bluuebunny/crossref_metadata_2025 huggingface dataset:
An ectobiont‐bearing foraminiferan, Bolivina pacifica, that inhabits microxic pore waters: cell‐biological and paleoceanographic insights
Authors: Bernhard Joan M. , Goldstein Susan T. , Bowser Samuel S.
Published: October 2009

The presence of tests (shells) in foraminifera could be taken as an indicator that this protist taxon is unlikely to possess ectosymbionts. Here, however, we describe an association between Bolivina pacifica, a foraminiferan with a calcareous test, and a rod‐shaped microbe (bacterium or archaeon) that is directly associated with the pores of the foraminiferan's test. In addition to these putative ectosymbionts, B. pacifica has previously undescribed cytoplasmic plasma membrane invaginations (PMIs). These adaptations (i.e. PMIs, ectobionts), along with the clustering of mitochondria under the pores and at the cell periphery, suggest active exchange between the host and ectobiont. The B. pacifica specimens examined were collected from sediments overlain by oxygen‐depleted bottom waters (0.7 μM) of the Santa Barbara Basin (California, USA). An ultrastructural comparison between B. pacifica from the Santa Barbara Basin and a congener (Bolivina cf. B. lanceolata) collected from well‐oxygenated sediments (Florida Keys) suggests that PMIs, ectobionts and peripherally distributed mitochondria are all factors that promote inhabitation of microxic environments by B. pacifica. The calcitic δ13C signatures of B. pacifica and of a co‐occurring congener (B. argentea) that lacks ectobionts differ by > 1.5‰, raising the possibility that the presence of ectobionts can affect incorporation of paleoceanographic proxies.
ENTREPRENEURSHIP AND THE SPATIAL CONTEXT: EVIDENCE ON THE LOCATION OF FIRM BIRTHS IN GREECE
Authors: Daskalopoulou Irene , Liargovas Panagiotis
Published: October 2009

This paper analyses the effect of the spatial context upon entrepreneurship in Greek regions. Cross‐sectional data referring to 4151 births at NUTS III level (prefecture) are used for firm births in four industries, namely manufacturing, commerce, services, and tourism. The formulated hypotheses are in regard to the effect of agglomeration economies, defined here as urbanization and localization economies, and other factors that typically affect the location of start‐ups. Results indicate that strong localization economies exist (both of the Marshallian and the Jacobian type) while, in addition, the spatial context of entrepreneurship affects different industries in different ways.
TRADE POLICY AND CITY PRIMACY IN DEVELOPING COUNTRIES
Authors: Gelan Ayele
Published: October 2009

This paper examines the relationship between trade policy and city primacy in developing countries. A general equilibrium model was constructed and center‐periphery relations are analyzed, accounting for tensions between agglomerative and distributive forces. By applying the theoretical model through numerical simulations, we analyzed how trade policy affects the interactions between these forces. We distinguished between import tariffs and export trade barriers. The results suggested that trade liberalization can reduce the dominance of mega‐cities in developing countries, but only when improvements are made to internal and external factors inhibiting their export trade. These include improving domestic transport infrastructure and reducing barriers to exports from developing countries by developed nations.
How Do Students Learn Theology?
Authors: Saines Don
Published: October 2009

This paper explores the way students learn theology through a small qualitative research project. It is undertaken in conversation with current higher education learning theory. This learning theory suggests that it is important to discover how a student conceptualizes learning and how they perceive the teaching environment. Students interviewed increasingly spoke of the value of this academic or more cognitive side of learning as they learned “deep approaches.” Important in this movement to deep, transformational learning was the presence of a relational teaching environment in which peers and teachers played a crucial role. This present study offers support to the view that the tradition of the learning community remains important for deploying deep approaches to the learning of theology in higher education. The paper argues that these relational principals of teaching and learning remain important in the face of the increased use of technology‐based tools and other pedagogical challenges to theological education today.
Variable selection method for quantitative trait analysis based on parallel genetic algorithm
Authors: Mukhopadhyay Siuli , George Varghese , Xu Hongyan
Published: October 2009

Selection of important genetic and environmental factors is of strong interest in quantitative trait analyses. In this study, we use parallel genetic algorithm (PGA) to identify genetic and environmental factors in genetic association studies of complex human diseases. Our method can take account of both multiple markers across the genome and environmental factors, and also can be used to do fine mapping based on the results of haplotype analysis to select the markers that are associated with the quantitative traits. Using both simulated and real examples, we show that PGA is able to choose the variables correctly and is also an easy‐to‐use variable selection tool.
Influence of smoking abstinence and nicotine replacement therapy on heart rate and QT time‐series
Authors: Lewis M. J. , Balaji G. , Dixon H. , Syed Y. , Lewis K. E.
Published: October 2009

