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PubMed1985

Positional specificity of lysosomal acid lipase purified from rabbit liver.

The hydrolysis of tri-, di-, and monooleoylglycerols by highly purified lysosomal acid lipase from rabbit liver (Imanaka, T., et al. (1984) J. Biochem. 96, 1089-1101) was examined. The degradative products were separated by thin layer chromatography on silicic acid impregnated with boric acid. Trioleoylglycerol was hydrolyzed with intermediate accumulation of 1,2(2,3)-dioleoylglycerol and 2-monooleoylglycerol, but no detectable production of the 1,3-isomer. 1,2(2,3)-Dioleoylglycerol was also hydrolyzed with the intermediate accumulation of 2-monooleoylglycerol. The 1(3)-isomer of monooleoylglycerol was hydrolyzed exclusively, with no hydrolysis of the 2-isomer. These results indicate that the enzyme shows preference for 1(3)-ester bonds and that the main lipolytic reaction sequence catalyzed is triacylglycerol---1,2(2,3)-diacylglycerol---2-monoacylglycerol.

Animals↗

PubMed1979

Identification of the C-1-phosphate-binding arginine residue of rabbit-muscle aldolase. Isolation of 1,2-cyclohexanedione-labeled peptide by chemisorption chromatography.

The arginine-specific reagent 1,2-cyclohexanedione reacts selectively with the arginine residue of the C-1-phosphate-binding site of aldolase and inactivates the enzyme. The labeled peptide isolated from tryptic digests of inactivated aldolase was found to correspond to the sequence Leu-43 to Arg-56, the residue modified by cyclohexanedione being Arg-55. This peptide was absent form digests of aldolase treated in the same way but protected from inactivation by the presence of substrate, thus correlating modification of Arg-55 with loss of activity. Selective isolation ofthe peptide containing the modified arginine residue was effected by chemisorption chromatography on boric acid gel, a procedure exploiting the specific interaction of matrix-bound boric acid groups with vicinal cis-hxdroxyl groups of cyclohexanedione-modified arginine side chains.

Animals↗

PubMedDate not supplied

Selection of test chemicals for the ECVAM international validation study on in vitro embryotoxicity tests. European Centre for the Validation of Alternative Methods.

The European Centre for the Validation of Alternative Methods (ECVAM) has sponsored a large international prevalidation and validation study of three embryotoxicity tests, involving embryonic stem cells, limb bud micromass cultures, and post-implantation whole-embryo cultures. The main objective of the study was to assess the performance of these in vitro tests in discriminating between non-embryotoxic, weakly embryotoxic and strongly embryotoxic compounds. An initial part of the study was to select 20 test substances for the formal validation trial, conducted under blind conditions. A database of in vivo and in vitro developmental toxicity test results was complied on 310 chemicals that had been used in previous validation studies, or suggested for such use, or that had good quality "segment II"-type in vivo data, or for which there were human data. From this database, a shortlist of about 30 candidates was constructed. Because the ECVAM study would not include metabolic activation, chemicals known to require activation for their developmental effects were excluded as candidates, although some known stable metabolites were included. Attempts were made: to include substances of diverse mechanism; to avoid overemphasis on pharmaceuticals; to avoid biologically inert substances as non-embryotoxicants; and to make the list different from those used previously. The candidates were of three categories: Class 3, strongly embryotoxic, was defined as developmentally toxic in all species tested, inducing multiple developmental effects, and with a high A/D ratio. Class 1, non-embryotoxic, was defined as not developmentally toxic at maternally toxic exposures, but which may show some minor embryo/fetal toxicity, which cannot be separated from maternal toxicity. Class 2, weakly embryotoxic, were chemicals of intermediate activity. From this candidate list, chemicals of known receptor (androgen, oestrogen, glucocorticoid, aryl hydrocarbon) mechanisms were excluded, on the basis that simple tests for such activity are already available. In addition, chemicals not freely available were excluded, and an emphasis on human data was applied. The final list of 20 chemicals was: Class 3--6-aminonicotinamide, 5-bromo- 2'-deoxyuridine, hydroxyurea, methylmercury chloride, methotrexate, all-trans-retinoic acid; Class 2--boric acid, dimethadione, lithium chloride, methoxyacetic acid, valproic acid (VPA), 2-propyl-4-pentynoic acid (4-yn-VPA), salicylic acid sodium salt; and Class 1--acrylamide, D-(+)-camphor, dimethyl phthalate, diphenhydramine hydrochloride, 2-ethyl-4- methylpentanoic acid (isobutyl-ethyl-VPA), Penicillin G sodium salt, saccharin sodium hydrate.

