Lack of association of VEGF promoter polymorphisms with sporadic ALS

The authors tested the association of three vascular endothelial growth factor (VEGF) promoter polymorphisms with sporadic ALS (SALS) to verify the results of a previous study and to investigate their modifier effects on the subphenotypes of SALS in a large family-based and case-control cohort of North American white subjects (N = 1,603). They did not find any association of the VEGF promoter polymorphisms with SALS or its subphenotypes, suggesting that they do not have a direct causal role in ALS.

Synergistic antitumor effect of tumor necrosis factor-related apoptosis-inducing ligand combined with cisplatin in ovarian carcinoma cell lines in vitro and in vivo

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to exert selectively cytotoxic activity against many tumor cells but not normal cells. In this study, we evaluated the antitumor activity of TRAIL and cisplatin (CDDP) both separately and combined in the human ovarian cancer cell lines. In vitro study showed that TRAIL elicited significant cell apoptosis of cell lines 3AO, SKOV3, and OVCAR3 in a dose- and time-dependent manner (P < 0.05), while normal ovarian epithelial cells were resistant; this toxicity-free effect may be the result of upregulation of TRAIL receptors DcR1 and DcR2. Combined TRAIL and CDDP therapy produced more profound cell killing in 3AO cells than each alone (P < 0.05), and CDDP could upregulate the expression of both death and decoy TRAIL receptors. To further evaluate the apoptosis-inducing effects of TRAIL and the combination therapy, the abdominally and subcutaneously spread tumors in nude mice via inoculation of 3AO cells were established, and treatment of TRAIL resulted in a dose- and time-dependent inhibition of tumor growth while slight damage was observed in normal tissues. Furthermore, combined TRAIL and CDDP therapy had a synergistic effect in the regression of established ovarian cancer xenografts than TRAIL treatment alone (P < 0.05). We also examined the apoptosis-related gene expression in the transplantation tumors after TRAIL treatment, and the data suggested that the intracellular mechanism of TRAIL may be associated with downregulation of Bcl-2 and upregulation of CD95 and Apo2.7.

[Determination of chlorhexidine acetate in disinfectors by capillary electrophoresis]

A method for the determination of chlorhexidine acetate in disinfectors using capillary electrophoresis (CE) was developed using the following conditions: detection wavelength, 254 nm; applied voltage, 15 kV; uncoated fused silica capillary column, 50 cm x 75 microm i.d.; buffer, 15 mmol/L phosphate and acetonitrile (60:40, v/v). Under the optimum conditions, chlorhexidine acetate in disinfectors was determinated in 4 min. The effects of different parameters, such as buffer component, buffer concentration, buffer pH value and electrophoretic voltage, on the CE analysis of chlorhexidine acetate were studied in detail. The linear range of the proposed method was 0.01-0.10 g/L. The detection limit was 0.004 mg/L. The relative standard deviation (RSD) of absorbance was 3.97% and the RSD of migration time was 2.99%. The spiked recoveries of samples were 91.4%-116.6%. The method was compared with the high performance liquid chromatographic method and the relative error was less than 4.0%. The proposed method was simple, quick and suitable for disinfector analysis.

Direct interaction between α-actinin and hepatitis C virus NS5B

It has been suggested that cellular proteins are involved in hepatitis C virus (HCV) RNA replication. By using the yeast two-hybrid system, we isolated seven cDNA clones encoding proteins interacting with HCV RNA polymerase (NS5B) from a human liver cDNA library. For one of these, alpha-actinin, we confirmed the interaction by coimmunoprecipitation, immunofluorescent staining and confocal microscopic analysis. Experiments with deletion mutants showed that domains NS5B(84-95), NS5B(466-478), and alpha-actinin(621-733) are responsible for the interaction. Studies of the HCV subgenomic replicon system with small interference RNA indicate that alpha-actinin is essential for HCV RNA replication. Our results suggest alpha-actinin may be a component of the HCV replication complex.

The ability of an HSV strain to initiate zosteriform spread correlates with its neuroinvasive disease potential

The requirements for disease development in the mouse epidermal scarification-zosteriform model of HSV infection are likely to parallel those required for primary HSV disease of humans. HSV-1 strains, which are neuroinvasive in the mouse footpad model of HSV encephalitis, caused local site lesions within 3 days and secondary zosteriform lesions along the dermatome within approximately 5 days. HSV-1 strains, which are not neuroinvasive, failed to progress to zosteriform lesion development and local site lesions were mild or absent. Relative differences in the rate and extent of zosteriform lesion development paralleled the behavior of the viruses in the mouse footpad model of neuroinvasion. In conclusion, the viral properties which are important for neuroinvasiveness appear to also determine the ability of an HSV strain to cause zosteriform disease.

Electrorheological fluid under elongation, compression, and shearing

Electrorheological (ER) fluid based on zeolite and silicone oil under elongation, compression, and shearing was investigated at room temperature. Dc electric fields were applied on the ER fluid when elongation and compression were carried out on a self-constructed test system. The shear yield stress, presenting the macroscopic interactions of particles in the ER fluid along the direction of shearing and perpendicular to the direction of the electric field, was also obtained by a HAAKE RV20 rheometer. The tensile yield stress, presenting the macroscopic interactions of particles in the ER fluid along the direction of the electric field, was achieved as the peak value in the elongating curve with an elongating yield strain of 0.15-0.20. A shear yield angle of about 15 degrees -18.5 degrees reasonably connected tensile yield stress with shear yield stress, agreeing with the shear yield angle tested well by other researchers. The compressing tests showed that the ER fluid has a high compressive modulus under a small compressive strain lower than 0.1. The compressive stress has an exponential relationship with the compressive strain when it is higher than 0.1, and it is much higher than shear yield stress.

