Cystinuria: A rare cause of bladder stone

VCystinuria is an inherited metabolic disorder progressing with recurrent kidney stones due to impaired reabsorption of dibasic amino acids and arises from mutations in the SLC3A1 and SLC7A9 on chromosome 2. Here, we present the case of a 1-year 10-month-old male child with recurrent episodes of urinary tract infections. On evaluation, duplex kidneys and a large bladder calculus were found which was surgically managed. Stone analysis and the genetic study were suggestive of cystinuria.

Research progress of cystine/glutamate antiporter as drug targets / 药学学报

Cystine/glutamate antiporter [system Xc(-)] is a sodium independent amino acid transporter, which is a heterodimer composed of light chain subunit xCT and heavy chain subunit 4F2hc (CD98) through covalent disulfide bond. System Xc(-) typically mediates cystine uptake and glutamate output, helps to maintain the balance of glutamate, cystine and cysteine inside and outside the cell, regulates the level of glutamate inside and outside the membrane and the synthesis of intracellular glutathione, thus affecting oxidative stress and glutamate neurotoxicity. This review expounds the structure and function of system Xc(-), analyzes the role of the transporter in physiology and pathology, discusses the role and mechanism in different diseases, and discusses the specific research progress of system Xc(-) as a drug target. This review summarizes the research status of system Xc(-) and provides theoretical guidance for further research on system Xc(-) and drug discovery.

Quantitative determination of D4-cystine in mice using LC-MS/MS and its application to the assessment of pharmacokinetics and bioavailability / 药物分析学报

Cystine is the primary source material for the synthesis of glutathione.However,the pharmacokinetics and tissue distribution of cystine are largely unknown.A surrogate analyte D4-cystine was employed to generate calibration curves for the determination of levels of D4-cystine and endogenous cystine in mice by liquid chromatography-tandem mass spectrometry(LC-MS/MS).Validation assessments proved the sensitivity,specificity and reproducibility of the method with a lower limit of quantification(LLOQ)of 5 ng/mL over 5-5000 ng/mL in plasma.The pharmacokinetics of D4-cystine were evaluated after administering injections and oral solutions,both of which minimally impacted endogenous cystine levels.The absolute bioavailability of cystine was 18.6％,15.1％and 25.6％at doses of 25,50 and 100 mg/kg,respectively.Intravenously injected D4-cystine resulted in dramatically high plasma levels with reduced levels in the brain and liver.Intragastrically administered D4-cystine resulted in high levels in the plasma and stomach with relatively low levels in the lung,kidney,heart and brain.

Regulation of cysteine metabolism and new strategies for cancer treatment / 中国药科大学学报

@#In order to sustain prodigious anabolic needs, tumor cells need metabolic reprogramming that differs from untransformed somatic cells.Besides glucose metabolism in tumor, amino acid metabolism also plays an important role in tumor cell proliferation, migration, and invasion.It is an emerging trend in tumor energy metabolism research.The metabolic pathway of cysteine, a glucose-producing amino acid, involves a variety of enzymes and products, regulating physiological and pathological processes such as oxidative stress, energy metabolism, and autophagy.This article focuses on the exogenous transport and endogenous conversion pathways of cysteine in tumor cells, the various regulatory mechanisms of cysteine metabolism pathways on the occurrence and development of tumors, and the potential therapeutic targets based on cysteine metabolism pathways, which can provide a theoretical basis for clinical use of drugs against tumors.

Cystine transporter SLC7A11/xCT in cancer: ferroptosis, nutrient dependency, and cancer therapy

The cystine/glutamate antiporter SLC7A11 (also commonly known as xCT) functions to import cystine for glutathione biosynthesis and antioxidant defense and is overexpressed in multiple human cancers. Recent studies revealed that SLC7A11 overexpression promotes tumor growth partly through suppressing ferroptosis, a form of regulated cell death induced by excessive lipid peroxidation. However, cancer cells with high expression of SLC7A11 (SLC7A11

