bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental toxic effects ofN‐ethyl‐2‐pyrrolidone administered orally to rats
Authors: Saillenfait A. M. , Gallissot F. , Sabaté J. P. 
Published: March 2007

AbstractThe developmental toxicity ofN‐ethyl‐2‐pyrrolidone (NEP) was studied in Sprague‐Dawley rats after oral administration. Pregnant rats were given NEP at doses of 0 (distilled water), 50, 250, 500 and 750 mg kg−1day−1, by gavage (5 ml kg−1), on gestational days (GD) 6–20. Maternal toxicity, as evidenced by reduction in body weight gain and food consumption, was observed in all NEP groups at the beginning of treatment (GD 6–9). The incidence of resorptions was significantly increased at 500 mg kg−1day−1, and reached 83% at 750 mg kg−1day−1. There was a dose‐related decrease in fetal weight, which was significantly lower than control at 250 mg kg−1day−1and higher doses. The incidence of malformed fetuses per litter and the number of litters with malformed fetuses were significantly increased at 500 and 750 mg kg−1day−1. Malformations mainly consisted of edema, anal atresia with absent tail, cardiovascular defects and fused cervical arches. Ossification of skull bones and sternebrae was significantly reduced at 500 and 750 mg kg−1day−1. The incidence of supernumerary ribs was significantly elevated at 250 mg kg−1day−1and higher doses. In conclusion, NEP administered by gavage is embryotoxic and teratogenic at maternal toxic doses. Copyright © 2007 John Wiley & Sons, Ltd.
Study on the in vitro effect of zearalenone and α‐zearalenol on boar sperm–zona pellucida interaction by hemizona assay application
Authors: Tsakmakidis I. A. , Lymberopoulos A. G. , Vainas E. , Boscos C. M. , Kyriakis S. C. , Alexopoulos C. 
Published: March 2007

AbstractThe mycotoxin zearalenone (zen) impairs fertility in farm animals. The aim of the present study was to investigate the effect of zearalenone and its major metabolite (α‐zearalenol) on boar semen binding capacity, under in vitro conditions. Extended boar semen was exposed to three different concentrations of zen and α‐zen (40, 60 and 80 µg ml−1 of semen) for 1 h. Afterwards, the semen was washed and incubated with homologous oocyte hemizona for 4 h. A significant decrease (P < 0.001) in the number of tightly attached spermatozoa on the hemizona was obtained at concentrations of 60 µg ml−1 and 80 µg ml−1 of zen and α‐zen. In conclusion, zen and α‐zen affected the sperm–zona interaction by reducing the ability of boar spermatozoa to bind to the zona pellucida. Copyright © 2007 John Wiley & Sons, Ltd.
Reactivation of organophosphate‐inhibited human AChE by combinations of obidoxime and HI 6 in vitro
Authors: Worek F. , Aurbek N. , Thiermann H. 
Published: March 2007

AbstractHighly toxic organophosphorus‐type (OP) chemical warfare agents (nerve agents) and OP pesticides may be used by terrorists and during military conflicts emphasizing the necessity for the development of effective medical countermeasures. The standard treatment with atropine and acetylcholinesterase (AChE) reactivators (oximes) is considered to be ineffective with certain nerve agents due to low oxime efficacy. Despite research over decades none of the oximes has turned out to be a broad spectrum reactivator to cover the whole range of potential threat agents. The prospective oxime HI 6 is a weak reactivator of tabun‐ and pesticide‐inhibited AChE, while the established oxime obidoxime mainly lacks efficacy with cyclosarin‐inhibited enzyme. In order to investigate the feasibility of combining obidoxime and HI 6, human AChE inhibited by sarin, cyclosarin, VX, tabun and paraoxon was reactivated by these oximes either alone or in combination. Two major findings of this study were that a combination of HI 6 and obidoxime did not impair reactivation, compared with HI 6 or obidoxime alone, but broadened the spectrum compared with the individual oximes. By using different oxime concentrations a combination of oxime doses may be suggested which could be an alternative to individual obidoxime or HI 6 autoinjectors. Copyright © 2007 John Wiley & Sons, Ltd.
Peripheral nerve regeneration through the space formed by a chitosan gel sponge
Authors: Ishikawa N. , Suzuki Y. , Ohta M. , Cho H. , Suzuki S. , Dezawa M. , Ide C. 
Published: March 2007

