bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of R2 with total iron concentration in the brains of rhesus monkeys
Authors: Hardy Peter A. , Gash Don , Yokel Robert , Andersen Anders , Ai Yi , Zhang Zhiming
Published: January 2005

Purpose

To estimate the relationship between R2 = 1/T2 as measured with a double echo spin echo sequence and total iron concentration in gray matter structures in the brains of aging rhesus monkeys.

Materials and Methods

Using a 1.5‐T magnetic resonance (MR) imager, we collected double echo spin echo images of the brains of 12 female rhesus monkeys aged between 9 and 23 years. From the double echo images, the transverse relaxation rate R2 = 1/T2 was calculated in selected gray matter regions. After the animals were euthanized, their brains were excised and tissue punches were taken of the substantia nigra, globus pallidus, and gray matter regions of the cerebellum. Some of the tissue punches were assayed for total iron using atomic absorption spectroscopy.

Results

The range of tissue iron concentration spanned from 15 to 450 μg/g wet weight, with the highest levels in the globus pallidus and the lowest levels in the cerebellum. The results show that R2 was highly correlated with the total iron concentration and that the relationship between R2 and tissue iron concentration appeared to depend upon the iron concentration. For concentrations above approximately 150 μg/g wet weight, R2 increased with a sensitivity of 0.0484 ± 0.0023 second−1(μg/g)−1. In contrast, where the iron concentration was below 150 μg/g, R2 increased at 0.0013 ± 0.0073 second−1(μg/g)−1. The bilinear behavior may reflect changes with age in the relative amounts of iron distributed diffusely and in granular form in the globus pallidus and substantia nigra. Histological sections of the tissues stained for iron and ferritin support this hypothesis and indicate that the distribution of ferritin is similar to the distribution of iron.

Conclusion

This study reaffirms the value of measuring the MR relaxation rate R2 for a noninvasive estimate of iron content in the brain and identified limitations in the relationship at low tissue iron concentrations. J. Magn. Reson. Imaging 2005;21:118–127. © 2005 Wiley‐Liss, Inc.
Central brightening due to constructive interference with, without, and despite dielectric resonance
Authors: Collins Christopher M. , Liu Wanzhan , Schreiber Weston , Yang Qing X. , Smith Michael B.
Published: January 2005

Purpose

To aid in discussion about the mechanism for central brightening in high field magnetic resonance imaging (MRI), especially regarding the appropriateness of using the term dielectric resonance to describe the central brightening seen in images of the human head.

Materials and Methods

We present both numerical calculations and experimental images at 3 T of a 35‐cm‐diameter spherical phantom of varying salinity both with one surface coil and with two surface coils on opposite sides, and further numerical calculations at frequencies corresponding to dielectric resonances for the sphere.

Results

With two strategically placed surface coils it is possible to create central brightening even when one coil alone excites an image intensity pattern either bright on one side only or bright on both sides with central darkening. This central brightening can be created with strategic coil placement even when the resonant pattern would favor central darkening. Results in a conductive sample show that central brightening can similarly be achieved in weakly conductive dielectric materials where any true resonances would be heavily damped, such as in human tissues.

Conclusion

Constructive interference and wavelength effects are likely bigger contributors to central brightening in MR images of weakly conductive biological samples than is true dielectric resonance. J. Magn. Reson. Imaging 2005;21:192–196. © 2005 Wiley‐Liss, Inc.
A modified projection reconstruction trajectory for reduction of undersampling artifacts
Authors: Wang Wen‐Tung , Grimm Roger C. , Riederer Stephen J.
Published: January 2005

Purpose

To reduce undersampling artifacts for a given number of repetitions of the projection reconstruction (PR) sequence by modifying its k‐space trajectory to sample more mid‐frequencies while reducing the sampling coverage of the peripheral spatial frequencies.

Materials and Methods

The single k‐space spoke measured per repetition in the standard PR was modified so that one complete and two partial spokes were measured per repetition but with decreased k‐space extent. The point spread functions (PSFs) and undersampling artifacts of the modified PR were compared with those of the standard PR for various numbers of projections. Phantom and in vivo images were used to assess the relative performance.

Results

PSF analysis indicated that the modified PR method provided reduced undersampling artifacts with somewhat reduced spatial resolution. The phantom and in vivo images corroborated this.

Conclusion

The modified PR trajectory provides reduced undersampling artifact vs. the standard PR, particularly when the number of projections is limited and the artifact level is high. J. Magn. Reson. Imaging 2005;21:179–186. © 2005 Wiley‐Liss, Inc.
Interstudy reproducibility of three‐dimensional volume‐selective fast spin echo magnetic resonance for quantifying carotid artery wall volume
Authors: Varghese Anitha , Crowe Lindsey A. , Mohiaddin Raad H. , Gatehouse Peter D. , Yang Guang Zhong , Nott David M. , McCall James M. , Firmin David N. , Pennell Dudley J.
Published: January 2005

Purpose

To assess the interstudy reproducibility of a three‐dimensional volume‐selective, fast spin echo (FSE) magnetic resonance technique for the assessment of carotid artery wall volume, which is a marker for total carotid plaque volume.

Materials and Methods

Interstudy reproducibility was evaluated in 10 subjects with evidence of carotid artery atherosclerotic disease on carotid Doppler ultrasonography. Subjects were scanned twice with an interscan time of one hour to four days. The carotid artery was imaged in cross‐section, and the total carotid arterial wall volume (TWV) was calculated by subtraction of the total carotid lumen volume from the total outer carotid vessel volume.

