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91.
This experimental study analysed the effects of the complexity (entropy) of a repetitive tusk on the human looming function for the task. The results from 20 subjects revealed that the task entropy had a significant influence on the relationship between the performance (cycle time) and practice (the number of repetitions or cycle number). The model parameters for this relationship were found to be significantly and linearly related to the task entropy, the nominal rate of which varied within the maximum range of 0·9·to 6.1 bits/s  相似文献   
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PURPOSE: To understand the molecular mechanisms involved in protein-methylidene malonate 2.1.2 polymer interactions. METHODS: To assess the importance of electrostatic forces in polymer-protein interactions use was made of HSA and its derivatives, which were anionized by succinylation and aconitylation. Surface plasmon resonance measurements, using the three HSA molecules as immobilized ligands and polymer nanoparticles as analytes in the liquid phase, allowed the determination of initial kinetic constants and affinity constants at equilibrium at two different temperatures. RESULTS: Saturation of binding for the three proteins occurred at approximately 900 protein molecules/nanoparticle. The apparent affinity decreased with increasing electronegativity of the proteins. Surface plasmon resonance measurement of proteins, covalently linked to the chip matrix, showed a high affinity for the nanoparticles (K(A) approximately 10(10) M(-1) and confirmed the moderate decrease of affinity with increasing electronegativity of the modified albumins. Measurements at 25 and 37 degrees C showed no significant increase in the albumin-nanoparticle interactions. Dissociation of the proteins from the nanoparticles could only be realized with chaotropic salt solutions. CONCLUSIONS: These results suggest the molecular forces initiating the protein-nanoparticle interactions are mainly of electrostatic nature followed by stabilization by hydrophobic forces. The high affinity confirms the nanoparticles as excellent carriers for protein delivery.  相似文献   
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Nephroblastoma (Wilms' tumor) is the most common renal malignancy in childhood. Extrarenal Wilms' tumor is uncommon, and the diagnosis is almost always postsurgical. The authors report two cases, located in the sigmoid mesocolon, one of these having an associated horseshoe kidney. Both were treated with excision followed by chemotherapy. They are now 36 months and 7 months postchemotherapy, respectively, and are symptom and recurrence free. Both had favorable histological findings. Association with a horseshoe kidney raises an important issue regarding the histogenesis of these tumors. The authors believe that there is a nexus between the fusion of metanephric blastema during the sixth to seventh week of intrauterine life and the "ectopic" metanephric blastema cells that may give rise to extrarenal Wilms' tumor. Association with a horseshoe kidney with an extrarenal Wilms' tumor has been reported on five previous occasions. The authors closely examine the link between the two.  相似文献   
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Cartilage has an extremely poor capacity to heal, which has lead to intensive research into biomaterials and tissue engineering for the purpose of regenerating cartilage in vivo. Many of these techniques have shown great promise in vitro; however, the results do not always carry across to the in-vivo scenario. Healthy cartilage autografts often do not integrate with the adjacent cartilage, suggesting that cartilage is rarely capable of healing even under ideal conditions. It is hypothesized in this study that the surgical creation of defects in cartilage causes significant damage to the adjacent tissues, leading to further degradation of the cartilage and poor outcome for the repair in general. This study compares the healing response of osteochondral defects created with either a punch or a drill in the weight-bearing region of the sheep knee at 4 and 26 weeks following surgery. The use of a drill to create the defect creates a more aggressive inflammatory response at 4 weeks compared with a punch. However, by 26 weeks, defects created with a punch scored higher on the O'Driscoll cartilage grading scale. Tissue damage at the time of surgery plays an important part in the sequence of events for healing of cartilage defects. This knowledge will help to characterize and refine the ovine model for cartilage regeneration and may have an influence on surgical technique and instrumentation for clinical cartilage repair.  相似文献   
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Cyclobenzaprine (CBP) has a cyclic structure similar to amitriptyline. In overdose, CBP has been suggested to produce the cardiovascular and neurologic toxicity found with the cyclic antidepressants. To examine this possibility, a retrospective chart review of all cases of CBP exposure reported to five regional poison centers was performed for the years 1989-93. There were a total of 750 charts identified for CBP exposure, of which 523 had data sufficient for evaluation. There were 121 polydrug ingestions leaving 402 pure CBP ingestions. Ages ranged from 7 mo to 77 yrs, with a mean of 20 yrs; 26% were 6 yrs or less. Females comprised 63% of the patient group. No deaths occurred. Dysrhythmias beyond sinus tachycardia were infrequent, and none were life-threatening. No seizures occurred. Common effects were lethargy, sinus tachycardia, and agitation, and both hypertension and hypotension were seen. All symptomatic cases with a known time of ingestion were symptomatic within 4 h of ingestion. Doses ingested ranged from 5-1000 mg, with a mean of 133 mg. Asymptomatic and symptomatic patients had a mean dose ingested of 45 mg and 183 mg, respectively. Treatment was primarily gastrointestinal (GI) decontamination and supportive care. Other therapies required were mechanical ventilation, dopamine, fluid bolus, sedation, and foley catheter. Symptoms requiring treatment beyond GI decontamination did not occur with ingestions less than 100 mg. In conclusion, cyclobenzaprine does not appear to produce the life-threatening cardiovascular or neurologic effects of the cyclic antidepressants in doses less than 1 g. Lethargy and anticholinergic effects are prominent, though serious toxicity is infrequent.  相似文献   
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