bluuebunny/crossref_metadata_2025 huggingface dataset:
Rhizobial exopolysaccharides: genetic control and symbiotic functions
Authors: Skorupska Anna , Janczarek Monika , Marczak Małgorzata , Mazur Andrzej , Król Jarosław
Published: February 2006

Specific complex interactions between soil bacteria belonging to Rhizobium, Sinorhizobium, Mesorhizobium, Phylorhizobium, Bradyrhizobium and Azorhizobium commonly known as rhizobia, and their host leguminous plants result in development of root nodules. Nodules are new organs that consist mainly of plant cells infected with bacteroids that provide the host plant with fixed nitrogen. Proper nodule development requires the synthesis and perception of signal molecules such as lipochitooligosaccharides, called Nod factors that are important for induction of nodule development. Bacterial surface polysaccharides are also crucial for establishment of successful symbiosis with legumes. Sugar polymers of rhizobia are composed of a number of different polysaccharides, such as lipopolysaccharides (LPS), capsular polysaccharides (CPS or K-antigens), neutral β-1, 2-glucans and acidic extracellular polysaccharides (EPS). Despite extensive research, the molecular function of the surface polysaccharides in symbiosis remains unclear.

This review focuses on exopolysaccharides that are especially important for the invasion that leads to formation of indetermined (with persistent meristem) type of nodules on legumes such as clover, vetch, peas or alfalfa. The significance of EPS synthesis in symbiotic interactions of Rhizobium leguminosarum with clover is especially noticed. Accumulating data suggest that exopolysaccharides may be involved in invasion and nodule development, bacterial release from infection threads, bacteroid development, suppression of plant defense response and protection against plant antimicrobial compounds. Rhizobial exopolysaccharides are species-specific heteropolysaccharide polymers composed of common sugars that are substituted with non-carbohydrate residues. Synthesis of repeating units of exopolysaccharide, their modification, polymerization and export to the cell surface is controlled by clusters of genes, named exo/exs, exp or pss that are localized on rhizobial megaplasmids or chromosome. The function of these genes was identified by isolation and characterization of several mutants disabled in exopolysaccharide synthesis. The effect of exopolysaccharide deficiency on nodule development has been extensively studied. Production of exopolysaccharides is influenced by a complex network of environmental factors such as phosphate, nitrogen or sulphur. There is a strong suggestion that production of a variety of symbiotically active polysaccharides may allow rhizobial strains to adapt to changing environmental conditions and interact efficiently with legumes.
Dietary and other lifestyle correlates of serum folate concentrations in a healthy adult population in Crete, Greece: a cross-sectional study
Authors: Hatzis Christos M , Bertsias George K , Linardakis Manolis , Scott John M , Kafatos Anthony G
Published: February 2006

Background

Folate has emerged as a key nutrient for optimising health. Impaired folate status has been identified as a risk factor for cardiovascular disease, various types of cancers, and neurocognitive disorders. The study aimed at examining the distribution and determinants of serum folate concentrations in a healthy adult population in Crete, Greece.

Methods

A cross-sectional sample of 486 healthy adults (250 men, 236 women) aged 39 ± 14 years, personnel of the Medical School and the University Hospital of Crete in Greece, was examined. Serum folate and vitamin B12 concentrations were measured by microbiological assay, and total homocysteine was determined fluorometrically and by high-pressure liquid chromatography. Lifestyle questionnaires were completed, and nutrient intakes and food consumption were assessed by 24-h dietary recalls. Multivariate analyses were performed using SPSS v10.1.

Results

The geometric mean (95% confidence interval) concentrations of serum folate were 15.6 μmol/l (14.6–16.8) in men and 19.2 μmol/l (17.9–20.7) in women (p < 0.001). Inadequate folate levels (≤7 nmol/l) were present in 6.8% of men and 2.1% of women (p < 0.001). Approximately 76% of men and 87% of women did not meet the reference dietary intake for folate (400 μg/day). Serum folate was inversely related to total homocysteine levels (p < 0.001). Increased tobacco and coffee consumption were associated with lower folate concentrations (p < 0.05 for both) but these associations disappeared after controlling for nutrient intakes. In multivariate analysis, intakes of MUFA, fibre, calcium, magnesium, folate, and vitamins A, E, C, B1, and B6 were positively associated with serum folate. Consumption of potatoes, legumes, fruits, and vegetables were favourably related to the serum folate status.

Conclusion

Serum folate concentrations were associated with various demographic, lifestyle and dietary factors in healthy Cretan adults. Large-scale epidemiological studies should be conducted within the general Greek adult population to assess the prevalence of impaired folate status and further examine associations with dietary patterns and chronic disease risk. Considering the importance of folate in health maintenance, it is important to increase the public's awareness of modifiable lifestyle patterns and diet and tobacco use in particular, which may be associated with improved folate status.
HIV/AIDS prevalence and behaviour in drug users and pregnant women in Kashgar Prefecture: Case report
Authors: Mingjian Ni , Wheeler KM , Cheng J , Yonghai Dong , Chen W , Fitzwarryne C , Wang J
Published: February 2006

