[The apoptosis-inducing activity of human selenoprotein P shorter isoform]

OBJECTIVE

Human selenoprotein P (HSelP) is unique protein that contains 10 selenocysteines encoded by 10 inframe UGA, which typically function as stop codon. The function of HSelP remains unclear, in part due to the inability to express it by gene recombinant technique. This study is to investigate expression and purification of recombinant HSelP in prokaryotic expression system, and its activity to induce apoptosis in vitro.

METHODS

The shorter HSelP isoform was cloned. After the selenocysteine (SeCys) at 40th position from N terminus of the HSelP shorter isoform was mutated into cysteine by PCR, it was expressed in E. coli. The expressed product was purified with DEAE column and identified by Western blot. Subsequently, its function on induction of mitochondrial apoptotic activity was studied.

RESULTS

The mutant HSelP shorter isoform expressed in prokaryotic system was purified by DEAE column to 90% homogeneity. The purified product, HSelP280m, induced the opening of mitochondrial permeability transition pore (PTP) and decreased the transmembrane potential in a dose-dependent manner. These events could be abolished by PTP specific inhibitors.

CONCLUSION

HSelP280m can induce the opening of mitochondrial PTP, which provides a basis for investigating the structure and function of recombinant HSelP.

Complete genome sequences of the SARS-CoV: the BJ Group (Isolates BJ01-BJ04)

Beijing has been one of the epicenters attacked most severely by the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) since the first patient was diagnosed in one of the city's hospitals. We now report complete genome sequences of the BJ Group, including four isolates (Isolates BJ01, BJ02, BJ03, and BJ04) of the SARS-CoV. It is remarkable that all members of the BJ Group share a common haplotype, consisting of seven loci that differentiate the group from other isolates published to date. Among 42 substitutions uniquely identified from the BJ group, 32 are non-synonymous changes at the amino acid level. Rooted phylogenetic trees, proposed on the basis of haplotypes and other sequence variations of SARS-CoV isolates from Canada, USA, Singapore, and China, gave rise to different paradigms but positioned the BJ Group, together with the newly discovered GD01 (GD-Ins29) in the same clade, followed by the H-U Group (from Hong Kong to USA) and the H-T Group (from Hong Kong to Toronto), leaving the SP Group (Singapore) more distant. This result appears to suggest a possible transmission path from Guangdong to Beijing/Hong Kong, then to other countries and regions.

[Cloning and expression of simplex herpes virus ? US4 fragment]

BACKGROUND

To get early laboratory study of type specific antigenicity of herpes simplex virus II.

METHODS

PCR and prokaryotic expression technique.

RESULTS

Herpes simplex virus II type specific gene fragment was expressed in E.coli and the products can be used as specific antigen for the detection of anti\HSV in the recovery sera.

CONCLUSIONS

Cloning and express of HSVII type specific antigen found the basis for developing specific diagnosis methods and vaccine of HSV.

[Expression of thermal stable, soluble hepatitis E virus recombinant antigen]

BACKGROUND

To obtain thermal stable, soluble, biologically active hepatitis E virus recombinant antigen using thioredoxin fusion expression system.

METHODS

HEV ORF2 gene fragment (6964-7126 nt) was inserted into thioredoxin fusion expression vector pThioHisA. The recombinant plasmid was transformed into E. coli BL21 strain. After induction with IPTG, cells were lysed and the supernatant was subjected to 80 degree treatment for 10 minutes. After centrifugation, the supernatant was tested by ELISA.

RESULTS

SDS-PAGE analysis showed the thioredoxin. HEV fusion protein was highly expressed and was thermally stable, soluble. HEV specific ELISA confirmed this fusion protein possessing HEV specific antigenicity.

CONCLUSIONS

Using thioredoxin fusion expression system, a soluble, thermal stable, biologically active HEV recombinant antigen was successfully expressed.

Caspase 3-cleaved N-terminal fragments of wild-type and mutant huntingtin are present in normal and Huntington's disease brains, associate with membranes, and undergo calpain-dependent proteolysis

The Huntington's disease (HD) mutation is a polyglutamine expansion in the N-terminal region of huntingtin (N-htt). How neurons die in HD is unclear. Mutant N-htt aggregates in neurons in the HD brain; expression of mutant N-htt in vitro causes cell death. Other in vitro studies show that proteolysis by caspase 3 could be important in regulating mutant N-htt function, but there has been no direct evidence for caspase 3-cleaved N-htt fragments in brain. Here, we show that N-htt fragments consistent with the size produced by caspase 3 cleavage in vitro are resident in the cortex, striatum, and cerebellum of normal and adult onset HD brain and are similar in size to the fragments seen after exogenous expression of human huntingtin in mouse clonal striatal neurons. HD brain extracts treated with active caspase 3 had increased levels of N-htt fragments. Compared with the full-length huntingtin, the caspase 3-cleaved N-htt fragments, especially the mutant fragment, preferentially segregated with the membrane fraction. Partial proteolysis of the human caspase 3-cleaved N-htt fragment by calpain occurred in vitro and resulted in smaller N-terminal products; products of similar size appeared when mouse brain protein extracts were treated with calpain. Results support the idea that sequential proteolysis by caspase 3 and calpain may regulate huntingtin function at membranes and produce N-terminal mutant fragments that aggregate and cause cellular dysfunction in HD.

Regeneration of hyaline cartilage by cell-mediated gene therapy using transforming growth factor beta 1-producing fibroblasts

Transforming growth factor beta (TGF-beta) has been considered as a candidate for gene therapy of orthopedic diseases. The possible application of cell-mediated TGF-beta gene therapy as a new treatment regimen for degenerative arthritis was investigated. In this study, fibroblasts expressing active TGF-beta 1 were injected into the knee joints of rabbits with artificially made cartilage defects to evaluate the feasibility of this therapy for orthopedic diseases. Two to 3 weeks after the injection there was evidence of cartilage regeneration, and at 4 to 6 weeks the cartilage defect was completely filled with newly grown hyaline cartilage. Histological analyses of the regenerated cartilage suggested that it was well integrated with the adjacent normal cartilage at the sides of the defect and that the newly formed tissue was indeed hyaline cartilage. Our findings suggest that cell-mediated TGF-beta 1 gene therapy may be a novel treatment for orthopedic diseases in which hyaline cartilage damage has occurred.

Pathological, ultrastructural and immunohistochemical observations of adenoma of retinal pigment epithelium

PURPOSE

To Study the clinical, pathological, ultrastructural and immunohistchemical characters of adenoma of the retinal pigment epithelium in order to offer evidence to diagnose this tumor.

METHODS

Routine paraffin slices HE stain, histochemistry PAS and VG stain, transmission electron microscopy, and immunohistochemistry for S-100 and vimentin with LSAB method were used.

RESULTS

The tumor cells were oval and cuboidal in shape. Part of the tumor had a tubular arrangement. Around the sheets of tumors cells there was a large amount of uniform red stick-like substances. The above matter represented positive in PAS stain. Most of the above matter was yellow, while less of the matter showed red in VG stain. Transmission electron microscopy showed that there were tight junctions between tumor cells. Immunohistochemistry showed positive for S-100, negative for vimentin.

