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At least 991 records · Page 55Linked to original sources
PubMed1987

Oxidation of salicylates by stimulated granulocytes: evidence that these drugs act as free radical scavengers in biological systems.

Although salicylates have been used for centuries as treatment of inflammatory diseases, the mechanism of action of these drugs is still not clear. Aspirin (acetylsalicylic acid) and other nonsteroidal anti-inflammatory drugs (NSAID) inhibit prostaglandin biosynthesis, a property that appears to explain part of their anti-inflammatory activity. However, this mechanism does not appear to explain the anti-inflammatory properties of salicylic acid, which is a major metabolite of ASA in vivo. Results of prior studies in our laboratory have established that benzoic acid, the parent compound of the salicylate group of drugs, is decarboxylated and hydroxylated by the hydroxyl free radical (OH.) produced by stimulated granulocytes. These observations suggested that salicylates might be similarly metabolized by granulocytes. If so, the capacity of salicylates to rapidly react with OH. might relate directly to their known anti-inflammatory properties. Preliminary experiments established that salicylic acid and aspirin were decarboxylated by the hydroxyl free radical generated by the enzyme system xanthine-xanthine oxidase. We then studied the metabolism of salicylates by human granulocytes. Unstimulated granulocyte suspensions did not oxidize ASA or salicylic acid. However, suspensions stimulated by opsonized zymosan particles rapidly oxidized both substrates in pharmacological concentrations. The rate of oxidation of salicylic acid was 16-fold higher than benzoic acid, whereas the rate of oxidation of ASA was four-fold higher. The reaction was oxygen dependent and could be inhibited by known hydroxyl scavengers, particularly dimethylthiourea. The reaction could also be inhibited by superoxide dismutase and azide, indicating that O-2 and heme or an iron-dependent enzyme were required for the reaction. The reaction was not impaired by compounds known to react with the HOCL and the chloramines generated by stimulated PMN. Furthermore, salicylic acid in high concentrations did not impair the HMPS pathway, the production of O-2 or the production of H2O2 by granulocytes. These data provide evidence that salicylates are rapidly oxidized by the hydroxyl free radical produced by granulocytes and not O-2, H2O2, or HOCL. This capacity of salicylates to react rapidly and selectively react with OH. may directly relate to their anti-inflammatory properties. In addition, results of our experiments indicate that stimulated granulocytes acquire the capacity to metabolize these drugs. Therefore, several metabolites of salicylates may be produced at a site of inflammation, all of which may have altered biological activity compared with the parent compound.

Aspirin↗
PubMedDate not supplied

[Effect of initiated spores on the resistance of nongerminated resting forms of Bacillus cereus remaining in the suspension to the action of damaging agents].

The elevated resistance of a Bacillus cereus spore suspension against the action of UV was found to depend on the quantity of resting forms initiated in the suspension prior to an irradiation. The resistance against UV increased 80-50 times if 60-90% of spores were initiated in the suspension as compared to that of the original resting forms. When suspensions containing 40% of non-germinated B. cereus spores were kept at 4 degrees C for 14 days, the latter became 10 and 14 times more resistant to elevated temperature (90 degrees C) and chloramine (2.5%), respectively, as compared to control intact spores. The higher resistance of non-germinated spores against the action of physical and chemical damaging agents was registered within the entire period of experiments (over three months). This phenomenon was not observed if ca. 100% of spores were initiated in a suspension. The resistance of initiated spores against the action of UV was 40 times lower than that of B. cereus resting forms.

Bacillus cereus↗
PubMed1977

Iodinated E. coli 70S ribosomes as a radiocolloid of uniform particle size for lymph-node and liver scanning.

As an example of the use of biologic particles as carriers for radioactive tracers, E. coli 70S ribosomes were labeled with I-125 using chloramine-T. The labeled ribosomes, after treatment with glutaraldehyde, were injected into rabbits either subcutaneously (through the dorsum of the foot) or intravenously (through the ear). After subcutaneous injection, 40% of the activity accumulated in the lymph nodes during the first 5 hr, and the 70S ribosomal particles were shown to remain within the lymphatic system for at least 8 hr. After intravenous injection, 71% of the activity was detected in the liver within minutes by scintigraphic techniques. The effective half-time of the label in the liver from glutaraldehyde-treated I-125-tagged 70S ribosomal colloidal particles is 4-5 hr. No pyrogenic response was observed. Barring any deleterious side effects, the results indicate that biologic cell components of definite dimensions (in this case E. coli 70S ribosomes about 20 nm in diam) could be considered as radiocolloids for lymph-node and liver imaging.

