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Biomedical subjects

B Harrison

Publications and source records attributed to B Harrison.

At least 91 records · Page 5Linked to original sources
PubMed1990

Preliminary studies of mineralization during distraction osteogenesis.

Distraction osteogenesis by the Ilizarov method was performed on 20 dogs. Mineralization at the site of the left tibial metaphyseal lengthening was measured by weekly quantitative computer tomography (QCT) using the contralateral tibia as a control. Four dogs each were killed on Days 7, 14, 21, and 28 of distraction in order to correlate QCT with microradiology, nondecalcified histology, quantitative calcium analysis, and scanning electron microscopy. It was consistently found that intramembranous ossification proceeded centripetally from each corticotomy surface toward the central fibrous interzone. Bone columns crystallized along longitudinally oriented collagen bundles, expanding circumferentially to surrounding bundles. As the distraction gap increased, the bone columns increased in length and in diameter, while the fibrous interzone remained about 4 mm long. Histologically, the bone columns resembled stalagmites and stalactites, as seen by microradiography and scanning electron microscopy, that projected from each corticotomy surface toward the center. These cones reached maximum diameters of 150-200 mu at the corticotomy surfaces. Radiodensity (QCT) increased gradually from the central fibrous interzone toward each corticotomy surface. Mineral density, as determined by calcium quantification, reflected the microscopic geometry and radiographic polarity.

Animals↗
PubMed1989

Properties of lymph-borne (veiled) dendritic cells in culture. II. Expression of the IL-2 receptor: role of GM-CSF.

Fresh lymph-borne (veiled) dendritic cells (L-DC) in the rat are almost totally negative for the interleukin-2 (IL-2) receptor detected by the monoclonal antibody (mAb) MRC OX39. After 16 hr culture more than 90% of L-DC are OX39 positive, and increased levels of expression can be seen within 5 hr culture. In cultures of L-DC and allogeneic lymphocytes. L-DC appear to express the IL-2 receptor more rapidly than lymphocytes. The intensity of labelling of L-DC is variable but maximal levels are similar to those seen on lymphoblasts. Culture in the presence of concanavalin A (Con A)-stimulated spleen cell supernatants or recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) results in a more rapid and intense expression of the IL-2 receptor by L-DC. L-DC cultured following rigorous T-cell depletion, or derived from athymic rats also express the IL-2 receptor after culture with GM-CSF. Cultured, but not fresh, L-DC bind iodinated recombinant IL-2 in a dose-dependent manner and binding is inhibited by excess unlabelled ligand. The amount of IL-2 bound varies but maximal amounts are similar to those bound by lymphoblasts. Following intravenous endotoxin injection, a large proportion of freshly collected L-DC express the IL-2 receptor and the number of L-DC released into the lymph is increased. An antibody to the IL-2 receptor which blocks an allogeneic MLR has no effect on a xenogeneic MLR using rat L-DC as stimulators and mouse lymphocytes as responders.

Animals↗
PubMed1989

Preservation of myocardial ultrastructure after 24 hours of Klebsiella sepsis: histologic, functional, and biochemical correlations.

Myocardial function with ultrastructure and high energy phosphate levels in dogs was correlated after 24 hours of sepsis using live Klebsiella aerogenes. All animals developed progressive hemodynamic deterioration over a 24 hour period. Mean arterial pressure decreased from 148 +/- 7 mmHg to 85 (P less than 0.01) and cardiac output decreased from 3.43 +/- .31 to 1.6 +/- 0.5 L/min. Left ventricular stroke work decreased from 48.2 +/- 5 to 18.1 +/- 6 gm-meters (P less than 0.001). Systemic and pulmonary vascular resistances were increased at 24 hours (3,538 +/- 27 to 7,404 +/- 1,400 dyne/sec/cm-5 (P less than 0.01), and 185 +/- 20 and 619 +/- 90 dyne/sec/cm-5 (P less than 0.001), respectively. Left ventricular function curves at 24 hours showed a fixed low output. However, myocardial ultrastructure was preserved and high energy phosphate levels remained normal. These observations correlate well with the changes seen clinically in early gram negative sepsis in hypovolemic patients. Thus, this appears to be a suitable model for further investigation of the effects of gram negative sepsis on myocardial performance, ultrastructure, and maintenance of energy stores.

Animals↗
PubMed1988

Importance of nurse caring behaviors as perceived by patients after myocardial infarction.

