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PubMedDate not supplied

Formation of a stable 99mTc-tri-hydrazidophosphine oxide (99mTc-THP) chelate.

Atri-hydrazidophosphine oxide (THP) ligand was synthesized and used to complex 99mTc in high yield (> 95%) by Sn(II) reduction of 99mTcO4-. 99mTc-THP has excellent stability in both 0.9% acqueous NaCl at neutral pH and in human serum at 37 degrees C. Biodistribution studies indicate minimal organ specificity and no significant in vivo release of 99mTcO4-. The ease of 99mTc complexation with THP and the high stability of 99mTc-THP suggests that this ligand may be used as a basis for the development of new imaging agents.

Animals↗
PubMed2003

[Efficiency of a new method for extrapleural plastic repair of the apex of the lung in disseminated destructive tuberculosis].

The Thoracic Department, Yarutsk Research Institute of Tuberculosis, has developed a new method for extrapleural plastic repair of the apex of the lung in destructive tuberculosis. The essence of the method is that pneumolysis of the apex of the lung and its bringing down is made by the well-known procedure described by L. K. Bogush after thoracoplasty. To prevent its expanding, the apex of the lung is fixed by a hammock mesh prepared before surgery. For this, No. 2 polysorb thresh is used and a 10 x 14-cm mesh is woven. The cells measure 2 x 2 cm. Then the mesh is placed in disinfectant solution. Surgery was performed in 41 patients with generalized fibrocavernous, disseminated, cavernous, and infiltrative pulmonary tuberculosis, by yielding 90.3% efficiency. The developed operation may be used during a non-stabilized tuberculous process, anterior and upper lung destructions and in the presence of a giant cavity in the lung tissue. The time course of changes in the indices of external respiratory function is indicative of a more rapid and qualitative recovery of the external respiratory apparatus and of a rapid adaptation of compensatory respiratory mechanisms in the postoperative period.

Adolescent↗
PubMedDate not supplied

[Extraction of crystalline L-threonine(serine)-dehydratase from rat liver].

Isolation on a preparative scale of crystalline pyridoxal phosphate-dependent threonine dehydratase (responsible for threonine deamination) from rat liver tissue is described. The enzyme was purified by stepwise salting out with (NH4)2SO4, two precipitations with acetone, gel filtration through Sephadex G-25, chromatography on DEAE cellulose, repricipitation with ammonium sulfate and crystallization. The ratio of threonine to serine dehydratase activities was altered only slightly through all the steps of the purification procedure. Both enzymes proved to be similar in their chromatographic properties; this suggests that a single enzyme is responsible for dehydrative deamination of both hydroxyamino acids in rat liver tissue. Stability of the enzyme preparations was distinctly increased after DEAE cellulose chromatography. The yield of crystalline threonine (serine) dehydratase was about 3%; the enzyme was purified 1500-1800-fold.

Animals↗
PubMedDate not supplied

Heat-denaturation of pig kidney diamine oxidase: effect of arcaine.

Pig kidney diamine oxidase is protected against heat denaturation by the presence of inhibitors like tetramethylene diguanine (arcaine). In the presence of inhibitor the enzyme retains its full activity even after 30 min. incubation at 60 degrees C. This inhibitor binds to the enzyme inducing small but significant absorption changes in the near uv spectrum. Temperature dependence of intrinsic fluorescence yield is different in the presence and absence of arcaine, indicating a conformational stabilizing effect of this inhibitor.

Amine Oxidase (Copper-Containing)↗
PubMed1983

Simultaneous regulation of amino acid influx and efflux by system A in the hepatoma cell HTC. Ouabain simulates the starvation-induced derepression of system A amino acid transport.

