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At least 991 records · Page 55Linked to original sources
PubMed1999

Developing an injectable formula containing an oxygen-sensitive drug: a case study of danofloxacin injectable.

The purpose of this study was to assess the impact of impurities in formulation components, antioxidants, formulation pH, and processing/packaging on the extent of color change associated with oxidation of danofloxacin injectable. The methods used in this study include reversed-phase HPLC, UV-VIS spectrophotometry, atomic absorption spectroscopy, visual observation, and iodimetric titration for quantification of the antioxidant. The results from this study revealed that trace impurities from two different excipients significantly contributed to color change associated with oxidation. Polyvinyl pyrrolidone (PVP) introduced trace levels of peroxides into the solution. A second excipient also had a significant impact on stability because it introduced trace metal impurities into the product. The minimization of oxygen levels alone in the solution and headspace was not sufficient to completely eliminate the product instability. The addition of an antioxidant, monothioglycerol (MTG), resulted in a formulation less sensitive to processing variables. The impact of pH on the performance of MTG was also studied. At pH 7.5, MTG resulted in significant improvement in stability; however, at pH 6.0 it was not effective as an antioxidant. Process modifications alone may not be sufficient to prevent oxidation. Chemical approaches, such as pH control, addition of an antioxidant, and control of components should be considered first as means of enhancing stability of oxygen-sensitive solutions.

Anti-Infective Agents↗
PubMed2002

Formulation optimization and stability study of transdermal therapeutic system of nicorandil.

The aim of this research investigation was to fabricate acrylate-based stable transdermal therapeutic system (TTS) of nicorandil, which could deliver drug through transdermal route. Monolithic TTS was fabricated in pressure sensitive adhesives (PSAs)--(a) terpolymer (PSA1) of 2-ethylhexyl acrylate, methyl methacrylate, and acrylic acid, (b) copolymer (PSA2) of 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, and vinyl acetate, and (c) Eudragit E100 pressure sensitive adhesive (PSA3). To enhance the flux of nicorandil, skin permeation enhancer N-methyl-2-pyrrolidone (NMP) was investigated at different concentrations (0.05-5%) in PSAs. Fabricated TTS was evaluated for in-vitro release and skin permeation through guinea pig skin. Maximum flux of nicorandil was observed from Eudragit E100 based TTS and kept for stability study at refrigeration, 25 degrees C/30% RH and 30 degrees C/60% RH. Patches were evaluated for various physicochemical parameters. Formulation was observed to be relatively more stable at refrigeration. Shelf life of the formulation was found to be 270, 270, and 30 days at refrigeration, 25 degrees C/30% RH and 30 degrees C/60% RH conditions, respectively. Nicorandil could be successfully derived from Eudragit E100 based TTS, but attention needs to be given to improve its chemical stability in formulation.

Acrylates↗
PubMed2004

Complexation between PVP and Gantrez polymer and its effect on release and bioadhesive properties of the composite PVP/Gantrez films.

Complexation between poly(methyl vinyl ether-maleic anhydride) copolymer (Gantrez AN 169) and polyvinylpyrrolidone (PVP K-90D) in aqueous solutions were investigated using a viscometric method and Raman spectroscopy. The composite films with different weight ratios of PVP to Gantrez were prepared in the presence of N-methyl-2-pyrrolidone. The release profiles of diclofenac sodium (DS) from these films were determined and the bioadhesive properties measured. An interpolymer complex was formed through hydrogen bonding between the carbonyl groups of PVP and the hydroxyl groups of Gantrez. The formation of interpolymer hydrogen bonds reduced the interaction of the polymers with water molecules, thus resulting in a lower solubility of the complex in water and a further retarded release of DS from the composite films. The interpolymer complexation was also found to increase the bioadhesive properties of the composite films to a silicone elastomer substrate. The complexation of PVP and the Gantrez copolymer in the composite films was a critical factor affecting the release of DS from the films and the bioadhesive properties of the films.

