Search PubMed⌕ Search

Biomedical subjects

M Clarke

Publications and source records attributed to M Clarke.

At least 127 records · Page 7Linked to original sources
PubMed1998

Automatic adjustment of pacemaker stimulation output correlated with continuously monitored capture thresholds: a multicenter study. European Microny Study Group.

Pacing threshold is affected by many factors. A pacing system able to confirm capture at each beat and automatically adjust its output close to the actual pacing threshold is highly desirable. This study evaluates the safety and efficacy of the Autocapture function of the Pacesetter Microny SR+. One hundred thirteen patients were recruited from 16 centers in 7 European countries and followed up for 1 year. All pacemakers were implanted with Pacesetter's low polarization, bipolar leads. The key feature of Autocapture is the immediate delivery of a 4.5 V safety backup pulse 62.5 ms after any ineffective ongoing low output pulse. Holter recordings confirmed total reliability of this feature without any exit block. The measured evoked response (ER) signal was stable over time. Acute and chronic pacing thresholds measured by VARIO and Autocapture tests correlated (r > 0.79) over the period of the study. The incidence of backup pulses was 1.1% during pacing. With Autocapture programmed ON, the overall total current consumption was 4.1 microA for VVI and 5.0 microA for VVIR pacing. This study proved that the Autocapture safely and reliably regulates the pacemaker's output according to the prevailing threshold thus providing maximum patient safety and prolonging service life.

Aged↗
PubMed1998

Oral health status of Canadian-born and immigrant adolescents in North York, Ontario.

Studies from a number of countries, including Canada, have demonstrated that the oral health status of immigrants is worse than that of their native-born counterparts and that they make less use of dental services. To date, however, little information is available which documents changes in immigrant oral health following immigration. This paper reports the results of a study conducted in the City of North York, Ontario, that examined the oral health status of Canadian-born and immigrant adolescents aged 13 and 14 years. The former had better oral health than the latter on all parameters assessed and made more use of dental services. Within the immigrant population, there was a significant association between oral health and time since immigration. Those who had been in Canada 6 or more years were significantly healthier than those who had arrived within the preceding 2 years. While changing patterns of immigration may account for part of these differences, the data suggest that access to dental public health programs, delivered to students between the ages of 4 and 14 years, have been effective in improving the oral health of those born outside Canada. Since these programs cease at age 13 or 14 years, barriers to accessing the private dental care sector may mean that the residual inequities and inequalities evident in the data widen as these individuals age.

Adolescent↗
PubMed1998

Rapid identification of Candida dubliniensis by indirect immunofluorescence based on differential localization of antigens on C. dubliniensis blastospores and Candida albicans germ tubes.

There is a clear need for the development of a rapid and reliable test for the identification of Candida dubliniensis and for the discrimination of this species from Candida albicans. In the present study we have investigated the potential use of C. dubliniensis-specific antigens as a basis for its identification. We produced an anti-C. dubliniensis serum which, after adsorption with C. albicans blastospores, was found to differentially label C. dubliniensis isolates in an indirect immunofluorescence test. In this test, the antiserum reacted with blastospores and germ tubes of C. dubliniensis and with blastospores of Candida krusei and Rhodotorula rubra but did not react with blastospores of several other Candida species including C. albicans. The antiserum also reacted with C. albicans germ tubes. The anti-C. dubliniensis adsorbed serum reacted with specific components of 25, 28, 37, 40, 52, and 62 kDa in the C. dubliniensis extract and with a variety of antigens from other yeast species. The antigens from non-C. dubliniensis yeasts showing reactivity with the anti-C. dubliniensis adsorbed serum are mostly expressed within the cell walls of these yeast species, and this reactivity does not interfere with the use of the anti-C. dubliniensis adsorbed serum in an indirect immunofluorescence test for the rapid identification of C. dubliniensis.

