Dexmedetomidine Infusion Versus Placebo During Light or Deep Anesthesia on Postoperative Delirium in Older Patients Undergoing Major Noncardiac Surgery: A Pilot Randomized Factorial Trial.

BACKGROUND: Postoperative delirium (POD) is common among older surgical patients and may be affected by dexmedetomidine and depth of anesthesia. We designed this pilot study to assess the feasibility of comparing dexmedetomidine with normal saline during light versus deep anesthesia on POD in older patients undergoing major noncardiac surgery. METHODS: In this pilot randomized factorial study, 80 patients aged 60 years or older undergoing major noncardiac surgery were randomized (1:1:1:1) to receive dexmedetomidine infusion 0.5 µg/kg/h or normal saline placebo during light (bispectral index [BIS] target 55) or deep (BIS target 40) anesthesia. Feasibility end points included consent rate and dropout rate, timely enrollment, blinded study drug administration throughout surgery, no inadvertent unmasking, achieving BIS target throughout >70% of surgery duration, and the process of twice-daily POD screening. In addition, we estimated the POD incidences in the 2 control groups (placebo and deep anesthesia) and treatment effects of dexmedetomidine and light anesthesia. RESULTS: Between November 1, 2021, and June 30, 2022, 78 patients completed the trial (mean [standard deviation, SD] age, 69.6 [4.6] years; 48 male patients [62%]; dexmedetomidine-deep, n = 19; dexmedetomidine-light, n = 20; placebo-deep, n = 19; placebo-light, n = 20). This study had a high consent rate (86%) and a low dropout rate (2.5%). Average recruitment was 5 patients at each center per month. Dexmedetomidine and normal saline were administered in a blinded fashion in all patients. Unmasking did not occur in either group. Approximately 99% of patients received the scheduled study drug infusion throughout the surgery. Approximately 81% of patients achieved the BIS targets throughout >70% of the surgery duration. The scheduled twice-daily POD screening was completed without exception. Overall, 10 of the 78 patients (13%; 95% confidence interval [CI], 7%-22%) developed POD. For the 2 reference groups, POD was observed in 7 of the 39 patients (17.9%; 95% CI, 9%-32.7%) in the placebo group and 7 of the 38 patients (18.4%; 95% CI, 9.2%-33.4%) in the deep anesthesia group. Regarding the treatment effects on POD, the estimated between-group difference was -10% (95% CI, -28% to 7%) for dexmedetomidine versus placebo, and -11% (95% CI, -28% to 6%) for light versus deep anesthesia. CONCLUSIONS: The findings of this pilot study demonstrate the feasibility of assessing dexmedetomidine versus placebo during light versus deep anesthesia on POD among older patients undergoing major noncardiac surgery, and justify a multicenter randomized factorial trial.

MicroRNA-107: a novel promoter of tumor progression that targets the CPEB3/EGFR axis in human hepatocellular carcinoma.

MicroRNAs (miRNAs) are dysregulated in many types of malignancies, including human hepatocellular carcinoma (HCC). MiR-107 has been implicated in several types of cancer regulation; however, relatively little is known about miR-107 in human HCC. In the present study, we showed that the overexpression of miR-107 accelerates the tumor progression of HCC in vitro and in vivo through its new target gene, CPEB3. Furthermore, our results demonstrated that CPEB3 is a newly discovered tumor suppressor that acts via the EGFR pathway. Therefore, our study demonstrates that the newly discovered miR-107/CPEB3/EGFR axis plays an important role in HCC progression and might represent a new potential therapeutic target for HCC treatment.

Antitumor effects of mutant endostatin are enhanced by Bcl-2 antisense oligonucleotides in UM-UC-3 bladder cancer cell line.

