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Biomedical subjects

P M Walker

Publications and source records attributed to P M Walker.

At least 19 recordsLinked to original sources
PubMed2002

Early-weaning and postweaning nutritional management affect feedlot performance, carcass merit, and the relationship of 12th-rib fat, marbling score, and feed efficiency among Angus and Wagyu heifers.

Twelve 3/4 Angus (Angus) and 12 Wagyu-cross (1/2 Wagyu x 1/2 Angus) (Wagyu) heifers were weaned at 180 d of age and grazed on endophyte-infected tall fescue for 16 mo before entering the feedlot as 2-yr-olds. Twelve 3/4 Angus heifer calves and 12 Wagyu-cross heifer calves from the following year's calf crop were weaned at 142 +/- 4.1 d of age, immediately adjusted to an 80% concentrate diet, and finished as calves. All heifers were fed a common finishing diet until an estimated 50% of their respective group would grade USDA low Prime or better based on ultrasound predictions. Ultrasound measurements of s.c. and i.m. fat depots were recorded at 60-d intervals throughout the finishing period. Heifers finished as calves had higher (P = 0.02) marbling scores at any given fat thickness and gained more efficiently (P < or = 0.01) at any given marbling score than heifers finished as 2-yr-olds. Gain:feed decreased quadratically (P < or = 0.05) as 12th-rib fat thickness increased for Angus and Wagyu heifers. Gain:feed decreased linearly (P < or = 0.01) for Wagyu calves and quadratically (P < or = 0.01) for Angus calves as 12th-rib fat thickness increased. However, these differences in slope were not different (P = 0.34) as a result of breed among heifers finished as calves. Marbling score increased linearly (P < or = 0.01) as 12th-rib fat thickness increased for Angus and Wagyu heifers finished as 2-yrolds or as calves. However, Wagyu heifers, regardless of age at feedlot entry, had a higher marbling score (P < or = 0.05) at any given 12th-rib fat thickness than Angus heifers. Finishing early-weaned heifers as calves as opposed to 2-yr-olds results in i.m. fat deposition during a period of more efficient growth. Additionally, including Wagyu genetics into the breeding of early-weaned heifers finished as calves or as 2-yr-olds results in higher marbling scores at any 12th-rib fat thickness.

Adipose Tissue↗
PubMed2001

Detection and prediction of acute heart transplant rejection with the myocardial T2 determination provided by a black-blood magnetic resonance imaging sequence.

OBJECTIVES: This study aimed to determine whether the myocardial T2 relaxation time, determined using a black-blood magnetic resonance imaging (MRI) sequence, could predict acute heart transplant rejection. BACKGROUND: The use of black-blood MRI sequences allows suppression of the confusing influence of blood signal when myocardial T2 is calculated to detect myocardial edema. METHODS: A total of 123 investigations, including cardiac MRI and myocardial biopsy, were performed 8 +/- 11 months after heart transplantation. Myocardial T2 was determined using an original inversion-recovery/spin-echo sequence. RESULTS: A higher than normal T2 (> or = 56 ms) allowed an accurate detection of the moderate acute rejections evidenced at baseline biopsy (> or = International Society for Heart and Lung Transplantation grade 2): sensitivity, 89% and specificity, 70% (p < 0.0001). T2 was increased in grade 2 (n = 11) compared with grade 0 (n = 49, p < 0.05), grade 1A (n = 34, p < 0.05) and grade 1B (n = 21, p < 0.05); T2 was further increased in grade 3 (n = 8) compared with grade 2 (p < 0.05). In addition, in patients without rejection equal to or greater than grade 2 at baseline, a T2 higher than normal (> or = 56 ms) was correlated with the subsequent occurrence of equal or greater than grade 2 rejection within the next three months: sensitivity 63% (12/19) and specificity 78% (64/82) (p = 0.001). CONCLUSIONS: Myocardial T2 determined using a black-blood MRI sequence, is sufficiently sensitive to identify most of the moderate acute rejections documented with biopsy at the same time, but is also a predictor of the subsequent occurrence of such biopsy-defined rejections.

