Scanning sonar of rolling porpoises during prey capture dives

Dolphins and porpoises have excellent biosonar ability, which they use for navigation, ranging and foraging. However, the role of biosonar in free-ranging small cetaceans has not been fully investigated. The biosonar behaviour and body movements of 15 free-ranging finless porpoises (Neophocaena phocaenoides) were observed using electronic tags attached to the animals. The porpoises often rotated their bodies more than 60 deg., on average, around the body axis in a dive bout. This behaviour occupied 31% of the dive duration during 186 h of effective observation time. Rolling dives were associated with extensive searching effort, and 23% of the rolling dive time was phonated, almost twice the phonation ratio of upright dives. Porpoises used short inter-click interval sonar 4.3 times more frequently during rolling dives than during upright dives. Sudden speed drops, which indicated that an individual turned around, occurred 4.5 times more frequently during rolling dives than during upright dives. Together, these data suggest that the porpoises searched extensively for targets and rolled their bodies to enlarge the search area by changing the narrow beam axis of the biosonar. Once a possible target was detected, porpoises frequently produced short-range sonar sounds. Continuous searching for prey and frequent capture trials appeared to occur during rolling dives of finless porpoises. In contrast, head movements ranging ±2 cm, which can also change the beam axis, were regularly observed during both dives. Head movements might assist in instant assessment of the arbitrary direction by changing the beam axis rather than prey searching and pursuit.

Evidence for internal structures of spiral turbulence

We present several observations into spiral turbulence in a Taylor-Couette geometry gained through a three-dimensional direct numerical simulation. Conditionally averaged flow statistics show the persistence of an azimuthal gradient of the mean flow across both the turbulent and laminar spirals, and distinct distribution features of the turbulent intensity. The data provide a physical picture qualitatively different from the existing model of spiral turbulence. Certain aspects of the spiral pattern are observed to bear similarities to the stationary laminar-turbulent pattern in plane Couette flow.

In vitro sequence-dependent interaction between paclitaxel and gefitinib in human lung cancer cell lines

e22025

Background: Cytotoxicity chemotherapy has been standard first line treatment for advanced NSCLC. Clinical trials comparing first line EGFR TKI therapy over cytotoxicity chemotherapy are under investigation in phase III trials. The aim of this study is to test the hypothesis that paclitaxel followed by gefitinib would be superior to the opposite order in EGFR TKI resistant cell lines because of cell signaling pathway and cell cycle interaction. Methods: we have used EGFR-TKI resistant human lung cancer cell lines A549, H1975 and H1650 as an in vitro model for defining the differential effects of opposite sequence of combination of cytotoxic drug and anti- EGFR agents on cell growth, signaling pathway, cell cycle distribution and induction of apoptosis. Results: Paclitaxel 24 hours followed by gefitinib 72 hours in A549, H1975 and H1650 cells produced synergistic effects, while the reverse sequence produced antagonistic effects. Exposure to paclitaxel resulted in an increased pEGFR and pAKT level, this increase of phosphorylation can be inhibited by the following gefitinib exposure, while the reverse sequence resulted in no change in EGFR and AKT phosphorylation. We confirmed that gefitinib arrested the cells in G1, paclitaxel arrested cells in S phase. The sequence of paclitaxel followed by gefitinib cause cells arrested in G1, while the reverse sequence cause cells arrested in S and G2 phase. Conclusions: These findings suggest that the sequence of paclitaxel followed by gefitinib may be superior to the reverse sequence in gefitinib resistant NSCLC, and support the investigation of these sequential treatment in the clinical setting. This work was supported by the grants from the National Natural Science Foundation of China (No. 30772531).

No significant financial relationships to disclose.

Kinetic analysis of experimental rabbit tumour and inflammation model with 18F-FDG PET/CT

Non-specific accumulation of 18F-FDG by both tumour and inflammatory lesions can make diagnostic analysis difficult. Our aim was to explore the difference in 18F-FDG uptake kinetics between tumour and inflammatory cells. To this end, we investigated VX2 tumour lesions and inflammatory lesions in rabbits.

