VEGF-siRNA silencing induces apoptosis, inhibits proliferation and suppresses vasculogenic mimicry in osteosarcoma in vitro

AIM

To inhibit the gene expression of vascular endothelial growth factor (VEGF) with the RNA interference (RNAi) technique and explore its influence on the apoptosis, proliferation, vasculogenic mimicry of osteosarcoma in vitro.

METHODS

PSilencer-VEGF plasmid transfected into osteosarcoma cell line of MG63 was recombinated by gene cloning, and VEGF expression was examined by Western blotting after transfection. The biological features of transfected MG63 including proliferation, apoptosis and vasculogenic mimicry, were assessed by MTT assay, flowcytometer, annexin V-FITC/PI, light microscopy and HE staining.

RESULTS

The sequence of pSilencer-VEGF plasmid was confirmed by DNA sequencing. Sequence-specific siRNA targeting VEGF significantly decreases its expression in MG63 cells. Cell growth was inhibited and early apoptosis was induced compared with non-siRNA tansfected cells. Decreased VEGF expression was associated with reduced vasculogenic mimicry of MG63 cells.

CONCLUSIONS

VEGF gene might be closely related to the apoptosis and proliferation of osteosarcoma cells, and appears to be crucial for formation of vasculogenic mimicry in osteosarcoma. Inhibition of VEGF expression by sequence-specific siRNA may become a novel approach for the treatment of VEGF-enriched neoplasma such as osteosarcoma.

The p53-inducible apoptotic protein AMID is not required for normal development and tumor suppression

AMID is an apoptosis-inducing factor (AIF)-homologous and mitochondria-associated protein that has been implicated in caspase-independent apoptosis. Transcription of human AMID gene is upregulated by p53 and downregulated in tumors in comparison to their matched normal tissues, suggesting the possibility that AMID is involved in the downstream effects of p53. To investigate the physiological functions of AMID, we generated AMID-deficient mice by gene targeting. AMID-deficient mice are viable and fertile, develop normally and lack obvious phenotypic changes compared to wild-type mice up to 1 year old. AMID(-/-) mice up to 1 year old have no spontaneous tumors and show similar fibrosarcoma incidence after MCA inoculation compared to wild-type mice. AMID(-/-) embryonic fibroblasts exhibit normal proliferation but slightly increased resistance to genotoxin-induced growth arrest. These findings suggest that AMID is not required for normal development and p53-mediated tumor suppression.

N-GLUCURONIDATION OF THE PLATELET-DERIVED GROWTH FACTOR RECEPTOR TYROSINE KINASE INHIBITOR 6,7-(DIMETHOXY-2,4-DIHYDROINDENO[1,2-C]PYRAZOL-3-YL)-(3-FLUORO-PHENYL)-AMINE BY HUMAN UDP-GLUCURONOSYLTRANSFERASES

The potential cancer therapeutic agent, 6,7-(dimethoxy-2, 4-dihydroindeno[1,2-c]pyrazol-3-yl)-(3-fluoro-phenyl)-amine (JNJ-10198409), formed three N-glucuronides that were positively identified by liquid chromatography-tandem mass spectrometry and NMR as N-amine-glucuronide (Glu-A), 1-N-pyrazole-glucuronide (Glu-B), and 2-N-pyrazole-glucuronide (Glu-C). All three N-glucuronides were detected in rat liver microsomes, whereas only Glu-A and -B were found in monkey and human liver microsomes. In contrast to common glucuronides, Glu-B was completely resistant to beta-glucuronidase. Kinetic analyses revealed that glucuronidation of JNJ-10198409 in human liver microsomes exhibited atypical kinetics that may be described by a two-site binding model. For the high affinity binding, K(m) values were 1.2 and 5.0 microM, and V(max) values were 2002 and 2,403 nmol min(-1) mg(-1) for Glu-A and Glu-B, respectively. Kinetic constants of low affinity binding were not determined due to low solubility of the drug. Among the human UDP-glucuronosyltransferases (UGTs) tested, UGT1A9, 1A8, 1A7, and 1A4 were the most active isozymes to produce Glu-A; for the formation of Glu-B, UGT1A9 was the most active enzyme, followed by UGT1A3, 1A7, and 1A4. Glucuronidation of JNJ-10198409 by those UGT1A enzymes followed classic Michaelis-Menten kinetics. In contrast, no glucuronides were formed by all UGT2B isozymes tested, including UGT2B4, 2B7, 2B15, and 2B17. Collectively, these results suggested that glucuronidation of JNJ-10198409 in human liver microsomes is catalyzed by multiple UGT1A enzymes. Since UGT1A enzymes are widely expressed in various tissues, it is anticipated that both hepatic and extrahepatic glucuronidation will likely contribute to the elimination of the drug in humans. Additionally, conjugation at the nitrogens of the pyrazole ring represents a new structural moiety for UGT1A-mediated reactions.

