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D R Anderson

Publications and source records attributed to D R Anderson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Subcutaneous heparin versus low-molecular-weight heparin as thromboprophylaxis in patients undergoing colorectal surgery: results of the canadian colorectal DVT prophylaxis trial: a randomized, double-blind trial.

OBJECTIVE: To compare the effectiveness and safety of low-dose unfractionated heparin and a low-molecular-weight heparin as prophylaxis against venous thromboembolism after colorectal surgery. METHODS: In a multicenter, double-blind trial, patients undergoing resection of part or all of the colon or rectum were randomized to receive, by subcutaneous injection, either calcium heparin 5,000 units every 8 hours or enoxaparin 40 mg once daily (plus two additional saline injections). Deep vein thrombosis was assessed by routine bilateral contrast venography performed between postoperative day 5 and 9, or earlier if clinically suspected. RESULTS: Nine hundred thirty-six randomized patients completed the protocol and had an adequate outcome assessment. The venous thromboembolism rates were the same in both groups. There were no deaths from pulmonary embolism or bleeding complications. Although the proportion of all bleeding events in the enoxaparin group was significantly greater than in the low-dose heparin group, the rates of major bleeding and reoperation for bleeding were not significantly different. CONCLUSIONS: Both heparin 5,000 units subcutaneously every 8 hours and enoxaparin 40 mg subcutaneously once daily provide highly effective and safe prophylaxis for patients undergoing colorectal surgery. However, given the current differences in cost, prophylaxis with low-dose heparin remains the preferred method at present.

Anticoagulants↗
PubMed2001

Early childhood television viewing and adolescent behavior: the recontact study.

In this Monograph, we report the follow-up of 570 adolescents who had been studied as preschoolers in one of two separate investigations of television use. The primary goal of the study was to determine the long-term relations between preschool television viewing and adolescent achievement, behavior, and attitudes. Using a telephone interview and high school transcripts, we assessed adolescent media use; grades in English, science, and math; leisure reading; creativity; aggression; participation in extracurricular activities; use of alcohol and cigarettes; and self-image. In each domain, we tested theories emphasizing the causal role of television content (e.g., social learning, information processing) as contrasted with those theories positing effects of television as a medium, irrespective of content (e.g., time displacement, pacing, interference with language). The results provided much stronger support for content-based hypotheses than for theories emphasizing television as a medium; moreover, the patterns differed for boys and girls. Viewing educational programs as preschoolers was associated with higher grades, reading more books, placing more value on achievement, greater creativity, and less aggression. These associations were more consistent for boys than for girls. By contrast, the girls who were more frequent preschool viewers of violent programs had lower grades than those who were infrequent viewers. These associations held true after taking into account family background, other categories of preschool viewing, and adolescent media use. One hypothesis accounting for the sex differences is that early experiences, such as television viewing, have greater effects when they counteract normative developmental trends and predominant sex-typed socialization influences than when they reinforce them. Adolescents in the study used both television and print media to support ongoing interests. Television content (e.g., entertainment, sports, or world events) predicted extracurricular activities, role models, and body image. The only evidence for possible effects of television as a medium was the positive relation of total viewing to obesity for girls. The medium of television is not homogeneous or monolithic, and content viewed is more important than raw amount. The medium is not the message: The message is.

Adolescent↗
PubMed2000

Treatment of sulfur mustard (HD)-induced lung injury.

