Search

Background and objective Recent observational studies have shown that sleep apnoea (SA) is associated with increased risk of incident CKD. However, the contribution of SA relative to common traditional CKD risk factors remains unknown. The aims of this study were to investigate the long-term risk of incident CKD events following SA diagnosis and compare the relative contributions of SA, diabetes and hypertension. Methods Data were retrieved from Taiwan's National Health Insurance Research Database during the period between 2000 and 2010 for this retrospective cohort study. The cohorts are composed of patients (age ≥ 20 years) newly diagnosed with SA and matched subjects without SA. The two cohorts were followed until the occurrence of CKD, death or the end of 2010. Results The sample is composed of 43 434 individuals (8687 patients with SA and 34 747 matched non-SA subjects). A total of 157 new CKD events in patients with SA and 298 events in the matched non-SA cohort were recorded during a mean follow-up period of 3.9 years (incidence rates, 4.5 and 2.2/per 1000 person-years). The risk of CKD development was greater among patients with SA than in the matched non-SA cohort (adjusted hazard ratio (aHR) 1.58, 95% confidence interval ( CI): 1.29–1.94). The contribution of SA to the CKD hazard was similar to that of hypertension (aHR 1.17, 95% CI: 0.68–2.01, P = 0.56), whereas that of diabetes remained significantly higher (aHR 2.17, 95% CI: 1.21–3.90, P = 0.01). Conclusion SA was associated with an increase in the risk of CKD incidence similar to that of hypertension. See Editorial, page 578

Glucoamylases are responsible for hydrolysis of starch and polysaccharides to yield β-d-glucose. Rhizopus oryzae glucoamylase (RoGA) is composed of an N-terminal starch binding domain (SBD) and a C-terminal catalytic domain connected by an O-glycosylated linker. Two carbohydrate binding sites in RoSBD have been identified, site I is created by three highly conserved aromatic residues, Trp47, Tyr83, and Tyr94, and site II is built up by Tyr32 and Phe58. Here, the two crystal structures of RoSBD in complex with only α-(1,6)-linked isomaltotriose (RoSBD-isoG3) and isomaltotetraose (RoSBD-isoG4) have been determined at 1.2 and 1.3 A, respectively. Interestingly, site II binding is observed in both complexes, while site I binding is only found in the RoSBD-isoG4 complex. Hence, site II acts as the recognition binding site for carbohydrate and site I accommodates site II to bind isoG4. Site I participates in sugar binding only when the number of glucosyl units of oligosaccharides is more than three. Taken together, two carbohydrate binding sites in RoSBD cooperate to reinforce binding mode of glucoamylase with polysaccharides as well as the starch. Proteins 2014; 82:1079–1085. © 2013 Wiley Periodicals, Inc.

Triosephosphate isomerase (TIM) catalyzes the interconversion between dihydroxyacetone phosphate and D-glyceraldehyde-3-phosphate in the glycolysis-gluconeogenesis metabolism pathway. The Helicobacter pylori TIM gene (HpTIM) was cloned, and HpTIM was expressed and purified. The enzymatic activity of HpTIM for the substrate GAP was determined (K(m) = 3.46 +/- 0.23 mM and k(cat) = 8.8 x 10(4) min(-1)). The crystal structure of HpTIM was determined by molecular replacement at 2.3 A resolution. The overall structure of HpTIM was (beta/alpha)beta(beta/alpha)(6), which resembles the common TIM barrel fold, (beta/alpha)(8); however, a helix is missing after the second beta-strand. The conformation of loop 6 and binding of phosphate ion suggest that the determined structure of HpTIM was in the "closed" state. A highly conserved Arg-Asp salt bridge in the "DX(D/N)G" motif of most TIMs is absent in HpTIM because the sequence of this motif is "(211)SVDG(214)." To determine the significance of this salt bridge to HpTIM, four mutants, including K183S, K183A, D213Q, and D213A, were constructed and characterized. The results suggest that this conserved salt bridge is not essential for the enzymatic activity of HpTIM; however, it might contribute to the conformational stability of HpTIM.

