Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Yield stability”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66Linked to original sources
PubMed1995

The cyclosporin A-binding immunophilin CyP-40 and the FK506-binding immunophilin hsp56 bind to a common site on hsp90 and exist in independent cytosolic heterocomplexes with the untransformed glucocorticoid receptor.

We have recently shown that hsp56, the FK506-binding immunophilin component of both the heat shock protein (hsp90.hsp70.hsp56) heterocomplex and the untransformed glucocorticoid receptor heterocomplex, is bound directly to hsp90 (Czar, M. J., Owens-Grillo, J. K., Dittmar, K. D., Hutchison, K. A., Zacharek, A. M., Leach, K. L., Deibel, M. R., and Pratt, W. B. (1994) J. Biol. Chem. 269, 11155-11161). In this work, we show that both untransformed glucocorticoid receptor and hsp90 heterocomplexes contain CyP-40, a 40-kDa immunophilin of the cyclosporin A-binding class. CyP-40 is present in both native glucocorticoid receptor heterocomplexes and receptor heterocomplexes reconstituted with rabbit reticulocyte lysate, and the presence of CyP-40 in the receptor heterocomplex is stabilized by molybdate. Immunoadsorption of hsp90 from cell lysate yields coimmunoadsorption of both hsp56 and CyP-40, showing that both immunophilins are in native heterocomplex with hsp90. However, immunoadsorption of hsp56 does not yield coimmunoadsorption of CyP-40; thus, the two immunophilins do not exist in the same heterocomplex with hsp90. Both purified CyP-40 and hsp56 bind directly to purified hsp90, and excess CyP-40 blocks the binding of hsp56, consistent with the presence of a common immunophilin binding site on hsp90. Our data also suggest that there are at least two types of untransformed glucocorticoid receptor-hsp90 heterocomplexes, one that contains hsp56 and another that contains CyP-40. The role played by the immunophilins in steroid receptor action is unknown, but it is clear that the peptidylprolyl isomerase activity of immunophilins is not required for glucocorticoid receptor-hsp90 heterocomplex assembly and proper folding of the hormone binding domain by the hsp90-associated protein folding system of reticulocyte lysate.

Animals↗
PubMed2005

Bioluminescence resonance energy transfer reveals ligand-induced conformational changes in CXCR4 homo- and heterodimers.

Homo- and heterodimerization have emerged as prominent features of G-protein-coupled receptors with possible impact on the regulation of their activity. Using a sensitive bioluminescence resonance energy transfer system, we investigated the formation of CXCR4 and CCR2 chemokine receptor dimers. We found that both receptors exist as constitutive homo- and heterodimers and that ligands induce conformational changes within the pre-formed dimers without promoting receptor dimer formation or disassembly. Ligands with different intrinsic efficacies yielded distinct bioluminescence resonance energy transfer modulations, indicating the stabilization of distinct receptor conformations. We also found that peptides derived from the transmembrane domains of CXCR4 inhibited activation of this receptor by blocking the ligand-induced conformational transitions of the dimer. Taken together, our data support a model in which chemokine receptor homo- and heterodimers form spontaneously and respond to ligand binding as units that undergo conformational changes involving both protomers even when only one of the two ligand binding sites is occupied.

Bacterial Proteins↗
PubMed1978

Labeling of monodisperse polystyrene microspheres with tightly bound 51Cr.

Monodisperse radioactive polystyrene latex microspheres have been prepared by attachment of chromium-51 to latex spheres. Labeling was by emulsion polymerization of chromium acetylacetonate dissolved in styrene monomer using commercially available microspheres. This was accomplished with two successive polymerization steps: radiation excitation and radical polymerization initiated with potassium persulfate. After attachment of the label the particle suspension was purified by repeated centrifugation wash cycles to remove labile radioactivity. Results indicate a radioactive binding yield of greater than 80% to the particles. The stability of the label was tested in in vivo and in vitro leaching studies. In these tests, the activity leaching rate was estimated to be less than 0.2% per day.

Chromium Radioisotopes↗
PubMed1993

Radiolysis of DNA studied by HPL-gel chromatography.

