Impact of multi-walled carbon nanotubes on aquatic species

To understand the environmental impacts of carbon nanotubes (CNTs), the toxicity study was carried out with water-soluble multi-walled carbon nanotubes (MWCNTs) using zebrafish (Danio rerio) as a model system. Zebrafish embryos were treated with different concentrations of MWCNTs. Teratogenic effects were evaluated through changes in embryonic development after 24 hours post-fertilization (hpf), 48 hpf and 72 hpf. No observable effect concentration (NOEC) was at 40 microg/mL. Lowest effect concentration (LOEC) of MWCNTs which caused significant phenotypic defects in zebrafish embryo was 60 microg/mL. At concentration above 60 microg/mL, slimy mucus like coating was observed around the embryo. At high concentrations, MWCNTs was found to be involved in the apoptosis, delayed hatching and formation of abnormal spinal chords. Thus, the toxicity of multi-walled carbon nanotubes is concentration dependent.

Individually-addressable flip-chip AlInGaN micropixelated light emitting diode arrays with high continuous and nanosecond output power

Micropixelated blue (470 nm) and ultraviolet (370 nm) AlInGaN light emitting diode ('micro-LED') arrays have been fabricated in flip-chip format with different pixel diameters (72 microm and 30 microm at, respectively, 100 and 278 pixels/mm(2)). Each micro-LED pixel can be individually-addressed and the devices possess a specially designed n-common contact incorporated to ensure uniform current injection and consequently uniform light emission across the array. The flip-chip micro-LEDs show, per pixel, high continuous output intensity of up to 0.55 microW/microm(2) (55 W/cm(2)) at an injection current density of 10 kA/cm(2) and can sustain continuous injection current densities of up to 12 kA/cm(2) before breakdown. We also demonstrate that nanosecond pulsed output operation of these devices with per pixel onaxis average peak intensity up to 2.9 microW/microm(2) (corresponding to energy of 45pJ per 22ns optical pulse) can be achieved. We investigate the pertinent performance characteristics of these arrays for micro-projection applications, including the prospect of integrated optical pumping of organic semiconductor lasers.

RhoA prevents apoptosis during zebrafish embryogenesis through activation of Mek/Erk pathway

RhoA small GTPase, as a key regulator for actin cytoskeletal rearrangement, plays pivotal roles during morphogenesis, cytokinesis, phagocytosis and cell migration, but little is known about its signaling mechanism that controls cell survival in vivo. Using zebrafish as a model, we show that non-overlapping antisense morpholinos that block either translation or splicing of rhoA lead to extensive apoptosis during embryogenesis, resulting in overall reduction of body size and body length. These defects are associated with reduced activation of growth-promoting Erk and decreased expression of anti-apoptotic bcl-2. Moreover, ectopic expression of rhoA, Mek or BCL-2 mRNA rescues such phenotypes. Consistently, combined suppression of RhoA and Mek/Erk or Bcl-2 pathways by sub-optimal dose of rhoA morpholino and pharmacological inhibitors for either Mek (U0126) or Bcl-2 (HA 14-1) can induce developmental abnormalities and enhanced apoptosis, similar to those caused by effective RhoA knockdown. Furthermore, U0126 abrogates the rescue by RhoA and MEK but not BCL-2. In contrast, HA 14-1 effectively abolishes all functional rescues by RhoA, MEK or BCL-2, supporting that RhoA prevents apoptosis by activation of Mek/Erk pathway and requiring Bcl-2. These findings reveal an important genetic and functional relationship between RhoA with Mek/Erk and Bcl-2 for cell survival control during embryogenesis.

[Research on biocompatibility and in vivo degradation of biodegradable chest wall prosthesis materials in experimental animals]

OBJECTIVE

To evaluate the biocompatibility and in vivo degradation of novel chest wall prosthesis materials and provide some data for their clinical application.

METHODS

According to the standard for the biological evaluation of the medical devices, several tests were performed to evaluate the tissue toxic effects induced by polydioxanone (Group A), chitosan (Group B), and hydroxyapitite/collagen (Group C), which were tested as component materials of the chest wall prosthesis. In the hemolysis test, 0.2 ml of the anticoagulant rabbit blood was added to the component materials and the normal saline (negative control) and to the distilled water (positive control). Five samples were made in each group. Absorbency was measured and the hemolysis rate was determined. In the acute systemic toxicity test, 20 mice were randomly divided into 4 groups (Groups A, B and C, and the normal saline group, n=5). The leaching liquid (50 ml/kg) was injected through the caudal vein, which was observed at 24, 48 and 72 hours. In the pyrogen test, 12 rabbits were randomly divided into 4 groups (Groups A, B, C and the normal saline group, n=3) the leaching liquid(10 ml/kg) was injected through the ear vein, and the body temperature was recorded within 3 hours. In the in vivo degradable test, the component materials (10 mm x 10 mm) were implanted in 12 rabbits at 2, 4, 8, 12, 16 and 24 weeks, respectively, after operation. Two rabbits were sacrificed for the macroscopic and the microscopic examinations.

