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Biomedical subjects

P O'Brien

Publications and source records attributed to P O'Brien.

At least 109 records · Page 6Linked to original sources
PubMed1991

The prevalence of hearing impairment amongst Maori schoolchildren.

A survey of hearing amongst a population of Maori schoolchildren in the eastern North Island of New Zealand has demonstrated a high prevalence of hearing impairment. Out of 194 children undergoing audiometry an impairment of 20 dB or greater at 0.5, 1.2 and 4 kHz was found in the worse hearing ear in 29% and in the better hearing ear in 12%. Comparison with a similar survey done in the same valley in 1977 revealed an apparent reduction in the prevalence of hearing loss and the prevalence of otitis media. This improvement appears to be due to a reduced prevalence of otitis media. An unexpected finding was that at least 2% of the children had a bilateral sensorineural hearing impairment.

Adolescent↗
PubMed1991

Assessment of nutrient intake in association with weight loss after gastric restrictive procedures for morbid obesity.

Postoperative nutrient intakes were examined in patients who were losing weight in an early period following gastric restrictive surgery for morbid obesity (3 to 6 months post-surgery), and patients whose reduced weight was relatively stable at 1 to 2 years post-surgery. In association with weight loss, patients showed increased physical activity and reduced energy intakes which were frequently less than the Recommended Daily Intakes (RDI), particularly in the early period. Protein intake was also below recommended levels in the two post-operative phases. The intakes of iron, folate and calcium were below the recommended levels in the early postoperative phase. The intakes of iron and folate were also below recommended levels in the late postoperative phase. The study indicates the potential for deficiencies of iron, folate and calcium after gastric restrictive surgery and supports the importance of careful and prolonged follow-up of these patients, with particular attention to nutritional status.

Adult↗
PubMed1991

Myocardial biochemical and hemodynamic adaptations to chronic tachycardia.

The purpose was to determine the biochemical and hemodynamic adaptations of the myocardium to chronic tachycardia. Cardiac pacemakers were implanted in Yorkshire pigs and set at a rate of 180 beats/min for a period of 35-42 days. Animals were then anesthetized with pentobarbital sodium. Myocardial blood flow and hemodynamics were determined at three different heart rates (i.e., 120, 180, and 220 beats/min). Tissue samples were then taken for microsphere and biochemical analyses. Chronically paced hearts maintained better cardiac function and had consistently higher left ventricular blood flow with a higher endocardial-to-epicardial ratio. The activities of citrate synthase and 3-hydroxyacyl-CoA dehydrogenase were 23 and 45% greater in the paced hearts, respectively. The sarcoplasmic reticulum adenosinetriphosphatase activity was 55% greater in the paced hearts, whereas the myosin adenosinetriphosphatase was the same as in the control hearts. Polyacrylamide gels of the ventricular myosin isoforms showed only the V3 type to be present in both the control and paced hearts. These findings show that the heart of a large mammal adapts to chronic tachycardia (i.e., 180 beats/min) by elevating the aerobic and calcium-sequestering capacities without altering its myosin type.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1991

Competitive particle concentration fluorescence immunoassay for measuring 5,10-dideaza-5,6,7,8-tetrahydrofolic acid (lometrexol) in serum.

A competitive particle concentration fluorescence immunoassay (PCFIA) is described for measuring 5,10-dideaza-5,6,7,8-tetrahydrofolic acid (lometrexol; Lilly) in human serum. b-Phycoerythrin-labeled lometrexol competes with free lometrexol for binding to a limiting concentration of lometrexol-specific antibodies immobilized by a second antibody to submicrometer-diameter polystyrene particles in specially designed 96-well plates. Reaction particles are washed and concentrated onto filter membranes in the wells of the plates and the fluorescence is measured at 575 nm. The method, including sample preparation and data reduction, is automated and can be completed in less than 2 h. The assay has a standard curve maximum measurable concentration of 1000 micrograms/L and a minimum detectable concentration of 0.1 microgram/L. Analytical recovery of lometrexol in serum is quantitative at concentrations greater than 1 micrograms/L. Intra- and interassay coefficients of variation at 50 micrograms/L in serum are 7.1% (n = 9) and 7.5% (n = 33), respectively. The cross-reactivity of naturally occurring folates, folic acid analogs, and the anti-cancer agent methotrexate is minimal. We report the use of the PCFIA during Phase I clinical studies designed to evaluate the pharmacokinetics of lomextrexol after intravenous administration to cancer patients.

Adult↗
PubMed1991

Disposition of cerebral metastases from malignant melanoma: implications for radiosurgery.

