Correlating gene expression with chemical scaffolds of cytotoxic agents: ellipticines as substrates and inhibitors of MDR1

To facilitate a systematic study of chemoresistance across diverse classes of anticancer drug candidates, we performed correlation analyses between cytotoxic drug potency and gene expression in 60 tumor cell lines (NCI-60; NCI-National Cancer Institute). Ellipticine analogs displayed a range of correlation coefficients (r) with MDR1 (ABCB1, encoding multidrug resistance (MDR) protein MDR1 or P-glycoprotein). To determine MDR1 interactions of five ellipticines with diverse MDR1-r values, we employed MDR1-transport and cytotoxicity assays, using MDR1 inhibitors and siRNA-mediated MDR1 downregulation, in MDR1-overexpressing cells. Ellipticines with negative correlations-indicative of MDR1-mediated resistance-were shown to be MDR1 substrates, whereas those with neutral or positive correlations served as MDR1 inhibitors, which escape MDR1-mediated chemoresistance. Correlation with additional genes in the NCI-60 confirmed topoisomerases as ellipticine targets, but suggested distinct mechanisms of action and chemoresistance among them, providing a guide for selecting optimal drug candidates.

Mechanisms of strontium and uranium removal from high-level radioactive waste simulant solutions by the sorbent monosodium titanate

High-level waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U.S. Department of Energy's Environmental Management Program. Current HLW treatment processes at the Savannah River Site (Aiken, SC) include the use of monosodium titanate (MST, with a similar stoichiometry to NaTi2O5 x xH2O) to concentrate strontium (Sr) and actinides. The high affinity of MST for Sr and actinides in HLW solutions rich in Na+ is poorly understood. Mechanistic information about the nature of radionuclide uptake will provide insight about MST treatment reliability. Our study characterized the morphology of MST and the chemistry of sorbed Sr2+ and uranium [U(VI)] as uranyl ion, UO2(2+), on MST, which were added (individually) from stock solutions of Sr and 238U(VI) with spectroscopic and transmission electron microscopic techniques. The local structure of sorbed U varied with loading, but the local structure of Sr did not vary with loading. Sorbed Sr exhibited specific adsorption as partially hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account forthe difficulties associated with predicting Sr and U loading and removal kinetics using MST.

Differential targets of CpG island hypermethylation in primary and metastatic head and neck squamous cell carcinoma (HNSCC)

Head and neck squamous cell carcinomas (HNSCC) often metastasise to the cervical lymph nodes. It is known for HNSCC as well as other cancers that progression from normal tissue to primary tumour and finally to metastatic tumour is characterised by an accumulation of genetic mutations. DNA methylation, an epigenetic modification, can result in loss of gene function in cancer, similar to genetic mutations such as deletions and point mutations. We have investigated the DNA methylation phenotypes of both primary HNSCC and metastatic tumours from 13 patients using restriction landmark genomic scanning (RLGS). With this technique, we were able to assess the methylation status of an average of nearly 1300 CpG islands for each tumour. We observed that the number of CpG islands hypermethylated in metastatic tumours is significantly greater than what is found in the primary tumours overall, but not in every patient. Interestingly, the data also clearly show that many loci methylated in a patient's primary tumour are no longer methylated in the metastatic tumour of the same patient. Thus, even though metastatic HNSCC methylate a greater proportion of CpG islands than do the primary tumours, they do so at different subsets of loci. These data show an unanticipated variability in the methylation state of loci in primary and metastatic HNSCCs within the same patient. We discuss two possible explanations for how different epigenetic events might arise between the primary tumour and the metastatic tumour of a person.

Cutting edge: Secondary lymphoid organs are essential for maintaining the CD4, but not CD8, naive T cell pool

Despite declining thymic output with age, the peripheral naive T cell pool of an adult animal remains remarkably stable. Therefore, a central question in immunology is how the naive T cell pool is maintained. Here we show that the maintenance of the naive CD4, but not CD8, T cell population in the thymectomized adult mouse is dependent on the presence of secondary lymphoid tissues. This finding is explained by the inability of naive CD4 T cells to sustain normal levels of the survival molecule Bcl-2 or to undergo homeostatic proliferation in the absence of secondary lymphoid organs. Thus, naive CD4 T cells must traffic through secondary lymphoid organs to maintain a stable CD4 pool while naive CD8 T cells encounter their survival and proliferation signals outside the organized structures of secondary lymphoid tissues.

[Expression of the artificial cecropin CMIV-like gene of Chinese silkworm Bombyx mori in Laphygma exigua larvae]

The synthesized CMIV-like Gene was linked with the signal peptide gene of nature silkworm antibacterial peptide and was inserted into baculovirus expression vector pFastBac 1, construcing a recombinant transposing vector. The vector was transformed into DH10Bac competent E. coli cells. The recombinant Bacmid was obtained. The recombinant Bacmid was transfected into sf21 cells to get the recombinant virus. Laphygma exigua larvae were infected with the recombinant virus to express the antibacterial peptide. The hemolymph were tested to have antibacterial activity. The active antibacterial peptide was purified by acid polyacrylamide electrophoresis. The specific expression of mRNA of CMIV-like Gene was tested using Northern blotting.

Increased expression of unmethylated CDKN2D by 5-aza-2'-deoxycytidine in human lung cancer cells

DNA hypermethylation of CpG islands in the promoter region of genes is associated with transcriptional silencing. Treatment with hypo-methylating agents can lead to expression of these silenced genes. However, whether inhibition of DNA methylation influences the expression of unmethylated genes has not been extensively studied. We analysed the methylation status of CDKN2A and CDKN2D in human lung cancer cell lines and demonstrated that the CDKN2A CpG island is methylated, whereas CDKN2D is unmethylated. Treatment of cells with 5-aza-2'-deoxycytidine (5-Aza-CdR), an inhibitor of DNA methyltransferase 1, induced a dose and duration dependent increased expression of both p16(INK4a) and p19(INK4d), the products of CDKN2A and CDKN2D, respectively. These data indicate that global DNA demethylation not only influences the expression of methylated genes but also of unmethylated genes. Histone acetylation is linked to methylation induced transcriptional silencing. Depsipeptide, an inhibitor of histone deacetylase, acts synergistically with 5-Aza-CdR in inducing expression of p16(INK4a) and p19(INK4d). However, when cells were treated with higher concentrations of 5-Aza-CdR and depsipeptide, p16(INK4a) expression was decreased together with significant suppression of cell growth. Interestingly, p19(INK4d) expression was enhanced even more by the higher concentrations of 5-Aza-CdR and depsipeptide. Our data suggest that p19(INK4d) plays a distinct role from other INK4 family members in response to the cytotoxicity induced by inhibition of DNA methylation and histone deacetylation.

[Yu Jinghe's Chronicle]

The life and origin of medical learning from family of Yu Jinghe, renowned doctor of the Qing Dynasty, are described here in the form of chronicle. He was born in Yixing, Jiangsu. His parent died when he was a boy and he joined the Taiping Army for 5 years with difficult experiences. Later, he moved to Menghe and learned pharmacology from his elder brother. His works include Yu's Annotation on Shanghanlun Yi, Collection of Case Records on External Diseases, Collection After Practising Hour etc. Moreover, Yu's descendents and his close relationship with other modern celebrated doctors such as Ding Ganren and his son Ding Zhongying, and Yun Tieqiao are also mentioned.

