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801.
LL Lautens XG Chiou JD Sharp WS Young DL Sprague LS Ross CC Felder 《Canadian Metallurgical Quarterly》1998,809(1):18-30
Children (aged 4 and 7 years) and young adults produced a six-syllable utterance 15 times. The displacement of the lower lip was recorded with an Optotrak system and analyzed in a number of ways. First, using a procedure recently developed in our laboratory, displacement records from the 15 repetitions were amplitude- and time-normalized, and the spatiotemporal index (the STI) was computed. The STI reflects the degree to which repeated performance of a task produces movement trajectories that converge on a single pattern. Children produced less stable movement trajectories, as reflected in higher values on the STI. In a second analysis, standard measurements of amplitude and peak velocity were made for two opening and two closing lip movements. These measures suggested that, relative to the size of their oral structures, children have large movement ranges in speech. Also, children tend to move with a lower peak velocity. This large-amplitude, low-velocity movement style may reflect different underlying control processes. Finally, another analysis focused on open-close movement sequences associated with two words of the utterance. A pattern-recognition algorithm applied to the normalized waveforms from the open-close sequences revealed that children and adults produced equally distinctive movement trajectories for the two syllables. Taken together, these preliminary results suggest that nonlinear and nonuniform changes occur in components of the speech motor system during development. 相似文献
802.
H Chen CB Baron T Griffiths P Greeley RF Coburn 《Canadian Metallurgical Quarterly》1998,177(1):161-173
Degenerative changes of the spinal column have long been and continue to be confused with the presence of spinal distress and pain. All parts of the spine undergo degenerative changes as we age. The purpose of this chapter is to describe the degenerative process and its clinical consequences. The disc degenerative process will be discussed; its consequences on the facet joint and osteophyte formation are considered. The prevalence of disc degeneration, the role of physically demanding work and leisure and the interference of spinal deformity is clarified. A section particularly important for the clinician deals with the clinical consequences of the degenerative process in disc herniation, degenerative spondylolisthesis, spondylolysis and stenosis. This chapter tries to put the degenerative changes of the spine into the context of a normal ageing process. 相似文献
803.
BACKGROUND: Major depression is associated with increased mortality, but it is not known whether patients who report depressive symptoms have greater mortality. SUBJECTS AND METHODS: We performed a prospective cohort study of 7518 white women 67 years of age or older who were recruited from population-based listings in Baltimore, Md, Minneapolis, Minn, Portland, Ore, and the Monongahela Valley, Pa. Participants completed the Geriatric Depression Scale (short form) and were considered depressed if they reported 6 or more of 15 possible symptoms of depression. Women were followed up for an average of 6 years. If a participant died, we obtained a copy of the official death certificate and hospital records, if available, and used International Classification of Diseases, Ninth Revision, codes to classify death attributable to cardiovascular, cancer, or noncancer, noncardiovascular cause. RESULTS: Mortality during 7-year follow-up varied from 7% in women with no depressive symptoms to 17% in those with 3 to 5 symptoms to 24% in those with 6 or more symptoms of depression (P<.001). Of 473 women (6.3%) with 6 or more depressive symptoms at baseline, 24% died (111 deaths in 2610 woman-years of follow-up) compared with 11% of women who reported 5 or fewer symptoms of depression (760 deaths in 41 460 woman-years of follow-up) (P<.001). Women with 6 or more depressive symptoms had a 2-fold increased risk of death (age-adjusted hazard ratio [HR], 2.14; 95% confidence interval [CI], 1.75-2.61; P<.001) compared with those who had 5 or fewer depressive symptoms. This association remained strong after adjusting for potential confounding variables, including history of myocardial infarction, stroke, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, smoking, perceived health, and cognitive function (HR, 1.47; 95% CI, 1.14-1.88; P=.003). Depressive symptoms were associated with an increased adjusted risk of death from cardiovascular diseases (HR, 1.8; 95% CI, 1.2-2.5; P= .003), and non-cancer, noncardiovascular diseases (HR, 1.8; 95% CI, 1.2-2.7; P = .01), but were not associated with deaths from cancer (HR, 1.0; 95% CI, 0.6-1.7; P=.93). CONCLUSIONS: Depressive symptoms are a significant risk factor for cardiovascular and noncancer, noncardiovascular mortality but not cancer mortality in older women. Whether depressive symptoms are a marker for, or a cause of, life-threatening conditions remains to be determined. 相似文献
804.
