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  • 11
    Electronic Resource
    Electronic Resource
    Experiments on antigenicity and osteogenicity in allotransplanted cancellous bone (1990)
    Springer
    International orthopaedics 14 (1990), S. 243-248 
    Details
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Cette étude expérimentale a été entreprise chez la souris pour apprécier les procédés de stockage de l'os spongieux allogène. Les greffes spongieuses ont été conservées à −80° C, à −196° C ou lyophilisées. Elles ont été implantées dans une cavité du fémur receveur et, au bout d'une semaine, l'activité cellulaire cinétique a été analysée par autoradiographie. Pour l'étude immunologique les greffes ont été implantées dans le muscle du receveur et sept semaines plus tard leurs propriétés sensibilisatrices ont été évaluées par la toxicité sur les lymphocytes T-killer et le test de cytotoxicité dépendant du complément. La capacité ostéogénique des greffes réfrigérées à −196° C était égale ou supérieure à celle des greffes lyophilisées, mais elle était faible quand elles étaient conservées à −80° C. L'immunogénicité n'était pas affectée par ces trois méthodes de conservation et était très analogue à celle des autogreffes fraîches. L'antigénicité des allogreffes peut être réduite par la lyophilisation. Nous pensons que le potentiel ostéogénique, supérieur après refroidissement à −196° C est lié au moindre degré de dégénérescence de la matrice osseuse.
    Notes: Summary This experimental study was undertaken in mice to investigate the procedures for storage of allogenic cancellous bone. Cancellous grafts were were stored at −80° C, −196° C or freeze dried. Grafts were implanted into a defect in the recipient's femur and after one week the cellular kinetic activity was analysed by autoradiography. For immunological study, the grafts were implanted into the recipient's muscle, and 2 weeks later the sensitising properties were examined by killer T-cell toxicity and the complement dependent cytotoxicity test. The capacity for osteogenesis of grafts frozen at −196° C was similar to or higher than those freeze dried, but it was low when storage was at −80° C. Immunogenicity was not affected by these three methods of storage and was very similar to that of fresh autografts. Antigenicity of allografts can be decreased by the freezing procedure. We suggest that the greater osteogenic potency after freezing at 196° C is related to the lesser degree of degeneration of the bone matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178753
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  • 12
    Electronic Resource
    Electronic Resource
    Phase advances of circadian rhythms in somatostatin depleted rats: effects of cysteamine on rhythms of locomotor activity and electrical discharge of the suprachiasmatic nucleus (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 677-685 
    Details
    ISSN: 1432-1351
    Keywords: Circadian rhythm ; Suprachiasmatic nucleus ; Cysteamine ; Somatostatin ; Brain slice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Somatostatin is synthesized in the suprachiasmatic nucleus (SCN), a circadian pacemaker in mammals. To explore the functional significance of somatostatin in the circadian system, we examined rhythms of rat locomotor activity and electrical firing rate of SCN neurons in the brain slice after temporal depletion of somatostatin levels in the SCN. Intraperitoneal administration of cysteamine (200 mg/kg), a somatostatin depletor, significantly reduced somatostatin level in the in vivo SCN 5 min after injection and kept low level as long as 3 to 4 days. This administration, on the other hand, induced significant phase advances of about 51 min in the subsequent free-running rhythm of locomotor activity of the rat. A marked phase advance in the circadian rhythm of firing rate in the SCN was also observed after administration of cysteamine in coronal hypothalamic slices. These persistent phase shifts after administration of a somatostatin depletor may suggest that the change of somatostatin level in the SCN have a feedback influence on the circadian pacemaker.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191840
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  • 13
    Electronic Resource
    Electronic Resource
    A polymorphic region of the human cytomegalovirus genome encoding putative glycoproteins (1994)
    Springer
    Archives of virology 137 (1994), S. 117-121 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A region of the human cytomegalovirus genome (corresponding to nt 17973-19945 of strain AD169) was analyzed by restriction fragment length polymorphism. Rsa I digestion of the region showed 20 distinct patterns in agarose gel electrophoresis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01311177
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  • 14
    Electronic Resource
    Electronic Resource
    Enhancement of protein secretion by optimizing protein synthesis: isolation and characterization of Escherichia coli mutants with increased secretion ability of alkaline phosphatase (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 163-169 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Overexpression of the Escherichia coli phoA gene, coding for alkaline phosphatase, on multicopy plasmids caused the accumulation of the precursor form of alkaline phosphatase. The cells lost their viability by a half-life of 60 min and exhibited high sensitivity to 1% sodium dodecyl sulfate (SDS), suggesting that the assembly of the surface proteins were affected by overexpression of the phoA gene. From the cells exhibiting resistance to 1% SDS, we obtained 20 mutants that secrete more alkaline phosphatase into the periplasmic space. Three representatives of the mutants accumulated no precursor molecules and secreted alkaline phosphatase by five- to six-fold that of the wild-type cells carrying multicopy phoA. In all of the three mutants, the amount of phoA transcripts were two to four times less than those in the wild-type cells, indicating that the ability to secrete a large amount of alkaline phosphatase was conferred by decreasing the synthetic rates of the phoA gene product. When the promoter of phoA was replaced with the tacI promoter and the expression level of the phoA gene was regulated with isopropyl-1-thio-β-d-galactoside, the secretion of alkaline phosphatase into the periplasm decreased as the synthetic rate of the phoA gene product increased over a threshold. All these results indicate that overproduction of the phoA gene product causes defects in the secretion of alkaline phosphatase and that the regulation of the expression level is essential for efficient translocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186954
