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1.
Int J Mol Sci ; 22(4)2021 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-33668679

RESUMEN

Urine autofluorescence at 295 nm is significantly higher in patients with malignant melanoma at each clinical stage compared to the healthy group. The largest difference is in the early-stages and without metastases. With increasing stage, the autofluorescence at 295 nm decreases. There is also a significant negative correlation between autofluorescence and Clark classification. Based on our results, it is assumed that the way malignant melanoma grows also affects urinary autofluorescence.


Asunto(s)
Fluorescencia , Melanoma/orina , Triptófano/orina , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Espectrometría de Fluorescencia
2.
J Am Soc Cytopathol ; 9(1): 9-19, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31551159

RESUMEN

The color of urine, once considered by uroscopists to give the most important clues to the diagnosis, still can provide some diagnostic clues in modern medicine. Pigmented cells are an uncommon and surprising find in urine cytology and can at the same time provide important diagnostic clues or represent a dangerous pitfall. We present a review of the significance of pigmented cells in urine cytology. The presence of intracellular pigment granules; their color, size, shape, and variation in size and shape; as well as their staining reactions with special stains can provide useful diagnostic insight, especially when interpreted in the cytologic context (type of pigmented cell and its degree of atypicality) and patient's clinical context. The main differential diagnosis of cytoplasmic pigmented granules includes hemosiderin, lipofuscin, and melanin, each having a different pathogenesis and significance. The goal of this paper is to describe the morphological, histochemical, and ultrastructural characteristics of the pigments seen in urinary cytology, and to review the benign and malignant conditions associated with them.


Asunto(s)
Citodiagnóstico/métodos , Citoplasma/química , Lipofuscina/orina , Pigmentos Biológicos/orina , Orina/citología , Adulto , Anciano , Anciano de 80 o más Años , Color , Diagnóstico Diferencial , Femenino , Hemosiderina/orina , Humanos , Masculino , Melaninas/orina , Melanoma/diagnóstico , Melanoma/orina , Melanosis/diagnóstico , Melanosis/orina , Persona de Mediana Edad , Pigmentación , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/orina
3.
Medicina (Kaunas) ; 55(5)2019 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-31100919

RESUMEN

Background and objectives: Melanin, which has a confirmed role in melanoma cell behaviour, is formed in the process of melanogenesis and is synthesized from tryptophan, L-tyrosine and their metabolites. All these metabolites are easily detectable by chromatography in urine. Materials and Methods: Urine samples of 133 individuals (82 malignant melanoma patients and 51 healthy controls) were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC). The diagnosis of malignant melanoma was confirmed histologically. Results: Chromatograms of melanoma patients showed increased levels of 5,6-dihydroxyindole-2-carboxylic acid, vanilmandelic acid, homovanilic acid, tryptophan, 5-hydroxyindole-3-acetic acid, and indoxyl sulphate compared to healthy controls. Concentration of indoxyl sulphate, homovanilic acid and tryptophan were significantly increased even in the low clinical stage 0 of the disease (indoxyl sulphate, homovanilic acid and tryptophan in patients with clinical stage 0 vs. controls expressed as medium/ interquartile range in µmol/mmol creatinine: 28.37/15.30 vs. 5.00/6.91; 47.97/33.08 vs. 7.33/21.25; and 16.38/15.98 vs. 3.46/6.22, respectively). Conclusions: HPLC detection of metabolites of L-tyrosine and tryptophan in the urine of melanoma patients may play a significant role in diagnostics as well as a therapeutic strategy of melanoma cancer.


Asunto(s)
Biomarcadores de Tumor/orina , Melanoma/fisiopatología , Adulto , Anciano , Biomarcadores de Tumor/análisis , Femenino , Ácido Homovanílico/análisis , Ácido Homovanílico/orina , Humanos , Ácido Hidroxiindolacético/análisis , Ácido Hidroxiindolacético/orina , Indicán/análisis , Indicán/orina , Indoles/análisis , Indoles/orina , Masculino , Melanoma/orina , Persona de Mediana Edad , Triptófano/análisis , Triptófano/orina , Ácido Vanilmandélico/análisis , Ácido Vanilmandélico/orina
5.
Mol Imaging ; 17: 1536012118795952, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30251592