Second Generation sub-population HIV Surveillance was undertaken in Kashgar City and Shache County, Xinjiang, Peoples Republic of China between December 2003 and January 2004, targeting injecting and mixed method drug users and pregnant and postnatal women. The study aimed to determine the extent to which the epidemic is shifting from a concentrated stage to a more generalised epidemic. One hundred and forty two (142) exclusively injecting drug users (66) and mixed method drug users (injecting and non-injecting-76) participated in this survey. Eight hundred and two (802) pregnant and postnatal women participated in the survey. In Kashgar City and Shache County the serum prevalence of HIV amongst injecting drug users was 56.06%, for mixed method drug users 48.68% and 0.38% in pregnant women. In Shache County HIV infection rates were significantly lower in drug user groups and amongst pregnant and post-natal women, at 2.22% and 0% respectively. The behavioral survey indicated that 15% of injecting drug users have shared needles (however sero prevalence and knowledge in relation to access to clean needles and syringes suggests that this may not reflect the actual situation). Knowledge of prevention of transmission strategies (not sharing needles and condom utilisation) is similar between both groups at 60–70%. However it appears that this knowledge has not significantly impacted on behavior such as needle sharing and condom utilisation. In Kashgar City and Shache County there have been very few interventions to support HIV/AIDS prevention, care and control. The results from this survey will inform future directions and the development and implementation of targeted interventions including targeted information dissemination and harm reduction strategies.

This survey was funded by the Xinjiang HIV/AIDS Prevention and Care Project, a bilateral project jointly implemented by the Government of the People's Republic of China and the Government of Australia.
Nav 1.8-Null Mice Show Stimulus-Dependent Deficits in Spinal Neuronal Activity
Authors: Matthews Elizabeth A , Wood John N , Dickenson Anthony H
Published: February 2006

Background

The voltage gated sodium channel Nav 1.8 has a highly restricted expression pattern to predominantly nociceptive peripheral sensory neurones. Behaviourally Nav 1.8-null mice show an increased acute pain threshold to noxious mechanical pressure and also deficits in inflammatory and visceral, but not neuropathic pain. Here we have made in vivo electrophysiology recordings of dorsal horn neurones in intact anaesthetised Nav 1.8-null mice, in response to a wide range of stimuli to further the understanding of the functional roles of Nav 1.8 in pain transmission from the periphery to the spinal cord.

Results

Nav 1.8-null mice showed marked deficits in the coding by dorsal horn neurones to mechanical, but not thermal, -evoked responses over the non-noxious and noxious range compared to littermate controls. Additionally, responses evoked to other stimulus modalities were also significantly reduced in Nav 1.8-null mice where the reduction observed to pinch > brush. The occurrence of ongoing spontaneous neuronal activity was significantly less in mice lacking Nav 1.8 compared to control. No difference was observed between groups in the evoked activity to electrical activity of the peripheral receptive field.

Conclusion

This study demonstrates that deletion of the sodium channel Nav 1.8 results in stimulus-dependent deficits in the dorsal horn neuronal coding to mechanical, but not thermal stimuli applied to the neuronal peripheral receptive field. This implies that Nav 1.8 is either responsible for, or associated with proteins involved in mechanosensation.
Efficacy of low level laser therapy on neurosensory recovery after injury to the inferior alveolar nerve
Authors: Ozen Tuncer , Orhan Kaan , Gorur Ilker , Ozturk Adnan
Published: February 2006

Background

The most severe complication after the removal of mandibular third molars is injury to the inferior alveolar nerve or the lingual nerve. These complications are rather uncommon (0.4% to 8.4%) and most of them are transient. However, some of them persist for longer than 6 months, which can leave various degrees of long-term permanent disability. While several methods such as pharmacologic therapy, microneurosurgery, autogenous and alloplastic grafting can be used for the treatment of long-standing sensory aberrations in the inferior alveolar nerve, there are few reports regarding low level laser treatment. This paper reports the effects of low level laser therapy in 4 patients with longstanding sensory nerve impairment following mandibular third molar surgery.

Methods

Four female patients had complaints of paresthesia and dysesthesia of the lip, chin and gingiva, and buccal regions. Each patient had undergone mandibular third molar surgery at least 1 year before. All patients were treated with low level laser therapy. Clinical neurosensory tests (the brush stroke directional discrimination test, 2-point discrimination test, and a subjective assessment of neurosensory function using a visual analog scale) were used before and after treatment, and the responses were plotted over time.

Results

When the neurosensory assessment scores after treatment with LLL therapy were compared with the baseline values prior to treatment, there was a significant acceleration in the time course, as well as in the magnitude, of neurosensory return. The VAS analysis revealed progressive improvement over time.

Conclusion

Low level laser therapy seemed to be conducive to the reduction of long-standing sensory nerve impairment following third molar surgery. Further studies are worthwhile regarding the clinical application of this treatment modality.
Cytokine polymorphisms influence treatment outcomes in SLE patients treated with antimalarial drugs
Authors: López Patricia , Gómez Jesús , Mozo Lourdes , Gutiérrez Carmen , Suárez Ana
Published: February 2006

