Plasmodium falciparum Adhesion on Human Brain Microvascular Endothelial Cells Involves Transmigration-Like Cup Formation and Induces Opening of Intercellular Junctions

Cerebral malaria, a major cause of death during malaria infection, is characterised by the sequestration of infected red blood cells (IRBC) in brain microvessels. Most of the molecules implicated in the adhesion of IRBC on endothelial cells (EC) are already described; however, the structure of the IRBC/EC junction and the impact of this adhesion on the EC are poorly understood. We analysed this interaction using human brain microvascular EC monolayers co-cultured with IRBC. Our study demonstrates the transfer of material from the IRBC to the brain EC plasma membrane in a trogocytosis-like process, followed by a TNF-enhanced IRBC engulfing process. Upon IRBC/EC binding, parasite antigens are transferred to early endosomes in the EC, in a cytoskeleton-dependent process. This is associated with the opening of the intercellular junctions. The transfer of IRBC antigens can thus transform EC into a target for the immune response and contribute to the profound EC alterations, including peri-vascular oedema, associated with cerebral malaria.     

Proteomics of life at low temperatures: trigger factor is the primary chaperone in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

The proteomes expressed at 4°C and 18°C by the psychrophilic Antarctic bacterium Pseudoalteromonas haloplanktis have been compared using two‐dimensional differential in‐gel electrophoresis, showing that translation, protein folding, membrane integrity and anti‐oxidant activities are upregulated at 4°C. This proteomic analysis revealed that the trigger factor is the main upregulated protein at low temperature. The trigger factor is the first molecular chaperone interacting with virtually all newly synthesized polypeptides on the ribosome and also possesses a peptidyl‐prolyl cis‐trans isomerase activity. This suggests that protein folding at low temperatures is a rate‐limiting step for bacterial growth in cold environments. It is proposed that the psychrophilic trigger factor rescues the chaperone function as both DnaK and GroEL (the major bacterial chaperones but also heat‐shock proteins) are downregulated at 4°C. The recombinant psychrophilic trigger factor is a monomer that displays unusually low conformational stability with a Tm value of 33°C, suggesting that the essential chaperone function requires considerable flexibility and dynamics to compensate for the reduction of molecular motions at freezing temperatures. Its chaperone activity is strongly temperature‐dependent and requires near‐zero temperature to stably bind a model‐unfolded polypeptide.     

Design of new potent and selective secretory phospholipase A2 inhibitors. 6-Synthesis,structure–activity relationships and molecular modelling of 1-substituted-4-[4,5-dihydro-1,2,4-(4H)-oxadiazol-5-one-3-yl(methyl)]-functionalized aryl piperazin/one/dione derivatives

The group IIA human non-pancreatic secretory phospholipase A₂ (hnp-sPLA₂) is one of the enzymes implied in the inflammatory process. In the course of our work on inhibitors of this enzyme we investigated the influence of rigidity of the piperazine region on the biological activity. Several modifications were explored. Various linkers, such as amide, urea, carbamate, or alkoxyphenyl were inserted between the piperazine and the lipophilic chain. Also, modification of the piperazine core to incorporate carbonyl groups was studied. In an in vitro fluorimetric assay using the human GIIA (HPLA₂) and porcine pancreatic GIB enzymes, compound 60a (Y = phenoxy, R = C₁₈H₃₇, Z = CH₂) had the optimal activity with an IC₅₀ = 30 nM on HPLA₂. By means of molecular modelling we attempted to get informations towards comprehension of differences in activity.     