In the cultured hepatoma cell HTC, amino acid starvation stimulated both influx and efflux of 2-(methylamino)isobutyric acid (MeAIB) across the plasma membrane with little effect on the ultimate cellular accumulation of this amino acid. In agreement, prior amino acid starvation had little effect on the cellular steady state levels reached for various natural amino acids during subsequent incubation in an amino acid-rich medium containing cycloheximide. Furthermore, efflux of [14C]MeAIB was markedly increased by amino acid starvation. These findings do not mean that adaptive regulation of neutral amino acid transport is pointless. If membrane transport rather than metabolism is the rate-limiting step for net amino acid production or consumption, or becomes so during times of elevated formation or catabolism of an amino acid, then proportionate changes of both the opposed fluxes should enhance its net generation or consumption. Amino acid starvation enhances MeAIB-dependent Na+ influx. Alteration of the external [Na+] changes the Km, not the Vmax, for MeAIB influx when the degree of System A derepression is stabilized with cycloheximide. In both starved and unstarved cells, Km/Vmax for MeAIB entry yields a linear function with the reciprocal of the external [Na+], supporting at least for influx a rapid equilibrium-ordered kinetic model in which Na+ binds to the carrier site before the amino acid. Elevated cellular [Na+] obtained by ouabain treatment increased MeAIB efflux in parallel. Trans-inhibition of MeAIB influx by accumulated MeAIB, and as a related phenomenon by cellular Na+, was as effective in unstarved as in starved cells, showing independence of this kinetic phenomenon from adaptive regulation. The decreased MeAIB accumulation resulting from decreased influx and increased efflux occurring at high internal [Na+] applies both to unstarved and starved cells. We conclude that cellular Na+ accumulations, produced by increasing levels of ouabain, reversibly reduce the ability of MeAIB to repress System A because its interior concentration is prevented from rising, although transport in both directions continues; accordingly, the repressive signal appears to come from the internal amino acid levels rather than from occupation of the carrier site for System A flux.

3-O-Methylglucose↗
PubMed1978

Preparation of protease-free and ribonuclease-free pancreatic deoxyribonuclease.

When pancreatic DNase I is used as a specific biochemical reagent in the preparation of nuclear ribonucleic acids or nuclear proteins, freedom from contaminating ribonucleases or proteases is an important property of the enzyme preparation. A simple one-step procedure has been developed to effect complete removal of trypsin, chymotrypsin, and chymotrypsinogen by a combination of affinity chromatography and salting-out adsorption on lima bean protease inhibitor coupled to Sepharose (a column (0.9 X 60 cm) operated in series with a regeneratable 1-ml bed). Commercial preparations of DNase (about 10 mg) give a quantitative yield of the enzyme that is protease-free as evidenced by full stability for more than 10 days at pH 8 and 37 degrees C even in the absence of the protecting action of Ca2+. Removal of the last traces of RNase has been accomplished by affinity chromatography on a column (0.4 X 72 cm) of 5'-(4-aminophenyl-phosphoryl)-uridine 2'(3')-phosphate-Sepharose; the product is a highly active DNase that gives no detectable hydrolysis of RNA by assay on radioactive substrates.

Chromatography, Affinity↗
PubMed1981

Assessment of a rapid-L-lactate enzyme analyzer.

A semi-automatic L-lactate concentration analyzer using an enzyme electrode is compared with the slower and more complicated photometric method using LDH and NAD. The analyzer permits lactate determination in less than 3 minutes with only 100 microliters of sample. The results of comparative measurements carried out on whole blood and plasma are examined with regard to the principle of enzymatic measurement. Since the analyzer only measures plasma lactate, whole blood yields lower values than by photometric methods. The analyzer has good linearity, accuracy, stability, and reproducibility. The influence of blood metabolism on the values of lactate measured is discussed. The long term fiability, an essential feature for a clinical analyzer, is not investigated in this study.

Chemistry Techniques, Analytical↗
PubMed1994

Photolinker-polymer-mediated immobilization of monoclonal antibodies, F(ab')2 and F(ab') fragments.

Photolinker-polymer-mediated covalent immobilization of antibodies, F(ab') and F(ab')2 fragments has been achieved by light-dependent coupling procedures. Anti-alpha-foetoprotein (anti-AFP) monoclonal antibodies were covalently linked to microplates by layer-coating procedures, which entail antibody photoimmobilization to a photolinker-polymer-precoated surface. In this and the co-coating procedure described, diazirine-functionalized BSA (T-BSA) served as the multifunctional light-activatable linking agent (photolinker polymer). Prior to photo-activation, F(ab')2 or F(ab') fragments derived from anti-(prostate-specific antigen) monoclonal antibodies were mixed and co-coated with the photolinker polymer on to polystyrene microplates. The immunoreagents remained immunologically active after 350 nm irradiation (irradiance 0.7 mW.cm-2 for 20 min). Immuno-responses of photoimmobilized monoclonal anti-AFP antibodies were equivalent to signal intensities obtained with physically adsorbed antibodies. Photoimmobilization of anti-PSA F(ab') fragments in the presence of T-BSA revealed exponential binding characteristics indicating stabilizing molecular co-operativity of the BSA constituent. Co-coating procedures yielded 62 and 65% binding of applied 14C-labelled F(ab')2 and F(ab') fragments respectively. Covalency of antibody binding was inferred from: (i) the strict dependence of photoreagent availability; (ii) the light-dependence of the immobilization process; and (iii) the reversibility of immunocomplexation after acid treatment.

