bluuebunny/crossref_metadata_2025 huggingface dataset:
Further simplification of ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti‐htlv‐i igg using microplates and fluororeader
Authors: Ishikawa Setsuko , Hashida Seiichi , Nakamoto Hidetaka , Tanaka Satoshi , Kojima Masaaki , Ishikawa Eiji
Published: March 2007

In a previously reported ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti‐HTLV‐I IgG, polystyrene beads were handled with tweezers, and bound b̃‐D‐galactosidase activity was measured with a fluorometer. The use of tweezers was causative of false‐positivity by carryover, and testing many samples was difficult. Recently, these drawbacks have been minimized using microplates and a fluororeader. However, tweezers were still required in the initial and final steps. In the present study, the immune complex, comprising 2,4‐dinitrophenyl‐antigen, anti‐HTLV‐I IgG, and antigen‐b̃‐D‐galactosidase conjugate, was formed in and trapped onto microplate wells coated with (anti‐2,4‐dinitrophenyl group) IgG. Subsequently, the microplate wells were incubated with ϵN‐2,4‐dinitrophenyl‐L‐lysine and polystyrene beads, modified by attaching to plates through cylindrical bars and coated with (antihuman IgG γgM‐chain) IgG, to transfer the immune complex from the microplate wells to the modified polystyrene beads. Alternatively, modified polystyrene beads coated with (anti‐2,4‐dinitrophenyl group) IgG and microplate wells coated with (antihuman IgG γgM‐chain) IgG were substituted for microplate wells coated with (anti‐2,4‐dinitrophenyl group) IgG and modified polystyrene beads coated with (antihuman IgG γgM‐chain) IgG, respectively. The fluorescence intensity for bound b̃‐D‐galactosidase activity was quickly measured with a fluororeader. Thus the modified polystyrene beads were transferred from wells to wells more quickly and easily without tweezers, eliminating false‐positivity due to carryover, and it became easy to test many samples with high sensitivity and reliability, although the assay of bound b̃‐D‐galactosidase activity became slightly more time‐consuming.©1995 wiley‐Liss, inc.
Use of pyruvate oxidase to overcome pyruvate inhibition during the lactate to pyruvate reaction for assaying lactate dehydrogenase in serum
Authors: Murthy Vadiraja V.
Published: March 2007

Automated assays of lactate dehydrogenase (LD) in serum are based on measuring the rate of NADH produced in a reverse LD reaction using lactate and NAD. The observed nonlinearity of LD reaction used in earlier assays performed in phosphate buffers has generally been attributed to the formation of a ternary complex of NAD, pyruvate, and phosphate. This is not satisfactory to explain the course of assay reaction carried out in organic buffers.

Investigation of the possible causes of nonlinearity during the course of the reverse LD reaction during LD assays performed in Tris or other organic buffers indicated that inhibition of LD activity by pyruvate may be chiefly responsible for the observed effects, especially in serum exhibiting abnormally high LD enzyme activity. Most of the LD activity in serum was inhibited by 5 mMoles/L pyruvate. By contrast, the LD isoenzyme activities were inhibited partially at 0.5 mMole/L pyruvate, LD1 being the most and LD4 the least susceptible.

In assays of serum samples with abnormally high LD and PYR concentration using LD reagent containing Tris buffer, pH 9.3, the inclusion of a bacterial pyruvate oxidase (PO) enabled the removal of pyruvate accumulating in situ, making it possible to assay LD activity in the absence of inhibitory concentration of pyruvate. The inclusion of 10 U/L of PO in our routine LD reagent was sufficient to overcome pyruvate inhibition, thus permitting the assay of serum exhibiting high LD activity, hence the extension of the upper limits of linearity of LD assay without compromising assay performance.
Urinary gonadotropin peptide: Collection of specimens and cutoff levels
Authors: Plebani Mario , Navaglia Filippo , Bacelle Lucio , Polonio Simonetta , Lazzari Francesca , Marchetti Maria
Published: March 2007

A low‐molecular‐weight form of human chorionic gonadotropin (hCG), urinary gonadotropin peptide (UGP), has been isolated from the urine of pregnant women and of patients with cancer, mainly of gynecological origin. The clinical value of UGP measurement in gynecological diseases is under investigation but a preliminary study is necessary in order to ascertain whether there is a circadian rhythm in UGP production, to clarify the best way to express the results, and to establish the cutoff and decisional values.

In our work we demonstrated a significant correlation between the UGP output and the UGP excretion normalized for urinary creatinine. A very significant agreement was even found in 24‐hr urine collections and UGP concentration of a single morning specimen from the same patients. No evident circadian rhythm was found, although some patients presented morning levels of UGP higher than in other collections.