RESULTS

The chest wall component materials had no hemolytic reaction, no acute systemic toxicity, and no pyrogen reaction. The results demonstrated that the implanted materials had only a mild inflammatory reaction during the early days of the grafting, which subsided gradually. There was no tissue denaturation, necrosis or pathological hyperplasia when the prosthesis materials were degraded.

CONCLUSION

The degradable materials of the chest wall prosthesis have a good biocompatibility and a great biological safety though their surgical application still requires a further clinical research.

[The degradation performance of chitin short fiber reinforced polycaprolactone composite in vitro]

We have investigated the degradation of pure Polycaprolactone (PurePCL) and chitin short fiber reinforced Polycaprolactone composite (SFRP) in vitro in order to provide useful scientific basis for clinical application. PurePCL, SFRP and DL-PLA were immersed in 0.9% NaCL solution for periods of 2, 4, 8, 12, 16 and 24 weeks. Then pH values in immersing solution, weight loss and mechanical properties of tested materials were measured and SEM was used to study the change of the materials in the process of degradation. It was shown that the initial strength of SFRP was much higher than that of PurePCL. In the process of degradation of SFRP, the pH values maintained weak acid or remianed neutral. The rate of weight loss of SFRP was faster than that of PurePCL, but slower than that of DL-PLA. The strength and modulus of SFRP did not change much in 24 weeks, compared with the initial ones. In conclusion, the composites have excellent properties and may be optimal for clinical use in reconstruction of chest wall defects as well as in internal fixation of bone fracture.

Benzo(a)pyrene inhibits expression of inducible heat shock protein 70 in vascular endothelial cells

Benzo(a)pyrene (BaP), a ubiquitous environmental pollutant known to cause many diseases including atherosclerosis, induces a dose-dependent reduction in the levels of the inducible Hsp70. To explore the mechanism underlying the reduction of Hsp70, we measured the levels of Hsp70, cytoplasmic and nuclear heat shock factor 1 (HSF1) in porcine aortic endothelial cells using Western blot, and then further characterized the binding ability of HSF1 and heat shock element (HSE) by electrophoretic mobility shift assay. We found that when porcine aortic endothelial cells were treated by 0.1-10 microM of BaP for 24 h, there was a significant reduction of Hsp70, cytoplasmic and nuclear HSF1 and the binding rate of HSF1 and HSE at 5, 10 microM of BaP but less effective at lower concentrations. The effect of BaP on the Hsp70 expression level was markedly attenuated by co-treatment with phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C (PKC). Staurosporine (STP), an inhibitor of PKC, blocked the effect of PMA treatment in combination with BaP. These results suggest that BaP might inhibit Hsp70 levels by reducing the expression of HSF1 and decreasing binding of HSF1 and HSE via PKC-dependent signaling pathways that might be involved in the regulation of Hsp70 gene expression under BaP.

Characterization and expression of a cDNA encoding a tubuliform silk protein of the golden web spider Nephila antipodiana

Spider silks are renowned for their excellent mechanical properties. Although several spider fibroin genes, mainly from dragline and capture silks, have been identified, there are still many members in the spider fibroin gene family remain uncharacterized. In this study, a novel silk cDNA clone from the golden web spider Nephila antipodiana was isolated. It is serine rich and contains two almost identical fragments with one varied gap region and one conserved spider fibroin-like C-terminal domain. Both in situ hybridization and immunoblot analyses have shown that it is specifically expressed in the tubuliform gland. Thus, it likely encodes the silk fibroin from the tubuliform gland, which supplies the main component of the inner egg case. Unlike other silk proteins, the protein encoded by the novel cDNA in water solution exhibits the characteristic of an alpha-helical protein, which implies the distinct property of the egg case silk, though the fiber of tubuliform silk is mainly composed of beta-sheet structure. Its sequence information facilitates elucidation of the evolutionary history of the araneoid fibroin genes.

