Right ventricular function in an operating room model of mechanical left ventricular assistance and its effects in patients with depressed left ventricular function

Approximately 20% of patients who receive left ventricular assist devices (LVADs) for refractory cardiac failure after open heart surgery have had complications of right ventricular failure. To evaluate this problem in the diseased heart we simulated an LVAD in the operating room by bypassing and unloading the left ventricle with the heart-lung machine before routine open heart surgery. Right ventricular function was assessed in 12 patients with preoperative left ventricular ejection fractions of less than 0.55 (poor left ventricular function) (mean +/- SEM 0.40 +/- 0.03) and 10 patients with ejection fractions greater than 0.55 (normal left ventricular function) (0.63 +/- 0.02). Measurements before and during left ventricular bypass in the normal left ventricular function group revealed no change in cardiac output (from 5.7 +/- 0.6 to 5.8 +/- 0.4 liters/min), with a decrease in right ventricular end-diastolic pressure (from 8 +/- 2 to 6 +/- 1 mm Hg). However, in the poor left ventricular function group, cardiac output was increased significantly during left ventricular bypass from 4.5 +/- 0.2 to 5.3 +/- 0.4 liters/min and right ventricular end-diastolic pressure was decreased significantly from 13 +/- 2 to 8 +/- 2 mm Hg. During bypass there were significant reductions in mean pulmonary arterial pressure from 17 +/- 3 to 10 +/- 2 mm Hg in the normal left ventricular function group and from 27 +/- 3 to 12 +/- 2 mm Hg in the poor left ventricular function group. These measurements reflect passive changes in pulmonary pressures due to reductions in left ventricular filling pressure during left ventricular bypass.(ABSTRACT TRUNCATED AT 250 WORDS)     

Expression of specific granule markers on the cell surface of neutrophil cytoplasts

The widespread assumption that cytoplasts generated from human polymorphonuclear leukocytes (PMNs) are vesicles consisting solely of cytoplasm surrounded by plasma membrane and devoid of granule activity remains to be tested. PMN cytoplasts were prepared by centrifugation of intact cells on a Ficoll step gradient in the presence of cytochalasin B. Two granule membrane markers, Mol, a fluorometrically detectable antigen, and cytochrome b, both of which have been shown to translocate to the plasma membrane during granule release, were compared for their activity in cytoplasts and intact PMNs. We found that the amount of Mol detected on the plasma membrane of intact PMNs, as compared with other membrane markers (such as antigens LFA-1 and beta 2m), increased 1.6- fold upon exposure of PMNs to Ficoll plus cytochalasin B prior to centrifugation. Another twofold increase in Mol expression occurred upon cytoplast preparation. Release of the granule enzymes, vitamin B12- binding protein, and lysozyme were also followed and correlated well (r = .78 and .92) with the amount of Mol antigen present on the cell surface. Cytochrome b was also found to be higher (1.4-fold) on plasma membranes isolated from cytoplasts than on plasma membranes isolated from intact control cells. These results indicate that some fusion of granule membranes and plasma membranes occurred during treatment of PMNs with Ficoll plus cytochalasin b and during cytoplast preparation.     

Myelostimulatory activity of recombinant human interleukin-2 in mice

In a series of studies designed to extend our understanding of interleukin-2 (IL-2) and to study the effect of biologic response modifiers on bone marrow, we observed that administering recombinant human (rH) IL-2 to normal mice resulted in an increase in the frequency of colony-forming units-culture (CFU-C) in bone marrow. In addition, rH IL-2 was able to accelerate host recovery from cyclophosphamide (CTX)- or radiation-induced bone marrow depression and peripheral blood leukopenia. Not only can rH IL-2 accelerate, in a dose-dependent manner, the return of bone marrow, peripheral blood cellularity, and CFU-C frequency to normal levels following cytoreduction by CTX or irradiation, but it also significantly increases CFU-C frequency to greater than normal levels. Furthermore, rH IL-2 can significantly prolong survival of animals receiving a lethal dose of irradiation or CTX. Thus, multiple mechanisms are responsible for the synergistic therapeutic activity associated with rH IL-2 and CTX. rH IL-2 does not act only as an immunomodulatory agent in the presence or absence of suppressor T cells, but also accelerates host recovery from cytoreductive agents, resulting in decreased leukopenia and perhaps resistances to secondary infection. Thus, rH IL-2 plus chemotherapy may increase therapeutic activity against neoplastic disease, not only by adding immune stimulation to the direct antitumor effect of the drug but also by allowing delivery of higher, more effective doses of chemotherapy.     

