bluuebunny/crossref_metadata_2025 huggingface dataset:
Identifying risk for recurrent hepatocellular carcinoma after liver transplantation: Implications for surveillance studies and new adjuvant therapies
Authors: Chan Edie Y. , Larson Anne M. , Fix Oren K. , Yeh Matthew M. , Levy Adam E. , Bakthavatsalam Ramasamy , Halldorson Jeffrey B. , Reyes Jorge D. , Perkins James D.
Published: June 2008

The recurrence of hepatocellular carcinoma (HCC) is a major cause of mortality for patients transplanted with HCC. There currently exists no standard method for identifying those patients with a high risk for recurrence. Identification of factors leading to recurrence is necessary to develop an efficient surveillance protocol and address new potential adjuvant therapies. We conducted a retrospective review of 834 consecutive liver transplants from 1/1/1996 to 12/31/2005 (mean follow-up 1303 ± 1069 days) at one institution and 352 consecutive transplants from 1/2/2002 to 12/31/2005 (mean follow-up 836 ± 402 days) at a second institution. The test cohort comprised patients identified with HCC in their explanted livers from 1/1/2001 to 12/31/2005 at the first institution. Explant pathology and donor and recipient characteristics were reviewed to determine factors associated with HCC recurrence. These predictors were validated in the remaining liver transplant recipients. The test cohort had 116 patients with findings of HCC in their explanted livers. Twelve patients developed recurrent HCC. Stepwise logistic regression identified 4 independent significant explant factors predictive of recurrence. Size of one tumor (>4.5 cm), macroinvasion, and bilobar tumor were positive predictors of recurrence, whereas the presence of only well-differentiated HCC was a negative predictor. Designating each significant factor with points in relation to its odds ratio, a Predicting Cancer Recurrence Score (PCRS) with results ranging from −3 to 6 was developed that accurately determined risk of recurrence. These findings were then applied to the two validation cohorts, which confirmed the high predictive value of this model. In conclusion, patients transplanted for HCC with a PCRS of ≤0 have a low risk of recurrence. Patients with a PCRS of 1 or 2 have a moderate risk of recurrence, and those with a PCRS of ≥3 have a high risk for recurrence. Liver Transpl 14:956–965, 2008. © 2008 AASLD.
Graft size, donor age, and patient status are the indicators of early graft function after living donor liver transplantation
Authors: Yoshizumi Tomoharu , Taketomi Akinobu , Uchiyama Hideaki , Harada Noboru , Kayashima Hiroto , Yamashita Yo-Ichi , Soejima Yuji , Shimada Mitsuo , Maehara Yoshihiko
Published: June 2008

No reliable model for predicting early graft function and patient survival after living donor liver transplantation (LDLT) exists. The aim of this study was to establish a new formula for predicting early graft function and prognosis using technetium-99m galactosyl-human serum albumin (Tc-GSA) liver scintigraphy. The ratio of the hepatic uptake ratio of Tc-GSA to the clearance index of Tc-GSA (LHL/HH) was determined 7 days after LDLT. There were 22 patients with a ratio greater than 1.3 and 6 patients with a ratio less than 1.3. Graft function on the 14th postoperative day (POD) was compared between the 2 groups. A new formula to predict the LHL/HH score was established as follows: LHL/HH (predictive score) = 0.011 × graft weight (%) − 0.016 × donor age − 0.008 × Model for End-Stage Liver Disease score − 0.15 × shunt (if present) + 1.757 (r
2 = 0.497, P < 0.01). This predicted LHL/HH ratio was compared to the graft function on POD 14 for 110 LDLT patients. The total bilirubin (TB) and prothrombin time international normalized ratio (PT-INR) in the group with an LHL/HH score ≥ 1.3 were lower than those in the group with an LHL/HH score < 1.3. The TB, PT-INR, and volume of ascites in the group with a predictive score ≥ 1.3 (n = 86) were lower than those in the group with a score < 1.3 (n = 24). The 6-month survival probability was improved in the group with a predictive score ≥ 1.3. In conclusion, this preoperative calculated LHL/HH score is correlated with graft function and short-term prognosis. Thus, this predictive model may allow transplant surgeons to use a living donor left lobe graft with greater confidence. Liver Transpl 14:1007–1013, 2008. © 2008 AASLD.
Should we still offer split-liver transplantation for two adult recipients? A retrospective study of our experience
Authors: Giacomoni Alessandro , Lauterio Andrea , Donadon Matteo , De Gasperi Andrea , Belli Luca , Slim Abdallah , Dorobantu Bogdan , Mangoni Iacopo , De Carlis Luciano
Published: June 2008

The role of split-liver transplantation (SLT) for two adult recipients is still a matter of debate, and no agreement exists on indications, surgical techniques, and results. The aim of this study was to retrospectively analyze the outcome of our series of SLT. From May 1999 to December 2006, 16 patients underwent SLT at our unit. We used 9 full right grafts (segments 5–8) and 7 full left grafts (segments 1–4). The splitting procedure was always carried out in situ with a fully perfused liver. Postoperative complications were recorded in 8 (50%) patients: 5 (55%) in full right grafts and 3 (43%) in full left grafts. No one was retransplanted. After a median follow-up of 55.82 months (range, 0.4–91.2), 5 (31%) patients died, and the 1-, 3-, and 5-year overall survival rate for patients and grafts was 69%. We considered as a control group for the global outcome 232 whole liver transplantations performed at our unit in the same period of time. Postoperative complications were recorded in 53 (23%) patients, and after a median follow-up of 57.37 months (mean, 55.11; range, 1–102.83), the 1-, 3-, and 5-year overall patient survival was 87%, 82%, and 80%, respectively. In conclusion, SLT for two adult recipients is a technically demanding procedure that requires complex logistics and surgical teams experienced in both liver resection and transplantation. Although the reported rate of survival might be adequate for such a procedure, more efforts have to be made to improve the short-term outcome, which is inadequate in our opinion. The true feasibility of SLT for two adults has to be considered as still under investigation. Liver Transpl 14:999–1006, 2008. © 2008 AASLD.
Ischemic preconditioning and intermittent clamping confer protection against ischemic injury in the cirrhotic mouse liver
Authors: Jang Jae Hwi , Kang Koo-Jeong , Kang Yuna , Lee In-Seon , Graf Rolf , Clavien Pierre-Alain
Published: June 2008