RESUMEN

CEP-32496, also known as RXDX-105 or Agerafenib, is a new orally active inhibitor for the mutated v-raf murine sarcoma viral oncogene homolog B1 (BRAFV600E), which has attracted considerable attention in clinical trials for the treatment of human cancers. Here, we used carbon-11-labeled CEP-32496 ([11C]CEP-32496) as a positron emission tomography (PET) radiotracer to evaluate its pharmacokinetic properties and explore its potential for in vivo imaging. Following radiotracer synthesis, we performed in vitro binding assays and autoradiography of [11C]CEP-32496 in the A375 melanoma cell line and on tumor tissue sections from mice harboring the BRAFV600E mutation. These were followed by PET scans and biodistribution studies on nude mice bearing subcutaneous A375 cell-induced melanoma. [11C]CEP-32496 showed high binding affinity for BRAFV600E-positive A375 melanoma cells and densely accumulated in the respective tissue sections; this could be blocked by the BRAFV600E selective antagonist sorafenib and by unlabeled CEP-32496. The PET and biodistribution results revealed that [11C]CEP-32496 accumulated continuously but slowly into the tumor within a period of 0 to 60 minutes postinjection in A375-melanoma-bearing nude mice. Metabolite analysis showed high in vivo stability of [11C]CEP-32496 in plasma. Our results indicate that [11C]CEP-32496 has excellent specificity and affinity for the BRAFV600E mutation in vitro, while its noninvasive personalized diagnostic role needs to be studied further.


Asunto(s)
Melanoma/genética , Mutación/genética , Compuestos de Fenilurea/farmacocinética , Proteínas Proto-Oncogénicas B-raf/genética , Quinazolinas/farmacocinética , Animales , Autorradiografía , Línea Celular Tumoral , Humanos , Lípidos/química , Melanoma/sangre , Melanoma/orina , Ratones Desnudos , Compuestos de Fenilurea/sangre , Compuestos de Fenilurea/química , Compuestos de Fenilurea/orina , Quinazolinas/sangre , Quinazolinas/química , Quinazolinas/orina , Distribución Tisular , Ensayos Antitumor por Modelo de Xenoinjerto
7.
Diagn Cytopathol ; 45(1): 22-28, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27775224

RESUMEN

BACKGROUND: Urine cytology is the most frequently utilized test to detect urothelial cancer. Secondary bladder neoplasms need to be recognized as this impacts patient management. We report our experience on nonurothelial malignancies (NUM) detected in urine cytology over a 10-year period. METHODS: A 10-year retrospective search for patients with biopsy-proven NUM to the urothelial tract yielded 25 urine samples from 14 patients. Two cytopathologists blinded to the original cytology diagnosis reviewed the cytology and histology slides. The incidence, cytomorphologic features, diagnostic accuracy, factors influencing the diagnostic accuracy, and clinical impact of the cytology result were studied. RESULTS: The incidence of NUM was <1%. The male:female ratio was 1.3. An abnormality was detected in 60% of the cases; however, in only 4% of the cases, a primary site was identified accurately. Of the false negatives, 96% was deemed as sampling errors and 4% was interpretational. Patient management was not impacted in any of the false-negative cases due to concurrent or past tissue diagnosis. CONCLUSION: Colon cancer was the most frequent secondary tumor. Sampling error attributed to the false-negative results. Necrosis and dirty background was often associated with metastatic lesions from colon. Obtaining history of a primary tumor elsewhere was a key factor in diagnosis of a metastatic lesion. Hematopoietic malignancies remain to be a diagnostic challenge. Cytospin preparations were superior for evaluating nuclear detail and background material as opposed to monolayer (Thinprep) technology. Diagnostic accuracy was improved by obtaining immunohistochemistry. Diagn. Cytopathol. 2016. © 2016 Wiley Periodicals, Inc. Diagn. Cytopathol. 2017;45:22-28. © 2016 Wiley Periodicals, Inc.