Radiolytic loss of highly polymerized calf thymus DNA was measured by HPL-gel chromatography. Irradiation of DNA in 10(-2) mol dm-3 sodium phosphate under N2 and air caused the same loss. Under N2O this loss was doubled showing that the reactions of OH radicals mainly lead to strand breakage. The stability of the double helix is decisive for the yield of double strand breaks. In this work the radiation-induced degradation was altered by different sodium phosphate concentration, by substituting phosphate for perchlorate and by changing the temperature in the radiolysis of DNA under air. A decrease of the strength of non-covalent bonds in DNA always leads to an increase of degradation of DNA. Radiosensitivity of DNA is higher at pH 7 than at pH 9 or 5.

Air↗
PubMed1999

The effect of DNA replication mutations on CAG tract stability in yeast.

CAG repeat tracts are unstable in yeast, leading to frequent contractions and infrequent expansions in repeat tract length. To compare CAG repeats to other simple repeats and palindromic sequences, we examined the effect of DNA replication mutations, including alleles of pol alpha, pol delta, pol epsilon, and PCNA (proliferating cell nuclear antigen), on tract stability. Among the polymerase mutations, the pol delta mutation (pol3-14) destabilizes tracts with either CAG or CTG as the lagging strand template. One pol alpha mutation, pol1-1, destabilizes the orientation with CAG as the lagging strand template, but it has little effect on the CTG orientation. In contrast, the pol1-17 mutation has no effect on either orientation. Similarly, mutations in the proofreading functions of pol delta and pol epsilon, as well as a temperature-sensitive pol epsilon mutation, pol2-18, have no effect on tract stability. Three PCNA mutations, pol30-52, pol30-79, and pol30-90, all have drastic effects on tract stability. Of the three, pol30-52 is unique in yielding small tract changes that are indicative of an impairment in mismatch repair. These results show that while CAG repeats are destabilized by many of the same mutations that destabilize other simple repeats, they also have some behaviors that are suggestive of their potential to form hairpin structures.

DNA Polymerase I↗
PubMed1995

Characterization of alternative amino acid substitutions at arginine 830 of the androgen receptor that cause complete androgen insensitivity in three families.

We have studied two different missense mutations at arginine-830 in exon 7 of the human androgen receptor (hAR) gene that cause complete androgen insensitivity (CAIS) in three families. These substitutions result from point mutations at nucleotide 2489: a G-->T transversion causes Arg830Leu and a G-->A transition causes Arg830Gln. Genital skin fibroblasts of the patients have negligible androgen-binding capacity. The mutations were recreated in an hAR cDNA expression vector that was transiently transfected into COS-1 cells. Both mutant androgen receptors have increased dissociation rate constants and apparent equilibrium rate constants when measured with 5 alpha-dihydrotestosterone or the synthetic, nonmetabolizable androgens, mibolerone or methyltrienolone. The mutant androgen-binding activities share a distinctive thermal misbehavior. At 37 degrees C R830Q and R830L are about 40% and 10% of normal, respectively. At 22 degrees C both mutants gain androgen binding while the normal decreases by 20%; for R830Q the augmented value approaches 60% of the normal. During prolonged 18 h incubation at 37 degrees C, androgen binding of the normal AR is stable while that of both mutants decreases by at least 85%. Both mutants have a very reduced ability to transactivate a cotransfected androgen-responsive reporter gene, but R830Q is better than R830L. We conclude that arginine-830 is important for A-R complex stability, and that its replacement by glutamine or leucine yields distinctive functional aberrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2001

A pilot study of defenses in adults with personality disorders entering psychotherapy.

