bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of signal‐to‐noise ratio and spectral linewidth on metabolite quantification at 4 T
Authors: Bartha Robert 
Published: January 2007

AbstractThe accuracy and precision of measurements of metabolite concentrations from short echo‐time spectra has previously been characterized at l.5 T as a function of signal‐to‐noise ratio (SNR) and peak linewidth. The purpose of this study was to characterize the systematic error in quantification of metabolite concentrations associated with linewidth and SNR for the major metabolites of interest in the short echo‐time 1H‐MR spectrum at 4 T. Simulated 4 T LASER localized spectra (TE = 46 ms) were generated with full width at half maximum (FWHM) over the range 4–14 Hz, and SNR over the range 5–500 by adding 100 Gaussian‐distributed noise realizations at each combination of SNR and linewidth. Linewidth and SNR were treated as independent parameters, and therefore an increase in linewidth at a constant SNR resulted in increased metabolite areas. All spectra were fitted in the time domain using identical prior‐knowledge and relative parameter starting values. Six metabolites (N‐acetylaspartate, glutamate, creatine, myo‐inositol, glycerophosphocholine, phosphocholine) were quantified with >90% accuracy and <10% standard deviation at SNR = 10 for linewidths ranging from 8 to 14 Hz FWHM. These simulations did not consider additional sources of variation, including eddy current artifacts, incomplete macromolecule baseline removal, and incomplete water suppression. Regardless, the results show that metabolite quantification from 4 T short echo‐time 1H‐MRS is sensitive to SNR and linewidth. Copyright © 2007 John Wiley & Sons, Ltd.
Modeling the octanol–water partition coefficient of substituted phenols by the use of structure information
Authors: Jäntschi Lorentz , Bolboacă Sorana‐Daniela 
Published: January 2007

AbstractThis work presents the abilities in estimation and prediction of the octanol–water partition coefficient of some para‐substituted phenols through the integration of complex structures information by the use of an original molecular descriptors family on the structure–property relationship approach. The proposed approach uses the complex information obtained from para‐substituted phenols structure in order to generate and calculate the molecular descriptors family. The structure–property relationship models were built based on the generated descriptors. The obtained multi‐varied models (model with two and four descriptors, respectively) were validated through the assessment of the cross‐validation leave‐one‐out score. The comparison between the multi‐varied model with two and four descriptors was performed using Steiger's Z‐test. The analysis of the statistical characteristics of the obtained models demonstrated that the model with four descriptors has greater ability to estimate and predict compared with the model with two descriptors. This observation was also sustained by the results of correlated‐correlation analysis. The multi‐varied model with four descriptors revealed that the octanol‐water partition coefficient of studied para‐substituted phenols is likely to be of geometry nature, it is strongly dependent on the partial charges of compounds and group electronegativity, and it is in relation to the elastic force. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Effects of octylglucoside and triton X‐100 on the kinetics and specificity of carnitine palmitoyltransferase
Authors: Fiol Carol J. , Bieber Loran L. 
Published: January 2007

AbstractThe effects of octylglucoside on the substrate specificity, kinetics and aggregation state of purified carnitine palmitoyltrasferase (CPT) from beef heart mitochondria were investigated and compared to the effects of Triton X‐100. Conditions in which CPT can be assayed in the absence of micelles and albumin, thereby eliminating miceller effects on the kinetic parameters, are described. When octylglucoside is substituted for Triton X‐100, the specificity of CPT in the forward direction shifts towards the long‐chain acyl‐CoAs, and large changes in the kinetic constants are observed. The K0.5 for L‐carnitine varied as much as 50‐fold, depending on the acyl‐CoA and detergent used. At pH 8.0 and 200 μM palmitoyl‐CoA, the K0.5 for L‐carnitine is 4.9 mM in 12 mM octylglucoside and 0.2 mM in 0.1% Triton X‐100. Octylglucoside enhances the activity of CPT with long‐chain acyl‐CoA and lowers the K0.5 for these substrates. At pH 6.0, the K0.5 for palmitoyl‐CoA is 24.2 μM in 0.1% Triton X‐100, in contrast to 3.1 μM in 12 mM octylglucoside. Octylglucoside is a competitive inhibitor of CPT with octanoyl‐CoA as substrate with a Ki of 15 mM. Nonlinear kinetics for both acyl‐CoAs and L‐carnitine are observed when the concentration of octylglucoside is reduced to less than half of its critical micellar concentration (cmc). Gel filtration of CPT in octylglucoside below its cmc gives a single protein peak with a molecular mass of ca. 660,000 daltons. These data indicate that the catalytically active form of purified CPT is an aggregate that has quaternary structure and must have a very flexible catalytic site whose affinity for substrate and catalytic efficiency can be altered greatly by changes in environment and experimental conditions.
Effect of choline, ethanolamine and serine supplementation on the membrane properties ofMicrosporum gypseum
Authors: Pandey R. , Verma R. S. , Khuller G. K. 
Published: January 2007