CONCLUSIONS

The ultrastructural and immunohistochemical characters of the adenoma of retinal pigment epithelium are consistent with the retinal pigment epithelium.

Human immunodeficiency virus type 1 IIIB selected for replication in vivo exhibits increased envelope glycoproteins in virions without alteration in coreceptor usage: separation of in vivo replication from macrophage tropism

Analysis of viral replication and pathogenicity after in vivo selection of human immunodeficiency virus type 1 (HIV-1) attenuated in vitro will help to define the functions involved in replication and pathogenesis in vivo. Using the SCID-hu Thy/Liv mouse and human fetal thymus organ culture as in vivo models, we previously defined HIV-1 env determinants (HXB2/LW) which were reverted for replication in vivo (L. Su et al., Virology 227:46-52, 1997). In this study, we examined the replication of four highly related HIV-1 clones directly derived from Lai/IIIB or after selection in vivo to investigate the envelope gp120 determinants associated with replication in macrophages and in the thymus models in vivo. The LW/C clone derived from the IIIB-infected laboratory worker and HXB2/LW both efficiently infected monocyte-derived macrophages (MDM) and the human thymus. Although the laboratory worker (LW) isolates showed altered tropism from IIIB, they still predominantly used CXCR4 as coreceptors for infecting peripheral blood mononuclear cells, macrophages, and the thymus. Interestingly, a single amino acid mutation in the V3 loop associated with resistance to neutralizing antibodies was also essential for the replication activity of the LW virus in the thymus models but not for its activity in infecting MDM. The LW virions were equally sensitive to a CXCR4 antagonist. We further demonstrated that the LW HIV-1 isolate selected in vivo produced more infectious viral particles that contained higher levels of the Env protein gp120. Thus, selection of the laboratory-attenuated Lai/IIIB isolate in vivo leads to altered tropism but not coreceptor usage of the virus. The acquired replication activity in vivo is correlated with an early A-to-T mutation in the V3 loop and increased virion association of HIV-1 Env gp120, but it is genetically separable from the acquired replication activity in macrophages.

Concordant utilization of macrophage entry coreceptors by related variants within an HIV type 1 primary isolate viral swarm

There is considerable diversity among HIV-1 strains in terms of their ability to use entry coreceptors on macrophages, especially CXCR4, but it is not known whether virus-specific differences exist among related members of a viral swarm. Defining how entry coreceptors on primary target cells are utilized by the spectrum of HIV-1 variants that emerge in vivo is important for understanding the relationship between coreceptor selectivity and pathogenesis. HIV-1 89.6(PI) is a dual-tropic primary isolate, and the prototype 89.6-cloned R5X4 Env uses both CXCR4 and CCR5 on macrophages. We generated a panel of env clones from the 89.6(PI) quasispecies and found a mixture of R5, R5X4, and X4 variants on the basis of fusion and infection of coreceptor-transfected cell lines. Here we address the use of macrophage coreceptors by these related Envs by analyzing fusion and infection of primary monocyte-derived macrophages mediated specifically through each coreceptor. All R5X4 Envs utilized both CXCR4 and CCR5 on macrophages, while R5 variants used CCR5 only. One variant characterized in cell lines as X4 used both CXCR4 and CCR5 on macrophages. No Env variant fused with macrophages through alternative coreceptor pathways. Thus, there was heterogeneity in coreceptor use among the related Env variants, but use of each coreceptor specifically in macrophages was consistent among members of the viral swarm. Coreceptor use in transfected cells generally predicted use in primary macrophages, although for some Envs macrophages may be a more sensitive indicator of CCR5 use than transfected cell lines.

A CCR5/CXCR4-independent coreceptor pathway on human macrophages supports efficient SIV env-mediated fusion but not infection: implications for alternative pathways of viral entry

Several coreceptors in addition to CCR5 and CXCR4 support immunodeficiency virus entry in transfected cells, but whether they could play a role in HIV-1 pathogenesis is uncertain. To probe whether human macrophages express potentially functional alternative entry pathways, we analyzed cell-cell fusion and infection of primary macrophage by several SIVmac Envs. All Envs fused with normal macrophages. One, SIVmac316, also fused efficiently with macrophages lacking CCR5. CCR5-independent fusion was not mediated by CXCR4 and was CD4 dependent, while CCR5-mediated fusion was partly independent of CD4. However, pseudotype virions carrying the SIVmac316 Env and HIV-1 core could not infect macrophages through the CCR5-independent pathway, although they did infect wild-type macrophages. Thus, human macrophages possess an alternative coreceptor pathway that mediates SIV Env fusion but does not support infection. Macrophage entry pathways other than CCR5 and CXCR4 may have limited potential in pathogenesis given their restricted capacity for infection despite efficient fusion.

[Application of dhfr gene negative Chinese hamster ovary cell line to express hepatitis B virus surface antigen]

OBJECTIVE

To set up an efficient expressing system for recombinant hepatitis B virus surface antigen (HBsAg) in dhfr gene negative CHO cell line.

METHODS

HBsAg gene expressing plasmid pCI-dhfr-S was constructed by integrating HBsAg gene into plasmid pCI which carries dhfr gene. The HBsAg expressing cell line was set up by transfection of plasmid pCI-dhfr-S into dhfr gene negative CHO cell line in the way of lipofectin.

RESULTS

Under the selective pressure of MTX, 18 of 28 clonized cell lines expressed HBsAg, 4 of them reached a high titer of 1:32 and protein content 1-3 micrograms/ml.

CONCLUSION

In this study, the high level expression of HBsAg demonstrated that the dhfr negative mammalian cell line when recombined with plasmid harboring the corresponding deleted gene can efficiently express the foreign gene. The further steps toward building optimum conditions of the expressing system and the increase of expressed product are under study.

[Study on the dynamic changes of retinoblastoma gene of SO-Rb50 cell line]

PURPOSE

To study the dynamic changes of Retinoblastoma Gene of SO-Rb50 cell line.

METHODS

1) Southern blot hybridization was used to analyse the tumor cell DNA of 327th passage of SO-Rb50 cell line. 2) A promoter and 27 exons of Rb gene were screened exon-by-exon by using PCR-SSCP at 415th and 713th passages of SO-Rb50 cell line. 3) Three cell cloning strains named as MC2, MC3 and MC4 were isolated by single cell cloning technique from the SO-Rb50-775, and mutation of Rb gene were also screened exon-by-exon by using PCR-SSCP-HA in MC2-11, MC3-11, MC4-11 and MC3-138.

RESULTS

The 3.5 Kb, 2.9 Kb and 1.0 Kb bands were deleted in the DNA of SO-Rb50-327 tumor cells, showing the deletion of Rb gene in SO-Rb50 cell line. Exon23 of 451th passage cells decreased one band; but exon 25 of 713th passage cells decreased two bands, indicating that exon 25 had new mutation. PCR-SSCP-HA analysis of exon24 showed that MC4-11 and MC3-138 had abnormal bands, but MC2-11 and MC3-11 weren't found mutation of Rb gene. This result suggested that new mutation occurred to exon24 of MC3 during a long-term culture in vitro.

CONCLUSION

Retinoblastoma gene mutation of SO-Rb50 cell line had dynamic changes during a long-term culture.