AM Settles A Yonetani A Baron DR Bush K Cline R Martienssen 《Canadian Metallurgical Quarterly》1997,278(5342):1467-1470
The bacterial Sec and signal recognition particle (ffh-dependent) protein translocation mechanisms are conserved between prokaryotes and higher plant chloroplasts. A third translocation mechanism in chloroplasts [the proton concentration difference (DeltapH) pathway] was previously thought to be unique. The hcf106 mutation of maize disrupts the localization of proteins transported through this DeltapH pathway in isolated chloroplasts. The Hcf106 gene encodes a receptor-like thylakoid membrane protein, which shows homology to open reading frames from all completely sequenced bacterial genomes, which suggests that the DeltapH pathway has been conserved since the endosymbiotic origin of chloroplasts. Thus, the third protein translocation pathway, of which HCF106 is a component, is found in both bacteria and plants. 相似文献
805.
Generally, it is preferable to tocolyze patients with idiopathic preterm labor (PTL). Little information is available about ultimate outcomes after successful tocolysis. Our objective is to evaluate the relationship between cervical change after the initiation of tocolysis and the delay in time to delivery in patients with preterm labor. A historical analysis of all patients with successful tocolysis after PTL between January 1992 and December 1993 was undertaken. The patients were then placed in one of three categories (regression, unchanged, or progression) based on cervical change after the initiation of tocolysis. Various demographic pregnancy characteristics and pregnancy outcome data were analyzed. One hundred and twenty-six patients had successful tocolysis and met the admission criteria. Patients who had cervical progression had shorter delay to delivery, delivered at an earlier gestational age (31.7 weeks compared to 34.0 and 34.1 weeks, respectively, p < 0.05), and were more likely to deliver before 35 weeks (88% compared to 50.0 and 55.0%, respectively, p < 0.05). Also, neonates remained in the hospital longer and were more likely to have respiratory distress syndrome when compared to the other two groups. Patients who had cervical progression after the initiation of tocolysis are more likely to deliver prematurely, had a shorter delay to delivery, and delivered lower birth weight infants than did patients whose cervix regressed or remained unchanged. In our population, patients who had successful tocolysis had a preterm delivery rate of 59.5% before the 35th week of gestation. 相似文献
806.
WS Joseph 《Canadian Metallurgical Quarterly》1997,87(11):520-531
The author discusses the new oral antifungal agents for the treatment of onychomycosis. The history, mechanisms of action, efficacies, dosing, safety profiles, and costs of itraconazole, terbinafine, and fluconazole are reviewed. The author emphasizes that use of these effective antifungals represents an important paradigm shift for podiatric physicians away from the palliative therapy of nail debridement to a potentially curative treatment. 相似文献
807.
JM Hare SK Shernan SC Body E Graydon WS Colucci GS Couper 《Canadian Metallurgical Quarterly》1997,95(9):2250-2253
BACKGROUND: In patients with left ventricular (LV) dysfunction, inhaled nitric oxide (NO) decreases pulmonary vascular resistance (PVR) but causes a potentially clinically significant increase in left atrial pressure (LAP). This has led to the suggestion that inhaled NO may reach the coronary circulation and have a negative inotropic effect. This study tested an alternative hypothesis that LAP increases because of volume shifts to the pulmonary venous compartment caused by NO-induced selective pulmonary vasodilation. METHODS AND RESULTS: The Thermo Cardiosystems Heartmate is an LV assist device (LVAD) that can be set (by controlling pump rate) to deliver fixed or variable systemic blood flow. Eight patients (between 1 and 11 days after LVAD implantation) were administered inhaled NO (20 and 40 ppm for 10 minutes), and LAP, systemic flow, and pulmonary arterial pressure were measured in both fixed and variable pump flow modes. In both modes, inhaled NO lowered PVR (by 25 +/- 6% in the fixed mode, P < .001, and by 21 +/- 5% in the variable mode, P < .003). With fixed pump flow, LAP rose from 12.5 +/- 1.2 to 15.1 +/- 1.4 mm Hg (P < .008). In the variable flow mode, LAP did not increase and the assist device output rose from 5.3 +/- 0.3 to 5.7 +/- 0.3 L/min (P < .008). CONCLUSIONS: A selective reduction in PVR by inhaled NO can increase LAP if systemic flow cannot increase. These data support the hypothesis that with LV failure, inhaled NO increases LAP by increasing pulmonary venous volume and demonstrate that inhaled NO has beneficial hemodynamic effects in LVAD patients. 相似文献
808.
