Structural analysis of the reaction products of chitosan with o-, m- and p-phthalaldehydes

Chitosan, a $\text{(I}\text{a}\text{?}\text{4)-}\text{linked}$ 2-amino-2-deoxy-β-d-glucan, was allowed to react with o-, m- and p-phthalaldehydes in aqueous acetic acid-methanol at room temperature to give the corresponding Schiff's base derivative (d.s. ～ 1.0/hexosaminyl residue) in a gel form. The dry product was isolated in yields of 90–97%, and the fine structure was analysed. Both the crosslinking and N-formylbenzylidene structures were present in an almost equal molar ratio in the reaction product of chitosan with p-phthalaldehyde and at a molar ratio of 0.1:0.9 in the reaction product of chitosan with m-phthalaldehyde. However, both structures were absent in the reaction product of chitosan with o-phthalaldehyde, and an intramolecular cyclic structure was present.     

Biotransformation of p-, m-, and o-hydroxybenzoic acids by Panax ginseng hairy root cultures

The regioselective glycosylation of three isomers of hydroxybenzoic acids was observed in Panax ginseng hairy root cultures. p-Hydroxybenzoic acid (1) and m-hydroxybenzoic acid (2) were converted into their corresponding glycosides (1a and 2a) and glycosyl esters (1b and 2b) while no metabolite of o-hydroxybenzoic acid (3) was detected. A new compound, m-hydroxybenzoic acid β-d-xylopyranosyl (1 → 6)-β-d-glycopyranosyl ester (2c) was identified as a biotransformation product of 2. Further time-course studies of the biotransformation reactions showed that the glycosides were major products in the latter stage. The addition of carbohydrates or antioxidants increased glycosyl esters formation.     

A novel assay of glucuronidation of C- and N-hydroxylated metabolites of the carcinogen N-2-fluorenylacetamide

A method for the assay of glucuronidation of C- and N-hydroxylated metabolites of the carcinogen N-2-fluorenylacetamide is described. The method employs UDP-[U-14C ))glucuronic acid and Baker C18 extraction columns for separation of the glucuronides from their aglycones and from the glucuronic acid. The 14C-labeled glucuronides, generated by rat liver microsomes, are eluted from the columns with 30% (v/v) methanol after prewashing the columns and elution of the radioactivity of 14C-glucuronic acid with 1 mM ammonium acetate, pH 6.9. The radioactivity of the eluates is measured by scintillation counting. The method is modified for assays of glucuronidation of alpha-naphthol and p-nitrophenol in that 1 mM phosphoric acid is used instead of 1 mM ammonium acetate, and the method is potentially adaptable to other aglycones. By monitoring radioactivity or uv absorbance of the column eluates, it is shown that all aglycones, except p-nitrophenol, are retained on the columns during elution of their glucuronides with 30% (v/v) methanol and are eluted only when absolute methanol is used. The identity of the glucuronides is shown by their response to hydrolysis by beta-glucuronidase in the presence and absence of D-saccharic acid-1,4-lactone and, in some instances, by chromatographic and spectral analyses of the released aglycones.     

牛场肥水灌溉对土壤nirK、nirS型反硝化微生物群落结构的影响

以徐水县梁家营长期定位施肥试验田为研究对象,利用末端限制性片段长度多态性(T-RFLP)分析和克隆文库构建,研究了5种施肥处理(清水灌溉CK、无机肥灌溉CF、牛场肥水不同浓度、不同次数灌溉T4、T5和T11)下土壤中nirK、nirS型反硝化细菌群落多样性及其群落结构的演变。结果表明,不同施肥处理下nirK、nirS型反硝化细菌群落多样性无显著差异,但群落结构却有明显变化:nirK型反硝化细菌群落结构既受施肥种类又受施肥量影响,优势种群尤其对施肥种类和施肥量响应显著;nirS型反硝化细菌则主要受施肥种类影响,施肥量影响微弱。牛场肥水处理和无机肥处理分别促进和抑制不同的nirS型反硝化细菌,群落主成分受无机肥促进、牛场肥水抑制。系统发育分析结果表明,土壤中nirK型反硝化细菌主要与假单胞菌属(Pseudomonas)、产碱杆菌属(Alcaligenes)和根瘤菌属(Rhizobium)的反硝化细菌具有较近的亲缘关系;nirS型反硝化细菌主要与劳尔氏菌(Ralstonia)和红长命菌属(Rubrivivax)有较近的亲缘关系。试验土壤中反硝化微生物多与目前已报道的好氧反硝化细菌亲缘关系较近,这可能与微生物分析取自表层土有关。     

