High-throughput measurement of human platelet aggregation under flow: application in hemostasis and beyond

In recent years, considerable progress has been made in understanding the mechanisms involved in platelet activation during hemostasis and thrombosis. Parallel-plate flow chambers and other microfluidic devices have markedly contributed to this insight. Conversely, such flow devices are now increasingly used to monitor the combined processes of platelet aggregation, thrombus formation, and coagulation in human blood. Currently, by combining microspotting and multi-color fluorescence microscopy, this technology offers the capability of high-throughput measurement of platelet activation processes, even in small blood samples. Here we review the potential of flow chamber devices for complex (multiparameter) platelet and coagulation phenotyping, focusing on patients with (genetic) platelet- or coagulation-based bleeding disorders as well as monitoring of antithrombotic medication. Animal studies are not discussed.     

The prognostic value of tumour stroma ratio and tumour budding in stage II colon cancer. A nationwide population-based study

Purpose

High-risk patients with stage II colon cancer (CC) may benefit from adjuvant chemotherapy, but additional prognostic markers are needed for better stratification. We investigated the prognostic value of tumour stroma ratio (TSR) and tumour budding (TB).

Methods

A nationwide population-based cohort of 573 patients with stage II CC was included. TSR was scored on hematoxylin and eosin sections as low TSR (>?50% stroma) and high TSR (≤?50% stroma). TB was evaluated in hotspots on pan-cytokeratin stained sections in 10 high power fields (HPF) at the invasive front and classified by the mean number of buds per HPF as high grade budding (≥?10 buds) or low-grade budding (<?10 buds). The prognostic value was investigated in Cox proportional hazard models for recurrence-free survival (RFS) and overall survival (OS).

Results

Low TSR was associated with worse RFS (HR?=?1.342 (95% CI 1.006–1.791), p?=?0.045) and OS (HR?=?1.376 (95% CI 1.016–1.862), p?=?0.039). Furthermore, an association was found between low TSR and microsatellite stabile tumours (p?<?0.001). The mean number of buds per HPF was associated to TSR with increasing number of buds related to a lower TSR (p?=?0.026). No statistically significant prognostic impact of TB regarding OS or RFS was detected.

Conclusions

TSR provided valuable prognostic information, and adding TSR to the current risk stratification may contribute to better patient selection. The estimates of TSR and TB were found to be associated, but no prognostic value of TB was documented.

     

Moderators of the effect of guided online self-help for people with HIV and depressive symptoms

ABSTRACT

The goal of the study was to investigate moderators of intervention effect of a guided Internet-based self-help cognitive behavioral intervention for people with HIV and depressive symptoms. This study was part of a randomized controlled trial where the intervention was found to be effective in reducing depressive symptoms, compared to an attention-only control group. Demographic characteristics (e.g., age), HIV characteristics (e.g., duration of HIV), and psychological characteristics (e.g., coping self-efficacy) were investigated as potential moderators of intervention effect. In 2015, 188 people with HIV and depressive symptoms were included in the study: 97 were randomized to the intervention group and 91 to the control group. Two moderators of intervention effect were found: coping self-efficacy and baseline depression severity. Participants with low coping self-efficacy and baseline depression severity improved more in the intervention group than in the control group, and participants with high coping self-efficacy and baseline depression severity improved in both groups. The results indicate that the intervention may be provided to all people with HIV and depressive symptoms. It may be especially important for people with HIV and low coping self-efficacy to start with the intervention since they show less improvement in the control group with only attention.

Trial registration: Nederlands Trialregister NTR5407, September 11, 2015.     

