Synthesis and biological evaluation of a series of new cyclohexenyl nucleosides

A series of cyclohexenyl nucleosides (1-8) were successfully prepared with moderate yield and their cytotoxicity and antiviral activity were investigated. Among the eight new compounds, only the diaminopurine analogue 8 showed pronounced activity against HSV-1, HSV-2.

Conserving vedalia beetle, Rodolia cardinalis (Mulsant) (Coleoptera: Coccinellidae), in citrus: a continuing challenge as new insecticides gain registration

The effects of insecticides used for California citrus pest management were evaluated using larval and adult stages of vedalia beetle, Rodolia cardinalis (Mulsant). This predatory beetle is essential for control of cottony cushion scale Icerya purchasi (Williston) (Homoptera: Margarodidae) in San Joaquin Valley citrus. When adult beetles were exposed to treated citrus leaves, adult survival was significantly reduced by the foliar neonicotinoid imidacloprid and the pyrethroid cyfluthrin. Progeny production was significantly reduced by imidacloprid, cyfluthrin, fenpropathrin, and buprofezin. Buprofezin, pyriproxifen, and foliar imidacloprid also significantly reduced successful development of larvae into the adult stage. When vedalia stages were fed insecticide-treated cottony cushion scale reared on Pittosporum tobira (Thunb.) Ait, toxic effects were more severe than contact toxicity alone. Adult beetle survival was most profoundly reduced by the pyrethroids and to a lesser extent the foliar neonicotinoids acetamiprid and imidacloprid. Progeny production and larval development to adulthood were reduced by all insecticides but were most severely affected by pyriproxifen and the pyrethroids. Systemically applied neonicotinoids were toxic to vedalia larvae feeding on cottony cushion scale that had ingested these insecticides. These data demonstrate that IGRs, neonicotinoid insecticides, and pyrethroid insecticides have a significant, negative impact on vedalia beetles. Depending on the rate of insecticide used, the number and timing of applications, and the level of coverage of the tree, disruption of vedalia can be minimized. However, the situation is made difficult when pests such as citrus thrips Scirtothrips citri (Moulton) (Thysanoptera: Thripidae), forktailed bush katydid Scuddaria furcata Brunner von Wattenwyl (Orthoptera: Tettigoiniidae), or glassy-winged sharpshooter Homalodisca coagulata Say (Homoptera: Cicadellidae) require these pesticide treatments during periods of vedalia beetle activity.

[Effect of tumor necrosis factor-alpha on differentiation of mesencephalic neural stem cells and proliferation of oligodendrocytes in the rat]

To observe the influence of tumor necrosis factor-alpha (TNF-alpha) on differentiation of rat mesencephalic neural stem cells (NSCs), the numbers of neurons, astrocytes and oligodendrocytes generated from NSCs were analyzed after differentiation for 3 days by using immunocytochemistry technique. The results show that: (1) TNF-alpha enhanced the proportions of neurons and oligodendrocytes in progeny of NSCs; and (2) TNF-alpha induced the proliferation of oligodendrocytes derived from NSCs, but the proliferation of astrocytes was not influenced by TNF-alpha. We conclude that the TNF-alpha could influence the application of NSCs.

The effect of bone marrow stromal cells on neuronal differentiation of mesencephalic neural stem cells in Sprague-Dawley rats

