Prenatal exposure to cocaine disrupts D1A dopamine receptor function via selective inhibition of protein phosphatase 1 pathway in rabbit frontal cortex

Previous work has demonstrated that in utero cocaine exposure induces an uncoupling of brain D(1A) dopamine receptors (D(1A)DARs) from G(s)-protein. The present work is an attempt to define the mechanism underlying the uncoupling. We detected a significant elevation of phosphoserine in frontal cortical D(1A)DARs of rabbits that were exposed prenatally to cocaine compared with saline controls. This increase in phosphorylation is observed at gestational day 22 and persists to postnatal day 20. The hyperphosphorylation of the D(1A)DAR is accompanied by a 45% inhibition in frontal cortex (FCX) protein phsphatase-1 (PP1) activity that appears to be mediated via DARPP-32 (dopamine and cAMP-regulated phosphoprotein) as indicated by elevated FCX phospho-DARPP-32 (Thr(34)). Furthermore, we demonstrated in both FCX and in PC2 cells that express D(1A)DARs that PP1 is physically associated with D(1A)DARs. We also observed a dramatic decrease in D(1A)DAR-associated PP1 activity in FCX of prenatal cocaine-exposed rabbits, indicating that the reduction in PP1 activity may be responsible for the hyperphosphorylation of the receptor. Furthermore, pretreatment of cortical membranes obtained from cocaine-exposed animals with exogenous PP1 dephosphorylated the phosphorylated D(1A)DAR and significantly reversed the impaired receptor-G(alphas) coupling. This work indicates (1) that D(1A)DAR dephosphorylation via PP1 is essential for receptor resensitization or reactivation and (2) an alteration in the DARPP-32/PP1 cascade appears to be a primary event responsible for D(1A)DAR dysfunction in in utero cocaine-exposed rabbit progeny. The present finding of an altered DARPP-32/PP1 cascade in association with a dysfunction in D(1A)DAR signal transmission in the prenatal cocaine-exposed rabbit brain may implicate novel strategies for the prevention and treatment for in utero cocaine-induced developmental and behavioral abnormalities.

[Coding region cDNA sequence cloning of rat neuroglobin gene, its polymorphism feature and tissue expression profile analysis]

The coding region cDNA sequence of rat neuroglobin (NGB) was obtained by RT-PCR technique using a degeneracy PCR primer pair based on previously reported cDNA sequence of human and mouse NGB gene. Result demonstrated that the coding region cDNA sequence of rat NGB gene is 456 bp in length, which could encode a protein of 151 amino acids. The rat NGB gene is highly homology with mouse (96%) and human (88%) NGB gene. However, several polymorphism sites were also detected in the rat NGB coding region: 113 t/c [L38P], 133 a/g [N45D], 388 a/g[R130G], 417 t/c. The cDNA sequence of rat NGB gene has been registered in GenBank under the accession number AF333245. Moreover, highly expression level of rat NGB in brain, liver, kidney, heart and skeletal muscle was detected by using multiple tissue RT-PCR technique, indicating the functional importance of this novel gene.

Erianin induces apoptosis in human leukemia HL-60 cells

AIM

To investigate the effect of erianin on human HL-60 cell line and explore its mechanism of apoptosis in vitro.

METHODS

Inhibition of proliferation was measured with colorimetric MTT assay. The morphologic changes were observed by fluorescence and electron microscopes. DNA fragmentation was visualized by agarose gel electrophoresis, and the DNA degradation was determined by flow cytometry. Immunohistochemical analysis was used to identify the expression of bcl-2 and bax genes.

RESULTS

The growth of human HL-60 cells was significantly inhibited by erianin 20-81.9 nmol/L during 72 h treatment (P < 0.01). The IC50 value was 38 nmol/L after a 24-h exposure to erianin, while that of vincristine, the positive control, was 101 nmol/L. The typical morphologic changes were observed and the nuclear DNA fragmentation exhibited "ladder" pattern. The cell cycle of HL-60 cells was arrested in G2/M phase, and expression of bcl-2 gene was decreased while that of bax was increased.

CONCLUSION

Erianin showed potent inhibitory activity on the proliferation of HL-60 cells. The inhibition might be relative to the apoptosis induced by erianin and the altered expression of bcl-2 and bax genes in HL-60 cells.