Substance P antagonist (CP-96,345) inhibits HIV-1 replication in human mononuclear phagocytes

Substance P (SP) is a potent modulator of neuroimmunoregulation. We recently reported that human immune cells express SP and its receptor. We have now investigated the possible role that SP and its receptor plays in HIV infection of human mononuclear phagocytes. SP enhanced HIV replication in human blood-isolated mononuclear phagocytes, whereas the nonpeptide SP antagonist (CP-96,345) potently inhibited HIV infectivity of these cells in a concentration-dependent fashion. CP-96,345 prevented the formation of typical giant syncytia induced by HIV Bal strain replication in these cells. This inhibitory effect of CP-96,345 was because of the antagonism of neurokinin-1 receptor, a primary SP receptor. Both CP-96,345 and anti-SP antibody inhibited SP-enhanced HIV replication in monocyte-derived macrophages (MDM). Among HIV strains tested (both prototype and primary isolates), only the R5 strains (Bal, ADA, BL-6, and CSF-6) that use the CCR5 coreceptor for entry into MDM were significantly inhibited by CP-96,345; in contrast, the X4 strain (UG024), which uses CXCR4 as its coreceptor, was not inhibited. In addition, the M-tropic ADA (CCR5-dependent)-pseudotyped HIV infection of MDM was markedly inhibited by CP-96,345, whereas murine leukemia virus-pseudotyped HIV was not affected, indicating that the major effect of CP-96,345 is regulated by Env-determined early events in HIV infection of MDM. CP-96,345 significantly down-regulated CCR5 expression in MDM at both protein and mRNA levels. Thus, SP-neurokinin-1 receptor interaction may play an important role in the regulation of CCR5 expression in MDM, affecting the R5 HIV strain infection of MDM.

Coreceptor choice and T cell depletion by R5, X4, and R5X4 HIV-1 variants in CCR5-deficient (CCR5delta32) and normal human lymphoid tissue

Coreceptor utilization by HIV-1 is an important determinant of pathogenesis. However, coreceptor selectivity is defined in vitro, while in vivo critical pathogenic events occur in lymphoid tissues. Using pharmacological inhibitors, we recently provided evidence that coreceptor selectivity by the R5X4 dual-tropic isolate 89.6 was more restricted in ex vivo infected lymphoid tissue than in vitro [S. Glushakova, Y. Yi, J. C. Grivel, A. Singh, D. Schols, E. De Clercq, R. G. Collman, and L. Margolis (1999). J. Clin. Invest. 104, R7-R11]. Here we extend those observations using CCR5-deficient (CCR5Delta32) lymphoid tissue as well as additional primary isolates. We definitively show that neither CCR5 nor secondary coreceptors used in vitro mediate 89.6 infection in lymphoid tissue. We also demonstrate that restricted coreceptor use in lymphoid tissue ex vivo compared with in vitro utilization occurs with other dual-tropic primary isolates and is not unique to 89.6. For all strains tested that are dual tropic in vitro, severe CD4 T cell depletion in lymphoid tissue correlated with preferential CXCR4 use in this ex vivo system.

The hepatitis B virus encoded oncoprotein pX amplifies TGF-beta family signaling through direct interaction with Smad4: potential mechanism of hepatitis B virus-induced liver fibrosis

Hepatitis B, one of the most common infectious diseases in the world, is closely associated with acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Many clinical investigations have revealed that hepatic fibrosis is an important component of these liver diseases caused by chronic hepatitis B. TGF-beta signaling plays an important role in the pathogenesis of fibrosis in chronic hepatitis and cirrhosis. As these diseases are associated with hepatitis B virus (HBV) infection, we examined the possibility that the HBV-encoded pX oncoprotein regulates TGF-beta signaling. We show that pX enhances transcriptional activity in response to TGF-beta, BMP-2, and activin by stabilizing the complex of Smad4 with components of the basic transcriptional machinery. Additionally, confocal microscopic studies suggest that pX facilitates and potentiates the nuclear translocation of Smads, further enhancing TGF-beta signaling. Our studies suggest a new paradigm for amplification of Smad-mediated signaling by an oncoprotein and suggest that enhanced Smad-mediated signaling may contribute to HBV-associated liver fibrosis.

Mechanism of induction of transforming growth factor-beta type II receptor gene expression by v-Src in murine myeloid cells

Transforming growth factor (TGF)-beta1 plays an important role during hematopoiesis. Previously, we had shown that the growth of a v-Src-transformed myeloid cell line was markedly more inhibited by TGF-beta treatment when compared with the wild-type myeloid cell line. To investigate the increased growth sensitivity of the v-Src-transformed myeloid cell line, 32D-src, to TGF-beta, we examined expression of the TGF-beta type II receptor (TGF-beta RII) gene in myeloid cell lines. Northem blot analysis showed that expression of approximately 8- and 6-kb species of TGF-beta RII transcripts was markedly increased in the 32D-src cell line. The expression of the TGF-beta RII promoter linked to a reporter gene was increased 23-fold by v-Src. DNA transfection and electrophoretic mobility shift assay revealed that v-Src induces TGF-beta RII promoter activity through an AP1/ATF2-like sequence (-219 to -172), ETS binding sites (+1 to +36), and the inverted CCAAT box (-81 to -77). Novel DNA-protein complexes with ETS binding sites are significantly increased in v-src-transformed cell lines compared with the control cell line. These results suggest that v-Src induces activity of the TGF-beta RII promoter through multiple elements by inducing expression of nuclear proteins interacting with these elements.

Regulatory defects in Cbl and mitogen-activated protein kinase (extracellular signal-related kinase) pathways cause persistent hyperexpression of CD40 ligand in human lupus T cells

To identify intrinsic defects in lupus, we studied short-term, CD4(+) T cell lines that were established from 16 lupus patients (active or inactive) and 15 normal subjects by stimulating once with anti-CD3, anti-CD28, and IL-2. After resting, the pure CD4(+) T cells were exposed to anergy-inducing stimulation with plate-bound anti-CD3 mAb in the absence of APC. Lupus T cells showed prolonged high level expression of CD40 ligand (CD40L, CD154) even in the face of anergy protocol, which shut down CD40L expression in normal T cells. The sustained CD40L expression in lupus T cells did not correlate with memory status or Th deviation, and was relatively independent of IL-2 or other autocrine or paracrine signals via CD28 or CTLA-4. Cyclosporin A could block CD40L expression by lupus T cells when added early during the anti-CD3 stimulation period, but only partially when added later, indicating that another mechanism regulates the prolonged hyperexpression of CD40L besides the Ca(2+) --> calcineurin-dependent NF-AT pathway. When exposed to the anergy protocol, lupus T cells, in marked contrast to normal T cells, did not phosphorylate Cbl/Cbl-b but continued to express strongly phosphorylated extracellular signal-regulated kinase (ERK); U0126, a specific inhibitor of mitogen-activated protein kinase kinase --> ERK, could block both the early and the prolonged hyperexpression of CD40L. Thus, pathways regulating the activities of Cbl and one particular mitogen-activated protein kinase, ERK, are involved in the prolonged hyperexpression of CD40L in lupus T cells.

