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PubMed2004

Effects of phosphoinositide cycle modifiers on apoptosis of peritoneal macrophages.

Hydrogen peroxide stimulates apoptosis of zymosan-activated rat peritoneal macrophages. Phosphoinositide cycle modifiers enhance the proapoptotic effect of H(2)O(2) in a concentration of 1 mM and necrosis-stimulating effect of H(2)O(2) in a concentration of 10 mM. Disorders in phosphoinositide metabolism and impaired reaction of the cell to proinflammatory agents are the cause of programmed cell death. Rejection of defective cells can be realized via variation of H(2)O(2) concentration.

Aluminum Compounds↗
PubMed1981

[A 125I-thyronine derivative of high specific activity and radiochemical stability (pseudo-T4) (author's transl)].

Under the described reaction conditions for the synthesis of 125I-labelled thyroid hormones by the chloramine-T method, electrophilic substitution of the phenolic ring at positions 3' and 5' is accompanied by an exchange reaction. The proportions of mono- and diiodo-thyronine derivatives formed in this reaction depend on the specific activity of the 125I starting material. Doubly labelled molecules are far less stable than mono products, because the radioactive decay of one iodine atom is followed by destruction of the molecule itself, and the remaining iodine atom is released as I-. In the case of thyroxine with two equivalent substitution positions, there is always a high yield of doubly labelled molecules. By using a thyronine derivative containing a non-radioactive bromine atom in one of the two ortho positions of the 3,5-diiodothyronine molecule, it was possible to produce a "pseudo-T4" of high specific activity and excellent radiochemical stability by radioiodination of the second position. The immunological properties resemble those of T4. This compound may be useful as a tracer for the determination of free T4.

Bromine↗
PubMed1995

In vitro oxidative damage to tissue-type plasminogen activator: a selective modification of the biological functions.

OBJECTIVE: Tissue-type plasminogen activator (t-PA) is an important component of the blood fibrinolytic system responsible for thrombus dissolution. It is often required to function under oxidative stress, and exogenous t-PA is used clinically in the treatment of acute myocardial infarction (AMI). The aim of this study was to examine alterations in the residual activity of t-PA pre-treated with certain oxidants. METHODS: Recombinant t-PA (rt-PA) and native t-PA (nt-PA) were pre-treated with freshly generated hypochlorous acid (HOCl) and chloramine T at varying concentrations. The amidolytic activity, the plasminogenolytic activity and the fibrin-binding affinity were then examined using chromogenic assays based on S-2288 and S-2251. RESULTS: The amidolytic activity of t-PA was surprisingly found to be rather sensitive (IC50 1 and 12 mumol/1, respectively), and the plasminogenolytic activity rather resistant to pre-treatment with HOCl and chloramine T. The fibrin binding study of treated t-PA revealed substantial loss of binding to CNBr-digested fibrinogen (FDP-CNBr). The velocity of t-PA in reaction with plasminogen remained the same as non-treated t-PA. The possible mechanisms of this asymmetrical oxidative modification of the biological functions are also discussed. CONCLUSIONS: (1) The catalytic activity of t-PA and the binding affinity for its large-molecule substrate plasminogen, rather than the small-molecule substrate S-2288, are highly resistant to oxidative damage; (2) the fibrin-binding affinity of t-PA can be selectively and asymmetrically damaged by exposure to these oxidants. Thus it is possible that the characteristic advantage of thrombus selectivity of t-PA in both spontaneous thrombolysis and thrombolytic therapy may be diluted in circumstances where toxic and reactive oxidants exist.

Amino Acid Sequence↗
PubMed1978

Intestinal secretion of sulphanilic acid by the isolated mucosa of guinea pig jejunum.

Tissue uptake and transepithelial permeation of 35S-sulphanilic acid were studied in the isolated guinea pig jejunal mucosa. Methoxy-3H-inulin added simultaneously served as a marker for the extracellular space and permeability of paracellular shunt pathways in the preparation. The uptake of sulphanilic acid from the blood side exceeded that from the luminal side 4--7 fold. The permeation of the acid was strongly correlated to the permeation of inulin. At 5 micrometer and 2.5 mM sulphanilic acid under aerobic conditions, the regression lines for the permeation from lumen to blood pass almost through the origin, while the regression lines for the permeation from blood to lumen intersect the ordinate at a positive Y-value. In anaerobiosis, at 25 mM sulphanilic acid, or with addition of p-toluene sulphonic acid only one regression line is obtained for the permeation in both directions. It is concluded that besides a permeation of sulphanilic acid across inulinpermeable shunt pathways an active transport system exists, which transfers the acid from the blood to the luminal side. This system is saturable, depends on aerobic energy and exhibits mutual inhibition by a structurally related compound. The results are comparable to those previously obtained with cardiac glycosides and quaternary ammonium compounds, in the same preparation. Thus, the intestinal mucosa is able to secrete the same classes of compounds which are secreted by the liver and the kidney.

Aerobiosis↗
PubMed1984

Modification of sodium channel inactivation in single myelinated nerve fibers by methionine-reactive chemicals.

Several methionine-reactive reagents, including N-bromoacetamide, N-bromosuccinimide, chloramine-T, and N-chlorosuccinimide, irreversibly slowed and prevented Na channel inactivation in single myelinated nerve fibers, whereas sulfhydryl- or tyrosine-modifying reagents had little effect. The activation process was not modified by the reagents that altered inactivation and could be modulated normally by Ca++ ions and Centruroides scorpion toxin II alpha. These results suggest that externally applied N-bromoacetamide and its related compounds specifically affect Na channel inactivation by modifying methionine residues of the channel.

