Chronic microstimulation of cat auditory cortex effective to evoke detection behaviors

The purpose of this study was to clarify stimulus pulse parameters effective to elicit behaviors of cats trained to detect electric pulse stimuli through chronically implanted electrodes in the primary auditory cortex. One or two pulse parameters were systematically shifted from the standard stimulus consisting of constant-current pulses of amplitude 80 μA, duration 0.2 ms, number of pulses 33, and rate 200 Hz (compatible with interpulse interval 5 ms). Interaction between the pulse amplitude and pulse duration was investigated: although the proportion of stimulus detection responses increased with increasing phase charge (pulse amplitude×pulse duration), a combination of relatively high amplitude during short pulse duration elicited a higher proportion of detection responses when phase charge was constant. Interaction between the number of pulses and interpulse intervals was investigated. We found that the proportion of detection responses is explained by the linear function of two factors, overall charge (phase charge×the number of pulses) and train duration: the proportion of detection responses increased with increasing overall charge and decreasing train duration. Interaction between pulse amplitude and the number of pulses was investigated. We again found that the proportion of detection responses is explained by the linear function of overall charge and train duration in the amplitude-number shift paradigm. Thus, the behavior performance (proportion of detection responses) is a linear time function of overall charge and train duration regardless of the stimulus paradigm. We believe that the findings will contribute to the development of auditory cortex implants for transfer of auditory information directly to the brain.

Ultrafast soft X-ray photoelectron spectroscopy at liquid water microjets

Since the pioneering work of Kai Siegbahn, electron spectroscopy for chemical analysis (ESCA) has been developed into an indispensable analytical technique for surface science. The value of this powerful method of photoelectron spectroscopy (PES, also termed photoemission spectroscopy) and Siegbahn's contributions were recognized in the 1981 Nobel Prize in Physics. The need for high vacuum, however, originally prohibited PES of volatile liquids, and only allowed for investigation of low-vapor-pressure molecules attached to a surface (or close to a surface) or liquid films of low volatility. Only with the invention of liquid beams of volatile liquids compatible with high-vacuum conditions was PES from liquid surfaces under vacuum made feasible. Because of the ubiquity of water interfaces in nature, the liquid water-vacuum interface became a most attractive research topic, particularly over the past 10 years. PES studies of these important aqueous interfaces remained significantly challenging because of the need to develop high-pressure PES methods. For decades, ESCA or PES (termed XPS, for X-ray photoelectron spectroscopy, in the case of soft X-ray photons) was restricted to conventional laboratory X-ray sources or beamlines in synchrotron facilities. This approach enabled frequency domain measurements, but with poor time resolution. Indirect access to time-resolved processes in the condensed phase was only achieved if line-widths could be analyzed or if processes could be related to a fast clock, that is, reference processes that are fast enough and are also well understood in the condensed phase. Just recently, the emergence of high harmonic light sources, providing short-wavelength radiation in ultrashort light pulses, added the dimension of time to the classical ESCA or XPS technique and opened the door to (soft) X-ray photoelectron spectroscopy with ultrahigh time resolution. The combination of high harmonic light sources (providing radiation with laserlike beam qualities) and liquid microjet technology recently enabled the first liquid interface PES experiments in the IR/UV-pump and extreme ultraviolet-probe (EUV-probe) configuration. In this Account, we highlight features of the technology and a number of recent applications, including extreme states of matter and the discovery and detection of short-lived transients of the solvated electron in water. Properties of the EUV radiation, such as its controllable polarization and features of the liquid microjet, will enable unique experiments in the near future. PES measures electron binding energies and angular distributions of photoelectrons, which comprise unique information about electron orbitals and their involvement in chemical bonding. One of the future goals is to use this information to trace molecular orbitals, over time, in chemical reactions or biological transformations.

Abnormal male meiosis explains pollen sterility in the polyploid medicinal plant Pinellia ternata (Araceae)

Pinellia ternata is an important traditional Chinese medicinal plant. Its different populations in China have various ploidy levels, based on x = 13, as well as extensive aneuploid series. The microsporogenesis process was observed in specimens from three populations from three regions of Hubei Province; they were characterized by normal and abnormal meiotic divisions in pollen mother cells (PMCs) at all stages simultaneously. Meiotic abnormalities including univalents/multivalents, chromosomal laggards/bridges and micronuclei appeared in about 50% of the PMCs, together with abnormal cytokinesis. Chromatin/chromosome transfer between meiocytes occurred only during the first division, at low frequency; this might contribute to these meiotic abnormalities. Although the remaining 50% of the PMCs presented normal cytological behavior, pollen fertility was only about 2%. These results provide cytological explanations for its low seed-set and the general use of asexual reproduction through tubers and bulbils; it also explains the wide variations in chromosome number.

