bluuebunny/crossref_metadata_2025 huggingface dataset:
DNA‐Directed Attachment of Carbon Nanotubes for Enhanced Label‐Free Electrochemical Detection of DNA Hybridization
Authors: Kerman Kagan , Morita Yasutaka , Takamura Yuzuru , Ozsoz Mehmet , Tamiya Eiichi
Published: September 2004

Multi‐walled carbon nanotubes (MWNTs) were used as nanowires, which combined DNA molecules to a carbon paste electrode (CPE). The attachment of MWNT on the electrode surface was controlled by a hybridization assay between adenine and thymine containing oligonucleotides. The appearance of guanine oxidation signal after hybridization with target DNA greatly simplified the specific sequence DNA detection mechanism. Combination of sidewall‐ and end‐functionalization of MWNT provided a significant enhancement in the voltammetric signal of guanine oxidation in comparison with the signals obtained from only end‐oxidized MWNT modified CPE and a bare CPE. A control experiment involving adenine containing polynucleotide (poly(A)) instead of adenine probe modified MWNT was performed. The effect of target and noncomplementary DNA concentration on the guanine signal was also monitored. Discrimination against single‐base mismatch and noncomplementary DNA was achieved by surfactant containing washing solution. The promising conductivity of carbon nanotubes, and the creation of a larger surface area for DNA immobilization by sidewall‐ and end‐oxidation of MWNT provided a detection limit down to 10 pg/mL, which is compatible with the demand of the genetic tests.
SNPs Feasibility of Nonlabeled Oligonucletides on Using Electrochemical Sensing
Authors: Lee Hea Yeon , Park Jong Wan , Kawai Tomoji
Published: September 2004

We have demonstrated an electrochemical gene chip protocol for the SNPs detection of nonlabeled DNA. Using an array consisting of streptavidin‐modified gold electrodes, probe DNA were attached through the application of a direct electric field. Electrochemical response changes originating from the hybridization of nucleic acids to protein‐bound nucleic acids using soluble mediators in K3Fe(CN)6 solution could then be observed. The electrochemical protocol developed showed high sensitivity and good reproducibility in the detection of DNA hybridization. Significant changes in electrochemical signals were also observed when using target DNA with a single base mismatch, indicating the applicability of this method to single nucleotide polymorphisms (SNPs) detection.
Highly Sensitive Amperometric Glucose Biosensor Based on Glassy Carbon Electrode with Copper/Palladium Coating
Authors: Dai Yi‐Qing , Shiu Kwok‐Keung
Published: September 2004

A highly sensitive amperometric glucose biosensor based on immobilizing glucose oxidase in electropolymerized poly(o‐phenylenediamine) film on glassy carbon electrode coated sequentially with copper and palladium layers has been developed. The steady‐state amperometric response to glucose was determined by means of the oxidation of hydrogen peroxide generated by the enzymatic reaction at a potential of either +0.70 or +0.40 V (vs. Ag|AgCl reference). The deposited copper/palladium layer showed great enhancement in the performance of the enzyme electrode, possibly due to its better electrocatalytic activity for hydrogen peroxide oxidation and large surface area. Effects of the relative loading of palladium, enzyme and polymer on the electrode performance were examined in detail. Sensitivity and detection limit for glucose determinations at +0.70 V were about 7.3 μA/mM and 0.1 μM, respectively. A wide linear range up to 6.0 mM glucose could be achieved. Electrode performance was superior to similar works reported in the literature. The response time was less than 2 s and its lifetime was longer than three months. The permeable polyphenylenediamine film also offered good anti‐interference ability to ascorbic acid, uric acid and acetaminophen, especially when a detection potential of +0.40 V was employed.
Carbon Nanotubes‐Based Amperometric Cholesterol Biosensor Fabricated Through Layer‐by‐Layer Technique
Authors: Guo Manli , Chen Jinhua , Li Jia , Nie Lihua , Yao Shouzhuo
Published: September 2004

A carbon nanotubes‐based amperometric cholesterol biosensor has been fabricated through layer‐by‐layer (LBL) deposition of a cationic polyelectrolyte (PDDA, poly(diallyldimethylammonium chloride)) and cholesterol oxidase (ChOx) on multi‐walled carbon nanotubes (MWNTs)‐modified gold electrode, followed by electrochemical generation of a nonconducting poly(o‐phenylenediamine) (PPD) film as the protective coating. Electrochemical impedance measurements have shown that PDDA/ChOx multilayer film could be formed uniformly on MWNTs‐modified gold electrode. Due to the strong electrocatalytic properties of MWNTs toward H2O2 and the low permeability of PPD film for electroacitve species, such as ascorbic acid, uric acid and acetaminophen, the biosensor has shown high sensitivity and good anti‐interferent ability in the detection of cholesterol. The effect of the pH value of the detection solution on the response of the biosensor was also investigated. A linear range up to 6.0 mM has been observed for the biosensor with a detection limit of 0.2 mM. The apparent Michaelis‐Menten constant and the maximum response current density were calculated to be 7.17 mM and 7.32 μA cm−2, respectively.
Chemically Sensitive Field‐Effect Transistors and Chemiresistors: New Materials and Device Structures
Authors: Katz Howard E.
Published: September 2004

Electronic sensor technology remains of widespread and intense interest. There are compelling needs to detect chemical species ranging from small molecules dispersed in the gas phase to complex biopolymers in aqueous solution. This review describes some recent advances in three main areas: chemically sensitive resistors (chemiresistors, CRs) including inorganic and organic based devices, field effect transistors (FETs) with semiconducting layers and/or gates with chemical sensitivity, and sensors based on the differential conductivity of nanotubes and nanowires. Results reported in the last two to three years are emphasized, highlighting some current trends in the development of sensors for applications such as diagnostics, process monitoring, and security.
Synthetic cannabinoid WIN55,212‐2 inhibits generation of inflammatory mediators by IL‐1β‐stimulated human astrocytes
Authors: Sheng Wen S. , Hu Shuxian , Min Xinan , Cabral Guy A. , Lokensgard James R. , Peterson Phillip K.
Published: September 2004

