酒石酸及其盐抑制泌尿系结石的化学基础

本文探讨了酒石酸及其盐对泌尿系结石形成、抑制和治疗的化学基础,重点讨论了其与钙离子的螯合,诱导二水草酸钙和三水草酸钙形成、减少晶体滞留,影响CaOxa晶体的晶面与形貌,抑制尿石矿物的成核、生长和聚集,调节新陈代谢、减小尿石形成的几率,并讨论了抗衡阳离子对其抑制能力的影响。     

Estimation of the porous structure of active carbons

Active carbons from apricot, plum, peach, and grape stones were prepared. The analysis of adsorption isotherms of benzene vapor showed that the active carbons obtained from fruit stones have highly homogeneous microporous structures withW ₀ 0.30 cm³ g^–1,E ₀ 24.5 kJ mol^–1, andx ₀ 0.42 nm, and they contain ultramicropores along with micropores.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1934–1936, October, 1995.This study was financially supported by the Russian Foundation for Basic Research (Project No. 94-03-09550).     

Plants Used in Mexican Traditional Medicine for the Management of Urolithiasis: A Review of Preclinical Evidence,Bioactive Compounds,and Molecular Mechanisms

Urolithiasis (UL) involves the formation of stones in different parts of the urinary tract. UL is a health problem, and its prevalence has increased considerably in developing countries. Several regions use plants in traditional medicine as an alternative in the treatment or prevention of UL. Mexico has known about the role of traditional medicine in the management of urinary stones. Mexican traditional medicine uses plants such as Argemone mexicana L., Berberis trifoliata Hartw. ex Lindl., Costus mexicanus Liebm, Chenopodium album L., Ammi visnaga (L.) Lam., Eysenhardtia polystachya (Ortega) Sarg., Selaginella lepidophylla (Hook. & Grev.) Spring, and Taraxacum officinale L. These plants contain different bioactive compounds, including polyphenols, flavonoids, phytosterols, saponins, furanochromones, alkaloids, and terpenoids, which could be effective in preventing the process of stone formation. Evidence suggests that their beneficial effects might be associated with litholytic, antispasmodic, and diuretic activities, as well as an inhibitory effect on crystallization, nucleation, and aggregation of crystals. The molecular mechanisms involving these effects could be related to antioxidant, anti-inflammatory, and antimicrobial properties. Thus, the review aims to summarize the preclinical evidence, bioactive compounds, and molecular mechanisms of the plants used in Mexican traditional medicine for the management of UL.     

Thermal analysis of renal stones

The chemical composition of 200 renal stones, collected from Taxila, Rawalpindi and Islamabad regions in Pakistan, was determined by thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The thermal curves show weight losses at various temperatures indicating dehydration and decomposition phenomena of renal stones. Results were compared with qualitative data obtained by IR analysis which confirmed the chemical composition of various stones in the solid state. The thermal curves helped in the differentiation of various kinds of water held by stones and their chemical composition was obtained by weight loss during pyrolysis. It was found that 26.5% of the stones were pure whewellite, 3% weddellite, 13% uric acid anhydrous, 7.5% struvite, 2.5% ammonium acid urate, 0.5% cystine and 47% stones had mixed composition. In the mixed state the most frequent combinations were those of calcium oxalate with uric acid (14.5%) and with phosphates (27.5%).