Adsorption↗
PubMed1996

Evaluation of affinity filters for protein isolation.

Affinity filters were investigated for their potential in the recovery of proteins from complex samples. The experiments covered membranes carrying high and low molecular weight affinity ligands as well as group and substance specific ones. For the ready-to-use affinity filters the specific protein binding capacity was determined and compared to that of the respective Sepharose affinity gels (Pharmacia). In the case of the pre-activated membranes the influence of the coupling chemistry on the affinity mediator concentration and the protein binding capacity were considered in the study. In the case of low molecular weight ligands (e.g. Cibacron Blue, Heparin) either type of membrane yielded stationary phases of a ligand concentration, binding capacity, resolution, and long term stability similar to that of the corresponding Pharmacia material. However, the membranes could be used at a higher flow rate than the columns, since they are less mass transfer limited and cause significantly less back pressure. The immobilization of high molecular weight ligands such as antibodies (immuno filtration) on the other hand, resulted in low ligand concentrations and worse antigen binding capacities whenever conventional immobilization procedures, e.g. epoxy group-based reactions, were used. In contradistinction, good results were obtained with tosyl- and tresyl activated membranes. Such membranes were successfully employed for the immobilization of monoclonal antibodies (mAb) and Concanavalin A. Concanavalin A and an anti gp 220/350 mAb were subsequently used to produce affinity filters for the isolation of a recombinant gp 220/350 Epstein-Barr virus surface antigen from culture supernatants of a Chinese hamster ovary cell line grown in protein-free medium.

Animals↗
PubMedDate not supplied

[Hygienic rationale for the allowable weight load of a daily training complex for schoolchildren].

Computed posturography (stabilography) was used to examine the locomotor function of 165 children from 1-11 forms under the influence of different real and model loads. Analysis of age-specific changes in their upright stability (by the data on the lateral velocity of the body's oscillations) yielded allowable load weights of a daily complete set for schoolchildren.

Adolescent↗
PubMed1992

Stabilities of antigen and antibody under elution conditions in immunoaffinity chromatography using monoclonal antibody.

In immunoaffinity chromatography using monoclonal antibody, the elution conditions of an antigen, recombinant alpha-amylase, were studied. From among various conditions, three elution methods that gave fairly good yields of antigen activity (pH 2.3-2.5, pH 12.3-12.5 and 0.1 M lithium 3,5-diiodo salicylate [LIS]) were selected and the stabilities of the antigen and the antibody were analyzed. The antigen seemed to be eluted from the immunoadsorbent due to partial denaturation of either the antigen or the antibody. LIS seemed to be a specific denaturant for the antibody and its action was reversible. In terms of the stability of the antigen and repeated use of the immunoadsorbent, LIS seemed to be the best reagent for elution in immunoaffinity chromatography.

Animals↗
PubMed2005

Expression, purification, and characterization of recombinant cyanovirin-N for vaginal anti-HIV microbicide development.

Cyanovirin-N (CV-N) is a prokaryotic protein under development as a topical anti-HIV microbicide, an urgent and necessary approach to prevent HIV transmission in at-risk populations worldwide. We have expressed recombinant CV-N as inclusion bodies in the cytoplasm of Escherichia coli. A purification scheme has been developed that exploits the physicochemical properties of this protein, in particular its stability in a harsh inclusion body purification scheme. Under the conditions developed, this system yields 140 mg of highly purified CV-N per liter of high-density cell culture, which represents a 14-fold increase over the best recombinant CV-N yield reported to date. This purification scheme results in monomeric CV-N as analyzed by SDS-PAGE, isoelectric focusing, and reverse phase- and size exclusion-HPLC. This recombinantly expressed and refolded CV-N binds to gp120 with nanomolar affinity and retains its potent anti-HIV activities in cell-based assays. The expression and purification system described herein provides a better means for the mass production of CV-N for further microbicide development.

