PubMed Health⌕ Search

Biomedical subjects

R J Peterson

Publications and source records attributed to R J Peterson.

At least 19 recordsLinked to original sources
PubMed2005

Off pump coronary artery bypass surgery for significant left ventricular dysfunction: safety, feasibility, and trends in methodology over time--an early experience.

OBJECTIVE: To examine the safety and applicability of off pump coronary artery bypass surgery (OPCAB) in patients with significant left ventricular dysfunction and to discuss the clinical implications for the surgical methods. DESIGN: Retrospective study. SETTING: Tertiary care university affiliated referral centre. PARTICIPANTS: 353 consecutive patients with preoperative left ventricular ejection fraction < or = 35% who underwent coronary artery bypass over a three year period. MAIN OUTCOME MEASURES: Postoperative morbidity and mortality. METHODS: 144 patients operated by OPCAB were compared with 209 patients operated by conventional coronary artery bypass. Multivariate and univariate analyses were performed on the pre- and postoperative variables to predict risk factors associated with hospital morbidity and mortality. RESULTS: Patients in the OPCAB group were more likely to be women and to have congestive heart failure, chronic obstructive pulmonary disease, hypertension, and diabetes; patients in the on pump group were more likely to have had a recent myocardial infarction and to have more severe angina pectoris and an urgent/emergent status. The groups did not differ significantly in length of stay, major postoperative complication rates, or mortality. Comparison of the impact of the procedures on surgical methods over time showed an increase in the use of OPCAB (13% to 67%), without any impact on morbidity or mortality. CONCLUSIONS: OPCAB is feasible and applicable for patients with depressed left ventricular function. This high risk group can potentially benefit from the off pump approach.

Aged↗
PubMed2001

Statistical estimation and pedigree analysis of CCR2-CCR5 haplotypes.

As more SNP marker data becomes available, researchers have used haplotypes of markers, rather than individual polymorphisms, for association analysis of candidate genes. In order to perform haplotype analysis in a population-based case-control study, haplotypes must be determined by estimation in the absence of family information or laboratory methods for establishing phase. Here, we test the accuracy of the Expectation-Maximization (EM) algorithm for estimating haplotype state and frequency in the CCR2-CCR5 gene region by comparison with haplotype state and frequency determined by pedigree analysis. To do this, we have characterized haplotypes comprising alleles at seven biallelic loci in the CCR2-CCR5 chemokine receptor gene region, a span of 20 kb on chromosome 3p21. Three-generation CEPH families (n=40), totaling 489 individuals, were genotyped by the 5'nuclease assay (TaqMan). Haplotype states and frequencies were compared in 103 grandparents who were assumed to have mated at random. Both pedigree analysis and the EM algorithm yielded the same small number of haplotypes for which linkage disequilibrium was nearly maximal. The haplotype frequencies generated by the two methods were nearly identical. These results suggest that the EM algorithm estimation of haplotype states, frequency, and linkage disequilibrium analysis will be an effective strategy in the CCR2-CCR5 gene region. For genetic epidemiology studies, CCR2-CCR5 allele and haplotype frequencies were determined in African-American (n=30), Hispanic (n=24) and European-American (n=34) populations.

Alleles↗
PubMed2000

Measurement of pi(0)pi(0) production in the nuclear medium by pi(-) interactions at 0.408 GeV/c.

We report on an investigation of the (pi(-),pi(0)pi(0)) reaction by means of measurements of the pi(0)pi(0) invariant mass distributions from pi(-) interactions on H, D, C, Al, and Cu targets at p(pi(-)) = 0.408 GeV/c. The sharp, strong peak in the pi(+)pi(-) invariant mass near 2m(pi) reported by the CHAOS Collaboration is not seen in our pi(0)pi(0) data. However, we do observe a change in the shape of the pi(0)pi(0) invariant mass spectrum for the different targets, indicating that the pi(0)pi(0) interaction diminishes in the nuclear medium as represented by nuclei D, C, Al, and Cu, compared to hydrogen.

Journal Article↗
PubMed2000

Use of denaturing HPLC to map human and murine genes and to validate single-nucleotide polymorphisms.

Linkage mapping has been extensively applied in the murine and human genomes. It remains a powerful approach to mapping genes and identifying genetic variants. As genome efforts identify large numbers of single-nucleotide polymorphisms, it will be critical to validate these polymorphisms and confirm their gene assignment and chromosomal location. The presence of pseudogenes can confuse such efforts. We have used denaturing HPLC to identify polymorphisms in human genes and to genotype individuals in selected CEPH pedigrees. The same approach has been applied to the mapping of murine genes in interspecies backcross animals. This strategy is rapid, accurate and superior in several respects to other technologies.

