Deregulated expression of Notch receptors in human hepatocellular carcinoma

BACKGROUND AND AIM

Notch signaling controls cellular differentiation and proliferation. Deregulated expression of Notch receptors is observed in a growing number of malignant tumours, however, the role of Notch signaling in hepatocellular carcinoma is still unknown. To address this, the expression of Notch receptors in human hepatocellular carcinoma was examined in both protein and ribonucleic acid levels.

PATIENTS AND METHODS

Fifty-three hepatocellular carcinoma tissue sections were detected by immunohistochemistry. Three paired fresh surgical hepatocellular carcinoma and adjacent nontumour liver samples were analyzed by Western blot and reverse transcriptase polymerase chain reaction. Immunohistochemistry, Western blot and reverse transcriptase polymerase chain reaction are reliable methods to examine the expression of protein and RNA.

RESULTS

All of the four Notch receptors were expressed in the neoplastic cells of hepatocellular carcinoma tissues with different intensity and extensity. Notch1 and Notch4 were expressed in both cytoplasm and nucleus, and all of the nuclear staining showed up in the cytoplasm-positive cases. Cytoplasmic and nuclear Notch1 was detected in 88.7% (47/53) and 9.4% (5/53) of hepatocellular carcinoma tissues, respectively; positive rates of Notch4 were 67.9% (36/53) in cytoplasm and 52.8% (31/53) in nucleus. Notch2 and Notch3 were only in cytoplasm, with positive rates of 26.4% (14/53) and 52.8% (28/53), respectively. Compared with adjacent nontumour liver, Notch1 (cytoplasmic) and Notch4 (nuclear) were up-regulated (P<0.05, P<0.05), Notch2 was down-regulated (P<0.05), while Notch1 (nuclear), Notch3 and Notch4 (cytoplasmic) showed no difference between hepatocellular carcinoma and adjacent nontumour liver. Western blot and reverse transcriptase polymerase chain reaction analysis showed a consistent result.

CONCLUSION

Our findings indicate that the expression of Notch receptors was deregulated and Notch signaling might be involved in the development of hepatocellular carcinoma.

Induction of apoptosis in HepG2 cells by solanine and Bcl-2 protein

The nightshade (Solanum nigrum Linn.) has been widely used in Chinese traditional medicine as a remedy for the treatment of digestive system cancer. The anti-tumor activity of solanine, a steroid alkaloid isolated from the nightshade has been demonstrated. To observe the effect of anti-tumor and mechanism of solanine. The MTT assay was used to evaluate the IC(50) on the three digestive system tumor cell lines. The effect on the morphology was observed with a laser confocal microscopy; the rate of apoptosis and the cell cycle were measured using flow cytometry (FCM); the expression of Bcl-2 protein was measured by Western blot. The results show that the IC(50) for HepG(2), SGC-7901, and LS-174 were 14.47, >50, and >50 microg/ml, respectively; the morphology of cells in the negative control was normal; for the treated groups, typical signs for apoptosis were found. The rate of apoptosis in HepG(2) cells induced by solanine was found to be 6.0, 14.4, 17.3, 18.9, and 32.2%, respectively. Observation of the cell cycle showed that cells in the G(2)/M phases disappeared while the number of cells in the S phase increased significantly for treated groups. Western blot showed that solanine decreased the expression of Bcl-2 protein. Therefore, the target of solanine in inducing apoptosis in HepG(2) cells seems to be mediated by the inhibition in the expression of Bcl-2 protein.

[Reversal of multidrug resistance of gastric cancer cells by down-regulation of CIAPIN1 with CIAPIN1 siRNA]

The overexpression of a new cytokine-induced apoptosis inhibitor 1 (CIAPIN1) gene has been shown previously to promote a multidrug resistant phenotype in gastric cancer cells through the upregulation of MDR1 and MRP1. In the present study, we constructed the siRNA eukaryotic expression vectors of CIAPIN1 and transfected them into SGC7901/VCR cells to examine whether the down regulation of CIAPIN1 increased cell sensitivity towards chemotherapeutic drugs. After transfection, the expression of CIAPIN1 was dramatically decreased in CIAPIN1 siRNA transfectants compared with that in parental cells and empty vector control cells. The down-regulation of CIAPIN1 significantly enhanced the sensitivity of SGC7901/VCR cells to vincristine (VCR), adriamycin (ADR) and etoposide (VP-16), but not to 5-fluorouracil (5-FU) and cisplatin (CDDP). Cell capacity to efflux adriamycin decreased markedly in CIAPIN1 siRNA transfectants, and correlation between CIAPIN1 down regulation and decreased MDR1 transcriptional activity were observed. CIAPIN1 siRNA could significantly down regulate the expression of Bcl-2, and up-regulate the expression of Bax, but not alter the expression of PTEN in gastric cancer cells. These observations suggested that the siRNA constructs of CIAPIN1 we obtained could effectively down-regulate the expression of CIAPIN1 and reverse the resistant phenotype of gastric cancer cells. The further study of the biological functions of CIAPIN1 may be helpful for understanding the mechanisms of multidrug resistance of gastric cancer and developing possible strategies to treat gastric cancer.