Radiosurgery is becoming more generally available and indications for its use continue to be defined. Cerebral metastases from malignant melanoma are often treated with whole-brain irradiation, but with limited benefit. Innovative treatments, such as radiosurgery, make possible the delivery of doses of radiation that are higher than usual. To determine how many patients might be candidates for radiosurgery, a retrospective analysis of computed tomographic brain scans performed on 41 patients with cerebral metastases from malignant melanoma was undertaken. One-third of these patients were found to have cerebral metastases amenable to a radiosurgical approach, as illustrated radiation dose-volume histograms. Patient and tumor characteristics suggest that this series is represent with cerebral metastases from malignant melanoma. The implications of radiosurgery for normal tissue radiation tolerance and its effects on melanoma are discussed.

Adult↗
PubMed1990

Pseudomonas colonization in cystic fibrosis: lack of correlation with secretion of ABO blood group antigens.

In cystic fibrosis, a majority of patients develop persistent lifelong respiratory tract colonisation with pseudomonas aeruginosa while a minority do not appear to become colonised. There is some evidence that non-secretion of ABO Blood Group antigens into body secretions is a marker for susceptibility to certain gram negative infections. Therefore, we studied 47 adult patients with cystic fibrosis to identify an association, if any, between secretor status and the presence or absence of pseudomonas aeruginosa in their sputum. Overall, we found no difference between the prevalence of non-secretors in our patient group and in the normal population. Furthermore, there was no association between secretor status and presence or absence of pseudomonas aeruginosa in sputum. We conclude that secretor status is unlikely to play a major role in susceptibility to pseudomonas aeruginosa infection in patients with cystic fibrosis.

ABO Blood-Group System↗
PubMed1990

Psychosocial and physical activity changes after gastric restrictive procedures for morbid obesity.

Gastric restrictive procedures for morbid obesity are frequently performed to reduce problems arising from the physical limitations and social isolation of massive obesity. Numerous reports have described changes in weight after gastric restrictive operations, yet few studies have documented changes in the secondary effects of obesity. This report deals with changes in psychosocial status and physical activity occurring in 240 patients who remained in the study 3 years after surgery. These patients were members of a group of 310 patients who were entered into a prospective randomized trial to assess the relative benefits of three forms of gastric restrictive procedure. Prior to operation, and at yearly intervals after operation, the physical activities and psychosocial status of each patient was assessed by a standardized semi-structured interview. At the time of the three-year interview the median weight loss for these patients was 29.5 kg which represents 53% of excess weight lost. This weight loss was associated with a marked reduction in the amount of food eaten. There was a significant increase in the number of patients smoking more than 20 cigarettes a day and a mild increase in alcohol intake. There were significant improvements in the level of self-image and state of happiness. The social lives and sex lives of the majority of patients were improved and a significantly greater number of patients reported being in a stable emotional relationship at 3 years after operation than did so pre-operatively. There was a marked increase in the number of patients in full-time or part-time employment from 38% prior to surgery to 60% at 3 years after operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

The child following the Fontan procedure: nursing strategies.

The underlying principle of the Fontan procedure, perfusing the lungs without benefit of a ventricular pump, has been reinforced by its successful application in many children with complex cardiac anomalies involving only one functional ventricle. Several different techniques that direct systemic venous return through the right atrium directly to the pulmonary arteries can be used. By separating the pulmonary and systemic circulations, reducing ventricular volume overload, and relieving cyanosis, improved cardiac function and hemodynamics can be achieved. This article reviews the surgical techniques, perioperative nursing care with particular attention to the assessment, and management of systemic venous hypertension and the long-term outlook for these children. The collaboration of physicians and critical care nurses in the postoperative care of these children and their families is vital to a successful outcome.

Cardiac Surgical Procedures↗
PubMed1990

Micro-organisms as fertilizers and pest control agents in agricultural crops.

Micro-organisms can potentially supplement or replace the use of chemical fertilizers and pesticides in many agricultural cropping systems. Their increased use may reduce the need for nitrogen and phosphorus fertilizers, particularly in legume and cereal crops, and provide a more ecologically sound method of controlling pests and phytopathogens. Recombinant DNA technology offers the potential to extend and improve these applications. However, genetically modified micro-organisms may occasionally themselves pose environmental risks. Model ecosystems such as intact soil-core microcosms may be useful for both testing efficacy and evaluating environmental risk prior to proceeding with field trials.

Bacteria↗
PubMed1990

Metastatic malignant melanoma in pregnancy.

A 29 year old expectant mother was critically ill at 27 weeks gestation with disseminated metastatic malignant melanoma and was treated with dacarbazine. A dramatic remission was induced and at 38 weeks gestation she went into labour spontaneously and delivered a healthy infant. She relapsed and died eight weeks post partum. This is the first reported use of dacarbazine in pregnancy.

Dacarbazine↗
PubMed1990

Orthotopic heart transplantation for complex congenital heart disease.

