bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure, dynamics, and mechanism of the lead-dependent ribozyme
Authors: Qi Xin , Xia Tianbing 
Published: July 2011

AbstractLeadzyme is a small catalytic RNA that was identified by in vitro selection for Pb2+-dependent cleavage from a tRNA library. Leadzyme employs a unique two-step Pb2+-specific mechanism to cleave within its active site. NMR and crystal structures of the active site revealed different folding patterns, but neither features the in-line alignment for attack by the 2′-OH nucleophilic group. These experimentally determined structures most likely represent ground states and are catalytically inactive. There are significant dynamics of the active site and the motif samples multiple conformations at the ground states. Various metal ion binding sites have been identified, including one that may be occupied by a catalytic Pb2+. Based on functional group analysis, a computational model of the transition state has been proposed. This model features a unique base triple that is consistent with sequence and functional group requirements for catalysis. This structure is likely only populated transiently, but imposing appropriate conformational constraints may significantly stabilize this state thereby promoting catalysis. Other ions may inhibit the cleavage by competing for the Pb2+ binding site, or by stabilizing the ground state thereby suppressing its transition to the catalytically active conformation. Some rare earth ions can enhance the reaction via an unknown mechanism. Because of its unique chemistry and dynamic behavior, leadzyme can continue to serve as an excellent model system for teaching us RNA biology and chemistry.
Bernard Palissy (1510–1590) and the French geologists: a critical reappraisal concerning the founding naturalist and his rustic ceramics
Authors: Plaziat Jean-Claude 
Published: July 2011

Abstract
Bernard Palissy benefited from two centuries (mid-18th - mid-20th c.) of a striking reputation – only partly justified – as a precursor of the European geologists and as a prolific producer of a new ceramic ware. During the last decades that appreciation was revealed to be overrated. His scientific and technological fame were respectively founded on misreadings by 18th c. rediscoverers (Jussieu, Réaumur, Fontenelle) and on erroneous attributions to a so-called “rustic Palissy’s ware style” of most of the pieces of China with animals in full relief referred to Palissy. The attributions to the Palissy’s workshop of pieces including fossil shell casts, by 19th c. romantic ceramic collectors, was confirmed by Alexandre Brongniart [1854], the pioneer decipherer, along with G. Cuvier, of the geology of the Paris basin, who identified Lutetian fossil shells. Munier-Chalmas [in Dupuy, 1894], noting that Palissy did not accept that inland fossils could belong to any marine assemblages, did not understand that this misinterpretation contradicts the current fame of Palissy as the discoverer of marine transgressions.
Modern geologists, following F. Ellenberger [1988], the first to point out this contradiction, undertook the rehabilitation of the true geological message of Palissy as a pluridisciplinary precursor in nature processes elucidation, at least equal to Leonardo da Vinci in accuracy. This contribution seeks also to solve the last major point of misunderstanding, which resulted in the mingling of the rare true rustic wares designed and produced in Palissy’s workshop at Saintes (according to the shells and vertebrates casts), with the more famous and numerous chinas, different in style, especially those with Tertiary fossil shells cast from nature, probably conceived more than a century after the rustiques figulines of Palissy, in a workshop set up in the northernmost Ile de France and not copied from them. The highest established merits of Palissy are acknowledged, that finally place him ahead of the world geologists.
Mechanical properties and surface characterization of translucent composite wire following topical fluoride treatment
Authors: Hammad Shaza M. , Al-Wakeel Essam E. , Gad El-Sayed 
Published: July 2011

AbstractObjective:To determine the effects of a fluoride prophylactic agent on the mechanical properties and surface quality of a preformed round translucent composite archwire while comparing it with nickel-titanium (Ni-Ti) and multistranded stainless steel wires.Materials and Methods:The wires were immersed in an acidulated phosphate fluoride solution (APF) or in distilled water (control) for 1.5 hours at 37°C. Flexural modulus of elasticity (E) and yield strength (YS) of the wires were measured using a three-point bending test in a universal testing machine. The springback ratio (YS/E) was calculated for each wire. The influence of fluoride treatment on properties of the wires was statistically analyzed using Student's t-test at α  =  .05. Surface changes were observed with a scanning electron microscope.Results:Fluoride treatment produced a statistically significant reduction in E, YS, and YS/E of the composite wire (P &lt; .05). In addition, a significant decrease in E of Ni-Ti wire was found after exposure to fluoride, upon comparison with distilled water control treatment. On the other hand, no significant effect of fluoride treatment was found on YS and YS/E of Ni-Ti wire and on studied properties of the multistranded stainless steel wire (P &gt; .05). Corrosive changes in surface topography were observed after exposure to the fluoride agent and were more pronounced with the composite wire.Conclusions:These results suggest that using a topical fluoride agent with translucent composite wire could decrease the mechanical properties and might damage the surface of the wire, potentially contributing to prolonged orthodontic treatment.
A comparative evaluation of lingual retainer failure bonded with or without liquid resin
Authors: Bazargani Farhan , Jacobson Sven , Lennartsson Bertil 
Published: July 2011