Results

The mean carotid TWV for the scans was 741 and 734 mm3, respectively, with no significant difference (mean difference 7 mm3; P = 0.5). The time for each study was approximately 20 minutes. The standard deviation of the differences between the measurements was 33 mm3, yielding an interstudy coefficient of variation of 4.4%. Sample size calculations showed that 16 patients would enable this difference in plaque volume over time to be detected with 80% power at a P value of 0.05.

Conclusion

Volumetric analysis with CMR of carotid artery plaques using a three‐dimensional volume‐selective FSE is efficient with good interstudy reproducibility, and is well suited for longitudinal studies of progression of carotid atheroma with reasonable sample sizes. J. Magn. Reson. Imaging 2005;21:187–191. © 2005 Wiley‐Liss, Inc.
Coronary arteries at 3.0 T: Contrast‐enhanced magnetization‐prepared three‐dimensional breathhold MR angiography
Authors: Bi Xiaoming , Li Debiao
Published: January 2005

Purpose

To evaluate the efficacy of contrast‐enhanced coronary magnetic resonance angiography (MRA) at 3.0 T.

Materials and Methods

Nine healthy human volunteers were studied on a 3.0‐T whole‐body MR system. A three‐dimensional, breathhold, magnetization‐prepared, segmented, gradient‐echo sequence was used, with injection of 20 mL gadopentetate dimeglumine for each three‐dimensional slab. Imaging parameters were optimized based on computer simulations. Signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), depicted coronary artery length, lumen diameter, and imaging sharpness with contrast agent were evaluated. SNR and CNR were compared to the results from a previous 1.5‐T study.

Results

A 53% increment in SNR and a 305% enhancement in CNR were measured with contrast. Vessel length and sharpness depicted were higher and the lumen diameter was lower (all P values < 0.05) in postcontrast images. Compared to previous results from 1.5‐T, the SNR, CNR, and vessel sharpness were enhanced at 3.0 T with higher spatial resolution.

Conclusion

Contrast‐enhanced, three‐dimensional, coronary MRA at 3.0 T is a promising technique for diagnosing coronary artery diseases. Patient studies are necessary to evaluate its clinical utility. J. Magn. Reson. Imaging 2005;21:133–139. © 2005 Wiley‐Liss, Inc.
The comparison of detailed chemical kinetic mechanisms; forward versus reverse rates with CHEMRev
Authors: Rolland Sébastien , Simmie John M.
Published: January 2005

The computation of the reverse rate of an elementary reaction given the forward rate and requisite thermodynamic data is well established. Nevertheless the procedure is extremely laborious and error prone, in particular, when large numbers of such calculations must be performed and the results fitted to traditional or extended forms of the Arrhenius rate constant equation. We have developed a software application, CHEMRev, which automatically performs such computations for Chemkin‐style reaction mechanisms. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 119–125, 2005
Kinetic studies of the reactions of pentacyanoferrate(III) complexes with L‐ascorbic acid
Authors: Lin Lu‐Ming , Lien Ming‐Huei , Yeh Andrew
Published: January 2005

The reduction of Fe(CN)5L2− (L = pyridine, isonicotinamide, 4,4′‐bipyridine) complexes by ascorbic acid has been subjected to a detailed kinetic study in the range of pH 1–7.5. The rate law of the reaction is interpreted as a rate determining reaction between Fe(III) complexes and the ascorbic acid in the form of H2A(k0), HA−(k1), and A2− (k2), depending on the pH of the solution, followed by a rapid scavenge of the ascorbic acid radicals by Fe(III) complex. With given Ka1 and Ka2, the rate constants are k0 = 1.8, 7.0, and 4.4 M−1 s−1; k1 = 2.4 × 103, 5.8 × 103, and 5.3 × 103 M−1 s−1; k2 = 6.5 × 108, 8.8 × 108, and 7.9 × 108 M−1 s−1 for L = py, isn, and bpy, respectively, at μ = 0.10 M HClO4/LiClO4, T = 25°C. The kinetic results are compatible with the Marcus prediction. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 126–133, 2005
Photophysics and kinetics of naphthopyran derivatives, part 1: General analytical solutions for the kinetics of AB(k,ϕ) and ABC(k,ϕ) systems
Authors: Maafi Mounir , Brown Robert G.
Published: January 2005

A new formalism allowing solution of the differential equations for kinetic systems comprising three species (ABC) linked by first‐order thermal and/or photochemical reactions is proposed. The approach is developed specifically with photochromic materials in mind, but the formalism developed is shown to be applicable to a variety of kinetic systems irradiated with monochromatic light where the photokinetic factor (F) is constant. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 162–174, 2005
Autopoisoning reactions over rough surface: A multifractal scaling analysis
Authors: Chaudhari Ajay , Yan Ching‐Cher Sanders , Lee Shyi‐Long
Published: January 2005

The effect of surface roughness and number of reaction event on the decay type diffusion limited reaction (DLR) over rough surface of random deposition model was studied to examine the surface morphological effect on the surface reaction. Effect of decay profiles on the reaction probability distribution (RPD) of the reaction was then analyzed with multifractal scaling techniques. The dynamics of these autopoisoning reactions is controlled by the two parameters, namely, the initial sticking probability (Pini) of every site and the decay rate (m). More the rough surface, less are the number of active sites and wider is the distribution of reaction probability. More the number of reaction events, more are the number of active sites and more is the homogeneity in the RPD. The q‐τ(q) multifractal curves are found to be nonlinear for all the cases which give wide range of α values in α‐f(α) multifractal spectrum. Smaller the decay rate, narrower is the range of α values. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 175–182, 2005
Rate constants for the gas‐phase reactions of O3with a series of cycloalkenes at 296 ± 2 K
Authors: Cusick Roland D. , Atkinson Roger
Published: January 2005

