Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polyglutamic Acid”

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 883 records · Page 49Linked to original sources
PubMed2006

Polyelectrolyte multilayer film coating and stability at the surfaces of oral prosthesis base polymers: an in vitro and in vivo study.

A new type of coating involving a layer-by-layer technique has been recently reported. This coating is composed of a polyelectrolyte multilayer film that confers specific properties on surfaces to which it is applied. Here, we studied the applicability of such a technique to the coating of oral prostheses, by first testing the construction of polyelectrolyte multilayer films on several polymers used in oral prosthesis bases, and, subsequently, by studying the stability of these coatings in vitro, in human saliva, and in vivo in a rat model. We demonstrated that the multilayered films are able to coat the surfaces of all tested polymers completely, thus increasing their wettability. We also showed that saliva does not degrade the film after 7 days in vitro and after 4 days in vivo. Taken together, our results establish that the layer-by-layer technique is suitable for the coating of oral devices.

Acrylates↗
PubMed1995

Risk of relapse in childhood acute lymphoblastic leukemia is related to RBC methotrexate and mercaptopurine metabolites during maintenance chemotherapy. Nordic Society for Pediatric Hematology and Oncology.

PURPOSE: During maintenance chemotherapy for childhood acute lymphoblastic leukemia (ALL), the cytotoxic metabolites of methotrexate (MTX polyglutamates) and mercaptopurine (6MP) (thioguanine nucleotides [6TGN]) accumulate intracellularly, including in erythrocytes (E-MTX and E-6TGN) with large interindividual variations. In the present Nordic Society for Pediatric Hematology and Oncology (NOPHO) study, the relation of E-MTX and E-6TGN to relapse risk was explored. PATIENTS AND METHODS: Two hundred ninety-seven patients with non-B-cell ALL, aged 1 to 14 years, on oral MTX and 6MP had E-MTX and E-6TGN levels measured three to 35 (median, eight) and three to 75 (median, nine) times, respectively. For each patient, a mean of all E-MTX (mE-MTX) and E-6TGN (mE-6TGN) measurements was calculated, as well as the product of mE-MTX and mE-6TGN (mE-MTX-6TGN), since MTX and 6MP may have synergistic action. RESULTS: For patients in remission, the median mE-MTX and mE-6TGN values were 4.7 nmol/mmol hemoglobin (Hgb) (range, 0.4 to 10.3) and 173 nmol/mmol Hgb (range, 58 to 846). With a median follow-up duration of 66 months for patients in remission, 64 patients relapsed. Cox regression analysis identified mE-MTX-6TGN and sex to be the most significant parameters to predict relapse (global P = .001). Factors that predicted a better prognosis were high mE-MTX 6TGN and female sex. Patients who had a mE-MTX-6TGN less than the product of the median mE-MTX and median mE-6TGN (813 [nmol/mmol Hgb]2) had a significantly poorer event-free survival (EFS) than did patients with higher values (5-year probability of EFS [pEFS5y], 0.70 v 0.86; P = .001). CONCLUSION: The pharmacokinetics of MTX and 6MP may have significant influence on the risk of relapse. The value of dose adjustments by E-MTX and E-6TGN remains to be determined.

Administration, Oral↗
PubMed2003

Characterisation of PGs1, a subunit of a protein complex co-purifying with tubulin polyglutamylase.

Polyglutamylation is a post-translational modification initially discovered on tubulin. It has been implicated in multiple microtubule functions, including neuronal differentiation, axonemal beating and stability of the centrioles, and shown to modulate the interaction between tubulin and microtubule associated proteins. The enzymes catalysing this modification are not yet known. Starting with a partially purified fraction of mouse brain tubulin polyglutamylase, monoclonal antibodies were raised and used to further purify the enzyme by immunoprecipitation. The purified enzyme complex (Mr 360x103) displayed at least three major polypeptides of 32, 50 and 80x103, present in stochiometric amounts. We show that the 32x103 subunit is encoded by the mouse gene GTRGEO22, the mutation of which has recently been implicated in multiple defects in mice, including male sterility. We demonstrate that this subunit, called PGs1, has no catalytic activity on its own, but is implicated in the localisation of the enzyme at major sites of polyglutamylation, i.e. neurones, axonemes and centrioles.

