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Biomedical subjects

P O'Brien

Publications and source records attributed to P O'Brien.

At least 37 records · Page 2Linked to original sources
PubMed1995

Oxygen saturations during breast and bottle feedings in infants with congenital heart disease.

Bottle feeding is commonly advised for infants with congenital heart disease (CHD) based on the belief that breast feeding is too difficult for them. However, studies of preterm infants have shown that greater cardiorespiratory effort occurs during bottle feeding than during breast feeding. The purpose of this study is to determine if there is a relationship between feeding method (breast vs. bottle) and oxygen saturations (SaO2) in infants with CHD. In a correlational design, pulse oximetry measured SaO2 during one breast and one bottle feeding in each of 7 infants with CHD. SaO2 during breast feeding is significantly different from SaO2 during bottle feeding (F = 59.72, p < .0001). SaO2 during breast feeding is higher on average and less variable (M = 96.3%, SD = 2.2) than SaO2 during bottle feedings (M = 92.5%, SD = 6.9), indicating that there is less cardiorespiratory stress with breast feeding. None of the infants desaturated (SaO2 < 90%) during breast feedings, whereas four infants desaturated during bottle feedings.

Bottle Feeding↗
PubMed1995

Dietary shifts and implications for US agriculture.

Changes to healthier dietary patterns similar to those of traditional Mediterranean diets or those of the US government's dietary guidelines and food guide pyramid would require significant changes in American agricultural practices. The volume, mix, production, and marketing of agricultural commodities would need to be modified. Because differences between actual and recommended intakes for major food groups are quite large and affect a broad range of products, adjustments in supply and demand could overshadow past experience in dealing with such changes. New food and agriculture policies may well be needed to ease and accelerate agricultural adjustments, to improve nutritional characteristics of popular foods, and to promote desirable changes in consumers' food choices.

Agriculture↗
PubMed1995

Soluble-binding proteins for docosahexaenoic acid are present in neural retina.

PURPOSE: To determine if soluble binding proteins (BP) for fatty acids (FA), particularly docosahexaenoic acid (DHA), could be identified in the cytosol of rat and bovine retinas under in vitro and in vivo conditions. METHODS: In vitro, cytosol fractions from normal bovine and rat retinas were delipidated and incubated with [14C]-DHA with or without a number of competing fatty acids. After crosslinking bound FA to BP, the proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and radioactivity determined in each fraction. For in vivo experiments, rats received [14C]-DHA by gavage. At selected periods after ingestion, retinas were collected and cytosolic fractions were prepared from each. These were crosslinked and subjected to SDS-PAGE, and radioactivity was determined in each fraction. RESULTS: In vitro, several peaks of radioactivity (approximately 13, 20, 32, 43-45, 50, 63, and 94-105 kd) were found that exhibited [14C]-DHA binding. Relative specificity of binding was assessed by blocking of the [14C]-DHA binding with unlabeled DHA and by competition experiments with other FAs. After in vivo ingestion of [14C]-DHA, a large peak of radioactivity was observed at 43 kd by 4 hours. At 6 hours, this peak decreased and, after 24 hours, it approached baseline. CONCLUSIONS: These findings demonstrate that there is a discrete grouping of proteins in retinal cytosol capable of binding DHA and other FA. Although the identities of these proteins have yet to be determined, the group may include a member of the 12- to 15-kd group of small fatty acid binding proteins (FABP). In particular, a unique 43-kd binding peak could play a major role in the uptake, binding, or both of DHA by the retina in vivo.

Animals↗
PubMed1995

Current management of congestive heart failure in infants and children.

Although the general goals of therapy for the medical and nursing management of CHF in children have not changed in the last decade, advances have been made in understanding the unique characteristics of the neonatal heart and tailoring therapy to best support cardiac function (Table 6). In addition, strides have been made in manipulating the loading conditions of the ventricle to enhance cardiac output, which has fostered the development of new therapeutic agents and more aggressive treatment of these patients with improved outcomes. In situations in which the infant is unresponsive to therapy, surgical intervention is now done at an earlier age with good results. When surgery is not an option and the patient continues to deteriorate despite maximum medical management, mechanical support can be instituted as a bridge to transplantation.

