bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatty acid changes in liver and plasma lipid fractions after safflower oil was fed to rats deficient in essential fatty acids
Authors: Johnson R. R. , Bouchard P. , Tinoco J. , Lyman R. L.
Published: August 2015

1. Fatty acid patterns of liver and plasma triglycerides, phospholipids and cholesteryl esters were determined at intervals during 24hr. after essential fatty acid-deficient rats were given one feeding of linoleate (as safflower oil). 2. Liver triglyceride, phospholipid and cholesteryl ester fatty acid compositions did not change up to 7hr. after feeding. Between 7 and 10hr., linoleic acid began to increase in all fractions, but arachidonic acid did not begin to rise in the phospholipid until 14–19hr. after feeding. 3. Oleic acid and eicosatrienoic acid in liver phospholipid began to decline at about the time that linoleic acid increased, i.e. about 9hr. before arachidonic acid began to increase. 4. Changes in linoleic acid, arachidonic acid and eicosatrienoic acid in phosphatidylcholine resembled those of the total phospholipid. Phosphatidylethanolamine had a higher percentage content of arachidonic acid before the linoleate was given than did phosphatidylcholine, and after the linoleate was given the fatty acid composition of this fraction was little changed. 5. The behaviour of the plasma lipid fatty acids was similar to that of the liver lipids, with changes in linoleic acid, eicosatrienoic acid and arachidonic acid appearing at the same times as they occurred in the liver. 6. The results indicated that linoleic acid was preferentially incorporated into the liver phospholipid at the expense of eicosatrienoic acid and oleic acid. The decline in these fatty acids apparently resulted from their competition with linoleic acid for available sites in the phospholipids rather than from any direct replacement by arachidonic acid.
Studies on the biosynthesis of gramicidin S in a cell-free system from Bacillus brevis. Further attempts to elucidate its mechanism of synthesis
Authors: Figenschou K. J. , Frøholm L. O. , Laland S. G.
Published: August 2015

1. The pH optima for the incorporation of 14C-labelled amino acids into gramicidin S by an 11000g cell-free extract from Bacillus brevis have been determined. The pH optima for leucine, proline, phenylalanine, ornithine and valine were 7·5–7·7, 7·5–7·7, 7·7–7·9, 7·7–7·9 and 8·0–8·2 respectively. Hence the greatest difference in pH optima existed between leucine and valine, where it was 0·5pH unit. 2. The 11000g cell-free extract incorporated into gramicidin S only the l-isomers of valine, proline and ornithine. However, both isomers of leucine are utilized and the experiments indicate that a leucine racemase exists in the 11000g cell-free extract. With phenylalanine the l-isomer is utilized much more effectively than the d-isomer. This is noteworthy since it is the d-isomer that occurs in gramicidin S. The experiments indicate that conversion of the l-isomer into the d-form takes place at a stage beyond that of the free amino acid.
The relative significance of acetate and glucose as precursors for lipid synthesis in liver and adipose tissue from ruminants
Authors: Hanson R. W. , Ballard F. J.
Published: August 2015

1. The incorporation of labelled glucose into lipid by liver slices from sheep and cows is considerably less than that by liver slices from the rat, although oxidation to carbon dioxide occurs to a similar extent. ATP citrate lyase and NADP malate dehydrogenase are inactive in both sheep and cow liver but active in rat liver. The absence of the citrate-cleavage pathway of lipogenesis in ruminant liver has been confirmed by the negligible amounts of C-3 of aspartate incorporated into fatty acids. 2. Considerable amounts of [14C]acetate are incorporated into fatty acids and non-saponifiable lipid in rat and ruminant liver. Acetyl-CoA synthetase, the initial enzyme in the metabolism of acetate, has a high activity in liver from rat and ruminants. 3. In adipose tissue from ruminants more acetate than glucose is converted into lipids, whereas the converse is true in rat adipose tissue. The greater incorporation of [14C]acetate into fatty acids in adipose tissue from the ruminant as compared with the non-ruminant may be caused, in part, by the higher activity of acetyl-CoA synthetase activity in the ruminant. 4. The results suggest that, in both liver and adipose tissue from ruminants, acetate is a more important source of lipid than glucose. 5. Two enzymes of the hexose monophosphate shunt, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, are active in both tissues and from the three species.
The dimerization of Δ1-piperidine-2-carboxylic acid
Authors: Hope D B , Horncastle K. C. , Aplin R. T.
Published: August 2015

The l-amino acid oxidase of Mytilus edulis has been used to oxidize l-lysine on a large scale in the presence of catalase. The α-oxo acid derived from lysine cyclizes to a Schiff base, which readily dimerizes. The dimer undergoes spontaneous dehydration and decarboxylation to form 1,2,3,4,5,6,7,8-octahydropyrido[3,2-a]-indolizin-10(4bH)-one. This structure was established by a study of its molecular weight and infrared, nuclear-magnetic-resonance and mass spectra.
The hydrolysis of glycosyl fluorides by glycosidases
Authors: Barnett J. E. G. , Jarvis W. T. S. , Munday K A
Published: August 2015