An EUV beamsplitter based on conical grazing incidence diffraction

We present an innovative grating design based on conical diffraction which acts as an almost perfect and low-loss beamsplitter for extreme ultraviolet radiation. The scheme is based on a binary profile operated in grazing incidence along the grating bars under total external reflection. It is shown that periods of a few 10(2) nm may permit an exclusive (±1)(st) order diffraction with efficiencies up to ~ 35% in each of them, whereas higher evanescent orders vanish. In contrast, destructive interference eliminates the 0(th) order. For a sample made of SiO(2) on silicon, measured data and simulated results from rigorous coupled wave analysis procedures are given.

Search for doubly charged Higgs boson pair production in pp¯ collisions at √s=1.96 TeV

We present a search for pair production of doubly charged Higgs bosons in the processes qq¯→H(++)H(--) decaying through H(±±)→τ(±)τ(±),μ(±)τ(±),μ(±)μ(±). The search is performed in pp¯ collisions at a center-of-mass energy of √s = 1.96 TeV using an integrated luminosity of up to 7.0 fb(-1) collected by the D0 experiment at the Fermilab Tevatron Collider. The results are used to set 95% C.L. limits on the pair production cross section of doubly charged Higgs bosons and on their mass for different H(±±) branching fractions. Models predicting different H(±±) decays are investigated. Assuming B(H(±±)→τ(±)τ(±))=1 yields an observed (expected) lower limit on the mass of a left-handed H(L)(±±) boson of 128 (116) GeV and assuming B(H(±±)→μ(±)τ(±))=1 the corresponding limits are 144 (149) GeV. In a model with B(H(±±)→τ(±)τ(±))=B(H(±±)→μ(±)τ(±))=B(H(±±)→μ(±)μ(±))=1/3, we obtain M(H(L)(±±))>130 (138) GeV.

White matter abnormalities are related to microstructural changes in preterm neonates at term-equivalent age: a diffusion tensor imaging and probabilistic tractography study

BACKGROUND AND PURPOSE

Preterm infants have a high risk of brain injury and neurodevelopmental impairment, often associated with WMA on conventional MR imaging. DTI can provide insight into white matter microstructure. The aim of this study was to investigate the association between WMA on conventional MR imaging and DTI parameters in specific fibers in preterm neonates at term-equivalent age.

MATERIALS AND METHODS

Seventy preterm neonates (39 boys and 31 girls) were included in the study. WMA were classified as no, mild, moderate, or severe. Probabilistic tractography provided tract volumes, FA, MD, λ(//), and λ(⊥) in the CST, SLF, TRs, and corpus callosum. Data were compared by using MANOVA, and adjustment for multiple comparisons was performed.

RESULTS

Important associations were found between WMA and microstructural changes. Compared with neonates with no WMA (n = 41), those with mild WMA (n = 27) had significantly increased λ(⊥) and MD in the left ATR, the left sensory STR, the bilateral motor STR, and for λ(⊥) also in the right CST; FA decreased significantly in the left sensory STR. Diminished tract volumes and altered diffusion indices were also observed in the 2 neonates with moderate WMA.

CONCLUSIONS

Altered DTI indices in specific tracts, with λ(⊥) as most prominent, are associated with mild WMA in preterm neonates at term-equivalent age.

Simultaneous measurement of adenosine triphosphate release and aggregation potentiates human platelet aggregation responses for some subjects, including persons with Quebec platelet disorder

