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PubMedDate not supplied

[Oxidation of inorganic sulfur compounds by obligatory organotrophic bacteria].

New data obtained by the author and other researchers on two different groups of obligately heterotrophic bacteria capable of inorganic sulfur oxidation are reviewed. Among culturable marine and (halo)alkaliphilic heterotrophs oxidizing sulfur compounds (thiosulfate and, much less actively, elemental sulfur and sulfide) incompletely to tetrathionate, representatives of the gammaproteobacteria, especially from the Halomonas group, dominate. Some of denitrifying species from this group are able to carry out anaerobic oxidation of thiosulfate and sulfide using nitrogen oxides as electron acceptors. Despite the low energy output of the reaction of thiosulfate oxidation to tetrathionate, it can be utilized for ATP synthesis by some tetrathionate-producing heterotrophs; however, this potential is not always realized during their growth. Another group of marine and (halo)alkaliphilic heterotrophic bacteria capable of complete oxidation of sulfur compounds to sulfate mostly includes representatives of the alphaproteobacteria most closely related to nonsulfur purple bacteria. They can oxidize sulfide (polysulfide), thiosulfate, and elemental sulfur via sulfite to sulfate but neither produce nor oxidize tetrathionate. All of the investigated sulfate-forming heterotrophic bacteria belong to lithoheterotrophs, being able to gain additional energy from the oxidation of sulfur compounds during heterotrophic growth on organic substrates. Some doubtful cases of heterotrophic sulfur oxidation described in the literature are also discussed.

Adenosine Triphosphate↗
PubMedDate not supplied

Evaluation of the Reveal quick test for Salmonella detection in raw chicken meat.

Salmonella belongs to the Enterobacteriaceae family, and is the cause of illnesses such as enteric fevers, enteritis and septicemia. Accordingly, a necessity exists of researching and developing new techniques,--which must be sensible, specific, economic and fast--for genus determination; all this related to the culture technique (official technique). In the present work, 80 samples of chicken were analyzed for Salmonella both by the Reveal equipment and by the culture technique with and without a pre-enrichment step (reference technique). Samples were collected in established markets in Netzahualcóyotl City and Chimalhuacán, Estado de México; and analyzed by the culture technique, from which 15 Salmonella strains were isolated. 14 of those strains were obtained when the pre-enrichment step was implemented. Meanwhile, using the Reveal equipment (new technique), the presence of 16 Salmonella strains was identified. The statistical method used, defined as a method of predictive values, calculates the sensitivity and specificity of the Reveal test in relation with the culture technique. It also determines the positive predictive value (PPV), that represents the probability that the microorganism is truly present when the Reveal test scores positive; and the negative predictive value (NPV), that represents the probability that the microorganim is not present when the Reveal test scores negative.

Animals↗
PubMed1989

Chemical modification of chalcone isomerase by mercurials and tetrathionate. Evidence for a single cysteine residue in the active site.

Chalcone isomerase from soybean is inactivated by stoichiometric amounts of p-mercuribenzoate or HgCl2. Spectral titration of the enzyme with p-mercuribenzoate indicates that a single thiol group is modified. Treatment of modified enzyme with KCN or thiols results in a complete restoration of enzyme activity demonstrating that the inactivation is not due to irreversible protein denaturation. A product of the enzymatic reaction, naringenin, provides complete kinetic protection against inactivation by both mercurials. The binding constant (33 microM) for naringenin determined from the concentration dependence of the protection agrees with the inhibition constant (34 microM) for naringenin as a competitive inhibitor of the catalytic reaction. This agreement demonstrates that the observed kinetic protection results from the specific binding of naringenin to the active site. Incubation of native chalcone isomerase with sodium tetrathionate (0.1 M) results in a slow time-dependent loss of enzymatic activity. The inactivation of chalcone isomerase by tetrathionate and N-ethylmaleimide becomes very rapid in the presence of 6 M urea, indicating that the native tertiary structure is responsible for the low reactivity of the enzymatic thiol. The stoichiometric modification of reduced and denatured chalcone isomerase by [3H] N-ethylmaleimide indicates that the enzyme contains only a single cysteine residue and does not contain any disulfides. The evidence presented suggests that the only half-cystine residue in chalcone isomerase is located in the active site and thereby provides the first clue to the location of the active site in chalcone isomerase.

