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PubMed1992

A fractographic investigation of PMMA bone cement focusing on the relationship between porosity reduction and increased fatigue life.

Fracture surfaces of both monotonic and fatigue loaded bone cement samples were examined to investigate the fractographic characteristics of PMMA. Classic cleavage step river patterns were observed on all monotonically loaded samples, running downstream in the direction of crack propagation. All fatigue cracks initiated at internal pores and the direction of crack propagation of many cracks was discernible. Porosity, pore size, and pore size distribution were found to affect the crack initiation and fatigue behavior of bone cement. Statistical analysis revealed a strong negative correlation between two-dimensional porosity present on the fracture surfaces and the cycles to failure. The fractographic observations of these fatigue samples elucidate one reason why porosity reduction by centrifugation or vacuum mixing increases the fatigue life of PMMA bone cement.

Biocompatible Materials↗
PubMed1997

Phosphorylation of steroidogenic acute regulatory protein (StAR) modulates its steroidogenic activity.

Steroidogenic acute regulatory protein (StAR) plays a critical role in steroid hormone synthesis. StAR is thought to increase the delivery of cholesterol to the inner mitochondrial membrane where P450scc resides. Tropic hormones acting through the intermediacy of cAMP rapidly increase pregnenolone synthesis, and this rapid steroidogenic response is believed to be due to StAR's action. The StAR protein contains two consensus sequences for phosphorylation catalyzed by protein kinase A that are conserved across all species in which the amino acid sequence of the StAR protein has been determined. We demonstrated that human StAR expressed in COS-1 cells exists in at least four species detectable by two-dimensional gel electrophoresis followed by Western blotting. The two more acidic species disappeared after treatment of the cell extracts with alkaline phosphatase. 32P was incorporated into StAR protein immunoprecipitated from COS-1 cell extracts, and a 10-min treatment with 8-bromo-cAMP increased 32P incorporation into the StAR preprotein. StAR protein generated by in vitro transcription/translation was phosphorylated by the protein kinase A catalytic subunit in the presence of [gamma-32P]ATP. Mutation of potential sites for protein kinase A-mediated phosphorylation at serine 57 and serine 195 to alanines, individually, reduced 32P incorporation from labeled ATP into StAR preprotein produced by in vitro transcription/translation when incubated with protein kinase A catalytic subunit. 32P labeling of StAR protein expressed in COS-1 cells was also reduced when serine 57 or serine 195 were mutated to alanines. A double mutant in which both serine 57 and serine 195 were changed to alanines displayed markedly reduced 32P incorporation. To determine the functional significance of StAR phosphorylation, we tested the steroidogenic activity of the wild-type StAR and mutated StAR proteins in COS-1 cells expressing the human cholesterol side chain cleavage enzyme system. Mutation of the conserved protein kinase A phosphorylation site at serine 57 had no effect on pregnenolone synthesis. However, mutation of the serine residue at 195 resulted in an approximately 50% reduction in pregnenolone production. The S195A mutant construct did not yield the more acidic species of StAR detected in two-dimensional Western blots, indicating that the mutation affected the ability of the protein to be post-translationally modified. Mutation of the corresponding serine residues in murine StAR (Ser56 and Ser194) to alanines yielded results that were similar to those obtained with human StAR; the S56A mutant displayed a modest reduction in steroidogenic activity, whereas the S194A mutant had approximately 40% of the activity of murine wild-type StAR. In contrast to the human S195A mutation, conversion of serine 195 to an aspartic acid residue had no effect on steroidogenic activity, consistent with the idea that a negative charge at this site modulates StAR function. Our observations suggest that phosphorylation of serine 194/195 increases the biological activity of StAR and that this post- or co-translational event accounts, in part, for the immediate effects of cAMP on steroid production.

Amino Acid Sequence↗
PubMed1990

The nuclear matrix from cells of different origin. Evidence for a common set of matrix proteins.

