[Fluorescence enhancement and laser behavior of Rhodamine 6G in micell]

Fluorescence of Rhodamine 6G in aqueous solution is effectively enhanced by using anionic sodium dodecylsulfate (SDS) surfactant. When the concentration of Rhodamine 6G is 5.47 x 10(-7) mol.L-1 and 5.47 x 10(-4) mol.L-1, maximal enhancement ratio can be 1.95 and 9.7, respectively. In the latter case, using SDS can reduce the threshold and improve the energy conversion efficiency of the dye laser of Rhodamine 6G. In the absence of SDS, the laser threshold power density is near 65 MW.cm-2. While in the present of SDS, the threshold is reduced to 0.8 MW.cm-2. The laser energy conversion efficiency can reach 25% when the pumping power density is 65 MW.cm-2. We also observed the red shifts of absorption spectrum, fluorescence spectrum and the dye laser spectrum in the present of SDS. The physical mechanism of the phenomena is discussed.

[The roles of vascular endothellial growth factor and endothelin-1 on pulmonary vascular remodelling in rats with hypoxia-induced pulmonary hypertension]

OBJECTIVE

To investigate the roles of the vascular endothelial growth factor(VEGF) and endothelin-1(ET-1) in pulmonary vascular remodelling in rats with hypoxia-induced pulmonary hypertension(HPH) and the effect of pinacidil on VEGF and ET-1 in rats with HPH.

METHOD

46 male Wister rats were divided into three groups i.e. control group, hypoxic group and treated group (hypoxic rats treated with pinacidil for 4 weeks). Rat models with chronic HPH were established by chronic hypobaric hypoxia [(10.0 +/- 0.5)% O2, 4 weeks]. The levels of VEGF and ET-1 in serum and the mean pulmonary arterial pressure (mPAP) and the weight ratio of right ventricle (RV)/left ventricle and septum (LV + S) [RV/(LV + S)] were measured and the small pulmonary arterial morphologic changes were observed with morphometric analysis under microscopes in the three groups.

RESULTS

(1) The levels of VEGF[(118.73 +/- 55.40) ng/L] and ET-1[(221.2 +/- 56.2) ng/L] in serum, mPAP [(28.4 +/- 2.8) mm Hg, 1 mm Hg = 0.133 kPa] and RV/(LV + S) (0.296 +/- 0.033) were significantly higher in the hypoxic group than those in the control group (P < 0.01). Morphometry showed that the external diameter of the small pulmonary arteries became smaller and the ratio of vascular wall thickness to external diameter (MT%) (25.70 +/- 2.58)% and ratio of vascular wall area to total area (MA%) (75.300 +/- 5.600)% significantly increased in the hypoxic group. (2) The levels of VEGF[(78.20 +/- 16.45) ng/L] and ET-1[(181.6 +/- 30.5) ng/L] in serum, mPAP[(23.3 +/- 2.6) mm Hg], RV/(LV + S) (0.266 +/- 0.037), MT%(22.10 +/- 2.51)% and MA% (66.900 +/- 0.061)% significantly decreased in the treated group.

CONCLUSION

VEGF and ET-1 play important roles in the development of HPH and pulmonary vascular remodelling. Pinacidil may partly inhibit the development of HPH and pulmonary vascular remodelling by decreasing VEGF and ET-1.

[p53 and vascular endothelial growth factor expression in astrocytoma and their relation to angiogenesis]

OBJECTIVE

This investigation was done to show the pathological importance of p53 protein detection, vascular endothelial growth factor expression (VEGF) and intratumoral microvessel density (IMVD) in astrocytoma.

METHODS

The surgical specimens from 60 brain astrocytoma patients were stained immunohistochemically for p53 and IMVD expressions. IMVD was calculated by labeling the endothelial cells of the blood vessels within the tumor.

RESULTS

p53, VEGF expression were closely correlated with histopathological grade of astrocytoma. Positive p53 protein accumulation and VEGF expression were found in 45.0% (27/60) and 65.0% (39/60) of tumors. The conformation rate of p53 and VEGF was 70.0% (42/60). IMVD was significantly higher in the p53-positive or VEGF-positive tumors than in the negative ones (P < 0.05). Comparing the IMVD in p53+/VEGF+ group, p53-/VEGF+ group and p53+/VEGF- group, p53-/VEGF- group, its difference was also highly significant (P < 0.05).

CONCLUSION

(1) p53 protein detection, VEGF expression and IMVD can be considered as a biological indicator of malignant potential in brain astrocytoma patients and (2) p53 and VEGF expressions, both contributing to the tumor neovascularization, may be helpful in the understanding of intra-tumoral angiogenetic mechanism in the future.

Growth inhibition due to complementation of transforming growth factor-beta receptor type II-defect by human chromosome 3 transfer in human colorectal carcinoma cells

The transforming growth-beta receptor type II (TGF-beta RII) gene is one of the target genes of the DNA mismatch repair (MMR) defect. The human colorectal carcinoma cell line HCT116 has mutations in the hMLH1 gene and in the microsatellite region of the TGF-beta RII gene, both located on the short arm of chromosome 3. Introduction of the wild-type hMLH1 gene on transferred human chromosome 3 restores many characteristics of MMR-deficiency in HCT116. In this study, we determined whether transfer of chromosome 3 into HCT116 also complements the TGF-beta RII gene defect. We compared in vitro growth characteristics between HCT116 and HCT116 with a transferred chromosome 3 (HCT116 + ch3). The growth was suppressed in HCT116 + ch3 compared with parental HCT116. This suppression was abolished by frequent replacement with fresh medium, suggesting that the autocrine TGF-beta-TGF-beta RII system may be responsible for growth suppression. To explore this possibility, we determined several characteristics essential for the autocrine system. We found that HCT116 + ch3 expresses wild-type as well as mutated TGF-beta RII mRNA. In addition, phosphorylation of TGF-beta RI and growth inhibition were observed in HCT116 + ch3 but not in HCT116 by exposure to exogenous TGF-beta. The amount of TGF-beta1 in HCT116 + ch3 cultures was remarkably less than that in the HCT116, suggesting that TGF-beta produced by HCT116 + ch3 cells may be consumed by the cells. The conditioned medium from HCT116 cultures inhibits HCT116 + ch3 growth. This inhibition was neutralized by the anti-TGF-beta antibody. Taken together, these results strongly suggest that the TGF-beta RII gene defect in HCT116 is complemented by a wild-type gene on the transferred chromosome 3 and that HCT116 + ch3 gained the ability to respond to TGF-beta. Simultaneous complementation of defects of a responsible gene and a major target gene by the chromosome transfer is useful to prove the inactivated phenotypes acquired during colorectal tumorigenesis.

[Identification and location of the toxin protein genes in 56 Bacillus thuringiensis isolates]

Polymerase chain reaction was performed to screen Bacillus thuringiensis isolates for cryI, cryIII, and cryV genes with cryI-, cryIII-, and cryV-specific primers respectively. The results indicated that, in the 56 Bt isolates examined, 7 isolates contain cryI gene, 2 isolates contain cryIII gene, and 21 isolates contain both cryI and cryV genes. The cryV gene was located by Southern hybridization in the large plasmid of about 150 MD molecular mass.

