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Biomedical subjects

J Peck

Publications and source records attributed to J Peck.

18 recordsLinked to original sources
PubMed2001

Comparison of carotid endarterectomy at high- and low-volume hospitals.

BACKGROUND: Population-based studies have demonstrated better outcomes for carotid endarterectomies at high-volume hospitals. METHODS: This is a 2-year retrospective review of carotid procedures at two low-volume hospitals (n = 156) and one high-volume hospital (n = 404) in the metropolitan area of Portland, Oregon. RESULTS: There were no significant differences in 30-day mortality and stroke rates for carotid endarterectomies when comparing low- and high-volume hospitals (P = 0.59). These were comparable rates despite the fact that the low-volume hospitals had significantly older patients (P <0.001), more smokers (P <0.001), more patients with an indication of a previous nondisabling stroke (P <0.01), and fewer patients who were asymptomatic (P <0.01). CONCLUSION: The regionalization of carotid endarterectomy into high-volume hospitals is not justified by the findings of this study. Carotid endarterectomy performed by well-trained, experienced surgeons in low-volume hospitals is a safe procedure.

Age Factors↗
PubMed2000

Mean arterial pressure, pregnancy induced hypertension, and preeclampsia. Evaluation as independent risk factors and as surrogates for high maternal serum alpha-protein in estimating breast cancer risk.

PURPOSE: Data from a nested case-control study were analyzed to examine high mean arterial pressure (MAP), hypertension of pregnancy and preeclampsia as independent predictors, and as surrogate markers for elevated Alpha-fetoprotein (AFP) levels in evaluating breast cancer risk.METHODS: Cases (n = 205) were identified by the California Cancer Registry from a cohort of pregnant women who were part of the Kaiser Health Plan and took part in the Child Health and Development Studies initiated by the University of California, Berkeley, from June 1959 to September 1966. Controls (n = 337) were selected by randomized recruitment from the same cohort probability matched to cases by distribution of birth dates of cases.RESULTS: High MAP was associated with breast cancer risk, and was different across quartiles of age at first full term pregnancy. Odds Ratios across quartiles were 0.24 (95% CI = 0.08-0.71), 0.84 (95% CI = 0.39-1.66), 1.00 (referent), and 2.50 (95% CI = 1.21-5.13). Neither diagnosed preeclampsia nor hypertension of pregnancy showed any association with breast cancer risk. When both high Alpha-fetoprotein and high mean arterial pressure were entered into the same analysis neither changed the odds ratio for the other more than eight percent. Additionally, AFP level was not a linear function of MAP.CONCLUSIONS: Although the pattern of odds ratios across quartiles of age at first full term pregnancy were similar for the two variables it can not be concluded that high MAP is an adequate surrogate for high levels of maternal serum AFP, but rather represents some related process which is in and of itself a risk factor for breast cancer.

Journal Article↗
PubMed2000

Prior hrt use, ethnicity and mammographic density.

PURPOSE: Mammographic density has been strongly associated with breast cancer risk in several studies. To clarify possible pathogenic mechanisms underlying this relationship, we assessed factors affecting mammographic density in postmenopausal women.METHODS: Percent density (PD) was measured on pre-randomization mammograms from 425 participants in the Women's Health Initiative clinical trial; no women were currently using HRT. Trained observers used a previously validated computer-assisted thresholding technique to measure PD (ratio of dense areas to breast area) on craniocaudal films. Univariate relationships were assessed between PD and age, parity, education, history of HRT use, age at first birth, abortion history, alcohol use, serum cholesterol, physical activity, smoking, dietary fat intake, body-mass index (BMI), and waist-to-hip ratio (WHR). Multivariable regression was used to identify predictors of PD (log transformed), controlling for confounders.RESULTS: PD ranged from 0-60% with mean 8%. Age, gravidity, BMI, and WHR were negatively associated with PD. Mean PD in the highest tertiles of BMI and WHR was nearly half that in the lowest. Ethnicity (50% white, 28% black, and 19% Hispanic) and hysterectomy status (50% had intact uterus) were unassociated with PD. Controlling for age, BMI, WHR, smoking, hysterectomy status, prior HRT, and nulliparity, mean PD differed significantly by ethnicity, with black women having highest PD. However, the effect of prior HRT use differed by uterine status. In women with uteri intact, ethnicity, but not prior HRT use, was related to PD after controlling for age, BMI, and WHR. In hysterectomized women, ethnicity was unrelated to PD, while previous HRT was associated with lower PD.CONCLUSIONS: Gravidity, ethnicity and body shape and size are associated with mammographic density in postmenopausal women. Previous hormone use predicts lower PD, but only among hysterectomized women. This may be due to the higher frequency of oophorectomies in this group, which may lower PD and increase likelihood of HRT use. Planned analyses of entire sample of 1050 women will clarify the effect of these and other factors on density, and on density change in followup mammograms.

