A mathematical model on the propagation of tau pathology in neurodegenerative diseases.

A system of partial differential equations is developed to study the spreading of tau pathology in the brain for Alzheimer's and other neurodegenerative diseases. Two cases are considered with one assuming intracellular diffusion through synaptic activities or the nanotubes that connect the adjacent cells. The other, in addition to intracellular spreading, takes into account of the secretion of the tau species which are able to diffuse, move with the interstitial fluid flow and subsequently taken up by the surrounding cells providing an alternative pathway for disease spreading. Cross membrane transport of the tau species are considered enabling us to examine the role of extracellular clearance of tau protein on the disease status. Bifurcation analysis is carried out for the steady states of the spatially homogeneous system yielding the results that fast cross-membrane transport combined with effective extracellular clearance is key to maintain the brain's healthy status. Numerical simulations of the first case exhibit solutions of travelling wave form describing the gradual outward spreading of the pathology; whereas the second case shows faster spreading with the buildup of neurofibrillary tangles quickly elevated throughout. Our investigation thus indicates that the gradual progression of the intracellular spreading case is more consistent with the clinical observations of the development of Alzheimer's disease.

Tris(methylthio)methane produced by Mortierella hyalina affects sulfur homeostasis in Arabidopsis.

Microbial volatiles are important factors in symbiotic interactions with plants. Mortierella hyalina is a beneficial root-colonizing fungus with a garlic-like smell, and promotes growth of Arabidopsis seedlings. GC-MS analysis of the M. hyalina headspace and NMR analysis of the extracted essential oil identified the sulfur-containing volatile tris(methylthio)methane (TMTM) as the major compound. Incorporation of the sulfur from the fungal volatile into plant metabolism was shown by 34S labeling experiments. Under sulfur deficiency, TMTM down-regulated sulfur deficiency-responsive genes, prevented glucosinolate (GSL) and glutathione (GSH) diminishment, and sustained plant growth. However, excess TMTM led to accumulation of GSH and GSL and reduced plant growth. Since TMTM is not directly incorporated into cysteine, we propose that the volatile from M. hyalina influences the plant sulfur metabolism by interfering with the GSH metabolism, and alleviates sulfur imbalances under sulfur stress.

A mathematical model demonstrating the role of interstitial fluid flow on the clearance and accumulation of amyloid ß in the brain.

A system of partial differential equations is developed to describe the formation and clearance of amyloid ß (Aß) and the subsequent buildup of Aß plaques in the brain, which are associated with Alzheimer's disease. The Aß related proteins are divided into five distinct categories depending on their size. In addition to enzymatic degradation, the clearance via diffusion and the outflow of interstitial fluid (ISF) into the surrounding cerebral spinal fluid (CSF) are considered. Treating the brain tissue as a porous medium, a simplified two-dimensional circular geometry is assumed for the transverse section of the brain leading to a nonlinear, coupled system of PDEs. Asymptotic analysis is carried out for the steady states of the spatially homogeneous system in the vanishingly small limit of Aß clearance rate. The PDE model is studied numerically for two cases, a spherically symmetric case and a more realistic 2D asymmetric case, allowing for non-uniform boundary conditions. Our investigations demonstrate that ISF advection is a key component in reproducing the clinically observed accumulation of plaques on the outer boundaries. Furthermore, ISF circulation serves to enhance Aß clearance over diffusion alone and that non-uniformities in ISF drainage into the CSF can lead to local clustering of plaques. Analysis of the model also demonstrates that plaque formation does not directly correspond to the high presence of toxic oligomers.

Different spontaneous breathing trials in patients with atrial fibrillation.

INTRODUCTION: Weaning from mechanical ventilation is one of the most important and challenging problems for most intensive care unit (ICU) patients. Spontaneous breathing trial (SBT) is the most common method used to evaluate patients' ability to breathe by themselves and plays an important role in decision making for weaning. The aim of our study was to investigate the effect of different methods of SBT in respiratory care unit (RCU) patients with atrial fibrillation (AF) on weaning outcome. METHODS: We retrospectively analyzed different methods of SBT in patients with and without AF. We enrolled RCU patients who required mechanical ventilation and had undergone transthoracic echocardiography from January 2011 to January 2012. RESULTS: There was a higher SBT passing rate among AF patients who received pressure support ventilation (PSV) trial than in those who received T-piece trail (92.5% vs. 73.1%, p=0.041). The weaning rates between these two groups were not significantly different (83.8% vs. 94.7%, p=0.403). Total ventilator days were longer in T-piece group than in PSV group (median 40.0, IQR: 18.2-125.1 days vs. 33.0, IQR: 29.6-51.0 days respectively, p=0.580), but this difference was not statistically significant. These results were not found in patients without AF. CONCLUSIONS: The use of PSV trial might be considered first instead of T-piece trial for SBT when AF patients were ready to wean.