Insight into the catalytic mechanism of DNA polymerase beta: structures of intermediate complexes

The catalytic reaction mediated by DNA polymerases is known to require two Mg(II) ions, one associated with dNTP binding and the other involved in metal ion catalysis of the chemical step. Here we report a functional intermediate structure of a DNA polymerase with only one metal ion bound, the DNA polymerase beta-DNA template-primer-chromium(III).2'-deoxythymidine 5'-beta,gamma-methylenetriphosphate [Cr(III).dTMPPCP] complex, at 2.6 A resolution. The complex is distinct from the structures of other polymerase-DNA-ddNTP complexes in that the 3'-terminus of the primer has a free hydroxyl group. Hence, this structure represents a fully functional intermediate state. Support for this contention is provided by the observation of turnover in biochemical assays of crystallized protein as well as from the determination that soaking Pol beta crystals with Mn(II) ions leads to formation of the product complex, Pol beta-DNA-Cr(III).PCP, whose structure is also reported. An important feature of both structures is that the fingers subdomain is closed, similar to structures of other ternary complexes in which both metal ion sites are occupied. These results suggest that closing of the fingers subdomain is induced specifically by binding of the metal-dNTP complex prior to binding of the catalytic Mg(2+) ion. This has led us to reevaluate our previous evidence regarding the existence of a rate-limiting conformational change in Pol beta's reaction pathway. The results of stopped-flow studies suggest that there is no detectable rate-limiting conformational change step.

Regulation of an endogenous locus using a panel of designed zinc finger proteins targeted to accessible chromatin regions. Activation of vascular endothelial growth factor A

We have mapped conserved regions of enhanced DNase I accessibility within the endogenous chromosomal locus of vascular endothelial growth factor A (VEGF-A). Synthetic zinc finger protein (ZFP) transcription factors were designed to target DNA sequences contained within the DNase I-hypersensitive regions. These ZFPs, when fused to either VP16 or p65 transcriptional activation domains, were able to activate expression of the VEGF-A gene as assayed by mRNA accumulation and VEGF-A protein secretion through a range exceeding that induced by hypoxic stress. Importantly, multiple splice variants of VEGF-A mRNA with defined physiological functions were induced by a single engineered ZFP transcription factor. We present evidence for an enhanced activation of VEGF-A gene transcription by ZFP transcription factors fused to VP16 and p65 targeted to two distinct chromosomal sites >500 base pairs upstream or downstream of the transcription start site. Our strategy provides a novel approach for dissecting the requirements for gene regulation at a distance without altering the DNA sequence of the endogenous target locus.

Cloning, characterization, and chromosomal mapping of a human electroneutral Na(+)-driven Cl-HCO3 exchanger

The electroneutral Na(+)-driven Cl-HCO3 exchanger is a key mechanism for regulating intracellular pH (pH(i)) in neurons, glia, and other cells. Here we report the cloning, tissue distribution, chromosomal location, and functional characterization of the cDNA of such a transporter (NDCBE1) from human brain (GenBank accession number AF069512). NDCBE1, which encodes 1044 amino acids, is 34% identical to the mammalian anion exchanger (AE2); approximately 50% to the electrogenic Na/HCO3 cotransporter (NBCe1) from salamander, rat, and humans; approximately 73% to mammalian electroneutral Na/HCO3 cotransporters (NBCn1); 71% to mouse NCBE; and 47% to a Na(+)-driven anion exchanger (NDAE1) from Drosophila. Northern blot analysis of NDCBE1 shows a robust approximately 12-kilobase signal in all major regions of human brain and in testis, and weaker signals in kidney and ovary. This human gene (SLC4A8) maps to chromosome 12q13. When expressed in Xenopus oocytes and running in the forward direction, NDCBE1 is electroneutral and mediates increases in both pH(i) and [Na(+)](i) (monitored with microelectrodes) that require HCO3(-) and are blocked by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). The pH(i) increase also requires extracellular Na(+). The Na(+):HCO3(-) stoichiometry is 1:2. Forward-running NDCBE1 mediates a 36Cl efflux that requires extracellular Na(+) and HCO3(-) and is blocked by DIDS. Running in reverse, NDCBE1 requires extracellular Cl(-). Thus, NDCBE1 encodes a human, electroneutral Na(+)-driven Cl-HCO3 exchanger.

Method of improving optical poling efficiency in polymer films

The alignment of dye molecules in optically poled polymer films is modeled. We point out that when writing beams (fundamental and second harmonic) are linearly polarized with their polarization directions parallel, the majority of the dye molecules in a poled film are axially oriented perpendicular to the writing-beam polarization, whereas the minority are polar oriented parallel to the writing-beam polarization. Only the latter, however, contribute to the second-order nonlinearity of the film. This model is verified by experiments. Based on the model, a new method of improving optical poling efficiency is put forward.

Expression, purification and biochemical characterization of a recombinant phospholipase A2, with anticoagulant activity from Agkistrodon halys Pallas

A cloned cDNA encoding a PLA2 from Agkistrodon halys Pallas was found to have conservative residues Glu53 and Trp70 but with Lys56 and Lys67 substituted by Thr56 and Asp67, respectively, when compared with sequences of other class II PLA2 with anticoagulant activity. It was inserted into a temperature-sensitive bacterial expression vector and effectively expressed in Escherichia coli RR1. The protein was produced as insoluble inclusion bodies and recovered by centrifugation after enzyme digestion. By washing to partial purification, the expression product was refolded and was purified by FPLC superose 12 to appear as a single band in SDS-PAGE. The recombinant protein proved to have obvious enzymatic, anticoagulant and hemolytic activities, which were removed after modification by p-BPB. These findings suggest that the pharmacological activities of this recombinant PLA2 may be related to its catalytic activity and warrant further research on the structure-function relationships of the pharmacological site of the PLA2 from Agkistrodon halys Pallas.

An alternatively spliced long form of Fas apoptosis inhibitory molecule (FAIM) with tissue-specific expression in the brain

The gene encoding Fas apoptosis inhibitory molecule (FAIM) was cloned by differential display using RNA obtained from Fas-resistant and Fas-sensitive primary murine B lymphocytes. FAIM is highly evolutionarily conserved and broadly expressed, suggesting that its gene product plays a key role in cellular physiology. Here we report the identification of a new, longer form of FAIM (FAIM-L) and characterization of the genomic locus that clarifies its origin. The murine FAIM gene is located at chromosome 9f1, a region syntenic to the corresponding location of the human FAIM gene. The gene consists of six exons and contains putative translation initiation sites within exons II and III. The long form of FAIM is generated by all six exons, whereas the originally cloned form of FAIM, now termed FAIM-Short (FAIM-S) is generated from five exons by alternative splicing. FAIM-L is dominantly expressed in the brain whereas FAIM-S is widely expressed in many tissues.

