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Biomedical subjects

B S Edwards

Publications and source records attributed to B S Edwards.

At least 73 records · Page 4Linked to original sources
PubMed1990

Cardiac transplantation in patients with preexisting neoplastic diseases.

Cardiac transplantation has traditionally been reserved for individuals with end-stage congestive heart failure (CHF) in whom there is no history of other life-threatening systemic disorders. In most transplant centers, patients with a history of malignancy and severe heart failure have not been considered acceptable candidates for cardiac transplantation. In the last 4 years at Stanford University Medical Center, 8 cardiac transplants have been performed in 7 patients with a history of neoplastic disease. Six of these patients had already received treatment for lymphoproliferative disorders and in 1 case, a patient underwent a transplant after treatment for adenocarcinoma of the colon. Six of the 7 patients were discharged from the hospital and in that group, the 1-year posttransplant survival rate was 71%. This was comparable to an overall 1-year survival rate of 80% for patients undergoing a cardiac transplant at our center during the same period of time. At follow-up averaging over 2 years, there has been 1 case of recurrent neoplasia. One patient with evidence of radiation-induced pulmonary damage died of respiratory failure 2 days after transplantation. One patient required retransplantation because of intractable rejection and subsequently died from infectious complications. Immunosuppressive therapy in these patients has not been associated with an increased risk for neoplastic recurrence or for the development of posttransplant lymphoproliferative disorders. The current study demonstrates that in a carefully selected group, previously treated neoplastic disease should not represent a contraindication to cardiac transplantation.

Adolescent↗
PubMed1990

Expression of atrial natriuretic factor in the human ventricle is independent of chamber dilation.

This study investigated the presence of atrial natriuretic factor in ventricular tissue obtained from humans with dilated or restrictive heart disease. In 17 patients with ventricular dilation and impaired systolic function and in 8 patients with restrictive heart disease and preserved systolic function, the presence of ventricular atrial natriuretic factor was investigated in tissue obtained by ventricular endomyocardial biopsy. The objective of the study was to determine if the ventricular presence of atrial natriuretic factor is dependent on ventricular dilation. Left ventricular end-diastolic volume index was greater in the group with dilated cardiomyopathy than in the group with restrictive cardiomyopathy (134 +/- 13 versus 78 +/- 5 ml/m2, p less than 0.05); end-diastolic pressure was elevated in the two groups (20 +/- 2 versus 25 +/- 4 mm Hg, p = NS). With the use of immunohistochemical techniques, ventricular atrial natriuretic factor was clearly detected in 15 of the 17 patients with dilated cardiomyopathy and in 6 of the 8 patients with restrictive cardiomyopathy. This study demonstrates the high prevalence of ventricular atrial natriuretic factor in living patients with either systolic or diastolic dysfunction. Whereas in the atria, stretch or dilation may be an important stimulus, atrial natriuretic factor in the ventricular chamber occurs independent of dilation.

Atrial Natriuretic Factor↗
PubMed1990

Renal-endocrine adaptations to endogenous atrial natriuretic factor during tachycardia-induced reductions in renal perfusion pressure.

Atrial pressure, atrial natriuretic factor (ANF), the renin-angiotensin-aldosterone system, and renal hemodynamic functions were examined during and after right ventricular pacing in anesthetized dogs (n = 9). Mean arterial pressure, cardiac output, and renal blood flow decreased during tachycardia while right and left atrial pressures increased. ANF markedly increased during tachycardia but urinary and fractional excretion of sodium were unchanged from control. Plasma renin activity was not increased during pacing despite the decrease in renal perfusion pressure. After tachycardia and restoration of mean arterial pressure to control, ANF declined but remained elevated above control despite a return of atrial pressure to control level. After tachycardia, urinary and fractional sodium excretion increased significantly in the absence of an increase in glomerular filtration rate. These findings support the following conclusions: 1) tachycardia increases ANF in association with increased atrial pressure; however, an elevation of ANF persists following tachycardia despite the absence of the persistent stimulus of elevated atrial pressures; 2) the increase in ANF during tachycardia may contribute to the absence of a decrease in sodium excretion and activation of the renin-angiotensin system that occurs with reduction in renal perfusion pressure; and 3) tachycardia-induced natriuresis may be dependent on an increase in ANF and the maintenance of renal perfusion pressure.

