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Biomedical subjects

S L Wheeler

Publications and source records attributed to S L Wheeler.

At least 19 recordsLinked to original sources
PubMed2001

Transfusion practice in elective orthopaedic surgery.

. The transfusion requirements of 2233 patients who underwent total hip or knee joint arthroplasty procedures at nine Canadian hospitals during 1995-1996 were evaluated. Although 64% of patients were eligible for participation in an autologous blood donation (ABD) programme, only 8% predonated blood. Patients who were eligible for ABD were younger (62 years vs. 70 years) and had fewer medical illnesses (18% vs. 44%) than those who did not predonate. The rate of allogeneic transfusion was 9.0% (95% confidence interval 4.9-13.1%) in patients who predonated as compared with 24.1% (95% confidence interval 22.2-25.9%) in those who did not. Risk factors for the occurrence of an allogeneic transfusion were type of procedure (primary or revision hip arthroplasty), lower baseline haemoglobin, lower body weight, older age and presence of rheumatoid arthritis (P < 0.001). Only patients without risk factors were predicted to have a less than 10% risk of receiving an allogeneic transfusion. Use of preventive strategies was minimal. Two models designed to predict the occurrence of an allogeneic transfusion were evaluated. If allogeneic transfusion rates are to be reduced, eligible patients should be encouraged to participate in ABD programmes. For patients who are ineligible, other preventative strategies should be introduced.

Aged↗
PubMed2001

Efficient incorporation of large (>2 kb) heterologies into heteroduplex DNA: Pms1/Msh2-dependent and -independent large loop mismatch repair in Saccharomyces cerevisiae.

DNA double-strand break (DSB) repair in yeast is effected primarily by gene conversion. Conversion can conceivably result from gap repair or from mismatch repair of heteroduplex DNA (hDNA) in recombination intermediates. Mismatch repair is normally very efficient, but unrepaired mismatches segregate in the next cell division, producing sectored colonies. Conversion of small heterologies (single-base differences or insertions <15 bp) in meiosis and mitosis involves mismatch repair of hDNA. The repair of larger loop mismatches in plasmid substrates or arising by replication slippage is inefficient and/or independent of Pms1p/Msh2p-dependent mismatch repair. However, large insertions convert readily (without sectoring) during meiotic recombination, raising the question of whether large insertions convert by repair of large loop mismatches or by gap repair. We show that insertions of 2.2 and 2.6 kbp convert efficiently during DSB-induced mitotic recombination, primarily by Msh2p- and Pms1p-dependent repair of large loop mismatches. These results support models in which Rad51p readily incorporates large heterologies into hDNA. We also show that large heterologies convert more frequently than small heterologies located the same distance from an initiating DSB and propose that this reflects Msh2-independent large loop-specific mismatch repair biased toward loop loss.

Base Pair Mismatch↗
PubMed2001

Tissue preservation for single-tooth anterior esthetics.

Placing implants in the esthetic zone can be difficult because of the expectations of the patient. Inevitably, the hard and soft tissue architecture is lost after extraction in the traditional two-stage procedure, and additional surgical procedures are required to restore the tissue that has been lost. The authors describe techniques that can be applied to retain ideal soft tissue if it is present and predictably restore tissue that is less than ideal.

Adolescent↗
PubMed2000

Erythropoietin with iron supplementation to prevent allogeneic blood transfusion in total hip joint arthroplasty. A randomized, controlled trial.