Many smokers attempt to quit without using nicotine replacement therapy (NRT) or pharmacotherapy, i.e. ‘cold‐turkey’. The cardiac implications of this are important but are incompletely understood. Previous studies have associated smoking cessation with improvements in heart rate (HR) and its variability, but its influence on QT time‐series is unclear. Furthermore, the relative influence on these parameters of acute nicotine withdrawal and of NRT has not been adequately compared. Additional insight might come from analysing the dynamic (e.g. fractal) properties of electrocardiographic data during different levels of nicotine exposure. We examined the influence of smoking cessation, during cold‐turkey and subsequent NRT, on HR and QT time‐series during 30 days of smoking abstinence. Seven smokers and sixteen healthy non‐smokers received ECG monitoring at baseline (Day 0). Smokers subsequently refrained from smoking without using NRT for 24 h, and then received NRT for 29 days. ECG monitoring was repeated at Days 1, 7, 30. Following smoking cessation we observed that: HR and rate‐corrected QT were both reduced, heart rate variability (HRV) increased (improved), and QT variability index (QTVI) showed signs of improvement (trend only). Improvements in HR and QT were maintained throughout NRT use, whilst improvements in HRV and QTVI were sustained for at least the early stages of NRT. The dynamic (multifractal) properties of HR and QT were similar for smokers and non‐smokers, and were unchanged by smoking abstinence or NRT. Our results provide tentative evidence that electrocardiographic improvements during a cold‐turkey smoking quit attempt (acute nicotine withdrawal) are maintained during NRT pharmacotherapy.
ASDIN: Patency Rates for Angioplasty in the Treatment of Pacemaker‐Induced Central Venous Stenosis in Hemodialysis Patients: Results of a Multi‐Center Study
Authors: Asif Arif , Salman Loay , Carrillo Roger G. , Garisto Juan D. , Lopera Gustavo , Barakat Urwa , Lenz Oliver , Yevzlin Alexander , Agarwal Anil , Gadalean Florin , Sachdeva Bharat , Vachharajani Tushar J. , Wu Steven , Maya Ivan D. , Abreo Ken
Published: October 2009

While hemodialysis access ligation has been used to manage pacemaker (PM) and implantable cardioverter‐defibrillator (ICD) lead‐induced central venous stenosis (CVS), percutaneous transluminal balloon angioplasty (PTA) has also been employed to manage this complication. The advantages of PTA include minimal invasiveness and preservation of arteriovenous access for hemodialysis therapy. In this multi‐center study we report the patency rates for PTA to manage lead‐induced CVS. Consecutive PM/ICD chronic hemodialysis patients with an arteriovenous access referred for signs and symptoms of CVS due to lead‐induced CVS were included in this analysis. PTA was performed using the standard technique. Technical and clinical success was examined. Technical success was defined as the ability to successfully perform the procedure. Clinical success was defined as the ability to achieve amelioration of the signs and symptoms of CVS. Both primary and secondary patency rates were also analyzed. Twenty‐eight consecutive patients underwent PTA procedure. Technical success was 95%. Postprocedure clinical success was achieved in 100% of the cases where the procedure was successful. The primary patency rates were 18% and 9% at 6 and 12 months, respectively. The secondary patency rates were 95%, 86%, and 73% at 6, 12, and 24 months, respectively. On average, 2.1 procedures/year were required to maintain secondary patency. There were no procedure‐related complications. This study finds PTA to be a viable option in the management of PM/ICD lead‐induced CVS. Additional studies with appropriate design and sample size are required to conclusively establish the role of PTA in the management of this problem.
Salvage of Accidentally Sectioned Peritoneal Catheter: Report of Three Cases
Authors: Hooper Casandra Puig , Rivera Maite , Marcén Roberto , Martins Judith , Teruel Jose Luis , De La Morena Carmina , Ortuno Joaquin
Published: October 2009

Peritoneal dialysis (PD) accounts for 6% of patients on maintenance dialysis. There are several factors responsible for this low prevalence. Transfer of patients to hemodialysis when any problem in the technique is present is probably one of the most frequent reasons. Thus, when a problem in the PD catheter appears they are routinely removed instead of subjecting to salvage procedures. We report three cases of accidental cutting of the peritoneal catheter and present the steps taken to salvage the catheter without discontinuing the technique and avoiding withdrawal of the catheter.
Reverse‐Loop Upper Arm Arteriovenous Graft for Chronic Hemodialysis
Authors: Yang Wen‐Shin , Chen Tzu‐Chun , Chen Jer‐Shen , Chan Chih‐Yang
Published: October 2009

Options for an upper arm arteriovenous graft (AVG) commonly include the placement of a straight prosthetic graft connecting the brachial artery to the axillary vein. However, such configuration leads to underutilization of the upper arm veins, resulting in the loss of venous capital in the upper arm for future secondary fistula creation. In this retrospective analysis, we evaluated seven patients who had upper‐arm AVGs created in a reverse‐loop configuration. The prosthetic graft was created by connecting the brachial artery close to the cubital fossa and tunneled subcutaneously in a looped fashion distally thereby connecting the basilic or deep brachial vein just above the elbow. Endpoints were interventions, thrombosis, and loss of access at the last examination. The brachial vein was used in two patients and the basilic vein in the other five. The median duration of follow‐up with 100% patency of the AVGs was 10.0 (range, 3.0–25.0) months. Patients were able to achieve a target hemodialysis dose with a (Kurea × td)/Vurea value of 1.4 (range, 1.2–1.5). The median flow rates achieved were 205.0 (range, 203.3–236.7) and 266.7 (range, 203.3–276.7) ml/minute at the first and 3‐month dialysis sessions, respectively. The median dialysis venous pressures were 128.0 (range, 108.3–178.0) and 131.0 (range, 116.7–148.7) mmHg at the first and third month after operation, respectively. The median peak systolic velocity ratios of artery–graft and vein–graft junctions were 2.1 (range, 1.4–2.4) and 3.0 (range, 2.3–3.8) cm/second, respectively. In conclusion, this is a logical approach for patients who have exhausted their forearm vessels for AVG creation. In addition, it also provides a platform for future creation of a secondary fistula in the upper arm.
Carotid Stent‐Supported Angioplasty via Radiobrachial Route
Authors: Janjua Nazli , Verma Navin , Alkawi Ammar , Kirmani Jawad F. , Qureshi Adnan I.
Published: October 2009

