Dark matter results from 100 live days of XENON100 data

We present results from the direct search for dark matter with the XENON100 detector, installed underground at the Laboratori Nazionali del Gran Sasso of INFN, Italy. XENON100 is a two-phase time-projection chamber with a 62 kg liquid xenon target. Interaction vertex reconstruction in three dimensions with millimeter precision allows the selection of only the innermost 48 kg as the ultralow background fiducial target. In 100.9 live days of data, acquired between January and June 2010, no evidence for dark matter is found. Three candidate events were observed in the signal region with an expected background of (1.8 ± 0.6) events. This leads to the most stringent limit on dark matter interactions today, excluding spin-independent elastic weakly interacting massive particle (WIMP) nucleon scattering cross sections above 7.0 × 10(-45) cm(2) for a WIMP mass of 50 GeV/c(2) at 90% confidence level.

A meta-analysis of the relation of polymorphism at sites -1082 and -592 of the IL-10 gene promoter with susceptibility and clearance to persistent hepatitis B virus infection in the Chinese population

BACKGROUND

Up to now, many publications about the Chinese population have evaluated the correlation between interleukin-10 (IL-10) -1082 and -592 polymorphisms and persistent hepatitis B virus (HBV) infection. However, the results remain inconclusive. In order to resolve this conflict, a meta-analysis was performed.

METHODS

Seven studies were included and dichotomous data are presented as the odds ratio (OR) with a 95% confidence interval (CI).

RESULTS

The results of our study suggest that carriers of the IL-10 -592A allele were more likely to clear HBV spontaneously in the Chinese pooled population (A vs. C: OR = 0.799, 95% CI = 0.678-0.941, P = 0.007; AC vs. AA: OR = 1.343, 95% CI = 1.017-1.684, P = 0.011; AA vs. AC + CC: OR = 0.736, 95% CI = 0.594-0.912; AA + AC vs. CC: OR = 0.588, 95% CI = 0.408-0.848, P = 0.004) and the IL-10 -1082A allele was associated with significantly reduced persistent HBV infection risk in Chinese (A vs. G: OR = 0.701, 95% CI = 0.494-0.996, P = 0.047; AA vs. GG + GA: OR = 0.684, 95% CI = 0.476-0.982, P = 0.040).

CONCLUSIONS

Persistent HBV infection susceptibility is associated with the gene polymorphism IL-10 -1082GA in the Chinese population and the clearance of HBV is associated with the gene polymorphism IL-10 -592CA in the Chinese population.

First dark matter results from the XENON100 experiment

The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso in Italy, is designed to search for dark matter weakly interacting massive particles (WIMPs) scattering off 62 kg of liquid xenon in an ultralow background dual-phase time projection chamber. In this Letter, we present first dark matter results from the analysis of 11.17 live days of nonblind data, acquired in October and November 2009. In the selected fiducial target of 40 kg, and within the predefined signal region, we observe no events and hence exclude spin-independent WIMP-nucleon elastic scattering cross sections above 3.4 × 10⁻⁴⁴  cm² for 55  GeV/c² WIMPs at 90% confidence level. Below 20  GeV/c², this result constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.

Distinct molecular signatures in pediatric infratentorial glioblastomas defined by aCGH

Glioblastomas (GBM) are rare in children, but reportedly have more varied outcome which suggests differences in tumor etiology compared to typical GBM of adults. To investigate this we performed high resolution array comparative genomic hybridization (aCGH) analysis on three pediatric infratentorial GBM, ages 3.5, 7 and 14 years. Two of these tumors occurred in the brainstem and one in the spinal cord. While histologically typical, one brainstem tumor showed mainly pleomorphic astrocytic cells, whereas the other brainstem and spinal tumors showed a GFAP positive small cell component. Whole chromosomal gains (#1 and #2) and loss (#20) were seen only in the pleomorphic brainstem GBM, which also showed a high level of segmental genomic copy number changes. Segmental loss involving chromosome 8 was seen in all three tumors (Chr8;133039446-136869494, Chr8;pter-3581577, and Chr8;pter-30480019 respectively), whereas loss involving chromosome 16 was seen in only 2 cases with small cell components (Chr16;31827239-qter and Chr16;pter-29754532). Segmental gain of chromosome 7 was shared only between the 2 brainstem cases (Chr7;17187166-qter and Chr7;69824947-qter). Chromosome 17 showed segmental gain of 17q in the backdrop of loss of 17p only in case 1. Segmental gain of chromosome 1q was seen only in case 2. The spinal GBM showed a relatively stable karyotype with a unique loss of Chr19;32848902-qter. None of the frequent losses, gains and amplifications known to occur in adult GBM were identified, suggesting that pediatric infratentorial glioblastomas show a molecular karyotype that was more characteristic of pediatric embryonal tumors than adult GBM.