Asunto(s)
Biomarcadores de Tumor/orina , Neoplasias Colorrectales/patología , Errores Diagnósticos/estadística & datos numéricos , Linfoma/patología , Melanoma/patología , Neoplasias de la Próstata/patología , Orina/citología , Neoplasias Colorrectales/orina , Femenino , Humanos , Linfoma/orina , Masculino , Melanoma/orina , Sistemas Multiinstitucionales/estadística & datos numéricos , Neoplasias de la Próstata/orina
8.
Hormones (Athens) ; 15(2): 283-290, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-27376430

RESUMEN

OBJECTIVE: Adrenal masses usually represent benign and nonfunctional adrenal adenomas; however, primary or metastatic malignancy should also be considered. Discovery of an adrenal mass needs further evaluation in order to exclude malignancy and hormonal secretion. We present a rare case of a possibly primary adrenal malignant melanoma with imaging and biochemical features of a pheochromocytoma. CASE REPORT: A 61-year-old male farmer was referred for evaluation of a mass in the right supraclavicular region and a left adrenal lesion. The patient had a history of a multifocal papillary and medullary thyroid carcinoma. Laboratory tests revealed increased 24hour urinary dopamine and also increased serum calcitonin and neuron specific enolase. A pathology report of the resected right supraclavicular mass and left adrenal showed a malignant melanoma. CONCLUSION: This is a case of a possibly primary adrenal malignant melanoma with imaging and biochemical features of a pheochromocytoma. Although this case is very rare and there are rigid diagnostic criteria for the diagnosis of primary adrenal melanoma, it underlines the fact that the differential diagnosis of a dopamine secreting adrenal mass should include primary or metastatic malignant melanoma in order to determine the best diagnostic approach for the patient and select the most appropriate surgical management.


Asunto(s)
Neoplasias de las Glándulas Suprarrenales/patología , Carcinoma Neuroendocrino/patología , Carcinoma/patología , Melanoma/patología , Feocromocitoma/patología , Neoplasias de la Tiroides/patología , Neoplasias de las Glándulas Suprarrenales/sangre , Neoplasias de las Glándulas Suprarrenales/cirugía , Neoplasias de las Glándulas Suprarrenales/orina , Adrenalectomía , Biomarcadores de Tumor/sangre , Biomarcadores de Tumor/orina , Biopsia , Calcitonina/sangre , Carcinoma Papilar , Diagnóstico Diferencial , Dopamina/orina , Humanos , Inmunohistoquímica , Masculino , Melanoma/sangre , Melanoma/cirugía , Melanoma/orina , Persona de Mediana Edad , Fosfopiruvato Hidratasa/sangre , Tomografía Computarizada por Tomografía de Emisión de Positrones , Valor Predictivo de las Pruebas , Cáncer Papilar Tiroideo , Resultado del Tratamiento
9.
Diagn Cytopathol ; 41(11): 997-9, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22730159

RESUMEN

Malignant melanoma has an unusual predilection for metastasis to the small bowel, sometimes several years after the original diagnosis. In patients who have had a cystoprostatectomy followed by an ileal conduit, metastatic melanoma to the ileal conduit can present in urine cytology. We present a rare case of metastatic malignant melanoma in neo-bladder urine in a patient who had undergone a cystoprostatectomy for high grade urothelial carcinoma of the bladder and prostatic adenocarcinoma of Gleason grade 3+3 and two excisional procedures for cutaneous malignant melanoma. He presented with persistent hematuria and urinary tract infections unresponsive to treatment. Urine cytology revealed single large atypical cells, with large nuclei, prominent nucleoli, and cytoplasmic melanin pigment. Subsequent surgical resection revealed two areas of metastatic melanoma in the ileum, one of them being in the ileal conduit. The tumor cells were immunoreactive for S-100 protein, Melan-A, and HMB-45 and were negative for CAM5.2 and cytokeratins 7 and 20.


Asunto(s)
Neoplasias del Íleon/diagnóstico , Melanoma/diagnóstico , Neoplasias Cutáneas/diagnóstico , Anciano de 80 o más Años , Resultado Fatal , Humanos , Neoplasias del Íleon/secundario , Neoplasias del Íleon/orina , Masculino , Melanoma/secundario , Melanoma/orina , Neoplasias Cutáneas/patología , Neoplasias Cutáneas/orina
11.
Hautarzt ; 62(1): 51-3, 2011 Jan.
Artículo en Alemán | MEDLINE | ID: mdl-21181099

RESUMEN

A 45-year-old woman presented with diffuse melanosis, icteric sclera and melanuria. Physical examination revealed a massive nodular melanoma with ulceration and satellite metastases on the back. Further investigation showed distant cutaneous and visceral metastasis. After palliative debulking along with postoperative multidrug chemotherapy, the patient has shown objective disease regression for more than 11 months. However, it remains to be seen if disease regression will translate into increased survival.


