bluuebunny/crossref_metadata_2025 huggingface dataset:
CHANGES PRODUCED BY PROTEIN MALNUTRITION ON THE CONCENTRATION OF DEOXYRIBONUCLEIC ACID IN HUMAN LIVER
Authors: Umaña Roberto
Published: December 2009

The content of deoxyribonucleic acid of samples of liver obtained from children at autopsy under standardized conditions was determined. There were higher concentrations in the livers of malnourished children, but there was not a significant difference associated with a distinction between kwashiorkor and marasmus.
THE IDENTIFICATION OF DIMETHYL-β-PROPIOTHETIN IN THE ALGAE SYRACOSPHAERA CARTERAE AND ULVA LACTUCA
Authors: Tocher C. S. , Ackman R. G. , McLachlan J.
Published: December 2009

Dimethyl-β-propiothetin (DMPT) has been reported to be present in some species of unicellular phytoplankton on the basis of the evolution of dimethyl sulfide (DMS), one of its breakdown products. The presence of DMPT in Syracosphaera carterae has now been confirmed by precipitation of it as the reineckate, with recovery and chromatographic analyses by paper and thin-layer techniques. Multicellular Ulva lactuca, which is known to contain DMPT, was used as a control. All steps were monitored by the gas–liquid chromatographic procedure for measuring DMS. Chromatograms were run in four solvent systems. All parts of the chromatograms were eluted, and tested for DMS. The only portion of any chromatogram that yielded DMS was that area corresponding to the RFvalue of authentic DMPT.
EFFECTS OF STARCH CONCENTRATION ON THE RESOLUTION OF SERUM PROTEINS BY GEL ELECTROPHORESIS: A SIX-SPECIES COMPARISON
Authors: Krotoski W. A. , Benjamin D. C. , Weimer H. E.
Published: December 2009

The effects of starch concentration on the resolution of serum components by gel electrophoresis were investigated. Gels were prepared with starch contents varying from 11.8 to 20.6% (w/v). Pooled serum samples from man, rabbit, guinea pig, rat, mouse, and chicken were separated by vertical and two-dimensional electrophoresis in the discontinuous Tris–citrate and borate system of buffers. The resolution of serum components at the various starch levels was compared with the results obtained with the standard concentration (11.8%) recommended for separation in human serum. A general increase in the number of bands staining for protein was observed in gels with starch concentrations between 13.0 and 16.0%, although species differences were observed in regard to optimum starch concentrations. The maximum number of serum proteins detected by one-dimensional electrophoresis were, for the various species: man, 27; rabbit, 15; guinea pig, 22; rat, 21; mouse, 19; and chicken, 12.
ISOLATION OF THE EPITHELIAL CELLS OF THE RAT SMALL INTESTINE
Authors: Perris A. D.
Published: December 2009

A new method for the preparation of isolated intestinal epithelial cells from the rat is described. Suspensions of these cells respire actively, taking up oxygen in a linear relationship with time for about 40 minutes. When actively transported sugars are present in the incubation medium, the cells utilize more oxygen. It is suggested that such preparations may be useful in the study of intestinal function at the cellular level.
STRUCTURAL CHANGES ASSOCIATED WITH THE RELEASE OF ENZYMES FROM RAT-LIVER MITOCHONDRIA BY FREEZING
Authors: Lusena C. V. , Dass C. M. S.
Published: December 2009

Suspensions of rat-liver mitochondria in 0.44 M sucrose, after they were frozen and thawed under defined conditions, were partitioned into three sedimentable and one supernatant fraction by differential centrifugation. These were analyzed for optical density, protein content, and for activities of glutamate dehydrogenase (GD) and 3-hydroxybutyrate dehydrogenase (BD) with exogenous nicotinamide–adenine dinucleotide (NAD) both as maximum activity after sodium deoxycholate treatment and as activity released by freezing. Pellets of the three sedimentable fractions were also examined in the electron microscope. When dehydrogenases were not released by a freezing treatment, no structural changes were detected. Release of BD, which was accompanied by release of GD as well, was associated with mitochondrial disruption and drastic rearrangement of mitochondrial membranes. On the other hand, release of GD without BD occurred from swollen and emptied mitochondria. The partial release of enzymes in a preparation was not associated with a partial structural modification of all of the mitochondria, but rather with drastic structural changes in only some of them.
THE EFFECT OF PARATHION ON THE LIVER AND KIDNEY CARBOXYLESTERASES AND THE PLASMA ACETYLCHOLINESTERASES OF RATS FED NUTRITIONALLY DEFICIENT DIETS
Authors: Read Sheila I. , Middleton E. J. , Mckinley W. P.
Published: December 2009

Female rats were fed diets low in minerals, vitamins, or protein, or a control diet, both alone and supplemented with 10 parts per million (p.p.m.) parathion for 3 weeks. Male and female rats were fed control and tow-vitamin diets both with and without parathion supplementation (0–10 p.p.m.) for 3 weeks. The liver and kidney carboxylesterases (EC 3.1.1.1.), and the plasma acetylcholinesterases (EC 3.1.1.7.) of the male rats, were measured.In the female rats, a low-mineral diet resulted in an increase of carboxylesterases in the liver and kidney; a low-vitamin diet caused a marked increase in liver carboxylesterases but had no effect on the carboxylesterases of the kidney. Parathion at 10 p.p.m. in all diets greatly reduced the liver carboxylesterases but had less effect on kidney carboxylesterases, except in the case of the low-protein diet, for which the reduction was similar to that in the liver. Varying amounts of parathion added to the low-vitamin diet reduced the liver and kidney carboxylesterases, but to a less extent than when added to the control diet.The liver carboxylesterases of male rats were inhibited approximately 50% by 2 p.p.m. parathion in the control diet and by 4 p.p.m. parathion in the low-vitamin diet. However, inhibition of plasma acetylcholinesterase and kidney carboxylesterases was not marked until the 10 p.p.m. parathion level was fed. The acetylcholinesterase activity of the plasma of male rats did not decrease until the level of liver carboxylesterases was very low.
LIPOAMINO ACIDS: SYNTHESIS OF AMINO ACID ESTERS OF PHOSPHATIDYL GLYCEROLS
Authors: Baer Erich , Rao K. V. Jagannadha
Published: December 2009