Risk Assessment of “Other Substances” - L-cysteine and L-cystine

The Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) has, at the request of the Norwegian Food Safety Authority (Mattilsynet; NFSA), assessed the risk of “other substances” in food supplements and energy drinks sold in Norway. VKM has assessed the risk of doses given by NFSA. These risk assessments will provide NFSA with the scientific basis while regulating the addition of “other substances” to food supplements. “Other substances” are described in the food supplement directive 2002/46/EC as substances other than vitamins or minerals that have a nutritional or physiological effect. It is added mainly to food supplements, but also to energy drinks and other foods. VKM has not in this series of risk assessments of “other substances” evaluated any claimed beneficial effects from these substances, only possible adverse effects. The present report is a risk assessment of L-cysteine and L-cystine, and is based on previous risk assessments of these amino acids and articles retrieved from a comprehensive literature search. In this report L-cysteine and L-cystine are often termed merely cysteine and cystine, respectively. L-cysteine is a central compound in sulphur metabolism in the human body. L-cysteine is a conditionally essential sulphur-containing amino acid, obtained from L-methionine and from serine. Sulphur-containing amino acids are mainly found in cereal proteins and animal proteins, and less abundantly in pulses. Cysteine may occur in proteins either as cysteine itself or as cystine. Cystine is the disulphide dimer of cysteine, and is a more stable compound than cysteine. According to information from the Norwegian Food Safety Authority (NFSA), cysteine and cystine are ingredients in food supplements purchased in Norway and NFSA has requested a risk assessment of the following doses of cysteine and cystine in food supplements: L-cysteine 10 mg/day and L-cystine 250, 500, 750 and 1000 mg/day. The mean usual daily intake of cysteine in the USA for all life stage- and gender groups is 1.0 g/day (NHANES II, USA). Because there are few intervention studies with cysteine or cystine, studies with N-acetylcysteine (or N-acetyl-L-cysteine, NAC), which is readily converted to cysteine, is included in this risk assessment. NAC is used as a pharmaceutical drug for various conditions, mainly as mucolytic agent, as paracetamol antidote, and has been included in numerous clinical trials. Most of the cited studies have tested NAC in doses of about 600-1200 mg/day. The study groups have been various patient groups which included children, adolescents, adults and elderly, however relatively few studies have been conducted in children. In the randomised controlled trials there have been no differences in severe adverse events between the placebo and NAC-groups. The adverse effects reported are generally limited to mild gastrointestinal symptoms. The dose 1200 mg of NAC yields maximum 900 mg of L-cysteine or L-cystine. In adults, it is well documented that doses up to 900 mg per day for one year (corresponding to 13 mg/kg bw/day in a 70 kg adult) is without appreciable health risk. The data for doses above 900 mg/day are more scarce. There are no data indicating that children and adolescent are more vulnerable than adults for L-cysteine or L-cystine. No tolerance level is set for cysteine or cystine specifically for children or adolescents, but an assumption is made that these age groups have similar tolerance per kg body weight as adults. VKM concludes that: In adults (≥18 years), the specified doses 10 mg/day L-cysteine and 250, 500 and 750 mg/day L-cystine in food supplements are considered to be unlikely to cause adverse health effects, whereas the dose 1000 mg L-cystine per day may represent a risk of adverse health effects. In adolescents (14 to <18 years), the specified doses 10 mg/day L-cysteine and 250, 500 and 750 mg/day L-cystine in food supplements are considered to be unlikely to cause adverse health effects in adolescents, whereas the dose 1000 mg L-cystine per day may represent a risk of adverse health effects. In children (10 to <14 years), the specified doses 10 mg/day L-cysteine and 250 and 500 mg/day L-cystine in food supplements are considered to be unlikely to cause adverse health effects, whereas the doses 750 and 1000 mg L-cystine per day may represent a risk of adverse health effects. Children below 10 years were not included in the terms of reference.

Thiol/disulfide status regulates the activity of thiol-containing kinases related to energy homeostasis in rat kidney

ABSTRACT Considering that thiol-containing enzymes like kinases are critical for several metabolic pathways and energy homeostasis, we investigated the effects of cystine dimethyl ester and/or cysteamine administration on kinases crucial for energy metabolism in the kidney of Wistar rats. Animals were injected twice a day with 1.6 µmol/g body weight cystine dimethyl ester and/or 0.26 µmol/g body weight cysteamine from the 16th to the 20th postpartum day and euthanized after 12 hours. Pyruvate kinase, adenylate kinase, creatine kinase activities and thiol/disulfide ratio were determined. Cystine dimethyl ester administration reduced thiol/disulfide ratio and inhibited the kinases activities. Cysteamine administration increased the thiol/disulfide ratio and co-administration with cystine dimethyl ester prevented the inhibition of the enzymes. Regression between the thiol/disulfide ratio, and the kinases activities were significant. These results suggest that redox status may regulate energy metabolism in the rat kidney. If thiol-containing enzymes inhibition and oxidative stress occur in patients with cystinosis, it is possible that lysosomal cystine depletion may not be the only beneficial effect of cysteamine administration, but also its antioxidant and thiol-protector effect.

