bluuebunny/crossref_metadata_2025 huggingface dataset:
IGF-1 Regulates Vertebral Bone Aging Through Sex-Specific and Time-Dependent Mechanisms
Authors: Ashpole Nicole M , Herron Jacquelyn C , Mitschelen Matthew C , Farley Julie A , Logan Sreemathi , Yan Han , Ungvari Zoltan , Hodges Erik L , Csiszar Anna , Ikeno Yuji , Humphrey Mary Beth , Sonntag William E
Published: August 2015

Advanced aging is associated with increased risk of bone fracture, especially within the vertebrae, which exhibit significant reductions in trabecular bone structure. Aging is also associated with a reduction in circulating levels of insulin-like growth factor (IGF-1). Studies have suggested that the reduction in IGF-1 compromises healthspan, whereas others report that loss of IGF-1 is beneficial because it increases healthspan and lifespan. To date, the effect of decreases in circulating IGF-1 on vertebral bone aging has not been thoroughly investigated. Here, we delineate the consequences of a loss of circulating IGF-1 on vertebral bone aging in male and female Igff/f mice. IGF-1 was reduced at multiple specific time points during the mouse lifespan: early in postnatal development (crossing albumin–cyclic recombinase [Cre] mice with Igff/f mice); and in early adulthood and in late adulthood using hepatic-specific viral vectors (AAV8-TBG-Cre). Vertebrae bone structure was analyzed at 27 months of age using micro–computed tomography (μCT) and quantitative bone histomorphometry. Consistent with previous studies, both male and female mice exhibited age-related reductions in vertebral bone structure. In male mice, reduction of circulating IGF-1 induced at any age did not diminish vertebral bone loss. Interestingly, early-life loss of IGF-1 in females resulted in a 67% increase in vertebral bone volume fraction, as well as increased connectivity density and increased trabecular number. The maintenance of bone structure in the early-life IGF-1–deficient females was associated with increased osteoblast surface and an increased ratio of osteoprotegerin/receptor-activator of NF-κB-ligand (RANKL) levels in circulation. Within 3 months of a loss of IGF-1, there was a 2.2-fold increase in insulin receptor expression within the vertebral bones of our female mice, suggesting that local signaling may compensate for the loss of circulating IGF-1. Together, these data suggest the age-related loss of vertebral bone density in females can be reduced by modifying circulating IGF-1 levels early in life. © 2015 American Society for Bone and Mineral Research.
Doping behavior of GaN grown on patterned sapphire substrates
Authors: Meisch Tobias , Zeller Raphael , Schörner Sabine , Thonke Klaus , Kirste Lutz , Fuchs Theo , Scholz Ferdinand
Published: August 2015

Abstractauthoren We present results of the investigation on the doping behavior of planar semipolar ‐oriented GaN grown on patterned sapphire substrates mainly focusing on the magnesium incorporation. We observed that Mg is incorporated with much lower efficiency into the plane as compared to polar c‐plane GaN. This problem could be decreased by varying the growth temperature. We found higher Mg concentrations with constant Mg flow for reduced growth temperature. Simultaneously, the parasitic background carrier concentration was reduced. Using this optimization, a planar semipolar InGaN/GaN‐LED on ‐oriented GaN was grown. Electroluminescence measurements show reasonable electrical and optical performance.
Usefulness of WISC-IV in Determining Intellectual Giftedness
Authors: Molinero Clara , Mata Sara , Calero Mª Dolores , García-Martín Mª Belén , Araque-Cuenca Arsenio
Published: August 2015

Several studies question the usefulness of the Wechsler Intelligence Scale for Children (WISC-IV) in determining giftedness due to the importance of speed in some of its subtests, which may penalize children of high intellectual level. This study analyzes the factor structure of the WISC-IV of gifted children based on confirmatory factor analysis. Participants were eighty-seven gifted children from Spain (6–13 years old). Score discrepancies were also examined for the main indexes: Verbal Comprehension, Processing Speed, Working Memory and Perceptual Organization. Results pointed out four models with a good fit from the five models analyzed: a two-factor model according to GAI subscales (RMSEA = .001,p= .84), a four-factor first-order model including main indexes (RMSEA = .05,p= .19), a four-factor model withgas a direct factor (RMSEA = .001,p= .84) and a four-factor model withgas an indirect higher-order factor (RMSEA = .05,p= .13). Discrepancies were found between Verbal Comprehension and Processing Speed, and between Perceptual Organization and Processing Speed. Verbal Comprehension yielded the highest score, whereas the lowest scores were obtained in Processing Speed and Working Memory. These results support the use of this scale in the assessment and diagnosis of Spanish children with a high intellectual level.
Piezotransistive transduction of femtoscale displacement for photoacoustic spectroscopy
Authors: Talukdar Abdul , Faheem Khan M. , Lee Dongkyu , Kim Seonghwan , Thundat Thomas , Koley Goutam
Published: August 2015

Measurement of femtoscale displacements in the ultrasonic frequency range is attractive for advanced material characterization and sensing, yet major challenges remain in their reliable transduction using non-optical modalities, which can dramatically reduce the size and complexity of the transducer assembly. Here we demonstrate femtoscale displacement transduction using an AlGaN/GaN heterojunction field effect transistor-integrated GaN microcantilever that utilizes piezoelectric polarization-induced changes in two-dimensional electron gas to transduce displacement with very high sensitivity. The piezotransistor demonstrated an ultra-high gauge factor of 8,700 while consuming an extremely low power of 1.36 nW, and transduced external excitation with a superior noise-limited resolution of 12.43 fm Hz−1/2 and an outstanding responsivity of 170 nV fm−1, which is comparable to the optical transduction limits. These extraordinary characteristics, which enabled unique detection of nanogram quantity of analytes using photoacoustic spectroscopy, can be readily exploited in realizing a multitude of novel sensing paradigms.
Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance vibrational spectroscopy
Authors: Ogata Hideaki , Krämer Tobias , Wang Hongxin , Schilter David , Pelmenschikov Vladimir , van Gastel Maurice , Neese Frank , Rauchfuss Thomas B. , Gee Leland B. , Scott Aubrey D. , Yoda Yoshitaka , Tanaka Yoshihito , Lubitz Wolfgang , Cramer Stephen P.
Published: August 2015

