FLIM and FCS detection in laser-scanning microscopes: increased efficiency by GaAsP hybrid detectors

Photon counting detectors currently used in fluorescence lifetime microscopy have a number of deficiencies that result in less-than-ideal signal-to-noise ratio of the lifetimes obtained: either the quantum efficiency is unsatisfactory or the active area is too small, and afterpulsing or tails in the temporal response contribute to overall timing inaccuracy. We have therefore developed a new FLIM detector based on a GaAsP hybrid photomultiplier. Compared with conventional PMTs and SPADs, GaAsP hybrid detectors have a number of advantages: The detection quantum efficiency reaches or surpasses the efficiency of fast SPADs, and the active area is on the order of 5 mm², compared with 2.5 10⁻³ mm² for a SPAD. The TCSPC response is clean, without the bumps and the diffusion tails typical for PMTs and SPADs. Most important, the hybrid detector is intrinsically free of afterpulsing. FLIM results are therefore free of signal-dependent background, and FCS curves are free of the known afterpulsing peak. We demonstrate the performance of the new detector for multiphoton NDD FLIM and for FCS.

Differential Levels of Cytokines and Soluble Fas Ligand between Tuberculous and Malignant Effusions

Tuberculous pleurisy, which is characterized by an extensive inflammatory exudate in the pleural space, is a common manifestation of extrapulmonary tuberculosis caused by Mycobacterium tuberculosis infection but is difficult to diagnose. This study compared concentrations of three cytokines (interferon-γ and interleukin [IL]−2 and −4) and soluble Fas ligand in serum and pleural effusions from 36 patients with tuberculous pleurisy, 30 with malignant pleurisy and 30 healthy volunteers. Interferon-γ concentration was significantly higher in serum and pleural effusions, and the concentration of soluble Fas ligand was significantly higher in pleural effusion, from patients with tuberculous pleurisy than in those with malignant pleurisy. Levels of IL-2 and IL-4 were also raised in serum, but failed to reach statistical significance. Interferon-γ and soluble Fas ligand levels were significantly higher in pleural effusion than in serum. Pleural soluble Fas ligand concentrations correlated linearly with those of interferon-γ in patients with tuberculous pleurisy. These findings suggest a predominant T-helper-1 response to M. tuberculosis infection.

Synthesis of nanobioglass and formation of apatite rods to occlude exposed dentine tubules and eliminate hypersensitivity

The occlusion of patent dentine tubules may reduce or eliminate hypersensitivity by restricting dentinal fluid movement. The efficacy of a novel sol-gel nanobioglass and a melt-derived bioglass to occlude tubules and promote apatite formation was tested by mechanically brushing a slurry of bioglass powder and human saliva onto dentine possessing exposed tubules. Scanning electron microscopy, focused ion beam and energy-dispersive X-ray spectroscopy were used to characterize the powders and assess tubule occlusion. Melt-derived bioglass possessed an irregular particle morphology and had a mean size of 3.30 +/- 0.42 microm. The sol-gel bioglass particles were spherical, with a mean size of 0.65 +/- 0.19 microm. Dentine treated with melt-derived bioglass exhibited a tightly adherent continuous apatite layer. Treatment with nanobioglass resulted in particle deposition within tubules and formation of apatite rods which were tightly adherent to tubule walls and continuous to a measured depth of 270 microm.

Resonant tunneling in the quantum Hall regime: measurement of fractional charge

In experiments on resonant tunneling through a "quantum antidot" (a potential hill) in the quantum Hall (QH) regime, periodic conductance peaks were observed as a function of both magnetic field and back gate voltage. A combination of the two periods constitutes a measurement of the charge of the tunneling particles and implies that charge deficiency on the antidot is quantized in units of the charge of quasi-particles of the surrounding QH condensate. The experimentally determined value of the electron charge e is 1.57 x 10(-19) coulomb = (0.98 +/- 0.03) e for the states v = 1 and v = 2 of the integer QH effect, and the quasi-particle charge is 5.20 x 10(-20) coulomb = (0.325 +/- 0.01)e for the state v = (1/3) of the fractional QH effect.