Abstract

Objective:
To prospectively evaluate and compare the effect of liquid resin on lingual retainer failure after a 2-year follow-up.

Materials and Methods:
Fifty-two patients (26 males, 26 females) with a mean age of 18.3 ± 1.3 years at follow-up, were randomized into two groups: the resin group and the nonresin group. The lingual retainers in the resin group were bonded to the enamel surfaces with two-step bonding resin, Optibond FL, and Tetric EvoFlow. The nonresin group followed the same procedure of bonding retainers but without applying the Optibond FL. Retainer failure, calculus accumulation, and discoloration of composite pads adjacent to the retainers during the 2-year observation period were registered, compared, and statistically analyzed with a Fisher's exact test and chi-square test.

Results:
In the resin group, the incidence of retainer failure was 4% and occurred at the composite-wire interface; in the nonresin group, the incidence was 27% and occurred at the enamel-composite interface. The difference between the groups was statistically significant (P  =  .049). The incidences of calculus accumulation and discoloration adjacent to the composite pads were 27% and 69% (P  =  .003 and P &lt; .001) higher in the nonresin group, respectively.

Conclusion:
Application of resin in bonding of lingual retainers appears to reduce the incidence of retainer failure as well as the incidence of calculus accumulation and discoloration adjacent to the composite pads.
Diagnosis of presumed acute ischemic stroke and associated seizure management in a Congo African grey parrot
Authors: Beaufrère Hugues , Nevarez Javier , Gaschen Lorrie , Ryan Kirk , Schnellbacher Rodney , Tully Thomas 
Published: July 2011

Abstract
Case Description—A 14-year-old Congo African grey parrot (Psittacus erithacus erithacus) was evaluated for an acute onset of falling off of its perch and tonic-clonic movements.
Clinical Findings—Clinical signs were consistent with partial seizures. Findings on whole-body radiography, CBC, and plasma biochemical analysis were unremarkable. Plasma magnesium, ionized calcium, and bile acids concentrations were within reference limits. A magnetic resonance imaging (MRI) examination of the head revealed the presence of a focal hyperintensity at the central to left side of the optic chiasm and a hyperintense focus in the right side of the midbrain area in T2-weighted and FLAIR pulse sequence images. These findings were most consistent with an acute ischemic stroke with 2 brain infarcts.
Treatment and Outcome—Seizures were initially managed with potassium bromide and phenobarbital administration. On the basis of poor results and difficulties to reach therapeutic blood concentrations, the treatment plan was changed to levetiracetam and zonisamide administration. Blood concentrations were monitored for both drugs, and the frequency of seizures substantially decreased thereafter. A follow-up MRI examination 2 months later revealed resolution of the hyperintense signals. During the 20-month follow-up period, subsequent clusters of seizures were managed by adjusting levetiracetam and zonisamide dosages and adding clonazepam and gabapentin administration to the treatment plan. Regression of intraparenchymal hyperintense lesions and improvement of clinical signs made a diagnosis of acute ischemic stroke most likely.
Clinical Relevance—Findings for this Congo African grey parrot indicated that an antemortem diagnosis of an acute ischemic stroke followed by long-term seizure management may be possible in affected psittacines.
Relationship of in vitro minimum inhibitory concentrations of tilmicosin against Mannheimia haemolytica and Pasteurella multocida and in vivo tilmicosin treatment outcome among calves with signs of bovine respiratory disease
Authors: McClary David G. , Loneragan Guy H. , Shryock Thomas R. , Carter Brandon L. , Guthrie Carl A. , Corbin Marilyn J. , Mechor Gerald D. 
Published: July 2011

