Comparison of the excretion of different types of melanogens in the melanoma patients.

Urinary melanogens are indolic and phenolic compounds which are excreted in an elevated amount in the urine of melanoma patients. Urinary melanogens can be divided into two principal groups according to their behavior during Thormählen test--Thormählen positive melanogens (TPM) and Thormählen negative melanogens (TNM). When comparing TPM and TNM (represented by homovanillic and vanillactic acids) urinary excretion in stage III of melanoma patients we have found two significantly different relations for melanogens excretion, i. e. predominating TPM urinary excretion in melanotic forms of melanomas and predominating homovanillic acid and vanillactic acid urinary excretion in amelanotic forms of melanomas. We assumed that it could be an indirect evidence of the different catalytic activity of either cresolase or catecholase activities of tyrosinase.

Excretion of vanilmandelic acid in the urine of retinoblastoma patients.

The idea of determining the urinary excretion of vanilmandelic acid (VMA) in children with retinoblastoma derives from the fact that elevated amounts of VMA were found in children with neurogenic tumours and especially neuroblastoma. The method of VMA analysis and the results are discussed. In view of the fact that in only 5 out of our 12 patients an elevated urinary VMA excretion was found, we cannot recommend this determination as a routine diagnostic procedure. However, further research in this direction is necessary.

Normal urinary excretion of catecholamine catabolites in children with retinoblastoma.

Urinary catecholamine catabolites, homovanillic acid, vanillylmandelic acid, total metanephrines, and total catecholamines were assayed in 12 patients with newly diagnosed retinoblastoma prior to surgery and treatment. These values were within normal limits for the ages of all 12 patients, including one with metastases to brain, liver, lymph nodes, and bone marrow. The predictive value and efficiency of these tests in the diagnosis of retinoblastoma are insufficient to warrant their continued use on a routine basis.

5-S-cysteinyldopa in the urine of melanoma patients.

A newly discovered amino acid, 5-S-cysteinyldopa, present in the urine of healthy subjects is excreted in pathological amounts in many patients suffering from melanoma metastases. Increased excretion of 5-S-cysteinyldopa may be observed before metastases become clinically evident. Determination of 5-S-cysteinyldopa is superior to determination of dopa+dopamine in the diagnosis of melanoma metastases.

Simple and sensitive test for the determination of phenolic compounds in urine and its application to melanoma.

A simple procedure is outlined for the determination of phenolic compounds in urine. The method involves the diazotization of p-nitroaniline and subsequent coupling of the diazonium chloride with phenolic compounds. The diazo compound formed is determined by measuring the absorbance at 400 nm. The extinction coefficients for several compounds have been determined. Application of this method to determine the levels of phenolic compounds in urine in patients with melanoma showed that the assay may be of diagnostic value. The amounts of phenols in 24-hr urine samples from patients with melanoma, patients with various other diseases, and healthy individuals were determined. A statistical analysis of these results showed that the results for patients with melanoma were higher than those for healthy individuals and patients with other diseases at 1 percent probability level. A comparison of this test with three other methods (Thormählen test, ferric chloride test, and ferrocitrate test) for determination of melanogens showed that the diazo test is the most sensitive one for detecting melanoma.