Biomedical subjects
Publications and source records attributed to R A Baker.
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Electronic data collection during cardiac surgery creates an enormous data source that has many potential applications. After the introduction of the Stockert Data Management System (DMS; Munich, Germany) to our perfusion practice, we recognized that the data could be used for the purpose of quality control (QC). Our aim was to create an automated technique of data analysis and feedback for cardiopulmonary bypass (CPB) procedures. Using visual basic programming, we created a process by which data from the DMS is analyzed and processed in a Microsoft Access database after a CPB procedure. The processing is designed to transfer the collected data to a research database and create a number of CPB quality indicator (QI) parameters, such as mean arterial pressure being less than 40 mmHg for more than 5 minutes or a venous saturation of less than 60% for more than 5 minutes. In the event of QI parameter detection, a QC report is generated and e-mailed to the senior perfusionist and the perfusionist performing the procedure. The introduction of electronic data collection and subsequent development of electronic data processing techniques has enabled us to transfer the data into a readily accessible database and create a data set of perfusion variables and quality indicators for CPB procedures. This data set may be used for immediate automated QC feedback after CPB procedures and direction of performance improvement initiatives through retrospective or prospective data analysis as part of a continuous quality improvement process.
The past few years have seen an increasing emphasis upon the role of the dental team in smoking cessation. The recent advances in knowledge of the level and role of tobacco use in patients with mental and behavioural disorders, the biological factors involved and the influences of tobacco on psychiatric medication metabolism and side effects has not been reflected in dental postgraduate education. Perhaps it is time for an evidence based improvement in care standards by referring these patients for specialist cessation advice?
BACKGROUND: Studies of neuropsychological outcome following coronary artery bypass graft surgery (CABG) have traditionally dichotomised patients as "impaired" or "unimpaired". This conceals the potential heterogeneity of deficits due to different mechanisms and sites of brain injury. OBJECTIVES: To explore neuropsychological outcome following CABG and determine to what extent it conforms to prototypic cortical and/or subcortical neurobehavioral syndromes and whether different intraoperative physiologic measures are associated with different subtypes of neuropsychological outcome. METHODS: Neuropsychological tests were administered to 85 patients before and after elective CABG and to 50 matched normal control subjects. Pre- to postoperative change scores were computed using standardised regression based norms. Change scores on selected memory measures were subjected to cluster analysis to identify qualitatively distinct subtypes of memory outcome. Emergent clusters were compared on non-memory measures, intraoperative physiologic measures, and demographic variables. RESULTS: Three subtypes of memory outcome were identified: memory spared (48% of patients), retrieval deficit (35%), and encoding/storage deficit (17%). Contrary to expectation, the subgroups were indistinguishable on measures of confrontation naming and manual dexterity and on intraoperative cardiac surgical physiologic measures and demographic variables. The encoding/storage deficit subgroup exhibited executive dysfunction. CONCLUSIONS: Heterogeneous profiles of neuropsychological dysfunction were found following CABG although they did not tightly conform to prototypic cortical and subcortical neurobehavioral syndromes. This challenges the value and appropriateness of the common practice of collapsing individual test scores to arrive at a single figure to define "impairment". Whether different subtypes of neuropsychological outcome are caused by different pathophysiologic mechanisms remains unknown.
BACKGROUND: Epidemiological studies have reported associations between reduced cardiovascular disease and diets rich in tomato and/or lycopene. Intervention studies have shown that lycopene-containing foods may reduce cholesterol levels and lipid peroxidation, factors implicated in the initiation of cardiovascular disease. The objective of this study was to determine whether consumption of lycopene rich foods conferred cardiovascular protection to middle-aged adults as indicated by plasma lipid concentrations and measures of ex vivo antioxidants. METHODS: Ten healthy men and women consumed a low lycopene diet with no added lycopene (control treatment) or supplemented with watermelon or tomato juice each containing 20 mg lycopene. Subjects consumed each treatment for three weeks in a crossover design. Plasma, collected weekly was analyzed for total cholesterol, high density lipoprotein cholesterol (HDL-C) and triglyceride concentrations and for the antioxidant biomarkers of malondialdehyde formation products (MDA), plasma glutathione peroxidase (GPX) and ferric reducing ability of plasma (FRAP). Data were analyzed using Proc Mixed Procedure and associations between antioxidant and lipid measures were identified by Pearson's product moment correlation analysis. RESULTS: Compared to the control diet, the lycopene-containing foods did not affect plasma lipid concentrations or antioxidant biomarkers. Women had higher total cholesterol, HDL-C and triglyceride concentrations than did the men. Total cholesterol was positively correlated to MDA and FRAP while HDL-C was positively correlated to MDA and GPX. GPX was negatively correlated to triglyceride concentration. CONCLUSIONS: The inclusion of watermelon or tomato juice containing 20 mg lycopene did not affect plasma lipid concentrations or antioxidant status of healthy subjects. However, plasma cholesterol levels impacted the results of MDA and FRAP antioxidant tests.
