Natural history and factors associated with ulnar-sided wrist pain in distal radial fractures treated by plate fixation

We documented longitudinal changes in the incidence of ulnar-sided wrist pain after distal radial fractures treated by plate fixation and identified factors associated with ulnar-sided wrist pain. A total of 140 patients were enrolled in this study. Radiographs were taken 3 months after operation, and were used to measure radial inclination, anterior angulation and ulnar variance, and to identify the presence of an ulnar styloid fracture. Clinical assessments at the same time included grip strengths, ranges of wrist motion and the patient-rated wrist evaluation questionnaire. The presence of ulnar-sided wrist pain was noted at each follow-up visit. The incidence of ulnar-sided wrist pain decreased significantly with time after surgery (22 patients at 3 months, 11 patients at 6 months and three patients at 12 months). The mean age, sex, the presence of an ulnar styloid fracture and the classification of the distal radial fracture were not factors that were associated with a higher incidence of ulnar-sided wrist pain, but there was an association between higher patient-rated wrist evaluation scores and the presence of ulnar-sided wrist pain.

LEVEL OF EVIDENCE

Prognosis, Level IV.

Wolbachia screening in spiders and assessment of horizontal transmission between predator and prey

Recent studies have revealed that the prevalence of Wolbachia in arthropods is attributable not only to its vertical transmission, but also to its horizontal transfer. In order to assess the horizontal transmission of Wolbachia between predator and prey, arthropods belonging to 11 spider families and six insect families were collected in the same field of rice. The distribution of Wolbachia in these arthropods was detected by diagnostic PCR amplification of the wsp (Wolbachia outer surface protein gene) and 16S rDNA genes. Nurscia albofasciata Strand (Araneae: Titanoecidae), Propylea japonica Thunberg (Coleoptera: Coccinellidae), Paederus fuscipes Curtis (Coleoptera: Staphylinidae), and Nilaparvata lugens Stal (Homoptera: Delphacidae) were infected with Wolbachia. This is the first report of infection of N. albofasciata and P. fuscipes by Wolbachia. No direct evidence indicated the existence of horizontal transmission of Wolbachia between predator and prey.

Identification of genetic polymorphisms in bovine mitochondrial deoxyribonucleic acid

In this study, the intent was to identify genetic polymorphisms of mitochondrial (mt) DNA in Korean cattle (Bos taurus coreana) and to analyze the genetic relationship between Korean cattle and other breeds. Whole mtDNA genomes (16,338 bp) of 26 animals (16 Korean cattle and 10 Holsteins) were directly sequenced. Multiple alignments, including 26 whole-mtDNA sequences obtained by direct sequencing and 10 mtDNA sequences from a public database (National Center for Biotechnology Information), revealed 393 mtDNA polymorphisms (382 SNP, 3 heteroplasmies, and 8 insertion-deletion polymorphisms). Estimated gene diversity of mtDNA was 0.00198 among these 36 animals. Phylogenic analysis with mtDNA polymorphisms revealed a distinct genetic difference between Bos taurus (Korean, Japanese Black, Holstein, and Fleckvieh breeds) and Bos indicus (Nellore and Zwergzebu breeds). The genetic information regarding mtDNA polymorphisms identified in this study would be useful for further investigation of mtDNA in other breeds.

Employment status and work-related difficulties in family caregivers of terminal cancer patients compared with the general population

9580

Background: This study was aimed to investigate the employment status and work-related difficulties among family caregiver of terminal cancer patients compared with the general population. Methods: A survey was administered to 381 family caregivers of terminal cancer patients at 11hospitals and 994 general populations aged more than 18 years. Results: Family caregivers of terminal cancer patients were female (66.7%) and the patient's spouse (50.9%), with mean age of 46.8years (SD, 13.5). 212(56.1%) were working before cancer diagnosis, however, only 133(36.3%) continued working currently. Compared with the general population, 233(63.7%)family caregivers of terminal cancer patients were more likely to be not working (adjusted odds ratio [aOR] =2.39; 95% confidence interval [95%CI] = 1.73 to 3.29).Those who continued working reported more easy fatigability (40.6% vs 22.4%) and reduced working hours (20.3% vs 2.1%) than general population. For those doing housework, caregiving itself (56.4%) were identified to be the most common difficulties, followed by easy fatigability (32.3%). Major reasons for not working were providing care to the terminal cancer patients (24.0%). Older age (aOR=10.37; 95%CI=2.80 to 38.41), female sex (aOR=4.28; 95%CI=2.25 to 8.13), lower household income (aOR=2.19; 95%CI=1.19 to 4.06), bearing medical cost by other than spouse (aOR=2.10; 95%CI=1.05 to 4.19), and low performance status of the patients (aOR=2.00; 95%CI=1.01 to 3.95) were significantly associated with not working. Conclusions: When compared to the general population, family caregivers of terminal cancer patients were at risk job loss from their caregiving burden, and caregiving and easy fatigability were the major work-related difficulties. Our study might help make a strategy to reduce job loss for family caregivers' caregiving burden.