Orthotopic heart transplantation has become standard therapy for end-stage cardiomyopathy in children and adults, but there has been much less experience with transplantation for complex congenital heart disease. In this report experience with orthotopic transplantation in seven children with various forms of complex congenital heart disease is reviewed. Diagnoses included hypoplastic left heart syndrome in two (after stage I palliation), left ventricular diverticulum in one, single ventricle in two (dextrocardia, atrial situs inversus, and total anomalous pulmonary venous return in one patient and post-Fontan repair in the second), D-transposition of the great arteries and ventricular septal defect (post-Senning repair and ventricular septal defect closure) in one, and Ebstein's anomaly with biventricular dysplasia in one. Six of the seven were hospital survivors and there has been one late death at 2 1/3 years. Modifications of the standard operative technique to fit the anatomic variations in these defects are reviewed.

Adolescent↗
PubMed1989

The interaction of beta-N-methylamino-L-alanine with bicarbonate: an 1H-NMR study.

The mode of action of the neurotoxic, non-protein amino acid beta-N-methylamino-L-alanine (L-BMAA) is unknown. We have shown, using 1H-NMR spectroscopy, that L-BMAA forms a stable adduct with bicarbonate (probably a carbamate). The properties of this adduct may explain the observation that L-BMAA and N-methyl-D-aspartic acid appear to act at the same central nervous system receptors.

Amino Acids, Diamino↗
PubMed1989

Otitis media and hearing loss in the children of the Ruatoki valley: a continuing public health problem.

A longitudinal survey of ear disease using repeated otomicroscopy has demonstrated cases of persistent middle ear effusion, cholesteatoma and perforation in a group of 275 Maori children. The hearing of 194 of the children was assessed, and 25% of them were found to have a hearing loss. It is concluded a public health problem exists with these children. Improved detection and treatment of ear disease and hearing loss in this population is recommended.

Acoustic Impedance Tests↗
PubMed1989

Single-dose antibiotic prophylaxis in contaminated abdominal surgery.

Although perioperative antibiotic cover reduces the incidence of septic complications associated with abdominal surgery, the optimum duration of antibiotic exposure is open to question. This clinical trial compared the efficacy of a single dose of moxalactam (1 g intravenously) with an extended course of moxalactam (1 g intravenously for eight doses) in 1027 patients undergoing contaminated abdominal surgery. The wound infection rate was 5.4% (28/519) for the single-dose schedule and 6.1% (31/508) for the extended-cover regimen (the respective 95% confidence intervals being 3.6% to 7.7% and 4.2% to 8.6%). Over 80% of all patients undergoing abdominal surgery during the period of study were entered into the trial. There was no significant difference in the incidence of other complications between the two groups under study. It is concluded that a single dose of moxalactam is as effective as a 48-hour course when attempting to prevent infection after contaminated abdominal surgery.

Biliary Tract Surgical Procedures↗
PubMed1989

Complexes of zinc, copper, and nickel with the nonprotein amino acid L-alpha-amino-beta-methylaminopropionic acid: a naturally occurring neurotoxin.

The non-protein amino acid L-alpha-amino-beta-methylaminopropionic acid (L-MeDAP) causes motor neuron dysfunction in macaques. The amino acid is a potent chelator of divalent metal ions such as copper and zinc. Binding constants nickel(II) for copper(II) and zinc(II) with L-MeDAP have been measured. Some copper(II) complexes of L-MeDAP have been synthesized and characterized by their electronic, infrared, and epr spectra. These results are used to comment on the possibility that metal ion complexation in the central nervous system is involved in the expression of the meurotoxicity of L-MeDAP.

Amino Acids, Diamino↗
PubMed1989

Generation of PM2 DNA breaks in the course of reduction of chromium(VI) by glutathione.

The carcinogen chromate is efficiently taken up and reduced to chromium(III) compounds by various biological systems. To test the possible DNA damage induced in the course of chromium(VI) reduction, we used a combination of chromate with the reductant glutathione (GSH) as well as a green complex of chromium(V), which is formed in the reaction of chromate with GSH. The combination of chromate and glutathione was found to cause single-strand breaks in supercoiled circular DNA of the bacteriophage PM2. The green chromium(V) complex Na4(GSH)4Cr(V).8H2O, prepared from chromate and glutathione, also cleaved supercoiled PM2 DNA. No DNA-degrading effects were observed with either chromate or the final product of the reaction with GSH, a purple anionic chromium(III) GSH complex. The nature of the buffering agents revealed a strong influence on the extent of DNA strand breaks produced by chromate and GSH. A variation of the GSH concentration in the reaction with chromate and PM2 DNA, performed in sodium phosphate-buffered solutions showed an initial increase in the number of strand breaks at GSH concentrations up to 1 mM followed by a decline at higher GSH concentrations. Since neither chromate, when administered individually, nor the final product of chromium(VI) reduction, the purple chromium(III) GSH complex, produced any detectable DNA cleavage, the critical steps leading to DNA strand breaks occur in the course of the conversion of chromium(VI) to chromium(III) by GSH, the most abundant intracellular low molecular thiol. Moreover, the demonstration that DNA cleavage is induced in the presence of the chromium(V) complex identifies chromium(V) as the oxidation state of the metal, which is involved in the steps leading to DNA-damaging effects of chromate.

Bacteriophages↗