Spot urine protein/creatinine ratios are unreliable estimates of 24 h proteinuria in most systemic lupus erythematosus nephritis flares

The diagnosis of glomerulonephritis flares in systemic lupus erythematosus (SLE) is usually based on whether the magnitude of proteinuria has changed. Our study tests two methods to assess proteinuric change: protein/creatinine (P/C) ratios of intended 24-h urine collections or that of spot urine samples. Sixty-four patients with glomerulonephritis due to SLE followed in the Ohio SLE Study provided bimonthly paired spot and intended 24-h urine collections. Completeness of each collection was estimated as the ratio of the measured creatinine to the expected creatinine based upon Cockroft-Gault. Intended 24-h urine collections with measured/expected creatinine ratios between 0.5 and 0.9 (237 samples overall) showed ratios that were not significantly different from ratios of complete 24-h urine collections with ratios of 0.9-1.1 (159 samples). To compare spot and 24 h P/C ratios, we randomly selected pairs of samples with measured/expected ratios above 0.75. Consistent with previous studies, spot and 24-h urine P/C ratios showed good correlation over the range of values as well as reasonably strong concordance. Over the range of most SLE glomerulonephritis flares, however, correlation was present but concordance was poor. Our work suggests that the use of spot urine P/C ratios will yield more false-positive and -negative diagnoses of glomerulonephritis flares in patients with SLE than the ratio in 24-h urines.

Bone nanostructure near titanium and porous tantalum implants studied by scanning small angle x-ray scattering

Bone sections including either titanium or porous tantalum implant devices used for interbody spinal fusion were investigated with position-resolved small angle X-ray scattering (sSAXS). The samples were obtained from six-month-old pigs that had undergone surgery three months prior to sacrifice. The aim of the study was to explore the possibility of using sSAXS to obtain information about thickness, orientation and shape/arrangement of the mineral crystals in bone near the implant surfaces. Detailed sSAXS scans were carried out in two different regions of bone adjacent to the implant in each of the implant samples. In the implant vicinity the mineral crystals tended to be aligned with the surface of the implants. The mean crystal thickness was between 2.1 and 3.0 nm. The mineral crystal thickness increased linearly with distance from the implant in both regions of the porous tantalum implant and in one of the regions in the titanium sample. In the second region of the titanium sample the thickest mineral crystals were found close to the implant surface. The observed differences in mineral thickness with distance from the implant surfaces might be explained by differences in mechanical load induced by the implant material and the geometrical design of the implant. The study shows that sSAXS is a powerful tool to characterize the nanostructure of bone near implant surfaces.

The study of peripheral blood mononuclear cell MHC I and MHC II gene mRNA expression in acute graft rejection

BACKGROUND

Early diagnosis of acute graft rejection is important in the clinic. To explore a reliable diagnostic marker, we selected skin-grafted rabbits as an animal model to study peripheral blood mononuclear cell (PBMC) major histocompatibility complex 1 (MHC I) and MHC II gene mRNA in acute graft rejection (AGR).

METHODS

Fifteen New Zealand white rabbits were randomly divided into three groups to observe skin graft rejection: three rabbits were in the autograft control group; six rabbits in a cyclosporine (CsA) treated allografted group; and the other six rabbits in untreated allografted group. The CsA-treated allografted group was given CsA (5 mg/kg) daily intramuscularly. PBMC samples were obtained every 2 days to detect by real-time polymerase chain reaction, PBMC MHC I and MHC II gene mRNA.

RESULTS

MHC I and MHC II gene mRNA levels did not show any obvious change in the autografted controls. MHC I gene mRNA levels showed a slow increase in the CsA-treated allografted group, but no obvious change in the untreated allografted group. MHC II gene mRNA reached the highest level at 2 to 3 days before graft rejection appeared macroscopically in the CsA-treated allografted group and untreated allografted group, then decreasing to a low level.

CONCLUSION

Compared with MHC I gene mRNA expression, PBMC MHC II gene mRNA expression may be considered to be an earlier marker for AGR.

L-carnitine protects neurons from 1-methyl-4-phenylpyridinium-induced neuronal apoptosis in rat forebrain culture

1-Methyl-4-phenylpyridinium ion (MPP+), an inhibitor of mitochondrial complex I, has been widely used as a neurotoxin because it elicits a severe Parkinson's disease-like syndrome with an elevation of intracellular reactive oxygen species (ROS) and apoptosis. L-carnitine plays an integral role in attenuating the brain injury associated with mitochondrial neurodegenerative disorders. The present study investigates the effects of L-carnitine against the toxicity of MPP+ in rat forebrain primary cultures. Cells in culture were treated for 24 h with 100, 250, 500 and 1000 microM MPP+ alone or co-incubated with L-carnitine. MPP+ produced a dose-related increase in DNA fragmentation as measured by cell death ELISA (enzyme-linked immunosorbent assay), an increase in the number of TUNEL (terminal dUTP nick-end labeling)-positive cells and a reduction in the mitochondrial metabolism of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). No significant effect was observed with the release of lactate dehydrogenase (LDH), indicating that cell death presumably occurred via apoptotic mechanisms. Co-incubation of MPP+ with L-carnitine significantly reduced MPP+-induced apoptosis. Western blot analyses showed that neurotoxic concentrations of MPP+ decreased the ratio of BCL-X(L) to Bax and decreased the protein levels of polysialic acid neural cell adhesion molecules (PSA-NCAM), a neuron specific marker. L-carnitine blocked these effects of MPP+ suggesting its potential therapeutic utility in degenerative disorders such as Parkinson's disease, Alzheimer's disease, ornithine transcarbamylase deficiency and other mitochondrial diseases.