Galpha(i2) enhances insulin signaling via suppression of protein-tyrosine phosphatase 1B

Suppression of the expression of the heterotrimeric G-protein Galpha(i2) in vivo has been shown to provoke insulin resistance, whereas enhanced insulin signaling is observed when Galpha(i2) is overexpressed in vivo. The basis for Galpha(i2) regulation of insulin signaling was explored in transgenic mice with targeted expression of the GTPase-deficient, constitutively active Q205L Galpha(i2) in fat and skeletal muscle. Phosphorylation of insulin receptor and IRS-1 in response to insulin challenge in vivo was markedly amplified in fat and skeletal muscle expressing Q205L Galpha(i2). The expression and activity of the protein-tyrosine phosphatase 1B (PTP1B), but not protein-tyrosine phosphatases SHP-1, SHP-2, and LAR, were constitutively decreased in tissues expressing the Q205L Galpha(i2), providing a direct linkage between insulin signaling and Galpha(i2). The loss of PTP1B expression may explain, in part, the loss of PTP1B activity in the iQ205L transgenic mice. Activation of Galpha(i2) in mouse adipocytes with lysophosphatidic acid was shown to decrease PTP1B activity, whereas pertussis toxin inactivates Galpha(i2), blocks lysophosphatidic acid-stimulated inhibition of PTP1B activity, and blocks tonic suppression of PTP1B activity by Galpha(i2). Elevation of intracellular cAMP in fat cells is shown to increase PTP1B activity, whereas either depression of cAMP levels or direct activation of Galpha(i2) suppresses PTP1B. These data provide the first molecular basis for the interplay between Galpha(i2) and insulin signaling, i.e. activation of Galpha(i2) can suppress both the expression and activity of PTP1B in insulin-sensitive tissues.

Lithium suppresses signaling and induces rapid sequestration of beta2-adrenergic receptors

Lithium is a monovalent cation used therapeutically to treat a range of affective disorders (1), although the cellular mechanisms of lithium regulation that might contribute to its therapeutic effects at the level of neurotransmitter receptors are not known. Herein we report the ability of lithium to stimulate the internalization of beta2-adrenergic receptors. Lithium treatment of A431 human epidermoid carcinoma cells resulted in a rapid, prominent desensitization and internalization of beta2-adrenergic receptors. The ability of these receptors to generate a cyclic AMP response was strongly inhibited by lithium, at concentrations therapeutic in humans. Receptors for the serotonin (5HT1c) and for opiates (mu-opioid), in sharp contrast, resisted the effects of lithium on internalization. These data provide the first receptor-based mechanism to be described for lithium that could explain, in part, the therapeutic effects of lithium on affective disorders.

Identification and characterization of a novel human hepatocellular carcinoma-associated gene

To investigate liver cancer-associated genes and to explore the molecular basis of liver cancer genesis, we have cloned a novel hepatocellular carcinoma (HCC)-related gene with a transcript of 2520 base pairs in length named HCCA2 by mRNA differential display polymerase chain reaction (DDPCR) and screening a placenta cDNA library. No significant homologous protein with known genes was found. Western blot analysis showed that HCCA2 could be expressed in transfected 293 cells. Northern hybridization analysis showed that HCCA2 mRNA was expressed in 79% (34/43) patients with HCC, most of whom had significantly high expression in HCC tissues, while not expressed in corresponding noncancerous liver tissues. The clinical pathological data showed that the HCCA2 was significantly associated with the invasion of tumour capsule (P = 0.0007) and the expression of ki-67 protein (P = 0.0022). Immunohistochemical staining confirmed that the HCCA2 protein was localized in cytoplasm of liver cancer tissues. According to amino acid analysis of the protein and its localization, it may play a role in a cascade of intracellular signal transduction because the protein was characterized with two Src homology 3 (SH3) binding-domains and several functional motifs of phosphorylation.

Naloxone increases vascular responsiveness in chronic morphine treated rats and facilitates intracellular signaling in cultured vascular cells

AIM

To probe the changes of vascular responsiveness and intracellular signaling during opiate withdrawal syndrome.

METHODS

Morphine withdrawal syndrome in rats was precipitated by iv naloxone following daily injection of increasing dose of morphine for 2 weeks, the changes in mean arterial blood pressure (MBP) caused by acetylcholine (ACh) were recorded. Isolated mesenteric vascular beds were perfused with Kreb's solution containing different concentration of drugs. The cytoplasmic Ca2+ ([Ca2+]i) in Fura 2-loaded cultured bovine aortic endothelial cells (aec) and smooth muscle cells (smc) were assayed. The positive immunoreaction to the phosphorylated cyclic AMP responsive element-binding protein (phospho-CREB) in cultured smc was calculated.