An in vivo sulfur mustard (HD) vapor exposure model followed by bronchoalveolar lavage was developed previously in this laboratory to study biochemical indicators of HD-induced lung injury. This model was used to test two treatment compounds--niacinamide (NIA) and N-acetyl cysteine (NAC)--for their ability to ameliorate HD-induced biochemical changes. Anesthetized rats were intratracheally intubated and exposed to 0.35 mg of HD in 0.1 ml of ethanol or ethanol alone for 50 min. At the beginning of the exposure (t = 0), the rats were treated with either NIA (750 mg kg(-1)) or NAC (816 mg kg(-1)), i.p. At 24 h post-exposure, rats were euthanized and the lungs were lavaged with saline (three 5-ml washes). One milliliter of the recovered lavage fluid was analyzed for cellular components. The remaining fluid was centrifuged (10 min at 300 g) and the supernatant was assayed on a Cobas FARA clinical analyzer for lactate dehydrogenase (LDH), gamma-glutamyltransferase (GGT), albumin (ALB), total protein (TP) and glutathione peroxidase (GP). The HD alone and HD+NIA treatment caused significant increases in all of the biochemical parameters compared with control levels. The NAC treatment yielded LDH, ALB and TP values that, although elevated, were not significantly different from the control. The GP levels were significantly higher than the control but significantly lower than the HD alone levels, indicating some protection compared with the HD alone group. The GGT levels were unaffected by NAC compared with HD alone. Cytological analysis of lavage fluid showed that the percentages of neutrophils were 5.3 +/- 1.0 (mean +/- SEM) for control, 46.6 +/- 4.5 for HD, 31.4 +/- 4.7 for HD + NIA and 21.6 +/- 4.7 for HD + NAC, respectively. The neutrophil counts were significantly higher for the three HD-exposed groups vs controls; however, the NAC-treated group had neutrophil counts lower than HD alone, indicating decreased inflammatory response. These results show that NAC may be useful as a potential treatment compound for HD-induced lung injury.

Acetylcysteine↗
PubMed2000

Intervention of sulfur mustard toxicity by downregulation of cell proliferation and metabolic rates.

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chemical warfare compound HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37 degrees C) first in keratinocyte growth medium (KGM) containing BAPTA AM (10-40 microM) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concentration-dependent manner with some cellular degeneration above 30 microM (light microscopy). At 20-30 microM, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 54 +/- 5%), [3H]-uridine (RNA synthesis, 29 +/- 6%) and [14C]-valine (protein synthesis, 12 +/- 2%) as well as a lower protein content per culture (30 +/- 3%) compared with corresponding untreated controls. However, 20-30 microM BAPTA AM did not cause any demonstrable cytopathology based on morphological (electron microscopy) as well as biochemical (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

Cell Culture Techniques↗
PubMed2000

Management of patients with suspected deep vein thrombosis in the emergency department: combining use of a clinical diagnosis model with D-dimer testing.

The management of patients presenting to hospital Emergency Departments with suspected deep vein thrombosis is problematic since urgent diagnostic imaging is at times unavailable. We evaluated the accuracy of a rapidly available D-dimer test and the potential of combining D-dimer testing with an explicit clinical model to improve the management of patients with suspected deep vein thrombosis. Two hundred and fourteen patients with suspected deep vein thrombosis presenting to the Emergency Departments of two tertiary care institutions were enrolled in this prospective cohort study. Patients were evaluated by an Emergency Physician who determined the pre-test probability for deep vein thrombosis to be either low, moderate, or high using an explicit clinical model. Patients were managed according to their pre-test probability category by specific algorithms that in all cases included venous ultrasound imaging within 24 h and a 90-day follow-up for the development of thromboembolic complications. Patients also underwent fingerstick SimpliRED(R) whole blood agglutination D-dimer testing; however, D-dimer results did not influence subsequent patient management. D-dimer had a sensitivity of 82.5% and a specificity of 84.9% for the diagnosis of deep vein thrombosis. The observed negative predictive value of D-dimer was 96.9% (95% CI, 93.0% to 99.1%) overall, and 100% (95% CI, 96.3% to 100%) in low probability patients, 94.1% (95% CI, 83.8% to 98.8%) in moderate probability patients, and 86.7% (95% CI, 59.4% to 98.3%) in high probability patients. SimpliRED(R) D-dimer has a high negative predictive value and may be useful in excluding the diagnosis in patients at low pre-test probability for deep vein thrombosis.

Agglutination Tests↗
PubMed2000

Dynamic thermodynamic resolution: control of enantioselectivity through diastereomeric equilibration.

