bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microglia‐Derived Elastase Produces a Low‐Molecular‐Weight Plasminogen that Enhances Neurite Outgrowth in Rat Neocortical Explant Cultures
Authors: Nakajima Kazuyuki , Nagata Koichi , Hamanoue Makoto , Takemoto Nagisa , Kohsaka Shinichi 
Published: October 2006

AbstractIn the course of analysis of plasminogen in microglial conditioned medium (Mic‐CM), novel low‐molecular‐weight (LMW) zymogen with a molecular mass of ∼36 kDa was detected by casein‐urokinase zymography. Because this form was produced when rat native plasminogen was incubated with Mic‐CM, a specific protease in the Mic‐CM was thought to be responsible for the production of LMW plasminogen. The production of LMW plasminogen was strongly inhibited by elastase inhibitors. Furthermore, elastase (pancreatic or leukocyte) was also found to produce LMW zymogen from native plasminogen. These results indicate that LMW plasminogen is produced through limited proteolysis by an elastase‐like protease in Mic‐CM. To determine the biochemical characteristics of LMW plasminogen, rat native plasminogen was cleaved by pancreatic elastase, and the fragments (LMW plasminogen and nonzymogen fragments) were purified by several kinds of column chromatography. Amino acid sequence analysis revealed that LMW plasminogen is a carboxy‐terminal region that contains the fifth kringle domain and a protease active site, and the amino acid sequence is identical to that of LMW plasminogen produced by MicCM. On the other hand, the nonzymogen fragment was the amino‐terminal region containing four kringle domains. The effects of native plasminogen and the fragments on neurite outgrowth of rat brain explant were examined. LMW plasminogen promoted neurite outgrowth as well as did native plasminogen, whereas nonzymogen fragments did not. These results suggest that LMW plasminogen, which is produced from native plasminogen by elastase, may be a physiologically active molecule that mediates the intercellular interaction between microglia and neurons.
Involvement of Adenosine‐Sensitive Cyclic AMP‐Generating Systems in Cobalt‐Induced Epileptic Activity in the Rat
Authors: Hattori Yukio , Moriwaki Akiyoshi , Hayashi Yasushi , Hori Yasuo 
Published: October 2006

AbstractAn injection of cobalt chloride solution into the unilateral sensorimotor cortex of rats induced electrographic epileptic activity, which was followed by a peripheral motor disturbance. Brain slices were prepared from the cortical region including the injection site and from the other cortical regions of rats between 8 and 50 days after the injection. In the cortical slices, we examined cyclic AMP accumulations elicited by adenosine and its stable analogue 2‐chloroadenosine. Adenosine and 2‐chloroadenosine at their maximal dose increased cyclic AMP accumulation six‐ to 10‐fold and 10–15‐fold, respectively, and the elicitation was markedly inhibited by the adenosine antagonist 8‐phenyltheophylline. The cyclic AMP accumulation was increased in the primary epileptic region of the cortex adjacent to the injection site of cobalt chloride solution, whereas it was unchanged in the other cortical regions. The increase in cyclic AMP accumulation was observed regardless of the presence or absence of the adenosine uptake inhibitor dipyridamole, the phosphodiesterase inhibitor DL‐4‐(3‐butoxy‐4‐methoxybenzyl)‐2‐imidazolidinone, and adenosine deaminase. Such an increased accumulation of cyclic AMP in the primary epileptic cortex was detected as early as 8 days after the injection. The cyclic AMP accumulation continued to increase and reached a peak level 17–19 days after the injection, and it returned to the control levels after 40–50 days, in correspondence with the electrographic and behavioral findings. It is concluded that alterations in adenosine receptormediated generation of cyclic AMP in the primary epileptic cortex are closely associated with the central process of cobalt‐induced epilepsy. In general, the adenosine‐sensitive cyclic AMP‐generating systems may serve as a common mechanism in experimental models of epilepsy.
Plasma 5‐Hydroxyindoleacetic Acid as an Indicator of Monoamine Oxidase‐A Inhibition in Rat Brain and Peripheral Tissues
Authors: Celada Pau , Artigas Francesc 
Published: October 2006