Abstract
Objective—To determine associations between in vitro minimum inhibitory concentrations (MICs) of tilmicosin against Mannheimia haemolytica and Pasteurella multocida and in vivo tilmicosin treatment outcome among calves with clinical signs of bovine respiratory disease (BRD).
Design—Observational, retrospective, cohort study.
Animals—976 feeder calves with clinical signs of BRD enrolled in 16 randomized clinical trials.
Procedures—Records of clinical trials from October 26, 1996, to November 15, 2004, were searched to identify calves with BRD from which a single isolate of M haemolytica or P multocida was identified via culture of deep nasal swab samples prior to treatment with tilmicosin (10 mg/kg [4.5 mg/lb], SC) and for which MICs of tilmicosin against the isolate were determined. The MICs of tilmicosin against recovered isolates and response to tilmicosin treatment were evaluated.
Results—Tilmicosin resistance among M haemolytica and P multocida isolates was uncommon (6/745 [0.8%] and 16/231 [6.9%], respectively). Treatment outcome, defined as success or failure after tilmicosin treatment, did not vary with the MIC of tilmicosin against recovered isolates. The proportion of treatment failures attributed to M haemolytica isolates categorized as resistant (MIC of tilmicosin, ≥ 32 μg/mL) or not susceptible (MIC of tilmicosin, ≥ 16 μg/mL), was 0.2% and 0.5%, respectively.
Conclusions and Clinical Relevance—Recovery of tilmicosin-resistant M haemolytica or P multocida isolates was rare, and no association was detected between MIC of tilmicosin and treatment response.
Evaluation of the sedative and cardiovascular effects of intramuscular administration of dexmedetomidine with and without concurrent atropine administration in dogs
Authors: Congdon Jonathan M. , Marquez Megan , Niyom Sirirat , Boscan Pedro 
Published: July 2011

Abstract
Objective—To evaluate degree of sedation and cardiovascular, respiratory, acid-base excess, and electrolyte variables in response to IM administration of dexmedetomidine or dexmedetomidine with atropine.
Design—Randomized crossover study.
Animals—5 healthy 1- to 2-year-old sexually intact male Treeing Walker Coonhounds.
Procedures—Dogs were instrumented with catheters placed in the dorsal pedal artery and lateral saphenous vein. All dogs received dexmedetomidine (10 μg/kg [4.5 μg/lb], IM) or dexmedetomidine with atropine (0.02 mg/kg [0.009 mg/lb], IM). Variables were measured at baseline (time 0) and 5, 15, 30, and 60 minutes after drug administration.
Results—In all dogs, lithium dilution cardiac output decreased from a mean ± SD baseline value of 5.07 ± 1.0 L/min to 2.1 ± 0.9 L/min. Cardiac output was not different between dexmedetomidine group dogs and dexmedetomidine-atropine group dogs. Mean arterial pressure increased from baseline in both groups but was significantly higher in dexmedetomidine-atropine group dogs, compared with dexmedetomidine group dogs. Heart rate in dexmedetomidine group dogs decreased from 110 ± 14.2 beats/min to 49.4 ± 10.4 beats/min by 15 minutes. No differences were seen in blood gas values, electrolyte concentration, or hemoglobin values over time or between groups. Arrhythmias were detected in dexmedetomidine-atropine group dogs and included atrioventricular block, ventricular premature contractions, and ventricular bigeminy.
Conclusions and Clinical Relevance—Administration of atropine at 0.02 mg/kg, IM, with dexmedetomidine at 10 μg/kg, IM, resulted in an increase in mean arterial blood pressure and heart rate; deleterious cardiac arrhythmias were also observed. Use of atropine with dexmedetomidine is not recommended in dogs.
Preventing cerebrospinal fluid leak following transection of a tight filum terminale
Authors: Chern Joshua J. , Tubbs R. Shane , Patel Akash J. , Gordon Amber S. , Bandt S. Kathleen , Smyth Matthew D. , Jea Andrew , Oakes W. Jerry 
Published: July 2011

Object
Tethered cord release for a tight filum terminale is a common pediatric operation associated with low morbidity and mortality rates. While almost all would agree that keeping patients lying flat after the operation will prevent a CSF leak, the optimal period of doing so has not been determined. In this study, the authors examined whether a longer length of stay in the hospital for the sole purpose of maintaining patients flat correlates with a decreased rate of CSF leakage.

Methods
Intraoperative and postoperative data were retrospectively collected in 222 cases of simple tethered cord release at 3 large children's hospitals. Risk factors for postoperative CSF leakage were identified.

