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Biomedical subjects

C Irvine

Publications and source records attributed to C Irvine.

At least 19 recordsLinked to original sources
PubMed2004

The clinical implications of the collapsed cone planning algorithm.

AIMS: The accuracy of computer treatment planning systems is important in achieving clinically acceptable dose distributions. The pencil beam (PB) algorithm on Helax-TMS is currently used for all clinical treatment planning at the two centres involved in this study. However, it has been shown that the Helax-TMS collapsed cone (CC) algorithm is more accurate in regions of heterogeneity, such as the thorax, and head and neck. The aim of this study was to show the actual dose delivered to the patient when treating with a Helax-TMS PB plan, by using the corresponding Helax-TMS CC plan as the reference standard. MATERIALS AND METHODS: Thirty PB treatment plans (for lung and oesophageal treatments) were recalculated using the CC algorithm, and plans were then compared. RESULTS: The number of monitor units required to deliver the prescription dose differed between algorithms, by up to 3.4%. In most cases, the CC algorithm calculated more monitor units than the PB, indicating under-dosage at the prescription point during treatment. The dose distributions also seemed less homogeneous when calculated using the CC algorithm. The minimum dose to the planning target volume (PTV) was lower than the PB plan suggested in every case, by up to 23.2%. ICRU homogeneity requirements (i.e. a minimum 95% of the prescription dose in the PTV) were not met in any of the cases. Even with some attempts at optimisation, conformance to these requirements was difficult. CONCLUSION: The CC algorithm has several factors limiting its suitability for routine clinical use. However, it is an important milestone in radiotherapy treatment planning, and should be used to show expected changes in computer planned dose distributions with new accurate dose algorithms. It is worthwhile considering dose homogeneity requirements well before the advent of anticipated Monte Carlo-based models.

Algorithms↗
PubMed2001

The Interdisciplinary Generalist Curriculum Project at the University of California, San Francisco.

The Interdisciplinary Generalist Curriculum (IGC) Project came at a pivotal time in curriculum development at the University of California, San Francisco, School of MEDICINE: In the three years prior to the project, the curriculum committee had considered implementation of early longitudinal clinical experiences. This had not been proposed as a primary care experience. Introduction of generalist skills, with the goal of increasing numbers of students choosing generalist residencies, presented significant challenges at this tertiary care and research-oriented medical school. The new IGC course, Foundations of Patient Care, consists of on-campus lectures, small-group sessions, physical examination skills instruction, and a six-quarter preceptorship. As proposed, the school increased teaching of generalist skills and competencies and developed a large pool of primary care preceptors. There was no change in the number of graduates choosing primary care. The strong collaboration that resulted from the development of this new course served as a catalyst for major curricular reform now under way at this medical school.

Curriculum↗
PubMed2001

Placebo-controlled study of divalproex sodium for agitation in dementia.

The authors assessed the efficacy, tolerability, and safety of divalproex sodium for the treatment of agitation associated with dementia in a 6-week, randomized study of 56 nursing home patients with agitation and dementia treated with either placebo or individualized doses of divalproex sodium. Participants were blinded to treatment except for a physician-monitor and a pharmacist. When several covariates were taken into account, the drug/placebo difference in Brief Psychiatric Rating Scale Agitation scores became statistically significant (P=0.05). Sixty-eight percent of patients on divalproex were rated as showing reduced agitation on the Clinical Global Impression scale, vs. 52% on placebo (P=0.06 in the adjusted analysis). Side effects occurred in 68% of the divalproex group vs. 33% of the placebo group (P=0.03) and were generally rated as mild. This placebo-controlled study, despite some limitations, suggests possible short-term efficacy, tolerability, and safety of divalproex for agitation in dementia and supports further placebo-controlled studies.

Aged↗
PubMed1999

Withdrawal from controlled carbamazepine therapy followed by further carbamazepine treatment in patients with dementia.