Involvement of peripheral neuropeptide y receptors in sympathetic modulation of acute cutaneous flare induced by intradermal capsaicin

In a recent study, we have demonstrated that the dorsal root reflex (DRR)-mediated acute cutaneous neurogenic inflammation following intradermal injection of capsaicin (CAP) is sympathetically dependent and subject to modulation by peripheral alpha(1)-adrenoceptors. Postganglionic sympathetic neurons contain not only adrenergic neurotransmitters, but also non-adrenergic substances, including neuropeptide Y (NPY). In this study, we examined if peripheral NPY receptors participate in the flare following CAP injection. Different NPY receptor subtypes were studied by using relatively specific agonists and antagonists for the Y(1) and Y(2) subtypes. Changes in cutaneous blood flow on the plantar surface of the foot were measured using a laser Doppler flowmeter. Following CAP injection, cutaneous flare spread more than 20 mm away from the site of CAP injection. Removal of the postganglionic sympathetic nerves by surgical sympathectomy reduced dramatically the CAP-evoked flare. If the foot of sympathectomized rats was pretreated with either NPY or Y(2) receptor agonists by intra-arterial injection, the spread of flare induced by CAP injection could be restored and prolonged. However, if the spinal cord was pretreated with a GABA(A) receptor antagonist, bicuculline, to prevent DRRs, NPY or an Y(2) receptor agonist no longer restored the CAP-evoked flare. A Y(1) receptor agonist did not affect the CAP-evoked flare in sympathectomized rats. In sympathetically intact rats, blockade of either peripheral NPY or Y(2) receptors with [D-Trp(32)]-NPY or BIIE0246 markedly reduced the flare induced by CAP injection, whereas blockade of peripheral Y(1) receptors by BIBP3226 did not obviously affect the flare. It is suggested that NPY is co-released with NE from the postganglionic sympathetic terminals to activate NPY Y(2) and alpha(1) receptors following CAP injection. Both substances are involved, at least in part, in modulation of the responses of CAP sensitive afferents thereby affecting their ability to evoke the release of inflammatory agents from primary afferents.

Role of protein kinase A in phosphorylation of NMDA receptor 1 subunits in dorsal horn and spinothalamic tract neurons after intradermal injection of capsaicin in rats

Protein phosphorylation is a major mechanism for regulation of N-methyl-D-aspartate (NMDA) receptor function. The NMDA receptor 1 subunit (NR1) is phosphorylated by protein kinase A (PKA) on serine 890 and 897. We have recently reported that there is enhanced phosphorylation of NR1 on serine 897 in dorsal horn and spinothalamic tract (STT) neurons after intradermal injection of capsaicin (CAP) in rats [Zou et al. (2000) J. Neurosci. 20, 6989-6997]. Whether or not this phosphorylation, which develops during central sensitization following CAP injection, is mediated by PKA remains to be determined. In this study, western blots and immunofluorescence staining were employed to observe if pretreatment with a PKA inhibitor, N-[2-((p-bromocinnamyl)amino)ethyl]-5-isoquinolinesulfonamide, HCl (H89), blocks the enhanced phosphorylation of NR1 on serine 897 following injection of CAP into the glabrous skin of one hind paw of anesthetized rats. Western blots showed that pretreatment with H89 caused a decrease in CAP-induced phosphorylation of NR1 protein in spinal cord segments L(4)-S(1). In experiments using immunofluorescence staining, the numbers of phospho-NR1-like immunoreactive (p-NR1-LI) neurons seen after CAP injection were significantly decreased in the dorsal horn of the L(4)-L(5) segments on the side ipsilateral to the injection after PKA was inhibited. When STT cells were labeled by microinjection of the retrograde tracer, fluorogold, we found that the proportion of p-NR1-LI STT cells on the side ipsilateral to the injection in the superficial laminae of spinal cord segments L(4)-L(5) was markedly reduced when H89 was administered intrathecally before CAP injection. However, the proportion of p-NR1-LI STT cells in deep laminae was unchanged unless the PKC inhibitor, chelerythrine chloride, was co-administered with H89. Combined with our previous findings, the present results indicate that NR1 in spinal dorsal horn neurons, including the superficial dorsal horn STT cells, is phosphorylated following CAP injection and that this phosphorylation is due to the action of PKA. However, the phosphorylation of deep STT cells involves both PKA and PKC.