Asunto(s)
Melanoma/diagnóstico , Melanoma/orina , Melanosis/etiología , Enfermedades de la Esclerótica/diagnóstico , Neoplasias Cutáneas/diagnóstico , Femenino , Humanos , Melaninas/orina , Melanoma/complicaciones , Melanoma/secundario , Melanoma/terapia , Melanosis/diagnóstico , Melanosis/orina , Persona de Mediana Edad , Inducción de Remisión , Enfermedades de la Esclerótica/complicaciones , Enfermedades de la Esclerótica/orina , Neoplasias Cutáneas/complicaciones , Neoplasias Cutáneas/terapia
12.
Nihon Rinsho ; 68 Suppl 7: 818-20, 2010 Jul.
Artículo en Japonés | MEDLINE | ID: mdl-20960879
13.
Clin Chim Acta ; 411(17-18): 1195-203, 2010 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-20420819

RESUMEN

BACKGROUND: Currently used as structural markers for pheomelanin identification and quantitation, benzothiazole compounds derived from isomers of cysteinyldopa have been indicated by recent in vitro studies as new potential pheomelanogenesis intermediates. The presence of benzothiazole compounds in the urine of patients with melanoma with or without diffuse melanosis was investigated. METHODS: Hydrophilic interaction liquid chromatography with zwitterionic stationary phase (ZIC-HILIC) and photo-diode array (PDA) detection was used for analysis of 6-(2-amino-2-carboxyethyl)-4-hydroxybenzothiazole-2-carboxylic acid (BTCA-5), and 7-(2-amino-2-carboxyethyl)-4-hydroxybenzothiazole-2-carboxylic acid (BTCA-2), derived from 5-S-cysteinyldopa (5-S-CD) and 2-S-cysteinyldopa (2-S-CD) isomers, respectively. After minimal sample preparation, isocratic chromatography allowed efficient separation of the compounds, which were safely identified by their typical absorption features. RESULTS: Three patients with diffuse melanosis, 16 patients with melanoma (stages III and IV) and three healthy subjects were investigated. The urinary BTCAs were found to be highly associated with melanosis but more loosely to excreted 5-S-CD. Analysis of the pigmented fraction of urine following alkaline hydrogen peroxide degradation and quantitation of BTCAs provided evidence for the presence of pheomelanins at high levels in patients with melanosis. CONCLUSION: Identification of free BTCA isomers in urine provides a significant contribution in the field of urinary melanogens, and has important implications for biosynthetic activity of normal and pathologic melanocytes.


Asunto(s)
Benzotiazoles/orina , Melaninas/orina , Melanoma/orina , Melanosis/orina , Adulto , Cromatografía Liquida/métodos , Humanos , Isomerismo , Masculino , Persona de Mediana Edad , Espectrofotometría Ultravioleta
16.
Cancer Res ; 67(16): 7833-40, 2007 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-17699789

RESUMEN

Expression of the epithelial-specific integrin alphavbeta6 is low or undetectable in most adult tissues but may be increased during wound healing and inflammation and is up-regulated dramatically by many different carcinomas, making alphavbeta6 a promising target for the in vivo detection of cancer using noninvasive imaging. In addition, alphavbeta6 is recognized as promoting invasion and correlates with aggressive behavior of human cancers and thus agents that recognize alphavbeta6 specifically in vivo will be an essential tool for the future management of alphavbeta6-positive cancers. Recently, we identified the peptide NAVPNLRGDLQVLAQKVART (A20FMDV2), derived from foot-and-mouth disease virus, as a potent inhibitor of alphavbeta6. Using flow cytometry and ELISA, we show that this peptide is highly selective, inhibiting alphavbeta6-ligand binding with a IC50 of 3 nmol/L, an activity 1,000-fold more selective for alphavbeta6 than for other RGD-directed integrins (alphavbeta3, alphavbeta5, and alpha5beta1). A20FMDV2 was radiolabeled on solid-phase using 4-[18F]fluorobenzoic acid, injected into mice bearing both alphavbeta6-negative and alphavbeta6-positive (DX3puro/DX3purobeta6 cell lines) xenografts and imaged using a small animal positron emission tomography (PET) scanner. Rapid uptake (<30 min) and selective retention (>5 h) of radioactivity in the alphavbeta6-positive versus the alphavbeta6-negative tumor, together with fast renal elimination of nonspecifically bound activity, resulted in specific imaging of the alphavbeta6-positive neoplasm. These data suggest that PET imaging of alphavbeta6-positive tumors is feasible and will provide an important new tool for early detection and improved management of many types of cancers.


