Tacrolimus population pharmacokinetics according to CYP3A5 genotype and clinical factors in Chinese adult kidney transplant recipients

WHAT IS KNOWN AND OBJECTIVES

Tacrolimus is characterized by a narrow therapeutic index and a considerable inter- and intraindividual pharmacokinetic variability. The aim of our study was to develop a population pharmacokinetic model of tacrolimus in adult kidney transplant of Chinese patients, identify factors especially CYP3A5*3 genetic polymorphism that explain variability, and determine dosage regimens.

METHODS

Pharmacogenomic data obtained from 83 Chinese kidney transplant patients treated with tacrolimus were determined using polymerase chain reaction-restriction fragment length polymorphism analysis. Trough blood concentration data were collected from all of the patients during the 12 months of post-transplantation days and were analysed using the nonlinear mixed-effects modelling program. After building the final model, 1000 bootstraps were performed to validate the final model.

RESULTS AND DISCUSSION

A one-compartment model with first-order absorption and elimination adequately described the pharmacokinetics of tacrolimus. In this study, we observed that POD, HCT and CYP3A5*3 genotype were determinant factors in CL/F and POD related with V/F of tacrolimus significantly. The final model with the clearance covariates was presented as: Cl/F=THETA(1)*EXP(THETA(4)*(83/POD))*(39.1/HCT)**THETA(5)*EXP(THETA(6)*CYP3A5), and the final model with the volume covariates was presented as: Vd/F=THETA(2)*POD**THETA(3). The Ka was fixed to 4.5 h^-1 .

WHAT IS NEW AND CONCLUSION

The HCT, CYP3A5*3 genetic polymorphism and POD contributed to the interindividual variability of oral tacrolimus in Chinese adult renal transplant patients.

[Efficacy of Coflex in the treatment of lumbar spondylolisthesis]

Objective: To study the clinical results of Coflex and lumbar posterior decompression and fusion in the treatment of lumbar degenerative spondylolisthesis at L(4-5). Methods: Thirty-eight patients with Grade Ⅰ degenerative spondylolisthesis, from January 2008 to December 2011 in Beijing Chaoyang Hospital, Capital Medical University were reviewed, and patients were divided into two groups by randomness. Group A was treated with Coflex and group B with pedicle instrumentation and interbody fusion. Fifteen patients were included in group A, and 23 patients were included in group B. In group A, the average age was (56.3±9.1) years. In group B, the average age was (58.2±11.2) years. The clinical results were evaluated by visual analogue scale (VAS) and Oswestry disability index (ODI). Slip distance (SD) was measured before and after surgery, and the changes of intervertebral angle at index level and adjacent level were also recorded. Results: The follow-up period was 36 to 68 months, with the average of (39±14) months in the both groups. The operation time and bleeding volume of patients in group A were significantly less than that of group B (P<0.05). In both groups, the difference of ODI and VAS before operation and postoperative follow-up were statistically significant (P<0.05). There was no significant difference between lumbar intervertebral angle and the sliding distance in group A at all time points. In the group B, there was a significant increase in the intervertebral angle and the sliding distance at L(3-4) and L(5)-S(1 )level after surgery, the difference at upper and below adjacent segment before and after surgery were statistically significant. Conclusions: Coflex interspinous dynamic stabilization system has same excellent clinical results as pedicle screw instrumentation and fusion surgery for the treatment of L(4-5) degenerative spondylolisthesis; no significant progression of spondylolisthesis been observed during more than 3 years follow-up, and no obvious adjacent segment degeneration has been found.