AbstractPhospholipid bases, choline and ethanolamine, when supplemented in the growth medium ofMicrosporum gypseum resulted in an increase in the corresponding phospholipid and total phospholipid content. However, when serine was supplemented, marginal changes were observed. The fatty acid profile of phospholipids remained almost unchanged. The uptake of lysine, leucine and aspartic acid in the spheroplasts of choline‐ and ethanolamine‐grown cells was higher as compared to the control. 1‐Anilinonaphathalene‐8‐sulfonate (ANS) binding to the spheroplast membrane, as calculated from Scatchard plots, demonstrated an increase in the number of binding sites in choline‐ and ethanolamine‐grown cells, while a decrease was observed in the serine‐supplemented cells. The results are discussed in terms of the effect of phospholipid polar head group composition on the membrane structure and function of this fungus.
Lack of regression of preestablished gallstones in mice
Authors: Beynen Anton C. 
Published: January 2007

AbstractFeeding a high cholesterol, high cholic acid diet to mice for 28 days caused increased concentrations of plasma and liver cholesterol and formation of gallstones. Removal of cholesterol and cholic acid from the diet led to normalization of plasma and liver cholesterol within 28 days. Regression of the preestablished gallstones did not occur within 107 days.
Fatty acid biosynthesis during embryogenesis in the amphibianBufo arenarum Hensel
Authors: Miceli Dora C. , Brenner Rodolfo R. 
Published: January 2007

AbstractThe fatty acid composition and biosynthesis of fatty acids were studied during early embryogenesis of the toadBufo arenarum Hensel. The ova and stages up to the 6 1/2 day embryo have similar fatty acid compositions, with ca. 70% unsaturated acids. The eggs and embryo were permeable to acetate and impermeable to palmitic, linoleic, and eicosa‐8,11,14‐trienoic acid. Labeled acetate was incorporated by the eggs into the saturated acids‐lauric, myristic, palmitic, stearic, arachidic, and behenic‐and into the unsaturated acids‐myristoleic, palmitoleic, oleic, and eicosaenoic acids. During segmentation and gastrulation, de novo biosynthesis of fatty acids increased, desaturation to myristoleic, palmitoleic, and oleic acids was enhanced; and fatty acids were esterified to triglycerides, phosphatidyl choline, and phosphatidyl ethanolamine. The feeding embryo (11 days) changed the pattern of incorporation to less incorporation into triglycerides.
Effect of vitamin E deficiency on the lipid class and fatty acid composition of rat brain gray and white matter
Authors: Vatassery G. T. , Berry J. F. , Younozai R. , Bergad P. Lam 
Published: January 2007

AbstractThree‐week old male Sprague‐Dawley rats were placed on a control or vitamin E‐deficient diet for 9 months. The total lipid and cholesterol contents of brain gray and white matter areas in the vitamin E‐deficient group did not differ from controls. The concentration of cerebrosides was lower in white matter but higher in gray matter of deficient animals. However, sulfatide was significantly (P<0.001) higher in white and gray matter of deficient animals compared with controls. Lysolecithin was not found in vitamin E‐deficient gray matter but was present in control gray matter lipids. No marked differences were found in the concentrations or relative amounts of sphinogomyelin, phosphatidyl choline, phospholipids of gray or white matter of vitamin E‐deficient rats as compared to controls. In addition no remarkable differences were found in the fatty acid composition of total lipid extracts of gray or white matter from vitamin E‐deficient rats when compared with controls.
Albumin‐bound docosahexaenoic acid and collagen‐induced human platelet reactivity
Authors: Gaudette Douglas C. , Holub Bruce J. 
Published: January 2007

