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Biomedical subjects

B Perry

Publications and source records attributed to B Perry.

At least 37 records · Page 2Linked to original sources
PubMed1996

Myocardial contrast echocardiography: reliable, safe, and efficacious myocardial perfusion assessment after intravenous injections of a new echocardiographic contrast agent.

Reliable and reproducible myocardial opacification after intravenous administration of echocardiographic contrast agents has remained elusive. This study was performed to determine whether a new agent, FS069, a suspension of perfluoropropane-filled albumin microspheres (3.6 microns average microbubble size, concentration 8 x 8(8)/ml), could achieve safe and successful myocardial opacification in open-chest dogs. Seventeen dogs (group 1, n = 7, group 2, n = 10) underwent two-dimensional echocardiography before, during, and after the administration of intravenous FS069. Safety was evaluated by measuring arterial and pulmonary artery pressures, heart rate, blood gases, systolic function, myocardial blood flow, and postmortem analysis of myocardial viability by triphenyl-tetrazolium chloride staining. Efficacy to detect changes in regional myocardial perfusion was assessed by injecting FS069 at baseline, after sequential coronary occlusions and reperfusion, and during intravenous vasodilators with and without coronary occlusions. Results were compared with radiolabeled microspheres. FS069 was found to be safe and effective. In the absence of coronary occlusions, uniform myocardial opacification was observed in all dogs. A perfusion defect was observed in all dogs during coronary occlusions. Background-subtracted peak contrast intensity in the myocardium correctly identified regional myocardial blood flow changes and showed a significant correlation with radiolabeled microspheres (r = 0.65, p = 0.0001).

Albumins↗
PubMed1996

Potential clinical implications of abnormal myocardial perfusion patterns immediately after reperfusion in a canine model: a myocardial contrast echocardiography study.

During myocardial infarction, lack of myocardial opacification after reperfusion has been associated with poor or no recovery of function. We have previously documented the presence of perfusion abnormalities after brief coronary occlusions without infarction and the absence of perfusion abnormalities after prolonged occlusions with infarction. To characterize myocardial perfusion patterns immediately after reperfusion, we studied 53 animals in two groups in a coronary occlusion-reperfusion model. Temporary occlusions (group 1, 15 minutes; group 2, 30 to 360 minutes) were performed, followed by reperfusion with and without dobutamine. Myocardial contrast echocardiography was performed with aortic root injections of sonicated 5% serum human albumin (Albunex) during each intervention. Group 1 dogs showed no evidence of myocardial infarction. In group 2, 26 of 40 dogs had infarctions. After reperfusion, no perfusion abnormalities were seen in 13 of 26 group 2 dogs with infarctions; perfusion abnormalities were identified after reperfusion in 2 of 13 group 1 and in 8 of 14 group 2 dogs without infarctions. In animals subjected to prolonged ischemia, the absence of perfusion abnormalities after reperfusion did not rule out the presence of necrosis. Similarly, in animals without infarction subjected to ischemia, the presence of a perfusion defect after reperfusion did not represent the presence of necrosis but an abnormal microvascular reserve. These results suggest that early after reperfusion, assessment of perfusion by myocardial contrast echocardiography has significant limitations in the evaluation of myocardial viability and salvage.

Animals↗
PubMed1996

Second annual Helene Hudson Memorial Lecture. I am a nurse.

The focus of this study was an exploration of the nature of exceptionally competent oncology nursing practice. Through a combination of data gathering approaches--conversation, observation and narrative exchange--the beliefs, actions and effects of the actions of eight exemplary nurse informants were studied. Analysis revealed three themes related to the action of the exemplary nurses: Dialogue in silence, mutual touch and sharing the lighter side of life. Additional analysis led to a category called effects of nursing actions. Again, three themes were highlighted as effects: Affirmation of the nurse and patient, connecting and joint transcendence.

Health Knowledge, Attitudes, Practice↗
PubMed1996

Searching for the Magic Johnson effect: AIDS, adolescents, and celebrity disclosure.