Analysis of the cytochrome c oxidase subunit II (COX2) gene in giant panda, Ailuropoda melanoleuca

The giant panda, Ailuropoda melanoleuca (Ursidae), has a unique bamboo-based diet; however, this low-energy intake has been sufficient to maintain the metabolic processes of this species since the fourth ice age. As mitochondria are the main sites for energy metabolism in animals, the protein-coding genes involved in mitochondrial respiratory chains, particularly cytochrome c oxidase subunit II (COX2), which is the rate-limiting enzyme in electron transfer, could play an important role in giant panda metabolism. Therefore, the present study aimed to isolate, sequence, and analyze the COX2 DNA from individuals kept at the Giant Panda Protection and Research Center, China, and compare these sequences with those of the other Ursidae family members. Multiple sequence alignment showed that the COX2 gene had three point mutations that defined three haplotypes, with 60% of the sequences corresponding to haplotype I. The neutrality tests revealed that the COX2 gene was conserved throughout evolution, and the maximum likelihood phylogenetic analysis, using homologous sequences from other Ursidae species, showed clustering of the COX2 sequences of giant pandas, suggesting that this gene evolved differently in them.

Cloning and characterization of the dehydration-responsive element-binding protein 2A gene in Eruca vesicaria subsp sativa

Eruca vesicaria subsp sativa is one of the most tolerant Cruciferae species to drought, and dehydration-responsive element-binding protein 2A (DREB2A) is involved in responses to salinity, heat, and particularly drought. In this study, a gene encoding EvDREB2A was cloned and characterized in E. vesicaria subsp sativa. The full-length EvDREB2A cDNA sequence contained a 388-bp 5'-untranslated region (UTR), a 348-bp 3'-UTR, and a 1002-bp open reading frame that encoded 334 amino acid residues. The theoretical isoelectric point of the EvDREB2A protein was 4.80 and the molecular weight was 37.64 kDa. The genomic sequence of EvDREB2A contained no introns. Analysis using SMART indicated that EvDREB2A contains a conserved AP2 domain, similar to other plant DREBs. Phylogenetic analysis revealed that EvDREB2A and DREB2As from Brassica rapa, Eutrema salsugineum, Arabidopsis thaliana, Arabidopsis lyrata, and Arachis hypogaea formed a small subgroup, which clustered with DREB2Bs from A. lyrata, A. thaliana, Camelina sativa, and B. rapa to form a larger subgroup. EvDREB2A is most closely related to B. rapa DREB2A, followed by DREB2As from E. salsugineum, A. thaliana, A. hypogaea, and A. lyrata. A quantitative real-time polymerase chain reaction indicated that EvDREB2A expression was highest in the leaves, followed by the roots and hypocotyls, and was lowest in the flower buds. EvDREB2A could be used to improve drought tolerance in crops.

Histidine-tryptophan-ketoglutarate solution decreases mortality and morbidity in high-risk patients with severe pulmonary arterial hypertension associated with complex congenital heart disease: an 11-year experience from a single institution

Cardioplegic reperfusion during a long term ischemic period interrupts cardiac surgery and also increases cellular edema due to repeated solution administration. We reviewed the clinical experiences on myocardial protection of a single perfusion with histidine-tryptophan-ketoglutarate (HTK) for high-risk patients with severe pulmonary arterial hypertension associated with complex congenital heart disease. This retrospective study included 101 high-risk patients undergoing arterial switch operation between March 2001 and July 2012. We divided the cohort into two groups: HTK group, myocardial protection was carried out with one single perfusion with HTK solution; and St group, myocardial protection with conventional St. Thomas' crystalloid cardioplegic solution. The duration of cardiopulmonary bypass did not differ between the two groups. The mortality, morbidity, ICU stay, post-operative hospitalization time, and number of transfusions in HTK group were lower than those in St group (P<0.05). Univariate and multivariate analysis showed that HTK is a statistically significant independent predictor of decreased early mortality and morbidity (P<0.05). In conclusion, HTK solution seems to be an effective and safe alternative to St. Thomas' solution for cardioplegic reperfusion in high-risk patients with complex congenital heart disease.

[Hydrogen peroxide induces oxidative stress and the mitochondrial pathway of apoptosis in RAT intestinal epithelial cells (IEC-6)]

In order to investigate the mechanism of apoptosis in rat intestinal epithelial cells (IEC-6) induced by hydrogen peroxide (H(2)O(2)), IEC-6 cells were subjected to 20 μmol/L H(2)O(2) and cell proliferation activity was determined using 3-(4,5-dimethyl-2-yl)-2,5-diphenyltetrazolium bromide. Cell morphology was observed by microscopy and cell apoptosis was detected by acridine orange and ethidium bromide staining and the portion of apoptotic cells was measured by flow cytometry. Genes and proteins related to cell apoptosis were detected by RT-PCR and Western blotting, and the mitochondrial membrane potential was evaluated by fluorescence probes.

