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Biomedical subjects

M M Mahon

Publications and source records attributed to M M Mahon.

At least 19 recordsLinked to original sources
PubMed2000

Discontinuing treatment in children with chronic, critical illnesses.

Decisions about optimal treatment for critically ill children are qualitatively different from those related to adults. Technological advances over the past several decades have resulted in myriad treatment options that leave many children chronically, critically ill. These children are often technology dependent. With new technologies and new patient populations comes the responsibility to understand how, when, and why these technologies are applied and when technology should not be used or should be withdrawn. Much has been written about ethical decision making in the care of chronically, critically ill adults and newborns. In this article, relevant factors about the care of children older than neonates are described: standards, decision makers, age of the child, and pain management. A case study is used as a mechanism to explore these issues. Dimensions of futility, discontinuing aggressive treatment, and a consideration of benefits and burdens are integrated throughout the discussion to inform nurse practitioner practice.

Child, Preschool↗
PubMed1999

The aspartate aminotransferase-catalysed exchange of the alpha-protons of aspartate and glutamate: the effects of the R386A and R292V mutations on this exchange reaction.

1H-NMR was used to follow the aspartate aminotransferase-catalysed exchange of the alpha-protons of aspartate and glutamate. The effect of the concentrations of both the amino acids and the cognate keto acids on exchange rates was determined for wild-type and the R386A and R292V mutant forms of aspartate aminotransferase. The wild-type enzyme is found to be highly stereospecific for the exchange of the alpha-protons of L-aspartate and L-glutamate. The R386A mutation which removes the interaction of Arg-386 with the alpha-carboxylate group of aspartate causes an approximately 10,000-fold decrease in the first order exchange rate of the alpha-proton of L-aspartate. The R292V mutation which removes the interaction of Arg-292 with the beta-carboxylate group of L-aspartate and the gamma-carboxylate group of L-glutamate causes even larger decreases of 25,000- and 100,000-fold in the first order exchange rate of the alpha-proton of L-aspartate and L-glutamate respectively. Apparently both Arg-386 and Arg-292 must be present for optimal catalysis of the exchange of the alpha-protons of L-aspartate and L-glutamate, perhaps because the interaction of both these residues with the substrate is essential for inducing the closed conformation of the active site.

Aspartate Aminotransferases↗
PubMed1999

13C NMR study of how the oxyanion pKa values of subtilisin and chymotrypsin tetrahedral adducts are affected by different amino acid residues binding in enzyme subsites S1-S4.

A range of substrate-derived chloromethane inhibitors have been synthesized which have one to four amino acid residues. These have been used to inhibit both subtilisin and chymotrypsin. Using 13C NMR, we have shown that all except one of these inhibitors forms a tetrahedral adduct with chymotrypsin, subtilisin, and trypsin. From the pH-dependent changes in the chemical shift of the hemiketal carbon of the tetrahedral adduct, we are able to determine the oxyanion pKa in the different inhibitor derivatives. Our results suggest that in both the subtilisin and chymotrypsin chloromethane derivatives the oxyanion pKa is largely determined by the type of amino acid residue occupying the S1, subsite while binding in the S2-S4 subsites only has minor effects on oxyanion pKa values. Using free energy relationships, we determine that the different R groups of the amino acid residues binding in the S1 subsite only have minor effects on the oxyanion pKa values. We propose that the lower polarity of the chymotrypsin active site relative to that of the subtilisin active site explains why the oxyanion pKa is higher and more sensitive to the type of chloromethane inhibitor used in the chymotrypsin derivatives than in the subtilisin derivatives.

Alkylation↗
PubMed1999

Conceptual and technical considerations when combining large data sets.

Secondary analysis provides a useful method for the development of new knowledge. Larger samples can be constructed, and secondary analysis can be enhanced when data sets are combined. A standardized method for combining large data sets is crucial, yet literature on methods for combining large data sets for secondary analysis is lacking. The purpose of this article is to outline and explain the process of combining two or more large data sets (n = 276, n = 125) for secondary analysis by using these authors' previous work with large oncology and AIDS caregiver data sets.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Conceptual and pragmatic considerations in conducting a secondary analysis. An example from research of families.

In this article, the authors discuss conceptual and pragmatic considerations for conducting research of families using large secondary data sets. Conceptual considerations include establishing consistency among the theory, variables, and available data, and determining reliability and validity of the data in the context of the theory. Pragmatic considerations include the use of resources such as management of the data among several authors, criteria and methods for selection of a subsample, and, recoding of the data to examine dyadic difference scores. The Family Special Interest Group of the Eastern Nursing Research Society initiated this research as part of a project to analyze families using large national data sets. The purpose of the secondary analysis was to identify family beliefs about healt-promoting behaviors. Combining parent and teen data to create relational level data resulted in new information that had not been identified in the original survey.

Data Interpretation, Statistical↗
PubMed1999

Parent-teen worry about the teen contracting AIDS.

A secondary data analysis of the National Commission on Children: 1990 Survey of Parents and Children was conducted with a subsample of 457 parent-teen pairs who responded to the "worry about AIDS" question. The teen's worry about contracting AIDS was associated with race, parent's education, the amount of discipline from the parent for engaging in sex, the teen's desire to talk to the parent about the problem of sex, the teen's rating of the neighborhood as a safe place to grow up, whether the parent listened to the teen's telephone interview, and the parent's response to whether his or her teen had a history of sexually transmitted disease. Of the parent-teen pairs in the subsample, 46% (N = 210) agreed in their responses about worry. Agreement was more frequent among the parent-teen pairs when compared to randomly constructed surrogate pairs. Dyadic analysis supported a family system view of perceived susceptibility.

