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Biomedical subjects

C M Harris

Publications and source records attributed to C M Harris.

At least 109 records · Page 6Linked to original sources
PubMed1995

Low income scheme index: a new deprivation scale based on prescribing in general practice.

OBJECTIVES: To describe and validate a new deprivation index, based on the percentage of prescribed items exempt from the prescription charge under the low income scheme, at both family health services authority and practice level. DESIGN: Comparison of the index with three other deprivation indices and correlation of index values with the use of drugs given for conditions with known social class gradients. SETTING: All 90 family health services authorities and 7619/9289 practices in England. RESULTS: The ranking of family health services authorities on the new index correlated highly with rankings on the other indices. Values in relation to the use of drugs given for conditions with known social class gradients were in the predicted direction at both family health services authority level and practice level; correlation was highly significant at the authority level, but less significant at practice level. CONCLUSIONS: The new index provides a good measure of deprivation at family health services authority level, and at practice level the results are sufficiently encouraging to warrant further research. It provides the best available instrument for relating deprivation to the use of drugs in any population that can be defined by prescribing data, but an attempt to use it in determining allocation of resources would at this stage be premature.

Drug Costs↗
PubMed1995

Does saccadic undershoot minimize saccadic flight-time? A Monte-Carlo study.

Visually guided saccades to single targets undershoot by about 10% of the target distance, and require additional secondary saccades to foveate the target. We examine theoretically the hypothesis that undershooting is an economical strategy for maximizing the time for clear vision by minimizing saccadic flight-time. Using a simple stochastic model, Monte-Carlo simulations show that when the standard deviation of saccadic error is about 10% of the target distance the optimal gain of primary saccades is about 0.93-0.97 depending on the main sequence for saccade duration. When the standard deviation of saccadic error is large, as occurs in the human infant, the optimal gain decreases to about 0.6, which agrees with empirical observations. We conclude that saccadic undershoot is consistent with an adaptive controller that attempts to minimize total saccadic flight-time during sequences, rather than retinal error. The ethology and physiology of such a controller is discussed in the context of visual scanning and visual development.

Fixation, Ocular↗
PubMed1995

The prevalence and prophylaxis of gout in England.

The prevalence of gout in England was reported as having nearly doubled in the 1970s to about 3 per 1000, and it is possible that it has continued to increase. There may also have been some change in the level of prophylactic therapy compared with the 44.8% recorded in 1979. In this study, data were provided from their morbidity registers by 40 volunteer practices with a combined population of over 300,000 patients. Analyses of prevalence by age and sex, and of the extent of prophylaxis were made. The male:female ratio and the increase with age found were in line with earlier work, but overall prevalence was much higher at almost 10 per 1000. There was considerable inter-practice variation: 20% of this could be accounted for by the age and sex structure of the practice populations, but neither economic status nor broad geographical factors appeared to be significant, and it did not appear to be due to variation between practices in the level of special interest in gout. Prophylactic therapy--almost entirely allopurinol--was being prescribed for 48% of the sufferers; though practices varied widely in their propensity to give it, as a group the amount of allopurinol they used was close to the national average. The increase found in the prevalence of gout may be related to an increase in obesity in the population.

Adult↗
PubMed1995

An efficient route to N6 deoxyadenosine adducts of diol epoxides of carcinogenic polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons are metabolized to a wide variety of oxidized derivatives, including highly reactive diol epoxides which alkylate DNA. The reaction lacks regio- or stereospecificity but occurs primarily at the exocyclic amino groups of deoxyguanosine and deoxyadenosine. An efficient route to N6 adducts of deoxyadenosine is described using as examples those arising from trans opening of the anti-tetrahydrodiol epoxides of naphthalene, benzo[a]pyrene, and benzo[c]phenanthrene. The adducts were synthesized in 50-92% yields by reaction of 6-fluoropurine 2'-deoxyriboside with aminotriols formed by trans opening of racemic dihydrodiol epoxides using liquid NH3. The diastereomeric adducts were separated by HPLC and their absolute configurations were assigned by circular dichroism. 1H NMR studies revealed significant differences in conformation of the tetrahydroaromatic ring between the sterically unrestricted naphthalene derivative and the sterically congested derivatives of benzo[a]pyrene and benzo[c]phenanthrene. These differences may have a bearing on the higher carcinogenicity shown by the latter hydrocarbons. Undecadeoxyoligonucleotides bearing regio- and stereochemically defined adenine N6-anti-trans-benzo[a]pyrene adducts have been prepared.

