bluuebunny/crossref_metadata_2025 huggingface dataset:
A 5‐year study of the prevalence and genetic diversity of human caliciviruses associated with sporadic cases of acute gastroenteritis in young children admitted to hospital in Melbourne, Australia (1998–2002)
Authors: Kirkwood Carl D. , Clark Ruth , Bogdanovic‐Sakran Nada , Bishop AO Ruth F.
Published: July 2005

The prevalence and genetic diversity of human caliciviruses causing sporadic cases of acute gastroenteritis in young children hospitalized in a large pediatric hospital in Melbourne, Australia over 5 years (incorporating January 1998–December 2002) was studied by reverse transcription and sequence analysis of part of the polymerase gene. The overall prevalence of calicivirus infection in children aged <5 years during the 5 year study was 9.2% (113/1,233), with 95% of the strains belonging to the Norovirus genera. Strains of the norovirus G11‐4 cluster were the most common type identified in 4 of the 5 years studied (1998, 1999, 2001, and 2002), with strains of norovirus cluster G11‐5 the most common type during 2000. Additional norovirus genetic clusters GI‐3, GII‐1, GII‐2, GII‐3, GII‐6, and GII‐7, were also identified, but comprised only 17/94 of norovirus genogroup II strains. Five sapovirus strains were also identified. These results highlight the divergence of norovirus strains identified in a pediatric population. J. Med. Virol. 77:96–101, 2005. © 2005 Wiley‐Liss, Inc.
Presence and type of oncogenic human papillomavirus in classic and in differentiated vulvar intraepithelial neoplasia and keratinizing vulvar squamous cell carcinoma
Authors: Bonvicini F. , Venturoli S. , Ambretti S. , Paterini P. , Santini D. , Ceccarelli C. , Zerbini M. , Musiani M.
Published: July 2005

The presence and type of oncogenic papillomavirus (HPV) in classic warty/basaloid vulvar intraepithelial neoplasia and in differentiated vulvar intraepithelial neoplasia and keratinizing vulvar squamous cell carcinoma was investigated using three techniques, that is, histology, in situ hybridization, and PCR–ELISA. HPV typing was performed using in situ hybridization and PCR–ELISA. Differentiated vulvar intraepithelial neoplasia and invasive keratinizing vulvar squamous cell carcinoma proved completely negative for HPV by PCR–ELISA, in situ hybridization, and histologic examination, while in classic vulvar intraepithelial neoplasia, a HPV positivity of 66.1% was found. HPV 16 was the predominant type, with HPV 35, 33, and 52 types found rarely and sometimes together with HPV 16. PCR–ELISA proved to be the most suitable method to detect and type mucosal oncogenic HPVs. The absolute absence of HPV DNA in differentiated vulvar intraepithelial neoplasias and in keratinizing vulvar squamous cell carcinoma suggests a strong HPV‐independent pathway of malignant progression to invasive carcinoma. J. Med. Virol. 77:102–106, 2005. © 2005 Wiley‐Liss, Inc.
Candidate human papillomavirus (HPV) type 27b: Nucleotide sequence and heterogeneity with HPV 27
Authors: Yamaguchi Taihei , Miwa Yoko , Eizuru Yoshito
Published: July 2005

More than 100 human papillomavirus (HPV) types have been reported as tumorigenic agents. HPV types 2 and 27 were identified in benign tumors and classified closely according to the sequence homology. An HPV type 2 related sequence was identified previously in an oral papilloma. However, the correct typing and sequencing was impossible at that time. A candidate HPV was cloned by the long‐PCR technique from an oral papilloma and characterized by nucleotide sequence. This virus was basically HPV type 27, but there was some heterogeneity in comparison with the prototype. Most differences were nucleotide‐sequence variations. Two of four‐nucleotide insertions were frame shift, resulting in longer L1 protein than that of HPV 27. J. Med. Virol. 77:113–115, 2005. © 2005 Wiley‐Liss, Inc.
Norwalk virus infection associates with secretor status genotyped from sera
Authors: Hutson Anne M. , Airaud Fabrice , LePendu Jacques , Estes Mary K. , Atmar Robert L.
Published: July 2005

ABO histo‐blood group type and secretor status are two genetically determined factors that contribute to resistance and susceptibility to Norwalk virus (NV). Archived serum samples but not saliva samples are available from NV and many other norovirus challenge studies and outbreaks. A person's ABO phenotype is easily determined from their archived sera, but the individual's secretor phenotype cannot easily be ascertained without saliva. We now report that a person's secretor genotype can also be determined from the archived serum samples. Of the 51 volunteers who participated in a NV challenge study, all eight non‐secretors were resistant to NV infection, all of the 42 NV‐infected volunteers were secretor positive, and a single uninfected secretor was histo‐blood group type B. In agreement with a previous report, secretor status was most predictive of risk of NV infection. The methods described in this report should rapidly improve our knowledge of the associations between carbohydrate antigen expression and susceptibility to different strains of the non‐cultivatable noroviruses by enabling retrospective studies from previously collected volunteer challenge and outbreak sera. J. Med. Virol. 77:116–120, 2005. © 2005 Wiley‐Liss, Inc.
Detection of respiratory syncytial virus genome by subgroups‐A, B specific reverse transcription loop‐mediated isothermal amplification (RT‐LAMP)
Authors: Ushio Masanobu , Yui Ikuko , Yoshida Naoko , Fujino Motoko , Yonekawa Toshihiro , Ota Yoshinori , Notomi Tsugunori , Nakayama Tetsuo
Published: July 2005