We compared the protein composition of the nuclear matrix isolated from several murine embryonal carcinoma cells and mature tissues by two-dimensional gel electrophoresis. Two nuclear matrix fractions were investigated: the "peripheral" nuclear matrix (matrix proteins that remain insoluble after reduction), and the "internal" nuclear matrix (matrix proteins released by reduction). The two subfractions have completely different protein compositions. Although numerous differences in nuclear matrix protein composition among different cell types were observed, a limited set of polypeptides common to all mouse cell types was identified. A majority of these common proteins was also present in cells from other mammalian species (i.e. rat and human). For this set of proteins, we coin the term "minimal matrix." As expected, lamin B, known to be expressed throughout differentiation, is part of the common set of peripheral nuclear matrix proteins. Lamins A and C are not because these proteins were absent from undifferentiated embryonal carcinoma cells. Since these common nuclear matrix proteins occur in all mammalian nuclear matrices analyzed so far, it is likely that they have a basic role in nuclear organization and function.

Animals↗
PubMed1981

Inhibition of tumor growth, vascularization, and collagenolysis in the rabbit cornea by medroxyprogesterone.

Medroxyprogesterone, dexamethasone, or cortisone, locally applied in sustained release polymer to rabbit V2 carcinoma implanted in the rabbit cornea, blocked neovascularization and three-dimensional growth of the tumor. These hormones similarly prevented the vascular proliferative response to implants in the rabbit cornea of mouse B-16 melanoma and also the response to implants of polymer containing tumor extract with angiogenesis activity. The inhibitory responses were accompanied by considerable reduction in collagenolytic activity released into culture medium by explants of the two tumors and of the corneal region containing angiogenic hepatoma extract. Morphologic studies revealed extensive three-dimensional disruption of the compact laminated collagenous structure of the cornea by untreated V2 carcinoma. In the presence of hormone the tumor grew slowly as a noninvasive two-dimensional plaque limited to the narrow region of the insertion pocket in the cornea, with no obvious disturbance of structure elsewhere. Cortisone was much les effective than medroxyprogesterone or dexamethasone. Testosterone and estradiol had no effect on the three measured properties. The data suggest that local hormonal interference with neovascularization, collagenase production, and tumor growth can prevent neoplastic invasion and destruction of a dense collagenous connective tissue.

Animals↗
PubMed2002

Interatrial septum pacing guided by three-dimensional intracardiac echocardiography.

OBJECTIVES: Currently, the interatrial septum (IAS) pacing site is indirectly selected by fluoroscopy and P-wave analysis. The aim of the present study was to develop a novel approach for IAS pacing using intracardiac echocardiography (ICE). BACKGROUND: Interatrial septum pacing may be beneficial for the prevention of paroxysmal atrial fibrillation. METHODS: Cross-sectional images are acquired during a pull-back of the ICE transducer from the superior vena cava into the inferior vena cava by an electrocardiogram- and respiration-gated technique. Both atria are then reconstructed using three-dimensional (3D) imaging. Using an "en face" view of the IAS, the desired pacing site is selected. Following lead placement and electrical testing, another 3D reconstruction is performed to verify the final lead position. RESULTS: Twelve patients were included in this study. The IAS pacing was achieved in all patients including six suprafossal (SF) and six infrafossal (IF) lead locations all confirmed by 3D imaging. The mean duration times of atrial lead implantation and fluoroscopy were 70 +/- 48.9 min and 23.7 +/- 20.6 min, respectively. The IAS pacing resulted in a significant reduction of the P-wave duration as compared to sinus rhythm (98.9 +/- 19.3 ms vs. 141.3 +/- 8.6 ms; p < 0.002). The SF pacing showed a greater reduction of the P-wave duration than IF pacing (59.4 +/- 6.6 ms vs. 30.2 +/- 13.6 ms; p < 0.004). CONCLUSIONS: Three-dimensional ICE is a feasible tool for guiding IAS pacing.

Adult↗
PubMed2006

Intracranial volume changes in craniosynostotic rabbits: effects of age and surgical correction.