Surgery on cirrhotic livers is fraught with complications, and many surgeons refrain from operating on patients with cirrhosis. Surgical procedures include temporal occlusion of blood flow resulting in ischemia. The mechanisms of protective strategies to prevent ischemic injury in patients with cirrhosis are not fully understood. The aim of this study was to evaluate how the cirrhotic liver tolerates an ischemic insult, whether mechanisms other than those observed in the normal liver are active, and whether intermittent clamping and preconditioning, which are known as safe surgical strategies in normal and steatotic livers, confer protection to the cirrhotic liver. We applied partial hepatic inflow occlusion to cirrhotic mice fed carbon tetrachloride according to different vascular occlusion protocols: intermittent clamping with 15 or 30 minute cycles of ischemia or ischemic preconditioning prior to 60 or 75 minutes of ischemia. Continuous ischemia (60 or 75 minutes) served as controls. The results showed that the cirrhotic liver was significantly more susceptible to 60 minutes of ischemia than the normal liver. Apoptosis was higher in the normal liver, whereas necrosis was a predominant feature in the cirrhotic liver. Both protocols of intermittent vascular occlusion and ischemic preconditioning dramatically prevented injury compared to continuous occlusion for 60 minutes. This protection was associated with reduced necrosis and apoptosis, and particularly reduced activation of the apoptotic pathway through mitochondria. In conclusion, this study extends the protective effects of ischemic preconditioning and intermittent clamping to the cirrhotic liver, highlighting a diminished apoptotic pathway with dramatic improvement in the development of necrosis. Liver Transpl 14:980–988, 2008. © 2008 AASLD.
Hepatopulmonary syndrome: Use of extracorporeal life support for life-threatening hypoxia following liver transplantation
Authors: Fleming Geoffrey M. , Cornell Timothy T. , Welling Theodore H. , Magee John C. , Annich Gail M.
Published: June 2008

Hepatopulmonary syndrome is an uncommon complication of nonacute liver failure, and in rare cases, hypoxia may be the presenting sign of liver dysfunction. The condition, once thought to be a contraindication, is improved in most cases by transplantation. There is a significant risk of postoperative, hypoxia-related morbidity and mortality in patients with hepatopulmonary syndrome. We present a case of life-threatening hypoxia following liver transplantation for liver failure and associated hepatopulmonary syndrome, with successful management using extracorporeal membrane oxygenation. Liver Transpl 14:966–970, 2008. © 2008 AASLD.
Comparison of the USCOM ultrasound cardiac output monitor with pulmonary artery catheter thermodilution in patients undergoing liver transplantation
Authors: Wong Lai-Sze Grace , Yong Boon-Hun , Young Karl Kang , Lau Lee-Sung , Cheng King-Lik , Man Jeff Siu-Fan , Irwin Michael G.
Published: June 2008

The aim of the study was to compare the standard technique of cardiac output determination by pulmonary artery catheter thermodilution (PAC-TD) with a noninvasive ultrasound Doppler monitor (USCOM Pty., Ltd., Coffs Harbour, Australia) in surgery for liver transplantation. We wished to determine if the degree of accuracy would allow the ultrasound cardiac output monitor (USCOM) to be used as an alternative monitor in a clinical setting in which wide fluctuations in cardiac output could be expected. This was a prospective method comparison study, with 71 paired measurements obtained in 12 patients undergoing liver transplantation in a university teaching hospital. Bland-Altman analysis of the 2 techniques showed a bias of 0.39 L/minute, with the USCOM cardiac output lower compared with that of PAC-TD. The bias was small and did not vary with the magnitude of the cardiac output. The 95% limits of agreement were −1.47 and 2.25 L/minute. There was good repeatability for USCOM measurements, with a repeatability coefficient of 0.43 for USCOM versus 0.77 for PAC-TD. We conclude that USCOM is acceptable for the clinical determination of noninvasive cardiac output, particularly in situations in which tracking changes over time is more important than knowing the precise value. However, the utility of USCOM is limited by its inability to measure pulmonary artery pressure. Liver Transpl 14:1038–1043, 2008. © 2008 AASLD.
Dichloroacetate stabilizes the intraoperative acid-base balance during liver transplantation
Authors: Shangraw Robert E. , Lohan-Mannion Deirdre , Hayes Agnes , Moriarty Rose M. , Fu Rongwei , Robinson Stephen T.
Published: June 2008

