Urban malaria in Dakar, Senegal: chemosusceptibility and genetic diversity of Plasmodium falciparum isolates

The chemosusceptibility and genetic polymorphism of Plasmodium falciparum populations from 48 patients hospitalized for malaria at the Hospital Principal in Dakar, Senegal were investigated during the 2002 malaria transmission season. Sixty-two percent of the isolates collected were from patients with severe malaria and 38% were from patients with mild malaria. In vitro activities of chloroquine, quinine, cycloguanil, atovaquone, mefloquine, halofantrine, and artesunate were evaluated. The prevalence of mutations in the Plasmodium falciparum dihydrofolate reductase (dhfr) and dihyropteroate synthetase (dhps) genes and the P. falciparum chloroquine resistance transporter (Pfcrt) gene associated with cycloguanil, pyrimethamine, sulfadoxine, and chloroquine resistance were estimated. The genetic polymorphism of the parasite populations was evaluated by analysis of the highly polymorphic regions of merozoite surface protein 1 (msp1) block 2 and msp2. Seventy percent of the isolates were assessed by an in vitro assay. Fifty-two percent of the isolates were chloroquine resistant, 45% were cycloguanil resistant, and 24% were atovaquone resistant. Four percent had low susceptibility to quinine. The Pfcrt and dhfr mutations were associated with in vitro chloroquine- and antimetabolic drug-resistant isolates, respectively. Approximately 70% of the isolates contained two or more clones. Genetic diversity of P. falciparum was high. The prevalence of allelic family K1 of msp1 was 68%. Isolates of P. falciparum were highly resistant to chloroquine, cycloguanil and atovaquone. The transmission rate of malaria in Dakar is low but a high degree of genetic polymorphism can increase severe malaria, as shown by persons coming to Dakar from areas highly endemic for malaria. Areas with urban malaria should use vector control measures and efficient chemoprophylaxis for non-immune populations.     

Growth arrest- and DNA-damage-inducible 45β gene inhibits c-Jun N-terminal kinase and extracellular signal-regulated kinase and decreases IL-1β-induced apoptosis in insulin-producing INS-1E cells

Aims/hypothesis IL-1β is a candidate mediator of apoptotic beta cell destruction, a process that leads to type 1 diabetes and progression of type 2 diabetes. IL-1β activates beta cell c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38, all of which are members of the mitogen-activated protein kinase (MAPK) family. Inhibition of JNK prevents IL-1β-mediated beta cell destruction. In mouse embryo fibroblasts and 3DO T cells, overexpression of the gene encoding growth arrest and DNA-damage-inducible 45β (Gadd45b) downregulates pro-apoptotic JNK signalling. The aim of this study was to investigate if Gadd45b prevents IL-1β-induced beta cell MAPK signalling and apoptosis.Materials Rat insulinoma INS-1E cells and mouse beta-TC3 cells stably expressing Gadd45b were generated. The effects of Gadd45b expression on signalling by JNK, ERK and p38 were assessed by Western blotting and kinase assays. Apoptosis rate was measured by terminal deoxynucleotidyl-mediated dUTP-biotin nick end-labelling (TUNEL) and an ELISA designed to detect apoptotic nucleosomes. Expression of endogenous Gadd45b mRNA was measured by RT-PCR.Results In INS-1E and beta-TC3 cells, expression of Gadd45b inhibited IL-1β-induced activation of JNK and ERK, but augmented IL-1β-mediated p38 activity. IL-1β-induced nitric oxide production and decreases in insulin content and secretion were reduced by GADD45β. IL-1β-induced apoptosis was reduced by GADD45β by up to 77%. Although IL-1β stimulated the time-dependent induction of endogenous Gadd45b in INS-1E cells and rat islets, expression levels were lower in these cells than in IL-1β-exposed NIH-3T3 and 3DO T cells.Conclusions/interpretation Inadequate induction of Gadd45b, which encodes a novel beta cell JNK and ERK inhibitor, may in part explain the pro-apoptotic response of beta cells to IL-1β.     

PAI-1 and TAFI in inflammatory bowel disease: the yin and yang of the fibrinolytic system

In both Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), an increased risk of thrombotic events has been demonstrated. Pathogenesis of thrombosis is multifactorial as various primary coagulation system abnormalities other than acquired factors have been reported. The fibrinolytic system has been widely investigated in IBD. Most of the available data report an imbalance in fibrinolytic capacity with a tendency toward a hypofibrinolytic state. Plasma thrombin-activatable fibrinolysis inhibitor and plasminogen activator inhibitor-1 are fundamental inhibitors of the fibrinolytic process and are also considered to be acute-phase reactants. Recent studies have shown an imbalance of plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor, suggesting that these molecules might contribute to thromboembolic events in both forms of IBD.     

