bluuebunny/crossref_metadata_2025 huggingface dataset:
Formulation Strategy for the Delivery of Cyclosporine A: Comparison of Two Polymeric Nanospheres
Authors: Goyal Ritu , Macri Lauren , Kohn Joachim
Published: August 2015

A wide range of nanoparticles has been explored for the delivery of highly hydrophobic drugs, but very few publications provide comparative data of the performance of different nanoparticles. To address this need, this publication compares poly(lactic-co-glycolic acid) (PLGA) nanoparticles and nanospheres made from tyrosine-derived tri-block copolymers (termed TyroSpheres) for their respective performance as carriers for cyclosporine A (CSA). Using previously reported data on PLGA, we followed similar experimental protocols to evaluate the in vitro characteristics of TyroSpheres. Although there are some similarities between the two particle systems for the delivery of CSA, such as effective encapsulation and epidermal skin penetration, several differences were notable. First, the methods of preparation were different, i.e., self-assembly and emulsion-diffusion-evaporation process for TyroSpheres and PLGA, respectively. Second, TyroSpheres provided 7-day diffusion-controlled release, whereas PLGA nanoparticles provided >21-day erosion-controlled release. Third, the size of TyroSpheres was measured to be ~60–70 nm irrespective of drug loading, whereas the size of PLGA nanoparticles (~100–250 nm) was dependent on drug loading and the method of preparation. Overall, this publication provides a direct comparison between two different types of nanoparticles and illuminates the respective advantages and disadvantages, using CSA as a model for the release of highly hydrophobic drugs.
Contribution of Fe3O4 nanoparticles to the fouling of ultrafiltration with coagulation pre-treatment
Authors: Yu Wenzheng , Xu Lei , Graham Nigel , Qu Jiuhui
Published: August 2015

A coagulation (FeCl3)-ultrafiltration process was used to treat two different raw waters with/without the presence of Fe3O4 nanoparticle contaminants. The existence of Fe3O4 nanoparticles in the raw water was found to increase both irreversible and reversible membrane fouling. The trans-membrane pressure (TMP) increase was similar in the early stages of the membrane runs for both raw waters, while it increased rapidly after about 15 days in the raw water with Fe3O4 nanoparticles, suggesting the involvement of biological effects. Enhanced microbial activity with the presence of Fe3O4 nanoparticles was evident from the measured concentrations of extracellular polymeric substances (EPS) and deoxyribonucleic acid (DNA) and fluorescence intensities. It is speculated that Fe3O4 nanoparticles accumulated in the cake layer and increased bacterial growth. Associated with the bacterial growth is the production of EPS which enhances the bonding with and between, the coagulant flocs; EPS together with smaller sizes of the nano-scale primary particles of the Fe3O4-CUF cake layer, led to the formation of a lower porosity, more resilient cake layer and membrane pore blockage.
Elevated β-catenin pathway as a novel target for patients with resistance to EGF receptor targeting drugs
Authors: Nakata Asuka , Yoshida Ryo , Yamaguchi Rui , Yamauchi Mai , Tamada Yoshinori , Fujita Andre , Shimamura Teppei , Imoto Seiya , Higuchi Tomoyuki , Nomura Masaharu , Kimura Tatsuo , Nokihara Hiroshi , Higashiyama Masahiko , Kondoh Kazuya , Nishihara Hiroshi , Tojo Arinobu , Yano Seiji , Miyano Satoru , Gotoh Noriko
Published: August 2015

There is a high death rate of lung cancer patients. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are effective in some lung adenocarcinoma patients with EGFR mutations. However, a significant number of patients show primary and acquire resistance to EGFR-TKIs. Although the Akt kinase is commonly activated due to various resistance mechanisms, the key targets of Akt remain unclear. Here, we show that the Akt-β-catenin pathway may be a common resistance mechanism. We analyzed gene expression profiles of gefitinib-resistant PC9M2 cells that were derived from gefitinib-sensitive lung cancer PC9 cells and do not have known resistance mechanisms including EGFR mutation T790M. We found increased expression of Axin, a β-catenin target gene, increased phosphorylation of Akt and GSK3, accumulation of β-catenin in the cytoplasm/nucleus in PC9M2 cells. Both knockdown of β-catenin and treatment with a β-catenin inhibitor at least partially restored gefitinib sensitivity to PC9M2 cells. Lung adenocarcinoma tissues derived from gefitinib-resistant patients displayed a tendency to accumulate β-catenin in the cytoplasm. We provide a rationale for combination therapy that includes targeting of the Akt-β-catenin pathway to improve the efficacy of EGFR-TKIs.
Nutrition-dependent phenotypes affect sexual selection in a ladybird
Authors: Xie Jiaqin , De Clercq Patrick , Zhang Yuhong , Wu Hongsheng , Pan Chang , Pang Hong
Published: August 2015

Environmental factors play a crucial role in influencing sexual selection in insects and the evolution of their mating systems. Although it has been reported that sexual selection in insects may change in response to varying environments, the reason for these changes remains poorly understood. Here, we focus on the mate selection process of a ladybird, Cryptolaemus montrouzieri, when experiencing low- and high-nutrition diet regimes both in its larval and adult stages. We found that female ladybirds preferred to mate with males reared under high-nutrition diet regimes, regardless of the nutritional conditions they experienced during their own larval stages, indicating that mate choice of female C. montrouzieri is non-random and phenotype-dependent. Such mate choice may depend on visual cues (body or genitalia size) and/or chemical cues (pheromones). Further, females from high-nutrition larval diet regimes produced more eggs than those from low-nutrition larval diet regimes. In addition, diet regimes during adulthood also exerted strong effects on egg production. In summary, our study provides new insight into the mate choice of C. montrouzieri as affected by seasonal changes in resources and suggests that food availability may be a driving force in mate choice.
A highly stable minimally processed plant-derived recombinant acetylcholinesterase for nerve agent detection in adverse conditions
Authors: Rosenberg Yvonne J. , Walker Jeremy , Jiang Xiaoming , Donahue Scott , Robosky Jason , Sack Markus , Lees Jonathan , Urban Lori
Published: August 2015