UGP postmenopausal levels were higher than premenopausal. The cutoff level, adopting the 95.0 percentile, was 200 pmol/mol creatinine.
Psa immunoreactivity detected in lncap cell medium, breast tumor cytosol, and female serum
Authors: Wu James T. , Zhang Ping , Astill Mark E. , Wilson Lori W. , Lyons Bradley W. , Wu Lily L. , Stephenson Robert
Published: March 2007

We made an effort to identify a reliable source for obtaining large quantities of both free (PSA) and PSA–ACT complex for the preparation of the calibrator for the PSA assay. Using size exclusion chromatography, we found both free PSA and PSA–ACT complex in the conditioned cell medium of the LNCaP cell line, which was derived from a human metastatic adenocarcinoma of the prostate. An assay specific for PSA–ACT reacted only with the PSA–ACT complex from cells grown in serum‐free medium, and not with the complex from the cell medium grown in 10% calf serum. We also found both free PSA and PSA–ACT complex in 15% of cytosols prepared from breast tumor tissues; the cytosol PSA concentrations ranged from 0.1 to 110 ng/ml. No correlation was found between cytosol PSA and concentrations of estrogen receptor, progestin receptor, epidermal growth factor receptor, cathepsin D, or the ectodomain of c‐erbB‐2 protein. Based on chromatographic characterizations and the slope of their dose‐response curves, it appears that both free PSA and PSA–ACT complex found in the cytosols are similar to PSA complex from the cell medium and the serum of prostate cancer patients. Ectopic PSA was also detected in pooled sera from patients with breast, ovarian, pancreatic, and colon carcinoma. The PSA concentrations in these serum pools increased with the level of their dominant tumor marker. In any event, the LNCaP cell medium appears to be a reliable source for obtaining both free and ACT‐complexed PSA of human tumor origin for the preparation of PSA assay calibrators.
Development of a microplate elisa for free psa and psa–act complex in serum
Authors: Wu James T. , Wilson Lorraine W.
Published: March 2007

An ELISA on microplate was established for the total serum PSA. We selected the monoclonal antibody for the assay from commercial sources making certain that it reacted with both free PSA and PSA–α1‐antichymotrypsin (PSA–ACT) complex from human serum with similar affinity (so‐called “equimolar”). We also chose a test format with polyclonal anti‐PSA antibodies coated on the well and monoclonal anti‐PSA antibodies for quantification to gain higher test sensitivity. Two different sample volumes from each specimen, 5 and 50 m̈l, were used for the assay in order not only to further increase test sensitivity and improve precision at both low and highly elevated PSA concentrations, but also to widen the assay concentration range (0–500 ng total PSA per ml). Using two sample volumes also reduces any hook effect and shortens the turn‐around time because repeated determinations are usually required when specimens contain highly elevated PSA concentrations. The use of pooled sera containing approximately 95% PSA–ACT complex and 5% free PSA as a calibrator allows for a close matching of the calibrator with serum specimens in immunoreactivity and PSA composition. Moreover, our assay shows no hook effect up to 15,000 ng/ml. The within‐day precision (% CV) in the critical concentration range of 4–12 ng/mL is approximately 5%. The PSA values obtained from this assay correlate well with that of the Hybritech kit (γ = 0.998, slope equals to 1.033), indicating that this kit can replace the Hybritech Tandem E PSA kit for serum PSA determination in clinical laboratories.
Evaluation of a dipstick method for the detection of human immunodeficiency virus infection
Authors: Beristain Claudio N. , Federico Rojkin L. , Lorenzo Luis E.
Published: March 2007

Serology has been a fundamental tool to prevent post‐transfusional infection with human immunodeficiency virus (HIV) and for epidemiological surveys, the first step to attempt control of the pandemia. Enzyme immunoassay is in widespread use. Nevertheless, simpler methods are needed in many countries, where laboratory facilities and trained personnel are limited, and HIV prevalence is high. The evaluation of a simple and noninstrumented HIV antibody test is presented here. The test employs synthetic antigens of HIV‐1 and HIV‐2 attached to the teeth of a polystyrene comb, which fit into the wells of standard microtiter plates where samples are diluted. Captured antibodies are developed with colloidal gold‐labeled Protein A. Three seroconversion panels plus 662 samples were tested, including HIV‐1 and HIV‐2‐infected individuals, normal blood donors, and a noninfected baby born to a seroreactive mother. When compared with enzyme‐linked immunosorbent assay (ELISA) and Western blot, the dipstick showed 100% sensitivity and 98.7% specificity. The simplicity of result evaluations and excellent reagent stability make the dipstick suitable for small blood banks and for epidemiological surveys.
Further characterization of the plasma lipoprotein(a) distribution
Authors: Craig Wendy , Poulin Sue , Bostom Andrew , Eaton Charles , Laurino Joseph , Ledue Thomas , Ritchie Robert
Published: March 2007

The plasma lipoprotein(a) [Lp(a)] distribution in caucasians is heavily skewed to the right, with evidence of bimodality. As there is a well‐described inverse relationship between apolipoprotein(a) [apo(a)] size and Lp(a) concentration, it is likely that the presence of multiple apo(a) isoforms of differing frequency has a significant impact on the final distribution of Lp(a) concentrations. We have previously described an immunoblot method for examining the relationship between apolipoprotein(a) [apo(a)] size and lipoprotein(a) [Lp(a)] mass among samples heterozygous for apo(a) size, thus eliminating confounding by null or undetected apo(a) isoforms. In the present study, this method has been applied to examine the plasma Lp(a) distribution, independent of the effects of apo(a) isoform size and frequency. Seventy subjects heterozygous for apo(a) size were studied. To take into account the inverse relationship (P <0.001) between apo(a) isoform size and Lp(a) concentration, Lp(a) data associated with each apo(a) isoform were normalized as multiples of the median Lp(a) concentration for that isoform. These apo(a) isoform‐independent Lp(a) data demonstrated a strikingly multimodal distribution, with five major peaks. The relative frequencies of Lp(a) peaks 1–5 were 17.1%, 15.0%, 35.7%, 23.6%, and 8.6%, and associated median Lp(a) concentrations were 1.0, 6.2,15.0, 21.8, and 39.6 mg/dL, respectively. Multivariate analysis demonstrated that apo(a) isoform size accounted for 23% and isoform‐independent Lp(a) peaks for 59.5% of the variation in Lp(a) concentration. Further investigation of the characteristics of the apo(a) isoform‐independent Lp(a) distribution is warranted.
Estimating oxygen saturation of blood in vivo with MR imaging at 1.5 T
Authors: Wright Graham A. , Hu Bob S. , Macovski Albert
Published: March 2007

