Heat Stability Studies Research Articles

Characteristics of nonsuppressible insulin-like activity in fasting human serum.

Insulin-like activity (ILA) and nonsuppressible insulinlike activity (NSILA) of fasting normal human serum have been studied following fractionation by cation resin chromatography, or extraction with acid-ethanol or ethanol. Studies of solubility, heat stability and immunosuppressibility suggest three different fractions, none of which is immunoassayable insulin. The total activity of the fractions was usually several times that of the original serum. “Bound” NSILA, which binds to a cation resin column, appears to be a smaller molecule than “free insulin” NSILA found in the column effluent. Our studies suggest that the column effluent NSILA is converted to the smaller “bound” NSILA by acid-ethanol extraction. Although the column effluent NSILA is partially suppressible with guinea pig antiserum, only a trace amount of immunoassayable insulin was found in this fraction.

Azaguanine-resistance as a manifestation of a new form of metabolic overproduction of uric acid

A young man is described with overproduction of uric acid and several features of the Lesch-Nyhan (L-N) syndrome, including borderline normal intelligence, mild spasticity and an episode of self-mutilation. Enzymatic analyses of the activity of hypoxanthine-guanine phosphoribosyltransferase (H-G PRT), the defective enzyme in the L-N syndrome, in red cells and fibroblasts from the patient gave normal results, as did studies of heat stability and starch gel electrophoresis of this enzyme from red cell hemolysates. Red cell adenine phosphoribosyltransferase (A-PRT) activity in the patient was increased, as in patients with the L-N syndrome. Several features of purine metabolism in fibroblasts were similar to those in cell lines with H-G PRT deficiency. Both cell lines showed growth resistance to 8-azaguanine compared to cell lines from normal subjects. When the accelerated purine synthesis was measured by formate-1-C 14 incorporation into formylglycinamide ribonucleotide (FGAR) during azaserine block, both cell lines showed further stimulation of purine synthesis by hypoxanthine, whereas control cell lines showed expected feedback inhibition. Fibroblasts from the patient were more sensitive to inhibition of de novo purine synthesis by adenine than those from a normal control subject in a manner previously shown for H-G PRT deficient cell lines. A distinguishing feature was that fibroblasts from patients with H-G PRT deficiency could not grow in culture media with the folic acid antagonist aminopterin, whereas cell lines from the patient and normal control subjects could use hypoxanthine from the media for growth. We suggest that accelerated purine synthesis and clinical and biochemical similarities to the L-N syndrome, but apparently normal H-G PRT activity, constitute a distinct form of primary gout.

Alkaline phosphatase activity in virus-induced murine leukemia

The levels and properties of liver alkaline phosphatase were compared in extracts from normal and Rich leukemia virus-infected mice. There was an increase in phosphatase activity in the livers from the virus-infected mice. This increase in enzyme activity was accompanied with alterations in the enzyme properties. The phosphatase activity in the extracts from infected mice was not as dependent on magnesium ions as was the enzyme from normal mice. Studies on acrylamide gel showed different electrophoretic mobilities for the alkaline phosphatase from the two sources. Heat stability studies showed that the Mg 2+-dependent species was more stable than the Mg 2+-independent species and that the extracts from infected mice contained a much lower concentration of this Mg 2+-dependent phosphatase than did the extract from normal mice. The apparent Michaelis constant, with respect to p-nitrophenyl phosphate, was larger (sevenfold) for the extract from the infected mice. These data show that leukemia virus infection of mice resulted not only in changes in the levels of activity, but also in changes in the properties of this enzyme.

N,N‐dialkylamides of long chain fatty acids as plasticizers

AbstractA number of N,N‐dialkylamides have been prepared, characterized and evaluated as plasticizers for poly (vinyl chloride‐vinyl acetate) copolymer. Among these are the N‐oleoyl derivatives of diisopropyl, dibutyl, diisobutyl, diamyl, dihexyl, diheptyl, dioctyl, di‐2‐ethylhexyl and didecylamines. Also included are the N,N‐dibutylamides of 2‐ethylhexanoic, neodecanoic, neotridecanoic, palmitic, stearic, linoleic, erucic, ricinoleic, naphthenic, dimer, pinic, epoxystearic, animal, cottonseed, hydrogenated cottonseed, rapeseed,Limnanthes douglasii seed and parsley seed acids. Optimum low‐temperature plasticizing properties are achieved for the N‐oleoyl derivatives of dibutyl, diamyl and dihexyl amines. These low‐temperature properties are comparable to those of the adipate and sebacate plasticizers without the adverse volatility characteristics of the adipates. Compatibility of the N,N‐dialkyloleamides extends through the dihexyl derivative. A brief heat stability study of some selected plasticized polylvinyl chloride copolymer compositions indicates that the thermal stabilization of amide plasticizers is not an insurmountable problem.

