An analysis of interobserver reliability and representativeness of data from the Veterans Affairs Cooperative Study on Processes, Structures, and Outcomes in Cardiac Surgery

The authors made some preliminary judgments regarding the reliability and representativeness of the data in the early stages of the Veterans Affairs Cooperative Study entitled Processes, Structures, and Outcomes of Care in Cardiac Surgery (PSOCS). Preliminary PSOCS interobserver reliability and potential patient and site selection bias reported were based on comparisons with identical risk, procedure, and outcome data items collected independently in the Continuous Improvement in Cardiac Surgery Study. PSOCS interobserver reliability for this limited set of variables was good to excellent. At the six pilot centers, there were few important differences between patients entered into PSOCS and those not entered. The 14 Veterans Affairs medical centers that will participate in the full-scale PSOCS study and the 29 nonparticipating centers exhibited similar patient populations. will be valuable.

Development of an interactive data base management system for capturing large volumes of data

Accurate collection and successful management of data are problems common to all scientific studies. For studies in which large quantities of data are collected by means of questionnaires and/or forms, data base management becomes quite laborious and time consuming. Data base management comprises data collection, data entry, data editing, and data base maintenance. In this article, the authors describe the development of an interactive data base management (IDM) system for the collection of more than 1,400 variables from a targeted population of 6,000 patients undergoing heart surgery requiring cardiopulmonary bypass. The goals of the IDM system are to increase the accuracy and efficiency with which this large amount of data is collected and processed, to reduce research nurse work load through automation of certain administrative and clerical activities, and to improve the process for implementing a uniform study protocol, standardized forms, and definitions across sites.

Inhibition of cis-diammine-1,1-cyclobutane dicarboxylatoplatinum(II)-induced DNA interstand cross-link removal and potentiation of cis-diammine-1,1-cyclobutane dicarboxylatoplatinum(II) cytotoxicity by hydroxyurea and 1-beta-D-arabinofuranosylcytosine

1-beta-D-Arabinofuranosylcytosine (ara-C) and hydroxyurea (HU) were investigated as potential DNA repair inhibitors with cis-diammine-1,1-cyclobutane dicarboxylatoplatinum(II) (CBDCA). HU plus ara-C, known inhibitors of DNA excision-repair, had previously been found to produce cytotoxic synergy and delayed removal of DNA interstrand cross-links with cis-diamminedichloroplatinum(II) (DDP). Since CBDCA and DDP share a common active intermediate, it should be possible to reproduce this interaction with CBDCA. However, the stable dicarboxylate chelate ring structure of CBDCA results in kinetics that differ significantly from those of DDP, due to slower hydrolysis to the active species. DNA adducts form more slowly, with interstand cross-links peaking approximately 12-h later and disappearing more gradually than in the case of DDP. It was therefore expected that a longer antimetabolite exposure might be required for repair inhibition with CBDCA. The 12-h exposure to HU plus ara-C previously found effective with DDP produced no cytotoxic synergy with a 2-h CBDCA exposure. Lengthening the antimetabolite treatment to 24 h resulted in approximately 1 log of synergistic toxicity, while a 24-h simultaneous exposure to HU, ara-C, and CBDCA resulted in 2 logs. Cells exposed to all three drugs showed a 2- to 3-fold greater level of interstrand cross-links after 36- to 48-h of incubation following drug removal, compared to CBDCA alone. Taken together, these findings suggest that HU plus ara-C modulates the repair of platinum-DNA adducts and establishes an effective in vitro schedule at clinically achievable concentrations for the use of those antimetabolites with CBDCA.