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To quantify our decision for the removal of glucose and the use of mannitol as a substitute osmotic agent in the cardiopulmonary bypass prime, we conducted a prospective clinical audit to evaluate the effects of this change on patient outcomes. Data were prospectively collected for 172 consecutive routine cardiac surgery patients. The first 85 patients (Surgeon A, 42 patients [Group 1], Surgeon B, 43 patients [Group 2]) received 1000 mL Plasmalyte 148 + 5% glucose as per institutional protocol. The remaining priming volume for each group consisted of 500 mL hemaccel or 4% albumin, 50 mL 8.4% sodium bicarbonate, 100 mL Hartmann's solution. The change to a glucose-free prime was then initiated, substituting Plasmalyte 148 (without 5% glucose) for the Plasmalyte 148 + 5% glucose, in addition 12.5 g mannitol was administered following delivery of cardioplegia to the patients operated on by Surgeon B. Surgeon A would not include mannitol at this time. Forty-one patients operated by Surgeon A (Group 3) subsequently received Plasmalyte 148, and 46 patients operated on by Surgeon B (Group 4) received Plasmalyte 148 plus mannitol. Analysis was performed stratified by surgeon to quantify the effects of removing glucose from the prime. Comparisons were made between groups 1 and 3, and 2 and 4. Net fluid changes were recorded from pre-CPB, up to 24-h postoperatively. Intraoperative data collection included serum glucose, hematocrit, osmolality, return to rhythm, arrhythmias, and blood transfusions. Post-operative variables, including cardiac enzymes, arrhythmias, intubation time, length of stay, and mortality were also collected. Removal of glucose from the CPB prime resulted in a lower serum glucose concentration (mmol/L) during CPB (Gp 1 [13.6] vs. Gp 3 [5.4]; Gp 2 [14.7] vs. Gp 4 [5.4], p < .05). The addition of 12.5 g of mannitol to the CPB prime resulted in a significantly lower net fluid gain (mL) 24 h postoperatively (Gp 2[2792] vs. Gp 4 [1970], p < .05) and greater CPB hematocrit (%) (Gp 2 [24.3] vs. Gp 4 [26], p < .05). No other results were found to be significant (except CPB plasma osmolality (Groups 2 and 4) and sodium concentration [Groups 1 and 3]). The results of our audit provide an evidence base to support our change in practice to utilize nonglucose primes.
A preliminary survey demonstrated activity for alpha-D-glucosidase, alpha-D-mannosidase, alpha-L-arabinosidase, beta-D-glucosidase, beta-D-xylosidase, and beta-D-galactosidase in orange fruit flavedo and albedo tissue. alpha-L-Rhamnosidase was not detected. Subsequently, a beta-glucosidase was purified from mature fruit rag tissue (composed of intersegmental septa, squeezed juice sacs, and fruit core tissue) of Citrus sinensis var. Valencia. The beta-glucosidase exhibited low levels of activity against p-nitrophenyl-beta-D-fucopyranoside (13.5%) and p-nitrophenyl-alpha-D-glucopyranoside (7.0%), compared to its activity against p-nitrophenyl-beta-D-glucopyranoside (pNPG, 100%). The enzyme was purified by a combination of ion exchange (anion and cation) and gel filtration (Superdex and Toyopearl HW-55S) chromatography. It has an apparent molecular mass of 64 kDa by denaturing electrophoresis or 55 kDa by gel filtration chromatography (BioGel P-100). Hydrolysis of pNPG demonstrated a pH optimum between 4.5 and 5.5. At pH 5.0 the temperature optimum was 40 degrees C. At pH 5.0 and 40 degrees C the K(m) for pNPG was 0.1146 mM and it had a V(max) of 5.2792 nkatal x mg(-1) protein (katal = 0.06 International Units = the amount of enzyme that produces, under standard conditions, one micromol of product per min). Of the substrates tested, the enzyme was most active against the disaccharide cellobiose (1-->4), but was not active against p-nitrophenyl-beta-D-cellobioside. High levels of activity also were observed with the disaccharides laminaribiose (1-->3), gentiobiose (1-->6), and sophorose (1-->2). Activity greater than that observed with pNPG was obtained with the flavonoids hesperetin-7-glucoside and prunin (naringenin-7-glucoside), salicin, mandelonitrile-beta-D-glucoside (a cyanogenic substrate), and sinigrin (a glucosinolate). The enzyme was not active against amygdalin, coniferin, or limonin glucoside.