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  • 15
    Electronic Resource
    Electronic Resource
    Enhancement of protein secretion by optimizing protein synthesis: isolation and characterization of Escherichia coli mutants with increased secretion ability of alkaline phosphatase (1994)
    Springer
    Applied microbiology and biotechnology 41 (1994), S. 163-169 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Overexpression of the Escherichia coli phoA gene, coding for alkaline phosphatase, on multicopy plasmids caused the accumulation of the precursor form of alkaline phosphatase. The cells lost their viability by a half-life of 60 min and exhibited high sensitivity to 1% sodium dodecyl sulfate (SDS), suggesting that the assembly of the surface proteins were affected by overexpression of the phoA gene. From the cells exhibiting resistance to 1% SDS, we obtained 20 mutants that secrete more alkaline phosphatase into the periplasmic space. Three representatives of the mutants accumulated no precursor molecules and secreted alkaline phosphatase by five- to six-fold that of the wild-type cells carrying multicopy phoA. In all of the three mutants, the amount of phoA transcripts were two to four times less than those in the wild-type cells, indicating that the ability to secrete a large amount of alkaline phosphatase was conferred by decreasing the synthetic rates of the phoA gene product. When the promoter of phoA was replaced with the tacI promoter and the expression level of the phoA gene was regulated with isopropyl-1-thio-β-D-galactoside, the secretion of alkaline phosphatase into the periplasm decreased as the synthetic rate of the phoA gene product increased over a threshold. All these results indicate that overproduction of the phoA gene product causes defects in the secretion of alkaline phosphatase and that the regulation of the expression level is essential for efficient translocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050125
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  • 16
    Electronic Resource
    Electronic Resource
    Detection of manganese superoxide dismutase mRNA in the theca interna cells of rat ovary during the ovulatory process by in situ hybridization (1994)
    Springer
    Histochemistry and cell biology 102 (1994), S. 173-176 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract To determine the possible involvement of reactive oxygen species in ovulation, dynamic aspects of superoxide dismutase (SOD) isozyme were studied in the ovaries of rats by in situ hybridization histochemistry. Previously, mRNA levels of ovarian manganese superoxide dismutase (Mn-SOD) were reported markedly to increase whilst enzymic activity of Mn-SOD decreased during the ovulatory process after treating immature rats with 10 and 5 Units, respectively, of pregnant mare serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG). Levels of Cu/Zn-SOD activity and Cu/Zn-SOD mRNA were reported to remain unchanged throughout ovulation. This increase in the Mn-SOD mRNA level was shown in the present study by in situ hybridization to be localized to the theca interna cells throughout the PMSG/HCG-induced ovulatory process. The observations suggest that the turnover rate of Mn-SOD but not Cu/Zn-SOD increases specifically in the mitochondria of these cells. SOD has been postulated to play important roles in steroidogenesis. The relationship is discussed between mitochondrial functions in steroid-secreting cells and superoxide radicals and related metabolite(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00268893
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  • 17
    Electronic Resource
    Electronic Resource
    Reductions in recruitment force thresholds in human single motor units by successive voluntary contractions (1990)
    Springer
    Experimental brain research 82 (1990), S. 227-230 
    Details
    ISSN: 1432-1106
    Keywords: Motor units ; Voluntary contraction ; Muscle force ; Potentiation ; Stretch reflex ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recruitment force thresholds of biceps brachii single motor units were studied in 4 male subjects before and after an isometric muscle contraction, passive muscle stretch, or following successive muscle contractions, muscle stretches or during alternations between muscle stretches and muscle contractions. Isometric muscle contractions of 5 s duration decreased subsequent single motor unit force thresholds. These force thresholds could usually be reset at or near precontraction force threshold values by passive muscle stretch induced by elbow extension. Single motor units showing reduced force thresholds following contraction were momentarily derecruited during and/or after muscle stretch. Successive muscle stretches alone did not significantly alter single motor unit force thresholds. In contrast, single motor unit recruitment force thresholds during successive weaker contractions were progressively lowered. Intercontraction muscle stretches maintained the single motor unit force thresholds at or near the initial force threshold level. The mechanism(s) underlying a muscle contraction-induced lowering of single motor unit force thresholds may reside in stretch reflex pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230858
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  • 18
    Electronic Resource
    Electronic Resource