No significant financial relationships to disclose.

Study of anxiety and depression in cervical cancer survivors

e20644

Background: Cervical cancer is the second leading cause of cancer related deaths among women in Korea. However, few studies have been conducted to elucidate the psychological distress of this population. This study aimed to examine the prevalence of anxiety and depression among cervical cancer survivors, and to identify factors associated with such caseness. Methods: A total of 832 cervical cancer survivors recruited from six large hospitals in Korea completed a mailed survey, which included the Hospital Anxiety and Depression Scale (HADS), European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30, and QLQ-CX24. Anxiety and depression were defined by a score of ≥ 8 on the HADS subscales. With a framework that included socio-demographic, clinical, and symptom characteristics, multivariate logistic regression models were used to identify factors associated with anxiety and depression. Results: Among cervical cancer survivors, 34.3% reported HADS-defined anxiety and 39.7% reported HADS-defined depression. Anxiety was associated with having a lower income (OR=1.95, p=.021), smoking (OR=2.42, p=.002), poor body image (OR=3.26, p<.001), peripheral neuropathy (OR=2.21, p=.002), menopausal symptoms (OR=2.02, p=.004), and sexual inactivity (OR=2.35, p=.001). Depression was associated with younger age (OR=1.75, p=.006), having a lower income (OR=2.14 p<.001), drinking (OR=1.56, p=.050), poor body image (OR=4.59, p<.001), peripheral neuropathy (OR=2.34, p<.001), and sexual inactivity (OR=2.68, p=.002). Both anxiety and depression were influenced by socio-demographic factors, health behaviors, and cervical cancer-specific symptom characteristics rather than cancer- or treatment-related factors. Conclusions: Anxiety and depression were highly prevalent among cervical cancer survivors in Korea. This examination of risk factors for anxiety and depression will be helpful for the development of clinical management strategies in cervical cancer survivors.

No significant financial relationships to disclose.

The use of complementary and alternative medicine in patients with terminal cancer in Korea: Nationwide cross-sectional study

19534

Background: Although the use of complementary and alternative medicine(CAM) is widespread among patients with chronic diseases including cancer, little is known about CAM use in terminal cancer patients. Methods: This study included 4,042 families of cancer patients who died at 17 hospitals in Korea between January and December 2004. We conducted with telephone survey to decedents’ families. The response rate was 41.1%. The questionnaire included whether cancer patients had used CAM during last one year before death, type of modality, motivation for use, attitudes to CAM, and consultation with doctors. Results: CAM use of cancer patients was reported by 36.3% (604 of 1,662) and the average rate of CAM cost was 32% of total medical costs during one year before patient’s death. CAM use was more likely to death at hospitals (adjusted Odds Ratio: 1.35, 95% Confidential Interval: 1.15–1.58), residence in rural (aOR:1.26, 95%CI:1.08–1.47), need consultations about care (aOR:1.65, 95%CI:1.30–2.09) and religious support (aOR:1.3, 95% CI:1.11–1.53), diagnosis except liver/gallbladder cancer (aOR:0.67, 95%CI:0.55–0.81), and longer disease period (aOR:1.85, 95% CI:1.5–2.2). Use was greatest for mushrooms (41.6%), vegetable juice (25.6%), ginseng (21.8%) and Chinese medicine (16.4%). The motivation for CAM use was the recommendations from family members or friends (83.5%) and internet or advertisement (16.1%) but physicians’ recommendation or education (1.4%) was rare. The 37.4% of families of CAM-used patients were satisfied with CAM because of but feeling better or comfortable (79.3%), not cure (5.4%). And otherwise, the 62.1% of them were unsatisfied with CAM because of no effect (87.3%). Only 41.7% CAM users consulted with their physician. Conclusions: This study revealed a high prevalence of CAM use among terminal cancer patients without recommendation from doctors. Medical staffs should evaluate patients’ CAM use and inform accurately about CAM to terminal cancer patients and family for quality of care improvement.

No significant financial relationships to disclose.