Binding Sites↗
PubMed1987

[Possibility of decreasing the anticomplement activity of human immunoglobulin preparations via chemical modification].

The physicochemical and immunological properties of the experimental batches of the preparations of placental immunoglobulin, obtained by some methods of chemical modification of the molecule of IgG, have been studied. The possibility of abolishing the anticomplement properties of the preparations treated with sulfitolytic agents manufactured in the USSR has been shown. The optimum conditions permitting the production of the preparation with faintly pronounced anticomplement properties and the full monomer structure of its molecule have been established.

Chemical Phenomena↗
PubMed1983

A comparison of two enrichment and two plating media for the isolation of Salmonella sp. from broilers.

Twenty duplicate cloacal swabs and the intestines of 98 broilers were cultured using Rappaport-Vassiliadis and tetrathionate as enrichment broths. These were plated to brilliant green and modified dulcitol brilliant green agars at one, two and seven days. Salmonellae were recovered with greater frequency from tetrathionate plated to modified dulcitol brilliant green than the other combinations.

Agar↗
PubMed1980

Selective effects of organic mercurials on the GTP-regulatory proteins of adenylate cyclase systems.

Treatment of membranes from HeLa cells, rat adipocytes, and rat liver with organic mercurials results in complex effects on adenylate cyclase activity that are not mimicked by the reversible sulfhydryl reagent, tetrathionate. At low concentrations (0.1 mM or less 1 mercurials inactivate the enzyme; inactivation is reversed by the thiol-reducing agent, dithiothreitol. Treatment with higher concentrations of organic mercurials (1 mM and above) results in a time-dependent, irreversible change in the ability of guanine nucleotides and fluoride ion to stimulate adenylate cyclase activity. The irreversible changes are blocked by treatment of membranes with cholera toxin and NAD, suggesting that the GTP-regulatory component is the site of mercurial action. This is further suggested by the lack of irreversible effects of mercurials on adenylate cyclase activity in membranes from mouse lymphoma cells that lack this component. Irreversible effects of mercurials on the adipocyte cyclase system also include enhancement of basal activity and potentiation of the inhibitory effects of GTP on cyclase activity; the latter effects of GTP are mediated through a process independent from that mediating stimulation of activity by GTP. It is concluded that the GTP-regulatory proteins responsible for the modulation of adenylate cyclase activity by hormones and neurotransmitters contain the sites of action of organic mercurials. Their possible mode of action is discussed.

Adenylyl Cyclases↗
PubMed1980

[Comparative efficacies of selenite and tetrathionate broth and Leifson- and Wilson-Blair agar for the isolation of salmonellae (author's transl)].

The statistical interpretation of the isolation of 3,581 Salmonella strains belonging to 30 species or serovars (S) shows that the efficacy of selenite and tetrathionate broth as enrichment media was of similar magnitude for 631 strains for 13 S. The tetrathionate broth was better in the case of 2,520 strains from 11 S and the selenite broth in 430 strains from 6 S including the two pathogenetic most important species S. typhi and S. schottmuelleri. Therefore, this point needs the unconditional use of selenite broth (Table 2). Wilson-Blair agar was more efficient than Leifson agar in the isolation of the most salmonella (Table 2). Also the percentage of suspicious and false-positive colonies on Leifson agar is higher and is due to more expensive work than on Wilson-Blair agar (Table 3).

Agar↗
PubMedDate not supplied

Relative effectiveness of selenite cystine broth, tetrathionate broth, and Rappaport-Vassiliadis medium for the recovery of Salmonella from raw flesh and other highly contaminated foods: precollaborative study.