Although recent innovations in transient plant systems have enabled gram quantities of proteins in 1–2 weeks, very few have been translated into applications due to technical challenges and high downstream processing costs. Here we report high-level production, using a Nicotiana benthamiana/p19 system, of an engineered recombinant human acetylcholinesterase (rAChE) that is highly stable in a minimally processed leaf extract. Lyophylized clarified extracts withstand prolonged storage at 70 °C and, upon reconstitution, can be used in several devices to detect organophosphate (OP) nerve agents and pesticides on surfaces ranging from 0 °C to 50 °C. The recent use of sarin in Syria highlights the urgent need for nerve agent detection and countermeasures necessary for preparedness and emergency responses. Bypassing cumbersome and expensive downstream processes has enabled us to fully exploit the speed, low cost and scalability of transient production systems resulting in the first successful implementation of plant-produced rAChE into a commercial biotechnology product.
Ferutinin as a Ca2+complexone: lipid bilayers, conductometry, FT-IR, NMR studies and DFT-B3LYP calculations
Authors: Dubis A. , Zamaraeva M. V. , Siergiejczyk L. , Charishnikova O. , Shlyonsky V.
Published: August 2015

Spatial re-orientation of two initially H-bonded ferutinin molecules upon Ca2+complexation.
Development of an automated on-chip bead-based ELISA platform
Authors: Campbell Jennifer , Pollock Nira R. , Sharon Andre , Sauer-Budge Alexis F.
Published: August 2015

We present a lab-on-a-chip and associated instrument for heterogeneous enzyme-linked immunosorbent assay (ELISA)-based detection of proteins from liquid samples.
Using silica coated magnetite nanoparticles modified with anionic surfactant aggregates as a solid phase microextraction adsorbent for determination of fluoroquinolones in egg samples by spectrofluorimetry
Authors: Naddaf Ezzat , Ebrahimi Mahmoud , Es'haghi Zarrin , Akhlaghi Hossien
Published: August 2015

A simple and rapid IP-SPME method was developed for extraction and determination of fluoroquinolones. The target analytes were converted into ion pair complexes with SDBS.
Distributed curvature and stability of fullerenes
Authors: Fowler Patrick W. , Nikolić Sonja , De Los Reyes Rasthy , Myrvold Wendy
Published: August 2015

Combinatorial measures of curvature can be used to distinguish stable from unstable fullerenes, and fullerenes from the mass of cubic polyhedral cages.
The effect of structural dimensionality on the electrocatalytic properties of the nickel selenide phase
Authors: Kukunuri Suresh , Krishnan M. Reshma , Sampath S.
Published: August 2015

Synthesis of different morphologies of nickel selenide structures and their activities in various applications.
U@C28: the electronic structure induced by the 32-electron principle
Authors: Dai Xing , Gao Yang , Jiang Wanrun , Lei Yanyu , Wang Zhigang
Published: August 2015

The 32-electron rule can be applied to the neutral U@C28 which contains more than 32 valence electrons.
Interfacial structure and wetting properties of water droplets on graphene under a static electric field
Authors: Ren Hongru , Zhang Leining , Li Xiongying , Li Yifan , Wu Weikang , Li Hui
Published: August 2015

The equilibrium water droplets present a hemispherical, a conical and an ordered cylindrical shape with the increase of external E-field intensity.
Electrochemical electron paramagnetic resonance utilizing loop gap resonators and micro-electrochemical cells
Authors: Tamski Mika A. , Macpherson Julie V. , Unwin Patrick R. , Newton Mark E.
Published: August 2015

A miniaturised electrochemical cell design for Electron Paramagnetic Resonance (EPR) studies utilizing a Loop Gap Resonator is reported.
Unusual non-bifunctional mechanism for Co-PNP complex catalyzed transfer hydrogenation governed by the electronic configuration of metal center
Authors: Hou Cheng , Jiang Jingxing , Li Yinwu , Zhang Zhihan , Zhao Cunyuan , Ke Zhuofeng
Published: August 2015

The unusual non-bifunctional mechanism for CoII-PNP catalyzed transfer hydrogenation is revealed to be governed by the electronic configuration of the metal center, which is different from traditional bifunctional catalysts.
A high performance sulfur-doped disordered carbon anode for sodium ion batteries
Authors: Li Wei , Zhou Min , Li Haomiao , Wang Kangli , Cheng Shijie , Jiang Kai
Published: August 2015

Sulfur-doped disordered carbon exhibits high capacity and excellent cyclability as an anode for sodium ion batteries.
Spatio-temporal impacts of dairy lagoon water reuse on soil: heavy metals and salinity
Authors: Corwin Dennis L. , Ahmad Hamaad Raza
Published: August 2015

Heavy metal and salinity impacts on soil from dairy lagoon water reuse are monitored using geospatial apparent soil electrical conductivity measurements.
The transcriptome of Euglena gracilis reveals unexpected metabolic capabilities for carbohydrate and natural product biochemistry
Authors: O'Neill Ellis C. , Trick Martin , Hill Lionel , Rejzek Martin , Dusi Renata G. , Hamilton Chris J. , Zimba Paul V. , Henrissat Bernard , Field Robert A.
Published: August 2015

Euglena gracilisis a highly complex green alga. In evolutionary terms is most closely related to the protozoan parasitesTrypanosomaandLeishmaniabut it also shows characteristics of both plants and animals.
Facile synthesis of hierarchical porous carbon via the liquidoid carbonization method for supercapacitors
Authors: Li Jiangfeng , Zan Guangtao , Wu Qingsheng
Published: August 2015

