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161.
Visual and mechanosensory development of three sciaenid species was investigated to examine possible correlations between sensory morphology and patterns of habitat use. Although the three species have different migration patterns as early larvae, few differences in sensory morphology occurred between species until late in the larval period. Atlantic croaker, Micropogonias undulatus, were distinguished by enhancements of visual morphology (large eyes, abundant photoreceptors, and best summation of the three species). Croaker arrive inshore later in the larval period and, after settlement, appear to use deeper water habitats than do the other two species. Spotted seatrout, Cynoscion nebulosus, had the fewest enhancements of visual morphology but had more free neuromasts than the other two species late in the larval period. After settlement, seatrout are primarily associated with seagrass habitats. Red drum, Sciaenops ocellatus, did not have pronounced specialization of one sensory system, as did the other two species. For part of the larval period, neuromast numbers were higher in red drum than in the other two species. Later, enhancements of visual morphology did occur, but only eye and lens size were the same as those of Atlantic croaker. Red drum larvae appear to use a wider variety of habitats than do the other two species. In none of the species examined did sensory changes correlate with offshore to inshore movements, and only initial rod formation occurred prior to settlement. Distinct sensory changes did not occur concurrent with habitat changes, probably due to constructional and phylogenetic constraints. Rather, sensory differences are related to the environmental conditions in the predominant inshore habitat occupied by each species after settlement, when morphological limitations are less severe. 相似文献
162.
KR Burgess 《Canadian Metallurgical Quarterly》1998,3(1):1-11
The three-dimensional (3-D) structure of a RNA pseudoknot that causes the efficient ribosomal frameshifting in the gag-pro region of mouse mammary tumor virus (MMTV) has been determined recently by nuclear magnetic resonance (NMR) studies. But since the structure refinement in the studies did not use metal ions and waters, it is not clear how metal ions participate in the stabilization of the pseudoknot, and what kind of ion-RNA interactions dominate in the tertiary contacts for the RNA pseudoknotting. Based on the reported structure data of the pseudoknot VPK of MMTV, we gradually refined the structure by restrained molecular dynamics (MD) using NMR distance restraints. Restrained MD simulation of the RNA pseudoknot was performed with sodium ions and water molecules. Our results are in good agreement with known NMR data and delineate the importance of the metal ion coordination in the stability of the pseudoknot. In the non-coaxially stacking pseudoknot, stem 1 (S1), stem 2 (S2), and the intervening A14 involves unconventional stacking of base pairs coordinated by Na+ and/or bridging water molecules. A6 and G7 of loop L1 make a perfect base stacking in the major groove and are further stabilized by coordinated Na+ ions and water molecules. The first 4-nucleotide (nt) ACUC of loop L2 form a sharp turn and the following 4-nt AAAA cross the minor groove of S1 and are steadied by interactions with the nucleotides of S , bridging water molecules and coordinated Na+ ions. Our studies suggest that the metal ion plays a crucial role in the RNA pseudoknotting of VPK. In the stacking interior of S1 and S2, the Na+ ion is positioned in the major groove and interacts directly with the carbonyl group O6 of G28 and carbonyl group O4 of U13 in the wobble base pair U13:G28. The ion-RNA interactions in MMTV VPK not only stabilize the RNA pseudoknot but also modify the electrostatic properties of the nucleotides at the critical parts of the pseudoknot VPK. 相似文献
163.
WD van Marken Lichtenbelt GA Heidendal KR Westerterp 《Canadian Metallurgical Quarterly》1997,51(12):826-830
OBJECTIVES: To assess sleeping metabolic rate (SMR), average daily metabolic rate (ADMR), and total bone mineral density (TBMD) in women with anorexia nervosa, and to evaluate the effect of daily physical activity on TBMD. DESIGN: We compared women with anorexia nervosa and controls using measurements on body composition, and energy expenditure. Relations between these measurements were investigated. SETTING: Daily living environments in The Netherlands, and body composition and energy expenditure laboratory of the Department of Human Biology. SUBJECTS: Twelve adult, non-hospitalized women with anorexia nervosa, and sixteen adult normal weight women. INTERVENTIONS: Average daily metabolic rate was measured with the doubly labeled water method and sleeping metabolic rate in a respiration chamber. TBMD was measured by dual energy X-ray absorptiometry, and percentage body fat was calculated combining the results from underwater weighing and deuterium dilution. RESULTS: TBMD was significantly lower in anorexia than in controls (0.989 +/- 0.081 vs 1.144 +/- 0.054 g/cm2). Also ADMR and SMR were reduced in anorexia. The physical activity index (PAI = ADMR/SMR) was not significantly different from PAI in controls. In anorexia, TBMD was related to the PAI (R2 = 0.35, P < 0.05). Finally, stepwise multiple regression revealed that PAI together with the study groups as dummy variables could explain 69% of the variation in TBMD. CONCLUSION: These findings show that in anorexia TBMD is reduced, but that nonetheless physical activity has a significant positive effect on bone density. 相似文献
164.
A McShea PL Harris KR Webster AF Wahl MA Smith 《Canadian Metallurgical Quarterly》1997,150(6):1933-1939
In this study, we demonstrate that two important regulators of the cell cycle, cyclin-dependent kinase-4 and its inhibitor p16, are increased in the brains of cases of Alzheimer's disease patients compared with age-matched controls. Both proteins are increased in the pyramidal neurons of the hippocampus, including those neurons containing neurofibrillary tangles and granulovacuolar degeneration. As p16 is not normally found in terminally differentiated neurons, it seems paradoxical that it is increased in Alzheimer's disease unless it is responding to increases in cyclin-dependent kinase-4 or other cell cycle regulators. Induction of the latter, a protein that signals re-entry and progression through the cell cycle, may itself be the consequence of alpha response to a growth stimulus. Re-entry into the cell cycle is likely deleterious in terminally differentiated neurons and may contribute to the biochemical abnormalities, such as oxidative stress and hyperphosphorylated tau protein, as well as the neuronal degeneration characteristic of the pathology of Alzheimer's disease. 相似文献
165.
