Scoliosis prevalence: a call for a statement of terms

Recently published prevalence studies of scoliosis reveal a disconcerting variability, largely due to the use of different diagnostic "cutting points", which are frequently unstated. A statistical analysis of the prevalence of moderate and severe scoliotic curves shows that the distribution of scoliotic curves conforms best to a log normal distribution. Using this analysis, and using 10 degrees as the "cutting point" for the diagnosis, the adolescent scoliosis population consists of approximately 25 per 1,000.     

The assessment of professional competence

Valid assessment of professional competence has proven to be an elusive goal. Objective tests, direct observation of performance, overall ratings of competence, and simulations have been tried and found wanting in one way or another. Objective test items are criticized as being unrealistic and therefore invalid. Direct observation tends to be very unreliable and therefore invalid. Simulations and overall ratings of competence share both of these flaws to some extent. Basically, you can't win. This article outlines some of the many ways to lose and some ways to cut these losses. In doing so, it proposes a general framework for evaluating the validity of measures of competence, and it uses this framework to examine the strengths and weaknesses of three approaches to the assessment of professional competence: direct observation, simulation, and objective testing.     

Approaches to evaluating the toxicity and carcinogenicity of man-made fibers: summary of a workshop held November 11-13, 1991, Durham, North Carolina.

The Workshop on Approaches to Evaluating the Toxicity and Carcinogenicity of Man-Made Fibers (MMF) was held in Durham, North Carolina, on November 11-13, 1991. The goal of the workshop was to reach a consensus, or to determine the extent to which a consensus existed, in two areas. Participants were asked to identify scientifically sound approaches for evaluating the toxicity and carcinogenicity of man-made fibers based on today's science and to determine research appropriate for study during the next 5 years that can provide an improved scientific basis for future revisions of approaches used to evaluate man-made fiber toxicity and carcinogenicity. During the first day, a series of "state of knowledge" presentations were made to provide all participants with a common data base from which to interact and discuss scientific issues. The workshop participants were assigned to one of four discussion groups, which met separately in three half-day sessions following the first day of presentations. All groups discussed the same topics: exposure assessment, hazard identification, and dose-response information needed to integrate to characterize risk in the first session; approaches to obtaining the needed information in the second session; and recommended approaches and guidelines for evaluating the toxicity and carcinogenicity of MMF and research needs in the third session. The workshop participants reconvened as a whole after each discussion session, and one member from each group reported the group's conclusions. A closure period was also included at the end of the workshop for review and discussion of items that had been considered during the workshop. The primary conclusions reached were the following: -All fiber types capable of depositing in the thorax are not alike in their pathogenic potential. -Only fiber samples with dimensions similar to those to which humans can inhale should be tested. -A complete characterization (i.e., dimensions, fiber number, mass, and aerodynamic diameter) of the fiber aerosol and retained dose is essential. -Appropriate aerosol generation methods must be used for inhalation studies in order to preserve fiber lengths. -A tiered approach to toxicity evaluation is recommended that includes: 1. In vitro screening for durability, surface properties, cytotoxicity, and similar properties, etc; 2. Short-term inhalation or other in vivo studies; 3. That chronic inhalation studies are the "gold standard" (i.e., provide most appropriate data for risk characterization). -The rat is the most appropriate species for inhalation studies. -In chronic inhalation studies, animals should be retained to at least 20% survival after 2-year exposure. -Serial lung burden analyses are an essential component of inhalation studies and are essential for understanding exposure-dose-response relationships. -Studies oriented to understanding mechanisms of toxicity and carcinogenicity are important adjuncts to traditional toxicity studies. -Histopathological analyses of tissues of the respiratory tract represent primary endpoints for evaluating effects of inhaled fibers. Major effects include pulmonary fibrosis, lung tumors, and mesotheliomas. Experimental tissues should be archived for future studies; wherever possible, handling and preservation of tissues should be done in a way that maximizes their future use in mechanistic studies. -Potential human exposures throughout the entire life-cycle of the fiber must be considered and fibrous material for toxicologic studies prepared accordingly. -Intracavity studies are inappropriate for risk characterization but can play a useful screening role in assessing fiber toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Exogenous beta 2-microglobulin is required for antigenic peptide binding to isolated class I major histocompatibility complex molecules

