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Biomedical subjects

M O'Brien

Publications and source records attributed to M O'Brien.

At least 199 records · Page 11Linked to original sources
PubMed1993

Low dose rate teletherapy and tumour response.

Tumour responses in 25 patients with locally advanced head and neck cancer, treated on an experimental fractionated low dose rate (FLDR) teletherapy program are reported. Treatment was given at dose rates ranging from 1.8 to 3 Gy/h to a range of total doses from 32-38 Gy, with palliative intent. The total doses delivered have been predicted by the linear quadratic formula to be equivalent to 33-41 Gy using conventionally fractionated high dose rate treatment, in terms of acute normal tissue effects. A complete response rate (no visible or palpable disease 2 months after treatment) was observed in 28% of cases. Analysis of these response rates suggests that the linear quadratic formula may underestimate the anti-tumour effect of FLDR teletherapy at the various dose rates and total dose permutations in this study.

Carcinoma, Squamous Cell↗
PubMed1993

Parent preparation for the NICU-to-home transition: staff and parent perceptions.

Thirty-four nurses who were employed more than 20 hr per week in a neonatal intensive care unit (NICU) at a midwestern teaching hospital participated in a survey on discharge teaching. The survey consisted of 43 topics on which parents may or may not receive instruction prior to their baby's discharge from the NICU. For each topic, nurses were asked how important the topic is for parents to learn about prior to discharge, whether parents in the NICU are currently receiving instruction on the topic, and who among the NICU staff is responsible for instruction on the topic. Data obtained from this survey were compared to data obtained from a similar survey conducted 18 months previously with parents in the same NICU. Nurses rated the majority of topics in the survey as being very important for parents to learn about prior to their baby's discharge. For many of the items, a significant discrepancy existed between the percentage of nurses reporting the topics that were routinely taught and the percentage of parents who actually recalled learning about the topics. Suggestions on ways to improve the effectiveness of discharge teaching are provided.

Attitude of Health Personnel↗
PubMed1993

Biomechanics of the spine in sports.

An understanding of spinal mechanics is necessary for the treatment of athletic injuries. Recognizing and isolating the mechanism of injury through noninvasive techniques will lead to specific treatment for that injury. Because the prevention of physical injury is the goal of all health care professionals, the authors hope that the information will be helpful.

Athletic Injuries↗
PubMed1993

Whiplash and temporomandibular joint dysfunction.

This article examines the relationship between Temporomandibular joint dysfunction and rear-end (whiplash) motor vehicle accidents. The clinical and statistical evidence relating TMJ damage to whiplash is reviewed. The sequence of events regarding the head, neck and jaw movements which occur in these accidents is considered. The jaw movements are discussed in detail. An analysis of the forces resulting from these movements indicates that tensile, compressive and shear forces occur which challenge the integrity of the soft tissues of the Temporomandibular joint. An overview of the mechanisms whereby damage may occur is considered. A more detailed analysis of these mechanisms will be dealt with in further articles, to evaluate the precise magnitude and direction of forces in all phases of the accident.

Accidents, Traffic↗
PubMed1992

Necrotizing cellulitis caused by Legionella micdadei.

Legionella micdadei is primarily considered a pathogen of the pulmonary tract of immunocompromised patients, the majority of whom have been renal transplant recipients. We report the case of a necrotizing soft tissue infection in a cadaveric renal transplant recipient resulting in amputation of the left arm. Only one other extrathoracic bacteriologically documented L. micdadei infection has been reported in the literature.

Adult↗
PubMed1992

Instantaneous axis of rotation as a function of the three columns of the spine.

A knowledge of the rotatory motion of the vertebral bodies is needed to understand the normal biomechanical behavior of the spine. The aims of this investigation were 1) to define the instantaneous axis of rotation of the lumbar spine in rotation; and 2) to study the effect of the loss of the anulus, facet joints, and ligamentous structures on the location of the instantaneous axis of rotation. The instantaneous axis of rotation was found in 10 human cadaver thoracolumbar spines by the method of Reuleaux from superimposed serial photographs. Long-segment specimens were tested to minimize the effect of the imposed axis of the testing device. The instantaneous axis of rotation was consistently posterior to the anulus in the intact spine. With isolated destruction of the columns of the spine, the instantaneous axis of rotation migrated to the remaining intact structures. Anterior releases enhance derotation by removing the primary rotatory stabilizer. Ultimate control of a rotatory deformity or instability lies in the recognition that the anterior structures have a mechanical advantage in resisting torsion.

