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J P Harris

Publications and source records attributed to J P Harris.

At least 19 recordsLinked to original sources
PubMed2006

Endovascular popliteal aneurysm repair: are the results comparable to open surgery?

INTRODUCTION: The aim of this study was to review our experience of popliteal aneurysms using endovascular techniques. METHODS: Thirty popliteal aneurysms in 25 patients were treated over an 11-year period. Median aneurysm diameter was 26 (16-48) mm. Five were symptomatic and 25 asymptomatic. Patients were treated with the Haemobahn/Viabahn stent-graft (26), Passager (two), Aneurx (one), and PTFE homemade device (one). Data were assessed using life table analysis, and expressed as cumulative patency rates and standard error (SE). RESULTS: Median follow-up was 24 (range 1-95) months. Primary patency was 92.9% (SE 4.5%), 84.7% (SE 6.8%), 80% (SE 8.2%), 74.5% (SE 9.4%) and 74.5% (11.3%) at 1, 6, 12, 24 and 36 months, respectively. Cumulative secondary patency was 96.5% (SE 3.3%), 88.7% (SE 6.0%), 88.7% (SE 8.6%), 83.2% (SE 8.0%) and 83.2% (SE 9.8%) at 1, 6, 12, 24 and 36 months, respectively. CONCLUSION: Endovascular treatment of popliteal aneurysms in this series achieved patency rates similar to open surgery. Aneurysm repair was performed without peroperative deaths and the risks associated with open surgery.

Aged↗
PubMed2005

Complications of aortic endografting.

Endovascular repair of abdominal aortic aneurysm has been shown to have a significantly lower perioperative mortality rate compared with open repair. It has been a blessing for patients at high risk who were previously denied treatment for their aortic aneurysms. It does, however, have a substantial need for re-intervention for complications. Many of these complications including endoleak, endotension, migration, post implant syndrome and conversion to open repair are unique to endovascular aneurysm repair. Others including injury to the iliac arteries, graft limb thromboses and structural failure of prostheses occur with greater frequency in endovascular repair compared with open repair. It is important, therefore, for vascular surgeons to be aware of these complications including their prevention and appropriate that patients are informed of their incidence. This review discusses the local and vascular complications of endovascular repair of abdominal aortic aneurysm with an emphasis on newer aspects.

Angioscopy↗
PubMed2003

Hemispace differences in the visual perception of size in left hemiParkinson's disease.

The visual perception of size in different regions of external space was studied in Parkinson's disease (PD). A group of patients with worse left-sided symptoms (LPD) was compared with a group with worse right-sided symptoms (RPD) and with a group of age-matched controls on judgements of the relative height or width of two rectangles presented in different regions of external space. The relevant dimension of one rectangle (the 'standard') was held constant, while that of the other (the 'variable') was varied in a method of constant stimuli. The point of subjective equality (PSE) of rectangle width or height was obtained by probit analysis as the mean of the resulting psychometric function. When the standard was in left space, the PSE of the LPD group occurred when the variable was smaller, and when the standard was in right space, when the variable was larger. Similarly, when the standard rectangle was presented in upper space, and the variable in lower space, the PSE occurred when the variable was smaller, an effect which was similar in both left and right spaces. In all these experiments, the PSEs for both the controls and the RPD group did not differ significantly, and were close to a physical match, and the slopes of the psychometric functions were steeper in the controls than the patients, though not significantly so. The data suggest that objects appear smaller in the left and upper visual spaces in LPD, probably because of right hemisphere impairment.

Aged↗
PubMed2003

Endovascular repair of abdominal aortic aneurysm in the multifocal atherosclerotic patient.

One of the major problems of treating aortic aneurysms has been the multifocal nature of atherosclerotic disease. Co-existing cardiovascular disease in the majority of patients together with chronic obstructive airways disease, renal impairment and hostile abdomen in some, has resulted in 1/3 of patients presenting with aortic aneurysms being regarded as high risk and unfit for open repair. Endovascular repair of aortic aneurysm therefore has much to recommend it since it avoids the need for laparatomy, cross clamping of the aorta and the obligatory blood loss associated with opening of the sac. Between May 1992 and March 2003 we have used the endovascular method to repair abdominal aortic aneurysms (AAA) in 583 patients. Successful repair was achieved in 563 patients (96%). The remaining 20 patients required primary conversion to open repair at the original operation. The 30-day perioperative mortality rate was 13 of 583 (2.2%). In this paper we summarise a number of studies that we have undertaken, comparing endovascular with alternative treatment methods and comparing various types of endovascular prostheses. In addition we report the long-term outcome of endovascular AAA repair as it relates to morphological changes in the proximal neck out to 9 years from operation. We conclude that despite the continuing small incidence of device failure, endovascular is the preferred method of AAA repair in the multifocal atherosclerotic patient. This view is based on the low perioperative mortality, superior survival compared with open repair and our experience of long-term stability in the proximal neck in the majority of patients.