Growth hormone increases vascular cell adhesion molecule 1 expression: in vivo and in vitro evidence

We investigated the impact of GH administration on endothelial adhesion molecules, vascular cell adhesion molecule-1 (VCAM-1) and E-selectin, in vivo and in vitro. Soluble VCAM-1, E-selectin, and C-reactive protein concentrations were measured before and after treatment in 25 healthy subjects and 25 adult GH-deficient (GHD) patients randomized to GH treatment or placebo. Furthermore, we studied the direct effect of GH and IGF-I and serum from GH-treated subjects on basal and TNF alpha-stimulated expression of VCAM-1 and E-selectin on cultured human umbilical vein endothelial cells. Baseline levels of VCAM-1, but not E-selectin, were significantly lower in GHD patients than in healthy subjects (362 +/- 15 microg/liter vs. 516 +/- 21 microg/liter, P < 0.001) and increased in GHD patients during GH treatment, compared with placebo [net difference between groups 151.8 microg/liter (95% confidence interval: 95.0-208.7 microg/liter); P < 0.0001]. In human umbilical vein endothelial cells, there was no direct stimulatory effect of either GH or IGF-I on the expression of VCAM-1 and E-selectin, but serum from GH-treated healthy subjects significantly increased the expression of VCAM-1 (P < 0.01). Our findings are compatible with the notion that GH may stimulate the expression of VCAM-1 indirectly through modulation of circulating factors. VCAM-1-mediated leukocyte extravasation is implicated in several illnesses including atherosclerosis and multiple-organ failure in sepsis, and we hypothesize that enhanced expression of VCAM-1 may contribute to the detrimental effects of GH in critically ill patients.     

Circulating Extracellular Vesicles Contain miRNAs and are Released as Early Biomarkers for Cardiac Injury

Plasma-circulating microRNAs have been implicated as novel early biomarkers for myocardial infarction (MI) due to their high specificity for cardiac injury. For swift clinical translation of this potential biomarker, it is important to understand their temporal and spatial characteristics upon MI. Therefore, we studied the temporal release, potential source, and transportation of circulating miRNAs in different models of ischemia reperfusion (I/R) injury. We demonstrated that extracellular vesicles are released from the ischemic myocardium upon I/R injury. Moreover, we provided evidence that cardiac and muscle-specific miRNAs are transported by extracellular vesicles and are rapidly detectable in plasma. Since these vesicles are enriched for the released miRNAs and their detection precedes traditional damage markers, they hold great potential as specific early biomarkers for MI.     

From the Cover: No barrier to emergence of bathyal king crabs on the Antarctic shelf

