A new integrable model of strongly correlated electrons with Hubbard-like interaction

A new completely integrable model of strongly correlated electrons is proposed which describes two competitive interactions: one is the correlated one-particle hopping, the other is the Hubbard-like interaction. The integrability follows from the fact that the Hamiltonian is derivable from a one-parameter family of commuting transfer matrices. The Bethe ansatz equations are derived by algebraic Bethe ansatz method.

Immunolocalization of the 38.3 kDa calponin-like protein in stratified muscles of the tail of Schistosoma japonicum cercariae

Calponins are proteins present in vertebrate smooth musculature where they occur in association with thin myofilaments. Calponins are not present in vertebrate or invertebrate striated muscles. The blood fluke Schistosoma japonicum expresses a 38.3-kDa protein that bears substantial homology with vertebrate calponin and occurs entirely within smooth musculature of adults. Calponin-like immunoreactivity has been demonstrated in smooth muscles of many invertebrate phyla. The Schistosoma japonicum calponin has been localised in smooth myofibrils of adults where it is associated with myofilaments and sarcoplasmic reticulum. In this study, the ultrastructural localisation of the protein in muscles of S. japonicum cercariae is described. The protein is present in smooth muscles of the forebody and the stratified muscle of the tail. Within the stratified layer, the protein occurs predominantly in transverse arrays of sarcoplasmic reticulum. The localisation data suggest that the calponin-like protein of S. japonicum is involved in contraction of the stratified tail muscle. Furthermore, the presence of a calponin system in the stratified muscle suggests that this muscle is simply a superior form of muscle, closely related to smooth muscles that use a caldesmin-calponin system in contraction. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

Cytotoxic Effects of Different Concentrations of a Carbamide Peroxide Bleaching Gel on Odontoblast-Like Cells MDPC-23

This study evaluated the cytotoxic effects of a carbamide peroxide (CP) bleaching gel at different concentrations on odontoblast-like cells. Immortalized cells of the MDPC-23 cell line (30,000 cells/cm(2)) were incubated for 48 h. The bleaching gel was diluted in DMEM culture medium originating extracts with different CP concentrations. The amount (mu g/mL) of hydrogen peroxide (H(2)O(2)) released from each extract was measured by the leukocrystal violet/horseradish peroxidase enzyme assay. Five groups (n = 10) were formed according to the CP concentration in the extracts: G1-DMEM (control); G2-0.0001 % CP (0.025 mu g/mL H(2)O(2)); G3-0.001% CP (0.43 mu g/mL H(2)O(2)); G4-0.01% CP (2.21 mu g/mL H(2)O(2)); and G5-0.1 % CP (29.74 mu g/mL H(2)O(2)). MDPC-23 cells were exposed to the bleaching gel extracts for 60 min and cell metabolism was evaluated by the NITT assay. Data were analyzed statistically by one-way ANOVA and Tukey`s test (alpha = 0.05). Cell morphology was examined by scanning electron microscopy. The percentages of viable cells were as follows: G1, 100%; G2, 89.41%; G3, 82.4%; G4, 61.5%; and G5, 23.0%. G2 and G3 did not differ significantly (p > 0.05) from G1. The most severe cytotoxic effects were observed in G3 and G4. In conclusion, even at low concentrations, the CP gel extracts presented cytotoxic effects. This cytotoxicity was dose-dependent, and the 0.1% CP concentration caused the most intense cytopathic effects to the MDPC-23 cells. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 9013: 907-912, 2009

Insulin-like growth factor 2 cDNA cloning and ontogeny of gene expression in the liver of the marsupial brushtail possum (Trichosurus vulpecula)

The cDNA sequence for insulin-like growth factor 2 (IGF-2) was determined from the liver of the marsupial brushtail possum (Trichosurus vulpecula) using reverse transcription followed by polymerase chain reaction (RT-PCR) with gene-specific primers. The 359 bp of possum sequence encompassed the mature peptide, 27 bp of the signal peptide, and 125 bp of the E-peptide. Alignment of the deduced amino acid sequence with those from other species indicated that the mature peptide was 71 amino acids in length, 4 amino acids longer than most other mammals. At both the nucleotide and amino acid levels there was a high degree of sequence identity with IGF-2 from other mammalian and nonmammalian species. Amino acid identity ranged from 94.4% with a variant form of human IGF-2 to 80.3% with zebrafinch IGF-2. Northern analysis revealed that radiolabeled possum IGF-2, cDNA hybridized to multiple transcripts in the liver of both adult possums and 150-day-old pouch young and that the overall level of expression was greater in pouch young. Semiquantitative RT-PCR with total RNA from liver samples of pouch young aged 12 to 150 days postpartum and adults confirmed that IGF-2 gene expression was two to three times more abundant in pouch young than in adults but there was no significant change in the level of expression during pouch life. Unlike other mammalian species, in which there is a decline in levels of liver IGF-2 gene expression around the time of birth, levels in the marsupial brushtail possum remain elevated for at least 150 days after birth. This suggests that the decline in liver IGF-2 expression in marsupials and eutherians occurs at a similar stage of development and may reflect a role for this growth factor during the postnatal growth and development of the marsupial, (C) 2001 Academic Press.

