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Biomedical subjects

K Anderson

Publications and source records attributed to K Anderson.

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

Complications of thermal capsulorrhaphy.

As the popularity of thermal capsular shrinkage continues to increase, analysis of complications and failures will continue to provide helpful information in guiding patient selection and decreasing morbidity. Patients who are undergoing revision surgery or who have a history of multiple preoperative dislocations appear to be at higher risk for failure with thermal shrinkage surgery. Caution should be exercised for patients who participate in contact or collision sports, as well as those with MDI. Further study may determine whether thermal shrinkage is most appropriate for microinstability or used as an adjunct to other stabilization procedures.

Electrocoagulation↗
PubMed2001

Gestational diabetes mellitus: a kitchen table approach.

The issue of gestational diabetes mellitus within disadvantaged communities is being addressed by Healthy Start for Mom & Me, a highly collaborative and multi-faceted prenatal nutrition program targeting at-risk women and teens in Winnipeg, Manitoba. The program s kitchen table approach focuses on the core concepts of education, community participation, and capacity-building to develop effective methods for community-based practice in this population. A qualitative case study of the program was conducted in 1999. This study showed that health education practices in the program are sensitive to marginalized women s needs and enhance service providers understanding of the context of participants lives. Community dietitians roles in this prenatal program are evolving, and are significant for other dietitians charting a new course of community-based practice.

Canada↗
PubMed2000

Vagal immune-to-brain communication: a visceral chemosensory pathway.

The immune system operates as a diffuse sensory system, detecting the presence of specific chemical constituents associated with dangerous micro-organisms, and then signalling the brain. In this way, immunosensation constitutes a chemosensory system. Several submodalities of this sensory system function as pathways conveying immune-related information, and can be classified as either primarily brain barrier associated or neural. The vagus nerve provides the major neural pathway identified to date. The initial chemosensory transduction events occur in immune cells, which respond to specific chemical components expressed by dangerous micro-organisms. These immune chemosensory cells release mediators, such as cytokines, to activate neural elements, including primary afferent neurons of the vagal sensory ganglia. Primary afferent activation initiates local reflexes (e.g. cardiovascular and gastrointestinal) that support host defense. In addition, at least three parallel pathways of ascending immune-related information activate specific components of the illness response. In this way, immunosensory systems represent highly organized and coherent pathways for activating host defense against infection.

Animals↗
PubMed2000

Associations between dietary intake and Ki-ras mutations in colon tumors: a population-based study.

Ki-ras mutations are thought to be early events in the carcinogenic process leading to colon tumors. Dietary factors associated with colon cancer may be associated with these mutations. Data from a population-based, multicenter, case-control study of colon cancer were used to determine whether dietary factors are associated with Ki-ras mutations. Ki-ras mutations were detected by direct sequencing of codons 12 and 13 of the Ki-ras gene on exon 1 from DNA obtained from archival tissue. Ki-ras data were available for 1428 cases with valid interview data; data from 2410 controls were available for comparison with cases positive and negative for Ki-ras mutations. Mutations in the Ki-ras gene were detected in 32% of tumors. Of these mutations, 32.8% were G-->A transitions in the second base of codon 12 (2G-->A). Other than cruciferous vegetables, there were no nutrients or foods associated specifically with Ki-ras mutations [odds ratio (OR) for high intake relative to low intake, 0.7; 95% confidence interval (CI), 0.5-1.0]. However, evaluation of specific types of Ki-ras mutations revealed that for each of the most common types of mutation, dietary associations existed. Dietary factors involved in DNA methylation pathways were associated with 2G-->A mutations. Comparison of individuals with and without Ki-ras mutations revealed that individuals with low levels of dietary folate (OR, 0.7; 95% CI, 0.4-1.3), vitamin B6 (OR, 0.5; 95% CI, 0.3-1.0), vitamin B12 (OR, 0.6; 95% CI, 0.3-1.1), and high levels of alcohol (OR, 0.7; 95% CI, 0.4-1.1) were less likely to have a 2G-->A mutation. Individuals with high levels of dietary carbohydrate (OR, 2.0; 95% CI, 0.9-4.4) and a high glycemic index (OR, 1.9; 95% CI, 0.8-4.6) were more likely to have a G-->A transition mutation in the second base of codon 13 (5G-->A). Individuals with high levels of dietary fat (OR, 1.6; 95% CI, 0.8-3.2), saturated fat (OR, 1.7; 95% CI, 0.8-3.5), and monounsaturated fat (OR, 1.9; 95% CI, 1.0-3.7) were more likely to harbor a 2G-->T mutation. Low levels of cruciferous vegetable intake and high levels of processed meat intake also were associated with fewer 5G-->A, as reflected by the ORs (OR, 0.4; 95% CI, 0.2-1.0 and OR, 0.4; 95% CI 0.2-0.8, respectively). These data suggest that diet may be involved in disease pathways represented by specific Ki-ras mutations. However, given the limited information currently available on associations between specific genetic mutations in colon tumors and diet, these findings also should be viewed as hypothesis generating.