Cervical cancer patients’ preferences and use of various cancer information sources in South Korea

16073

Background: Accessing appropriate facts is important in enabling cancer patients cope with the disease. This study focused on the utilization and preferences of cancer information sources by cervical cancer patients in terms of ease in receiving and searching the available data. Methods: The study included 830 women over the age of 18 years treated for cervical cancer at six hospitals in South Korea between 1983 and 2004. All the participants provided written informed consent, and the Institutional Review Board of the National Cancer Center approved the protocol. A questionnaire addressed the patients’ use of and preferences for sources and forms of cancer information. Data were collected by mail. Results: Television and/or the radio were the the most frequently cited sources of cancer information by the middle and oldest age groups: 45–64 years (52.0%), =65 years (47.3%), while patients in the youngest age group (<45 years) used the Internet (38.8%). Booklets and/or pamphlets (24.0%) were the source of cancer information preferred by the youngest age group, while patients in the middle and oldest age groups preferred TV/radio: 45–64 years (35.7%) and =65 years (55.0%). Life notes and/or experiences (43.2%), that is, personal accounts, comprised the most easily understood form of information regardless of age group. Conclusions: Our findings indicate that cervical cancer patients’ utilization of and preferences for sources of cancer information vary according to patient age. Tailored educational materials that consider the users’ age and condition should be customized to best fit their specific preferences.

No significant financial relationships to disclose.

Work situation and work-related difficulties in stomach cancer survivors compared with the general population

9084

Background: We aimed to investigate the work situation and work-related difficulties among stomach cancer survivors compared with the general population. Methods: We enrolled 426 stomach cancer survivors diagnosed 2001 to 2003 from two hospitals and 994 members without a history of cancer selected randomly from a representative sample of Korea adults. We identified work situation and work-related difficulties in two groups using multivariate logistic regression. Results: An employment rate of stomach cancer survivors decreased from 66.2% to 53.1% at average 28 months after their diagnosis and it was lower than that of general population (63.5%). The primary reason for not-working in survivors were that they were easily fatigued (31.2%) and had limitations in physical functioning (13.0%). Examining work-related difficulties, 50.6% of survivors who were working at the time of survey reported that they were easily fatigued and 37.5% of survivors reported that their capacity of work decreased whereas only 22.4%, 10.6% of general population reported. Survivors had housework- related difficulties because they were easily fatigued (74.4%) and emotionally distressful (12.2%) whereas 58.0% and 4.0% of general population reported. Older age (adjusted odds ratio [aOR]=18.12; 95% confidence interval [CI]=6.59 to 49.81), female (aOR=5.30; 95% CI=7.37 to 31.31), low income (aOR=1.87; 95% CI=1.04 to 3.33), poor physical functioning (aOR=0.97; 95% CI=0.95 to 0.98) and total gastrectomy (aOR=2.40; 95% CI=1.26 to 4.60) were more likely to increase the likelihood of not working in stomach cancer survivors. Conclusions: Stomach cancer and its treatment had a negative impact on employment rate as previous studies with other type of cancer. Our study found that stomach cancer survivors had an experience not only work-related but also housework-related difficulties. This information on stomach survivors’ might be help to make a better plan for the intervention of stomach cancer survivors’ return to work.

No significant financial relationships to disclose.

Tyrosine phosphorylation-dependent yeast two-hybrid system for the identification of the SH2 domain-binding proteins

In this paper, we established a modified yeast two-hybrid system, which is specialized for the detection of SH2 domain-binding proteins. The employment of the SH2 domain-tyrosine kinase fusion protein as bait allowed the efficient identification of SH2 domain-binding proteins. The general applicability of the system was tested using various combinations of SH2-kinase fusion bait and prey. The results indicate that the system specifically detected the previously reported in vivo interactions between the SH2 domains and their binding partners. In addition, using this system, we found the interaction between the adaptor protein, Lad, and the SH2 domain of Grb2 or PLC-gamma1. The binding of Lad to Grb2 was further confirmed in mammalian cells by a co-immunoprecipitation study. The conclusion is that the established tyrosine phosphorylation-dependent yeast two-hybrid system provides a novel and efficient way to define the SH2 domain-binding molecules.

