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PubMed1992

Inhibitory effect of diet related sulphydryl compounds on the formation of carcinogenic nitrosamines.

N-Nitroso compounds (NOCs) are known to be strong carcinogens in various animals including primates (Preussman and Stewart, (1984) N-Nitroso Compounds). Human exposure to these compounds can be by ingestion or inhalation of preformed NOCs or by endogenous nitrosation from naturally occurring precursors (Bartsch and Montesano, Carcinogenesis, 5 (1984) 1381-1393; Tannebaum (1979) Naturally Occuring Carcinogens, Mutagens and Modulators of Carcinogenesis; Shephard et al., Food Chem. Toxicol., 25 (1987) 91-108). Several factors present in the diet can modify levels of endogenously formed nitrosamines by acting as catalysts or inhibitors. Compounds in the human diet that alter nitrosamine formation would thus play an important role in carcinogenesis study. Earlier researchers have reported the nitrite scavenging nature of sulphydryl compounds (Williams, Chem. Soc. Rev., 15 (1983) 171-196). We therefore studied the modifying effect of sulphydryl compounds viz., cysteine (CE), cystine (CI), glutathione (GU), cysteamine (CEA), cystamine (CEI), cysteic acid (CIA) and thioglycolic acid (TGA) on the nitrosation of model amines viz., pyrrolidine (PYR), piperidine (NPIP) and morpholine (NMOR). Many of these compounds are present in the food we consume. The present work also describes the inhibitory effect of onion and garlic juices on the nitrosation reactions. Both onion and garlic are known to contain sulphur compounds (Block, Sci. Am., 252 (1985) 114-119). Most of these compounds behave as antinitrosating agents and their inhibitory activity towards formation of carcinogenic nitrosamines, under different conditions is described.

Allium↗
PubMed1999

Metabolic fate of a new histamine H2-receptor antagonist, Z-300, in rat.

1. The metabolisms of (N-[3-[3-(piperidinomethyl)-phenoxy]-propyl]-2-(2-hydroxyethyl-1-t hio) acetamide.2-(4-hydroxy benzoyl) benzoate) (Z-300) in rat have been studied. 2. Five metabolites were identified, namely as sulphoxide (SO), sulphone (SO2), phenol (PH), propionic acid (PA) and thioglycolic acid (TH) derivatives. Furthermore, two metabolites, M1 and M2, were proposed as PH conjugated to sulphate and glucuronic acid respectively. 3. There were several metabolites in the plasma samples after oral administration of 14C-Z-300. The main metabolites were PH (mainly existing as the conjugates), PA and SO, and Z-300 was present as <10% of plasma radioactivity. SO2 and TH were barely detected in plasma. In the urine, the composition of metabolites was similar to that in the plasma. In the bile, the main metabolites were PH (mainly existing as the conjugates) and SO, and very little Z-300 was detected. In the faeces, the main compounds were Z-300 and TH, and very little SO. 4. During in vitro metabolism experiments, Z-300 was metabolized mainly in the liver, and a little in the kidney and lung. PH or its conjugates were produced little on the in vitro metabolism; this was different from that found in the in vivo experiment. The metabolism of Z-300 to SO appeared to be catalysed by cytochrome P450 rather than the flavin-containing monooxygenase. Both hepatic clearance calculated from the in vitro metabolism experiment (28.9 ml/min/kg) and from the liver perfusion metabolism experiment (33.2 ml/min/kg) were lower than the total clearance from the in vivo experiment (119 ml/min/kg). 5. After administration of 14C-SO into the caecum of rat, SO was converted to Z-300 and excreted in the faeces. 14C-SO was reduced by incubation for 4 h within the caecal content of rat under an anaerobic condition in vitro. The results suggest that SO was reduced to Z-300 by gut flora in the lower intestine.

Acetamides↗
PubMed1990

Further study on gas phase acid hydrolysis of protein: improvement of recoveries for tryptophan, tyrosine, and methionine.

A novel method for vapor phase acid hydrolysis of protein suitable for quantitative analysis of tryptophan is presented. The hydrolysis is carried out in vapor of a mixture made of 7 M HCl, 10% trifluoroacetic acid, and 20% thioglycolic acid in the presence of indole. Reasonably good recoveries of common amino acids, including tryptophan (above 75%), were achieved.