A novel mitochondrial septin-like protein, ARTS, mediates apoptosis dependent on its P-loop motif

Here we describe a protein product of the human septin H5/PNUTL2/CDCrel2b gene, which we call ARTS (for apoptosis-related protein in the TGF-beta signalling pathway). ARTS is expressed in many cells and acts to enhance cell death induced by TGF-beta or, to a lesser extent, by other apoptotic agents. Unlike related septin gene products, ARTS is localized to mitochondria and translocates to the nucleus when apoptosis occurs. Mutation of the P-loop of ARTS abrogates its competence to activate caspase 3 and to induce apoptosis. Taken together, these observations expand the functional attributes of septins previously described as having roles in cytokinesis and cellular morphogenesis.

[Cell cycle G2 arrest, cell death and nuclear localization induced by human immunodeficiency virus type 1 protein R (VPR) in cervical cancer cells]

OBJECTIVE

To explore the possibility of using Vpr as a biological agent for anticancer therapy.

METHODS

A HIV-1 wild type Vpr and a mutant VprX gene were expressed and tested in a cervical cancer HeLa cell line. The ability of Vpr to induce cell cycle G2 arrest and cell death was measured by flow cytometric analysis. Nuclear localization of Vpr was visualized by fluorescent light emitted from the green fluorescent protein (GFP) -Vpr fusion protein.

RESULTS

Consistent with early reports, Vpr, not VprX, induced G2 arrest. However, both Vpr and VprX were able to induce cell death in HeLa cells. We also demonstrated that the nuclear localization of Vpr could be determined by using a GFP-Vpr fusion protein.

CONCLUSIONS

This is the first report documenting in mammalian cells that G2 arrest and cell death induced by Vpr are two independent functions. The unique biological properties of Vpr shown in cervical cancer cells suggest that Vpr may be a useful biological agent for anti -cancer therapy.

Chemokine signaling and HIV-1 fusion mediated by macrophage CXCR4: implications for target cell tropism

To better understand CXCR4 function on macrophages and the relationship between coreceptor use and macrophage tropism among diverse HIV-1 isolates, we analyzed macrophage pathways involved in Env-mediated fusion, productive HIV-1 infection, and chemokine-elicited signaling. We found that both CXCR4 and CCR5 transduced intracellular signals in monocyte-derived macrophages, activating K+ and Cl- ion channels and elevating intracellular calcium in response to their chemokine ligands stromal cell-derived factor-1alpha and macrophage inflammatory protein-1beta, respectively. The prototype T-tropic X4 strain IIIB infected macrophages poorly, and this was associated with failure of the IIIB Env to fuse efficiently with target macrophages despite functional CXCR4. In contrast, several primary X4 isolates mediated efficient CXCR4-dependent fusion and productive macrophage infection. Several R5X4 strains could fuse with and infect macrophages through both CCR5 and CXCR4. Thus, macrophages express functional CXCR4 and CCR5 but primary and prototype X4 isolates differ in their ability to utilize macrophage CXCR4. Isolates classified as X4 based on coreceptor use may be phenotypically either T-tropic or dual-tropic and, conversely, phenotypically dual-tropic isolates may be either R5X4 or X4 based on coreceptor use.

Co-receptor usage was more predictive than NSI/SI phenotype for HIV replication in macrophages: is NSI/SI phenotyping sufficient?

A monocyte-derived macrophage (MDM) culture assay was used to define the replication kinetics of HIV isolates. Ten-day-old MDMs were infected with HIV. Supernatants were collected and assayed for HIV p24 on days 3, 7, 10, and 14 post-infection (PI). In this assay, SF162 (macrophage tropic, NSI) produced increasing amounts of HIV p24 antigen with increasing time in culture. BRU (nonmacrophage tropic, SI) infection resulted in low levels of HIV p24 antigen with no increase in production during the culture period. A panel of 12 clinical isolates was evaluated. All isolates produced detectable levels of HIV p24 antigen in MDMs. However, the NSI viruses had significantly higher log10 HIV p24 antigen values at all times PI (P < 0.01). Co-receptor usage was determined for all 12 isolates (8 NSI and 4 SI). All SI isolates used CXCR4 for entry; two used CXCR4 only, one used CXCR4, CCR5, and CCR3, and one was a mixture of two isolates using CXCR4 and CCR5. None of the NSI viruses used CXCR4 for entry. All used CCR5 as their predominant co-receptor. Of the eight NSI isolates, three used CCR5 only, two used CCR5 and CCR2b, one used CCR5 and CCR3, and one used CCR5, CCR3, and CCR2b. Log10 HIV p24 antigen production on day 14 PI for viruses that used CCR5+CCR3 (3.79 + 1.40) was greater than for viruses that used CCR5+CCR2b (3.22 + 1.55) or CCR5 (3.32 + 1.49), and all were greater than those that used CXCR4 only (1.69 + 0.28), regardless of SI phenotype (P < 0.05). Thus, in these primary isolates, macrophage tropism and replication kinetics were closely linked to CCR5 utilization, whereas SI capacity was closely linked to CXCR4 utilization. Furthermore, viruses, which could use CCR5 and CCR3 for entry, had a replication advantage in macrophages, regardless of SI phenotype.

Neuroprotective activity of tiagabine in a focal embolic model of cerebral ischemia

Gamma aminobutyric acid (GABA) agonists have been shown to have neuroprotective effects when used after focal or global cerebral ischemia. In this study, we evaluated the neuroprotective effects of a GABA re-uptake inhibitory agent, tiagabine, on focal ischemic brain injury in an embolic model in rats. Tiagabine, injected at 1 h after embolization, significantly reduced brain infarction volume, measured with 2,3,5-triphenyltetrazolium chloride (TTC) histological assay. There were varying degrees of neuroprotective effect exhibited in the other experimental groups however this did not reach significance. These results suggest that tiagabine is neuroprotective when administrated at an early period after the ischemic brain injury.

[Study of the distribution feature of the endocrine cells of human islet and its relation to microvasculature]

Double immunohistochemical stain was used for the study of distribution feature of the endocrine cells of human islets and its relation to the microvasculature. The results were as follows (1) Sheath islet was found in human adult islets and the B cells situated the central part of the islets and arrounding it were the A and D cells which formed the sheath of the islets. (2) The identical distribution of the A and D cells was found. (3) Some islets were divided into several "subunite" by connective tissue in which the B cells and A(or D) cells situated the central and peripheral part respectively. (4) The A and D cells were near the microvasculature. These results will provide morphologic basis for the research of the functional relation among the endocrine cells.

Pediatric intractable epilepsy: the role of presurgical evaluation and seizure outcome

Surgical experience with long-term follow-up is limited in childhood intractable epilepsy, compared with adult epilepsy. To assess the role of each presurgical evaluation modality and to identify prognostic factors for favorable seizure control after epilepsy surgery, 38 children with intractable epilepsy who underwent surgery were retrospectively reviewed. Among the available preoperative evaluation modalities, PET and neuropsychological testing showed the highest rates of positive results, whereas MRI was the most concordant with EEG findings. During a follow-up period of at least 12 months, 26 of the 38 patients showed favorable seizure control (Engel classifications I and II). The best seizure control was achieved in patients with a temporal resection and discrete lesion on magnetic resonance imaging. In spite of the invasive study, the less satisfactory results followed an extratemporal resection. We conclude that epilepsy surgery benefits children with intractable epilepsy and that the role of invasive study should be reestablished according to the area of resection and presence of discrete lesion on MRI.

