Strongly enhanced backward emission of electrons in transfer and ionization

We studied three-dimensional angular distributions and longitudinal momentum spectra of electrons ejected in transfer plus ionization (TI), i.e., the ejection of one and the capture of a second target electron, for ion-helium collisions. We observe a pronounced structure strongly focused opposite to the projectile beam direction, which we associate with a new correlated TI mechanism proposed recently. This process contributes significantly to the total cross sections over a broad range of perturbations η, even at η as large as 0.5, where uncorrelated TI mechanisms were thought to be dominant.

Genetic susceptibility to dental caries on pit and fissure and smooth surfaces

Carious lesions are distributed nonuniformly across tooth surfaces of the complete dentition, suggesting that the effects of risk factors may be surface-specific. Whether genes differentially affect caries risk across tooth surfaces is unknown. We investigated the role of genetics on two classes of tooth surfaces, pit and fissure surfaces (PFS) and smooth surfaces (SMS), in more than 2,600 subjects from 740 families. Participants were examined for surface-level evidence of dental caries, and caries scores for permanent and/or primary teeth were generated separately for PFS and SMS. Heritability estimates (h(2), i.e. the proportion of trait variation due to genes) of PFS and SMS caries scores were obtained using likelihood methods. The genetic correlations between PFS and SMS caries scores were calculated to assess the degree to which traits covary due to common genetic effects. Overall, the heritability of caries scores was similar for PFS (h(2) = 19-53%; p < 0.001) and SMS (h(2) = 17-42%; p < 0.001). Heritability of caries scores for both PFS and SMS in the primary dentition was greater than in the permanent dentition and total dentition. With one exception, the genetic correlation between PFS and SMS caries scores was not significantly different from 100%, indicating that (mostly) common genes are involved in the risk of caries for both surface types. Genetic correlation for the primary dentition dfs (decay + filled surfaces) was significantly less than 100% (p < 0.001), indicating that genetic factors may exert differential effects on caries risk in PFS versus SMS in the primary dentition.

Telocytes in trachea and lungs

We show the existence of a novel type of interstitial cell-telocytes (TC) in mouse trachea and lungs. We used cell cultures, vital stainings, as well as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and immunohistochemistry (IHC). Phase contrast microscopy on cultured cells showed cells with unequivocally characteristic morphology of typical TC (cells with telopodes-Tp). SEM revealed typical TC with two to three Tp-very long and branched cell prolongations. Tp consist of an alternation of thin segments (podomers) and thick segments (podoms). The latter accommodate mitochondria (as shown by Janus Green and MitoTracker), rough endoplasmic reticulum and caveolae. TEM showed characteristic podomers and podoms as well as close relationships with nerve endings and blood capillaries. IHC revealed positive expression of TC for c-kit, vimentin and CD34. In conclusion, this study shows the presence in trachea and lungs of a peculiar type of cells, which fulfils the criteria for TC.

Size scaling and stiffness of avian primary feathers: implications for the flight of Mesozoic birds

The primary feathers of birds are subject to cyclical forces in flight causing their shafts (rachises) to bend. The amount the feathers deflect during flight is dependent upon the flexural stiffness of the rachises. By quantifying scaling relationships between body mass and feather linear dimensions in a large data set of living birds, we show that both feather length and feather diameter scale much closer to predictions for geometric similarity than they do to elastic similarity. Scaling allometry also indicates that the primary feathers of larger birds are relatively shorter and their rachises relatively narrower, compared to those of smaller birds. Two-point bending tests indicated that larger birds have more flexible feathers than smaller species. Discriminant functional analyses (DFA) showed that body mass, primary feather length and rachis diameter can be used to differentiate between different magnitudes of feather bending stiffness, with primary feather length explaining 63% of variance in rachis stiffness. Adding fossil measurement data to our DFA showed that Archaeopteryx and Confuciusornis do not overlap with extant birds. This strongly suggests that the bending stiffness of their primary feathers was different to extant birds and provides further evidence for distinctive flight styles and likely limited flight ability in Archaeopteryx and Confuciusornis.

In vitro and in vivo evaluation of a simple microemulsion formulation for propofol

The aim of the present study was to develop an oil-free o/w microemulsion, composed of pluronic F68, propylene glycol and saline, which solubilized poorly soluble anesthetic drug propofol for intravenous administration. The ternary diagram was constructed to identify the regions of microemulsions, and the optimal composition of microemulsion was determined by in vitro evaluation such as globule size upon dilution and rheology. The droplet size of the diluent emulsion corresponding to oil-in-water type ranged from 200 to 300nm in diameter. Stability analysis of the microemulsions indicated that they were stable upon storage for at least 6 months. Hemolysis percent of propofol microemulsions was lower than that of commercial lipid emulsion (CLE) at 4h. Acute toxicity test showed that median lethal dose of propofol microemulsion was the same as that of CLE. No significant difference in time for unconsciousness and recovery of righting reflex was observed between the prepared microemulsions and CLE. In conclusion, microemulsion would be a promising intravenous delivery system for propofol.