Lactic acidosis occurs during orthotopic liver transplantation (OLT), especially during the anhepatic and early postreperfusion phases. Dichloroacetate (DCA) inhibits pyruvate dehydrogenase kinase-1, indirectly activating mitochondrial pyruvate dehydrogenase. This, in turn, markedly reduces systemic lactate production and, to a lesser extent, increases hepatic lactate uptake. The result is moderation of lactic acidosis in many clinical conditions. This study evaluated the efficacy of DCA in controlling lactic acidosis during OLT and improving perioperative outcome from OLT. After informed consent, 250 patients for OLT received either intraoperative DCA or placebo. DCA (40 mg/kg intravenously) or placebo was administered after anesthesia induction and repeated 4 hours later. Intraoperative measures were arterial blood gases, lactate, and Na+ and utilization of blood products, CaCl2, and NaHCO3. Outcome measures were time to tracheal extubation, intensive care unit length of stay, hospital length of stay, requirement for postoperative plasma transfusion, retransplantation, and perioperative mortality. DCA reduced the arterial lactic acid concentration by an average of 44% (1.8 mmol L−1, P < 0.001), stabilized the acid-base balance, and reduced NaHCO3 administration by 80% (P < 0.001). Postoperatively, DCA-treated patients required 50% less postoperative plasma transfusion (2 versus 4 units, respectively, P = 0.016), but the incidence of transfusion was similar in both groups (62% versus 60%, P = 0.381). DCA did not alter time to extubation, intensive care unit length of stay, or hospital length of stay. In conclusion, DCA attenuated lactic acidosis during OLT, stabilizing the intraoperative acid-base balance and decreasing NaHCO3 use. DCA decreased postoperative plasma transfusion requirement but otherwise had no measurable effect on perioperative outcome parameters. Liver Transpl 14:989–998, 2008. © 2008 AASLD.
Platelets in liver transplantation: Friend or foe?
Authors: Pereboom Ilona T. A. , Lisman Ton , Porte Robert J.
Published: June 2008

Apart from the well-known role of blood platelets in hemostasis, there is emerging evidence that platelets have various nonhemostatic properties that play a critical role in inflammation, angiogenesis, tissue repair and regeneration, and ischemia/reperfusion (I/R) injury. All these processes may be involved in the (patho)physiological alterations occurring in patients undergoing liver transplantation. Experimental and clinical research points toward a dualistic role of platelets in patients undergoing liver transplantation, resulting in both beneficial and detrimental effects. Although a low platelet count is generally considered a risk factor for perioperative bleeding, recent studies have indicated that platelet function in patients with cirrhosis may not be as abnormal as previously assumed. Platelet transfusions are frequently considered in liver transplant recipients to correct low platelet counts and to prevent bleeding; however, evidence-based transfusion thresholds are lacking, and the other detrimental and nonhemostatic properties of platelets are generally not weighed in this respect. First, platelets have been shown to contribute to I/R injury of the liver graft via induction of sinusoidal endothelial cell apoptosis. Second, platelet transfusion has been identified as an independent risk factor for reduced survival via mechanisms that are not completely understood yet. On the other hand, recent studies indicate that platelets are critically involved in restoration after liver injury and in liver regeneration via serotonin-mediated mechanisms. These findings make platelets both friend and foe in liver transplantation. The scientific challenge will be to further dissect the mechanisms and clinical relevance of these contrasting roles of platelets in liver transplantation. Liver Transpl 14:923–931, 2008. © 2008 AASLD.
Overcoming the limitations of living donor and split liver transplantation: A proposal for adult recipients (the best of the east in the west)
Authors: Heaton Nigel , Srinivasan Parthi , Prachalias Andreas , Rela Mohamed
Published: June 2008

A shortage of organs for liver transplantation has encouraged the development of advanced surgical strategies to increase the donor pool. We present a technical strategy that combines the established techniques of split liver transplantation and left lateral segment donation from living donors for adult recipients. This strategy could provide an additional source of organs for liver transplantation. Liver Transpl 14:932–934, 2008. © 2008 AASLD.
The prevalence of Parkinson's disease in rural Tanzania
Authors: Dotchin Catherine , Msuya Olivia , Kissima John , Massawe John , Mhina Ali , Moshy Addess , Aris Eric , Jusabani Ahmed , Whiting David , Masuki Gabriel , Walker Richard
Published: June 2008

The prevalence of Parkinson's disease (PD) varies worldwide from 7 to 450 per 100,000, and appears low in sub‐Saharan Africa (SSA) but few data exist. We conducted a prevalence study of PD in rural Tanzania. A door‐to‐door study was conducted in the Hai district project area (population 161,071), using a screening questionnaire followed by structured history and examination of positive responders. Diagnosis was based on the UK PD Society Brain Bank Criteria. 33 (23 men) cases of PD were detected, with mean age 74 years (range 38–94). One patient died before the prevalence date. 78% were previously undiagnosed and untreated. Mean duration of symptoms was 5 years, and median Hoehn and Yahr stage 3. Crude prevalence rates were 30/100,000 (men), 11/100,000 (women) and 20/100,000 (combined). The direct age‐standardized prevalence rates compared with the UK population were 64/100,000 (men), 20/100,000 (women) and 40/100,000 (combined). These rates are higher than previously reported from SSA, but still lower than the developed world. Many PD patients in SSA may never be diagnosed or treated, with consequent reduction in their life expectancy and quality of life. With the world population ageing PD is predicted to become an increasing problem. © 2007 Movement Disorder Society
The current clinical management of Huntington's disease
Authors: Phillips Wendy , Shannon Kathleen M. , Barker Roger A.
Published: June 2008

