Aluminium in tea—concentrations, speciation and bioavailability

Tea (Camellia sinensis) is one of a few plants accumulating aluminium (Al), making tea a major source of dietary Al intake. This paper reviews published studies on the concentrations, speciation and bioavailability of Al in tea. With very few exceptions, the total concentration of Al in tea infusions is in the range 1-6 mg l⁻¹. Probably more than 90% of this Al is bound to organic matter, but the nature of the organic species is unclear. Three studies using size exclusion chromatography provide evidence for Al species in the molecular mass (MM) range 4000-8500 Da, probably polyphenolic complexes. Two ultrafiltration studies indicate the presence of Al species with MMs above 10,000. The relative amount of the different organic Al species in tea infusions is unclear, and even the identity of any of these has not been demonstrated with certainty. A possible exception is Al trioxalate, which may be an important species based on evidence from two ²⁷Al-NMR studies. It seems fairly well established that drinking tea leads to measurable, but moderate increases in urinary Al excretion. However, the Al present in tea does not seem to be much more bioavailable than that from other dietary sources. Even so, it cannot be dismissed that tea infusions may contain particularly bioavailable and neurotoxic compounds such as Al maltolate, but this is at present speculative.     

Effect of Concentration of Structurally-Different Carboxylic Acids on Growth and Aggregation of Calcium Oxalate in Gel Systems

The effect of concentration of structurally-different carboxylic acids such as ethylene diamine tetraacetic acid （H4edta）, citric acid （H3cit）, tartaric acid （H2tart）, and acetic acid （HOAc） on growth and aggregation of calcium oxalate （CaOxa） in gel systems was comparatively investigated. H2tart and H3cit could change the morphology of cal- cium oxalate monohydrate （COM） and induce the formation of calcium oxalate dihydrate （COD）. H4edta could induce the formation of COD at a lower concentration of 0.33 mmol/L and have the strongest ability to inhibit aggregation of COM. HOAc inhibited COM aggregation only at a higher concentration than 500 mmol/L. With increasing the number of carboxylic groups in an acid or increasing the concentration of carboxylic acid, the capacity of this acid to induce COD formation and to inhibit growth and aggregation of COM crystals increased. That is, this capacity followed the order： H4edta〉H3cit〉H2tart〉 〉HOAc. The result in this work suggested that the presence of H3cit and H2tart in urine played a role in the natural defense against stone formation.     

Recent advancement and development of chitin and chitosan-based nanocomposite for drug delivery: Critical approach to clinical research

This review depicts the exposure of chitin and chitosan base multifunctional nanomaterial composites for promising applications in field of biomedical science structure, synthesis as well as potential application from a colossal angle. We elaborated critically each of the chitin and chitosan base nanomaterial with its potential application toward biomedical science. For different biomedical applications it use in form of hydrogels, microsphere, nanoparticles, aerogels, microsphere and in form of scaffold. Due to this it had been blended with different polymer such as starch, cellulose, alginate, lipid, hyaluronic acid, polyvinyl alcohol and caboxymethyl cellulose. In this review article, a comprehensive overview of combination of chitin and chitosan base nanomaterial with natural as well as synthetic polymers and their biomedical applications in biomedical field involving drug delivery system all the technical scientific issues have been addressed; highlighting the recent advancements.     

Simulation of calcium oxalate stone in vitro

Urolithiasis constitutes a serious health problem that affects a significant section of mankind. Between 3% and 14% of the population, depending on the geographical region, suffer from this illness[1]. For example, the incidence of urolithiasis in Florida in the United States of America was 15.7 in 100000 people and increased to 20.8 in 1996. Urolithiasis remains a major medical prob-lem in China, especially in Guangdong Province. A survey in 1997 in Shenzhen City, the most southern city i…     

Bioaccumulation of Antimony by Chlorella vulgaris and the Association Mode of Antimony in the Cell