RESULTS

Significant morphology damage was caused by exposure to H(2)O(2), and results showed that ROS generation significantly increased (P < 0.01). The activity of superoxide dismutase decreased significantly (P < 0.05), malondialdehyde content increased (P < 0.05), and expression of both catalase and glutathione peroxidase decreased significantly (P < 0.05) in the H(2)O(2) treatment group. Mitochondrion membrane potential was reduced, cytochrome released into the cytoplasm and caspase-9 and caspase-3 were significantly increased (P < 0.01) after treatment with H(2)O(2). Moreover, the ratio of Bax/Bcl-2 and apoptosis were significantly increased (P < 0.01) in the H(2)O(2) group. In conclusion, the present study indicated that the mitochondrial pathway plays a vital role in H(2)O(2) induced IEC-6 cell apoptosis.

[Relationship between interleukin-8 levels in expressed prostatic secretion and expressions of bFGF and Bcl-2 in benign prostatic hyperplasia]

OBJECTIVES

To investigate the relationship between interleukin-8 levels in expressed prostatic secretion and expressions of basic fibroblast growth factor (bFGF) and Bcl-2 in benign prostatic hyperplasia (BPH).

METHODS

A series of 50 consecutive patients diagnosed with BPH and scheduled for transurethral resection of the prostate (TURP) were included. Patients were divided into two groups, simple BPH and BPH with chronic prostatitis (CP). The grade of inflammatory changes in the prostate was then determined blindly by two experienced pathologists, according to the classification system. Expressed prostatic secretion (EPS) was collected right before TURP for IL-8 detection using ELISA kits. The resected prostatic tissue was harvested for immunohistochemistry to measure the expression of Bcl-2 and bFGF.

RESULTS

A total of 30 (60%) patients were confirmed to have prostatic histologic inflammation. The volume of the prostate in BPH with CP was obviously larger than that in simple BPH (P=0.022). The NIH chronic prostatitis symptom index (NIH-CPSI) and international prostate symptom score (IPSS) of BPH with CP were both higher than those of simple BPH (P<0.05). Significantly increased levels of IL-8 were observed in EPS obtained from BPH patients with CP (mean level, 43.29 ng/L), compared with patients with simple BPH (mean level, 36.90 ng/L) (P=0.003). The expression of Bcl-2 in BPH with CP (mean level, 6.17) increased significantly, compared with those in simple BPH (mean level, 2.45) (P=0.013). The expression of bFGF in BPH with CP (mean level, 7.57) also obviously elevated, compared with those in simple BPH (mean level, 5.05) (P=0.008). Correlation coefficients of IL-8 levels in EPS and expression of Bcl-2 or bFGF indicated that IL-8 had strong correlation with Bcl-2 and bFGF respectively both in simple BPH and BPH with CP (0<R<1, P<0.05).

CONCLUSIONS

IL-8, Bcl-2 and bFGF are significantly up-regulated in BPH with CP patients, compared with simple BPH patients. Inflammation might play an important role in the outcome and development of benign prostatic hyperplasia and makes it more severe.

Molecular cloning and evolutionary analysis of captive forest musk deer bitter taste receptor gene T2R16