Annual seasonal outbreaks of respiratory syncytial virus (RSV) infection occur every winter. Most patients are diagnosed clinically by a rapid detection kit for RSV protein(s) from nasopharyngeal secretion (NPS), but some problems have been reported on the specificity and sensitivity of such rapid detection kits. To ratify these issues, a sensitive, specific, simple, and rapid molecular based diagnostic method is expected to be introduced and we have developed a method to detect the RSV genome of subgroups A and B independently by reverse transcription loop‐mediated isothermal amplification (RT‐LAMP). We detected the genomic RNA corresponding approximately to 0.1 TCID 50 in the sample by RT‐LAMP for both RSV subgroups under isothermal condition within 60 min after extraction of RNA. Specific DNA amplification was monitored by a real‐time turbidimeter and the quantity of RNA was calculated. The RSV genome was detected in 47 of 50 NPS by RT‐LAMP, and in 42 by nested RT‐PCR, whereas virus isolation was positive for 29 and enzyme‐linked immunoassay (EIA) for 34. RSV subgroup A was detected in 25 by RSV RT‐LAMP A, RSV subgroup B in 23 by RSV RT‐LAMP B, and dual infection with RSV subgroups A and B was identified in one case. They were confirmed with digestion with a specific restriction enzyme, Bgl II. The results showed the potential clinical feasibility of RT‐LAMP as a useful diagnostic tool for the detection of RSV with high sensitivity similar to nested RT‐PCR. J. Med. Virol. 77:121–127, 2005. © 2005 Wiley‐Liss, Inc.
Replication of TT virus in hepatocyte and leucocyte cell lines
Authors: Desai Mayura , Pal Ramprasad , Deshmukh Ranjana , Banker Dushyant
Published: July 2005

The TT virus (TTV) is a non‐enveloped, single‐stranded, circular, DNA virus, first isolated from a patient with hepatitis of unexplained etiology. The much deliberated pathological role of the virus continues to be conjectural in the absence of a suitable in vitro replication model. So far, the liver and the bone marrow have been shown to be the main sites of TTV replication. In this study, the human cell lines HepG2 and Chang Liver, the rat hepatoma cell line MH1C1, phytohemagglutinin (PHA)‐stimulated TTV‐negative peripheral blood mononuclear cell (PBMC) cultures and the B lymphoblast cell line, Raji were investigated as potential in vitro replication systems for TTV. The cell lines were infected with an inoculum prepared by pooling TTV genotype1 DNA positive sera and monitored for virus replication. Of the three hepatocyte cell lines, while the HepG2 and MH1C1 cell lines did not support TTV replication, the Chang Liver cell line showed clear morphological changes as a result of the in vitro infection, which included clumping and granular degeneration of the entire cell sheet over a period of 6 days. The infected cells also showed presence of virus‐specific mRNA representative of viral transcription. The consistent presence of infectious viral particles in the supernatant culture fluid at 24‐hr fluid replacement intervals indicated limited extra‐cellular release of viral particles. The PHA‐stimulated TTV‐negative PBMC cultures and the Raji cell line were also able to support TTV replication and released significant levels of infectious viral particles into the supernantant culture fluid. J. Med. Virol. 77:136–143, 2005. © 2005 Wiley‐Liss, Inc.
cDNA microarray analysis of HBV transgenic mouse liver identifies genes in lipid biosynthetic and growth control pathways affected by HBV
Authors: Hajjou Mustapha , Norel Raquel , Carver Robert , Marion Patricia , Cullen John , Rogler Leslie E. , Rogler Charles E.
Published: July 2005

Hepatitis B virus (HBV) transgenic mice that replicate HBV in the liver generally do not exhibit gross liver pathology, while maintaining a high level (107 or greater) of viral titer in the blood. We have used this model to determine the minimum effects of HBV replication in the liver on cellular gene transcription, using cDNA microarrays. cDNA microarray data from sets of HBV versus control cDNA microarrays revealed a very small impact of HBV on the cellular transcriptome. After deletion of genes that were variable in control cDNA microarrays and applying significance analysis of microarrays (SAM), an application to detect statistically significantly regulated genes, we identified 18 upregulated genes and 14 downregulated genes. Most of the regulated genes show a change in expression with respect to control of less than 40% in either direction, demonstrating small effects of HBV. The largest functional category for upregulated genes was lipid biosynthesis, in which ATP citrate lyase, fatty acid synthase, sterol regulatory element binding factor 2, and retinol binding protein 1 were all upregulated. The most strongly downregulated genes were in the cytochrome p450 group, particularly p450, 4a14. Several growth regulatory genes including cyclin D1, IGF binding protein 3, and PCNA were moderately upregulated. These data are the first to specifically identify enzymes involved in fatty acid and NADPH‐electron transport pathways that are altered by the presence of HBV. The data also demonstrates that HBV is well adapted to non‐cytopathic replication in hepatoctyes. Cellular genes expected to be affected by viral secretion from membranes are clearly upregulated, and upregulation of growth regulatory genes may facilitate replacement of dying hepatocytes during persistent infection. J. Med. Virol. 77:57–65, 2005. © 2005 Wiley‐Liss, Inc.
Solid phase microextraction of stale flavour volatiles from the headspace of UHT milk
Authors: Perkins Melinda L , D'Arcy Bruce R , Lisle Allan T , Deeth Hilton C
Published: July 2005