1. α-d- and β-d-Glucopyranosyl, α-d- and β-d-galactopyranosyl, α-d-mannopyranosyl and α-d-xylopyranosyl fluorides were hydrolysed specifically by the respective glycosidases from several sources. 2. Use of specific inhibitors with a mixture of glycosidases from Helix pomatia intestinal juice showed that each glycosyl fluoride was hydrolysed only by the respective glycosidase. α-d-Glucopyranosidase and α-d-xylopyranosidase activities were shown to be due to different enzymes. 3. Partially purified enzyme preparations containing only one of the glycosidase activities hydrolysed only the corresponding glycosyl fluoride. 4. The configuration at C-1 of α-d-mannopyranosyl fluoride was confirmed since it was hydrolysed by an α-d-mannosidase preparation that contained no detectable β-d-mannosidase activity. 5. An attempt to prepare o-nitrophenyl β-d-mannopyranoside led only to o-nitrophenyl α-d-mannopyranoside.
Determination of the base composition of deoxyribonucleic acid by measurement of the adenine/guanine ratio
Authors: Kirk J. T. O.
Published: August 2015

A method is described for determination of the base composition (as guanine+cytosine or adenine+thymine content) of DNA by accurate measurement of the adenine/guanine ratio. The DNA is hydrolysed with 0·03n-hydrochloric acid for 40min. to release the purines. The hydrolysate is subjected to ion-exchange chromatography on Zeo-Karb 225. Apurinic acids are eluted with 0·03n-hydrochloric acid and then guanine and adenine are eluted separately with 2n-hydrochloric acid. Guanine and adenine are each collected as a single fraction, and the amount of base in each case is determined by measuring the volume and the extinction at suitable wavelengths. For use in the calculations, millimolar extinction coefficients in 2n-hydrochloric acid of 12·09 for adenine at 262mμ, and 10·77 for guanine at 248mμ, were determined with authentic samples of bases. The method gives extremely reproducible results: from 12 determinations with calf thymus DNA the adenine/guanine molar ratio had a standard deviation of 0·011; this corresponds to a standard deviation in guanine+cytosine content of 0·2% guanine+cytosine.
Regulation of development of hepatic glucokinase in the neonatal rat by the diet
Authors: Walker D G , Eaton Susan W.
Published: August 2015

1. Feeding a high-glucose diet to weanling rats showed that high hepatic glucokinase activities could be induced at 18 days of age, i.e. 2 days after development of the enzyme begins. 2. The normal development of glucokinase activity can be retarded by weaning rats on to carbohydrate-free, high-fat and high-protein diets. 3. Precocious development of the enzyme before 16 days of age cannot be induced by oral glucose administration. 4. It is concluded that the ability to synthesize glucokinase develops very rapidly and that the nature of the diet determines the normal developmental pattern.
Studies on the pathogenesis of liver necrosis by α-amanitin. Effect of α-amanitin on ribonucleic acid synthesis and on ribonucleic acid polymerase in mouse liver nuclei
Authors: Stirpe F. , Fiume L.
Published: August 2015

1. Injection of α-amanitin to mice causes a decreased incorporation of [6−14C]-orotic acid into liver RNA in vivo. 2. The activity of RNA polymerase activated by Mn2+ and ammonium sulphate is greatly impaired in liver nuclei isolated from mice poisoned with α-amanitin, and is inhibited by the addition of the same toxin in vitro. 3. The activity of the Mg2+-activated RNA polymerase is only slightly affected by α-amanitin either administered to mice or added in vitro.
The formation, distribution and function of ribosomes and microsomal membranes during induced amphibian metamorphosis
Authors: Tata J. R.
Published: August 2015

1. A lag period of about 4 days preceded the onset of metamorphosis precociously induced by tri-iodothyronine in tadpoles of the giant American bullfrog (Rana catesbeiana). It was established by the accelerated synthesis or induction of carbamoyl phosphate synthetase and cytochrome oxidase in the liver, serum albumin and adult haemoglobin in the blood, acid phosphatase in the tail, and the increase in the hindleg/tail length ratio. 2. A 4- to 6-fold stimulation, 2 days after the induction of metamorphosis, of the rate of synthesis of rapidly labelled nuclear RNA in liver cells was followed by an increasing amount of RNA appearing in the cytoplasm. Most of the newly formed RNA on induction of metamorphosis was of the ribosomal type. An accelerated turnover at early stages of development preceded a net accumulation of RNA in the cytoplasm, with no change in the amount of DNA per liver. 3. Most hepatic ribosomes of the pre-metamorphic tadpoles were present as 78s monomers and 100s dimers; metamorphosis caused a shift towards larger polysomal aggregates with newly formed ribosomes that were relatively more tightly bound to membranes of the endoplasmic reticulum. 4. The appearance of new polyribosomes in the cytoplasm on induction of metamorphosis was co-ordinated in time with a stimulation of synthesis of phospholipids of the smooth and rough endoplasmic reticulum, followed by a gradual shift in preponderance from the smooth to the rough type of microsomal membranes. 5. Electron- and optical-microscopic examination of intact hepatocytes revealed a striking change in the distribution and nature of ribosomes and microsomal membranes during metamorphosis. 6. Ribosomes prepared from non-metamorphosing and metamorphosing animals were identical in their sedimentation coefficients and in the structural ribosomal proteins. The base composition and sedimentation coefficients of ribosomal RNA were also identical. Induction of metamorphosis also did not alter the incorporation of 32P into the different phospholipid constituents of microsomal membranes. 7. Nascent 14C-labelled protein with the highest specific activity was recovered in the ‘heavy’ rough membrane fraction of microsomes, whereas little 14C was associated with ‘free’ polysomes. Protein synthesis in vivo was most markedly stimulated during metamorphosis in the tightly membrane-bound ribosomal fraction after the appearance of new ribosomes. 8. The rate of synthesis of macromolecules in vivo could not be followed beyond 7–8 days after induction because of variable shifts in precursor pools due to regression of larval tissues. 9. The stimulation of RNA and ribosome formation was specifically associated with the process of metamorphosis since no similar response to thyroid hormones occurred in those species (Axolotl and Necturus) in which the hormones failed to induce metamorphosis.
Synthesis of ribonucleic acid in normal bone in vitro
Authors: Steinberg James , Nichols George
Published: August 2015

