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Biomedical subjects

F White

Publications and source records attributed to F White.

At least 19 recordsLinked to original sources
PubMed1990

von Willebrand factor is present in the vascular endothelium from normal dogs and from Doberman pinscher dogs with a plasma von Willebrand factor deficiency.

An immunohistochemical study was undertaken to determine the presence and distribution of von Willebrand factor antigen (vWf:Ag) in blood vessels from normal dogs and from Doberman pinscher dogs with a marked plasma deficiency of vWf. vWf:Ag could not be detected in plasma from the Doberman pinscher dogs by ristocetin- and botrocetin-induced platelet agglutination or by EIA. An ELISA assay revealed vWf:Ag levels that were between 2-4% of that in normal canine plasma. Factor VIII:C activity was 30-46% of normal. The activated partial thromboplastin time (APTT) was increased but not the one-stage prothrombin time (OSPT). Four different antibody preparations were used in this study to detect vWf--a monoclonal and a polyclonal antibody prepared against human vWf and 2 polyclonal antibodies against canine vWf. vWf:Ag was detected with monospecific antibody in endothelial cells in veins, venules, and arterioles from normal dogs and vWf-deficient dogs. The histofluorescence observed in vessels of vWf-deficient dogs was indistinguishable from that observed in vessels from normal dogs.

Animals↗
PubMed1990

Simultaneous measurement of neutrophil, lymphocyte, and monocyte glutathione by flow cytometry.

A flow cytometric method for quantitation of glutathione (GSH) was applied to simultaneous analysis of the major leukocyte types in peripheral blood. Cellular thiols (predominantly GSH) were stained with monochlorobimane (MCIB), and thiol fluorescence was measured with a flow cytometer. The fluorescence of the thiols closely reflected the GSH content, as measured by a specific glutathione reductase assay. Fluorescence of individual cell types could be measured after delineating those cells by their light-scatter characteristics, utilizing dual-angle light scatter for discrimination. By this means, GSH contents of 12.5 +/- 2.0 nmol/10(7) neutrophils, 14.5 +/- 2.7 nmol/10(7) monocytes, and 5.0 +/- 1.0 nmol/10(7) lymphocytes were found. The results obtained for neutrophils with the flow cytometer were virtually identical with those obtained with chemical assay in purified samples of neutrophils, indicating the validity of the flow cytometric method.

Cell Separation↗
PubMed1990

Expression and fine structure of the gene encoding N epsilon-(indole-3-acetyl)-L-lysine synthetase from Pseudomonas savastanoi.

The gene encoding N epsilon-(indole-3-acetyl)-L-lysine synthetase, iaaL, from Pseudomonas savastanoi was localized within a 4.25-kilobase EcoRI fragment derived from pIAA1 of oleander strain EW 2009. Two open reading frames of 606 and 1188 nucleotides were identified upon sequencing, which directed the in vitro synthesis of Mr 21,000 and Mr 44,000 proteins. Expression of an open reading frame-2 subclone, pMON686, in Escherichia coli indicates that (indole-3-acetyl)-L-lysine synthetase is encoded solely by open reading frame-2. Hydrophobicity plots of the deduced open reading frame-1 protein suggest that it may be a membrane-bound protein, whereas the predicted iaaL gene product possesses considerable hydrophilic character, consistent with the demonstration of (indole-3-acetyl)-L-lysine synthetase activity in cell-free aqueous extracts. No nucleotide or protein homologies were found between iaaL and any sequences contained within the GenBank or National Biomedical Research Foundation data bases (April 13, 1989).

Amino Acid Sequence↗
PubMed1989

Epidemiology in health promotion: a Canadian perspective.

During the second half of this century, Canada has made major organizational advances in providing universal hospital and medical care programs. Although these advances have largely overshadowed public health issues, the focus is now shifting back to public health with an emphasis on health promotion as a guiding philosophy. Epidemiology has played a key role in these developments. However, as we seek to address matters such as "enhancing people's capacity to cope," "healthy public policy," and "self-care," we find ourselves with a limited data base. So it is now necessary for epidemiology to integrate concepts that have their origins in the social and behavioral sciences, and also to deal with new measures of functional and self-assessed health status. A scientific approach to all this is essential, especially in developing and evaluating health promotion initiatives. In addition, national health goals and objectives are needed to help allocate resources rationally and hold health promotion activities accountable for their own performance.