[Defective expression of B7.2 in B cell chronic lymphocytic leukemia B cells]

OBJECTIVE

To investigate the expression of B7.1 and B7.2 molecules in peripheral B cells of patients with chronic B cell lymphocytic leukemia (BCLL) and to study the relationship between B7.1 and B7.2 expression and pathogenic mechanism of BCLL.

METHODS

Peripheral blood mononuclear cells (PBMC) were separated by Ficoll-Hypaque lymphocytes separation medium from 25 normal persons (normal control group) and 23 BCLL patients (BCLL group) which were further divided into two groups, phase 0-II group and phase III-IV group. Flow cytometry (FCM) was used to analyze the B7.1 and B7.2 expression in peripheral B cells after the mononuclear cells had been cultured for 24 hours in vitro.

RESULTS

The B7.2 expression in B cells of BCLL patients was significantly lower than that in normal control group (P < 0.05). No statistically significant difference was found in the B7.1 expression and co-expression of B7.1 and B7.2 between the BCLL group and normal control group. The average B7.2 expression rates in patients of phase 0-II group and phase III-IV group were 25% +/- 17% and 17% +/- 8% respectively without statistically significant difference.

CONCLUSION

The B7.2 expression in B cell of patients with BCLL is defective, which may be one of the pathogenic mechanisms of chronic BCLL and a major cause why the body fails to clear the BCLL cells via immunological means.

Expression of a Mycobacterium tuberculosis arabinomannan antigen in vitro and in vivo

The outermost layer of Mycobacterium tuberculosis contains two major polysaccharides, arabinomannan (AM) and glucan (GC). We studied the in vitro and in vivo expression of an M. tuberculosis AM antigen using monoclonal antibody (MAb) 9d8 (2a), an isotype-switched variant of the immunoglobulin G3 (IgG3) MAb 9d8. MAb 9d8 had been previously shown to bind M. tuberculosis AM and the M. tuberculosis surface. Our in vitro experiments showed that MAb 9d8(2a) bound strongly to whole-cell M. tuberculosis Erdman but not to the CDC 1551 strain grown in medium for an extended period. However, AM antigen was detected in the culture supernatant of both strains, and its concentration increased in a time-dependent manner. The detection of AM antigen from both strains was decreased in the presence of Tween 80. In mice infected with M. tuberculosis Erdman, AM antigen accumulated in organ homogenates concomitant to an increase in bacterial organ burden and an increase in IgG and IgM titer to AM. These results (i) indicate that the surface expression of AM during in vitro growth changes with culture age, is strain dependent, and is affected by the presence of Tween 80 in the culture media; (ii) show that AM is produced by bacteria growth in vivo; and (iii) demonstrate that the amount of in vivo-detected AM can be dependent on the number of bacteria in the infected organ.

Aberrant promoter methylation of previously unidentified target genes is a common abnormality in medulloblastomas--implications for tumor biology and potential clinical utility

Medulloblastomas exhibit an array of diverse cytogenetic abnormalities. To evaluate the significance of epigenetic rather than genetic lesions in medulloblastomas and other primitive neuroectodermal tumors (PNETs) of the childhood CNS we performed a systematic analysis of gene specific and global methylation. Methylation-specific PCR detected no methylation for p15(INK4B), von Hippel Lindau and TP53 and only limited methylation for E-Cadherin and p16(INK4A) in tumors. The cell lines Daoy and MHH-PNET-5 in which the p16(INK4A) promoter was methylated did not express the gene, but demonstrated abnormalities by SSCP. Immunohistochemistry for p16 was negative in all examined normal cerebella and medulloblastomas. Using the technique of Restriction Landmark Genomic Scanning we detected methylation affecting up to 1% of all CpG islands in primary MB/PNETs and 6% in MB cell lines. Methylation patterns differed between medulloblastomas and PNETs. Examination of several methylated sequences revealed homologies to known genes and expressed sequences. Analysis of survival data identified seven of 30 hypermethylated sequences significantly correlating with poor prognosis. We suggest that DNA hypermethylation has an outstanding potential for the identification of novel tumor suppressors as well as diagnostic and therapeutic targets in MBs and other PNETs of the CNS.

Deletion of the Src homology 3 domain and C-terminal proline-rich sequences in Bcr-Abl prevents Abl interactor 2 degradation and spontaneous cell migration and impairs leukemogenesis

The hematopoietic cells from patients with Bcr-Abl-positive chronic myelogenous leukemia exhibit multiple abnormalities of cytoskeletal function. The molecular events leading to these abnormalities are not fully understood. Previously we showed that Bcr-Abl elicits ubiquitin-dependent degradation of Abl interactor proteins. Because recent studies have suggested a role of Abl interactor proteins in the pathway that regulates cytoskeletal function, we investigated whether mutations in Bcr-Abl that interfere with the signaling to Abl interactor proteins affect its leukemogenic activity. We report here that the Src homology 3 domain and C-terminal proline-rich sequences of Bcr-Abl are required for its binding to Abl interactor 2 as well as for the induction of Abl interactor 2 degradation. Although the deletion of these regions did not affect the ability of the mutant Bcr-Abl to transform hematopoietic cells to growth factor independence, it abrogated its ability to stimulate spontaneous cell migration on fibronectin-coated surfaces. Furthermore, the mutant Bcr-Abl, defective in binding to Abl interactor 2 and inducing its degradation, failed to induce chronic myelogenous leukemia-like disease in mouse. These results are consistent with a role of Abl interactor proteins in the regulation of cytoskeletal function as well as in the pathogenesis of Bcr-Abl-induced leukemogenesis.

[Hypermethylation as a potential prognostic factor and a clue to a better understanding of the molecular pathogenesis of medulloblastoma--results of a genomewide methylation scan]

BACKGROUND

The molecular mechanisms controlling initiation and progression of medulloblastomas are largely unclear. Changes in DNA methylation of promoter regions have been shown to disturb the expression of growth regulatory genes.

PATIENTS AND METHODS

We evaluated DNA methylation patterns in 17 medulloblastomas, 5 stPNETs and 5 medulloblastoma cell lines using Restriction Landmark Genomic Scanning (RLGS), a method displaying up to 2.000 potential gene loci in a single gene. To test whether previously characterized tumor suppressor genes are affected by hypermethylation we performed MS-PCR for p15INK4B, p16INK4A, VHL, TP53 and E-cadherin.

RESULTS

The analysis of RLGS profiles from tumors revealed an abundance of hypermethylation in primary tumors and cell lines. Extrapolated to the human genome with its approximately 36,000 genes a total of 420 loci become hypermethylated in the tumor genomes. The previously characterized medulloblastoma breakpoint cluster in 17p11.2 appears to be a hotspot for aberrant methylation. Cox regression analysis of survival data identified seven CpG islands for which hypermethylation is suggestive of a poor prognosis. MS-PCR analysis of known genes demonstrated hypermethylation of p16INK4A in a limited number of tumors. The pattern of DNA hypermethylation was similar in medulloblastomas and stPNETs. However, some CpG islands were shown to be specific for a tumor type, while others were shared targets.

CONCLUSIONS

Hypermethylation is a common abnormality in primary medulloblastomas and supratentorial PNETs. Several hundreds of CpG islands are potential targets for methylation in medulloblastomas including the breakpoint cluster in 17p11.2. The methylation status of certain gene sequences appears to be associated with the clinical outcome. Promoter hypermethylation has an outstanding potential as a marker for the identification of novel tumor suppressors as well as diagnostic and therapeutic targets in medulloblastomas.