Of mice and men: novel insights regarding constitutive and recruitable brown adipocytes.

Recently, there has been great attention given to the possibility of combating obesity by targeting brown fat activity or increasing differentiation of brown adipocytes in white fat depots through a process termed 'browning'. Sympathetic innervation of brown and white adipose tissues provides adrenergic input that drives thermogenesis and regulates fatty acid metabolism, as well as stimulating adipogenesis of recruitable brown adipocyte tissue (rBAT, also known as beige or brite) in white fat. Other factors acting in an endocrine or autocrine/paracrine manner in adipose tissue may also stimulate browning. There have been significant recent advances in understanding the mechanisms of increasing adipose tissue energy expenditure, as well as how brown adipocytes appear in white fat depots, including via de novo adipogenesis from tissue precursor cells. In this article, we integrate this new knowledge with a historical perspective on the discovery of 'browning'. We also provide an overview of constitutive BAT vs rBAT in mouse and human.

Thyroid hormone receptor represses miR-17 expression to enhance tumor metastasis in human hepatoma cells.

MicroRNAs (miRNAs) are thought to control tumor metastasis through direct interactions with target genes. Thyroid hormone (T3) and its receptor (TR) are involved in cell growth and cancer progression. However, the issue of whether miRNAs participate in T3/TR-mediated tumor migration is yet to be established. In the current study, we demonstrated that T3/TR negatively regulates mature miR-17 transcript expression, both in vitro and in vivo. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays localized the regions responding to TR-mediated repression to positions -2234/-2000 of the miR-17 promoter sequence. Overexpression of miR-17 markedly inhibited cell migration and invasion in vitro and in vivo, mediated via suppression of matrix metalloproteinases (MMP)-3. Moreover, p-AKT expression was increased in miR-17-knockdown cells that led to enhanced cell invasion, which was blocked by LY294002. Notably, low miR-17 expression was evident in highly metastatic cells. The cell migration ability was increased by T3, but partially reduced upon miR-17 overexpression. Notably, TRα1 was frequently upregulated in hepatocellular carcinoma (HCC) samples and associated with low overall survival (P=0.023). miR-17 expression was significantly negatively associated with TRα1 (P=0.033) and MMP3 (P=0.043) in HCC specimens. Data from our study suggest that T3/TR, miR-17, p-AKT and MMP3 activities are interlinked in the regulation of cancer cell metastasis.

Thyroid hormone suppresses cell proliferation through endoglin-mediated promotion of p21 stability.

Hypothyroidism has been associated with significantly elevated risk for hepatocellular carcinoma (HCC), although the precise underlying mechanisms remain unknown at present. Thyroid hormone (T3) and its receptor (TR) are involved in metabolism and growth. Endoglin is a T3/TR candidate target gene identified from our previous studies. Here, we demonstrated that T3 positively regulates endoglin mRNA and protein levels, both in vitro and in vivo. The thyroid hormone response elements of endoglin were identified at positions -2114/-2004 and -2032/-1973 of the promoter region using the electrophoretic mobility shift assay and chromatin immunoprecipitation assay. Endoglin was downregulated in the subgroups of HCC patients and significantly associated with histology grade (negative association, P=0.001), and this expression level was significantly associated with TRα1 in these HCC patients. Our results clearly indicate that p21 is involved in T3-mediated suppression of cell proliferation. Knock down of endoglin expression in HCC cells facilitated p21 polyubiquitination and promoted cell proliferation in the presence of T3. The data collectively suggest that T3/TR signaling suppresses cell proliferation by upregulating endoglin, in turn, affecting p21 stability. The results indicate that endoglin has a suppressor role to inhibit cell proliferation in HCC cell lines.

Thyroid hormone receptors promote metastasis of human hepatoma cells via regulation of TRAIL.