Sensing bitter tastes is crucial for most animals because it can prevent them from ingesting harmful food. This process is mainly mediated by the bitter taste receptors (T2R) that are largely expressed in the taste buds. Previous studies have identified some T2R gene repertoires. Marked variation in repertoire size has been noted among species. However, research on T2Rs is still limited and the mechanisms underlying the evolution of vertebrate T2Rs remain poorly understood. In the present study, we analyzed the structure and features of the protein encoded by the forest musk deer (Moschus berezovskii) T2R16 and submitted the gene sequence to NCBI GenBank. The results showed that the full coding DNA sequence (CDS) of musk deer T2R16 (GenBank accession No. KP677279) was 906 bp, encoding 301 amino acids, which contained ATG start codon and TGA stop codon, with a calculated molecular weight of 35.03 kDa and an isoelectric point of 9.56. The T2R16 protein receptor had seven conserved transmembrane regions. Hydrophobicity analysis showed that most amino acid residues in T2R16 protein were hydrophobic, and the grand average of hydrophobicity (GRAVY) was 0.657. Phylogenetic analysis based on this gene revealed that forest musk deer had the closest association with sheep (Ovis aries), as compared to cow (Bos taurus), Tursiops truncatus, and other species, whereas it was genetically farthest from humans (Homo sapiens). We hope these results would complement the existing data on T2R16 and encourage further research in this respect.

Effect of different fibre sources on performance, carcass characteristics and gastrointestinal tract development of growing Greylag geese

1. The effects of different fibre sources on the growth performance, carcass characteristics and gastrointestinal tract development were studied in growing Greylag geese (Anser anser). 2. Four experimental diets were formulated with corn (maize) straw silage (CSS), steam-exploded corn (maize) straw, steam-exploded wheat straw, and steam-exploded rice straw as fibre sources. A total of 224 male Greylag geese at 28 d of age were randomly assigned to one of the 4 experimental diets. 3. The birds fed on the CSS diets had higher average daily feed intakes than those fed on the steam-exploded straws. However, the 4 treatments had similar average daily gain, which contributed to significant differences in feed conversion ratios. The different fibre sources had no significant effects on the carcass characteristics. 4. The CSS-fed birds had larger gizzards and lower relative length of the caeca than the other three groups. However, the relative weights and lengths of the other gut segments, the relative weights of major organs and the pH values of the gastrointestinal contents were similar between the 4 treatments. It was concluded that straw fibres with different physico-chemical properties exerted an effect on daily feed intake and gastrointestinal development, especially for the gizzard. The pretreatment of straw had a large effect on utilisation efficiency and animal performance. Steam explosion is a promising straw pretreatment for inclusion in diets for geese.

Expression patterns of melatonin receptors in chicken ovarian follicles affected by monochromatic light

Artificial illumination is an important exogenous factor in the control of many physiological and behavioral processes as well as an important environmental factor in the management of laying hens. Melatonin receptors are members of the G protein-coupled receptor family. The hormone melatonin is secreted primarily by the pineal gland, with highest levels occurring during the dark period of a circadian cycle. The aim of this study was to examine the effect of monochromatic light on chicken egg reproduction and expression of melatonin receptors in chicken ovarian follicles. A total of 552 19-week-old hens were randomly divided into 4 groups with 138 birds in each group. Each group was randomly divided into 3 replicates with 46 birds in each replicate. Feed and water were provided for ad libitum. Light treatments were: control cool white (400-760 nm), blue (480 nm), green (560 nm), and red (660 nm). The short wavelength (blue light) group produced a greater total number of eggs at 300 days of age than did the long wavelength (red light) group, and the red light group showed higher melatonin receptor type 1A and melatonin receptor type 1C mRNA and protein expression. These results suggest that the wavelength of light is closely related to chicken egg number at 300 days of age; there is no effect of monochromatic light on melatonin receptor type 1B.

Expression of β-defensins in intestines of chickens injected with vitamin D3 and lipopolysaccharide

The objective of this study was to evaluate the effect of vitamin D3 (VD3) on the regulation of chicken intestinal β-defensin genes under normal and lipopolysaccharides (LPS) conditions. Four treatment groups were used, including a negative control group, VD3-injection group, LPS-injection group, and both VD3-injection and LPS-injection group. At 4, 24, and 48 h post-injection, intestines were collected and RNA was isolated to measure the chicken β-defensin genes with putative vitamin D responsive elements using quantitative polymerase chain reaction. Expressions of all 7 chicken β-defensin genes was detectable in the intestines. Significant increases in GAL-6, -7 and -9 were found following LPS injection treatment at 4, 24, and 48 h post-injection, respectively, whereas VD3 injection did not affect the expression of any investigated genes under normal conditions. However, the expression of GAL-4, -5, -6, and -10 were synergistically upregulated by VD3 in combination with LPS. These results suggest that VD3 enhances the immune immunity during LPS challenge by inducing the expression of chicken β-defensin genes when birds are exposed to immune stressors.