Huntington's disease is a neurodegenerative condition, characterized by movement disorders, cognitive decline, and psychiatric disturbance. We review the pharmacological management of the various movement disorders associated with the disease, the cognitive decline and the commonly encountered behavioral disturbances. We discuss the nonclassical features of the disease, important in the management of these patients. Nonpharmacological support including genetic counseling and therapy and the importance of palliative care are also addressed. Finally, experimental approaches that may soon impact upon clinical practice are discussed. © 2008 Movement Disorder Society
A novel mutation of the ε‐sarcoglycan gene in a Chinese family with myoclonus‐dystonia syndrome
Authors: Chen Xue‐Ping , Zhang Yang‐Wei , Zhang Shu‐Shan , Chen Qin , Burgunder Jean‐Marc , Wu Shu‐Hui , Yang Yuan , Luo Zu‐Ming , Shang Hui‐Fang
Published: June 2008

In a Chinese myoclonus‐dystonia syndrome (MDS) family presented with a phenotype including a typical MDS, cervical dystonia, and writer's cramp, genetic analyses revealed a novel 662 + 1insG heterozygous mutation in exon 5 in the ε‐sarcoglycan (SGCE) gene, leading to a frameshift with a down stream stop codon. Low SGCE mRNA levels were detected in the mutation carriers by real‐time PCR, suggesting that the nonsense mutation might interference with the stability of SGCE mRNA. This is the first report on Chinese with a SGCE mutation leading to MDS. Our data support the fact that same mutation of SGCE gene can lead to a varied phenotype, even in the same family. © 2008 Movement Disorder Society
Measurement of T1 and T2 in the cervical spinal cord at 3 tesla
Authors: Smith Seth A. , Edden Richard A.E. , Farrell Jonathan A.D. , Barker Peter B. , Van Zijl Peter C.M.
Published: June 2008

T1 and T2 were measured for white matter (WM) and gray matter (GM) in the human cervical spinal cord at 3T. T1 values were calculated using an inversion‐recovery (IR) and B1‐corrected double flip angle gradient echo (GRE) and show significant differences (p = 0.002) between WM (IR = 876 ± 27 ms, GRE = 838 ± 54 ms) and GM (IR = 973 ± 33 ms, GRE = 994 ± 54 ms). IR showed significant difference between lateral and dorsal column WM (863 ± 23 ms and 899 ± 18 ms, respectively, p = 0.01) but GRE did not (p = 0.40). There was no significant difference (p = 0.31) in T2 between WM (73 ± 6 ms) and GM (76 ± 3 ms) or between lateral and dorsal columns (lateral: 73 ± 6 ms, dorsal: 72 ± 7 ms, p = 0.59). WM relaxation times were similar to brain structures with very dense fiber packing (e.g., corpus callosum), while GM values resembled deep GM in brain. Optimized sequence parameters for maximal contrast between WM and GM, and between WM and cerebrospinal fluid (CSF) were derived. Since the spinal cord has rostral‐caudal symmetry, we expect these findings to be applicable to the whole cord. Magn Reson Med 60:213–219, 2008. © 2008 Wiley‐Liss, Inc.
Spatiotemporal magnetic field monitoring for MR
Authors: Barmet Christoph , Zanche Nicola De , Pruessmann Klaas P.
Published: June 2008

MR experiments frequently rely on signal encoding by the application of magnetic fields that vary in both space and time. The accurate interpretation of the resulting signals often requires knowledge of the exact spatiotemporal field evolution during the experiment. To better fulfill this need, a new approach is presented that enables measuring the field evolution concurrently with any MR sequence. Miniature NMR probes are used to monitor the MR phase evolution around the object under investigation. Based on these data, a global phase model is calculated that can then be used as a basis for processing the actual image or spectroscopic data. The new method is demonstrated by MRI of a phantom, using spin‐warp, spiral, and EPI trajectories. Throughout, the monitoring results enabled highly accurate image reconstruction, even in the presence of massive gradient imperfections. Magn Reson Med 60:187–197, 2008. © 2008 Wiley‐Liss, Inc.
Evaluation of an AIF correction algorithm for dynamic susceptibility contrast‐enhanced perfusion MRI
Authors: Brunecker Peter , Endres Matthias , Nolte Christian H. , Schultze Jörg , Wegener Susanne , Jungehülsing Gerhard Jan , Müller Bianca , Kerskens Christian M. , Fiebach Jochen B. , Villringer Arno , Steinbrink Jens
Published: June 2008

For longitudinal studies in patients suffering from cerebrovascular diseases the poor reproducibility of perfusion measurements via dynamic susceptibility‐weighted contrast‐enhanced MRI (DSC‐MRI) is a relevant concern. We evaluate a novel algorithm capable of overcoming limitations in DSC‐MRI caused by partial volume and saturation issues in the arterial input function (AIF) by a blood flow stimulation‐study. In 21 subjects, perfusion parameters before and after administration of blood flow stimulating L‐arginine were calculated utilizing a block‐circulant singular value decomposition (cSVD). A total of two different raters and three different rater conditions were employed to select AIFs: Besides 1) an AIF selection by an experienced rater, a beginner rater applied a steady state‐oriented strategy, returning; 2) raw; and 3) corrected AIFs. Highly significant changes in regional cerebral blood flow (rCBF) by 9.0% (P < 0.01) could only be found when the AIF correction was performed. To further test for improved reproducibility, in a subgroup of seven subjects the baseline measurement was repeated 6 weeks after the first examination. In this group as well, using the correction algorithm decreased the SD of the difference between the two baseline measurements by 42%. Magn Reson Med 60:102–110, 2008. © 2008 Wiley‐Liss, Inc.
Estimating intracellular lithium in brain in vivo by localized 7Li magnetic resonance spectroscopy
Authors: Komoroski Richard A. , Pearce John M.
Published: June 2008

