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M Clarke

Publications and source records attributed to M Clarke.

At least 55 records · Page 3Linked to original sources
PubMed2001

Patient care.

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Dental Care↗
PubMed2001

Discovery of radio emission from the brown dwarf LP944-20.

Brown dwarfs are not massive enough to sustain thermonuclear fusion of hydrogen at their centres, but are distinguished from gas-giant planets by their ability to burn deuterium. Brown dwarfs older than approximately 10 Myr are expected to possess short-lived magnetic fields and to emit radio and X-rays only very weakly from their coronae. An X-ray flare was recently detected on the brown dwarf LP944-20, whereas previous searches for optical activity (and one X-ray search) yielded negative results. Here we report the discovery of quiescent and flaring radio emission from LP944-20, with luminosities several orders of magnitude larger than predicted by the empirical relation between the X-ray and radio luminosities that has been found for many types of stars. Interpreting the radio data within the context of synchrotron emission, we show that LP944-20 has an unusually weak magnetic field in comparison to active M-dwarf stars, which might explain the previous null optical and X-ray results, as well as the strength of the radio emissions compared to those at X-ray wavelengths.

Journal Article↗
PubMed2001

Just say 'no'.

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Decision Making↗
PubMed2001

Systemic therapy for treating locoregional recurrence in women with breast cancer.

BACKGROUND: Between 10% and 35% of women with operable breast cancer will experience an isolated locoregional recurrence following their primary treatment. There is currently no good evidence that adjuvant systemic treatment is effective in this situation and there is no standard treatment for women who have such a recurrence. OBJECTIVES: To investigate whether additional systemic treatment will improve the result of local therapy in regard to relapse-free and overall survival in women with potentially curatively resected loco-regional recurrence following breast cancer, who have not had a previous or synchronous distant metastases. SEARCH STRATEGY: Searches were done, in the first half of 2001, of the specialised register of the Cochrane Breast Cancer Collaborative Review Group, The Cochrane Library, MEDLINE and EMBASE. In addition, the records of the Early Breast Cancer Trialists' Collaborative Group were checked for any relevant trials. The citations in articles reviewing the treatment of locoregional recurrence of breast cancer were checked. SELECTION CRITERIA: Randomised controlled trials or trials in which women were allocated to treatment or observation by a quasi-random process (such as alternation or date of birth) were eligible. Our aim was to consider separately women with a first incidence of isolated loco-regional recurrence in the treated breast, the chest wall or the regional lymphnode areas (except clavicular nodes) which can be resected without (R0) or with (R1) microscopically demonstrable residual disease. Women with previous or synchronous distant metastases were to be excluded from this part of the review. The second part of the review was to consider women with inoperable loco-regional recurrence and / or clavicular lymphnode involvement, regardless of previous or synchronous metastases. DATA COLLECTION AND ANALYSIS: We identified three closed studies in which there were a total of four randomised comparisons of systemic therapy versus observation for women who have received radiotherapy for loco-regional recurrence of breast cancer. One trial assessed Actinomyicin-D and randomised 32 patients in the 1960s and another randomised the same number of women to alpha-interferon versus observation in the early 1980s. The Swiss SAKK trial assessed tamoxifen for "good risk" patients and combination chemotherapy (Vincristine, Doxorubicin and Cyclophosphamide) for "poor risk" patients. It randomised 178 and 50 women respectively during 1982-1991. Where possible, data on relapse-free and overall survival were extracted for these trials and analysed using RevMan 4.1. No attempt was made to pool the results of the studies because of clinical heterogeneity and the small number of randomised patients. Three ongoing trials of chemotherapy versus observation have been identified. MAIN RESULTS: The trial of 32 women who received either radiotherapy alone or in combination with systemic administration of Actinomycin-D found that chemotherapy improved the local control rate but had no apparent effect on overall survival. The interferon trial, which also included a total of only 32 patients, showed that the addition of alpha-Interferon to local treatment of locoregional recurrent breast cancer had no apparent effect on the further course of the disease. The Swiss SAKK trial of tamoxifen (178 women randomized) found an improvement in disease-free survival but not in overall survival and no results are available for the 50 women randomized into the concurrent trial of chemotherapy. The three ongoing trials of chemotherapy have a total target accrual of nearly 2000 patients. REVIEWER'S CONCLUSIONS: This systematic review of randomised trials provides insufficient evidence to do other than conclude that the most appropriate form of practice for women with loco-regional recurrence of breast cancer is participation in randomised trials of systemic treatment versus observation.

