A simplified spectrophotometric method for routine analysis of saccharin in commercial noncaloric sweeteners     

Los Weinert P  Pezza HR  de Oliveira JE  Pezza L 《Journal of agricultural and food chemistry》2004,52(26):7788-7792

A simple, rapid, and sensitive spectrophotometric method for routine analysis of saccharin in commercial noncaloric sweeteners is proposed. This method is based on the reaction of saccharin with tetrachloro-p-benzoquinone (p-chloranil) accelerated by hydrogen peroxide and conducted in an ethanol:acetone (4:1) medium, producing a violet-red compound (lambda(max) = 550 nm). Beer's law is obeyed in a concentration range of 2.05 x 10(-4) to 3.00 x 10(-3) M with an excellent correlation coefficient (r = 0.9998). The detection limit was 1.55 x 10(-5) M, and the effect of interferences on the spectrophotometric measurements was evaluated. The proposed procedure was applied successfully to the determination of saccharin in noncaloric sweeteners. Recoveries were within 99.2-104.3% with standard deviations ranging from to 0.5-1.6%. Results of the proposed method compare very favorably with those given by the high-performance liquid chromatography method recommended by the Food and Drug Administration.  相似文献   

Effect of solid residues from the cellulose industry on plant growth     

Miguel Jordan  Eduardo Rodriguez 《植物养料与土壤学杂志》2004,167(3):351-356

An alternative use of solid organic and inorganic residues as fertilizers from a Kraft pulp industry was studied. Residues of inorganic nature, such as ashes, fly‐ashes, dregs, grits, as well those rich in organic matter, primary sludge and brown stock rejects, were examined for plant growth enhancement. These residues, all alkaline in nature, used in different concentrations together with soil, bark, organic soil or mixed with a nutrient solution, were tested on the growth of Monterey pine (Pinus radiata), Eucalyptus globulus, rice (Oryza sativa. cv. ‘Diamante’), and duckweed (Lemna minor) under greenhouse and in‐vitro conditions, respectively. Responses varied according to plant species, type, and waste content in combination with substrate. For Monterey pine, substrates including ash, fly‐ash, and dregs promoted growth; in Eucalyptus seedlings dregs and fly‐ash were also beneficial. Primary sludge and ash were favorable for rice growth. Duckweed increased frond number and plant biomass when grown in water containing fly‐ash and primary sludge extracts, combined with nutrient salts.  相似文献   

Profiling glucosinolates, flavonoids, alkaloids, and other secondary metabolites in tissues of Azima tetracantha L. (Salvadoraceae)     

Bennett RN  Mellon FA  Rosa EA  Perkins L  Kroon PA 《Journal of agricultural and food chemistry》2004,52(19):5856-5862

Azima tetracantha L. (needle bush; bee sting bush; Salvadoraceae) is used as a food and for various herbal medicines in Africa, India, and Madagascar, but there is very little information on the secondary metabolites in this species. High concentrations of N-methoxy-3-indolylmethyl-glucosinolate, a common glucosinolate of Brassica crops such as Brussels sprouts and broccoli, were found in the roots and seeds of A. tetracantha. Lower concentrations were detected in the stems and young leaves. The roots also contained another indole glucosinolate that was provisionally identified, from MS data and comparison with indole glucosinolate standards, as N-hydroxy-3-indolymethyl-glucosinolate. The roots, stems, and leaves contained neoascorbigen (the condensation product of N-methoxy-indole-3-carbinol and ascorbic acid). The seeds of A. tetracantha contained a complex mixture of 26 flavonoids predominantly as glycosides and acyl-glycosides, with traces of aglycones. The core aglycones of these flavonoids were identified as quercetin, isorhamnetin (3'-O-methylquercetin), rhamnetin (7-O-methylquercetin), and rhamnazin (7, 3'-di-O-methylquercetin). No flavonoids or anthocyanins were detected in other tissues, and procyanidins were undetectable. The dimeric piperidine alkaloids azimine, azcarpine, and carpaine were found in all tissues of A. tetracantha.  相似文献   

Species diversity and habitat fragmentation: frogs in a tropical montane landscape in Mexico     

