Characteristics of laser surface melted aluminum alloys

Specimens of Al-Fe 1-4 w/o, 2024 and 6061 Al have been surface melted with a pulsed Nd-glass laser. A TEM and SEM study showed that the dendrite spacings were from 2500 A to 4000 A which corresponds to a cooling rate of over 10(6) degrees C/sec. Melt depths obtained were in the range of 30-100 microm. No significant surface vaporization was observed at energy densities up to 440 J/cm(2). Fracture surfaces of the commerical alloys demonstrated elongated porosity in the melt areas, probably due to internal hydrogen.

Differential responsiveness of central noradrenergic and dopaminergic neuron tyrosine hydroxylase to hypophysectomy, ACTH and glucocorticoid administration

Hypophysectomy leads to a small increase in tyrosine hydroxylase activity of all brain areas containing noradrenergic neurons or tuberoinfundibular dopamine neurons, but nigroneostriatal dopamine neurons are not so affected. ACTH or corticosterone treatment inhibited this effect of hypophysectomy in some noradrenergic neurons and in tuberoinfundibular dopamine neurons. These data showing differential responsiveness of tyrosine hydroxylase in different brain areas are compatible with differences in regulation or molecular form of tyrosine hydroxylase in central noradrenergic and dopaminergic neurons. The disparity between increased hypothalamic tyrosine hydroxylase activity and decreased norepinephrine turnover following hypophysectomy may result from a change in the rate-limiting step to the hydroxylation of dopamine.

Effect of beta-endorphin on striatal dopamine metabolism

Acute intraventricular administration of human beta-endorphin increased 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) concentrations in rat striatum at a time when the catatonic effect was also present. This effect of beta-endorphin is compatible with increased striatal dopamine turnover and is similar to the effect noted previously with morphine administration.

Abnormalities in growth hormone and insulin release in short but otherwise normal patients. The arginine-insulin-glucose (AIGT) stimulation and suppression test

Arginine-insulin stimulation and IV glucose suppression (AIGT) tests were used to evaluate release of insulin and growth hormone. Adult patients responded normally. Hypopituitary patients showed no hGH response. One third of short normal patients showed abnormal hGH responses to glucose suppression. Two thirds of the short normal patients showed poor insulin responses to either amino acid or glucose stimulation. Such patients might have abnormalities in release mechanisms for insulin and suppression mechanisms for hGH and this might contribute to their growth failure.

Site-specific deoxyribonucleases in Bacillus subtilis and other Bacillus strains

We systematically studied site-specific deoxyribonucleases in Bacillus strains and detected deoxyribonuclease activities in 20 of 62 strains tested.

Influence of hippocampectomy on gastric ulcer in rats

Hippocampectomized male rats were prepared, and the incidence as well as severity of gastric ulceration upon restraint were compared with those of normal control animals and controls with localized damage to the cortex over the hippocampus. In another experiment, observations on gastric ulceration were made without restraint in hippocampectomized animals, normal controls, controls with cortical damage, vagotomized animals and animals that received hippocampectomy as well as vagotomy. Both in restrained and unrestrained states, the incidence of animals with ulcer as well as the number and the total area of ulcers per stomach were significantly larger in the hippocampal animals than they were in the other animal groups. Vagotomy abolished the effect of hippocampectomy upon gastric ulceration in the unrestrained state. We infer that the hippocampus helps to protect the stomach from ulceration partly by controlling vagal activity.

Influence of ginseng on mating behavior of male rats

Experiment on the mating behavior of male albino rats paired with receptive females established that in comparison with control animals, males under the influence of ginseng (a) began ejaculation earlier and repeated the action more often in a 45-minute observation period and (b) deposited more copulation plugs in 10 days. The data suggest that ginseng facilitates the mating behavior of male rats.

An easy and safe technique for nephrostomy

By an atraumatic technique of nephrostomy, dysfuncti-n of the nephrostomy due to hemorrhage during the early postoperative period can be prevented. The nephrostomy can be changed at any time without difficulty by the use of this technique.

Effect of hippocampectomy on sleep patterns in cats

The study was planned to see if the hippocampus has an influence on fast wave sleep (FWS) as well as on slow wave sleep (SWS). From 8 male cats EEG, EMG and EOG were recorded for 24 h, first under normal conditions, secondly after cortical damage to the dorsal marginal portion of posterior ectosylvian gyrus, and thirdly following hippocampectomy done through the cortical damage. From the records, SWS, FWS and the sleep state (defined as a sequence of SWS or SWS-FWS phases between two successive waking states) were measured in terms of their occurrence, the mean duration and the total time they occupied in the day, night and 24 h. In addition, sleep sequences were classified according to the number of constituent sleep phases. Cortical damage did not affect SWS, FWS, or sleep state with regard to their occurrence, the mean duration, and the total time they occupied in 24 h. Nor did it affect the proportion of short and long sequences. The circadian variation of sleep was clearly retained. Hippocampectomy significantly reduced the total time occupied by sleep state, SWS and FWS, increased the occurrence of sleep state and SWS phase against decreased incidence of FWS phase, and reduced the mean duration of sleep state and SWS phase. Hippocampectomy also significantly increased the occurrence of sleep sequences with only one SWS phase at the cost of sequences with alternating SWS and FWS phases. Following hippocampectomy, the circadian variation of sleep was not only retained, but actually exagerated. The hippocampus in inferred to facilitate the FWS as well as the SWS phase of sleep.