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Biomedical subjects

I White

Publications and source records attributed to I White.

At least 19 recordsLinked to original sources
PubMed2003

Deodorants: an experimental provocation study with cinnamic aldehyde.

BACKGROUND: Axillary dermatitis is common and overrepresented in individuals with contact allergy to fragrances. Many individuals suspect their deodorants to be the incriminating products. OBJECTIVE: Our aim was to investigate the significance of cinnamic aldehyde in deodorants for the development of axillary dermatitis when used by individuals with and without contact allergy to cinnamic aldehyde. METHODS: Patch tests with deodorants and ethanol solutions with cinnamic aldehyde, and repeated open application tests with roll-on deodorants without and with cinnamic aldehyde at different concentrations, were performed in 37 patients with dermatitis, 20 without and 17 with contact allergy to cinnamic aldehyde. RESULTS: A repeated open application test with positive findings was noted only in patients hypersensitive to cinnamic aldehyde (P <.001) and only in the axilla to which the deodorants containing cinnamic aldehyde had been applied (P <.001). CONCLUSION: Deodorants containing cinnamic aldehyde in the concentration range 0.01% to 0.32%, used twice daily on healthy skin, can elicit axillary dermatitis within a few weeks.

Acrolein↗
PubMed2001

Correcting for measurement error in binary and continuous variables using replicates.

Measurement error in exposures and confounders leads to bias in regression coefficients. It is possible to adjust for this bias if true values or independent replicates are observed on a subsample. We extend a method suitable for quantitative variables to the situation where both binary and quantitative variables are present. Binary variables with independent replicates introduce two extra problems: (i) the error is correlated with the true value, and (ii) the measurement error probabilities are unidentified if only two replicates are available. We show that - under plausible assumptions - adjustment for error in binary confounders does not need to address these problems. The regression coefficient for a binary exposure is overadjusted if methods for continuous variables are used. Correct adjustment is possible either if three replicates are available, or if further assumptions can be made; otherwise, bounds can be put on the correctly adjusted value, and these bounds are reasonably close together if the exposure has prevalence near 0.5.

Bias↗
PubMed2001

Competing risks analysis of patients with osteosarcoma: a comparison of four different approaches.

In failure time studies involving a chronic disease such as cancer, several competing causes of mortality may be operating. Commonly, the conventional statistical technique of Kaplan-Meier, which is only meaningfully interpreted by assuming independence of failure types and the censoring mechanism, is employed in clinical research involving competing risks data. Some authors have advocated the use of a cause-specific cumulative incidence function which takes into account the existence of other events within a competing risks framework, without making any assumption about independence. Lunn and McNeil have proposed an approach based on an extension of the Cox proportional hazards regression, which enables direct comparisons between failure types. We have extended this approach to estimate cause-specific cumulative incidence. As it is often not easy to follow competing risks methodology in the literature, this paper sets out systematically the assumptions made and the steps taken to implement four different methods of analysing competing risks data using cumulative incidence rates or the Kaplan-Meier estimates of cause-specific failure probabilities. The data obtained from a randomized trial of patients with osteosarcoma were used to compare these four approaches. As illustrated using the osteosarcoma data, the estimates of the classical Kaplan-Meier methods have larger numerical values than the cause-specific cumulative incidence. On the other hand, estimates of the cause-specific cumulative incidence rates from the conventional method and the modified Cox method are highly comparable.

Adolescent↗
PubMed2001

The time-dose-response relationship for elicitation of contact dermatitis in isoeugenol allergic individuals.

