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Biomedical subjects

I Wright

Publications and source records attributed to I Wright.

At least 19 recordsLinked to original sources
PubMed2003

Integrated approach to off-pump coronary artery bypass surgery.

BACKGROUND: The Off-Pump Coronary Artery Bypass (OPCAB) technique is becoming more popular in many cardiac units throughout the world. This relatively new technique has prompted surgeons and anaesthetists to review and modify the routine approach to Coronary Artery Bypass Surgery (CABG). In this study we reviewed and analysed the outcome of an integrated anaesthetic and surgical peri-operative approach that allowed routine use of OPCAB and avoided the use of cardiopulmonary bypass (CPB). METHODS: We reviewed and analysed the data on the first consecutive 285 patients who were operated on using the OPCAB technique. These represent our initial experience with applying the OPCAB technique non-selectively for all patients over a period of 16 months. RESULTS: All patients had at least 2-vessel disease. 807 grafts were performed (mean 2.8 per patient) of which 647 (80%) were arterial (mean 2.3 per patient). 179 (63%) patients underwent total arterial revascularization. Eight patients required cardiopulmonary bypass; all other operations were completed off-pump. Complications--mortality 3 (1%); renal failure 24 (8%); stroke 3 (1%) and atrial fibrillation 60 (21%). CONCLUSION: This retrospective analysis shows that provided a combined and integrated anaesthetic and surgical approach is used, beating heart technique for CABG can be safely offered to all patients with a good outcome.

Blood Pressure↗
PubMed2000

Is there carotid artery aneurysm formation following saphenous vein patch endarterectomy?

The use of saphenous vein patching following carotid endarterectomy is reported to produce aneurysmal dilatation with the risk of thrombosis and possible rupture. The authors have studied patients who have had saphenous vein patch angioplasty following carotid endarterectomy to assess whether there is any progressive arterial dilatation. Thirty-five patients who had undergone saphenous vein patch carotid endarterectomy were age- and sex-matched with 31 subjects that had direct closure endarterectomy. All participants underwent carotid duplex scanning. The external diameters of the mid common carotid artery, the bulb and the proximal internal carotid artery were measured bilaterally. The diameters of the endarterectomized carotid were compared with the contralateral side using a paired t-test. Using an unpaired t-test, the saphenous vein angioplasty group was compared with the directly closed group. A graph was plotted of the ratio of internal carotid artery diameter of the saphenous vein angioplasty group (endarterectomized artery to the contralateral artery) against the length of follow-up, and the Pearson correlation coefficient was calculated. When the saphenous vein angioplasty group was compared with the directly closed group there was a significant difference between the carotid bulb (11.6 versus 9.7mm, P < 0.001) and internal carotid artery diameters (9.0 versus 7.0mm, P < 0.001). Longitudinal analysis of the saphenous vein angioplasty group showed that the increased diameter of the endarterectomized internal carotid artery progressed with time after surgery (r = 0.51, P < 0.005, and r = 0.56, P < 0.001). Vein patching increases the diameter of the internal carotid artery, and this may further increase with time possibly predisposing to aneurysm formation. Further longitudinal studies of paired data are required.

Adult↗
PubMed2000

Self-reported health in relation to medical health and gender-specific problems in women.

Self-reported health was studied in relation to physiological measures, gender-specific problems, and clinical evaluation in 61 middle-aged women employed in a male-dominated industry. Using self-reported somatic health as the dependent variable, 50% of the variability was explained by the dimension workplace culture and the ratio low-density lipoprotein/high-density lipoprotein. Some women who reported good health were diagnosed with distress but showed no ill-health factors. However, they reported experiences of gender-specific problems more often than the women who were diagnosed as being healthy. We concluded that self-report scales seem not to be enough to identify people who look healthy on standard health scales but who use psychological defenses. Differentiating methods such as gender-specific questions, physiological ratio-measures, and clinical judgment seem to be important for distinguishing genuine from illusory mental or physical health.

Adult↗
PubMed2000

A strategy for recruiting and retaining health information management professionals.