Activated glial cells have been implicated in the neuropathogenesis of many infectious and inflammatory diseases of the brain. A number of inflammatory mediators have been proposed to play a role in glial cell‐related brain damage; e.g., free radicals such as nitric oxide (NO), cytokines, and chemokines. Our laboratory has been interested in the effect of psychoactive drugs and their derivatives on the production of these mediators. Cannabinoids have been shown to possess immunomodulatory as well as psychoactive properties. We previously have shown that interleukin (IL)‐1β‐stimulated human astrocytes, but not microglia, produce NO. In this study, we investigated the effects of the synthetic cannabinoid WIN55,212‐2 on the production of several key inflammatory mediators by human fetal astrocytes activated by IL‐1β. Expression of the cannabinoid receptors CB1 and CB2 was detected on human astrocytes. WIN55,212‐2 (10−5 M) potently inhibited inducible NO synthase (iNOS) and corresponding NO production by IL‐1β‐stimulated astrocytes. The CB1 and CB2 receptor‐specific antagonists SR141716A and SR144528, respectively, partially blocked this suppressive effect. In addition, treatment of astrocytes with WIN55,212‐2 downregulated in a concentration‐dependent manner IL‐1β‐induced tumor necrosis factor (TNF)‐α release. Treatment with WIN55,212‐2 also inhibited production of the chemokines CXCL10, CCL2 and CCL5 by IL‐1β‐activated astrocytes. These findings indicate that WIN55,212‐2 inhibits the production of inflammatory mediators by IL‐1β‐stimulated human astrocytes and suggest that comparable agents may have therapeutic potential for the management of brain inflammation. © 2004 Wiley‐Liss, Inc.
Sodium channels contribute to microglia/macrophage activation and function in EAE and MS
Authors: Craner Matthew J. , Damarjian Tina G. , Liu Shujun , Hains Bryan C. , Lo Albert C. , Black Joel A. , Newcombe Jia , Cuzner M. Louise , Waxman Stephen G.
Published: September 2004

Loss of axons is a major contributor to nonremitting deficits in the inflammatory demyelinating disease multiple sclerosis (MS). Based on biophysical studies showing that activity of axonal sodium channels can trigger axonal degeneration, recent studies have tested sodium channel‐blocking drugs in experimental autoimmune encephalomyelitis (EAE), an animal model of MS, and have demonstrated a protective effect on axons. However, it is possible that, in addition to a direct effect on axons, sodium channel blockers may also interfere with inflammatory mechanisms. We therefore examined the novel hypothesis that sodium channels contribute to activation of microglia and macrophages in EAE and acute MS lesions. In this study, we demonstrate a robust increase of sodium channel Nav1.6 expression in activated microglia and macrophages in EAE and MS. We further demonstrate that treatment with the sodium channel blocker phenytoin ameliorates the inflammatory cell infiltrate in EAE by 75%. Supporting a role for sodium channels in microglial activation, we show that tetrodotoxin, a specific sodium channel blocker, reduces the phagocytic function of activated rat microglia by 40%. To further confirm a role of Nav1.6 in microglial activation, we examined the phagocytic capacity of microglia from med mice, which lack Nav1.6 channels, and show a 65% reduction in phagocytic capacity compared with microglia from wildtype mice. Our findings indicate that sodium channels are important for activation and phagocytosis of microglia and macrophages in EAE and MS and suggest that, in addition to a direct neuroprotective effect on axons, sodium channel blockade may ameliorate neuroinflammatory disorders via anti‐inflammatory mechanisms. © 2004 Wiley‐Liss, Inc.
Intact signaling by transforming growth factor β is not required for termination of liver regeneration in mice
Authors: Oe Shoshiro , Lemmer Eric R. , Conner Elizabeth A. , Factor Valentina M. , Levéen Per , Larsson Jonas , Karlsson Stefan , Thorgeirsson Snorri S.
Published: September 2004

Transforming growth factor β (TGF-β) is a potent inhibitor of hepatocyte proliferation in vitro and is suggested to be a key negative regulator of liver growth. To directly address the role of TGF-β signaling in liver regeneration in vivo, the TGF-β type II receptor gene (Tgfbr2) was selectively deleted in hepatocytes by crossing “floxed” Tgfbr2 conditional knockout mice with transgenic mice expressing Cre under control of the albumin promoter. Hepatocytes isolated from liver-specific Tgfbr2 knockout (R2LivKO) mice were refractory to the growth inhibitory effects of TGF-β1. The peak of DNA synthesis after 70% partial hepatectomy occurred earlier (36 vs. 48 hours) and was 1.7-fold higher in R2LivKO mice compared with controls. Accelerated S-phase entry by proliferating R2LivKO hepatocytes coincided with the hyperphosphorylation of Rb protein and the early upregulation of cyclin D1 and cyclin E. However, by 120 hours after partial hepatectomy, hepatocyte proliferation was back to baseline in both control and R2LivKO liver. Regenerating R2LivKO liver showed evidence of increased signaling by activin A and persistent activity of the Smad pathway. Blockage of activin A signaling by the specific inhibitor follistatin resulted in increased hepatocyte proliferation at 120 hours, particularly in R2LivKO livers. In conclusion, TGF-β regulates G1 to S phase transition of hepatocytes, but intact signaling by TGF-β is not required for termination of liver regeneration. Increased signaling by activin A may compensate to regulate liver regeneration when signaling through the TGF-β pathway is abolished, and may be a principal factor in the termination of liver regeneration. (Hepatology 2004.)
Immunomodulating Steroidal Glycosides from the Roots of Stephanotis mucronata
Authors: Ye Yiping , Li Xiaoyu , Sun Hongxiang , Chen Fengyang , Pan Yuanjian
Published: September 2004