The therapeutic mechanism of action of lithium (Li) in bipolar disorder is unknown. While Li is presumed to work intracellularly in the brain, the fraction of intracellular Li in the brain in vivo is not known. It has not yet been possible to determine, directly and noninvasively, the intra‐ to extracellular distribution of Li in human brain in vivo. Lithium‐7 (7Li) MR is the only technique available for measuring noninvasively the concentration of Li in the brain in vivo. Here the individual components of biexponential 7Li transverse (T2) relaxation in rat brain in vivo are identified with intra‐ and extracellular Li, and used to estimate its compartmental distribution. Intracellular T2 was 14.6 ± 6.9 ms, while extracellular T2 was 160 ± 52 ms in nine rats. The fraction of intracellular brain Li ranged from 37% to 75% (mean: 63 ± 11%). Further, the biexponential T2 results provided the basis for estimating Li compartmental distribution from monoexponential T2 decays using a simple linear approximation. The fraction of intracellular Li estimated from monoexponential T2 decays agreed with the corresponding biexponential estimates in most cases. Magn Reson Med 60:21–26, 2008. © 2008 Wiley‐Liss, Inc.
Moment and direction of the spoiler gradient for effective artifact suppression in RF‐spoiled gradient echo imaging
Authors: Leupold Jochen , Hennig Jürgen , Scheffler Klaus
Published: June 2008

Radiofrequency (RF) ‐spoiled gradient echo sequences were developed with the aim to produce images with T1weighted contrast within short acquisition time. Over the past two decades, this type of sequence has proven to be a robust technique and represents a reliable workhorse in clinical MRI. This study presents an analysis of ghost artifacts, which appear occasionally in RF‐spoiled gradient echo images. It is demonstrated that the artifacts result from intrinsically emerging signal oscillations, which can be damped down by the application of spoiler gradients. Magn Reson Med 60:119–127, 2008. © 2008 Wiley‐Liss, Inc.
Circumferential strain in the wall of the common carotid artery: Comparing displacement‐encoded and cine MRI in volunteers
Authors: Lin Alexander P. , Bennett Eric , Wisk Lauren E. , Gharib Morteza , Fraser Scott E. , Wen Han
Published: June 2008

The walls of conduit arteries undergo cyclic stretching from the periodic fluctuation of arterial pressure. Atherosclerotic lesions have been shown to localize to regions of excessive stretching of the arterial wall. We employed a displacement encoding with stimulated echoes (DENSE) sequence to image the motion of the common carotid artery wall and map the two‐dimensional (2D) circumferential strain. The sequence utilizes a fully‐balanced steady‐state free‐precession (SSFP) readout with 0.60 mm in‐plane resolution. Preliminary results in volunteers at 1.5T (N = 4) and 3.0T (N = 17) are compared to measurements of the lumen circumference from cine images. The agreement between the two independent measurements at both field strengths (P ≤ 0.001) supports the use of DENSE as a means to map the pulsatile strain in the carotid artery wall. Magn Reson Med 60:8–13, 2008. © 2008 Wiley‐Liss, Inc.
Contrast‐enhanced magnetic resonance angiography in peripheral arterial disease: Improving image quality by automated image registration
Authors: Menke Jan
Published: June 2008

In peripheral arterial disease, contrast‐enhanced MR angiography (MRA) is a noninvasive imaging alternative for catheter‐based digital subtraction angiography (DSA). In DSA, final images are generated by subtracting a native mask image from subsequent contrast‐enhanced images. Image quality is routinely improved by digitally shifting the mask image prior to subtraction if the patient has moved during angiography. This study investigated whether such image registration may also help to improve the image quality of MRA. In all, 545 MRA examinations of pelvic and leg arteries in patients with symptoms of peripheral arterial disease were studied retrospectively. Standard nonregistered MRA was compared to automatically linear, affine, and warp registered MRA by visual analysis and by three image quality parameters, including vessel detection probability (VDP) of angiographic maximum intensity projections. Most MRA of pelvic and upper leg arteries showed good nonregistered image quality. However, the 15% of lower legs with a body shift of 1 mm or more had relatively low nonregistered image quality, which improved significantly with image registration (VDP gain more than 18%, P < 0.05). The visual analysis gave similar results. In conclusion, image registration can improve image quality of MRA in peripheral arterial disease, especially in the lower legs. Magn Reson Med 60:224–229, 2008. © 2008 Wiley‐Liss, Inc.
Visualizing water clearance in the lung with MRI
Authors: Vidarsson Logi , Helm Emma , O'Brodovich Hugh , Macgowan Christopher K.
Published: June 2008

Current indirect measurements of alveolar fluid clearance (AFC) suggest that the rate of fluid clearance correlates with morbidity and mortality in patients with pulmonary edema. In a traditional AFC‐measurement, fluid laced with a tracer macromolecule is instilled into the lung and thereafter repeated samples of the instilled fluid are extracted from the lung's fluid‐filled airspaces. The change in concentration of the tracer molecule indicates the AFC‐rate. In this work, a new MRI technique was developed to image lung water clearance by adding Gadolinium‐DTPA to the instilled fluid. As fluid is absorbed by the animal, the concentration of gadolinium will increase, reducing the T1 relaxation time. By repeatedly measuring the T1 relaxation time, the AFC can be tracked over time with high spatial resolution. The new technique was tested both in phantoms and 10 Yorkshire piglets. Magn Reson Med 60:230–235, 2008. © 2008 Wiley‐Liss, Inc.
Assessing transneuronal dysfunction utilizing manganese‐enhanced MRI (MEMRI)
Authors: Serrano Faridis , Deshazer Mitchell , Smith Karen D.B. , Ananta Jeyarama S. , Wilson Lon J. , Pautler Robia G.
Published: June 2008

