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Biomedical subjects

S R Kurtz

Publications and source records attributed to S R Kurtz.

13 recordsLinked to original sources

Reducing the risk for transfusion-transmitted cytomegalovirus infection.

OBJECTIVE: To define the groups of patients at risk for transfusion-transmitted cytomegalovirus infection and to define the methods to reduce this risk. DATA SOURCES: English-language publications on transfusion medicine. STUDY SELECTION AND DATA EXTRACTION: Studies were selected that described cytomegalovirus infection in transfusion-dependent patients. Special attention was paid to reports that included observations about the prevalence and clinical manifestations of cytomegalovirus infection and recommendations for the prevention of infection. DATA SYNTHESIS: Some patients with impaired immune responses who have never been exposed to cytomegalovirus are at risk for transfusion-transmitted cytomegalovirus infection. This infection, which is associated with substantial morbidity and mortality, can be avoided by additional screening of blood donors or by special processing of components for transfusion. CONCLUSIONS: Transfusion products that are unlikely to transmit cytomegalovirus infection can be prepared by filtration to remove leukocytes or can be obtained by selecting donors who are seronegative for antibodies to cytomegalovirus. These products are indicated for certain groups of immunosuppressed patients, including pregnant women who are cytomegalovirus seronegative, premature infants of low birth weight who are born to cytomegalovirus-seronegative mothers, cytomegalovirus-seronegative recipients of allogeneic bone marrow transplants from cytomegalovirus-seronegative donors, and cytomegalovirus-seronegative patients with the acquired immunodeficiency syndrome (AIDS).

Cytomegalovirus Infections

Failure to detect extremely high levels of serum IgE with an immunoradiometric assay.

Two patients with extreme elevations in serum IgE were found to have falsely low levels of IgE when measured by a commercial immunoradiometric assay. Dilution studies performed on serum from both patients revealed the rise and subsequent fall of the dose-response curve characteristic of the high-dose "hook" or prozone effect. Specimens with unexpectedly low levels of serum IgE obtained by either commercial immunoradiometric assay or enzyme immunoassay should be reanalyzed after dilution.

Humans

Evaluation of a new microporous filtration membrane system for therapeutic plasma exchange.

A new therapeutic plasma exchange device developed by Sarns Inc./3M was evaluated in plasmapheresis of 20 healthy volunteers and in a multicenter clinical study of therapeutic plasma exchange that included 49 patients. Safety and efficacy of plasma separation from whole blood were assessed for a module that contains Durapore microporous surfactant-free polyvinylidene fluoride membrane (Millipore Corp., Bedford, Mass., USA). The extra-corporeal volume was 80 ml. Citrate and heparin anticoagulants were utilized. Mean plasma separation efficiency was 62% with unhindered passage of plasma proteins through the membrane pores and no hemolysis or activation of complement as measured by total hemolytic complement (CH50) and C3 conversion. Mean decrease in platelet count after procedures was 10%. No severe reactions occurred, and citrate effects (13%) were comparable to values reported with centrifugal instruments. The Sarns Inc./3M Therapore device is a rapid, safe and efficient system for plasma exchange and potentially for source plasma collection. The principal benefits are small extracorporeal volume and cell-free filtrate.

Citrates

Clinical utility of oncofetal proteins and hormones as tumor markers.

This article reviews the two most common hormones that act as tumor markers, human chorionic gonadotropin (HCG) and prolactin, and the two most common oncofetal proteins, carcinoembryonic antigen (CEA) and alpha-feto-protein (AFP). Assays for these markers are discussed in terms of their methodologies and performance in the clinical setting.

Adult

Accuracy and reproducibility of the AutoMicrobic System Gram-Negative General Susceptibility-Plus Card for testing selected challenge organisms.