Journal Article↗
PubMed2000

The clinical role of noncontrast helical computed tomography in the diagnosis of acute appendicitis.

BACKGROUND: The accuracy of noncontrast helical computed tomography (CT) for appendicitis has recently been demonstrated. What is its clinical utility? METHODS: This was a retrospective review of 443 consecutive community hospital patients evaluated for acute appendicitis over an 18-month period using limited pelvic CT scan or clinical acumen alone. RESULTS: Appendicitis was pathologically proven in 158 patients. The negative appendectomy rate was 5.4%. The best radiological indicators for a positive CT for appendicitis were pericecal inflammation (88%) and appendicolith(57%). Appendiceal CT was found to have a 92% sensitivity, 99.6% specificity, and a 97.5% accuracy. There were 260 patients who had a negative CT; 243 of these were sent home. Alternative diagnoses were identified in 22% of patients. CONCLUSIONS: The liberal use of noncontrast helical CT results in a low negative appendectomy rate and a high degree of confidence that a negative CT will allow patients to be sent home safely.

Acute Disease↗
PubMed1997

Bradycardia induced from stimulation of the left versus right central nucleus of the amygdala.

Studies have demonstrated that the predominant effect of stimulation of the central nucleus of the amygdala is one of heart rate deceleration. Anatomical studies have shown that projections from the central nucleus to the cardioinhibitory neurons in the medulla are ipsilateral and that projections of the left or right vagal efferents to the heart innervate different nodal points. The results of this study suggest that stimulation of the central nucleus of the amygdala from either the left or right hemisphere produced similar increases in heart period. These results are discussed in terms of the effects of the localization of epileptic foci in the temporal lobes on the cardiovascular system.

Amygdala↗
PubMed1997

Bifurcation, bursting, and spike frequency adaptation.

Many neural systems display adaptive properties that occur on time scales that are slower than the time scales associated with repetitive firing of action potentials or bursting oscillations. Spike frequency adaptation is the name given to processes that reduce the frequency of rhythmic tonic firing of action potentials, sometimes leading to the termination of spiking and the cell becoming quiescent. This article examines these processes mathematically, within the context of singularly perturbed dynamical systems. We place emphasis on the lengths of successive interspike intervals during adaptation. Two different bifurcation mechanisms in singularly perturbed systems that correspond to the termination of firing are distinguished by the rate at which interspike intervals slow near the termination of firing. We compare theoretical predictions to measurement of spike frequency adaptation in a model of the LP cell of the lobster stomatogastric ganglion.

Action Potentials↗
PubMed1996

Concurrent Lyme disease and babesiosis. Evidence for increased severity and duration of illness.