Animals↗
PubMed1999

Tubulin polyglutamylase: isozymic variants and regulation during the cell cycle in HeLa cells.

Polyglutamylation is a posttranslational modification of tubulin that is very common in neurons and ciliated or flagellated cells. It was proposed to regulate the binding of microtubule associated proteins (MAPs) and molecular motors as a function of the length of the polyglutamyl side-chain. Though much less common, this modification of tubulin also occurs in proliferating cells like HeLa cells where it is associated with centrioles and with the mitotic spindle. Recently, we partially purified tubulin polyglutamylase from mouse brain and described its enzymatic properties. In this work, we focused on tubulin polyglutamylase activity from HeLa cells. Our results support the existence of a tubulin polyglutamylase family composed of several isozymic variants specific for alpha- or beta-tubulin subunits. In the latter case, the specificity probably also concerns the different beta-tubulin isotypes. Interestingly, we found that tubulin polyglutamylase activity is regulated in a cell cycle dependent manner and peaks in G(2)-phase while the level of glutamylated tubulin peaks in mitosis. Consistent results were obtained by treating the cells with hydroxyurea, nocodazole or taxotere. In particular, in mitotic cells, tubulin polyglutamylase activity was always low while glutamylation level was high. Finally, tubulin polyglutamylase activity and the level of glutamylated tubulin appeared to be inversely related. This paradox suggests a complex regulation of both tubulin polyglutamylase and the reverse deglutamylase activity.

Animals↗
PubMed1999

Polyglutamylation and polyglycylation of alpha- and beta-tubulins during in vitro ciliated cell differentiation of human respiratory epithelial cells.

Tubulins are the major proteins within centriolar and axonemal structures. In all cell types studied so far, numerous alpha- and beta-tubulin isoforms are generated both by expression of a multigenic family and various post-translational modifications. We have developed a primary culture of human nasal epithelial cells where the ciliated cell differentiation process has been observed and quantified. We have used this system to study several properties concerning polyglutamylation and polyglycylation of tubulin. GT335, a monoclonal antibody directed against glutamylated tubulins, stained the centriole/basal bodies and the axonemes of ciliated cells, and the centrioles of non-ciliated cells. By contrast, axonemal but not centriolar tubulins were polyglycylated. Several polyglutamylated and polyglycylated tubulin isotypes were detected by two-dimensional electrophoresis, using GT335 and a specific monoclonal antibody (TAP952) directed against short polyglycyl chains. Immunoelectron microscopy experiments revealed that polyglycylation only affected axonemal tubulin. Using the same technical approach, polyglutamylation was shown to be an early event in the centriole assembly process, as gold particles were detected in fibrogranular material corresponding to the first cytoplasmic structures involved in centriologenesis. In a functional assay, GT335 and TAP952 had a dose-dependent inhibitory effect on ciliary beat frequency. TAP952 had only a weak effect while GT335 treatment led to a total arrest of beating. These results strongly suggest that in human ciliated epithelial cells, tubulin polyglycylation has only a structural role in cilia axonemes, while polyglutamylation may have a function both in centriole assembly and in cilia activity.

Cell Differentiation↗
PubMed2002

Poly-gamma-glutamate synthesis during formation of nematocyst capsules in Hydra.

Nematocysts are explosive organelles found in all Cnidaria. Explosion of nematocyst capsules is driven by the high pressure within the capsule formed by the high concentration of poly-gamma-glutamate in the capsule matrix. Poly-gamma-glutamate is a polyanion that binds cations tightly, including the fluorescent cationic dyes acridine orange and DAPI (4',6-diamidino-2-phenylindole). We have used acridine orange and DAPI staining to localize poly-gamma-glutamate within capsules and to follow the biosynthesis of poly-gamma-glutamate during capsule formation. The results indicate that poly-gamma-glutamate biosynthesis occurs late in capsule formation after invagination of the tubule and that it is accompanied by swelling of the capsule due to increasing osmotic pressure. The matrix in all four capsule types is homogeneously filled with poly-gamma-glutamate. In vivo this poly-gamma-glutamate is complexed with monovalent cations. In addition, poly-gamma-glutamate is formed within the tubule lumen of stenoteles. We argue that this poly-gamma-glutamate is required to drive the two-step explosion process in stenotele nematocysts.