Endovascular stent‐supported angioplasty is a treatment option for atherosclerotic disease of the cervical internal carotid artery in high‐risk patients. The traditional transfemoral approach is not suitable for patients who suffer from common femoral artery or abdominal aorta atheropathy. We report a case of carotid stent deployment using the radial route in a 68‐year‐old man with type B aortic dissection, having severe right internal carotid artery origin stenosis, presenting with ipsilateral retinal ischemic events. Technical aspects of carotid stenting via the radial approach are described and the related literature is discussed.
Diffusion Tensor Imaging and Fiber‐Tracking in Marchiafava‐Bignami Disease
Authors: Sair Haris I. , Mohamed Feroze B. , Patel Sunil , Kanamalla Uday S. , Hershey Beverly , Hakma Zakaria , Faro Scott H.
Published: October 2009

Marchiafava‐Bignami disease, a rare disorder most commonly seen in patients with a history of alcohol consumption, involves demyelination and subsequent necrosis of the corpus callosum. Diffusion tensor imaging demonstrates regional abnormalities in the corpus callosum that are not evident by conventional magnetic resonance imaging (MRI). Furthermore, fiber‐tracking demonstrates significant disruption of axonal fiber bundles within the corpus callosum, most marked within the body, corresponding to the clinical finding of interhemispheric disconnection, which is characteristic of the disease.
Three‐Dimensional Anisotropy Contrast Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction (3DAC PROPELLER) on a 3.0T System: A New Modality for Routine Clinical Neuroimaging
Authors: Nakada Tsutomu , Matsuzawa Hitoshi , Fujii Yukihiko , Takahashi Hitoshi , Nishizawa Masatoyo , Kwee Ingrid L.
Published: October 2009

Background. Clinical magnetic resonance imaging (MRI) has recently entered the “high‐field” era, and systems equipped with 3.0–4.0T superconductive magnets are becoming the gold standard for diagnostic imaging. While higher signal‐to‐noise ratio (S/N) is a definite advantage of higher field systems, higher susceptibility effect remains to be a significant trade‐off. To take advantage of a higher field system in performing routine clinical images of higher anatomical resolution, we implemented a vector contrast image technique to 3.0T imaging, three‐dimensional anisotropy contrast (3DAC), with a PROPELLER (Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction) sequence, a method capable of effectively eliminating undesired artifacts on rapid diffusion imaging sequences. Methods. One hundred subjects (20 normal volunteers and 80 volunteers with various central nervous system diseases) participated in the study. Anisotropic diffusion‐weighted PROPELLER images were obtained on a General Electric (Waukesha, WI, USA) Signa 3.0T for each axis, with b‐value of 1100 sec/mm2. Subsequently, 3DAC images were constructed using in‐house software written on MATLAB (MathWorks, Natick, MA, USA). Results. The vector contrast allows for providing exquisite anatomical detail illustrated by clear identification of all major tracts through the entire brain. 3DAC images provide better anatomical resolution for brainstem glioma than higher‐resolution T2 reversed images. Degenerative processes of disease‐specific tracts were clearly identified as illustrated in cases of multiple system atrophy and Joseph–Machado disease. Conclusion. Anatomical images of significantly higher resolution than the best current standard, T2 reversed images, were successfully obtained. As a technique readily applicable under routine clinical setting, 3DAC PROPELLER on a 3.0T system will be a powerful addition to diagnostic imaging.
Dynamics of Dot‐Like Hemosiderin Spots on T2*‐Weighted MRIs Associated with Stroke Recurrence
Authors: Imaizumi Toshio , Honma Toshimi , Horita Yoshifumi , Chiba Masahiko , Kawamura Maiko , Miyata Kei , Kohama Ikuhide , Niwa Jun
Published: October 2009

Background and Purpose. Dot‐like low‐intensity spots (dot‐like hemosiderin spots: dotHSs) on gradient echo T2*‐weighted (‐w) brain magnetic resonance imaging (MRIs) are frequently associated with cerebral small vessel disease (SVD), including deep intracerebral hemorrhages and lacunar infarctions. This study investigated how numbers of newly appeared dotHSs contribute to recurrent SVD. Methods. We prospectively analyzed numbers of newly appeared dotHSs in 12 patients with prior SVD (8 males, 4 females; mean 67.6 ± 10.7 years old) readmitted with recurring SVD between October 2001 and March 2003. Numbers of appeared dotHSs per year were counted on T2*‐w MRI scans after SVD recurrence and compared to previous MRIs. Seventy‐one outpatients (35 males, 36 females; mean 64.3 ± 9.6 years old) with histories of intracerebral hemorrhages (ICH) that came to the hospital during the study period served as controls. The hazard ratio (HR) for recurrence was estimated from a multivariate logistic regression model, using the number of appeared dotHSs (per year) and other risk factors. Results. Multivariate analyses revealed that an elevated rate of recurrence was found in patients with substantial numbers of appeared dotHSs (≥5/year) (HR, 7.34; P= 0.0008). We also analyzed factors associated with the numbers of appeared dotHSs. A number of appeared dotHSs (≥5/year) was significantly and independently associated with the initial number of dotHSs (≥10) on T2*‐w MRIs following the first SVD (HR, 18.6; P= 0.0001). Conclusions. Though a small sample size limited the power of our analyses, our findings suggest that a number of newly appeared dotHSs may be associated with SVD recurrence.
Colloid Cyst: Diffusion MR Imaging Findings
Authors: Sener R. Nuri
Published: October 2009