Base Sequence↗
PubMed1995

The optokinetic response differences between congenital profound and nonprofound unilateral visual deprivation.

BACKGROUND: The occurrence of monocular naso-to-temporal optokinetic nystagmus (OKN) asymmetry, as a reflection of the immature oculomotor system in infants, and its persistence with early onset monocular visual deprivation, is well known. This asymmetry has been linked with poor binocular function and attributed to disruption of the development of binocular cortical projections to the pretectum. Optokinetic nystagmus symmetry in patients with congenital uniocular total pattern vision deprivation has not been fully investigated. METHODS: The authors compared the optokinetic responses in six children with "profound" uniocular visual deprivation, who were born with untreated conditions (microphthalmos and persistent hyperplastic primary vitreous), with ten aphakic children treated early for congenital unilateral cataracts (nonprofound unilateral visual deprivation). Eye movements were recorded using dc-electro-oculography, and OKN was elicited using a full-field patterned curtain. Flash and pattern visual-evoked responses were also measured in each subject. RESULTS: Latent nystagmus was present in six children in the nonprofound group, whereas none was detected in the profound group. All children in the nonprofound group showed statistically significant monocular naso-to-temporal asymmetry for either eye. Subjects in the profound group had symmetric OKN. CONCLUSIONS: The authors conclude that unequal input from the two eyes and interocular rivalry lead to OKN asymmetry. Their results suggest that if vision from one eye is so negligible that it does not compete with the neuroanatomic connections of the fellow eye, then the input from this eye remains undisturbed, and OKN remains symmetric.

Adolescent↗
PubMed1995

Neuroradiological and eye movement correlates in children with intermittent saccade failure: "ocular motor apraxia".

Ocular motor apraxia (OMA) is a clinical sign involving the intermittent inability to initiate saccades, and a failure of quick phases during optokinetic nystagmus (OKN) and vestibular nystagmus (VN). Some patients have no other associated abnormalities (idiopathic), whereas others have a variety of neurological conditions. We quantified the severity of the saccade failure and correlated it with neuro-radiological and other oculomotor findings in 62 children (aged 17 days - 14 years). Saccades, smooth pursuit, OKN and VN were recorded using electrooculography and the extent of "locking up" (absent quick phases during OKN and VN) was measured. Saccades were usually hypometric. Pursuit and OKN gains were normal in the majority of the idiopathic cases but were low in those with other neurological conditions. Twenty-four patients had essentially normal scans, whereas 38 had abnormal scans: Delayed myelination, cerebellar abnormalities (particularly involving the vermis), and agenesis of the corpus callosum were the most common findings. A significant positive correlation was present between increasing neuro-radiological deficits and severity of "locking up" during OKN. Principal component analysis showed that brainstem and cerebellar vermis abnormalities were the main factors involved. A pathophysiological basis of OMA is discussed in the light of animal and clinical studies.

Adolescent↗
PubMed1995

Synthesis and characterization of the human elastin W4 sequence.

Following the nomenclature of Sandberg, the W4 sequence of human elastin, [sequence: see text], has been synthesized by solid-phase methods and characterized by carbon-13 nuclear magnetic resonance, amino-acid analysis, mass spectra and elemental analysis. This sequence was then polymerized to greater than 50 kDa as determined by retention in 50 kDa molecular weight cut-off dialysis tubing. It has been successfully cross-linked by gamma-irradiation (20 Mrad) to form an elastomeric matrix, designated as X20-poly(W4). Physical characterizations such as stress/strain, thermolelasticity, acid-base titration and inverse temperature transition studies have been carried out on this elastomer, which is homologous to the striking, poly(VPGVG), W4 sequence of bovine and porcine elastins. These results are compared with previous results on the polypentapeptide of elastin, (VPGVG)n, and it has been demonstrated that X20-poly(W4) also is a dominantly entropic elastomer. Finally, the working model for the structure of this human elastin sequence was derived computationally using molecular mechanics and dynamics calculations. Thus the human W4 sequence appears to be structurally and functionally equivalent to the bovine and porcine W4 sequences in spite of the less regular repeating pentamer sequence.

