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Biomedical subjects

S E Lind

Publications and source records attributed to S E Lind.

At least 37 records · Page 2Linked to original sources
PubMed1991

Oncologists vary in their willingness to undertake anti-cancer therapies.

Previous studies have shown that groups of cancer sub-specialists differ in their stated willingness to undergo treatment for diseases lying within their area of expertise. In order to learn whether oncologists feel similarly about other forms of cancer, medical, radiation, and surgical oncologists were asked to fill out a questionnaire indicating whether they would be willing to undergo either chemotherapy or radiation therapy for a variety of common malignancies, or recommend them to a spouse or sibling. Subjects were also asked whether they would undertake an experimental therapy (interleukin-2) for any of three malignancies, or recommend such treatment to a spouse or relative. Fifty-one oncologists (14 radiation oncologists, 14 surgical oncologists, and 23 medical oncologists) were recruited from the staff of four university teaching hospitals. Although they agreed about accepting or declining therapy for some examples, there was considerable heterogeneity in their responses. In only 37% of the 30 cases involving standard therapies did greater than or equal to 85% of the oncologists agree that they would accept or refuse therapy. Only some of the variation of the responses could be attributed to the sub-specialty orientation of the oncologists. Physicians were as willing to recommend standard therapies for themselves as a spouse or sibling. Physicians were also divided in their opinion about whether they would accept a particular experimental therapy if diagnosed with one of three neoplasms. They were significantly more likely, however, to recommend it for a spouse or sibling than to accept it for themselves. Variation in the proportion of patients who receive anti-cancer therapies may relate, in part, to differences in opinion concerning the worth of such therapies among oncologists or primary physicians. This study shows that oncologists are quite heterogeneous with regard to their personal preferences for anti-cancer treatments for a variety of malignancies. Further studies are required to learn if such attitudes (among oncologists or primary physicians) directly affect the administration of such therapies.

Adult↗
PubMed1990

American oncology and the discourse on hope.

From the perspective of medical anthropology and comparative research, American oncology appears as a unique variant of international biomedical culture, particularly when contrasted with oncological practice in societies such as Japan and Italy. Based on interviews with 51 oncologists in Harvard teaching hospitals, this paper argues that American oncological practice draws on distinctive cultural meanings associated with "hope" and is infused with popular notions about the relationship between psyche and soma, the progressive efficacy of biotechnical interventions, truth-telling, and the nature of the physician-patient relationship.

Adult↗
PubMed1989

Apparent response of refractory post-transfusion purpura to splenectomy.

Post transfusion purpura (PTP) is a rare disorder characterized by the abrupt onset of severe thrombocytopenia following transfusion. A patient with PTP and massive bleeding was refractory to corticosteroids, gamma globulin, and plasma exchange but developed an immediate and sustained rise in platelet count following splenectomy. Splenectomy may be a useful therapeutic modality in patients with refractory PTP.

Aged↗
PubMed1989

Telling the diagnosis of cancer.

Although a concensus has emerged in this country that patients should be told when cancer is discovered, no data is available to indicate how and where patients are currently told that they have cancer. Fifty-five patients undergoing anticancer therapy were therefore interviewed to learn how this process occurs. The majority of patients were told by surgeons (74%) and only a minority by primary care physicians (11%). Most were told in a traditional medical setting (42% in the doctor's office, 17% in a hospital room), but 23% were told over the telephone and 19% in the recovery room. Two indicators of patient satisfaction with the telling process suggested that different sites of telling were not equivalent. Patients told over the telephone or in the recovery room were more likely to describe the telling in negative terms and less likely to describe their doctors as being helpful in understanding their illness than those told in a doctor's office or in their hospital bed. This pilot study indicates considerable variation in this aspect of patient care and suggests directions for future research. To determine whether interviews that explore these issues with cancer patients are unpleasant or stressful, patients' reactions to being subjects in this study were sought. Patients asked directly at the completion of the interview or surveyed 2 to 4 months later said the interview had been helpful and/or a positive experience. None expressed negative feelings about participating. Concerns about the psychological harm resulting from such study of this patient group do not appear to be warranted and should not impede future research.

Female↗
PubMed1988

Depression of gelsolin levels and detection of gelsolin-actin complexes in plasma of patients with acute lung injury.

