bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oligomerization of the human immunodeficiency virus type 1 (HIV-1) Vpu protein – a genetic, biochemical and biophysical analysis
Authors: Hussain Amjad , Das Suman R , Tanwar Charu , Jameel Shahid 
Published: August 2007

Abstract

Background
The human immunodeficiency virus type 1(HIV-1) is a complex retrovirus and the causative agent of acquired immunodeficiency syndrome (AIDS). The HIV-1 Vpu protein is an oligomeric integral membrane protein essential for particle release, viral load and CD4 degradation. In silico models show Vpu to form pentamers with an ion channel activity.

Results
Using Vpu proteins from a primary subtype C and the pNL4-3 subtype B isolates of HIV-1, we show oligomerization of the full-length protein as well as its transmembrane (TM) domain by genetic, biochemical and biophysical methods. We also provide direct evidence of the presence of Vpu pentamers in a stable equilibrium with its monomers in vitro. This was also true for the TM domain of Vpu. Confocal microscopy localized Vpu to the endoplasmic reticulum and Golgi regions of the cell, as well as to post-Golgi vesicles. In fluorescence resonance energy transfer (FRET) experiments in live cells we show that Vpu oligomerizes in what appears to be either the Golgi region or intracellular vesicles, but not in the ER.

Conclusion
We provide here direct evidence that the TM domain, is critical for Vpu oligomerization and the most favourable channel assembly is a pentamer. The Vpu oligomerization appears to be either the Golgi region or intracellular vesicles, but not in the ER.
Disruption and pseudoautosomal localization of the major histocompatibility complex in monotremes
Authors: Dohm Juliane C , Tsend-Ayush Enkhjargal , Reinhardt Richard , Grützner Frank , Himmelbauer Heinz 
Published: August 2007

Abstract
Background
The monotremes, represented by the duck-billed platypus and the echidnas, are the most divergent species within mammals, featuring a flamboyant mix of reptilian, mammalian and specialized characteristics. To understand the evolution of the mammalian major histocompatibility complex (MHC), the analysis of the monotreme genome is vital.

Results
We characterized several MHC containing bacterial artificial chromosome clones from platypus (Ornithorhynchus anatinus) and the short-beaked echidna (Tachyglossus aculeatus) and mapped them onto chromosomes. We discovered that the MHC of monotremes is not contiguous and locates within pseudoautosomal regions of two pairs of their sex chromosomes. The analysis revealed an MHC core region with class I and class II genes on platypus and echidna X3/Y3. Echidna X4/Y4 and platypus Y4/X5 showed synteny to the human distal class III region and beyond. We discovered an intron-containing class I pseudogene on platypus Y4/X5 at a genomic location equivalent to the human HLA-B,C region, suggesting ancestral synteny of the monotreme MHC. Analysis of male meioses from platypus and echidna showed that MHC chromosomes occupy different positions in the meiotic chains of either species.

Conclusion
Molecular and cytogenetic analyses reveal new insights into the evolution of the mammalian MHC and the multiple sex chromosome system of monotremes. In addition, our data establish the first homology link between chicken microchromosomes and the smallest chromosomes in the monotreme karyotype. Our results further suggest that segments of the monotreme MHC that now reside on separate chromosomes must once have been syntenic and that the complex sex chromosome system of monotremes is dynamic and still evolving.
Comparative genomic analysis of the Tribolium immune system
Authors: Zou Zhen , Evans Jay D , Lu Zhiqiang , Zhao Picheng , Williams Michael , Sumathipala Niranji , Hetru Charles , Hultmark Dan , Jiang Haobo 
Published: August 2007

Abstract
Background
Tribolium castaneum is a species of Coleoptera, the largest and most diverse order of all eukaryotes. Components of the innate immune system are hardly known in this insect, which is in a key phylogenetic position to inform us about genetic innovations accompanying the evolution of holometabolous insects. We have annotated immunity-related genes and compared them with homologous molecules from other species.

Results
Around 300 candidate defense proteins are identified based on sequence similarity to homologs known to participate in immune responses. In most cases, paralog counts are lower than those of Drosophila melanogaster or Anopheles gambiae but are substantially higher than those of Apis mellifera. The genome contains probable orthologs for nearly all members of the Toll, IMD, and JAK/STAT pathways. While total numbers of the clip-domain serine proteinases are approximately equal in the fly (29), mosquito (32) and beetle (30), lineage-specific expansion of the family is discovered in all three species. Sixteen of the thirty-one serpin genes form a large cluster in a 50 kb region that resulted from extensive gene duplications. Among the nine Toll-like proteins, four are orthologous to Drosophila Toll. The presence of scavenger receptors and other related proteins indicates a role of cellular responses in the entire system. The structures of some antimicrobial peptides drastically differ from those in other orders of insects.

