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Biomedical subjects

C F Reed

Publications and source records attributed to C F Reed.

At least 19 recordsLinked to original sources
PubMed1984

Terrestrial passage theory of the moon illusion.

Theories of the celestial, or moon, illusion have neglected geometric characteristics of movement along and above the surface of the earth. The illusion occurs because the characteristics of terrestrial passage are attributed to celestial passage. In terrestrial passage, the visual angle subtended by an object changes discriminably as an essentially invariant function of elevation above the horizon. In celestial passage, by contrast, change in visual angle is indiscriminable at all elevations. If a terrestrial object gains altitude, its angular subtense fails to follow the expansion projected for an orbital course: Angular diminution or constancy is equivalent to distancing. On the basis of terrestrial projections, a similar failure of celestial objects in successive elevations is also equivalent to distancing. The illusion occurs because of retinal image constancy, not--as traditionally stated--despite it.

Astronomical Phenomena↗
PubMed1982

Maturation and d-amphetamine-induced changes in web building.

Webs of Araneus diadematus Cl. were obtained under drugged (dextroamphetamine) and control conditions at three age-periods in the development of the spider from juvenility to sexual maturity. Although certain features of construction are affected in all periods and some exhibit differential effects with age, it was not possible to separate the latter from changes in body mass between periods.

Age Factors↗
PubMed1968

Phospholipid exchange between plasma and erythrocytes in man and the dog.

The turnover of the four major erythrocyte phospholipids has been studied with (32)P, both in vivo and in vitro, in man and the dog. Phosphatidyl serine and phosphatidyl ethanolamine appeared to be stable erythrocyte lipids in both species. Turnover of the phosphate moiety of lecithin and sphingomyelin in the circulating erythrocytes of these two species seems entirely due to an exchange of the whole molecule with the corresponding plasma compound. Exchangeable and nonexchangeable pools of these two cellular lipids were found. In man about 60% of erythrocyte lecithin is exchangeable. The 12 hr fractional turnover of this pool is approximately 13%. Only 30% of the sphingomyelin in human cells appeared exchangeable; this portion had a 12 hr fractional turnover of about 14%. Similar results were obtained in the dog except that in this species about 75% of the erythrocyte sphingomyelin was exchangeable. Inorganic (32)P was not incorporated into any of the four major phospholipids in either species. The present findings aid in estimating quantitatively the effect of plasmaerythrocyte lipid exchange on red blood cell phospholipids.

Chromatography, Paper↗
PubMed1968

An inherited molecular lesion of erythrocyte pyruvate kinase. Identification of a kinetically aberrant isozyme associated with premature hemolysis.

Atypical cases of heritable hemolytic anemia have been noted that conform clinically and biochemically to anemias of the pyruvatekinase (PK)-deficient type, except for the presence of apparently adequate quantities of erythrocyte-PK activity by the usual assay procedure. Investigations of four such anomalous cases, occurring in two unrelated families, are presented. Erythrocytes contained a kinetically aberrant isozyme of pyruvate kinase (PK(2)). Michaelis constants for the pathologic isozyme relative to phosphoenolpyruvate were over 10-fold greater than control values, but no kinetic abnormality was evident for the second substrate, adenosine diphosphate. PK(2) exhibited a pH optimum almost 1 U lower than the wild enzyme form (PK(1)). Significant differences were also evident in the functional stabilities of the isozymes. Leukocytes were unaffected. Family studies revealed paternal heterozygosity for quantitative PK deficiency of the usual type. Clinically normal maternal relatives and some siblings demonstrated intermediate deviations in erythrocyte-PK kinetics and reaction characteristics compatible with coexistence of normal PK(1) and kinetically abnormal PK(2). Hemolytic anemia in the propositi appeared to require simultaneous inheritance of the gene governing PK(2) production and its presumed allele resulting in quantitative PK deficiency. Both genetic defects were traced through three generations, the defective gene in both instances apparently resident on autosomes.A revision of the PK assay technique is suggested, since catalytic inefficiency of PK(2) was manifested only at low substrate concentrations and was therefore undetectable at the relatively high phosphoenolpyruvate levels employed in the conventional assay.

Adenine Nucleotides↗
PubMed1968

Incorporation of orthophosphate-32P into erythrocyte phospholipids in normal subjects and in patients with hereditary spherocytosis.

The in vitro incorporation of inorganic (32)P into erythrocyte phospholipids has been studied in normal subjects and in splenectomized patients with hereditary spherocytosis (HS). Phosphatidic acid (PA) was the only lipid measurably labeled in both kinds of cells. The actual turnover rate of PA phosphate was determined by simultaneously isolating inorganic phosphate (P(i)) and adenosine triphosphate (ATP) and determining their specific activities. This turnover is very small: 1.3 mumoles P/liter of erythrocytes per hr in normal cells and 4.0 mumoles P in HS erythrocytes when either ATP or cellular P(i) is considered the immediate precursor. This value represents less than 0.1% of the total membrane lipid phosphate. Incorporation of added (32)P(i) into the other phosphatides, including phosphatidyl serine, was essentially zero in both kinds of cells. The effects of stimulation and inhibition of active cation transport, metabolic depletion, and extracellular phosphate concentration on both the degree of labeling and the actual turnover of PA phosphate were studied. In any given experiment, the degree of labeling of PA depended on the specific activities of the other intracellular phosphates (P(i) and ATP). The actual turnover rate of PA phosphate, however, did not vary with active transport or metabolic depletion. The greater turnover of PA phosphate in HS erythrocytes may be due to the somewhat younger age of these cells. The results suggest that the very low turnover of PA phosphate in erythrocytes is mediated by nonspecific enzyme reactions, and that it is quantitatively insignificant in both normal and HS erythrocytes. The results also emphasize the importance of measuring intracellular phosphate precursors in any study evaluating cellular phospholipid turnover from added (32)P(i).

Adenosine Triphosphate↗
PubMed1967

Erythrocyte energy metabolism in hereditary spherocytosis.

The incorporation of extracellular orthophosphate-(32)P into cellular ATP, 2,3-diphosphoglyceric acid, and inorganic phosphate has been measured over a period of 6 hours in vitro in red blood cells from normal subjects and from patients with hereditary spherocytosis who had undergone splenectomy. The pattern of labeling of the intracellular compounds was found to be the same in both types of red blood cells, as reported by other workers using much shorter periods of incubation. In addition, in the present study it was possible to compare the net flux of extracellular phosphate into ATP between the two groups of erythrocytes. These latter results suggest that the actual turnover rate of ATP was not abnormal in these patients with hereditary spherocytosis.

Adenosine Triphosphate↗