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Biomedical subjects

J Fox

Publications and source records attributed to J Fox.

At least 271 records · Page 15Linked to original sources
PubMed1979

Effects of on-line symptom-processing on history-taking and diagnosis--a simulation study.

Techniques for computer-assisted diagnosis have been largely confined to off-line use, and there has been little examination of their potential role directly in the clinical setting. It is argued that the potential benefits of on-line diagnostic aids are considerable. A major barrier to such developments is uncertainty that the practical use of an on-line system would lead to the improvements in diagnostic effectiveness that more conventional off-line systems have already demonstrated. A series of studies in which clinicians took the histories of computer-simulated 'patients' presenting with dyspepsia, and formed diagnoses on the basis of these histories with and without computer assistance, suggested that diagnostic effectiveness may be greatly improved with on-line computer assistance. Some reasons for this improvement are discussed and it is concluded that the clinician and the on-line computer bring different but complementary types of knowledge to the diagnostic task. Though many practical questions remain to be answered the findings establish the principle of on-line symptom processing.

Diagnosis, Computer-Assisted↗
PubMed1979

Differential effects of age and cerebral atrophy upon span of immediate recall and paired-associate learning in older patients suspected of dementia.

Seventy-eight patients suspected of dementia, 50 years of age or older and without evidence of focal cerebral lesion or systemic illness, were administered the Digit-Span Forward and Paired-Associate Learning subtests of the Wechsler Memory Scale. Computerized axial tomography, allowing a visualization and measurement of the lateral ventricles and cortical sulci, was employed to measure cerebral atrophy. Four groups were defined as follows: (1) age 50-69, without atrophy (N = 27), (2) age 50-69, with atrophy (N = 17), (3) age 70-89, without atrophy (N = 18), (4) age 70-89, with atrophy (N = 16). Results of analyses of variance indicate that Digit-Span is affected by cerebral atrophy but not by age, while Paired-Associate Learning is affected by both age and cerebral atrophy. No interaction effect between age and cerebral atrophy was found for either task. These results are discussed within the context of previous research, and implications for both models of memory and theories of the effects of cerebral atrophy in different ag groups are suggested.

Age Factors↗
PubMed1979

Texture discrimination and the analysis of proximity.

A major theory of early visual processing has recently been proposed by Marr, which considers a number of aspects of visual perception in great detail, including grouping and texture discrimination. New phenomena associated with texture discrimination are described and experiments reported which allow a preliminary comparison of Marr's theory, as it applies to texture discrimination, with more established theories such as that due to Julesz. One experiment produced results which are clearly consistent with Marr's account, but the ability of his theory to deal with additional data on region suppression is not established. The theory of the analysis of proximity relations proposed by Fox offers a broadly satisfactory account of many texture perception results, while relying on the more fundamental parts of Marr's theory of primitive visual processes to deal with the remainder. A further attraction of proximity analysis is that it may shed new light on the classical paradox of symmetry perception. Some ways in which the preliminary proximity analysis model is incomplete are discussed, and it is concluded that development of the model may be profitable for theories of early visual processing.

Discrimination, Psychological↗
PubMed1978

Stimulation of duodenal and ileal absorption of phosphate in the chick by low-calcium and low-phosphorus diets.

The intestinal absorption of phosphate has been studied in vivo in the chick using ligated segments of duodenum and ileum. Feeding diets low in calcium (0.1%) and/or low in phosphorus (0.25%) caused an increase in the absorption of phosphate from both the duodenum and ileum. These changes are consistent with a putative increase in the renal production and mucosal uptake of 1,25-dihydroxycholecalciferol.

Animals↗
PubMed1978

Proton nuclear magnetic resonance studies of hemoglobin Providence (beta82EF6 Lys replaced by Asn or Asp): a residue involved in anion binding.

High-resolution proton nuclear magnetic resonance studies of hemoglobins Providence-Asn (beta82EF6 Lys replaced by Asn) and Providence-Asp (beta82EF6 Lys replaced by Asp) show that different amino acid substitutions at the same position in the hemoglobin molecule have different effects on the structure of the protein molecule. Hemoglobin Providence-Asp appears to be in a low-affinity tertiary structure in both the deoxy and carbonmonoxy forms. Deoxyhemoglobin Providence-Asn has its beta heme resonance shifted downfield slightly from its position in normal adult hemoglobin; however, the tertiary structures of the heme pocket of hemoglobins A and Providence-Asn are very similar when both proteins are in the carbonmonoxy form. These results are consistent with the oxygen equilibrium measurements of Bonaventura, J., et al. [(1976) J. Biol. Chem. 251, 7563] which show that both Hb Providence-Asn and Hb Providence-Asp have oxygen affinities lower than normal adult hemoglobin, with Hb Providence-Asp having the lowest. Our studies of the effects of sodium chloride on the hyperfine shifted proton resonances of deoxyhemoglobins A, Providence-Asn, and Providence-Asp indicate that the beta82EF6 lysine is probably one, but not the only binding site for chloride ions.

Adult↗
PubMed1978

Predictors of mortality in presenile and senile dementia.

Forty-seven hospitalized patients with a diagnosis of presenile or senile dementia and without focal neurological disease of major systemic illness were given complete neurological, neuroradiological, and neuropsychological examinations. Mortality at one year after hospitalization was determined, 12 patients being lost to follow-up. Of the remaining 35 patients, 19 were alive and 1l had died. These groups did not differ in age, education, length of dementia history, sex, race, or degree of cerebral atrophy (by computerized tomography). Significant differences were found in degree of electroencephalographic abnormality and in 8 of 14 cognitive measures, the the largest single difference being on a test of expressive language. Discriminant function analysis made with the cognitive measures as dependent variables yielded a correct prediction (classification analysis) of mortality in all but 1 case (97% accuracy). These results suggest that (1) degree of functional brain impairment rather than degree of cerebral atrophy may be the more important influence on mortality in dementia patients without focal lesions, (2) short-term survival may be accurately predicted in such patients by tests of cognitive functioning, and (3) expressive language deficit in such patients may indicate a particularly poor prognosis for survival.

Aged↗
PubMed1978

The in vitro metabolism of 25-hydroxycholecalciferol by pig kidney: effect of low dietary levels of calcium and phosphorus.

1. Homogenates of pig kidney incubated in vitro convert 25-hydroxycholecalciferol to the dihydroxymetabolites almost as efficiently as homogenates of chick kidney under similar conditions. 2. The cortex of the kidney carries out this conversion more efficiently than does the medulla. 3. Kidneys from pigs given low calcium or low phosphorus diets produce about 40% more 1,25-dihydroxycholecalciferol than those from pigs given diets containing normal levels of Ca and P.

Animals↗