Solid phase microextraction (SPME) offers a solvent‐free and less labour‐intensive alternative to traditional flavour isolation techniques. In this instance, SPME was optimised for the extraction of 17 stale flavour volatiles (C3–11,13 methyl ketones and C4–10 saturated aldehydes) from the headspace of full‐cream ultrahigh‐temperature (UHT)‐processed milk. A comparison of relative extraction efficiencies was made using three fibre coatings, three extraction times and three extraction temperatures. Linearity of calibration curves, limits of detection and repeatability (coefficients of variation) were also used in determining the optimum extraction conditions. A 2 cm fibre coating of 50/30 µm divinylbenzene/Carboxen/polydimethylsiloxane in conjunction with a 15 min extraction at 40 °C were chosen as the final optimum conditions. This method can be used as an objective tool for monitoring the flavour quality of UHT milk during storage. Copyright © 2005 Society of Chemical Industry
Heat stress reduces the accumulation of rosmarinic acid and the total antioxidant capacity in spearmint (Mentha spicata L)
Authors: Fletcher Ronald S , Slimmon Tannis , McAuley Colette Y , Kott Laima S
Published: July 2005

Selected high‐phenolic lines of spearmint were subjected to a constant 30 °C heat regimen for a period of 4 weeks to determine the effects of heat stress on soluble phenolics, phenols and rosmarinic acid biosynthesis and antioxidant capacity. Heat stress significantly reduced levels of total phenolic acids (71–87%) and soluble phenols (75–87%). This loss was concomitant with a loss of total antioxidant capacity of 21–60% after week 1 and up to 95% by week 4. High‐performance liquid chromatography profiling of heat‐stressed plants at 270 and 320 nm detected nearly a complete loss of rosmarinic acid in all seven chemotypes. High‐temperature drying of non‐heat‐stressed plants at 80 °C resulted in a similar loss of total antioxidant capacity and rosmarinic acid content an effect not observed in material that was subjected to low‐temperature drying first, followed by exposure to high temperature. This suggests that heat stress negatively regulates rosmarinic acid biosynthesis and causes a potential rapid biological breakdown of rosmarinic acid in tissues. 2,2‐Diphenyl‐1‐picrylhydrazyl radical assays of heat‐stressed and non‐stressed plants clearly show that rosmarinic acid is the major contributor to the antioxidant capacity in spearmint. Copyright © 2005 Society of Chemical Industry
Fluorimetric studies and noncovalent labeling of protein with the near‐infrared dye HITCI for analysis by CE‐LIF
Authors: Yan Weiying , Colyer Christa L.
Published: July 2005

1,1′,3,3,3′,3′‐Hexamethylindotricarbocyanine iodide (HITCI) is a commercially available, positively charged, indocarbocyanine dye used typically as a laser dye in the near infrared (NIR). The absorbance and fluorescence properties of HITCI in a variety of solvent systems were determined. Results indicate that the fluorescence of HITCI is not significantly affected by the pH. Titration of HITCI with human serum albumin (HSA) and trypsinogen was carried out to investigate the interactions between this dye and proteins. These studies revealed that the absorbance and fluorescence properties of the dye change upon binding to protein in a wide range of solution pH's. The potential use of HITCI as a noncovalent protein labeling probe, therefore, was explored. Determination and separation of HITCI and HITCI‐protein complexes was performed by capillary electrophoresis with diode‐laser induced fluorescence detection (CE‐LIF). Both pre‐column and on‐column noncovalent labeling methods are demonstrated.
Quantitation of triacylglycerols in plant oils using HPLC with APCI‐MS, evaporative light‐scattering, and UV detection
Authors: Holčapek Michal , Lísa Miroslav , Jandera Pavel , Kabátová Naděžda
Published: July 2005

The main constituents of plant oils are complex mixtures of TGs differing in acyl chain lengths, number and positions of double bonds, and regioisomerism. A non‐aqueous reversed‐phase HPLC method with acetonitrile–2‐propanol gradient and 30+15 cm NovaPak C18columns makes possible an unambiguous identification of the highest number of TGs ever reported for these oils, based on positive‐ion APCI mass spectra. A new approach to TG quantitation is based on the use of response factors with three typical detection techniques for that purpose (APCI‐MS, evaporative light‐scattering detection, and UV at 205 nm). Response factors of 23 single‐acid TGs (saturated TGs from C7 to C22, 7 unsaturated TGs), 4 mixed‐acid TGs, diolein and monoolein are calculated from their calibration curves and related to OOO. Due to differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of TGs. 133 TGs containing 22 fatty acids with 8–25 carbon atoms and 0–3 double bonds are identified and quantified in 9 plant oils (walnut, hazelnut, cashew nut, almond, poppy seed, yellow melon, mango, fig, date) using HPLC/APCI‐MS with a response factor approach. Average parameters and relative fatty acid concentrations are calculated with both HPLC/APCI‐MS and GC/FID.
System peaks and their positive and negative aspects in chromatographic techniques
Authors: Srbek Jan , Coufal Pavel , Bosáková Zuzana , Tesařová Eva
Published: July 2005

Whenever a mobile phase contains more than one component, additional signals commonly called system peaks can appear. The origin of these signals is explained through loss of equilibrium in the separation column caused by injection of analyte dissolved in a different solvent than the mobile phase. The system peaks are then generated by a relaxation process started by the non‐equilibrium state. An overview of the theory and applications of the system peaks in separation methods, mainly in liquid chromatography, is presented in this paper. Only a brief theoretical discussion of the system peak origin is given as the theoretical aspects of system peak formation have already been published in many papers. The main focus of this review is to summarize applications, in which system peaks were used to measure physical or physicochemical data. Signals of system peaks are often misinterpreted but they offer valuable information about thermodynamics and kinetics of the separation process that takes place in chromatographic column.
Zone electrophoresis separation of perfluorocarboxylic acids on a chip with conductivity detection
Authors: Masár Marián , Wójcik Lena , Kaniansky Dušan , Trojanowicz Marek
Published: July 2005