Antimalarial agents have been widely used as disease-modifying antirheumatic drugs in the treatment of systemic lupus erythematosus (SLE) and other rheumatological diseases, although their mechanism of action has not yet been fully defined. It is known, however, that effective response to treatment is variable among patients. Thus, the identification of genetic predictors of treatment response would provide valuable information for therapeutic intervention. The aim of the present study was to analyze the effect of antimalarial treatment on tumor necrosis factor (TNF)α serum levels and evaluate the possible influence of TNFα and IL-10 functional genetic polymorphisms on the response to antimalarial drugs. To this end, TNFα serum levels were quantified in 171 SLE patients and 215 healthy controls by ELISA techniques and polymorphisms at positions -1,082 and -308 of the IL-10 and TNFα gene promoterswere determined by PCR amplification followed by hybridization with fluorescent-labeled allele-specific probes in 192 SLE patients and 343 matched controls. Data were related to clinical features and treatment at the time of sampling and during the course of the disease. Results showed a significantly higher amount of serum TNFα in the entire SLE population compared with controls. However, TNFα serum levels correlated negatively with the use of antimalarial treatment during at least three months before sampling. Patients under single or combined treatment with these drugs had TNFα serum levels similar to healthy controls, whereas untreated patients and those under corticosteroid or immunosuppressive therapies had increased amounts of this cytokine. This suggests, however, that antimalarial-mediated inhibition of TNFα was only significant in patients who were genetically high TNFα or low IL-10 producers. In addition, evaluation of SLE patients administered antimalarial drugs for three or more years who did not require any other specific SLE treatment indicates that patients with the combined genotype low IL-10/high TNFα are the best responders to antimalarial therapy, developing mild disease with a good course under this treatment. In conclusion, we proposed that an antimalarial-mediated downregulation of TNFα levels in SLE patients is influenced by polymorphisms at IL-10 and TNFα promoters. Our results may thus find important clinical application through the identification of patients who are the most likely to benefit from antimalarial therapy.
Lactate versus non-lactate metabolic acidosis: a retrospective outcome evaluation of critically ill patients
Authors: Gunnerson Kyle J , Saul Melissa , He Shui , Kellum John A
Published: February 2006

Introduction

Acid–base abnormalities are common in the intensive care unit (ICU). Differences in outcome exist between respiratory and metabolic acidosis in similar pH ranges. Some forms of metabolic acidosis (for example, lactate) seem to have worse outcomes than others (for example, chloride). The relative incidence of each type of disorder is unknown. We therefore designed this study to determine the nature and clinical significance of metabolic acidosis in critically ill patients.

Methods

An observational, cohort study of critically ill patients was performed in a tertiary care hospital. Critically ill patients were selected on the clinical suspicion of the presence of lactic acidosis. The inpatient mortality of the entire group was 14%, with a length of stay in hospital of 12 days and a length of stay in the ICU of 5.8 days.

Results

We reviewed records of 9,799 patients admitted to the ICUs at our institution between 1 January 2001 and 30 June 2002. We selected a cohort in which clinicians caring for patients ordered a measurement of arterial lactate level. We excluded patients in which any necessary variable required to characterize an acid–base disorder was absent. A total of 851 patients (9% of ICU admissions) met our criteria. Of these, 548 patients (64%) had a metabolic acidosis (standard base excess < -2 mEq/l) and these patients had a 45% mortality, compared with 25% for those with no metabolic acidosis (p < 0.001). We then subclassified metabolic acidosis cases on the basis of the predominant anion present (lactate, chloride, or all other anions). The mortality rate was highest for lactic acidosis (56%); for strong ion gap (SIG) acidosis it was 39% and for hyperchloremic acidosis 29% (p < 0.001). A stepwise logistic regression model identified serum lactate, SIG, phosphate, and age as independent predictors of mortality.

Conclusion

In critically ill patients in which a measurement of lactate level was ordered, lactate and SIG were strong independent predictors of mortality when they were the major source of metabolic acidosis. Overall, patients with metabolic acidosis were nearly twice as likely to die as patients without metabolic acidosis.
Dopexamine and norepinephrine versus epinephrine on gastric perfusion in patients with septic shock: a randomized study [NCT00134212]
Authors: Seguin Philippe , Laviolle Bruno , Guinet Patrick , Morel Isabelle , Mallédant Yannick , Bellissant Eric
Published: February 2006

Introduction

Microcirculatory blood flow, and notably gut perfusion, is important in the development of multiple organ failure in septic shock. We compared the effects of dopexamine and norepinephrine (noradrenaline) with those of epinephrine (adrenaline) on gastric mucosal blood flow (GMBF) in patients with septic shock. The effects of these drugs on oxidative stress were also assessed.

Methods

This was a prospective randomized study performed in a surgical intensive care unit among adults fulfilling usual criteria for septic shock. Systemic and pulmonary hemodynamics, GMBF (laser-Doppler) and malondialdehyde were assessed just before catecholamine infusion (T0), as soon as mean arterial pressure (MAP) reached 70 to 80 mmHg (T1), and 2 hours (T2) and 6 hours (T3) after T1. Drugs were titrated from 0.2 μg kg-1 min-1 with 0.2 μg kg-1 min-1 increments every 3 minutes for epinephrine and norepinephrine, and from 0.5 μg kg-1 min-1 with 0.5 μg kg-1 min-1 increments every 3 minutes for dopexamine.

Results

Twenty-two patients were included (10 receiving epinephrine, 12 receiving dopexamine–norepinephrine). There was no significant difference between groups on MAP at T0, T1, T2, and T3. Heart rate and cardiac output increased significantly more with epinephrine than with dopexamine–norepinephrine, whereas. GMBF increased significantly more with dopexamine–norepinephrine than with epinephrine between T1 and T3 (median values 106, 137, 133, and 165 versus 76, 91, 90, and 125 units of relative flux at T0, T1, T2 and T3, respectively). Malondialdehyde similarly increased in both groups between T1 and T3.

