Role of lateral and feedback connections in primary visual cortex in the processing of spatiotemporal regularity - a TMS study

Our human visual system exploits spatiotemporal regularity to interpret incoming visual signals. With a dynamic stimulus sequence of four collinear bars (predictors) appearing consecutively toward the fovea, followed by a target bar with varying contrasts, we have previously found that this predictable spatiotemporal stimulus structure enhances target detection performance and its underlying neural process starts in the primary visual cortex (area V1). However, the relative contribution of V1 lateral and feedback connections in the processing of spatiotemporal regularity remains unclear. In this study we measured human contrast detection of a briefly presented foveal target that was embedded in a dynamic collinear predictor-target sequence. Transcranial magnetic stimulation (TMS) was used to selectively disrupt V1 horizontal and feedback connections in the processing of predictors. The coil was positioned over a cortical location corresponding to the location of the last predictor prior to target onset. Single-pulse TMS at an intensity of 10% below phosphene thresholdwas delivered at 20 or 90ms after the predictor onset. Our analysis revealed that the delivery of TMS at both time windows equally reduced, but did not abolish, the facilitation effect of the predictors on target detection. Furthermore, if the predictors' ordination was randomized to suppress V1 lateral connections, the TMS disruption was significantly more evident at 20ms than at 90-ms time window. We suggest that both lateral and feedback connections contribute to the encoding of spatiotemporal regularity in V1. These findings develop understanding of how our visual system exploits spatiotemporal regularity to facilitate the efficiency of visual perception.

Identification of human-selective analogues of the vascular-disrupting agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA)

Background:

Species selectivity of DMXAA (5,6-dimethylxanthenone-4-acetic acid, Vadimezan) for murine cells over human cells could explain in part the recent disappointing phase III trials clinical results when preclinical studies were so promising. To identify analogues with greater human clinical potential, we compared the activity of xanthenone-4-acetic acid (XAA) analogues in murine or human cellular models.

Methods:

Analogues with a methyl group systematically substituted at different positions of the XAA backbone were evaluated for cytokine induction in cultured murine or human leukocytes; and for anti-vascular effects on endothelial cells on matrigel. In vivo antitumour activity and cytokine production by stromal or cancer cells was measured in human A375 and HCT116 xenografts.

Results:

Mono-methyl XAA analogues with substitutions at the seventh and eighth positions were the most active in stimulating human leukocytes to produce IL-6 and IL-8; and for inhibition of tube formation by ECV304 human endothelial-like cells, while 5- and 6-substituted analogues were the most active in murine cell systems.

Conclusion:

Xanthenone-4-acetic acid analogues exhibit extreme species selectivity. Analogues that are the most active in human systems are inactive in murine models, highlighting the need for the use of appropriate in vivo animal models in selecting clinical candidates for this class of compounds.

Short communication: evaluation of Brucella infection of cows by PCR detection of Brucella DNA in raw milk

The collection of serum samples from cows is frequently difficult to implement in large-scale surveys, and may involve a high risk of occupational infection. This study assessed the potential of using raw milk sampling as a suitable method for use in a pilot survey of Brucella abortus infection status in cattle. Raw milk samples from 816 cows were examined. Polymerase chain reaction assays of raw milk, with primers derived from the IS711 element of the Brucella genome, were used. Of the cows, 55 were Brucella positive based on serum agglutination test (SAT) results. Polymerase chain reaction amplified Brucella DNA in 25 (45%) of the 55 SAT-positive cows. All of the 689 SAT-negative cows were found to be negative in PCR assays of their milk. Brucella infection status based on PCR results was then predicted for 72 cows from private h erds in which the brucellosis status was unknown. Subsequently, SAT verification of Brucella status was performed. There was no significant difference between predicted and actual SAT-positive rates in those 72 cows. This study indicates a relationship between Brucella detection levels obtained using milk-based PCR results and SAT results. The specific, rapid, and easy sampling procedure within milk-based PCR assaying for brucellosis detection makes the milk PCR method an attractive alternative for evaluation of B. abortus infection in cows, particularly if used as a routine screening and surveillance tool to reduce brucellosis outbreaks.