Perfluorinated carboxylic acids (PFCAs), amphiphiles of anthropogenic origin, are spread worldwide throughout the environment. This work deals with their zone electrophoresis (ZE) separation on a chip with coupled columns and integrated conductivity detection. Analogies with the electrophoretic behavior of PFCAs and fatty acids were employed in a search for electrolyte conditions suitable for their separation. ZE separations in the water‐ethanol electrolyte systems, based on differences in the ionic mobilities of the anions of PFCAs, provided favorable resolution and detection conditions of the homologues containing up to 10 carbon atoms in the alkyl chain. Concentration limits of detection of 0.3–6.5 μmol/L were attained for PFCAs (loaded by a 900 nL volume sample injection channel of the chip) under these separation conditions. The material of which the chip was made [poly(methylmethacrylate)] restricted its use in investigations of the separations of higher PFCA homologues as it was damaged by ethanolic and/or methanolic background electrolyte solutions required in experiments with these amphiphilic compounds.
Effect of surfactant counterion and organic modifier on the properties of surfactant vesicles in electrokinetic chromatography
Authors: Schuster Stephanie A. , Foley Joe P.
Published: July 2005

Counterion and organic modifier are two parameters in EKC that can be varied in order to obtain improved solubility, selectivity, and efficiency. The effect of changing surfactant counterion and/or organic modifier on the chromatographic and electrophoretic properties of cetyltrimethylammonium bromide (CTAB)/sodium octyl sulfate (SOS) vesicles is examined in EKC. The vesicles are prepared in a 1:3.66 cationic/anionic mole ratio for a total surfactant concentration of 69 mM. The cationic CTAB is replaced by cetyltrimethylammonium chloride (CTAC) and the first use of CTAC/SOS vesicles is reported. The mean diameter of the CTAC/SOS vesicles is 96 nm while that of the CTAB/SOS vesicles is 85 nm. A class I modifier (2‐amino‐1‐butanol) and a class II modifier (acetonitrile) have similar effects on the EOF, elution range, methylene selectivity, and the efficiency of the CTAB/SOS vesicles and the CTAC/SOS vesicles. Upon addition of 10% ACN, there is roughly a 10‐fold increase in the efficiency of heptanophenone, a model hydrophobic compound, compared to the efficiency using unmodified vesicles. Linear free energy relationship (LFER) analysis using the Abraham solvation model is employed to characterize solute‐vesicle interactions. The results suggest that organic modifier‐vesicle interactions depend somewhat on the counterion.
How different reforestation approaches affect red soil properties in southern China
Authors: Zheng H. , Ouyang Z. Y. , Wang X. K. , Miao H. , Zhao T. Q. , Peng T. B.
Published: July 2005

Significant differences were found in soil physicochemical and biological effects between various forest restoration approaches of a hilly red‐soil region, southern China. Soil quality was the highest in natural secondary forest (0·95), while in sites revegetated with tea‐oil camellia (Camellia oleifera), Chinese fir (Cunninghamia lanceolata) and slash pine (Pinus elliottii) and control sites, integrated soil quality indices were 0·68, 0·55, 0·36 and 0·04 respectively. The lower soil quality of plantations and controls resulted from increased disruption of soil physical structure, lower quality litter fall, lower litter fall production, reduction in microbial biomass, decline of microbial function and loss of soil nutrients due to periodically artificial tending and accelerated soil erosion. Improvement in soil physicochemical properties and enhanced soil microbial function at a natural secondary forest site demonstrated the inherent restoration of these soils. Hence, natural restoration, as well as reducing human disturbance, is a better approach to improving soil properties than returning farmland to planted woodlands. Copyright © 2005 John Wiley & Sons, Ltd.
Reducing water erosion in a gypsic soil by combined use of organic amendment and shrub revegetation
Authors: Marqués M. J. , Jiménez L. , Pérez‐Rodríguez R. , GarcÍa‐Ormaechea S. , Bienes R.
Published: July 2005

Degraded gypsic soils in the centre of Spain can be rehabilitated with organic amendment and shrub revegetation. Erosion has been measured on plots of 2×0·5 m2 under simulated rainfall of 70 mm h−1 and a kinetic energy of 18 J mm−1 m−2. Samples of water runoff and sediments were studied in the summer of the years 2002 and 2003. The presence of shrub Atriplex halimus (Chenonodiaceae) significantly reduces runoff from 16·9 to 6·7 ml m−2 min−1 and sediments from 0·16 to 0·02 g m−2 min−1. When sewage sludge is applied the differences among plots with and without bushes disappear. Although both treatments independently applied are efficient as erosion control measures, the combined use of revegetation and organic amendment allows a reduced dose of sewage sludge with the same effect on erosion. A low dose of sludge is desirable in view of the accumulation of toxic chemicals. Copyright © 2005 John Wiley & Sons, Ltd.
Desertification in north China: background, anthropogenic impacts and failures in combating it
Authors: Chen Y. , Tang H.
Published: July 2005

Desertification in north China is ongoing despite the endeavours to mitigate it over the past 50 years. Overall examination of the context of desertification and defects of desertification‐combating programmes is a prerequisite for desertification control, which is now attracting general concern in China. The physiographic circumstances of north China, including the dry, continental, mid‐latitude climate, easily erodible soil surface and water shortage, provide the background to desertification. Climatic aridity and the evolution of land use and land management in recent decades have produced great stress on the land. The ineffectiveness of anti‐desertification measures ascribed to inadequate scientific involvement in decision‐making, neglect of the human dimension and the lack of a well‐organized desertification monitoring system are discussed in this paper. Copyright © 2005 John Wiley & Sons, Ltd.
Front Cover: Macromol. Chem. Phys. 14/2005
Authors: Lazzari Massimo , Chiantore Oscar , Mendichi Raniero , López‐Quintela M. Arturo
Published: July 2005