AbstractAnin vitro system designed to mimic the effect of various plasma nonesterified (polyunsaturated) fatty acids on platelet function and metabolism was employed. Human platelet aggregation induced by submaximal (1.8 μg/ml) collagen stimulation was significantly inhibited by 2 min preincubation with 20 μM albumin‐bound docosahexaenoic acid (22∶6n−3) (DHA), but not by the other fatty acids tested. [3H]Phosphatidic acid (PA) formation, an indicator of phospholipase C activation following platelet stimulation, was moderately inhibited by eicosapentaenoic acid (20∶5n−3), 11,14,17‐eicosatrienoic acid (20∶3n−3), dihomo‐γ‐linolenic acid (20∶3n−6), as well as DHA, but not by arachidonic acid (20∶4n−6); this inhibition of phospholipase C activation could not explain the differential effect of DHA on platelet aggregation. The decreased production of thromboxane A2 (TxA2), as assessed by [3H]12‐hydroxy‐5,8,10‐heptadecatrienoic acid (HHT) formation, may account for the inhibition of collagen‐induced aggregation by 20 μM DHA. Surprisingly, preincubation with 40 μM albumin‐bound DHA, even though resulting in greater inhibition of collagen‐induced aggregation, had less impact on HHT formation. A small but significant increase in [3H]prostaglandin D2 (PGD2) levels following 3‐min collagen stimulation may have contributed to the greater antiaggregatory effect of 40 μM DHA. It is concluded that increased plasma nonesterified DHA may contribute to the dampened platelet activation and altered metabolism following fish oil supplementation of the diet.
Discharge of newly‐synthesized dolichol and ubiquinone with lipoproteins to rat liver perfusate and to the bile
Authors: Elmberger P. Göran , Kalen Anders , Brunk Ulf T. , Dallner Gustav 
Published: January 2007

AbstractAn effective system for perfusing rat liver using complete tissue culture medium and washed calf erythrocytes as oxygen carriers was devised. Infusion of taurocholate and glucose proved necessary to maintain stable metabolic activity an bile secretion during a 6‐hr period. Perfusate pO2, pCO2 and pH values were monitored continuously and found to be stable. Electron microscopic examination revealed the maintenance of normal hepatic structure, even after 6 hr. Normal rates of protein and urea synthesis, no leakage of cytoplasmic enzymes, and continuous bile acid production demonstrated the functional integrity of this system. Using [3H]mevalonic acid as precursor, dolichol, dolichyl phosphate, ubiquinone and cholesterol were found to be continuously synthesized in this perfusate, indicating discharge through the ER‐Golgi system. The lipoproteins of the perfusate were isolated by ultracentrifugation and characterized with respect to size distribution and lipid composition. Dolichol was found in VLDL, LDL and HDL fractions, with the highest concentration present in the latter. In rat and human blood plasma this lipid was mainly associated with HDL. The ubiquinone in the perfusate was primarily associated with the VLDL fraction, while in rat plasma it was found more evenly distributed among all the three lipoprotein fractions studied. Dolichol, ubiquinone and cholesterol were also discharged to the bile, whereas dolichyl phosphate was not. Thus, newly‐synthesized dolichol and ubiquinone are transported out of the hepatocyte to the blood and to the bile.
Synthesis of trideuteratedO‐alkyl platelet activating factor and lyso derivatives
Authors: Prakash Chandra , Saleh Sam , Taber Douglass F. , Blair Ian A. 
Published: January 2007

AbstractRacemic heavy isotope analogs of 1‐O‐alkyl‐sn‐glycero‐3‐phosphocholine (lysoPAF) and 1‐O‐alkyl‐2‐O‐acetyl‐sn‐glycero‐3‐phosphocholine (PAF) were prepared for use as internal standards to facilitate quantitative studies based on mass spectrometry. Starting from pentadencane‐1,15‐diol andrac‐glycerol‐1,2‐acetonide, a convergent synthesis of 1‐O‐[16′‐2H3]hexadecyl and 1‐O‐[18′‐2H3]octadecylrac‐glycero‐3‐phosphocholine and their acetyl derivatives is described. Three deuterium atoms were introduced at the terminal position of the 1‐O‐alkyl group by displacement of thep‐toluensulfonyl group from 1‐O‐alkyl‐15′‐p‐toluensulfonate and 1‐O‐alkyl‐17′‐p‐toluensulfonate with [2H3]‐methylmagnesium iodide. The 1‐O‐alkyl‐17′‐p‐toluensulfonate was obtained by reaction of the 1‐O‐alkyl‐15′‐p‐toluensulfonate with allylmagnesium bromide, followed by reductive ozonolysis and treatment withp‐toluenesulfonyl chloride. The hydroxyl group at C‐2 was protected by a benzyl group and removed at a late stage in the synthesis. This provided the corresponding lysoderivatives or allowed preparation of racemic PAF by subsequent acetylation of the free hydroxy group. The phosphocholine moiety was introduced at glycerol C‐3 by reaction with bromoethyldichlorophosphate and trimethylamine. The synthetic compounds were analyzed by FAB/MS and GC/NICIMS. They were shown to contain less than 0.6% protium impurity.
Plasma lipoproteins in dairy cows with naturally occurring severe fatty liver: Evidence of alteration in the distribution of apo A‐I‐containing lipoproteins
Authors: Mazur Andrzej , Marcos Edgardo , Rayssiguier Yves 
Published: January 2007