Phenotypic plasticity of body size in Drosophila: effects of a daily periodicity of growth temperature in two sibling species

Abstract. Variation of wing and thorax length under thermoperiodic growth conditions was analysed in four strains of two sibling species, Drosophila melanogaster and D. simulans , from two European localities. Results were compared to those obtained with constant temperatures ranging from 12 to 31 °C.
Under constant temperatures the data basically confirmed previous results: concave reaction norms for wing and thorax length; a monotonically decreasing norm for wing : thorax ratio; and an increasing norm for sex dimorphism (female : male ratio). Phenotypic variability was maximum at extreme temperatures and minimum at middle ones. Slight differences were observed according to the geographical origin: the difference between strains from Bordeaux (France) and Cordoba (Spain) was maximum at low temperatures but disappeared at about 28 °C.
According to the temperatures chosen, alternating thermal regimens had either no effect or produced a significant size reduction, probably reflecting a periodic stress. The magnitude of this effect was proportional to the amplitude of the thermoperiod but not to the quality (cold or heat) of the stress. In a similar way, the wing : thorax ratio was either not modified or reduced significantly, indicating that wing length was relatively more affected than thorax length by alternating thermal regimens. Sex dimorphism also showed either no change or a significant increase, indicating that males were relatively more reactive than females to alternating conditions. Finally, regimens of broad amplitudes increased the phenotypic variability, again an indication of stressful effects. All these observations should be taken into account when analysing phenotypic variability in nature and trying to understand natural selection in wild-living populations.     

Lipid Peroxidation and Total Cholesterol in HAART-Na?ve Patients Infected with Circulating Recombinant Forms of Human Immunodeficiency Virus Type-1 in Cameroon

Background

HIV infection has commonly been found to affect lipid profile and antioxidant defense.

Objectives

To determine the effects of Human Immunodeficiency Virus (HIV) infection and viral subtype on patient’s cholesterol and oxidative stress markers, and determine whether in the absence of Highly Active Antiretroviral Therapy (HAART), these biochemical parameters could be useful in patient’s management and monitoring disease progression in Cameroon. For this purpose, we measured total cholesterol (TC), LDL cholesterol (LDLC), HDL cholesterol (HDLC), total antioxidant ability (TAA), lipid peroxidation indices (LPI), and malondialdehyde (MDA) in HIV negative persons and HIV positive HAART-naïve patients infected with HIV-1 group M subtypes.

Methods

We measured serum TC, LDLC, HDLC, plasma MDA, and TAA concentrations, and calculated LPI indices in 151 HIV-positive HAART-naïve patients and 134 seronegative controls. We also performed gene sequence analysis on samples from 30 patients to determine the effect of viral genotypes on these biochemical parameters. We also determined the correlation between CD4 cell count and the above biochemical parameters.

Results

We obtained the following controls/patients values for TC (1.96±0.54/1. 12±0. 48 g/l), LDLC (0. 67±0. 46/0. 43±0. 36 g/l), HDLC (105. 51±28. 10/46. 54±23. 36 mg/dl) TAA (0. 63±0. 17/0. 16±0. 16 mM), MDA (0. 20±0. 07/0. 41±0. 10 µM) and LPI (0. 34±0. 14/26. 02±74. 40). In each case, the difference between the controls and patients was statistically significant (p<0.05). There was a positive and statistically significant Pearson correlation between CD4 cell count and HDLC (r = +0.272; p<0.01), TAA (r = +0.199; p<0.05) and a negative and statistically significant Pearson correlation between CD4 cell count and LPI (r = −0.166; p<0.05). Pearson correlation between CD4 cell count and TC, CD4cell count and LDLC was positive but not statistically significant while it was negative but not statistically significant with MDA. The different subtypes obtained after sequencing were CRF02_AG (43.3%), CRF01_AE (20%), A1 (23.3%), H (6.7%), and G (6.7%). None of the HIV-1 subtypes significantly influenced the levels of the biochemical parameters, but by grouping them as pure subtypes and circulating recombinant forms (CRFs), the CRF significantly influenced TC levels. TC was significantly lower in patients infected with CRF (0.87±0.27 g/l) compared to patients infected with pure HIV-1 subtypes (1.32±0.68 g/l) (p<0.017). MDA levels were also significantly higher in patients infected with HIV-1CRF01_AE (0.50±0.10 µM), compared to patients infected with CRF02_AG (0. 38±0. 08 µM) (p<0.018).