[Clinical significance of MDR gene expression in malignant pleural effusion and ascites and solid tumors]

OBJECTIVE

To discuss the guiding significance of multidrug resistance (MDR) gene expression for monitoring the clinical effectiveness of chemotherapy upon cancer, and to analyze the MDR1 and glutnthione-s-transferase(GST-pi) mRNA expression rates in primary breast cancer, and their correlation with the clinical outcome and prognosis.

METHODS

The mRNA expression levels of MDR1 in 16 cases with malignant pleural effusion and ascites and 102 cases of solid tumors were measured using semiquantitative RT-PCR assay. The MDR1 and GST-pi mRNA expression rates in 84 cases of breast cancer, out of the 102 cases of solid tumors, were also studied in the same way.

RESULTS

(1) An average coincidence rate of 84.5% was found between the mRNA expression level of MDR1 and the clinical response to chemotherapy in the 16 cases with malignant pleural effusion and ascites and 18 cases of solid tumors. (2) The positive rate of MDR1 mRNA expression in primary breast cancer tissue was 79.7%, with the medium and high levels as high as 33.3%, while the positive rate of GST-pi mRNA expression was 33.3%, with the medium and high expression levels being as low as 4.8%. There was a highly significant difference between the two groups (P < 0.01). The positive rates of MDR1 mRNA in the group having received chemotherapy before surgery and the group not receiving chemotherapy before surgery were 87.8% and 68.6% respectively, showing a lymph nodes and in the group without metastases in axillary lymph nodes were 89.1% and 68.4% respectively, indicating a significant difference (P < 0.05). The positive rates of GST-pi mRNA in the group suffering distant metastases and the group not suffering distant metastases were 71.4% and 20.6% respectively, showing a significant difference (P < 0.05). The GST-pi mRNA expression rates in the estrogen receptor (ER)- and progesterone receptor (PR)-positive groups were higher than those in the ER- and PR-negative groups, indicating a significant difference (P < 0.05) .

CONCLUSION

The mRNA expression level of MDR1 has a relatively high correlation with the clinical response to chemotherapy, and thus can be used to monitor the effectiveness of chemotherapy. MDR1 is the main drug resistance mechanism in breast cancer. Chemotherapy before surgery induces MDR1 mRNA expression. MDR1 e xpression and GST-pi mRNA expression serve as a significant prognostic indicator for breast cancer, thus having guiding significance for assessing prognosis.

Spectroscopic studies of the vibrational and electronic properties of solid hydrogen to 285 GPa

We report Raman scattering and visible to near-infrared absorption spectra of solid hydrogen under static pressure up to 285 GPa between 20 and 140 K. We obtain pressure dependences of vibron and phonon modes consistent with results previously determined to lower pressures. The results indicate the stability of the ordered molecular phase III to the highest pressure reached and provide constraints on the insulator-to-metal transition pressure.

Consolidation of human memory over decades revealed by functional magnetic resonance imaging

Medial temporal lobe (MTL) lesions typically produce retrograde amnesia characterized by the disproportionate loss of recently acquired memories. Temporally graded memory loss is interpreted traditionally as evidence for a consolidation process guided by the MTL. Here, using functional magnetic resonance imaging (fMRI), we show temporally graded changes in MTL activity in healthy older adults taking a famous faces remote memory test. Evidence for temporally graded change in the hippocampal formation was mixed, suggesting it may participate only in consolidation processes lasting a few years. Entorhinal cortex was associated with temporally graded changes extending up to 20 years. These findings support the basic tenets of consolidation theory and suggest that the entorhinal cortex, rather than the hippocampal formation, participates in memory consolidation over decades.

Rational design of diflunisal analogues with reduced affinity for human serum albumin

Many lead compounds bind to serum albumin and exhibit markedly reduced efficacy in vivo as compared to their potency in vitro. To aid in the design of compounds with reduced albumin binding, we performed nuclear magnetic resonance (NMR) structural and binding studies on the complex between domain III of human serum albumin (HSA-III) and diflunisal, a cyclooxygenase inhibitor with antiinflammatory activity. The structural studies indicate that the aromatic rings of diflunisal are involved in extensive and specific interactions with hydrophobic residues that comprise the binding pocket in subdomain IIIA. The carboxylic acid of diflunisal forms electrostatic interactions with the protein similar to those observed in the X-ray structure of HSA complexed to myristic acid. In addition to the structural studies, NMR-derived binding constants were obtained for diflunisal and closely related analogues to develop a structure-affinity relationship for binding to subdomain IIIA. On the basis of the structural and binding data, compounds were synthesized that exhibit more than a 100-fold reduction in binding to domain III of HSA, and nearly a 10-fold reduction in affinity for full length albumin. Significantly, several of these compounds maintain activity against cyclooxygenase-2. These results suggest a rational strategy for designing out albumin binding in potential drug molecules by using structure-based design in conjunction with NMR-based screening.

