[Comparative quantitative studies of proteins by radial immunodiffusion, laser-nephelometry and turbidimetry].
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Humans↗
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The two dimensional structure of tetrazolium-mucopolysaccharide complexes deduced from reactivity studies.
The formation of complexes between mucopolysaccharides and tetrazolium salts has been studied both by turbidimetry and nephelometry. The technique of laser nephelometry allows the detection of colloidal aggregates in systems which may, by turbidimetric methods, be ambiguous. The results indicate that binding of tetrazolium salts to polyanions can result in soluble as well as insoluble complexes; the monotetrazolium salts form soluble complexes and the ditetrazolium compounds form insoluble complexes. The insoluble complexes are stable at relatively low pH, and are disrupted during reduction to the formazan. Complex formation is decreased at high ratios of heparin to tetrazolium, and divalent cations, even at high concentration, do not precipitate mucopolysaccharides. It is concluded that stable ionic interactions with spatial charge separation are responsible for the cross linking of the mucopolysaccharides and the formaiton of large insoluble aggregates.
Chemical Phenomena↗
[Quantitative immunologic determination of specific proteins by kinetic turbidimetry].
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Antigen-Antibody Reactions↗
Measurements of precipitin reactions by difference turbidimetry: a new method.
A new method for the measurement of precipitin and flocculation reactions between antibodies and antigens has been developed. The technique, called difference turbidimetry, involves the use of tandem cuvettes providing the opportunity of using separated and unmixed antigen and antibody as blank solutions for spectrophotometric readings in the ultraviolet wavelength range. By use of this technique genuine difference turbidity spectra have been recorded for the reaction between human serum albumin and rabbit-anti-human serum albumin IgG. It was found that difference turbidimetry at low wavelengths (e.g. 280 nm) allows the construction of precipitin curves with a very clearly expressed zoning phenomenon at a sensitivity which in terms of antigen and antibody concentrations is more than twice the sensitivity of conventional procedures. It is of special interest that the zone of equivalence differs when the same reaction between an antigen and its antibody is measured by difference turbidimetry, by absorbance of washed and redissolved precipitate, and by amount of precipitated antigen.
Antigen-Antibody Reactions↗
A practical, objective approach to the evaluation of sperm and cervical mucus in humans.
Human sperm fertility potential, expressed as a quality index (QI), was evaluated objectively from considerations of sperm velocity, percentage of motile forms, sperm density, and ejaculate volume. Turbidimetry was applied in the quantitation of sperm velocity. High QIs (700) were characteristic of semen samples that were capable of penetrating cervical mucus in capillary tube penetration tests, while low QIs (80) were associated with specimens that did not penetrate mucus. The rate of decline in QI as a function of time postejaculation was determined for samples stored at 37 degrees C and at ambient temperature, providing correction factors for the comparative evaluation of semen samples analyzed at different times. The penetrability of cervical mucus was determined by capillary tube penetration testing. Subsequent chemical analysis of sperm-penetrable and impenetrable samples indicated that the concentrations of mucus nondialyzable solids (NDS), mucins, and soluble proteins were significantly higher in impenetrable specimens. These characteristics were also observed in impenetrable mucus obtained from patients with cervical factor infertility. These studies indicate that it is now feasible to employ mucus [NDS] in the diagnosis of cervical factor infertility and turbidimetry in the evaluation of human sperm quality.
Cervix Mucus↗
[Comparative study of the biological activity of tetracycline hydrochloride and morphocycline by using reverse turbidimetry].
The method of back turbidimetry was used for determination of the biological activity of the antibiotics, since high turbidity of the nutrient medium with Staph. aureus as the testculture prevented from direct measurements. Broth containing phosphate buffer, Staph. aureus and definite concentrations of the antibiotic was used as the reference solution. The experiments showed that the differences in the biological activities of tetracycline hydrochloride and morphocycline may be found with the method of back turbidimetry 6-8 hours after the microbe cultivation on media with the antibiotics.
Culture Media↗
Re-evaluation of turbidimetry of proteins by use of aromatic sulfonic acids and chloroacetic acids.