In the summer of 1998, the University Health Network (UHN) faced an acute personnel situation in which an exodus of skilled resources was taking place. The turnover of information management staff was increasing dramatically, and despite best efforts to recruit new employees, the vacancy rate remained at an unsustainable level. This case study reviews both the short- and long-term strategies that were employed to address these issues and to establish UHN as an employer of choice in health information management. Material in this article is based in part on papers presented at HIMSS 2000 and INFOCUS 2000 (Cameron, Claiter and Murphy 2000).

Career Mobility↗
PubMed1999

A weak pulsed magnetic field affects adenine nucleotide oscillations, and related parameters in aggregating Dictyostelium discoideum amoebae.

A model eukaryotic cell system was used to explore the effect of a weak pulsed magnetic field (PMF) on time-varying physiological parameters. Dictyostelium discoideum cells (V12 strain) were exposed to a pulsed magnetic field (PMF) of flux density 0.4 mT, generated via air-cored coils in trains of 2 ms pulses gated at 20 ms. This signal is similar to those used to treat non-uniting fractures. Samples were taken over periods of 20 min from harvested suspensions of amoebae during early aggregation phase, extracted and derivatised for HPLC fluorescent assay of adenine nucleotides. Analysis of variance showed a significant athermal damping effect (P < 0.002, n = 22) of the PMF on natural adenine nucleotide oscillations and some consistent changes in phase relationships. The technique of nonlinear dielectric spectroscopy (NLDS) revealed a distinctive effect of PMF, caffeine and EGTA in modulating the cellular harmonic response to an applied weak signal. Light scattering studies also showed altered frequency response of cells to PMF, EGTA and caffeine. PMF caused a significant reduction of caffeine induced cell contraction (P < 0.0006, n = 19 by paired t-test) as shown by Malvern particle size analyser, suggesting that intracellular calcium may be involved in mediating the effect of the PMF.

Adenine Nucleotides↗
PubMed1999

A vascular basis for repetitive strain injury.

OBJECTIVE: The blanket term 'repetitive strain injury' (RSI) covers a wide variety of work-related clinical syndromes, most of which are localized lesions. However, some patients complain of diffuse forearm pain, a clinically distinct form of RSI, the aetiology of which is unknown. METHODS: Using Doppler ultrasound, we measured the vascular responses to muscular work in the radial artery in 13 patients with bilateral diffuse forearm pain, seven with unilateral diffuse pain and 19 controls with localized arm pain. RESULTS: We found that in diffuse forearm pain the radial artery is relatively constricted compared to the controls and fails to vasodilate with exercise, which suggests that diffuse forearm pain may be due to physiological claudication of the working forearm muscle. CONCLUSION: A possible explanation is inhibition of local endothelial nitric oxide function, and this may be an unusual secondary, but self-perpetuating, pain condition which can follow other more specific, but chronic, arm pain syndromes in susceptible individuals.

Adolescent↗
PubMed1998

Innovative informatics education: aligning theory and practice through strategic partnership.

The University of Victoria School of Health Information Science (HINF) and The Toronto Hospital (TTH) have formed a strategic partnership to align current information management theory with practical experience. The fourth year undergraduate course in Information Management and Technology was redesigned to include a joint research project with TTH. Staff from TTH were paired with groups of 2-3 students to explore current information management issues. Technology such as electronic mail and conference calls enabled timely communication. Final results were presented via video conference at the end of the term and jointly graded by the professor and hospital staff. Over the three years, a variety of projects have been undertaken and the approach has been refined. Each year offered new insight to both students and staff. Findings include several key success factors: senior level support, early planning, timely communication, access to technology, and opportunity for staff and student feedback. This partnership offers strategic advantages to both organizations in innovation, mutual learning, recruiting, and partnership. Next steps include expansion of the project to a regional model and seminars on current information management topics for TTH staff.

Canada↗
PubMed1997

A functional magnetic resonance imaging study of episodic memory.