The synthesis of α′-glycine and α′-alanine esters of α-(L-α-phosphatidyl)glycerols with myristic acid, palmitic acid, and stearic acid substituents is described. The lipoamino acids were obtained by the simultaneous phosphorylation of a D-α,β-diglyceride and azidoacyl β-benzyl glycerol with phenylphosphoryl dichloride and pyridine, isolation of the (diacyl L-α-glyceryl), (azidoacyl β-benzylglyceryl)-phenylphosphate by column chromatography on silicic acid, and the removal of the protective phenyl and benzyl groups as well as the reduction of the azido to the amino group in one operation by catalytic hydrogenolysis with a mixture of palladium and platinum catalysts.Azidoacetyl β-benzyl glycerol and 2-azidopropionyl β-benzyl glycerol were prepared by acylating β-benzyl glycerol with azidoacetyl chloride and 2-azidopropionyl chloride, respectively, and separating the mixtures of azidoacyl and bis-azidoacyl β-benzyl glycerols by column chromatography on silicic acid.
INHIBITION OF YEAST METABOLISM BY 2-DEOXYGLUCOSE, 6-DEOXY-6-FLUOROGLUCOSE AND THE CORRESPONDING GALACTOSE DERIVATIVES
Authors: Blakley E. R. , Myoda T. , Spencer J. F. T.
Published: December 2009

The inhibitory effects of 2-deoxy-D-glucose (2DG) and 6-deoxy-6-fluoro-D-glucose (6FG) on the metabolism of glucose by yeast were compared and some properties of the glucose transport system were examined. 2DG and 6FG had similar effects on the consumption of oxygen and the production of carbon dioxide by several strains of yeast, hence they appear to inhibit metabolism of glucose by the same mechanism. Kinetic studies with mixed inhibitors indicated that both compounds compete at the same catalytic site. The rate of entry of 6FG into the yeast cell and its equilibrium concentration were similar to those of galactose. The fermentation of D-galactose was strongly inhibited by 2DG and 6FG, and weakly inhibited by 2-deoxy-D-galactose and 6-deoxy-6-fluoro-D-galactose. The latter two compounds did not inhibit the fermentation of D-glucose.
THE ANALYSIS OF NEUTRAL GLYCOSES IN BIOLOGICAL MATERIALS BY GAS–LIQUID PARTITION CHROMATOGRAPHY
Authors: Morrison I. M. , Perry M. B.
Published: December 2009

A new method for the determination and characterization of neutral aldoses is presented. The method involves the oxidation of aldoses with hypoiodite or hypobromite to their corresponding aldonic acids which, after conversion to their 1,4-lactones, are treated with pyridine–trimethylchlorosilane–hexamethyl-disilazane mixtures to yield the O-(trimethylsilyl)-aldono-1,4-lactone derivatives. These derivatives are sufficiently stable and volatile to allow their separation and quantitative analysis to be made by gas–liquid partition chromatography (g.l.p.c).The procedure was successfully applied to the analysis of mixtures of aldopentoses, aldohexoses, and aldoheptoses and was found to provide a rapid and accurate method for the quantitative analysis of the glycoses commonly occurring in natural glycans. Preparative g.l.p.c. yielded samples of the individual O-(trimethylsilyl)-aldono-1,4-lactones which had characteristic specific optical rotations, infrared spectra, and g.l.p.c. retention times. Comparison of the properties of the authentic O-(trimethylsilyl)-aldono-1,4-lactones with derivatives prepared from the original glycoses found in the hydrolysates of natural glycans permitted a positive identification of the component glycoses to be made on a microscale.
RELATION OF THE METABOLISM OF PIGEON-MUSCLE MITOCHONDRIA TO THE NET UPTAKE OF POTASSIUM AND ITS SELECTION OVER SODIUM
Authors: Marcus G. J. , Manery J. F. , Dryden E. E.
Published: December 2009

Three processes (cation accumulation, rate of oxidation, and rate of phosphorylation) were measured on each of the mitochondrial preparations made from pigeon-breast muscle. Mitochondria were incubated for 30 minutes in media containing ATP, a hexokinase–glucose acceptor system, and sodium and potassium in the ratio of 1:1. Variation in metabolic rate was achieved by using α-ketoglutarate, α-ketoglutarate + muscle supernatant, malate, or β-hydroxy-butyrate as substrates. The mitochondria and the media were analyzed before and after incubation so that accurate concentration gradients could be calculated. When α-ketoglutarate was substrate, a small but highly significant net uptake of potassium and an increased potassium gradient were found. The change in sodium was statistically insignificant, showing selection of potassium over sodium. Only in β-hydroxybutyrate, where the rates of respiration and phosphorylation were low, was there a net uptake of sodium as well as potassium so that no cation selection was apparent.
ACID-SOLUBLE SULFHYDRYL COMPOUNDS IN L-CELLS DURING VARIOUS CONDITIONS OF GROWTH
Authors: Sparkes B. G. , Walker I. G.
Published: December 2009

