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Biomedical subjects

M L Jones

Publications and source records attributed to M L Jones.

At least 163 records · Page 9Linked to original sources
PubMed1982

Canine retraction with the edgewise appliance-some problems and solutions.

The three basic methods of canine retraction discussed all have their inherent advantages and disadvantages and all can cause problems. The retraction systems which slide canines along a relatively rigid archwire, would appear to have the advantage of achieving better controlled apical and crown movement but at the obvious cost of greater friction and binding than the sectional arch. Of course the direct headgear system to some extent avoids the consequences to the anchorage, but there again the force to the canine is only intermittent and movement consequently is slower than if elastic traction were applied. If sliding mechanics are used either with a J hook headgear to canines or elastic intra-traction from the molars, it would seem advisable to use a heavy round wire in at least a medium width bracket. To help decrease binding when using elastic traction, power arms would certainly seem to have a place, with the added benefit of patients having an accessible hook to change elastics themselves. If sectional arches are used it is advisable to use a heavy rectangular wire to maintain as much control as possible. Due to the compromise between horizontal flexibility and vertical rigidity already discussed, it is very easy to over-activate a sectional arch with its inevitable consequence of excessively tipping the canine and/or losing molar anchorage.

Cuspid↗
PubMed1981

Isolation of Escherichia coli mutants with elevated levels of membrane enzymes. A trans-acting mutation controlling diglyceride kinase.

We have developed a rapid autoradiographic colony assay for detecting mutants with elevated levels of certain biosynthetic enzymes. Four Escherichia coli strains in which the specific activity of the membrane enzyme diglyceride kinase is increased 5-10-fold have been obtained with this approach. The mutant kinase has the same thermal denaturation profile and subcellular localization as the wild type. Five other membrane enzymes involved in phospholipid bilayer assembly are unaffected. In one of these strains (GK-1) the mutation (dgkR-1) responsible for the elevated kinase has been mapped at a new site near minute 92, while the previously identified structural gene (dgk) lies near minute 90. When the structural gene for the kinase (dgk) is cloned on a multi-copy vector-like ColE1, the kinase can be overproduced 5-10-fold on the basis of gene dosage (Lightner, V. A., Larson, T. J., Tailleur, P., Kantor, G. D., Raetz, C. R. H., Bell, R. M., and Modrich, P. (1980) J. Biol. Chem. 255, 9413-9420). Introduction of such hybrid plasmids into a mutant harboring dgkR-1 leads to a multiplicative (rather than additive) effect, resulting in specific activities of diglyceride kinase that are 35-75-fold higher than normal. These results show that dgkR-1 is a trans-acting mutation and suggest the existence of novel regulatory proteins (or metabolites) that direct the expression of certain membrane enzymes.

Cell Membrane↗
PubMed1981

Physical restraint as positive reinforcement.

The reinforcing function of physical restraint was analyzed for three retarded individuals who had a history of restraint and appeared to enjoy it. Using a preference paradigm with one participant and a reversal design with two others, we found that an arbitrary response systematically increased for each participant when followed by brief periods of restraint. No comparable increases occurred in conditions in which responses were not reinforced or were followed by stimuli designed to control for the nonrestraint components of the restraint consequence. Results were discussed in terms of three clinical issues: determining the possible role of restraint in maintaining behavior problems such as self-injury in natural settings, preventing or eliminating the reinforcing function of restraint, and using restraint reinforcement in treating behavior problems when this consequence is the only identifiable reinforcer for an individual.

Adolescent↗
PubMed1980

A GLC and GC/MS study of the reaction between benzylpenicillin and BF3-methanol.

A study of the reaction of BF3-methanol with benzylpenicillin showed that penicillin could be converted to a form suitable for gas-liquid chromatography. This study indicated possible use of the reaction in an analytical method for penicillin, by determining the methyl phenylacetate product. A reaction rate and yield study was conducted using gas-liquid chromatography employing an internal standard for improved measurement accuracy. The reaction gave a relatively constant yield of 70 +/- 2% and was complete in less than 1 minute. Investigations of the identity of side products were conducted using GC/MS, UV, and IR. A variety of products, including penicillenates, penillates, penilloates, and acrylic acid esters, were indicated at very mild reaction conditions.

Boranes↗
PubMed1979

The acquisition of question formation in spoken English and American sign language by two hearing children of deaf parents.

This longitudinal study investigated the acquisition of question formation in spoken English and American Sign Language (ASL) by two young hearing children of deaf parents. The linguistic environment of the children included varying amounts of exposure and interaction with normal speech and with the nonstandard speech of their deaf parents. This atypical speech environment did not impede the children's acquisition of English question forms. The two children also acquired question forms in ASL that are similar to those produced by deaf children of deaf parents. The two languages, ASL and English, developed in parallel fashion in the two children, and the two systems did not interfere with each other. This dual language development is illustrated by utterances in which the children communicated a sentence in spoken English and ASL simultaneously, with normal English structure in the spoken version and sign language structure in the ASL version.

Child, Preschool↗
PubMed1979

Preparing the school-age child for adoption.

The development of an adoptive relationship for children who have been in the limbo of foster care is a continuous process. It is unrealistic to expect these families to live happily ever after. Agencies must begin developing regular services to meet the special needs of the families being created. To a large extent the issues that will have to be worked through relate to the stages of preparation outlined in this paper. Each stage in the child's growth may activate unresolved issues around the grief at the biological parents' rejection, confusion about identity or difficulty in working through problems. Future adoptive home recruitment must take this into account by providing training and other supports to families considering adopting the older child.

Adoption↗
PubMed1978

The use of physical restraint in the treatment of self-injury and as positive reinforcement.

Two experiments investigated the effects of a treatment package on the self-injurious behavior of three profoundly retarded persons who appeared to enjoy the physical restraints used to prevent their self-injury. The treatment package included physically restraining subjects contingent on increasing periods of time during which no self-injury occurred, and providing them with toys and attention during intervals between restraints. A reversal and multiple-baseline analysis documented that the rapid and complete reduction in self-injury by all subjects was due to this treatment package. Because these results suggested that physical restraint might function as a positive reinforcer, in a third experiment physical restraint was applied contingent on a marble placement response with one subject. A reversal design demonstrated that toy play systematically increased when each response resulted in restraint. The experiments have implications for the nonaversive remediation of self-injury in individuals who are restrained, as well as for the development and maintenance of self-injury in natural settings.

Adolescent↗
PubMed1970

Why locked doors?

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Hospital Administration↗