bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural and regulatory macromolecules in sex differentiation of gonads
Authors: Pelliniemi Lauri J. , Fröjdman Kim 
Published: August 2002

AbstractThe manifestations of sex determination were studied in vivo by detection and localization of structural and regulatory macromolecules (type IV collagen α1, α2, α3, α4, and α5; laminin α5, β1, and β2; cytokeratins 18 and 19, desmin, vimentin; integrin α6;anti‐Müllerian hormone (AMH); and SOX9 in developing male and female gonads by light and electron microscopy, immunocytochemistry, and protein analysis. The goal has been to find sex‐related differences and on this basis to offer new molecules to be tested further for a possible role in sex determination. Specific antibodies for each molecule or for a defined subchain were used to allow tentative correlation with specific genes. Sex‐dependent differences in timing and localization were found in laminin α5; collagen, α3, α4, and α5; cytokeratin 19; AMH; and SOX9. On this basis we hypothesize that the transcription factors for the mentioned structural proteins must be directly or indirectly involved in the regulatory chain of gonadal sex differentiation. Especially promising is the finding in the rat that laminin α5 chain disappears from the basement membrane of embryonic testicular cords (Sertoli cells) when AMH secretion by Sertoli cells starts, and that the same chain reappears as the AMH disappears two weeks after birth. Via AMH as an intermediary factor, we now have for the first time a putative cascade of regulatory molecules from SRY, SF1, and SOX9 to a component of a structural protein (laminin α5 chain) which directly participates in the formation of the basement membrane of the testicular cords.J. Exp. Zool. 290:523–528, 2001. © 2001 Wiley‐Liss, Inc.
Intrinsically knotted graphs
Authors: Foisy Joel 
Published: August 2002

AbstractIn 1983, Conway and Gordon [J Graph Theory 7 (1983), 445–453] showed that every (tame) spatial embedding of K7, the complete graph on 7 vertices, contains a knotted cycle. In this paper, we adapt the methods of Conway and Gordon to show that K3,3,1,1 contains a knotted cycle in every spatial embedding. In the process, we establish that if a graph satisfies a certain linking condition for every spatial embedding, then the graph must have a knotted cycle in every spatial embedding. © 2002 Wiley Periodicals, Inc. J Graph Theory 39: 178–187, 2002; DOI 10.1002/jgt.10017
Functional‐adaptive analysis of the hindlimb anatomy of extant marsupials and the paleobiology of the Paleocene marsupials Mayulestes ferox and Pucadelphys andinus
Authors: Argot Christine 
Published: August 2002

AbstractThis article analyzes the adaptations of the hindlimb of two Early Paleocene marsupials, Mayulestes ferox and Pucadelphys andinus. This analysis is based on detailed comparisons with various extant marsupials, both South American and Australian. In the case of the South American opossums, original myological data were collected and osteological–myological associations were related to their locomotor behavior. The use of Australian genera helped to improve the appraisal of the locomotory habits of the fossil taxa. Several features are indicative of the ability of Mayulestes to climb or walk on uneven surfaces (e.g., very mobile hip joint, astragalocalcaneal joint pattern), and some other features emphasize a relative agility (e.g., strongly everted iliac blades, morphology of the distal epiphysis of the femur, medially stabilized cruroastragalar joint). Pucadelphys exhibits a hindlimb relatively similar morphologically to that of Mayulestes, but with features indicating slightly increased agility and a terrestrial component that is more emphasized than in Mayulestes. The Tiupampa fossils were therefore more agile than most living didelphids and resembled the condition observed in living dasyurids more. These conclusions complement a previous study performed on the forelimb of these fossils. J. Morphol. 253:76–108, 2002. © 2002 Wiley‐Liss, Inc.
FLAIR histogram segmentation for measurement of leukoaraiosis volume
Authors: Jack Clifford R. , O'Brien Peter C. , Rettman Daniel W. , Shiung Maria M. , Xu Yuecheng , Muthupillai Raja , Manduca Armando , Avula Ramesh , Erickson Bradley J. 
Published: August 2002