A novel honey-derived hierarchical porous carbon for high-performance supercapacitors is synthesized by the liquidoid carbonization and KOH activation method.
An unusual role of folate in the self-assembly of heparin–folate conjugates into nanoparticles
Authors: Wang Jianquan , Ma Daoshuang , Lu Qian , Wu Shaoxiong , Lee Gee Young , Lane Lucas A. , Li Bin , Quan Li , Wang Yiqing , Nie Shuming
Published: August 2015

Tumor targeting agents including antibodies, peptides, and small molecules are often used to improve the delivery efficiency of nanoparticles.
Molecular design of a discrete chain-folding polyimide for controlled inkjet deposition of supramolecular polymers
Authors: Hart Lewis R. , Harries Josephine L. , Greenland Barnaby W. , Colquhoun Howard M. , Hayes Wayne
Published: August 2015

Herein we describe the generation of a well-defined polyimide to afford coloured supramolecular polymer assemblies with electronically complementary pyrenyl terminated polymers which can be inkjet printed.
Biomacrocyclic side-chain liquid crystalline polymers bearing cholesterol mesogens: facile synthesis and topological effect study
Authors: Zhou Feng , Li Yiwen , Jiang Ganquan , Zhang Zhengbiao , Tu Yingfeng , Chen Xiaofang , Zhou Nianchen , Zhu Xiulin
Published: August 2015

Biomacrocyclic side-chain liquid crystalline polymers bearing cholesterol mesogens with three different length methylene spacers were prepared. Meanwhile, the liquid crystalline phase behaviors were investigated systematically.
Exploring the potential of exfoliated ternary ultrathin Ti4AlN3 nanosheets for fabricating hybrid patterned polymer brushes
Authors: Ye Qun , Xiao Peng , Liu Wulong , Chen Ke , Chen Tao , Xue Jianming , Du Shiyu , Huang Qing
Published: August 2015

A new type of ternary Ti4AlN3 nanosheets was prepared for the first time. The obtained sheets with surface groups could be further used to fabricate micro-patterns and subsequently functionalized to achieve hybrid patterned polymer brushes.
α-Lipoic acid protects HAECs from high glucose-induced apoptosis via decreased oxidative stress, ER stress and mitochondrial injury
Authors: Li Wenshuang , Wang Changyuan , Peng Jinyong , Liang Jing , Jin Yue , Liu Qi , Meng Qiang , Liu Kexin , Sun Huijun
Published: August 2015

α-Lipoic acid (LA) has a wide range of benefits in treating diabetes mellitus (DM) and DM vascular diseases, however, the specific mechanisms are not clearly understood.
Spray-on omniphobic ZnO coatings
Authors: Neelakantan Nitin K. , Weisensee Patricia B. , Overcash John W. , Torrealba Eduardo J. , King William P. , Suslick Kenneth S.
Published: August 2015

A simple spray coating of ZnO nanoparticles in PDMS repels water. After functionalizing the coating with fluorosilanes, it also repels oil.
Determination of the ion exchange process of K2Ti4O9 fibers at constant pH and modeling with statistical rate theory
Authors: Liu Chang , Wu Nanhua , Wang Jun , Huang Liangliang , Lu Xiaohua
Published: August 2015

The ion exchange kinetics of K2Ti4O9 fibers at constant pH was determined precisely by ion-selective electrodes, and activity coefficients of ions in solutions were calculated by the Lu–Maurer equation.
Retracted Article: Graphene oxide/DNA-decorated electrode for the fabrication of microRNA biosensor
Authors: Sun Erlin , Wang Lining , Zhou Xiaodong , Ma Chengquan , Sun Yan , Lei Mingde , Lu Bingxin , Han Ruifa
Published: August 2015

A sensitive biosensor for miRNA quantification was fabricated by using a graphene oxide/DNA-decorated electrode.
Catalytic performance of Keplerate polyoxomolybdates in green epoxidation of alkenes with hydrogen peroxide
Authors: Jalilian Fariba , Yadollahi Bahram , Riahi Farsani Mostafa , Tangestaninejad Shahram , Amiri Rudbari Hadi , Habibi Rouhollah
Published: August 2015

The catalytic activity of three Keplerate POM, Mo72M30 (V, Cr and Fe), in the green epoxidation of alkenes with 30% H2O2 in water are investigated. Mo72Cr30 was shown the highest catalytic activity and efficiently reused without any loss of activity.
Inkjet-printed transparent nanowire thin film features for UV photodetectors
Authors: Chen Shih-Pin , Durán Retamal José Ramón , Lien Der-Hsien , He Jr-Hau , Liao Ying-Chih
Published: August 2015

Stable nanowire suspensions are inkjet-printed to form the all-printed transparent UV photodetectors with fast responses.
Measurement of vaporization enthalpy by isothermogravimetrical method and prediction of the polarity for 1-alkyl-3-methylimidazolium acetate {[Cnmim][OAc] (n = 4, 6)} ionic liquids
Authors: Wei Jie , Bu Xiaoxue , Guan Wei , Xing Nannan , Fang Dawei , Wu Yang
Published: August 2015

The ΔglH°m for [Cnmim][OAc] (n = 4, 6) were measured using isothermogravimetrical approach and explored by molecular dynamics simulations. The δμ can be estimated easily, and good agreement with experiences.
Multi-hydroxyl-containing porous organic polymers based on phenol formaldehyde resin chemistry with high carbon dioxide capture capacity
Authors: Jia Shi-Hui , Ding Xuesong , Yu Hai-Tao , Han Bao-Hang
Published: August 2015

