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Biomedical subjects

E Wei

Publications and source records attributed to E Wei.

At least 37 records · Page 2Linked to original sources
PubMed1977

Airborne mutagens bioassayed in Salmonella typhimurium.

Particulate airborne pollutants, collected in Buffalo, New York, and Berkeley, California, were asayed for mutagenic activity in the Ames Salmonella typhimurium test system. Mutagens requiring liver enzymes for activation, as well as direct acting mutagens, were readily detected in the Buffalo sample. By contrast, only direct acting mutagens were detected in the Berkeley sample.

Air Pollutants↗
PubMed1976

Physical dependence of opiate-like peptides.

Methionine-enkephalin and beta-endorphin, endogenous peptides with activities similar to those of opiates, were infused for 70 hours into the periaqueductal gray-fourth ventricular space of the rat brain. When challenged with a naloxone, a specific opiate antagonist, these animals manifested a typical morphine-like withdrawal syndrome. These results show that such peptides can cause physical dependence.

Animals↗
PubMed1976

Potency of the N3im-methyl analog of TRH in the induction of shaking movements in the rat.

The relative potencies of TRH analogs in provoking a shaking response in rats were determined. Bilateral administration of 0.011-2.0 mug TRH analog into the periaqueductal-fourth ventricular spaces of the barbiturate-anesthetized rat showed that N3im-methyl TRH was approximately 10X more potent than TRH, whereas N1im-methyl TRH was approximately 10X less potent than TRH. These results indicate that the potencies of the TRH analogs in inducing shaking parallel their thyrotropin-releasing activities.

Animals↗
PubMed1976

beta-endorphin is a potent analgesic agent.

beta-Endorphin, an opiate-like peptide, has potent antinociceptive properties when it is administered directly into the brain and assayed in the the tail-flick, hot-plate, and writhing tests in mice and in the wet shake test in rats. On a molar basis, beta-endorphin is 18 to 33 times more potent than morphine and its actions are blocked by the specific opiate antagonist, naloxone hydrochloride. The activity of beta-endorphin in vivo is also compared to other peptides that show opiate-like activity in assays in vitro.

Analgesics, Opioid↗
PubMed1975

Regional sensitivity of the rat brain to the inhibitory effects of morphine on wet shake behavior.

The aim of this investigation was to determine the brain regions which were most sensitive to the inhibitory effects of morphine on the shaking response of pentobarbital-anesthetized rats to ice water. The median inhibitory dose (ID50) of morphine sulfate administered intraventricularly was found to be 0.35 mug/rat. When morphine was bilaterally injected into different regions of the brain, the ID50 values ranged from 0.04 to 17.9 mug/rat. The lowest ID50 values (0.04-0.20 mug) were found in the periaqueductal gray, the medial preoptic area and the locus ceruleus. The ID50 values ranged from 0.65 to 1.6 mug for areas around the nucleus accumbens, the fasciculus retroflexus, the medical thalamus and the septal area; from 5.6 to 7.3 mug for various hypothalamic nuclei; and from 11.0 to 17.9 mug for the basal ganglia, reticular formation substantia nigra and the reticular nucleus of the thalamus. The brain areas with the lowest ID50 values are known to have thermoregulatory functions. The similarity of the shaking response to shivering is discussed. It is concluded that the central inhibitory effects of morphine on shaking are subserved by discrete neuroanatomical substrates located in medial subcortical structures.

Anesthesia↗
PubMed1975

Central sites of naloxone-precipitated shaking in the anesthetized, morphine-dependent rat.

Naloxone hydrochloride, an opiate antagonist, administered via the intracranial or parenteral route precipitates shaking behavior in the morphine-dependent rat. We made localized bilateral injections of naloxone HCl, 1.5 mug/rat, into 60 subcortical sites of the pentobarbital-anesthetized, morphine-dependent rat and found that two circumscribed areas of the brain, the medial hypothalamus and the periaqueductal-4th ventricular spaces, were selectively sensitive to naloxone-precipitated shaking. In the nondependent rat, morphine injections into the anterior diencephalon inhibited the shaking response to ice water; injections of morphine into the medial diencephalon were less effective. However, naloxone antagonized the morphine-inhibited shaking more effectively when injections of naloxone were made in the medial diencephalon than when injections were made in the anterior diencephalon. These results suggest that the reciprocal relationship of morphine and morphine-naloxone effects on shaking behavior may be regulated by topographically different structures in the diencephalon.

Animals↗