A theoretical foundation, tools for recognition and control, and recent examples of a class of asymmetric transformation termed dynamic thermodynamic resolution are presented. Enantioselective reaction pathways that involve an induced diastereomeric equilibration to intermediates, which are configurationally stable on the time scale of a subsequent reaction, are illustrated. Dynamic thermodynamic resolution differs from the classic, well-documented pathways of kinetic resolution and dynamic kinetic resolution in that equilibration and resolution can be operative on one system in separate controllable steps. This approach offers a high level of flexibility and provides multiple opportunities for optimization of enantioselectivity.

Stereoisomerism↗
PubMed2000

Evaluation of polyethylene terephthalate for ABO and Rh typing and alloantibody screening.

BACKGROUND: For many years, hospitals and laboratories have used evacuated glass tubes for blood collection. To improve the safety of blood collection, plastic polyethylene terephthalate (PET) tubes (Vacutainer PLUS, Becton Dickinson) have been developed. The objectives of this study were to compare the accuracy of ABO grouping, Rh typing, and antibody screening of blood samples collected in plastic tubes with that in glass tubes and to determine if refrigerated blood samples collected in plastic tubes remained stable over a 28-day period. STUDY DESIGN AND METHODS: Samples were collected from 121 volunteers, at least 30 from each of the A, B, O, and AB blood groups, in four types of Vacutainer tubes: silica-coated plastic, K(2) EDTA plastic, uncoated glass, and K(2) EDTA glass. Samples from each tube were tested for ABO group and Rh type by use of the microtyping gel identification card system and the tube method. A three-cell antibody screen was performed by the microtyping gel card technique with a monospecific IgG reagent. Initial samples were tested within 3 hours of collection. Refrigerated samples were retested for ABO and Rh type and antibody screening 1, 2, 21, and 28 days later. Agreement between test results was determined by using Cohen's Kappa statistic. RESULTS: Complete agreement was observed between the ABO and Rh typing results in samples drawn into glass and plastic tubes of both the EDTA and nonanticoagulated type (kappa = 1.0). In retesting, there were no examples of a change in ABO or Rh type over the 28-day study period. Only two alloantibodies (1.7%) were identified in the 121 samples, and no difference was observed in alloantibody expression in either plastic or glass Vacutainer tubes over the 28-day study period. CONCLUSION: Samples collected into the PET serum or EDTA tubes provided accurate ABO and Rh typing results that remained consistent over a 28-day period. Samples collected in these tubes also appeared to enable accurate alloantibody identification. However, the number of alloantibodies identified in this study was small, and this result should be confirmed in a larger series.

ABO Blood-Group System↗
PubMed2000

Assessment of deep vein thrombosis or pulmonary embolism by the combined use of clinical model and noninvasive diagnostic tests.

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are relatively common diseases and are amenable to therapy but with a potentially fatal outcome if untreated. The diagnosis can be made in most patients with use of the noninvasive imaging tests, but limitations exist. The standard first choice of investigation in patients with suspected DVT is compression ultrasonography (CUS). As with all tests, there is a potential for false-positive and false-negative results. The latter are especially an issue for calf vein thrombi, and this in part has led to the concept of serial CUS testing of the proximal venous system and not imaging of the calf. The premise of the repeat (serial) CUS test is that only thrombi that extend to the proximal system are clinically relevant, and these thrombi will be detected during subsequent testing. However, despite the safety of the serial CUS testing concept, it is inconvenient and expensive. The standard first choice of investigation in patients with suspected PE, the ventilation-perfusion (V/Q) lung scan is nondiagnostic in most cases. In the past few years, the diagnostic process has improved because of the validation of clinical models that accurately categorize patients as having low (5%), moderate (20% to 30%), or high probability (>60%) for venous thromboembolic disease. Among the improvements this provides is the elimination of serial CUS testing if the ultrasound results are normal and the clinical probability is low in patients with suspected DVT. In patients with suspected PE in whom further testing is necessary, determination of clinical probability allows selection of invasive (angiography) or noninvasive testing (serial ultrasound) in patients with non-high-probability V/Q scans. The fibrin degradation product D-dimer has had a high negative predictive value; negative results with enzyme-linked immunosorbent assay (ELISA) tests effectively rule out DVT or PE. In addition, a negative result with less-sentive D-dimer testing and a low clinical probability excludes DVT or PE.

