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Biomedical subjects

C O'Connor

Publications and source records attributed to C O'Connor.

At least 19 recordsLinked to original sources
PubMed1992

N-methyl-D-aspartate receptor antagonist MK-801 and spatial memory representation: working memory is impaired in an unfamiliar environment but not in a familiar environment.

Female Sprague-Dawley rats were injected with the noncompetitive N-methyl-D-aspartate (NMDA) antagonist MK-801 or saline 30 min before daily testing in spatial working memory (WM) and reference memory (RM) procedures in an 8-arm radial maze. MK-801 impaired RM and WM acquisition but not performance when rats were trained to criterion before drug administration. Neither a 2-hr nor a 4-hr delay between the first and last 2 correct WM choices impaired long-term WM. MK-801 impaired WM performance in trained rats only when rats were tested in a new environment. Thus, 2 mechanisms may be required for relational memory: an NMDA-dependent mechanism for acquiring long-term spatial representations and an NMDA-insensitive mechanism for operating on these stored representations.

Animals↗
PubMed1991

Failure of adjuvant heparin to reduce myocardial ischemia in the early treatment of patients with unstable angina.

Although the efficacy of long-term administration of antithrombotic agents in unstable angina has been established, short-term effects on myocardial ischemia are unknown. A retrospective analysis was performed in 47 patients undergoing three-channel continuous ST segment monitoring as part of a multicenter trial using esmolol in unstable angina, in which 20 patients received a continuous heparin infusion during the initial assessment of chest pain. Concomitant medications included calcium channel blockers, beta-adrenergic blockers, nitrates, and aspirin in the majority of patients. Clinical variables between the heparin and no heparin groups were similar, except for fewer males and fewer total artery occlusions in the heparin group. No significant differences in the incidence or duration of ischemia were found in a 36 +/- 16 hour monitoring period. Forty percent of the heparin group had 35 episodes of ischemia with a mean of 11 +/- 10 minutes per episode and a total ischemic time of 48 +/- 39 minutes per patient with ischemia. Forty-four percent of the no heparin group had 47 episodes of ischemia with a mean of 13 +/- 13 minutes per episode and a total ischemic time of 58 +/- 47 minutes per patient with ischemia. Multiple linear regression analysis to adjust for intergroup differences did not alter the results. Eighty-five percent of all episodes were asymptomatic. Clinical events, such as episodes of chest pain, emergency coronary arteriography, or coronary revascularization, were also similar between groups. Thus the short-term administration of heparin did not alter the incidence or duration of ischemia in patients with unstable angina.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1991

Exploration for physicians of the mature minor doctrine.

The "mature minor doctrine" is the common-law rule that allows an adolescent who is mature to give consent for medical care. Ethical decisions regarding consent and confidentiality should be distinguished from legal requirements. Recent court decisions have altered the law, especially in regard to consent for refusal of life-sustaining treatment. There are statutory exceptions to the rule of parental consent regarding emergency care, sexually transmitted diseases, drug treatment, mental health care, pregnancy, contraception, and emancipation. A detailed analysis of the mature minor exception is presented, utilizing court case vignettes. There is minimal legal risk in allowing adolescents older than 14 years of age to give consent for treatments entailing small degrees of risk, when they can make adultlike decisions and demonstrate signs of maturity.

Adolescent↗
PubMed1991

Effects of simulated extracorporeal circulation on human leukocyte elastase release, superoxide generation, and procoagulant activity.

Activated leukocytes are thought to contribute to respiratory dysfunction, alterations in microvascular permeability, disseminated intravascular coagulation, and thrombosis, all of which can complicate extracorporeal circulation. The purpose of this work was to determine the effects of extracorporeal circulation on leukocyte functions likely to mediate organ damage. White blood cell counts in the bubble circuits (n = 5) fell to 51% +/- 7% (mean +/- standard error of the mean; p less than 0.05) of initial levels within 2 hours of recirculation. In contrast, counts from both the spiral coil (n = 5) and hollow-fiber (n = 5) groups remained at 91% +/- 12% and 100%, respectively. Plasma levels of human neutrophil elastase rose from 0.28 +/- 0.06 micrograms/ml to 3.14 +/- 0.36 micrograms/ml (p less than 0.05) and 0.20 +/- 0.02 micrograms/ml to 1.61 +/- 0.35 micrograms/ml (p less than 0.05) in bubble and spiral coil circuits, respectively, but from only 0.20 +/- 0.03 micrograms/ml to 0.96 +/- 0.42 micrograms/ml in the hollow-fiber circuit despite 2 hours of recirculation. Consistently, in response to N-formyl-L-methionyl-L-leucyl-L-phenylalanine, a chemotactic peptide, cells from spiral coil and bubble circuits released and generated significantly less elastase and superoxide anion, respectively. In contrast, neutrophils from the hollow-fiber circuits demonstrated enhancement of N-formyl-L-methionyl-L-leucyl-L-phenylalanine-induced elastase release and superoxide generation. Finally, mixed leukocytes from all circuits expressed procoagulant activity reaching statistical significance in bubble circuits. In conclusion, extracorporeal circulation has pronounced effects on neutrophil elastase release, superoxide anion generation, and leukocyte procoagulant activity. Spiral coil and bubble oxygenators cause granule release and, subsequently, reduced sensitivity to soluble agonists. In contrast, hollow-fiber oxygenators "prime" cells, actually enhancing reactivity. Recirculation through all circuits induces leukocyte procoagulant activity that is likely to contribute to surface-induced thromboses and excessive bleeding.