Animal Testing Alternatives↗

PubMed1983

Positional specificity of hormone-sensitive lipase from rat adipose tissue.

Hormone-sensitive lipase, purified from rat adipose tissue (Fredrikson, G., Strålfors, P., Nilsson, N. O., and Belfrage, P. (1981) J. Biol. Chem. 256, 6311-6320), has been incubated with tri-, di-, and monooleoyl[3H]glycerol, and the acylglycerol reaction products were isolated by thin layer chromatography on silicic acid, impregnated with boric acid. Trioleoylglycerol was hydrolyzed with the intermediate accumulation of monooleoylglycerol, mainly the 2-isomer, and a small amount of 1,2(2,3)-, but no measurable, 1,3-dioleoylglycerol. 2-Monooleoylglycerol was also the major acylglycerol reaction product from 1,2(2,3)-dioleoylglycerol hydrolysis, which occurred at a Vmax of 60% of that with the 1,3-isomer. Part of the 1(3)-monooleoylglycerols found were formed by acyl migration, but 2-ester bond cleavage was directly demonstrated by the use of 1,3-dioleoyl-2-[14C]oleoyl[3H]glycerol as substrate, and by determination of the 14C/3H ratios of the acylglycerol reaction products. Based on the hydrolysis of specific monooleoylglycerol isomers, it was estimated that the 1(3)-ester bonds of the acylglycerols were hydrolyzed 3- to 4-fold faster than the 2-ester bonds. The main lipolytic reaction sequence catalyzed by hormone-sensitive lipase is thus triacylglycerol leads to 1,2(2,3)-diacylglycerol leads to 2-monoacylglycerol. However, the preference for the 1(3)-ester bonds is less marked than that of, e.g. pancreatic and lipoprotein lipase.

Adipose Tissue↗

PubMed1981

[Preparation of anatomic museum specimens while preserving their color and consistency].

Sinitsyn's solution (carbolic acid 9 g, boric acid 15 g, sodium bicarbonate 45 g, distilled water up to 1 litre) is proposed for fixation and storage of museum anatomic preparations which retain their colour and consistence. This method allows further histological examination of museum preparations. The method has been used and approved in the pathology department of the Central District Hospital of the Tymov area.

Color↗

PubMed1995

Competitive inhibitors of free and chitosan-immobilized urease.

The influence of four inhibitors: boric acid, thioglycolic acid, sodium fluoride and acetohydroxamic acid on the activity of urease, both in the native form and immobilized covalently on glutaraldehyde-pretreated chitosan membrane, was studied. Urea hydrolysis was carried out in phosphate buffer, pH 7, at 25 degrees C at urea concentration of 50 mM. The immobilized urease was more resistant than the native one to the action of all the investigated inhibitors, except boric acid. This property of the enzyme offers a possibility of its practical application.

Binding Sites↗

PubMed2006

Removal of lead from aqueous solutions on palm shell activated carbon.

The performance of a commercially available palm shell based activated carbon to remove lead ions from aqueous solutions by adsorption was evaluated. The adsorption experiments were carried out at pH 3.0 and 5.0. The effect of malonic and boric acid presence on the adsorption of lead ions was also studied. Palm shell activated carbon showed high adsorption capacity for lead ions, especially at pH 5 with an ultimate uptake of 95.2mg/g. This high uptake showed palm shell activated carbon as amongst the best adsorbents for lead ions. Boric acid presence did not affect significantly lead uptake, whereas malonic acid decreased it. The diffuse layer surface complexation model was applied to predict the extent of adsorption. The model prediction was found to be in concordance with the experimental values.

Adsorption↗

PubMed1992

Studies on teratological testing using chicken embryos--effects of solvents, injection sites and the age of the embryo.

