Rem2, a new member of the Rem/Rad/Gem/Kir family of Ras-related GTPases

Here we report the molecular cloning and biochemical characterization of Rem2 (for Rem, Rad and Gem-related 2), a novel GTP-binding protein identified on the basis of its homology with the Rem, Rad, Gem and Kir (RGK) family of Ras-related small GTP-binding proteins. Rem2 mRNA was detected in rat brain and kidney, making it the first member of the RGK family to be expressed at relatively high levels in neuronal tissues. Recombinant Rem2 binds GTP saturably and exhibits a low intrinsic rate of GTP hydrolysis. Surprisingly, the guanine nucleotide dissociation constants for both Rem2 and Rem are significantly different than the majority of the Ras-related GTPases, displaying higher dissociation rates for GTP than GDP. Localization studies with green fluorescent protein (GFP)-tagged recombinant protein fusions indicate that Rem2 has a punctate, plasma membrane localization. Deletion of the C-terminal seven amino acid residues that are conserved in all RGK family members did not affect the cellular distribution of the GFP fusion protein, whereas a larger deletion, including much of the polybasic region of the Rem2 C-terminus, resulted in its redistribution to the cytosol. Thus Rem2 is a GTPase of the RGK family with distinctive biochemical properties and possessing a novel cellular localization signal, consistent with its having a unique role in cell physiology.

[Detection of TT virus DNA by polymerase chain reaction-microplate hybridization]

OBJECTIVE

To establish a method for the detection of TT virus (TTV) DNA by polymerase chain reaction (PCR)-microplate hybridization and to find out various influential factors of the assay.

METHODS

TTV DNA extracted by guanidinium thiocyanate was amplified by PCR, the PCR primers were pre-labeled with biotin. By conjugation of biotin with streptavidin, the amplified products were coated to the microplate well, and hybridized with FITC- probe simultaneously. After being reacted with Anti-Fluorescein POD, the products that contained FITC probe were coloured by TMB-H2O2 and then measured the optical density using a microplate reader at 450 nm wavelength.

RESULTS

The optimal concentration of NaOH was 0.3 mol/L, and the optimal time of hybridization and enzymatic reaction was 60 minutes and 45 minutes, respectively. The results also showed that the positive rate of TTV infection in normal population, hepatitis A-G and hepatitis non A-G was 13.6%, 20.3% and 28.1%, respectively.

CONCLUSIONS

Comparing the PCR-microplate hybridization with the electrophoresis assay, the former is simple, rapid, sensitive and specific and is expected to be a new technique instead of electrophoresis assay as a routine method for TTV DNA detection.

Trehalose expression confers desiccation tolerance on human cells

Many organisms that withstand desiccation express the disaccharide trehalose. We have now expressed the otsA and otsB genes of Escherichia coli, which encode trehalose biosynthetic enzymes, in human primary fibroblasts using a recombinant adenovirus vector. Infected cells produced increased amounts of trehalose with increasing multiplicity of infection (MOI). Human primary fibroblasts expressing trehalose could be maintained in the dry state for up to five days. Fourier transform infrared spectroscopy indicated that dry, but viable, human cells contained no detectable water. This study shows that mammalian cells can be engineered to retain viability in the absence of water.

Characterization and gene structure of a novel retinoblastoma-protein-associated protein similar to the transcription regulator TFII-I

Retinoblastoma protein (Rb) is an important regulator of vertebrate cell cycle and development. It functions through a direct interaction with protein factors involved in cell cycle progression and differentiation. In the present study we characterized a novel Rb-associated protein, Cream1, which bound to Rb specifically through a C-terminal region. Cream1 contained 959 amino acid residues and migrated as a protein of approx. 120 kDa on SDS/PAGE. It was a widely expressed nuclear protein with a nuclear localization signal resembling that of the large T antigen of simian virus 40. Its primary sequence was characteristic of five direct repeats that were similar to, but distinct from, those of TFII-I, a multifunctional transcription regulator. Three additional regions were also highly conserved in both proteins. Cream1 exhibited an activation activity that was attributed to its N-terminal portion when assayed in yeast. Its relationship with the muscle-enhancer-binding protein MusTRD1 further suggests a role in regulating gene expression. The structural gene, CREAM1, contained 27 exons and spanned more than 150 kb. It was located at human chromosome 7q11.23 in a region deleted for Williams' syndrome, a neurodevelopmental disease with multisystem abnormalities, implying its involvement in certain disorders. Taken together, our results suggest that Cream1 might serve as a positive transcription regulator under the control of Rb.

A novel DNA damage checkpoint involving post-transcriptional regulation of cyclin A expression

The intracellular metabolism of many carcinogenic polycyclic aryl hydrocarbons (PAHs, typified by the ubiquitous pollutant benzo[a]pyrene or B[a]P) generates electrophilic products that react covalently with genomic DNA. Cells that acquire PAH-induced DNA damage undergo growth arrest in a p53-independent manner (Vaziri, C., and Faller, D. V. (1997) J. Biol. Chem. 272, 2762-2769). In this report we have investigated the molecular basis of PAH-induced cell cycle arrest. Mitogenic signaling events involving cyclins D and E, Rb phosphorylation, and transcriptional activation of E2F-responsive genes (including cyclin E and cyclin A) were unaffected in cells containing PAH-damaged DNA. However, PAH-induced growth arrest was associated with post-transcriptional decreases in cyclin A expression. Mitogen-induced expression of cyclin B, an event that is temporally distal to cyclin A expression, was also inhibited in PAH-treated cells. The PAH-induced cell cycle block was transient, and arrested cells resumed DNA synthesis after a prolonged ( approximately 20 h) delay. Resumption of DNA synthesis in PAH-treated cells occurred concomitant with elevated expression of cyclins A and B. PAH-induced cell cycle arrest was overcome by ectopically expressed cyclin A (encoded by a recombinant adenovirus in transiently infected cells). Overall, our results suggest the existence of a DNA damage checkpoint pathway that arrests cell cycle progression via post-transcriptional control of cyclin A expression.