Front Cover: Copper‐mediated ATRP in 2‐cyanopyridine permitted the synthesis of challenging PAN‐containing block copolymers through a pathway of general applicability. 1H NMR allowed the determination of structural features as well as enlightening on the termination mechanism, whereas TEM images suggest few of the self‐assembling morphologies which are formed at both in solution (worm‐like micelles in a polystyrene selective solvent) and at the solid state. Further details can be found in the Full Paper by M. Lazzari,* O. Chiantore, R. Mendichi, and M. A. López‐Quintela on page 1382.
Back Cover: Macromol. Chem. Phys. 14/2005
Authors: Carella Antonio , Centore Roberto , Riccio Pierluigi , Sirigu Augusto , Quatela Alessia , Palazzesi Christian , Casalboni Mauro
Published: July 2005

Back Cover: Second order NLO properties of two series of copolymers were investigated. The figure on the cover shows that chromophores with an ethyl substituent on the imidazole unit give polymers with better NLO performances. Further details can be found in the Full Paper by A. Carella, R. Centore,* P. Riccio, A. Sirigu, A. Quatela, C. Palazzesi, and M. Casalboni on page 1399.
Front Cover: Macromol. Rapid Commun. 14/2005
Authors: Jin Yi Zheng , Gao Chao , Kroto Harold W. , Maekawa Toru
Published: July 2005

Front Cover: Carbon spheres were covalently functionalized with polymers by using an in situ atom transfer radical polymerization approach, resulting in significantly improved dispersibility in organic solvents. SEM and TEM observations show a uniform distribution of the carbon spheres in the continuous polymer phase. Further details can be found in the Communication by Y. Z. Jin, C. Gao,* H. W. Kroto, and T. Maekawa on page 1133.
Cover Picture: Macromol. Theory Simul. 6/2005
Authors: Pattanayek Sudip K. , Pereira Gerald G.
Published: July 2005

Cover: Self‐consistent mean field theory and Monte Carlo simulations reveal that strongly adsorbed grafted polymers undergo an instability driven by polymer entropy above some critical grafting separation in the intermediate segregation regime. Two grafted chains form micelles of elliptical shape or an ellipse with tethers (top left). Multi‐chain systems form either a holey layer (top right), lamella layer (bottom left) or circular polymer droplets (bottom right). Color scheme: blue ‐ solvent; red ‐ polymer. Further details can be found in the Full Paper by S. K. Pattanayek* and G. G. Pereira on page 347.
Measurement of skeletal muscle perfusion during postischemic reactive hyperemia using contrast‐enhanced MRI with a step‐input function
Authors: Thompson Richard B. , Aviles Ronnier J. , Faranesh Anthony Z. , Raman Venkatesh K. , Wright Victor , Balaban Robert S. , McVeigh Elliot R. , Lederman Robert J.
Published: July 2005

The regional distribution of skeletal muscle blood flow was measured during postischemic reactive hyperemia using Gd‐DTPA contrast‐enhanced (CE) MRI. The release of an occlusive thigh cuff was used to deliver a step‐input of contrast concentration that was coincident with the onset of reactive hyperemia. A first‐order tracer kinetic equation was used to estimate the unidirectional influx constant, Ki (ml/100 g/min), and the distribution volume of Gd‐DTPA in the tissue, ve, from T1‐weighted images acquired with saturation recovery (SR) steady‐state free precession (SSFP) and spoiled gradient‐echo (SPGR) protocols. The capillary permeability surface (PS) area increased significantly during reactive hyperemia, which facilitated rapid extraction of Gd‐DTPA during the first pass. Regional muscle group studies from 11 normal volunteers yielded blood flow (Ki) values of 108.3 ± 34.1 ml/100 g/min in the gastrocnemius, 184.3 ± 41.3 ml/100 g/min in the soleus, and 122.4 ± 34.4 ml/100 g/min in the tibialis anterior. The distribution volumes (ve) in the corresponding muscle groups were respectively 8.3% ± 2.1%, 9.3% ± 1.9%, and 7.9% ± 1.8% from the kinetic model, and 8.8% ± 2.4%, 9.1% ± 1.9%, and 7.2% ± 1.4% from tissue relaxometry studies. Bulk blood flow studies in the same volunteers using phase‐contrast velocimetry (popliteal artery) yielded significantly lower flow values, but with a correlation coefficient R2 = 0.62 and P = 0.004. Magn Reson Med 54:289–298, 2005. Published 2005 Wiley‐Liss, Inc.
Visibility of vascular phenylalanine in dynamic uptake studies in humans using magnetic resonance spectroscopy
Authors: Kreis Roland , Salvisberg Christian , Lutz Thomas , Boesch Chris , Pietz Joachim
Published: July 2005

In general, vascular contributions to the in vivo magnetic resonance (MR) brain spectrum are too small to be relevant. In cerebral uptake studies, however, vascular contributions may constitute a major confounder. MR visibility of vascular Phe was investigated by recording localized spectra from fully oxygenated and well‐mixed whole blood. Blood Phe levels determined by MR spectroscopy (MRS) and ion‐exchange chromatography showed excellent correlation. In addition, effects of blood flow were shown to have a small effect on signal amplitude with the MRS methodology used. Hence, blood Phe is almost completely MR visible at 1.5 T, even though it is severely broadened at higher fields. Without appropriate correction, cerebral Phe influx in studies of brain Phe uptake in phenylketonuria patients or healthy subjects would appear to be faster and lead to higher levels. Similar effects are envisaged for studies of ethanol or glucose uptake across the blood–brain barrier. Magn Reson Med 54:435–438, 2005. © 2005 Wiley‐Liss, Inc.
Water in tendon: Orientational analysis of the free induction decay
Authors: Krasnosselskaia Lada V. , Fullerton Gary D. , Dodd Stephen J. , Cameron Ivan L.
Published: July 2005