From studies on 11 different proteins (including native albumin and albumin with reduced disulfide-bridges) treated with sulfosalicylic, 2-naphthalenesulfonic, toluenesulfonic, dichloroacetic, or trichloroacetic acids, we elucidate the interactions determining the resulting turbidities and other factors affecting turbidities, and we discuss the clinical utility of such turbidimetry. At least three interactions are important in determining turbidity: reduction of positive charges on the protein, hydrogen bonding of the non-ionized chloroacetic acids with the protein, and hydrophobic interaction of the aromatic sulfonic acids with albumin. Turbidity varies appreciably with the species of acid and protein, concentrations of acid, temperature, and standing time after acid is added. We conclude that this technique should be restricted to confirming proteinuria.
Albumins↗
[Determination of lysozyme in biological fluids by a semi-automatic kinetic technique. Discussion of the method (author's transl)].
A rapid and semi-automatic determination of lysozyme in biological fluids using kinetic analysis and turbidimetry is described and compared to other commonly used techniques. The specificity of the method is satisfactory while that of clarification of a gel medium is apparently not. Normal values and standard errors for plasma, urine, and leucocytes are given. A standardised expression of lysozyme activity is proposed and discussed. The importance of the means by which the blood sample is collected and prepared is underlined: plasma, decanted soon after collection, is preferable to serum.
Autoanalysis↗
Recombination of ciliary dynein of Tetrahymena with the outer fibers.
Recombination of ciliary dyneins of Tetrahymena pyriformis with the outer fibers was investigated using turbidimetry, co-sedimentation analysis and electron microscopy. As reported by Gibbons, 30S dynein could recombine with the outer fibers, while 14S dynein did to so a lesser extent. At acidic pH, however, most of the 14S dynein was also rebound to the outer fibers. When an excess of crude dynein fraction was added to the outer fiber fraction at pH 8.2, electron microscopic observations showed that the outer doublet microtubules were decorated not only with arms but also with other electron-dense materials. On the other hand, when crude dynein fraction was mixed with the outer fibers in an appropriate quantity, only arms were reconstituted at the regular positions of A-subfibers. ATP had an inhibitory effect on the recombination of dynein with the outer fibers.
Adenosine Triphosphatases↗
Histone H1--DNA interaction. On the mechanism of DNA strands crosslinking by histone H1.
Crosslinking of DNA fibers by histone H1 or phosphorylated on Ser-37 histone H1, and by the individual fragments of the H1 polypeptide chain was studied by the method of turbidimetry. The dependence of the turbidity of DNA-protein complexes on the ionic strength in solution suggests that the condensation of H1.DNA complexes in vitro is apparently due to both specific histone-DNA interactions with the contribution of hydrogen and/or hydrophobic bonds and the formation of polycationic "bridges" fastening the DNA fibers. The effectiveness of the condensation is postulated to be a function of a proportion between the two mechanisms which in turn can be controlled by slight changes in ionic surroundings. The sharp dependence of shrinkage of H1.DNA complexes on ionic strength at "physiological" salt concentrations could provide a mechanism to regulate density and consequently the total activity of chromatin in the cell nuclei. The phosphorylation of histone H1 on Ser-37 by a specific histone kinase does not noticeably affect the pattern of DNA crosslinking by the H1.
Cations, Divalent↗
Immunochemical determination of human immunoglobulins: use of kinetic turbidimetry and a 36-place centrifugal analyzer.
We describe the measurement of human immunoglobulins IgG, IgA, and IgM in diluted sera, with diluted commercial monospecific antisera, with use of a 36-place centrifugal analyzer (RotoChem IIa; American Instrument Co., Silver Spring, MD 20920). The assay involves a two-point kinetic turbidimetric technique. The changes in absorbance at 340 nm between 10 and 255 s are taken for standard curve construction with use of a computer-generated cubic least-squares fit. Patients' samples are quickly calculated from the stored curve. Multiple time-interval readings are taken to observe the reaction kinetics. The lowest detectable concentrations are: IgG, 5 mg/L; IgA, 20 mg/L; and IgM, 20 mg/L. Correlation with radial immunodiffusion was excellent. Precision, accuracy, linearity, and sensitivity were very acceptable. Antigen or antibody excess can be easily detected. The accuracy of the proposed method when measuring idiotypic monoclonal proteins is greater than radial immunodiffusion. Up to 30 patients' samples can be analyzed at one time, and calculation of test results by use of the computer program is efficient and rapid.
