Magnetic structure of CuCrO₂: a single crystal neutron diffraction study

This paper presents results of a recent study of multiferroic CuCrO(2) by means of single crystal neutron diffraction. This system has two close magnetic phase transitions at T(N) = 24.2 K and T(mf) = 23.6 K. The low temperature magnetic structure below T(mf) is unambiguously determined to be a fully three-dimensional proper screw. Between T(N) and T(mf) antiferromagnetic order is found that is essentially two-dimensional. In this narrow temperature range, magnetic near neighbor correlations are still long range in the (H,K) plane, whereas nearest neighbors along the L direction are uncorrelated. Thus, the multiferroic state is realized only in the low temperature three-dimensional state and not in the two-dimensional state.

Association of Janus kinase 2 (JAK2) polymorphisms with acute leukemia susceptibility

INTRODUCTION

Aberrant activation of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway leads to deregulated proliferation, differentiation, or apoptosis of normal cells. One of the members of this family, JAK2, plays a very important role in metabolizing carcinogens and medications. This study aimed to detect whether any association exists between genetic polymorphisms in JAK2 gene and individual susceptibility to acute leukemia.

METHODS

A case-control study in a Chinese population with 260 acute leukemia cases and 280 healthy controls matched by age, gender, and ethnicity. Genomic DNA was assayed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) with five genetic polymorphisms in JAK2 gene.

RESULTS

The distributions of rs56118985 GA genotype in the acute leukemia and acute myeloid leukemia (AML) groups were both slightly different when compared with the control group (P = 0.049 and P = 0.045). The frequencies of rs2230724 AA and GA genotypes in the acute leukemia and its subtypes were all significantly higher than that in the control group (P < 0.001). This suggested that subjects with A allele of rs2230724 were susceptible to acute leukemia and its subtypes. In addition, A allele of rs2230724 should be an important genetic determinant for acute leukemia and AML.

CONCLUSION

The results indicate that the risk of acute leukemia might be associated with JAK2 polymorphisms.

Immunohistochemical evidence: testicular and scented glandular androgen synthesis in muskrats (Ondatra zibethicus) during the breeding season

In order to elucidate the relationship between androgens and the function of the muskrat (Ondatra zibethicus) scented glands during the breeding season, we investigated immunolocalization of steroidogenic enzymes P450scc, 3βHSD and P450c17 in the muskrat testes and scented glands. Nine adult muskrats were obtained in March (n=3), May (n=3) and July (n=3) 2010. Steroidogenic enzymes were immunolocalized using polyclonal antisera raised against bovine adrenal P450scc, human placental 3βHSD and porcine testicular P450c17. Histologically, all types of spermatogenic cells including mature-phase spermatozoa in seminiferous tubules were observed in all testes. Glandular cells, interstitial cells, epithelial cells and excretory tubules were identified in scented glands during the breeding season. P450scc, 3βHSD and P450c17 were only identified in Leydig cells during the breeding season; P450scc and P450c17 were observed in glandular cells of scented glands, however, 3βHSD was not found in scented glands during the breeding season. These novel findings provide the first evidence showing that scented glands of the muskrats are capable of locally synthesizing androgens and androgens acting via an endocrine, autocrine or paracrine manner may play an important role in scented gland function during the breeding season.

Altered brain activation and connectivity in early Parkinson disease tactile perception

BACKGROUND AND PURPOSE

Deficits in tactile perception are common in patients with PD. However, the neural mechanisms have not been previously reported in the early stages. This study aims to investigate how the brain activity and connectivity changed under tactile perception at early Parkinsonian state by using functional MR imaging.

MATERIALS AND METHODS

Twenty-one patients with early PD and 22 age- and sex-matched controls were recruited and scanned under a passive tactile stimulation task. Within-group and between-group activation maps were acquired, and regions of interest were defined according to the group-comparison result. This was followed by a functional connectivity analysis based on the graph theory.

RESULTS

We found that in the PD group, bilateral sensorimotor cortex was hypoactive during the task, whereas the hyperactive regions were mainly in bilateral prefrontal cortex, bilateral cerebellum, and contralateral striatum. There was a significant decrease of total connectivity degree in ipsilateral SMA in PD, which was negatively correlated with the Unified Parkinson's Disease Rating Scale score. Furthermore, the connection strengths among the areas of prefrontal cortex, striatum, and cerebellum were increased.

CONCLUSIONS

This study illustrated that early PD was associated with not only altered brain activation but also changed functional connectivity in tactile perception. The most significant impairment was in SMA, whereas striato-prefrontal and cerebello-prefrontal loops may play a compensatory role in early PD tactile function.