Although accumulating evidence has confirmed the important roles of thyroid hormone (T(3)) and its receptors (TRs) in tumor progression, the specific functions of TRs in carcinogenesis remain unclear. In the present study, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) was directly upregulated by T(3) in TR-overexpressing hepatoma cell lines. TRAIL is an apoptotic inducer, but it can nonetheless trigger non-apoptotic signals favoring tumorigenesis in apoptosis-resistant cancer cells. We found that TR-overexpressing hepatoma cells treated with T(3) were apoptosis resistant, even when TRAIL was upregulated. This apoptotic resistance may be attributable to simultaneous upregulation of Bcl-xL by T(3), because (1) knockdown of T(3)-induced Bcl-xL expression suppressed T(3)-mediated protection against apoptosis, and (2) overexpression of Bcl-xL further protected hepatoma cells from TRAIL-induced apoptotic death, consequently leading to TRAIL-promoted metastasis of hepatoma cells. Moreover, T(3)-enhanced metastasis in vivo was repressed by the treatment of TRAIL-blocking antibody. Notably, TRAIL was highly expressed in a subset of hepatocellular carcinoma (HCC) patients, and this high-level expression was significantly correlated with that of TRs in these HCC tissues. Together, our findings provide evidence for the existence of a novel mechanistic link between increased TR and TRAIL levels in HCC. Thus, TRs induce TRAIL expression, and TRAIL thus synthesized acts in concert with simultaneously synthesized Bcl-xL to promote metastasis, but not apoptosis.

A chromatographically purified human TGF-ß1 fraction from virally inactivated platelet lysates.

BACKGROUND AND OBJECTIVES: TGF-ß1 exerts important physiological functions in osteogenesis and chondrogenesis and may be of therapeutic interest. The aim of this work was to develop a scalable purification process of TGF-ß1 from virally inactivated human platelets. STUDY DESIGN AND METHODS: Apheresis platelet concentrates (N=12) were solvent/detergent (S/D) treated (1% TnBP/1% Triton X-45; 31°C) and the resulting platelet lysates were clarified by oil extraction and centrifugation, then chromatographed on an anion-exchange DEAE-Sepharose Fast-Flow column equilibrated in a PBS buffer, pH 7.5. The column was washed to eliminate unbound proteins and the S/D agents. Bound proteins were eluted using a 1 M NaCl-PBS buffer pH 7.5 (DEAE-eluate). The content in TGF-ß1, PDGF-AB, VEGF, IGF-1, EGF, and b-FGF was measured by ELISA. Proteins, lipids, and S/D agents were assessed. Protein profile was determined by SDS-PAGE under reduced or non-reduced conditions. RESULTS: Most proteins, including albumin and immunoglobulins G, A, and M did not bind to the DEAE column as evidenced also by SDS-PAGE. Essentially all PDGF, VEGF, and IGF were in the breakthrough. The DEAE-eluate contained close to 60% of the TGF-ß1 at a mean concentration of about 102 ng/ml, whereas EGF, b-FGF were at about 0.72 and 0.18 ng/ml, respectively. The content in TnBP and Triton X-45 was <2 ppm. CONCLUSION: A fraction enriched in TGF-ß1 can be prepared from virally inactivated human platelet lysates using an easily scale process. Its interest in regenerative medicine and cell therapy will be evaluated in further studies.

A virally inactivated functional growth factor preparation from human platelet concentrates.

BACKGROUND: Human platelet growth factors (HPGF) are essential for tissue regeneration and may replace fetal bovine serum (FBS) in cell therapy. No method for the manufacture of standardized virally inactivated HPGF has been developed yet. STUDY DESIGN AND METHODS: Platelet concentrates (PC) were subjected to solvent/detergent (S/D) treatment (1% TnBP/1% Triton X-45), oil extraction, hydrophobic interaction chromatography and sterile filtration. Platelet-derived growth factor (PDGF)-AB, -BB and -AA, transforming growth factor-beta1 (TGF-beta1), epidermal growth factor (EGF), insulin-like growth factor-1 (IGF-1) and vascular endothelium growth factor (VEGF) were measured by ELISA. Composition in proteins and lipids was determined, protein profiles were obtained by SDS-PAGE, and TnBP and Triton X-45 were assessed by gas chromatography and high-performance liquid chromatography, respectively. Cell growth promoting activity of HPGF was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay using human embryonic kidney (HEK293A) fibroblast and Statens Seruminstitute rabbit corneal (SIRC) epithelial cell lines. RESULTS: The GF preparation contained a mean of 16.66, 2.04, 1.53, 72.19, 0.33, 48.59 and 0.44 ng/ml of PDGF-AB, -BB, -AA, TGF-beta1, EGF, IGF-1 and VEGF, respectively. The protein profile was typical of platelet releasates and had less than 2 p.p.m. of residual S/D agents. MTS assay of HEK293A and SIRC cultures showed that the GF preparation at 10% and 0.1% (v/v), respectively, could successfully replace 10% FBS for cell proliferation. Cell-stimulating activity of HPGF on HEK293A was over twice that of PC releasates. CONCLUSION: STANDARDIZED and functional virally inactivated HPGF can be prepared from human PC for possible applications in cell therapy and regenerative medicine.