Hydrochloric Acid↗
PubMed1976

Synergistic growth promoting action of L-cysteine and nitrogen upon Hymenolepis diminuta cysticercoids in vitro.

Development in vitro of cysticercoids of the cestode Hymenolepis diminuta in the presence of L-cysteine proceeded twice as rapidly under 100% nitrogen as it did with air as the gas phase. No growth was obtained with the following: D-cysteine, L-cysteine methyl ester, S-aminoethyl cysteine, L-cystine, glutathione (reduced), L-methionine, D-pantothenic acid, taurine, or thioglycolic acid; limited growth only was obtained with ascorbic acid and dithiothreitol. Homocysteine or coenzyme A was as effective as L-cysteine in stimulating the complete development of oncospheres to cysticercoids. Experiments with 14C-L-cysteine indicated that L-cysteine was perhaps incorporated into the organisms.

Animals↗
PubMed1984

Equivalence of conventional anti-picryl T suppressor factor in the contact sensitivity system and monoclonal anti-NP TsF3: their final non-specific effect via the T acceptor cell.

There is considerable confusion over whether the antigen-specific T suppressor factors (TsF) described by different authors are indeed equivalent. This paper investigates whether monoclonal TsF3, obtained from hybridomas derived from mice injected subcutaneously with NP derived spleen cells, is functionally equivalent to the conventional T suppressor factor, produced by mice injected intravenously with chemically reactive, water soluble haptene (picrylsulphonic acid and oxazolone thioglycolic acid). Comparison of monoclonal anti-NP TsF3 with conventional anti-picryl and anti-oxazolone T suppressor factor showed that both armed the non-specific T acceptor cell (Tacc) which was sensitive to cyclophosphamide and adult thymectomy. Moreover, non-specific inhibitor (nsINH) of the transfer of contact sensitivity was released when antigen, together with major histocompatibility complex products (MHC), reacted with conventional or monoclonal TsF on the surface of the non-specific T acceptor cell. The interaction of monoclonal TsF3 with antigen, which led to the release of NsINH, required the presence of MHC and was I-J restricted. However, there was no Igh-1 restriction. The equivalence of conventional anti-picryl and anti-oxazolone TsF has been demonstrated by arming the Tacc with a mixture of these two suppressor factors, and then triggering the release of nsINH with the mixed haptene 'picryl-oxazolone-lysine' which crosslinks separate molecules of TsF. A similar equivalence of conventional anti-oxazolone TsF and monoclonal anti-NP TsF3 was demonstrated using the mixed hapten 'NP-oxazolone-lysine' to trigger the release of nsINH. It was concluded that monoclonal TsF3 and conventional TsF were equivalent, and that both had an indirect mode of action through the non-specific T acceptor cell which led to the production of non-specific inhibitor.

Animals↗
PubMed1982

Inhibition of intercellular communication in Chinese hamster V79 cells by teleocidin.

Teleocidin, a mixture of teleocidin A and teleocidin B, was found to block metabolic cooperation between the 6-thioguanine-resistant and the 6-thioguanine-sensitive cells in the Chinese hamster V79 cell system. A teleocidin B preparation containing two isomers exerted the same effect. The dose-response curves of these two compounds were, in general, similar to that of 12-O-tetradecanoyl-phorbol-13-acetate, a powerful mouse skin tumor promoter. Upon hydrolysis with 6M hydrochloric acid containing 4% thioglycolic acid, teleocidin lost most of its ability to block metabolic cooperation. This was probably caused by the conformational change resulting from the rupture of the nine-membered lactam ring of teleocidin.

Alkaloids↗
PubMed1994

Synthesis and antibacterial activity of thioglycolic amino acid derivatives and dipeptides containing the 2-methyl-3,4-dihydroquinazolin-4-one moiety.

