Tough adhesives for diverse wet surfaces

Adhesion to wet and dynamic surfaces, including biological tissues, is important in many fields but has proven to be extremely challenging. Existing adhesives are cytotoxic, adhere weakly to tissues, or cannot be used in wet environments. We report a bioinspired design for adhesives consisting of two layers: an adhesive surface and a dissipative matrix. The former adheres to the substrate by electrostatic interactions, covalent bonds, and physical interpenetration. The latter amplifies energy dissipation through hysteresis. The two layers synergistically lead to higher adhesion energies on wet surfaces as compared with those of existing adhesives. Adhesion occurs within minutes, independent of blood exposure and compatible with in vivo dynamic movements. This family of adhesives may be useful in many areas of application, including tissue adhesives, wound dressings, and tissue repair.

A calcineurin-dependent transcriptional pathway controls skeletal muscle fiber type

Slow- and fast-twitch myofibers of adult skeletal muscles express unique sets of muscle-specific genes, and these distinctive programs of gene expression are controlled by variations in motor neuron activity. It is well established that, as a consequence of more frequent neural stimulation, slow fibers maintain higher levels of intracellular free calcium than fast fibers, but the mechanisms by which calcium may function as a messenger linking nerve activity to changes in gene expression in skeletal muscle have been unknown. Here, fiber-type-specific gene expression in skeletal muscles is shown to be controlled by a signaling pathway that involves calcineurin, a cyclosporin-sensitive, calcium-regulated serine/threonine phosphatase. Activation of calcineurin in skeletal myocytes selectively up-regulates slow-fiber-specific gene promoters. Conversely, inhibition of calcineurin activity by administration of cyclosporin A to intact animals promotes slow-to-fast fiber transformation. Transcriptional activation of slow-fiber-specific transcription appears to be mediated by a combinatorial mechanism involving proteins of the NFAT and MEF2 families. These results identify a molecular mechanism by which different patterns of motor nerve activity promote selective changes in gene expression to establish the specialized characteristics of slow and fast myofibers.

Requirement of Math1 for secretory cell lineage commitment in the mouse intestine

The mouse small intestinal epithelium consists of four principal cell types deriving from one multipotent stem cell: enterocytes, goblet, enteroendocrine, and Paneth cells. Previous studies showed that Math1, a basic helix-loop-helix (bHLH) transcription factor, is expressed in the gut. We find that loss of Math1 leads to depletion of goblet, enteroendocrine, and Paneth cells without affecting enterocytes. Colocalization of Math1 with Ki-67 in some proliferating cells suggests that secretory cells (goblet, enteroendocrine, and Paneth cells) arise from a common progenitor that expresses Math1, whereas absorptive cells (enterocytes) arise from a progenitor that is Math1-independent. The continuous rapid renewal of these cells makes the intestinal epithelium a model system for the study of stem cell regeneration and lineage commitment.

5,10-Methylenetetrahydrofolate reductase gene variants and congenital anomalies: a HuGE review

The enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR) is involved in folate metabolism. The MTHFR gene is located on chromosome 1 (1p36.3), and two common alleles, the C677T (thermolabile) allele and the A1298C allele, have been described. The population frequency of C677T homozygosity ranges from 1% or less among Blacks from Africa and the United States to 20% or more among Italians and US Hispanics. C677T homozygosity in infants is associated with a moderately increased risk for spina bifida (pooled odds ratio = 1.8; 95% confidence interval: 1.4, 2.2). Maternal C677T homozygosity also appears to be a moderate risk factor (pooled odds ratio = 2.0; 95% confidence interval: 1.5, 2.8). The A 1298C allele combined with the C677T allele also could be associated with an increased risk for spina bifida. Some data suggest that the risk for spina bifida associated with C677T homozygosity may depend on nutritional status (e.g., blood folate levels, intake of vitamins) or on the genotype of other folate-related genes (e.g., cystathionine-beta-synthase and methionine synthase reductase). Studies of the C677T allele in relation to oral clefts, Down syndrome, and fetal anticonvulsant syndrome either have yielded conflicting results or have not been yet replicated.

