The friction of explanted hip prostheses

Charnley prostheses, retrieved at revision surgery, were studied to assess the effects of friction on the total hip replacement procedure. Frictional resistance was measured using the Durham hip function simulator under both dry and lubricated conditions. The friction factor values (f) for the explanted prostheses were found to have a non- Gaussian distribution with medians of 0.13 [inter-quartile range (IQR) 0.10-0.16] and 0.06 (IQR 0.005-0.08) for dry and lubricated (n = 0.01 Pa s) regimes, respectively. New Charnley prostheses had values of f equal to 0.11 +/- 0.025 and 0.04 +/- 0.01 under the same conditions, and showed no large deviation from a Gaussian distribution. There was found to be a statistically significant difference in the medians of the friction factors for new and retrieved prostheses in the lubricated regime. Ingression of cement into the worn region of the cup was found to increase the friction factor significantly under dry conditions. There was no evidence of an increase in the friction factor or torque for those joints that had a loose socket with respect to those that were fixed at revision. A decrease in the frictional torque against number of cycles undergone by the joint in vivo may indicate that a fatigue-type process may have a role in the loosening of the socket. However, this relationship was found not to be significant for friction measured under lubricated conditions and it seems unlikely that the frictional torque generated in this type of prosthesis will contribute significantly to the long-term loosening of the socket.      

Fractionated total-body irradiation and high-dose etoposide as a preparatory regimen for bone marrow transplantation for 94 patients with chronic myelogenous leukemia in chronic phase

Ninety-four consecutive patients with chronic myelogenous leukemia in first clinical chronic phase, median age of 34.0 years (range, 6.8 to 52.4 years), with a histocompatible sibling donor, were treated with fractionated total body irradiation (1,320 cGy) and high-dose etoposide (60 mg/kg) followed by allogeneic bone marrow transplantation (BMT). The median time from diagnosis to BMT was 7.0 months (range, 2.3 to 72.0 months). Sixty patients were treated before BMT with hydroxyurea alone, four patients with busulfan alone, one patient with interferon alone, and the other 29 patients were treated with various combinations of these drugs. Cumulative probabilities of overall survival, event- free survival, and relapse at 5 years were 73%, 64%, and 14%, respectively. The median follow-up time for surviving patients was 38 months, ranging from 12 to 88 months. By stepwise Cox regression analysis, significant prognostic variables were age at transplant, acute graft-versus-host disease > or = grade II, cytomegalovirus- associated interstitial pneumonitis, and years from diagnosis to BMT.     

Myocardial infarct size quantification by MR imaging early after coronary artery occlusion in dogs

The feasibility of using magnetic resonance (MR) imaging to estimate myocardial infarct size was explored in an in vitro model using only the inherent differences in contrast between infarcted and noninfarcted myocardium. Eight dogs underwent coronary occlusion; their hearts were removed 6 hours later. Estimates of T2 for normal and infarcted myocardium were derived from MR images. Infarct size was quantified anatomically using triphenyltetrazolium-chloride (TTC) staining and compared with MR estimates. The T2 values derived from the images clearly discriminated between infarcted (126 +/- 22 msec) and normal myocardium (88 +/- 10 msec, P less than .05), providing images with good contrast between normal and infarcted myocardium. Comparable differences in T2 values were also noted from spectrometric determinations. Estimates of infarct size by MR imaging compared well with TTC estimates (r = 0.98) over a wide range of infarct sizes from 3% to 29% of the left ventricular mass. These results suggest the potential for in vivo quantification of infarct size based on the inherent contrast difference between infarcted and normal myocardium.     

Essential skills for purchasing — The views of directors of public health andhealth authority chief executives

Since the NHS reforms, health authorities have been purchasing health care and have been advised that publichealth considerations must inform all NHS activities, and that the Director of Public Health must be supported by a team of qualified support staff. This survey of directors of public health and health authority chief executives in England shows the skills currently available to support health authority purchasing, and the perceived importance of this wide range of skills to the purchasing process. Future models of purchasing will need to ensure access by purchasers to public health and multi-disciplinary advice.     

A comparison of histological and immunohistochemical methods for quantifying the pathological lesions of Pick's disease

Counts of Pick bodies (PB), Pick cells (PC), senile plaques (SP) and neurofibrillary tangles (NFT) were made in the frontal and temporal cortex from patients with Pick's disease (PD). Lesions were stained histologically with hematoxylin and eosin (HE) and the Bielschowsky silver impregnation method and labeled immunohistochemically with antibodies raised to ubiquitin and tau. The greatest numbers of PB were revealed by immunohistochemistry. Counts of PB revealed by ubiquitin and tau were highly positively correlated which suggested that the two antibodies recognized virtually identical populations of PB. The greatest numbers of PC were revealed by HE followed by the anti-ubiquitin antibody. However, the correlation between counts was poor, suggesting that HE and ubiquitin revealed different populations of PC. The greatest numbers of SP and NFT were revealed by the Bielschowsky method indicating the presence of Alzheimer-type lesions not revealed by the immunohistochemistry. In addition, more NFT were revealed by the anti-ubiquitin compared with the anti-tau antibody. The data suggested that in PD: (i) the anti-ubiquitin and anti-tau antibodies were equally effective at labeling PB; (ii) both HE and anti-ubiquitin should be used to quantitate PC; and (iii) the Bielschowsky method should be used to quantitate SP and NFT.     

Quantitative liver function in patients with rheumatoid arthritis treated with low-dose methotrexate: a longitudinal study

The objectives were to determine quantitative liver function prospectively in patients with rheumatoid arthritis (RA) treated with low-dose methotrexate (MTX), to search for risk factors for a loss of quantitative liver function and to assess the relationship between quantitative liver function and histological staging. A total of 117 patients with RA (ACR criteria, 85 women, mean age 59 yr) had measurements of galactose elimination capacity (GEC), aminopyrine breath test (ABT) and liver enzymes [aspartate amino transferase (AST), alanine amino transferase (ALT), alkaline phosphatase (AP), 7-glutamyl transferase (GGT), bile acids, bilirubin, albumin] before treatment with weekly i.m. MTX injections and every year thereafter. In 16 patients, liver biopsies were performed. Before the introduction of MTX, mean GEC was 6.6 mg/min/kg [5th to 95th percentile (5-95 PC) 5.1- 8.5; reference range 6.0-9.1] and mean ABT was 0.80% kg/mmol (5-95 PC 0.42-1.30: reference range 0.6-1.0). During treatment with MTX [mean weekly dose 11.8 mg (5-95 PC 5.4-20.2), mean observation period 3.8 yr (5-95 PC 0.4-6.9)], significant declines of GEC (-0.12 mg/min/kg per year. t = 3.30, P < 0.002) and ABT (-0.06% kg/mmol per year, t = 4.81, P < 0.001) were observed. Negative correlations were found between the annual change in GEC and GEC at baseline (Rs = -0.40, P < 0.0001), and the annual change in ABT and ABT at baseline (Rs = -0.43, P < 0.0001). No correlations were found between the annual change in GEC or ABT and weekly MTX dose, age or percentage of increased liver enzymes, and no effect of a history of alcohol consumption > 30 g/week became evident. Two patients with Roenigk grade III had impaired quantitative liver function, while 14 patients with Roenigk grades I and II exhibited a high variability of GEC and ABT from normal to abnormal values. The continuous declines in GEC and ABT observed deserve attention in patients with prolonged treatment. Patients with a low GEC or ABT at baseline seem not to be at increased risk for a further loss of quantitative liver function. An impaired GEC or ABT does not necessarily concur with hepatic fibrosis on histological examination.