α-HUMAN ATRIAL NATRIURETIC POLYPEPTIDE REDUCES THE PLASMA ARGININE VASOPRESSIN CONCENTRATION IN HUMAN SUBJECTS

The synthetic alpha-human atrial natriuretic polypeptide (alpha-hANP) was infused into six normotensive, euvolaemic, healthy volunteers to examine the effect on the plasma arginine vasopressin (AVP) concentration. The intravenous administration of alpha-hANP (0.1 microgram/kg/min, 20 min) led to a remarkable reduction in mean blood pressure (-10 mmHg, P less than 0.05), and there was an increase in pulse rate (+10 bpm, P less than 0.05), in each subject. The urinary volume, sodium excretion and cyclic 3',5'-guanosine monophosphate (cyclic-GMP) excretion were increased to 3.5 (P less than 0.05), 2.5 (P less than 0.05) eight-fold (P less than 0.01), respectively, during the alpha-hANP infusion. The dose and duration of the synthetic alpha-hANP in the present study was sufficient to induce these cardiovascular and renal effects. The plasma AVP concentrations decreased from 0.39 +/- 0.09 pg/ml to the undetectable level during the alpha-hANP administration. After infusion, the plasma concentrations of the AVP promptly returned to preinfusion levels (0.46 +/- 0.14 pg/ml). However, there was no significant change in plasma AVP concentration during placebo infusion. The marked suppression in plasma AVP concentration may account for the remarkable diuresis, in addition of the direct renal effects of the synthetic alpha-hANP.     

HYDROGEN-TRITIUM EXCHANGE TITRATION OF THE HISTIDINE RESIDUES IN BOVINE HEART CYTOCHROME C AND ANALYSIS OF THEIR MICROENVIRONMENT

Microenvironments of the three histidine residues located at the positions 18, 26, and 33 from the amino terminus in bovine heart cytochrome c were analysed in solution by the hydrogen-tritium exchange titration method, which has been developed in this laboratory. Histidine-18, which is liganded to the heme iron, and histidine-26 did not incorporate tritium in native state, indicating that the two are located in solvent inaccessible hydrophobic regions. Histidine-33 was labeled with tritium to an appreciable extent and seemed to be partially buried in the molecule. The pKa value estimated for histidine-33 was 6.1 at 37° by the tritium exchange titration, suggesting that the residue interacts very weakly with a neighboring cationic group. These results seem to be compatible with the tertiary structure of the protein deduced from the X-ray crystallographic analysis.     

Fetal Inclusion: Report of Two Cases and Review of the Literature and Diagonostic Criteria

ABSTRACT  Two cases of fetal inclusion were presented and 27 cases ever reported in Japan were reviewed. The first case presented had placental component and highly differentiated visceral organs in addition to the vertebral column and skin covering the included mass. The second case also had vertebral column and skin but the organoid pattern was not so clear as seen in the first case. It was most important to differentiate included fetus from teratoma in this second case and in some cases reviewed here, in which an orderly arranged visceral organ was not noted. Thus, diagnostic criteria described by Ohkawa et al was revaluated on the basis of embryological consideration and then it was concluded that included fetus could be diagnosed only by the presence of vertebral column and skin covering the included mass. Finally, it is proposed that fetal inclusion may be regarded as an acardiac structure embodied in the autosite.     

An Unusually Mild Variant of Hunter's Syndrome in a 14-Year-Old Boy Normal Growth and Development

An unusually mild variant of Hunter's syndrome was described in a 14-year-old Japanese boy. He has maintained normal growth (25th percentile on the growth curve), and development (IQ 120-130) until 14 years and 4 months of age.