Blood Coagulation↗
PubMed1990

Prevalence of maternal HIV infection based on unlinked anonymous testing of newborn babies.

This pilot study established that unlinked anonymous testing of dried blood spots routinely collected on Guthrie cards for neonatal screening is a feasible method for monitoring HIV prevalence in women at the time of delivery. The method was sensitive, specific, and less expensive than more conventional ELISAs. 114,515 dried blood spots taken from cards collected in three Thames regions were tested for antibody to HIV-1. 28 samples were confirmed to be antibody positive by western blot (seroprevalence 0.24 per 1000). Unlinked anonymous screening of newborn babies should be extended to monitor the spread of HIV infection in the heterosexual population and to target preventive strategies and provision of health care.

Agglutination Tests↗
PubMed1989

Prognostic value of bronchoalveolar lavage in sarcoidosis: the critical influence of disease presentation.

There has been considerable disagreement about the prognostic value of bronchoalveolar lavage lymphocyte measurements in patients with sarcoidosis. This study looks at the influence of the type of disease presentation and the time since onset of symptoms on lavage fluid lymphocyte profiles in 99 patients studied at the time of their initial diagnosis. Patients who had an acute inflammatory onset of disease with erythema nodosum (n = 32) or acute uveitis (n = 17) almost invariably had high T lymphocyte helper:suppressor (TH:TS) ratios (mean 10.1, 95% confidence interval 7.7-12.5) and had a higher proportion of T lymphocytes in cells obtained at lavage (40%, 35-46%) than patients with a pulmonary presentation (n = 38) (TH:TS 2.9, 0.2-5.7; T lymphocytes 21%, 15-27%) or those studied after resolution of erythema nodosum (n = 12). The patients with recent erythema nodosum had the highest TH:TS ratios of any group (10.4, 8.1-12.7). Thus lavage T lymphocyte percentage and TH:TS are highest in patients with sarcoidosis studied soon after an acute onset with an inflammatory condition such as erythema nodosum or uveitis. Patients with an acute onset of sarcoidosis have a better prognosis than those with a more insidious presentation. The major influence of type of disease presentation and, in the case of patients with erythema nodosum, of time since onset of symptoms may in part explain why different centres have reported such diverse results regarding the value of bronchoalveolar lavage in predicting outcome in sarcoidosis. Studies where the case mix of patients includes a high proportion of patients with acute onset will not find a high TH:TS ratio or increased numbers or proportions of lavage lymphocytes to be indicators of a poor prognosis.

Acute Disease↗
PubMed1989

Type 3 procollagen peptide in bronchoalveolar lavage fluid. Poor indicator of course and prognosis in sarcoidosis.

To investigate the role of bronchoalveolar lavage type 3 procollagen peptide as a prognostic indicator in sarcoidosis, we measured type 3 procollagen N-terminal peptide levels in lavage fluids from 84 sarcoidosis patients and monitored disease progress in these patients for a period of 12 months. Lavage procollagen peptide levels were significantly elevated in sarcoidosis patients compared to control subjects (p less than 0.001). No association was observed between lavage type 3 procollagen peptide and disease severity, as assessed by lung function tests. Follow-up monitoring of patients failed to demonstrate any relationship between subsequent functional deterioration and initial lavage type 3 procollagen peptide. These results suggest that elevated lavage type 3 procollagen peptide concentrations in sarcoidosis may reflect increased type 3 collagen synthesis associated with the inflammatory process rather than signal an early event in the development of chronic disease.

Adult↗
PubMed1988

Adoption of thrombolytic therapy in the management of acute myocardial infarction.

A national survey of 1,065 physicians was carried out to document current use of thrombolytic therapy for acute myocardial infarction (AMI). In early 1987, thrombolytic therapy was used by 66% of respondents. Among those who used thrombolytic therapy, 92% used streptokinase, 13% used tissue-type plasminogen activator and 3% used urokinase. Most (72%) used intravenous administration exclusively and only 5% used intracoronary administration exclusively. Despite widespread acceptance of thrombolytic therapy, most physicians gave it to less than 25% of their patients. Duration of symptoms was rated as the single most important factor affecting the decision to use thrombolytic therapy; 45% had a time limit of less than 4 hours and 85% had a time limit of less than 6 hours. Complications of AMI and electrocardiographic findings were factors also considered in the decision to give this therapy. A physician's adoption of thrombolytic therapy was significantly associated with several characteristics: specialty type, number of AMI patients treated, physician age and access to cardiac catheterization. In addition, physicians using thrombolytic therapy had a significantly different use of medications and laboratory tests for all patients with AMI. This survey documents rapid acceptance of thrombolytic therapy for AMI, particularly in patients with short duration of symptoms or evidence of high risk.