Anomalously low dielectric constant of confined water

The dielectric constant ε of interfacial water has been predicted to be smaller than that of bulk water (ε ≈ 80) because the rotational freedom of water dipoles is expected to decrease near surfaces, yet experimental evidence is lacking. We report local capacitance measurements for water confined between two atomically flat walls separated by various distances down to 1 nanometer. Our experiments reveal the presence of an interfacial layer with vanishingly small polarization such that its out-of-plane ε is only ~2. The electrically dead layer is found to be two to three molecules thick. These results provide much-needed feedback for theories describing water-mediated surface interactions and the behavior of interfacial water, and show a way to investigate the dielectric properties of other fluids and solids under extreme confinement.

Mortality Associated With Congenital Heart Defects in the United States

Background —Surgical series and some population-based studies have documented a decrease in mortality from heart defects. Recent population-based data for the United States are lacking, however. We examined population-based data for patterns, time trends, and racial differences of mortality from heart defects for the United States from 1979 through 1997.

Methods and Results —We examined the multiple-cause mortality files compiled by the National Center for Health Statistics of the CDC from all death certificates filed in the United States. From these data, we derived death rates (deaths per 100 000 population) by the decedent’s age, race, year of death, and heart defect type. We also analyzed age at death as an indirect indicator of survival. From 1979 through 1997, mortality from heart defects (all ages) declined 39%, from 2.5 to 1.5 per 100 000 population; among infants, the decline was 39%, or 2.7% per year. In 1995 to 1997, heart defects contributed to 5822 deaths per year. Of these deaths, 51% were among infants and 7% among children 1 to 4 years old. Mortality was on average 19% higher among blacks than among whites; this gap does not appear to be closing. Age at death increased for most heart defects, although less among blacks than among whites.

Conclusions —Mortality from heart defects is declining in the United States, although it remains a major cause of death in infancy and childhood. Age at death is increasing, suggesting that more affected persons are living to adolescence and adulthood. The racial discrepancies should be investigated to identify opportunities for prevention.

Mortality in neurofibromatosis 1: an analysis using U.S. death certificates

Although neurofibromatosis 1 (NF1) is a relatively common autosomal dominant condition, information about its effect on mortality is limited. We used Multiple-Cause Mortality Files, compiled from U.S. death certificates by the National Center for Health Statistics, for 1983 through 1997. We identified 3,770 cases of presumed NF1 among 32,722,122 deaths in the United States, a frequency of 1/8,700, which is one-third to one-half the estimated prevalence. Mean and median ages at death for persons with NF1 were 54.4 and 59 years, respectively, compared with 70.1 and 74 years in the general population. Results of proportionate mortality ratio (PMR) analyses showed that persons with NF1 were 34 times more likely (PMR=34.3, 95% confidence interval [CI] 30.8-38.0) to have a malignant connective or other soft-tissue neoplasm listed on their death certificates than were persons without NF1. Overall, persons with NF1 were 1.2 times more likely than expected (PMR=1.21, 95% CI 1.14-1.28) to have a malignant neoplasm listed on their death certificates, but the PMR was 6.07 (95% CI 4.88-7.45) for persons who died at 10-19 years of age and was 4.93 (95% CI 4.14-5.82) for those who died at 20-29 years of age. Similarly, vascular disease was recorded more often than expected on death certificates of persons with NF1 who died at <30 years of age (PMR=3.26, 95% CI 1.31-6.71 at age <10 years; PMR=2.68, 95% CI 1.38-4.68 at age 10-19 years; and PMR=2.25, 95% CI 1.46-3.32 at 20-29 years) but not in older persons. This study supports previous findings of decreased life expectancy for persons with NF1 and, within the limitations of death certificates, provides population-based data about NF1 morbidity and mortality that are useful to clinicians caring for patients with NF1.

Prediction of stroke outcome with echoplanar perfusion- and diffusion-weighted MRI

OBJECTIVES

We examined the utility of echoplanar magnetic resonance perfusion imaging and diffusion-weighted imaging (DWI) in predicting stroke evolution and outcome in 18 patients with acute hemispheric infarction.

METHODS

Patients were studied within 24 hours (mean, 12.2 hours), subacutely (mean, 4.7 days), and at outcome (mean, 84 days). Comparisons were made between infarction volumes as measured on perfusion imaging (PI) and isotropic DWI maps, clinical assessment scales (Canadian Neurological Scale, Barthel Index, and Rankin Scale), and final infarct volume (T2-weighted MRI).