DNA polymerase beta: contributions of template-positioning and dNTP triphosphate-binding residues to catalysis and fidelity

The specific catalytic roles of two groups of DNA polymerase beta active site residues identified from crystal structures were investigated: residues possibly involved in DNA template positioning (Lys280, Asn294, and Glu295) and residues possibly involved in binding the triphosphate moiety of the incoming dNTP (Arg149, Ser180, Arg183, and Ser188). Eight site-specific mutants were constructed: K280A, N294A, N294Q, E295A, R149A, S180A, R183A, and S188A. Two-dimensional NMR analysis was employed to show that the global conformation of the mutants has not been perturbed significantly. Pre-steady-state kinetic analyses with single-nucleotide gapped DNA substrates were then performed to obtain the rate of catalysis at saturating dNTP (k(pol)), the apparent dissociation constant for dNTP (K(d)), catalytic efficiency k(pol)/K(d), and fidelity. Of the three template-positioning residues, Asn294 and Glu295 (but not Lys280) contribute significantly to k(pol). Taken together with other data, the results suggest that these two residues help to stabilize the transition state during catalysis even though they interact with the DNA template backbone rather than directly with the incoming dNTP or the opposite base on the template. Furthermore, the fidelity increases by up to 19-fold for N294Q due to differential k(pol) effects between correct and incorrect nucleotides. Of the four potential triphosphate-binding residues, Ser180 and Arg183 contribute significantly to k(pol) while the effects of R149A are relatively small and are primarily on K(d), and Ser188 appears to play a minimal role in the catalysis by Pol beta. These results identify several residues important for catalysis and quantitate the contributions of each of those residues. The functional data are discussed in relation to the prediction on the basis of available crystal structures.

[Application of cellulose acetate membrane with the technique of impression cytology combined with immunohistochemical staining for detection of dry eye]

PURPOSE

To evaluate the conjunctival cells by impression cytology with cellulose acetate membrane.

METHODS

The expression of the TGF-beta 1 in conjunctival epithelium of 24 patients with dry eye were studied by impression cytology combined with immunohistochemical staining and observed by microscope.

RESULT

The cellulose acetate membrane is very transparent under the microscope. Cell's membrane by TGF-beta 1 staining is clear, cytoplasm brown and nuclei blue.

CONCLUSION

The method of impression cytology with cellulose acetate membrane is simple and has no injury to the ocular surface. Combined with immunohistochemistry staining, it is suitable to observe the conjunctival cells by this technique which has an important value for the examination of the ocular surface disease.

[Laboratory study on protective and therapeutic effects of pinacidil on pulmonary vascular remodeling in rats with hypoxia-induced pulmonary hypertension]

OBJECTIVE

To investigate the protective and therapeutic effects of pinacidil on hypoxia-induced pulmonary hypertension(HPH) and pulmonary vascular remodeling.

METHODS

46 male Wister rats were divided into control group, hypoxic group and treated group (hypoxic rat treated with pinacidil for 4 weeks). Rat models with chronic HPH were established by chronic hypobaric hypoxia [(10 +/- 0.5)% O2, 4 weeks)]. The mean pulmonary arterial pressure (mPAP) and right ventricle/left ventricle and septum [RV/(LV + S)] were measured and the small pulmonary arterial morphologic changes were observed with morphmetric analysis under microscopes in three groups.

RESULTS

(1) The level of mPAP(28.4 +/- 2.8) mm Hg and RV/(LV + S) (0.30 +/- 0.03) were significantly higher in the hypoxic group than (16.2 +/- 1.8) mm Hg and (0.22 +/- 0.03) in control group respectively (P < 0.01). Morphometry investigation showed that the external diameter became smaller and that ratio of vascular wall thickness to external diameter (MT%) (25.7 +/- 2.6)% and ratio of vascular wall area to total area (MA%) (75.3 +/- 5.6)% significantly increased in the hypoxic group. (2) The mPAP(23.3 +/- 2.6) mm Hg, RV/(LV + S) (0.27 +/- 0.04) and pulmonary vascular pathologic changes MT%(22.1 +/- 2.5)% and MA% (67.0 +/- 6.1)% significantly decreased in the treated group, indicating that pinacidil inhibited HPH and hypoxia-induced thickening and muscularization of small pulmonary arteria.

CONCLUSION

Pinacidil may partly prevent the development of HPH and pulmonary vascular remodeling.

Regulation of yeast ectoapyrase ynd1p activity by activator subunit Vma13p of vacuolar H+-ATPase

CD39-like ectoapyrases are involved in protein and lipid glycosylation in the Golgi lumen of Saccharomyces cerevisiae. By using a two-hybrid screen, we found that an activator subunit (Vma13p) of yeast vacuolar H(+)-ATPase (V-ATPase) binds to the cytoplasmic domain of Ynd1p, a yeast ectoapyrase. Interaction of Ynd1p with Vma13p was demonstrated by direct binding and co-immunoprecipitation. Surprisingly, the membrane-bound ADPase activity of Ynd1p in a vma13Delta mutant was drastically increased compared with that of Ynd1p in VMA13 cells. A similar increase in the apyrase activity of Ynd1p was found in a vma1Delta mutant, in which the catalytic subunit A of V-ATPase is missing, and the membrane peripheral subunits including Vma13p are dissociated from the membranes. However, the E286Q mutant of VMA1, which assembles inactive V-ATPase complex including Vma13p in the membrane, retained wild type levels of Ynd1p activity, demonstrating that the presence of Vma13p rather than the function of V-ATPase in the membrane represses Ynd1p activity. These results suggest that association of Vma13p with the cytoplasmic domain of Ynd1p regulates its apyrase activity in the Golgi lumen.

[A clinical analysis of combination treatment with brachytherapy and external radiation, plus chemotherapy for the treatment of esophageal cancer]

OBJECTIVE

To analyse the value of various combinations of treatment for esophageal cancer.

METHODS

One hundred twenty cases of esophageal cancer were randomly divided into four groups, 30 cases in each group. Group I was treated with external radiation (RT) alone; group II, with RT plus brachytherapy; group III with RT plus chemotherapy, and group IV with RT plus brachytherapy and chemotherapy. RT with 60Co was given 2 Gy daily, 5 times a week, with a total dose of 60-74 Gy. Brachytherapy was given 6-8 Gy once weekly with a total dose of 18-24 Gy. Chemotherapy with carboplatin was given 100 mg/day, five days a week at first and fifth week.

RESULTS

The 1, 2, 3-year survival rate in group II, III and IV was higher than that in group I (P < 0.05). The 3-year survival rate of group I-IV patients was 13.3%, 36.7%, 40.0%, 46.7%, respectively. More patients died of cancer recurrence and progression in group I than in any of the other 3 groups of patients (P < 0.05). However, the frequency of distant metastasis was not significantly different.

CONCLUSION

The combination treatment with external radiation, brachytherapy and chemotherapy can improve the local control of tumor growth and the survival rate in esophageal cancer patients.

Expression of nerve growth factor from Agkistrodon halys Pallas in E. coli and its purification

The nerve growth factor (NGF) gene of Agkistrodon halys Pallas was cloned into a secretive prokaryotic expression vector pET-22b+ which carried a C-terminal His. Tag sequence. After transforming into E. coli BL21 (DE3), NGF was induced to express at 30 degrees C by IPTG. SDS-PAGE analysis showed an induced expression product band which constituted about 20% of the total bacterial proteins. However, its molecular weight was larger than what was expected. Moreover, the analysis of product solubility revealed that NGF was in the form of inclusion bodies. The inclusion bodies were solubilized in 6 mumol/L guanidine HCl and purified directly by immobilized metal (Ni2+) chelation affinity chromatography. The product was renatured by dilution and air oxidation in the presence of 5 mumol/L CuSO4, and was proved active by examining the survival rate of PC12 cells in a serum-free medium.

