Strontium-85 Scanning of Suspected Bone Disease

Strontium-85 scanning of suspected bone lesions in 81 patients has added to the criteria for the diagnosis of malignant and other lesions of bone. Of 46 patients with a previous history of malignant disease and skeletal symptoms negative radiological findings were recorded in 19, but nine of these had positive scans, eight of which when followed up over periods of up to four years proved to be metastatic. A similar prevalence of positive scans occurred in patients without a previous history of malignancy. Because of the anatomical localization of lesions made possible by this technique a tissue diagnosis was made in six patients, while fields of radiotherapy were altered in another seven. This technique can improve the management of patients with suspected bone disease.     

Modelling tree shape and structure in viral phylodynamics

Epidemiological models have highlighted the importance of population structure in the transmission dynamics of infectious diseases. Using HIV-1 as an example of a model evolutionary system, we consider how population structure affects the shape and the structure of a viral phylogeny in the absence of strong selection at the population level. For structured populations, the number of lineages as a function of time is insufficient to describe the shape of the phylogeny. We develop deterministic approximations for the dynamics of tips of the phylogeny over evolutionary time, the number of ‘cherries’, tips that share a direct common ancestor, and Sackin''s index, a commonly used measure of phylogenetic imbalance or asymmetry. We employ cherries both as a measure of asymmetry of the tree as well as a measure of the association between sequences from different groups. We consider heterogeneity in infectiousness associated with different stages of HIV infection, and in contact rates between groups of individuals. In the absence of selection, we find that population structure may have relatively little impact on the overall asymmetry of a tree, especially when only a small fraction of infected individuals is sampled, but may have marked effects on how sequences from different subpopulations cluster and co-cluster.     

The use of a hidden metal-capture reagent for the measurement of Na+−K+-ATPase activity: A new concept in cytochemistry

Summary The original lead-trapping method for demonstrating Na⁺–K⁺-ATPase activity was discredited because of the effect that lead ions can have on the substrate and on the enzyme. Current methods, that measure this activity by the related K⁺-dependent phosphatase activity, do not appear to measure activity that is known, from microchemistry, to occur in proximal convoluted tubules. The disadvantages of using lead appear to have been overcome by the use of a new reagent in which the lead is complexed with ammonium citrate ions; phosphate, liberated enzymatically, successfully competes with these ions. The activities of total ATPase and of the ouabain sensitive Na⁺–K⁺-ATPase have been measured in three regions of the nephron in the guinea-pig and in the rat. The relative activities found, by this method, in the different regions of the latter, appear to be comparable with results found by others, using microchemical methods applied to isolated regions of the nephron.     

Measuring Asymmetry in Time-Stamped Phylogenies

Previous work has shown that asymmetry in viral phylogenies may be indicative of heterogeneity in transmission, for example due to acute HIV infection or the presence of ‘core groups’ with higher contact rates. Hence, evidence of asymmetry may provide clues to underlying population structure, even when direct information on, for example, stage of infection or contact rates, are missing. However, current tests of phylogenetic asymmetry (a) suffer from false positives when the tips of the phylogeny are sampled at different times and (b) only test for global asymmetry, and hence suffer from false negatives when asymmetry is localised to part of a phylogeny. We present a simple permutation-based approach for testing for asymmetry in a phylogeny, where we compare the observed phylogeny with random phylogenies with the same sampling and coalescence times, to reduce the false positive rate. We also demonstrate how profiles of measures of asymmetry calculated over a range of evolutionary times in the phylogeny can be used to identify local asymmetry. In combination with different metrics of asymmetry, this combined approach offers detailed insights of how phylogenies reconstructed from real viral datasets may deviate from the simplistic assumptions of commonly used coalescent and birth-death process models.     

Genetic characterization of an Escherichia coli mutant deficient in organophosphonate biodegradation

An E. coli mutant deficient in organophosphonate biodegradation has been complemented with a cosmid library prepared from a BamHI partial digest of wild-type E. coli W3110. Mutant E. coli SL724, when transformed with cosmid pSL163 and plasmid pSL263, regained the ability to exploit ethylphosphonate as a sole source of phosphorus during growth. In route to complementation, the Tn5 insert of SL724 was subcloned and restriction enzyme mapped. Complementing pSL163 and pSL263 were also characterized via restriction enzyme digests.     

Randomised controlled trial for evaluation of fitness programme for patients with chronic low back pain.

OBJECTIVE--To evaluate a progressive fitness programme for patients with chronic low back pain. DESIGN--Single blind randomised controlled trial. Assessments were carried out before and after treatment by an observer blinded to the study and included a battery of validated measures. All patients were followed up by postal questionnaire six months after treatment. SETTING--Physiotherapy department of orthopaedic hospital. SUBJECTS--81 patients with chronic low back pain referred from orthopaedic consultants for physiotherapy. The patients were randomly allocated to a fitness programme or control group. INTERVENTION--Both groups were taught specific exercises to carry out at home and referred to a back-school for education in back care. Patients allocated to the fitness class attended eight exercise classes over four weeks in addition to the home programme and backschool. RESULTS--Significant differences between the groups were shown in the changes before and after treatment in scores on the Oswestry low back pain disability index (P < 0.005), pain reports (sensory P < 0.05 and affective P < 0.005), self efficacy reports (P < 0.05), and walking distance (P < 0.005). No significant differences between the groups were found by the general health questionnaire or questionnaire on pain locus of control. A benefit of about 6 percentage points on the disability index was maintained by patients in the fitness group at six months. CONCLUSION--There is a role for supervised fitness programmes in the management of moderately disabled patients with chronic low back pain. Further clinical trials, however, need to be established in other centres to confirm these findings.