3-(2'-Chloroethyl)-2-methyl-3,4-dihydroquinazolin-4-one (I) was reacted with sodio (sodium thioglycolate) in dry dioxane and yielded compound II. By using thionyl chloride, this compound was converted to the corresponding acid chloride (III). The prepared acyl chloride (III) was allowed to interact with different alpha-amino acids such as Gly, L-Ala, L-B-Phe, DL-Asp, L-Glu, L-Thr and L-Val to give new amino acid derivatives (IVa-g). A selected C-terminal derivative of glycine (IVa) was converted into acid chloride (V). The acid chloride formed was reacted with L-Ala, L-B-Phe, DL-Asp, L-Glu, L-Thr and L-Val and yielded the new dipeptides VIa-f. The structures of the synthesized compounds were elucidated by elemental analysis and IR spectra. The prepared peptides were tested for their antimicrobial activities by comparison with tetra-cycline as a reference compound.

Amino Acid Sequence↗
PubMed1986

Detection of sperm histone diversity among vertebrates by alkaline fast green staining.

Testis sections from fifteen species from six classes of vertebrates were stained with alkaline fast green (AFG) to correlate staining differences with the known biochemical diversity of histones in the spermatozoa. After trichloroacetic acid (TCA) hydrolysis the sperm of some species known to contain sperm-specific histones did not stain. This correlation held if fixation in neutral buffered formalin was limited to 3 to 6 hr and hydrolysis was done at 90 C. The species whose sperm did stain after TCA hydrolysis could be divided into three groups. In some species the sperm no longer stained if, after TCA, the sections were treated with thioglycollic acid. These sperm contained basic proteins that were rich in cysteine. In turn, the group of species whose sperm continued to stain after TCA and thioglycollic acid treatments could be subdivided. The sperm of some were stained specifically without DNA hydrolysis if the AFG was made up with sodium chloride. These sperm contained sperm-specific histones. In other species the sperm did not stain under these conditions, and these sperm had a basic protein complement similar to that found in somatic cell nuclei. These correlations suggest that AFG staining can be used to detect sperm histone diversity in a wide range of organisms.

Animals↗
PubMed1981

Spectrophotometric study of several sensitive reagents for serum iron.

A comparison of three sensitive ligands for iron is described. All show varying degrees of enhancement of values by copper, an element that is the primary interference encountered in serum assays for iron. Two of three tested reagents, 2,4-bis(5,6-diphenyl-1,2,4-triazin-3-yl) pyridine tetrasulfonate and Ferene S are not current clinical chemistry choices whereas ferrozine is widely used. The described study presents spectral characterization of the copper interference with all three ligands. The virtual complete removal of this interference, by the masking actions of either thioglycolic acid, neocuproine or thiourea, is also described . Evidence will be presented that contradicts a previously proposed mechanism for the action of thioglycolic acid which suggests that copper is prevented from dissociating from its protein-binding site by this compound. The preparation of a protein-free filtrate as the matrix in which to generate the color reaction is described, and alternative procedures discussed in brief.

Benzenesulfonates↗
PubMed2004

Synthesis and characterization of thiomers of polyaspartamide type.

Synthesis of poly[alpha,beta-(N-2-hydroxyethyl-DL-aspartamide)]-thioglycolic acid (PHEA-TGA) conjugate as a new polyaspartamide thiomer is described. The parent polymer PHEA is chemically modified by introducing sulphydryl-bearing compound thioglycolic acid. By varying the reaction conditions several batches of PHEA-TGA conjugates were prepared and analyzed. Tensile studies revealed that total work of adhesion of PHEA-TGA increased more than twice compared to the unmodified polymer. Microparticles prepared from the thiolated polymer preserved its bioadhesive properties.

Chemistry, Pharmaceutical↗
PubMed2002

Protective actions of rat gastric epithelial E-cadherin expression against epithelial barrier dysfunctions induced by chemical hypoxia-reoxygenation in vitro.