Oxidative stress signaling in Alzheimer's disease

Multiple lines of evidence demonstrate that oxidative stress is an early event in Alzheimer's disease (AD), occurring prior to cytopathology, and therefore may play a key pathogenic role in AD. Oxidative stress not only temporally precedes the pathological lesions of the disease but also activates cell signaling pathways, which, in turn, contribute to lesion formation and, at the same time, provoke cellular responses such as compensatory upregulation of antioxidant enzymes found in vulnerable neurons in AD. In this review, we provide an overview of the evidence of oxidative stress and compensatory responses that occur in AD, particularly focused on potential sources of oxidative stress and the roles and mechanism of activation of stress-activated protein kinase pathways.

Mathematical Modelling of Immune Response in Tissues

We have developed a spatial–temporal mathematical model (PDE) to capture fundamental aspects of the immune response to antigen. We have considered terms that broadly describe intercellular communication, cell movement, and effector function (activation or inhibition). The PDE model is robust to variation in antigen load and it can account for (1) antigen recognition, (2) an innate immune response, (3) an adaptive immune response, (4) the elimination of antigen and subsequent resolution of the immune response or (5) equilibrium of the immune response to the presence of persistent antigen (chronic infection) and the formation of a granuloma.

Association of haplotypes spanning PDZ-GEF2, LOC728637 and ACSL6 with schizophrenia in Han Chinese

BACKGROUND

Schizophrenia is a complex genetic disorder caused by multiple genetic and environmental factors. Several lines of linkage and association studies have repeatedly suggested that the chromosome 5q22-33 region is implicated in the aetiology of schizophrenia. However, most of the previous studies on the linkage of 5q22-33 with schizophrenia were from European populations, and it was not well characterised in other populations.

METHODS

We analysed eight single nucleotide polymorphisms (SNPs) located in the 5q23.3 region in a cohort of 506 schizophrenia patients and 672 control subjects from south western China. Single marker association, haplotypic association, sex-specific association and molecular evolutionary analysis were performed.

RESULTS

Single marker analysis indicated that SNP5 (rs1355095) in LOC728637 is associated with schizophrenia. When males and females were analysed separately, SNP4 (rs31251) in PDZ-GEF2 is associated with schizophrenia in females. Further analysis using haplotypes demonstrated that a haplotype block spanning PDZ-GEF2, LOC728637 and ACSL6 is highly associated with schizophrenia and several haplotypes in this haploblock have about twofold to 10-fold increase in the affected subjects. In addition, molecular evolutionary analysis suggests that PDZ-GEF2 has undergone adaptive evolution due to Darwinian positive selection in the human lineage.

CONCLUSION

Our data provide evidence of the association of 5q22-33 with schizophrenia in Han Chinese. This chromosomal region is likely responsible for genetic susceptibility to schizophrenia, supporting previous data from European patients. In addition, our evolutionary analysis is consistent with the hypothesis that genes contributing to schizophrenia are likely under positive selection during human evolution.

Zirconia toughened alumina ceramic foams for potential bone graft applications: fabrication, bioactivation, and cellular responses

Zirconia toughened alumina (ZTA) has been regarded as the next generation orthopedic graft material due to its excellent mechanical properties and biocompatibility. Porous ZTA ceramics with good interconnectivity can potentially be used as bone grafts for load-bearing applications. In this work, three-dimensional (3D) interconnected porous ZTA ceramics were fabricated using a direct foaming method with egg white protein as binder and foaming agent. The results showed that the porous ZTA ceramics possessed a bimodal pore size distribution. Their mechanical properties were comparable to those of cancellous bone. Due to the bio-inertness of alumina and zirconia ceramics, surface bioactivation of the ZTA foams was carried out in order to improve their bioactivity. A simple NaOH soaking method was employed to change the surface chemistry of ZTA through hydroxylation. Treated samples were tested by conducting osteoblast-like cell culture in vitro. Improvement on cells response was observed and the strength of porous ZTA has not been deteriorated after the NaOH treatment. The porous 'bioactivated' ZTA ceramics produced here could be potentially used as non-degradable bone grafts for load-bearing applications.

Dentin phosphoprotein frameshift mutations in hereditary dentin disorders and their variation patterns in normal human population

BACKGROUND

Dentin phosphoprotein (DPP) is the most abundant non-collagenous protein in dentin, which is highly phosphorylated and plays key roles in dentin biomineralization. The aetiology of isolated hereditary dentin disorders in most affected families is largely unknown and the association between DPP and dentin disorders has not been well established. This study aims to determine whether there are some involvements for DPP mutations in inherited dentin disorders and to clarify the sequence variation patterns of DPP in normal population.

