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1.
Jpn Dent Sci Rev ; 60: 175-189, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38938474

ABSTRACT

This review examined the efficacy of surface treatments and adhesive monomers for enhancing zirconia-resin bond strength. A comprehensive literature search in PubMed, Embase, Web of Science, Scopus, and the Cochrane Library yielded relevant in vitro studies. Employing pairwise and Bayesian network meta-analyses, 77 articles meeting inclusion criteria were analyzed. Gas plasma was found to be ineffective, while treatments including air abrasion, silica coating, laser, selective infiltration etching, hot etching showed varied effectiveness. Air abrasion with finer particles (25-53 µm) showed higher immediate bond strength than larger particles (110-150 µm), with no significant difference post-aging. The Rocatec silica coating system outperformed the CoJet system in both immediate and long-term bond strength. Adhesives containing 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) were superior to other acidic monomers. The application of 2-hydroxyethyl methacrylate and silane did not improve bonding performance. Notably, 91.2 % of bonds weakened after aging, but this effect was less pronounced with air abrasion or silica coating. The findings highlight the effectiveness of air abrasion, silica coating, selective infiltration etching, hot etching, and laser treatment in improving bond strength, with 10-MDP in bonding agents enhancing zirconia bonding efficacy.

2.
Front Bioeng Biotechnol ; 11: 1309503, 2023.
Article in English | MEDLINE | ID: mdl-38169916

ABSTRACT

Objective: This paper aimed to assess the impact of the acetone wet-bonding (AWB) technique on dentin bonding and to investigate its potential underlying mechanisms. Materials and Methods: Caries-free third molars were sliced, ground, etched, water-rinsed. Then the specimens were randomly allocated to four groups according to the following pretreatments: 1. water wet-bonding (WWB); 2. ethanol wet-bonding (EWB); 3. 50% (v/v) acetone aqueous solution (50%AWB); 4. 100% acetone solution (AWB). Singlebond universal adhesive was then applied and composite buildups were constructed. The microtensile bond strength (MTBS), failure modes and interface nanoleakage were respectively evaluated after 24 h of water storage, 10,000 times of thermocycling or 1-month collagenase ageing. In situ zymography and contact angle were also investigated. Results: Acetone pretreatment preserved MTBS after thermocycling or collagenase ageing (p < 0.05) without affecting the immediate MTBS (p > 0.05). Furthermore, AWB group manifested fewer nanoleakage than WWB group. More importantly, the contact angle of the dentin surfaces decreased significantly and collagenolytic activities within the hybrid layer were suppressed in AWB group. Conclusion: This study suggested that the AWB technique was effective in enhancing the dentin bond durability by increasing the wettability of dentin surface to dental adhesives, removing residual water in the hybrid layer, improving the penetration of adhesive monomer, and inhibiting the collagenolytic activities. Clinical significance: The lifespan of adhesive restorations would be increased by utilization of acetone wet-bonding technique.