The Linear Thermal Expansion of Bulk Nanocrystalline Ingot Iron from Liquid Nitrogen to 300 K

The linear thermal expansions (LTE) of bulk nanocrystalline ingot iron (BNII) at six directions on rolling plane and conventional polycrystalline ingot iron (CPII) at one direction were measured from liquid nitrogen temperature to 300 K. Although the volume fraction of grain boundary and residual strain of BNII are larger than those of CPII, LTE of BNII at the six measurement directions were less than those of CPII. This phenomenon could be explained with Morse potential function and the crystalline structure of metals. Our LTE results ruled out that the grain boundary and residual strain of BNII did much contribution to its thermal expansion. The higher interaction potential energy of atoms, the less partial derivative of interaction potential energy with respect to temperature T and the porosity free at the grain boundary of BNII resulted in less LTE in comparison with CPII from liquid nitrogen temperature to 300 K. The higher LTE of many bulk nanocrystalline materials resulted from the porosity at their grain boundaries. However, many authors attributed the higher LTE of many nanocrystalline metal materials to their higher volume fraction of grain boundaries.

Suppression of p53 activity by Siva1

The tumor suppressor p53 induces potent anti-proliferative responses in stressed cells; in unstressed cells this ability of p53 is restrained by Hdm2. Expression of Hdm2 is also induced by p53, thereby establishing feedback inhibition. Regulation of the p53-Hdm2 interaction and the feedback inhibition of p53 are not well understood. Here, we show that the p53-Hdm2 interaction in unstressed cells is promoted by Siva1, which, like Hdm2, is the product of a p53 target gene. Siva1 binds to both p53 and Hdm2 through distinct regions and enhances Hdm2-mediated p53 ubiquitination and degradation. Siva1 strongly inhibits p53-mediated gene expression and apoptosis. In xenograft mouse models, downregulation of Siva1 markedly inhibits tumor formation because of the activation of p53. On DNA damage, the interactions of Siva1 with both p53 and Hdm2 are diminished. The function of Siva1 seems to be related to its ability to form a homo-oligomer as the oligomerization defective splicing variant Siva2 fails to de-stabilize p53. These results identify Siva1 as an important adaptor promoting p53 degradation through Hdm2. Siva1 may be part of the negative feedback loop that inhibits p53 activity at the end of a non-lethal stress response.

A comparison of methods for determining HIV viral set point

During a course of human immunodeficiency virus (HIV-1) infection, the viral load usually increases sharply to a peak following infection and then drops rapidly to a steady state, where it remains until progression to AIDS. This steady state is often referred to as the viral set point. It is believed that the HIV viral set point results from an equilibrium between the HIV virus and immune response and is an important indicator of AIDS disease progression. In this paper, we analyze a real data set of viral loads measured before antiretroviral therapy is initiated, and propose two-phase regression models to utilize all available data to estimate the viral set point. The advantages of the proposed methods are illustrated by comparing them with two empirical methods, and the reason behind the improvement is also studied. Our results illustrate that for our data set, the viral load data are highly correlated and it is cost effective to estimate the viral set point based on one or two measurements obtained between 5 and 12 months after HIV infection. The utility and limitations of this recommendation will be discussed.

Activating transcription factor 3 up-regulated by c-Jun NH(2)-terminal kinase/c-Jun contributes to apoptosis induced by potassium deprivation in cerebellar granule neurons

Cerebellar granule neurons (CGNs) depend on potassium depolarization for survival and undergo apoptosis when deprived of depolarizing concentration of potassium. Activating transcription factor 3 (ATF3), a stress-inducible protein, belongs to the ATF/CREB family of transcription factors family and is involved in cell growth and apoptosis. However, the role of ATF3 in neuronal apoptosis remains unknown. Here, we showed that ATF3 was up-regulated under potassium deprivation in CGNs, and this induction was preceded by a rapid and sustained activation of c-Jun NH(2)-terminal kinase/c-Jun signaling pathway, which plays a fundamental role in neuronal apoptosis. Furthermore, ATF3 up-regulation was abolished by inhibition of JNK or knockdown of c-Jun. Finally, knockdown of ATF3 by RNA interference protected CGNs from potassium deprivation-induced apoptosis. Taken together, our results indicate that ATF3 is a downstream target of JNK/c-Jun pathway and contributes to apoptosis induced by potassium deprivation in rat CGNs.

Induction and preliminary characterization of a novel halophage SNJ1 from lysogenic Natrinema sp. F5

Halophage SNJ1 was induced with mitomycin C from Natrinema sp. strain F5. The phage produces plaques on Natrinema sp. strain J7 only. The phage has a head of about 67 nm in diameter and a tail of 570 nm in length and belongs morphologically to the family Siphoviridae. The phage is strongly salt dependent; NaCl concentration affects the integrity of SNJ1, phage adsorption, and plaque formation. The optimal NaCl concentration for phage adsorption and plaque formation is 30% and 25%, respectively.