Thrombospondin-1 promotes alpha3beta1 integrin-mediated adhesion and neurite-like outgrowth and inhibits proliferation of small cell lung carcinoma cells

Although human small cell lung carcinoma (SCLC) cell lines are typically anchorage-independent and do not attach on most extracellular matrix proteins, OH-1, and several other SCLC cell lines attached on substrates coated with thrombospondin-1 (TSP1). SCLC cells grew long-term as adherent cells on a TSP1-coated substrate. Adhesion of SCLC cells on TSP1 was inhibited by heparin, function-blocking antibodies recognizing alpha3 or beta1 integrin subunits, and by soluble alpha3beta1 integrin ligands. SCLC cells extended neurite-like processes on a TSP1 substrate, which was also mediated by alpha3beta1 integrin. Process formation on a TSP1 substrate was specifically stimulated by epidermal growth factor and somatostatin. Adhesion on TSP1 weakly inhibited SCLC cell proliferation, but this inhibition was strongly enhanced in the presence of epidermal growth factor. TSP1 and an alpha3beta1 integrin-binding peptide from TSP1 also inhibited proliferation when added in solution. High-affinity binding of 125I-labeled TSP1 to OH-1 cells was heparin-dependent and may be mediated by sulfated glycolipids, which are the major sulfated glycoconjugates synthesized by these cells. Synthesis or secretion of TSP1 by SCLC cells could not be detected. On the basis of these results, the alpha3beta1 integrin and sulfated glycolipids cooperate to mediate adhesion of SCLC cells on TSP1. Interaction with TSP1 through this integrin inhibits growth and induces neurotypic differentiation, which suggests that this response to TSP1 may be exploited to inhibit the progression of SCLC.

The peptide bond between E292-A293 of Escherichia coli leucyl-tRNA synthetase is essential for its activity

Escherichia coli leucyl-tRNA synthetase (LeuRS) is a class I aminoacyl-tRNA synthetase that contains a large connecting polypeptide (CP1) inserted into its nucleotide binding fold, or active site. In this study, purified leucyl-tRNA synthetase was found to be cleaved between E292 and A293 in its CP1 domain. SDS-PAGE analysis showed peptides of 63 and 34 kDa in addition to the native 97.3 kDa synthetase. By internal complementation, the two peptides could form a 97.3 kDa complex similar to the native LeuRS. This complex could support the ATP approximately PP(i) exchange activity of LeuRS, but could not complement for aminoacylation. To study the function of the region around the bond of E292 and A293, four pairs of peptides resulting from different cleavage sites in CP1 were reconstituted in vivo. With the exception of the enzyme assembled from the E292-A293 cleavage site, all the reassembled LeuRSs catalyzed the aminoacylation of tRNA(Leu). Although the E292-A293-cleaved LeuRS could not catalyze aminoacylation, fluorescence titration revealed that its tRNA binding ability was almost identical to that of wild-type LeuRS. These results suggest that the region around E292-A293 may be responsible for maintaining the proper conformation of LeuRS required for the tRNA charging activity.

[Allogeneic bone marrow transplantation for chronic myeloid leukemia: 118 cases analysis]

OBJECTIVE

To analyze the outcome of allogeneic bone marrow transplantation (allo-BMT) performed for chronic myeloid leukemia (CML) patients.

METHODS

One hundred and eighteen CML patients received allo-BMT with conditioning regimens of TBI or modified BU/CY. The pre-BMT situations were, 91 cases in first chronic phase (CP1), 19 in accelerating phase (AP), 2 in blast crisis (BC) and 6 in advanced CP (> CP2).

RESULTS

One hundred and nine patients were successfully engrafted. The probabilities of 5 year survival for CP1 and AP patients were 69.6% and 51.0%, and 5 year relapse rates were 3.2% and 12.5%, respectively.

CONCLUSIONS

Disease stage, conditioning regimen and splenomegaly did not affect the time for engraftment. For patients in CP1, splenomegaly was positively correlated with relapse. There was no difference between the effect of the two conditioning regimens on the prognosis.

[ABO-incompatible allogeneic bone marrow transplantation]

OBJECTIVE

To explore the immunohematological problems in ABO-incompatible allogeneic bone marrow transplantation (allo-BMT).

METHODS

Among 250 HLA-matched allo-BMTs, 61 were performed between ABO incompatible siblings. Out of these 61 BMTs, 38 were major ABO-incompatible and 23, minor. Control group included 61 HLA-matched Allo-BMTs with ABO compatible grafts. The major ABO incompatible patients received marrow grafts depleted of erythrocytes by hydroxyethyl starch (HES) sedimentation. The minor or bidirectional received marrow grafts depleted of plasma to reduce anti-A or anti-B agglutinins. ABO antigen and antibody in the recipients sera were determined once a week.

RESULTS

ABO-incompatible grafts for BMT had no adverse effect on engraftment, recovery of platelets, incidence of GVHD or survival. No recipient developed clinically hemolysis during or after marrow infusion. In ABO major compatible group, the onset of erythropoiesis after BMT was delayed and more RBC transfusions were required. Five of 10 recipients with blood group "O" in this group developed pure red cell aplasia (PRCA), lasting 7-24 months. Two of them recovered without therapeutic intervention. In the PRCA patients, the RBC antibody titers remained high for a longer time after BMT than in those whose erythropoiesis reconstituted timely. Serious morbidity related to ABO incompatibility did not occur.

CONCLUSION

ABO-incompatible allo-BMT is fairly safe if there is indication, however, PRCA may develop in isolated cases.

[Prophylaxis and treatment of cytomegalovirus infection in allogeneic bone marrow transplantation]

OBJECTIVE

To assess the efficacy and safety of Cymevene (ganciclovir) in the prophylaxis and treatment of cytomegalovirus (CMV) infection after allogeneic bone marrow transplantation (allo-BMT).

METHODS

Sixty patients with leukemia undergoing allo-BMT were observed. Cymevene was given prophylactically to 20 patients at a dose of 5 mg/kg twice daily from day -9 to day -2 and restarted when the ANC > or = 1.0 x 10(9)/L and BPC > or = 30 x 10(9)/L at a daily dose of 5 mg/kg for 5 days every week until day +100. In diagnosed symptomatic CMV infections, the dose of Cymevene was 5 mg/kg twice daily for 2-3 weeks followed by 5 mg/kg twice a day for 5 days every week for an additional 2-3 weeks.

RESULTS

The incidence of active CMV infection was 0 in the prophylaxis-treated patients and 25% in the controls (P < 0.05). In diagnosed CMV diseases, marked improvement was noted in 17 of 20 patients (85%) treated with Cymevene. The most common adverse events of Cymevene were leukopenia and thrombocytopenia, but were reversible.