RESULTS

Naloxone 2 mg/kg iv following chronic morphine treatment precipitated severe opiate withdrawal signs in company with blunted hypotensive effect of Ach that was the same as chronic morphine treated rats before withdrawal. In the mesenteric vascular beds from chronic morphine treated rats, the EC50 of pressor effect of norepinephrine (NE) was decreased from (2.06 +/- 0.38) to (1.14 +/- 0.21) micromol/L (n = 8, P < 0.01) after the perfusion solution containing morphine 20 micromol/L was replaced by Kreb's containing naloxone 25 micromol/L. Furthermore, NE-induced perfusion pressure increases were completely prevented by Kreb's contained morphine 40 micromol/L. Morphine acutely applied to control smc produced some variable and naloxone-reversible [Ca2+]i changes, but naloxone did not. However, naloxone increased [Ca2+]i in two thirds of smc preincubated with morphine 0.1 or 0.5 mmol/L for 48 h from (97 +/- 20) to (167 +/- 29) nmol/L (n = 9, P < 0.01) and from (106 +/- 19) to (225 +/- 48) nmol/L (n = 10, P < 0.01), respectively, and it also increased the ratio of positive immunoreaction to phospho-CREB from (7.7 +/- 3.2) % to (19.6 +/- 4.7) % (n = 6, P < 0.01) in smc preincubated with morphine 0.5 mmol/L. In addition, naloxone decreased [Ca2+]i from (146 +/- 34) to (78 +/- 24) nmol/L in one third morphine-preincubated aec (n = 10, P < 0.01).

CONCLUSION

That naloxone enhances vascular responsiveness to NE in chronic morphine treatment rats may be relevant to [Ca2+]i transient facilitation in company with cAMP-dependent phosphorylation enhancement.

Lithium treatment inhibits protein kinase C translocation in rat brain cortex

RATIONALE

Lithium, an effective psychotropic agent, affects membrane phospholipid metabolism, interferes with phosphoinositide signal transduction, and antagonizes the biological activity of calcium, all major factors of protein kinase C (PKC) activation. Consequently, lithium may interfere with cellular functions requiring PKC. Supporting this hypothesis, lithium was found to inhibit increased neurotransmitter release upon PKC activation and to prevent phorbol ester-mediated PKC translocation.

OBJECTIVES

The present study was undertaken to determine whether the frontal cortex of rats treated with lithium exhibits altered PKC activity and translocation in response to phorbol ester, K+, or serotonin (5-HT) receptor stimulation and to determine whether specific PKC isozymes are disproportionately affected.

METHODS

Rats were fed either a normal diet or one enriched with LiCl. In cerebrocortical slices or synaptosomes, cytosolic and membranous PKC activity and translocation in response to stimuli were determined after partial purification with anion exchange chromatography.

RESULTS

In brain slices, lithium treatment inhibited phorbol 12-myristate, 13-acetate (PMA)-, 5-HT-, or K+-induced PKC translocation from cytosol to membrane without affecting basal membrane or cytosolic PKC activity. In synaptosomes, lithium also attenuated PMA- or K+-evoked translocation of PKC. Immunoblotting with isozyme-specific PKC antibodies revealed that chronic lithium treatment reduced basal cytosolic alphaPKC and deltaPKC but increased membrane-associated zetaPKC immunoreactivities. Stimulation with PMA, 5-HT or K+ elicited translocation of alpha, beta and gammaPKC isozymes and PMA induced translocation of delta and epsilonPKC isozymes. Stimulus-mediated translocation of PKC isozymes was attenuated in cortical tissue obtained from animals that received lithium for 6 weeks. In synaptosomes, PMA- or K+-induced PKC translocation was attenuated by in vitro lithium or chronic lithium treatment. Neither rubidium nor cesium affected PKC activities or PMA-induced translocation. Suppression of PMA-elicited translocation by lithium was partially antagonized by Ca2+.

CONCLUSIONS

Lithium treatment reduces PKC translocation induced by either stimulation of a cell surface receptor or by direct enzyme stimulation with phorbol ester. This effect leads to reduced PKC-mediated phosphorylation of cellular proteins and may be responsible for the pharmacotherapeutic action of lithium.

