Inhibition of factor XII in septic baboons attenuates the activation of complement and fibrinolytic systems and reduces the release of interleukin-6 and neutrophil elastase

In previous studies, we have shown that administration of monoclonal antibody (MoAb) C6B7 against human factor XII to baboons challenged with a lethal dose of Escherichia coli abrogates activation of the contact system and modulates secondary hypotension. To evaluate the contribution of activated contact proteases to the appearance of other inflammatory mediators in this experimental model of sepsis, we studied the effect of administration of MoAb C6B7 on activation of complement and fibrinolytic cascades, stimulation of neutrophil degranulation, and release of the proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Activation of the complement system, as reflected by circulating C3b/c and C4b/c levels, was significantly reduced in five animals that had received MoAb C6B7 before a lethal dose of E coli as compared with five control animals that had been given a lethal challenge only. Inhibition of contact activation also modulated the fibrinolytic response, since the release of tissue-type plasminogen activator (t-PA) and the appearance of plasmin-alpha2-antiplasmin (PAP) complexes into the circulation was significantly attenuated upon pretreatment with anti-factor XII MoAb. In contrast, plasma levels of plasminogen activator inhibitor (PAI) were modestly enhanced in the treatment group. Degranulation of neutrophils, as assessed by circulating elastase-alpha1-protease inhibitor complexes, and release of IL-6 but not of TNF-alpha was decreased in anti-factor XII-treated animals. Observed differences in the inflammatory response between treatment and control groups were not likely due to different challenges, since the number of E coli that had been infused, as well as circulating levels of endotoxin after the challenge, were similar for both groups. These data suggest that activation of the contact system modulates directly or indirectly various mediator systems involved in the inflammatory response during severe sepsis in nonhuman primates.     

Reduction of alpha-naphthylisothiocyanate-induced hepatotoxicity by recombinant human hepatocyte growth factor.

Hepatocyte growth factor (HGF) is a potent stimulator of DNA synthesis in cultured hepatocytes. To determine whether HGF has any activity in vivo, we have tested HGF in rats in which intrahepatic cholestasis was induced by acute administration of alpha-naphthylisothiocyanate (ANIT). The hepatotoxic effects of a single injection of ANIT were manifested 48 h later as large increases in serum bilirubin, alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase. These biochemical changes were accompanied by widespread periportal edema, hypertrophy of bile duct epithelium, and randomly scattered areas of liquifaction necrosis in the hepatic parenchyma. The increases in bilirubin, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were markedly attenuated when HGF was administered 30 min before ANIT and again at 6, 12, 24, 30, and 36 h after ANIT. In addition, this HGF dosing regimen completely prevented the occurrence of parenchymal lesions, although it had no effect on periportal histopathology. The effect of ANIT was dose dependent; a maximal response was observed at 320 micrograms/kg per injection, with an intermediate response at 105 micrograms/kg. Delaying the administration of HGF until 12 h after ANIT was as effective as when administration was begun 30 min before ANIT. Taken together these results show that HGF can prevent some aspects of ANIT hepatotoxicity.     

Diffuse large cell lymphoma in a patient with hairy cell leukemia: immunoglobulin gene analysis reveals separate clonal origins

A 75-year-old man with hairy cell leukemia (HCL) was found to have an immunoblastic lymphoma of the small bowel. Immunologic and genotypic characterization of these neoplasms revealed both the HCL and the immunoblastic lymphoma to be of the B cell lineage. The HCL expressed the HCL-associated antigens detected by the monoclonal antibodies HC-1 and HC-2, whereas the immunoblastic lymphoma failed to react with these antibodies. In addition, surface immunoglobulin light chains could not be accurately determined for the hairy cells, whereas the immunoblastic lymphoma was shown to express only kappa immunoglobulin light chains. These immunophenotype differences were compatible with either the clonal evolution of the HCL into the immunoblastic lymphoma or a separate clonal origin for these two neoplasms. An analysis of tumor DNA by Southern blot hybridization revealed different heavy-chain and kappa light-chain gene rearrangements in these two malignancies. Thus the occurrence of the large cell lymphoma most likely represents the emergence of a second clonally unrelated B cell malignancy.     

The value of flow cytometric analysis of platelet glycoprotein expression of CD34+ cells measured under conditions that prevent P- selectin-mediated binding of platelets

