Implementation of HIV early infant diagnosis and HIV type 1 RNA viral load determination on dried blood spots in Cameroon: challenges and propositions

The testing of dried blood spots (DBSs) for human immunodeficiency type 1 (HIV-1) proviral DNA by PCR is a technology that has proven to be particularly valuable in diagnosing exposed infants. We implemented this technology for HIV-1 early infant diagnosis (EID) and HIV-1 RNA viral load determination in infants born of HIV-1-seropositive mothers from remote areas in Cameroon. The samples were collected between December 2007 and September 2010. Fourteen thousand seven hundred and sixty-three (14,763) DBS samples from infants born of HIV-positive mothers in 108 sites nationwide were tested for HIV. Of these, 1452 were positive on first PCR analyses (PCR1), giving an overall infection rate of 12.30%. We received only 475 DBS specimen for a second PCR testing (PCR2); out of these, 145 were positive. The median HIV-1 RNA viral load for 169 infant DBS samples tested was 6.85 log copies/ml, with values ranging from 3.37 to 8 log copies/ml. The determination of the viral load on the same DBS as that used for PCR1 allowed us to bypass the PCR2. The viral load values were high and tend to decrease with age but with a weak slope. The high values of viral load among these infants call for early and effective administration of antiretroviral therapy (ART). The findings from this study indicate that the use of DBS provides a powerful tool for perinatal screening programs, improvement on the testing algorithm, and follow-up during treatment, and thus should be scaled up to the entire nation.     

Assessment of contrast‐enhanced computed tomography for imaging of cartilage during fracture healing

Assessment of the early stages of fracture healing via X‐rays and computed tomography is limited by the low radio‐opacity of cartilage. We validated a method of contrast‐enhanced computed tomography (CECT) for non‐destructive identification of cartilage within a healing fracture callus. Closed, stabilized fractures in femora of C57BL/6 mice were harvested on post‐operative day 9.5 and imaged ex vivo with micro‐computed tomography (µCT) before and after incubation in a cationic contrast agent that preferentially accumulates in cartilage due to the high concentration of sulfated glycosaminoglycans in the tissue. Co‐registration of the pre‐ and post‐incubation images, followed by image subtraction, enabled two‐ and three‐dimensional delineation of mineralized tissue, soft callus, and cartilage. The areas of cartilage and callus identified with CECT were compared to those identified with the gold‐standard method of histomorphometry. No difference was found between the areas of cartilage measured by the two methods (p = 0.999). Callus area measured by CECT was smaller than, but strongly predictive of (R² = 0.80, p < 0.001), the corresponding histomorphometric measurements. CECT also enabled qualitative identification of mineralized cartilage. These findings indicate that the CECT method provides accurate, quantitative, and non‐destructive visualization of the shape and composition of the fracture callus, even during the early stages of repair when little mineralized tissue is present. The non‐destructive nature of this method would allow subsequent analyses, such as mechanical testing, to be performed on the callus, thus enabling higher‐throughput, comprehensive investigations of bone healing. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 567–573, 2013     

Platelet reactivity evaluated with the VASP assay following ticagrelor loading dose in acute coronary syndrome patients undergoing percutaneous coronary intervention

Background

The level of platelet reactivity (PR) inhibition obtained after P2Y12-ADP receptor antagonist loading dose (LD) is associated with the ischemic and bleeding risk following percutaneous coronary intervention (PCI) in acute coronary syndromes (ACS).

Objective

We aimed to evaluate the level of PR inhibition achieved by a 180 mg LD of ticagrelor and the rate of high on-treatment platelet reactivity (HTPR) in ACS patients undergoing PCI.

Methods

We performed a multicentre prospective observational study enrolling ACS patients undergoing PCI. Patients were included if they were admitted for ST-elevation myocardial infarction or non ST-elevation ACS. To assess PR, a VASP index was measured at least 6 and within 24 hours following a 180 mg LD of ticagrelor. HTPR was defined as a VASP index ≥ 50%.

Results

One hundred and fifteen patients were included: 31.3% of STEMI, 49.6% of NSTEMI and 19.1% of unstable angina. Following ticagrelor LD the mean VASP index was 17 ± 14%. However the response to ticagrelor was not uniform with a small inter-individual variability: inter quartile range: 7.6–22.8% and a rate of HTPR of 3.5%. A high number of patients, 65.6%, had a VASP index < 16%. None of the baseline characteristics of the study population was associated with PR. In addition, PR was similar in STEMI, NSTEMI and unstable angina (p = 0.9).

