Visualizing the mixed bonding properties of liquid boron with high-resolution x-ray Compton scattering.

Bonding characteristics of liquid boron at 2500 K are studied by using high-resolution Compton scattering. An excellent agreement is found between the measurements and the corresponding Car-Parrinello molecular dynamics simulations. Covalent bond pairs are clearly shown to dominate in liquid boron along with the coexistence of diffuse pairs. Our study reveals the complex bonding pattern of liquid boron and gives insight into the unusual properties of this high-temperature liquid.

Persistence of covalent bonding in liquid silicon probed by inelastic x-ray scattering.

Metallic liquid silicon at 1787 K is investigated using x-ray Compton scattering. An excellent agreement is found between the measurements and the corresponding Car-Parrinello molecular dynamics simulations. Our results show persistence of covalent bonding in liquid silicon and provide support for the occurrence of theoretically predicted liquid-liquid phase transition in supercooled liquid states. The population of covalent bond pairs in liquid silicon is estimated to be 17% via a maximally localized Wannier function analysis. Compton scattering is shown to be a sensitive probe of bonding effects in the liquid state.

Factors associated with lobar vs. non-lobar intracerebral hemorrhage.

OBJECTIVES: The relationship between body mass index (BMI) and stroke subtypes has received more research attention than that between BMI and location of intracerebral hemorrhage (ICH). Lobar hemorrhage (LH) differs from non-LH primarily in terms of etiology, i.e. cerebral amyloid angiopathy is the main cause of LH. This study aimed to determine the relationship between BMI and ICH. MATERIALS AND METHODS: In this retrospective study involving 460 consecutive patients with ICH, BMI was significantly lower in LH than for other ICH locations. BMI categories were underweight (BMI < 18.5 kg/m(2)), normal weight (18.5-23.0 kg/m(2)), overweight (23.0-27.5 kg/m(2)), or obesity (≥27.5 kg/m(2)). Outcome at 1 year was evaluated by the modified Rankin Scale (mRS). We investigated the relationship of BMI and other clinical characteristics with LH and non-LH. RESULTS: LH was associated with age (>70 years), underweight, unfavorable outcome (mRS ≥3), and daily alcohol consumption. Hypertension and intraventricular bleeding were significantly less common in patients with LH than those with non-LH. CONCLUSIONS: Alongside risk factors conventionally thought to be related to LH, underweight may also be a LH-related factor, specifically in the elderly.

Improving the depth resolution of STEM-ADF sectioning by 3D deconvolution.

Although the possibility of locating single atom in three dimensions using the scanning transmission electron microscope (STEM) has been discussed with the advent of aberration correction technology, it is still a big challenge. In this report we have developed deconvolution routines based on maximum entropy method (MEM) and Richardson-Lucy algorithm (RLA), which are applicable to the STEM-annular dark-field (ADF) though-focus images to improve the depth resolution. The new three-dimensional (3D) deconvolution routines require a limited defocus-range of STEM-ADF images that covers a whole sample and some vacuum regions. Since the STEM-ADF probe is infinitely elongated along the optical axis, a 3D convolution is performed with a two-dimensional (2D) convolution over xy-plane using the 2D fast Fourier transform in reciprocal space, and a one-dimensional convolution along the z-direction in real space. Using our new deconvolution routines, we have processed simulated focal series of STEM-ADF images for single Ce dopants embedded in wurtzite-type AlN. Applying the MEM, the Ce peaks are clearly localized along the depth, and the peak width is reduced down to almost one half. We also applied the new deconvolution routines to experimental focal series of STEM-ADF images of a monolayer graphene. The RLA gives smooth and high-P/B ratio scattering distribution, and the graphene layer can be easily detected. Using our deconvolution algorithms, we can determine the depth locations of the heavy dopants and the graphene layer within the precision of 0.1 and 0.2 nm, respectively. Thus, the deconvolution must be extremely useful for the optical sectioning with 3D STEM-ADF images.

Relevance of level IIb neck dissection in patients with papillary thyroid carcinoma.