There are numerous parallels between the heamatolymphopoietic and nervous systems in terms of the mechanisms regulating their development. We proposed that neural stem cells (NSCs) may respond to the microenvironmental signals provided by bone marrow stromal cells (BMSCs) which regulate the differentiation and maturation of hematolymphopoietic stem cells. First, we isolated and proliferated BMSCs from the femur and tibia, and NSCs from the midbrain of Sprague-Dawley (SD) rats, and then investigated the effects of BMSCs on the differentiation of NSCs into neurons, astrocytes and oligodendrocytes by directly plating neurospheres on BMSC monolayers in serum-free conditions. The results confirmed that BMSCs induced NSCs to differentiate selectively into neurons. The percentage of neurons significantly increased in 7 days in vitro co-cultures of NSCs and BMSCs as compared to NSCs cultures alone. When the duration of the cultures was extended to 12 days in vitro, BMSCs enhanced the survival of neurons derived from these NSCs; our investigation then focused on the underlying mechanism for this effect of BMSCs. NSCs were cultured with BMSC conditioned-medium and co-cultured with membrane fragments of live BMSCs or paraformaldehyde fixed BMSCs, the inducing activity of BMSCs was solely detectable in BMSC conditioned-medium, indicating that soluble factors secreted by BMSCs were responsible for its effect on the neuronal differentiation of NSCs. Therefore, BMSCs may provide a powerful tool for therapeutic neurological applications.

Synthesis and antiviral activity of a series of new cyclohexenyl nucleosides

A series of new cyclohexenyl nucleosides is synthesized by coupling the heterocyclic bases with a protected cyclohexenyl precursor under Mitsunobu conditions. The compounds were evaluated for their antiviral and cytostatic activity. Pronounced activity against herpes simplex virus type 1 and type 2 was observed for the 2,6-diaminopurine analogue.

Discovery of two novel functional genes from differentiation of neural stem cells in the striatum of the fetal rat

Neural stem cells (NSC) are capable of differentiating into neurons and glia. However, the molecular mechanisms regulating NSC differentiation are not well understood. We have used the differential display polymerase chain reaction to analyze the differentially expressed genes of NSC from Sprague-Dawley rat striatum. Twelve differentially expressed sequence tags (ESTs) have been discovered and two of them, SHD10 and SHD11, were confirmed to be positive by reverse Northern blot techniques. Sequencing analyses showed that SHD10 shared a 94% (547/581) homology with mouse EST BI687817, but its biological function has not been reported. SHD11 shared a 91% (512/562) homology with mouse EST BG172336. It encodes an open reading frame containing 117 amino acids. Analysis of protein sequence indicated that it has a 98% homology with dendritic cell factor (gi18203393). Our research primarily discovered that these two genes are associated with differentiation of NSC. How they function in the process of differentiation needs further study.

Microarray analysis of neural stem cell differentiation in the striatum of the fetal rat

1. Gene expression profiles in neural stem cell differentiation in vitro were determined by cDNA microarray analysis. 2. Total RNA was extracted and reverse transcripted into cDNA from differentiated and undifferentiated neural stem cells. The 33P labeled cDNA was hybridized with a cDNA microarray consisting of 14,000 human genes. 3. The results showed that a total of 1406 genes were differentially expressed, of which 148 genes exhibited more than twofold differences. Some genes were obviously activated while others were strongly repressed. These changes in gene expression suggest that differentiation is regulated by different genes at different expressional levels. By biological classification, the differentially expressed genes were divided into four functional categories: molecular function, biological process, cellular component, and new functional genes or ESTs. 4. These findings will be a valuable contribution for gene expression profiling and elucidation of neural stem cell differentiation mechanisms.

Detection of genomic alterations in human endometrial cancer by two-dimensional gel electrophoresis

OBJECTIVE

The purpose of this study was to detect genomic alterations in human endometrial cancer by two-dimensional gel electrophoresis.

STUDY DESIGN

With use of a newly developed two-dimensional gel electrophoresis assay, we scanned 19 high-risk DNA fragments for alterations in human endometrial hyperplasias and adenocarcinomas. This method includes cleaving of high-molecular-weight DNA, radioactive labeling, and separating DNA fragments by two-dimensional gel electrophoresis. By comparing the two-dimensional gel electrophoresis profile (spots) of neoplastic with normal endometrium, genetic alterations such as amplification, allelic loss, and hypermethylation or hypomethylation can be detected.