BACKGROUND AND AIM: E-cadherin expressed on gastric epithelium is reported to form adherence junctions and stabilize barrier functions. While hypoxia-reoxygenation is well known to cause gastric mucosal injury during reoxygenation, gastric E-cadherin actions against this stress remain unclear. In this study, using the oxygen depleting agent thioglycolic acid we examined whether E-cadherin expressed on rat cultured gastric epithelial cells has protective actions against epithelial barrier dysfunction induced by chemical hypoxia-reoxygenation. METHODS: Chemical hypoxia was induced by incubating cells with 5 mm thioglycolic acid in glucose free medium for 60 min. Cells were then reoxygenated for 240 min by changing to normal medium. The expression of E-cadherin on the cell surface was measured with an enzyme immunoassay, and epithelial permeability was determined by the diffusion rate of FITC-dextran through the cell layer. RESULTS: E-cadherin expression increased during the 60 min hypoxic period, accompanied by activation of protein kinase C, protein kinase G and protein kinase A. The increased expression significantly diminished, but was considerably higher than the control values during reoxygenation for 180 min, which was partially due to generation of reactive oxygen species but not to activation of protein kinase. Conversely, epithelial permeability was stabilized during hypoxia, but increased only for 30 min of reoxygenation, probably due to generation of reactive oxygen species. Epithelial permeability during hypoxia was elevated by a combination of all the protein kinase inhibitors. CONCLUSION: An increase in the expression of E-cadherin during hypoxia through the activation of the kinases is likely to stabilize epithelial barrier functions. The reactive oxygen species generated during 30 min reoxygenation increased the molecular expression of E-cadherin less than during hypoxic stress. The transient break in the barrier functions caused by reactive oxygen species during reoxygenation appears to overcome the reactive oxygen species mediated cytoprotective action increasing E-cadherin expression.

Animals↗
PubMedDate not supplied

[Semiautomatic procedure for determining urine iron in subjects treated with deferoxamine B].

A semiautomatic method for the determination of urine iron during treatment with deferoxamine B has been evaluated: samples were diluted 1:10 with a TCA 10% and thioglycolic acid 1.1% solution and processed after centrifugation by the aca III discrete clinical analyzer Du Pont. In this way an overestimation of values depending on the turbidity caused by proteins is avoided and the bad smell is limited thanks to the very low concentration of the thioglycolic acid solution. A good correlation with the atomic absorption spectrophotometry, specially for values less than or equal to 20 mg/l, was observed examining urine samples of 150 patients treated with deferoxamine B.

Deferoxamine↗
PubMed1998

Ultrastructure of human scalp hair shafts as revealed by freeze-substitution fixation.

Human scalp hair is important as a diagnostic clue to many diseases, in medical jurisprudential investigations, and also as a subject of cosmetic treatments. While many ultrastructural studies of the human hair root including the hair follicle have been reported, few studies have been done on the human hair shaft. We report here the ultrastructure of human scalp hair shafts prepared by a rapid-freezing technique followed by freeze-substitution fixation that allows the observation of fine cell structures. Healthy scalp hair shafts from Japanese females 12-13 years of age were rapid-frozen and then freeze-substituted in OsO4-acetone. In addition, this technique was applied to the study of some changes of the hair shafts (i.e., hair damaged by thioglycolic acid cold permanent waving and white hair). By this method, the hair shaft was rapid-frozen throughout without appreciable ice damage although the hair shaft was nearly 100 microm in diameter. The rapid-freezing technique resulted in excellent preservation of the ultrastructure of the hair shafts: lamellar structures in the cuticle and fine fibrous ultrastructures in the cortex were observed without chemical treatments. Thioglycolic acid treatment affected the ultrastructure of both the cuticle and the cortex. Except for the absence of melanin granules, no significant differences in the ultrastructure were observed between white hair and black hair. The rapid-freezing technique followed by freeze-substitution fixation appears to be the most reliable approach for the morphological evaluation of fully keratinized cells and tissues.

Adolescent↗
PubMed1991

Hyperdiploidy and trisomy of chromosome 15 in peritoneal macrophages of hyperimmune, older Swiss mice.