The orientation dependence of the free induction decay (FID) of1H NMR water signal in ex vivo bovine digital flexor tendon at the native level of hydration is reported. Residual dipolar coupling due to the overall tissue anisotropy produces a 6:1 change in the signal intensity as an angle between the long axis of a specimen and the external magnetic field is changed from the “magic angle” of 54.7° to 0°. The strength of residual dipolar interactions between water protons was estimated by orientational analysis of the signal intensity to be equal to 780 Hz. Apparent signal maxima are observed at orientations 8–13° away from 54.7° due to an inhomogeneous contribution to the decay. A small fraction of total water in tendon is detectable at all orientations and exhibits a shift in the precession frequency. It is hypothesized that this water fraction resides in the interconnecting gaps at the ends of collagen molecules. The gaps have a disordered environment that allows for a zero time average of dipolar interactions. Measured frequency and phase shifts are interpreted as signatures of the bulk magnetic susceptibility effect due to geometry of the cavity formed by adjacent gaps at the ends of the collagen molecules. The multiexponentiality of the FID decay is hypothesized to be due to the exchange between orientationally restricted water structured along the length of the collagen molecule and disordered water in the cavity. Magn Reson Med 54:280–288, 2005. © 2005 Wiley‐Liss, Inc.
Application of model‐free analysis in the MR assessment of pulmonary perfusion dynamics
Authors: Chuang Kai‐Hsiang , Wu Ming‐Ting , Lin Yi‐Ru , Hsieh Kai‐Sheng , Wu Ming‐Long , Tsai Shang‐Yueh , Ko Cheng‐Wen , Chung Hsiao‐Wen
Published: July 2005

Dynamic contrast‐enhanced (DCE) MRI has been used to quantitatively evaluate pulmonary perfusion based on the assumption of a gamma‐variate function and an arterial input function (AIF) for deconvolution. However, these assumptions may be too simplistic and may not be valid in pathological conditions, especially in patients with complex inflow patterns (such as in congenital heart disease). Exploratory data analysis methods make minimal assumptions on the data and could overcome these pitfalls. In this work, two temporal clustering methods—Kohonen clustering network (KCN) and Fuzzy C‐Means (FCM)—were concatenated to identify pixel time‐course patterns. The results from seven normal volunteers show that this technique is superior for discriminating vessels and compartments in the pulmonary circulation. Patient studies with five cases of acquired or congenital pulmonary perfusion disorders demonstrate that pathologies can be highlighted in a concise map that combines information of the mean transit time (MTT) and pulmonary blood volume (PBV). The method was found to provide greater insight into the perfusion dynamics that might be overlooked by current model‐based analyses, and may serve as a basis for optimal hemodynamic quantitative modeling of the interrogated perfusion compartments. Magn Reson Med 54:299–308, 2005. © 2005 Wiley‐Liss, Inc.
Functional MRI using regularized parallel imaging acquisition
Authors: Lin Fa‐Hsuan , Huang Teng‐Yi , Chen Nan‐Kuei , Wang Fu‐Nien , Stufflebeam Steven M. , Belliveau John W. , Wald Lawrence L. , Kwong Kenneth K.
Published: July 2005

Parallel MRI techniques reconstruct full‐FOV images from undersampled k‐space data by using the uncorrelated information from RF array coil elements. One disadvantage of parallel MRI is that the image signal‐to‐noise ratio (SNR) is degraded because of the reduced data samples and the spatially correlated nature of multiple RF receivers. Regularization has been proposed to mitigate the SNR loss originating due to the latter reason. Since it is necessary to utilize static prior to regularization, the dynamic contrast‐to‐noise ratio (CNR) in parallel MRI will be affected. In this paper we investigate the CNR of regularized sensitivity encoding (SENSE) acquisitions. We propose to implement regularized parallel MRI acquisitions in functional MRI (fMRI) experiments by incorporating the prior from combined segmented echo‐planar imaging (EPI) acquisition into SENSE reconstructions. We investigated the impact of regularization on the CNR by performing parametric simulations at various BOLD contrasts, acceleration rates, and sizes of the active brain areas. As quantified by receiver operating characteristic (ROC) analysis, the simulations suggest that the detection power of SENSE fMRI can be improved by regularized reconstructions, compared to unregularized reconstructions. Human motor and visual fMRI data acquired at different field strengths and array coils also demonstrate that regularized SENSE improves the detection of functionally active brain regions. Magn Reson Med 54:343–353, 2005. © 2005 Wiley‐Liss, Inc.
Efficiency of inversion pulses for background suppressed arterial spin labeling
Authors: Garcia Dairon M. , Duhamel Guillaume , Alsop David C.
Published: July 2005

