Effects of equinatoxins in vivo. Possible role of degranulation of thrombocytes and granulocytes.
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Animals↗
Biomedical subjects
T Turk
Publications and source records attributed to T Turk.
Oxidation of dithiothreitol during turnover of nitric oxide reductase: evidence for generation of nitroxyl with the enzyme from Paracoccus denitrificans.
The stoichiometric relationship between thiol oxidized and NO reduced was studied for the reaction catalyzed by nitric oxide reductase from Paracoccus denitrificans. The reaction systems consisted of dithiothreitol, ascorbate, phenazine methosulfate, enzyme and NO, or that system minus ascorbate. The mole ratio of thiol groups oxidized to NO reduced was observed to be 2.3 to 1.5 over a range of NO from 0.09 to 0.35 mumol. A ratio of 1.0 was expected for the simple reduction of NO by 1-electron to N2O. The oxidation of additional thiol is attributed to the trapping of nitrosyl hydride (nitroxyl, NO/NOH) by thiol.
Dithiothreitol↗
The role of tryptophan in structural and functional properties of equinatoxin II.
A pore-forming, cytolytic and lethal polypeptide, equinatoxin II, from the sea anemone Actinia equina, was subjected to oxidation with N-bromosuccinimide to study the role of five present tryptophan residues in structure-function relationships. In the folded toxin molecule, 1-2 tryptophan residues were readily susceptible to oxidation with N-bromosuccinimide, whereas modification of a single residue resulted in complete impairment of the toxin lethal and hemolytic activities as well as the ability of an oxidized toxin to precipitate with serum lipoproteins. CD and fluorescence spectra indicated a slight alteration of a toxin secondary structure following N-bromosuccinimide treatment. Incubation with sphingomyelin of the toxin prior to oxidation did not prevent subsequent modification with N-bromosuccinimide and loss of its activities, indicating that the modified tryptophan residue is not directly involved in toxin binding and insertion into lipid membranes. It was concluded that the modified tryptophan residue is essential for the structure of equinatoxin II.
Animals↗
The role of lysine, histidine and carboxyl residues in biological activity of equinatoxin II, a pore forming polypeptide from the sea anemone Actinia equina L.
Equinatoxin II, a pore forming polypeptide from the sea anemone Actinia equina L. was subjected to chemical modifications with group specific reagents. Lysine residues were modified with pyridoxal-5'-phosphate, histidine residues with diethyl pyrocarbonate and carboxyl groups with the use of a water soluble carbodiimide. Modification of charged residues had no significant influence on the toxin interaction with serum lipoproteins. Lysine 5'-phosphopyridoxylated and histidine carbethoxylated derivatives of the toxin retained lethal and hemolytic activities, but the pH profile of hemolytic activity of 5'-phospho-pyridoxylequinatoxin II was markedly altered. Modification of the toxin carboxyl groups impaired both hemolytic and lethal activities, the latter, however, to the greater extent.
Animals↗
Nitric oxide reductase. Purification from Paracoccus denitrificans with use of a single column and some characteristics.
Nitric oxide reductase was purified from Paracoccus denitrificans very nearly to homogeneity by a simple method that involved the use of octyl glucoside to solubilize the enzyme from membranes and required a single hydroxyapatite column. The enzyme had specific activities of about 10 mumol NO reduced x min-1 x mg-1 at pH 6.5 in an amperometric assay system using phenazine methosulfate/ascorbate as the reducing agent and about 22 mumol NO reduced x min-1 x mg-1 at pH 5.0, which is the optimum pH. These values are based on average rates over kinetically complex progress curves and would be about three times greater if based on maximum rate values. The enzyme appeared to be reversibly inhibited by NOaq and to have a Km too low (probably less than or equal to 1 microM) to measure reliably by the amperometric method. The effective second-order rate constant of the enzyme lay within 1 to 2 orders of magnitude of the diffusion controlled limit. The enzyme was composed of a tight complex of two cytochromes: a cytochrome c (Mr = 17,500) and a cytochrome b (Mr = 38,000). The mole ratios of cytochrome c to cytochrome b and Mr 17,500 peptide to Mr 38,000 peptide were both about 1.7, and the heme content was about 3 mol/73,000 g (38,000 + 2(17,500)). Each subunit therefore contained only one heme group. The Mr 38,000 peptide aggregated when heated in the sample buffer used for sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In addition to the ascorbate-based activity, the enzyme showed a little NADH-NO oxidoreductase activity which was not inhibited by antimycin A. The enzyme lost activity with a half-life of about 2 days at 4 degrees C but could be preserved at -20 degrees C and in liquid nitrogen. It seemed not to be inactivated by aerobic solutions. These observations, and the recent ones by Carr and Ferguson (Carr, G.J., and Ferguson, S.J. (1990) Biochem. J. 269, 423-429) with a partially purified preparation of nitric oxide reductase, establish that the enzyme from Pa. denitrificans is a cytochrome bc complex which resembles that from Pseudomonas stutzeri (Heiss, B., Frunzke, K., and Zumft, W.G. (1989) J. Bacteriol. 171, 3288-3297). There would appear to be no functional relationship between nitric oxide reductase and a Mr = 34,000 peptide of Pa. denitrificans membranes reported previously to be present in purified preparations of a nitric oxide reductase (Hoglen, J., and Hollocher, T.C. (1989) J. Biol. Chem. 264, 7556-7563).