Adolescent↗
PubMed2001

Static quadrupole moment of the five-quasiparticle k = 35/2 isomer in (179)w studied with the level-mixing spectroscopy method.

The spectroscopic quadrupole moment of the high-spin, high- K five-quasiparticle isomer (K(pi) = 35/2(-), T(1/2) = 750(80) ns, E(i) = 3349 keV) in (179)W has been determined using the level mixing spectroscopy method. A value Q(s) = 4.00(+0.83-1.06)e b was derived, which corresponds to an intrinsic quadrupole moment Q0 = 4.73(+0.98-1.25)e b and to a quadrupole deformation beta(2) = 0.185(+0.038-0.049). These values differ significantly from the deduced ground-state quadrupole moments and are in disagreement with the current theoretical predictions in this mass region.

Journal Article↗
PubMed2001

Hemorrhage-induced alpha-adrenergic signaling results in myocardial TNF-alpha expression and contractile dysfunction.

Hemorrhagic shock (HS), secondary to major blood loss, frequently precedes multiple organ dysfunction and is accompanied by a surge in circulating catecholamine levels. Expression of the cardiodepressant cytokine, tumor necrosis factor-alpha (TNF-alpha), has been observed in the heart after HS and resuscitation (HS/R) and alpha(1)-adrenergic blockade prevented translocation of the nuclear transcription factor, NF-kappa B, to the nucleus. We hypothesized that alpha(1)-adrenergic stimulation induces myocardial TNF-alpha expression, which results in depressed cardiac function after HS/R. The role of alpha(1)-adrenergic stimulation in myocardial TNF-alpha expression and depressed cardiac function after HS/R was assessed by treatment with the alpha(1)-adrenergic inhibitor, prazosin hydrochloride (1 mg/kg ip), for 1 h before the onset of hemorrhage. In addition, TNF-alpha was neutralized with a specific antibody (600 microl/kg iv) 5 min before hemorrhage. HS was induced by the withdrawal of blood to a mean blood pressure of 50 mmHg for 1 h. Contractile function was measured with the use of a Langendorff apparatus 2 h after the end of HS. HS/R led to significant decreases in left ventricular developed tension and in the maximal rate of pressure increase over time during both contraction and relaxation. Myocardial expression of TNF-alpha measured by enzyme-linked immunosorbent assay increased significantly after 30 min of hemorrhage and peaked after 60 min of HS and 45 min of resuscitation. Depression in cardiac function after HS/R was reversed by 85% in hearts from rats treated with a TNF-alpha neutralizing antibody and by 90% in hearts from rats treated with prazosin hydrochloride. We conclude that HS activates a alpha(1)-adrenergic pathway, resulting in TNF-alpha expression in the heart and depressed myocardial contractile function.

Adrenergic alpha-Agonists↗
PubMed2001

Early weaning and postweaning nutritional management affect feedlot performance of angus x simmental heifers and the relationship of 12th rib fat and marbling score to feed efficiency.

Early-weaned Angus x Simmental heifers were used to evaluate the effects of postweaning nutritional management on feedlot performance, carcass merit, and the relationship of intramuscular and subcutaneous fat deposition to the feed efficiency among heifers fed for a high-quality market. Sixteen heifers were weaned at 73+/-5.5 d of age and grazed on endophyte-infected tall fescue for 18 mo before entering the feedlot (early-weaned-P). Eighty heifers from the following year's calf crop were weaned at 71+/-5.5 d of age and allowed either ad libitum access to a 25% concentrate diet (early-weaned-25C) or limit-fed a 90% concentrate diet (early-weaned-90C) to achieve a similar ADG. Following a 119-d growing period, 16 early-weaned-90C and 16 early-weaned-25C calves were paired based on BW and growth rate and individually fed during the finishing period along with the early-weaned-P heifers. Ultrasound measurements of s.c. and i.m. fat were recorded at approximately 60-d intervals throughout the finishing period. Feed efficiency was regressed against s.c. and i.m. fat, and i.m. fat was regressed on s.c. fat. Despite a similar ADG, early-weaned-90C calves gained more efficiently (P < or = 0.05) in the feedlot than early-weaned-25C calves. Heifers finished as yearlings tended (P < or = 0.10) to gain faster but gained less efficiently (P < or = 0.01) than early-weaned-90C heifers finished as calves. The rate of s.c. and i.m. fat deposition was similar between early-weaned-90C and early-weaned-25C heifer calves. The calves were grouped together for comparison to yearlings. Feed efficiency decreased quadratically (P < or = 0.01) as s.c. fat cover increased. The rate at which feed efficiency decreased relative to increasing s.c. fat cover was similar regardless of age at feedlot entry. However, heifers finished as calves gained more efficiently (P < or = 0.01) than yearlings at any given fat thickness. Feed efficiency decreased linearly (P < or = 0.01) as i.m. fat increased among heifers finished as calves. Additionally, heifers finished as calves deposited i.m. fat at a faster rate relative to s.c. fat (P < or = 0.01) than yearlings. These data suggest that heifers finished as calves produce high-quality carcasses with less s.c. fat cover while gaining more efficiently than heifers finished as yearlings.

