Observation of the 3n evaporation channel in the complete hot-fusion reaction 26Mg + 248Cm leading to the new superheavy nuclide 271Hs

The analysis of a large body of heavy ion fusion reaction data with medium-heavy projectiles (6 < or = Z < or = 18) and actinide targets suggests a disappearance of the 3n exit channel with increasing atomic number of the projectile. Here, we report a measurement of the excitation function of the reaction (248)Cm ((26)Mg,xn)(274-x)Hs and the observation of the new nuclide (271)Hs produced in the 3n evaporation channel at a beam energy well below the Bass fusion barrier with a cross section comparable to the maxima of the 4n and 5n channels. This indicates the possible discovery of new neutron-rich transactinide nuclei using relatively light heavy ion beams of the most neutron-rich stable isotopes and actinide targets.

The absence of physical-aging effects on the surface relaxations of rubbed polystyrene

Extensive experimental results are presented to reveal the relaxations of polystyrene surface deformed by rubbing with a velvet cloth. We found that surface topographic features, such as ditches and ridges created by rubbing, relax at temperatures at about 20( degrees ) C below the bulk glass transition temperature of the polystyrene for a molecular weight of 442 kg/mol, even though we estimate the Laplace Pressure driving the relaxation to be 1/500 of the yield limit. The relaxation is independent of the thermal history before the rubbing process, and post rubbing thermal history below 55( degrees ) C . In other words, physical-aging processes at 23( degrees ) C for up to 7 days and at 50( degrees ) C for 2 days, which would have drastic effects on the relaxations of bulk polymers, have little effects on the relaxations of rubbed surfaces. This is consistent with the mobility enhancement in the surface layer previously reported in the literature.

Hyperbaric oxygen for experimental intracerebral hemorrhage

Acute brain edema formation contributes to brain injury after intracerebral hemorrhage (ICH). It has been reported that hyperbaric oxygen (HBO) is neuroprotective in cerebral ischemia, subarachnoid hemorrhage, and brain trauma. In this study, we investigated the effects of HBO on brain edema following ICH in rats. Male Sprague-Dawley rats received intracerebral infusion of autologous whole blood, thrombin, or ferrous iron. HBO (100% O2, 3.0 ATA for 1 h) was initiated 1 h after intracerebral injection. Control rats were exposed to air at room pressure. Brains were sampled at 24 or 72 h for water content, ion measurement, and Western blot analysis. We found that 1 session of HBO reduced perihematomal brain edema (p < 0.05) 24 h after ICH. HBO also reduced heat shock protein-32 (HSP-32) levels (p < 0.05) in ipsilateral basal ganglia 24h after ICH. However, HBO failed to attenuate thrombin-induced brain edema and exaggerated ferrous iron-induced brain edema (p < 0.05). Three sessions of HBO also failed to reduce brain edema 72h after ICH. In summary, HBO reduced early perihematomal brain edema and HSP-32 levels in brain. HBO-related brain protection does not occur through reduction in thrombin toxicity because HBO failed to attenuate thrombin-induced brain edema. Our results also indicate that HBO treatment after hematoma lysis for ICH may be harmful, since HBO amplifies iron-induced brain edema.

Doubly magic nucleus (108)(270)Hs162

Theoretical calculations predict 270Hs (Z=108, N=162) to be a doubly magic deformed nucleus, decaying mainly by alpha-particle emission. In this work, based on a rapid chemical isolation of Hs isotopes produced in the 26Mg+248Cm reaction, we observed 15 genetically linked nuclear decay chains. Four chains were attributed to the new nuclide 270Hs, which decays by alpha-particle emission with Qalpha=9.02+/-0.03 MeV to 266Sg which undergoes spontaneous fission with a half-life of 444(-148)(+444) ms. A production cross section of about 3 pb was measured for 270Hs. Thus, 270Hs is the first nucleus for which experimental nuclear decay properties have become available for comparison with theoretical predictions of the N=162 shell stability.

Chemical investigation of hassium (element 108)

The periodic table provides a classification of the chemical properties of the elements. But for the heaviest elements, the transactinides, this role of the periodic table reaches its limits because increasingly strong relativistic effects on the valence electron shells can induce deviations from known trends in chemical properties. In the case of the first two transactinides, elements 104 and 105, relativistic effects do indeed influence their chemical properties, whereas elements 106 and 107 both behave as expected from their position within the periodic table. Here we report the chemical separation and characterization of only seven detected atoms of element 108 (hassium, Hs), which were generated as isotopes (269)Hs (refs 8, 9) and (270)Hs (ref. 10) in the fusion reaction between (26)Mg and (248)Cm. The hassium atoms are immediately oxidized to a highly volatile oxide, presumably HsO(4), for which we determine an enthalpy of adsorption on our detector surface that is comparable to the adsorption enthalpy determined under identical conditions for the osmium oxide OsO(4). These results provide evidence that the chemical properties of hassium and its lighter homologue osmium are similar, thus confirming that hassium exhibits properties as expected from its position in group 8 of the periodic table.