5'-Nucleotidase↗
PubMed2000

5' Nuclease assays for the loci CCR5-+/Delta32, CCR2-V64I, and SDF1-G801A related to pathogenesis of AIDS.

BACKGROUND: Variations within the human genome play important roles in human disease. To study variations related to susceptibility to AIDS, we have developed 5' nuclease assays that eliminate post-PCR molecular biology steps. METHODS: TaqMan assays based on the 5' nuclease activity of Taq polymerase and fluorescent resonance energy transfer were developed to score alleles at the biallelic loci CCR5-+/Delta32, CCR2-V64I and SDF1-G801A. For each assay, 72 samples were analyzed. Data collection and analysis were performed on the Prism 7700 Sequence Detection System. For comparison with gel electrophoresis methods, each locus was also scored on a subset of 24 samples, using restriction enzymes or single-strand conformational polymorphism (SSCP). RESULTS: Clear allelic discrimination was obtained on each of the 72 samples for all three TaqMan assays. The TaqMan scores for the subset of 24 samples were concordant with the restriction enzyme and SSCP scores. CONCLUSIONS: Because of its simplicity, speed, and potential for automation and miniaturization, TaqMan is an excellent candidate for investigation of genetic variation in clinical, research, and forensic settings.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Nucleotide sequence diversity in non-coding regions of ALDH2 as revealed by restriction enzyme and SSCP analysis.

The simultaneous analysis of closely linked nucleotide substitutions has recently become possible. However, it is not known whether the construction of molecular haplotypes will be a generally useful strategy for nuclear genes. Furthermore, whereas mobility-shift methods are widely used for the discovery of nucleotide substitutions, the yield of these methods has rarely been evaluated. This paper investigates these issues in non-coding regions of ALDH2, the gene that encodes aldehyde dehydrogenase 2 (ALDH2). Screening 20 Europeans, 20 native Americans, and 20 Asians by using restriction enzyme and single-strand conformation polymorphism (SSCP) analysis has revealed 16 variable sites. SSCP yields slightly fewer than the number of nucleotide substitutions predicted by the restriction enzyme digests. Estimates of nucleotide diversity are similar to those of other genes, suggesting that the pattern of polymorphism in ALDH2 offers a preview of what can be expected in many human nuclear genes. Eight of the variable sites discovered here and four sites discovered by others have been genotyped in 756 people from 17 populations across five continents. An expectation-maximization method has used to estimate haplotype states and frequencies. Only three haplotypes are common worldwide, and a fourth haplotype is common in, but private to, Asia. Although allele frequencies differ among sites, linkage disequilibrium is almost maximal across ALDH2. This suggests that haplotype construction at ALDH2 is particularly successful. The ALDH2 result, in conjunction with linkage disequilibrium results from other genes, indicates that haplotype construction will be a generally useful genomic strategy.

Aldehyde Dehydrogenase↗
PubMed1999

Ultra-fast track hospital discharge using conventional cardiac surgical techniques.

BACKGROUND: Recent introduction of minimally invasive adult cardiac surgical techniques has emphasized the advantage of early hospital discharge. However, we chose an alternative approach to determine the safety, efficacy, and feasibility of ultra-fast track protocols while retaining both standard surgical exposure (median sternotomy) and conventional cardiac surgical techniques (hypothermia, cardiopulmonary bypass with cardiac arrest, and optimal myocardial protection). METHODS: From September 1995 to January 1998, a total of 258 consecutive patients underwent cardiac procedures by a single surgeon. Acceleration of clinical pathways was used to initiate earlier discharges. Stringent postdischarge follow-up was implemented. Prospectively entered data were then analyzed retrospectively. RESULTS: A variety of isolated as well as combined coronary and valve procedures were performed. Of the 258 patients operated on during this entire study period, a total of 144 patients (56%) were discharged within postoperative days 1 to 4 (ultra-fast track discharge). Over the past 12 months, this incidence increased to 70% (76 of 108 patients). Approximately 50% of these patients were operated on urgently or emergently. To date, there have been no deaths in this ultra-fast track group. There were eight brief readmissions, of which one was for rewiring of a noninfected sternal dehiscence, and the remaining were for cardiac diagnostic studies or a noncardiac problem altogether. CONCLUSIONS: Conventional cardiac operation can allow ultrafast hospital discharges while retaining the advantage of time-tested techniques and providing wider application without requiring new or additional training or equipment.

Adult↗
PubMed1999

Effects of worldwide population subdivision on ALDH2 linkage disequilibrium.