Actin is the major protein of muscle and nonmuscle cells and is one of the most abundant body proteins. Physiologic or pathologic cell death may therefore result in the liberation of large amounts of this fibrous protein into the extravascular space. The potential for long actin filaments to increase plasma viscosity and change the rheology of the microvasculature are potentially obviated by the presence of 2 recently recognized plasma actin-binding proteins, vitamin-D-binding protein, and plasma gelsolin. As part of our initial evaluation of this newly recognized physiologic system in humans, we measured levels of gelsolin in plasma samples from patients with extensive lung injury. Gelsolin levels were depressed in 25 of 25 patients with the adult respiratory distress syndrome (ARDS), a disease characterized by massive cellular injury, as determined by either of 2 functional assays for gelsolin. Mean total gelsolin concentration of 20 patients with ARDS was 89.2 +/- 33 micrograms/ml (normal levels, approximately 240 micrograms/ml; p less than 0.001) and the mean free gelsolin concentration 69.6 +/- 29 micrograms/ml (normal levels, approximately 240 micrograms/ml; p less than 0.001). Gelsolin concentrations of 6 patients with bacterial pneumonias were also depressed, but to a lesser degree (mean total level, 117 +/- 21 micrograms/ml). Direct demonstration of the presence of actin in these plasmas (but not in normal plasmas) was performed by precipitating actin directly with DNase-Sepharose beads, or indirectly with antigelsolin-Sepharose beads, as confirmed with immunoblotting. Actin was found in 18 of 19 patients using DNase beads and in 7 of 19 using antigelsolin beads.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1988

Circulating actin-gelsolin complexes following oleic acid-induced lung injury.

Plasma gelsolin is one of two extracellular proteins that bind actin, a major body protein, with high affinity. The authors performed a series of experiments to determine whether tissue injury leads to actin release and the formation of circulating actin-gelsolin complexes. Two functions of plasma gelsolin, filament-nucleating and filament-severing activity, were used to measure total and free gelsolin concentrations, respectively. Both gelsolin and gelsolin-actin complexes nucleate actin assembly, whereas only free gelsolin severs actin filaments. Therefore, nucleation reflects the total gelsolin concentration, severing, the free gelsolin concentration, and the difference, gelsolin-actin complexes. Injection of F-actin in the rat caused a reduction in the free, but not total, gelsolin levels, consistent with the formation of circulating actin-gelsolin complexes. Oleic acid (50 mg/kg) administered intravenously in rats, a treatment that causes acute hemorrhagic pulmonary necrosis, caused the free gelsolin concentration to fall to a greater extent than the total gelsolin concentration, which indicated the presence of circulating actin-gelsolin complexes. Lower doses (9-27 mg/kg) in rabbits caused a qualitatively similar but smaller change in the free gelsolin level. Plasma gelsolin was immunoprecipitated at times when actin-gelsolin complexes were present, as determined functionally, and bound actin was demonstrated by immunoblotting with an anti-actin antiserum. These studies show that considerable amounts of actin are released into the extracellular space during acute lung injury and that circulating actin-gelsolin complexes can be detected in the peripheral blood.

Actins↗
PubMed1988

Decreased plasma gelsolin levels in patients with Plasmodium falciparum malaria: a consequence of hemolysis?

Mammalian plasma contains a high-affinity actin-binding protein, plasma gelsolin, that severs actin filaments. Destruction of erythrocytes could result in the release of erythrocyte cytoskeletal actin into the plasma where it could bind to gelsolin. If the clearance of actin-gelsolin complexes exceeds its synthesis, lowering of the plasma gelsolin concentration might follow. To test this hypothesis, we measured plasma gelsolin levels in patients with falciparum malaria, a disease where at least part of the hemolysis takes place in the intravascular space and that is usually not accompanied by dysfunction of other organs. Two functional gelsolin assays showed that the mean plasma gelsolin concentration of 18 Nigerian children with Plasmodium falciparum malaria was less than 50% (P less than .001) of healthy Nigerian control subjects tested at the same time. Patients with pneumonia and febrile seizures also had depressed gelsolin levels, which indicates that factors other than hemolysis can lower gelsolin concentrations. Gelsolin levels were measured in 11 patients from The Gambia with P falciparum malaria before and approximately 3 weeks after treatment. In all cases the gelsolin level increased after treatment. To confirm the hypothesis that hemolysis can result in a lowering of plasma gelsolin levels, hemolysis was induced in rabbits, either acutely (by the injection of human serum) or subacutely (by the administration of phenylhydrazine). A fall in plasma gelsolin levels was seen, the rate of fall differing with the extent of hemolysis. Affinity adsorption of plasma from animals undergoing acute hemolysis with Sepharose beads coupled to the actin-binding protein DNase I, followed by immunoblotting of adherent proteins with antiactin antiserum demonstrated the presence of actin in circulating rabbit plasma. These studies suggest that under some conditions components of the red cell cytoskeleton are exposed to plasma proteins and that accelerated clearance of actin-gelsolin complexes may explain in part the depressed plasma gelsolin levels seen in patients with falciparum malaria.