The effects of 16,16-dimethyl PGE2 and phosphodiesterase inhibitors on Con A blastogenic responses and NK cytotoxic activity of mouse spleen cells

Prostaglandins function as down regulators of immune responses probably by increasing the concentration of intracellular cAMP. Phosphodiesterase inhibitors, which prevent the breakdown of cAMP, also increase the intracellular levels of cAMP. Prostaglandins and phosphodiesterase inhibitors have both been shown to suppress immune responses in vitro. In this study 16,16-dimethyl PGE2 (dm-PGE2), added in vitro, suppressed the mouse spleen cell concanavalin A (Con A) response by 38% and natural killer (NK) activity by 53%. Addition of the phosphodiesterase inhibitors, theophylline, RO20-1724, or dipyridamole, decreased both the Con A response and NK activity by at least an additional 30%. We also demonstrate that treatment with dm-PGE2 and theophylline in vivo is more effective than either compound alone in inhibiting NK activity of both untreated mice and mice treated with polyinosinic-polycytidylic acid. These studies support the hypothesis that the immunosuppressive effect of dm-PGE2 is mediated by cAMP and suggest that treatment with a combination of dm-PGE2 and phosphodiesterase inhibitors can augment this immunosuppressive effect.

The effects of protein kinase inhibitors on lymphocyte blastogenesis and GVHD-induced splenomegaly

The activation of the protein kinase C (PKC) pathway plays an integral part in the proliferation of many cell types including lymphocytes. We report that the PKC inhibitor H-7 caused inhibition of three commonly studied blastogenic responses (Con A, LPS, and MLR) with the strongest suppression being detected in the MLR. In contrast, HA1004, a potent inhibitor of cyclic nucleotide-dependent protein kinases, did not alter the blastogenic response but occasionally caused augmentation. The phenothiazine compounds studied inhibited the Con A and, to a lesser extent, the LPS responses. One of the compounds, promethazine-HCl, was effective in vivo in inhibiting splenomegaly resulting from the induction of graft vs. host disease. Our studies support the involvement of PKC in lymphoid blastogenesis. They also suggest that agents that can inhibit PKC activity may be useful in inducing immunosuppression in vivo.

The effects of E series prostaglandins on blastogenic responses in vitro and graft vs. host responses in vivo

In this study the ability of prostaglandin E1 (PGE1), Misoprostol (a stable analog of PGE1), and 16,16-dimethyl PGE2 (a stable analog of PGE2) to suppress immune responses in vitro and in vivo was determined. All of the compounds caused a titratable (10(-6) to 10(-9) M) suppression of Con A blastogenesis and the mixed lymphocyte response whereas there was only slight inhibition of the LPS response. When either 16,16-dimethyl PGE2 (30 ug/mouse) or Misoprostol (60 ug/mouse) was administered daily in vivo, there was a significant suppression of splenomegaly in F1 mice (C57Bl/6 x CBA) which had been injected with parental (C57Bl/6) spleen cells. We conclude that prostaglandins of the E series can function as immunosuppressive reagents both in vitro and in vivo. In the future they may serve to augment existing forms of immunosuppressive therapy.

Stimulation of suppressor cells in the bone marrow and spleens of high dose cyclophosphamide-treated C57Bl/6 mice

Systemic administration of a single dose (300 mg/kg) of cyclophosphamide (Cy) induced the appearance of a population of suppressor cells in the bone marrow and spleens of mice. Suppressor cells were assayed by their capacity to inhibit the concanavalin A (Con A) blastogenesis or the mixed-lymphocyte response of normal C57Bl/6 spleen cells. Cy-induced bone marrow (Cy-BM) suppressor cells were present as early as 4 days following Cy therapy and their activity gradually decreased over the next 2 weeks. Cy-induced splenic (Cy-Sp) suppressor cells were maximally present on Days 6 through 10 following Cy therapy. Studies were performed to characterize the suppressor cells of bone marrow obtained 4 days after Cy treatment and of normal bone marrow (N-BM). Some suppressor activity was present in normal bone marrow. N-BM suppressor cells resembled cells of the monocyte/macrophage lineage in that they were slightly adherent to Sephadex G-10, sensitive to L-leucine methyl ester (LME), and insensitive to treatment either with anti-T-cell antibody and complement or with anti-immunoglobulin antibody and complement. Their suppressive activity was abrogated by incubation with either indomethacin or catalase. Cy-BM suppressor cells were also resistant to treatment with anti-T-cell and anti-immunoglobulin antibody and complement but were not adherent to Sephadex G-10 and not sensitive to LME. Their suppressive activity was partially eliminated by indomethacin alone or in combination with catalase. We conclude that Cy chemotherapy induces the appearance of a population of immune suppressive cells and that these cells appear first in the bone marrow and subsequently in the spleen.