Autoanalysis↗
Kinetics of the polymerization reaction of tobacco mosaic virus protein: transient-saturation type polymerization reaction.
The kinetics of the endothermic polymerization reaction of tobacco mosaic virus protein in the mild acid region was studied by means of temperature-jump (rising time of 6 sec)-turbidimetry, electron microscopy, and computer simulation. The time course profile of the turbidity increase changed from a normal one to an anomalous one as the size of the temperature-jump was made greater. The anomalous type polymerization profile, which we named the "transient-saturation" type, could be characterized by a rapid increase of turbidity and its transient saturation, and a slow increase to the final level. At a higher concentration of the protein, this transient-saturation effect was more marked, whereas the slow turbidity in the second phase occurred with a higher rate. This transient-saturation type polymerization profile was observed also in a pH-induced polymerization reaction. It was not observed in the case of the N-bromosuccinimide modified tobacco mosaic virus protein under a similar environmental change. By an electron microscopic study and computer simulation, it was revealed that in the first phase, a large number of short polymers were formed, and the concentration of the polymerizing units was rapidly reduced to the equilibrium value, and the polymerization reaction stopped transiently. In the second phase, polymer-polymer associations took place slowly and longer polymers were formed. The revlevance of the present study to the polymerization reaction of actin, myosin, and to a transient-overshoot type polymerization are discussed.
Bromosuccinimide↗
Effect of chloroquine adsorption on acid reactivity of magnesium trisilicate.
Due to the adsorption of chloroquine by magnesium trisilicate, both the BP acid absorption test and the rate of hydrochloric acid uptake, as monitored by pH measurements, were significantly reduced. This reduction was dependent on the amount of chloroquine adsorbed, since multilayer adsorption produced relatively more suppressive effects than did monolayer adsorption. The presence of adsorbed chloroquine also decreased the amounts of magnesium released in an acid medium. The inhibition of the antacid property due to chloroquine adsorption may be attributed to the occupation of the reactive sites of the antacid surface by chloroquine and to a reduction of the surface of the antacid due to flocculation of the particles.
Adsorption↗
Physicochemical properties of glycyrrhizic acid in aqueous media II: Effect on flocculation-deflocculation behavior of suspensions of sulfathiazole and graphite.
The flocculation-deflocculation behavior of sulfathiazole and graphite in aqueous solutions of glycyrrhizic acid was studied by measuring the sedimentation volume and turbidity of supernates. The dispersing effect of glycyrrhizic acid on suspension of sulfathiazole showed a maximum in the pH 3-4 region, the same pH region where the zeta-potential of sulfathiazole particles showed a negative maximum. The results were explained by the variation of degrees of ionization of glycyrrhizic acid and sulfathiazole with pH. With graphite suspensions, the pH region where the dispersing effect of glycyrrhizic acid showed a maximum shifted to a higher pH compared with sulfathiazole. This result can be attributed to the fact that graphite is a nonpolar substance so the surface properties are not affected by a pH change. Hence, the adsorption of glycyrrhizic acid occurs even in a fairly high pH range.
Adsorption↗
Autoxidation of polysorbates.
Aqueous solutions of polysorbate 20 undergo autoxidation on storage, with the peroxide number increasing and subsequently decreasing again, the acidity increasing continuously, the pH and surface tension falling and tending to level off, and the cloud point dropping sharply until turbidity begins at room temperature. The changes are accelerated by light, elevation of temperature, and a copper sulfate catalyst. At the same time, hydrolysis occurs, liberating lauric acid. Analysis of the alterations in these properties leads to the conclusion that hydrolysis has the major influence near room temperature and that oxyethylene undergoes chain shortening at temperatures above 40 degrees. However, evidence of degradation is detectable even in previously unopened commercial samples of polysorbates 20, 40, and 60, warranting attention to the stability of and standards for these surfactants as compared with the solid alkyl ether type of nonionic surfactant.
