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IT WAS SHOWN in a previous report from this laboratory (Meyer, McShan and Erway, 1945) that the ovaries of pregnant and pseudopregnant rats were high in succinic dehydrogenase (SDH-ase) and that this high activity was due to the lutein tissue rather than the other ovarian tissues. However, the determinations during pregnancy were made on days 18 and 20 of gestation, and therefore information is not available as to the way in which this enzyme changes in activity throughout pregnancy and lactation. Thus it was of interest to determine the SDH-ase activity of the corpora lutea and other ovarian tissues at intervals during these two phases of the reproductive cycle. The results obtained are presented in this report. EXPERIMENTAL Sprague-Dawley rats approximately 4 months of age were used in the study. Males were introduced into cages containing females on the day preceding the next estimated estrus and the females were examined on the following morning to determine whether insemination had taken place.

IT IS WELL KNOWN that the adenosine triphosphate system occupies a key position in the energy exchanges of muscle during glycolysis. The presence of ATP and the ATP-splitting enzyme, ATP-ase, in variable quantities in a number of additional tissues has been reported (DuBois and Potter, 1943), and evidence has been presented pointing to the ATP system as a unique mechanism in linking the energy-requiring reactions of tissues with the energy-yielding reactions (Potter, 1945). These reports suggested that the energy changes occurring in tissues other than muscle might be mediated through the ATP system. We became interested, therefore, in determining whether or not the ATP-ase activity of ovarian tissues varied during the different phases of the reproductive cycle, as it is well known that these tissues undergo rapid changes in function and structure at these times. The studies which are reported here were made on the ATP-aee activity of lutein and remaining ovarian tissues during the reproductive cycle. A p...

SINGER (1) AND BARRIE (2) have presented data which indicated that vitamin-Edeficiency has an influence on the histology of the thyroid gland. The former described a hypoplasia of the thyroid of 12 to 18-month E-deficient female rats, and the latter a hypoplasia of the thyroid of both E-low mothers and young born to them. The results of Singer and Barrie have been questioned by Telford, Emerson and Evans (3), who reported that they could find no evidence of hypothyroidism in E-low female rates or in young born to them. We have previously reported (4) that the weight of the thyroids of male rats deficient in vitamin E for 6 months or more was approximately twice that of normal controls, whereas the weight of thyroids from female E-deficient rats was not significantly different from that of normals in any of the age groups studied

Dogs were exposed to hypocapnia, hypoxemia with hypocapnia, and hypoxemia without hypocapnia for 30 minutes, then decapitated. Three hours later brain samples of white matter from the corona radiat...

Summary Methoxychlor did not appear in measurable amounts in the blood, milk or tissues of six dairy cows consuming alfalfa hay that had been dusted in the field with methoxychlor. Two cows receiving untreated alfalfa hay likewise had no methoxychlor in their milk, blood or tissues. There was no effect on milk or butterfat production or on feed consumption as a result of feeding methoxychlor-treated hay. The methoxychlor residue on the hay was 0, 7, 9.5 and 14 ppm. for the alfalfa treated with 0, 1, 2 and 2.8 lb., respectively, of methoxychlor per acre. There was no apparent effect of consuming the methoxychlor-treated hay upon the health of the cows. Good economic control of alfalfa weevil larvae was obtained in the plots of alfalfa dusted with methoxychlor. The treated plots gave a somewhat greater yield of hay than the untreated plots.

IN PREVIOUS quantitative studies from this laboratory it has been shown that the ovarian response of the non-castrated partner of parabiotic rats is a sensitive and reliable indicatorof the quantity of gonadotropic hormone released into the circulation of the rats by the pituitarygland of the castrated partner. It was demonstrated that crystalline estrone (1), estrin from theamniotic fluid of cattle (2) and testosterone, testosterone propionate and dehydroandrosterone (3)were effective in preventing the hypersecretion of gonadotropic hormone that occurs following castration of either male or female rats. When progressively greater quantities of the gonadal hormoneswere injected into the castrated partner the size of the ovaries of the normal partner was progressively decreased. If sufficient hormone was injected the ovaries were no larger than those of non-castrated controls.

SummaryThe ATP-ase activity and weight of lutein and ovarian tissue were determined during estrus, diestrus, pseudopregnancy, pregnancy and lactation. The results indicate that in general the enzyme activity per unit weight is lower in functional corpora lutea than in apparently non-functional corpora. The weight and enzyme activity per corpus luteum increased and decreased at approximately the same rate during pregnancy and lactation. The enzyme activity of ovarian tissue remaining after the removal of the corpora lutea was greatest on the 4th day of pseudopregnancy, 7th day of pregnancy and 11th day of lactation.

The concentration of lactic acid, sodium, potassium and calcium was measured in four structures of the brain 3 hours after death in anesthetized and unanesthetized dogs which had been subjected to simulated altitude and ground level control protocols for 15 minutes. The effect of the simulated altitude was elevation of a) the sodium concentration in the corona radiata but not in the cerebral cortex or caudate nucleus, b) the calcium concentration in the cortex, corona radiata and caudate nucleus and c) the lactic acid concentration in all the tissues. No potassium changes were noted. The effect of the anesthesia was very slight and only indirectly detectable. The sampling problem was studied and caudate nucleus and cortex recommended as sampling sites for the detection of hypoxia by lactic acid elevation if a whole hemisphere cannot be used. It is pointed out that accuracy in diagnosing ante mortem hypoxia depends upon discrete anatomical sampling since lactic acid is not evenly distributed within the brain. A chemical approach to give compensation for the uneven distribution of lactic acid is presented.

The lactic acid concentration of brain was measured 3 hours after death in dogs which had been subject to hypocapnia, hypoxemia with hypocapnia, and hypoxemia without hypocapnia for 15 minutes. There was no elevation of brain lactic acid above the control level in those dogs subjected to hypocapnia or hypoxemia alone, however, when hypocapnia and hypoxemia were combined there was a significant increase. Cardiovascular and blood chemical analyses support the conclusion that variations in cerebral blood flow, availability of oxygen at the tissue level and interference with oxidative metabolism are important determining factors in brain lactic acid build-up. The results agree with those obtained in altitude-exposed animals, for they likewise show an elevation of brain lactic acid.

SummaryIn this study, adrenalectomy prevented a rise in lactic acid content of brain tissue in hypoxic rats. When various adrenal hormones were injected, the brain lactic acid level of adrenalectomized hypoxic rats was elevated to the same extent as intact hypoxic rats. Animals adapted to a simulated altitude of 18,000 feet did not respond to the same degree as non-adapted animals when both groups were exposed to severe hypoxia.