Asunto(s)
Antígenos de Neoplasias/análisis , Benzoatos , Virus de la Fiebre Aftosa/química , Integrinas/análisis , Melanoma/diagnóstico por imagen , Fragmentos de Péptidos/farmacocinética , Radiofármacos , Proteínas del Envoltorio Viral/farmacocinética , Secuencia de Aminoácidos , Animales , Antígenos de Neoplasias/metabolismo , Benzoatos/química , Benzoatos/farmacocinética , Unión Competitiva , Ensayo de Inmunoadsorción Enzimática , Humanos , Integrinas/antagonistas & inhibidores , Integrinas/metabolismo , Marcaje Isotópico , Masculino , Melanoma/sangre , Melanoma/metabolismo , Melanoma/orina , Ratones , Ratones Desnudos , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Tomografía de Emisión de Positrones/métodos , Radiofármacos/síntesis química , Radiofármacos/química , Radiofármacos/farmacocinética , Proteínas del Envoltorio Viral/química
17.
J Clin Pharmacol ; 46(7): 727-37, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16809798

RESUMEN

Vincristine sulfate liposomes injection (VSLI) is a liposomal formulation of vincristine encapsulated in sphingosomes composed of sphinogomyelin and cholesterol (58/42; mol/mol). The pharmacokinetics and urinary excretion of VSLI were evaluated in 12 patients with metastatic melanoma after single-dose (2.0 mg/m2 every 2 weeks = 1 cycle) and multiple-dose (cycle 3, pharmacokinetics only) administrations (intravenous infusion over 1 hour). After VSLI infusion, total (released and encapsulated) vincristine concentrations in plasma remained relatively constant for 3 to 12 hours and thereafter declined, with interpatient variability seen in the rate of decline resulting in monoexponential or biexponential profiles. The area under the plasma concentration-time curve from time zero to infinity of total vincristine in plasma ranged from 4933 to 40495 h.ng/mL and total clearance ranged from 131 to 445 mL/h. The volume of distribution at steady state was 2650 +/- 731 mL, indicating VSLI was mainly confined within the plasma. The released vincristine concentrations in plasma were below the level of quantitation in 95% of samples. The pharmacokinetic parameters were similar between cycles 1 and 3, and trough plasma levels of total vincristine were below the level of quantitation of 1 ng/mL. Approximately 8% of the injected dose was excreted in the urine as unchanged vincristine (7%) or N-desformylvincristine (0.8%). Overall, VSLI exhibited a longer circulation half-life and higher area under the plasma concentration-time curve compared to conventional vincristine, whereas its route of elimination remained unchanged.


Asunto(s)
Antineoplásicos Fitogénicos/farmacocinética , Melanoma/orina , Vincristina/farmacocinética , Adulto , Anciano , Antineoplásicos Fitogénicos/administración & dosificación , Antineoplásicos Fitogénicos/sangre , Antineoplásicos Fitogénicos/orina , Preparaciones de Acción Retardada , Esquema de Medicación , Femenino , Humanos , Infusiones Intravenosas , Liposomas , Masculino , Melanoma/sangre , Melanoma/tratamiento farmacológico , Melanoma/patología , Persona de Mediana Edad , Neoplasias Cutáneas/orina , Vincristina/administración & dosificación , Vincristina/sangre , Vincristina/orina
18.
Pigment Cell Res ; 19(2): 163-9, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16524432