The bioaccumulation and excretion of antimony by the freshwater alga Chlorella vulgaris , which had been isolated from an arsenic-polluted environment, are described. When this alga was cultured in a medium containing 50 μg cm⁻³ of antimony(III) for 14 days, it was found that Chlorella vulgaris bioaccumulated antimony at concentrations up to 12 000 μg Sb g⁻¹ dry wt after six days' incubation. The antimony concentration in Chlorella vulgaris decreased from 2570 to 1610 μg Sb g⁻¹ dry wt after the cells were transferred to an antimony-free medium. We found that the excreted antimony consists of 40% antimony(V) and 60% antimony(III). This means that the highly toxic antimony(III) was converted to the less toxic antimony (V) by the living organism. Antimony accumulated in living Chlorella vulgaris cells was solvent-fractionated with chloroform/methanol (2:1), and the extract residue was fractionated with 1% sodium dodecyl sulfate (SDS). Gel-filtration chromatography of the solubilized part showed that antimony was combined with proteins whose molecular weight was around 4×10⁴ in the antimony-accumulated living cells. © 1997 by John Wiley & Sons, Ltd.     

海藻硫酸多糖抑制草酸钙结石形成的化学模拟

用体外模拟方法研究了从海藻异枝麒麟菜中提取的硫酸多糖(ESPS)对尿结石患者尿液中草酸钙晶体生长的影响. ESPS不但诱导与尿路细胞膜粘附力较弱的二水草酸钙晶体形成, 而且抑制一水草酸钙的生长和聚集, 归因于一水草酸钙的富钙(101)晶面与聚阴离子ESPS之间的静电相互作用. 上述结果表明, ESPS是一种抑制草酸钙结石的潜在绿色药物.     

Dictamnine Inhibits the Adhesion to and Invasion of Uropathogenic Escherichia Coli (UPEC) to Urothelial Cells

Uropathogenic Escherichia coli (UPEC) is the most common pathogenic bacteria associated with urinary tract infection (UTI). UPEC can cause UTI by adhering to and invading uroepithelial cells. Fimbriae is the most important virulence factor of UPEC, and a potentially promising target in developing novel antibacterial treatments. In this study, the antibacterial properties and effects of the compound dictamnine, extracted from the traditional Chinese medicine Cortex Dictamni, on the bacterial morphology, cell adhesion, and invasion of UPEC were studied. Dictamnine exhibited no obvious antibacterial activity against UPEC, but significantly impeded the ability of UPEC to adhere to and invade uroepithelial cells. RT-qPCR analysis showed that treatment downregulated the expression of type 1 fimbriae, P fimbriae, and curli fimbriae adhesion genes, and also downregulated adhesion-related receptor genes of uroepithelial cells. Transmission electron microscopy showed that dictamnine destroyed the structure of the fimbriae and the surface of the bacteria became smooth. These results suggest that dictamnine may help to prevent UTI by simultaneously targeting UPEC fimbriae and urothelial adhesin receptors, and may have a potential use as a new anti-UPEC drug.     

Growth of calcium oxalate monohydrate on uric acid crystals at sustained supersaturation

The effect of uric acid seeds on calcium oxalate formation was studied at pH 4.50 and 37 °C using a system providing constant supersaturation with respect to calcium oxalate and saturated in uric acid. In all cases the only solid‐phase forming was identified as calcium oxalate monohydrate (COM). Kinetic analysis of the initial rates showed that they were proportional with the relative supersaturation with respect to calcium oxalate monohydrate. The linear dependence of the rate of precipitation of COM on uric acid suggested that growth is mediated through a surface diffusion controlled mechanism. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The effect of cellular energetics on foreign protein production

Escherichia coli strain F-122 was used to determine if there are additional physiological effects, other than decreasing energetic efficiency accompanied by the excretion of the acetate, on foreign protein production. This organism was the host for expressing HIV₅₈₂-β-galactosidase fusion protein under the control of thetrp promoter, with ampicillin resistance. By comparing parallel batch cultures with and without acetate addition, it was found that the presence of acetate in the media did not influence β-galactosidase activity. In these experiments, it appears that the low protein productivity often observed during acetate formation is the result of inefficient cell metabolism, rather than acetate acting as a specific inhibitor of protein production.     

过饱和度、反应物化学计量比及离子强度对草酸钙晶体生长的影响

肾结石是一种普遍的疾病,全球的发病率约为10%,且其复发率高。2003年欧洲的一项统计表明,尿石患者第一次复发率为40%[1]。草酸钙(CaOxa)是肾结石的主要成分,其体外模拟引起了人们广泛的关注[2,3]。然而,普通溶液体系的模拟环境不能充分反映尿石的形成环境,用类似细胞膜的有序分