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Biomedical subjects

A Abbott

Publications and source records attributed to A Abbott.

At least 199 records · Page 11Linked to original sources
PubMed1996

The carbohydrate moieties of the beta-subunit of Na+, K(+)-ATPase: their lateral motions and proximity to the cardiac glycoside site.

The beta-subunit associated with the catalytic (alpha) subunit of the mammalian Na+, K(+) -ATPase is a transmembrane glycoprotein with three extracellularly located N-glycosylation sites. Although beta appears to be essential for a functional enzyme, the role of beta and its sugars remains unknown. In these studies, steady-state and dynamic fluorescence measurements of the fluorophore lucifer yellow (LY) covalently linked to the carbohydrate chains of beta have demonstrated that the bound probes are highly solvent exposed but restricted in their diffusional motions. Furthermore, the probes' environments on beta were not altered by Na+ or K+ or ouabain-induced enzyme conformational changes, but both divalent cation and oligomycin addition evoked modest changes in LY fluorescence. Frequency domain measurements reflecting the Förster fluorescence energy transfer (FET) occurring between anthroylouabain (AO) bound to the cardiac glycoside receptor site on alpha and the carbohydrate-linked LY demonstrated their close proximity (18 A). Additional FET determinations made between LY as donor and erythrosin-5-isothiocyanate, covalently bound at the enzyme's putative ATP binding site domain, indicated that a distance of about 85 A separates these two regions and that this distance is reduced upon divalent cation binding and increased upon the Na+E1-->K+E2 conformational transition. These data suggest a model for the localization of the terminal moieties of the oligosaccharides that places them, on average, about 18 A from the AO binding site and this distance or less from the extracellular membrane surface.

Adenosine Triphosphate↗
PubMed1996

Transcutaneous electrical nerve stimulation (TENS) treatment outcome in long-term users.

OBJECTIVE: Previous reviewers of the literature on transcutaneous electrical nerve stimulation (TENS) outcome have concluded the following: (a) there are few long-term TENS follow-up studies, and (b) fewer studies have addressed the effect of long-term TENS use on outcome variables other than pain (e.g., function). DESIGN/SETTING/PARTICIPANTS/OUTCOME MEASURES: From a population of 2,003 chronic pain patients (CPPs) who bought a TENS device for pain management, 506 patients were randomly selected and interviewed by telephone long enough after purchase to allow at least 6 months of TENS use. The interview process used a structured "skip" questionnaire designed to assess the CPPs' perceptions regarding the effectiveness of TENS for a variety of outcome variables. Of the 506 CPPs interviewed, 376 (74.3%) had used their TENS device for 6 months or longer and were defined as long-term users. The responses of this group of CPPs to the telephone questionnaire were then subjected to statistical analysis. RESULTS: Paired t-tests, correlated z-tests, SS Wilks, and chi-square tests demonstrated statistically significant change or improvement (p < 0.05) that paralleled the introduction of TENS use in the following outcome variables: less pain interference with work, home, and social activities; increased activity level and pain management; decreased use of other therapies (e.g., physical therapy, occupational therapy, chiropractic); decreased use of narcotics, tranquilizers, muscle relaxants, nonsteroidal anti-inflammatory drugs and steroids. CONCLUSIONS: The results suggest that TENS is associated with improvement on multiple outcome variables in addition to pain relief for CPPs who are long-term users. Also, for some CPPs, long-term TENS use continues to be effective.

Chronic Disease↗