Guided by in vitro immunological tests, three immunomodulating steroidal glycosides, stemucronatosides A (1), B (2), and C (3), were isolated from the roots of Stephanotis mucronata. On the basis of chemical evidence and extensive spectroscopic methods including 1D and 2D NMR, their structures were determined as 12‐O‐deacetylmetaplexigenin 3‐[O‐6‐deoxy‐3‐O‐methyl‐β‐D‐allopyranosyl‐(1→4)‐O‐β‐D‐cymaropyranosyl‐(1→4)‐β‐D‐cymaropyranoside], 12‐O‐deacetylmetaplexigenin 3‐[O‐β‐D‐thevetopyranosyl‐(1→4)‐O‐β‐D‐cymaropyranosyl‐(1→4)‐β‐D‐cymaropyranoside], and metaplexigenin 3‐[O‐β‐D‐glucopyranosyl‐(1→4)‐O‐6‐deoxy‐3‐O‐methyl‐β‐D‐allopyranosyl‐(1→4)‐O‐β‐D‐cymaropyranosyl‐(1→4)‐β‐D‐cymaropyranoside], respectively. These compounds showed immunomodulating activities in vitro.
Proline‐Modified Porphyrin Catalysts for Enantioselective Epoxidations: Design, Synthesis, and Reactivity
Authors: Boitrel Bernard , Baveux‐Chambenoît Valérie , Richard Philippe
Published: September 2004

The syntheses of various strapped and ‘picket‐fence’ chiral porphyrins are described, and their reactivities towards the enantioselective epoxidation of alkenes are reported. Four L‐proline residues provide the chirality for the various meso‐substituted catalysts, which differ by either the spatial arrangement of the stereogenic centers or the nature and length of the straps. The resulting bridged structures possess four amide linkages in each strap, leading to highly rigid molecules with well‐defined geometries whereas the strapped Fe catalysts gave rise to only moderate enantioselectivities, the C2‐symmetrical ones being superior to the D2‐symmetrical compounds. The D2‐symmetrical ‘picket‐fence’ porphyrins were as selective as their strapped counterparts.
Characteristics of titanium‐coated polyester prostheses in the animal model
Authors: Ueberrueck Torsten , Meyer Lutz , Zippel Roland , Gastinger Ingo
Published: September 2004

Commercially available polyester vascular prostheses (n = 6) in the control group (CG) and titanium‐coated vascular prostheses (TP; n = 7) were interposed within the infrarenal aorta of pigs. The respective healing characteristics and patency rates were compared after 3 months. For evaluation purposes, macroscopic, histological, and immunohistochemical criteria were applied. The macroscopic evaluation revealed complete healing of the TP in comparison with the CG. Extraluminal inspection revealed prominent firm cicatricial tissue in the prosthesis bed of the TP group. All TP were occluded. In the CG, occlusion of the prostheses occurred in n = 1 (16 %). On average, neointimal hyperplasia (NIH) in the proximal part of the anastomosis was not significantly different to the CG. The extraluminal proliferation index (Ki67) was reduced in the TP group (p = 0.002). The immunohistochemical analysis of intraluminal changes revealed no significant differences between CG and TP. All of the titanium‐coated polyester vascular prostheses were found to be occluded. The additional coating of polyester prostheses with titanium would not appear to be of any particular benefit. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 173–178, 2005
Cytoprotection by bcl‐2 gene transfer against ischemic liver injuries together with repressed lipid peroxidation and increased ascorbic acid in livers and serum
Authors: Yanada Shinobu , Saitoh Yasukazu , Kaneda Yasufumi , Miwa Nobuhioko
Published: September 2004

The maximum gene exhibition was shown to be achieved at 48 h after transfection with human bcl‐2 (hbcl‐2) genes built in an SV40 early promoter‐based plasmid vector and HVJ‐liposome for cultured rat hepatocytes. The similar procedure of hbcl‐2 transfection was therefore conducted for livers in rats via the portal vein, and after 48 h followed by post‐ischemic reperfusion (I/R) operation for some hepatic lobes. The I/R‐induced hepatic injuries were in situ observed as both cell morphological degeneration and cellular DNA strand cleavages around capillary vessels of the ischemic liver lobes as detected by HE stain and TUNEL assay, and were biochemically observed as release of two hepatic marker enzymes AST and ALT into serum. All the I/R‐induced injuries examined were appreciably repressed for rats transfected with hbcl‐2; hbcl‐2 was expressed in hepatocytes around the capillaries of ischemic regions such as the median lobe and the left lobe, but scarcely around those of non‐ischemic regions. Thus cytoprotection against I/R‐induced injuries may be attributed to the I/R‐promoted expression of transferred hbcl‐2 genes. The possibility was examined firstly by methylphenylindole method, which showed that I/R‐enhanced lipid peroxidation in the reference vector‐transfected livers were markedly repressed in the hbcl‐2‐transfected livers. Contents of ascorbic acid (Asc) in serum and livers of hbcl‐2‐transfected rats were enriched, unexpectedly, versus those of non‐transfected rats, and were as abundant as 1.90‐fold and 1.95‐ to 2.60‐fold versus those in the pre‐ischemic state, respectively. After I/R, an immediate decline in serum Asc occurred in hbcl‐2‐transfectants, and was followed by prompt restoration up to the pre‐ischemic Asc levels in contrast to the unaltered lower Asc levels in non‐transfectants except a transient delayed increase. Hepatic Asc contents were also diminished appreciably at the initial stage after I/R in the ischemic lobes of hbcl‐2‐transfectants, which however retained more abundant Asc versus non‐transfectants especially at the initial I/R stage when scavenging of the oxidative stress should be most necessary for cytoprotection. The results showed a close correlation between cytoprotection by exogenously transferred hbcl‐2 and repressive effects on the lipid peroxidation associated with Asc consumption or redistribution. © 2004 Wiley‐Liss, Inc.
Tumor–host interactions
Authors: Tisdale M.J.
Published: September 2004

