-The DOPA-decarboxylase (aromatic-L-amino acid decarboxylase) inhibitors benserazide, its active metabolite 2,3,4-trihydroxybenzylhydrazine and carbidopa are substrates of highly purified catechol-O-methyltransferase. The affinity and maximal velocity of both benserazide and trihydroxybenzyl hydrazine are extremely favourable implying that these compounds may compete as substrates for catechol-...

Synthetic mesoporous alumina and silica minerals with uniform pore geometries, and their nonporous analogues, were used to test the role of mineral mesopores (2-50 nm diameter) in protecting organic matter from enzymatic degradation in soils and sediments. Dihydroxyphenylalanine (L-DOPA), a model humic compound, was irreversibly sorbed to both mineral types. The surface area-normalized adsorpti...

The distribution of Langerhans cells (LCs) in human corneal and conjunctival epithelial sheets was investigated by histochemical, immunofluorescence, and immuno-electron microscopic methods. The LCs stained positive with ATPase and with antibodies to HLA-DR antigen and were negative to DOPA-oxidase. Human conjunctiva showed 250 to 300 LCs/mm2 compared to 15 to 20/mm2 in the peripheral third of ...

OBJECTIVE The authors' goal was to study presynaptic dopamine activity in smoking and nonsmoking human subjects in vivo. METHOD [(18)F]Fluorodopa ([(18)F]DOPA) uptake K(i) values in the basal ganglia of nine smoking and 10 nonsmoking healthy men were measured with positron emission tomography. RESULTS Significantly higher [(18)F]DOPA uptake was observed in both the putamen (average 17.3% hi...

In anesthetized dogs and cats, intravenous L-dopa reduced the increase in mean blood pressure in response to bilateral carotid occlusion by 77.5% (P<0.01). In the presence of a dopa decarboxylase inhibitor (Ro 4-4602), this effect was absent. Transmission across the superior cervical sympathetic ganglion in the cat was unaltered by the administration of L-dopa. Carotid artery infusion in the do...

The cAMP response element-binding protein (CREB) is believed to play a pivotal role in dopamine (DA) receptor-mediated nuclear signaling and neuroplasticity. Here we demonstrate that the significance of CREB for gene expression depends on the experimental paradigm. We compared the role of CREB in two different but related models: l-DOPA administration to unilaterally 6-hydroxydopamine lesioned ...

3,4-Dihydroxyphenylalanine (Dopa) decarboxylase is a stereospecific pyridoxal 5'-phosphate (PLP)-dependent alpha-decarboxylase that converts L-aromatic amino acids into their corresponding amines. We now report that reaction of the enzyme with D-5-hydroxytryptophan or D-Dopa results in a time-dependent inactivation and conversion of the PLP coenzyme to pyridoxamine 5'-phosphate and PLP-D-amino ...

Gastric lipase (GL) plays an important role in emulsification and digestion of food fat. Lipids are components of the hydrophobic mucus and mucosa barrier. Damage of the gastric mucosa may therefore be related to changes in the lipid content and GL activity. In the present paper, we studied the effect of administration of a single dose of 96 % ethanol (E) and indomethacin 20 mg x kg(-1) (IND) o...

Introduct ion Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the most frequent neurodegenerative disorders and cause of disability among western societies.1 Interest in the selective inhibition of monoamine oxidase B (MAO-B) has increased in the last years due to their therapeutic potential in this age related neurodegeneration. Currently, acetyl cholinesterase (AChE) inhibitors are ...

Pix is a plant growth regulators thatinterfereswithotherhormones and affectthegerminationandgrowthof cotton.In thisstudythe effect ofdifferentconcentrationsof pix, namely, 0 (control),10, 20, 30and40 ppm on germination,radicledry weight, radiclelength,insolubleandsoluble sugarsandantioxidantenzymes activity (catalase, peroxidase and poly phenol oxidase) incottonseedling (Gossypium hirsutum L.cv...