The use of magnetic resonance (MR) imaging is investigated for noninvasively estimating the oxygen saturation of human blood (%HbO2) in vivo by means of relaxation characteristics identified in earlier MR spectrometry studies. To this end, a sequence is presented for determining the T2 of vascular blood in regions in which motions of the body and of the blood itself present a major challenge. With use of this sequence on a commercial 1.5‐T whole‐body imager, the relationship between the T2 and %HbO2 of blood is calibrated in vitro for the conditions expected in vivo. T2 varies predictably from about 30 to 250 msec as %HbO2 varies from 30% to 96%. T2 values measured in situ for vascular blood in the mediastinum of several healthy subjects qualitatively reflected the behavior observed in vitro. Estimates of %HbO2 for these vessels obtained with the in vitro calibration appear reasonable, particularly for venous blood, although difficulties arise in selecting the appropriate calibration factors. These encouraging initial results support a more systematic study of potential sources of error and an examination of the accuracy of in vivo measurements by comparison with direct measurements of %HbO2 in vessels.
Intraluminal contrast enhancement and MR visualization of the bowel wall: Efficacy of PFOB
Authors: Rubin Daniel L. , Muller Holde H. , Nino‐Murcia Matilde , Sidhu Manrita , Christy Valerie , Young Stuart W.
Published: March 2007

Efforts to develop satisfactory intraluminal gastrointestinal contrast agents for magnetic resonance (MR) imaging have focused on depicting only the bowel lumen to exclude possible involvement by a pathologic process. To determine whether the bowel wall can be adequately imaged with use of the contrast agent and whether bowel wall visualization is a better index of the utility of the contrast agent for MR imaging, perfluorooctylbromide (PFOB) was studied in human subjects. Twenty consecutive patients referred for abdominal or pelvic MR imaging were selected. All patients were given 400–1,000 mL of PFOB orally. MR imaging was performed at 0.38 and 1.5 T with T1‐ and T2‐weighted spin‐echo pulse sequences before and after administration of PFOB. The images were graded independently by three blinded readers. All readers reported significantly superior conspicuity of the bowel lumen and wall after PFOB than before PFOB administration (P < .002). Among the post‐PFOB studies, those with superior bowel wall visualization demonstrated superior overall image quality. In three patients, lesions were optimally demonstrated because the relationship of the process to the bowel wall, rather than just to the lumen, was identified. In two patients, masses arising within the bowel wall could be identified prospectively only when the bowel wall was adequately imaged. The authors conclude that while lumen identification is improved with PFOB, its greatest clinical utility may be in facilitating intestinal wall visualization.
Evaluation of a simple method for reconstructing asymmetrically sampled echo data
Authors: Mugler John P. , Brookeman James R.
Published: March 2007

A simple method for reconstructing echo data with a large degree of sampling asymmetry was investigated. The method is based on the application of an optimized data sampling window before standard Fourier transform magnitude reconstruction. The performance of this “windowed direct” reconstruction was evaluated with theoretical simulations and experimental measurements and compared with that of the half‐Fourier method. With the proper selection of data sampling window parameters, highly asymmetric echo data reconstructed with standard Fourier transform magnitude algorithms produced images similar in quality to those reconstructed with the half‐Fourier method. Windowed direct reconstruction provides a simple and computationally fast alternative to more sophisticated algorithms and may be particularly applicable for specialized or developmental applications.
Rectal barium in pelvic MR imaging: Initial results
Authors: Panaccione John L. , Ros Pablo R. , Torres Gladys M. , Burton Sharon S.
Published: March 2007

Pelvic magnetic resonance (MR) imaging is limited by lack of an effective bowel contrast agent. This study was performed to evaluate the efficacy of rectally administered barium sulfate as a contrast agent in pelvic MR imaging. Thirty‐two patients were studied retrospectively to evaluate anatomic definition of the rectosigmoid colon. A commercially available barium sulfate suspension was administered rectally in 19 patients. Thirteen patients were imaged without barium. In the latter patients, anatomic definition of the rectum and sigmoid colon was poor to fair with all pulse sequences. Delineation of the rectum and sigmoid colon improved in patients who received rectal barium, owing to distention and marking of the bowel by the predominately low‐signal‐intensity barium. Barium is a safe, inexpensive negative contrast agent for bowel that may improve pelvic MR imaging.
OMR, a positive bowel contrast agent for abdominal and pelvic MR imaging: Safety and imaging characteristics
Authors: Patten Randall M. , Moss Albert A. , Fenton Theresa A. , Elliott Sharon
Published: March 2007