Identification homologous recombination function from haloarchaea plasmid pHH205

Homologous recombination (HR) was found to be so frequent in haloarchaea that its significance in evolution and diversity of this clade of life might have been underestimated. However, so far there has been no report on recombination function carried on plasmid. Here we report that a 4.8-kb SnaBI-PvuII digested segment from pHH205 might carry such a function. Four constructed plasmids: pUN, pUN-205, pUM and pUM-205, with pUN and pUN205 containing Nov(R) gene, pUM and pUM-205 carrying Mev(R) gene, were used to transform Haloferax volcanii DS52 (radA(-)). The results showed that only pUN-205 and pUM-205 containing the 4.8-kb SnaBI-PvuII digested segment from pHH205 were able to shift Nov(R) and Mev(R) gene into the chromosome of Haloferax volcanii DS52 through HR, whereas those in pUN and pUM could not, which indicated that the segment from pHH205 does contain a recombination function.

Vasoactive intestinal polypeptide enhances oral tolerance by regulating both cellular and humoral immune responses

Vasoactive intestinal polypeptide (VIP) is an important signal molecule of the neuroendocrine-immune network. In the immune system, VIP has been found to act as an endogenous anti-inflammatory mediator. In the current study, it was found that VIP administration regulated oral tolerance by inhibiting both cellular and humoral responses. Compared with vehicle-treated mice, mice treated with VIP during the development of ovalbumin (OVA)-induced oral tolerance exhibited the least delayed-type hypersensitivity (DTH), showed profoundly reduced proliferative capacity and produced less interferon (IFN)-gamma, interleukin (IL)-6, IL-5, IL-10 and interferon-inducible protein (IP-10). IgA-secreting cells in the gut as well as OVA-specific IgG and other isotypes levels in plasma were inhibited significantly after VIP-treatment. The VPAC2 receptor may be involved in VIP-mediated oral tolerance enhancement. Taken together, these results suggest that VIP enhanced oral tolerance via regulating both cellular and humoral responses.

Siah-1S, a novel splice variant of Siah-1 (seven in absentia homolog), counteracts Siah-1-mediated downregulation of beta-catenin

Siah-1 (seven in absentia homolog) is known to cause indirect degradation of beta-catenin through formation of a complex with Siah-interacting protein (SIP), Skp1 and Ebi. Here, we report the characterization of a novel splice variant of human Siah-1, designated Siah-1S, which is produced by an alternative splicing mechanism. The novel intron/exon junctions used to generate Siah-1S follow a non-conventional CT-AC rule. Siah-1S exhibits an even shorter half-life than Siah-1 and is able to catalyse self-ubiquitination that results in its subsequent degradation by proteasome. Siah-1S is shown to upregulate beta-catenin-dependent Tcf/Lef transcriptional activation and antagonize Siah-1's potentiation effect on the apoptosis induced by etoposide in MCF-7 cells. Additionally, Siah-1S is found to interact with Siah-1 to form heterodimer or with itself to form homodimer. Unlike homodimer Siah-1*Siah-1, neither Siah-1*Siah-1S nor Siah-1S*Siah-1S is able to bind to Siah-1-interacting protein, which may explain the underlying mechanism for Siah-1S's dominant negative effect on Siah-1. Importantly, results from in vitro soft agar assay demonstrated that Siah-1S displays a promotion effect on cells tumorigenicity.

Signaling through the TRAIL receptor DR5/FADD pathway plays a role in the apoptosis associated with skeletal myoblast differentiation

Apoptosis rather than differentiation is a physiological process during myogenesis and muscle regeneration. When cultured myoblasts were induced to differentiate, we detected an increase in caspase 8 activity. Pharmacological inhibition of caspase 8 activity decreased apoptosis. Expression of a dominant-negative mutant of the adapter protein FADD also abrogated apoptosis, implicating a death ligand pathway. Treatment with TRAIL, but not Fas, induced apoptosis in these myoblasts. Accordingly, treatment with a soluble TRAIL decoy receptor or expression of a dominant-negative mutant of the TRAIL receptor DR5 abrogated apoptosis. While TRAIL expression levels remained unaltered in apoptotic myoblasts, DR5 expression levels increased. Finally, we also detected a reduction in FLIP, a death-receptor effector protein and caspase 8 competitive inhibitor, to undetectable levels in apoptotic myoblasts. Thus, our data demonstrate an important role for the TRAIL/DR5/FADD/caspase 8 pathway in the apoptosis associated with skeletal myoblast differentiation. Identifying the functional apoptotic pathways in skeletal myoblasts may prove useful in minimizing the myoblast apoptosis that contributes pathologically to a variety of diseases and in minimizing the apoptosis of transplanted myoblasts to treat these and other disease states.