Activin receptor-like kinase 1 modulates transforming growth factor-beta 1 signaling in the regulation of angiogenesis

The activin receptor-like kinase 1 (ALK1) is a type I receptor for transforming growth factor-beta (TGF-beta) family proteins. Expression of ALK1 in blood vessels and mutations of the ALK1 gene in human type II hereditary hemorrhagic telangiectasia patients suggest that ALK1 may have an important role during vascular development. To define the function of ALK1 during development, we inactivated the ALK1 gene in mice by gene targeting. The ALK1 homozygous embryos die at midgestation, exhibiting severe vascular abnormalities characterized by excessive fusion of capillary plexes into cavernous vessels and hyperdilation of large vessels. These vascular defects are associated with enhanced expression of angiogenic factors and proteases and are characterized by deficient differentiation and recruitment of vascular smooth muscle cells. The blood vessel defects in ALK1-deficient mice are reminiscent of mice lacking TGF-beta1, TGF-beta type II receptor (TbetaR-II), or endoglin, suggesting that ALK1 may mediate TGF-beta1 signal in endothelial cells. Consistent with this hypothesis, we demonstrate that ALK1 in endothelial cells binds to TGF-beta1 and TbetaR-II. Furthermore, the ALK1 signaling pathway can inhibit TGF-beta1-dependent transcriptional activation mediated by the known TGF-beta1 type I receptor, ALK5. Taken together, our results suggest that the balance between the ALK1 and ALK5 signaling pathways in endothelial cells plays a crucial role in determining vascular endothelial properties during angiogenesis.

Over-expression of ERT(ESX/ESE-1/ELF3), an ets-related transcription factor, induces endogenous TGF-beta type II receptor expression and restores the TGF-beta signaling pathway in Hs578t human breast cancer cells

The epithelium-specific transcription factor, ERT/ESX/ESE-1/ELF3, binds to the TGF-beta RII promoter in a sequence specific manner and regulates its expression. In this study, we investigated whether ERT could regulate endogenous TGF-beta RII expression in Hs578t breast cancer cells. Analyses of the Hs578t parental cell line revealed low RII mRNA expression and resistance to the growth inhibitory effects of TGF-beta. Infection of this cell line with a retroviral construct expressing ERT induced higher levels of endogenous RII mRNA expression and protein expression relative to cells infected with chloramphenicol acetyltransferase (CATneo) as a control. Relative to control cells, the ERTneo-expressing Hs578t cells show approximately a 50% reduction in cell growth in the presence of exogenous TGF-beta1, as well as a fourfold higher induction of activation in transient transfection assays using the 3TP-luciferase reporter construct. When transplanted into athymic mice, ERT-expressing Hs578t cells showed decreased and delayed tumorigenicity compared with control cells. This data strongly suggests that ERT plays an important role as a transcriptional activator of TGF-beta RII expression, and that deregulated ERT expression may play a critical role in rendering Hs578t human breast cancer cells insensitive to TGF-beta's growth inhibitory effects.

[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.

Changes of nailfold microcirculation in patients of type II diabetes mellitus with diabetic retinopathy

OBJECTIVE

To study the changes of microcirculation in patients with diabetic retinopathy (DR).

METHODS

Examination were performed in 153 cases of type I diabetes mellitus, among them, 72 cases were male, 81 cases were female, mean age 57.0+/-10.0 years, mean disease course 8.2+/-7.5 years. All cases were examined fundi by ophthalmologist, urinary albumin excretion rate (UAE) in 24 hours was measured by radioimmunoassay. Moreover, we examined the blood glucose, blood pressure, blood viscosity and observed the changes of naifold microcirculation.

RESULTS

It was found that there were more evident disturbance of microcirculation, markedly slowed velocity of blood flow (P<0.05), significantly increased aggregation of blood cells (P<0.05) and exudation around the loop (P<0.05) in the group with DR, compared with the group without DR.

CONCLUSION

It was more evident disturbance of nailfold microcirculation in patients with diabetic retinopathy.

Role of CXCR4 in cell-cell fusion and infection of monocyte-derived macrophages by primary human immunodeficiency virus type 1 (HIV-1) strains: two distinct mechanisms of HIV-1 dual tropism

Dual-tropic human immunodeficiency virus type 1 (HIV-1) strains infect both primary macrophages and transformed T-cell lines. Prototype T-cell line-tropic (T-tropic) strains use CXCR4 as their principal entry coreceptor (X4 strains), while macrophagetropic (M-tropic) strains use CCR5 (R5 strains). Prototype dual tropic strains use both coreceptors (R5X4 strains). Recently, CXCR4 expressed on macrophages was found to support infection by certain HIV-1 isolates, including the dual-tropic R5X4 strain 89.6, but not by T-tropic X4 prototypes like 3B. To better understand the cellular basis for dual tropism, we analyzed the macrophage coreceptors used for Env-mediated cell-cell fusion as well as infection by several dual-tropic HIV-1 isolates. Like 89.6, the R5X4 strain DH12 fused with and infected both wild-type and CCR5-negative macrophages. The CXCR4-specific inhibitor AMD3100 blocked DH12 fusion and infection in macrophages that lacked CCR5 but not in wild-type macrophages. This finding indicates two independent entry pathways in macrophages for DH12, CCR5 and CXCR4. Three primary isolates that use CXCR4 but not CCR5 (tybe, UG021, and UG024) replicated efficiently in macrophages regardless of whether CCR5 was present, and AMD3100 blocking of CXCR4 prevented infection in both CCR5 negative and wild-type macrophages. Fusion mediated by UG021 and UG024 Envs in both wild-type and CCR5-deficient macrophages was also blocked by AMD3100. Therefore, these isolates use CXCR4 exclusively for entry into macrophages. These results confirm that macrophage CXCR4 can be used for fusion and infection by primary HIV-1 isolates and indicate that CXCR4 may be the sole macrophage coreceptor for some strains. Thus, dual tropism can result from two distinct mechanisms: utilization of both CCR5 and CXCR4 on macrophages and T-cell lines, respectively (dual-tropic R5X4), or the ability to efficiently utilize CXCR4 on both macrophages and T-cell lines (dual-tropic X4).

