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1دورية أكاديمية
المؤلفون: Danilovic, Alexandre, Ferreira, Thiago Augusto Cunha, Gomes, Samirah Abreu, Wei, Isabela Akemi, Vicentini, Fabio Carvalho, Torricelli, Fabio Cesar Miranda, Marchini, Giovanni Scala, Mazzucchi, Eduardo, Srougi, Miguel, Nahas, William Carlos
المصدر: Brazilian Journal of Nephrology. June 2021 43(2)
مصطلحات موضوعية: Nephrectomy, Nephrolithiasis, Risk Factors, Struvite
الوصف: Background and objective: Magnesium ammonium phosphate stones (MAP), also known as struvite stones, are associated with urinary infection and impairment of renal unit. The aim of this study is to evaluate the urinary metabolic risk factors for recurrence of renal calculi in patients submitted to nephrectomy due to MAP stones. Methods: We retrospectively reviewed the charts of patients > 18 years old submitted to total nephrectomy due to pure MAP stones and pure calcium oxalate (CaOx) stones from July 2006 to July 2016. Urinary metabolic parameters were assessed through 24-hour urine exams ≥ 3 months after nephrectomy. Urinary metabolic parameters and new event related to lithiasis were compared. Results: Twenty-eight and 39 patients were included in MAP and CaOx group, respectively. Abnormalities in 24-hour urine samples were similar between groups. Hypercalciuria occurred in 7.1 and 10.3% of patients in MAP and CaOx group, respectively (p = 0.66), whereas hypocitraturia was present in 65.2 and 59.0% of patients with MAP and CaOx group, respectively (p = 0.41). No significant difference in new events was found between MAP and CaOx groups (17.9 vs. 23.1%, respectively; p = 0.60). Conclusion: A 24-hour urine evaluation should be offered to patients submitted to nephrectomy due to pure MAP stones in order to detect metabolic risk, improve treatment, and prevent stone recurrence.
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2دورية أكاديمية
المؤلفون: Vasconcellos, Maria L. S., Rocha, Diego P., Castro, Sílvia V. F., Silva, Luiz R.G. e, Muñoz, Rodrigo A. A., Freitas, Marcos B. J. G., Ferreira, Rafael Q.
المصدر: Journal of the Brazilian Chemical Society. September 2020 31(9)
مصطلحات موضوعية: natural fertilizer, struvite, stripping voltammetry, screen-printed gold electrode, trace metals
الوصف: We present an electroanalytical method using square-wave anodic stripping voltammetry on electrochemically-treated screen-printed gold electrodes to the simultaneous determination of lead(II), copper(II) and mercury(II) in struvite (natural fertilizer produced from urine). Electrochemical treatment via cyclic voltammetry of the working electrodes increased surface rugosity that improved the electroanalytical responses for the three metals. Under optimized conditions and using a deposition time of 90 s, the proposed method presented the following limit of detection values: 1.3 µg L-1 for lead(II), 2.0 µg L-1 for copper(II) and 0.9 µg L-1 for mercury(II). Struvite samples were easily dissolved in supporting electrolyte solution (0.05 mol L-1 HCl). Satisfactory recovery values between 91 and 111% were obtained for the analysis of spiked samples. Hence, we can infer that the proposed electroanalytical method is an effective alternative for the determination of trace metals, since it provides precise and accurate direct analyses, with rapid responses without interference from sample matrix and enabling in field analysis.
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3دورية أكاديمية
المصدر: International braz j urol. December 2018 44(6)
مصطلحات موضوعية: Struvite, Pseudomonas aeruginosa, Ascorbic Acid
الوصف: Background: Formation of struvite stones is associated with urinary tract infection by urease-producing bacteria. Biogenic crystal growth in natural and synthetic materials is regulated by the action of inhibitors, ranging from small ions, molecules to large macromolecules. Materials and Methods: We report the dynamics of in vitro crystallization of struvite in presence of vitamin C in synthetic urine using single diffusion gel growth technique. Sodium metasilicate gel of specific gravity 1.05 and the aqueous solution of ammonium dihydrogen phosphate were used as the medium for growing the struvite crystals. The crystallization process was induced by a urease positive struvite stone associated Pseudomonas aeruginosa to mimic the infection leading to stone formation. The grown crystals were characterized by ATR-FTIR and powder XRD. The surface morphology was analysed through FE-SEM for comparison between treatments. Results: We observed decrease in number, dimension, and growth rate of struvite crystals with the increasing concentrations of vitamin C. Crystals displayed well-defined faces and dendritic morphology of struvite in both control and biogenic systems. Conclusion: The results strongly suggest that, vitamin C can modulate the formation of struvite crystals in the presence of uropathogenic bacteria.