Using a relative rate method, rate constants for the gas phase reactions of O3with 1‐ and 3‐methylcyclopentene, 1‐, 3‐, and 4‐methylcyclohexene, 1‐methylcycloheptene,cis‐cyclooctene, 1‐ and 3‐methylcyclooctene, 1,3‐ and 1,5‐cyclooctadiene, and 1,3,5,7‐cyclooctatetraene have been measured at 296 ± 2 K and atmospheric pressure of air. The rate constants obtained (in units of 10−18cm3molecule−1s−1) are 1‐methylcyclopentene, 832 ± 24; 3‐methylcyclopentene, 334 ± 12; 1‐methylcyclohexene, 146 ± 10; 3‐methylcyclohexene, 55.3 ± 2.6; 4‐methylcyclohexene, 73.1 ± 3.6; 1‐methylcycloheptene, 930 ± 24;cis‐cyclooctene, 386 ± 23; 1‐methylcyclooctene, 1420 ± 100; 3‐methylcyclooctene, 139 ± 9;cis,cis‐1,3‐cyclooctadiene, 20.0 ± 1.4; 1,5‐cyclooctadiene, 152 ± 10; and 1,3,5,7‐cyclooctatetraene, 2.60 ± 0.19, where the indicated errors are two least‐squares standard deviations and do not include the uncertainties in the rate constants for the reference alkenes (propene, 1‐butene,cis‐2‐butene,trans‐2‐butene, 2‐methyl‐2‐butene, and terpinolene). These rate data are compared with the few available literature data, and the effects of methyl substitution discussed. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 183–190, 2005
Presence of multiple bile ducts in the liver graft increases the incidence of biliary complications in pediatric liver transplantation
Authors: Salvalaggio Paolo R.O. , Whitington Peter F. , Alonso Estella M. , Superina Riccardo A.
Published: January 2005

We studied the impact of multiple bile duct anastomosis on the development of biliary complications after liver transplantation in children. A total of 101 patients received a primary liver transplant and were divided into 2 groups: those with a single bile duct (n = 77) and those with multiple bile ducts (n = 24). Mean follow-up was 39.8 ± 20.8 months. A total of 27 patients presented with biliary complications (26.7%), 18 patients (18.7%) presented with early complications (12 leaks and 6 strictures), and 9 patients (8.9%) had late strictures. Hepatic artery thrombosis (HAT) and multiple bile ducts were significant risk factors for the development of biliary complications, and the presence of multiple bile ducts was an independent risk factor. Patients with multiple bile ducts had a significantly greater incidence of total biliary complications compared to those with single ducts. Patients with multiple ducts had a higher incidence of leaks when compared to those in the single duct group, but the incidence of strictures, both early and late, was similar in both groups. One-year patient and graft survivals were not statistically different in the 2 groups. In conclusion, the presence of more than one bile duct in the graft is an independent risk factor for the development of biliary complications after pediatric liver transplantation. (Liver Transpl 2005;11:161–166.)
Liver transplantation with simultaneous removal of an intracardiac transjugular intrahepatic portosystemic shunt and a vena cava filter without the utilization of cardiopulmonary bypass
Authors: Salvalaggio Paolo R.O. , Koffron Alan J. , Fryer Jonathan P. , Abecassis Michael M.
Published: January 2005

Transjugular intrahepatic shunts (TIPSs) are widely used in the management of portal hypertension complications including variceal bleeding, refractory ascites, and hepatic hydrothorax. Vena cava filters (VCFs) are an important therapeutic modality in the prevention of pulmonary emboli in patients suffering deep venous thrombosis and clinical contraindications for anticoagulation. Stent and filter misplacement or migration may occur, complicating liver transplantation (LT) surgery. We describe the intraoperative management of a patient with cirrhosis, who had a TIPS extending into the right atrium (RA) and a retrohepatic VCF. Stent and filter removals were deferred until the time of LT. Both procedures were performed successfully by complete cava and portal reconstruction. In conclusion, careful assessment and surgical management of patients with stent and filters permits successful LT. (Liver Transpl 2005;11:229–232.)
Negative impact of systemic catecholamine administration on hepatic blood perfusion after porcine liver transplantation
Authors: Mehrabi Arianeb , Golling Markus , Kashfi Arash , Boucsein Tamara , Schemmer Peter , Gutt Carsten N. , Schmidt Jan , Büchler Markus W. , Kraus Thomas W.
Published: January 2005