AbstractThe relationships between fatty liver in dairy cows and reduced levels of plasma lipoproteins, and particularly of low density lipoproteins (LDL), has been previously described. Since electrophoretic heterogeneity of ultracentrifugally isolated LDL (d, 1.006–1.063 g/ml) has been found, the exact nature of this reduction in cows with fatty liver was investigated. Lipoproteins from control and severely afflicted animals were isolated by ultracentrifugation and affinity chromatography on heparin‐Sepharose CL 6 B. Gradient gel electrophoresis of lipoproteins on 4–30% gels and an immunolocalization study of apoprotein A‐I (apo A‐I) showed that control animals have two subpopulations of apo A‐I‐containing particles with a mean radius of 6.52 and 5.05 nm. In the fatty liver cows, the former was clearly shifted toward smaller particles. We concluded that the depressed level and compositional modifications of LDL in severe fatty liver cows result from a decrease in the oversized apo A‐I‐containing lipoproteins which can be isolated in the LDL density range. This could stem from the decreased supply of triglyceride‐rich lipoprotein surface components for the production of these lipoproteins. The modifications can be plausibly explained by a reduced synthesis or secretion of very low density lipoproteins (VLDL) by the liver.
Environmental changes in the northern Altai during the last millennium documented in Lake Teletskoye pollen record
Authors: Andreev Andrei A. , Pierau Roberto , Kalugin Ivan A. , Daryin Andrei V. , Smolyaninova Lyubov G. , Diekmann Bernhard 
Published: January 2007

AbstractA high-resolution pollen record from Lake Teletskoye documents the climate-related vegetation history of the northern Altai Mountain region during the last millennium. Siberian pine taiga with Scots pine, fir, spruce, and birch dominated the vegetation between ca. AD 1050 and 1100. The climate was similar to modern. In the beginning of the 12th century, birch and shrub alder increased. Lowered pollen concentrations and simultaneous peaks in herbs (especially Artemisia and Poaceae), ferns, and charcoal fragments point to colder and more arid climate conditions than before, with frequent fire events. Around AD 1200, regional climate became warmer and more humid than present, as revealed by an increase of Siberian pine and decreases of dry herb taxa and charcoal contents. Climatic conditions were rather stable until ca. AD 1410. An increase of Artemisia pollen may reflect slightly drier climate conditions between AD 1410 and 1560. Increases in Alnus, Betula, Artemisia, and Chenopodiaceae pollen and in charcoal particle contents may reflect further deterioration of climate conditions between AD 1560 and 1810, consistent with the Little Ice Age. After AD 1850 the vegetation gradually approached the modern one, in conjunction with ongoing climate warming.
Responses of the entomopathogenic nematode,Steinernema riobraveto its insect hosts,Galleria mellonellaandTenebrio molitor
Authors: CHRISTEN J. M. , CAMPBELL J. F. , LEWIS E. E. , SHAPIRO-ILAN D. I. , RAMASWAMY S. B. 
Published: January 2007

SUMMARYPotential hosts for infective juveniles of entomopathogenic nematodes can vary considerably in quality based on the characteristics of the host species/stage, physiological status (e.g. stress, feeding on toxins), and infection status (heterospecific or conspecific infection). In this study, we investigated responses of the entomopathogenic nematodeSteinernema riobraveto hosts (Galleria mellonellaorTenebrio molitor) that were previously parasitized with conspecifics or injected with the nematode-symbiotic bacterium,Xenorhabdussp., to determine if there is a preference for previously parasitized/injected hosts and when this preference might occur. In no-choice bioassays, the number of juveniles infecting both host species decreased with increasing time post-infection. However, infective juveniles continued to infect previously parasitized hosts up to 72 h. Significant preference was exhibited byS. riobravefor 24 h post-infectionG. mellonellalarvae over uninfected, and by 24 h post-injectionG.mellonellalarvae over 48 h post-injection larvae. No significant preference was exhibited byS. riobraveforT. molitorhosts previously parasitized with conspecifics or those injected with bacteria in any treatment combination. Such preference for, or continued infection of parasitized insects, has the potential to impact nematode efficacy.
Einstein and Oppenheimer: Interactions and Intersections
Authors: Schweber Silvan S. 
Published: January 2007