A novel class of nucleosides with the C1, atom bonded to three hetero atoms was synthesized. 2′-Thia-2′,3′-dideoxycytidine was the pilot compound of this series. (±)-β-2′-Thia-1′,3′-dideoxycytidine (6) and (±)-α-2′-thia-2′,3′-dideoxycytidine (7) were synthesized from (±)-3-mercapto-1,2-propanediol. The synthesis of the enantiomerically pure 2′-thia-2′,3′-dideoxycytidines (α-D-form, β-D-form, α-1-form and β-L-form) from optically pure (S)-(2,2-dimethyl-1,3-dioxalan-yl)methyl p-toluenesulfonate (8) and its (R)-isomer 18 was also described. The preliminary biological results showed that (+)-β-D-2′-thia-2′,3′-dideoxycytidine (26) was the most active against human hepatitis B virus with an ED50 of 3 μM.

6-Arylthio and 6-arylselenoacyclonucleosides was synthesized and tested for the ability to inhibit replication of HIV-1. Lithiation of acyclonucleosides with LDA followed by reaction with the electrophiles phenyl disulfide, diphenyl diselenide, 2,2′-dipyrdyl disulfide or 2,2′-dipyridyl diselenide afforded 6-(arylthio or arylseleno)acyclonucleosides 5a-c, 6, 7, 9, 15a-c, 17a-c. Compounds 19a-c and 20a-c were obtained by deprotection of corresponding TBDMS derivatives. Dehydrated products 16a, and 18a-c were also formed during the reactions. 5-Ethyl-6-(α-pyridylthio or α-pyridylseleno) disubstituted acyclouracils 6 and 7 were more active against HIV-1 in both MT-2 and CEM-IW cell lines than AZT, DDC, DDI or D4T. The EC50 of 6 against HIV-1 in CEM-IW cell was in the nanomolar range with a therapeutic index of 1100.

Blends between poly(acrylic acid) and two different poly(oxyethylenes), (1) polyethylene glycol (PEG-1000) and (2) poly(oxyethylene) (20) sorbitan monooleate (Tween-80), were studied by differential scanning calorimetry. The glass transition temperatures, Tg, of the various compositions of these blends were found to follow Fox's equation. At room temperature, blends containing no more than 60% PEG-1000 were amorphous and exhibited only a single glass transition. For these blends with PEG-1000, the glass transition temperatures for the annealed samples were higher than for the quenched samples due to the formation of a PEG crystalline phase. It was also found that addition of an amorphous polymer such as poly(acrylic acid) significantly reduced the degree of crystallinity of a semicrystalline polymer such as poly(oxyethylene). The Tween-80 systems did not show phase separation at room temperature. The compatibility between this poly(acrylic acid) and this poly(oxyethylene) was attributed to hydrogen bonding and to the lower crystalline lattice energy of this poly(oxyethylene) through its effect on its ideal solution solubility. © 1993 John Wiley & Sons, Inc.

5-Benzyl and 5-benzyloxybenzyl-substituted 3′-azido-2′,3′-dideoxyuridine, (8a and 8b), 3′-halogeno-2′,3′-dideoxyuridine, 9a, 9b, 10a, 10b, 11a and 11b, and 2′,3′-dideoxyuridine, 12a and 12b, of Scheme I were synthesized as potential anti AIDS agents. Synthesis of epimers of 8a and 8b, 5-benzyl- and 5-benzyloxybenzyl-1-(3′-azido-2′,3′-dideoxy-β-D-threo-pentafuranosyl)uracil, 15a and 15b, and 5-benzyl- and 5-benzyloxy-5′-azido-2′,5′-dideoxyuridine, 16a and 16b, shown in Scheme II, were also reported.