The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the 57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique ‘wagging’ mode involving H− motion perpendicular to the Ni(μ-H)57Fe plane was studied using 57Fe-specific nuclear resonance vibrational spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe–CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)57Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)57Fe(CO)3]+ and DFT calculations, which collectively indicate a low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H− binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe–H moieties in other important natural and synthetic catalysts.
A hydrogen bonded molecular capsule versus a 3D network of tripodal organopolysilanols
Authors: Fukawa Marina , Sato Takayuki , Kabe Yoshio
Published: August 2015

1,3,5-Triethylbenzene based tripodal trisilanols were synthesized. X-ray, NMR and ESI-mass spectra disclosed the first example of an organotrisilanol molecular capsule based on a 1,3,5-triethylbenzene scaffold which showed encapsulation of H2O or halogen anions in both the crystalline and solution states.
Born–Oppenheimer and Renner–Teller coupled-channel quantum reaction dynamics of O(3P) + H2+(X2Σg+) collisions
Authors: Gamallo Pablo , Defazio Paolo , González Miguel , Paniagua Miguel , Petrongolo Carlo
Published: August 2015

We present Born–Oppenheimer (BO) and Renner–Teller (RT) time dependent quantum dynamics studies of the reactions O(3P) + H2+(X2Σg+) → OH+(X3Σ−) + H(2S) and OH(X2Π) + H+.
Neurotoxicity effects of atrazine-induced SH-SY5Y human dopaminergic neuroblastoma cells via microglial activation
Authors: Ma Kun , Wu Hao-Yu , Zhang Bo , He Xi , Li Bai-Xiang
Published: August 2015

Atrazine (2-chloro-4-ethytlamino-6-isopropylamine-1,3,5-triazine; ATR) is a broad-spectrum herbicide with a wide range of applications worldwide.
Diastereoselective synthesis of pitavastatin calcium via bismuth-catalyzed two-component hemiacetal/oxa-Michael addition reaction
Authors: Xiong Fangjun , Wang Haifeng , Yan Lingjie , Xu Lingjun , Tao Yuan , Wu Yan , Chen Fener
Published: August 2015

An efficient and concise asymmetric synthesis of pitavastatin calcium (1) starting from commercially available (S)-epichlorohydrin is described.
Growth and synthesis of mono and few-layers transition metal dichalcogenides by vapour techniques: a review
Authors: Bosi Matteo
Published: August 2015

Nanosheet materials such as graphene, boron nitride and transition metal dichalcogenides have gathered attention in recent years thanks to their properties and promises for future technology, energy generation and post-CMOS device concepts.
Influence of adsorption parameters on cesium uptake from aqueous solutions- a brief review
Authors: Olatunji Michael Adekunle , Khandaker Mayeen Uddin , Mahmud H. N. M. Ekramul , Amin Yusoff Mohd
Published: August 2015

Due to rapid population growth, technological advancement and industrial revolution, the rate of generated waste effluents has become a grave concern.
Porous polystyrene spheres loaded self nano-emulsifying systems of rosuvastatin calcium
Authors: R Panner Selvam , P. K Kulkarni , V Naga Sravan Kumar Varma
Published: August 2015

The aim of the study was to investigate potential of Solid Self Nano-Emulsifying Drug Delivery System (SNEDDS) for enhancing solubility and oral bioavailability of Rosuvastatin Calcium (RC).
Experimental and computational analysis of transition metal ion-doped AlInN/GaN thin films
Authors: Majid Abdul
Published: August 2015

Experimental and computational analysis of transition metal ion-doped AlInN/GaN thin films.
The distinctively singular self-assembly of a “molecular stair”: observation of a quadrilateral C–H⋯O hydrogen bonding cycle in the crystal structure of a tetracyclic oligo-tetrahydrofuran
Authors: Rashid Showkat , Bhat Bilal A. , Sen Saikat , Mehta Goverdhan
Published: August 2015

A comparative analysis of the crystal structures of three structurally related molecular stairs has identified a rare C–H⋯O H-bonding motif and revealed the significant role played by the peripheral THF moieties in their modes of self-assembly.
A versatile gold cross-linked nanoparticle based on triblock copolymer as the carrier of doxorubicin
Authors: Jeon Sangmin , Ko Hyewon , Vijayakameswara Rao N. , Yoon Hong Yeol , You Dong Gil , Han Hwa Seung , Um Wooram , Saravanakumar Gurusamy , Park Jae Hyung
Published: August 2015

Gold cross-linked nanoparticles based on PCL-b-PDMAEMA-b-PEG triblock copolymer has been developed as a carrier for anticancer drugs with enhanced biostability.
Synthesis and characterization of a Pd/Ag bimetallic nanocatalyst on SBA-15 mesoporous silica as a plasmonic catalyst
Authors: Verma Priyanka , Kuwahara Yasutaka , Mori Kohsuke , Yamashita Hiromi
Published: August 2015