BACKGROUND: The optimum regimen of epoetin alfa for prevention of allogeneic blood transfusion is unknown. OBJECTIVE: To determine whether a modified regimen of epoetin alfa reduces allogeneic blood transfusion in patients undergoing hip arthroplasty. DESIGN: Randomized, double-blind, multicenter trial comparing two modified dose regimens of epoetin alfa with placebo. SETTING: 13 teaching hospitals and 4 community hospitals in Canada. PATIENTS: 201 patients undergoing primary hip arthroplasty who had a hemoglobin concentration of 98 to 137 g/L and did not predonate blood. INTERVENTION: Patients were assigned in a 3:5:5 ratio to receive four weekly doses of epoetin alfa, 40 000 U (high-dose; n = 44) or 20 000 U (low-dose; n = 79), or placebo (n = 78), starting 4 weeks before surgery. All patients received oral iron supplementation, 450 mg/d, for 42 or more days before surgery. MEASUREMENTS: The primary end point was allogeneic transfusion. Secondary end points were thromboembolic events and change in reticulocyte count and hemoglobin concentration. RESULTS: Both modified epoetin alfa regimens significantly reduced the need for allogeneic transfusion: Five (11.4%) patients in the high-dose group (P = 0.001) and 18 (22. 8%) patients in the low-dose group (P = 0.003) had transfusion, compared with 35 (44.9%) patients in the placebo group. The hematologic response was substantial in patients who received epoetin alfa. In the high-dose group, low-dose group, and placebo group, the preoperative increase in reticulocyte count was 58.8, 37. 0 and 1.8 x 10(9) cells/L (P < 0.001), respectively, and the increase in hemoglobin concentration was 19.5, 17.2, and 1.2 g/L (P < 0.001). The incidence of thromboembolic events did not differ among groups. CONCLUSIONS: Both modified epoetin alfa regimens were effective compared with placebo in reducing allogeneic transfusion in patients undergoing hip arthroplasty. Patients who received high-dose epoetin alfa had the lowest transfusion rate.

Aged↗
PubMed2000

Predictors of symptom resolution in patients with community-acquired pneumonia.

Previous studies have demonstrated that a substantial number of patients with community-acquired pneumonia (CAP) experienced CAP-related symptoms up to 3 months after the completion of antibiotic treatment. We evaluated the frequency of symptoms in a cohort of 535 patients with CAP who presented to a hospital emergency department and completed symptom questionnaires 2 and 6 weeks after the completion of a course of antibiotic therapy. Six weeks after cessation of antibiotic therapy, 64% of patients still reported > or = 1 CAP-related symptoms. Exploratory analyses were performed to identify potential predictors of complete symptom resolution. Logistic regression analysis identified younger age, absence of asthma or chronic obstructive pulmonary disease, and levofloxacin treatment as predictors of complete symptom resolution (all P < .05). Randomized controlled trials should be performed to evaluate the relative efficacy of different antibiotic therapies on the rate of resolution of symptoms.

Adult↗
PubMed2000

Treatment and outcomes of community-acquired pneumonia at Canadian hospitals.

BACKGROUND: Community-acquired pneumonia is a common disease with a large economic burden. We assessed clinical practices and outcomes among patients with community-acquired pneumonia admitted to Canadian hospitals. METHODS: A total of 20 hospitals (11 teaching and 9 community) participated. Data from the charts of adults admitted during November 1996, January 1997 and March 1997 were reviewed to determine length of stay (LOS), admission to an intensive care unit and 30-day in-hospital mortality. Multivariate analyses examined sources of variability in LOS. The type and duration of antibiotic therapy and the proportion of patients who were treated according to clinical practice guidelines were determined. RESULTS: A total of 858 eligible patients were identified; their mean age was 69.4 (standard deviation 17.7) years. The overall median LOS was 7.0 days (interquartile range [IQR] 4.0-11.0 days); the median LOS ranged from 5.0 to 9.0 days across hospitals (IQR 6.0-7.8 days). Only 22% of the variability in LOS could be explained by known factors (disease severity 12%; presence of chronic obstructive lung disease or bacterial cause for the pneumonia 2%; hospital site 7%). The overall 30-day mortality was 14.1% (95% confidence interval [CI] 11.8%-16.6%); 13.6% of the patients were admitted to an intensive care unit (95% CI 11.4%-16.1%). The median duration of intravenous antibiotic therapy was 5 days (range 3.0-6.5 days across hospitals). Although 79.8% of patients received treatment according to clinical practice guidelines, the rate of compliance with the guidelines ranged from 47.9% to 100% across hospitals. INTERPRETATION: Considerable heterogeneity exists in the management of community-acquired pneumonia at Canadian hospitals, the causes of which are poorly understood.