RESULTS

Acute PI lesion volumes correlated with acute neurologic state, clinical outcome, and final infarct volume. Acute DWI lesions correlated less robustly with acute neurologic state, but correlated well with clinical outcome and final infarct volume. Three of six possible patterns of abnormalities were seen: PI lesion larger than DWI lesion (65%), PI lesion smaller than DWI lesion (12%), and DWI lesion but no PI lesion (23%). A pattern of a PI lesion larger than the DWI lesion predicted DWI expansion into surrounding hypoperfused tissue (p < 0.05). In the other two patterns, DWI lesions did not enlarge, suggesting that no significant increase in ischemic lesion size occurs in the absence of a larger perfusion deficit.

CONCLUSIONS

Combined early PI and DWI can define different acute infarct patterns, which may allow the selection of rational therapeutic strategies based on the presence or absence of potentially salvageable ischemic tissue.

Adaptation of innate lymphoid cells to a micronutrient deficiency promotes type 2 barrier immunity

How the immune system adapts to malnutrition to sustain immunity at barrier surfaces, such as the intestine, remains unclear. Vitamin A deficiency is one of the most common micronutrient deficiencies and is associated with profound defects in adaptive immunity. Here, we found that type 3 innate lymphoid cells (ILC3s) are severely diminished in vitamin A-deficient settings, which results in compromised immunity to acute bacterial infection. However, vitamin A deprivation paradoxically resulted in dramatic expansion of interleukin-13 (IL-13)-producing ILC2s and resistance to nematode infection in mice, which revealed that ILCs are primary sensors of dietary stress. Further, these data indicate that, during malnutrition, a switch to innate type 2 immunity may represent a powerful adaptation of the immune system to promote host survival in the face of ongoing barrier challenges.

Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation

Graphene oxide (GO) membranes continue to attract intense interest due to their unique molecular sieving properties combined with fast permeation. However, their use is limited to aqueous solutions because GO membranes appear impermeable to organic solvents, a phenomenon not yet fully understood. Here, we report efficient and fast filtration of organic solutions through GO laminates containing smooth two-dimensional (2D) capillaries made from large (10-20 μm) flakes. Without modification of sieving characteristics, these membranes can be made exceptionally thin, down to ∼10 nm, which translates into fast water and organic solvent permeation. We attribute organic solvent permeation and sieving properties to randomly distributed pinholes interconnected by short graphene channels with a width of 1 nm. With increasing membrane thickness, organic solvent permeation rates decay exponentially but water continues to permeate quickly, in agreement with previous reports. The potential of ultrathin GO laminates for organic solvent nanofiltration is demonstrated by showing >99.9% rejection of small molecular weight organic dyes dissolved in methanol. Our work significantly expands possibilities for the use of GO membranes in purification and filtration technologies.

Sickle hemoglobin (HbS) allele and sickle cell disease: a HuGE review

Sickle cell disease is caused by a variant of the beta-globin gene called sickle hemoglobin (Hb S). Inherited autosomal recessively, either two copies of Hb S or one copy of Hb S plus another beta-globin variant (such as Hb C) are required for disease expression. Hb S carriers are protected from malaria infection, and this protection probably led to the high frequency of Hb S in individuals of African and Mediterranean ancestry. Despite this advantage, individuals with sickle cell disease exhibit significant morbidity and mortality. Symptoms include chronic anemia, acute chest syndrome, stroke, splenic and renal dysfunction, pain crises, and susceptibility to bacterial infections. Pediatric mortality is primarily due to bacterial infection and stroke. In adults, specific causes of mortality are more varied, but individuals with more symptomatic disease may exhibit early mortality. Disease expression is variable and is modified by several factors, the most influential being genotype. Other factors include beta-globin cluster haplotypes, alpha-globin gene number, and fetal hemoglobin expression. In recent years, newborn screening, better medical care, parent education, and penicillin prophylaxis have successfully reduced morbidity and mortality due to Hb S.

Biofilm maturity studies indicate sharp debridement opens a time- dependent therapeutic window

OBJECTIVE

To investigate the hypothesis that newly formed wound biofilms (or bioburdens) are more susceptible to antimicrobial treatment.

METHOD

Four separate and distinct models were performed by four separate biofilm research laboratories to evaluate the resistance of biofilms to antimicrobial treatments over time. These included a drip-flow biofilm model along with a hydrodebridement study, a porcine skin punch biopsy ex vivo model, a mouse chronic wound model and clinical longitudinal debridement study.