To determine the safety and imaging characteristics of OMR — an effervescent solution of ferric ammonium citrate — as a bowel contrast agent, magnetic resonance (MR) imaging at 1.5 T was performed in 29 volunteers. T1‐ and T2‐weighted images of the upper abdomen and pelvis were obtained before and after oral administration of OMR at doses of 100–400 mg of iron in 300–600 mL of water. Respiratory‐ordered phase encoding and presaturation pulses were used routinely for artifact suppression. All dose levels of OMR provided marking of the bowel by increasing intraluminal signal intensity; however, the degree and percentage of small bowel opacification appeared more prominent at higher dose levels of iron. Semisolid or watery bowel movements were noted in 31% of subjects, but no clinically important laboratory abnormalities were seen. OMR improved delineation of the head of the pancreas on T1‐weighted images in 72% of subjects but was less useful in defining the body and tail. OMR is a safe and effective bowel contrast agent for MR imaging. Because artifacts due to movement of hyperintense bowel may degrade the images, OMR may be most useful on short TR/TE or fast imaging pulse sequences or when combined with antiperistaltic agents.
MR imaging characteristics of noncancerous lesions of the prostate
Authors: Lovett Karen , Rifkin Matthew D. , McCue Peter A. , Choi Hong
Published: March 2007

Radical prostatectomy specimens from 53 men with clinical stage A or B prostate cancer were retrospectively reviewed and compared with correlative axial T2‐weighted magnetic resonance (MR) images obtained just before surgery. Non‐cancerous lesions were evaluated for signal intensity and location. Focal high‐signal‐intensity areas (n = 72) were present in 81% of patients. The 26% of lesions seen in the central gland all correlated with cystic atrophy. Of the 53 lesions seen in the peripheral prostate, 47 (89%) were cystic atrophy without associated cancer, four (7.5%) cystic atrophy with cancer, and two (3.8%) focal inflammation. Focal low‐signal‐intensity areas (n = 42) were present in 60% of patients. Of the 31% of lesions in the central prostate, one‐fifth correlated with benign prostatic hyperplasia (BPH) and four‐fifths with fibrous tissue. Of the 69% of peripheral lesions, 83% corresponded to fibrous tissue, 10% to BPH, and 7% to normal tissue. Mixed lesions (n = 42) were present in 64% of patients; 86% of these were located centrally and 14% peripherally. All mixed central lesions were BPH; the peripheral lesions were areas of combined cystic atrophy and fibrosis. BPH of low or mixed signal intensity can extend into the peripheral prostate and mimic cancer. High‐intensity cystic atrophy associated with cancer can mimic normal tissue.
Fast, interactive algorithm for segmentation of a series of related images: Application to volumetric analysis of MR images of the heart
Authors: Wang Jin Zhao , Turner David A. , Chutuape Mariano D.
Published: March 2007

Magnetic resonance (MR) cine images of the beating heart have excellent spatial and temporal resolution. Extracting the boundaries of the heart from MR images for volumetric measurements is of considerable interest; however, since the number of images involved is large, tracing the boundaries by hand is tedious and prohibitively time consuming. The authors have developed an interactive method of boundary detection that uses the correlation between the cardiac boundaries on temporally or spatially adjacent images to increase the speed of the process and reproducibility of the measurement. A simulated cine MR study of a phantom (total of 155 images) and cardiac cine studies of two patients (192 images each) were analyzed by two independent observers. Analysis of the phantom data was completed in 5.6 minutes (2.16 seconds per image) by observer 1 and 6.3 minutes (2.4 seconds per image) by observer 2. The percent measurement errors for 31 phantom volumes (30‐120 mL) were 0.96% and 0.83% for observers 1 and 2, respectively. The observers analyzed the patient studies in 14‐23 minutes (4.4‐7.2 seconds per image), with interobserver variabilities of 5.8% and 3.7% for the two patients, respectively. The authors conclude that their flexible, semiautomatic, interactive algorithm allows rapid and reproducible detection of structural boundaries.
MR imagin—histopathologic correlation of thermal injuries induced with interstitial Nd:YAG laser irradiation in the chronic model
Authors: Anzai Yoshimi , Lufkin Robert B. , Farahani Keyvan , Hirschowitz Sharon , Castro Dan J.
Published: March 2007

Magnetic resonance (MR) imaging–histopathologic correlation of thermal injuries induced with interstitial laser irradiation was performed in a chronic model up to 12 weeks after laser exposure. T2‐weighted MR images showed irreversible coagulative necrosis as a low‐signal‐intensity area. A higher‐intensity surrounding area, corresponding to edema, was also present in acute lesions on T2‐weighted images. Serial studies of the chronic model showed that a substantial portion of the interstitial edema zone progressed to coagulative necrosis up to 7 days after laser irradiation. This necrotic zone decreased in size beyond 2 weeks, presumably through biologic healing. MR imaging and pathologic findings correlated well in the chronic model. MR imaging has the potential to depict acute, irreversible thermal damage even before morphologic change is seen at the standard pathologic examination. Recognizing the dynamics of tissue response to interstitial laser irradiation on MR images is valuable for estimation of true lesion volume.
Effect of Gd‐DTPA‐BMA on magnetization transfer: Application to rapid imaging of cardiac ischemia
Authors: Jones Richard A. , Haraldseth Olav , Schjott Jan , Brurok Heidi , Jynge Per , Oksendal Audun N. , Rinck Peter A.
Published: March 2007