Results
Thirty-eight patients were maintained lying flat for 24 hours, 86 for 48 hours, and 98 for 72 hours at the individual surgeon's discretion. A CSF leak occurred in 13 patients (5.9%) and pseudomeningocele developed in 9 patients (4.1%). In the univariate analysis, operating time, use of the microscope, use of dural sealant, and duration of remaining flat after surgery failed to correlate with the occurrence of complications.

Conclusions
A longer hospital stay for maintaining patients flat after a simple tethered cord release appears not to prevent CSF leakage. However, a larger patient cohort will be needed to detect small differences in complication rates.
Safety and utility of supplemental depth electrodes for localizing the ictal onset zone in pediatric neocortical epilepsy
Authors: Kim Hyunmi , Lee Catherine , Knowlton Robert , Rozzelle Curtis , Blount Jeffrey P. 
Published: July 2011

Object
Depth electrodes provide a better sampling of sulci and regions of cortex that lie tangential to the plane of subdural electrodes. The aim of this study was to evaluate the utility of supplemental depth electrodes in the surgical treatment of pediatric patients with neocortical epilepsy.

Methods
Cases involving 12 consecutive pediatric patients (mean age [SD] 10.9 ± 4.4 years) were reviewed. Focal resective surgery (in 9 cases) or functional hemispherectomy (in 3 cases) was performed after intracranial monitoring. The mean total number of electrodes was 118 ± 29; the mean numbers of grid, strip, and depth electrodes were 95 ± 27, 10 ± 6, and 13 ± 5, respectively The most common pathological condition was focal cortical dysplasia.

Results
In 4 cases, depth electrodes demonstrated the ictal onset zone in an area not easily accessible by grids or strips (in the basal temporal region in 3 cases and the upper opercular region in 1 case). In 3 of these 4 cases, the ictal onset zone was defined exclusively by the depth electrodes. In each of these 3 cases, the surface electrodes (on grids or strips) demonstrated early propagation but not ictal onset. In 9 cases, the depth electrodes also demonstrated the early propagation zone. The information about the ictal onset zone and the early propagation zone helped to provide additional information that affected the extent (in 7 cases) or depth (in 3 cases) of the resection. The proportion of the electrodes involved in resection relative to the total number of implanted electrodes was low (mean ± SD, 0.26 ± 0.09). Nine patients (75.0%) became seizure free (Engel class IA outcome) after surgery (mean duration of follow-up 25.7 ± 4.29 months). There were no surgical complications related to intracranial electroencephalography monitoring.

Conclusions
Most patients (75.0%) became seizure free after extensive monitoring and more limited resection of seizure-onset regions. Supplemental depth electrodes contribute to improved outcome by providing information about the ictal onset zone that is not accessible by grid or strip electrodes in some cases. The supplemental depth electrodes conferred an extra dimension of depth to the analysis, which allowed for successful outcome with more limited resection.
Giant syringobulbia associated with cerebellopontine angle arachnoid cyst and hydrocephalus
Authors: Muroi Ai , Syms Nigel Peter , Oi Shizuo 
Published: July 2011

The aim in reporting this case was to discuss the pathophysiology and treatment issues in an infant with a giant syringobulbia associated with a right cerebellopontine angle (CPA) arachnoid cyst causing noncommunicating hydrocephalus. This 7-month-old infant presented to the hospital with a history of delayed milestones and an abnormal increase in head circumference. Magnetic resonance images and CT scans of the brain showed a large CSF cavity involving the entire brainstem and a right CPA arachnoid cyst causing obstruction of the fourth ventricle and dilation of the lateral and third ventricles. Cerebrospinal fluid diversion was performed by direct communication from the syringobulbia cavity to the left lateral ventricle and from the left lateral ventricle through another ventricular catheter; external ventricular drainage was performed temporarily for 5 days. Communication between the syrinx and arachnoid cyst was confirmed. Clinically, there was a reduction in head circumference, and serial MR imaging of the brain showed a decrease in the size of the syrinx cavity and the ventricle along with opening of the normal CSF pathways. The postoperative course was uneventful, and no further intervention was necessary. On follow-up of the child at 3 years, his developmental milestones were normal.
Surgical intervention for this condition is mandatory. The appropriate type of surgery should be performed on the basis of the pathophysiology of the developing syringobulbia.
Pediatric cerebellar pilomyxoid-spectrum astrocytomas
Authors: Forbes Jonathan A. , Mobley Bret C. , O'Lynnger Thomas M. , Cooper Calvin M. , Ghiassi Mahan , Hanif Rimal , Pearson Matthew M. 
Published: July 2011