Cardiotonic Agents↗
PubMed1994

General surgery.

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Breast Neoplasms↗
PubMed1994

Impairment, disability, and handicap in multiple sclerosis: a population-based study in Olmsted County, Minnesota.

We studied functional status of MS patients in a geographically based cohort in Olmsted County, Minnesota. The 162 definite MS patients who were alive and residing in the study area on December 1, 1991, constituted the MS prevalence disability cohort. We identified 179 cases of definite or probable MS, providing an overall sex- and age-adjusted prevalence rate of 167.5 per 100,000. Median duration of MS from onset was 15.4 years, and median age on prevalence date was 47.5 years. The Minimal Record of Disability for MS determined the degree of impairment, disability, and handicap of the entire cohort within 4 months of the prevalence date. The frequency of Expanded Disability Status Scale scores of the MS prevalence cohort showed a bimodal distribution with peaks at 1 and 6.5 (3.5 [1 to 9.5], median [range]). Approximately one-third of the cohort had marked paraparesis, paraplegia, or quadriplegia. One-fourth of all patients needed intermittent or almost constant catheterization for bladder dysfunction. Few patients (3.7%) reported severe decrease in mentation or dementia requiring supervision. Many patients (53.1%) were working full-time. Most patients (72.2%) maintained their usual financial standard without external support. There were no differences in level of impairment, disability, or handicap observed between the subgroup of 122 patients (75.3%) who are incident cases (onset of disease as residents of Olmsted County) compared with the entire prevalence cohort. This geographically based study of MS demonstrates that the functional status is more favorable than previously recognized.

Activities of Daily Living↗
PubMed1994

The generation of DNA single-strand breaks during the reduction of chromate by ascorbic acid and/or glutathione in vitro.

The potential role of iron and copper and the involvement of hydroxyl radicals in the DNA cleavage caused by chromate and glutathione (GSH) has been investigated. We have also studied the ability of chromate, on reaction with ascorbate as well as in mixed solutions of ascorbate and GSH, to cause DNA strand breaks. In both fully demetalated and conventional (i.e., metal contaminated) systems, chromate and GSH induced similar numbers of DNA strand breaks. This observation suggests that traces of iron or copper contaminating the reaction mixtures do not play a major role in the DNA cleavage caused by chromate and GSH. A series of hydroxyl radical scavengers exhibited a protective influence on the induction of DNA strand breaks. However, glucose and sucrose, both strong hydroxyl radical scavengers, showed no concentration-dependent inhibition of DNA cleavage. Competition kinetics studies yielded apparent rate constants that were not consistent with hydroxyl radicals being the species responsible for DNA strand breaks. Ascorbate in combination with chromate was also found to induce strand breaks in DNA; this damage could be attributed to reactive intermediates generated during the reduction. When mixed systems of ascorbate and GSH in the presence of chromate were investigated, there were clearly interactions between the two reductants.

Ascorbic Acid↗
PubMed1994

Chemical models important in understanding the ways in which chromate can damage DNA.

Chromate is an established human carcinogen. There have been many studies of the reactivity of chromate aimed at improving understanding of chromate toxicity. In the present paper a number of conclusions of these studies are reviewed and considered in the light of new results obtained in our laboratories. A number of hypotheses are considered; it is concluded, however, that it is impossible to reconcile the generation of strand breaks by chromate during its reduction by glutathione with any simple mechanism involving the generation of DNA lesions by free hydroxyl radicals. Kinetic, spin-trapping, and competition kinetic studies, based on a strand-breaking assay, are reported in support of this conclusion.

Animals↗
PubMed1994

Radiation and carboplatin combined-modality therapy in non-small cell lung cancer.