Treatment of fulminant liver failure by transplantation of microencapsulated primary or immortalized xenogeneic hepatocytes

BACKGROUND

The aim of this study was to evaluate the in vitro and in vivo function of hepatocytes after immortalization, cryopreservation, encapsulation, and xenotransplantation into mice with fulminant liver failure (FLF).

METHODS

Rat and human hepatocytes were isolated by collagenase digestion. Human hepatocytes were immortalized using lentiviral vectors. Rat and immortalized human hepatocytes (IHH) were encapsulated in 400 microm of alginate-poly-L-lysine (PLL; Sigma, Buchs, Switzerland)-alginate membranes and cryopreserved using a computerized device. In vitro, encapsulated hepatocytes (cryopreserved or noncryopreserved) were cultured; albumin secretion was measured by enzyme-linked immunosorbent assay. Microencapsulated (cryopreserved or noncryopreserved) hepatocytes were transplanted intraperitoneally to mice with FLF: group 1 (n = 10) transplantation of empty capsules; group 2 (n = 12) transplantation of free primary rat hepatocytes; group 3 (n = 12) transplantation of cryopreserved encapsulated rat hepatocytes; group 4 (n = 10) transplantation of encapsulated rat hepatocytes; group 5 (n = 9) transplantation of cryopreserved encapsulated IHH; group 6 (n = 10) transplantation of encapsulated IHH.

RESULTS

Compared with free primary hepatocytes, cryopreserved or noncryopreserved encapsulated rodent hepatocytes showed similar levels of continuous in vitro albumin secretion over 1 week. Cryopreserved or noncryopreserved encapsulated IHH showed minimal albumin secretion compared with free primary human hepatocytes. Fulminant liver failure, produced by a combination of acetaminophen and 30% hepatectomy, resulted in a 20% to 30% host survival. In groups 1 and 2, survival was unmodified, compared with untreated mice. For groups 3 and 4, transplantation of cryopreserved or noncryopreserved encapsulated rat hepatocytes significantly increased survival rates to 66% and 80%, respectively (P < .01). For groups 5 and 6, transplantation of cryopreserved or noncryopreserved encapsulated IHH improved host survival to 50% and 55%, respectively (P < .05).

CONCLUSIONS

Primary rodent hepatocytes maintained synthetic functions after encapsulation and cryopreservation. Immortalized human hepatocytes showed minimal albumin secretion in the absence of encapsulation and cryopreservation, suggesting that hepatocytes lose some specific functions after immortalization. After induction of FLF in mice, intraperitoneal transplantation of encapsulated (primary or immortalized, cryopreserved or noncryopreserved) xenogeneic hepatocytes significantly improved survival. These results indicate that naive and genetically modified hepatocytes can be successfully encapsulated, stored by cryopreservation, and transplanted into xenogeneic recipients with FLF to sustain liver metabolic functions.

The effect of low carbohydrate on energy metabolism

OBJECTIVE

To investigate whether low-carbohydrate diets are efficient for reduction of body weight and through which mechanism.

DESIGN

A couple of studies using low-carbohydrate diets in the treatment of obesity are reviewed. Mechanisms for explaining the reduced appetite are described in relation to knowledge on regulation of appetite for fat and carbohydrate.

RESULTS

Studies with low-carbohydrate diets demonstrate a rapid weight loss, being more pronounced after 3 and 6 months compared to low-fat diets. After 12 months there is no difference between the low-carbohydrate and the conventional low-fat diet on weight loss. Both diets lead to improvements in risk factors for coronary heart disease, the low-carbohydrate diet leading to a greater decrease in serum triglycerides and increase in HDL cholesterol compared to the low-fat diet. Blood pressure, insulin sensitivity and LDL cholesterol were improved to a similar degree by the two diets. The mechanism for the rapid weight loss with the low-carbohydrate diet is a suppressed appetite, first through the high-protein content of the diet, second through the ketogenic nature of the diet with satiety signals for fat being active and third through the absence of hunger-promoting carbohydrate components like sucrose and/or fructose.

CONCLUSION

A rapid initial weight loss occurs with a low-carbohydrate diet due to a suppressed appetite. There is as yet no indication of an increased metabolic rate and an increased thermogenesis by the low-carbohydrate diet. The safety and efficacy of low-carbohydrate diets have to await further studies.