Receptor-specific regulation of B-cell susceptibility to Fas-mediated apoptosis and a novel Fas apoptosis inhibitory molecule

The susceptibility of primary B cells to Fas (APO-1, CD95)-mediated apoptosis is modulated by signals derived from additional surface receptors: CD40 engagement produces upregulation of Fas expression and marked sensitivity to Fas-induced cell death, whereas antigen receptor engagement, or interleukin-4 receptor (IL-4R) engagement, inhibits Fas killing and thereby produces Fas resistance, even in otherwise susceptible, CD40-stimulated targets. Surface immunoglobulin (sIg) and IL-4R utilize distinct signaling pathways to produce Fas resistance that rely on protein kinase C and signal transducer and activator of transcription 6, respectively sIg signaling for inducible Fas resistance requires nuclear factor-kappaB and depends on new macromolecular synthesis. Proximate mediators for Fas resistance include the known anti-apoptotic gene products Bcl-xL and FLIP (but not Btk), and a novel anti-apoptotic gene that encodes Fas apoptosis inhibitory molecule (FAIM). FAIM was identified by differential display and was cloned as two alternatively spliced forms: FAIM-S is broadly expressed, whereas faim-L expression is tissue specific. faim is highly evolutionarily conserved, suggesting an important function throughout phylogeny. Inducible resistance to Fas-mediated apoptosis is speculated to protect antigen-specific B cells during potentially dangerous interactions with FasL-bearing T cells; the elevated sIg-signaling threshold for inducible Fas resistance in autoreactive, tolerant B cells would insure against autoimmunity. However, aberrant acquisition of Fas resistance may allow autoreactive B cells to escape Fas deletion and malignant lymphocytes to thwart antitumor immunity.

Computer based analyses of the 5'-flanking regions of selected genes involved in the nucleotide excision repair complex

We have previously observed that the mRNA of selected genes involved in nucleotide excision repair appear to be coordinately expressed in human tissues from patients with ovarian cancer, testicular cancer, malignant brain tumors, and other malignancies. Such genes include ERCC1, XPA, XPB, XPD, XPF, and XPG. Coordinate mRNA expression appears to be most impressive in non-malignant tissues. We therefore began to explore possible reasons why such coordinate expression should occur. DNA sequences for the above noted genes were obtained from GeneBank. Two different software programs were applied to the DNA sequence, to the area 5' to the start of exon I of each gene. Analyses were performed by computer. The length of the 5' area assessed, was based on previous reports that determined what portion of the genomic sequence comprised the 5' UTR of the promoter of the respective gene. Based on this approach, potential DNA binding sites for no less than three dozen proteins, were identified in the 5'-flanking region of each of the NER genes studied. For each gene, potential binding sites for activator proteins and for repressor proteins were identified. The 5'-flanking regions for each gene noted above, had binding sites in common for 14 proteins with transcription modulatory activity. Eleven of these proteins are known for activator activity; two are reported to have repressor activity, and one has both repressor and activator function. These data suggest a possible molecular basis for the previously observed coordinate mRNA expression of selected NER genes in human tissue specimens.

[Clinical study on Zhuyu Xiaozhong mixture combined with stereotaxic drainage in treating hypertensive cerebral hemorrhage]

OBJECTIVE

To explore the effective method of integrated traditional Chinese and western medicine (TCM-WM) therapy in treating hypertensive cerebral hemorrhage (HCH).

METHODS

Sixty-one HCH patients were randomly divided into two groups: the treated group (group A, 31 cases) and the control group (group B, 30 cases), the former group was treated with stereotaxic drainage and orally taken Zhuyu Xiaozhong mixture (ZYXZM), and the latter group with stereotaxic drainage alone.

RESULTS

The total effective rate of group A was 83.9%, significantly higher than that of group B (60.0%, P < 0.05). In comparing the two groups, the neurological function recovery, the quality of life and the hematoma absorption in group A were significantly better than those of group B (P < 0.05).

CONCLUSION

ZYXZM combined with stereotaxic drainage is effective in treating HCH. It could promote the neurological function recovery and improve the quality of life as well.

[Study on whole blood photoacoustic spectroscopy for PIH (pregnancy-induced hypertension)]

The whole blood of the normal pregnancy and PIH were checked by photoacoustic spectroscopy device. The results shows that there is a characteristic peak in 630-650 nm of the PIH. The characteristic peak may provide an important basis diagnosis of PIH. Basing the result on this, the author makes a further study on the characteristic peak by adding different anticoagulant into blood. The results show that the EDTA is the best one for the characteristic peak analysis.

The role of Sp1 in the differential expression of transforming growth factor-beta receptor type II in human breast adenocarcinoma MCF-7 cells

Progression of MCF-7 cells from early passage (MCF-7E, <200 passage) to late passage (MCF-7L, >500 passage) correlates with a loss of sensitivity to exogenous TGFbeta1. We have previously shown that loss of TGFbeta sensitivity is due to decreased expression of the transforming growth factor receptor type II (TbetaRII) and is associated with increased tumorigenicity in nude mice. Reduced TbetaRII expression in MCF-7L cells is caused by decreased TbetaRII promoter activity in this cell line. Our previous studies using 5' deletion constructs of this promoter revealed that MCF-7L cells were unable to support transcription of the minimal promoter (-47 to +2) to the same levels as the MCF-7E cells. This region of the promoter contains an Sp1 element at position -25 from the major transcription start site. In this study, we investigated the role of Sp1 in TbetaRII transcription. Mutation of the Sp1 site resulted in decreased transcription of TbetaRII in MCF-7E and MCF-7L cells, indicating that this site played a role in transcription of this promoter. Gel shift assays using the proximal Sp1 site from the TbetaRII promoter showed enhanced DNA:protein complex formation with nuclear proteins isolated from MCF-7E cells compared with MCF-7L cells. Supershift analysis identified this binding activity as Sp1. Western blot analysis of Sp1 levels demonstrated that MCF-7E cells contain increased Sp1 protein compared with MCF-7L cells, paralleling the increased binding activity. Differential Sp1 activity was also demonstrated by higher levels of transcription of an Sp1-dependent insulin-like growth factor II promoter construct in MCF-7E cells compared with MCF-7L cells. Co-transfection of an Sp1 expression vector with a TbetaRII promoter construct in MCF-7L cells induced the expression from the promoter-CAT constructs and resulted in an increase of endogenous TbetaRII protein levels. These results demonstrate that the transcriptional repression of TbetaRII in MCF-7L cells is caused, in part, by lower Sp1 levels.

[GC-MS analysis of volatile componments in root of Ficus hitra]

The volatile components in root of Ficus hitra Vahl were analyzed by GC-MS, the results suggested that the main volatile components in root of Ficus hitra Vahl were Hexadecanoic acid, Oleic acid, Linolic acid and Ethyl Acetate; its ether extract contains Isopsoralen and Bergapten. Coumarins should be one of the effective sections in root of Ficus hitra Vahl.

Various AGC repeat numbers in the coding region of the human transcription factor gene E2F-4

The E2F family of transcription factors regulates the expression of genes required for DNA synthesis and cell cycle control. The AGC triplet repeat in the coding region of the E2F-4 gene, a member of the family, has been reported to be mutated in colorectal cancers with a microsatellite instability (MSI) phenotype. We found a wider range variation of the repeat number in DNAs from tumors, the corresponding normal mucosa, and healthy individuals. A total of 5 repeat variants, ranging from 8 to 17 AGC repeats, was detected in 6 (9.7%) of the 62 healthy individuals and 8 (8.9%) of the 90 normal DNAs of the patients. The wild-type 13 repeat was present in all of these individuals. The variation of the AGC repeat number may be a polymorphism. Further, loss of heterozygosity (LOH) at the E2F-4 locus in the tumor tissues of 2 (25%) of the 8 informative cases was detected. The variation may be a useful marker for detection of LOH in primary tumors.