During exponential growth of suspension cultures of L-cells, the intracellular concentration of acid-soluble sulfhydryl compounds varied in a characteristic fashion. In a freshly diluted culture, the concentration rose to a maximum but as the population density increased, the concentration fell. This effect was attributed to inadequate cultural conditions; either a needed substance became limiting or an undesirable substance accumulated. Thus, if the culture was diluted frequently to approximate chemostatic conditions, the concentration remained at a high and constant level. When cell division was inhibited by 5-fluorodeoxyuridine, the level of acid-soluble sulfhydryl compounds increased but the extent of the increase again depended on the age of the culture, with a freshly diluted culture showing a maximum increase. Several other cellular constituents as well as the cellular volume also exhibited these patterns. The major sulfhydryl and disulfide components in the cell were reduced and oxidized glutathione. Only traces of cysteine and two unidentified sulfhydryl compounds were present. Cell growth in medium lacking glutathione was completely normal. In addition, the cysteine in the medium was found to be completely oxidized. Thus, the cells have mechanisms which enable them to obtain their cysteine requirements from the cystine in the medium, to synthesize glutathione de novo, and to maintain a reduced-plus-oxidized glutathione balance and at the same time maintain a very small pool of cysteine and (or) cystine.
HETEROGENEITY OF INSULIN: I. ISOLATION OF A CHROMATOGRAPHICALLY PURIFIED, HIGH-POTENCY INSULIN AND SOME OF ITS PROPERTIES
Authors: Dillon W. W. , Romans R. G.
Published: December 2009

A slight improvement in the chromatography of insulin on Amberlite IRC-50 resin in 7 M urea −0.13 M sodium phosphate buffer, pH 6.05, at 3 °C revealed the presence of at least four components.The major component was found to have a potency greater than that of any other purified insulin hitherto reported and substantiated. The biological activity of the minor components varied from a value close to that of the starting insulin down to very low or negligible values, indicating a loss of biological activity with increasing chemical degradation. The potency studies were quantitative.Starch-gel electrophoresis showed that the main component was not completely homogeneous, traces of other components being present.A highly fluorescent, colored material was separated from among the minor components and may be of interest in relation to allergy produced by some insulins.The separation reported here is discussed in relation to other fractionation procedures.
STEROIDS AND STEROIDASES: II. A GENERAL GAS-LIQUID CHROMATOGRAPHIC ASSAY FOR STEROIDASES AND ITS APPLICATION TO THE C-1,2-DEHYDROGENASE OF BACILLUS SPHAERICUS
Authors: Jones J. Bryan , Vlasinich Vesna , Leman Jeffrey D.
Published: December 2009

A gas–liquid chromatographic method was developed which is suitable for the preliminary assay of steroidases contained in wholly unrefined preparations. Its scope was illustrated by application to the Δ1-dehydrogenase of Bacillus sphaericus. Progesterone induction of B. sphaericus resulted in a sixfold increase in Δ1-dehydrogenase activity, and the enzyme was found to be stable indefinitely when the B. sphaericus preparations were stored as acetone powders at −20°. The pH dependence of the enzyme showed a maximum at 7.5. The optimum concentration of the electron acceptor used, menadione, was also determined.
PERIPHERAL INTERCONVERSION OF PHENOLIC STEROIDS IN THE HUMAN
Authors: Hobkirk R. , Nilsen Mona , Purre Ene
Published: December 2009

A tracer dose of estradiol-17β-6,7-3H was injected intravenously into male subjects simultaneously with a14C-labeled steroid. The latter was either 16-ketoestradiol-17β-16-14C, 16-epiestriol-16-14C, or estriol-16-14C. All eight urinary metabolites of estradiol-17β-3H studied, and the main metabolites of the 16-oxygenated steroids, were predominantly split by β-glucuronidase hydrolysis. The major urinary metabolite released by solvolysis was estrone, as a conversion product of estradiol-17β-3H. After injection of estradiol-17β-3H together with either 16-ketoestradiol-17β-14C or 16-epiestriol-14C, urinary 16β-hydroxyestrone contained both isotopes. 16α-Hydroxyestrone, on the other hand, contained3H but only insignificant amounts of14C. This suggests formation of 16β-hydroxy-estrone but not 16α-hydroxyestrone from these injected 16-oxygenated steroids. 16-Epiestriol was metabolized to identifiable urinary metabolites to a considerably greater degree than was estriol. This was confirmed in a further experiment in which only 16-epiestriol-14C was injected.
HYDROLASES AND DEHYDROGENASES OF CHICKEN TISSUES
Authors: Ecobichon D. J.
Published: December 2009

Proteins in aqueous extracts of breast muscle, leg muscle, cardiac muscle, liver, kidney, and spleen of adult cockerels were compared by zone electrophoresis in starch gel in sodium cacodylate or sodium citrate – phosphate systems. The proteins and enzymes were located in the starch gel by a variety of histochemical techniques. A partial characterization of the tissue esterases was carried out with various substrates and specific inhibitors. The 18 bands of esterases detected in tissues were aliesterases of two different types. Tissue specific enzymic patterns were obtained for esterases, alkaline phosphatase, acid phosphatase, lactate dehydrogenase, malate dehydrogenase, and isocitrate dehydrogenase. Glutamate dehydrogenase and glucose-6-phosphate dehydrogenase activity were detected only in the liver and kidney.
ON THE FORMATION OF TESTOSTERONE BY THE PERFUSED RABBIT TESTIS
Authors: Ewing Larry L. , Eik-Nes Kristen B.
Published: December 2009

The results of this investigation have proven the feasibility of using a perfusion method in vitro to demonstrate testosterone biosynthesis and secretion in the rabbit testis. It has been shown that (i) accumulation of testosterone in the venous effluent of the perfused testis was the result of biosynthesis and secretion of this compound rather than passive leakage from the organ; (ii) integrity of the enzymes involved in testosterone biosynthesis were maintained during perfusion for up to 7 hours; (iii) secretion rate of testosterone in this system was independent of testis size, venous blood flow, and glucose supply to the testis; (iv) both acetate-1-14C and cholesterol-7α-3H were incorporated into testosterone; (v) no solubilizing agents were needed in this preparation for the biotransformation of cholesterol-7α-3H to test.osterone-3H; (vi) addition of human chorionic gonadotrophin (HCG) or interstitial cell stimulating hormone (ICSH) to the perfusate resulted in increased testosterone secretion and alterations in rates of incorporation of acetate-1-14C and cholesterol-7α-3H into testosterone; (vii) slices of rabbit testis produced radioactive testosterone when incubated with cholesterol-7α-3H and acetate-1-14C, and when gonadotrophins were added to such incubations, the specific radioactivity of testosterone-14C increased whereas that of testosterone-3H decreased; and (viii) the interstitial cell stimulating hormone may have its predominant effect in promoting biosynthesis of cholesterol from acetate both in perfused and in slices of rabbit testis.
EXCRETION OF BILE ACIDS BY THREE MEN ON CORN OIL AND BUTTERFAT DIETS
Authors: Ali S. S. , Kuksis A. , Beveridge J. M. R.
Published: December 2009