Conclusion
A framework of information on Tribolium immunity is established, which may serve as a stepping stone for future genetic analyses of defense responses in a nondrosophiline genetic model insect.
Effect of Macronutrient Composition on Postprandial Peptide YY Levels
Authors: Essah Paulina A. , Levy James R. , Sistrun Sakita N. , Kelly Susan M. , Nestler John E. 
Published: August 2007

Abstract
Background: Peptide YY (PYY) is released from the distal small intestine and colon after meals and reduces appetite by increasing satiety. The amount of PYY released is proportional to calories ingested. Fat ingestion has also been reported to stimulate PYY release.
Objective: The objective of the study was to determine whether macronutrient composition influences postprandial serum PYY levels by comparing 1 wk of a weight-maintenance low-carbohydrate, high-fat (LCHF) diet with a low-fat, high-carbohydrate (LFHC) diet.
Methods: In this randomized crossover study, 18 obese subjects (14 females, 4 males, mean body mass index 35.6 ± 2.9 kg/m2) were randomly assigned initially to 1 wk of a weight-maintenance LCHF or LFHC diet, after which a test meal of identical composition was given and serum PYY levels were assessed for 2.5 h postprandially. After a 1-wk washout period, subjects were crossed over and retested.
Results: After 1 wk, mean postprandial area under the curve PYY after the LCHF test meal was 1.5-fold greater than after the LFHC test meal (P &lt; 0.001). The LCHF diet led to 55% higher levels of postprandial serum PYY levels, compared with the LFHC diet (P = 0.005).
Conclusions: These data show that a LCHF diet stimulates PYY secretion more than a LFHC diet in obese individuals.
Effect of Iodide on Human Choriogonadotropin, Sodium-Iodide Symporter Expression, and Iodide Uptake in BeWo Choriocarcinoma Cells
Authors: Li Huika , Richard Kerry , McKinnon Brett , Mortimer Robin H. 
Published: August 2007

Abstract
Context: Active placental transport of maternal iodide by the thyroidal sodium iodide symporter (NIS) provides an essential substrate for fetal thyroid hormone synthesis. NIS is expressed in trophoblast and is regulated by human choriogonadotropin (hCG). In thyroid, iodide down-regulates expression of several genes including NIS. Placentas of iodine-deficient rats demonstrate up-regulation of NIS mRNA, suggesting a role for iodide in regulating placental NIS.
Objectives and Methods: The objectives were to examine effects of iodide on expression of NIS and hCG in BeWo choriocarcinoma cells. Gene expression was studied by quantitative real-time PCR. Effects on NIS protein expression were assessed by Western blotting. Functional activity of NIS was measured by 125I uptake. Expression of hCG protein was assessed by immunoassay of secreted hormone.
Results: Iodide inhibited NIS mRNA and membrane protein expression as well as 125I uptake, which were paralleled by decreased βhCG mRNA expression and protein secretion. Iodide had no effects on pendrin expression. Addition of hCG increased NIS mRNA expression. This effect was partially inhibited by addition of iodide. The inhibitory effects of iodide on NIS mRNA expression were abolished by propylthiouracil and dithiothreitol.
Conclusions: We conclude that expression of placental NIS is modulated by maternal iodide. This may occur through modulation of hCG effects on NIS and hCG gene expression.
Body Mass Index Predicts Aldosterone Production in Normotensive Adults on a High-Salt Diet
Authors: Bentley-Lewis Rhonda , Adler Gail K. , Perlstein Todd , Seely Ellen W. , Hopkins Paul N. , Williams Gordon H. , Garg Rajesh 
Published: August 2007

