Recombinant human inhibin A and recombinant human activin A regulate pituitary and ovarian function in the adult female rat.

The roles of recombinant human inhibin A (rh-inhibin A) and rh-activin A in regulating the pituitary and ovary of the adult female rat were examined. Serum and pituitary FSH and LH and serum estradiol and progesterone concentrations were evaluated at 1, 2, and 6-12 h after sc hormone administration on metestrus and on proestrus. A second study examined the effect of the hormones 24 h after injection at 1000 h on each day of the cycle. Rh-inhibin A inhibited FSH secretion 60 min after injection on proestrus but did not alter serum FSH concentration on metestrus. FSH remained low for the 12 h examined during the evening of proestrus and on the morning of estrus. Serum LH concentration, pituitary FSH content, and pituitary LH content were not significantly changed under any experimental condition. Rh-inhibin A did not regulate estradiol concentration on metestrus or on proestrus; however, it did cause a rise in serum estradiol in animals treated on metestrus and diestrus and examined 24 h later. This suggests that inhibin may participate in regulating follicular maturation in a subset of developing follicles. Last, after rh-inhibin A treatment, the duration of the proestrus progesterone surge was shortened. Serum FSH concentration rose by 6 h after rh-activin A administration on proestrus and both FSH and LH rose by 6 h after hormone administration on metestrus. Rh-activin A significantly increased serum estradiol through 6 h of treatment on proestrus. Progesterone levels were significantly greater in animals treated on metestrus and killed 24 h later. The increased length of the midcycle progesterone surge may be the result of increased LH on metestrus. These studies suggest that rh-inhibin A and rh-activin A may regulate ovarian and pituitary function in a cycle dependent manner. Specifically, rh-inhibin A can acutely regulate FSH and progesterone on proestrus and estradiol during follicular development. Rh-activin A acutely regulates FSH on both proestrus and metestrus and LH on metestrus. Whether circulating endogenous inhibin or activin participate physiologically in these functions is under investigation.

Comparisons of indicatrices of desert and urban areas obtained from Landsat MSS data.

The indicatrices of ground glass surfaces were obtained as a measurement of their roughness and expressed by the Minnaert constant k. The indicatrices were also obtained for downtown areas of San Francisco and Berkeley and the desert areas in Nevada and California by using Landsat multispectral scanner (MSS) data with varying Sun elevations. The values of k for each training area were obtained. Finally the biconical spectral reflectance of sand collected from the desert of the training areas was measured in the laboratory, and the computed values of k were compared with those derived from the Landsat MSS data.

Inhibin and activin locally regulate rat ovarian folliculogenesis.

The role of inhibin and activin in the initiation of follicular development, growth, and atresia was examined. Human recombinant inhibin (1 microgram) was unilaterally injected into the ovarian intrabursal space of 25-day-old rats. The contralateral ovary served as a control. Recruited growing follicles (350-500 microns) were observed 24 h after injection. The accumulation of follicles was greater in the inhibin-treated ovaries than in contralateral control ovaries. Moreover, the size distribution of the follicles was similar to the distribution of follicles recruited by systemic exogenous PMSG treatment. The effect of inhibin plus PMSG on follicular development was not different from that of PMSG treatment alone. Injection of human recombinant activin (1 microgram) into the ovarian bursa caused follicular atresia. Activin therapy blocked the follicular development caused by PMSG treatment. The effect of inhibin and activin on follicular development was further characterized by measuring the incorporation of [3H]thymidine into dividing cells. Inhibin enhanced follicular thymidine incorporation, while activin decreased granulosa cell proliferation. Furthermore, receptors for inhibin-A (6.4 x 10(3) receptors/cell) and activin-A (2.3 X 10(4) receptors/cell) were identified on granulosa cells. The evidence suggests that inhibin and activin act in a paracrine manner to regulate follicular development, inhibin as a follicular growth signal and activin as an atretagenic signal.

The influence of alcohol and tobacco on the components of choice reaction time.

In smokers a low dose of alcohol slightly improved decision time on a choice reaction-time task and in combination with tobacco resulted in significant improvement compared with placebo conditions. In nonsmokers decision time deteriorated significantly after a moderate dose of alcohol but not in smokers. The results are attributed to the stimulant action of a smoking dose of nicotine interacting with low levels of alcohol.

Infrared spectral emittance in geological mapping: airborne spectrometer data from pisgah crater, california.

Measurements of spectral emittance in the infrared region from 6.8 to 13.3 micrometers were made with an airborne spectrometer at a rate of six spectra per second, on flights 650 meters above the olivine basalt flows at Pisgah Crater in the southern Californian desert. The spectra show chemical and mineralogical differences that can be related to differences in the terrain below the aircraft.