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PubMedDate not supplied

Mechanical analysis of elasticity and flexibility of virgin and polymer-treated hair fiber assemblies.

The elasticity and flexibility of virgin and polymer-treated hair fiber assemblies were investigated by employing straight hair tresses or hair shaped into omega loops. Polymer treatment was accomplished by saturating fibers with polymeric solutions, resulting in a deposition of 10-90 mg of polymer per gram of hair. The mechanical testing procedure consisted of subjecting omega-loop-shaped hair or straight hair tresses to multiple bending deformations at 25% strain in a texture analyzer. A total of ten deformations were typically carried out, and elasticity or flexibility parameters were evaluated from data such as (a). the force at 8% deformation, i.e., within the elastic region of bending deformation for hair shaped into an omega loop, (b). maximum force in the first (F(1)) and tenth (F(10)) deformation cycles, (c). elastic modulus in the first (E(1)) and tenth (E(10)) deformation cycles, and (d). the change in hair sample dimensions between the first (H(1)) and tenth (H(10)) deformation cycles. Parameters such as stiffness ratio (1), F(10)/F(1), E(10)/E(1), and H(10)/H(1) were employed to characterize hair tress rigidity, flexibility or resistance to breakage, and plasticity. Untreated hair was found to be almost perfectly elastic and flexible at 50% RH, evident by the linear dependence of force vs deformation. Flexibility parameters F(10)/F(1), E(10)/E(1), and H(10)/H(1) were in the range of 0.95 to 1.0 at low humidity, while the parameters F(10)/F(1) and E(10)/E(1) and were 10% lower at 90% RH. Examination of polymer-modified hair allowed for classification of treatments into categories termed brittle, quite flexible and nonplastic, flexible and plastic, very flexible and very plastic, and very flexible and nonplastic. Poly(vinyl pyrrolidone) is shown as an example of a quite flexible and nonplastic material, with its flexibility and stiffness dependent upon its molecular weight. The effect of plasticizers on polymer behavior is also discussed.

Animals↗
PubMed2003

A study of 5-aminolevulinic acid and its methyl ester used in in vitro and in vivo systems of human bladder cancer.

The use of 5-aminolevulinic acid and its esters to induce endogenous porphyrins for the purpose of detection of epithelial cancers is being studied extensively in many centres around the world. The challenge is to prepare an efficacious formulation for the purpose of cancer detection. Photodynamic diagnosis of cancer using 5-aminolevulinic acid (ALA) and its ester derivatives is being actively investigated. In this study, we compared ALA with ALA methyl ester (AME) derivative in terms of PpIX fluorescence intensity in in vitro and in vivo systems of bladder carcinoma. For the in vivo system consisting of RT112 xenografts, the modes of drug administration compared were intravenous administration and topical application. The Karl Storz fluorescence endoscopy system was used to obtain macroscopic fluorescence images. The macroscopic images were further analysed for fluorescence intensity distribution. For the intravenous administration, over all time points studied (1, 3, 6 h), AME-PpIX fluorescence was lower than ALA-PpIX fluorescence and was cleared at a faster rate than the ALA-PpIX when administered intravenously. Topical application with two different polymers, Gantrez and Polyvinyl pyrrolidone (PVP) which are fast releasing polymers was found to be comparable in inducing PpIX fluorescence. Topical AME-PpIX fluorescence was found to be comparable with ALA-PpIX fluorescence. The results of this study suggest that the AME can also be used as a good diagnostic agent.

Administration, Topical↗
PubMed1992

N-methyl-D-aspartic acid (NMDA) and non-NMDA receptors regulating hippocampal norepinephrine release. III. Changes in the NMDA receptor complex induced by their functional cooperation.

