Long-term results of total hip replacement in young patients who had ankylosing spondylitis. Eighteen to thirty-year results with survivorship analysis

We determined the long-term results of total hip replacement in a series of young patients who had ankylosing spondylitis. Between 1966 and 1978, forty-three Charnley low-friction arthroplasties were performed in twenty-four patients who had an average age of 28.8 years (range, nineteen to thirty-nine years) at the time of the operation. There were seventeen men and seven women. The average duration of follow-up for the series was 22.7 years (range, one month [a perioperative death] to 30.3 years). Four patients (seven hips) had died an average of 12.6 years (range, one month to 18.7 years) after the operation. The twenty surviving patients had clinical and radiographic follow-up until the time of writing or until both of the original components had been revised. All patients had substantial relief of pain and improvement of function and the range of motion of the joint. Twenty-one patients (88 per cent; thirty-nine hips) were completely free of pain (6 points, according to the scale of Merle d'Aubigne and Postel), and the remainder had only slight discomfort (5 points). Ten acetabular components and one femoral component were revised because of aseptic loosening, and one patient had a revision of both components because of late deep infection. Three additional femoral components were revised during a revision operation for a loose acetabular component. Although the femoral components were not loose, they had been in place for more than ten years and it was thought likely that the bearing surface was damaged. The average time to revision was 13.3 years (range, 4.0 to 20.3 years). At an average of 22.7 years, thirty-eight (88 per cent) of the original femoral components and thirty-two (74 per cent) of the original acetabular components remained in situ. The average annual rate of acetabular wear was 0.12 millimeter for the entire series. Only six hips (14 per cent) had minor heterotopic ossification, and none of the hips had clinically important ossification (class III or IV according to the system of Brooker et al.). To our knowledge, the present report describes the largest series of total hip arthroplasties, with the longest duration of follow-up, in young patients who had ankylosing spondylitis. Survivorship analysis with use of the Kaplan-Meier method revealed that the probability of survival of the femoral component (with 95 per cent confidence intervals) was 91 per cent (83 to 99 per cent) at twenty years and 83 per cent (72 to 94 per cent) at thirty years. The probability of survival of the acetabular components was 73 per cent (61 to 84 per cent) at twenty years and 70 per cent (57 to 83 per cent) at thirty years. The probability that both components would survive was 91 per cent (82 to 100 per cent) at ten years, 73 per cent (61 to 84 per cent) at twenty years, and 70 per cent (57 to 83 per cent) at thirty years. The Charnley low-friction arthroplasty provided consistently good long-term results, with a low rate of complications and revisions, in this group of young patients.     

An ecology of text: using text retrieval to study alife on the net

I introduce a new alife model, an ecology based on a corpus of text, and apply it to the analysis of posts to USENET News. In this corporal ecology posts are organisms, the newsgroups of NetNews define an environment, and human posters situated in their wider context make up a scarce resource. I apply latent semantic indexing (LSI), a text retrieval method based on principal component analysis, to distill from the corpus those replicating units of text. LSI arrives at suitable replicators because it discovers word co-occurrences that segregate and recombine with appreciable frequency. I argue that natural selection is necessarily in operation because sufficient conditions for its occurrence are met: replication, mutagenicity, and trait/fitness covariance. I describe a set of experiments performed on a static corpus of over 10,000 posts. In these experiments I study average population fitness, a fundamental element of population ecology. My study of fitness arrives at the unhappy discovery that a flame-war, centered around an overly prolific poster, is the king of the jungle.     

The uracil permease of Schizosaccharomyces pombe: a representative of a family of 10 transmembrane helix transporter proteins of yeasts

The uracil permease gene of Schizosaccharomyces pombe was cloned and sequenced. The deduced protein sequence shares strong similarities with five open reading frames from Saccharomyces cerevisiae, namely the uracil permease encoded by the FUR4 gene, the allantoin permease encoded by DAL4, a putative uridine permease (YBL042C) and two unknown ORFs YOR071c and YLR237w. A topological model retaining ten transmembrane helices, based on predictions and on experimental data established for the uracil permease of S. cerevisiae by Galan and coworkers (1996), is discussed for the four closest proteins of this family of transporters. The sequence of the uracil permease gene of S. pombe has been deposited in the EMBL data bank under Accession Number X98696.     

Destabilization and denaturation of cellular protein by glutathione depletion

There is an increasing realization that every effort should be made to minimize the exposure to ionizing radiation of patients and members of the dental team. There are, however, few published guidelines to assist the general practitioner in deciding whether or not radiographs are needed. There is even less information concerning the taking of dental radiographs of children. Using the Delphi Technique this study set out to seek a consensus amongst Consultant Paediatric Dentists (n = 36) working in the UK as to when dental radiographs should and should not be taken of children cared for within general dental services. A two-stage questionnaire was used and a response of 94% and 76% was obtained in the first and second questionnaire respectively. A consensus view was reached regarding whether or not radiographs should be taken in a series of 17 specific clinical situations.     

A comparison of two methods of oestrous synchronisation of hair sheep in the tropics

In the last years, the occurrence of pesticides and other chemicals in groundwater has been confirmed. The herbicide atrazine is among the pesticides most frequently detected in groundwater. In groundwater samples from the United States atrazine concentrations reached levels up to 10 micrograms/1. In our lysimeter experiments with radioactive labelled terbuthylazine we measured 2.87-4.20% of the applied radioactivity after 1160 days in the leachate.     

The regulation of membrane 125I- and 86Rb+ permeability in a virally transformed cell line (NCL-SG3) derived from the human sweat gland epithelium

We have explored the factors that may regulate membrane permeability in a cell line (NCL-SG3) derived from the human sweat gland epithelium. Ionomycin increased the rate of 125I-efflux from preloaded cells and this action appeared to be due to an increase in intracellular free calcium ([Ca2+]i). The ionomycin-evoked increase in 125I- efflux was reduced in cells that were exposed either to barium or to valinomycin in the presence of a high concentration of external potassium. It thus appears that a fraction of the ionomycin-evoked increase in 125I- efflux is due to the activation of potassium channels and experiments using 86Rb+ also suggested that ionomycin increased the rate of potassium efflux, an effect which was totally abolished by barium. Blockade of Na(+)-K(+)-2Cl- cotransport and of Cl- -HCO3- exchange reduced the basal rate of 125I- efflux and the ionomycin-evoked increase in 125I-efflux from control cells and from cells depolarized by valinomycin. These transport systems thus contribute to anion efflux, although [Ca2+]i-dependent chloride channels also appear to be present. Acetylcholine increases [Ca2+]i in the secretory cells of human sweat glands, but this neurotransmitter did not increase [Ca2+]i in NCL-SG3 cells and so membrane permeability was not under cholinergic control. Adrenaline did not increase [Ca2+]i, but this hormone did evoke cyclic-3',5'-adenosine monophosphate (cyclic AMP) production. However, membrane permeability was not under adrenergic control, as the cells did not appear to express functional, cyclic AMP-dependent anion channels. This may be because they were not fully differentiated under the culture conditions. ATP consistently evoked a dose-dependent increase in anion efflux that appeared to be mediated by [Ca2+]i. The increase in [Ca2+]i was initiated by the release of calcium from a limited internal store and was subsequently sustained by calcium influx. UTP and ADP also increased [Ca2+]i, whereas adenosine, AMP and alpha,beta-methylene ATP were without effect. These data thus suggest that a subclass of type 2 purine receptor, which is functionally coupled to phosphoinositidase C, is present in these cells.