We have used whole brain fMRI and canonical variate analysis to investigate the anatomical location of brain activity subserving episodic memory encoding and recognition. Recognition of previously presented words did not specifically activate right prefrontal areas although right-sided activations were seen during transitions between the target and reference phases of the paradigm. Encoding was associated with left sided prefrontal activation, but this was within Broca's area rather than dorsolateral prefrontal cortex. The temporal resolution of fMRI, combined with analysis of the apparent functional connectivity of activations observed, revealed activity within complex networks each functionally specialized for the demands of particular aspects of a cognitive task.

Adult↗
PubMed1997

Developmental insanity or dementia praecox: was the wrong concept adopted?

Over a century ago, the Scottish psychiatrist Thomas Clouston proposed the idea of a developmental or adolescent insanity. He characterised the condition as having a male predominance and a poor outcome, and noted the frequency of a family history and of minor anomalies of the palate; he considered it a disorder of cortical development and the onset of psychotic symptoms due to maturation during adolescence "of certain parts of the brain which had lain dormant before". Clouston's idea was subsequently eclipsed by the broader dementia-praecox espoused by Kraepelin and Bleuler, but recent epidemiological, neuroimaging, and neuropathological research supports the existence, within the schizophrenia syndrome of a group of patients with a severe, early onset, developmental psychosis. This disorder, re-christened as neurodevelopmental schizophrenia, is associated with childhood language and speech difficulties which render subjects more likely to later misinterpret their own inner speech as external voices; like all developmental disorders of language, it is commoner in males. Predisposing factors include the inheritance of abnormal cerebral asymmetry, and early environmental hazards of brain development such as prenatal exposure to maternal viral infection and perinatal complications.

Adolescent↗
PubMed1996

A direct demonstration of functional specialization within motion-related visual and auditory cortex of the human brain.

BACKGROUND: Physiological studies of the macaque brain have shown that there is a large expanse of visual cortex, the V5 complex, which is specialized for visual motion, and that several areas within V5 are specialized for different kinds of visual motion. In continuing work on motion-related visual cortex, we wished to chart the specialized visual motion areas in the human brain and to determine their anatomical relationship. Human subjects viewed different motion displays, and the cortical location of the increased activity produced by each stimulus was recorded. The technique of functional magnetic resonance imaging (fMRI) was used, in order to image the same subjects repeatedly. RESULTS: We found that each of the three motion stimuli activated specific parts of the V5 complex. These sites of activation overlap with V5 and, to a smaller extent, with each other. Unexpectedly, the three motion stimuli also activated neighbouring, but nonoverlapping, regions of auditory cortex that are normally activated by the perception of speech. CONCLUSIONS: The three sites of activation produced by the visual motion stimuli occupy adjacent territories within the V5 complex. Components of the V5 complex are specifically connected to regions within auditory cortex.

Auditory Cortex↗
PubMed1996

Auditory hallucinations inhibit exogenous activation of auditory association cortex.

Percepts unaccompanied by a veridical stimulus, such as hallucinations, provide an opportunity for mapping the neural correlates of conscious perception. Functional magnetic resonance imaging (fMRI) can reveal localized changes in blood oxygenation in response to actual as well as imagined sensory stimulation. The safe repeatability of fMRI enabled us to study a patient with schizophrenia while he was experiencing auditory hallucinations and when hallucination-free (with supporting data from a second case). Cortical activation was measured in response to periodic exogenous auditory and visual stimulations using time series regression analysis. Functional brain images were obtained in each hallucination condition both while the patient was on and off antipsychotic drugs. The response of the temporal cortex to exogenous auditory stimulation (speech) was markedly reduced when the patient was experiencing hallucinating voices addressing him, regardless of medication. Visual cortical activation (to flashing lights) remained normal over four scans. From the results of this study and previous work on visual hallucinations we conclude that hallucinations coincide with maximal activation of the sensory and association cortex, specific to the modality of the experience.

Acoustic Stimulation↗
PubMed1996

Insoluble complex formation between LDL and arterial proteoglycans in relation to serum lipid levels and effects of lipid lowering drugs.