Amino Acids↗
[Four years experience with a periodontal health education program for 12-15-year old Dutch schoolchildren].
A dental health education program on periodontal disease for 12-15-years-old schoolchildren during a period of four years (1986-1989) was organised. A course package was developed for secondary schools, whereby an evaluation of the course material was carried out both quantitatively and qualitatively. The amount of material requested by the schools exceeded the expectations. The content of the material appeared to be adequate for both the pupils as well as teachers. The education strategy was successful in reaching the target group. The school appears to be an excellent place for this type of dental education program. For the future it may be advisable to focus more on a target group with a low education level.
Adolescent↗
Chemical modification of equinatoxin II, a lethal and cytolytic toxin from the sea anemone Actinia equina L.
The role of arginine and tyrosine in cytolytic properties of equinatoxin II, isolated from the sea anemone Actinia equina L., was studied by means of chemical modifications. The toxin was modified with 2,3 butanedione and tetranitromethane, respectively. The extent of modification and physico-chemical properties of the modified proteins were checked with amino acid analysis, isoelectric focusing and circular dichroic spectra. Extensive treatment of the toxin with 2,3 butanedione modified seven arginines and also two tyrosines, with resulting loss of hemolytic activity. Modification of two out of nine arginine residues resulted in a 25% loss of hemolytic activity, whereas nitration of three out of ten tyrosines decreased hemolytic activity by 95%. The nitrated toxin had at least a 30-fold higher i.v. LD50 than the native toxin. None of the modifications significantly affected the secondary structure of the toxin as revealed by the CD spectra. It is concluded that tyrosine residues are involved in both lethal and cytolytic activity, while the role of arginine residues is not evident because of the non-specific alteration of tyrosine residues with 2,3 butanedione.
Amino Acids↗
Group therapy in a general practice setting for frequent attenders: a controlled study of mothers with pre-school children.
The frequent attendance of women suffering from anxiety and depression is a common problem in general practice and the problems are often externalized through the women's children. A small controlled study was carried out in a general practice surgery to see whether demand for medical attention by mothers of pre-school children would decrease after they attended a discussion group. Twenty women who fulfilled the study criteria of more than double the national average consultation rate for their age group and of having at least one pre-school child, were sequentially allocated to a treatment or control group. The group therapy was held over two terms of 10 sessions, each of 90 minutes, and was led by a psychologist and a general practitioner. Consultation rates (including surgery visits, house calls and prescription requests) were recorded for five consecutive six-month periods before and after the intervention. At follow-up six months after the end of the treatment a significant reduction in consultation rate had been achieved and maintained by the treated group compared with the controls (P<0.01). This study shows the value of attending to the cause of frequent consultation as well as to the complaints presented.
Anxiety↗
The prevalence of Sjögren's syndrome in adult women.
OBJECTIVES: The aim of this study was to determine the prevalence of primary Sjögren's syndrome (pSS) according to European criteria (1993) and to the US-European Consensus Group (US-EU) criteria (2002) in adult women in Bornova, Izmir, Turkey. MATERIALS AND METHOD: The study was designed as a two-phase cross-sectional survey consisting of a baseline questionnaire and collection of blood samples and clinical examination. In the initial phase, positivity for autoantibodies Ro(SS-A), La(SS-B), rheumatoid factor (RF), and anti-nuclear antibodies (ANA) was determined, and in the clinical phase, clinical examination, salivary and ocular tests were performed. Minor salivary gland biopsy was performed for those who had at least three of these five criteria positive. RESULTS: In our sample the prevalence of SS was 1.56% [95% confidence interval (CI) 0.92-2.66] according to the European criteria and 0.72% (95% CI 0.33-1.57) according to the US-EU criteria. CONCLUSION: To prevent the loss in diagnosis of pSS, the addition of ANA, RF, and tear break-up time (BUT) tests to US-EU criteria would be appropriate.
Adolescent↗