Fabrication of Micropatterns of Aligned Collagen Fibrils.

Many tissues in vivo contain aligned structures such as filaments, fibrils, and fibers, which expose cells to anisotropic structural and topographical cues that range from the nanometer to micrometer scales. Understanding how cell behavior is regulated by these cues during physiological and pathological processes (e.g., wound healing, cancer invasion) requires substrates that can expose cells to anisotropic cues over several length scales. In this study, we developed a novel method of fabricating micropatterns of aligned collagen fibrils of different geometry onto PDMS-coated glass coverslips that allowed us to investigate the roles of topography and confinement on corneal cell behavior. When corneal cells were cultured on micropatterns of aligned collagen fibrils in the absence of confinement, the degree of cell alignment increased from 40 ± 14 to 82 ± 5% as the size of the micropattern width decreased from 750 to 50 µm. Although the cell area (∼2500 µm2), cell length (∼160 µm), and projected nuclear area (∼175 µm2) were relatively constant on the different micropattern widths, cells displayed an increased aspect ratio as the width of the aligned collagen fibril micropatterns decreased. We also observed that the morphology of cells adhering to the surrounding uncoated PDMS was dependent upon both the size of the aligned collagen fibril micropattern and the distance from the micropatterns. When corneal cells were confined to the micropatterns of aligned collagen fibrils by a Pluronic coating to passivate the surrounding area, a similar trend in increasing cell alignment was observed (35 ± 10 to 89 ± 2%). However, the projected nuclear area decreased significantly (∼210 to 130 µm2) as the micropattern width decreased from 750 to 50 µm. The development of this method allows for the deposition of aligned collagen fibril micropatterns of different geometries on a transparent and elastic substrate and provides an excellent model system to investigate the role of anisotropic cues in cell behavior.

Psychometric properties of measures of substance use: a systematic review and meta-analysis of reliability, validity and diagnostic test accuracy.

BACKGROUND: Synthesis of psychometric properties of substance use measures to identify patterns of use and substance use disorders remains limited. To address this gap, we sought to systematically evaluate the psychometric properties of measures to detect substance use and misuse. METHODS: We conducted a systematic review and meta-analysis of literature on measures of substance classes associated with HIV risk (heroin, methamphetamine, cocaine, ecstasy, alcohol) that were published in English before June 2016 that reported at least one of the following psychometric outcomes of interest: internal consistency (alpha), test-retest/inter-rater reliability (kappa), sensitivity, specificity, positive predictive value, and negative predictive value. We used meta-analytic techniques to generate pooled summary estimates for these outcomes using random effects and hierarchical logistic regression models. RESULTS: Findings across 387 paper revealed that overall, 65% of pooled estimates for alpha were in the range of fair-to-excellent; 44% of estimates for kappa were in the range of fair-to-excellent. In addition, 69, 97, 37 and 96% of pooled estimates for sensitivity, specificity, positive predictive value, and negative predictive value, respectively, were in the range of moderate-to-excellent. CONCLUSION: We conclude that many substance use measures had pooled summary estimates that were at the fair/moderate-to-excellent range across different psychometric outcomes. Most scales were conducted in English, within the United States, highlighting the need to test and validate these measures in more diverse settings. Additionally, the majority of studies had high risk of bias, indicating a need for more studies with higher methodological quality.

Can Functional Polymorphisms in VEGF and MMP Predict Intraventricular Hemorrhage in Extremely Preterm Newborns?

BACKGROUND: The pathophysiology of intraventricular hemorrhage (IVH) is multifactorial. This study attempts to identify genetic and clinical factors contributing to IVH in newborns with a focus on those born ≤28 weeks of gestation. METHODS: This was a prospective study of 382 consecutive newborns admitted to the neonatal intensive care unit. DNA purification was conducted using standard methods. TaqMan SNP assays were conducted for functional polymorphisms in VEGF (RS699947, RS2010963, RS3025039, and RS1570360) and MMP2 (RS243685 and RS2285053) genes. An RFLP assay was done for a polymorphism in MMP9 (RS3918242). RESULTS: The GG genotype in VEGF RS1570360 (p = 0.013) and the CC genotype in VEGF RS699947 (p = 0.036) were associated with a lower incidence of IVH amongst newborns ≤28 weeks of gestation. Chorioamnionitis, Caucasian race, and patent ductus arteriosus were associated with a higher incidence of IVH. A binary logistic regression analysis of clinical and SNP data that was significant from bivariate analysis demonstrated that VEGF RS1570360 was significantly associated with IVH (p = 0.017). CONCLUSION: This study demonstrated that the GA/AA genotype in VEGF RS1570360 and the AA/AC genotype in VEGF RS699947 were associated with higher incidence rates of IVH in newborns ≤28 weeks of gestation. A future study is warranted to comprehensively examine VEGF polymorphisms in association with IVH.

Attention: The blue spot reveals one of its secrets.

The locus coeruleus is the seat of a brain-wide neuromodulatory circuit. Using optogenetic and electrophysiological tools to selectively interrogate noradrenergic neurons in non-human primates, Ghosh and Maunsell show how locus coeruleus neurons contribute to a specific aspect of visual attention.

Overcoming big bottlenecks in vascular regeneration.

Bioengineering and regenerative medicine strategies are promising for the treatment of vascular diseases. However, current limitations inhibit the ability of these approaches to be translated to clinical practice. Here we summarize some of the big bottlenecks that inhibit vascular regeneration in the disease applications of aortic aneurysms, stroke, and peripheral artery disease. We also describe the bottlenecks preventing three-dimensional bioprinting of vascular networks for tissue engineering applications. Finally, we describe emerging technologies and opportunities to overcome these challenges to advance vascular regeneration.