The purpose of this study was to examine the effects of solvents, injection sites and embryo age when using chicken embryos for teratological testing. The results obtained were as follows: 1) Solvents: distilled water, physiological saline, sesame oil, 25% ethanol, 0.5% carboxymethylcellulose and 0.1% methylcellulose solution were not toxic in Day-4 embryos (eggs incubated for 4 days). 2) With 6-aminonicotinamide, air space injection more effectively induced malformations in chicken embryos. With boric acid, however, yolk sac injection was better. It was shown therefore that the appropriate injection site varied according to the test drug. 3) 6-aminonicotinamide induced characteristic malformations when injected into embryos of various ages ranging from 4 to 13 days of incubation. On the other hand, boric acid was teratogenetic only when injected into Day-3 or Day-4 embryos. It seems, therefore, that the age of the embryo at the time of administration is of critical importance and that the optimum time of administration varies according to the test drug.

6-Aminonicotinamide↗

PubMed1984

The relative biological effectiveness in V79 Chinese hamster cells of the neutron capture reactions in boron and nitrogen.

V79 Chinese hamster cells were irradiated in the presence of different amounts of boric acid with thermal neutrons at the Medical Research Reactor at Brookhaven National Laboratory. From the linear dose-survival curves observed, a D0 value of 66 rad for the 10B(n, alpha) 7Li neutron capture reaction was obtained. No dependence of this value on the concentration of boric acid was found. Comparing this value to the D0 value of 150 rad obtained with 250 kVp X rays between 10 and 0.01% survival, an extrapolated RBE value of 2.3 was calculated. By irradiation of the same line of cells with cold neutrons at the Institut Laue - Langevin , a D0 value for the 14N(n,p)14C reaction of 77 rad was obtained, with a corresponding RBE value of 1.9. Comparison is made with previously published RBE values for the 10B(n, alpha) 7Li reaction.

Animals↗

PubMed2005

Novel immobilization of titanium dioxide (TiO2) on the fluidizing carrier and its application to the degradation of azo-dye.

A photocatalyst was prepared by attaching TiO(2) powder (diameter, 50nm) in the sol state to fluidizing spherical ceramic carriers using a silicon binder. A high initial photocatalytic activity and strong attachment was obtained at a sintering temperature of 500 degrees C. An azo-dye (Orange-G) was used as the test contaminant to examine the photocatalytic effect of the new photocatalyst. The initial pseudo-first order degradation rate constant for Orange-G was 0.11min(-1). However, the photocatalytic activity doubled when boric acid was added to the silicon binder at a B to Si ratio of 106.5%. When sodium ethoxide was added to the silicon binder at a sodium ion to Si ratio of 15.0%, as much as 80% of the initial photocatalytic activity was maintained after the photocatalyst had been agitated at 180rpm for 300min. Adding both boric acid at a B/Si ratio of 106.5% and sodium ethoxide at a Na/Si ratio of 15% increased the photocatalytic activity and stability by three and four times, respectively.

Azo Compounds↗

PubMed1999

The plant cell wall polysaccharide rhamnogalacturonan II self-assembles into a covalently cross-linked dimer.

The location of the 1:2 borate-diol ester cross-link in the dimer of the plant cell wall polysaccharide rhamnogalacturonan II (RG-II) has been determined. The ester cross-links the apiofuranosyl residue of the 2-O-methyl-D-xylose-containing side chains in each of the subunits of the dimer. The apiofuranosyl residue in each of the two aceric acid-containing side chains is not esterified. The site of borate esterification is identical in naturally occurring and in in vitro synthesized dimer. Pb2+, La3+, and Ca2+ increase dimer formation in vitro in a concentration- and pH-dependent manner. Pb2+ is the most effective cation. The dimer accounts for 55% of the RG-II when the monomer (0.5 mM) is treated for 5 min at pH 3.5 with boric acid (1 mM) and Pb2+ (0.5 mM); at pH 5 the rate of conversion is somewhat slower. Hg2+ does not increase the rate of dimer formation. A cation's charge density and its ability to form a coordination complex with RG-II, in addition to steric factors, may regulate the rate and stability of dimer formation in vitro. Our data provide evidence that the structure of RG-II itself determines which apiofuranosyl residues are esterified with borate and that in the presence of boric acid and certain cations, two RG-II monomers self-assemble to form a dimer.

Boric Acids↗

PubMed1976

The granulation of binary mixtures: the effects of the composition of the granulating solution and the initial particle size of one component on granule properties.