AbstractWe have examined the changes induced by the monoamine oxidase (MAO; EC 1.4.3.4) inhibitors tranylcypromine, clorgyline, and deprenyl on MAO activity and 5‐hydroxytryptamine (serotonin, 5‐HT) and 5‐hydroxyindoleacetic acid (5‐HIAA) content in rat brain and blood (plasma and whole blood). The decreases of MAO‐A activity observed in the liver and lungs after different doses of clorgyline or tranylcypromine correlated significantly (r > 0.80 in all cases) with the decline of plasma 5‐HIAA. This was unaffected by 0.25 and 5 mg kg−1 of deprenyl, indicating that 5‐HT was deaminated exclusively in the periphery by MAO‐A. It is interesting that very potent and significant correlations (r > 0.75) were found between plasma 5‐HIAA and MAO‐A activity, 5‐HIAA and 5‐HT content in brain tissue. These results suggest that plasma 5‐HIAA can be used confidently as a peripheral indicator of the inhibition of MAO‐A in brain. This may represent a favorable alternative to the analysis of 5‐HIAA in CSF in psychiatric patients undergoing antidepressant treatment with nonspecific MAO inhibitors or with the new selective MAO‐A inhibitors.
Chronic Cocaine Administration Increases CNS Tyrosine Hydroxylase Enzyme Activity and mRNA Levels and Tryptophan Hydroxylase Enzyme Activity Levels
Authors: Vrana Sheila L. , Vrana Kent E. , Koves Timothy R. , Smith James E. , Dworkin Steven I. 
Published: October 2006

AbstractCocaine is an inhibitor of dopamine and serotonin reuptake by synaptic terminals and has potent reinforcing effects that lead to its abuse. Tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH) catalyze the rate‐limiting steps in dopamine and serotonin biosynthesis, respectively, and are the subject of dynamic regulatory mechanisms that could be sensitive to the actions of cocaine. This study assessed the effects of chronic cocaine on brain TH and TPH activities. Cocaine was administered (0.33 mg/infusion, i.v.) to rats for 7 days every 8 min for 6 h per day. This administration schedule is similar to patterns of self‐administration by rats when given ad libitum access to this dose. This chronic, response‐independent administration increased TH enzyme activity in the substantia nigra (30%) and ventral tegmental area (43%). Moreover, TH mRNA levels were also increased (45 and 50%, respectively). In contrast to the enzymatic and molecular biological changes in the cell bodies, TH activity was unchanged in the terminal fields (corpus striaturn and nucleus accumbens). Similarly, TPH activity was increased by 50% in the raphe nucleus (serotonergic cell bodies). In summary, the chronic response‐independent administration of cocaine produces increases in the expression of TH mRNA and activity in both the cell bodies of motor (nigrostriatal) and reinforcement (mesolimbic) dopamine pathways. These increases are not manifested in the terminal fields of these pathways.
Determination of Kainic Acid‐Induced Release of Nitric Oxide Using a Novel Hemoglobin Trapping Technique with Microdialysis
Authors: Balcioglu Aygul , Maher Timothy J. 
Published: October 2006

AbstractWe have demonstrated the usefulness of a novel hemoglobin‐trapping technique to quantify nitric oxide (NO) concentrations in vivo. Concentric microdialysis probes were implanted into the hippocampus of rats under urethane anesthesia and perfused with 1 μM oxyhemoglobin in artificial CSF to sequester NO in extracellular fluid. The concentration of methemoglobin was then determined spectrophotometrically. The basal level of NO in hippocampus was 2.2 ± 0.5 nM(in vitro sensitivity of the probe was 0.2 nM). Administration of 13 mg/kg, i.p., of kainic acid (KA) produced a maximal 5.3‐fold increase at 100 min in NO levels (11.8 ± 0.2 nM). This response was significantly attenuated by pretreatment with the NO synthase inhibitor N‐monomethyl‐L‐arginine (50 mg/kg, 30 min before KA). These results demonstrate that a microdialysis probe using a novel hemoglobin‐trapping technique possesses adequate sensitivity to determine the basal levels of NO and document the ability of KA to increase these levels via a NO synthase‐mediated mechanism.
Neurotoxicity of Human Amylin in Rat Primary Hippocampal Cultures: Similarity to Alzheimer's Disease Amyloid‐β Neurotoxicity
Authors: May Patrick C. , Boggs Leonard N. , Fuson Kimberly S. 
Published: October 2006

