Melatonin in edible plants identified by radioimmunoassay and by high performance liquid chromatography-mass spectrometry.

Melatonin, the chief hormone of the pineal gland in vertebrates, is widely distributed in the animal kingdom. Among many functions, melatonin synchronizes circadian and circannual rhythms, stimulates immune function, may increase life span, inhibits growth of cancer cells in vitro and cancer progression and promotion in vivo, and was recently shown to be a potent hydroxyl radical scavenger and antioxidant. Hydroxyl radicals are highly toxic by-products of oxygen metabolism that damage cellular DNA and other macromolecules. Herein we report that melatonin, in varying concentrations, is also found in a variety of plants. Melatonin concentrations, measured in nine different plants by radioimmunoassay, ranged from 0 to 862 pg melatonin/mg protein. The presence of melatonin was verified by gas chromatography/mass spectrometry. Our findings suggest that the consumption of plant materials that contain high levels of melatonin could alter blood melatonin levels of the indole as well as provide protection of macromolecules against oxidative damage.

Increase and decrease in formic acid concentration in urine samples stored at room temperature.

Formic acid concentrations are not stable in urine samples stored at room temperature. Formic acid may increase or decrease due to bacterial contamination. Enterococci and E. coli produce formic acid under anaerobic conditions at pH values of more than 6.0. In urine sample stored at room temperature, E. coli caused a decrease in formic acid. The main substrate of formic acid formation by bacteria seems to be citric acid. Formic acid in urine is stable at room temperature for at least 7 days when concentrated acetic acid (50 microliters/10 ml) or 50 g/l thymol in isopropanol (50 microliters/10 ml) is added.

[Differentiation of renal and postrenal hematuria and proteinuria with SDS polyacrylamide gel electrophoresis and immunoblotting]. / Differenzierung renaler und postrenaler Hämaturien und Proteinurien mit SDS-Polyacrylamidgel-Elektrophorese und Immunoblotting.

The pattern of serum proteins separated by SDS-PAGE is typified by the microprotein apolipoprotein A I which is split from high density lipoprotein by SDS. High density lipoprotein is generally retained by the glomerulus and does not appear in the urine even in glomerulopathies. Thus, apolipoprotein A I is generally absent in the SDS-PAGE protein pattern of renal proteinurias. However, in postrenal hematurias and proteinurias apolipoprotein A I can be found by SDS-PAGE, immunoblotting and Ouchterlony test. Using rabbit anti-human-apolipoprotein A I as primary antibody and alkaline phosphatase-conjugated anti-rabbit immunoglobulins as secondary antibody antibody apolipoprotein A I could be detected even at a 1:128,000 dilution of blood. This means a microhematuria of only 8 microliters blood/l urine theoretically can be identified as postrenal. Unfortunately, apolipoprotein A I is not only visible on the immunoblots of postrenal hematurias and proteinurias but could also be seen in renal proteinurias. Thus, only with reservation can apolipoprotein A I be called a marker of postrenal hematuria and proteinuria. On the other hand, most renal proteinurias can be identified reliably by SDS-PAGE and analysis of apolipoprotein A I is superfluous. Apolipoprotein A I, however, could become useful in the differentiation of microhematurias without proteinuria.

[Quantitative determination of protein in the urine by a sensitive nephelometric method]. / Quantitative Proteinbestimmung im Harn mit einer empfindlichen Streulichtmethode.

The nephelometric method of Reiber ((1980) J. Clin. Chem. Clin. Biochem. 18, 123-127) for quantitation of proteins in cerebrospinal fluid was modified for urine. Protein concentrations between 50 and 500 mg/l (method A) or between 5 and 70 mg/l (method B) can be measured. Values greater than 150 mg/l correlate well with the Biuret- and the Coomassie method (r = 0.9804 and r = 0.9925, respectively). For lower concentrations, only albumin, determined by an enzyme-immuno-assay, gave a good correlation (r = 0.9342). The following pharmaceuticals did not influence the results: penicillin, gentamycin sulphate, dihydralazine sulphate, amoxicillin and furosemide. A reference range of 7-56 mg/24 h was established (n = 52, 90% confidence interval).