Macrophage-derived chemokine gene transfer results in tumor regression in murine lung carcinoma model through efficient induction of antitumor immunity

Chemokine gene transfer represents a promising approach in the treatment of malignancies. Macrophage-derived chemokine (MDC) (CCL22) belongs to the CC chemokine family and is a strong chemoattractant for dendritic cells (DC), NK cells and T cells. Using adenoviral vectors, human MDC gene was transferred in vivo to investigate its efficacy to induce an antitumor response and to determine the immunologic mechanisms involved. We observed that intratumoral injection of recombinant adenovirus encoding human MDC (AdMDC) resulted in marked tumor regression in a murine model with pre-established subcutaneous 3LL lung carcinoma and induced significant CTL activity. The antitumor response was demonstrated to be CD4+ T cell- and CD8+ T cell-dependent. Administration of AdMDC induced chemoattraction of DC to the tumor site, facilitated DC migration to draining lymph nodes or spleen, and finally activated DC to produce high levels of IL-12. Furthermore, a significant increase of IL-4 production within the tumors was observed early after the AdMDC administration and was followed by the increase of IL-12 and IL-2 production. The levels of IL-2, IL-12 and IFN-gamma in serum, lymph nodes and spleen were also found to be higher in mice treated with AdMDC as compared with that in AdLacZ- or PBS-treated mice. The antitumor response induced by AdMDC was markedly impaired in IL-4 knockout mice, suggesting an important role of IL-4 in the induction of antitumor immunity by MDC. These results suggest that MDC gene transfer might elicit significant antitumor effects through efficient induction of antitumor immunity and might be of therapeutic potentials for cancer.

Tumor rejection by disturbing tumor stroma cell interactions

The stroma of solid tumors is a complex network of different cell types. We analyzed stroma cell interactions in two tumor models during cyclophosphamide (Cy)-induced tumor rejection. In growing tumors, tumor infiltrating macrophages (TIMs) produced interleukin (IL)-10. Beginning 6 h after Cy-treatment T cells in the tumor were inactivated and TIMs switched to interferon (IFN)-gamma production. Both, IL-10 production before and IFN-gamma production after Cy-treatment by TIMs required T cells. With the same kinetics as TIMs started to produce IFN-gamma the tumor vasculature was destroyed which required IFN-gamma receptor expression on host but not tumor cells. These events preceded hemorrhagic necrosis and residual tumor cell elimination by T cells. Together, T cells regulate the function of TIMs and tumor rejection can be induced by disturbing the stroma network.

Self-assembly of polymer and sheet structures from palladium(II) complexes by hydrogen bonding between carboxamide substituents

The self-assembly of supramolecular structures from either neutral or cationic palladium(II) complexes containing primary or secondary carboxamide groups as substituents on pyridine ligands has been explored. The displacement of PhCN in trans-[PdCl(2)(PhCN)(2)] by L = N-methylnicotinamide (MNA), isonicotinamide (INA), or nicotinamide (NA) gave the corresponding complexes trans-[PdCl(2)L(2)] 1-3, respectively. Complex 1.H(2)O forms a 2D sheet network via amide-amide hydrogen bonding supported by chloride ligand-to-water hydrogen-bonding interactions. Several cationic complexes, [Pd(L'L')L(2)](2+) 4-9 and 11-16, containing the above ligands and with PPh(3), dppp, dppm, or bu(2)bipy as ancillary ligand(s) were prepared. Complex 4 (L = MNA, L'L' = dppp) forms dimers through amide-amide hydrogen bonding, forming macrocycles which further propagate to form chains via weak C-H...O=C hydrogen bonding. Complex 6 (L = NA, L'L' = dppp) forms zigzag chains connected by amide head-to-head hydrogen bonds. Complex 8 (L = INA, L'L' = dppm) gives interesting double-stranded ribbons linked by two types of amide--amide hydrogen-bonding interactions. Complex 13 (L' = PPh(3), L = NA) forms an infinite chain via complementary amide-amide hydrogen bonds. Complex 14 (L = MNA, L'L' = bu(2)bipy) forms infinite ribbons via the combination of amide hydrogen bonding mediated by a BF(4) anion and weak C-H...O=C hydrogen bonding. Complex 15 (L = INA, L'L' = bu(2)bipy) gives a ladder polymer formed through amide--amide hydrogen bonds. The structure of cis-[Pd(PPh(3))(2)(OH(2))(2)] (OTf)(2) (10) is also reported.

