Biomedical subjects
D G Harris
Publications and source records attributed to D G Harris.
Making do not attempt resuscitation decisions: do doctors follow the guidelines?
When do not attempt resuscitation orders are contemplated, guidelines exist to outline standards for planning patient care and decision making. These guidelines may not always be fully followed as ethical issues arise which may prevent doctors from doing so.
Conserved fragments of transposable elements in intergenic regions: evidence for widespread recruitment of MIR- and L2-derived sequences within the mouse and human genomes.
We analysed the distribution of transposable elements (TEs) in 100 aligned pairs of orthologous intergenic regions from the mouse and human genomes. Within these regions, conserved segments of high similarity between the two species alternate with segments of low similarity. Identifiable TEs comprise 40-60% of segments of low similarity. Within such segments, a particular copy of a TE found in one species has no orthologue in the other. Overall, TEs comprise only approximately 20 % of conserved segments. However, TEs from two families, MIR and L2, are rather common within conserved segments. Statistical analysis of the distributions of TEs suggests that a majority of the MIR and L2 elements present in murine intergenic regions have human orthologues. These elements must have been present in the common ancestor of human and mouse and have remained under substantial negative selection that prevented their divergence beyond recognition. If so, recruitment of MIR- and L2-derived sequences to perform a function that increases host fitness is rather common, with at least two such events per host gene. The central part of the MIR consensus sequence is over-represented in conserved segments given its background frequency in the genome, suggesting that it is under the strongest selective constraint.
Myocardial abscess with contained rupture: successful repair.
Spontaneous rupture of the heart from myocardial abscess is a rare occurrence. Most cases of spontaneous cardiac rupture are due to myocardial infarction. We present a case of a contained rupture of the heart in a patient with staphylococcal septicemia. Although cultures from the pericardial space were negative the macroscopic and clinical picture was compatible with an abscess.
An unusual cause of nearly fatal hemoptysis.
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Hydatid cyst fistula into the aorta presenting with massive hemoptysis. Case report and literature review.
Hydatid involvement of the aorta is extremely uncommon. We present a case where a hydatid cyst of the lung eroded into the thoracic aorta, causing massive hemoptysis. Successful repair was performed by resection (including left lower lobectomy) and graft interposition.
Penetrating cardiac injuries--current evaluation and management of the stable patient.
Patients with penetrating cardiac injuries present in a stable or only mildly shocked condition--especially if the laceration has sealed off and the patient has been adequately resuscitated. A large proportion of patients presenting to our unit are in a reasonably stable condition after resuscitation, and rapid diagnosis may be difficult. We present our experience over a 5-year period (191 patients), with particular reference to the stable patient. All patients with penetrating precordial wounds should be assessed for a possible cardiac injury, especially if a period of hypotension has occurred. Clinical signs, central venous pressure, chest radiograph, pericardiocentesis and subxiphoid window are not always helpful in the diagnosis. Cardiac ultrasound is very useful (in the absence of haemothorax), and was performed in 103 of 191 patients, with 8 false-negatives and 3 false-positives. When an unstable patient presents with an obvious diagnosis use of cardiac ultrasound should be restricted. A subxiphoid window has diagnostic value where the cardiac ultrasound is inconclusive.
Surgical management of airway obstruction in primary tuberculosis in children.
BACKGROUND: The role of surgery in the management of airway obstruction from lymphobronchial tuberculosis is discussed in the present article. METHODS: Nine patients were operated on over a 4-year period and are currently presented. The age of the patients ranged between 5 and 28 months and 7 patients were male. Six patients required preoperative ventilation due to respiratory failure and all received standard posterolateral thoracotomies. Partial dissection and enucleation of bulky lymph nodes was performed in all but 1 patient. In that patient, the group of lymph nodes could be removed fully, including the sheath. RESULTS: All patients showed marked improvement and were weaned off the ventilator between 24 and 72 hours postoperatively. Long term follow-up was available in 7 patients and they are all doing well and are free of symptoms. CONCLUSIONS: Enucleation of mediastinal lymph nodes obstructing the airways in young patients with lymphobronchial tuberculosis is safe. It successfully relieves obstruction and is devoid of complication providing that incision, evacuation, and curettage of lymph nodes is performed avoiding overzealous dissection.
Current evaluation of cardiac stab wounds.
BACKGROUND: Patients with penetrating cardiac injuries may be stable or only mildly shocked, especially if the laceration has sealed off and the patient has been aggressively resuscitated. Clinical signs, chest roentgenograms, pericardiocentesis, and subxiphoid window are not always helpful in establishing the diagnosis. We reflect on the current evaluation based on 128 patients. METHODS: There were four groups of patients, ranging from lifeless (group I) to stable (group IV). Patients in groups I and II were prepared immediately for operation. Those in groups III and IV were often investigated further (chest roentgenogram and cardiac ultrasound). RESULTS: Mortality was 8%. Significant findings were a precordial stab, central venous pressure of more than 15 cm of water, one or more clinical signs of tamponade, and initial shock. Cardiac ultrasound was performed in 5 patients in group II (15%), 14 patients in group III (48%), and 37 patients in group IV (86%). There were no false positives, and 6 false negatives (11%). Thirty-one patients (24%) had clotted lacerations. There were no negative sternotomies. CONCLUSIONS: Efficient fluid resuscitation and rapid confirmation of diagnosis with cardiac ultrasound should decrease mortality. Stable patients with a precordial wound should undergo cardiac ultrasound or echocardiogram. Diagnosis may be reliably confirmed in these patients whose clinical signs often fluctuate (or rapidly deteriorate).