The elicitation response in allergic contact dermatitis is dose dependent, but the time-concentration relationship for elicitation has not previously been described. In this study 27 isoeugenol-sensitive patients participated in serial dilution patch tests with isoeugenol and a double-blinded Repeated Open Application Test (ROAT) using two concentrations of isoeugenol, 0.2 and 0.05%. Seven controls without isoeugenol allergy were also included. The participants applied 3.72 +/- 1.57 (mean +/- SD) mg/cm(2) of coded isoeugenol solutions twice a day to a 3 x 3 cm(2) area on the volar aspect of the right and left arm, respectively. For each test site the applications continued until a reaction appeared or for a maximum of 28 days. The minimal criteria for a positive reaction regarded as allergic contact dermatitis was persistent erythema at the ROAT test site. All controls were negative and 16/24 (66.7%) of the included isoeugenol-sensitive subjects showed a positive ROAT to the 0.2% solution within the study period (Fisher's test, p = 0.0024). Ten of the positive patients also reacted to the 0.05% solution. The median number of days until a positive reaction to the 0.2% solution was 7 days and was 15 days for the 0.05% solution. There was a highly significant correlation between the patients' patch test threshold and the number of days until a positive ROAT. In conclusion, the time until an isoeugenol allergic individual reacts in a ROAT depends on the individual sensitivity as well as the exposure concentrations; for low concentrations of the allergen or low degree of sensitivity, the allergic contact dermatitis may develop after several weeks of exposure. Therefore, a negative ROAT after 7 days may be a false negative.

Administration, Topical↗
PubMed2001

Maternal uniparental heterodisomy for chromosome 2: detection through 'atypical' maternal AFP/hCG levels, with an update on a previous case.

We report a case of maternal uniparental disomy 2, detected through routine screening of placental karyotypes following the finding of 'atypical' AFP/hCG levels in the second trimester, with intrauterine growth retardation (IUGR) but otherwise normal outcome at term. Although the child remained small, subsequent early physical and mental development has also been normal. Additionally, we report long-term follow-up of an earlier case, again with relatively normal physical and mental development. The significance of atypical AFP/hCG results and the predictive value of prenatal testing for UPD2 in trisomy 2 confined placental mosaicism (CPM) cases are discussed.

Adult↗
PubMed2001

Studies on dental erosion: an in vitro model of root surface erosion.

Most research on dental erosion has focused on erosion in enamel. However, the increasing retention of teeth into old age has increased the potential for root surface erosion. The nature and kinetics of root surface erosion have not yet been adequately explored. The objective of this project was to develop an in vitro model of root surface erosion in order to investigate the polarised light microscopy of controlled erosion and the histology and rate of demineralisation of this process in root cementum/dentine. The results demonstrate a process quite different in outcome from that in enamel erosion. Erosion results in loss of volume of enamel. However, it leaves a root surface softened though with little volume loss so long as the demineralised collagen remains hydrated. The polarised light histology was similar to that seen in root surface caries. The rate of erosive demineralisation of tooth roots by selected acids was investigated, with differing rates of demineralisation similar to that seen in enamel erosion observed. The process of erosion showed evidence of significant diffusion control.

Acetic Acid↗
PubMed2001

Suicidal behaviour in psychosis: prevalence and predictors from a randomised controlled trial of case management: report from the UK700 trial.

BACKGROUND: It is unclear whether intensive case management influences the prevalence of suicidal behaviour in patients with psychosis. AIMS: To compare the effect of intensive case management and standard care on prevalence of suicidal behaviour in patients with chronic psychosis. METHOD: Patients with established psychosis (n = 708) were randomised either to intensive case management or to standard care. The prevalence of suicidal behaviour was estimated at 2-year follow-up and compared between treatment groups. Suicide attempters and non-attempters were compared on multiple socio-demographic and clinical variables to identify predictors of suicidal behaviour. RESULTS: There was no significant difference in prevalence of suicidal behaviour between treatment groups. Recent attempts at suicide and multiple recent hospital admissions best predicted future attempts. CONCLUSIONS: Intensive case management does not appear to influence the prevalence of suicidal behaviour in chronic psychosis. Predictors identified in this study confirm some previous findings.

Adolescent↗
PubMed2000

Diagnostic value of the DSM and ICD categories of psychosis: an evidence-based approach. UK700 Group.