Aged↗
PubMed2003

Overcounting of black Africans in the UK: the problem of undetected record duplication.

Difficulties in recording unfamiliar African names, leading to inconsistent reporting of 'surname' code of the same individual, has raised concern that there is overcounting of newly diagnosed HIV-positive black Africans in the UK. Date of birth was used as a proxy indicator for duplication of entries of black Africans in the national HIV/AIDS patient database. Significantly more black Africans (59%) than whites (56%) share the same date of birth (p = 0.0023), and among black Africans certain birthdays occur at a very high frequency. Those born in Africa may not know their exact date of birth and so may be choosing, or have chosen for them, memorable or auspicious dates instead. After removal of individuals with birthdays consisting of the same number day and month, the evidence of disproportionate duplication of black Africans' dates of birth was weaker (p = 0.0129). Although this investigation provided evidence of selective failure to detect duplicated reports of the same individual among reports of HIV-positive black Africans, in practical terms, the relatively small proportion (2.4%) of remaining excess duplicates is equivalent to 141 black African individuals on the database, and would not impact on the overall picture of the HIV epidemic in the UK.

Humans↗
PubMed2002

Dopamine and the representation of the upper visual field: evidence from vertical bisection errors in unilateral Parkinson's disease.

It has been suggested that dopamine is an important neurotransmitter in the brain mechanisms which represent the upper visual field. This idea was tested with a vertical line bisection task in unilateral Parkinson's disease. Stimuli of a range of lengths were presented on a large screen in three positions (left, centre and right) and at two viewing distances (0.6 and 1.5m). The patients, who were compared with a group of normal age-matched controls, comprised 16 sufferers from predominantly unilateral disease, 8 with more severe left-sided symptoms (LPD) and 8 with more severe right-sided symptoms (RPD). The LPD group consistently set the bisecting cursor below the midpoint of the stimulus lines, and their bisection error became larger as the length of the line increased. In contrast, the controls set the cursor above the midpoint of the line, an error which also increased with line length. The settings of the RPD group were similar to those of the controls. The results suggest altitudinal neglect in left unilateral PD, and support the hypothesis of dopaminergic involvement in the coding of upper visual space, with the proviso that the perceptual component of this involves the right hemisphere in humans.

Aged↗
PubMed2002

On temporal hyperacuity in the human visual system.

The spatial grain of the human visual system has always been a central topic for visual sciences, and the optical and physiological basis of perceptual limitations are well described. In particular, we have thorough accounts of spatial hyperacuity, which refers to a precision in the spatial localisation of stimulus contours that is better than the photoreceptor grain that determines spatial resolution. However, although the temporal resolution of the human visual system is comparably well described, we have almost no direct knowledge about the precision of localising visual stimuli in time in the absence of correlated spatial cues. The present study addresses this question by comparing directly the temporal resolution of human observers with their temporal acuity as measured in a temporal bisection task. Despite some improvement with practice, temporal acuity in this task does not fall below 20-30 ms in the best case, which is similar to the temporal resolution limit, and performance does not improve for comparison tasks with multiple stimulus presentations. The absence of visual hyperacuity for purely temporal modulations as tested here contrasts with processing limitations for other types of visual information in comparable tasks, and with other sensory modalities, in particular to those of the auditory system. Such differences can be interpreted in the context of the ecological requirements for organising behaviour, and the functional design of nervous systems.

Adult↗
PubMed2002

Evidence for spatio-temporal selectivity in attentional modulation of the motion aftereffect.

