Integumental distribution of tyrosinase activity in the slow loris,Nycticebus coucang,and the presence of integumental tyrosinase inhibitor(s)

Résumé L'analyse radiométrique de la tyrosinase tégumentaire a montré que les régions de la peau deNycticebus coucang diffèrent enzymatiquement. Cette peau renferme un inhibiteur enzymatique de tyrosinase ainsi que des champignons.     

Inhibition of melanoma tyrosinase by fusaric acid

Zusammenfassung Nachweis, dass Fusarinsäure die DOPA-Oxydation durch Melanom-Tyrosinase kompetitiv mit DOPA hemmt.     

Activation of skin tyrosinase

Résumé L'activité de tyrosinase intégumentale est augmenté par un séjour de 10–18 jours à 0–4°C sous oxygène ou en plein air mais pas nitrogène. Les 3 espèces vertébrés qui montrent cette réaction sontMyxine glutinosa, Lepisosteus osseus etNeoceratodus fosteri.

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Contribution No. 194, Department of Biology.     

Cartilaginous tissue and nalidixic acid]

1. Medication with nalidixic acid never produced articular lesions in adult animals. 2. In the species of immature animals, if sensitive to nalidixic acid, the articular lesions were macroscopically and microscopically identical. 3. The lesions regressed spontaneously as the basal germinative layer was never affected.     

Alpha-amylase inhibitor increases plasma 3-hydroxybutyric acid in food-restricted rats

The effect on energy metabolism of delayed absorption of starch by inhibition of -amylase was examined by considering levels of plasma glucose and 3-hydroxybutyric acid (3-OHBA) in rats. Addition of -amylase inhibitor (AI) to a high starch diet delayed the plasma glucose response after feeding: peak plasma glucose levels in the control group occurred 15 min after feeding, whereas in the AI group this peak did not occur until 30 min after. The total plasma glucose response was not different between the two groups. Plasma 3-OHBA levels 1 day after food restriction increased approximately five-fold in both groups. After 3 days of food restriction, the AI group maintained the same level of plasma 3-OHBA as after 1 day of food restriction, while the control group showed significantly decreased levels of 3-OHBA. After 3 days of food restriction, plasma insulin levels were significantly decreased in the AI group compared with the corresponding levels of the control group and with levels before the restriction. There was no significant difference in body weight between the two groups. These findings suggest that delayed hyperglycemia due to delayed absorption of starch following AI loading may attenuate insulin secretion, leading to altered metabolism of 3-OHBA during the delayed response to energy deficit.     

Silymarin,an inhibitor of lipoxygenase

Summary Silybin (I), silydianin (II) and, silychristin (III), the main constituents, of silymarin, non-competitively inhibit the lipoxygenase from soybeans (EC 1.13.11.12) in vitro.F. Fiebrich, Thesis, University of Vienna 1977.H. Koch, Dt. ApothZtg118, 1844 (1978); reported in part at the Colloquium Pharmaceuticum in Münster, 21 st November 1978.     

Epileptogenic action of intra-amygdaloid injection of kainic acid]

Intra-amygdaloid unilateral application of low doses of kainic acid rapidly elicits, in both chronic and acute conditions, secondarily generalized convulsive seizures which often culminate in fatal true status epilepticus unless appropriate anti-epileptic drugs are provided. Spontaneous recurrent seizures are observed for several hours starting approximately 10 min. after the application of kainic acid. In addition to the primary degeneration in the amygdaloid complex, a secondary cell loss is seen in CA3 area of the dorsal hippocampus. It is suggested that this procedure may constitute a particularly suitable model for the study of true focalized status epilepticus.     

Formation of 2-methoxy-1,4-benzoquinone from vanillic acid by fungal laccases at various pH values

Summary Laccases of various fungi metabolize vanillic acid, but contradictory reports were found concerning the formation of 2-methoxy-1,4-benzoquinone. We could establish that the pH of the medium was the major factor affecting the formation of this product.Acknowledgment. This research was sponsored in part by a grant from the Environmental Protection Agency (R-808165) and by the Pennsylvania Agricultural Experiment Station (Journal Series No. 6673).     

Effect of tryptophan on tyrosinase in relation to vitiligo

Summary Tryptophan can inhibit DOPA (3,4-dihydroxy phenylalanine) conversion to melanin both by the enzymatic and the nonenzymatic route. Its role has been studied in relation to vitiligo.Acknowledgments. The authors wishes to thank Dr S.C. Bhattacharyya, Bose Institute and Dr A. Sen, Department of Chemistry for their interest in the work.