Biomechanical Phenomena↗
PubMed1992

A randomized trial of late reperfusion therapy for acute myocardial infarction. Thrombolysis and Angioplasty in Myocardial Infarction-6 Study Group.

BACKGROUND: Experimental and observational clinical studies of acute coronary occlusion have suggested that late reperfusion prevents infarct expansion and facilitates myocardial healing. The purpose of this trial was to assess whether infarct vessel patency could be achieved in late-entry patients and what benefit, if any, can be demonstrated. METHODS AND RESULTS: In a double-blind fashion, 197 patients with 6 to 24 hours of symptoms and ECG ST elevation were randomly assigned to tissue-type plasminogen activator (100 mg over 2 hours) or placebo. Coronary angiography within 24 hours was used to determine infarct vessel patency status. Patients with infarct-related occluded arteries were then eligible for a second randomization to either angioplasty (34 patients) or no angioplasty (37 patients). Ventricular function and cavity size were reassessed at 1 month by gated blood pool scintigraphy and at 6 months by repeat cardiac catheterization. The primary end point, infarct vessel patency, was 65% for plasminogen activator patients compared with 27% in the placebo group (p less than 0.0001). There were no differences between these groups in ejection fraction or infarct zone regional wall motion at 1 or 6 months. At 6 months, infarct vessel patency was 59% in both groups. In the placebo group, there was a significant increase in end-diastolic volume from acute phase of 127 ml to 159 ml at 6-month follow-up (p = 0.006) but no increase in cavity size for the plasminogen activator group patients. Coronary angioplasty was associated with an initial 81% recanalization success and improved ventricular function at 1 month, but by late follow-up no advantage could be demonstrated for this procedure, and there was a 38% spontaneous recanalization rate in the patients assigned to no angioplasty. CONCLUSIONS: The study demonstrates that it is possible to achieve infarct vessel recanalization in the majority of late-entry patients with either thrombolytic therapy or angioplasty. Thrombolytic intervention had a favorable effect on prevention of cavity dilatation and left ventricular remodeling, but there are no late benefits on systolic function after thrombolysis or coronary angioplasty. The conclusions concerning overall potential benefit of applying late reperfusion therapy will require data from large-scale trials designed to assess mortality reduction.

Angioplasty, Balloon, Coronary↗
PubMed1992

Informatics Workup.

We introduce the concept of a Medical Informatics Workup performed by fourth year medical students working in a busy inner-city Emergency Room. These students use portable computers (Macintosh PowerBook 170s connected to a removable cartridge hard drive and CD-ROM drive) to do the patient workups. The PowerBook 170 contains the automated medical record entry software (IMR-E), five expert system software packages, and a program that allows the PowerBook to emulate a PC-compatible computer. With this configuration the student has a portable system that allows for the creation of a computerized medical record at the patient's bedside, along with the ability to analyze the data and generate a list of differential diagnoses.

Angina Pectoris↗
PubMed1992

Functional anatomy and physiology of tendons.

Tendons vary in type, shape, and size. The anatomy, histology, and physiology of tendons are described in this article, with particular reference to those tendons that are vulnerable in sports medicine.

Aging↗
PubMed1991

Effects of aminoguanidine on pre- and post-irradiation regional cerebral blood flow, systemic blood pressure and plasma histamine levels in the primate.

Exposure to ionizing radiation causes hypotension, cerebral ischemia and release of histamine (HA). To investigate the relationship among these three responses, rhesus monkeys (Macaca mulatta) received aminoguanidine (AG) (1 mg/kg), then were given either 50 Gy whole-body irradiation or sham-irradiation. Monkeys receiving AG had lower mean arterial blood pressure (MABP) than saline-treated controls. Compared to controls, rCBF was lower in irradiated monkeys but pre-treatment with AG did not influence this effect. Among untreated, irradiated monkeys, HA levels were increased only at two minutes post-irradiation, but among AG-treated, irradiated monkeys, HA levels were higher at all times postirradiation. Radiation-induced release of HA may be associated with radiation-induced hypotension and reduced rCBF, but failure of AG to alter rCBF suggests that released HA may not be the sole mediator of these effects. Because elevations in plasma HA are probably due to HA derived from degranulation of mast cells, release of other bioactive substances from mast cells may also influence these cardiovascular effects. Surprisingly, in sham-irradiated monkeys, AG alone had a slight but significant hypotensive effect.