AbstractThe clinical treatment of traumatized peripheral nerves often requires grafting of autologous cutaneous nerves. However, there are drawbacks in sacrificing healthy nerves and tissue scarring. In this study, an artificial material, freeze‐dried chitosan gel sponge, was examined as a scaffold for nerve regeneration in rats. An 8‐mm gap was made by removing a segment of the sciatic nerve, and the distal and proximal stumps were sandwiched by chitosan gel sponge. Rats were killed at 4, 7, 14, and 28 days, and 2 and 4 months after the operation and histological and morphometric evaluations were performed. Regenerating axons were observed at 4 days after the operation. Regenerating nerves extended the distal stump at 14 days after surgery. By electron microscopy, numerous macrophages appeared to phagocyte chitosan, and made a dense cell layer on the chitosan. Regenerating axons did not touch the chitosan, and extended through the space surrounded by macrophage‐stacked chitosan. Regenerating nerves were well‐myelinated 2 months after surgery. Regenerating nerves were on average 2.45 and 2.75 μm in diameter at 2 and 4 months, respectively, after surgery. These results indicate that the chitosan gel sponge sandwich might be suitable as a graft for peripheral nerve regeneration. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Biological stability of polyurethane modified with covalent attachment of di‐tert‐butyl‐phenol
Authors: Stachelek Stanley J. , Alferiev Ivan , Fulmer James , Ischiropoulos Harry , Levy Robert J. 
Published: March 2007

AbstractPolyurethane cardiovascular implants are subject to oxidation initiated surface degradation, which is mediated by monocyte‐derived macrophages (MDM); this often leads to surface cracking and device failure. The present studies examined the hypothesis that covalently attaching antioxidant, di‐tert‐butylphenol (DBP), to the urethane nitrogens of a polyether polyurethane (PU) via bromo‐alkylation reactions could prevent this problem. PU was configured with two dosages of DBP, 0.14 mM DBP/g PU of DBP (PU‐DBP) and a more highly modified (HM) 0.40 mM DBP/g PU (PU‐DBP‐HM). THP‐1 cells, a human MDM cell line, stimulated with phorbol ester and seeded on PU, PU‐DBP, and PU‐DBP‐HM films were assessed for reactive oxygen species (ROS) production via a fluorescent based dihydrorhodamine‐123 assay. Results from these studies showed a significant dose‐dependent reduction of ROS levels for THP‐1 cells seeded on PU‐DBP versus unmodified PU. PU, PU‐DBP, or PU‐DBP‐HM films were implanted into subdermal pouches of Sprague–Dawley rats. Films were explanted after 10 weeks and assessed for oxidative degradation via light and scanning electron microscopy (SEM) and Fourier transformation infrared spectroscopy (FTIR). Light microscopy showed extensive surface cracking, which was confirmed via SEM, on unmodified PU surfaces that was absent in both PU‐DBP and PU‐DBP‐HM explanted films. FTIR analysis showed reduction in oxidation‐induced ether crosslinking that was directly related to DBP dosages. It is concluded that modifying PU with the covalent attachment of an antioxidant confers biodegradation resistance in vivo in a dose dependent manner; this effect is likely due to quenching of the ROS generated by the adherent macrophages. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Hypoxia regulates PGE2 release and EP1 receptor expression in osteoblastic cells
Authors: Lee Christina M. , Genetos Damian C. , You Zongbing , Yellowley Clare E. 
Published: March 2007

AbstractChanges in regional O2 tension that occur during fracture and skeletal unloading may stimulate local bone cell activity and ultimately regulate bone maintenance and repair. The mechanisms by which bone cells sense and respond to changes in O2 tension are unclear. In this study we investigated the effects of low O2 on activation of the hypoxia response element (HRE), prostaglandin E2 (PGE2) production, PGE2 receptor (EP) expression and proliferation in MC3T3‐E1 osteoblastic cells. Cells were cultured for up to 72 h in 2% O2 (considered hypoxic), 5% O2 (in the range of normal O2 tension in vivo) or 21% O2 (commonly used for cell culture). Cells cultured in 2% O2 showed activation of the HRE, increased PGE2 release, increased EP1 expression, and reduced cell proliferation compared to cells grown at 21% O2. Similarly, cells cultured in 5% O2 showed increased expression of EP1 and a trend toward a decrease in proliferation, but no activation of the HRE or increase in PGE2 levels. Expression of EP2, EP3 and EP4 were not affected by O2 tension. The differences in EP receptor profile observed in cells grown at 5% compared to 21% O2 suggest that bone cell phenotype may be altered under routine cell culture conditions. Furthermore, our data suggest that hypoxia‐dependent PGE2 production and EP1 expression in bone cells may play a role in bone remodeling and repair in regions of compromised or damaged bone, where O2 tension is low. J. Cell. Physiol. 212: 182–188, 2007. © 2007 Wiley‐Liss, Inc.
MR findings in diffuse renal parenchymal disease
Authors: Kettritz Ute , Semelka Richard C. , Brown Elizabeth D. , Sharp Tonya J. , Lawing William L. , Colindres Romulo E. 
Published: March 2007