Synthesis of multi-hydroxyl-containing porous organic polymers with considerable CO2 capture capability and CO2/N2 selectivity is reported.
Corrosion inhibition effect of spiropyrimidinethiones on mild steel in 15% HCl solution: insight from electrochemical and quantum studies
Authors: Yadav M. , Sinha R. R. , Kumar Sumit , Sarkar T. K.
Published: August 2015

The effect of synthesized spiropyrimidinethiones on the corrosion of mild steel in 15% HCl solution was investigated by using weight loss and electrochemical methods.
Highly ordered monolithic structures by directional freezing and UV-initiated cryopolymerisation. Evaluation as stationary phases in high performance liquid chromatography
Authors: Dario Arrua R. , Hilder Emily F.
Published: August 2015

Rigid aligned polymers were prepared by directional freezing and photo-initiated cryopolymerisation and tested as stationary phases in liquid chromatography.
Recyclable organocatalyst-promoted one-pot Michael/aza-Henry/lactamization reactions for fluorinated 2-piperidinones bearing four stereogenic centres
Authors: Huang Xin , Pham Kenny , Zhang Xiaofeng , Yi Wen-Bin , Hyatt Jeremy H. , Tran Anthony P. , Jasinski Jerry P. , Zhang Wei
Published: August 2015

A highly efficient method for asymmetric synthesis of fluorinated 2-piperidinones bearing four stereogenic centres is introduced.
Lung surfactants and different contributions to thin film stability
Authors: Hermans Eline , Saad Bhamla M. , Kao Peter , Fuller Gerald G. , Vermant Jan
Published: August 2015

In the present work, we investigate the mechanisms affecting the stability of surfactant-laden thin films during spreading, using drainage flows from a hemispherical dome. Three commercial lung surfactant replacements Survanta, Curosurf and Infasurf, along with the phospholipid dipalmitoylphosphatidylcholine (DPPC), are used.
Efficient planar perovskite solar cells using room-temperature vacuum-processed C60 electron selective layers
Authors: Ke Weijun , Zhao Dewei , Grice Corey R. , Cimaroli Alexander J. , Ge Jie , Tao Hong , Lei Hongwei , Fang Guojia , Yan Yanfa
Published: August 2015

A room-temperature vacuum-processed ultra-thin C60 film as a good candidate for electron selective layer for perovskite solar cells.
Superior electrochemical performance of Li3VO4/N-doped C as an anode for Li-ion batteries
Authors: Ni Shibing , Zhang Jicheng , Ma Jianjun , Yang Xuelin , Zhang Lulu
Published: August 2015

A high performance Li3VO4/N-doped C anode was successfully prepared, which shows high specific capacity and excellent cycle performance.
Large-scale aligned crystalline CH3NH3PbI3 perovskite array films
Authors: Li Yitan , Wang Xiao , Wu Shiting , Ci Haina , Xu Henglu , Li Xuemei , Sun Hao , Zhang Zeyao , Cao Anyuan , Guo Xuefeng , Li Yan
Published: August 2015

Owing to the lattice match, large-scale aligned crystalline CH3NH3PbI3 perovskite array films were fabricated on ST cut quartz.
Synergetic enhancement of organic solar cell thermal stability by wire bar coating and light processing
Authors: Tan Ching-Hong , Wong Him Cheng , Li Zhe , Bucknall David G. , Durrant James R. , Cabral João T.
Published: August 2015

OPV film deposition by wire-bar coating and light soaking result in polymer:fullerene solar cells with synergetically enhanced thermal stability.
ZnGeN2 and ZnGeN2:Mn2+ phosphors: hydrothermal-ammonolysis synthesis, structure and luminescence properties
Authors: Shang Mengmeng , Wang Jing , Fan Jian , Lian Hongzhou , Zhang Yang , Lin Jun
Published: August 2015

Yellow-emitting ZnGeN2 and red-emitting ZnGeN2:Mn2+ phosphors were first synthesized by a hydrothermal-ammonolysis reaction.
Synthesis and characterization of color tunable, highly electroluminescent copolymers of polyfluorene by incorporating the N-phenyl-1,8-naphthalimide moiety into the main chain
Authors: Gopikrishna Peddaboodi , Das Dipjyoti , Iyer Parameswar Krishnan
Published: August 2015

Block copolymers of N-phenyl-1,8-naphthalimide (NPN) moiety in the main polyfluorene chain enables the tuning of emission color from blue to green in PLED devices.
Solution-processed p-type copper oxide thin-film transistors fabricated by using a one-step vacuum annealing technique
Authors: Yu Jianmin , Liu Guoxia , Liu Ao , Meng You , Shin Byoungchul , Shan Fukai
Published: August 2015

High-performance p-type CuxO TFTs were fabricated by a solution process and annealed at various temperatures under vacuum.
Steroid metabolism in the cat. Biliary and urinary excretion of metabolites of [4-14C]testosterone
Authors: Archer SEH , Scratcherd T , Taylor W
Published: August 2015

1. [4-(14)C]Testosterone was administered intravenously to anaesthetized male cats as a single injection or as a 45-60min. infusion. 2. Most of the administered radioactivity was excreted in the bile (70-80%); only 2.9-5.5% of the dose was excreted in the urine. 3. Bile and urine samples were hydrolysed successively to yield glucuronide,;cold-acid-hydrolysed′ and; hot-acid-hydrolysed′ fractions. 4. The proportion of glucuronides in bile decreased in successive samples, but cold-and hot-acid-hydrolysed metabolites showed no consistent change. 5. After hydrolysis most of the radioactivity in both bile and urine could not be extracted by ether from neutral aqueous solution.
Protein synthesis in the intestine of goldfish acclimatized to different temperatures
Authors: Morris D. , Smith M. W.
Published: August 2015