METHODS

Six rabbits with VX2 tumour cells transplanted into one forelimb muscle and inflammatory lesions induced by turpentine oil in the contralateral forelimb were scanned for 60 minutes post 18F-FDG injection. Imaging data was analyzed with the standard 2-tissue-compartment model. Parameters, VB, Ki, K1, k2, k3, k4, were compared between tumour and inflammatory lesions. SUV and dual time scan methods were also compared in the experiment.

RESULTS

Time activity curves of VX2 tumour lesions showed a characteristic pattern of gradually increasing 18F-FDG uptake up to 60 min, whereas, 18F-FDG uptake in inflammatory lesions increased more slowly than in tumours. Parameters estimated from the uptake process showed that forward transport constant, K1, and influx constant, Ki, values in VX2 tumour lesions (0.186 +/- 0.053 and 0.048 +/- 0.014, respectively) was significantly higher than that in inflammatory lesions (0.129 +/- 0.024 and 0.022 +/- 0.007, respectively) (p < 0.05). In contrast, mean values of VB, k2, k3 and k4 derived from VX2 tumours were not significantly different from that of inflammatory lesions. SUVs at 60 minutes post 18F-FDG injection were also significantly higher in the VX2 tumor lesions than in the inflammatory lesions. Retention index (RI) was not significantly different between VX2 tumours and inflammatory lesions (1.134 +/- 0.076 vs. 1.060 +/- 0.058, p > 0.05).

CONCLUSION

Different kinetic parameters (Ki, K1, k3) exist between inflammatory and tumour lesions.

Partial dissociation of molecular and behavioral measures of song habituation in adult zebra finches

Initial playback of recorded birdsong triggers a number of responses in zebra finches, including overt listening behavior and ERK pathway-dependent activation of zenk gene transcription in the auditory lobule of the forebrain. Repetition of one song stimulus leads to persistent habituation of these responses, as measured by subsequent presentations 1 day later. In this study, we examined the causal relationships between behavioral and molecular (ERK/zenk) habituation. In a within-subject comparison, we found a strong correlation with the level of prior training for both responses (duration of behavioral listening and magnitude of zenk expression), but little correlation between these responses for birds within the same treatment group. We then tested the hypothesis that ERK/zenk activation during training is necessary for the development of habituation measured 1 day later. Cannula-directed infusion of a pharmacological inhibitor of ERK activation (U0126) immediately before training blocked the development of habituation of the zenk gene response. However, measurement of the effect on behavioral habituation was confounded because birds that were infused with a non-active drug analogue (U0124) showed a decreased response 1 day later, even to novel songs. We conclude that the behavioral response to song stimulation is strongly influenced by factors other than song familiarity, whereas the zenk response in the forebrain may be a more accurate indicator of actual experience hearing a particular song.

Estimation of the detection probability for Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) with a passive acoustic method

Yangtze finless porpoises were surveyed by using simultaneous visual and acoustical methods from 6 November to 13 December 2006. Two research vessels towed stereo acoustic data loggers, which were used to store the intensity and sound source direction of the high frequency sonar signals produced by finless porpoises at detection ranges up to 300 m on each side of the vessel. Simple stereo beam forming allowed the separation of distinct biosonar sound source, which enabled us to count the number of vocalizing porpoises. Acoustically, 204 porpoises were detected from one vessel and 199 from the other vessel in the same section of the Yangtze River. Visually, 163 and 162 porpoises were detected from two vessels within 300 m of the vessel track. The calculated detection probability using acoustic method was approximately twice that for visual detection for each vessel. The difference in detection probabilities between the two methods was caused by the large number of single individuals that were missed by visual observers. However, the sizes of large groups were underestimated by using the acoustic methods. Acoustic and visual observations complemented each other in the accurate detection of porpoises. The use of simple, relatively inexpensive acoustic monitoring systems should enhance population surveys of free-ranging, echolocating odontocetes.

Elimination of vortex streets in bluff-body flows

We present an effective technique for suppressing the vortex-induced vibrations of bluff bodies by eliminating the von Kármán street formed in their wake. Specifically, we find that small amounts of combined windward suction and leeward blowing around the body modify the wake instability and lead to suppression of the fluctuating lift force. Three-dimensional simulations and stability analysis are employed to quantify our findings for the flow past fixed and flexibly mounted circular cylinders.

