Cognitive effects attributed to angiotensin II may result from its conversion to angiotensin IV.

This study tests the hypothesis that the facilitation of learning and improvement of memory observed after an intracerebroventricular (i.c.v.) injection of angiotensin II (Ang II) is, in fact, caused by its derivative angiotensin IV (Ang IV). We ran two memory tests as well as an auxiliary test assessing motor performance in rats injected (i.c.v., 1 nmol in 2 microl saline) with Ang II or Ang IV. There were separate groups receiving peptide or saline five, 10 and 15 minutes before testing. Ang IV significantly increased step-through latencies in a passive avoidance paradigm as well as improved discrimination between familiar and unfamiliar objects in an object recognition test in all groups showing better retrieval of memory of aversive as well as appetitive stimuli in the peptide-treated groups regardless of the time of its injection. In contrast, rats treated with Ang II demonstrated significant improvement of memory of aversive and appetitive stimuli in the same tests only 15 minutes after its i.c.v. injection, with no effect in the groups injected five minutes before testing and slight efficacy in those injected 10 minutes before the test. Numbers of crossings, rearings and bar approaches in an open field were similar both in the peptide-treated and control groups making it unlikely that changes in motor performance affected the memory tests. In line with the present views on the intracellular metabolism of Ang II, these results suggest degradation to Ang IV by aminopeptidases A and N is necessary before the cognitive effects can occur.     

Vacuolar degeneration of the cochlea in young rats

In the course of investigations of the post-natal development of the ear in Sprague-Dawley rats, a hitherto unrecorded degenerative process was seen in two animals (7-and-8-days old). The process was characterized by vacuolization of almost all the cellular elements of the cochlear tissues. The overall shape and size of the cochlear structures remained well preserved. The organ of Corti did not atrophy but its components were vacuolized, as well as the cells of other inner ear tissues, except for nuclei in the lower part of the modiolus.     

Femoral and iliac vein stenoses after prolonged femoral vein catheter insertion.

BACKGROUND/AIMS: Catheterization of the femoral vein is a safe and recommended method of temporary access for haemodialysis. In some patients, however, because of the lack of other possibilities, it is necessary to maintain long-term femoral cannulation. The aim of the study was to evaluate the frequency of stenosis after prolonged femoral cannulation. METHODS: The 24 patients incorporated in the study were divided into two groups. Group 1 consisted of 10 end-stage kidney failure patients (four females and six males, aged 32-75 years, average 55.6+/-13.6 years) in whom femoral catheters were maintained for less than 2 weeks (5-14 days, average 9.3+/-3.6 days). Group 2 included 14 chronic haemodialysis patients (six females and eight males aged 23-65 years, average 49.5+/-13.27 years). The time of catheter maintenance ranged from 2 to 16 weeks (average 6.4+/-4.2 weeks). Femoral and iliac vein status was evaluated using magnetic resonance imaging. RESULTS: A feature of venous stenosis of both the femoral and iliac veins was disclosed in four patients in whom femoral cannulation lasted more than 4 weeks. There were no stenoses in group 1. CONCLUSION: Long-term femoral cannulation for more than 4 weeks may be associated with a significant risk of stenosis in the femoral and/or external iliac veins.