Leaf morphology and cuticular features of Sphenophyllum in the Gigantopteris flora from South China

Permian specimens of Sphenophyllum with preserved cuticular anatomy have been discovered in Cathaysia and have prompted a detailed re-evaluation of the genus in the Gigantopteris flora in South China. New specimens are described and previously published material is re-examined to clarify taxonomic diversity and to establish geographic and stratigraphic ranges for each species. Recognized taxa include Sphenophyllum apiciserratum sp. nov., S. koboense Kobatake, S. meridionale sp. nov., S. minor (Sterzel) Gu and Zhi, S. sinocoreanum Yabe, S. cf. sinocoreanum Yabe, and S. aff. speciosum (Royle) McClelland. Cuticles of Sphenophyllum apiciserratum and S. koboense are hypostomatic with randomly disposed ordinary cells in intercostal regions. Specific concepts are clarified and unresolved taxonomic problems are discussed. The South China taxa are compared with those from Euramerican, Gondwanan and Angaran floras, and the South China Cathaysian species are found to be taxonomically distinct.

ERK1b, a 46-kDa ERK isoform that is differentially regulated by MEK

We identified a 46-kDa ERK, whose kinetics of activation was similar to that of ERK1 and ERK2 in most cell lines and conditions, but showed higher fold activation in response to osmotic shock and epidermal growth factor treatments of Ras-transformed cells. We purified and cloned this novel ERK (ERK1b), which is an alternatively spliced form of ERK1 with a 26-amino acid insertion between residues 340 and 341 of ERK1. When expressed in COS7 cells, ERK1b exhibited kinetics of activation and kinase activity similar to those of ERK1. Unlike the uniform pattern of expression of ERK1 and ERK2, ERK1b was detected only in some of the tissues examined and seems to be abundant in the rat and human heart. Interestingly, in Ras-transformed Rat1 cells, there was a 7-fold higher expression of ERK1b, which was also more responsive than ERK1 and ERK2 to various extracellular treatments. Unlike ERK1 and ERK2, ERK1b failed to interact with MEK1 as judged from its nuclear localization in resting cells overexpressing ERK1b together with MEK1 or by lack of coimmunoprecipitation of the two proteins. Thus, ERK1b is a novel 46-kDa ERK isoform, which seems to be the major ERK isoform that responds to exogenous stimulation in Ras-transformed cells probably due to its differential regulation by MEK.

99mTc-HL91 "hot spot" imaging of mice bearing human carcinoma by gamma camera and the effects of tumor necrosis on imaging

OBJECTIVE

To evaluate the hypoxia-avid agent 99mTc-HL91 (99mTc labeled 4, 9-diaza-3, 3, 10, 10-tetramethyldodecan-2, 11-dione dioxime) as the tracer of tumor "hot spot" imaging and the influence of tumor necrosis on the image.

METHODS

After injection of 99mTc-HL91, 6 nude mice bearing human breast cancer MCF-7 and 18 nude mice bearing human pancreatic adenocarcinoma were subjected to gamma camera imaging, postmortem analysis, and autoradiography and imaging of tumor sections.

RESULTS

The image of tumor was identified 1 hour after injection of 99mTc-HL91. Images demonstrated gradually increased 99mTc-HL91 uptake in the tumor 1-12 hours after injection (P < 0.05-0.001). Six hours after injection, the radioactivity ratios of tumor to thorax and tumor to head were higher than 2.1. Six hours after injection, the radioactivity ratios of tumor to brain, muscle, blood, heart, lung and kidney in pancreatic adenocarcinoma bearing nude mice were 101.0 +/- 114.7, 30.0 +/- 30.3, 19.9 +/- 21.9, 14.4 +/- 15.1, 3.71 +/- 2.41 and 0.46 +/- 0.26, respectively, and the radioactivity ratios in breast cancer MCF-7 bearing nude mice were close to these figures. The radioactivity of non-necrotic tumor was 3.77 times that of necrotic tumor. However, the radioactivity ratios of tumor to liver, intestine and stomach were lower than 1.3. Autoradiographs and images of tumor sections showed that the radioactivity was higher in the region of solid tumor than in the necrotic region.