A number of malignant tumors interact with the host to cause a syndrome of cachexia, characterized by extensive loss of adipose tissue and skeletal muscle mass, but with preservation of proteins in visceral tissues. Although anorexia is frequently present, the body composition changes in cancer cachexia cannot be explained by nutritional deprivation alone. Loss of skeletal muscle mass is a result of depression in protein synthesis and an increase in protein degradation. The main degradative pathway that has been found to have increased expression and activity in the skeletal muscle of cachectic patients is the ubiquitin‐proteasome proteolytic pathway. Cachexia‐inducing tumors produce catabolic factors such as proteolysis‐inducing factor (PIF), a 24 kDa sulfated glycoprotein, which inhibit protein synthesis and stimulate degradation of intracellular proteins in skeletal muscle by inducing an increased expression of regulatory components of the ubiquitin‐proteasome proteolytic pathway. While the oligosaccharide chains in PIF are required to initiate protein degradation the central polypeptide core may act as a growth and survival factor. Only cachexia‐inducing tumors are capable of elaborating fully glycosylated PIF, and the selectivity of production possibly rests with the acquisition of the necessary glycosylating enzymes, rather than expressing the gene for the polypeptide core. Loss of adipose tissue is probably the result of an increase in catabolism rather than a defect in anabolism. A lipid mobilizing factor (LMF), identical with the plasma protein Zn‐α2‐glycoprotein (ZAG) is found in the urine of cachectic cancer patients and is produced by tumors causing a decrease in carcass lipid. LMF causes triglyceride hydrolysis in adipose tissue through a cyclic AMP‐mediated process by interaction with a β3‐adrenoreceptor. Thus, by producing circulating factors certain malignant tumors are able to interfere with host metabolism even without metastasis to that particular site. © 2004 Wiley‐Liss, Inc.
A fragment of the hypophosphatemic factor, MEPE, requires inducible cyclooxygenase‐2 to exert potent anabolic effects on normal human marrow osteoblast precursors
Authors: Nagel D.E. , Khosla S. , Sanyal A. , Rosen D.M. , Kumagai Y. , Riggs B. Lawrence
Published: September 2004

MEPE, 56.6 kDa protein isolated from tumors associated with hypophosphatemic osteomalacia, increases renal phosphate excretion and is expressed in normal human bone cells. AC‐100, a central 23‐amino acid fragment of MEPE, contains motifs that are important in regulating cellular activities in the bone microenvironment. Thus, we assessed in vitro effects of AC‐100 on multipotential normal human marrow stromal (hMS) cells that have the capacity to differentiate into mature osteoblasts. Proliferation was quantified by [H3]thymidine uptake and cell counting and differentiation by the levels of mRNA for the α2‐chain of type I procollagen (COL1A2), alkaline phosphatase (AP), and osteocalcin (OC) measured using real time reverse transcriptase PCR (RT‐PCR) and by the formation of mineralized nodules. AC‐100 increased proliferation by 257 ± 89% (P < 0.005), increased gene expression of COL1A2 by 339 ± 85% (P < 0.005), AP by 1,437 ± 40% (P < 0.001), and OC by 1,962 ± 337% (P < 0.001). In addition, it increased mineralized nodule formation by 81 ± 14% (P < 0.001) in a dose‐ and time‐dependent fashion. In equimolar dosages, the parent compound, MEPE, had the full activity of the AC‐100 fragment. AC‐100 elicited a comparable response to both IGF‐I and BMP‐2 with respect to proliferation and differentiation of hMS cells. Using gene expression microarray analysis, we demonstrated that AC‐100 increased (by ∼3‐fold) the mRNA for cyclooxgenase‐2 (COX‐2), an inducible enzyme required for prostaglandin synthesis. Moreover, NS‐398, a specific inhibitor of COX‐2 action completely blocked AC‐100‐induced increases in proliferation and differentiation. Thus, AC‐100 has potent anabolic activity on osteoblast precursor cells in vitro and these effects require the induction of COX‐2. © 2004 Wiley‐Liss, Inc.
Role of cell signalling involved in induction of apoptosis by benzo[a]pyrene and cyclopenta[c,d]pyrene in Hepa1c1c7 cells
Authors: Solhaug Anita , Refsnes Magne , Holme Jørn A.
Published: September 2004

The reactive metabolites of benzo[a]pyrene (B[a]P) and cyclopenta[c,d]pyrene (CPP) induced an accumulation/phosphorylation of p53 in Hepa1c1c7 cells, whereas inhibition of p53 reduced the apoptosis. Judged by the inhibiting effect of wortmannin, phosphatidyl‐inositol‐3 (PI‐3) kinases such as DNA‐dependent protein kinase (DNA‐PK), ATM (ataxia‐telangiectasia mutated), and/or ATR (ATM related kinase), appeared to be involved in the DNA damage recognition and the B[a]P‐/CPP‐induced accumulation of p53. B[a]P and CPP also induced phosphorylation of jun‐N‐terminal kinase (JNK) and p38 mitogen activated protein kinase (MAPK). While inhibition of JNK had no effects on the B[a]P‐/CPP‐induced apoptosis, inhibition of p38 MAPK activity reduced this effect. Interestingly, survival signals such as phosphorylation of Akt and Bad seemed to be induced by the B[a]P‐/CPP‐compounds. Furthermore, also extracellular signal‐regulated kinase (ERK)1/2 was activated and seemed to function as a survival signal in B[a]P‐/CPP‐induced apoptosis. © 2004 Wiley‐Liss, Inc.
A novel subfamily of zinc finger genes involved in embryonic development
Authors: Nakamura Mako , Runko Alexander P. , Sagerström Charles G.
Published: September 2004

