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Biomedical subjects

C Sykes

Publications and source records attributed to C Sykes.

8 recordsLinked to original sources
PubMed2005

Adhesive capsulitis: sonographic changes in the rotator cuff interval with arthroscopic correlation.

OBJECTIVE: To evaluate the sonographic findings of the rotator interval in patients with clinical evidence of adhesive capsulitis immediately prior to arthroscopy. DESIGN AND PATIENTS: We prospectively compared 30 patients with clinically diagnosed adhesive capsulitis (20 females, 10 males, mean age 50 years) with a control population of 10 normal volunteers and 100 patients with a clinical suspicion of rotator cuff tears. Grey-scale and colour Doppler sonography of the rotator interval were used. RESULTS: Twenty-six patients (87%) demonstrated hypoechoic echotexture and increased vascularity within the rotator interval, all of whom had had symptoms for less than 1 year. Three patients had hypoechoic echotexture but no increase in vascularity, and one patient had a normal sonographic appearance. All patients were shown to have fibrovascular inflammatory soft-tissue changes in the rotator interval at arthroscopy commensurate with adhesive capsulitis. None of the volunteers or the patients with a clinical diagnosis of rotator cuff tear showed such changes. CONCLUSIONS: Sonography can provide an early accurate diagnosis of adhesive capsulitis by assessing the rotator interval for hypoechoic vascular soft tissue.

Adult↗
PubMed2001

ActA and human zyxin harbour Arp2/3-independent actin-polymerization activity.

The actin cytoskeleton is a dynamic network that is composed of a variety of F-actin structures. To understand how these structures are produced, we tested the capacity of proteins to direct actin polymerization in a bead assay in vitro and in a mitochondrial-targeting assay in cells. We found that human zyxin and the related protein ActA of Listeria monocytogenes can generate new actin structures in a vasodilator-stimulated phosphoprotein-dependent (VASP) manner, but independently of the Arp2/3 complex. These results are consistent with the concept that there are multiple actin-polymerization machines in cells. With these simple tests it is possible to probe the specific function of proteins or identify novel molecules that act upon cellular actin polymerization.

Actin Cytoskeleton↗
PubMed2000

Growing an actin gel on spherical surfaces.

Inspired by the motility of the bacteria Listeria monocytogenes, we have experimentally studied the growth of an actin gel around spherical beads grafted with ActA, a protein known to be the promoter of bacteria movement. On ActA-grafted beads F-actin is formed in a spherical manner, whereas on the bacteria a "comet-like" tail of F-actin is produced. We show experimentally that the stationary thickness of the gel depends on the radius of the beads. Moreover, the actin gel is not formed if the ActA surface density is too low. To interpret our results, we propose a theoretical model to explain how the mechanical stress (due to spherical geometry) limits the growth of the actin gel. Our model also takes into account treadmilling of actin. We deduce from our work that the force exerted by the actin gel on the bacteria is of the order of 10 pN. Finally, we estimate from our theoretical model possible conditions for developing actin comet tails.

Actins↗
PubMed1996

The characteristics and intervention histories of incarcerated and conduct-disordered youth.

OBJECTIVES: 1) To determine if incarcerated youth and conduct-disordered youth in treatment display similar risk factors associated with chronicity of antisocial behaviour; 2) to determine if incarcerated youth had experienced high numbers of interventions by many different agencies as has been reported for conduct-disordered youth in treatment. METHOD: The files of 25 conduct-disordered youth in treatment and 25 incarcerated youth were examined to extract all relevant data. RESULTS: Incarcerated youth were similar to conduct-disordered youth with regard to the number of symptoms of disruptive behaviour disorders, age of onset of behavioural problems, and family backgrounds. Both groups had high numbers of interventions and agencies in their histories. Interventions began earlier for the conduct-disordered youth. CONCLUSION: The distinction between conduct-disordered youth who are treated and youth who are incarcerated may be arbitrary and accidental. Given the similarity in the clinical characteristics, incarcerated youth should be offered help that is similar to that offered to conduct-disordered youth. Such help may lower the rate of recidivism.