Adhesives↗
PubMed2005

Spray drying for generation of a ternary amorphous system of celecoxib, PVP, and meglumine.

Generation of amorphous forms of a poorly soluble drug by solid dispersion techniques has been a subject of intensive research for decades. Apart from the stability of the dispersions, development of a suitable production technology is a major challenge to the successful commercialization of these products. Coprocessing of celecoxib (CEL), poly(vinyl pyrrolidone), and meglumine by spray drying resulted in an amorphous drug product that provided enhanced solubility and stability to an otherwise poorly soluble crystalline form of CEL. The spray-drying process parameters were optimized to provide an amorphous product with required characteristics. The product was stable for 3 months under the accelerated stability storage conditions. This technique can serve as a suitable means for generating a ready-to-formulate amorphous drug-additive(s) composite that can be directly filled into hard gelatin capsules.

Air Pressure↗
PubMed1974

Role of complement in induction of antibody production in vivo. Effect of cobra factor and other C3-reactive agents on thymus-dependent and thymus-independent antibody responses.

In an in vivo study in mice, suppression by the C3-cleaving protein of cobra venom (CoF), and other C3-reactive agents (zymosan, aggregated IgG, anti-C3 antibodies, and type III pneumococcal polysaccharide) of the thymus-dependent antibody responses to sheep erythrocytes, ovalbumin, and human IgG was demonstrated. The thymus-independent antibody response to polyvinyl-pyrrolidone was however unaffected by CoF. These and other published observations suggest that there may be a requirement for functional C3 in induction of thymus-dependent but not thymus-independent antibody production. A model for the role of C3 in lymphocyte cooperation is proposed based on these data analyzed in the light of existing knowledge of this process. It is postulated that fixed C3 interacting with macrophage See PDF for Structure and B-cell C3 receptors might enhance or facilitate T-dependent presentation of antigen to B cells.

Animals↗
PubMed2003

Evaluation of the performance of VIPAR polymer gels using a variety of x-ray and electron beams.

The aim of this investigation was the evaluation of the usefulness of N-vinyl pyrrolidone argon (VIPAR) polymer gel dosimetry for relative dose measurements using the majority of types and energies of radiation beams used in clinical practice. For this reason, VIPAR polymer gels were irradiated with the following beams: 6 and 23 MV photons (maximum dose: 15 Gy) and 6, 9, 12, 15, 18 and 21 MeV electrons (90% dose: 15 Gy). Using 6 MV x-rays, a linear gel dose response was verified for doses up to 20 Gy. Assuming linearity of response for the rest of the photon and electron beams used in this study, percentage depth dose measurements were derived. For all beams used and the range of relative doses studied, a satisfying agreement was observed between percentage depth dose measurements performed using the VIPAR gel-MRI method and an ion chamber, validating the assumption that a linear gel dose response holds for all photon and electron beams studied. VIPAR gels, therefore, can be used for relative dose distribution measurements using photons or electrons of any typical energy used in external radiotherapy applications. It is also demonstrated that two-dimensional dose distribution measurements through an irradiated (9 MeV electrons, 3 cm x 3 cm cone) VIPAR gel volume can be easily obtained.

Argon↗
PubMed2000

Combination of interleukin 12 and interferon alpha gene therapy induces a synergistic antitumor response against colon and renal cell carcinoma.