Chemical Phenomena↗
Effect of thiourea and substituted thioureas on dynein ATPase and on the turbidity response of Tetrahymena cilia.
The effects of thiourea and of several substituted thioureas -- phenylthiourea, alpha-naphtylthiourea, metiamide, and burimamide -- on dynein ATPase have been studied. The substituted thioureas are over 30 times more potent than thiourea in causing enhancement of 30S dynein ATPase activity and inhibition of 14S dynein ATPase activity. The effects of thiourea and phenylthiourea can be prevented by very low concentrations of beta-mercaptoethanol or dithiothreitol. Axonemal ATPase is also enhanced by the thioureas, but the reaction proceeds more slowly than for solubilized 30S dynein. Enhancement of 30S dynein ATPase by metiamide is prevented by low (approximately 1 microM) concentrations of ATP and, less effectively, by AMP-PNP, but not by AMP-PCP even though the latter is a stronger inhibitor of 30S dynein ATPase than is AMP-PNP. The thioureas inhibit the ATP-induced decrease in turbidity (measured as delta A350) of axonemal suspensions. Inhibition of the turbidity response is also prevented by low concentrations of beta-mercaptoethanol, but, in contrast to the irreversible enhancement of ATPase activity, inhibition of the turbidity response is largely reversible. The ability of 30S dynein to rebind onto twice-extracted axonemes is not changed by treatment with phenylthiourea or metiamide. These observations indicate that the thioureas react with at least two sets of SH or S--S groups on axonemes. Reaction with the group(s) on the 30S dynein causes an apparently irreversible enhancement of ATPase activity. Reaction with another group(s) causes a reversible inhibition of the turbidity response.
Adenosine Triphosphatases↗
Comparative studies on the biological activities of cardiotoxin, melittin and prymnesin.
The actions of cardiotoxin (CTX), melittin and prymnesin were compared on dog erythrocytes, chicken biventer cervicis muscle, rabbit conjunctiva, acetylcholinesterase, succinate-cytochrome c reductase and turbidity of the rat liver mitochondrial suspension. 1. CTX and melittin were approximately equipotent in the various biological activities, while prymnesin was not. 2. The rate of direct ehmolysis induced by CTX was slow, while that induced by either melittin or prymnesin was fast. 3. Phosphate ions, 10mM Ca++, as well as 1 mM reduced glutathione, considerably inhibited the CTX-induced hemolysis, but only slightly inhibited that induced by melittin or prymnesin. 4. CTX, melittin and prymnesin caused contracture of the chicken biventer cervicis muscle. Prymnesin was much less active in this preparation as compared with its hemolytic potency. The CTX contracture was completely inhibited by high Ca++ (10mM) medium, while the melittin contracture was not. 5. The rate of CTX contracture to reach the peak tension was increased when the concentration of CTX was increased, while the rate of melittin contracture did not change very much as the concentrations varied. 6. All three toxins caused a local irritation of the conjunctival sac of the rabbit eye. 7. Both CTX and melittin inhibited acetylcholinesterase and succinate-cytochrome c reductase activities, and also increased the turbidity of the rat liver mitochondrial suspension, while prymnesin was totally inactive in these respects. It is concluded that the mechanism of actions of these toxins may be different at the molecular level. The role of the detergent properties of these toxins in their biological activities is discussed.
Acetylcholinesterase↗
Histone: oxidation by peroxidase alters its interaction with DNA.
When histone is oxidized by peroxidase, its basicity (hence its complexing with DNA) is reduced: this reduction causes further alterations in the effect of histone upon the heat denaturation, acid precipitation, and breakdown by DNase of DNA, alterations which indicate that the regulation by histone of DNA expression may become abnormal. If oxidized species of histone should accumulate in the tissues in old age, the alteration mentioned might be a contributory factor of senescence.
Animals↗