Lipoprotein deposition and increased intimal proteoglycans are characteristics of the atherosclerotic lesion in which low density lipoproteins (LDL) bind with high affinity to proteoglycans. The affinity of LDL to proteoglycans is dependent on its structural and compositional characteristics. This study investigated the relationship between serum lipid levels and LDL-proteoglycan reactivity. We also analyzed how lipid-lowering drugs affect this interaction. Patients with moderate hypercholesterolemia (n = 147) were randomized to pravastatin 40 mg o.d., gemfibrozil 600 mg b.i.d., gemfibrozil+pravastatin (same doses) or placebo. LDL reactivity with proteoglycans was analyzed by precipitation of serum with isolated human arterial proteoglycans. Reactivity was determined as amount of precipitated cholesterol or apolipoprotein (apo) B. Under the conditions used, 53% of the LDL cholesterol and 29% of serum apo B were precipitated. There were strong correlations between precipitated LDL and serum levels of cholesterol, LDL or apo B. No correlations were found with serum lipoprotein(a) (Lp(a)) levels. During pravastatin treatment, cholesterol was reduced by 26.5% and triglycerides by 9.8%. During gemfibrozil treatment corresponding figures were 16.8 and 40.2, and for the combined treatment, 27.5% and 34.2%. On all treatments, the reactivity of LDL with proteoglycan was reduced. The effects were significantly larger in the groups treated with gemfibrozil. This was correlated with the increase in high density lipoprotein (HDL) during gemfibrozil treatment. In hypercholesterolemia, the reactivity of LDL with proteoglycan is increased; treatment with lipid-lowering drugs lowers this reactivity, the effect being greatest for gemfibrozil. This might be due to conformational changes of LDL during treatment with gemfibrozil, unrelated to its lipid lowering effect. Since binding of LDL to proteoglycans is central in atherogenesis, this may be of importance for the role of gemfibrozil as an antiatherogenic drug.

Adult↗
PubMed1996

Duplication of the superficial femoral vein: recognition with duplex ultrasonography.

Duplication of the superficial femoral vein (SFV) is a normal variant seen in 20% of contrast phlebograms. Failure to identify thrombus in one limb of a SFV may lead to inappropriate management and subsequent complications. Colour Doppler imaging (CDI) is now the imaging technique of choice in the diagnosis of a deep vein thrombosis (DVT). The purpose of this study was to identify the prevalence of duplication of the SFV at CDI and to compare this with the known prevalence at contrast phlebography. CDI was performed on 58 healthy volunteers (116 limbs examined). Duplication of the SFV was present in 29 examinations (25%). Ultrasonic measurement of the diameter of the SFV was performed in all patients. In the presence of duplication a significant reduction in the diameter of both limbs of the SFV was noted when compared with an unduplicated vessel. The prevalence of duplication of the SFV at CDI is comparable to that at contrast phlebography. Recognition of this variant may help reduce false negative CDI examinations.

Adult↗
PubMed1996

Comparison of clinical follow-up and duplex surveillance of infrainguinal vein bypasses.

The evidence in support of surveillance has been principally based on the favourable primary-assisted patency of stenosed grafts following revision (60-80% at 5 years) compared with the poor secondary patency of revised occluded grafts (20-40% at 5 years). Both the capital cost and workload generated by surveillance are considerable. More information is needed on the benefits of surveillance compared with clinical follow-up. A retrospective comparison of 50 vein grafts (44 reversed, six in situ) undergoing colour-coded duplex surveillance and 50 vein grafts (46 reversed, four in situ) under clinical follow-up, with duplex scans obtained only when clinically indicated, has been performed. Four (8%) stenoses of > or = 50% were identified in the surveillance group. One 50% proximal anastomotic stenosis failed to progress on sequential scans. Three stenoses were treated (one mid graft, two popliteal) by vein patch angioplasty (two cases) and transluminal angioplasty (one case). Both groups were followed-up for 12 months. Secondary patency at 12 months (88% surveillance; 80% clinical follow-up) was not significantly different (P = 0.3). Similarly, limb salvage at 12 months (94% surveillance; 88% controls) was not significantly different (P = 0.4). A large randomized prospective study comparing duplex surveillance and clinical follow-up is warranted.

Adult↗