Bayesian and Discriminative Models for Active Visual Perception across Saccades.

The brain interprets sensory inputs to guide behavior, but behavior itself disrupts sensory inputs. Perceiving a coherent world while acting in it constitutes active perception. For example, saccadic eye movements displace visual images on the retina and yet the brain perceives visual stability. Because this percept of visual stability has been shown to be influenced by prior expectations, we tested the hypothesis that it is Bayesian. The key prediction was that priors would be used more as sensory uncertainty increases. Humans and rhesus macaques reported whether an image moved during saccades. We manipulated both prior expectations and levels of sensory uncertainty. All psychophysical data were compared with the predictions of Bayesian ideal observer models. We found that humans were Bayesian for continuous judgments. For categorical judgments, however, they were anti-Bayesian: they used their priors less with greater uncertainty. We studied this categorical result further in macaques. The animals' judgments were similarly anti-Bayesian for sensory uncertainty caused by external, image noise, but Bayesian for uncertainty due to internal, motor-driven noise. A discriminative learning model explained the anti-Bayesian effects. We conclude that active vision uses both Bayesian and discriminative models depending on task requirements (continuous vs categorical) and the source of uncertainty (image noise vs motor-driven noise). In the context of previous knowledge about the saccadic system, our results provide an example of how the comparative analysis of Bayesian versus non-Bayesian models of perception offers novel insights into underlying neural organization.

Pelvic Organ Prolapse Severity and Genital Hiatus Size With Long-Term Pessary Use.

OBJECTIVES: To evaluate the association between pessary use more than 1 year and change in prolapse severity. METHODS: This is a secondary analysis of a previously published randomized controlled trial of women undergoing office management of pessaries for management of symptomatic pelvic organ prolapse and incontinence. Primary outcome was change in pelvic organ prolapse quantification measurement genital hiatus (GH). Secondary outcomes included change in prolapse stage, type of pessary, size of pessary, number of pessary changes, and duration of use. Baseline data were collected from the earliest documented examination within the hospital record before pessary placement and compared with their final study visit. Demographics were analyzed using descriptive statistics. Student t test and Mann-Whitney tests were used for categorical comparisons. Pearson and Spearman correlation coefficients were used to evaluate change over time. RESULTS: The cohort was 132 predominantly non-Hispanic White (75%) women with symptomatic prolapse >stage 2 (70.5%). All were postmenopausal. Median duration of pessary use was 39.5 months (interquartile range, 17-64.5 months). Genital hiatus (P = 0.014) and prolapse stage (P = 0.001) decreased as duration of pessary use increased. Those with baseline stages ≥3 had a significant decrease in GH as duration of pessary use increased compared with stages <3 (-0.5 cm vs 0 cm, P < 0.001). There was no difference in change in GH when comparing women with baseline GH less than 3 to 3 cm or greater. CONCLUSIONS: Pessary use by women with pelvic organ prolapse causes a change in vaginal anatomy over time as seen by decreasing stage and point GH.

Corollary Discharge for Action and Cognition.

In motor systems, a copy of the movement command known as corollary discharge is broadcast to other regions of the brain to warn them of the impending movement. The premise of this review is that the concept of corollary discharge may generalize in revealing ways to the brain's cognitive systems. An oculomotor pathway from the brain stem to frontal cortex provides a well-established example of how corollary discharge is instantiated for sensorimotor processing. Building on causal evidence from inactivation of the pathway, we motivate forward models as a tool for understanding the contributions of corollary discharge to perception and movement. Finally, we extend the definition of corollary discharge to account for signals that may be used for cognitive forward models of decision making. This framework may provide new insights into signals and circuits that contribute to sequential decision processes, the breakdown of which may account for some symptoms of psychiatric disorders.

Hyperglycemia is associated with poor outcome in newborn infants undergoing therapeutic hypothermia for hypoxic ischemic encephalopathy.

BACKGROUND: Therapeutic hypothermia (TH) improves survival and neurodevelopmental outcome in neonatal hypoxic ischemic encephalopathy (HIE). Both, hypoglycemia and hyperglycemia are common in infants with HIE. The relationship between hypoglycemia and hyperglycemia, and immediate outcome has not been well described. METHODS: A retrospective analysis of newborn infants with HIE (N = 56) was conducted. Blood glucose concentrations recorded during the first 96 hours were noted. Glucose levels of infants who underwent TH (TH group, N = 20) were compared with those that did not undergo TH (No-TH group, N = 36). The relationship between blood glucose and mortality and/or moderate/severe disability was determined. RESULTS: Mean ± SD blood glucose concentration during the first 24 hours of age was significantly higher in the TH group (148 ± 65 mg/dl), compared with the No-TH group (113 ± 50 mg/dl; p = 0.02), despite a lower glucose infusion rate in the former (4.05 ± 1.77 mg/kg/hr vs. 5.36 ± 2.51 mg/kg/hr; p = 0.04). One hundred percent of infants (n = 9) in the TH group with blood glucose levels >200 mg/dl during the first 24 hours of age died or had moderate/severe disability, compared with 54.5% of those with blood glucose <200 mg/dl in this group (p = 0.03). A similar effect was not present in the No-TH group. CONCLUSION: Hyperglycemia on the first day portends poor outcome in newborn infants undergoing TH for HIE.