In this study we utilized manganese‐enhanced MRI (MEMRI) to evaluate the in vivo transneuronal efficiency of manganese ion (Mn2+) movement as a means to assess overall changes in neuronal function. We designated this extension the manganese transfer index (MTI) value. To evaluate the MTI value as an index of transneuronal physiology we examined both pharmacological agents and different mouse models of neuronal dysfunction. We found that treatment with isoflurane, which attenuates synaptic vesicle release, or memantine, which attenuates postsynaptic uptake of Ca2+ as well as Mn2+, resulted in a decrease in the MTI value. Furthermore, we evaluated if changes in the MTI value can be detected in three knockout mice with altered brain function accompanied either with or without neurodegeneration. Our data demonstrate that the MTI values either decreased or increased in response to different functional as well as anatomical changes. These results demonstrate the potential utility of the MTI value as an in vivo index for the detection of changes in neuronal function in animal models of human disease. Magn Reson Med 60:169–175, 2008. © 2008 Wiley‐Liss, Inc.
Flavonoid glucuronides with anti‐leukaemic activity from Polygonum amphibium L.
Authors: Smolarz H. D. , Budzianowski J. , Bogucka‐Kocka A. , Kocki J. , Mendyk E.
Published: June 2008

Introduction – The chemical and pharmaceutical studies carried out on species from Polygonum L. genus showed biological activity both of the extracts and the components isolated from them. These results were the impulse to examine Polygonum amphibium L.

Objective – The aim of this study was the isolation of active components from methanol extract and the determination of their cytotoxic effect on human leukaemic cell lines.

Methodology – Three flavonoid components from butanol soluble fractions of methanol extract by CC and PC preparative chromatography were isolated. Their structures were established on the basis of 1H, 13C and correlation (DEPT, H‐H, COSY, HMQC, HMBC) NMR, UV and FAB‐MS spectroscopic techniques. The evaluation of the anti‐leukaemic activities of 1 and 2 against Jurkat and HL60 cell lines was carried out in vitro using annexin V fluorescence assay.

Results – Two new flavonoid glucuronides, quercetin‐3‐O‐β‐glucuronide (1) and quercetin‐3‐O‐α‐rhamnosyl‐(1 → 2)‐β‐glucuronide (2), and kaempferol‐3‐O‐α‐rhamnosyl‐(1 → 2)‐β‐glucuronide (3), were isolated from Polygonum amphibium L. It was demonstrated that the glucuronides of quercetin are able to induce apoptosis in the tested human leukaemic cells. These compounds penetrate through cytoplasm to the cellular nucleus of the cultured cells, and give intensive apoptotic responses in the stimulated leukaemic cells. The number of apoptotic cells increased with the concentration (1 nm to 10 µm) of 1 or 2 and periods of exposure (1–3 days).

Conclusion – Compounds 1 and 2 may be considered good candidates for leukaemia chemotherapeutic agents. Copyright © 2008 John Wiley & Sons, Ltd.
Thermomechanical analysis and modeling of the extrusion coating process
Authors: Sollogoub C. , Felder E. , Demay Y. , Agassant J.F. , Deparis P. , Mikler N.
Published: June 2008

During the extrusion coating process, a polymer film is extruded through a flat die, stretched in air, and then coated on a substrate (steel sheet in our case) in a laminator consisting of a chill roll and a flexible pressure roll. The nip, i.e. the area formed by the contact between the pressure and the chill rolls, constitutes the heart of the extrusion coating process. Indeed, in this region, some of the most critical properties, such as adhesion, barrier properties, optical properties, are achieved or lost. In this article, we first present an experimental investigation of the coating step, which enables to characterize the leading thermomechanical phenomena. It is shown that there is no polymer macroscopic flow in the nip, but a local flow within the asperities of the steel substrate surface. This microscopic flow, at the interface between the film and the substrate, is slowed by strong cooling conditions in the nip. Several models are then proposed, giving access to the temperature profile through polymer thickness and substrate, the pressure distribution in the nip as well as the behavior of the polymer melt in the nip at the interface with the substrate. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Valorization of poly(butylene terephthalate) wastes by blending with virgin polypropylene: Effect of the composition and the compatibilization
Authors: Barhoumi Najoua , Jaziri Mohamed , Massardier Valérie , Cassagnau Philippe
Published: June 2008

Blends of recycled poly(butylene terephthalate) (PBT) parts obtained from scrapped cars, and virgin polypropylene (PP), were prepared in a twin‐screw extruder at different compositions. Selected compositions were also prepared with the presence of ethylene‐co‐glycidyl methacrylate copolymer (E‐GMA) and ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E‐MA‐GMA) compatibilizers. The effect of the composition and the type of compatibilizer, as well as the mixing conditions, on the morphology phase, thermal, viscoelastic behavior, and mechanical properties of the blends has been investigated. Blends PP/PBT of various composition exhibit a coarse morphology and a poor adherence between both phases, resulting in the decrease of ductility, whereas at weak deformation, PBT reinforced the tensile properties of PP. Addition of E‐GMA and E‐MA‐GMA to the PP/PBT blend exhibited a significant change in morphology and improved ductility because of interfacial reactions between PBT end chains and epoxy groups of GMA that generate EG‐g‐PBT copolymer. Moreover, thermal and viscoelastic study indicated that the miscibility of PP and PBT has been improved further and the reactions were identified. The E‐MA‐GMA results in the best improvement of ductility. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Photooxidative behavior of polystyrene–montmorillonite nanocomposites
Authors: Oliveira C.F.P. , Carastan D.J. , Demarquette N.R. , Fechine G.J.M.
Published: June 2008