Abstract
Context: The mechanisms underlying obesity-mediated cardiovascular disease are not fully understood. Aldosterone and insulin resistance both are associated with obesity and cardiovascular disease.
Objectives: The objectives of this study were to test the hypotheses that aldosterone production is elevated and associated with insulin resistance in overweight adults on a high-sodium diet.
Participants/Interventions: Healthy normotensive adults were categorized as lean body mass index (BMI) less than 25 kg/m2 (n = 63) or overweight BMI 25 kg/m2 or greater (n = 57). After 7 d of a high-sodium diet, participants fasted overnight and remained supine throughout hemodynamic and laboratory assessments and angiotensin II (AngII) stimulation.
Results: The overweight group, compared with the lean group, had higher 24-h urinary aldosterone (9.0 ± 0.8 vs. 6.6 ± 0.5 μg per 24 h; P = 0.003) and higher AngII-stimulated serum aldosterone (11.4 ± 1.0 vs. 9.0 ± 0.6 ng/dl; P = 0.04). There were no differences in 24-h urinary cortisol or sodium or supine measurements of plasma renin activity, serum aldosterone, or serum potassium. The homeostasis model assessment of insulin resistance was predicted by urinary aldosterone excretion (r = 0.32, P = 0.03) and serum aldosterone response to AngII stimulation (r = 0.28, P = 0.02) independent of age and BMI.
Conclusion: Urinary aldosterone excretion and AngII-stimulated aldosterone are increased in overweight, compared with lean, normotensive adults. The correlation of these measures of aldosterone production with insulin resistance suggests a potential role for aldosterone in the pathophysiology of obesity-mediated insulin resistance.
Matrix metalloprotease-2 and -9 concentration and activity in serum and culture medium samples: a methodological reappraisal
Authors: Colotti Chiara , Angeli Valeria , Del Ry Silvia , Maltinti Maristelli , Vittorini Simona , Giannessi Daniela 
Published: August 2007

AbstractClin Chem Lab Med 2007;45:1292–8.
Microhardness and microstructure of deciduous enamel with different types of amelogenesis imperfecta
Authors: Pavlič Alenka , Škraba Polona , Kosec Ladislav , Petelin Milan , Alaluusua Satu 
Published: August 2007

Abstract
Amelogenesis imperfecta (AI) is an inherited tooth disorder with widely varying phenotypes. The aim of this study was to determine the microhardness and microstructure characteristics of the enamel in AI teeth. The AI phenotypes examined were hypoplastic (pitted and smooth form), hypomaturated, and hypocalcified. Six AI patients were diagnosed according to clinical characteristics. The microhardness of the enamel was measured on axial cuts of AI teeth acquired from the patients. The measurements were done on several sites from the enamel surface towards the dentine-enamel junction using the Vickers scale. Values of microhardness were compared to corresponding control teeth. The microstructure of AI enamel types was evaluated using scanning electron microscopy. The values of microhardness in pitted hypoplastic AI samples were, on average, lower compared to the control enamel and dropped markedly towards the dentine-enamel junction. The smooth hypoplastic enamel was not only extremely thin but also much softer than control enamel. The values for hypomaturated AI fluctuated, but the palatal sites were markedly softer than in the control tooth. Hypocalcified enamel was the softest, with values resembling those of dentin. Microstructural changes varied from altered orientation of enamel prisms in pitted hypoplastic AI to lack of normal prismatic structure and severe porosity in hypocalcified AI. The present results suggest different microhardness profiles and microstructures in each phenotype. Variations among phenotypes are expected with larger case selection in this genetically heterogeneous disease.
Cover Picture: Effect of Water Filling on the Electronic and Vibrational Resonances of Carbon Nanotubes: Characterizing Tube Opening by Raman Spectroscopy (Adv. Mater. 17/2007)
Authors: Wenseleers W. , Cambré S. , Čulin J. , Bouwen A. , Goovaerts E. 
Published: August 2007

AbstractClosed (empty) and opened (water‐filled) single‐walled carbon nanotubes (SWNTs), such as the (12,1) SWNTs shown (foreground), can be clearly resolved in 2D Raman maps (background) of bile salt solubilized SWNTs in water, report Wim Wenseleers and co‐workers on p. 2274. While being of fundamental interest, this also provides a method to monitor tube opening/closing under various treatments (insets, left to right: as‐produced; mechanically treated; chemically treated; reclosed SWNTs by annealing).
Copper‐Catalyzed Enantioselective Conjugate Addition of Organometallic Reagents to Acyclic Dienones
Authors: Šebesta Radovan , Pizzuti M. Gabriella , Minnaard Adriaan J. , Feringa Ben L. 
Published: August 2007

AbstractThe enantioselective, copper/phosphoramidite‐catalyzed 1,4‐addition of dialkylzinc reagents to acyclic dienones is described. The products of this reaction, obtained with enantioselectivities of up to 95 %, can be further functionalized by a second conjugate addition, or employed in an enolate trapping, ring‐closing metathesis protocol.
Catalysis in Water: Aldol‐Type Reaction of Aldehydes and Imines with Ethyl Diazoacetate Catalyzed by Highly Basic Magnesium/Lanthanum Mixed Oxide
Authors: Kantam M. Lakshmi , Balasubrahmanyam V. , Kumar K. B. Shiva , Venkanna G. T. , Figueras F. 
Published: August 2007

