No abstract

In a previous publication in this series, Duff and McMillan (1) made a comparison of the effects of cholesterol feeding in normal rabbits and in rabbits rendered persistently diabetic by means of alloxan. It was found that in the two groups of animals hyperchotesterolemia of comparable degree was induced b y the feeding procedure. Nevertheless, the severity of the atherosclerosis of the aorta produced in the diabetic rabbits was much less than in the non-diabetic controls. Only two factors were observed to be consistently associated with this inhibition of the expected morphological effects of cholesterol feeding; namely, the diabetic state and a degree of visible lipemia considerably greater than that observed in the control animals. Because of the occurrence of this greater degree of visible lipemia in the diabetic rabbits, it was thought likely that a study of the main serum lipids, rather than of cholesterol alone, might serve to elucidate the mechanJ.qm of the inhibition of cholesterol atherosclerosis in the alloxan-diabetic rabbit. In this paper, such a study is presented. The findings have already been briefly recorded (2).The llpids of the serum are insoluble in water; nevertheless they are present in the blood serum, an aqueous medium, which normally is clear and limpid. It is obvious, therefore, that there must be some mechanism whereby they are held in suspension in the serum. It is equally obvious that, when this mechanism becomes upset to a greater or lesser degree, then the colloidal stability of the lipids in the serum is impaired. From the study of the lipids in both normal and pathological sera, it has become evident that the serum lipids, as a group, exhibit two important features. In the first place, the different lipid components are known to show an interrelationship which is more constantly maintained and, therefore, of more significance than the concentration of any single component (3). Secondly, there exists a close association between the * This work was assisted by grants-in-aid from the National

Norepinephrine (NE) and serotonin (5-HT) concentrations were determined in three areas of the rat brain following 8 wk exposure to differing physical activity and dietary regimens. Animals were divided into sedentary and exercise groups, and one-half of each received either a normal or atherogenic diet. The exercise consisted of 30 min of treadmill running, 5 days/wk, for 8 wk. Brains were weighed and sectioned into cerebral cortex, cerebellum, and remainder (midbrain), and fluorometrically analyzed for NE and 5-HT content. In most brain areas, NE and 5-HT levels were significantly greater among exercise-normal diet and exercise-fat diet compared to both sedentary groups. In the cerebral cortex, exercise-normal diet rats possessed higher levels of NE and lower concentrations of 5-HT than sedentary animals. The atherogenic diet did not affect amine levels other than 5-HT in the cortex among exercise rats. The NE results are consistent with prior research indicating its control of sympathetic function. Increased levels of 5-HT in the midbrain may be the neurotransmittal adaptation responsible for decreased appetite and enhanced weight loss following chronic endurance exercise.

In Ebstein's anomaly the tricuspid valve is displaced downward so that the upper portion of the right ventricle is incorporated in the right auricle. This imipairs the efficiency of the right side of the heart and produces a distinctive syndrome, which is described here for the first time. Diagnosis is important because this malformation, which is not amenable to surgery, may be confused with the tetralogy of Fallot.