1. The incorporation of [2−14C]uridine into nucleic acids of bone cells was studied in rat and pig trabecular-bone fragments surviving in vitro. 2. The rapid uptake of uridine into trichloroacetic acid-soluble material, and its subsequent incorporation into a crude nucleic acid fraction of bone or purified RNA extracted from isolated bone cells, was proportional to uridine concentration in the incubation medium over a range 0·5–20·0μm. 3. During continued exposure to radioactive uridine, bulk RNA became labelled in a curvilinear fashion. Radioactivity rapidly entered nuclear RNA, which approached its maximum specific activity by 2hr. of incubation; cytoplasmic RNA, and particularly microsomal RNA, was more slowly labelled. The kinetics of labelling and rapid decline of the nuclear/microsomal specific activity ratio were consistent with a precursor–product relationship. 4. Bulk RNA preparations were resolved by zonal centrifugation in sucrose density gradients into components with approximate sedimentation coefficients 28s, 18s and 4s. 5. Rapidly labelled RNA, predominantly nuclear in location, demonstrated a polydisperse sedimentation pattern that did not conform to the major types of stable cellular RNA. Material of highest specific activity, sedimenting in the 4–18s region and insoluble in 10% (w/v) sodium chloride, rapidly achieved its maximum activity during continued exposure to radioactive precursor and decayed equally rapidly during ‘chase’ incubation, exhibiting an average half-life of 4·3hr. 6. Ribosomal 28s and 18s RNA were of lower specific activity, which increased linearly for at least 6hr. in the continued presence of radioactive uridine. There was persistent but variable incorporation into ribosomal RNA during ‘chase’ incubation despite rapid decline in total radioactivity of the acid-soluble pool containing RNA precursors.
The structure and possible function of the glycolipid from Staphylococcus lactis I3
Authors: Brundish D E , Shaw N. , Baddiley J
Published: August 2015

1. The total lipid was extracted from Staphylococcus lactis I3 with chloroform–methanol mixtures and the glycolipid component was isolated by chromatography on silicic acid. 2. Saponification yielded a non-crystalline glycoside for which the structure O-β-d-glucopyranosyl-(1→6)-O-β-d-glucopyranosyl-(1→1)-d-glycerol has been established by chemical degradations and by comparison with synthetic material. 3. The role of the glycosyl diglycerides in bacterial membranes is discussed.
Carnitine and derivatives in rat tissues
Authors: Pearson D. J. , Tubbs P. K.
Published: August 2015

1. Free carnitine, acetylcarnitine, short-chain acylcarnitine and acid-insoluble carnitine (probably long-chain acylcarnitine) have been measured in rat tissues. 2. Starvation caused an increase in the proportion of carnitine that was acetylated in liver and kidney; at least in liver fat-feeding had the same effect, whereas a carbohydrate diet caused a very low acetylcarnitine content. 3. In heart, on the other hand, starvation did not cause an increase in the acetylcarnitine/carnitine ratio, whereas fat-feeding caused a decrease. The acetylcarnitine content of heart was diminished by alloxan-diabetes or a fatty diet, but not by re-feeding with carbohydrate. 4. Under conditions of increased fatty acid supply the acid-insoluble carnitine content was increased in heart, liver and kidney. 5. The acylation state of carnitine was capable of very rapid change. Concentrations of carnitine derivatives varied with different methods of obtaining tissue samples, and very little acid-insoluble carnitine was found in tissues of rats anaesthetized with Nembutal. In liver the acetylcarnitine (and acetyl-CoA) content decreased if freezing of tissue samples was delayed; in heart this caused an increase in acetylcarnitine. 6. Incubation of diaphragms with acetate or dl-β-hydroxybutyrate caused the acetylcarnitine content to become elevated. 7. Perfusion of hearts with fatty acids containing an even number of carbon atoms, dl-β-hydroxybutyrate or pyruvate resulted in increased contents of acetylcarnitine and acetyl-CoA. Accumulation of these acetyl compounds was prevented by the additional presence of propionate or pentanoate in the perfusion medium; this prevention was not due to extensive propionylation of CoA or carnitine. 8. Perfusion of hearts with palmitate caused a severalfold increase in the content of acid-insoluble carnitine; this increase did not occur when propionate was also present. 9. Comparison of the acetylation states of carnitine and CoA in perfused hearts suggests that the carnitine acetyltransferase reactants may remain near equilibrium despite wide variations in their steady-state concentrations. This is not the case with the citrate synthase reaction. It is suggested that the carnitine acetyltransferase system buffers the tissue content of acetyl-CoA against rapid changes.
Lactogenesis in the rat. Changes in metabolic parameters at parturition
Authors: Kuhn N. J. , Lowenstein J. M.
Published: August 2015

1. Tissue concentrations of nucleic acids, protein, fat, water, metabolites and lactose, and the activities of seven enzymes concerned in milk biosynthesis, were measured in the rat mammary gland at closely spaced times before, at and after parturition. 2. Changes are seen in the tissue concentrations of most substances, and several changes are initiated at least during the day preceding parturition. 3. Lactose, which is absent 1 day before parturition, is found in amounts of 12μmoles/g. fresh wt. of tissue at parturition. 4. From the tissue activities before parturition of three enzymes on the biosynthetic pathway of lactose, and, from the small changes observed in their activities at parturition itself, it is concluded that the factors responsible for the appearance of lactose at parturition remain to be demonstrated.
The metabolism of dipotassium 2-hydroxy-5-nitrophenyl [35S]sulphate, a substrate for lysosomal arylsulphatases A and B
Authors: Flynn T. G. , Dodgson K S , Powell G M , Rose F A
Published: August 2015

