bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uneven distribution of nucleoside transporters and intracellular enzymatic degradation prevent transport of intact [14C] adenosine across the sheep choroid plexus epithelium as a monolayer in primary culture
Authors: Redzic Zoran B , Isakovic Aleksandra J , Misirlic Dencic Sonja T , Popadic Dusan , Segal Malcolm B 
Published: April 2006

Abstract

Background
Efflux transport of adenosine across the choroid plexus (CP) epithelium might contribute to the homeostasis of this neuromodulator in the extracellular fluids of the brain. The aim of this study was to explore adenosine transport across sheep CP epithelial cell monolayers in primary culture.

Methods
To explore transport of adenosine across the CP epithelium, we have developed a method for primary culture of the sheep choroid plexus epithelial cells (CPEC) on plastic permeable supports and analysed [14C] adenosine transport across this cellular layer, [14C] adenosine metabolism inside the cells, and cellular uptake of [14C] adenosine from either of the chambers. The primary cell culture consisted of an enriched epithelial cell fraction from the sheep fourth ventricle CP and was grown on laminin-precoated filter inserts.

Results and conclusion
CPEC grew as monolayers forming typical polygonal islands, reaching optical confluence on the third day after the seeding. Transepithelial electrical resistance increased over the time after seeding up to 85 ± 9 Ω cm2 at day 8, while permeability towards [14C] sucrose, a marker of paracellular diffusion, simultaneously decreased. These cells expressed some features typical of the CPEC in situ, including three nucleoside transporters at the transcript level that normally mediate adenosine transport across cellular membranes. The estimated permeability of these monolayers towards [14C] adenosine was low and the same order of magnitude as for the markers of paracellular diffusion.
However, inhibition of the intracellular enzymes, adenosine kinase and adenosine deaminase, led to a significant increase in transcellular permeability, indicating that intracellular phosphorylation into nucleotides might be a reason for the low transcellular permeability. HPLC analysis with simultaneous detection of radioactivity revealed that [14C] radioactivity which appeared in the acceptor chamber after the incubation of CPEC monolayers with [14C] adenosine in the donor chamber was mostly present as [14C] hypoxanthine, a product of adenosine metabolic degradation. Therefore, it appears that CPEC in primary cultures act as an enzymatic barrier towards adenosine. Cellular uptake studies revealed that concentrative uptake of [14C] adenosine was confined only to the side of these cells facing the upper or apical chamber, indicating uneven distribution of nucleoside transporters.
Oral mucosal melanoma: a malignant trap
Authors: Symvoulakis Emmanouil K , Kyrmizakis Dionysios E , Drivas Emmanouil I , Koutsopoulos Anastassios V , Malandrakis Stylianos G , Skoulakis Charalambos E , Bizakis John G 
Published: April 2006

Abstract
Oral mucosal melanomas are highly malignant tumors. The 'chameleonic' presentation of a mainly asymptomatic condition, the rarity of these lesions, the poor prognosis and the necessity of a highly specialized treatment are factors that should be seriously considered by the involved health provider. We present the case of a 75-year-old man who was referred to the Ear, Nose and Throat department. His symptoms were voice alteration and saliva drooling, progressively worsening during the last few weeks. The absence of pain was the reason for the delay of seeking medical care. The diagnosis was an oversized oral melanoma. This is an example of how the time of diagnosis and the evolution of a disease could be seriously influenced by patient's behavior. Melanomas arising from oral mucosa have poor prognosis unless they are discovered and treated early. The vigilance of the physicians is necessary to have success in this difficult task.
Conventional radiography requires a MRI-estimated bone volume loss of 20% to 30% to allow certain detection of bone erosions in rheumatoid arthritis metacarpophalangeal joints
Authors: Ejbjerg Bo Jannik , Vestergaard Aage , Jacobsen Søren , Thomsen Henrik , Østergaard Mikkel 
Published: April 2006