In the present study, we show by adhesion assays and ultrastructural studies that platelets can bind to CD34+ cells from human blood and bone marrow and that this interaction interferes with the accurate detection of endogenously expressed platelet glycoproteins (GPs). The interaction between these cells was found to be reversible, dependent on divalent cations, and mediated by P-selectin. Enzymatic characterization showed the involvement of sialic acid residues, protein(s). The demonstration of mRNA for the P-selectin glycoprotein ligand 1 (PSGL-1) in the CD34+ cells by polymerase chain reaction (PCR) analysis suggests that this molecule is present in these cells. Under conditions that prevent platelet adhesion, a small but distinct subpopulation of CD34+ cells diffusely expressed the platelet GPIIb/IIIa complex. These cells were visualized by immunochemical studies. Furthermore, synthesis of mRNA for GPIIb and GPIIIa by CD34+ cells was shown using PCR analysis. The semiquantitative PCR results show relatively higher amounts of GPIIb mRNA than of PF4 mRNA in CD34+CD41+ cells in comparison with this ratio in platelets. This finding is a strong indication that the PCR results are not caused by contaminating adhering platelets. MoAbs against GPIa GPIb alpha, GPV, P- selectin, and the alpha-chain of the vitronectin receptor did not react with CD34+ cells. The number of CD34+ cells expressing GPIIb/IIIa present in peripheral blood stem cell (PBSC) transplants was determined and was correlated with platelet recovery after intensive chemotherapy in 27 patients. The number of CD34+CD41+ cells correlated significantly better with the time of platelet recovery after PBSC transplantation (r = .83, P = .04) than did the total number of CD34+ cells (r = .55). Statistical analysis produced a threshold value for rapid platelet recovery of 0.34 x 10(6) CD34+CD41+ cells/kg. This study suggests that if performed in the presence of EDTA the flow cytometric measurement of GPIIb/IIIa on CD34+ cells provides the most accurate indication of the platelet reconstitutive capacity of the PBSC transplant.     

Maintenance of murine long-term repopulating stem cells in ex vivo culture is affected by modulation of transforming growth factor-beta but not macrophage inflammatory protein-1 alpha activities

Transforming growth factor-beta (TGF-beta) and macrophage inflammatory protein-l alpha (MIP-1 alpha) are both well-described inhibitors of committed and multipotential hematopoietic progenitors. The effect of these cytokines; on true stem cell activity in ex vivo culture systems as assayed by murine long-term repopulating activity (LTRA) has not been examined. We studied the stem cell effects of the addition of these cytokines to ex vivo cultures containing interleukin-3 (IL-3), IL- 6, and stem cell factor (SCF), using the murine competitive repopulation assay. We also tested the impact of adding an anti-TGF- beta neutralizing antibody, to ask whether abrogation of autocrine/paracrine TGF-beta may protect or enhance the survival of LTRA during ex vivo culture. TGF-beta 1 had significant suppressive effects on both short- and long-term repopulating activities, and anti- TGF-beta antibody had enhancing effects compared with control cultures containing IL-3, IL-6, and SCF alone. MIP-1 alpha had no significant effects on either short- or long-term repopulating ability. These data suggest that abrogation of TGF-beta during suspension culture may allow enhanced survival or even expansion of primitive cells ex vivo, with implications for many applications, including gene therapy.     

Influence of clinical status on the association between plasma total and unbound bilirubin and death or adverse neurodevelopmental outcomes in extremely low birth weight infants

Objectives: To assess the influence of clinical status on the association between total plasma bilirubin and unbound bilirubin on death or adverse neurodevelopmental outcomes at 18–22 months corrected age in extremely low birth weight infants. Method: Total plasma bilirubin and unbound bilirubin were measured in 1101 extremely low birth weight infants at 5 ± 1 days of age. Clinical criteria were used to classify infants as clinically stable or unstable. Survivors were examined at 18–22 months corrected age by certified examiners. Outcome variables were death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death prior to follow‐up. For all outcomes, the interaction between bilirubin variables and clinical status was assessed in logistic regression analyses adjusted for multiple risk factors. Results: Regardless of clinical status, an increasing level of unbound bilirubin was associated with higher rates of death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss and death before follow‐up. Total plasma bilirubin values were directly associated with death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death before follow‐up in unstable infants, but not in stable infants. An inverse association between total plasma bilirubin and death or cerebral palsy was found in stable infants. Conclusions: In extremely low birth weight infants, clinical status at 5 days of age affects the association between total plasma bilirubin and death or adverse neurodevelopmental outcomes at 18–22 months of corrected age. An increasing level of UB is associated a higher risk of death or adverse neurodevelopmental outcomes regardless of clinical status. Increasing levels of total plasma bilirubin are directly associated with increasing risk of death or adverse neurodevelopmental outcomes in unstable, but not in stable infants.     

Bone marrow disorders: characterization with quantitative MR imaging

Thirty patients with various hematologic disorders and 15 healthy control subjects underwent quantitative magnetic resonance (MR) imaging of the lumbar spine with spin-echo techniques. Images of patients with infiltrative bone marrow disorders showed significantly more prolonged T1 times than those of control subjects (P less than .001). It was not possible to distinguish different diffuse infiltrative bone marrow disorders on the basis of T1 values. Aplastic anemia could be distinguished from normality because of significantly shortened T1 (P less than .001). A significant correlation was seen between T1 and bone marrow cellularity (r = .74, P less than .001). T2 was of no value in the characterization of bone marrow disorders. Quantitative MR imaging dose not improve the diagnostic potential of bone marrow imaging in the detection of diffuse marrow infiltrates.