Adult↗
PubMed2000

Associations between cigarette smoking, lifestyle factors, and microsatellite instability in colon tumors.

BACKGROUND: Microsatellite instability (MSI) has been reported to occur in approximately 10%-15% of colon tumors. MSI is characterized by the presence of mutations in tandemly repeated DNA sequences known as microsatellites. Some individuals with unstable tumors have inherited mutations in mismatch repair genes, but MSI is also observed in sporadic colon cancer. It is unknown whether lifestyle factors associated with colon cancer, such as physical activity, body size, cigarette smoking, or use of aspirin and/or nonsteroidal anti-inflammatory drugs, contribute to MSI in sporadic tumors. METHODS: Data from a population-based, case-control study of colon cancer were used. Case subjects were between 30 and 79 years of age at the time of diagnosis and included both men and women. Questionnaire data were used to obtain information on lifestyle factors. Tumor MSI was determined with the use of a panel of 10 tetranucleotide repeats and two mononucleotide repeats. A total of 1510 case subjects had valid questionnaire data and tumor DNA from which we were able to obtain MSI status. Questionnaire data were compared with lifestyle factors reported by 2410 population-based control subjects. All statistical tests were two-sided. RESULTS: MSI-positive (MSI(+)) tumors were most common in older people and women and in the proximal colon. Patients with MSI(+) tumors were more likely to smoke 20 or more cigarettes a day than case subjects with MSI-negative (MSI(-)) tumors (odds ratio for being a smoker = 1.6 [95% confidence interval = 1.0-2.5] for men and 2.2 [95% confidence interval = 1.4-3.5] for women). The association between MSI(+) tumors and cigarette smoking was strongest among case subjects who started to smoke at a young age, smoked for 35 or more years, and were either current smokers or had stopped fewer than 15 years before diagnosis. A statistically significant linear trend of increased risk of MSI(+) tumors was observed with increasing amount smoked (P<.01). CONCLUSIONS: This study suggests that smoking cigarettes statistically significantly contributes to MSI in colon tumors. We estimate that approximately 21% of MSI in colon tumors may be attributable to cigarette smoking.

Adult↗
PubMed2000

Effect of vaccination with 3 recombinant asexual-stage malaria antigens on initial growth rates of Plasmodium falciparum in non-immune volunteers.

A placebo controlled, randomised, double blind trial was conducted in human volunteers to test a mixture of three recombinant Plasmodium falciparum blood stage antigens for its ability to reduce the initial growth rates of parasites. The vaccine contained recombinant MSP2 (3D7 allele), a portion of MSP1 (190LCS.T3) and part of the RESA antigen (C terminal 771 amino acids) in the Montanide ISA 720 adjuvant (SEPPIC). Twelve volunteers received two doses of the vaccine, 6 weeks apart. The five participants in the placebo group received an equivalent volume of the adjuvant emulsion using the same schedule. Antibody responses were low, as has been reported in earlier studies with this combination, while T cell responses were stronger. All the volunteers were challenged with approximately 140 ring infected red cells of the 3D7 cloned line, 4 weeks after the second dose. Parasitaemia was determined once daily from day 4 using a sensitive and quantitative PCR assay. All the volunteers were infected and were treated on day 8, before any developed symptoms. There was no significant difference in initial parasite growth rates between the verum and placebo groups, nor was there any significant correlation between parasite growth rates and any of the measured immunological responses. These results suggest that the formulation tested in this trial did not generate immune responses that were strong enough to reduce parasite growth in naive volunteers.

Adult↗
PubMed2000

Permanent, direct His-bundle pacing: a novel approach to cardiac pacing in patients with normal His-Purkinje activation.

BACKGROUND: Direct His-bundle pacing (DHBP) produces synchronous ventricular depolarization and improved cardiac function relative to apical pacing. Although it has been performed transiently in the electrophysiology laboratory and persistently in open-chested canines, permanent DHBP in humans has not been achieved. METHODS AND RESULTS: A total of 18 patients aged 69+/-10 years who had a history of chronic atrial fibrillation, dilated cardiomyopathy, and normal activation (ie, QRS< or =120 ms) were screened for permanent DHBP using an electrophysiology catheter. In 14 patients, the His bundle could be reliably stimulated. Of these 14, permanent DHBP using a fixed screw-in lead was successful in 12 patients. Radiofrequency atrioventricular node ablation was performed in patients exhibiting a fast ventricular response. All patients received single-chamber rate-responsive pacemakers. Acute pacing thresholds were 2.4+/-1.0 V at a pulse duration of 0.5 ms. Lead complications included exit block requiring reoperative adjustment and gross lead dislodgment. Echocardiographic improvement in heart function was shown by reductions in the left ventricular end-diastolic dimension from 59+/-8 to 52+/-6 mm (P</=0.01) and in the end-systolic dimension from 51+/-10 to 43+/-8 mm (P<0.01), with an accompanying increase in fractional shortening from 14+/-7% to 20+/-10% (P=0.05). The left ventricular ejection fraction improved from 20+/-9% to 31+/-11% (P<0. 01), and the cardiothoracic ratio decreased from 0.61+/-0.06 to 0. 57+/-0.07 (P<0.01). Despite DHBP, 2 patients died at 8 and 36 months. Conclusions-Permanent DHBP is feasible in select patients who have chronic atrial fibrillation and dilated cardiomyopathy. Long-term, DHBP results in a reduction of left ventricular dimensions and improved cardiac function.