AbstractAmylin, a 37‐amino‐acid amyloidogenic peptide, bears biophysical similarities to the amyloid‐β peptide (Aβ) deposited in Alzheimer's disease. Using embryonic rat hippocampal cultures we tested whether amylin induces neurotoxicity similar to that previously observed with Aβ(1–40). Treatment with human amylin (1–37) resulted in prominent toxicity as assessed by phasecontrast microscopy and quantification of lactate dehydrogenase in the medium. Amylin‐induced neurotoxicity was morphologically similar to that induced by Aβ(1–40). In contrast, the nonamyloidogenic rat amylin showed negligible neurotoxicity despite having 95% sequence similarity to human amylin. Only full‐length human amylin was toxic; various amylin peptide fragments including amino acid residues 20–29 were nontoxic at similar concentrations. These studies suggest that unrelated amyloidogenic peptides like human amylin and Aβ can adopt a similar neurotoxic conformation in vitro. Similar conformation‐dependent neurotoxicity may drive the prominent neurite degeneration around compacted but not diffuse deposits of Aβ in Alzheimer's disease.
GCSE Art and Design: An Arena for Orthodoxy or Creative Endeavour?
Authors: Walker Keith , Parker Jane 
Published: October 2006

AbstractThis article explores the potential correlation between key aspects of the creative process and the requirements of GCSE Art and Design Specifications as determined and defined by stated assessment objectives. It considers approaches that might be employed to more effectively establish a link between pupils’ creative endeavours and their necessary evidencing of attainment in respect of these objectives. In order to illustrate and amplify this enquiry reference is made to specific examples of candidates' work that was selected by the Assessment and Qualifications Alliance (AQA) to exemplify and disseminate GCSE Art and Design standards for teachers in 2006. It concludes with a set of implications for consideration.
Use of a Synthetic Bone Substitute to Retard Molariform Tooth Drift After Maxillary Tooth Loss in Ponies
Authors: VLAMINCK LIEVEN E.M. , HUYS LUC , MAES DOMINIEK , STEENHAUT MICHEL L.M. , GASTHUYS FRANK 
Published: October 2006

Objective— To evaluate the effect of alveolar bone substitute on post‐extraction drift of maxillary cheek teeth in ponies.Study Design— In vivo longitudinal experimental study.Animals— Five ponies (5–7 years) with a healthy dentition.Methods— Both maxillary 4th premolar teeth (Triadan 08) were surgically removed. One alveolus was filled with a biocompatible non‐resorbable bone substitute (Bioplant® 24), whereas the other healed by second intention. A polyvinylsiloxane plug and spring wire isolated the bone substitute from the oral environment. Pathologic changes to dentition and adjacent soft tissue were recorded. Tooth drift was calculated after 1 and 2 years.Results— At 1 month, bone substitute material was incorporated into healthy tissue. Tooth drift was observed but differed significantly between control and treated sides at 2 years (P<.01). For both techniques, tooth drift differed significantly between years 1 and 2 (P<.001). Total drift in control arcades for year 1 was 10.69±2.12 mm and for year 2 was 9.08±0.87 mm, whereas for bone substitute arcades it was 9.90±1.60 mm for year 1 and 5.60±1.78 mm for year 2.Conclusions— Partial tooth replacement therapy after maxillary P4 extraction provided good healing in the immediate post‐surgical phase. Alveolar filling with bone substitute material significantly slowed post‐extraction tooth drift but did not stop it completely.Clinical Relevance— Important changes occur in equine dentition after maxillary cheek teeth removal. Further longer term observations are needed to fully validate study findings.
Cell Growth Characteristics and Differentiation Frequency of Adherent Equine Bone Marrow–Derived Mesenchymal Stromal Cells: Adipogenic and Osteogenic Capacity
Authors: VIDAL MARTIN A. , KILROY GAIL E. , JOHNSON JILL R. , LOPEZ MANDI J. , MOORE RUSTIN M. , GIMBLE JEFFREY M. 
Published: October 2006