Relating body mass index to figural stimuli: population-based normative data for Caucasians

OBJECTIVE: To establish body mass index (BMI) norms for standard figural stimuli using a large Caucasian population-based sample. In addition, we sought to determine the effectiveness of the figural stimuli to identify individuals as obese or thin. DESIGN: All Caucasian twins born in Virginia between 1915 and 1971 were identified by public birth record. In addition, 3347 individual twins responded to a letter published in the newsletter of the American Association of Retired Persons (AARP). All adult twins (aged 18 and over) from both of these sources and their family members were mailed a 16 page 'Health and Lifestyle' questionnaire. SUBJECTS: BMI and silhouette data were available on 16 728 females and 11 366 males ranging in age from 18- 100. MEASUREMENTS: Self-report information on height-weight, current body size, desired body size and a discrepancy score using standard figural stimuli. RESULTS: Gender- and age-specific norms are presented linking BMI to each of the figural stimuli. Additional norms for desired body size and discrepancy scores are also presented. Receiver operating curves (ROC) indicate that the figural stimuli are effective in classifying individuals as obese or thin. CONCLUSIONS: With the establishment of these norms, the silhouettes used in standard body image assessment can now be linked to BMI. Differences were observed between women and men in terms of desired body size and discrepancy scores, with women preferring smaller sizes. The figural stimuli are a robust technique for classifying individuals as obese or thin.

Extracting ontological concepts for tendering conceptual structures

It has been argued that beyond software engineering and process engineering, ontological engineering is the third capability needed if successful e-commerce is to be realized. In our experience of building an ontological-based tendering system, we face the problem of building an ontology. In this paper, we demonstrate how to build ontologies in the tendering domain. The ontology life cycle is identified. Extracting concepts from existing resources like on-line catalogs is described. We have reused electronic data interchange (EDI) to build conceptual structures in the tendering domain. An algorithm to extract abstract ontological concepts from these structures is proposed.

Blink startle modulation during anticipation of pleasant and unpleasant stimuli

The present research investigated blink startle modulation during the anticipation of pleasant, unpleasant, or neutral pictures. In Experiment 1 (N = 18), participants were presented with three different tone-picture pairings. Tones differed in pitch and were followed by pleasant, neutral or unpleasant pictures. Acoustic blink reflexes were elicited during some tones and during stimulus free intervals. Blink facilitation during tones that preceded pleasant and unpleasant pictures was larger than during the tone that preceded neutral pictures. Experiment 2 (N = 10) assessed whether this difference was due to a difference in the presentation frequency of the three conditions. No difference in blink facilitation between the conditions was found when pictures of flowers and mushrooms replaced the pleasant and unpleasant pictures, indicating that picture content was instrumental in causing the differential blink facilitation in Experiment 1. The results from Experiment 1 seem to indicate that startle modulation during the anticipation of pictorial material reflects the interest in or the arousal associated with the pictures rather than picture valence.

Human papillomavirus type 6b virus-like particles are able to activate the Ras-MAP kinase pathway and induce cell proliferation

The initial step in viral infection is the attachment of the virus to the host cell via an interaction with its receptor. We have previously shown that a receptor for human papillomavirus is the alpha6 integrin. The alpha6 integrin is involved in the attachment of epithelial cells with the basement membrane, but recent evidence suggests that ligation of many integrins results in intracellular signaling events that influence cell proliferation. sere we present evidence that exposure of A431 human epithelial cells to human papillomavirus type 6b L1 virus-like particles (VLPs) results in a dose-dependent increase in cell proliferation, as measured by bromodeoxyuridine incorporation. This proliferation is Lost if VLPs are first denatured or incubated with a monoclonal antibody against L1 protein. The MEK1 inhibitor PB98059 inhibits the VLP-mediated increase in fell proliferation, suggesting involvement of the Ras-MAP kinase pathway, Indeed, VLP binding results in rapid phosphorylation of the beta4 integrin upon tyrosine residues and subsequent recruitment of the adapter protein She to beta4, Within 30 min, the activation of Ras, Raf, and Erk2 was observed. Finally, the upregulation of c-myc mRNA was observed at 60 min, These data indicate that human papillomavirus type 6b is able to signal cells via the Ras-MAP kinase pathway to induce cell proliferation. We hypothesize that such a mechanism would allow papillomaviruses to infect hosts more successfully by increasing the potential pool of cells they are able to infect via the initiation of proliferation in resting keratinocyte stem and suprabasal cells.