The excretion of fecal bile acids was determined in three adult males during the last 4 days of eight dietary periods of 8 days each, during which 35 to 60% of total calories was provided by corn oil or butterfat. The bile acids were identified and individually estimated by a combination of thin-layer and gas chromatography. The total output in two subjects on butterfat (three samples) was 165–288 mg/day, whereas a third subject on a similar diet (two samples) excreted only 38–57 mg/day. On corn oil, the latter subject excreted 37 mg/day of total fecal bile acid and, on mixed corn oil – butterfat diet, 120 mg/day. The low fecal bile acid output in this subject was comparable to that of one of the other two subjects (25 mg/day) on a hydrogenated corn oil diet. The qualitative fecal bile acid patterns were similar with both high-fat diets and resembled those observed earlier on fat-free regimens. Because of the large subject and sample variations, the significance of any quantitative differences in the fecal bile acid excretion with these diets remains in doubt.
NAPHTHOQUINONE BIOSYNTHESIS IN HIGHER PLANTS: I. STUDIES ON 2-HYDROXY-l,4-NAPHTHOQUINONE IN IMPATIENS BALSAMINA L.
Authors: Chen David , Bohm Bruce A.
Published: December 2009

The biosynthesis of 2-hydroxy-1,4-naphthoquinone in aerial portions of Impatiens balsamina L. (Balsaminaceae) has been studied. Phenylalanine-U-14C and sodium acetate-1-14C did not label the quinone. Shikimic acid-U-14C, however, was incorporated into the quinone with a dilution of 15.7. The conversion of shikimic acid to ferulic acid in these experiments was accomplished with a dilution of 39.6. GIucose-U-14C was incorporated into the naphthoquinone and ferulic acid molecules with dilutions of 9230 and 29,500 respectively. Administration of an excess of cold p-hydroxybenzoic acid along with labeled shikimic acid resulted in no incorporation of label into the quinone. Degradation of labeled 2-hydroxy-1,4-naphthoquinone yielded phthalic acid with 68.5% of the label originally in the quinone. This agrees well with the theoretical value of 67% calculated on the basis that the shikimic acid ring is incorporated intact into the quinone ring of 2-hydroxy-1,4-naphthoquinone.
INCORPORATION OF RADIOACTIVE COMPOUNDS INTO THE PURINE AND PYRIMIDINE BASES AND 2-DEOXYRIBOSE OF SALMON TESTES DEOXYRIBONUCLEIC ACID
Authors: Tars H. L. A. , Roy Joan
Published: December 2009

Slices of immature salmon testes incorporated radioactive purine and pyrimidine bases and related nucleosides, deoxynucleosides, nucleotides, and deoxynucleotides into deoxyribonucleic acid (DNA). When DNA was extracted from the tissues and hydrolyzed, the purine and pyrimidine bases obtained were labeled in a manner which suggested that the radioactive substrates had been incorporated into DNA by recognized biosynthetic pathways involving "preformed" purines and pyrimidines and their derivatives. Since radioactive carbonate, glycine, and formate were not incorporated into the purines obtained from DNA, and radioactive formate only caused labeling of the thymine, it would appear unlikely that the de novo biosynthesis of purine and pyrimidine rings occurs in milts. C-1, C-6, and generally labeled glucose-14C caused labeling of the 2-deoxyribose, but not of the purines or pyrimidines, of DNA. Radioactive adenylic acid, deoxyuridylic acid, ribose 5-phosphate, and 5-phospho-α-D-ribofuranosyl-1-pyrophosphate also caused labeling of the 2-deoxyribose of DNA.
THE UTILIZATION OF AMMONIUM CHLORIDE-15N BY UREDOSPORES OF WHEAT STEM RUST
Authors: McConnell W. B. , Underhill E. W.
Published: December 2009

When uredospores of wheat stem rust, Puccinia graminis van tritici (race 15B), were incubated with a 3 mM solution of ammonium chloride-15N, a significant amount of nitrogen 15 was converted into organic nitrogen. Most of this organic nitrogen 15 was found in the ethanol and water extracts, with lesser amounts in the buffer and in extracted spores.Amino acids extracted from the spores all contained excess nitrogen 15. Nitrogen 15 from the inorganic source was diluted by factors of 1.7 and 2.7 in free aspartic and glutamic acids respectively; these amino acids were the most heavily labeled with the isotope. Proline was the most weakly labeled amino acid, the nitrogen 15 being diluted by a factor of 102. Good incorporation of nitrogen 15 into glutamic acid compared to simultaneous poor incorporation into the biochemically related amino acid, proline, parallels previous observations made during carbon 14 experiments with rust uredospores.Fourteen "bound" amino acids were isolated after acid hydrolysis of extracted spores. All contained nitrogen 15, the dilution of the added ammonia nitrogen ranging from 96 for glutamic acid to 7660 for proline.The results are taken as evidence that uredospores of wheat stem rust can incorporate ammonium nitrogen into free amino acids and into proteins.
REGULATION OF THE INITIATION OF HEMOGLOBIN SYNTHESIS IN THE BLOOD ISLAND CELLS OF CHICK EMBRYOS: I. QUALITATIVE STUDIES OF THE EFFECTS OF ACTINOMYCIN AND δ-AMINOLEVULINIC ACID
Authors: Wainwright S. D. , Wainwright Lillian K.
Published: December 2009