METHODS

Genomic DNA was analysed in eight families with hereditary dentin disorders and 110 individuals in the normal population. The full coding sequence of DPP was amplified by polymerase chain reaction (PCR) and screened for mutations and variations by direct sequencing and TOPO TA-cloning sequencing.

RESULTS

Five frameshift mutations in DPP coding region were identified in five of the eight families. The mutations co-segregated with the disease phenotypes in affected families and were not found in 220 control chromosomes. In the normal population, we revealed 14 in-frame indels (insertion/deletion), six non-synonymous single nucleotide polymorphisms (SNPs), and five synonymous SNPs in the DPP coding region. These variants display extensive linkage disequilibrium and constitute a total of 15 haplotypes with three predominant haplotypes in the investigated normal population.

CONCLUSIONS

Our data provide the first evidence that DPP mutations can cause hereditary dentin disorders and suggest that in-frame length variations and missense SNPs in DPP have no obvious pathogenetic effects on dentin formation.

Chitosan nanofibers from an easily electrospinnable UHMWPEO-doped chitosan solution system

Conversion of natural biopolymer chitosan into nanofibers through electrospinning has significant usefulness in various biomedical applications, in particular, for constructing a biomimetic and bioactive nanofibrous artificial extracellular matrix for engineering various tissues. Here, we show that introduction of an ultrahigh-molecular-weight poly(ethylene oxide) (UHMWPEO) into aqueous chitosan solutions remarkably enhances the formation of chitosan nanofibrous structure and leads to much lower loading of the water soluble fiber-forming aiding agent of PEO down to 5 wt % as compared to previous high PEO loadings in the electrospun chitosan nanofibers. The excellent electrospinnability of the current formulation renders electrospinning of natural biopolymer chitosan a robust process for large-scale production of practically applicable nanofibrous structures.

Biomimetic and bioactive nanofibrous scaffolds from electrospun composite nanofibers

Electrospinning is an enabling technology that can architecturally (in terms of geometry, morphology or topography) and biochemically fabricate engineered cellular scaffolds that mimic the native extracellular matrix (ECM). This is especially important and forms one of the essential paradigms in the area of tissue engineering. While biomimesis of the physical dimensions of native ECM's major constituents (eg, collagen) is no longer a fabrication-related challenge in tissue engineering research, conveying bioactivity to electrospun nanofibrous structures will determine the efficiency of utilizing electrospun nanofibers for regenerating biologically functional tissues. This can certainly be achieved through developing composite nanofibers. This article gives a brief overview on the current development and application status of employing electrospun composite nanofibers for constructing biomimetic and bioactive tissue scaffolds. Considering that composites consist of at least two material components and phases, this review details three different configurations of nanofibrous composite structures by using hybridizing basic binary material systems as example. These are components blended composite nanofiber, core-shell structured composite nanofiber, and nanofibrous mingled structure.

Causes of oxidative stress in Alzheimer disease

Oxidative stress is one of the earliest events of Alzheimer disease (AD), with implications as an important mediator in the onset, progression and pathogenesis of the disease. The generation of reactive oxygen species (ROS) and its consequent cellular damage/response contributes to much of the hallmark AD pathology seen in susceptible neurons. The sources of ROS-mediated damage appear to be multi-faceted in AD, with interactions between abnormal mitochondria, redox transition metals, and other factors. In this review, we provide an overview of these potential causes of oxidative stress in AD.

Magnetic counter-gravity flow separation of electrically prepolarised lymphoid cells

A novel principle is proposed for a differential separation of live cells (such as leucocytes) from a main flow. A microfluidic device with planar insulated electrodes as the side walls of the channel was manufactured and tested. An array of insulated vertical conductor wires was inserted along the axis of the channel and used to impose Lorentz forces upon polarisable particles that moved with the flow. Polystyrene microspheres and lymphoid cell lines (DOHH2 and K562) were used to test the ability of the setting to impose a force field that induced consistent vertical motion. The direction of electric current was found to directly influence the number of cells or microspheres that were sampled at the surface of the flow. Lorentz force was considered to be active upon cells due to an overall polarisation of the membrane surface. The consequence of the magnetic force was that the polarised cells were moved vertically upwards (opposing gravity). The setting was effective for increasing the number of extracted cells from a main flow or for increasing the concentration of DOHH2 cells in a mixed population with K562 in culture medium. The limitations of the work parameters (potential-current) were found to be dependent upon the cell type.