Colloid cysts usually have viscid gelatinous material or denser content. In an adult patient with a colloid cyst, diffusion magnetic resonance (MR) imaging was applied to detect its features with this sequence that if its viscous content may lead to a hyperintense appearance (decreased diffusion pattern) on b= 1000 sec/mm2 images similar to epidermoids. The colloid cyst had hypointense signal on the b= 1000 sec/mm2 image. The ADC map had more information that the ADC value of the cyst was 1.58 × 10−3 mm2/sec. This value was apparently higher than that of normal cerebral parenchyma, and was apparently lower than that of CSF. These diffusion MR imaging features of the colloid cyst are consistent with an elevated diffusion pattern in contrast to epidermoids.
Differentiating Intracranial Aspergillosis from a High Grade Glioma Using MRI and MR Spectroscopic Imaging
Authors: Pollack Erica , Bhaya Anil , Law Meng
Published: October 2009

We compare the MRI (magnetic resonance imaging) and MRSI (MR spectroscopic imaging) findings in a patient with intracerebral aspergillosis to those typically seen in an infiltrating high‐grade glioma (HGG). We demonstrate paramagnetic areas of T2‐hypointensity due to the pathologic deposition of iron and other paramagnetic elements seen in intracerebral aspergillosis. We also demonstrate the diffusion‐weighted imaging (DWI) findings and discuss how MR spectroscopy can be useful in differentiating an aspergilloma from a high‐grade glioma.
A Progressive Neurologic Disorder with Multiple CNS Lesions: A Neuroimaging Clinicopathologic Correlation
Authors: Chowdhary Sajeel , Chamberlain Marc
Published: October 2009

A 51‐year‐old man with a diagnosis of myelodysplasia and non‐Hodgkin's lymphoma underwent an unmatched allogenic bone marrow transplantation and was treated posttransplant with chronic immunosuppressive medication. Eight months following transplantation, he presented with progressive dysarthria, cognitive and visual decline. Evaluation included brain magnetic resonance (MR) imaging demonstrating multifocal areas of increased T2 and FLAIR (fluid attenuated inversion recovery) signals involving the left frontal, parietal, and occipital lobes. The MR lesions demonstrated diffuse increased signal on DWI (diffusion‐weighted images) and normal to low signal on ADC (apparent diffusion coefficients). Contrast‐enhanced T1 images were unremarkable. Lumbar puncture revealed a mild elevation in cerebrospinal fluid (CSF) protein. CSF PCR assay for viral DNA fragments were negative on two occasions. Serum serology for HIV was negative as well. A brain biopsy was subsequently performed. The clinical and neuroimaging differential diagnoses as well as neuropathologic correlation are presented.
Decompression Sickness: MRI of the Spinal Cord
Authors: Kei Pin Lin , Choong Chew Thye , Young Timothy , Lee Sze Haur , Lim C. C. Tchoyoson
Published: October 2009

Decompression sickness (DCS) typically causes changes in the white matter of the spinal cord on MR imaging. We present a case of DCS in a scuba diver with dorsal white matter lesions typical of venous infarction. In addition, some central gray matter involvement was noted. Characteristic features of venous spinal cord infarction can be recognized on MR imaging in DCS but may be more extensive in severe cases.
An Uncommon Variant of Fibromuscular Dysplasia
Authors: Spengos Konstantinos , Vassilopoulou Sofia , Tsivgoulis Georgios , Papadopoulou Marianna , Vassilopoulos Demetris
Published: October 2009

Fibromuscular dysplasia is a rare cause of stroke affecting mostly young females. It is characterized by the typical “string of beads” sign located mostly bilaterally in the midcervical portion of the carotid or vertebral arteries. We present the uncommon case of borderzone hemispheric infarction in a man with isolated unilateral fibromuscular dysplasia affecting continuously the distal extracranial and proximal intracranial portion of the left internal carotid artery leading to distal hypoperfusion and ischemia.
Conventional MRI in Multiple Sclerosis
Authors: Filippi Massimo , Rocca Maria A.
Published: October 2009

During the past 10 years, conventional magnetic resonance imaging (cMRI) has become an established tool for the assessment of patients with multiple sclerosis (MS) and to monitor treatment trials. This is mainly due to the sensitivity and reproducibility of cMRI in the detection of MS‐related damage. A large effort has also been devoted to develop imaging strategies capable of providing accurate estimates of the extent of disease‐related damage not only in the brain, but also in the spinal cord and optic nerve. Guidelines have been defined to integrate MR findings in the diagnostic evaluation of patients at presentation with clinically isolated syndromes suggestive of MS, and specific acquisition protocols have been offered for monitoring longitudinal changes in patients with established disease. Despite the fact that the role of cMRI in MS has been profoundly obviated by the advent of modern and quantitative MR techniques, several issues are still unresolved. Technical development in acquisition and postprocessing, as well as the introduction of high‐field magnets in the clinical arena, are likely to increase our understanding of disease pathobiology, mainly through an increased ability to quantify the extent of gray matter damage.
Extensive Brainstem Ischemia on Neuroimaging Does Not Preclude Meaningful Recovery from Locked‐In Syndrome: Two Cases of Endovascularly Managed Basilar Thrombosis
Authors: Tomycz Nestor D. , Holm Margo B. , Horowitz Michael B. , Wechsler Lawrence R. , Raina Ketki , Gupta Rishi , Jovin Tudor G.
Published: October 2009

