Differentiation of stem cells: strategies for modifying surface biomaterials

Stem cells are a natural choice for cellular therapy because of their potential to differentiate into a variety of lineages, their capacity for self-renewal in the repair of damaged organs and tissues in vivo, and their ability to generate tissue constructs in vitro. Determining how to efficiently drive stem cell differentiation to a lineage of choice is critical for the success of cellular therapeutics. Many factors are involved in this process, the extracellular microenvironment playing a significant role in controlling cellular behavior. In recent years, researchers have focused on identifying a variety of biomaterials to provide a microenvironment that is conducive to stem cell growth and differentiation and that ultimately mimics the in vivo situation. Appropriate biomaterials support the cellular attachment, proliferation, and lineage-specific differentiation of stem cells. Tissue engineering approaches have been used to incorporate growth factors and morphogenetic factors-factors known to induce lineage commitment of stem cells-into cultures with scaffolding materials, including synthetic and naturally derived biomaterials. This review focuses on various strategies that have been used in stem cell expansion and examines modifications of natural and synthetic materials, as well as various culture conditions, for the maintenance and lineage-specific differentiation of embryonic and adult stem cells.

Spatial control of cells, peptide delivery and dynamic monitoring of cellular physiology with chitosan-assisted dual color quantum dot FRET peptides

Cell-based assays have become important tools in the pharmaceutical and biotechnology industries. However, observing and monitoring molecules in cells that mimic the physiological environment is often difficult. Dynamic processes not only increase the accuracy of simulations, but also improve our understanding of the function and regulation of molecules within cells. In this study we used chitosan as a multifunctional biomaterial for selective micropatterning of cells, peptide delivery and covalent bonding with quantum dots (QD) to decrease the cytotoxicity of QD. Our results demonstrate the efficacy of chitosan-QD-peptide-Alexa Fluor 488 in controlling the spread and spatial organization of cells. Cationic chitosan also provided an efficient delivery mechanism to live cells. We used the shift from green to red fluorescence of the chitosan dual color QD peptide to detect biological activity. This methodology has potential applications in high throughput screening of inhibitors and activators of biological mechanisms and pathways and for use in the pharmaceutical industry.

A randomized controlled trial comparing motivational interviewing in education to structured diabetes education in teens with type 1 diabetes

OBJECTIVE To compare motivational interviewing-based education (MI) and structured diabetes education (SDE) for improving A1C and psychosocial measures in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS This study was a 9-month randomized controlled trial comparing MI (n = 21) to SDE (n = 23). Interventions were at baseline (T0) and 3 months (T1), with A1C and psychosocial measures obtained at 6 months (T2) and 9 months (T3). RESULTS Over the 6 months of follow-up, the SDE group had lower adjusted mean A1C value (least squares mean 10.31, SE 0.32) than the MI group (least squares mean 11.35, SE 0.34) (P = 0.03, d = -0.66). There were no differences on any of the psychosocial measures. CONCLUSIONS SDE is effective at improving metabolic control in adolescents with type 1 diabetes. Diabetes educators were proficient in learning MI.

Stretched inverse opal colloid crystal substrates-induced orientation of fibroblast

Recently, there has been increasing interest in studying the interaction between mammalian cells and nanometer-sized structures. However, the effect of nanostructures on cell behavior, such as cell morphology and alignment, is still largely unknown. Inverse opal colloid crystal substrates, which can be stretched to produce nano-scale pore structures of different degrees of orientation, serve as a convenient model system to study the effect of nanotopography on cell morphology and cell alignment. In this work, we fabricated inverse opal colloidal crystal films that were either unstretched or stretched to three, four or six times their original length, producing pore structures of increasing degree of orientation. Human dermal fibroblast-fetal (HDF-f) cells were seeded and cultured on these four types of substrates. The results from fluorescence microscopy and scanning electron microscopy indicated that cells showed the highest degree of alignment when cultured on inverse opal colloid crystal films that were stretched the most (six times original length). The results also demonstrated that the orientation of nanostructures could affect both the morphology and growth direction of fibroblasts. The ability to control the direction of cell growth through the engineering of nanostructures could have important applications in tissue engineering, especially for tissues with anisotropic structures, such as cardiac muscle, blood vessel, tendon and ligament.