BACKGROUND: The premature fusion of one or more cranial sutures, termed craniosynostosis, alters normal brain growth patterns and results in compensatory changes in the cranial vault. The authors previously reported that bilateral coronal suture fusion resulted in a reduction in intracranial volume in a rabbit model of nonsyndromic, familial coronal suture synostosis. METHODS: The current follow-up study involved collecting cross-sectional three-dimensional computed tomographic head scans from 142 rabbits (70 normal, 44 with uncorrected synostosis, and 28 synostosed rabbits with coronal suturectomy) at 0, 10, 25, 42, 84, and 126 days of age. Intracranial contents were reconstructed, and indirect intracranial volume was calculated. RESULTS: Results revealed a significant (p < 0.05) postsynostotic reduction of intracranial volume (23 percent) by 25 days of age in rabbits with uncorrected craniosynostosis compared with normal controls, which continued through 84 days of age. Also, rabbits with surgically released synostosis, using a simple strip suturectomy, showed significantly (p < 0.05) greater intracranial volume at 25 days of age compared with unoperated synostosed rabbits. However, no changes in intracranial volume were noted between 42 and 84 days of age in rabbits with surgically released synostosis, at which point their intracranial volume was 30 percent less than that in normal control rabbits. CONCLUSIONS: These data suggest that in rabbits with uncorrected craniosynostosis, compensatory changes in the neurocranium were not capable of compensating for the loss of sutures as growth sites. The results also showed that that surgical release of the synostosed suture improved intracranial volume in the short term (25 to 42 days) but failed to change it in the long term (42 to 84 days), possibly because of rapid resynostosis of the suturectomy site. This study suggests that surgical release of the suture fusion site alone may not be adequate to allow for normal intracranial volume growth in synostotic rabbits. For this reason, it may be efficacious to design and develop adjunct protein and gene therapies to prevent resynostosis and improve postoperative intracranial volume in craniosynostotic individuals.

Age Factors↗
PubMed2006

[Functional outcome after corrective osteotomy of the distal radius].

BACKGROUND: Malunited fractures of the distal radius frequently show disabling and painful reductions in active range of motion (AROM) of the wrist and forearm with reduced grip strength. Shortening and three-dimensional torsion of the distal radius occur with relative ulnar lengthening. Corrective osteotomy of the distal radius is indicated in these conditions. METHODS: We examined 24 of 30 patients after corrective osteotomy with respect to AROM, grip strength, DASH, and pain perception (visual analogue scale). The mean age of the population was 49 years (18-69 years), and the mean follow-up period was 22 months (6-63 months). RESULTS: Preoperative extension/flexion was 65 degrees , postoperative 92 degrees (p<0.05). Forearm rotation improved from 129 degrees preoperative to 160 degrees postoperative (p<0.01). The DASH score could be reduced from 40 (n=9) to 18 (n=24). Grip strength increased from 17 kg to 27 kg postoperative (p<0.01). Radioulnar inclination increased from 15 degrees preoperative to 24 degrees postoperative (p<0.05). Relative ulnar lengthening could be minimized from 4.3 mm to 0.7 mm (p<0.05). CONCLUSION: Data show that reconstruction of the distal radius improves grip strength and range of motion significantly with simultaneous reduction of pain perception and DASH scores.

Adolescent↗
PubMed1979

Sulphydryl oxidase: oxidation of sulphydryl groups and the formation of three-dimensional structure in proteins.

Sulphydryl oxidase, an enzyme isolated from milk, catalyses the de novo synthesis of disulphide bonds. Thiol groups in amino acids or their derivatives, peptides, and proteins are oxidized; molecular oxygen serves as the electron acceptor and undergoes a two-electron reduction to hydrogen peroxide. Michaelis constants vary considerably amongst various substrates; glutathione is a particularly good substrate. Inhibition studies and oxidation of 1,3-diphenylisobenzofuran suggest a mechanism involving an electron transfer to singlet O2 forming an enzyme-bound hydroperoxy group. Evidence for a direct interaction of the enzyme with horseradish peroxidase was also obtained. Although protein-folding appears to be thermodynamically favoured, rates of spontaneous acquisition of functional three-dimensional structures in disulphide-containing proteins have appeared disturbingly slow. In the presence of sulphydryl oxidase, functional structure is rapidly acquired by both reductively unfolded ribonuclease A and reductively denatured immobilized chymotrypsinogen A as judged by restoration of native fluorescence characteristics and biological activity. Preliminary data suggest that unlike thiol:protein-disulphide oxidoreductase, protein-disulphide isomerase, or GSSG/GSH redox systems, sulphydryl oxidase does not permit a 'reshuffling' of disulphide bonds.

