bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of cryogenic NMR probe technology to long‐range 1H‐15N 2D NMR studies at natural abundance
Authors: Crouch Ronald C. , Llanos William , Mehr Knut G. , Hadden Chad E. , Russell David J. , Martin Gary E. 
Published: August 2002

AbstractThe development of new NMR probe technologies has been an active area of research effort for the past decade. Recently, cryogenically cooled NMR probes have been the subject of considerable interest in the light of the large gains in sensitivity and hence savings in spectrometer time that can be realized by utilizing this technology. With low gamma nuclides, such as 15N, time savings may be less of an issue than the ability to work with available samples rather than having to isolate additional material for analysis. Results of 5–10 Hz optimized CIGAR‐HMBC 1H–15N experiments at natural abundance obtained using a 5 mm Varian 1H–15N Cryo‐Q NMR probe are compared with those from a 3 mm gradient inverse triple resonance probe using a 2 mg sample of the oxazolidinone antibiotic eperezolid in a 3 mm NMR tube. Using the cryogenic NMR probe, a 1H–15N CIGAR‐HMBC spectrum in which most previously reported long‐range couplings are observed was recorded in ∼10 min; almost all of the expected long‐range responses were observed within 26 min. Acquiring the same data set with identical parameters using a conventional 3 mm gradient inverse triple resonance probe gave data that were of substantially lower quality. Acquiring data comparable to the 26 min cryogenic probe data with the conventional 3 mm probe required ∼4 h to observe all of the responses and ∼18 h to obtain a spectrum with a signal‐to‐noise ratio comparable to the data set acquired with the cryogenic NMR probe. Copyright © 2001 John Wiley & Sons, Ltd.
Contact vs solvent‐separated ion pairs: a 7Li and 13C solid‐state NMR study of organolithium compounds
Authors: Kühnen Martin , Günther Harald , Amoureux Jean‐Paul , Fernandéz Christian 
Published: August 2002

Abstract7Li and 13C solid‐state magic angle spinning NMR spectra were measured for three benzyllithium systems, α‐(phenylthio)benzyllithium, α‐phenyl‐α‐lithiodithiane and α‐(trimethylsilyl)benzyllithium, stabilized by different ligands (THF, PMDTA, TMEDA, [12]crown‐4). They were analyzed with respect to the 7Li quadrupole parameters χ(7Li) and η(7Li) and the chemical shifts δ(6,7Li) and δ(13C), respectively. On the basis of X‐ray and solution NMR data from the literature, it is shown that solvent‐separated ion pairs (SIP) can be distinguished from contact ion pairs (CIP) by the different magnitudes of χ(7Li) and typical shifts for δ(6,7Li) and δ(13C). Systems with 2 mol equiv. crown ether ligand [12]crown‐4 exist exclusively as SIP structures and show χ(7Li) values < 50 kHz, whereas for CIP structures we find χ(7Li) > 80 kHz. Copyright © 2001 John Wiley & Sons, Ltd.
Stage‐dependent and alternative splicing of sGnRH messengers in rainbow trout testis during spermatogenesis
Authors: Uzbekova Svetlana , Ferriúre François , Guiguen Yann , Bailhache Thierry , Breton Bernard , Lareyre Jean‐Jacques 
Published: August 2002

AbstractThe gonadotropin releasing hormone (GnRH) has long been considered as a neuropeptide involved in the control of the reproductive cycle. However, the presence of GnRH and its receptors in various tissues, including ovary and testis, suggests a role as autocrine/paracrine factor. In the present study, we report the expression of the sGnRH‐1 and sGnRH‐2 genes encoding salmon GnRH in rainbow trout testis throughout testicular development and spermatogenesis. We demonstrate that both sGnRH mRNA are expressed prior of sexual differentiation. In adult, northern blot analysis indicates that sGnRH‐2 transcripts are expressed in the testis at higher levels than sGnRH‐1 messengers. Moreover, we observed that the expression of sGnRH‐2, and not sGnRH‐1, messengers was stage‐dependent. sGnRH‐2 mRNA expression decreases at the onset and progressively rebounds at the end of spermatogenesis. In addition, we demonstrate that a complex stage‐dependent and differential splicing of the sGnRH‐2 messengers occurs throughout spermatogenesis. We isolated five transcripts corresponding to sGnRH‐2 messengers. Two of them may encode a novel and shortened GnRH‐associated peptide containing 18 residues instead of 46. Our data provide new insight in the putative role of GnRH and GAP peptides as autocrine/paracrine factors of spermatogenesis. Mol. Reprod. Dev. 59:1–10, 2001. © 2001 Wiley‐Liss, Inc.
Embryonic hatching enzyme strypsin/ISP1 is expressed with ISP2 in endometrial glands during implantation
Authors: O'Sullivan Colleen M. , Liu Shi Ying , Karpinka J. Bradley , Rancourt Derrick E. 
Published: August 2002