Antitumor activities of the four sesquiterpene lactones from Elephantopus scaber L

AIM

To evaluate antitumor activity of sesquiterpene lactones (scabertopin (ES-2), isoscabertopin (ES-3), deoxyelephantopin (ES-4), isodeoxyelephantopin (ES-5)) isolated from Elephantopus scaber L. in vitro and in vivo.

METHODS

SMMC-7721, Caco-2 and HeLa cell lines were treated with ES-2,3,4,5. Cell viability was determined by MTT assay. Agarose gel electrophoresis was used to detect DNA fragmentation. To evaluate in vivo antitumor activity of ES-4, experimental murine tumor model was used.

RESULTS

It was shown that ES-2, ES-4, ES-5 exhibited significant antitumor effect in vitro in a concentration-dependent manner. However, the effect of ES-3 on the growth of tested cell lines was relatively weak. In HeLa cells exposed to ES-4 for 48 h, morphological changes and DNA ladder pattern evidencing on apoptosis were detected. ES-4 revealed in vivo antitumor activity.

CONCLUSION

Antitumor activity of studied sesquiterpene lactones may be due, at least in part, to induction of apoptosis in vitro. ES-4 possesses also antitumor activity in vivo.

[Preparation and biological evaluation of Chitin short fiber reinforced polycaprolactone composite]

Chitin short fiber reinforced polycaprolactone composite was prepared by melting blending method. The cytotoxicity and biocompatibility of pure polycaprolactone and of chitin short fiber reinforced polycaprolactone composite were investigated in order to provide useful scientific basis for clinical application. The biocompatibility of pure polycaprolactone and that of chitin short fiber reinforced polycaprolactone composite were evaluated by a series of tests, including cytotoxicity test in vitro, acute systemic toxicity test, hemolysis test, pyrogen test and sensitivity test. The results showed that the cytotoxicity scores of the two materials were grade 0 and the growth and proliferation of the cultured cells were not significantly inhibited by the two materials. There were no potential allergic materials in the composites and the maceration extract showed no hemolytic reaction, no acute systemic toxicity and no pyrogen reaction. We conclude that the composites have fine biocompatibility and are safe for clinical use in the reconstruction treatment for chest wall defect.

Bioremediation of contaminated surface water by immobilized Micrococcus roseus

The problems caused by contaminated surface water have gradually become more serious in recent years. Although various remediation technologies were investigated, unfortunately, no efficient method was developed. In this paper, a new bioremediation technology was studied using Micrococcus roseus, which was immobilized in porous spherical beads by an improved polyvinyl alcohol (PVA) - sodium alginate (SA) embedding method. The experimental results indicated that COD removal rate could reach 64.7 % within 72 hours when immobilized M. roseus beads were used, which was ten times as high as that of free cells. The optimum inoculation rate of immobilized M. roseus beads was 10 % (mass percent of the beads in water sample, g g(-1)). Suitable aeration was proved necessary to enhance the bioremediation process. The immobilized cells had an excellent tolerance to pH and temperature changes, and were also more resistant to heavy metal stress compared with free cells. The immobilized M. roseus beads had an excellent regeneration capacity and could be reused after 180-day continuous usage. The Scanning Electronic Microscope (SEM) analysis showed that the bead microstructure was suitable for M. roseus growth, however, some defect structures should still be improved.

Effects of thyroid hormone on the development of immune system in zebrafish

Effects of thyroxine (T4) and methimazole (MMI) on the development of the zebrafish immune system were investigated using continuous immersion treatment experiments. The effects of the treatments on thymus development were determined using computer-aided thymus morphometric analyses on in situ hybridization serial sections of the thymus while the effects on immune-related gene expression levels were monitored using quantitative real-time PCR. The findings indicate that thymus development and thymopoiesis, as indicated by thymus size, thymus Rag-1-positive region, and TCRAC expression level, were affected by T4 and MMI-treatments. With the exception of Ikaros, MMI-treated fish has lower immune-related gene expression levels, although it is not certain whether the effect resulted indirectly from the concomitant growth-retardation and/or directly from an effect on lymphopoiesis itself. The findings were comparable with those in mammalian system, thus providing the first evidence that the thyroid relationship with thymus development and lymphopoiesis is likely to be conserved from fish to higher vertebrates. It suggests the possibility of using zebrafish as a model system to investigate the molecular mechanisms involved in thyroid hormone-dependent disorders in the immune system.