CONCLUSION

99mTc-HL91 via gamma camera positively identifies regional tumor in nude mice bearing human cancer. 99mTc-HL91 retention is lower in necrotic tumor than in non-necrotic tumor. The low radioactivity ratio of tumor to abdominal organs limits the application of 99mTc-HL91 in detecting abdominal tumors.

99mTc-MIBI and 99mTc-MDP scintimammography for detecting breast carcinoma

OBJECTIVE

To assess the value of scintimammography with both 99mTc-MIBI and 99mTc-MDP in detecting breast cancer.

METHODS

A total of 35 women with clinical findings of suspicious breast lesions were studied with both 99mTc-MIBI and 99mTc-MDP scintimammography. All patients underwent surgery within one week and the final diagnostic results (histopathological) were obtained.

RESULTS

Eighteen of 35 abnormalities of breast were pathologically confirmed as breast cancer and 17 as benigN lesions. In this group of patients studied, the sensitivity, specificity and accuracy of 99mTc-MIBI scintimammography were 77.8%, 88.2% and 82.9%, respectively and those of 99mTc-MDP scintimammography were 72.2%, 88.2% and 80.0%, respectively. There was no significant difference between 99mTc-MIBI and 99mTc-MDP scintimammography.

CONCLUSION

This study showed the high diagnostic accuracy of both 99mTc-MIBI and 99mTc-MDP scintimammography in detecting breast cancer. Both can be used as non-invasively assess breast cancer invasiveness before surgery.

Phosphorylation and destabilization of human period I clock protein by human casein kinase I epsilon

Period (PER), a central component of the circadian clock in Drosophila, undergoes daily oscillation in abundance and phosphorylation state. Here we report that human casein kinase I epsilon (hCKI epsilon) can phosphorylate human PER I (hPER I). Purified recombinant hCKI epsilon (but not a kinase negative mutant of hCKI epsilon, hCKI epsilon-K38R) phosphorylated hPER I in vitro. When co-transfected with wild-type hCKI epsilon, in 293T cells, hPER I showed a significant increase in phosphorylation as evidenced by a shift in molecular mass. Furthermore, phosphorylation of hPER I by hCKI epsilon caused a decrease in protein stability in hPER I. Whereas phosphorylated hPER I had a half-life of approximately 12 h, unphosphorylated hPER I remained stable in the cell for > 24 h. hPER I protein could also be co-immunoprecipitated with transfected hCKI epsilon as well as endogenous hCKI epsilon, indicating physical association between hPER I and hCKI epsilon proteins in vivo.

[Generation of cytotoxic T lymphocytes induced with HSP-PC70 derived from tumor cells]

OBJECTIVE

To investigate the killing effect of cytotoxic T lymphocytes (CTLs) induced with heat shock protein-peptide complexes (HSP-PC70) derived from tumor cells.

METHODS

Cell culture, flow cytometric analysis, affinity chromatography for protein extraction and purification, SDS-PAGE, Western blotting, CTL induction and expansion, and LDH release were used.

RESULTS

63.5% of the HcaF cells expressed HSP-PC70 on their membrane by FCM analysis under physiological condition, and the expression was 75.5% of the stressed cells (P < 0.01). HcaF cells had high HSP70 expression and inducibility. The cytotoxic activity of the CTLs induced with HSP70 obtained by affinity chromatography from HcaF cells was 84.2%, 47.9% and 14.8% respectively at E/T ratio of 50 : 1, 25 : 1 and 12.5 : 1. The CTLs were CD8 positive T cells. All mice which received CTL injection got long period survival (over 90 days, P < 0.01), compared with control group (10.6 days).

CONCLUSION

HSP-PC70 derived from tumor cells has strong immunogeneicity, and can activate CTLs with high peculiarity and killing activity. HSP-PC70 induced CTL adoptive immunotherapy can be a promising treatment for human to fight cancers.

High-field electrical transport in single-wall carbon nanotubes

Using low-resistance electrical contacts, we have measured the intrinsic high-field transport properties of metallic single-wall carbon nanotubes. Individual nanotubes appear to be able to carry currents with a density exceeding 10(9) A/cm(2). As the bias voltage is increased, the conductance drops dramatically due to scattering of electrons. We show that the current-voltage characteristics can be explained by considering optical or zone-boundary phonon emission as the dominant scattering mechanism at high field.

