Biochemical and biophysical research communications
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Biochem. Biophys. Res. Commun. · Oct 2003
Identification of urotensin II-related peptide as the urotensin II-immunoreactive molecule in the rat brain.
Urotensin II (UII) has been reported as the most potent known vasoconstrictor. While rat and mouse orthologs of UII precursor protein have been reported, only the tentative structures of UII peptides of these animals have been demonstrated, since prepro-UII proteins lack typical processing sites for their mature peptides. In the present study, we isolated a novel peptide, UII-related peptide (URP), from the extract of the rat brain as the sole immunoreactive substance to anti-UII antibody; the amino acid sequence of the peptide was determined as ACFWKYCV. cDNAs encoding rat, mouse, and human precursor proteins for URP were cloned and revealed that the sequences of mouse and human URP peptides are the same as that for rat URP. ⋯ URP was found to bind and activate the human or rat UII receptors (GPR14) and showed a hypotensive effect when administered to anesthetized rats. These results suggest that URP is the endogenous and functional ligand for UII receptor in the rat and mouse, and possibly in the human. We also describe the preparation of specific monoclonal antibodies raised against UII peptide and the establishment of a highly sensitive enzyme immunoassay system for UII peptides.
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Biochem. Biophys. Res. Commun. · Oct 2003
ReviewNew patterns of inheritance in mitochondrial disease.
With the identification of a patient with mutated mitochondrial DNA (mtDNA) of paternal origin, it has been unequivocally proven that not only does paternal mtDNA survive in the zygote, but it can also contribute substantially to the mtDNA pool of adult, human skeletal muscle. The questions are: how often does paternal mtDNA inheritance occur and what mechanisms are involved? In this paper, we will review current knowledge on the fate of sperm mitochondria after fertilization and discuss the impact paternal inheritance may have on our understanding of mitochondrial biology.
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Biochem. Biophys. Res. Commun. · Oct 2003
Biphasic action of midazolam on GABAA receptor-mediated responses in rat sacral dorsal commissural neurons.
The effect of the benzodiazepine agonist midazolam on gamma-aminobutyric acid(A) (GABA(A)) receptor-mediated currents was investigated in neurons acutely dissociated from the rat sacral dorsal commissural nucleus (SDCN) using the nystatin-perforated patch-recording configuration under voltage-clamp conditions. Midazolam displayed a biphasic effect on GABA responses. Low concentrations of midazolam (1nM-10 microM) reversibly potentiated GABA (3 microM)-activated Cl(-) currents (I(GABA)) in a bell-shaped manner, with the maximal facilitary effect at 0.1 microM; whereas at higher concentrations (above 10 microM), midazolam had an antagonistic effect on I(GABA). ⋯ The benzodiazepine receptor antagonist, flumazenil, abolished the facilitary effect of low concentrations of midazolam rather than the antagonism of I(GABA) induced by high doses of midazolam. In addition, activation of protein kinase C prevented the inhibitory effect of midazolam at higher concentrations, but did not influence the effect of midazolam at low concentrations. These results indicate that midazolam interacts with another distinct site other than the central benzodiazepine receptors on GABA(A) receptors as an antagonist at higher concentrations in SDCN neurons.