[Observation of the endothelial healing in rabbit corneal alkali wounds by alizarin red S-trypan blue staining method]

PURPOSE

To study the healing of the corneal endothelial cells in rabbit corneal alkali wounds.

METHODS

26 New Zealand white rabbits were used. A alkali wound was created with a round filter paper, 8 mm in diameter, which was soaked in 0.5 N NaOH for 5 seconds and was placed centrally on the cornea for 60 seconds. The rabbits were killed in 20 minutes; 1, 2, 6, 12 h; 1, 2, 3, 5, 7, 10, 14, 30 days after injury. The corneal endothelium was examined in the light microscope using a lizarin red S-trypan blue staining method.

RESULTS

Twenty minutes after the wound, the corneal endothelial cells were destroyed. 72 hours following the wound, the endothelial cells surrounding the burns became larger, irregular and started to migrate onto the denuded descemet's membrane. The endothelial cells covered the burn with the spindle-shaped cells 7 days after wound.

CONCLUSION

The endothelial damage is healed by the division and migration of remaining endothelial cells at the margin of the wound, which has some characters of fibroblast.

A yeast Golgi E-type ATPase with an unusual membrane topology

E-type ATPases are involved in many biological processes such as modulation of neural cell activity, prevention of intravascular thrombosis, and protein glycosylation. In this study, we show that a gene of Saccharomyces cerevisiae, identified by similarity to that of animal ectoapyrase CD39, codes for a new member of the E-type ATPase family (Apy1p). Overexpression of Apy1p in yeast cells causes an increase in intracellular membrane-bound nucleoside di- and triphosphate hydrolase activity. The activity is highest with ADP as substrate and is stimulated similarly by Ca (2+), Mg(2+), and Mn(2+). The results also indicate that Apy1p is an integral membrane protein located predominantly in the Golgi compartment. Sequence analysis reveals that Apy1p contains one large NH(2)-terminal hydrophilic apyrase domain, one COOH-terminal hydrophilic domain, and two hydrophobic stretches in the central region of the polypeptide. Although no signal sequence is found at the NH(2)-terminal portion of the protein and no NH(2)-terminal cleavage of the protein is observed, demonstrated by the detection of NH(2)-terminal tagged Apy1p, the NH(2)-terminal domain of Apylp is on the luminal side of the Golgi apparatus, and the COOH-terminal hydrophilic domain binds to the cytoplasmic face of the Golgi membrane. The second hydrophobic stretch of Apy1p is the transmembrane domain. These results indicate that Apylp is a type III transmembrane protein; however, the size of the Apy1p extracytoplasmic NH(2) terminus is much larger than those of other type III transmembrane proteins, suggesting that a novel translocation mechanism is utilized.

[TLC-identification of radix Rehmanniae and its mixed medicinal materials in Pharmacopoeia]

In 237 kinds of medicinal meterials included 71 kinds of Chinese patent medicines composed in Pharmacopoeia such as Liuweidihuang Pills, character identify constituent of Radix Rehmanniae was found by TLC, and was successed to use to identification of Radix Rehmanniae in 10 kinds of Chinese patent medicines such as Liuweidihuang Pills.

A common polymorphism in exon 40 of the human mannose 6-phosphate/insulin-like growth factor II receptor gene

Mammalian mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF2R) binds insulin-like growth factor II and ligands containing an M6P recognition marker like the latent transforming growth factor-beta. Its genetic alteration has been associated with tumorigenesis of various tumours. We report here a novel polymorphism in exon 40 of the human M6P/IGF2R gene (6206A-->G, Asn2020Ser). The G allele frequency was 0.347 in Japanese. Observed heterozygosity was 0.468. The polymorphism may be useful for studying loss of heterozygosity in primary tumours and gene imprinting.

Differentiation of embryonic stem cells into neurons and retina-like structure in nude mice

PURPOSE

To investigate the intraocular growth and biological characteristics of mice embryonic stem cells in nude mice.

METHODS

Murine embryonic stem cells (D3 cell line) were cultured and maintained in an undifferentiated state in vitro, then transplanted into the anterior chamber of nude mice. Mophological and immunohistochemical examinations were implemented.

RESULTS

Two to three days after transplantation, yellow-white floating granules, sheets and masses were seen inside the anterior chamber and vitreous cavity, and enlarged gradually. 14-20 days later, the mice were executed. Morphological examination showed that there were undifferentiated cells and some round or polygonal differentiated cells in anterior chamber and vitreous cavity. The morphology of these differentiated cells were similar to that of the retina. The cells were highly positive in NSE staining.

CONCLUSION

The transplanted embryonic stem cells could grow in the eyes of nude mice with tendency to differentiate into neurons and retina-like structure.

[Rapid detection of an HPFH deletion by PCR amplification with three primers bridging the breakpoint]

OBJECTIVE

To establish a rapid and reliable PCR method for detecting a deletional hereditary persistence of fetal hemoglobin (HPFH) found in Chinese.

METHODS

Based on some novel DNA sequences across the 3'breakpoint of a HPFH deletion observed in our laboratory, we designed a PCR amplification with three primers bridging the breakpoint. In this system, oligonucleotide primers have been chosen which allow specific identification of both normal and deletional chromosomes under identical condition in either the same or parallel PCR reactions.

RESULTS

The expected two specific amplification bands were produced; one was 565bp in length and stood for the normal alleles,the other,37bp in length represented the mutant alleles of beta-globin gene cluster. This duplex system could directly genotype DNA samples bearing this type of HPFH deletion.

CONCLUSION

This rapid and inexpensive method could be used as a routine method in the molecular screening of carriers and for the prenatal diagnosis of this disease.

cDNA copies of the testis-specific lactate dehydrogenase (LDH-C) mRNA are present in spermatogenic cells in mice, but processed pseudogenes are not derived from mRNAs that are expressed in haploid and late meiotic spermatogenic cells

Retroposons are a class of genes created by reverse transcribing a processed mRNA and inserting the DNA copy into genomic DNA in germ-line cells. The present study concerns the question: Are retroposons created in meiotic and haploid spermatogenic cells? We demonstrate that polymerase chain reaction amplifies cytoplasmic DNAs with the expected intronless-structure of endogenous reverse transcriptase copies of the processed lactate dehydrogenase C mRNA encoding the testis-specific isoform of lactate dehydrogenase. Quantification of cytoplasmic LDH-C mRNA and endogenous cDNA by competitive RT-PCR and PCR, respectively, indicates that the level of LDH-C cDNA is lower by a factor of about 10(7) than the level of LDH-C mRNA in the cytoplasmic nucleic acids extracted from the testes of 14-day-old mice, and that about 1 in 10(5) meiotic cells contains an endogenous cDNA copy of LDH-C mRNA. A review of the literature reveals that a large number of genes including the LDH-C gene, whose expression is restricted to spermatogenic cells, are always single copy. Collectively, these observations suggest that reverse transcriptase cDNA copies of mRNAs are present in meiotic and haploid spermatogenic cells, but these cDNAs are not integrated into genomic DNA.