AIDS-Related Opportunistic Infections↗
PubMed1998

Frontal and occipital horn ratio: A linear estimate of ventricular size for multiple imaging modalities in pediatric hydrocephalus.

OBJECTIVE: Measurement of ventricular size is important in pediatric patients with hydrocephalus, especially those who are being followed with cerebrospinal fluid (CSF) shunts. While volumetric techniques are a more accurate estimate of true ventricular volume, they are often impracticable when multiple modalities including ultrasound are used. Volumetric area and linear measurements were compared to find the most reasonable measurement method. METHODS: Sixty-four computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) scans from 25 children aged 0-17 years with hydrocephalus, before and after treatment, were measured. Measurements included ventricular volume, a ventricular/brain ratio, and four standard linear measures (Evans' ratio, Huckman's measurement, minimal lateral ventricular width, and lateral ventricular span at the body). We also included a new ratio, which accounts for often disproportionate occipital horn expansion in pediatric patients, called the frontal and occipital horn ratio. Volume and linear measurements were compared using the Spearman's correlation coefficients and correlations were further differentiated using a Z test statistic. The frontal and occipital horn ratio was also measured on CT, MRI, and US scans from 44 normal children aged 0-17 years to identify normal values. The effect of age was determined by linear regression. RESULTS: The best linear correlation with ventricular size was the frontal + occipital horn ratio (r = 0.852) and was equivalent to the ventricular/brain ratio (r = 0.891), previously shown to have the highest correlation with ventricular volume. Evans' ratio correlates less well (r = 0.423). The normal frontal and occipital horn ratio is 0.37 and is independent of age. CONCLUSIONS: The frontal and occipital horn ratio is a simple method of evaluating ventricular size in pediatric hydrocephalus patients with CSF shunts.

Adolescent↗
PubMed1998

Spontaneous abnormal involuntary movements in first-episode schizophrenia and schizophreniform disorder: baseline rate in a group of patients from an Irish catchment area.

OBJECTIVE: This study investigated the rate of spontaneous abnormal involuntary movements in a group of patients presenting with a first episode of schizophrenia or schizophreniform psychosis. METHOD: Seventy-nine patients with a first episode of schizophrenia or schizophreniform psychosis who presented to a catchment area psychiatric service over a 3-year period, and who were neuroleptic-naive or had been medicated for less than 1 month, were examined for the presence of involuntary movements with use of the Abnormal Involuntary Movement Scale. RESULTS: Six patients (7.6%) had spontaneous dyskinesia as defined by the criteria of Schooler and Kane, and nine other patients had mild orofacial involuntary movements. The patients with spontaneous dyskinesia had completed significantly fewer years of education than the patients without dyskinesia. Spontaneous involuntary movements were unrelated to age at presentation for treatment. CONCLUSIONS: Spontaneous abnormal involuntary movements were evident among a proportion of patients with first-episode schizophrenia or schizophreniform psychosis at baseline presentation and were associated with reduced educational attainment. This finding supports previous suggestions that abnormal involuntary movements in schizophrenia may be related to the pathophysiology of the illness and therefore cannot be attributed entirely to the adverse effects of neuroleptic medication.

Adult↗
PubMed1998

The S. cerevisiae CLU1 and D. discoideum cluA genes are functional homologues that influence mitochondrial morphology and distribution.

The cluA gene, encoding a novel 150 kDa protein, was recently characterized in Dictyostelium discoideum; disruption of cluA impaired cytokinesis and caused mitochondria to cluster at the cell center. The genome of Saccharomyces cerevisiae contains an open reading frame (CLU1) that encodes a protein that is 27% identical, 50% similar, to this Dictyostelium protein. Deletion of CLU1 from S. cerevisiae did not affect cell viability, growth properties, sporulation efficiency, or frequency of occurrence of cells lacking functional mitochondria. However, in clu1Delta cells the mitochondrial reticulum, which is normally highly branched, was condensed to one side of the cell. Transformation of cluA- Dictyostelium mutants with the yeast CLU1 gene yielded amoebae that divided normally and had dispersed mitochondria. The mitochondria in cluA- Dictyostelium cells complemented with CLU1 were not as widely scattered as in cluA+ Dictyostelium cells, but formed loose clusters throughout the cytoplasm. These results indicate that the products of the CLU1 and cluA genes, in spite of their limited homology, are functional homologues.