(-)-Epigallocatechin-3-gallate protects mice from concanavalin A-induced hepatitis through suppressing immune-mediated liver injury

(-)-Epigallocatechin-3-gallate (EGCG) is the major active component of green tea. Increasing evidence has suggested that EGCG exhibits anti-inflammatory, anti-oxidant and immunosuppressive effects. In this study, we investigated the effect of EGCG on concanavalin A (ConA)-induced hepatitis (CIH) in mice, a model of immune-mediated liver injury in humans. We pretreated mice with EGCG before ConA injection, and then measured alanine aminotransferase (ALT) levels in plasma, inflammatory infiltration and hepatocyte apoptosis in liver. Potential therapeutic mechanisms were elucidated further by measuring several inflammatory mediators. Mice pretreated with EGCG exhibited much less increased ALT levels in plasma, reduced inflammatory infiltration and hepatocyte apoptosis in liver compared with control mice pretreated with vehicle solutions. We further investigated the mechanisms of the protective effects of EGCG. In EGCG-pretreated mice, we found abrogated tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma at both protein levels in plasma and mRNA levels in liver. At the same time, the concentration of nitrite in plasma and inducible nitric oxide synthase production in liver were both down-regulated in these mice. Moreover, IFN-inducible protein-10 and macrophage inflammatory protein-1alpha expressions in liver were decreased significantly. Therefore, EGCG is capable of regulating immune-mediated liver injury in vivo. The protective effect depended on its suppressive effect on the production of important inflammatory mediators.

Escherichia coli is naturally transformable in a novel transformation system

A novel transformation system, in which neither a nonphysiological concentration of Ca2+ and temperature shifts nor electronic shocks were required, was developed to determine whether Escherichia coli is naturally transformable. In the new protocol, E. coli was cultured normally to the stationary phase and then cultured statically at 37 degrees C in Luria-Bertani broth. After static culture, transformation occurred in bacteria spread on Luria-Bertani plates. The protein synthesis inhibitor chloramphenicol inhibited this transformation process. The need for protein synthesis in plated bacteria suggests that the transformation of E. coli in this new system is regulated physiologically.

Effect of counterions on the swelling of spherical polyelectrolyte brushes

We investigate the swelling of colloidal spherical polyelectrolyte brushes in the presence of different counterions. The colloidal particles consist of a solid poly(styrene) core of ca. 100 nm diameter onto which linear polyelectrolyte chains are chemically grafted. Two types of polyelectrolyte chains have been used here: The cationic polyelectrolyte poly(2-(acryloyl)ethyltrimethylammonium chloride)) (PATAC) and the anionic poly(styrenesulfonate) (PSS). Both systems are dispersed in water and the degree of swelling of the surface layer is studied by dynamic light scattering. Adding more and more salt leads to a strong shrinking of the surface layer as expected for polyelectrolyte brushes. It is shown that data obtained at low ionic strength can be collapsed on suitable master curves for monovalent and divalent counterions, respectively. For some ions, however, high salt concentrations may lead to a re-swelling of the brush layer in case of the cationic systems. This points to specific interactions of the counterions with the PATAC chains. This strong specific interaction between the counterions and the attached polyelectrolyte may even lead to flocculation of the particles at intermediate salt concentration. Surprisingly, for iodide and magnesium counterions the solubility increases again if the salt concentration is raised to 1 mol/l. Hence, specific interaction leads to salting-out effects as well as to salting-in effects for these colloidal particles. All specific effects seen at high concentrations of added salt can be explained by the increase of the reduced excluded-volume parameter which is due to the adsorption of salt ions.

Reversal of cancer multidrug resistance by tea polyphenol in KB cells

Tea polyphenols, (-)-epigallocatechin gallate in particular, were examined for their modulating effects on the drug resistance KB-A-1 cells and drug sensitive KB-3-1 cells. Both KB-3-1 and KB-A-1 cells were equally sensitive to tea polyphenol and (-)-epigallocatechin gallate. When 10 microgram/ml (-)-epigallocatechin gallate or 40 microgram/ml tea polyphenol were present simultaneously with doxorubicin, the IC50 of doxorubicin on KB-A-1 cells decreased from 10.3 +/- 0.9 microgram/ml to 4.2 +/- 0.2 or 2.0 +/- 0.1 microgram/ml. Tea polyphenol and (-)-epigallocatechin gallate enhanced the cytotoxicity of doxorubicin on KB-A-1 cells by 5.2 and 2.5 times, respectively, but did not show a modulating effect on KB-3-1 cells. Both tea polyphenol and (-)-epigallocatechin gallate showed reversal effects on the multidrug resistance phenotype.

Apoptosis coincident with the differentiation of skeletal myoblasts is delayed by caspase 3 inhibition and abrogated by MEK-independent constitutive Ras signaling

We demonstrate that during 23A2 skeletal myoblast differentiation, between 30-35% of the population apoptose. Both differentiation and apoptosis are controlled by the variables of cell density and time and these variables are inversely related. In response to conditions that permit both differentiation and apoptosis of parental 23A2 myoblasts, myoblasts rendered differentiation-defective by constitutive Ras signaling (A2:H-Ras myoblasts) do not apoptose. This is not merely a consequence of their differentiation-defective phenotype since myoblasts rendered differentiation-defective by expression of E1A (A2:E1A myoblasts) still apoptose. Although signaling through MEK is important to the survival of proliferating parental 23A2 myoblasts, constitutive signaling through MEK is not responsible for the survival of A2:H-Ras myoblasts. Finally, we demonstrate that caspase 3 is activated and that pharmacological inhibition of caspase 3 activity delays apoptosis without affecting differentiation. Abrogating apoptosis without affecting differentiation could be a useful approach to improve the efficacy of myoblast transfer in the treatment of muscular dystrophies.