Animals↗
PubMedDate not supplied

Radioreceptor assay of human prolactin using rabbit mammary receptors.

The purpose of this work is to develop the procedures for the preparation of the reagents suitable for the radioreceptor assay (RRA) of human prolactin (Prl). Human purified Prl (NIAMDD-hPrl-16) was labelled with 125I by the Chloramine-T or alternatively by the lactoperoxidase method. As reference preparation we used Prl isolated from the ethanolic step of the routine procedure for the preparation of human growth hormone (hGH) for clinical purposes. The lactogenic receptors were prepared from the pregnant rabbit mammary gland previously stimulated with insulin, cortisone and dried thyroid extract. The final receptor preparations obtained by ultracentrifugation contained 8.85-39.36 mg protein per ml. The prolactin was measured in the human sera and in our hPrl preparations by a double antibody radioimmunoassay (RIA) system using the NIAMDD reagents. We developed a RRA system for hPrl using rabbit mammary receptor preparations with a protein concentration of about 4 mg/ml. The comparative competition showed the same magnitude of the inhibition of the tracer receptor binding of hPrl and hGH. This interference of hGH makes difficult the assessment of the specificity of the hPrl-RRA system otherwise accountable by the structural and/or biological relationship of the three lactogenic hormones: hPrl, hGH and human placental lactogen (hPL). Studies concerning the preparation of a purified and solubilized rabbit mammary receptor and of an antiserum for it are in progress in our laboratory with the objective to provide a useful tool for the investigation of the lactogenic receptor structure and function relationship.

Animals↗
PubMed1987

A versatile procedure for the radioiodination of proteins and labeling reagents.

For tracer or analytical studies it is often useful to label proteins by direct iodination or by reacting them with an iodinated reagent. A simple iodination technique with hydrogen peroxide is described for use with either carrier-free or low-specific-activity iodine. The method introduces less oxidative damage to proteins than any other procedure tested, yet the efficiency of labeling approaches that offered by the chloramine T or Iodogen methods. The method has been applied to the facile and inexpensive preparation of the iodinated Bolton-Hunter reagent. This peroxide iodination procedure should be particularly useful for labeling proteins or peptides for structural investigations or for immunoassays.

Chloramines↗
PubMedDate not supplied

Cancer mortality and the method of chlorination of public drinking water: St. Louis City and St. Louis County, Missouri.

St. Louis City and St. Louis County, Missouri share the same public drinking water source, namely the Missouri River. The 'all cancer' and most organ specific cancer mortality rates have been consistently and considerably higher for St. Louis City than for St. Louis County for the period 1960 through 1972. A change in the St. Louis County water treatment process, which included increasing the chlorine dosage and delaying the addition of ammonia to form chloramines until just prior to distribution, was instituted in 1955. St. Louis City has, by contrast, continued the lower chlorine level and early ammoniation. Trend analysis using the period 1960-67 and 1972-76 showed higher percentage as well as net cancer mortality rate per million increases for large bowel, liver and bladder cancers for St. Louis County. An apparent association between a probable increase in trihalomethane production in the St. Louis County water since 1955 and an increase in these specific cancer rates which exceed the increases in the St. Louis City rates appears to have been shown. This does not imply causality but is in general agreement with other studies which have examined water chlorination and cancer mortality.

Adult↗
PubMedDate not supplied

[Study of the toxic properties of preservatives used in water reclamation systems].

The comparative toxicity of halogen-containing oxidizing agents was investigated with the purpose of their utilization as urine preservatives in water reclamation systems. It was found that the high toxicity of the agents (LD50 of agent 1 was 15.7 +/- 1.1 mg/kg and LD50 of agent 2 was 23.0 +/- 1.2 mg/kg when injected i.p. to white mice) was distinctly related to their low pH in water solutions (pH 3-4). In neutral solutions the toxicity of agent 1 decreased 35 times and that of agent 2-12 times so that they can be classified as moderately toxic substances. Using an isolated frog heart according to Straub, it was shown that solution neutralization with 20% NaHCO3 also decreased the toxic effect of the above agents, making them similar to chloramine B, a well-known disinfectant. The above agents were found to be rapidly inactivated when stored in low concentrations and to remain highly stable when stored in concentrated solutions.

Animals↗
PubMedDate not supplied

[Non-allergenic treatment of varicose ulcers].