The addition of a paramagnetic contrast agent reduces the magnetization transfer effect between the free and restricted proton pools in both agar phantoms and cardiac muscle tissue. This reduction is due to the reduction in the intrinsic T1 of the free proton pool and increases the signal observed after a given magnetization transfer sequence. Images of ex vivo piglet hearts were obtained with a segmented snapshot FLASH (fast low‐angle shot) sequence with a 128 × 128 matrix, four segments, and two signals averaged, resulting in an imaging time of 7 seconds. Magnetization transfer was induced by applying a DANTE (delays alternating with nutations for tailored excitations) pulse sequence in the intersegment interval. This was an efficient method of inducing magnetization transfer because it excites the restricted proton pool across the full frequency spectrum. Ischemia due to occlusion of the left anterior descending branch of the coronary artery could be visualized after infusion of gadolinium di‐ethylenetriaininepentaacetic acid‐bis(methylamide) (DTPA‐BMA). Although the ischemia could be seen with the basic sequence, the contrast between isch‐emic and non‐ischemic tissue improved when the magnetization transfer sequence was included. The most marked improvements in magnetization transfer were achieved with low doses of Gd‐DTPA‐BMA.
Liquid oral magnetic particles as a gastrointestinal contrast agent for MR imaging: Efficacy in vivo
Authors: Rubin Daniel L , Muller Holde H. , Sidhu Manrita K. , Young Stuart W. , Hunke William A. , Gorman William G.
Published: March 2007

Recent in vitro studies suggested there is an optimal range of concentration and viscosity for a liquid formulation of oral magnetic particles (WIN 39996) for magnetic resonance (MR) imaging of the gastrointestinal (GI) tract. To determine whether this formulation is also effective in vivo and whether differing viscosity and administration regimen affect GI distribution of the contrast agent, a range of concentrations of iron (75, 150,and 200 μg/mL) and viscosities (1, 150, and 600 cp) were imaged in dogs at 1.5 T with conventional spin‐echo and fat‐saturation pulse sequences. The effects of dose regimen (single vs divided dose) and subject position (supine vs right lateral decubitus) were also studied. The 75 and 200 μg/mL concentrations were unacceptable for MR imaging, while 150 μ.g/mL was effective. The GI distribution of the contrast agent was affected jointly by viscosity, subject position, and dose regimen. The 150 μg/mL formulation produced excellent GI contrast enhancement in vivo for both 150‐ and 600‐cp viscosities. The choice of optimal viscosity may depend on the preferred administration regimen.
Contrast‐enhanced MR angiography
Authors: Runge Val M. , Kirsch John E. , Lee Charles
Published: March 2007

Magnetic resonance (MR) angiography, although still in its infancy, is recognized as a valuable diagnostic tool. Investigation of the utility of contrast media as applied to MR angiography is, to no surprise, preliminary. In restricted instances, with present techniques, contrast media‐enhanced MR angiography can provide additional valuable diagnostic information. Inspection of two‐dimensional images (as opposed to three‐dimensional projections) and comparison of MR images before and after administration of contrast agent are particularly important. Improved visualization of intracranial aneurysms, arteriovenous malformations, venous anomalies, and arterial occlusions has been demonstrated on three‐dimensional time‐of‐flight MR angiograms after intravenous administration of a gadolinium chelate, relative to studies performed before administration of the contrast agent.
Aortoiliac disease: Two‐dimensional inflow MR angiography with lipid suppression
Authors: Mulligan Susan A. , Doyle Mark , Matsuda Tetsuya , Koslin D. Bradley , Kenney Philip J. , Barton Robert E. , Pohost Gerald M.
Published: March 2007

A magnetic resonance (MR) imaging strategy, SLIP (spatially separated lipid presaturation), which can be incorporated into existing MR imaging and MR angiographic techniques, has been developed to suppress lipid signal. The authors report the clinical application of this technique, with a triple comparison of two‐dimensional inflow MR angiography, with and without SLIP, and x‐ray angiography in patients with aortoiliac disease. SLIP improved visualization of arterial segments, with 50 of 63 (79%) arterial segments visualized versus 41 of 63 (65%) for non‐SLIP MR angiography. The SLIP strategy aids in the depiction of slow or turbulent flow, because the lipid signal is suppressed while the intravascular signal is left undisturbed. Image quality improves because of the combination of decreased background lipid signal intensity and use of the maximum‐intensity‐projection algorithm. Compared with x‐ray arteriography, non‐SLIP MR angiography had a sensitivity and specificity of 60% and 56%, respectively, for detection of lesions with 50%–100% diameter reduction, while SLIP MR angiography had a sensitivity and specificity, respectively, of 53% and 67%.
Two‐point interference method for suppression of ghost artifacts due to motion
Authors: Xiang Qing‐San , Bronskill Michael J. , Henkelman R. Mark
Published: March 2007

A two‐point interference method is introduced for suppression of ghosting due to motion in magnetic resonance imaging. The method requires only two time‐interleaved data acquisitions, without any monitoring of the motion. A postprocessing technique is used to produce a weighted sum of the two acquired images, in which ghosts are suppressed by interference through an automatic regional tuning procedure. The appropriate complex weighting factors are regionally chosen by minimizing the “gradient energy”, which is defined as the sum of squared pixel values in the partial‐derivative maps. The method was tested in both phantoms and volunteers with a variety of imaging protocols. The level of ghost suppression with the two‐point method was found to be comparable to that of the three‐point method described previously by the authors.
Dynamic MR mammography: A technique for potentially reducing the biopsy rate for benign breast disease
Authors: Turkat Terry J. , Klein Barry D. , Polan Ruth L. , Richman Roselyn H.
Published: March 2007