A uniformly dispersed Pd/Ag bimetallic system supported on mesoporous silica SBA-15 was synthesized by a two-step method.
Magnetic field modulated upconversion luminescence in NaYF4:Yb,Er nanoparticles
Authors: Chen P. , Jia H. , Zhong Z. , Han J. , Guo Q. , Zhou J. , Liu X. , Qiu J.
Published: August 2015

Magnetic field enhanced the upconversion luminescence for the enhanced energy transfer from Yb3+ to Er3+ in NaYF4 nanoparticles.
Enhancement of the thermoelectric properties of n-type PbTe by Na and Cl co-doping
Authors: Cohen I. , Kaller M. , Komisarchik G. , Fuks D. , Gelbstein Y.
Published: August 2015

In an attempt to reduce our reliance on fossil fuels, associated with severe environmental effects, the current research is focused on the enhancement of the direct thermal to electrical thermoelectric efficiency of n-type PbTe by Na and Cl co-doping.
The transformation and resolution of 8-aza steroids by fungi
Authors: Curtis PJ
Published: August 2015

1. When (+/-)-8-aza-d-homo-oestrone 3-methyl ether was added to a culture of Aspergillus ochraceus, the laevo-rotatory enantiomer is reduced to a 17A alcohol. Thus (+/-)-8-aza-d-homo-oestrone 3-methyl ether has been resolved into both its components, the laevo-rotatory enantiomer being obtained by chromic acid oxidation of the alcohol, and the dextro-rotatory enantiomer as residual precursor from the fermentation. 2. Fungi have been found to demethylate the 3-methyl ethers of 8-aza steroids to the corresponding phenols. In particular, 8-aza-d-homo-oestrone 3-methyl ether was demethylated by Aspergillus flavus and 8-aza-d-homo-oestradiol 3-methyl ether by Cunninghamella blakesleeana.
A study of the biosynthesis of collagenous and non-collagenous proteins and of the proline/hydroxyproline ratios of collagens isolated from embryonic tissues
Authors: Hurych J , Chvapil M
Published: August 2015

1. After incubation of chick-embryo skin slices with [(14)C]proline for 2hr. the specific activities of [(14)C]proline and [(14)C]hydroxyproline in soluble and insoluble collagens and [(14)C]proline in non-collagenous proteins were determined as well as the total amounts of both imino acids in these proteins. On the basis of these results it was demonstrated that soluble collagens having a high proline/hydroxyproline ratio are contaminated with non-collagenous proteins. 2. It was found that, in the presence of a mixture of amino acids in the incubation medium, the rate of synthesis of soluble collagen is significantly decreased. 3. The metabolic activity of collagenous proteins is related to their solubility, but that of non-collagenous proteins is not.
The influence of sialic acid residues on the ability of glycoproteins toi nteract electrostatically with chondromucoprotein
Authors: Anderson AJ
Published: August 2015

1. Although glycoproteins with less than 1% of sialic acid (fibrinogen, lipoproteins, gamma-globulins) interact electrostatically with chondromucoprotein to form insoluble complexes, interaction with glycoproteins containing larger amounts of sialic acid (orosomucoid, urine glycoprotein, seromucoid, fraction VI) was electrostatically impossible. Reasons for this are discussed. 2. The latter glycoproteins interacted with chondromucoprotein after mild acid hydrolysis or neuraminidase treatment, complex-formation being inversely related to their sialic acid content. 3. Complex-formation with sialic acid-deficient orosomucoid was maximum at pH3.6 and negligible above its isoelectric point of pH5, and was inhibited by Ca(2+) ions and EDTA. 4. These results are discussed in relation to the carbohydrate composition and biological activities of euglobulin fractions, and of complexes formed by adding chondromucoprotein to abnormal plasmas which may contain sialic acid-deficient glycoproteins owing to faulty carbohydrate metabolism.
A method for the estimation of thiol esters
Authors: Cecil R , Ferdinand W
Published: August 2015

1. A method is described for the estimation of thiol ester groups. The thiol ester is converted into the corresponding thiol by reaction with ammonia; the thiol is then titrated amperometrically with mercuric chloride. 2. The method may be used in the presence of SH and S.S groups. The SH groups are titrated at pH3 in the presence of excess of chloride; under these conditions thiol esters do not react with mercuric chloride. Thiol ester plus thiol is then estimated by titration after reaction with ammonia. Finally, titration after reaction with ammonia and sulphite gives the thiol ester plus thiol plus disulphide. 3. The procedure has been applied to glyceraldehyde phosphate dehydrogenase. The enzyme was found to contain 15-16 SH groups/mol. and no S.S groups. After reaction with acetyl phosphate 1.8-3.5 thiol ester groups were detected, the number depending on the conditions of acetylation. In the absence of bound NAD, the number of thiol ester groups formed was 1.8/mol., although a value of 2.9 labile acetyl groups/mol. was given by the method of Lipmann & Tuttle (1945). The presence of thiol ester groups in the S-(d-3-phosphoglyceryl)-enzyme was also demonstrated.
The effect of bile, bile acids and detergents on calcium absorption in the chick
Authors: Webling DDA , Holdsworth ES
Published: August 2015