We report 2 patients with angiographically demonstrated basilar artery thrombosis who received emergent intra‐arterial thrombolysis with successful recanalization of the basilar artery. In the ensuing weeks after the procedure, both patients were in a locked‐in state and had sustained large bilateral regions of pontine ischemia on brain imaging. Following aggressive supportive care and rehabilitation, outcomes obtained prospectively revealed that both patients made a remarkable recovery, becoming fully independent with Barthel scores of 20 and modified Rankin scores of 2.
Changes in Serum Calcium Levels Associated with Catheter‐Based Cerebral Angiography
Authors: Hassan Ameer E. , Hussain Muhammad S. , Chowdhury Farys , Khan Asad , Harris‐Lane Pansy , Qureshi Adnan I.
Published: October 2009

BACKGROUND AND OBJECTIVE

Digital subtraction angiography is performed with agents such as iodinated contrast and intravenous heparin, which can alter electrolyte levels. If severe enough, these alterations may produce symptoms in patients in the post‐procedural period. We performed this study to evaluate serum calcium level changes after cerebral angiography.

MATERIALS AND METHODS

The preangiographic and postangiographic serum calcium levels of 87 patients were reviewed and analyzed. Patients were grouped based on when the postangiographic serum calcium level was drawn in relation to the angiographic procedure (0‐6 hours, 6‐12 hours, 12‐18 hours, and 18‐24 hours).

RESULTS

A significant reduction in serum calcium was observed in the 0‐ to 6‐hours, 6‐ to 12‐hours, and 12‐ to 18‐hours groups (P < .05). The differences between the preangiographic and postangiographic serum calcium levels were 0.91 mg/dL, 0.59 mg/dL, and 0.55 mg/dL in the 0‐ to 6‐hours, 6‐ to 12‐hours, and 12‐ to 18‐hours groups, respectively. The difference in the 18‐ to 24‐hours group (0.27 mg/dL) was not statistically significant. None of the patients was clinically symptomatic from this decrease in serum calcium levels.

CONCLUSION

An asymptomatic but significant decrease in serum calcium levels is seen following cerebral angiography. Possible mechanisms include chelation from the contrast agent or intravenous heparin. The reduction in serum calcium is transient, appearing to resolve within 24 hours.
Neuroimaging Findings in Hyperargininemia
Authors: Güngör Serdal , Akıncı Ayşehan , Fırat Ahmet Kemal , Tabel Yılmaz , Alkan Alpay
Published: October 2009

In hyperarginenemia, there is a defect in argininase enzyme, which is a catalyzer of urea cycle. Though the pathogenesis of neuronal damage in hyperargininemia is not clear, high serum and cerebrospinal fluid arginine levels can be directly related with neuronal damage. In this study, our aim was to assess brain magnetic resonance images and magnetic resonance spectroscopy (MRS) patterns of two siblings with hyperarginenemia. We acquired single voxel MRS from the white matter to show the myelination pattern and to figure out any abnormal peak of metabolite stored due to enzymatic defect. We observed mild cerebral and cerebellar atrophy and infarct at bilateral posterior putamen and insular cortex localization on conventional images and elevated choline/creatine ratios and abnormal peak at 3.8 ppm, most likely representing arginine deposition. To the best of our knowledge, this is the first article revealing the brain MRS pattern of hyperargininemia. We reported the clinical and imaging findings of patients and discuss the correlation.
Systemic Thrombolysis Based on CT or MRI Stroke Imaging
Authors: Veronel Dimitro , Ringelstein Adrian , Cohnen Matthias , Yong Mei , Siebler Mario , Seitz Rüdiger J.
Published: October 2009

BACKGROUND

Computed tomography (CT) and magnetic resonance imaging (MRI) are tools of investigation in acute stroke. We wondered if the additional information offered by MRI outweighs the disadvantage of its longer scanning duration for systemic thrombolysis.

METHODS

Two hundred ninety‐four consecutive patients (66 ± 13 years) were subjected to thrombolyis between 1999 and 2004. Inclusion criteria were ischemic infarction, scoring at entry and discharge with the NIH stroke scale and modified Rankin scale, systemic thrombolysis within 3 hours after symptom onset, multimodal MRI or standard CT. Subgroup analysis of 42 patients compared standard CT with CT and CT angiography.

RESULTS

Patients were similarly affected on admission (P > .1). At discharge, 6 days after stroke onset, the patients investigated with MRI were less impaired than those investigated with standard CT (P < .05). Symptomatic hemorrhage was rare in both groups. Also, patients investigated with CT and CT angiography were less impaired at discharge than those with standard CT (P < .02). A multifactorial regression showed that systolic blood pressure, glucose level and initial neurological impairment determined the neurological outcome at discharge.

CONCLUSIONS

Systolic blood pressure, glucose level and neurological impairment but not the imaging modality determined the neurological outcome following systemic thrombolysis in the 3‐hour window.
Studies on the Value of Diffusion‐Weighted MR Imaging in the Early Prediction of Periventricular Leukomalacia
Authors: Fu Jianhua , Xue Xindong , Chen Liying , Fan Guoguang , Pan Li , Mao Jian
Published: October 2009

OBJECTIVE

Periventricular leukomalacia (PVL) is the most common cerebral injury in premature infants. While cranial ultrasonography and conventional magnetic resonance imaging (MRI) offer little for its early diagnosis, still they are much favored at present. Based on the pathologic mechanism of ischemic cerebral injury in PVL, we attempt to elucidate the effects of diffusion‐weighted MR imaging (DWI) for the early diagnosis of PVL.