Background suppression strategies for arterial spin labeling (ASL) MRI offer reduced noise from motion and other system instabilities. However, the inversion pulses used for suppression can also attenuate the ASL signal, which may offset the advantages of background suppression. Numerical simulations were used to optimize the inversion efficiency of four candidate pulses over a range of radiofrequency (RF) and static magnetic field variations typical of in vivo imaging. Optimized pulses were then used within a pulsed ASL sequence to assess the pulses' in vivo inversion efficiencies for ASL. The measured in vivo inversion efficiency was significantly lower than theoretical predictions (e.g., 93% experimental compared to 99% theoretical) for the tangent hyperbolic pulse applied in a background suppression scheme. This inefficiency was supported by an in vitro study of human blood. These results suggest that slow magnetization transfer (MT) in blood, either with bound water or macromolecular protons, dominates the inversion inefficiency in blood. Despite the attenuated signal relative to unsuppressed ASL, the signal‐to‐noise ratio (SNR) with suppression was improved by 23–110% depending on the size of the region measured. Knowledge of efficiency will aid optimization of the number of suppression pulses and provide more accurate quantification of blood flow. Magn Reson Med 54:366–372, 2005. © 2005 Wiley‐Liss, Inc.
Free‐breathing whole‐heart coronary MRA with 3D radial SSFP and self‐navigated image reconstruction
Authors: Stehning C. , Börnert P. , Nehrke K. , Eggers H. , Stuber M.
Published: July 2005

Respiratory motion is a major source of artifacts in cardiac magnetic resonance imaging (MRI). Free‐breathing techniques with pencil‐beam navigators efficiently suppress respiratory motion and minimize the need for patient cooperation. However, the correlation between the measured navigator position and the actual position of the heart may be adversely affected by hysteretic effects, navigator position, and temporal delays between the navigators and the image acquisition. In addition, irregular breathing patterns during navigator‐gated scanning may result in low scan efficiency and prolonged scan time. The purpose of this study was to develop and implement a self‐navigated, free‐breathing, whole‐heart 3D coronary MRI technique that would overcome these shortcomings and improve the ease‐of‐use of coronary MRI. A signal synchronous with respiration was extracted directly from the echoes acquired for imaging, and the motion information was used for retrospective, rigid‐body, through‐plane motion correction. The images obtained from the self‐navigated reconstruction were compared with the results from conventional, prospective, pencil‐beam navigator tracking. Image quality was improved in phantom studies using self‐navigation, while equivalent results were obtained with both techniques in preliminary in vivo studies. Magn Reson Med 54:476–480, 2005. © 2005 Wiley‐Liss, Inc.
Liver regeneration in humans is characterized by significant changes in cellular phosphorus metabolism: Assessment using proton‐decoupled 31P‐ magnetic resonance spectroscopic imaging
Authors: Zakian Kristen L. , Koutcher Jason A. , Malhotra Sandeep , Thaler Howard , Jarnagin William , Schwartz Lawrence , Fong Yuman
Published: July 2005

In the present study we applied proton‐decoupled 31P magnetic resonance spectroscopic imaging (MRSI) to noninvasively assess liver metabolism in patients who had undergone a partial hepatectomy (PH). Proton‐decoupled 31P chemical shift imaging was performed in 47 patients 2–28 days following major hepatectomy, and the results were compared with those from eight control subjects. All studies were performed on a 1.5T MR imager (General Electric, Milwaukee, WI) equipped with a stand‐alone proton decoupler. A 31P‐1H resonator pair was used for data acquisition, and 31P data were obtained in 34 min. Liver regeneration was characterized by increases in phosphoethanolamine (PE), and decreases in nucleoside triphosphates (NTP), glycerophosphoethanolamine (GPE), and glycerophosphocholine (GPC). These alterations were most marked 48–72 hr after hepatectomy and returned to baseline within 3 weeks. The level of PE measured by MRSI was also found to depend on the percentage of liver that was removed, while changes in levels of cellular high energy phosphates were independent of the size of liver resection. Implementation of proton‐decoupling was critical for assessing individual phosphomonoester and phosphodiester components. This study demonstrates that 31P MRSI can be used to assess metabolic changes in humans during liver regeneration, and may be useful for assessing derangement of the regenerative process or guiding adjuvant chemotherapies. Magn Reson Med 54:264–271, 2005. © 2005 Wiley‐Liss, Inc.
Brain γ‐aminobutyric acid measurement by proton double‐quantum filtering with selective J rewinding
Authors: Choi Changho , Coupland Nicholas J. , Hanstock Christopher C. , Ogilvie Catherine J. , Higgins Andrea C. M. , Gheorghiu Dan , Allen Peter S.
Published: July 2005

An optimized single‐shot proton double‐quantum (DQ) filter for the quantification of γ‐aminobutyric acid (GABA) levels in human brain is reported. It is demonstrated that creation of DQ coherences following dual‐resonance‐selective refocusing gives a theoretical editing efficiency of 50% for the detection of the GABA resonance at 3.01 ppm. The sequence times are optimized with both numerical and experimental analyses of the editing performance, giving an experimental editing efficiency of 42%. It is acknowledged that homocarnosine is partially coedited, leading to a 20% contribution to the edited signal; however, macromolecule contamination is negligible in vivo under these experimental conditions. The GABA concentration in human prefrontal cortex is estimated to be 0.8 ± 0.1 μmol/g (mean ± SD, n = 6), with reference to the internal standard creatine at 9 μmol/g. Magn Reson Med 54:272–279, 2005. © 2005 Wiley‐Liss, Inc.
On the cause of spatial displacement of long T1 species in segmented inversion recovery prepared imaging
Authors: Goldfarb James W. , Arnold Sheeba , Schapiro William , Reichek Nathaniel
Published: July 2005

Using inversion recovery steady‐state free precession segmented k‐space imaging for the detection of myocardial infarction, we noticed that some structures appeared in the wrong locations of the image. In this work, the spatial displacement is demonstrated and explained from both theoretical and experimental points of view. The effect is due to a change in phase from segment to segment of the detected magnetization from species with long T1's such as cysts, fluid collections, and cerebrospinal fluid. Depending on the number of k‐space segments and view ordering, structures can be replicated throughout the image or displaced by half of the phase‐encoding field of view. Magn Reson Med 54:481–485, 2005. © 2005 Wiley‐Liss, Inc.
Diffusion tensor imaging using partial Fourier STEAM MRI with projection onto convex subsets reconstruction
Authors: Rieseberg Susanne , Merboldt Klaus‐Dietmar , Küntzel Matthias , Frahm Jens
Published: July 2005