Adult↗
PubMed2000

A controlled trial of a critical pathway for treatment of community-acquired pneumonia. CAPITAL Study Investigators. Community-Acquired Pneumonia Intervention Trial Assessing Levofloxacin.

CONTEXT: Large variations exist among hospitals in the use of treatment resources for community-acquired pneumonia (CAP). Lack of a common approach to the diagnosis and treatment of CAP has been cited as an explanation for these variations. OBJECTIVE: To determine if use of a critical pathway improves the efficiency of treatment for CAP without compromising the well-being of patients. DESIGN: Multicenter controlled clinical trial with cluster randomization and up to 6 weeks of follow-up. SETTING: Nineteen teaching and community hospitals in Canada. PATIENTS: A total of 1743 patients with CAP presenting to the emergency department at 1 of the participating institutions between January 1 and July 31, 1998. INTERVENTION: Hospitals were assigned to continue conventional management (n = 10) or implement the critical pathway (n = 9), which consisted of a clinical prediction rule to guide the admission decision, levofloxacin therapy, and practice guidelines. MAIN OUTCOME MEASURES: Effectiveness of the critical pathway, as measured by health-related quality of life on the Short-Form 36 Physical Component Summary (SF-36 PCS) scale at 6 weeks; and resource utilization, as measured by the number of bed days per patient managed (BDPM). RESULTS: Quality of life and the occurrence of complications, readmission, and mortality were not different for the 2 strategies; the 1-sided 95% confidence limit of the between-group difference in the SF-36 PCS change score was 2.4 points, which was within a predefined 3-point boundary for equivalence. Pathway use was associated with a 1.7-day reduction in BDPM (4.4 vs 6.1 days; P = .04) and an 18% decrease in the admission of low-risk patients (31% vs 49%; P = .01). Although inpatients at critical pathway hospitals had more severe disease, they required 1.7 fewer days of intravenous therapy (4.6 vs 6.3 days; P = .01) and were more likely to receive treatment with a single class of antibiotic (64% vs 27%; P<.001). CONCLUSION: In this study, implementation of a critical pathway reduced the use of institutional resources without causing adverse effects on the well-being of patients.

Aged↗
PubMed1999

Multiple heterologies increase mitotic double-strand break-induced allelic gene conversion tract lengths in yeast.

Spontaneous and double-strand break (DSB)-induced allelic recombination in yeast was investigated in crosses between ura3 heteroalleles inactivated by an HO site and a +1 frameshift mutation, with flanking markers defining a 3.4-kbp interval. In some crosses, nine additional phenotypically silent RFLP mutations were present at approximately 100-bp intervals. Increasing heterology from 0.2 to 1% in this interval reduced spontaneous, but not DSB-induced, recombination. For DSB-induced events, 75% were continuous tract gene conversions without a crossover in this interval; discontinuous tracts and conversions associated with a crossover each comprised approximately 7% of events, and 10% also converted markers in unbroken alleles. Loss of heterozygosity was seen for all markers centromere distal to the HO site in 50% of products; such loss could reflect gene conversion, break-induced replication, chromosome loss, or G2 crossovers. Using telomere-marked strains we determined that nearly all allelic DSB repair occurs by gene conversion. We further show that most allelic conversion results from mismatch repair of heteroduplex DNA. Interestingly, markers shared between the sparsely and densely marked interval converted at higher rates in the densely marked interval. Thus, the extra markers increased gene conversion tract lengths, which may reflect mismatch repair-induced recombination, or a shift from restoration- to conversion-type repair.

