Effectiveness of submicronized chitosan-coated liposomes in oral absorption of indomethacin

The plasma profile of indomethacin (IMC) after oral administration of IMC-loaded submicronized chitosan-coated liposomes (ssCS-Lip) was evaluated to reveal the effectiveness of the mucoadhesive function for improving the absorption of this poorly absorbable drug. The stomach and small intestine were removed from rats after 1, 2, and 4 hours of oral administration of submicron-sized liposomes (ssLip) or ssCS-Lip containing fluorescent dye, and the retentive properties were confirmed by measuring the amount of dye in each part of the gastrointestinal (GI) tract. Results showed that ssCS-Lip tended to be better retained in the upper part of the GI tract, compared with ssLip, at 1, 2, and 4 hours after administration, and was significantly better retained in the small intestine at 4 hours. The plasma profile and bioavailability of IMC after oral administration of both types of liposomes were improved, compared with oral administration of IMC solution. The maximum residence time of ssCS-Lip was significantly longer than those of ssLip. The extended plasma profile of ssCS-Lip was attributed to its prolonged retention in the upper region of the GI tract, and its delayed migration to the lower part of the intestine, the neutral pH of which is more soluble for IMC, an acidic drug. Therefore, the chitosan-coated ssLip, with its higher retention in the GI tract, is a promising drug carrier for the oral administration of poorly absorbed compounds.     

A three-dimensional FRET analysis to construct an atomic model of the actin-tropomyosin-troponin core domain complex on a muscle thin filament

It is essential to know the detailed structure of the thin filament to understand the regulation mechanism of striated muscle contraction. Fluorescence resonance energy transfer (FRET) was used to construct an atomic model of the actin-tropomyosin (Tm)-troponin (Tn) core domain complex. We generated single-cysteine mutants in the 167-195 region of Tm and in TnC, TnI, and the β-TnT 25-kDa fragment, and each was attached with an energy donor probe. An energy acceptor probe was located at actin Gln41, actin Cys374, or the actin nucleotide-binding site. From these donor-acceptor pairs, FRET efficiencies were determined with and without Ca(2+). Using the atomic coordinates for F-actin, Tm, and the Tn core domain, we searched all possible arrangements for Tm or the Tn core domain on F-actin to calculate the FRET efficiency for each donor-acceptor pair in each arrangement. By minimizing the squared sum of deviations for the calculated FRET efficiencies from the observed FRET efficiencies, we determined the location of Tm segment 167-195 and the Tn core domain on F-actin with and without Ca(2+). The bulk of the Tn core domain is located near actin subdomains 3 and 4. The central helix of TnC is nearly perpendicular to the F-actin axis, directing the N-terminal domain of TnC toward the actin outer domain. The C-terminal region in the I-T arm forms a four-helix-bundle structure with the Tm 175-185 region. After Ca(2+) release, the Tn core domain moves toward the actin outer domain and closer to the center of the F-actin axis.     

Effect of menstrual cycle phase on the ventilatory response to rising body temperature during exercise

To examine the effect of menstrual cycle on the ventilatory sensitivity to rising body temperature, ten healthy women exercised for ~60 min on a cycle ergometer at 50% of peak oxygen uptake during the follicular and luteal phases of their cycle. Esophageal temperature, mean skin temperature, mean body temperature, minute ventilation, and tidal volume were all significantly higher at baseline and during exercise in the luteal phase than the follicular phase. On the other hand, end-tidal partial pressure of carbon dioxide was significantly lower during exercise in the luteal phase than the follicular phase. Plotting ventilatory parameters against esophageal temperature revealed there to be no significant menstrual cycle-related differences in the slopes or intercepts of the regression lines, although minute ventilation and tidal volume did significantly differ during exercise with mild hyperthermia. To evaluate the cutaneous vasodilatory response, relative laser-Doppler flowmetry values were plotted against mean body temperature, which revealed that the mean body temperature threshold for cutaneous vasodilation was significantly higher in the luteal phase than the follicular phase, but there were no significant differences in the sensitivity or peak values. These results suggest that the menstrual cycle phase influences the cutaneous vasodilatory response during exercise and the ventilatory response at rest and during exercise with mild hyperthermia, but it does not influence ventilatory responses during exercise with moderate hyperthermia.     