Chromosome analysis was carried out in resident and exudate peritoneal macrophages and, also, in bone marrow cells of groups of mice either immunized with ovalbumin in complete Freund's adjuvant and challenged with the antigen, or stimulated with the irritant thioglycollic acid. Labeling of the phagocytic cells with colloidal carbon showed that dividing cells in the peritoneal cavity of experimental mice are resident macrophages. Also shown was an increase in number of hyperdiploid metaphases in hyperimmune, older mice but not in the young ones. Statistical analysis showed these differences to be significant. G-banding of hyperdiploid cells of hyperimmune older mice showed trisomy of chromosome 15 in several metaphases analyzed. The absence of hyperdiploid metaphases in the bone marrow cells of hyperimmune mice and in exudate macrophages of mice that received the irritant thioglycollic acid suggests that hyperdiploidy occurs in resident macrophages in the peritoneal cavity but not in their precursors in the bone marrow. These results raise some questions such as, hyperimmune older mice resident macrophages being prone to hyperdiploidy and trisomy of chromosome 15.

Aging↗
PubMed2002

Continuous production of L-phenylalanine by Rhodotorula glutinis immobilized cells using a column reactor.

Studies have been conducted on L-phenylalanine (L-Phe) production and phenylalanine ammonia lyase (PAL) stabilization in the presence of several optimum effectors and reducing agents under bioconversion of transcinnamic acid (t-CA) conditions during repeated batch operations. L-Phe production was maximized and reuseability of PAL catalyst was extended to eight consecutive cycles (repeated batches) in the presence of optimum effectors (glutamic acid, polyethylene glycol and glycerol), thioglycolic acid and sparging with nitrogen gas. These best optimum bioconversion conditions desensitize the PAL catalyst to substantially elevated higher substrate t-CA concentrations and inhibit inactivation of PAL enzyme over longer reaction periods compared to the control. The fed batch mode operation of bioconversion of total t-CA (300 mM) to L-Phe was superior (65.2%, conversion), comparing with conventional batch and repeated batch (58.4%, conversion) operations after 120 h. Gamma irradiation process was employed to polymerize and crosslink polyvinyl alcohol (PVA) with N,N'-methylene-bisacrylamide (BIS) agent. The use of immobilized PAL biocatalyst containing cells in PVA-BIS copolymer gel carrier produced by radiation polymerization is obviously advantageous with regards to the yield of L-Phe which was increased in average 1.2-fold when compare to those obtained with free cells during optimum bioconversion process. When comparing the magnitudes of gamma irradiation effects on immobilized entrapped yeast cells in PVA-BIS copolymer gel carrier using scanning electron microscopy it was show that yeast cells were protected and capable to overcome these conditions and had normal shape and other features as free (unirradiated) intact yeast cells. Optimum conditions for continuous production of L-Phe by PVA-BIS copolymer carrier entrapped yeast cells in a packed bed column reactor in recycle fed-batch mode were investigated. Under these optimum conditions L-Phe accumulated to concentration 240.1 mM represts a total conversion yield of 80% (w/w) from (300 mM) t-CA after 84 h of reaction process, which was higher than that obtained after 120 h of reaction, 65.2% (w/w) from (300 mM) t-CA with free cells in fed-batch mode. The results also demonstrated that during about 4 weeks of repeated continuous recycle fed batch mode experiments (using immobilized cells in packed bed reactor), the final production of L-Phe concentrations decreased gradually in eight consecutive runs with no sign of breakage or disintegration of the carrier gel beads.

Acrylamides↗
PubMed1986

Purification and characterization of phosphodiesterase from the venom of Trimeresurus mucrosquamatus.

Phosphodiesterase was isolated from the venom of Trimeresurus mucrosquamatus from Taiwan using gel filtration on a Sephadex G-100 column, followed by anion or cation exchange chromatography. Phosphodiesterase was homogeneous as established by a single band on acrylamide gel electrophoresis and immunodiffusion. Phosphodiesterase activity was inhibited by ethylenediamine tetraacetic acid (EDTA), o-phenanthroline, thioglycolic acid or p-chloromercuribenzoate (PCMB) but not by soybean trypsin inhibitor (SBTI) or benzamidine. The molecular weight of this enzyme was determined to be approximately 140,000 and the isoelectric point was found to be pH 7.4 by isoelectric focusing with carrier ampholyte. The Michaelis constant (Km) of this enzyme for p-nitrophenyl thymidine-5'-phosphate and inhibition constant (Ki) for PCMB were found to be 5.6 X 10(-3) and 7.6 X 10(-4) M, respectively.

Amino Acids↗