Production of antigen-specific human monoclonal antibodies: comparison of mice carrying IgH/kappa or IgH/kappa/lambda transloci

Here we compare human monoclonal antibody (MAb) production from mouse strains that carry disruptions of their endogenous mouse IgH/IgK loci and harbor human IgM + Igkappa(BABkappa) or human IgM + Igkappa + IgA transloci (BABkappa,lambda). We found that whereas both strains proved effective for the isolation of antigen-specific IgM antibodies, many of the IgM MAbs elicited from BABkappa comprise human mu chains that are associated with mouse lambda chains. In contrast, BABkappa,lambda mice gave rise to fully functional, polymeric human IgM antibodies comprising both human IgH and human IgL chains. Therefore, the inclusion of a human Iglambda translocus (in addition to the human IgH + Igkappa transloci) not only diminishes problems of endogenous mouse Iglambda expression but also provides a strain of mice that yields fully human MAbs to a wide range of antigens, as witnessed by the isolation of MAbs to human blood cells, tumor cell lines, and an immunoglobulin idiotype.

Production of cloned goats from enucleated oocytes injected with cumulus cell nuclei or fused with cumulus cells

This study was designed to produce cloned goats from cumulus cells. Cloning donor nuclei were from cumulus cells either freshly isolated or cultured in vitro. Enucleated oocytes were either injected with cumulus cell nuclei without piezo-driven manipulator (injection method) or fused with cumulus cells (fusion method). The survival rate of cloned embryos, obtained by injection, was higher than that derived from fusion (62.7 and 45.9%, respectively). Two cloned goats were derived by fusion with in vitro cultured cumulus cells without starvation, but died shortly after natural birth, from respiratory difficulties. Their birth weights (2.23 kg and 2.03 kg) were within the normal range (2.0-2.7 kg) and postmortem analysis revealed no morphological abnormalities. The third cloned goat, derived by injection of nuclei from freshly isolated cumulus cells, weighed 3.3 kg at birth, and was 37% overweight compared with the average weight of the same species. This goat is healthy and well as this paper is being prepared. Nested PCR-RFLP analysis confirmed that all the cloned goats were derived from the donor cells.

NMDA or non-NMDA receptor antagonists attenuate increased Fos expression in spinal dorsal horn GABAergic neurons after intradermal injection of capsaicin in rats

GABAergic neurons play an important role in the generation of primary afferent depolarization, which results in presynaptic inhibition and, if large enough, triggers dorsal root reflexes. Recent electrophysiological studies by our group have suggested that increased excitation of spinal GABAergic neurons by activation of N-methyl-D-aspartate (NMDA) and non-NMDA receptors following intradermal injection of capsaicin results in the generation of DRRs that contribute to neurogenic inflammation. The present study was to determine if changes in the expression of Fos protein occur in GABAergic neurons in the lumbosacral spinal cord following injection of capsaicin into the glabrous skin of one hind paw of anesthetized rats and if pretreatment with an NMDA receptor antagonist, D-(-)-2-amino-7-phosphonoheptanoic acid (AP7) or a non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) blocks Fos expression in these neurons. The experiments used western blots and immunofluorescence double labeling staining following capsaicin or vehicle injection. Western blots showed that Fos protein was increased on the ipsilateral side in spinal cord tissue 0.5 h after capsaicin injection. Pretreatment with AP7 or CNQX caused a decrease in capsaicin-induced Fos expression. Immunofluorescence double labeling showed that the proportion of Fos-positive GABAergic neuronal profiles was significantly increased following capsaicin injection (48.8+/-4.8%) compared to the vehicle injection (23.8+/-5.1%) in superficial laminae on the ipsilateral side in lumbosacral spinal cord (P<0.05). However, when the spinal cord was pretreated with AP7 (5 microg) or CNQX (0.2 microg), only 9.1+/-0.6% or 7.1+/-0.8% of GABA-immunoreactive neuronal profiles were stained for Fos following capsaicin injection. The blockade of the capsaicin-evoked Fos staining was dose-dependent. These findings suggest that GABAergic neurons take part in dorsal horn circuits that modulate nociceptive information and that the function of GABAergic neurons following capsaicin injection is partially mediated by NMDA and non-NMDA receptors.

Truncation of the mu heavy chain alters BCR signalling and allows recruitment of CD5+ B cells

Ig are multifunctional molecules with distinct properties assigned to individual domains. To assess the importance of IgM domain assembly in B cell development we generated two transgenic mouse lines with truncated muH chains by homologous integration of the neomycin resistance gene (neo(r)) into exons C(mu)1 and C(mu)2. Upon DNA rearrangement shortened muH chain transcripts, V(H)-D-J(H)-C(mu)3-C(mu)4, are produced independent of the transcriptional orientation and termination signals provided by neo(r). The truncated muH chain of approximately 52 kDa associates non-covalently with the L chain to form a monovalent HL heterodimer. Surface IgM is assembled into a defective BCR complex which has lost important signalling capacity. In immunizations with T-dependent and T-independent antigens, specific IgM antibodies cannot be detected, whilst IgG responses remain normal. B cell development in the bone marrow is characterized by an increase in early B cells, but a decrease of B220(+) cells from the stage when muH chain rearrangement is completed. The peritoneal lymphocyte population has elevated levels of CD5(+) B cells and their expansion may be the result of a negative feedback mechanism. The results show that antigenic stimulation is compromised by truncated monovalent IgM and that this deficit in stimulation leads to reduced levels of conventional B-2 lymphocytes, but dramatically increased levels of B-1 cells.