RESULTS

Seven of 8 human endometrial adenocarcinoma (88%) and 1 of 2 hyperplasias (50%) revealed changes in spot density. The number of spots changed per specimen was 4. The median percentage of specimens with changes in an individual spot was 30%. Eleven spots had a reduction or loss of spot density, and 8 spots had an increase in spot density.

CONCLUSION

By use of a novel two-dimensional gel electrophoresis assay, we identified genetic alterations in 50% of hyperplasias and 88% of endometrial adenocarcinomas.

Observation of the decay K- --> pi(-)mu(+)mu(-) and measurements of the branching ratios for K+/- --> pi(+/-)mu(+)mu(-)

Using data collected with the HyperCP (E871) spectrometer during the 1997 fixed-target run at Fermilab, we report the first observation of the decay K--->pi(-)mu(+)mu(-) and new measurements of the branching ratios for K+/--->pi(+/-)mu(+)mu(-). By combining the branching ratios for the decays K+-->pi(+)mu(+)mu(-) and K--->pi(-)mu(+)mu(-), we measure Gamma(K+/--->pi(+/-)mu(+)mu(-))/Gamma(K+/--->all) = (9.8+/-1.0+/-0.5)x10(-8). The CP asymmetry between the rates of the two decay modes is [Gamma(K+-->pi(+)mu(+)mu(-))-Gamma(K--->pi(-)mu(+)mu(-))]/[Gamma(K+-->pi(+)mu(+)mu(-))+Gamma(K--->pi(-)mu(+)mu(-))] = -0.02+/-0.11+/-0.04.

Mutagenesis of the regulatory domain of phenylalanine hydroxylase

The regulatory domain of phenylalanine hydroxylase (PAH, EC ) consists of more than 100 amino acids at the N terminus, the removal of which significantly activates the enzyme. To study the regulatory properties controlled by the N terminus, a series of truncations and site-specific mutations were made in this region of rat PAH. These enzymes were expressed highly in Escherichia coli and purified through a pterin-conjugated Sepharose affinity column. The removal of the first 26 amino acids of the N terminus increased the activity by about 20-fold, but removal of the first 15 amino acids increased the activity by only 2-fold. Replacing serine-29 of rat PAH with cysteine from the same site of human PAH increased the activity by more than 4-fold. Mutation of serine to other amino acids with varying side chains: alanine, methionine, leucine, aspartic acid, asparagine, and arginine also resulted in significant activation, indicating a serine-specific inhibitory effect. But these site-specific mutants showed 30--40% lower activity when assayed with 6-methyl-5,6,7,8-tetrahydropterin. Stimulation of hydroxylase activity by preincubation of the enzyme with phenylalanine was inversely proportional to the activation state of all these mutants. Combined with recent crystal structures of PAH [Kobe, B. et al. (1999) Nat. Struct. Biol. 6, 442-448; and Erlandsen, H., Bjorgo, E., Flatmark, T. & Stevens, R. C. (2000) Biochemistry 39, 2208-2217], these data suggest that residues 16-26 have a controlling regulatory effect on the activity by interaction with the dihydroxypropyl side chain of (6R)-5,6,7,8-tetrahydrobiopterin. The serine/cysteine switch explains the difference in regulatory properties between human and rat PAH. The N terminus as a whole is important for maintaining rat PAH in an optimum catalytic conformation.

Detection of genetic alterations in mouse lung adenocarcinomas by two-dimensional gel electrophoresis

DNA from 14 mouse lung adenocarcinomas and 7 normal lungs were examined by 2-dimensional gel electrophoresis (2-DGE) for genetic alterations. 2-DGE profiles from tumor samples were compared with those profiles from normal lung tissues through a computer-assisted color overlay system. Compared to the profiles in normal lung DNA, 6 spots were amplified and 16 spots were partially reduced in their intensity in tumors. Two spots were detectable only in tumor tissues. These altered spots indicate genetic changes in mouse lung tumor development. The identification of these genetic alterations is probably important in understanding mouse lung carcinogenesis.