3.
China Tropical Medicine ; (12): 289-2023.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-979632

ABSTRACT

@#Abstract: Objective The purpose of this study is to find out the epidemiological and clinical characteristics of male patients with condyloma acuminatum (CA) in Liaocheng area, as well as to improve the understanding of human papillomavirus (HPV) infection and put forward targeted prevention and treatment measures. Methods The clinical data of 159 male CA patients who admitted to Liaocheng People's Hospital from January 2021 to January 2022 were collected, and the epidemiological characteristics, clinical manifestations, infection sites, HPV gene subtypes and other information were analyzed retrospectively. Results Most of the 159 CA patients (range from 15 to 77 years old) were 31-40 years old (31.45%, 50/159), more than half of them had smoking history, and more than 60% had low income (<5 000 yuan/month), multiple sexual partners (≥2) and no condom use habit, 70.44% of the patients had prepuce long combined with prepuce balanitis. 91 cases (57.23%) were single infection, 102 cases (64.15%) were simple low-risk HPV infection. The analysis of risk factors between mixed infection and simple low-risk infection found statistically significant differences in age≤ 40 years old, unmarried, or less affected by education duration of 15 years or less, engaged in the business or service industry, the number of sexual partners or 2, knew not to clean and not to use condoms, while differences in smoking history, alcohol history, monthly income level, and age at first sexual intercourse were not statistically significant. Low-risk HPV6 and/or HPV11 were detected in 139 cases (87.42%). Fifty-seven patients (35.85%) were infected with at least one high-risk HPV. 72.33% of the patients had multiple warts, and the most common sites were around the coronal sulcus and frenulum of the penis Conclusions The incidence of multiple infections and high-risk subtypes is high in male CA patients in Liaocheng area, and most of the patients have low income, low education level and multiple sexual partners. Strengthening the treatment and education follow-up of this population may contribute to the treatment and prognosis of male CA in this area.

4.
Water Sci Technol ; 86(7): 1719-1732, 2022 Oct.
Article in English | MEDLINE | ID: mdl-36240307

ABSTRACT

The application of membrane technology in the field of water treatment was increasingly widespread, but membrane fouling still restricted its development, and the membrane needed to be chemically cleaned. This research focused on the high-efficiency pickling technology of ceramic membrane, and developed the cleaning technology of ceramic membrane in cooperation with surfactant. In the experiment, the municipal secondary effluent was used as the raw water, and the single-step, mixed and step-by-step cleaning effects of three strong acids, three weak acids and surfactants on ceramic membranes and polyvinylidene difluoride (PVDF) membranes were investigated. For ceramic membrane, the optimal cleaning combination was H2SO4 first and then DTAC, and the flux recovery rate could reach 96.94%; for PVDF membrane, the optimal cleaning combination was HNO3 first and then H2SO4, and the flux recovery rate could reach 93.72%. In addition, the surface of initial, polluted, and cleaned membranes were analyzed by scanning electron microscope and contact angle, and the fouling mechanism of the ceramic membrane was analyzed. The results showed that through physical cleaning and chemical cleaning, most of the pollutants on the membrane surface and pores were removed. The cleaning method can effectively control the membrane pollution.


Subject(s)
Environmental Pollutants , Water Purification , Ceramics , Fluorocarbon Polymers , Membranes, Artificial , Polyvinyls , Surface-Active Agents , Technology , Water Purification/methods
5.
Environ Technol ; : 1-14, 2022 Aug 11.
Article in English | MEDLINE | ID: mdl-35924836

ABSTRACT

In this study, a flat sheet ceramic membrane experimental device was constructed, and the thermodynamics of membrane fouling interface was studied for oilfield produced water. The flux of ceramic membrane in three kinds of model solutions were measured with time, as well as the surface tension, contact Angle and Zeta potential of solid. The thermodynamic mechanism of membrane fouling interface combined with XDLVO theory were explored for three kinds of model solutions. The thermodynamic study of the interface of ceramic plate membrane shows that the total interaction energy between membrane and oil droplets decreases with the increase of the distance between two interfaces at initial stage of membrane fouling, and finally transforms from the mutual attraction to the mutual repulsion. The total interaction energy between reservoir and oil droplet is shown as mutual attraction, and the total interaction energy decreases with the increase of the distance between reservoir and oil droplet interface. The zeta potential of crude oil was affected by salinity to some extent. The electrostatic shielding effect of the salt ions leads to a decrease in the ζ-potential of the three solutions. They are in the order: model solution A > model solution B > model solution C. This leads to a decrease in the electrostatic interaction (EL). And since the oil layer has the same composition as the oil droplets, the EL interactions in the three solutions can behave as mutual repulsion.