The metabolic fate of dipotassium 2-hydroxy-5-nitrophenyl [35S]sulphate ([35S]NCS), a chromogenic substrate for lysosomal arylsulphatases A and B, has been studied in rats. Intraperitoneal injection of [35S]NCS into free-ranging animals is followed by excretion of the bulk of the radioactivity in the urine within 24hr., less than 13% being eliminated as inorganic [35S]sulphate. Most of the urinary radioactivity can be accounted for as [35S]NCS, but small amounts of a labelled metabolite are also present. Experiments in which [35S]NCS was injected intravenously into anaesthetized rats with bile-duct and bladder cannulae confirm that the ester is rapidly excreted in the urine. However, small amounts of radioactivity appear in bile, mainly in the form of the metabolite detected in urine. When [35S]NCS is perfused through the isolated rat liver, about 35% of the dose is hydrolysed within 3hr. Similar results are obtained if [35S]NCS is injected into anaesthetized rats in which kidney function has been eliminated by ligature of the renal pedicles. The labelled metabolite has been isolated from bile obtained by perfusing several rat livers with blood containing a total of 100mg. of [35S]NCS. It has been identified as 2-β-glucuronosido-5-nitrophenyl [35S]sulphate. The implications of the various findings are discussed. The Appendix describes the preparation of [35S]NCS.
Regulation of polyribosome formation and protein synthesis in the uterus. Isolation of cytoplasmic ribonucleoprotein particles and the principal properties of the cell-free protein-synthesizing system
Authors: Teng Ching-Sung , Hamilton Terrell H.
Published: August 2015

1. Three procedures for isolating ribonucleoprotein particles from the cytoplasmic fraction of rat-uterus homogenates are described. By procedure 1, ribonucleoprotein particles were isolated in the presence of 5mm-Mg2+ and 25mm-K+, and the postmitochondrial supernatant fraction was made to 1·3% (w/v) in potassium deoxycholate. About 50% of the RNA and protein of the microsomal fraction was recovered in the monomeric ribosomes isolated. By procedure 2, ribonucleoprotein particles were isolated in the presence of 10mm-Mg2+ and 0·1m-K+, and in the absence of detergent. The ribosomes obtained were primarily polymeric, but recovery of microsomal RNA and protein was only 32%. By procedure 3, ribonucleoprotein particles were isolated according to procedure 1 but without the use of detergent. A mixture of polymeric and monomeric ribosomes was obtained, and the recovery of microsomal RNA and protein was about 60%. 2. Uterine polymeric and monomeric ribosomes, isolated by procedure 3 and designated ‘polyribosomal preparation’, were examined for protein-synthesizing capabilities. The principal properties of the cell-free protein-synthesizing system containing the polyribosomal preparation are described. The efficiency of amino acid incorporation in the complete system incubated for 30min. and containing the polyribosomal preparation was found to be either 2·5 molecules of [14C]leucine or 2·2 molecules of [14C]-valine incorporated/ribosome. Assay of the preparation in the complete cell-free system containing 10mm-sodium fluoride indicated that 40% of the incorporation activity is a result of initiation of new polypeptide chains and 60% is due to completion of previously existing chains. Monomeric ribosomes obtained by various treatments of the polyribosomal preparation with sodium fluoride, ribonuclease and potassium deoxycholate had decreased incorporation activity in the cell-free system. However, monomeric ribosomes obtained by treatment with sodium fluoride only had an incorporation activity 50% greater than that of monomers obtained by treatment with ribonuclease only. 3. The results indicate that uterine polymeric and monomeric ribosomes are sites of amino acid incorporation in vivo and in vitro. It is concluded that most polymeric and monomeric ribosomes occurring in the cytoplasmic fraction of the uterus are free and unattached to membranes, and that the polyribosomes are relatively unstable.
Stimulation of rat testis microsomal 17α-hydroxyprogesterone side-chain cleavage enzyme by luteinizing hormone added in vitro
Authors: Hagerman Dwain D.
Published: August 2015

The addition of purified luteinizing hormone to isolated rat testis microsomes causes an increase in the activity of the enzyme system that converts 17α-hydroxyprogesterone into C19 steroids in these tissue organelles. The gonadotrophin does not act in this system by altering the Michaelis constants of the enzyme for either steroid or nicotinamide nucleotide, but rather appears specifically to increase the catalytic capability of the protein.
The macromolecular properties of blood-group substances. Sedimentation-velocity and viscosity measurements
Authors: Creeth J. M. , Knight C. G.
Published: August 2015

1. Sedimentation-velocity, intrinsic-viscosity and partial-specific-volume measurements on a typical blood-group-specific glycoprotein are reported for a range of environmental conditions. 2. The sedimentation coefficients, S, are strongly concentration-dependent, and follow the reciprocal law; the limiting values at 2°, 25° and 45°, after correction to 25°, show slight dependence on temperature. 3. The intrinsic viscosities, [η], at 25° and 45° show more marked temperature-dependence, and correspond to a very asymmetric or very expanded molecular conformation. 4. From the value of the ratio K/[η], where K=S0.d(1/S)/dc, it is concluded that the molecular conformation is roughly spherical; application of the Einstein viscosity equation then suggests an expansion factor of about 60, compatible with a flexible configuration approaching that of a random coil. 5. The sedimentation coefficient is not affected by variation of ionic strength in the range 0·01–0·50, nor by pH in the range 3–10. 6. Sodium dodecyl sulphate at 1·5% produces a small decrease in S; the effect is greater than would be expected from the observed extent of binding, but is too small to correspond to a significant change in secondary structure; the serological activity is unaffected by sodium dodecyl sulphate. 7. All the properties observed indicate the absence of any secondary structure in blood-group substances.
Organic pyrophosphates as substrates for human alkaline phosphatases
Authors: Eaton R. Helen , Moss D W
Published: August 2015