Aldosterone↗
PubMed1990

Does the DNR patient belong in the ICU?

A small but significant percentage of ICU patients are designated DNR at some time during their ICU stay. DNR patients in the ICU are more ill, use more resources (including nursing care) and have a higher mortality rate than non-DNR patients. In an age of a critical care nursing shortage, spiraling health costs, and an emphasis on the just allocation and use of scarce resources, the question whether DNR patients should be excluded from the ICU is appropriately raised. After examination, a model policy to exclude DNR patients from the ICU was rejected because a policy excluding DNR patients from the ICU would have adverse effects on patient autonomy, beneficence, the nurse-patient relationship and fidelity, and the practice of writing DNR orders. Furthermore, such a policy would not resolve triage problems. DNR patients can appropriately be given curative or palliative treatment in an ICU when their treatment goals are reasonable and the treatment can only be given in the ICU. Conversely, DNR patients do not belong in the ICU when their treatment goals are inappropriate or when their treatment could be received on another unit. "Appropriate" and "inappropriate" treatment was not thoroughly examined except to define them in relation to Young's "point Z," the theoretical point on a life-death continuum at which one stops prolonging life and instead prolongs death. In this authors' opinion, beyond point Z, only palliative treatment is justified in the ICU. DNR patients beyond point Z should not receive curative treatments in the ICU. Many DNR patients fitting this description remain in ICUs, however, perhaps because of physician reluctance to withdraw or withhold life-sustaining treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical Care↗
PubMed1989

Relationship between target cell recognition and temporal fluctuations in intracellular Ca2+ of human NK cells.

Temporal changes in intracellular Ca2+ concentration, [Ca2+]i, of resting human peripheral blood NK cells in response to target cell binding were evaluated by flow cytometry. [Ca2+]i was significantly elevated in PBL and purified NK cells bound to NK-sensitive K562 and HSB2 target cells, but not in those bound to NK-resistant MD1 B-lymphoblastoid cells. Thus, a) the ability of a target cell to elicit a Ca2+ flux response correlated with its sensitivity to lysis of NK cells, and b) adhesion alone was not a sufficient stimulus for response induction. Conjugates of NK cells bound to K562 target cells were sorted onto agarose-coated slides on the basis of relative NK cell [Ca2+]i and evaluated in 19-hr single cell agarose cytotoxicity assays. In contrast to those with basal levels of [Ca2+]i, NK cells with elevated [Ca2+]i bound more strongly to target cells, as judged by the stability of conjugates to sort-related shear forces (p less than 0.01), and more frequently killed the target cell to which they were attached (p less than 0.05). Temporal fluctuations in [Ca2+]i were observed in target-bound NK cells in both the presence and absence of extracellular Ca2+. Thus, influx of extracellular Ca2+ and release of Ca2+ from internal stores both appeared to contribute to the NK cell Ca2+ flux response triggered by adhesion to appropriate target cells. These results support the hypothesis that such fluctuations in NK cell [Ca2+]i constitute an early signal flagging the occurrence of NK cell recognition.

Calcium↗
PubMed1989

Lymphocyte subset analysis by flow cytometry. Comparison of three different staining techniques and effects of blood storage.

Flow cytometric analysis enables the researcher and clinician to enumerate lymphocyte subsets in peripheral blood mononuclear cells (PBMC). Often blood samples are collected at one site and then shipped to another site for analysis. Many options in the storage, preparation, and staining of PBMC for flow cytometric analysis exist. Preparation techniques include the conventional Ficoll-Paque (FP) density centrifugation versus the whole blood technique with red blood cells (RBC) lysed using a lysing reagent. In comparing three methods of PBMC preparation, and comparing the staining of fresh blood cells with staining of cells after storage for 24 h at 4 degrees C, analyses show how these different techniques affect the results.

Antigens, Differentiation↗
PubMed1989

Efficient use of monoclonal antibodies for immunofluorescence.