Non-radioactive hybridization in microwells using enzyme linked immune sorbent assay for detection of RT-PCR-amplified CK19- and CEA-mRNA

PCR enzyme linked immune sorbent assay (ELISA) was developed for detection of RT-PCR-amplified cytokeratin 19 (CK19) mRNA and carcinoembryonic antigen (CEA) mRNA. The non-radioactive hybridization was performed in a streptavidin-coated microwell with digoxigenin-labeled PCR products and with biotin-labeled capture probe. PCR ELISA was proved to be expedient, simple, sensitive and safe for identification of CK19-, CEA-RT-PCR products. These results were proven by sequencing.

[Significance of detecting E-selectin of serum and pleural effusion in differentiating benign and malignant diseases]

OBJECTIVE

To evaluate the significance of detecting E-selectin of serum and pleural effusion in differentiating benign and malignant diseases.

METHOD

E-selectin of serum and pleural effusion in 23 patients with tuberculous pleurisy and 21 patients with lung cancer involving pleura was detected by ELISA method.

RESULT

E-selectin of serum(44 +/- 5 micrograms/L) and pleural effusion (24 +/- 3 micrograms/L) in patients with tuberculous pleurisy was much higher than that of serum (27 +/- 4 micrograms/L) and pleural effusion (11 +/- 3 micrograms/L) in lung cancer patients (P < 0.01). In addition, E-selection of serum in patients with tuberculous pleurisy was also much higher than that of pleural effusion (P < 0.01). And there was no correlation between E-selectin of serum and that of pleural effusion in patients with tuberculous pleurisy (r = 0.16, P > 0.05).

CONCLUSION

E-selectin of serum and pleural effusion in patients with tuberculous pleurisy is produced from different sources. And E-selectin in patients with tuberculous pleurisy is much higher than those with lung cancer. Thence detecting E-selectin of serum and pleural effusion might be helpful for differentiating benign and malignant diseases.

DNA polymerase beta: effects of gapped DNA substrates on dNTP specificity, fidelity, processivity and conformational changes

Pre-steady-state kinetic analysis was used to compare the catalytic properties of DNA polymerase beta (Pol beta) for single-base gap-filling and regular duplex DNA synthesis. The rate of polymerization (kpol) and the apparent equilibrium dissociation constant of dNTP (Kd) were determined with single-nucleotide gapped DNA substrates for all four possible correct base pairs and twelve possible incorrect base pairs, and the results were compared with those obtained previously with non-gapped primer/template duplex DNA substrates. For correct dNTP incorporation, the use of single-nucleotide gapped DNA led to significant decreases in the Kd of dNTP. Although kpol was little affected, the catalytic efficiency kpol/Kd increased significantly owing to the decreases in Kd. In contrast, for incorrect dNTP incorporation, the use of single-nucleotide gapped DNA substrates did not affect the Kd of dNTP appreciably but caused the kpol (and thus kpol/Kd) for incorrect dNTP incorporation to increase. As a consequence the fidelity of Pol beta was not significantly affected by the use of single-nucleotide gapped DNA substrates. In addition we show that under processive polymerization conditions the processivity of Pol beta increases in the gap-filling synthesis owing to a decreased rate of DNA dissociation. Finally, with a single-nucleotide gapped DNA substrate the rate-limiting conformational change step before chemistry was also observed. However, the preceding fast conformational change observed with duplex DNA substrates was not clearly detected. A possible cause is that in the complex with the gapped DNA, the 8 kDa N-terminal domain of Pol beta already exists in a closed conformation. This interpretation was supported by tryptic digestion experiments.

Cytotoxicity of contact lens care solution to human corneal epithelium in vitro

PURPOSE

To investigate the cytotoxicity of soft contact lens multi-purpose care solutions which are now in common use in China.

METHODS

The cell culture method was used. Cytotoxicity was indicated by significant increases in the number of dead cells relative to controls.

RESULTS

Cells were exposed to soft contact lens care solutions for 15 min. They were irregular in shape and variable in size. The intercellular space increased and variable in size. The intercellular space increased and the cells became scrunken. With the time of exposure elongated, damage of cells became more severe.

CONCLUSIONS

Four kinds of soft contact lens multi-purpose care solutions may have harmful effects on the culture of human corneal epithelial cells. Soaked lenses should be rinsed with saline before being placed in the eyes in order to reduce the potential toxicity of contact lens care solutions.

When an ATPase is not an ATPase: at low temperatures the C-terminal domain of the ABC transporter CvaB is a GTPase

The ATP-binding cassette (ABC) transporters belong to a large superfamily of proteins which share a common function and a common nucleotide-binding domain. The CvaB protein from Escherichia coli is a member of the bacterial ABC exporter subfamily and is essential for the export of the peptide antibiotic colicin V. Here we report that, surprisingly, the CvaB carboxyl-terminal nucleotide-binding domain (BCTD) can be preferentially cross-linked to GTP but not to ATP at low temperatures. The cross-linking is Mg2+ and Mn2+ dependent. However, BCTD possesses similar GTPase and ATPase activities at 37 degrees C, with the same kinetic parameters and with similar responses to inhibitors. Moreover, a point mutation (D654H) in CvaB that completely abolishes colicin V secretion severely impairs both GTPase and ATPase activities in the corresponding BCTD, indicating that the two activities are from the same enzyme. Interestingly, hydrolysis activity of ATP is much more cold sensitive than that of GTP: BCTD possesses mainly GTP hydrolysis activity at 10 degrees C, consistent with the cross-linking results. These findings suggest a novel mechanism for an ABC protein-mediated transport with specificity for GTP hydrolysis.

[Effect of keratinocyte growth factor on corneal epithelial wound healing]

OBJECTIVE

To select effective methods for accelerating corneal epithelial wound healing and treating persistent corneal epithelial defect.

METHODS

Exogenous keratinocyte growth factor (KGF, 0.1 ng/ml - 100 ng/ml) was added to cultures of human corneal epithelial cells and DNA synthesis in corneal epithelial cells was measured with [(3)H]-thymidine incorporation and liquid scintillation techniques. The effective concentration of topical application of KGF was calculated and 1 microg/ml KGF was then applied topically to rabbit eyes. Corneal epithelial defect was measured by a digital computer at different times.

RESULTS

KGF at a dosage ranging from 1 ng/ml to 100 ng/ml enhanced cellular proliferation effectively (the rate of cell proliferation 27.66% - 76.73%) and in a dose-dependent manner (r = 0.9233, P < 0.001). Topical application of KGF significantly accelerated corneal wound healing in rabbits (Epithelial healing rate in the KGF-treated group was 1.77 +/- 0.23 mm(2)/h, while in the PBS-treated group it was 1.49 +/- 0.24 mm(2)/h; P < 0.05).

CONCLUSION

The results suggest that exogenous KGF stimulate proliferation of human corneal epithelial cells and accelerate corneal epithelial wound healing in vivo.

[The combined procedure of limbal transplantation (LT) and penetrating keratoplasty (PK) for severe ocular obsolete chemical or thermal burns]

PURPOSE

To improve the prognosis of grafts for obsolete ocular chemical or thermal burns.

METHODS

LT + PK or PK were performed in 28 eyes with severe chemical or thermal burns. The effects of the two groups were compared.