The fundamental element in the treatment of a varicose ulcer is the elimination of venous stasis. However, a local treatment is called for in the acute stage of the ulcer. This leads to the healing over of the ulcer or, at least, to its transformation into a granular and clean wound which can then be given radical treatment--either the surgery or the sclerotherapy of the varices. In most cases the treatment is ambulatory and consists of the application of a dry gauze compress covered with a foam rubber pad and an adhesive elastocompressive bandage. In certain cases the ulcerous crust is removed with chloramine. Less often, in the case of an old ulcer, with allergised and inflamed periulcerous tissues, the patient is hospitalized for a period of about 2 to 8 days before undergoing the ambulatory elastocompressive treatment. The simple treatments ensure the rapid healing of the ulcer, as long as it is really of venous origin.

Bandages↗
PubMed1979

Three different radioiodination methods for human spleen ferritin compared.

We compared three different methods for radioiodination of human spleen ferritin. Tracers prepared by direct oxidative iodination with use of Chloramine T or 1,3,4,6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril (Iodogen) were structurally altered by the labeling procedure, as was made apparent by gel filtration and electrophoresis on polyacrylamide gel. Tracers prepared by conjugation to radioiodinated N-succinimidyl-6-(4-hydroxyphenyl)propionate retained their structural integrity, as assessed by physicochemical methods. Such tracers bound more than 90% in antibody excess, yielded self-displacement curves parallel to unlabeled ferritin standards, and retained their immunoreactivity for nine weeks. By contrast, immunological activity and stability of tracers prepared by the oxidative methods were less satisfactory. Tracers prepared by using lodogen were unsuitable for use in the ferritin radioimmunoassay because of shallow standard-inhibition curves and poor binding in the absence of added standard. Thus, we found the conjugation procedure to be the most suitable of the three methods for preparation of spleen-ferritin tracers.

Chloramines↗
PubMed1975

Preparation and chemical characterization of radioiodinated bleomycin.

None of the radionuclides with which bleomycin has been labeled have chemical and nuclear properties that are entirely satisfactory for in vivo tumor localization. Bleomycin has been radioiodinated by the iodine monochloride, chloramine-T, and lactoperoxidase methods. Iodine monochloride proved to be the preferred method and conditions were developed whereby 80% of radioiodide was covalently bound to bleomycin. Bleomycin (140 mug) was added to 200 mul of saline/citrate buffer (pH 7.0) followed by radioiodide and iodine monochloride. This reaction mixture was incubated for 1 hr and purified by Sephadex G-10 chromatography. The iodine monochloride reaction product underwent hydrolytic deiodination in vitro at a rate of about 1.2%/day (0.15 M NaCl, 37 degrees C). Bleomycin A and B components were radioiodinated with equal efficiency on a mole fraction basis.

Bleomycin↗
PubMed1984

Organization of proteins in mammalian mitochondrial ribosomes. Accessibility to lactoperoxidase-catalyzed radioiodination.

To assess the relative exposure of individual ribosomal proteins (r-proteins) in the large and small subunits of the bovine mitochondrial ribosome, we used a double label iodination technique. Regions of r-proteins exposed in purified ribosomal subunits were labeled with 131I using the lactoperoxidase-catalyzed iodination system, and additional reactive groups available upon denaturing the r-proteins in urea were labeled with 125I using the chloramine-T mediated reaction. The ratio of 131I to 125I incorporated into individual proteins under these conditions is representative of the degree of exposure for each of the proteins in the subunits. In this manner, the r-proteins have been grouped into 3 classes depending on their degree of exposure: high exposure, intermediate exposure, and essentially buried. While both subunits have a few proteins in the "highly exposed" group, and a large number of proteins in the "intermediate exposure" group, only the large ribosomal subunit has an appreciable number of proteins which appear essentially buried. The more buried proteins may serve mainly structural roles, perhaps acting as "assembly proteins," since many from this group bind to ribosomal RNA. The more superficially disposed proteins may comprise binding sites for macromolecules that interact with ribosomes during protein synthesis, as well as stabilizing the association of the large and small subribosomal particles.

Animals↗
PubMed1984

Hydrophobic residues involved in the interaction between protomers of the bovine growth hormone dimer. Methionine and tyrosine residues.