Detection of partially phosphorylated forms of ERK by monoclonal antibodies reveals spatial regulation of ERK activity by phosphatases

When cells are stimulated by mitogens, extracellular signal-regulated kinase (ERK) is activated by phosphorylation of its regulatory threonine (Thr) and tyrosine (Tyr) residues. The inactivation of ERK may occur by phosphatase-mediated removal of the phosphates from these Tyr, Thr or both residues together. In this study, antibodies that selectively recognize all combinations of phosphorylation of the regulatory Thr and Tyr residues of ERK were developed, and used to study the inactivation of ERK upon mitogenic stimulation. We found that inactivation of ERK in the early stages of mitogenic stimulation involves separate Thr and Tyr phosphatases which operate differently in the nucleus and in the cytoplasm. Thus, ERK is differentially regulated in various subcellular compartments to secure proper length and strength of activation, which eventually determine the physiological outcome of many external signals.

Effect of 1,25(OH)2D3 on the growth and apoptosis of breast cancer cell line MCF-7

OBJECTIVE

To study the effect of 1, 25-dihydroxyvitamin D3(1,25(OH)2D3) on the growth and apoptosis of breast cancer cell line MCF-7.

METHODS

Cell number was determined using the MTT method. Flow cytometric analysis was performed on cell cycles, and the percentage of apoptosis was counted. Apoptotic cells were quantified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and bcl-2 protein expression was estimated with Western blotting.

RESULTS

After incubation with 1,25(OH)2D3 10(-7) mol/L for 48 hours, MCF-7 cells exhibited significant growth in a dose- and time-dependent manner. Flow cytometric analysis indicated that cell numbers in G0/G1 increased along with increasing apoptotic peak and percentage. With microscope and electron microscope observation, characteristics of apoptosis such as typical apoptotic bodies were commonly found. TUNEL also showed that 1,25(OH)2D3 10(-8) mol/L and 10(-7) mol/L groups had significantly high apoptosis percentage than control group with dose-dependence on induction apoptosis. And Western blot showed that 1,25(OH)2D3 10(-8) mol/L could down-regulate bcl-2 protein and 10(-7) mol/L could almost block bcl-2 protein expression.

CONCLUSIONS

1,25(OH)2D3 can inhibit cell growth with G0/G1 arrest, enhance the proliferation inhibition action of adriamycin, and induce apoptosis which may result from the down-regulation of the anti-apoptotic bcl-2 protein.

Antifungal therapy for treatment of cryptococcal meningitis

OBJECTIVE

To compare the curative effects of three different antifungal regimens in the treatment of cryptococcal meningitis.

METHODS

Twenty-two patients were divided into 3 groups: Group I was given intravenous amphotericin B alone or combination with flucytosine therapy. Group II received intravenous fluconazole alone or combination with flucytosine. The treatment of Group III was divided into two steps, where the patients received intrathecal amphotericin B plus intravenous amphotericin B with or without intravenous fluconazole until the mycological culture of cerebrospinal fluid (CSF) turned negative, followed by oral fluconazole or itraconazole as maintenance therapy until direct microscopic examination of CSF showed negative once a week for three consecutive weeks.

RESULTS

Of the twenty-two patients, 17 (77.3%) were cured, 2 (9.1%) improved, 3 (13.6%) died, and one (4.5%) relapsed. Of the 8 patients in Group I, 5 were cured, 2 improved, one died and one relapsed; Of the 4 patients in Group II, 2 were cured, and 2 died; All the 10 patients in Group III were cured without any recurrence.

CONCLUSION

The two-step therapeutic regimen may be suited to the treatment of cryptococcal meningitis.