Conclusion

These results show that HIV infection in Cameroon is associated with significant decrease in TAA, LDLC, HDLC and TC, and increased MDA concentration and LPI indices which seem to be linked to the severity of HIV infection as assessed by CD4 cell count. The data suggests increased oxidative stress and lipid peroxidation in HIV-infected patients in Cameroon, and an influence of CRFs on TC and MDA levels.     

1H, 15N and 13C resonance assignments for the three LOTUS RNA binding domains of Tudor domain-containing protein TDRD7

The LOTUS or OST-HTH domain is a recently discovered motif of about 80 amino acids and is found in several germline-specific proteins including the Tudor domain-containing proteins TDRD5 and TDRD7, which are important for germ cell development. The LOTUS domain is an RNA binding domain but its exact function is unknown. Here, we report the ¹H, ¹³C and ¹⁵N resonance assignments for the three LOTUS domains present in mouse TDRD7. These assignments will allow three-dimensional structure determination of the LOTUS domains and mapping of their interaction with RNA, steps toward deciphering the function of TDRD7.     

CD8 T-Cells from Most HIV-Infected Patients Lack Ex Vivo HIV-Suppressive Capacity during Acute and Early Infection

The strong CD8+ T-cell-mediated HIV-1-suppressive capacity found in a minority of HIV-infected patients in chronic infection is associated with spontaneous control of viremia. However, it is still unclear whether such capacities were also present earlier in the CD8+ T cells from non controller patients and then lost as a consequence of uncontrolled viral replication. We studied 50 patients with primary HIV-1-infection to determine whether strong CD8+ T-cell-mediated HIV suppression is more often observed at that time. Despite high frequencies of polyfunctional HIV-specific CD8+ T-cells and a strong CD4+ T-helper response, CD8+ T-cells from 48 patients lacked strong HIV-suppressive capacities ex vivo. This indicates that the superior HIV-suppressive capacity of CD8+ T-cells from HIV controllers is not a general characteristic of the HIV-specific CD8+ T cell response in primary HIV infection.     

Laminin Receptor 37/67LR Regulates Adhesion and Proliferation of Normal Human Intestinal Epithelial Cells

Interactions between the cell basal membrane domain and the basement membrane are involved in several cell functions including proliferation, migration and differentiation. Intestinal epithelial cells can interact with laminin, a major intestinal basement membrane glycoprotein, via several cell-surface laminin-binding proteins including integrin and non-integrin receptors. The 37/67kDa laminin receptor (37/67LR) is one of these but its role in normal epithelial cells is still unknown. The aim of this study was to characterise the expression pattern and determine the main function of 37/67LR in the normal human small intestinal epithelium. Immunolocalization studies revealed that 37/67LR was predominantly present in the undifferentiated/proliferative region of the human intestinal crypt in both the immature and adult intestine. Using a human intestinal epithelial crypt (HIEC) cell line as experimental model, we determined that 37/67LR was expressed in proliferative cells in both the cytoplasmic and membrane compartments. Small-interfering RNA-mediated reduction of 37/67LR expression led to HIEC cell-cycle reduction and loss of the ability to adhere to laminin-related peptides under conditions not altering ribosomal function. Taken together, these findings indicate that 37/67LR regulates proliferation and adhesion in normal intestinal epithelial cells independently of its known association with ribosomal function.     

T-Cell Infiltration Correlates with CXCL10 Expression in Ganglia of Cynomolgus Macaques with Reactivated Simian Varicella Virus

Ganglia of monkeys with reactivated simian varicella virus (SVV) contained more CD8 than CD4 T cells around neurons. The abundance of CD8 T cells was greater less than 2 months after reactivation than that at later times and correlated with that of CXCL10 RNA but not with those of SVV protein or open reading frame 61 (ORF61) antisense RNA. CXCL10 RNA colocalized with T-cell clusters. After SVV reactivation, transient T-cell infiltration, possibly mediated by CXCL10, parallels varicella zoster virus (VZV) reactivation in humans.