The combined effects of binder addition and different sintering methods on the mechanical properties of bovine hydroxyapatite

Hydroxyapatite (HA) from bovine bones has been used as a biomaterial in dentistry due to its biocompatibility and bioactivity. However, dense HA bioceramics still present inadequate properties for applications that require high mechanical performance, such as infrastructure. Microstructural reinforcements and control of ceramic processing steps are methods to improve these shortcomings. The present study assessed the effects of polyvinyl butyral (PVB) addition in combination with two sintering methodologies (2-step and conventional), on the mechanical properties of polycrystalline bovine HA bioceramics. The samples were divided into four groups (with 15 samples per group): conventional sintering with binder (HBC) and without binder (HWC) and 2-step sintering with (HB2) and without binder (HW2). HA was extracted from bovine bones, turned into nanoparticles in a ball mill, and subjected to uniaxial and isostatic pressing into discs, according to ISO 6872 standards. All groups were characterized by x-ray diffractometry (XRD), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and relative density. Besides, mechanical analyses (biaxial flexural strength (BFS) and modulus of elasticity) were also performed. The characterization results demonstrated that adding agglutinants or the sintering method did not affect HA's chemical and structural characteristics. Even so, the HWC group showed the highest mechanical values for BFS and modulus of elasticity being 109.0 (98.0; 117.0) MPa and 105.17 ± 14.65 GPa, respectively. The HA ceramics submitted to conventional sintering and without the addition of binders achieved better mechanical properties than the other groups. The impacts of each variable were discussed and correlated to the final microstructures and mechanical properties.

Sepsis: evolving concepts and challenges

Sepsis remains a major cause of morbidity and mortality worldwide, with increased burden in low- and middle-resource settings. The role of the inflammatory response in the pathogenesis of the syndrome has supported the modern concept of sepsis. Nevertheless, a definition of sepsis and the criteria for its recognition is a continuous process, which reflects the growing knowledge of its mechanisms and the success and failure of diagnostic and therapeutic interventions. Here we review the evolving concepts of sepsis, from the "systemic inflammatory response syndrome triggered by infection" (Sepsis-1) to "a severe, potentially fatal, organic dysfunction caused by an inadequate or dysregulated host response to infection" (Sepsis-3). We focused in the pathophysiology behind the concept and the criteria for recognition and diagnosis of sepsis. A major challenge in evaluating the host response in sepsis is to characterize what is protective and what is harmful, and we discuss that, at least in part, the apparent dysregulated host response may be an effort to adapt to a hostile environment. The new criteria for recognition and diagnosis of sepsis were derived from robust databases, restricted, however, to developed countries. Since then, the criteria have been supported in different clinical settings and in different economic and epidemiological contexts, but still raise discussion regarding their use for the identification versus the prognostication of the septic patient. Clinicians should not be restricted to definition criteria when evaluating patients with infection and should wisely use the broad array of information obtained by rigorous clinical observation.

B-cell subsets imbalance and reduced expression of CD40 in ataxia-telangiectasia patients

BACKGROUND

Ataxia-telangiectasia (AT) is a well-known primary immunodeficiency with recurrent sinopulmonary infections and variable abnormalities in both the humoral and cellular immune system. Dysfunctions in immunoglobulin production, reduced number of B cells, and B-cell receptor excision circles copies have been reported. We aimed to understand the immunological mechanisms involving the humoral compartment in AT patients by analysing peripheral blood B cells subsets, B-T lymphocyte cooperation through the expression of CD40 and CD40 ligand (CD40L), and cytokines involved in class-switch recombination production.

METHODS

We compared the proportion of B-cell subsets, the expression of CD40/CD40L, and the plasma levels of IL-6 and IFN-γ of 18 AT patients and 15 healthy age-sex-matched controls using flow cytometry.

RESULTS

We found that some steps in peripheral B cell development were altered in AT with a pronounced reduction of cell-surface CD40 expression. The proportions of transitional and naïve-mature B cells were reduced, whereas CD21-low, natural effector memory, IgM-only memory, and IgG atypical memory B cells were present in a higher proportion.

CONCLUSIONS

These findings revealed a disturbed B-cell homeostasis with unconventional maturation of B lymphocyte memory cells, which can explain the consequent impairment of humoral immunity.

Increased neutrophil oxidative burst metabolism in systemic lupus erythematosus

INTRODUCTION

There is increased frequency of discoid lesions (2.7%) and SLE (0.5%) in patients with chronic granulomatosus disease, but the literature is still controversial about phagocyte oxidative burst in SLE patients.

