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Biomedical subjects

T E Johnson

Publications and source records attributed to T E Johnson.

142 records · Page 8Linked to original sources
PubMed1983

Snake antivenin administration in a patient allergic to horse serum.

We have described a case in which a potent epinephrine drip was useful in the management of a patient who needed antivenin and was allergic to horse serum. With 50 ml of 1:10,000 epinephrine in 500 ml of 5% dextrose in water, repeated anaphylactoid reactions were controlled. We believe that such a solution would be helpful in other patients having severe anaphylactic reactions to antivenin.

Adult↗
PubMed1982

Genetic analysis of life-span in Caenorhabditis elegans.

Crosses between Bristol and Bergerac strains of the self-fertilizing hermaphroditic nematode Caenorhabditis elegans do not show the heterosis effects for life-span that complicate analysis of interstrain crosses with Drosophila or mice. Instead they yield F1 progeny with life-spans similar to those of the parent strains. By analysis of life-span variation among progeny F2 populations from such crosses and by two independent analyses of life-spans among recombinant inbred lines derived from F2 individuals by 18 rounds of self-fertilization, we estimate that the heritability of life-span in C. elegans is between 20% and 50%. Recombinant inbred lines show a range in mean life-spans of 10 days to 31 days compared to life-spans of about 18 days for each of the two parental strains. We conclude that life-span variation in C. elegans has a substantial genetic component and that this organism offers promising opportunities for selective breeding of longer-lived strains and genetic analysis of senescence.

Aging↗
PubMed1980

Quantitation of the anticonvulsant cinromide (3-bromo-N-ethylcinnamamide) and its major plasma metabolites by thin-layer chromatography.

A quantitative thin-layer chromatography (TLC) procedure is described for the analysis of cinromide (3-bromo-N-ethylcinnamamide) and its two major metabolites, 3-bromocinnamamide and 3-bromocinnamic acid in plasma of the dog. These compounds were recovered from acidified plasma by extraction into benzene with a recovery of 95 +/- 5%. All three compounds were quantitated directly on a TLC plate by ultraviolet absorbance densitometry at 270 nm. The linear dynamic range for the quantitation of the compounds on a TLC plate ranged between 10 and 1000 ng. The complete procedure is useful in the working range of 50 ng/ml to 100 microgram/ml of plasma with a coefficient of variability of about 10%. Specificity of the method for parent drug and each of its plasma metabolites was confirmed by high-performance liquid chromatography. The method was used to determine the pharmacokinetics of cinromide and its two major plasma metabolites in dogs following a single oral dose of the drug.

Animals↗
PubMedDate not supplied

The spe-10 mutant has longer life and increased stress resistance.

We investigated the life span of spe-10 mutant nematodes. We also tested resistance of spe-10 mutants to ultraviolet (UV) light, heat, and paraquat and examined the relationship between resistance to UV light and the fertility defect of these animals. The spe-10 mutation significantly increased mean life span. Additionally, the mutation significantly increased resistance to both UV light and to heat. Resistance to paraquat was not significantly different from that of wild-type, nor were any dauers formed at 27 degrees C. No significant correlation was found between the UV resistance and the fertility defect, nor was the UV resistance attributable to a hormetic effect. These results reinforce the importance of stress resistance in specifying increased life span and indirectly suggest that this fertility defect is not a direct cause of life span extension.

Animals↗
PubMedDate not supplied

Genetic influences on aging.

Genetics is an important tool for identifying key molecular events that are involved in specifying biological functions. Genetic approaches have been used repeatedly to understand diverse biological phenomena: oncogenesis, development, and the cell cycle, but have only recently been applied to the analysis of organismic aging and senescence. The power of the genetic approach stems from two facts. First, genetic analyses allow the integration of phenomena that are analyzed at many levels of observation from the molecule to the intact organism, and second, genetics has the real power to reveal causality by factors that are not dependent upon the prejudice of the investigator. I discuss several areas where genetics has been fruitfully applied to the study of the aging processes: human genes identified by "segmental progeroid" mutations, neurological diseases of the elderly, the limited proliferative life span of human somatic cells in tissue culture, studies on the life span of the mouse, and genetic analysis of life span in shorter lived metazoans (Drosophila melanogaster and Caenorhabditis elegans), and the yeast Saccharomyces cerevisiae.

Aging↗
PubMedDate not supplied

Structural requirements and cell-type specificity for ligand activation of peroxisome proliferator-activated receptors.