The specificity of family history of alcohol and drug abuse in cocaine abusers

This study addresses the issue of whether the increased rates of substance-related problems for family members of cocaine abusers are specific for each substance. The present analysis examined the prevalence of problems due to alcohol or drug use separately for mothers, fathers, sisters, and brothers using the Family History Assessment Module. The probands were 343 out-of-treatment subjects with DSM-III-R cocaine disorders who did or did not have additional alcohol and opiate disorders. After accounting for age, race, gender, and antisocial personality, family history of alcohol-related problems had an odds ratio of 1.6 (p <.05) if a participant was alcoholic in addition to abusing cocaine. Specifically, a significantly greater proportion of participants' sisters (p <.001) and brothers (p <.05) had alcohol-related problems if the participant had a history of alcoholism. Among probands who reported opiate abuse or dependence, 38% had relatives with drug-related problems, while participants without opiate abuse or dependence had less than 31% of relatives with drug-related problems (p <.05). However, this association with opiate abuse or dependence and family history of drug-related problems was non-significant after controlling for participants' age, race, gender, treatment status, and antisocial personality diagnosis (odds ratio = 1.4, 95% C.I. = 0.8-2.4). Associations between participants' alcoholism and first-degree relatives' drug-related problems (and vice versa) showed that participants' history of opiate addiction did improve prediction of first-degree relatives' alcohol-related problems, except for participants' brothers. Additional familial risks for alcoholism were seen among siblings of drug abusers who also reported abuse of or dependence on alcohol even after controlling for relatives' ages. Furthermore, parental prevalence of alcohol-related problems were greater when participants had opiate addiction in addition to cocaine addiction. This seems to indicate that opiate addiction in addition to cocaine addiction has particularly strong inheritance patterns. In contrast, parental prevalence of drug-related problems was not greater when participants had alcohol addiction in addition to cocaine addiction. Thus, the cross-substance parent-child familial risk is limited to the dually diagnosed illicit drug.     

Ectopic expression of rhombotin-2 causes selective expansion of CD4-CD8- lymphocytes in the thymus and T-cell tumors in transgenic mice

Although the proto-oncogene rhombotin-2 (RBTN-2) is widely expressed in most tissues, it is not expressed in T cells. We investigated the potential for overexpression of RBTN-2 to cause tumors in T cells and other tissues by constructing transgenic mice that expressed RBTN-2 under control of the metallothionein-1 promoter. Despite overexpression of RBTN-2 in all tissues, transgenic mice developed T-cell tumors only, thus indicating that tumorigenesis caused by RBTN-2 is T-cell-specific. Thymic tumors were found between 37 and 71 weeks and were invariably associated with metastasis to nonlymphoid organs. Thymuses from apparently healthy transgenic mice were also examined. In some mice there was an 10-fold increase in the CD4-CD8- thymocyte subset, yet the total number of thymocytes was the same as that in wild-type mice. Thymic homeostasis was maintained by a compensatory reduction in the CD4+CD8+ subset. The expansion of CD4-CD8- thymocytes was associated with increased expression of RBTN-2 and with increased cell proliferation. No differences were found in the proportion of thymocytes undergoing apoptosis in transgenic mice. Furthermore, RBTN-2- induced expansion of CD4-CD8- cells did not block differentiation of these cells. Thymuses with 30% CD4-CD8- cells were essentially monoclonal, indicating that all thymic immunophenotypes were derived from a single clone. Overall, our data are consistent with the following scenario: (1) RBTN-2 expression in T cells causes selective and polyclonal proliferation of CD4-CD8- thymocytes accompanied by a compensatory decrease in other thymocyte subsets; (2) a clone with growth advantage and differentiation potential is selected and populates the thymus; and (3) this clone eventually breaches homeostasis of the thymus, accompanied or followed by metastasis to other organs.     

