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A Huberman

Publications and source records attributed to A Huberman.

33 records · Page 2Linked to original sources
PubMed1977

Release of a neurodepressing hormone from the crustacean sinus gland.

The nervous system of the crayfish contains a peptide of low molecular weight which depresses the spontaneous electrical activity of motoneurons in the abdominal ganglia. Most of this substance is contained in the sinus gland, a neurohemal organ in the eyestalk. Electrical stimulation of the isolated sinus gland, or its incubation in potassium-rich solutions (20--80 mM) results in the release of the neurodepressing peptide. The release is calcium-dependent and appears to involve a process of exocytosis. The released product shows electrophoretic properties undistinguishable from the substance present in the sinus gland.

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PubMedDate not supplied

Secondary structure of a crustacean neuropeptide hormone family by means of CD.

Three hormonal neuropeptides have been purified from the sinus gland of the Mexican crayfish Procambarus bouvieri by means of a single-step HPLC method: The molt-inhibiting hormone (MIH) and two isoforms of the crustacean hyperglycemic hormone (CHH-B and CHH-C). Compositional analysis and partial characterization of three neuropeptides revealed such a high degree of homology that we consider them to be members of a family. Circular dichroic spectra of the three neuropeptides showed that the secondary structure of both isoforms of the CHH are very similar, but that there are important differences in secondary structure between MIH and the CHHs, especially in helix content and in disordered regions.

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PubMedDate not supplied

Primary structure of the major isomorph of the crustacean hyperglycemic hormone (CHH-I) from the sinus gland of the Mexican crayfish Procambarus bouvieri (Ortmann): interspecies comparison.

The amino acid sequence of this neuropeptide was elucidated by means of a combined approach of enzymatic digestions, manual and automatic Edman degradations, and mass spectrometry. It is a 72 residue peptide (molecular mass 8388 Da), with six cysteines forming three disulfide bridges connecting residues 7-43, 23-39, and 26-52, with blocked N- and C-termini, and lacking the amino acids histidine, methionine, and tryptophan. The CHH-I of Procambarus bouvieri is compared with the other known CHHs from Orconectes limosus (98.6% identity), Homarus americanus isomorph A (83.3% identity), Homarus americanus isomorph B (79.2% identity), and Carcinus maenas (61.1% identity).

Amino Acid Sequence↗
PubMedDate not supplied

[Chronology of portal hypertension, decreased sodium excretion, and activation of the renin-angiotensin system in experimental biliary cirrhosis].

OBJECTIVES: 1) To evaluate the biochemical, renal, histological and splanchnic and systemic hemodynamic abnormalities induced by bile duct obstruction in rats, and 2) to study the temporal relationships between the start of portal hypertension, decrease of urinary sodium excretion and activation of the renin-angiotensin system. METHODS: Bile duct obstruction was induced in 127 male Wistar rats, and renal function, hemodynamic, biochemical and liver histology were evaluated at weeks 1, 2, 3 and 4 after complete bile duct obstruction; the data were compared to that in 30 control rats. RESULTS: Portal pressure significantly increased at week 1 (11.7 +/- 1.5. vs. 7.8 +/- 1.5 mmHg, p < 0.05) while the mean arterial pressure remained stable until week 4 when a slight decrease was observed (91.3 +/- 6.6 vs. 96.1 +/- 8.6 mmHg in control rats). A significant decrease in urinary sodium excretion was observed at week 1 (1.1 +/- 0.5 mEq/24 h) compared to control rats (2.3 +/- 0.6 mEq/24 h). In addition, hyperreninemia was observed at week 1 (5.1 +/- 0.2 vs. 2.4 +/- 1.3 ng Ang l/mL/h, p < 0.05) and hyperaldosteronism at week 2 (103 +/- 46 vs. 25.1 +/- 8.8 ng/24 h, p < 0.05) compared to control rats. CONCLUSION: A temporal relationship between the beginning of portal hypertension and a decrease of renal sodium excretion, hyperreninemia and hyperaldosteronism was observed in bile duct ligated rats. This experimental model could be used to evaluate the effects of new drugs to prevent biliary cirrhosis including the abnormalities in the renal handling of sodium.

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