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Zusammenfassung Mittels TG und DTA wurde die chemische Zusammensetzung von 200 Nierensteinen untersucht, die in den Gebieten Taxila, Rawalpindi und Islamabad in Indien gesammelt wurden. Die Thermogramme zeigen Masseverluste bei verschiedenen Temperaturen, die auf Dehydratation und Zersetzung der Nierensteine hinweisen. Die Ergebnisse wurden mit den qualitativen Resultaten aus der IR-Analyse verglichen, welche die chemische Zusammensetzung der verschiedenen Steine im festen Zustand bekräftigte. Die Thermogramme halfen bei der Unterscheidung von verschieden gebundenem Wasser, ihre chemische Zusammensetzung wurde durch Gewichtsverlust bei der Pyrolyse bestimmt. Man fand, daß 26.5 % der Steine aus reinem Whewellit bestanden, 3 % aus Weddellit, 13 % aus anhydrierter Harnsäure, 7.5 % aus Struvit, 2.5 % aus Ammmoniumhydrogenurat, 0.5 % aus Cystin und 47 % der Steine hatten eine gemischte Zusammensetzung. Die häufigsten Kombinationen der Mischzusammensetzungen waren Calciumoxalat mit Harnsäure (14.5 %) und mit Phosphaten (27.5 %).

     

Thermal, UV, FTIR, and XRD studies of urinary stones

Various crystals are seen in human urine. Oxalate, Phosphate, Uric acid, and Urate crystals are generally seen in urinary calculi. Calcium stones are most common, comprising 75 % of all urinary calculi. They may be pure calcium oxalate or calcium phosphate or a mixture of both. Many stones are not homogeneous. Low calcium intake increases the intestinal absorption of calcium, thus decreasing the amount of calcium available in the intestinal tract to form insoluble complexes with Oxalate. Consequently, a higher amount of oxalate is available for intestinal absorption and as a result, urinary oxalate excretion increases. Mineral water consumption did not reduce urinary oxalate excretion. High urinary excretion and concentration of magnesium decrease both the nucleation and growth rates of calcium oxalate crystals in urine, because of the higher solubility of magnesium oxalate compared with calcium oxalate. Analytical results show calcium oxalate to be one of the major inorganic components of renal stones and found to be present in almost all kidney and bladder stones. About 39.5 % of the total composition of the calculi is found to contain purely calcium oxalate and also hydroxyl apatite. The ten samples are a mixture of calcium oxalate and phosphate stones. Four samples are calcium oxalate as major composition and the remaining are calcium phosphate as major composition. These kidney stones are taken photographically and size of the stone are measured using optical microscopy. These qualitative analyses are also confirmed by UV, FTIR, DSC, and XRD analysis.     

An Approach to the Use of Glycol Alkoxysilane–Polysaccharide Hybrids in the Conservation of Historical Building Stones

Stone consolidants have been widely used to protect historical monuments. Consolidants and hydrophobic formulations based on the use of tetraethoxysilane (TEOS) and alkylalkoxysilanes as precursors have been widely applied, despite their lack of solubility in water and requirement to be applied in organic media. In the search for a “greener” alternative based on silicon that has potential use in this field, the use of tetrakis(2-hydroxyethyl)silane (THEOS) and tris(2-hydroxyethyl)methyl silane (MeTHEOS) as precursors, due their high water solubility and stability, is proposed in this paper. It is already known that THEOS and MeTHEOS possess remarkable compatibility with different natural polysaccharides. The investigated approach uses the water-soluble silanes THEOS–chitosan and MeTHEOS–chitosan as a basis for obtaining hybrid consolidants and hydrophobic formulations for the conservation of siliceous and calcareous stones. In the case of calcareous systems, their incompatibility with alkoxysilanes is known and is expected to be solved by the developed hybrid consolidant. Their application in the conservation of building stones from historical and archeological sites from Guanajuato, México was studied. The evaluation of the consolidant and hydrophobic formulation treatment was mainly conducted by determining the mechanical properties and contact angle measurements with satisfactory results in terms of the performance and compatibility with the studied stones.     