Platelet aggregometry and dense granule adenosine triphosphate (ATP) release assays are helpful to diagnose platelet disorders. Some laboratories simultaneously measure aggregation and ATP release using Chronolume® a commercial reagent containing D-luciferin, firefly luciferase and magnesium. Chronolume® can potentiate sub-maximal aggregation responses, normalising canine platelet disorder findings. We investigated if Chronolume® potentiates human platelet aggregation responses after observing discrepancies suspicious of potentiation. Among patients simultaneously tested by light transmission aggregometry (LTA) on two instruments, 18/43 (42%), including 14/24 (58%) with platelet disorders, showed full secondary aggregation with one or more agonists only in tests with Chronolume®. As subjects with Quebec platelet disorder (QPD) did not show the expected absent secondary aggregation responses to epinephrine in tests with Chronolume®, the reason for the discrepancy was investigated using samples from 10 QPD subjects. Like sub-threshold ADP (0.75 μM), Chronolume® significantly increased QPD LTA responses to epinephrine (p<0.0001) and it increased both initial and secondary aggregation responses, leading to dense granule release. This potentiation was not restricted to QPD and it was mimicked adding 1-2 mM magnesium, but not D-luciferin or firefly luciferase, to LTA assays. Chronolume® potentiated the ADP aggregation responses of QPD subjects with a reduced response. Furthermore, it increased whole blood aggregation responses of healthy control samples to multiple agonists, tested at concentrations used for the diagnosis of platelet disorders (p values <0.05). Laboratories should be aware that measuring ATP release with Chronolume® can potentiate LTA and whole blood aggregation responses, which alters findings for some human platelet disorders, including QPD.

Cell cycle arrest of Jurkat cells by leukemic bone marrow stromal cells: possible mechanisms and involvement of CRIF1

Bone marrow hemopoietic microenvironment plays an important role in the incidence and development of leukemia. Studies using normal bone marrow stromal cells (BMSCs) and an established stromal cell line, have shown that the leukemic cell cycle can be arrested in the G0/G1 phase in BMSCs, although the mechanism is still unclear. We performed this study to determine the effect of primary cultured leukemic BMSCs on the cell cycle distribution of Jurkat cells. Normal and leukemic BMSCs were isolated for culture to create a hematopoietic microenvironment simulating bone marrow in vitro. The normal and leukemic BMSCs induced cell cycle arrest of Jurkat cells in the G0/G1 phase. Suppression subtractive hybridization revealed differential gene expression after the co-culture of cells with normal and leukemic BMSCs. Jurkat cells showed upregulated expression of genes involved in cell cycle control CR6 interacting factor 1 (CRIF1). Reverse transcriptase polymerase chain reaction results also showed increased CRIF1 mRNA levels in Jurkat cells co-cultured with either normal BMSCs or leukemic BMSCs compared with a suspension culture group: 5.16 ± 0.75, 6.13 ± 0.63 versus 3.02 ± 0.32, respectively (P < .05). These results indicated cell cycle arrest of Jurkat cells in the G0/G1 phase to be induced by primary cultured leukemic BMSCs associated with increased expression of CRIF1 by leukemic cells.

Exosomes and immune surveillance of neoplastic lesions: a review

The immune system has been reported to suppress the development and progression of neoplastic lesions; however, the exact mechanisms by which neoplastic lesions and the immune system interact are not well understood. Within the last decade, tiny membrane bound particles, approximately 30-100 nm in diameter, have been observed in the blood and other body fluids. These particles, currently called exosomes, are released from many types of tissues including tumors, and they contain and carry many proteins, and mRNAs and microRNA species. We review here how tumors suppress the immune system, especially by the formation of exosomes. Exosomes released from tumors are carried in part by the vascular system to distant cells, which phagocytose them. Depending on the proteins, mRNAs or microRNAs in the exosomes and the cell type, phagocytosis of exosomes may provide a modulating signal to the cell. In the case of exosomes from tumors, uptake of the exosomes by cells of the immune system has been reported to have three main effects: 1) suppression of the number and activity of natural killer cells, 2) suppression of the activity of T cells and 3) suppression of the number and maturation of mature dendritic cells.

Finite element model of spinal hemiepiphysiodesis: effect of contact conditions, initial conditions, and growth