Acridine Orange↗
PubMed1993

Reduction of endotoxin contamination of various crude vaccine materials by gram-negative bacteria using aminated poly(gamma-methyl L-glutamate) spherical particles.

We describe a method for the removal of endotoxins from various crude antigen solutions originating from gram-negative bacteria using aminated poly(gamma-methyl L-glutamate) (PMLG) spherical particles. The aminated PMLG adsorbents showed high affinity for various purified endotoxins at an ionic strength of mu = 0.1. The endotoxin-adsorbing capacity of the adsorbent increased with increase in the amino-group content of the adsorbent. The adsorbent (3.2 meq/g amino-group content) showed the highest affinity for endotoxin at ionic strengths ranging from mu = 0.025-0.8. The adsorption of Bordetella pertussis antigen to the adsorbent decreased with increasing amino-group content of the adsorbent at an ionic strength of mu = 0.2. The adsorption of B. bronchiseptica protein to the adsorbent increased with increasing amino-group content of the adsorbent, but decreased with increasing ionic strength. The adsorbent (3.2 meq/g of amino-group content) selectively reduced endotoxin in crude antigen solutions originating from gram-negative bacteria, B. pertussis, B. bronchiseptica and Pasteurella multocida, even at a high ionic strength (mu = 0.2-0.4) without affecting the recovery of the protective antigens.

Adsorption↗
PubMed1992

Removal of endotoxin from culture supernatant of Bordetella pertussis with aminated poly(gamma-methyl L-glutamate) spherical beads.

Attempts were made to prepare adsorbents having a high affinity for endotoxin in the culture supernatant of Bordetella pertussis. When poly(gamma-methyl L-glutamate) (PMLG) was used as a matrix and amino groups as the ligand, the highest affinity for endotoxin was attained even at a high ionic strength (mu = 0.2-0.4). PMLG beads containing amino groups of about 3.2 meq/g selectively removed endotoxin from the culture supernatant of B. pertussis without affecting the protective antigens. It was demonstrated that 1 ml of the wet adsorbent adsorbed 4.5 mg of endotoxin. The beads of PMLG derivatives, therefore, are considered to be a useful adsorbent for the removal of endotoxin from the pertussis vaccine, affecting neither filamentous hemagglutinin nor pertussis toxin.

Adsorption↗
PubMed2006

Simple improvement in freeze-tolerance of bakers' yeast with poly-gamma-glutamate.

We examined the effect of poly-gamma-glutamate (PGA) on the freeze-tolerance of four types of commercial bakers' yeast (freeze-tolerant, osmotic-tolerant, low-temperature-sensitive, and ordinary bakers' yeasts). The survival ratio of ordinary bakers' yeast cells frozen at -30 degrees C for 3 d in a medium (0.5% yeast extract, 0.5% peptone, and 2% glucose: YPD medium) was improved by adding more than 1% PGA to the medium; the survival ratio increased from about 10% to more than 70%. All PGA preparations, which differed in average molecular mass (50, 2,000, 4,000, 6,000, 8,000, and 10,000 kDa), showed a similar cryoprotecive effect on the cells. Similar results were also obtained with other types of bakers' yeast, sake yeast and beer yeast. When the four types of bakers' yeast cell were frozen at -30 degrees C for 3 d in dough supplemented with more than 1% PGA, the cells (after freezing and thawing) showed higher leavening ability than those frozen in dough without PGA, irrespective of the molecular mass of PGA. Thus, PGA appears to protect bakers' yeast from lethal freeze injury, leading to a high leavening ability after freezing and thawing. PGA did not decrease the original leavening ability of the bakers' yeast, and was not decomposed by the yeast cells. PGA suppressed the decrease in leavening ability during a prolonged fermentation time, probably because PGA adsorbed inhibitory metabolites accumulated in the dough. PGA could prove useful for improving the freeze-tolerance of bakers' yeast by its addition to dough.

