Evaluation of portable point-of-care CD4 counter with high sensitivity for detecting patients eligible for antiretroviral therapy

Background

Accurate, inexpensive point-of-care CD4+ T cell testing technologies are needed that can deliver CD4+ T cell results at lower level health centers or community outreach voluntary counseling and testing. We sought to evaluate a point-of-care CD4+ T cell counter, the Pima CD4 Test System, a portable, battery-operated bench-top instrument that is designed to use finger stick blood samples suitable for field use in conjunction with rapid HIV testing.

Methods

Duplicate measurements were performed on both capillary and venous samples using Pima CD4 analyzers, compared to the BD FACSCalibur (reference method). The mean bias was estimated by paired Student''s t-test. Bland Altman plots were used to assess agreement.

Results

206 participants were enrolled with a median CD4 count of 396 (range; 18–1500). The finger stick PIMA had a mean bias of −66.3 cells/µL (95%CI −83.4−49.2, P<0.001) compared to the FACSCalibur; the bias was smaller at lower CD4 counts (0–250 cells/µL) with a mean bias of −10.8 (95%CI −27.3−+5.6, P = 0.198), and much greater at higher CD4 cell counts (>500 cells/µL) with a mean bias of −120.6 (95%CI −162.8, −78.4, P<0.001). The sensitivity (95%CI) of the Pima CD4 analyzer was 96.3% (79.1–99.8%) for a <250 cells/ul cut-off with a negative predictive value of 99.2% (95.1–99.9%).

Conclusions

The Pima CD4 finger stick test is an easy-to-use, portable, relatively fast device to test CD4+ T cell counts in the field. Issues of negatively-biased CD4 cell counts especially at higher absolute numbers will limit its utility for longitudinal immunologic response to ART. The high sensitivity and negative predictive value of the test makes it an attractive option for field use to identify patients eligible for ART, thus potentially reducing delays in linkage to care and ART initiation.     

Effects of exposure to pile-driving sounds on the lake sturgeon,Nile tilapia and hogchoker

Pile-driving and other impulsive sound sources have the potential to injure or kill fishes. One mechanism that produces injuries is the rapid motion of the walls of the swim bladder as it repeatedly contacts nearby tissues. To further understand the involvement of the swim bladder in tissue damage, a specially designed wave tube was used to expose three species to pile-driving sounds. Species included lake sturgeon (Acipenser fulvescens)—with an open (physostomous) swim bladder, Nile tilapia (Oreochromis niloticus)—with a closed (physoclistous) swim bladder and the hogchoker (Trinectes maculatus)—a flatfish without a swim bladder. There were no visible injuries in any of the exposed hogchokers, whereas a variety of injuries were observed in the lake sturgeon and Nile tilapia. At the loudest cumulative and single-strike sound exposure levels (SEL_cum and SEL_ss respectively), the Nile tilapia had the highest total injuries and the most severe injuries per fish. As exposure levels decreased, the number and severity of injuries were more similar between the two species. These results suggest that the presence and type of swim bladder correlated with injury at higher sound levels, while the extent of injury at lower sound levels was similar for both kinds of swim bladders.     

Single-cell enabled comparative genomics of a deep ocean SAR11 bathytype

Bacterioplankton of the SAR11 clade are the most abundant microorganisms in marine systems, usually representing 25% or more of the total bacterial cells in seawater worldwide. SAR11 is divided into subclades with distinct spatiotemporal distributions (ecotypes), some of which appear to be specific to deep water. Here we examine the genomic basis for deep ocean distribution of one SAR11 bathytype (depth-specific ecotype), subclade Ic. Four single-cell Ic genomes, with estimated completeness of 55%–86%, were isolated from 770 m at station ALOHA and compared with eight SAR11 surface genomes and metagenomic datasets. Subclade Ic genomes dominated metagenomic fragment recruitment below the euphotic zone. They had similar COG distributions, high local synteny and shared a large number (69%) of orthologous clusters with SAR11 surface genomes, yet were distinct at the 16S rRNA gene and amino-acid level, and formed a separate, monophyletic group in phylogenetic trees. Subclade Ic genomes were enriched in genes associated with membrane/cell wall/envelope biosynthesis and showed evidence of unique phage defenses. The majority of subclade Ic-specfic genes were hypothetical, and some were highly abundant in deep ocean metagenomic data, potentially masking mechanisms for niche differentiation. However, the evidence suggests these organisms have a similar metabolism to their surface counterparts, and that subclade Ic adaptations to the deep ocean do not involve large variations in gene content, but rather more subtle differences previously observed deep ocean genomic data, like preferential amino-acid substitutions, larger coding regions among SAR11 clade orthologs, larger intergenic regions and larger estimated average genome size.     

Comparative genetic mapping reveals synteny and collinearity between the American cranberry and diploid blueberry genomes

Cranberry and blueberry are closely related and recently domesticated fruit crops in the genus Vaccinium. Both have a presumed American origin and likely evolved from a common ancestor; however, details of their adaptive radiation and the extent of their genomic divergence remains little understood. To better understand their evolutionary and genomic relationships, a set of 323 cross-transferable simple sequence repeat (SSR) markers were identified, added to existing marker datasets, and used to construct linkage maps for cranberry (582 SSRs) and an interspecific diploid blueberry population (V. darrowii x V. corymbosum) x V. corymbosum (409 markers, densest blueberry SSR map currently available). The maps allowed for the first comparative genetic mapping study in Vaccinium, and revealed a surprisingly high degree of macro-synteny and collinearity between the cranberry and blueberry genomes. Approximately 93% of the blueberry linkage map was collinear with cranberry, while the remaining 7% (66.3 cM) was spread across 15 non-collinear regions detected in eight of the 12 linkage groups. These observations suggest that large-scale genome differentiation between the cranberry and blueberry genomes has not occurred during their evolution, and that sequence information will be highly transferable between the species in future genetic research and breeding. Finally, the set of 323 cross-transferable SSRs and linkage maps they were used to construct can serve as a shared resource for the Vaccinium research community, enabling additional comparative mapping studies, the identification and transfer of quantitative trait loci and candidate genes between species, and future exploration of evolutionary relationships in Vaccinium.     