Increased expression of the large GTPase dynamin 2 potentiates metastatic migration and invasion of pancreatic ductal carcinoma

Pancreatic ductal tumors invade local parenchyma and metastasize to distant organs. Src-mediated tyrosine kinase signaling pathways promote pancreatic ductal adenocarcinoma (PDAC) metastasis, though the molecular mechanisms supporting this invasive process are poorly understood and represent important and novel therapeutic targets. The large GTPase Dynamin2 (Dyn2), a Src-kinase substrate, regulates membrane-cytoskeletal dynamics although it is yet to be defined if this mechanoenzyme contributes to tumor cell migration and invasion. Therefore the goal of this study was to test if Dyn2 is upregulated in human pancreatic tumors and to define its role in cell migration and metastatic invasion using in vitro assays and nude mouse models. Histological analysis showed that 81% of the 85 patients tested had elevated Dyn2 in PDAC tissue. To test if Dyn2 overexpression alters metastatic properties of human pancreatic tumor cells, stable clones of BxPC-3 cells overexpressing either wild-type Dyn2 or a phosphorylation-deficient mutant Dyn2Y(231/597)F known to attenuate Dyn2 function, were generated and analyzed for migratory capacity. Importantly, tumor cells expressing 2-3 fold levels of Dyn2 protruded lamellipodia at twice the rate, migrated faster (180%) and farther (2.5-fold greater net distance) on glass and through transwell chambers (2-3 fold more cells through the filter) compared to cells expressing Dyn2Y(231/597)F or vector alone. Further, siRNA-mediated depletion of Dyn2 and dynamin inhibitors MiTMAB and Dynasore significantly reduced cell migration (>66%), wound healing (>75%) and invasion in transwell assays (>95%) compared to DMSO treated cells. To test the metastatic potential conferred by increased Dyn2 expression, the BxPC-3 clonal cell lines were implanted orthotopically into the pancreas of nude mice. Cells expressing Dyn2-GFP exhibited a 3-fold increase in large distal tumors compared to cells expressing Dyn2Y(231/597)F or vector alone. Finally, histological analysis of pancreatic metastases from human patients revealed that Dyn2 is upregulated in 60% of metastatic tumors examined. These findings are the first to implicate dynamin in any neoplastic condition and to directly demonstrate a role for this mechanoenzyme in invasive cell migration.

Influence of organic zinc supplementation on the antioxidant status and immune responses of broilers challenged with Eimeria tenella

An experiment was conducted to investigate the influence of Zn supplementation on the performance, antioxidant status, and immune responses of broilers challenged with Eimeria tenella. A total of 384 male broilers (1 d old) were assigned to 8 treatments consisting of 8 replicates of 6 chicks each. A basal corn-soybean meal diet (29.6 mg of Zn/kg) was supplemented with methionine hydroxyl analog-Zn chelate at 0, 20, 40, and 60 mg/kg of diet. At 21 d of age, birds were orally gavaged with 1.5 × 10(4) sporulated E. tenella oocysts. Dietary Zn supplementation had no effect on growth performance of either the challenged or nonchallenged birds. Activities of Cu-Zn superoxide dismutase and glutathione peroxidase were increased (P < 0.001) with increasing Zn levels in both the challenged and nonchallenged groups. Lipid peroxidation tended to be reduced (P = 0.08) at Zn inclusion of 20 and 40 mg/kg. In vitro lymphocyte proliferation responses to mitogen concanavalin A and LPS were not influenced by dietary Zn or challenge. The main effects of Zn level and challenge were significant for secretory IgA on d 28 (P < 0.01) and 35 (P < 0.001). During both periods, secretory IgA of birds receiving dietary Zn supplementation was higher (P < 0.05) than that of those receiving no Zn supplementation. Birds fed Zn supplementation excreted fewer oocysts in the excreta than those receiving no Zn supplement (P < 0.001). Results indicated that organic Zn supplementation reduced oxidative stress and improved some immune responses irrespective of whether birds were healthy or challenged with E. tenella.

Characterization of 236 novel alleles at the HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci from China Marrow Donor Program

Two hundred and thirty-six novel human leukocyte antigen (HLA) alleles are described from volunteer donors of the China Marrow Donor Program: 71 HLA-A alleles, 79 HLA-B alleles, 43 HLA-C, 16 HLA-DRB1 alleles, 26 HLA-DQB1 and 1 HLA-DPB1. Two hundred and thirteen (90.3%) of the 236 novel alleles are single nucleotide substitution variants when compared with their most homologous allele. Seventy-eight of these single nucleotide variants are silent substitutions. The remaining novel alleles differ from their most similar allele by two to four nucleotide substitutions. Some of the novel alleles encode amino acid changes at positions not previously reported to be polymorphic, such as codons 57, 62, 67, 41 and 52 in HLA-A alleles; codons 133, 156, 201 and 215 in HLA-B alleles; codons 74, 208 and 225 in HLA-C; codons 25, 32 and 72 in HLA-DRB1; codons 20, 39 and 77 in HLA-DQB1.

Short-range order and near-field effects on optical scattering and structural coloration

We have investigated wavelength-dependent light scattering in biomimetic structures with short-range order. Coherent backscattering experiments are performed to measure the transport mean free path over a wide wavelength range. Overall scattering strength is reduced significantly due to short-range order and near-field effects. Our analysis explains why single scattering of light is dominant over multiple scattering in similar biological structures and is responsible for color generation.