AbstractThe purposes of this study were to develop a method to measure brain and white matter hyperintensity (leukoaraiosis) volume that is based on the segmentation of the intensity histogram of fluid‐attenuated inversion recovery (FLAIR) images and to assess the accuracy and reproducibility of the method. Whole‐head synthetic image phantoms with manually introduced leukoaraiosis lesions of varying severity were constructed. These synthetic image phantom sets incorporated image contrast and anatomic features that mimicked leukoaraiosis found in real life. One set of synthetic image phantoms was used to develop the segmentation algorithm (FLAIR‐histoseg). A second set was used to measure its accuracy. Test retest reproducibility was assessed in 10 elderly volunteers who were imaged twice. The mean absolute error of the FLAIR‐histoseg method was 6.6% for measurement of leukoaraiosis volume and 1.4% for brain volume. The mean test retest coefficient of variation was 1.4% for leukoaraiosis volume and 0.3% for brain volume. We conclude that the FLAIR‐histoseg method is an accurate and reproducible method for measuring leukoaraiosis and whole‐brain volume in elderly subjects. J. Magn. Reson. Imaging 2001;14:668–676. © 2001 Wiley‐Liss, Inc.
Effect of acquisition parameters on the accuracy of velocity encoded cine magnetic resonance imaging blood flow measurements
Authors: Greil Gerald , Geva Tal , Maier Stephan E. , Powell Andrew J. 
Published: August 2002

AbstractPurposeTo investigate the effect of acquisition parameters on the accuracy of 2D velocity encoded cine magnetic resonance imaging (VEC MRI) flow measurements.Materials and MethodsUsing a pulsatile flow phantom, through‐plane flow measurements were performed on a flexible vessel made of polyvinyl alcohol cryogel (PVA), a material that mimics the MR signal and biomechanical properties of aortic tissue.ResultsRepeated VEC MRI flow measurements (N = 20) under baseline conditions yielded an error of 0.8 ± 1.5%. Slice thickness, angle between flow and velocity encoding directions, spatial resolution, velocity encoding range, and radio frequency (RF) flip angles were varied over a clinically relevant range. Spatial resolution had the greatest impact on accuracy, with a 9% overestimation of flow at 16 pixels per vessel cross‐section.ConclusionVEC MRI proved to be an accurate and reproducible technique for pulsatile flow measurements over the range of acquisition parameters examined as long as sufficient spatial resolution was prescribed. J. Magn. Reson. Imaging 2002;15:47–54. © 2002 Wiley‐Liss, Inc.
Magnetic resonance imaging and permanent cosmetics (tattoos): Survey of complications and adverse events
Authors: Tope Whitney D. , Shellock Frank G. 
Published: August 2002

AbstractPurposeTo use a survey to determine the incidence of complications and adverse events in individuals with permanent cosmetics (e.g., tattooed eyeliner, eyebrows, lips, cheeks, etc.) who underwent magnetic resonance (MR) imaging.Materials and MethodsA questionnaire was distributed to clients of cosmetic tattoo technicians. This survey asked study subjects for demographic data, information about their tattoos, and for their experiences during MR imaging procedures.ResultsData obtained from 1032 surveys were tabulated. One hundred thirty‐five (13.1%) study subjects underwent MR imaging after having permanent cosmetics applied. Of these, only two individuals (1.5%) experienced problems associated with MR imaging. One subject reported a sensation of “slight tingling” and the other subject reported a sensation of “burning”; both sensations were transient in nature.ConclusionBased on these findings and information in the peer‐reviewed literature, it appears that MR imaging may be performed in patients with permanent cosmetics without any serious soft tissue reactions or adverse events. Therefore, the presence of permanent cosmetics should not prevent a patient from undergoing MR imaging. J. Magn. Reson. Imaging 2002;15:180–184. © 2002 Wiley‐Liss, Inc.
The reproducibility and sensitivity of brain tissue volume measurements derived from an SPM‐based segmentation methodology
Authors: Chard Declan T. , Parker Geoffrey J.M. , Griffin Colette M.B. , Thompson Alan J. , Miller David H. 
Published: August 2002

AbstractPurposeTo investigate the reproducibility of SPM99‐based whole brain, gray matter, and white matter volume measurements with and without image inhomogeneity correction, subsequently exploring age and gender effects on absolute and fractional (proportional to intra‐cranial) volumes.Materials and MethodsTwenty‐seven control subjects (aged 23.2 to 55.2 years) had three‐dimensional fast spoiled gradient recall scans. Ten subjects were scanned about 197 days later.ResultsCoefficients of variation (CV) for absolute and fractional volumes determined from images processed with inhomogeneity correction ranged from 1.2% to 0.5%. Inhomogeneity correction reduced the CV for all measures except gray matter fractional (GMF) volumes. Significantly lower white matter absolute (WM) and fractional (WMF) volumes, and higher GMF were found in females compared with males, overlying age‐related reductions (in decreasing order of significance) in brain parenchymal fraction, GMF, WMF, brain parenchymal, and gray matter volumes.ConclusionSPM99 segmentations are sufficiently reproducible to detect age and gender effects in limited cohorts J. Magn. Reson. Imaging 2002;15:259–267. © 2002 Wiley‐Liss, Inc.
A new gadolinium‐based contrast agent for magnetic resonance imaging of brain tumors: Kinetic study on a C6 rat glioma model
Authors: Fonchy Emmanuel , Lahrech Hana , François‐Joubert Anne , Dupeyre Roger , Benderbous Soraya , Corot Claire , Farion Régine , Rubin Christophe , Décorps Michel , Rémy Chantal 
Published: August 2002