CONCLUSION

Cymevene is effective and safe for the prophylaxis and treatment of CMV infections after allo-BMT.

Discrimination of tRNALeu isoacceptors by the insertion mutant of Escherichia coli leucyl-tRNA synthetase

A variant (LeuRS-A) of Escherichia coli leucyl-tRNA synthetase (LeuRS) carrying a 40-residue duplication in its connective peptide 1 (CP1) has a 3-fold lower specificity for than for, whereas wild-type LeuRS has the same specificity for these two isoacceptors. The replacement of the acceptor stem of with yields a chimeric tRNA(Leu) for which wild-type LeuRS has the same specificity as it does for the two normal isoacceptors mentioned, but for which LeuRS-A has a reduced specificity similar to that for, indicating a difference between these two acceptor stems. LeuRS-A is slightly less stable than the native enzyme. Wild-type LeuRS and LeuRS-A have almost same K(d) value for their interaction with as determined by fluorescence quenching. No difference was detected between these two proteins by CD and fluorescence spectroscopy. These results show that LeuRS-A can discriminate between the two isoacceptors of tRNA(Leu).

[Pulmonary complications occurring after allogeneic bone marrow transplantation]

OBJECTIVE

To explore the risk factors for and pathogenesis of pulmonary complications (PC) occurred after allogeneic bone marrow transplantation (allo-BMT).

METHODS

The PC in 185 patients undergone allo-BMT were analyzed.

RESULTS

Ninety-three PC episodes were observed in 89 patients and most of them were due to infections, including bacterial pneumonia (n = 27), interstitial pneumonia (n = 7), pulmonary fungus disease (n = 16), tuberculosis (n = 4), obstructive lung disease (n = 2), pulmonary edema (n = 2), lung abscess (n = 1) and 34 episodes caused by two or more pathogens. The overall mortality for PC was 12.43% (23/185).

CONCLUSION

The risk factors for PC occurred after allo-BMT were not related to age and sex of recipients, bone marrow status before BMT, conditioning regimen and pulmonary function. Graft-versus-host-disease significantly increased the morbidity and mortality of PC after allo-BMT.

Phenotypic characterization of neuroleptic-sensitive neurons in the forebrain: contrasting targets of haloperidol and clozapine

The prototypical neuroleptic haloperidol and the atypical antipsychotic clozapine induce distinctly different patterns of c-fos expression in the forebrain. While haloperidol appears to increase c-fos expression via its D2 dopamine receptor antagonist properties, the receptor mechanisms by which clozapine produces its unique pattern of c-fos expression are not known. The present experiments sought to address this question by determining the phenotypes of neurons in which clozapine increases Fos-like immunoreactivity (FLI). Fos immunostaining combined with in situ hybridization histochemistry using a cDNA oligonucleotide probe for D3 receptor mRNA indicated that the great majority (95%) of clozapine-induced FLI neurons in the major island of Calleja (ICjM) express D3 receptors. Similarly, in the nucleus accumbens (NAc) and lateral septal nucleus (LSN), the majority of clozapine-induced FLI neurons express D3 receptor mRNA (NAc 69%; LS 73%). In marked contrast, haloperidol-induced FLI neurons failed to express D3 receptors in any brain region. Studies with oligonucleotide probes for enkephalin (ENK) and dynorphin (DYN) indicated that clozapine increases c-fos expression in both ENK and DYN containing neurons in the NAc (ENK 40%, DYN 53%) and LSN (ENK 32%, DYN 59%). Haloperidol also increases c-fos expression in ENK and DYN containing neurons, albeit in a different pattern (striatum: ENK 93%, DYN 20%; nucleus accumbens: ENK 46%, DYN 36%; lateral septum: ENK 29%, DYN 18%). The present results demonstrate that haloperidol and clozapine target different populations of neurons even in regions such as the NAc and LSN, where they both increase c-fos expression. In addition, the fact that the majority of clozapine-sensitive neurons in NAc, LSN, and ICjM express D3 receptors suggests that activity at these receptors may contribute to the unique clinical profile of this antipsychotic agent. These data indicate that D3 receptors may represent novel targets in the pharmacotherapy of schizophrenia.

Differential roles of protein kinase C and pertussis toxin-sensitive G-binding proteins in modulation of melanoma cell proliferation and motility by thrombospondin 1

Thrombospondin 1 (TSP1) is an angiogenesis inhibitor that decreases tumor growth. We now report that TSP1 directly inhibits the proliferation of human melanoma cells. TSP1, peptides, and a recombinant fragment from the type I repeats, but not peptides that bind CD36 or CD47, inhibit the proliferation of A2058 melanoma cells. In contrast, chemotaxis is mediated by peptides or recombinant fragments from the procollagen, type I, type II, and cell-binding domains. The antiproliferative activity of TSP1 is mediated by a different signal transduction pathway than those mediating motility responses to the same protein. Activators of protein kinase A and protein kinase C inhibit chemotaxis but not the antiproliferative activity of TSP1, whereas the antiproliferative activity is reversed by inhibiting the tyrosine kinase or phosphatase activities. TSP1-mediated chemotaxis is partially dependent on a pertussis toxin (PT)-sensitive G-binding protein, whereas haptotaxis is not. Chemotaxis stimulated by the procollagen domain and the CD47-binding sequences from the COOH-terminal domain are also sensitive to PT, but responses to the type I and type III domains are not sensitive to PT. Residual chemotaxis to TSP1 in the presence of PT may therefore be mediated by the activities of the type I or type III repeats. Thus, TSP1 elicits several intracellular signals in melanoma cells that result from interactions with several domains of this protein and differentially affect growth and motility.

[A study on processing of the root of Astragalus membranaceus Bge. by HPLC]

The paper presents a study on the drug-processing of the root of Astragalus membranaceus. A HPLC method for the determination of astragaloside IV in its processed products has been established. The recovery is 96.1% and the RSD is 2.15%.

[Study on conversion of RARalpha/PML fusion gene in acute promyelocytic leukemia]

OBJECTIVE

To analyze the conversion of RARalpha/PML gene in acute promyelocytic leukemia (APL) patients before and after treatment with all-trans retinoic acid (ATRA) followed by intensive consolidation chemotherapy (ICC) and allogeneic bone marrow transplantation (allo-BMT).