Through induction of juxtaposition and tyrosine kinase activity of Jak1, X-gene product of hepatitis B virus stimulates Ras and the transcriptional activation through AP-1, NF-kappaB, and SRE enhancers

Here, based on the recent finding of HBx (X-gene product of hepatitis B virus) as the inducer of Jak1, we investigated the mechanism for the HBx-mediated host cell regulation and found that (i) HBx associates specifically with Jak1 in vivo; (ii) HBx itself forms a dimer which leads to juxtaposition of associated Jak1 and subsequent activation of the tyrosine kinase activity of Jak1; (iii) HBx-mediated activation of the promoters containing AP-1-, NF-kappaB-, SRE-, and SIE-sites is dependent on the activation of Jak1; (iv) Jak1, once activated by HBx, induces Ras activity through recruitment of Grb2 and induces tyrosine phosphorylation of Raf1, but not shc. These findings show that previously reported functions of HBx, such as activation of multiple signaling pathways and transcriptional activation are attributable to HBx-mediated Jak1 activation.

Adaptor protein Lad relays PDGF signal to Grb2 in lung cells: a tissue-specific PDGF signal transduction

Lad was previously identified as an adaptor protein binding to the SH2 domain of Lck (1). Specific detection of Lad mRNA in lung cells, as well as, in T cells led us to investigate the signaling pathways regulating Lad in lung cells. We found that (i) upon PDGF stimulation, Lad expression is induced in lung cells, especially in the bronchial epithelial cells; (ii) Lad is tyrosine phosphorylated upon PDGF stimulation and is associated with PDGF receptor; (iii) upon PDGF stimulation, Grb2 is recruited to Lad in human embryonic lung cells; (iv) overexpression of Lad elevated AP-1 promoter activity by two- to threefold, whereas dominant negative Lad abrogated PDGF-dependent activation of AP-1 promoter. These results provide a novel mechanism of PDGF-dependent signaling, in which Lad acts as an adaptor in a tissue-specific manner, linking PDGF signal to Grb2 and subsequent activation of AP-1.

[The influence of malocclusion on self-esteem and personality of college student]

OBJECTIVE

To study the relationship among the different malocclusions and self-esteem and personality.

METHODS

Two hundred and forty college students with normal occlusion and different types of malocclusion were classified into four groups(class I, class II, class III and normal) by Angle's classification, Sixty students in each group. The first three groups had been divided into three subgroups respectively by IOTN: mild, moderate and severe, twenty students in each subgroup. Each subject was assessed by using the body-esteem scale (BES) and the Eysenck personality questionnaire (EPQ).

RESULTS

(1) the mean score on facial appearance subscale in BES of the normal group is significantly higher than that of moderate and severe subgroups in class II and class III groups; (2) the mean T score on E subscale in EPQ of the normal group is significantly higher than that of severe subgroups in class II and class III groups, and the mean T score on N subscale in EPQ of the normal group is significantly lower than that of severe subgroups in class II and class III groups; (3) There is a positive correlation between the mean score on facial appearance subscale in BES and the mean T score on E subscale in EPQ and a negative correlation between the mean score on facial appearance subscale in BES and the mean T score on N subscale in EPQ.

CONCLUSIONS

(1) The students with moderate and severe class II and class III malocclusion have lower self esteem about their facial appearance than normal students; (2) The trends of introverstion and astatic emotion are higher in students with severe class II and class III malocclusion than in normal students; (3) The higher self esteem about his (or her) facial appearance, the higher trends of extroversion and statical emotion he(or she) has; the lower self-esteem about his (or her) facial appearance, the higher trends of introversion and astatic emotion he (or she) has.

Human hepatitis B virus X protein is a possible mediator of hypoxia-induced angiogenesis in hepatocarcinogenesis

The hepatitis B virus (HBV)-encoded transcriptional activator HBV-X protein (HBx) was known to be involved in hepatocarcinogenesis. Hepatocarcinogenesis generally included an active angiogenesis that was mainly considered to be due to a local hypoxia in liver tissues. However, the exact mechanisms of HBx-induced hepatocarcinogenesis were poorly understood. In this study, we examined the role of HBx in the increased angiogenesis and the possible regulating mechanisms of HBx by hypoxia. We demonstrated that HBx stimulated the transcription of vascular endothelial growth factor (VEGF), a potent angiogenic factor, in HBx-stable transfectants. HBx-induced angiogenesis was confirmed by in vivo tumor angiogenesis assay, resulting in that the HBx transfectants increased the formation of new blood vessels compared to the control transfectants. Then, we demonstrated that the expression of HBx was enhanced after incubating HBV-infected hepatoma cells under hypoxia. Moreover, the activity of HBV enhancer 1 (Enh1) was increased when hepatoma cells transfected with the reporter plasmid containing HBV Enh1 were exposed to hypoxic conditions. These results strongly suggest that HBx may play a critical role in the hypoxia-induced angiogenesis through transcriptional activation of VEGF during hepatocarcinogenesis.