The objectives of this study were to measure changes in AIDS-related attitudes and behaviors in adolescents in the 13 months following Magic Johnson's disclosure that he was HIV positive, and to test whether gender, race, age, sexual experience, and pre-existing HIV-avoidant behaviors would emerge as significant dependent variables. Adolescent clinic attendees (N = 181) ages 12-19 in four cities completed a questionnaire assessing change in AIDS-related attitudes and behaviors since Johnson's announcement. Respondents were divided into low-risk and at-risk groups. Sixty percent of respondents reported that Magic Johnson's announcement had increased their awareness of AIDS, 65.4% reported increased self-efficacy in a sexual situation, 37.2% reported that they had changed their perceived AIDS risk, 37.8% described increased resistance to peer pressure for sexual intercourse. The low-risk group was more likely to report increased self-efficacy and resistance to peer pressure but no change in perceived risk or increased AIDS awareness. Significant relationships were found between gender and increased AIDS awareness, gender and increased resistance to peer pressure to engage in sexual intercourse, race and increased AIDS awareness, and more lifetime sex partners and increased self-efficacy.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Increased activity of porcine pancreatic phospholipase A2 by designed long-range electrostatic stabilisation of the transition state.

Stabilisation of the catalytic transition state by long-range charge interactions has been tested with mutagenesis for porcine pancreatic phospholipase A2. Electrostatics calculations were used to determine locations which would interact preferentially with one part of the dipolar charge separation that is believed to develop in the transition state. Experiment shows increased enzyme activity relative to wild-type recombinant enzyme for mutants N97D and N101D, consistent with the design.

Animals↗
PubMed1995

Regional renal blood flow measurements using radioactive microspheres in a chronic porcine model with unilateral vesicoureteral reflux.

95Niobium labeled radioactive microspheres were used to determine regional renal blood flows in a porcine model of chronic sterile vesicoureteral reflux. Unilateral vesicoureteral reflux was surgically created in 5 mini-pigs and regional renal blood flows were determined by microsphere injection 6 months later. The contralateral nonrefluxing kidney acted as a control. There was a significant reduction of flow in the inner cortical regions of the middle (78% of control, p < or = 0.0437) and lower poles (69% of control, p < or = 0.0274), and the juxta-medullary cortical region of the lower pole (67% of control, p < or = 0.0124). There was no difference in flow in the other regions or when comparing whole kidneys. There were no differences between refluxing and nonrefluxing kidneys when comparing ratios of inner to outer cortical flow level by level. These observations are in contrast to those in acutely created vesicoureteral reflux in a porcine model, which had no significant differences in flow in any region using the microsphere technique. Decreases of blood flow in certain cortical regions may help explain some of the physiological changes in vesicoureteral reflux in children and experimental models of reflux.

Animals↗
PubMed1994

Making a small enzyme smaller; removing the conserved loop structure of hen lysozyme.

Engineering a smaller lysozyme is a challenge for both random and site-directed mutagenesis. This paper illustrates the power of knowledge-based protein engineering in the design of a smaller lysozyme that folds correctly and has activity against bacterial cell walls. In this smaller lysozyme the conserved disulphide bridged loop is replaced by a short loop. The long loop was selected because it buries a predominantly hydrophilic surface. The short loop was discovered by searching for appropriate fragments in the protein databank. This approach is important in the design of small enzymes useful to the food industry.

Animals↗
PubMed1993

Physiological consequence of expression of soluble and active hen egg white lysozyme in Escherichia coli.

Hen egg white lysozyme was expressed as a protein fusion with the OmpA signal sequence and an octapeptide linker in Escherichia coli. The expression yielded soluble and enzymatically active lysozyme. Lysozyme activity was detected in the periplasmic space, in the cytosol and in the insoluble cytosolic fraction of E. coli. The results indicate that the environmental conditions in both the cytosol and the periplasmic space of E. coli were sufficient for correct protein folding and disulphide bond formation of eukaryotic recombinant lysozyme. However, the expression of active enzyme in E. coli consequently led to bacterial cell lysis due to hydrolysis of the peptidoglucan.

Animals↗
PubMed1991

Modification of the stability of phospholipase A2 by charge engineering.

Electrostatic interactions play an important role in stabilizing the folded conformation of globular proteins. Here we predict the change in stability of charge engineered mutants, construct these mutants and compare the predicted change in stability with that observed. The change in stability was correctly predicted for two of the three mutants and the factors responsible for the discrepancy between observation and prediction for the third mutant are discussed.

Enzyme Stability↗
PubMed1991

Production and characterisation of monoclonal antibodies to parathyroid hormone (1-34).