Dispersion of repolarization and beta-thalassemia major: the prognostic role of QT and JT dispersion for identifying the high-risk patients for sudden death

Background: Patients with beta‐thalassemia major (β‐TM) are at increased risk for sudden cardiac death (SCD). Heterogeneity of ventricular repolarization is considered to provide an electrophysiological substrate for malignant arrhythmias. QT dispersion (QTc‐D) and JT dispersion (JTc‐D) are electrocardiographic parameters indicative of heterogeneity of ventricular repolarization. The aim of our study was to evaluate the heterogeneity of ventricular repolarization in patients with beta‐thalassemia and to test the hypothesis that an abnormal QTc and JTc dispersion may predict SCD in this population. Materials and Methods: The study involved 51 patients with β‐TM (age 33.9 ± 8.4; 33 M) and 51 healthy subjects used as controls, matched for age, gender, and body mass index (BMI). Among the β‐TM group, 14 patients with β‐TM (age 27 ± 6.64; 11 M) died from SCD during follow‐up. For each patient, QTD and JTD intervals were calculated. Results: Compared to the healthy control group, β‐TM group presented increased values of the QTc‐D (65.36 ± 33.95 vs. 37, 62 ± 17.65; P < 0.003) and JTc‐D (74.64 ± 33.27 vs. 40.32 ± 12.45; P < 0.001). In the β‐TM sudden death group, QTc‐D and JTc‐D were significantly greater than in survived β‐TM group (92.70 ± 44.24 vs. 56.14 ± 23.80, P = 0.0001; 101.54 ± 47.93 vs. 64.47 ± 17.90, P = 0.0001). A cutoff value of 70 ms for QTc‐D had a sensitivity and specificity of 77% in identifying patients at risk for SCD. A cutoff value of 100 ms for JTc‐D had a sensitivity of 65% and a specificity of 94% in identifying this category of patients. Conclusion: β‐TM is associated with significant changes in heterogeneity of ventricular repolarization. QTc and JTc dispersion are useful markers of risk of SCD in patients with β‐TM.     

Ticks parasitizing humans in Greece

In summer 2008, two fatal cases were observed in Northeastern Greece: a Crimean-Congo hemorrhagic fever (CCHF) case (first report in Greece) and a Mediterranean spotted fever case. In total, 537 ticks removed from humans who referred for this reason to the two hospitals of the region during June-September 2008 were identified. The vast majority of them (81.5%) were Rhipicephalus sanguineus, which is the main vector of Rickettsia conorii, while Hyalomma marginatum, the main vector of CCHF virus, accounted for 5.2%. The increased aggressiveness of R. sanguineus might be related to the weather conditions occurred during 2007-2008, while a variety of factors, including climate, might play a role in CCHF emergence.     

Mesenchymal cells recruit and regulate T regulatory cells

OBJECTIVE: Despite much investigation into T regulatory cells (Tregs), little is known about the mechanism controlling their recruitment and function. Because multipotent mesenchymal stromal cells (MSCs) exert an immune regulatory function and suppress T-cell proliferation, this in vitro study investigated their role in Treg recruitment and function. MATERIALS AND METHODS: Human MSCs and different T cell populations (CD3(+), CD3(+)/CD45RA(+), CD3(+)/CD45RO(+), CD4(+)/CD25(+), CD4(+)/CD25(+)/CD45RO(+), CD4(+)/CD25(+)/CD45RA(+)) from healthy donors were cocultured for up to 15 days. Harvested lymphocytes were analyzed by flow cytometry and FoxP3 and CD127 expressions were measured by real-time polymerase chain reaction. Their regulatory activity was assessed. RESULTS: We demonstrate MSC recruit Tregs from a fraction of CD3(+) and from immunoselected CD3(+)/CD45RA(+) and CD3(+)/CD45RO(+) fractions. After culture with MSCs both immunoselected fractions registered increases in the CD4(+)/CD25(bright)/FoxP3 subset and CD127 expression was downregulated. When purified Treg populations (CD4/CD25(+), CD4/CD25(+)/CD45RA(+), and CD4/CD25(+)/CD45RO(+)) are used in MSC cocultures, they maintain FoxP3 expression and CD127 expression is downregulated. Treg suppressive capacity was maintained in Treg populations that were layered on MSC for up to 15 days while control Tregs lost all suppressive activity after 5 days culture. CONCLUSIONS: In conclusion, our study demonstrates that MSCs recruit, regulate, and maintain T-regulatory phenotype and function over time.     

Circulating endothelial cells as a marker of ongoing vascular disease in systemic sclerosis