Direct interaction of the CD38 cytoplasmic tail and the Lck SH2 domain. Cd38 transduces T cell activation signals through associated Lck

CD38 ligation has been shown to induce activation of intracellular signaling cascade in T lymphocytes through a Lck-dependent pathway. However, it is not clear how Lck initiates the CD38-mediated signaling process. In the present study, we showed that CD38 and Lck were physically associated through the cytoplasmic tail and the Src homology 2 domain, respectively. This was evidenced by coimmunoprecipitation of Lck with CD38 and Lck with isolated CD38 cytoplasmic domain from T cell lysate, cell lysate of COS-7 cells cotransfected with cDNAs of Lck and CD38, or a mixture of in vitro translated CD38 and Lck. Because the CD38 cytoplasmic domain does not contain any tyrosine residue, the interaction should be independent of phosphotyrosine. The interaction was further confirmed by in vitro interaction between a purified Lck Src homology 2 domain and a nonphosphosynthetic peptide corresponding to the membrane proximal region of the CD38 cytoplasmic domain. In addition, CD38 ligation resulted in an elevated tyrosine kinase activity of the CD38-associated Lck and ultimate activation of interleukin-2 gene transcription. Furthermore, expression of a kinase-deficient Lck mutant suppressed interleukin-2 gene activation in a dose-dependent manner. These results strongly suggested that CD38 ligation indeed tranduced signals for T cell activation using its associated Lck.

Lad, an adapter protein interacting with the SH2 domain of p56lck, is required for T cell activation

T cell-specific Src family tyrosine kinase, p56lck, plays crucial roles in T cell differentiation, activation, and proliferation. These multiple functions of p56lck are believed to be conducted through the protein-protein interactions with various cellular signaling proteins. To clarify the mechanisms through which p56lck contributes to T cell signaling, we identified the proteins binding to the Src homology 2 (SH2) domain of p56lck through a tyrosine phosphorylation-dependent yeast two-hybrid screening. Subsequent characterization of positive clones revealed the presence of a protein of 366 aa named Lad (Lck-associated adapter protein), which is a potential murine homologue of previously reported TSAd, a T cell-specific adapter protein. Lad contains several protein-protein interaction domains including a zinc-finger motif, an SH2 domain, a proline-rich SH3 binding motif, and several phosphotyrosine sites. Furthermore, Lad was tyrosine phosphorylated and associated with p56lck in vivo and redistributed from cytoplasm to the plasma membrane in a T cell activation-dependent manner. Moreover in T cells, IL-2 promoter activity was enhanced upon coexpression of Lad but was inhibited by the coexpression of antisense Lad RNA. These characteristics of Lad suggest that Lad play an essential role as an adapter protein in p56lck-mediated T cell signaling.

Tumorigenicity of mouse thymoma is suppressed by soluble type II transforming growth factor beta receptor therapy

Many types of tumor cells overexpress transforming growth factor beta (TGF-beta), which is believed to promote tumor progression. We hypothesized that overexpression of the extracellular region of the type II TGF-beta receptor (soluble TbetaRII) would compete for or block TGF-beta binding to TbetaRs on immune cells, preventing TGF-beta-mediated immunosuppression and consequently resulting in the eradication of tumor cells. We tested this in the mouse thymoma cell line EL4, which has been reported to suppress cellular immunity by secreting a large amount of TGF-beta. Transduction of EL4 with recombinant retrovirus encoding soluble TbetaRII resulted in the secretion of heterogeneously glycosylated, 25 to 35 kDa truncated TbetaRII. Inoculation of 1 x 10(4) to 5 x 10(4) soluble TbetaRII-modified EL4 cells (EL4/Ts, EL4 cells transduced with recombinant retrovirus encoding soluble TbetaRII and neomycin resistance gene) s.c. to mice showed reduced tumorigenicity, as indicated by lower overall tumor incidence (7%, 1 of 14; P < 0.001) compared with unmodified EL4 (100%, 9 of 9) or vector-modified EL4 cells (EL4/neo, EL4 cells transduced with recombinant retrovirus encoding neomycin resistance gene; 100%, 4 of 4). Administration of mitomycin C-treated EL4/Ts cells (1 x 10(6)) after EL4 inoculation (1 x 10(4)) reduced tumor incidence from 100% (5 of 5 in mice inoculated with mitomycin C-treated EL4/neo) to 40% (4 of 10, P < 0.05), indicating that supply of soluble TbetaRII could actually block TGF-beta-mediated tumorigenesis. In vitro tumor cytotoxicity assays revealed 3-5-fold higher cytotoxic activity with lymphocytes from EL4/Ts-bearing mice compared with those from EL4- or EL4/neo-bearing mice, indicating that the observed tumor rejection was mediated by restoration of the tumor-specific cellular immunity. These data suggest that expression of soluble TbetaRII is an effective strategy for treating highly progressive tumors secreting TGF-beta.

