Until recently, conversion of arginine to agmatine by arginine decarboxylase (ADC) was considered important only in plants and bacteria. In the following, we demonstrate ADC activity in the membrane-enriched fraction of brain, liver, and kidney cortex and medulla by radiochemical assay. Diamine oxidase, an enzyme shown here to metabolize agmatine, was localized by immunohistochemistry in kidney glomeruli and other nonrenal cells. Production of labeled agmatine, citrulline, and ornithine from [3 H]arginine was demonstrated and endogenous agmatine levels (10 Ϫ 6 M) in plasma ultrafiltrate and kidney were measured by HPLC. Microperfusion of agmatine into renal interstitium and into the urinary space of surface glomeruli of Wistar-Frömter rats produced reversible increases in nephron filtration rate (SNGFR) and absolute proximal reabsorption (APR). Renal denervation did not alter SNGFR effects but prevented APR changes. Yohimbine (an ␣ 2 antagonist) microperfusion into the urinary space produced opposite effects to that of agmatine. Microperfusion of urinary space with BU-224 ( M), a synthetic imidazoline 2 (I 2 ) agonist, duplicated agmatine effects on SNGFR but not APR whereas an I 1 agonist had no effect. Agmatine effects on SNGFR and APR are not only dissociable but appear to be mediated by different mechanisms. The production and degradation of this biologically active substance derived from arginine constitutes a novel endogenous regulatory system in the kidney. ( J. Clin. Invest. 1996. 97:413-420.)

Self-medication is the selection and use of drugs without medical prescription, to treat diseases or for symptomatic relief. This article is a systematic review on self-medication in skin diseases. A search was conducted on Virtual Health Library and PubMed databases using predetermined descriptors. Two researchers performed the article selection process independently, with the degree of inter-observer agreement measured by the kappa index. The prevalence of self-medication ranged from 6.0 to 45.0%. Topical corticosteroids were the most commonly used therapeutic strategies for self-medication, as found in the reviewed articles. This study revealed that published data on self-medication in dermatology are scarce, although the findings showed that it was a common practice.

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The influence of the circadian rhythm on canine laboratory parameters is yet to be elucidated. This study aimed to investigate possible fluctuations that occur on laboratory tests of healthy dogs following overnight and over−day fasting. For this purpose, 20 adult clinically healthy dogs were enrolled in the study. Venous blood samples were obtained 7:00 am (ONF, overnight fasting) and at 7:00 pm (ODF, over−day fasting) at the same day, following a 12−hour period of respectively overnight and over−day fasting for hematological, biochemical and oxidative stress assessment. The erythrogram showed significant reduction of red blood cells, hemoglobin, hematocrit and mean corpuscular volume (MCV) measured by the cell counter following ODF. The only change seen on the leukogram was a lower lymphocyte count following ODF. No significant changes were found on platelet count, although ODF was associated with decreased mean platelet volume (MPV) and total plasma protein (TPP). ODF caused a significant reduction of total cholesterol, ALP, phosphate and triglycerides. On oxidative stress parameters, ODF reduced total oxidant capacity (TOC) and increased lipid peroxidation. In conclusion, the time of fasting can partly influence hematological, biochemical and oxidative stress parameters in dogs significantly, which warrants standardization of fasting period prior to laboratory tests in dogs, especially during research.