Catecholamines are often administered during and after liver transplantation (LTx) to support systemic perfusion and to increase organ oxygen supply. Some vasoactive agents can compromise visceral organ perfusion. We followed the hypothesis that the vasculature of transplanted livers presents with a higher sensitivity, which leads to an increased vulnerability for flow derangement after application of epinephrine (Epi) or norepinephrine (NorEpi). Hepatic macroperfusion and microperfusion during systemic Epi or NorEpi infusion were measured by Doppler flow and thermodiffusion probes in porcine native, denervated, and transplanted livers (n = 16 in each group). Epi or NorEpi were infused (n = 8 in each subgroup) in predefined dosages (low dose = 5 μg/kg/minute and high dose = 10 μg/kg/minute) over 240 minutes. Systemic cardiocirculatory parameters were monitored continuously. Hepatic perfusion data were compared between all groups at comparable time points and dosages. In all native, denervated, and transplanted liver groups, Epi and NorEpi induced an inconsistent rise of mean arterial pressure and heart rate shortly after onset of infusion in both dosages compared with baseline. No significant differences of cardiovascular parameters at comparable time points were observed. In native livers, Epi and NorEpi induced only temporary alterations of hepatic macrocirculation and microcirculation, which returned to baseline 2 hours after onset of infusion. No significant alterations of hepatic blood flow were detected after isolated surgical denervation of the liver. By contrast, transplanted livers showed a progressive decline of hepatic macrocirculation (33–75% reduction) and microcirculation (39–58% reduction) during catecholamine infusions in a dose-dependent fashion. Characteristics of liver blood flow impairment were comparable for both vasoactive agents. In conclusion, pronounced disturbances of hepatic macrocirculation and microcirculation were observed during systemic Epi and NorEpi infusion after LTx compared with native and denervated livers. Microcirculation disturbances after LTx might be explained by impairment of hepatic blood flow regulation caused by an increased sensitivity of hepatic vasculature after ischemia-reperfusion and by lengthening of vasopressor effects caused by reduced hepatocyte metabolism. Clinicians should be aware of this potentially hazardous effect. Therefore, application of catecholamines after clinical LTx should be indicated carefully. (Liver Transpl 2005;11:174–187.)
Ischemic preconditioning in deceased donor liver transplantation: A prospective randomized clinical trial of safety and efficacy
Authors: Koneru Baburao , Fisher Adrian , He Yan , Klein Kenneth M. , Skurnick Joan , Wilson Dorian J. , de la Torre Andrew N. , Merchant Anand , Arora Rakesh , Samanta Arun K.
Published: January 2005

Ischemic preconditioning (IPC) has the potential to decrease graft injury and morbidity after liver transplantation. We prospectively investigated the safety and efficacy of 5 minutes of IPC induced by hilar clamping in local deceased donor livers randomized 1 : 1 to standard (STD) recovery (N = 28) or IPC (N = 34). Safety was assessed by measurement of heart rate, blood pressure, and visual inspection of abdominal organs during recovery, and efficacy by recipient aminotransferases (aspartate aminotransferase [AST] and alanine aminotransferase [ALT], both measured in U/L), total bilirubin, and international normalized ratio of prothrombin time (INR) after transplantation. IPC performed soon after laparotomy did not cause hemodynamic instability or visceral congestion. Recipient median AST, median ALT, and mean INR, in STD vs. IPC were as follows: day 1 AST 696 vs. 841 U/L; day 3 AST 183 vs. 183 U/L; day 1 ALT 444 vs. 764 U/L; day 3 ALT 421 vs. 463 U/L; day 1 INR 1.7 ± .4 vs. 2.0 ± .8; and day 3 INR 1.3 ± .2 vs. 1.4 ± .3; all

P

> .05. No instances of nonfunction occurred. The 6-month graft and patient survival STD vs. IPC were 82 vs. 91% and median hospital stay was 10 vs. 8 days; both

P

> .05. In conclusion, deceased donor livers tolerated 5 minutes of hilar clamping well, but IPC did not decrease graft injury. Further trials with longer periods of preconditioning such as 10 minutes are needed. (Liver Transpl 2005;11:196–206.)
Colonization with methicillin-resistant Staphylococcus aureus after liver transplantation
Authors: Santoro-Lopes Guilherme , de Gouvêa Érika Ferraz , Monteiro Rodrigo Carreira M. , Branco Rodrigo Castelo , Rocco José Rodolfo , Halpern Márcia , Ferreira Adriana Lúcia Pires , de Araújo Elaine Gama Pessoa , Basto Samanta T. , Silveira Vinicius Gomes , Ribeiro-Filho Joaquim
Published: January 2005

Methicillin-resistant

Staphylococcus aureus

(MRSA) is a frequent cause of infection after orthotopic liver transplantation (OLT). Colonization with MRSA is associated with a higher risk of infection. Previous studies have shown a high prevalence of MRSA colonization among OLT candidates. However, the risk of colonization with MRSA after OLT is still unclear. The objective of this study was to estimate the incidence and the factors associated with colonization with MRSA after OLT. This was a prospective cohort study including patients submitted to OLT between the years 2000 and 2002. Surveillance cultures of nasal swab specimens were performed within the 1st 72 hours of hospital admission and, subsequently, on weeks 2, 6, 13, and 26. Patients whose baseline cultures revealed nasal carriage of MRSA were excluded. A total of 60 patients were included in the study. The median follow-up was 72 days. A total of 9 patients (15%) became colonized. In multiple logistic regression analyses, the use of a urinary catheter for ≥5 days (

P

= .006), postoperative bleeding at the surgical site (

P

= .009), and preoperative use of fluoroquinolones (

P

= .08) were associated with a higher risk of colonization. Patients without any of these risk factors did not become colonized. In conclusion, nasal carriage of MRSA is frequently acquired after OLT. Periodic postoperative screening for MRSA carriage should be an integral component in programs designed to reduce nosocomial MRSA transmission in these patients. Further studies are needed to set up and validate a predictive model that could allow targeting postoperative screening to high-risk OLT recipients. (Liver Transpl 2005;11:203–209.)
Preharvest donor hyperoxia predicts good early graft function and longer graft survival after liver transplantation
Authors: Corradini Stefano Ginanni , Elisei Walter , De Marco Rosanna , Siciliano Maria , Iappelli Massimo , Pugliese Francesco , Ruberto Franco , Nudo Francesco , Pretagostini Renzo , Bussotti Alessandro , Mennini Gianluca , Eramo Annarita , Liguori Francesca , Merli Manuela , Attili Adolfo Francesco , Muda Andrea Onetti , Natalizi Stefania , Berloco Pasquale , Rossi Massimo
Published: January 2005