AbstractThe aim of this study was to demonstrate the ability of conventional radiography to detect bone erosions of different sizes in metacarpophalangeal (MCP) joints of rheumatoid arthritis (RA) patients using magnetic resonance imaging (MRI) as the standard reference. A 0.2 T Esaote dedicated extremity MRI unit was used to obtain axial and coronal T1-weighted gradient echo images of the dominant 2nd to 5th MCP joints of 69 RA patients. MR images were obtained and evaluated for bone erosions according to the OMERACT recommendations. Conventional radiographs of the 2nd to 5th MCP joints were obtained in posterior-anterior projection and evaluated for bone erosions. The MRI and radiography readers were blinded to each other's assessments. Grade 1 MRI erosions (1% to 10% of bone volume eroded) were detected by radiography in 20%, 4%, 7% and 13% in the 2nd, 3rd, 4th and 5th MCP joint, respectively. Corresponding results for grade 2 erosions (11% to 20% of bone volume eroded) were 42%, 10%, 60% and 24%, and for grade 3 erosions (21% to 30% of bone volume eroded) 75%, 67%, 75% and 100%. All grade 4 (and above) erosions were detected on radiographs. Conventional radiography required a MRI-estimated bone erosion volume of 20% to 30% to allow a certain detection, indicating that MRI is a better method for detection and grading of minor erosive changes in RA MCP joints.
Phylogenetic and structural analysis of centromeric DNA and kinetochore proteins
Authors: Meraldi Patrick , McAinsh Andrew D , Rheinbay Esther , Sorger Peter K 
Published: April 2006

Abstract
Background
Kinetochores are large multi-protein structures that assemble on centromeric DNA (CEN DNA) and mediate the binding of chromosomes to microtubules. Comprising 125 base-pairs of CEN DNA and 70 or more protein components, Saccharomyces cerevisiae kinetochores are among the best understood. In contrast, most fungal, plant and animal cells assemble kinetochores on CENs that are longer and more complex, raising the question of whether kinetochore architecture has been conserved through evolution, despite considerable divergence in CEN sequence.

Results
Using computational approaches, ranging from sequence similarity searches to hidden Markov model-based modeling, we show that organisms with CENs resembling those in S. cerevisiae (point CENs) are very closely related and that all contain a set of 11 kinetochore proteins not found in organisms with complex CENs. Conversely, organisms with complex CENs (regional CENs) contain proteins seemingly absent from point-CEN organisms. However, at least three quarters of known kinetochore proteins are present in all fungi regardless of CEN organization. At least six of these proteins have previously unidentified human orthologs. When fungi and metazoa are compared, almost all have kinetochores constructed around Spc105 and three conserved multi-protein linker complexes (MIND, COMA, and the NDC80 complex).

Conclusion
Our data suggest that critical structural features of kinetochores have been well conserved from yeast to man. Surprisingly, phylogenetic analysis reveals that human kinetochore proteins are as similar in sequence to their yeast counterparts as to presumptive Drosophila melanogaster or Caenorhabditis elegans orthologs. This finding is consistent with evidence that kinetochore proteins have evolved very rapidly relative to components of other complex cellular structures.
Chemical Shifts in ESCA and NMR: The Case of Bridged Trichlorosilyl-Trimethylsilyl Molecules
Authors: Nagaoka Shin-ichi , Nagashima Umpei , Ohshita Joji 
Published: April 2006

Abstract
A detailed examination of the relationship between chemical shifts in ESCA (electron spectroscopy for chemical analysis) and NMR (nuclear magnetic resonance) is presented for two silicon sites of bridged trichlorosilyl-trimethylsilyl molecules [Cl3Si–CnHm–Si(CH3)3 (n = 0–5 and m = 0–10)]. It is shown that the ESCA chemical shift of a silicon site mainly depends on the electronic environment within a mean radius of 1.168 Å of the nucleus and the NMR chemical shift depends on the electronic environment within a radius of more than 1.875 Å.
Electrochemical Investigations of Biologically Active 1-(3-Hydroxy-2-pyridyl)-4,4,6-trimethyl-3,4-dihydropyrimidine-2[1H]-thione at Pyrolytic Graphite Electrode
Authors: Goyal Rajendra N , Sondhi Sham M , Lahoti Anand M 
Published: April 2006