AbstractT1‐weighted magnetic resonance imaging (MRI) was used to evaluate the potential interest of a new Gd‐based contrast agent, termed P760, to characterize brain tumor heterogeneity and vascularization and to delineate regions containing permeable vessels. The C6 rat glioma model was used as a model of high‐grade glioblastoma. The signal enhancement was measured as a function of time in the vascular compartment and in different regions of interest (ROIs) within the tumor after the injection of 0.02 mmol kg−1 of P760. The results were compared to those obtained after the injection of 0.1 mmol kg−1 of Gd‐DOTA. We showed that P760, in spite of a Gd concentration five times smaller, produces an enhancement in the blood pool similar to that produced by Gd‐DOTA. It was shown that P760 makes possible an excellent delineation of regions containing vessels with a damaged blood‐brain barrier (BBB). Images acquired 5–10 minutes after P760 injection showed the location of permeable vessels more accurately than Gd‐DOTA‐enhanced images. The enhancement produced in the tumor by P760 was, however, less than that produced by Gd‐DOTA. The extravasation and/or diffusion rate of P760 in the interstitial medium were found to be strongly reduced, compared to those found with Gd‐DOTA. This study suggests that the new contrast agent has promising capabilities in clinical imaging of brain tumors. J. Magn. Reson. Imaging 2001;14:97–105. © 2001 Wiley‐Liss, Inc.
In vivo studies of Gd‐DTPA‐monoclonal antibody and gd‐porphyrins: Potential magnetic resonance imaging contrast agents for melanoma
Authors: Shahbazi‐Gahrouei D. , Williams M. , Rizvi S. , Allen B. J. 
Published: August 2002

AbstractNew tumor‐specific contrast agents for clinical imaging and therapy for cancer are required. To this end Gd‐H (Gd‐hematoporphyrin), Gd‐TCP (Gd‐tetra‐carboranylmethoxyphenyl‐porphyrin), Gd‐DTPA‐WM53, and Gd‐DTPA‐9.2.27 were synthesized and administered by systemic injection to nude mice with human melanoma (MM‐138) xenografts. The biodistribution T1 relaxation times and magnetic resonance (MR) image signal enhancement of the contrast agents are presented for the first time and compared for each group of five mice. A change (20%) in T1 relaxation times of water in human melanoma tumor xenografts was revealed 24 hours after injection of the labeled immunoconjugate Gd‐DTPA‐9.2.27. The percent of injected antibody or gadolinium that localized to the tumor was measured by inductively coupled plasma atomic emission spectroscopy (ICP‐AES) to be approximately 35%. A higher concentration of gadolinium was achieved compared with nonspecific compounds, indicating selective delivery of Gd‐DTPA‐9.2.27 to the melanoma xenografts. Porphyrin‐based contrast agents (Gd‐H and Gd‐TCP) also showed significant uptake in melanomas. The uptake of Gd‐TCP by the tumor was sufficient to deliver boron atoms into the tumor, making possible dual use for both MR imaging (MRI) and boron neutron capture therapy (BNCT). The linear relationship found between the paramagnetic contribution to the relaxation rates and contrast agent concentration allows quantitative studies of paramagnetic contrast agent uptake. J. Magn. Reson. Imaging 2001;14:169–174. © 2001 Wiley‐Liss, Inc.
Steady‐state free precession magnetic resonance imaging of the heart: Comparison with segmented k‐space gradient‐echo imaging
Authors: Plein Sven , Bloomer Timothy N. , Ridgway John P. , Jones Tim R. , Bainbridge Gavin J. , Sivananthan Mohan U. 
Published: August 2002