Preferential coreceptor utilization and cytopathicity by dual-tropic HIV-1 in human lymphoid tissue ex vivo

Many HIV-1 isolates at the late stage of disease are capable of using both CXCR4 and CCR5 in transfected cell lines, and are thus termed dual-tropic. Here we asked whether these dual-tropic variants also use both coreceptors for productive infection in a natural human lymphoid tissue microenvironment, and whether use of a particular coreceptor is associated with viral cytopathicity. We used 3 cloned dual-tropic HIV-1 variants, 89.6 and its chimeras 89-v345.SF and 89-v345.FL, which use both CCR5 and CXCR4 in transfected cell lines. In human lymphoid tissue ex vivo, one variant preferentially used CCR5, another preferentially used CXCR4, and a third appeared to be a true dual-tropic variant. The 2 latter variants severely depleted CD4(+) T cells, whereas cytopathicity of the virus that used CCR5 only in lymphoid tissue was mild and confined to CCR5(+)/CD4(+) T cells. Thus, (a) HIV-1 coreceptor usage in vitro cannot be unconditionally extrapolated to natural microenvironment of human lymphoid tissue; (b) dual-tropic viruses are not homogeneous in their coreceptor usage in lymphoid tissue, but probably comprise a continuum between the 2 polar variants that use CXCR4 or CCR5 exclusively; and (c) cytopathicity toward the general CD4(+) T cell population in lymphoid tissue is associated with the use of CXCR4.

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.

A macrophage fusion assay for rapid screening of cloned HIV-1 Env using dual recombinant vaccinia viruses expressing distinct RNA polymerases

HIV-1 cell tropism is determined initially at the level of fusion mediated by the viral envelope glycoprotein (Env). Cell-cell fusion assays are employed widely to study Env-mediated fusion, and generally require transfection of target cells with a reporter plasmid that is activated upon fusion with Env-expressing effector cells. Macrophages are an important target for HIV-1, but fusion studies using primary macrophages are limited by their resistance to transfection. An assay described previously used recombinant vaccinia virus to express T7 polymerase in macrophages, and effector cells transfected with a T7-driven reporter plasmid and infected with recombinant vaccinia virus expressing Env. However, this requires a recombinant vaccinia virus for each Env. We developed a method to study fusion using primary macrophages and HIV-1 env plasmid clones under control of the T7 promoter. Macrophages were infected with a recombinant vaccinia virus expressing the SP6 RNA polymerase. Effector 293T cells were infected with a recombinant vaccinia virus expressing T7 polymerase, and co-transfected with T7-driven env plasmids and an SP6-driven reporter gene plasmid. Cell-cell fusion mediated by T7-driven Env results in SP6-driven reporter gene transactivation. This approach is suitable for rapid analysis of multiple primary isolate, chimeric, or mutant env genes cloned into plasmid vectors.

Effects of topical corticosteroids on inflammatory mediator-induced eicosanoid release by human airway epithelial cells

BACKGROUND

Airway epithelial cells are among the first cells to come in contact with aerosolized corticosteroids. However, the relative potencies and time course of action of the several commonly used aerosolized corticosteroids on eicosanoid production by airway epithelial cells are unknown.

OBJECTIVES

This study compared the effects of fluticasone, budesonide, and triamcinolone on eicosanoid output by human airway epithelial cells in vitro. We also determined the spectrum of eicosanoids affected and the mechanism for corticosteroid action.

METHODS

Cultured BEAS-2B airway epithelial cells (a transformed cell line) were exposed to corticosteroids (1 nmol/L to 1 micromol/L) for 2 to 48 hours and then assayed for basal- and bradykinin (BK)-stimulated eicosanoid output. The eicosanoid profile was identified by HPLC in tritiated arachidonic acid prelabelled cells, and PGE2, the major eicosanoid product, was quantitated by RIA. The effect of corticosteroids on the immunoreactivity of key proteins involved in eicosanoid metabolism (ie, cyclooxygenase [COX], phospholipase A2 [PLA2], and Clara cell protein, a PLA2 inhibitor) was determined by Western blotting.

RESULTS

Eicosanoid output was largely confined to prostaglandins with values of 5 +/- 2 and 82 +/- 35 ng PGE2/10(6) cells for basal- and BK stimulation, respectively (n = 8). All 3 corticosteroids inhibited basal- and BK-induced PGE2 output in a dose- and time-dependent manner. Fluticasone and budesonide completely eliminated PGE2 output in nanomolar concentrations in contrast to triamcinolone, which required micromolar concentration. The rank order of potency was: fluticasone = budesonide > triamcinolone. The time course of action for PGE2 inhibition also differed, with budesonide acting more slowly than the other 2 corticosteroids (P = .04). All 3 corticosteroids markedly reduced COX2 with little effect on COX1, cPLA2 (Type IV), or iPLA2 (Type VI) immunoreactivity or their relative distribution in cytosol versus membrane fractions. Clara cell protein immunoreactivity was undetectable in control and corticosteroid-treated cell lysates.

CONCLUSION

These results show that in a human airway epithelial cell line, the 3 inhaled corticosteroids commonly used to treat asthma differ in onsets of action as inhibitors of prostaglandin synthesis and vary considerably in potency. All 3 corticosteroids act mechanistically in similar fashion by inhibiting COX2 synthesis.

[The experimental investigation of epithelial healing in rabbit central corneal alkali wounds]

PURPOSE

To observe the morphologic changes of epithelium in the alkali wounds at the central corneal of rabbits.

METHODS

38 rabbits weighing 2.5 kg were used. A alkali wound of the corneas was performed in the right eye of 38 New Zealand white rabbits with round filter paper, 8 mm in diameter, which were soaked in 0.5 mol/L NaOH for 5 seconds and then were placed centrally on the cornea for 60 seconds. The corneal burns were examined and photographed after the staining of 2% fluoresent staining with a slit lamp every day. The excised corneas were examined in the light microscope, electron microscope.

RESULTS

The epithelial cells had rapidly disappeared in the burned area. The epithelial cells regrowth started at 8 hours following the burn, and 1-2 layers epithelial cells covered the burned area by 24 hours. The epithelial defects occured again on the 4th day. The desmosome and microvilli of the regenerating epithelium had a reduced number. There was no basement membrane between the regenerating epithelium and the strom. There were increased intercellular spaces between the regenerating epithalial cells.

CONCLUSION

The epithelial healing were achieved through the division and migration of epithelial cells at the margin of the wound in rabbit central corneal alkali wound. The decrease of the junctions and the increase of intercellular spaces between the regenerating epithalial cells may be responsible for the second epithelial defects.

Cofactors for human immunodeficiency virus entry into primary macrophages

Macrophages are permissive for macrophage-tropic (M-tropic) human immunodeficiency virus type 1 (HIV-1) isolates that use CCR5 for entry but are resistant to CXCR-4-dependent T cell-tropic prototype strains. M-tropic variants are critical for HIV-1 transmission, and persons who are homozygous for an inactivating mutation of CCR5 are resistant to HIV-1 in vivo. In vitro, their macrophages and lymphocytes are resistant to M-tropic strains that depend on CCR5. It is shown that CCR5-deficient macrophages are permissive for a dual-tropic isolate, 89.6, that uses CCR5, CXCR-4, and other cofactors. Entry by 89.6 into CCR5-deficient macrophages was blocked by the CXCR-4 ligand SDF and by an anti-CXCR-4 antibody. Immunoflorescence staining and reverse transcription PCR confirmed macrophage CXCR-4 expression. Thus, CXCR-4 on macrophages mediates entry of certain dual-tropic but not T cell-tropic isolates. Therefore, HIV-1 strains differ in how they utilize chemokine receptors as cofactors for entry, and the ability of a chemokine receptor to facilitate entry depends on the cell in which it is expressed.

[Expression and significance of Fas/APO-1 and Bcl-2 protein in human lung cancer.]