6.
Front Bioeng Biotechnol ; 10: 836042, 2022.
Article in English | MEDLINE | ID: mdl-35284411

ABSTRACT

Objective: To systematically review in vitro studies that evaluated the effects of plant extracts on dentin bonding strength. Materials and Methods: Six electronic databases (PubMed, Embase, VIP, CNKI, Wanfang and The Cochrane Library) were searched from inception to September 2021 in accordance with the Preferred Reporting Items for Systematic Reviews (PRISMA). In vitro studies that compared the performance of dental adhesives with and without the plant extracts participation were included. The reference lists of the included studies were manually searched. Two researchers carried out study screening, data extraction and risk of bias assessment, independently and in duplicate. Meta-analysis was conducted using Review Manager 5.3. Results: A total of 62 studies were selected for full-text analysis. 25 articles used the plant extracts as primers, while five added the plant extracts into adhesives. The meta-analysis included 14 articles of in vitro studies investigating the effects of different plant extract primers on dentin bonding strength of etch-and-rinse and self-etch adhesives, respectively. The global analysis showed statistically significant difference between dental adhesives with and without plant extract primers. It showed that the immediate bond strength of dental adhesives was improved with the application of plant extract primers. Conclusion: The application of proanthocyanidin (PA) primers have positive effect on the in vitro immediate bonding strength of dental adhesives irrespective of etch-and-rinse or self-etch modes.

7.
Clin Oral Investig ; 24(6): 2079-2089, 2020 Jun.
Article in English | MEDLINE | ID: mdl-31705307

ABSTRACT

OBJECTIVES: To achieve in vitro remineralization of enamel white spot lesions (WSLs) via a mesoporous delivery system of amorphous calcium phosphate (ACP) precursors. MATERIALS AND METHODS: Amine-functionalized expanded pore mesoporous silica (aMSN) was loaded with polyacrylic acid-stabilized amorphous calcium phosphate (PAA-ACP) to develop a carrier-based delivery system (PAA-ACP@aMSN). Thirty-six artificial WSLs samples were created and randomly assigned to three treatments: artificial saliva solution (negative control, n = 12), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) slurry (n = 12), and PAA-ACP@aMSN slurry (n = 12). Surface microhardness, Raman intensity, and color were measured before/after artificial demineralization and after remineralization treatments to evaluate the remineralization level of each sample. SEM images were taken on the surface and cross-section of samples to observe microstructure changes. RESULTS: The surface microhardness recovery ratio (%SMHRR), Raman intensity change ratio (%ICR), and color recovery ratio (%CRR) were not significantly different between CPP-ACP and PAA-ACP@aMSN groups (P > 0.05), but both of them had significantly higher %SMHRR, %ICR, and %CRR values than negative control (P < 0.01). SEM images showed that apparent enamel prism imprints and inter-prism gaps in negative control were masked by mineral deposition in the PAA-ACP@aMSN and CPP-ACP groups. CONCLUSIONS: PAA-ACP@aMSN has an ability to remineralize enamel WSLs. CLINICAL RELEVANCE: The carrier-based amorphous calcium phosphate delivery system has great potential to serve as a remineralizing agent for the treatment of WSLs.


Subject(s)
Dental Caries , Tooth Remineralization , Calcium Phosphates , Cariostatic Agents , Caseins , Dental Caries/drug therapy , Dental Enamel , Humans
8.
World J Urol ; 37(6): 1075-1084, 2019 Jun.
Article in English | MEDLINE | ID: mdl-30612154

