Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our previous data demonstrated that both 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium ion (MPP+) exerted potent inhibition on endogenous 3,4-dihydroxyphenylacetic acid (DOPAC) output and potent stimulation on endogenous dopamine (DA) release from the rat corpus striatum superfused in vitro. In this report, using a push-pull perfusion technique, we examined in vivo the acute effects of MPTP and MPP+ on DA metabolism in the rat caudate nucleus (CN). MPTP or MPP+ in modified Krebs-Ringer phosphate buffer at concentrations of 10(-6), 10(-5) and 10(-4) M was administered directly into the CN for 15 min, each 90 min apart. Thirty minutes after the infusion of 10(-6) M MPP+, DOPAC output was reduced to a significantly lower value and subsequent infusions of high concentrations of MPP+ further decreased DOPAC output. Homovanillic acid (HVA) output was also decreased by MPP+ infusions, however, at higher concentrations. In respect to DA release, 1 of 10, 4 of 10 and 7 of 10 animals responded with significant increases to 10(-6), 10(-5) and 10(-4) M MPP+, respectively. On the other hand, MPTP was effective in reducing DOPAC output only at 10(-4) M and ineffective in altering DA and HVA output at all doses tested. In addition, neither drugs had a significant effect on 5-hydroxyindoleacetic acid. Accompanying the dramatic changes in DA metabolism caused by MPP+, two uncommon behavioral syndromes were also observed; tremor-body twist and body shaking.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects on dopamine metabolism of MPTP and MPP+ infused through a push-pull cannula into the caudate nucleus of awake adult male rats. 331 41

This article reports the use of simple beam and finite-element models to investigate the relationship between rostral shape and biomechanical performance in living crocodilians under a range of loading conditions. Load cases corresponded to simple biting, lateral head shaking, and twist feeding behaviors. The six specimens were chosen to reflect, as far as possible, the full range of rostral shape in living crocodilians: a juvenile Caiman crocodilus, subadult Alligator mississippiensis and Crocodylus johnstoni, and adult Caiman crocodilus, Melanosuchus niger, and Paleosuchus palpebrosus. The simple beam models were generated using morphometric landmarks from each specimen. Three of the finite-element models, the A. mississippiensis, juvenile Caiman crocodilus, and the Crocodylus johnstoni, were based on CT scan data from respective specimens, but these data were not available for the other models and so these--the adult Caiman crocodilus, M. niger, and P. palpebrosus--were generated by morphing the juvenile Caiman crocodilus mesh with reference to three-dimensional linear distance measured from specimens. Comparison of the mechanical performance of the six finite-element models essentially matched results of the simple beam models: relatively tall skulls performed best under vertical loading and tall and wide skulls performed best under torsional loading. The widely held assumption that the platyrostral (dorsoventrally flattened) crocodilian skull is optimized for torsional loading was not supported by either simple beam theory models or finite-element modeling. Rather than being purely optimized against loads encountered while subduing and processing food, the shape of the crocodilian rostrum may be significantly affected by the hydrodynamic constraints of catching agile aquatic prey. This observation has important implications for our understanding of biomechanics in crocodilians and other aquatic reptiles.
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PMID:Biomechanics of the rostrum in crocodilians: a comparative analysis using finite-element modeling. 1683 25

A method is presented for data-driven calibration of the magnetometer in an active handheld microsurgical instrument in the presence of a surgical microscope. The instrument is designed to provide tremor compensation during vitreoretinal microsurgery. An adaptive-network-based fuzzy inference system is used to generate a calibration based on data points collected at random locations throughout the workspace. Inputs to the model include the tilt angle and the twist angle about the long axis of the instrument, obtained from accelerometer readings, and the azimuth of the apparent magnetic north, obtained from the magnetometer readings. The model outputs the true azimuth angle of the instrument. Results from preliminary testing of the method are presented.
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PMID:Fuzzy calibration of magnetometer in presence of surgical microscope. 1728 80

A new class of homologous gelators, LG12 -(CH2 )n -BSA, composed of bipyridinyl groups, L-glutamic moieties having double dodecyl chains, and linked alkyl spacers with different lengths were synthesized. It was found that these gelators could immobilize medium-polarity solvents readily and the behaviors of these gels showed a dependence on the spacer length. Of all the gels, the LG12 -(CH2 )11 -BSA gels exhibited self-healing property and multiple-stimulus responsibility, such as heating, shaking, and sonication. The investigation of CD spectra indicated that the supramolecular chirality, which was attributed to the chiral transfer from the chiral center to the assemblies, was also closely related to the length of methylene spacers. The longer the alkyl spacers, the weaker the transmitted supramolecular chirality. Only LG12 -(CH2 )1 -BSA gelators, which had the shortest spacers, formed right-handed nanoscale chiral twists owing to crowded hydrogen bonding interactions. Moreover, the high-polarity solvent DMF was found to be able to regulate the chiral twist as well as its pitch length readily.
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PMID:Multiple-stimulus-responsive supramolecular gels and regulation of chiral twists: the effect of spacer length. 2583 65