Association of misconceptions about HIV transmission and discriminatory attitudes in rural China

This study examined HIV-related knowledge and attitudes among 524 randomly selected adult residents from 12 rural Chinese communities where HIV infection among plasma donors has been reported. Most participants were familiar with the main routes of HIV transmission but had substantial misconceptions about risk of HIV transmission through casual social contacts. Higher score of misconception and being older and married independently predicted stronger discriminatory attitude. Intervention programs with focus on eliminating misconceptions about HIV transmission may reduce stigma.

Herringbone streaks in Taylor-Couette turbulence

We study near-wall streaks that form herringbonelike patterns in Taylor-Couette turbulence and in counter-rotating Taylor-Couette turbulence through three-dimensional direct numerical simulations. The orientation, axial distribution, onset, and tilting angle of these streaks are characterized.

Resonant vibrations of bluff bodies cause multivortex shedding and high frequency forces

A flexibly mounted circular cylinder in cross-flow, with natural frequencies in the inline and transverse directions having a ratio close to 2:1, exhibits drastic changes in the vortex structures in its wake, the frequency content of the fluid forces, and the orbital shape of its resulting motions. Stable multivortex patterns form in the cylinder wake, associated with large high-frequency force components.

Physical and functional interaction of Runt-related protein 1 with hypoxia-inducible factor-1alpha

Angiogenesis and hematopoiesis are closely linked and interactive with each other, but few studies were given to identify possible links between angiogenesis-promoting proteins and hematopoiesis-related transcription factors. Here we investigated the potential relationship of oxygen-sensitive alpha-subunit of angiogenesis-related hypoxia-inducible factor-1alpha (HIF-1alpha) with Runt-related protein 1 (Runx1, also known as acute myeloid leukemia-1, AML-1), an important hematopoietic transcription factor. The results demonstrated that Runx1 and HIF-1alpha proteins directly interacted with each other to a degree, in which Runt homology domain of Runx1 was mainly involved. Leukemia-related abnormal Runx1 fusion protein AML1-ETO, which fuses the N-terminal 177 amino acid residues of the Runx1 protein in frame to ETO (eight-twenty-one) protein, also interacted with HIF-1alpha protein with greater ability than Runx1 itself. More intriguingly, Runx1 overexpression inhibited DNA-binding and transcriptional activity of HIF-1 protein with reduced expression of HIF-1-targeted genes such as vascular endothelial growth factor, while silence of Runx1 expression by specific small interfering RNA significantly increased transcriptional activity of HIF-1 protein, suggesting that Runx1 inhibited transcription-dependent function of HIF-1. Vice versa, HIF-1alpha increased DNA-binding ability and transcriptional activity of Runx1 protein. All these data would shed new insight to understanding Runx1 and HIF-1alpha-related hematopoietic cell differentiation and angiogenesis.

Increased calcium deposits and decreased Ca2+-ATPase in right ventricular myocardium of ascitic broiler chickens

Right ventricular hypertrophy and failure is an important step in the development of ascites syndrome (AS) in broiler chickens. Cytoplasmic calcium concentration is a major regulator of cardiac contractile function and various physiological processes in cardiac muscle cells. The purpose of this study was to measure the right ventricular pressure and investigate the precise ultrastructural location of Ca(2+) and Ca(2+)-ATPase in the right ventricular myocardium of chickens with AS induced by low ambient temperature. The results showed that the right ventricular diastolic pressure of ascitic broilers was significantly higher than that of control broilers (P < 0.01), and the maximum change ratio of right intraventricular pressure (RV +/- dp/dt(max)) of ascitic broilers was significantly lower than that of the controls (P < 0.01). Extensively increased calcium deposits were observed in the right ventricular myocardium of ascitic broilers, whereas in the age-matched control broilers, calcium deposits were much less. The Ca(2+)-ATPase reactive products were obviously found on the sarcoplasmic reticulum and mitochondrial membrane of the control right ventricular myocardium, but rarely observed in the ascitic broilers. The data suggest that in ascitic broilers there is the right ventricular diastolic dysfunction, in which the overload of intracellular calcium and the decreased Ca(2+)-ATPase activity might be the important factors.