Synthesis and evaluation of a new series of peptide-based endothelin receptor antagonists

Novel peptide-based endothelin (ET) receptor antagonists were designed and synthesized in our laboratory. BQ-485, HIM-CO-Leu-d-Trp-d-Trp-OH, was selected as the leading compound. The primary structures of these new tripeptides were ABO-CO-Leu-d-Trp-d-AA(X)-OH. The introduction of unnatural aromatic amino acids into these tripeptides was useful in the structure-activity relationship studies. Among the 20 tripeptides, 16 of them showed high activities against the contraction of rat aortic smooth muscles induced by ET-1.

Development and maturation of the immune system in zebrafish, Danio rerio: a gene expression profiling, in situ hybridization and immunological study

The development and maturation of the immune system in zebrafish was investigated using immune-related gene expression profiling by quantitative real-time polymerase chain reaction, in situ hybridization (ISH), immunoglobulin (Ig) detection by immuno-affinity purification and Western blotting as well as immersion immunization experiments. Ikaros expression was first detected at 1 day post-fertilization (dpf) and thereafter increased gradually to more than two-fold between 28 and 42dpf before decreasing to less than the initial 1dpf expression level in adult fish (aged 105dpf). Recombination activating gene-1 (Rag-1) expression levels increased rapidly (by 10-fold) between 3 and 17dpf, reaching a maximum between 21 and 28dpf before decreasing gradually. However, in adult fish aged 105dpf, the expression level of Rag-1 had dropped markedly, and was equivalent to the expression level at 3dpf. T-cell receptor alpha constant region and immunoglobulin light chain constant region (IgLC) isotype-1, 2 and 3 mRNAs were detected at low levels by 3dpf and their expression levels increased steadily to the adult range between 4 and 6 weeks post-fertilization (wpf). Using tissue-section ISH, Rag-1 expression was detected in head kidney by 2wpf while IgLC-1, 2 and 3 were detected in the head kidney and the thymus by 3wpf onwards. Secreted Ig was only detectable using immuno-affinity purification and Western blotting by 4wpf. Humoral response to T-independent antigen (formalin-killed Aeromonas hydrophila) and T-dependent antigen (human gamma globulin) was observed in zebrafish immunized at 4 and 6wpf, respectively, indicating that immunocompetence was achieved. The findings reveal that the zebrafish immune system is morphologically and functionally mature by 4-6wpf.

[Differences in haemozoin production and pathogenicity between chloroquine-sensitive and chloroquine-resistant strains of Plasmodium berghei]

AIM

To better understand the differences in haemozoin formation and pathogenicity between chloroquine-sensitive(N) and chloroquine-resistant(RC) strains of Plasmodium berghei.

METHODS

IRC mice were grouped as follows: group Xba I (Normal control, NC), group II (control treated with chloroquine alone, CC), group III (mice infected with N strain), group IV (mice infected with RC strain, RC) and group V (mice infected with RC strain and treated with chloroquine, RCC). Morphologic features of the parasites, parasitaemia, histological and ultrastructural changes of livers among the groups were compared.

RESULTS

Severe damages of the hepatic cells of the N group including increased lysosomes and swollen and fused mitochondria were detected. On the contrary, the prominent features in liver section of the RC group were inflammatory cell (notably mononuclear) infiltration and Kupffer cell activation. Numerous trophozoites and schizonts were sequestrated in hepatic sinusoids and less degeneration of parenchymal cells was found except for some swollen and vacuolated mitochondria. Internal food vacuoles containing haemozoin were found in the parasites of the N group, whereas external food vacuoles without haemozoin granules were arranged in foamy appearance within the parasitized cell of the RC group.

CONCLUSION

P. berghei RC strain may modify the mode of ingestion and degradation of hemoglobin in the parasites, resulting in impeding haemozoin formation. The difference in virulence between the N and RC strain of P. berghei is probably attributed to the significant differences in the induction of immune response of the host.

Morphologic transformation of the thymus in developing zebrafish

The morphologic transformation of the developing zebrafish thymus from 1 week postfertilization (wpf) to 15 wpf is described. The thymus overall morphology changed from a small pouch-like shape at 1 wpf to a conical shape between 2 and 3 wpf before acquiring a more complex shape from 4 wpf onward. Rapid growth rate along the lateral axis at the region near the pharyngeal epithelium occurred between 1 and 2 wpf, whereas rapid growth rate along the dorsal-ventral axis occurred between 3 and 6 wpf. Expansion of thymocyte population beginning from 1 wpf became more evident by 2 to 3 wpf, as indicated by the apparent increase of different sizes of lymphocytes, recombination activating gene-1 (rag-1), and T-cell antigen receptor alpha chain constant region (TCRAC) -positive cells. Tissue section in situ hybridization (ISH) analysis with rag-1 probe reveals that cortex-medullary regionalization has begun between 1 and 2 wpf as rag-1 expression clearly demarcated the cortex, whereas the medulla was rag-1 negative. The presence of TCRAC-positive cells in the medulla by 2-3 wpf, suggests that the thymic selection processes had begun. The zebrafish thymus is morphologically mature by 3 wpf. Early signs of thymic involution were observed in zebrafish aged 15 wpf.

