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.     

Latent tuberculosis infection among undergraduate medical students in Rio de Janeiro State, Brazil.

SETTING: Five medical schools in three cities with different tuberculosis (TB) incidence rates in Rio de Janeiro State, Brazil. OBJECTIVE: To estimate prevalence of and associated factors for latent tuberculosis infection (LTBI) among medical students. DESIGN: A cross-sectional survey was conducted among undergraduate students in pre-clinical, early and late clinical years from schools in cities with low (28/100,000), intermediate (63/100,000) and high (114/100,000) TB incidence rates. Information on socio-demographic profile, previous BCG vaccination, potential TB exposure, co-morbidity and use of respiratory protective masks was obtained. A tuberculin skin test (TST) was performed using the Mantoux technique by an experienced professional. A positive TST, defined as induration > or = 10 mm, was considered LTBI. RESULTS: LTBI prevalence was 6.9% (95%CI 5.4-8.6). In multivariate analysis, male sex (adjusted odds ratio [aOR] 1.8; 95% CI 1.1-3.0), late clinical years (aOR 1.9; 95% CI 1.01-3.5), intermediate TB incidence (aOR 4.3; 95% CI 1.3-14.6) and high TB incidence in the city of medical school (aOR 5.1; 95% CI 1.6-16.8) were significantly associated with LTBI. CONCLUSIONS: The higher prevalence of LTBI in late clinical years suggests that medical students are at increased risk for nosocomial Mycobacterium tuberculosis infection. The implementation of a TB control program may be necessary in medical schools, particularly in cities with higher TB incidence.     

Randomized clinical trials and recent patterns in the use of statins

BACKGROUND: Three landmark trials involving 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) were published between 1994 and 1996 (the Scandinavian Simvastatin Survival Study [4S], the West of Scotland Coronary Prevention Study, and the Cholesterol and Recurrent Events trial). These trials provided evidence that lipid-lowering therapy decreases cardiovascular events, including mortality. Whether these recent data caused a shift toward statin use has not been evaluated. METHODS: Data from the National Ambulatory Medical Care Survey in 1980, 1981, 1985, and 1989 through 1998 were used. We analyzed 5053 visits by patients taking lipid-lowering medications to office-based physicians selected by stratified random sampling. The main outcome measure was use of specific lipid-lowering medications, including statins. RESULTS: In 1980 resins and niacin were the most commonly used lipid-lowering medications. By 1985 rising use of fibrates caused reductions in niacin use and resin use. By 1989 statins replaced fibrates as the most heavily used medications. Statin use climbed continuously thereafter, accounting for 90% of visits by patients treated for hypercholesterolemia in 1998. In time series analyses, increases in overall statin use were temporally unrelated to the publication of clinical trials, although the 4S trial may have contributed to a shift from older statins to simvastatin. For patients receiving lipid-lowering therapy in 1993 to 1998, statin use was significantly more likely for female patients, white patients, and patients visiting cardiologists. CONCLUSIONS: Although the market for lipid-lowering medications is dominated by statins, the rise in statins predated the recent clinical trials supporting their use.     

Human immunodeficiency virus-1 RNA levels and CD4 lymphocyte counts,during treatment for active tuberculosis,in South African patients

During 6 months of treatment, we measured human immunodeficiency virus (HIV)-1 virus loads, CD4 T cell counts, and immune activation markers, in 111 HIV-1-infected patients with active tuberculosis (TB). The median virus load (baseline, 5.58 log(10) copies/mL) significantly increased at 1 month (5.71 log(10) copies/mL), then returned to near-baseline levels at 3 months (5.40 log(10) copies/mL) and at 6 months (5.36 log(10) copies/mL). In contrast, the median CD4 counts increased at 1 month (186/mm(3)), at 3 months (238/mm(3)), and at 6 months (239/mm(3)). CD4 counts and virus loads did not change during therapy. Expression of CD38 and HLA-DR remained high throughout treatment, whereas plasma levels of interleukin-6 decreased over time.     

Mycobacterium avium complex in patients with HIV infection in the era of highly active antiretroviral therapy

Disseminated Mycobacterium avium complex (MAC) infection is a common complication of late-stage HIV-1 infection. Since the advent of highly active antiretroviral therapy (HAART), the rate of MAC infection has declined substantially, but patients with low CD4 cell counts remain at risk. Among patients in the Johns Hopkins cohort with advanced HIV disease, the proportion developing MAC has fallen from 16% before 1996 to 4% after 1996, with a current rate of less than 1% per year. Factors associated with developing MAC include younger age, no use of HAART, and enrollment before 1996. Prophylaxis with azithromycin or clarithromycin is recommended for all patients with CD4 counts less than 50 cells/mL. Optimum treatment for disseminated MAC includes clarithromycin and ethambutol, and another investigation suggests that the addition of rifabutin might reduce mortality. Both prophylaxis and treatment of disseminated MAC can be discontinued in patients who have responded to HAART, and specific guidelines for withdrawing treatment have been published. Although HAART has altered the frequency and outcome of MAC infection, it remains an important complication of AIDS.     

Serum beta 2-microglobulin decreases in patients with AIDS or ARC treated with azidothymidine

Abnormally elevated serum beta 2-microglobulin has been associated with progression of human immunodeficiency virus (HIV) disease and could reflect in vivo HIV activity. We prospectively studied the effect of azidothymidine therapy on serum beta 2-microglobulin concentration in 41 patients with AIDS or AIDS-related complex. Median beta 2-microglobulin concentration decreased from 4.02 mg/L before therapy to 3.73 mg/L at week 24 of therapy (P = .016). Individual changes in beta 2-microglobulin during azidothymidine therapy correlated with changes in serum HIV p24 antigen (Spearman, r = .42, P = .007). Also, in a randomized placebo-controlled study, median beta 2-microglobulin concentration decreased after 16 w of therapy in 5 azidothymidine-treated patients compared with levels in 7 placebo-treated controls (P = .05). Serum beta 2-microglobulin appears to be a sensitive marker for in vivo antiretroviral drug activity and may be a better marker than serum p24 antigen for early intervention trials involving antiretroviral agents.     

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.