Risk factors for work-related low back pain in the People's Republic of China

A critical review was conducted of studies of work-related low back pain in the People's Republic of China. The published literature in both the English and Chinese languages from 1983 to 1997 was reviewed for studies that permitted the calculation of prevalence ratios. Thirty-five papers were identified initially, and after quality inclusion/exclusion criteria were applied, 16 (14 in Chinese and two in English) were selected for more detailed review. Prevalence ratios were statistically elevated in all but two of the selected studies. Prevalence ratios for individual groups ranged from 2.0 to 8.5 for bending and twisting, 1.5 to 14.3 for static posture, 1.9 to 5.5 for whole-body vibration, and 2.6 to 9.4 for low-temperature exposure. The literature was limited by the absence of standardized and robust measures of low-back-pain outcomes and exposures and by the omission of fundamental details from research reports. Even with these limitations, the review findings suggest that three physical risk factors, all well known in the international literature, are associated with the prevalence of low back pain in the People's Republic of China.

A comparison of 99Tcm-MIBI myocardial SPET and electron beam computed tomography in the assessment of coronary artery disease in two different age groups

The aim of this study was to compare the clinical value of 99Tcm-MIBI single photon emission tomography (SPET) and electron beam computed tomography (EBCT) in the assessment of coronary artery disease (CAD) in different age groups. 99Tcm-MIBI SPET (stress-rest), EBCT and coronary angiography studies were performed in 64 consecutive patients with suspected CAD. The patients were classified into two groups: Group A = 40 patients > 45 years of age and Group B = 24 patients < or = 45 years of age. There were 31 and 14 patients with coronary stenosis > or = 50% as determined by coronary angiography in Groups A and B, respectively. All patients (30 cases) with abnormal 99Tcm-MIBI myocardial SPET and coronary calcification detected by EBCT had significant coronary artery disease, and 93.3% of the patients with normal 99Tcm-MIBI SPET and normal EBCT had normal coronary angiography or < 50% lumen narrowing of the coronary arteries. In Group B, the sensitivity of SPET for detecting CAD was significantly higher than that of EBCT (92.9 vs 42.9%, P < 0.01); the specificity of SPET was comparable to that of EBCT. In Group A, there was no significant difference between SPET and EBCT in terms of sensitivity (93.6 vs 90.3%) or specificity (88.9 vs 55.6%). However, in the detection of individual coronary artery disease, the specificity of SPET was significantly higher than that of EBCT in Group A (94.1 vs 66.7%, P < 0.001). The sensitivity of SPET was again significantly higher than that of EBCT (85.7 vs 38.1%, P < 0.005) in Group B. The accuracy of SPET was higher than that of EBCT in both groups (82.5 vs 67.5%, P < 0.01 in Group A; 93.1 vs 76.4%, P < 0.01 in Group B, respectively). We conclude that 99Tcm-MIBI myocardial perfusion SPET has a higher sensitivity than EBCT in the detection of CAD in patients < or = 45 years old and a higher specificity in patients > 45 years of age. A combination of SPET and EBCT may assess CAD more accurately.

[Effect of tamoxifen on apoptosis and drug resistance of breast cancer cells in vitro]

OBJECTIVE

To study the effect of estradiol (E2) and tamoxifen (TAM) on the apoptosis regulatory genes (bax, bcl-2) and mdr-1 in MCF-7 cells.

METHODS

Immunohistochemistry, in situ hybridization were used to observe the changes in bax, bcl-2 and mdr-1 genes after treatment with E2 and TAM.

RESULTS

E2 had ability to increase the expression of bcl-2 and mdr-1 but TAM decrease the expression of both. Synthetic bax oligodeoxynucleotide (ODN) was used as probe to perform in situ hybridization. It was shown that bax mRNA in MCF-7 cells was down-regulated by E2 and up-regulated by TAM. Significant correlation between bcl-2 and mdr-1 was observed after TAM treatment of MCF-7 cells (P < 0.05).

CONCLUSION

TAM regulates cell apoptosis and inhibits development of drug-resistance of MCF-7 breast cancer.

