Construction of pGFP-FL plasmid and its application in preparing FL-secreting tumor vaccine

OBJECTIVE

To construct a plasmid containing a green fluorescent protein (GFP) reporter gene as the effective vector for preparing fms-like tyrosine kinase receptor-3 ligand (FL)-secreting tumor vaccines.

METHODS

A pGFP-FL plasmid, harboring a FL gene and a GFP gene, was designed and constructed by routine molecular cloning techniques. In this plasmid, FL gene was under the control of cytomegalovirus promoter, while EF-1a promoter acted to drive GFP gene. A prokaryotic/eukaryotic selective gene Kan(R)/neo was also introduced into the plasmid. After structure identification by restriction analysis, pGFP-FL plasmid was further transferred into Hepa1-6 cells, and the expression of GFP and FL genes was examined by way of fluorescent microscopy and reverse transcriptase-PCR respectively.

RESULTS

Restriction analysis showed that the structure of pGFP-FL plasmid was exactly the same as anticipated. Further results indicated that both GFP and FL genes were simultaneously expressed in Hepa1-6 cells.

CONCLUSION

A new plasmid has been established as the vector for studying the FL-secreting tumor vaccines, in which GFP gene can serve as a reporter gene reflecting the expression of FL gene.

Inhibition of epidermal growth factor receptor tyrosine kinase by chalcone derivatives

In our previous study, butein, a chalcone derivative, was found to be an inhibitor of tyrosine kinases and the inhibition was ATP-competitive. In this work, chalcone and seven chalcone derivatives were used to analyse the relationship between the structure of these compounds and their inhibition of tyrosine kinase activity. Three of chalcone derivatives, including butein, marein and phloretin, were found to have an ability to inhibit the tyrosine kinase activity of epidermal growth factor receptor (EGFR) in vitro. IC(50) was 8 microM for butein, 19 microM for marein and 25 microM for phloretin. The structural characterisations of these inhibitors suggest that the hydroxylations at C4 and C4' of these molecules may be required for them to act as EGFR tyrosine kinase inhibitors. The inhibition of EGF-induced EGFR tyrosine phosphorylation by butein was also observed in human hepatocellular carcinoma HepG2 cells, while marein and phloretin were inactive at the doses tested. Molecular modelling suggests that butein, marein and phloretin can be docked into the ATP binding pocket of EGFR. Hydrogen bonds and hydrophobic interaction appear to be important in the binding of these inhibitors to EGFR.

[A comparison of chemical composition and bioactivity of polypeptides from velvet antlers of Cervus nippon Temminck and Cervus elaphus Linnaeus]

OBJECTIVE

To compare the chemical composition and bioactivity of polypeptides(PPs) isolated from velvet antlers of sika deer (Cervus nippon Temminck) and red deer (Cervus elaphus Linnaeus).

METHOD

The two kind of polypeptides were isolated from the above mentioned velvet antlers with same technology. The chemical composition was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and MALDI-TOF mass spectrometry. Stimulant activity of cells proliferation was measured by [3H] TdR incorporation into DNA.

RESULT

The graphs of SDS-PAGE and MALDI-TOF MS of velvet antler polypeptides (VAPPs) from Chinese and New zealand red deer were very similar, but there were obvious difference in respect of graph between sika deer and red deer. VAPPs 25-50 mg.L-1 showed marked proliferation-promoting activity for rabbit costed chondrocytes, either sika deer or red deer. However, the activity of sika deer VAPPs 12.5 mg.L-1 for epidermal cells was weaker than that of red deer (12.5 mg.L-1).

CONCLUSION

The chemical property and bioactivity of VAPPs from sika deer and red deer are significantly different.