The effects of aging on the strength of surround suppression of receptive field of V1 cells in monkeys

The surround suppression of the receptive field is important for basic visual information processing, such as orientation specificity. To date, the effects of aging on the strength of surround suppression are not clear. To address this issue, we carried out extracellular single-unit studies of the receptive field properties of cells in the primary visual cortex (area V1) in young and old rhesus (Macaca mulatta) monkeys. When presented with the oriented central stimulus, we found that cells in old animals showed reduced orientation and direction selectivity compared with those in young animals. When presented with the oriented central stimulus together with the optimal surround stimulus, more selective cells {orientation bias (OB) >/=0.1; a bias of 0.1 is significant at the P<0.005 level} in animals of both ages showed reduced orientation selectivity compared with the experiment that presented only the oriented central stimulus. When presented with the optimal central stimulus together with the oriented surround stimulus, cells in old animals showed reduced orientation and direction selectivity compared with young animals. Moreover, broadly tuned cells (OB<0.1) in old animals exhibited significantly reduced suppression indices that quantified the strength of the surround suppression of the receptive field, when compared with those in young animals. These results suggest that aging may seriously affect the surround suppression of the receptive field of V1 cells. Thus, the decreased strength of surround suppression of the receptive field may be one possible reason for the decreased stimulus selectivity of V1 cells previously found in the senescent brain. This work will contribute to an understanding of the physiological mechanisms mediating surround suppression of the receptive field.

First Report of Root Rot Caused by Phytophthora sansomeana on Soybean in China

Phytophthora sansomeana E.M. Hansen & Reeser is a newly described species and infects Douglas-fir, alfalfa, and soybean (1). Soybean production is an important part of the local economy in Yili State in Xinjiang Uygur Autonomous Region, northwest China. Unfortunately since 2005, root and stem rot disease has emerged on a number of farms. To identify the causal agent, plant samples with symptoms, including whole plant wilting or yellowing and stunting, were collected from fields during 2005 and 2008. Tissue from the edges of stem lesions was placed on selective lima bean agar (LBA) at 20°C for 3 to 4 days (2,3). Four single zoospore isolates of Phytophthora were obtained and maintained on LBA or 10% V8 juice liquid medium for examination of morphological and physiological characteristics. The colonies on LBA were aerial and rosaceous. The isolates were homothallic, and oogonia and oospores were readily produced in culture after 7 days on LBA plates. Oogonia averaged 38 μm and oospore width ranged from 23 to 48 μm and averaged 31 μm. Antheridia were approximately 15 × 12 μm and predominantly amphigynous in V8 juice. Sporangia were terminal or paragynous on persistent sporangiophores, nonpapillate, ovoid to obpyriform, and measured 52 × 35 μm with an average length/breadth ratio of 1.5. Hyphal swellings were produced in V8 juice 2 days after inoculation. The optimum temperature for growth was approximately 25°C and none occurred at 0 or 35°C. The internal transcribed spacer (ITS) sequence of this Phytophthora species (GenBank FJ966880) agreed 100% with sequences of P. sansomeana isolates deposited in GenBank (GQ853880 and EU925375). Pathogenicity tests were performed by hypocotyl inoculation method (2) using isolate Yili71 and potted soybean cv. Williams. Plants were grown in a growth chamber for 10 days before inoculation in 16-cm-diameter pots (2). Plants were inoculated with 2- × 2-mm plugs of mycelium grown for 4 days on LBA at 25°C, the plugs were adhered to the sides of wounded lower hypocotyls. As controls, plants were inoculated with LBA agar plugs without mycelium (2). Inoculated plants were maintained in a growth chamber at approximately 25°C with a 10-h dark/14-h light cycle and 50% relative humidity and symptom development was monitored daily for 1 week. Wounded stems inoculated with mycelium developed water-soaked lesions, which were similar to those seen on naturally infected plants. A Phytophthora sp. was reisolated from the margins of expanding lesions on wounded stems. To our knowledge, this is the first report of P. sansomeana infection of soybean in China and the threat it may pose to soybean production is unclear. References: (1) E. M. Hansen et al. Mycologia 101:129. 2009. (2) Z. Y. Wang et al. Fungal Genet. Biol. 43:826, 2006. (3) X. B. Zheng. Methods in Phytophthora. Chinese Agriculture Press. Beijing, China, 1995.