BACKGROUND: Cervical nodal metastasis is a key prognostic factor in patients with papillary thyroid carcinoma. The role of lymph nodes in papillary thyroid carcinoma management and prognosis remains controversial. METHODS: Level IIb lymph nodes obtained from 44 patients with papillary thyroid carcinoma were histopathologically examined retrospectively. Specimens were classified as ipsilateral or contralateral. The number of dissected nodes and prevalence of level IIb metastasis were compared according to pre-operative clinical nodal stage. RESULTS: In the node-negative neck, the prevalence of contralateral and ipsilateral IIb nodes was 0 out of 20 and 0 out of 3, respectively. In the node-positive neck, the prevalence of contralateral and ipsilateral IIb nodes was 1 out of 13 (7.70 per cent) and 3 out of 41 (7.32 per cent), respectively. Clinically determined and pathologically confirmed level IIb node negativity were significantly associated. Thirty-four patients (77.3 per cent) developed accessory nerve complications from level IIb dissection. CONCLUSION: Level IIb neck dissection for papillary thyroid carcinoma may be required if pre-operative examination reveals multilevel, level IIa or suspicious level IIb metastasis.

Factors limiting quantitative phase retrieval in atomic-resolution differential phase contrast scanning transmission electron microscopy using a segmented detector.

Quantitative differential phase contrast imaging of materials in atomic-resolution scanning transmission electron microscopy using segmented detectors is limited by various factors, including coherent and incoherent aberrations, detector positioning and uniformity, and scan-distortion. By comparing experimental case studies of monolayer and few-layer graphene with image simulations, we explore which parameters require the most precise characterisation for reliable and quantitative interpretation of the reconstructed phases. Coherent and incoherent lens aberrations are found to have the most significant impact. For images over a large field of view, the impact of noise and non-periodic boundary conditions are appreciable, but in this case study have less of an impact than artefacts introduced by beam deflections coupling to beam scanning (imperfect tilt-shift purity).

Large angle illumination enabling accurate structure reconstruction from thick samples in scanning transmission electron microscopy.

Most reconstructions of the electrostatic potential of a specimen at atomic resolution assume a thin and weakly scattering sample, restricting accurate quantification to specimens only tens of Ångströms thick. We demonstrate that using large-angle-illumination scanning transmission electron microscopy (STEM)-a probe forming aperture with convergence angle larger than about 50 mrad-allows us to better meet the weak phase object approximation and thereby accurately reconstruct the electrostatic potential in samples thicker than the order of 100 Å.

A new method to detect and correct sample tilt in scanning transmission electron microscopy bright-field imaging.

Important properties of functional materials, such as ferroelectric shifts and octahedral distortions, are associated with displacements of the positions of lighter atoms in the unit cell. Annular bright-field scanning transmission electron microscopy is a good experimental method for investigating such phenomena due to its ability to image light and heavy atoms simultaneously. To map atomic positions at the required accuracy precise angular alignment of the sample with the microscope optical axis is necessary, since misalignment (tilt) of the specimen contributes to errors in position measurements of lighter elements in annular bright-field imaging. In this paper it is shown that it is possible to detect tilt with the aid of images recorded using a central bright-field detector placed within the inner radius of the annular bright-field detector. For a probe focus near the middle of the specimen the central bright-field image becomes especially sensitive to tilt and we demonstrate experimentally that misalignment can be detected with a precision of less than a milliradian, as we also confirm in simulation. Coma in the probe, an aberration that can be misidentified as tilt of the specimen, is also investigated and it is shown how the effects of coma and tilt can be differentiated. The effects of tilt may be offset to a large extent by shifting the diffraction plane detector an amount equivalent to the specimen tilt and we provide an experimental proof of principle of this using a segmented detector system.

Pharmacokinetics of recombinant human granulocyte colony-stimulating factor conjugated to polyethylene glycol in rats.

The pharmacokinetics of recombinant human granulocyte colony-stimulating factor conjugated to polyethylene glycol (PEG-rhG-CSF) and rhG-CSF were studied in male Sprague-Dawley rats. The serum concentration after i.v. administration at a dose of 100 micrograms protein/kg was investigated by a bioassay. The serum rhG-CSF concentration decreased steadily after injection with a terminal half-life of 1.79 h. The PEG-rhG-CSF concentration after injection decreased much more slowly with a half-life of 7.05 h. The slower disappearance of PEG-rhG-CSF resulted in a greater area under the concentration-time curve. The neutrophil count after 100 micrograms of protein/kg of rhG-CSF administration reached a peak 12 h after injection and returned to the control level 48 h after injection. The neutrophil count after 100 micrograms of protein/kg of PEG-rhG-CSF administration was identical to that of rhG-CSF after 12 h but the highest level was maintained for 24 to 72 h after injection and returned to the control level after 168 h. These data indicated that PEG-rhG-CSF administration exerted a sustained biological effect on peripheral blood neutrophils. It is expected that PEG-rhG-CSF may contribute greatly to human G-CSF treatment because it has a prolonged neutrophil-proliferating activity enabling fewer administrations.

