Search PubMed⌕ Search

Biomedical subjects

R H Felton

Publications and source records attributed to R H Felton.

25 records · Page 2Linked to original sources
PubMed1971

Compounds I of catalase and horse radish peroxidase: pi-cation radicals.

Two-electron oxidation of cobaltous octaethylporphyrin [Co(II)(Et)(8)P] yields a stable pi-cation radical [Co(III)(Et)(8)P](2+.), the optical spectrum of which exhibits spectral changes dependent upon the nature of the counterion. Comparison of these spectra with those of Compounds I of horseradish peroxidase and catalase leads us to propose that these Compounds I contain a pi-cation radical of the heme prosthetic group. This proposal explains the oxidation level, optical spectra, and stability of the primary compounds without recourse to properties such as stoichiometric mixtures of special porphyrins, stable Fe(V) porphyrins, or unique conformers of heme porphyrins. Explanations are advanced to account for the missing electron spin resonance signal of Compound I of horseradish peroxidase.

Catalase↗
PubMed1970

The pi-Cation Radical of Chlorophyll a.

Chlorophyll a undergoes reversible one-electron oxidation in dichloromethane and butyronitrile. Removal of the electron by controlled potential electrolysis or by stoichiometric charge transfer to a known cation radical yields a radical (epr line width = 9 gauss, g = 2.0025 +/- 0.0001) whose optical spectrum is bleached relative to that of chlorophyll. Upon electrophoresis this bleached species behaves as a cation. By comparison with the known properties of pi-cation radicals of porphyrins and chlorins, the chlorophyll radical is also identified as a pi-cation. Further correlation of optical and epr properties with published studies on photosynthesis leads to the conclusion that oxidized P700, the first photochemical product of photosystem I in green plants, contains a pi-cation radical of the chlorin component of chlorophyll a. This radical is the likely source of the rapidly-decaying, narrow epr signal of photosynthesis.

Journal Article↗
PubMedDate not supplied

Selective predictive value of rapid automatized naming in poor readers.

This study considers the differential predictive value of rapid naming tests for various aspects of later reading, where the differential is between nondisabled and poor readers. Two large-N longitudinal samples of students who have been evaluated from third through eighth grades are studied: (a) a randomly accessed, normally distributed group including students with varying degrees of reading ability (N = 154), and (b) a group of poor readers whose single-word reading in third grade is at or below the population 10th percentile (N = 64). Outcomes in fifth and eighth grade were measured in both groups. Single-word reading in both grades was strongly predicted from third-grade rapid naming only within the poor readers, even when IQ, socioeconomic status, and third-grade single-word reading were statistically controlled. Although rapid naming had predictive value within the large, normally distributed group, its predictive power was entirely absent in the average-reading nondisabled students who were between the 10th and 90th percentiles (n = 122). The fact that rapid naming has predictive power only for poor readers but not for average readers is interpreted as suggesting that impaired readers are qualitatively different from the normal-reading population and are not simply the "tail" of a normal distribution of reading ability. It also seems that it is the automaticity of retrieval, not the knowledge of names itself (as in confrontational naming tasks), that gives the predictive power in rapid naming. These data are considered in light of the one- and two-factor theories of the underlying processes involved in reading disability or dyslexia.

Anomia↗