1. Bile from rachitic or normal chicks causes an immediate increase in the intestinal absorption of soluble calcium in rachitic and vitamin D(3)-treated chicks as tested in vivo by intestinal-loop and oral-dosing methods. 2. This effect is apparently solely due to the taurine-conjugated bile acids present in the bile and is independent of the action of vitamin D. 3. Chick bile and bile acids can increase the solubility and the absorption of calcium presented as sparingly soluble calcium hydrogen phosphate. 4. In addition, bile is necessary to some extent at least for the intestinal absorption of vitamin D(3) in the chick and this would indirectly enhance the absorption of calcium. 5. Thus bile is capable of a threefold action in the absorption of calcium in the chick. It is suggested that the direct action on sparingly soluble forms of calcium is of considerable physiological importance since most of the calcium in the normal bird's diet would be in this form. 6. Bile acids enhance the absorption of calcium in all regions of the small intestine of the chick. 7. Of a range of bile acids and detergents tested for enhancement of calcium absorption, various taurine-conjugated bile acids and sodium lauryl sulphate, an anionic detergent, are effective. A non-ionic detergent (Tween 80) and a cationic detergent (Zephiran) are without effect. 8. The ability of a substance to increase directly the intestinal absorption of soluble calcium appears to depend to some extent on an anionic detergent action, i.e. the ability to form a salt or complex soluble to some extent in both aqueous and lipid phases. 9. In chicks the immediate deposition of calcium ((45)Ca) in the bones closely reflects any increase in plasma calcium radioactivity regardless of the cause of the increase and regardless of the vitamin D(3) status. Although sodium lauryl sulphate can increase markedly the calcium absorption from the gut and the immediate deposition in the bones it has no significant effect on rickets. 10. Some of the implications of these findings are discussed.
Observations on iron uptake, iron metabolism, cytochrome c content, cytochrome a content and cytochrome c-oxidase activity in regenerating rat liver
Authors: Gear ARL
Published: August 2015

1. Differential and density-gradient centrifugation were used to fractionate mitochondria and fluffy layer from normal and regenerating rat liver. The iron, cytochrome a and cytochrome c contents and cytochrome c-oxidase activity were studied as well as the uptake of (59)Fe into protein and cytochrome c. 2. A certain degree of heterogeneity was evident between the heavy-mitochondrial and light-mitochondrial fractions, and in their behaviour during liver regeneration. 3. The specific content of light-mitochondrial iron and cytochrome a was 1.3-1.4 times that of heavy mitochondria. Changes in cytochrome c-oxidase activity closely followed those of cytochrome a content during liver regeneration, but not for light mitochondria after 10 days. 4. Radioactive iron ((59)Fe) was most actively taken up by well-washed light mitochondria during early liver regeneration. After 22 days fluffy layer became preferentially labelled. This substantiates the view that fluffy layer partially represents broken-down mitochondria. 5. During early regeneration, light-mitochondrial fractions separated along a density gradient were about 3 times as radioactive, and showed distinct heterogeneity of (59)Fe-labelling, in contrast with near homogeneity for heavy mitochondria. 6. Immediately after partial hepatectomy fractions corresponding to density 1.155 were 5-10 times as radioactive as particles of greater density. The radioactivity decreased sharply after 6 days. 7. These particles of low density possessed higher NADH-cytochrome c-reductase (1.5-5-fold) and succinate-dehydrogenase (1.1-2-fold) activities than typical mitochondrial fractions. Their succinate-cytochrome c-reductase and cytochrome c-oxidase activities were slightly lower. 8. The results are discussed in relation to mitochondrial morphogenesis, and a possible route from submitochondrial particles is suggested.
A chromatographic preparation of ox growth hormone
Authors: Wallis M , Dixon HBF
Published: August 2015

1. A method is described for the chromatographic preparation of ox growth hormone. It involves chromatography of an extract of anterior pituitary lobes on DEAE-cellulose, followed by rechromatography on a dextran gel of low cross-linkage (Sephadex G-100). 2. The product is highly active in growth-hormone assays, and is obtained in good yield. It was homogeneous by several criteria, but showed some heterogeneity on starch-gel electrophoresis. 3. The molecular weight of the hormone was estimated from its behaviour on gel-filtration columns under various conditions. Evidence that the hormone may dissociate into sub-units under some conditions is presented.
A rapid assay for peroxidase activity
Authors: Gregory RPF
Published: August 2015

1. Peroxidase has been assayed by a chronometric method involving the coupled reaction of ascorbic acid with the product of the enzymic action on benzidine. 2. Measurements of the activities of horseradish and tea peroxidase by this and two other methods, involving respectively pyrogallol and o-dianisidine, are compared. 3. It is claimed that the chronometric method is relatively simple, rapid and accurate. 4. The method can be used in the presence of polyphenol oxidases.
An early intermediate in the biosynthesis of biotin: Incorporation studies with [1,7-14C2]pimelic acid
Authors: Eisenberg M A , Maseda R
Published: August 2015

1. An unknown biotin vitamer was obtained in high yields in culture filtrates of Penicillium chrysogenum. 2. Production of this vitamer and desthiobiotin is controlled by the biotin concentration in the medium. 3. The unknown vitamer becomes labelled when the organism is grown in the presence of radioactive pimelic acid. 4. Chromatographic procedures were developed for the purification of the radioactive vitamer. 5. The vitamer is extremely stable in concentrated acid but gives rise to new vitamers under certain conditions. 6. The intermediate role of this vitamer in the synthesis of biotin is discussed.
Biosynthesis of phytoquinones. Incorporation of l-[Me−14C3H]methionine into terpenoid quinones and chromanols in maize shoots
Authors: Threlfall D R , Whistance G R , Goodwin T W
Published: August 2015