Epidemiologic and clinical survey of Behcet's disease in Korea: the first multicenter study

The prevalence of Behcet's disease is the highest in the East Asian and the Mediterranean countries. Behcet's disease is also distributed in the Asian countries, but the nationwide survey has not been performed in Korea yet. The Korean Study Group for Behcet's Disease, founded in 1999, conducted a multicenter, retrospective survey on epidemiologic and clinical features of the patients with Behcet's disease from 20 hospitals around the nation from 1997 to 1999. Of 3,497 patients, 1,527 were classified into complete or incomplete type of Behcet's disease according to the revised Shimizu's classification. The sex ratio was 1:1.75 with the female predominance. Geographical distribution showed the highest frequency in Seoul (38.5%). Clinically, 98.8% had oral ulcers, 83.2% had genital ulcers, 84.3% had skin lesions and 50.9% had ocular lesions. As for the minor clinical manifestations, articular symptoms were the most frequent. The pathergy test showed positive in 15.4% of patients and revealed a higher positive rate in males (20.2%) than in females (12.7%). In conclusion, we performed the first multicenter study on Behcet's disease in Korea and revealed the female predominance, higher frequency of ocular lesions, and lower positivity of pathergy test in the patients.

beta-Catenin expression in the transitional cell zone of pilomatricoma

BACKGROUND

beta-Catenin, a participant in the Wnt pathway, has been shown to play an important role in the morphogenesis of hair follicles and the formation of hair follicle-related tumours, including pilomatricomas. It has been observed that at least 75% of human pilomatricomas possess activating mutations in beta-catenin. These findings suggested that beta-catenin plays an important role in the tumorigenesis of pilomatricomas. However, the pattern of beta-catenin expression in pilomatricoma tissues is still unclear. Objectives To examine the expression of beta-catenin in human pilomatricomas by immunohistochemical staining.

METHODS

Twenty-six formalin-fixed and paraffin-embedded samples of pilomatricoma tissue were studied.

RESULTS

Most transitional cells of pilomatricoma expressed beta-catenin strongly, but the basophilic cells and shadow cells did not. beta-Catenin showed a prominent membranous immunoreactivity and a small amount of condensed cytoplasmic staining, but there was definitely no evidence of nuclear positivity.

CONCLUSIONS

These findings imply that beta-catenin is primarily involved in cell-cell adhesion rather than cellular proliferation during pilomatricoma pathogenesis, and suggest that if beta-catenin is involved in pilomatricoma tumorigenesis and tumour growth, it plays an indirect role.

Molecular phylogeny of gobioid fishes (Perciformes: Gobioidei) based on mitochondrial 12S rRNA sequences

The molecular phylogeny of the gobioid fishes, comprising 33 genera and 43 valid species, was examined by use of complete mitochondrial 12S rRNA and tRNA(VAL)genes. Both parsimony and neighbor-joining analyses revealed comparable results and are generally congruent with those of morphological studies. The Odontobutis, which was always placed at the base of the phylogenetic trees, can be treated as a sister group of all other nonrhyacichthyid gobioids. Within eleotrid fishes, the monophyly of the Eleotrinae is strongly supported by molecular data. The Butinae is closer to fishes with five branchiostegal rays and should be treated as a sister group of the latter. The group with five branchiostegal rays, except for sicydiines, can be divided into two groups according to their epural counts. Fish with one epural, the Gobiinae of Pezold plus Microdesmidae, form a monophyletic group which is sister to those with two epurals, the Oxudercinae and Gobionellinae of Pezold. However, Sicydiinae, which have one epural, are closer to the Oxudercinae and Gobionellinae rather than to the Gobiinae. Since progressive reduction in epural number has been observed along this lineage, the sicydiines should be treated as a derived group within the groups with two epurals.