Refolding of beta-lactoglobulin studied by stopped-flow circular dichroism at subzero temperatures

Refolding of bovine beta-lactoglobulin was studied by stopped-flow circular dichroism at subzero temperatures. In ethylene glycol 45%-buffer 55% at -15 degrees C, the isomerization rate from the kinetic intermediate rich in alpha-helix to the native state is approximately 300-fold slower than that at 4 degrees C in the absence of ethylene glycol, whereas the initial folding is completed within the dead time of the stopped-flow apparatus (10 ms). At -28 degrees C, we observed at least three phases; the fastest process, accompanied by an increase of alpha-helix content, is completed within the dead time of the stopped-flow apparatus (10 ms), the second phase, accompanied by an increase of alpha-helix content with the rate of 2 s(-1), and the third phase, accompanied by a decrease of alpha-helix content. This last phase, corresponding to the isomerization process at -15 degrees C described above, was so slow that we could not monitor any changes within 4 h. Based on the findings above, we propose that rapid alpha-helix formation and their concurrent collapse are common even in proteins rich in beta-structure in their native forms.

Calcium-dependent stabilization of the central sequence between Met(76) and Ser(81) in vertebrate calmodulin

Spin-label electron paramagnetic resonance (EPR) provides optimal resolution of dynamic and conformational heterogeneity on the nanosecond time-scale and was used to assess the structure of the sequence between Met(76) and Ser(81) in vertebrate calmodulin (CaM). Previous fluorescence resonance energy transfer and anisotropy measurements indicate that the opposing domains of CaM are structurally coupled and the interconnecting central sequence adopts conformationally distinct structures in the apo-form and following calcium activation. In contrast, NMR data suggest that the opposing domains of CaM undergo independent rotational dynamics and that the sequence between Met(76) and Ser(81) in the central sequence functions as a flexible linker that connects two structurally independent domains. However, these latter measurements also resolve weak internuclear interactions that suggest the formation of transient helical structures that are stable on the nanosecond time-scale within the sequence between Met(76) and Asp(80) in apo-CaM (H. Kuboniwa, N. Tjandra, S. Grzekiek, H. Ren, C. B. Klee, and A. Bax, 1995, Nat. Struct. Biol. 2:768-776). This reported conformational heterogeneity was resolved using site-directed mutagenesis and spin-label EPR, which detects two component spectra for 1-oxyl-2,2,5,5-tetramethylpyrroline-3-methyl)-methanethiosulfonate spin labels (MTSSL) bound to CaM mutants T79C and S81C that include a motionally restricted component. In comparison to MTSSL bound within stable helical regions, the fractional contribution of the immobilized component at these positions is enhanced upon the addition of small amounts of the helicogenic solvent trifluoroethanol (TFE). These results suggest that the immobilized component reflects the formation of stable secondary structures. Similar spectral changes are observed upon calcium activation, suggesting a calcium-dependent stabilization of the secondary structure. No corresponding changes are observed in either the solvent accessibility to molecular oxygen or the maximal hyperfine splitting. In contrast, more complex spectral changes in the line-shape and maximal hyperfine splitting are observed for spin labels bound to sites that undergo tertiary contact interactions. These results suggest that spin labels at solvent-exposed positions within the central sequence are primarily sensitive to backbone fluctuations and that either TFE or calcium binding stabilizes the secondary structure of the sequence between Met(76) and Ser(81) and modulates the structural coupling between the opposing domains of CaM.

[The effects of Ag+ on the absorption of trace metal ion during the somatic embryogenesis of Lycium barbarum. L]

We used callus of medical plant, Ningxia Lycium barbarum. L as material to induce somatic embryo genesis, and used multitracer technique and gamma-ray energy spectrum analytical method to study different concentration of AgNO3 on some absorption of trace metal ions during the somatic embryogenesis of Lycium barbarum. L. The results show that (1) when the concentration of AgNO3 is less then 50 mg/L, with the increase of AgNO3 concentration, the absorption rate of some metal ions is increasing, but when the concentration is excess of such concentration, the effects on the absorption rate are different. Ag+ has the effect of coordination, resistance or competition on the absorption of metal ions. (2) AgNO3 in suitable concentration will promote cell differentiation and somatic embryogenesis. When the concentration of AgNO3 is less then 50 mg/L, along with the increase of the concentration, the frequency of somatic embryogenesis is increased, and Ag+ has the promotion on the somatic embryogenesis of Lycium barbarum. L. While the concentration is up to 50 mg/L, it will mostly raise somatic embryogenesis in calli, the amount of callus is about 3 times as much as that of contrast group (in which AgNO3 is not added). When excess of this concentration point, Ag+ has toxic effect, and the somatic embryogenesis is inhibited remarkably.