The context of uncertainty modulates the subcortical response to predictability

Implicit motor learning tasks typically involve comparisons of subject responses during a sequence versus a random condition. In neuroimaging, brain regions that are correlated with a sequence are described, but the temporal relationship of sequence versus nonsequence conditions is often not explored. We present a functional magnetic resonance imaging (fMRI) study describing activation related to sequential predictability in an implicit sensorimotor learning task and the history (context) dependence of these effects. Participants regarded four squares displayed horizontally across a screen and pressed a button when any one of the four targets was illuminated in a particular color. A repeating spatial sequence with varying levels of predictability was embedded within a random color presentation. Both the right dorsolateral prefrontal cortex (R DLPFC) and right caudate displayed a positive correlation to increasing predictability, whereas the left posterior parietal cortex (L PPC) displayed a negative correlation. However, the activation changes within the caudate were significant when transitioning from high predictability to low predictability but not for the reverse case, suggesting a sensitivity not only to predictability but to order effects as well. These results support the hypothesized relationship between basal ganglia and visuomotor sequential learning, but demonstrate the importance of context upon sequence learning.

Changes in BiP (GRP78) levels upon HSV-1 infection are strain dependent

BiP (grp78) is a chaperone protein which can also regulate the unfolded protein response of the cell. Levels of BiP increased in cells infected by the small plaque producing, cell associated, neuroinvasive strains of HSV-1 (SP7, 490) but decreased in cells infected with KOS, a large plaque, attenuated strain. BiP protein synthesis continued early in infection and BiP was sequestered and its degradation was limited during SP7 infection. BiP protein synthesis stopped and the protein was degraded in KOS infected cells. These viral strain dependent differences in BiP concentration may influence other aspects of the viral interaction with the target cell and its host.

[Effects of vascular endothelial growth factor on adhesion molecular expression of hepatocellular carcinoma HepG]

OBJECTIVE

To study the effect of vascular endothelial growth factor (VEGF) on homotypic adhesion and E-cadherin of hepatocellular carcinoma cells.

METHODS

We measured the function of homotypic adhesion with (3)H-TdR infiltration and the expression of E-cadherin with laser scanning confocal microscope.

RESULTS

After 60, 90, 120min, the values (dpm/min) of (3)H-TdR infiltration in HepG(2) cells induced by 1ng/ml, 5ng/ml VEGF were 1758.67+/-289.46, 1380.03+/-328.55, 2657.43 +/- 310.31 and 3124.30+/-262.14, 2245.60+/-273.24, 2091.52+/-213.84. The values by 10ng/ml VEGF were 1232.32+/-201.04, 2337.50+/-333.04, 2236.99 +/- 237.07, which were significantly lower than those in control group (P<0.05 or 0.01). The expression of E-cadherin in hepatocellular carcinoma cells induced by 5ng/ml VEGF was 352+/-56 and much lower than that in control group (757+/-103, P<0.01).

CONCLUSIONS

VEGF can decrease homotopic adhesion of hepatocellular carcinoma HepG(2) cell, which is connected with the less expression of E-cadherin in hepatocellular carcinoma HepG(2) cell.

[Expression of nm23 in breast cancer: correlation with distant metastasis and prognosis]

OBJECTIVE

To investigate the relationship between expression of nm23 gene and distant metastasis and prognosis in breast cancer.

METHODS

To detect nm23 protein expression in 101 patients with breast cancer by means of immunohistochemistry and nm23 mRNA expression in 68 patients with breast cancer by RT-PCR.

RESULTS

Expression of nm23 gene was inversely correlated with distant metastasis and lymph node metastasis. Among 9 patients with negative node but with distant metastasis, 7 had low expression of nm23. In 29 patients with positive nodes but without distant metastasis, 24 had high expression of nm23, while 6 of 6 patients with positive nodes and distant metastasis expressed high levels of nm23 mRNA.

CONCLUSION

Expression of nm23 gene, tumor size and status of axillary lymph node are independent prognostic indicators to breast cancer prognosis.

Loss of nm23 expression predicts distal metastases and poorer survival for breast cancer

The nm23 gene, originally identified by differential hybridization of metastatic murine melanoma cell lines has been associated with decreased metastatic potential. In this study, we evaluated the utility of nm23 expression levels as a predictive and a prognostic biomarker for distal metastases and poor survival in a Chinese cohort of 168 breast cancer patients. Our study indicates that high nm23 expression is associated with older age (older than 35 years) and smaller tumor size. There is no statistically significant association between nm23 expression and pathologic type or axillary metastasis. High nm23 expression is associated with the absence of distal metastases. Nearly 80% of women with high nm23 expression are alive after 10 years compared to 25% with low expression; at five years the cumulative survival proportions are 86% and 46%, respectively. The Cox model for survival indicates that controlling for tumor size and presence of axillary metastases at diagnosis, the hazard for women with low nm23 expression is nearly 4 times that of women with high nm23 expression. Low nm23 expression is predictive of distal metastases and appears to be a risk factor that is independent of the presence or absence of positive axillary nodes at diagnosis.

Fabrication of phospholipid bilayer-coated microchannels for on-chip immunoassays

Herein we describe a new class of microfluidic immunoassays based upon solid supported lipid bilayers. Two-dimensionally fluid bilayer material, which can accommodate multivalent binding between surface-bound ligands and aqueous receptors, was coated on the surface of poly(dimethylsiloxane) microchannels. The bilayers contained dinitrophenyl (DNP)-conjugated lipids for binding with bivalent anti-DNP antibodies. Twelve independent data points of surface coverage versus bulk protein concentration could be made simultaneously by forming a linear array of channels and flowing fluorescently labeled antibodies into them. This enabled an entire binding curve to be obtained in a single experiment. The measured apparent binding constant for the DNP/anti-DNP system was 1.8 microM. The methodology for performing heterogeneous assays developed here not only produces rapid results but also requires much less protein than traditional procedures and eliminates some standard sources of experimental error.