Animals↗
PubMed1991

Randomized controlled trial of prophylactic rifampin for peritoneal dialysis-related infections.

Staphylococcal infections are a major cause of catheter infections and peritonitis in peritoneal dialysis patients. Since catheter-related infections are associated with nasal carriage of Staphylococcus aureus in this population, we studied the effect of intermittent rifampin, an antibiotic known to decrease S aureus nasal carriage, on catheter-related infections and peritonitis. We randomly assigned 64 patients to receive either rifampin 300 mg twice daily for 5 days every 3 months or no treatment. The rifampin-treated patients had a significant delay in time to first catheter-related infection (P less than 0.015) and significantly fewer catheter-related infections overall (P less than 0.001). The catheter-related infection rate in rifampin-treated patients was .26 per patient-year versus .93 per patient-year in untreated patients. Multivariate analysis defined baseline colonization of nares or catheter exit-site and prior renal transplant as risk factors for catheter-related infections. There was no significant difference in peritonitis rates between groups, although the trend was for a delayed time to first episodes and fewer episodes in rifampin-treated patients. Adverse effects necessitated withdrawal of rifampin in four patients. We conclude that intermittent rifampin administration is effective in decreasing catheter-related infections in a peritoneal dialysis population.

Adult↗
PubMed1991

Mothers' and sons' cognitive and emotional reactions to stimulated marital and family conflict.

This study examined cognitive and emotional reactions to family discussions as experienced by sons and mothers from homes with physically aggressive (PA), verbally aggressive (VA), and low-conflict (LC) marital relationships. Boys of PA couples demonstrated more self-interference, self-distraction, and arousal and less criticism than did other sons in reaction to stimulated parental conflict. Boys of LC parents were more optimistic about family conflict and articulated more ideas concerning family structure and how conflict "should" proceed than did other sons. PA mothers made more positive evaluations and offered more autocratic suggestions than did VA mothers. Also, LC mothers, compared with both conflictual groups, made more democratic statements in response to low-conflict situations. These results indicate that marital conflict experienced in the home may influence sons' and mothers' appraisals of family and marital interactions.

Adaptation, Psychological↗
PubMed1991

Quantitative fluorometric assay for rapid enzymatic characterization of Bifidobacterium longum and related bifidobacteria.

The quantitative, semi-automated assay described here is an alternative characterization method allowing for highly sensitive and specific detection of bifidobacterial enzymes. Twenty strains of Bifidobacterium longum, including the type strain ATCC 15707, and type strains of 15 other Bifidobacterium species were enzymatically characterized using 20 4-methylumbelliferyl conjugated substrates. Enzyme activities were determined by directly measuring the intensity of fluorescence derived from 4-methylumbelliferone, a fluorescent metabolic by-product. For this method, a Titertek Fluoroskan II fluorometer was used. Enzymes included glycosidases, an esterase, phosphatase, sulphatase, and neuraminidase. B. longum showed strong activity (greater than 1,000 absolute fluorescence units, afu) for alpha-L-Arabinopyranosidase and alpha-L-Arabinofuranosidase, beta-D-Fucosidase, alpha- and beta-D-Galactosidase, alpha-D-Glucosidase, and alpha-D-Mannosidase. No activity (less than or equal to 50 afu) was observed for beta-D-Cellobiosidase, alpha- and beta-L-Fucosidase, beta-D-Glucuronidase, beta-D-Mannosidase, Neuraminidase and Sulphatase. Enzymatic activity profiles in other bifidobacteria were different according to the species. This assay is simple and rapid (6 hr). Special cultural requirements are unnecessary. Results are objective and quantitative. This assay may be a useful tool for bifidobacterial taxonomy.

Adolescent↗
PubMed1991

Interspersed requests: a nonaversive procedure for reducing aggression and self-injury during instruction.

Interspersed requests are simple commands, with a high likelihood of being followed correctly, that are interspersed among instructional trials to increase the probability that a learner will attempt to perform new or difficult tasks without engaging in aggression or self-injurious behavior. This report presents two assessments of the effect of interspersed requests on aggression and self-injury during instruction. The participants were individuals with severe mental retardation who used aggression and self-injury to avoid difficult instructional situations. Results from both studies indicate that interspersed requests were effective at increasing the responsiveness of the learners to instructions and reducing levels of aggression and self-injury.

Activities of Daily Living↗