A total of 44 donor/recipient perioperative and intraoperative variables were prospectively analyzed in 89 deceased-donor liver transplantations classified as initial good graft function (IGGF) or initial poor graft function (IPGF) according to a scoring system based on values obtained during the 1st 72 postoperative hours from the serum alanine aminotransferase (ALT) concentration, bile output, and prothrombin activity. The IGGF compared with the IPGF group showed: 1) longer graft (

P

= .002) and patient (

P

= .0004) survival; 2) at univariate analysis, a higher (mean [95% confidence interval]) preharvest donor arterial partial pressure of oxygen (PaO2) (152 [136–168] and 104 [91–118] mmHg, respectively;

P

= .0008) and arterial hemoglobin oxygen saturation (97.9 [97.2–98.7] and 96.7 [95.4–98.0]%, respectively;

P

= .0096), a lower percentage of donors older than 65 years (13 and 33%, respectively;

P

= .024), a lower percentage of donors treated with noradrenaline (16 and 41%, respectively;

P

= .012). At multivariate analysis, IGGF was associated positively with donor PaO2 and negatively with donor age greater than 65 years and with donor treatment with noradrenaline. Independently from the grouping according to initial graft function, graft survival was longer when donor PaO2 was >150 mmHg than when donor PaO2 was ≤150 mmHg (

P

= .045). In conclusion, preharvest donor hyperoxia predicts IGGF and longer graft survival. (Liver Transpl 2005;11:140–151.)
The hepatic regeneration power of mild steatotic grafts is not impaired in living-donor liver transplantation
Authors: Cho Jai Young , Suh Kyung-Suk , Kwon Choon Hyuck , Yi Nam-Joon , Cho Soo Youn , Jang Ja-June , Kim Se Hyung , Lee Kuhn Uk
Published: January 2005

The aim of this study was to assess histologic changes in steatotic grafts, regenerative capacity, and the outcome of steatotic grafts in living-donor liver transplantation (LDLT). Between September 2002 and February 2004, 55 cases of LDLT with a liver biopsy performed on the 10th postoperative day were enrolled. Patients were grouped according to the intraoperative histologic degree of macrovesicular steatosis (MaS) as follows: Group 1, <5% (n = 24); Group 2, 5 to 15% (n = 24); and Group 3, 15 to 30% (n = 7). The intraoperative microscopic findings and the findings on the 10th postoperative day were compared. Immunohistochemistry was performed using antibody of proliferating cell nuclear antigen (PCNA) and Ki-67 to assess the regeneration power of grafts on the 10th postoperative day. The histologic degree of MaS on postoperative day 10 decreased from 5.22 ± 1.04% (mean ± standard deviation) to 2.17 ± 1.90 in Group 2 (

P

< .001) and from 21.4 ± 8.02 to 4.43 ± 2.70 in Group 3 (

P

= .003). The number of positively stained hepatocytes in 10 high power fields was 48.0 ± 17.1, 53.8 ± 14.4, and 51.5 ± 4.1 in each group by PCNA (

P

= .681), and 24.0 ± 14.0, 25.5 ± 11.8, and 21.6 ± 6.8 by Ki-67 (

P

= .825), respectively. No primary graft nonfunction (PNF) or delayed graft function (DGF) occurred. Major complications were comparable among groups. In conclusion, in LDLT, steatosis disappeared immediately after transplantation and hepatic regeneration power was not impaired in grafts with less than 30% of MaS. Furthermore, a mildly steatotic graft did not increase the risk of graft dysfunction or morbidity in LDLT. (Liver Transpl 2005;11:210–217.)
Compression of the brachial plexus during right lobe liver donation as a cause of brachial plexus injury: A case report
Authors: Dulitz Michael G. , De Wolf Andre M. , Wong Hak , Wray Chris , Sherwani Saadia , Herborn Josh , Sufit Robert L. , Koffron Alan J.
Published: January 2005

We present a case of brachial plexus injury in a living-related liver donor, most likely caused by compression of the plexus between the 1st rib and clavicle, the result of rib retraction for surgical exposure. (Liver Transpl 2005;11:233–235.)
Transmission of West Nile virus by organ transplantation
Authors: Kusne Shimon , Smilack Jerry
Published: January 2005

Abstract

Background

In August 2002, fever and mental-status changes developed in recipients of organs from a common donor. Transmission of West Nile virus through organ transplantation was suspected.

Methods

We reviewed medical records, conducted interviews, and collected blood and tissue samples for testing with a variety of assays. Persons who donated blood to the organ donor and associated blood components were identified and tested for West Nile virus.

Results

We identified West Nile virus infection in the organ donor and in all four organ recipients. Encephalitis developed in three of the organ recipients, and febrile illness developed in one. Three recipients became seropositive for West Nile virus IgM antibody; the fourth recipient had brain tissue that was positive for West Nile virus by isolation and nucleic acid and antigen assays. Serum specimens obtained from the organ donor before and immediately after blood transfusions showed no evidence of West Nile virus; however, serum and plasma samples obtained at the time of organ recovery were positive on viral nucleic acid testing and viral culture. The organ donor had received blood transfusions from 63 donors. A review of blood donors and follow-up testing identified one donor who had viremia at the time of donation and who became seropositive for West Nile virus IgM antibodies during the next two months.