AbstractMagnesium/lanthanum mixed oxide is an effective heterogeneous catalyst for aldol‐type condensation of aldehydes and imines with ethyl diazoacetate (EDA) at room temperature in water to afford corresponding β‐hydroxy‐α‐diazo carbonyl compounds and β‐amino‐α‐diazo carbonyl compounds in good yields. The catalyst is recovered and reused for several cycles with consistent activity.
Regioselective Hydrolysis of Different Peracetylated β‐Monosaccharides by Immobilized Lipases from Different Sources. Key Role of The Immobilization
Authors: Palomo Jose M. , Filice Marco , Fernandez‐Lafuente Roberto , Terreni Marco , Guisan Jose M. 
Published: August 2007

AbstractThe effect of the immobilization strategy on the activity, specificity and regioselectivity of three different lipases [those from Thermomyces lanuginose (TLL), Aspergillus niger (ANL) and Candida antarctica B (CAL‐B)] in the hydrolysis of peracetylated β‐monosaccharides has been evaluated. Three very different immobilization strategies were utilized, covalent attachment, anionic exchange and interfacial activation on a hydrophobic support. The octyl‐TLL immobilized preparation was the most efficient biocatalyst in the hydrolysis of 1,2,3,4,6‐penta‐O‐acetyl‐β‐D‐galactopyranose, producing specifically 6‐hydroxy‐1,2,3,4‐tetra‐O‐acetyl‐β‐D‐galactopyranose in 95 % overall yield, whereas the CNBr‐TLL preparation was 48 times slower and regioselective towards the anomeric position, producing the 1‐hydroxy derivative in 70 % yield. The PEI‐TLL immobilized preparation was the most efficient catalyzing the hydrolysis of 1,2,3,4,6‐penta‐O‐acetyl‐β‐D‐glucopyranose, permitting us to obtain up to 70 % of the 6‐hydroxy product. In the hydrolysis of 2‐acetamido‐2‐deoxy‐1,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranose, the octyl‐CALB preparation was not selective at all for the production of monohydroxy products whereas when CAL‐B was immobilized on PEI‐agarose, the enzyme was highly specific and regioselective producing the 6‐hydroxy‐2‐acetamido‐2‐deoxy‐1,3,4‐tri‐O‐acetyl‐β‐D‐glucopyranose in 70 % yield.
Asymmetric Baeyer–Villiger Biooxidation of α‐Substituted Cyanocyclohexanones: Influence of the Substituent Length on Regio‐ and Enantioselectivity
Authors: Berezina Nathalie , Kozma Erika , Furstoss Roland , Alphand Véronique 
Published: August 2007

AbstractCells of Escherichia coli expressing cyclohexanone monooxygenase catalyzed a highly enantioselective Baeyer–Villiger oxidation of α‐substituted cyanocyclohexanones, leading to the corresponding enantiopure caprolactones (ees >97 %). Classical kinetic resolution and regiodivergent parallel kinetic resolution patterns were observed, depending on the length of the linear chain at the alpha position. Regioselectivity was compared with that of chemical BV oxidations. Cells revealed an outstanding stability since 50 % of the specific BV activity was retained after 42 days of storage, which facilitates their use in biotransformations.
Chiral Amine Thiourea‐Promoted Enantioselective Domino Michael‐Aldol Reactions between 2‐Mercaptobenzaldehydes and Maleimides
Authors: Zu Liansuo , Xie Hexin , Li Hao , Wang Jian , Jiang Wei , Wang Wei 
Published: August 2007

AbstractAn organocatalytic, enantioselective domino Michael‐aldol reaction of 2‐mercaptobenzaldehydes with maleimides has been developed. The process, catalyzed by a bifunctional chiral amine thiourea via a hydrogen‐bonding mediated activation mechanism using as low as 1 mol % catalyst loading, affords versatile succinimide‐containing benzothiopyrans with the generation of 3 stereogenic centers in one single operation.
Tandem Metal‐ and Organocatalysis in Sequential Hydroformylation and Enantioselective Aldol Reactions
Authors: Chercheja Serghei , Eilbracht Peter 
Published: August 2007

AbstractMetal‐catalysed hydroformylation is successfully combined with organocatalysed stereoselective aldol addition into a tandem reaction sequence. This novel type of “tandem catalysis” allows access to complex molecular systems with high levels of enantioselectivity, using simple starting materials and an amino acid as the chiral catalyst.
Domino Hydroformylation/Enantioselective Cross‐Aldol Addition
Authors: Abillard Olivier , Breit Bernhard 
Published: August 2007