We describe here a simple and rapid small volume microplate-based immunofluorescence staining method in which fluorochrome-conjugated monoclonal antibodies (MAb) from three different manufacturers, used at a single standardized quantity (50 ng per test), resulted in optimal staining of human lymphocyte subsets. Staining reactions were robust, in that the number of lymphocytes used could be varied over a wide range (3 x 10(4)-1 x 10(6) cells per microplate well) without significant effects on the fluorescence intensity of staining or nonspecific binding by MAb. A measure of the efficiency of MAb use was the number of tests theoretically possible to perform with nominal 100 test kits; this figure ranged from 400 to 20,000 tests, depending on the MAb in question. This method was readily adaptable to both single- and two-color immunofluorescence analysis.

Antibodies, Monoclonal↗
PubMed1989

Comprehensive quality assessment approach for flow cytometric immunophenotyping of human lymphocytes.

Flow cytometric immunophenotypic (IPT) evaluation has become an important adjunct to clinical patient management and epidemiological studies. This has precipitated a need for stringent quality assessment (QA) procedures to ascertain data integrity. We evaluated a QA approach to monitor all elements of the immunophenotyping process, inclusive of blood collection and processing procedures as well as of staining reagent and instrument performance. Central to our approach was preparation each day, in parallel with clinical analytes, of lymphocytes from healthy donors, selected from a 15 donor panel. IPT parameters evaluated over a 19 month period included frequencies of CD3+, CD4+, CD8+, and CD20+ lymphocytes and the ratio of CD4+ to CD8+ lymphocytes. The sensitivity for analytical error detection was reflected by median coefficients of variation of these parameters within individual panel donors, which were 4.1%, 4.5%, 3.9%, 8.2%, and 10.1%, respectively. IPT parameter values were determined each day for two of the panel donors, then averaged and standardized to obtain a quality or Q variate, which was the basis of QA. Error detection sensitivity decreased 0.6-1.7% and the number of false rejections increased 1.2-3.3% when one panel donor rather than two was used daily for QA. This study also illuminated important aspects of what constitutes the norm for longitudinal IPT parameter variation in healthy individuals including: 1) a generally low degree of temporal parameter variation within individual donors, but 2) significant differences between donors with respect to variance estimates for CD3+ and CD8+ lymphocyte frequencies and CD4+/CD8+ lymphocyte ratios, and 3) an apparent seasonal pattern of variation in CD4+ T-cell frequencies.

Antibodies, Monoclonal↗
PubMed1989

Isotype, distribution and target analysis of lymphocyte reactive antibodies in patients with human immunodeficiency virus infection.

Anti-lymphocyte (ALA) antibodies were investigated by using both microcytotoxicity and immunofluorescence analyses in 87 subjects with different clinical features of human immunodeficiency virus (HIV) infection. A similar mean percentage of killing in microcytotoxicity assays using heterologous lymphocytes as cellular target was recorded in four groups of patients, including 36 HIV-seropositive asymptomatic subjects, 34 patients with HIV-induced lymphadenopathy syndrome (LAS), 13 with acquired immunodeficiency syndrome (AIDS)-related complex (ARC), and 4 patients with the full-blown AIDS. Conversely, an increasing percentage of ALA-positive subjects paralleled the evolution of the HIV infection. The majority of ALA were IgM isotype with a significant reactivity against T cells. This specificity was indifferently directed to CD3+, CD4+, and CD8+ lymphocytes. In additional experiments employing enzymatic digestion of lymphocyte membrane antigens, we demonstrated that CD4 and CD8 receptors were digested by the pronase, whereas CD3 molecules were highly resistant. Subsequent flow cytometry analyses using these pronase-digested T cells showed that reactivity of ALA for their target was unchanged. Our data suggest that antigenic specificities of ALA in HIV infection are resistant to pronase treatment and are not related to CD4 and CD8 molecules.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Restoration of renal response to atrial natriuretic factor in experimental low-output heart failure.

