Abstract"25I-Serum amyloid P component (SAP), injected intravenously into 10 normal subjects, remained predominantly intravascular with mean (SD) T112 (half time) in plasma of 24.5 (5.9) h. The fractional catabolic rate of 68 (19)% of the plasma pool per day was more rapid than other reported human plasma proteins. All radioactivity was excreted in the urine by 14 d. In 16 patients with monoclonal gammopathy or chronic inflammatory diseases, but without amyloidosis, 1251-SAP metabolism was normal. However, among 45 patients with biopsy-proven systemic amyloidosis (25, amyloid A type; 20, amyloid L type), 1251I-SAP was cleared from the plasma more rapidly, accumulated in the amyloid deposits, and persisted there. The T112 in amyloid, measured directly with '31I-SAP, was 24 d. Repeat studies after 6-18 mo were notably consistent in normals but changed significantly in amyloid patients, generally correlating with clinical signs of disease progression.

In 12 pregnant sows (Sus scrofa domestica), containing 144 live fetuses, placental blood flow was measured by the indicator fractionation technique using radioactive microspheres. In 8 of these litters, which contained 96 live fetuses, placental blood flow was obtained in absolute units. Significant positive correlations were observed between placental blood flow and placental weight, between placental blood flow and fetal weight, and between placental weight and fetal weight. It is clear that the runt, by comparison with his littermates, has a low birthweight in association with a small placenta and a low placental blood flow.

The reversal of the neuroleptanalgesic combination of fentanyl/fluanisone using mixed agonist/antagonist opioids has been investigated in the rabbit. All of the compounds studied (naloxone, nalbuphine, meptazinol, butorphanol, buprenorphine, pentazocine, doxapram) reversed the respiratory depression and sedation produced by fentanyl/fluanisone. Fentanyl/fluanisone produced profound analgesia for 180 min, which was rapidly and completely antagonized by naloxone. The mixed agonist/antagonist opioids produced a reduction in the degree of analgesia but, in contrast to naloxone, analgesic activity persisted from 120 min (meptazinol) to 420 min (buprenorphine). Administration of buprenorphine to rabbits anaesthetized with fentanyl/fluanisone and midazolam confirmed that the reversal of respiratory depression was accompanied by the return of arterial pH, PCO2 and PCO2 to preanaesthetic values. The use of neuroleptanalgesic anaesthetic regimens, which have been shown to provide effective surgical anaesthesia, combined with reversal using a mixed agonist/antagonist opioid to provide postoperative analgesia, appears to be a valuable refinement of current laboratory animal anaesthetic practice.

Six subspecialists with considerable experience in fetal ultrasound viewed a selection of pre-recorded ultrasound scans. Scans from 18 patients recorded on VHS video-tape were supplied from five centres in the UK and Ireland, each made on a high-resolution ultrasound machine by an experienced sonologist at a referral centre. Each observer viewed the scans on a large display monitor in an individual viewing booth. The scans were viewed in random order, at randomly selected bandwidths. Observers, who were blinded to both recording and bandwidth, assessed the technical quality on a five-point Likert scale. They also recorded their diagnosis. The six observers each carried out 32 viewing sessions, which gave a total of 192 viewings. There was no significant difference in the perceived technical quality of the scans between the two bandwidths used (P = 0.09). Of the 84 recordings transmitted at 1920 kbit/s, 71 (85%) were diagnosed correctly or 'half correctly' and 13 (15%) were misdiagnosed. Of the 95 recordings transmitted at 384 kbit/s, 66 (69%) were diagnosed correctly or 'half correctly' and 29 (31%) were misdiagnosed. This difference was significant (P = 0.03). The results indicate that although there were no perceived differences in technical quality between recordings transmitted at 384 or 1920 kbit/s, diagnostic accuracy was marginally worse at the lower bandwidth. This suggests that the higher bandwidth conveys more detail and information to the observer, which in turn enables more accurate diagnosis. However, further work is required before a definitive choice can be made about the optimum transmission bandwidth for remote fetal ultrasound studies.

The statistical distribution of birthweights in 64 litters of pigs, 48 litters of dogs, 59 litters of rabbits, 130 litters of rats and 46 litters of mice was examined. Birthweight followed a Gaussian or normal distribution in about two-thirds of the litters inspected, as judged visually using a normal probability plot, and by the W-test statistic. In the remainder, a single outlying observation in an otherwise normal sample was detected by Dixon's test, and/or a separate sub-population of low birthweight animals could be identified by fitting two normal populations to the observed samples. In the non-Gaussian litters, the average proportion of affected members was 40% of the litter. These results suggest that growth-retarded neonates should not be regarded simply as the tail-end of a normal distribution.