[Expression of proteolytic enzymes of metastatic tumor cells and the effects of some influencing factors]

OBJECTIVE

To elucidate the types of proteolytic enzymes the dendritic cell sarcoma (DCS) cell expressed in vitro and the effects of modulating factors.

METHODS

The proteolytic spots of DCS cells were examined, with ten different proteinase inhibitors, various antibodies and matrix.

RESULTS

Aprotinin, EDTA-Na2 and pepstatin could inhibit the proteolysis of DCS cells respectively. Anti-ubiquitin antibody and anti-DCS antibody (1:200-1:100) showed no obvious inhibitory effects. DCS cells spread out fairly well but with no proteolysis.

CONCLUSIONS

Under the conditions of our experiments the DCS cells had serine proteinase, metalloproteinase and aspartate proteinase activities. Antiubiquitin antibodies and anti-DCS antibodies showed no obvious influence on the proteolysis of DCS cells. DCS cells displayed different proteolysis status on different matrix.

[The effects of 6A8 cDNA transfection on biological behavior of tumor cells]

OBJECTIVE

To investigate the effects of antisense 6A8 cDNA on the malignant behavior of tumor.

METHODS

Highly metastatic clonal variant CNE-2L2 from nasopharygeal carcinoma cell line(CNE-2Z) was transfected with antisense 6A8 cDNA or mock plasmid. Their adhesion, locomotion, proteolytic ability, in vitro invasion, in vivo growth and metastasis were comparatively studied with the wild CNE-2L2 cells.

RESULTS

Antisense 6A8 cDNA transfected CNE-2L2 showed less adhesion to FN and LN, weakened locomotive ability and proteolytic ability, retarded in vivo growth and much less metastasis.

CONCLUSION

Transfection of antisense 6A8 cDNA obviously decreased the malignant behavior of tumor cells.

Function-structure studies and identification of three enzyme domains involved in the catalytic activity in rat hepatic squalene synthase

Rat hepatic squalene synthase (RSS, EC 2.5.1.21) contains three conserved sections, A, B, and C, that were proposed to be involved in catalysis (McKenzie, T. L., Jiang, G., Straubhaar, J. R., Conrad, D., and Shechter, I. (1992) J. Biol. Chem. 267, 21368-21374). Here we use the high expression vector pTrxRSS and site-directed mutagenesis to determine the specific residues in these sections that are essential for the two reactions catalyzed by RSS. Section C mutants F288Y, F288L, F286Y, F286W, F286L, Q293N, and Q283E accumulate presqualene diphosphate (PSPP) from trans-farnesyl diphosphate (FPP) with reduced production of squalene. F288L, which retains approximately 50% first step activity, displays only residual activity (0.2%) in the production of squalene from either FPP or PSPP. Substitution of either Phe288 or Phe286 with charged residues completely abolishes the enzyme activity. Thus, F288W, F288D, F288R, F286D, and F286R cannot produce squalene from either FPP or PSPP. All single residue mutants in Section A, except Tyr171, retain most of the RSS activity, with no detectable accumulation of PSPP in an assay mixture complete with NADPH. Y171F, Y171S, and Y171W are all inactive. Section B, which binds the diphosphate moieties of the allylic diphosphate subtrates, contains four negatively charged residues: Glu222, Glu226, Asp219, and Asp223. The two Glu residues can be replaced with neutral or with positively charged residues without signficantly affecting enzyme activity. However, replacement of either Asp residues with Asn eliminates all but a residual level of activity, and substitution with Glu abolishes all activity. These results indicate that 1) Section C, in particular Phe288, may be involved in the second step of catalysis, 2) Tyr171 of Section A is essential for catalysis, most likely for the first reaction, 3) the two Asp residues in Section B are essential for the activity and most likely bind the substrate via magnesium salt bridges. Based on these results, a mechanism for the first reaction is proposed.