1'-Halogenomethyl, 1'-azidomethyl and 1'-disubstituted aminomethyl derivatives of BAU (5-benzylacyclouridine) and BBAU (5-benzyloxybenzylacyclouridine) were synthesized in the course of our studies of benzylacyclouridines. Two new and more convenient preparations of the previously known aminomethyl-and hydroxyymethyl-parent compounds of these two series, AM-BAU, AM-BBAU and HM-BBAU are also reported. These compounds were synthesized during a search for potential antiviral agents and pyrimidine phosphorylase inhibitors

6-Arylthio and 6-arylselenoacyclonucleosides was synthesized and tested for the ability to inhibit replication of HIV-1. Lithiation of acyclonucleosides with LDA followed by reaction with the electrophiles phenyl disulfide, diphenyl diselenide, 2,2′-dipyrdyl disulfide or 2,2′-dipyridyl diselenide afforded 6-(arylthio or arylseleno)acyclonucleosides 5a-c, 6, 7, 9, 15a-c, 17a-c. Compounds 19a-c and 20a-c were obtained by deprotection of corresponding TBDMS derivatives. Dehydrated products 16a, and 18a-c were also formed during the reactions. 5-Ethyl-6-(α-pyridylthio or α-pyridylseleno) disubstituted acyclouracils 6 and 7 were more active against HIV-1 in both MT-2 and CEM-IW cell lines than AZT, DDC, DDI or D4T. The EC50 of 6 against HIV-1 in CEM-IW cell was in the nanomolar range with a therapeutic index of 1100.

A novel class of nucleosides with the C1, atom bonded to three hetero atoms was synthesized. 2′-Thia-2′,3′-dideoxycytidine was the pilot compound of this series. (±)-β-2′-Thia-1′,3′-dideoxycytidine (6) and (±)-α-2′-thia-2′,3′-dideoxycytidine (7) were synthesized from (±)-3-mercapto-1,2-propanediol. The synthesis of the enantiomerically pure 2′-thia-2′,3′-dideoxycytidines (α-D-form, β-D-form, α-1-form and β-L-form) from optically pure (S)-(2,2-dimethyl-1,3-dioxalan-yl)methyl p-toluenesulfonate (8) and its (R)-isomer 18 was also described. The preliminary biological results showed that (+)-β-D-2′-thia-2′,3′-dideoxycytidine (26) was the most active against human hepatitis B virus with an ED50 of 3 μM.

1'-Halogenomethyl, 1'-azidomethyl and 1'-disubstituted aminomethyl derivatives of BAU (5-benzylacyclouridine) and BBAU (5-benzyloxybenzylacyclouridine) were synthesized in the course of our studies of benzylacyclouridines. Two new and more convenient preparations of the previously known aminomethyl-and hydroxyymethyl-parent compounds of these two series, AM-BAU, AM-BBAU and HM-BBAU are also reported. These compounds were synthesized during a search for potential antiviral agents and pyrimidine phosphorylase inhibitors

5-Benzyl and 5-benzyloxybenzyl-substituted 3′-azido-2′,3′-dideoxyuridine, (8a and 8b), 3′-halogeno-2′,3′-dideoxyuridine, 9a, 9b, 10a, 10b, 11a and 11b, and 2′,3′-dideoxyuridine, 12a and 12b, of Scheme I were synthesized as potential anti AIDS agents. Synthesis of epimers of 8a and 8b, 5-benzyl- and 5-benzyloxybenzyl-1-(3′-azido-2′,3′-dideoxy-β-D-threo-pentafuranosyl)uracil, 15a and 15b, and 5-benzyl- and 5-benzyloxy-5′-azido-2′,5′-dideoxyuridine, 16a and 16b, shown in Scheme II, were also reported.

Nucleoside analogues of uridine, 5-bromo-, 5-iodo-, and 5-fluorouridines, thymidine and cytidine were prepared by condensing appropriately substituted 2,4-dimethoxypyrimidines with an acyclic side chain in the form of a benzoylated halo-ether, and subsequent removal of the protecting benzoyl group in base. The 2′-O-p-tosylates of these nucleoside analogues could then be modified to 2′-halo-, azido-, and amino derivatives. Many of these compounds are competitive inhibitors of uridine phosphorylase in vitro, the most active being 5-methyl-1-(2′-hydroxyethoxymethyl)uracil.

A useful, facile procedure for preparing seleno-heterocyclic compounds is reported. Treatment of cAMP, AMP, adenosine, 2-aminoadenosine, adenine arabinoside and formycin with hydrogen selenide in aqueous pyridine at 65° for 1.5-5 days gave the corresponding seleno compounds in good yield, while these compounds were relatively inert to hydrogen sulfide. A reaction mechanism is proposed.