ABSTRACT

PURPOSE: We performed a meta-analysis to confirm the efficacy and safety of continuous saline bladder irrigation compared with intravesical chemotherapy after transurethral resection for the treatment of non-muscle invasive bladder cancer. METHODS: Randomized controlled trials of continuous saline bladder irrigation compared with intravesical chemotherapy were searched using MEDLINE, EMBASE, and the Cochrane Controlled Trials Register. The data were evaluated and statistically analyzed using RevMan version 5.3.0. RESULTS: Four studies including 861 participants which compared continuous saline bladder irrigation with intravesical chemotherapy were considered. One-year recurrence-free survival [odds ratio (OR) = 0.76, 95% CI = 0.55-1.05, p = 0.09]; 2-year recurrence-free survival (OR = 0.94, 95% CI = 0.71-1.25, p = 0.68); the median period to first recurrence (OR = - 1.01, 95% CI = - 2.96 to 0.94, p = 0.31); the number of tumor progression (OR = 0.80, 95% CI = 0.54-1.17, p = 0.25); and the number of recurrence during follow-up (OR = 1.12, 95% CI = 0.84-1.50, p = 0.43) suggested that two methods of postoperative perfusion had no significant differences. In terms of safety, including macrohematuria, frequency of urination and bladder irritation symptoms, continuous saline bladder irrigation showed better tolerance than intravesical chemotherapy. CONCLUSION: Continuous saline bladder irrigation seems to provide a better balance between prevention of recurrence and local toxicities than intravesical chemotherapy after transurethral resection of bladder tumors.


Subject(s)
Saline Solution/administration & dosage , Urinary Bladder Neoplasms/therapy , Administration, Intravesical , Antineoplastic Agents/administration & dosage , Combined Modality Therapy , Cystectomy/methods , Humans , Randomized Controlled Trials as Topic , Saline Solution/adverse effects , Therapeutic Irrigation/adverse effects , Therapeutic Irrigation/methods , Treatment Outcome , Urethra , Urinary Bladder Neoplasms/drug therapy , Urinary Bladder Neoplasms/surgery
9.
Biomed Pharmacother ; 109: 930-937, 2019 Jan.
Article in English | MEDLINE | ID: mdl-30551547

ABSTRACT

Endothelial cells are vital to blood coagulation and maintain whole body hemostasis. Binding of endothelial cells to endothelial protein C receptor (EPCR) and thrombomodulin (TM) is essential to the formation of activated protein C (APC), one of the key factors regulating blood coagulation. In our study, we showed that resistin, an adipocyte hormone, suppresses thrombin-induced protein C activation in endothelial cells. Resistin treatment results in a reduction in EPCR expression, but not TM. Mechanistically, we demonstrate that resistin induces expression of the nuclear transcription factor SP-1, which could lead to downregulation of EPCR. Both inhibition and silencing of SP1 protein abolishes abnormal APC generation induced by resistin. Collectively, our data support a new role of resistin in disturbing APC formation.


Subject(s)
Endothelial Protein C Receptor/antagonists & inhibitors , Endothelial Protein C Receptor/biosynthesis , Human Umbilical Vein Endothelial Cells/metabolism , Protein C/metabolism , Resistin/pharmacology , Sp1 Transcription Factor/biosynthesis , Dose-Response Relationship, Drug , Gene Expression , Human Umbilical Vein Endothelial Cells/drug effects , Humans , Sp1 Transcription Factor/genetics
10.
Biochem Biophys Res Commun ; 502(3): 299-306, 2018 07 20.
Article in English | MEDLINE | ID: mdl-29772237

ABSTRACT

Accumulating evidence has indicated that long non-coding RNAs (lncRNAs) are critically involved in tumor progression. In current study, we reported a novel lncRNA signature correlated with bladder cancer development. Particularly, the lncRNA long stress-induced noncoding transcript 5 (LSINCT5) is significantly upregulated in human bladder cancer cell lines and tumor specimens. Meanwhile, high LSINCT5 expression correlates with poor prognosis, enhances tumor sphere formation and invasion in vitro. In vivo xenograft tumor growth is also elevated by LSINCT5 overexpression. Mechanistic investigations showed that LSINCT5 could physically interact with NCYM, a de novo gene product from the MYCN cis-antisense RNA and inhibit GSK3ß activity leading to enhanced Wnt/ß-catenin signaling activation and epithelial mesenchymal transition (EMT). Taken together, our findings have created a novel LSINCT5 mediated process which facilitates bladder cancer progression and may provide a potential target for therapeutic intervention.