In vitro long-term culture of human primitive hematopoietic cells supported by murine stromal cell line MS-5.

When Lin-CD34+CD38- cells from normal human cord blood were cocultured with MS-5, colony forming cells were maintained for over 8 weeks. Prevention of contact between MS-5 and Lin-CD34+CD38- cells by using a membrane filter was negligible for this activity, indicating that the activity of MS-5 on human primitive hematopoietic cells may be due to soluble factor(s) secreted from MS-5. We tried to purify this activity by a [3H]TdR incorporation assay. The activity was found in 150 kD fraction and was neutralized with anti-mSCF (stem cell factor) antibody. Another 20-30 kD fraction synergized with mSCF to stimulate the growth of Lin-CD34+CD38- cells but failed alone. This fraction supported the growth of the G-CSF (granulocyte-colony stimulating factor)-dependent cell line FD/GR3, FDC-P2 transfected with mG-CSF receptor cDNA. This synergy was canceled in the presence of soluble mG-CSF receptor. Addition of anti-mSCF antibody and soluble mG-CSF receptor to the culture completely abrogated the activity of MS-5-culture supernatant. These results indicate the activity of MS-5 on Lin-CD34+CD38- cells is due to synergistic effect of mSCF and mG-CSF.

Granulocyte-colony stimulating factor and stem cell factor are the crucial factors in long-term culture of human primitive hematopoietic cells supported by a murine stromal cell line.

The findings that murine marrow stromal cell line MS-5 supported the proliferation of human lineage-negative (Lin-) CD34+CD38- bone marrow cells in long-term culture have been reported. In this study, we analyzed this proliferating activity of MS-5-conditioned medium (CM) on human primitive hematopoietic cells. When Lin-CD34+CD38- cells of normal human cord blood cells were co-cultured with MS-5, colony forming cells (CFCs) were maintained over 7 weeks in vitro. Prevention of contact between MS-5 and Lin-CD34+CD38- cells by using membrane filter (0.45 micron) was negligible for this activity. This indicated that the activity of MS-5 on human primitive hematopoietic cells is a soluble factor(s) secreted from MS-5, which is not induced by the contact between MS-5 and Lin-CD34+CD38- cells. We tried to purify this soluble activity. An active material with a molecular weight of about 150 kDa, determined by gel filtration chromatography, solely supported the growth of Lin-CD34+CD38- cells and Mo7e, a human megakaryocytic cell line. This activity not only reacted with anti-mouse stem cell factor (mSCF) antibody on Western blots, but it was also neutralized in the presence of anti-mSCF antibody. Another active material with a molecular weight of about 20-30 kDa synergized with mSCF to stimulate the growth of Lin-CD34+CD38- cells but failed to do so alone, although this synergy was inhibited in the presence of soluble mouse granulocyte-colony stimulating factor (mG-CSF) receptor, which is a chimeric protein consisting of the extracellular domain of mG-CSF receptor and the Fe region of human IgG1. In addition, the latter molecule supported the growth of the G-CSF dependent cell line FD/GR3, which is a murine myeloid leukemia cell line, FDC-P2, transfected with mG-CSF receptor cDNA. Adding of anti-mSCF antibody and soluble mG-CSF receptor to the culture completely abrogated the activity of MS-5-CM. Recombinant (r) mSCF and rmG-CSF had synergistic activity on the growth of Lin-CD34+CD38- cells. These results indicated that the activity on Lin-CD34+CD38- cells included in MS-5-CM is based upon the synergistic effects of mSCF and mG-CSF.

Inhibitory Ca(2+)-regulation of myosin light chain kinase in the lower eukaryote, Physarum polycephalum: role of a Ca(2+)-dependent inhibitory factor.

ATP-dependent interactions between myosin and actin in the lower eukaryote, Physarum polycephalum, are inhibited by micromolar levels of Ca2+. This inhibition is mediated by the binding of Ca2+ to myosin, the phosphorylation of which is required if Ca2+ is to inhibit the activities of myosin (Kohama, K., Trends Pharmacol. Sci. 11, 433-435 (1990)). As the first step to examine whether Ca2+ also regulates phosphorylation in the actomyosin system, we purified myosin light chain kinase (MLCK) of 55 kDa almost to homogeneity. The MLCK activity was high whether or not Ca2+ was present. However, a Ca(2+)-dependent inhibitory factor (CIF) purified from Physarum (Okagaki et al., Biochem. Biophys. Res. Commun. 176, 564-570 (1991)) was shown to reduce the MLCK activity in a Ca(2+)-dependent manner. Using crude preparations, not only MLCK but also myosin heavy chain kinase and actin kinase were shown to be inhibited by Ca2+ half-maximally at micromolar levels. Since CIF is the only Ca(2+)-binding protein in the preparations, we propose that this inhibitory Ca(2+)-regulation of the kinases for actomyosin is mediated by CIF.