The weathering behavior of polystyrene and polystyrene–montmorillonite composites containing 2.5, 5.0, and 7.5 wt% of montmorillonite (MMT) was investigated. Samples were exposed to UV radiation for periods of up to ∼12 weeks and their molecular weight, chemical changes, and mechanical properties were monitored as a function of time. The addition of MMT was shown to improve the photostability of all composites investigated, probably because of a screen effect against UV radiation and barrier effect against diffusion of oxygen promoted by the silicate layers of MMT. Scanning electron microscopy of fracture surfaces of degraded samples showed that there is a degraded layer near the surface that provided a recovery of tensile strength of the samples. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Effects of initiator type in rigid polyurethane foams
Authors: Kim Sung Hee , Lim Ho , Kim Byung Kyu
Published: June 2008

Rigid polyurethane foams (RPUFs) have been synthesized from high‐functional polymeric 4,4′‐diphenylmethane diisocyanate (PMDI) and polypropylene glycols (PPG), which were prepared from sorbitol and its combinations with toluene diamine (TDA, T), ethylene diamine (EDA, E), and sucrose/glycerin (G) using environmentally friendly blowing agent, i.e., HFC 365mfc and/or distilled water. Effects of initiator type and blowing agent content have been analyzed in terms of cell morphology, thermal conductivity, and mechanical and dynamic mechanical properties. It was found that TDA‐based initiators gave smallest cell, highest value of rubbery plateau modulus, and greatest thermal insulation, whereas EDA gave the greatest dimensional stability. It was also found that the foam properties were largely governed by the blowing agent, whereas initiator gave fine controls of the properties. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Detecting crystallization structure evolution of polypropylene injection‐molded bar induced by nucleating agent
Authors: Bai Hongwei , Wang Yong , Song Bo , Li Yanli , Liu Li
Published: June 2008

The crystallization structures of Polypropylene (PP) injection‐molded bars nucleated by nucleating agent were detected from the skin layer to the core zone, layer by layer. α‐phase nucleating agent 1,3:2,4‐bis (3,4‐dimethylbenzylidene) sorbitol (DMDBS, Millad 3988), β‐phase nucleating agent aryl amides compounds (TMB‐5), and their compounds were introduced into PP matrix, respectively. The relative content of β‐phase PP in the different zones of an injection‐molded bar was characterized and calculated by Wide angle X‐ray diffraction (WAXD) and Differential scanning calorimetry (DSC). The results show that, whether in pure PP or in nucleated PP, both β‐phase PP and α‐phase PP grow in the skin layer of the injection‐molded bar. However, in the intermediate layers and the core zone, the crystallization structures of PP are dependent on the used nucleating agent. β‐phase is the main crystallization structure of TMB‐5 (0.1 and 0.2 wt%) nucleated PP, and α‐phase in DMDBS (0.1 and 0.2 wt%) nucleated PP. Compounding nucleating agents with 0.1 wt% DMDBS and 0.1 wt% TMB‐5 induces PP crystallization almost in β‐phase; however, PP nucleated by 0.2 wt% DMDBS and 0.2 wt% TMB‐5 crystallizes exclusively in α‐phase. The crystallization mechanism of PP nucleated by compounding nucleating agents was further studied in this work. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. II. Results and discussion
Authors: Yang Sang Sik , Kwon Tai Hun
Published: June 2008

In the accompanying paper, Part I, presented are the physical modeling and numerical formulation of new lateral motion modelings. In Part II, new models developed in Part I are validated by the successful comparison of calculated residual stress profile with the literature data. The predicted results of the birefringence, residual stress distribution, and shrinkage from new lateral motion modeling are in better agreement with corresponding experimental data than those from the conventional ones. The new model prediction falls between those of two extreme cases corresponding to conventional models. As a result of extensive parametric study of processing conditions, the developed analysis system is found to be capable of successfully predicting the tendency of shrinkage behavior varying with most of processing conditions. In this regard, the new model enables better analysis based design and optimization of precision injection‐molded products. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Unusual thermal degradation of maleic anhydride grafted polyethylene
Authors: Huang Jiann‐Wen , Lu Wei‐Chieh , Yeh Mou‐Yu , Lin Chih‐Hsiang , Tsai I‐Shou
Published: June 2008

Thermal degradation of maleic anhydride grafted polyethylene (manPE) in nitrogen and in air was studied by thermogravimetry and differential scanning calorimetry. The decomposition temperature of manPE in nitrogen shifted to a higher value with increasing heating rate, but a complex thermal phenomenon was observed when manPE decomposed in air. Chain scission and crosslinking are proposed as two counteractive factors to determine the decomposition temperature in air. Radical species (R•) and hydroxyl groups (ROH) form when manPE degraded in air. The radical species accelerate the oxidative degradation, but ROH could react with the maleic anhydride groups to form a stable crosslinking structure. Both slow heating and prolong heating at 220°C allow the stabilizing reaction to proceed to a higher degree between ROH and the maleic anhydride groups and lead to enhanced thermal stability of manPE. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. I. Development of lateral motion modeling
Authors: Yang Sang Sik , Kwon Tai Hun
Published: June 2008