C2H2 zinc finger proteins make up one of the largest protein families in eukaryotic organisms. Recent study in several different systems has identified a set of novel zinc finger proteins that appear to form a distinct subfamily that we have named the NET family. Members of the NET family (Noc, Nlz, Elbow, and Tlp‐1) share two protein motifs—a buttonhead box and an Sp motif—with zinc finger proteins from the Sp family. However, the NET family is uniquely characterized by a single atypical C2H2 zinc finger, in contrast to the Sp family that contains three tandem C2H2 fingers. Here, we review current information about the biochemical function and in vivo role for members of this subfamily. In general, NET family proteins are required during embryonic development. They appear to act by regulating transcription, most likely as repressors, although they are unlikely to bind DNA directly. In the future, it will be important to directly test if NET family proteins control transcription of specific target genes, perhaps via interactions with DNA‐binding transcription factors, as well as to further explore their function in vivo. © 2004 Wiley‐Liss, Inc.
P2Y receptors play a critical role in epithelial cell communication and migration
Authors: Klepeis Veronica E. , Weinger Ilene , Kaczmarek Elzbieta , Trinkaus‐Randall Vickery
Published: September 2004

Cellular injury induces a complex series of events that involves Ca2+ signaling, cell communication, and migration. One of the first responses following mechanical injury is the propagation of a Ca2+ wave (Klepeis et al. [2001] J Cell Sci 114(Pt 23):4185–4195). The wave is generated by the extracellular release of ATP, which also induces phosphorylation of ERK (Yang et al. [2004] J Cell Biochem 91(5):938–950). ATP and other nucleotides, which bind to and activate specific purinergic receptors were used to mimic injury. Our goal was to determine which of the P2Y purinergic receptors are expressed and stimulated in corneal epithelial cells and which signaling pathways are activated leading to changes in cell migration, an event critical for wound closure. In this study, we demonstrated that the P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11 receptors were present in corneal epithelial cells. A potency profile was determined by Ca2+ imaging for nucleotide agonists as follows: ATP ≥ UTP > ADP ≥ UDP. In contrast, negligible responses were seen for β,γ‐meATP, a general P2X receptor agonist and adenosine, a P1 receptor agonist. Homologous desensitization of the Ca2+ response was observed for the four nucleotides. However, P2Y receptor internalization and degradation was not detected following stimulation with ATP, which is in contrast to EGFR internalization observed in response to EGF. ATP induced cell migration was comparable to that of EGF and was maximal at 1 μM. Cells exposed to ATP, UTP, ADP, and UDP demonstrated a rapid twofold increase in phosphorylation of paxillin at Y31 and Y118, however, there was no activation elicited by β,γ‐meATP or adenosine. Additional studies demonstrated that wound closure was inhibited by reactive blue 2. These results indicate that P2Y receptors play a critical role in the injury repair process. © 2004 Wiley‐Liss, Inc.
A theoretical study of solvent effects on tautomerism and electronic absorption spectra of 3‐hydroxy‐2‐mercaptopyridine and 2,3‐dihydroxypyridine
Authors: Yan Weizhong , Xue Ying , Zhu Hua , Zeng Jun , Xie Daiqian
Published: September 2004

The tautomerization equilibria of 3‐hydroxy‐2‐mercaptopyridine (HMP) and 2,3‐dihydroxypyridine (DHP) in vacuo and in ethanol solution have been studied using the density functional theory (DFT) at B3LYP/6‐31G(d) level. The results indicate that the thione form of HMP and the keto form of DHP are the most stable tautomers in the equilibrium, and the energy barrier for the thiol–thione and enol–keto proton transfer decreases significantly when the tautomerism is mediated by a specific ethanol molecule in solution. The time‐dependent density functional theory—polarizable continuum model (TDDFT‐PCM) calculations on all tautomers of HMP and DHP in vacuo and in ethanol have assigned the lowest π → π* excitations of thione and keto tautomers to the observed absorption bands of HMP and DHP in solutions. The solvation is predicted to have relatively small effect on these π → π* excitations in ethanol. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1833–1839, 2004
Fast fragments: The development of a parallel effective fragment potential method
Authors: Netzloff Heather M. , Gordon Mark S.
Published: September 2004

The Effective Fragment Potential (EFP) method for solvation decreases the cost of a fully quantum mechanical calculation by dividing a chemical system into anab initioregion that contains the solute plus some number of solvent molecules, if desired, and an “effective fragment” region that contains the remaining solvent molecules. Interactions introduced with this fragment region (for example, Coulomb and polarization interactions) are added as one‐electron terms to the total system Hamiltonian. As larger systems and dynamics are just starting to be studied with the EFP method, more needs to be done to decrease the calculation time of the method. This article considers parallelization of both the EFP fragment‐fragment and mixed quantum mechanics (QM)‐EFP interaction energy and gradient computation within the GAMESS suite of programs. The iteratively self‐consistent polarization term is treated with a new algorithm that makes use of nonblocking communication to obtain better scalability. Results show that reasonable speedup is achieved with a variety of sizes of water clusters and number of processors. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1926–1935, 2004
Hypergravity decreases carbonic anhydrase‐reactivity in inner ear maculae of fish
Authors: Anken Ralf H. , Beier Marion , Rahmann Hinrich
Published: September 2004