Compact optical curvature sensor with a flexible microdisk laser on a polymer substrate

We demonstrate a chip-scale compact optical curvature sensor. It consists of a low threshold InGaAsP microdisk laser on a flexible polydimethylsiloxane polymer substrate. The curvature dependence of lasing wavelength was characterized by bending the cavity at different bending radii. The measurements showed that the lasing wavelength decreases monotonously with an increasing bending curvature. A good agreement between experiment and three-dimensional finite-difference time-domain simulation was also obtained. The sensitivity of the compact device to the bending curvature is -23.7 nm/mm from the experiment.

Opening of circumaxillary sutures by alternate rapid maxillary expansions and constrictions

OBJECTIVE

To analyze quantitatively the circumaxillary suture opening after alternate rapid maxillary expansions and constrictions (Alt-RAMEC).

MATERIALS AND METHODS

Twelve inbred cats were randomly grouped into two equal groups for 1 week of rapid maxillary expansion (RME) (1 mm/day) or 5 weeks of Alt-RAMEC (1 mm/day). At the end of the experiment, the craniofacial skeleton of each cat was harvested. Each circumaxillary suture was then probed at three sites with a 0.5-mm pointed periodontal probe. A smooth probing without penetration was an ineffective suture opening (<0.5 mm), while a probing with penetration was an effective suture opening (>0.5 mm). For each suture, the quantity of suture opening (%) was the effective suture opening/(effective + ineffective suture opening). The intergroup differences were analyzed by chi-square test (P < .05).

RESULTS

Five weeks of Alt-RAMEC opened the circumaxillary sutures significantly more than 1 week of RME. This affected the circumaxillary sutures running coronally and articulating directly to the maxilla (56.9% vs 36.1%, P < .001), the sutures running sagittally, but articulating indirectly to the maxilla (94.4% vs 64.8%, P < .001), and the sutures running coronally, but articulating indirectly to the maxilla (58.3% vs 33.3%, P < .01). The sutures running sagittally were opened significantly more (94.4%-100.0%) than those running coronally (56.9%-58.3%), no matter if they articulated directly or indirectly with the maxilla.

CONCLUSIONS

Alt-RAMEC opens both the sagittally and coronally running circumaxillary sutures quantitatively more than conventional RME. However, more than 5 weeks of Alt-RAMEC would be needed to increase the opening of the coronally running circumaxillary sutures. (

Molecular dynamics simulation of complex particles in three dimensions and the study of friction due to nonconvexity

We investigate the macroscopic properties of frictionless nonconvex particles using molecular dynamics. The calculations are based on a simple and efficient method to simulate complex-shaped interacting bodies. The particle shape is represented by Minkowski operators. A multicontact time-continuous interaction between bodies is derived using simple concepts of computational geometry. Three-dimensional simulations of hopper flow show that the nonconvexity of the particles strongly affects the jamming on granular flow. Also the model allows the representation of complex bodies with rough surfaces as in friction studies and the reproduction of a wide range of friction and dilatancy angles as in true triaxial tests.

Roles of mGluR5 in synaptic function and plasticity of the mouse thalamocortical pathway

The group I metabotropic glutamate receptor 5 (mGluR5) has been implicated in the development of cortical sensory maps. However, its precise roles in the synaptic function and plasticity of thalamocortical (TC) connections remain unknown. Here we first show that in mGluR5 knockout (KO) mice bred onto a C57BL6 background cytoarchitectonic differentiation into barrels is missing, but the representations for large whiskers are identifiable as clusters of TC afferents. The altered dendritic morphology of cortical layer IV spiny stellate neurons in mGluR5 KO mice implicates a role for mGluR5 in the dendritic morphogenesis of excitatory neurons. Next, in vivo single-unit recordings of whisker-evoked activity in mGluR5 KO adults demonstrated a preserved topographical organization of the whisker representation, but a significantly diminished temporal discrimination of center to surround whiskers in the responses of individual neurons. To evaluate synaptic function at TC synapses in mGluR5 KO mice, whole-cell voltage-clamp recording was conducted in acute TC brain slices prepared from postnatal day 4-11 mice. At mGluR5 KO TC synapses, N-methyl-D-aspartate (NMDA) currents decayed faster and synaptic strength was more easily reduced, but more difficult to strengthen by Hebbian-type pairing protocols, despite a normal developmental increase in alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated currents and presynaptic function. We have therefore demonstrated that mGluR5 is required for synaptic function/plasticity at TC synapses as barrels are forming, and we propose that these functional alterations at the TC synapse are the basis of the abnormal anatomical and functional development of the somatosensory cortex in the mGluR5 KO mouse.