The binding of nonmuscle caldesmon from brain to microtubules. Regulations by Ca(2+)-calmodulin and cdc2 kinase.

Nonmuscle caldesmon from bovine brain bound to microtubules with a stoichiometry of five tubulin dimers to one molecule of caldesmon with values of Ka 4.5 x 10(5) M-1. The binding of caldesmon to microtubules was inhibited in the presence of Ca2+ and calmodulin. The phosphorylation of caldesmon by cdc2 kinase also eliminated the microtubule-binding activity. These results suggest that caldesmon may play a physiological role in the functions of microtubules.

The fastest actin-based motor protein from the green algae, Chara, and its distinct mode of interaction with actin.

The endoplasmic streaming in Characean cells is an actin-dependent movement. The motor protein responsible for the streaming was partially purified and characterized. It was soluble at low ionic strength, an ATPase of a molecular mass of 225 kDa and activated more than 100 times by muscle F-actin. Surprisingly, in an in vitro motility assay, the motor protein moved muscle F-actin at 60 microns/s, which is similar to the velocity of streaming in a living cell and 10 times faster than muscle myosin. Proteolytic cleavage of actin impaired movement crucially on muscle myosin, but did not affect movement at all on the Chara motor protein, suggesting that the Chara motor protein would interact with actin via a set of sites different from those of muscle myosin.

Calvasculin, as a factor affecting the microfilament assemblies in rat fibroblasts transfected by src gene.

Cell transformations accompany alterations in cell morphology and microfilament patterns. Calvasculin encodes mRNA termed pEL-98, 18A2, 42A, p9Ka, or mts1, found to be elevated in several metastatic cell lines. We report the elevation of calvasculin expression in SR-3Y1 cells, which show disappearance of ordered microfilaments, compared to that in 3Y1 cells and that the similar distribution of calvasculin to that of actin filaments. Interestingly, calvasculin co-sediments with F-actin and bundles actin filaments in a Ca(2+)-dependent manner. This activity, along with the elevation of calvasculin following transformation, suggests that the disorganization of filaments in SR-3Y1 cell is due to the cross-linking activity of calvasculin.

The ocular hypertensive response following experimental acid burns in the rabbit eye.

Following application of 50 microliter of 2N hydrochloric acid to the rabbit cornea, the intraocular pressure rapidly increases and remains markedly elevated for up to 3 hr. The initial rapid increase in intraocular pressure appears to be the result of acid-induced shrinkage of the outer collagenous coats of the eye. The sustained rise in intraocular pressure is mediated in part by prostaglandin release. Increased prostaglandin-like activity, determined in the aqueous after an acid burn, was greatly inhibited by pretreatment of rabbits with indomethacin and to a much lesser extent by pretreatment with imidazole. Both indomethacin and imidazole essentially abolished the sustained elevation of intraocular pressure after an acid burn. Analysis of changes in pH and protein level in the aqueous implies that the stimulus for prostaglanding release within the eye is the penetration of hydrogen ions into the aqueous humor, with resultant intraocular trauma.

Retinal fascin: functional nature, subcellular distribution, and chromosomal localization.

PURPOSE: To investigate the functional properties, subcellular localization, and chromosomal location of retinal fascin. METHODS: Recombinant retinal fascin protein was prepared by using a baculovirus-insect expression system. Actin-binding and -bundling assays were performed with chick actin purified from skeletal muscle. Western blot analysis and immunohistochemistry were performed with a polyclonal antibody raised against bovine retinal fascin. A human retinal cDNA library was screened with an expressed sequence tag cDNA fragment. Chromosomal location was determined with fluorescent in situ hybridization. RESULTS: The actin-binding and actin-bundling activities of retinal fascin were demonstrated by high- and low-speed centrifugation assays. Formation of filamentous (F)-actin bundles by retinal fascin in vitro was also morphologically confirmed by fluorescence microscopy and electron microscopy. Immunohistochemical analysis revealed that retinal fascin protein was localized specifically in the outer and inner segments of the photoreceptor cells in the retina. Two splicing variants of human retinal fascin cDNA were also located. One clone encoded 492 amino acids, and the other encoded 516 amino acids. The gene encoding retinal fascin was localized to human chromosome 17, region q24 -25. CONCLUSIONS: These results suggest that retinal fascin may play a role in formation of unique morphologic structures of the photoreceptor cells and is a candidate gene for retinal degenerative disorders.