1. Radioactivity from l-[Me−14C,3H]methionine is incorporated into phylloquinone, plastoquinone, γ-tocopherol, α-tocopherol, α-tocopherolquinone and ubiquinone in maize shoots. 2. Comparative studies with other terpenoids (squalene and β-carotene) and chemical degradation of selected quinones (ubiquinone and plastoquinone) established that all the radioactivity is confined to nuclear methyl substituents. 3. In ubiquinone 76% of the radioactivity is in the methoxyl groups and 24% in the ring C-methyl group. 4. Taking the phytosterols as an internal reference and accepting the atomic ratio of 14C/3H transferred from l-[Me−14C,3H]methionine to the supernumerary group at C24 to be 1:2 the ratio of all the quinones and chromanols examined approached 1:3. After allowing for the fact that for plastoquinone, γ-tocopherol, α-tocopherol and α-tocopherolquinone one nuclear methyl group is formed from the β-carbon of tyrosine, these results show that one nuclear C-methyl group for phylloquinone, plastoquinone and γ-tocopherol, two nuclear methyl groups for α-tocopherol and α-tocopherolquinone and one nuclear methyl and two methoxyl groups for ubiquinone are formed by the transfer of intact methyl groups from methionine. 5. From a comparison of the incorporation of 14C radioactivity into these compounds it would appear that the methylation reactions involved in phylloquinone and plastoquinone biosynthesis take place in the chloroplast, whereas those involved with ubiquinone biosynthesis occur else-where within the cell.
Hydrocortisone requirement for the induction of glutamine synthetase in chick-embryo retinas
Authors: Reif-Lehrer Liane , Amos Harold
Published: August 2015

Hydrocortisone has been found to induce glutamine synthetase activity in chick-embryo retinas in culture. Evidence is presented to show that the hydrocortisone is definitely required for transcription; its requirement for translation has not been ruled out. The possible identity of hydrocortisone with an active component of calf-serum diffusate reported earlier is discussed. The data also indicate that the glutamine synthetase messenger RNA is stable for at least several hours.
Precursor–product relationship between intrahepatic albumin and plasma albumin
Authors: LeBouton A. V.
Published: August 2015

Rats were injected with [3H]leucine, and at various times thereafter labelled albumin was isolated by electrophoresis from their livers and blood plasma. The specific radioactivity of each protein was determined by spectrophotometry and liquid-scintillation spectrometry. Intrahepatic albumin was shown to be identical with plasma albumin by its electrophoretic mobility and antigenicity. It was found that intrahepatic albumin was the direct precursor of plasma albumin. Comparison of their specific radioactivities showed that intrahepatic albumin attained a higher specific radioactivity before plasma albumin. When plasma albumin reached its maximum specific radioactivity, that of intrahepatic albumin had decreased to a similar value. Thereafter, the specific radioactivity of intrahepatic albumin remained lower than that of plasma albumin.
Hepatic glutathione concentrations linked to ethionine toxicity in rats
Authors: Hsu J. M. , Buchanan P. J. , Anilane J. , Anthony W. L.
Published: August 2015

1. The effect of injected ethionine on liver GSH concentrations was studied in male and female rats. 2. Liver GSH concentrations were markedly and consistently decreased in 5hr. and elevated within 24–44hr. By 72hr. the amount of liver GSH of ethionine-poisoned rats had the same values as saline-injected control rats. At no time was erythrocyte GSH concentration affected by ethionine. 3. The concentrations of non-protein thiol compounds, glycogen and ATP were also significantly decreased when the rats were killed 5hr. after ethionine injection. 4. ATP, adenine or methionine did not prevent the decrease of liver GSH produced by ethionine. From these and other observations we conclude that ethionine is not an antagonist of methionine with respect to GSH metabolism. 5. The metabolic relationship between ethionine toxicity and liver GSH concentration is briefly discussed.
The biosynthesis of intestinal mucins. The effect of salicylate on glycoprotein biosynthesis by sheep colonic and human gastric mucosal tissues in vitro
Authors: Kent P W , Allen A.
Published: August 2015

1. Incubation of sheep colonic mucosal scrapings in Krebs–Ringer buffer for 2½hr. in the presence of salicylate (15mm) resulted in decreased incorporation of radioactivity into the epithelial glycoprotein from the following labelled precursors: 16·6μm-d-[2−14C]glucose (83·9% inhibition), 20μm-l-[U−14C]threonine (82%) and 35SO42−(79%). Oxygen uptake measured simultaneously was diminished to 41% of the control value. 2. At lower concentrations of salicylate (e.g. 3·75mm), incorporation of 20μm-l-[U−14C]threonine was little affected (3–6% inhibition), whereas utilization of 4μm-d-[U−14C]glucose and 35SO42− was inhibited (41–48% and 40–59% of the control values respectively). 3. Analysis of the papain-digested glycoprotein from tissue incubations with 16·6μm-d-[2−14C]glucose in the presence of salicylate (3·75mm) showed large decreases in labelling of N-acetylneuraminic acid and N-glycollylneuraminic acid residues (57% and 34% of the control values respectively) and of hexosamine constituents (glucosamine, 55% inhibition; galactosamine, 33% inhibition). Labelling of neutral sugars (galactose and fucose) was relatively little affected (9 and 11% inhibition respectively). 4. Glucose 6-phosphate transaminase and glucosamine 6-phosphate acetylase in particle-free enzyme preparations of the sheep tissue were unaffected by salicylate at the above concentrations. Acetyl-CoA synthetase was markedly inhibited. 5. Human gastric mucosa (from operation), on incubation as above, had in one experiment an oxygen consumption of 9·9μl./hr./mg. dry wt. of tissue and incorporated 5μm-d-[U−14C]glucose (15·8% of the total radioactivity added) into bound hexosamine (20·6% of the total radioactivity incorporated), hexoses (glucose and galactose, 5·7%) and fucose (14·2%). The presence of salicylate (15mm) decreased the incorporation of 5μm-d-[U−14C]glucose into the glycoprotein by 74%, all sugar constituents being affected, without influence on the rate of oxygen consumption. 6. The results suggest an inhibitory effect of salicylate on glycoprotein biosynthesis at the level of the amino sugar intermediates.
Stimulation of pentose phosphate pathway dehydrogenase enzyme activities in ethionine-treated mice
Authors: Sie Hsien-Gieh , Fishman William H.
Published: August 2015