BACKGROUND: Endostatin is a potent inhibitor of tumor angiogenesis. In the preliminary studies, we developed a mutant endostatin containing Arg-Gly-Asp-Arg-Gly-Asp (RGDRGD) sequences. In this study, we compared the antitumor effects of mutant endostatin and Bcl-2 antisense oligonucleotides both in combination and individually. METHODS: The artificially synthesized Bcl-2 ASODN (antisense oligonucleotides) included a translation-initiation site and was transfected into the bladder cancer cells by Lipofectamine. Cell growth was investigated by the tumor cell growth chart, MTT assay, caspase-3 activity detection assay, AO/EB fluorescein stain, and the annexin V-FITC apoptosis detection assay. In the in vivo study, UM-UC-3 bladder cancer cells were subcutaneously implanted into nude mice and the growth of tumor was examined. The ultrastructure of the tumor tissues in the treated and control groups were observed. RESULTS: The cell growth chart showed that the cell population of the treated combination group decreased by 52.04% compared to the control group. The inhibition rate of the treated combination group was (79.66 ± 6.79)%, whereas those of the individual ASODN and ES groups were (53.39 ± 3.22)% and (50.22 ± 5.46)% respectively. In the caspase-3 activity detection using AO/EB fluorescein stain and annexin V-FITC apoptosis detection assay, the co-inhibitory effect was higher than the individual inhibitory effects (P < 0.05). There were significant differences in the inhibition of the solid tumor growth in the in vivo study. CONCLUSIONS: Our findings indicated that Bcl-2 antisense oligonucleotides enhance the antitumor effects of mutant endostatin both in vitro and in vivo. We noted the synergistic effects of Bcl-2 antisense oligonucleotides combined with mutant endostatin.

[The genetic stability of recombinant adenovirus expressing human rotavirus VP6 gene which used Ad41 as vector].

OBJECTIVE: To investigate the genetic stability of non-replicating recombinant adenovirus which used Ad41 as vector and could express VP6 gene of group A rotavirus during continous passage, in order to develop the vaccine of rotavirus. METHODS: The recombinant adenovirus rvAd41-VP6 (o) was prepared by our laboratory early, it then was continuously propagated on 293TE7 cells for 14 passages. After that samples of the infected cells were collected at every 2 passages for the detection of the integration of the VP6 gene by PCR, and the expression of the target protein was detected by Western Blot analysis. RESULTS: Analysis by PCR revealed that, there was stable integration of specific VP6 gene in the rvAd41-VP6 (o), Western Blot analysis confirmed that rvAd41-VP6 (o) could stably expressed the group-specific antigen structural protein VP6 (o), and it had preferable genetic stability. CONCLUSION: The recombinant adenovirus rvAd41-VP6 (o) which could stably express the VP6 (o) gene had favorable biological property in vitro, and it has provided a basis for further research of animal immunization.

Replication and transcription of human papillomavirus type 58 genome in Saccharomyces cerevisiae.

BACKGROUND: To establish a convenient system for the study of human papillomavirus (HPV), we inserted a Saccharomyces cerevisiae selectable marker, Ura, into HPV58 genome and transformed it into yeast. RESULTS: HPV58 genome could replicate extrachromosomally in yeast, with transcription of its early and late genes. However, with mutation of the viral E2 gene, HPV58 genome lost its mitotic stability, and the transcription levels of E6 and E7 genes were upregulated. CONCLUSIONS: E2 protein could participate in viral genome maintenance, replication and transcription regulation. This yeast model could be used for the study of certain aspects of HPV life cycle.

Dendritic cells (DCs) transfected with a recombinant adenovirus carrying chlamydial major outer membrane protein antigen elicit protective immune responses against genital tract challenge infection.

Chlamydia trachomatis, an obligate intracellular bacterial pathogen, is the major cause of sexually transmitted diseases worldwide. Although a variety of strategies have been taken to promote the development of a protective vaccine, no ideal vaccine has been generated so far. In this study, we transfected dendritic cells (DCs) with recombinant adenovirus carrying C. trachomatis serovar E major outer membrane protein gene (Ad-MOMP), and investigated their ability to induce specific protection against genital tract chlamydial challenge infection. The results showed that when DCs were transfected with Ad-MOMP in vitro, the DCs exhibited increased expression of CD80 and MHC-II molecules as well as enhanced IL-12 secretion and were able to stimulate T-cell proliferation. The level of IFN-gamma secreted by stimulated T cells was also up-regulated significantly. When the Ad-MOMP transfected DCs were adoptively transferred intravenously to naive mice, they generated Th1-biased cytokine production and mucosal IgA responses specific for C. trachomatis. More importantly, the mice immunized with Ad-MOMP-DC mounted protection against genital tract challenge infection, shown by lower body mass loss, lower chlamydial loads, and less severe pathological changes. In conclusion, Ad-MOMP transfected DCs are capable of inducing effective protective immune responses against C. trachomatis genital infection.