[High level expression and purification of Cysticercosis cellulose annexin32 in Escherichia coli]

In previous work, the cDNA encoding Cysticercus cellulose annexin32 has been cloned. With PCR method, two different restriction Sites were added to each end of the cDNA respectively. Then, the cDNA was inserted into prokaryotic expression vector pJLA-503. After inducing, most foreign protein was expressed in soluble form, which was up to 35% of the total protein of the bacteria. Subsequently, the recombinant Annexin32 was purified with (NH4)2SO4 stepwise precipitation, DEAE-Sepharose FF and Sephacryl S-200 HR chromatography. The final pure protein can been shown as a single band in SDS-PAGE, and the biological activity was verified by Western blot and anticoagulation activity assay.

[Determination of shikimic acid in fruit of Illiciaceae plants by HPLC with diode-array detection]

OBJECTIVE

To establish the determination method of Shikimic acid.

METHOD

Using HPLC method as the determination method. The separation was performed in a SiO2-NH2 column with a mobile phase of Acetonitrile-2% H3PO4 water solution (95:5); The sample wavelength was 213 nm, reference wavelength 300 nm.

RESULT

The average collection was 98.5%, RSD 1.67% (n = 5).

CONCLUSION

This method is suitable for the determination of Shkimic acid in herb medicines and preparation containing shikimic acid.

[Cloning, high level expression and purification of porcine IFN gamma]

Peripheral blood lymphocytes from a single swine were stimulated with Concavadin A for 17 h, and the total RNA was isolated from it. Then, the mRNA specific for porcine IFN gamma was amplified by reverse transcription polymerase chain reaction. After sequencing, the IFN gamma gene has been successfully inserted into vector pJLA-503 and highly expressed in E. coli. Recombinant porcine IFN gamma expressed as inclusion body, which was dissolved in 7 mol/L guanidine chloride and subsequently renatured by dilution in refolding buffer containing 0.5 mol/L L-arginine. In order to obtain pure protein, the renatured IFN gamma was purified by the chromatographies of SP-Sepharose FF and Sephacryl S-200 HR. As a result, the final pure product can been seen as a single band in SDS-PAGE, and the cytokine activity was verified by inhibiting the cytopathic effect.

Apoptosis in oncology

Apoptosis is a complex process involving a large array of genes and mutation of any of these genes may lead to malignancy formation. Re-acquirement of FasL by tumor cells may enable them to evade the surveillance of immune system and thus contributes to the growth of tumor. Apart from traditional therapies, inducing apoptosis of tumor cell by new methods employing death receptor ligands and making use of Fas counterattack is also being developed.

[Isolation and identification of a noval polyphenolic compound from Phyllanthus urinaria L]

OBJECTIVE

To investigate the chemical constituents of Phyllanthus urinaria.

METHOD

Various chromatographic techniques were employed for isolation and purification. The structures were elucidated by spectral analyses.

RESULT AND CONCLUSION

A novel polyphenolic compound was isolated and named phyllanthusin F.

[Studies on chemical constituents of Phyllanthus urinaria L]

OBJECTIVE

To investigate the chemical constituents of Phyllanthus urinaria.

METHOD

Various chromatographic techniques were employed for isolation and purification of the constituents. The structures were elucidated by chemical and spectral analyses.

RESULT AND CONCLUSION

Fourteen compounds were isolated and seven of them were identified as corilagin(I), rutin(II), brevifolincarboxylic acid(VI), isostrictiniin(IX), geraniin (X), gallic acid(XI) and ellagic acid (XII). Compound VI was found from P. urinaria for the first time and compound IX was found from genus Phyllanthus for the first time.

