Effects of CCR5-Delta32 and CCR2-64I alleles on HIV-1 disease progression: the protection varies with duration of infection

OBJECTIVE: To examine temporal variation in the effects of CCR5-Delta32 and CCR2-64I chemokine receptor gene polymorphisms on HIV-1 disease progression. DESIGN: Pooled analysis of individual patient data from 10 cohorts of HIV-1 seroconverters from the United States, Europe, and Australia. METHODS: We studied HIV-1 seroconverters of European (n = 1635) or African (n = 215) ancestry who had been genotyped for CCR5-Delta32 and CCR2-64I. We used Cox proportional hazards models with time-varying coefficients to determine whether the genetic protection against AIDS (1987 case definition) and death varied with time since seroconversion. RESULTS: Protection against AIDS conferred by CCR5-Delta32 held constant at a 31% (RH 0.69, 95% CI 0.54, 0.88) reduction in risk over the course of HIV-1 infection, whereas protection against death held constant at a 39% reduction in risk (RH 0.61, 95% CI 0.45, 0.88). When the period from AIDS to death was isolated, the survival benefit of CCR5-Delta32 diminished 2 years after AIDS. Protection against AIDS conferred by CCR2-64I was greatest early in the disease course. Compared with individuals without CCR5-Delta32 or CCR2-64I, individuals with one or two copies of CCR2-64I had a 58% lower risk of AIDS during the first 4 years after seroconversion (RH 0.42, 95% CI 0.23, 0.76), a 19% lower risk during the subsequent 4 years (RH 0.81, 95% CI 0.59, 1.12), and no significant protection thereafter. CONCLUSION: The protection against AIDS provided by CCR5-Delta32 is continuous during the course of infection. In contrast, the protection provided by CCR2-64I is greatest early in the course of infection.     

Rapid size dependent deletion of foreign gene sequences inserted into attenuated HIV-1 upon infection in vivo: implications for vaccine development

Live attenuated HIV vaccines offer a means to introduce exogenous sequences into the viral genome to target the virus elimination in vivo. Foreign genes inserted into the nef region of HIV-1 NL4-3 were found to be rapidly deleted following virus infection and/or replication, in a size dependent manner, in the human fetal Thymus/Liver implants of severe combined immunodeficient mouse (SCID-hu) model. When the murine heat stable antigen (HSA) of 283 bp was substituted into HIV-1 nef region, the viral loads in vivo were comparable to the negative control nef attenuated HIV-1, and the reporter HSA gene was not deleted upon infection. However, the murine Thy1.2 gene (505 bp) substituted into the nef attenuated HIV-1, upon infection and replication, deleted 441 bp in vitro and 437 bp in vivo, of the inserted Thy1.2 gene. When the enhanced green fluorescence protein (eGFP) gene (720 bp) was substituted for nef, virus replication was aborted in vivo in the Thy/Liv implants, as seen by the background levels of viral loads, comparable to mock infected implants, and the eGFP gene was deleted. When the herpes simplex virus thymidine kinase gene, HSV-TK (1.15 kbp), or HSA gene, was substituted into the viral vpr gene, TK but not HSA gene was deleted, upon infection in vitro. Moreover, NL-TKI reporter virus with both intact nef and vpr genes shows deletion of TK gene both in vitro and in vivo. Excision of foreign genes occurred within the exogenous segments but not in the viral own regions. These results suggest that larger "suicide" genes introduced via HIV-1 can be deleted upon infection. However, smaller size nucleotide sequences or genes (approximately 300 bp) inserted in place of viral nef or vpr gene may be used to target the virus or its components, for attack and elimination in vivo, and thus have implications for the development of live attenuated HIV vaccines.     

Glycoprotein Ib (GPIb)-dependent and GPIb-independent pathways of thrombin-induced platelet activation

In this study, the question of whether glycoprotein Ib (GPIb) mediates both high and moderate affinity pathways of alpha-thrombin-induced platelet activation was examined. Flow cytometric studies, using a panel of monoclonal antibodies (MoAbs), showed that Serratia marcescens protease treatment removed greater than 97% of the glycocalicin portion of GPIb but did not affect the changes in the expression of GPIX or GMP-140 that were induced by high concentrations of alpha-thrombin (10 nmol/L). However, Serratia treatment almost completely abolished the increase in platelet surface GMP-140 induced by low concentrations of alpha-thrombin (0.5 nmol/L) and diminished the downregulation of platelet surface GPIX by 60.9% +/- 5.6% (mean +/- SEM, n = 3). When present in 20-fold molar excess, an MoAb directed against the alpha-thrombin/von Willebrand factor (vWf) binding domains of GPIb completely blocked the ristocetin-dependent binding of vWf to platelets but inhibited only to about 50% the binding of alpha-thrombin and the activation-dependent binding of vWf. In platelets treated with Serratia marcescens protease to remove GPIb, a concentration of this MoAb 16,000-fold in excess of the maximum possible remaining copies of GPIb failed to inhibit platelet activation by alpha-thrombin. These studies demonstrate that activation of intact platelets by alpha-thrombin proceeds by both GPIb-dependent and GPIb-independent mechanisms.     