Amino Acid Sequence↗
PubMed1997

The cluA- mutant of Dictyostelium identifies a novel class of proteins required for dispersion of mitochondria.

The cluA gene of Dictyostelium discoideum encodes a novel 150-kDa protein. Disruption of cluA results in clustering of mitochondria near the cell center. This is a striking difference from normal cells, whose mitochondria are dispersed uniformly throughout the cytoplasm. The mutant cell populations also exhibit an increased frequency of multinucleated cells, suggesting an impairment in cytokinesis. Both phenotypes are reversed by transformation of cluA- cells with a plasmid carrying a constitutively expressed cluA gene. The predicted sequence of the cluA gene product is homologous to sequences encoded by open reading frames in the genomes of Saccharomyces cerevisiae and Caenorhabditis elegans, but not to any known protein. The only exception is a short region with some homology to the 42-residue imperfect repeats present in the kinesin light chain, which probably function in protein-protein interaction. These studies identify a new class of proteins that appear to be required for the proper distribution of mitochondria.

Amino Acid Sequence↗
PubMed1997

Comparison of Neoral and Sandimmun cyclosporin A pharmacokinetic profiles in young renal transplant recipients.

A major factor influencing whole blood cyclosporin A levels in young children with renal transplants is the variable absorption of Sandimmun (SIM). Neoral (NEO) is a new microemulsion of cyclosporin A (CYA) that has been reported to have better absorption characteristics. We compared the pharmacokinetics of SIM and NEO in nine renal transplant recipients aged less than 11 years (range 4.8-10.9 years) and observed clinical parameters during 6 months of NEO therapy. Median CYA dosage was 149 mg/m2 per day (range 98-226). We observed an increase in the maximum CYA concentration (Cmax) of 114%, an increase in area under the curve (AUC) of 71% and the time to reach Cmax was reduced from 1.75 h to 1.25 h with NEO, while 12-h trough levels (C12 h) did not change significantly. AUC correlated with C12 h for SIM (r2 = 0.833) and NEO (r2 = 0.699) and also C1.5 h for NEO (r2 = 0.775). During 24 weeks' follow-up, the coefficient of variation of CYA levels was lower for NEO (13%) than for SIM (20%). Although CYA dosages at the start and the end of 6 months on NEO were similar, only one patient was maintained on a constant dose. Four patients had acute reversible rises in plasma creatinine which responded to a 11% reduction in NEO dose; their increase in AUC was greater than those patients not showing a rise in plasma creatinine. Overall, median plasma creatinine was unchanged at the end of the study. NEO was well tolerated by the patients; temporary nausea and headache were experienced by three patients and one of them stopped NEO after 20 days. Other biochemical parameters were not significantly different on NEO.

Area Under Curve↗
PubMed1997

For debate. Local government and the National Health Service: the new agenda.

There are some interesting paradoxes in the relationship between local government and the National Health Service (NHS). Local government is responsible for a range of major services, many of which relate to health broadly defined. The NHS provides many services which are often popularly thought to be part of local government (and, indeed, in many countries are). Local government prides itself on its 'localness'; the NHS, with its services delivered in a very local fashion for the most part, cannot quite decide whether it is a national service or a local one. Yet these two major agencies of governance and public service provision often seem unable to work very well together. In the interests of good government, both agencies need to work together where their interests coincide or abut one another. Differences of perspective, priority, culture and style need to be recognized but resolved. Opportunities for joint working need to be grasped and the experience built on. The paper looks at a series of issues and opportunities which bring local government and the NHS together. They create an incentive to improve working relationships; at the same time they suggest an agenda of future possibilities.