EPR detection of heme and nonheme iron-containing protein nitrosylation by nitric oxide during rejection of rat heart allograft.

The paramagnetic molecule nitric oxide (NO), produced from L-arginine by a specific enzyme (NO synthase), has been shown to be involved in a surprising variety of mammalian cellular responses, including the regulation of T cell immunity to alloantigens in vitro. In cytotoxic activated macrophages, NO production results in a characteristic pattern of alteration of iron-containing enzyme function that is mimicked by exposure to NO. Electron paramagnetic resonance (EPR) studies have shown the formation of iron-nitrosyl species during macrophage activation and also during sepsis, indicating that alteration of iron-containing protein function may be the result of the well-documented tendency of NO to bind to metal ions. We have recently shown that the NO synthesis induced during alloantigenic activation of rat splenocytes inhibits lymphocyte proliferation and cytotoxic T-lymphocyte generation. This report demonstrates that iron-nitrosyl EPR signals similar to those observed in macrophages and during sepsis are present in the blood and in the grafted tissue of rats during the rejection of allogeneic (but not syngeneic) heart grafts. These signals are found in the blood and at the site of allograft rejection, but are not found in other tissues (such as spleen and lung), and are obliterated by administration of the immunosuppressant FK506. These results directly demonstrate the formation of iron-nitrosyl complexes during vascularized allograft rejection and suggest that consequent destruction of iron-containing protein function plays an important role in the rejection response.     

Rabbit placental-conditioned medium stimulates progesterone accumulation by granulosa-lutein cells in culture: preliminary characterization of a placental luteotropic hormone

The rabbit fetal placenta plays an important physiological role in luteal maintenance in pregnancy, probably via the secretion of an unidentified placental "luteotropin." The objective of these studies was to examine conditioned medium from fetal placental-tissue incubations (FPI) for the presence of placental luteotropic hormones/factors, using the stimulation of progesterone accumulation by rabbit granulosa-lutein cells in culture, as an in vitro luteotropic bioassay. Progesterone accumulation by rabbit granulosa-lutein cells (during 5 days of culture) was increased (compared with controls), 1.5-fold by 10(-8) M estradiol-17 beta (E2) and 11.5-fold by 100 ng/ml luteinizing hormone (oLH). FPI stimulated progesterone accumulation (approximately 3-fold) and this was further increased in the presence of E2 (FPI + E2; approximately 6-fold). Luteotropic bioactivity in FPI (+ E2) was retained after dialysis (6000-8000 MW cutoff; 7.8-fold) and heating (90-95 degrees C for 1 h; 7.5-fold), but was destroyed after incubation with trypsin (1 mg/ml, 1 h at 37 degrees C; 0.9-fold). Media conditioned with skeletal muscle (1.2-fold), heart (1.6-fold), liver (1.5-fold), and uterus (0.5-fold) and 5-10% serum (less than 1-fold), from pseudopregnant rabbits, had little or no luteotropic bioactivity. These data indicate that FPI contains a luteotropic hormone/factor that is probably a heat-stable, trypsin-sensitive, protein/peptide of greater than 6000-8000 MW that acts in synergy with E2 to promote granulosa-lutein cell steroidogenesis. This placental hormone/factor is a good candidate for the elusive rabbit placental luteotropin.     

Recovery of barotrauma injuries in Chinook salmon, Oncorhynchus tshawytscha from exposure to pile driving sound

Juvenile Chinook salmon, Oncorhynchus tshawytscha, were exposed to simulated high intensity pile driving signals to evaluate their ability to recover from barotrauma injuries. Fish were exposed to one of two cumulative sound exposure levels for 960 pile strikes (217 or 210 dB re 1 μPa(2)·s SEL(cum); single strike sound exposure levels of 187 or 180 dB re 1 μPa(2)?s SEL(ss) respectively). This was followed by an immediate assessment of injuries, or assessment 2, 5, or 10 days post-exposure. There were no observed mortalities from the pile driving sound exposure. Fish exposed to 217 dB re 1 μPa(2)·s SEL(cum) displayed evidence of healing from injuries as post-exposure time increased. Fish exposed to 210 dB re 1 μPa(2)·s SEL(cum) sustained minimal injuries that were not significantly different from control fish at days 0, 2, and 10. The exposure to 210 dB re 1 μPa(2)·s SEL(cum) replicated the findings in a previous study that defined this level as the threshold for onset of injury. Furthermore, these data support the hypothesis that one or two Mild injuries resulting from pile driving exposure are unlikely to affect the survival of the exposed animals, at least in a laboratory environment.     

Proton transfer in the photosynthetic reaction center of Blastochloris viridis

Photosynthetic reaction centers of Blastochloris viridis require two quanta of light to catalyse a two-step reduction of their secondary ubiquinone Q(B) to ubiquinol. We employed capacitive potentiometry to follow the voltage changes that were caused by the accompanying transmembrane proton displacements. At pH 7.5 and 20 degrees C, the Q(B)-related voltage generation after the first flash was contributed by a fast, temperature-independent component with a time constant of approximately 30 micros and a slower component of approximately 200 micros with activation energy (E(a)) of 50 kJ/mol. The kinetics after the second flash featured temperature-independent components of 5 micros and 200 micros followed by a component of 600 micros with E(a) approximately 60 kJ/mol.