Plasmodium falciparum histidine-rich protein II binds to actin,phosphatidylinositol 4,5-bisphosphate and erythrocyte ghosts in a pH-dependent manner and undergoes coil-to-helix transitions in anionic micelles

The recombinant histidine-rich protein II (HRPII) from Plasmodium falciparum was shown to bind actin and phosphatidylinositol 4,5-bisphosphate (PIP(2)) in vitro in a pH-dependent manner, very similar to hisactophilin, an actin-binding protein from ameba. Binding of HRPII to actin and PIP(2) occurred at pH 6.0 and 6.5, but not above pH 7.0. Circular dichroism (CD) spectroscopy confirmed that HRPII interacts with actin at pH below 7.0, as judged by the changes induced in the secondary structure of the HRPII/actin mixture. Further CD analysis demonstrated that HRPII adopts a predominantly alpha-helical conformation with anionic micelles of PIP(2) and SDS, but not with neutral micelles of phosphatidylcholine (PC), a feature that is common to many actin-binding proteins involved in cytoskeleton remodeling. Similarly to hisactophilin, a GFP-HRPII fusion protein shuttled from the cytoplasm to the nucleus of HeLa cells as the cellular pH was lowered from 8.0 to 6.0. HeLa cells transfected with the HRPII gene showed increased levels of histidine-rich proteins (HRPs) in the soluble cell fraction at pH 8.0. At pH 6.0, however, HRPs were detected mainly in the insoluble cell fraction. Interestingly, we found that HRPII binds to human erythrocyte membranes at pH 6.0 and 6.5 but not at pH above 7.0. Our results point to remarkable similarities between HRPII, hisactophilin, and actin-binding proteins. Possible roles of the HRPII during Plasmodium infection are discussed in the light of these findings.     

Sputum cytokine levels in patients with pulmonary tuberculosis as early markers of mycobacterial clearance

Sputum and serum from patients with active pulmonary tuberculosis (TB), healthy purified protein derivative-positive adults, and patients with bacterial pneumonia were collected to simultaneously assess local immunity in the lungs and peripheral blood. To determine whether cytokine profiles in sputum from TB patients and control subjects were a reflection of its cellular composition, cytospin slides were prepared in parallel and assessed for the presence of relative proportions of epithelial cells, neutrophils, macrophages, and T cells. Gamma interferon (IFN-gamma) in sputum from TB patients was markedly elevated over levels for both control groups. With anti-TB therapy, IFN-gamma levels in sputum from TB patients decreased rapidly and by week 4 of treatment were comparable to those in sputum from controls. Further, IFN-gamma levels in sputum closely followed mycobacterial clearance. Although detected at fourfold-lower levels, IFN-gamma immunoreactivities in serum followed kinetics in sputum. TNF-alpha, interleukin 8 (IL-8) and IL-6 also were readily detected in sputum from TB patients at baseline and responded to anti-TB therapy. In contrast to IFN-gamma, however, TNF-alpha and IL-8 levels also were elevated in sputum from pneumonia controls. These data indicate that sputum cytokines correlate with disease activity during active TB of the lung and may serve as potential early markers for sputum conversion and response to anti-TB therapy.     

Delayed onset of lactation and risk of ending full breast-feeding early in rural Guatemala

Mothers of infants (n = 328) born between 1996 and 1999 in four Guatemalan communities were interviewed every 2 wk until 6 mo postpartum (pp) to collect prospective breast-feeding data and assess the association between delayed (>3 d pp) onset of lactation (OL) and the risk of ending full breast-feeding. Cox proportional hazards regression was used to examine the association between delayed OL and the hazard of ending full breast-feeding in the first 6 mo, adjusted for potential confounders and effect modifiers. A significant interaction with community was found (community-specific hazard ratios: HR(A) = 2.87, 95% CI = 1.25, 6.60; HR(B) = 3.43, 95% CI = 1.55, 7.59; HR(C) = 0.26, 95% CI = 0.06, 1.14; HR(D) = 1.11, 95% CI = 0.44, 2.77). Supplementation before OL (preonset supplementation) was associated with delayed OL [odds ratio (OR) = 4.87, 95% CI = 2.29, 10.36] and an increased risk of ending full breast-feeding (HR = 1.49, 95% CI = 1.05, 2.11). In the two communities in which mothers who experienced delayed OL had a significantly greater risk of ending full breast-feeding than did mothers experiencing normal OL, the association between delayed OL and full breast-feeding was mediated in part by preonset supplementation. Further analyses suggest that this was due to delayed OL leading to nonbreast milk feeds, rather than to introduction of supplements delaying OL. We conclude that some mothers who experience delayed OL are less likely to continue full breast-feeding in the first 6 mo and that further research should examine the contextual factors that modify this relationship.     