Cold Temperature↗
PubMed2006

Novel poly-gamma-glutamate-processing enzyme catalyzing gamma-glutamyl DD-amidohydrolysis.

The pgdS gene product of Bacillus subtilis, PgdS, cleaves poly-gamma-glutamate (PGA) in an endo-peptidase-like fashion. However, its catalytic property remains obscure. In this study, a simple assay for the PgdS enzyme using 1-fluoro-2,4-dinitrobenzene was developed, and some characteristics of PgdS, such as optimal pH, were examined. The enzyme was strongly inhibited by a thiol-modifying reagent, suggesting that it possesses essential cysteine residue(s) in catalysis. PgdS exhibited a high affinity to PGA that consisted mainly of D-glutamate residues, but no affinity to PGA composed only of L-glutamate residues (L-PGA). The enzyme processed DL-copolymer-type PGA (DL-PGA) with an average molecular mass of 1,000 kDa to a high-molecular-mass L-glutamate-rich fragment (average 200 kDa), the L-rich PGA fragment, and low-molecular-mass fragment composed mostly of D-glutamate residues (average 5 kDa), D-fragment. To deepen our understanding of the catalytic property of the PgdS enzyme, we analyzed the structures of the N- and C-terminal regions and found that D-glutamyl residues successively lie even at both ends of the L-rich PGA fragment. Our observations indicate that PgdS is a novel endo-peptidase that specifically cleaves the gamma-amide linkage between two D-glutamate residues in PGA, i.e., gamma-glutamyl DD-amidohydrolase. The enzyme is possibly useful in the biochemical processing of B. subtilis DL-PGA.

Aminohydrolases↗
PubMed2005

Vibrational circular dichroism in general anisotropic thin solid films: measurement and theoretical approach.

In this study, the measurement of the true vibrational circular dichroism (VCD) spectrum is considered from an experimental and theoretical approach for any general anisotropic thin solid sample exhibiting linear as well as circular birefringence (LB, CB) and dichroism (LD, CD) properties. For this purpose, we have made use of a simple model alpha-helix polypeptide, namely, the poly(gamma-benzyl-L-glutamate) or PBLG, reference sample possessing a well-known VCD spectrum and giving rise to slightly oriented films by deposition onto a solid substrate. Also, we have used a different Fourier transform infrared modulation of polarization (PM-FTIR) optical setup with two-channel electronic processing in order to record the PM-VLD and PM-VCD spectra for various sample orientations in its film plane. All the corresponding general relations of the expected intensities in these experiments and the related properly designed calibration measurements were established using the Stokes-Mueller formalism; in addition, the residual birefringence of the optical setup and the transmittance anisotropy of the detector were estimated. From a comparative study of the results obtained in solution and in the solid state, we then propose a simple new experimental procedure to extract the true VCD spectrum of an oriented PBLG thin film: its consists of calculating the half-sum of two spectra recorded at theta and at theta +/- 90 degrees sample orientations. Moreover, the complete linear and circular birefringence and dichroism properties of the ordered PBLG thin film are estimated in the amide I and amide II vibrational regions. This allows us to establish for any sample orientation various theoretical simulations of the VCD spectra that agree nicely with the observed experimental results; this confirms that the measurement of LD and LB is in this case a prerequisite in simulating the true VCD spectrum of a partly oriented anisotropic sample. This validates our combined experimental and theoretical approach and opens the route to promising future vibrational CD studies on other macroscopic anisotropic thin film samples.

Algorithms↗
PubMed2006

Polarised asymmetric inheritance of accumulated protein damage in higher eukaryotes.

