A laboratory demonstration electromagnetic launcher

A large laboratory demonstration electro-magnetic launcher is currently under construction. The design objective is to launch a 0.3 kg projectile at muzzle velocities up to 3 km/s in a 4 m barrel using a peak accelerating current of 1.5 MA. The primary energy source is a 15 MJ pulsed homopolar generator. Compression of its output pulse is achieved using a 5 MJ toroidal storage coil and a 1.5 MA opening switch. The design of all components was completed in the period April to October 1979, and the detailed design and fabrication is at present underway. Completion is anticipated in mid-1981. This paper outlines the design effort and present fabrication status.     

A single dose of mifepristone induces ovulation in pseudopregnant rats

We used mifepristone (M) to evaluate the role of progesterone in maintaining pseudopregnancy. Cycling rats were made pseudopregnant (psp) by cervico-vaginal stimulation (CVS) on the day of estrus (day 0) and received 10 mg/kg M or vehicle (control groups) on day 3. Blood samples were taken at 06.00 h on days 4, 6 or 7 or at 18.00 h on days 3, 4, 6 or 10. M induced proestrus 2 days later (day 5), estrus on day 6, and a second prolonged diestrus afterwards. Prolactin and progesterone levels were similar in the control and M treated groups excepting on day 6, when both were reduced in the M-treated animals, and these rats were in estrus, suggesting a temporary impairment of luteal function. To demonstrate activated corpora lutea the endometrium was scratched on the fourth day of the first or second diestrus in additional control and M-treated groups. The deciduomal response was seen in the control and M groups after scratching the endometrium on day 4 of the first or second diestrus, respectively, but M blocked the deciduomal response in the first diestrus. Ovulation was confirmed by finding that 66.7% of the M-treated rats showed ova in the Fallopian tubes on the M-induced estrus and 4 out of 10 of the M rats placed with males on the M-induced proestrus showed spermatozoa in the vaginal smears. Half of these became pregnant, delivering 2 pups each. The results show that M can induce ovulation in psp rats, demonstrating that the anovulation observed after CVS is dependent on progesterone, yet luteal function persists after M in pseudopregnancy. Progesterone may act either by suppressing LH secretion or by permitting prolactin secretion, or both. Moreover, progesterone is required to maintain endometrial responsiveness.     

Emack electromagnetic launcher commissioning

The EMACK laboratory demonstration electromagnetic launcher was designed and fabricated by the Westinghouse R&D Center and installed at the R&D Center for commissioning in late 1981. Subsequently, in February, 1982, a series of five test shots was made to commission the system and determine its operating characteristics. This paper summarizes the essential engineering details of the system components and the results of the commissioning tests.     

Estradiol implants in the arcuate nucleus induce lactogenesis in virgin rats. Role of progesterone

Peroxisomal proliferators induce in rodents hepatic hyperplasia and hypertrophy; the significant increase in the peroxisomal population is accompanied by specific and reversible induction of some peroxisomal enzymes. In suckling rats born from clofibrate-treated mothers, a massive removal of proliferated organelles occurs within 3 days of recovery. In the present paper we examined the early stages of the recovery period in liver of male rats treated with clofibrate for 5 days. The lysosomal involvement in the removal of drug-induced peroxisomes was investigated under physiological conditions, i.e. in the absence of inhibitors of the autophagic process. Biochemical results indicate that peroxisomal beta-oxidation, but not catalase activity, returns to the control values within the examined period. Total acid phosphatase activity is not affected by clofibrate treatment, but following fractionation on a linear density gradient the lysosomal marker enzyme activity is shifted towards lower density values, particularly at day 1 and 2 of recovery. This class of organelles possibly represents lysosomes involved in active autophagic processes. Acid phosphatase cytochemistry shows an increase of lysosome number at day 1 of recovery. Combination of acid phosphatase cytochemistry either with catalase cytochemistry or with catalase immunogold labelling allows to reveal organelles containing both marker enzymes. These results strongly support the involvement of autophagic processes in the removal of proliferated peroxisomes.     

Regulation of prolactin secretion by adrenal steroids in oestrogen-treated ovariectomized rats: participation of endogenous opioid peptides

The purpose of the present study was to determine whether glucocorticoid inhibition of prolactin (PRL) release in oestrogen-treated ovariectomized (OVX) rats is mediated by endogenous opioid peptides (EOPs). All the animals were OVX and given oestradiol benzoate (OB, 20 microg/rat, s.c.) 2 weeks later (day 0). On day 3 they received vehicle, mifepristone (MIF, 10 mg/kg, s.c.) or hydrocortisone (HYD, 2 mg/rat, s.c.), in combination with the opioid antagonist naloxone (NAL, 2 mg/kg, i.p.) or vehicle. Serum PRL concentration was then measured by RIA at 13.00 and 18.00 hr, to include assessment of diurnal variation of PRL secretion. At 13.00 hr either MIF or NAL alone increased PRL secretion with no additional effect when NAL was combined with MIF. HYD had no significant inhibitory effect, but NAL with HYD increased PRL secretion. At 18.00 hr serum PRL concentration was higher than at 13.00 hr, and not affected significantly by MIF or NAL alone, although PRL secretion was increased by treatment with both. HYD inhibited PRL secretion and this inhibition was prevented by NAL. In a second experiment to distinguish antiglucocorticoid and antiprogesterone effects of MIF, we administered progesterone (2 mg/rat, s.c.) or a specific progesterone antiserum. In contrast with MIF, the progesterone antibody had no effect on PRL secretion at 13.00 hr, nor on the stimulation by NAL, while progesterone (unlike HYD) increased PRL secretion and NAL attenuated this response; this was opposite to the effect of NAL with HYD. Similarly, at 18.00 hr the interaction of MIF and NAL was not explained by antagonism of progesterone. Together, these results indicate inhibition of PRL by glucocorticoids but not progesterone, mediated in part by EOPs. At 18.00 hr endogenous glucocorticoids do not regulate oestrogen-stimulated PRL release, although HYD is inhibitory through EOPs.     

