Sera from young laying chickens, found to be hypertriglyceridemic by serum lipid and lipoprotein analyses, were fractionated by ultracentrifugation into very low ( d < 1.006 g/mL) and low density ( d 1.006-1.063 and 1.024-1.045 g/mL) lipoproteins (VLDL and LDL). The purity of these lipoprotein fractions was evaluated by electrophoretic, immunological, and electron microscopic techniques; their chemical and physical properties were subsequently determined and compared with those of the corresponding human fractions. While an overall resemblance was evident between each chicken fraction and its human counterpart, minor differences were detected in surface charge, chemical composition, and particle size. Both chicken VLDL and LDL exhibited lo\v surface charge upon electrophoresis; the triglyceride content and particle size of the chicken LDL fractions were greater than those of the corresponding human preparations. Immunological studies revealed a partial identity between the VLDL and between the LDL of chicken and man; quantitative microprecipitation showed the cross-reactivity of chicken and human LDL to amount to about 10%. The chicken lipoproteins possessed a common antigenic determinant and reacted strongly to an antiserum to human apolipoprotein B. The presence of an apolipoprotein B like component in chicken VLDL and LDL was confirmed by sodium dodecyl sulfate-

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In this study, we investigated the usefulness of the determination of evening urinary free corticoids/ creatinine in samples collected from 20.00 to 24.00 h as a screening test in Cushing's syndrome. In controls (N = 61) the ratio values ranged from 1.1 to 9.4 \g=m\mol/mol,whereas in patients with Cushing's syndrome (N = 20), they ranged from 27.5 to 855.5 \g=m\mol/mol. However, in 28% of patients with major obesity (> 50% overweight) and no hypercortisolism, the ratio values were between 9.4 to 27.8 \g=m\mol/mol. A short (10 days) hypocaloric diet induced a decrease in the values in 75% of these patients; the normal range was reached in 50% of them. In addition, the evening urinary free corticoids/creatinine was slightly abnormal in 8 out of 10 patients with incidentally discovered 'silent' adrenal adenomas, whereas it was normal in all 6 with other adrenal masses. In conclusion, evening urinary free corticoids/creatinine is easy to obtain and it reaches a higher sensitivity (100%) and specificity (97%) than the 24 h urinary free corticoids. In the case of borderline values, the presence of overweight should be taken into account.