Canada↗
PubMed1987

Monoclonal antibodies for specific cell labeling: considerations, preparations and preliminary evaluation.

Two types of monoclonal antibodies (MAb), B79.7 and B59.2 determined to be specific for human platelet glycoprotein III.a and III.a.II.b respectively, were labeled with 125I and 111In via diethylenetriaminepentaacetic acid (DTPA) bifunctional chelation technique and evaluated as agents for labeling platelets. Under the chemical conditions chosen one DTPA molecule was bound to one MAb molecule. The specific activities of 111In and 125I preparation averaged 5 and 2.5 Ci/mumol respectively. Both agents showed saturable binding to human platelets. Scatchard analysis showed that the Kd values for 111In-B79.7 and 125I-B79.7 were 83.3 X 10(-9) M and 113.3 X 10(-9) M respectively. The corresponding protein molecules bound per human platelet were 16.75 X 10(3) and 29.5 X 10(3). The Mab B59.2 also reacted with canine platelets and at 50% antigen saturation 49.5% of the added 111In-DTPA-B59.2 was bound to platelets. Using these platelets experimental thrombi were imaged. At 2 h post injection, the thrombi to blood ratios were 15.8. These radiolabeled MAbs are worthy of further evaluation.

Animals↗
PubMed1985

Coronary blood flow and myocardial segment dimensions during simulated dives in seals.

Three harbor seals Phoca vitulina richardsi and five spotted seals Phoca vitulina largha were used in studies of acute episodes of local myocardial ischemia in open-chest, anesthetized animals and of coronary blood flow and regional function as indicated by left ventricular segment dimensions during experimentally simulated dives of conscious, instrumented animals. We observed that seal myocardium, in which there are few coronary anastomoses, responded to brief local occlusion with prompt local dysfunction and systolic bulging; coronary flow in the nondiving seal oscillated irregularly and declined with spontaneous apnea and related falling heart rate; flow continued to oscillate but was much reduced during dives, frequently ceasing entirely for periods as long as 45 s; ventricular segment dimension shortening was reduced intermittently during dives; and elevated heart rate induced during dives by cardiac pacing or by administration of atropine diminished or eliminated the reductions in coronary blood flow. Responses of seal heart reflect the reduction in cardiac metabolic demand during diving and the seal's myocardial adaptation for enhanced anaerobic glycolysis. The seal heart can maintain mechanical function during dives with minimal coronary perfusion, despite the progressive and ultimately profound hypoxia, hypercapnia, and acidosis. Reduced cardiac metabolism, copious glycolytic reserves, and metabolite washout by intermittent brief bursts of coronary blood flow are apparently sufficient to support continued cardiac function, even though the seal heart has little tolerance for acute localized ischemia.

Animals↗
PubMed1984

Detection of ischemic wall dysfunction: comparison between M-mode echocardiography and sonomicrometry.

The quantification of regional ventricular function by M-mode echocardiography was compared to that by sonomicrometry in 10 closed-chest, sedated swine during temporary occlusions of the left circumflex coronary artery. Wall thickening during systole (%WT) was calculated to quantitate regional myocardial function, and percentage of fractional shortening (%FS) was calculated from both sonomicrometer tracings and M-mode echocardiograms. Ventricular dimensions at end diastole and end systole were also compared before and after 2 minutes of coronary artery occlusion. Both techniques detected significant changes in wall thickness, %WT, and %FS after occlusion. Changes in %WT during coronary artery occlusion detected by M-mode echocardiography and sonomicrometry had a significant linear relationship (p less than 0.05). Discrepancy between the two techniques in the measurement of wall thickness at end diastole was attributed to the difficulty in measuring relatively small distances with M-mode echocardiograms. However, we conclude that the clinical M-mode echocardiogram is capable of detecting acute regional wall dysfunction associated with ischemia.

Animals↗
PubMed1983

Ultrastructural morphometry of the myocardium of Thunnus alalunga.