Disease-associated misfolded proteins or proteins damaged due to cellular stress are generally disposed via the cellular protein quality-control system. However, under saturating conditions, misfolded proteins will aggregate. In higher eukaryotes, these aggregates can be transported to accumulate in aggresomes at the microtubule organizing center. The fate of cells that contain aggresomes is currently unknown. Here we report that cells that have formed aggresomes can undergo normal mitosis. As a result, the aggregated proteins are asymmetrically distributed to one of the daughter cells, leaving the other daughter free of accumulated protein damage. Using both epithelial crypts of the small intestine of patients with a protein folding disease and Drosophila melanogaster neural precursor cells as models, we found that the inheritance of protein aggregates during mitosis occurs with a fixed polarity indicative of a mechanism to preserve the long-lived progeny.

Animals↗
PubMed2002

Differential core histone binding behavior: RNA polymerase I promoter region vs 5S rDNA positioning DNA sequences.

In order to further characterize the previously observed disruptive effect of the RNA polymerase I promoter sequence (Pol I) from Acanthamoeba castellanii on tandemly repeated 5S rDNA positioning sequences from sea urchin (Lytechinus variegatus), we compared the histone-binding ability of the isolated 199-bp Pol I promoter region to that of the 208-bp 5S rDNA and that of nucleosome core particle sequences isolated from chicken erythocytes. We found the 5S rDNA positioning sequence to be more efficient at forming nucleosomes than the RNA polymerase I promoter sequence. Nevertheless, examination of the free-DNA half-depletion points during the titrations suggested that twice as much histone had bound to the RNA polymerase I promoter sequence as to the 5S nucleosome-positioning or core particle sequences. DNA bending analysis suggested two potential DNA bending loci in the RNA polymerase I promoter, whereas only one such locus was predicted for the 5S positioning sequence. Such mixed bending signals on the RNA polymerase I promoter could favor non-nucleosomal deposition of histones on these sequences.

Acanthamoeba↗
PubMed2004

CT-2103: emerging utility and therapy for solid tumours.

CT-2103 (XYOTAX, Cell Therapeutics, Inc.) is a conjugate of paclitaxel to a polyglutamate polymer. Its macromolecular nature exploits enhanced permeability and retention in tumour tissues. This compound is stable and inactive in aqueous solution and undergoes predominantly intracellular metabolism at the site where active paclitaxel is released. Because it does not require a Cremophor EL vehicle, it can be administered by short infusion into peripheral veins. In preclinical models, compared with the same dose of unconjugated paclitaxel in Cremophor EL-ethanol, CT-2103 yields >or= 12-fold increase in area under the curve in both plasma and tumour tissue. This alteration in drug pharmacokinetics and biodistribution is attributable to the ability of macromolecules to concentrate in areas of vascular leakiness, such as tumour tissue. CT-2103 is taken up by both tumour cells and normal phagocytic cells and is transported to lysosomes, where it is released by specific proteases through enzymatic action. In syngeneic and xenogeneic tumour models, at the maximally tolerated dose, CT-2103 appears to be more active than the standard doses of paclitaxel. It has also demonstrated activity in paclitaxel-resistant tumour models. Its potential enhancement of efficacy and decrease in drug-related toxicities make this agent an attractive option for therapeutic investigation. In Phase I trials it has been relatively well-tolerated, with acceptable toxicity at doses <or= 225 mg/m(2) every 3 weeks. In combination with carboplatin the maximum tolerated dose is 235 mg/m(2) and the recommended Phase II dose 210 mg/m(2). Activity has been demonstrated in both non-small cell lung carcinoma (NSCLC) and in ovarian cancer, Phase III studies are currently testing this agent versus standard paclitaxel as maintenance therapy for first-line treatment-naive ovarian cancer. In addition, CT-2103 at a dose of 210 mg/m(2) (performance status [PS] 0 - 1) or 175 mg/m(2) (PS 2) is being compared with docetaxel (75 mg/m(2)) for the second-line treatment of NSCLC. In front-line PS 2 NSCLC patients, this agent in combination with carboplatin is undergoing comparison with paclitaxel/carboplatin; in a separate effort, single-agent CT-2103 is being compared with either gemcitabine or vinorelbine. These studies will determine whether the preclinical and early clinical promise of this agent can be realised in the clinical treatment of solid tumours.

