29 research outputs found

    The clockfront and wavefront model revisited

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    The currently accepted interpretation of the clock and wavefront model of somitogenesis is that a posteriorly moving molecular gradient sequentially slows the rate of clock oscillations, resulting in a spatial readout of temporal oscillations. However, while molecular components of the clocks and wavefronts have now been identified in the pre-somitic mesoderm (PSM), there is not yet conclusive evidence demonstrating that the observed molecular wavefronts act to slow clock oscillations. Here we present an alternative formulation of the clock and wavefront model in which oscillator coupling, already known to play a key role in oscillator synchronisation, plays a fundamentally important role in the slowing of oscillations along the anterior–posterior (AP) axis. Our model has three parameters which can be determined, in any given species, by the measurement of three quantities: the clock period in the posterior PSM, somite length and the length of the PSM. A travelling wavefront, which slows oscillations along the AP axis, is an emergent feature of the model. Using the model we predict: (a) the distance between moving stripes of gene expression; (b) the number of moving stripes of gene expression and (c) the oscillator period profile along the AP axis. Predictions regarding the stripe data are verified using existing zebrafish data. We simulate a range of experimental perturbations and demonstrate how the model can be used to unambiguously define a reference frame along the AP axis. Comparing data from zebrafish, chick, mouse and snake, we demonstrate that: (a) variation in patterning profiles is accounted for by a single nondimensional parameter; the ratio of coupling strengths; and (b) the period profile along the AP axis is conserved across species. Thus the model is consistent with the idea that, although the genes involved in pattern propagation in the PSM vary, there is a conserved patterning mechanism across species

    The Community In-Reach and Care Transition (CIRACT) clinical and cost-effectiveness study: study protocol for a randomised controlled trial

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    Background Older people represent a significant proportion of patients admitted to hospital. Their care compared to younger patients is more challenging, length of stay is longer, risk of hospital-acquired problems higher and the risk of being re-admitted within 28 days greater. This study aims to compare a Community In-Reach and Care Transition (CIRACT) service with Traditional Hospital Based rehabilitation (THB-Rehab) provided to the older person. The CIRACT service differs from the THB-rehab service in that they are able to provide more intensive hospital rehabilitation, visiting patients daily, and are able to continue with the patient’s rehabilitation following discharge allowing a seamless, integrated discharge working alongside community providers. A pilot comparing the two services showed that the CIRACT service demonstrated reduced length of stay and reduced re-admission rates when analysed over a four-month period. Methods/Design This trial will evaluate the clinical and cost-effectiveness of the CIRACT service, conducted as a randomised controlled trial (RCT) with an integral qualitative mechanism and action study designed to provide the explanatory and theoretical components on how the CIRACT service compares to current practice. The RCT element consists of 240 patients over 70 years of age, being randomised to either the THB therapy group or the CIRACT service following an unplanned hospital admission. The primary outcome will be hospital length of stay from admission to discharge from the general medical elderly care ward. Additional outcome measures including the Barthel Index, Charlson Co-morbidity Scale, EuroQoL-5D and the modified Client Service Receipt Inventory will be assessed at the time of recruitment and repeated at 91 days post-discharge. The qualitative mechanism and action study will involve a systematic programme of organisational profiling, observations of work processes, interviews with key informants and care providers and tracking of participants. In addition, a within-trial economic evaluation will be undertaken comparing the CIRACT and THB-rehab services to determine cost-effectiveness. Discussion The outcome of the study will inform clinical decision-making, with respect to allocation of resources linked to hospital discharge planning and re-admissions, in a resource intensive and growing group of patients

    Clinical outcomes and response to treatment of patients receiving topical treatments for pyoderma gangrenosum: a prospective cohort study

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    Background: pyoderma gangrenosum (PG) is an uncommon dermatosis with a limited evidence base for treatment. Objective: to estimate the effectiveness of topical therapies in the treatment of PG. Methods: prospective cohort study of UK secondary care patients with a clinical diagnosis of PG suitable for topical treatment (recruited July 2009 to June 2012). Participants received topical therapy following normal clinical practice (mainly Class I-III topical corticosteroids, tacrolimus 0.03% or 0.1%). Primary outcome: speed of healing at 6 weeks. Secondary outcomes: proportion healed by 6 months; time to healing; global assessment; inflammation; pain; quality-of-life; treatment failure and recurrence. Results: Sixty-six patients (22 to 85 years) were enrolled. Clobetasol propionate 0.05% was the most commonly prescribed therapy. Overall, 28/66 (43.8%) of ulcers healed by 6 months. Median time-to-healing was 145 days (95% CI: 96 days, ∞). Initial ulcer size was a significant predictor of time-to-healing (hazard ratio 0.94 (0.88;80 1.00); p = 0.043). Four patients (15%) had a recurrence. Limitations: No randomised comparator Conclusion: Topical therapy is potentially an effective first-line treatment for PG that avoids possible side effects associated with systemic therapy. It remains unclear whether more severe disease will respond adequately to topical therapy alone

    Autoantibodies and Sjogren's Syndrome in multiple sclerosis, a reappraisal.

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    Rheumatologic diseases may cause neurologic disorders that mimic multiple sclerosis (MS). A panel of serum autoantibodies is often obtained as part of the evaluation of patients suspected of having MS.To determine, in light of recently revised diagnostic criteria for MS, neuromyelitis optica, and Sjogren's Syndrome, if testing for autoantibodies in patients with a confirmed diagnosis of MS would reveal a frequency or demonstrate a clinical utility divergent from previous reports or lead to identification of undiagnosed cases of Sjogren's Syndrome.Convenience sample cross-sectional study of MS patients recruited from the OHSU Multiple Sclerosis Center.Autoantibodies were detected in 38% (35/91) of patients with MS and were not significantly associated with disease characteristics or severity. While four patients had SSA antibodies, none met diagnostic criteria for Sjogren's Syndrome.Rheumatologic autoantibodies are frequently found in MS patients and are not associated with disease severity or systemic rheumatologic disease. Our demonstration of the low specificity of these autoantibodies suggests that the diagnostic utility and cost-effectiveness of testing is not supported when there is strong clinical suspicion of MS and low clinical suspicion of rheumatologic disease
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