Animals↗
PubMed2006

An accurate simulation model of anteriorly displaced TMJ discs with and without reduction.

Internal derangement of the temporomandibular joint (TMJ) is defined as an abnormal positional relationship of the disc relative to the mandibular condyle and the glenoid fossa. Among others, the anterior disc displacement is the most common disorder, however its origin and consequences are still unclear. Several finite element simulations of the TMJ have been developed, but none of them has reported dynamic simulations of the disc as a three-dimensional, fiber-reinforced biphasic material under finite deformations, during the opening movement of a pathologic joint affected of an anterior displacement of the disc with and without reduction, using a realistic geometry of the ligaments in the joint. The aim of the work presented here was to compare the stress distribution in the healthy joint and in two pathologic situations, one joint affected of an anterior disc displacement with reduction (ADDWR) and one without reduction (ADDWOR) during an opening movement of the mouth. It was found that, while in the healthy disc the highest compressive stresses were located in the intermediate zone, in the pathologic joints the maximum compressive stresses were located in the posterior band both in the ADDWOR case and in the ADDWR before the reduction. Moreover, although the final stress distribution in the ADDWR was similar to that in the healthy case, the collateral ligaments supported higher stresses, a fact that could lead to degeneration of these components and subsequently to the total anterior displacement of the disc. Finally, the results suggest that an anterior displacement of the disc would lead to higher compressive and tangential stresses in the posterior band of the disc than in the healthy one, and as a consequence, to possible perforations in that zone of the disc which would modify its geometry if no treatment is applied.

Bite Force↗
PubMed2002

[Experimental study of pseudo-stenosis artifact on three-dimensional DSA].

Rotational three-dimensional digital subtraction angiography (3D-DSA) is very useful for interventional neuroradiology, especially in the endovascular therapy of cerebral aneurysms. However, pseudo-stenosis artifact on the vessel, which runs vertically to the rotational axis, was observed clinically. In this study, this artifact was confirmed in an experiment with 4.5-millimeter diameter vessel phantoms. The attenuation of the phantom at each degree of exposure (44 directions) was measured on the workstation (DSA pixel value). DSA pixel values were plotted from data of 10, 20, 30, 40, and 50 millimeter lengths, respectively. The saturated DSA pixel value of tangent projection on phantoms of 30 millimeters or more in length was observed. This phenomenon induces pseudo-stenosis artifact on 3D-DSA. The maximum reduction in the diameter of the phantom was 27.4% on the length of 50 millimeters. We confirmed that the two-dimensional data vertical to the rotational axis were inaccurate when a straight-coursed, long, segmented vessel was present. Under this special condition, vessels on 3D-DSA were displayed as smaller than their actual diameter.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Three-dimensional computed tomography and polysomnography findings after extended uvulopalatal flap surgery for obstructive sleep apnea.