Expression and characterization of a novel plasminogen activator from Agkistrodon halys venom

A venom gland cDNA library of Agkistrodon halys was constructed and screened with a probe based on the consensus sequence of venomic serine proteases. Next, we determined the sequences of the entire open reading frames of two selected positives which were found to encode novel serine proteases of 234 and 233 amino acids in length and named as Haly-PA and Haly 2, respectively. Upon protein data base search, Haly-PA showed the highest similarity of 82% to the previously characterized plasminogen activator, TSV-PA (Zhang et al. 1995, J. Biol. Chem. 270, 10246- 10255). Haly 2 displayed a 78% similarity to beta-fibrinogenase (Hung et al. 1994, B. B. R. C., 205, 1707 1715). Haly-PA was successfully expressed using the baculovirus system and secreted into the culture media as a 32 kDa glycoprotein. In the western analysis of snake venom, anti-Haly-PA antibody detected the same size of band indicating that this enzyme is a component of snake venom. Recombinant Haly-PA was purified to homogeneity using the combination of anion exchange and gel filtration column. In the fibrino(geno)lytic assay, recombinant Haly-PA displayed an indirect fibrino(geno)lytic activity depending on the presence of plasminogen and cleaved the plasminogen to generate the active plasimin. These results indicate that Haly-PA is a plasminogen activator and displays fibrino(geno)lytic activity through conversion of plasminogen to plasmin.

Cloning and characterization of novel disintegrins from Agkistrodon halys venom

Snake venom disintegrins act as potent inhibitors of platelet aggregation. In this report, we isolated genes encoding novel members of disintegrins through the screening of Agkistrodon halys venom gland cDNA library. Subsequent characterization of positives revealed the presence of distinct disintegrins named salmosinl, 2, and 3, each containing a characteristic RGD/KGD sequence essential for the binding to integrins. Whereas salmosinl was identical to previously described salmosin purified from A. halys venom, salmosin2 and salmosin3 were predicted to be a novel, 73 amino acid protein with a KGD sequence, and an 80 amino acid protein with an additional 7th disulfide bond, respectively. Taken together, this is the first report describing 3 unique disintegrins, namely, salmosinl with RGD, salmosin2 with KGD and salmosin3 with 7 disulfide bonds are found in a single species of venom. Subsequently, to compare the platelet aggregation inhibitory potential of the recombinant protein with that of natural protein, salmosinl was expressed in E. coli and purified to homogeneity. Recombinant and natural salmosin1 inhibited the binding of alphaIIbbeta3 to fibrinogen with an almost identical IC50 value of 2.2 nM and 4.5 nM respectively. Moreover, recombinant salmosinl displayed an IC50 value approximately 5-fold lower than flavoridin, which was previously described as the most potent venom disintegrin so far. In conclusion, we identified 3 disintegrins with distinct properties through the molecular cloning approach and found that the recombinant salmosinl retained one of the most potent alphaIIbbeta3 antagonist activity.

Son of sevenless binds to the SH3 domain of src-type tyrosine kinase

To identify molecules which bind to the SH3 domains of p56lck, we screened a mouse T-cell lymphoma cDNA library using the yeast two-hybrid system. As a result, we obtained several positive clones including the Son of Sevenless gene which encodes a mammalian homolog of Drosophila Ras GDP/GTP exchange factor. In a subsequent analysis with the yeast two-hybrid system, Sos associated only with the constitutively active form of p56lck (F505) but not with wild type p56lck (Y505), indicating the requirement for an active conformation of p56lck for binding to Sos. Subsequently, we have demonstrated in vitro that the SH3 domain of p56lck as well as the proline-rich sequences of Sos are responsible for this association. In addition, the proline-rich domain of Sos also bound to the SH3 domains of other src-type tyrosine kinases, src and fyn, but not to that of PLC-gamma. More importantly, the p56lck SH3-Sos interaction was enhanced by serum stimulation, suggesting the possibility that the direct interaction between p56lck SH3 and Sos may contribute to the regulation of the Ras pathway.