BACKGROUND

To investigate the role of Fas/APO-1 and Bcl-2 in oncogenesis and progression of lung cancer.

METHODS

The expression of Fas/APO-1 and Bcl-2 protein were detected in 65 lung cancer tissues and 46 normal lung tissues by immunohistochemistry.

RESULTS

The positive rate of Fas/APO-1 protein expression in lung cancer tissues was 56. 92 % , which was significantly lower than that in normal lung tissues (82. 61 %) ( P < 0. 01) . The positive rate of Bcl-2 protein expression was 46. 15 %. It was significantly higher than that in normal lung tissues (6. 52 %) ( P < 0. 01) .

CONCLUSIONS

Both Fas/APO-1 and Bcl-2 may play an role in the oncogenesis and progression of lung cancer.

Generation of enhancer trap lines in Arabidopsis and characterization of expression patterns in the inflorescence

Eleven thousand, three hundred and seventy enhancer/promoter trap lines in Arabidopsis were generated via T-DNA transformation utilizing the binary vector pD991 that contains a minimal promoter fused to the uidA reporter gene. Overall 31% of the lines generated exhibit a staining pattern in the inflorescence. Flanking DNA has been cloned from 15 lines exhibiting inflorescence staining patterns by either thermal asymmetric interlaced PCR (TAIL-PCR), inverse PCR (IPCR), or partial library construction. Seeds from these lines are available from the ABRC and NASC Arabidopsis stock centers and DNA pools are available from the ABRC.

[Separation and detection of tryptophan metabolites in biological samples]

A reversed phase HPLC method for separation and determination of the major tryptophan (TRP) metabolites in both pyrrolas pathway and TRP hydroxylase pathway, including TRP, kynurenine(KN), 3-hydroxykynurenine(3-HKN), kynurenic acid(KA), xanthurenic acid(XA), 5-hydroxytryptophan(5-HTP), 5-hydroxytryptamin(5-HT) and 5-hydroxyindoleacetic acid(5-HIAA), has been developed by sequential optimization of mobile phase based on acetate buffer and methanol. Trichloroacetic acid(TCA) was used as ion-pairing reagent to increase the retention of 3-HKN. The effects of pH and concentrations of TCA on separation were studied. Good separation can be achieved at pH 4.0-5.0 of mobile phase in less than 25 min. When TCA was not used, 3-HKN was hard to be detected in biological samples. The maximum retention of 3-HKN was obtained at pH 4.0 with mobile phase containing 50 mmol/L TCA. Combination of electrochemical (ED) and ultraviolet (UV) detection was used in which ED was responsible for detection of 3-HKN, 5-HTP, 5-HT and 5-HIAA and UV for the others. The influences of potential of ED and wavelength of UV on detection were studied. The optimization of conditions for separation and detection in different biological samples was also discussed.

Development of TGF-beta resistance during malignant progression

Transforming growth factor-beta (TGF-beta) is the prototypical multifunctional cytokine, participating in the regulation of vital cellular activities such as proliferation and differentiation as well as a number of basic physiological functions. The effects of TGF-beta are critically dependent on the expression and distribution of a family of TGF-beta receptors, the TGF-beta types I, II, and III. It is now known that a wide variety of human pathology can be caused by aberrant expression and function of these receptors. The coding sequence of the type II receptor (RII) appears to render it uniquely susceptible to DNA replication errors in the course of normal cell division. By virtue of its key role in the regulation of cell proliferation, TGF-beta RII should be considered as a tumor suppressor gene. High levels of mutation in the TGF-beta RII gene have been observed in a wide range of primarily epithelial malignancies, including colon and gastric cancer. It appears likely that mutation of the TGF-beta RII gene may be a very critical step in the pathway of carcinogenesis.

[Cerebral hemodynamic impairment and therapeutic effect of external counterpulsation on elderly patients with brain infarction]

Hemodynamic parameters of middle cerebral artery(MCA) were measured with Transcranial Doppler (TCD) in 31 elderly patients with brain infarction during convalescence and 28 healthy elderly controls. Twenty-two elderly patients with brain infarction and cerebral hemodynamic impaired were treated by External Counterpulsation(ECP). The results showed that the Vp and Vm of MCA in patients were significantly lower than that in the healthy controls(P < 0.001), the DVp, DVm and asymmetry of MCA in patients were greater than that in the healthy elderly(P < 0.001, P < 0.005). The Vp and Vm of MCA in patients after ECP were significantly higher than before(P < 0.001). The DVp, DVm and asymmetry of MCA in patients after ECP were significantly lower than before(P < 0.001, P < 0.005). The hemodynamic therapeutic effect is 81.8%.

[An investigation on chromosome aberration of SO-Rb50 cloned cell strains]

PURPOSE

To compare the differences of chromosome aberration among 3 cloning cells (MC2, MC3 and MC4) of SO-Rb50 cell line.

METHOD

G-banding and karyotype analysis were performed on the 11th passage cells of MC2, MC3 and MC4 cell strains.

RESULTS

Both numerical abnormal and structural aberrations of chromosomes could be observed in these 3 cloned cell strains. Diploid cells had the preponderance over the aneuploid cells. However, some cells showed pseudiploid karyotypes. Several kinds of structural chromosome aberrations were observed. The chromosome aberrations in the same passage of different cell strains were different. Aberration of chromosome 13 was rare and the aberration feature were different in 3 cloned cell strains. Five marker chromosomes were identified. M1, t(1;1) qterp35::q24-ter could be found in all cell strains. Other markers were seen in different cell strains respectively. In our experiment, two marker chromosome in chromosome 2, M4 and M5, were found in SO-Rb50 cell line for the first time.

CONCLUSION

Chromosome aberrations were different with different cloned cell strains. Combined with formerly study in SO-Rb50 cell line, we found the chromosome aberration had dynamic changes during the long-term culture in vitro. We suggest that aberration of chromosome 13 is not the only cause of Rb; aberration of chromosome 1, a common event in some neoplasias as well as in SO-Rb50, plays a meaningful role in the immortalization of this cell line; other aberrations observed in our experiment could be considered as evidences of genomic instability of the cell strains and presumably enhance the growth potential of the cells in which they develop.

[Morphological observation of the endogenous endophthalmitis of cryptococcus neoformans]

PURPOSE

To observe the pathologic change of the endogenous endophthalmitis of cryptococcus neoformans.

METHODS

Light and electron microscope were used.

RESULT

The choroid was focally tumor-like by an inflammatory cells infiltrate, which consisted of multinucleated gicant, epithelioid cells and lymphocytes. Special stains (Grocott's methnamine silver, PAS, alcian blue) and electron microscope disclosed the budding form of cryptococcus neoformans.

CONCLUSION

The morphologic examinations are only an effectivel method of diagrosing the endogenous endophthalmitis of cryptococcus neoformans.

[Studies on the chemical constituents of Smilax glabra]

Smilax glabra is a well-known traditional Chinese medicine which has been used clinically to prevent leptospirosis, to treat syphilis, and acute bacterial dysentery, etc. Its extracts showed anti-tumor and anti-atherosclerosis activity. A new isoflavone, 7,6'-dihydroxy 3'-methoxy isoflavone (1), along with two known compounds taxifolin (2) and astilbin (3), have been isolated from the roots of Smilax glabra. The structures were elucidated by spectroscopic methods including 2DNMR techniques.