Role of CD40-CD154 pathway in the rejection of concordant and discordant xenogeneic islets

BACKGROUND

Costimulatory blockade has been shown to allow long-term survival of xenogeneic islets. The aim of the present study was to evaluate the role of recipient CD40 and CD154 in the rejection process of concordant and discordant islet xenotransplantation (Tx).

METHODS

Diabetic C57BL/6 mice, CD40- or CD154 knockout (KO) mice were transplanted with either concordant rat or discordant human islets.

EXPERIMENTAL DESIGN

group 1, control (ie, C57BL/6 mice received islet Tx without therapy); group 2, C57BL/6 mice received islet Tx with anti-CD154 monoclonal Ab (mAb) therapy; group 3, CD40 KO mice; and group 4, CD154 KO mice were used as recipients without therapy. Mouse anti-rat mixed lymphocyte reactions (MLR) were performed using mouse splenocytes obtained from animals transplanted with rat islets in groups 1 to 4.

RESULTS

In group 2, short-term anti-CD154 mAb therapy significantly prolonged rat-to-mouse and human-to-mouse xenograft survival, compared to controls. In CD40-KO and CD154-KO recipients, survival of concordant or discordant islets was not prolonged significantly compared to control groups. Mouse anti-donor rat cellular responses were reduced approximately 50% in group 2 but remained unmodified in groups 3 and 4, when compared to group 1.

CONCLUSIONS

Improved graft survival and reduced MLR responses against donor cells in vitro among the anti-CD154 mAb-treated mice could be explained by specific targeting of activated T cells with subsequent inactivation by anergy and/or elimination by apoptosis, or complement- or cellular-mediated mechanisms. Rejection of xenografts and strong MLR responses against donor cells in vitro in CD40 or CD154 KO animals is possible through efficient activation of alternate pathways of costimulation.

[Effect of artemether on nucleoside uptake and nucleic acid content in Schistosoma japonicum]

AIM

To observe the effect of artemether (Art) on nucleoside uptake and nucleic acid content in Schistosoma japonicum.

METHODS

RNA and DNA contents of both male and female worms harbored in mice treated intragastrically (i.g.) with Art 300 mg/kg for 24 h or 48 h were determined, respectively. After in vivo drug treatment, the schistosomes recovered were in vitro maintained in drug-free medium containing [3H]adenosine, [5-(3)H] uridine or [methyl-3H]thymidine at a final concentration of 37 MBq/L or 74 MBq/L for 2 h or 4 h, the tritiated nucleoside uptake and incorporation into nucleic acid of schistosomes were measured.

RESULTS

The RNA and DNA contents of female worms recovered from the host 48 h after dosing were markedly decreased by 51.6% and 23.5%, respectively, while the RNA content of male worms showed 42.4% reduction. When the above-mentioned schistosomes were in vitro exposed to the tritiated nucleoside for 2 h or 4 h, apparent decrease in tritiated nucleoside uptake with reduction rates of 35.2%-50.1% was seen in female worms. The incorporation of [methyl-3H]thymidine into the female worm DNA 2 h after incubation was reduced by 71.4% while the incorporation of [3H]adenosine into the female worm RNA and DNA 4 h after incubation was reduced by 65.2% and 50.0%, respectively.

CONCLUSION

Art exhibited an apparent effect on the nucleic acid metabolism in schistosomes, especially in female worms.

Cell-permeable ceramides increase basal glucose incorporation into triacylglycerols but decrease the stimulation by insulin in 3T3-L1 adipocytes

OBJECTIVE

To investigate mechanisms for the regulation of glucose incorporation into triacylgycerols in adipocytes by ceramides, which mediate some actions of tumour necrosis factor-alpha (TNFalpha).

DESIGN

The effects of C(2)- and C(6)-ceramides (N-acetyl- and N-hexanoyl-sphingosines, respectively) on glucose uptake and incorporation into triacylglycerols and pathways of signal tansduction were measured in 3T3-L1 adipocytes.

RESULTS

C(6)-ceramide increased basal 2-deooxyglucose uptake but decreased insulin-stimulated uptake without changing the EC(50) for insulin. Incubating 3T3-L1 adipocytes from 2 to 24 h with C(2)-ceramide progressively increased glucose incorporation into the fatty acid and especially the glycerol moieties of triacylglycerol. These effects were accompanied by increased GLUT1 synthesis resulting from ceramide-induced activation phosphatidylinositol 3-kinase, ribosomal S6 kinase and mitogen-activated protein kinase. C(2)-ceramide also increased p21-activated kinase and protein kinase B activities. However, C(2)-ceramide decreased the insulin-stimulated component of these signalling pathways and also glucose incorporation into triacylglycerol after 2 h.