MATERIALS AND METHODS

300 SLE patients and 301 blood donors were evaluated for quantitation of the oxidative burst in phagocytes by flow cytometry based on the oxidation of 2,7-dichlorofluorescein-diacetate after stimuli with Staphylococcus aureus and Pseudomonas aeruginosa.

RESULTS

Neutrophils from SLE patients displayed higher basal reactive oxygen species (ROS) production than healthy controls [Mean of fluorescence intensity (MFI) = 53.77 ± 11.38 vs 15.08 ± 2.63, p < 0.001] and after stimulation with S. aureus (MFI = 355.46 ± 58.55 vs 151.92 ± 28.25, p < 0.001) or P. aeruginosa (MFI = 82.53 ± 10.1 vs 48.99 ± 6.74, p < 0.001). There was stronger neutrophil response after bacterial stimuli (ΔMFI) in SLE patients than in healthy controls (S. aureus = 301.69 ± 54.42 vs 118.38 ± 26.03, p < 0.001; P. aeruginosa = 28.76 ± 12.3 vs 15.45 ± 5.15, p < 0.001), but no difference with respect to the oxidative burst profile according to disease activity (SLEDAI ≥ 6) or severity (SLICC-DI ≥2). Patients with kidney involvement presented higher basal and stimulated ROS production in neutrophils.

DISCUSSION

The present findings corroborate the important role of innate immunity in SLE and implicate neutrophils in the pathophysiology of the disease.

Human monocytes tolerant to LPS retain the ability to phagocytose bacteria and generate reactive oxygen species

Tolerance to lipopolysaccharide (LPS) occurs when animals or cells exposed to LPS become hyporesponsive to a subsequent challenge with LPS. This mechanism is believed to be involved in the down-regulation of cellular responses observed in septic patients. The aim of this investigation was to evaluate LPS-induced monocyte tolerance of healthy volunteers using whole blood. The detection of intracellular IL-6, bacterial phagocytosis and reactive oxygen species (ROS) was determined by flow cytometry, using anti-IL-6-PE, heat-killed Staphylococcus aureus stained with propidium iodide and 2',7'-dichlorofluorescein diacetate, respectively. Monocytes were gated in whole blood by combining FSC and SSC parameters and CD14-positive staining. The exposure to increasing LPS concentrations resulted in lower intracellular concentration of IL-6 in monocytes after challenge. A similar effect was observed with challenge with MALP-2 (a Toll-like receptor (TLR)2/6 agonist) and killed Pseudomonas aeruginosa and S. aureus, but not with flagellin (a TLR5 agonist). LPS conditioning with 15 ng/mL resulted in a 40% reduction of IL-6 in monocytes. In contrast, phagocytosis of P. aeruginosa and S. aureus and induced ROS generation were preserved or increased in tolerant cells. The phenomenon of tolerance involves a complex regulation in which the production of IL-6 was diminished, whereas the bacterial phagocytosis and production of ROS was preserved. Decreased production of proinflammatory cytokines and preserved or increased production of ROS may be an adaptation to control the deleterious effects of inflammation while preserving antimicrobial activity.

Lipopolysaccharide-induced expression of cell surface receptors and cell activation of neutrophils and monocytes in whole human blood

Lipopolysaccharide (LPS) activates neutrophils and monocytes, inducing a wide array of biological activities. LPS rough (R) and smooth (S) forms signal through Toll-like receptor 4 (TLR4), but differ in their requirement for CD14. Since the R-form LPS can interact with TLR4 independent of CD14 and the differential expression of CD14 on neutrophils and monocytes, we used the S-form LPS from Salmonella abortus equi and the R-form LPS from Salmonella minnesota mutants to evaluate LPS-induced activation of human neutrophils and monocytes in whole blood from healthy volunteers. Expression of cell surface receptors and reactive oxygen species (ROS) and nitric oxide (NO) generation were measured by flow cytometry in whole blood monocytes and neutrophils. The oxidative burst was quantified by measuring the oxidation of 2',7'-dichlorofluorescein diacetate and the NO production was quantified by measuring the oxidation of 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate. A small increase of TLR4 expression by monocytes was observed after 6 h of LPS stimulation. Monocyte CD14 modulation by LPS was biphasic, with an initial 30% increase followed by a 40% decrease in expression after 6 h of incubation. Expression of CD11b was rapidly up-regulated, doubling after 5 min on monocytes, while down-regulation of CXCR2 was observed on neutrophils, reaching a 50% reduction after 6 h. LPS induced low production of ROS and NO. This study shows a complex LPS-induced cell surface receptor modulation on human monocytes and neutrophils, with up- and down-regulation depending on the receptor. R- and S-form LPS activate human neutrophils similarly, despite the low CD14 expression, if the stimulation occurs in whole blood.