RESULTS

All four models showed that, within the first 24 hours, the biofilm community was more susceptible to the selected antibiotics, and after maturing for up to 48 hours became increasingly tolerant. In each model, there was at least a 24-hour period in which the biofilms were more resistant to antibiotics. Each of the models utilised showed a significant decrease in the resistance of the biofilm/ burden to gentamicin for up to 24 hours with a confidence interval of at least 95%. The resistance increased in each of the models by 48 hours and reached original resistance levels by 72 hours.

CONCLUSION

These data suggest the principles of biofilm-based wound care, along with the use of serial debridement to continually remove mature biofilm, followed by biofilm wound management strategies, including topical antibiotics while the bioburden is still immature and more susceptible, are valid.

Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949)

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

Three-dimensional architecture of the isolated yeast nuclear pore complex: functional and evolutionary implications

We have calculated a three-dimensional map of the yeast nuclear pore complex (yNPC) from frozen-hydrated specimens, thereby providing a direct comparison with the vertebrate NPC. Overall, the smaller yNPC is comprised of an octagonal inner spoke ring that is anchored within the nuclear envelope by a novel membrane-interacting ring. In addition, a cylindrical transporter is located centrally within the spokes and exhibits a variable radial expansion in projection that may reflect gating. The inner spoke ring, a transmembrane spoke domain, and the transporter are conserved between yeast and vertebrates; hence, they are required to form a functional NPC. However, significant alterations in NPC architecture have arisen during evolution that may be correlated with differences in nuclear transport regulation or mitotic behavior.

Resistance trends among clinical isolates in China reported from CHINET surveillance of bacterial resistance, 2005-2014

With the aim of gathering temporal trends on bacterial epidemiology and resistance from multiple laboratories in China, the CHINET surveillance system was organized in 2005. Antimicrobial susceptibility testing was carried out according to a unified protocol using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2014 definitions. Between 2005 and 2014, the number of bacterial isolates ranged between 22,774 and 84,572 annually. Rates of extended-spectrum β-lactamase production among Escherichia coli isolates were stable, between 51.7 and 55.8%. Resistance of E. coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, piperacillin/tazobactam and cefoperazone/sulbactam decreased with time. Carbapenem resistance among K. pneumoniae isolates increased from 2.4 to 13.4%. Resistance of Pseudomonas aeruginosa strains against all of antimicrobial agents tested including imipenem and meropenem decreased with time. On the contrary, resistance of Acinetobacter baumannii strains to carbapenems increased from 31 to 66.7%. A marked decrease of methicillin resistance from 69% in 2005 to 44.6% in 2014 was observed for Staphylococcus aureus. Carbapenem resistance rates in K. pneumoniae and A. baumannii in China are high. Our results indicate the importance of bacterial surveillance studies.

HLA-B*13:01 and the dapsone hypersensitivity syndrome

BACKGROUND

Dapsone is used in the treatment of infections and inflammatory diseases. The dapsone hypersensitivity syndrome, which is associated with a reported mortality of 9.9%, develops in about 0.5 to 3.6% of persons treated with the drug. Currently, no tests are available to predict the risk of the dapsone hypersensitivity syndrome.

METHODS

We performed a genomewide association study involving 872 participants who had received dapsone as part of multidrug therapy for leprosy (39 participants with the dapsone hypersensitivity syndrome and 833 controls), using log-additive tests of single-nucleotide polymorphisms (SNPs) and imputed HLA molecules. For a replication analysis, we genotyped 24 SNPs in an additional 31 participants with the dapsone hypersensitivity syndrome and 1089 controls and performed next-generation sequencing for HLA-B and HLA-C typing at four-digit resolution in an independent series of 37 participants with the dapsone hypersensitivity syndrome and 201 controls.

RESULTS

Genomewide association analysis showed that SNP rs2844573, located between the HLA-B and MICA loci, was significantly associated with the dapsone hypersensitivity syndrome among patients with leprosy (odds ratio, 6.18; P=3.84×10(-13)). HLA-B*13:01 was confirmed to be a risk factor for the dapsone hypersensitivity syndrome (odds ratio, 20.53; P=6.84×10(-25)). The presence of HLA-B*13:01 had a sensitivity of 85.5% and a specificity of 85.7% as a predictor of the dapsone hypersensitivity syndrome, and its absence was associated with a reduction in risk by a factor of 7 (from 1.4% to 0.2%). HLA-B*13:01 is present in about 2 to 20% of Chinese persons, 1.5% of Japanese persons, 1 to 12% of Indians, and 2 to 4% of Southeast Asians but is largely absent in Europeans and Africans.