Growth modification is under investigation to treat pediatric spine deformities. A hemiepiphyseal staple construct has been shown to alter growth and create physeal structural gradients in an in vivo porcine model. A finite element model (FEM) of a motion segment with and without implant was developed based on preliminary experimental results of initial post-operative motion segment compressive properties. The nonlinear tangent stiffness determined from the model correlated well with the experiments for the native segment, whereas after addition of the implant, the model overestimated the stiffness. The current purpose was to determine the effect of implant-bone contact conditions and initial disc displacement conditions, include growth effects, and compare FEM and experimental results at each stage. A 3D FEM was developed from a CT scan of a porcine T7-T8 segment. The annulus was modeled as an incompressible anisotropic hyperelastic material, and the nucleus as an incompressible fluid. A CAD model of the implant was constructed. Load-displacement curves in compression were determined from a nonlinear analysis performed under different initial and bone-implant interface conditions. Contact conditions were a) perfect, b) friction of 0.1-0.3, or c) soft contact. Initial conditions were that implant insertion induced a) no change in stress or strain in the disc, b) a 2˚ angulation with a centrally located neutral axis and no residual stresses, and c) both stress and coronal plane displacement gradients. Growth modulation effects were added using a published linear relationship between compressive stress and growth rate. A 2 month PO time was simulated. Altering bone - implant surface contact conditions from perfect to either friction or soft contact decreased the stiffness, but all models remained stiffer than experimental results. An initial disc angulation without residual stress did not affect stiffness, whereas stiffness increased with an initial angle and compressive stress. The growth simulation results predicted 32% of control growth on the side ipsilateral to the implant and 81% on the contralateral side. Reductions in growth were similar in pattern, but overestimated, experimental histomorphometric changes.

Targeting glioblastoma stem cells: cell surface markers

Glioblastoma multiforme (GBM) is the most common primary brain tumor and among the most lethal cancers. There is increasing evidence that cancer stem cells within GBMs, which are often referred to as glioblastoma stem cells (GSCs), play a critical role in tumor initiation and maintenance. Identification of novel markers for GSCs will lead to better targeting of GSCs which could have tremendous impact on treatment of GBMs. Cell surface markers are particularly suitable as therapeutic targets. Although several promising cell surface markers have successfully been used for enrichment of GSCs, their functional roles in maintenance of GSC properties as well as in GBM formation and development remain to be characterized. In this review, we primarily summarize recent advances in identification of GSC markers, with a particular focus on cell surface markers.

21 EFFECT OF SECOND TIME XENOPUS EGG EXTRACT TREATMENT ON COLONY FORMATION AND CLONED BLASTOCYST FORMATION IN PIG

Extract from Xenopus eggs can induce reprogramming in somatic cells. In our previous study, cell colony formation was induced during culture of porcine fetal fibroblasts after a single treatment with Xenopus egg extract and culture for several passages and using these long-term cultured cells for cloning increased the resulting blastocyst rate (Liu et al. 2011 Reprod. Fertil. Dev. 23, 130). However, both colony number and cloned blastocyst rate decreased after Passage 15 and no colonies formed after Passage 18. Therefore, in this study we investigated the effect of a second extract treatment on colony formation and cloned blastocyst formation. Extract-treated (ExT) porcine fetal fibroblasts at Passage 13 (P13) grown on poly-L-lysine-coated coverslips were permeabilized by digitonin (7 μg mL–1, 2 min, 4°C) and incubated in extract at 37°C for 30 min. After resealing the membrane in DMEM supplemented with 2 mM CaCl2, the remaining cells were cultured in ES medium (Vejlsted et al. 2005 Mol. Reprod. Dev. 70, 445). The treated cells were split onto 2 coverslips on Day 7 after the second extract treatment (2ExT), defined as Passage 1 (2ExT P1, comparable with ExT P14). New subcultures were made every 7 to 8 days when 70 to 80% clusters became colonies (i.e. 2ExT P8). Colony cells from both ExT (P14 and P16) and 2ExT (P1, P3 and P6) were used for handmade cloning and nontreated cells were used as control (Day 0). Blastocyst rates were analysed by chi-square test and colony numbers were analysed by 1-way ANOVA (SAS version 9.2). Colony numbers and cloned blastocyst rates on Day 6 are summarised in Table 1. Colonies continued to form in treated cells from 2ExT P1 to P8. The colony number maintained at a high level (60 to 80) from 2ExT P4 to P8 and it was significantly higher than that of ExT cells at the comparable passage numbers. No colonies formed in control cells. When using 2ExT colony cells at P3 and P6 for cloning, the blastocyst rates increased compared with controls and they were also higher than in the ExT group. Cloned blastocyst rates were not different between 2ExT P1 and ExT P14 groups. In conclusion, a second extract treatment can induce colony formation and increase cloned blastocyst rates, indicating that this repeated extract treatment again could activate the extract-treated cells to an activity level similar to that achieved after the first treatment. Table 1.Summary of colony number and cloned blastocyst rate with ExT and 2ExT colony cells