Intact and de-embryonated blastodiscs of chick embryos from all stages of development between the definitive primitive streak and the 10-somite stage were incubated on simple solid synthetic media. On the basal medium, blastodiscs at all initial stages of development synthesized hemoglobin readily visible to the naked eye within 24 hours, incorporated leucine into protein at an approximately linear rate for 24 hours, and incorporated uridine into RNA at a roughly linear rate for at least 6 hours after a short lag.Blastodiscs taken before the 1-somite stage failed to synthesize any detectable hemoglobin on medium containing 2 μg/ml of actinomycin, whereas those token at later stages synthesized hemoglobin visible to the naked eye. This concentration of actinomycin totally inhibited the incorporation of uridine into high molecular weight RNA within 2–3 hours, but the incorporation of leucine into protein was not inhibited for 6–8 hours. The residual incorporation of uridine was entirely into the soluble RNA fraction.At 10 μg/ml, actinomycin markedly inhibited the synthesis of hemoglobin by blastodiscs taken at stages earlier than the 6-somite embryo, but did not markedly affect hemoglobin synthesis by the more advanced blastodiscs. This concentration of actinomycin caused only slightly greater inhibition of the incorporation of uridine into acid-precipitable material than the smaller concentration for all blastodiscs, and was not markedly more inhibitory for the incorporation of leucine into protein.The presence of δ-aminolevulinic acid overcame the inhibitions of synthesis of hemoglobin by actinomycin but did not prevent the inhibitions of incorporation of uridine into RNA and of leucine into protein.Regulation of the onset of rapid hemoglobin synthesis appears to be at the translation level, probably through the supply of δ-aminolevulinic acid. The latter is probably regulated through synthesis of RNAs formed at the head-fold stage. Messenger RNAs for globin synthesis are present at the stage of the definitive primitive streak.
A GENERAL METHOD FOR THE ISOLATION AND PURIFICATION OF PHOSVITIN FROM VERTEBRATE EGGS
Authors: Wallace R. A. , Jared D. W. , Eisen A. Z.
Published: December 2009

A general method has been developed for the isolation and purification of phosvitin from vertebrate eggs. The method is detailed in three steps consisting of (i) isolation of a phosvitin–lipovitellin complex; (ii) ammonium sulfate precipitation of the lipovitellin; and (iii) DEAE-cellulose chromatography of the remaining phosvitin. Phosvitin was isolated from the eggs of five representative vertebrates (lamprey, trout, frog, turtle, and chicken), and chemical analyses together with sedimentation studies were performed on the samples. Preparations were obtained with the lowest N/P ratios reported to date. The analytical results also suggested that trout phosvitin has approximately half the molecular weight (24,000) of the other proteins and that "purified" phosvitin may still be heterogeneous.
END-PRODUCT INHIBITION OF THREONINE DEAMINASE OF STREPTOMYCIN MUTANTS OF ESCHERICHIA COLI K-12
Authors: Desai I. D. , Polglase W. J.
Published: December 2009

In the presence of end product (L-isoleucine), the biosynthetic threonine deaminase in extracts of streptomycin mutants of Escherichia coli K-12 gave a sigmoid response to increasing substrate (L-threonine) concentration. The response to inhibitor at constant substrate concentration was similar. However, the mutants showed quantitative differences in the "threshold" concentration of effector (substrate or inhibitor) required to produce the response. The smallest threshold was observed with the wild-type (streptomycin-sensitive) strain and the largest threshold with the streptomycin-resistant (indifferent) strain. The streptomycin-dependent strain was intermediate. The differences in response to effector may be caused by structural differences at the sites of bonding between subunits of the enzyme protein.These observations on feedback regulation, together with previous observations on repression in streptomycin mutants, indicate that the effects of the antibiotic are directed towards enzymes which perform a regulatory function.
BLOOD AMINO ACID STUDIES: VI. USE OF PLASMA AMINO ACID SCORE FOR PREDICTING LIMITING AMINO ACID(S) IN DIETARY PROTEINS
Authors: McLaughlan J. M. , Rao S. Venkat , Noel F. J. , Morrison A. B.
Published: December 2009

Male weanling rats were offered diets ad libitum 18 hours daily for 4–7 days. Protein sources included whole wheat, oatmeal, corn, rye, rice, millet, pea, soya, chick-pea, lentil, lima bean, navy bean, cottonseed, peanut, sesame, egg, fish, milk, and mixtures of animal and plant proteins. Levels of plasma lysine, methionine, threonine, tryptophan, leucine, and isoleucine were determined, and plasma amino acid (PAA) scores were calculated. The limiting amino acid(s) in each diet according to PAA score was in good agreement with that reported in the literature. These data provide convincing evidence that plasma amino acid levels can be used to determine the limiting amino acid in practical diets.
THE INCORPORATION OF α-GLYCEROPHOSPHATE-32P INTO THE LIPIDS OF RAT BRAIN PREPARATIONS: II. ON THE BIOSYNTHESIS OF MONOPHOSPHOINOSITIDE
Authors: Possmayer F. , Strickland K. P.
Published: December 2009

Previous investigations conducted in this laboratory showed a number of differences in the cytosine nucleotide requirement for the incorporation of α-glycerophosphate (α-G32P) into the monophosphoinositide of rat brain preparations compared to the pathway described by Paulus and Kennedy, where α-glycerophosphate → phosphatide acid → CDP-diglyceride → monophosphoinositide, and CTP is specifically required. Experiments were carried out with rat brain preparations to determine the nature of the mechanism whereby CDP-choline is as effective as or more effective than CTP in stimulating the incorporation of α-G32P into monophosphoinositide. Isotope dilution experiments in which unlabeled phosphatidic acid and CDP-diglyceride were used, yielded results consistent with the view that both of these compounds are intermediates in the incorporation of a-G32P into monophosphoinositide stimulated by either CTP or CDP-choline. Time-course experiments where cytosine nucleotides were added either at the beginning or after 20 minutes produced a pattern of labeling which could be fitted into the above interpretation, provided that newly formed radioactive molecules of phosphatide acid could be used selectively and CTP in some way inhibits phosphatide acid formation or accumulation. The latter could account for the observation that monophosphoinositide becomes far more actively labeled than phosphatidic acid in the presence of added CTP.
MECHANISM OF METOPIRONE INHIBITION OF A SOLUBLE ADRENAL STEROID 11β-HYDROXYLASE
Authors: Williamson Denis G. , O'Donnell Vincent J.
Published: December 2009