Previous investigations revealed that fish inner ear otolith growth depends on the amplitude and the direction of gravity. Both otolith total size, otolith bilateral size‐asymmetry and the total and bilateral calcium‐incorporation are also affected by gravity. Hypergravity, e.g., slows down otolith growth and diminishes bilateral otolith asymmetry as compared to 1 g control specimens raised in parallel. Since the enzyme carbonic anhydrase (CA) plays a prominent role in otolithic calcification, the reactivity of inner ear CA during otolith growth under hypergravity was investigated. CA‐reactivity was demonstrated histochemically and densitometrically on sections of inner ear maculae of larval cichlid fish (Oreochromis mossambicus), that were kept for 6 hrs in a 3 g hypergravity centrifuge. The total unilateral macular CA‐reactivity and the bilateral difference in CA between the left and the right maculae were significantly lower in 3 g animals than in 1g controls. The result is in complete agreement with previous studies indicating that a regulatory mechanism, which adjusts otolith size and asymmetry towards the gravity vector, acts via activation/deactivation of macular CA. J. Exp. Zool. 301A:815–819, 2004. © 2004 Wiley‐Liss, Inc.
Anatomy of and patterns of water currents through the mantle cavities of pleurotomariid gastropods
Authors: Voltzow Janice , Morris Paul J. , Linsley Robert M.
Published: September 2004

The paired pallial organs of pleurotomariids (slit shells) are generally interpreted as representing the primitive gastropod condition. Relatively few individual pleurotomariids have been observed alive; most anatomical descriptions have been based on retracted, preserved material. In this study, live animals were observed in still and moving water, videotaped, photographed, and relaxed prior to anatomical description. The pleurotomariid Perotrochus maureri formed a siphon with its mantle at the posterior end of the slit in the shell. As expected, water was expelled from the mantle cavity through this siphon. Dye released along the aperture, the area traditionally considered to be the incurrent window, was never observed to enter the mantle cavity. Instead, water entered through the slit just anterior to the siphon. A similar pattern was observed in the deep‐slit pleurotomariid Entemnotrochus adansonianus. Thus the “anal” slit provided the sites for the incurrent as well as the excurrent windows. This surprising flow pattern is inconsistent with the traditional scenario of early gastropod evolution. J. Morphol. 262:659–666, 2004. © 2004 Wiley‐Liss, Inc.
Evaluation of [Gd(Bz‐TTDA)]2– as a potential contrast agent in MR imaging of the hepatobiliary system: An animal study
Authors: Hsu Jui‐Sheng , Jaw Twei‐Shiun , Liu Gin‐Chung , Wang Yun‐Ming , Chen Shih‐Hsien , Kuo Yu‐Ting , Jao Jo‐Chi , Li Chun‐Wei , Tsai Kun‐Bow
Published: September 2004

Purpose

To evaluate the potential of a new lipophilic paramagnetic complex [Gd(Bz‐TTDA)]2– [(4s)‐4‐benzyl‐3,6,10‐tri(carboxymethyl)‐3,6,10‐triazadodecandioic acid]2– designed for use as a hepatobiliary MR contrast agent.

Materials and Methods

MR imaging studies for normal and hepatocellular carcinoma (HCC) rat models were performed using a 1.5‐T scanner. Sequential multislice T1‐weighted turbo field echo (TFE) (TR/TE/flip angle: 15 msec/6.1 msec/25°) coronal images of normal rats were obtained before and after intravenous injections of 0.1 mmol/kg [Gd(Bz‐TTDA)]2– in study groups (N = 12) or 0.1 mmol/kg gadopentate dimeglumine (Gd‐DTPA)2– in control groups (N = 12). Similar protocols of MR imaging with additional T2‐weighted images were used for the rats with implanted HCC in both study and control groups (N = 12, in each group). MR images were analyzed to evaluate the time‐enhancement change (% increase of signal‐to‐noise ratio [SI/N]) in normal liver, renal cortex, renal medulla, and tumors. The liver‐lesion contrast‐to‐noise ratios (CNR) were also evaluated in study and control groups. The rats were killed immediately after the last MR scan to undergo autopsy and histopathologic observation. The acute toxicity test (medial lethal dose, LD50) in mice was also done.

Results

The liver enhancement in normal rats reached a plateau 5–50 minutes after injection of [Gd(Bz‐TTDA)]2–, maintained for three hours, then gradually declined. Intensity of enhancement in liver, renal cortex, and medulla after injection of [Gd(Bz‐TTDA)]2– was significantly higher than with Gd‐DTPA. The efficacy of tumor characterization with injection of [Gd(Bz‐TTDA)]2– was similar to that of Gd‐DTPA at the early dynamic phase of the contrast study. However, the liver‐lesion CNRs were significantly higher in the study group in the later phase, when tumor enhancement decreased and liver enhancement persisted. The dose of LD50 in acute toxicity test of [Gd(Bz‐TTDA)]2– in mice was 7.5 mmol/kg.

Conclusion

The preliminary results in this animal study indicated that [Gd(Bz‐TTDA)]2– has the potential of becoming a reliable liver MR contrast agent. J. Magn. Reson. Imaging 2004;20:632–639. © 2004 Wiley‐Liss, Inc.
Interleaved echo‐planar imaging for fast multiplanar magnetic resonance temperature imaging of ultrasound thermal ablation therapy
Authors: Stafford R. Jason , Price DVM Roger E. , Diederich Chris J. , Kangasniemi Marko , Olsson Lars E. , Hazle John D.
Published: September 2004

Purpose

To develop a multiplanar magnetic resonance temperature imaging (MRTI) technique based on interleaved gradient‐echo echo‐planar imaging (EPI), verify in phantom, develop software tools to process and display data on a clinical scanner in near real‐time, and demonstrate feasibility to monitor ultrasound thermal ablation therapy in vivo.