Areca nut extract represses migration and differentiation while activating matrix metalloproteinase-9 of normal gingival epithelial cells.

BACKGROUND AND OBJECTIVE: Areca (betel) chewing is associated with an increase in the incidence of periodontal diseases. Aberrations in matrix metalloproteinase (MMP) expression have been reported to be associated with periodontal disease. This study investigated the effects of areca nut extract on MMP activity and the phenotype of human gingival epithelial cells. MATERIAL AND METHODS: Reverse transcription-polymerase chain reaction, western blotting and gelatin zymography were used to assay MMPs. Cell viability, mobility and detachment assays were performed to characterize the phenotypic impact. Confocal microscopy was employed to evaluate cell aggregation and the distribution of E-cadherin and F-actin. RESULTS: Treatment of gingival epithelial cells with 10 microg/mL of areca nut extract reduced its cell viability. Treatment with 5 and 10 microg/mL of areca nut extract for 24 h activated MMP-9 but not MMP-2 in gingival epithelial cells. This activation could be nuclear factor-kappaB dependent and was abrogated by 10 microM curcumin. Areca nut extract also reduced the migration and detachment of gingival epithelial cells. The differentiated cell-cell contact of gingival epithelial cells was markedly impaired by areca nut extract. This was accompanied by a disruption of distribution of E-cadherin and F-actin. CONCLUSION: The areca nut extract-mediated activation of MMP-9 in gingival epithelial cells could signify a potential periodontal pathogenesis in areca chewers. The areca nut extract-mediated inhibition of cell viability and migration, together with the changed aggregation in gingival epithelial cells, suggests that impairment of the re-epithelization underlies the process and this, in turn, might exacerbate gingival inflammation.

Clinical effectiveness and safety experience with alefacept in the treatment of patients with moderate-to-severe chronic plaque psoriasis in Taiwan: results of an open-label, single-arm, multicentre pilot study.

BACKGROUND: The effectiveness and safety of alefacept for the treatment of moderate-to-severe chronic plaque psoriasis has been established in several clinical trials conducted in the United States and Europe. No clinical trial of alefacept has been conducted in Asia. OBJECTIVE: To determine the effectiveness and safety of alefacept in the treatment of psoriasis in Chinese population. DESIGN AND METHODS: This was an open-label, single-arm, multicentre pilot study conducted at three centres. Patients with a body surface area > or = 10% and psoriasis area and severity Index (PASI) > or = 12 were given 15 mg alefacept intramuscularly once a week for 12 weeks and were then followed up for a further 12 weeks. RESULTS: A total of 46 patients was enrolled. Only one subject (2%) achieved a > or = 75% improvement in PASI at week 14. The median improvement in PASI at week 14 after the 12-week treatment was 39%. At any time during the 6-month course, 3 subjects (7%) achieved a Physician Global Assessment (PGA) of 'almost clear', and a > or = 50% and > or = 75% improvement in PASI was seen in 46% and 9%, respectively. There is a trend for decreased counts of CD4(+) and CD8(+) cells after alefacept treatment, but subjects who achieved PASI50 showed a lesser degree of decrease in CD4(+) and CD8(+) counts compared with those in patients who did not achieve PASI50. CONCLUSIONS: This small pilot study indicated that intramuscular alefacept was effective and safe in psoriasis in Chinese patients over 12 weeks of treatment. Further studies are needed to clarify the reason for low PASI 75 effectiveness and the paradoxical lesser decline of CD4(+) and CD8(+) T cells in those who responded.

Preparation of microencapsulated phase-change materials (MCPCMs) by means of interfacial polycondensation.

Microcapsules for energy storage and/or heat transfer applications containing phase-change materials (PCMs-including n-pentadecane, n-eicosane and a paraffin wax) were successfully produced by emulsifying the PCMs as small droplets in an aqueous, water-soluble urea-formaldehyde pre-polymer solution substantially free of emulsifier while polymerizing the pre-polymer at the interface by acid-catalyst. The core/shell structured microcapsules were also characterized with size distribution analysis, scanning electron microscopy, FTIR spectrometry and differential scanning calorimetry.

Effects of insulin-sensitising agents in mice with hepatic insulin resistance.