Transformations in methane hydrates

Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A and volume V = 5051.3(13) A(3); structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A, c = 9.992(3) A, and V = 1241.9(5) A(3). The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

Elasticity of MgO and a primary pressure scale to 55 GPa

We have studied the elasticity and pressure-density equation of state of MgO in diamond cells to 55 GPa and have doubled the previous pressure limit of accurate elasticity determinations for crystals. Integrating single-crystal velocity data from Brillouin scattering measurements and density data from polycrystalline x-ray diffraction, we obtained the three principal elastic tensor elements (C(11), C(12), and C(44)) and various secondary elasticity parameters, including single-crystal elastic anisotropy, Cauchy relation, aggregate sound velocities, and Poisson's ratio, as functions of pressure. The present study also provides a direct determination of pressure without recourse to any prior pressure standard, thus creating a primary pressure scale. The commonly used ruby fluorescence pressure scale has thus been improved to 1% accuracy by the new MgO scale.

Expression, refolding, and isotopic labeling of human serum albumin domains for NMR spectroscopy

Many different compounds bind to human serum albumin (HSA), which can be a significant problem in the drug discovery process. To aid in the design of drug molecules that do not bind to HSA, the structures of HSA/ligand complexes would be very useful. However, little information has been reported on the structures of small molecules complexed to HSA. In this paper, we describe a procedure for preparing isotopically labeled domains of HSA for nuclear magnetic resonance (NMR) studies. The procedure involves the expression in Escherichia coli, refolding, and a multistep purification. Domains I and III are capable of folding into stable structural units and producing well resolved (15)N/(1)H correlation spectra, whereas domain II forms significant aggregates at sub-millimolar concentration. Using our protocols, isotopically labeled and properly folded domains I and III can be effectively produced in large quantities for NMR-based structural studies and NMR-based screening. This provides a valuable tool for obtaining structural information on HSA/ligand complexes by NMR which will be useful in drug discovery.

Moissanite: a window for high-pressure experiments

We achieved a pressure of 52.1 gigapascals with moissanite anvils, which have optical, thermal, electric, magnetic, and x-ray properties that rival those of diamond. The mode-softening of D(2)O toward the pressure-induced hydrogen bond symmetrization and the Raman shifts of diamond under hydrostatic and nonhydrostatic compressions were studied with moissanite anvils in the spectral regions normally obscured by diamond anvils. Moissanite anvil cells allow maximum sample volumes 1000 times larger than those allowed by diamond anvil cells and may enable the next level of advancement in high-pressure experiments.

[Experimental studies of icariin on anticancer mechanism]

Icariin (ICA) is a kind of new biological respone modifier(BRM) and differentiational agent. In order to further elucidate the reversion of malignant phenotypes of tumor cells and the mechanism of its action, highly metastatic human lung cancer cells(PG) were treated with ICA in vitro. In this study, MTT assay, radioimmune assay, flow cytometry(FCM) and invasion assay were used. The results showed that ICA could influence the distribution of PG cells cycle and reduce S phase. Moreover, ICA increased the level of cAMP in PG cells, reduced the level of cGMP and increased the cAMP/cGMP ratio. On the other hand, ICA decreased PG cells adhesive ratio to laminin substrate and decreased the ability of invasion or migration. These data demonstrate that ICA maybe a kind of effective anticancer drug.

Raman spectroscopy of iron to 152 gigapascals: implications for Earth's inner core

Raman spectra of hexagonal close-packed iron (varepsilon-Fe) have been measured from 15 to 152 gigapascals by using diamond-anvil cells with ultrapure synthetic diamond anvils. The results give a Gruneisen parameter gamma(0) = 1.68 (+/-0.20) and q = 0.7 (+/-0.5). Phenomenological modeling shows that the Raman-active mode can be approximately correlated with an acoustic phonon and thus provides direct information about the high-pressure elastic properties of iron, which have been controversial. In particular, the C(44) elastic modulus is found to be lower than previous determinations. This leads to changes of about 35% at core pressures for shear wave anisotropies.

Conscious and unconscious processing of nonverbal predictability in Wernicke's area

The association of nonverbal predictability and brain activation was examined using functional magnetic resonance imaging in humans. Participants regarded four squares displayed horizontally across a screen and counted the incidence of a particular color. A repeating spatial sequence with varying levels of predictability was embedded within a random color presentation. Both Wernicke's area and its right homolog displayed a negative correlation with temporal predictability, and this effect was independent of individuals' conscious awareness of the sequence. When individuals were made aware of the underlying sequential predictability, a widespread network of cortical regions displayed activity that correlated with the predictability. Conscious processing of predictability resulted in a positive correlation to activity in right prefrontal cortex but a negative correlation in posterior parietal cortex. These results suggest that conscious processing of predictability invokes a large-scale cortical network, but independently of awareness, Wernicke's area processes predictive events in time and may not be exclusively associated with language.

Synthesis of oligonucleotides containing the alkali-labile pyrimidopurinone adduct, M(1)G

An improved method for the synthesis of oligodeoxyribonucleotides containing the endogenous adduct, pyrimido[1,2-a]purin-10(3H)-one (M(1)G), is reported. The key features of the methodology include improved synthesis of the deoxynucleoside of M(1)G by transribosylation with deoxycytidine catalyzed by nucleoside 2'-deoxyribosyltransferase and the use of commercially available 4-tert-butylphenoxyacetyl protecting groups for normal nucleotides. Facile deprotection and removal of the M(1)G-containing oligomers from the solid support were achieved by treatment with a solution of potassium carbonate in methanol. NMR studies were performed to determine the stability of the oligonucleotides at different pHs.