1. The incorporation of [(14)C]valine and [(3)H]threonine has been studied in mucosa of goldfish acclimatized to different temperatures. 2. [(14)C]Valine was incorporated more rapidly than [(3)H]threonine at acclimatization temperatures below 15 degrees; this distinction disappeared at higher temperatures. 3. The rate of amino acid incorporation rose as the environmental temperature was increased. 4. The number of valine residues in mucosal protein fell and the number of methionine residues rose as the acclimatization temperature was raised. 5. The concentration of free methionine was closely related to the amount in protein in goldfish mucosa; both increased at higher acclimatization temperatures. 6. An attempt is made to show that these changes are integrated with possible homoeostatic mechanisms in the goldfish intestine.
The site of synthesis of mitochondrial proteins in Krebs II ascites-tumour cells
Authors: Haldar D. , Freeman K. B. , Work T. S.
Published: August 2015

At 22 degrees in Earle's medium, Krebs cells synthesize proteins. After a brief ;pulse' with [(14)C]valine followed by a ;chase' of [(12)C]valine the radioactivity appears first in microsomes and is transferred after ;chase' to the cell sap. Kinetics of labelling of the mitochondrial protein are different from that of either microsomal or cell-sap protein. When Krebs cells in buffer are mixed with ribonuclease in water the nuclease penetrates the cell membrane. The ribonuclease-treated cells are still viable but have lost most of their cytoplasmic ribosomes (electron micrograph). Such cells still synthesize mitochondrial protein at near normal rate but synthesis of microsomal protein is severely inhibited. The results indicate that some mitochondrial proteins are synthesized independently of the microsome-cell-sap system.
Studies on guanine deaminase and its inhibitors in rat tissue
Authors: Kumar S. , Josan V. , Sanger K.C.S. , Tewari K.K , Krishnan P. S.
Published: August 2015

1. In kidney, but not in rat whole brain and liver, guanine-deaminase activity was localized almost exclusively in the 15000g supernatant fraction of iso-osmotic sucrose homogenates. However, as in brain and liver, the enzymic activity recovered in the supernatant was higher than that in the whole homogenate. The particulate fractions of kidney, especially the heavy mitochondria, brought about powerful inhibition of the supernatant guanine-deaminase activity. 2. In spleen, as in kidney, guanine-deaminase activity was localized in the 15000g supernatant fraction of iso-osmotic sucrose homogenates. However, the particulate fractions did not inhibit the activity of the supernatant. 3. Guanine-deaminase activity in rat brain was absent from the cerebellum and present only in the cerebral hemispheres. The inhibitor of guanine deaminase was located exclusively in the cerebellum, where it was associated with the particles sedimenting at 5000g from sucrose homogenates. 4. Homogenates of cerebral hemispheres, the separated cortex or the remaining portion of the hemispheres had significantly higher guanine-deaminase activity than homogenates of whole brain. The enzymic activity of the subcellular particulate fractions was nearly the same. 5. Guanine deaminase was purified from the 15000g supernatant of sucrose homogenates of whole brain. The enzyme separated as two distinct fractions, A and B, on DEAE-cellulose columns. 6. The guanine-deaminase activity of the light-mitochondrial fraction of whole brain was fully exposed and solubilized by treatment with Triton X-100, and partially purified. 7. Tested in the form of crude preparations, the inhibitor from kidney did not act on the brain and liver supernatant enzymes and the inhibitor from cerebellum did not act on kidney enzyme, but the inhibitor from liver acted on both brain and kidney enzyme. 8. The inhibitor of guanine deaminase was purified from the heavy mitochondria of whole brain and liver and the 5000g residue of cerebellum, isolated from iso-osmotic homogenates. The inhibitor appeared to be protein in nature and was heat-labile. The inhibition of the enzyme was non-competitive. 9. Kinetic, immunochemical and electrophoretic studies with the preparations purified from brain revealed that the enzyme from light mitochondria was distinct from enzyme B from the supernatant. A distinction between the two forms of supernatant enzyme was less certain. 10. Guanine deaminase isolated from light mitochondria of brain did not react with 8-azaguanine or with the inhibitor isolated from heavy mitochondria.
Kinetics and mechanism of catalysis by proteolytic enzymes: The kinetics of hydrolysis of derivatives of l-lysine and S-(β-aminoethyl)-l-cysteine(thialysine)by bovine trypsin
Authors: Elmore D. T. , Roberts D. V. , Smyth J.J.
Published: August 2015

1. Several esters of the alpha-N-toluene-p-sulphonyl and N-benzoyl derivatives of l-lysine and S-(beta-aminoethyl)-l-cysteine have been synthesized. 2. The kinetics of hydrolysis of the esters by bovine trypsin have been compared. Values of k(0) are similar for corresponding derivatives of the isosteric amino acids and deacylation of an acyl-enzyme appears to be rate-determining in each case. There are, however, some quantitative kinetic differences between the various series of substrates.
Influence of organic anions on the liberation of penicillinase from Staphylococcus aureus
Authors: Coles N. W. , Gross R.
Published: August 2015

1. A further fraction of ;cell-bound exopenicillinase', in addition to that bound ionically to the surface of the cell wall, has been identified in Staphylococcus aureus. 2. Treatment of cells with low concentrations (0.01m) of organic anions liberates part of this exopenicillinase, such liberation being dependent on both time and temperature, but independent of an external supply of energy. 3. Tricarboxylic acids tend to be more effective than dicarboxylic or monocarboxylic, although there are large differences between ionic species even when tested at the same normalities.
Metabolic changes in human red cells during incubation of whole blood in vitro
Authors: Gomperts B. D.
Published: August 2015