TFEB regulation:new insight into treatment of kidney diseases / 中国病理生理杂志

Transcription factor EB(TFEB)is a member of the MiTF/TFE family and plays an important role in cell stress,metabolism,cancer and so on.There are relatively few studies on the role of TFEB in renal diseases.TFEB was initially found to be highly expressed in TFEB-fusion renal cell carcinoma and plays a key role in the development of re-nal cell carcinoma.Blocking the downstream signaling pathway activated by TFEB would be a promising treatment for TFEB-fusion renal cell carcinoma.On the contrary,the expression of TFEB in renal intrinsic cells is decreased in diabetic kidney disease,leading to a blockage in the autophagy-lysosome pathway.TFEB enhances the ability of cell stress and self-repair,and then delays the progress of diabetic kidney disease.In cystine nephropathy,TFEB expression is reduced in re-nal tubular epithelial cells and compensatory activation is insufficient as well.TFEB over-expression effectively eliminates intracellular cystine and repairs damaged lysosome,which is expected to alleviate or cure the Fanconi syndrome.In summa-ry,TFEB plays a key role in different kidney diseases,and targeted regulation of TFEB provides new hope for the treatment of kidney diseases.

Progress of diagnosis and treatment for Gitelman syndrome and cystinosis / 中华实用儿科临床杂志

Gitelman syndrome(GS) is an autosomal recessive,salt-losing tubulopathy resulted from inactivating mutations in the SLCl2A3 gene that encodes the Thiazine diuretic sensitive sodium chloride cotransporter (NCCT).GS is characterized by hypokalemic metabolic alkalosis,hypomagnesemia and hypocalciuria.Diagnosis of GS is relied on the clinical symptoms,biochemical abnormalities and genetic test.All GS patients are suggested to keep high-sodium diet.Magnesium and potassium supplements are usually given to GS patients for lifelong to improve clinical symptoms.Individual management of GS includes health education,complication evaluation and regular follow-up with annual evaluation by a nephrologist.Cystinosis is a rare autosomal-recessive lysosomal storage disease caused by inactivating mutations in the CTNS gene that encodes the lysosomal cystine transporter,cystinosin,resulting in the accumulation of cystine within the lysosome.There are 3 clinical forms of cystinosis:infantile or early-onset nephropathic cystinosis,juvenile or late-onset nephropathic cystinosis and adult or ocular cystinosis.Diagnosis of cystinosis is based on the CTNS genetic test.Early diagnosis and early cystine-depleting therapy with cysteamine is essential to prevent or attenuate end-organ damage and improve overall prognosis.

The role of cystine/glutamate antiporter on the pathogenesis of glioma and the relative applications of anesthetics / 中国医师杂志

The incidence of glioma has been increasing in recent years,and threatened the human health seriously.Cystine/glutamate antiporter (system xc-) is one of the important glutamate transporters in the central nervous system,both the expression of system xc and the extracellular glutamate concentration increase in the course of brain tumor's development.Hence system xc-plays an essential role in the process of brain tumor genesis,it has become an important research field in brain tumor in the past decades.Our present review expound the important role of system xc-in the process of glioma genesis and development as well as provide theoretical foundation and new strategies for the clinical treatment and the application of drugs by connecting with anaesthetics and the effects of system xc on glioma.

Efecto de la combinación de bases nutritivas con el inhibidor sobre la recuperación de salmonelas / Effect of combining nutrient bases and inhibitor on recovery of Salmonella