Excessive CpG island hypermethylation in cancer cell lines versus primary human malignancies

Cancer cell lines are widely used in many types of cancer research, including studies aimed at understanding DNA hypermethylation of gene promoters in cancer. Hypermethylation of promoters is capable of repressing the expression of tumor suppressor genes and may play a role in the development and/or progression of cancer. Although both primary malignancies and cancer cell lines exhibit this epigenetic phenomenon, there has been no direct comparison between them. In order to address this question, we have utilized restriction landmark genomic scanning to measure the hypermethylation phenotypes of cancer cell lines and compared these data with the same analysis performed on primary malignancies. In all cases, cancer cell lines exhibit significantly higher levels of CpG island hypermethylation than the primary malignancies they represent. Colon cancer cell lines are most similar to their respective tumors, with only a 5-fold increase in hypermethylation, while head and neck squamous cell carcinoma cell lines show a 93-fold increase in hypermethylation. Furthermore, >57% of the loci methylated in cell lines are never methylated in 114 primary malignancies studied. Seventy percent of loci hypermethylated in cell lines are hypermethylated in lines from more than one type of cancer. These data indicate that most CpG island hypermethylation observed in cancer cell lines is due to an intrinsic property of cell lines as opposed to the malignant tissue from which they originated.

Novel methylation targets in de novo acute myeloid leukemia with prevalence of chromosome 11 loci

Aberrant DNA methylation is believed to be important in tumorigenesis by causing either transcriptional inactivation of genes or chromosomal instability. Several laboratories have identified promoter hypermethylation of tumor suppressor genes in acute myeloid leukemia (AML). However, these studies do not provide a global assessment of overall methylation changes and do not allow the identification of novel methylated sequences. Previously, nonrandom CpG island methylation was reported in 17 adult de novo AML diagnostic samples when compared with the corresponding remission samples by means of restriction landmark genomic scanning (RLGS). That study has been expanded on by an analysis of a larger set of CpG islands (1740 vs 1184), which now provides details of 33 cloned methylated loci, including 21 known genes or expressed sequence tags. Five of these cloned loci appear to be methylated only in AML and not in the 6 solid tumors studied in this study (more than 98 samples analyzed). Chromosomal location was available for 30 of the 33 loci, and 5 of these 30 (17%) are localized to chromosome 11, suggesting a trend toward overrepresentation of methylation events on this chromosome. These results provide evidence for widespread aberrant methylation in AML, with identification of novel methylation targets, epigenetic changes that appear unique to AML, and apparent preferential methylation on chromosome 11.

Solute transport properties of compacted Ca-bentonite used in FEBEX project

The present Spanish concept of a deep geological high level waste repository includes an engineered clay barrier around the canister. The clay presents a very high sorption capability for radionuclides and a very small hydraulic conductivity, so that the migration process of solutes is limited by sorption and diffusion processes. Therefore, diffusion and distribution coefficients in compacted bentonite (i.e. in "realistic" liquid to solid ratio conditions) are the main parameters that have to be obtained in order to characterise solute transport that could be produced after the canister breakdown. Through-Diffusion (TD) and In-Diffusion (ID) experiments with HTO, Sr, Cs and Se were carried out using compacted FEBEX bentonite, which is the reference material for the Spanish concept of radioactive waste disposal. Experiments were interpreted by means of available analytical solutions that allow the estimation of diffusion coefficients and, in some cases, distribution coefficients. Analytical solutions are simple to use, but rely on hypotheses that do not hold in all the experiments. These experiments were interpreted also using an automatic parameter estimation code that overcomes the limitations of analytical solutions. Numerical interpretation allows the simultaneous estimation of porosity, diffusion and distribution coefficients, accounts for the role of porous sinters and time-varying boundary concentrations, and can use different types of raw concentration data.

Aberrant hypermethylation of the major breakpoint cluster region in 17p11.2 in medulloblastomas but not supratentorial PNETs

Deletions of 17p have been consistently reported in up to 50% of medulloblastomas (MBs), and the major breakpoint interval has been localized to chromosome segment 17p11.2. Based on several reports linking aberrant DNA methylation and chromosomal disruption, we examined the methylation pattern in this region by employing restriction landmark genomic scanning (RLGS). Several CpG islands located in the major breakpoint cluster region were identified using a bacterial artificial chromosome (BAC) contig of the breakpoint region. A long-range methylation map was established for 20 MBs and 5 supratentorial primitive neuroectodermal tumors (stPNETs). Selected CpG islands were examined using Southern and bisulfite sequencing analysis. Aberrantly hypermethylated CpG islands in 17p11. 2 were found in 33% of MBs. Interestingly, one CpG island was methylated in MBs, but not in any of the examined stPNETs. A BAC clone covering three of the methylated CpG islands was partially sequenced in the search for a potential tumor suppressor gene. None of the expressed sequence tag sequences and full-length mouse/human cDNAs that were associated with aberrant methylation showed a change in expression levels due to methylation. The potential link between chromosomal instability in 17p11.2 and hypermethylation in this region is discussed.

[Study on the correlation of estrogen receptor gene polymorphism to bone mineral density of radius in Chinese Han postmenopausal women in Beijing]

OBJECTIVE

To investigate the distribution of estrogen receptor (ER) gene polymorphism in postmenopausal Han women in Beijing as well as its correlation with bone mineral density (BMD) of radius.

METHODS

Xba I, and Pvu II polymorphism of ER gene were studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 99 healthy postmenopausal Han women. BMD of distal (spongy bone) and proximal (compact bone) radius were determined by dual-energy X-ray absorptiometry (DEXA) as well. The relationship between BMD and polymorphism of ER gene was analyzed by variance analysis.

RESULTS

Pvu II polymorphism of ER gene is not associated with BMD of both sites of radius (P > 0.05); while Xba I polymorphism of ER gene is significantly associated with BMD spongy and compact bone of radius (P < 0.05). Women with XX genotype have the lowest BMD T-score of -1.55 +/- 0.37 for the compact and -2.54 +/- 0.38 for the spongy, and those with xx genotype have the highest BMD T-score of -0.95 +/- 0.24 for compact and -1.74 +/- 0.16 for spongy.

CONCLUSION

There is a significant correlation of Xba I polymorphism of ER gene with BMD of distal and proximal radius. It is indicated that the difference in ER genotypes among individuals might influence the development of osteoporosis.

[The analysis of the axises of corneal astigmatism and total astigmatism in astigmatic patients]

PURPOSE

The axial amount and the relationship between the axises of corneal astigmatism and total astigmatism were statistically analyzed in ametropic patients, for the purpose of selecting the refractive correction, the base curve of contact lens, the axis of astigmatic contact lens, and providing the reference of operational amount of ecimer laser keratoplasty.

METHODS

The refractive state and the corneal curvature of ametropic patients were measured and consecutvely repeated 3 times in the same eye at the same state with the same autorefractometer in 107 cases. The detected axises of total astigmatism and corneal astigmatism were statistically analyzed through the computerized recording.

RESULTS

The mean angle between the axis of corneal astigmatism and the axis of total astigmatism was 5.73 degrees +/- 3.97 degrees in myopic patients, 3.13 degrees +/- 2.49 degrees in mixture astigmatism patients and 6.35 degrees +/- 4.20 degrees in hyperopic patients.