1. Mice treated with ethionine (intraperitoneally, 5mg./day for 4 days or 10mg./day for 3 days) showed a profound loss of hepatic glycogen, a decrease of glycogen synthetase activity, a development of hypoglycaemia, a two- to five-fold increase in the activity of glucose 6-phosphate dehydrogenase but no change in 6-phosphogluconate dehydrogenase and an earlier manifestation of the solubilization of phosphorylase as compared with glycogen synthetase. The administration of ATP did not prevent these effects. 2. During the early post-injection period (2–3 days) there was a further enhancement of the activity of glucose 6-phosphate dehydrogenase (tenfold) in the liver and a clear elevation of 6-phosphogluconate dehydrogenase activity (twofold). Subsequently, the glycogen concentration was restored, followed by an earlier reassociation of glycogen particle with phosphorylase than with glycogen synthetase, along with a disappearance of ethionine effect at about the eighteenth day. 3. Glucose 6-phosphate dehydrogenase from both control and ethionine-treated animals showed a marked preference for glucose 6-phosphate as substrate rather than for galactose 6-phosphate, whose rate of oxidation was only 10% of that of the glucose 6-phosphate. 4. Since actinomycin D, puromycin, 5-fluorouracil and dl-p-fluorophenylalanine failed to block the ethionine-enhanced glucose 6-phosphate dehydrogenase activity, the possibility that new enzyme protein synthesis is responsible for the effect is doubtful.
The biological conversion of 7-dehydrocholesterol into cholesterol and comments on the reduction of double bonds
Authors: Wilton D. C. , Munday K A , Skinner S. J. M. , Akhtar M
Published: August 2015

It is shown that the 7-dehydrocholesterol reductase-catalysed conversion of 7-dehydrocholesterol into cholesterol (II), with a 105000g microsomal pellet of rat liver in the presence of [4−3H2]NADPH, results in the transfer of radioactivity to the 7α-position of cholesterol. When the conversion is carried out in the presence of tritiated water the label is introduced exclusively at the 8β-position. However, when the conversion of 7-dehydrocholesterol into cholesterol is performed with a 500g supernatant of rat liver homogenate the radioactivity is incorporated at both the 7α- and the 8β-position. Evidence is provided for the presence of an enzyme system in the 500g supernatant that catalyses an equilibration of hydrogen atoms between those at the 4-position of NADPH and those of water. The work with stereospecifically labelled cofactors shows that both the equilibrating system and the 7-dehydrocholesterol reductase utilize the 4B-hydrogen atom of NADPH. In the light of these results a mechanism for the reduction of carbon–carbon double bonds is discussed.
Conversion of glutamate into aspartate in guinea-pig cerebral-cortex slices
Authors: Simon Gerald , Cohen M. M. , Berry J. F.
Published: August 2015

1. When guinea-pig cerebral-cortex slices were incubated with [U−14C]glutamate as substrate, the specific radioactivities of the citric acid-cycle intermediates were lower than that of the aspartate isolated from the same vessels. 2. Aspartate was significantly labelled when [5−14C]glutamate was used as substrate and the aspartate contained almost no label when [1−14C]glutamate was present as substrate. 3. When specifically labelled glutamate was used as substrate, the label was found in the isolated aspartate in the position that would be predicted by citric acid-cycle mechanisms. 4. The results are consistent with the theory of ‘compartmentation’ of amino acid metabolism.
Methods for starch-gel electrophoresis of sarcoplasmic proteins. An investigation of the relative mobilities of the glycolytic enzymes from the muscles of a variety of species
Authors: Scopes R. K.
Published: August 2015

1. Details of an improved method for starch-gel electrophoresis of water-soluble muscle proteins are given. 2. Methods are described for detecting enzyme activities on the starch gel after electrophoresis, by using pieces of filter paper. 3. Compositions of incubation mixtures suitable for detecting any of the enzymes of glycolysis, and certain other enzymes, are given. 4. A comparison of the various enzymes in extracts of several muscles from one rabbit was made; most differences are quantitative only. 5. A detailed comparison of the mobilities of various enzymes in extracts of muscles from a wide variety of species was made. Each species was found to have a characteristic pattern of proteins on the starch gel, and the mobilities of individual enzymes varied considerably. 6. Potential uses and extensions of the methods are discussed.
The stepwise removal of histones from chicken erythrocyte nucleoprotein
Authors: Murray K. , Vidali G. , Neelin J. M.
Published: August 2015

1. A fractionation of chicken erythrocyte histones was achieved simultaneously with their extraction from saline-washed nuclei by stepwise titrations to progressively lower pH values. 2. Different acids and dilute buffer solutions of comparable pH behaved similarly in stepwise extractions of histones. 3. The histone preparations so obtained were characterized by their amino acid composition and behaviour on zone electrophoresis in starch gels. 4. The fractionation by titration was quite sharp at appropriate pH ranges, and the histone fraction that is apparently unique to avian erythrocytes was obtained without contamination by other histone fractions. 5. Histones prepared by stepwise titration were fractionated further by cation-exchange and exclusion chromatography. The chromatographic behaviour and amino acid composition of the components permitted comparison with histones prepared by other methods. 6. Histone fraction IIb was resolved into its subfractions IIb1 and IIb2 by exclusion chromatography on Bio-Gel P-60. 7. Histone fractions III and IV, previously reported to be absent from chicken erythrocyte nuclei, were found in extracts made at pH1.
Time-dependence of the effect of X-irradiation on the formation of glycerol phosphate dehydrogenase and other dehydrogenases in the developing rat brain
Authors: De Vellis J. , Schjeide O. A.
Published: August 2015