Alleles↗
PubMed1999

Restoration of congenitally missing lateral incisors: a case report.

Parents and dentists are forced to make a decision early in a young patient's life when it is learned that the lateral incisors are missing. For many years the treatment has been to either move the cuspids into the lateral incisor sites or retain the teeth in their natural environment and restore the defect with a bonded or fixed bridge. With the advent of new designs in dental implants and their abutments, it is possible to consider replacing missing single teeth with implant-borne prostheses. Often-times, because of the limited residual bone and proximity of adjacent roots, placing conventional cylinder or screw-type implants is difficult. This article demonstrates the advantages of using a tapered-step implant, immediate one-stage surgery, and temporization in replacing congenitally missing laterals.

Adolescent↗
PubMed1997

Sinus augmentation for dental implants: the use of alloplastic materials.

The ability to augment the sinus floor has dramatically expanded the scope of implant dentistry. Clinical and scientific studies abound as to the efficacy of this procedure. The debate still ensues as to the best material to use for this augmentation, with autogenous bone, freeze-dried bone, xenografts, and alloplasts all being advocated. This article will substantiate through scientific and clinical studies, how the use of allplastic materials in sinus augmentation techniques can greatly reduce the morbidity and the expense of the procedure while predictably producing bone that has been shown to support dental implants in function for extended periods of time.

Alveolar Ridge Augmentation↗
PubMed1993

Energy expenditure in dogs with lymphoma fed two specialized diets.

BACKGROUND: Cancer-caused cachexia has been reported to be caused in part by an increase in energy expenditure, and diets with nutrient profiles containing 30-50% nonprotein calories as fat instead of carbohydrate may exacerbate this state of inefficient energy utilization. METHODS: Indirect calorimetry was performed on 22 dogs with high-grade lymphoblastic lymphoma that were randomized into a blind study and fed isocaloric amounts of a high-fat diet (Diet A) or a high-carbohydrate diet (Diet B) before and after remission was attained with up to five doses of doxorubicin chemotherapy (30 mg/m2 intravenously). Indirect calorimetry was also performed on 30 normal dogs for comparison. RESULTS: During the initial evaluation period, the resting energy expenditure (REE/kg0.75, P < 0.05) and respiratory quotient (RQ, P < 0.05) were significantly lower than in the controls. Six weeks after the start of the study, the REE/kg0.75 and oxygen consumption (VO2/kg0.75) were significantly (P < 0.05) lower in both groups of dogs with lymphoma compared with the controls. The RQ determined 6 weeks after the start of the study for the dogs fed Diet A was significantly (P < 0.05) lower compared with that in the controls evaluated at the same time. When the two groups of dogs with lymphoma were compared with each other, there was no significant difference in any of the outcomes. The REE/kg0.75 and VO2/kg0.75 values were significantly lower (P < 0.05) in the group fed Diet A after the third evaluation period compared with the second evaluation. The REE/kg0.75 and VO2/kg0.75 values were significantly lower (P < 0.05) in the group given Diet B at the fourth evaluation period compared with the fifth. CONCLUSIONS: These data suggest that energy expenditure of dogs with lymphoma decreases transiently in response to chemotherapy and remission, but these values are less than those determined in normal dogs and not altered significantly by diet.

Animals↗
PubMed1993

Success and failure rates of cylinder implants in type IV bone.

It is well documented that implant success rates are much lower in Type IV bone than in Types I, II, and III. However, all of these studies have reported on the use of screw type implants. The present study demonstrates the efficacy of cylinder implant use in Type IV bone. A total of 513 cylinders were placed in Type IV bone and were followed for 0 to 60+ months in function. The absolute success rate was 95.7%. Of the 22 fixture failures encountered, 8 were discovered at the time of second stage surgery, 3 during the first year following uncovering, and 11 occurred after 24 to 36 months in function. A possible rationale for the higher success rate of cylinders as compared to that reported for screw type implants in Type IV bone is presented. Further well-controlled studies directly comparing various implant designs in a range of bony sites are needed to better understand and to fully document the differences suggested by the present study.