CONCLUSION

The angle between the axis of corneal astigmatism and the axis of total astigmatism in the refractive state was mainly caused by the difference of the axises of surface astigmatism of lens and cornea.

[Cerulenin inhibits growth of human colonic carcinoma in nude mice]

OBJECTIVE

To determine the effects of fatty acid synthase inhibitor, cerulenin, on tumor growth of human colonic carcinoma (LoVo) in nude mice.

METHODS

The transplantable colonic carcinoma cell line LoVo model was established in BALB/CA-nu/nu mice by subcutaneous implantation. Cerulenin was administrated by i.p. injection (80 mg/kg, 160 mg/kg each time) for 10 times. 17 days later the mice were killed and tumor size evaluated.

RESULTS

The size of tumors in cerulenin-treated group were significantly smaller than in control group and were similar to that of the 5-Fu treated group. Transmission electronic microscopy (TEM) revealed that death of LoVo cells treated by cerulenin was associated with apoptosis characterized by cell shrinkage, condensation and chromosome fragmentation. bcl-2 oncoprotein expression rate was significantly lower in cerulenin-treated group in comparing with the control group. The expression rate of bax was the opposite to that of bcl-2.

CONCLUSIONS

Cerulenin effectively suppresses the growth of human colonic carcinoma cells in vivo. The mechanism of cell death may be correlated with apoptosis, and bcl-2 and bax gene may play an important role in regulating cerulenin-induced apoptosis.

[Prognostic factors of clinical curative effect for malignant obstructive jaundice]

OBJECTIVE

To explore prognostic factors for clinical treatment of patients with malignant obstructive jaundice.

METHODS

17 variables from 216 consecutive patients with malignant obstructive jaundice admitted from 1990 to 1997 were included for statistical analysis.

RESULTS

The overall mortality was 19.9% (43/216), and the morbidity 37.5% (81/216). The morbidity of radical operation was higher than that of palliative operation (P < 0.01). There was a highly significant correlation between mortality, morbidity, ASA grade and duration of jaundice (P < 0.01). No correlation was seen between the mortality, type of operation and cause of jaundice. There was a highly significant correlation between the morbidity and the type of operation.

CONCLUSIONS

The choice of operation in patients with malignant obstructive jaundice is radical operation. Early diagnosis and choice of treatment are essential to improving carative effect.

[The molecular spectra and existence state of sulfonated phthalimidomethyl phthalocyanine hydroxyl aluminum as amphiphilic photosensitizer in aqueous alcoholic solutions and water]

The sulfonated phthalimidomethyl phthalocyanine hydroxyl aluminum (Al(OH)PcSP) is an amphiphilic photosensitizer which was proved to have the photodynamic activities against cancer. The electronic absorption spectra and aggregation state of the Al(OH)PcSP in aqueous alcoholic solutions and water were investigated. The results showed that the Al(OH)PcSP existed in the form of monomer in aqueous alcoholic solutions. The increase in the carbon chain and hydroxy of alcohol in solutions had no significant effects on the absorption spectra behaviors of Al(OH)PcSP. But in water, the Al(OH)PcSP existed in the equilibrium between monomer and dimer. The dimerization constant was 5.7307 x 10(4) mol-1.L. The characteristic absorption peak of the Q band of the Al(OH)PcSP dimer was red shifted to 740.5 nm from that of the monomer (676.5 nm), which contrast with those of other metal phthalocyanines dimer. The study on the fluorescence spectra of Al(OH)PcSP in aqueous alcoholic solutions suggested that the fluorescence of the dimer was weak.

The actin-driven movement and formation of acetylcholine receptor clusters

A new method was devised to visualize actin polymerization induced by postsynaptic differentiation signals in cultured muscle cells. This entails masking myofibrillar filamentous (F)-actin with jasplakinolide, a cell-permeant F-actin-binding toxin, before synaptogenic stimulation, and then probing new actin assembly with fluorescent phalloidin. With this procedure, actin polymerization associated with newly induced acetylcholine receptor (AChR) clustering by heparin-binding growth-associated molecule-coated beads and by agrin was observed. The beads induced local F-actin assembly that colocalized with AChR clusters at bead-muscle contacts, whereas both the actin cytoskeleton and AChR clusters induced by bath agrin application were diffuse. By expressing a green fluorescent protein-coupled version of cortactin, a protein that binds to active F-actin, the dynamic nature of the actin cytoskeleton associated with new AChR clusters was revealed. In fact, the motive force generated by actin polymerization propelled the entire bead-induced AChR cluster with its attached bead to move in the plane of the membrane. In addition, actin polymerization is also necessary for the formation of both bead and agrin-induced AChR clusters as well as phosphotyrosine accumulation, as shown by their blockage by latrunculin A, a toxin that sequesters globular (G)-actin and prevents F-actin assembly. These results show that actin polymerization induced by synaptogenic signals is necessary for the movement and formation of AChR clusters and implicate a role of F-actin as a postsynaptic scaffold for the assembly of structural and signaling molecules in neuromuscular junction formation.

The dual role of IL-2 in the generation and maintenance of CD8+ memory T cells

The mechanisms responsible for the generation and maintenance of T cell memory are unclear. In this study, we tested the role of IL-2 in allospecific CD8+ T cell memory by analyzing the long-term survival, phenotype, and functional characteristics of IL-2-replete (IL-2+/+) and IL-2-deficient (IL-2-/-) CD8+ TCR-transgenic lymphocytes in an adoptive transfer model. We found that IL-2 is not essential for the in vivo generation, maintenance, or recall response of CD8+ memory T cells. However, IL-2 increased the size of the CD8+ memory pool if present at the time of initial T cell activation but reduced the size of the pool if present during memory maintenance by inhibiting the proliferation of CD8+ memory T cells. Thus, IL-2-based vaccine strategies or immunosuppressive regimens that target IL-2 should take into account the divergent roles of IL-2 in CD8+ T cell immunity.

Alloantigen-driven T cell death mediated by Fas ligand and tumor necrosis factor-alpha is not essential for the induction of allograft acceptance

BACKGROUND

Fas ligand (FasL)-Fas and tumor necrosis factor alpha (TNFalpha)-tumor necrosis factor receptor (TNFR) interactions regulate immune responses and contribute to self-tolerance by mediating antigen-driven T cell apoptosis. It is not known whether FasL and TNFalpha, expressed by the recipient's lymphoid or nonlymphoid cells, are essential for the apoptosis of alloreactive T lymphocytes and the induction of allograft acceptance.

METHODS

We compared the survival of fully allogeneic vascularized cardiac allografts between wild-type (wt) and FasL-mutant (gld) recipient mice. In addition, we studied cardiac allograft survival in gld mice injected with TNFalpha-neutralizing antibody. Allograft acceptance (graft survival >100 days) was induced by treating the recipients with CTLA4Ig, a recombinant fusion protein that blocks B7-CD28 T cell costimulation. In vivo alloantigen-driven apoptosis of mature CD4+ and CD8+ T lymphocytes was analyzed in mice repeatedly stimulated with allogeneic splenocytes.

RESULTS

We found that CTLA4Ig induces 100% long-term acceptance of cardiac allografts in wt and gld mice. Similarly, CTLA4Ig induced 100% allograft acceptance in gld recipients injected with TNFalpha-neutralizing antibody. In vivo alloantigen-driven apoptosis of mature CD4+ and CD8+ T cells was significantly reduced in gld mice and in wt mice treated with anti-TNFalpha antibody. However, neutralizing TNFalpha activity in gld mice failed to abrogate alloantigen-driven T cell apoptosis.