Objectives—To characterize equine bone marrow (BM)‐derived mesenchymal stem cell (MSC) growth characteristics and frequency as well as their adipogenic and osteogenic differentiation potential.Study Design—In vitro experimental study.Animals—Foals (n=3, age range, 17–51 days) and young horses (n=5, age range, 9 months to 5 years).Methods—Equine MSCs were harvested and isolated from sternal BM aspirates and grown up to passage 10 to determine cell‐doubling (CD) characteristics. Limit dilution assays were performed on primary and passaged MSCs to determine the frequency of colony‐forming units with a fibroblastic phenotype (CFU‐F), and the frequency of MSC differentiation into adipocytes (CFU‐Ad) and osteoblasts (CFU‐Ob).Results—Initial MSC isolates had a lag phase with a significantly longer CD time (DT=4.9±1.6 days) compared with the average DT (1.4±0.22 days) of subsequent MSC passages. Approximately 1 in 4224±3265 of the total nucleated BM cells displayed fibroblast colony‐forming activity. Primary MSCs differentiated in response to adipogenic and osteogenic inductive conditions and maintained their differentiation potential during subsequent passages.Conclusions—The frequency, in vitro growth rate, and adipogenic and osteogenic differentiation potential of foals and young adult horses are similar to those documented for BM MSCs of other mammalian species.Clinical Relevance—The results have direct relevance to the use of BM as a potential source of adult stem cells for tissue engineering applications in equine veterinary medicine.
Comparison of Radiography and Computed Tomography to Evaluate Metacarpo/Metatarsophalangeal Joint Pathology of Paired Limbs of Thoroughbred Racehorses with Severe Condylar Fracture
Authors: MORGAN JOSEPH W. , SANTSCHI ELIZABETH M. , ZEKAS LISA J. , SCOLLAY‐WARD MARY C. , MARKEL MARK D. , RADTKE CATHERINE L. , SAMPLE SUSANNAH J. , KEULER NICHOLAS S. , MUIR PETER 
Published: October 2006

Objective—To compare the orthogonal radiographic (OR) and computed tomographic (CT) appearance of paired Thoroughbred racehorse limbs with severe condylar fracture.Study Design—In vitro study.Sample Population—Cadaveric paired limbs with severe condylar fracture (n=11 horses).Methods—Four standard radiographic and multiple transverse CT images were obtained of the fractured and contralateral limbs centering on the metacarpo/metatarsophalangeal (fetlock) joints. Radiographs and CT images were graded by 4 raters, and interobserver agreement was calculated. Imaging evaluations were supplemented by fetlock joint dissection. A consensus description of actual injury and the detection accuracy of OR and CT for that injury was determined.Results—Rater agreement for OR and CT for most pathologic features was good or excellent. OR was similar to CT for the detection of condylar and diaphyseal third metacarpal and metatarsal (MC/MT3) fractures, diaphyseal fractures of the first phalanx (P1), and fracture location on the condyle. CT was superior to OR for detection of MC/MT3 proximal fissures and articular comminution, condylar small cracks and lucencies, and proximal sesamoid fractures. OR was superior to CT for detection of proximal P1 dorsal fractures. Both OR and CT were poor at detecting palmar/planter proximal P1 fractures and coalescing cracks in the subchondral bone of MC/MT3.Conclusions—CT is better than OR for detection of pathology in limbs with condylar fractures, but does not detect every pathologic feature.Clinical Relevance—CT provides superior information of pathology in Thoroughbred racehorses with condylar fractures.
Computer‐Assisted Surgery for Screw Insertion into the Distal Sesamoid Bone in Horses: An In Vitro Study
Authors: GYGAX DIEGO , LISCHER CHRISTOPH , NITZEL DAGMAR , ROSSOL MELANIE , AUER JOERG A. 
Published: October 2006

Objective— To compare the precision of computer‐assisted surgery with a conventional technique (CV) using a special guiding device for screw insertion into the distal sesamoid bone in horses.Study Design— In vitro experimental study.Sample Population— Cadaveric forelimb specimens.Methods— Insertion of a 3.5 mm cortex screw in lag fashion along the longitudinal axis of intact (non‐fractured) distal sesamoid bones was evaluated in 2 groups (8 limbs each): CV and computer‐assisted surgery (CAS). For CV, the screw was inserted using a special guiding device and fluoroscopy, whereas for CAS, the screw was inserted using computer‐assisted navigation. The accuracy of screw placement was verified by radiography, computed tomography, and specimen dissection.Results— Surgical precision was better in CAS compared with CV.Conclusion— CAS improves the accuracy of lateromedial screw insertion, in lag fashion, into the distal sesamoid bone.Clinical Relevance— The CAS technique should be considered for improved accuracy of screw insertion in fractures of the distal sesamoid bone.
An In Vitro Biomechanical Comparison Between Prototype Tapered Shaft Cortical Bone Screws and AO Cortical Bone Screws for an Equine Metacarpal Dynamic Compression Plate Fixation of Osteotomized Equine Third Metacarpal Bones
Authors: SOD GARY A. , HUBERT JEREMY D. , MARTIN GEORGE S. , GILL MARJORIE S. 
Published: October 2006

