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PubMed1992

Identification of essential histidine residues in rat type I iodothyronine deiodinase.

Deiodination is required for conversion of thyroxine, the inactive prohormone secreted by the thyroid gland, to 3,5,3'-triiodothyronine, the biologically active thyroid hormone. The principal enzyme catalyzing this reaction, Type I iodothyronine 5' deiodinase, was shown recently to contain the amino acid, selenocysteine, and site-directed mutagenesis showed that this amino acid confers the biochemical properties characteristic of this enzyme. Previous studies suggest that a histidine residue may also be critical for activity. To further our understanding of the biochemical mechanism of this reaction, we have used in vitro mutagenesis to examine the contribution of each of the 4 histidines in this enzyme to the deiodination process. Two of the histidines (185 and 253) are not involved in deiodination, as their removal had no effect on activity. Mutagenesis of histidine 158 resulted in complete loss of activity, suggesting a role in either protein conformation or catalysis. The most informative results were obtained from the studies of histidine 174. Mutagenesis of this histidine to asparagine or glutamine altered reactivity with substrate and reduced inhibition by diethylpyrocarbonate and rose bengal. These results demonstrate that histidine 174 is critical to function and appears to be involved in binding of hormone.

Amino Acid Sequence↗
PubMedDate not supplied

Further studies on the physico-chemical properties of Rhizopus nodosus acid lipase.

The Km value of R. nodosus acid lipase was found to be 5 X 10(-2) M and 8 X 10(-3) M with olive oil and tricaprylin respectively. The lipase hydrolyzed triglycerides better than synthetic detergents and methyl esters. When synthetic triglycerides varying in fatty acid chain length were used, maximum hydrolysis was observed with tricaprylin as the substrate. Positional specificity studies indicated a preference for primary esters. The lipase was activated by albumin, NaCl and taurocholate whereas heparin had no effect. The lipase contains a single polypeptide chain with 298 amino acid residues. Glutamic acid and isoleucine were found to be the amino and carboxy-terminal residues, respectively. By gel filtration and SDS-PAGE the molecular weight was determined to be 40,000 +/- 500. The lipase was susceptible to photooxidation in the presence of methylene blue and Rose bengal whereas PMSF and thiol-group specific reagents had no appreciable effect on the lipase activity. NBS inactivated the lipase. Tryptophan residues were found to be essential for the lipase activity.

Kinetics↗
PubMed1980

The pH dependence of rat liver RNA polymerases I and II.

The effect of pH on the stability and activity of rat liver RNA polymerases I (A) and II (B) has been studied. Both enzymes are irreversibly inactivated in buffer solutions below pH 5.0. Km values of the two enzymes are constant between pH 6.5 and 8.7 but a two -to three- fold increase is observed between pH 8.7 and 9.7. The Vmax versus pH profiles are bell-shaped curves indicating the participation of two ionizing groups with apparent pKa values of 6.5 and 9.8 for enzyme I and 6.7 and 9.9 for enzyme II. Both enzymes are inactivated by photooxidation in the presence of Rose Bengal. It is suggested that the above pKa corresponds to the imidazole of a histidine residue and a amino group of a lysine residue.

Animals↗
PubMed1980

Spheroid degeneration of conjunctiva and cornea. Two years' follow up.

Twenty-six subjects with spheroid degeneration were followed up after two years. The number of colourless conjunctival droplets was seen to have increased by on an average 46% (2 alpha = 0.05) and that of autofluorescent conjunctival droplets by 223% (2 alpha less than 0.01). Counting within the individual sites sites disclosed that some droplets will disappear (not less than 30 and 21% respectivelY), while recently formed will constitute at least 76 and 243%. The number of areas with band-shaped keratopathy was found to rise from 3 to 26 (P less than 0.001) out of 104 possibilities, (nasally and temporally of right and left eye). Vital staining (fluorescein, rose bengal, tetrazolium, alcian blue) showed the epithelium above the droplets to be intact, and the droplet-containing eyes were found not to be abnormally dry (break up time, tear production).

Alcian Blue↗
PubMed1975

[Study on the inhibition of testicular polyadenylate polymerase stimulated by manganese].

Many different types of naturally occurring substances and of drugs were examined as potential inhibitors of a Mn++-stimulated and poly(A)-primed polyadenylate polymerase that was partially purified from rat testis. By far the most active inhibitors were anionic dyes that were either of the diazo naphthyl sulfonate category, such as Evans Blue, or were halogenated derivatives of fluorescein, like Rose Bengal. The characteristics of these in vitro inhibitions, which did not involve any photo-sensitized reactions, were examined in considerable detail.