Conclusion

In septic shock, at doses that induced the same effect on MAP, dopexamine–norepinephrine enhanced GMBF more than epinephrine did. No difference was observed on oxidative stress.
Idiomatic Syntactic Constructions and Language Learning
Authors: Kaschak Michael P. , Saffran Jenny R.
Published: February 2006

This article explores the influence of idiomatic syntactic constructions (i.e., constructions whose phrase structure rules violate the rules that underlie the construction of other kinds of sentences in the language) on the acquisition of phrase structure. In Experiment 1, participants were trained on an artificial language generated from hierarchical phrase structure rules. Some participants were given exposure to an idiomatic construction (IC) during training, whereas others were not. Under some circumstances, the presence of an idiomatic construction in the input aided learners in acquiring the phrase structure of the language. Experiment 2 provides a replication of the first experiment and extends the findings by showing that idiomatic constructions that strongly violate the predictive dependencies that define the phrase structure of the language do not aid learners in acquiring the structure of the language. Together, our data suggest that (a) idiomatic constructions aid learners in acquiring the phrase structure of a language by highlighting relevant structural elements in the language, and (b) such constructions are useful cues to learning to the extent that learners can keep their knowledge of the idiomatic construction separate from their knowledge of the rest of the language.
The Role of Functionality in the Mental Representations of Engineering Students: Some Differences in the Early Stages of Expertise
Authors: Moss Jarrod , Kotovsky Kenneth , Cagan Jonathan
Published: February 2006

As engineers gain experience and become experts in their domain, the structure and content of their knowledge changes. Two studies are presented that examine differences in knowledge representation among freshman and senior engineering students. The first study examines recall of mechanical devices and chunking of components, and the second examines whether seniors represent devices in a more abstract functional manner than do freshmen. The most prominent differences between these 2 groups involve their representation of the functioning of groups of electromechanical components and how these groups of components interact to produce device behavior. Seniors are better able to construct coherent representations of devices by focusing on the function of sets of components in the device. The findings from these studies highlight some ways in which the structure and content of mental representations of design knowledge differ during the early stages of expertise acquisition.
Modeling Recognition Memory Using the Similarity Structure of Natural Input
Authors: Lacroix Joyca P. W. , Murre Jaap M. J. , Postma Eric O. , van den Herik H. Jaap
Published: February 2006

The natural input memory (NIM) model is a new model for recognition memory that operates on natural visual input. A biologically informed perceptual preprocessing method takes local samples (eye fixations) from a natural image and translates these into a feature‐vector representation. During recognition, the model compares incoming preprocessed natural input to stored representations. By complementing the recognition memory process with a perceptual front end, the NIM model is able to make predictions about memorability based directly on individual natural stimuli. We demonstrate that the NIM model is able to simulate experimentally obtained similarity ratings and recognition memory for individual stimuli (i.e., face images).
Deferred Interpretations: Why Starting Dickens is Taxing but Reading Dickens Isn't
Authors: McElree Brian , Frisson Steven , Pickering Martin J.
Published: February 2006

Comprehenders often need to go beyond conventional word senses to obtain an appropriate interpretation of an expression. We report an experiment examining the processing of standard metonymies (The gentleman read Dickens) and logical metonymies (The gentleman began Dickens), contrasting both to the processing of control expressions with a conventional interpretation (The gentleman met Dickens). Eye movement measures during reading indicated that standard (producer‐for‐product) metonymies were not more costly to interpret than conventional expressions, but logical metonymies were more costly to interpret than both standard metonymies and conventional expressions. These results indicate that constructing alternative senses is sometimes taxing and that not all types of deferred interpretations are processed in the same way. The results suggest that a critical factor in determining the attendant cost of constructing alternative senses is whether compositional operations must generate unexpressed semantic structure to realize an extended sense of an expression.
Animal Foraging and the Evolution of Goal‐Directed Cognition
Authors: Hills Thomas T.
Published: February 2006

Foraging‐ and feeding‐related behaviors across eumetazoans share similar molecular mechanisms, suggesting the early evolution of an optimal foraging behavior called area‐restricted search (ARS), involving mechanisms of dopamine and glutamate in the modulation of behavioral focus. Similar mechanisms in the vertebrate basal ganglia control motor behavior and cognition and reveal an evolutionary progression toward increasing internal connections between prefrontal cortex and striatum in moving from amphibian to primate. The basal ganglia in higher vertebrates show the ability to transfer dopaminergic activity from unconditioned stimuli to conditioned stimuli. The evolutionary role of dopamine in the modulation of goal‐directed behavior and cognition is further supported by pathologies of human goal‐directed cognition, which have motor and cognitive dysfunction and organize themselves, with respect to dopaminergic activity, along the gradient described by ARS, from perseverative to unfocused. The evidence strongly supports the evolution of goal‐directed cognition out of mechanisms initially in control of spatial foraging but, through increasing cortical connections, eventually used to forage for information.
Formalization and Analysis of Reasoning by Assumption
Authors: Bosse Tibor , Jonker Catholijn M. , Treur Jan
Published: February 2006