Decreased generation of anti-tumor immunity after intrasplenic immunization

The localization of antigen and the nature of the host antigen-presenting cells (APC) that present it to T cells are two major determinants of antigen immunogenicity. While lymph nodes appear to be the major site for T cell priming, recently the spleen was shown to provide an optimal microenvironment for direct CD8+ cytotoxic T cell (CTL) priming by tumor cells even in the absence of known costimulatory molecules on tumor cells. We analyzed whether the splenic microenvironment would support T cell priming also when host APC are involved (cross-priming) which is probably the major pathway during the generation of anti-tumor immunity. We performed immunization/challenge experiments using different tumor cells (B7.1+, B7.1- and/or beta-gal+, beta-gal-) known to induce CTL to a variable extent either exclusively by cross-priming (B7-) or at least partially by direct priming (B7+). Our results demonstrate that tumor take in the spleen required much less cells than at a subcutaneous injection site. Additionally, intrasplenic immunization was invariably ineffective compared to subcutaneous immunization. We further showed that B cells were not responsible for the inefficient intrasplenic immunization. Therefore delivering the tumor cell antigens inside the spleen by intrasplenic immunization did not improve but rather decreased the efficacy of tumor cell vaccines.

[Expression of BDNF and FGF-2 following axotomy in rat facial motoneurons]

OBJECTIVE

To study the expression and distribution of brain derived neurotrophic factor (BDNF) and fibroblast growth factor-2 (FGF-2) in normal facial motoneurons (FMNs) and in FMNs following axotomy.

METHODS

The right facial nerves were transected 6 mm distal to the stylomastoid foraman in adult Wistar rats except the normal group. Serial 20 microns cryosections were cut through the whole brainstems. Expressions of BDNF and FGF-2 mRNA as well as BDNF and FGF-2 protein were studied by in situ hybridization, immunohistochemistry and image analysis.

RESULTS

BDNF mRNA and its protein were observed in widespread areas of normal rat facial nucleus, and those increased 1 day after axotomy. In addition to neurons, glial cells were also stained. FGF-2 mRNA and its protein were mainly localized in normal FMNs of ventral facial nucleus. After axotomy, expression of FGF-2 mRNA started to up-regulate in FMNs at 7 days, however FGF-2 protein drastically reduced at 3 and 7 days.

CONCLUSION

In addition to target-supporting, there may be BDNF autocrine and paracrine mechanisms as well as FGF-2 autocrine mechanisms in normal rat FMN. When target-derived BDNF is deprived, alternative sources of BDNF support may substitute immediately after axotomy. However, deprivating of target--derived FGF-2 may result in down-regulation of FGF-2 protein in adult rat FMNs at early stage after axotomy. These suggest that the exogenous FGF-2 might provide a supportive environment for the recovery of metabolism and function of FMNs at early stage following axotomy.

[Maxillofacial vascular malformation associated with abnormal communication between external carotid and cranial arteries]

OBJECTIVE

To introduce the clinical characteristics of maxillofacial vascular malformation with abnormal communication between external carotid and cranial arteries.

METHODS

One hundred and twenty patients with maxillofacial vascular malformations had been studied by arteriography of internal and external carotid, and vertebral arteries before embolization of tumor supplying artery. Cases found to have communications between extra- and intra-cranial arteries were analyzed.

RESULTS

Fourteen patients (11.67%, 14/120) were found to have abnormal communications between external carotid and cranial arteries. Among them, 11 patients demonstrated communications between occipital and vertebral arteries, 1 patient showed ascending pharyngeal artery and vertebral artery communication, and 2 patients showed maxillary artery-ophthalmic artery communication.

CONCLUSION

Embolization of tumor supplying artery is a safe and practical method for the treatment of maxillofacial vascular malformation when done under digital subtraction angiography and superselective catheterization to avoid the abnormal communicant branches.