BACKGROUND: There is convincing evidence to suggest that depression significantly increases the risk of mortality following myocardial infarction. There are few data concerning depression as a risk factor for mortality following cardiac surgery. The aim of the present observational study was to determine if preoperative depressive symptoms resulted in an increased risk of late mortality following cardiac surgery. METHODS: Preoperative assessments of depressive symptoms were performed on 158 patients undergoing coronary artery bypass surgery. Elevated preoperative depression symptoms were defined as a depression anxiety stress scale score of > or = 10. RESULTS: Twenty-four of the 158 patients ( 15.2%) were classified as having elevated preoperative depressive symptoms. Patients were followed for a median of 25 months (range: 4-38 months). Three of the 24 patients (12.5%) with preoperative depressive symptoms died within the follow-up period, compared with three of the 134 (2.2%) non-depressed patients (odds ratio: 6.24; 95% CI: 1.18-32.98; P = 0.046). There were no other group differences on variables including population demographics, medical risk factors, surgical parameters, and indices of postoperative morbidity. CONCLUSIONS: Elevated depressive symptoms before coronary bypass surgery may be a significant predictor of late death. Prospective studies evaluating the prevalence of depressive symptoms in cardiac surgical patients and their effect on long-term outcome must be undertaken.
1. Evidence suggesting the presence of coronary artery baroreceptors on coronary arteries has existed for over 30 years. 2. Evidence that activation of ventricular mechanoreceptors can elicit cardiovascular changes has been challenged, with those changes now thought to be due to coronary artery mechanoreceptors. 3. Studies have suggested that coronary artery mechanoreceptors act as coronary baroreceptors with a role in cardiovascular regulation. However, all evidence to date has been obtained in anaesthetized animal models in physiologically compromised intra-operative states. 4. The purpose of the present study was to design an ovine model that would allow the discrete stretch of coronary arteries without causing ischaemia or changing flow or intra-arterial pressure and that would confirm results seen in previous studies. In addition, the possibility that the technique could be used for studies of coronary artery baroreflexes in conscious sheep was investigated. 5. Controlled stretch of the proximal left anterior descending coronary artery elicited decreases in arterial pressure without changes in heart rate or electrocardiographic activity in halothane-anaesthetized sheep. Similar results were demonstrated in conscious sheep after surgical recovery of up to 2 weeks. 6. The present study supports the possibility that coronary artery baroreceptors exist and likely have a role in cardiovascular regulation. The results of the present study in anaesthetized sheep are in agreement with previous results in anaesthetized animals, but also provide the first demonstration of coronary baroreceptor activity in a conscious animal model, underscoring the potential use of the model in the study of coronary artery baroreceptors in the intact animal.
OBJECTIVE: To compare the incidence of neuropsychologic deficits 1 week and 6 months after coronary artery bypass graft (CABG) surgery (extracardiac) and valve surgery with or without CABG surgery (intracardiac) using reliable change indices to define the incidence of neuropsychologic deficits. DESIGN: Prospective study. SETTING: Cardiac surgical unit in a university teaching hospital. PARTICIPANTS: Patients scheduled for elective multiple-graft (> or =3 grafts) CABG surgery (n = 59), or elective valve surgery (with or without concomitant CABG surgery) (n = 50) and a matched sample of nonsurgical controls (n = 53). INTERVENTIONS: Neuropsychologic assessments were performed 1 day before surgery, 7 days and 6 months after surgery. MEASUREMENTS AND MAIN RESULTS: The 7-day assessment showed no significant differences between valve surgery patients and CABG surgery patients in the incidence of neuropsychologic deficits. When reassessed 6 months postoperatively, the valve group displayed a significantly higher incidence of deficits on the digit symbol test compared with the CABG group (valve 26.7% v CABG 6.8%). In the CABG group, there was a significant change in the incidence of deficits per patient from 7 days to 6 months (p = 0.03) that was not evident in the valve group. CONCLUSION: There are some differences in the neuropsychologic outcome of extracardiac and intracardiac surgery. Patients undergoing isolated CABG surgery showed a greater reduction in the incidence of persisting deficits at 6 months than patients undergoing valve surgery with or without CABG surgery. This finding warrants further investigation, with particular attention to patients undergoing combined valve and coronary artery procedures.