This study examined defensive functioning in adults entering open-ended dynamic psychotherapy and determined whether defenses predict retention at 1 year. Beginning at about the fifth session, 14 adults with personality and or depressive disorders entering open-ended dynamic psychotherapy had five therapy sessions audiotaped. The sessions were rated according to the Defense Mechanism Rating Scales, quantitative method. Interrater reliability of overall defensive functioning (ODF) and the number of defenses used per session were intraclass R = .85 and .83, respectively, whereas that of seven defense levels yielded a median of .625 (range .52 to .80). Stability of ODF across the five sessions was intraclass R = .48. The 11 subjects with personality disorders (PDs) used predominantly lower immature (49.3%) and neurotic (40.8%) level defenses. Subjects with borderline PD had significantly lower ODF than those with other PD types. Higher ODF was associated with remaining in treatment at 1 year, although this was confounded with a higher frequency of weekly sessions. Quantitative assessment of defenses demonstrated fair to excellent reliability and indicated that in the short term approximately half of defensive functioning reflects a stable repertoire, whereas the remaining variation may be due to occasion and error. PDs and especially BPD are characterized by a predominance of lower defenses. Higher defensive functioning was associated with twice-weekly sessions and retention in therapy at 1 year. In therapy, adjusting technique to the patient's defenses may improve retention and outcome.

Adolescent↗
PubMed1989

Titanium wire internal fixation for stabilization of injury of the cervical spine: clinical results and postoperative magnetic resonance imaging of the spinal cord.

Nine patients with dislocation of the cervical spinal with posterior ligamentous damage were treated with posterior internal fixation using a twisted pair of 22-gauge titanium wires and iliac crest bone fusion. Fixation using the titanium wire was compared with fixation using stainless steel wire for differences in surgical insertion, long term stability of bony fusion, and postoperative magnetic resonance imaging (MRI) artifacts near the implanted wire. MRI of the cervical spine is valuable for diagnosing the acute and chronic consequences of traumatic cervical spinal injury by providing anatomic evaluation of both the spinal cord and the supporting bony/ligamentous structures in the neck. Because MRI is an accurate and sensitive noninvasive test, it is especially useful for the long-term serial assessment of the region near the cervical dislocation site to detect the sequelae of spinal cord injury, including syrinx, arachnoid cyst, cord tethering, and persistent mechanical impingement on the spinal cord or spinal roots. Previous attempts at our institution to obtain useful MRI scans of the cervical region adjacent to stainless steel wires after posterior wire fixation have failed due to marked imaging artifacts from the ferromagnetic properties of these wires. Our substitution of biocompatible titanium wire (Titanium 6 A1-4V ELI alloy, Specialty Steel and Forge, Leonia, New Jersey) for stainless steel wire produced identical immediate stabilization and ultimate bony fusion of the fracture and yielded minimal MRI artifacts overlying the immediately adjacent spinal cord and neural canal; however, the installation was technically more difficult, because of the titanium wire's greater stiffness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2005

Minimally invasive total knee arthroplasty: the results justify its use.

UNLABELLED: A mini-midvastus capsular incision was used in a feasibility study of 100 patients having primary total knee arthroplasty. Patients with marked limitation of motion were excluded from the study. Patients were followed up for a minimum of 2 years after surgery. The exposure yielded excellent results clinically and radiographically with restoration of stability and motion. The length of the skin incision varied from 8 to 15 cm with a mean of 10.5 cm. Using the limited exposure did not result in implant malpositioning. The surgical approach was not applicable in patients with a BMI > 40 or in those patients with a severe fixed valgus deformity. LEVEL OF EVIDENCE: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed2001

Natural 2',5'-phosphodiester bonds found at the ligation sites of peach latent mosaic viroid.

Peach latent mosaic viroid (PLMVd) is a circular RNA pathogen that replicates in a DNA-independent fashion via a rolling circle mechanism. PLMVd has been shown to self-ligate in vitro primarily via the formation of 2',5'-phosphodiester bonds; however, in vivo the occurrence and necessity of this nonenzymatic mechanism are not evident. Here, we unequivocally report the presence of 2', 5'-phosphodiester bonds at the ligation site of circular PLMVd strands isolated from infected peach leaves. These bonds serve to close the linear conformers (i.e., intermediates), yielding circular ones. Furthermore, these bonds are shown to stabilize the replicational circular templates, resulting in a significant advantage in terms of viroid viability. Although the mechanism responsible for the formation of these 2',5'-phosphodiester bonds remains to be elucidated, a hypothesis describing in vivo nonenzymatic self-ligation is proposed. Most significantly, our results clearly show that 2',5'-phosphodiester bonds are still present in nature and that they are of biological importance.