1. Whole blood was incubated at 37 degrees, while being dialysed against a large volume of iso-osmotic bicarbonate buffer, pH7.4. The buffer contained glucose and the essential inorganic components of blood plasma in proportion. 2. After 3hr. of incubation in vitro there is a loss of red-cell 2,3-diphosphoglycerate. 3. Isotope experiments show that this is due to an accelerated rate of destruction of this compound. 4. Simultaneously, there is an increase in the median of red-cell osmotic fragility. 5. After extended periods of incubation there is a decrease in the metabolic rate and a decrease in the ratio of the rates of lactate production to glucose consumption. 6. There is a continuous loss of total adenine nucleotide and, after the first 12hr. of incubation, a tendency for the intracellular Na(+) and K(+) to equilibrate with the plasma. 7. The standard deviation of red-cell osmotic fragility expressed among the red-cell population increases exponentially with the time of incubation.
Amino acid sequences of peptides from a tryptic digest of a urea-soluble protein fraction (U.S.3) from oxidized wool
Authors: Corfield M. C. , Fletcher J. C. , Robson A.
Published: August 2015

1. A tryptic digest of the protein fraction U.S.3 from oxidized wool has been separated into 32 peptide fractions by cation-exchange resin chromatography. 2. Most of these fractions have been resolved into their component peptides by a combination of the techniques of cation-exchange resin chromatography, paper chromatography and paper electrophoresis. 3. The amino acid compositions of 58 of the peptides in the digest present in the largest amounts have been determined. 4. The amino acid sequences of 38 of these have been completely elucidated and those of six others partially derived. 5. These findings indicate that the parent protein in wool from which the protein fraction U.S.3 is derived has a minimum molecular weight of 74000. 6. The structures of wool proteins are discussed in the light of the peptide sequences determined, and, in particular, of those sequences in fraction U.S.3 that could not be elucidated.
The reaction of iodobenzene-p-sulphonyl chloride (pipsyl chloride) with certain amino acids and peptides, and with insulin
Authors: Fletcher J. C.
Published: August 2015

1. A system of separation using buffered Celite columns is described that enables the pipsyl derivatives of most of the common amino acids to be separated. 2. The reaction of pipsyl chloride with several amino acids not included in previous studies has been investigated. In particular, knowledge of the acid-soluble pipsyl derivatives of arginine, histidine, lysine, tyrosine and cysteic acid has been extended. 3. Reproducible factors have been obtained that enable corrections to be applied for the breakdown of pipsylamino acids on acid hydrolysis. 4. The reaction of pipsyl chloride with peptides has been studied under various conditions. 5. The extent of the reaction between pipsyl chloride and insulin depends on the nature of the solvent-buffer system, and under the best conditions so far found is about 75% complete. 6. In an Appendix, the separation of pipsylamino acids by thin-layer chromatography is described.
The synergistic decarboxylation of glyoxylate and 2-oxoglutarate by an enzyme system from pig-liver mitochondria
Authors: Stewart P. R. , Quayle J. R.
Published: August 2015

1. An enzyme system that catalyses a synergistic decarboxylation of glyoxylate and 2-oxoglutarate has been purified from pig-liver mitochondria. 2. The purified system is specific for glyoxylate and 2-oxoglutarate as substrates, although in earlier stages of purification glycine and l-glutamate are also active. 3. The reaction is inhibited strongly by EDTA and N-ethylmaleimide. Substrate analogues, present at concentrations equimolar with respect to the substrates, are not effective as inhibitors. 4. The reaction proceeds in the absence of added cofactors. Magnesium chloride, mercaptoethanol and sucrose stimulate the reaction, and stabilize the activity of the enzyme. 5. The pH optimum of the reaction is 7.0. The K(m) values of glyoxylate and 2-oxoglutarate, at saturating concentration of the corresponding co-substrate, are 16mm and 3.6mm respectively. 6. Isotopic work with specifically labelled [(14)C]glyoxylate and 2-oxo[(14)C]-glutarate suggests that the enzyme system catalyses an initial condensation of glyoxylate and 2-oxoglutarate that results in, or leads to, release of C-1 of both substrates as carbon dioxide. C-2 of glyoxylate and C-5 of 2-oxoglutarate do not appear as carbon dioxide. 7. The stoicheiometry of the reaction is complex. During the initial stages of the reaction, more carbon dioxide is recovered from 2-oxoglutarate than from glyoxylate. Subsequently, there is a disproportionate increase with time of carbon dioxide evolution from the carboxyl group of glyoxylate. The excess of decarboxylation of glyoxylate over 2-oxogluturate is further increased by treatment of reaction products with acid.
Sulphation as a metabolic pathway for oestradiol in the sea urchin Strongylocentrotus franciscanus
Authors: Creange John E. , Szego Clara M.
Published: August 2015

1. Aerobic incubation of [(14)C]oestradiol, in the presence of surviving gut tissue of the sea urchin Strongylocentrotus franciscanus, or a soluble enzyme system prepared therefrom, resulted in rapid formation of a water-soluble metabolite, identified as oestradiol 3-sulphate. 2. No evidence was obtained for the formation of other metabolic derivatives by the urchin-gut enzymes, or for the presence of the sulphating capacity in any other tissues of the organism under the conditions used. 3. The data are consistent with the possibility that oestradiol, previously detected in the gonads, is synthesized therein and excreted in a conjugated, highly water-soluble form via the gut.
Measurement of the arylsulphatase of Patella vulgata with 4-methylumbelliferone sulphate
Authors: Sherman W. R. , Stanfield E. F.
Published: August 2015

1. The preparation, purification, chemical and spectral properties of potassium 4-methylumbelliferone sulphate are described. 2. The use of 4-methylumbelliferone sulphate as a substrate for the arylsulphatase of Patella vulgata is presented with specific reference to the fluorimetric assay procedure used with this substrate. 3. 4-Methylumbelliferone sulphate is compared with the previously used synthetic sulphatase substrates nitrocatechol sulphate and p-nitrophenyl sulphate with respect to K(m), V(max.) and sensitivity in the assay of arylsulphatase. 4. 4-Methylumbelliferone sulphate was strongly inhibited by phosphate. Sulphate, a less potent inhibitor, appeared to be of the competitive type with some anomalous characteristics.
Inhibition of the orthophosphatase and pyrophosphatase activities of human alkaline-phosphatase preparations
Authors: Eaton R.H. , Moss D. W.
Published: August 2015