Object
Pediatric cerebellar astrocytomas with pilomyxoid features include classic pilomyxoid astrocytomas (PMAs) and intermediate pilomyxoid tumors (IPTs). Since the original description of PMA in 1999, most reports in the literature have described PMAs arising from the hypothalamic/chiasmatic region. To the authors' knowledge, PMAs arising from the posterior fossa have not been discussed in the neurosurgical literature. Intermediate pilomyxoid tumors, or tumors with pathological features of both pilocytic astrocytoma (PA) and PMA, have only recently been described. In this article, the authors present 2 cases that fall within the spectrum of pediatric cerebellar PMA—including a classic PMA and an intermediate pilomyxoid tumor. The authors compare the radiological presentation, surgical results, and postoperative course to findings in a cohort of 15 patients with cerebellar PAs.

Methods
Between 2003 and 2010, 2 patients with pilomyxoid-spectrum astrocytomas underwent treatment at Vanderbilt Children's Hospital. One was a 22-month-old girl who presented with progressive gait disturbance and falls. The other was a 4-year-old girl who presented with ataxia and generalized weakness. In a retrospective review of pediatric cerebellar neoplasms resected by the senior author during this period, these tumors comprised 4% of cerebellar neoplasms and approximately 10% of cerebellar glial neoplasms.

Results
Both patients were treated with midline suboccipital craniotomy for resection. In both cases, tumor invasion anteriorly into the brainstem prevented gross-total resection. the patient in Case 1 was placed on chemotherapy following pathological diagnosis and later developed definitive evidence of leptomeningeal dissemination (LD) 3 years after the operation. The patient in Case 2 was placed on chemotherapy after exhibiting progressive evidence of local recurrence (findings were negative for LD) 12 months following resection.

Conclusions
Pediatric patients with cerebellar pilomyxoid-spectrum astrocytomas appear to suffer higher rates of local recurrence and LD than pediatric patients with cerebellar PAs.
Treatment for delayed presentation of sagittal synostosis: challenges pertaining to occult intracranial hypertension
Authors: Seruya Mitchel , Oh Albert K. , Boyajian Michael J. , Posnick Jeffrey C. , Keating Robert F. 
Published: July 2011

Object
Patients with delayed presentation of isolated sagittal synostosis (ISS) pose unique surgical challenges. Intracranial hypertension can be missed in the absence of overt findings. Here, an algorithm is presented for the elucidation of intracranial hypertension and approaches to surgical treatment during calvarial reconstruction.

Methods
Patients with delayed presentation (age > 15 months) of ISS between 1997 and 2009 were identified. Symptoms, signs, and radiological evidence of intracranial hypertension were noted. Intraoperative management included calvarial reconstruction in conjunction with ventriculostomy for intracranial pressure (ICP) monitoring and CSF drainage in the setting of suspected intracranial hypertension.

Results
Seventeen patients underwent calvarial reconstruction for delayed presentation of ISS. The mean surgical age was 40.5 months (16.2–82.9 months), and the average follow-up was 34.2 months (0.6–92.2 months). Eleven patients with subtle findings of intracranial hypertension underwent ICP monitoring during calvarial reconstruction. The mean opening ICP was 23.5 cm H2O (16.5–29.5 cm H2O), and the mean closing ICP was 7.0 cm H2O (3.5–17.0 cm H2O). Nine (81.8%) of 11 monitored patients demonstrated intracranial hypertension (ICP ≥ 20 cm H2O); the other 2 had borderline increased ICP. Perioperative morbidity was 5.9%, with 1 patient medically treated for transient, new-onset intracranial hypertension. The postoperative Whitaker category was I in 94.1% of patients, II in 5.9%, and III/IV in 0%. There were no reoperations or deaths.

Conclusions
In this consecutive series, 11 of 17 patients with delayed presentation of ISS underwent ICP monitoring during calvarial reconstruction as a result of subtle clinical findings of intracranial hypertension. Nine (81.8%) of 11 monitored patients demonstrated intracranial hypertension. Calvarial reshaping along with ICP monitoring and CSF drainage facilitated reconstruction and resulted in good outcomes and the resolution of intracranial hypertension.