Modulation of megakaryocytopoiesis by thrombopoietin: the c-Mpl ligand

We have further characterized the biological activities, mechanism of action, and target cell populations of recombinant human and murine thrombopoietin (rhTPO and rmTPO) in in vitro human and murine model systems. Alone, hTPO or mTPO stimulated the maturation of immature murine megakaryoblasts as measured in a single cell assay. The combination of hTPO or mTPO and interleukin-6 (IL-6) resulted in a further increase in megakaryocyte differentiation in this system. Murine TPO stimulated mouse megakaryocyte progenitor development. Human megakaryocyte progenitor development was potentiated by hTPO alone and further augmented in the presence of the early-acting cytokines (IL-3) or kit ligand/stem cell factor (KL/SCF). To further define the mechanism of action of TPO, neutralization studies were performed with antisera to IL-3, granulocyte-macrophage colony-stimulating factor (GM- CSF), IL-1 beta, and IL-11. No diminution in TPO activity was observed in the presence of these antisera. Moreover, because adhesive interactions are known to modulate hematopoiesis, we studied whether hTPO might alter such interactions between human bone marrow (BM) megakaryocytes and human BM stromal fibroblasts. No changes were observed in either megakaryocyte expression of the surface molecules lymphocyte function-associated antigen-1, very late activation antigen- 4, or intercellular adhesion molecule-1 or the adhesion of megakaryocytes to stromal fibroblasts after treatment with the growth factor. Furthermore, no induction of secretion of the cytokines IL-1 alpha, IL-1 beta, GM-CSF, IL-6, granulocyte-CSF, tumor necrosis factor- alpha, transforming growth factor-beta 1, or transforming growth factor- beta 2 by primary human BM megakaryocytes was noted after treatment of the cells with hTPO. To address whether TPO affects very primitive hematopoietic progenitors, we studied the residual cells from the BMs of mice treated with high doses of 5-fluorouracil. Although no effect of mTPO alone was noted on the viability or replication of such primitive murine progenitor populations, the triple combination of IL-3 + KL/SCF + TPO stimulated growth of megakaryocyte progenitors. These results indicate that TPO is a highly lineage-specific growth factor whose primary biological effects are likely to be direct modulation of the growth and maturation of committed megakaryocyte precursors and immature megakaryoblasts.     

Phase I trial of interleukin-2 after unmodified HLA-matched sibling bone marrow transplantation for children with acute leukemia

Allogeneic bone marrow transplantation (BMT) for advanced acute leukemia is associated with a high risk of relapse. It is postulated that interleukin-2 (IL-2) administered after BMT might induce or amplify a graft-versus-leukemia effect and thereby reduce the relapse rate. To identify an IL-2 regimen for testing this hypothesis, a phase I trial of IL-2 (Roche) was performed in children in complete remission (CR) without active graft-versus-host disease (GVHD) off immunosuppressive agents after unmodified allogeneic matched-sibling BMT for acute leukemia beyond first remission. Beginning a median of 68 days after BMT, 17 patients received escalating doses of induction IL-2 (0.9, 3.0, or 6.0 x 10(6) IU/m2/d representing levels I, II, and III) for 5 days by continuous intravenous infusion (CIV). After 6 days of rest, they received maintenance IL-2 (0.9 x 10(6) IU/m2/d) for 10 days by CIV infusion. Levels I and II were well-tolerated, but, of 6 patients at level III, 1 developed pulmonary infiltrates, 1 developed hypotension (both resolved), and 1 died of bacterial sepsis and acute respiratory distress syndrome. Grade II acute GVHD developed in 1 patient at level I and 1 at level III. The maximum tolerated dose of induction IL-2 was level II. IL-2 induced lymphocytosis, with an increase in CD56+ and CD8+ cells. Ten patients remain in CR at 5+ to 67+ months. Thus, a regimen of IL-2 has been identified that did not induce a high incidence of acute GVHD when administered to children after unmodified allogeneic BMT. Its clinical activity will be assessed in a phase II trial.     