HLA-DRB1 gene polymorphism in patients with dilated cardiomyopathy

To probe into the genetic background and immunopathogenesis of dilated cardiomyopathy (DCM), HLA-DRB1 gene polymorphism in 68 patients with DCM and 175 normal control subjects were analyzed by using the polymerase chain reaction/sequence specific primer (PCR/SSP) techniques. It was found that the frequencies of HLA-DRB1* 15 and HLA-DRB1* 03 alleles were significantly lower in DCM patients than those in normal controls (14.71% vs 29.71% and 4.41% vs 15.43%, respectively), the relative risks (RR) in the DCM patients being 0.41 and 0.25, respectively, all P < 0.05. However, the frequencies of HLA-DRB1* 11 and HLA-DRB1* 12 alleles were significantly higher in the DCM patients than in controls (29.4% vs 12.00% and 36.76% vs 12.57%, respectively) with the RR in the DCM patients being 3.06 and 4.04, respectively, all P < 0.01. These findings further demonstrated that immunogenetics might play a predominant pathogenetic role in partial DCM patients.

Effects of chlorophyll availability on phycobilisomes in Synechocystis sp. PCC 6803

Inactivation of the chlL gene in Synechocystis sp. PCC 6803 resulted in negligible chlorophyll content when the mutant was grown in darkness. Upon phycocyanin excitation at 580 nm, the 77K fluorescence spectrum of dark-grown cells showed three peaks at 648 nm, 665 nm, and 685 nm, this last being the largest. This reflects the functional presence of major components of phycobilisomes, including phycocyanin, allophycocyanin, and the terminal emitter, and efficient energy transfer between these components. As expected, no fluorescence emission peaks corresponding to chlorophyll in the photosystems were observed. Intact phycobilisomes could be isolated from the dark-grown chlL-deletion mutant. However, the phycobilisomes had a lower efficiency of energy transfer than did those isolated from the light-grown mutant, probably because of a decreased phycobilisome stability in the absence of chlorophyll. Exposing the dark-grown chlL-deletion mutant to light triggered the biosynthesis of chlorophyll. For the first 6 h in the light, upon phycocyanin excitation at 580 nm, the 77K fluorescence emission spectrum of greening cells was identical to that of dark-grown cells that lacked significant amounts of chlorophyll. With increased chlorophyll synthesis, gradual energy transfer from phycobilisomes to the two photosystems can be demonstrated.

A novel loop-loop recognition motif in the yeast ribosomal protein L30 autoregulatory RNA complex

The yeast Saccharomyces cerevisiae ribosomal protein L30 negatively autoregulates its production by binding to a helix-loop-helix structure formed in its pre-mRNA and its mRNA. A three-dimensional solution structure of the L30 protein in complex with its regulatory RNA has been solved using NMR spectroscopy. In the complex, the helix-loop-helix RNA adopts a sharply bent conformation at the internal loop region. Unusual RNA features include a purine stack, a reverse Hoogsteen base pair (G11anti-G56syn) and highly distorted backbones. The L30 protein is folded in a three-layer alpha/beta/alpha sandwich topology, and three loops at one end of the sandwich make base-specific contacts with the RNA internal loop. The protein-RNA binding interface is divided into two clusters, including hydrophobic and aromatic stacking interactions centering around G56, and base-specific hydrogen-bonding contacts to A57, G58 and G10-U60 wobble base pair. Both the protein and the RNA exhibit a partially induced fit for binding, where loops in the protein and the internal loop in the RNA become more ordered upon complex formation. The specific interactions formed between loops on L30 and the internal loop on the mRNA constitute a novel loop-loop recognition motif where an intimate RNA-protein interface is formed between regions on both molecules that lack regular secondary structure.

Thermal conformational changes of bovine fibrinogen by differential scanning calorimetry and circular dichroism

The thermal denaturation of bovine fibrinogen has been investigated using differential scanning calorimetry (DSC) and circular dichroism (CD) spectroscopy. Differential scanning calorimetry measurements were carried out while changing the scan-rate. The transition at 57 degrees C was found to be irreversible and highly scan-rate dependent, suggesting that the denaturation is, at least in part, under kinetic control. The secondary structural changes at various temperatures were monitored by far-ultraviolet CD spectroscopy. These results show that the DSC transition for the thermal denaturation of bovine fibrinogen can be interpreted in terms of a kinetic process, N --> F, where k is a first-order kinetic constant that changes with temperature according to the Arrhenius equation. An important transition peak was observed at 78.8 degrees C which is attributed to the C-terminal parts of the Aalpha chains of fibrinogen.

Assignment of the L30-mRNA complex using selective isotopic labeling and RNA mutants

The helix-loop-helix structure formed in the pre-mRNA and the mRNA of L30, a ribosomal protein from the yeast Saccharomyces cerevisiae, serves as an auto-regulatory binding site for the protein to suppress the L30 synthesis upon overproduction. Using a 33-nucleotide model RNA, the structures of the L30 binding site RNA in the presence and absence of the protein were investigated using nuclear magnetic resonance (NMR) spectroscopy. Homonuclear and(13)C/(15)N-based resonance assignments and spectral comparisons indicated that the purine-rich internal loop is dynamic in the free RNA but becomes ordered in the presence of L30 protein. Although the resonances in the loop region are sharper and more disperse in the bound RNA, their assignment was extremely challenging, due to spectral complexity and broadened resonances caused by local dynamics. Two strategies, namely selective(13)C/(15)N-labeling and NMR analyses of five complexes with RNA mutants, were used to overcome these difficulties. Only using these approaches could assignment of the internal loop resonances and identification of the unusual NOEs and nucleotide conformations within the internal loop be made. In the case of structural determination of the L30-mRNA complex, it was critical to be able to take advantage of the available biochemical information in order to complete the structure determination.