Stimulated D(1) dopamine receptors couple to multiple Galpha proteins in different brain regions

Previous studies have revealed that activation of rat striatal D(1) dopamine receptors stimulates both adenylyl cyclase and phospholipase C via G(s) and G(q), respectively. The differential distribution of these systems in brain supports the existence of distinct receptor systems. The present communication extends the study by examining other brain regions: hippocampus, amygdala, and frontal cortex. In membrane preparations of these brain regions, selective stimulation of D(1) dopamine receptors increases the hydrolysis of phosphatidylinositol/phosphatidylinositol 4,5-biphosphate. In these brain regions, D(1) dopamine receptors couple differentially to multiple Galpha protein subunits. Antisera against Galpha(q) blocks dopamine-stimulated PIP(2) hydrolysis in hippocampal and in striatal membranes. The binding of [(35)S]GTPgammaS or [alpha-(32)P]GTP to Galpha(i) was enhanced in all brain regions. Dopamine also increased the binding of [(35)S]GTPgammaS or [alpha-(32)P]GTP to Galpha(q) in these brain regions: hippocampus = amygdala > frontal cortex. However, dopamine-stimulated binding of [(35)S]GTPgammaS to Galphas only in the frontal cortex and striatum. This differential coupling profile in the brain regions was not related to a differential regional distribution of the Galpha proteins. Dopamine induced increases in GTPgammaS binding to Galpha(s) and Galpha(q) was blocked by the D(1) antagonist SCH23390 but not by D(2) receptor antagonist l-sulpiride, suggesting that D(1) dopamine receptors couple to both Galpha(s) and Galpha(q) proteins. Co-immunoprecipitation of Galpha proteins with receptor-binding sites indicate that in the frontal cortex, D(1) dopamine-binding sites are associated with both Galpha(s) and Galpha(q) and, in hippocampus or amygdala, D(1) dopamine receptors couple solely to Galpha(q). The results indicate that in addition to the D(1)/G(s)/adenylyl cyclase system, brain D(1)-like dopamine receptor sites activate phospholipase C through Galpha(q) protein.

Feasibility study of repeated harvesting of menthol from biologically viable Mentha x piperata using ultrasonic extraction

To potentially replace the conventional destructive extraction process, we have shown the feasibility of devising a novel technique that uses ultrasound to nonlethally and repeatedly extract menthol from biologically viable peppermint plants (Mentha x piperita). Our results show that plants ultrasonicated for 1 h at 22 degrees C in a standard 40 kHz ultrasonic bath could release approximately 17.8 microg of menthol per gram of leaf tissue (2% of total product). The amount of menthol release increases with the time of treatment and is greatly affected by the temperature of the ultrasonic bath water. An increase from 2% to 12% of total product was observed when the temperature was increased from 22 degrees C to 39 degrees C. When the temperature effects were isolated, the mechanism of the product release was found to be that of cavitation. The treated plants remained viable and were ready for the subsequent ultrasound extraction after approximately 4 days of recuperation. However, the amount of product released is reduced in subsequent extractions. Scanning electron micrographs indicate that there are two mechanisms involved in extraction: (1) the diffusion of product through the cuticle of peppermint glandular trichomes and (2) the exudation of the product from broken and damaged trichomes. This study has shown the possibility of using an on-line ultrasonic, nondestructive extraction method to continuously release intracellular plant metabolites from the plants while maintaining the plant's viability.

Selected contribution: effects of ischemia-reperfusion on vascular contractility and alpha(1)-adrenergic-receptor signaling in the rat tail artery

To determine the effects of ischemia-reperfusion (I/R) on alpha(1)-adrenergic-receptor (alpha(1)-AR) functions, alpha(1)-AR-mediated contraction, inositol phosphate (IP) accumulation, and alpha(1)-AR-G protein coupling were examined in the tail arteries of anesthetized rats after 60 min of ischemia and 60 min of reperfusion. The contractile response to norepinephrine (NE) was significantly increased after I/R, whereas the contractile response to KCl remained unchanged. This was accompanied by a 69% increase in NE-stimulated IP accumulation. Furthermore, receptor-stimulated coupling of alpha(1a)-AR to G alpha(q/11) proteins was increased, whereas the coupling of alpha(1b)-AR or alpha(1d)-AR to their G proteins was not altered by I/R. These changes in vascular alpha(1)-AR function occurred without concurrent alteration in expression levels of membrane alpha(1)-AR subtypes or in the associated G proteins. These data demonstrate that I/R increases alpha(1a)-AR-G(q/11) protein coupling and alpha(1)-AR-stimulated IP accumulation in the tail artery. The alterations in alpha(1)-AR signaling are associated with and may underlie the enhanced contractile response of the tail artery to adrenergic stimulation after I/R.

