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Biomedical subjects

L A Cannon

Publications and source records attributed to L A Cannon.

18 recordsLinked to original sources
PubMed2001

Therapeutic ultrasound for chronic total coronary artery occlusions.

This article focuses on the use of catheter-delivered ultrasound as a device for treatment of coronary arterial total occlusion (CTO). The standard treatment of CTO is reviewed and serves as the basis for the need for new treatment options, such as catheter-delivered ultrasound (SONICROSS). The results of FDA-approved Phase I and Phase II clinical trials using SONICROSS for refractory CTO are described. The Phase II trials indicate that the SONICROSS-facilitated guidewire passage in 71% of CTOs are otherwise refractory to guidewire passage. However, at present, the SONICROSS catheter system is limited in its ability to be delivered reliably to the CTO because of catheter size and trackability.

Clinical Trials, Phase I as Topic↗
PubMed2000

Acute MI. Age-related presentations and treatment options.

At least 60% of all acute myocardial infarctions (AMIs) occur in patients age 65 and older and about one-third in patients older than age 75. The presentation of AMI is modified by age-related changes in endothelial function, smooth muscle cell activity, diastolic function, and responses to circulating catecholamines. Atypical presentations are common in the older patient and require the physician to maintain a high index of suspicion for AMI. ECG findings of ST-segment depression make many older patients ineligible for reperfusion by thrombolytic therapy. Acute and post-MI medical therapies are underused in the older population and should be individualized, based on the presence of comorbid conditions.

Age Factors↗
PubMed1993

Cardiac disease in the elderly population.

Cardiovascular disease is the prime cause of disability and death in the elderly population. This article provides a brief review of cardiac physiology in this group as well as a discussion of the acute presentation of myocardial ischemia and infarction, congestive heart failure, vascular dysfunction, and complications of valve replacement.

Aged↗
PubMed1991

Atrial myxoma associated with inferior myocardial infarction.

Acute myocardial infarction is a rare complication of left atrial myxoma. We report the case of a 44-year-old man who suffered an acute inferior myocardial infarction and systemic embolization to the lower extremities and brain resulting from myxomatous embolization. This diagnosis should be considered in a young person presenting with systemic embolization and acute myocardial infarction.

Adult↗
PubMed1990

The incidence of bacteremia associated with emergent intubation: relevance to prophylaxis against bacterial endocarditis.

STUDY OBJECTIVE: To examine the incidence of bacteremia associated with emergent nasotracheal intubation. STUDY DESIGN: Non-randomized, controlled cohort trial during 30 minutes post-intubation with limited in-hospital follow-up. SETTING: Emergency care unit and inpatient setting of a tertiary care facility. PATIENTS: Emergency care unit patients with acute respiratory distress necessitating non-elective emergency airway placement. MEASUREMENTS AND MAIN RESULTS: We studied 84 blood cultures obtained from 21 patients intubated emergently. Fourteen patients were intubated by the nasotracheal (NT) route and seven patients were intubated orotracheally (OT) for comparison. Pre-intubation and post-intubation blood cultures were obtained at two to five, 10 to 15 and 30 minutes after intubation. Patients were excluded if they had strong clinical evidence of pre-existing bacterial infection, had received antibiotics within 48 hours of presentation or were less than 16 years of age. Of the patients that were NT intubated, 29% (4/14) of patients became bacteremic after intubation. All had negative pre-intubation cultures. Organisms isolated were nasopharyngeal florae and included: Streptococcus viridans, Veillonellae sp., aerobic diphtheroids, and other mouth florae. Of the seven patients with OT intubation, six were culture negative. One was excluded because of positive preintubation cultures secondary to urosepsis. No patients in our study developed complications that could be directly attributed to these organisms or to intubation alone. CONCLUSIONS: The risk of bacteremia associated with emergency nasotracheal intubation is substantial and is accompanied by organisms that may produce serious morbidity in the patient with valvular heart disease or compromised immunity. Our findings suggest that, whenever possible, the nasotracheal route should be avoided for emergency intubation in patients with valvular heart disease and if used, prophylactic antibiotics should be strongly considered.