Monoclonal antibodies to the biologically active N terminal region of parathyroid hormone (PTH) suitable for use in the measurement of circulating PTH concentrations have proved difficult to produce. In this study, no serum PTH antibody titres could be detected in mice using synthetic human PTH (1-34) (free or coupled to albumin) or PTH (1-10) (coupled to keyhole limpet haemocyanin) as immunogen. A consistent response to PTH (1-34) peptide was obtained in DA rats. We have produced five monoclonal antibodies to PTH (1-34) derived from the fusion of DA rat spleen cells and the mouse myeloma line X63 Ag.8.653. Bulk production of the antibodies was achieved using congenitally athymic mice for ascites production. Antibody assessment studies revealed the antibodies to be sensitive to the oxidation state of the methionine residues in PTH (1-34). Two of the antibodies, 3B3 and 6E3, were shown to be of potential use in measuring circulating PTH (1-84) when used in combination with available antibodies to C terminal PTH. A third antibody, 4G3, which failed to recognise PTH (1-84) when used in combination with 3B3, formed the basis of a specific assay for PTH (1-34).

Animals↗
PubMed1991

Renal blood flow measurements using radioactive microspheres in a porcine model with unilateral vesicoureteral reflux.

Renal blood flow was studied in Yorkshire pigs with surgically created unilateral vesicoureteral reflux using radionuclide labeled microspheres. The contralateral, nonrefluxing kidney served as a within-subject control and a group of nonoperated pigs without reflux served as an additional control group. Unilateral reflux did not change the distribution of whole renal blood flow between the refluxing and nonrefluxing kidneys. In addition, reflux had only minor effects upon the distribution of blood flow to cortical regions within the kidneys.

Animals↗
PubMed1991

Specificity of two-site immunometric assays.

The assessment of specificity in two-site immunometric assays is complex. Conventional approaches based on standard substitution with cross-reactant may yield misleading results. An 'in-house' immunoradiometric assay (IRMA) for human growth hormone (hGH) appeared free from cross-reactivity with human placental lactogen (hPL) in a single point standard substitution experiment performed by the United Kingdom External Quality Assessment Scheme (UK EQAS). However, detailed studies based on the substitution of hGH standards with hPL cross-reactant, the addition of hPL cross-reactant to hGH standards and the recovery of added hGH from endogenous cross-reactant (sera from pregnant subjects) revealed gross cross-reactivity of hPL in the hGH assay. We recommend that the validation of assay specificity should require the demonstration of quantitative recovery of a range of analyte concentrations from human sera that contain varying endogenous concentrations of cross-reactant.

Calibration↗
PubMed1991

A two-site immunoradiometric assay for PTH(1-84) using N and C terminal specific monoclonal antibodies.

We report the development of a two-site immunoradiometric assay for PTH(1-84) based on two site-specific monoclonal antibodies--3B3 (radiolabelled antibody) specific for PTH(1-34) and ESQ1 (on solid phase) specific for PTH(74-84). Antibody 3B3 is sensitive to the oxidation of the methionine residues in PTH(1-34) therefore hydrogen peroxide (0.1 M) is added to the incubation mixture. Validation studies confirm quantitative recovery of both oxidized and reduced PTH(1-84). The assay has a minimum detection limit of 0.5 pmol/L and a range of 1.5-250 pmol/L with an intra-assay CV of less than 10% (2.8-250 pmol/L less than 5% CV). Studies on clinical samples indicate good discrimination between normal subjects (mean 2.21; range 1.0-5.0 pmol/L) and patients with primary hyperparathyroidism (mean 21.0; range 5.8-100 pmol/L) who in turn are well separated from patients with hypercalcaemia of malignancy (14/18 less than 0.5 pmol/L).

Adult↗
PubMed1991

Ovulation, fertilization and early embryonic development in the bitch (Canis familiaris).

Using circulating plasma hormone estimations, ovulation was monitored in bitches. The results obtained indicate that the timing of ovulation bears little relationship to alterations in sexual behaviour. The bitches were killed and reproductive tracts were removed at various intervals after ovulation and ova or embryos were recovered. The embryo stages were assessed visually and some were investigated histologically. Embryonic development, to early blastocyst stage, took place within the oviducts during the first 12 days after ovulation and there was a marked increase in size between the early and late blastocyst. A culture system using cells from the uterine tube supported the development of one 1-cell embryo to the morula stage.

Animals↗