Adipose Tissue↗
PubMed2000

Surgeon compensation and motivation.

HYPOTHESIS: Financial incentives are the only form of compensation that will motivate surgeons at an academic health sciences center to perform the tasks outlined in the hospital's mission statement. DESIGN: A questionnaire divided into 5 sections: demographics, compensation, time allocation, benefits and incentives, and motivational factors. SETTING: The Department of Surgery, The Toronto Hospital, Toronto, Ontario. PARTICIPANTS: All academic surgeons (N=64) practicing at The Toronto Hospital in July 1997. RESULTS: Of the 64 eligible mailed surveys, there were responses for 59. Of these 59 surgeons, 48 (81%) receive compensation through a fee-for-service method. However, only 32 (54%) of the surgeons prefer the fee-for-service method, while 18 (31%) prefer salary and 9 (15%) prefer an alternative system. On average, these academic surgeons spend 44% of their time teaching or performing research, for which they receive 14% of their total income. Of the motivational factors assessed, financial bonuses are a positive motivational factor for all "surgeon tasks." In addition, task-specific motivational factors were established for research, teaching, and operating, including research facilities, mentorship and prestige, and interesting case types, respectively. CONCLUSIONS: Surgeons are not appropriately renumerated for time spent on academic activities, and many would prefer an alternative form of compensation to the fee-for-service method. Knowledge that surgeons are receptive to tasks supporting the hospital's mission statement leads us to conclude that appropriate motivation can shape the activity of academic surgeons. Financial rewards ranked the highest as a motivational factor for all surgeon tasks; however, task-specific motivational factors were identified. Overall, multiple factors, specifically targeted to the individual, will serve to motivate. Thus, compensation packages based on individual preferences and personal motivational factors will be the most successful.

Academic Medical Centers↗
PubMed2000

Role of TNF-alpha in myocardial dysfunction after hemorrhagic shock and lower-torso ischemia.

Ruptured abdominal aortic aneurysm (RAAA) repair, a combination of hemorrhagic shock and lower-torso ischemia, is associated with a 50-70% mortality. Myocardial dysfunction may contribute to the high rate of mortality after aneurysm repair. We attempted to determine whether RAAA repair results in cardiac dysfunction mediated by tumor necrosis factor-alpha (TNF-alpha). We modeled aortic rupture and repair in the rat by inducing hemorrhagic shock to a mean blood pressure of 50 mmHg for 1 h, followed by supramesenteric clamping of the aorta for 45 min. After 90 min of reperfusion, cardiac contractile function was assessed with a Langendorff preparation. Myocardial TNF-alpha, ATP and creatine phosphate (CP) levels, and markers of oxidant stress (F(2)-isoprostanes) were measured. Cardiac function in the combined shock and clamp rats was significantly depressed compared with sham-operated control rats but was similar to that noted in animals subjected to shock alone. Myocardial TNF-alpha concentrations increased 10-fold in the combined shock and clamp rats compared with sham rats, although there was no difference in myocardial ATP, CP, or F(2)-isoprostanes. TNF-alpha neutralization improved cardiac function by 50% in the combined shock and clamp rats. Hemorrhagic shock is the primary insult inducing cardiac dysfunction in this model of RAAA repair. An improvement in cardiac contractile function after immunoneutralization of TNF-alpha indicates that TNF-alpha mediates a significant portion of the myocardial dysfunction in this model.