METHODS

RARalpha/ PML fusion gene was detected in 22 APL patients before and after treatment by reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

RARalpha/PML fusion gene was positive in 75% of the patients after achieving complete remission with ATRA, and turned negative in 83% of the patients after ICC. The durations of conversion to the RT-PCR negative status varied from 1 to 39 months. Ten patients received allo-BMT, and all of them were RARalpha/PML fusion gene negative in 4 months post allo-BMT.

CONCLUSION

APL patients could achieve biological remission after ICC and allo-BMT, and the latter seemed to eliminate residual leukemic cells sooner in vivo than the former did.

Thrombospondin 1 and type I repeat peptides of thrombospondin 1 specifically induce apoptosis of endothelial cells

Thrombospondin 1 (TSP1) inhibits angiogenesis and modulates endothelial cell adhesion, motility, and growth. The antiproliferative activity of TSP1 is mimicked by synthetic peptides derived from the type I repeats of TSP1 that antagonize fibroblast growth factor 2 and activate latent transforming growth factor beta. These TSP1 analogues induced programmed cell death in bovine aortic endothelial cells based on morphological changes, assessment of DNA fragmentation, and internucleosomal DNA cleavage. Intact TSP1 also induced DNA fragmentation. The endothelial cell response was specific because no DNA fragmentation was induced in MDA-MB-435S breast carcinoma cells, although TSP1 and the peptide conjugates inhibited the growth of both cell types. Apoptosis did not depend on activation of latent transforming growth factor beta because peptides lacking the activating sequence RFK were active. Apoptosis was not sensitive to inhibitors of ceramide generation but was inhibited by the phosphatase inhibitor vanadate. Induction of DNA fragmentation by the peptides was decreased when endothelial cell cultures reached confluence. Growth of the cells on a fibronectin substrate also suppressed induction of apoptosis by TSP1 or the peptides. Differential sensitivities to kinase inhibitors suggest that apoptosis and inhibition of proliferation are mediated by distinct signal transduction pathways. These results demonstrate that induction of apoptosis by the TSP1 analogues is not a general cytotoxic effect and is conditional on a lack of strong survival-promoting signals, such as those provided by a fibronectin matrix. The antitumor activity of TSP1 may therefore result from an increased sensitivity to apoptosis in endothelial cells adjacent to a provisional matrix during formation of vascular beds in tumors expressing TSP1.

[The effect of interleukin (IL) 12 on hemopoiesis in irradiated mice]

OBJECTIVE

To investigate the regulating effect of IL-12 on hemopoiesis.

METHODS

cDNA coding for the two subunits of murine IL-12 were cloned into two different eukaryotic expression vectors and transduced into a same NIH3T3 cell line, resulting in two engineered fibroblast clones secreting IL-12. Cells were mixed with collagens and inoculated into the peritoneal cavities of whole-body-irradiated mice.

RESULTS

On day 10 after treatment, endogenous splenic colony-forming-unit (CFU-S) counts in mice treated with IL-12-secreting NIH3T3 cells were higher than those of mice accepting parental cells or untreated irradiated mice. This difference was statistically significant in both 6.0 Gy irradiated mice and 7.0 Gy group mice. Histopathological studies showed that NIH3T3-secreted IL-12 alleviates the injuries caused by irradiation in both bone marrow and spleen, activates hemopoietic cells, increases the number and scale of hemopoietic clusters, hence enhancing hemopoietic function including erythropoiesis, granulopoiesis, and megakaryocytopoiesis.

CONCLUSION

IL-12 up-regulates and promotes the recovery of hemopoietic function in irradiated mice.

[Experimental studies on the therapeutic effects of lung lavage with large volume of saline on silicosis]

Sterile saline was instilled into and aspirated from the lung of dust-exposed rabbits in imitation of clinical method of the whole-lung lavage. The changes of the biochemical and cellular components in alveolar fluid were observed before and after lavage with a view to providing evidence for the applicability of the method in the treatment of silicosis. The results showed that the number of cells, the protein content and the activities of both LDH and AKP were significantly lower than those of control group, except the total phospholipid and dipalmityl phosphatidyl choline (DPPC) in alveolar fluid after lavage. A certain amount of dust was also removed from lung with lavage. The wash-out of SiO2 from the first lavage was higher than that of the second lavage. It is suggested that lavage might delay the development of silicosis and be more effective in early stages of silicosis.

[A comprehensive evaluation of efficacy in treatments of pneumoconiosis with model method]

Pneumoconiosis is an occupational disease which can cause serious damage to the health of exposed workers. The study on the treatment of pneumoconiosis has been designated as a tackle-key-proble,. The exploration of comprehensive evaluation techniques is a component of this project. The model based on FUZZY SET is a mutivariate function [formula: see text], which can be used in the determination and evaluation of the efficacy in the treatments of pneumoconiosis. Its good performance has been proved in practice.

[Analysis on the tendency of practical dust exposure year and the out-of-dust rate among coalminers]

It is important to study the practical dust exposure year and out-of-dust rate for the evaluation of dust level and to predict pneumoconiosis incidence in coal miners. A Retrospective Cohort Study was carried out on the calculation of practical dust exposure year and the out-of-dust rate among coal miners employed during 1958-1988 in a mine. The results showed that job variety had a strong effect on dust exposure year and that out-of-dust rate beared relationship to the years of employment. It can be estimated that the percentage of coalminers who were employed in 1975-1979 with dust exposure year reached 20 years would be less than 30%, and that those being employed after 1980 would be even lesser.

Recombinant human granulocyte colony-stimulating factor after allogeneic bone marrow transplantation

OBJECTIVE

To examine the effect of rhG-CSF on allogeneic bone marrow transplantation.

PATIENTS AND METHODS

One hundred and twenty patients with acute or chronic leukemia received HLA-A.B.DR identical and MLC negative sibling donor allo-BMT. Among them, 58 cases of were treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF), while the other 62 cases of the 120 patients were treated as control.

