[Performance of a novel combined flocculant HECES]

Combined flocculants with higher environmental safety and lower ecological risk are urgently required in the process of water and wastewater treatment. HECES, a kind of flocculants with high effect and high ecological safety was synthesized by natural and biodegradable polysaccharide starch of corn and inorganic aluminium salt. Flocculent performance includes sediment character and turbidity removal rate. The jar test results showed that the flocculent performance of HECES with the dose of 3.0 mg.L-1 was prior to the combined adding 4.5 mg.L-1 PAC and 1.0 mg.L-1 PAM in treating kaolin suspensions. The optimal concentration of HECES was 8.0 mg.L-1 and 4.0 mg.L-1 in treating domestic wastewater and municipal effluent respectively, with the comparison to 50% an 40% of PAC, the removal rate of turbidity reached 95% and 99%, respectively. It was also identified that the optimal concentration required to effect flocculation depended on kaolin concentration, and on the character of the wastewater within the range examined. It could be more effective to treat wastewater with higher concentration of HECES. The flocculating performance would be better at pH 4.0-9.5. The superior ecological safety of HECES was due to its lower dosage and its lower concentration of residual activated aluminium.

[Roles of rhizosphere in remediation of contaminated soils and its mechanisms]

Rhizosphere is a special 'ecological remediation unit' to treat contaminated soils, which contains a great quantity of microorganisms such as fungi and rhizobacteria living with plant roots. Thus, physiological and ecological roles of plant roots to remedy contaminated soils, to accumulate and to solidify heavy metals, to absorb and degrade organic pollutants in rhizosphere were illustrated, and the function of mycorrhizospheric fungi to absorb, barrier and chelate heavy metals, to degrade organic pollutants through their metabolism activities, the action of rhizobacteria to absorb and solidify heavy metals, to degrade organic pollutants in rhizosphere through their active living activities, and the combined remediation of fungi and bacteria to pollutants in rhizosphere and their relevant mechanisms were explained. It was suggested that the remediation role of rhizosphere was the main part of phytoremediation, and one of the main basic theories to remedy contaminated soils by the activity of green plants and other organisms. The use of hyperaccumulative plants in remedying soils contaminated by some heavy metals would be prospective. It would be one of the important approach to contaminated soils remediation by organic pollutants through the mechanism of screening some special plants whose roots had strong secreting ability to absorb and accumulate dissolvent organic pollutants on the basis of inoculating specific or non-specific fungi and bacteria from the rhizosphere. This will be a developing trend of research on the remediation of contaminated soils by organic pollutants.

[In vitro release kinetics and hypoglycemic effect on diabetic rats after oral administration of insulin loaded nanoparticles]

The insulin-loaded polyalkylcyanoacrylate nanoparticles (INS-NP) were made with Dextran 70 as the stabilizer. The mean diameter of INS-NP was 252.4 nm with a poly dispersity of 0.005. The associating ratio of insulin to the nanoparticles reached 70.1% +/- 2.3%, while the loading capacity was 0.14 u.mg-1. Studies on in vitro release kinetics showed that release profiles can be well modelled using a biexponential function. The burst effect was obvious, and a faster release was observed in acidic media. After various doses of INS-NP were intragastrically given to diabetic rats, significant decrease of glucose level was achieved in the 10 and 20 u.kg-1 groups, with no significant difference between these two doses. The relative bioavailability after p.o. administration of INS-NP 10 u.kg-1 over s.c. administration of insulin solution 1 u.kg-1 was 7.58% calculated by the area over the curve of glucose level (%) versus time profiles. The correlation was obvious between the % of insulin released at pH 7.0 and the % of glucose decreased within the first 7 hours. Hence, an oral insulin preparation with rather high bioavailability was provided in this study, and its shorter effective time will make it more convenient for the control of the glucose level in clinics.