N-methyl-D-aspartic acid (NMDA) and non-NMDA ionotropic receptors mediating increase of norepinephrine (NE) release coexist on NE rat hippocampus axon terminals. Activation of non-NMDA receptors permits activation of NMDA receptors also in presence of Mg++ ions and induces important changes in the NMDA receptor recognition site and in its intrinsic ion channel. We have now studied the effects of this receptor-receptor interaction on the glycine site of the NMDA receptor by using two antagonists, 7-chloro-kynurenic acid and (+-)-3-amino-1-hydroxy-2-pyrrolidone (HA-966). Both the [3H]NE releases induced from rat hippocampus synaptosomes by NMDA (no Mg++ added) and by NMDA+quisqualic acid (QA), in the presence of 1.2 mM Mg++, were prevented by 7-chloro-kynurenic acid with almost identical potency (IC50 values: 0.19 and 0.39 microM, respectively). In contrast, HA-966, up to 1000 microM, was ineffective toward NMDA (no Mg++), but it blocked the effect of NMDA + QA in presence of Mg++ (IC50 = 1.1 microM). HA-966 also antagonized NMDA + QA in Mg(++)-free medium. Thus coactivation of non-NMDA and NMDA receptors seems to permit the antagonistic activity of HA-966. In the presence of Mg++, L-glutamic acid (L-Glu) enhanced [3H]NE release. The sensitivity of the L-Glu effect to various antagonists was similar to that of the effect of NMDA + QA, indicating that the NMDA receptor complex activated either by NMDA + QA or by the physiological transmitter L-Glu in presence of Mg++ ions undergoes dramatic conformational changes at the recognition site, at the ion channel as well as at the glycine site.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1992

Prodrugs of peptides. 19. Protection of the pyroglutamyl residue against pyroglutamyl aminopeptidase by N-acyloxymethylation and other means.

The N-terminal pyroglutamyl group in several peptides is specifically cleaved by pyroglutamyl aminopeptidase (PAPase I). With the aim of protecting this group against enzymatic cleavage by the prodrug approach, various derivatives of L-pyroglutamyl benzylamide, used as a PAPase I sensitive model pyroglutamyl peptide, were prepared and their stability characteristics determined. The derivatives studied included phenoxycarbonyl, phthalidyl, hydroxymethyl and actoxymethyl derivatives, all formed at the pyroglutamyl NH-moiety. Whereas L-pyroglutamyl benzylamide was rapidly hydrolyzed by PAPase I, all the derivatives were resistant to cleavage by the enzyme. On the other hand, these derivatives, with the exception of the N-phenoxycarbonyl derivative, were readily converted to the parent pyroglutamyl benzylamide by spontaneous or plasma catalyzed hydrolysis, the half-lives of conversion in 80% human plasma being in the range 2.3-8.4 h. The major degradation reaction of the N-phenoxycarbonyl derivative in both buffer and plasma solutions was hydrolytic opening of the pyrrolidone ring. The pH-rate profiles for the degradation of the compounds in aqueous solution were obtained and both specific acid and base catalytic reactions as well as a spontaneous reaction were observed. The results suggest that N-phthalidylation, N-hydroxymethylation and N-acyloxymethylation of pyroglutamyl peptides may be useful prodrug approaches to protect such peptides against cleavage by pyroglutamyl aminopeptidase and hence to improve their delivery characteristics.

Humans↗
PubMed1992

High affinity [3H]dextrorphan binding in rat brain is localized to a noncompetitive antagonist site of the activated N-methyl-D-aspartate receptor-cation channel.