Efficacy and Safety of Valsartan/Hydrochlorothiazide Fixed-dose Combination Compared with Amlodipine Monotherapy as First-line Therapy for Mild to Moderate Hypertension

This double-blind, active- and randomized-controlled study compared the efficacy and safety of a fixed-dose combination of valsartan/hydrochlorothiazide 80 mg/12.5 mg once daily ( n = 32) with amlodipine monotherapy 5 mg once daily ( n = 33) for 8 weeks in patients with mild to moderate hypertension. Non-inferiority of valsartan/hydrochlorothiazide to amlodipine was demonstrated by comparable reductions in sitting systolic blood pressure (SBP), sitting diastolic blood pressure (DBP), and daytime, night-time and 24-h SBP and DBP on ambulatory blood pressure monitoring. Between-group comparisons of adverse events and changes in laboratory parameters did not reach statistical significance, except for uric acid which showed a significant increase in the valsartan/hydrochlorothiazide group compared with the amlodipine group, but was still below the laboratory's upper limit of normal. In conclusion, the use of the fixed-dose combination of valsartan/hydrochlorothiazide 80 mg/12.5 mg once daily as a starting regimen in patients with mild to moderate hypertension was shown to have non-inferior efficacy and comparable safety for daily practice compared with amlodipine 5 mg once daily monotherapy.

Dielectric constants of multiwall carbon nanotubes from direct current to microwave frequencies

A cylindrical rod constructed from a uniform mixture of multiwall carbon nanotubes and alumina powders dissolved in paraffin was inserted in the center of a radio frequency cavity. The real and imaginary dielectric constants of carbon tubes at various frequencies were measured, respectively, from the resonant frequencies and the quality factors, by a resistance-inductance-cacitance (RLC) meter and a microwave network analyzer. The dielectric rod benefits the protection of the sample from adsorbing moisture and preventing the rod from filling with air, thus making accurate measurments. A tunable probe specifically designed for the field pattern of a TM010 mode is delineated to improve the microwave coupling of the dielectric microwave resonator. This refined design is expected to facilitate the measurement yielding a significant manner. The real and imaginary parts of the dielectric constant of carbon nanotubes increase and decrease, respectively as frequencies increase satisfactorily in complying with the description from the free electron Drude model.

Recycle of Alum recovered from water treatment sludge in chemically enhanced primary treatment

An investigation was made to study the feasibility of recovering the Alum from coagulation sludges and reusing it in chemically enhanced primary treatment (CEPT) process to make the CEPT more cost-effective and recover the resource (Alum) efficiently. The optimum condition and efficiency of the acidification method for Alum recovery from coagulation sludge were investigated in the test. The results show that when the recovery rate of Alum reaches its highest level, 84.5%, the reduction rate of sludge is 35.5%. It turns out that the capability of recovered coagulant to remove turbidity, UV(254) and COD are 96%, 46% and 53%, respectively. The results prove that the recovered coagulants could be used in CEPT and the efficiency of recovered coagulant to remove pollutants is similar to that of fresh coagulant. Although some substances will be enriched during recycle, they have little effect on the quality of treated wastewater. The experiments verify that it would be an advisable and cost-effective way to recover Alum from coagulation sludges in water treatment and chemical wastewater treatment, and it could be then recycled to CEPT as well as reduce sludge volume.