Cold-water conditions have excluded durophagous (skeleton-breaking) predators from the Antarctic seafloor for millions of years. Rapidly warming seas off the western Antarctic Peninsula could now facilitate their return to the continental shelf, with profound consequences for the endemic fauna. Among the likely first arrivals are king crabs (Lithodidae), which were discovered recently on the adjacent continental slope. During the austral summer of 2010‒2011, we used underwater imagery to survey a slope-dwelling population of the lithodid Paralomis birsteini off Marguerite Bay, western Antarctic Peninsula for environmental or trophic impediments to shoreward expansion. The population density averaged ∼4.5 individuals × 1,000 m⁻² within a depth range of 1,100‒1,500 m (overall observed depth range 841–2,266 m). Images of juveniles, discarded molts, and precopulatory behavior, as well as gravid females in a trapping study, suggested a reproductively viable population on the slope. At the time of the survey, there was no thermal barrier to prevent the lithodids from expanding upward and emerging on the outer shelf (400- to 550-m depth); however, near-surface temperatures remained too cold for them to survive in inner-shelf and coastal environments (<200 m). Ambient salinity, composition of the substrate, and the depth distribution of potential predators likewise indicated no barriers to expansion of lithodids onto the outer shelf. Primary food resources for lithodids—echinoderms and mollusks—were abundant on the upper slope (550–800 m) and outer shelf. As sea temperatures continue to rise, lithodids will likely play an increasingly important role in the trophic structure of subtidal communities closer to shore.Climate change is substantially altering the composition and function of marine and terrestrial ecosystems (1–5). Polar-marine communities are particularly vulnerable to climate change, which at this point is the principal threat to their persistence (6). The near-absence of seasonal variation in sea temperature has led to the dominance of cold-stenothermal faunas, which have limited capacities to acclimate to rapid warming (7–9). At polar latitudes, cold-stenothermy and increasing physical disturbance will shift and reduce the geographic ranges of high-latitude marine taxa, increasing their risk of extinction (10–12).Globally accelerating temperature increases are already having profound effects on polar ecosystems. Those impacts extend beyond autecological responses to include top-down and bottom-up effects on marine food webs (13–17). The endemic faunas of the Antarctic continental shelf are now at risk of invasion by durophagous (skeleton-breaking) predators (18), a functional group that (based on the limited paleontological and genetic data available) may not have been ecologically significant there for as long as tens of millions of years (19–22).“Reptant” (bottom-walking) decapod crustaceans, teleostean fishes, and neoselachian sharks and rays are key predators in shallow-subtidal communities worldwide but are at present physiologically excluded from nearshore environments in Antarctica (19). Reptant decapods, which include brachyuran crabs, anomuran crabs, and lobsters, typically cannot survive in waters colder than 1 °C, although adult stages of some of the more cold-tolerant taxa can survive down to 0.4 °C (23, 24). Their limited capacity to down-regulate naturally occurring magnesium ions in their hemolymph leads to paralysis and death at lower temperatures (25).In the absence of durophagous predators, benthic faunas of the Antarctic shelf are lightly skeletonized and dominated by epifaunal suspension-feeders. The top predators are slow-moving invertebrates, such as seastars and nemertean worms. In some respects, therefore, Antarctic-shelf communities are reminiscent of low-predation communities living in contemporary deep-sea habitats, as well as communities from shallow, Paleozoic environments (26–30). Now, as sea temperatures rise, the reintroduction of durophagous predators could radically alter the composition and trophic structure of the shelf-benthos in Antarctica (19, 20, 31).Lithodid crabs (Crustacea: Decapoda: Anomura) are common in the deep sea globally, as well as in shallow waters at subpolar latitudes (32). Also known as king crabs or stone crabs, lithodids feed on a broad range of skeletonized invertebrates, but especially on echinoderms and mollusks (33–36). They are well known from deep-sea habitats of the Southern Ocean and are common in shallow, subantarctic waters (23, 37). Two species, Paralomis birsteini and Neolithodes capensis, were first observed on the continental slope adjacent to the western Antarctic Peninsula (WAP) in 2003, and these sightings were confirmed a few years later (38, 39). P. birsteini appears to be widespread in the Bellingshausen Sea and is the most commonly recorded lithodid species on the slope south of 60° S (18, 23, 37).Phylogenetic evidence suggests multiple radiations of deep-sea lineages of lithodids into the Southern Ocean (32). How long they have been present on the Antarctic continental slope remains controversial (37), and there is virtually no information available on the status and viability of their populations. At some point, adult or larval Neolithodes yaldwyni must have moved over the shelf-break at ∼500 m to establish a reproductively viable population at slope-depths >850 m in Palmer Deep, a trough carved into the shelf of the WAP by glacial movement (40). Lithodids are, however, currently excluded from nearshore, shallow-shelf environments along the WAP, because there the shallowest waters over the shelf are colder than the slope-waters (41–44). Although they are the most cold-tolerant of the reptant decapods, lithodids are still physiologically incapable of surviving below ∼0.4 °C (18, 24, 32).The bathymetric distribution of lithodids could change in the next few decades, however. Summertime sea-surface temperatures and temperatures of the Antarctic Shelf Bottom Waters off the WAP have risen by nearly 1.5 °C over the past 50 y, approximately double the globally averaged rate (45). Rising temperatures in shallow waters off the WAP will likely remove the thermal barrier to lithodids (and other reptant decapods) within the next several decades, facilitating their expansion into shallow, nearshore habitats (18). Judging from the strong, predatory role of invasive lithodids in Arctic food webs (33, 46), as well as the predatory impacts of the brachyuran snow crab Chionoecetes opilio in the Arctic (47), the effects of predation by lithodids could be severe in shallow-benthic communities in Antarctica (19, 40).A recent critique (37) argued correctly that records of lithodids from the Antarctic slope and Palmer Deep do not by themselves constitute evidence that they could or will expand onto the shelf. Such a prediction could, however, be tested with time-series data on the population status and ecology of bathyal lithodids in Antarctica (37). Here, we take a significant first step in addressing that challenge. We describe a dense, reproductively viable population of P. birsteini living on the continental slope off the WAP. We show that there are no apparent physical or ecological barriers to impede the population from immediately expanding upward onto the deeper parts of the adjacent continental shelf, with potentially catastrophic impacts on the existing benthic fauna.     