CONCLUSIONS

These data indicate that: (1) FasL and TNFalpha expression are not obligatory for the induction of long-term allograft acceptance by CTLA4Ig and (2) FasL- and TNFalpha-independent death pathways contribute to alloantigen-driven T cell apoptosis.

[Proliferation inhibition and apoptosis induction of K562 cells by fatty acid synthase inhibitor--cerulenin]

OBJECTIVE

To investigate the effect of fatty acid synthase (FAS) inhibitor--cerulenin on K562 leukemia cells and its mechanism.

METHODS

Inhibition rate of cerulenin on K562 leukemia cells was assayed by MTT method, cell apoptosis by flow cytometry (FCM) and agarose gel electrophoresis.

RESULTS

When treated with 10(-9) - 10(-5) mol/L of cerulenin for 24 h, the proliferation of K562 cells was obviously inhibited with dose related effect. At the same concentrations, the inhibition rates of human skin fibroblasts were all lower than 30%. When K562 cells were treated for 12 h with 50 microg/ml and 60 microg/ml of cerulenin, the apoptosis rate revealed by FCM was 42.30% and 38.8%, respectively, and DNA agarose gel electrophoresis showed the typical DNA ladder of apoptosis.

CONCLUSION

Fatty acid synthase inhibitor--cerulenin inhibits proliferation of K562 cells but not of human fibroblasts. Cerulenin mediated cytotoxity is due to apoptosis induction. Fatty acid synthase might be a potential target for anti-leukemia.

[An experimental study on cerulenin induced apoptosis of human colonic cancer cells]

OBJECTIVE

To investigate whether cerulenin could induce apoptosis and suppress the proliferation of human colonic cancer cells.

METHODS

Cell morphology, microculture tetrazolium assay (MTT), agarose gel electrophoresis and flow cytometry assays were performed to identify the inhibitory effect on cell proliferation and the induction of apoptosis in human colonic cancer cells (LoVo).

RESULTS

Cerulenin was able to induce LoVo cells death via apoptosis. Cerulenin also inhibited the proliferation of LoVo cells in vitro and was dose-dependent. Nuclear DNA of apoptotic cells displayed ladder bands characteristic of internucleosomal DNA fragmentation and apoptotic peak. The inhibitory effect of cerulenin on proliferation of LoVo cells was associated with cell cycle arrest from S to G(2)-M phase transition and with induction of apoptosis. In contrast, cerulenin could not affect the proliferation of human fibroblasts in vitro.

CONCLUSION

The fatty acid synthase inhibitor, cerulenin, enables to induce cell apoptosis and to suppress the growth of human colonic cancer cells by inhibition of the synthesized fatty acids endogenously in the cancer cells.

Highly diastereoselective alpha-mannopyranosylation in the absence of participating protecting groups

S-Phenyl 2,6-di-O-benzyl-3,4-O-(2',3'-dimethoxybutane-2', 3'-diyl)-1-thia-alpha-D-mannopyranoside and its sulfoxide, following activation at -78 degrees C with benzenesulfenyl triflate or triflic anhydride, respectively, provide the corresponding alpha-mannosyl triflate as demonstrated by NMR spectroscopy. On addition of an acceptor alcohol alpha-mannosides are then formed. Similarly, S-phenyl 2,3-O-carbonyl-4, 6-O-benzylidene-1-thia-alpha-D-mannopyranoside and ethyl 3-O-benzoyl-4, 6-O-benzylidene-2-O-(tert-butyldimethylsilyl)-1-thia-alpha-D-mannopyr anoside both provide alpha-mannosides on activation with benzenesulfenyl triflate followed by addition of an alcohol. These results stand in direct contrast to the highly beta-selective couplings of comparable glycosylations with 2,3-di-O-benzyl-4, 6-O-benzylidene protected mannosyl donors and draw attention to the subtle interplay of reactivity and structure in carbohydrate chemistry.

[Magnetic resonance angiography in assessing changes of pre-and post-disconnective portal system in patients with portal hypertension]

OBJECTIVE

To evaluate the role of magnetic resonance angiography (MRA) in assessing the portal system changes in patients with portal hypertension after pericardial devascularization and splenectomy.

METHODS

The portal diameter, blood velocity and flow, collateral circulation, variceal vein and other portal parameters of 15 patients with portal hypertension receiving pericardial devascularization and splenectomy and splenectomy were comparatively evaluated with Siemens 1.5 T MRI 1 week before operation and 2 weeks after operation.

RESULTS

The portal diameters decreased after operation, with the disappearance or alleviation of esophageal and fundal variceal veins. In 15 patients, 9 showed. The blood velocity and flow of the portal veins were lower postoperatively. than those preoperatively; In 15 patients, 9 showed increased gastric imaging intensity after operation.

CONCLUSIONS

MRA can provide high quality and concrete 3-dimensional information about the portal system and hemodynamics of portal hypertensive patients. It is an important non-invasive way in evaluating the effects of operations and long-term follow-up. Postoperative gastric venous congestion possibly causes increased portal hypertensive gastropathy after disconnection.

Expression of Acidothermus cellulolyticus endoglucanase E1 in transgenic tobacco: biochemical characteristics and physiological effects

The expression of the Acidothermus cellulolyticus endoglucanase E1 gene in transgenic tobacco (Nicotiana tabacum) was examined in this study, where E1 coding sequence was transcribed under the control of a leaf specific Rubisco small subunit promoter (tomato RbcS-3C). Targeting the E1 protein to the chloroplast was established using a chloroplast transit peptide of Rubisco small subunit protein (tomato RbcS-2A) and confirmed by immunocytochemistry. The E1 produced in transgenic tobacco plants was found to be biologically active, and to accumulate in leaves at levels of up to 1.35% of total soluble protein. Optimum temperature and pH for E1 enzyme activity in leaf extracts were 81 degrees C and 5.25, respectively. E1 activity remained constant on a gram fresh leaf weight basis, but dramatically increased on a total leaf soluble protein basis as leaves aged, or when leaf discs were dehydrated. E1 protein in old leaves, or after 5 h dehydration, was partially degraded although E1 activity remained constant. Transgenic plants exhibited normal growth and developmental characteristics with photosynthetic rates similar to those of untransformed SR1 tobacco plants. Results from these biochemical and physiological analyses suggest that the chloroplast is a suitable cellular compartment for accumulation of the hydrolytic E1 enzyme.