Electric field induced collapse of the charge-ordered phase in manganites

The colossal electroresistance in manganites accompanies the insulator-to-metal phase transition induced by the electric field. A phenomenological phase transition model is proposed to study this electric field induced collapse of the charge-ordered phase. The hysteresis of the phase transition is well explained using the effective medium approximation. The volume fraction of the metallic region at the metal-to-insulator transition point is estimated as 30%.

B7-H1 expression is upregulated in peripheral blood CD14+ monocytes of patients with chronic hepatitis B virus infection, which correlates with higher serum IL-10 levels

Chronicity in hepatitis B virus (HBV) infection is maintained by increased type 2 T-helper cell response, possibly because of increased interleukin-10 (IL-10) productions. B7-H1 can negatively regulate T-cell responses via its receptor, programmed death 1. Ligation of B7-H1 to T-cells can result in the preferential secretion of IL-10. In this study, we investigated whether there was an upregulated expression of B7-H1 in peripheral blood mononuclear cells in patients chronically infected by HBV and further explored the correlation between B7-H1 expression and serum interleukin 2, interferon-gamma, IL-10, HBeAg, alanine aminotransferase (ALT) levels and viral load. Fifty-five patients with chronic HBV infection and 20 healthy controls (HCs) were enrolled in the present study. The results showed that in patients with chronic hepatitis B CD14+ monocytes but not CD3+ and CD19+ cells had a significantly increased expression of B7-H1 compared with HCs, which positively correlates with serum IL-10 levels and the presence of HBeAg and negatively correlates with serum ALT levels. In conclusion, chronic HBV patients harbour an increased B7-H1 expression in CD14+ monocytes compared with controls, which may be responsible for the increased serum IL-10 levels. This might be an important way by which HBV evades an adequate immune response, leading to viral persistence and disease chronicity.

Mycophenolic Acid Upregulates B7-DC Expression on Dendritic Cells, Which Is Associated With Impaired Allostimulatory Capacity of Dendritic Cells

In addition to its effects on lymphocytes, mycophenolic acid (MPA) may inhibit the allostimulatory capacity of dendritic cells (DC) via unknown mechanisms. B7-H1 and B7-DC surface markers on DC negatively regulate T-cell responses via the receptor PD-1. In this study, we sought to investigate whether B7-H1 and B7-DC are responsible for the inhibitory functions of MPA on DC. Mouse bone marrow-derived DC were cultured with recombinant granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 in the presence or absence of MPA (0.01 micromol and 0.1 micromol). The DC phenotype was assessed by flow cytometry, their immunostimulatory capacity measured by mixed lymphocyte reaction (MLR), and cytokine production by ELISA. The results showed that MPA not only inhibited the expression of major histocompatibility complex (MHC) class II and costimulatory molecules CD80 and CD86 but upregulated B7-DC expression on mature DC induced by LPS. These findings were associated with a reduced allostimulatory ability and an altered cytokine secretion pattern of DC. Thus, we suggest that MPA upregulates B7-DC expression during DC maturation induced by LPS in vitro, an effect that may be responsible for MPA-mediated inhibitory effects on the allostimulatory capacity of DC.

Aberrant termination triggers nonsense-mediated mRNA decay

NMD (nonsense-mediated mRNA decay) is a cellular quality-control mechanism in which an otherwise stable mRNA is destabilized by the presence of a premature termination codon. We have defined the set of endogenous NMD substrates, demonstrated that they are available for NMD at every round of translation, and showed that premature termination and normal termination are not equivalent biochemical events. Premature termination is aberrant, and its NMD-stimulating defects can be reversed by the presence of tethered poly(A)-binding protein (Pab1p) or tethered eRF3 (eukaryotic release factor 3) (Sup35p). Thus NMD appears to be triggered by a ribosome's failure to terminate adjacent to a properly configured 3'-UTR (untranslated region), an event that may promote binding of the UPF/NMD factors to stimulate mRNA decapping.