Amino analogs of BAU (5-benzylacyclouridine) and BBAU (5-benzyloxybenzylacyclouridine) and their 2′-hydroxymethyl derivatives were synthesized for evaluation as inhibitors of uridine phosphorylase and hence potential cancer chemotherapeutic agents. Both aminomethyl analogs were found to be potent inhibitors of this enzyme and good potentiators of the anti-tumor action of FUdR.

Racemic 2′-aminomethyl-5-benzyl-acyclouridine (AM-BAU, 5) and 2′-aminomethyl-5-benzyloxybenzyla-cyclouridine (AM-BBAU, 6) have been found to be very active inhibitors of uridine phosphorylase [1]. Their enantiomers were synthesized from chiral 2,2-dimethyl-1,3-dioxolane-4-methanol (7a,b). S-(—)-AM-BAU (5a) and S-(—)-AM-BBAU (6a) were prepared from the R-(—) isomer 7a, and R(+)-AM-BAU (5b) and R-(+)-AM-BBAU (6b) from the S-(+) isomer 7b. A different route from the S-(+) isomer 7b to S-(—)-AM-BBAU (6a) was also determined to be feasible.

Amino analogs of BAU (5-benzylacyclouridine) and BBAU (5-benzyloxybenzylacyclouridine) and their 2′-hydroxymethyl derivatives were synthesized for evaluation as inhibitors of uridine phosphorylase and hence potential cancer chemotherapeutic agents. Both aminomethyl analogs were found to be potent inhibitors of this enzyme and good potentiators of the anti-tumor action of FUdR.

6-Chloro-9-(β-D-arabinofuranosyl)purine served as an intermediate for the chemical synthesis of a series of 6-substituted selenopurine arabinosides. In an in vitro test using murine leukemic cells (L-5178Y) these 6-substituted selenopurine arabinosides showed some cytotoxicity. Lengthening the side chain had no effect on their cytotoxicity. Selenourea was a useful reagent for synthesizing selenopurines, selenopurine nucleosides, and selenopurine arabinoside under mild conditions.

Racemic 2′-aminomethyl-5-benzyl-acyclouridine (AM-BAU, 5) and 2′-aminomethyl-5-benzyloxybenzyla-cyclouridine (AM-BBAU, 6) have been found to be very active inhibitors of uridine phosphorylase [1]. Their enantiomers were synthesized from chiral 2,2-dimethyl-1,3-dioxolane-4-methanol (7a,b). S-(—)-AM-BAU (5a) and S-(—)-AM-BBAU (6a) were prepared from the R-(—) isomer 7a, and R(+)-AM-BAU (5b) and R-(+)-AM-BBAU (6b) from the S-(+) isomer 7b. A different route from the S-(+) isomer 7b to S-(—)-AM-BBAU (6a) was also determined to be feasible.

Treatment of adenosine, 2-aminoadenosine, adenine arabinoside, formycin, 1-Me-AMP, cyclo-AMP, and 1-Me-cyclo-AMP with H2Se in aqueous pyridine gave the corresponding seleno compounds with good yield.

8-Bromoguanosine cyclic 3',5'-monophosphate, 8-bromoguanosine 5'-monophosphate, and 8-bromoguanosine served as intermediates for the chemical synthesis of a series of 8-substituted seleno cyclic nucleotides, nucleotides, and their nucleosides. Selenourea was found to be a useful reagent in synthesizing these seleno-substituted nucleoside, nucleotide, and cyclic nucleotide. A nucleic acid analyzer was used to study the hydrolysis of these cyclic nucleotides by phosphodiesterase. It was found that all of the 8-substituted selenoguanosine cyclic 3',5'-phosphates synthesized, except 8-MeSe-cGMP, were resistant to hydrolyze by phosphodiesterase. These 8-substituted seleno cyclic GMP derivatives showed some antitumor activities against murine leukemic cells (L5178Y) in vitro and in vivo.