HybridRamphastos- toucans in captivity

Ohne Zusammenfassung     

Photooxidation of P-960 and photoreduction of P-800 (bacteriopheophytin b-800) in reaction centers from Rehodopseudomonas viridis. Exciton interaction between the pigment molecules

The light excitation of P-960 results in the oxidation of P-960 and the reduction of P-800 (bacteriophytin b-800) in the reaction centers from Rhodopseudomonas viridis. A negative 847 nm band of the circular dichroism spectrum disappears under P-960 photooxidation, while a positive 827 nm band disappears under P-800 photoreduction. Exciton interaction of the pigment molecules in the reaction center is discussed.     

Excision repair by human fibroblasts of DNA damaged by r-7, t-8-dihydroxy-t-9,10-OXY-7,8,9,10-tetrahydrobenzo(a)pyrene

Benzo(a)pyrene diol-epoxide I (r-7,t-8,dihydroxy-t-9,10 oxy-7,8,9,10 tetrahydrobenzo(a)pyrene) was used to treat either human adenovirus 5 or cultures of human fibroblasts. The survival of diol-epoxide I treated adenovirus was greater when infecting fibroblasts from normal persons than when infecting fibroblasts from patients with xeroderma pigmentosum (XP). One diol-epoxide I molecule bound per viral genome correlated with one lethal hit as measured using XP fibroblasts.Normal fibroblasts blocked in semi-conservative DNA synthesis incorporated into their DNA more [³H]thymidine in response to diol-epoxide I treatment than did XP fibroblasts, and also excised more diol-epoxide I from their DNA. All of the effects described above were similar to those obtained when the inactivating agent was ultraviolet light rather than benzo(a)pyrene diol-epoxide I.     

Biotransformations of ortho-, meta- and para-aromatic nitrocompounds by strains of Aspergillus terreus: Reduction of ketones and deracemization of alcohols

Seven strains of the fungus Aspergillus terreus isolated from several provenances in Brazil, catalyzed biotransformations of ortho-, meta- and para-nitrophenyl compounds at different pH values. ortho-Nitroacetophenone and meta-nitroacetophenone were transformed into (S)-(+)-1-(ortho-nitrophenyl)ethanol and (S)-(−)-1-(meta-nitrophenyl)ethanol with high enantiomeric excess (e.e. ≥98%) and conversion (≥98%) by all the strains used. Deracemization of (RS)-1-(meta-nitrophenyl)ethanol was obtained with high selectivity (e.e. up to ≥98%) and good conversion (c 98%). The biotransformations in acidic medium using these fungus strains were more efficient than under basic or neutral conditions.     

Synthesis of [2S-2-H]- and [2R-2-H]hexadecanoic acids

[2S-2-²H]- and [2R-2-²H]hexadecanoic acids were synthesized in overall yields of 59–67%. Methyl(2R)-2-hydroxyhexadecanoate, from the acid produced by Hansenula sydowiorum, was converted to the p-toluenesulphonate, reduced to trideutero alcohol with lithium aluminium deuteride and oxidized to [2S-2-²H]hexadecanoic acid. Methyl (2S)-2-chlorohexadecanoate, which was a by-product of tosylation and was also prepared by chlorinatioon of the hydroxy ester with thionyl chloride, on reduction and oxidation as before gave [2R-2-²H]-hexadecanoic acid. Intermediates were fully characterized, isotopic purity was 97% and optical purity was maintained throughout the syntheses. Attempts to reduce the tosyl or chloro groups, only, with sodium borodeuteride gave low yields probably due to preferential reduction of the ester group; 1,2-epoxyhexadecane was obtained from the tosylate and 2-chlorohexadecan-1-ol from the chloro ester.     

Pharmacokinetic behaviour of R-(+)- and S-(−)-amlodipine after single enantiomer administration

Amlodipine, 3-ethyl 5-methyl-2-[(2-aminoethoxymethyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl-3,5-pyridinedicarboxylate, is a chiral calcium antagonist, currently on the market and in therapeutic use as a racemate. The pharmacokinetic behaviour of R-(+)- and S-(−)-amlodipine after single enantiomer administration to healthy male human volunteers together with comparative administration of the racemic mixture of both enantiomers were studied. Plasma levels were studied as a function of time and assayed using an enantioselective chromatographic method (coupled chiral and achiral HPLC) with on-line solid-phase extraction and UV absorbance detection. The method was validated separately for the R-(+)- and S-(−)-enantiomer, respectively. Results of the study indicate that the pharmacokinetic behaviour of R-(+)- and S-(−)-amlodipine after single enantiomer administration is comparable to that of each enantiomer after administration of the racemate. No racemization occurs in vivo in human plasma after single enantiomer administration.     