Characterization of immortalized mesenchymal stem cells derived from foetal porcine pancreas

Islet replacement therapy is limited by shortage of donor islet cells. Usage of islet cells derived from porcine pancreatic stem cells (PSCs) is currently viewed as the most promising alternative for human islet transplantation. However, PSCs are rare and have a finite proliferative lifespan. In this study, we isolated and established an immortalized mesenchymal stem cell (MSC) line derived from foetal porcine pancreas, by transfecting human telomerase reverse transcriptase (hTERT) and called these immortalized pancreatic mesenchymal stem cells (iPMSCs). The iPMSCs have been cultured for more than 80 passages and have capacity to differentiate into neurons, cardiomyocytes, germ cells and islet-like cells, analysed by morphology, RT-PCR, western blotting, immunofluorescence, immunocytochemistry and transplantation assay. Islets derived from iPMSCs reversed hyperglycaemia in streptozotocin-induced diabetic mice and secreted insulin and C-peptide in vitro. These results demonstrated that iPMSCs might provide unlimited resources for islet replacement therapy and models for functional cell differentiation.

Effect of different rumen-inert fatty acids supplemented with a dietary antioxidant on performance and antioxidative status of early-lactation cows

The objective of the study was to evaluate the effect of diets supplemented with fatty acids of different degrees of saturation, in the absence or presence of an antioxidant (AOX; Agrado Plus, Novus International Inc., St. Charles, MO), on dairy cow lactation performance. Calcium salts of long-chain fatty acids were supplemented as a source of lower saturation fatty acid, and a palm acid product was supplemented as the higher saturation fatty acid source. Sixty early-lactation Chinese Holstein cows (100+/-23 d in milk) were randomly allocated to 4 dietary treatments in a 2 x 2 factorial design: (1) lower saturation fatty acid (LS), (2) LS and AOX, (3) higher saturation fatty acid (HS), and (4) HS and AOX. The Ca salts of long-chain fatty acids and palm acid product were supplied at 1.8 and 1.5% on a dry matter basis, respectively, to form isoenergetic diets. The AOX was added at 0.025% in the ration. The experiment lasted 9 wk, including 1 wk for adaptation. Lactation performance was recorded and milk was sampled and analyzed weekly. Blood samples were taken from the coccygeal vein to determine metabolism parameters on d 16, 36, and 56 during the experiment. Neither fatty acid type nor AOX supplementation showed a significant effect on dry matter intake during the study. Milk yield was lower in the LS-fed cows compared with the cows fed HS. Milk fat and milk protein concentrations were not affected by fatty acid type or AOX supplementation. Adding AOX increased the yield of milk in the LS-fed cows, but did not affect those fed HS. Activity of plasma superoxide dismutase was significantly lower, plasma glucose tended to be lower, and plasma malondialdehyde was higher in the LS-fed animals compared with those fed HS. Addition of AOX decreased both plasma nonesterified fatty acids and hydrogen peroxide contents and increased total antioxidant capacity across the fatty acid types. Plasma beta-hydroxybutyrate was not affected by fatty acid type or AOX treatment. Cows fed LS had higher cis-9C(18:1) and trans-10, cis-12C(18:2) in milk at the expense of C(18:0), whereas AOX addition increased milk cis-9C(18:1) at the expense of milk C(12:0), C(16:0), and trans-10, cis-12C(18:2). It is inferred that feeding LS resulted in inferior lactation performance, whereas addition of antioxidant partially alleviated these negative effects.

Directional laser emission from a wavelength-scale chaotic microcavity

We demonstrate directional output from a deformed disk laser of dimensions comparable to the emission wavelength. Unlike larger deformed cavity lasers, which exhibit universal output directionality determined by chaotic ray dynamics, the far-field patterns differ between lasing modes. The directional emission results from weak coupling of isotropic high-quality modes to anisotropic low-quality modes, combined with chiral symmetry breaking of clockwise and counterclockwise propagating waves. This mechanism makes it possible to control the output properties of wavelength-scale lasers.

MicroRNAs play a critical role in tooth development

MicroRNAs are known to regulate gene function in many tissues and organs, but their expression and function, if any, in tooth development are elusive. We sought to identify them by microRNA screening analyses and reveal their overall roles by inactivating Dicer1 in the dental epithelium and mesenchyme. Discrete sets of microRNAs are expressed in molars compared with incisors as well as epithelium compared with mesenchyme. Conditional knockout (cKO) of Dicer1 (mature microRNAs) in the dental epithelium of the Pitx2-Cre mouse results in multiple and branched enamel-free incisors and cuspless molars, and change in incisor patterning and in incisor and molar size and shape. Analyses of differentiating dental epithelial markers reveal a defect in ameloblast differentiation. Conversely, the cervical loop (stem cell niche) is expanded in Dicer1 cKO. These results demonstrate that tooth development is tightly controlled by microRNAs and that specific microRNAs regulate tooth epithelial stem cell differentiation.

Improving optical confinement in nanostructures via external mode coupling

We demonstrate the formation of long-lived resonances via external coupling in open nanostructures. In the examples of three dielectric nanorods or strips, external coupling of modes is induced by tuning of the rod spacing and increases the lifetime over an order of magnitude. Such an enhancement results from the destructive interference of fields that minimizes light leakage. Our results illustrate an effective way of storing light in nanostructures, and have potential applications to nanoscale photonic devices.