不同模拟体系中草酸钙结晶的比较研究

泌尿系结石是一种世界范围内的常见病及多发病 ,如深圳市的尿结石患病率高达 4.87%[1] ,其发病率呈上升趋势 .泌尿系结石在手术后复发率高 ,尤其是对结石的预防 ,目前尚无十分理想的方法 ,至今其形成机制未完全阐明 ,80 %以上的尿结石患者病因不清 [2 ] .草酸钙 (Ca C2 O4 )是泌尿系结石的主要成分 .体内 Ca C2 O4 结石的形成与热力学 (过饱和度 )和动力学 (成核、生长和聚集 )因素相关 .虽然在尿液中发现有二水草酸钙 (COD)晶体 ,但是热力学稳定的一水草酸钙 (COM)是尿石中最普遍的晶型[3 ] .在大多数的 Ca C2 O4 结石中 ,COM的发…     

HKC细胞损伤前后对草酸钙晶体吞噬能力的差异

采用人类肾脏近端小管上皮细胞系(HKC)建立氧化性损伤模型,研究损伤前后HKC调控草酸钙(CaOxa)结晶的差异。采用CCK-8法检测HKC的细胞活性;利用激光共聚焦显微镜观察HKC损伤后表达的晶体粘附分子骨桥蛋白(OPN);采用倒置显微镜观察HKC的形态变化;采用扫描电子显微镜(SEM)观察HKC微结构及其诱导的晶体;采用X射线衍射分析(XRD)表征晶体的组分。在CaOxa过饱和溶液中,正常HKC主要诱导形成二水草酸钙(COD)晶体,而损伤HKC则同时诱导了COD和一水草酸钙(COM)晶体。正常HKC对COD晶体有较强的吞噬能力,而损伤HKC的这种能力较弱;HKC损伤后表达OPN,促进CaOxa晶体的成核和聚集,从而增加了肾结石形成的危险性。     

Analysis of urinary stone constituents using powder X-ray diffraction and FT-IR

Constituents of urinary stones obtained from various patients from western part of India, which is a highly urinary stone disease-prone area, have been analysed. Eight stones from four patients were collected through urologists and have been analysed using powder X-ray diffraction and FT-IR. Thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) image of selected samples were also carried out. The analysis revealed that calcium oxalate monohydrate, which is also known as whewellite, is the common constituent of all of the stones, particularly at the initial stage of stone formation. However, multi phases viz. whewellite phase, and hydroxyl and carbonate apatite phases are also detected in the case of third and fourth patients, from where multiple stones were obtained. Interestingly, in these mixed phase stones the concentration of whewellite decreases with increasing the concentration of apatite phases. Thermal behaviour of the whewellite phase was studied by TGA and variable temperature XRD analysis. Morphology of the whewellite and apatite phases, examined by SEM image, has also been reported.     

Preparation and characterization of activated carbon from date stones by physical activation with steam

Activated carbons are produced from wastes of Algerian date stones by pyrolysis and physical activation in the presence of water vapor into a heated fixed-bed reactor. The effect of pyrolysis temperature and activation hold time on textural and chemical surface properties of raw date stones and carbon materials produced are studied. As expected, the percentage yield decreases with increase of activation temperature and hold time. The characterization of carbon materials is performed by scanning electron microscopy (SEM). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption (BET). Results show the presence of cellulose and hemicellulose in the raw material, and the predominance of carbon and graphite after pyrolysis. Different oxygen-containing functional groups are found in the raw material while aromatic structures are developed after pyrolysis and activation. The best specific surface area (635 m² g⁻¹) and microporous volume (0.716 cm³ g⁻¹) are obtained when the date stones are grinded, pyrolysed at 700 °C under a 100 cm³ min⁻¹ nitrogen flow and then activated under water vapor at 700 °C for 6 h.     