    Application of a new, self-recording, vibratory sensation meter to measure temporary threshold shift of vibratory sensation caused by local vibration exposure (1994)
    Springer
    International archives of occupational and environmental health 66 (1994), S. 97-102 
    Details
    ISSN: 1432-1246
    Keywords: Human skin ; Vibratory sensation Vibration exposure ; Threshold shift ; Acute effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A new, self-recording, vibratory sensation meter measures temporary threshold shifts of vibratory sensation (TTSv) on a finger tip. After exposure to hand-transmitted vibration with exposure frequencies 63 Hz, 200 Hz and 500 Hz, and levels of acceleration 1 g, 2 g, 4 g and 8 g, fingertip measurements were obtained. Temporary threshold shift immediately after the vibratory exposure (TTSVv,0) was estimated for each exposure from the regression analysis by approximation of an exponential function. Time constant (tc) was also estimated at the same time by the analysis. The coefficients of determination were large. Thus, the fit of the exponential function is very good for each exposure. The tc corresponds to the recovering velocity of the temporary shift and implies the half-life period of TTSv. These parameters enable us to examine more generally the relationships of TTSv to the characteristics of exposure vibration, subject and other conditions. On this basis, the estimated TTSv,0 and tc were used to examine the dependency of TTSv on the characteristics of the exposure vibration and the subject. The most effective frequency under the level of 4 g is thought to be between 200 Hz and 500 Hz. TTSv,0 of each subject proportionally increased with power of acceleration. The coefficient of determination on regression analysis was large. This result enables us to estimate TTSv,0 at an arbitrary level of acceleration by use of a regression equation derived from experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00383364
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  • 19
    Electronic Resource
    Electronic Resource
    Salivary cortisol for monitoring circadian rhythm variation in adrenal activity during shiftwork (1993)
    Springer
    International archives of occupational and environmental health 64 (1993), S. 499-502 
    Details
    ISSN: 1432-1246
    Keywords: Salivary cortisol ; Circadian rhythm ; Shiftwork
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To examine the validity of salivary cortisol for monitoring circadian rhythm variation in adrenal activity during shiftwork, saliva and blood samples were collected at 4-h intervals in experimental short-term shifts, i.e., day (work 0830–1600 h; sleep 0030–0800 h), evening (work 1630–2400 h; sleep 0430–1200 h), and night (work 0030–0800 h; sleep 1230–2000 h) shifts over 2 days. Cortisol levels, determined by radioimmunoassay, and the circadian profiles of saliva and sera were compared. The salivary cortisol showed relatively low levels, the 2-day mean value being 3.1%–3.3% that of serum total cortisol through all shifts. Significant differences in the serum to saliva cortisol ratios were noted among shifts and subjects. When expressed as a relative percentage of a 2-day mean value, however, salivary cortisol paralleled the modified circadian profiles of serum total cortisol of the evening and night shifts, with no significant time lag and no difference in magnitude. The cosinor analysis supported this finding. Thus, salivary cortisol appears to be an excellent measure for monitoring circadian rhythm variation in adrenal activity in healthy individuals during shiftwork.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381098
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  • 20
    Electronic Resource
    Electronic Resource
    Theory of superconductivity. 3. 2D conduction bands for high Tc. Bose-Einstein condensation transition of the third order (1992)
    Springer
    Journal of superconductivity 5 (1992), S. 219-237 
    Details
    ISSN: 1572-9605
    Keywords: Theory of superconductivity ; new formula forT c ; high-T c superconductor ; Bose-Einstein condensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A general theory of superconductivity is developed, starting with a BCS Hamiltonian in which the interaction strengths (V 11,V 22,V 12) among and between “electron” (1) and “hole” (2) Cooper pairs are differentiated, and identifying “electrons” (“holes”) with positive (negative) masses as those Bloch electrons moving on the empty (filled) side of the Fermi surface. The supercondensate is shown to be composed of equal numbers of “electron” and “hole” ground (zero-momentum) Cooper pairs with charges ±2e and different masses. This picture of a neutral supercondensate naturally explains the London rigidity and the meta-stability of the supercurrent ring. It is proposed that for a compound conductor the supercondensate is formed between “electron” and “hole” Fermi energy sheets with the aid of optical phonons having momenta greater than the minimum distance (momentum) between the two sheets. The proposed model can account for the relatively short coherence lengthsξ observed for the compound superconductors including intermetallic compound, organic, and cuprous superconductors. In particular, the model can explain why these compounds are type II superconductors in contrast with type I elemental superconductors whose condensate is mediated by acoustic phonons. A cuprous superconductor has 2D conduction bands due to its layered perovskite lattice structure. Excited (nonzero momentum) Cooper pairs (bound by the exchange of optical phonons) aboveT c are shown to move like free bosons with the energy-momentum relationɛ=1/2vFq. They undergo a Bose-Einstein condensation atT c = 0.977ħv F k b −1 n 1/2, wheren is the number density of the Cooper pairs. The relatively high value ofT c (∼100 K) arises from the fact that the densityn is high:n 1/2∼ξ−1 ∼107 cm−1. The phase transition is of the third order, and the heat capacity has a reversed lambda (λ)-like peak atT c .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617622
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