Heat Stability Studies on Chelates from Schiff Bases and Polyazines of Salicylaldehyde Derivatives1

Heat Stability Studies on Chelates from Schiff Bases and Polyazines of Salicylaldehyde Derivatives¹

Additions and Corrections: Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives. II.

Additions and Corrections: Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives. II.

Additions and Corrections: Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives.

Additions and Corrections: Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives.

Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives. II

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHeat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives. IIC. S. Marvel and N. TarköyCite this: J. Am. Chem. Soc. 1958, 80, 4, 832–835Publication Date (Print):February 1, 1958Publication History Published online1 May 2002Published inissue 1 February 1958https://doi.org/10.1021/ja01537a020RIGHTS & PERMISSIONSArticle Views450Altmetric-Citations69LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (505 KB) Get e-Alerts Get e-Alerts

Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives1

Heat Stability Studies on Chelates from Schiff Bases of Salicylaldehyde Derivatives¹

Proteolytic activity of guinea pig serum activated by streptokinase-human plasminogen preparations.

The incubation of guinea pig serum with a streptokinase-human plasminogen preparation (from purified plasminogen) activates a proteolytic enzyme in the guinea pig serum. Optimal conditions for activity, kinetics, Km values and heat stability of elements of this system were studied. The proteolytic activity of this system was strongly inhibited by lysine ethyl ester and p-toluenesulfonylarginine methyl ester, apparently in a competitive manner. Serum dilution activity curves suggest the presence in guinea pig serum of dissociable protease inhibitors. The proteolytic activity of human plasmin does not appear to be essential for the activation of guinea pig protease, as indicated by heat stability studies. Possible mechanisms of activation are discussed. A survey of other animal species showed the widespread presence of serum proteases which could be activated with streptokinase-human plasminogen mixtures. The human activator systems may prove to be a useful tool in experimental studies of the physiological significance of the protease system.

Vinyl epoxystearate: Preparation, polymerization and properties of polymers and copolymers

AbstractVinyl epoxysterate was synthesized by the reaction of vinyl oleate and percarboxylic acids. An investigation of the kinetics of the epoxidation of the two unsaturated bonds in vinyl oleate showed that the epoxidation of the internal double bond proceeded at 220 times the rate of the vinyl bond. Polyvinyl epoxystearate was prepared by conventional methods. Like polyvinyl esters of other long‐chain fatty acids, polyvinyl epoxystearate exhibited low intrinsic and specific viscosities. The mechanical and thermal properties of copolymers of vinyl chloride and vinyl epoxystearate were compared with those of compositions of polyvinyl chloride and butyl epoxystearate. Vinyl epoxystearate had a greater effect of the milling temperature of the copolymer than butyl epoxystearate had on that of the composition, but the opposite effect was observed on the temperature coefficient of the torsional modulus. In heat and light stability studies, it was found that butyl epoxystearate (or other external epoxy plasticizers) was more efficient than vinyl epoxystearate.

Heat stability studies on clotting factors in thromboplastic preparations.

Summary1. On the basis of heat stability studies, the clotting properties of brain tissue extracts are due to 2 components: a) a throm-bokinase, which has the ability to convert prothrombin directly to thrombin, and b) a thromboplastin, which is an accessory factor and must react first with another plasma factor, such as proconvertin, before it is capable of converting prothrombin to thrombin. 2. The indirect effect of thromboplastin must be distinguished from the direct action of thrombokinase on prothrombin if the mode of action of so-called “thromboplastin” brain tissue extracts is to be understood.

Variation in Influenza Viruses. A Study of Heat Stability of the Red Cell Agglutinating Factor.

SummaryA report has been made of the observation of variation among different strains and different lines of the same strain of influenza virus with respect to the heat-stability of the hemagglutinating property. Certain theoretical and practical implications of this observation have been discussed.