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41.
The neuronal cytoskeleton is one of the most profoundly altered organelles in late life neuro-degenerative disorders that are characterized by progressive impairments in cognitive abilities. The elucidation of the protein building blocks of these organelles as well as advances in understanding how these proteins become altered in Alzheimer's disease (AD) and other less common dementing illnesses, i.e., diffuse Lewy body disease (DLBD) or the Lewy body variant of AD (LBVAD), will provide insights into the molecular basis of these disorders. Within, we review evidence that normal adult human tau is abnormally phosphorylated and converted into the subunits of AD paired helical filaments (PHFs), and that Lewy bodies (LBs) represent accumulation of altered neurofilament (NF) triplet subunits. Although the precise biological consequences of PHF and LB formation in neurons is unknown, growing evidence suggests that the formation of PHFs and LBs from normal neuronal cytoskeletal proteins could have deleterious effects on neuronal function and survival. Finally, insights into the composition of PHFs and LBs could lead to the development of novel strategies for the timely and accurate diagnosis of AD, DLBD and the LBVAD. 相似文献
42.
S Dittrich A Schuth H von Baeyer C Grosse-Siestrup PE Lange G Kaczmarczyk 《Canadian Metallurgical Quarterly》1998,123(7):809-813
STUDY DESIGN: Cross-sectional study with two age cohorts. OBJECTIVE: To assess whether women receiving hormone replacement therapy after menopause have a higher prevalence of back problems than women who do not receive such treatment. BACKGROUND: Back pain is a common medical problem throughout life and especially during pregnancy. Hormonal factors have been proposed as a possible contributor. PATIENTS AND METHODS: A validated postal questionnaire was sent in early 1995 to all 1324 women of 55 years and 56 years of age residing in Link?ping, Sweden. This questionnaire included questions about current hormone replacement treatment, previous and current back problems, medical care for back problems, parity, exercise and smoking habits, and occupation. RESULTS: The questionnaire was returned by 84.7% of the women. There was a significant, albeit weak, positive association between current use of hormone replacement treatment and low back pain. Previous back problems during pregnancy was a strong risk factor for current back pain, whereas neither current smoking nor regular physical exercise was a risk factor according to multiple logistic regression analysis. The interaction of smoking and an occupation involving heavy lifting significantly affected back pain. CONCLUSIONS: Women receiving hormone replacement treatment had a slightly, but significantly, higher prevalence of current back pain than nonusers (48% vs. 42%, respectively, P < 0.05), which could not be explained by differences in occupation, smoking habits, or current physical activity. Although the association between hormone replacement therapy and back problems is weak and probably of minor clinical importance, it is speculated that hormonal effects on joints and ligaments may be involved. 相似文献
43.
Dr.-Ing. A. Dittrich 《Electrical Engineering (Archiv fur Elektrotechnik)》1992,75(5):321-326
Übersicht Der feldorientierte Betrieb der Asynchronmaschine erlaubt die entkoppelte Einprägung von Moment und Fluß. Die Führung des Flusses sollte so erfolgen, daß an jedem Betriebspunkt das größtmögliche stationäre Moment erreicht werden kann. Es werden für begrenzten und unbegrenzten Ständerstrom Näherungslösungen entwickelt, die die benötigten Flußsteuergesetze in geschlossener Form zur Verfügung stellen und eine gute Übereinstimmung mit den Optimallösungen zeigen.
Torque optimal flux control of field-oriented induction machines in the field weakening range
Contents The principle of field orientation allows the decoupled control of torque and flux of induction machines. The flux should be forced in a way that provides the maximum stationary torque in each working point. In the paper approximated analytical solutions of the required control laws are presented. These control laws derived for limited and unlimited stator current show a good correspondence with the optimal solutions.相似文献
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We investigate several evolutionary computation approaches as a mechanism to “program” networks of excitable chemical droplets. For this kind of systems, we assigned a specific task and concentrated on the characteristics of signals representing symbols. Given a Boolean function as target functionality, 2D networks composed of 10 × 10 droplets were considered in our simulations. Three different set-ups were tested: Evolving network structures with fixed on/off rate coding signals, co-evolution of networks and signals, and network evolution with fixed but pre-evolved signals. Evolutionary computation served in this work not only for designing droplet networks and input signals but also to estimate the quality of a symbol representation: we assume that a signal leading to faster evolution of a successful network for a given task is better suited for the droplet computing infrastructure. Results show that complicated functions like XOR can evolve using only rate coding and simple droplet types, while other functions involving negations like the NAND or the XNOR function evolved slower using rate coding. Furthermore we discovered symbol representations that performed better than the straight forward on/off rate coding signals for the XNOR and AND Boolean functions. We conclude that our approach is suitable for the exploration of signal encoding in networks of excitable droplets. 相似文献
47.