The antitumor effect and mechanism of action of IL-12 gene therapy combined with IFN-alpha gene therapy were investigated in tumor-bearing mice using renal and colon carcinoma models, Renca and CT26, respectively. Tumors were treated with murine IL-12 plasmid alone or in combination with IFN-alpha plasmid formulated with a polymeric interactive noncondensing (PINC) gene delivery system. Intratumoral injection of IL-12 DNA/polyvinyl pyrrolidone (PVP) alone induced rejection of 58 and 17% of Renca and CT26 tumors, respectively, whereas 25% (Renca) and 0% (CT26) rejection was observed in mice treated with IFN-alpha plasmid/PVP. Combination gene therapy of formulated plasmids, IL-12 with IFN-alpha, synergistically increased the antitumor response against Renca (100% tumor rejection) and CT26 (50%). In vivo depletion of leukocyte subsets indicated that CD8(+) T and NK cells were the primary effectors of the antitumor response induced by the combined cytokine gene therapy. Moreover, mice that rejected the primary tumors after combined treatment with IL-12 and IFN-alpha plasmid formulation developed protective immunity against a subsequent tumor challenge. Analysis of tumor-infiltrating leukocytes from mice treated with the combined IL-12 and IFN-alpha gene therapy showed upregulation of CD40 molecules on antigen-presenting cells (Mac-1(hi) cells). Finally, levels of mRNA for the chemokines IP-10 and TCA-3 were higher in tumors treated with the combination of cytokine plasmids than in tumors treated with either cytokine gene alone. These data provide evidence that IL12 gene therapy combined with IFN-alpha gene therapy synergistically induces regression of established tumors and may represent a novel therapeutic strategy for cancer treatment.

Animals↗
PubMed2003

Viability of hydroxyethyl methacrylate-methyl methacrylate-microencapsulated PC12 cells after omental pouch implantation within agarose gels.

Hydroxyethyl methacrylate-methyl methacrylate (HEMA-MMA, 75 mol% HEMA). Microcapsules containing viable PC12 cells (as an allogeneic transplant model) were implanted into omental pouches in Wistar rats. Two different capsule preparations were tested, based on differences in polymer solutions during extrusion: 10% HEMA-MMA in TEG, and 9% HEMA-MMA in TEG with 30% poly(vinyl pyrrolidone) (PVP). The omental pouch proved to be an ideal transplant site in terms of implantation, recovery, and blood vessel proximity (nutrient supply). To minimize the fibrous overgrowth and damaged capsules previously seen on implantation of individual capsules, agarose gels were used to embed the capsules before implantation. Cells proliferated within the microcapsule-agarose device during the first 7 days of implantation, but overall cell viability declined over the 3-week period, when compared with similar capsules maintained in vitro. Nonetheless, approximately 50% of the initial encapsulated cells were still viable after 3 weeks in vivo. This approach to HEMA-MMA microcapsule implantation improved cell viability and capsule integrity after 3 weeks in vivo, compared with capsules implanted without agarose.

Animals↗
PubMed2005

Internal contamination of gloves: routes and consequences.

The effect of internal glove contamination was investigated using N-methyl pyrrolidone (NMP) as a biological marker to assess systemic absorption when wearing internally contaminated gloves, and when not wearing gloves but subjected to the same challenge contaminant. The routes by which the insides of gloves become contaminated were also investigated. The area of dermal contamination was quantified using a fluorescent tracer dye and a surface monitoring fluorimeter. The main routes of internal glove contamination were found to be self-contamination, cuff entry and failed gloves. Wearing internally contaminated gloves led to higher systemic absorption than was gained from the equivalent skin contamination when not wearing gloves. Repeat wetting of fingers with aqueous NMP, when gloves were not worn, gave higher systemic absorption than the equivalent continuous exposure, probably due to the low volatility of NMP leading to increased concentration and longer residence time on the skin.

Environmental Monitoring↗
PubMed2001

High-performance liquid chromatographic determination of pyridostigmine bromide, nicotine, and their metabolites in rat plasma and urine.