INTRODUCCIÓN: las salmonelas son las causantes más frecuentes de enfermedades transmitidas por alimentos a nivel mundial. El caldo selenito cistina es un medio de enriquecimiento selectivo utilizado para la recuperación de especies de salmonelas en muestras de alimentos, aguas, heces y otros materiales de importancia sanitaria. OBJETIVO: evaluar la combinación de bases nutritivas obtenidas por métodos originales con el selenito de sodio para garantizar la adecuada recuperación de especies de salmonelas en el caldo selenito cistina. MÉTODOS: se realizó un estudio comparativo con diferentes bases nutritivas, que evaluó la promoción de crecimiento bacteriano de seis cepas de Salmonella y Shigella. Se prepararon dos variantes y se inocularon los microorganismos seleccionados a una concentración aproximada de 3 × 108 unidades formadoras de colonia por mililitro. El incremento de la biomasa se determinó a través de la medición de la absorbancia en un espectrofotómetro a 640 nanómetros cada una hora. Se comparó el comportamiento del medio caldo selenito cistina formulado por ingredientes con el caldo selenito cistina de Merck frente a los microorganismos de interés. Se determinó productividad y selectividad del medio de cultivo. RESULTADOS: la variante que contiene la mezcla de bases nutritivas (peptona bacteriológica Z, peptona de soya e hidrolizado enzimático de caseína) facilitó una mejor recuperación de las cepas ensayadas, mostró diferencias significativas (p< 0,05) con respecto a la variante que contiene solo hidrolizado enzimático de caseína. El medio experimental que contenía la mezcla de bases nutritivas con el selenito de sodio, mostró una recuperación de Salmonella a bajas concentraciones, similar al de referencia e inhibió mejor Escherichia coli a bajas concentraciones. A altas concentraciones ninguno de los dos medios pudo inhibir el crecimiento de E. coli. La productividad para ambos medios, resultó satisfactoria en el intervalo de 0,1 a 1, al igual que la selectividad con un valor aproximado de 3. CONCLUSIONES: la combinación de bases nutritivas originales con el selenito de sodio permitió una adecuada recuperación de las especies de salmonelas.

INTRODUCTION: Salmonella are the most common causes of food-borne disease worldwide. Selenite cystine broth is a selective enrichment medium used for the recovery of Salmonella species in samples of food, water, feces and other materials of clinical importance. OBJECTIVE: Evaluate the combination of nutrition bases obtained by original methods and sodium selenite to ensure appropriate recovery of Salmonella species in selenite cystine broth. METHODS: A comparative study was conducted with various nutrition bases to evaluate the fostering of bacterial growth in six strains of Salmonella and Shigella. Two variants were prepared and the microorganisms selected were inoculated at an approximate concentration of 3 × 108 colony-forming units per milliliter. Absorbance was measured with a 640 nanometer spectrophotometer every hour to determine biomass increase. Behavior of the selenite cystine broth medium formulated by ingredients was compared with that of Merck cystine selenite broth in the presence of the microorganisms of interest. Determination was performed of the productivity and selectivity of the culture medium. RESULTS: The variant containing the mixture of nutrient bases (bacteriological peptone Z, soybean peptone and casein enzymatic hydrolysate) facilitated better recovery of the strains tested, with significant differences (p< 0.05) with respect to the variant containing casein enzymatic hydrolysate alone. The experimental medium containing the mixture of nutrient bases and sodium selenite displayed Salmonella recovery at low concentrations in a manner similar to the reference medium and inhibited Escherichia coli more efficiently at low concentrations. At high concentrations neither medium was able to inhibit the growth of E. coli. Productivity was satisfactory in both media, ranging between 0.1 and 1, and so was selectivity, which reached an approximate value of 3. CONCLUSIONS: The combination of original nutrition bases and sodium selenite allowed appropriate recovery of Salmonella species.

Cystine knot peptide′s properties and its applications for drug design and molecu-lar engineering / 药学实践杂志

The cystine knot (CK) motif comprises an internal ring formed by two disulfide bonds and their connecting backbone segments which is threaded by a third disulfide bond .It is present in peptides and proteins of a variety of species ,in-cluding fungi ,plants ,marine molluscs ,insects and spiders .CK polypeptide is one of the ideal model molecules for drug design and molecular engineering research because of its stable structure and variety of bioactivities .Here we summarized the main structural features of both inhibitor cystine knot (ICK) peptide and cyclic cystine knot (CCK) peptide ,including primary se-quence ,topology ,permutation ,synthesis and folding characteristics ,as well as its applications on drug design and molecular engineering .

Endocrine complications during and after adolescence in a patient with cystinosis

Cystinosis is a rare disease characterized by abnormal lysosomal cystine accumulation of cystine due to impaired lysosomal transport. We previously reported the first case of cystinosis in Korea in a 12-year-old boy with short stature, general weakness, and photophobia. The diagnosis was confirmed based on ophthalmic findings and biochemical analyses (serum leukocyte cystine measurement). Major endocrine manifestations at diagnosis included hypothyroidism, growth retardation, and hypogonadism. Despite oral cysteamine administration and renal replacement therapy, multiple complications including both endocrine and nonendocrine disorders developed during and after adolescence. In this report, we review the presenting features and factors related to the long-term complications in a patient with cystinosis.