OBJECTIVES: Using both sleep physiological parameters and image data to evaluate the efficacy of extended uvulopalatal flap (EUPF) surgery in the treatment of obstructive sleep apnea (OSA). MATERIAL AND METHODS: Fifty patients with OSA underwent EUPF that consisted of bilateral tonsillectomy, dissection and removal of the submucosal adipose tissue of the soft palate and supratonsillar areas, and imbrications and repositioning of the denuded uvulopalatal flap. Polysomnography (PSG) and 3-dimensional computed tomography (3-D CT) data were obtained at baseline and 6 months postoperatively. Good response to surgery was defined as a reduction of the respiratory disturbance index (RDI) to less than 20 events/h and a greater than 50% reduction of the baseline RDI. RESULTS: Forty-two patients (84%) achieved good results. The RDI and minimal O2 saturation improved significantly (P<.0001) after EUPF. The postoperative 3-D CT evaluation showed a significant increase in the retropalatal space (P<.0001). The preoperative lateral diameter of retropalatal space was predictive of the change of RDI (R2=0.15, P=.05). The effect of increased retropalatal space (r=0.59, P=.0415) was significant in patients with baseline RDI ranged from 31 to 60 events/h. CONCLUSIONS: With special emphasis on the removal of palatal fat, EUPF appeared to be effective in the reduction of sleep apnea in selected patients. 3-D CT proved that this technique was effective in widening the upper airway by relieving the retropalatal obstruction.

Adult↗
PubMed1999

Influence of the ratio between radial artery inner diameter and sheath outer diameter on radial artery flow after transradial coronary intervention.

To test the feasibility of using guiding catheters equal to or greater than 7 Fr in transradial coronary intervention (TRI), we measured the inner diameter of the radial artery (RA) and its flow using two-dimensional ultrasound and Doppler examinations before and after TRI in 250 Japanese patients. The incidence of severe flow reduction of the RA after TRI was 6.8% on average (7.2%, 4.7%, and 8.3% in patients with 6, 7, and 8 Fr sheaths used, respectively), which increased from 4.0% to 13.0% (P=0.0113) if the ratio of the RA inner diameter/sheath outer diameter was less than 1.0. The frequency of this ratio (> or = 1.0) for 7 and 8 Fr sheaths was 71.5% and 44.9% in male patients and 40.3 and 24.0% in female patients, respectively. We conclude that the use of guiding catheters equal to or greater than 7 Fr in the radial artery is feasible in selected patients.

Adult↗
PubMed1989

Three-dimensional morphological study of the pancreatic microvasculature in caerulein-induced experimental pancreatitis.

A morphological study of the pancreatic microvasculature in experimental pancreatitis was performed in dogs, using three-dimensional scanning electron microscopy vascular casting and transmission electron microscopy. Animals with pancreatitis were characterized by a marked reduction in the number of capillaries outlined by the cast and by distortion of those that were outlined, with irregularity of the capillary lumen, abruptly terminating capillary buds and leakage of the cast material through the capillary membrane. The study provides convincing morphological evidence that one of the earliest changes in acute pancreatitis is distortion of the capillary circulation.

Acute Disease↗
PubMed1986

Analysis of protein incorporation of radioactive isotopes in the Chinese hamster ovary cell cycle by electronic sorting and gel microelectrophoresis.

The patterns of [3H]-leucine and [32P]-phosphate incorporation of proteins extracted with varying molarities of sodium chloride were analyzed from nuclei physically sorted from six fluorescence windows after propidium iodine staining of the G0 + G1 and G2 + M phases of the Chinese hamster ovary (CHO) cell cycle. Eight hundred nanograms of protein were used in each electrophoretic analysis obtained from 200,000 nuclei, a portion of the sample, from each window. Autoradiography was performed in a two-dimensional polyacrylamide gel ultra-microelectrophoresis apparatus (UMEA) designed and fabricated in this laboratory. There was a net reduction and/or loss of [3H]-leucine- and [32P]-phosphate-labeled protein regions from the autoradiographs occurring primarily in the G2 + M phase. Two phosphorylated proteins that were stage specific were observed in partitions of the G2 + M phase. The use of isolated proteins and the coelectrophoresis of these markers demonstrated the similarity in mobility of a number of proteins seen in the autoradiographs of proteins extracted with high and low salt molarities and implied they are synonymous. Coelectrophoresis indicated that a substantial number of high molecular weight proteins that decreased or disappeared at late stages of G2 + M and early mitosis were composed, in part, of nucleolar proteins.

Animals↗
PubMed2003

Vitamin E prevents oxidation of antiapoptotic proteins in neuronal cells.