Acetamides↗
PubMed2006

Transgenic mouse model for rapid pharmacodynamic evaluation of antiandrogens.

Persistent androgen receptor signaling has been implicated as a critical factor in prostate cancer progression even at the hormone-refractory stage and provides strong rationale for developing novel androgen receptor antagonists. Traditional models for in vivo evaluation of antiandrogens are cumbersome because they rely on physiologic end points, such as the size of androgen-dependent tissues. Here, we describe a transgenic mouse (ARR2 Pb-Lux) that expresses luciferase specifically in the prostate in an androgen-dependent fashion. This signal is reduced by castration or by treatment with bicalutamide and can be quantified through noninvasive bioluminescent imaging. ARR2 Pb-Lux mice provide a novel method for rapid pharmacodynamic evaluation of novel pharmacologic compounds designed to inhibit androgen receptor signaling.

Androgen Antagonists↗
PubMed2006

Screening for metabolically stable aryl-propionamide-derived selective androgen receptor modulators for doping control purposes.

Anabolic agents have been among the most frequently detected drugs in amateur and professional sport. A novel class of therapeutics presumably complementing anabolic steroids in the near future includes so-called selective androgen receptor modulators (SARMs) that have been under clinical investigations for several years. Although not yet commercially available, their potential for misuse in sports is high. Four aryl-propionamide-derived SARMs were synthesized in order to establish a fast and robust screening procedure using liquid chromatography/electrospray ionization tandem mass spectrometry. Synthesized compounds were characterized by high-resolution/high-accuracy mass analysis employing a linear ion trap-Orbitrap hybrid mass spectrometer while routine analyses were conducted on a triple-quadrupole mass spectrometer. Characteristic product ions obtained by collision-induced dissociation were found at m/z 289 and 261 as well as m/z 269 and 241 representing the bisubstituted aniline residues of selected model compounds. Assay validation was performed regarding lower limit of detection (1 ng/mL), recovery (85-105%), intraday precision (7.6-11.6%) and interday precision (9.9-14.4%), and precursor ion scan experiments on diagnostic product ions enabled the detection of a structurally related compound at 50 ng/mL.

Anabolic Agents↗
PubMed1998

Which conditions promote a remanent (persistent) bactericidal activity of chlorine covers?

The interaction of disinfectants containing active chlorine compounds (hypochlorite, chloramine T) with skin surfaces produces a so called chlorine cover which is a true chemical transformation of the protein matrix of the outermost horny skin layer by forming covalent N-Cl bonds. Though its intensity can easily be measured, the results on its remanent (persistent) bactericidal action until now have not been described consistently. While Gottardi and Karl observed a well-defined remanent action which correlated with the cover strength in the artificially with E. coli contaminated arm, Koller, Rotter, and Gottardi were not able to prove it, neither in artificially contaminated hands nor in the case of the resident bacterial colonization. To clarify these not consistent results, the bactericidal activity of chlorine covers on transient (dry contamination of the finger tips with Micrococcus luteus) as well as on resident colonization (after wearing gloves for 3 h) has been re-investigated using contact plates for recovering the bacteria. The results are showing that the remanent bactericidal action of chlorine covers strongly depends on the skin milieu, with moist conditions caused by sweat (surgical gloves) favoring the bactericidal activity. Elution experiments prove that protein constituents (detected by UV-spectrometry) continuously are transported to the skin-surface. It is obvious that the latter equilibrate with the chlorine cover by forming bactericidal N-Cl compounds with the effect that oxidation capacity fixed at the protein matrix is mobilized enabling the remanent bactericidal action.

Chloramines↗
PubMed2001

The influence of plasma on the disinfecting activity of the new antimicrobial agent N-chlorotaurine-sodium in comparison with chloramine T.

The phenomenon of increasing bactericidal activity of N-chlorotaurine in the presence of chlorine-consuming material has been investigated both on a chemical-analytical and microbiological basis using plasma as substrate and chloramine T for comparison. Chlorine consumption assessed by iodometric titration showed a biphasic time-course with a very fast loss of oxidation capacity within one minute (N-chlorotaurine: -9.3%, chloramine T: -16.8%) followed by a slow loss which could still be detected after 24 h (total loss -61.7% and -74.1%, respectively). Killing curves revealed that an increase in bactericidal activity, in spite of improved consumption, did not occur with all strains, and could be detected only at a certain degree of consumption. Escherichia coli and Pseudomonas aeruginosa showed the most pronounced effect, Streptococcus pyogenes and Proteus mirabilis a medium-sized one, while it was absent in Staphylococcus aureus. With chloramine T, an increase in bactericidal activity could not be proved. The chemical basis of these consumption effects can be reduced to four reaction types: oxidation of thiols; chlorine substitution of activated C-H compounds; transhalogenation; and hydrolytic degradation of N-chloro-alpha-amino acids and -peptides emerging by transhalogenation. The initial fast loss of oxidation capacity can be attributed mainly to oxidation of thiols, while the subsequent slower decrease is caused by the other types of reaction. The increase in bactericidal activity, on the other hand, can be explained by transhalogenation, leading to the formation of more bactericidal N-chloro compounds by which the loss of N-chlorotaurine is over-compensated.

Animals↗