Subject(s)
Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , Urinary Bladder Neoplasms/genetics , Urinary Bladder Neoplasms/metabolism , Animals , Disease Progression , Epithelial-Mesenchymal Transition , Female , Gene Knockdown Techniques , Glycogen Synthase Kinase 3 beta/metabolism , Heterografts , Humans , Mice , Mice, Inbred BALB C , Mice, Nude , RNA, Long Noncoding/antagonists & inhibitors , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism , Spheroids, Cellular/metabolism , Spheroids, Cellular/pathology , Up-Regulation , Urinary Bladder Neoplasms/pathology , Wnt Signaling Pathway , beta Catenin/metabolism
11.
J Cell Biochem ; 2017 Oct 05.
Article in English | MEDLINE | ID: mdl-28980707

ABSTRACT

BACKGROUND: Epigenetic factors of microRNAs (miRNAs) are important biomarkers and modulators in human prostate cancer (PCa). In this work, we characterized the expression, biomarker-potential and functional regulation of miR-588 in PCa. METHODS: Endogenous miR-588 levels were quantified by qRT-PCR in both prostate-specific antigen (PSA)-negative and PSA-positive PCa cell lines, as well as human PCa tumors. The associations between endogenous miR-588 and PCa patients' clinical outcomes and postoperative overall survival were statistically examined. Moreover, in both PSA-negative DU145 and PSA-positive LNCaP, downregulation of miR-588 was achived by transduction of miR-588 inhibitor lentivirus. The subsequent effects of miR-588 downregulation on PCa cell developments were investigated both in vitro and in vivo. RESULTS: MiR-588 was profoundly upregulated in both PSA-negative and PSA-positive PCa cells, as well as in PCa tumors. Significant miR-588 upregulation was found to be closely associated with PCa patients' poor clinical outcomes and shorter postoperative overall survivals. In DU145 and LNCaP cell lines, lentiviral transduction markedly downregulated endogenous miR-588 levels. MiR-588 downregulation was shown to profoundly inhibit PCa proliferation in vitro and xenograft in vivo. CONCLUSION: Aberrant upregulation of endogenous miR-588 in PCa patients may be a prognostic biomarker, indicative of their poor clinical outcomes. Inhibiting endogenous miR-588 may also serve as a therapeutic target for PCa treatment. This article is protected by copyright. All rights reserved.

12.
J Adhes Dent ; : 229-237, 2017 Jun 08.
Article in English | MEDLINE | ID: mdl-28597009

ABSTRACT

PURPOSE: To investigate the effect of the dimethyl-sulfoxide wet-bonding technique on composite-dentin bonds and to explore its potential mechanism. MATERIALS AND METHODS: Thirty human third molars were segmented, ground, etched, and randomly divided into three groups according to the following pretreatments: 1. water; 2. ethanol; 3. 50% (v/v) dimethyl sulfoxide (DMSO). Then, Single Bond 2 was applied and composite buildups were constructed. After 24 h of water storage or 10,000 cycles of thermocycling, the microtensile bond strength (MTBS) and nanoleakage were measured. Contact angle measurement, Masson's trichrome staining, and in situ zymography were used to explore the possible action mechanism of DMSO on adhesive-dentin interfaces. RESULTS: DMSO pretreatment prevented the decline of thermocycled MTBS (p < 0.05) without affecting the immediate MTBS (p > 0.05) compared to the water wet-bonded group. Nanoleakage expression in the thermocycled DMSO wet-bonded group was also less than that in the thermocycled water-wet group (p < 0.05). Moreover, DMSO decreased the contact angle of the dentin surfaces (p < 0.05), reduced the amount of collagen exposure (p < 0.05), and decreased the collagenolytic activity in the hybrid layer (p < 0.05). CONCLUSION: The 50% DMSO pretreatment was effective in increasing the wettability of the etched dentin surface, promoting the penetration of the adhesive monomer, and enhancing the stability of the dentin collagen at the adhesive- dentin interface. All these changes may lead to higher quality dentin bonds, suggesting that DMSO wet bonding is a viable alternative to improve the durability of dentin bonding.