Effect on iron deficiency anemia of laparoscopic repair of large paraesophageal hernias

Patients with iron deficiency anemia sometimes have a large paraesophageal hernia and no other explanation for their chronic blood loss. The management of these patients can be a dilemma, especially when the hernia is otherwise asymptomatic. We aimed to determine whether a laparoscopic repair of the hernia could cure the anemia. We reviewed a consecutive series of 11 cases of iron deficiency anemia associated with a large paraesophageal hernia, many without associated linear gastric erosions, managed by laparoscopic repair and fundoplication. There was one conversion in a patient with dense adhesions from previous upper abdominal surgery. Another patient required a laparoscopic reoperation for an early recurrence. Major morbidity occurred in three patients and there was no mortality. There was no recurrence of anemia after a median follow-up of more than 2 years. Iron deficiency anemia in association with a large paraesophageal hernia can be treated by laparoscopic repair with acceptable morbidity and minimal mortality. The complications of a large paraesophageal hernia are also prevented.     

Prevalence and severity of paravalvular regurgitation in the Artificial Valve Endocarditis Reduction Trial (AVERT) echocardiography study

OBJECTIVES: The purpose of this study was to determine the prevalence and severity of paravalvular regurgitation (PVR) in the Artificial Valve Endocarditis Reduction Trial (AVERT) cohort. BACKGROUND: The initial AVERT cohort consisted of 807 patients randomized to receive either a Silzone-coated prosthetic valve or a conventional prosthetic valve; early clinical reports showed higher rates of valve explant caused by PVR for Silzone-coated prosthetic valve. METHODS: Of the 678 eligible patients, 575 (85%) underwent postoperative transthoracic echocardiograms. The presence and severity of PVR were identified by color flow Doppler. Reviewers were blinded to the type of prosthetic valve and the demographic and clinical variables. RESULTS: Among those who underwent echocardiography (Silzone-coated prosthetic valve, n = 285 and conventional prosthetic valve, n = 290), 59% had prosthetic aortic valves, 32% prosthetic mitral valves, and 9% had both; demographic and clinical findings (i.e., prosthetic valve endocarditis, thromboembolism, bleeding, and all-cause death) were similar for the two groups. Echocardiographically determined PVR was present in 50 valves: Silzone-coated prosthetic valve, 29 of 285 (10%) and conventional prosthetic valve, 21 of 290 (7%, p = NS); the severity of PVR was similar in both groups. Kaplan-Meier analysis showed no significant differences in PVR at 24 months from valve implantation between the two groups (24-month event-free rate: 93% Silzone-coated prosthetic valve vs. 94% conventional prosthetic valve, p = NS). CONCLUSIONS: Excluding those patients who had initial prosthetic valve explant, the two-year echocardiographic follow-up of the AVERT cohort shows no statistically significant differences in the prevalence or severity of PVR in the Silzone-coated prosthetic valve compared with the conventional prosthetic valve. Further monitoring is warranted to determine whether these clinical outcomes remain similar on long-term follow-up.     

Rolling back malaria: how well is Europe doing?

Background. The Roll Back Malaria (RBM) initiative has committed itself to halving the worlds's malaria burden by 2010, having adopted five operationally focused 'critical concepts' to guide this task. The focus of RBM's efforts is in the developing world where external support is often required. Malaria was only recently eradicated from Europe, and the continent remains under continual threat of reintroduction. The extent of this threat is examined, and the European response benchmarked against RBM's critical concepts. Methods. The following sources were searched for references using the phrase "imported malaria": RBM, WHO, European Union including Eurosurveillance, and MedLine websites. Links to related articles were followed. Citations were independently assessed by the authors for relevance and inclusion. Results. Only in application of the critical concept "disease surveillance" does the European response seem adequate. Conclusions. Europe should be making greater efforts and considering additional strategies to combat imported malaria.     

Molecular basis of sequestration in severe and uncomplicated Plasmodium falciparum malaria: differential adhesion of infected erythrocytes to CD36 and ICAM-1.

The CD36 and ICAM-1 glycoproteins on vascular endothelial cells have been implicated as cytoadherence receptors for Plasmodium falciparum-infected erythrocytes (IRBC). Adhesion of IRBC from Thai patients with uncomplicated and severe falciparum malaria to purified CD36 or ICAM-1 and to C32 melanoma cells was compared. All malaria isolates bound to solid phase-adsorbed CD36 and to fluid-phase 125I-labeled CD36. IRBC adhesion to purified ICAM-1 varied widely, and no correlation with clinical severity of disease was observed. The cytoadherent phenotype of IRBC was modulated by selective panning on plates coated with purified CD36 or ICAM-1. IRBC selected by panning on CD36+, ICAM-1+ melanoma cells bound to cells that express surface CD36 but not to CD36-deficient cells, indicating that CD36 exerts a strong selective pressure on the IRBC cytoadherent phenotype. IRBC adhesion to CD36 and ICAM-1 suggests that P. falciparum parasites may use these receptors in vivo to promote parasite survival and immune evasion.