AbstractA domino hydroformylation/enantioselective cross‐aldol reaction sequence is reported. Starting from simple alkenes enantiomerically pure aldol addition products, which represent valuable building blocks for polypropionate construction, can be obtained in a one‐pot operation.
Efficient Acid‐Catalyzed Hydrolysis of Cellulose in Ionic Liquid
Authors: Li Changzhi , Zhao Zongbao K. 
Published: August 2007

AbstractA novel method for cellulose hydrolysis catalyzed by mineral acids in the ionic liquid 1‐butyl‐3‐methylimidazolium chloride ([C4mim]Cl) has been developed that facilitates the hydrolysis of cellulose with dramatically accelerated reaction rates at 100 °C under atmospheric pressure and without pretreatment.
Temperature‐induced morphology control in the polymer‐foaming process
Authors: Jacobs L. J. M. , Kemmere M. F. , Keurentjes J. T. F. , Mantelis Ch. A. , Meyer Th. 
Published: August 2007

AbstractSupercritical carbon dioxide (scCO2) is a promising foaming agent for the production of polymeric foams, representing an environmentally friendly alternative for the foaming agents currently used. During the expansion phase of the scCO2‐foaming process, temperature plays an essential role. This study focuses on relating the effects of temperature and pressure profiles on the foaming process and the resulting foam morphology. Therefore, several experiments have been performed in a high pressure reaction calorimeter (RC1e) that can be set to three different modes: isothermal, adiabatic, and isoperibolic. It has been observed that the foaming could be divided into four stages: nucleation, slow cell growth, fast cell growth, and shrinkage. The degree of shrinking that occurs is for a great deal dependent on the exposure to higher temperatures at the end of the foaming process. Since shrinkage does not occur in the adiabatic mode, this mode gives the best control on the foam morphology. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Mutations and polymorphisms in hemoglobin genes and the risk of pulmonary hypertension and death in sickle cell disease
Authors: Taylor James G. , Ackah Diana , Cobb Crystal , Orr Nick , Percy Melanie J. , Sachdev Vandana , Machado Roberto , Castro Oswaldo , Kato Gregory J. , Chanock Stephen J. , Gladwin Mark T. 
Published: August 2007

AbstractPulmonary hypertension is a common complication of sickle cell disease (SCD) and a risk factor for early death. Hemolysis may participate in its pathogenesis by limiting nitric oxide (NO) bioavailability and producing vasculopathy. We hypothesized that hemoglobin mutations that diminish hemolysis in SCD would influence pulmonary hypertension susceptibility. Surprisingly, coincident α‐thalassemia (Odds Ratio [OR] = 0.95, 95% CI = 0.46–1.94, P = NS) was not associated with pulmonary hypertension susceptibility in homozygous SCD. However, pulmonary hypertension cases were less likely to have hemoglobin SC (OR = 0.18, 95% confidence interval [CI] = 0.06–0.51, P = 0.0005) or Sβ+ thalassemia (OR = 0.25, 95% CI = 0.06–1.16, P = 0.10). These compound heterozygotes may be protected from pulmonary hypertension because of reduced levels of intravascular hemolysis, but develop this complication at a lower rate possibly due to the presence of non‐hemolytic risk factors such as renal dysfunction, iron overload and advancing age. Despite this protective association, patients with SC who did develop pulmonary hypertension remained at significant risk for death during 49 months of follow‐up (Hazard Ratio = 8.20, P = 0.0057). Am. J. Hematol., 2008. Published 2007 Wiley‐Liss, Inc.
UGT2B7 promoter variant −840G>A contributes to the variability in hepatic clearance of morphine in patients with sickle cell disease
Authors: Darbari Deepika S. , van Schaik Ron H.N. , Capparelli Edmund V. , Rana Sohail , McCarter Robert , van den Anker John 
Published: August 2007

AbstractThe purpose of the study was to determine if UDP‐glucuronosyltransferase (UGT) 2B7 allelic variants encoding for UGT2B7, primary enzyme responsible for morphine glucuronidation contribute to the variability in the hepatic clearance of morphine in sickle cell disease (SCD). Twenty‐four hour PK study of morphine and UGT2B7 variants genotyping was performed in 20 SCD patients in a steady state of health. Presence of the −840G allele (GG and GA) was associated with lower morphine metabolites/morphine AUC ratio compared with AA genotype (1.8 ± 0.5 vs. 3.0 ± 1.8 for M6G/M and 10.1 ± 2.7 vs. 15.7 ± 9.4 for M3G/M) (P = 0.03). Presence of UGT2B7 −840G allele is associated with significantly reduced glucuronidation of morphine and thus contributes to the variability in hepatic clearance of morphine in SCD. Am. J. Hematol., 2008. © 2007 Wiley‐Liss, Inc.