Translational comparison of HPV58 long and short L1 mRNAs in yeast (Saccharomyces cerevisiae) cell-free system.

Recently, we developed a yeast cell-free system for translation of human papillomavirus (HPV) 58 short L1 mRNA and VLP assembly in vitro. In the present study, we examined the translation efficiency of HPV58 long and short L1 mRNAs in our established system. Production of HPV 58 long and short L1 proteins was significantly dependent on the amounts of the L1 mRNAs used and the time length of translation reaction. Compared with the long L1 mRNA, the short L1 mRNA consistently exhibited higher translation efficiency in all the experiments conducted. Supplementation of exogenous amino acids significantly enhanced translation of the long L1 mRNA in this system. Furthermore, a single amino acid leucine can be rate-limiting for translation of the long L1 mRNA in this system. Electron microscopy demonstrated that HPV 58 virus-like particles (VLPs) were assembled from both long and short L1 capsid proteins in the yeast cell-free system.

Constitutive activation of signal transducer and activator of transcription 3 regulates expression of vascular endothelial growth factor in human meningioma differentiation.

PURPOSE: Janus tyrosine kinases (JAKs) and signal transducer and activator of transcription factors (STATs), especially STAT3, are constitutively activated in human cancers. The function of STAT3 in the pathogenesis of meningioma remains unknown. In this study, we investigated the role of JAK1/STAT3 regulating vascular endothelial growth factor (VEGF) expression in the occurrence and progression of human meningioma. METHODS: We detected the expression of JAK1, p-JAK1, STAT3, p-STAT3, and VEGF in human meningioma and normal dura tissues by RT-PCR, Western blot analysis, and immunohistochemistry. RESULTS: JAK1, p-JAK1, STAT3, p-STAT3, and VEGF showed high expression in grade I and grade II meningioma. The level of STAT3 activation was associated with VEGF expression; all meningioma tumors that expressed p-STAT3 also expressed VEGF. Both frequency of positivity and expression were enhanced with increasing tumor grade; high frequencies and levels were found in grade II tumors, with no expression detected in normal dura tissues (P < 0.05). CONCLUSIONS: VEGF is directly regulated by constitutive STAT3 activity and associated with meningioma differentiation. STAT3 has an important role in the occurrence and development of human meningioma by regulating VEGF expression.

Mutational analysis of proto-oncogene Dbl on Xq27 in testicular germ cell tumors reveals a rare SNP in a patient with bilateral undescended testis.

OBJECTIVES: An abundance of X chromosomes in testicular germ cell tumors (TGCTs), and a candidate TGCTs susceptibility gene (TGCT1) on Xq27 highlight the potential involvement of X chromosomes in TGCT pathogenesis. However, the TGCT1 on Xq27 has so far not been identified. We hypothesized that a somatic mutation of dbl oncogene on Xq27 may play a role for the development of TGCTs. METHODS: We have screened 41 TGCT tissues for dbl mutations using single-strand conformation polymorphism (SSCP) analysis. These tissues are composed of 25 seminomatous TGCTs tissues and 16 non-seminomatous TGCTs tissues, including two cases with a rhabdomyosarcoma component. RESULTS: Somatic mutations were not detected in the 25 exons of dbl in these TGCTs. However, we found a rare single nucleotide polymorphism (SNP) (T to C nucleotide change) within intron 22 in one out of the 41 TGCTs cases (2%). Furthermore, the sample with the rare SNP was identified as the sole TGCTs case associated with bilateral undescended testis in our series. CONCLUSIONS: Our results indicate that proto-oncogene dbl is not a major target for sporadic TGCTs. However, the rare SNP in dbl may affect the susceptibility to undescended testis. Determining the frequency of this SNP in patients with various types of undescended testis in different ethnic groups is a warranted study.

Expression of HPV 58 long and short L1 capsid proteins in primary mouse keratinocyte cultures.