Actins↗
PubMed1988

Resolution of malignant ascites after intraperitoneal chemotherapy in women with carcinoma of the ovary.

The treatment of malignant ascites is a difficult task that faces the physician who is treating patients with advanced carcinoma. We describe the clinical course of three patients with malignant ascites caused by advanced carcinoma of the ovary who were treated with cisplatin-based intraperitoneal chemotherapy. In all three patients, there was resolution of the ascites with relief of symptoms caused by abdominal distention. Although one patient had a fall in the serum level of CA 125 (the antigen marker of carcinoma of the ovary) with repeated courses of intraperitoneal therapy, there was little reduction in the bulky abdominal tumors. Even though intraperitoneal chemotherapy, as currently administered, does not appear to effect a significant reduction in tumor in women with bulky carcinoma of the ovary, it may be of benefit in improving the quality of life. Larger numbers of patients should be studied to better assess the role of this method of treatment in the palliative cure of patients with symptomatic malignant ascites.

Aged↗
PubMed1987

Reversible binding of actin to gelsolin and profilin in human platelet extracts.

This paper documents the reversible appearance of high-affinity complexes of profilin and gelsolin with actin in extracts of platelets undergoing activation and actin assembly. Sepharose beads coupled to either monoclonal anti-gelsolin antibodies or to polyproline were used to extract gelsolin and profilin, respectively, from EGTA-containing platelet extracts and determine the proportion of these molecules bound to actin with sufficient affinity to withstand dilution (high-affinity complexes). Resting platelets (incubated for 30 min at 37 degrees C after gel filtration) contained nearly no high-affinity actin/gelsolin or actin/profilin complexes. Thrombin, within seconds, caused quantitative conversion of platelet profilin and gelsolin to high-affinity complexes with actin, but these complexes were not present 5 min after stimulation. The calcium-dependent actin filament-severing activity of platelet extracts, a function of free gelsolin, fell in concert with the formation of EGTA-stable actin/gelsolin complexes, and rose when the adsorption experiments indicated that free gelsolin was restored. The dissociation of high-affinity complexes was temporally correlated with the accumulation of actin in the Triton-insoluble cytoskeleton.

Actins↗
PubMed1987

Quantitative measurement of plasma gelsolin and its incorporation into fibrin clots.

Gelsolin is a newly recognized actin-binding protein of plasma that severs actin filaments. The concentration of plasma gelsolin was measured by three independent methods: an enzyme-linked immunosorbent assay (ELISA) and two functional assays based on the ability of gelsolin to accelerate the polymerization of actin (a "nucleating" assay) or to sever preformed actin filaments (a "cutting" assay). The gelsolin level in 56 samples of human plasma ranged between 100 and 330 micrograms/ml. The mean plasma concentrations measured by the different assays were ELISA, 207 micrograms/ml; nucleating assay, 233 micrograms/ml; cutting assay, 247 micrograms/ml. The mean serum level of gelsolin was found to be 24% lower than that of plasma when paired samples were examined (183 micrograms/ml). The difference between plasma and serum gelsolin concentrations can be accounted for by a direct interaction between gelsolin and fibrin as shown by the binding of radiolabeled gelsolin to clots made from purified fibrinogen. Further, unlabeled gelsolin inhibits the binding of the labeled species to fibrin, but hemoglobin and albumin do not. Fibrin oligomers, but not fibrinogen, alter the sedimentation characteristics of radiolabeled gelsolin in sucrose gradients. The amount of gelsolin incorporated into the clot is increased if the clots are made in the presence of actin filaments or fibronectin. Thus, serum levels of gelsolin are lower than plasma levels because of an interaction between gelsolin and fibrin clots.