Enzymatic activity of coenzyme B(12) derivatives with altered axial nucleotides: probing the mechanochemical triggering hypothesis in ribonucleotide reductase

Theoretical studies (J. Inorg. Biochem. 2001, 83, 121) of the involvement of the bulky 5,6-dimethylbenzimidazole (Dmbz) ligand of coenzyme B(12) (5'-deoxyadenosylcobalamin, AdoCbl) in the mechanism of activation of the carbon-cobalt bond of the coenzyme for homolytic cleavage by AdoCbl-dependent enzymes (the "mechanochemical triggering" mechanisms) have shown that a purely steric, ground-state mechanism can supply only a few kilocalories per mole (of the observed 13-16 kcal mol(-1)) of activation, but that an electronic mechanism, operating to stabilize the transition state, can explain all of the observed catalytic effect. To address these mechanisms experimentally, analogues of AdoCbl in which the Dmbz ligand is replaced by benzimidazole (Ado(Bzim)Cbl) or by imidazole (Ado(Im)Cbl) have been prepared and characterized. Both of these analogues support turnover in the AdoCbl-dependent ribonucleoside triphosphate reductase (RTPR) from Lactobacillus leichmannii at 100% of the activity of AdoCbl itself, but the Ado(Im)Cbl analogue has a significantly higher K(m). 5'-Deoxyadenosylcobinamide, the analogue in which the axial nucleotide has been chemically removed, in contrast, is inactive in the spectrophotometric assay, which indicates that it has at most 1% of the activity of AdoCbl. Stopped-flow spectrophotometric measurements of the formation of cob(II)alamin at the enzyme active site show that RTPR binds Ado(Bzim)Cbl slightly more weakly than it does AdoCbl, but binds Ado(Im)Cbl 8-fold more weakly. While the equilibrium constant for cob(II)alamin formation is nearly the same for Ado(Bzim)Cbl and AdoCbl, it is 5-fold smaller for Ado(Im)Cbl. Finally, the forward rate constant for enzyme-induced Co-C bond homolysis was about the same for Ado(Bzim)Cbl and for AdoCbl but was 17-fold smaller for Ado(Im)Cbl. These results are consistent with a small contribution from ground-state mechanochemical triggering, but they do not in themselves rule out transition-state mechanical triggering.

Equilibrium and kinetic studies on the reactions of alkylcobalamins with cyanide

Ligand substitution equilibria of different alkylcobalamins (RCbl, R = Me, CH(2)Br, CH(2)CF(3), CHF(2), CF(3)) with cyanide have been studied. It was found that CN(-) first substitutes the 5,6-dimethylbenzimidazole (Bzm) moiety in the alpha-position, followed by substitution of the alkyl group in the beta-position trans to Bzm. The formation constants K(CN) for the 1:1 cyanide adducts (R(CN)Cbl) were found to be 0.38 +/- 0.03, 0.43 +/- 0.03, and 123 +/- 9 M(-1) for R = Me, CH(2)Br, and CF(3), respectively. In the case of R = CH(2)CF(3), the 1:1 adduct decomposes in the dark with CN(-) to give (CN)(2)Cbl. The unfavorable formation constants for R = Me and CH(2)Br indicate the requirement of very high cyanide concentrations to produce the 1:1 complex, which cause the kinetics of the displacement of Bzm to be too fast to follow kinetically. The kinetics of the displacement of Bzm by CN(-) could be followed for R = CH(2)CF(3) and CF(3) to form CF(3)CH(2)(CN)Cbl and CF(3)(CN)Cbl, respectively, in the rate-determining step. Both reactions show saturation kinetics at high cyanide concentration, and the limiting rate constants are characterized by the activation parameters: R = CH(2)CF(3), DeltaH = 71 +/- 1 kJ mol(-1), DeltaS = -25 +/- 4 J K(-1) mol(-1), and DeltaV = +8.9 +/- 1.0 cm(3) mol(-1); R = CF(3), DeltaH = 77 +/- 3 kJ mol(-1), DeltaS = +44 +/- 11 J K(-1) mol(-1), and DeltaV = +14.8 +/- 0.8 cm(3) mol(-1), respectively. These parameters are interpreted in terms of an I(d) and D mechanism for R = CH(2)CF(3) and CF(3), respectively. The results of the study enable the formulation of a general mechanism that can account for the substitution behavior of all investigated alkylcobalamins including coenzyme B(12).