Decreased intranuclear mobility of acute myeloid leukemia 1-containing fusion proteins is accompanied by reduced mobility and compartmentalization of core binding factor beta

Acute myeloid leukemia 1 (AML1) gene on chromosome 21 is involved in several chromosomal translocations, including t(8;21) and t(16;21), that produce chimeric fusion proteins AML1-eight twenty-one (ETO) and AML-myeloid transforming gene chromosome 16 (MTG16), which contribute to leukemogenesis. The molecular basis for the leukemogenic effects of these fusion proteins is incompletely understood. Using gel-shift assay, we showed that AML1-ETO and AML1-MTG16 bound to a series of AML1 consensus DNA-binding sites with different affinities. Using fluorescence recovery after photobleaching (FRAP), we demonstrated that a fusion of AML1 with ETO or MTG16 exhibits reduced intranuclear mobility compared with wild-type AML1 or either fusion partner. The dimerization domain (nervy homology region 2) of ETO is responsible for the reduced mobility of AML1-ETO. Dual FRAP studies revealed that CBFbeta colocalized with AML1-ETO within the nucleus, resulting in reduced mobility of CBFbeta. Therefore, AML1 fusion proteins may interfere with normal AML1 function due to aberrant nuclear dynamics, which leads to spatial and temporal sequestration of CBFbeta and perhaps other coregulators critical for myeloid differentiation.

Morphological alteration and biological properties of hepatocytes not related to tumorigenesis following transfection with HCV core protein

The hepatitis C virus (HCV) core protein is supposed to play a critical role in HCV-mediated human liver disease with its capabilities to regulate the growth rate of hepatocytes and to partially contribute to the pathogenesis of hepatocellular carcinoma in association with cellular oncogenes. In this study, to analyse the possible pathological mechanism of the HCV core protein, human primary embryo hepatocytes transfected with HCV core were monitored by immunofluorescence, reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot. The morphological changes and biological properties of the transfected hepatocytes were also studied. The results showed that the HCV core gene integrated in the cellular genome and the protein expressed in the transfected hepatocyte, could be detected following serial passage at both the mRNA and protein level. The proliferation assays indicated that hepatocytes transfected with the HCV core gene alone did not exhibit any tumorigenic tendency. Meanwhile, the morphological alterations of these cells demonstrated obvious changes in size, and large vacuolar degeneration. In conclusion, the hepatocytes transfected with the HCV core gene revealed that the core protein expressed induced pathological changes of degeneration, probably related indirectly to tumorigenicity.

Identification of a novel human sand family protein in human fibroblasts induced by herpes simplex virus 1 binding

Studies on interaction between Herpes simplex virus 1 (HSV-1) and human fibroblasts KMB-17 have demonstrated that HSV-1 binding to the cell surface could induce a specific gene response. In this study, the HSV-1 stimulation-related gene 1 (HSRG1), a new so far unknown gene function of cellular response induced by a specific stimulation with HSV-1, was cloned from the cDNA library established from mRNA of early gene response of KMB-17 cells. The gene product consisted of 547 amino acids and had a significant homology, in six eukaryotic species. On the basis of its structure it was identified as a member of the SAND protein family. The HSRG1 protein was fused with glutathione S-transferase (GST) and expressed in Escherichia coli DHPalpha strain under the control of T7 promoter. An antibody to HSRG1 raised in mice was used to detect expression of the HSRG1 protein in KMB-17 cells stimulated by HSV-1 by an immunoprecipitation assay. It was found that the HSRG1 protein was induced in these cells by HSV-1 at high level.

Electrochemistry and spectroscopy study on the interaction of microperoxidase-11 with lipid membrane

The interaction of microperoxidase-11 (MP11) with cationic lipid vesicles of didodecyldimethylammonium bromide (DDAB) induces an alpha-helical conformation from random coil conformations in solution and this change then makes heme macrocycle more distorted. DDAB-induced MP11 conformations were investigated by cyclic votammetry (CV), circular dichroism (CD) and UV-vis spectrometry. All results indicate that the binding of MP11 in solution to DDAB vesicles and the ordered structure formation are driven by mostly electrostatic interaction between negatively charged residues in the undecapeptide and positively charged lipid headgroups on the membrane surface. Upon binding to DDAB, its half-peak potential was also changed. The mechanism of the interaction between MP11 and DDAB was also discussed.