Objectives—To compare biomechanical properties of a prototype 5.5 mm tapered shaft cortical screw (TSS) and 5.5 mm AO cortical screw for an equine third metacarpal dynamic compression plate (EM‐DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones.Study Design—Paired in vitro biomechanical testing of cadaveric equine MC3 with a mid‐diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation.Animal Population—Adult equine cadaveric MC3 bones (n=12 pairs).Methods—Twelve pairs of equine MC3 were divided into 3 groups (4 pairs each) for (1) 4‐point bending single cycle to failure testing, (2) 4‐point bending cyclic fatigue testing, and (3) torsional single cycle to failure testing. An EM‐DCP (10‐hole, 4.5 mm) was applied to the dorsal surface of each, mid‐diaphyseal osteotomized, MC3 pair. For each MC3 bone pair, 1 was randomly chosen to have the EM‐DCP secured with four 5.5 mm TSS (2 screws proximal and distal to the osteotomy; TSS construct), two 5.5 mm AO cortical screws (most proximal and distal holes in the plate) and four 4.5 mm AO cortical screws in the remaining holes. The control construct (AO construct) had four 5.5 mm AO cortical screws to secure the EM‐DCP in the 2 holes proximal and distal to the osteotomy in the contralateral bone from each pair. The remaining holes of the EM‐DCP were filled with two 5.5 mm AO cortical screws (most proximal and distal holes in the plate) and four 4.5 mm AO cortical screws. All plates and screws were applied using standard AO/ASIF techniques. Mean test variable values for each method were compared using a paired t‐test within each group. Significance was set atP<.05.Results—Mean 4‐point bending yield load, yield bending moment, bending composite rigidity, failure load and failure bending moment of the TSS construct were significantly greater (P<.00004 for yield andP<.00001 for failure loads) than those of the AO construct. Mean cycles to failure in 4‐point bending of the TSS construct was significantly greater (P<.0002) than that of the AO construct. The mean yield load and composite rigidity in torsion of the TSS construct were significantly greater (P<.0039 andP<.00003, respectively) than that of the AO construct.Conclusion—The TSS construct provides increased stability in both static overload testing and cyclic fatigue testing.Clinical Relevance—The results of this in vitro study support the conclusion that the EM‐DCP fixation using the prototype 5.5 mm TSS is biomechanically superior to the EM‐DCP fixation using 5.5 mm AO cortical screws for the stabilization of osteotomized equine MC3.
A Comparison of Laryngoplasty and Modified Partial Arytenoidectomy as Treatments for Laryngeal Hemiplegia in Exercising Horses
Authors: RADCLIFFE CATHERINE H. , WOODIE J. BRETT , HACKETT RICHARD P. , AINSWORTH DOROTHY M. , ERB HOLLIS N. , MITCHELL LISA M. , SODERHOLM L. VINCE , DUCHARME NORM G. 
Published: October 2006

Objective—To compare upper airway mechanics, arterial blood gases, and tracheal contamination in horses with induced left laryngeal hemiplegia (recurrent laryngeal neuropathy [RLN]) treated by laryngoplasty/vocal cordectomy (LPVC) or modified partial arytenoidectomy (MPA).Study Design—Repeated measures under the following conditions: Control, RLN, LPVC, and MPA.Animals—Six horses.Methods—Two trials were conducted under all conditions at 80% and 100% of maximal heart rate (HRmax). In Trial 1, arterial blood gases, tracheal and pharyngeal pressures, and laryngeal videoendoscopy were recorded. In Trial 2, upper airway pressure and airflow were determined. Tracheobronchial aspirates were performed after exercise to quantify airway contamination.Results—Compared with control, RLN significantly increased inspiratory impedance and worsened exercise‐induced hypoxemia. At 80% HRmax, LPVC restored most variables to control values. At 100% HRmax, LPVC improved all variables, but did not restore minute volume, arterial pH, and PaCO2. At 80% HRmax, MPA restored all variables except bicarbonate to control values. At 100% HRmax, MPA improved all variables, but did not statistically restore minute ventilation or bicarbonate level. Only minor differences were noted between LPVC and MPA. Both resulted in equivalent tracheal contamination.Conclusions—Airway mechanics and arterial blood gas values were not restored to normal after either LPVC or MPA in horses exercising at HRmax. This does not affect ventilation at sub‐maximal exercise, but has clinical implications at HRmax. Both procedures diminish normal laryngeal protective mechanisms.Clinical Relevance—At sub‐maximal exercise intensities both LPVC and MPA restore airway ventilation to normal. At maximal exercise the superiority of LPVC over MPA is slight.