Solution structure of an oligodeoxynucleotide containing the malondialdehyde deoxyguanosine adduct N2-(3-oxo-1-propenyl)-dG (ring-opened M1G) positioned in a (CpG)3 frameshift hotspot of the Salmonella typhimurium hisD3052 gene

The refined solution structure for the ring-opened N2-(3-oxo-1-propenyl)-dG derivative of the malondialdehyde deoxyguanosine adduct M(1)G [3-(2'-deoxy-beta-D-erythro-pentofuranosyl)pyrimido[1, 2-a]purin-10(3H)-one] in d(ATCGCXCGGCATG) x d(CATGCCGCGCGAT) [X being N(2)-(3-oxo-1-propenyl)-dG], containing the d(CpG)(3) frameshift hotspot of the Salmonella typhimurium hisD3052 gene, is presented. When inserted into this duplex, M(1)G underwent spontaneous ring opening to N2-(3-oxo-1-propenyl)-dG. NMR analysis revealed that N2-(3-oxo-1-propenyl)-dG induced minor structural perturbations in the hisD3052 oligodeoxynucleotide. However, the stability of the duplex DNA was reduced; the N2-(3-oxo-1-propenyl)-dG-modified hisD3052 oligodeoxynucleotide exhibited a 14 degrees C decrease in T(m) relative to that of the native oligodeoxynucleotide. The modified guanine maintained stacking interactions with neighboring bases but was not Watson-Crick hydrogen bonded. A total of 13 NOEs were observed from the 3-oxo-1-propenyl moiety protons of N2-(3-oxo-1-propenyl)-dG to DNA protons. Molecular dynamics calculations, restrained by 602 distance restraints derived from experimental NOE measurements and 23 empirical distance restraints, converged with pairwise rmsd differences of <0.90 A. The sixth-root residual factor with the NMR data was 9.1 x 10(-2). The cytosine complementary to N2-(3-oxo-1-propenyl)-dG was pushed toward the major groove but maintained partial stacking interactions with its neighboring bases. The modified guanine remained in the anti conformation, while the 3-oxo-1-propenyl moiety was positioned in the minor groove of the duplex. Possible correlations between the relatively small structural perturbations induced in this DNA duplex by N2-(3-oxo-1-propenyl)-dG and the mutagenic spectrum of M(1)G are discussed.

A confrontational naming task produces congruent increases and decreases in PET and fMRI

This work uses the well-established (by PET) confrontation naming task to compare PET and fMRI in a cognitive activation experiment. The signal changes from this task are much less than the changes caused by visual or motor activation tasks used in previous comparisons. ANOVA methods adjusted for multiple comparisons were used to determine significant changes in signal between confrontation naming and figure size discrimination tasks. All 17 significantly increased regions (confrontation naming signal greater) seen on one modality were increased on both modalities. Ten of 13 regions that were significantly decreased on one modality were decreased on the other. Three mismatched regions showed a significant decrease on one modality and a nonsignificant increase on the other. This study could not detect a consistent difference in activation site location between PET and fMRI.

Segmented spin-echo pulses to increase fMRI signal: repeated intrinsic diffusional enhancement

Since its inception, functional magnetic resonance imaging (fMRI) has seen rapid progress in the application to neuroscience. Common gradient-recalled acquisition methods are susceptible to static field inhomogeneities, resulting in signal loss at the medial temporal area important for memory function or at the basal ganglia area for motor control. In addition, they are susceptible to the contaminating signals of large vein origin, such as the signals from its surrounding cerebrospinal fluid (CSF) leading to false-positive activation. Spin echoes overcome these drawbacks. However, they are less sensitive to blood oxygenation level dependent (BOLD) susceptibility changes because of their refocusing mechanism. A method is presented here to enhance the spin-echo fMRI signal by recruiting more spins to participate in the dynamic BOLD process. This method divided a conventional T(2) weighting period into several segments separated by blocks of extra free diffusion time. Before the extra diffusion time spins are restored to the longitudinal axis preventing rapid transverse relaxation. This process allows more spin access to the regions that experience the BOLD field gradient. Because of the increased spin population that is modulated by the capillary BOLD field gradient, the functional signal is increased. Spin-echo echo-planar imaging (EPI) with this enhancement may be a useful technique for fMRI studies at inhomogeneous areas such as the air/tissue interface. Magn Reson Med 42:631-635, 1999.

Local folding coupled to RNA binding in the yeast ribosomal protein L30

The ribosomal protein L30 from yeast Saccharomyces cerevisiae auto-regulates its own synthesis by binding to a structural element in both its pre-mRNA and its mRNA. The three-dimensional structures of L30 in the free (f L30) and the pre-mRNA bound (b L30) forms have been solved by nuclear magnetic resonance spectroscopy. Both protein structures contain four alternating alpha-helices and four beta-strands segments and adopt an overall topology that is an alphabetaalpha three-layer sandwich, representing a unique fold. Three loops on one end of the alphabetaalpha sandwich have been mapped as the RNA binding site on the basis of structural comparison, chemical shift perturbation and the inter-molecular nuclear Overhauser effects to the RNA. The structural and dynamic comparison of f L30 and b L30 reveals that local dynamics may play an important role in the RNA binding. The fourth helix in b L30 is longer than in f L30, and is stabilized by RNA binding. The exposed hydrophobic surface that is buried upon RNA binding may provide the energy necessary to drive secondary structure formation, and may account for the increased stability of b L30.