Caspase-mediated cleavage and functional changes of hematopoietic progenitor kinase 1 (HPK1)

Activation of c-Jun N-terminal kinase (JNK) by Fas ligation is caspase-dependent, suggesting that caspases may regulate activators of the JNK pathway. Here, we report that an upstream activator of JNK, hematopoietic progenitor kinase 1 (HPK1), was cleaved during apoptosis. Cleavage of HPK1 was blocked by peptide inhibitors for caspases. HPK1 was efficiently processed by recombinant caspase 3 in vitro. A conserved caspase recognition site, DDVD (amino acids 382 - 385), was found in the HPK1 protein sequence. By testing HPK1 proteins with in vivo and in vitro cleavage assays, we showed that aspartic acid residue 385 is the target for caspases. HPK1 cleavage separated the amino N-terminal kinase domain from the carboxyl C-terminal regulatory domain, and enhanced HPK1 kinase activity. Unlike the full-length HPK1, the N-terminal cleaved product failed to bind adaptor molecules Grb2 (growth factor receptor-bound protein 2) and Crk (CT10 regulator of kinase). The C-terminal fragment, although having three proline-rich domains, bound to Grb2 and Crk less efficiently than the full-length HPK1 protein. Taken together, the cleavage of HPK1 by caspase profoundly changed its biochemical properties.

Role of reactive oxygen species in acetylcholine-induced preconditioning in cardiomyocytes

We examined the ability of ACh to mimic ischemic preconditioning in cardiomyocytes and the role of ATP-sensitive potassium (KATP) channels and mitochondrial reactive oxygen species (ROS) in mediating this effect. Chick embryonic ventricular myocytes were studied in a flow-through chamber while flow rate, pH, PO2, and PCO2 were controlled. Cell viability was quantified with propidium iodide (5 microM), and production of ROS was measured using 2', 7'-dichlorofluorescin diacetate. Data were expressed as means +/- SE. Preconditioning with 10 min of ischemia followed by 10 min of reoxygenation or 10 min of ACh (1 mM) followed by a drug-free period before 1 h of ischemia and 3 h of reoxygenation reduced cell death to the same extent [preconditioning 19 +/- 2% (n = 6, P < 0.05) ACh 21 +/- 5% (n = 6, P < 0.05) vs controls 42 +/- 5% (n = 9)]. Like preconditioning, ACh increased ROS production threefold before ischemia [0.60 +/- 0.16 (n = 7, P < 0.05) vs. controls, 0.16 +/- 0. 03 (n = 6); arbitrary units]. Protection and increased ROS production during ACh preconditioning were abolished with 5-hydroxydecanoate (5-HD, 100 microM), a selective mitochondrial K(ATP) channel antagonist, and the thiol reductant 2-mercaptopropionyl glycine (2-MPG, 1 mM), an antioxidant [cell death: 5-HD+ACh 37 +/- 7% (n = 5), 2-MPG+ACh 47 +/- 6% (n = 6); ROS signals: 5-HD+ACh 0.09 +/- 0.03 (n = 5), 2-MPG+ACh 0.01 +/- 0.04 (n = 4)]. In addition, ACh-induced ROS signaling was blocked by the mitochondrial site III electron transport inhibitor myxothiazol (0.02 +/- 0.07, n = 5). These results demonstrate that activation of mitochondrial K(ATP) channels and increased ROS production from mitochondria are important intracellular signals that participate in ACh-induced preconditioning in cardiomyocytes.

A novel src homology 3 domain-containing adaptor protein, HIP-55, that interacts with hematopoietic progenitor kinase 1

Hematopoietic progenitor kinase 1 (HPK1) is a member of the mitogen-activated protein kinase kinase kinase kinase (MAP4K) family and an upstream activator of the c-Jun N-terminal kinase (JNK) signaling cascade. HPK1 interacts, through its proline-rich domains, with growth factor receptor-bound 2 (Grb2), CT10-regulated kinase (Crk), and Crk-like (CrkL) adaptor proteins. We identified a novel HPK1-interacting protein of 55 kDa (HIP-55), similar to the mouse SH3P7 protein, containing an N-terminal actin-binding domain and a C-terminal Src homology 3 domain. We found that HPK1 bound to HIP-55 both in vitro and in vivo. When co-transfected, HIP-55 increased HPK1's kinase activity as well as JNK1's kinase activity. A dominant-negative HPK1 mutant blocked activation of JNK1 by HIP-55 showing that HIP-55 activates the JNK1 signaling pathway via HPK1. Our results identify a novel protein, HIP-55, that binds to HPK1 and regulates the JNK1 signaling cascade.