Relaxor ferroelectricity and magnetoelectric coupling in ZnO-Co nanocomposite thin films: beyond multiferroic composites

ZnO-Co nanocomposite thin films are synthesized by combination of pulsed laser deposition of ZnO and Co ion implantation. Both superparamagnetism and relaxor ferroelectricity as well as magnetoelectric coupling in the nanocomposites have been demonstrated. The unexpected relaxor ferroelectricity is believed to be the result of the local lattice distortion induced by the incorporation of the Co nanoparticles. Magnetoelectric coupling can be attributed to the interaction between the electric dipole moments and the magnetic moments, which are both induced by the incorporation of Co. The introduced ZnO-Co nanocomposite thin films are different from conventional strain-mediated multiferroic composites.

[Analysis of typical mangrove spectral reflectance characteristics]

Acquisition of mangrove spectrum properties and detecting the sensitive bands provide technology basis for inverse modeling and estimation by remote sensing for various indexes of mangrove. The typical mangroves of Guangxi Shankou Mangrove Reserve were taken for study objects, the standard spectrum curves of Bruguiera gymnorrhiza (Linn.) Savigny, Rhizophora stylosa, Kandelia candel, Avicennia marina, Aegiceras corniculatum, Spartina anglica and mudflat were gained by denoising analysis of field-measured spectrum curves acquired by ASD FieldSpec 2. Analyzing the spectral characteristics and their differences, the authors found that the spectrum curves for various kinds of mangrove are coincident, the bands that appeared with reflection peaks and reflection valleys are basically identical, the within-class differentiated characteristics are comparatively small, the spectrum characteristics of mangroves are obviously different with Spartina anglica and mudflat. In order to gain the quantitative description for within-class differentiated characteristics of mangrove, space distance method, correlation coefficient method and spectral angle mapping method were used to calculate the within-class differentiated characteristics. The division accuracy of correlation coefficient method is higher than spectral angle mapping method which is higher than space distance method, and the result indicates that the spectrum differences of within-class mangrove and Spartina anglica are relatively small with correlation coefficients more than 0.995, and spectrum curve angle cosine values more than 0.95.

Genetic effect of the prolactin receptor gene on egg production traits in chickens

The identification and utilization of potential candidate genes with significant effects on economically important traits have become increasingly important in poultry breeding programs. The prolactin (PRLR) receptor is a specific receptor for prolactin, which is an anterior pituitary peptide hormone involved in various physiological activities and is essential for reproductive success. In chickens, the PRLR gene resides on the Z chromosome. We used a pooled DNA sequencing approach for identifying SNPs of the PRLR gene. Three hundred and nine-six Erlang Mountainous chicken hens were genotyped for six SNPs using PCR-SSCP and PCR-sequencing methods; the association with chicken egg production traits was studied using general linear model procedures. Three linked SNPs (G14952A, A14969C and G14984A) at the P1 locus, two linked SNPs (G17560A and T17626A) at the P2 locus, and one SNP (T20868C) at the P3 locus were identified. Eight haplotypes were reconstructed on the basis of the six SNPs. The general linear model analysis indicated that there were significant associations of certain genotypes and haplotypes with some egg production traits. We conclude that chicken PRLR gene polymorphisms are associated with egg production traits and have potential as molecular markers for chicken breeding.

Effects of hyperbaric oxygen on aggressive periodontitis and subgingival anaerobes in Chinese patients

OBJECTIVE

To investigate the effects of hyperbaric oxygen (HBO2) on aggressive periodontitis (AgP), and subgingival obligate anaerobes in Chinese patients.

MATERIALS AND METHODS

Sixty cases of Chinese patients with AgP were randomly divided into two groups -the HBO2 group (30 cases) and the control group (30 cases). Study teeth were divided into four groups -: the HBO2 therapy, the HBO2 + scaling scaling group, the scaling group and the control group. Subgingival anaerobic organisms were measured with anaerobic culture, and number of obligate anaerobes and facultative anaerobes and Bacteroides melaninogenicus was counted. Comparisons of changes in the clinical indices, and subgingival anaerobes were made between the groups.

