located on pRP2JI. When cloned in multicopy plasmids, psr overcame the EPS and Nod defects in strains carrying multicopy psi. Strains with multicopy psr induced non-fixing nodules on Phaseolus beans. Using gene fusions between psi and lacZ, it was shown that psi inhibited transcription of psr.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00331502

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6

Digitale Medien

Analysis for naturally occuring radionuclides at environmental concentrations by gamma spectrometry (1987)

Murray, A. S. ; Marten, R. ; Johnston, A. ; [weitere]

Springer

Journal of radioanalytical and nuclear chemistry 115 (1987), S. 263-288

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ISSN: 1588-2780

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Energietechnik

Notizen: Abstract The analytical potential of low level, high resolution gamma-ray spectrometry for naturally occurring radionuclides at environmental levels is described, with particular emphasis on detector background levels and sensitivity. Comparisons are drawn between the performance of a specially designed low background detector system, and that of standard “off the shelf” devices. Sample characteristics, calibration procedures and checks, are described, and empirical minimum detection limits of between 0.4 Bq·kg−1 (226Ra,228Th) and 10 Bq·kg−1 (210Pb) are derived for soil or sediment samples of about 250 g. Representative analyses of a variety of environmental samples, including water, plant material, animal tissue and sediment, are given to illustrate the routine use of the spectrometer.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02037443

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7

Digitale Medien

Adsorption of N-phenylglycine on hydroxyapatite: Role in the bonding procedure of a restorative resin to dentin (1987)

Misra, D. N. ; Johnston, A. D.

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 21 (1987), S. 1329-1339

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ISSN: 0021-9304

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Medizin , Technik allgemein

Notizen: The adsorption of N-phenylglycine (NPG) onto synthetic hydroxyapatite from ethanol solutions was studied to elucidate the role of surface-active moieties in determining the character of adsorption, and to explore the role of NPG in a bonding procedure of restorative resin to dentin. The adsorption isotherm of N-phenylglycine is reversible (and Langmuirian) from ethanol (99.8%). At maximum adsorption the phenyl rings of the adsorbed molecules lie flat on the surface and the carboxylate oxygens and amino nitrogens are anchored to the surface. The N-phenylglycine serves as an amine accelerator since the peroxide containing monomer polymerizes with the adsorbate-covered apatite. The diametral tensile strength of this composite is approximately equal to the composite filled with untreated apatite. The role of various factors contributing to adhesive strength in the bonding procedure is also discussed.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/jbm.820211105

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