BACKGROUND: The aim of this study was to assess the effects of withdrawal from placebo and carbamazepine administered for agitation associated with dementia and to assess safety, tolerability, and efficacy of subsequent ongoing carbamazepine therapy. METHOD: We previously reported the results of a 6-week, randomized, parallel-group study of placebo versus carbamazepine in 51 nursing home patients with dementia who were agitated; 47 subjects completed that study. This report first presents the results of withdrawal from that experimental treatment assessed by (blinded) observations 3 weeks later (N = 45 remaining). The primary outcome measure was the Brief Psychiatric Rating Scale. Secondary outcome measures addressed other aspects of behavior, cognition, function, safety, and tolerability. Patients were then treated with carbamazepine for an additional 6 weeks (N = 32 remaining) or 12 weeks (N = 25 remaining), with the same assessments performed. RESULTS: Patients who had previously shown behavioral improvement with carbamazepine therapy reverted to their baseline state after washout, whereas there was no change in the patients previously treated with placebo. There were no other significant effects of washout. During subsequent therapy with carbamazepine at a modal dose of 300 mg/day, there were 2 deaths and 4 other adverse events resulting in dropout. Neither of the deaths, and only 1 serious adverse experience, was judged to be related to carbamazepine. There were a variety of nonserious adverse experiences during the trial. Behavior ratings showed ongoing improvement in agitation and aggression, as well as in other aspects of psychopathology. CONCLUSION: The washout data provided independent confirmation of efficacy found in the prior placebo-controlled phase of this trial. Ongoing treatment was not associated with unexpected toxicity and was associated with improvement in measures of agitation and aggression that appeared to continue for up to 12 weeks. These findings confirm and extend results from earlier placebo-controlled studies.

Aggression↗
PubMed1998

Relationship between the regional and national incidence of transient ischaemic attack and stroke and performance of carotid endarterectomy.

OBJECTIVES: To examine the relationship between the incidence of transient ischaemic attack (TIA) and stroke on a national and regional level and the rate of carotid endarterectomy (CEA). SUBJECTS: Patients entered onto a national primary care computerised database with a new diagnostic code of stroke or TIA between 1992 and 1995. METHODS: Analysis of data from the primary care database and routine data sources. Main outcome measures were incidence of TIA and stroke and rates of CEA. RESULTS: The mean incidence per 100,000 of the population was 292 (TIA) and 356 (stroke) in England, 391 and 497 in Scotland and 349 and 448 in Northern Ireland. There was a variation in the incidence of TIA and stroke between both the regions and the regions and countries which was significant. There was a national increase in the rate of CEA between 1990 and 1995 which showed a marked variation across the regions. The inter-regional variation in rate of CEA correlated with the inter-regional difference in incidence of disease. CONCLUSIONS: The incidence of TIA and stroke may be higher than previously recognised, and varies significantly between the regions. This is generally associated with the variation in performance of CEA.

Cerebrovascular Disorders↗
PubMed1998

Efficacy and tolerability of carbamazepine for agitation and aggression in dementia.

OBJECTIVE: The efficacy, safety, and tolerability of carbamazepine in the treatment of agitation and aggression associated with dementia were assessed. METHOD: In a 6-week, randomized, multisite, parallel-group study of 51 nursing home patients with agitation and dementia, individualized doses of carbamazepine were compared with placebo. Except for a physician monitor and a pharmacist, all participants were blind to treatment. The primary outcome measures were the Brief Psychiatric Rating Scale (BPRS) and Clinical Global Impression (CGI) global improvement rating. Secondary measures included measures of behavior, aggression, cognition, functional status, staff time, safety, and tolerability. Intent-to-treat analysis was performed. RESULTS: The modal carbamazepine dose at 6 weeks was 300 mg/day, and a mean serum level of 5.3 micrograms/ml was achieved. The study was terminated after a planned interim analysis showed that carbamazepine provided more benefit than did placebo. Over 6 weeks the mean total BPRS score decreased 7.7 points for the carbamazepine group and 0.9 for the placebo group, and the weekly scores showed a gradual divergence between the two groups. CGI ratings showed global improvement in 77% of the patients taking carbamazepine and 21% of those taking placebo. Secondary analyses confirmed that the positive changes were due to decreased agitation and aggression. The drug was generally well tolerated, and no change in cognition or functional status occurred. The perception of staff time needed to manage agitation showed a decrease for carbamazepine but not placebo. CONCLUSIONS: This controlled study showed significant short-term efficacy of carbamazepine for agitation with generally good safety and tolerability.