AbstractEmbryo hatching and outgrowth are the first critical steps on the way to a successful pregnancy. It is generally held that serine proteases are responsible for this process, although the exact mechanisms of action are not clearly understood. Recently, we described two novel implantation serine proteinase (ISP) genes that are expressed during the implantation period. The ISP1 gene encodes the embryo‐derived enzyme strypsin, which is necessary for blastocyst hatching in vitro and the initiation of invasion. The ISP2 gene, which encodes a related tryptase, is expressed in endometrial glands and is regulated by progesterone during the peri‐implantation period. Based on similarities between ISP2 gene expression and that of a progesterone‐regulated lumenal serine proteinase activity associated with lysis of the zona pellucida, we have suggested that the strypsin related protein, ISP2, may encode a zona lysin proteinase. As tryptases naturally assemble to form tetrameric structures, we have hypothesized that ISP1 and ISP2 tetramerize to form strypsin and lysin, respectively. In this study, we demonstrate that like ISP2, the ISP1 gene is also expressed in endometrial glands and is positively regulated by progesterone during implantation. Using in situ hybridization of adjacent tissue sections, we show that the ISP1 and ISP2 genes are co‐expressed within the endometrial gland. Following evidence that ISP1 and 2 can efficiently form homotetramers and heterotetramers in silico, we suggest that ISP heterotetramers may be also be secreted into the uterine lumen during the implantation period. That the embryonic hatching enzyme, may also be secreted into the uterine lumen from uterus, may provide insight into the mechanisms of hatching and implantation initiation. Mol. Reprod. Dev. 62: 328–334, 2002. © 2002 Wiley‐Liss, Inc.
Expression of myostatin pro domain results in muscular transgenic mice
Authors: Yang Jinzeng , Ratovitski Tamara , Brady James P. , Solomon Morse B. , Wells Kevin D. , Wall Robert J. 
Published: August 2002

AbstractMyostatin, a member of the TGF‐β family, negatively regulates skeletal muscle development. Depression of myostatin activity leads to increased muscle growth and carcass lean yield. In an attempt to down‐regulate myostatin, transgenic mice were produced with a ribozyme‐based construct or a myostatin pro domain construct. Though the expression of the ribozyme was detected, muscle development was not altered by the ribozyme transgene. However, a dramatic muscling phenotype was observed in transgenic mice carrying the myostatin pro domain gene. Expression of the pro domain transgene at 5% of β‐actin mRNA levels resulted in a 17–30% increase in body weight (P < 0.001). The carcass weight of the transgenic mice showed a 22–44% increase compared with nontransgenic littermates at 9 weeks of age (16.05 ± 0.67 vs. 11.16 ± 0.28 g in males; 9.99 ± 0.38 vs. 8.19 ± 0.19 g in females, P < 0.001). Extreme muscling was present throughout the whole carcass of transgenic mice as hind and fore limbs and trunk weights, all increased significantly (P < 0.001). Epididymal fat pad weight, an indicator of body fat, was significantly decreased in pro domain transgenic mice (P < 0.001). Analysis of muscle morphology indicated that cross‐sectional areas of fast‐glycolytic fibers (gastrocnemius) and fast‐oxidative glycolytic fibers (tibialis) were larger in pro domain transgenic mice than in their controls (P < 0.01), whereas fiber number (gastrocnemius) was not different (P > 0.05). Thus, the muscular phenotype is attributable to myofiber hypertrophy rather than hyperplasia. The results of this study suggest that the over‐expression of myostatin pro domain may provide an alternative to myostatin knockouts as a means of increasing muscle mass in other mammals. Mol. Reprod. Dev. 60: 351–361, 2001. © 2001 Wiley‐Liss, Inc.
Real‐time imaging of β‐lactoglobulin‐targeted luciferase activity in the mammary glands of transgenic mice
Authors: Barash Itamar , Reichenstein Moshe 
Published: August 2002