We studied expression of HPV 58 long and short L1 proteins in primary mouse keratinocyte (KC) cultures by transient transfection of the L1 expression constructs. Following transient transfection, long and short L1 open reading frames (ORFs) were transcribed continuously for 9 days; however, no significant difference was detected between the long and short L1 mRNA levels measured by quantitative RT-PCR. Western blot analysis showed that both long and short L1 proteins were continuously detected in L1-transfected KCs for 9 days post-transfection and the significantly increased signals of the L1 proteins over time were associated with KC differentiation. Moreover, L1 protein was more abundant in KCs transfected with the short L1 ORF than the long L1 ORF. In vitro translation of the L1 mRNAs indicated further that the short L1 mRNA had significantly higher translation efficiency than the long L1 mRNA in cell-free lysate system. The L1 proteins expressed from the two L1 mRNAs in KCs were similarly stable. Thus, approximate 40% lower level of expression of the L1 protein in KCs transfected with the long L1 ORF was probably due to a stem-loop structure with high DeltaG value downstream the first AUG codon in its mRNA secondary structure. This stem-loop structure might prevent efficient binding of the ribosome to mRNA and therefore reduced translation.

An optimized yeast cell-free system: sufficient for translation of human papillomavirus 58 L1 mRNA and assembly of virus-like particles.

We developed a yeast cell-free system suitable for in vitro translation of human papillomavirus 58 (HPV58) L1 mRNA. This system was systematically optimized resulting in enhanced translation efficiency. The optimal concentrations of potassium and magnesium ions observed were specific to the HPV58 L1 protein production. Supplementation with sucrose in the preparation of the yeast lysate greatly enhanced its stability. After optimization, protein production in this system was significantly superior to that produced by the rabbit reticulocyte (RRL) system. Finally, we demonstrated for the first time that virus-like particles (VLPs) were assembled from HPV58 L1 capsid protein in the yeast cell-free system. Thus, the system described here is a powerful tool for the HPV L1 protein production and will be useful for the study of VLP assembly and DNA encapsulation.

Periplocoside A, a pregnane glycoside from Periploca sepium Bge, prevents concanavalin A-induced mice hepatitis through inhibiting NKT-derived inflammatory cytokine productions.

Periploca sepium Bge, a traditional Chinese herb medicine, is widely used for treating rheumatoid arthritis in china. Periplocoside A (PSA), a pregnane glycoside, is a new nature product compound isolated from P. sepium Bge. We examined the protective effects of PSA, on concanavaline A (ConA)-induced hepatitis. Pretreatment with PSA dramatically ameliorated ConA-induced liver injury, which was characterized by reducing serum alanine transaminase (ALT), pathogenic cytokines of interleukin (IL)-4 and interferon (IFN)-gamma levels, impeding the liver necrosis, and thus elevating the survival rate. In vitro, PSA inhibited IL-4 and IFN-gamma productions of alpha-galactosylceramide (alpha-GalCer) or anti-CD3-activated Natural killer T (NKT) cells. Enzyme Linked Immunosorbent Assay (ELISA) and Reverse Transcription Polymerase Chain Reaction (RT-PCR) assays revealed PSA suppressed IL-4 transcription and IFN-gamma translation. In conclusion, PSA had significantly preventative effect on ConA-induced hepatitis, which was closely associated with inhibition of NKT-derived inflammatory cytokine productions. These findings suggested that PSA has the therapeutic potential for treatment of human autoimmune-related hepatitis.

Expression of nucleostemin in prostate cancer and its effect on the proliferation of PC-3 cells.

BACKGROUND: Nucleostemin is essential for the proliferation and survival of stem and cancer cells, but it is unknown whether this newly identified molecule is involved in prostate cancer pathogenesis. METHODS: Total RNA and protein were extracted from prostate cancer tissues and PC-3, LNCap and DU145 cell lines. The nucleostemin mRNA and protein expression were measured by RT-PCR and Western blot. Immunohistochemistry was also used to detect the nucleostemin protein expression in prostate cancer tissues and PC-3 cells. A nucleostemin specific, short hairpin RNA, expression plasmid was used to transfect PC-3 cells. The changes of nucleostemin gene were detected and the proliferative capacity of the cells was determined. RESULTS: Nucleostemin was highly expressed in prostate cancer tissues and cell lines. Nucleostemin expression level in the silencer group PC-3 cells remarkably reduced. The proliferation rate of silencer group PC-3 cells decreased and the percentage of G1 stage cells increased. The neoplasm forming capacity in nude mice of the silencer group PC-3 cells decreased significantly. CONCLUSIONS: Nucleostemin is highly expressed in prostate cancer tissues and cell lines. The proliferative capacity of PC-3 cells is remarkably reduced after silencing nucleostemin gene expression.