Adenosine Triphosphate↗
PubMed1999

Lower limb ischemia: phase 1 results of salvage perfusion.

Revascularization of an ischemic lower extremity is associated with high morbidity (20-30%) and perioperative mortality (10-20%) regardless of the mode of intervention, surgical or thrombolytic, considered to be due to polymorphonuclear (PMN) activation and mediator release. In this study, the safety and feasibility of cell-free extracorporeal perfusion of the limb with a solution designed to minimize both local and systemic injury was tested. Methods. Patients with severe limb ischemia (sensory/motor loss, rest pain/gangrene) were studied prospectively by random assignment into the treatment arm (n = 14) or control arm (n = 21). Surgical management consisted of restorative procedure, thrombectomy or embolectomy (n = 21), or reconstruction (n = 14). Reperfusion of the ischemic limb was achieved with hypertonic, hyperoncotic perfusate containing anti-oxidants delivered via the arterial tree (mean volume 1835 +/- 824 ml) with initial venous drainage (mean volume 775 +/- 263 ml) in the restorative group. Means were compared by paired t test. Results. No adverse systemic effects were detected after limb perfusion (electrolytes, coagulation, platelet function, CBC). Rapid lactate wash-out was observed within 30 min of perfusion (preperfusion 3.2 +/- 4.1 mM, 30 min postperfusion 0.7 +/- 0.71 mM, P < 0.01). Blunting of PMN activation was shown by chemiluminescence (CL) analysis (preischemic CL: 0.68 +/- 0.2; 30 min CL: 0.47 +/- 0. 2; P < 0.013). F2-isoprostanes, a marker of free radical-mediated systemic lipid peroxidation, were significantly reduced in patients treated with study perfusion method (70.55 +/- 39.54 versus control 194.38 +/- 25.24, P < 0.005). Mortality with treatment was 0/14 versus 5/21 in the control. Complication frequency: MI 0/14 vs 3/21; renal 0/14 vs 1/21; leg edema 1/14 vs 5/21; amputations 2/14 vs 1/21. Conclusion. Modification of limb perfusion in patients with severe limb ischemia, using our simple and rapid (15-20 min) method provides beneficial systemic effects.

Cohort Studies↗
PubMed1999

Ruptured abdominal aortic aneurysm, a "two-hit" ischemia/reperfusion injury: evidence from an analysis of oxidative products.

PURPOSE: Ruptured abdominal aortic aneurysm (RAAA) remains a lethal condition despite improvements in perioperative care. The consequences of RAAA are hypothesized to result from a combination of two ischemia/reperfusion events: hemorrhagic shock and lower torso ischemia. Ischemia/reperfusion results in tissue injury by diverse mechanisms, which include oxygen free radical-mediated injury produced from activated neutrophils, xanthine oxidase, and mitochondria. Oxygen-free radicals attack membrane lipids, resulting in membrane and subsequently cellular dysfunction that contributes to postoperative organ injury/failure. The purpose of this investigation was to quantify the oxidative injury that occurs as a result of the ischemia/reperfusion events in RAAAs and elective AAAs. METHODS: Blood samples were taken from 22 patients for elective AAA repair and from 14 patients for RAAA repair during the perioperative period. Plasma F(2)-isoprostanes were extracted, purified, and measured with an enzyme immunoassay. Aldehydes and acyloins were purified and quantified. Neutrophil oxidative burst was measured in response to a receptor independent stimulus (phorbol 12-myristate 13-acetate) with luminol-based chemiluminescence. RESULTS: Plasma from patients with RAAAs showed significantly elevated F(2)-isoprostane levels on arrival at hospital and were significantly elevated as compared with the levels of patients for elective repair throughout the perioperative period (two-way analysis of variance, P <.0001). Multiple regression showed a significant relationship between the phagocyte oxidative activity and F(2)-isoprostane levels (P <.013). Total acyloin levels were significantly higher in patients with RAAAs as compared with the levels in elective cases. CONCLUSION: The F(2)-isoprostane levels, specific markers of lipid peroxidation, showed that patients with RAAAs had two phases of oxidative injury: before arrival at hospital and after surgery. The significant relationship between the postoperative increases in F(2)-isoprostane levels and the neutrophil oxidant production implicates neutrophils in the oxidative injury that occurs after RAAA. New therapeutic interventions that attenuate neutrophil-mediated oxidant injury during reperfusion may decrease organ failure and ultimately mortality in patients with RAAAs.