RESULTS

Clinical results showed that the time taken to reach an absolute neutrophil count > 0.5 x 10(9)/L was significantly faster in patients who received rhG-CSF compared with control patients (16.24 +/- 0.25 vs 25.20 +/- 0.16 days. P < 0.001), with significantly less early fever days in patients received rhG-CSF (1.17 +/- 1.10 vs 4.01 +/- 0.37 P < 0.001). We did not observe any increase in acute GVHD and relapse in myeloid leukemia patients. But 7 of 16 patients with ALL relapsed after allo-BMT in rhG-CSF group, while only 3 of 11 patients with ALL relapsed after allo-BMT in control grant (P > 0.05). This phenomenon has not been reported up to now.

CONCLUSIONS

rhG-CSF can promote engraftment and reduce early fever days after BMT. rhG-CSF has not any effect on a GVHD. The effect of rhG-CSF on leukemia relapse needs to be further studied.

[Massive apoptosis in P815 mastocytoma in vivo induced by interleukin 2 gene transduction]

A study was carried out to determine the mechanisms of the P815 murine mastocytoma rejection. IL2 gene was transferred into the P815 mastocytoma cells by the retroviral vector. The transduced cells were selected with G418 (1 mg/ml). The single P815/IL2 cells were obtained through the limit dilution method. Using digoxigenin-labelled IL2 cDNA as the probe, IL2 mRNA expression was detected by in situ hybridization. The activity of IL2 dependent cell line in the cultural medium of P815/IL2 cells was assayed by MTT Color reaction with 30-147 U/ml per 10(6) cells every 24 hours. The detection of the proliferation activity indicated that P815/IL2 cells grew slower than the parental cells. IL2 gene modified P815 mastocytoma cells were inoculated into DBA/2 mice. The results showed that parental P815 cells produced tumors in 100% DBA/2 mice about 5-6 days after injection and grew progressively, but P815/IL2 tumor cells did not grow at all or did much later and completely regressed after a transient growth in mice. The ultrastructural studies indicated that the P815/IL2 cells in vivo had changed remarkably. The heterochromatin was increased and nuclei became irregular in shape. Immature and mature special granules appeared near the Golgi's complexes. The most impressive findings were massive apoptosis in the tumor tissues. Massive apoptosis must be specific for IL2 gene transduction, because it was not found in tumors produced by the parental cells. Apopotic cells were phagocytosed by macrophages and nearby tumor cells. Various cell infiltration, composed predominantly of eosinophils and macrophages were seen in the tumor tissue. The results suggested that the difference in differentiation of P815/IL2 cells in vivo might be induced by factors from the host. Tumor rejection may be the result of the multi-cell-mediated reaction including eosinophils, macrophages and other host cells.

Characterization of pathogenic fungi genomes using pulsed field gel electrophoresis

Pulsed field gel electrophoresis (PFGE) has been firstly introduced in characterization of the pathogenic fungi Penicillium marneffei and Exophiala dermatitidis genomes. The numbers and sizes of their chromosomes have been detected. Polymorphism was identified on the smallest chromosome of E. dermatitidis. The result shows that PFGE for characterization of large molecular DNA pathogenic fungi is very suitable, it is more simple and more efficacy. The result also shows the diversity of pathogenic fungi is relative common even in rare occurred pathogenic fungi such as E. dermatitidis.

Specific induction of fibronectin binding activity by hemoglobin in Candida albicans grown in defined media

Fibronectin (FN) is a major component of host extracellular matrix that may play an important role in the initiation and dissemination of Candida albicans infections. Expression of FN binding requires growth of C albicans blastoconidia in complex medium, and the regulation of FN receptor expression is poorly understood. We now demonstrate that hemoglobin is a potent and specific inducer of FN receptor expression and describe a defined medium supplemented with hemoglobin that greatly and stably enhances the binding activity of C. albicans for soluble FN. Enhancement of FN binding by hemoglobin in strain 44807 was concentration dependent and was maximal at 0.1% hemoglobin with 20- to 80-fold enhancement. The hemoglobin-induced FN binding to C. albicans was saturable, with a Kd of 2.7 X 10(-8) M. Enhancement required growth of C. albicans in hemoglobin-containing medium, since simply exposing blastoconidia to hemoglobin in a nongrowing status did not enhance binding. Induction was reversible following removal of hemoglobin from the growth medium and not associated with germination. Inorganic or protein-bound iron was not sufficient for the induction, since other iron-containing proteins or inorganic iron salts were inactive. Growth in the simple medium yeast nitrogen base supplemented with hemoglobin increased cell adhesion to immobilized FN and to cultured monolayers of bovine corneal endothelial cells. These data suggest that hemoglobin may be an important regulator of FN binding activity in C. albicans and thus may play a role in its pathogenesis.

Effects of systemic fluconazole therapy on in vitro adhesion of Candida albicans to buccal epithelial cells and changes of the cell surface proteins of the epithelial cells

This paper presented the effects of systemic fluconazole therapy via intravenous (IV) and oral (PO) administrations on the adhesion of Candida albicans (C. albicans) to the buccal epithelial cells (BEC) from five treated patients with three candidosis, one mucormycosis and one sporotrichosis and at the same time, an analysis of the cell surface proteins involving candidal adherent receptor in the BEC of the patients in the course of 7 days were exposed to 3H-leucine radiolabeled C. albicans for in vitro candidal adherent assay, and the BEC from first intake day and the last intake day of the patients were extracted by dithiothreitol (DTT)-iodoacetamide treatment for SDS-PAGE. These results indicate that the systemic fluconazole therapy results in the inhibitory effect of candidal adhesion to BEC of treated patients to prevent them from oral candidosis for a prolonged time, which is based on the absent surface protein (35 KDa) of the BEC.

Mouse surfactant protein-D. cDNA cloning, characterization, and gene localization to chromosome 14

Surfactant protein-D (SP-D) is a collectin found associated with surfactant in the lung. SP-D has also been functionally characterized as an opsonin for diverse microorganisms and a chemoattractant for phagocytic cells. To determine the structure of mouse SP-D, we isolated and characterized clones from a B6/CBAF1J strain lung cDNA library using a PCR-derived genomic probe. The deduced sequence predicts a 19-amino acid signal sequence, a 25-amino acid long NH2 terminus with two cysteines, followed by an uninterrupted collagen domain with 59 Gly-X-Y repeats. Next, a short "neck" domain of 28 amino acids, with a potential to form trimeric alpha-helical coiled coil is found ending in a COOH-terminal 125-amino acid carbohydrate recognition domain. The mature mouse SP-D protein of 355 amino acids shows strong homology to rat (92% identity), human (76%), and bovine (72%) SP-D amino acid sequences. Northern blot and RT-PCR analysis revealed that the mouse SP-D gene is expressed predominantly in lung and, surprisingly, also in heart, stomach, and kidney but not in brain. In contrast, mouse surfactant protein-A (SP-A) mRNA expression was found to be restricted to lung. Human lung and stomach, but not heart or liver, were found to express SP-D mRNA, as determined by PCR. The mouse SP-D gene (Sftp4) has been localized to chromosome 14 (to a region syntenic to human chromosome 10), closely linked to the genes for other collagenous lectins, mannose-binding protein-A (MbI1), and SP-A (Sftp1).

