Lipotropic effect of estradiol-17 beta in fed and fasted lactating cows

The lipotropic effect of estradiol-17 beta was measured in seven nonpregnant Holstein-Friesian cows 2 to 5 wk into lactation. The experiment was divided into an initial 3-day control period, 19 days treatment, and 2 days fast. Jugular blood samples were taken twice daily during the control period, the last 2 days of treatment, and the fast. After the control period, four cows received daily injections of estradiol-17 beta benzoate (15 mg) in sesame oil for the remainder of the experiment whereas three cows received injections of sesame oil only. Estradiol-17 beta did not change triglyceride concentration of plasma during the treatment period but increased it markedly during fast. Estradiol-17 beta increased the free glycerol concentration of plasma during treatment. Cholesterol concentrations of plasma showed a consistent trend lower in the estradiol group during treatment and fast. No differences were apparent in glucose and blood ketone concentrations. The concentration of insulin in plasma was lower for the estradiol group during treatment. Estradiol-17 beta appears to have a similar effect on lipid metabolism in dairy cows to other species. However, it exerted a strong lipotropic effect only under fasting.

Spectroradiometric calibration techniques in the far ultraviolet: a stable emission source for the Lyman bands of molecular hydrogen

The problems associated with making accurate spectroradiometric measurements in the far uv region are sketched briefly. The equipment and methods that were developed for providing absolute sensitivity calibration of an Apollo 17 far uv spectrometer are described. The absolute reference standards were photoelectric diodes calibrated at the National Bureau of Standards. A complete vacuum optical facility, which included a premonochromator and stable uv light sources, was developed to calibrate the Apollo 17 instrument, and it has been used for a number of other tasks. Absolute radiometric calibrations between about 1200 A and 1700 A were performed with an absolute accuracy of +/-10%. The light source, which was designed to provide a very stable light output, is a low-pressure molecular hydrogen lamp in which the pressure is stabilized by thermal control of uranium hydride powder. Individual emission lines of the Lyman molecular band system of H(2) are used for calibration purposes. The lamp also copiously emits the 1215.7-A line (Lyalpha) of atomic hydrogen.