Complete nucleotide sequence and characterization of pUA140, a cryptic plasmid from Streptococcus mutans

Approximately 5% of strains of Streptococcus mutans contain plasmid DNA. Strain UA140 harbors a 5.6-kb cryptic plasmid, pUA140, with an overall G+C content of 32.7%. Five open reading frames (ORF), encoding peptides of larger than 100 amino acid residues, were initially designated as ORF1 to ORF5. These five ORFs were located on the same strand of pUA140. ORF1 (258 amino acids) resembled a replication protein, Rep. Upstream of the putative Rep gene, a double-stranded origin for plasmid replication that showed strong similarity to those of a number of plasmids in the pT181 family was identified. Further upstream was a region constituting the single-stranded origin of replication. A single-stranded DNA intermediate was detected during plasmid replication. Taken together, these results suggest that pUA140 replicated by the rolling circle replication mechanism but exhibited several characteristics that differ from those of other members of the pT181 plasmid family.

The cell cycle-regulatory CDC25A phosphatase inhibits apoptosis signal-regulating kinase 1

CDC25A phosphatase promotes cell cycle progression by activating G(1) cyclin-dependent kinases and has been postulated to be an oncogene because of its ability to cooperate with RAS to transform rodent fibroblasts. In this study, we have identified apoptosis signal-regulating kinase 1 (ASK1) as a CDC25A-interacting protein by yeast two-hybrid screening. ASK1 activates the p38 mitogen-activated protein kinase (MAPK) and c-Jun NH(2)-terminal protein kinase-stress-activated protein kinase (JNK/SAPK) pathways upon various cellular stresses. Coimmunoprecipitation studies demonstrated that CDC25A physically associates with ASK1 in mammalian cells, and immunocytochemistry with confocal laser-scanning microscopy showed that these two proteins colocalize in the cytoplasm. The carboxyl terminus of CDC25A binds to a domain of ASK1 adjacent to its kinase domain and inhibits the kinase activity of ASK1, independent of and without effect on the phosphatase activity of CDC25A. This inhibitory action of CDC25A on ASK1 activity involves diminished homo-oligomerization of ASK1. Increased cellular expression of wild-type or phosphatase-inactive CDC25A from inducible transgenes suppresses oxidant-dependent activation of ASK1, p38, and JNK1 and reduces specific sensitivity to cell death triggered by oxidative stress, but not other apoptotic stimuli. Thus, increased expression of CDC25A, frequently observed in human cancers, could contribute to reduced cellular responsiveness to oxidative stress under mitogenic or oncogenic conditions, while it promotes cell cycle progression. These observations propose a mechanism of oncogenic transformation by the dual function of CDC25A on cell cycle progression and stress responses.

Structured population on two patches: modeling dispersal and delay

We derive from the age-structured model a system of delay differential equations to describe the interaction of spatial dispersal (over two patches) and time delay (arising from the maturation period). Our model analysis shows that varying the immature death rate can alter the behavior of the homogeneous equilibria, leading to transient oscillations around an intermediate equilibrium and complicated dynamics (in the form of the coexistence of possibly stable synchronized periodic oscillations and unstable phase-locked oscillations) near the largest equilibrium.

Novel control motif cluster in the IgH delta-gamma 3 interval exhibits B cell-specific enhancer function in early development

The majority of the human Ig heavy chain (IgH) constant (C) region locus has been cloned and mapped. An exception is the region between C delta and C gamma 3, which is unstable and may be a recombination hot spot. We isolated a pBAC clone (pHuIgH3'delta-gamma 3) that established a 52-kb distance between C delta and C gamma 3. Sequence analysis identified a high number of repeat elements, explaining the instability of the region, and an unusually large accumulation of transcription factor-binding motifs, for both lymphocyte-specific and ubiquitous transcription activators (IKAROS, E47, Oct-1, USF, Myc/Max), and for factors that may repress transcription (Delta EF1, Gfi-1, E4BP4, C/EBP beta). Functional analysis in reporter gene assays revealed the importance of the C delta-C gamma 3 interval in lymphocyte differentiation and identified independent regions capable of either enhancement or silencing of reporter gene expression and interaction with the IgH intron enhancer E mu. In transgenic mice, carrying a construct that links the beta-globin reporter to the novel delta-gamma 3 intron enhancer (E delta-gamma 3), transgene transcription is exclusively found in bone marrow B cells from the early stage when IgH rearrangement is initiated up to the successful completion of H and L locus recombination, resulting in Ab expression. These findings suggest that the C delta-C gamma 3 interval exerts regulatory control on Ig gene activation and expression during early lymphoid development.

[Human cytomegalovirus inhibits the proliferation of CFU-MK in vitro]

OBJECTIVE

To investigate the effect of human cytomegalovirus (HCMV) on the proliferation of colony forming unit-megakaryocyte (CFU-MK).

METHODS

Semi-solid CFU-MK culture system was used to observe the effect of HCMV AD169 strain on CFU-MK growth of 20 cord blood samples. HCMV DNA and immediate early antigen (IEA) mRNA in CFU-MK were detected by in situ-polymerase chain reaction (IS-PCR) and reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

HCMV AD169 suppressed the differentiation and proliferation of CFU-MK in vitro significantly. The suppression was in a dose-dependent fashion. HCMV DNA was successfully detected in colony cells from viral infection group, and did the expression of HCMV IEA mRNA.