First Report of Damping-Off of Rhodiola sachalinensis Caused by Rhizoctonia solani AG-4 HG-II in China

Rhodiola sachalinensis A. Bor (family Crassulaceae), a perennial herbaceous plant, is distributed mainly in the mountainous areas of China, Japan, Korea, and Russia. It is widely used as a traditional Chinese medicine with adaptogenic properties, cardiopulmonary protective effects, and central nervous system activities (3). Currently, it is extensively cultivated in northeastern China. In August 2010, widespread (>60% of plants were symptomatic) damping-off was observed in a seedling field in Linjiang, China. Leaves and stems near the ground were affected first, with dark lesions forming on the stem and the lowest leaves exhibiting wilt. The wilt spread rapidly over the entire plant with leaves becoming grayish brown and water soaked and then turned black and died. Root rot, defoliation, and damping-off were also observed. Six isolates with morphological characteristics of Rhizoctonia solani Kühn were isolated from symptomatic stems when plated on potato dextrose agar (PDA). Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia after 8 days on PDA. Hyphal cells removed from cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400 magnification. The internal transcribed spacer (ITS) region of the nuclear rDNA was amplified by using the primers ITS4/ITS5 (2). The ITS sequences (715 bp) were identical in these six isolates (GenBank Accession No. FR878087) and had 100% sequence identity with R. solani AG-4 HG-II (GenBank Accession No. HQ629873) along with numerous other accessions from this AG subgroup. Pathogenicity tests were performed on healthy, potted seedlings of R. sachalinensis. Twenty plants were inoculated near the base of the stem with a 0.6-cm-diameter mycelial plug from 3-day-old PDA cultures for each isolate. Twenty plants inoculated with only PDA plugs served as controls. The plants were covered with plastic bags and kept in a greenhouse at 20 to 25°C for 72 h. All inoculated plants showed characteristic symptoms as previously observed in the seedling field 13 days after inoculation, while control plants remained healthy. R. solani AG-4 HG-II was reisolated from symptomatic tissues on inoculated plants. To our knowledge, this is the first report of R. solani AG-4 HG-II causing damping-off on R. sachalinensis in China. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) D. E. L. Cooke et al. Mycol. Res. 101:667, 1997. (3) T. F. Yan et al. Conserv. Genet. 4:213, 2003.

Self-terminating diffraction gates femtosecond X-ray nanocrystallography measurements

X-ray free-electron lasers have enabled new approaches to the structural determination of protein crystals that are too small or radiation-sensitive for conventional analysis¹. For sufficiently short pulses, diffraction is collected before significant changes occur to the sample, and it has been predicted that pulses as short as 10 fs may be required to acquire atomic-resolution structural information^1-4. Here, we describe a mechanism unique to ultrafast, ultra-intense X-ray experiments that allows structural information to be collected from crystalline samples using high radiation doses without the requirement for the pulse to terminate before the onset of sample damage. Instead, the diffracted X-rays are gated by a rapid loss of crystalline periodicity, producing apparent pulse lengths significantly shorter than the duration of the incident pulse. The shortest apparent pulse lengths occur at the highest resolution, and our measurements indicate that current X-ray free-electron laser technology⁵ should enable structural determination from submicrometre protein crystals with atomic resolution.

CTCF and cohesin cooperatively mediate the cell-type specific interchromatin interaction between Bcl11b and Arhgap6 loci

CCCTC-binding factor (CTCF) is a master organizer of genome spatial organization and plays an important role in mediating extensive chromatin interactions. Circular chromosome conformation capture (4C) is a high-throughput approach that allows genome-wide screening for unknown potential interaction partners. Using a conserved CTCF binding site on the Bcl11b locus as bait, an interaction partner at the Arhgap6 locus on a different chromosome was identified by 4C. Additional experiments verified that the interchromatin interaction between the Bcl11b and Arhgap6 loci was cell-type specific, which was cooperatively mediated by CTCF and cohesin. Functional analysis showed that the interchromatin interaction partners were repressing regulatory elements. These results indicate that interaction chromatin loops regulate the expression of the relevant genes.

Effect of ionizing radiation on acinar morphogenesis of human prostatic epithelial cells under three-dimensional culture conditions

Homeostasis is maintained by the interplay of multiple factors that directly or indirectly regulate cell proliferation and cell death. Complex multiple interactions between cells and the extracellular matrix occur during acinar morphogenesis and changes in these might indicate carcinogenesis of cells from a normal to a malignant, invasive phenotype. In this study, the human prostatic epithelial cell line RWPE-1 was cultured under three-dimensional (3-D) culture conditions, and the effect of ionizing radiation on acinar morphogenesis and its association with autophagy were discussed. The results illustrated that formation of specific spheroid (acinar) structures was detectable under 3-D culture conditions. Radiation induced the disruption of acini in different cell models using either gene overexpression (Akt) or gene knock-down (Beclin 1 and ATG7). Introduction of Akt not only accelerated the growth of cells (i.e., caused the cells to manifest elongating and microspike-like structures that are obviously different from structures seen in wild-type RWPE-1 cells under two-dimensional conditions), but also changed their morphological characteristics under 3-D culture conditions. Knock-down of autophagy-related genes (Beclin 1 and ATG7) increased the radiosensitivity of cells under 3-D culture conditions, and cells died of non-apoptotic death after radiation. The results suggested that ionizing radiation may change the cell phenotype and the formation of acini. Additionally even the autophagy mechanism may play a role in these processes.

Biomechanical analysis of proximal junctional kyphosis: preliminary results

Proximal junctional kyphosis (PJK) is a complication related to spinal instrumentation. Defined as a pathological kyphosis of levels above the upper instrumented vertebra, PJK is not yet fully understood although many studies have been conducted in this regard. The objective of this study is therefore to understand the influence of some biomechanical risk factors with respect to PJK. For this purpose, a biomechanical model has been developed and used to test three factors: the sagittal balance, the implant type used at the upper instrumented vertebra (UIV) and the proximal dissection (posterior ligaments disruption and joint capsule degeneration). The preliminary results showed that the PJK is correlated to both sagittal balance and the reduction of spinal stability due to posterior ligaments disruption and joint capsule degeneration.