Diffusion‐weighted single‐shot STEAM MRI allows for diffusion mapping of the human brain without sensitivity to resonance offset effects. In order to compensate for its inherently lower SNR and speed than echo‐planar imaging, this work describes the use of partial Fourier encoding in combination with image reconstruction by the projection onto convex subsets algorithm. The method overcomes phase distortions in diffusion‐weighted partial Fourier acquisitions that disturb the conjugate complex symmetry of k‐space and preclude the use of respective reconstruction techniques. In comparison with full Fourier encoding and a static flip angle for the STEAM readout pulses, experimental results at 2.9 T demonstrate a gain in relative SNR per unit time by 20% for 5/8 phase encoding with optimized variable flip angles. Simultaneously, the imaging time is reduced from about 670 ms (80 echoes) to 440 ms (50 echoes). Current implementations at 2 × 2 mm2 in‐plane resolution comprise a protocol for clinical anisotropy studies (12 diffusion‐encoding gradient directions at 1000 s mm−2) covering 18 sections of 4‐mm thickness within a measurement time of 8.5 min (5 averages) and a version optimized for fiber tracking using 24 gradient directions and 38 sections of 2‐mm thickness yielding a measurement time of 29.5 min (4 averages). Magn Reson Med 54:486–490, 2005. © 2005 Wiley‐Liss, Inc.
Contrast‐enhanced 4D radial coronary artery imaging at 3.0 T within a single breath‐hold
Authors: Bi Xiaoming , Park Jaeseok , Larson Andrew C. , Zhang Qiang , Simonetti Orlando , Li Debiao
Published: July 2005

Coronary magnetic resonance angiography data are usually acquired during mid‐diastole of each heartbeat to minimize cardiac motion related artifacts. The proper trigger delay time, which may vary widely among subjects, must be determined individually for each subject before data acquisition to achieve optimal image quality. These complications could be resolved by acquiring contiguous cardiac phase images through the cardiac cycle. In this study, we used a radial sampling technique to acquire 3D cine coronary artery images at 3 T within a single breath‐hold. An extravascular, paramagnetic contrast agent was i.v. administered to improve the blood signal intensity. Relatively high temporal resolution and spatial resolution were achieved simultaneously with radial sampling, parallel data acquisition, and interleaved sliding window image reconstruction. Volunteer studies demonstrate the feasibility of this technique in acquiring 4D coronary artery images and the flexibility in postprocessing of 3D image sets. Magn Reson Med 54:470–475, 2005. © 2005 Wiley‐Liss, Inc.
Magnetic resonance imaging and mathematical modeling of progressive formalin fixation of the human brain
Authors: Yong‐Hing Charlotte J. , Obenaus Andre , Stryker Rodrick , Tong Karen , Sarty Gordon E.
Published: July 2005

The temporal magnetic resonance (MR) appearance of human brain tissue during formalin fixation was measured and modeled using a diffusion mathematical model of formalin fixation. Coronal MR images of three human brains before formalin fixation and at multiple time points thereafter were acquired. T1 relaxation, T2 relaxation, water apparent diffusion coefficient (ADC), and proton density (PD) maps were calculated. The size of a light “formalin band” region, visible in T1 weighted images, was compared to a mathematical model of diffusive mass transfer of formalin into the brain. T1 relaxation, T2 relaxation, and PD all decreased, in both gray and white matter, as formalin fixation progressed. The ADC remained more or less constant. The location of the inner boundary of the formalin band followed a time course consistent with the steepest formalin concentration gradient in the mathematical model. Based on the diffusion model, the brain is not completely saturated in formalin until after 14.8 weeks of formalin immersion and, based on the observed changes in T1, T2, and PD, fixation is not complete until after 5.4 weeks. During fixation, the ongoing attenuation of T1 relaxation, T2 relaxation, and PD must be taken into consideration when performing postmortem MRI studies. Magn Reson Med 54:324–332, 2005. © 2005 Wiley‐Liss, Inc.
Single‐shot 3D imaging techniques improve arterial spin labeling perfusion measurements
Authors: Günther Matthias , Oshio Koichi , Feinberg David A.
Published: July 2005

Arterial spin labeling (ASL) can be used to measure perfusion without the use of contrast agents. Due to the small volume fraction of blood vessels compared to tissue in the human brain (typ. 3–5%) ASL techniques have an intrinsically low signal‐to‐noise ratio (SNR). In this publication, evidence is presented that the SNR can be improved by using arterial spin labeling in combination with single‐shot 3D readout techniques. Specifically, a single‐shot 3D‐GRASE sequence is presented, which yields a 2.8‐fold increase in SNR compared to 2D EPI at the same nominal resolution. Up to 18 slices can be acquired in 2 min with an SNR of 10 or more for gray matter perfusion. A method is proposed to increase the reliability of perfusion quantification using QUIPSS II derivates by acquiring low‐resolution maps of the bolus arrival time, which allows differentiation between lack of perfusion and delayed arrival of the labeled blood. For arterial spin labeling, single‐shot 3D imaging techniques are optimal in terms of efficiency and might prove beneficial to improve reliability of perfusion quantitation in a clinical setup. Magn Reson Med 54:491–498, 2005. © 2005 Wiley‐Liss, Inc.