Abstract
Electrochemical behavior of a biologically active pyridinylpyrimidine derivative, 1-(3-hydroxy-2-pyridyl)-4,4,6-trimethyl-3,4-dihydropyrimidine-2[1H]-thione (1) has been investigated in aqueous phosphate buffers (1.9–10.6) at a pyrolytic graphite electrode (PGE). The oxidation occurred in a single well-defined oxidation peak, Ia, in the pH range 1.9–10.6. In the pH range 4.9–10.6, a reduction peak, IIc, was noticed in the reverse sweep that formed a quasi-reversible couple with peak IIa observed in the subsequent sweep towards positive potentials. The effect of concentration and sweep rate on peak potential and peak current of peak Ia established adsorption of 1 at the surface of PGE. Controlled potential coulometry experiments revealed the 5e− oxidation of 1 in acidic solution and 7e− oxidation in a neutral solution by an EC mechanism. UV–vis spectral and kinetic studies suggested formation of different intermediates in acidic and neutral media. The major product of oxidation at pH 2.7 was characterized as 2,2,4-trimethyl-2H-9-oxa-10-thia-1,4a,5-triazaphenanthrene 10,10-dioxide (6). At physiological pH 7.1, 1-(2,5-dioxo-6-pyridyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol (7a) and 1-(3,6-dioxo-3,6-dihydro-2-pyridyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-sulfonic acid (10) were identified as the oxidation products by GC-MS. A mechanism for the electrooxidation of 1 at PGE has also been suggested.
Synthesis of a Tetracopper Assembly Complex Comprised of One Macrocyclic Dinuclear Copper Unit and Two Mononuclear Copper Units: Intramolecular Electron Transfer Relevant to Multicopper Oxidase
Authors: Suetsugu Yuko , Mitsuka Yuko , Miyasato Yuji , Ohba Masaaki , Okawa Hisashi 
Published: April 2006

Abstract
The dinuclear copper(II) complex [Cu2(L1)](ClO4)2·CH3OH·2H2O (1) of a macrocyclic ligand H2L1, derived from the cyclic [2:2] condensation of 2,6-diformyl-4-methylphenol and 1,1,1-tri(aminomethyl)ethane, has been prepared as the type 3 copper site for modeling multicopper oxidase: 1 has two auxiliary amino groups on the macrocyclic framework. The condensation of 1 with two molecules of 2-formylpyridine through the amino groups afforded [Cu2(L2)](ClO4)2·2DMF (2). This has a Cu···Cu separation of 4.434(1) Å with no direct bridge between the two copper atoms, owing to the involvement of the auxiliary 2-pyridylmethylimino residue in coordination. The condensation of 1 with two molecules of 3-[N,N-di(2-pyridylmethyl)aminomethyl]-5-methylsalicylaldehyde in the presence of Cu(ClO4)2·6H2O afforded the tetracopper assembly complex [Cu4(L3)](ClO4)4·3H2O (3), which is comprised of a macrocyclic dinuclear Cu2(II,II) unit and two mononuclear Cu(II) units, {Cu(II)–Cu2(II,II)–Cu(II)}. Cyclic voltammograms of 3 exhibit a two-electron redox process at −0.77 V (vs Ag/Ag+) followed by two one-electron redox processes at −0.85 and −1.29 V. Coulometric studies combined with spectroscopic and EPR studies demonstrate that the redox process at −0.77 V involves the reduction of two mononuclear Cu(II) units followed by an intramolecular electron transfer from one of the reduced Cu(I) units to the dinuclear Cu2(II,II) unit: {Cu(II)–Cu2(II,II)–Cu(II)}/{Cu(I)–Cu2(II,II)–Cu(I)} → {Cu(I)–Cu2(I,II)–Cu(II)}. The resulting {Cu(I)–Cu2(I,II)–Cu(II)} species is further reduced to {Cu(I)–Cu2(I,II)–Cu(I)} at −0.85 V and to {Cu(I)–Cu2(I,I)–Cu(I)} at −1.29 V.
Dehydrogenative Nucleophilic Addition of Aliphatic Ether to Benzaldehyde Dimethyl Acetal Mediated by Ether–Boron Trifluoride (1/1) Affording 1-Alkoxy-2-alkylindenes or α,β-Unsaturated Carbonyl Compounds Specifically
Authors: Jobashi Takashi , Maeyama Katsuya , Noguchi Keiichi , Yoshida Yasuhiko , Yonezawa Noriyuki 
Published: April 2006

Abstract
The R2O·BF3-mediated dehydrogenative crossed aldol condensation reaction of acyclic aliphatic ethers with benzaldehyde dimethyl acetal to give specifically indene derivatives or α,β-unsaturated carbonyl compounds has been found. When the ethers have bis(β-alkylethyl) ether structures, dehydrogenative formation of enol ether equivalents followed by successive crossed aldol addition to acetal-originated electrophile and intramolecular electrophilic aromatic substitution reactions give annulation products of 1-alkoxy-2-alkylindenes. When the ether has two β- and one or more α-hydrogens, α,β-unsaturated carbonyl compounds are obtained. The structural correlation between deuterated starting materials and the obtained products, the structural requirements for ethers, and the distinct substrate specificity have revealed the reaction routes and mechanisms.
Characterization of RNA in Saliva
Authors: Park Noh Jin , Li Yang , Yu Tianwei , Brinkman Brigitta MN , Wong David T 
Published: April 2006