Atrial Fibrillation↗
PubMed2000

Abciximab improves both epicardial flow and myocardial reperfusion in ST-elevation myocardial infarction. Observations from the TIMI 14 trial.

BACKGROUND: In the presence of ST-elevation myocardial infarction, patients with successful epicardial reperfusion (TIMI 3 flow) but persistent ST elevation on a 12-lead ECG are at high risk for subsequent death and left ventricular dysfunction. In the TIMI 14 trial, a dose-ranging angiographic study, combined therapy with abciximab plus reduced-dose tPA enhanced the speed and efficacy of epicardial reperfusion. We determined whether the combination of abciximab plus reduced-dose tPA provided additional benefit in terms of myocardial reperfusion, as evidenced by greater resolution of ST elevation. METHODS AND RESULTS: All 346 patients with interpretable baseline and 90-minute ECGs, treated with either tPA alone or abciximab plus reduced-dose tPA (combination therapy), were included. Patients receiving combination therapy (n=221) had a 59% rate of complete (>/=70%) ST resolution at 90 minutes versus 37% in those treated with tPA alone (n=125) (P<0.0001). When the analysis was limited to patients with TIMI 3 flow, patients treated with combination therapy (n=151) remained significantly more likely to achieve complete ST resolution than those receiving tPA alone (n=80) (69% versus 44%; P=0.0002). CONCLUSIONS: Combination therapy with abciximab and reduced-dose tPA improves myocardial (microvascular) reperfusion, as reflected in greater ST-segment resolution, in addition to epicardial flow. This finding may translate into improved clinical outcomes by enhancing myocardial salvage.

Abciximab↗
PubMed2000

Evidence for a linear search in bimolecular 3' splice site AG selection.

In most eukaryotic introns the 3' splice site is defined by a surprisingly short AG consensus found a variable distance downstream of the branch site. Exactly how the spliceosome determines which AG to use, however, is not well understood. Previously we showed that when the branch site and 3' splice site AG are supplied by separate RNA molecules, there is a strong preference for use of the 5'-most AG in the 3' splice site-containing RNA. Here we show that this apparent 5'-->3' directionality holds even when this RNA contains four tandem repeats of a 6-nt sequence containing AG. Exactly the same pattern of 3' splice site choice was observed when the same tandem repeats were incorporated into a full-length splicing substrate. When the 3' splice site AG is supplied by a separate RNA, that RNA must be linear with an unobstructed 5' end. Similarly, the branch-containing RNA must be truncated immediately 3' to the polypyrimidine tract. A model is presented that incorporates these observations and reconciles previously proposed mechanisms for 3' splice site selection.

Adenine Nucleotides↗
PubMed2000

The egg-shell sign: a possible indicator of raised intrarenal pressure.

Prenatal diagnosis of pelvicalyceal dilatation has produced clinical material that we are continually reinterpreting with the help of improving ultrasound equipment. However, the ability to predict the outcome for any one patient with marked dilatation remains poor. We describe a new sign that may help identify those fetuses who have high intrarenal pressure and therefore justify more aggressive management, while obviating the need for intervention for those in whom it is not present. The egg-shell sign consists of a thin crescent of increased echogenicity over a distended calyx and, in this case, was documented to be associated with other features of raised intrarenal pressure.

Adult↗
PubMed2000

Use of archival tissue in epidemiologic studies: collection procedures and assessment of potential sources of bias.

Collection and analyses of archival tumor tissue as a means to increase our understanding of disease pathways is becoming an important avenue of epidemiologic research. In this paper, we present methods of collection and processing of archival tissue and assess the population characteristics of those for whom we were able to and unable to obtain tumor DNA. Cases of colon cancer diagnosed between September, 1991 and October, 1994 living in Utah, Northern California, or the Twin Cities Metropolitan area of Minnesota were targeted for this study. Of the 2477 people for whom we had permission to obtain tumor blocks, we were able to collect blocks and extract DNA for 2117 (85.5%). There were no differences in age, tumor site, or diet and lifestyle characteristics between those with and without DNA extracted. However, we were less likely to be able to extract DNA if the case was diagnosed at a more advanced disease stage or at the earliest disease. Potential bias from exclusion of those with the most advanced disease stage is discussed.