Humans↗
PubMed1997

Improving outpatient clinic efficiency using computer simulation.

To assess and plan alterations in outpatient clinic structure, produces a computer simulation of an outpatient clinic based on detailed time and role measurements from the authors' clinic. The stimulation which used an object-oriented design method is able to indicate the impact of changes in clinic structure using patient and doctor waiting times in clinic as endpoint measures. The effects of changes in clinic size, consultation time, patient mix, appointment scheduling and non-attendance were examined. We found that patient waiting time could be shortened considerably by using an optimizing appointment scheduler to determine appointment intervals. Clinic mix influences patient waiting time, which was shorter with a 1 in 4 ratio of new to follow-up patients. In mixed clinics, new patients appointments are optimally spread throughout the clinic to reduce patient waiting time. In all new or all follow-up clinics, waiting time is improved if the appointment interval reflects the consultation time. Computer modelling can help in optimizing clinic management so improving the delivery of care in outpatient services.

Appointments and Schedules↗
PubMed1997

Caregivers' perceptions following gastrostomy in severely disabled children with feeding problems.

Feeding difficulties are common in neurologically impaired children, often leading to great distress and frustration in the child and family. A gastrostomy may be advocated if oral intake is inadequate causing poor weight gain or when there is significant aspiration during feeding, or if feeding is very distressing. To find out if caregivers were happy with the outcome of gastrostomy (with fundoplication, when indicated), a 35-item questionnaire was developed and sent to 38 of them. Twenty-nine replies were received and appeared to be representative of the whole group. Coughing, choking, and vomiting improved in most cases. Weight gain improved in all in whom it had been a problem. In the majority, it became easier to give the children their medications although control of epilepsy was unchanged overall. Time spent feeding the child was reduced and many caregivers had more time to devote to other children and themselves. Only one parent regretted the operation. In children with severe disability and feeding problems, a gastrostomy (with fundoplication if there is significant reflux) can reduce symptoms of vomiting, coughing, and choking, help growth and improve quality of life in the child, when patients are properly selected.

Adolescent↗
PubMed1997

Reasons for tooth extractions in dental practices in Ontario, Canada according to tooth type.

In a study of tooth extractions in general dental practices in Ontario, Canada, 165 dental practitioners provided information on 6134 patients attending during a reference week. Of these, 11.6 per cent of patients had one or more permanent teeth extracted. Periodontal disease was given as the reason for 35.9 per cent of these extractions and caries for 28.9 per cent. Analysis by tooth type showed that third molars were the most common tooth type extracted. However, there were differences in the types of teeth extracted by age. Posterior teeth were most frequently lost by the younger age groups and anterior teeth by older subjects. There were also differences in the reasons for the loss of different tooth types. A comparison of these results with those of a similar study in Scotland suggests that age and tooth type does not account for the excess of extractions due to periodontal disease in this Canadian population. Differences in practice patterns and attitudes towards the retention of teeth may be contributing factors.

Adolescent↗
PubMed1997

The pattern-of-care model: a tool for planning community mental health services.

In periods of change, psychiatric services must project outcomes of decisions about service innovations and reductions, including budgetary implications. To support such decision making, a public-sector psychiatric service in Melbourne, Victoria, Australia, developed a modeling tool that combines data from its service activity database and budgetary information with modeling techniques based on use of a spreadsheet. The model is based on clients' use of three major service components: the inpatient unit, continuing clinical care and consultancy services, and crisis assessment and treatment services. It classifies clients according to patterns of care-that is, whether they used one, two, or three of the components, in various combinations. The authors report service use and financial data derived from the model for the financial year 1992-1993. They describe two scenarios for using the model to project changes in patterns of care and costs when new services are implemented. Such a model can clarify costs, including opportunity costs, of management decisions and facilitate participation of senior clinicians in active service planning within the realities of budgetary constraints.

Budgets↗