Actins↗
PubMed1987

Capacity of human serum to depolymerize actin filaments.

Human blood depolymerizes filamentous (F-)actin. The interaction of actin filaments and monomers with human serum was studied by following the kinetics and extent of the depolymerization of pyrene-labeled F-actin and by analysis of serum proteins adhering to immobilized actin monomers. In physiologic Ca2+ concentrations, the depolymerization of F-actin proceeds in two stages: a rapid phase, attributed to direct severing of filaments by plasma gelsolin, and a slow phase attributed to the binding of actin monomers to vitamin D-binding protein (DBP). Without Ca2+, only the slow phase is observed. Human serum can completely depolymerize 10 to 18 mumol/L of actin, of which approximately 5 mumol/L occurs rapidly. Depolymerization can be accounted for by the normal serum concentrations of gelsolin and DBP. Fibrin(ogen) and fibronectin, which bind actin in vitro, do not contribute to the kinetics or extent of its depolymerization. Affinity chromatography and functional assays for the presence of gelsolin-actin complexes show that addition of G-actin to serum results in preferential formation of actin-DBP complexes, but that addition of F-actin to serum produces both gelsolin-actin complexes and DBP-actin complexes. The distinctive binding of actin monomers and polymers to these two serum proteins suggests a means by which their coordinated actions are maximized in vivo, from the standpoint of depolymerizing filaments and clearing monomers from the circulation.

Actins↗
PubMed1986

Sequential binding of actin monomers to plasma gelsolin and its inhibition by vitamin D-binding protein.

Functional studies that distinguish free from actin-bound gelsolin based on the ability of the former to sever actin filaments reveal that the binding of actin monomers to gelsolin is highly cooperative and can be prevented by prior incubation of actin with vitamin D-binding protein (DBP), even though the apparent affinity of gelsolin for actin is 50-fold greater than that of DBP. Measurements of actin binding by immunoprecipitation and pyrene-actin fluorescence establish that DBP-actin complexes do not bind to gelsolin and that DBP removes one of the actin monomers in a 2:1 actin-gelsolin complex. These studies may explain why DBP-actin complexes exist in blood plasma in vivo in the presence of free gelsolin and suggest that the interaction of gelsolin with actin in cells and plasma may be regulated in part by actin monomer binding proteins.

Actins↗
PubMed1986

Role of plasma gelsolin and the vitamin D-binding protein in clearing actin from the circulation.

We determined the plasma kinetics of both actin and complexes of actin with the two high affinity actin-binding proteins of plasma, gelsolin, and vitamin D-binding protein (DBP). Actin is cleared rapidly from the plasma by the liver (half-disappearance time, 0.5 h). Using radiolabeled actin-binding proteins, we found that actin accelerated the clearance of both plasma gelsolin and the vitamin D-binding protein. In separate experiments we found that DBP-actin complexes were cleared more quickly than gelsolin-actin complexes, at a rate comparable to the clearance of actin from the blood. A low affinity interaction (dissociation constant, 2.9 X 10(-4) M) between actin and fibronectin was found, suggesting that little actin will bind to fibronectin in plasma. We conclude that while plasma gelsolin and DBP may both clear actin from the circulation, DBP appears to play a more important role. By so doing, DBP may conserve the filament-severing activity of plasma gelsolin.

Actins↗
PubMed1986

Diagnosing liver metastases: a Bayesian analysis.

Clinicians frequently perform tests to determine whether patients have liver metastases. Optimal use of a laboratory test requires that the clinician know the test's operating characteristics (its sensitivity and specificity) and have an estimate of the pretest probability that disease is present. We have surveyed studies that examined the value of four biochemical and three imaging tests in establishing a diagnosis of hepatic metastases in patients who underwent an invasive procedure to establish the presence or absence of disease. We have pooled the data from these studies to arrive at values for the sensitivity and specificity of each of these tests, and calculated the predictive values for these tests over a wide range of pretest probabilities of disease. Several examples illustrate how this information may be used clinically. We provide a framework for the optimal interpretation of these commonly ordered tests and indicate the data needed for their complete analysis.

Bayes Theorem↗