Oxytocin analogues which combine high oxytocic activities with negligible antidiuretic and pressor activities have been studied. [4-Threonine,7-glycine]oxytocin, [1-(L-2-hydroxy-3-mercaptopropionic acid),4-threonine,7-glycine]oxytocin, and [1-(L-2-hydroxy-3-mercaptopropionic acid)]oxytocin were found to possess the following specific biological activities respectively: rat uterotonic, 270 +/- 10, 337 +/- 23, 1542 +/- 0.4; rat antidiuretic, 0.002 +/- 0.0008, 0.048 +/- 0.005, 40.3 +/- 2.4. The results are analyzed from a conformation-activity viewpoint in a continued attempt to evaluate the scope and limitations of this approach in comparison to structure-activity studies. 相似文献
166.
Richard Le Heron Glen W. Atkinson Henry Teune Greg Mason Henk Voogd Brenda J. Moscove Patricia Gober Thomas A. Reiner Richard F. Curtis Stephen F. Seninger W. W. Hall Jr. John E. Keith M. Van Naelten R. W. Keyes John Huttman Robert B. Weeden Clarence G. Ray Steven E. Daniels F. Larry Leistritz Patrizia Spinetti Peter D. Beaulieu F. J. Potgieter David L. Barkley Charles A. Berry Jean E. Weber Wieslaw Rozlucki Jesse Burkhead John R. Ottensmann Noel D. Uri Erlet Cater J. Barry Riddell Ernesto Quintanilla John F. McDonald Jon R. Miller Stan Czamanski 《The Annals of Regional Science》1986,20(1):87-144
167.
KR Cundiff 《Canadian Metallurgical Quarterly》1993,92(2):375-376
A 30-year-old woman, diagnosed as having systemic lupus erythematosus at the age of 18, presented with excessive sleepiness and cataplectic attacks. Sleep laboratory findings were consistent with narcolepsy. To the best of our knowledge an association between these 2 diseases has never been reported. The unrelated course of narcolepsy and lupus symptoms in our patient suggests a lack of common pathogenetic mechanisms and this association is more likely explained by genetic factors. 相似文献
168.
CF Durham KR Alden JA Dalton J Carlson DW Miller SP Englebardt VJ Neelon 《Canadian Metallurgical Quarterly》1998,38(6):427-435
Calcium phosphate bone cements (CPBCs) are osteotransductive, i.e. after implantation in bone they are transformed into new bone tissue. Furthermore, due to the fact that they are mouldable, their osteointegration is immediate. Their chemistry has been established previously. Some CPBCs contain amorphous calcium phosphate (ACP) and set by a sol-gel transition. The others are crystalline and can give as the reaction product dicalcium phosphate dihydrate (DCPD), calcium-deficient hydroxyapatite (CDHA), carbonated apatite (CA) or hydroxyapatite (HA). Mixed-type gypsum-DCPD cements are also described. In vivo rates of osteotransduction vary as follows: gypsum-DCPD > DCPD > CDHA approximately CA > HA. The osteotransduction of CDHA-type cements may be increased by adding dicalcium phosphate anhydrous (DCP) and/or CaCO3 to the cement powder. CPBCs can be used for healing of bone defects, bone augmentation and bone reconstruction. Incorporation of drugs like antibiotics and bone morphogenetic protein is envisaged. Load-bearing applications are allowed for CHDA-type, CA-type and HA-type CPBCs as they have a higher compressive strength than human trabecular bone (10 MPa). 相似文献
169.
M Canagaratna JA Phillips H Goodfriend DL Fiacco ME Ott B Harms KR Leopold 《Canadian Metallurgical Quarterly》1998,192(2):338-347
The effects of different doses of filgrastim on yields of CD34+ peripheral blood stem cells were evaluated in patients with breast cancer. 55 were randomized to receive filgrastim 10, 20, 30 or 40 microg/kg/d with more CD34+ cells/kg/apheresis harvested after the three highest dose levels. 35 additional patients were randomized to receive 10 or 30 microg/ kg. The median number of CD34+ cells collected after 10 microg/ kg (n = 31) was 0.7 x 10(6)/kg/apheresis (range 0.1-4.4) as compared to 1.2 (range 0.1-6.8) after 30 microg/kg (n = 32) (P = 0.04). Among patients randomized to 10 v 30 microg/kg, more (50%) achieved > or = 5.0 x 10(6) CD34+ cells/kg and less aphereses were required to achieve > or = 2.5 x 10(6) CD34+ cells/kg after the higher dose (P = 0.04). In multivariate analyses, patients receiving 10 microg/kg (n = 31) had lower yields of CD34+ cells (P = 0.026) and had a 3.3-fold increase in the probability of not achieving > or = 5.0 x 10(6) CD34+ cells/kg as compared to patients receiving 20-40 microg/kg (n = 59). Patients who had received radiation had a 2.9-fold probability of not achieving > or = 2.5 x 10(6) CD34+ cells/kg. These data suggest that, in patients with good marrow reserves, doses of filgrastim > 10 microg/kg/d mobilized more CD34+ cells and may be useful when high numbers of CD34+ cells are desired. 相似文献
170.