Flexible compact microdisk lasers on a polydimethylsiloxane (PDMS) substrate

Compact microdisk cavities were fabricated on a polydimethylsiloxane substrate. The lasing of the flexible compact cavity was achieved with a low threshold power. The whispering-gallery mode of the microdisk was also characterized with three-dimensional finite-difference time-domain simulation. The curvature dependence in output power and threshold was also demonstrated by bending the microdisk cavity.

Boy born after gender preselection following successive gestational androgen excess of maternal luteoma and female disorders of sex development

OBJECTIVE

To present male gender preselection after successive gestational hyperandrogenism and female pseudohermaphroditism by pregnancy luteomas.

DESIGN

Case report.

SETTING

University-based teaching hospital.

PATIENT(S)

We describe herein a gravida who presented two successive 46, XX disorders of sex development with apparent female genitalia with an enlarged clitoris due to maternal androgen excess from pregnancy luteoma. The maternal hyperandrogenemia returned to a normal level and bilateral luteoma regressed spontaneously postpartum. After gender preselection by Y-bearing spermatozoa for intrauterine insemination at the third gestation, a healthy boy was born in spite of the exaggerated maternal androgen production of pregnancy luteoma to avoid 46, XX disorders of sex development.

INTERVENTION(S)

Y-bearing spermatozoa for intrauterine insemination as male gender preselection.

MAIN OUTCOME MEASURE(S)

Boy born after gender preselection for intrauterine insemination and cesarean section.

RESULT(S)

Healthy boy born without disorder of sex development after antenatal maternal androgen excess of ovarian luteoma.

CONCLUSION(S)

Successive pregnancy luteomas associated with maternal hyperandrogenism may cause female disorders of sex development. Male preselection ameliorates the insult of external genitalia ambiguity by antenatal androgen excess in this matter of concern.

Effects of alginate coated on PLGA microspheres for delivery tetracycline hydrochloride to periodontal pockets

The effects of alginate coated on tetracycline (Tc) loaded poly (D, L-lactic-co-glycolic acid) (PLGA) microspheres fabricated by double emulsion solvent evaporation technique for local delivery to periodontal pocket were investigated. Alginate coated PLGA microspheres showed smoother surface but enlarged their particle sizes compared with those of uncoated ones. In addition, alginate coated microspheres enhanced Tc encapsulation efficiency (E.E.) from 11.5 +/- 0.5% of uncoated ones to 17.9 +/- 0.5%. Moreover, all of the coated PLGA microspheres even fabricated at different conditions could prolong Tc release from 9-12 days with 50% or higher in cumulative release of Tc compared with those of uncoated ones. The swelling ratios of PLGA microspheres for alginate coated or uncoated ones, one of the possible mechanisms for enhancing Tc release for the coated ones, were measured. The results showed that 20% or higher in swelling ratio for the coated microspheres at the earlier stage of hydration (e.g. < or = 24 h) could be an important factor to result in high Tc release compared to the uncoated ones. In conclusion, alginate coated Tc loaded PLGA microspheres could enhance Tc delivery to periodontal pocket by enhancing drug encapsulated efficiency, released quantities and sustained release period compared with uncoated ones.

First Report of Stalk Rot Caused by Phytophthora tentaculata on Aucklandia lappa in China