Research on the value of methionine loading test in the mild vascular cognitive impairment / 中华老年医学杂志

Objective To study the value of methionine loading test (MLT) in the mild vascular cognitive impairment (VCI) after acute cerebral infarction.Methods The fasting plasma homocystine (Hcy) level and homocystine level after MLT were measured by high-performance liquid chromatography methods.We chose 240 patients with normal level of fasting plasma Hcy (normal group),159 patients with normal level of Hcy after MLT,81 patients with hyperhomocysteinemia after MLT (hyperhomocysteinemia group),and 112 patients with fasting hyperhomocysteinemia (fasting hyperhomocysteinemia group) in this study.The Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE) were conducted in normal,hyperhomocysteinemia and fasting hyperhomocysteinemia groups on admission,at 7d,14 d,30 d after treatment.Results Logistic regression analysis showed that the increased level of Hcy might be an independent risk factor for VCI [OR:1.285,95％CI:1.038-1.265,P＜0.05].The scores of MMSE and MoCA were lower in patients with fasting hyperhomocysteinemia and patients with hyperhomocysteinemia after MLT than in patients with normal fasting plasma Hcy at 7 d,14 d and 30 d after treatment (P＜0.01 or 0.05),while the scores had no significant differences among the three group on admission (P＞0.05).There were no significant differences in MMSE and MoCA scores between patients with fasting hyperhomocysteinemia and patients with hyperhomocysteinemia after MLT on admission,7 d,14 d and 30 d after treatment (P＞0.05).Conclusions Hcy may be an independent risk factor for VCI.The MLT can discover the dormant vascular risk factors for VCI,which offers a valuable detection method for early intervention and prevention in the clinical medicine.

Effect of Nocturnal Hypertension in Primary Hypertension Patients With Early Renal Dysfunction / 中国循环杂志

Objective: To investigate the effect of nocturnal hypertension in essential hypertension (EH) patients with early renal dysfunction. Methods: A total of 182 EH patients were enrolled in this study. According to weather the average night blood pressure (BP) > 120/70 mmHg, the patients were divided into 2 groups: Nocturnal hypertension group,n=89 and Control group,n=93. The levels of urine micro albumin (mALB), podocalyxin (PCX) and serum Cyst-C were examined and compared between 2 groups. Results:① For BP: the average systolic and diastolic BP in Nocturnal hypertension group were higher than those in Control group as SBP (138.05 ± 6.33) mmHg vs (102.51 ± 8.76) mmHg, DBP (84.11 ± 6.32) mmHg vs (70.03 ± 4.56) mmHg, P<0.05. ② For renal dysfunction biomarkers: several biomarker levels were higher in Nocturnal hypertension group than those in Control group as mALB (13.60 ± 0.69) mg vs (10.04 ± 0.73) mg, PCX (5.35 ± 1.69) ng/ml vs (2.05 ± 0.88) ng/ml and serum Cyst-C (1.35 ± 0.69) mg/L vs (1.02 ± 0.44) mg/L, allP<0.05.③ For correlation study: In Nocturnal hypertension group, the PCX level was positively correlated to the levels of mALB (r=0.675,P<0.05), Cyst-C (r=0.734,P<0.05), night BP (r=0.830, P<0.05) and the duration EH (r=0.688,P<0.05). Conclusion: EH patients with nocturnal hypertension have more incidences to suffer from renal dysfunction, the examination of mALB, PCX and Cyst-C are beneifciary for the early diagnosis in relevant patients.

Extracellular cysteine/cystine redox potential affects mitochondrial func-tion in NAFLD LO2 cells / 中国病理生理杂志