AbstractBackground: We have previously shown that human mRNAs are present in saliva and can be used as biomarkers of oral cancer. In this study, we analyzed the integrity, sources, and stability of salivary RNA.Methods: We measured the integrity of salivary RNA with reverse transcription followed by PCR (RT-PCR) or RT-quantitative PCR (RT-qPCR). To study RNA entry sites into the oral cavity, we used RT-PCR analysis of salivary RNA from the 3 major salivary glands, gingival crevice fluid, and desquamated oral epithelial cells. We measured stability of the salivary β-actin mRNA by RT-qPCR of salivary RNA incubated at room temperature for different periods of time. We measured RNA association with other macromolecules by filtering saliva through pores of different sizes before performing RT-qPCR. To assess RNA–macromolecule interaction, we incubated saliva with Triton X-100 for different periods of time before performing RT-qPCR.Results: In most cases, we detected partial- to full-length salivary mRNAs and smaller amounts of middle and 3′ gene amplicons compared with the 5′. RNA was present in all oral fluids examined. Endogenous salivary β-actin mRNA degraded more slowly than exogenous β-actin mRNA, with half-lives of 12.2 and 0.4 min, respectively (P &lt;0.001). Salivary RNA could not pass through 0.22 or 0.45 μm pores. Incubation of saliva with Triton X-100 accelerated degradation of salivary RNA.Conclusions: Saliva harbors both full-length and partially degraded forms of mRNA. RNA enters the oral cavity from different sources, and association with macromolecules may protect salivary RNA from degradation.
Drug screening in urine by cloned enzyme donor immunoassay (CEDIA) and kinetic interaction of microparticles in solution (KIMS): a comparative study
Authors: Schwettmann Lutz , Külpmann Wolf-Rüdiger , Vidal Christian 
Published: April 2006

AbstractTwo commercially available drug-screening assays were evaluated: the Roche kinetic interaction of microparticles in solution (KIMS) assay and the Microgenics cloned enzyme donor immunoassay (CEDIA). Urine samples from known drug-abuse patients were analyzed for amphetamines, barbiturates, benzodiazepines, benzoylecgonine, cannabinoids, LSD, methadone and opiates. Samples with discordant findings for the two assays were analyzed by gas chromatography/mass spectrometry (GC/MS) or gas chromatography/electron capture detection (GC/ECD). Amphetamines showed 96.0% concordant results, with two false positive findings by CEDIA, three by KIMS and a further two false negatives by KIMS. Barbiturates showed 99.4% concordant results, with one false negative by KIMS. Benzodiazepines showed 97.4% concordant results, with two false negatives by KIMS (cutoff 100μg/L, CEDIA cutoff 300 μg/L). Benzoylecgonine showed 17.8% concordant positive and 82.2% concordant negative results and no false finding by either assay. Cannabinoids showed 99.3% concordant results, with one sample negative by KIMS at a cutoff of 50μg/L and positive by CEDIA (cutoff 25μg/L). For LSD, 6.7% of findings were not in agreement. Methadone showed 97.5% concordant results, with two false positives by CEDIA, and one false positive and one false negative by KIMS. Opiates showed 96.9% concordant results, with no false KIMS results, but four false positives by CEDIA. The results indicate that the agreement of the CEDIA and KIMS results for the eight drugs is rather good (93.3–100%).
Effects of Photodegradation on the Physical and Antioxidant Properties of Melanosomes Isolated from Retinal Pigment Epithelium
Authors: Zareba Mariusz , Szewczyk Grzegorz , Sarna Tadeusz , Hong Lian , Simon John D. , Henry Michele M. , Burke Janice M. 
Published: April 2006