13.
Methods Enzymol ; 565: 423-58, 2015.
Article in English | MEDLINE | ID: mdl-26577741

ABSTRACT

Chemical and chemi-enzymic methods are discussed for the preparation of monosaccharide isotopomers that are singly and multiply labeled with (13)C, (2)H, (17/18)O, and (15)N isotopes. The discussion focuses primarily on chemical methods to incorporate stable isotopes into monosaccharides and not on methods to assemble labeled monosaccharides into more complex biomolecules such as oligosaccharides or oligonucleotides. Two primary isotope insertion reactions are considered: cyanohydrin reduction (CR) and molybdate-catalyzed epimerization (MCE). Both methods are described in detail, including discussions of their mechanistic features, and their advantages and limitations. The integration of CR, MCE, and other chemical synthetic processes with enzyme-mediated synthesis is also discussed to illustrate how a wide range of singly and multiply labeled monosaccharides can be prepared for subsequent use in the assembly of more complex isotopically labeled biomolecules.


Subject(s)
Isotope Labeling , Monosaccharides/chemistry
14.
J Org Chem ; 72(8): 3081-4, 2007 Apr 13.
Article in English | MEDLINE | ID: mdl-17371071

ABSTRACT

Reaction of a galactosylated 2-C-(hydroxymethyl)-tetrofuranose with paramolybdate ion-exchange resin in aqueous solution at 67 degrees C gave an equililibrium mixture containing the reactant aldofuranose (42%) and a 2-ketopentofuranose galactosylated at O1 (58%). Observation of this stereospecific rearrangement supports prior arguments that substituents at C2 of the branched-chain aldofuranose reactant are located in a sterically accessible pocket of the putative dimolybdate-saccharide reactive complex during epimerization. This rearrangement provides a new and convenient route to 2-ketosugars glycosylated at the exocyclic C1 position.


Subject(s)
Anions/chemistry , Disaccharides/chemistry , Furans/chemistry , Molybdenum/chemistry , Water/chemistry , Anion Exchange Resins , Carbohydrate Conformation , Catalysis , Chromatography, Ion Exchange , Stereoisomerism
15.
J Org Chem ; 71(2): 466-79, 2006 Jan 20.
Article in English | MEDLINE | ID: mdl-16408953

ABSTRACT

[reaction: see text] A series of 2-amino-2-deoxy-D-[1-13C]aldohexoses and their methyl glycosides was prepared with use of a simplified cyanohydrin reduction route. Four d-aldopentosylamines (arabino, lyxo, ribo, xylo) were prepared from the corresponding D-aldopentoses by reaction with NH3(g) in MeOH solvent, isolated in solid form, and characterized by 13C and 1H NMR. Hydrolysis of beta-D-xylopyranosylamine was studied using 13C-labeled substrates to establish optimal solution conditions for cyanohydrin formation. Major hydrolytic intermediates were observed and identified by time-lapse 1D and 2D NMR analyses of reaction mixtures. The aldopentosylamines were subsequently employed in cyanohydrin reduction reactions with K13CN to yield C2-epimeric [1-13C]2-aminosugars, which were separated by chromatography on ion-exchange columns. N-Acetylation and methyl glycosidation followed by chromatography gave pure 2-acetamido-2-deoxy-D-[1-13C]aldohexopyranosides. J(CH) and J(CC) spin-spin coupling constants involving the labeled anomeric carbon were measured and compared to those observed previously in methyl D-[1-13C]aldohexopyranosides. In parallel studies, theoretical J-couplings were calculated in model N-acetylated aldopyranosides using density functional theory (DFT) to predict the effect of OH vs NHCOCH(3) substitution at C2 on J(CH) and J(CC) values in aldopyranosyl rings. The synthetic method was also modified to accommodate (15)N- and (13)C-labeling within the N-acetyl side-chain, and some J-couplings involving 1H, 13C, and 15N atoms in 2-[1,2-13C2;15N]acetamido-2-deoxy-D-[1-13C]glucose were measured and interpreted.