1. Purified human liver and small-intestinal alkaline orthophosphatases release inorganic phosphate at appreciable rates from a variety of organic pyrophosphate substrates. 2. The pyrophosphatase action is inhibited by Mg2+ ions at concentrations that activate the hydrolysis of orthophosphate substrates by these enzymes. 3. The results of mixed-substrate experiments, denaturation studies with heat or urea and starch-gel electrophoresis suggest that both orthophosphatase and pyrophosphatase activities are, in each preparation, properties of a single enzyme. 4. Intestinal phosphatase shows greater pyrophosphatase activity relative to orthophosphatase than the liver enzyme.
Potassium ions and the secretion of insulin by islets of Langerhans incubated in vitro
Authors: Howell S. L. , Taylor K W
Published: August 2015

1. A method was devised for the isolation of islets of Langerhans from rabbit pancreas by collagenase digestion in order to study the influx and efflux of K+ in islets during insulin secretion. 2. Glucose-induced insulin release was accompanied by an increased rate of uptake of 42K+ by the islets of Langerhans, though this was not the case for secretion in response to tolbutamide. Ouabain significantly inhibited the uptake of 42K+ by islet tissue. 3. No significant increase in the rate of efflux of 42K+ was demonstrated during active insulin secretion. 4. Slices of rabbit pancreas were incubated in media of different K+ content, and rates of insulin release were determined. Alteration of the K+ concentration of the medium between 3 and 8mm had no effect on the rate of insulin release by pancreas slices. However, decrease of the K+ concentration to 1mm resulted in inhibition of secretion in response to both glucose and to tolbutamide. Conversely, an increase in K+ concentration increased rates of insulin release in response to both these stimuli. 5. It is concluded that, though unphysiological concentrations of K+ may influence the secretion of insulin, fluxes of K+ in the islets do not appear to be important in the initiation of insulin secretion.
Inhibition of staphylococcal α-toxin. A kinetic evaluation of aromatic polysulphonic acids as inhibitors of haemolysis
Authors: Wright Margaret Robson , Arbuthnott J. P. , Lominski I. R. W.
Published: August 2015

1. The effect of a number of aromatic polysulphonic acids on the kinetics of haemolysis of rabbit erythrocyte suspensions by crude staphylococcal α-toxin was studied at pH8·6 and 6·8. 2. All of the inhibitory compounds caused an increase in the prelytic lag time (τ) of the sigmoid haemolysis curves, an increase in the time to reach 50% haemolysis (t½) and a decrease in the maximum rate of haemolysis (Rmax.). The most inhibitory compounds caused a 50% decrease in Rmax. at concentrations between 0·1 and 0·2mm. 3. The effect of pH varied considerably: compounds (I) and (II) were almost equally inhibitory at both pH values, compounds (IV) and (IX) were more inhibitory at pH6·8 than at pH8·6, and compounds (VII), (VIII), (X), (XI) and (XII) were more inhibitory at pH8·6. 4. Increased time of premixing α-toxin with compound (I) caused increased inhibition. 5. An attempt was made, where possible, to relate the inhibitory activity to the structure of the test compound.
The acid mucopolysaccharides of cattle retina
Authors: Berman E. R. , Bach G.
Published: August 2015

1. Two polysaccharides were isolated from the interstitial matrix surrounding the photoreceptor cells of cattle retina. They were liberated from this region of the tissue in a soluble form after agitation of whole retinas in 0·9% sodium chloride. One, which comprises two-thirds of the polysaccharides present, is a hyaluronidase-sensitive ‘half-sulphated’ chondroitin sulphate containing uronic acid, galactosamine and sulphate in the molar proportions 1·27:1·0:0·54. The other is a hyaluronidase-resistant non-sulphated heteropolysaccharide for which the name sialoglycan is proposed. It contains galactose, glucosamine and sialic acid in the molar proportions 2·4:1·0:0·4. Both polysaccharides contain only small amounts of nitrogen in excess of the amount calculated from their amino sugar and sialic acid content. 2. A similar combination of mucopolysaccharides is associated with the pigment epithelial-cell layer but in quantities only one-fifth of those present in the adjacent matrix area. 3. The ease with which they are released into aqueous media is consistent with the assumption that they are present in the extracellular spaces in both of these tissue layers. 4. The retinal residue left after removal of the two soluble polysaccharides is rich in amino sugar- and sialic acid-containing polymers, which appear to be firmly bound to the tissue fragments. 5. About one-third of the sialic acid and one-tenth of the amino sugar could be extracted with chloroform–methanol. The components in this fraction were tentatively identified as gangliosides. 6. Digestion of the chloroform–methanol-insoluble residue with Pronase yielded as the principal product a heteropolysaccharide containing 16·5% of glucosamine, 24·3% of neutral sugar (galactose plus fucose) and 18·1% of sialic acid. This substance has been classified as a sialoglycan of composition similar to (but not identical with) that of the soluble one isolated from the matrix area of the tissue.
Activity of nicotinamide–adenine dinucleotide pyrophosphorylase in liver nuclei. Effects of partial hepatectomy, hepatotoxins and dietary changes
Authors: Stirpe F. , Corte E. Della
Published: August 2015