[3H]Dextrorphan recognition sites were characterized in rat brain membranes. The pharmacological profile and regional distribution of [3H]dextrorphan binding sites appear to distinguish these sites from those labeled either by [3H]dextromethorphan or by putative sigma receptor radioligands. Data from thoroughly washed forebrain membranes suggest that [3H]dextrorphan predominantly labels a high affinity site defined by the activated state of the N-methyl-D-aspartate (NMDA) receptor-channel complex. Regulation of [3H]dextrorphan binding by specific modulators of NMDA receptor function suggests that [3H]dextrorphan binding is predominantly localized to a domain of the receptor-channel complex also recognized by the prototypical noncompetitive antagonist radioligands (+)-[3H]5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imi ne (MK-801) and [3H]1-[1-(2-thienyl)cyclohexyl]piperidine (TCP). The critical relationship between [3H]dextrorphan binding and activation of the NMDA receptor-complex is suggested by the profound dependence of [3H]dextrorphan binding on glutamate in well washed membranes. Basal specific [3H]dextrorphan binding is nearly totally suppressed by the specific competitive NMDA antagonist D(-)-2-amino-5-phosphonopentanoic acid (D-AP5), in a glutamate- but not glycine-surmountable manner. Glutamate and glycine each stimulate [3H]dextrorphan binding in a concentration-dependent manner, effecting maximal increases from control of up to 30- and 14-fold, respectively. The NMDA receptor specificity of the modulation of [3H]dextrorphan binding by glutamate and glycine is indicated by the sensitivity of their effects to competitive antagonism by D-AP5 and 3-amino-1-hydroxy-2-pyrrolidone (HA-966), respectively, and by the accordant rank orders of potency of glycine analogs as modulators of [3H]dextrorphan binding and as ligands at the strychnine-insensitive glycine site. The divalent cations Mg2+ and Zn2+ and the polyamines spermine and spermidine regulate [3H]dextrorphan binding in a manner consistent with radioligand interaction at the noncompetitive NMDA antagonist domain. Mg2+ and spermidine regulate [3H]dextrorphan binding biphasically in well washed forebrain membranes, whereas Zn2+ monotonically inhibits [3H]dextrorphan binding. Mg2+ and spermidine regulate [3H]dextrorphan binding with qualitative similarity and in a contrasting fashion to their regulation of [3H]MK-801 and [3H]TCP binding. First, spermidine and Mg2+ are significantly more potent modulators of [3H]dextrorphan binding than of [3H]MK-801 and [3H]TCP binding in well washed membranes; second, whereas the potencies of spermidine and Mg2+ as modulators of [3H]MK-801 and [3H]TCP binding are significantly increased by glutamate and glycine in well washed membranes, their potencies as regulators of [3H]dextrorphan binding appear to be unaffected by glutamate and glycine.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

[X-ray diffraction studies on tolbutamide solid dispersion].

D860 (tolbutamide) solid dispersions prepared with urea, polyvinyl pyrrolidone (PVP), and polyethylene glycal (PEG) 6000 as carriers were studied by X-ray diffraction, relating to their dissolution rates. D860 in D860-PVP dispersion was shown to be in an amorphous state and to have greater dissolution rate. D860-urea and D860-PEG melts were found to be partly in miscible solid solution state and partly in microcrystal state and possess higher activity and greater dissolution rate. D860-PEG coprecipitate was a physical mixture and its dissolution rate is slower than its melt. No variation in the crystal structure of the D860 dispersions was observed during the ageing test.

Drug Carriers↗
PubMed1992

Oral magnesium supplementation improves fetal circulation.

It is well known that pregnancy is a condition in which plasma magnesium falls because of accumulation of the ion in the placenta and fetus. Magnesium (Mg) is therefore widely given as a supplement during pregnancy, particularly in cases of preterm labour. In our experience, the combination of oral Mg (magnesium pyrrolidone carboxylic acid) at a dose of 360 mg/day with conventional ritodrine treatment allows a reduction in ritodrine dosage, accompanied by a significant reduction in side effects. We therefore evaluated changes in fetal blood flow, using pulsed Doppler, in women submitted to combined magnesium and ritodrine treatment compared to those treated with ritodrine plus placebo. The Mg-treated group showed a decrease in vessel resistance both in the umbilical artery and in the fetal middle cerebral artery, indicating that fetal vasculature is sensitive to exogenous Mg. Measurement of plasma and mononuclear cell Mg showed an intracellular increase in the cation of about 10 per cent. We conclude that oral magnesium supplementation in pregnancy is safe and that it has a positive effect on the fetal circulation.

Cerebral Arteries↗
PubMed2003

Matrix type transdermal drug delivery systems of metoprolol tartrate: in vitro characterization.