Aged↗
PubMed1987

Magnesium levels in cardiac arrest victims: relationship between magnesium levels and successful resuscitation.

Multivariate analysis was performed to evaluate significant differences between electrolytes, serum magnesium, and successful resuscitation in cardiac arrest victims in a prospective controlled study. Twenty-two cardiac arrest victims having ventricular fibrillation or tachycardia, electromechanical dissociation, or asystole were compared with 19 matched controls with no ventricular arrhythmias. Of the control group, one was hypermagnesemic (5%), 17 normomagnesemic (90%), and one hypomagnesemic (5%). In the arrest group, eight were hypermagnesemic (36%), nine normomagnesemic (41%), and five hypomagnesemic (23%). Thirteen of 22 cardiac arrest victims (59%) had an abnormal serum magnesium level. All hypermagnesemic and hypomagnesemic patients expired (100%). In the normomagnesemic group, four out of nine (44%) were successfully resuscitated. A positive correlation was identified between normomagnesemia and successful resuscitation (P less than .01). There was no correlation between other electrolytes and successful resuscitation (P greater than .05).

Arrhythmias, Cardiac↗
PubMed1987

Prophylaxis of upper gastrointestinal tract bleeding in mechanically ventilated patients. A randomized study comparing the efficacy of sucralfate, cimetidine, and antacids.

Sixty-two mechanically ventilated patients were randomized into three study groups to compare the efficacy of sucralfate vs cimetidine and antacid regimens for the prevention of upper gastrointestinal tract bleeding. Only five study patients (8%) developed bright-red blood per nasogastric tube; four patients received the antacid regimen and one received cimetidine. None of the patients receiving sucralfate developed acute upper gastrointestinal tract bleeding. Bleeding was not severe enough in any patient to require endoscopy or surgery. There were no significant differences in the three groups when several major risk factors for gastrointestinal tract bleeding were analyzed, including sepsis, hypotension, steroid use, adult respiratory distress syndrome, gastric pH of 4 or less, previous peptic ulcer disease, peritonitis, and jaundice. A significantly higher incidence of acute renal failure was noted in the antacid-treated group when compared with the cimetidine and sucralfate groups. We find preliminary evidence that sucralfate is as efficacious as and more cost-effective than either cimetidine or antacids for prophylaxis of stress-related gastrointestinal tract bleeding in the critically ill ventilator-dependent patient.

Acute Kidney Injury↗
PubMed1986

Linkage analysis of Von Recklinghausen neurofibromatosis: chromosomes 4 and 19.

This report describes a study that examines the hypotheses of genetic linkage between the autosomal dominant disorder neurofibromatosis (NF) and loci on human chromosomes 4 and 19. Twelve Utah families were evaluated for evidence of possible linkage of NF to six known markers on chromosome 4 and five markers on chromosome 19. Due to previous reports suggesting tight linkage of NF to the GC locus on chromosome 4 and the C3 (linked to myotonic dystrophy) locus on chromosome 19, these two markers were of particular interest. For the Utah families the cumulative LOD score for GC was -4.81 (r = 0.05). Cumulative LOD scores were -0.90 (r = 0.05) and -1.01 (r = 0.05) for C3 serum determinations and a C3 DNA polymorphism respectively. Linkage data is also included on all individual informative families for the GC and C3 loci to specifically address the question of heterogeneity. Linkage data is consistent with, but does not strongly support, the existence of heterogeneity implicating both the GC locus on chromosome 4 and the C3 locus on chromosome 19. A compilation of cumulative LOD scores from this and other current linkage studies produces values that in the absence of heterogeneity refute previous reports for tight linkage of NF to GC and to C3.

Adolescent↗
PubMed1985

Dominant inheritance of adenomatous colonic polyps and colorectal cancer.