Stimulation of hematopoiesis and bone marrow suppressor cells by the subcutaneous injection of linoleic acid

The effects of injection of linoleic acid into C57Bl/6 mice on hematopoietic and immunological parameters were examined. Administration of linoleic acid stimulated hematopoiesis as it increased spleen weight and cellularity, increased the number of bone marrow and splenic granulocytic-monocytic progenitor cells, and increased the colony stimulating factor activity in the serum of the treated mice. Associated with the hematopoietic stimulation in linoleic acid-treated mice was a decline in the spleen cell blastogenic responses and the appearance of bone marrow suppressor cells which were inhibitory to normal spleen cell blastogenesis. The linoleic acid-induced bone marrow suppressor cells resembled cells of the monocyte lineage in that they were sensitive to treatment with L-leucine methyl ester, partially sensitive to treatment with anti-Ia antibodies and complement, and their suppressor activity was minimized by indomethacin, a prostaglandin synthesis inhibitor. These results suggest that administration of linoleic acid results in hematopoietic stimulation and, concurrently, in the appearance of suppressor cells in the bone marrow. The bone marrow suppressor cells resemble immature cells of the monocyte lineage and appear to mediate their suppressive effects through the production of prostaglandins.

Stimulation of prostaglandin-dependent macrophage suppressor cells by the subcutaneous injection of polyunsaturated fatty acids

Polyunsaturated fatty acids (PUFAs), in the form of pure linoleic, linolenic, or arachidonic acid, were injected subcutaneously into male C57Bl/6 mice daily for 10 days. Injection of 3.6 mg/day of PUFA resulted in up to a two- to threefold increase in spleen weight. Spleen cell response to mitogens was reduced by about 70%; mixed lymphocyte responses were reduced by about 90% when compared to normal values. In admixture experiments, spleen cells from PUFA treated mice suppressed the mitogen induced blastogenic response of control spleen cells by up to 90%. Fractionation of spleen cells from PUFA treated mice by G-10 adherence resulted in an enrichment of suppressive activity in the adherent cells. The suppressive effect of G-10 adherent cells was abolished by the addition of indomethacin as well as by depletion of macrophages by treatments with agents such as carbonyl iron and leucine methyl ester. These studies indicate that the administration of PUFA has marked immunosuppressive effects in mice. These effects may be related to increased prostaglandin production and appear to be mediated by a macrophage type cell.

Stimulation of hematopoiesis in untreated and cyclophosphamide treated mice by the inhibition of prostaglandin synthesis

Indomethacin (IN) was administered to untreated or to cyclophosphamide (CY) treated C57B1/6 mice to study the roles of prostaglandins in regulating hematopoiesis. The following hematopoietic parameters were quantitated: peripheral blood leukocyte (PBL) count; total nucleated cells per spleen; total nucleated cells per femur; and spleen weight. Assays were performed in vitro to measure the number of colony forming units (CFU) present in the bone marrow and spleen. Untreated mice administered IN had a transient rise in their PBL count. These animals also developed splenomegaly and had an increased number of nucleated cells in their spleen. All CY treated mice had a marked decrease in PBL count, spleen cellularity, bone marrow cellularity, and spleen size during the first 5 days after CY treatment. These observations were followed by hematopoietic recovery over the next 10 days. Cyclophosphamide treated mice exhibited a more rapid hematopoietic recovery when treated with IN than without IN treatment. Analysis of the CFU capacity of bone marrow and spleen cells in soft agar showed a larger number of CFU in the bone marrow and spleen of IN treated mice or of CY/IN treated mice than in animals not receiving IN. These results indicate that prostaglandins are involved in the regulation of hematopoiesis in untreated mice and that prostaglandins may limit the hematopoietic recovery of CY treated mice.