Carbamate formation and the neurotoxicity of L-alpha amino acids.
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Amino Acids↗
Biomedical subjects
P O'Brien
Publications and source records attributed to P O'Brien.
Hodgkin's disease of the liver; prognosis and possible indications for radiotherapy.
A retrospective analysis of 56 patients presenting with Hodgkin's disease involving the liver between 1970 and 1984 revealed a 10-year survival probability of 44%. The actuarial 10-year continuous progression free survival was 42%. Presentation variables predicting for relapse in the liver included hepatomegaly (P less than 0.025) or focal lesions on isotope, ultrasound or CT scan (P less than 0.01). These factors may define a context for investigation of adjuvant hepatic irradiation following chemotherapy.
Antineoplastic Combined Chemotherapy Protocols↗
Current status of radiosurgery for arteriovenous malformations.
Cerebral arteriovenous malformations (AVM), regardless of the mode of discovery, have an annual risk of hemorrhage of approximately 4 percent. A progressive obliterative vasculitis culminating in the occlusion of an AVM may be induced by the administration of radiation doses of approximately 20 Gy given in a single fraction. The process takes about two years and occlusion occurs in approximately 80% of patients so treated. Such a dose may be accurately administered to AVMs up to 3 cm in diameter with very little radiation imparted to the adjacent brain by means of multiple highly collimated radially arranged cobalt sources (the Gamma Knife) or by means of a modified linear accelerator turned through an arc or arcs with the target AVM as the centre of rotation. The Gamma Knife and the modified linear accelerator have nearly equal accuracy. Recent experience with modified linear accelerators indicates efficacy equal to the Gamma Knife. Both devices are effective treatment for small AVMs but the cost of modifying a pre-existing linear accelerator is only a few percent of the acquisition and installation costs of the Gamma Knife.
Evaluation Studies as Topic↗
Relationship between tissue selectivity and lipophilicity for inhibitors of HMG-CoA reductase.
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Animals↗
Non-Hodgkin's lymphoma presenting with extradural spinal cord compression: functional outcome and survival.
Between 1971 and 1988, 20 patients with previously undiagnosed non-Hodgkin's lymphoma (NHL), of intermediate or high grade histology presented with extradural spinal cord compression. All had decompressive surgery. The first treatment after surgery was chemotherapy in nine and radiotherapy in 11 patients. At presentation 15% were ambulant and this improved to 55% after surgery; urinary continence improved from 30 to 80%. Mobility and sphincter control remained unchanged, regardless of subsequent therapy. Chemotherapy as the initial treatment modality after surgery, either alone or in combination with radiotherapy, did not jeopardise functional outcome. Mobility after surgery was an independent prognostic factor for survival, when corrected for age and stage at presentation (P = 0.04). The treatment of intermediate and high grade NHL presenting with spinal cord compression should be based on histology, extent of disease and age, as with other sites of presentation, but should also take into consideration the prognostic importance of post-surgical mobility.
Adolescent↗
Studies of the binding of chromium(III) complexes to phosphate groups of adenosine triphosphate.
The binding of a number of chromium complexes to ATP has been studied by 31P NMR spectroscopy. The results are consistent with the formation of outer-sphere complexes between ATP and the chromium species. The magnitude of the binding constant has been determined as approximately 500 mol-1 dm3 (pH = 7.00) for the interaction of trisethylenediamine chromium(III) with ATP. Under our experimental conditions no NMR signals are observed from complexes in which chromium(III) is bound directly to the phosphate groups of ATP. The relative stability of the inner sphere complexes of chromium(III) and glutathione or ATP is probably not a significant factor in determining the toxicity of chromium(III) complexes.
Adenosine Triphosphate↗
The reduction of chromate is a prerequisite of chromium binding to cell nuclei.
Isolated calf thymus nuclei bound a chromium(III) glutathione complex in a time-dependent manner. In contrast chromium(VI) (sodium chromate) did not bind. However, when chromate was incubated with the nuclei in the presence of glutathione, chromium adducts were detected. These observations indicate that the reduction of chromate, by a reducing agent such as glutathione, is a prerequisite for the generation of bonds between the metal and constituents of the cell nuclei in vitro. Chromium adducts with nuclei are probably one cause of DNA lesions and mutations.
Animals↗
Whole brain radiation.
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Brain Neoplasms↗
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↗
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↗
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↗
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↗
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↗
Institutional review boards and quality assurance activities.
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Humans↗
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↗
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↗
Unique interventions for child inpatient psychiatry.
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Adolescent↗
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↗