Assessment of arterial stenosis in a flow model with power Doppler angiography: accuracy and observations on blood echogenicity

The objective of the project was to study the influence of various hemodynamic and rheologic factors on the accuracy of 3-D power Doppler angiography (PDA) for quantifying the percentage of area reduction of a stenotic artery along its longitudinal axis. The study was performed with a 3-D power Doppler ultrasound (US) imaging system and an in vitro mock flow model containing a simulated artery with a stenosis of 80% area reduction. Measurements were performed under steady and pulsatile flow conditions by circulating, at different flow rates, four types of fluid (porcine whole blood, porcine whole blood with a US contrast agent, porcine blood cell suspension and porcine blood cell suspension with a US contrast agent). A total of 120 measurements were performed. Computational simulations of the fluid dynamics in the vicinity of the axisymmetrical stenosis were performed with finite-element modeling (FEM) to locate and identify the PDA signal loss due to the wall filter of the US instrument. The performance of three segmentation algorithms used to delineate the vessel lumen on the PDA images was assessed and compared. It is shown that the type of fluid flowing in the phantom affects the echoicity of PDA images and the accuracy of the segmentation algorithms. The type of flow (steady or pulsatile) and the flow rate can also influence the PDA image accuracy, whereas the use of US contrast agent has no significant effect. For the conditions that would correspond to a US scan of a common femoral artery (whole blood flowing at a mean pulsatile flow rate of 450 mL min(-1)), the errors in the percentages of area reduction were 4.3 +/- 1.2% before the stenosis, -2.0 +/- 1.0% in the stenosis, 11.5 +/- 3.1% in the recirculation zone, and 2.8 +/- 1.7% after the stenosis, respectively. Based on the simulated blood flow patterns obtained with FEM, the lower accuracy in the recirculation zone can be attributed to the effect of the wall filter that removes low flow velocities. In conclusion, the small errors reported in vitro may support the clinical use of this technique.

A review of therapeutic potentials in ischemic stroke

Stroke is one of the leading causes of death in the world. There are as yet no effective treatments for the ischemic cerebral lesion itself. Nevertheless, five potential therapeutic objectives can be identified. For cerebral infarction, the best treatment is prevention, including targeted preventive treatments for specific subsets of patients or individuals with different risk factors. Incidence rates and mortality rates of stroke have been successfully reduced in certain developed countries by adoption of a public health approach to the prevention and control of risk factors. To rescue the still viable but injured nerve cells, within the ischemic penumbra, effective therapy should be begun at the earliest possible time. Measures to halt or reverse programmed cell death, to enhance the intrinsic autoprotective and repair mechanisms, are under active study. The existence of down-regulated brain regions, where normal nerve cells have far less activities to perform due to interruption of information exchange with the infarct area, and the possibility to reactivate them are worthy of attention.

A caspase-3-like protease is involved in NF-kappaB activation induced by stimulation of N-methyl-D-aspartate receptors in rat striatum

Glutamate receptor stimulation reportedly activates NF-kappaB in vitro and in vivo, although underlying mechanisms remain to be elucidated. Here we evaluated the role of proteases in mediating N-methyl-D-aspartate (NMDA) receptor agonist-induced NF-kappaB activation and apoptosis in rat striatum. The intrastriatal infusion of quinolinic acid (QA, 60 nmol) had no effect on levels of NF-kappaB family proteins, including p65, p50, p52, c-Rel and Rel B. In contrast, QA decreased IkappaB-alpha protein levels by 60% (P<0. 05); other members of the IkappaB family, including IkappaB-beta, IkappaB-gamma, IkappaB-epsilon and Bcl-3, were not altered. The QA-stimulated degradation of IkappaB-alpha was completely blocked by the NMDA receptor antagonist MK-801. QA-induced IkappaB-alpha degradation and NF-kappaB activation were not affected by the proteasome inhibitor MG-132 (1-4 microg). On the other hand, the caspase-3 inhibitor Ac-DEVD.CHO (2-8 microgram) blocked QA-induced IkappaB-alpha degradation in a dose-dependent manner (P<0.05). Ac-DEVD.CHO (4 microgram) also substantially reduced QA-induced NF-kappaB activation (P<0.05), but had no effect on QA-induced AP-1 activation. Furthermore, Ac-DEVD.CHO, but not MG-132, dose-dependently attenuated QA-induced internucleosomal DNA fragmentation. These findings suggest that NF-kappaB activation by NMDA receptor stimulation involves IkappaB-alpha degradation by a caspase-3-like cysteine protease dependent mechanism. Caspase-3 thus appears to contribute to the excitotoxin-induced apoptosis in rat striatal neurons occurring at least partially as a consequence of NF-kappaB activation.