The effect of total solvent volume and the presence of dissolved material (other than binder) in the granulating solution, on the properties of granules prepared from lactose: boric acid mixtures has been studied. The total volume of binder solution available to powder mixtures during massing determines the ultimate average size of granules produced. Part-dissolution of powders being granulated contributes significantly to the average granule size by increasing the total solution volume and reducing the amount of powder to be wetted. Although the amount of PVP (binder) dissolved in the granulating solution contributed very little to granule size at the concentration examined, the combined effect of total volume of solution and amount of PVP present in the granulating solution determines granule strength and porosity. The effect of the initial particle size of lactose in a binary mixture with boric acid differs from its effect reported for single component systems.

Boric Acids↗

PubMed2002

Action of boron at the molecular level: effects on transcription and translation in an acellular system.

It has been shown that boric acid has well-defined biological effects such as stimulation of wound healing in vivo, release of growth factors and cytokines, and increase of the extracellular matrice turnover. We examined its action at the molecular level, using cell-free systems of transcription (isolated placenta nuclei) and translation (wheat germ extract). We found that 10 mM boric acid greatly increased RNA synthesis, measured by absorbance at 260 nm (x 6.4) or by [3H]-UTP uptake (x 11). Full-length functional mRNA was produced because proteins of 14-80 kDa were translated. Among these proteins, factors involved in angiogenesis and, subsequently, in wound healing (VEGF and TGFbeta) were identified by slot blot, whereas growth factors such as FGF1 and TNFalpha were not detected. These results demonstrate that boron may contribute to biological cell activities at both the transcription and translation levels. However, the mechanism of action is still not known.

Autoradiography↗

PubMedDate not supplied

Serum and urinary boron levels in rats after single administration of sodium tetraborate.

The pharmacokinetics of boron was studied in rats by administering a 1 ml oral dose of sodium tetraborate solution to several groups of rats (n=20) at eleven different dose levels ranging from 0 to 0.4 mg/100 g body weight as boron. Twenty-four-hour urine samples were collected after boron administration. After 24 h the average urinary recovery rate for this element was 99.6+/-7.9. The relationship between boron dose and excretion was linear (r=0.999) with a regression coefficient of 0.954. This result suggests that the oral bioavailability (F) of boron was complete. Another group of rats (n=10) was given a single oral injection of 2 ml of sodium tetraborate solution containing 0.4 mg of boron/100 g body wt. The serum decay of boron was followed and found to be monophasic. The data were interpreted according to a one-compartment open model. The appropriate pharmacokinetic parameters were estimated as follows: absorption half-life, t1/2a=0.608+/-0.432 h; elimination half-life, t1/2=4.64+/-1.19 h; volume of distribution, Vd = 142.0+/-30.2 ml/100 g body wt.; total clearance, Ctot=0.359+/-0.0285 ml/min per 100 g body wt. The maximum boron concentration in serum after administration (Cmax) was 2.13+/-0.270 mg/l, and the time needed to reach this maximum concentration (Tmax) was 1.76+/-0.887 h. Our results suggest that orally administered boric acid is rapidly and completely absorbed from the gastrointestinal tract into the blood stream. Boric acid in the intravascular space does not have a strong affinity to serum proteins, and rapidly diffuses to the extravascular space in proportion to blood flow without massive accumulation or binding in tissues. The main route of boron excretion from the body is via glomerular filtration. It may be inferred that there is partial tubular resorption at low plasma levels. The animal model is proposed as a useful tool to approach the problem of environmental or industrial exposure to boron or in cases of accidental acute boron intoxication.

Animals↗

PubMed1990

Growth inhibition of Candida albicans and other medically important yeasts by vaginal contraceptive products.

The antifungal effects of two commercially available spermicidal gels (Conceptrol, produced by Ortho Pharmaceutical, Raritan, N.J., and Koromex, produced by Schmid Laboratories, Little Falls, N.J.) as well as pure nonoxynol-9 and boric acid (both components of vaginal contraceptive products) were tested against 50 clinical yeast isolates by the agar dilution method. The formulated products exerted comparable dose-dependent inhibitory effects against all yeasts tested. A 3-fold dilution of the formulated spermicidal products inhibited 90% of the yeast strains tested. To determine if the antifungal effect was due to the spermicidal detergent nonoxynol-9, this compound was tested for antifungal activity but was completely ineffective against Candida albicans in concentrations up to 10%. Boric acid, present in at least one of the products (Koromex), inhibited representative yeasts at a concentration of 0.4%. The relationship of pH and oxygen tension to inhibition by the commercial spermicides was also investigated. The pH values tested ranged from 4 to 7 and had little effect on inhibition; anaerobiosis at pH 7 slightly reduced the inhibitory activity of Conceptrol gel.