[Peripheral artery blood flow measurements using pulsed Doppler and electromagnetic flowmetry in dogs: a comparative study]

To investigate the accuracy of blood flow parameters in peripheral artery by Doppler ultrasound, the intermal diameter(D), peak velocity(Vp), mean velocity (Vm) and flow volume (Q) of dog's femoral artery were measured by using either a pulsed Doppler (PD) system or electromagnetic flowmeters(EMFM). The results showed that the D measured by B-mode ultrasound values significantly smaller than that by callipers but it correlated very well with the D by callipers. When the values of Vp, Vm and Q measured by pulsed Doppler and EMFM were compared, the Vp had the most highly significant correlation between the data obtained by the two techniques (r: 0.91, 0.79, 0.83 respectively). When Vp, Vm and Q were measured by angle correction of PD, the correlations between the data determined by the two techniques were still significant(r: 0.88, 0.82, 0.78).

Characterization of a novel microsomal fatty acid synthetase (FAS) compared to a cytosolic FAS in the housefly, Musca domestica

A novel membrane-bound fatty acid synthetase (FAS) associated with the microsomal fraction from the housefly, Musca domestica, was solubilized and purified to homogeneity. The microsomal FAS was solubilized by 0.75 M KCl in phosphate buffer and was purified to homogeneity by the sequential use of ammonium sulfate precipitation followed by Sepharose CL-6B, DEAE Sephacel and Red Agarose (dye ligand affinity) chromatography. The specific activity of the microsomal FAS was increased 1,440-fold to 6,522 U/mg during purification. The cytosolic FAS from the housefly was also purified by similar methods and the specific activity increased 183-fold to 7,533 U/mg. The relative molecular mass of the microsomal and cytosolic FAS are 419 +/- 22 kDa and 405 +/- 18 kDa, respectively, for the dimers as determined by gel permeation chromatography. The microsomal and the cytosolic FAS yield different tryptic digestion maps and have slightly different amino acid compositions, which demonstrate structural differences between the two FASs. In addition, there are differences between the two FASs in their kinetic characteristics and their ability to incorporate methylmalonylCoA into the growing fatty acyl chain.

Detection of genomic alterations in human cervical cancer by two-dimensional gel electrophoresis

Two-dimensional gel electrophoresis was used to comprehensively scan the whole genome of 6 cervical intraepithelial neoplasia (CIN) lesions, 7 cervical squamous cell carcinomas, 1 cervical adenosquamous cell carcinoma, and 2 cervical adenocarcinomas for multiple genetic alterations, such as DNA amplification, chromosome deletion, loss of heterozygosity, and chromosome translocation, as compared with the paired normal tissues. DNA spot analysis of the genomic 2-dimensional gels was performed by a computer color overlay system and by spot recognition software allowing for objective spot comparison and quantitation. Nine spots were found to be amplified in the cervical carcinomas while two amplified spots were detected in the CIN III lesions. Fourteen DNA spots were either reduced in their intensity or absent in cervical carcinomas as compared to their normal paired tissues. Reduction of intensity in 6 spots was observed in the 5 CIN III lesions. These genetic alterations may represent changes in cancer genes that are associated with human cervical carcinogenesis. Further characterization of these alterations may be significant to the understanding of cervical tumorigenesis and to the development of biomarkers for clinical trials in cancer chemoprevention.

Regulation of enzymatic activity involved in sex pheromone production in the housefly, Musca domestica