Quantitation of o-, m- and p-cresol and deuterated analogs in human urine by gas chromatography with electron capture detection

A gas chromatographic method for the analysis of cresol metabolites of toluene and [²H₈]toluene in urine was developed. Cresol glucuronides and sulfates in urine were hydrolyzed with β-glucuronidase and arylsulfatase. Following extraction with tert.-butyl methyl ether and solvent exchange into benzene, the cresols were derivatized with heptafluorobutyric anhydride to form the heptafluorobutyrate esters. The derivatives were analyzed by gas chromatography with electron capture detection. Chromatographic resolution was achieved between all cresol isomers and their ²H₇ analogs. Calibration ranged from 0.001 to 500 μg/ml. Recoveries were 55–97% and showed no trend with respect to analyte concentration. Within-day precision of analyses of benchmark urine samples had a coefficient of variation of less than 4%. The assay sensitivity was limited by chromatographic background but was sufficient for quantification of the unlabeled cresols in urine from men with only environmental exposure to toluene. Average levels in urine samples from 45 men were 0.023, 0.054 and 37 μg/ml for o-, m- and p-cresol, respectively.     

Separation of Racemic frommeso-2,3-Butanediol

2,3-Butanediol containing less than 3% of themesoform has been obtained from samples containing up to 50% of themesoform. The diacetate was obtained by esterification with acetic anhydride in the presence of traces of sulfuric acid as a catalyst and was then purified. When the diacetate was held at 4°C, crystals of racemic 2,3-butanediol diacetate formed, and these were separated by filtration. The diacetate was then transformed back to 2,3-butanediol by transesterification with methanol in the presence of sodium methylate as a catalyst. The resulting 2,3-butanediol contained less than 3% of themesoform. For an original batch of 2,3-butanediol containing 50%dland 50%meso,this method can isolate up to 70% of the racemate content. If the original 2,3-butanediol contains too muchmesoform, racemic 2,3-butanediol diacetate does not crystallize, but 2,3-butanediol containing up to 60% of themesoform can be enriched up to 70% racemate by distillation.     

The synthesis of -xylo-hexos-4-ulose and some derivatives

D-xylo-Hexos-4-ulose has been synthesised, characterised chromatographically, and methyl α- -xylo-hexopyranosid-4-ulose has been shown to be stable in neutral aqueous solution, contrary to a previous report. Glycosyl phosphate derivatives are also reported.     

Determination of R- and S-3-methyl-2-oxopentanoate enantiomers in human plasma: suitable method for label enrichment analysis

A sensitive method for the determination of S- and R-3-methyl-2-oxopentanoate enantiomers (KMV, (α-keto-β-methylval-erate) in physiological fluids suitable for isotope enrichment analysis is described: after extraction with acid, 2-oxo acids are separated from interfering amino acids by cation-exchange chromatography. Reductive amination of the branched-chain 2-oxo acids by use of - leucine dehydrogenase yields the corresponding -amino acids. -Isoleucine and -alloisoleucine which are formed from S- and R-3-methyl-2-oxopentanoate, respectively, are then quantified by amino acid analysis. The method was used for determination of the R-/S-3-methyl-2-oxopentanoate ratio in plasma of healthy subjects and patients with diabetes mellitus and maple syrup urine disease. Applicability for gas chromatographic-mass spectrometric analysis of ¹³C-label enrichment in plasma S-3-methyl-2-oxopentanoate is demonstrated.     

Synthesis of 2,3-O-(propane-1,2-diyl)- and 2,3-O-(3-hydroxypropane-1,2-diyl)-cyclomaltoheptaose

2¹,3¹-O-(Propane-1,2-diyl)cyclomaltoheptaose has been prepared from 2-O-allylcyclomaltoheptaose by mercuration in trifluoroacetic acid, followed by reduction with sodium borohydride. 2-O-(2,3-Epoxypropyl)cyclomaltoheptaose, prepared from 2-O-allylcyclomaltoheptaose by oxidation with dimethyldioxirane, was converted into 2¹,3¹-O-(3-hydroxypropane-1,2-diyl)cyclomaltoheptaose by treatment with trifluoroacetic acid. Both derivatives containing fused 1,4-dioxane rings are mixtures of stereoisomers, in which the methyl and hydroxymethyl group, respectively, that is linked to this ring, occupies an axial or an equatorial position.     