Loss of heterozygosity and its correlation with clinical outcome and Epstein-Barr virus infection in nasopharyngeal carcinoma

Sixty-one human nasopharyngeal carcinomas (NPC) were examined by allelotype analysis for the purposes of detecting potential association between loss of heterozygosity (LOH), clinicopathological parameters and Epstein-Barr virus (EBV) infection. LOH was performed using 257 polymorphic markers on 22 chromosomes. High frequency LOH (> or = 60%) was observed on 12 chromosome arms including 1p, 2p, 2q, 3p, 3q, 5q, 9p. 9q, 11q, 13q, 14q and 17q, with the highest LOH frequency of 91% on 3p. Seventy-three loci presented LOH frequency > or = 30%; most of these loci clustered on 1p36 p34, 2p25-p24, 3p14-p21, 3p24-p26, 5q11-q14, 5q31-q33, 9p21-p23, 9q33-q34, 11q23-q25, 13q12 q14, 13q31-q33, 14q13-q11, 14q32 and 19q13. On 1p36-p34, 2p25-p24, 5q13-q11, 5q31-q33 and 19q13 are reported for the first time. LOH was correlated with specific clinicopathological parameters including tumor T-stage, N-stage, TNM-stage, tumor differentiation and serum antibody titers of IgA against virus capsid antigens (VCA) and early antigen (EA) of EBV in NPC (LOH frequency > or = 30%). Significantly high LOH frequency was observed on 9p21 (56%) and 19q13 (50%) in NPC with stage T3+T4, while significantly higher LOH frequency was observed on 12p11 (65%) in NPC with stage T1 + T2. Significantly higher LOHfrequency on 19q13 was also observed in NPC with advanced TNM-stage (III+IV). High fractional allelic loss (FAL) value and high antibody titers of EBV IgA/VCA and/or IgA/EA were significantly correlated with T3 + T4-stage, distant lymph node metastasis and advanced TNM-stage of NPC. We also found that NPC patients with high titers of IgA/VCA and IgA/EA showed high LOH frequency on 16q (48%) and 19q13 (48%). These results suggest that LOH on 9p21, l6q and 19q13 may be responsible for the aggressiveness and progression of NPC; there may be an interaction between allelic loss and EBV infection in the etiology of NPC. High frequency of LOH on 4q21 and 14q11-q12 were alsofound to be correlated with WHO type III NPC histopathology, suggesting that LOH on these regions may cause poor NPC differentiation. Our data also may be useful for the development of a NPC molecular staging system, a system which may augment the use of clinical pathological features in the diagnosis and prognosis of this disease.

Is periodontitis genetic? The answer may be Yes!

Specific bacteria cause periodontitis by activating immuno-inflammatory responses in the tissues. There are certain risk factors that significantly affect the disease process by altering the immuno-inflammatory response and increasing the likelihood of severe periodontitis. These risk factors are smoking, diabetes, IL-1 genotype, and perhaps others. Today about 20 percent of the population smokes at a level that should make a difference relative to periodontitis. About 30 to 33 percent of the Caucasian population is IL-1 genotype positive. There are compelling reasons to look at these risk factors in your practice to help formulate a complete treatment plan for your patients.

Genome-wide analyses on loss of heterozygosity in hepatocellular carcinoma in Southern China

BACKGROUND/AIMS

To conduct a genome-wide analysis of loss of heterozygosity (LOH) and its clinical significance in hepatocellular carcinoma (HCC) in Southern China where high incidence of HCC was documented.

METHODS

LOH of 382 microsatellite loci on all autosomes were detected with polymerase chain reaction-based microsatellite polymorphism analyses in 104 HCC tumor tissues.

RESULTS

High frequency of LOH (>55.7%) was observed on chromosome 1p, 1q, 2q, 3p, 4q, 6q, 8p, 9p, 13q, 16q, and 17p. LOH rates on loci D4S2964 (4q21.21), D8S277 (8p23.1-pter) and D17S938 (17p13.1-p13.3) were significantly higher in cases with positive HBsAg than in those with negative HBsAg. Similarly, LOH on loci D1S214 (lp36.3), D1S2797 (1p34) and D3S3681 (3p11.2-p14.2) were more frequently detected in tumors with intrahepatic metastasis than in those without.

CONCLUSIONS

Status of LOH in HCC in Southern China is similar to that reported previously in other countries and areas. However, we firstly identified high-frequency LOH on chromosome 3p in HCC. Furthermore, HBV infection, as well as tumor intrahepatic metastasis, may be correlated with allelic losses on certain chromosome regions.