RESULTS

In LT + PK group(12 eyes), during 5 to 28 months of follow-up, the results showed improved visual acuity in 9 eyes (75%), maintained stable epithelial adhesion without recurrent erosion or persistent epithelial defect in 11 eyes (91.67%), graft transparent in 9 eyes (75%). Nine eyes (75%) showed prevented neovascularization and conjunctival tissue from growing into graft. Allograft rejection were identified in 4 eyes (33.33%). In routine PK group (16 eyes), during 3 to 22 months of follow-up, the results showed improved visual acuity in 4 eyes (25%), maintained stable epithelial adhesion without recurrent erosion or PCED in 8 eyes (50%), graft transparent in 4 eyes (25%). Four eyes (25%) showed prevented neovascularization and conjunctival tissue from growing into cornea.

CONCLUSIONS

Combined procedure of LT and PK is an effective treatment for severe ocular chemical or thermal burns. It can reduce persistent corneal epithelial defect and prevent neovascularization and conjunctival epithelial from growing into cornea thus maintaining graft transparent and improving visual acuity.

Interactions of dedicated export membrane proteins of the colicin V secretion system: CvaA, a member of the membrane fusion protein family, interacts with CvaB and TolC

The antibacterial peptide toxin colicin V uses a dedicated signal sequence-independent system for its secretion in Escherichia coli and requires the products of three genes, cvaA, cvaB, and tolC. As a member of the membrane fusion protein family, CvaA is supposed to form a bridge that connects the inner and outer membranes via interaction with CvaB and TolC, respectively. In this study, we investigated the possible interaction of these proteins. When CvaA or CvaB was absent, the corresponding amount of CvaB or CvaA, respectively, was decreased, and the amounts of both proteins were reduced when TolC was depleted. Translational lacZ fusions showed that TolC did not affect the synthesis of either CvaA-beta-galactosidase or CvaB-beta-galactosidase, and CvaA or CvaB did not affect the synthesis of CvaB-beta-galactosidase or CvaA-beta-galactosidase, respectively. However, the stabilities of CvaA and CvaB proteins were affected by the absence of one another and by that of TolC. The instability of CvaA was more severe in TolC-depleted cells than in CvaB-depleted cells. On the other hand, CvaB was less stable in the absence of CvaA than in the absence of TolC. In addition, using a cross-linking reagent, we showed that CvaA directly interacts with both CvaB and TolC proteins. Taken together, these data support the hypothesized structural role of CvaA in connecting CvaB and TolC.

DNA polymerase beta: multiple conformational changes in the mechanism of catalysis

Stopped-flow fluorescence assay was applied to identify conformational changes in the catalytic cycle of DNA polymerase beta (Pol beta), using a synthetic DNA primer/template containing 2-aminopurine (2-AP) at the template position opposite the incoming dNTP. Two phases of fluorescence change were observed in the stopped-flow fluorescence assay of the incorporation of the correct nucleotide dTTP. The rate of the slow phase corresponds to that of product formation. This slow phase was identified as the result of a rate-limiting conformational change step before chemistry because this slow phase was also observed with a dideoxynucleotide at the 3' end of the primer which prevents chemical bond formation. The fast phase was also attributed to a conformational change step since its dependence on [dTTP] is hyperbolic. The rates of the two phases and their dependence on [dTTP] and [Mg2+] suggest that the fast conformational change is induced by the binding of MgdNTP and the slow conformational change is induced by the binding of the catalytic Mg2+ ion. The same biphasic kinetics with different rates were also observed with the thio analog dTTPalphaS and incorrect nucleotides dATP, dGTP, and dCTP. The structural nature for the two conformational changes has been discussed in relation to the available structural information of this enzyme. The results could help to explain how a polymerase controls and achieves its fidelity with a multiple conformational change mechanism.

[A study on the mechanism of damage to DNA in rats by ethylene oxide]

DNA in the liver, kidney, testes, etc. was amplified with semi-random polymerase chain reaction (PCR) in Wistar male rats exposed to ethylene oxide (EtO) for various times and in control rats with hemoglobin gene-specific primer to study the damage effects of EtO on DNA molecule. Results showed that inhalation of 800 mg/m3 of EtO for six to nine weeks could cause damage to DNA in the liver, kidney and testes, etc. to various extent, with the most serious damage to DNA in the testes.

[Culture of human corneal epithelial cells]

PURPOSE

To select culture technique of human epithelial cells for grafts.

METHODS

Epithelial cells of limbus were collected by improved enzymatic disaggregation or explant technique growth curves and to calculate doubling time. DNA synthesis of cells were measured with 3H-thymidine incorporation and liquid scintillation techniques.

RESULTS

Doubling time of cells which were collected by enzymatic disaggregation and by explant technique were 54.15 +/- 4.28 h and 67.88 +/- 1.96 h (P < 0.01). Cellular DNA synthesis of the former was more active (P < 0.01).

CONCLUSIONS

Epithelial cells which were collected by improved enzymatic disaggregation from limbus include stem cells of corneal epithelium. These cells show more active cellulde proliferation and are fitter for use as grafts.

[Effects of ethylene oxide on activity of DNA methylase in rats]

Male Wistar rats were exposed to ethylene Oxide (Eto) via inhalation at a concentration of 751.7 mg/m3 two hours a day and six days a week for nine consecutive weeks. Sensitivity test of restriction enzymes Mbo I, Sau3A I, Hpa II and Msp I and Southern blot were conducted to study the effects of ethylene oxide on activity of major intracellular modification enzyme, DNA methylase. Results showed that DNA in liver, kidney and testis of rats were completely enzymolysed and only one blot was seen after being treated with Hind III, Mbo I and Sau3A I, and incompletely enzymolysed and multiple blots were seen after being treated with Hpa II and Msp I. There were no significant differences in electrophoresis pattern, number of blots and intensity of radioautograph between the exposed animals and controls. It indicated that no effects of Eto on activity of DNA methylase in the liver, kidney and testis of rats was found, and degree of methylation in the testis was much less than that in the liver and kidney.

DNA polymerase beta: analysis of the contributions of tyrosine-271 and asparagine-279 to substrate specificity and fidelity of DNA replication by pre-steady-state kinetics

DNA polymerase beta (pol beta) from rat brain, overexpressed in Escherichia coli, was used as a model to study the factors responsible for substrate specificity [kpol, Kd(app) and kpol/Kd(app)] and fidelity during DNA synthesis. The roles of two active-site residues, Asn-279 and Tyr-271, were examined by construction of N279A, N279Q, Y271A, Y271F and Y271S mutants followed by structural analyses by NMR and CD and functional analyses by pre-steady-state kinetics. The results are summarized as follows. (i) None of the two-dimensional NMR spectra of the mutants was significantly perturbed relative to that for wild-type pol beta, suggesting that Tyr-271 and Asn-279 are not important for the global structure of the protein. (ii) CD analyses of guanidinium hydrochloride-induced denaturation showed that all mutants behaved similarly to the wild type in the free energy of denaturation, suggesting that Tyr-271 and Asn-279 are not critical for the conformational stability of pol beta. (iii) The Kd(app) for the correct dNTP was lower than that for the incorrect dNTP by a factor of 10-30 in the case of wild-type pol beta. Upon mutation to give N279A and N279Q, the Kd(app) for the correct dNTP increased by a factor of 15-25. As a consequence, the Kd(app) values for the correct and incorrect nucleotides were similar for N279A and N279Q, suggesting that the main function of the side chain of Asn-279 is in discrimination between the binding of correct and incorrect dNTPs. (iv) In the case of the Y271A mutant, the fidelity and the catalytic efficiency kpol/Kd(app) were little perturbed relative to the wild type. However, both the kpol and Kd(app) values for dNTP were 4-8 times lower in the case of the Y271A mutant than the corresponding values for wild-type pol beta. Since the chemical step may not be rate-limiting for wild-type pol beta, the effect on kpol could be quite significant if it is caused by a perturbation in the chemical step. (v) Pol beta displayed the greatest specificity towards the G:C base pair, which is incorporated during base excision repair of G:U and G:T mispairs. This specificity was slightly enhanced for the Y271F mutant.