Green fluorescent protein (GFP) transgenic fish and their applications

The coupling of the GFP reporter system with the optical clarity of embryogenesis in model fish such as zebrafish and medaka is beginning to change the picture of transgenic fish study. Since the advent of first GFP transgenic fish in 1995, GFP transgenic fish technology have been quickly employed in many areas such as analyses of gene expression patterns and tissue/organ development, dissection of promoters/enhancers, cell lineage and axonal pathfinding, cellular localization of protein products, chimeric embryo and nuclear transplantation, cell sorting, etc. The GFP transgenic fish also have the potentials in analysis of upstream regulatory factors, mutagenesis screening and characterization, and promoter/enhancer trap. Our own studies indicate that GFP transgenic fish may become a new source of novel variety of ornamental fish. Efforts are also being made in our laboratory to turn GFP transgenic fish into biomonitoring organisms for surveillance of environmental pollution.

Modulation of abscisic acid signal transduction and biosynthesis by an Sm-like protein in Arabidopsis

The phytohormone abscisic acid (ABA) regulates plant growth and development as well as stress tolerance. The Arabidopsis sad1 (supersensitive to ABA and drought) mutation increases plant sensitivity to drought stress and ABA in seed germination, root growth, and the expression of some stress-responsive genes. sad1 plants are also defective in the positive feedback regulation of ABA biosynthesis genes by ABA and are impaired in drought stress induction of ABA biosynthesis. SAD1 encodes a polypeptide similar to multifunctional Sm-like snRNP proteins that are required for mRNA splicing, export, and degradation. These results suggest a critical role for mRNA metabolism in the control of ABA signaling as well as in the regulation of ABA homeostasis.

[Effects of glutamine on the intestinal failure in rats model of acute necrotizing pancreatitis]

OBJECTIVE

To determine the effects of glutamine (Gln) on the intestinal failure in rats with acute necrotizing pancreatitis (ANP) and its possible mechanisms.

METHODS

Fifty-four Sprague-Dawley rats were randomly divided into 3 groups: sham operation (SO, n = 18), ANP (n = 18), and ANP treated with Gln (ANP + Gln, n = 18). ANP model was induced by injection of 5% sodium taurocholate solution into bilo-pancreatic duct. The therapy was continuously given with amino acid solution by a mini-pump via a central intravenous line. In addition, the ANP + Gin group was received 3% Gln dipeptide solution (equal to 2% Gln) with a dosage of 0.5g x kg(-1) x d(-1). These groups were isocaloric and isonitrogenous. Bacterial cultures from pancreas, mesenteric lymph node (MLN), liver, spleen and ascites were done at 24, 48, 72 h after operation. Endotoxin level in portal vein was determined. Pathologic changes of intestinal mucosa were also studied. Apoptosis of intestinal mucosa was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method. Expressions of insulin-like growth factor 1 (IGF-1), Gln synthetase (GSase) and glutaminase (Glnase) mRNA were assayed by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

At 24, 48, 72h, the positive rate of bacterial culture and the endotoxin concentration were increased significantly in ANP group compared to the SO group (P < 0.05), while Gln could decrease them significantly. Pathologic study showed that the height of mucosal villous in ANP group was lower than that in SO group, indicating the intestinal mucosa became more atrophy. However, the height of mucosal villous in ANP + Gln group was no significantly difference compared to that in SO group, indicated Gln could preserve the mucosa well. Apoptotic index was increased in ANP group and decreased in Gln treated rats. Expressions of IGF-1, GSase, Glnase mRNA were down-regulated in ANP group, but were up-regulated in ANP + Gln group.

CONCLUSIONS

The intestinal barrier function was impaired in ANP. Gln could protect intestinal barrier function. This action was probably related to its enhancement of IGF-1, GSase and Glnase mRNA expressions and its inhibition of intestinal mucosal apoptosis.