Thirty‐five women with a total of 39 breast lesions detected at mammography and/or physical examination and who were scheduled for surgical biopsy were studied with dynamic magnetic resonance (MR) mammography. Fat‐suppressed, spoiled GRASS (gradient‐recalled acquisition in the steady state) sequences were performed before and after administration of gadopentetate dimeglumine. T1‐weighted spin‐echo and fat‐suppressed T2‐weighted fast spin‐echo images were also obtained. By measuring percentage signal intensity change in lesions on the spoiled GRASS images after contrast agent injection, the authors achieved a sensitivity of 100% and a specificity of 83.3% in differentiating benign from malignant lesions (24 benign, 15 malignant), with biopsy results as the standard. This dynamic MR mammography technique deserves further evaluation.
Frequency response of prospectively gated phase‐contrast MR velocity measurements
Authors: Frayne Richard , Rutt Brian K.
Published: March 2007

The authors developed and experimentally verified expressions that describe the frequency response of prospectively gated phase‐contrast magnetic resonance velocity measurements. Both interleaved and noninterleaved phase‐contrast techniques were evaluated. The primary determinants of the frequency response were (a) the number of interleaved acquisitions (N), (b) the time between acquisitions (ΔT), and (c) the degree of balance between the first moments of the velocity‐encoding gradients. To quantify the last factor, an imbalance parameter (U) was defined. Depending on the chosen implementation and U, deviations from the ideal frequency responses were predicted and observed. The expressions also revealed an advantage of interleaved acquisitions that use a one‐sided gradient configuration: no changes in the frequency response. The effects of concurrently encoding orthogonal velocity components with a Hadamard four‐point scheme were examined.
Errors in quantitative dynamic three‐dimensional keyhole MR imaging of the breast
Authors: Plewes Donald B. , Bishop Jonathan , Soutar Ian , Cohen Eve
Published: March 2007

Three‐dimensional (3D) keyhole magnetic resonance (MR) imaging has been proposed as a means of providing dynamic monitoring of contrast agent uptake by breast lesions, with complete breast coverage and high spatial and temporal resolution. The 3D keyhole technique dynamically samples the central regions of k‐space in both phase‐encoding directions and provides high‐frequency data from a precon‐trast acquisition. Errors due to data truncation with two‐dimensional and 3D region‐of‐lnterest measurements are estimated from a numerical simulation of various implementations of the 3D keyhole technique. Errors were found to increase with increasing temporal resolution and reduced object size. Errors of 75% are possible for objects with a diameter approaching 1 pixel when a 3D keyhole implementation that samples 50% of phase‐encoding data in each direction is used. Preliminary clinical Images with this approach illustrate artifacts consistent with inadequate k‐space sampling.
Transient increased segmental hepatic enhancement distal to portal vein obstruction on dynamic gadolinium‐enhanced gradient echo MR images
Authors: Schlund James F. , Semelka Richard C. , Kettritz Ute , Eisenberg Lara B. , Lee Joseph K. T.
Published: March 2007

The purpose of the present study was to demonstrate the frequency of occurrence of transient increased segmental hepatic enhancement distal to portal veto obstruction in patients with a lobar (main branch) portal vein obstruction. MR images of all patients with main and lobar branch portal vein obstruction examined by dynamic gadolinium enhanced gradient echo MR images between December 1990 and July 1994 were reviewed retrospectively. All studies included T2‐weighted imaging, Tl‐weighted spoiled gradient echo‘fast low angle shot ([FLASH])’ and postgadolinium enhanced PLASH imaging at 1, 45, and 90 sec and 10 min. Fourteen patients were identified with portal vein obstruction which Included: six with main portal and right and left branch occlusion, six with right lobar, and two with left lobar. In the six patients with main portal vein obstruction, enhancement on 1‐sec postgadolinium FLASH images was homogenous (three patients), diffusely heterogeneous (two patients), or peripherally hyperintense (one patient). In eight of eight patients with isolated obstruction of the right or left lobar portal vein, transient‐increased segmental enhancement distal to portal vein occlusion was observed on immediate postcontrast images. Relatively high signal intensity of the involved segments was present on 1‐sec images and liver parenchymal enhancement became more homogeneous by 45 to 90 sec in all cases. In conclusion, transient‐increased segmental enhancement occurred in eight of eight patients with isolated right or left portal vein occlusion. We postulate that this effect occurs due to increased hepatic arterial blood flow in the presence of portal vein obstruction.
MR‐guided biopsy of the breast after lumpectomy and radiation therapy using two methods of immobilization in the lateral decubitus position
Authors: Desouza Nandita M. , Kormos Donald W. , Krausz T. , Coutts Glyn A. , Hall Alasdair S. , Burl Michael , Schwieso Jane E. , Puni Rakesh , Vernon Claire
Published: March 2007

We describe two methods of breast immobilization using the lateral decubitus position to increase patient comfort and access to the axillary tail for MR‐guided biopsy in the postsurgical or irradiated breast. The First method uses a compression device with good immobilization but poor patient tolerance. The second approach uses a thermoplastic mesh material to form a rigid exoskeleton around the breast: immobilization is adequate and patient acceptability is good. The latter method is prderred and requires formal evaluation in larger scale trials.
Dynamic Evaluation of Exercising Leg Muscle in Healthy Subjects with Echo Planar MR Imaging: Work Rate and Total Work Determine Rate of T2 Change
Authors: Disler David G. , Cohen Mark S. , Krebs David E. , Roy Serge H. , Rosenthal Daniel I.
Published: March 2007