BACKGROUND: It is generally assumed that the distinction between affective and non-affective psychosis occasioned by modern diagnostic criteria provides a useful symptomatic contrast. METHOD: In a sample of 708 patients with chronic psychosis, the distinction of lifetime DSM-III-R and ICD-10 diagnoses of affective versus non-affective psychosis was used as a diagnostic test to detect lifetime presence of depressive, manic, positive, negative and disorganisation symptoms. RESULTS: A manic or depressive affective diagnosis was a perfect test to diagnose the presence of manic and depressive symptoms, as evidenced by very high diagnostic likelihood ratios. However, this test result was based solely on the inclusion criterion that patients with affective psychosis must have affective symptoms (guaranteeing high specificity and high likelihood ratios), and ignored the fact that patients with non-affective psychosis also had high affective symptom scores (low sensitivity). Furthermore, a non-affective psychotic diagnosis was a very poor test to diagnose correctly the presence of positive, negative and disorganisation symptoms in comparison with an affective psychotic diagnosis. In general, the DSM-III-R categories performed somewhat better as a diagnostic test than those of ICD-10. CONCLUSION: The evidence for true diagnostic value of the distinction between affective and non-affective psychotic diagnoses is weak. Rather, the distinction appears to obscure natural overlap between the symptom dimensions of the different diagnostic categories.

Adolescent↗
PubMed2000

Stereoselective loss of righting reflex in rats by isoflurane.

BACKGROUND: Although it is accepted widely that optically active intravenous general anesthetics produce stereoselective effects in animals, the situation regarding volatile agents is confused. Conventional studies with scarce isoflurane enantiomers have been limited to small numbers of animals and produced conflicting results. By injecting these volatile enantiomers intravenously, however, it is possible to study large numbers of animals and obtain reliable results that can help to identify the molecular targets for isoflurane. METHODS: Pure isoflurane enantiomers were administered intravenously to rats after solubilization in a lipid emulsion. The ability of each enantiomer to produce a loss of righting reflex was determined as a function of dose, and quantal dose-response curves were constructed. In addition, sleep times were recorded with each enantiomer. Chiral gas chromatography was used to measure relative enantiomer concentrations in the brains of rats injected with racemic isoflurane. RESULTS: The S(+)-enantiomer was 40 +/- 8% more potent than the R(-)-enantiomer at producing a loss of righting reflex. The S(+)-enantiomer induced longer sleep times (by about 50%) than did the R(-)-enantiomer. Rats anesthetized by a dose of racemic isoflurane sufficient to achieve a half-maximal effect had essentially identical brain concentrations of the two enantiomers. CONCLUSIONS: The S(+)-enantiomer of the general anesthetic isoflurane is significantly (P < 0.001) more potent than the R(-)-enantiomer at causing a loss of righting reflex in rats. This confirms the view that isoflurane acts by binding to chiral sites. The observed degree of stereoselectivity provides a useful guide for ascertaining from in vitro experiments which molecular targets are most likely to play major roles in the loss of righting reflex caused by isoflurane.

Anesthetics, Inhalation↗
PubMed1999

Intensive versus standard case management for severe psychotic illness: a randomised trial. UK 700 Group.

BACKGROUND: Case management has increasingly been the recommended approach to care for severely mentally ill patients since the number of psychiatric beds has decreased. Despite equivocal results, in the UK and Europe, this approach is becoming accepted policy. We assessed the effect of smaller case loads. METHODS: We randomly assigned 708 psychotic patients in four centres standard case management (355 patients, case load 30-35 per case manager) or intensive case management (353 patients, case load 10-15 per case manager). We measured clinical symptoms and social functioning at baseline, 1 year, and 2 years. The impact of treatment on hospital use was assessed at 2 years by subgroup analyses for Afro-Caribbean and for severely socially disabled patients. Analysis was by intention to treat. FINDINGS: There was no significant decline in overall hospital use among intensive-case-management patients (mean 73.5 vs 73.1 days in those who received standard care [SD 0.4, 95% CI -17.4 to 18.1]), nor were there any significant gains in clinical or social functioning. There was no evidence of differential effect in Afro-Caribbean patients or the most socially disabled patients. INTERPRETATION: In well-coordinated mental-health services, a decline in case load alone does not improve outcome for these patients. Mental-health planners may need to pay more attention to the content of treatment rather than changes in service organisation.