Except in the rare polyposis syndromes, the contribution of heritable factors to the genesis of colorectal cancer and adenomatous polyps is not well understood. We examined the inheritance of susceptibility to colonic polyps and cancer in a large Utah pedigree with multiple cases of common colorectal cancer but no recognizable inheritance pattern among them. Inheritance was clarified, however, by systematic screening for colonic polyps in pedigree members and spouse controls, using flexible proctosigmoidoscopy. One or more adenomatous polyps were found in 21 per cent of family members (41 of 191) but in only 9 per cent of controls (12 of 132) (P less than 0.005). Pedigree analysis was performed with likelihood methods that compared random occurrence of cancer and polyps with autosomal recessive and autosomal dominant patterns of inheritance. The analysis suggested that the observed excess of discrete adenomatous polyps and colorectal cancers was the result of an inherited autosomal dominant gene for susceptibility, rather than an inherited recessive gene for susceptibility or a chance occurrence. This type of inheritance of colorectal polyps and cancer may be more common than previously recognized.

Adult↗
PubMed1984

Genetic Analysis Workshop II: segregation and three-locus linkage analysis.

Data stimulated for Genetic Analysis Workshop II were analyzed using PAP. Segregation analysis showed a simple recessive mode of inheritance for data set 2 while no conclusions could be made about the mode of inheritance for data set 3. Pairwise linkage analysis suggested three linkage groups, but three-locus analysis did not provide strong evidence for the gene order within these groups. For three of the four three-locus comparisons performed, three-locus analysis suggested the simulated order. In only one case did the pairwise analysis suggest the simulated order, indicating the necessity for multi-locus analysis for gene order.

Chromosome Mapping↗
PubMed1984

Possible linkage of a breast cancer-susceptibility locus to the ABO locus: sensitivity of LOD scores to a single new recombinant observation.

We present evidence of a pedigree in which a major gene for breast cancer-susceptibility appears to segregate in a dominant fashion. Linkage analysis suggests that the breast cancer-susceptibility locus in this family may be linked to the ABO locus, which is located on band q34 of chromosome 9. At an early stage in the analysis, a LOD score of 3.0 for zero recombination was obtained for linkage between ABO and the susceptibility locus, but a single recombinant reduced the LOD score to 1.72 at a recombination fraction of 0.06. A final observation of a nonrecombinant brings the LOD score for this pedigree to 1.99 at theta = 0.05. We attempt to put these results in perspective by discussing the sensitivity of the LOD score to the next observation. Examples of the volatility of LOD scores are given. These simple calculations show that tight linkage represents the worst case for the interpretation of a LOD score of 3.0. Finally, we discuss the linkage between the breast cancer-susceptibility locus and the ABO blood group and approaches to confirming or denying this result.

ABO Blood-Group System↗
PubMed1983

Sister chromatid exchange: variation by age, sex, smoking, and breast cancer status.

Variation in sister chromatid exchange (SCE) frequency in lymphocytes of 125 persons was compared using a multivariate general linear model. The study was performed to determine whether SCE frequency differs with respect to age, sex, smoking, and breast cancer status. Study subjects were divided into: members of two branches of families having an excess of cancer (primarily breast) including a brother and sister in one family who developed nonbreast malignancies within 1 yr of the study; women in both families successfully treated for breast cancer (all at least 5 yr posttreatment); and women from the general population with confirmed breast cancer. Controls consisted of spouses who married into the high-risk kindreds, hospital personnel, and others (primarily tradesmen without history of occupational exposure). Results show that: (1) Women with active breast cancer have a significantly higher mean SCE frequency than control women or women greater than 5 yr posttreatment for breast cancer; (2) Cigarette smokers show a significantly higher number of SCEs than was observed in nonsmokers; (3) The increase in SCE level in smokers is dose-related to exposure as measured by cumulative pack-years; (4) SCE values in both high-risk families are not significantly different from controls; (5) Neither the age nor sex of the individual affects SCE frequency; and (6) The observed distribution of exchanges agrees with that expected based on the proportion of the genome represented by each chromosome group.

Adult↗