Continuous functional magnetic resonance imaging reveals dynamic nonlinearities of "dose-response" curves for finger opposition

Linear experimental designs have dominated the field of functional neuroimaging, but although successful at mapping regions of relative brain activation, the technique assumes that both cognition and brain activation are linear processes. To test these assumptions, we performed a continuous functional magnetic resonance imaging (MRI) experiment of finger opposition. Subjects performed a visually paced bimanual finger-tapping task. The frequency of finger tapping was continuously varied between 1 and 5 Hz, without any rest blocks. After continuous acquisition of fMRI images, the task-related brain regions were identified with independent components analysis (ICA). When the time courses of the task-related components were plotted against tapping frequency, nonlinear "dose- response" curves were obtained for most subjects. Nonlinearities appeared in both the static and dynamic sense, with hysteresis being prominent in several subjects. The ICA decomposition also demonstrated the spatial dynamics with different components active at different times. These results suggest that the brain response to tapping frequency does not scale linearly, and that it is history-dependent even after accounting for the hemodynamic response function. This implies that finger tapping, as measured with fMRI, is a nonstationary process. When analyzed with a conventional general linear model, a strong correlation to tapping frequency was identified, but the spatiotemporal dynamics were not apparent.

Duplex DNA catalyzes the chemical rearrangement of a malondialdehyde deoxyguanosine adduct

The primary DNA lesion induced by malondialdehyde, a byproduct of lipid peroxidation and prostaglandin synthesis, is 3-(2'-deoxy-beta-D-erythro-pentofuranosyl)-pyrimido[1, 2-a]purin-10(3H)-one (M1G). When placed opposite cytosine (underlined) at neutral pH in either the d(GGTMTCCG).d(CGGACACC) or d(ATCGCMCGGCATG). d(CATGCCGCGCGAT) duplexes, M1G spontaneously and quantitatively converts to the ring-opened derivative N2-(3-oxo-1-propenyl)-dG. Ring-opening is reversible on thermal denaturation. Ring-opening does not occur at neutral pH in single-stranded oligodeoxynucleotides or when T is placed opposite to M1G in a duplex. The presence of a complementary cytosine is not required to stabilize N2-(3-oxo-1-propenyl)-dG in duplex DNA at neutral pH. When N2-(3-oxo-1-propenyl)-dG is placed opposite to thymine in a duplex, it does not revert to M1G. A mechanism for the conversion of M1G to N2-(3-oxo-1-propenyl)-dG is proposed in which the exocyclic amino group of the complementary cytosine attacks the C8 position of the M1G exocyclic ring and facilitates ring opening via formation of a transient Schiff base. Addition of water to the Schiff base regenerates the catalytic cytosine and generates N2-(3-oxo-1-propenyl)-dG. These results document the ability of duplex DNA to catalyze the transformation of one adduct into another, which may have important consequences for mutagenesis and repair.

Intrastrain variants of herpes simplex virus type 1 isolated from a neonate with fatal disseminated infection differ in the ICP34.5 gene, glycoprotein processing, and neuroinvasiveness

Two intrastrain variants of herpes simplex virus type 1 (HSV-1) were isolated from a newborn with fatal disseminated infection. A small-plaque-producing variant (SP7) was the predominant virus (>99%) in the brain, and a large-plaque-producing variant (LP5) was the predominant virus (>99%) in the lung and gastrointestinal tract. EcoRI and BamHI restriction fragment patterns indicated that SP7 and LP5 are related strains. The large-plaque variants produced plaques similar in size to those produced by HSV-1 KOS. Unlike LP5 or KOS, SP7 was highly cell associated and processing of glycoprotein C and glycoprotein D was limited to precursor forms in infected Vero cells. The large-plaque phenotype from KOS could be transferred into SP7 by cotransfection of plasmids containing the EK or JK EcoRI fragment or a 3-kb plasmid with the UL34.5 gene of HSV-1 KOS together with SP7 DNA. PCR analysis using primers from within the ICP34.5 gene indicated differences for SP7, LP5, and KOS. Sequencing data indicated two sets of deletions in the UL34.5 gene that distinguish SP7 from LP5. Both SP7 and LP5 variants were neurovirulent (lethal following intracranial inoculation of young BALB/c mice); however, the LP5 variant was much less able to cause lethal neuroinvasive disease (footpad inoculation) whereas KOS caused no disease. Passage of SP7 selected for viruses (SLP-5 and SLP-10) which were attenuated for lethal neuroinvasive disease, were not cell-associated, and differed in the UL34.5 gene. UL34.5 from SLP-5 or SLP-10 resembled that of KOS. These findings support a role for UL34.5 in promoting virus egress and for neuroinvasive disease.