CONCLUSION

HCMV AD169 can directly infect megakaryocyte progenitor and suppress their proliferation and differentiation.

Design, docking, and evaluation of multiple libraries against multiple targets

We present a general approach to the design, docking, and virtual screening of multiple combinatorial libraries against a family of proteins. The method consists of three main stages: docking the scaffold, selecting the best substituents at each site of diversity, and comparing the resultant molecules within and between the libraries. The core "divide-and-conquer" algorithm for side-chain selection, developed from an earlier version (Sun et al., J Comp Aided Mol Design 1998;12:597-604), provides a way to explore large lists of substituents with linear rather than combinatorial time dependence. We have applied our method to three combinatorial libraries and three serine proteases: trypsin, chymotrypsin, and elastase. We show that the scaffold docking procedure, in conjunction with a novel vector-based orientation filter, reproduces crystallographic binding modes. In addition, the free-energy-based scoring procedure (Zou et al., J Am Chem Soc 1999;121:8033-8043) is able to reproduce experimental binding data for P1 mutants of macromolecular protease inhibitors. Finally, we show that our method discriminates between a peptide library and virtual libraries built on benzodiazepine and tetrahydroisoquinolinone scaffolds. Implications of the docking results for library design are explored.

Helicobacter pylori seropositivity and subsite-specific gastric cancer risks in Linxian, China

BACKGROUND

Helicobacter pylori carriage (i.e., persistent exposure to the organism without gastric epithelial cell invasion) is an established risk factor for noncardia gastric cancer. However, its association with the risk of cancer of the gastric cardia is controversial. Consequently, we designed this prospective, nested case-control study to further explore the subsite-specific gastric cancer risks associated with H. pylori seropositivity (a surrogate marker for persistent exposure).

METHODS

A total of 99 patients with gastric cardia cancer, 82 patients with noncardia gastric cancer, and 192 cancer-free subjects were selected from among the participants (n = 29 584) of a nutrition intervention trial previously conducted in Linxian, China. H. pylori seropositivity was determined by assaying for the presence of H. pylori whole cell and CagA antibodies in baseline serum samples from all subjects. Seropositivity was defined as one or both serum assays being positive. Odds ratios (ORs) for subsite-specific gastric cancer were estimated by multivariate logistic regression analyses. All statistical comparisons were two-sided (alpha =.05).

RESULTS

H. pylori seropositivity rates for subjects with gastric cardia cancer, noncardia gastric cancer, and gastric cardia and noncardia cancers combined were 70% (P =.02), 72% (P: =.01), and 71% (P =.003) compared with 56% for cancer-free control subjects. OR estimates for H. pylori seropositivity were 1.87 (95% confidence interval [CI] = 1.10 to 3.17) for gastric cardia cancer, 2.29 (95% CI = 1.26 to 4.14) for noncardia gastric cancer, and 2.04 (95% CI = 1.31 to 3.18) for gastric cardia and noncardia cancers combined.

CONCLUSIONS

H. pylori seropositivity was associated with increased risks for both gastric cardia cancer and noncardia gastric cancer in this well-characterized cohort. Thus, H. pylori carriage may increase the risk of cancer throughout the stomach.

Adelta and C primary afferents convey dorsal root reflexes after intradermal injection of capsaicin in rats

Antidromic activity was recorded in anesthetized rats from single afferent fibers in the proximal ends of cut dorsal root filaments at the L(4-6) level and tested for responses to acute cutaneous inflammation produced by intradermal injection of capsaicin. This antidromic activity included low-frequency spontaneous firing and dorsal root reflex (DRR) discharges evoked by applying von Frey hairs to the skin of the foot. DRRs could be recorded from both small myelinated (Adelta) and unmyelinated (C) afferent fibers, as well as from large myelinated (Abeta) fibers. After capsaicin was injected intradermally into the plantar skin of the foot, a significant enhancement of DRR activity was seen in Adelta and C fibers but not in Abeta fibers, and this increase lasted for approximately 1 h. This study supports the hypothesis that centrally mediated antidromic activity in Adelta and C primary afferent fibers contributes to the development of neurogenic inflammation, presumably by release of inflammatory substances in the periphery.

Data assimilation and its applications

In data assimilation, one prepares the grid data as the best possible estimate of the true initial state of a considered system by merging various measurements irregularly distributed in space and time, with a prior knowledge of the state given by a numerical model. Because it may improve forecasting or modeling and increase physical understanding of considered systems, data assimilation now plays a very important role in studies of atmospheric and oceanic problems. Here, three examples are presented to illustrate the use of new types of observations and the ability of improving forecasting or modeling.