Experimental launcher facility - ELF-I: Design and operation

The ELF-I system has recently become fully operational and the experimental program begun. This system uses a 36 kJ, 5 kV capacitor bank as a primary pulse power source. When used in conjunction with a 5 μH pulse conditioning coil, a 100 kA peak current and ∼10 ms wide pulse is obtained. The launcher barrel is 2 m long with a 12.7 mm square bore. With the launched mass in the range of 3 to 7 g velocities in excess of 1 km/s have been obtained. An extensive array of diagnostic instruments have been installed on the system to obtain measurements of current, breech and muzzle voltage, in-bore velocity profiles, and terminal velocity. Problems associated with electromagnetic interference and high common-mode voltages have been addressed and solved. A three station, 150 kV, flash x-ray system is operational for obtaining in-bore photographs of the projectiles. Details of the mechanical and electrical design and the instrumentation system will be presented. The experimental program, now underway, is directed towards obtaining information on armature-rail interactions at sliding velocities up to 1 km/s for both metallic and plasma armatures. One particular problem being addressed is that of current transfer in the breech where the sliding velocity is very low. Experimental results and their analysis are presented.     

Inhibitory effect of prostaglandin F2 alpha on oxytocin release and on milk ejection in lactating rats

Eleven Southdown male lambs averaging 19.8 kg were randomly allotted to two groups and fed diets containing 7.7% (low-N) or 15.8% (high-N) crude protein. All of the supplemental nitrogen in the high-N diet was supplied as urea. Intake of the low-N and high-N diets averaged 372.3 g and 340.5 g/day, respectively. Findings at the end of the thirty-day trial were: (1) mean body weights unchanged for the two groups; (2) plasma urea nitrogen three-fold higher in the high-N (19.07 mg/100 ml) than the low-N (6.57) animals; (3) similar hepatic activity levels of three urea cycle enzymes (ornithine transcarbamylase, argininosuccinase, arginase) in the two groups, and (4) similar liver weights and liver protein concentration. The absence of adaptive change in enzyme levels suggests the hypothesis that addition of non-protein nitrogen to maintenance diets may cause ammonia intoxication by exceeding the liver's reserve capacity for urea synthesis.     

Hormonal profile and reproductive performance in lactation deficient (OFA hr/hr) and normal (Sprague-Dawley) female rats

Lactation deficiency may have important consequences on infant health, particularly in populations of low socioeconomic status. The OFA hr/hr (OFA) strain of rats, derived from Sprague-Dawley (SD) rats, has deficient lactation and is a good model of lactation failure. We examined the reproductive performance and hormonal profiles in OFA and SD strains to determine the cause(s) of the lactation failure of the OFA strain. We measured hormonal (PRL, GH, gonadotropins, oxytocin, and progesterone) levels by RIA in cycling, pregnant, and lactating rats and in response to suckling. Dopaminergic metabolism was assessed by determination of mediobasal hypothalamic dopamine and dihydroxyphenylacetic acid (DOPAC) concentrations by HPLC and tyrosine hydroxylase expression by immunocytochemistry and western blot. OFA rats have normal fertility but 50% of the litters die of malnutrition on early lactation; only 6% of the mothers show normal lactation. The OFA rats showed lower circulating PRL during lactation, increased hypothalamic dopamine and DOPAC, and impaired milk ejection with decreased PRL and oxytocin response to suckling. Before parturition, PRL release and lactogenesis were normal, but dopaminergic metabolism was altered, suggesting activation of the dopaminergic system in OFA but not in SD rats. The number of arcuate and periventricular neurons expressing tyrosine hydroxylase was higher in SD rats, but hypothalamic expression of TH was higher in OFA rats at the end of pregnancy and early lactation. These results suggest that the OFA rats have impaired PRL release linked with an augmented dopaminergic tone which could be partially responsible for the lactational failure.     

X-ray Computed Tomography for Evaluation of Density Gradient Formation during the Compaction of Spray-Dried Granules

X-ray computed tomography was used to quantify the internal structure of compacts made from poly(vinyl alcohol)-containing spray-dried agglomerates at specific levels of humidity. High humidities increased the average density but decreased the uniformity of the density distribution. Lower levels of humidity generally produced more diffuse high density zones. Internal uniformity is superior at lower humidities where agglomerate fracture is more common than gradual agglomerate deformation. SEM has been used to determine zone-specific agglomerate behavior at 0% and 98% relative humidity. These results can be used to connect gradient development to compaction curve behavior.