Materials and Methods

Temperature estimation used complex phase‐difference subtraction of the EPI MRTI data to indirectly measure the temperature‐dependent water proton‐resonance‐frequency shift. Software tools were developed to run on a clinical 1.5‐T MR scanner that processed and displayed relevant temperature and thermal dosimetry data during the course of thermal ablation treatments in canine brain and prostate in vivo.

Results

EPI MRTI provided multi‐planar acquisitions and increased temperature sensitivity and lipid suppression. Relative to a single‐plane fast gradient‐echo MRTI sequence at comparable spatial and temporal resolutions in phantom, EPI MRTI demonstrated a three‐fold increase in sensitivity and slice coverage per TR. In vivo monitoring of ultrasound thermal ablation therapy in canine brain and prostate demonstrated the usefulness of the temperature and thermal dose information.

Conclusion

Multi‐planar MRTI allowed progression of thermal damage to be monitored and treatment parameters adjusted in near real‐time (less than five second delay). EPI MRTI is an effective multi‐planar monitoring method during ultrasound thermal ablation procedures. J. Magn. Reson. Imaging 2004;20:706–714. © 2004 Wiley‐Liss, Inc.
Robust field map generation using a triple‐echo acquisition
Authors: Windischberger Christian , Robinson Simon , Rauscher Alexander , Barth Markus , Moser Ewald
Published: September 2004

Purpose

To establish a fast and robust technique for generating magnetic field maps for the correction of geometric distortions in echo‐planar magnetic resonance (MR) images.

Materials and Methods

Multislice gradient‐echo (GE) images were acquired at echo times of 6, 6.5, and 7.5 msec in order to cover a field shift range of ±666 Hz in the resulting B0 maps. To account for possible phase wrap scenarios, seven phase triples were calculated for each pixel. Linear regression of the phase vs. echo time was performed for each set. The slope of the set with the minimum fitting error was taken as the true magnetic field in the respective pixel.

Results

Based on the fitting error distribution, the technique is shown to be feasible and effective for assessing the field distribution in the brain at 3 T, especially in inferior brain areas (amygdalae, hippocampus). Examples of echo‐planar images distortion corrected using the calculated field maps are shown.

Conclusion

The approach presented yields robust estimation of magnetic field maps and requires under a minute of additional acquisition time and only seconds of computational time. As such, it is easily possible to apply image distortion correction in routine functional MR imaging (fMRI) studies, enabling improved coregistration of brain activation maps with structures on anatomical images. J. Magn. Reson. Imaging 2004;20:730–734. © 2004 Wiley‐Liss, Inc.
Automatic registration of brain magnetic resonance images based on Talairach reference system
Authors: Han Yeji , Park HyunWook
Published: September 2004

Purpose

To demonstrate a robust registration method of brain magnetic resonance (MR) images based on the Talairach reference system with automatic determinations of the fiducial points.

Materials and Methods

Eight specified landmark points of the Talairach reference system are determined after successfully extracting the midsagittal plane from three‐dimensional MR imaging (MRI) data. Projection information of the image intensity is used to determine the midline of the cerebrum in axial and coronal view images, which is a necessary step for extraction of the midsagittal plane. To find the landmarks of anterior commissure (AC) and posterior commissure (PC) in the midsagittal plane, we adopt two‐step shape matching that properly finds locations of the corpus callosum (CC), and then AC and PC, respectively. The shape matching is performed on the edge‐enhanced midsagittal plane image to minimize dependency on image intensity variation. Other landmark points of the Talairach reference system are determined by fitting the intensity curve of the cutview with the Gaussian model.

Results

The proposed method automatically determines seven landmark points, except the inferior point (IP), and the brain MR images can be successfully registered with the Talairach reference system.

Conclusion

The suggested registration method can be applied to any MR images for functional studies. It can also be applied to patients unless their brains are highly deformed or have a highly deformed CC. J. Magn. Reson. Imaging 2004;20:572–580. © 2004 Wiley‐Liss, Inc.
Detection and characterization of focal hepatic lesions: Mangafodipir vs. Superparamagnetic iron oxide‐enhanced magnetic resonance imaging
Authors: Kim Myeong‐Jin , Kim Joo Hee , Lim Joon Seok , Oh Young Taik , Chung Jae‐Joon , Choi Jin Sup , Lee Woo Jung , Kim Ki Whang
Published: September 2004

Purpose

To compare the mangafodipir‐enhanced magnetic resonance (MR) and superparamagnetic iron oxide (SPIO)‐enhanced images for their ability to detect and characterize focal hepatic lesions.

Materials and Methods

Unenhanced, mangafodipir‐enhanced, and SPIO‐enhanced hepatic MR images obtained from 64 patients were analyzed. A total of 121 hepatic lesions were included: 66 hepatocellular carcinomas (HCCs), 26 metastases, 14 hemangiomas, 5 cysts, 3 cholangiocarcinomas, 4 focal nodular hyperplasias (FNHs), 2 abscesses, and 1 adenoma. Two radiologists independently reviewed the two sets of images in a random order: 1) the unenhanced and mangafodipir‐enhanced images (the mangafodipir set) and 2) the unenhanced and SPIO‐enhanced images (the SPIO set). This study compared the accuracy of lesion detection, the ability to distinguish between a benign and malignant lesion, and the ability to distinguish between the hepatocellular and nonhepatocellular origins of the lesions using the areas (Az) under the receiver operating characteristic (ROC) curve.