Psychiatric Disorders Among Drug Dependent Subjects: Are They Primary or Secondary?

The relationship between substance use disorders and comorbid psychiatric conditions was investigated among 425 persons in drug treatment who met DSM-III-R criteria for drug dependence. Using the NIMH Diagnostic Interview Schedule to ascertain DSM-III-R psychiatric disorders among these drug dependent subjects, lifetime prevalence rates were 64% for alcohol abuse/dependence, 44% for antisocial personality disorder, 39% for phobic disorders, 24% for major depression, 12% for dysthymia, and 10% for generalized anxiety disorder. We found that antisocial personality disorder and phobias generally had onsets prior to the onset of drug dependence (that is, they were primary disorders). The majority of drug dependent persons with generalized anxiety disorder reported an onset after the onset of drug dependence (that is, they had secondary generalized anxiety). Alcohol dependence, depression, and dysthymia were divided nearly evenly between earlier (primary disorder) and later (secondary disorder). These results are consistent with the body of literature indicating the importance of antisocial syndromes in the etiology of substance abuse and the literature indicating the complex, varying nature of the relationship of psychiatric disorders to substance dependence. Finally, a precise nomenclature for "age of onset," "primary," and "secondary" was developed for this study that is critical to understanding these issues and is recommended for other studies.     

Right heart function during left heart assist and the effects of volume loading in a canine preparation

A significant fraction of patients in whom mechanical left ventricular assist devices are implanted for refractory cardiac failure after open heart surgery have had the complication of right heart failure. To evaluate the effects of left ventricular assistance and pressure unloading on right ventricular function, we performed experiments in the normal hearts of open-chest, anesthetized, large mongrel dogs. We compared right ventricular function before and after left ventricular-to-aortic bypass with a roller pump at right atrial pressure levels of 1, 3, 5, and 7 mm Hg produced by volume loading. No significant changes were found in cardiac output or stroke volume over this range of right atrial pressures when comparing that before to that during left ventricular bypass, which at a right atrial pressure of 1 mm Hg reduced peak left ventricular pressure from 96 +/- 6 to 15 +/- 9 mm Hg and at a right atrial pressure of 5 mm Hg reduced it from 113 +/- 3 to 29 +/- 12 mm Hg, while maintaining aortic pressure. There was no evidence of right ventricular failure under these conditions: (from before to during bypass) at a right atrial pressure of 1 mm Hg cardiac output was 3.4 +/- 0.4 to 3.7 +/- 0.6 liter/min and stroke volume was 28 +/- 5 to 33 +/- 6 ml; during volume loading at a right atrial pressure of 7 mm Hg cardiac output was 5.6 +/- 0.6 to 5.7 +/- 0.7 liter/min and stroke volume was 47 +/- 5 to 52 +/- 5 ml.(ABSTRACT TRUNCATED AT 250 WORDS)     

Infection with Hemotropic Mycoplasma Species in Patients with or without Extensive Arthropod or Animal Contact

PCR amplification targeting the 16S rRNA gene was used to test individuals with and without extensive arthropod and animal contact for the possibility of hemotropic mycoplasma infection. The prevalence of hemotropic mycoplasma infection (4.7%) was significantly greater in previously reported cohorts of veterinarians, veterinary technicians, spouses of veterinary professionals, and others with extensive arthropod exposure and/or frequent animal contact than in a previously reported cohort of patients examined by a rheumatologist because of chronic joint pain or evidence of small-vessel disease (0.7%). Based upon DNA sequence analysis, a Mycoplasma ovis-like species was the most prevalent organism detected; however, infection with “Candidatus Mycoplasma haematoparvum” and a potentially novel, but incompletely characterized, hemotropic Mycoplasma species was also documented. Historical exposure to animals and arthropod vectors that can harbor hemotropic Mycoplasma spp. should be considered during epidemiological investigations and in the evaluation of individual patients.