This article introduces a novel approach for the analysis of the dynamics of reasoning processes and explores its applicability for the reasoning pattern called reasoning by assumption. More specifically, for a case study in the domain of a Master Mind game, it is shown how empirical human reasoning traces can be formalized and automatically analyzed against dynamic properties they fulfill. To this end, for the pattern of reasoning by assumption a variety of dynamic properties have been specified, some of which are considered characteristic for the reasoning pattern, whereas some other properties can be used to discriminate among different approaches to the reasoning. These properties have been automatically checked for the traces acquired in experiments undertaken. The approach turned out to be beneficial from two perspectives. First, checking characteristic properties contributes to the empirical validation of a theory on reasoning by assumption. Second, checking discriminating properties allows the analyst to identify different classes of human reasoners.
Global Profiles of Gene Expression Induced by Adrenocorticotropin in Y1 Mouse Adrenal Cells
Authors: Schimmer Bernard P. , Cordova Martha , Cheng Henry , Tsao Andrew , Goryachev Andrew B. , Schimmer Aaron D. , Morris Quaid
Published: February 2006

ACTH regulates the steroidogenic capacity, size, and structural integrity of the adrenal cortex through a series of actions involving changes in gene expression; however, only a limited number of ACTH-regulated genes have been identified, and these only partly account for the global effects of ACTH on the adrenal cortex. In this study, a National Institute on Aging 15K mouse cDNA microarray was used to identify genome-wide changes in gene expression after treatment of Y1 mouse adrenocortical cells with ACTH. ACTH affected the levels of 1275 annotated transcripts, of which 46% were up-regulated. The up-regulated transcripts were enriched for functions associated with steroid biosynthesis and metabolism; the down- regulated transcripts were enriched for functions associated with cell proliferation, nuclear transport and RNA processing, including alternative splicing. A total of 133 different transcripts, i.e. only 10% of the ACTH-affected transcripts, were represented in the categories above; most of these had not been described as ACTH-regulated previously. The contributions of protein kinase A and protein kinase C to these genome-wide effects of ACTH were evaluated in microarray experiments after treatment of Y1 cells and derivative protein kinase A-defective mutants with pharmacological probes of each pathway. Protein kinase A-dependent signaling accounted for 56% of the ACTH effect; protein kinase C-dependent signaling accounted for an additional 6%. These results indicate that ACTH affects the expression profile of Y1 adrenal cells principally through cAMP- and protein kinase A- dependent signaling. The large number of transcripts affected by ACTH anticipates a broader range of actions than previously appreciated.
Peroxisomal Multifunctional Protein 2 Is Essential for Lipid Homeostasis in Sertoli Cells and Male Fertility in Mice
Authors: Huyghe Steven , Schmalbruch Henning , De Gendt Karel , Verhoeven Guido , Guillou Florian , Van Veldhoven Paul P. , Baes Myriam
Published: February 2006

Inactivation of peroxisomal β-oxidation in mice, by knocking out multifunctional protein-2 (MFP-2; also called d-bifunctional enzyme), causes male infertility. In the testis, extensive accumulations of neutral lipids were observed in Sertoli cells, beginning in prepubertal mice and evolving in complete testicular atrophy by the age of 4 months. Spermatogenesis was already severely affected at the age of 5 wk, and pre- and postmeiotic germ cells gradually disappeared from the tubuli seminiferi. Based on cytochemical stainings and biochemical analyses, the lipid droplets consisted of cholesteryl esters and neutral glycerolipids. Furthermore, peroxisomal β-oxidation substrates, such as very-long-chain fatty acids and pristanic acid, accumulated in the testis, whereas the concentration of docosapentaenoic acid, a polyunsaturated fatty acid and peroxisomal β-oxidation product, was reduced. The testicular defects were also present in double MFP-2/peroxisome proliferator-activated receptor-α knockout mice, ruling out the possibility that they were mediated through the activation of this nuclear receptor. Immunoreactivity for peroxisomal proteins, including MFP-2, was detected in Sertoli cells as well as in germ cells and Leydig cells. The pivotal role of peroxisomal metabolism in Sertoli cells was also demonstrated by generating mice with a Sertoli cell-selective elimination of peroxisomes through cell type-specific inactivation of the peroxin 5 gene. These mice also developed lipid inclusions and were infertile, and their testes fully degenerated by the age of 4 months. In conclusion, the present data demonstrate that peroxisomal β-oxidation is essential for lipid homeostasis in the testis and for male fertility.
Pretargeting For The Implantation Of Stimulation Electrodes Into The Subthalamic Nucleus:A Comparative Study Of Magnetic Resonance Imaging And Ventriculography
Authors: Breit Sorin , LeBas Jean-Francois , Koudsie Adnan , Schulz Jo¨rg , Benazzouz Abdelhamid , Pollak Pierre , Benabid Alim-Louis
Published: February 2006

OBJECTIVE:

The optimal imaging modality for preoperative targeting of the subthalamic nucleus (STN) for high-frequency stimulation is controversially discussed. Commonly used methods were stereotactic magnetic resonance imaging (MRI), stereotactic ventriculography, and fusion between MRI and stereotactic computer tomography. All of these techniques not only have their own advantages but also specific limitations and drawbacks. The purpose of this study was to evaluate the accuracy of the preoperative MRI targeting as compared with ventriculography in terms of both the STN target as well as the internal landmarks.