Echo planar MR imaging of the leg was performed in nine healthy volunteers to better understand the dynamic relationship between exercise and changes in muscle T2. Imaging and T2 calculation was performed before, during, and after ankle dorsiflexion exercises using a TR of 9 seconds and a TE of 60 msec. Performing 9‐second duty cycles, six of the subjects exercised for sets of 12 duty cycles, three with a graded series of weights and pulleys and three with an isometric orthotic device graded in varying percentages of maximum voluntary contraction. The other three volunteers performed duty cycles to fatigue. Gastrocnemius and soleus muscle T2 relaxation times were unchanged before, during, and after exercise. The tibialis anterior muscle showed an initial brief 1.7–6.2% decrease in T2 values after starting exercise, followed by a linear increase. Maximum T2 values and percent changes were higher for higher work rates (P <.05), and the rate of T2 change increased in a linear fashion with increasing work rates. By using rapid serial MR imaging, we show that the rate of muscle T2 change bears a simple linear relationship to muscle work. This technique may be exploited in both diagnostic and rehabilitation procedures.
1995 SMR young investigators' award finalist: MR measurement of time‐dependent blood pressure variations
Authors: Urchuk Stephen N. , Plewes Donald B.
Published: March 2007

An MR imaging method for measuring intravascular pressure variations is introduced. The technique is based on estimates of vascular compliance and vessel distension, which are obtained from a correlation of spatial and temporal velocity derivatives and measurements of the velocity gradient in the direction of flow, respectively. The accuracy of the technique was determined in vitro through a comparison of MR and transducer pressure measurements obtained in distensible vessel phantoms undergoing pulsatile flow. Results indicated that a root‐mean‐square error of 4–12% can be expected in phantoms covering a physiological range of compliance. In vivo feasibility was demonstrated by thoracic aorta pressure measurements, which produced pressure waveforms with an expected shape and magnitude.
Fast spin‐echo characteristics of visual stimulation‐induced signal changes in the human brain
Authors: Gao Jia‐Hong , Xiong Jinhu , Li Jinqi , Schiff Joseph , Roby John , Lancaster Jack L. , Fox Peter T.
Published: March 2007

A fast spin‐echo (FSE) technique used in a conventional MR imaging scanner has been successfully developed for obtaining functional MR images with high spatial resolution and multiple slices. Our preliminary visual stimulation studies using the FSE technique show that the nuclear MR signal increases by 2.6% during activation in the primary visual cortex. These results provide evidence that the diffusion of tissue water molecules plays a key role in determining functional MR signal amplitude. Because the FSE functional MR imaging signal is extremely sensitive to microvascular (brain capillaries) hemodynamics, the FSE technique can be a powerful tool for studying the neuronal activity of the human brain.
Studies of the central nervous system‐derived CAD cell line, a suitable model for intraneuronal transport studies?
Authors: Li Yongling , Hou Linda Xiu‐E , Aktiv Annika , Dahlström Annica
Published: March 2007

The CAD cell line is a variant of a CNS‐derived Cath.a cell line established by targeted oncogenesis in transgenic mice. Cell differentiation of the cell line can be induced by “starvation,” i.e., removal of serum from the culture medium (protein‐free medium). The differentiated CAD cells extend long processes, which ultrastructurally contain abundant microtubules, intermediate filaments, and various synaptic vesicles/organelles in the varicose enlargements, thus resembling neurites. Histochemical studies demonstrated that the differentiated cells express a number of synaptic vesicle proteins, cytoskeletons, different neurotransmitter enzymes, neuropeptides, and glia proteins. The data suggest that the differentiated CAD cells may be a suitable model for studies of intraneuronal transport, recycling of receptors, and pharmacological investigations. © 2007 Wiley‐Liss, Inc.
Roles of glial p75NTR in axonal regeneration
Authors: Zhou Xin‐Fu , Li Hong‐Yun
Published: March 2007

The neurotrophin receptor p75 (p75NTR) is expressed by both neurons and glia. Nerve injury triggers up‐regulation of p75NTR in Schwann cells (SC) but not in central glia. In contrast to neuronal p75NTR, which mediates negative signals from myelin‐associated proteins resulting in neurite collapse, glial p75NTR may play a positive role in nerve regeneration by forming neurotrophin chemoattractant gradients or by competitively antagonizing the NOGO/NgR/LINGO‐1 signal through cell–cell contact or regulated intramembranous proteolysis (RIP) of p75NTR. This piece presents some recent evidence supporting this hypothesis. © 2007 Wiley‐Liss, Inc.
S/P and T/P phosphorylation is critical for tau neurotoxicity in Drosophila
Authors: Steinhilb Michelle L. , Dias‐Santagata Dora , Mulkearns Erin E. , Shulman Joshua M. , Biernat Jacek , Mandelkow Eva‐Maria , Feany Mel B.
Published: March 2007

The microtubule‐associated protein tau is hyperphosphorylated abnormally in AD and related neurodegenerative disorders. Many phospho epitopes created by proline directed kinases (SP/TP sites) show relative specificity for disease states. To test whether phosphorylation at the disease‐associated SP/TP sites affects tau toxicity in vivo, we expressed a form of tau in Drosophila in which all SP/TP sites are mutated to alanine. We find that blocking phosphorylation at SP/TP motifs markedly reduces tau toxicity in vivo. Using phosphorylation‐specific antibodies, we identify a positive correlation between increased phosphorylation at disease‐associated sites and neurotoxicity. We use the phosphorylation‐incompetent version of tau to show that kinase and phosphatase modifiers of tau neurotoxicity, including cdk5/p35, the JNK kinase hemipterous and PP2A act via SP/TP phosphorylation sites. We provide direct evidence in an animal model system to support the role of phosphorylation at SP/TP sites in playing a critical role in tau neurotoxicity. © 2007 Wiley‐Liss, Inc.
Neuregulins at the neuromuscular synapse: Past, present, and future
Authors: Rimer Mendell
Published: March 2007