Cbl promotes ubiquitination of the T cell receptor zeta through an adaptor function of Zap-70

Triggering of the T cell antigen receptor (TCR).CD3 complex induces its ubiquitination. However, the molecular events that lead to ubiquitin conjugation to these cell surface molecules have not been defined. Here we report that Cbl, a RING-type E3 ubiquitin-protein ligase, promotes ubiquitination of TCR zeta chain, which requires its functional variant Src homology 2 domain and an intact RING finger. The tyrosine kinase Zap-70, which binds to both TCR zeta and Cbl, plays an adaptor role in these events. Mutations in TCR zeta, Zap-70, or Cbl that disrupt the interaction between TCR zeta and Zap-70 or between Zap-70 and Cbl reduce ubiquitination of TCR zeta. Our results suggest a novel mechanism by which Cbl negatively regulates T cell development and activation by inducing ubiquitination of the TCR.CD3 components.

[The primary role of central region of HC-pro of potato Y potyvirus in synergism of plant viruses]

Five deleted mutants of HC-Pro gene of Chinese isolate of potato Y potyvirus (PVY-C) were obtained by PCR mutation, and their plant expression vectors were constructed. They were transformed into tobacco K326 (Nicotina tabacum cv. K326) mediated by Agrobacterium. PCR and Southern blot analysis revealed that PVY-C HC-Pro gene and its deleted mutants were integrated into tobacco genome, and Western blot analysis showed that they were all expressed in transgenic tobacco plants. Furthermore, infection test demonstrated that the central region of PVY-C HC-Pro can mediate synergism of PVY-C/cucumber mosaic cucumovirus (CMV) and PVY-C/potato X potexvirus (PVX), identifying that it is functional domain in synergism.

Functional studies of bradykinin receptors in Chinese hamster ovary cells stably expressing the human B2 bradykinin receptor

Bradykinin B1 and B2 receptors, members of the G-protein coupled receptor superfamily, are involved in inflammation and pain. Chinese hamster ovary (CHO) cells stably expressing the human B2 bradykinin receptor (CHO-B2) were used to characterize the signal transduction pathways associated with this receptor and its regulation. The selective B2 antagonist [3H]NPC17731 but not the selective B1 antagonist [3,4-prolyl-3,4-(3)H(N)]-[des-Arg10,Leu9]kallidin ([3H]DALKD) bound to CHO-B2 cell membranes with a Kd of 0.77 nM and a Bmax of 1087 fmol/mg protein. [3H]NPC17731 binding was inhibited by bradykinin ligands in the order: NPC17731 > bradykinin > kallidin >> DALKD > [des-Arg10] kallidin (DAKD), consistent with the pharmacological profile of B2 bradykinin receptors. The B2 agonist bradykinin and the B1/B2 agonist kallidin, but not the B1 agonist DAKD, increased [35S]GTP gamma S binding to the CHO-B2 cell membranes. The B2 bradykinin receptors were co-immunoprecipitated with G alpha q/11. In response to bradykinin stimulation, coupling of the B2 receptors to G alpha q/11 was increased by 10-fold. Bradykinin and kallidin, but not DAKD, induced intracellular calcium release in CHO-B2 cells, which was blocked by NPC17731 but not by DALKD. These results demonstrate that B2 bradykinin receptors directly coupled to G alpha q/11 to regulate intracellular calcium release. CHO-B2 cell is a useful system that can be applied to study the effect of potential agents that may influence the B2 receptor function.

Permeabilization of metabolites from biologically viable soybeans (Glycine max)