1. The activity of NAD pyrophosphorylase is lower in nuclei isolated from regenerating rat liver than in normal nuclei, and this is due to leakage of the enzyme from the nuclei during the isolation. 2. The NAD pyrophosphorylase activity is lower in liver nuclei from newborn rats, and from rats on a protein-free diet, but no leakage occurs in these cases. 3. Poisoning with α-amanitin brings about a transient enhancement of NAD pyrophosphorylase activity in mouse liver nuclei. 4. No changes of enzyme activity were observed after 72hr. starvation, administration of actinomycin D or infection with MHV3 virus.
The phosphorylation of 5′-oligoadenylic acids by adenylate kinase and adenosine triphosphate
Authors: Klemperer H. G. , Harvey A. E. D.
Published: August 2015

1. Radioactivity was incorporated into 5′-O-phosphoryladenylyl-(3′-5′)-adenosine (pApA) on incubation with adenylate kinase and [γ−32P]ATP. The corresponding triadenylate and tetra-adenylate reacted more slowly. 2. Only oligoadenylate with a terminal 5′-phosphate served as the substrate. 3. The product formed from pApA was shown to behave like 5′-O-pyrophosphoryladenylyl-(3′-5′)-adenosine (ppApA) on hydrolysis with alkaline phosphatase, potassium hydroxide and hydrochloric acid. 4. The characteristics of the reaction indicated that it was catalysed by adenylate kinase, but the rate of phosphate transfer from ATP to pApA was about 0·01% of that in the typical reaction with AMP. 5. The reverse reaction between ADP and ppApA occurred readily, but no additional phosphorylation of ppApA (to give pppApA) could be demonstrated.
The partial characterization of 1-oxygenated steroids from urine of a hypertensive newborn child
Authors: Edwards R. W. H. , Trafford D. J. H.
Published: August 2015

1. Four substances from the urine of a hypertensive newborn girl were partially characterized and shown to be 17α-hydroxy-5β-pregnane-1,3,20-trione, 3α,17α-dihydroxy-5β-pregnane-1,20-dione, 3α,17α,20α-trihydroxy-5β-pregnan-1-one and 5β-pregnane-1β,3α,17α,20α-tetrol. 2. The characterization rested mainly on RM analysis of the substances and their derivatives by glycol fission, providing evidence for position and degree of substitution and for steroidal character. Supporting evidence was provided by chemically specific location reactions. 3. Certain problems in the manipulation of these β-disubstituted steroids are discussed.
A net gain of sodium ions and a net loss of potassium ions accompanying the uptake of glycine by mouse ascites-tumour cells in the presence of sodium cyanide
Authors: Eddy A A
Published: August 2015

1. The tumour cells were starved in a solution lacking Na+ and then transferred to a Ringer solution containing 2mm-sodium cyanide, 150m-equiv. of Na+/l. and 10m-equiv. of K+/l. Such cells were depleted of ATP and contained an endogenous pool of various amino acids equivalent to a 26mm solution. 2. At 4min. after the transfer the cellular Na+ content had increased by about 100% and roughly an equivalent amount of K+ had left the cells. 3. Under these conditions [14C]glycine was absorbed from an 11mm solution and reached the same cellular concentration by about 4min. The pool size increased by approximately the same amount (ΔGly), so glycine did not simply exchange with the endogenous components. 4. After 4min. with glycine, the cells contained about 20% more Na+ (ΔNa+) than the control and about 10% less K+ (ΔK+). The mean values of ΔNa+/ΔGly and ΔK+/ΔGly from five experiments were respectively 0·90±0·11 and 0·62±0·11equiv./mole. 5. A further indication that these two ratios were not equal was that the cells absorbed more water than the movement of glycine itself required. The excess of water was osmotically equivalent to 0·95±0·16equiv. of solute/mole of glycine absorbed. 6. The variation of ΔNa+/ΔGly with the duration of the incubation was consistent with the stimulated uptake of Na+ being linked to the actual transport of glycine. The same may apply to the movement of K+, though the time-dependence was not examined in that case. 7. The observations were analysed in terms of a model in which both K+ and Na+ moved with a glycine-carrier system without ATP being involved. The analysis supported the idea that the spontaneous movements of the ions through the system might concentrate glycine in the cells significantly by purely physical means (Christensen's hypothesis).
Incorporation of [5−3H]uridine and attachment of cells to glass during activation of lymphocytes induced by phytohaemagglutinin
Authors: Forsdyke D. R.
Published: August 2015

1. Shortly after the addition of phytohaemagglutinin to cultures, partially purified pig blood lymphocytes showed increased labelling of RNA by [5−3H]uridine and began to attach to the glass of the culture tubes. 2. In the presence of phytohaemagglutinin most cells became attached to glass during the first 5hr. of culture; those first attaching had a low mean RNA/DNA ratio. In the absence of phytohaemagglutinin cell attachment to glass was diminished. 3. During the first 5hr. of culture the rates of increase of radioactivity/unit of DNA of the attached and unattached populations in the presence of phytohaemagglutinin were of the same order and exceeded that of cultures without phytohaemagglutinin. 4. The increase of labelling in cultures to which phytohaemagglutinin was added after cells had sedimented to glass was greater than that occurring in cultures in which cells were resuspended before phytohaemagglutinin was added.
Structure of the cell wall of lactobacilli. Role of muramic acid phosphate in Lactobacillus fermenti
Authors: Knox K. W. , Holmwood Klara J.
Published: August 2015