An orphan seven-transmembrane domain receptor expressed widely in the brain functions as a coreceptor for human immunodeficiency virus type 1 and simian immunodeficiency virus

Both CD4 and an appropriate coreceptor are necessary for infection of cells by human immunodeficiency virus type 1 (HIV-1) and most strains of HIV-2. The chemokine receptors CCR5 and CXCR4 are the major HIV-1 coreceptors, although some virus strains can also utilize alternative coreceptors such as CCR3 to infect cells. In contrast, most if not all simian immunodeficiency virus (SIV) strains use CCR5 as a coreceptor, and many SIV strains can use CCR5 independently of CD4. In addition, several orphan seven-transmembrane receptors which can serve as HIV-1 and SIV coreceptors have been identified. Here we report that APJ, an orphan seven-transmembrane domain receptor with homology to the angiotensin receptor family, functions as a coreceptor for a number of HIV-1 and SIV strains. APJ was expressed widely in the human brain and in NT2N neurons. APJ transcripts were also detected by reverse transcription-PCR in the CD4-positive T-cell line C8166, but not in peripheral blood leukocytes, microglia, phytohemagglutinin (PHA)- or PHA/interleukin-2-stimulated peripheral blood mononuclear cells, monocytes, or monocyte-derived macrophages. The widespread distribution of APJ in the central nervous system coupled with its use as a coreceptor by some HIV-1 strains indicates that it may play a role in neuropathogenesis.

Influence of the CCR2-V64I polymorphism on human immunodeficiency virus type 1 coreceptor activity and on chemokine receptor function of CCR2b, CCR3, CCR5, and CXCR4

The chemokine receptors CCR5 and CXCR4 are used by human immunodeficiency virus type 1 (HIV-1) in conjunction with CD4 to infect cells. In addition, some virus strains can use alternative chemokine receptors, including CCR2b and CCR3, for infection. A polymorphism in CCR2 (CCR2-V64I) is associated with a 2- to 4-year delay in the progression to AIDS. To investigate the mechanism of this protective effect, we studied the expression of CCR2b and CCR2b-V64I, their chemokine and HIV-1 coreceptor activities, and their effects on the expression and receptor activities of the major HIV-1 coreceptors. CCR2b and CCR2b-V64I were expressed at similar levels, and neither molecule affected the expression or coreceptor activity of CCR3, CCR5, or CXCR4 in cotransfected cell lines. Peripheral blood mononuclear cells (PBMCs) from CCR2-V64I heterozygotes had normal levels of CCR2b and CCR5 but slightly reduced levels of CXCR4. CCR2b and CCR2b-V64I functioned equally well as HIV-1 coreceptors, and CCR2-V64I PBMCs were permissive for HIV-1 infection regardless of viral tropism. The MCP-1-induced calcium mobilization mediated by CCR2b signaling was unaffected by the polymorphism, but MCP-1 signaling mediated by either CCR2b- or CCR2-V64I-encoded receptors resulted in heterologous desensitization (i.e., limiting the signal response of other receptors) of both CCR5 and CXCR4. The heterologous desensitization of CCR5 and CXCR4 signaling by both CCR2 allele receptor types provides a mechanistic link that might help explain the in vivo effects of CCR2 gene variants on progression to AIDS as well as the reported antiviral activity of natural CCR2 ligands.

An intragenic suppressor of the Arabidopsis floral organ identity mutant apetala3-1 functions by suppressing defects in splicing

The Arabidopsis floral organ identity gene APETALA3 (AP3) specifies the identity of petals and stamens in the flower. In flowers mutant for the temperature-sensitive ap3-1 allele, the petals and stamens are partially converted to sepals and carpels, respectively. ap3-1 contains a single nucleotide change in the AP3 gene that alters both an amino acid in the AP3 protein and the 5' splice consensus site for intron 5. Surprisingly, the Ap3-1 mutant phenotype is not due to the missense mutation but instead is due to defects in splicing; specifically, exon 5 is frequently skipped by the splicing machinery at the restrictive temperature. In a screen for suppressors of ap3-1, we isolated an intragenic suppressor, ap3-11, that functions to suppress the splicing defects of ap3-1. Using a reverse transcriptase-polymerase chain reaction assay, we demonstrate that the percentage of full-length exon 5-containing AP3 RNAs correlates with the phenotype of the flowers in both ap3-1 and ap3-11. Rather surprisingly, the ap3-11 suppressor mutation is located in intron 4. One model explaining the function of ap3-11 is that the ap3-11 suppressor creates a novel branch point sequence that causes exon 5 to be more frequently recognized by the splicing machinery. The identification of such a suppressor strongly suggests that exon-scanning models of intron-exon recognition are operative in plants.

[The establishment, freezing-state preservation and resuscitation of retinoblastoma SO-Rb70 cell line]

PURPOSE

To establish a new cell line of human retinoblastoma (Rb), frozen and resuscitated to provide a Rb cell reservoir for clinical and experimental research.

METHODS

The screening cells were washed and blown directly without centrifugation and then inoculated. Based on the cell-frozen principle, the Rb cell line was collected and established, then frozen in liquid nitrogen and resuscitated.

RESULTS

SO-Rb70 cell line was established successfully. 8 groups of cells were frozen. The resuscitation experiment was carried out for 6 times, 4 times being successful.

CONCLUSION

The preserved human Rb cells in liquid nitrogen grew normally after resuscitation with the maintenance of previous bioactivities and characteristics. This research helped to provide abundant material for further study of Rb.

Determinants of entry cofactor utilization and tropism in a dualtropic human immunodeficiency virus type 1 primary isolate

Human immunodeficiency virus type 1 strain 89.6 is a dualtropic isolate that replicates in macrophages and transformed T cells, and its envelope mediates CD4-dependent fusion and entry with CCR5, CXCR-4, and CCR3. To map determinants of cofactor utilization by 89.6 and determine the relationship between cofactor use and tropism, we analyzed recombinants generated between 89.6 and T-cell-tropic (HXB) or macrophage-tropic (JRFL) strains. These chimeras showed that regions of 89.6 env outside V3 through V5 determine CXCR-4 utilization and T-cell line tropism as well as CCR5 utilization and macrophage tropism. However, the 89.6 env V3 domain also conferred on HXB the ability to use CCR5 for fusion and entry but not the ability to establish productive macrophage infection. CCR3 use was conferred on HXB by 89.6 env V3 or V3 through V5 sequences. While replacement of the 89.6 V3 through V5 region with HXB sequences abrogated CCR3 utilization, replacement of V3 or V4 through V5 separately did not. Thus, CCR3 use is determined by sequences within V3 through V5 and most likely can be conferred by either the V3 or the V4 through V5 domains. These results indicate that cofactor utilization and tropism in this dualtropic isolate are determined by complex interactions among multiple env segments, that distinct regions of the Env glycoprotein may be important for utilization of different chemokine receptors, and that determinants in addition to cofactor usage participate in postentry stages in the virus replication cycle that contribute to target cell tropism.