Animals↗
PubMed2001

Physical stability of the blue pigments formed from geniposide of gardenia fruits: effects of pH, temperature, and light.

Fruits of Gardenia jasminoides contain geniposide which can be transformed to blue pigments by a simple modification. Colorless geniposide obtained from gardenia fruits by charcoal and silica gel column chromatographies was hydrolyzed with beta-glucosidase to yield genipin. The resulting genipin was transformed to blue pigments by reaction with amino acids (glycine, lysine, or phenylalanine). The stability of the blue pigments against heat, light, and pH was studied to examine the blue dye for possible use as a value-added food colorant. Thermal degradation reactions at temperatures of 60-90 degrees C were carried out at different pH levels within the range 5.0-9.0 (pH 5.0, acetate buffer; pH 7.0, phosphate buffer; and pH 9.0, CHES buffer). The blue pigments remained stable after 10 h at temperatures of 60-90 degrees C, and in some cases, more new pigments formed. The pigments were more stable at alkaline pH than neutral and acidic pH. Similarly, the pigments were stable under light irradiance of 5000-20 000 lux. In this case, pH effect was not significant.

Drug Stability↗
PubMed2003

Development of a fed-batch cultivation strategy for the enhanced production and secretion of cutinase by a recombinant Saccharomyces cerevisiae SU50 strain.

Saccharomyces cerevisiae SU50 strain was cultivated with different concentrations of glucose and galactose with the aim of increasing cutinase activity, cutinase yield on the carbon source, and bioreactor productivity. Cultivations in shake flasks with galactose as the sole carbon source, with sugar concentrations between 10 and 40 g/l, exhibited growth-associated cutinase production and a constant specificity of cutinase secretion. Furthermore, as the galactose concentration increased to values higher than 15 g/l, a progressively higher maximum specific galactose consumption rate and a consequent higher alcoholic fermentation occurred, resulting in progressively lower biomass yields on the carbon source and cutinase yields on biomass. Using high glucose and galactose concentrations in a well-aerated bioreactor resulted in a high biomass productivity (0.5 g dcw/l/h), a high cutinase yield on biomass (21.5 U/mg dew), a final high cutinase secretion efficiency (97%), and plasmid stability (99%). Based on these studies, a two phase fed-batch cultivation strategy was developed. A batch phase with high glucose and galactose concentrations, followed by a fed-batch with a constant feed rate with galactose as the sole carbon source in order to minimize the repression of the GAL 7 promoter, were established. The feed rate was estimated to maintain a pre-determined concentration of galactose (20 g/l) on the culture medium in order to maximize the efficiency of cutinase secretion and minimize the galactose alcoholic fermentation. By this cultivation strategy, enhancements of 3.6-fold in cutinase activity, 1.2-fold in cutinase yield on the carbon source, and 8.7-fold culture productivity were obtained in relation to a batch cultivation performed in shake flasks with 20 g/l of galactose.

Journal Article↗
PubMed1997

Stability of parenteral midazolam in an oral formulation.

Midazolam is increasingly being used for oral sedation in pediatric dentistry. Unfortunately, it is available only as a parenteral formulation in Canada and the United States. Preparation of the parenteral solution for oral use is not uniform and leads the clinician to question the stability of this drug when used in conjunction with these vehicles. Therefore, the purpose of this study was to investigate the chemical stability of parenteral midazolam as an oral formulation to determine its expiry date. This was evaluated using a validated stability-indicating liquid chromatographic method. Midazolam was diluted in orange-flavored syrup to yield concentrations of 0.35, 0.64, and 1.03 mg/ml and then stored at room temperature. Samples were drawn on each of 9 study days (0, 1, 2, 6, 7, 9, 13, 21, and 102) and chromatographed. On each study day, solutions were inspected visually for changes in color, clarity, and appearance of particulate matter. Midazolam concentrations were considered within acceptable limits if they were not less than 90% of the initial concentration. Over the 102-day study period, there was no significant change in concentration in any of the solutions. On day 102, the remaining midazolam was within 7% of the day zero concentration. Therefore, these formulations of midazolam are stable at room temperature for a period of 102 days and would be suitable for clinical use.