Xanthones from mangosteen extracts as natural chemopreventive agents: potential anticancer drugs

Despite decades of research, the treatment and management of malignant tumors still remain a formidable challenge for public health. New strategies for cancer treatment are being developed, and one of the most promising treatment strategies involves the application of chemopreventive agents. The search for novel and effective cancer chemopreventive agents has led to the identification of various naturally occurring compounds. Xanthones, from the pericarp, whole fruit, heartwood, and leaf of mangosteen (Garcinia mangostana Linn., GML), are known to possess a wide spectrum of pharmacologic properties, including antioxidant, anti- tumor, anti-allergic, anti-inflammatory, anti-bacterial, anti-fungal, and anti-viral activities. The potential chemopreventive and chemotherapeutic activities of xanthones have been demonstrated in different stages of carcinogenesis (initiation, promotion, and progression) and are known to control cell division and growth, apoptosis, inflammation, and metastasis. Multiple lines of evidence from numerous in vitro and in vivo studies have confirmed that xanthones inhibit proliferation of a wide range of human tumor cell types by modulating various targets and signaling transduction pathways. Here we provide a concise and comprehensive review of preclinical data and assess the observed anticancer effects of xanthones, supporting its remarkable potential as an anticancer agent.

Unusual thermoelectric behavior indicating a hopping to bandlike transport transition in pentacene

An unusual increase in the Seebeck coefficient with increasing charge carrier density is observed in pentacene thin film transistors. This behavior is interpreted as being due to a transition from hopping transport in static localized states to bandlike transport, occurring at temperatures below ∼250  K. Such a transition can be expected for organic materials in which both static energetic disorder and dynamic positional disorder are important. While clearly visible in the temperature and density dependent Seebeck coefficient, the transition hardly shows up in the charge carrier mobility.

First Report of the Stubby Root Nematode, Paratrichodorus minor, in Mainland China

The stubby root nematode, Paratrichodorus minor (Colbran, 1956) Siddiqi, 1974, is an economically important species. It not only causes direct damage to the meristemic tissues of plants, but also can be a vector of Tobacco rattle virus and Pepper ringspot virus (2). It has been documented in Afghanistan, Argentina, Australia, Brazil, Canary Islands, Cuba, Egypt, Fiji, India, Israel, Ivory Coast, Japan, Java, Mauritania, New Zealand, Nicaragua, Philippines, Puerto Rico, Senegal, South Africa, Taiwan, Upper Volta, the United States, the former USSR, and Venezuela (1). During a recent investigation on Trichodoridae occurring in China, eight stubby root nematode populations were detected in Hainan, Yunnan, and Fujian provinces in the rhizospheres of eggplant (Solanum melongena), Chinaberry (Melia azedarach), lettuce (Lactuca sativa), longan (Dimocarpus longan), peach (Prunus persica), pear (Pyrus sp.), and walnut (Juglans regia) in soils ranging from clay to sand. The eight populations had similar morphological and molecular characters. The females were cigar shaped with rod-shaped vaginal sclerotization parallel to the longitudinal body axis with a quadrangular vagina in side view having a short vulval slit. The key morphometrics of females were consistent with those of P. minor: body length, 631 to 757 μm; body diameter, 27 to 43 μm; onchiostyle, 35 to 36 μm; a, 18 to 24; b, 4.9 to 5.5; v%, 53 to 55; length of vagina, 10.8 to 11.1 μm; and size of vaginal pieces, 1.7 to 1.9 μm. Males in P. minor are rare and were not found in any of the eight populations. Partial sequences of the 18s RNA gene of each population were amplified with forward primer 5'-AAA GAT TAA GCC ATG CAT G-3' (2), and reverse primer 5'-AGT CAA ATT AAG CCG CAG-3' (3), which yielded a PCR fragment of 1,153 bp. PCR products from all eight populations were sequenced and submitted to GenBank and assigned Accession Nos. GQ995703, GQ995704, GQ995705, GQ995706, GQ995707, GQ995708, GQ995709, and GQ995710. The sequences exhibited 99.8 to 100% similarity with those of P. minor isolates DQ345526, AM269897, AJ438052, AJ438053, and AJ438058 from GenBank. Morphological and molecular identification confirmed that all populations were P. minor. To our knowledge, this is the first report of P. minor in mainland China. References: (1) K. Boutsika et al. Nematology 6:145, 2004. (2) W. Decramer. The Family Trichodiridae: Stubby Root and Virus Vector Nematodes. Kluwer Academic Publishers, Dordrecht, the Netherlands, 1995. (3) I. S. Waite et al. Soil Biol. Biochem. 35:1165, 2003.