Adolescent↗
PubMed1999

A comparison of the utility of dimensional and categorical representations of psychosis. UK700 Group.

BACKGROUND: The usefulness of any diagnostic scheme is directly related to its ability to provide clinically useful information on need for care. In this study, the clinical usefulness of dimensional and categorical representations of psychotic psychopathology were compared. METHOD: A total of 706 patients aged 16-65 years with chronic psychosis were recruited. Psychopathology was measured with the Comprehensive Psychopathological Rating Scale (CPRS). Lifetime RDC, DSM-III-R, and ICD-10 diagnoses and ratings of lifetime psychopathology were made using OPCRIT. Other clinical measures included: (i) need for care; (ii) quality of life; (iii) social disability; (iv) satisfaction with services; (v) abnormal movements; (vi) brief neuropsychological screen; and (vii) over the last 2 years--illness course, symptom severity, employment, medication use, self-harm, time in hospital and living independently. RESULTS: Principal component factor analysis of the 65 CPRS items on cross-sectional psychopathology yielded four dimensions of positive, negative, depressive and manic symptoms. Regression models comparing the relative contributions of dimensional and categorical representations of psychopathology with clinical measures consistently indicated strong and significant effects of psychopathological dimensions over and above any effect of their categorical counterparts, whereas the reverse did not hold. The effect of psychopathological dimensions was mostly cumulative: high ratings on more than one dimension increased the contribution to the clinical measures in a dose-response fashion. Similar results were obtained with psychopathological dimensions derived from lifetime psychopathology ratings using the OCCPI. CONCLUSIONS: A dimensional approach towards classification of psychotic illness offers important clinical advantages.

Adolescent↗
PubMed1999

To what extent does symptomatic improvement result in better outcome in psychotic illness? UK700 Group.

BACKGROUND: The effectiveness of therapeutic interventions in psychosis is increasingly reported in terms of reductions in different symptom dimensions. It remains unclear, however, to what degree such symptomatic changes are accompanied by improvement in other measures such as service use, quality of life, and needs for care. METHODS: A sample of 708 patients with chronic psychotic illness was assessed on three occasions over 2 years (baseline, year 1 and year 2). A multilevel analysis was conducted to examine to what degree reduction in psychopathological scores derived from factor analysis of the Comprehensive Psychopathological Rating Scale (CPRS), was associated with improvement in service use, disability, subjective outcomes and measures of self-harm. RESULTS: Reduction in positive, negative, depressive and manic symptoms over the study period were all independently associated with lessening of social disability. Reduction in negative symptoms, and to a lesser extent in positive and manic symptoms, was associated with less time in hospital and more time living independently, whereas changes in positive and manic symptoms resulted in fewer admissions. Subjective outcomes such as improvement in quality of life, perceived needs for care and dissatisfaction with services showed the strongest associations with reduction in depressive symptoms. Reduction in positive symptoms was associated with decreased likelihood of parasuicide. Results did not differ according to diagnostic category. CONCLUSION: The findings suggest that changes in distinct psychopathological dimensions independently and differentially influence outcome. Therapeutic interventions aimed at reducing symptoms of more than one dimension are likely to have more widespread effects.

Adolescent↗
PubMed1999

Prevalence and predictors of parasuicide in chronic psychosis. UK700 group.

OBJECTIVE: This study estimates the prevalence of and risk factors for parasuicide in a large community-based sample of patients with chronic psychosis. METHOD: A total of 704 subjects with chronic psychosis were interviewed using a battery of instruments. The 2-year prevalence of parasuicide was estimated and a comparison was made between attempters and nonattempters on a wide range of sociodemographic and clinical variables. RESULTS: The 2-year prevalence of parasuicide was 18.8%. Attempters were significantly more likely to be younger, of white ethnic origin, to have a diagnosis of affective disorder, to be currently depressed, to have experienced more auditory hallucinations and to have received treatment with antipsychotic drugs for a longer period. CONCLUSION: Parasuicide was found to present a considerable clinical problem in this group. Continual risk assessment is essential to reduce this unacceptably high rate.

Adolescent↗