Acquired Immunodeficiency Syndrome↗
PubMed1998

The pyridoxal-5'-phosphate-dependent catalytic antibody 15A9: its efficiency and stereospecificity in catalysing the exchange of the alpha-protons of glycine.

13C-NMR has been used to follow the exchange of the alpha-protons of [2-(13)C]glycine in the presence of pyridoxal-5'-phosphate and the catalytic antibody 15A9. In the presence of antibody 15A9 the 1st order exchange rates for the rapidly exchanged proton of [2-(13)C]glycine were only 25 and 150 times slower than those observed with tryptophan synthase (EC 4.2.1.20) and serine hydroxymethyltransferase (EC 2.1.2.1). The catalytic antibody increases the 1st order exchange rates of the alpha-protons of [2-(13)C]glycine by at least three orders of magnitude. We propose that this increase is largely due to an entropic mechanism which results from binding the glycine-pyridoxal-5'-phosphate Schiff base. The 1st and 2nd order exchange rates of the pro-2S proton have been determined but we were only able to determine the 2nd order exchange rate for the pro-2R proton of glycine. In the presence of 50 mM glycine the antibody preferentially catalyses the exchange of the pro-2S proton of glycine. The stereospecificity of the 2nd order exchange reaction was quantified and we discuss mechanisms which could account for the observed stereospecificity.

Antibodies, Catalytic↗
PubMed1998

A restraint on restraints: the need to reconsider the use of restrictive interventions.

Children with behavior problems are put in units with milieu therapy for the support and guidance of a specialized health care team, supposedly experts in the care of children with these unique and urgent needs. The reality of such units, however, is that those with the most contact with the children are often inadequately prepared, both in terms of knowledge and skills, to manage disruptive behaviors. As a result, the milieu that is supposed to provide support and structure can actually exacerbate the trauma for the vulnerable child. Preliminary data are presented from an ongoing study that is investigating the experiences and memories of formerly hospitalized children. Three types of traumatic experiences are described: vicarious trauma, alienation from staff, and direct trauma. Many of the traumatic events endured by child patients are the result of an inappropriate use by staff of power and force. There was a marked lack of understanding by the children of why given interventions were used. Although coercive interventions are sometimes necessary, ethical, legal, and other professional considerations make it clear that more work is needed. Research to identify the patterns of lack of knowledge and skills, as well as to develop appropriate interventions are recommended.

Adolescent↗
PubMed1996

Dirty hands: the underside of marketplace health care.

The ethos of the corporation and the urgency for profit maximization place pressures on health care corporations to act in a way that may be incompatible with ethical practice. Profit-driven incentives often result in corporate deviance and criminal behavior. Nurses may be pressured to go along with schemes that may be unethical or illegal and because of shaky job markets may be unable to adhere to professional ethical guidelines. Recent events in health care are drawn on to argue that ethical theory and research must begin to consider the issue of moral compromise of professionals as a result of deviant organizational environments.

Decision Making↗
PubMed1995

Childhood bereavement after the death of a sibling.

The article describes a study designed to explore the processes of sibling bereavement and to compare children's impressions with those of their parents. The Institute of Medicine model was used as a sensitizing framework for the study. Constant comparative technique was used to analyze data from a pilot study of 18 bereaved siblings aged 4 to 23 years. Sadness was the most common reaction after sibling death. Mothers were most often cited as being helpful; friends and fathers were also helpful. People who were not actively supportive were not helpful. Many children described feeling protective of their parents, and several children described personal growth.

Adolescent↗
PubMed1994

Liver disease in the elderly.

While there are no liver diseases specific to advanced age, the presentation, clinical course and management of liver diseases in the elderly may differ in important respects from younger individuals. The management of older patients with specific liver diseases should be informed by these differences. Alcoholic liver disease presents at a more advanced stage, drug induced liver disease and viral hepatitis may also be more severe. It is increasingly recognised that primary hepatocellular cancer arises in elderly cirrhotics regardless of the etiology of the cirrhosis, the risk highest in hemochromatosis and cirrhosis arising from hepatitis B and C.

Aged↗
PubMed1993

Children's concept of death and sibling death from trauma.

Factors influencing children's concept of death (their understanding of finality, inevitability, and universality) were examined. A bereaved group of 29 siblings (5 to 12 years of age) of children who died from trauma were interviewed 13 to 17 months after their sibling's death. A comparison group (n = 29) of nonbereaved siblings who had not experienced a sibling's death was matched for age, race, gender, and sociodemographic background. Demographic data, a Piagetian developmental assessment, and a concept of death assessment incorporating vignettes were used to collect data. The experience of sibling death from trauma did not significantly influence acquisition of an accurate concept of death; developmental level (p = 0.0001) and age (p = 0.0003) were significant predictors. Of the 5-year-old subjects in this study, 45.7% had an accurate concept of death, as did > 60% of 6-, 7-, and 8-year-old subjects, 100% of 9-, 11-, and 12-year-old subjects, and 90% of 10-year-old subjects. This reflects an understanding of death at a much younger age than reported by previous researchers.

Age Factors↗