Mouse surfactant protein-D. cDNA cloning, characterization, and gene localization to chromosome 14

Surfactant protein-D (SP-D) is a collectin found associated with surfactant in the lung. SP-D has also been functionally characterized as an opsonin for diverse microorganisms and a chemoattractant for phagocytic cells. To determine the structure of mouse SP-D, we isolated and characterized clones from a B6/CBAF1J strain lung cDNA library using a PCR-derived genomic probe. The deduced sequence predicts a 19-amino acid signal sequence, a 25-amino acid long NH2 terminus with two cysteines, followed by an uninterrupted collagen domain with 59 Gly-X-Y repeats. Next, a short "neck" domain of 28 amino acids, with a potential to form trimeric alpha-helical coiled coil is found ending in a COOH-terminal 125-amino acid carbohydrate recognition domain. The mature mouse SP-D protein of 355 amino acids shows strong homology to rat (92% identity), human (76%), and bovine (72%) SP-D amino acid sequences. Northern blot and RT-PCR analysis revealed that the mouse SP-D gene is expressed predominantly in lung and, surprisingly, also in heart, stomach, and kidney but not in brain. In contrast, mouse surfactant protein-A (SP-A) mRNA expression was found to be restricted to lung. Human lung and stomach, but not heart or liver, were found to express SP-D mRNA, as determined by PCR. The mouse SP-D gene (Sftp4) has been localized to chromosome 14 (to a region syntenic to human chromosome 10), closely linked to the genes for other collagenous lectins, mannose-binding protein-A (MbI1), and SP-A (Sftp1).

[Karyotype analysis of Candida species by PFGE and its use in classicification]

Electrophoretic karyotype in 7 medically important Candida species was analyzed by pulsed-field gel electrophoresis. The chromosomal DNAs of the Candida species were separated into 4-10 bamds ranging in size from 0.5-2.8 Mb. These patterns were species-specific, so the electrophoretic karyotype can be used as a genotype basis for classification and identification of Candida species.

Receptor mechanisms mediating clozapine-induced c-fos expression in the forebrain

The atypical antipsychotic clozapine produces distinctly different regional patterns of c-fos expression in rat forebrain than does the prototypical neuroleptic haloperidol. While haloperidol-induced c-fos expression appears to be mediated by its D2 dopamine receptor antagonist properties, the mechanisms by which clozapine increases c-fos expression remain uncertain. Using a combination of brain lesion, pharmacological and immunohistochemical techniques, the present study sought to determine the receptor mechanisms by which clozapine increases the number of Fos-like immunoreactive neurons in various regions of the forebrain. To test whether serotonergic and/or noradrenergic systems are involved in clozapine-induced c-fos expression, rats received either 5,7-dihydroxytryptamine lesions of the medial forebrain bundle or 6-hydroxydopamine lesions of the dorsal noradrenergic bundle two weeks prior to clozapine (20 mg/kg) injections. Neither type of lesion affected clozapine-induced c-fos expression in the rat forebrain, suggesting that neither serotonergic nor noradrenergic mechanisms are involved in this action of clozapine. In another experiment, the 5-hydroxytryptamine2 receptor antagonist ritanserin (5 mg/kg), either alone or in combination with haloperidol (1 mg/kg), failed to mimic the pattern of c-fos expression produced by clozapine. This suggests that clozapine's antagonist actions at 5-hydroxytryptamine2 receptors cannot explain the unique pattern of regional c-fos expression produced by this compound. To determine whether the blockade of subtypes of the D2 dopamine receptor family may contribute to clozapine's effects, the dopamine receptor agonists quinpirole and 7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) were injected 15 min prior to clozapine. Quinpirole produced a small but significant decrease in clozapine-induced c-fos expression in the medial prefrontal cortex, had larger effects in the lateral septum, and blocked clozapine's actions in the nucleus accumbens and major island of Calleja. Pretreatment with 7-OH-DPAT attenuated clozapine-induced c-fos expression in the nucleus accumbens and lateral septum, completely blocked the expression in the major island of Calleja, but was without effect in the medial prefrontal cortex. Given the different affinities of quinpirole and 7-OH-DPAT for D2, D3 and D4 receptors, these data suggest that clozapine-induced increases in c-fos expression in the nucleus accumbens, major island of Cajella and lateral septal nucleus are due to antagonist actions of this antipsychotic at D3 dopamine receptors. They also indicate that while antagonist actions at D4 receptors may contribute, the primary mechanisms by which clozapine increases c-fos expression in the medial prefrontal cortex remain to be determined.

[Ondansetron in the prophylaxis of acute emesis induced by supra-high single dose total body irradiation (TBI)]

One hundred sixteen cases of leukemia patients received supra-high single dose TBI for bone marrow transplantation (BMT) with total a radiation dosage of 700-770 Gy at about 5cGy/min. Seventy patients were given ondanstron (8mg) plus dexamethasone (DXM, 10mg) for prophylaxis of TBI-induced acute nausea and vomiting, 46 patients were given paspertin (10mg) plus dexamethasone (10mg) as controls. The clinical results showed that ondansetron plus DXM achieved complete or major control of vomiting in 59/70 (84%) of cases and there was little or no nausea in 61/70 (87%), while paspertin plus DXM achieved complete or major control of vomiting only in 9/46 (20%) of cases and little or no nausea in 5/46 (11%). It is concluded that ondansetron has significantly greater advantage over paspertin in the control of acute emesis induced by TBI.

