Structure and biological activity of glasses and ceramics.

Biomaterials for repairing and regenerating parts of the human body play a key role in contemporary medicine, and have an increasing impact in modern society. Given the importance of orthopaedic medicine (bone is the second most replaced organ after blood), bioactive glasses and ceramics represent a key reference to guide technological advances in this field. Their established role in current biomedical applications has already led many research groups worldwide to look into their structural properties, with a view to identifying the molecular basis of their biological activity. As the efforts directed towards this crucial and exciting direction continue to increase, it is now timely to review the situation, in order to guide future investigations on structure-bioactivity relationships. In this introductory article, the field is reviewed, to provide an appropriate context for the contributions to this Theme Issue.

The utility of assessing the gross appearances of FNA specimens.

OBJECTIVE: Ideally, fine needle aspiration (FNA) cytology should be performed with near-patient assessment of the adequacy of the specimen by a cytopathologist. However, this is often not feasible. A cruder alternative is for the FNA practitioner to examine the gross appearances of the specimen and to try to predict the its quality. This study set out to determine the value of this approach. METHODS: The study was conducted in tertiary public hospitals in New Zealand and the UK. FNA gross material grading was performed by a variety of pathologists on FNA samples taken using manual guidance and image guidance. The FNA gross material grade was compared with the findings on microscopic examination. RESULTS: Nine out of 123 FNA samples were assessed as Grade 1 (unlikely to contain diagnostic material). All were subsequently reported as having insufficient diagnostic tissue on microscopic examination. Forty-two of the FNA samples were assessed as Grade 2 (possibly contains diagnostic material) and 46 as Grade 3 (probably contains diagnostic material). None from either of these grades was reported as showing insufficient diagnostic material on microscopic examination. Twenty-six cases were reported as Grade 4 (material suggesting a specific diagnosis). None of these was reported as showing insufficient diagnostic material on microscopic examination. The most common Grade 4 provisional diagnosis was that of a colloid cyst or colloid nodule of the thyroid (seven cases). Only two cases had misleading Grade 4 provisional diagnoses. Both were thought to be pus on gross examination but showed necrotic carcinoma on microscopic examination. CONCLUSIONS: The gross appearances of FNA samples can usually predict the adequacy of the samples and sometimes predict the final microscopic diagnosis. However, near-patient microscopic assessment of FNA specimens is preferable if available.

The gross appearances of fine needle aspiration cytology samples.

AIMS: This study set out to photograph and describe the gross appearances of fine needle aspiration (FNA) cytology samples of commonly encountered lesions. METHODS: During a 2 year period, a cytopathologist photographed the gross appearances of near patient FNA samples, concentrating on commonly encountered lesions. RESULTS: The gross appearances are described, accompanied by photographic illustrations. CONCLUSIONS: This paper describes and illustrates the gross appearances of FNA cytology samples of some commonly encountered lesions.

Cardiac troponin I concentrations in people presenting with diabetic ketoacidosis.

BACKGROUND: Elevated troponin concentrations may be observed in a wide spectrum of medical disorders in people without evidence of overt ischaemic heart disease. The prospective relationship between serum cardiac troponin I (cTnI) and diabetic ketoacidosis (DKA) has not been examined in adults. METHODS: Forty patients (14 male and 26 female) with type 1 diabetes were recruited. cTnI, creatine kinase (CK), cystatin C and beta-hydroxybutyrate were measured on admission and at 24, 48 and 72 h post-admission. Daily electrocardiographs were also performed. RESULTS: Four out of forty subjects presenting with DKA had an increase in cTnI (median (SD) 0.06 (0.31) microg/L). One of the subjects had multiple possible reasons for the elevated cTnI concentration. However, the other three subjects had no obvious precipitating factors. This cohort underwent echocardiography and thallium-201 scintigraphy, which revealed no abnormalities. CONCLUSIONS: Minor troponin elevations appear to occur in a small number of subjects with type 1 diabetes presenting with DKA. The clinical relevance of this at this stage remains unknown and further large-scale studies are suggested.

A problem in rotation therapy with X-rays: dose distributions with an axis of symmetry.

We give the equations which need to be solved to extend the work of Brahme, Roos, and Lax to dose distributions which are not circularly symmetrical. These equations do not contain the linear absorption coefficient, mu, explicitly so they are valid in principle for any mu. The general solution of these equations has not been found, but the solution given by Brahme, Roos, and Lax is used to extend their work to simple dose distributions with an axis of symmetry. Some examples are given and discussed.

A problem in rotation therapy with X rays.

The radiation field required to produce a dose distribution in rotation therapy may, in a certain approximation, be calculated using an integral equation, that is, the solution of the equation predicts the intensities needed to produce the dose distribution. The nature of this approximation is discussed and is shown to be connected with a Radon-type problem for circles through the origin provided the beam can be continuously modified during the rotation. The lowest order approximation provides a vivid geometrical way of looking at treatment planning which may be useful in novel situations and which will persist, to some extent, in higher-order approximations. Questions of scattering, and of the extension of the problem to a full three dimensional treatment are discussed.

The role of percutaneous transhepatic cholangiography and grey-scale ultrasound in the investigation and treatment of bile duct obstruction.

A total of 123 patients undergoing fine needle percutaneous transhepatic cholangiography (PTC) in Newport between 1977 and 1981 are reviewed. PTC was well tolerated with a 9 per cent complication rate, a 5 per cent failure rate and no mortality. Of 111 patients in whom a diagnosis of biliary obstruction was subsequently confirmed, PTC showed the presence of obstruction in 94 per cent, its site in 92 per cent and the correct cause in 87 per cent. Eighteen jaundiced patients were spared laparotomy on the basis of the PTC findings. Grey-scale ultrasound scanning was performed in 99 of these patients. Of 93 with subsequently verified biliary obstruction, ultrasound confirmed the presence of obstruction in 66 per cent, its site in 33 per cent and its cause in 29 per cent. It is concluded that PTC is the more useful investigation in the management of biliary obstruction and that its use may avoid unnecessary surgery.

Quantitative proton tomography: preliminary experiments.

An attempt has been made to see whether energetic protons (158 MeV) could be used instead of X-rays in computerized axial tomography to detect density differences of the order of those at which commercial X-ray tomographs cease to be useful. A circularly symmetrical phantom consisting of Lucite and sugar solutions was used, and density differences of 0-5% were reconstructed with reasonable accuracy from data obtained with very simple equipment. Discontinuities in either density or chemical composition, or both, seem to cause artifacts in the reconstruction. These may be related to the West-Sherwood effect.