Animals↗
PubMed2006

De novo appearance and "strain" formation of yeast prion [PSI+] are regulated by the heat-shock transcription factor.

Yeast prions are non-Mendelian genetic elements that are conferred by altered and self-propagating protein conformations. Such a protein conformation-based transmission is similar to that of PrP(Sc), the infectious protein responsible for prion diseases. Despite recent progress in understanding the molecular nature and epigenetic transmission of prions, the underlying mechanisms governing prion conformational switch and determining prion "strains" are not understood. We report here that the evolutionarily conserved heat-shock transcription factor (HSF) strongly influences yeast prion formation and strain determination. An hsf1 mutant lacking the amino-terminal activation domain inhibits the yeast prion [PSI+] formation whereas a mutant lacking the carboxyl-terminal activation domain promotes [PSI+] formation. Moreover, specific [PSI+] strains are preferentially formed in these mutants, demonstrating the importance of genetic makeup in determining de novo appearance of prion strains. Although these hsf1 mutants preferentially support the formation of certain [PSI+] strains, they are capable of receiving and faithfully propagating nonpreferable strains, suggesting that prion initiation and propagation are distinct processes requiring different cellular components. Our findings establish the importance of HSF in prion initiation and strain determination and imply a similar regulatory role of mammalian HSFs in the complex etiology of prion disease.

Alleles↗
PubMed2004

Dilemmas in management: the controversial role of chemotherapy in PS 2 advanced NSCLC and the potential role of CT-2103 (Xyotax).

Platinum-based chemotherapy improves long-term survival in patients with advanced non-small cell lung cancer (NSCLC). Meta-analyses have demonstrated an improvement in median and 1-year survival times as well as quality of life. However, these benefits are largely confined to patients with a good performance status (PS), one of the most critical determinants influencing outcome. Several clinical trials that initially included PS 2 patients ultimately discontinued their enrollment due to a high propensity of adverse reactions to treatment. The advent of more active, less toxic agents has revitalized investigator interest in treating PS 2 patients. CT-2103 is a novel paclitaxel conjugate undergoing investigation in the treatment of advanced NSCLC. The median survival for PS 2 patients treated with single-agent CT-2103 in one small trial proved similar to that reported for paclitaxel/carboplatin in NSCLC patients and was associated with an improved safety profile compared with conventional taxanes. Phase III studies comparing CT-2103 as a single agent and in combination with carboplatin to current standards of care are in progress. Unlike a well-defined population with good PS, the therapeutic index in PS 2 patients is narrower and not as clearly defined. These and other efforts will determine the optimal mode of therapy in PS 2 individuals with NSCLC.

Antineoplastic Agents↗
PubMed2006

Effects of basic fibroblast growth factor on experimental diabetic neuropathy in rats.

Basic fibroblast growth factor (bFGF) stimulates angiogenesis and induces neural cell regeneration. We investigated the effects of bFGF on diabetic neuropathy in streptozotocin-induced diabetic rats. Diabetic rats were treated with human recombinant bFGF as follows: 1) intravenous administration, 2) intramuscular injection into thigh and soleus muscles with cross-linked gelatin hydrogel (CGH), and 3) intramuscular injection with saline. Ten or 30 days later, the motor nerve conduction velocity (MNCV) of the sciatic-tibial and caudal nerves, sensitivity to mechanical stimuli, sciatic nerve blood flow (SNBF), and retinal blood flow (RBF) were measured. Delayed MNCV in the sciatic-tibial and caudal nerves, hypoalgesia, and reduced SNBF in diabetic rats were all ameliorated by intravenous administration of bFGF after 10, but not 30, days. Intramuscular injection of bFGF with CGH also improved sciatic-tibial MNCV, hypoalgesia, and SNBF after 10 and 30 days, but caudal MNCV was not improved. However, intramuscular injection of bFGF with saline had no significant effects. bFGF did not significantly alter RBF in either normal or diabetic rats. These observations suggest that bFGF could have therapeutic value for diabetic neuropathy and that CGH could play important roles as a carrier of bFGF.

Angiogenesis Inducing Agents↗