The effect of Metopirone (2-methyl-1,2-bis(3-pyridyl)-1-propanone) (Su-4885) on the 11β-hydroxylation of 11-deoxycorticosterone (DOC) and NADPH oxidation has been examined in a soluble enzyme system extracted from an acetone powder of bovine adrenal mitochondria. Addition of Metopirone in the absence of DOC stimulated the oxidation of reduced nicotinamide–adenine dinucleotide phosphate (NADPH) by the enzyme system. Under the experimental conditions employed, 11β-hydroxylation was inhibited 50% by Metopirone at a final concentration of 4.2 μmoles/l, a quantity 27 times less than that required to produce a twofold increase in NADPH oxidation in the absence of DOC. Low levels of Metopirone that effectively inhibited corticosterone formation produced a similar decrease in NADPH oxidation associated with the hydroxylation reaction, indicating the interrelationship of 11β-hydroxylation and NADPH oxidation. Evaluation of kinetic data showed that the inhibition of 11β-hydroxylation produced by Metopirone was competitive. The Kmfor the 11β-hydroxylation of DOC was 1.8 × 10−5 mole/l and the Kifor Metopirone was 3.2 × 10−7 mole/l. The ratio Km:Kiindicated that the affinity of Metopirone for the 11β-hydroxylase was 56 times greater than that of DOC.
THE LIPIDS OF LIPOMYCES LIPOFER
Authors: McElroy Frances A. , Stewart H. B.
Published: December 2009

As a preliminary to the study of lipid synthesis in Lipomyces lipofer, the nature of the lipid accumulated by this organism was investigated. Neutral lipids were found to predominate, especially in older cultures of high lipid content. The triglyceride fraction was the major component, with smaller quantities of hydrocarbon, free and esterified ergosterol, monoglyceride, diglyceride, and free fatty acid also present. Phosphatid-y-linositol constituted almost one-quarter of the phospholipid fraction. The phosphoglycerides of choline, serine and ethanolamine were also detected. Gas chromatographic evidence indicated that 16:0, 16:1, 18:0, 18:1, 18:2, 18:3 were the principal fatty acid components. The 18:1 fraction was shown by oxidative-cleavage studies to be primarily oleic acid. This fraction predominated, reaching a level of 69% of the total fatty acids in older cultures.
THE MECHANISM OF PYRIDINE NUCLEOTIDE SYNTHESIS IN EHRLICH ASCITES CARCINOMA AND HOST LIVER
Authors: Purko J. , Stewart H. B.
Published: December 2009

Labeled nicotinamide–adenine dinucleotide (NAD) and nicotinic acid–adenine dinucleotide (NacAD) were identified following Dowex 2 (formate) chromatography of extracts of Ehrlich ascites cells and of livers of mice 3 and 6 h after injection of nicotinamide (Nam) (500 mg/kg) containing Nam-7-14C, and 3 h after injection of nicotinic acid (Nac) (50 mg/kg) containing Nac-7-14C into tumor-bearing animals. Labeled Nac mononucleotide (NacMN) was also identified in the liver extracts. The urinary metabolic products of the precursors were separated and partially characterized. Liver appeared to be somewhat more active in synthesis of NAD than tumor; the more efficient amidation of NacAD to NAD in liver probably contributes to this difference. The results are consistent with NacAD being an intermediate in NAD biosynthesis. Investigations of extracts of acetone powders of tumor provided evidence for two possible routes of synthesis (via NMN, and NacMN–NacAD): (1) Extracts incubated with Nam mononucleotide (NMN) and ATP formed NAD. (2) Extracts incubated with Nac-14C or Nam-14C with suitable supplementation gave rise to labeled NacMN, NacAD and NAD. These substances were isolated and their specific activities determined. Glutamine appeared to enhance NAD formation at the expense of NacAD. Although a net accumulation of NAD did not occur, the formation of Nam-14C from Nac-14C and the demonstration of NADase in the preparations suggested that NAD was formed but rapidly degraded.
FRACTIONATION ON DEAE-SEPHADEX OF NORMAL AND A-MYELOMA HUMAN SERA: I. ELECTROPHORETIC HETEROGENEITY OF γA GLOBULINS
Authors: Perelmutter L. , Goodfriend L.
Published: December 2009

DEAE-Sephadex chromatography was employed to fractionate the γA globulins of normal and A-myeloma human sera. By immunoelectrophoresis, the normal γA globulins had mobilities ranging from that of γ1to α2globulins, whereas the myeloma γA globulins were of essentially uniform mobility. Most of the normal γA globulins were homogeneous with respect to sedimentation in a sucrose density gradient, indicating that their immunoelectrophoretic heterogeneity was due largely to differences in molecular charge rather than size.
CATIONIC ANTIBIOTICS AND PHOSPHOLIPASE C AS TOOLS IN THE STUDY OF PHOSPHOLIPID STRUCTURE AND FUNCTION: I. INHIBITION OF THE IN VITRO CLOTTING SYSTEM BY CATIONIC ANTIBIOTICS
Authors: Ottolenghi Abramo C.
Published: December 2009

The one-stage prothrombin time of human plasma was prolonged by the addition to the thromboplastic mixture of either colistin sulfate or polymyxin B. Colistimethate sodium, a derivative of colistin in which the amino groups of the cyclic polypeptide antibiotic are substituted, did not show this effect. The inhibition was greater if the antibiotics were incubated with thromboplastin in the absence of Ca++. In the Hicks–Pitney modification of the thromboplastin generation time test, the two polyamine antibiotics reduced the amount of thromboplastic activity generated. Generation, however, appeared to be initiated sooner. It is postulated that these actions by the antibiotics are the results of modifications in the zeta potentials of the thromboplastic micelles.
A NON-NUCLEOTIDE POLYMER FOUND IN THE DNA OF THE SAND DOLLAR, ECHINARACHNIUS PARMA: I. ISOLATION
Authors: Rosenkranz Herbert S. , Garden III George A.
Published: December 2009