Aged↗
PubMed1996

Hyperhomocysteinaemia is a risk factor for vein graft stenosis.

OBJECTIVES: Many infrainguinal vein graft failures are due to progressive vein graft stenosis (VGS) from intimal hyperplasia. Systemic factors have been implicated in the aetiology of intimal hyperplasia. Hyperhomocysteinaemia (HHCA) is established as an independent risk factor for coronary and peripheral arterial disease. The objective of this study was to examine the influence of HHCA and other serological factors upon the development of VGS. STUDY DESIGN: Thirty-eight patients who had undergone infrainguinal vein bypass were recruited to a case/control study from a graft surveillance program. Nineteen patients with documented VGS were matched against controls without stenosis for age, sex, length of time from surgery, diabetes, smoking history and preoperative symptom score. All patients were recalled for Duplex ultrasound scans, venesection and carbon monoxide estimation which were performed in a blinded fashion. RESULTS: Statistical analysis of all parameters revealed that plasma homocysteine was significantly elevated in patients with VGS (p < 0.3, Wilcoxon rank sum). CONCLUSIONS: These results suggest that HHCA is a previously unidentified risk factor for VGS. Patients with HHCA are susceptible to VGS and preoperative investigation would allow identification of patients at risk.

Adult↗
PubMed1994

Cement dermatitis in underground workers during construction of the Channel Tunnel.

The construction of the Channel Tunnel is one of the largest civil engineering projects ever undertaken. The British drive employed 5900 underground workers, and a number developed dermatitis during 1990/1991. As a result, the Translink Joint Venture (TLJV) Medical Centre set up a surveillance programme aiming to monitor and investigate the men working closely with cement as well as other groups of workers with skin problems. Men attended the Medical Centre voluntarily and were assessed, including history, examination and patch tests to a series of 15 test substances (from the European standard series) where indicated. A programme of education about the hazards of working with cement was instituted, including leaflets, videos, local newspaper articles and personal explanation by the Medical Centre staff. Between January 1990 and January 1992, 1138 men were seen at the Medical Centre regarding their skin and 332 were diagnosed as having occupational dermatitis, past or present. Patch tests were performed on 180 men from all trades. Of the 800 grouters, 466 (58 per cent) were assessed and 111 had a history of occupational dermatitis at some time. Many gave a history of a single episode of dermatitis during a particularly hot and wet phase of tunnelling. Patch tests performed on 86 grouters showed allergy to chromate in 56 (65 per cent). Of the 466 grouters assessed, 17 per cent had positive patch tests to chromate but men with no skin problems past or present were not patch tested. Cobalt allergy was often found with chromate allergy (50 out of 56).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Carbamazepine treatment of agitation in nursing home patients with dementia: a preliminary study.

OBJECTIVE: To determine the effects of carbamazepine versus placebo on ratings of behavior in agitated nursing home patients with dementia. DESIGN: Nonrandomized, placebo-controlled, crossover trial conducted in 25 patients in two nursing homes. INTERVENTION: Carbamazepine and placebo were administered during two 5-week periods separated by a 2-week washout. The carbamazepine dose was determined for each patient by a nonblinded physician who did not participate in ratings (modal dose 300 mg/day). MEASUREMENTS: The primary outcome measures were Brief Psychiatric Rating Scale scores and Clinical Global Impression of Change, rated by blind observers. Secondary measures of behavior, adversity, cognition, and functional status were also included. MAIN RESULTS: Median total Brief Psychiatric Rating Scale score decreased 7 points on carbamazepine versus 3 on placebo (P = 0.03). Sixteen subjects were rated as improved globally on carbamazepine versus four on placebo (P = 0.001). Secondary measures of behavior showed similar changes at significant or suggestive (P < 0.10) levels. One subject developed carbamazepine-induced tics, and one died with a pneumonia. There was minimal other adversity. CONCLUSION: This preliminary study suggests that carbamazepine in low doses can reduce agitated behaviors in some patients, with limited adversity resulting. Further research is required to confirm and extend this finding before it can be considered routine clinical practice.

Aged↗
PubMed1994

Tourette's syndrome in a special education population: a pilot study involving a single school district.