Antitumor and immunostimulating effects of Anoectochilus formosanus Hayata

The water extract of Anoectochilus formosanus Hayata showed a potent tumor inhibitory activity in BALB/c mice after subcutaneous transplantation of CT-26 murine colon cancer cells. The tumor-inhibition ratios of mice pre-administered with A. formosanus for 2 days before tumor transplantation, and treated further for 12 consecutive days, were 55.4% and 58.9% at the oral dose of 50 and 10 mg/mouse per day, respectively. Even for the tumor-bearing mice, after oral administration of the water extract of A. formosanus for 12 consecutive days, the tumor inhibition ratios were still 23.8% and 40.5% at doses of 50 and 10 mg/mouse, respectively. Because the low-concentration water extract of A. formosanus does not show direct cytotoxicity in CT-26 tumor cells, we observed further that oral administration of the water extract of A. formosanus may activate murine immune responses, such as stimulating the proliferation of lymphoid tissues and activating the phagocytosis of peritoneal macrophages against Staphylococcus aureus. This study suggests that the antitumor activity of A. formosanus may be associated with its potent immunostimulating effect. It is worth further analyzing the immunomodulating component purified from A. formosanus, and evaluating its potential value for the treatment of human cancers.

Defining the orientation of the tandem fusions that occurred during the evolution of Indian muntjac chromosomes by BAC mapping

The Indian muntjac (Muntiacus muntjak vaginalis) has a karyotype of 2n=6 in the female and 7 in the male, the karyotypic evolution of which through extensive tandem fusions and several centric fusions has been well-documented by recent molecular cytogenetic studies. In an attempt to define the fusion orientations of conserved chromosomal segments and the molecular mechanisms underlying the tandem fusions, we have constructed a highly redundant (more than six times of whole genome coverage) bacterial artificial chromosome (BAC) library of Indian muntjac. The BAC library contains 124,800 clones with no chromosome bias and has an average insert DNA size of 120 kb. A total of 223 clones have been mapped by fluorescent in situ hybridization onto the chromosomes of both Indian muntjac and Chinese muntjac and a high-resolution comparative map has been established. Our mapping results demonstrate that all tandem fusions that occurred during the evolution of Indian muntjac karyotype from the acrocentric 2n=70 hypothetical ancestral karyotype are centromere-telomere (head-tail) fusions.

Genetic evidence of a strong functional constraint of neurotrypsin during primate evolution

Neurotrypsin is one of the extra-cellular serine proteases that are predominantly expressed in the brain and involved in neuronal development and function. Mutations in humans are associated with autosomal recessive non-syndromic mental retardation (MR). We studied the molecular evolution of neurotrypsin by sequencing the coding region of neurotrypsin in 11 representative non-human primate species covering great apes, lesser apes, Old World monkeys and New World monkeys. Our results demonstrated a strong functional constraint of neurotrypsin that was caused by strong purifying selection during primate evolution, an implication of an essential functional role of neurotrypsin in primate cognition. Further analysis indicated that the purifying selection was in fact acting on the SRCR domains of neurotrypsin, which mediate the binding activity of neurotrypsin to cell surface or extra-cellular proteins. In addition, by comparing primates with three other mammalian orders, we demonstrated that the absence of the first copy of the SRCR domain (exon 2 and 3) in mouse and rat was due to the deletion of this segment in the murine lineage.

A rapid assessment of community-wide HIV/STI intervention in China

BACKGROUND/OBJECTIVES

The key to HIV/STI control is community-wide intervention (CWI) which depends heavily on continuous monitoring and evaluation. Unfortunately, comprehensive CWI assessment methodology and reports are generally lacking. This study developed, applied, and evaluated a rapid tool for assessing CWI in China.

METHODS

A total of 120 county level respondents in charge of county-wide responses to HIV/STI throughout China were selected randomly and surveyed using a structured inventory consisting of three tiers of indicators developed via consensus group techniques. The respondents were asked to rate each of the indicators against a five grade (1-5) scale. 30 pairs of the same staff from within Anhui Province were surveyed to gauge inter-rater reliability.

RESULTS

Response rate for the nationwide survey was 85% and for inter-rater reliability survey, 90%. Correlation coefficients between the inter-rater ratings ranged from 0.68 to 0.95. The overall average rating of CWI in China was 2.85. Average ratings for the six first tier indicators, organisation and policy development, goals and objectives setting, project and action planning, resource exploitation, project and task implementation, and CWI evaluation were 2.87, 2.83, 2.67, 2.77, 3.26, and 2.71 respectively. Ratings derived for the 24 second tier indicators ranged from 2.1 to 3.86; while for the 96 third tier indicators, 1.90 to 4.40

CONCLUSIONS

The instrument developed proved to be reliable, useful, and easily applicable in common communities. Application of it in China revealed that a large gap exists between desired and actual CWI, and areas meriting particular attention include policy and incentives development, intervention planning and evaluation, and fund raising and utilisation.

