SUMMARY1. Transfer of fatty acids across the placenta was studied in anaesthetized rabbits at 28-days gestation by measuring umbilical venous-arterial differences, by injection of labelled palmitate into the mother and observing its appearance in the foetus, by injection of labelled palmitate into the foetus and measuring its appearance in the mother and the foetal clearance rate.2. The release of fatty acids and glycerol by foetal adipose tissues was investigated in vitro by measuring the effect of addition of noradrenaline to the incubation medium and in vivo by measuring the effect of noradrenaline infusion into the foetus on circulating glycerol and free fatty acid concentrations.3. In anaesthetized rabbits at 28-days gestation the maternal circulating free fatty acid concentrations were high and there was a positive umbilical venous-arterial difference. High maternal free fatty acid concentrations were associated with high umbilical venous-arterial differences.4. Label was present in the foetus in 2 min and reached a peak in 3 min after injection of labelled palmitate into the mother. Label appeared in the maternal circulation in 1 min after injection into the foetus. The half-life of labelled palmitate was of the order of 30-60 sec in both mother and foetus.5. Foetal white adipose tissue released both free fatty acids and glycerol into the medium and the rate of release increased four to five fold after addition of noradrenaline. Infusion of noradrenaline in the foetus led to a rise in glucose and glycerol concentrations, but the change in free fatty acid concentrations was not significant.6. It was concluded that (i) free fatty acids can cross the rabbit placenta in amounts sufficient to provide the fatty acid components of stored 30 M. C. ELPHICK, D. G. HUDSON AND D. HULL triglyceride and structural lipids; (ii) placental transport of free fatty acids depends in part on maternal blood concentration and on foetal uptake; (iii) foetal circulating free fatty acids are continually exchanging with fatty acid pools in the placenta and with the maternal circulating free fatty acids.

Fetal rabbits were obtained by Caesarian section from 28-day pregnant does which had been fasted for 48 h (days 26–28). Organ weights, fat contents and blood metabolite levels were compared with a group obtained in a similar manner from non-fasted does. Similar data were obtained for term fetuses (31 days) born by natural delivery. In 28-day pregnant, fasted does, blood levels of free fatty acids (FFA) and glycerol were doubled compared with non-fasted controls. Fetal levels showed a similar increase. Both groups of fetuses from fasted does had increased fat stores both in the liver and adipose tissue. The overall increase in fat stores was 80–100%. It is suggested that during maternal fasting increased amounts of maternal FFA cross the placenta into the fetal circulation and are incorporated into the fetal fat stores.

The influence of age and sex has been evaluated in 326 allergic patients on the following parameters: total serum IgE concentration, serum concentration of specific IgE antibodies against seventeen common allergens, mean number of positive allergens, absolute numbers of circulating eosinophils, corticosteroid dependence and response to sodium cromoglycate (DSCG). The results indicate that age and sex significantly influence the IgE antibody production in these patients. The data strongly suggests the appearance during ageing of a progressive natural desensitization. This contrasts with the increased frequency of corticosteroid-dependent cases during ageing. There is an inverse relation between age and response to DSCG therapy.

(1) Fetal rabbits of different gestational ages (20–29 days) were obtained by Caesarian section and term rabbits (31 days) by natural delivery. After dissection, organ weights were obtained and growth curves drawn. Brown adipose tissue was first visible at 22 days gestation and increased relatively more quickly than the body weight till day 26 after which it formed a constant percentage of the body weight. Growth of white adipose tissue followed a similar pattern, except that it was not visible until day 24. (2) The percentage triglyceride content of both types of adipose tissue increased throughout the latter part of gestation. (3) Fetuses of low birth weight had depressed fat stores in brown adipose tissue. Some, but not all, of the high birth weight fetuses had relatively enlarged fat stores. It is suggested that the conditions which produce fetuses of unusually low or high birth weight tend to have a greater corresponding effect on the fetal fat stores.

Background Greyhounds have several hematologic variables that are outside of the respective reference intervals of other dog breeds. In addition, increases in HCT, total protein and HGB concentration, and RBC and WBC counts occur immediately after exercise; these values return to resting values within a few hour after racing. Objective This study evaluated the effects of exercise on the concentration of reticulocytes in circulating blood in racing Greyhounds. We hypothesized that reticulocyte numbers are significantly increased immediately after a race, and return to baseline within one to 2 h postrace. Methods Fifty actively racing Greyhounds at the Wheeling Island Racetrack and Casino were included in the study. Samples were collected by jugular venipuncture one day prior to racing at the kennel (resting), immediately after racing, and one to 2 h after the race (recovery). Reticulocyte counts were determined with an IDEXX ProCyte Dx Hematology Analyzer (IDEXX Laboratories, Inc., Westbrook, ME, USA). Due to a nonparametric distribution, the results were statistically compared using the Friedman test. Results Reticulocyte concentrations were significantly different among the 3 sample collection times (P < .0001). There was a significant increase in reticulocyte concentration immediately after racing (P < .001); one to 2 h after racing, the reticulocyte numbers decreased significantly (P < .001) to counts comparable to resting samples. Conclusion The increase in reticulocyte concentration is probably related to splenic contraction secondary to the release of catecholamines, although premature bone marrow release could also account for these changes. Thus, it is important to consider a Greyhound's activity and degree of excitement when interpreting selected hematologic data in a clinical setting.