Imbalance of naive and memory T lymphocytes with sustained high cellular activation during the first year of life from uninfected children born to HIV-1-infected mothers on HAART

The immune consequences of in utero HIV exposure to uninfected children whose mothers were submitted to highly active antiretroviral therapy (HAART) during gestation are not well defined. We evaluated 45 HIV-exposed uninfected (ENI) neonates and 45 healthy unexposed control (CT) neonates. All HIV-infected mothers received HAART during pregnancy, and the viral load at delivery was <50 copies/mL for 56.8%. Twenty-three ENI neonates were further evaluated after 12 months and compared to 23 unexposed healthy age-matched infants. Immunophenotyping was performed by flow cytometry in cord and peripheral blood. Cord blood lymphocyte numbers did not differ between groups. However, ENI neonates had a lower percentage of naive T cells than CT neonates (CD4+, 76.6 vs 83.1%, P < 0.001; CD8+, 70.9 vs 79.6%, P = 0.003) and higher percentages of central memory T cells than CT neonates (CD4+, 13.9 vs 8.7%, P < 0.001; CD8+, 8.6 vs 4.8%, P = 0.001). CD38 mean fluorescence intensity of T cells was higher in ENI neonates (CD4+, 62.2 vs 52.1, P = 0.007; CD8+, 47.7 vs 35.3, P < 0.001). At 12 months, ENI infants still had higher mean fluorescence intensity of CD38 on T cells (CD4+, 34.2 vs 23.3, P < 0.001; CD8+, 26.8 vs 19.4, P = 0.035). Despite effective maternal virologic control at delivery, HIV-exposed uninfected children were born with lower levels of naive T cells. Immune activation was present at birth and remained until at least 12 months of age, suggesting that in utero exposure to HIV causes subtle immune abnormalities.

Effect of pentoxifylline on lung inflammation and gas exchange in a sepsis-induced acute lung injury model

Experimental models of sepsis-induced pulmonary alterations are important for the study of pathogenesis and for potential intervention therapies. The objective of the present study was to characterize lung dysfunction (low PaO2 and high PaCO2, and increased cellular infiltration, protein extravasation, and malondialdehyde (MDA) production assessed in bronchoalveolar lavage) in a sepsis model consisting of intraperitoneal (ip) injection of Escherichia coli and the protective effects of pentoxifylline (PTX). Male Wistar rats (weighing between 270 and 350 g) were injected ip with 10(7) or 10(9) CFU/100 g body weight or saline and samples were collected 2, 6, 12, and 24 h later (N = 5 each group). PaO2, PaCO2 and pH were measured in blood, and cellular influx, protein extravasation and MDA concentration were measured in bronchoalveolar lavage. In a second set of experiments either PTX or saline was administered 1 h prior to E. coli ip injection (N = 5 each group) and the animals were observed for 6 h. Injection of 10(7) or 10(9) CFU/100 g body weight of E. coli induced acidosis, hypoxemia, and hypercapnia. An increased (P < 0.05) cell influx was observed in bronchoalveolar lavage, with a predominance of neutrophils. Total protein and MDA concentrations were also higher (P < 0.05) in the septic groups compared to control. A higher tumor necrosis factor-alpha (P < 0.05) concentration was also found in these animals. Changes in all parameters were more pronounced with the higher bacterial inoculum. PTX administered prior to sepsis reduced (P < 0.05) most functional alterations. These data show that an E. coli ip inoculum is a good model for the induction of lung dysfunction in sepsis, and suitable for studies of therapeutic interventions.

Leptospira interrogans activation of peripheral blood monocyte glycolipoprotein demonstrated in whole blood by the release of IL-6