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4دورية أكاديمية
المؤلفون: Yamaçake, Kleiton G. R., Marchini, Giovanni S., Reis, Sabrina, Danilovic, Alexandre, Vicentini, Fábio C., Torricelli, Fábio C. M., Srougi, Miguel, Mazzucchi, Eduardo
المصدر: International braz j urol. October 2016 42(5)
مصطلحات موضوعية: Urolithiasis, Urinary Tract Infections, Cystinuria, struvite [Supplementary Concept]
الوصف: Purpose: To compare the clinical, metabolic, and calculi characteristics of cystine and struvite stone patients after percutaneous nephrolithotripsy (PCNL). Material and Methods: Between January/2006-July/2013, 11 cystine stone patients were treated in our clinic. Of those, 3 were excluded due to incomplete follow-up. Eight cystine stone patients (2 with bilateral disease; 10 renal units-RU) were considered for further analysis. A cohort of 8 struvite stone formers (10RU) was matched having the same age, gender, body mass index (BMI) and Guys stone score. Analyzed parameters comprised demographic data, serum/urinary metabolic evaluation and surgical outcomes. Results: Both groups had 6 female patients. Groups were similar in regards to age, gender, BMI, stone burden, and serum creatinine (p=NS). All patients had PCNL as the first surgical treatment modality. Stone free rate (SFR) after the first PCNL tended to be lower (0%) in the cystine compared to the struvite group (40%)(p=0.08). Final SFR after secondary procedures increased to 70% in cystine and 80% in struvite patients (p=1.0); mean number of procedures to achieve stone free status was higher in the first group (3.57 vs. 2.0;p=0.028). Hypocitraturia was found in all patients, but struvite cases presented with lower mean urinary citrate levels (p=0.016). Other common abnormalities were elevated urinary pH (cystine 75% and struvite 62.5%;p=1.0) and low urinary volume (62.5%,37.5%;p=0.63). Conclusion: Multiple interventions and suboptimal stone free rates are trait of the significant stone burden of struvite and cystine patients. Underlying metabolic abnormalities characterized by increased urinary pH, hypocitraturia and low urinary volume are often encountered in both populations.
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5دورية أكاديمية
المؤلفون: Hutnik, N., Wierzbowska, B., Piotrowski, K., Matynia, A.
المصدر: Brazilian Journal of Chemical Engineering. June 2016 33(2)
مصطلحات موضوعية: Struvite, Phosphate(V) ions, Zinc(II) ions, Continuous reaction crystallization, Crystal product quality, Phosphorus recycling
الوصف: Continuous reaction crystallization of struvite from aqueous solutions containing phosphate(V) (1.0 mass %) and zinc(II) ions (from 0.1 to 2.0 mg kg-1) in a continuous DT MSMPR crystallizer was investigated. The influence of pH (9 - 11) and mean residence time (900 - 3600 s) on the product characteristics and its chemical composition was tested. Struvite crystals of mean size 22-41 µm were produced. An increase in Zn2+ concentration decreased the mean crystal size and homogeneity. An elevation of the pH also decreased the struvite crystal size. Augmenting the mean residence time influenced product quality advantageously. Coexistence of struvite and Zn(OH)2 in the product was confirmed analytically.
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6دورية أكاديمية
المصدر: Rem: Revista Escola de Minas. March 2015 68(1)
مصطلحات موضوعية: Industrial magnesia compound, Hydration process, Magnesia hydration, Nutrient recovery, Struvite crystallization
الوصف: Struvite crystallization as a technique for recovering nutrients from wastewater streams has proven to be an attractive alternative to conventional treatments. The process becomes economically viable with the cost reductions related to the chemical reagents, especially magnesium ions. Thus, this study assessed the processing of a cheap and high-grade industrial magnesia compound in obtaining magnesium hydroxide slurries through a hydration reaction using different hydrating agents (magnesium acetate and sodium chloride solutions and water). The optimum hydration condition was achieved in acetate solution with a conversion rate to hydroxide about 67%. The efficiency of the obtained slurries as alternative reagents on the struvite crystallization process was evaluated in terms of the nutrient removal, NH4+-N and PO43--P. In experimental conditions of Mg2+:NH4+:PO43-ratio equal to 1.5:1.0:1.25 and pH equal to 8.5, the best results were achieved by using the magnesium hydroxide slurry obtained in acetate solution, which promoted removals of about 62% and 67% of NH4+-N and PO43--P, respectively. Finally, instrumental analysis confirmed the formation of struvite crystals in a purity degree that allows its use as a potential fertilizer.
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7دورية أكاديمية
المؤلفون: Foletto, Edson Luiz, Santos, Wilson Roberto Barreto dos, Mazutti, Marcio Antonio, Jahn, Sérgio Luiz, Gündel, André
المصدر: Materials Research. February 2013 16(1)
مصطلحات موضوعية: struvite, characterization, beverage waste, phosphorous
الوصف: In this work was investigated the influence of pH on the synthesis of struvite using cola beverage waste as source of phosphorus. The process was operated in a batch reactor. The reaction time was 20 minutes, and the chemicals MgCl2.6H2O and NH4Cl were used in the experiment, with a molar ratio of Mg+2:NH4+:PO4(3-) = 1:1:1. The products were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), surface area (BET), thermogravimetric analysis (TGA) and infra-red (IR). From the results was verified the formation of a crystalline phase at pH 9.5, with a surface area of 6.59 m² g-1 and a particle size of about 0.25 µm.
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8تقرير
المصدر: Sao Paulo Medical Journal. May 1999 117(3)
الوصف: CONTEXT: The association of primary carcinoma of the ureter and lithiasis is extremely rare. We report a rare case of a primary carcinoma of the ureter with corariform calculus. CASE REPORT: 60-year-old phaeodermal female, reported a history of right-side nephritic colic, hyperthermia and pyuria during the past 20 years and had received treatment for urinary infections a number of times. The first clinical presentation was related to lithiasis and the tumor had not been shown up by excretory urography, cystoscopy or ultrasonography. Two months after the calculus had been eliminated, the patient began to have serious symptoms and a grade III transitional cell carcinoma of the ureter was discovered. Total nephroureterectomy and M.V.A.C. (Metotrexate + Vinblastina + Doxo Rubicina + Cisplatina) chemotherapy were tried unsuccessfully. In this report we emphasize the diagnostic difficulty caused by the concomitant presence of the two pathologies. In our opinion, the rapid evolution in this case is directly related to the high grade of the tumor.
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