[Fundamental study of piperacillin sodium in term and premature neonates].

Piperacillin sodium (PIPC) is a semisynthetic penicillin displaying high antibacterial activities against Gram-positive and Gram-negative bacteria including Pseudomonas sp., Proteus sp., etc. It acts bactericidally and is stable against beta-lactamases. The usefulness of PIPC in the treatment of infections in mature and premature neonates was investigated and the following results were obtained. The pharmacokinetics (half-life, distribution volume, total body clearance) of PIPC after 50 mg/kg intravenous drip infusion in 10 cases of neonates were examined. Relationship between T1/2 and hours after birth was clearly determined. Adverse effects and abnormality in laboratory test values were not observed. It is considered from the above results that PIPC may be an useful antibacterial agent for the treatment of infections in neonates.

Intra-His bundle block following ligation of anterior septal artery in dog.

Intra-His bundle block was produced by ligation of the anterior septal artery in dogs. The duration of the His bundle potential was gradually increased following the ligation, and an obvious splitting of the His bundle deflection was observed thereafter. Finally, spontaneous second and/or third degree intra-His bundle block appeared. Before the development of spontaneous block, a pacing induced intra-His bundle block was observed when the duration of the His bundle deflection was prolonged approximately to twice the control value. Careful measurements of the intervals between two split His bundle deflections (H1-H2) in spontaneous as well as in pacing induced block revealed atypical Wenckebach periodicity in all analyzed periods except in one. Repeating and/or transient decreases of H1-H2 intervals were frequently observed as atypical findings.