Administration, Oral↗
PubMed2004

Rheological properties of highly concentrated protein-stabilized emulsions.

We prepared concentrated quasi monodisperse hexadecane-in-water emulsions stabilized by various proteins and investigated their rheological properties. Some protein-stabilized emulsions possess remarkably high elasticity and at the same time they are considerably fragile--they exhibit coalescence at yield strain and practically do not flow. The elastic storage modulus G' and the loss modulus G" of the emulsions were determined for different oil volume fractions above the random close packing. Surprisingly, the dimensionless elastic moduli G'/(sigma/a), sigma being the interfacial tension, and a being the mean drop radius, obtained for emulsions stabilized by different proteins do not collapse on a single master curve. They are almost always substantially higher than the corresponding values obtained for equivalent Sodium Dodecyl Sulfate (SDS)-stabilized emulsions. The unusually high elasticity cannot be attributed to a specificity of the continuous phase, because the osmotic equation of state of our emulsions is found identical to the one obtained for samples stabilized by classical surfactants. In parallel, we mimicked the thin films that separate the droplets in the concentrated emulsion and found that the protein adsorption layers contain a substantial number of sticky surface aggregates. These severely obstruct local rearrangements of individual drops in respect to their neighbors which leads to coalescence at yield strain. Furthermore, we found that G'/(sigma/a) is correlated (for a given oil volume fraction) to the dilatational elastic modulus, of the protein layer adsorbed on the droplets. The intrinsic elasticity of the protein layers, together with the blocked local rearrangements are considered as the main factors determining the unusual bulk elasticity of the studied emulsions.

Animals↗
PubMed1997

Thermodynamic characterizations of an intramolecularly hydrogen bonded C5-structure across proteinogenic residue.

Thermodynamic investigations of a smallest possible intramolecularly hydrogen bonded C5-structure, across a Thr residue, in model peptides Boc-Xxx-Thr-NH2 (Xxx = Ile, 1 or Leu, 2), indicated unusual thermal stability of the structure in non-polar medium. An analysis of van't Hoff plots, constructed from variable temperature 1H NMR data, yielded the thermodynamic parameters of a hydrogen bonded five-membered ring. The non-significance of the spatial organizations of the preceding CdeltaH3 bearing hydrophobic proteinogenic residue on the thermal stability of the C5-structure has been observed. The results revealed that the contribution of this element of secondary structure is quantifiable and the stability appeared to be roughly comparable to other intramolecularly hydrogen bonded reverse turn structures frequently observed in polypeptides and proteins.

Amides↗
PubMed2006

A new synthesis of sulfonamides by aminolysis of p-nitrophenylsulfonates yielding potent and selective adenosine A2B receptor antagonists.

1-Propyl- and 1,3-dimethyl-8-p-sulfophenylxanthine (PSB-1115 and SPT) were used as starting compounds for the development of adenosine A(2B) receptor antagonists with a sulfonamide structure. Since standard reactions for sulfonamide formation failed or resulted in very low yields, we developed a new method for the preparation of sulfonamides. p-Nitrophenoxide was used as a suitable leaving group with well balanced stability-reactivity properties. A large variety of amines, including aniline, benzylamine, phenethylamine, propylamine, butylamine, 2-hydroxyethylamine, aminoacetic acid, and N-benzylpiperazine reacted with p-nitrophenoxysulfonylphenylxanthine derivatives yielding the desired sulfonamides in satisfying to very good yields. The obtained sulfonamides were much more potent at A(2B) receptors than the parent sulfonates. The most active compound of the present series was 8-[4-(4-benzylpiperazide-1-sulfonyl)phenyl]-1-propylxanthine (11, PSB-601) exhibiting a K(i) value of 3.6 nM for the human A(2B) receptor combined with high selectivity versus the other human adenosine receptor subtypes (575-fold versus A(1), 134-fold versus A(2A), and >278-fold versus A(3)).

Adenosine A2 Receptor Antagonists↗