This study reports on the development of a rapid and simple method for the determination of the antinerve agent drug pyridostigmine bromide (3-dimethylaminocarbonyloxy-N-methyl pyridinium bromide) (PB), its metabolite N-methyl-3-hydroxypyridinium bromide, nicotine (S-1-methyl-5-(3-pyridyl)-2-pyrrolidine), and its metabolites nornicotine (2-(3-pyridyl)pyrrolidine) and cotinine (S-1-methyl-5-(3-pyridyl)-2-pyrrolidone) in rat plasma and urine. The compounds are extracted and eluted by methanol and acetonitrile using C18 Sep-Pak cartridges and separated using high-performance liquid chromatography by a gradient of methanol, acetonitrile, and water (pH 3.2) at a flow rate of 0.8 mL/min in a period of 14 min. UV detection was at 260 nm for nicotine and its metabolites and at 280 nm for PB and its metabolite. The limits of detection ranged between 20 and 70 ng/mL, and the limits of quantitation were 50-100 ng/mL. The average percent recovery of five spiked plasma samples were 85.7 +/- 7.3%, 80.4 +/- 5.8%, 78.9 +/- 5.4%, 76.7 +/- 6.4%, and 79.7 +/- 5.7% and for urine were 85.9 +/- 5.9%, 75.5 +/- 6.9%, 82.6 +/- 7.9%, 73.6 +/- 5.9%, and 77.7 +/- 6.3% for nicotine, nornicotine, cotinine, PB, and N-methyl-3-hydroxypyridinium bromide, respectively. The calibration curves for standard solutions of the compounds of peak areas and concentration are linear for a range between 100 and 1,000 ng/mL. This method is applied in order to analyze the previously mentioned chemicals and metabolites following their oral administration in rats.

Animals↗
PubMed2001

Manufacturing DNA microarrays of high spot homogeneity and reduced background signal.

Analyses on DNA microarrays depend considerably on spot quality and a low background signal of the glass support. By using betaine as an additive to a spotting solution made of saline sodium citrate, both the binding efficiency of spotted PCR products and the homogeneity of the DNA spots is improved significantly on aminated surfaces such as glass slides coated with the widely used poly-L-lysine or aminosilane. In addition, non-specific background signal is markedly diminished. Concomitantly, during the arraying procedure, the betaine reduces evaporation from the microtitre dish wells, which hold the PCR products. Subsequent blocking of the chip surface with succinic anhydride was improved considerably in the presence of the non-polar, non-aqueous solvent 1,2-dichloroethane and the acylating catalyst N:-methylimidazole. This procedure prevents the overall background signal that occurs with the frequently applied aqueous solvent 1-methyl-2-pyrrolidone in borate buffer because of DNA that re-dissolves from spots during the blocking process, only to bind again across the entire glass surface.

DNA Probes↗
PubMed1995

Intracytoplasmic sperm injection of mouse oocytes with 5 mM Ca2+ at different intervals.

The objective of this investigation was to determine whether intracytoplasmic sperm injection (ICSI) can be performed in the mouse. Metaphase II oocytes were obtained from F1 hybrid mice (C57BL x CBA) by i.p. injections of 10 IU pregnant mare's serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) administered 48 h apart. Oocytes with cumulus oophorus were retrieved 13-14 h post HCG. Cumulus was dispersed with 0.1% hyaluronidase. Mouse spermatozoa were obtained from the cauda epididymides of males of the same strain. The spermatozoa were processed by the standard swim-up procedure. The harvested spermatozoa were then incubated for 1.5 h to allow capacitation. Healthy oocytes were injected with 3-4 pl 5 mM Ca2+, followed by one live morphologically normal spermatozoon into the cytoplasm at intervals of 0, 0.5, 1, 2 and 3 h. The proportion of 2-cell embryos that developed from oocytes injected with Ca2+ and spermatozoa ranged between 29.5 and 36.5% in all groups, with no statistical difference between treatments. Chromosomal analysis showed that two-thirds of the ICSI-derived 2-cell embryos were diploid. The proportion of parthenogenetically activated embryos in the ICSI groups was similar to that in the control group (8-10%) which was injected with Ca2+ and polyvinyl pyrrolidone only. The proportion of blastocysts that developed in culture from the ICSI-derived 2-cell embryos was of the order of 36-42%. Some blastocysts were used for cell number counts. There was a significant increase in total and inner cell mass counts of blastocysts in which the spermatozoon was injected at 2 and 3 h following Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Inactivation of pyroglutamyl aminopeptidase by N alpha-carbobenzoxy-L-pyroglutamyl chloromethyl ketone.