Adult↗
PubMed2000

Bimolecular exon ligation by the human spliceosome bypasses early 3' splice site AG recognition and requires NTP hydrolysis.

Here we report further characterization of an in vitro assay system for exon ligation by the human spliceosome in which the 3' splice site AG is supplied by a different RNA molecule than that containing the 5' splice and branch sites. By varying the time during splicing reactions when the 3' splice site AG is made available to the splicing machinery, we show that AG recognition need not occur until after lariat formation. Thus an early AG recognition event required for spliceosome formation and lariat formation on some mammalian introns is not required for exon ligation. Depletion/add-back studies and cold competitor challenge experiments reveal that commitment of a 3' splice site AG to exon ligation requires NTP hydrolysis. Because it both physically and kinetically uncouples exon ligation from spliceosome assembly and lariat formation, the bimolecular system will be a valuable tool for further mechanistic analysis of the second step of splicing.

Adenosine Triphosphate↗
PubMed2000

Association of mammographically defined percent breast density with epidemiologic risk factors for breast cancer (United States).

OBJECTIVE: Mammographically defined percent breast density is an important risk factor for breast cancer, but the epidemiology of this trait is poorly understood. Although several studies have investigated the associations between reproductive factors and density, few data are available on the associations of breast density and waist-to-hip ratio (WHR), physical activity, education, alcohol and smoking. METHODS: We investigated the associations of known and suspected breast cancer risk factors with breast density in a large breast cancer family study. Information was collected on members of 426 families through telephone interviews, mailed questionnaires and mammography. Mammographic films on 1900 women were digitized and breast density was estimated in discrete five-unit increments by one radiologist. Analysis of covariance techniques were used and all analyses were performed stratified by menopausal status. RESULTS: Similar to other reports, nulliparity, late age at first birth, younger age and lower body mass index were associated with increased percent density in both premenopausal and postmenopausal women, and hormone replacement therapy among postmenopausal women. Higher levels of alcohol consumption and low WHR were associated with increased percent density among both premenopausal and postmenopausal women (differences of 3-11% between high and low categories). However, smoking and education were inversely associated with percent density among premenopausal (p = 0.004 and p = 0.003, respectively) but not postmenopausal women (p = 0.52 and p = 0.90). Physical activity was not associated with percent density in either stratum (p values > 0.25). Combined, these factors explained approximately 37% of the variability in the percent density measure in premenopausal women and 19% in postmenopausal women. CONCLUSIONS: Many of these factors may potentially affect breast cancer risk through their effect on percent breast density.

Adult↗
PubMed2000

Combination reperfusion therapy with abciximab and reduced dose reteplase: results from TIMI 14. The Thrombolysis in Myocardial Infarction (TIMI) 14 Investigators.

Aims Abciximab has previously been shown to enhance thrombolysis and improve myocardial perfusion when combined with reduced doses of alteplase. The purpose of the reteplase phase of TIMI 14 was to evaluate the effects of abciximab when used in combination with a reduced dose of reteplase for ST-elevation myocardial infarction. Methods and Results Patients (n=299) with ST-elevation myocardial infarction were treated with aspirin and randomized to a control arm with standard dose reteplase (10+10 U given 30 min apart) or abciximab (bolus of 0.25 mg. kg(-1)and 12-h infusion of 0.125 microg. kg(-1). min(-1)) in combination with reduced doses of reteplase (5+5 U or 10+5 U). Control patients received standard weight-adjusted heparin (bolus of 70 U. kg(-1); infusion of 15 U. kg(-1). h(-1)), while each of the combination arms with abciximab and reduced dose reteplase received either low dose heparin (bolus of 60 U. kg(-1); infusion of 7 U. kg(-1). h(-1)) or very low dose heparin (bolus of 30 U. kg(-1); infusion of 4 U. kg(-1). h(-1)). The rate of TIMI 3 flow at 90 min was 70% for patients treated with 10+10 U of reteplase alone (n=87), 73% for those treated with 5+5 U of reteplase with abciximab (n=88), and 77% for those treated with 10+5 U of reteplase with abciximab (n=75). Complete (>/=70%) ST resolution at 90 min was seen in 56% of patients receiving a reduced dose of reteplase in combination with abciximab compared with 48% of patients receiving reteplase alone. Conclusions Reduced doses of reteplase when administered in combination with abciximab were associated with higher TIMI 3 flow rates than reported previously for reduced doses of reteplase without abciximab and were at least as high as for full dose reteplase alone

Abciximab↗