Algorithms↗
PubMed2000

D-dimer for the diagnosis of venous thromboembolism.

D-dimer, a breakdown product of cross-linked fibrin has been extensively evaluated as a diagnostic test for acute venous thromboembolism. Rapid, highly sensitive D-dimer assays are now available that are suitable for testing in the emergency setting. Preliminary studies suggest that when using a highly sensitive D-dimer assay, a negative test result may,be sufficient to exclude the diagnosis of venous thromboembolism without need for further testing. Less sensitive, but more specific D-dimer assays are also available. The negative predictive value of these latter assays is insufficient to exclude venous thromboembolism on the basis of a negative test result alone. However, their utility is increased by identifying patient populations at low risk for venous thromboembolism using consideration of clinical probability or radiographic testing. Further, large multicenter management studies are required to confirm the safety of relying on a negative D-dimer result to exclude the diagnosis of venous thromboembolism.

Antifibrinolytic Agents↗
PubMed2000

Diagnosis of deep-vein thrombosis in the year 2000.

Deep-vein thrombosis is a relatively common disease, amenable to therapy but with a potentially fatal outcome if untreated. The diagnosis can be made in most patients with the noninvasive imaging procedure ultrasonography, but limitations exist. As with all tests, there is a potential for false-positive and false-negative results. The latter are especially an issue for calf vein thrombi, and this in part has led to the concept of serial testing of the proximal venous system and not imaging the calf. The premise of the repeat (serial) test is that only thrombi that extend to the proximal system are clinically relevant and such thrombi will be detected on the repeat test. However, despite the safety of the serial testing concept, it is inconvenient and expensive. In the last few years, the diagnostic process has been improved by the validation of a clinical model that accurately categorizes patients as having low, moderate, or high probability. Among the improvements this provides is the elimination of serial testing if the ultrasonogram is normal and the clinical probability low. The fibrin degradation product D-dimer has been demonstrated to have a high negative predictive value and has also proven useful in diagnostic algorithms. The combination of the D-dimer with clinical model assessment will enable diagnostic testing strategies that are more safe, effective, and convenient for patients.

Agglutination Tests↗
PubMed2000

Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer.

We have previously demonstrated that a clinical model can be safely used in a management strategy in patients with suspected pulmonary embolism (PE). We sought to simplify the clinical model and determine a scoring system, that when combined with D-dimer results, would safely exclude PE without the need for other tests, in a large proportion of patients. We used a randomly selected sample of 80% of the patients that participated in a prospective cohort study of patients with suspected PE to perform a logistic regression analysis on 40 clinical variables to create a simple clinical prediction rule. Cut points on the new rule were determined to create two scoring systems. In the first scoring system patients were classified as having low, moderate and high probability of PE with the proportions being similar to those determined in our original study. The second system was designed to create two categories, PE likely and unlikely. The goal in the latter was that PE unlikely patients with a negative D-dimer result would have PE in less than 2% of cases. The proportion of patients with PE in each category was determined overall and according to a positive or negative SimpliRED D-dimer result. After these determinations we applied the models to the remaining 20% of patients as a validation of the results. The following seven variables and assigned scores (in brackets) were included in the clinical prediction rule: Clinical symptoms of DVT (3.0), no alternative diagnosis (3.0), heart rate >100 (1.5), immobilization or surgery in the previous four weeks (1.5), previous DVT/PE (1.5), hemoptysis (1.0) and malignancy (1.0). Patients were considered low probability if the score was <2.0, moderate of the score was 2.0 to 6.0 and high if the score was over 6.0. Pulmonary embolism unlikely was assigned to patients with scores < or =4.0 and PE likely if the score was >4.0. 7.8% of patients with scores of less than or equal to 4 had PE but if the D-dimer was negative in these patients the rate of PE was only 2.2% (95% CI = 1.0% to 4.0%) in the derivation set and 1.7% in the validation set. Importantly this combination occurred in 46% of our study patients. A score of <2.0 and a negative D-dimer results in a PE rate of 1.5% (95% CI = 0.4% to 3.7%) in the derivation set and 2.7% (95% CI = 0.3% to 9.0%) in the validation set and only occurred in 29% of patients. The combination of a score < or =4.0 by our simple clinical prediction rule and a negative SimpliRED D-Dimer result may safely exclude PE in a large proportion of patients with suspected PE.