CONCLUSIONS

HLA-B*13:01 was associated with the development of the dapsone hypersensitivity syndrome among patients with leprosy. (Funded by the National Natural Science Foundation of China and others.).

Accounting for unmeasured population substructure in case-control studies of genetic association using a novel latent-class model

We propose a novel latent-class approach to detect and account for population stratification in a case-control study of association between a candidate gene and a disease. In our approach, population substructure is detected and accounted for using data on additional loci that are in linkage equilibrium within subpopulations but have alleles that vary in frequency between subpopulations. We have tested our approach using simulated data based on allele frequencies in 12 short tandem repeat (STR) loci in four populations in Argentina.

Pathophysiological topography of acute ischemia by combined diffusion-weighted and perfusion MRI

BACKGROUND AND PURPOSE

Combined echoplanar MRI diffusion-weighted imaging (DWI), perfusion imaging (PI), and magnetic resonance angiography (MRA) can be used to visualize acute brain ischemia and predict lesion evolution and functional outcome. The appearance of a larger lesion by PI than by DWI quantitatively defines a mismatch of potential clinical importance. Qualitative lesion variations exist in the topographic concordance of this mismatch. We examined both the topographic heterogeneity and relative frequency of mismatched patterns in acute stroke using these MRI techniques.

METHODS

Acute DWI, PI, and MRA studies of 34 prospectively recruited patients with supratentorial ischemic lesions scanned within 24 hours of stroke onset (range 2.5 to 23.3 hours, 12 patients <6 hours) were analyzed.

RESULTS

Ischemic lesions were predominantly in the middle cerebral artery (MCA) territory (94%), with DWI lesions most commonly affecting the insular region. Mismatched patterns with PI lesion larger than DWI lesion occurred in 21 patients (62% overall), in all 4 patients imaged within 3 hours, and in 44% of patients imaged after 18 hours. A patient with a large PI but no DWI lesion and severe clinical deficit at 2.5 hours after stroke onset recovered completely. Regional variations in DWI and PI lesion loci were found, inferring site of proximal MCA occlusion, embolic pathogenesis, and regional arterial reperfusion.

CONCLUSIONS

Analysis of the topographic concordance of PI and DWI lesions in acute stroke reveals regional PI lesions without concomitant DWI lesions, which do not necessarily progress to infarction but may suggest stroke pathogenesis and site of current arterial occlusion. Location of DWI lesions may suggest an earlier site of arterial occlusion and regions of maximal perfusion deficit.

Vasoactive intestinal peptide-receptor imaging for the localization of intestinal adenocarcinomas and endocrine tumors

BACKGROUND

Intestinal adenocarcinomas and various endocrine tumors express large numbers of high-affinity receptors for vasoactive intestinal peptide (VIP). We have evaluated the usefulness of scanning with VIP labeled with iodine-123 for tumor localization in patients with gastrointestinal tumors.

METHODS

Radioiodinated VIP was purified by high-pressure liquid chromatography and administered as a single intravenous bolus injection (300 pmol [1 microgram]). Scanning with radiolabeled VIP was compared with computed tomography and scanning with somatostatin analogues in 79 patients with colorectal cancer, pancreatic carcinoma, gastric cancer, carcinoid tumor, or insulinoma.

RESULTS

Visualization of gastrointestinal tumors and metastases was obtained with radiolabeled VIP. Binding of the labeled peptide by primary tumors and metastases was visible shortly after the injection and was still demonstrable at 24 hours. In patients with colorectal adenocarcinomas, primary or recurrent tumors were visualized in 10 of 10, liver metastases in 15 of 18, lung metastases in 2 of 3, and lymph-node metastases in 4 of 4. Primary pancreatic adenocarcinomas were visualized by imaging in 10 of 12 patients, and liver metastases were seen in 7 of 7. Primary or recurrent gastric adenocarcinomas were visualized in 5 of 5 patients, and liver metastases were seen in 2 of 2 patients. VIP scans were positive in 9 of 10 patients with carcinoid tumors and in 4 of 4 patients with insulinomas. Some tumors with positive VIP scans were also visualized with somatostatin analogues (4 of 17 colorectal adenocarcinomas, 8 of 9 carcinoids, and 2 of 2 insulinomas). In vitro binding studies confirmed the presence of VIP receptors on gastrointestinal tumors.

CONCLUSIONS

Scanning with radiolabeled VIP can visualize intestinal tumors and metastases that express receptors for VIP.