Activation of melatonin receptor increases a delayed rectifier K+ current in rat cerebellar granule cells

The present study was initiated to investigate the effect of melatonin on K+ current in rat cerebellar granule cells for 2 to 6 days in culture (DIC). The whole-cell configuration of the conventional patch-clamp technique was used to record the outward K+ current. Two types of outward K+ current, a transient outward K+ current and a delayed rectifier K+ current, were separated by different voltage protocols and a specific blocker of K+ channel. Application of melatonin (10 microM) by a brief pressure ejection induced a significant and reversible increase of the delayed rectifier K+ current amplitude in 78% of the cells tested. The activated effect of melatonin on the K+ current was independent of the time in culture, and the percentage of activation remained at a relatively stable level from 2 DIC to 6 DIC; but that was dependent on the concentration of melatonin applied. The activation of the K+ current induced by melatonin presented no desensitization after repeated application of melatonin. The effect of melatonin on the K+ current can be mimicked by 2-iodomelatonin, a melatonin receptor agonist. With the addition of guanosine-5'-O-(3-thiophosphate) in the pipette solution, melatonin caused a stronger activation effect on the K+ channels, and an irreversible increase of the current amplitude in some granule cells tested. Pretreatment of cells with PTX suppressed the action of melatonin on the K+ current in most granule cells studied. In addition, the activation curves and inactivation curves tested with the steady-state activation and inactivation protocols were unchanged by melatonin, suggesting that melatonin did not modulate the channel's activation and inactivation properties. Our results demonstrated the presence of a functional melatonin receptor in cultured cerebellar granule cells from neonatal cerebellum. Activating the receptor can modulate the outward K+ currents by coupling to a PTX-sensitive G protein.

[Effect of PAI-1 antisense RNA on vascular endothelial growth factor expression in aorta smooth muscle cells cultured in vitro]

OBJECTIVE

To investigate the role of plasminogen activator inhibitor-1(PAI-1) antisense RNA in regulating the expression of PAI-1 and vascular endothelial growth factor (VEGF) in aorta smooth muscle cells cultured in vitro.

METHODS

The second extron of PAI-1 was amplified with polymerase chain reaction(PCR), the production was inserted into eukaryotic cell expression vector pcDNA3.1 after it had been purified and cloned so as to construct PAI-1 antisense RNA recombination plasmid. The recombination plasmid was transfected into SMC. PAI-1 expression was detected by immunohistochemistry, Western blod and ELISA; the effects of PAI-1 variation on VEGF was examined by immunofluorescence.

RESULTS

PAI-1 antigen was the lowest in cells on the third day after transfection; the expression of VEGF was also decreased. PAI-1 antigen gradually increased on the fifth day and VEGF increased correspondingly. On the seventh day, PAI-1 antigen and VEGF increased to nearly normal level.

CONCLUSION

PAI-1 antisense RNA can block the translation progress of PAI-1 proteins effectively and inhibit the expression of VEGF in aorta smooth muscle cells.

Cytokine-induced cell surface expression of adhesion molecules in vascular endothelial cells in vitro

Regulation of the adhesion molecules expression by cytokine in vascular endothelial cells was investigated. Human umbilical vein endothelial cells (HUVEC) were stimulated with cytokines, TNF-alpha (1-250 U/ml) or IL-1 beta (0.1-50 U/ml) for 24 h. HUVEC were also cultured with cytokines, TNF-alpha (100 U/ml) or IL-1 beta (10 U/ml), for 4-72 h, cell surface expression of adhesion molecules (ICAM-1 and VCAM-1) were detected and quantitated by immunocytochemical methods and computerized imaging analysis technique. Adhesion molecules expression were up-regulated by TNF-alpha, IL-1 beta in a concentration- and time-dependent manner. Some significant differences were observed between the effects of cytokines on the ICAM-1 and on VCAM-1 expression. Cytokines might directly induce the expression of ICAM-1 and VCAM-1 in vascular endothelial cells. Our observations indicate differential functions of the two adhesion molecules during the evolution of inflammatory responses in stroke.

Effect of diazepam on the contents of amino acids and free radical during ischemia/reperfusion injury

The protective effect and mechanism of diazepam on ischemia neurons during cerebral ischemia and reperfusion were studied. Sixty-three Wistar rats were divided randomly into nine groups: control group (n = 7), ischemia (is) groups including subgroups of is3 h, is3-h/rep1-h, is3-h/rep2-h, is3-h/rep3-h(n = 7 in each group), diazepam treated groups (10 mg/kg, i.p.), including subgroups of is3-h, is3-h/rep1-h, is3-h/rep2-h, is3-h/rep3-h (n = 7 in each group) with Zea longa's animal model of middle cerebral artery occlusion. The comparison between the ischemia group and diazepam-treated group showed that diazepam could obviously decrease the production of glutamate, asparate, MDA and increase the synthesis and release of GABA, SOD and GSH-PX. It was concluded that diazepam exerted its protective effects on neurons through complex mechanisms of regulating the synthesis and release of excitotary/inhibitory amino acids and free radicals.