Adolescent↗
PubMed1994

Continuity of care for conduct disordered youth.

The objectives of this study were to determine which risk factors associated with chronicity had been displayed by youths who had been treated for conduct disorder in a tertiary level mental health centre and also to count the number of interventions and the number of agencies involved during their many years in treatment. The files of 25 youths with conduct disorder were examined to extract all relevant data. The youths averaged nine years between first intervention and last discharge. Common risk factors were the early onset and the variety of antisocial behaviours and the multiple settings in which behaviours occurred. The youths experienced an average of 19 interventions by 15 agencies. Interventions lasted on average seven months with little occurrence of follow-up. The severity of antisocial behaviours increased from first to last intervention. The apparent ineffectiveness of treatment may be related to the short duration of treatments and the lack of follow-up which resulted in the involvement of many agencies.

Adolescent↗
PubMed1990

Immunoglobulin isotype production by cycling human B lymphocytes in response to recombinant cytokines and anti-IgM.

Actively cycling populations of purified human tonsilar B lymphocytes were examined for their capacity to secrete IgM, IgA, IgE and IgG of all four subclasses in direct response to recombinant cytokines; in some experiments, monoclonal antibody to IgM (anti-mu) was included in order to explore the influence of antigen receptor ligation on immunoglobulin (Ig) production. Enhanced IgM release was seen on culture of the cycling cells with either interleukin-2 (IL-2), IL-4 or interferon-alpha (IFN-alpha). IL-2 and IFN-alpha also augmented IgA production, whereas IL-4 had no effect on this isotype. IL-4 did, however, encourage the production of the IgG subclasses IgG1, IgG2 and IgG3, while IL-2 augmented IgG1 and IgG3 release and IFN-alpha increased IgG1 levels. IgG4 production, and that of IgE, failed to be perturbed by any of the cytokines assayed. Neither IL-1 alpha, IL-1 beta, IL-5 nor IFN-gamma significantly altered the profile of Ig isotype release. When confronted with anti-mu, cycling B cells demonstrated a marked suppression in IgM production. Suppression could not be overcome by the addition to culture of the normally IgM-promoting IL-4. Concomitant with the reduction in IgM levels, an increase in IgG release was observed. This was comprised of elevations in IgG1 and IgG3. Although not influencing IgA release directly, anti-mu was found to promote increased IgA production in co-culture with either IL-2 or IFN-alpha. The findings are discussed in the context of recent findings on Ig isotype control in both human and murine systems.

Antibodies, Anti-Idiotypic↗
PubMed1984

Chronic administration of the GABA-transaminase inhibitor ethanolamine O-sulphate leads to up-regulation of GABA binding sites.

In rats receiving the gamma-aminobutyric acid (GABA)-transaminase inhibitor ethanolamine O-sulphate (EOS) in their drinking water for up to 28 days, the number of GABAA and GABAB binding sites was increased compared to controls. There was no change in binding affinity at GABAA or GABAB sites. One week after EOS withdrawal, the number of GABAA and GABAAB sites in previously treated EOS rats did not differ from controls. There was no difference in the number or affinity of benzodiazepine binding sites between EOS-treated and control rats during EOS administration or withdrawal. There was no difference in the stimulation of benzodiazepine binding by GABA (alone or in the presence of NaCl) during EOS administration. Cortical and cerebellar GABA concentration was increased 3.2- to 4.6-fold and cortical glutamate decarboxylase (GAD) activity reduced 30-42%. The current required to induce electroshock convulsions did not differ between EOS-treated rats and control rats during EOS administration. We speculate that the stimulus for the increased number of GABAA and GABAB binding sites is a reduction in GABA release subsequent to a reduction in GAD activity.

4-Aminobutyrate Transaminase↗