Previously untreated patients with stages I to IV, N0-3, M0 unresectable non-small cell lung cancer were randomized to arm I (conventional radiotherapy [RT], 60 Gy in 30 fractions over 6 weeks), arm II (accelerated RT, 60 Gy in 30 fractions over 3 weeks), arm III (conventional RT, as in arm I, plus carboplatin 70 mg/m2/d on days 1 to 5 during treatment weeks 1 and 5), or arm IV (accelerated RT, as in arm II, plus carboplatin 70 mg/m2/d on days 1 to 5 of week 1 only). An intensive analysis of toxicity in the first 92 patients entered revealed significantly more neutropenia (P < .0001) and thrombocytopenia (P = .004) in the combined-modality arms. Esophagitis was worse on arms II, III, and IV, but was more prolonged in the accelerated RT arms. Overall, however, the treatment on all study arms was well tolerated.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Chronic hypoxemia in children with cyanotic heart disease.

Hypoxemia, visible as cyanosis, is present in infants and children with congenital cardiac defects that result in arterial desaturation. Although many of these defects can be surgically repaired, some children remain cyanotic. Chronic cyanosis causes adaptive changes such as polycythemia and potentially damaging changes in other organ systems. This article reviews the assessment and management of patients with cyanotic congenital heart disease. The physiologic consequences and associated medical problems of chronic cyanosis are highlighted. Nursing implications in caring for cyanotic children and young adults are discussed.

Child↗
PubMed1993

Generation of substance P carbamate in neutral aqueous solution. Relevance to inflammatory joint diseases.

High-field proton (1H) nuclear magnetic resonance (NMR) spectroscopy has been employed to evaluate the formation of substance P carbamate in aqueous solution. Equilibration of substance P with physiologically relevant concentrations of bicarbonate (2.50 x 10(-2) mol.dm-3) at pH 7.00 generated a new multiplet signal centred at 4.13 ppm in its NMR spectrum, characteristic of the alpha-proton of peptide carbamate species. High-field 1H NMR spectroscopy also demonstrated that the model dipeptide, Arg-Gly, formed a carbamate in neutral aqueous solutions containing 2.50 x 10(-2) mol.dm-3 HCO3-. The physiological significance of these results is discussed in view of the central roles of vasoactive neuropeptides in human joint diseases and the hypercapnic environment of the inflamed rheumatoid joint.

Arthritis, Rheumatoid↗
PubMed1993

Recovery of contractile function of postischemic, reperfused myocardium: influence of 2,3-butanedione-2-monoxime.

Inhibition of mechanical activity during ischemia could improve recovery of stunned myocardium. In this study, the effect of 2,3-butanedione-2-monoxime (BDM), an agent that disrupts excitation-contraction coupling, on the time course of recovery of contractile function of postischemic reperfused myocardium was studied in open-chest anesthetized dogs. Ischemia was produced by occluding the left anterior descending coronary artery (LAD) for 15 mins. In separate experimental groups, during the occlusion period, 6 ml of either 100 mM BDM or drug vehicle (0.9% normal saline) was infused into the distal perfusion bed subjected to occlusion. Regional myocardial function (percentages of segment shortening % SS) was assessed by sonomicrometry. LAD occlusion resulted in similar degrees of dyskinesia in both experimental groups. Subsequent recovery of contractile function during reperfusion was evaluated for 3 h. In control experiments, segment shortening remained significantly (p < 0.05) decreased throughout the reperfusion period, returning to only 36.1 +/- 9.2% of the preocclusion value at 3 h postreperfusion. In BDM experiments, regional contractile function returned to 72.4 +/- 11.3% of the preocclusion value at 1 h of reperfusion. Rapid recovery was sustained throughout reperfusion. Regional stroke work area (RSWA) also demonstrated rapid sustained recovery of function after treatment with BDM. RSWA was significantly greater in BDM experiments as compared with control experiments at all times during the reperfusion period. These results demonstrate that selective intracoronary (i.c.) administration of BDM during ischemia markedly enhances postischemic recovery of contractile function. The underlying mechanism for this action may involve modulation of several aspects of impaired cellular function in postischemic tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Bacterial aerosol emission rates from municipal wastewater aeration tanks.