The effect of human population subdivision on linkage disequilibrium has previously been studied for unlinked genes. However, no study has focused on closely linked polymorphisms or formally partitioned linkage disequilibrium within and among worldwide populations. With an emphasis on population subdivision, the goal of this paper is to investigate the causes of linkage disequilibrium in ALDH2, the gene that encodes aldehyde dehydrogenase 2. Haplotypes for 756 people from 17 populations across five continents were estimated by maximum-likelihood from genotypes at six closely linked ALDH2 nucleotide substitutions. Linkage disequilibrium was partitioned into three components: within populations, among populations within continents, and among continents. It was found that population subdivision among continents had a larger and more disparate effect on linkage disequilibrium than subdivision among local populations. Further, linkage disequilibrium did not increase with population divergence as predicted by a simple model. Rather, the patterns of linkage disequilibrium were complicated because of the interplay of a near absence of recombination, the linkage disequilibrium that existed prior to the divergence of modern humans, subsequent mutation, population subdivision, random genetic drift, and perhaps natural selection. These results suggest that simple models may not well predict patterns of linkage disequilibrium in human populations.

Aldehyde Dehydrogenase↗
PubMed1996

The evaluation of pediatric trauma care using audit filters.

OBJECTIVE: To evaluate the experience of a pediatric trauma system with specific reference to prehospital, trauma center resuscitation, and critical care phases of treatment. DESIGN: Descriptive review of concurrent audit. SETTING: A tertiary care referral adult and pediatric trauma center. PATIENTS: All pediatric trauma victims in the trauma registry (includes patients < or = 14 years old, who died or were hospitalized for > or = 24 hours). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Age, pediatric trauma, injury severity, and Glasgow Coma Scale scores as well as outcome (death or discharge disability score) were analyzed. Primary filters (those with the potential to contribute to morbidity and mortality), secondary filters (minor deviations from care), missed injuries and all deaths were reviewed. Of 250 patients in the registry, 20 died. One hundred thirteen had filters, with 49 having primary filters (34 with one, 14 with two, and one with four filters). Fifty percent of primary filters occurred in the prehospital phase of care with inadequate airway management and venous access accounting for 60%. Overall, primary filters occurred more commonly in patients with severe injuries (lower Pediatric Trauma and Glasgow Coma Scale and higher Injury Severity scores). Primary filters were also statistically more common in patients who died or who were disabled. In three patients (25%) who died, our review suggested that filters may have contributed to demise. Missed injuries were mostly extremity fractures and did not contribute to mortality or long-term morbidity. CONCLUSION: Deviations from care occur, even in a dedicated pediatric trauma system. Mortality of and by itself is not an adequate indicator of the quality of function of a trauma system. Since most primary filters occurred outside of the trauma center, improvement in trauma outcome may be expected with better training of personnel involved in the prehospital care of injured children. A comprehensive review of death and disability should include audit filters of prehospital care, triage, definitive care, and rehabilitation.

Child↗
PubMed1995

Comparison of transtracheal and extravascular Doppler determinations of stroke volume and cardiac output at various states of volume loading in piglets.

OBJECTIVE: To assess the applicability of a new technology in neonates. Transtracheal Doppler and extravascular Doppler determinations of stroke volume and cardiac output were compared with thermodilution measurements at various states of volume loading in an animal model. DESIGN: Prospective, descriptive study. SETTING: Animal research laboratory at a university medical center. SUBJECTS: Fourteen newly weaned piglets, weighing 2.8 to 6.5 kg. INTERVENTIONS: Doppler probes were placed on the endotracheal tube tip (transtracheal Doppler) and directly on the aortic adventitia (extravascular Doppler). A 4-Fr thermodilution catheter was inserted in the pulmonary artery. Stroke volume and cardiac output determinations were recorded at baseline, after a 15-mL/kg volume load and after successive 15-mL/kg blood withdrawals to exsanguination or a systolic blood pressure of < 20 mm Hg. MEASUREMENTS AND MAIN RESULTS: Transtracheal and extravascular Doppler measurements of cardiac output were not significantly different from thermodilution at any physiologic state. These techniques were able to measure stroke volumes and cardiac outputs at the low levels seen in severe hemorrhagic shock. CONCLUSIONS: Transtracheal Doppler and extravascular Doppler measurements of cardiac output compare favorably with thermodilution. These methods effectively followed trends from alterations in intravascular volume, even at very high heart rates and small stroke volumes. Transtracheal Doppler and extravascular Doppler should yield useful information in critically ill neonatal patients, where data regarding stroke volume and cardiac output may be useful in clinical management.

Animals↗
PubMed1994

Pediatric and adult thoracic trauma: age-related impact on presentation and outcome.