AbstractThis study was aimed at establishing a new platform for real‐time monitoring of milk‐protein gene expression in the mammary glands. A transgenic reporter composed of the β‐lactoglobulin (BLG)/luciferase hybrid gene was targeted to the mammary glands of pregnant and lactating mice and luciferase activity was imaged in vivo with a low‐light imaging system. The mammary glands of a 17‐day pregnant mouse occupied an area comparable to that of a 6‐day lactating mouse. Nevertheless, the intensity of the luciferase signal was much weaker and confined to regions in the inguinal and thoracic glands. A few small and defined locations of higher expression were also detected, indicating diversity in the initiation of this transgenic milk protein expression. In the lactating mice, high inter‐ and intra‐heterogeneity among regions in a particular gland and among glands was demonstrated, and confirmed by ex vivo analysis of luciferase activity in mammary biopsies. The lack of correlation between luciferase activities and levels of β‐casein accumulation in these biopsies resulted, most probably, from the longer half‐life of the native milk protein, compared to the activity of the transgenic marker in the tissue. Unilateral sealing of mammary glands for 4 hr resulted in complete abrogation of luciferase activity, establishing the BLG/luciferase transgene as a reliable tool to follow short‐term stimuli. Dispersed mammary epithelial cells preserved luciferase activity in culture, and thus could be used for following mammary gland development after re‐implantation. The bioluminescence‐based methodology presented here eliminates averaging of heterogeneity in gene expression among glands, and misinterpretations resulting from sampling biopsies taken from inactive regions. Imaging luciferase expression in the mammary glands may enable an accurate monitoring of milk‐protein gene expression during cyclic periods of development and apoptosis in a limited number of animals, and could be applied for reporting the consequences of selected drugs on milk‐protein gene expression. Mol. Reprod. Dev. 61: 42–48, 2002. © 2002 Wiley‐Liss, Inc.
Carbohydrate‐based interactions of oviductal sperm reservoir formation—studies in the pig
Authors: Wagner Andrea , Ekhlasi‐Hundrieser Mahnaz , Hettel Christiane , Petrunkina Anna , Waberski Dagmar , Nimtz Manfred , Töpfer‐Petersen Edda 
Published: August 2002

AbstractCompetitive inhibition of sperm to explants of the oviductal epithelium was used to study the complementary receptor system that may be involved in the establishment of the oviductal sperm reservoir in the pig. Sperm binding to the oviductal explants is expressed as Binding Index (BI = sperm cells/0.01 mm2). From a set of glycoproteins with known oligosaccharide structures, only asialofetuin and ovalbumin showed inhibitory activity, indicating that ovalbumin may block high affinity binding sites (IC50 ≅ 1.3 μM) and asialofetuin low affinity sites (IC50 ≅ 18 μM) of the complementary receptor systems, whereas fetuin carrying terminal sialic acid has no effect. Ovalbumin glycopeptides were isolated by Con A affinity chromatography and reverse‐phase HPLC following tryptic digestion. Glycopeptides and enzymatically released glycans were analyzed by MS, and were shown to represent preferentially the two high mannose type glycans (Man)5(GlcNAc)2and (Man)6(GlcNAc)2, and as a minor component the hybrid type glycan (Hex)4(GlcNAc)5. Glycopeptides (84% inhibition) and glycans (81% inhibition) significantly reduced sperm‐oviduct binding at a concentration of 3 μM, whereas the deglycosylated peptides showed no inhibitory activity. Mannopentaose (IC50 ≅ 0.8 μM) representing the oligomannose residue of the high mannose glycans of ovalbumin was as effective as ovalbumin. These data indicate that the carboyhdrate‐based mechanisms underlying the formation of the oviductal sperm reservoir in the pig is the result of the concerted action of at least the high‐affinity binding sites for oligomannose or nonreducing terminal mannose residues and low‐affinity binding of galactose. Mol. Reprod. Dev. 61: 249–257, 2002. © 2002 Wiley‐Liss, Inc.
Improved subtraction by adiabatic FAIR perfusion imaging
Authors: Schepers Janneke , Garwood Michael , van der Sanden Boudewijn , Nicolay Klaas 
Published: August 2002

AbstractFor pulsed arterial spin labeling techniques (e.g., FAIR), mismatches between the imaging and inversion slice profile result in a nonperfusion‐related offset. Several methods have been proposed to reduce subtraction errors in FAIR imaging. Here an acquisition method for FAIR experiments based on adiabatic principles is proposed. It is shown that with adiabatic pulses the same pulse can be used for labeling and echo refocusing, thereby reducing the mismatch between imaging and labeling slice. A twofold reduction in subtraction errors compared to 5‐lobe sinc excitation was shown both experimentally and by simulation. Magn Reson Med 47:330–336, 2002. © 2002 Wiley‐Liss, Inc.
Comparison of diffusion‐weighted high‐resolution CBF and spin‐echo BOLD fMRI at 9.4 T
Authors: Lee Sang‐Pil , Silva Afonso C. , Kim Seong‐Gi 
Published: August 2002