Glycolipoprotein (GLP) from pathogenic serovars of Leptospira has been implicated in the pathogenesis of leptospirosis by its presence in tissues of experimental animals with leptospirosis, the inhibition of the Na,K-ATPase pump activity, and induced production of cytokines. The aims of the present study were to investigate the induction of IL-6 by GLP in peripheral blood mononuclear cells (PBMC) and to demonstrate monocyte stimulation at the cellular level in whole blood from healthy volunteers. PBMC were stimulated with increasing concentrations (5 to 2500 ng/ml) of GLP extracted from the pathogenic L. interrogans serovar Copenhageni, lipopolysaccharide (positive control) or medium (negative control), and supernatants were collected after 6, 20/24, and 48 h, and kept at -80 degrees C until use. Whole blood was diluted 1:1 in RPMI medium and cultivated for 6 h, with medium, GLP and lipopolysaccharide as described above. Monensin was added after the first hour of culture. Supernatant cytokine levels from PBMC were measured by ELISA and intracellular IL-6 was detected in monocytes in whole blood cultures by flow-cytometry. Monocytes were identified in whole blood on the basis of forward versus side scatter parameters and positive reactions with CD45 and CD14 antibodies. GLP ( > or = 50 ng/ml)-induced IL-6 levels in supernatants were detected after 6-h incubation, reaching a peak after 20/24 h. The percentage of monocytes staining for IL-6 increased with increasing GLP concentration. Thus, our findings show a GLP-induced cellular activation by demonstrating the ability of GLP to induce IL-6 and the occurrence of monocyte activation in whole blood at the cellular level.

Pentoxifylline decreases tumor necrosis factor and interleukin-1 during high tidal volume

Tumor necrosis factor-alpha (TNF-alpha) is one of the most important proinflammatory cytokines which plays a central role in host defense and in the acute inflammatory response related to tissue injury. The major source of TNF-alpha are immune cells such as neutrophils and macrophages. We tested the hypothesis that pentoxifylline, a methylxanthine derivative, down-regulates proinflammatory cytokine expression during acute lung injury in rats. Male Wistar rats weighing 250 to 450 g were anesthetized ip with 50 mg/kg sodium thiopental and randomly divided into three groups: group 1 (N = 7): tidal volume (V T) = 7 ml/kg, respiratory rate (RR) = 50 breaths/min and normal saline infusion; group 2 (N = 7): V T = 42 ml/kg, RR = 9 breaths/min and normal saline infusion; group 3 (N = 7): V T = 42 ml/kg, RR = 9 breaths/min and pentoxifylline infusion. The animals were ventilated with an inspired oxygen fraction of 1.0, a positive end-expiratory pressure of 3 cmH2O, and normal saline or pentoxifylline injected into the left femoral vein. The mRNA of TNF-alpha rapidly increased in the lung tissue within 180 min of ventilation with a higher V T with normal saline infusion. The concentrations of inflammatory mediators were decreased in plasma and bronchoalveolar lavage (BAL) in the presence of higher V T with pentoxifylline infusion (TNF-alpha: plasma, 102.2+/-90.9 and BAL, 118.2+/-82.1; IL-1 : plasma, 45.2+/-42.7 and BAL, 50.2+/-34.9, P < 0.05). We conclude that TNF-alpha produced by neutrophil influx may function as an alert signal in host defense to induce production of other inflammatory mediators.

Bloodstream infections in late-stage acquired immunodeficiency syndrome patients evaluated by a lysis centrifugation system

Opportunistic infections, which affect acquired immunodeficiency syndrome (Aids) patients, are frequently disseminated and may cause bloodstream infections (BSI). The aim of this study was to evaluate the main causes of BSI in Aids patients with advanced stage of the disease, with special emphasis on the identification of fungemia. During a 21 months period, all patients with Aids (CD4 < 200) and febrile syndrome admitted to 3 university hospitals were systematically evaluated. For each patient presenting fever, a pair of blood cultures was collected and processed by using a commercial lysis-centrifugation system. One hundred and eleven patients (75 males) with a mean age of 36 years (median 33 years) and mean CD4 count of 64 cells/ml were included. Among the 111 patients evaluated we documented 54 episodes of BSI, including 46 patients with truly systemic infections and 8 episodes considered as contaminants. BSI were caused by gram-positive bacteria (43%), fungi (20%), gram-negative bacteria (15%), mycobacteria (15%), and mixed flora (7%). The crude mortality rate of our patients was 39%, being 50% for patients with BSI and 31% for the others. In conclusion, BSI are a common related to systemic infections on Aids patients with advanced stage of disease and is associated with a high rate of mortality.