[The adherence reaction between Candida and cultured cell in vitro]

The adherence reaction between Candida and cultured cells in vitro was studied. After the comparison between two fungal phases, two different ratios of cells to fungi and two different incubation temperature, we found that the better adhesion condition is at 37 degrees C, with a concentration of cell to fungi of 1:200 and with the Candida albicans in the germ tube phase. We also found 4 different materials that could inhibit C. albicans adherence.

Activated T-cell adhesion to thrombospondin is mediated by the alpha 4 beta 1 (VLA-4) and alpha 5 beta 1 (VLA-5) integrins

T lymphocytes utilize adhesion receptors in a regulated manner to interact with other cells and with components of the extracellular matrix. These cell-cell and cell-matrix interactions serve a critical role in T cell recognition of foreign Ag and in the migration of T cells to various anatomic sites in vivo. Thrombospondin is an extracellular matrix protein that is transiently expressed at high concentration in damaged and inflamed tissue. Given recent evidence implicating a role for the extracellular matrix in modulating T-cell migration and function, we analyzed T-lymphocyte interactions with thrombospondin. We show here that CD4+ T cells specifically adhere to thrombospondin predominantly via the 70 kDa core region of the thrombospondin molecule. Antibody blocking and affinity chromatography analysis suggest that T-cell adhesion to thrombospondin involves three distinct receptors: an activation-independent receptor that mediates adhesion of resting T cells, and the alpha 4 beta 1 and alpha 5 beta 1 integrins, which mediate a rapid increase in adhesion to thrombospondin upon activation. These three molecules appear to be novel thrombospondin receptors, as other receptors previously implicated in the adhesion of nonlymphoid cells to thrombospondin appear not to be involved in T-cell/thrombospondin interactions. The up-regulation of alpha 4 beta 1 and alpha 5 beta 1 functional activity upon activation is associated with the preferential adhesion of memory T cells to thrombospondin. Our results thus define three novel thrombospondin receptors, and provide additional evidence that extracellular matrix proteins play an important role in lymphocyte migration into, and retention in, inflammatory sites.

Activated T-cell adhesion to thrombospondin is mediated by the alpha 4 beta 1 (VLA-4) and alpha 5 beta 1 (VLA-5) integrins

T lymphocytes utilize adhesion receptors in a regulated manner to interact with other cells and with components of the extracellular matrix. These cell-cell and cell-matrix interactions serve a critical role in T cell recognition of foreign Ag and in the migration of T cells to various anatomic sites in vivo. Thrombospondin is an extracellular matrix protein that is transiently expressed at high concentration in damaged and inflamed tissue. Given recent evidence implicating a role for the extracellular matrix in modulating T-cell migration and function, we analyzed T-lymphocyte interactions with thrombospondin. We show here that CD4+ T cells specifically adhere to thrombospondin predominantly via the 70 kDa core region of the thrombospondin molecule. Antibody blocking and affinity chromatography analysis suggest that T-cell adhesion to thrombospondin involves three distinct receptors: an activation-independent receptor that mediates adhesion of resting T cells, and the alpha 4 beta 1 and alpha 5 beta 1 integrins, which mediate a rapid increase in adhesion to thrombospondin upon activation. These three molecules appear to be novel thrombospondin receptors, as other receptors previously implicated in the adhesion of nonlymphoid cells to thrombospondin appear not to be involved in T-cell/thrombospondin interactions. The up-regulation of alpha 4 beta 1 and alpha 5 beta 1 functional activity upon activation is associated with the preferential adhesion of memory T cells to thrombospondin. Our results thus define three novel thrombospondin receptors, and provide additional evidence that extracellular matrix proteins play an important role in lymphocyte migration into, and retention in, inflammatory sites.

Inhibition of fibronectin binding and fibronectin-mediated cell adhesion to collagen by a peptide from the second type I repeat of thrombospondin

The platelet and extracellular matrix glycoprotein thrombospondin interacts with various types of cells as both a positive and negative modulator of cell adhesion, motility, and proliferation. These effects may be mediated by binding of thrombospondin to cell surface receptors or indirectly by binding to other extracellular matrix components. The role of peptide sequences from the type I repeats of thrombospondin in its interaction with fibronectin were investigated. Fibronectin bound specifically to the peptide Gly-Gly-Trp-Ser-His-Trp from the second type I repeat of thrombospondin but not to the corresponding peptides from the first or third repeats or flanking sequences from the second repeat. The two Trp residues and the His residue were essential for binding, and the two Gly residues enhanced the affinity of binding. Binding of the peptide and intact thrombospondin to fibronectin were inhibited by the gelatin-binding domain of fibronectin. The peptide specifically inhibited binding of fibronectin to gelatin or type I collagen and inhibited fibronectin-mediated adhesion of breast carcinoma and melanoma cells to gelatin or type I collagen substrates but not direct adhesion of the cells to fibronectin, which was inhibited by the peptide Gly-Arg-Gly-Asp-Ser. Thus, the fibronectin-binding thrombospondin peptide Gly-Gly-Trp-Ser-His-Trp is a selective inhibitor of fibronectin-mediated interactions of cells with collagen in the extracellular matrix.

A strain of urease negative Cryptococcus neoformans isolated from the environment in China

This is the first report of a strain of urease negative Cryptococcus neoformans isolated from the environment in China. The colonies of this isolate showed brown pigmentation on cornmeal agar with 300 micrograms/ml caffeic acid, but failed to hydrolyze urea. Microbiological identification and pathogenicity tests in mice confirmed this as a strain of C. neoformans. A similar strain had reportedly been isolated from an AIDS patient.

Glutathione: new candidate neuropeptide in the central nervous system

The physiological significance of glutathione in the mammalian central nervous system is still uncertain, although some evidence indicates that it may be an important regulatory peptide. In the present study, the distribution and characteristics of glutathione binding sites in the brain have been studied. Biotinyl-glutathione was synthesized as a probe to detect glutathione binding sites in the CNS. Specific glutathione binding sites in the brain were largely localized to the white matter, suggesting the presence of glutathione receptors on neuroglial cells. The colloidal gold technique and immunofluorescence double staining allowed the visualization of the receptor at the cellular level and thus demonstrated that there are glutathione receptors on cultured astrocytes. Glutathione applied to cultured astrocytes elicited increased levels of intracellular inositol-1,4,5-trisphosphate, suggesting that glutathione receptors were coupled to phospholipase C. The localization of glutathione receptors on astrocytes and the activation of a second messenger system by glutathione suggest that glutathione may be a neuropeptide in the central nervous system.