Phytophthora tentaculata causes root and stalk rot of Chrysanthemum spp., Delphinium ajacis, and Verbena spp. in nurseries in the Netherlands and Germany (2). In later years, P. tentaculata was isolated from Verbena hybrids (3) and lavender cotton (Santolina chamaecyparissus) in Spain (1). In August 2007, stalk rot symptoms were observed on Aucklandia lappa (Asteraceae), an economically important Chinese medicinal plant, in some fields in Yunnan Province of China. Small groups of infected plants were randomly distributed throughout the fields. Plants showing stalk rot and wilting died rapidly. Diseased tissues were cut into 10-mm pieces and plated onto Phytophthora selective medium, P₅ARP (2), to obtain the pure cultures. Seven isolates were obtained, and five isolates were grown on solidified LBA (60 g of lima bean powder and 15 g of agar per 10,000 ml of distilled water) and 10% V8 juice liquid medium for examination of morphological and physiological characteristics (4). The colony surface texture was uniform and formed sparse, loosely branched mycelium on LBA medium. Radial growth rate was 2 to 3 mm per day at 24°C on LBA. In water, relatively small swellings were formed at hyphal branches. Sporangia were spherical or ovoid to obpyriform and some were distorted and papillate with a narrow exit pore. Approximately 10% of the sporangia were caducous with a short pedicel. Sporangial dimensions were 28 to 47 (35) × 21 to 36 (29) μm, length/breadth ratio 1.2. Chlamydospores formed on LBA after 1 week and were terminal, spherical, thin walled, and 21 to 31 (27) μm in diameter. The isolates were homothallic. Oogonia abundantly formed on LBA and were 25 to 36 (31) μm in diameter. One or two paragynous antheridia (15 × 10 μm) were attached to the oogonia. Oospores were spherical, hyaline, aplerotic, and 20 to 32 (25) μm in diameter. The minimum temperature for mycelium growth was 8°C and maximum temperature was 34°C. The internal transcribed spacer (ITS) region was amplified and sequenced and agreed 100% with sequences of four P. tentaculata isolates deposited in GenBank (Accession Nos. AJ854302, AY881001, DQ335634, and AF266775). Pathogenicity was assessed by flooding three potted A. lappa plants with a 10⁴ ml^-1 zoospore suspension and incubating at 20 to 22°C. As controls, two potted A. lappa plants were flooded with deionized water. All three inoculated A. lappa plants exhibited stalk rot after 15 days, from which the pathogen was reisolated using selective medium, P₅ARP. Controls remained healthy 15 days after inoculation, To our knowledge, this is the first report of P. tetaculata H. Kroeber & R. Marwitz infection of A. lappa in China. We speculate that the pathogen might have been introduced from other countries on seeds. References: (1) L. A. Álvarez et al. Plant Dis. 90:523, 2006. (2) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) E. Moralejo et al. Plant Pathol. 53:806. 2004. (4) X. B. Zheng. Methods in Phytophthora. Chinese Agriculture Press, Beijing, China, 1995.

Fasting regulates the expression of adiponectin receptors in young growing pigs

Adiponectin is an adipocyte-derived hormone that can improve insulin sensitivity. Its functions in regulating glucose utilization and fatty acid metabolism in mammals are mediated by 2 subtypes of adiponectin receptors (AdipoR1 and AdipoR2). This study was conducted to determine the effect of fasting on the expression of adiponectin and its receptors. The expression of adiponectin was not affected in s.c. adipose tissue, but adiponectin expression increased in visceral adipose tissue after fasting. In contrast, expression of both AdipoR mRNA was increased in the liver and s.c. adipose tissue of 24-h-fasted pigs compared with fed pigs, but the mRNA in muscle and visceral adipose tissue was not affected by fasting. A third putative adiponectin receptor, T-cadherin, was cloned and the mRNA expression was determined. T-Cadherin has been recognized to act as a vascular adiponectin receptor in vascular endothelial and smooth muscle cells. Our data showed that the expression of T-cadherin was decreased in the muscle of fasted pigs, suggesting that the expression of T-cadherin can be regulated by feeding status. In summary, in young pigs, adiponectin mRNA was up-regulated by fasting in visceral, but not s.c., adipose tissue, whereas AdipoR1 and AdipoR2 mRNA were increased in s.c., but not visceral, adipose tissue. The adiponectin receptor, T-cadherin, was expressed in s.c. and visceral adipose tissue and in muscle, but only muscle mRNA expression was decreased by fasting.

Transient cerebral ischemia increases CA1 pyramidal neuron excitability

In human and experimental animals, the hippocampal CA1 region is one of the most vulnerable areas of the brain to ischemia. Pyramidal neurons in this region die 2-3 days after transient cerebral ischemia whereas other neurons in the same region remain intact. The mechanisms underlying the selective and delayed neuronal death are unclear. We tested the hypothesis that there is an increase in post-synaptic intrinsic excitability of CA1 pyramidal neurons after ischemia that exacerbates glutamatergic excitotoxicity. We performed whole-cell patch-clamp recordings in brain slices obtained 24 h after in vivo transient cerebral ischemia. We found that the input resistance and membrane time constant of the CA1 pyramidal neurons were significantly increased after ischemia, indicating an increase in neuronal excitability. This increase was associated with a decrease in voltage sag, suggesting a reduction of the hyperpolarization-activated non-selective cationic current (I(h)). Moreover, after blocking I(h) with ZD7288, the input resistance of the control neurons increased to that of the post-ischemia neurons, suggesting that a decrease in I(h) contributes to increased excitability after ischemia. Finally, when lamotrigine, an enhancer of dendritic I(h), was applied immediately after ischemia, there was a significant attenuation of CA1 cell loss. These data suggest that an increase in CA1 pyramidal neuron excitability after ischemia may exacerbate cell loss. Moreover, this dendritic channelopathy may be amenable to treatment.