Immunophenotypic characterization of peripheral T lymphocytes in Mycobacterium tuberculosis infection and disease

The cellular immune response probably plays a pivotal role in determining the clinical outcome after exposure to Mycobacterium tuberculosis. We used multi-parameter flow-cytometry to evaluate the distribution of T-lymphocyte subsets during infection and disease caused by M. tuberculosis. Samples were obtained from 71 volunteers to identify the T CD4+ and CD8+ lymphocyte numbers, and the activation plus memory/naïve phenotypes, as defined by CD38, HLA-DR, CD45RA and CD27 markers. Subjects were divided into 18 healthy volunteers without detectable reaction to purified protein derivative (PPD-), 18 health care workers with a recent conversion to PPD, 20 patients with active pulmonary tuberculosis (TBC) and 15 patients with treated TBC at 6 months of therapy. By multiple-comparison analyses, the T CD4+ lymphocyte number of the TBC group was lower than the PPD- group (P < 0.05). This difference was apparently lost after treatment. The higher and the lower number of naïve T CD4+ cells was observed in the PPD- and TBC group, respectively. CD8+ T lymphocytes were also statistically different among the four groups (P = 0.0002), lower in the TBC group (P < 0.05). CD8+ T lymphocyte activation was evaluated by the CD38 and HLA-DR surface expression. The percentage distribution of these markers was statistically different between the four groups (P = 0.0055). TBC patients had a higher percentage of CD38+ cells and mean fluorescence index, suggesting an overall increase of cell activation. These results suggest that peripheral T lymphocytes reflect cellular activation during TBC, along with possible redistribution of naïve, memory/effector and late differentiated memory/effector phenotypes in the peripheral blood after infection and disease caused by M. tuberculosis.

Ventilation with high tidal volume induces inflammatory lung injury

Mechanical ventilation with high tidal volumes (V(T)) has been shown to induce lung injury. We examined the hypothesis that this procedure induces lung injury with inflammatory features. Anesthetized male Wistar rats were randomized into three groups: group 1 (N = 12): V(T) = 7 ml/kg, respiratory rate (RR) = 50 breaths/min; group 2 (N = 10): V(T) = 21 ml/kg, RR = 16 breaths/min; group 3 (N = 11): V(T) = 42 ml/kg, RR = 8 breaths/min. The animals were ventilated with fraction of inspired oxygen of 1 and positive end-expiratory pressure of 2 cmH2O. After 4 h of ventilation, group 3, compared to groups 1 and 2, had lower PaO2 [280 (range 73-458) vs 517 (range 307-596), and 547 mmHg (range 330-662), respectively, P<0.05], higher wet lung weight [3.62 +/- 0.91 vs 1.69 +/- 0.48 and 1.44 +/- 0.20 g, respectively, P<0.05], and higher wet lung weight/dry lung weight ratio [18.14 (range 11.55-26.31) vs 7.80 (range 4.79-12.18), and 6.34 (range 5.92-7.04), respectively, P<0.05]. Total cell and neutrophil counts were higher in group 3 compared to groups 1 and 2 (P<0.05), as were baseline TNF-alpha concentrations [134 (range <10-386) vs 16 (range <10-24), and 17 pg/ml (range <10-23), respectively, P<0.05]. Serum TNF-alpha concentrations reached a higher level in group 3, but without statistical significance. These results suggest that mechanical ventilation with high V T induces lung injury with inflammatory characteristics. This ventilatory strategy can affect the release of TNF-alpha in the lungs and can reach the systemic circulation, a finding that may have relevance for the development of a systemic inflammatory response.

Cytokines and pediatric open heart surgery with cardiopulmonary bypass

It is well known that, subsequent to cardiopulmonary bypass, and particularly in children, an inflammatory response within the body can often result in a characteristic syndrome. Recently, it has been suggested that this phenomenon is due to a systemic inflammatory response, with significant involvement of cytokines. With this in mind, we investigated the behavior of tumour necrosis factor-alpha and interleukin-6 during the operative and in the immediate postoperative period in a group of children submitted to open heart surgery. We investigated any possible relation between the levels of these cytokines in the serum and the length of cardiopulmonary bypass, with the serum levels of lactate, and with the extent of use of inotropic drugs in postoperative period. The cytokines were measured in samples withdrawn after induction of anesthesia, after 10 minutes of cardiopulmonary bypass, after re-establishment of circulation, and then 2 and 24 hours after the end of cardiopulmonary bypass. The levels of tumour necrosis factor-alpha and interleukin-6 increased between the beginning and at two hours of the end of cardiopulmonary bypass. There was no correlation between the levels of these cytokines in the serum and the length of cardiopulmonary bypass, although there was a positive relation between levels of interleukin-6 and lactate in samples withdrawn at two hours of the end of bypass, and the measured levels of the cytokines correlated with the extent of inotropic drugs employed in the postoperative period.