Aldehydes↗
PubMed1999

Automatic detection of left ventricular contours from cardiac cine magnetic resonance imaging using fuzzy logic.

RATIONALE AND OBJECTIVES: Gated cardiac cine magnetic resonance imaging provides accurate dynamic data of the left ventricular function. However, the manual extraction of important physiologic parameters such as myocardium wall thickness and left ventricular volumes is invariably time consuming and subjective. To reduce the variability and time constraints inherent in observer contour tracing, the authors developed an automatic left ventricle contour-detection method. METHODS: The purpose was to apply fuzzy logic-based automatic contour detection to identification of endocardial and epicardial borders in short-axis magnetic resonance images. The automatic contouring was compared with manual tracing using the calculated ejection fraction as the comparison criterion. RESULTS: A good correlation was found between the two approaches (r2 = 0.98). CONCLUSIONS: The ejection fraction can be obtained using this automatic contouring method.

Adult↗
PubMed1999

MR imaging of the heart in patients after myocardial infarction: effect of increasing intersection gap on measurements of left ventricular volume, ejection fraction, and wall thickness.

PURPOSE: To determine the extent to which the number of planes imaged at magnetic resonance (MR) imaging could be reduced without modifying the calculated volume and thickness of the left ventricle. MATERIALS AND METHODS: Sixty-one patients were examined after a myocardial infarction. The whole left ventricle was imaged by using 5-mm contiguous breath-hold cine MR short-axis sections with no gap (SAng) (two-dimensional fast low-angle shot sequence, 9/4.8 [repetition time msec/echo time msec]). The effect of omitting one section in two (short-axis sections with 5-mm gap [SA5 mm]) or two sections in three (short-axis sections with 10-mm gap [SA10 mm]) was studied. RESULTS: In the comparison of SA5 mm or SA10 mm with respect to the reference SAng, the standard error of the estimate (SEE) for the diastolic volume did not exceed the 6.1% interobserver SEE, and the SEE for the ejection fraction remained lower than the 3% interobserver SEE. The measured wall thickness was not affected. In addition, six simple geometric models were compared with SAng and yielded an SEE of 9.5%-28.1% for the diastolic volume and 3.8%-13.3% for the ejection fraction. CONCLUSION: In the study of left ventricles with heterogeneous contractility, short-axis imaging is more accurate than geometric modeling and permits wall thickness measurements when an intersection gap of 5 or 10 mm is used.

Adult↗
PubMed1999

A CD18 monoclonal antibody reduces multiple organ injury in a model of ruptured abdominal aortic aneurysm.

The role of CD18 antibody (anti-CD18) in remote and local injury in a model of ruptured abdominal aortic aneurysm repair was investigated. Rats were divided into sham, shock, clamp, and shock + clamp groups. Shock + clamp animals received anti-CD18 or a control monoclonal antibody. One hour of hemorrhagic shock was followed by 45 min of supramesenteric aortic clamping. Intestinal and pulmonary permeability to (125)I-labeled albumin was determined. Myeloperoxidase (MPO) activity, F(2)-isoprostane levels, and transaminases were also measured. Only shock + clamp resulted in statistically significant increases in pulmonary and intestinal permeability, which were associated with significant increases in MPO activity and F(2)-isoprostane levels. Treatment with anti-CD18 significantly decreased intestinal and pulmonary permeability in shock + clamp animals. These reductions were associated with significantly reduced intestinal and hepatic MPO activity and pulmonary F(2)-isoprostane levels and reduced alanine and aspartate aminotransferase levels; however, anti-CD18 had no effect on intestinal or hepatic F(2)-isoprostane levels or on pulmonary MPO activity. These results suggest CD18-dependent and -independent mechanisms of local and remote organ injury in this model of ruptured abdominal aortic aneurysm.