Chemical permeabilization has been widely studied for the release useful metabolites from many types of plant cells and tissues. In this study, the effect of 0-30% (v/v) of aqueous methanol solutions were used to permeabilize soybeans for the release of two isoflavonoids: daidzein and genistein. The release of these metabolites increases with increasing methanol concentrations. The amounts of daidzein and genistein released can increase up to 40- and 86-fold, respectively, when incubated in a 30% (v/v) methanol solution for 24 h compared with those incubated with water only. The effect of methanol on the release rates is primarily due to an increase in solubility of the stored daidzein and genistein (14- to 18-fold) inside the seeds, thus maximizing the concentration gradients for metabolite release. However, the viability of the seeds dropped with increase in methanol concentrations and the incubation time. The viability of soybeans (indicated by their ability to germinate) after permeabilization treatment with 0-20% (v/v) methanol solutions was maintained above 80% throughout the 24 h, whereas no seeds were found to be viable when 30% (v/v) methanol solution was used. The permeability coefficients (P) of daidzein and genistein were found to increase as the methanol concentration used was increased. These P values were estimated to range from 1.1 x 10(-)(9) to 1.9 x 10(-)(8) m/s and 1.0 x 10(-)(9) to 1.7 x 10(-)(8) m/s, respectively. The increase in P can be attributed primarily to an increase in the partition coefficient of the metabolites in the soybean seedcoats. An empirical correlation is proposed in which the log P values are described as a function of the metabolite molecular weights and the partition coefficients of the metabolites between octanol and water, K(oct/water), which was modified to include the effect of methanol present. Knowledge obtained from this study will help provide useful selection criteria for chemical permeabilization of plant tissues, such as seeds, with minimal loss in their viability.

Surgical treatment for concomitant fractures of the femoral neck and diaphysis: a treatment protocol

Concomitant ipsilateral femoral shaft and neck fractures are difficult to treat. The standard protocol in our hospital is plates for diaphyseal fractures and lag screws or dynamic hip screws (DHS) fixations for the femoral neck fractures. We treated 21 patients with these complex fractures between 1988 and 1998 with this protocol. All patients were injured from high-energy trauma. There were 15 males and 6 females with an average age of 44 years. The average follow-up period is 50 months. All except one patient united well. During the follow-up period, neither non-union of the femoral neck fracture nor osteonecrosis of the femoral head was noted. There was also no malunion. There were twenty good results and one poor functional result. We conclude that plate on the shaft and sliding hip screws or separate screws in the hip are a reliable method for concomitant ipsilateral femoral neck and shaft fractures.

Costimulation of resting B lymphocytes alters the IL-4-activated IRS2 signaling pathway in a STAT6 independent manner: implications for cell survival and proliferation

IL-4 is an important B cell survival and growth factor. IL-4 induced the tyrosine phosphorylation of IRS2 in resting B lymphocytes and in LPS- or CD40L-activated blasts. Phosphorylated IRS2 coprecipitated with the p85 subunit of PI 3' kinase in both resting and activated cells. By contrast, association of phosphorylated IRS2 with GRB2 was not detected in resting B cells after IL-4 treatment although both proteins were expressed. However, IL-4 induced association of IRS2 with GRB2 in B cell blasts. The pattern of IL-4-induced recruitment of p85 and GRB2 to IRS2 observed in B cells derived from STAT6 null mice was identical to that observed for normal mice. While IL-4 alone does not induce activation of MEK, a MEK1 inhibitor suppressed the IL-4-induced proliferative response of LPS-activated B cell blasts. These results demonstrate that costimulation of splenic B cells alters IL-4-induced signal transduction independent of STAT6 leading to proliferation. Furthermore, proliferation induced by IL-4 in LPS-activated blasts is dependent upon the MAP kinase pathway.

The role of nitric oxide on cigarette smoke-induced programmed cell death in the gastric mucosa

BACKGROUND

This study was designed to investigate the effect of cigarette smoking on apoptosis in the gastric mucosa and the role of nitric oxide (NO) in the gas phase and extracts in the tar phase in this pathological process.

METHODS

Male Sprague-Dawley rats and human gastric epithelial cell line AGS were used in the study.

RESULTS

Cigarette smoking significantly increased apoptotic bodies in the rat gastric mucosa. However, neither filtered cigarette smoke, in which most of the substances in the tar phase were removed, nor oral administration of the two cigarette smoke extracts produced any effect on apoptosis. Interestingly, in this experiment pretreatment with a NO donor, the chloroform extract (CE) could significantly increase apoptosis. In in vitro study, only the CE induced DNA fragmentation, which could be elevated further by preincubation with a NO donor. The same extract also elevated inducible nitric oxide synthase (iNOS) activity. Inhibition of iNOS by N(G)-nitro-L-arginine methylester hydrochloride (L-NAME) partially abolished CE-induced apoptosis.

CONCLUSIONS

These findings suggested that exogenous and endogenous NO had a synergistic effect with substances in the tar phase to induce programmed cell death in gastric epithelial cells both in vivo and in vitro.