1. Inhibition of the pyrophosphatase and orthophosphatase activities of human liver and small-intestinal alkaline-phosphatase preparations by different classes of inhibitors has been studied. 2. Each type of substrate, pyrophosphate or orthophosphate, is a competitive inhibitor of hydrolysis of the other type. 3. l-Phenylalanine is a non-competitive inhibitor of both types of activity of the intestinal preparation, but inhibits neither activity of the liver enzyme. Arsenate is a competitive inhibitor of both activities of both preparations. For a given inhibitor, the values of K(i) are independent of the type of substrate used when measurements are made at the same pH. 4. Mg(2+) ions activate orthophosphatase but inhibit pyrophosphatase, except in very low concentrations. 5. These results are compatible with the presence in each tissue preparation of a single enzyme with one type of active centre, possessing both orthophosphatase and pyrophosphatase activities.
The secretion of newly synthesized insulin in vitro
Authors: Howell S. L. , Taylor K. W.
Published: August 2015

1. An immunological method for the purification of small quantities of insulin has been devised. 2. This method has been used to isolate labelled insulin secreted from pancreas slices incubated in vitro. The insulin had previously been labelled by incubation of the slices with [(3)H]leucine in vitro. 3. There is some release of labelled insulin when such slices are further incubated in media of low glucose content. When the glucose content of the medium is raised, little additional radioactive insulin is released in the first hour after labelling. However, there is a marked increase in specific radioactivity of insulin released from slices in response to a high concentration of glucose in the second and third hours. Release of labelled insulin is again diminished in the final phase, 4hr. from the start of the experiment. 4. These results are discussed in relation to possible mechanisms of insulin release from the beta-cell.
Inhibition of glycosidases by aldonolactones of corresponding configuration: Preparation of (1→5)-lactones by catalytic oxidation of pyranoses and study of their inhibitory properties
Authors: Conchie J. , Hay A. J. , Strachan I. , Levvy G. A.
Published: August 2015

1. A method was devised for the preparation of (1-->5)-lactones from pyranose sugars and uronic acids by platinum-catalysed oxidation with gaseous oxygen in aqueous solution at acid pH. It was applied to mannose, N-acetylglucosamine, N-acetylgalactosamine, glucuronic acid, galacturonic acid, galactose, l-arabinose and d-fucose. 2. Only the first three yielded products that could be obtained in the solid state without decomposition. In every case, however, the oxidation product in aqueous solution behaved as the aldono-(1-->5)-lactone, and was more inhibitory towards the appropriate glycosidases than any aldonolactone preparation hitherto examined. 3. The stabilities of the oxidation products were studied, and their interconversion with the (1-->4)-lactones was demonstrated. Ring-opening does not appear to be mandatory for this isomeric change, which in some instances is very rapid. 4. To explain all the inhibitory effects observed with aldonolactones on glycosidases of corresponding configuration, it is tentatively postulated that inhibition may be due entirely to the (1-->5)-lactone, and that any inhibitory effect seen with the (1-->4)-lactone is a measure of the extent and speed of its conversion into the (1-->5)-lactone in aqueous solution.
The ion-binding characteristics of reconstituted collagen
Authors: Weinstock A. , King P. C. , Wuthier R. E.
Published: August 2015

The ion-binding capacity of highly purified reconstituted calf-skin collagen, and the effects of these ions on the precipitation and solubility of the collagen, were studied with a variety of salt solutions at ionic strength 0.16 and pH7.4. Only a small percentage of the total theoretically available anionic and cationic groups was available for ion-binding. In view of this, it appears that most of the ionizable groups of collagen are involved in intramolecular or intermolecular linkages, or both. Nevertheless, marked differences in the binding of the various ions by collagen were observed. Bivalent cations were bound in extremely small but remarkably similar quantities. In contrast, sodium was bound both in much higher and more variable quantities. Of the anions, pyrophosphate and sulphate were bound in the largest quantities, followed by phosphate, fluoride and chloride, in that order. Despite the minimal uptake by collagen of bivalent cations, they prevented the aggregation of tropocollagen into fibrils, and disaggregated fibrillar collagen. In the presence of multivalent anions, tropocollagen aggregated readily and its fibrillar stability was maintained. On the basis of the imbalance in the binding of ion pairs by the sodium pyrophosphate- and sodium phosphate-treated collagens, it was apparent that a reduced number of side-chain carboxyl groups were dissociated in the presence of these salts.
Incorporation of dl-[2−14C]mevalonic acid lactone into β-carotene and the phytol side chain of chlorophyll in cotyledons of four species of pine seedlings
Authors: Wieckowski S. , Goodwin T W
Published: August 2015

1. The incorporation of dl-[2−14C]mevalonic acid lactone into β-carotene and the phytol side chain of chlorophyll has been investigated in cotyledons of four species of pine seedlings (Pinus silvestris, P. contorta, P. radiata and P. jeffrei) grown in darkness and in light. 2. The relative incorporation of label into β-carotene and the phytol side chain of chlorophyll is similar to that observed in experiments on monocotyledons and dicotyledons. 3. The relative incorporation of 14CO2 into β-carotene and phytol is much higher than the incorporation of [2−14C]mevalonic acid.
Influence of some aliphatic alcohols on the metabolism of rat liver slices
Authors: Forsander Olof A.
Published: August 2015