The effectiveness of selenite cystine (SC) broth, tetrathionate (TT) broth, and Rappaport-Vassiliadis (RV) medium for recovery of Salmonella spp. from 8 highly contaminated foods was determined. RV medium prepared from individual ingredients and incubated at 42 degrees and 43 degrees C was compared with 2 commercial (Difco and Oxoid) media incubated at 42 degrees C. Naturally and artificially contaminated foods were tested under 2 protocols. For Protocol 1, each food was preenriched in the appropriate medium. After incubation, serial 10 fold dilutions of the preenriched foods were inoculated into selective enrichment media and incubated at 35 degrees, 42 degrees, or 43 degrees C. Effectiveness of these conditions was evaluated by most probable number determination of Salmonella spp. recovered. Productivity of selective enrichments did not differ significantly with this protocol, except that with Oxoid RV medium the number of Salmonella cells recovered from most of the foods was significantly reduced. For Protocol 2, twenty 25 g test portions from artificially inoculated foods were examined qualitatively for Salmonella spp. The effectiveness of the broth/temperature combinations was determined by the number of positive tests under each condition. RV medium prepared from individual ingredients and TT broth incubated at 43 degrees C yielded significantly more Salmonella-positive tests from frog legs and lettuce than did SC and TT broths incubated at 35 degrees C or commercial RV medium incubated at 42 degrees C. With pork sausage and ground beef, significantly fewer Salmonella-positive tests were found with Oxoid RV medium incubated at 42 degrees C and SC incubated at 35 degrees C than from other selective enrichments.(ABSTRACT TRUNCATED AT 250 WORDS)

Culture Media↗
PubMed1977

A comparison of tetrathionate broth and Rappaport's medium as enrichment media for Salmonella.

Tetrathionate broth (Müller-Kauffmann) and Rappaport's medium were compared in isolating Salmonella from meat- and bone-meal, receiving waters, sewage, and sludge. The results (Table I) show no difference in isolations from meat- and bone-meal, receiving waters, or sewage, while in studying sludge isolations were significantly less frequent from Rappaport's medium than from tetrathionate broth. The Salmonella positive plates, however, were easier to read when inoculated from Rappaport's medium than from tetrathionate broth.

Bone and Bones↗
PubMedDate not supplied

Relative effectiveness of selenite cystine broth, tetrathionate broth, and rappaport-vassiliadis medium for recovery of Salmonella spp. from raw flesh, highly contaminated foods, and poultry feed: collaborative study.

A collaborative study was performed in 18 laboratories to validate use of Rappaport-Vassiliadis (RV) medium in the standard culture method for recovery of Salmonella spp. from raw, highly contaminated foods and poultry feed. RV medium made from its individual ingredients and incubated at 42 degrees C was compared with selenite cystine (SC) broth incubated at 35 degrees C and tetrathionate (TT) broth incubated at 35 degrees and 43 degrees C for effectiveness in recovery of Salmonella spp. Four artificially contaminated foods (oysters, frog legs, mushrooms, and shrimp) and poultry feed and one naturally contaminated food (chicken) were analyzed. The artificially contaminated foods were inoculated with single serovars of Salmonella at target levels of 0.04 colony-forming units (CFU)/g for the low level and 0.4 CFU/g for the high level. For analysis of 1125 test portions, RV medium (42 degrees C) recovered Salmonella from 409 test portions; TT (43 degrees C), from 368 test portions; TT (35 degrees C), from 310 test portions; and SC (35 degrees C), from 334 test portions. Overall, RV medium was comparable with or better than other selective enrichments for recovery of Salmonella from the foods in this study, except mushrooms. From mushrooms, SC broth (35 degrees C) recovered more positive test portions than did RV medium (42 degrees C) and TT broth (43 degrees C). The method for detection of Salmonella in raw, highly contaminated foods and poultry feed using RV medium has been adopted by AOAC INTERNATIONAL. AOAC Official Method 967.25, Salmonella in Foods, Preparation of Culture Media and Reagents, has been revised to include RV medium, and the applicability of AOAC Official Method 967.26, Salmonella in Foods, Detection, has been restricted to processed foods.

Animal Feed↗
PubMed1976

An improved and simplified radioisotopic assay for the determination of free and esterified carnitine.

The radioisotopic assay for carnitine first described by Cederblad and Lindstedt (Clin. Chim. Acta. 37:235-543, 1972) and modified by Bohmer et al (Clin. Chim. Acta. 57:55-61, 1974) has been improved and simplified. As a result, the assay yields a linear response over a wide range of carnitine concentrations without the need for excessive amounts of labeled acetyl-CoA. In addition, it will measure very small quantities of carnitine even in the presence of excess acylcarnitine. The method allows rapid determination of free and esterified carnitine in small volumes of plasma (50 mul is sufficient) without the need for prior deproteinization of the samples.