CONCLUSIONS

Cell-permeable ceramides can mimic some effects of TNFalpha in producing insulin resistance. However, ceramides also mediate long-term effects that enable 3T3 L1 adipocytes to take up glucose and store triacylglycerols in the absence of insulin. These observations help to explain part of the nature and consequence of TNFalpha-induced insulin resistance and the control of fat accumulation in adipocytes in insulin resistance and obesity.

In vitro and in vivo effect of levopraziquantel, dextropraziquantel versus racemic praziquantel on different developmental stages of Schistosoma japonicum

AIM

To compare the antischistosomal effect of racemic praziquantel (Pra) and its enantiomers, levopraziquantel (L-Pra) and dextropraziquantel (D-Pra), on different developmental stages of Schistosoma japonicum.

METHODS

The in vitro effects of the drugs were determined in different stages of schistosomes maintained in RPMI 1640 supplemented with 20% calf serum. In vivo study mice infected with schistosome cercariae were treated intragastrically (ig) with Pra, L-Pra or D-Pra at different intervals after infection. The efficacy of the drugs was evaluated by residual mean worm number.

RESULTS

Based on the degree of tegument damage induced by L-Pra, d28 and d35 schistosomes were most susceptible to L-Pra, while d14 schistosomules being least susceptible. At comparable concentrations of 0.1-1 g/ml, L-Pra was more active than Pra even when the concentration of L-Pra was reduced to one-half of the minimum effective concentration of Pra. At above-mentioned concentrations D-Pra exhibited no apparent in vitro effect on different stages of schistosomes. When infected mice were treated ig with L-Pra, Pra or D-Pra at a single dose of 300 mg/kg or 500 mg/kg, only the former two drugs showed apparent effect on d0, d21, d28 and d35 schistosomes and less or much less effect on d3, d7 and d14 schistosomules. D-Pra only exhibited a negligible effect on d35 adult schistosomes as compared with L-Pra and Pra. When mice infected with d35 adult schistosmes were treated ig with L-Pra 150 mg/kg, the efficacy was similar to that of mice treated with Pra 300 mg/kg.

CONCLUSION

L-Pra is the principal active component against schistosomes in racemic Pra.

Comparative detection of measles and rubella IgM and IgG derived from filter paper blood and serum samples

We compared the use of serum and filter paper blood spots as specimen sources for the detection of measles- and rubella-specific IgM and IgG. We collected capillary blood into microtainer tubes and onto filter paper spots from 60 children and 60 healthy adults. The blood was collected from 12-15-month-old children approximately 3 weeks after primary vaccination with measles, mumps, rubella vaccine, and the sample-pairs were tested for measles-specific IgM and IgG antibodies by using a capture antibody EIA and an indirect EIA, respectively. We tested sample-pairs from a subset of participants for rubella- specific IgM and IgG antibodies by using commercially available capture IgM (Captia) and indirect IgG (Wampole) assays. The concordance of results from serum and filter paper blood spots was high for all assays: 98% for measles IgM, 93% for measles IgG, 94% for rubella IgM, and 93% for rubella IgG, and increased to between 96-100% for all four assays when indeterminate samples were excluded. The correlation coefficients for EIA signals were 0.99 and 0.77 for measles IgM and IgG, respectively, and 0.92 and 0.94 for rubella IgM and IgG, respectively. The cut-off values used for filter paper samples were the same as those used for serum samples for all tests except for the rubella IgM assay. The use of filter paper blood spots is a promising future option for the detection of measles- and rubella-specific antibodies.

High dietary phytoestrogen intake is associated with higher bone mineral density in postmenopausal but not premenopausal women