METHODS

Twelve cases of PVL in premature infants confirmed by MRI examinations were included in the current study. All cases underwent DWI in addition to conventional MR imaging (T1‐weighted [T1W] and T2‐weighted [T2W]) 7 days, 2 weeks, and 4∼8 weeks after birth, respectively.

RESULTS

Initial DWI examination (carried out at an average of 4.5 days after birth) revealed symmetrical and diffuse high signal in bilateral periventricular areas in all cases, while conventional MRI demonstrated normal signal. DWI examination of 2 weeks later showed irregular inhomogeneous signals in cerebral white matter, while conventional MRI revealed hyperintensity on T1WI and slight hypointensity on T2WI in corresponding areas. Four weeks later, DWI revealed various intensities of cystic low signals beside lateral ventricles, while conventional MRI showed hypointensity on T1WI and hyperintensity on T2WI in corresponding lesion, ie, change in cystic PVL. Four months later, conventional MRI evidenced gradual shrink and disappearance of cystic cavity, reduction in cerebral white matter, and ventricle enlargement.

CONCLUSIONS

Symmetrical, diffuse hyperintensity in both lateral periventricular white matter on DWI was the earliest sign of PVL in premature infants. Imaging abnormalities provided by DWI had a close correlation with the results obtained by conventional MRI performed at the advanced stage of PVL, which suggests that DWI may be an important sequence for the early evaluation of cerebral white matter injury as well as for the prediction of PVL occurrence in premature infants.
Impact of Reperfusion after 3 Hours of Symptom Onset on Tissue Fate in Acute Cerebral Ischemia
Authors: Bang Oh Young , Liebeskind David S. , Buck Brian H. , Yoon Sa Rah , Alger Jeffry R. , Ovbiagele Bruce , Saver Jeffrey L. ,   for the UCLA MRI Investigators
Published: October 2009

BACKGROUND

Reperfusion of penumbral tissue is a promising strategy for treatment of acute cerebral ischemia more than 3 hours from symptom onset. However, there has been only sparse direct evidence that reperfusion after 3 hours prevents infarct growth.

METHODS

We analyzed clinical and serial magnetic resonance imaging (MRI) data on patients who received endovascular recanalization therapy 3‐12 hours after last known well time. Multimodal MRIs were acquired pretreatment, early (1‐20 hours), and late (2‐7 days) after treatment. Degree of recanalization was assessed on end of procedure catheter angiogram, degree of reperfusion on early posttreatment perfusion MRI, and infarct growth by analysis of diffusion lesion volumes on pretreatment and late MRIs.

RESULTS

Twenty‐seven (12 men, 15 women) underwent endovascular recanalization procedures at 6.0 ± 2.1 hours (range, 3.0‐11.5 hours) after last known well time. Immediate posttreatment perfusion lesion (Tmax ≥4 seconds) volume correlated strongly with infarct growth (r= .951, P < .001), exceeding the correlations of vessel recanalization score (r=−.198, P= .446) and pretreatment diffusion‐perfusion mismatch volume (r= .518, P= .033). Without reperfusion, enlargement of DWI lesion volume was observed in all patients, and extent of enlargement depended on volume of immediate posttreatment perfusion defects.

CONCLUSION

Our data indicate that posttreatment reperfusion is the major determinant of threatened tissue outcome, and suggest reperfusion even after 3 hours of symptom onset can alter tissue fate over a wide range of mismatch volumes.
Rheolytic Thrombectomy for Dural Venous Sinus Thrombosis
Authors: Modi Kalgi , Misra Vijay , Reddy Pratap
Published: October 2009

BACKGROUND AND PURPOSE

Cerebral venous thrombosis is a rare condition. Its diagnosis and management can be difficult. Treatment options include systemically delivered anticoagulation or thrombolysis. Intrasinus thrombolysis is an increasingly used intervention but it increases the risk of hemorrhage, especially in patients who have a rapidly deteriorating neurological condition. Mechanical thrombectomy that provides rapid canalization without increased risk of hemorrhage is an attractive alternative treatment.

METHODS

We describe the use of AngioJet rheolytic thrombectomy in 4 patients with extensive cerebral venous sinus thrombosis, preexisting intracranial hemorrhage, and severe progressive neurological deficit despite heparin therapy.

RESULTS

Partial or complete sinus patency was restored in all 4 patients and complete neurological recovery was achieved in 3 patients.

CONCLUSION

Intracranial hemorrhage or a rapidly deteriorating neurological condition may preclude the use of thrombolytic agents in the treatment of patients with cerebral venous sinus thrombosis. In such patients, mechanical thrombectomy offers a useful alternative.
Premorbid Use of Statins Is Associated with Higher Recanalization Rates in Patients with Acute Ischemic Stroke Undergoing Endovascular Treatment
Authors: Georgiadis Alexandros L. , Hussein Haitham M. , Vazquez Gabriela , Shah Qaisar , Suri M. Fareed K. , Ezzeddine Mustapha A. , Qureshi Adnan I.
Published: October 2009

BACKGROUND AND PURPOSE

Statins have been shown to have lipid‐independent (pleiotropic) effects that may be beneficial in the management of vascular disease. We evaluated the effect of premorbid statin use on recanalization in patients with acute ischemic stroke undergoing endovascular treatment.