Pyroglutamyl aminopeptidase [pyrrolidone-carboxylate peptidase: EC 3.4.11.8] from Bacillus amyloliquefaciens was inactivated rapidly and irreversibly by N alpha-carbobenzoxy-L-pyroglutamyl chloromethyl ketone (Z-PGCK). The second-order rate constant of the inactivation was 1.1 x 10(5) M-1.s-1, a value which is comparable to that of the clostripain-TLCK reaction. The D-isomer of this chloromethyl ketone derivative was almost inert toward the enzyme under the same conditions. The inactivation reaction was prevented by the presence of a poor substrate, pyroglutamyl-valine. The PCMB-inactivated enzyme, that was reversibly reactivated by 2-mercaptoethanol, failed to react with Z-PGCK. These results suggest that this chloromethyl ketone derivative reacts as an affinity label, presumably with the active site cysteinyl residue of the enzyme, as was reported for L-pyroglutamyl chloromethyl ketone.

Affinity Labels↗
PubMed1995

Sperm pairing in the opossum increases the efficiency of sperm movement in a viscous environment.

In order to understand why sperm pairing has evolved in most American marsupials, the movement parameters of spermatozoa from Monodelphis domestica were analyzed after incubation in capacitating medium for 15 min, 2 h, and 24 h to induce a proportion of sperm pairs to uncouple. Motility characteristics of paired and single spermatozoa were measured in media of differing composition and viscosity by means of computer-aided semen analysis. In minimum essential medium or in RPMI 1640 medium alone, the absolute mean straight-line and curvilinear velocity values of paired spermatozoa (342 +/- 34 and 361 +/- 19 microns/sec, respectively, at 37 degrees C) were significantly greater than those of single spermatozoa (247 +/- 14 and 319 +/- 16 microns/sec), while mean lateral head displacement for paired spermatozoa (5.6 +/- 2.1 microns) was significantly less than for single spermatozoa (11.4 +/- 2.6 microns). However, when medium was made more viscous with polyvinyl pyrrolidone (0.8-82 poise) and sperm motility was calculated as a percentage of maximum attained velocity (in medium alone), there was no significant difference in straight-line or curvilinear velocity for single or paired spermatozoa in medium of the lowest viscosity (0.8 poise). In contrast, paired spermatozoa in medium of higher viscosity (above 1.92 poise) maintained straight-line velocity (e.g., 54 +/- 3% of maximum straight-line velocity in medium of 2.28 poise) while single sperm moved in tight circles and exhibited poor straight-line velocity (5 +/- 1% of maximum velocity). The data show that paired spermatozoa exhibit a significant motility advantage over single spermatozoa in a viscous medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

High developmental rates of vitrified bovine oocytes following parthenogenetic activation, in vitro fertilization, and somatic cell nuclear transfer.

Successful cryopreservation of mammalian oocytes would provide a steady source of materials for nuclear transfer and in vitro embryo production. Our goal was to develop an effective vitrification protocol to cryopreserve bovine oocytes for research and practice of parthenogenetic activation, in vitro fertilization, and nuclear transfer. Bovine oocytes matured in vitro were placed in 4% ethylene glycol (EG) in TCM 199 plus 20% fetal bovine serum (FBS) at 39 degrees C for 12-15 min, and then transferred to a vitrification solution (35% EG, 5% polyvinyl-pyrrolidone, 0.4 M trehalose in TCM 199 and 20% FBS). Oocytes were vitrified in microdrops on a precooled (-150 degrees C) metal surface (solid-surface vitrification). The vitrified microdrops were stored in liquid nitrogen and were either immediately thawed or were thawed after storage for 2-3 wk. Surviving oocytes were subjected to 1) parthenogenetic activation, 2) in vitro fertilization, or 3) nuclear transfer with cultured adult fibroblast cells. Treated oocytes were cultured in KSOM containing BSA or FBS for 9 to 10 days. Embryo development rates were recorded daily and morphologically high-quality blastocysts were cryopreserved for nuclear transfer-derived embryos at Day 7 or Day 8 of culture. Immediate survival of vitrified/thawed oocytes varied between 77% and 86%. Cleavage and blastocyst development rates of vitrified oocytes following in vitro fertilization or activation were lower than those of the controls. For nuclear transfer, however, vitrified oocytes supported embryonic development as equally well as fresh oocytes.