Enhanced phosphorylation of NMDA receptor 1 subunits in spinal cord dorsal horn and spinothalamic tract neurons after intradermal injection of capsaicin in rats

The functional enhancement of NMDA receptors after peripheral tissue injury is proposed to contribute to the sensitization of spinothalamic tract (STT) cells and hyperalgesia. Protein phosphorylation is a major mechanism for the regulation of NMDA receptor function. In this study, Western blots, immunofluorescence double labeling, and the retrograde tracing method were used to examine whether phosphorylation of NMDA receptor 1 (NR1) subunits increases in spinal cord tissue and spinal dorsal horn neurons, especially in STT cells, after injection of capsaicin (CAP) into the glabrous skin of one hindpaw of anesthetized rats. Western blots showed that phosphorylated NR1 protein in spinal cord tissue was increased 30 min after CAP injection. Immunofluorescence double-labeling staining showed no significant difference in the number of the NR1-like immunoreactive neurons in laminae I-VII in the lumbosacral segments (L(4)-S(1)) on the ipsilateral and the contralateral sides 30 min after CAP or vehicle injection. However, the numbers of phospho-NR1-like immunoreactive neurons were significantly increased on the ipsilateral side compared with the vehicle injection group. STT cells were labeled by bilateral microinjections of the retrograde tracer fluorogold into the lateral thalamus, including the ventral-posterior lateral nucleus. Immunofluorescence staining was performed at 30, 60, and 120 min after CAP injection or at 30 min after vehicle injection. There was a significant increase in the proportion of STT cells with phosphorylated NR1 subunits compared either with the contralateral side 30 and 60 min after CAP injection or either side of animals after intradermal injection of vehicle. These results provide direct evidence that NMDA receptors in STT cells are phosphorylated after CAP injection.

[The alterations in vasoactive intestinal polypeptide-immune reaction positive neurons of cerebral tissues in epileptic rats induced by penicillin]

To further explore the action of vasoactive intestinal polypeptide(VIP) in epileptogenesis, we made an immunocytochemical analysis and observed the alterations in VIP-energic neurons of the cerebral cortex, hippocampus and amygdaloid in rats. The animals were divided into three groups: the control, the epileptic group in which seizure was induced by injected Penicillin(PNC) intraperitoneally, and the nimodipline(NIM) group in which seizure was impressed by giving PNC after NIM, a dihydropyridine calcium entry blocker, was injected. The results showed that the number of neurons of epileptic group increased, compared with that of control group (P < 0.01), the neuronic number of the epileptic group was higher than that of the NIM group(P < 0.01), whereas there was no significant difference in neuronic number between the control group and the NIM group(P > 0.05). These suggest that VIP and Ca2+ participate in the process of epileptogenesis.

[The expression of trkC in spared dorsal root ganglion following unilateral dorsal root rhizotomy]

This study sought to explore the expression of trkC in spared dorsal root ganglion(DRG) following unilateral dorsal root rhizotomy. 15 cats were divided into three groups: the intact group, the 3-day and 10-day groups after operation (unilaterral L1-L5 DRG and L7-S2 DRG were sectioned, but L6 DRG was spared). The animals were sacrificed on the 3rd day and 10th day after operation, respectively. The L6 DRG from the three groups were taken and cut into frozen sections (20 microns). The sections were stained using specific antiserum for trkC by the immunohistochemical ABC method. The numbers of large sized neurons (> 57 microns) and small sized neurons (< 42 microns) for trkC-IR were counted respectively. The results showed that the number of positive large sized neurons for trkC of the 10-day group after operation decreased significantly than that of the intact group and the 3-day group after operation, while the number of positive small sized neurons for trkC of the 10-day group increased apparently than that of the intact group and the 3-day group after operation (P < 0.05). This experiment demonstrated that unilateral partial dorsal root rhizotomy could change the expression of trkC might in large neurons and small sized neurons, and the results suggested that trkC might involve in the spinal cord plasticity following partial dorsal root rhizotomy.

[Preliminary isolation and identification of neurotrophic factors sensory neurons in spinal dorsal horn of embryonic chicken]

Our previous studies have demonstrated that the extract from dorsal horn of embryonic chicken can promote apparently the neurite growth of spinal ganglion during development. In this study, we investigated progressively the neurotrophic factors for primary sensory neurons in spinal dorsal horn. The tissues of spinal dorsal horn from five hundred Hamburger Stage-40 embryonic chickens were taken. After homogenization and centrifugation, the supernatant was subjected to SDS-polyacrylamide gel electrophoresis (SDS-PAGE) for analyzing the protein in dorsal horn. The simple protein band fishing by cell (SPBFC) technique was employed in finding the protein bands with neurons attached, and then such protein bands, were taken and transferred to nitric cellulose paper for Western hybridization analysis by antibody for NGF, BDNF, NT-3 and GDNF respectively. The results of SPBFC showed that some neurons were attached to gel within the scope of mobility relative front (Rf) 0.10-0.19, 0.30-0.35, 0.50-0.55, 0.60-0.67 and 0.90-0.94 respectively, indicating there were some neurotrophic factors for maintaining neuron survival in the above Rf scope. Moreover, the result of Western hybridization showed that the positive hybridization bands in each scope were that of NGF, BDNF, GDNF; NGF, BDNF, NT-3; NGF, BDNF, NT-3; NGF, NT-3 and BDNF, NT-3 respectively; indicating that the neurotrophic effect of spinal dorsal horn tissue on primary sensory neurons involves NGF, BDNF, NT-3 and GDNF. These also suggest that the neuronal survival effect in each Rf scope involves at least two or more neurotrophic factors.