METHODS

We retrospectively reviewed the charts of all patients who had undergone endovascular treatment for acute ischemic stroke at our institution. Computed tomography scans obtained after treatment were assessed for the presence of hemorrhagic transformation by an independent reviewer. The primary endpoint was partial or complete recanalization (at least 1 grade improvement in the Qureshi scale). Secondary endpoints were hemorrhagic transformation and neurological improvement. Multivariate analysis was performed to evaluate the effect of premorbid statin use after adjusting for potential confounders.

RESULTS

Seventy‐seven patients fulfilled our inclusion criteria (mean age 66 ± 14, 38 were men) and among them 12 were on statins. The patients who were on statins had a higher recanalization rate (11/12 vs. 33/65, P= .02). This finding was confirmed by logistic regression analysis (odds ratio 17.25, 95% confidence interval 1.67‐177.43). There was no significant difference between the two groups regarding neurological improvement and hemorrhagic transformation.

CONCLUSION

This study demonstrates that patients on statins have higher recanalization rates when they undergo endovascular procedures for acute ischemic stroke.
Carotid Body Tumors: Advantages of Contrast Ultrasound Investigation
Authors: Giannoni Maria F. , Irace Luigi , Vicenzini Edoardo , Massa Rita , Gossetti Bruno , Benedetti‐Valentini Fabrizio
Published: October 2009

Carotid body tumors are rare neoplasms that have to be considered in the evaluation of all lateral neck mass. Early surgical removal has been recommended to avoid possible cranial nerve injury, the most common perioperative complication. Computed tomography (CT) and magnetic resonance imaging (MRA) angiographies are the preferred pre‐operative diagnostic imaging investigations, as well as the 111 In‐pentetreotide scintigraphic scan, whereas the standard ultrasound investigations have poor sensitivity in characterizing of the blood flows of the parenchimal structure of the carotid body tumors. We describe a case of a patient with a carotid body tumor assessed with contrast ultrasonography that clearly improved the quality of the standard color Duplex. This technique may represent a non‐invasive method, easy to use and to repeat, and able to achieve high diagnostic accuracy.
Medical Treatment of Patients with Intracranial Atherosclerotic Disease
Authors: Gomez Camilo R. , Qureshi Adnan I.
Published: October 2009

The medical treatment of patients with symptomatic intracranial atherosclerotic disease (ICAD) is directed toward reducing the risk of new ischemic events. The overall strategy is divided into: (1) prevention of occurrence of intraluminal thrombus, with or without embolism; (2) plaque stabilization and regression; and (3) management of atherogenic risk factors. In patients with ICAD, short‐term and long‐term anticoagulation (compared with aspirin) has not shown to be beneficial. The current guidelines recommend that aspirin monotherapy, the combination of aspirin and extended release dipyridamole, and clopidogrel monotherapy (rather than oral anticoagulants) are all acceptable options in patients with noncardioembolic ischemic stroke and transient ischemic attack. The findings of another pilot trial suggest that symptomatic ICAD is a dynamic lesion and cilostazol may prevent its progression. Overall, the subgroup analysis from randomized trials, provide evidence about benefit of aggressive atherogenic risk factor management among patients with ICAD. Current guidelines recommend statin therapy with intensive lipid‐lowering effects for patients with atherosclerotic ischemic stroke or transient ischemic attack with or without known coronary artery disease to reduce the risk of stroke and cardiovascular events.
Fimag: The United Kingdom Disaster Victim/Forensic Identification Imaging System
Authors: Rutty Guy N. , Robinson Claire , Morgan Bruno , Black Sue , Adams Catherine , Webster Philip
Published: October 2009

Abstract:  Imaging is an integral diagnostic tool in mass fatality investigations undertaken traditionally by plain X‐rays, fluoroscopy, and dental radiography. However, little attention has been given to appropriate image reporting, secure data transfer and storage particularly in relation to the need to meet stringent judicial requirements. Notwithstanding these limitations, it is the risk associated with the safe handling and investigation of contaminated fatalities which is providing new challenges for mass fatality radiological imaging. Mobile multi‐slice computed tomography is an alternative to these traditional modalities as it provides a greater diagnostic yield and an opportunity to address the requirements of the criminal justice system. We present a new national disaster victim/forensic identification imaging system—Fimag—which is applicable for both contaminated and non‐contaminated mass fatality imaging and addresses the issues of judicial reporting. We suggest this system opens a new era in radiological diagnostics for mass fatalities.
Relation between neuritic plaques and depressive state in Alzheimer's disease
Authors: Meynen Gerben , Van Stralen Heleen , Smit Jan H. , Kamphorst Wouter , Swaab Dick F. , Hoogendijk Witte J.G.
Published: October 2009

Meynen G, Van Stralen H, Smit JH, Kamphorst W, Swaab DF, Hoogendijk WJG. Relation between neuritic plaques and depressive state in Alzheimer's disease.

Background:

To investigate for the first time in a prospective study the relationship between depressive state and the neuropathological hallmarks of Alzheimer's disease, using a scale for depressive symptoms in dementia, while controlling for clinical severity of dementia.

Method:

Within the framework of a prospective longitudinal study of depression in Alzheimer's disease, patients with dementia underwent a clinical evaluation every six months during the last years of their lives, using the Cornell scale for depression in dementia to assess depressive symptoms and using the Functional Assessment Staging scale to control for clinical severity of dementia. The brains of 43 Alzheimer patients were obtained. The last clinical evaluations prior to death together with post-mortem neuropathology measures were analysed.

Results:

We found a correlation between the Cornell scores and the sum score for the density of neuritic plaques in the entire cortex (p = 0.027), and even stronger in the temporal cortex (p = 0.012). The observed correlations were independent of sex, age of death, clinical dementia severity and duration of Alzheimer's disease.

