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Biomedical subjects

N Foster

Publications and source records attributed to N Foster.

7 recordsLinked to original sources
PubMed1992

Longitudinal sensitivity of the Fuld cholinergic profile to Alzheimer's disease.

The diagnostic sensitivity of a profile (Fuld, 1984) thought to mark cholinergic changes in Alzheimer's Disease (AD) was examined in a sample of 53 patients meeting criteria for AD on two occasions and in 19 patients for three occasions. The low obtained sensitivities of the Fuld profile (17%-26%) across testings is consistent with previous studies that used a single time point. The findings also revealed unstable positive and negative profiles over time. There were no performance differences on intellectual or memory measures when comparing subjects identified as positive or negative by the Fuld index. The results demonstrate that the index is insensitive to the dementing process and is a poor diagnostic marker for AD.

Aged↗
PubMed1991

Determination of the relative amounts of free and complexed manganese ions in aqueous solution by nuclear magnetic resonance.

The ratio of the transverse relaxation rate to the longitudinal relaxation rate of water protons (T1/T2) at 90 MHz can be used to determine the relative amounts of free Mn2+ ions (the hexaquo ion) and chelated manganese ions when both species are present in the same aqueous solution. This technique is demonstrated for simple aqueous solutions containing known concentrations of both the free Mn2+ ion and a manganese(III) porphyrin. The accuracy of the method is found to be +/- 7.3% for the solutions considered in this report. The determinations of the relative amounts of the free Mn2+ ion and the manganese(III) porphyrin by this T1/T2 method are shown to agree well with those determined by nuclear magnetic resonance dispersion profiles. The theoretical basis of this ratio method as well as the scope and limitations in its application to aqueous solutions containing both free Mn2+ ions and chelated manganese species other than manganese(III) porphyrins are also discussed. This work demonstrates a unique use of NMR as a means for the quantitative analysis of manganese in which the effects of the metal ion on the solvent, and not the metal itself, are observed.

Magnetic Resonance Spectroscopy↗
PubMed1991

Dilemmas surrounding the identification of essential rural hospitals.

Criteria are needed for use in designating some rural hospitals as essential so that they may receive state or federal assistance. Three types of criteria are considered in this analysis: hospital volume measures, hospital competitiveness measures, and community need measures. The criteria sets reflect different assumptions about the relationship between need and demand for health services. Analysis of available data reveals that neither hospital volume nor competitiveness is correlated with community need, meaning that different hospitals would be designated as essential under each system. Implications are discussed.

Bed Occupancy↗
PubMed1978

Epstein-Barr virus (EBV) antibody in patients treated by radical radiotherapy for head and neck cancer.

Antibody against Epstein Barr Viral capsid (EBV-VCA) was measured in 65 patients with primary head and neck cancer referred for radical radiotherapy. Sixty-three percent had locally advanced cancer and 37% had early disease. Forty-eight percent had detectable antibody in their sera. Thirty-three percent had elevated titers (above 1:20 dilution). Only 19% of cases with early cancer had increased titers. Almost 50% of those with locally advanced cancer or recurrence following treatment had titers above 1:20. A rise in titer within six months following radiotherapy was associated with a significant incidence of recurrence. There was no correlation between delayed hypersensitivity skin reaction to 2--4 dinitrochlorobenzene (DNCB) and titer values. EBV-VCA may be an additional parameter which can be used to determine host defenses in patients with malignancies.

Antibodies, Viral↗
PubMed1976

The effect of diphenylhydantoin on the microbial assay of serum folate.

1. Two modifications fo the usual method of assay for folic acid in solutions are reported which appear to improve this procedure. These are a reduction of incubation time and dilution with 95% ethanol. 2. Experimental results are reported which indicate that Dilantin (5,5-diphenylhydantoin) does not interfere with the microbiological assay for folic acid.

Biological Assay↗
PubMedDate not supplied

Analysis of spectral changes in isotopically substituted porphyrins adsorbed on melanin surfaces by solid-state carbon-13 nuclear magnetic resonance spectroscopy.

Two synthetic, water-soluble porphyrins, tetra-4N-methyl-pyridyl porphyrin (T4NMPyP) and tetra-N,N,N-trimethylanilinium porphyrin (TMAnP), and their indium(III) complexes have been isotopically substituted for evaluation by solid-state NMR of their adsorption to melanin. Methyl carbons on the pyridyl and anilinium nitrogens on the periphery of the porphyrin are one site of substitution; the four equivalent meso carbons in the porphyrin ring are the second. Chemical shifts and line widths of the carbon resonances in the bulk porphyrins change after they are adsorbed on synthetic and natural melanins. These changes may be related to the predominant binding interactions involved in the adsorption process and suggest that chemisorption, involving strong interactions comparable to chemical bonds, occurs between charged groups in both ligand and substrate. Inhomogeneous line broadening of the resonances implies that variations in binding exist, which is in keeping with the known heterogeneous nature of the melanin polymer and the different steric demands of the porphyrin ligands. These solid-phase experiments illustrate the promise of NMR for elucidating information about the binding of soluble molecules to insoluble and structurally irregular biopolymers. Furthermore, they represent the first spectroscopic probe of the binding of cationic molecules to the biopolymer melanin in the solid state. Coupled with results from molecular modelling, they indicate that cationic porphyrins bind to melanin at similar sites.

Binding Sites↗