[A preliminary study on hepatitis E virus antibody IgG and IgM for the diagnosis of acute hepatitis E]

OBJECTIVE

To evaluate the significance of hepatitis E virus antibody (anti-HEV) IgG and IgM for the diagnosis of acute hepatitis E.

METHODS

Acute phase sera from a total of 143 patients with sporadic hepatitis E in 7 cities of China were determined for anti-HEV IgM and IgG by using an enzyme-linked immunosorbent assay (EIA). 359 serial sera of 56 patients with hepatitis E and 68 serial sera of 4 rhesus macaques experimentally infected with hepatitis E virus (HEV) were also detected for anti-HEV IgG and IgM.

RESULTS

In the 143 patients the positive rate of anti-HEV IgG was 100.0%, which was significantly higher than that of anti-HEV IgM (73.4%, 105/143). 97.2% of anti-HEV IgG positive patients had a titer over 1:40. The positive rate of anti-HEV IgM increased with the titer of anti-HEV IgG in sera. It was 0% (0/4), 44.4% (8/18) and 80.2% (97/121), respectively in patients with the anti-HEV IgG titer of 1:20, 1:40 and >or=1:80 (P < 0.001). All the anti-HEV IgM positive patients were also anti-HEV IgG positive. No patients were found to be anti-HEV IgM positive alone. Anti-HEV IgG was detected as early as 2 days after onset of the disease, with a cumulative positive seroconversion rate of 100% by 1 month. The negative seroconversion rate of anti-HEV IgG increased with course of the disease and 43.3% of the patients lost their anti-HEV IgG by 6 months after illness. Though anti-HEV IgM also seroconverted at the same time as anti-HEV IgG, its cumulative positive seroconversion rate was only 71.4% and declined rapidly. Up to 37.5% of anti-HEV IgM positive patients became negative by 1 month after onset. Similar antibody responses were observed in 4 rhesus macaques experimentally infected with HEV.

CONCLUSION

It is suggested that as a result of the poor sensitivity of currently available anti-HEV IgM EIA kits, anti-HEV IgG will be a more reliable marker for the diagnosis of acute hepatitis E as compared with anti-HEV IgM.

Mediation of TNF receptor-associated factor effector functions by apoptosis signal-regulating kinase-1 (ASK1)

Tumor necrosis factor-alpha (TNF), a major inflammatory cytokine, generates a wide variety of cellular responses via key cytoplasmic adaptor molecules named TNF receptor-associated factors (TRAFs). We report that TRAF2, TRAF5 and TRAF6 associate with apoptosis signal-regulating kinase 1 (ASK1), and a catalytically-inactive ASK1 mutant blocks stress-activated protein kinase (SAPK)/Jun NH2-terminal kinase (JNK) activation by these TRAFs. A truncated derivative of TRAF2, which inhibits SAPK activation by TNF, blocks TNF-induced ASK1 activation. Furthermore, protection from TNF-induced cell death conferred by an ASK1 mutant is dependent upon TRAF2. Hence, ASK1 is a common mediator of TRAF-regulated SAPK and apoptosis signaling, and the TRAF2 - ASK1 connection completes the signaling cascade from TNF to SAPK/JNK activation.

TANK potentiates tumor necrosis factor receptor-associated factor-mediated c-Jun N-terminal kinase/stress-activated protein kinase activation through the germinal center kinase pathway

Tumor necrosis factor (TNF) receptor-associated factors (TRAFs) are mediators of many members of the TNF receptor superfamily and can activate both the nuclear factor kappaB (NF-kappaB) and stress-activated protein kinase (SAPK; also known as c-Jun N-terminal kinase) signal transduction pathways. We previously described the involvement of a TRAF-interacting molecule, TRAF-associated NF-kappaB activator (TANK), in TRAF2-mediated NF-kappaB activation. Here we show that TANK synergized with TRAF2, TRAF5, and TRAF6 but not with TRAF3 in SAPK activation. TRAF2 and TANK individually formed weak interactions with germinal center kinase (GCK)-related kinase (GCKR). However, when coexpressed, they formed a strong complex with GCKR, thereby providing a potential mechanism for TRAF and TANK synergy in GCKR-mediated SAPK activation, which is important in TNF family receptor signaling. Our results also suggest that TANK can form potential intermolecular as well as intramolecular interactions between its amino terminus and carboxyl terminus. This study suggests that TANK is a regulatory molecule controlling the threshold of NF-kappaB and SAPK activities in response to activation of TNF receptors. In addition, CD40 activated endogenous GCKR in primary B cells, implicating GCK family proteins in CD40-mediated B-cell functions.