Conclusions:

This study shows a positive relationship between depressive state at time of death and the presence of neuritic plaques in Alzheimer's disease, which is independent of the clinical severity of dementia.
Oestradiol Protects Against the Harmful Effects of Fluoride More by Increasing Thiol Group Levels than Scavenging Hydroxyl Radicals
Authors: Dlugosz Anna , Roszkowska Anna , Zimmer Mariusz
Published: October 2009

Abstract:  The aim of the study was to investigate the role of oestrogens in free radical detoxication upon exposure to fluoride. Interactions between xenobiotics and oestrogens need to be investigated, especially as many chemicals interact with the oestrogen receptor. It is still unknown whether free radical‐generating xenobiotics can influence the antioxidative ability of oestradiol (E2). In an in vitro examination of human placental mitochondria, thiobarbituric active reagent species (TBARS), hydroxyl radical (•OH) generation and protein thiol (–SH) groups were detected. 17β‐E2 was examined in physiological (0.15–0.73 nM) and experimental (1–10 µM) concentrations and sodium fluoride (NaF) in concentrations of 6–24 µM. E2 in all the concentrations significantly decreased lipid peroxidation measured as the TBARS level, in contrast to NaF, which increased lipid peroxidation. Lipid peroxidation induced by NaF was decreased by E2. The influence of E2 on •OH generation was not very significant and depended on the E2 concentration. The main mechanism of E2 protection in NaF exposure appeared to be connected with the influence of E2 on thiol group levels, not •OH scavenging ability. The E2 in concentrations 0.44–0.73 nM and 1–10 µM significantly increased the levels of –SH groups, in contrast to NaF, which significantly decreased them. E2 at every concentration reversed the harmful effects of NaF on –SH group levels. No unfavourable interactions in the influence of E2 and NaF on TBARS production, •OH generation, or –SH group levels were observed. The results suggest that postmenopausal women could be more sensitive to NaF‐initiated oxidative stress.
The Effects of Peroral Glycerol on Plasma Osmolarity in Diabetic Patients and Healthy Individuals
Authors: Thornit Dorte Nellemann , Sander Birgit , La Cour Morten , Lund‐Andersen Henrik
Published: October 2009

Abstract:  Glycerol is used as a peroral treatment of increased intraocular and intracranial pressure due to its osmotic effect despite the potential increase in blood pressure and blood glucose. We examined the effects of peroral glycerol in diabetic patients and healthy individuals on blood pressure, capillary glucose, and plasma osmolarity. On two separate days, 15 diabetic patients ingested glycerol in doses of 855 and 1710 mg/kg body weight in a randomised, unmasked sequence. Five healthy individuals ingested a dose of 1710 mg/kg body weight. Mean arterial blood pressure (MAP), capillary glucose (CG) and plasma osmolarity (pOSM) were monitored for 180 min. At baseline, the MAP was comparable between the groups of healthy individuals and diabetic patients (p = 0.55), CG was marginal different (p = 0.06), and pOSM values were significantly different (p = 0.007). Following glycerol ingestion, a transient, non‐significant increase occurred in blood pressure. Maximal ΔCG was approximately 1 mM irrespective of the dose and presence of diabetes (p > 0.1). The pOSM response was analysed with a kinetic model and found independent of the presence of diabetes (p = 0.6). The maximal fitted ΔpOSM was 12.7 and 25.3 mOsm/l in the group of diabetic patients after the low and high dose, respectively, reflecting a dose‐response relationship. Nausea, fatigue and headache were common side effects. In conclusion, peroral glycerol had similar effects on blood glucose, MAP and pOSM in the diabetic patients and healthy individuals. Specific precautions should not be implemented when treating diabetic patients with a single dose up to 1.7 g/kg body weight. A peak increase of 8% in the pOSM within 1 hr can be expected from this dose.
Relationships between the genetic distance of Epichloë festucae isolates and the ergovaline and peramine contents of their Festuca rubra hosts
Authors: Vázquez‐de‐Aldana B.R. , Zabalgogeazcoa I. , Rubio de Casas R. , García‐Ciudad A. , García‐Criado B.
Published: October 2009

In semiarid grasslands of western Spain, plants of Festuca rubra are frequently infected by Epichloë festucae, an endophyte capable of producing the alkaloids ergovaline, toxic to mammals, and peramine, toxic to insects. The objectives of this paper were to estimate the variability in the content of ergovaline and peramine in plants of Festuca rubra from natural populations and to determine the relationship between the genetic distance among Epichloë strains and the alkaloid contents of plants infected by them. The results showed that a significant variation exits in the ergovaline and peramine contents of infected F. rubra plants, and that variation patterns are different for each alkaloid. Ergovaline content showed a significant variation between years. In contrast, most variation observed in the concentration of peramine occurred between populations. Mantel tests, constrained correspondence analysis (CCA) and generalised analysis of molecular variance (GAMOVA) all revealed a significant relationship between the genetic distances among 35 Epichloë isolates, and the differences in peramine content of their host plants. The relationship observed for ergovaline was more ambiguous. This indicates that plants infected by genetically close isolates of Epichloë festucae tend to be similar in terms of peramine content, while the ergovaline content of infected plants seems to be more dependent on external factors. The results of this study suggest that the selection of Epichloë festucae endophytes based on the alkaloid content of their host plants can be a successful strategy to select good or bad producers of peramine, but may not be a reliable method to detect fungal strains associated with particular ergovaline production profiles.