Eduardo Pineda  Gonzalo Halffter 《Biological conservation》2004,117(5):499-508

We evaluate the alpha (within patch species richness), beta (spatial turnover among patches) and gamma (landscape) diversity of frogs in a tropical montane cloud forest (TMCF) in central Veracruz, Mexico in order to assess (1) the influence of forest fragmentation on frog assemblages, (2) the importance to diversity of the various elements of the landscape matrix, including the shaded coffee plantations and cattle pastures that surround TMCF and (3) to identify the frog guilds most affected by habitat transformation. We sampled ten sites between May 1998 and November 2000: five TMCF fragments and five anthropogenic habitats. For the entire landscape, we registered 21 species belonging to six families. 100% of these were found in the TMCF fragments and 62% in the surrounding mosaic of anthropogenic habitats. Gamma diversity (γ) is determined to a greater extent by species exchange (β) than by local species richness (α). Elevational variation, the degree of conservation of the vegetation canopy and fragment size appear to determine the species diversity of this landscape. Large species, terrestrial species, those whose eggs develop outside water, and those whose larvae develop in the water seemed to be most affected by habitat transformation. On its own, even the largest and most species-rich cloud forest fragment is not capable of preserving the current anuran diversity. Neither are the shaded coffee plantations that are interspersed among and link the patches of TMCF. However together they form a diverse system of habitats crucial to species conservation in this landscape.  相似文献   

Tear urea nitrogen and creatinine levels in horse and their correlation with serum values     

Zapata GL  Britos RM  Pintos ME  Dreizzen E  Lausada NB  Arauz S 《Veterinary ophthalmology》2005,8(3):207-209

The objective of this paper was to determine the physiological values of urea nitrogen and creatinine in tears, and to compare the results with those obtained from serum. Thirty healthy thoroughbred horses were included in the study. Tear fluid samples were obtained using a glass capillary tube placed in lower conjunctival cul-de-sac. Blood samples were taken from the jugular vein. Tear and serum urea nitrogen and creatinine levels were quantitatively analyzed by an enzymatic colorimetric method. Urea nitrogen values were 4.22+/-1.84 mmol/l in tears and 4.44+/-1.78 mmol/l in serum, whereas creatinine values in tears were 14.14+/-7.74 micromol/l and in serum 147.63+/-12.17 micromol/l. Statistical analysis confirmed a significant correlation between serum and tear urea levels (P<0001). However, there was no significant correlation between blood and tear creatinine values. Mean value of creatinine obtained from tears was 9.6% of the mean value from serum. Urea nitrogen and creatinine levels can be measured in tears. A significant correlation was found between serum and tears urea levels. This finding may permit development of a new alternative laboratory diagnosis of uremia based on the content of urea in tears.  相似文献   

Cervical diskospondylitis in a calf: clinical, radiographic, and necroscopy findings          下载免费PDF全文

Paiva Della Libera AM  Leal ML  Gregory L  Rodrigues da Silva DY  Unruh SM  Birgel Júnior EH  Benesi FJ 《The Canadian veterinary journal. La revue veterinaire canadienne》2004,45(8):700-701

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Impaired control of IRES-mediated translation in X-linked dyskeratosis congenita     

Yoon A  Peng G  Brandenburger Y  Brandenburg Y  Zollo O  Xu W  Rego E  Ruggero D 《Science (New York, N.Y.)》2006,312(5775):902-906

The DKC1 gene encodes a pseudouridine synthase that modifies ribosomal RNA (rRNA). DKC1 is mutated in people with X-linked dyskeratosis congenita (X-DC), a disease characterized by bone marrow failure, skin abnormalities, and increased susceptibility to cancer. How alterations in ribosome modification might lead to cancer and other features of the disease remains unknown. Using an unbiased proteomics strategy, we discovered a specific defect in IRES (internal ribosome entry site)-dependent translation in Dkc1(m) mice and in cells from X-DC patients. This defect results in impaired translation of messenger RNAs containing IRES elements, including those encoding the tumor suppressor p27(Kip1) and the antiapoptotic factors Bcl-xL and XIAP (X-linked Inhibitor of Apoptosis Protein). Moreover, Dkc1(m) ribosomes were unable to direct translation from IRES elements present in viral messenger RNAs. These findings reveal a potential mechanism by which defective ribosome activity leads to disease and cancer.  相似文献   

Freezing as a path to build complex composites   总被引：1，自引：0，他引：1  

Deville S  Saiz E  Nalla RK  Tomsia AP 《Science (New York, N.Y.)》2006,311(5760):515-518