Characterization of the pathogenicity of members of the newly established H9N2 influenza virus lineages in Asia

The reported transmission of avian H9N2 influenza viruses to humans and the isolation of these viruses from Hong Kong poultry markets lend urgency to studies of their ecology and pathogenicity. We found that H9N2 viruses from North America differ from those of Asia. The North American viruses, which infect primarily domestic turkeys, replicated poorly in inoculated chickens. Phylogenetic analysis of the hemagglutinin and nucleoprotein genes indicated that the Asian H9N2 influenza viruses could be divided into three sublineages. Initial biological characterization of at least one virus from each lineage was done in animals. Early isolates of one lineage (A/Chicken/Beijing/1/94, H9N2) caused as high as 80% mortality rates in inoculated chickens, whereas all other strains were nonpathogenic. Sequence analysis showed that some isolates, including the pathogenic isolate, had one additional basic amino acid (A-R/K-S-S-R-) at the hemagglutinin cleavage site. Later isolates of the same lineage (A/Chicken/Hong Kong/G9/97, H9N2) that contains the PB1 and PB2 genes similar to Hong Kong/97 H5N1 viruses replicated in chickens, ducks, mice, and pigs but were pathogenic only in mice. A/Quail/Hong Kong/G1/97 (H9N2), from a second lineage that possesses the replicative complex similar to Hong Kong/97 H5N1 virus, replicated in chickens and ducks without producing disease signs, was pathogenic in mice, and spread to the brain without adaptation. Examples of the third Asian H9N2 sublineage (A/Chicken/Korea/323/96, Duck/Hong Kong/Y439/97) replicated in chickens, ducks, and mice without producing disease signs. The available evidence supports the notion of differences in pathogenicity of H9N2 viruses in the different lineages and suggests that viruses possessing genome segments similar to 1997 H5N1-like viruses are potentially pathogenic in mammals.

Venom alkaloids of fire ants in relation to worker size and age

Piperidine alkaloids compose most of the venom of the red imported fire ant, Solenopsis invicta, and we examined how six of these alkaloids varied across worker size and age. In a colony sampled intensively, the relative abundance of each alkaloid was highly correlated with worker size with one exception, and ratios of saturated to unsaturated alkaloids were positively correlated with worker size. Similarly, both the abundance and ratios of alkaloids differed significantly between the small and large workers sampled from colonies across Texas, USA. Young and old workers produced less venom than ants of intermediate age (3-7 weeks), and ratios of saturated to unsaturated alkaloids increased significantly with worker age. The differences in venom composition correspond to the size- and age-based functional roles of workers.

Isolated cleft palate in mice with a targeted mutation of the LIM homeobox gene lhx8

Formation of the mammalian secondary palate is a highly regulated and complex process whose impairment often results in cleft palate, a common birth defect in both humans and animals. Loss-of-function analysis has linked a growing number of genes to this process. Here we report that Lhx8, a recently identified LIM homeobox gene, is expressed in the mesenchyme of the mouse palatal structures throughout their development. To test the function of Lhx8 in vivo, we generated a mutant mouse with a targeted deletion of the Lhx8 gene. Our analysis of the mutant animals revealed a crucial role for Lhx8 in palatogenesis. In Lhx8 homozygous mutant embryos, the bilateral primordial palatal shelves formed and elevated normally, but they often failed to make contact and to fuse properly, resulting in a cleft secondary palate. Because development of other craniofacial structures appeared normal, the impaired palatal formation in Lhx8-mutant mice was most likely caused by an intrinsic primary defect in the mesenchyme of the palatal shelves. The cleft palate phenotype observed in Lhx8-mutant mice suggests that Lhx8 is a candidate gene for the isolated nonsyndromic form of cleft palate in humans.

Chlorpromazine inhibits hepatocyte apoptosis caused by withdrawal of phenobarbital in mice

AIM

To study the inhibitory effect of chlorpromazine (Chl), verapamil, and aspirin on hepatocyte apoptosis induced by the cessation of phenobarbital (Phe) treatment in mice.