Aging effects on the resting state motor network and interlimb coordination

Both increases and decreases in resting state functional connectivity have been previously observed within the motor network during aging. Moreover, the relationship between altered functional connectivity and age‐related declines in bimanual coordination remains unclear. Here, we explored the developmental dynamics of the resting brain within a task‐specific motor network in a sample of 128 healthy participants, aged 18–80 years. We found that age‐related increases in functional connectivity between interhemispheric dorsal and ventral premotor areas were associated with poorer performance on a novel bimanual visuomotor task. Additionally, a control analysis performed on the default mode network confirmed that our age‐related increases in functional connectivity were specific to the motor system. Our findings suggest that increases in functional connectivity within the resting state motor network with aging reflect a loss of functional specialization that may not only occur in the active brain but also in the resting brain. Hum Brain Mapp 35:3945–3961, 2014. © 2014 Wiley Periodicals, Inc .     

Baseline sensorimotor GABA levels shape neuroplastic processes induced by motor learning in older adults

Previous research in young adults has demonstrated that both motor learning and transcranial direct current stimulation (tDCS) trigger decreases in the levels of gamma‐aminobutyric acid (GABA) in the sensorimotor cortex, and these decreases are linked to greater learning. Less is known about the role of GABA in motor learning in healthy older adults, a knowledge gap that is surprising given the established aging‐related reductions in sensorimotor GABA. Here, we examined the effects of motor learning and subsequent tDCS on sensorimotor GABA levels and resting‐state functional connectivity in the brains of healthy older participants. Thirty‐six older men and women completed a motor sequence learning task before receiving anodal or sham tDCS to the sensorimotor cortex. GABA‐edited magnetic resonance spectroscopy of the sensorimotor cortex and resting‐state (RS) functional magnetic resonance imaging data were acquired before and after learning/stimulation. At the group level, neither learning nor anodal tDCS significantly modulated GABA levels or RS connectivity among task‐relevant regions. However, changes in GABA levels from the baseline to post‐learning session were significantly related to motor learning magnitude, age, and baseline GABA. Moreover, the change in functional connectivity between task‐relevant regions, including bilateral motor cortices, was correlated with baseline GABA levels. These data collectively indicate that motor learning‐related decreases in sensorimotor GABA levels and increases in functional connectivity are limited to those older adults with higher baseline GABA levels and who learn the most. Post‐learning tDCS exerted no influence on GABA levels, functional connectivity or the relationships among these variables in older adults.     

Backpack palsy and other brachial plexus neuropathies in the military population

Brachial plexus neuropathy is often seen in the military population, especially due to pressure (backpack palsy, BPP) or idiopathic (neuralgic amyotrophy, NA). We aimed to gain insight in the disease characteristics of soldiers with brachial plexus neuropathies in the Dutch military population and to compare disease characteristics between patients with BPP and NA. In this retrospective chart review study we aimed to include all patients with brachial plexus neuropathy, who presented in the Joint Military Hospital between 1 January, 2011 and 31 December, 2016. We calculated the incidence of NA and BPP and Chi‐square tests or Student t tests were performed for differences in patient characteristics between NA and BPP. We included 127 patients, 63 with BPP, 45 with NA, 10 with traumatic brachial plexus neuropathy, and 9 with other plexopathy. The incidence of brachial plexus neuropathy was 50/100 000 person years overall, 25/100 000 person years for BPP, and 18/100 000 person years for NA. Patients in the BPP group differed from the NA with regard to pain (BPP 41% vs NA 93%, P = .000), atrophy (13% BPP vs 29% NA, P = .049), and sensory symptoms (83% BPP vs 44% NA, P = .000). In the BPP group 90% had incomplete recovery and in the NA group 78%. Our study showed a high incidence of BPP and NA in the military population and suggests recovery is not so benevolent as previously thought. Future research is necessary to improve insight and outcome of military patients with brachial plexus neuropathies.