AIMS/HYPOTHESIS: The metabolic abnormalities of insulin resistance are ameliorated by insulin sensitisers via different mechanisms. Metformin decreases hepatic glucose output, whereas rosiglitazone (RSG) is an agonist for peroxisome proliferator activated receptor (PPAR)gamma, highly expressed in fat. To gain insight into the mechanisms of action of these drugs, we compared their actions in two models of insulin resistance: the obese, hyperglycaemic ob/ob mouse and the liver specific insulin receptor knockout (LIRKO) mouse. METHODS: Control, ob/ob, and LIRKO mice were divided into three groups that received metformin (300 mg/kg body weight/day), RSG (3 mg/kg body weight/day), or placebo for 3 weeks. RESULTS: In the presence of the severe hepatic insulin resistance of the LIRKO mouse, neither metformin nor RSG had any significant effect on glucose or insulin tolerance tests. On the other hand, RSG decreased serum concentrations of total cholesterol, LDL, and HDL in LIRKO mice. Adipocyte PPARgamma gene and protein expression, and adipocyte size were all increased in LIRKO mice treated with RSG, whereas fat-cell size in control animals was decreased by RSG. CONCLUSION/INTERPRETATION: TZDs probably improve some lipid parameters of the dysmetabolic syndrome associated with diabetes mellitus even in the presence of absolute hepatic insulin resistance, but both metformin and TZDs require an operating insulin signalling system in the liver for their effects in glucose homeostasis.

Isolation of a Xanthomonas campestris strain with elevated beta-galactosidase activity for direct use of lactose in xanthan gum production.

AIMS: To isolate a Xanthomonas campestris strain that can use lactose directly for xanthan gum production. METHODS AND RESULTS: The presence of indigenous beta-galactosidase gene in the wild-type Xc17 was detected by PCR and Southern hybridization. Treatment of Xc17 with nitrous acid resulted in the isolation of Xc17L with a 3.5-fold elevation of beta-galactosidase activity capable of growing in lactose-based medium. Xc17L is stable for at least 100 generations in terms of beta-galactosidase expression. The amounts of xanthan produced by Xc17L in lactose-based medium are comparable to those in glucose-based medium. CONCLUSIONS: Xc17L is potentially useful for xanthan production from whey, a waste containing lactose. SIGNIFICANCE AND IMPACT OF THE STUDY: A lactose-utilizing strain of X. campestris strain can be constructed without incorporation of any exotic DNA or antibiotic resistance gene and therefore concern of a gene-modified organism and fear of a spread of an antibiotic-resistant gene are avoided.

Phylogenetic and structural analyses of the oxa1 family of protein translocases.

Mitochondrial Oxa1p homologs have been shown to function in protein export and membrane insertion in bacteria, mitochondria and chloroplasts, but their mode of action, organismal distribution and evolutionary origins are poorly understood. All sequenced homologs of Oxa1p were retrieved from the databases and multiply aligned. All organisms with a fully sequenced genome possess at least one Oxa1p homolog showing that the family is truly ubiquitous. Most prokaryotes possess just one Oxa1p homolog, but several Gram-positive bacteria and one archaeon possess two, and eukaryotes may have as many as six. Although these proteins vary in length over a 5-fold range, they exhibit a common hydrophobic core region of about 200 residues. Multiple sequence alignments reveal conserved residues and provide the basis for structural and phylogenetic analyses that serve to characterize the Oxa1 family.

Plasmids carrying cloned fragments of RF DNA from the filamentous phage (phi)Lf can be integrated into the host chromosome via site-specific integration and homologous recombination.

Different regions of RF DNA from the filamentous bacteriophage phiLf were cloned in Escherichia coli vectors that can not be maintained in Xanthomonas. After introduction into X. campestris pv. campestris 17 (Xc17), most of these constructs were found to integrate into the host chromosome, either by recA-dependent homologous recombination or recA-independent site-specific integration. Mutations in himA, which codes for the alpha-subunit of the Integration Host Factor, does not affect the integration. Integration occurs into a chromosomal region which harbors a copy of a defective phage (4445 bp) that shares a high degree of identity with the phiLf genome. While various parts of the 4445-bp region are susceptible to homologous recombination, site-specific integration requires the attB sequence on the chromosome and the phage attP. The attB shows a high level of sequence identity (22 out of 28 bp) to the dif site required for E. coli Xer site-specific recombination, including the 6-bp central region, and 8/11 identity in both the left XerC-binding arm and the right XerD-binding arm, with the innermost 5 nt of the arms forming a dyad symmetry that is also present in dif. The attP has the same central region and shows 10/11 identity to the dif site in the left arm, but the sequence of the right arm is less conserved than that of attB. The smallest regions still capable of mediating integration are a cloned 72-bp phiLf attP-containing sequence and a 51-bp Xc17 attB-containing sequence, which was reinserted into the Xc17 chromosome after the 4445-bp region had been deleted, indicating that accessory sequences are not necessary and that the integrase required for site-specific integration is neither specified by the 4445-bp Xc17 chromosomal region nor encoded by the phiLf genome.