Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions

Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established.     

The histopathology of freezing injury to the rat spinal cord. A light microscope study. I. Early degenerative changes

In an effort to develop a method of tissue injury which would provide a model for the study of axonal regrowth in adult mammalian central nervous system (CNS), we have analyzed the effects of freezing in the dorsal columns of more than 200 rat spinal cords. The effects of temperature and time of exposure upon the size, shape, distribution and histologic characteristics of the lesion have been assessed during the first seven days following the injury. The upper threshold for injury occurs at -3 degrees C for 15 minutes. Between -3 degrees C and -12 degrees C the tissue changes vary in extent and characteristics. Selective damage to axons and myelin occurs with sparing of the supportive cells followed by proliferation of a cellular matrix. At seven days, the lesions produced by -8 degrees C for 15 to 60 minutes have neither axons nor myelin sheaths and consist of a dense cellular matrix of macrophages and presumed glial cells. With these tissue characteristics, and the preservation of tissue continuity without obstructive barriers, this model would appear to be potentially suitable for the study of axonal regrowth potential in mammalian CNS.     

Accuracy of women's recall of opportunistic recruitment for cervical cancer screening in general practice

Abstract: Evaluation of strategies to improve opportunistic recruitment via general practice of women overdue for a cervical smear requires an accurate behavioural measure. As part of an experimental trial to evaluate the effect of a postgraduate workshop on preventive care, we conducted this methodological study to determine the accuracy of women's recall of an opportunistic discussion about cervical screening, by comparing it against audiotapes ( n = 524). Taking the taped evidence of the trainee's verbal behaviour as the gold standard, sensitivity was 85 per cent (95 per cent confidence interval (CI) 73.1 to 92.0 per cent) and specificity was 78 per cent (CI 73.9 to 81.6 per cent). Given the low rate of opportunistic recruitment by trainees in the main study, only one–third of positive recollections by women of an opportunistic discussion about cervical screening were correct. Until other measures have been validated, women's recall may continue to be used to measure general practitioners' behaviour, but an appreciation of likely bias is recommended.     

Total synthesis of the four stereoisomers of dihexadecanoyl phosphatidylinositol and the substrate stereospecificity of human erythrocyte membrane phosphatidylinositol 4-kinase

A new and convenient method for the preparation of the four stereoisomers of dihexadecanoyl phosphatidylinositol has been developed. An enantiomeric pair of acid-labile, pentaprotected myo-inositol building blocks was synthesized in high yield and coupled with chiral phenyl dihexadecanoylglyceryl phosphates to give the fully protected phosphatidylinositols. These were subsequently deprotected by hydrogenolysis and self-hydrolysis in aqueous ethanol to give the desired pure products. Comparison of these compounds as potential substrates for a partially purified phosphatidylinositol 4-kinase (EC 2.7.1.67) derived from human erythrocyte membranes revealed that the chirality of the inositol ring is crucial for efficient phosphorylation, whereas the chirality of the glycerol moiety is relatively unimportant. Moreover, the similarity in phosphorylation rates of the naturally occurring mammalian phospholipid, I, and its synthetic stereochemical counterpart, compound 10a, suggests that the enzyme is relatively tolerant to changes in fatty acid composition.     

Using a supervisory framework to support and evaluate a multiproject practice development programme

? The paper describes a multiproject practice development programme undertaken over a period of 1 year. ? The background and development of the programme are outlined, whilst attention is paid to the innovatory nature of the work, particularly the use of inductive, deductive and integrated approaches to both change implementation and project supervision. ? The programme was monitored throughout using different data sources and the paper uses evaluative material retrospectively to provide answers to organizational and professional difficulties which arose during the course of the programme. ? The authors conclude that the use of combinations of different models for practice development has potential, but requires careful supervision. ? They also recommend that those involved in practice development are made fully aware of its local or micropolitics, and develop strategies to deal with change before it occurs, not after it has taken place.     

Mechanism of persistent infection associated with peritoneal implants.

The ability of rabbits to clear an intraperitoneal injection of Pseudomonas aeruginosa in the presence or absence of a surgically implanted peritoneal device was investigated. Sham-operated rabbits without an implant eliminated a P. aeruginosa challenge of 5 x 10(6) cfu/ml; lavage fluid and peritoneal tissues became culture-negative within 96 h. However, peritonitis developed in rabbits that were given the same number of bacteria in the presence of an implant; high bacterial counts were recovered from the lavage fluid and the device itself. Scanning and transmission electronmicroscopy revealed bacterial biofilms on the surface of the device. Insertion of pre-colonised devices demonstrated a rapid multiplication of sessile organisms within the resulting bacterial biofilm. Counts reached a plateau of about 1 x 10(7) cfu/cm2 of Silastic by day 16 and fluctuated around this level until the end of the study. Pre-immunisation with formalin-killed whole cells of P. aeruginosa did not reduce this bacterial growth despite high levels of specific IgG. The results confirm the failure of peritoneal defences to clear an infection in the presence of an implant following either challenge with planktonic bacteria or insertion of a pre-colonised device, and demonstrate the rapid development of bacterial biofilms on the surface of the implant which appear to protect the bacteria from host defences, even when primed by pre-immunisation.