Antineoplastic Agents↗
PubMed2001

Molecular organization of a recombinant subviral particle from tick-borne encephalitis virus.

The tick-borne encephalitis (TBE) flavivirus contains two transmembrane proteins, E and M. Coexpression of E and the M precursor (prM) leads to secretion of recombinant subviral particles (RSPs). In the most common form of these RSPs, analyzed at a 19 A resolution by cryo-electron microscopy (cryo-EM), 60 copies of E pack as dimers in a T = 1 icosahedral surface lattice (outer diameter, 315 A). Fitting the high-resolution structure of a soluble E fragment into the RSP density defines interaction sites between E dimers, positions M relative to E, and allows assignment of transmembrane regions of E and M. Lateral interactions among the glycoproteins stabilize this capsidless particle; similar interactions probably contribute to assembly of virions. The structure suggests a picture for trimer association under fusion-inducing conditions.

Cryoelectron Microscopy↗
PubMed2001

Pharmacological differences between the human and rat vanilloid receptor 1 (VR1).

Vanilloid receptors (VR1) were cloned from human and rat dorsal root ganglion libraries and expressed in Xenopus oocytes or Chinese Hamster Ovary (CHO) cells. Both rat and human VR1 formed ligand gated channels that were activated by capsaicin with similar EC(50) values. Capsaicin had a lower potency on both channels, when measured electrophysiologically in oocytes compared to CHO cells (oocytes: rat=1.90+/-0.20 microM; human=1.90+/-0.30 microM: CHO cells: rat=0.20+/-0.06 microM; human=0.19+/-0.08 microM). In CHO cell lines co-expressing either rat or human VR1 and the calcium sensitive, luminescent protein, aequorin, the EC(50) values for capsaicin-induced responses were similar in both cell lines (rat=0.35+/-0.06 microM, human=0.53+/-0.03 microM). The threshold for activation by acidic solutions was lower for human VR1 channels than that for rat VR1 (EC(50) pH 5.49+/-0.04 and pH 5.78+/-0.09, respectively). The threshold for heat activation was identical (42 degrees C) for rat and human VR1. PPAHV was an agonist at rat VR1 (EC(50) between 3 and 10 microM) but was virtually inactive at the human VR1 (EC(50)>10 microM). Capsazepine and ruthenium red were both more potent at blocking the capsaicin response of human VR1 than rat VR1. Capsazepine blocked the human but not the rat VR1 response to low pH. Capsazepine was also more effective at inhibiting the noxious heat response of human than of rat VR1.

Amino Acid Sequence↗
PubMed2001

Double dose-intensive chemotherapy with autologous stem cell support for relapsed and refractory testicular cancer: the University of Michigan experience and literature review.