The changing face of ciguatera

Ciguatera is a global disease caused by the consumption of certain warm-water fish (ciguateric fish) that have accumulated orally effective levels of sodium channel activator toxins (ciguatoxins) through the marine food chain. Symptoms of ciguatera include a range of gastrointestinal, neurological and cardiovascular disturbances. This review examines progress in our understanding of ciguatera from the work of Banner in the late 1950s to the present. Similarities and differences in ciguatera in the Pacific Ocean, Indian Ocean and Caribbean Sea are highlighted, and future research directions are suggested. (C) 2000 Elsevier Science Ltd. All rights reserved.

Development and characterisation of recombinant hepatitis delta virus-like particles

Injection of particulate hepatitis B virus surface antigen (HBsAg) in mice leads to the induction of a HBsAg-specific class-I-restricted cytotoxic T lymphocyte (CTL) response. It is proposed that any protein internal to HBsAg will also be able to elicit a specific CTL response. In this study, several carboxy-terminal truncations of hepatitis C virus (HCV) core protein were fused to varying lengths of amino-terminal truncated large hepatitis delta antigen (L-HDAg). These constructs were analysed for their ability to be expressed and the particles secreted in the presence of HBsAg after transfection into HuH-7 cells. The secretion efficiency of the various HCV core-HDAg chimeric proteins was generally poor. Constructs containing full length HDAg appeared to be more stable than truncated versions and the length of the inserted protein was restricted to around 40 amino acids. Thus, the use of L-HDAg as a chimera to package foreign proteins is limited. Consequently, a polyepitope (polytope) containing a B-cell epitope from human papillomavirus (HPV 16) and multiple T-cell epitopes from the HCV polyprotein was used to create the construct, L-HDAg-polyB. This chimeric protein was shown to be reliant on the co-expression of HBsAg for secretion into the cell culture fluid and was secreted more efficiently than the previous HCV core-HDAg constructs. These L-HDAg-polyB virus-like particles (VLPs) had a buoyant density of similar to 1.2 g/cm(3) in caesium chloride and similar to 1.15 g/cm(3) in sucrose. The VLPs were also immunoprecipitated using an anti-HBs but not an anti-HD antibody. Thus, these recombinant VLPs have similar biophysical properties to L-HDAg VLPs.

Adsorption study of benzene in ink-bottle-like MCM-41

The pore-opening size of MCM-41 is tailored to be in the microporous region using a chemical vapor deposition technique for selective tailoring. Although the pore opening is narrowed, the internal pore body of MCM-41 remains unchanged so the pore volume retains a substantial portion (80%) of its original value. The adsorption equilibrium of nitrogen and benzene in the modified MCM-41 shows a type I isotherm, which significantly improves the adsorption performance of MCM-41 for low-concentration volatile organic compounds. The adsorption kinetics of benzene in the modified MCM-41 is also studied.

Major colour patterns of reef-building corals are due to a family of GFP-like proteins

Reef-building corals are renowned for their brilliant colours yet the biochemical basis for the pigmentation of corals is unknown. Here, we show that these colours are due to a family of GFP-like proteins that fluoresce under ultraviolet (UV) or visible light. Pigments from ten coral species were almost identical to pocilloporin (Dove et al. 1995) being dimers or trimers with approximately 28-kDa subunits. Degenerative primers made to common N-terminal sequences yielded a complete sequence from reef-building coral cDNA, which had 19.6% amino acid identity with green fluorescent protein (GFP). Molecular modelling revealed a 'beta -can' structure, like GFP, with 11 beta -strands and a completely solvent-inaccessible fluorophore composed of the modified residues Gln-61, Tyr-62 and Gly-63. The molecular properties of pocilloporins indicate a range of functions from the conversion of high-intensity UV radiation into photosynthetically active radiation (PAR) that can be regulated by the dinoflagellate peridinin-chlorophyll-protein (PCP) complex, to the shielding of the Soret and Q(x) bands of chlorophyll a and c from scattered high-intensity light. These properties of pocilloporin support its potential role in protecting the photosynthetic machinery of the symbiotic dinoflagellates of corals under high light conditions and in enhancing the availability of photosynthetic light under shade conditions.