AbstractThe quantification of blood oxygenation‐level dependent (BOLD) functional MRI (fMRI) signals is closely related to cerebral blood flow (CBF) change; therefore, understanding the exact relationship between BOLD and CBF changes on a pixel‐by‐pixel basis is fundamental. In this study, quantitative CBF changes induced by neural activity were used to quantify BOLD signal changes during somatosensory stimulation in α‐chloralose‐anesthetized rats. To examine the influence of fast‐moving vascular spins in quantifying CBF, bipolar gradients were employed. Our data show no significant difference in relative CBF changes obtained with and without bipolar gradients. To compare BOLD and CBF signal changes induced by neural stimulation, a spin‐echo (SE) sequence with long SE time of 40 ms at 9.4 T was used in conjunction with an arterial spin labeling technique. SE BOLD changes were quantitatively correlated to CBF changes on a pixel‐by‐pixel and animal‐by‐animal basis. Thus, SE BOLD‐based fMRI at high magnetic fields allows a quantitative comparison of functional brain activities across brain regions and subjects. Magn Reson Med 47:736–741, 2002. © 2002 Wiley‐Liss, Inc.
Visualization of neural tissue water compartments using biexponential diffusion tensor MRI
Authors: Inglis B.A. , Bossart E.L. , Buckley D.L. , Wirth E.D. , Mareci T.H. 
Published: August 2002

AbstractThe apparent diffusion tensor (ADT) imaging method was extended to account for multiple diffusion components. A biexponential ADT imaging experiment was used to obtain separate images of rapidly and slowly diffusing water fractions in excised rat spinal cord. The fast and slow component tensors were compared and found to exhibit similar gross features, such as fractional anisotropy, in both white and gray matter. However, there were also some important differences, which are consistent with the different structures occupying intracellular and extracellular spaces. Evidence supporting the assignment of the two tensor components to extracellular and intracellular water fractions is provided by an NMR spectroscopic investigation of homogeneous samples of brain tissue. Magn Reson Med 45:580–587, 2001. © 2001 Wiley‐Liss, Inc.
Single‐voxel oversampled J‐resolved spectroscopy of in vivo human prostate tissue
Authors: Swanson Mark G. , Vigneron Daniel B. , Tran Tuan‐Khanh C. , Sailasuta Napapon , Hurd Ralph E. , Kurhanewicz John 
Published: August 2002

AbstractSingle‐voxel J‐resolved spectroscopy with oversampling in the F1 dimension was used to obtain water unsuppressed 1H spectra of in situ human prostate tissue in 40 previously untreated prostate cancer patients. Based on T2‐weighted MRI and previous biopsy information, voxels were placed in regions of benign or malignant peripheral zone tissue, or in regions of predominantly glandular or stromal benign prostatic hyperplasia (BPH) within the central gland. The addition of a second J‐resolved dimension allowed for the observation of the J‐modulation of citrate, as well as the resolution of polyamines from overlapping choline and creatine signals. Regions of healthy peripheral zone tissue and glandular BPH all demonstrated high levels of citrate and polyamines, with consistent coupling and J‐modulation patterns. Conversely, regions of malignant peripheral zone tissue and stromal BPH demonstrated low levels of citrate and polyamines consistent with prior in vivo and ex vivo studies. Moreover, water T2 relaxation times determined for healthy peripheral zone tissue (mean 128 ± 15.2 msec) were significantly different than for malignant peripheral zone tissue (mean 88.0 ± 14.2 msec, P = 0.005), as well as for predominantly glandular (mean 92.4 ± 12.2 msec, P = 0.009) and stromal BPH (mean 70.9 ± 12.1 msec, P = 0.003). This preliminary study demonstrates that J‐resolved spectroscopy of the in situ prostate can be acquired, and the information obtained from the second spectral dimension can provide additional physiologic information from human prostate tissue in a reasonable amount of time (< 10 min). Magn Reson Med 45:973–980, 2001. © 2001 Wiley‐Liss, Inc.
On T2‐shortening by weakly magnetized particles: The chemical exchange model†
Authors: Brooks Rodney A. , Moiny Francis , Gillis Pierre 
Published: August 2002