OBJECTIVE: To determine whether patients coinfected with Lyme disease and babesiosis in sites where both diseases are zoonotic experience a greater number of symptoms for a longer period of time than those with either infection alone. DESIGN: Community-based, yearly serosurvey and clinic-based cohort study. SETTING: Island community in Rhode Island and 2 Connecticut medical clinics from 1990 to 1994. STUDY PARTICIPANTS: Long-term residents of the island community and patients seeking treatment at the clinics. MAIN OUTCOME MEASURES: Seroreactivity to the agents of Lyme disease and babesiosis and number and duration of symptoms. RESULTS: Of 1156 serosurvey subjects, 97 (8.4%) were seroreactive against Lyme disease spirochete antigen, of whom 14 (14%) also were seroreactive against babesial antigen. Of 240 patients diagnosed with Lyme disease, 26 (11%) were coinfected with babesiosis. Coinfected patients experienced fatigue (P = .002), headache (P < .001), sweats (P < .001), chills (P = .03), anorexia (P = .04), emotional lability (P = .02), nausea (P = .004), conjunctivitis (P = .04), and splenomegaly (P = .01) more frequently than those with Lyme disease alone. Thirteen (50%) of 26 coinfected patients were symptomatic for 3 months or longer compared with 7 (4%) of the 184 patients with Lyme disease alone from whom follow-up data were available (P < .001). Patients coinfected with Lyme disease experienced more symptoms and a more persistent episode of illness than did those (n = 10) experiencing babesial infection alone. Circulating spirochetal DNA was detected more than 3 times as often in coinfected patients as in those with Lyme disease alone (P = .06). CONCLUSIONS: Approximately 10% of patients with Lyme disease in southern New England are coinfected with babesiosis in sites where both diseases are zoonotic. The number of symptoms and duration of illness in patients with concurrent Lyme disease and babesiosis are greater than in patients with either infection alone. In areas where both Lyme disease and babesiosis have been reported, the possibility of concomitant babesial infection should be considered when moderate to severe Lyme disease has been diagnosed.

Adolescent↗
PubMed1995

The effect of amygdaloid kindling on heart period and heart period variability.

Two studies were conducted on rats to assess the effects of amygdaloid kindling on baseline measures of heart period and heart period variance. The results indicate that seizure activity was associated with increased vagal influence on heart period marked by sinus bradycardia and decreased beat-to-beat variability. The resultant bradycardia was enhanced following each seizure and persisted for at least a one-week period of time. The results are discussed in terms of the role of vagal tone in influencing abnormal cardiac patterns which could result in sudden unexplained death in some epileptic patients.

Amygdala↗
PubMed1992

Health care and AIDS.

The acquired immune deficiency syndrome (AIDS) is a harbinger for change in health care. There are many powerful forces poised to transform the industrialized health care structure of the twentieth century, and AIDS may act as either a catalyst or an amplifier for these forces. AIDS could, for example, swamp local resources and thereby help trigger national reform in a health care system that has already lost public confidence. AIDS can also hasten the paradigm shift that is occurring throughout health care. Many of the choices society will confront when dealing with AIDS carry implications beyond health care. Information about who has the disease, for example, already pits traditional individual rights against group interests. Future information systems could make discrimination based upon medical records a nightmare for a growing number of individuals. Yet these systems also offer the hope of accelerated progress against not only AIDS but other major health threats as well. The policy choices that will define society's response to AIDS can best be made in the context of a clearly articulated vision of a society that reflects our deepest values.

Acquired Immunodeficiency Syndrome↗
PubMed1981

Correlation between uropathogenic properties of Escherichia coli from urinary tract infections and the antibody-coated bacteria test and comparison with faecal strains.

Strains of Escherichia coli isolated from adult females with symptomatic urinary tract infection were found to possess the following properties significantly more frequently than faecal strains: (i) high K-antigen titre: (ii) haemolysin; (iii) type 1 pili; (iv) mannose-resistant haemagglutination; (v) fermentation of dulcitol and salicin; (vi) O serotype 2, 6 and 75; (vii) H serotype 1. E. coli isolated form urine specimens containing significant numbers of antibody-coated bacteria were richer in these seven properties than strains from urines without detectable antibody coated bacteria. The O and H serotypes of E. coli obtained from patients with urinary tract infection in two New Zealand cities were compared with those reported in the world literature and found to be similar.

Adolescent↗
PubMedDate not supplied

Developing a synagis clinic for respiratory syncytial virus prophylaxis.

Respiratory Syncytial Virus (RSV) can be devastating to premature infants and children with chronic lung disease. Palivizumab (Synagis) is a monoclonal antibody that is administered monthly by injection to prevent RSV infection in infants at high risk. This article describes a nurse-run ambulatory clinic to provide RSV prophylaxis. Coordination with other agencies, including community neonatal intensive care units, was essential to the clinic's success. For each of its first 2 years of operation, 24 infants and their families attended the clinic once each month for 5 months throughout the RSV season. Outcomes for this patient population were compared to outcomes reported in the literature, and include reduced RSV-related hospitalizations and reduced days of hospitalization.

Ambulatory Care Facilities↗