METHODS

Liver DNA content, ratio of liver weight/body weight, DNA fragmentation, DNA electrophoresis, the end-labeling test (TUNEL), and the morphologic changes of liver cells as indices of liver mass and hepatocyte apoptosis were applied to investigate (1) the kinetic process of hepatocyte proliferation induced by Phe 75 mg.kg-1 i.p. and the regression of hyperplastic liver caused by withdrawal of Phe in mice, (2) the effect of Chl 25 mg.kg-1, verapamil 50 mg.kg-1 or aspirin 60 mg.kg-1 i.p. on mouse hepatocyte apoptosis, and (3) the time course of effects of Chl on the regression of liver size and DNA fragmentation content after withdrawal of Phe.

RESULTS

The process of hepatocyte proliferation and regression induced by administration and withdrawal of Phe in mice consisted of 4 phases: proliferation, plateau, rapid regression, and slow regression phases. In the rapid regression phase, the typic changes of hepatocyte apoptosis were found, which was prevented in early period by the Ca(2+)-calmodulin antagonist Chl, but not by verapamil or aspirin.

CONCLUSION

The Ca(2+)-calmodulin played an important role in the hepatocyte apoptosis caused by withdrawal of Phe.

Antagonistic effects of shikimic acid against focal cerebral ischemia injury in rats subjected to middle cerebral artery thrombosis

AIM

To study the effects of shikimic acid (SA) on focal cerebral ischemic injury after middle cerebral artery thrombosis (MCAT).

METHODS

Thrombosis was induced by FeCl3 in middle cerebral artery of rats. The influences of SA on neurologic deficit (ND), infarct size (IS), brain edema, and cerebral blood flow (CBF) in ischemic region were observed.

RESULTS

SA 25 and 50 mg.kg-1 i.p. for 3 d before MCAT attenuated ND, and reduced IS by 51% and 42%; and decreased brain water content from 80.7% to 79.8% and 79.9%; and increased CBF after ischemia from 50.2% of the preischemic level to 75.5% and 73.3%, respectively. In pathologic examination, there was much less thrombosis in MCA in the rat with the pretreatment by SA 25 mg.kg-1. The extent of brain ischemia was much less than that of control.

CONCLUSIONS

SA reduced focal cerebral ischemic injury induced by middle cerebral artery thrombosis.

Velvet antler polypeptides promoted proliferation of chondrocytes and osteoblast precursors and fracture healing

AIM

To study the effects of velvet antler (VA) total polypeptides (VATP) and VA polypeptides, VAP-A, VAP-B, and VAP-C on proliferation of chondrocytes and osteoblast precusors.

METHODS

Chondrocytes (rabbit and human fetus) and osteoblast precusors (chick embryo) were incubated in the culture medium containing VATP or VAP-A, VAP-B, and VAP-C. [3H]TdR incorporation into DNA was measured. Fracture healing-promoting action of VATP was determined in rats.

RESULTS

VATP 50-200 mg.L-1 and VAP-B 12.5, 25, and 50 mg.L-1 showed most marked proliferation-promoting activity for rabbit costed chondrocytes and increased incorporation of [3H]TdR from (73 +/- 9) Bq (control group) to (272 +/- 55), (327 +/- 38), and (415 +/- 32) Bq, respectively (P < 0.01). The activity of VAP-A was weaker than that of VAP-B, and VAP-C had no activity. VATP 10 and 20 mg.kg-1 by local injection into the cross-section fracture area accelerated healing of radial fracture. The healing rate of VATP-treated group was higher (75%) than that of control group (25%) (P < 0.05).

CONCLUSION

VATP accelerated fracture healing by stimulating proliferation of chondrocytes and osteoblast precursors.

Induction of hepatocyte proliferation and prevention of hepatocyte apoptosis by phenobarbital related to local humoral factor in mouse liver

AIM

To study the association of phenobarbital (Phe) inducing hepatocyte proliferation and blocking hepatocyte apoptosis with local humoral factor in liver.