AbstractSteady‐state free precession imaging is a promising technique for cardiac magnetic resonance imaging (MRI), as it provides improved blood/myocardial contrast in shorter acquisition times compared with conventional gradient‐echo acquisition. The better contrast could improve observer agreement and automatic detection of cardiac contours for volumetric assessment of the ventricles, but measurements might differ from those obtained using conventional methods. We compared volumetric measurements, observer variabilities, and automatic contour detection between a steady‐state free precession imaging sequence (BFFE = balanced fast field echo) and segmented k‐space gradient‐echo acquisition (TFE = turbo field echo) in 41 subjects. With BFFE, significantly higher end‐diastolic and end‐systolic volumes and lower wall thickness, ventricular mass, ejection fraction, and wall motion were observed (P < 0.0001), while interobserver variabilities were lower and automatic contour detection of endocardial contours was more successful. We conclude that the improved image quality of BFFE reduces the observer‐dependence of volumetric measurements of the left ventricle (LV) but results in significantly different values in comparison to TFE measurements. J. Magn. Reson. Imaging 2001;14:230–236. © 2001 Wiley‐Liss, Inc.
Effect of eluent on the ionization efficiency of flavonoids by ion spray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization mass spectrometry
Authors: Rauha Jussi‐Pekka , Vuorela Heikki , Kostiainen Risto 
Published: August 2002

AbstractThe effect of nine different eluent compositions on the ionization efficiency of five flavonoids was studied using ion spray (IS), atmospheric pressure chemical ionization (APCI), and the novel atmospheric pressure photoionization (APPI), in positive and negative ion modes. The eluent composition had a great effect on the ionization efficiency, and the optimal ionization conditions were achieved in positive ion IS and APCI using 0.4% formic acid (pH 2.3) as a buffer, and in negative ion IS and APCI using ammonium acetate buffer adjusted to pH 4.0. For APPI work, the eluent of choice appeared to be a mixture of organic solvent and 5 mM aqueous ammonium acetate. The limits of detection (LODs) were determined in scan mode for the analytes by liquid chromatography/mass spectrometry using IS, APCI and APPI interfaces. The results show that negative ion IS with an eluent system consisting of acidic ammonium acetate buffer provides the best conditions for detection of flavonoids in mass spectrometry mode, their LODs being between 0.8 and 13 µM for an injection volume of 20 µl. Copyright © 2001 John Wiley & Sons, Ltd.
Human cytomegalovirus hyperimmune globulin not only neutralizes HCMV infectivity, but also inhibits HCMV‐induced intracellular NF‐κB, Sp1, and PI3‐K signaling pathways
Authors: Andreoni Kenneth A. , Wang Xin , Huang Shu‐Mei , Huang Eng‐Shang 
Published: August 2002

AbstractInhibition of virus‐induced intracellular signaling pathways and viral infectivity are our ultimate goals in the development of effective antiviral agents to control human cytomegalovirus (HCMV) infections. The HCMV hyperimmune globulin may meet such criteria. In a human embryonic lung (HEL) fibroblast culture model, pretreatment of Towne strain HCMV with HCMV hyperimmune globulin was shown to inhibit viral infectivity successfully, as measured by a standard plaque assay. The extracellular viral titers and extracellular viral DNA, as measured by plaque assay and PCR, respectively, were also decreased. In addition, the HCMV hyperimmune globulin prevented HCMV from inducing the intracellular activation of NF‐κB, Sp‐1, and PI3‐K signaling pathways. The PI3‐K pathway was examined by following phosphorylation (activation) of two of its downstream kinases, Akt and p70S6K. HCMV hyperimmune globulin also prevented the production of immediate early, early, and late viral proteins. These studies show that HCMV hyperimmune globulin neutralization of HCMV prevents the earliest known events observed after viral envelope glycoproteins bind their cell membrane receptors, i.e., NF‐κB, Sp‐1 and PI3‐K activation. This suggests that HCMV hyperimmune globulin not only can inhibit viral infectivity, but can also prevent the abnormal cellular signaling that may induce unwanted cellular proliferation or cytokine synthesis. J. Med. Virol. 67:33–40, 2002. © 2002 Wiley‐Liss, Inc.
Simulation of EM wave propagation in magnetoelectric media using TLM
Authors: Christopoulos Christos , Paul John , Thomas David W. P. 
Published: August 2002