The activity of microsomal triglyceride transfer protein is essential for accumulation of triglyceride within microsomes in McA-RH7777 cells. A unified model for the assembly of very low density lipoproteins

Previously, based on distinct requirement of microsomal triglyceride transfer protein (MTP) and kinetics of triglyceride (TG) utilization, we concluded that assembly of very low density lipoproteins (VLDL) containing B48 or B100 was achieved through different paths (Wang, Y. , McLeod, R. S., and Yao, Z. (1997) J. Biol. Chem. 272, 12272-12278). To test if the apparent dual mechanisms were accounted for by apolipoprotein B (apoB) length, we studied VLDL assembly using transfected cells expressing various apoB forms (e.g. B64, B72, B80, and B100). For each apoB, enlargement of lipoprotein to form VLDL via bulk TG incorporation was induced by exogenous oleate, which could be blocked by MTP inhibitor BMS-197636 treatment. While particle enlargement was readily demonstrable by density ultracentrifugation for B64- and B72-VLDL, it was not obvious for B80- and B100-VLDL unless the VLDL was further resolved by cumulative rate flotation into VLDL(1) (S(f) > 100) and VLDL(2) (S(f) 20-100). BMS-197636 diminished B100 secretion in a dose-dependent manner (0.05-0.5 microM) and also blocked the particle enlargement from small to large B100-lipoproteins. These results yield a unified model that can accommodate VLDL assembly with all apoB forms, which invalidates our previous conclusion. To gain a better understanding of the MTP action, we examined the effect of BMS-197636 on lipid and apoB synthesis during VLDL assembly. While BMS-197636 (0.2 microM) entirely abolished B100-VLDL(1) assembly/secretion, it did not affect B100 translation or translocation across the microsomal membrane, nor did it affect TG synthesis and cell TG mass. However, BMS-197636 drastically decreased accumulation of [(3)H]glycerol-labeled TG and TG mass within microsomal lumen. The decreased TG accumulation was not a result of impaired B100-VLDL assembly, because in cells treated with brefeldin A (0.2 microgram/ml), the assembly of B100-VLDL was blocked yet lumenal TG accumulation was normal. Thus, MTP plays a role in facilitating accumulation of TG within microsomes, a prerequisite for the post-translational assembly of TG-enriched VLDL.

Drug delivery of anticancer agents: water soluble 4-poly (ethylene glycol) derivatives of the lignan, podophyllotoxin

This paper reports on the synthesis and in vivo oncolytic activity of a series of water-soluble acyl derivatives of polyethylene glycol (PEG) conjugated podophyllotoxin. Some analogs of the polymer conjugate showed significantly better activity in a murine leukemia model than native podophyllotoxin suspended in an intralipid emulsion. Additionally, when tested intravenously against a solid lung tumor (A549) model, some conjugated analogs were equivalent to the podophyllotoxin/intralipid emulsion, while those compounds demonstrating slower rates of plasma hydrolysis (in vitro) appeared to cause greater toxicity. There appeared to be an overall correlation between the in vivo antitumor activity of the conjugate and its rate of hydrolysis in vitro, with those showing faster release possessing greater antitumor activity. In conclusion, the solubilization and predictable release of podophyllotoxin from a PEG carrier was achieved and resulted in some derivatives demonstrating, at a minimum, equivalency with podophyllotoxin when administered on an equal molar basis. Further studies may be warranted to assess the PEG-conjugates pharmacokinetics and therapeutic indices in leukemic models.