To determine whether children requiring special education represent a high-risk group for identifying Tourette's syndrome (TS), we performed direct examinations for the presence of tics in 35 special education and 35 regular classroom students from a single school district. Of the special education students, nine (26%) had definite or probable tics as compared with only two (6%) of the regular classroom students. About one-third of the students with tics currently meet diagnostic criteria for TS and probably more will do so in the future. About one-half of the subjects with tics have evidence of obsessive-compulsive behavior (OCB) or an attention-deficit hyperactivity disorder (ADHD). For three randomly selected students with definite tics, direct examinations of first-degree relatives revealed the presence of tics in all families. Subjects to the limitations of this pilot study, we conclude that TS and related tic disorders are commonly associated with the need for special education in this single school district. TS might also be an important contributor to school problems in the childhood population at large and may be a highly prevalent condition. In addition, we conclude that childhood tics are associated with OCB and ADHD, are genetically determined, and are part of the TS clinical spectrum.

Adolescent↗
PubMed1992

Micrographically controlled excision (Mohs' surgery) of basal cell carcinoma around the eye. Combined dermatological surgical clearance and oculoplastic surgical repair.

Periorbital infiltrative basal cell carcinomas are notoriously difficult to treat, particularly those around the medial canthus. Micrographically controlled excision with horizontal frozen sections (Mohs' surgery) allows for clearance of the tumour with minimal loss of normal tissue. Once the tumour has been completely removed, the defect can be repaired by the oculoplastic surgeon for the best functional and cosmetic result. This is the ideal treatment for tumours with a contiguous growth pattern that are liable to be seriously over or under treated by other modalities. The technique requires special training for both the operator and the Medical Laboratory Scientific Officer (MLSO). It is costly in time and manpower but in selected cases, where recurrent tumour is most dangerous and where tissue conservation is paramount, it may be invaluable. Close collaboration between dermatological and oculoplastic surgeons in such cases probably offers the patient the best treatment and outcome.

Basal Cell Carcinoma↗
PubMed1991

Long-term follow-up of lichen planus.

Several large series of patients with lichen planus were reported some 30 years ago but no recent large surveys have been published. In this study, detailed enquiry was made into the natural history of the disease in 214 patients followed up 8 to 12 years after presentation to the Dermatology Department. The key findings from this study showed that the mean age of onset of lichen planus in males was significantly lower than in females (40.3 years in males compared with 46.4 years in females, p less than 0.05). The main eruption of lichen planus cleared within one year in 68% of the patients but we found a higher recurrence rate than in previous series at 49%. Many patients suffered from persistent brown staining many years after the rash had cleared.

Female↗
PubMed1989

Hand venous hypertension complicating arterio-venous fistula construction for haemodialysis.

Vascular complications of arterio-venous fistula construction for haemodialysis are rare. We report a patient who developed the hand venous hypertension syndrome with ulceration, 2 years after successful construction of a side-to-side radio-cephalic fistula at the wrist. The surgical treatment was ligation of the distended vein immediately distal to the fistula in the hand, and fistula function was preserved. The ulceration healed within 2 weeks of surgery. This complication had not been seen previously in the Dialysis Unit at Cardiff Royal Infirmary where, over the past 20 years, 800 fistulae have been constructed.

Adult↗
PubMed1988

Cerebrospinal fluid correlates of depression in Huntington's disease.

Patients with Huntington's disease (HD) commonly have concomitant depressive disorders. Prompted by reports of elevated corticotropin releasing factor (CRF) and reduced 5-hydroxyindoleacetic acid (5-HIAA) concentrations in lumbar cerebrospinal fluid (CSF) of patients with major depression, these CSF constituents were examined in 56 nonmedicated patients who were in the early stages of HD. Elevated CRF concentrations were found in patients with HD in comparison with a control group of 21 subjects without neurologic illness. The CSF 5-HIAA concentrations in patients with HD did not differ from that in four normal volunteers. Patients with HD who had depressive disorders (major depression or dysthymia) did not differ from those without depression with respect to CSF 5-HIAA or CRF concentration. However, a positive correlation was observed between severity of major depression and CRF concentration. These findings suggest that the depression associated with HD may differ neurochemically from that seen in other major depressive disorders, and support the notion that clinically significant depressive symptoms reflect heterogeneous pathophysiologic conditions with different neurochemical correlates.

Adult↗