Ovarian produced ecdysteroids regulate sex pheromone production in the female housefly, inducing the synthesis of (Z)-9-tricosene (Z9-23:Hy), cis-9,10-epoxytricosane, (Z)-14-tricosen-10-one and methylalkanes. Experiments were performed to gain a detailed understanding of the processes affected by 20-hydroxyecdysone (20-HE) that result in sex pheromone production as the female becomes reproductively mature. A novel microsomal fatty acid synthetase (FAS) is present in the epidermal tissue and plays a role in producing the methyl-branched fatty acid precursors to the methylalkanes. This FAS is released from the microsomes in the presence of 3 M KCl. A major enzyme activity influenced by 20-HE is the fatty acyl-CoA elongation system. A shift in the chain length specificity of the products of the elongation system causes the change in the chain lengths of the alkenes produced to switch from C27 and longer in the previtellogenic female to C23 in the mature female. Data is presented indicating that it is the condensation activity of the elongation system that is affected. Z9-23:Hy arises from a 24 carbon acyl group which is reduced to an aldehyde, and then converted to the hydrocarbon. Data is presented demonstrating that it is the fatty acyl-CoA derivative and not the free fatty acid that is the substrate. There does not appear to be a chain length specificity which regulates the conversion of fatty acyl-CoAs to hydrocarbons as both 24 and 28 carbon fatty acyl-CoAs are converted to hydrocarbon by both males and females of all ages.

Spectrophotometer for measuring spectral reflectance and transmittance

The development of a computer-controlled spectrophotometer that enables measurement of spectral transmittance, reflectance, and optical loss of thin-film specimens is discussed. We also describe the design and testing procedure of the spectrophotometer, incorporating test sample performance data. In the visible region the overall photometric accuracy is verified to be 0.1% and 0.2% for transmittance and reflectance, respectively. The wavelength scale is accurate to within 0.5 nm with a reproducibility of 0.1 nm.

[Chemosensitivity testing of fresh human gastrointestinal cancers using AgNOR assay]

The argyrophilic staining of nucleolar onganizer region (AgNOR), a simple colorimetric test, has been adapted for chemosensitivity testing of human gastric and colorectal cancers. Seven different chemotherapeutic agents were tested. The drug sensitivity was measured and compared according to the decrease rate of AgNOR granules between control tumor cells and tumor cells treated with antitumor drugs. Only 3 of 10 cases of advanced gastric carcinoma were sensitive to one antitumor agent. Most colorectal carcinoma cases (18/20) were sensitive to at least one antitumor agent. The sensitive sequence of antitumor agents we have had in this study was relative to clinic. The method and characteristics of AgNOR assay as a chemosensitivity test was introduced. It's value is being observed.

Simulation of thin-film growth

A two-dimensional simulation model of thin-film deposition, which involves the effect of the incident kinetic energy of atoms and the mobility of the substrate temperature, is developed. Lennard-Jones potential and nuclear scattering are used to characterize the atom-atom interaction. The effect of substrate temperature on the relaxation of depositing particles is also considered. Some simulation results are presented and discussed in detail.

Damage thresholds of (ZrO(2)-Y(2)O(3)/SiO(2) reflectors used for XeCl lasers

An excimer laser reflector at the wavelength of 308 nm (XeCl) consisting of materials of ZrO(2)-Y(2)O(3) and SiO(2) is prepared. The reflectance reaches ~99.5% and the laser-induced damage threshold is raised to ~8.5 J/cm(2). The ZrO(2)-Y(2)O(3) mixture is proven to be a film material with a high laser damage resistance.

[DNA content measured by flow cytometry in primary hepatic carcinoma and its clinical significance]

Twenty-two samples of resected primary hepatic carcinoma (PHC) and liver tissues of resective margin were studied by flow cytometric single-variable analysis combined with clinical data. The results showed that the DNA content measured by flow cytometry was a relatively independent factor indicating biological behavior in PHC. The DNA content was increased and the great majority of PHC cells were of aneuploid cells (90.0%). DNA histograms varied and the occurrence rate of multi-aneuploid was 35%. The DNA content distributed widely, indicating that PHC cells were heterogeneous. The occurrence rate of aneuploid was 61.9% in histologically negative hepatic tissues of resective margin, and it was not correlated with categories of hepatic resection. The existence of aneuploid cells in liver tissues of resective margin is thus considered an important factor for the recurrence of PHC. We suggest that surgical treatment is inadequate and adjuvant therapy is required.