METHODS

The ratio of liver/body weight, DNA content, regressive rate of hyperplastic liver, and DNA fragmentation were used to investigate whether the Phe-treated mouse liver extract (PMLE) and PMLE-95 (PMLE heated at 95 degrees C for 30 min) possessed Phe-like effects on mouse liver. Meantime, the effects of pretreatment with trypsin, RNAase, and DNAase on the activity of PMLE-95 were observed, and the differences of components between PMLE-95 and NMLE-95 (normal mouse liver extract, NMLE heated at 95 degrees C for 30 min) were analyzed with HPLC.

RESULTS

PMLE-95 stimulated hepatocyte proliferation and prevented hepatocyte apoptosis caused by withdrawing Phe in mice, and the activity of PMLE-95 was eliminated after the pretreatment with trypsin. On the chromatograms PMLE-95 had 5 main peaks, while NMLE-95 had only 4 peaks.

CONCLUSION

The effects of Phe on the liver were mediated by an intrinsic protein or peptide substance produced in response for the stimulation of Phe in mouse liver.

Population profile of stable flies (Diptera: Muscidae) caught on Alsynite traps in various feedlot habitats

Cylindrical traps made from Alsynite fiberglass were placed in 4 habitats in a confined cattle feedlot environment from 2 May to 30 October 1996 to evaluate abundance, sex ratio, physiological age structure, and blood-fed status of trapped adult stable flies, Stomoxys calcitrans (L.). Significantly more stable flies were caught on the trap located between host cattle and trees. The abundance of stable flies decreased geometrically with increasing distance from the host cattle in the open area. The spatial distribution of adult flies in cattle feedlot habitats became less heterogeneous as the population density increased. Male stable flies clearly dominated the total collection (66.7:33.3, male:female). A higher proportion (38.9%) of female stable flies was found on the trap close to a major immature developing area (manure pile). Most of the trapped flies (64.8%) showed a positive blood-fed status, but only 331 (8.8%) of 3,767 flies had recently fed. A majority (72.6%) of the attracted females was at the early nulliparous stage. Trap positioning did not have any significant influence on specific physiological age groups of the captured flies.

Serum and egg yolk IgG antibody titers from laying chickens vaccinated with Pasteurella multocida

Through determining the serum and egg yolk antibody titers in immunized laying hens to Pasteurella multocida regularly, the growth-decline trend of the egg yolk antibody levels was found to be similar to that of the serum antibody levels (r = 0.94), but the growth and decline of the egg yolk antibody seemed to be delayed 3-6 days compared with that of the serum antibody, and the egg yolk antibody titers were generally lower than those of the serum antibody (P < 0.01). Serum and egg yolk antibody levels declined 3 and 6 days, respectively, after booster immunizations. The higher the antibody levels were before booster immunization, the more they declined.

[A strain of A/PR/8/34 (H1N1)-like virus isolated from men]

An influenza virus was isolated in May, 1991 from a child with acute respiratory disease. The identification results with serologic method have revealed that the isolate was A/PR/8/34 (H1N1)-like virus. The analyses of nucleotide sequences in HA1 domain showed that there were 12 different positions on nucleotide sequences between the isolate and the A/PR/8/34 (H1N1) virus. These differences induced substitutions of 4 amino acids in HA1 protein molecule of isolate as compared with that of A/PR/8/34 (H1N1) virus. The oligonucleotide analyses of viral genome revealed that there were 11 different points between isolate and A/PR/8/34 (H1N1) virus, e. g. 2 deleted and 9 inserted in genome of isolate as compared with A/PR/8/34 (H1N1) strain. Therefore, the isolate possibly derived from A/PR/8/34 (H1N1) virus by laboratory contamination could be ruled out. However, where did A/Guangdong/6/91 (H1N1) virus come from? This question will be settled by further study.