RESUMEN

Normal and malignant melanocytes produce melanins and melanin-related metabolites, most of which are retained in the cells but some are secreted into the blood and then excreted in the urine. In this study, we developed a method to measure levels of eumelanin in urine samples and evaluated its clinical significance in comparison with the melanin-related metabolites 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MI2C) and 5-S-cysteinyldopa (5-S-CD), and with pheomelanin, measured after degradation as 4-amino-3-hydroxyphenylalanine (4-AHP). The method is based on the production of pyrrole-2,3,5-tricarboxylic acid (PTCA) on permanganate oxidation of eumelanin, followed by quantification by liquid chromatography. For 118 urine samples from 10 control subjects, mean urinary excretions of PTCA, 6H5MI2C, 5-S-CD and 4-AHP were 19, 67, 37 and 59 micromol/mol creatinine respectively. In melanoma patients (n = 45), the mean urinary excretions of PTCA, 6H5MI2C, 5-S-CD, and 4-AHP were 91, 926, 4070 and 3530 micromol/mol creatinine respectively. Median level of PTCA in melanoma patients was elevated 2.1-fold compared with control subjects. The degrees of elevation for 6H5MI2C, 5-S-CD, and 4-AHP were 1.8-, 22- and 6.2-fold respectively. Thus, although urinary PTCA is of little clinical value in following the progression of melanoma, urinary 4-AHP appears to be of considerable value in this respect.


Asunto(s)
Melaninas/orina , Melanoma/orina , Neoplasias Cutáneas/orina , Adulto , Cromatografía Líquida de Alta Presión , Femenino , Humanos , Masculino , Melanoma/patología , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Neoplasias Cutáneas/patología
19.
Acta Med Austriaca ; 31(3): 76-8, 2004 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-15515481

RESUMEN

METHODS: Twenty patients suffering from malignancy received furosemide, twenty patients were examined by FDG-PET without diuretics. Urine volume and radioactivity were measured before and after acquisition. Bladder activity was evaluated qualitatively and quantitatively. RESULTS: Radioactivity in the bladder was lower and the image quality higher in the furosemide group. SUV values showed a median of 3.0 in the furosemide and 6.0 in the control group. With furosemide, a larger excreted volume was seen compared to the control group. The furosemide group showed a significantly higher ratio of excreted/ injected radioactivity early after injection. However, the totally excreted radioactivity was not significantly different (p = 0.93). CONCLUSION: Diuretics cause a higher urine volume with a diluted FDG concentration leading to an improved image quality. Furosemide accelerates early renal FDG elimination, reducing radiation exposure.


Asunto(s)
Fluorodesoxiglucosa F18/orina , Furosemida/farmacología , Melanoma/diagnóstico por imagen , Diuréticos/orina , Femenino , Furosemida/administración & dosificación , Humanos , Procesamiento de Imagen Asistido por Computador , Inyecciones Intravenosas , Masculino , Melanoma/orina , Persona de Mediana Edad , Tomografía de Emisión de Positrones , Radiofármacos/orina
20.
Pigment Cell Res ; 16(5): 480-6, 2003 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-12950724

RESUMEN

A sensitive and specific high performance liquid chromatography (HPLC) method was developed to quantify 4-amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (3-AHP) in urine. In degradation studies of melanin pigment, 4-AHP and 3-AHP are derived from benzothiazine units of pheomelanin and pheomelanin-related metabolites such as trichochromes. 5-S-Cysteinyldopa-derived benzothiazine products give 4-AHP while 2-S-cysteinyldopa-derived benzothiazine products give 3-AHP. 3-AHP is also derived from nitrotyrosine formed by nitration of tyrosine with reactive nitrogen species. For this reason, the influence of this biological process on the amount of 3-AHP found in biological material have been investigated. The method is based on hydriodic acid hydrolysis of the melanin polymer and reversed-phase HPLC with electrochemical detection of the degradation products 4-AHP and 3-AHP. The mobile phase consists of 25 mM ammonium acetate and sodium octanesulfonate as an ion-pairing reagent. The 4-AHP and 3-AHP peaks were well separated and the detector response was linear within the range 0-2 ng injected for both compounds. With the developed chromatographic system, 4-AHP and 3-AHP showed good separation in the biological samples. There was a strong correlation between 4-AHP and 3-AHP in the urine of 50 malignant melanoma patients and two healthy subjects (R0.977). The two compounds were also strongly correlated with 5-S-cysteinyldopa in urine, the correlation coefficients being 0.862 and 0.907, respectively. The method described is sensitive enough for analysis of pheomelanin in urine and in several other biological samples. The results indicate that 3-AHP in urine is not influenced by excreted 3-nitrotyrosine and the data indicate that pheomelanins are excreted in the urine of melanoma patients.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Melaninas/metabolismo , Melanoma/orina , Tirosina/análogos & derivados , Tirosina/orina , Ácidos/metabolismo , Cisteinildopa/orina , Cabello/química , Humanos , Hidrólisis , Compuestos de Yodo/metabolismo , Isomerismo
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