Animal studies demonstrated that phytoestrogen had a protective effect against bone loss after ovariectomy. However, data on dietary phytoestrogen intake as well as its relationship with bone mineral density (BMD) in human are not available. Six hundred fifty southern Chinese women, aged 19 to 86 yr, were recruited to determine their dietary phytoestrogen intake by a food frequency questionnaire. BMDs at the lumbar spine and hip region were measured using dual energy x-ray absorptiometry. The subjects were analyzed according to various tertiles of phytoestrogen intake. Among the postmenopausal women (n = 357), significant differences in the lumbar spine (L2-4) BMD (0.820 +/- 0.145 vs. 0.771 +/- 0.131 g/cm2, P < 0.05) and Ward's triangle BMD (0.450 +/- 0.151 vs. 0.415 +/- 0.142 g/cm2; P < 0.05) were found between the highest and lowest intake of isoflavone after adjusting for age, height, weight, years since menopause, smoking, alcohol consumption, HRT usage, and daily calcium intake. Women with the highest intake of isoflavone had significantly lower levels of serum PTH (19.38 +/- 14.61 vs. 26.56 +/- 11.19 pg/ml; P < 0.05), osteocalcin (4.95 +/- 3.61 vs. 6.69 +/- 5.05 mg/liter; P = 0.05), and urinary N-telopeptide (34.18 +/- 25.31 vs. 49.66 +/- 41.00 nmol bone collagen equivalents/mmol creatinine; P < 0.05) when compared with those with the lowest intake of isoflavone. No association between dietary phytoestrogen intake and BMDs was seen in the premenopausal women with high endogenous E (n = 293). In conclusion, postmenopausal women with habitually high intake of dietary isoflavone are associated with higher BMD values at both the spine and hip region. Customarily high isoflavone intake may help to reverse the state of secondary hyperparathyroidism associated with E withdrawal and hence lower the rate of bone turnover in postmenopausal women.

High dietary phytoestrogen intake is associated with higher bone mineral density in postmenopausal but not premenopausal women

Animal studies demonstrated that phytoestrogen had a protective effect against bone loss after ovariectomy. However, data on dietary phytoestrogen intake as well as its relationship with bone mineral density (BMD) in human are not available. Six hundred fifty southern Chinese women, aged 19 to 86 yr, were recruited to determine their dietary phytoestrogen intake by a food frequency questionnaire. BMDs at the lumbar spine and hip region were measured using dual energy x-ray absorptiometry. The subjects were analyzed according to various tertiles of phytoestrogen intake. Among the postmenopausal women (n = 357), significant differences in the lumbar spine (L2-4) BMD (0.820 +/- 0.145 vs. 0.771 +/- 0.131 g/cm2, P < 0.05) and Ward's triangle BMD (0.450 +/- 0.151 vs. 0.415 +/- 0.142 g/cm2; P < 0.05) were found between the highest and lowest intake of isoflavone after adjusting for age, height, weight, years since menopause, smoking, alcohol consumption, HRT usage, and daily calcium intake. Women with the highest intake of isoflavone had significantly lower levels of serum PTH (19.38 +/- 14.61 vs. 26.56 +/- 11.19 pg/ml; P < 0.05), osteocalcin (4.95 +/- 3.61 vs. 6.69 +/- 5.05 mg/liter; P = 0.05), and urinary N-telopeptide (34.18 +/- 25.31 vs. 49.66 +/- 41.00 nmol bone collagen equivalents/mmol creatinine; P < 0.05) when compared with those with the lowest intake of isoflavone. No association between dietary phytoestrogen intake and BMDs was seen in the premenopausal women with high endogenous E (n = 293). In conclusion, postmenopausal women with habitually high intake of dietary isoflavone are associated with higher BMD values at both the spine and hip region. Customarily high isoflavone intake may help to reverse the state of secondary hyperparathyroidism associated with E withdrawal and hence lower the rate of bone turnover in postmenopausal women.

Growth of infants during the first 18 months of life in urban and rural areas of southern China

OBJECTIVE

Observe the growth pattern of infants from birth to 18 months.

METHODOLOGY

A prospective study was conducted from 1994 to 1996 in urban and township-rural areas of Guangdong Province, southern China, recruiting 568 and 257 newborn infants, respectively. Anthropometric data was collected at birth, 1.5, 4, 5, 6, 8, 10, 12, 15, and 18 months.

RESULTS

The urban infants at birth had Z-scores of weight for age (WAZ), height for age (HAZ) and weight for height (WHZ) below the National Center for Health Statistics (NCHS) median (P < 0.01). However, from 1.5 to 4 months, the WAZ and WHZ scores were above (P < 0.01), but by 7 months fell and remained at - 0.7 to - 0.8 SD below the NCHS median (P < 0.01). HAZ scores improved after birth, were at the NCHS median to 8 months (P = NS), and then decreased to 0.2-0.4 SD below the NCHS median (P < 0.01). Compared with the urban infants, the township-rural infants were lighter and shorter throughout the first 18 months of life, and from 8 months of age, were - 1 SD or more below the NCHS median.

CONCLUSIONS

Growth retardation was found in this sample of Chinese infants. The magnitude of growth retardation was greater for infants in the township-rural area compared with those in the urban area.