It is well recognized that cardiac surgery with cardiopulmonary bypass can potentially induce a wide spectrum of central nervous system (CNS) sequelae. Our awareness of the prevalence of these CNS complications is dependent on the validity of the available diagnostic methods. Current assessment methods designed to detect both focal and diffuse cerebral ischemia include neurologic examination, imaging techniques, biochemical markers, neuropsychologic assessment, and patient perceived outcomes. These techniques vary in their sensitivity and specificity, as well as feasibility for use in everyday clinical practice. There are currently only limited standardized methodologic guidelines for the assessment of CNS complications after cardiac surgery, which has resulted in considerable interstudy variability in the identification and reporting of outcomes. The application of clearly definable endpoints for reporting of CNS outcomes would be beneficial. The wealth of available data suggests that the incidence of overt CNS injury such as stroke has declined since the 1980s and is now approximately 2%, whereas evidence suggests that up to one third of cardiac surgery patients experience postoperative cognitive deficits. One of the clear strengths of the current era is the recognition of CNS injury associated with cardiac surgery, and the quest to improve our understanding of these outcomes. The application of more uniform assessment and reporting practices is surely vital to the continued advancement of cardiac surgery.
INTRODUCTION: The aim of this study was to determine if coronary artery bypass graft (CABG) surgery performed utilizing the Octopus II stabilizing system provides myocardial and cerebral protection comparable to traditional CABG surgery utilizing cardiopulmonary bypass (CPB). METHODS: Elective patients requiring surgery for double or triple vessel disease were randomized to receive either conventional CABG with CPB (n = 14) or OPCAB using the Octopus II stabilizing system (n = 12), after receiving institutional approval and written consent. Exclusion criteria included previous cardiac surgery, recent myocardial infarction, and previous cerebrovascular disease. Troponin T (TnT) was measured preoperatively and at 2, 4, 6, 8, 10, 12, 24, and 72 hours after initiation of grafting. Neuropsychological assessments (10 measures) were performed in the week prior to surgery, one week, and six months after surgery. RESULTS: Troponin T release was reduced in the OPCAB patients at all time points (repeated measures ANOVA p = 0.043), reaching significance at 8, 10 and 12 hours (p = 0.033, 0.038, 0.019). Other factors (composite clinical end point (prolonged LOS or ICU stay or 30-day mortality), infarction, and intubation time) did not show any significant differences between the two groups. The incidence of neuropsychological deficits was not different between the two groups at both seven-day and six-month follow-up assessments. CONCLUSIONS: Decreased TnT release suggests a myocardial benefit for the OPCAB procedure. A neuropsychological benefit remains to be demonstrated.
Site-specific recombinases XerC and XerD function in the segregation of circular bacterial replicons. In a recombining nucleoprotein complex containing two molecules each of XerC and XerD, coordinated reciprocal switches in recombinase activity ensure that only XerC or XerD is active at any one time. Mutated recombinases that carry sub?stitutions of a catalytic arginine residue stimulate cleavage and strand exchange mediated by the partner recombinase on DNA substrates that are normally recombined poorly by the partner. This is associated with a reciprocal impairment of the recombinase's own ability to initiate catalysis. The extent of this switch in catalysis is modulated by changes in recombination site sequence and is not a direct consequence of any catalytic defect. We propose that altered interactions between the mutated proteins and their wild-type partners lead to an increased level of an alternative Holliday junction intermediate that has a conformation appropriate for resolution by the partner recombinase. The results indicate how subtle changes in protein-DNA architecture at a Holliday junction can redirect recombination outcome.