Thioredoxin reductase 1 deficiency enhances selenite toxicity in cancer cells via a thioredoxin-independent mechanism

Selenium is an essential trace element in mammals, but is toxic at high levels. It is best known for its cancer prevention activity, but cancer cells are more sensitive to selenite toxicity than normal cells. Since selenite treatment leads to oxidative stress, and the Trx (thioredoxin) system is a major antioxidative system, we examined the interplay between TR1 (Trx reductase 1) and Trx1 deficiencies and selenite toxicity in DT cells, a malignant mouse cell line, and the corresponding parental NIH 3T3 cells. TR1-deficient cells were far more sensitive to selenite toxicity than Trx1-deficient or control cells. In contrast, this effect was not seen in cells treated with hydrogen peroxide, suggesting that the increased sensitivity of TR1 deficiency to selenite was not due to oxidative stress caused by this compound. Further analyses revealed that only TR1-deficient cells manifested strongly enhanced production and secretion of glutathione, which was associated with increased sensitivity of the cells to selenite. The results suggest a new role for TR1?in cancer that is independent of Trx reduction and compensated for by the glutathione system. The results also suggest that the enhanced selenite toxicity of cancer cells and simultaneous inhibition of TR1 can provide a new avenue for cancer therapy.     

Presence and functionality of mating type genes in the supposedly asexual filamentous fungus Aspergillus oryzae

The potential for sexual reproduction in Aspergillus oryzae was assessed by investigating the presence and functionality of MAT genes. Previous genome studies had identified a MAT1-1 gene in the reference strain RIB40. We now report the existence of a complementary MAT1-2 gene and the sequencing of an idiomorphic region from A. oryzae strain AO6. This allowed the development of a PCR diagnostic assay, which detected isolates of the MAT1-1 and MAT1-2 genotypes among 180 strains assayed, including industrial tane-koji isolates. Strains used for sake and miso production showed a near-1:1 ratio of the MAT1-1 and MAT1-2 mating types, whereas strains used for soy sauce production showed a significant bias toward the MAT1-2 mating type. MAT1-1 and MAT1-2 isogenic strains were then created by genetic manipulation of the resident idiomorph, and gene expression was compared by DNA microarray and quantitative real-time PCR (qRT-PCR) methodologies under conditions in which MAT genes were expressed. Thirty-three genes were found to be upregulated more than 10-fold in either the MAT1-1 host strain or the MAT1-2 gene replacement strain relative to each other, showing that both the MAT1-1 and MAT1-2 genes functionally regulate gene expression in A. oryzae in a mating type-dependent manner, the first such report for a supposedly asexual fungus. MAT1-1 expression specifically upregulated an α-pheromone precursor gene, but the functions of most of the genes affected were unknown. The results are consistent with a heterothallic breeding system in A. oryzae, and prospects for the discovery of a sexual cycle are discussed.     

Effect of persistent activation of phosphoinositide 3-kinase on heart

AimsInsulin/insulin-like growth factor-1 (IGF-1) signaling plays an important role in many biological processes. The class IA isoform of phosphoinositide 3-kinase (PI3K) is an important downstream effector of the insulin/IGF-1 signaling pathway. The aim of this study is to examine the effect of persistent activation of PI3K on gene expression and markers of cellular senescence in murine hearts.Main methodsTransgenic mice expressing a constitutively active PI3K in a heart-specific manner were analyzed at the ages of 3 and 20 months. Effects of persistent activation of PI3K on gene expression were comprehensively analyzed using microarrays.Key findingsUpon comprehensive gene expression profiling, the genes whose expression was increased included those for several heat shock chaperons. The amount and nuclear localization of a forkhead box O (FOXO) protein was increased. In addition, the gene expression of insulin receptor substrate-2 decreased, and that of phosphatase and tensin homolog deleted on chromosome ten (PTEN) increased, suggesting that the persistent activation of PI3K modified the expression of molecules of insulin/IGF-1 signaling. The expression of markers of cellular senescence, such as senescence-associated beta-galactosidase activity, cell cycle inhibitors, proinflammatory cytokines, and lipofuscin, did not differ between old wild-type and caPI3K mice.SignificanceThe persistent activation of PI3K modified the expression of molecules of insulin/IGF-1 signaling pathway in a transgenic mouse line. Markers of cellular senescence were not changed in the aged mutant mice.     