1. The polysaccharide and mucopeptide components of the cell wall of Lactobacillus fermenti, serological group F, were separated by mild conditions of acid hydrolysis; the polysaccharide was composed of glucose and galactose. 2. Soluble cell-wall products were isolated from cell wall lysed by lysozyme and a Streptomyces enzyme preparation. The lysozyme-dissolved fraction contained a greater proportion of mucopeptide. 3. The soluble preparations were heated in dilute acid to hydrolyse the linkage between the polysaccharide and mucopeptide components and then incubated with acid phosphatase. 4. Inorganic phosphate was released from products of Streptomyces enzyme action but not from products of lysozyme action. 5. The phosphate was shown to be present in the mucopeptide as muramic acid phosphate. It is concluded that in the intact wall polysaccharide is joined to muramic acid by a phosphodiester linkage.
The reaction of 2,4,6-trinitrobenzenesulphonic acid with amino acids, peptides and proteins
Authors: Freedman R. B. , Radda G. K.
Published: August 2015

1. The kinetics of the reaction of 2,4,6-trinitrobenzenesulphonic acid with various amino acids, peptides and proteins were studied by spectrophotometry. 2. The reaction of the α- and ∈-amino groups in simple amino acids was found to be second-order, and the unprotonated amino group was shown to be the reactive species. 3. By allowing for the concentration of unreactive −NH3+ group, intrinsic reactivities for the free amino groups were derived and shown to be correlated with the basicities. 4. The SH group of N-acetylcysteine was found to be more reactive to 2,4,6-trinitrobenzenesulphonic acid than most amino groups. 5. The reactions of insulin, chymotrypsinogen and ribonuclease with 2,4,6-trinitrobenzenesulphonic acid were analysed in terms of three exponential rate curves, each referring to one or more amino groups of the proteins. 6. The reaction of lysozyme with 2,4,6-trinitrobenzenesulphonic acid was found to display an acceleration effect. 7. From the reaction of 2,4,6-trinitrobenzenesulphonic acid with glutamate dehydrogenase at several enzyme concentrations, it was possible to discern two sets of amino groups of different reactivity, and to show that the number of groups in each set was decreased by aggregation of the enzyme.
The effects of catabolic and anabolic steroids on amino acid incorporation by skeletal-muscle ribosomes
Authors: Bullock Gillian , White A M , Worthington Judy
Published: August 2015

1. A method is described for the routine isolation of ribosomes from small quantities of skeletal muscle that have been homogenized with the Ultra-Turrax tissue disintegrator. 2. Ribosomes prepared by this method from rats receiving triamcinolone acetonide or rabbits receiving cortisone acetate show a marked fall in their ability to incorporate amino acids when compared with ribosomes from control animals. 3. This fall in activity can be partially prevented in rats by pretreating the animals with an anabolic steroid, steroid 36644-Ba. 4. Testosterone (5mg./kg.) administered to rabbits in conjunction with cortisone acetate is not effective in maintaining ribosomal activity. However, steroid 36644-Ba at one-tenth of an equiandrogenic dose (0·05mg./kg.) is extremely effective. 5. The results with ribosomes isolated from rabbits support the concept that steroid 36644-Ba and possibly all anabolic steroids have an ability to counteract the catabolic action of corticosteroids that is greater than their androgenic activity would suggest.
The pattern and control of isoprenoid quinone and tocopherol metabolism in the germinating grain of wheat (Triticum vulgare)
Authors: Hall G. S. , Laidman D L
Published: August 2015

1. The syntheses of ubiquinone-9 and plastoquinone-9 were used as parameters respectively of mitochondrial and proplastid development in the germinating wheat grain. 2. The changes in the amounts of the tocopherols were also studied and the possible biological significance of these changes is discussed. During germination, the dimethyl tocopherols of the resting grain are probably not utilized for the synthesis of α-tocopherol. 3. It was demonstrated that ubiquinone synthesis, and hence probably mitochondrial development, in the aleurone cells during germination, is independent of control by gibberellic acid from the embryo. 4. The influence of light on the syntheses of the isoprenoid quinones in the etiolated wheat shoot was investigated. In particular, illumination did not stimulate the synthesis of either α-tocopherol or α-tocopherolquinone.
The role of deoxycorticosterone in the biosynthesis of cardenolides in Digitalis lanata
Authors: Caspi E , Wickramasinghe J. A. F. , Lewis D. O.
Published: August 2015

The role of deoxycorticosterone in the biosynthesis of digitoxigenin was investigated by the simultaneous administration of deoxy[1,2−3H2]corticosterone and [4−14C]progesterone to a Digitalis lanata plant. The biosynthetically formed [3H,14C]digitoxigenin and deoxy[3H,14C]corticosterone were isolated and the distribution of the two isotopes in these products was determined. The transformation of progesterone into deoxycorticosterone in vivo was established. The biosynthetic route from progesterone via deoxycorticosterone to cardenolides was found to be of little significance.
Biosynthesis of putrescine in the prostate gland of the rat
Authors: Pegg A E , Williams-Ashman H G
Published: August 2015

In the rat ventral prostate gland the biosynthesis of putrescine, a precursor of spermidine and spermine, is shown to occur by the direct decarboxylation of l-ornithine. Some properties of a soluble pyridoxal phosphate-dependent l-ornithine decarboxylase are described. The findings are discussed in relation to other enzymic reactions involved in the biosynthesis of polyamines by the prostate gland.
The metabolism of tetralin
Authors: Elliott T H , Hanam J.
Published: August 2015