Maltaris T Beckmann MW Binder H Mueller A Hoffmann I Koelbl H Dittrich R 《Reproduction (Cambridge, England)》2007,133(2):503-509
This prospective study compares the effect of a GnRH agonist on the number of follicles in different developmental stages in cryopreserved human ovarian grafts transplanted into gonadotropin-stimulated or not stimulated severe combined immunodeficient mice (SCID mice). Human ovarian tissue from seven patients was cryopreserved with an open-freezing system and xenotransplanted in SCID mice. The SCID mice were then treated according to different stimulation protocols. The survival of the tissue after cryopreservation was examined by LIVE/DEAD viability staining or transplanted in the neck muscle of 41 SCID mice. Development of follicles, estradiol production, vaginal cytology, and uterus weight were assessed after 15 weeks with or without gonadotropin stimulation. Viable follicles were detected in all frozen/thawed specimens using the LIVE/DEAD assay. Triptorelin, a GnRH agonist, caused a significant reduction of follicles in all developmental stages in the non-gonadotropin-stimulated animals (P<0.001). In gonadotropin-stimulated animals, GnRH agonist treatment has no significant effect on primordial, primary and preantral follicle count, whereas the antral follicles were significantly fewer (P = 0.03). The GnRH agonist treatment is not able to prevent the primordial follicle depletion after the xenografting of ovarian tissue in SCID mice with or without gonadotropin stimulation. Furthermore, it causes an additional loss of follicles if administered during the critical neovascularization period after the transplantation. 相似文献
48.
Constanze Hartmann Sébastien Doucet Yvan Niclass Ralf Dittrich Susanne Cupisti Benoist Schaal Andrea Buettner Christian Starkenmann 《Food chemistry》2012
Using ultra performance liquid chromatography–mass spectrometry we identified for the first time glutamine-N-α-conjugates of the fatty acids (E)/(Z)-3-methylhex-2-enoic acid and (R)/(S)-3-hydroxy-3-methylhexanoic acid as well as cysteinylglycine-S-conjugates of (R)/(S)-3-methyl-3-sulphanylhexan-1-ol and (R)/(S)-3-sulphanylhexan-1-ol as constituents of human milk and colostrum. The glutamine-N-α-conjugates were detected also in human amniotic fluids. The mean values of glutamine-N-α-conjugate of (R)/(S)-3-hydroxy-3-methylhexanoic acid were highest in colostrums with a range of <0.1–382 μg/kg, followed by the mature human milk with values from <0.1 to 39.6 μg/kg for defatted milk, and 0.8–7.0 μg/kg in amniotic fluids. The cysteinylglycine-S-conjugate of (R)/(S)-3-methyl-3-sulphanylhexan-1-ol were detected in the range of 2–24 ng/kg in human milk, and 7–101 ng/kg in colostrums. Our data demonstrate that concentrations in human milk vary between individuals, and with lactation period as the mean concentrations of the glutamine conjugates in colostrums were elevated in comparison to mature milk and the concentrations of acid precursors were close to 10 times higher. Further, these precursors were not detected in cow milk. 相似文献
49.
The benefit of using a hot sodium perborate solution, as well as hot-water rinsing, as a stabilizing treatment in the reductive setting of wool carpet yarn is minimal. Using a tape scouring machine, yarn should be treated with a solution prepared from sodium metabisulphite and adjusted to pH 7, followed by thorough rinsing with hot water, to set the twist. A bisulphite solution of pH 6 has poor pH stability at 85d?C, but at pH 7 the pH is stable for at least 5 h. The bisulphite concentration decreases with time at both pH values at this temperature. The use of alternatives to sodium metabisulphite, e.g. monoethanolamine sulphite, needs careful consideration on a cost-benefit basis. On a basis of equal SO2 content, the degree of set is similar with various compounds. 相似文献
50.
Degradation of Microcellular PLGA‐PEG Copolymer for Use in a Drug Delivery System for the Urinary Bladder
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