Conclusion

In ACS patients the level of PR inhibition achieved by a 180 mg loading dose of ticagrelor is not uniform and the rate of HTPR is 3.5%. A high proportion of patients exhibited a VASP index < 16%.     

Non‐word repetition in Dutch children with (a risk of) dyslexia and SLI

It has been proposed that poor non‐word repetition is a marker of specific language impairment (SLI), and a precursor and marker of dyslexia. This study investigated whether a non‐word repetition deficit underlies both disorders. A group of Dutch preschool SLI children and children at familial risk of dyslexia, as well as school‐going groups of SLI and dyslexic children were presented with a non‐word repetition task. The results showed that the SLI and the (at‐risk of) dyslexia groups performed more poorly than the control children. Furthermore, with the exception of one child, all preschool SLI children scored significantly below the mean of the preschool control group, suggesting that non‐word repetition performance is a marker of SLI. Approximately half of the at‐risk group were poor performers, which was expected on the basis of the familial risk factor of the at‐risk group. The results show that a non‐word repetition deficit is attested early in life and underlies both dyslexia and SLI.     

Olfactory ensheathing cells form the microenvironment of migrating GnRH‐1 neurons during mouse development

During development, GnRH‐1 neurons differentiate extracerebraly from the nasal placode and migrate from the vomeronasal organ to the forebrain along vomeronasal and terminal nerves. Numerous studies have described the influence of different molecules on the migration of GnRH‐1 neurons, however, the role of microenvironment cells remains poorly understood. This study used GFAP‐GFP transgenic mice to detect glial cells at early developmental stages. Using nasal explant cultures, the comigration of glial cells with GnRH‐1 neurons was clearly demonstrated. This in vitro approach showed that glial cells began migrating from the explants before GnRH‐1 neurons. They remained ahead of the GnRH‐1 migratory front and stopped migrating after the GnRH‐1 neurons. The association of these glial cells with the axons combined with gene expression analysis of GFAP‐GFP sorted cells enabled them to be identified as olfactory ensheathing cells (OEC). Immunohistochemical analysis revealed the presence of multiple glial cell‐type markers showing several OEC subpopulations surrounding GnRH‐1 neurons. Moreover, these OEC expressed genes whose products are involved in the migration of GnRH‐1 neurons, such as Nelf and Semaphorin 4. In situ data confirmed that the majority of the GnRH‐1 neurons were associated with glial cells along the vomeronasal axons in nasal septum and terminal nerves in the nasal forebrain junction as early as E12.5. Overall, these data demonstrate an OEC microenvironment for migrating GnRH‐1 neurons during mouse development. The fact that this glial cell type precedes GnRH‐1 neurons and encodes for molecules involved in their nasal migration suggests that it participates in the GnRH‐1 system ontogenesis. © 2013 Wiley Periodicals, Inc. © 2013 Wiley Periodicals, Inc.     

Purinergic transmission and transglial signaling between neuron somata in the dorsal root ganglion

Most dorsal root ganglion neuronal somata (NS) are isolated from their neighbours by a satellite glial cell (SGC) sheath. However, some NS are associated in pairs, separated solely by the membrane septum of a common SGC to form a neuron–glial cell–neuron (NGlN) trimer. We reported that stimulation of one NS evokes a delayed, noisy and long‐duration inward current in both itself and its passive partner that was blocked by suramin, a general purinergic antagonist. Here we test the hypothesis that NGlN transmission involves purinergic activation of the SGC. Stimulation of the NS triggered a sustained current noise in the SGC. Block of transmission through the NGlN by reactive blue 2 or thapsigargin, a Ca²⁺ store‐depletion agent, implicated a Ca²⁺ store discharge‐linked P2Y receptor. P2Y2 was identified by simulation of the NGlN‐like transmission by puffing UTP onto the SGC and by immunocytochemical localization to the SGC membrane septum. Block of the UTP effect by BAPTA, an intracellular Ca²⁺ scavenger, supported the involvement of SGC Ca²⁺ stores in the signaling pathway. We infer that transmission through the NGlN trimer involves secretion of ATP from the NS and triggering of SGC Ca²⁺ store discharge via P2Y2 receptors. Presumably, cytoplasmic Ca²⁺ elevation leads to the release of an as‐yet unidentified second transmitter from the glial cell to complete transmission. Thus, the two NS of the NGlN trimer communicate via a ‘sandwich synapse’ transglial pathway, a novel signaling mechanism that may contribute to information transfer in other regions of the nervous system.