Alanine Transaminase↗
PubMed1998

A rapid assay of endotoxin in whole blood using autologous neutrophil dependent chemiluminescence.

A rapid (30 min) whole blood assay for the detection of lipopolysaccharide (LPS) is described. This chemiluminescent (CL) assay utilizes the CR1 and CR3 receptor-induced oxidant production of polymorphonuclear leucocytes as a detection platform. The differential priming of neutrophils in whole blood by LPS-antibody complexes allows the specificity of the assay to be achieved. Oxidant released in response to complement opsonized zymosan results in luminol oxidation and subsequent light emission. This is dependent on heat labile putative complement proteins in the plasma. The assay consists of a control which measures baseline whole blood neutrophil oxidant production. The test assay contains murine monoclonal IgM antibody against the Lipid A epitope of LPS and measures the enhanced chemiluminescent response of the neutrophils in the presence of LPS-antibody complexes. Maximal sensitivity of the CL assay is dependent upon optimal antigen-antibody equivalence and duration of pre-incubation with the whole blood sample. The quantification of LPS is possible by inclusion of a positive control containing a maximally reactive LPS dose (800 pg/ml Escherichia coli 055:B5 LPS at an antibody concentration of 0.8 microg/assay). The CL assay is insensitive to variations in patient neutrophil concentration over a minimum range of 0.5 to 20 x 10(9) cells/l. The CL assay is widely reactive with the LPS of many strains of gram negative bacteria but not with the cell wall products of gram positive bacteria or Candida and Aspergillus. In comparison to acid extraction chromogenic LAL, the CL assay demonstrates superior recovery precision and accuracy in in vitro studies. This was reproducible over a wide range of LPS concentrations (0.017-1.6 EU/ml or 20-2000 pg/ml). This assay may be a clinically useful tool for the diagnosis of infection or endotoxin in patients.

Antibodies, Bacterial↗
PubMed1998

The impact of multiple organ dysfunction on mortality following ruptured abdominal aortic aneurysm repair.

The in-hospital mortality for a patient with a ruptured abdominal aortic aneurysm (RAAA) ranges from 30% to 70% and remains unchanged despite aggressive surgical, anesthetic, and intensive-care management. The purpose of this investigation is to determine the relationship between the development of organ dysfunction and mortality in ruptured AAA patients. Eighty-eight consecutive patients admitted to the Toronto Hospital for repair of RAAAs were studied. APACHE II and multiple organ dysfunction (MOD) scores were calculated for all patients. The MOD scoring system measures daily alterations in the function of six key organs, with increased dysfunction indicated by an increasing score. The overall 30-day mortality rate was 40%; 10% of patient deaths occurred intraoperatively. ICU mortality was bimodal; 11.5% deaths occurred within the first 48 hours compared to 18.2% after 48 hours (late deaths). The APACHE II score was significantly higher in those who died within 48 hours of ICU admission (28.5 +/- 6.36) compared to both those who died late (17.2 +/- 5.7, p < 0.0001) and survivors (11.2 +/- 4.2, p < 0.0001). The survivors' daily mean MOD scores did not increase significantly, while the MOD scores for late deaths increased progressively (p < 0.01). The renal and hepatic dysfunction components of the MOD score were significantly lower in the survivors compared to late deaths (p < 0.001), however the respiratory MOD score did not differ between the groups (p > 0.05). The change in MOD (delta MOD) score over the intensive care stay was significantly greater in late deaths compared to survivors (p < 0.01). The rates of infection were similar in both groups and were not responsible for mortality. We conclude that mortality is better predicted following RAAA by the development of renal and hepatic dysfunction rather than by initial physiologic derangement measured by the APACHE II score.

APACHE↗
PubMed1998

Nuclear magnetic resonance evidence of different muscular adaptations after resistance training.