Intercalation of the (-)-(1R,2S,3R, 4S)-N6-[1-benz[a]anthracenyl]-2'-deoxyadenosyl adduct in an oligodeoxynucleotide containing the human N-ras codon 61 sequence

The solution structure of the (-)-(1R,2S,3R,4S)-N6-[1-(1,2,3, 4-tetrahydroxy-benz[a]anthracenyl)]-2'-deoxyadenosyl adduct at X6 of 5'-d(CGGACXAGAAG)-3'.5'-d(CTTCTTGTCCG)-3', incorporating codons 60, 61(italic), and 62 of the human N-ras protooncogene, was determined. This adduct results from the trans opening of 1S,2R,3R,4S-1, 2-epoxy-1,2,3,4-tetrahydro-benz[a]anthracenyl-3,4-diol by the exocyclic N6 of adenine. Molecular dynamics simulations were restrained by 509 NOEs from 1H NMR. The precision of the refined structures was monitored by pairwise root-mean-square deviations which were <1.2 A; accuracy was measured by complete relaxation matrix calculations, which yielded a sixth root R factor of 9.1 x 10(-)2 at 250 ms. The refined structure was a right-handed duplex, in which the benz[a]anthracene moiety intercalated from the major groove between C5.G18 and R,S,R,SA6.T17. In this orientation, the saturated ring of BA was oriented in the major groove of the duplex, with the aromatic rings inserted into the duplex such that the terminal ring of BA threaded the duplex and faced toward the minor groove direction. The duplex suffered localized distortion at and immediately adjacent to the adduct site, evidenced by the increased rise of 8.8 A as compared to the value of 3.5 A normally observed for B-DNA between base pairs C5.G18 and R,S,R,SA6.T17. These two base pairs also buckled in opposite directions away from the intercalated BA moiety. The refined structure was similar to the (-)-(7S,8R,9S,10R)-N6-[10-(7,8,9, 10)-tetrahydrobenzo[a]pyrenyl)]-2'-deoxyadenosyl adduct of corresponding stereochemistry at X6 of the same oligodeoxynucleotide [Zegar, I. S., Kim, S. J., Johansen, T. N., Horton, P. J., Harris, C. M., Harris, T. M., and Stone, M. P. (1996) Biochemistry 35, 6212-6224]. Both adducts intercalated toward the 5'-direction from the site of adduction. The similarities in solution structures were reflected in similar biological responses, when repair-deficient AB2480 Escherichia coli were transformed with M13mp7L2 DNA site-specifically modified with these two adducts.

Immunization with a LEAPS heteroconjugate containing a CTL epitope and a peptide from beta-2-microglobulin elicits a protective and DTH response to herpes simplex virus type 1

A ligand epitope antigen presentation system (LEAPS) heteroconjugate vaccine containing a CTL epitope (H1) from the HSV-1 immediate early protein ICP27 (322-332) and a peptide sequence (J) from beta-2-microglobulin (35-50) elicited protection from intraperitoneal viral challenge and promoted DTH responses. The H1 peptide and other H1 containing heteroconjugates did not elicit protection or DTH responses. Antibody to the H1 peptide could not be detected by ELISA following vaccination with peptide, heteroconjugate or natural infection. The LEAPS heteroconjugate appears to prime a Thl-like response which is subsequently boosted by infection. These studies show that attachment of the J peptide can make a CTL epitope into a vaccine which is immunogenic and promotes a protective Th1 type of response.

[An experimental study of viscoelastic properties of articular-cartilage of patella]

OBJECTIVE

To study the viscoelastic properties of human articular cartilages of patella in 8 cadavers, which were obtained from patients ranged in age from nineteen to fifty-one years old and died of acute head injury.

METHODS

The creep and stress relaxation of articular cartilage of patella were abserved in the condition of articular cartilage loaded of 500 Pa, just as the physiological load of articular cartilage of patella in keeping human body standing position with the knee joint flexed 30 degrees, during the experiment. The deformation-time curve under certain load, the load-time curve under certain deformity and related data were obtained.

RESULTS

Creep and stress relaxation showed that obvious changes occured in the first 10-15 minutes during the whole process.

CONCLUSIONS

The data and curve will not only be helpful to understand the pathogenesis of chondromalacia, but also propose a feasible method to study it from biomechanical view, meanwhile provide reference data for designing the prosthesis of patella and material choosing.

[Influence of icariin on cell membrane of highly metastatic human lung tumor cell line]

In this study, flow cytometry (FCM) and fluorescent probe technique were used to explore the influence of icariin (ICA) on cell membrane of PG. The data suggested that ICA could inhance membrane fluidity of PG and increase the expression of membrane HLA-ABC antigen. This could be one of the anticancer mechanisms of ICA.

Profile of the ecdysteroid hormone and its receptor in the salivary gland of the adult female tick, Amblyomma hebraeum

We examined the hemolymph ecdysteroid titer (by radioimmunoassay) and profile of the ecdysteroid receptor (EcR/USP; by [3H]ponasterone A binding, gel mobility shift assay, Western blot) in the salivary gland of the ixodid tick, Amblyomma hebraeum Koch (Acari: Ixodidae) throughout the tick feeding period and first 6 days post-engorgement. Throughout the slow phase of feeding, the hemolymph ecdysteroid titer was approximately 18 pg/microliter. The titer peaked at approximately 52 pg/microliter during the rapid phase of feeding, falling back to approximately 22 pg/microliter on the day of engorgement. Ecdysteroid titer rose again to approximately 750 pg/microliter by day 6 post-engorgement. EcR was undetectable by any of the three assays in unfed ticks. Following the onset of feeding, there appeared both specific ponasterone A binding and two major EcR bands detected by Western blot analysis. Both measurements were sustained throughout the feeding period, but declined after detachment when the salivary glands were degenerating. After ticks reached about 100 mg (by which time most females are mated), a discrete DNA-binding band was shown by gel mobility shift assay using Drosophila hsp27 EcRE as a probe. Moreover, the band intensified when hemolymph ecdysteroid titer reached its peak during the rapid phase of feeding; it declined along with decreasing EcR/USP levels, and with specific ligand binding activity following engorgement. This study suggests a role for the small hemolymph ecdysteroid peak during the rapid phase of feeding in initiating salivary gland degeneration.