Hypoxic stimulation of vascular endothelial growth factor expression in activated rat hepatic stellate cells

The tissue repair response to hypoxic stimuli during wound healing includes enhanced production of angiogenic factors, such as vascular endothelial growth factor (VEGF). Hepatic stellate cells are oxygen-sensing cells, capable of producing VEGF. We hypothesized that hypoxia-stimulated signaling in activated stellate cells mediate VEGF secretion during liver injury. The specific aim was to evaluate the effect of hypoxia on the gene expression of VEGF in HSC-T6 cells, an immortalized rat hepatic stellate cell line, and in rat primary cultures of stellate cells. Hypoxic induction of VEGF mRNA was dose- and time-dependent. The hypoxic stimulation of VEGF messenger RNA (mRNA) correlated with the secretion of VEGF protein in conditioned media by hypoxic T6 cells. S-Nitroso-N-acetyl-D, L-penicillamine (SNAP), a nitric oxide (NO) donor, and desferrioxamine (DFx) and cobalt chloride, mimics of cellular hypoxia, similarly stimulated VEGF mRNA expression and secretion. Four previously described splice variants of the VEGF mRNA (VEGF-120, 144, 164, 188) were detected in both normoxic- or hypoxic-activated stellate cells. There was differential expression of the VEGF receptors, Flt-1 and Flk-1, in hypoxic T6 cells. Hypoxic conditions selectively stimulated Flt-1 mRNA expression, whereas Flk-1 mRNA remained unchanged. Hypoxic induction of VEGF was also demonstrated in primary stellate cell cultures and after in vivo injury. Hypoxia stimulates cell signaling in stellate cells, culminating in the rapid induction of VEGF and Flt-1 mRNA expression and VEGF secretion. The hypoxic induction of VEGF is mimicked by NO and may be of mechanistic importance in the pathogenesis of hepatic wound healing and hepatocarcinogenesis.

A sensitive HPLC technique for the quantitation of dauricine

To establish the determination method of dauricine (Dau) concentration in rats' blood and other biological samples, a reverse-phase HPLC method was adopted. Under the given condition, dauricine could be well separated. The retention time (tR) of Dau and its internal standard, daurisoline were 9.2 and 6.1 respectively. The detection limit was 10(-2) mg/ml. The absolute recoveries of all kinds of samples were above 70%, and the relative ones were over 85%. A good liner relationship has been obtained over the entire range of 0.030 to 3.000 mg/L in blood samples and 0.050 to 5.000 mg/L in other tissue samples. The intraday and interday coefficients of variation were below 10%. The results showed that the method can be used for detecting Dau in all kinds of biological samples.

Metabolism of dauricine and identification of its main metabolites

To study the metabolism of dauricine in vivo and in vitro and identify the structure of its main metabolites, urine of rats after drug administration as the samples of dauricine metabolism in vivo was studied. Rat liver S9 fraction was prepared and the oxygenation metabolism system reconstituted to perform phase I reaction of dauricine in vitro. TLC, HPLC-DAD and MS were used to analyze and identify dauricine and its main phase I metabolites in the samples. The results showed that besides the untransformed dauricine, in the urine samples there was little product of X' which had the same features of TLC, HPLC-DAD and MS as those of N-desmethyl dauricine (N-ddau). Part of dauricine could be transformed to a main metabolite X after incubating with S9 fraction in appropriate conditions. The molecular ion peak of X was m/z 611. The full scan MS2 spectrum of m/z 611 peak from S9 sample were m/z 580, m/z 566, m/z 552, m/z 206, which were same as those of N-ddau. Liver is the major organ for dauricine metabolism and part of dauricine is biotransformed by liver. The major metabolite is considered to be N-ddau.

The role of cytokines, CTLA-4 and costimulation in transplant tolerance and rejection

T cell costimulation and cytokine production play an important role in generating the alloimmune responses that lead to allograft rejection. Recent data, however, provide evidence that costimulatory molecules, such as B7-1 and B7-2, and T cell activating cytokines, such as IFN-gamma and IL-2, also trigger negative feedback mechanisms in T lymphocytes which limit alloimmune responses. These feedback mechanisms are essential for the induction of long-term allograft acceptance and, in certain situations, transplantation tolerance.

The role of the common cytokine receptor gamma-chain in regulating IL-2-dependent, activation-induced CD8+ T cell death

IL-2-dependent, activation-induced T cell death (AICD) plays an important role in peripheral tolerance. Using CD8+ TCR-transgenic lymphocytes (2C), we investigated the mechanisms by which IL-2 prepares CD8+ T cells for AICD. We found that both Fas and TNFR death pathways mediate the AICD of 2C cells. Neutralizing IL-2, IL-2R alpha, or IL-2R beta inhibited AICD. In contrast, blocking the common cytokine receptor gamma-chain (gamma c) prevented Bcl-2 induction and augmented AICD. IL-2 up-regulated Fas ligand (FasL) and down-regulated gamma c expression on activated 2C cells in vitro and in vivo. Adult IL-2 gene-knockout mice displayed exaggerated gamma c expression on their CD8+, but not on their CD4+, T cells. IL-4, IL-7, and IL-15, which do not promote AICD, did not influence FasL or gamma c expression. These data provide evidence that IL-2 prepares CD8+ T lymphocytes for AICD by at least two mechanisms: 1) by up-regulating a pro-apoptotic molecule, FasL, and 2) by down-regulating a survival molecule, gamma c.

Particle-Bubble Attachment in Mineral Flotation

Attachment efficiencies of rough, angular, methylated quartz particles with nitrogen bubbles are derived from experimental capture efficiency data in conjunction with a collision model termed the Generalized Sutherland Equation (GSE). The methylated quartz particles ranged in size from 7.5 to 70 µm equivalent diameter and had advancing contact angles between 33 degrees and 74 degrees. They heterocoagulated with nitrogen bubbles between 0.77 and 1.52 mm in diameter in 0, 0.01, or 0.1 mol dm(-3) KCl. The attachment efficiencies decreased with increasing particle size and bubble size, but increased with particle contact angle and KCl electrolyte concentration. These attachment efficiency data were then used to test the Dobby-Finch attachment model for potential flow conditions. The latter model was modified so that the conditions of approach of the particle toward the bubble surface are the same as those defined previously in the GSE collision model (Dai et al., 1998, J. Colloid Interface Sci. 197, 275). Satisfactory agreement was obtained between the experimental attachment efficiencies obtained in this study and those calculated with the Dobby-Finch model. In the attachment efficiency calculations, the induction time (t(ind)) varied with particle size (d(p)) according to the well-known equation, t(ind) = Ad(B)(p). The parameter B, with a value of 0.6, was found to be independent of particle size, particle contact angle, bubble size, and KCl electrolyte concentration. Conversely, the value of the parameter A was dependent on the particle contact angle, especially for contact angles smaller than 50 degrees, and on the bubble size but to a lesser extent on the electrolyte concentration. The value of A decreased with an increase in particle contact angle and an increase in bubble size. The values of the induction time obtained in this study are in a reasonable agreement with experimental and calculated induction times reported in the literature. Copyright 1999 Academic Press.

Increased susceptibility to immunologically mediated glomerulonephritis in IFN-gamma-deficient mice

It is postulated that IFN-gamma confers susceptibility to immunologically mediated tissue injury. To test this hypothesis, we compared the intensity of accelerated anti-glomerular basement membrane glomerulonephritis between wild-type (IFN-gamma+/+) and IFN-gamma gene knockout (IFN-gamma-/-) mice. This disease model is initiated by binding of heterologous (sheep) anti-glomerular basement membrane Abs to the glomeruli of mice preimmunized with sheep IgG. The secondary cellular and humoral immune responses to the planted Ag then lead to albuminuria and glomerular pathology. We found that IFN-gamma-/- mice or IFN-gamma+/+ mice injected with IFN-gamma-neutralizing Ab develop worse albuminuria and glomerular pathology than IFN-gamma+/+ mice. The humoral response to sheep IgG (serum mouse anti-sheep IgG titers and intraglomerular mouse IgG deposits) was comparable in the IFN-gamma+/+ and IFN-gamma-/- groups. In contrast, IFN-gamma-/- mice mounted a stronger cellular immune response (cutaneous delayed-type hypersensitivity reaction) to sheep IgG than IFN-gamma+/+ mice. These findings provide evidence that endogenous IFN-gamma has a protective role in immunologically mediated glomerulonephritis initiated by foreign Ags.