The deoxyribonucleic acid (DNA) isolated from the tissues of the adult sand dollar (Echinarachnius parma) contains a component of a buoyant density identical with that of polydeoxyadenylate-thymidylate. This material is resistant to thermal denaturation even when the heating procedure is carried out in the presence of formaldehyde. It is not digested by either ribonuclease or deoxyribonuclease. It can be purified by degrading the DNA with deoxyribonuclease and passing the digest through Sephadex G-100.
CYTOLYTIC ACTION OF CORTICOSTEROIDS ON THYMUS AND LYMPHOMA CELLS IN VITRO
Authors: Burton A. F. , Storr Judy M. , Dunn W. L.
Published: December 2009

Mouse and rat thymus cells can be maintained in good condition for up to 24 hours in tissue culture medium (Fischer's or 199) with serum or serum proteins, when aerated and incubated at 38 °C in stoppered tubes. Addition of corticosteroids produces cytolytic effects in nearly all cells, which are highly specific for those compounds having an 11β-hydroxyl group. Maximum effect occurs at concentrations of cortisol 0.27 μM, of dexamethasone 0.02 μM. Electron microscopy shows marked alteration at 2 hours with nuclear edema and disappearance of the normal chromatin pattern in treated cells, progressing to maximum at about 8 hours with disruption of nuclear and cell membranes. Steroid-sensitive mouse lymphosarcoma P1798 cells show similar changes, whereas those of the steroid-resistant subline do not. To demonstrate this action of corticosteroids at concentrations that are significant physiologically, the major difficulty is maintaining the cells in satisfactory condition. It is concluded that this effect of steroids is manifested only in cells that are intact and metabolically active, and might be independent of many other known biochemical changes produced by corticosteroids.
PARTICIPATION OF NICOTINAMIDE MONONUCLEOTIDE IN PYRIDINE NUCLEOTIDE SYNTHESIS IN TUMOR AND HOST LIVER
Authors: McDonald J. W. D. , Stewart H. B.
Published: December 2009

Evidence is presented to show that nicotinamide-7-14C in low or high doses is incorporated into nicotinamide mononucleotide (NMN) by Ehrlich ascites cells and host liver in vivo. Nicotinamide mononucleotide formed from nicotinamide-7-14C has been isolated from incubations of Sephadex-treated extracts of ascites cell acetone powders with 5-phosphoribosyl-1-pyrophosphate and characterized by spectral and chemical analysis. The apparent Kmand Vmaxfor NMN synthesis from nicotinamide have been determined. NMN-14C has been shown to form NAD-14C in the same extracts in the presence of ATP, and the apparent Vmaxand Kmof this process have been determined. The role of NMN in NAD synthesis is discussed.
NUCLEIC ACID METABOLISM IN INTESTINAL MUCOSA: V. HETEROGENEITY OF DEOXYRIBONUCLEIC ACID ISOLATED FROM THE INTESTINAL MUCOSA OF THE RAT
Authors: Mezei C. , Zbarsky S. H.
Published: December 2009

Doubly labeled DNA was isolated from the intestinal mucosa of rats injected intravenously with3H-thymidine and 24 hours later with14C-thymidine. The DNA was chromatographed on columns of methylated albumin–kieselguhr. The3H/14C ratios of the individual subfractions comprising the main DNA fraction eluted from the column increased from the earlier to the later sub-fractions in the DNA isolated from rats receiving the14C-labeled thymidine 20 minutes before they were killed. This result indicated a slower incorporation of the14C-labeled material into the DNA molecules represented by the later sub-fractions. In experiments in which the interval before the death of the animals was extended to 40 minutes, the3H/14C ratios were constant throughout the main DNA fraction. Enzymatic degradation of the doubly labeled DNA indicated that incorporation of both types of precursors had occurred well within the DNA molecule. Physical chemical differences were also detected among the subfractions. There appeared to be two main types of DNA which could be grouped according to thermal denaturation temperatures (Tm), and ultracentrifugation in cesium chloride gave evidence of differences in buoyant densities between the leading and final subfractions.
THE METABOLISM OF TRITIATED ESTRADIOL IN THE LAYING HEN
Authors: Hawkins R. A. , Taylor P. D.
Published: December 2009

The nature of the radioactive metabolites in the tissues of the laying hen soon after the intravenous administration of sub-microgram quantities of [6,7-3H]-estradiol has been examined by solvent partition and paper chromatography. Of the total radioactivity taken up by the tissue, the greatest proportion accountable for as free radio-steroid occurred in the follicle wall (81%), and the greatest proportion accountable for as conjugated radio-steroid was found in the bile (81%). The blood plasma contained approximately equal amounts of free (50%) and conjugated (47%) radio-steroid. The radioactive free steroid fraction of nearly all the tissues studied contained more than one compound, the composition ranging from nearly all estradiol (liver 86%) to virtually no estradiol (follicle wall 5%). In the follicle wall, an unidentified compound constituted a large proportion (83%) of the free radio-steroids; the possible identity of this metabolite is discussed. Labeled estrone was found in significant amounts only in the blood plasma.
THE EFFECTS OF IONS AND FREEZE–THAWING ON SUPERNATANT AND MITOCHONDRIAL MALATE DEHYDROGENASE
Authors: Blonde D. J. , Kresack E. J. , Kosicki G. W.
Published: December 2009