Oxidative damage to neuronal proteins appears to be central to the toxicity associated with a number of neuropathologies, including Alzheimer's disease. We have examined this by using oxidative stress to induce apoptosis in a mouse hippocampal neuronal cell line (HT-22). Oxidatively modified proteins were measured by high-resolution two-dimensional gel electrophoresis coupled with oxidation-specific immunostains. Under these conditions the oxidatively stressed cells undergo apoptosis, and specific proteins are oxidized. The three proteins that appeared to be most susceptible to oxidation were identified by mass spectrometry. Those oxidized proteins are heat shock protein 60 and vimentin, both believed to function as antiapoptotic proteins, and a third protein with sequence homology to hemoglobin alpha-chain. When the cells were pretreated with vitamin E, these proteins were not oxidized and the cells did not undergo apoptosis.

Animals↗
PubMed2005

Improvement of two-dimensional gel electrophoresis proteome maps of the haloarchaeon Haloferax volcanii.

Proteins of haloarchaea are remarkably unstable in low-ionic-strength solvents and tend to aggregate under standard two-dimensional (2-D) gel electrophoresis conditions, causing strong horizontal streaking. We have developed a new approach to generate 2-D maps of halophilic proteins which included washing cells with 1.5 M Tris-HCl buffer. In addition, proteins were precipitated with acetone, solubilized with urea and thiourea in the presence of the sulfobetaine detergent 3-[(3-cholamidopropyl)dimethylamino]-1-propanesulfonate (CHAPS), reduced with tributylphosphine (TBP), and separated with microrange strips of immobilized pH gradients (pH 3.9-5.1). This combination enabled the construction of highly reproducible 2-D maps of Haloferax volcanii proteins.

Acetone↗
PubMed2006

Pseudomonas putida KT2440 responds specifically to chlorophenoxy herbicides and their initial metabolites.

Pseudomonas putida KT2440 is often used as a model to investigate toxicity mechanisms and adaptation to hazardous chemicals in bacteria. The objective of this paper was to test the impact of the chlorophenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-(2,4-dichlorophenoxy)propanoic acid (DCPP) and their metabolites 2,4-dichlorophenol (DCP) and 3,5-dichlorocatechol (DCC), on protein expression patterns and physiological parameters. Both approaches showed that DCC has a different mode of action and induces different responses than DCPP, 2,4-D and DCP. DCC was the most toxic compound and was active as an uncoupler of oxidative phosphorylation. It repressed the synthesis of ferric uptake regulator (Fur)-dependent proteins, e.g. fumarase C and L-ornithine N5-oxygenase, which are involved in oxidative stress response and iron uptake. DCPP, 2,4-D and DCP were less toxic than DCC. They disturbed oxidative phosphorylation to a lesser extent by a yet unknown mechanism. Furthermore, they repressed enzymes of energy-consuming biosynthetic pathways and induced membrane transporters for organic substrates. A TolC homologue component of multidrug resistance transporters was found to be induced, which is probably involved in the removal of lipophilic compounds from membranes.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2006

Comparative proteomic approaches for the isolation of proteins interacting with thioredoxin.

Thioredoxin (TRX) is a small multifunctional protein with a disulfide active site involved in redox regulation. To gain insight into the numerous proteins able to interact with thioredoxin in Arabidopsis thaliana, we have compared three different proteomic procedures. In the two first approaches targets present in a mixture of soluble leaf proteins were reduced by the cytosolic TRX h3, then the new thiols were labeled either with radioactive iodoacetamide allowing specific detection (first method) or with a biotinylated thiol-specific compound allowing selective retention on an avidin column (second method). The third method involved a chromatography on a mutated TRX h3 column, which is able to covalently trap potential targets. All together, the three approaches enabled us to propose 73 proteins as being TRX-linked, and involved in various processes. Methods 1 and 3 were not only efficient with respectively 47 and 41 potential targets, but also complementary as only 26% of the targets were identified by both procedures. The second method with only 12 proteins was less efficient. However, this approach, as well as the first one when coupled with differential labeling of the cysteine residues, could be more informative about the cysteines involved in the thiol-disulfide interchange.

Arabidopsis↗