RbAp48 is a critical mediator controlling the transforming activity of human papillomavirus type 16 in cervical cancer.

Although human papillomavirus (HPV) infections are the primary cause of cervical cancer, the molecular mechanism by which HPV induces cervical cancer remains largely unclear. We used two-dimensional electrophoresis with mass spectrometry to study protein expression profiling between HPV16-positive cervical mucosa epithelial H8 cells and cervical cancer Caski cells to identify 18 differentially expressed proteins. Among them, retinoblastoma-binding protein 4 (RbAp48) was selected, and its differentiation expression was verified with both additional cervical cancer-derived cell lines and human tissues of cervical intraepithelial neoplasia and cervical cancer. Suppression of RbAp48 using small interfering RNA approach in H8 cells significantly stimulated cell proliferation and colony formation and inhibited senescence-like phenotype. Remarkably, H8 cells acquired transforming activity if RpAp48 was suppressed, because H8 cells stably transfected with RbAp48 small interfering RNA led to tumor formation in nude mice. In addition, overexpression of RbAp48 significantly inhibited cell growth and tumor formation. This RbAp48-mediated transformation of HPV16 is probably because of the regulation by RbAp48 of tumor suppressors retinoblastoma and p53, apoptosis-related enzymes caspase-3 and caspase-8, and oncogenic genes, including E6, E7, cyclin D1 (CCND1), and c-MYC. In brief, RbAp48, previously unknown in cervical carcinogenesis, was isolated in a global screen and identified as a critical mediator controlling the transforming activity of HPV16 in cervical cancer.

[Inhibitory effect of silencing STAT3 gene with short hairpin RNA mediated by polyamidoamine dendrimers on growth of prostate cancer].

OBJECTIVE: To investigate the possibility of using generation 5 polyamidoamine dendrimers (G5-PAMAM-D) as gene vector for eukaryotic expression plasmid of siRNA in prostate carcinoma in vitro and vivo. METHODS: Firstly, eukaryotic expression vector of siRNA pSilencing 4.1-EGFP-shRNA, specific for enhanced green fluorescent protein (EGFP), pSilencing 4.1-STAT3-shRNA for signal transducers and activators of transcription 3 (STAT3) was constructed. pEGFP-C1 and pSilencing 4.1-EGFP-shRNA were cotransfected into prostate cancer cells PC-3 and 22Rv1 with G5-PAPAM-D as vector, and to observe silencing of EGFP. Next, pSilencing 4.1-STAT3-shRNA was transfected into PC-3 and 22Rv1 cells by G5-PAPAM-D, Western blotting and apoptosis staining was used to detect silencing of STAT3 and growth inhibition. Thirdly, BALB/C mice subcutaneous tumor model was made with PC-3 cells. Polyplex of G5-PAMAM-D and pSilencing 4.1-STAT3-shRNA was injected intratumorally. The tumor volume was measured and recorded. RESULTS: Fluorescence detection and Western blotting analysis demonstrated that G5-PAMAM-D was able to deliver Silencing 4.1-EGFP-shRNA and pSilencing 4.1-STAT3-shRNA into the two prostate cancer cell lines, and shRNA was expressed to induce silence of EGFP and STAT3. MTT results showed that proliferation of prostate cancer cells was suppressed by G5-PAMAM-D/pSilencing 4.1-STAT3-shRNA and induced apoptosis of PC-3 cells in vitro. Human prostate cancer in mice was successfully formed by inoculation of PC-3 cells into male BABL/C mice. In G5-PAMAM-D/pSilencing 4.1-STAT3-shRNA treated group, the tumor volume was shrank remarkably at 9 days after treatment and tumor growth was retarded compared with control groups. CONCLUSION: GS-PAMAM-D nanoparticles can be used to deliver plasmid vector expressing shRNA into prostate cancer cells effectively in vitro and vivo. It appears to be a promising gene vector for RNA interference therapy in prostate cancer.

Ganoderic acid T from Ganoderma lucidum mycelia induces mitochondria mediated apoptosis in lung cancer cells.