RESULTS

Highly significant differences in gingival index (GI), probing depth (PD), attachment loss (AL), and Plaque index (PLI), and tooth odontoseisis (TO) were seen in the HBO2, the HBO2 + scaling and the scaling groups when compared with the control group (P<0.01). The number of subgingival anaerobes as well as the types of obligate anaerobes and facultative anaerobes and the number of Bacteroides melaninogenicus were reduced markedly in these three treatment groups. Highly statistical differences in clinical indices, subgingival anaerobe number and types of obligate anaerobes and facultative anaerobes and Bacteroides melaninogenicus were found when comparisons were made between the HBO2 + scaling and the HBO2 groups, as well as between the HBO2 + scaling and the scaling groups. Clinical follow-ups indicated that the GI, PD, AL, TO, PLI and subgingival anaerobes number of the three therapeutic groups were reduced more severely than the control group.

CONCLUSIONS

HBO2 had good therapeutic effects on Chinese patients with AgP. HBO2 therapy combined with scaling and root planing was the most beneficial in the treatment of AgP. The therapeutic effect of HBO2 on AgP is most likely through inhibition of the growth of subgingival anaerobes. Clinical follow-ups suggest that the effect could last more than 2 years.

Ventricular assist devices: pharmacological aspects of a mechanical therapy

Heart failure (HF) is a global epidemic that continues to cause significant morbidity and mortality despite advances in medical therapy. Ventricular assist device technology has emerged as a therapeutic option to bridge patients with end-stage HF to heart transplantation or as an alternative to transplantation in selected patients. In some patients, mechanical unloading induced by ventricular assist devices leads to improvement of myocardial function and a possibility of device removal. The implementation of this advanced technology requires multiple pharmacological interventions, both in the perioperative and long-term periods, in order to minimize potential complications and improve patient outcomes. We herein review the latest available evidence supporting the use of specific pharmacological interventions and current practices in the care of these patients: anticoagulation, bleeding management, pump thrombosis, infections, arrhythmias, right ventricular failure, hypertension, desensitization protocols, among others. Areas of uncertainty and ground for future research are also highlighted.

Surface nanocrystallization for bacterial control

Stainless steel is commonly used in indwelling medical devices, food preparation, and heavy industry. Bacteria display reduced adherence to nanocrystallized stainless steel. In this article, we present quantitative information on the surface adhesive force, surface electron work function, and bacterial adherence to surfaces of nanocrystallized stainless steel with differing grain sizes. Surface nanocrystallization was achieved by sandblasting followed by recovery treatment. The adhesive force of bacterial binding to nanocrystallized surfaces was measured using an atomic force microscope with a synthetic-peptide-coated AFM tip designed to mimic the bacterial binding site of Pseudomonas aeruginosa, a common pathogen known to form biofilms. The electron work function of the steel surfaces was measured, and bacterial binding assays were performed using subinoculated P. aeruginosa cultures. It was demonstrated that for nanograined steel surfaces, the adhesive force, peptide adherence, surface electron activity, and bacterial binding all decreased with decreasing grain size.

Immunomodulatory activities of a new pentapeptide (Bursopentin) from the chicken bursa of Fabricius