Animals↗
PubMedDate not supplied

Biochemical activities of propolis extracts. II. Photodynamic activities.

Ethanolic and aqueous extracts of the "bee glue" Propolis exhibit antioxidative properties and are used as antiinflammatory drugs in folk medicine. In order to standardize the principle activities of prominent components of these extracts, simple biochemical tests have been introduced in the preceding paper. These activity tests prove the high antioxidative and inhibitory capacities of aqueous and ethanolic extracts of propolis in vitro. In the present communication we report on experiments documenting photodynamic quenching properties of these extracts. Using riboflavin, rose bengal or hematoporphyrin as photoactivators and ketomethylthiobutyric acid or crocin as indicators, the protective functions of propolis preparations can be demonstrated. The results indicate that the aqueous extracts are more active than the corresponding ethanolic preparation.

Carotenoids↗
PubMed1997

Micropunctate fluorescein staining of the human corneal surface: microerosions or cystic spaces? A non-contact photomicrographic in vivo study.

PURPOSE: To study in vivo the phenomenon of micropunctate fluorescein staining of the human corneal surface. METHODS: Patients were examined in the slit-lamp and photographed by the means of photomicrography. The staining pattern of fluorescein was compared with that of superimposed rose bengal staining. RESULTS: The staining patterns showed a great correspondence. CONCLUSION: The findings indicate that micropunctate fluorescein staining probably reveals disruptions of intercellular junctions permitting penetration and accumulation of stained fluid beneath diseased cells in situ.

Cell Count↗
PubMed1985

The effects of drugs on tear flow.

Systemic administration of drugs can diminish the tear flow as with timolol and atropine, or can increase the tear production as with bromhexine. Turpentine fumes (100 ppm/30 min or 30 ppm/8 h) have been shown to diminish the break up time (BUT) of tears by diminishing the lipid layer of the precorneal film. Ointment and drugs suspended in oil also diminish BUT, not only do they dry the corneal and conjunctival epithelium (judged by the rose bengal score) but also diminish the outflow as judged by the tear river dye dilution test in both normal people and those with keratoconjunctivitis sicca. Benzalconium chloride in concentrations used as a preservative and cocaine have also been shown to reduce BUT.

Castor Oil↗
PubMed1980

Effect of insulin on the biliary excretion of some organic anions in rats.

In rats insulin enhanced the biliary excretion of rose bengal (50 mg/kg) and bromcresol green (25 mg/kg), and raised the depressed bile flow caused by these organic anions. There was, however, no parallelism between the choleretic effect of insulin and the increase in biliary transport of the two dyes.

Animals↗
PubMed1982

Serological response of cattle after vaccination and challenge with Brucella abortus.

New and currently used serological procedures were evaluated using sera from cattle that were challenged with B. abortus S544 (S544) after vaccination with either B. abortus S19 (S19) or B. abortus 45/20 (S45/20) as calves or adults. In animals vaccinated with S19, titres to the indirect haemolysis test (IHLT) rose more slowly, declined more rapidly and involved fewer animals than did titres to the complement fixation test (CFT). In animals vaccinated with S45/20 the rough antigen complement fixation test (RCFT) showed persistent titres. At slaughter the IHLT and CFT were found to be more specific and more sensitive than the Rose Bengal Plate Test (RBPT) and Serum Agglutination Test (SAT) in the detection of cattle infected with B. abortus.

Agglutination Tests↗
PubMed2005

Photodegradation of hydroxylated N-heteroaromatic derivatives in natural-like aquatic environments. A review of kinetic data of pesticide model compounds.

In the present review, the results published by our group and others related with the study of the kinetic behavior and, in some cases, the mechanism of the dye-promoted photooxygenation of several hydroxypyridines, hydroxyquinolines and hydroxypyrimidines--some of them with the basic molecular structures of known pesticides, and of a few non-hydroxylated model compounds, are compiled and discussed. The main aim was to examine the experimental conditions that maximize the photodegradation efficiencies of all these compounds, under dye-sensitized photooxidation conditions similar to those frequently found in nature, with a natural dye sensitizer such as riboflavin (vitamin B2), a pigment habitually present in natural waters. The usual mechanism of action of this compound is rather complex, in many cases with the concurrent involvement of the oxidative species singlet molecular oxygen (O2(1Deltag)) and superoxide radical anion. In order to simplify the study of the processes, the results found using the synthetic dye Rose Bengal (RB), a sensitizer that generates O2(1Deltag) with high efficiency, are also discussed. RB and similar O2(1Deltag)-generators could be used for the efficient non-natural photodegradation of related pesticides in aqueous solutions under controlled conditions.