AbstractIn this paper, the simulation of general frequency‐dependent magnetoelectric material properties in time‐domain TLM is described. The formulation is developed from Maxwell's equations and the constitutive relations using bilinear 𝒵‐transform methods leading to a general Padé system. The approach is applicable to all frequency‐dependent linear materials including those displaying anisotropic and bianisotropic behaviour. The method is validated by the example of a chiral slab having an analytic solution. Copyright © 2001 John Wiley & Sons, Ltd.
Changes in the cellular distribution of glutamine synthetase in Alzheimer's disease
Authors: Robinson Stephen R. 
Published: August 2002

AbstractThe intracellular localization of glutamine synthetase (GS) in the inferior temporal cortices of non‐demented elderly individuals was compared with that in brains affected by Alzheimer's disease (AD). The present study confirmed previous reports of a general decrease in GS expression in astrocytes and the expression of GS in some neurons. Several new observations were made: the morphology of astrocytes is generally unaffected by the presence of plaques, GS labeling is present in some diffuse plaques and occasional neuritic plaques, whereas the overall density of astrocytes increases 1.4‐fold in AD. In addition, the present study found that the reduction in GS expression is almost entirely due to a loss of GS from perisynaptic regions of the neuropil and from the astrocytic endfeet that normally abut cortical blood vessels. These changes implicate astrocytes in glutamate excitotoxicity and ammonia neurotoxicity. It is suggested that it may be more fruitful to regard AD not as a neuronal disease, but as a disorder of astrocyte‐neuron interactions. © 2001 Wiley‐Liss, Inc.
Differential expression of glutamate dehydrogenase in cultured neurons and astrocytes from mouse cerebellum and cerebral cortex
Authors: Zaganas Ioannis , Waagepetersen Helle S. , Georgopoulos Panagiotis , Sonnewald Ursula , Plaitakis Andreas , Schousboe Arne 
Published: August 2002

AbstractGlutamate dehydrogenase (GDH) specific activities, kinetic properties and allosteric regulation were studied in extracts from cultured neurons and astrocytes prepared from mouse cerebral cortex and cerebellum. Considerable differences were observed in the specific activity of the enzyme among the different cell types with astrocytes expressing the highest GDH activity. This may reflect the functional importance of these cells in glutamate uptake and metabolism. Among the neurons, the glutamatergic cerebellar granule cells showed a GDH specific activity that was 60% higher (P < 0.01) than that of the GABAergic cerebral cortical neurons. Also, the Km for ammonia was 1.7‐fold higher in the cortical neurons than in the other cell types. These findings may reflect a particular need for the glutamatergic granule cells to synthesize glutamate via the GDH pathway. No differences were observed among the different cell types with regard to the allosteric properties of GDH expressed by these cells. © 2001 Wiley‐Liss, Inc.
Elucidation of the quantitative significance of pyruvate carboxylation in cultured cerebellar neurons and astrocytes
Authors: Waagepetersen Helle S. , Qu Hong , Schousboe Arne , Sonnewald Ursula 
Published: August 2002

AbstractPyruvate carboxylation was studied in cerebellar astrocytes and granule neurons. The cells were incubated in medium containing [U‐13C]glucose (2.5 mM) and [U‐13C]lactate (1 mM) and varying amounts of 3‐nitropropionic acid (3‐NPA) plus/minus aspartate. 3‐NPA alone clearly stopped tricarboxylic acid (TCA) cycle activity at the succinate dehydrogenase step in both culture types as evidenced by a buildup of succinate. Labeling of aspartate and glutamate was abolished in neurons in the presence of 3‐NPA. In astrocytes, however, labeled glutamate and glutamine derived from pyruvate carboxylation was detected. Unchanged glucose and lactate metabolism in the absence of a functioning malate aspartate shuttle indicates the importance of the glycerol‐3‐phosphate shuttle in brain cells. To compensate for the loss of oxaloacetate in the presence of 3‐NPA, unlabeled aspartate (0.25 mM) was added. In this case [1,2‐13C] and [3,4‐13C]aspartate were observed in neurons but not in astrocytes. This labeling pattern in aspartate occurs after a full turn of the TCA cycle and thus indicates only partial inhibition by 3‐NPA in the neurons when aspartate is present. In astrocytes, however, aspartate derived from uniformly labeled pyruvate was observed clearly indicating pyruvate carboxylation. The present study has unequivocally demonstrated a quantitatively important pyruvate carboxylation in astrocytes but it was not possible to demonstrate the presence of such carboxylation in neurons. Based on the present results it may be safely concluded that neuronal pyruvate carboxylation is unlikely to be of quantitative significance. © 2001 Wiley‐Liss, Inc.