Emerging areas of research reported during the CDC National Conference on Pfiesteria: from biology to public health

Since its identification in 1996, the marine dinoflagellate Pfiesteria piscicida Steidinger & Burkholder has been the focus of intense scientific inquiry in disciplines ranging from estuarine ecology to epidemiology and from molecular biology to public health. Despite these research efforts, the extent of human exposure and the degree of human illness directly associated with Pfiesteria is still in the process of being defined. Unfortunately, during this same time Pfiesteria has also stimulated media coverage that in some instances jumped ahead of the science to conclude that Pfiesteria presents a widespread threat to human health. Political and economic forces also came into play when the tourism and seafood industries were adversely impacted by rumors of toxin-laden water in estuaries along the east coast of the United States. Amid this climate of evolving science and public concern, Pfiesteria has emerged as a highly controversial public health issue. In October 2000 Centers for Disease Control and Prevention sponsored the National Conference on Pfiesteria: From Biology to Public Health to bring together Pfiesteria researchers from many disparate disciplines. The goal of this meeting was to describe the state of the science and identify directions for future research. In preparation for the conference an expert peer-review panel was commissioned to review the existing literature and identify research gaps; the summary of their review is published in this monograph. During the meeting primary Pfiesteria researchers presented previously unpublished results. The majority of those presentations are included as peer-reviewed articles in this monograph. The discussion portion of the conference focused upon researcher-identified research gaps. This article details the discussion segments of the conference and makes reference to the presentations as it describes emerging areas of Pfiesteria research.

Effect of combined treatment with praziquantel and artemether on Schistosoma japonicum and Schistosoma mansoni in experimentally infected animals

Praziquantel and artemether are safe and efficacious antischistosomal drugs that act against different developmental stages of the parasite: praziquantel against adult worms and artemether against schistosomula. A combined treatment has been suggested as a strategy for transmission control. Recent laboratory experiments with rabbits with a mixed infection of Schistosoma japonicum parasites of different ages confirmed the effectiveness of a combination therapy. In the present work, we assessed the effect of a combined treatment on adult worms of S. japonicum and found significantly higher worm reduction rates than with a single dose of praziquantel. In a next step, we extended the study of the combined treatment to Schistosoma mansoni. A combined treatment with 75 mg/kg praziquantel and 150 mg/kg artemether was administered to hamsters infected with juvenile and adult S. mansoni. The two drugs, administered simultaneously or spaced by 6 h, 1, 3 or 7 days, resulted in significantly higher worm reduction rates than a single treatment with praziquantel. A combination therapy with increased doses of 100 mg/kg praziquantel and 300 mg/kg artemether showed very high worm reduction rates of 90% and above, however, some hamsters died in five different combined treatment experiments, suggesting that these drug concentrations were too high. We conclude that a combined treatment with praziquantel and artemether at the lower doses is safe and more effective than praziquantel alone, which forms a foundation for designing respective clinical trials in humans.

Securin is not required for cellular viability, but is required for normal growth of mouse embryonic fibroblasts

Sister chromatid separation depends on the release of cohesion by the activity of Esp1, a member of the caspase family [1, 2]. In budding yeast, Esp1p is kept inactive by its association with Pds1p, until the onset of anaphase, when Pds1p is ubiquitinated by the APC/Cdc20 complex [3--5] and subsequently degraded by the 26S proteasome. Pds1 is not an essential gene in budding yeast, but is required for cell cycle arrest prior to anaphase in response to the disruption of spindle structures [6, 7]. Thus, Pds1 mutant yeast cells display precocious sister chromatid separation in the presence of nocodazole [6]. Mammalian orthologs of yeast Esp1 and Pds1, separin and securin, have been identified [8], and, as anticipated, a nondegradable mutant form of securin inhibits sister separation when added to mitotic Xenopus egg extracts [8]. Securin was also independently identified as PTTG (pituitary tumor transforming gene), a gene overexpressed in pituitary tumors [9]. The relationship between its overexpression in tumors and its control of sister chromatid cohesion remains ill defined. To explore securin function in mammals, we took a targeted gene disruption approach in mice. Here, we report that securin is neither essential for cell viability nor required for spindle checkpoint function, and mice lacking securin are viable and apparently normal, but mouse embryonic fibroblasts lacking securin grow abnormally in culture.