Incidence of p53 and ras gene mutations in DMBA-induced rat leukemias

Leukemia, a form of haematological malignancy, is a multi-stage disease and a wide range of diverse genes has been speculated to correlate with its initiation and development. Ras has been speculated to be an initiating gene for haematological malignancy, but more investigation will be needed to determine the genes associated with the progression of the disease. 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat leukemia provides a good tool for research into various stages of the disease. The entire coding regions of p53 and ras genes were examined for mutations in the present study. In this experiment, we used fluorescence-labeled polymerase chain reaction single-stranded conformation polymorphism analysis (PCR-SSCP) and direct sequencing to detect mutations of both genes on rat erythroleukemia. Fifteen out of 18 (83.3%) rat leukemias were found to have N-ras codon 61 mutation, consistent with previous results. The result of direct sequencing showed a single base substitution (CAA to CTA), resulting in an amino-acid change from Gln to Leu. No mutations were found in H-ras, K-ras or codon 12 of N-ras. The incidence of p53 gene mutation was 16.6% (3/18) in rat leukemia at late-stage. In the present study, mutation of the p53 gene was detected in three DMBA-induced leukemias as follows: a single-base substitution (CAT to CGT) at codon 177 (exon 5), resulting in an amino-acid change from Arg to Leu, a CGG to CTG/CGG changed at codon 211 (exon 6) resulting in an amino-acid change from His to Arg/His, and a GGG to TGG at codon 242 (exon 6) resulting in an amino-acid change from Gly to Trp, respectively. Thus, mutations of p53 gene do not seem to respond to the carcinogenesis of the DMBA-induced leukemia, in contrast to mutation of the N-ras oncogene, and may possibly be involved in the progress of multi-stage leukemogenesis.

Stromal-derived factor-1 in human tumors recruits and alters the function of plasmacytoid precursor dendritic cells

Dendritic-cell (DC) trafficking and function in tumors is poorly characterized, with studies confined to myeloid DCs (DC1s). Tumors inhibit DC1 migration and function, likely hindering specific immunity. The role of plasmacytoid DCs (DC2s) in tumor immunity is unknown. We show here that malignant human ovarian epithelial tumor cells express very high levels of stromal-derived factor-1, which induces DC2 precursor (preDC2) chemotaxis and adhesion/transmigration, upregulates preDC2 very late antigen (VLA)-5, and protects preDC2s from tumor macrophage interleukin-10-induced apoptosis, all through CXC chemokine receptor-4. The VLA-5 ligand vascular-cell adhesion molecule-1 mediated preDC2 adhesion/transmigration. Tumor preDC2s induced significant T-cell interleukin-10 unrelated to preDC2 differentiation or activation state, and this contributed to poor T-cell activation. Myeloid precursor DCs (preDC1s) were not detected. Tumors may weaken immunity by attracting preDC2s and protecting them from the harsh microenvironment, and by altering preDC1 distribution.

Reciprocal regulation of plasmacytoid dendritic cells and monocytes during viral infection

Reciprocal regulation of opposing functions characterizes biological systems. We now show that adenovirus-infected plasmacytoid dendritic cells (PDC) inhibit monocyte to myeloid dendritic cell (MDC) differentiation and function, and that adenovirus-infected monocytes inhibit PDC type I interferon secretion. Adenovirus-infected PDC secreted IFN-alpha, beta and omega in an 86:2:1 ratio. PDC type I interferons inhibited MDC differentiation and function (reduced IL-12 secretion, IFN-gamma induction, MLR and CD40 expression, and increased CD1a(+)CD14(+) cells). Type I interferon receptor blocking antibody reversed all PDC effects, and recombinant IFN-alpha, beta or omega replicated all effects, except reduced CD40. Adenovirus-infected monocytes suppressed PDC type I interferon secretion, which was reversed with anti-IL-10 neutralizing antibodies. Exogenous IL-10 suppressed PDC type I interferon secretion without reducing PDC viability. Therefore, monocyte IL-10 regulates PDC type I interferon secretion, and PDC type I interferons inhibit MDC differentiation and function. Such reciprocal regulation of potentially opposing influences may help modulate anti-pathogen immunity.

Cloning and characterization of a p53-related protein kinase expressed in interleukin-2-activated cytotoxic T-cells, epithelial tumor cell lines, and the testes

A human protein kinase, p53-related protein kinase (PRPK), was cloned from an interleukin-2-activated cytotoxic T-cell subtraction library. PRPK appears to be a homologue of a growth-related yeast serine/threonine protein kinase, YGR262c. However, a complementation assay using YGR262c-disrupted yeast indicated that PRPK is not functionally identical to the yeast enzyme. PRPK expression was observed in interleukin-2-activated cytotoxic T-cells, some human epithelial tumor cell lines, and the testes. The intrinsic transcriptional activity of p53 was up-regulated by a transient transfection of PRPK to COS-7 cells. PRPK was shown to bind to p53 and to phosphorylate p53 at Ser-15. These results indicate that PRPK may play an important role in the cell cycle and cell apoptosis through phosphorylation of p53.