X-irradiation (100–1500 r) administered to the heads of rats 8–30 days of age inhibited the development of glycerol phosphate dehydrogenase (l-glycerol 3-phosphate–NAD oxidoreductase, EC 1.1.1.8) in the brain stem and cerebral hemispheres. At 40 days of age and older no effect was observed. This inhibition was a delayed phenomenon, dose-dependent and with no recovery. It is proposed that the inhibition of enzyme formation is related to radiation damage caused to DNA. Actinomycin D inhibited the development of glycerol phosphate dehydrogenase in a manner similar to ionizing radiation. Four other dehydrogenases also showed age-dependent radiosensitivities. ‘Malic enzyme’ (EC 1.1.1.40), lactate dehydrogenase (EC 1.1.1.27) and malate dehydrogenase (EC 1.1.1.37) ceased to be radiosensitive at about 8 days of age and isocitrate dehydrogenase (NADP) (EC 1.1.1.42) at 16 days. The correlation between developmental increase in enzyme activity and radiosensitivity held closely for glycerol phosphate dehydrogenase and isocitrate dehydrogenase and to a smaller extent for the others.
The electrophoretic mobility of normal and leukaemic cells of mice
Authors: Cook G. M. W. , Jacobson W.
Published: August 2015

1. The pH–mobility relationships for saline-washed cells from a mouse strain of acute lymphoblastic leukaemia were examined before and after treatment with lower aldehydes, diazomethane and neuraminidase (EC 3.2.1.18). 2. The content of sialic acid released into the supernatant fluid of neuraminidase-treated cells was measured. 3. The stability of the charge-determining structures to temporary changes in environment (pH and ionic strength) was established. 4. Similar measurements were made on lymph-node cells obtained from non-leukaemic mice (a resistant and a leukaemia-susceptible strain were examined). 5. It is deduced that both the malignant and the non-malignant cell possess two dissociable acid functions at the cell surface, a carboxyl group of sialic acid and another acidic group(s), probably carboxyl, of pK 3·0–4·5. The malignant cells, however, have a basic dissociable function not present in the non-malignant types. 6. Suggestions are made as to how the difference in surface chemistry may be related to the problem of malignancy.
A permeability barrier in mitochondria in ‘high-energy states’ against positively charged disulphides
Authors: Skrede S.
Published: August 2015

1. In rat liver mitochondria in state 1 or 4 there is a permeability barrier against cystamine, probably in the inner membrane. 2. The permeability barrier was broken (a) when oxidative phosphorylation was uncoupled, (b) when the respiratory chain was inhibited or in anaerobiosis, or (c) when phosphate was added in the absence of exogenous substrate. Under these conditions increased amounts of [35S]cystamine residues were bound to matrix proteins. 3. It appears that the permeability barrier against cystamine in mitochondria reflects a ‘high-energy state’. A gradual increase in the permeability for cystamine strikingly coincided with the loss of respiratory control induced by increasing concentrations of different uncoupling agents. 4. Cystamine caused uncoupling of oxidative phosphorylation in state 2 or 5, but not in state 1, 3 or 4. The uncoupling effect of cystamine was dependent on the phosphorylation potential. ATP counteracted, whereas ADP potentiated, the uncoupling by cystamine. 5. The variable penetration of cystamine appears to depend on its positive charge, since a dication derivative, NNN′N′-tetramethylcystamine, has a similar pattern of penetration, whereas an uncharged derivative, NN′-diacetylcystamine, penetrates rapidly into mitochondria irrespective of their metabolic state. 6. It is suggested that a charge barrier is present in or across the inner mitochondrial membrane in ‘high-energy states’.
Studies of haemoglobin types in barbary sheep (Ammotragus lervia)
Authors: van Vliet G. , Huisman T. H. J. , Dasher G. A. , Moretz W. H. , Dozy A. M. , Wilson J. B.
Published: August 2015

1. Two haemoglobin types, haemoglobins Amm-C and Amm-B, were observed in five Barbary sheep (Ammotragus lervia). One animal was homozygous for haemoglobin Amm-C, a second was homozygous for haemoglobin Amm-B, and three were heterozygous for both. 2. Amino acid analyses of the globin from haemoglobin Amm-B showed that this type was related to, but not identical with, haemoglobin B of the domestic sheep. 3. The β-chain of haemoglobin Amm-C was found to be composed of 141 amino acid residues. Its amino acid composition differed from that of the βC-chain of the anaemic domestic sheep in at least 14 residues. The Amm-βC-chain contained one isoleucyl residue. 4. The amino acid compositions of tryptic peptides T-1, T-2, T-13 and T-14 of the Amm-βC-chain were similar to those of the sheep βC-chain. Peptides T-3, T-4, T-6, T-7, T-8, T-11 and T-15 were the same as the corresponding peptides of the sheep βA- and βC-chains. Peptide T-5 and to a smaller extent peptide T-9 resembled the corresponding peptides of the sheep βA-chain, and peptide T-10 was identical with peptide γT-10 of sheep haemoglobin F. Peptide T-12 was not recovered. 5. The results of these investigations were interpreted as being indicative that the structural Amm-βC-gene is closely related to the βC-gene of sheep, from which through domestication the present domestic sheep originated.
Acceleration of gluconeogenesis from propionate by dl-carnitine in the rat kidney cortex
Authors: Weidemann M. J. , Krebs H. A.
Published: August 2015