At the developing vertebrate neuromuscular junction, neuregulins are growth/differentiation factors essential for terminal Schwann cell survival. Neuregulins have also been thought as the critical signals responsible for the increased transcription of acetylcholine receptor subunit genes at the neuromuscular synapse. This latter role is now highly controversial. This article reviews the evidence that has shaped the views of the neuregulins and how these views have been challenged. The most recent experiments indicate that neuregulin signaling to postsynaptic muscle fibers may modulate, rather than determine, acetylcholine receptor expression at the neuromuscular junction. Based on findings from my lab and those of others, I propose that this modulation might involve novel posttranscriptional molecular mechanisms. Finally, I also suggest that neuregulin signaling may have an important role to play in mediating the response of adult terminal Schwann cells to denervation. © 2007 Wiley‐Liss, Inc.
John Hunter and the origins of modern orthopaedic research
Authors: Evans Christopher H.
Published: March 2007

Orthopaedic research is a multi‐disciplinary, eclectic pursuit conducted in a scientific manner. John Hunter (1728–1793), the Founder of Scientific Surgery, was the first to engage systematically in this enterprise. Born in Scotland, Hunter moved to London to help his brother, William, run an anatomy school. This involved both the procurement and dissection of cadavers, for which activities John showed great aptitude. Further training and a spell as an army surgeon equipped him for his life's work as a practitioner, researcher and teacher. Hunter amassed an enormous collection of specimens displayed in a specially designed house he constructed in Leicester Square, and maintained an extensive menagerie and additional laboratories in Earl's Court. Many of his specimens are now housed in the Hunterian Museum of the Royal College of Surgeons in London. Among Hunter's contributions to orthopaedics are his discovery of bone remodeling, and his studies on the repair and regeneration of bone, cartilage and tendon. He developed numerous new surgical procedures, and provided detailed anatomical descriptions that often corrected received wisdom. Many of his pupils became famous in their own right and two of them founded the USA's first medical school. John Hunter died of a heart attack brought on by hospital administrators. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:556–560, 2007
The extraction of beef bones with water, dilute sodium hydroxide and dilute potassium chloride
Authors: Duerr Peter E. , Earle Mary D.
Published: March 2007

To investigate the recovery of waste meat on bones, crushed beef bones were extracted under various conditions within a temperature range of 50 to 125 ºC and a pH range of 6.3 to 11.6. The extracts were analysed for total solids, collagen, non‐collagen protein, non‐protein nitrogen, creatinine and ash. The water extraction of collagen increased and of non‐collagen protein decreased with increases in temperature up to 100 ºC and the total yield of protein markedly increased with alkaline pH.
Effect of the size of hay particles on digestion in the sheep
Authors: Alwash A. H. , Thomas P. C.
Published: March 2007

Four sheep fitted with permanent rumen cannulae were used to study the digestion of a hay diet prepared, by grinding, in four forms differing in particle size. Each form of the diet was given at two levels of feeding, 1.1 and 2.4 times the energy requirement for maintenance of bodyweight. At each level, the digestibility of organic matter and of other constituents in the diet and the mean retention time of food residues in the alimentary tract decreased from the coarsest to the most finely ground form of hay. The digestibility of organic matter (D) was related to the mean particle size (in nm) in the diet (p) such that D = 57.5 + 16.97 p2 (P < 0.001) at the low level of feeding and D = 51.5 + 23.75 p2 (P < 0.001) at the high level. There were corresponding relationships for the mean retention time of food residues (R) such that R = 69.1 + 64.0p2 (P < 0.01) and R = 49.6 + 50.2p2 (P < 0.01). There were no marked variations with the form of the hay in the rate of digestion of hay in nylon bags, or cotton threads, suspended in the rumen or in the pH or concentrations of ammonia or total or individual short‐chain fatty acids in the rumen fluid.

It is suggested that changes in digestion associated with the provisions of forages in ground forms can be related to the size of particles in the ground food and the level at which it is fed.
Effect of environmental temperature on the degree of unsaturation of depot fats of pigs given different amounts of food
Authors: Fuller M. F. , Duncan W. R. H. , Boyne A. W.
Published: March 2007

Measurements were made of the iodine value (IV) of fat from seven sites on pigs which had been kept at 5, 13 or 23 ºC during their growth from 20 to 90 kg. At each temperature the pigs were given one of three levels of daily food intake.

The IV of the outer back fat exceeded that of the inner by 7.7 units at the shoulder, 6.8 units at the midback and 2.4 units at the rump.

Increasing daily food intake significantly depressed the IV of fat only at the shoulder sites.

The IV of fat at all sites fell with increasing temperature by an amount ranging from 0.22 units per 1 ºC at the midback to 0.55 units per 1 ºC in the inner shoulder fat. The IV of perinephric fat fell by 0.39 units per 1 ºC increase in temperature; that this fat was thus affected suggests that the effect of environmental temperature on fat composition is not conditioned by its effect on local tissue temperature.

It was calculated that these effects arose largely by changes in the proportions of fatty acids synthesized de novo; the exogenous fat consumed could have made only a small contribution.