Testicular cancer patients refractory or in relapse after primary chemotherapy have < or =25% 5-year progression-free survival with salvage. To improve prognosis, patients entered a phase I/II tandem dose-escalation trial of carboplatin (1500-2100 mg/m(2)) and etoposide (1200-2250 mg/m(2)) with ABMT. Patients were eligible for a second cycle if disease progression was absent and performance status allowed. From August 1990 to June 1998, 29 males (25 NSGCT) were treated. At the time of ABMT, 10 were chemosensitive, four were chemoresistant, and 10 were absolutely refractory to platinum. Disease status (no. patients) at transplant: primary refractory disease (six), first relapse (10), second relapse (eight), third relapse (five). Fifteen (52%) received both transplants. Treatment-related mortality was 10%. Best response after ABMT included: two CR, one CR surgically NED, five PR, three PR surgically NED, seven SD, and eight PD. Eight (28%) patients are continuously progression-free a median 60 months (range, 31-93) from first ABMT. Three seminoma patients remain progression-free. Of five long-term NSGCT survivors, four were treated in first relapse with platinum-sensitive disease. Eighteen relapses occurred a median of 4 months after ABMT I (two late relapses at 28 and 44 months). The median PFS and OS for the whole group are 4 and 14 months, respectively. Patients with relapsed/ refractory testicular cancer benefit most from ABMT if they have platinum-sensitive disease in first relapse. Patients who do poorly despite ABMT have a mediastinal primary site, true cisplatin-refractory disease, disease progression prior to ABMT, and/or markedly elevated betaHCG at ABMT. New treatment modalities are needed for the latter group.

Adolescent↗
PubMed2001

Patterns of onset of disability in activities of daily living with age.

OBJECTIVES: To investigate the order in which activities of daily living (ADLs) are lost and whether the order is invariant between the sexes and age groups. DESIGN: Longitudinal data from the first five rounds of a routine health assessment by a nurse in participant's own home. SETTING: One large UK general practice with a list size of 32,500. PARTICIPANTS: Patients registered with the practice and age 75 and older. MEASUREMENTS: Disability was measured by self-report of performance in seven ADLs: mobility around the home, getting to and from the toilet, transfer from chair, transfer from bed, feeding, dressing, and bathing. Disability in each ADL was classified as being independent but having difficulty, using aids or help, or being unable to perform. Age at onset of disability in each ADL was calculated and analyzed using Kaplan-Meier plots and Cox regression models. Subjects who had died or remained independent by their last assessment were not included. RESULTS: The mean times between health assessments was approximately 20 months but with substantial variability both within and between individuals. A total of 1,344 people reported no difficulty in any ADL initially and 47.6% (640) subsequently reported disability. The order of activity restriction was bathing, mobility, toileting, dressing, transfers from bed and chair, and feeding. Women had a higher risk of disability in bathing (relative risk (RR) = 1.6, 95% confidence interval (CI) 1.3-1.9, P < .001) and toileting (RR = 1.7, 95% CI 1.2-2.5, P = .003), while for all ADLs there was a significant increase in the risk of disability with increasing age. The order of onset of disability for ADLs was invariant across sex and age groups. CONCLUSION: Lower-extremity strength (bathing, mobility, toileting) appears to be lost in older people before upper-extremity strength (dressing, feeding). Further work is now needed to develop prevention strategies to delay the onset of these disabilities.

Activities of Daily Living↗
PubMed2001

Cognitive behavioural psychotherapy: a comparison between younger and older adults in two inner city mental health teams.

There is little evidence about the efficacy of Cognitive Behavioural Therapy (CBT) in the older adult population. Research highlights that the preferred treatment for this group appears to be medication. This study compares an older adult mental health service with a younger adult service in terms of range of referrals, outcomes, attendance rates and length of time in therapy. The range of disorders referred was a wide mix of anxiety disorders and depression. There were no significant differences in therapy outcomes apart from home adjustment measures where older adults showed greater improvement. Younger adults showed significantly higher rates of non- attendance (DNA) and had higher dropout rates. Possible reasons for this are discussed. CBT appeared effective in both age groups, however older adults were treated more quickly due to a higher attendance rate.

Adult↗
PubMed2001

Clinical features of a novel TIMP-3 mutation causing Sorsby's fundus dystrophy: implications for disease mechanism.