AbstractThis study evaluates the MR appearance of the kidney in diffuse renal parenchymal diseases, using precontrast, and immediate and delayed postgadolinium chelate (Gd), spoiled gradient echo (SGE), and pre‐ and post‐Gd, T1‐weighted, fat‐suppressed spin‐echo MR images to determine if characteristic findings exist for various types of renal disease. One hundred twenty one patients with renal disease underwent MRI. Underlying diagnoses included: (a) glomerular disease (GD), (b) tubulointerstitial disease (TID), (c) microvascular disease (MVD), (d) ischemic nephropathy (INP), (e) obstructive nephropathy (ON), (f) infectious renal disease (IRD), (g) sickle cell disease (SCD), (h) renal cortical necrosis (CN), and (i) renal insufficiency of unknown etiology (UE). MR examinations of 22 patients with normal kidneys (NK) were evaluated as a control group. The presence of corticomedullary differentiation (CMD) demonstrated strong inverse correlation with serum creatinine concentration (SCr) (r=− .568, P <.001). Mean thickness of the renal cortex was 8.4 and 7.8 mm in patients with NK and Gd, respectively. The mean cortical thickness in patients with MVD, TID/Chemo, INP, and ON was 5.2, 5.6, 5.5, and 4.3 mm, respectively, significantly thinner than the renal cortex in the NK and GD groups (P <.01). Irregularity of the renal cortex was more frequent in MVD (60.9%), IRD (62.5%), ON (55.6%), and TID/other (53.8%) than in GD (3.8%) and NK (0%) (P < .01). Diffuse high SI of the entire medulla on delayed postcontrast images was observed in 25(20.7%) of the patients with renal disease and none of the NK group. Although no pathognomonic features were found, certain findings were observed that may correlate with the etiology of the kidney disease and, therefore, assist in the differential diagnosis of renal parenchymal disease.
Use of proton MR spectroscopy and MR imaging to assess obesity
Authors: Barac‐Nieto Mario , Gupta Raj K. 
Published: March 2007

AbstractWe used 1H MR spectroscopy and MR imaging at 9.4‐T to quantify and localize fat and water in the abdominal regions of 12 lean, normal, and obese mice. The D2O dilution method which measures also the equilibrium plasma D2O concentration by 2H MR spectroscopy was used to quantify body water and fat. In obese mice, the intensity of the fat 1H resonance was about 120% that of the water 1H resonance, about threefold higher than its value (about 45%) in normal mice. In lean mice, the fat/water intensity ratio was about 1:4, about half that in normal mice. Total body water was similar in obese and normal mice (19.9 ± 1.5 and 18.7 ± 1.3 mL) despite their very different body weights (50.1 ± 3.1 g and 30.2 ± 3.1 g, respectively), but slightly lower in lean mice (14.8 ± 1.2 mL water; 22.1 g ± 2.0g weight). Selective methylene‐proton images showed marked accumulation of fat in the abdomen and the retroperitoneal and subcutaneous spaces of obese mice. Selective water‐proton images allowed clear resolution of the renal cortex, medulla, papilla, and urinary pelvis. The readily measurable resonance intensity ratio of abdominal fat to water is a sensitive index by which to characterize obesity.
Is there a hazard to health by mercury exposure from amalgam due to MRI?
Authors: Müller‐Miny H. , Erber D. , Möller H. , Müller‐Miny B. , Bongartz G. 
Published: March 2007

AbstractThe local magnetic fields from computer monitors are well known. Recently a hypothesis was published that these magnetic fields may lead to a 400% increase of mercury dissolution from dental amalgam fillings. In MRI the exposure to the magnetic field exceeds by far the exposure from computer monitors. Therefore, this study examined the amalgam‐related mercury release for typical MRI conditions, separated for both the static and the variable magnetic fields in a 1.5 T MR‐unit. First, 20 dental cavities were filled with a non‐gamma‐2 amalgam, and the mercury release was measured for 14 days in a non‐magnetic environment. Second, one half of the specimens were exposed to a static magnetic field for 24 hours (group A), while the other specimens were exposed to a repetitive gradient echo sequence for 60 minutes (group B). In both experiments there was no significant increase in mercury release due to MRI. This in vitro study demonstrated no evidence of an elevated mercury dissolution from a nongamma‐2 amalgam during magnetic field exposure by MRI; therefore, there is no increased risk to health.
Magnetic resonance imaging of patients wearing a surgical traction halo
Authors: Hua Jianmin , Fox Richard A. 
Published: March 2007