Antifungal Agents↗

PubMed1999

The effect of specimen processing delay on borate urine preservation.

AIM: To investigate the effect on urine culture results and their clinical interpretation of delaying the processing of urine samples in which boric acid had been used as a preservative. METHODS: 792 mid-stream specimens of urine from patients attending their general practitioner were received in borate containing plastic jars. The specimens were cultured upon receipt, stored at room temperature, and then recultured the following morning. RESULTS: After overnight delayed culture, the results were altered in 16% of samples and the clinical interpretation of these findings differed in 8% of specimens. In 28 samples (3.5%) the bacterium isolated on initial culture was not the same as that obtained by culture after overnight storage. CONCLUSIONS: Boric acid urine preservation used for overnight delayed processing of samples is associated with a significant alteration in culture results and the attendant clinical interpretation of such specimens. Rapid transportation/processing of urine specimens must remain the optimum procedure.

Bacteria↗

PubMed1975

Topical tetracycline and rifampicin therapy of endemic trachoma in Tunisia.

A controlled chemotherapy trial of trachoma was carried out in a Tunisian oasis among schoolchildren with active disease. We compared 1% tetracycline ointment (79 patients) or 1% rifampicin ointment (76 patients) with 5% boric acid ointment (79 patients). Medications were administered twice daily, six days a week, for ten weeks. Slit-lamp examinations by three ophthalmologists were made independently before treatment as well as five, 19, and 39 weeks after treatment. Bacteriologic cultures were taken during treatment as were smears to detect trachoma agent at each clinical examination. Five weeks after treatment, the intensity of conjunctival disease in the tetracycline and rifampicin groups was reduced significantly when compared with boric acid, but at 19 weeks this suppression was found only in the tetracycline group. Ocular bacterial pathogens were eliminated almost entirely in the two antibiotic groups during treatment. The initial prevalence of trachoma (29to 31%) was significantly reduced in the two antibiotic-treated groups at five weeks and 19 weeks after treatment. The prevalence of trachoma was equally low (7%) in all three groups following retreatment with tetracycline. Although both antibiotics were effective, rifampicin offered no advantage over tetracycline in this trial. Recurrent disease in this school-based treatment study probably was due to reinfection from younger siblings at home. While systematic, community-wide, antibiotic treatment programs are not always possible in countries where trachoma is endemic, limited antibiotic therapy programs should be continued in these areas to reduce the intensity and prevalence of trachoma, even though the disease cannot be eradicated.

Administration, Topical↗

PubMed2004

Assay of phenolic compounds in red wine by on-line combination of capillary isotachophoresis with capillary zone electrophoresis.

The on-line combination of capillary zone electrophoresis (CZE) with capillary isotachophoresis (ITP) increases significantly the separation capability and sensitivity of capillary electrophoresis. This technique was used for separation and quantification of fourteen selected natural constituents in red wine belonging to flavonoids and phenolic acids. The leading electrolyte (LE) in the ITP pre-separation step was 10 mM HCl of pH* 7.2 with Tris as counterion, the terminating electrolyte (TE) was 50 mM boric acid of pH* 8.2 (adjusted with barium hydroxide). The background electrolyte in the electrophoretic step contained 25 mM beta-hydroxy-4-morpholinopropanesulfonic acid (MOPSO), 50 mM Tris, 15 mM boric acid and 5 mM beta-cyclodextrin of pH* 8.5. The content of methanol in all electrolytes was 20% (v/v). For exact timing of the transfer of isotachophoretically stacked analyte zones into the CZE column and for the control of the residual amount of leading and terminating ITP electrolytes picric acid was used as coloured marker. The R.S.D. values (n = 6) ranged between approximately 0.1% (for 0.25 microg ml(-1) rutin) and approximately 11% (for 0.25 microg ml(-1) of quercitrin). Detection limits were 30 ng mi(-1) for phenolic acids, quercitrin and rutin, 100 ng ml(-1) for quercetin, kaempferol and epicatechin and 250 ng ml(-1) for catechin. A single analysis took 45 min.

Electrophoresis↗