The bursa of Fabricius (BF) is a central immune organ in birds, and some peptides from chicken BF have demonstrated important immune functions. Here, a new 626.27 Da pentapeptide, Bursopentin (BP5, Cys-Lys-Arg-Val-Tyr) was isolated and purified by reverse-phase high-performance liquid chromatography. In this study, we examined the effects of BP5 on antigen-specific immune response in BALB/c mice sensitized with inactivated avian influenza virus (AIV) [A/Duck/Jiangsu/NJ08/05 (AIV H9N2 subtype)]. The results suggested that BP5 enhanced anti-hemagglutinin antibody (IgG, the isotypes IgG1 and IgG2a) production, induced both of Th1- (IL-2 and IFN-γ) and Th2-type (IL-4 and -10) cytokines, increased proliferations of splenic lymphocyte subsets CD4+ T cells (CD3+CD4+), CD8+ T cells (CD3+CD8+) and B cells, and enhanced cytotoxic T-lymphocyte activity of the activated splenocytes against NIH3T3 cells. The effects of BP5 on the proliferation of isolated T- and/or B-cell populations of BALB/c mice were assessed, and the data suggested that BP5 promoted spleen lymphocyte proliferation by activating B cells directly and T cells indirectly. Further analysis revealed that B-lymphocyte proliferation induced by BP5 is mediated by reactive oxygen species generated from thiol auto-oxidation of BP5. Furthermore, our data indicated that protein kinase C, mitogen-activated protein kinase, and nuclear factor kappa B are involved in the signal transductions during the BP5-induced B lymphocyte proliferation. This study indicates that BP5 could be a potential immunomodulator for future immuno-pharmacological use.

Behaviors of microtubules (MTs) driven by biological motors (dynein c) at collisions against micro-fabricated tracks and mts for potential nano-bio-machines

In vitro motility assays, where protein motors (attached to a surface) move protein filaments, have been used for investigating protein motors' functions. In recent decades, these assays are extended to explore potential applications of motor proteins as biological motors in nano-bio-machine development. Recent attempts include fabricating micrometer-scale tracks on the surface to confine and guide the flow of bio-filaments as a power transfer medium driven by the motor proteins. Understanding the interaction between bio-filaments and fabricated tracks as well as the mutual interaction between bio-filaments is of importance to the design of potential nano-bio-machines. In this study, we investigate the behaviors of a microtubule driven by axonemal dynein at the collision against another microtubule and micro-fabricated walls, respectively. Based on experimental observations, we propose a model to study possible mechanisms for the microtubule-microtubule and microtubule-wall interactions, which involve bumping force, bending moment and torque generation.

Emerging mechanisms of vascular stabilization

Neural guidance cues are essential for a growing axon to correctly course through the body and innervate target tissues. Interestingly, the vascular network follows a parallel trajectory along nerves, suggesting that guidance cues important for neural patterning may also be required for proper vascular patterning. However, while an axon arises from one cell, a blood vessel is composed of many endothelial cells. Recent evidence suggests that neural repulsive cues are usurped by multi-cellular blood vessels to ensure vascular stabilization cues. Additional clues into the signaling mechanisms that promote vascular stabilization are emerging from cerebral cavernous malformations, a disease characterized by headache, epilepsy, and stroke. Thus, neurobiology and neurology are providing insights into the concepts of vascular stability.

Genetic structure of Oryza rufipogon Griff. in China

Oryza rufipogon Griff. (common wild rice; CWR) is the ancestor of Asian cultivated rice (Oryza sativa L.). Investigation of the genetic structure and diversity of CWR in China will provide information about the origin of cultivated rice and the grain quality and yield. In this study, we used 36 simple sequence repeat (SSR) markers to assay 889 accessions, which were highly representative of whole germplasm in China. The analysis revealed a hierarchical genetic structure within CWR. First, CWR has diverged into two ecotypic populations, a south subtropical population (SSP) and a middle subtropical population (MSP), probably owing to natural selection by the different climates. The distribution of specific alleles and haplotypes indicated that Chinese CWR had both indica-like and japonica-like variations; the SSP was an indica-like type, whereas the MSP was more japonica-like. The SSP and MSP further diverged into five (HN, GD-GX1, GX2, FJ and YN) and two (JX-HuN1 and HuN2) geographical populations, respectively. The genetic data suggest the isolation by distance, although water systems also appear to play an important role in the formation of homogenous populations, and occasionally landscape was also involved. The population GD-GX1, which grew widely in Guangdong and Guangxi provinces, was the largest geographical population in China. It had a high level of genetic diversity (GD) and the closest genetic relationship with other inferred populations. The population HN, with the smallest SSR molecular weights and the highest level of GD, may be the most ancestral population.