ABSTRACTMelanosomes of the retinal pigment epithelium (RPE) are relatively long‐lived organelles that are theoretically susceptible to changes induced by exposure to visible light. Here melanosomes were isolated from porcine RPE cells and subjected to high intensity visible light to determine the effects of illumination on melanosome structure and on the content and antioxidant properties of melanin. As compared to untreated melanosomes, illuminated granules showed morphologic changes consistent with photodegradation, which included variable reductions in electron density demonstrated by transmission electron microscopy (TEM), and particle fragmentation and surface disruption revealed by scanning electron microscopy (SEM) and atomic force microscopy. Illuminated melanosomes had lower melanin content, indicated by measures of absorbance and electron spin resonance (ESR) signal intensity, and reduced ability to bind iron, shown by chemical and ESR analyses. Compared to untreated melanosomes, ESR‐spin trapping analyses further indicated that illuminated melanosomes show increased photogeneration of superoxide anion and reduced ability to inhibit the iron ion‐catalyzed free radical decomposition of hydrogen peroxide. It appears therefore that visible light irradiation can disrupt the structure of RPE melanosomes and reduce the amount and antioxidant properties of melanin. Some of these changes occur in human RPE melanosomes with aging and the results obtained here suggest that visible light irradiation is at least partly responsible. The consequence of light‐induced changes in RPE melanosomes may be a diminished capacity of melanin to help protect aged cells from oxidative damage, perhaps increasing the risk of diseases with an oxidative stress component such as age‐related macular degeneration.
Use of Mini Implants for Replacement and Immediate Loading of 2 Single-tooth Restorations: A Clinical Case Report
Authors: Siddiqui Azfar A. , Mark Sosovicka, , Mark Goetz, 
Published: April 2006

Abstract
Numerous long-term studies have shown that treatment with dental implants can provide edentulous patients with a more stable alternative to complete dentures and partially edentulous patients with a more conservative form of tooth replacement than conventional fixed partial dentures. Until recently, commercially available dental implants have been limited to diameters ranging from 3.0 mm to 7.0 mm. Although this range of diameters has been able to address most clinical needs, partially edentulous patients who could not accommodate a 3.0-mm-diameter implant without damaging adjacent dental structures were excluded from implant therapy. This article reports on the surgical treatment and immediate restoration of a patient who received mini implants that were 2.4 mm in diameter.
Plant-Based Diets and Risk of Hip Fracture in Postmenopausal Women
Authors: Sotos-Prieto Mercedes , Rodriguez-Artalejo Fernando , Fung Teresa T. , Meyer Haakon E. , Hu Frank B. , Willett Walter C. , Bhupathiraju Shilpa N. 
Published: February 2024

ImportancePrevious research has found that vegetarian diets are associated with lower bone mineral density and higher risk of fractures, but these studies did not differentiate the quality of the plant-based foods.ObjectiveTo examine the association between the quality of plant-based diets (not necessarily vegan but also omnivorous) and hip fracture risk among postmenopausal women in the Nurses’ Health Study.Design, Setting, and ParticipantsThis cohort study analyzed data from 70 285 postmenopausal women who participated in the US Nurses’ Health Study from 1984 through 2014. Data were analyzed from January 1 to July 31, 2023.Main outcomes and MeasuresHip fractures were self-reported on biennial questionnaires. Diet was assessed every 4 years using a validated semiquantitative food frequency questionnaire. Plant-based diet quality was assessed using 2 previously established indices: the healthful Plant-Based Diet Index (hPDI), for which healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, vegetable oils, and tea or coffee) received positive scores, whereas less healthy plant foods (fruit juices, sweetened beverages, refined grains, potatoes, and sweets or desserts) and animal foods received reversed scores; and the unhealthful Plant-Based Diet Index (uPDI), for which positive scores were given to less healthy plant foods and reversed scores to healthy plant and animal foods. Quintile scores of 18 food groups were summed, with a theoretical range for both indices of 18 to 90 (highest adherence). Cox proportional hazards regression with time-varying covariates was used to compute hazard ratios (HRs) and 95% CIs for hip fracture.ResultsIn total, 70 285 participants (mean [SD] age, 54.92 [4.48] years; 100% White women) were included, and 2038 cases of hip fracture were ascertained during the study and for up to 30 years of follow-up. Neither the hPDI (HR for highest vs lowest quintile, 0.97 [95% CI, 0.83-1.14]) nor the uPDI (HR for highest vs lowest quintile, 1.02 [95% CI, 0.87-1.20]) for long-term diet adherence was associated with hip fracture risk. However, when examining recent intake for the highest vs lowest quintiles, the hPDI was associated with 21% lower risk of hip fracture (HR, 0.79 [95% CI, 0.68-0.92]; P = .02 for trend), and the uPDI was associated with 28% higher risk (1.28 [95% CI, 1.09-1.51]; P = .008 for trend).Conclusions and RelevanceFindings of this cohort study indicated that long-term adherence to healthful or unhealthful plant-based diets as assessed by hPDI and uPDI scores was not associated with hip fracture risk. Future research should clarify whether the associations observed with recent dietary intake are due to short-term effects of these dietary patterns, reverse causality, or both.