Deformative stress associated with an abnormal clivo-axial angle: A finite element analysis.

BACKGROUND: Chiari malformation, functional cranial settling and subtle forms of basilar invagination result in biomechanical neuraxial stress, manifested by bulbar symptoms, myelopathy and headache or neck pain. Finite element analysis is a means of predicting stress due to load, deformity and strain. The authors postulate linkage between finite element analysis (FEA)-predicted biomechanical neuraxial stress and metrics of neurological function. METHODS: A prospective, Internal Review Board (IRB)-approved study examined a cohort of 5 children with Chiari I malformation or basilar invagination. Standardized outcome metrics were used. Patients underwent suboccipital decompression where indicated, open reduction of the abnormal clivo-axial angle or basilar invagination to correct ventral brainstem deformity, and stabilization/ fusion. FEA predictions of neuraxial preoperative and postoperative stress were correlated with clinical metrics. RESULTS: Mean follow-up was 32 months (range, 7-64). There were no operative complications. Paired t tests/ Wilcoxon signed-rank tests comparing preoperative and postoperative status were statistically significant for pain, bulbar symptoms, quality of life, function but not sensorimotor status. Clinical improvement paralleled reduction in predicted biomechanical neuraxial stress within the corticospinal tract, dorsal columns and nucleus solitarius. CONCLUSION: The results are concurrent with others, that normalization of the clivo-axial angle, fusion-stabilization is associated with clinical improvement. FEA computations are consistent with the notion that reduction of deformative stress results in clinical improvement. This pilot study supports further investigation in the relationship between biomechanical stress and central nervous system (CNS) function.

Webpage aesthetics, performance and usability: design variables and their effects.

The primary objectives of this research are to identify the underlying clusters of design variables affecting the perceived usability of a webpage and to examine the effects of webpage design variables on webpage performance. Fifty-seven design variables and 10 underlying clusters that conceptualise the structure of user webpage judgement are identified through content analysis on literature and structured interviews, balanced incomplete block user survey administration and cluster analysis. Five clusters are selected to conduct three experiments that quantify the change in user aesthetic preference, perceived ease of interaction and interaction speed as a function of loading speed, image colour, image size, font size, link style, and column width. Results show that user performance alone is not a good indicator of aesthetic judgement and overall effectiveness of a webpage. The value of integrating global construct analysis processes and local controlled experimentation processes in ergonomic interface research is illustrated. Fifty-seven webpage design variables are defined, ranked and clustered according to perceived importance and overall preference. Experimental results illustrate that both technical performance and aesthetic factors are important webpage design considerations.

Trends in cancer therapy: role of monoclonal antibodies.

OBJECTIVES: To discuss the scientific rationale for the use of monoclonal antibodies in cancer treatment and distinguish the unique characteristics of selected monoclonal antibodies. DATA SOURCES: Published scientific papers, abstracts, review articles, and book chapters. CONCLUSION: The continued discovery of intrinsic antigens/epitopes specific to malignant cells and the science of immune cell activation demonstrates the durability of monoclonal antibodies as mainstream immunotherapy. IMPLICATIONS FOR NURSING PRACTICE: With the success of monoclonal antibodies used in clinical practice, oncology nurses need to continue to increase their knowledge and competency. Monoclonal antibodies target tumor-associated antigens in both solid and hematologic tumors. It is imperative that nurses be familiar with specific aspects of each antibody infusion they administer.