Synthesis of 4-O- and 6-O-(2′-iodoethyl)-d-glucose

O-Allylation of 1,2,3,6-tetra-O-acetyl- -glucopyranose followed by an ozonation/reduction sequence gave the 4-hydroxyethyl derivative. This hydroxyethyl substituent was also introduced at C-6, starting from 1,2:3,5-bis(O-methylidene)-α- -glucofuranose using an alkylation/reduction sequence. These 4- and 6-O-hydroxyethyl derivatives were then converted to the title compounds by iodination followed by deprotection. Noteworthy is the particular stability of the carbon–iodine bond in these ethers, a prerequisite for their potential use in Single Photon Emitted Computed Tomography medical imaging (SPECT).     

Simultaneous determination of all-trans-, 13-cis-, 9-cis-retinoic acid and their 4-oxo-metabolites in plasma by high-performance liquid chromatography

A gradient reversed-phase high-performance liquid chromatographic technique is described for the easy separation and quantification of some retinoids; all-trans-retinoic acid, 13-cis-retinoic acid, 9-cis-retinoic acid and their corresponding 4-oxometabolites, in plasma. The method involved a diethyl ether-ethyl acetate (50:50, v/v) mixture extraction at pH 7 with acitretin and 13-cis-acitretin as internal standards. A Nova-Pak C₁₈ steel cartridge column was used. The mobile phase was methanol-acetonitrile (65:35, v/v) and 5% tetrahydrofuran (solvent A) and 2% aqueous acetic acid (solvent B) at 1 ml/min. The gradient composition was (only the percentages of solvent B are mentioned): I, 25% solvent B at the time of injection; II, 12% solvent B at 11 min until 30 min; III, 25% solvent B and maintenance of 25% solvent B for 10 min until a new injection. Total time between injections was 40 min. Detection was by absorbance at 350 nm. The precision calculated for plasma concentrations ranging from 2 to 250 ng/ml was better than 15% and the accuracy was less than 12%. The linearity of the method was in the range of 2 to 400 ng/ml of plasma. The limit of quantification was 2 ng/ml for each of the compounds. The HPLC method was applied to plasma specimens collected from animals receiving single dose administrations of all-trans-retinoic acid, 13-cis-retinoic acid and 9-cis-retinoic acid.     

Vergleichend morphologische Untersuchungen zur Jugendentwicklung vonAnser- undBranta-Arten

Zusammenfassung Die Geschwindigkeit der Gewichtszunahme beiAnser indicus ist von der Aufzucht und der Rangstellung eines Gänsekükens in seiner Geschwisterschar abhängig. Mit besserem Futterangebot (Handaufzucht) verkürzt sich die Wachstumsperiode, die Flugfähigkeit setzt früher ein. Das Endgewicht wächst mit der Ranghöhe; die Ranghöhe ist im übrigen nicht von der Höhe des Schlüpfgewichts abhängig (Abb. 2 und 3, Tab. 2).Unter identischen Aufzuchtsbedingungen (Handaufzucht) bleiben bei 8 Arten die artspezifischen Wachstumsperioden erhalten. Die Zunahme an Gewicht ist nicht gleichmäßig, die Zeitspanne größten Zuwachses ist für jede Art festgelegt. Die Lage dieser Zeitspanne in der Wachstumsperiode ist um so früher nach dem Schlüpfen je nördlicher die Art brütet, d. h. je kürzer die Vegetationsperiode ist. Mit der geographischen Breite des Brutgebietes bzw. der Dauer der Vegetationsperiode ist das relative Schlüpfgewicht negativ korreliert.Die Körperlänge (Schnabelspitze mit Schwanzspitze) bei drei Arten wird erst kurz vor dem Erreichen der Adultlänge positiv allometrisch zum Gewicht. Eine negative Allometrie ist besonders ausgeprägt beiBranta leucopsis undAnser a. anser, während das Wachstum der Körperlänge beiAnser indicus isometrisch zum Gewicht verläuft. Adult istBranta leucopsis die relativ kürzeste Gans, bezogen auf das Gewicht.Die Küken vonBranta leucopsis schlüpfen mit dem prozentual längsten Kopf und dem längsten Schnabel, bezogen jeweils auf die Adultlängen. Entsprechend bleibt das Wachstum dieser Teile (Abb. 8) negativ allometrisch bezogen auf die Körperlänge. Das Verhältnis Kopflänge zu Kopfbreite bleibt konstant während der Entwicklung. Die Läufe zeigen bei den Gänsen auch nach dem Schlüpfen noch eine positive Wachstumstendenz bezogen auf die Körperlänge. Sie erreichen vorzeitig die Adultlänge. Das vorgezogene Wachstum der Läufe und die, verglichen mit Ruder- und Tauchenten relative Reduktion der Zehen (resp. Schwimmhäute), werden als Anpassung an das Weiden an Land gedeutet.Das Flügelwachstum setzt bei allen drei Arten spät ein. Die größte relative Differenz zwischen Flügel und Lauf liegt um den 10. Tag nach dem Schlüpfen, nicht wie beim Huhn zum Zeitpunkt des Schlüpfens. Die relativ längsten Flügel (bezogen auf das Gewicht) besitzt die Streifengans. Mit den Flügelproportionen und der Größe der Flächenbelastung kann die Zugstrecke korreliert werden. Je länger sie ist, desto niedriger ist die Flächenbelastung und desto relativ länger ist der Unterarm.Auch der jeweilige Beginn der Mauser in das Jugendgefieder läßt sich zur geographischen Breite des Brutgebietes bzw. der Vegetationsperiode in Beziehung setzen: Je nördlicher die Art brütet, um so früher setzt sie ein (Tab. 4 und 5). Die Dauer der Gefiederentwicklung verkürzt sich entsprechend der Dauer der Vegetationsperiode, so daß bei der Streifengans das Gefiederwachstum beschleunigt abläuft.