Differential time-series expression of immune-related genes of Pacific white shrimp Litopenaeus vannamei in response to dietary inclusion of beta-1,3-glucan

Time-series changes in transcript abundance of nine genes encoding important immune proteins in haemocytes or hepatopancreas of Pacific white shrimp Litopenaeus vannamei fed daily in a 1-week feeding trial diets containing three levels (0%, 0.2% or 1%) of beta-1,3-glucan from Schizophyllum commune were quantified by real-time PCR. As a whole, the immune modulation elicited by beta-glucan is bimodal, one swift reaction of up- or down-regulation occurred within 24h and a delayed regulation was commenced as late as 3-7days. Haemocyanin, crustin, prophenoloxidase (proPO) and transglutaminase (TGase) did not respond to the glucan treatment. While penaeidin 3 (Litvan PEN3) was swiftly down-regulated (0-24h), lysozyme and cytosolic manganese superoxide dismutase (cMnSOD) were swiftly up-regulated (0-24h). In contrast, the two pattern recognition proteins (PRPs), beta-glucan binding protein-high density lipoprotein (BGBP-HDL) and lipopolysaccharide/beta-glucan binding protein (LGBP), showed a delayed up-regulation. Their expressions were not maximized until as late as 72h or 7days, respectively, which coincide with the initiation of reported immune enhancement (6-24days) of PO and SOD activity, phagocytosis and superoxide anion production in penaeid shrimp receiving glucan-containing diet. These immune responses could be the downstream effects of the two PRP gene up-regulation that predispose the shrimp to a state of high immune responsiveness. Increased dosage of beta-glucan from 2 to 10gkg(-1) diet did not affect the expressions of the genes, indicating the sufficiency of beta-glucan supplementation at 2gkg(-1) diet.

Bond cutting in Cs-doped tris(8-hydroxyquinoline) aluminium

A series of Cs 4d and Al 2p spectra associated with valence-band and cut-off spectra have been used to characterize the interaction between caesium and tris(8-hydroxyquinoline) aluminium (Alq(3)) molecules in a Cs-doped Alq(3) layer. The Cs 4d and Al 2p spectra were tuned to be very surface sensitive by selecting a photon energy of 120 eV at the National Synchrotron Radiation Research Center, Taiwan. A critical Cs concentration exists, above which a new Al 2p signal appears next to the Al 2p peak of Alq(3) in the lower binding-energy side. The Al 2p signal was analyzed and assigned as being contributed from a mixture of Alq(2), Alq and Al. Experimental data supported the observation that bond cutting of Alq(3) by the doped Cs atoms occurred at high Cs doping concentration.

Tissue expressions of nine genes important to immune defence of the Pacific white shrimp Litopenaeus vannamei