Fatty acid composition of selected organs of gerbils maintained on a fat-deficient or fat-supplemented diet.
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Lipid and fatty acid composition of testes of quaking mice.
Testes of quaking mice (sterile mutants) and of controls were analyzed for major lipid classes and fatty acid composition. Of the main lipid classes, only cholesterol esters differed significantly in concentration between the two groups (1.01 for quakers vs 0.69 mg/g wet wt of tissue for controls). The concentration of triglycerides was 4.5-5.0 that of total phosphatides 18-19 and that of free cholesterol 1.9-2.0 mg/g for mutants and controls. The concentrations of phosphatidyl ethanolmanine and of sphingomyelin were both lower in quaking than in normal mice, but only the change in the former was statistically significant. Phosphatidyl choline was the major phosphatide (43-45% of total phosphatides) followed by phosphatidyl ethanolamine (24-26%) and sphingomyelin, phosphatidyl serine, and phosphatidyl inositol (all ca. 7% of total phosphatides). Minor differences between the mutants and controls were observed in concentrations of fatty acids of major lipid classes. The mutants, sterile because of faulty spermatid differentiation, had normal quantities of 22:6 w3 and 22:5 w6. These data are consistent with the hypothesis that the 22-carbon polyenes are associated with the formation of spermatids, rather than with their final differentiation into spermatozoa.
Effect of dietary rapeseed oil on the fatty acid composition of testes of maturing rats.
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Photosynthesis, Transpiration, Leaf Temperature, and Stomatal Activity of Cotton Plants under Varying Water Potentials.
Cotton plants, Gossypium hirsutum L. were grown in a growth room under incident radiation levels of 65, 35, and 17 Langleys per hour to determine the effects of vapor pressure deficits (VPD's) of 2, 9, and 17 mm Hg at high soil water potential, and the effects of decreasing soil water potential and reirrigation on transpiration, leaf temperature, stomatal activity, photosynthesis, and respiration at a VPD of 9 mm Hg.Transpiration was positively correlated with radiation level, air VPD and soil water potential. Reirrigation following stress led to slow recovery, which may be related to root damage occurring during stress. Leaf water potential decreased with, but not as fast as, soil water potential.Leaf temperature was usually positively correlated with light intensity and negatively correlated with transpiration, air VPD, and soil water. At high soil water, leaf temperatures ranged from a fraction of 1 to a few degrees above ambient, except at medium and low light and a VPD of 19 mm Hg when they were slightly below ambient, probably because of increased transpirational cooling. During low soil water leaf temperatures as high as 3.4 degrees above ambient were recorded. Reirrigation reduced leaf temperature before appreciably increasing transpiration. The upper leaf surface tended to be warmer than the lower at the beginning of the day and when soil water was adequate; otherwise there was little difference or the lower surface was warmer. This pattern seemed to reflect transpiration cooling and leaf position effects.Although stomata were more numerous in the lower than the upper epidermis, most of the time a greater percentage of the upper were open. With sufficient soil water present, stomata opened with light and closed with darkness. Fewer stomata opened under low than high light intensity and under even moderate, as compared with high soil water. It required several days following reirrigation for stomata to regain original activity levels.Apparent photosynthesis of cotton leaves occasionally oscillated with variable amplitude and frequency. When soil water was adequate, photosynthesis was nearly proportional to light intensity, with some indication of higher rates at higher VPD's. As soil water decreased, photosynthesis first increased and then markedly decreased. Following reirrigation, photosynthesis rapidly recovered.Respiration was slowed moderately by decreasing soil water but increased before watering. Respiration slowed with increasing leaf age only on leaves that were previously under high light intensity.
SPECTROSCOPIC STABILITY OF CHLOROPHYLLS a AND b AND CERTAIN ANALYTICAL CONSIDERATIONS.
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The faces of group practice. The transformation and progression of physician organizations.
The future will bring an increase in the economic forces which drive the succession of organizational forms. Migrating to integrated models of medical practice will become a survival technique for more and more physicians. This is a frightening prospect for individuals trained to be independent and self reliant. Fortunately, there are a variety of organizational models through which physicians can progress to ease the transition from solo to larger integrated practice forms. Regardless of the evolutionary course, successful physician organizations of the future will be primary care-based, geographically distributed, meaningfully partnered with hospital entities, equipped to accept risk, and lead by strong, business-savvy physician leaders and administrators. This organization will have the ability to flourish within a radically changing climate and will result in the delivery of measurably superior health care to its community.