Cardiac Catheterization↗
PubMed1988

Trends in physician management of uncomplicated acute myocardial infarction, 1970 to 1987.

To document current management of uncomplicated acute myocardial infarction (AMI), a national survey of 1,065 physicians was performed. Items from previous surveys in 1970 and 1979 were included to permit analysis of time trends in management. Median hospital stay dropped from 21 days in 1970 to 9 days in 1987. Use of beta blockers and aspirin doubled between 1979 and 1987, while use of anticoagulation and sulfinpyrazone dropped 4- to 10-fold. In 1987, coronary angiography was used commonly, especially in younger patients or those with either a non-Q-wave AMI, intravenous thrombolytic therapy or a positive exercise test. These findings document the increasingly aggressive approach to the management of patients with uncomplicated AMI.

Activities of Daily Living↗
PubMed1988

Late restenosis after emergent coronary angioplasty for acute myocardial infarction: comparison with elective coronary angioplasty.

The late restenosis rate after emergent percutaneous transluminal coronary angioplasty for acute myocardial infarction was assessed by performing outpatient follow-up cardiac catheterization in 79 (87%) of 91 consecutive patients who had been discharged from the hospital with a successful coronary angioplasty. The majority of patients (90%) received high dose intravenous thrombolytic therapy with streptokinase in addition to angioplasty. Similar follow-up data were obtained in 206 (90%) of 228 consecutive patients who had successful elective angioplasty during the same period. The interval from angioplasty to follow-up was 28 +/- 9 weeks for the myocardial infarction group and 30 +/- 11 weeks for the elective group. Baseline clinical variables were similar for both the myocardial infarction and elective groups except for a higher percentage of men in the infarction group (81 versus 63%, p = 0.001). The number of coronary lesions undergoing angioplasty and the incidence of intimal dissection were similar, but multivessel angioplasty was more common in the elective group (13 versus 4%, p = 0.02). The rate of in-hospital reocclusion was higher in the patients receiving angioplasty for myocardial infarction (13 versus 2%, p = 0.0001). At the time of late follow-up after hospital discharge, the patients with myocardial infarction were more often asymptomatic (79 versus 55%, p = 0.0001), and the rate of angiographic coronary restenosis was lower for the infarction group both overall (19 versus 35%, p = 0.006) and when multivessel angioplasty patients were excluded (19 versus 33%, p = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Collagenase and fibronectin in bronchoalveolar lavage fluid in patients with sarcoidosis.

Bronchoalveolar lavage fluid from 43 patients with biopsy proved sarcoidosis and 10 control subjects were assayed for fibronectin and collagenase activity. Fibronectin was significantly increased in the group with sarcoidosis and was found to be positively correlated with angiotensin converting enzyme activity, protein concentration, percentage of T cells and helper:suppressor ratios in the lavage fluid. Increased fibronectin in the bronchoalveolar lavage fluid was not related to functional or radiographic indices of interstitial disease and did not identify patients subsequently requiring treatment. Latent collagenase was present in bronchoalveolar lavage fluid from 16 patients with sarcoidosis but not in any control sample. There was no association between the collagenase activity and the cell profiles of the lavage fluid. Yet carbon monoxide transfer factor was decreased in patients with bronchoalveolar lavage fluid collagenase. Ten of 16 patients with bronchoalveolar lavage fluid collagenase had radiographic class III or IV disease and a disease duration of more than two years. On follow up 62% of patients with bronchoalveolar lavage fluid collagenase required subsequent treatment, compared with only 23% of patients without collagenase. These results indicate an association between bronchoalveolar lavage fluid collagenase and progressive, prolonged disease in sarcoidosis, whereas increased bronchoalveolar lavage fluid fibronectin is associated with indices of disease activity.

Adult↗
PubMed1987

Emotion knowledge: further exploration of a prototype approach.

Recent work on natural categories suggests a framework for conceptualizing people's knowledge about emotions. Categories of natural objects or events, including emotions, are formed as a result of repeated experiences and become organized around prototypes (Rosch, 1978); the interrelated set of emotion categories becomes organized within an abstract-to-concrete hierarchy. At the basic level of the emotion hierarchy one finds the handful of concepts (love, joy, anger, sadness, fear, and perhaps, surprise) most useful for making everyday distinctions among emotions, and these overlap substantially with the examples mentioned most readily when people are asked to name emotions (Fehr & Russell, 1984), with the emotions children learn to name first (Bretherton & Beeghly, 1982), and with what theorists have called basic or primary emotions. This article reports two studies, one exploring the hierarchical organization of emotion concepts and one specifying the prototypes, or scripts, of five basic emotions, and it shows how the prototype approach might be used in the future to investigate the processing of information about emotional events, cross-cultural differences in emotion concepts, and the development of emotion knowledge.

Adult↗