Production of IFN-gamma is impaired in patients with paracoccidioidomycosis during active disease and is restored after clinical remission

Cellular immunity is usually suppressed during paracoccidioidomycosis (PCM) and is restored after treatment. In this study we evaluated the induction of a type 1 (interferon gamma (IFN-gamma)), a type 2 (interleukin (IL)-10) and a primarily macrophage derived cytokine (tumor necrosis factor (TNF)-alpha) in peripheral blood mononuclear cells (PBMC) from patients with PCM. Eight male patients with active PCM, nine male patients with clinical remission of the disease and 10 healthy control subjects were enrolled in the study. Cytokines were induced with non-specific stimuli --phytohaemagglutin (PHA) (induces IL-10 and IFN-gamma), Lipopolysaccharide (induces TNF-alpha)--and Paracoccidioides brasiliensis antigen (PbAg) (induces IL-10, IFN-gamma and TNF-alpha). Induction of IFN-gamma with PHA differed among the three groups (P < 0.01; Kruskal-Wallis test) and with PbAg was lower in patients with active disease compared to those in clinical remission (P = 0.05; Mann-Whitney). Induction of IL-10 and of TNF-alpha was similar in the three groups. The suppressed production of IFN-gamma in patients with active disease may underscore the cellular immune deficiency seen in these patients.

Circulating levels of sTNFR and discrepancy between cytotoxicity and immunoreactivity of TNF-alpha in patients with visceral leishmaniasis

OBJECTIVES

To study the influence of soluble tumour necrosis factor (TNF) receptors (sTNFR) on bioactivity and immunoreactivity of TNF-alpha in patients with visceral leishmaniasis (Kala-azar) and to examine the association between circulating levels of sTNFR type I and type II with clinical manifestations of the disease.

METHODS

Ten patients with Kala-azar were enrolled. Plasma samples for TNF-alpha and sTNFR were obtained on days 0, 7 and 21-28 of antimonial therapy. Bioactivity of TNF-alpha was measured by cytotoxicity to L-929 cells and immunoreactivity by enzyme-linked immunosorbent assay (ELISA). sTNFR-I and sTNFR-II were measured by ELISA.

RESULTS

Measured by ELISA, TNF-alpha was detected at baseline in all patients (range from 22.3 to 163 pg/mL) and showed a linear decline over time on therapy (r = -0.49, P = 0.007). In contrast, when measured by cytotoxicity assay, TNF-alpha was detected in only one patient at baseline (193 pg/mL) and in four patients at the end of therapy (38.7, 95, 133 and 232 pg/mL) and there was no linear association between TNF-alpha and duration of therapy (r = -0.18, P = 0.45). sTNFR-I and sTNFR-II were detected in all patients before therapy. There was a strong positive correlation between plasma concentrations of sTNFR-I and sTNFR-II (r = 0.8, P = 0.006). Levels of sTNFR-I and sTNFR-II declined exponentially with time on therapy.

CONCLUSIONS

We concluded that sTNFR-I and sTNFR-II are related to disease activity in patients with Kala-azar and that these circulating receptors may interfere with the biological activity of TNF-alpha in patients with Kala-azar.

High rate of non-albicans candidemia in Brazilian tertiary care hospitals

In order to evaluate the epidemiology of candidemia in Brazil, we performed a prospective multicenter study conducted in six general hospitals from São Paulo and Rio de Janeiro, We enrolled a total of 145 candidemic patients (85 males) with a median age of 32 years. Non-albicans species accounted for 63% of all episodes and the species most frequently causing candidemia were C. albicans (37%), C. parapsilosis (25%), C. tropicalis (24%), C. rugosa (5%), and C. glabrata (4%). Systemic azoles were used before the onset of candidemia in only six patients. There were no differences in the coexisting exposures or underlying diseases associated with the species most frequently causing candidemia. The overall crude mortality rate was 50%. Nosocomial candidemias in our tertiary hospitals are caused predominantly by non-albicans species, which are rarely fluconazole resistant. This predominance of non-albicans species could not be related to the previous use of azoles.

Risk factors for death in patients with candidemia

OBJECTIVE

To analyze possible risk factors for death among patients with nosocomial candidemia. To identify risk factors for death in patients with candidemia, we analyzed demographic, clinical, and microbiological data.

SETTING

Six tertiary hospitals in Brazil.

PATIENTS

A cohort of 145 patients with candidemia.

DESIGN

26 possible risk factors for death, including age, underlying disease, signs of deep-seated infection, neutropenia, number of positive blood cultures, removal of a central venous catheter, etiologic agent of the candidemia, susceptibility pattern of the isolate to amphotericin B, and antifungal treatment were evaluated by univariate stepwise logistic regression analysis.