Evaluation of field and laboratory protocols used to detect avian influenza viruses in wild aquatic birds

Careful selection and observance of standard field and laboratory protocols are critical for successful detection and characterization of avian influenza viruses (AIV) from wild birds. Cloacal swabs were collected from hunter-killed or nesting waterfowl and shorebirds from wildlife refuges in Alabama, Georgia, and Florida during 2006 to 2008. Swab samples were inoculated into embryonated eggs followed by hemagglutination (HA) test to determine the presence of hemagglutinating agents. Antigen capture-ELISA (AC-ELISA) and real-time reverse transcription-PCR (RRT-PCR) were used to detect AIV from both allantoic fluids (AF) and swab specimens of HA-positive samples. Hemagglutination inhibition test was used to detect Newcastle disease virus, another hemagglutinating virus common in wild birds. The HA-positive AF were sent to the National Veterinary Services Laboratory for subtyping of the isolates. Out of 825 samples tested, 19 AIV and 3 avian paramyxovirus subtypes were identified by the National Veterinary Services Laboratory. Without egg passage, AC-ELISA did not detect virus, whereas matrix gene of 13 AIV were detected using RRT-PCR. When testing was done on AF, 14 were positive for influenza A by AC-ELISA and 20 by RRT-PCR. Antigen capture-ELISA did not detect influenza A when the HA titer was lower than 125, whereas RRT-PCR detected AIV from AF with HA titer as low as 4. The highest isolation rate was from Florida, where out of 109 samples analyzed, 14 AIV were detected by RRT-PCR from AF. Real-time reverse transcription-PCR was more sensitive, specific, and cost-effective than AC-ELISA. However, to avoid false-negative results, testing should be performed on AF and not directly from cloacal swabs. Our procedures to detect AIV directly from cloacal swabs need further optimization for improved sensitivity.

Safety, reactogenicity and immunogenicity of Francisella tularensis live vaccine strain in humans

We evaluated the safety, reactogenicity and immunogenicity of escalating doses of a new Francisella tularensis Live Vaccine Strain (LVS) lot by scarification (SCAR) or subcutaneously (SQ) in humans. Subjects (N=10/group) received one dose of LVS via SCAR at 10(5),10(7) or 10(9)cfu/ml or SQ at 10(2), 10(3),10(4) or 10(5)cfu/ml; 14 subjects received placebo. All doses/routes were well tolerated. When compared to placebo, vaccination with 10(7) SCAR and 10(9) SCAR resulted in significantly higher serologic response frequencies, as measured by ELISA for IgG, IgM, IgA and microagglutination; whereas vaccination with 10(5) SCAR, 10(7) SCAR 10(9) SCAR and 10(5) SQ elicited a significantly higher interferon-gamma response frequency.

Detection and characterization of avian influenza and other avian paramyxoviruses from wild waterfowl in parts of the southeastern United States

Cloacal swabs were taken from migratory hunter-killed, nonmigratory, nesting waterfowl and migratory shorebirds from wildlife refuges in Alabama, Georgia, and Florida during 2006 to 2008. Samples were processed in embryonated eggs followed by hemagglutination (HA), Directigen, and real-time reverse transcription-PCR tests. Sequence analysis of the hemagglutinin (H) gene of the H10N7 Alabama isolate revealed that it was closely related (98%) to recent isolates from Delaware and Canada, but only 90% related to an H10N7 isolated 30 yr ago. Four isolates had 94 to 97% similarity to published H1N1 isolates including one from swine. No H5 or H7 isolates were found. One sample was highly pathogenic in embryos, produced a high HA titer, and was positive for both avian influenza (AIV) and Newcastle disease virus or avian paramyxovirus (APMV)-1. In recent (2008) sampling, more (14%) AIV, APMV, or both were isolated than in 2006 to 2007 (1% isolation rate). The higher isolation rate during 2008 may be attributed to optimized sample collection, storage in dry ice, new egg incubator, healthier eggs, time or habitat for isolation, species sampled, migratory status of birds, and more experience with detection procedures. An additional egg passage resulted in increased viral titer; however, no HA-negative samples became HA positive. The chance of transmission of APMV or low-nonpathogenic AIV from wild waterfowl to commercial poultry is possible. However, the chance of transmission of H5 or H7 AIV isolates from waterfowl to commercial farms in Alabama, Georgia, or Florida is unlikely. Therefore, continual testing of these birds is justified to ensure that H5 or H7 AIV are not transmitted to commercial poultry.