Proficiency testing on the analytical control of precious metal production

Our experience of executing proficiency testing programs on the analysis of precious metals and precious metal bearing materials is summarized. Six proficiency testing programs of the ”distributed sample testing” type were carried out using samples essentially distinct from each other: (I) certified samples of fine gold and fine silver, and (II) recoverable raw (scrap and catalyst waste) containing precious metals of unknown contents. The test results were assessed using the London Bullion Market Association (LBMA) rules and by Z-criteria using the ISO/IEC Guide 43 scale. Satisfactory results were presented by all participants for the analysis of certified samples of fine gold and fine silver. The results of catalyst waste analysis agreed rather well, whereas the scrap analysis revealed an essential discrepancy in the data for some samples. The reasons for such discrepancies are discussed. Received: 9 June 2000 Accepted: 21 November 2000     

An in situ atomic force microscopy study of uric acid crystal growth

Kidney stones are heterogeneous polycrystalline aggregates that can consist of several different building blocks. A significant number of human stones contain uric acid crystals as a crystalline component, though the molecular-level growth of this important biomaterial has not been previously well-characterized. In the present study, in situ atomic force microscopy (AFM) is used to investigate the real-time growth on the (100) surface of uric acid (UA) single crystals as a function of fundamental solution parameters. Layer-by-layer growth on UA (100) was found to be initiated at screw dislocation sites and to proceed via highly anisotropic rates which depend on the crystallographic direction. The smallest b-steps exhibited minimum heights corresponding to two molecular layers, while fast-moving c-steps more commonly showed monolayer heights. Growth kinetics measured under a range of flow rates, supersaturation levels, and pH values reveal linear trends in the growth kinetics, with faster growth attained in solutions with higher supersaturation and/or pH. The calculated kinetic parameters for UA growth derived from these experiments are in good agreement with the values reported for other crystal systems.     

点石成金——人造钻石的真相

"A diamond is forever", diamond is not only seen as a kind of precious stones, but also used in industry. With technology and science continuing to develop, synthetic diamond is developing rapidly. To answer readers' confusion of synthetic diamond, there is a wonderful story, which tells readers about structure and properties of graphite and diamond, the basic method and catalysis of synthetic diamond.     

海藻异枝麒麟菜多糖抑制尿石盐草酸钙晶体生长的研究

采用扫描电子显微镜(SEM)、 红外光谱(FTIR)和X射线衍射(XRD)方法研究了从海藻异枝麒麟菜中提取的硫酸多糖(ESPS)对草酸钙(CaOxa)晶体生长的影响. 结果表明, 添加ESPS能抑制一水草酸钙(COM)的生长, 同时诱导二水草酸钙(COD)晶体的形成. 随着ESPS的质量浓度从0增加到0.03和0.50 mg/mL, COD的质量分数从0分别增加到10%和55%; COM的(1 01)晶面加强, (020)晶面减弱直至消失, 并从三维晶体转变为棱角圆顿的四角形片状晶体; COM和COD的尺寸均明显变小. 这些结果表明, ESPS是抑制CaOxa结石形成的一种潜在药物.     

A New Discovery of Calcium Phosphate Urinary Stones Formation Induced by Melamine: Nanocrystalline Assembly Mechanism

Melamine (Mel), a contaminant that has received much attention in recent years, has been adulterated into milk powder, causing a large number of infants suffering from kidney stone disease. To study the process and mechanism of calcium phosphate (CaP) stone formation induced by Mel, we simulated the formation process of CaP stones and studied the effect of Mel on crystallization in aqueous and synthetic urine systems, respectively. Ion selective electrode method was used to study the thermodynamic parameters and reaction rate of the crystallization process. It was firstly discovered that Mel could induce the formation of CaP crystals significantly under weak acidic urine conditions in which CaP cannot be stably present, so it may cause people to produce CaP stones. Thermodynamic parameter and reaction rate analysis indicated that Mel could increase the reaction tendency and accelerate the formation of CaP crystals, which was achieved by two process of electrostatic adsorption and release of calcium ions. This research is expected to provide scientific guidance for the prevention and treatment of Mel‐related stones.     

Characterization of monumental carbonate stones by thermal analysis (TG, DTG and DSC)

Thermogravimetry (TG), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC), were found to be suitable instrumental techniques for the study of monumental rocks because they need small amounts of sample and provide extensive qualitative and quantitative information. From DTG curves, the calcite/dolomite ratio in the samples as well as the differences between limestones and dolomites can be quantitatively determined. DSC curves are adequate for the identification of the degradation products in the monumental stones since they are usually salts (sometimes hydrates) which present first-order processes under 600°C. This technique makes it possible to carry out quantitative and semiquantitative analysis of the degradation of monumental rocks since it provides data about its mineralogic composition.     