AIMS: To describe the phenotype in three family members affected by a novel mutation in the gene coding for the enzyme tissue inhibitor of metalloproteinase-3 (TIMP-3). METHODS: Three members of the same family were seen with a history of nyctalopia and visual loss due to maculopathy. Clinical features were consistent with Sorsby's fundus dystrophy. Exon 5 of the gene coding for TIMP-3 was amplified by the polymerase chain reaction, single strand conformation polymorphism analysis undertaken and exon 5 amplicons were directly sequenced. RESULTS: Onset of symptoms was in the third to fourth decade. Five of six eyes had geographic macular atrophy rather than neovascularisation as a cause for central visual loss. Peripheral retinal pigmentary disturbances were present. Scotopic ERGs were abnormal in all three. Mutation analysis showed a G-->T transversion in all three resulting in a premature termination codon, E139X, deleting most of the carboxy terminal domain of TIMP-3. CONCLUSIONS: The patients described had a form of Sorsby's fundus dystrophy which fell at the severe end of the spectrum of this disease. Postulated disease mechanisms include deposition of dimerised TIMP-3 protein.

Adult↗
PubMed2001

Case-control study of leatherwork and male infertility.

OBJECTIVES: To test the hypothesis that leatherwork is associated with male infertility mediated through the development of oligozoospermia. The basis of any association was postulated, at the outset, to be with exposure to the solvents used in leatherwork. METHODS: All new referrals with infertility presenting in Leicestershire hospital clinics between November 1988 and September 1992 and Kettering District General Hospital from August 1990 were eligible to participate; 88.5% agreed to be interviewed. Exposure to leatherwork and work with solvents was defined by job title. Comparisons were made with fertile controls and in an analysis within men from infertile couples with oligozoospermia as the primary outcome. Effects on sperm motility and deformity were investigated secondarily. Analyses used logistic regression for binary outcomes and multilevel modelling for continuous outcomes. RESULTS: 1906 men were interviewed. Compared with the fertile controls the men from infertile couples were 1.10 times (95% confidence interval (95% CI) 0.46 to 2.63; p=0.99) more likely to be leatherworkers and 1.73 times (95% CI 1.26 to 2.38; p<0.001) more likely to work with solvents. Compared with other men, leatherworkers were 1.20 times (95% CI 0.43 to 3.33; p=0.73) more likely to present with oligozoospermia and 1.65 times (95% CI 0.37 to 7.30; p=0.51) more likely to present with teratozoospermia. Being a leatherworker was associated with only a 6% reduction in sperm concentration; motility and deformity were similarly unaffected by this exposure. Work with solvents did not statistically, nor clinically, increase the risk of oligozoospermia, teratozoospermia, or asthenozoospermia. CONCLUSIONS: There was little evidence to support the hypothesis that leatherwork is associated with an increased risk of presenting with infertility or oligozoospermia. There was limited evidence that leatherwork is a risk factor for teratozoospermia. Workers with solvents were at an increased risk of presenting with infertility, although this was not mediated through effects on standard measures of semen quality; this finding merits further investigation.

Adult↗
PubMed2001

DICE 2: a further investigation of the effects of chance in life, death and subgroup analyses.

In an investigation into how chance might influence the distribution of deaths in a randomised trial and the time of those deaths, and to highlight the possible dangers of subgroup analyses, 100 randomised controlled trials were simulated and 50 subgroup pairs were simulated for some of these trials. Each of 580 control patients from a colorectal cancer trial was randomly coded to simulate allocation to treatment or control, the main outcome measure being time to death. Not surprisingly, most of the 100 trials gave non-significant results. Four were conventionally significant with logrank 2p-values of less than 0.05. The most extreme result was associated with a logrank 2p-value of 0.003, showing an absolute reduction in four-year mortality of 40% (SD 15) for patients allocated to treatment. One of the simulated prognostic factors for this trial (subgroup 13) showed that mortality for one type of patient was non-significantly slightly increased by treatment, whereas treatment reduced four-year mortality by 64% (SD 16) among the other patients in the trial (2p = 0.00006). Similar, extreme results were found for a trial of borderline statistical significance overall. Chance can influence the overall results of any randomised controlled trial, regardless of how well it is conducted, and can play an even more powerful role in the results of subgroup analyses. This should be borne in mind both by trialists when reporting their results and by readers and reviewers of those reports.

Bias↗