The anteroposterior axis of the developing embryo becomes morphologically apparent at the onset of gastrulation with the formation of the primitive streak. This structure, where the first mesodermal cells arise, marks the posterior aspect of the embryo. To examine the potential role of non-mesodermal signals in specifying posterior (hematopoietic and endothelial) cell fates in the mouse embryo, we have devised a transgenic explant culture system. We show that interactions between primitive endoderm and adjacent embryonic ectoderm or nascent mesoderm are required early in gastrulation for initiation of hematopoiesis and vasculogenesis. Surprisingly, primitive endoderm signals can respecify anterior (prospective neural) ectoderm to a posterior mesodermal fate, resulting in formation of blood and activation of endothelial markers. Reprogramming of anterior ectoderm does not require cell contact and is effected by stage-dependent, short-range, diffusible signal(s). Therefore, primitive endoderm signaling is a critical early determinant of hematopoietic and vascular development and plays a decisive role in anterior-posterior patterning during mouse embryogenesis. 相似文献
809.
TD Doerr JK Dziadziola DA Komjathy DL Burgio WS Quirk 《Canadian Metallurgical Quarterly》1998,255(8):385-390
Several authors have proposed that complications arising from vestibular disorders are the result of compromised circulation. The purpose of the current study was to assess the ability of flunarizine and pentoxifylline to increase peripheral vestibular blood flow (VBF), since flunarizine is a selective calcium-channel entry blocker that inhibits calcium-related contraction of smooth muscle, while pentoxifylline is a xanthine derivative that promotes microcirculation by affecting red blood cell malleability. Both of these treatment strategies have received considerable attention in clinics and laboratory, but their effects on blood flow are unclear. Changes in VBF were evaluated from the posterior semicircular canal ampulla in guinea pigs using a laser Doppler flowmeter. One group of animals was infused with pentoxifylline at concentrations of 10-40 mg/ml, while a second group was treated with 0.3-1.5 mg/kg flunarizine. VBF, blood pressure (BP) and heart rate (HR) were monitored continuously. Findings showed that pentoxifylline induced a concentration-dependent increase in VBF. In contrast, no increase in VBF occurred in response to flunarizine infusions. These studies suggest that the effectiveness of pentoxifylline in the clinical treatment of vestibular disorders may be the result of improved blood flow. 相似文献
810.
MC Hu WR Qiu YP Wang D Hill BD Ring S Scully B Bolon M DeRose R Luethy WS Simonet T Arakawa DM Danilenko 《Canadian Metallurgical Quarterly》1998,18(10):6063-6074
The fibroblast growth factors (FGFs) play key roles in controlling tissue growth, morphogenesis, and repair in animals. We have cloned a novel member of the FGF family, designated FGF-18, that is expressed primarily in the lungs and kidneys and at lower levels in the heart, testes, spleen, skeletal muscle, and brain. Sequence comparison indicates that FGF-18 is highly conserved between humans and mice and is most homologous to FGF-8 among the FGF family members. FGF-18 has a typical signal sequence and was glycosylated and secreted when it was transfected into 293-EBNA cells. Recombinant murine FGF-18 protein (rMuFGF-18) stimulated proliferation in the fibroblast cell line NIH 3T3 in vitro in a heparan sulfate-dependent manner. To examine its biological activity in vivo, rMuFGF-18 was injected into normal mice and ectopically overexpressed in transgenic mice by using a liver-specific promoter. Injection of rMuFGF-18 induced proliferation in a wide variety of tissues, including tissues of both epithelial and mesenchymal origin. The two tissues which appeared to be the primary targets of FGF-18 were the liver and small intestine, both of which exhibited histologic evidence of proliferation and showed significant gains in organ weight following 7 (sometimes 3) days of FGF-18 treatment. Transgenic mice that overexpressed FGF-18 in the liver also exhibited an increase in liver weight and hepatocellular proliferation. These results suggest that FGF-18 is a pleiotropic growth factor that stimulates proliferation in a number of tissues, most notably the liver and small intestine. 相似文献