Our purpose was to identify nursing behaviors perceived as indicators of caring by patients who have had a myocardial infarction. A sample of 22 hospitalized patients were interviewed, with use of an open-ended question and the Caring Behaviors Assessment, to determine what things nurses said or did that conveyed caring to the patients during their stay in the coronary care unit (CCU). An analysis of the relative importance of each identified behavior revealed that nursing actions that focused on the physical care and monitoring of patients were seen as most indicative of caring. Teaching activities were also perceived as significant whereas extra, individualized aspects of care were viewed as less important in the critical care setting. No significant differences in perceptions were found on the basis of sex, age, education level, number of CCU admissions, or length of CCU stay. Critical care nurses should be aware that assessment activities and demonstration of professional competence are viewed by patients as significant expressions of caring.

Adult↗
PubMed1987

Macromolecular crowding increases binding of DNA polymerase to DNA: an adaptive effect.

Macromolecular crowding extends the range of ionic conditions supporting high DNA polymerase reaction rates. Reactions tested were nick-translation and gap-filling by DNA polymerase I of Escherichia coli, nuclease and polymerase activities of the large fragment of that polymerase, and polymerization by the T4 DNA polymerase. For all of these reactions, high concentrations of nonspecific polymers increased enzymatic activity under otherwise inhibitory conditions resulting from relatively high ionic strength. The primary mechanism of the polymer effect seems to be to increase the binding of polymerase to DNA. We suggest that this effect on protein-DNA complexes is only one example of a general "metabolic buffering" action of crowded solutions on a variety of macromolecular interactions.

Binding Sites↗
PubMed1986

T4 polynucleotide kinase: macromolecular crowding increases the efficiency of reaction at DNA termini.

The amount of reaction catalyzed by T4 polynucleotide kinase on a variety of its substrates is greatly increased in the presence of polyethylene glycol 8000 (PEG 8000). Both the forward and reverse reactions as well as the exchange reaction can be stimulated. The stimulation is a general effect on T4 polynucleotide kinase reactions involving high molecular weight DNA substrates. The use of PEG 8000 is particularly advantageous for labeling or removing terminal 5'-phosphate groups which are only slowly or incompletely labeled or removed under ordinary conditions, such as those at recessed termini or at "nicks" in duplex DNA, although the reaction on blunt-ended or protruding termini is also increased. It is further advantageous for labeling very low concentrations of substrates.

Adenosine Diphosphate↗
PubMed1986

Stabilization of T4 polynucleotide kinase by macromolecular crowding.

T4 polynucleotide kinase rapidly loses activity during its reaction on duplex DNA termini. Addition of high concentrations of nonspecific polymers reverses or prevents this inactivation. In contrast, additions of related materials of lower molecular weight are relatively ineffective in stabilizing the kinase. Such a pattern suggests that the stabilizing effects of polymers on kinase activity are due to macromolecular crowding. An effect of crowding on the known tendency of the kinase to undergo oligomerization reactions is consistent with our observations.

DNA↗
PubMed1986

Psychological services offered to female veterans.

Questionnaires were sent to 153 chiefs of Veterans Administration psychology services to request information on service provision to women veterans; 91 responses were received. Services were classified according to four categories: (a) individual women served in response to requests; (b) individual programs designed to meet specific needs; (c) educational programs offered to female clients; and (d) staff training programs. Correlations between each of the four categories and the following factors were calculated: (a) size of the city as determined by population in which each Veterans Administration Medical Center is located; (b) state population of female veterans; (c) number of female staff psychologists; (d) annual percentage of female clients served; (e) income of female clients; (f) total number of psychologists on the staff; and (g) total annual number of clients. Significant correlations were found between number of services offered routinely in response to requests and each of the following factors: (a) state population of female veterans; (b) income of female veteran clients; (c) total number of psychologists on the staff; and (d) annual number of clients.

Female↗
PubMed1986

The search for volumetric symmetry in reconstruction of the breast after mastectomy.

The difficulty in achieving volumetric symmetry in the course of reconstruction of the breast after mastectomy is emphasised. The published methods of estimating breast volume are outlined before describing a new apparatus relying on the displacement of air within a large calibrated cylinder and which, by objective and clinical evaluation, has proved to be gratifyingly accurate. The method of achieving symmetry is illustrated in a patient originally referred with an inadequate breast mound reconstruction.

Breast↗