ArgumentThe paper is an exploration of the interactions between Einstein and Oppenheimer. It highlights the sharp differences in Einstein's and Oppenheimer's approach to physics, in their presentation of self as iconic figures, and in their relation to the communities they considered themselves part of. To understand their differing approaches to physics it briefly reviews the kinds of unifications that took place in physics during the first two-thirds of the twentieth century and points to the 1961 MIT centennial celebration to demonstrate the potency of Einstein's vision that there might be a fundamental theory from which all known theories could be derived. It also briefly reviews various aspects of the development of theoretical physics and of general relativity in the first two-thirds of the twentieth century, to better understand the context of the sharp, negative remarks that Oppenheimer made about Einstein and about his theory of general relativity in 1965 on the occasion of the tenth anniversary of Einstein's death. To answer the question: “Why the antagonism on Oppenheimer's part?” it looks at Oppenheimer's and Einstein's relation to their Jewish roots, their stance regarding nationalism, and their philosophical commitments.
Prevalence and Risk Factors for Bloodborne Exposure and Infection in Correctional Healthcare Workers
Authors: Gershon Robyn R. M. , Sherman Martin , Mitchell Clifford , Vlahov David , Erwin Melissa J. , Lears Mary Kathleen , Felknor Sarah , Lubelczyk Rebecca A. , Alter Miriam J. 
Published: January 2007

Objective.To determine the prevalence and risk factors for bloodborne exposure and infection in correctional healthcare workers (CHCWs).Design.Cross-sectional risk assessment study with a confidential questionnaire and serological testing performed during 1999-2000.Setting.Correctional systems in 3 states.Results.Among 310 participating CHCWs, the rate of percutaneous injury (PI) was 32 Pis per 100 person-years overall and 42 Pis per 100 person-years for CHCWs with clinical job duties. Underreporting was common, with only 25 (49%) of 51 Pis formally reported to the administration. Independent risk factors for experiencing PI included being age 45 or older (adjusted odds ratio [aOR], 2.41 (95% confidence interval (CI), 1.31-4.46]) and having job duties that involved needle contact (aOR, 3.70 [95% CI, 1.28-10.63]) or blood contact (aOR, 5.05 [95% CI, 1.45-17.54]). Overall, 222 CHCWs (72%) reported having received a primary hepatitis В vaccination series; of these, 150 (68%) tested positive for anti-hepatitis B surface antigen, with negative results significantly associated with receipt of last dose more than 5 years previously. Serologic markers of hepatitis В virus infection were identified in 31 individuals (10%), and the prevalence of hepatitis B virus infection was 2% (n = 7). The high hepatitis B vaccination rate limited the ability to identify risk factors for infection, but hepatitis C virus infection correlated with community risk factors only.Conclusion.Although the wide coverage with hepatitis B vaccination and the decreasing rate of hepatitis C virus infection in the general population are encouraging, the high rate of exposure in CHCWs and the lack of exposure documentation are concerns. Continued efforts to develop interventions to reduce exposures and encourage reporting should be implemented and evaluated in correctional healthcare settings. These interventions should address infection control barriers unique to the correctional setting.
Observations with the Electron Microscope on the Internal Structure of the Spermatozoid of Fucus
Authors: MANTON I. , CLARKE B. 
Published: January 2007

Abstract
After preliminary description of antheridial dehiscence, details have been given of the internal structure and position inside the body of the Fucus spermatozoid of the following organs: mitochondria, chromatophore and eyespot, ciliary bases, proboscis. The position and approximate shape of the nucleus both expanded and in the coiled condition are described. The body membrane and its relation to the covering membrane of the proboscis and two flagella are described. The plane of symmetry of both flagella relative to the surface of the body is described.
The more important individual facts recorded are:
1. The plane of symmetry in both flagella is at right angles to the body surface, passing between but not through the two central strands in each flagellum.
2. A group of dark bodies previously mistaken for the nucleus are mitochondria.
3. The proboscis is part of the ciliary apparatus; it is covered on each side by a membrane and the internal thickening bands are attached at one end to the basal body of the front flagellum.