A total of 180 selected strains of gram-negative bacilli were tested for susceptibility to nine antibiotics by the prototype General Susceptibility Card and reference broth microdilution MIC method, and 112 of 180 were tested by the modified Gram-Negative General Susceptibility-Plus Card (Vitek Systems, Inc., Hazelwood, Mo.). When category calls--susceptible, intermediate, and resistant for the prototype card and very susceptible, moderately susceptible, and resistant for the modified card--were identical or compatible (very susceptible by one method and moderately susceptible by the other), the methods were considered in qualitative or categorical agreement. The overall categorical agreement improved from 83% for the prototype card to 91.5% for the modified card, and the frequency of major and very major disagreements was reduced from 7.5 to 1%, respectively. Overall agreement between the modified card and reference method for both category calls and MICs (+/- 2 dilutions) was 90%. Of the results, 67% were identical, 22% were more susceptible with the modified card, and 11% were more resistant. Reproducibility of identical or compatible category calls and MICs obtained from three trials was 94.5%. The poorest accuracy and reproducibility were observed when testing Pseudomonas aeruginosa. The study suggests that the modified card can rapidly and efficiently perform susceptibility tests with an acceptable level of accuracy and reproducibility provided that the system is appropriately used for testing strains of the family Enterobacteriaceae with preset criteria for excluding organism-antibiotic combinations. The evaluation also indicates dramatic improvement in the technical performance of the modified card compared with its earlier prototype.

Anti-Bacterial Agents

Cytotaxins after the sedimentation behavior of human granulocytes.

Human granulocytes from the peripheral blood of healthy donors were subjected to transient gravity sedimentation analysis in Ficoll density gradient columns (37 degrees C) containing different concentrations of Escherichia coli endotoxin-activated serum and medium 199. A dramatic serum concentration-dependent dispersion of the cells based on changes in sedimentation velocity was observed as a function of time, using a new optical scanning instrument. The phenomenon was virtually abolished in the presence of cytochalasin B, a known inhibitor of cellular chemotaxis. The width (second statistical moment) of the sedimenting cell distribution increased in a sigmoid fashion as a function of time regardless of cytotaxin concentration. This indicates that a slow and nonlinear response of the granulocytes to the cytotaxins occurs. This new kinetic method should be useful in examining an alternate manifestation of the chemoresponsiveness of phagocytic cells and of cell interactions in general.

Bacterial Toxins

The immunocompetence of residual lymphocytes at various stages of red cell cryopreservation with 40% w/v glycerol in an ionic medium at -80 C.

Potentially immunocompetent cells have been found in washed liquid-stored red blood cells, in washed liquid-stored red blood cells to which a 40% W/V glycerol concentration was added, and in washed red blood cells freeze-preserved with 40% W/V glycerol at -80 C. A glycerol concentration of 40% W/V in an ionic medium, in addition to its cryoprotective effect on red blood cells, has a damaging effect on leukocytes. The freeze-thaw-wash process appears to produce the most damage to leukocytes and the remaining lymphocytes can be categorized into two groups: one that is capable of responding to phytohemagglutinin (PHA), and one that is not. Our study confirmed the presence of PHA-responsive lymphocytes in red blood cells freeze-preserved with 40% W/V glycerol in an ionic medium at -80 C. Although the relative proportions of these cells were variable and the results of the study somewhat erratic, we continue to recommend that liquid-preserved and freeze-preserved red blood cells be irradiated before transfusion to patients in whom graft-versus-host disease is a possible complication.

Blood Preservation

Factors that influence the process of 51chromium labeling of human granulocytes isolated from blood by counterflow centrifugation.

The uptake of 51chromium by human granulocytes isolated from blood by counterflow centrifugation is influenced by the composition of the suspension medium, the incubation period, the temperature and the amount of 51chromium used. Counterflow centrifugation-elutriation isolated approximately 98 per cent of the granulocytes from the blood. Acid-citrate-dextrose (ACD) plasma, citrate-phosphate-dextrose (CPD) plasma and heparinized plasma as resuspension media produced similar labeling results, whereas phosphate-buffered saline resulted in three times greater uptake in 51chromium. The greatest uptake of 51chromium (4%) was achieved after incubation of 37 C for one hour in autologous plasma, and granulocyte integrity and metabolic function in vitro were not adversely affected.

Blood Glucose

Dexamethasone.

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Dexamethasone