Genetic deletion of faim reveals its role in modulating c-FLIP expression during CD95-mediated apoptosis of lymphocytes and hepatocytes

Fas-apoptosis inhibitory molecule (FAIM) is inducibly expressed in B lymphocytes and had been shown to antagonize Fas-mediated killing of B-cell lines in vitro. However, its mechanism and role in vivo are unknown. We have generated faim(-/-) mice and found these mutants to be viable. In contrast to fas(-/-) mice, faim(-/-) mice have normal B- and T-cell populations. However, faim(-/-) B cells and thymocytes show increased sensitivity to Fas-triggered apoptosis in vitro, and faim(-/-) mice suffer greater mortality and exhibit exacerbated liver damage in response to Fas (CD95) engagement in vivo. The lack of FAIM results in greater activation of caspase-8 and -3 in Fas-stimulated thymocytes. Detailed biochemical analyses further reveal the decreased expression of c-FLIP(L) and c-FLIP(R) in faim(-/-) thymocytes and increased association of caspase-8 with Fas in Fas-activated mutant cells. Decreased levels of c-FLIP(L) and c-FLIP(R) are also evident in faim(-/-) liver. Thus, FAIM plays a novel role in modulating Fas-mediated apoptosis and acts through influencing the expression of c-FLIP and regulating the physical binding of caspase-8 to Fas.

Effects of a natural extract of chestnut wood on digestibility, performance traits, and nitrogen balance of broiler chicks

Currently, feed ingredients containing tannin are attracting more interest as substitutes for antibiotic growth promoters in animal and poultry feeding. This study investigated the influence of a natural extract of chestnut wood (Silvafeed ENC) on broiler digestibility (experiment 1) and on the growth performance, carcass quality, and nitrogen balance of broilers (experiment 2). Results showed that the inclusion of ENC did not influence the apparent digestibility of organic matter, CP, and ether extract. Chick growth performance showed a quadratic or cubic response with increasing levels of ENC. When chicks were fed ENC from 14 to 56 d of age, the ENC had a positive effect on average daily gain in the first 2 wk of addition, whereas this effect was not evident in the last 2 wk compared with the control group. Similar trends were also shown for daily feed intake. Overall, the chicks fed 0.20% ENC had significantly better growth performance than the control group. Carcass analysis showed no gross lesions in organs and no significant differences in thigh and breast composition among groups. Noteworthy is the fact that the ENC-treated groups had less total litter nitrogen; in particular, chicks fed 0.15 and 0.20% ENC showed a significant difference in total litter nitrogen compared with the control group. No significant difference in nitrogen balance was observed. Addition of 0.20% ENC seemed to have a positive influence on chick feeding.

Activation of granulocytes by direct interaction with dendritic cells

Granulocytes from human peripheral blood were co-cultured with conventional dendritic cells (cDC) or plasmacytoid DCs (pDC) to examine the effects of DCs on the activation or function of granulocytes. After co-culture of granulocytes with DCs, expression of the activation markers of granulocytes (CD63 and CD64) was up-regulated, and increased expression of CD50, the activation marker and ligand for CD209 (DC-SIGN) was also observed. The interaction of granulocytes with DCs was visualized as the cluster where DCs, especially cDCs, were surrounded by granulocytes to form a 'rosette'. After co-culture of granulocytes with cDCs, the secretion of elastase from granulocytes was enhanced significantly when examined cytohistochemically and by enzyme-linked immunosorbent assay. An increase in myeloperoxidase (another activation index of granulocytes) was also observed after co-culture with DCs. These findings suggest the functional and phenotypical activation of granulocytes by interaction with DCs. Furthermore, we examined the involvement of adhesion molecules in the granulocyte-DC interaction, and found that CD209 participates to some extent in this interaction.

Aptamer-based isolation and subsequent imaging of mesenchymal stem cells in ischemic myocard by magnetic resonance imaging

PURPOSE

Mesenchymal stem cells (MSC) seem to be a promising cell source for cellular cardiomyoplasty. We recently developed a new aptamer-based specific selection of MSC to provide "ready to transplant" cells directly after isolation. We evaluated MRI tracking of newly isolated and freshly transplanted MSC in the heart using one short ex vivo selection step combining specific aptamer-based isolation and labeling of the cells.