The present study aims at improving the state of art physical modeling in the numerical simulation for a precision injection molding to take into account the shrinkage behavior observed by experimental measurements. In Part I, new lateral motion models have been developed to predict the birefringence, residual stress profiles, and effects of various processing conditions on the shrinkage altogether. In conventional models, the lateral motion is either allowed too early or totally prohibited in the cooling stage. With the new modeling, more general description of lateral motion has been achieved either by allowing the lateral motion if an averaged lateral residual stress reaches a certain value or by letting the lateral motion develop continuously when a shearing strength is equal to an estimated shear stress. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Luminance of injection‐molded V‐groove light guide plates
Authors: Lin T.H. , Isayev A.I. , Mehranpour M.
Published: June 2008

Injection‐molded V‐groove light‐guide plates (LGPs) were made of two optical grade polycarbonates of different viscosities at various molding conditions. Their luminance as a function of viewing angle was measured. The depth of melt filling of the grooves in LGPs was measured at different locations selected based on the melt front propagation during the cavity filling. The depth of melt filling of grooves was mostly completed during the cavity‐filling stage. It was only slightly affected by the packing pressure and packing time and strongly affected by other molding conditions and layout of the V‐grooves. Luminance of LGPs showed a strong correlation with the depth of melt filling of the V‐grooves. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
New aramid‐based nanocomposites: Synthesis and characterization
Authors: Zulfiqar Sonia , Lieberwirth Ingo , Ahmad Zahoor , Sarwar Muhammad Ilyas
Published: June 2008

New type of nanocomposites containing various proportions of montmorillonite in aromatic polyamide was prepared via solution intercalation method. Aramid chains were synthesized by reacting 4,4′‐oxydianiline with isophthaloyl chloride in N,N′‐dimethyl acetamide. Dodecylamine was used as swelling agent to change the hydrophilic nature of montmorillonite into organophilic. Appropriate amounts of organoclay were mixed in the polymer solution using high‐speed mixer for complete dispersion of the clay. Thin films cast from these materials after evaporating the solvent were characterized by XRD, TEM, mechanical, thermal, and water absorption measurements. The structure and morphology of the nanocomposites determined by XRD and TEM revealed the formation of exfoliated and intercalated clay platelets in the aramid matrix. Mechanical data indicated improvement in the tensile strength and modulus of the nanocomposites with clay loading up to 6 wt%. The glass transition temperature increased up to 12 wt% clay content and thermal stability amplified with increasing clay loading. The water absorption reduced gradually as a function of organoclay and approached to zero with 20 wt% organoclay in the aramid. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Electronic structure evidence for all‐trans poly(methylvinylidene cyanide)
Authors: Xiao Jie , Poulsen Matt , Reddy D. Sahadeva , Takacs J.M. , Losovyj Y.B. , Dowben P.A.
Published: June 2008

On the basis of a comparison of theoretical quantum calculations, by both semiempirical and ab initio methods, with photoemission and inverse photoemission results, we suggest that polymethylvinylidenecyanide (PMVC) adopts an all‐trans conformation with few, if any, alternating trans‐gauche carbon–carbon bond arrangements. The comparison of theory with the available photoemission and inverse photoemission excludes the presence of a significant fraction of gauche bonds in the polymer chains, indicative of the all‐trans conformation, with dipoles all aligned. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Temperature‐dependent deformation and damage behaviour of ultrafine‐grained copper under uniaxial compression
Authors: Yu Zhao‐Yuan , Jiang Qing‐Wei , Li Xiao‐Wu
Published: June 2008

The plastic deformation and damage behaviour of ultrafine‐grained (UFG) copper produced by equal channel angular pressing were investigated at temperatures ranging from room temperature to 573 K under uniaxial compression. It was found that the testing temperature has a strong effect on the corresponding mechanical behaviour of UFG copper. For example, the compressive yield stress and steady flow stress of UFG copper decease generally with increasing temperature. In the case of temperatures below recrystallization, an enhanced early‐stage strain softening was observed with increasing temperature. Compressive deformation damage features of UFG copper are also strongly dependent on the temperature. Small‐ and large‐scale cracks were observed to form along the shear bands at room temperature, whereas microvoids or cracks were found to nucleate at grain boundaries at temperatures above recrystallization. At in‐between temperatures, some microvoids with various sizes were detected along the shear direction. Such temperature‐dependent deformation and damage behavior are closely related with the corresponding microstructural changes after compressive deformation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Directed Aerosol Writing of Ordered Silica Nanostructures on Arbitrary Surfaces with Self‐Assembling Inks
Authors: Pang Jiebin , Stuecker John N. , Jiang Yingbing , Bhakta Ajay J. , Branson Eric D. , Li Peng , Cesarano Joseph , Sutton David , Calvert Paul , Brinker C. Jeffrey
Published: June 2008

This paper reports the fabrication of micro‐ and macropatterns of ordered mesostructured silica on arbitrary flat and curved surfaces using a facile robot‐directed aerosol printing process. Starting with a homogenous solution of soluble silica, ethanol, water, and surfactant as a self‐assembling ink, a columnated stream of aerosol droplets is directed to the substrate surface. For deposition at room temperature droplet coalescence on the substrates and attendant solvent evaporation result in continuous, highly ordered mesophases. The pattern profiles are varied by changing any number of printing parameters such as material deposition rate, printing speed, and aerosol‐head temperature. Increasing the aerosol temperature results in a decrease of the mesostructure ordering, since faster solvent evaporation and enhanced silica condensation at higher temperatures kinetically impede the molecular assembly process. This facile technique provides powerful control of the printed materials at both the nanoscale and microscale through chemical self‐assembly and robotic engineering, respectively.