Biomedical subjects
Publications and source records attributed to M O'Brien.
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.
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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.
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.
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.
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.
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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.
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.
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.
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.
A 22-year-old man presented with multiple raised erythematous skin lesions, pyrexia and epistaxis. A diagnosis of common acute lymphoblastic leukaemia (C-ALL) was made by morphological, cytochemical, immunological and cytogenetic examination of peripheral blood and bone marrow. Biopsy of the skin revealed leukaemic infiltration by similar cells.
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.
Instrumentation designed for stabilization and correction of spinal deformities must limit the amount of motion in flexion and extension. In flexion or extension, the vertebral bodies move about a specific point called the instantaneous axis of rotation. The ability of the implant to limit this motion is a function of its relation to the axis of rotation of the spine. The goal of this study was threefold: 1) to define the instantaneous axis of rotation of the spine in flexion and extension; 2) to study the effect of the loss of the three columns of the spine on the location of the instantaneous axis of rotation; and 3) to determine how the above parameters relate to the choice of anterior or posterior instrumentation. Ten human cadaver spines were subjected to compressive loads in flexion and extension. The columns of the spine were then destroyed in sequence at L3. The instantaneous axis of rotation for each vertebral body was found by the method of Reuleaux, and the effect of the compromise of the columns on the location of the instantaneous axis of rotation was noted. Understanding the exact location of the instantaneous axis of rotation after a specific injury would allow the clinician to objectively choose the best surgical approach and the appropriate instrumentation.
A retrospective study of 460 single-gestation infants in breech position was conducted at the University of Colorado Medical Center to assess the impact of a policy for the selection of cases for vaginal delivery. Among infants weighing more than 2,500 grams, there was an increase in the cesarean section rate from 13% to 54%, with an associated increase in maternal morbidity from 7% to 15%. This occurred with no significant reduction in adverse perinatal outcome. However, a case-by-case review suggests that more frequent and timely cesarean sections would have further reduced perinatal morbidity and deaths among term infants. Among the infants weighing 2,500 grams or less there was an increase in cesarean births from 5% to 55% following the introduction of the strict criteria for vaginal delivery. Among the infants weighing 1,501 to 2,500 grams there was no significant difference in survival between the cesarean and vaginally delivered patients. Although infants weighing 501 to 1,500 grams delivered by cesarean section survived more frequently than did those delivered vaginally, the differences in perinatal deaths may have been due to a higher birth weight in the cesarean-delivered infants or an over-all improvement in neonatal intensive care for infants of very low birth weight.
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We are isoelectric focusing small amounts of tissues placed directly on electroendosmosis-free agarose gels instead of using the saline extracts of tissue homogenates. More numerous proteins are extracted during isoelectric focusing of the solid tissues than present in the same tissues.
We report clinical, morphological and surface marker studies on seven patients with the common type of chronic lymphocytic leukaemia (CLL) whose disease underwent an insidious though progressive change in character with increasing refractoriness to treatment. This transformation was accompanied by the appearance of a population of immature-appearing cells in the peripheral blood which resembled prolymphocytes, both at light and electron microscopy. The characteristic morphological feature was the presence of two distinct populations of cells, the typical CLL lymphocytes and the 'prolymphocytoid' cells. These cells retained the surface characteristics of CLL, i.e. the information of mouse RBC rosettes and sparse surface-bound immunoglobulin. This transformation can be distinguished by morphological and surface marker criteria from acute leukaemia occurring in CCL, Richter's syndrome and prolymphocytic leukaemia. The recognition of this group of CLL patients may add a new prognostic index to CLL and may help plan subsequent trials for the treatment of the disease.