RESULTS

Non-albicans species accounted for 63.4% of the candidemias. Risk factors for death in univariate analysis were older age, catheter retention, poor performance status, candidemia due to species other than Candida parapsilosis, hypotension, candidemia due to species other than Candida parapsilosis, and no antifungal treatment. In multivariate analysis, older age and nonremoval of a central venous catheter were the only factors associated with an increased risk for death.

CONCLUSIONS

These data suggest that patients with candidemia and a central venous catheter should have the catheter removed.

Inflammatory response after myocardial revascularization with or without cardiopulmonary bypass

BACKGROUND

Tumor necrosis factor-alpha has been implicated in complications seen after cardiac operations with cardiopulmonary bypass. The release of tumor necrosis factor-alpha and its possible effects were studied in patients undergoing coronary artery bypass grafting with and without cardiopulmonary bypass.

METHODS

Twenty patients were studied, 10 with (group 1) and 10 without cardiopulmonary bypass (group 2). Serial blood samples were obtained before, during, and up to 48 hours after operation. Circulating tumor necrosis factor-alpha levels, leukocyte counts, and erythrocyte sedimentation rates were measured. Hemodynamic variables (blood pressure and heart rate), temperature, orotracheal intubation time, postoperative bleeding, and inotropic drug requirements were compared.

RESULTS

Serum levels of tumor necrosis factor-alpha were detected in 6 patients (60%) in group 1 and none in group 2. The patients in group 1 had more hypotension than those in group 2 (7.4 +/- 1.0 mm Hg versus 8.5 +/- 0.7 mm Hg), required more inotropic drugs (8 patients versus 1 patient), and had a higher heart rate (114 +/- 8 beats per minute versus 98 +/- 10 beats per minute), a higher temperature (37.1 degrees +/- 0.5 degrees C versus 36.6 degrees +/- 0.3 degrees C), increased postoperative bleeding (820 +/- 120 mL versus 360 +/- 84 mL), a longer orotracheal intubation time (13.6 +/- 2.2 hours versus 9.3 +/- 1.4 hours), and a more pronounced leukocytosis.

CONCLUSIONS

Cardiopulmonary bypass induces the whole-body inflammatory response through the release of tumor necrosis factor alpha, resulting in adverse systemic effects.

Presence of circulating levels of interferon-gamma, interleukin-10 and tumor necrosis factor-alpha in patients with visceral leishmaniasis

Experimental murine L. major infection is characterized by the expansion of distinct CD4+ T cell subsets. The Th1 response is related to production of IFN-gamma and resolution of infection, whereas Th-2 response with production of IL-4 and IL-10 and dissemination of infection. The objective of this study was to measure the circulating levels of IFN-gamma, IL-10 and TNF-alpha in patients with visceral leishmaniasis (VL) before, during and at the end of therapy and to examine the association between cytokine levels and activity of VL. Fifteen patients with VL were evaluated. The cytokine determinations were done by using the enzyme-linked immunoassay (ELISA) before, during and at the end of therapy. At baseline, we detected circulating levels of IFN-gamma in 13 of 15 patients (median = 60 pg/ml); IL-10 in 14 of 15 patients (median = 141.4 pg/ml); and TNF-alpha in 13 of 14 patients (median = 38.9 pg/ml). As patients improved, following antimonial therapy, circulating levels of IL-10 showed an exponential decay (y = 82.34 e-0, 10367x, r = -0.659; p < 0.001). IFN-gamma was no longer detected after 7/14 days of therapy. On the other hand, circulating levels of TNF-alpha had a less pronounced decay with time on therapy, remaining detectable in most patients during the first seven days of therapy (y = 36.99-0.933x, r = -0.31; p = 0.05). Part of the expression of a successful response to therapy may, therefore, include reduction in secretion of inflammatory as well as suppressive cytokines. Since IL-10 and IFN-gamma are both detected prior to therapy, the recognized cellular immune depression seen in these patients may be due to biological predominance of IL-10 (type 2 cytokine), rather than lack of IFN-gamma (type 1 cytokine) production.