MATERIALS AND METHODS

Bone marrow (BM) was collected from healthy pigs. The animals were euthanized and the heart was placed in a perfusion model. During cold ischemia, immunomagnetic isolation of MSC from the BM by MSC-specific aptamers labeled with Dynabeads was performed within 2 h. For histological identification the cells were additionally stained with PKH26. Approx. 3 x 10(6) of the freshly aptamer-isolated cells were injected into the ramus interventricularis anterior (RIVA) and 5 x 10(5) cells were injected directly into myocardial tissue after damaging the respective area by freezing (cryo-scar). 3 x 10(6) of the aptamer-isolated cells were kept for further characterization (FACS and differentiation assays). 20 h after cell transplantation, MRI of the heart using a clinical 3.0 Tesla whole body scanner (Magnetom Trio, Siemens, Germany) was performed followed by histological examinations.

RESULTS

The average yield of sorted cells from 120 ml BM was 7 x 10(6) cells. The cells were cultured and showed MSC-like properties. MRI showed reproducible artifacts within the RIVA-perfusion area and the cryo-scar with surprisingly excellent quality. The histological examination of the biopsies showed PKH26-positive cells within the areas which were positive in the MRI in contrast to the control biopsies.

CONCLUSION

Immunomagnetic separation of MSC by specific aptamers linked to magnetic particles is feasible, effective and combines a specific separation and labeling technique to a "one stop shop" strategy.

Molecular and phenotypic characterization of infectious bursal disease virus isolates

Two infectious bursal disease viruses (IBDVs 1174 and V1) were isolated from IBDV-vaccinated broiler flocks in California and Georgia. These flocks had a history of subclinical immunosuppression. These isolates are commonly used in IBDV progeny challenge studies at Auburn, AL, as well as vaccine manufacturer's vaccine efficacy studies, because they come from populated poultry-producing states, and are requested by poultry veterinarians from those states. Nested polymerase chain reaction (PCR) generated viral genome products for sequencing. A 491-bp segment from the VP2 gene, covering the hypervariable region, from each isolate was analyzed and compared with previously sequenced isolates. Sequence analysis showed that they were more closely related to the Delaware (Del) E antigenic variant than they are to the Animal Health Plant Inspection Service (APHIS) standard, both at the nucleotide level (96%, 97%) and at the amino acid level (94%, 97%). Both isolates had the glutamine to lysine shift in amino acid 249 which has been reported to be critical in binding the virus neutralizing Mab B69. Phenotypic studies showed that both isolates produced rapid atrophy of the bursae and weight loss, without the edematous bursal phase, in 2-wk-old commercial broilers having antibody against IBDV. A progeny challenge study showed both isolates produced more atrophy of the bursae (less percentage of protection) than the Del E isolate. Molecular and phenotypic data of these important IBDV isolates help in the improved detection and control of this continually changing and important viral pathogen of chickens.

Upregulation of frizzled 9 in astrocytomas

Wnt/frizzled (FZD) cascades play important roles in controlling cell fate, proliferation, migration, tissue architecture and organogenesis during embryonic development and in adult organisms. The potential involvement of this pathway in tumorigenesis has been established in several types of cancers. Frizzled 9 (FZD9) is expressed in brain and its aberrant expression in gastric cancer was observed. However, its association with astrocytomas remains unknown therefore we studied FZD9 expression in astrocytomas of different malignancy. In the present study, FZD9 expression in 25 astrocytomas was investigated using immunohistochemistry with specific antibodies. Further FZD9 expression in native human brain tissue and glioblastoma cell line were analysed using real-time reverse transcription polymerase chain reaction (RT-PCR). In human astrocytomas, FZD9 immunoreactivity (IR) was observed in both microvessels and neoplastic cells. The percentage of FZD9+ microvessels in relation to FZD9+ vessels was significantly higher in malignant astrocytomas than in low-grade astrocytomas and positively correlated with the astrocytoma World Health Organization (WHO) grading (r = 1, P = 0.04). Furthermore, the FZD9 IR scores positively correlated with astrocytoma WHO grading (r = 1, P = 0.04) and proliferating activity (r = 0.77, P < 0.001). Real-time RT-PCR data showed that FZD9 expression in human glioblastoma was significant higher than in normal brain (P < 0.05) but FZD9 expression was only slightly induced in cobalt chloride-treated human glioblastoma T98G cells compared with untreated cells (P > 0.05). FZD9 is upregulated in astrocytomas, suggesting that FZD9 could be important in the tumorigenesis of human astrocytomas.