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A degraded antigen containing a large amount of thiobarbiturate-reactive material, and distinguishable from the acetic acid-degraded polysaccharide antigen, was obtained by phenol extraction of a Boivin antigen.
The amount of thiobarbiturate-reacting material in 51 strains of bacteria and three yeasts was determined. Reactive material was found to be present in all of the gram-negative bacteria examined. It was assumed that the reactive material in this case was primarily 2-keto-3-deoxyoctonate (KDO), an eight-carbon sugar acid which is usually associated with the cell wall lipolysaccharide of members of the Salmonella-Escherichia group. Very little reactive material could be detected in the gram-positive species and yeasts that were examined. When expressed as per cent dry weight, the gram-negative bacteria exhibited about eight times more reactive material than the gram-positive species. It is suggested that the small amount of reactive material detected in gram-positive cells and yeasts is due to compounds other than KDO.
Several 1-(o-aryl)barbituric and -2-thiobarbituric acid derivatives were proven to be chiral in their conformational ground states due to the hindered rotation about the C(aryl)-N(1) bond, by observation of diastereotopic groups (H or CH3) at 5-position of the heteroring by 1H and 13C NMR. Some of the enantiomers were semipreparatively enriched by liquid chromatography on triacetylcellulose or on cellulose tris-(3,5-dimethyl)-phenylcarbamate (chiralcel OD-H). Circular dichroism spectra of the enriched enantiomers have been examined with reference to their stereostructures.
Thiobarbituric acid reacting (TBAR) substances were measured in washed platelets before and after ingesting 120 mg of standardized Gingko biloba extract daily for 3 months, in both normocholesterolemic (total cholesterol, 160 +/- 27 mg/dl; age 40 +/- 13 years; n = 18) and hypercholesterolemic subjects (total cholesterol, 229 +/- 35; age, 45 +/- 8 years, n = 12). Gingko biloba extract significantly reduced cellular content of TBAR substances; 42 +/- 21 vs. 28 +/- 16 pmol/10(7 platelets (p < 0.0025) and 50 +/- 17 vs. 29 +/- 13 pmol/10(7) platelets (P < 0.004), for the normo- and hypercholemic subjects, respectively. In conclusion, Gingko biloba extract is a potent antioxidant for both groups, reducing TBAR substances possibly by inhibiting platelet COX-1 isoform activity.
The UV absorption method and the thiobarbituric acid (TBA) test for oxidation of an aqueous suspension of linoleate were compared. The absorption method depends on the formation of hydroperoxides having conjugated double bonds that absorb strongly at 233 nm. The absorption at 233 nm increased markedly during oxidation of linoleate catalyzed by either ascorbic acid or cupric ions. The concentration of ascorbic acid in the reaction mixture was also measured by UV absorption at 265 nm and pH 7.0. Color development in the TBA test also increased markedly with the extent of oxidation of linoleate. When ascorbic acid was the catalyst, UV absorption detected early stages of oxidation with greater sensitivity than the TBA test. The reverse was true when Cu(++) was the catalyst. In general, the relation between the two procedures will depend on whether copper is present when the TBA test is made.
Constantly coupled ventricular bigeminy in dogs can be elicited by intravenous boluses of thiamylal sodium. Properties of the bigeminal rhythm are similar to those produced by halothane or cyclopropane inhalation anesthetic-epinephrine-induced dysrhythmias. The mechanism responsible for the initiation of ventricular bigeminy, and perhaps most dysrhythmias in the dog during thiobarbiturate anesthesia, appears to be an imbalance between parasympathetic and sympathetic efferent activity. Moderate increases in arterial blood pressure and atrial rate augment the tendency for dysrhythmia production. Atropine was effective in abolishing ventricular bigeminy in most cases through overdrive suppression. Propranolol appeared to abolish ventricular bigeminal rhythms by suppression of sympathetic efferent activity without causing noticeable changes in arterial blood pressure.
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The reactions of 1, 2-dihydro-2-thioxo-4, 6(1H, 5H)pyrimidinedione (1) with some pi-deficients have led to the formation of unexpected heterocyclic products such as anilinomethylenethioxopyrimidinedione, 2, 2'-bis(pyrimidinecarbothioamide), allylthioxopyrimidinecarbothioamide, indenopyranopyrimidine and benzofuropyrimidine derivatives. A possible mechanism for the formation of these products is discussed, and the biological activity is determined.
Rancidity of frozen fish (Baltic cod and herring, mackerel, horse mackerel and hake) was determined by means of TBA value, organoleptical scoring and peroxide value. The correlation between the rancid odour sensory assessment and TBA test results proved insignificant (r = 0.53). Model experiment was undertaken in which promine D with addition of papain was incubated at 50 degrees C over 44 h. It was shown that as accumulation of protein hydrolysis products proceeded the increase of TBA value has taken place without development of rancid odour and with peroxide content below sensibility of sulphocyanide method. With regard to fish, therefore, it seems that the TBA test applied by means of techniques in which the reaction with TBA proceeds in the presence of interfering substances should be treated as a "freshness test" rather than a strictly rancidity one.
Several methods for the quantitative analysis of sialic acids in glycoconjugates require that the sialic acid glycosidic bond be cleaved prior to assay. The conventional (L. Svennerholm, (1958) Acta Chem. Scand. 12, 547-554) procedure for the hydrolysis of complex carbohydrates such as gangliosides employs 0.1 n H+ at 80 degrees C for 60 min. Under these conditions, we find that the monosialoganglioside (GM1) yields less than 50% of the total sialic acid. However, 90% recovery of sialic acid was achieved by supplementing the hydrolysis mixture with 0.2% sodium dodecylsulfate (SDS) and increasing the temperature to 85 degrees C. During hydrolysis under these conditions, N-acetylneuraminic acid (NAN) is degraded at about 7% per hour. If the analytical values for GM1 are corrected for degradation, the recovery of NAN is essentially quantitative.
The relationship between free radicals reactions and the cell detoxifying system was investigated during the development of brain edema following a cryogenic lesion in the rabbit cerebral cortex. The amount of TBA-reactive material present six hours after freezing was less than in the controls, then increased at 48 and 96 hours. The activity of superoxide dismutase (SOD) decreased 6 hours post-injury; at the same time, we observed a stimulation of catalase activity. The glutathione peroxidase activity (GSH-Px) rose 96 hours post-lesion. The decrease of TBA-reactive products could result from an elimination rate that exceeds generation.
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