The common ventricle in the heart of the Thunnus alalunga was studied. The ventricular myocardium consists of an outer compact layer and a thick inner spongy layer. The compact layer has slightly larger cells (4-6 microns diameter) than the spongy layer (2.5-5 microns diameter). Ultrastructurally the myocardium displays normal arrangements of myofibrils and mitochondria. The sarcoplasmic reticulum is poorly developed. The intercalated discs are simple with the fascia adherens being the most frequent junctional type observed; occasionally a desmosome was seen. Nexus type junctions are present but are unassociated with the intercalated discs. There are no t-tubules evident but the plasmalemma exhibits numerous caveolae which rarely form couplings with the sarcoplasmic reticulum. A morphometric analysis of the volume percent of mitochondria and myofibrils showed that the myocardial cells in the spongy layer of the heart have a significantly greater volume percentage of mitochondria than the compact layer. No significant differences were found between myocardial regions when the volume percentages of myofibrils were compared. The physiological studies revealed that the albacore tuna has heart rates (120 bpm) and ventricular blood pressures (100 mmHg) that are among the highest reported for fish.

Animals↗
PubMed1983

Sustained regional dysfunction produced by prolonged coronary stenosis: gradual recovery after reperfusion.

Prolonged nontransmural ischemia was produced and the early and late effects of reperfusion were studied in 10 conscious dogs instrumented over the long term. Five hours of partial circumflex coronary artery stenosis was produced with a hydraulic occluder, followed by gradual release over 20 min, with measurements of left ventricular pressure, regional myocardial function (systolic wall thickening by sonomicrometry), coronary blood flow velocity (pulsed Doppler), and myocardial blood flow (microspheres). During coronary stenosis the occluder was adjusted frequently to maintain a reduction of systolic wall thickening to 50% to 75% of control (average 62.6% of control). Myocardial blood flow in the ischemic area at 4 hr of partial coronary stenosis was reduced in the inner layers of the myocardium (subendocardium, from 0.81 +/- 0.18 at control to 0.36 +/- 0.08 SD, p less than .01; midwall, from 0.77 +/- 0.20 to 0.46 +/- 0.07 ml/min/g, p less than .01), accompanied by significant ST segment elevation on the subendocardial electrogram (0.83 +/- 0.96 to 4.58 +/- 4.10 mV; p less than .05) and decreased left ventricular dP/dt (3503 +/- 462 to 2991 +/- 339 mm Hg/sec; p less than .01). Within a few minutes after complete release of partial coronary stenosis, ST segments returned to control and myocardial blood flow of the inner layers was increased (subendocardium, 1.37 +/- 0.39, p less than .01; midwall, 0.97 +/- 0.28, p less than .05), but systolic wall thickening and left ventricular dP/dt were significantly depressed and remained reduced at 24, 48, and 72 hr when myocardial blood flow was normal. By seven days, systolic wall thickening and left ventricular dP/dt had returned to control (94.1 +/- 7.0% of control, 3353 +/- 605 mm Hg/sec, respectively; NS). Histologic changes caused by ischemia constituted only 2.7% (average) of the tissue between the crystals in the ischemic wall, but ischemic damage in the posterior papillary muscle, which did not contain crystals, was 31.9%. Thus, regional myocardial dysfunction reduced by nontransmural ischemia for 5 hr persisted for at least 3 days, with only slight damage to the left ventricular free wall but considerable infarction of the posterior papillary muscle. Full recovery of regional and global contractile function of the free wall then occurred within a period of 1 week.

Animals↗
PubMed1983

Daily variation in food intake of infants from 2 to 18 months.

This paper examines the day to day variation in energy intake of 48 breast-fed infants studied by 4-day diet records at monthly intervals from 6 weeks to 7 1/2 months and of 37 fully weaned infants studied at 10, 12, 15 and 18 months. Variation was low in the fully breast-fed infants, increased as solids were introduced, and at 18 months, approached values found for adults. Pooled within-subject coefficient of variation (CVw) at 1-3, 3-5, 5-7, 10 + 12, and 15 + 18 months was 10.6, 10.6, 12.0, 13.6, 18.1 per cent. Between-subject coefficient of variation (CVb) was 20.1, 19.3, 16.9, 19.4 and 23.3 per cent at these ages. Some individuals were more variable than others; the range of CVw at each age was wide; at 2-4 and 15-18 months it was 1-21 and 6-30 per cent respectively. The number of daily records needed to assess energy intake of groups of individuals with a specified degree of confidence is discussed together with implications for the planning of dietary surveys.

Age Factors↗