Adhesion between molecules and calcium oxalate crystals: critical interactions in kidney stone formation

Kidney stones are crystal aggregates, most commonly containing calcium oxalate monohydrate (COM) crystals as the primary constituent. Notably, in vitro studies have suggested that anionic molecules or macromolecules with substantial anionic functionality (e.g., carboxylate) play an important role in crystal aggregation and crystal attachment to renal epithelial cells. Furthermore, kidney stones contain measurable amounts of carboxylate-rich proteins that may serve as adhesives and promote aggregation of COM crystals. Atomic force microscopy (AFM) measurements of adhesion forces between tip-immobilized molecules and the COM (100) surface in aqueous media, described herein, reveal the effect of functional groups on adhesion and support an important role for the carboxylate group in processes responsible for kidney stone formation, specifically macromolecule-mediated adhesion of COM crystals to cells and crystal aggregation. The presence of poly(aspartic acid) during force measurements results in a reduction in the adhesion force measured for carboxylate-modified tips, consistent with the blocking of binding sites on the COM (100) surface by the carboxylate-rich polymer. This competitive binding behavior mimics the known reduction in attachment of COM crystals to renal epithelial cells in the presence of carboxylate-rich urinary macromolecules. These results suggest a feasible methodology for identifying the most important crystal surface-macromolecule combinations related to stone formation.     

Chromium adsorption in olive stone activated carbon

In this work, Cr(III) adsorption on activated carbon obtained from olive stones in an upflow fixed-bed column at 30^∘C was studied. The flow rate influence on the breakthrough curves at a feed concentration of 0.87 meq/L was investigated in an attempt to minimize the diffusional resistances. Breakthrough curves for a flow range of 2–8 mL/min were obtained at 10.5 cm bed height and inlet diameter of 0.9 cm. The mass transfer parameters indicated that the bed minimal resistance was attained at 2 mL/min. Therefore, the data equilibrium was carried out until the bed was saturated at 2 mL/min. The dynamic system generated a favorable isotherm with a maximum chromium uptake of 0.45 meq/g. A column sorption mathematical model was created considering the axial dispersion in the column and the intraparticle diffusion rate-controlling steps. The isotherm was successfully modeled by the Langmuir equation and the mathematical model described the experimental dynamic data adequately for feed concentrations from 0.26 to 3.29 meq/L.     

Crystallization and thermal characterization of calcium hydrogen phosphate dihydrate crystals

Calcium hydrogen phosphate dihydrate (CHPD) is found quite frequently in urinary calculi (stones). The CHPD crystals were grown by the single diffusion gel growth technique in sodium metasilicate gel. The crystals were found to be having platelet and broad needle type morphologies. The crystals were analyzed by FTIR spectroscopy. The thermal properties were studied by employing the thermogravimetric analysis (TG). Various kinetic and thermodynamic parameters for dehydration were estimated from the TG curve. The selected platelet was studied by scanning electron microscope (SEM) for the growth morphologies indicating that the crystals grew in the form of leaflets having prominent (010) faces. This was in agreement with earlier reported studies.     

SOLID PHASE TRANSITION OF SYNDIOTACTIC POLYSTYRENE IN SUPERCRITICAL CO_2

Solid phase transition of the a form crystals to the β form crystals in syndiotactic polystyrene (sPS) samples hasoccurred in supercritical CO_2. This transformation is different from those detected under other conditions. The effects ofsome factors (e.g time, temperature, and pressure) on the solid phase transformation of sPS in supercritical CO_2 wereanalyzed in detail. Experimental results show that longer time, higher temperature or higher pressure favors thetransformation of the α form crystals to the β form crystals.