Results

The overall accuracy for detecting focal lesions was significantly higher (P < 0.05) with the SPIO set (Az = 0.846 and 0.871 for readers 1 and 2, respectively) than with the mangafodipir set (Az = 0.716 and 0.766). Most of the lesions detected only with the SPIO‐enhanced MR images by the readers were small HCCs. For lesions larger than 15 mm, the sensitivities of the two contrast enhancement techniques were similar for both readers. The accuracy of the mangafodipir and SPIO sets in distinguishingbetween benign and malignant lesions was comparable. The accuracy for distinguishing between the hepatocellular and nonhepatocellular origins of the lesions was significantly higher (P < 0.05) using the mangafodipir set (Az = 0.897 and 0.946) than using the SPIO set (Az = 0.741 and 0.833).

Conclusion

SPIO‐ and mangafodipir‐enhanced images were comparable for detection of focal hepatic lesions other than small HCCs, which were better detected on the SPIO‐enhanced images. Mangafodipir‐enhanced images are likely better than the SPIO‐enhanced images for distinguishing between focal liver lesions with a hepatocellular or nonhepatocellular origin. J. Magn. Reson. Imaging 2004;20:612–621. © 2004 Wiley‐Liss, Inc.
Fish protein hydrolysates from gold carp (Carassius auratus): I. A study of hydrolysis parameters using response surface methodology
Authors: Sumaya‐Martínez Teresa , Castillo‐Morales Alberto , Favela‐Torres Ernesto , Huerta‐Ochoa Sergio , Prado‐Barragán Lilia Arely
Published: September 2004

The combined effects of pH, temperature (T), substrate/buffer ratio (S:B) and enzyme concentration (E) on protein recovery from gold carp (Carassius auratus) processing waste with Flavourzyme® were characterised. The effect of hydrolysis parameters on the degree of hydrolysis (DH) was described through response surface analysis (RSA) and the model obtained was defined as follows: DH = −316.30 + 7.1T + 44.5pH + 0.292S:B + 0.27E − 0.048T2 − 2.407pH2 − 0.002S:B2 − 0.307TxpH − 0.002S:BxE. All regression coefficients were significant (α = 0.05). The model showed a good fit with the experimental data, since the R2 of 0.923 indicated that 92.3% of the variability within the range of values studied could be explained by the model. The mathematical model presented a plateau region with a maximum DH (>26.6%) at the following critical values: pH = 5.9, T = 53 °C, S:B = 14.7% and E = 80 LAPU (leucine aminopeptidase units) g−1. Electrophoretic (SDS‐PAGE) patterns showed a progressive reduction in molecular weight of the peptidic fractions from 10 min of hydrolysis onwards. By controlling the enzymatic process, it was possible to predict the molecular weight of the peptides obtained, in turn affecting the functional and nutritional properties of the peptidic fractions. Copyright © 2004 Society of Chemical Industry
Effects of temperature, shear rate and constituents on rheological properties of tahin (sesame paste)
Authors: Lokumcu Altay Filiz , Ak M Mehmet
Published: September 2004

In this paper, rheological properties of tahin are reported at temperatures from 20 to 70 °C and shear rates in the range 0.13–500 s−1. Temporary hysteresis loops were observed in the first cycle of the flow curves. The steady shear behaviour of tahin was pseudoplastic and described by a power law model. The consistency coefficient exhibited strong temperature dependence for which the activation energy of flow was 21.6 kJ mol−1. The flow behaviour index of tahin tended to increase whereas the consistency coefficient tended to decrease during storage at room temperature. Tahin oil exhibited Newtonian behaviour with a strong dependence of viscosity on temperature. The activation energy of flow for tahin oil was 35.7 kJ mol−1. While reconstituted suspensions containing up to 20% solids exhibited Newtonian behaviour, those with more solids and the original tahin showed pseudoplastic behaviour. The Krieger–Dougherty model fitted the suspension viscosity data well. Below 20% solids level there was no effect of particle size on the viscosity of the reconstituted suspensions. It was shown that for the same amount of solids the viscosity of a ‘polydisperse’ suspension was lower than that of a ‘monodisperse’ suspension. Copyright © 2004 Society of Chemical Industry
Therapeutic ratio quantifies laser antisepsis: Ablation of Porphyromonas gingivalis with dental lasers
Authors: Harris David M. , Yessik Michael
Published: September 2004

Background and Objectives

It is established that both pulsed Nd:YAG (1,064 nm) and continuous diode (810 nm) dental lasers kill pathogenic bacteria (laser antisepsis), but a quantitative method for determining clinical dosimetry does not exist. The purpose of this study was to develop a method to quantify the efficacy of ablation of Porphyromonas gingivalis (Pg) in vitro for two different lasers.

Study Design/Materials and Methods

The ablation thresholds for the two lasers were compared in the following manner. The energy density was measured as a function of distance from the output of the fiber‐optic delivery system. Pg cultures were grown on blood agar plates under standard anaerobic conditions. Blood agar provides an approximation of gingival tissue for the wavelengths tested in having hemoglobin as a primary absorber. Single pulses of laser energy were delivered to Pg colonies and the energy density was increased until the appearance of a small plume was observed coincident with a laser pulse. The energy density at this point defines the ablation threshold. Ablation thresholds to a single pulse were determined for both Pg and for blood agar alone.

Results

The large difference in ablation thresholds between the pigmented pathogen and the host matrix for pulsed‐Nd:YAG represented a significant therapeutic ratio and Pg was ablated without visible effect on the blood agar. Near threshold the 810‐nm diode laser destroyed both the pathogen and the gel.

Conclusions

Clinically, the pulsed Nd:YAG may selectively destroy pigmented pathogens leaving the surrounding tissue intact. The 810‐nm diode laser may not demonstrate this selectivity due to its greater absorption by hemoglobin and/or longer pulse duration. Lasers Surg. Med. 35:206–213, 2004. © 2004 Wiley‐Liss, Inc.