AbstractMagnetic resonance images of patients wearing a surgical halo may have unacceptable artifacts if the halo has a conductive loop structure. This study shows that the observed artifacts are predominantly due to eddy currents generated in the halo by switching field gradients, and that these artifacts can be substantially reduced by adjusting the phase encoding direction in MRI sequences so that it is parallel to the axis of the halo.
Contrast enhancement in experimental radiation‐induced liver injury: Comparison of hepatocellular and reticuloendothelial particulate contrast agents
Authors: Stiskal Michael , Schwickert Heidi C. , Demsar Franci , Roberts Timothy P. L. , Szolar Dieter , Weissleder Ralph , Brasch Robert C. 
Published: March 2007

AbstractWe compared the liver enhancement of two super‐paramagnetic agents, polycrystalline iron oxide nano‐particles (PION) and PION coated with asialofetuin (ASF), in an experimental model of focal radiation‐induced hepatitis. PION, a reticuloendothelial system‐directed agent, and PION‐ASF, a hepatocellular‐directed agent, were compared for time‐dependent liver enhancement in an experimental model of radiation‐induced liver injury. Using the reticuloendothelial system (RES)‐directed PION, the normal, nonirradiated portion of the liver decreased in signal intensity (SI) with a mean negative enhancement of –66% ± 4, whereas the irradiated portion (60 Gy, 3 days before imaging) of the liver decreased in SI by –24% ± 2, significantly less (P < .05). SI changes in irradiated liver tissue using PION were dose‐dependent, being more pronounced with lower radiation exposure. The difference in SI changes induced by PION‐ASF between irradiated and nonirradiated liver was not statistically different, but SI decreased with a mean negative enhancement of –80% ± 2. The RES‐directed PION is more sensitive for the detection of radiation‐induced hepatitis than is the hepatocyte‐directed PION‐ASF. The insensitivity of PION‐ASF enhancement for diffuse liver injury may be clinically advantageous for detecting focal lesions in the presence of diffuse hepatic injury.
MR hysterosalpingography in a rabbit model
Authors: Lee Fred T. , Grist Thomas M. , Nelson Kathleen G. , Chosy Susan G. , Rappe Alan H. , Shapiro Sander S. , Kelcz Frederick 
Published: March 2007

AbstractOur objective was to evaluate the efficacy of MR imaging as compared with conventional hysterosalpingography (HSG) for the detection of fallopian tube patency after uterine injection of contrast material. Rabbit uterine horns (n = 18) were catheterized transvaginally. Five fallopian tubes were ligated and 11 were left unaltered. T1‐weighted gradient‐echo MR images were obtained before, during, and after injection of 1.0–3.0 mL of a dilute gadolinium‐containing contrast agent. Corresponding conventional studies were performed with an equivalent volume of iohexol. Images were evaluated by two blinded readers. Observers agreed in all cases on the presence (n = 11) or absence (n = 5) of peritoneal spill with conventional HSG. Interpretation of MR HSG concurred with conventional HSG in 14 of 16 cases for each observer (P > .05). Reasons for misdiagnosis included small amounts of spill (n = 2), artifact (n = 1), and subtle spill between bowel loops (n = 1). Sensitivity and specificity for MR HSG were 95.5% and 70%, respectively, for the diagnosis of tubal patency/occlusions. No statistical difference was found between MR HSG and conventional HSG for the diagnosis of fallopian tube patency/obstruction. Potential advantages of MR HSG include no ionizing radiation, potentially diminished local contrast toxicity, superior visualization of uterine fibroids and endometriosis, and visualization of ovaries. We conclude that this technique warrants further study, including the use of a primate model to better simulate human anatomy.
Dynamic contrast‐enhanced MR imaging of musculoskeletal tumors: Basic principles and clinical applications
Authors: Verstraete Koenraad L. , Woude Henk‐Jan Van der , Hogendoorn Pancras C. W. , De Deene Yves , Kunnen Marc , Bloem Johannes L. 
Published: March 2007

AbstractThe purpose of this article is to review the basic principles and clinical applications of dynamic contrast‐enhanced MRI in the musculoskeletal system. This method of physiologic imaging provides clinically useful information by depicting tissue vascularization and perfusion, capillary permeability, and composition of the interstitial space. Different imaging, evaluation, and postprocessing techniques are described. The most important applications in the musculoskeletal system are identification of areas of viable tumor for biopsy, tissue characterization, and monitoring of preoperative chemotherapy. Practical guidelines for performing a dynamic contrast‐enhanced MR examination are proposed.
Evaluation of frog gastric mucous secretion by 7T magnetic resonance imaging
Authors: Sbarbati Andrea , Leclercq Françoise , Zancanaro Carlo , Guerrini Uliano , Antonakis Kostas , Osculati Francesco 
Published: March 2007