[A clinical analysis of 30 cases of sympathetic ophthalmia]

PURPOSE

To study the clinical characteristics of 30 patients with sympathetic ophthalmia in order to find out the valuable clues for future investigation.

METHODS

The incidence, cause, location of injury, and prognosis of the 30 patients were analyzed retrospectively.

RESULTS

Patients with sympathetic ophthalmia occupied 0.72% of the in-patients with eye trauma in our hospital between 1982 and 1997. In most cases the disease related with perforating injury at the limbus or the sclera, but in a few cases it may be associated with blunt trauma, tumors or even intraocular operation. Diffuse uveitis in sympathizing eye happened in 63.3% of the patients.

CONCLUSION

Development of sympathetic ophthalmia always related to the damaged ocular structure. Association of sympathetic ophthalmia with hereditary background and the melanin-protein may be worthy of study in future.

Processing of colicin V-1, a secretable marker protein of a bacterial ATP binding cassette export system, requires membrane integrity, energy, and cytosolic factors

Extracellular secretion of the peptide antibiotic colicin V (ColV) in Escherichia coli is mediated by a dedicated exporter system consisting of host TolC protein and the products of two specific genes, cvaA and cvaB, the latter being a member of the ATP binding cassette (ABC) superfamily. An amino-terminal export signal of ColV is specific for the CvaA-CvaB-TolC exporter and is processed concomitant with secretion. In this study, we attempt to characterize this processing with a secretable marker protein, ColV-1, using a newly developed in vitro assay. Processing is found to be dependent on both CvaA-CvaB transporters and the TolC protein and to require membrane integrity. An additional cytoplasmic soluble factor(s) is also necessary for the processing. Although the sequence of the cleavage site suggests it could be a substrate, ColV-1 cannot be processed in vitro by the purified leader peptidase I. Moreover, ColV-1 processing is inhibited by antipain and N-ethylmaleimide. Furthermore, the processing requires energy in the form of nucleotide hydrolysis. These results indicate that the processing of ColV-1 is specific and more complex than expected, requiring the CvaA-CvaB-TolC transporter intact in the membrane, energy, and cytosolic factors for rapid cleavage.

Study on ultrastructural cytochemistry and pathogenic mechanism of Trichomonas vaginalis

OBJECTIVE

To study the relation among enzymic ultrastructural localizations, cell organelles and functions of Trichomonas vaginalis (T. vaginalis) as well as its pathogenic mechanism.

MATERIAL AND METHODS

The specimens were Trichomonas vaginalis cultured purely for several generations. After prefixation, several electron microscopic cytochemical reactions for marker enzymes of lysosome, Golgi body, mitochondrion and microbody as well as Ur-Pb-Cu impregnation were undertaken. Then the specimens were post-fixed and embedded, and the unstained ultrathin sections were observed under a transmission electron microscope.

RESULTS

The activities of acid phosphatase and cytidine monophosphatase appeared in the primary and secondary lysosomes of the parasite, and the reaction product of peroxidase was found in the secondary lysosomes. It was found that lysosomes could release hydrolytic enzymes out of the cell. The reaction products of thiamine pyrophosphatase and nicotinamide adenine dinucleotide phosphatase were located within the mature-surface and intermediate saccules of Golgi body respectively. The reactions for succinate dehydrogenase, cytochrome oxidase and catalase were negative. The hydrogenosomes, endoplasmic reticulum and Golgi bodies of the parasite were densely stained by Ur-Pb-Cu impregnation method.

CONCLUSIONS

T.vaginalis has lysosomal system which can release hydrolases out of the parasite, causing damage to the vaginal and urethral epithelial cells. This may be an important pathogenic mechanism of vaginitis and urethritis caused by T.vaginalis. This protozoon has well-developed Golgi bodies and rich endoplasmic reticulum. It lacks mitochondrion and microbody, but has abundant hydrogenosomes which are energy producing organelles of anaerobic metabolism and resemble microbody in morphology and mitochondrion in some functions.

[Experimental study of circulatory dynamics following inhalation injury in dogs]

Early changes in respiratory and circulatory dynamics before and after steam-inhalation injury were made in a dog model were studied. The results showed that the resistance of the respiratory system was significantly higher 3 hours and 4 hours post injury than that before injury (P < 0.05), the compliances of both the lung 4 hours post-injury and the respiratory system 3 hours psot-injury significantly decreased (P < 0.05), and the heart rate markedly lowered (P < 0.01), and the cardiac output also decreased (P < 0.05) 2 hours after injury. It is suggested that the early changes in the respiratory and circulatory dynamics may be used as markers for the diagnosis and treatment of the inhalation injury.

DNA polymerase beta: pre-steady-state kinetic analysis and roles of arginine-283 in catalysis and fidelity

DNA polymerase beta (pol beta) is the smallest and least complex DNA polymerase. The structure of the enzyme is well understood, but little is known about its catalytic properties, particularly processivity and fidelity. Pre-steady-state analysis of the incorporation of a single nucleotide into a short 25/45 oligonucleotide primer-template by pol beta was used to define the kinetic parameters of the polymerase. In addition, nucleotide analogs and site-specific mutants, along with structural analyses, were used to probe the structure-function relationship of pol beta. Several significant findings have been obtained: (i) The catalysis by pol beta is processive and displays an initial burst under pre-steady-state conditions, but the processivity is poor compared to other polymerases. (ii) The fidelity of pol beta is also low relative to other polymerases. (iii) Under pre-steady-state conditions the chemical step appears to be only partially rate-limiting on the basis of the low thio effect (4.3), defined as kpol(dNTP)/kpol(dNTP alpha S). The thio effect increases to 9 for incorporation of an incorrect nucleotide. These results are consistent with the existence of a substrate-induced conformational change that is also partially rate-limiting. (iv) A comparison between the two-dimensional NMR spectra of the wild-type and mutant enzymes indicates that the mutations at position 283 did not significantly perturb the structure of the enzyme. The conformational stability of the mutants is also unperturbed. Thus, R283 is not important to the overall structure of the enzyme. (v) The results of kinetic analyses of R283A and R283K mutants indicate that the hydrogen bond between R283 of pol beta and the template is important for catalysis. Both R283A and R283K mutants displayed decreases in catalytic efficiency by a factor of ca. 200 relative to wild-type pol beta. The mutants are also less faithful by a factor of 2-4, in terms of the T-G mispair vs the T-A correct pair. The perturbation, however, could occur at both the implied conformational step and the chemical step, since the thio effects of the mutants for both correct and incorrect nucleotides are similar to those of WT pol beta.