Animals↗
PubMed2002

Effect of the absence or presence of various protein supplements on further development of bovine oocytes during in vitro maturation.

The evaluation of culture medium for bovine oocytes has progressed toward more defined conditions during the last few years. The main objective of this study was to evaluate different sources of albumin as a protein supplement during in vitro maturation (IVM) of bovine oocytes in synthetic oviduct fluid medium (SOF). The replacement of protein with polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA) was also evaluated. The effect of recombinant human FSH on cumulus expansion and nuclear maturation in SOF containing BSA (BSA-V) or PVP-40 was also studied. Addition of BSA-V during IVM retarded nuclear maturation when compared with addition of PVP-40 or use of SOF alone. The inclusion of different concentrations of BSA-V, fetal calf serum (FCS), or PVA during IVM had no positive effect on the developmental capacity of the oocytes compared with the use of SOF alone with no supplement but significantly decreased the percentage of embryos reaching the morula and blastocyst stages. However, when BSA-V was replaced with purified BSA, BSA that was essentially free of fatty acids, or chicken egg albumin, embryonic development rates were restored. The presence of PVP-40 but not PVP-360 during IVM significantly increased morula and blastocyst production. These results indicate that although SOF alone can support bovine oocyte maturation, a high proportion of morulae and blastocysts can be produced from IVM oocytes cultured in medium containing PVP-40. These studies are the first to show that the effect of FSH on nuclear maturation and cumulus expansion is dependent on substrates present in IVM medium.

Animals↗
PubMed1987

A randomized study of two schedules of copovithane in patients with advanced colorectal carcinoma.

Copovithane (BAY i 7433), a copolymer of 1,3-bis(methylaminocarboxyl)-2-methylenepropanecarbamate and N-vinyl pyrrolidone, has antitumor activity in vitro and in vivo. The mechanism of this polymer is unknown. Thirty patients with advanced colorectal carcinoma with measurable tumors were treated in an open randomized study with two schedules of copovithane (schedule A: 6 g/m2 i.v. over 30 min daily for 5 consecutive days and repeated every 3 weeks; schedule B: 10 g/m2 i.v. over 30 min once a week until progression, unacceptable toxicity, or up to 18 months). Fifteen patients received copovithane on a weekly schedule, and 15 patients received it on an intermittent schedule. None of the patients on either schedule achieved a complete or partial remission. Copovithane was ineffective against colorectal carcinoma by both schedules selected in this study.

Antineoplastic Agents↗
PubMed2000

The dissolution vessel for plutonium pits at the U.S. DOE Pantex Plant.

The U.S. DOE Pantex Plant has been given the mission to recertify and requalify plutonium pits for reuse in existing War Reserve nuclear weapons. The first process common to both recertification and requalification is cleaning the plutonium pit. The pit will be cleaned in a dissolution vessel using N-methyl pyrrolidone (NMP) solvent. The recertification and requalification programs are both in the design concept phase at Pantex Plant The U.S. DOE Pantex Plant secures the national security of the United States by using safe vessels for cleaning plutonium pits in a manner that protects the health and safety of employees, the public and the environment.

Equipment and Supplies↗