1. The rate of gluconeogenesis from propionate in rat kidney-cortex slices was stimulated up to 3·5-fold by dl-carnitine and by bicarbonate, and was inhibited by inorganic phosphate or high concentrations of propionate (above 3mm). 2. The stimulatory effect of carnitine was dependent on the bicarbonate concentration and could be replaced at low propionate concentration by addition of 25mm-bicarbonate–carbon dioxide buffer. At low bicarbonate concentration the carnitine concentration can be rate-limiting. 3. All observations are in accordance with the view that the action of carnitine is in principle the same as that established for other fatty acids in other tissues, namely that carnitine promotes the appearance of propionyl-CoA within the mitochondrion by acting as a carrier. 4. The accelerating effects of carnitine and bicarbonate and the inhibitory effect of phosphate can be explained on the basis of the known properties of key enzymes of propionate metabolism, i.e. the reversibility of the reactions leading to the formation of methylmalonyl-CoA from propionyl-CoA. 5. 5mm-Propionate caused a five- to ten-fold fall in the free CoA content of the tissue. This fall can account for the inhibition of respiration and gluconeogenesis caused by high propionate concentration. 6. Relatively large quantities of propionyl-l-carnitine (15% of the propionate removed) were formed when dl-carnitine was present; thus the ‘activation’ of propionate proceeded at a faster rate than the carboxylation of propionyl-CoA. The metabolism of added propionyl-l-carnitine was accompanied by glucose synthesis. 7. The appearance of radioactivity from [2−14C]propionate in both glucose and carbon dioxide was as expected on account of the randomization of C-2 and C-3 of propionate, i.e. the formation of succinate as an intermediate. 8. The maximum rate of glucose synthesis from propionate (93·3±3·3μmoles/g. dry wt./hr.) was not affected by dietary changes aimed at varying the rate of caecal volatile fatty acid formation in the rat. 9. Inhibition of gluconeogenesis by high propionate concentration was not found in those species where the rate of caecal or ruminal propionate production is high under normal conditions (rabbit, sheep and cow).
Enzymic degradation of heparin A sulphamidase and a sulphoesterase from Flavobacterium heparinum
Authors: Dietrich Carl P.
Published: August 2015

A sulphamidase and a sulphoesterase were isolated from adapted cells of Flavobacterium heparinum. These enzymes were partially purified from the ‘heparinases’ present in the bacterial extracts and characterized. The sulphamidase has a high specificity for glucosamine N-sulphate and glucosamine 2,6-disulphate. The activity decreases sharply with increasing molecular weight of the substrates tested. The sulphamidase and the sulphoesterase activities were distinguished from each other by their different sensitivities to concentration of phosphate ion and to temperature. The importance of these enzymes in the study of the structure of heparin is discussed.
The foetal development of lactate dehydrogenase isoenzymes, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase from human striated muscle
Authors: Clausen Jørgen , Hustrulid Robert
Published: August 2015

1. Human foetal skeletal muscles involved in support and in periodic contractility were studied for their content of total extractable lactate dehydrogenase, glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities as well as for the relative distribution of lactate dehydrogenase isoenzymes. 2. During foetal development a linear steady increase in total lactate dehydrogenase activity as well as a linear decrease in the H/M sub-unit ratio of the isoenzymes was found. 3. No significant changes were found in the activities of the enzymes of the hexose monophosphate shunt (C-6 oxidation). 4. The changes found suggest a steady increased synthesis of lactate dehydrogenase M-sub-units in human skeletal muscles during foetal development. 5. The weekly changes in the total lactate dehydrogenase activity and in lactate dehydrogenase isoenzymes are lower in muscles involved in support than in those involved in periodic contractility. 6. These findings, together with the literature available, are consistent with the morphological fact that foetal development of skeletal muscles mostly concerns the white muscle fibres and not the red muscle fibres.
Oxoenoic acids as metabolites in the bacterial degradation of catechols
Authors: Bayly R. C. , Dagley S.
Published: August 2015

1. Partially purified extracts of a Pseudomonas converted the meta ring-fission product of 4-methylcatechol into a compound having spectroscopic and chemical properties consistent with its being 2-oxohex-4-enoic acid. 2. Catechol and 3-methylcatechol were both metabolized to a compound that appeared to be 2-oxopent-4-enoic acid. 3. Solutions of norvaline and norleucine were prepared from these metabolites. 4. A reaction scheme is presented for the conversion of catechols into hydroxyoxo acids after meta ring-fission.
Studies in the enzymology of glutathione metabolism in human erythrocytes
Authors: Jackson R. C.
Published: August 2015

Spectrophotometric assay methods are described for glutathione synthetase, γ-glutamylcysteine synthetase and γ-glutamyl transpeptidase of erythrocytes. The contents of these enzymes in normal human erythrocytes are reported. Erythrocyte glutathione synthetase is inhibited by ADP; this inhibition is competitive with respect to ATP. γ-Glutamylcysteine synthetase is subject to feedback inhibition by GSH, and is also inhibited by NADH, and to a lesser extent by NAD+ and NADPH. This enzyme is irreversibly inactivated by cysteamine.
Analogues of geranyl pyrophosphate as inhibitors of prenyltransferase
Authors: Popják G. , Holloway P. W. , Bond R. P. M. , Roberts M.
Published: August 2015

Six analogues of geranyl pyrophosphate (the monophosphates of geraniol and tetrahydrogeraniol, and the pyrophosphates of nerol, octan-1-ol, tetrahydrogeraniol and citronellol) were synthesized, and were found to be inhibitors of pig liver prenyl- (geranyl-)transferase. The effects of each analogue were analysed in kinetic experiments, which showed the pyrophosphates of citronellol, tetrahydrogeraniol and octan-1-ol to be the most potent inhibitors. The results are interpreted to support a previous hypothesis that the main forces in the binding of substrates to prenyltransferase are non-specific lipophilic forces and a pyrophosphate-binding force.