Algorithms↗
PubMed2000

Validation of a staging system for evaluating prognosis in prostate cancer.

BACKGROUND: The purposes of our research were to validate a previously published clinical-anatomic staging system for evaluating prognosis in prostate cancer and to explore the predictive ability of additional factors. METHODS: All patients diagnosed with prostate cancer by physicians affiliated with Yale-New Haven Hospital during 1991 were eligible for the study. Patient and tumor characteristics at baseline were extracted from medical records with up to five-year follow-up for mortality. The original system was validated using Cox proportional hazards analysis and conjunctive consolidation. Prostate specific antigen (PSA) and Gleason score were also explored as factors to be included in an updated staging system. RESULTS: Five-year survival was 76% among 121 patients included in the study. The original staging system, when applied to the current cohort, was validated: Five-year survival ranged from 100% (low-risk) to 27% (high-risk). PSA and Gleason score were associated with survival but did not change results substantially in this population. CONCLUSION: By predicting distinct mortality outcomes in men with prostate cancer, prognostic staging systems can be used to help patients and physicians make informed treatment decisions.

Adult↗
PubMed1999

A comparison of three months of anticoagulation with extended anticoagulation for a first episode of idiopathic venous thromboembolism.

BACKGROUND: Patients who have a first episode of venous thromboembolism in the absence of known risk factors for thrombosis (idiopathic thrombosis) are often treated with anticoagulant therapy for three months. Such patients may benefit from longer treatment, however, because they appear to have an increased risk of recurrence after anticoagulant therapy is stopped. METHODS: In this double-blind study, we randomly assigned patients who had completed 3 months of anticoagulant therapy for a first episode of idiopathic venous thromboembolism to continue receiving warfarin, with the dose adjusted to achieve an international normalized ratio of 2.0 to 3.0, or to receive placebo for a further 24 months. Our goal was to determine the effects of extended anticoagulant therapy on rates of recurrent symptomatic venous thromboembolism and bleeding. RESULTS: A prespecified interim analysis of efficacy led to the early termination of the trial after 162 patients had been enrolled and followed for an average of 10 months. Of 83 patients assigned to continue to receive placebo, 17 had a recurrent episode of venous thromboembolism (27.4 percent per patient-year), as compared with 1 of 79 patients assigned to receive warfarin (1.3 percent per patient-year, P<0.001). Warfarin resulted in a 95 percent reduction in the risk of recurrent venous thromboembolism (95 percent confidence interval, 63 to 99 percent). Three patients assigned to the warfarin group had nonfatal major bleeding (two had gastrointestinal bleeding and one genitourinary bleeding), as compared with none of those assigned to the placebo group (3.8 vs. 0 percent per patient-year, P=0.09). CONCLUSIONS: Patients with a first episode of idiopathic venous thromboembolism should be treated with anticoagulant agents for longer than three months.

Anticoagulants↗
PubMed1999

Thrombosis in the emergency department: use of a clinical diagnosis model to safely avoid the need for urgent radiological investigation.