An ignored region of the visual field might be monitored by an intermittent full visual analysis or by a more continuous but restricted analysis. We investigated which type of process is more likely in early vision by studying the effects of diverting attention on adaptation to a range of spatial (0.5, 2, 4. and 6 c/deg) and temporal (1.5 and 10 Hz) frequencies. During adaptation, subjects either fixated an unchanging digit (normal attention). or named the sequence of changing digits which formed the fixation point (diverted). The test field was always a static version of the adapting field, and the strength of adaptation was measured through the velocity and duration of subsequent Motion Aftereffects (MAEs). When attention during adaptation was normal MAE durations rose with spatial frequency for the 1.5 Hz stimuli, and declined with spatial frequency for the 10 Hz stimuli. When attention was diverted from the 10 Hz stimuli, MAE durations and velocities fell by a similar amount at all spatial frequencies. However, for the 1.5 Hz stimuli, the effects of diversion were very small at 0.5 c/deg, and rose progressively with spatial frequency, so that MAE reductions were largest at 6 c/deg. It appears that diversion hardly affects the encoding of coarse, slow stimuli, but attenuates the encoding of finer and/or faster stimuli. This is consistent with the idea that during diversion the visual system monitors the scene continuously, but over a restricted range of spatial and temporal scales.

Adaptation, Ocular↗
PubMed2001

Disruption of estimation of body-scaled aperture width in Hemiparkinson's disease.

A group of patients with left-sided symptoms of Parkinson's disease (LPD) was compared with a group of patients with right-sided symptoms (RPD) and with a group of healthy age-matched controls on body-scaled judgements of aperture width. Participants judged whether or not they would fit through a life-sized schematic doorway shown on a large screen. A staircase technique was used to find the door width for which 50% of the judgements were positive. The ratio between this measure and the width of the participant's body at the shoulders (the aperture to shoulder - A/S ratio) was calculated. The A/S ratio was approximately 1.5 in the LPD group, approximately 0.9 in the RPD group, and approximately 1.1 in the control group, suggesting that the visual representation of the doorway (or that of its relationship to perceived body-size) is compressed in LPD (and perhaps expanded in RPD). The A/S ratios were invariant with viewing distance (0.6 or 1.5 m), the contrast polarity of the display (white on dark, or vice versa) and the doorway surround (blank, or vertical or horizontal stripes). The findings are discussed with reference to the neural representation of external space and of the body, and to the motor problems of Parkinson's disease.

Aged↗
PubMed2001

Biosynthesis of diaporthin and orthosporin by Aspergillus ochraceus.

Diaporthin and orthosporin were characterised from the fungus Aspergillus ochraceus D2306. Diaporthin was identified by high-resolution electron impact mass spectrometry and 1H and 13C NMR spectroscopy, from which new spectroscopic assignments were made. Orthosporin was also identified by mass spectrometry and both fungal metabolites are reported for the first time as co-metabolites and also as products of A. ochraceus. The methylation inhibitor ethionine affected production of both diaporthin and orthosporin in spite of no obvious methylation step in the biosynthesis of orthosporin, implying that extracellular orthosporin may arise by de-O-methylation of diaporthin. The biosynthetic origin of diaporthin was demonstrated by incorporation of [1-14C]acetate and [methyl-14C]methionine administered in early idiophase.

Aspergillus↗
PubMed2001

Biosynthesis of ochratoxins by Aspergillus ochraceus.

Shaken liquid fermentation of an isolate of Aspergillus ochraceus showed growth-associated production of ochratoxins A and B, followed by production of a related polyketide diaporthin. Later, between 150 and 250 h, mellein accumulated transitorily. In contrast, shaken solid substrate (shredded wheat) fermentation over 14 days produced mainly ochratoxins A and B (ratio ca. 5:1) in very high yield (up to 10 mg/g). In these systems experiments with 14C-labelled precursors and putative intermediates revealed temporal separation of early and late stages of the ochratoxin biosynthetic pathway, but did not support an intermediary role for mellein. The pentaketide intermediate ochratoxin beta was biotransformed very efficiently into both ochratoxins A and B, 14 and 19%, respectively. The already chlorinated ochratoxin alpha was only biotransformed significantly (4.85%) into ochratoxin A, indicating that chlorination is mainly a penultimate biosynthetic step in the biosynthesis of ochratoxin A. This was supported by poor (1.5%) conversion of radiolabelled ochratoxin B into ochratoxin A. Experiments implied that some ochratoxin B may arise by dechlorination of ochratoxin A.

Aspergillus ochraceus↗
PubMed2001

Evidence from a line bisection task for visuospatial neglect in left hemiparkinson's disease.