Effect of magnesium on nitric oxide synthase of neurons in cortex during early period of cerebral ischemia

To investigate the effect of magnesium on nitric oxide synthase (NOS) of neurons in cortex during early cerebral ischemic period, a rat model of middle cerebral artery occlusion (MCAO) was established. The results showed that the NOS activity of neurons in cortex was increased significantly at 15 min after MCAO, reached its peak at 30 min after MCAO and returned to normal levels at 60 min after MCAO. The NOS activity of neurons in the magnesium-treated group was decreased significantly as compared with that in the ischemic group at 15 min and 30 min after MCAO respectively. The results suggested that magnesium could inhibit the elevated NOS activity of neurons in cortex induced by cerebral ischemia.

A role of p75 in NGF-mediated down-regulation of the A(2A) adenosine receptors in PC12 cells

Nerve growth factor (NGF) induces differentiation of the rat pheochromocytoma clone (PC12) by activating the high affinity receptor, p140(trkA), linked to mitogen-activated protein kinase. While the physiological role of the low affinity NGF receptor (p75) has not been clearly defined, this receptor promotes activation of nuclear factor (NF) kappaB in Schwann cells. PC12 cells express the A(2A) adenosine receptor (AR), whose expression is significantly decreased by NGF treatment. In this study, we determined whether TrkA or p75 is involved in NGF-mediated regulation of A(2A)AR expression. NGF treatment decreased A(2A)AR in a time-dependent manner, with maximal effects observed by 1 day, and continued down-regulation of the receptor for up to 3 days in the presence of NGF. The decrease in A(2A)AR was associated with a more delayed decrease in the steady-state levels of the A(2A)AR mRNA. Down-regulation of the A(2A)AR at 1 day was mimicked by activators of NFkappaB, such as H(2)O(2), and ceramide, and was attenuated by the inhibitor pyrrolidine dithiocarbamate or following transient transfection of PC12 cells with a dominant negative IkappaBalpha mutant. Moreover, NGF stimulated nuclear accumulation of p65 subunits of NFkappaB (but not p50 subunits) in PC12 cells, as determined by electrophoretic mobility shift assays and by Western blotting. In contrast, inhibition of TrkA by AG879 or of TrkA-dependent mitogen-activated protein kinase mitogen-activated protein kinase kinase with PD98059 blocked PC12 cell differentiation without affecting A(2A)AR down-regulation, suggesting dissociation between these two phenomena. Taken together, these data provide strong support for the involvement of the p75/NFkappaB pathway in NGF-mediated down-regulation of A(2A)AR in PC12 cells.

[A preliminary study of two Chinese herbs protective tablets on some Chinese traditional medicines]

The protective action of 2 tablets of Chinese herb to 5 Chinese traditional medicines against harm of insects and mildews was tested. It was found that 2 tablets have a obvious effects of insect-repellency and mouthproof in the test with Homalomena occulta and Prunus armeniaca, the bore in the medicinal materials was decreased 94.95% and 95.55% respectively than that of check. The tablets have some effects of mildewproof in the test with Tussilago farfara.

Age-related reductions in the activities of antioxidant enzymes in the rat inferior colliculus

The inferior colliculus (IC) is a major relay and processing center of auditory signals in the midbrain and receives inputs from most other auditory nuclei. A number of studies have indicated age-related declines in the GABAergic and excitatory amino acid systems in the IC, including losses in both GABA immunoreactive (+) and GABA immunonegative (-) synapses. The goal of this project was to identify potential biochemical and morphological changes in the IC that may contribute to deficits in the functions of these neurotransmitters, using three age groups of Fischer-344 rats. Homogenates obtained from the IC showed age-dependent reductions in activities of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), with a concomitant increase in lipid peroxidation. Dephosphorylation of IC homogenates with alkaline phosphatase reduced the activities of SOD and CAT in all age groups, which could be restored by protein kinase C (PKC)-dependent phosphorylation. Restoration of enzyme activity was specific to the PKC-alpha isozyme, but not to the beta1, beta2, delta or gamma forms. No age-dependent change in the levels of PKC isoforms (alpha, beta1, beta2 and gamma) was detectable in IC homogenates. Morphological analyses indicate decreases in mitochondrial density in the somata of both GABA+ and GABA- IC neurons in 19- and 28-month-old rats when compared to 3-month-olds, along with significantly higher matricial abnormalities. These data indicate age-related increases in oxidative stress in the IC, which could be partially restored by PKC. The progressive increase in oxidative stress with age may underlie changes in neuronal morphology and function of the IC.