AIM:To investigate the effects of extracellular cysteine/cystine redox potential (EhCys/CySS) on the mitochondrial function of nonalcoholic fatty liver disease ( NAFLD) hepatocytes.METHODS:LO2 cells were incuba-ted with EhCys/CySS of the oxidized (0 mV), the normal (-80 mV), or the reduced (-150 mV) status medium, then treated with oleic acid to establish NAFLD model in vitro.DCFH-DA and MitoSOX were used as the fluorescent probes for determining reactive oxygen species (ROS).Apocynin (NADPH oxidase inhibitor), MitoQ10 (mitochondria-targeted an-tioxidant), rotenone (mitochondrial respiratory chain complex I inhibitor) and antimycin A (mitochondrial respiratory chain complex III inhibitor) were used to investigate the sources of ROS.RESULTS:An increase in ROS in LO2 cells by oleic acid was aggravated by the oxidized extracellular EhCys/CySS (0 mV), which was removed by the reduced EhCys/CySS (-150 mV) .ROS generation by 0 mV was significantly eliminated by MitoQ10 .ROS levels were dependent on ex-tracellular Eh Cys/CySS in rotenone treated LO2 cells.A decline of mitochondrial membrane potential in the cells with NAFLD was aggravated by 0 mV and reversed by -150 mV.CONCLUSION:The oxidized extracellular Eh Cys/CySS via inhibitiing of complex I intensifies ROS generation and reducing the mitochondrial membrane potential in the NAFLD hepa-tocytes, which were reversed by reduced Eh Cys/CySS.

Cuantificación de cistina en orina espontánea para la detección de cistinuria / Quantitation of urinary cystine for the detection of cystinuria / Determinagáo quantitativa de cistina urinaria para a detecgáo de cistinuria

La cistinuria es un error innato del metabolismo ocasionado por un defecto en el transporte renal de arginina, ornitina, lisina y cistina. La acumulación de este último aminoácido de baja solubilidad ocasiona episodios de urolitiasis característicos de la enfermedad. En el presente estudio se estandarizó un método espectrofotométrico confiable y de fácil ejecución para la determinación cuantitativa de cistina en orina espontánea. Se realizó el análisis en 184 muestras, correspondientes a 104 controles y 80 pacientes con urolitiasis. Con el objeto de validar el método y posteriormente establecer un rango de excreción normal en la población colombiana se evaluaron los siguientes parámetros: exactitud, precisión, linealidad y límite de detección. La técnica mostró coeficientes de variación intra e inter ensayos inferiores al 10% y una excelente linealidad, con un coeficiente r² entre concentraciones conocidas de cistina y absorbancia generada por el método de 0,998. Usando esta técnica se encontró un valor normal de excreción de 1,35 a 110,11 mg cistina/g creatinina. En cinco pacientes, de los 80 con nefrolitiasis, se hallaron valores elevados de cistina, compatibles con cistinuria. El método utilizado puede implementarse en cualquier laboratorio clínico para confirmar el diagnóstico de cistinuria e iniciar un tratamiento oportuno.

Cystinuria is an inborn error of metabolism, caused by a defect in renal tubular transport of the following aminoacids: arginine, ornithine, lysine and cystine. Accumulation of the latter poorly soluble aminoacid leads to the development of kidney stones, characteristic of the disease. In this study, an easy and dependable spectrophotometric method for the quantitative determination of urinary cystine was standardized. The analysis was performed on 184 samples from 104 controls and 80 patients with kidney stones. In order to validate the method and later establish a range of normal urinary cystine excretion in the Colombian population, the following parameters were evaluated: Accuracy, precision, linearity and lower limit of detection. The technique showed intra and intei assay coefficients of variation below 10%, and excellent linearity, with an R square (r²) coefficient between known cystine concentrations and absorbance generated by the method at 0.998. Using this technique, a normal urinary cystine excretion range of 1.35-110.11 mg cystine/g creatinine was found. Among the 80 patients with kidney stones, elevated urinary cystine levels were found in 5 of them, compatible with the presence of cystinuria. This method can be implemented in any clinical laboratory to confirm the diagnosis of cystinuria and provide opportune treatment.

A cistinúria é um erro inato do metabolismo, causado por um defeito no transporte tubular renal de ar-ginina, ornitina, lisina e cistina. A acumulagáo deste último aminoácido, pouco solúvel, provoca episodios de urolitíase, característicos da doenga. No presente estudo, foi padronizado um método espectrofotomé-trico confiável e de fácil execugáo para a determinagáo quantitativa de cistina em urina espontánea. A análise foi realizada em 184 amostras de 104 controles e 80 pacientes com urolitíase. A fim de validar o método e, posteriormente, estabelecer um intervalo de excregao normal na populagao colombiana, foram avaliados os seguintes parámetros: exatidáo, precisáo, linearidade e limite inferior de detecgáo. O método mostrou coeficientes de variagáo intra e inter ensaios inferiores a 10%, e excelente linearidade, com um coeficiente R quadrado (r²) entre concentragoes conhecidas de cistina e absorváncia gerada pelo método de 0,998. Com esta técnica, foi encontrado um valor normal de excregáo de 1,35-110,11 mg cistina/g de creatinina. Entre os 80 pacientes com urolitíase, foram encontrados níveis elevados de cistina em cinco deles, compatíveis com a presenga de cistinúria. Este método pode ser implementado em qualquer laboratorio clínico para confirmar o diagnóstico de cistinúria e proporcionar um tratamento oportuno.