Carbon Radioisotopes↗
PubMed1998

Purification and partial characterization of kininogenase activity from Schistosoma mansoni adult worms.

An enzyme presenting kallikrein-like activity (designated sK1) was purified from the supernatant of Schistosoma mansoni adult worm homogenate. The enzyme cleaves bradykinin from purified rat plasma kininogen. Activity was optimal at pH 9.0 and the enzyme showed amidolytic activity, since it hydrolysed the kallikrein synthetic substrate D-Pro-Phe-Arg-p-nitroanilide. The activity of sK1 upon rat plasma kininogen was strongly inhibited by the serine proteinase inhibitors phenylmethanesulfonyl fluoride, aprotinin or soybean trypsin inhibitor, but not by ethylenediaminetetraacetic acid or sodium tetrathionate. The molecular mass of sK1, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, was 66 kDa and the pI value, estimated by analytical chromatofocusing, was 4.2. Physical and chemical properties suggest that sK1 is a serine proteinase of the kallikrein family. Evidence is presented which suggests that sK1 is a component of the tegumental surface of the parasite and the levels of its activity in the male adult worm are approximately 21 times higher than those in the female adult worm. The intravenous injection of 3 micrograms of sK1 into an anaesthetized rat induced a drastic reduction in the arterial blood pressure of the animal. This effect lasted for about 1 min, and was followed by a progressive recovery of the arterial pressure. Neither bradycardia nor cardiac arrhythmias were noticed, suggesting a peripheral vasodilation effect. The presence of sK1 on the surface of adult male worms could play an important role in the wandering capacity of coupled worms into the visceral vasculature of the host.

Animals↗
PubMed1977

Stimulatory and inhibitory effects of sulfhydryl reagent on p-aminohippuric acid transport by isolated renal tubules.

Isolated tubules from rabbit kidney cortex were treated with several different sulfhydryl reagents in an attempt to determine whether sulfhydryl groups are involved in organic acid transport. Disulfide reagents such as sodium tetrathionate and 6,6'-dithionicotinic acid were found to exert a biphasic effect on p-aminohippuric acid transport, i.e. transient stimulation followed by inhibition. In contrast, treatment of tubules with the mercaptide-forming reagent, p-chloromercuribenzoate, caused only inhibition of organic acid transport. Treatment of tubules with reductants such as dithiothreitol or mercaptoethanol blocked the stimulatory effect of tetrathionate without affecting the inhibitory effect of this oxidant. The inhibition caused by p-chloromercuribenzoate, however, was largely reversible when tubules were treated with reductants. The results suggest that the renal organic acid transport system contains sulfhydryl groups and that its activity is increased when some of these groups are oxidized.

Animals↗
PubMed1982

Sulphydryl oxidation in the mechanism of molecular-weight conversion of renin in dog kidney.

1. A high-molecular-weight renin (M(r) 60 000) was formed by the reaction of a low-molecular-weight renin (M(r) 40 000) with a renin-binding substance in canine renal cortical extract in the presence of the sulphydryl (SH) group oxidizing agent potassium tetrathionate; thus the reaction required SH oxidation. 2. Renin extracted from isolate renin granules was adsorbed on to thiopropyl Sepharose 6B, and then liberated with dithiothreitol (50 mmol/1), indicating that it possessed on SH moiety(s). 3. However, the renin was capable of reaction with the renin-binding substance even after its SH moiety (or moieties) was protected with 5,5'- dithiobis-(2-nitrobenzoic acid). 4. The high-molecular-weight renin was converted into the low-molecular-weight renin by incubation (37 degrees C, 15 min) with cytosol (soluble fraction) of renal cortex and liver. Such converting ability was diminished after the cytosol was treated with perchloric acid or potassium tetrathionate. 5. These results suggest that the reaction of renin with the renin-binding substances does not require disulphide bond(s) and that an enzyme-like substance which is sensitive to SH oxidation is involved in the conversion from the high molecular-weight renin into the low-molecular weight renin.

Animals↗