Regulation of alloantigen-mediated T-cell proliferation by endogenous interferon-gamma: implications for long-term allograft acceptance

BACKGROUND

Recent data suggest that interferon (IFN)-gamma is not an essential mediator of acute rejection but, instead, is critical for the induction of long-term allograft acceptance. The in vivo mechanisms by which endogenous IFN-gamma regulates the alloimmune response and thus facilitates the induction of long-term allograft survival are not known.

METHODS

We examined long-term cardiac and skin allograft survival, alloantigen-induced T-cell proliferation, and alloantigen-induced T-cell apoptosis in wild-type (IFN-gamma+/+) and IFN-gamma gene-knockout (IFN-gamma-/-) mice treated with either B7-CD28 T-cell costimulation blockade alone or B7-CD28 T-cell costimulation blockade combined with donor splenocyte transfusion.

RESULTS

We found that IFN-gamma is essential for long-term allograft survival induced by treating mice with either B7-CD28 T-cell costimulation blockade alone or B7-CD28 T-cell costimulation blockade combined with donor splenocyte transfusion. Alloantigen-induced T-cell proliferation in vivo was significantly greater in IFN-gamma-/- mice than in IFN-gamma+/+ mice, and T-cell costimulation blockade abrogated alloantigen-induced T-cell proliferation in wild-type mice but failed to do so in mice that lack IFN-gamma. In contrast, alloantigen-induced T lymphocyte apoptosis in vivo did not differ between IFN-gamma+/+ and IFN-gamma-/- mice, and T-cell costimulation blockade enhanced alloantigen-induced T-cell apoptosis in both mouse strains.

CONCLUSIONS

These data suggest that endogenous IFN-gamma facilitates the induction of long-term allograft survival by limiting the proliferation of alloactivated T lymphocytes. The data also suggest that B7-CD28 T-cell costimulation blockade exerts immunosuppressive actions by inhibiting the proliferation of activated T lymphocytes and by promoting their apoptosis.

A new tool for the rapid cloning of amplified and hypermethylated human DNA sequences from restriction landmark genome scanning gels

Restriction landmark genome scanning (RLGS) is an effective genome-scanning technique capable of identifying DNA amplification and aberrant DNA methylation. Previously published methods for the cloning of human DNA fragments from RLGS gels have been successful only for high-copy-number fragments (repetitive elements or DNA amplifications). We present here the first technique capable of efficiently cloning single-copy human DNA fragments ("spots") identified in RLGS profiles. This technique takes advantage of a plasmid-based, human genomic DNA, NotI/EcoRV boundary library. The library is arrayed in microtiter plates. When clones from a single plate are pooled and mixed with genomic DNA, the resultant RLGS gel is a normal profile with a defined set of spots showing enhanced intensity for that particular plate. This was performed for a set of 32 plates as well as their pooled rows and columns. Thus, we have mapped individual RLGS spots to exact plate, row, and column addresses in the library and have thereby obtained immediate access to these clones. The feasibility of the technique is demonstrated in examples of cloning methylated DNA fragments identified in human breast tumor and testicular tumor RLGS profiles and in the cloning of an amplified DNA fragment identified in a human medulloblastoma RLGS profile.

Interferon-gamma is necessary for initiating the acute rejection of major histocompatibility complex class II-disparate skin allografts

BACKGROUND

Although interferon (IFN)gamma has immunostimulatory functions, it is not essential for the acute rejection of fully allogeneic grafts in mice. It is not known whether IFNgamma plays a critical role in the acute rejection of MHC class I- or MHC class II-disparate allografts.

METHODS

We studied the survival of skin allografts transplanted from fully allogeneic (BALB/c), MHC class I-disparate (bml), or MHC class II-disparate (bm12) donors to C57BL/6 wild-type (IFNgamma+/+) and IFNgamma gene-knockout (IFNgamma-/-) recipients. We also investigated the in vitro responses of IFNgamma+/+ and IFNgamma-/- T cells to MHC class II-disparate splenocytes.

RESULTS

We found that IFNgamma-/- recipients reject BALB/c and bml skin grafts at the same rate as IFNgamma+/+ mice but are not capable of rejecting bm12 skin. Despite the inability of IFNgamma-/- mice to reject bm12 skin grafts, IFNgamma-/- T cells displayed vigorous proliferation and cytotoxic responses when stimulated with bm12 splenocytes in vitro. Furthermore, priming IFNgamma-/- recipients with bm12 splenocytes enabled these mice to reject bm12 skin grafts at a normal rate and to mount a cutaneous delayed-type hypersensitivity response to the bm12 antigen.

CONCLUSION

The data demonstrate that IFNgamma is not necessary for generating effector mechanisms associated with acute transplant rejection but that it is required for initiating alloimmune responses to MHC class II-disparate skin grafts.

[Progress of speeding up measles control strategies in Anhui]

OBJECTIVE

To speed up measles control program.

METHODS

Catching-up immunization campaigns on measles have been conducted among the children aged 1-6 years in three prefectures of Anhui by the end of 1997 and the measles surveillance system was established at the beginning of 1998. IgM antibody of measles and rubella was tested with ELISA and IgG antibody was examined with HI test.

RESULTS

The positive rate of measles antibody among children was 100%, GMT increased from 1:18.97 to 1:43.45 after the campaigns. Measles cases in the three districts from January to June 1998 had a 87.71% decrease, comparing with the same period of 1997 with measles outbreak avoided. There were 105(58.01%) cases of measles with positive IgM and 32(17.68%) cases of rubella with positive IgM out of 181 testees having fever and rash illnesses.

CONCLUSION

Results indicated the programs as catching-up immunization campaigns on measles and keeping high level of MV immunization, establishing measles surveillance system with improvement of its sensibility together with rubella control program all seemed to be important strategies in speeding up the positive outcome of measles control.

Expression of Trichoderma reesei Exo-Cellobiohydrolase I in Transgenic Tobacco Leaves and Calli

Expression of Trichoderma reesei exo-cellobiohydrolase I (CBHI) gene in transgenic tobacco was under the control of CaMV 35S promoter. In transgenic leaf tissues, CBHI activity up to 66.1 micromol/h/g total protein was observed. In transgenic calli, the highest CBHI activity was 83.6 micromol h/g total protein. Protein immunoblot analysis confirms the presence of CBHI enzyme in both transgenic calli and leaf tissues. CBHI expression levels accounted for about 0.11% and 0.082% of total protein in transgenic leaf tissues and calli, respectively. Furthermore, expression of CBHI gene did not affect normal growth and development of transgenic plants.

[Simultaneous determination of eight kinds of conjunct bile acids in human bile by R-HPLC]

A method for the simultaneous determination of eight kinds of conjunct bile acids in human bile was developed by HPLC. They were separated on a YWG-C18 (3 microns) column at 30 degrees C, with methanol/water (65/35, V/V, pH3.0) as mobile phase, and detection wavelength at UV 210 nm. The linear ranges were 50-1,000 microns.ml-1, the recoveries were 91.2%-108.6%. The biles of 30 cases with cholelithiasis cholecystolithiasis and 20 cases without gallstone were detected by HPLC. The results showed that the constitution of bile acids was different between patients with cholelithiasis cholecystolithiasis and patients without gallstone.

