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Biomedical subjects

M Ring

Publications and source records attributed to M Ring.

54 records · Page 3Linked to original sources
PubMed1980

Cumulative alterations in rat behavior during continuous administration of LSD or mescaline: absence of tolerance?

Male hooded rats were observed for 6 days following implantation with slow-release subcutaneous pellets containing LSD, mescaline, or control vehicle solution. In animals housed in isolation cages, continuous hallucinogen administration resulted in a gradual increase in head twitches and catatonic postures which peaked 3--4 days after pellet implantation and then declined. In animals housed in social colonies, there were also delayed increases in behavior following hallucinogen-pellet implantation, but these principally involved social behaviors such as fighting by mescaline-treated animals and social grooming by LSD-treated animals. This finding of gradual and cumulative effects of continuous hallucinogen administration contrasts with the usual finding of a rapid tolerance to hallucinogens following repeated injections.

Animals↗
PubMed1979

Detection of environmental depigmenting substances.

We systematically screened the depigmenting capacity of several phenols, catechols and organic antioxidants. Clear-cut depigmentation was achieved with monomethyl ether of hydroquinone (MMH) and tertiary butyl catechol (TBC) using black guinea pigs and black mice as animal models. A goal was to establish a reliable in vivo method to demonstrate or to predict the depigmenting action of chemicals on mammalian melanocytes. There was no universal solvent or optimal body site, although all tested areas could be depigmented. Irritation induced by some vehicles and test materials produced false positive responses. False negative responses with known depigmenting chemicals were observed. Utilizing these observations, we propose a model for screening medicinal and industrial chemicals for depigmenting capacity.

Animals↗
PubMed1979

And up.

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Dentures↗
PubMed1976

Remember the Alamo!

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Laboratories, Dental↗
PubMedDate not supplied

The properties of beta-galactosidases (Escherichia coli) with halogenated tyrosines.

An Escherichia coli tyrosine auxotroph (MR1) with an inducible lacZ was generated by mutagenesis. Of several tyrosine derivatives tested, only m-fluorotyrosine supported the growth of this mutant and allowed synthesis of active beta-galactosidase. The pH profiles of the beta-galactosidase that was obtained when this mutant was grown on m-fluorotyrosine (81.5% of the tyrosine was replaced by m-fluorotyrosine) indicated that a tyrosine may be acting as a general acid-base catalyst and that it (or another tyrosine with the same pKa) may be involved in substrate binding. Inactivation of normal beta-galactosidase by treatment with lactoperoxidase in the presence of I- did not affect affinity-column binding, but incubation of this iodinated beta-galactosidase with chymotrypsin caused a rapid degradation of a portion of the treated enzyme equal to the portion of the activity that was lost. A study with 125I- showed that the rapid degradation was mainly confined to iodinated molecules of enzyme. These studies indicate that iodination of beta-galactosidase does not affect binding ability, but causes the enzyme to lose catalytic activity and become susceptible to chymotryptic action. Chloroperoxidase also caused rapid inactivation of normal beta-galactosidase in the presence of Br- or I-, but there was a lag followed by a slow inactivation in the presence of Cl-.

Binding Sites↗
PubMedDate not supplied

Engineering and physics in dental technology. Part 2.

Part 2 covers the areas of friction and lubricants, cross sections, parallelism, passivity and equilibration, levers, reducing the radius, immobilization, and transmitral of forces. Some elements of biomechanics are included in the article because of the interrelationship of biomechanics to engineering.

Dental Clasps↗