Sex hormone modulation of interferon (IFN) alpha/beta and gamma production by mouse spleen cell subsets following picornavirus infection.

Replication of the diabetogenic variant of encephalomyocarditis virus (EMCV-D) in spleen cells and its association with subpopulations of spleen cells (L3T4+, Lyt-2+, Mac 1+, 33D1+ and AGM1+ cells) from both sexes of ICR Swiss mice were examined. Virus replication was limited to less than 0.5 log in suspensions of whole spleen cells, nonadherent cells or a B cell subfraction from both sexes of ICR Swiss mice following infection with EMCV-D at an MOI of 10; no virus replication was seen in adherent spleen cells from either sex. After 1 hour adsorption of EMCV-D onto spleen cells at a multiplicity of infection (MOI) of either 10 or 0.1, virus-associated cells were isolated using a monoclonal murine anti-EMCV-D and anti-mouse IgG conjugated to magnetic beads. Using an MOI of 0.1, less than 1% of spleen cells bound virus particles after 1 hour adsorption at 4 degrees C. Among the virus-positive cells, relatively higher percentages of adherent cell populations (Mac 1+ and 33D1+ cells) of both sexes bound virus particles within the first hour post-infection (PI) than did the other spleen cell subpopulations. Interferon (IFN) alpha/beta production was detected as early as 4 hours PI in female spleen cell cultures infected with EMCV-D at an MOI of 0.1 while no IFN alpha/beta activity was found in comparably infected male spleen cell cultures. Inhibiting IFN alpha/beta activity in the virus-infected spleen cell cultures during the first 20 hours of infection using polyclonal rabbit anti-mouse IFN alpha/beta serum eliminated production of IFN gamma as well as IFN alpha/beta. Spleen cell cultures depleted of adherent cells were unable to produce IFN alpha/beta or IFN gamma in the first 24 hours PI. The capacity to produce IFN gamma at 12 hours after virus infection of spleen cells from both sexes of mice was restored to adherent cell-depleted cultures by addition of mouse IFN alpha/beta at the time of infection. These results suggest that IFN alpha/beta and adherent cells play critical roles in the early production of IFN gamma (less than 16 hours PI) characteristic of the infected spleen cell cultures of females. Production of IFN alpha/beta and IFN gamma by spleen cells from both sexes of ICR Swiss mice was enhanced by administrating estrone to donor mice during the week before harvesting spleen cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Role of myosin in the stimulatory effect of caldesmon on the interaction between actin, myosin, and ATP.

We have previously shown that caldesmon at low concentrations stimulates the interaction between actin, myosin, and ATP, while at high concentrations it inhibits the interaction [Ishikawa, R., Okagaki, T., Higashi-Fujime, S., & Kohama, K. (1991) J. Biol. Chem. 266, 21784-21790]. When the effect of caldesmon at low concentrations was monitored by measuring myosin ATPase activity in the absence of actin, the effect was slightly but significantly stimulatory; and at higher concentrations no inhibitory effect was observed. Therefore, we related the stimulatory effect with the myosin-binding property of caldesmon. In the presence of actin, a low concentration of caldesmon was not enough to evince the stimulatory effect: myosin concentration must also be low. This is because the stimulatory effect was obscured when myosin concentration was elevated. Ca(2+)-calmodulin abolished the stimulatory effect of caldesmon. However, the concentration of calmodulin required to abolish the stimulation was higher than that required to abolish the inhibition.

Stimulatory effect of calponin on myosin ATPase activity.

Calponin, a calmodulin-binding protein of smooth muscle that inhibits the actin-myosin interaction by binding to actin, was shown to bind to myosin and to stimulate the ATPase activity of myosin to some extent. Actin abolished this myosin-linked, stimulatory effect of calponin. Ca(2+)-calmodulin affected neither the myosin-binding activity nor the stimulatory effect of calponin. We further presented a few data which suggest that calponin may exert regulatory activity toward myosin in quite a different way from caldesmon, another smooth muscle protein that binds to myosin, actin, and calmodulin.