The perception of extrapersonal space in Parkinson's disease was examined with two line bisection tasks. One was a conventional pencil and paper test, the line bisection section of the Behavioural Inattention Test. In the other, the stimuli were displayed on a large (2x2.4 m) screen and varied in length (48-480 mm) and also in location on the screen (left, centre and right). They were presented at two viewing distances (0.6 and 1.5 m). Subjects remotely adjusted the position of a cursor until it appeared to bisect the stimulus line, using two push-buttons, one in each hand. The PD participants (n=18) had a marked asymmetry of motor symptoms. They were divided into two groups, those with predominantly left-sided motor symptoms (LPD, n=9), and those with predominantly right-sided motor symptoms (RPD, n=9). The control group (n=9) were all right-handed. No significant differences between the groups were found on the BIT bisection task. In contrast, when the stimuli were presented on the screen, LPD subjects showed a significant rightward bias in their settings of the cursor, particularly for lines on the left and centre of the screen, which was greater, the longer the stimulus line. The RPD group bisected lines slightly to the left, in common with the control group (pseudo-neglect). In a second experiment, Parkinsonian subjects repeated this task, but with the buttons reversed between the hands, so that the cursor was moved to the left by the right hand, and vice versa, but the pattern of results was the same as in the first experiment. The data suggest a small but reliable neglect in left hemiparkinson's disease, which is contralateral to the non-dominant (and probably worse affected) hemisphere. The dissociation between the response and the bisection error suggests a visuospatial impairment in LPD.

Aged↗
PubMed2001

Endoluminal repair of abdominal aortic aneurysms - state of the art.

This paper considers the historical aspects of endovascular aneursym repair; the major findings of our Departments experience over an 812-year period and reviews recent developments in endovascular prostheses. Analysis of 400 patients undergoing primary repair of abdominal aortic aneurysm between 1992 and 2000 revealed a perioperative mortality rate of 2.7% and primary conversion rate of 5%. With sequential studies it was shown that the outcome was better with bifurcated/aorto uni iliac grafts than tube grafts; better with second generation prostheses than first generation protheses and that survival in consecutive patients treated concurrently by open repair and endoluminal repair was superior in the endoluminal group. Endoluminal AAA repair is at a critical point of its development. It is unquestioned that it can dramatically reduce the need for intensive care and length of hospital stay and more recently it has been reported that survival is improved compared with open repair. The need for lifetime surveillance, the probability of graft failure and need for re-intervention, however, negate some of the advantages. The small incidence of unpredictable rupture following endoluminal AAA repair is a timely reminder of the need for continued careful follow-up.

Aortic Aneurysm, Abdominal↗
PubMed2001

Maternal obesity and pregnancy outcome: a study of 287,213 pregnancies in London.

OBJECTIVE: To examine the maternal and foetal risks of adverse pregnancy outcome in relation to maternal obesity, expressed as body mass index (BMI, kg/m(2)) in a large unselected geographical population. DESIGN: Retrospective analysis of data from a validated maternity database system which includes all but one of the maternity units in the North West Thames Region. A comparison of pregnancy outcomes was made on the basis of maternal BMI at booking. SUBJECTS: A total of 287,213 completed singleton pregnancies were studied including 176,923 (61.6%) normal weight (BMI 20--24.9), 79 014 (27.5%) moderately obese (BMI 25--29.9) and 31,276 (10.9%) very obese (BMI> or =30) women. MEASUREMENTS: Ante-natal complications, intervention in labour, maternal morbidity and neonatal outcome were examined and data presented as raw frequencies and adjusted odds ratios with 99% confidence intervals following logistic regression analysis to account for confounding variables. RESULTS: Compared to women with normal BMI, the following outcomes were significantly more common in obese pregnant women (odds ratio (99% confidence interval) for BMI 25--30 and BMI> or =30 respectively): gestational diabetes mellitus (1.68 (1.53--1.84), 3.6 (3.25--3.98)); proteinuric pre-eclampsia (1.44 (1.28--1.62), 2.14 (1.85--2.47)); induction of labour (2.14 (1.85--2.47), 1.70 (1.64--1.76)); delivery by emergency caesarian section (1.30 (1.25--1.34), 1.83 (1.74--1.93)); postpartum haemorrhage (1.16 (1.12--1.21), 1.39 (1.32--1.46)); genital tract infection (1.24 (1.09--1.41), 1.30 (1.07--1.56)); urinary tract infection (1.17 (1.04-1.33), 1.39 (1.18--1.63)); wound infection (1.27 (1.09--1.48), 2.24 (1.91--2.64)); birthweight above the 90th centile (1.57 (1.50--1.64), 2.36 (2.23--2.50)), and intrauterine death (1.10 (0.94--1.28), 1.40 (1.14--1.71)). However, delivery before 32 weeks' gestation (0.73 (0.65--0.82), 0.81 (0.69--0.95)) and breastfeeding at discharge (0.86 (0.84--0.88), 0.58 (0.56--0.60)) were significantly less likely in the overweight groups. In all cases, increasing maternal BMI was associated with increased magnitude of risk. CONCLUSION: Maternal obesity carries significant risks for the mother and foetus. The risk increases with the degree of obesity and persists after accounting for other confounding demographic factors. The basis of many of the complications is likely to be related to the altered metabolic state associated with morbid obesity.