Changes in homologous and heterologous gap junction contacts during maturation-inducing hormone-dependent meiotic resumption in ovarian follicles of Atlantic croaker

Homologous (granulosa cell-granulosa cell) gap junction (GJ) contacts increase in ovarian follicles of Atlantic croaker (Micropogonias undulatus) during the early (first) stage of maturation, but their profile during the second stage [i.e., during maturation-inducing hormone (MIH)-mediated meiotic resumption] is unknown. The profile of homologous GJ contacts during the second stage of maturation in croaker follicles was examined in this study and compared to that of heterologous (granulosa cell-oocyte) GJ, for which changes have been previously documented. Follicles were incubated with human chorionic gonadotropin to induce maturational competence (first stage), and then with MIH to induce meiotic resumption. The follicles were collected for examination immediately before and after different durations of MIH exposure until the oocyte had reached the stage of germinal vesicle breakdown (GVBD; index of meiotic resumption). Ultrathin sections were observed by transmission electron microscopy, and homologous and heterologous GJ contacts were quantified along a 100-microm segment of granulosa cell-zona radiata complex per follicle (three follicles/time/fish, n=3 fish). Relatively high numbers of both types of GJ were observed before and after the first few hours of MIH exposure (up to the stage of oil droplet coalescence). GJ numbers declined during partial yolk globule coalescence (at or near GVBD) and were just under 50% of starting values after the completion of GVBD (P<0.05). These results confirm earlier observations that GVBD temporally correlates with declining heterologous GJ contacts, and for the first time in teleosts show that there is a parallel decline in homologous GJ. The significance of the changes in homologous and heterologous GJ is uncertain and deserves further study.     

Preoperative risk stratification in infective endocarditis. Does the EuroSCORE model work? Preliminary results.

OBJECTIVE: There is an important role for risk prediction in cardiac surgery. Prediction models are useful in decision making and quality assurance. Patients with infective endocarditis (IE) have a particularly high risk of mortality. The aim was to assess the performance of European System for Cardiac Operative Risk Evaluation (EuroSCORE) in IE. METHODS: The additive and logistic EuroSCORE models were applied to all patients undergoing surgery for IE (Duke criteria) between January 1995 and April 2006 within our prospective institutional database. Observed and predicted mortalities were compared. Model calibration was assessed with the Hosmer-Lemeshow test. Model discrimination was tested by determining the area under the receiver operating characteristic (ROC) curve. RESULTS: One hundred and eighty-one consecutive patients undergoing 191 operations were analyzed. Observed mortality was 28.8%. For the entire cohort the mean additive score was 10.4 (additive predicted mortality of 14.2%). The mean logistic predicted mortality was 27.1%. Discriminative power was good for the additive and the logistic models for the entire series. Area under ROC curve were 0.83 (additive) and 0.84 (logistic) for the entire cohort, 0.81 and 0.81 for the aortic position, 0.91 and 0.92 for the mitral position, 0.81 and 0.81 for the native valve, 0.82 and 0.83 for the prosthetic valves, and 0.81 and 0.51 for the gram-positive microorganisms, respectively. CONCLUSIONS: This initial sample may be small; however, additive and logistic EuroSCORE adequately stratify risk in IE. Logistic EuroSCORE has been calibrated in IE, a special group of very high-risk patients. Further studies with larger sample sizes are required to confirm these initial results.     

Retrospective assessment of potential interaction between levofloxacin and warfarin

Objective There is currently a controversy regarding interactions between levofloxacin and warfarin. The aim of this study was to determine the clinical relevance of this interaction in our setting. Setting A university hospital in Barcelona, Spain. Methods We carried out a retrospective evaluation of all patients hospitalized in our hospital during the period 2000–2005, selecting all those concomitantly treated with levofloxacin and warfarin for the study. The following data were compiled: demographic information, concomitant medication, comorbid conditions, and relevant analytical parameters, particularly the international normalized ratio (INR), including values taken before, during, and after concomitant administration of the two study drugs. Patients for whom INR values during concomitant administration were not available were excluded. Differences in INR before and during the potential interaction, and before and after the interaction were analyzed with the Wilcoxon t test using SPSS (V12.0). In addition, patients were stratified according to presence or not of toxic habits (smoking/alcohol consumption) to investigate the possible impact of these factors on the interaction under study. Results Among the 30 patients identified, 9 were excluded because INR data during concomitant administration of warfarin and levofloxacin were not available. Statistical analysis demonstrated significant increase in INR (P = 0.001) following addition of levofloxacin to warfarin therapy. Conclusions. The results of this study reaffirm the hypothesis that concomitant administration of levofloxacin and warfarin leads to INR increase; hence close monitoring of INR is advisable when patients are prescribed this combination of drugs. This paper has not been submitted elsewhere in similar form, and all authors have contributed significantly to the publication. All authors are aware of the submission and agree with it.     

Evaluation of oral antiseptic rinsing before sputum collection to reduce contamination of mycobacterial cultures

To assess whether rinsing with oral antiseptics before sputum collection would reduce contamination of mycobacterial cultures, 120 patients with suspected tuberculosis were randomly assigned to rinse with chlorhexidine or cetylpyridinium mouthwash before collection. The culture contamination rate was significantly lower after rinsing with chlorhexidine before collection, especially for cultures grown in MGIT medium.