Impaired alloantigen-mediated T cell apoptosis and failure to induce long-term allograft survival in IL-2-deficient mice

We examined whether IL-2 regulates alloimmune responses by studying allograft survival in wild-type (IL-2+/+) and IL-2 gene-knockout (IL-2-/-) mice. The acute rejection of vascularized, cardiac allografts and the generation of allospecific CTLs were not impaired in the absence of IL-2. In contrast, blocking the B7-CD28 T cell costimulation pathway with CTLA4Ig induced long-term allograft survival (> 100 days) in IL-2+/+ recipients but failed to do so in IL-2-/- mice or in wild-type mice that had been treated with IL-2-neutralizing Ab around the time of transplantation. Allografts rejected by IL-2-/- recipients exhibited extensive mononuclear cell infiltrates despite CTLA4Ig administration. In vivo allostimulation in the absence of IL-2 led to exaggerated T lymphocyte proliferation and impaired apoptosis of activated T cells in untreated and CTLA4Ig-treated mice. These findings indicate that endogenous IL-2 is required for the induction of long-term allograft survival, and that IL-2 regulates alloimmune responses by preparing activated T lymphocytes for alloantigen-induced apoptosis.

A role of tyrosine phosphatase in acetylcholine receptor cluster dispersal and formation

Innervation of the skeletal muscle involves local signaling, leading to acetylcholine receptor (AChR) clustering, and global signaling, manifested by the dispersal of preexisting AChR clusters (hot spots). Receptor tyrosine kinase (RTK) activation has been shown to mediate AChR clustering. In this study, the role of tyrosine phosphatase (PTPase) in the dispersal of hot spots was examined. Hot spot dispersal in cultured Xenopus muscle cells was initiated immediately upon the presentation of growth factor-coated beads that induce both AChR cluster formation and dispersal. Whereas the density of AChRs decreased with time, the fine structure of the hot spot remained relatively constant. Although AChR, rapsyn, and phosphotyrosine disappeared, a large part of the original hot spot-associated cytoskeleton remained. This suggests that the dispersal involves the removal of a key linkage between the receptor and its cytoskeletal infrastructure. The rate of hot spot dispersal is inversely related to its distance from the site of synaptic stimulation, implicating the diffusible nature of the signal. PTPase inhibitors, such as pervanadate or phenylarsine oxide, inhibited hot spot dispersal. In addition, they also affected the formation of new clusters in such a way that AChR microclusters extended beyond the boundary set by the clustering stimuli. Furthermore, by introducing a constitutively active PTPase into cultured muscle cells, hot spots were dispersed in a stimulus- independent fashion. This effect of exogenous PTPase was also blocked by pervanadate. These results implicate a role of PTPase in AChR cluster dispersal and formation. In addition to RTK activation, synaptic stimulation may also activate PTPase which acts globally to destabilize preexisting AChR hot spots and locally to facilitate AChR clustering in a spatially discrete manner by countering the action of RTKs.

Oncogenic Abl and Src tyrosine kinases elicit the ubiquitin-dependent degradation of target proteins through a Ras-independent pathway

Oncogenic forms of the Abl and Src tyrosine kinases trigger the destruction of the Abi proteins, a family of Abl-interacting proteins that antagonize the oncogenic potential of Abl after overexpression in fibroblasts. The destruction of the Abi proteins requires tyrosine kinase activity and is dependent on the ubiquitin-proteasome pathway. We show that degradation of the Abi proteins occurs through a Ras-independent pathway. Significantly, expression of the Abi proteins is lost in cell lines and bone marrow cells isolated from patients with aggressive Bcr-Abl-positive leukemias. These findings suggest that loss of Abi proteins may be a component in the progression of Bcr-Abl-positive leukemias and identify a novel pathway linking activated nonreceptor protein tyrosine kinases to the destruction of specific target proteins through the ubiquitin-proteasome pathway.

IFN-gamma is critical for long-term allograft survival induced by blocking the CD28 and CD40 ligand T cell costimulation pathways

It is postulated that IFN-gamma production hinders long-term acceptance of transplanted organs. To test this hypothesis, we compared survival of skin and heart allografts in wild-type (IFN-gamma+/+) mice to that in IFN-gamma gene knockout (IFN-gamma-/-) mice. We found that perioperative blockade of the CD28 and/or CD40 ligand T cell costimulation pathways induces long-term skin and heart allograft survival in IFN-gamma+/+ recipients but fails to do so in IFN-gamma-/- mice or in wild-type mice treated with IFN-gamma-neutralizing Ab at the time of transplantation. In vitro studies showed that endogenously produced IFN-gamma down-regulates T cell proliferation and CTL generation in MLCs. These actions of IFN-gamma were not mediated by TNF-alpha production or Fas-Fas ligand interactions. In vivo studies revealed exaggerated expansion and, subsequently, impaired deletion of superantigen-reactive T lymphocytes in IFN-gamma-/- mice injected with staphylococcal enterotoxin B. Taken together, our findings indicate that IFN-gamma does not hinder but instead facilitates induction of long-term allograft survival possibly by limiting expansion of activated T cells.

Fluorescence microscopy of calcium and synaptic vesicle dynamics during synapse formation in tissue culture

The signal transduction process involved in the development of the nerve terminal is an intriguing question in developmental neurobiology. During the formation of the neuromuscular junction, presynaptic development is induced by growth cone's contact with the target muscle cell. Fluorescence microscopy with specific markers has made it possible to follow signalling events during this process. By using fluorescent calcium indicators, such as fura-2 and fluo-3, we found that a rise in intracellular calcium is elicited in the growth cone upon its contact with a target, and this calcium signal can also be elicited by local application of basic fibroblast growth factor. To monitor the clustering of synaptic vesicles in response to target contact, the fluorescent vesicular probe FMl-43 was used. With this probe, we observed that packets of synaptic vesicle are already present along the length of naïve neurite, which has not encountered its synaptic target. The activity-dependent loading of FMl-43 indicates that these packets can undergo exocytosis and endocytosis upon depolarization. Time-lapse recording showed that these packets are quite mobile. Upon target contact, synaptic vesicles become clustered and immobilized at the contact site. The methodology and instrumentation used in these studies are described in this article.

The Inertial Hydrodynamic Interaction of Particles and Rising Bubbles with Mobile Surfaces

The collection efficiency of single bubbles rising through a very dilute pulp of hydrophobized quartz particles has been determined. Measurements have been performed under conditions in which the bubble surface is mobile, as a function of electrolyte concentration, particle diameter (7 to 70 &mgr;m), bubble diameter (0.77 x 10(-3) to 1.52 x 10(-3) m), and particle advancing water contact angle. Situations in which the product of attachment and stability efficiency is at its maximum value have been identified, permitting a stringent, critical test of collision theory to be performed. A collision theory has been developed which accounts for the influence of positive and negative inertial forces in the case of bubbles with mobile surfaces. The approach considers only long-range hydrodynamic interactions under conditions where short-range interactions are strongly suppressed (i.e., high particle contact angle and high electrolyte concentrations) and attachment occurs at first collision. In this instance, good agreement between theory and experiment is achieved for particle diameters between 7 and 60 &mgr;m and Stokes numbers up to 0.27. The analytical equation developed is termed the generalized Sutherland equation (GSE). Copyright 1998 Academic Press. Copyright 1998Academic Press