The mammalian peroxisome proliferator-activated receptor (PPAR) family consists of three different subtypes, PPARalpha, hNUC1/PPARdelta and PPARgamma. Selective agonists have been identified for PPARalpha and PPARgamma but not for hNUC1, and consequently little is known about the genes that are controlled by this receptor. Using ligand-dependent transcription assays in COS-7 cells, we screened a variety of PPAR activating agents to identify a selective activator of hNUC1. We found that the potent peroxisome proliferator, Wy-14643, and the PPARgamma-selective thiazolidinedione, BRL 49653, were poor activators of hNUC1 (EC50s of > 100 microM). Short chain fatty acids (FAs) appeared more selective for PPARalpha than for hNUC1, whereas the very long chain FA, erucic acid (C22:1) was more selective for hNUC1. Using erucic acid as a probe, we conducted a topological similarity search of the Merck Chemical Collection and identified a fatty acid-like compound, L-631,033 4-(2-acetyl-6-hydroxyundecyl) cinnamic acid, that was a selective activator of hNUC1 (EC50 of 2 microM), but was much less selective for PPARalpha or PPARgamma (EC50s of > 100 microM). Structure-function analysis of PPAR activation by L-631,033 structural analogues showed that receptor selectivity depends on the position of the carboxyl group relative to the phenyl ring on the molecule. Transfection experiments in several cell types: an osteoblastic cell line (MB 1.8), a mouse liver cell line (ML-457), rat aortic smooth muscle cells (RSMCs) and COS-7 cells revealed differences in the activation profile of specific ligands. The most notable differences were observed in RSMCs, where transactivation by L-631,033 and Wy-14643, but not by BRL 49653, was markedly reduced, and in MB 1.8 cells, where oleic acid failed to activate PPARs. These findings identify certain structural features in PPAR-activating agents that modulate PPAR activation, and suggest that as with other nuclear receptors, activation is cell-type specific.

Animals↗
PubMedDate not supplied

Factors contributing to dentists' extraction decisions in older adults.

To evaluate which dental and non-dental factors contributed to dentists' extraction decisions in a sample of older adults, an archival study was conducted using community-dwelling and long-term-care older adults receiving dental care at an urban seniors' clinic. Four dentists who provided dental care to older adults reviewed patient records for whom they had extracted at least one tooth over a 21-month period. They identified one or more factors contributing to their extraction decisions. From 105 adults (mean age, 80.6), there were 221 extractions. Frequent contributors to dentists' extraction decisions included non-restorability in 53.8% of all extractions, dental caries (45.6%), prosthetic considerations (45.2%), and periodontal disease (40.3%). The non-dental contributors in 13% to 17% of extractions included patient/family request, inability to care for one's teeth, and financial limitations. When identifying the "most important" (or "primary") factor in their extraction decisions, dentists most frequently indicated non-restorability, followed distantly by patient/family request, periodontal disease, and financial limitations. This investigation demonstrates that non-dental factors are important in dentists' extraction decisions. Of these, patient/family request and financial limitations appear to be most influential.

Aged↗
PubMedDate not supplied

Preferences for an influences on oral health prevention: perceptions of directors of nursing.

Directors of Nursing (DONs) from 196 of 206 Nebraska long-term-care (LTC) facilities were sent a pre-tested questionnaire. The aim was to assess available on-site dental services, existing oral health education and prevention programs as well as future needs/preferences, and the influence of 10 factors in assessing and maintaining residents' oral health. Of the 196 DONs contacted, 126 (64%) participated. Only 36% of DON responders reported having on-site dental services. DONs indicated a preference for nursing staff (NS) oral health inservice training over other educational and/or programmatic proposals. When asked to select the five most influential factors in assessing and maintaining residents' oral health in their respective facilities, DONs selected resident factors (mean, 2.8) more often than NS factors (mean, 2.2). DONs most often identified residents' (R') ability to perform oral hygiene (n = 99), R' cooperation with OH assistance (n = 98), R' interest in their oral health (n = 83), NS interest in R' dental health (n = 70), and NS time constraints (n = 69).

Aged↗
PubMedDate not supplied

Elder abuse and neglect: detection, reporting, and intervention.

Dental providers are in an excellent position to identify elder abuse and neglect (EAN), yet they are often reluctant to report or intervene in cases of suspected elder maltreatment. This problem is widespread, and the negative impact of this dilemma cannot be ignored. In 1999, the American Dental Association's House of Delegates, through Resolution 44H-1999, urged constituent dental societies to educate their members about abuse and neglect and individual states' legal reporting requirements. The American Society for Geriatric Dentistry (ASGD), responding to a need to inform its members about this issue, requested this literature review on elder abuse and neglect. This paper emphasizes the role of the dental profession in ameliorating EAN and offers ASGD members recommendations to aid individual practitioners and staff in educating and assisting the profession in recognizing and reporting EAN.

Aged↗
PubMedDate not supplied

Ectopic (extradural) meningioma of the orbit: a report of two cases in children.

Meningiomas arising from the optic nerve or secondarily invading the orbit from the intracranial cavity are uncommonly encountered in children. Ectopic (extradural) meningiomas are exceedingly rare orbital tumors that do not originate from either the optic nerve or the intracranial meninges. We evaluated and treated two boys aged 7 and 10 years with probable primary ectopic (extradural) orbital meningiomas. Both patients presented with a gradual onset of progressive, painless proptosis. In addition, computed tomographic scans demonstrated involvement of the superomedial orbit without bony erosion or hyperostosis, but with expansion of the adjacent sinus. Neither tumor demonstrated attachment to the optic nerve or intracranial extension at the time of surgery. Both patients were successfully treated with complete surgical excision. Evaluation did not reveal the presence of neurofibromatosis in either child.

Child↗