Assessment of border control measures and community containment measures used in Japan during the early stages of Pandemic (H1N1) 2009

Background

In the early stages of Pandemic (H1N1) 2009, border control measures were taken by quarantine stations to block the entry of infected individuals into Japan and community containment measures were implemented to prevent the spreading. The objectives of this study were to describe these measures and the characteristics of infected individuals, and to assess the measures'' effectiveness.

Methodology/Principal Findings

Border control and community containment measures implemented from April to June (Period I: April 28–May 21, Period II: May 22–June 18) 2009 were described. Number of individuals identified and disease characteristics were analyzed. For entry screening, a health declaration form and an infrared thermoscanner were used to detect symptomatic passengers. Passengers indicated for the rapid influenza test underwent the test followed by RT-PCR. Patients positive for H1N1 were isolated, and close contacts were quarantined. Entry cards were handed out to all asymptomatic passengers informing them about how to contact a health center in case they developed symptoms. Nine individuals were identified by entry screening and 1 during quarantine to have Pandemic (H1N1) 2009. Health monitoring by health centers was performed in period I for passengers arriving from affected countries and in period II for those who had come into contact with the individuals identified by entry screening. Health monitoring identified 3 infected individuals among 129,546 in Period I and 5 among 746 in Period II. Enhanced surveillance, which included mandatory reporting of details of the infected individuals, identified 812 individuals, 141 (18%) of whom had a history of international travel. Twenty-four of these 141 passengers picked up by enhanced surveillance had been developing symptoms on entry and were missed at screening.

Conclusion/Significance

Symptomatic passengers were detected by the various entry screening measures put in place. Enhanced surveillance provided data for the improvement of public health measures in future pandemics.     

Neural correlates of the difference between working memory speed and simple sensorimotor speed: an fMRI study

The difference between the speed of simple cognitive processes and the speed of complex cognitive processes has various psychological correlates. However, the neural correlates of this difference have not yet been investigated. In this study, we focused on working memory (WM) for typical complex cognitive processes. Functional magnetic resonance imaging data were acquired during the performance of an N-back task, which is a measure of WM for typical complex cognitive processes. In our N-back task, task speed and memory load were varied to identify the neural correlates responsible for the difference between the speed of simple cognitive processes (estimated from the 0-back task) and the speed of WM. Our findings showed that this difference was characterized by the increased activation in the right dorsolateral prefrontal cortex (DLPFC) and the increased functional interaction between the right DLPFC and right superior parietal lobe. Furthermore, the local gray matter volume of the right DLPFC was correlated with participants' accuracy during fast WM tasks, which in turn correlated with a psychometric measure of participants' intelligence. Our findings indicate that the right DLPFC and its related network are responsible for the execution of the fast cognitive processes involved in WM. Identified neural bases may underlie the psychometric differences between the speed with which subjects perform simple cognitive tasks and the speed with which subjects perform more complex cognitive tasks, and explain the previous traditional psychological findings.     

An inducible RNA interference system in Physcomitrella patens reveals a dominant role of augmin in phragmoplast microtubule generation

Mitosis is a fundamental process of eukaryotic cell proliferation. However, the molecular mechanisms underlying mitosis remain poorly understood in plants partly because of the lack of an appropriate model cell system in which loss-of-function analyses can be easily combined with high-resolution microscopy. Here, we developed an inducible RNA interference (RNAi) system and three-dimensional time-lapse confocal microscopy in the moss Physcomitrella patens that allowed in-depth phenotype characterization of the moss genes essential for cell division. We applied this technique to two microtubule regulators, augmin and γ-tubulin complexes, whose mitotic roles remain obscure in plant cells. Live imaging of caulonemal cells showed that they proceed through mitosis with continual generation and self-organization of acentrosomal microtubules. We demonstrated that augmin plays an important role in γ-tubulin localization and microtubule generation from prometaphase to cytokinesis. Most evidently, microtubule formation in phragmoplasts was severely compromised after RNAi knockdown of an augmin subunit, leading to incomplete expansion of phragmoplasts and cytokinesis failure. Knockdown of the γ-tubulin complex affected microtubule formation throughout mitosis. We conclude that postanaphase microtubule generation is predominantly stimulated by the augmin/γ-tubulin machinery in moss and further propose that this RNAi system serves as a powerful tool to dissect the molecular mechanisms underlying mitosis in land plants.