Conclusions

Our investigation of this cluster documents the transmission of West Nile virus by organ transplantation. Organ recipients receiving immunosuppressive drugs may be at high risk for severe disease after West Nile virus infection. Blood transfusion was the probable source of the West Nile virus viremia in the organ donor. (N Engl J Med 2003;348:2196–2203).
Long-term outcome of pediatric liver transplantation for biliary atresia: A 10-year follow-up in a single center
Authors: Fouquet Virginie , Alves Arnaud , Branchereau Sophie , Grabar Sophie , Debray Dominique , Jacquemin Emmanuel , Devictor Denis , Durand Philippe , Baujard Catherine , Fabre Monique , Pariente Danielle , Chardot Christophe , Dousset Bertrand , Massault Pierre-Philippe , Bernard Denis , Houssin Didier , Bernard Olivier , Gauthier Frédéric , Soubrane Olivier
Published: January 2005

The aim of this study was to review our experience in orthotopic liver transplantation (OLT) for biliary atresia (BA) in children and analyze the survival and prognostic factors, and long-term outcome. We reviewed 332 OLTs performed in 280 children between the years 1986 and 2000. Univariate and multivariate analysis were performed on patient and graft survivals according to recipients' and donors' characteristics as well as intraoperative data. The long-term outcome among the 80 children living at 10 years after OLT was studied according to growth, immunosuppressive therapy, and liver and renal functions. Liver graft status was eventually documented by liver biopsy. Status of rehabilitation was assessed by reviewing school performance and employment. Overall patient survival rates at 1, 5, and 10 years were 85, 82, and 82%, respectively, and the corresponding overall graft survival rates were 77, 73, and 71%. In the multivariate analysis, we identified 4 independent prognostic factors: polysplenia syndrome (

P

= .03), United Network for Organ Sharing (UNOS) status (

P

= .05), donor's age (

P

= .01), and perioperative surgical complications (

P

= .03). At 10 years after transplant, 80 children were alive and had normal growth rates. Liver histology was abnormal in 73% of these long-term survivors, mainly due to chronic rejection and centrilobular fibrosis. A total of 63 of the 80 children attended normal school and in 55 children (69%) school performance was not delayed. In conclusion, we discovered that a good long-term survival could be achieved after liver transplantation for BA, with a 82% survival rate at 10 years with normal scholastic studies in the majority of recipients. (Liver Transpl 2005;11:152–160.)
Calculating NMR paramagnetic relaxation enhancements without adjustable parameters: the spin‐3/2 complex Cr(III)(AcAc)3
Authors: Miller Jeremy , Schaefle Nathaniel , Sharp Robert
Published: January 2005

NMR paramagnetic relaxation enhancement (NMR‐PRE) produced by the electron spin S = 3/2 complex Cr(III)(acac)3 (acac = acetylacetonato) has been simulated by spin dynamic (SD) simulation methods in order to test current theory of NMR‐PRE. This system provides a particularly demanding test of theory, since the Zeeman and zero field splitting (zfs) contributions to the electron spin Hamiltonian are of comparable magnitude in the range of magnetic field variation of the data, and Brownian reorientation of both the zfs tensor and the interspin vector play important roles in the relaxation mechanism. For Cr(III)(acac)3, all of the sensitive parameters of theory were known from independent experiments, so that a calculation was possible without variation of parameters. The R1 field dispersion profile (fdp), reported by Wang et al. (J. Magn. Reson. 1987; 73: 277), exhibit a single pronounced dispersive feature between 0.23 and 2.1 T. SD simulations showed that this feature results physically from the change in spatial quantization of the electron spin motion that occurs in the intermediate regime of field strengths where the Zeeman and zfs energies are comparable. Thus, the observed R1 dispersion for Cr(III)(acac)3 has a qualitatively different physical origin than the dispersions of Solomon–Bloembergen–Morgan theory, where R1 dispersions result from Zeeman breaking of level degeneracies. The shape of the experimental fdp suggests that the point‐dipole approximation is invalid for Cr(III)(acac)3 due to delocalization of electron spin density onto the π‐system of the acac ligand. After accounting for the altered geometry, good agreement with experiment was obtained. Copyright © 2003 John Wiley & Sons, Ltd.
Direct measurement of the transverse and longitudinal 15N chemical shift anisotropy–dipolar cross‐correlation rate constants using 1H‐coupled HSQC spectra
Authors: Hall Jennifer B. , Fushman David
Published: January 2005

We describe direct methods for the measurement of the transverse and longitudinal 15N chemical shift anisotropy–dipolar cross‐correlation rates based on comparison of the 15N doublet components observed in 1H‐coupled 1H–15N HSQC‐type spectra. This allows the determination of the cross‐correlation rates with no need for correction factors associated with other methods. The signal overlap problem of coupled HSQC spectra is addressed by using the IPAP scheme (Ottiger M, Delaglio F, Bax A. J. Magn. Reson. 1998; 131: 373). The methods proposed here use a conventional t1 evolution period, which allows one to minimize the truncation artifacts observed in a constant‐time‐type experiment (Hall JB, Dayie K, Fushman D. J. Biomol. NMR 2003; 26: 181). Applications of these measurements to the B3 domain of protein G are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Reorientational dynamics of glycerol derived from temperature‐dependent multi‐nuclear magnetic resonance relaxation data
Authors: Friedrich Anke , Dölle Andreas , Zeidler Manfred D.
Published: January 2005

Longitudinal1H,2H and13C relaxation rates of [1H8]glycerol and [2H8]glycerol have been recorded at 250.13 MHz, 38.27 MHz and 62.89 MHz respectively, over the temperature range 260 to 350 K. In addition, the nuclear Overhauser enhancement factors of13C nuclei were recorded, since they depend only on the reorientational dynamics. It proved possible to fit all experimental data to a Cole–Davidson model extended by the Vogel–Fulcher–Tammann temperature dependence and the Lipari–Szabo libration parameter. Separate parameters were obtained for the inner CH and the outer CH2groups. The overall picture of glycerol is one of a hydrogen‐bonded liquid, where the outer CH2groups perform fast librational motions whereas the inner CH group is rigidly fixed. Copyright © 2003 John Wiley & Sons, Ltd.
Methyl TROSY: explanation and experimental verification
Authors: Ollerenshaw Jason E. , Tugarinov Vitali , Kay Lewis E.
Published: January 2005