AbstractChemical exchange (CE) theory is compared with two theories of T2‐shortening caused by microscopic magnetic centers: inner‐ and outer‐sphere relaxation theory (long‐echo limit) and mean gradient diffusion theory (short‐echo limit). The CE equation is shown to be identical to these theories in the respective limits and appropriate parameter relationships are derived for spherical particles. The theories are then compared with computer simulations of spherical particles and with a recent general theory, with good agreement in the asymptotic regions. The CE model also reproduces the essential relaxation characteristics in the intermediate range. Finally, good agreement of a CE model with simulations for magnetized cylinders is also demonstrated. The discussion is limited to weakly magnetized particles such that the maximum phase shift during an echo interval is less than one radian, permitting the use of the Luz‐Meiboom CE equation. Magn Reson Med 45:1014–1020, 2001. Published 2001 Wiley‐Liss, Inc.
Improved diffusion‐weighted single‐shot echo‐planar imaging (EPI) in stroke using sensitivity encoding (SENSE)
Authors: Bammer Roland , Keeling Stephen L. , Augustin Michael , Pruessmann Klaas P. , Wolf Roswitha , Stollberger Rudolf , Hartung Hans‐Peter , Fazekas Franz 
Published: August 2002

AbstractDiffusion‐weighted single‐shot EPI (sshEPI) is one of the most important tools for the diagnostic assessment of stroke patients, but it suffers from well known artifacts. Therefore, sshEPI was combined with SENSitivity Encoding (SENSE) to further increase EPI's potential for stroke imaging. Eight healthy volunteers and a consecutive series of patients (N = 8) with suspected stroke were examined with diffusion‐weighted SENSE‐sshEPI using different reduction factors (1.0 ≤ R ≤ 3.0). Additionally, a high‐resolution diffusion‐weighted SENSE‐sshEPI scan was included. All examinations were diagnostic and of better quality than conventional sshEPI. No ghostings or aliasing artifacts were discernible, and EPI‐related image distortions were markedly diminished. Chemical shift artifacts and eddy current‐induced image warping were still present, although to a markedly smaller extent. Measured direction‐dependent diffusion‐coefficients and isotropic diffusion values were comparable to previous findings but showed less fluctuation. We have demonstrated the technical feasibility and clinical applicability of diffusion‐weighted SENSE‐sshEPI in patients with subacute stroke. Because of the faster k‐space traversal, this novel technique is able to reduce typical EPI artifacts and increase spatial resolution while simultaneously remaining insensitive to bulk motion. Magn Reson Med 46:548–554, 2001. © 2001 Wiley‐Liss, Inc.
T and T maps derived in vivo from the rat using longitudinally detected electron spin resonance phase imaging: Application to abdominal oxygen mapping
Authors: Panagiotelis Ioannis , Nicholson Ian , Foster Margaret A. , Hutchison James M.S. 
Published: August 2002

AbstractA novel imaging modality is introduced which uses radiofrequency longitudinally detected electron spin resonance (RF‐LODESR). It is capable of providing qualitative and semiquantitative information on a variety of parameters reflecting physiological function, the most significant being tissue oxygenation. Effective spin‐lattice (T) and spin‐spin (T) electronic relaxation time maps of the abdomen of living 200‐g rats were generated after intravenous administration of a triarylmethyl free radical (TAM). These maps were used to evaluate oxygen distribution. Differences between the liver, kidneys, and bladder were noted. Conclusions were made regarding the distribution, perfusion, and excretion rate of the contrast medium. Ligature‐induced anoxia in the kidney was also visualized. LODESR involves transverse ESR irradiation with a modulated excitation, and observing oscillations in the spin magnetization parallel to the main magnetic field. The T and T maps were calculated from a set of LODESR signal phase images collected at different detection frequencies. Each phase image also provides qualitative information on tissue oxygen levels without any further processing. This method presents an alternative to the conventional transverse ESR linewidth‐based oximetry methods, particularly for animal whole‐body imaging applications. Magn Reson Med 46:1223–1232, 2001. © 2001 Wiley‐Liss, Inc.
Continuous myonuclear addition to single extraocular myofibers in uninjured adult rabbits
Authors: McLoon Linda K. , Wirtschafter Jonathan D. 
Published: August 2002

AbstractExtraocular muscles (EOM) are unique among mammalian skeletal muscles in that they normally express molecules associated with muscle development and regeneration. In this study we show that satellite cells of EOM, unlike those of other skeletal muscles, continually divide in the normal, uninjured adult. Adult EOM contained activated satellite cells positive for the myogenic regulatory factor MyoD. EOM satellite cells did not require a prolonged activation period prior to onset of cell division and differentiation in vitro. EOM satellite cells incorporated bromodeoxyuridine (brdU), a marker for cell division, and with longer postlabeling survival, brdU‐labeled nuclei populated EOM myofibers. This was not seen with leg muscle. These findings suggest the possibility that continual division of satellite cells and fusion of their daughter myocytes with existing adult EOM myofibers contribute to the unique sparing or susceptibility of EOM to certain muscle diseases. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002