Mosaic Viruses↗
PubMed2005

Protein secretion in Lactococcus lactis : an efficient way to increase the overall heterologous protein production.

Lactococcus lactis, the model lactic acid bacterium (LAB), is a food grade and well-characterized Gram positive bacterium. It is a good candidate for heterologous protein delivery in foodstuff or in the digestive tract. L. lactis can also be used as a protein producer in fermentor. Many heterologous proteins have already been produced in L. lactis but only few reports allow comparing production yields for a given protein either produced intracellularly or secreted in the medium. Here, we review several works evaluating the influence of the localization on the production yields of several heterologous proteins produced in L. lactis. The questions of size limits, conformation, and proteolysis are addressed and discussed with regard to protein yields. These data show that i) secretion is preferable to cytoplasmic production; ii) secretion enhancement (by signal peptide and propeptide optimization) results in increased production yield; iii) protein conformation rather than protein size can impair secretion and thus alter production yields; and iv) fusion of a stable protein can stabilize labile proteins. The role of intracellular proteolysis on heterologous cytoplasmic proteins and precursors is discussed. The new challenges now are the development of food grade systems and the identification and optimization of host factors affecting heterologous protein production not only in L. lactis, but also in other LAB species.

Journal Article↗
PubMed2006

Luminescent quantum dots: a very attractive and promising tool in biomedicine.

Luminescent semiconductor nanocrystals, also known as quantum dots (QDs), are generally composed of II-VI and III-V elements. Due to their quantum confinement of charge carriers in tiny spaces, QDs show some unique and fascinating optical properties, and are characterized as sharp and symmetrical emission spectra, high quantum yields, broad absorption spectra, good chemical and photo-stability and size dependent emission wavelength tunability. Recently, QDs have been successfully used as new fluorescent tags in many biological and biomedical fields, and will become a new promising tool in biomedical studies, clinical diagnostics, drug delivery and photodynamic therapy. In this review, firstly, the methodology of QDs preparation was introduced, which included organic synthesis, aqueous synthesis and microwave assisted aqueous synthesis. Secondly, some procedures for the QDs bio-conjugation with biomarkers were described. And then, some key applications of QDs were summarized, which mainly covered biomedical imaging, immunoassay, DNA hybridization, and photodynamic therapy. Finally, future prospects were discussed.

Animals↗
PubMed1998

Stability of some hypothesized psychological determinants of fertility control.

Ratings of Self-Status International, a scale designed to measure behavioral and attitudinal correlates of fertility control, was administered to 95 undergraduates on two occasions four weeks apart to estimate the stability of the 12 measured factors. The test-retest correlation of scores from the two times was .58. Ten of the 12 factor scores had estimates of stability ranging between .48 and .69, but two factors yielded coefficients of .23 (p < .05) and .32 (p < .01) only, indicating need for revision or reformulation.

Adult↗
PubMed1992

Intermolecular cystine-bonding of murine interleukin 2 indicates that ligand dimerization is important for the formation of the high-affinity receptor complex.

Interleukin 2 is thought to be active as a monomeric protein. As the nonessential Cys-140 of murine interleukin 2 (mIL2) is located in the hydrophobic interface of the amphiphilic F domain it was successfully used to stabilize hydrophobic amino acid contacts between two mIL2 cores yielding biologically active cystine-bonded dimeric mIL2. (3H) thymidine incorporation assays with intermolecular cystine-bonded or monomeric mIL2 revealed almost identical median effective concentrations (EC50) and high-affinity dissociation constants (Kdh), respectively. Comparative binding and internalization assays suggest that one cystine-bonded dimeric or two monomeric mIL2 molecules bind to the high-affinity receptor complex. Furthermore, DSS concentration-dependent crosslinking studies using monomeric mIL2 revealed four membrane-derived protein-complexes with apparent molecular weights of about 70 kDa, 85 kDa, 95 kDa and 100 kDa, respectively, showing that both mIL2 receptor chains may be crosslinked to a monomeric or dimeric ligand molecule, respectively. We therefore propose that dimerization of murine interleukin 2 occurring either in solution at concentrations above the low-affinity dissociation constant or at the low-affinity receptor is important for regulation of high-affinity complex formation and signal transduction.