Adult↗
PubMed2001

Why do some patients with > 80% stenosis of the internal carotid artery not undergo surgery? A retrospective review.

BACKGROUND: Carotid endarterectomy is known to benefit both symptomatic and asymptomatic patients with high-grade internal carotid artery stenosis. Duplex scanning is the 'gold standard' for non-invasive preoperative investigation of carotid artery stenosis. The aim of the present study was to analyse the indications for duplex scanning and to identify other factors that influenced the management of patients with high-grade stenosis who did not undergo carotid endarterectomy. METHODS: A total of 271 patients was observed to have > 80% stenosis of the internal carotid artery on duplex scanning during the period of review. Of these patients, 85 did not undergo carotid endarterectomy. The vascular laboratory database and hospital records of these patients were retrospectively reviewed. RESULTS: The indications for requesting a carotid duplex scan in the 85 patients were transient ischaemic attack (22%), stroke (25%), symptomatic bruit (7%), asymptomatic bruit (12%), and stroke and symptomatic bruit combined (7%). Falls and preoperative carotid assessment prior to coronary surgery were the commonest indications in the remaining patients. The main risk factors were cardiac (68%), hypertension (60%), respiratory (21%), diabetes (25%), peripheral vascular disease (19%), neoplasm (16%) and renal disease (16%). Twenty-five per cent of the patients were over 80 years of age. CONCLUSION: In the present study risk factors associated with increased perioperative morbidity and mortality were the commonest explanation for patients with high-grade stenosis of the internal carotid artery not undergoing surgery. These patients would generally not meet the inclusion criteria for the major carotid endarterectomy trials.

Age Factors↗
PubMed2001

Improved survival after endoluminal repair with second-generation prostheses compared with open repair in the treatment of abdominal aortic aneurysms: a 5-year concurrent comparison using life table method.

PURPOSE: The aim of this study was to compare the outcome of consecutive patients with abdominal aortic aneurysm (AAA) treated concurrently by means of open repair (OR) and endoluminal repair (ER) with second-generation prostheses by the same surgeons during a defined interval. METHODS: Between May 1995 and December 1998 second-generation (low profile, fully supported, modular) endoprostheses were implanted in 148 patients. These patients, together with 135 patients treated concurrently with OR during the same period, comprised the study group of 283 patients. Patient selection was based on aneurysm morphology. Those patients who were anatomically suitable for ER were treated with this method. The ER and OR groups were similar with regard to age, sex, and size of AAA. The ER group contained high-risk patients considered unfit for OR (n = 46), and the OR group contained high-risk patients who were anatomically unsuitable for ER (n = 19). Outcome criteria in both groups were survival and successful aneurysm repair. Success in the ER group was defined as exclusion of the aneurysm sac and stability or reduction in AAA maximum transverse diameter. Persistent endoleaks were classified as failures, regardless of whether they were subsequently corrected with secondary endovascular intervention. Data were analyzed with the life table method. The minimum period of follow-up for all patients was 18 months. RESULTS: The perioperative mortality rate was 5.9% in the OR group and 2.7% in the ER group (not significant). There was a statistically significant difference between the survival curves of the two groups in favor of the ER group when analyzed with the log-rank test (P =.004). The Kaplan-Meier curve for graft failure for the ER group revealed a 3-year graft success probability of 82%. Survival probability with successful repair in the OR group at 3 years was 85%. CONCLUSIONS: A concurrent comparison of ER with second-generation prostheses versus OR demonstrated a significant difference in survival in favor of the ER group. The probability of survival with successful repair at 3 years was similar in both groups.

Aged↗