Surface nanocrystallization of stainless steel for reduced biofilm adherence

Stainless steel is one of the most common metallic biomedical materials. For medical applications, its resistance to the adherence of biofilms is of importance to the elimination or minimization of bacterial infections. In this study, we demonstrate the effectiveness of a process combining surface nanocrystallization and thermal oxidation (or a recovery heat treatment in air) for reducing the biofilm's adherence to stainless steel. During this treatment, a target surface was sandblasted and the resultant dislocation cells in the surface layer were turned into nanosized grains by a subsequent recovery treatment in air. This process generated a more protective oxide film that blocked the electron exchange or reduced the surface activity more effectively. As a result, the biofilm's adherence to the treated surface was markedly minimized. A synthetic peptide was utilized as a substitute of biofilms to evaluate the adhesion between a treated steel surface and biofilms using an atomic force microscope (AFM) through measuring the adhesive force between the target surface and a peptide-coated AFM tip. It was shown that the adhesive force decreased with a decrease in the grain size of the steel. The corresponding surface electron work function (EWF) of the steel was also measured, which showed a trend of variation in EWF with the grain size, consistent with corresponding changes in the adhesive force.

[Comparison of the attachment and growth characteristics between human junctional epithelium and oral epithelium cells]

OBJECTIVE

To compare the attachment and growth characteristics between human junctional epithelium (JE) and oral epithelium cells.

METHODS

The healthy JE biopsies were derived from the human teeth extracted due to impaction or orthodontic purpose. Enzyme digestion was used to isolate JE cells, which were then cultured in DKGM. The co-culture model of JE cell-tooth slice was built up by adding 3 decalcification cementum slices (5 mm x 3 mm x 1 mm) into sterilized plate containing 1 ml of JE cells (5 x 10(8)/L), 21 slices all together,and incubated in an atmosphere containing 5% CO2 at 37 degrees C for 1-14 days. The attachment structure was observed under transmission electron microscope, and the OE cells was used as control.

RESULTS

The human JE cells were polymorphous in shape and CK19 positive, while OE cells were consisted of equal and closely packed epithelial-like cells in a paving stone arrangement, and CK19 was only strained in a few cells. There were a few cells in JE-slice when co-cultured for 1-3 days, and electron dense plaques on the JE cell surface of the attached slice were observed at 9 days, and 2-3 layer of JE cells and hemidesmosome-like structure formed within 11-14 days. There were more OE cells within 1-3 days, electron dense plaques appeared at 7 days, and stratified epithelium and hemidesmosome-like structure formed in OE-slice at 9 days.

CONCLUSIONS

The cultured JE cells were immature and lower differentiated epithelial cells which were different from OE cells. Under the same condition the growth and attachment of JE cells on the cementum slice surface were slower than that of OE cells. Their attachment strength needs further study.

Production of xylobiose from the autohydrolysis explosion liquor of corncob using Thermotoga maritima xylanase B (XynB) immobilized on nickel-chelated Eupergit C

In this study, a thermostable recombinant xylanase B (XynB) from Thermotoga maritima MSB8 was immobilized on nickel-chelated Eupergit C 250L. This immobilized XynB was then used to hydrolyze the autohydrolysis explosion liquor of corncob (AELC) in a packed-bed enzyme reactor for continuous production of xylooligosaccharides, especially xylobiose. When tested in batch hydrolysis of AELC, the immobilized XynB still retained its relative activity of 92.5% after 10 cycles of hydrolysis at 90 degrees C. The immobilized XynB retained 83.6% of its initial hydrolysis activity even after 168 h of hydrolysis reaction at 90 degrees C and demonstrated a half-life time of 577.6 h (24 days) for continuous hydrolysis. HPLC showed that xylobiose (49.8%) and xylose (22.6%) were the main hydrolysis products yielded during continuous hydrolysis. Xylobiose was adsorbed on an activated charcoal column and eluted with a linear gradient of 15% (v/v) ethanol to yield xylobiose with 84.7% of recovery. Also, the purity of xylobiose was up to 97.2% as determined by HPLC. Therefore, the immobilized XynB was suitable for the efficient production of xylobiose from AELC. This is the first report on the immobilization of xylanase for xylobiose production.