Subject(s)
Glycosides/chemical synthesis , Hexoses/chemical synthesis , Carbohydrate Conformation , Carbohydrate Sequence , Carbon Isotopes , Chromatography, High Pressure Liquid , Glycosides/chemistry , Hexoses/chemistry , Hydrogen , Magnetic Resonance Spectroscopy/methods , Mass Spectrometry , Molecular Sequence Data , Nitrogen , Oligosaccharides/chemical synthesis
16.
J Am Chem Soc ; 126(48): 15668-85, 2004 Dec 08.
Article in English | MEDLINE | ID: mdl-15571389

ABSTRACT

Methyl alpha- and beta-pyranosides of d-glucose and d-galactose 1-4 were prepared containing single sites of (13)C-enrichment at C4, C5, and C6 (12 compounds), and (1)H and (13)C[(1)H] NMR spectra were obtained to determine a complete set of J-couplings ((1)J, (2)J, and (3)J) involving the labeled carbon and nearby protons and carbons within the exocyclic hydroxymethyl group (CH(2)OH) of each compound. In parallel theoretical studies, the dependencies of (1)J, (2)J, and (3)J involving (1)H and (13)C on the C5-C6 (omega) and C6-O6 (theta;) torsion angles in aldohexopyranoside model compounds were computed using density functional theory (DFT) and a special basis set designed to reliably recover the Fermi contact contribution to the coupling. Complete hypersurfaces for (1)J(C5,C6), (2)J(C5,H6)(R), (2)J(C5,H6)(S), (2)J(C6,H5), (2)J(C4,C6), (3)J(C4,H6)(R), (3)J(C4,H6)(S), and (3)J(C6,H4), as well as (2)J(H6)(R)(,H6)(S), (3)J(H5,H6)(R), and (3)J(H5,H6)(S), were obtained and used to parametrize new equations correlating these couplings to omega and/or theta;. DFT-computed couplings were also tested for accuracy by measuring J-couplings in (13)C-labeled 4,6-O-ethylidene derivatives of d-glucose and d-galactose in which values of omega and theta; were constrained. Using a new computer program, Chymesa, designed to utilize multiple J-couplings sensitive to exocyclic CH(2)OH conformation, the ensemble of experimental couplings observed in 1-4 were analyzed to yield preferred rotamer populations about omega and theta;. Importantly, due to the sensitivity of some couplings, most notably (2)J(H6)(R)(,H6)(S), (2)J(C5,H6)(R), and (2)J(C5,H6)(S), to both omega and theta;, unique information on correlated conformation about both torsion angles was obtained. The latter treatment represents a means of evaluating correlated conformation in 1,6-linked oligosaccharides, since psi and theta; are redundant in these linkages. In the latter regard, multiple, redundant scalar couplings originating from both sides of the glycosidic linkage can be used collectively to evaluate conformational correlations between psi/theta; and C5-C6 bond rotamers.


Subject(s)
Galactose/analogs & derivatives , Glucose/analogs & derivatives , Nuclear Magnetic Resonance, Biomolecular/methods , Carbohydrate Conformation , Carbohydrate Sequence , Carbon Isotopes , Galactose/chemical synthesis , Galactose/chemistry , Glucose/chemical synthesis , Glucose/chemistry , Isotope Labeling , Models, Chemical , Molecular Sequence Data , Polysaccharides/chemistry , Protons , Pyrans/chemical synthesis , Pyrans/chemistry
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