Effects of Anoectochilus formosanus Hayata extract and glucocorticoid on lung maturation in preterm rats

We investigated the effects of maternal administration of Anoectochilus formosanus extract and dexamethasone on lung maturation in preterm rats. A. formosanus group mothers were tube-fed A. formosanus extract (300 mg/kg body wt./day) for 7 days from days 12-18 of gestation. Dexamethasone group mothers were injected intraperitoneally with dexamethasone (0.2 mg/kg body wt.) in saline on day 18 of gestation. Control group mothers were similarly injected with saline alone. On day 19 of gestation, fetuses were delivered by cesarean section. A. formosanus treatment significantly increased the fetal lung/body weight ratio, as compared to dexamethasone treatment. Saturated phosphatidylcholine levels in fetal lung tissue and growth hormone levels in maternal serum were significantly increased in the A. formosanus- and dexamethasone-treated groups as compared to controls. The histological appearance of preterm rat lungs revealed extensive branching of intermediate airways, denser mesenchyme, and more epithelial tubules in the dexamethasone and A. formosanus groups as compared with the control group. These results suggest that antenatal A. formosanus treatment may play a role in accelerating fetal rat lung maturation.

1-3 connectivity piezoelectric ceramic-polymer composite transducers made with viscous polymer processing for high frequency ultrasound

Potential applications of high frequency ultrasound exist because of the high spatial resolution consequent upon short wavelength. The frequencies of interest, typically from 25 MHz upwards, are easily supported by modern instrumentation but the capabilities of ultrasonic transducers have not kept pace and the transducers in high frequency commercial ultrasonic systems are still made with single-phase crystal, ceramic or piezopolymer materials. Despite potential performance advantages, the 1-3 connectivity piezoelectric ceramic-polymer composite materials now widely used at lower ultrasonic frequencies have not been adopted because of manufacturing difficulties. These difficulties are centred on fabrication of the 1-3 piezoceramic bristle-block comprising tall, thin pillars upstanding from a supporting stock. Fabrication techniques which have been explored already include injection moulding, mechanical dicing, and laser machining. Here, we describe an alternative technique based on viscous polymer processing (VPP) to produce net shape ceramic bristle-blocks. VPP produces green-state ceramic with rheological properties suitable for embossing. We outline how this can be created then report on our work to fabricate PZT bristle-blocks with lateral pillar dimensions of the order of 50 microm and height-to-width ratios of the order of 10. These have been backfilled with low pre-cure viscosity polymer and made into complete 1-3 piezocomposite transducer elements. We outline the performance of the transducers in terms of electrical impedance and pulse-echo behaviour and show that it corresponds well with computer modelling. We conclude that VPP is a promising technique to allow the established advantages of piezocomposite material to be exploited at higher frequencies than have been possible so far.

Modulation of in vivo 3-deoxyglucosone levels

Fructoselysine 3-phosphate is synthesized in vivo by the recently discovered fructoseamine-3-kinase (F3K) from fructoselysine and ATP and decomposes to lysine, Pi and 3-deoxyglucosone (3DG). This pathway appears to dominate 3DG production in vivo, making it possible to modulate 3DG levels by stimulating or inhibiting the reaction. Present inhibitors are non-reacting substrate analogues with relatively high Ki values and can inhibit F3K sufficiently in vivo to reduce 3DG in diabetic rat plasma by approx. 50%. Stimulation of the F3K pathway by feeding glycated casein causes an increase of 10–20-fold in plasma levels of 3DG and 3-fold in kidney tubules. Consequences of this increase were studied in two systems: the Eker rat, a model of susceptible kidney tubules; and birth rates in two rat strains. In both cases substantial pathological effects were observed. In the Eker rats, an approx. 3-fold increase in kidney lesions was observed (P<0.00001). In both Fischer 344 and Sprague–Dawley rats, birth rates were reduced by 56% (P<0.0001) and 12% (P<0.015) respectively. These results suggest that inhibition of F3K is a promising new therapeutic target for diabetic complications, as well as other 3DG-dependent pathologies.