Amino Acid Sequence↗
PubMed2000

A novel immunoadsorbent for rheumatoid arthritis therapy--preparation and efficacy evaluation.

AIM: To develop a novel immunoadsorbent for rheumatoid arthritis (RA) therapy. METHODS: A RA immunoadsorbent was developed by binding heat-aggregated human IgG(HAHIgG) to porous agar gel beads. Its adsorption capacity for rheumatoid factors (RFs), storage stability and blood compatibility were evaluated. RESULTS: The coupling yield of HAHIgG on the carrier was 6.0 mg/g wet gel. Saturation adsorption capacity of the adsorbent for IgMRF, IgGRF and IgARF were 3400, 2240 and 2400 IU/g, respectively. The adsorbent can be stored at 4 degrees C for three months without significant variance in its activity. Its fine permeability and hemocompatibility were demonstrated by extracorporeal hemoperfusion on rabbits. CONCLUSION: HAHIgG/agar gel is a safe and effective immunoadsorbent for RA therapy, its potential clinical use is promising in the future.

Agar↗
PubMed2005

Biomechanical analysis of a newly designed bioabsorbable anterior cervical plate. Invited submission from the joint section meeting on disorders of the spine and peripheral nerves, March 2005.

OBJECT: The authors present a biomechanical analysis of a newly designed bioabsorbable anterior cervical plate (ACP) for the treatment of one-level cervical degenerative disc disease. They studied anterior cervical discectomy and fusion (ACDF) in a human cadaveric model, comparing the stability of the cervical spine after placement of the bioabsorbable fusion plate, a bioabsorbable mesh, and a more traditional metallic ACP. METHODS: Seven human cadaveric specimens underwent a C6-7 fibular graft-assisted ACDF placement. A one-level resorbable ACP was then placed and secured with bioabsorbable screws. Flexibility testing was performed on both intact and instrumented specimens using a servohydraulic system to create flexion-extension, lateral bending, and axial rotation motions. After data analysis, three parameters were calculated: angular range of motion, lax zone, and stiff zone. The results were compared with those obtained in a previous study of a resorbable fusion mesh and with those acquired using metallic fusion ACPs. For all parameters studied, the resorbable plate consistently conferred greater stability than the resorbable mesh. Moreover, it offered comparable stability with that of metallic fusion ACPs. CONCLUSIONS: Bioabsorbable plates provide better stability than resorbable mesh. Although the results of this study do not necessarily indicate that a resorbable plate confers equivalent stability to a metal plate, the resorbable ACP certainly yielded better results than the resorbable mesh. Bioabsorbable fusion ACPs should therefore be considered as alternatives to metal plates when a graft containment device is required.

Absorbable Implants↗
PubMed1999

The nonresilient hybrid removable prosthesis: treatment of choice for the atrophic maxilla.

This article presents the ments of the nonresilient hybrid removable prosthesis, which is the treatment of choice for the atrophic maxilla. The technique described may be adapted to yield a predictable outcome that provides functional and biomechanical stability that are superior to a resilient over-denture, along with a cosmetic and phonetic result that often proves superior to that of the fixed prosthesis.

Alveolar Bone Loss↗
PubMed1992

Supracondylar fractures of the humerus in children.

We undertook a retrospective study of 39 children with displaced supracondylar fractures treated by delayed closed reduction with fluoroscopic guidance. After 3-5 days of side-arm traction, swelling had usually diminished sufficiently to allow the elbow to be safely hyperflexed to stabilize the fracture after elective closed reduction. This method yielded 92% good or excellent results. There were no vascular problems or Volkmann's contractures.

Casts, Surgical↗