Tumor necrosis factor alpha (TNF-alpha) and sepsis: evidence for a role in host defense

Serum levels of TNF-alpha were evaluated in 29 patients with sepsis, using TNF-alpha sensitive L929 cells (sensitivity = 15 pg/ml). Blood samples were collected serially at the first 24-36 h of symptoms. Seventeen patients had severe underlying disease and 12 patients had mild or no underlying disease. Shock was present in 25 patients. Overall mortality was 62.1%. TNF-alpha was detected in nine patients (range: 57.7-3,169 pg/ml). There was a tendency to detect TNF-alpha in patients with mild or no underlying disease (p = 0.07). Detection of TNF-alpha was associated with survival (p = 0.0003) even when adjusted for severity of underlying disease (p = 0.005), shock (p = 0.0005), coagulation abnormality (p = 0.002) and immunosuppressive therapy (p = 0.005), using a bivariate analysis. In this investigation, detection of circulating TNF-alpha was predictive of good outcome in septic patients, suggesting a role for this cytokine in host-defense against this kind of infection.

Plasma levels of tumor necrosis factor-alpha in patients with visceral leishmaniasis (Kala-azar). Association with activity of the disease and clinical remission following antimonial therapy

Evaluation of TNF-alpha in patients with Kala-azar has drawn increasing interest due to its regulatory role on the immune system, in addition to its cachetizing activity. The objective of this study was to examine the association between plasma levels of TNF-alpha, measured by immunoreactivity (ELISA) and bioactivity (cytotoxicity assay with L-929 cells), and clinical manifestations of visceral leishmaniasis. Plasma samples from 19 patients with Kala-azar were obtained before, during and at the end of antimonial therapy. TNF-alpha determinations was done by using the cytotoxicity assay (all patients) and the enzyme-linked immunoassay (ELISA-14 patients). A discrepancy between results obtained by ELISA and cytotoxicity assay was observed. Levels of circulating TNF-alpha, assessed by ELISA, were higher in patients than in healthy controls, and declined significantly with improvement in clinical and laboratory parameters. Plasma levels before treatment were 124.7 +/- 93.3 pg/ml (mean +/- SD) and were higher than at the end of therapy 13.9 +/- 25.1 pg/ml (mean +/- SD) (p = 0.001). In contrast, plasma levels of TNF-alpha evaluated by cytotoxicity assay did not follow a predicted course during follow-up. Lysis, in this case, might be not totally attributed to TNF-alpha. The discrepancy might be attributed to the presence of factor(s) known to influence the release and activity of TNF-alpha.

Nosocomial and community acquired bacteremia: variables associated with outcomes

Bacteremia is related to high morbidity and lethality. The present investigation was conducted to evaluate the variables associated with outcomes of bacteremia at a University Hospital in São Paulo, Brazil. Patients with bacteremia were identified through positive blood cultures performed at the microbiology laboratory between August 1985 and July 1986. Their charts were reviewed and the following variables were considered: age, sex, presence of underlying disease, where was the bacteremia acquired, source of infection, presence of shock and appropriateness of antimicrobial therapy. In the period of the study, there were 362 cases of bacteremia out of 16,636 admissions to the hospital. The lethality rate was 33.4%, six times higher than the mortality rate for non-bacteremic patients. Age greater than 40 years, presence of severe underlying disease, nosocomial acquisition, respiratory tract as the source of bacteremia, presence of shock and, being infected with Pseudomonas sp were significantly associated with fatal outcome. Appropriate antimicrobial therapy reduced the incidence of shock and improved survival of patients with bacteremia. This study provides information on outcome of patients with bacteremia at a University Hospital in Brazil and, settles the variables associated with poor outcome in these patients.

[Epidemiology of bacteremias at a university hospital]

The epidemiological aspects of bacteremias were determined in a university hospital, according to service, age, sex and place of acquisition (nosocomial or community-acquired). From August 1985 through July 1986 the incidence rate of bacteremias at the Sao Paulo Hospital was 21.7/1000 admissions. Such a high rate is probably related to the characteristics of the patients admitted to the hospital. The incidence was higher in the extremes of age and was similar in either sex. Approximately 60% of the bacteremias were nosocomial including 9.1% that were present at admission in patients transferred from other hospitals. The most frequent isolated pathogen was S. aureus. The most important source of bacteremia was the respiratory tract followed by the gastrointestinal and urinary tracts.

Squamous-cell carcinoma and lobomycosis (Jorge Lobo's disease)

Among the Cayabi Indians in Central Brazil, we found a high and unexpected prevalence of lobomycosis, which represents 21% of all the cases reported in the world medical literature until now. Most of the Cayabi patients have been observed for many years, and recently two developed cauliflower-like tumours in old lobomycosis scar lesions. The diagnosis of squamous cell carcinoma was confirmed histologically. In both cases, the tumor was surgically removed, but several months later tumors recurred in both patients. The appearance of squamous cell carcinoma in chronic scar lesions and ulcers of various etiologies has been reported by many authors, and should include lobomycosis.