Alveolar Bone Loss↗
PubMed1993

The use of IMZ osseointegrated implants in partially and completely edentulous patients: success and failure rates of 2,023 implant cylinders up to 60+ months in function.

A total of 974 patients were treated with 2,023 IMZ implants. A variety of prosthodontic designs were utilized. These included replacement of single teeth, use as pier abutments, and for totally implant-supported prostheses. The implants were followed in function for 6 to 60+ months. Absolute success rates were 96.4% and 98.4% in the maxilla and mandible, respectively. Cumulative success rates at the end of the study were 92.9% and 95.8% in the maxilla and mandible, respectively. The use of an intramobile element is also discussed.

Adolescent↗
PubMed1993

Repeatability of energy expenditure measurements in clinically normal dogs by use of indirect calorimetry.

Energy expenditure (EE) was determined, using an open-flow indirect calorimetry system in a group of 20 clinically normal, apparently resting, client-owned dogs. Five evaluations were performed over an 8-hour period to determine reliability of the method. The intraclass correlation coefficient was calculated as the ratio of within- and between-subject variances, using repeated-measures ANOVA. When only the middle 3 evaluations were included, the intraclass correlation coefficient was 0.87, indicating good reliability. The first evaluation was higher than the subsequent 4 evaluations for rate of O2 consumption (Vo2/kg and Vo2/kg0.75; (P < or = 0.01), and EE/kg and EE/kg0.75 (P < or = 0.005). The respiratory quotients at the first (P = 0.004) and second (P = 0.013) evaluations were different from the respiratory quotient at the fourth evaluation. Therefore, the first evaluation may not be representative of the actual EE. The mean value of at least 3 subsequent evaluations after an adequate adaptation period (5 to 10 minutes) to the equipment will be useful for predicting energy requirements of apparently resting, clinically normal dogs.

Animals↗
PubMed1992

Effects of chemotherapy and remission on carbohydrate metabolism in dogs with lymphoma.

After a 12-hour fast, blood samples were obtained from 27 dogs with previously untreated lymphoma before and 5, 15, 30, 45, and 60 minutes after an intravenous (IV) challenge with 500 mg/kg dextrose. This procedure was done for each dog before up to five treatments with the IV doxorubicin (30 mg/m2 every 3 weeks). All dogs achieved a complete remission. Samples were assayed for glucose, lactate, and insulin concentrations, and results were compared statistically with those from 16 normal control dogs of similar weight and age undergoing an identical dextrose challenge before and 3 weeks after receiving one dose of IV doxorubicin (30 mg/m2). Glucose, lactate, and insulin concentrations did not change significantly in response to glucose challenge in control dogs after doxorubicin chemotherapy. Lactate and insulin concentrations in untreated dogs with lymphoma were significantly higher than controls. This hyperlactatemia and hyperinsulinemia did not improve when dogs with lymphoma were put into remission with doxorubicin chemotherapy. The results indicate that carbohydrate metabolism is altered in dogs with lymphoma, and that these abnormalities do not improve when a complete remission is obtained with doxorubicin chemotherapy.

Animals↗
PubMed1986

Continuous positive airway pressure therapy for aspiration pneumonia in a dog.

A 14-year-old mixed-breed dog aspirated a large amount of liquid barium sulfate. Calculation of the alveolar arterial oxygen tension difference (34 mm of Hg; normal, less than 7.5 mm of Hg) from the alveolar gas equation and the arterial blood gas analysis indicated impaired pulmonary gas exchange. The dog was treated for 5 days with continuous positive airway pressure and supplemental oxygen administered by a simple apparatus connected to a tracheostomy tube. Continuous positive airway pressure was believed to improve gas exchange and to increase pulmonary compliance by decreasing alveolar collapse in this dog.

Animals↗