METHODS:

Thirty patients with Parkinson's disease who underwent bilateral surgery for STN-high-frequency stimulation received both stereotactic ventriculography and stereotactic MRI. The theoretical target was determined by each of these two imaging modalities. The final electrode placement was performed after extensive electrophysiological evaluation using microrecording and microstimulation. The real target was assumed to be given by the electrode contact with the best clinical result assessed by the United Parkinson's Disease Rating Scale in the postoperative follow-up. In addition, the coordinates of the two landmarks, anterior commissure and posterior commissure, were determined using both imaging methods.

RESULTS:

The mean targeting error was 4.1 ± 1.7 mm (mean ± standard deviation) for MRI and 2.4 ± 1.1 mm for ventriculography (P < 0.0001). The mean target mismatch between the two imaging methods was 2.9 ± 1.2 mm. The length of the anterior commissure-posterior commissure distance differed significantly (P < 0.0001) between MRI (27.6 ± 1.6 mm) and ventriculography (25.0 ± 1.3 mm). The mismatch was mainly induced by an anterior diplacement of the anterior commissure by 1.9 ± 2.2 mm (P < 0.0001) in MRI determination, as compared with ventriculography.

CONCLUSION:

Our findings show that the indirect targeting of the STN using coordinates based on radiological landmarks is more accurate than the direct targeting using anatomic visualization of the target structure. Regardless of the imaging procedure, electrophysiological mapping is required for optimal electrode placement, although in 20% of cases, the target determined by MRI falls out of the radius explored by electrophysiology.
Endoscopic Resection of Hypothalamic Hamartoma Using a Novel Variable Aspiration Tissue Resector
Authors: Lekovic Gregory P. , Gonzalez L. Fernando , Feiz-Erfan Iman , Rekate Harold L.
Published: February 2006

OBJECTIVE:

We present a novel variable aspiration tissue resector for use with neuroendoscopy.

METHODS:

Two patients, 4 and 14 years old, respectively, presented with intractable gelastic seizures refractory to maximal medical therapies. Magnetic resonance imaging showed mass lesions of the third ventricle consistent with hypothalamic hamartoma.

RESULTS:

The patients underwent magnetic resonance imaging wand-guided endo-scopic resection of the tumor with the Suros novel variable aspiration tissue resector. There were no device-associated complications or adverse events. The hamartoma was disconnected in one patient, and gross total resection was achieved in the other.

CONCLUSION:

Endoscopy for tumor resection is still frustrated by the lack of surgical tools, such as ultrasonic aspirators, comparable with those available for use during open procedures. The variable-aspiration tissue resector reported here can be used to resect tumor tissue safely. These two cases demonstrate that gross total resection of small hypothalamic hamartomas is feasible with minimal morbidity through an endo-scopic approach.
The Occipital Artery:Amicroanatomical Study
Authors: Alvernia Jorge E. , Fraser Kenneth , Lanzino Giuseppe
Published: February 2006

OBJECTIVE:

We performed a systematic microanatomical study of the occipital artery (OA) and its branches to describe the course, diameter, and branches of this vessel as well as the presence and pattern of anastomotic channels between the OA and the vertebral artery.

METHODS:

Twelve occipital arteries (6 adult cadaveric heads injected with colored latex) were studied using the surgical microscope. Particular attention was given to the course and branching pattern of the artery as well as the presence and type of anastomotic channels between the occipital artery and vertebral artery.

RESULTS:

Based upon anatomical considerations, the course of the occipital artery was divided into three segments. The first, or digastric segment, extends from the origin to the exit off the occipital groove of the mastoid process. The second segment, or suboccipital, extends from the occipital groove to the superior nuchal line. The third, or terminal segment, corresponds to the subgaleal segment just above the superior nuchal line up to the vertex. Two main descending branches of the second segment or suboccipital were identified. The superficial descending branch (SDB) runs between the splenium capitis and semispinalis capitis while the deep descending branch (DDB) enters the suboccipital triangle. Anastomotic vessels between one of these two descending branches and branches of the vertebral artery were found in 11 out of the 12 OAs dissected (91%).

CONCLUSION:

Detailed knowledge of the OA anatomy is helpful in choosing this vessel as a donor for extra-intracranial bypasses. More importantly, knowledge and understanding of the type and pattern of anastomoses between the OA and the vertebral artery are critical to avoid disastrous complications (i.e., posterior circulation stroke) during embolization of vascular or neoplastic processes fed by distal OA branches.
Affinity purification of eukaryotic 48S initiation complexes
Authors: LOCKER NICOLAS , EASTON LAURA E. , LUKAVSKY PETER J.
Published: February 2006

In vitro assembly of translation initiation complexes from higher eukaryotes requires purification of ribosomal subunits, eukaryotic initiation factors, and initiator tRNA from natural sources, and therefore yields only limited material for functional and structural studies. Here we describe a robust, affinity chromatography-based purification of eukaryotic 48S initiation complexes from rabbit reticulocyte lysate (RRL), which significantly reduces the number of individual purification steps. Hybrid RNA molecules, consisting of either a canonical 5′ UTR or an internal ribosome entry site (IRES) RNA followed by a short open reading frame and a streptomycin aptamer sequence, are incubated in RRL to form 48S complexes. The assembly reaction is then applied to a dihydrostreptomycin-sepharose column; bound complexes are washed and specifically eluted upon addition of streptomycin. The eluted fractions are further purified by centrifugation through a sucrose density gradient to yield pure 48S particles. Using this purification scheme, properly assembled IRES-mediated as well as canonical 48S complexes were purified in milligram quantities.
RNA-associated protein 55 (RAP55) localizes to mRNA processing bodies and stress granules
Authors: YANG WEI-HONG , YU JIANG HONG , GULICK TOD , BLOCH KENNETH D. , BLOCH DONALD B.
Published: February 2006