Ganoderma lucidum is a well-known traditional Chinese medicinal herb containing many bioactive compounds. Ganoderic acid T (GA-T), which is a lanostane triterpenoid purified from methanol extract of G. lucidum mycelia, was found to exert cytotoxicity on various human carcinoma cell lines in a dose-dependent manner, while it was less toxic to normal human cell lines. Animal experiments in vivo also showed that GA-T suppressed the growth of human solid tumor in athymic mice. It markedly inhibited the proliferation of a highly metastatic lung cancer cell line (95-D) by apoptosis induction and cell cycle arrest at G(1) phase. Moreover, reduction of mitochondria membrane potential (Delta psi(m)) and release of cytochrome c were observed during the induced apoptosis. Our data further indicate that the expression of proteins p53 and Bax in 95-D cells was increased in a time-dependent manner, whereas the expression of Bcl-2 was not significantly changed; thus the ratio of Bcl-2/Bax was decreased. The results show that the apoptosis induction of GA-T was mediated by mitochondrial dysfunctions. Furthermore, stimulation of the activity of caspase-3 but not caspase-8 was observed during apoptosis. The experiments using inhibitors of caspases (Z-VAD-FMK, Z-DEVD-FMK and Z-IETD-FMK) confirmed that caspase-3 was involved in the apoptosis. All our findings demonstrate that GA-T induced apoptosis of metastatic lung tumor cells through intrinsic pathway related to mitochondrial dysfunction and p53 expression, and it may be a potentially useful chemotherapeutic agent.

[VP22 enhances the immunological activity of human cytomegalovirus pp65 DNA vaccine: experimental study with mice].

OBJECTIVE: To construct the human cytomegalovirus (HCMV) pp65 DNA vaccine vector and VP22 and pp65 coexpressing vector. To evaluate and compare immunological effects in mice. METHODS: Twenty-one BALB/C mice were divided into 3 equal groups: pcDNA3.pp65 group undergoing injection of pcDNA3.pp65 as DNA vaccine, pVP22.pp65 group undergoing injection of pVP22.pp65, and control group undergoing injection of normal saline. HCMV pp65 expression vector pcDNA3.pp65, VP22 and pp65 coexpressing vector pVP22.pp65 were constructed by molecular biology methods. The vectors were immunized into BALB/C mice as DNA vaccines. The T cell proliferation activity and IL-2 biological activity were determined using MTT method. NK activity was detected using LDH release test. The serum IgM and IgG levels of HCMV, the concentrations of IL-2 and IL-4 in serum and supernatant of spleen cells were detected using ELISA method. RESULTS: The HCMV DNA vaccine expression vectors were successfully constructed. Some indexes of the two vaccine groups (pcDNA3.pp65 and pVP22.pp65), that is, T cell proliferation activity (5.11 and 5.55 for SI at 8th week respectively), NK activity (8.74% and 12.08% at 12th week respectively), IgM level (1.20 and 1.58 for A value at 6th week respectively) and IgG level (1.09 and 1.78 for A value at 6th week respectively) were higher than those of negative control, and pVP22.pp65 group was higher than pcDNA3.pp65 group (P < 0.05). The concentrations of IL-2 and IL-4 and the IL-2 biological activity were very low in sera of three groups which showed no significant difference between them (P > 0.05), but higher in the spleen supernatant and the pVP22.pp65 group was highest (411.11 pg/ml, 76.10 pg/ml for the concentrations of IL-2 and IL-4 and 0.22 for IL-2 biological activity). CONCLUSION: The HCMV pp65 could induce certain immunological activity, and VP22 could significantly enhance pp65 in vivo immunological activity.

Analysis of synonymous codon usage bias in Chlamydia.