Materials that are strong, ultralightweight, and tough are in demand for a range of applications, requiring architectures and components carefully designed from the micrometer down to the nanometer scale. Nacre, a structure found in many molluscan shells, and bone are frequently used as examples for how nature achieves this through hybrid organic-inorganic composites. Unfortunately, it has proven extremely difficult to transcribe nacre-like clever designs into synthetic materials, partly because their intricate structures need to be replicated at several length scales. We demonstrate how the physics of ice formation can be used to develop sophisticated porous and layered-hybrid materials, including artificial bone, ceramic-metal composites, and porous scaffolds for osseous tissue regeneration with strengths up to four times higher than those of materials currently used for implantation.  相似文献   

Ontogenic profiling of glucosinolates, flavonoids, and other secondary metabolites in Eruca sativa (salad rocket), Diplotaxis erucoides (wall rocket), Diplotaxis tenuifolia (wild rocket), and Bunias orientalis (Turkish rocket)     

Bennett RN  Rosa EA  Mellon FA  Kroon PA 《Journal of agricultural and food chemistry》2006,54(11):4005-4015

As an influence of the Mediterranean diet, rocket species such as Eruca sativa L., Diplotaxis species, and Bunias orientalis L. are eaten all over the world at different ontogenic stages in salads and soups. They are all species within the plant order Capparales (glucosinolate-containing species), and all are from the family Brassicaceae. Predominantly, the leaves of these species are eaten raw or cooked, although Eruca flowers are also consumed. There is considerable potential with raw plant material for a higher exposure to bioactive phytochemicals such as glucosinolates, their hydrolysis products, and also phenolics, flavonoids, and vitamins such as vitamin C. These compounds are susceptible to ontogenic variation, and the few published studies that have addressed this topic have been inconsistent. Thus, an ontogenic study was performed and all samples were analyzed using a previously developed robust liquid chromatography/mass spectrometry method for the identification and quantification of the major phytochemicals in all tissues of the rocket species. Seeds and roots of both Eruca and Diplotaxis contained predominantly 4-methylthiobutylglucosinolate. Leaves of Eruca and Diplotaxis contained high amounts of 4-mercaptobutylglucosinolate with lower levels of 4-methylthiobutlyglucosinolate and 4-methylsulfinylbutylglucosinolate. Flowers of Eruca and Diplotaxiscontained predominantly 4-methylsulfinylbutyl-glucosinolate. In addition, roots of both Diplotaxisspecies contained 4-hydroxybenzylglucosinolate but 4-hydroxybenzylglucosinolate was absent from roots of Eruca. Seeds and seedlings of all Eruca contained N-heterocyclic compounds but no sinapine, whereas Diplotaxis contained sinapine but not the N-heterocycles. In all tissues of B. orientalis, 4-hydroxybenzylglucosinolate and 4-methylsulfinyl-3-butenylglucosinolate were predominant. All rocket tissues, except roots, contained significant levels of polyglycosylated flavonoids, with/without hydroxycinnamoyl acylation. The core aglycones were kaempferol, quercetin, and isorhamnetin. The exception was B. orientalis, which had a negligible seed flavonoid content as compared with the other species. Anthocyanins were only detected in Eruca flowers and consisted of a complex pattern of at least 16 different anthocyanins.  相似文献   

Screening of tropical fruit volatile compounds using solid-phase microextraction (SPME) fibers and internally cooled SPME fiber     

Carasek E  Pawliszyn J 《Journal of agricultural and food chemistry》2006,54(23):8688-8696

In this study, the optimization and comparison of an internally cooled fiber [cold fiber with polydimethylsiloxane (PDMS) loading] and several commercial solid-phase microextraction (SPME) fibers for the extraction of volatile compounds from tropical fruits were performed. Automated headspace solid-phase microextraction (HS-SPME) using commercial fibers and an internally cooled SPME fiber device coupled to gas chromatography-mass spectrometry (GC-MS) was used to identify the volatile compounds of five tropical fruits. Pulps of yellow passion fruit (Passiflora edulis), cashew (Anacardium occidentale), tamarind (Tamarindus indica L.), acerola (Malphigia glabra L.), and guava (Psidium guajava L.) were sampled. The extraction conditions were optimized using two experimental designs (full factorial design and Doehlert matrix) to analyze the main and secondary effects. The volatile compounds tentatively identified included alcohols, esters, carbonyl compounds, and terpernes. It was found that the cold fiber was the most appropriate fiber for the purpose of extracting volatile compounds from the five fruit pulps studied.  相似文献