Effective tumor vaccines generated by in vitro modification of tumor cells with cytokines and bispecific monoclonal antibodies

Antitumor immune responses are mediated primarily by T cells. Downregulation of the major histocompatibility complex (MHC) and the molecules that costimulate the immune response is associated with defective signaling by tumor cells for T-cell activation. In vitro treatment with a combination of cytokines significantly increased the expression of MHC class I and adhesion molecules on tumor cell surfaces. When tumor cells were first incubated with a bispecific monoclonal antibody that binds antigen on tumor cells to CD28 on T cells, the modified tumor cells become immunogenic and are able to stimulate naive T cells, generating tumor-specific cytotoxic T cells in vitro. Immunization with the modified tumor cells elicits an immune response mediated by CD8+ T cells. This response protected against a challenge with parental tumor cells and cured established tumors. The approach was effective in both low immunogenic and nonimmunogenic tumor model systems. Modification of tumor cells with this two-step procedure may provide a strategy for development of tumor vaccines that is effective for cancer immunotherapy.

Canine H(+)-K(+)-ATPase alpha-subunit gene promoter: studies with canine parietal cells in primary culture

H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) is the principal enzyme responsible for the process of gastric acid secretion. This enzyme is expressed in a cell-type-specific manner in gastric parietal cells. To explore the mechanisms regulating its expression, we transfected differentiated canine parietal cells in primary culture with H(+)-K(+)-ATPase-luciferase reporter genes and assessed transcriptional activities. Deletional analysis of the 5'-flanking region of this gene demonstrated a remarkable increment in transcriptional activity associated with a segment between bases -54 to -45 (5' GCTCCGCCTC 3') relative to the transcriptional initiation site. Gel shift assays with competition and supershift analysis demonstrated that this segment is specifically bound by the transcription factor Sp1. A point mutation, eliminating Sp1 binding, diminished basal transcriptional activity by 80%, indicating that this Sp1 binding site is important for constitutive transcriptional activity. Although these studies indicate that Sp1 is required to maintain a high concentration of the H(+)-K(+)-ATPase gene in the parietal cell, its cell-type-specific expression must rely on other elements because Sp1 is a ubiquitously expressed transcription factor.

Altered expression of CD44 in human prostate cancer during progression

There is a great need for markers that distinguish slowly progressive from rapidly progressive prostate cancers in paraffin-embedded tissues. CD44, an adhesion molecule that has been useful for the prediction of prognosis in some other cancers, has not been described in prostate cancer. The expression of CD44 was investigated with the monoclonal antibody GKW.A3 in prostate cancer in formalin-fixed, paraffin-embedded tissue sections of (1) whole prostates from 50 patients with 74 prostate cancers; and (2) lymph node metastases from 14 patients. Sixty percent of primary prostate cancers expressed CD44 moderately to strongly. No metastases expressed CD44 moderately to strongly; only 14% of metastases expressed even low levels of immunohistochemically detectable CD44. There is a difference between primary and metastatic prostate cancer (P <.0006) in the expression of CD44 and an inverse correlation (P <.05) between histological differentiation (Gleason grade) and the expression of CD44. The magnitude of the differential expression of CD44 in primary and metastatic prostate cancers suggests it should be investigated as an indicator of prognosis in a large prospective study.

[A randomized clinical trial for the evaluation of head and neck squamous cell carcinoma treating with traditional Chinese medicine]

This paper described the research design,research process and statistical analysis of randomized clinical trial by treatment with traditional Chinese medicine in patients with squamous cell carcinoma of the head and neck.At first we found there was no significant difference between treating group and contral group(P>0.05) using log-rank test on Kaplan-Meier survival curves. With further multivariate analysis Cox model and after adjusting for sex,age,legth of taking the assigned medication,grade of tumor differentiation and using of chemotherapy,the rate of tumor-related death for control group was significantly higher than that for treating group :hazards ratio estimate was 1.939(95% confidence interval 1.008-3.729,(P<0.05).The length of taking Chinese medicine was one of the most important prognostic factors(P<0.001).The results suggest that the prescribed medication contributed to the improved survival,and it was an independent prognostic factor.