The tissue expressions of nine immune related genes in apparently healthy Pacific white shrimp Litopenaeus vannamei were analyzed by conventional RT-PCR, quantitative real time PCR (qPCR) and in situ hybridisation. The nine genes were beta-glucan binding protein-high density lipoprotein (BGBP-HDL), lipopolysaccharide-beta-glucan binding protein (LGBP), haemocyanin, prophenoloxidase (proPO), transglutaminase (TGase), crustins, penaeidins (PEN), cytosolic manganese superoxide dismutase (cMnSOD), and lysozyme. Transcripts of all nine genes were detected in all tissues with differential expression levels when examined by RT-PCR and qPCR. BGBP-HDL, LGBP and haemocyanin were mainly expressed in the hepatopancreas and their expressions levels were about 1/10-1/3 those of beta-actin. Their expressions in other tissues were relatively limited. ProPO, TGase, crustins, PEN-3, and lysozyme showed the highest levels of expression in haemocytes and the lowest in hepatopancreas. Their expression levels in the haemocytes were 3 (PEN-3) to 10(-2) (proPO) times those of beta-actin. In contrast to the other genes, cMnSOD showed higher expression levels in haemolymph related organ, stomach and muscle; and lower expression levels in haemocyte, migut, neural ganglion and hepatopancreas. When examined by in situ hybridisation, hepatopancreatic F cells were found to be the major cell type that produced transcripts of BGBP-HDL, LGBP and haemocyanin. On the other hand, circulatory haemocytes and haemocytes infiltrated in various tissues contributed to the expressions of proPO, TGase, crustins, PEN-3 and lysozyme. Both hepatopancreatic F cell and haemocyte generated cMnSOD transcripts. Using in situ hybridisation, the present study is the first to show the tissue distributions of BGBP-HDL, LGBP, haemocyanin, TGase, crustins and cMnSOD in healthy white shrimp. The present results provide a baseline data of physiological expressions for the genes that are important in immune activation and modulation in Pacific white shrimp and a guideline of tissue or organ sampling for effective gene expression analyses for future immunological studies.

Inhibitory effect of Melastoma candidum D. Don acetone extract on foodborne pathogenic bacteria survival in food products

Melastoma candidum D. Don, a Taiwanese folk medicinal plant, has high levels of antibacterial and bactericidal activity. Our aim was to determine whether and to what extent an acetone extract of this plant inhibits the growth of foodborne pathogenic bacteria. M. candidum acetone extract had marked inhibitory effect on test bacteria introduced into sliced pork, which was then stored at 4 degrees C. At the end of storage (day 12), the bacterial concentrations dropped by 1.59 to 2.91 log CFU/g compared with the control. In steamed rice stored at 30 degrees C, a 0.2% extract decreased initial (before storage) concentrations of Bacillus cereus from 2.01 log CFU/g to an undetectable level, which remained for at least 24 h. After 72 to 168 h of storage, test bacterial concentrations were reduced by 2.59 to 5.66 log CFU/g. In fresh noodles stored at 30 degrees C, both initial and final bacterial concentrations were decreased. At the end of storage (72 to 168 h), test bacteria concentrations were reduced by 1.85 to 2.88 log CFU/g. Overall, M. candidum acetone extract had an inhibitory effect on foodborne pathogenic bacteria in different food model systems.

Genetic analysis and molecular mapping of the avirulence gene PRE1, a gene for host-species specificity in the blast fungus Magnaporthe grisea

We analyzed host-species specificity of Magnaporthe grisea on rice using 110 F1 progeny derived from a cross between the Oryza isolate CH87 (pathogenic to rice) and the Digitaria isolate 6023 (pathogenic to crabgrass). To elucidate the genetic mechanisms controlling species specificity in M. grisea, we performed a genetic analysis of species-specific avirulence on this rice population. Avirulent and virulent progeny segregated in a 1:1 ratio on the 2 rice cultivars 'Lijiangxintuanheigu' (LTH) and 'Shin2', suggesting that a single locus, designated PRE1, was involved in the specificity. In a combination between 'Kusabue' and 'Tsuyuake', the segregation of the 4 possible phenotypes of F1 progeny was significantly different from the expected 3:1:3:1 and instead fit a ratio of 2:0:1:1. This indicated that 2 loci, PRE1 and AVR2, were involved in specific parasitism on rice. These results suggest that the species specificity of M. grisea on rice is governed by species-dependent genetic mechanisms that are similar to the gene-for-gene interactions controlling cultivar specificity. Pathogenicity tests with various plant species revealed that the Digitaria isolate 6023 was exclusively parasitic on crabgrass. Genetic linkage analysis showed that PRE1 was mapped on chromosome 3 with respect to RAPD and SSR markers. RAPD marker S361 was linked to the avirulence gene at a distance of ~6.4 cM. Two SSR markers, m677-678 and m77-78, were linked to the PRE1 gene on M. grisea chromosome 3 at distances of 5.9 and 7.1 cM, respectively. Our results will facilitate positional cloning and functional studies of this gene.