The mRNA processing body (P-body) is a cellular structure that has an important role in mRNA degradation. P-bodies have also been implicated in RNAi-mediated post-transcriptional gene silencing. The objective of this study was to identify and characterize novel components of the mammalian P-body. Approximately 5% of patients with the autoimmune disease primary biliary cirrhosis have antibodies directed against this structure. Serum from one of these patients was used to identify a cDNA encoding RAP55, a 463–amino acid protein. RAP55 colocalized with previously identified P-body components DCP1a and Ge-1. RAP55 contains an N-terminal Sm-like domain and two C-terminal RGG-rich domains separated by an FDF motif. The two RGG domains and the FDF domain were necessary and sufficient to target the protein to P-bodies. A fragment of RAP55 consisting of the FDF and the second RGG domains did not localize to P-bodies, but was able to displace other P-body components from this structure. After cells were subjected to arsenite-induced stress, RAP55 was detected in TIA-containing stress granules. The second RGG domain was necessary and sufficient for stress granule localization. siRNA-mediated knock-down of RAP55 resulted in loss of P-bodies, suggesting that RAP55 acts prior to the 5′-decapping step in mRNA degradation. The results of this study show that RAP55 is a component of P-bodies in cells at rest and localizes in stress granules in arsenite-treated cells. RAP55 may serve to shuttle mRNAs between P-bodies and stress granules.
Annealing effects, anomalous dielectric properties and conductivity of As-diluted lead phosphate Pb3(P1–xAsxO4)2
Authors: Baranov Anatolii I. , Bismayer Ulrich
Published: February 2006

The influence of annealing (thermal treatment) in different atmospheres on the conductivity and dielectric properties of As-diluted lead phosphate Pb3(P
1–x
As
x
O4)2was studied. The anomalous low frequency dielectric behavior of these crystals was found to be related to their conductive properties. A model invoking the dissociation of polar impurity complexes is proposed in order to explain the observed giant dielectric maxima and their strong frequency dispersion. It was found that extrinsic proton conductivity dominates the dielectric properties in the temperature range 350–900 K in Pb3(P
1–x
As
x
O4)2 and that annealing in wet atmosphere increases the protonic conductivity by more than one order of magnitude.
The transformation mechanism of the sodalite- to the melilite-topology: Thermal expansion and decomposition of bicchulite-type to melilite-type compounds
Authors: Peters Lars , Knorr Karsten , Katzke Hannelore , Knapp Michael , Depmeier Wulf
Published: February 2006

The mineral bicchulite, |Ca8(OH)8|[Al8Si4O24]-SOD, has the sodalite-(SOD-)type structure. At elevated temperatures it decomposes into gehlenite, Ca2Al2SiO7 (melilite-type structure), and water (vapour). We report on the thermal expansion of two bicchulite-type compounds, the mineral bicchulite up to T = 740 K and |Ca6Eu2(OH)8|[Al10Si2O24]-SOD up to T = 1025 K. The expansion mechanism is described. In
situ X-ray powder diffraction experiments were performed to evaluate the thermal decomposition of |Ca6Eu2(OH)8|[Al10Si2O24]-SOD into 4 (Ca1.5Eu0.5)T
1[T
2
2O7] and 4 H2O, with T
i = Al or Si in a ratio of 5 : 1. A structural mechanism for the transformation from the sodalite to the melilite topology is proposed, based on geometrical considerations.
The crystal structure of natural 33R moissanite from Tibet
Authors: Lee Jiann-Shing , Yu Shu-Cheng , Tung Shu-Fang , Bai Wen-Ji , Yang Jing-Sui , Fang Qing-Song , Zhang Zeming
Published: February 2006

The crystal structure of the natural 33R moissanite, recovered as inclusions in chromitites from Luobusa harzburgite in Tibet, was determined from X-ray diffraction data collection by a Nonius CAD-4 four-circle diffractometer. The crystal is trigonal in symmetry with a space group of R3m. Identical to the synthetic specimen, the cell parameters are a = 3.076, c = 83.12 Å for the natural sample. Full-matrix least-squares refinement of the structure, including anisotropic displacement parameters, gave the final R factor of 4.80%.

The bond angles and tetrahedral angle variance of the present crystal structure show that the tetrahedra are quite regular in geometry. The distance between two adjacent c double layers, 2.517 ± 0.001 Å, is slightly shorter than the average h–c distance of 2.523 ± 0.001 Å. With 36% hexagonal double layers, the present 33R moissanite is inferred to crystallize at high temperature condition and thus come from a depth beneath Earth’s crust. The structure refinements of this work indicate that the present moissanite exhibits smaller thermal displacement parameters. Most of the Si—C bond distances parallel to the c axis are longer than other distances. This result as well as longer bond distances of Si—C along c axis may be indicative of a weaker covalent bonding force along this direction.
Structure, phase transitions and dielectric properties of a new inclusion compound of bis-thiourea pyridinium nitrate salt
Authors: Maluszýnska Hanna , Czarnecki Piotr
Published: February 2006