HBx protein of hepatitis B virus activates Jak1-STAT signaling

The X-gene product (HBx) of the hepatitis B virus plays essential roles in viral replication and the generation of hepatocellular carcinoma. Although the mechanism for HBx action is unclear, HBx may exert its pleiotropic functions through the stimulation of signal transduction pathways including the Ras/mitogen-activated protein kinase cascade and/or inactivation of the p53 function. Here, we investigated whether HBx has the ability to activate the Jak-STAT signaling pathway. As a first step, we established stable cell lines constitutively expressing HBx. In these HBx-expressing stable cells, the tyrosine phosphorylation of various STATs, including STAT3 and -5, was constitutively enhanced by HBx, and the concomitant increase in STAT-dependent DNA binding and transcriptional activation was observed. Furthermore, HBx specifically elevated tyrosine phosphorylation and in vitro kinase activity of Jak1, but not Jak2 or Tyk2, through protein to protein interaction with Jak1. These results clearly establish HBx as the inducer of the Jak-STAT signaling pathway, and at the same time, HBx-mediated Jak-STAT activation may provide a novel mechanism for the pleiotropic functions of HBx, including transformation and promiscuous transcriptional activation.

Liver-specific enhancer II is the target for the p53-mediated inhibition of hepatitis B viral gene expression

Here, we established the inhibitory mechanism of p53 on hepatitis B viral gene expression using HepG2 cells. Our results are as follows. First, p53 down-regulated the activities of all four promoters of hepatitis B virus (HBV), suggestive of the presence of a common element mediating the p53-dependent transcriptional repression. Second, employing the 5'-deletion constructs of the pregenomic/core promoter, the liver-specific enhancer II region was localized as a target for the p53-mediated transcriptional repression. Third, in a detailed analysis of the enhancer II region, the 5'-proximal 31-base pair region was defined as a p53-repressible element. Throughout the study, p53-mediated repression was rescued upon coexpression of the X-gene product, HBx. Finally, in an electrophoretic mobility shift assay, the defined p53-repressible element did not bind purified p53 directly, but shifted three bands in HepG2 nuclear extract, two of which was supershifted upon addition of p53 monoclonal antibody. These results display a novel mechanism of p53-dependent transcriptional repression in which p53 negatively regulates the viral-specific DNA enhancer through protein to protein interaction with an enhancer-binding protein. At the same time, the results indicate that p53 plays a defensive role against HBV by transcriptionally repressing the HBV core promoter through liver-specific enhancer II and HBx is required to counteract this inhibitory function of p53.

Purification and molecular cloning of a platelet aggregation inhibitor from the snake (Agkistrodon halys brevicaudus) venom

A platelet glycoprotein IIb-IIIa (GP IIb-IIIa) antagonist, salmosin, was purified to homogeneity from Korean snake (Agkistrodon halys brevicaudus) venom by means of chromatographic fractionations. We have isolated the cDNA encoding salmosin by using the cDNA library of the snake venom gland and analyzed its complete nucleotide sequence. The molecular identity was confirmed by comparison of the deduced amino acid sequence with the directly determined primary structure of salmosin. This protein is a single-chain polypeptide composed of 73 amino acids including 12 cysteines as well as the sequence Arg-Gly-Asp, a proposed recognition site of adhesive proteins. The primary sequence of salmosin shows considerable homology to previously described proteins of snake venom GP IIb-IIIa antagonist family. A molecular mass of 7474 for the protein was determined by matrix-assisted laser desorption ionization mass spectrometry. Salmosin inhibits GP IIb-IIIa binding to immobilized fibrinogen with an IC50 of 2.2 nM and ADP-induced platelet aggregation with an IC50 of 131 nM, respectively. This work demonstrates the purification, characterization, and cDNA cloning of salmosin, a platelet aggregation inhibitor that may have therapeutic potential as an antithrombotic agent.

Characterization of satellite cells derived from chickens with the low score normal (LSN) muscle weakness

Myogenic satellite cell clones were established from the pectoralis major muscle of chickens with the low score normal (LSN) muscle weakness and controls. The percentage of cells which attached to substrata and began to proliferate was higher for the control line than the LSN line (55% vs 30%). Furthermore, of those clones which initiated growth, 63% of the control cells and only 32% of the LSN cells proliferated to confluence in 25 cm2 tissue culture flasks. Proliferation rates were significantly lower with LSN satellite cells than with controls (p < 0.05). LSN satellite cells were less responsive to the mitogenic effects of chicken serum (p < 0.05) and differentiation rates were lower compared with controls (p < 0.05). There was a greater (p < 0.05) number of insulin-like growth factor receptors on LSN satellite cells compared with controls. The IGF receptor binding affinities (Kds) between the two cell lines were similar (p > 0.05). The results suggest that a defect in satellite cell physiology may contribute to the skeletal muscle weakness seen in the LSN line.