1. [1−14C]Tetralin was synthesized and fed to rabbits. 2. Of the radioactivity, 87–90% was excreted in the urine within two days and 0·5–3·7% on the third day. The faeces contained 0·6–1·8%. No radioactivity was found in the breath and negligible amounts were retained in the tissues. About 90–99% of an administered dose was accounted for. 3. The main metabolite in the urine was the glucuronide of α-tetralol (52·4%). Other conjugated metabolites were β-tetralol (25·3%), 4-hydroxy-α-tetralone (6·1%), cis-tetralin-1,2-diol (0·4%) and trans-tetralin-1,2-diol (0·6%). 4. β-Tetralone, α-naphthol, 1,2-dihydronaphthalene and naphthalene, previously reported as metabolites, are artifacts, and tetralin, α-tetralone, β-naphthol, 5-hydroxytetralin, and 6-hydroxytetralin are not metabolites. 5. The major metabolite of tetralin, α-tetralol and α-tetralone is the glucuronide of α-tetralol, which was isolated as methyl (1,2,3,4-tetrahydro-1-naphthyl tri-O-acetyl-β-d-glucosid)uronate; the major metabolite of β-tetralol and β-tetralone is the glucuronide of β-tetralol, which was characterized as methyl (1,2,3,4-tetrahydro-2-naphthyl tri-O-acetyl-β-d-glucosid)uronate. 5-Hydroxytetralin is conjugated with glucuronic acid, and was characterized as methyl (5,6,7,8-tetrahydro-1-naphthyl tri-O-acetyl-β-d-glucosid)uronate. 6-Hydroxytetralin is conjugated with glucuronic acid, and was characterized as methyl (5,6,7,8-tetrahydro-2-naphthyl tri-O-acetyl-β-d-glucosid)uronate. 6. A metabolic sequence accounting for the observed biological transformation products is proposed.
Carbohydrate content of bovine collagen preparations
Authors: Grant M. E. , Jackson D. S.
Published: August 2015

Collagen preparations from bovine tissues were analysed for their carbohydrate content. Crude preparations of tropocollagen and polymeric collagen were found to be contaminated with considerable amounts of mannose, fucose and hexosamine, sugars known to be present in the mucoprotein of the interfibrillar material with which collagen is associated in vivo. A pure preparation of tropocollagen obtained by ethanol precipitation procedures contained only galactose and glucose in the approximate ratio of 7:3 residues/3000 amino acid residues. Purification of crude polymeric collagen by EDTA extraction or by crude bacterial amylase extraction considerably decreased the mucoprotein contamination, particularly in the enzymic treatment, which yielded a preparation containing predominantly galactose and glucose in the ratio of 4:2 residues/3000 amino acid residues. The results confirm previous work that demonstrated the purity of these collagen preparations as inferred by amino acid analysis. The results also indicate the suitability of the pure tropocollagen and the amylase-extracted polymeric collagen for studies on the role of the carbohydrate residues in intramolecular and intermolecular cross-linking in collagen.
The mechanism of disulphide reduction by mitochondria
Authors: Skrede S.
Published: August 2015

1. Cystamine was reduced to the corresponding thiol by rat liver mitochondria, even in the presence of rotenone or antimycin A. 2. The reduction of disulphides was stimulated by the accumulation of NADH or by the addition of NADH to osmotically ‘shocked’ mitochondria. 3. Energy made available by oxidative phosphorylation was not essential for the reduction of disulphides. 4. Cystamine was not reduced during the oxidation of NADH by ultrasonically treated particles, which had lost their capacity for oxidation of α-oxo acids. 5. In intact mitochondria, arsenite and other inhibitors of vicinal dithiols caused a decrease in the capacity for reduction of disulphides concomitantly with an inhibition of the oxidation of α-oxo acids. 6. Isolated lipoamide dehydrogenase reduced cystamine at the expense of NADH, provided that lipoic acid was also present. 7. It is concluded that in mitochondria the reduction of cystamine and related disulphides is probably brought about by interaction with reduced lipoic acid, generated by the α-oxo acid dehydrogenase complexes during the oxidation of α-oxo acids or by reaction of lipoamide dehydrogenase with NADH.
The effect of actinomycin D on the synthesis of ribonucleic acid and protein in rat liver parenchymal cells in suspension and liver slices
Authors: Shanmugam G. , Bhargava P. M.
Published: August 2015

1. Rat liver parenchymal cells in suspension are shown to require a higher concentration of actinomycin D than liver slices for equivalent inhibition of the incorporation of [14C]adenine, [14C]uracil and [32P]phosphate into RNA, and of 14C-labelled amino acids into protein; protein synthesis is much less susceptible to actinomycin D inhibition than RNA synthesis in both the tissue preparations. Possible causes for these differences are discussed. 2. The uptake of [3H]actinomycin D in the first few minutes was much greater in the cell suspensions than in the tissue slices; that in the next 1–4hr. was about the same in both the cases. The uptake by both the tissue preparations was at all times proportional to the concentration of the drug within the range 0·5–2·0μg./ml. 3. In the slices actinomycin D taken up initially was concentrated almost exclusively in the nuclei; with time the concentration of the drug in the mitochondria and the supernatant increased more rapidly than in the nuclei though at no stage did it exceed that in the nuclei. In the cell suspension the largest concentration of the drug taken up initially was found in the supernatant; most of the drug taken up subsequently also stayed in the supernatant. 4. When the drug concentration in the incubation medium was 1μg./ml., its concentration within the parenchymal cells in suspension and the parenchymal cells in the slices reached 2·2 and 1·6μg./cm.3 of cellular volume respectively. On average, 7% of the drug was removed from the medium by the cells in suspension and 23% by the cells in the slices; the average ratio of intracellular to extracellular concentration was 2·4 in the former and 2·1 in the latter case.