CONTEXT: The management of patients presenting to hospital emergency departments with suspected deep vein thrombosis (DVT) is problematic because urgent diagnostic imaging capability is sometimes unavailable. Experienced physicians using clinical skills alone can classify patients with suspected DVT into low-, moderate-, and high-probability categories. OBJECTIVES: To determine the accuracy of an explicit clinical model for the diagnosis of DVT when applied by emergency department physicians and to assess the safety and feasibility of a management strategy based on the clinical pretest probability for patients presenting to the emergency department with suspected DVT outside of regular hospital staff work hours. METHODS: A prospective cohort study was performed in the emergency departments of 2 tertiary care institutions involving 344 patients with suspected DVT. Patient conditions were evaluated by an emergency department physician who determined the pretest probability for DVT to be low, moderate, or high using an explicit clinical model. Patients for whom DVT was considered a low pretest probability were discharged from the emergency department and returned the following day for venous compression ultrasound imaging of the affected leg. Patients for whom DVT was considered a moderate pre-test probability received a single, weight-adjusted dose of subcutaneous unfractionated heparin sodium (between 12 500 and 20 000 U), were discharged from the emergency department, and returned the next morning to undergo ultrasonography. Patients for whom DVT was considered a high pretest probability were admitted to the hospital, administered intravenous unfractionated heparin, and ultrasonography was arranged within 24 hours. Patients with positive ultrasonographic findings were diagnosed with DVT, except for those with low pretest probability for whom confirmatory venography was performed. Patients with DVT excluded in the initial evaluation period did not receive anticoagulant therapy. All patients were followed up for 90 days to monitor development of thromboembolic or bleeding complications. RESULTS: Twenty-four (49.0% [95% confidence interval (CI), 34.5%-63.6%]) of 49 patients in the high-probability category, 15 (14.3% [95% CI, 8.3%-22.4%]) of 105 in the moderate-, and 6 (3.2% [95% CI, 1.2%-6.7%]) of 190 in the low-probability category were confirmed to have DVT. Overall, 45 (13.1%) of 344 patients were confirmed to have DVT. No patient developed pulmonary embolism or major bleeding complications within 48 hours of initial evaluation in the emergency department. Of the 301 patients who had DVT excluded during the initial evaluation period, only 2 (0.7% [95% CI, 0.1%-2.3%]) developed venous thromboembolic complications (calf vein thromboses in both) in the 3-month follow-up period. CONCLUSIONS: Using an explicit clinical model, emergency department physicians can accurately classify patients with suspected DVT into high-, moderate-, and low-probability groups. A management plan based on probability for DVT that avoids the need for urgent diagnostic imaging is safe and feasible in the emergency department setting.

Decision Trees↗
PubMed1999

Treatment of Guillain-Barré syndrome: a cost-effectiveness analysis.

Acute Guillain-Barré syndrome is the most common cause of neuromuscular paralysis. Plasma exchange and intravenous immune globulin (IV IgG) are both effective treatments for this condition and the purpose of this report was to compare the cost-effectiveness of these two modalities. A MEDLINE search was performed to identify randomized studies that compared the use of IV IgG and plasma exchange for treatment of acute Guillain-Barré syndrome to determine if one modality was more effective and/or safer for the management of this condition. A decision analysis was structured around the alternatives facing neurologists who must choose a treatment regimen for patients diagnosed with acute Guillain-Barré syndrome who require active therapy. Cost information was obtained directly from product manufacturers and hospital sources. Two head-to-head trials comparing the effectiveness of plasma exchange and IV IgG for treatment of acute Guillain-Barré syndrome determined that there was insufficient evidence to suggest one therapy was more effective than the other; therefore, a cost minimization analysis was performed. The costs per patient of plasma exchange and IV IgG for the treatment of acute Guillain-Barré syndrome were $6,204 and $10,165, respectively. A sensitivity analysis determined the model was sensitive to the cost of IV IgG. The cost savings per patient treatment for the use of plasma exchange varied from $304 to $6,625 depending on the IV IgG product selected. Plasma exchange and IV IgG are both effective treatments for Guillain-Barré syndrome. However, our analysis determined plasma exchange on average was almost $4,000 less costly per patient than IV IgG. Further research is required to determine the impact of patient and physician preferences on the treatment of this disorder.

Canada↗