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Comparative morphological studies on the development of youngAnser- andBranta-species

Summary 1. Development of weight inAnser indicus: The increase of the goslings' weight inAnser indicus is affected by rearing conditions and by the position of the gosling in the rank order of its siblings. A ready supply of rich food (e.g. at raising by hand) shortens the period of growth and the time until the gosling is able to fly if compared to raising by the parents under natural conditions.The final weight of the gosling is positively correlated with its position in the rank order of its siblings; this position, however, is independent of the weight at hatching.2. Development of weight inAnser a. anser, Anser a. albifrons, Anser brachyrhynchus, Anser c. caerulescens, Anser cygnoides, Anser indicus, Branta c. canadensis and Branta leucopsis: Under identical rearing conditions for all species the species specific periods of development are maintained. Rate of growth varies during development, and the time of maximum growth after hatching seems to be species specific. It corresponds with the latitude of the breeding areas of the species. In northern species the maximum weight increase is earlier in the period of development than in southern species. The latitude on the other hand corresponds with the duration of the vegetation period: a high latitude results in a short period of vegetation. The period of vegetation can be correlated with the relative weight of the newly hatched goslings: the shorter the period the higher the weight.The data ofAnser indicus can be interpreted with respect to the short vegetation period in the high regions of their breeding places in Central Asia.3. Increase of body length and relative growth of parts of the body inAnser a. anser, Anser indicus andBranta leucopsis: A short time before reaching the adult stage the body length (as measured from peak of bill to end of tail) shows positive allometric growth with respect to weight. In earlier stages a strong negative allometric growth is found inBranta leucopsis andAnser a. anser, while inAnser indicus the growth is isometric. Branta leucopsis has the smallest proportion of length to body weight of the adults and is the smallest by weight of the 3 species at hatching. However, proportional to adult length it has the longest bill and head at hatching. Correspondingly these parts show negative allometric growth as compared to body length. The proportion of head length to head width is constant during development.In all three species the legs grow positive allometric related to body length and the adult stage is reached before other development is finished. This advanced growth of the legs as well as the reduction of the length of toes as compared to the data ofOxyura andAythya is interpreted as an adaption to feeding. The growth of wings starts late in all three species investigated. The largest difference between length of wings and legs was observed at the 10th day after hatching, in chickens it is found after hatching.The wings are longest inAnser indicus relative to weight. Wing proportion and wing load (in g/cm²) can be correlated with flight distance to wintering places. A small wingload and a relatively long forearm ist found in species which migrate over long distances. The start of moulting into juvenile plumage corresponds with the latitude of the breeding area. Northern species show an early beginning of moult after hatching. The duration of plumage growth is relatively short if vegetation period is short. Thus inAnser indicus the plumage growth appears to be accelerated as compared to species breeding in areas with longer periods of vegetation.