Descrição do potencial de retenção de nitrogênio em frangas de postura por diferentes metodologias: máxima deposição e estimativas da ingestão de metionina+cistina / Description of the potential for nitrogen retention in pullets by different methodologies: maximum deposition and estimates of intake of methionine+cystine

Objetivou-se descrever o máximo potencial de deposição de nitrogênio e estimar a ingestão de metionina+cistina pela técnica do balanço de nitrogênio e abate comparativo. Foram realizados ensaios no período de 14 a 28, 56 a 70 e 98 a 112 dias de idade, utilizando 168 frangas Dekalb White, distribuídas em sete tratamentos e oito repetições. Os tratamentos consistiram de níveis de proteína na dieta, variando de 75 a 435 g kg-1 de matéria seca, em que a metionina+cistina foi o primeiro aminoácido limitante. As variáveis coletadas pelo abate comparativo foram nitrogênio ingerido e depositado e, nos ensaios de balanço de nitrogênio, coletaram-se ingestão e excreção de nitrogênio. Por meio da relação exponencial entre ingestão e deposição de nitrogênio, determinou-se a máxima deposição de nitrogênio. As técnicas foram comparadas pelo teste da razão de máxima verossimilhança. As técnicas descrevem de forma diferente o máximo potencial de deposição pela ave, mas são similares na estimativa da exigência de metionina+cistina. Com base em 60% do máximo potencial, as ingestões de metionina+cistina digestível foram estimadas em 163, 243 e 343 mg dia-1 para os período de 14 a 28, 56 a 70 e 98 a 112 dias de idade, respectivamente.

This study aimed to describe the maximum potential of nitrogen deposition and to estimate the intake of methionine+cystine by nitrogen balance and comparative slaughter. Assays were performed in the periodsof 14 to 28, 56 to 70 and 98 to 112 days of age, using 168 Dekalb White pullets, distributed in seven treatments and eight replications. Treatments consisted of protein levels in the diets ranging from 75 to 435 g kg-1 dry matter in which methionine+cystine was the first limiting amino acid. The variables collected by comparative slaughter were nitrogen intake and deposition and, in nitrogen balance trials were collected nitrogen intake and excretion. With the exponential relationship between nitrogen intake and deposition was determined the maximum nitrogen deposition. The techniques were compared by the test of maximum likelihood ratio. The techniques described differently the maximum potential for deposition by the bird, but were similar in the estimation of methionine+cystine. Based on 60% of the maximum potential the intakes of digestible methionine+cystine were estimated at 163, 243 and 343mg day-1 for the period of 14 to 28, 56 to70 and 98 to 112 days of age, respectively.

Refolding of recombinant human granulocyte colony stimulating factor: Effect of cysteine/cystine redox system.

Granulocyte colony-stimulating factor (G-CSF) is a multi-functional cytokine which is widely used for treating neutropenia in humans. Evaluation of alternative to expensive components of redox buffer (reduced and oxidized glutathione) is an important step in reducing the cost of production of human biotherapeutic proteins. In the present study, refolding of recombinant human G-CSF expressed as inclusion bodies (IBs) in E. coli was optimized using cysteine and cystine redox agents. The refolding to correct native form of G-CSF was assessed by reverse phase high performance liquid chromatography (RP-HPLC). The optimized concentrations of cysteine and cystine for correct refolding of G-CSF were found to be 2 mM and 1 mM, respectively. The correctly refolded G-CSF was detected as early as 4 h of incubation in renaturation buffer containing optimized concentrations of cysteine (2 mM) and cystine (1 mM) redox agents. Refolding of G-CSF in optimized redox system increased with increase in shuffling time. Overall, the results suggested the use of cysteine/cystine redox pair could be an alternative to the costlier redox pairs for successful refolding of G-CSF and possibly other human biotherapeutic proteins of importance.