OBJECTIVE: Circulating endothelial cells (CECs) have been described in different conditions involving vascular injury. Vascular abnormalities play a key role in the pathogenesis of systemic sclerosis (SSc). The aim of this study was to search for the presence of CECs in patients with SSc and to evaluate their clinical associations and possible pathogenic role. METHODS: The study cohort included 46 patients with SSc and 40 healthy controls. Five-parameter, 3-color flow cytometry was performed with a FACScan. CECs were defined as CD45 negative, CD34 positive, and P1H12 positive, and activated CECs were defined as CD45 negative and P1H12 positive, CD62 positive, or CD106 positive. Progenitors were identified as CD34 positive and CD133 positive. RESULTS: Total and activated CEC counts were significantly higher in SSc patients compared with healthy controls and were positively correlated with the disease activity score. With respect to visceral involvement, significant correlation was observed between the CEC number and the severity of pulmonary hypertension. High levels of endothelial progenitors were observed in patients with SSc, and the counts were higher in the early stages of disease. CONCLUSION: The presence of CECs in patients with SSc may represent direct evidence of endothelial disease and may be a promising new clinical marker for active SSc. Notably, the association between CECs and pulmonary hypertension and impaired carbon monoxide diffusing capacity was evident in patients with limited cutaneous SSc only, suggesting an important role for CECs in this disease subset with prominent vascular changes. Detection of circulating endothelial progenitors may represent a response to vascular ischemia in early SSc, as an attempt at revascularization.     

Long-term efficacy and tolerance of efavirenz- and nevirapine-containing regimens in adult HIV type 1 Senegalese patients

Owing to their low toxicity, low price, and ease of use, efavirenz (EFV) and nevirapine (NVP) are frequently used as part of antiretroviral regimens for AIDS treatment. Several clinical trials have already studied their efficacy and tolerance. However, long-term observations of the effects of these drugs in patients are limited. We used data from a prospective Senegalese cohort to analyze long-term tolerance and efficacy of these two drugs in a low-resources setting. Patients were included if they started their therapy with EFV or NVP. They were censored after treatment discontinuation. The primary endpoint was the time to treatment discontinuation. Secondary endpoints included time to death, time to disease progression, occurrence of severe adverse effects, CD4 cell recovery, and virological response. Confounding factors were controlled using marginal structural models. The median follow-up time in both EFV and NVP arms was 48 months. The hazard ratio (HR) of drug discontinuation in the EFV arm vs. the NVP arm was 0.84 (0.34; 1.87). There was a borderline difference in virological response [HR 1.38 (0.999; 1.89)] but no differences in time to death [HR 1.15 (0.41; 3.24)], time to AIDS progression [HR 1.25 (0.61; 2.58)], or time to increase in CD4 cell count above 500 cells/mm3. Adverse effects were different between NVP and EFV, but long-term tolerance was good for both. This analysis provided further information on long-term tolerance and efficacy of EFV and NVP in a resource-limited setting.     

Rectal cell proliferation and colon cancer risk in patients with hypergastrinaemia

Background—The influence of gastrin on the colonicmucosa is still uncertain. Some authors have suggested a stimulatingeffect on the growth of normal and malignant colonic epithelium, while others have shown no association between gastrin and neoplastic development.
Aims—To evaluate the effect of gastrin oncolorectal cell proliferation, patients with chronic endogenoushypergastrinaemia underwent proctoscopy. Biopsy specimens were taken inorder to study rectal cell kinetics.
Patients and controls—Ten patients with chronicautoimmune gastritis (CAG), six patients with Zollinger-Ellisonsyndrome (ZES), and 16 hospital controls took part in this study.Patients with CAG and ZES had basal serum gastrin concentrationssignificantly higher than controls (p<0.001).
Methods—Immunohistochemistry was performed on 3 µm sections of rectal biopsy specimens incubated with5'-bromodeoxyuridine.
Results—The percentage of proliferating cells inthe entire crypts (overall labelling index) was similar in all thegroups. However, the labelling frequency in the upper two fifths of the glands (ϕh value) was significantly higher in patients with CAG orZES compared with controls (p<0.01 in both patient groups versus controls).
Conclusions—Endogenous hypergastrinaemia isassociated with rectal cell proliferation defects, similar to thoseobserved in conditions at high risk for colon cancer. The effect of theincreased serum concentrations of gastrin on the colorectal mucosaafter treatment with drugs inhibiting gastric acid secretion should be investigated.

     

NOTCH and NF-κB interplay in chronic lymphocytic leukemia is independent of genetic lesion

The NOTCH and nuclear factor kappa B (NF-κB) pathways are both constitutively activated in Chronic Lymphocytic Leukemia (CLL). We first described the NOTCH1 PEST domain mutation in a CLL subgroup, but the activation of the NOTCH pathway in NOTCH1-unmutated cases remains unexplained. Here, we investigated whether genetic lesions in the NF-κB/NOTCH loop might support the NOTCH activation status by sequencing negative (TNFAIP3/A20) and positive (TRAF2, TRAF5, TNFRSF11A/RANK, MAP3K7/TAK1, and CARD11) regulators of NF-κB together with NF-κB targets on the NOTCH pathway, the NOTCH ligands Jagged1 and Jagged2, in CLL patients. The sequence analysis revealed four missense mutations for A20, TRAF2, TRAF5 and RANK1 genes, all causing a change in amino acid group from polar to non-polar, but functional domains were not involved. Specific predictive software analyses confirmed that the amino acid changes have a low-functional impact on the protein. Our results show that in CLL, NF-κB regulators and Jagged are both unmutated, suggesting that the Jagged-mediated interplay between NF-κB and NOTCH is independent of genetic lesions.