X-gene product of hepatitis B virus induces apoptosis in liver cells

Hepatitis B virus is a causative agent of hepatocellular carcinoma, and in the course of tumorigenesis, the X-gene product (HBx) is known to play important roles. Here, we investigated the transforming potential of HBx by conventional focus formation assay in NIH3T3 cells. Cells were cotransfected with the HBx expression plasmid along with other oncogenes including Ha-ras, v-src, v-myc, v-fos, and E1a. Unexpectedly, the introduction of HBx completely abrogated the focus-forming ability of all five tested oncogenes. In addition, the cotransfection of Bcl-2, an apoptosis inhibitor, reversed the HBx-mediated inhibition of focus formation, suggesting that the observed repression of focus formation by HBx is through the induction of apoptosis. Next, to test unequivocally whether HBx induces apoptosis in liver cells, we established stable Chang liver cell lines expressing HBx under the control of a tetracycline-inducible promoter. Induction of HBx in these cells in the presence of 1% calf serum resulted in typical apoptosis phenomena such as DNA fragmentation, nuclear condensation, and fragmentation. Based on these results, we propose that HBx sensitizes liver cells to apoptosis upon hepatitis B virus infection, contributing to the development of hepatitis and the subsequent generation of hepatocellular carcinoma.

Variation in response to growth factor stimuli in satellite cell populations

Variation in response to growth factor stimuli in myogenic satellite cell populations was investigated using a clonal-derived satellite cell culture system. Satellite cell clones were established from one muscle from one individual animal. One clone ("Early") which reached confluence on day 19 and one clone ("Late"), which reached confluence on day 29, were chosen for further examination. In previous studies, these two clones were found to differ in their growth rates in serum-containing medium. In the present study, the influence of growth factors on the proliferation of the two clones was compared in serum-free defined medium. Although basic fibroblast growth factor (bFGF), insulin-like growth factor-I (IGF-I), insulin, and platelet-derived growth factor-BB (PDGF-BB) stimulated proliferation of both clones, the Early clone was more responsive to all growth factors tested than the Late clone (P < or = 0.05). The Early clone was also more responsive to the proliferative and differentiative depressing effects of administered transforming growth factor-beta (P < or = 0.05). Examination of properties of the PDGF, FGF, and IGF-I receptors on these two clones revealed no differences in either dissociation constants or receptor numbers (P > or = 0.05). The results suggest that there is heterogeneity in satellite cell response to growth factors.

Comparison of growth factor receptors and metabolic characteristics of satellite cells derived from the biceps femoris and pectoralis major muscles of the turkey

Myogenic satellite cells were isolated from the turkey pectoralis major (PM), a muscle composed largely of white fibers, and the biceps femoris (BF), a muscle composed largely of red fibers, and their properties were compared in culture. Satellite cells derived from the PM and BF muscles exhibited differences in metabolic parameters, growth factor receptor characteristics, and mitogenic responses. PM satellite cells exhibited greater responsiveness to platelet-derived growth factor (PDGF), and the PDGF receptor on these cells had a higher affinity toward ligand compared to BF cells (P < 0.05). Protein synthesis, protein degradation, and glucose uptake rates were higher in BF satellite cell cultures (P < 0.05), correlating with previously reported in vivo measurements using red and white muscle fibers.

X-gene product antagonizes the p53-mediated inhibition of hepatitis B virus replication through regulation of the pregenomic/core promoter

Employing the glutathione S-transferase column retention method and far Western analysis, we found a physical association between tumor suppressor p53 and the hepatitis B virus X-gene product, which led us to study the function of observed interaction in relation to viral propagation. In the cell culture-based in vitro replication system, expression of p53 resulted in dramatic inhibition of viral replication, and this inhibition was relieved by the coexpression of the X-gene product in a dose-dependent manner. Furthermore, the activity of pregenomic/core promoter, responsible for the synthesis of pregenomic RNA, was almost completely inhibited upon expression of p53, and as in the replication assay, the inhibition was rescued by the coexpression of the X-gene product in a dose-dependent manner. Based on these results, we propose that the ratio of X-gene product to p53 is an important factor determining the fate of viral replication through modulation of the pregenomic/core promoter.