OBJECTIVE: To evaluate muscle bioenergetics, muscle cross-sectional area (CSA), and soreness when the gastrocnemius was subjected to concentric and concentric/eccentric resistance training modes. DESIGN: Prospective study, before and after training. The subjects served as their own controls. SETTING: Rehabilitation center and nuclear magnetic resonance spectroscopy unit of a university hospital. PARTICIPANTS: Sixteen healthy young volunteers from the local physiotherapist school. INTERVENTION: Two distinct resistive training programs were evaluated on the gastrocnemius: a protocol consisting of concentric contractions only and a mixed concentric/eccentric program. MAIN OUTCOME MEASURES: Maximal isometric resistance was measured after each training session. Before and after training, muscle CSA was appreciated using magnetic resonance imaging, whereas changes in muscle pH, phosphorus metabolite ratios, maximal oxidative power (Pmax), and oxidative phosphorylation were studied using 31P nuclear magnetic resonance spectroscopy at rest and during an incremental exercise protocol. RESULTS: Magnetic resonance imaging revealed a significant increase (7.1%) in the gastrocnemius CSA in the concentric-eccentric group only. The PCr/Pi (8.3 +/- 0.9 vs 10.4 +/- 1.7) and PCr/ATP (3.68 +/- .36 vs 4.07 +/- .27) resting ratios increased significantly (p = .008) after concentric-eccentric resistance training. Pmax was significantly improved in the concentric-eccentric group (7.0 +/- 2.1W vs 8.4 +/- 1.8W: p < .02). This mixed protocol also reduced the incidence of muscular soreness. CONCLUSION: The data suggest that the improved oxidative mechanical power output could be due mainly to a greater muscle cross-section in the concentric-eccentric group, with circumstantial evidence suggesting a relatively higher type IIa fiber activity.

Adult↗
PubMed1998

Epidural bupivacaine-morphine analgesia versus patient-controlled analgesia following abdominal aortic surgery: analgesic, respiratory, and myocardial effects.

BACKGROUND: The efficacy and effects of epidural analgesia compared with patient-controlled analgesia (PCA) have not been reported in patients undergoing major vascular surgery. We compared the effects of epidural bupivacaine-morphine with those of intravenous PCA morphine after elective infrarenal aortic surgery. METHODS: Forty patients classified as American Society of Anesthesiologists physical status 2 or 3 received general anesthesia plus postoperative PCA using morphine sulfate (group PCA; n = 21) or general anesthesia plus perioperative epidural morphine-bupivacaine (group EPI; n = 19) during a period of 48 h. During operation, EPI patients received 0.05 mg/kg epidural morphine and 5 ml 0.25% bupivacaine followed by an infusion of 0.125% bupivacaine with 0.1% morphine (0.1 mg/ ml); group PCA received 0.1 mg/kg intravenous morphine sulfate. Continuous electrocardiographic monitoring (V4 and V5 leads) was performed from the night before surgery until 48 h afterward. Respiratory inductive plethysmographic data were recorded after tracheal extubation. Visual analog pain scores at rest and after movement were performed every 4 h after extubation. RESULTS: Nurse-administered intravenous morphine and time to tracheal extubation were less in group EPI, as were visual analog pain scores at rest and after movement from 20 to 48 h. Complications and the duration of intensive care unit and hospital stay were comparable. There was a similar, low incidence of postoperative apneas, slow respiratory rates, desaturation, and S-T segment depression. CONCLUSIONS: Epidural morphine-bupivacaine is associated with reduced early postoperative intravenous opioid requirements, more rapid tracheal extubation, and superior analgesia after abdominal aortic surgery, with comparable respiratory effects.

Aged↗
PubMed1998

Current indications for carotid endarterectomy.

Randomized, prospective trials examining the effectiveness of carotid endarterectomy have given distinct information into the mechanisms and prevention of embolic strokes. The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Atherosclerosis Study (ACAS) have demonstrated the benefits of carotid endarterectomy for patients who meet the precise selection criteria and are treated according to established study protocols. The existing challenge to clinicians lies in the application of trial results to the individual patient.

Carotid Stenosis↗