Molecular cloning and pharmacological characterization of the rat sigma1 receptor

In an effort to further understand the pharmacology of sigma receptors, we have cloned the rat homolog of the sigma1 receptor. We isolated a cDNA clone (rs2-2) from rat brain tissue using reverse transcriptase-polymerase chain reaction (RT-PCR) and 5' and 3' rapid amplification of cDNA ends (RACE) that encoded a full-length sequence of 223 amino acids. The predicted protein sequence of the clone has high homology with that of the murine (93.3%), guinea pig (93.7%), and human (96%) sigma1 receptors. Northern analysis showed a major mRNA band of approximately 1.8 kb. RT-PCR revealed the presence of the mRNA in all the tissues tested, with high levels in the brain, spinal cord, liver, thymus, adrenal glands, and kidneys. When expressed in Chinese hamster ovary (CHO) cells, the level of sigma1 binding increased markedly, and the binding profile was consistent with sigma1 sites. However, measurable levels of sigma1 binding present in the cell lines before transfection made the interpretation of these results difficult. To ensure that the binding reflected the transfected protein, we tagged the receptors with a hemagglutinin (HA) epitope at the amino terminus and examined binding in immunoprecipitated receptors. Western analysis using an antisera against the HA epitope revealed a molecular weight of approximately 28 kDa, close to the predicted value. The receptor binding profile of the immunopurified receptor was consistent with that seen with traditional sigma1 binding sites. Thus, rs2-2.HA encodes a high-affinity [3H](+)-pentazocine binding site with characteristics of a rat sigma1 receptor.

Effects of high-dose troglitaz one on insulin sensitivity and beta-cell function in Watanabe heritable hyperlipidemic rabbits

To clarify the dose-response effects of troglitazone on insulin sensitivity and beta-cell function, we examined the effects of high-dose troglitazone (100 mg/day per animal, administered as a food admixture) on glucose and insulin metabolism in hyperinsulinemic Watanabe heritable hyperlipidemic (WHHL) rabbits, and compared the results with our previous results with low-dose troglitazone (10 mg /day per animal).

MATERIALS AND METHODS

Glucose and insulin metabolism were quantitatively characterized by a minimal model technique as reported previously.

RESULTS

When troglitazone was administrated at a high dose for 6 months, it reduced hyperinsulinemia as reflected by a reduced basal (steady-state) insulin concentration lb and the insulin response to a glucose load, improved beta-cell function as reflected by decreased second-phase post-hepatic insulin delivery to glucose phi2, and reduced insulin resistance as reflected by increased insulin sensitivity to glucose disposal Si, without affecting glucose tolerance as reflected by an unchanged rate of glucose utilization Kg or insulin-independent glucose disposal Sg. The reductions in Ib and phi2 and the increases in Si in WHHL rabbits treated with a high dose of troglitazone were greater (p<0.05) than those observed in WHHL rabbits treated with a low dose of troglitazone, as assessed by a two-way repeated measures analysis of variance and the Wilcoxon-Mann-Whitney test.

CONCLUSION

In WHHL rabbits, troglitazone dose-dependently reduced hyperinsulinemia, improved beta-cell function, and increased insulin sensitivity.

[Comparison of seminal vitamin B12, folate, reactive oxygen species and various sperm parameters between fertile and infertile males]

Vitamin B12(VB12), folate and reactive oxygen species(ROS) in human semen from both fertile and infertile males, and their relationships with other parameters were observed. Semen samples from 44 infertile and 176 fentile control subjects were collected and measured based on the guidelines issued by WHO. The results showed that no significant differences on semen VB12 and folate were observed between fertile and infertile groups(P > 0.05). However, the levels of ROS in infertile group were significantly higher than those in fertile group(P < 0.01). The morphological defects and low motility of sperm in infertile group was significantly higher than those in fertile group(P < 0.01). A positive relation was observed between the levels of ROS production and the morphological defect of sperm(P < 0.01). There was a significant negative correlation between the levels of VB12, folate and ROS(P < 0.01) in semen. It is interesting to note that the values of ROS also show a significantly positive correlation with sperm motility (P < 0.01). A significant differences of ROS levels between fertile and infertile group with negative white blood cells in sperm was also observed. It is concluded that the increase of ROS on the morphological defect of sperm is one of the most important factors related to poor sperm quality and human infertility.

Artemether administered together with haemin damages schistosomes in vitro

We conducted experiments in vitro to assess the effect of artemether in combination with haemin on adult Schistosoma japonicum, S. mansoni and S. haematobium. When schistosomes were maintained in a medium containing artemether at concentrations of 20 micrograms/mL or less for 72 h, no apparent effect on the schistosomes was seen. When the medium contained 50 or 100 micrograms/mL haemin as well as artemether, the schistosomes showed decreased motor activity 2-24 h after exposure, which was followed by the staining of the whole worm body a reddish-yellow colour, dilatation of the intestine, and extensive vesiculation of the tegument. Some of the schistosomes died 24 h after exposure, and almost all died within 48-72 h. When schistosomes were exposed to the same concentrations of haemin alone, they were stained a light yellow colour but there was no apparent effect on their survival. Our findings suggest that artemether interacts with haemin to exert a toxic effect on the worms, which might be of importance in the further elucidation of the mechanism of action of artemether on schistosomes.