Chlamydiae are obligate intracellular bacterial pathogens that cause ocular and sexually transmitted diseases, and are associated with cardiovascular diseases. The analysis of codon usage may improve our understanding of the evolution and pathogenesis of Chlamydia and allow reengineering of target genes to improve their expression for gene therapy. Here, we analyzed the codon usage of C. muridarum, C. trachomatis (here indicating biovar trachoma and LGV), C. pneumoniae, and C. psittaci using the codon usage database and the CUSP (Create a codon usage table) program of EMBOSS (The European Molecular Biology Open Software Suite). The results show that the four genomes have similar codon usage patterns, with a strong bias towards the codons with A and T at the third codon position. Compared with Homo sapiens, the four chlamydial species show discordant seven or eight preferred codons. The ENC (effective number of codons used in a gene)-plot reveals that the genetic heterogeneity in Chlamydia is constrained by the G+C content, while translational selection and gene length exert relatively weaker influences. Moreover, mutational pressure appears to be the major determinant of the codon usage variation among the chlamydial genes. In addition, we compared the codon preferences of C. trachomatis with those of E. coli, yeast, adenovirus and Homo sapiens. There are 23 codons showing distinct usage differences between C. trachomatis and E. coli, 24 between C. trachomatis and adenovirus, 21 between C. trachomatis and Homo sapiens, but only six codons between C. trachomatis and yeast. Therefore, the yeast system may be more suitable for the expression of chlamydial genes. Finally, we compared the codon preferences of C. trachomatis with those of six eukaryotes, eight prokaryotes and 23 viruses. There is a strong positive correlation between the differences in coding GC content and the variations in codon bias (r=0.905, P<0.001). We conclude that the variation of codon bias between C. trachomatis and other organisms is much less influenced by phylogenetic lineage and primarily determined by the extent of disparities in GC content.

[Receptor-binding ability of fragments 260-600 and 397-796 of SARS-associated coronavirus spike protein].

BACKGROUND: To investigate the interaction between the host cell and the truncated S fragments to identify the receptor-binding domain of the spike (S) protein of SARS-associated coronavirus (SARS-CoV). METHODS: Two different fragments S260-600 and S397-796 of the SARS-CoV S protein were expressed in Escherichia coli (E.coli) using a pET expression vector, respectively. The two recombinant proteins were separately verified by Western blot, purified by nickel-affinity chromatography, and incubated with Vero cells, a susceptible cell line of SARS-CoV infection, for cell binding assay. After the sequential probing with sera from convalescent SARS-patients and FITC-labeled anti-human IgG, the cells were analyzed by flow cytometry. The NIH 3T3 cell, a non-permissive cell line of SARS-CoV infection, was used as controls. RESULTS: The recombinant proteins S260-600 and S397-796 were efficiently expressed in an insoluble form in E.coli. The appropriate expression of the proteins was confirmed by Western blotting using both SARS patients' sera and anti-6 x histidine antibody. The flow cytometry results showed that the both proteins were able to bind Vero cells, but the binding ability of S260-600 was somewhat stronger than that of S397-796. In contrast, the S260-600 protein did not bind NIH3T3 cells. CONCLUSION: Both S260-600 and S397-796 exhibited different receptor binding activity. The S260-600 fragment probably contains the important receptor binding domain and could be a potential candidate for the development of SARS vaccine and anti-SARS therapeutics.

tRNASer(CGA) differentially regulates expression of wild-type and codon-modified papillomavirus L1 genes.

Exogenous transfer RNAs (tRNAs) favor translation of bovine papillomavirus 1 wild-type (wt) L1 mRNA in in vitro translation systems (Zhou et al. 1999, J. Virol., 73, 4972-4982). We, therefore, investigated whether papillomavirus (PV) wt L1 protein expression could be enhanced in eukaryotic cells following exogenous tRNA supplementation. Both Chinese hamster ovary (CHO) and Cos1 cells, transfected with PV1 wt L1 genes, effectively transcribed the genes but did not translate them. However, L1 protein translation was demonstrated following co-transfection with the L1 gene and a gene expressing tRNA(Ser)(CGA). Cell lines, stably transfected with a bovine papillomavirus 1 (BPV1) wt L1 expression construct, produced L1 protein after the transfection of the tRNA(Ser)(CGA) gene, but not following the transfection with basal vectors, suggesting that tRNA(Ser)(CGA) gene enhanced wt L1 translation as a result of endogenous tRNA alterations and phosphorylation of translation initiation factors elF4E and elF2alpha in the tRNA(Ser)(CGA) transfected L1 cell lines. The tRNA(Ser)(CGA) gene expression significantly reduced translation of L1 proteins expressed from codon-modified (HB) PV L1 genes utilizing mammalian preferred codons, but had variable effects on translation of green fluorescent proteins (GFPs) expressed from six serine GFP variants. The changes of tRNA pools appear to match the codon composition of PV wt and HB L1 genes and serine GFP variants to regulate translation of their mRNAs. These findings demonstrate for the first time in eukaryotic cells that translation of the target genes can be differentially influenced by the provision of a single tRNA expression construct.