Development of bovine IVF oocytes cultured in medium supplemented with a nitric oxide scavenger or inhibitor in a co-culture system

Bovine IVF oocytes were cultured in modified bovine embryo culture medium (mBECM) supplemented with either a nitric oxide (NO) scavenger, hemoglobin (Hb, 1 microg/mL) and/or a NO synthesis inhibitor, L(omega)-nitro-L-arginine methyl ester (L-NAME, 1 or 1000 nM) in a cumulus-granulosa cell co-culture system. In Experiment 1, a total of 1,675 cumulus-oocytes complexes was collected for 7 mo and cultured to the blastocyst stage in mBECM with or without Hb after IVM and IVF. There were significant (P<0.0024) model effects of Hb addition and month of oocyte collection on embryo development. A significant (P<0.0023) monthly variation was detected in all developmental stages. However, addition of Hb to mBECM consistently enhanced embryo development to the blastocyst stage over all months. No statistical differences were found in the interaction between Hb addition and month except for the cleavage rate. Overall, a greater percentage of oocytes developed to the 8-cell (P<0.0459), 16-cell (P<0.001), morula (P<0.0013) and blastocyst (P<0.0024) stages after the addition of Hb. In Experiment 2, addition of L-NAME to mBECM supplemented with Hb did not further stimulate prehatched development. In conclusion, the promoting effect of Hb on in vitro development of embryos is highly repeatable over an extended period of time.

[Early changes in rat lungs caused by lower-dose quartz dust]

OBJECTIVE

To study the features of damages in the lungs caused by lower dose quartz.

METHODS

Cell count, contents of protein and total lipid and activity of lactate dehydrogenase (LDH) in bronchoalveolar lavage, changes in content of collagen in the whole lungs of the rats were determined after their exposure to lower dose quartz and asbestosdust (10 mg per rat), and pathological changes in the lungs were also observed.

RESULTS

Cell count, contents of protein and total lipid and activity of lactate dehydrogenase in bronchoalveolar lavage, and content of total collagen in the whole lungs increased persistently in the rats exposed to quartz; and, only cell count and activity of lactate dehydrogenase increased transiently in rats 10 days after exposure to asbestos, and content of collagen also increased gradually, but not so obviously as caused by quartz.

CONCLUSION

Lower dose quartz has very strong toxicity to the lungs leading to pulmonary fibrosis.

Oxidative stress increases A1 adenosine receptor expression by activating nuclear factor kappa B

The A1 adenosine receptor (A1AR) contributes to the cytoprotective action of adenosine under conditions known to generate reactive oxygen species (ROS). Pharmacological manipulation of A1AR expression has been shown to modulate this cytoprotective role. In this study, we provide evidence that ROS generated could increase the expression of the A1AR and thereby offset the detrimental effects of ROS. Incubation of DDT1MF-2 smooth muscle cells with ROS-generating chemotherapeutic agents, such as cisplatin (2.5 microM) or H2O2 (10 microM), elicited an increase in A1AR expression within 24 hr. The induction by H2O2 was reduced by the ROS scavenger catalase but not superoxide dismutase. Inhibition of nuclear factor kappa B (NF kappa B) by pyrrolidine dithiocarbamate (200 microM), dexamethasone (100 nM), or genistein (1 microM) abrogated the cisplatin-mediated increase in A1AR. Cisplatin promoted rapid translocation of NF kappa B (but not AP-1) to the nucleus, as detected by electrophoretic mobility shift assays and by Western blotting. A putative NF kappa B sequence in the A1AR promoter effectively competed with labeled kappa B probe for binding in nuclear preparations derived from DDT1MF-2 cells. Transient transfection of DDT1MF-2 cells with the A1AR promoter coupled to firefly luciferase reporter gene led to cisplatin-inducible and pyrrolidine dithiocarbamate-sensitive luciferase activity, suggesting the presence of functional NF kappa B binding site(s) in the A1AR promoter sequence. Treatment of cells with (R)-phenylisopropyladenosine (1 microM), an agonist of the A1AR, reduced cisplatin-mediated lipid peroxidation, which was reversed after blockade of the A1AR. These data suggest that ROS can increase the expression of the A1AR by activating NF kappa B regulatory site(s) on this gene and thereby enhance the cytoprotective role of adenosine.

Beta-amyloid precursor protein-like immunoreactivity is upregulated during olfactory nerve regeneration in adult rats

Beta-amyloid precursor protein (APP) is the source of beta-amyloid, which forms the cores of senile plaques in Alzheimer's Disease. However, the function of this precursor protein is currently unknown and an adult animal in which this protein varied substantially would be valuable. We used subcutaneous diethyldithiocarbamate to reversibly lesion the olfactory epithelium in adult rats and found that whole-bulb levels of APP-like immunoreactivity significantly decreased after the lesion, then increased reaching almost five-fold normal levels six weeks after treatment. Growth cone associated protein (GAP43) decreased when the nerve degenerated, then increased, replicating previous studies of olfactory nerve regeneration. Immunocytochemical techniques identified APP immunoreactive perikarya and fibers in and around glomeruli at three days to one week post-lesion and upregulation of APP-like immunoreactivity in mitral cells and dendrites at five weeks. Olfactory nerve regeneration appears to be a useful in vivo model system to understand the regulation of APP-like proteins.