In TROSY experiments, relaxation interference effects are exploited to produce spectra with improved resolution and signal‐to‐noise. Such experiments cannot be explained using the standard product operator formalism, but must instead be analyzed at the level of individual density matrix elements. Herein we illustrate this point using an example from our recent work on a TROSY 1H–13C correlation experiment for methyl groups in large proteins. Methyl groups are useful spectroscopic probes of protein structure and dynamics because they are found throughout the critical core region of a folded protein and their resonances are intense and well dispersed. Additionally, it is relatively easy to produce highly deuterated protein samples that are 1H,13C labeled at selected methyl positions, facilitating studies of high molecular weight systems. Methyl groups are relaxed by a network of 1H–1H and 1H–13C dipolar interactions, and in the macromolecular limit the destructive interference of these interactions leads to unusually slow relaxation for certain density matrix elements. It is this slow relaxation that forms the basis for TROSY experiments. We present a detailed analysis of evolution and relaxation during HSQC and HMQC pulse schemes for the case of a 13C1H3 spin system attached to a macromolecule. We show that the HMQC sequence is already optimal with respect to the TROSY effect, offering a significant sensitivity enhancement over HSQC at any spectrometer field strength. The gain in sensitivity is established experimentally using samples of two large proteins, malate synthase G (81.4 kDa) and ClpP protease (305 kDa), both highly deuterated and selectively 1H,13C‐labeled at isoleucine δ methyl positions. Copyright © 2003 John Wiley & Sons, Ltd.
8S paramagnetic centres in molecular assemblies: possible effect of their proximity on the water proton relaxivity
Authors: Nicolle Gaëlle M. , Helm Lothar , Merbach André E.
Published: January 2005

EPR spectra of gadolinium chelates were recorded showing electron spin relaxation enhancement due to intramolecular Gd(III)–Gd(III) interaction. This enhancement was separated from other relaxation processes by replacing successively Gd(III) by the very similar Y(III). X‐band EPR line widths of the binuclear complex Gd2(OHEC)2− increase by a factor of 1.2 to 1.8 with respect to YGd(OHEC)2−. Electron spin relaxation of Gd(III) bound on the surface of micelles formed by gadofluorine 8 increases linearly with the mole fraction of Gd(III) versus Y(III). It has been shown that the increase in electron spin relaxation due to Gd–Gd interactions decreases 1H relaxivity measured on surrounding water protons. In the case of gadolinium‐based magnetic resonance imaging contrast agents this effect can limit maximum relaxivity achieved by optimizing rotational tumbling and water exchange process. Copyright © 2003 John Wiley & Sons, Ltd.
Solution‐phase chemical shift anisotropy as a promising tool to probe intermolecular interactions and peptide bond geometry: a case study on 15N‐labeled Nα‐t‐Boc‐L‐valine
Authors: Kövér Katalin E. , Batta Gyula , Hruby Victor J.
Published: January 2005

Geometry‐dependent chemical shift anisotropy (CSAg) values of 1H and 15N nuclei have been determined in solution for 15N‐labeled, Nα‐t‐Boc‐L‐valine by measurements of CSA/dipole–dipole cross‐correlated relaxation rates using longitudinal variants of the recently proposed one‐dimensional cross‐correlation experiments. We demonstrate that solvent dependence of the CSAg is an invaluable tool for monitoring intermolecular H‐bonding interactions. In addition, enhanced temperature dependence was observed for CSAg, which indicates that the anisotropy of chemical shift is more sensitive to subtle changes in the electronic environment of the nucleus than the motionally averaged isotropic chemical shift.

15N CSAg values have been determined in cyclosporin A at natural isotope abundance using the proposed 1H‐detected pulse schemes. A remarkable correlation was observed between the measured 15N CSAg and the peptide ω angle, taken from the X‐ray structure of cyclosporin A. Copyright © 2003 John Wiley & Sons, Ltd.
Simulation of radio‐frequency field inhomogeneity effects: application to pulse trains aimed at the determination of CSA–dipolar interference terms
Authors: Leclerc Sébastien , Bouguet‐Bonnet Sabine , Mutzenhardt Pierre , Brondeau Jean , Canet Daniel
Published: January 2005

The cross‐correlation relaxation rate constant between dipolar interaction and chemical shift anisotropy (interference term) is of considerable interest for structural and dynamical determinations. The present study focuses on methods related to its impact on longitudinal nuclear relaxation, and especially to a procedure based on the applications of a train of π pulses applied to both nuclei involved in such a process (Levitt MH, Di Bari L. Bull. Magn. Reson. 1994; 16: 94–114). The resulting steady state leads, in principle, to a straightforward determination of the relevant interference term. Simulations taking into account inhomogeneity of the radio‐frequency (RF) field show that artifacts are responsible for instabilities which in practice preclude such a determination. An alternative method making use of a very limited number of RF pulses, combined with an appropriate filter, proves to be rather robust in view of achieving a proper measurement of the required interference term. Copyright © 2003 John Wiley & Sons, Ltd.
Nuclear spin relaxation study of the solution reorientation of 3,5‐dichlorophenyl‐ and phenylethynyl‐mercury cyanide molecules and shielding tensors of nuclei forming the –HgCN and –CCHgCN groups: estimation of the heavy atom effect of mercury
Authors: Molchanov Sergey , Gryff‐Keller Adam
Published: January 2005