In this report we describe the results of a study conducted to determine the rates of bacterial aerosol emission from the surfaces of the aeration tanks of the Metropolitan Water Reclamation District of Greater Chicago John E. Egan Water Reclamation Plant. This study was accomplished by conducting test runs in which Andersen six-stage viable samplers were used to collect bacterial aerosol samples inside a walled tower positioned above an aeration tank liquid surface at the John E. Egan Water Reclamation Plant. The samples were analyzed for standard plate counts (SPC), total coliforms (TC), fecal coliforms, and fecal streptococci. Two methods of calculation were used to estimate the bacterial emission rate. The first method was a conventional stack emission rate calculation method in which the measured air concentration of bacteria was multiplied by the air flow rate emanating from the aeration tanks. The second method was a more empirical method in which an attempt was made to measure all of the bacteria emanating from an isolated area (0.37 m2) of the aeration tank surface over time. The data from six test runs were used to determine bacterial emission rates by both calculation methods. As determined by the conventional calculation method, the average SPC emission rate was 1.61 SPC/m2/s (range, 0.66 to 2.65 SPC/m2/s). As determined by the empirical calculation method, the average SPC emission rate was 2.18 SPC/m2/s (range, 1.25 to 2.66 SPC/m2/s). For TC, the average emission rate was 0.20 TC/m2/s (range, 0.02 to 0.40 TC/m2/s) when the conventional calculation method was used and 0.27 TC/m2/s (range, 0.04 to 0.53 TC/m2/s) when the empirical calculation method was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1993

Contracting to lower precaution status for child psychiatric inpatients.

1. Contracting will reduce high-risk precaution incidents. 2. Children are capable of understanding, writing, and adhering to contracting procedures. 3. Contracting performed according to established procedures that use specified criteria for advancement is effective. 4. Nurses should listen carefully and critically examine the child's statements, avoiding making inferences about the child's intentions.

Adolescent↗
PubMed1992

Regional redistribution of myocardial perfusion by UL-FS 49, a selective bradycardic agent.

The effects of UL-FS 49, a specific bradycardic agent, on systemic hemodynamics, regional myocardial function (sonomicrometry, percentage of segment shortening), and regional coronary blood flow (radioactive microspheres) were studied in open-chest, anesthetized dogs with severe left circumflex coronary artery (LCX) stenosis. UL-FS 49 was administered as two sequential bolus injections of 0.25 mg/kg. Heart rate decreased from 149 +/- 13 beats/min to 102 +/- 6 and 77 +/- 4 beats/min after 0.25 and 0.5 mg/kg cumulative doses of UL-FS 49, respectively. The reduction in heart rate was not associated with any significant change in left ventricular pressure or mean arterial pressure, left ventricular dp/dt, or coronary vascular resistance. Similarly no hemodynamic changes occurred with atrial pacing to the initial heart rate. Application of an LCX stenosis of sufficient severity to produce a 50% reduction in mean LCX blood flow (44 +/- 4 to 22 +/- 2 ml/min) resulted in a significant reduction in the percentage of segment shortening in the ischemic zone (9.8 +/- 1.6% to 6.5 +/- 1.1%). The percentage of segment shortening in the ischemic zone progressively improved to 8.4 +/- 1.2% and 9.4 +/- 0.5% after 0.25 and 0.5 mg/kg UL-FS 49, respectively. Subepicardial perfusion in the ischemic zone was decreased and subendocardial perfusion was increased after administration of UL-FS 49. Consequently the ischemic zone endocardial/epicardial ratio increased from 0.43 +/- 0.08 to 1.12 +/- 0.22 and 1.48 +/- 0.32 with low and high doses of UL-FS 49.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