AbstractThis work describes a new method to evaluate the action of drugs on gastric mucus secretion by 7 T MRI. A polyethylene probe was inserted into the stomach of frogs, a water washing cycle was performed, air was inflated into the stomach, and the probe was removed. Drugs were administered topically by mixing them with the water used for stomach washing, and a series of images was collected. In untreated animals, a mucous layer emitting a high intensity signal covered the gastric mucosa. Atropine administration strongly reduced the mucous layer thickness. After pilocarpine administration, MRI images showed that the mucous layer was thicker than in controls. After metacholine administration, the thickness of the mucous layer was increased in comparison with both controls and pilocarpine‐treated animals, in accord with the expected drug‐induced increase of mucous secretion. Quantitative analysis of the mucous layer thickness on MRI images confirmed the above findings. In conclusion, these results indicate that MRI at 7 T is a sensitive in vivo screening test to evaluate the effect of drugs on gastric mucus secretion in absence of surgical manipulation, thereby enabling morphofunctional studies that cannot be performed by conventional methods.
Adaptive filtering for high resolution magnetic resonance images
Authors: Ying Kui , Clymer Bradley D. , Schmalbrock Petra 
Published: March 2007

AbstractWe present a study of least mean square (LMS) based adaptive filters for high resolution magnetic resonance (MR) images to improve signal‐to‐noise ratio (SNR) while maintaining sharp edges. Five variations of a new technique that senses the type of noise or the presence of an edge in the filtering window, called adaptive filtering with noise estimation (AFEN) are presented and compared with the basic two‐dimensional LMS (TDLMS) algorithm, adaptive filtering with a mean estimator (AFLME), a two‐dimensional averaged LMS (TDALMS) algorithm, and a two‐dimensional median weighted LMS (TDMLMS) algorithm. Although TDLMS, TDALMS, and TDMLMS filters give better SNR improvement when applied uniformly to an image, they significantly blur edges. The AFLME and AFEN filters both show approximately a factor of 2 SNR improvement with much better retention of edges, with AFEN showing slightly better performance for both SNR and edge sharpness in phantom and in vivo inner ear images.
Enhancement efficacy of magnetic starch microspheres (MSM) in conventional spin‐echo and turbo spin‐echo sequences at 0.5 T and 1.5 T
Authors: Kreft Burkhard , Block Wolfgang , Mühlhäuser Jost , Träber Frank , Öksenda Audun , Schild Hans 
Published: March 2007

AbstractThe efficacy of the superparamagnetic contrast agent magnetic starch microspheres (MSM) was evaluated in vitro by NMR relaxometry and in vivo by MR imaging using T2‐weighted spin‐echo (SE) and turbo spin‐echo (TSE) sequences at 0.5 T and 1.5 T in 60 normal rats who received MSM in doses of 10–50 μmol/kg. MR imaging was performed using T2‐weighted SE and TSE sequences. The relaxation rates 1/T1 and 1/T2 for liver and spleen increased linearly with MSM concentrations up to 30 μmol/kg body weight, and approached almost constant levels for higher doses. The slopes in the linear part of the 1/T2 diagram were 0.62 Hz ± 0.03 for the liver and 0.51 Hz ± 0.06 × kg/μmol for the spleen. On all T2‐weighted sequences at 0.5 T and 1.5 T, liver signal‐to‐noise ratio (SNR) decreased by a factor of 2‐3 already at the lowest dose of 10 μmol/kg. SNR values of TSE sequences exceeded values for SE sequences by 50–80%. The SNR decrease was not significantly different between SE and TSE sequences. Our results show that MSM is well suited as a T2 contrast agent at both magnetic field strengths when using conventional SE and fast TSE sequences.
On the stationary states in gradient echo imaging
Authors: Sobol Wlad T. , Gauntt David M. 
Published: March 2007

AbstractA formalism is presented that concisely describes the magnetization of a sample subjected to a periodic series of RF pulses. In this formalism, the steady state of the magnetization is shown to be a sum of magnetic substates, each with unique contrast characteristics. When more than one substate contributes to a given image, the substates interfere with each other, producing ghosts and other artifacts. Properly designed gradient protocols can image single substates, producing ghost‐free images. The contrast of the image depends largely on the choice of the imaged substate. Analytic solutions for unspoiled, RF spoiled, and gradient spoiled magnetizations are presented.