OBJECTIVES: mood disorders and neuropsychological deficits are both commonly reported occurrences after cardiac surgery. We examined the relationship between mood state and postoperative cognitive deficits in this population. METHODS: assessments of neuropsychological functions and mood state (depression, anxiety, stress scales; DASS) were performed preoperatively and postoperatively on 147 patients undergoing cardiac surgery. RESULTS: the incidence of preoperative depression, anxiety, and stress symptomatology was 16%, 27%, and 16%, respectively. The incidence of postoperative anxiety symptomatology significantly increased to 45% (p<0.001), while the incidence of depression and stress symptomatology remained stable (19% and 15%, respectively; ns). Changes in mood state did not influence changes in neuropsychological performance. Preoperative mood was a strong predictor of postoperative mood, and was related to postoperative deficits on measures of attention and memory. CONCLUSIONS: an assessment of preoperative mood is critical in identifying patients at risk of postoperative mood disorders and neuropsychological deficits. Measures assessing somatic manifestations of anxiety may not be suitable for a surgical population.
In rats, circulating corticosterone and insulin are involved in regulation of the hypothalamic neuropeptide Y (NPY) system, which in turn, is involved in regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Since the HPA axis and stress responsivity is altered in diseases such as depression, we investigated interactions between the effects of stress and antidepressant drug treatment on arcuate nucleus and locus coeruleus NPY mRNA expressions using in-situ hybridization histochemistry. After acute (2 h) and repeated immobilization (2 h daily, for 14 days), plasma concentrations of corticosterone increased, and those of insulin decreased. The expression of NPY mRNA was significantly increased in the arcuate nucleus, but was unchanged in the locus coeruleus following acute and repeated immobilization. Adrenalectomized rats with systemic corticosterone replacement (ADX+CORT), whose corticosterone concentration was maintained at approximately 50-100 ng/ml during repeated stress, showed a decrease in plasma insulin and an increase in arcuate nucleus NPY mRNA similar to that observed in sham rats, suggesting that changes in NPY mRNA levels are more closely tied to circulating insulin than to circulating corticosterone. In contrast, locus coeruleus NPY mRNA expressions in ADX+CORT rats were significantly higher than those in sham rats after repeated stress. Desmethylimipramine (DMI) treatment for 24 days did not affect basal plasma concentrations of corticosterone or insulin, or arcuate nucleus NPY mRNA expressions, but significantly decreased basal levels of locus coeruleus NPY mRNA compared to saline-treated rats. After repeated immobilization (2 h daily, for 4 days), DMI significantly reduced the stress-induced rise in locus coeruleus NPY mRNA levels, but potentiated the stress-induced rise in arcuate nucleus NPY mRNA expression. These results demonstrate that: (1) the increase in arcuate nucleus NPY mRNA expressions in stressed rats closely follows the decrease in plasma concentrations of insulin; (2) increases in NPY mRNA expressions occur in the absence of changes in plasma corticosterone; and (3) desipramine treatment potentiated the effect of stress on arcuate nucleus NPY mRNA expressions, but blocked the repeated stress-induced increase in locus coeruleus NPY mRNA expressions. Thus, NPY mRNA expression in the arcuate nucleus and the locus coeruleus is sensitive to the effects of stress and to the antidepressant drug desipramine, but the arcuate nucleus NPY system is regulated by different mechanisms than the locus coeruleus NPY system. The results provide further evidence for the importance of circulating insulin in the regulation of the arcuate nucleus NPY system.
BACKGROUND: The authors conducted a study to determine if reducing mandibular denture movement through the use of a denture adhesive improves chewing function in edentulous patients. METHODS: The authors compared the mean chewing rates of 10 denture wearers who used and did not use a denture adhesive with that of a control group of 10 dentate people. The authors recorded mandibular movements using a multichannel magnetometer tracking system while the subjects chewed standardized pieces of dried apricots and fresh white bread. They made recordings for the test subjects without the use of denture adhesive and at zero, two and four hours after Fixodent denture adhesive cream (Procter & Gamble Co.) was applied to the mandibular denture. RESULTS: The mean chewing rate for the control group was significantly faster than that of the test group at baseline (P < .01). The authors found statistically significant increases in the mean chewing rates for the test group after the denture adhesive was applied at all time points for both foods. None of the after--adhesive-application rates were significantly different from the control group's rate (P > .05). CONCLUSIONS: Use of denture adhesive increased the mean chewing rate in test subjects immediately after and at two and four hours after denture adhesive was applied to a rate that approximated that observed in control subjects (P > .05). CLINICAL IMPLICATIONS: These findings show that using a denture adhesive promotes a faster and more natural rate of chewing.