The monolithic matrix type transdermal drug delivery system of metoprolol tartrate were prepared by the film casting on a mercury substrate and characterised in vitro by drug release studies, skin permeation studies and drug-excipients interaction analysis. Four formulations were developed, which differed in the ratio of matrix-forming polymers. Formulations MT-1, MT-2, MT-3 and MT-4 were composed of Eudragit RL-100 and polyvinyl pyrrolidone K-30 with the following ratios: 2:8, 4:6, 6:4 and 8:2, respectively. All the four formulations carried 10% (m/m) of metoprolol tartrate, 5% (m/m) of PEG-400 and 5% (m/m) of dimethyl sulfoxide in isopropyl alcohol: dichloromethane (40:60). Cumulative amounts of the drug released in 48 hours from the four formulations were 61.5, 75.4, 84.3 and 94.5%, respectively. The corresponding values for cumulative amounts of the permeated drug for the said formulations were 53.5, 62.5, 69.8 and 78.2%. On the basis of in vitro drug release and skin permeation performance, formulation MT-4 was found to be better than the other three formulations and it was selected as the optimized formulation.

Administration, Cutaneous↗
PubMed2003

Design and characterization of mucoadhesive buccal patches containing cetylpyridinium chloride.

Mucoadhesive patches for delivery of cetylpyridinium chloride (CPC) were prepared using polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC) and chitosan. Swelling and bioadhesive characteristics were determined for both plain and medicated patches. The results showed a remarkable increase in radial swelling (S(D)) after addition of the water-soluble drug (CPC) to the plain formulae. A decrease in the residence time was observed for PVA and chitosan-containing formulae. Higher drug release was obtained from PVA patches compared to HEC ones, while both are non-ionic polymers. A considerable drop in release was observed for chitosan formulae after the addition of water-soluble additives, polyvinyl pyrrolidone (PVP) and gelatin. Ageing was done on PVA formulae; the results showed there was no influence on the chemical stability of CPC, as reflected from the drug content data. Physical characteristics of the studied patches showed an increase in the residence time with storage accompanied with a decrease in drug release. This may be due to changes in the crystal habit of the drug as well as to slight agglomeration of the polymer particles.

Adult↗
PubMedDate not supplied

[Functional-behavioral profile of new cyclic GABA analogs in acute toxicity tests].

The properties of karphedone and phepyrone--new phenyl derivatives of pyrrolidone possessing nootropic activity--were studied in the course of the acute toxicity tests on rats. The drug effects were evaluated in terms of their integral influence on the state and behavior of test animals. The real therapeutic range and the profit/risk ratio of karphedone were comparable with those of the reference drug pyracetam and exceeded by a factor of 1.3 the corresponding values for phepyrone (irrespective of the LD50 values). The results give grounds for the further preclinical investigation of karphedone.

Animals↗
PubMed1992

Application of the chloramphenicol acetyltransferase (CAT) diffusion assay to transgenic plant tissues.

Chloramphenicol acetyltransferase (CAT) activity was quantified in crude extracts from tobacco callus tissues using a modification of a previously reported diffusion assay. We describe here the alterations necessary in applying this rapid and simple assay procedure to plant materials. Due to the high concentration of nonspecific oxidases present in most plant tissues, some type of protective agent is required to maintain enzyme activity. We have tested beta-mercaptoethanol, cysteine, dithiothreitol, ascorbic acid and polyvinyl pyrrolidone as protective agents within the initial extraction buffer. We also investigated the effect of heat (60 degrees C, 10 min) and 5 mM EDTA on CAT activity. The highest CAT activity was obtained using 5 mM cysteine plus 5 mM EDTA in 40 mM Tris-HCl (pH 7.8) as the initial extraction buffer followed by a heat treatment. Using this buffer, CAT activity was stable on ice for more than two hours. In our hands, total acetyl-coenzyme A concentration within the assay mixture was found to be saturating at 250 microM and the Km determined to be 100 microM. Assays performed using the same crude plant extract indicate that 1) duplicate assays show less than 1.5% variation in activities and 2) CAT activity increases linearly with respect to volume of extract used.

Chloramphenicol O-Acetyltransferase↗
PubMed2005

[Synthesis and SERS characterization of silver nanocubes].