The effects of various ions added to the assay system for purified mitochondrial and supernatant pig-heart malate dehydrogenase have been studied. Phosphate, arsenate, and zinc ions strongly stimulate the mitochondrial enzyme. Phosphate and arsenate ions have little effect on the supernatant enzyme whereas zinc inhibits it. The stimulation by phosphate is relieved by the addition of magnesium ion, to the assay system.The effects on enzymatic activity were studied when the supernatant and mitochondrial malate dehydrogenase were subjected to freezing and thawing in various media. Freezing and thawing of the mitochondrial enzyme in Tris or citrate buffers with or without mercaptoethanol results in small activity loss. Supernatant malate dehydrogenase displays a marked loss in activity when frozen quickly in the presence of phosphate and mercaptoethanol; if mercaptoethanol is omitted, activity loss is small. NADH, oxalacetic acid (OAA), NAD, and malate protect against activity loss in the phosphate–mercaptoethanol system. Repeated freeze–thawing of mitochondrial malate dehydrogenase in the presence of both phosphate and magnesium results in extensive losses in activity. In all cases slow freezing produces little activity loss for either enzyme.
GANGLIOSIDES IN DEVELOPING RAT BRAIN: ISOLATION AND COMPOSITION OF SUBCELLULAR MEMBRANES ENRICHED IN GANGLIOSIDES
Authors: Spence M. W. , Wolfe L. S.
Published: December 2009

Neurones in the central nervous system of vertebrates contain considerable amounts of a complex group of acidic glycosphingolipids, the gangliosides. Determination of gangliosides, cholesterol, phospholipid phosphorus, neutral glycolipid hexose, and protein in developing rat brain showed that the deposition of gangliosides is predominantly a premyelin event. A light membrane fraction enriched in gangliosides relative to protein was obtained from neonatal rat-brain crude mitochondrial fractions by sucrose density-gradient centrifugations. Adult rat-brain fractions of similar density were not enriched in gangliosides because of the presence of myelin. If the initial homogenization and the separation of the crude mitochondrial fraction were carried out in 0.32 M sucrose at pH 9.2, the ganglioside enrichment of the light membrane fraction from both adult and neonatal rat brain was doubled. By further separation of the light membrane fraction on a second density gradient, particulate material was obtained from neonatal rat brain which consisted almost entirely of vesicular membrane elements. Based on dry weight, it contained gangliosides 7–9%, phospholipids 36–40%, cholesterol 5–7%, neutral glycolipids 1–3%, protein 28–29%, and cations (Na+, K+, Ca2+, Mg2+) 8%. This membrane fraction is likely derived from the neuronal plasma membrane or the endoplasmic reticulum.
EXCRETION OF PHOSPHOLIPIDS BY MEN ON HIGH FAT DIETS
Authors: Ali S. S. , Kuksis A.
Published: December 2009

The fecal excretion of phospholipids was determined in three adult males during the last 4 days of eight dietary periods of 8–16 days on high corn oil and butterfat diets (35–60% of calories from fat). The phospholipids were isolated, identified, and quantitatively estimated by a combination of column, thin-layer, and gas chromatographic techniques. On both high fat diets the chief components of the fecal phospholipid mixtures were tentatively identified as phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl choline, and phosphatidyl inositol. The output of total phospholipids in three subjects on butterfat ranged between 33 and 168 mg/day. Substitution of hydrogenated corn oil (45% of calories) and corn oil (60% of calories) for butterfat (35–60% of calories) led to increased excretion of phospholipids, 300 and 430 mg/day, respectively, for hydrogenated and refined corn oil. Addition of sitosterol to a butterfat diet also led to increased phospholipid output (208 mg/day), as did the mixing of butterfat and corn oil (180 mg/day). The changes in the total output of the phospholipids were accompanied by alterations in the proportions of the individual phospholipids as well as of the component fatty acids. It is concluded that the ingestion of corn oil or plant sterol leads to increased fecal output of phospholipids, when compared with butterfat and fat-free diets. A change in the activity or the population of the intestinal flora is suggested to explain this observation.
LE MÉTABOLISME DE LAL-, DE LAD- ET DE LADL-PHÉNYLALANINE CHEZ LE RAT
Authors: Godin Claude
Published: December 2009

Rats were injected with L-, D-, or DL-phenylalanine-1-14C. There was a lag period in the excretion of14C in respiratory CO2when D- or DL-phenylalanine was used compared with L-phenylalanine, but over a 24-hour period, the same quantity of14CO2was obtained from the three groups of rats. There was less radioactive phenylalanine and radioactive tyrosine incorporated into tissue proteins of rats injected with D-phenylalanine-1-14C 2 hours after injection. These rats also excreted slightly more radioactivity in their urine over the 24-hour period because of an increased excretion of phenylalanine and phenylpyruvic acid. The total quantity of radioactivity excreted in urine never exceeded 5% of the injected dose. This shows that L-, D-, and DL-phenylalanine are used very efficiently by the rat.
RESISTANCE TO PURINE RIBONUCLEOSIDE ANALOGUES IN AN ASCITES TUMOR
Authors: Caldwell Ian C. , Henderson J. Frank , Paterson A. R. P.
Published: December 2009

A tumor subline (EAC-R2) which is resistant to the growth-inhibitory effects of 6-(methylmercapto)purine ribonucleoside (Me6MPR) and formycin has been selected from the Ehrlich ascites carcinoma (EAC) by repeated administration of Me6MPR during the propagation of the tumor. Some biochemical characteristics of the two tumor lines have been compared.Cells of the EAC-R2 tumor could not form phosphorylated derivatives of Me6MPR and formycin, whereas these metabolites were readily formed by EAC cells. Extracts of the resistant cells could not convert Me6MPR to the 5′-phosphate, indicating that they were deficient in purine ribonucleoside kinase activity.Me6MPR, formycin, and several other purine nucleoside analogues produced much less inhibition of purine synthesis de novo in EAC-R2 cells than in the parent line of cells. However, adenine produced a similar degree of inhibition in both tumor lines, indicating that this pathway in the resistant variant is susceptible to feedback inhibition.It is proposed that a deficiency of purine ribonucleoside kinase(s) may be responsible for the inability of Me6MPR and formycin to inhibit the growth of the EAC-R2 tumor.