Heterocyclic Compounds↗
PubMed1984

An in vivo study of corneal surface morphologic features in patients with keratoconjunctivitis sicca.

We used wide-field color specular microscopy to study the corneal epithelium of 13 normal subjects and 13 patients with keratoconjunctivitis sicca. The frequencies of small, medium, and large cells were different in the two groups, with a shift to small cells in patients with keratoconjunctivitis sicca. Increased uptake of rose bengal dye, filaments, coarse mucus plaques, and pre-exfoliative sheets were also found in the patients with keratoconjunctivitis sicca. These findings suggest accelerated epithelial cell loss from the surface of the eye in keratoconjunctivitis sicca.

Cornea↗
PubMed2003

Lactofen induces isoflavone accumulation and glyceollin elicitation competency in soybean.

Lactofen, the active ingredient of the soybean disease resistance-inducing herbicide, Cobra, induces large accumulations of isoflavone conjugates and aglycones in soybean tissues. The predominant isoflavones induced in cotyledon tissues are daidzein (and its conjugates) and formononetin and glycitein aglycones. The latter two isoflavones are usually present only at very low levels in soybean seedling tissues. In leaves, the predominant lactofen-induced isoflavones are daidzein and formononetin aglycones and the malonyl-glucosyl conjugate of genistein. Isoflavone induction also occurs in cells distal to the point of treatment, but is only weakly systemic. Lactofen also induces elicitation competency, the capacity of soybean cells to accumulate the pterocarpan phytoalexin glyceollin in response to glucan elicitors from the cell wall of the pathogen Phytophthora sojae. Comparison of the activity of a series of diphenyl ether herbicides demonstrated that while all diphenyl ethers tested induced some degree of elicitation competency, only certain ones induced isoflavone accumulation in the absence of glucan elicitor. As a group the diphenyl ethers are thought to inhibit protoporhyrinogen oxidase, eventually leading to singlet oxygen generation. Another singlet oxygen generator, rose bengal, also induced elicitation competency, but little isoflavone accumulation. It is hypothesized that diphenyl ether-induced activated oxygen species mimic some aspects of hypersensitive cell death, which leads to elicitation competency in infected tissues.

Benzopyrans↗
PubMed1985

Effects of unstirred Disse fluid, nonequilibrium binding, and surface-mediated dissociation on hepatic removal of albumin-bound organic anions.

Proceeding from the observation that organic anions bound to albumin have hepatic extraction fractions that are unexpectedly high, we have studied a distributed model that accounts for this phenomenon by invoking sites on the cell surface that catalyze the dissociation of albumin-anion complexes. The present report extends this model to include nonequilibrium binding and rate-limiting diffusion of bound anion to the cell surface. Simulation analysis of the extended model provides an unambiguous basis for interpreting the apparent intrinsic clearance of free anion. The model is fully consistent with the transport data that we obtained with rose bengal [Am. J. Physiol. 248 (Gastrointest. Liver Physiol. 11): G702-G708, 1985] but is suited to estimating only selected components of the unknown parameter vector. Uncertainties inherent in an alternate approach are discussed and illustrated.

Animals↗
PubMed2000

Simple detection method for distinguishing dead and living yeast colonies.

A rapid and simple assay was developed for detection of yeast colonies containing dying or dead cells. Methylene blue, phloxin B, rose bengal and trypan blue at concentrations of 5-10 micromol l(-1) were shown to stain non-viable cells in colonies of Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida albicans and Filobasidium capsuligenum without staining or affecting the viability of living cells of the colonies.

Basidiomycota↗
PubMed1977

An evaluation of 99mTc-labeled hepatobiliary agents.

Scintigraphic imaging of the hepatobiliary system has been significantly improved with the development of 99mTc-labeled compounds. Two of the most promising agents, pyridoxylideneglutamate and HIDA, each formed the basis for the development of a group of structural analogs. Condensation of pyridoxal with leucine and arginine (in place of glutamate) produced pyridoxylideneleucine and pyridoxylidenearginine. Since increasing the molecular weight and the lipid solubility of compounds tends to enhance their biliary excretion, several new IDA derivatives were synthesized by altering the lipophilic substituents on the ring of HIDA. The substitutions included ethyl and ethoxy groups as well as iodine. All compounds were compared with 131I-rose bengal using a baboon model that allowed blood, bile, and urine collection.

Acetanilides↗