Silver nanocubes were synthesized by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) based on the report by Xia's group. Silver nanocubes were immobilized on silicon wafers by self-assembly processes. SERS activity of silver nanocubes was detected by using pyridine and SCN- respectively as probe molecules. The preliminary results show that the Raman intensities of pyridine and SCN- adsorbed at silver nanocubes were enhanced considerably, indicating that silver nanocubes can be used as a good SERS substrate. On the other hand, SERS combined with the probe molecule method can be used to characterize the optical property of silver nanocubes.

Ethylene Glycol↗
PubMed2005

Ocular inserts for controlled delivery of pefloxacin mesylate: preparation and evaluation.

Pefloxacin mesylate is a flouroquinolone antibacterial drug effective in the treatment of bacterial conjunctivitis. The objective of the present work was to develop ocular inserts of pefloxacin mesylate and evaluate their potential for sustained ocular delivery. Reservoir-type ocular inserts were prepared by the film casting technique in teflon coated Petri dishes and characterized in vitro by drug release studies using a flow-through apparatus that simulated the eye conditions. Six formulations were developed, which differed in the ratio of polymers Eudragit RS 100 and Eudragit RL 100 used for the preparation of the rate controlling membrane. All formulations carried 0.72 mg pefloxacin mesylate, 2.69 mg polyvinyl pyrrolidone (PVP) K-30, plasticizers, propylene glycol (10% m/m) and dibutyl phthalate (15%, m/m). The optimized formulation was subjected to microbiological studies, in vivo studies, interaction studies, and stability studies to assess the effectiveness of the formulation. Cumulative drug released from the formulation ranged from 90-98% within 48 to 120 hours. On the basis of in vitro drug release studies, the formulation with Eudragit RS 100/Eudragit RL 100 (4:1) was found to be better than the other formulations and it was selected as an optimized formulation. On the basis of in vitro, microbiological, in vivo drug release, interaction and stability studies, it can be concluded that this ocular insert formulation provided the desired drug release in vitro for 5 days and remained stable and intact at ambient conditions.

Acrylic Resins↗
PubMed2005

[The therapeutic effect of metadoxine on alcoholic and non-alcoholic steatohepatitis].

The therapeutic effect of metadoxine on alcoholic and non-alcoholic steatohepatitis. Alcohol-induced liver disease is one of the main epidemic problems of nowadays. Non-alcoholic steatohepatitis has been described only for some years, but it also needs much more attention in the future. The etiologic factors of both entities are quite different, but the pathologic changes of the liver are nearly the same, therefore there could be certain drugs, that are equally effective in their therapy. Metadoxine is one of them, mainly because its protective effect against the damage done by free radicals. Metadoxine is a pyridoxine-pyrrolidone carboxylate with significant scavenging property. There are a lot of patients suffering from steatohepatitis, and they will face the complications of the liver damage. The aim is to provide better recovery and proper quality of life, which is based on the deeper understanding of these mechanisms. Metadoxine is suitable for increasing reduced glutathione level, which is very important for the redox homeostasis of the liver and the whole body. The effectiveness of the drug is established both in acute and in chronic alcoholism, moreover it helps in staying abstinent.

Alcohol Deterrents↗
PubMedDate not supplied

Modeling of drug release from celecoxib-PVP-meglumine amorphous systems.

An empirical assessment of drug release from amorphous systems of celecoxib (CEL), poly(vinyl pyrrolidone) (PVP), and meglumine (MEG) was performed and compared with that for its crystalline form. CEL-PVP (4:1 w/w) binary and CEL-PVP-MEG (7:2:1 w/w) ternary amorphous systems provided higher drug dissolution. Mathematical modeling of drug release data was found to best fit the Hixson-Crowell release model. The biphasic drug release during a 6-h duration exhibited higher release kinetics in the first phase due to the presence of drug in amorphous form. The release kinetics subdued in the latter phase due to ongoing devitrification process in amorphous systems. A comprehensive understanding of drug release from amorphous systems will accentuate the rationalized design of amorphous drug delivery systems.