Short term desensitization of the A1 adenosine receptors in DDT1MF-2 cells

Previous studies have indicated that desensitization of the A1 adenosine receptor (A1AR), unlike other adenosine receptor subtypes and G protein-coupled receptors, required prolonged exposure to agonists. We more closely studied this observation by focusing on changes in the A1AR signal transduction pathway after short term agonist exposure (0.5-4 hr) in the hamster vas deferens smooth muscle cell line (DDT1MF-2 cells). Incubation of these cells with 1 microM (R)-phenylisopropyladenosine [(R)-PIA] produced a time-dependent loss in binding of the agonist radioligand [125I]N6-2-(4-amino-3-iodophenyl)ethyladenosine but not of the antagonist radioligand [3H]8-cyclopentyl-1,3-dipropylxanthine. This was accompanied by a reduction in the high affinity (G protein-coupled) state of this receptor from 63 +/- 8% to 37 +/- 12% after treatment for 4 hr. Moreover, cells treated with (R)-PIA demonstrated reduced agonist-stimulated GTPase activity and diminished inhibition of adenylyl cyclase activity but no change in expression of alphai and beta subunits. The decreases in agonist binding in the desensitized cells were reversible after treatment of DDT1MF-2 cell membranes with alkaline phosphatase or protein phosphatases 1 and 2A, suggesting a role of phosphorylation in the uncoupling and desensitization of the A1AR. Incubation of cells with (R)-PIA led to rapid translocation of G protein-coupled receptor kinase (GRK) from the cytosol to the plasma membrane within 1 hr of exposure. In addition, purified preparations of the A1AR that were phosphorylated with purified recombinant GRK-2 demonstrated enhanced affinity for arrestin over Gi/Go. These results indicate rapid and functional desensitization of the A1AR by brief exposure to agonist. The mechanism underlying this event seems to involve phosphorylation of the A1AR, presumably by the GRK or GRKs.

[Study on the distribution and origins of RNA in the metaphase chromosomes of mouse by in situ hybridization at electron microscopic level]

The RNAs in the metaphase chromosomes of mouse are located by use of RNase-gold labelling. The result shows that a lot of RNAs distribute uniformly in the inner and peripheral regions of the chromosome sections. Moreover, the distributions of 18 s rRNA and 5 s rRNA which are studied under the electron microscope by in situ hybridization indicate that 18 s rRNA and 5 s rRNA are two among the several origins of the inner RNAs and peripheral RNAs in mouse metaphase chromosomes.

Inhibition of epidural scar formation after lumbar laminectomy in the rat

STUDY DESIGN

An animal model of laminectomy in rats was used to study scar tissue formation around the spinal cord. Dexamethasone, in controlled-release form, was tested in this system for its ability to decrease fibrous tissue formation.

OBJECTIVES

The results were evaluated to determine whether dexamethasone in a biodegradable controlled-release vehicle could be used to limit scar tissue formation around the spinal cord after laminectomy.

SUMMARY OF BACKGROUND DATA

Steroids can delay the formation of scar tissue. Continued treatment with dexamethasone results in various unacceptable side effects. Use of biodegradable controlled-release vehicles to deliver drugs may allow for prolonged low-dose treatment, concentrated at the surgical site, thereby avoiding side effects.

METHODS

Forty-four Sprague Dawley rats underwent laminectomies and were treated with dexamethasone in one of two controlled-release vehicles or with vehicle alone. After 4 weeks, the rats were killed and histologic sections prepared from the spines were examined and graded by a pathologist. In addition, the dexamethasone preparations were introduced into Hunt-Schilling wound chambers, which were implanted in rats. Four weeks after implantation, the wound chambers were removed and the tissue inside was assayed for DNA and protein content.

RESULTS

Dexamethasone acetate (Decadron, MSD, West Point, PA) significantly reduced the density of the scar tissue undermining the laminas. Steroids embedded in polymer did not change the scar formation in the back, but did decrease protein and DNA values in wound chamber tissues.

CONCLUSIONS

Long-term release of small amounts of steroid from the polymer poly-carboxy-phenoxypropane does not appear to reduce scar at laminectomy sites but does decrease the protein:DNA ratio in wound chambers. In contrast, Decadron does not significantly alter the biochemistry of wound chamber tissue but does reduce scar in the back.

Effects of target gas in collision-induced dissociation using a double quadrupole mass spectrometer and radiofrequency

Collision-induced dissociation (CID) of polyatomic ions sampled from an rf-powered glow discharge is examined by using three target gases including atomic (Ar and Xe) and molecular species (N2). Collisions with these targets in the first quadrupole of the double quadrupole system result in the loss of discharge species by dissociation, symmetric and asymmetric charge exchange, and scattering, each to varying degrees. These processes are seen to be a function of the relative mass, size... and ionization potentials of the target species, as well as the collision center-of-mass energies. In light of the comparisons, xenon appears to be the best collision target for both CID and charge exchange because of its relatively low ionization potential and high dissociation efficiency of polyatornic species. Evidence for both symmetric and asymmetric charge exchange is presented for Ar and Xe target gases.