[Study on polyphasic taxonomy of rhizobia isolated from Lespedeza species]

The diversity of rhizobia isolated from Lespedeza spp. was determined on the basis of numerical analysis of phenotypic characteristics, sodium dodecyl sulfate-polyacrylarmide gel electrophoresis (SDS-PAGE) of proteins, DNA-DNA homology and restriction fragment length polymorphism (RFLP) analysis of 16S-ribosomal DNA genes. According to numerical analysis of 125 phenotypic characteristics, strains were divided into two groups at a similarity level of 67%. Group I included all the fast-growing strains, group II included all the slow-growing strains. Above the similarity level of 80%, four subgroups could be further divided. Subgroup I was fast-growing rhizobia containing representative strain of Sinorhizobium saheli. Subgroup II, III, IV were slow-growing rhizobia. Subgroup II composed of strains isolated from Lespedeza cuneata in Beijing area and these isolates produced acid in medium containing mannitol. Subgroup III included type strain of Bradyrhizobium japonicum. The DNA G + C contents and DNA-DNA homology of the members of above four subgroups were determined. The subgroup I shared the same DNA homologous group with S. saheli, subgroup III belonged to B. japonicum, subgroup IV belonged to B. elkanii, subgroup II was an unique DNA homologous group which showed low level of DNA relatedness with other slow-growing rhizobia species. RFLP analysis of 16S rDNA genes verified that the subgroup II was a distinctive genealine and showed genetic variation within the strains in it.

[The effect of 1, 25 (OH)(2)D(3)on growth and apoptosis in breast cancer cell line MCF-7]

OBJECTIVE

To study the effect of 1, 25-dihydroxyvitamin D(3) [1, 25 (OH)(2)D(3)] on growth and apoptosis in breast cancer cell line MCF-7.

METHODS

We compared cell numbers by using MTT method, analyzed cell cycle and apoptosis percentage by flow cytometric, observed cellular structure and ultrastructure, determined quantitatively apoptosis cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and detected expression of bcl-2 protein by Western Blot.

RESULTS

Incubation with 1, 25 (OH)(2)D(3) 10(-7) mol/L, MCF-7 cells exhibited significant growth inhibition. Flow cytometric analysis indicated cell's G(0)/G(1) arrest along with increasing apoptotic peak and percentage. The action of cytotoxic drug Adr was strengthened. Western Blot showed that 1, 25 (OH)(2)D(3) could down-regulate bcl-2 protein expression.

CONCLUSIONS

1, 25 (OH)(2)D(3) could be a new hormone for the treatment of breast cancer.

[Measurement of retinal nerve fiber layer thickness of normal eyes with nerve fiber analyzer]

OBJECTIVE

To study the retinal nerve fiber layer thickness (RNFLT) of normal eye and the correlation with age.

METHODS

RNFLT of 198 cases of normal eyes were examined by using nerve fiber analyzer (NFA).

RESULTS

There were significant inverse linear correlation between the RNFLT and age (r = -0.46, P < 0.01). In the analysis by the quadrant, the RNFLT was correlated with age in the superior and inferior quadrant. The mean ratio of superior and inferior quadrant thickness (S/I) was 1.041.

CONCLUSION

NFA seems to be an useful tool to measure the RNFLT quantitatively. The RNFLT of normal eye is found to be decreased with age.

[Apoptosis increased by bcl-2 antisense ODN in MCF-7 cell line]

OBJECTIVE

To study the effects of bcl-2 antisense oligonucleotides (ODN) on the expression of bcl-2 and apoptosis in MCF-7 cell line.

METHODS

Artificially synthesized bcl-2 specific antisense OND was introduced into MCF-7 cells by gene pulser electroprotocol. Fluorescence microscope, electron microscope, immunocytochemical staining assay, and FCM were used to detect the effects on cell apoptosis, expressional level of bcl-2 protein and cell cycle after transfecting bcl-2 antisense ODN.

RESULTS

The number of apoptotic cells was increased and expression of bcl-2 protein was declined (P < 0.05). FCM showed that the number of G(0)-G(1) phase cells was decreased and the number of G(2)-M, S phase cells were increased.

CONCLUSIONS

The effective transient expression of bcl-2 antisense ODN can be obtained by gene pulser electroprotocol in MCF-7 cell, the function of bcl-2 gene was declined and the number of apoptotic cells was increased after transfecting bcl-2 antisense ODN. bcl-2 may be used as an useful target in tumor research.