The bovine growth hormone dimeric form covalently stabilized by cross-linking with dimethyl suberimidate (DMS) and the hormone modified by DMS without forming covalent links with other hormone molecules (DMS-bGH) were oxidized with chloramine-T at molar-ratios of 2 and 50 with respect to methionine content. The extent of oxidation undergone by each methionine residue, estimated on the purified tryptic peptides, closely resembled that obtained for the native hormone, thus suggesting that methionine residues are not involved in the protomers interaction area. Evaluation of the reactivity of tyrosine residues toward tetranitromethane indicated that, in both the covalent dimer and DMS-bGH, tyrosine residues 35, 174 and 142 are the more susceptible to undergo reaction. Net charges can be induced in the iodotyrosine residues in the iodinated hormone, by setting the pH at 10.5. At this pH, dissociation of a fraction of uniformly iodinated hormone was observed in the derivatives containing 2 or more iodine atoms, indicating that tyrosine residues might integrate the contact area between protomers.

Chloramines↗
PubMed1984

Interference of endogenous lactoperoxidase antibodies in a solid-phase immunosorbent radioassay for antibodies to protein hormones.

Interference of endogenous antibodies to lactoperoxidase (EC 1.11.1.7) has been demonstrated in a solid-phase immunosorbent radioassay for the detection of antibodies to protein hormones. On enzymic iodination with lactoperoxidase, a little of the 125I is incorporated in the enzyme itself by self-iodination. Because the 125I-labeled lactoperoxidase was not removed from the tracer by chromatography on Sephadex G-50, G-100, and G-200 columns, endogenous antibodies to the enzyme, which were present in 25 of 28 sera from apparently healthy individuals, were detected in conjunction with the measurement of antibodies to growth hormone (somatotropin), prolactin, and thyroglobulin, thus causing false-positive results. Contaminating radioactive lactoperoxidase can be removed by adsorption chromatography on cellulose or by liquid chromatography, and can be avoided by performing the iodination with immobilized lactoperoxidase or with Chloramine-T.

Animals↗
PubMed1984

[Preparation and properties of chlorination-damaged P. aeruginosa suspensions].

The preparation of suspensions of bacterial cells impaired by the action of chlorine require a very accurate standardization of all the procedural detail of controlled experimental impairment by chlorine. All measures suitable to spread the kinetics of reduction of bacterial numbers in time will facilitate the reproducibility of results. The exact amount of hypochlorite--determined experimentally prior to the actual test--is transformed to chloramine at 0 degrees C then a defined quantity of bacteria is added. After different periods of contact samples are taken and stabilized by adding thiosulphate of sodium. When the bactericidal action is not abrupt but sufficiently drawn out a relatively high proportion of bacteria impaired by chlorine but still viable is obtained (50-90%). In suspension the proportion remains relatively stable during storage in the refrigerator (4 degrees -6 degrees C). Resuscitation experiments carried out with suspensions of organisms damaged as explained above showed resuscitation times of 3 h in casein soy broth not to grow as well as those after 24 h of resuscitation. Obviously the process of reparation after impairment by chlorine must be assumed to be relatively slow under these conditions.

Bacteriological Techniques↗
PubMed1984

[Comparative iodination of a series of allergens].

The study of 27 allergens, carried out with the use of the standard technique of chloramine iodination by Hunter's method, revealed that the biological properties of the allergens were not essentially related to their capacity for binding 125I, this capacity being, on the whole, low. The blood sera of patients with allergic diseases were found to be no different from the blood sera of healthy persons in their capacity for binding 125I.

Allergens↗
PubMed1984

The effects of chronic administration of chlorine dioxide, chlorite and chlorate to normal healthy adult male volunteers.

The physiological impact of chronic 12 week ingestion of chlorine dioxide and its byproducts, chlorite and chlorate, was compared to the effects of chlorine, chloramine and untreated water. The water disinfectant solutions were administered daily (500 ml, 5 ppm) to normal healthy adult male volunteers. An extensive battery of tests was used to evaluate the physiological impact of the ingested water disinfectants. Upon analysis of both quantitative and qualitative parameters it was concluded that the 12 week chronic administration of chlorine dioxide and its byproducts was accompanied by no clinically important physiological effects.

Adult↗
PubMed1984

High-level iodination of monoclonal antibody fragments for radiotherapy.

Two different murine monoclonal antibody Fab fragments specific for p97, a melanoma-associated antigen, were labeled with I-131 at high activity levels without excessive chemical damage. Up to 20 mg of Fab were labeled with up to 300 mCi of I-131 using the chloramine-T method and large working volumes at room temperature. As much as 90% of the initial activity was recovered as labeled product. The labeled Fabs varied in their sensitivity to radioiodination damage, as measured by an in vitro cell-binding assay. Radioiodination was performed safely using a remote iodination apparatus. The final product was of radiopharmaceutical quality suitable for clinical diagnosis and experimental radiotherapy in humans.

Animals↗
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↗