3,5‐Dichlorophenylmercury cyanide (1) and phenylethynylmercury cyanide (2) dissolved in DMSO‐d6 have been investigated using 13C, 15N and 199Hg NMR and density functional theory (DFT) calculations. The longitudinal relaxation times of 13C and 199Hg nuclei of compounds 1 and 2 and of the 15N nucleus of 1 have been measured at two magnetic fields. On the basis of these data the rotational diffusion constants describing the reorientation rates of the investigated molecules in solution and the shielding anisotropy parameters for nuclei of atoms forming the –HgCN group have been determined. The available NMR characteristics of several other cyanomercury compounds and those containing the ethynylmercury fragment have also been collected. The experimental values of carbon and nitrogen shielding parameters for the cyanomercury and ethynylmercury groups have been compared with those calculated theoretically using the DFT GIAO method. This comparison has allowed an estimation of the size of the deshielding heavy atom effect experienced by the sp‐hybridized mercury‐bonded carbons atoms. Copyright © 2003 John Wiley & Sons, Ltd.
Shuttling device for high‐resolution measurements of relaxation and related phenomena in solution at low field, using a shared commercial 500 MHz NMR instrument
Authors: Redfield Alfred G.
Published: January 2005

An apparatus is described that can pneumatically move an aqueous liquid NMR sample sealed in a 5 or 8 mm standard tube, from the center of a standard Varian 500 MHz spectrometer and probe out to any position in its fringe field, and back, under computer control. Applications to low‐field relaxation and other measurements are discussed briefly, particularly using 31P, and 15N and 13C with proton detection, utilizing the full power of the commercial system for preparation before, and detection after, a relaxation or mixing interval at low field. Transverse relaxation, polarization transfer, and other transverse manipulations are virtually impossible with this apparatus while the sample is at the low (fringe) field, because of the tremendous inhomogeneity of that field. The spectrometer and probe are unmodified commercial products and the apparatus is expected to be usable in any other system or field without much modification. The apparatus is wheeled to the instrument and installed, and later removed without trace, in less than 1 h each way, including a probe change. A pneumatic glass shuttle tube, 22 mm inside diameter, held in an aluminum support tube, is temporarily inserted in place of the upper tube that is supplied by the manufacturer to be inserted into the top of the magnet. A standard thin‐walled NMR tube is connected to a plastic piston shuttle that is moved up or down inside the shuttle tube, by low vacuum or pressure applied from the top. The low value of magnetic field, where the relaxation process measured occurs, is determined by a movable mechanical stop whose position is changed manually between runs. The downward path is initiated by a short higher pressure pulse, followed by a long lower pressure interval. The round trip time limit is about 0.2 s, suitable for relaxation rate measurements in the range up to about 10 s−1. Variable‐temperature operation uses the regulator of the host instrument. After an overview, a detailed description of all aspects of construction and use is provided. The shuttling apparatus itself is relatively straightforward, but development of a simple sample confinement method was difficult, as expected. Problems of bubble formation and of denaturation of a protein are partly solved, and sample loading and sealing is easy. Pulse programs for this apparatus are easily generated from otherwise standard pulse sequences by addition of a few simple instructions. Operation does not require any special knowledge, nor much extra training. A major result of our program is to show that the sensitivity using such a shuttle can be that of the host instrument, not affected by such possible problems as vibration, and only reduced by the predictable losses due to relaxation during the 200–300 ms round trip shuttle time, and the inability to utilize solvent flipback methods. Copyright © 2003 John Wiley & Sons, Ltd.
β‐Cyclodextrin adducts of Gd(III) chelates: useful models for investigating the structural and dynamic determinants of the relaxivity of gadolinium‐based systems
Authors: Aime Silvio , Gianolio Eliana , Terreno Enzo , Menegotto Ivan , Bracco Chiara , Milone Luciano , Cravotto Giancarlo
Published: January 2005

Gadolinium‐chelates bearing hydrophobic substituents on their surfaces form inclusion complexes with β‐cyclodextrin. When the chelate contains more than one substituent, the observed relaxation enhancement has to be analysed on the basis of the contributions arising from the actual speciation of the resulting inclusion complexes. This analysis allows the assessment of the binding constants for the individual inclusion complexes, as well as their specific relaxation enhancements. The relaxivities obtained of the supramolecular adducts display a good linearity with their molecular weights to outline that, in these systems, the main determinant of the relaxation enhancement is represented by the overall molecular reorientational time. Copyright © 2003 John Wiley & Sons, Ltd.
Reorientational dynamics of two isomers of thiacalix[4]arene
Authors: Lang Jan , Tošner Zdeněk , Lhoták Pavel , Kowalewski Jozef
Published: January 2005

Molecular reorientation and local mobility of two isomers of 25,26,27,28‐tetrapropoxy‐2,8,14,20‐tetrathiacalix[4]arene, cone and 1,3‐alternate, were studied by means of NMR relaxation. The chemical shift anisotropy of 13C nuclei was determined in the solid state. Nuclear relaxation due to dipole–dipole interaction and chemical shift anisotropy was analysed in the framework of the Lipari–Szabo approach. The aromatic core of both isomers was found rigid on the subnanosecond time scale. The amplitude of the local motion of the lower rim propoxy substituents increases towards the methyl ends. The methylene groups of the propoxy residues of the cone isomer possess more motional freedom than in the 1,3‐alternate, where they are sterically hindered by the adjacent aromatic rings. Global reorientation of the cone is slower than the motion of the 1,3‐alternate, which rotates partly anisotropically. Copyright © 2003 John Wiley & Sons, Ltd.