Binding of antigenic peptides to purified class I major histocompatibility complex (MHC) molecules, as measured by antigen-specific cytolytic T lymphocyte (CTL) degranulation, was found to occur in the presence of serum but not in its absence. The role of soluble beta 2-microglobulin (beta 2m), a normal component of serum, in class I-peptide complex formation was therefore examined. Sera depleted of beta 2m did not support effective peptide binding to class I, but binding was restored in the presence of low concentrations of purified human beta 2m. Sequential incubation of immobilized class I with human beta 2m first, followed by peptide, resulted in antigenic complex formation, while reversing the order of pulsing could not. Similar results were obtained in experiments examining H-2Db, Kb and Kd with appropriate peptides and CTL. These results demonstrate that mature class I proteins are not able to directly bind peptide, but that interaction with exogenous beta 2m results in a structure that will subsequently bind peptide. Binding of exogenous beta 2m appears to result in "empty" class I molecules, possibly by exchange for endogenous beta 2m, with a concomitant loss of endogenous peptide.     

Analysis of a modified active knee extension test

When this study was conducted, the authors were pursuing Master of Science degrees in physical therapy, orthopaedic and sports medicine, at the MGH Institute of Health Professions, Boston, MA. Hamstring injuries occur and reoccur at high rates in the athletic population. The purpose of this study was to describe the effect of contralateral hip flexion on pelvic rotation in the sagittal plane and ipsilateral active knee extension during a modified active knee extension test. Twenty-seven normal subjects were tested, yielding 54 sets of data. Active knee extension was performed in five positions of contralateral hip flexion and was videotaped. Measurements of pelvic and knee joint angles were obtained from the film. The results indicated the least amount of pelvic rotation was 5.5 degrees , which occurred at maximum contralateral hip flexion. Analysis of variance revealed a difference between test positions that was statistically significant for pelvic rotation and knee extension (p < .05). Pelvic rotation can be effectively controlled during an active knee extension test by maximally flexing the contralateral hip. The active knee extension test can be used as an accurate assessment tool to evaluate hamstring muscle length. J Orthop Sports Phys Ther 1992;15(3):141-146.     

Contraception in China

Family planning has become general practice and a voluntary action by the majority of the Chinese people. A survey of contraceptive attitudes of people from street committees to the factory or commune revolutionary committees indicated that the most popular method of contraception is the low-dose oral contraceptive. Sterilization, although viewed as a crude solution, is a widely used alternative (30 percent male, 70 percent female). Other methods employed include the "paper pill," an experimental once-a-month pill, and injectables. The c oncept of late marriage and child spacing is encouraged. Group pressure persuading young people within the group to defer marriage and requirements establishing that candidates for further training should be unmarried act as disincentives to rapid family growth. In addition, target birth plans made by each area in China realistically influence individuals concerning contraception.     

Synthesis of deuterium‐labeled 3‐O‐methyldopa and 4‐O‐methyldopa

Concise methods for the synthesis of 4‐hydroxy‐3‐[²H₃]‐methoxyphenylalanine (3‐O‐[²H₃]‐methydopa) and 3‐hydroxy‐4‐[²H₃]‐methoxyphenylalanine (4‐O‐[²H₃]‐methydopa) are described. The 3‐O‐[²H₃]‐methydopa is a valuable internal standard for the tandem MS quantification of 3‐O‐methyldopa, a metabolite of value in the diagnosis of aromatic l‐amino acid decarboxylase (AADC) deficiency. Copyright © 2003 John Wiley & Sons, Ltd.