The influence of some aliphatic alcohols on oxygen uptake, carbon dioxide production, acid formation and lactate and pyruvate concentrations of rat liver slices was studied. At the concentrations used, none of the alcohols was found to influence oxygen uptake. Of the alcohols that are not oxidized by liver alcohol dehydrogenase, methanol increased carbon dioxide production, propan-2-ol decreased it and 2-methylpropan-2-ol was without influence. All the alcohols that are oxidized by the enzyme strongly decreased carbon dioxide production. The alcohols that are not oxidized had no marked effect on the lactate/pyruvate concentration ratio, whereas the other alcohols strongly increased the ratio. A highly significant correlation was found between the effects of the alcohol on pyruvate concentration and carbon dioxide production. It is assumed that the shift in the redox potential inhibits the function of the tricarboxylic acid cycle of the liver.
The purification and properties of N-acetylglucosamine 6-phosphate deacetylase from Escherichia coli
Authors: White R. J. , Pasternak C A
Published: August 2015

1. N-Acetylglucosamine 6-phosphate deacetylase and 2-amino-2-deoxy-d-glucose 6-phosphate ketol-isomerase (deaminating) (EC 5.3.1.10, glucosamine 6-phosphate deaminase) of Escherichia coliK12 have been separated by chromatography on DEAE-cellulose. 2. N-Acetylglucosamine 6-phosphate deacetylase has optimum pH8·5 and Km 0·8mm. Glucosamine 6-phosphate is a product of the reaction. There appear to be no essential cofactors. Glucosamine 6-phosphate and fructose 6-phosphate inhibit deacetylation. 3. Glucosamine 6-phosphate deaminase has optimum pH7·0 and Km 9·0mm. It is stimulated by N-acetylglucosamine 6-phosphate. 4. We propose that the deacetylase be termed 2-acetamido-2-deoxy-d-glucose 6-phosphate amidohydrolase (EC 3.5.1.–), with acetylglucosamine 6-phosphate deacetylase as a trivial name.
Effect of pH on inhibition and spontaneous reactivation of acetylcholinesterase treated with esters of phosphorus acids and of carbamic acids
Authors: Reiner Elsa , Aldridge W. N.
Published: August 2015

1. The second-order rate constants of inhibition, ka, of acetylcholinesterase were measured at pH values between 5·5 and 10·5 for two esters of phosphorus acids and five esters of carbamic acids. Two of the carbamates and one of the phosphates contained a quaternary nitrogen group. 2. For the three positively charged compounds the ka–pH plots are bell-shaped, with a pH optimum between 7·5 and 9·0. The changes in ka above and below the optimum pH fit theoretical curves for the dissociation of groups on the protein of pK 6·2 and 10·25. 3. For the uncharged compounds, the ka–pH plot on the alkaline side is identical with the one obtained for charged inhibitors. On the acid side they do not fit such a curve and the ka for two of the carbamates is independent of pH changes between 5·5 and 8·0. 4. The first-order rate constants, k+3, for spontaneous reactivation were measured at pH values between 5·0 and 11·0 for N-methylcarbamoylated, NN-dimethylcarbamoylated and di-(2-chloroeth)phosphorylated cholinesterase. For all three derivatives the k+3–pH plots are bell-shaped, with a pH optimum between 8·0 and 8·5. The changes in k+3 above and below the optimum fit theoretical curves for the dissociation of groups of pK 6·9 and 9·8. 5. The relevance of these results to binding, acylation and deacylation of both inhibitors and substrates is discussed.
Incorporation of [2−14C]mevalonic acid into phytoene by isolated chloroplasts
Authors: Charlton Josephine M. , Treharne K J. , Goodwin T W
Published: August 2015

1. Chloroplasts prepared by the non-aqueous technique will, after fragmentation by ultrasonic treatment, incorporate [2−14C]mevalonic acid into phytoene, the first C40 compound formed in the biosynthetic sequence to coloured carotenoids. 2. With suspensions containing 3·5mg. of chlorophyll, the optimum amounts of cofactor required were ATP (10μmoles), magnesium chloride (20μmoles) and glutathione (20μmoles); neither NAD+ nor NADP+ was required. 3. Very small amounts of squalene are also formed and synthesis is stimulated by addition of NADH or NADPH. Phytoene synthesis was not affected by the presence of these cofactors and no lycopersene (the C40 homologue of squalene) was detected. 4. The phytol side chain of chlorophyll is also labelled under these conditions. 5. Preparations of developing chloroplasts are more active than preparations of mature chloroplasts.
Properties of steroid sulphatase and arylsulphatase activities of human placenta
Authors: French Alfred P. , Warren James C.
Published: August 2015

1. The properties of enzyme activities hydrolysing the sulphate esters of dehydroepiandrosterone, oestrone and p-nitrophenol are reported. The preparation studied was obtained from the microsomal fraction of human placenta by ultrasonic treatment and addition of Triton X-100. 2. The behaviour of the preparation during sedimentation at 105000g and attempts at purification indicated that the activities were particulate. Electron microscopy demonstrated the rupture of vesicular structures approx. 0·5μ in diameter concurrent with the release of activity. 3. The three activities were always associated throughout repeated attempts at separation by sucrose-density-gradient centrifugation and Sephadex-gel filtration. On the basis of kinetic studies, stability studies and treatment with butanol and ribonuclease it was concluded that a separate enzyme is responsible for each of the three activities. Widely varying plots of activity as a function of pH were consistent with this conclusion. 4. On the basis of sensitivity of the enzymes hydrolysing dehydroepiandrosterone sulphate and oestrone sulphate to ribonuclease and sensitivity of all three enzymes to lipase, it was concluded that the three enzymes are bound to a particle containing lipid and RNA. Enzymic activity is dependent on structural integrity of the particle. 5. A spectrophotometric method for the assay of oestrone sulphate hydrolysis is described. 6. Hydrolysis of nitrocatechol sulphate by human placenta under conditions described for arylsulphatases A and B is reported.