The renal response to atrial natriuretic factor (ANF) has been shown to be blunted in several experimental models of acute and chronic congestive heart failure. The mechanism responsible for this blunted response has been postulated to be activation of the renin-angiotensin system with associated potent antinatriuretic effects and/or the reduction in renal perfusion pressure (RPP) characteristic of heart failure. The present study was designed to examine the relative role of these two factors in mediating the blunted response to ANF in a model of acute low output heart failure produced by thoracic inferior vena cava constriction (TIVCC) in the anesthetized dog. TIVCC was produced in five groups of dogs. In group 1, ANF was infused after TIVCC to document the blunted natriuretic response. In group 2, ANF was infused after TIVCC in the presence of blockade of intrarenal angiotensin II (ANG II) by the intrarenal infusion of saralasin (Sar) at a dose without systemic effects. In group 3, ANF was infused after TIVCC in the presence of restoration of RPP by infusion of ANG II at a dose titrated to restore RPP to the level present before TIVCC. In group 4, ANF was infused in the presence of restoration of RPP with ANG II and blockade of intrarenal ANG II with Sar. Group 5 served as an additional control group where the effect of ANG II and Sar in TIVCC was examined in the absence of ANF. Restoration of RPP but not blockade of intrarenal ANG II resulted in a restoration of the response of sodium excretion and glomerular filtration rate to ANF. ANG II plus Sar in the absence of ANF did not produce a natriuresis. We conclude that RPP, more than intrarenal ANG II, modulates the blunted renal response to ANF observed in this model of acute low-output heart failure.

Animals↗
PubMed1989

Failure of atrial natriuretic factor to increase with volume expansion in acute and chronic congestive heart failure in the dog.

It remains unclear whether the levels of atrial natriuretic factor (ANF) observed in chronic CHF are appropriate for the magnitude of elevations in atrial pressures. Specifically, it is not known whether acute increases in atrial pressure in CHF can result in further significant increases in circulating ANF. The present study was designed to test the hypothesis that in chronic CHF there is an attenuated relation between circulating ANF and atrial pressure such that the heart is unable to respond to further increases in atrial pressure with appropriate increases in ANF. Cardiovascular hemodynamics and plasma levels of ANF were measured at baseline and after rapid right ventricular pacing (RRVP) to produce acute (n = 10, 25 minutes RRVP) and chronic (n = 7, 14-16 days RRVP) CHF. Acute saline volume expansion was then performed in each group to determine the response of circulating ANF to acute increases in atrial pressure in both acute and chronic CHF. In chronic CHF, right atrial pressure was much higher than in acute CHF (8.5 +/- 0.9 vs. 3.4 +/- 1.3 mm Hg, p less than 0.05); however, circulating ANF was not greater in chronic as compared with acute CHF (385 +/- 73 vs. 500 +/- 89 pg/ml), which is consistent with an attenuated release of ANF in chronic CHF. In response to volume expansion, right atrial pressure increased in both acute (3.4 +/- 1.3 to 12.1 +/- 7 mm Hg) and chronic (8.5 +/- .9 to 13.3 +/- 1.0 mm Hg) CHF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Role of endogenous atrial natriuretic factor in acute congestive heart failure.

The current studies were designed to investigate the functional significance of elevated endogenous atrial natriuretic factor (ANF) in acute congestive heart failure (CHF). Integrated cardiorenal and endocrine function were measured in three models of acute low-output congestive heart failure with comparably reduced cardiac output (CO) and mean arterial pressure (MAP). Acute CHF was produced by rapid right ventricular pacing (group I, n = 5) which decreases CO and increases atrial pressures and plasma ANF. In group II, n = 5, thoracic inferior vena caval constriction (TIVCC) was produced to decrease venous return and CO but without increases in atrial pressure or plasma ANF. In group III, n = 5, TIVCC was performed and exogenous ANF infused to achieve plasma concentrations observed in acute CHF. In acute CHF with increases in endogenous ANF, sodium excretion (UNaV), renal blood flow (RBF), plasma renin activity (PRA), and plasma aldosterone (PA) were maintained despite decreases in CO and MAP. In contrast, TIVCC with similar reductions in CO and MAP but without increases in ANF resulted in decreases in UNaV and RBF and increases in PRA and PA. Exogenous administration of ANF in TIVCC to mimic levels in acute CHF prevented sodium retention, renal vasoconstriction, and activation of renin and aldosterone. These studies demonstrate that endogenous ANF serves as an important physiologic volume regulator in acute CHF to maintain sodium excretion and possibly participate in the suppression of activation of the renin-angiotensin-aldosterone system despite the stimulus of arterial hypotension.

Aldosterone↗