UNLABELLED: To assess the impact of age on presentation and outcome, 2,415 cases involving blunt and penetrating thoracic trauma over an 8-year period were reviewed retrospectively from a single level I trauma center. Of the 2,073 patients alive on arrival, 79 were 12 years of age or less (children), 137 were 13 to 17 years of age (adolescent), 1,742 were 18 to 59 years of age (adults), and 115 were 60 years of age or more (elderly). Chi-square analysis was performed relative to presentation (blunt versus penetrating), need for thoracotomy, and hospital mortality. Although blunt thoracic trauma comprised 64/79 of children (81%) and 90/115 of the elderly (78%), penetrating thoracic trauma was more common for adolescents 79/137 (58%) and adults 1013/1742 (58%) (p < 0.05). There was no significant difference in need for thoracotomy among the four age groups after blunt thoracic trauma. For penetrating trauma, however, there was a significantly higher incidence of thoracotomy in children as compared with the other three age groups (p < 0.05). IN CONCLUSION: (1) Blunt injuries comprised a greater proportion of thoracic trauma in children and the elderly. (2) In this series, children with penetrating thoracic trauma underwent thoracotomy more frequently. (3) Hospital mortality appeared to be increased for the elderly. (4) Analyses of pediatric thoracic trauma must separate children from adolescent age groups.

Adolescent↗
PubMed1994

Transtracheal Doppler in infants and small children following surgery for congenital heart disease: rational use of an improved technology.

OBJECTIVE: To compare measurements of cardiac output utilizing an improved transtracheal Doppler technology with measurements obtained using two-dimensional echocardiography. DESIGN: Prospective, descriptive study. SETTING: Cardiovascular intensive care unit at a university medical center. PATIENTS: Fourteen children ranging in age from 14 days to 3 yrs (mean 1.3 +/- .97 yrs) following surgery for complex congenital heart disease. INTERVENTIONS: Simultaneous cardiac output determinations using transtracheal Doppler and two-dimensional echocardiography were compared. Cardiac output was determined using measurement of blood velocity and diameter of the ascending aorta following surgery. Direct aortic diameter measurements made at operation were compared with measurements obtained by transtracheal Doppler, two-dimensional echocardiography and angiography. RESULTS: The mean difference in aortic root diameter between measurements made directly at operation and transtracheal Doppler was 5%, compared with 13% by two-dimensional echocardiography, and 21% by angiography, a significant difference by analysis of variance (F[3,31],p < .007). Post hoc comparisons demonstrated significant (p < .05) differences between echocardiography and angiographic aortic diameters. The mean difference between transtracheal Doppler and echocardiographic determination of cardiac output was 10.9% (t[10] = -1.37, p = .007). CONCLUSIONS: An improved transtracheal Doppler technology compares favorably with echocardiographic determination of cardiac output in infants and young children. This improved technology may provide a useful means to assess cardiac output and may allow titration of therapy in critically ill infants and children.

Aftercare↗
PubMed1994

Pediatric penetrating thoracic trauma: a five-year experience.

Penetrating thoracic trauma is managed nonoperatively in 85% of adult patients. We hypothesized that similar trauma in children would lead to proportionately more vital tissue damage and a higher rate of operative intervention. The pediatric penetrating thoracic trauma experience of a level one trauma center was analyzed over a five-year period. Data reviewed included circumstances of injury, Pediatric Trauma Score (PTS), interventions performed, and outcome. Of 61 children with thoracic trauma, 13 had penetrating injuries. Of these 13, seven were unintentional (five from firearms); the rest were caused by assaults. Seven patients (54%) underwent thoracotomy or laparotomy. All five patients with a PTS < 8 underwent surgical intervention, whereas only two of the eight patients with a PTS > or = 8 needed surgery (P < 0.05). There was one death. We reached the following conclusions: 1) Children with penetrating thoracic trauma are more likely to require surgical intervention than adults. 2) Penetrating thoracic trauma in children should elicit a thorough search for operative lesions. 3) About half these injuries are unintentional, and thus potentially preventable.

Adolescent↗
PubMed1994

A multistate model of fecundability and sterility.

This paper develops a multistate hazards model for estimating fecundability and sterility from data on waiting times to conception. Important features of the model include separate sterile and nonsterile states, a distinction between preexisting sterility and sterility that begins after initiation of exposure, and log-normally distributed fecundability among nonsterile couples. Application of the model to data on first birth intervals from Taiwan, Sri Lanka, and the Amish shows that heterogeneity in fecundability is statistically significant at most ages, but that preexisting sterility and new sterility are unimportant before age 40. These results suggest that sterility may not be an important determinant of natural fertility until later reproductive ages.

Adolescent↗