Vanillactic acid in the urine of melanoma patients

Catecholamines and their metabolites

The research on biosynthesis, physiology, pharmacology, regulation and degradation of catecholamines has continuously increased for more than 50 years. This is not unexpected because of the fact that catecholamines are involved in so many life processes such as nerve conduction, blood circulation and hormone regulations in health and disease. This demands that methods for their determination should be improved, and in fact during the years a number of analytical methods have been published. About 20 years ago radioenzyme techniques with thin-layer chromatographic (TLC) separation of radiolabelled catecholamine derivatives were developed which greatly contributed to our knowledge of physiological concentrations of catecholamines in biological media, particularly in plasma and brain. Radioimmune methods were successful for analysis of a number of analytes, but for catecholamines radioimmunoassays developed slowly. We believe that the greatest potential for radioimmunochemical methods lies in their ability to localize catecholamines and metabolites at the cellular and subcellular levels. With the advent of gas chromatographic-mass spectrometric (GC-MS) and high-performance liquid chromatographic (HPLC) procedures analysis of catecholamines improved greatly., The equipment for GC-MS is expensive and requires technical skillfulness, but in experienced hands a lot of new biological data have emerged. An outstanding quality with GC-MS is that the method offers the ability to identify unknown compounds and is relatively free from interferences from extraneous compounds. In comparison with GC-MS, HPLC is versatile and has gained a widespread use. Applications for research in the catecholamine field are numerous. In general, the sensitivity and specificity are satisfactory with HPLC, but it should be borne in mind that a number of pitfalls can obscure the results. This involves both sample handling, clean-up and chromatographic procedures. At present, HPLC is the most expanding field in chromatographic determination of catecholamines and their metabolites. This is particularly the case for HPLC with electrochemical detection which has revolutionized our analytical potential in this field. These chromatographic procedures continue to develop. The prerequisites for further improved methods such as capillary zone electrophoresis and combined HPLC-MS are at hand and hopefully will soon come into more general use for analysis of catecholamines in biological samples.

Clinical evaluation of a method of quantitative determination of homovanillic acid for the estimation of degree of tumor dissemination process in melanoma of the skin

Homovanillic acid (HVA) was determined both in 45 patients with different forms of melanoma and those hospitalized on the suspicion of melanoma and in 15 healthy persons. Excretion rate of homovanillic acid within the normal limits was observed in patients with benign melanotic neoplasms of the skin (4.4 +/- 0.56 mg/24 hr) and in local forms of melanotic melanoma of the skin (4.5 +/- 0.24 mg/24 hr). In patients with metastases to regional nodes as well as in patients with locally disseminated forms of melanotic melanoma of the skin the concentration of homovanillic acid increased up to 11.1 +/- 0.93 mg/24 hr. Especially strong concentration of homovanillic acid was registered in patients with disseminated malanotic melanoma of the skin, and it made up 15.7 +/- 2.04 mg/24 hr. There was evident tendency to the elevation of HVA excretion level as generalization of the process which was taking place. The data obtained enable the authors to recommend the determination of HVA excretion as an additional diagnostic test as well for prognosis of melanoma development together with other clinicomorphological data.

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.