Behavioral training-induced c-Fos expression in the rat nucleus basalis of Meynert during aging

The present study investigated the behavioral training-induced c-Fos expression in the nucleus basalis of Meynert (nbM) in differently aged rats. This study demonstrated that the c-Fos expression in nbM was significantly increased and the peak occurred at 2 h after dark-avoidance training. Although the increase of c-Fos expression was also observed after pseudotraining, the number of Fos-like immunoreactive neurons in pseudotrained rats was significantly less than that in dark-avoidance trained rats at each time-point. This result suggested that c-Fos expression might be involved in learning and memory processes. In addition, all the pseudotraining-, training- and memory arousing-induced c-Fos expression was decreased with increasing age, and the decrease was more notable in trained and memory aroused rats. This suggested that the total number of nbM neurons and/or the sensitivity of nbM neurons to experimental manipulations, especially learning and memory performance, might reduce during aging.

[A Chinese herbal compound induces neurotrophy in astrocyte by a new study method called "cerebrospinal fluid pharmacology in Chinese materia medica"]

OBJECTIVE

To find a effective method by which the potency of Chinese materia medica (CMM) on the central nervous system (CNS) could be correctly investigated.

METHOD

The cerebrospinal fluid(CSF) and serum after oral CMM 1 to 1.5 hours was gained and then added into the astrocyte cell culture medium. After 48 h, the above medium was in proportion transferred to the neuron culture medium. Typan blue staining, LDH and MTT test were utilized to observe the drug effect on the neuron survival.

RESULTS

The serum, but not the CSF, showed the toxicity on the astrocyte. MTT test on the neuron survival showed that the OD492nm value in the CMM group was higher than the other groups (P < 0.05). The astrocyte medium stimulated by the CSF including CMM could promote the neuron axon growth.

CONCLUSION

If observing the CMM potency on CNS in vitro, the CSF was better than the serum, we called it "Cerebrospinal Fluid Pharmacology in Chinese Materia Medica". Furthermore, the CMM could induce the neurotrophy of astrocyte.

Effects of cholinergic agents on spontaneous activity of nucleus basalis magnocellularis neurons in different age rats

The present study investigated the effects of intracerebroventricular (i.c.v.) injection of acetylcholine (Ach), atropine and tubocurarine on the spontaneous activity of nucleus basalis Magnocellularis (nbM) neurons in young, adult and old rats. I.c.v. injection of Ach (1, 10 and 100 mM) dose-dependently increased the spontaneous firing rate in most of the nbM neurons (66.7%). The Ach-induced excitation effect on the spontaneous firing of nbM neurons was decreased with aging. I.c.v. injection of atropine (2.5, 25 and 250 mM) or tubocurarine (0.1, 1 and 10 mM) not only antagonized the Ach-induced excitation, but also inhibited the spontaneous firing of nbM neurons. The inhibitory effects were gradually decreased with aging. These results suggested that there might be some functional changes in nbM neurons with aging, which impair their responsive ability to stimuli of drugs.

[Effects of black and red rice on the formation of aortic plaques and blood lipids in rabbits]

In order to observe the antiatherosclerotic effects of black and red rice and to find out their mechanism, 24 New Zealand male white rabbits (average body weight 1.91 kg) were divided randomly into three groups (white rice, black rice and red rice groups). The rabbits were fed a cholesterol-enriched diet (cholesterol 5 g/kg, lard 35 g/kg) containing 300 g/kg white, black and red rice powder respectively. The rabbits were sacrificed 10 weeks later. The aorta was dissected and stained in 0.5% oilred-isopropanol solution. The plaque area and total area of aorta were measured by an automatic image analyzer. Serum lipids were determined by an automatic analyzer. The results showed that the plaque area (% of total surface) in the black and red rice groups was significantly lower than that in the white rice group (P < 0.05). Serum TG, TC, LDL-C, ApoB and ApoAI/ApoB were not significantly different among the three groups (P > 0.05). However, the concentrations of HDL-C and ApoAI were significantly higher in the black and red rice groups than those in the white groups (P < 0.05). No significant difference was found between the black and red rice groups. It is concluded that black and red rice might be effective in reducing atherosclerotic plaques on the aorta of rabbits fed a cholesterol-enriched diet. The effectiveness of black and red rice against atherosclerosis might be related to the high level of serum HDL-C and ApoAI.