Amino Acid Sequence↗
PubMed1995

The effects on prescribing patterns and costs of having a special interest in asthma.

To define the characteristics of general practices with a special clinical interest in asthma and to estimate the resulting extra prescribing costs, we sent a postal questionnaire to all English practices containing members of the General Practitioners in Asthma Group. Item and cost comparisons for 24 PACT (prescribing analysis and cost) aggregates were made between practices who had operated an agreed, written management plan for asthma before 1 April 1990 and all other practices in their respective Family Health Services Authorities. One hundred and sixty-three practices with GPIAG members responded (70%), of which 26 filled the management plan requirement. These 26 practices showed evidence of significantly better asthma care provision than the remainder of the sample. Their prescribing costs were significantly higher for respiratory drugs (median 37% higher) but lower in other drug categories. For respiratory drugs, costs were significantly higher for inhaled adrenoceptor stimulants, steroid inhalers, large spacers, and peak flow meters, but lower for cough medicines and systemic nasal decongestants: the number of items prescribed showed similar patterns. The prescribing costs of practices claiming a special interest in asthma are likely to show higher respiratory drug costs, but overall prescribing costs showed no increase in the practices studied.

Anti-Asthmatic Agents↗
PubMed1995

Information requirements for an integrated delivery system.

The health care marketplace in the United States is rapidly changing, resulting in more integrated delivery systems that will assume the financial risk for the clinical care of a mostly capitated population. The information requirements of a successful integrated delivery system must include: document management; orders and results management; clinical protocols with embedded case management tools; clinical decision support; and administrative practice management functions such as enrollment management, scheduling, and utilization management. These requirements can only be fulfilled using new information technologies, modified assessment strategies, and migration plans grounded in process analysis and re-engineering.

Delivery of Health Care, Integrated↗
PubMed1994

Measuring prescribing: the shortcomings of the item.

OBJECTIVES: To assess the validity of the item as a measure of the volume of a drug prescribed; and to investigate the possibility that higher quantities per item are prescribed for patients who are not exempt from the prescription charge. DESIGN: Five substudies. For the first, a frequency distribution was derived of the different quantities per item of 10 commonly used drugs prescribed by 20 randomly selected practices in each of five family health service authority areas. For the second, the variation in average quantity per item for the same drugs in the same practices was calculated. For the third and fourth, variation in average quantity per item for 90 commonly used drugs was calculated for all 90 family health service authorities and for all 14 regional health authorities in England. For the fifth, the average quantity per item for each of the 90 drugs was regressed on the percentage of items exempt from the prescription charge, at family health service authority level, and the percentage of variation explained by the regression found. MAIN OUTCOME MEASURE: Distribution of quantity per item; variation in average quantity per item between the practices, between family health service authorities, and between regions; and percentage of variation between family health service authorities accounted for by exemption from the prescription charge. RESULTS: Wide variation was found in the quantities per item prescribed by the practices, and in the average quantity per item between practices and between family health service authorities. No family health service authority was consistently high or low in quantity per item across the 90 drugs. Variation in average quantity per item was less at regional than at family health service authority level, though still high for many of the drugs. The proportion of variation accounted for by exemption from prescription charges ranged from 0% to 49% across the 90 drugs. CONCLUSIONS: The item is unsuitable as a measure of prescribing volume, even at regional level: a new measure, based on standard daily dosages, is needed. The percentage of the variation in quantity per item accounted for by exemption is inconsistent, and in over half the 90 drugs it was below 20%--therefore it is not a useful predictor.

Drug Prescriptions↗
PubMed1994

The use of a clinical case study in a clinical information system selection process.

The University of Pennsylvania Health System recently underwent an extensive selection process for a new clinical information system. In addition to a traditional system selection approach, a clinical case study was utilized during our selection process. This was done in an effort to better prepare the clinicians involved in the selection process, as well as to help identify key operational issues that the institution would need to resolve, related to the design and implementation of a new clinical system. We wil describe here the reasons this approach was chosen, how the case study was utilized, and provide an assessment of its usefulness.

Clinical Laboratory Information Systems↗