924 TETRACYCLINE BLOOD-LEVELS
drawn, while the other 4 ate breakfast. Serum-tetracycline activity was determined by the agar-diffusion method with Bacillus cereus var. mycoides (ATCC 9634), using tetracycline was
U.S.P. as the standard. As shown in the accompanying table, adequate levels are obtained with 300 mg. of lymecycline b.d.; in addition there is the advantage of higher peaks of serum-antibiotic activity, after each administration, which are not greatly affected by meals. L. VITARTALI Ospedale Civile di Merate, A. PISANI-CERETTI. Como, Italy.
SUBJECTS AFTER 300 mg. b.d.
ORAL ADMINISTRATION OF
(L.H.) was measured by laboratory.2
F.S.H. and L.H. were measured on daily samples in six women, who were admitted to hospital for the study, in control cycles and cycles during which they received norethynodrel 2-5 mg. and mestranol 01mg. daily for 17-25 days beginning on the 2nd day of flow. In a typical normal menstrual cycle plasmaF.S.H. was significantly raised in the first half of the follicular phase, followed by a sharp midcycle peak of lesser magnitude than the L.H. peak; F.S.H. luteal-phase levels were significantly less than follicular levels (fig. 1). Similar results were seen in 21 normal menstrual cycles in the women. F.S.H. values in the control cycle of a second woman and in response to the oral
ORAL CONTRACEPTIVES AND FOLLICLE STIMULATING HORMONE our knowledge, the effects of oral contraceptives plasma-follicle-stimulating-hormone (F.S.H.) levels in women have not been reported, though Stevens et a1.l reported
decreased F.S.H. excretion in the urine after ethynodiol diacetate and mestranol. We report here the effects of an oral contraceptive on plasma-levels of F.s.H. measured by a double-antibody method of radioimmunoassay, using ’Reichert 780 ’ pituitary F.S.H. labelled with 131J and rabbit antihuman F.S.H. serum, with the International Reference Preparation, no. 2, of human menopausal gonadotrophin as reference standard. Luteinising hor1. Stevens, V. 14, 327.
C., Vorys, N., Besch, P. K., Barry, R. D. Metabolism, 1965,
Fig. 2-Plasma-F.S.H. in a second woman during a control cycle (on left), and in response to norethynodrel 25 mg. and mestranol 01 mg. daily, beginning on 2nd day of flow (on right).
contraceptive are shown in fig. 2. The early follicular rise and the midcycle peak were obliterated, and all values were comparable to the luteal-phase levels of the control cycle. The same response was seen in all six women receiving the contraceptive. The suppression of plasma-F.s.H. by norethynodrel and mestranol was similar to the previously reported suppression of plasma L.H.3 in the
Endocrinology Branch, National Cancer Institute, Bethesda, Maryland 20014.
C. M. CARGILLE G. T. Ross.
PROJECTIONS IN EOSINOPHILS SIR,-Nuclear projections (nuclear pockets or blebs) similar NUCLEAR
those described by Epstein and Achong4 have been found in several types of normal and abnormal cells of the blood, lymph-nodes, bone-marrow, and thymus, and in lymphoid, neutrophilic, and monocytic leucocytes-e.g., in thymocytes and Reed-Sternberg cells. It has been suggested that these nuclear features are a physiological structure in all forms of leucocytes,5and they have been described in immature bonemarrow granulocytes from patients on fluorouracil 6 or cytarabine hydrochlorideand from those with untreated pernicious anaemia,6 in peripheral-blood myeloblasts of treated
2. Odell, W. D., Ross, G. T., Rayford, P. L. ibid. 1966, 15, 287. 3. Ross, G. T., Odell, W. D., Rayford, P. L. Lancet, 1966, ii, 1255. 4. Epstein, M. A., Achong, B. G. J. natn. Cancer Inst. 1965, 34, 241. 5. Huhn, D. Nature, Lond. 1967, 216, 1240. 6. Stalzer, R. C., Kiely, J. M., Pease, C. L., Brown, A. L., Jr. Cancer,
Fig. 1—F.S.H. (solid line) and L.H. (interrupted line) in plasmasamples taken daily during a normal menstrual cycle in a representative woman.
N.Y., 1965, 18, 1071. Ahearn, M. J., Lewis, C. W., Campbell, L. A. Nature, Lond. 1967, 215, 196.