Characterization and localization of glutathione binding sites on cultured astrocytes

Glutathione (GSH) binding sites found in brain white matter in a previous study using biotinylated GSH (Third IBRO World Congress Neurosci. Abstr., 1991, P59.17) suggested that there might GSH receptors on glial cells. In the present study, radioligand receptor assays were performed on cultured astrocytes using [35S]GSH. Scatchard analyses of saturation binding of [35S]GSH revealed two binding sites: Kd1 = 2.0 +/- 0.1 nM, Bmax1 = 89.5 +/- 1.5 fmole/2.2 x 10(5) cells and Kd2 = 12.8 +/- 0.4 nM, Bmax2 = 187.7 +/- 2.4 fmol/2.2 x 10(5) cells. The saturable and displacible high affinity [35S]GSH binding we have observed suggests that this binding is not due to GSH sequestration by uptake sites or to the association of GSH with GSH S-transferases or GSH peroxidases which have Kds in the microM range. Colloidal gold and immunofluorescence double labelling were used to visualize the binding sites at the cellular level. Positive colloidal gold decoration further suggests that these labelled binding sites are membrane receptors on astrocytes.

Scopolamine attenuates haloperidol-induced c-fos expression in the striatum

Haloperidol increases the expression of Fos, the protein product of the proto-oncogene c-fos, in some parts of the central nervous system. Haloperidol also produces catalepsy in rodents and extrapyramidal side effects in humans, both of which are reduced by muscarinic receptor antagonists. In order to gain insight into the neurochemical and neuroanatomical substrates of haloperidol-induced catalepsy we examined the effects of the muscarinic receptor antagonist scopolamine on haloperidol-induced Fos expression in the striatum, nucleus accumbens and lateral septal nucleus. At a dose that reduced the cataleptic effect of haloperidol, scopolamine decreased the neuroleptic-induced Fos expression in the striatum and lateral septal nucleus but not the nucleus accumbens. These results indicate that haloperidol may increase c-fos expression in medium spiny striatal neurons indirectly by enhancing striatal acetylcholine release. They are also consistent with the hypothesis that neuroleptic-induced increases in striatal c-fos expression are predictive of extrapyramidal side effects produced by these compounds.

[Protective effect of glycyrrhizine in mice with systemic Candida albicans infection and its mechanism]

We proved that a Chinese herb extract--Glycyrrhizine, the sweet component of Licorice root--protected mice from Candida albicans infection in doses of 0.5 mg/(kg.d) for 15-20 d. After administration of the above doses, the mortality rate of infected mice was decreased from 100% to 65%; the survival time was extended from 6.76 +/- 1.95 to 10.99 +/- 7.24 days after infection with lethal spores; and the toxic symptoms were also alleviated. The mechanism of protection is probably related to several factors, such as plasma opsonin activity promotion, enhancement of NK cell activity, increasing levels of plasma SOD, etc. All of this indicates that GCZ might be used as an accessory drug in the treatment of severe fungal infection.

Immunoprecipitation of membrane proteins from rat basophilic leukemia cells by the antiganglioside monoclonal antibody AA4

In previous studies, mAb AA4 inhibited IgE binding, induced rapid morphologic changes, and blocked histamine release in rat basophilic leukemia (RBL-2H3) cells. It bound to two novel derivatives of ganglioside GD1b (Ag I and Ag II) that appear to be present only in rat mast cells. The present study demonstrates the importance of gangliosides Ag I and Ag II for binding of mAb AA4 to intact cells. We also investigated the presence of gangliosides Ag I and Ag II and proteins immunoprecipitated with mAb AA4 in the parental and four variant cell lines. In comparison with the parental RBL-2H3, two variant cell lines had very low (0.5% and 2.0%) and two others had intermediate levels (9% and 18%) of 125I-AA4 binding. mAb AA4 inhibited 125I-IgE binding to the parental RBL-2H3 cells and to only one variant with intermediate amounts of gangliosides Ag I and Ag II. Therefore, there are variations in the proximity of these gangliosides to the high affinity IgE receptor (Fc epsilon RI) among different cell lines. mAb AA4 immunoprecipitated proteins of 50 to 60, 120, and 135 kDa from 125I-surface labeled cells. These were different from the subunits of Fc epsilon RI. The amount of gangliosides Ag I and Ag II in cell extracts correlated with the number of mAb AA4 binding sites on the cell surface and with the quantity of proteins precipitated from the different cell lines. Thus, these membrane proteins appear to be associated with gangliosides Ag I and Ag II. The binding of mAb AA4 to the surface gangliosides could induce intracellular changes through transmembrane signaling by these proteins.

Immunoprecipitation of membrane proteins from rat basophilic leukemia cells by the antiganglioside monoclonal antibody AA4

In previous studies, mAb AA4 inhibited IgE binding, induced rapid morphologic changes, and blocked histamine release in rat basophilic leukemia (RBL-2H3) cells. It bound to two novel derivatives of ganglioside GD1b (Ag I and Ag II) that appear to be present only in rat mast cells. The present study demonstrates the importance of gangliosides Ag I and Ag II for binding of mAb AA4 to intact cells. We also investigated the presence of gangliosides Ag I and Ag II and proteins immunoprecipitated with mAb AA4 in the parental and four variant cell lines. In comparison with the parental RBL-2H3, two variant cell lines had very low (0.5% and 2.0%) and two others had intermediate levels (9% and 18%) of 125I-AA4 binding. mAb AA4 inhibited 125I-IgE binding to the parental RBL-2H3 cells and to only one variant with intermediate amounts of gangliosides Ag I and Ag II. Therefore, there are variations in the proximity of these gangliosides to the high affinity IgE receptor (Fc epsilon RI) among different cell lines. mAb AA4 immunoprecipitated proteins of 50 to 60, 120, and 135 kDa from 125I-surface labeled cells. These were different from the subunits of Fc epsilon RI. The amount of gangliosides Ag I and Ag II in cell extracts correlated with the number of mAb AA4 binding sites on the cell surface and with the quantity of proteins precipitated from the different cell lines. Thus, these membrane proteins appear to be associated with gangliosides Ag I and Ag II. The binding of mAb AA4 to the surface gangliosides could induce intracellular changes through transmembrane signaling by these proteins.