A structure of a new inclusion compound of bis-thiourea pyridinium nitrate salt C5H6N+NO3
- 2[CH4N2S] was determined by single-crystal X-ray diffraction method at 293 K, 250 K and 150 K. In high temperature phase the compound crystallizes in orthorhombic system, the two low-temperature phases are monoclinic. The sequence of phases is: Pbnm → P21/c → P21. In the orthorhombic form (I) the a axis is doubled in respect to the monoclinic forms and pyridinium and nitrate ions are partially disordered. Both low-temperature monoclinic phases (II) and (III) are ordered but twinned by pseudo-merohedry. In all three phases the host lattice is built of ribbons of hydrogen-bonded thiourea molecules and nitrate anions forming channels in which the guests pyridinium cations are located. Each ribbon consists of two crystallographically independent thiourea molecules and nitrate ions. Four ribbons form a channel parallel to the c axis with approximately square cross-section. In the channel there is a stack of pyridinium cations, which planes form an inclination angle with the channel axis. The angle varies from about 90° in disordered phase I to 60° in well ordered phase (III).

The dielectric spectroscopy measurements were performed on the polycrystalline sample with HP-4291A impedance analyser in the frequency range 1 MHz–1 GHz. The dielectric measurements reveal that two phase transitions occur at T
1 = 287 K and at T
2 = 217 K. The phase transition at T
2 = 287 K is of the first order with the thermal hysteresis of 10 K at cooling and heating. The phase transition at 217 K is of the second order and the dielectric anomaly suggests the ferroelectric-paraelectric phase transition. The dielectric relaxation observed below T
2 are caused by the pyridinium cation reorientation. The dielectric relaxation time changes with the temperature according to Arrhenius low and the activation energy of the relaxation process is about 14 kJ/mol.
Self-association and stereochemistry study of (5R)-4-methyl-5-phenyl-1,3,4-oxadiazinan-2-one
Authors: Rodrigues Alessandro , Olivato Paulo R. , Zukerman-Schpector Julio , Rittner Roberto
Published: February 2006

C10H12N2O2, M
r = 191.21, P21, a = 5.5771(7), b = 27.841(3), c = 6.906(1) Å, β = 111.937(9)°, Z = 4, R
1 = 0.0462. The two independent molecules in the asymmetric unit are linked through two very strong quasi centro-symmetric hydrogen bonds. The oxadiazinone rings, of both molecules, show the pyramidal inversion at N-4 nitrogen, thus resulting in a C(R)N(S)—C(R)N(R) diastereomeric pair. The analysis of the IR N-H stretching band (in the solid and in carbon tetrachloride solution) and the 13C NMR experiment at low temperature are in agreement with the X-ray crystal structure.
Cleft Palate and Keratoconus in a Child Affected by Fetal Alcohol Syndrome: An Accidental Association?
Authors: Pensiero Stefano , Manna Francesco , Michieletto Paola , Perissutti Paolo
Published: February 2006

This report describes the case of a 9-year-old girl affected by fetal alcohol syndrome who presented at birth with blepharophimosis and a cleft palate, which was submitted to surgery. She was referred to our hospital for a visual acuity reduction, where a diagnosis of keratoconus was made. This case highlights the rarity of the association between fetal alcohol syndrome and cleft palate and the previously unreported association involving fetal alcohol syndrome–keratoconus and cleft palate–keratoconus.
Testing Causal Mechanisms of Nonsyndromic Craniosynostosis Using Path Analysis of Cranial Contents in Rabbits with Uncorrected Craniosynostosis
Authors: Fellows-Mayle Wendy , Hitchens T. Kevin , Simplaceanu Elena , Horner Joyce , Barbano Timothy , Losee Joseph E. , Losken H. Wolfgang , Siegel Michael I. , Mooney Mark P.
Published: February 2006

Objective:

Various causal mechanisms of familial nonsyndromic craniosynostosis have been presented. One hypothesis suggests that overproduction of bone at the suture is the primary origin of craniosynostosis, which affects brain and cranial growth secondarily through altered intracranial pressure (Primary Suture Fusion Model). Other hypotheses suggest that decreased cranial base growth or abnormal brain growth are the primary cause of craniosynostosis (Cranial Base, Brain Parenchyma Models, respectively). This study was designed to investigate which model best describes neurocranial changes associated with craniosynostosis in a rabbit model through multivariate path analysis.

Design:

Serial magnetic resonance imaging scans and intracranial pressure measurements were obtained at 10, 25, and 42 days of age from 18 rabbits: six controls, six with delayed-onset synostosis, and six with early-onset synostosis. Five variables were collected from each rabbit: calvarial thickness at the affected suture, cranial base length, brain volume, cerebrospinal fluid volume, and intracranial pressure. This data set was used to test causal pathway relationships generated by the proposed models. Goodness of fit was measured by experimental group for each model.

Results:

Primary Suture Fusion Model best explained the variables in both delayed-onset and early-onset synostotic rabbits (Goodness of fit = 93%, 97%, respectively). Cranial Base Model (Goodness of fit = 94%) best explained the data in control rabbits.

Conclusion:

Results suggest that the primary site of craniosynostosis in craniosynostotic rabbits is most likely the synostosed suture. Other cranial vault anomalies are most likely secondary compensatory changes. Results of the present study may provide insight regarding the causal pathway of craniosynostosis.