Differential MAP kinase activation and Na(+)/H(+) exchanger phosphorylation by H(2)O(2) in rat cardiac myocytes

Bursts in reactive oxygen species production are important mediators of contractile dysfunction during ischemia-reperfusion injury. Cellular mechanisms that mediate reactive oxygen species-induced changes in cardiac myocyte function have not been fully characterized. In the present study, H(2)O(2) (50 microM) decreased contractility of adult rat ventricular myocytes. H(2)O(2) caused a concentration- and time-dependent activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), p38, and c-Jun NH(2)-terminal kinase (JNK) mitogen-activated protein (MAP) kinases in adult rat ventricular myocytes. H(2)O(2) (50 microM) caused transient activation of ERK1/2 and p38 MAP kinase that was detected as early as 5 min, was maximal at 20 min (9.6 +/- 1.2- and 9.0 +/- 1.6-fold, respectively, vs. control), and returned to baseline at 60 min. JNK activation occurred more slowly (1.6 +/- 0.2-fold vs. control at 60 min) but was sustained at 3.5 h. The protein kinase C inhibitor chelerythrine completely blocked JNK activation and reduced ERK1/2 and p38 activation. The tyrosine kinase inhibitors genistein and PP-2 blocked JNK, but not ERK1/2 and p38, activation. H(2)O(2)-induced Na(+)/H(+) exchanger phosphorylation was blocked by the MAP kinase kinase inhibitor U-0126 (5 microM). These results demonstrate that H(2)O(2)-induced activation of MAP kinases may contribute to cardiac myocyte dysfunction during ischemia-reperfusion.

A membrane protein enriched in endoplasmic reticulum exit sites interacts with COPII

Although all mammalian COPII components have now been cloned, little is known of their interactions with other regulatory proteins involved in exit from the endoplasmic reticulum (ER). We report here that a mammalian protein (Yip1A) that is about 31% identical to S. cerevisiae and which interacts with and modulates COPII-mediated ER-Golgi transport. Yip1A transcripts are ubiquitously expressed. Transcripts of a related mammalian homologue, Yip1B, are found specifically in the heart. Indirect immunofluorescence microscopy revealed that Yip1A is localized to vesicular structures that are concentrated at the perinuclear region. The structures marked by Yip1A co-localized with Sec31A and Sec13, components of the COPII coat protein complex. Immunoelectron microscopy also showed that Yip1A co-localizes with Sec13 at ER exit sites. Overexpression of the hydrophilic N terminus of Yip1A arrests ER-Golgi transport of the vesicular stomatitis G protein and causes fragmentation and dispersion of the Golgi apparatus. A glutathione S-transferase fusion protein with the hydrophilic N terminus of Yip1A (GST-Yip1A) is able to bind to and deplete vital components from rat liver cytosol that is essential for in vitro vesicular stomatitis G transport. Peptide sequence analysis of cytosolic proteins that are specifically bound to GST-Yip1A revealed, among other proteins, mammalian COPII components Sec23 and Sec24. A highly conserved domain at the N terminus of Yip1A is required for Sec23/Sec24 interaction. Our results suggest that Yip1A is involved in the regulation of ER-Golgi traffic at the level of ER exit sites.

[The influence of somatostatin 14 on the proliferation of human retroocular fibroblasts]

OBJECTIVE

To elucidate the possible mechanism of Somatostatin 14 in the treatment of Graves' ophthalmopathy, thus providing laboratory data with the intent to underpin therapeutic developments.

METHODS

The human retro-ocular fibroblasts (HROFb) was cultured and MTT colorimetry assay was used to determine the proliferation of HROFb.

RESULTS

MTT colorimetry assay could precisely reflect the proliferation of HROFb. The absorbance was directly proportional to the numbers of the cells (r = 0.996, P < 0.001). Somatostatin 14 could enhance the cell proliferation percentage at lower levels (< 25 nmol/L) and inhibit that at higher levels (> 25 nmol/L). The cell proliferation correlated positively to Somatostatin 14 levels significantly (r = -0.9054, P < 0.001).

CONCLUSION

Somatostatin 14 has a dual effect on HROFb.