Celecoxib↗
PubMed2006

The effect of commonly used vehicles on canine hematology and clinical chemistry values.

Drug metabolism and pharmacokinetic (DMPK) studies are an important phase in drug discovery research. Compounds are administered via the intravascular or extravascular routes to animals to calculate various pharmacokinetic parameters. An important step in this process is dissolving the novel compound in a safe vehicle. This procedure is particularly challenging for compounds that must be administered intravenously, as the solution must be clear before injection. There are no published guidelines on which vehicles, or combination of vehicles, are acceptable in a particular species, nor are there published data on the effects these vehicles have on clinical chemistry or hematology parameters, particularly in dogs. In this study, 9 vehicles commonly used at sanofi-aventis USA (propylene glycol, polyethylene glycol 400, glycofurol, hydroxypropyl Beta-cyclodextrin, dimethyl sulfoxide, N-methyl-2-pyrrolidone, dimethylacetamide, ethyl alcohol, and saline) were tested for adverse clinical reactions (such as vomiting or diarrhea) and for their effect on hematology and clinical chemistry parameters. Each vehicle was administered to a group of 8 Beagles by slow intravenous infusion, and blood was collected prior to infusion and at 24 h and 7 d postinfusion. Of 8 dogs given propylene glycol, 2 developed mild gastrointestinal signs (vomitus, diarrhea) after their infusions. None of the vehicles tested induced significant hematology or serum clinical chemistry abnormalities, nor were significant clinical signs noted after administration. We conclude that at the dose, route, and manner described, all of the vehicles tested in this study are clinically safe to use and have no acute effects on hematology or serum chemistry parameters.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1991

Alcoholic abstinence syndrome: short-term treatment with metadoxine.

The effects of metadoxine (pyrrolidone carboxylate of pyridoxine), a compound with central benzodiazepine-like properties, were evaluated in two groups of chronic alcoholics (inpatients) presenting a mild withdrawal syndrome. According to a double-blind study design 20 patients received metadoxine 900 mg twice daily eluted in 500 ml of saline infusion, while 20 (the control group) were given 500 ml of saline infusion twice daily with equivalent doses of pyridoxine (40 mg/die) every morning over a 10-day period. The results indicate that metadoxine treatment was able to control alcohol abstinence, thus allowing a reduction in the needs for standard benzodiazepine therapy. The central activity of gamma-aminobutyric acid of this compound might play a crucial role in the clinical effects demonstrated.

Adult↗
PubMed1990

Regulation of [3H]dopamine release from guinea pig striatum by NMDA receptor/channel activators and inhibitors.

Excitatory amino acids, that interact with the N-methyl-D-aspartate (NMDA) receptor stimulate release of [3H]dopamine [3H]DA) from the striatum of the guinea pig and rat in a concentration-dependent manner. DA release was measured in the presence of domperidone and nomifensine to avoid complications associated with autoreceptor alteration of and reuptake of released DA. This release is inhibited by magnesium. Therefore, all experiments were performed in the absence of this ion. The competitive NMDA antagonists D-(-)2-amino-5-phosphonopentanoic acid and 3-[(+-)-2-carboxypiperazin-4-yl]-propyl-1-phosphonic acid and the noncompetitive antagonists (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine and phencyclidine also inhibit NMDA-stimulated release. Glycine enhances NMDA-stimulated release and can release [3H]DA in the absence of added NMDA. Release stimulated by glycine alone is not affected by 3-[(+-)-2-carboxypiperazine-4-yl]-propyl-1-phosphonic acid. Conversely, if the glycine antagonist 3-amino-1-hydroxy-2-pyrrolidone or 6-cyano-7-nitroquinoxaline-2,3-dione is included, NMDA elicits less release of [3H]DA. This inhibition can be overcome by increasing the concentration of glycine. The kappa-selective opioid agonist trans-(+-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]-benzene-acetamide is also capable of inhibiting the NMDA-stimulated release of [3H]DA from guinea pig and rat striatum.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