Biomedical subjects

K A Erickson

Publications and source records attributed to K A Erickson.

28 records · Page 2Linked to original sources

PubMed1984

Intercomparison of seven radioimmunoassay kits and a fluorescence polarization immunoassay kit for digoxin.

Samples from 33 patients being treated with digoxin and three concentrations of control material were analyzed for this drug by use of seven radioimmunoassay (RIA) kits and an automated fluorescence polarization immunoassay (FPIA) system. CVs ranged from 2.4 to 6.4% for the FPIA system and from 4.6 to 7.4% for two RIA methods. In the analysis of between-method variability of RIA kits, CVs ranged from 6.1 to 33.2%. We compared each RIA kit with the other six RIA kits (I), as well as each RIA kit with the FPIA system (II). Correlation coefficients were greater than or equal to 0.96 in all cases. Slopes ranged from 0.82 to 1.20 for comparison I and from 0.86 to 1.01 for comparison II. For the FPIA system, analytical recovery of digoxin ranged from 94 to 104%. For the RIA methods we examined, analytical recoveries ranged from 113 to 135%. Analysis time is shorter and precision is greater for the FPIA system than for the RIA methods.

Digoxin↗

PubMed1983

Echothiophate iodide cataracts in monkeys. Occurrence despite loss of accommodation induced by retrodisplacement of ciliary muscle.

Five cynomolgi underwent unilateral 360 degrees ciliary muscle retrodisplacement. Beginning several months later, they received 150 to 210 micrograms of echothiophate iodine topically once daily in both eyes for five months. In all eyes anterior and posterior subcapsular lens opacities developed that were characteristic of those caused by echothiophate. There were no apparent differences in biomicroscopic appearance or time course of the cataracts between eyes with or without retrodisplaced ciliary muscles. Since eyes with retrodisplaced ciliary muscles accommodate only minimally in response to echothiophate, possible mechanical stress on the lens due to sustained, intense accommodation cannot explain echothiophate cataractogenesis.

Accommodation, Ocular↗

PubMed1983

Effect of repeated anterior chamber perfusion on intraocular pressure and total outflow facility in the cynomolgus monkey.

Total outflow facility was determined by two-level constant pressure perfusion of the anterior chamber in surgically virgin, aniridic, and ciliary muscle disinserted cynomolgus monkey eyes 6 to 13 times at 1- to 2-month intervals over periods of 8 to 24 months. Facility decreased approximately 15 to 20% between consecutive thirds of the perfusion history, independent of eye type. The facility decreases were too large to be explained by decreased uveoscleral facility or pseudofacility, and were not mediated by the iris, ciliary muscle, or gonioscopically or ultrastructurally apparent chamber angle alterations. They most probably reflected functional alterations in the trabecular meshwork/inner wall of Schlemm's canal. Intraocular pressure as measured by applanation tonometry did not increase progressively, most probably due to a decreased rate of aqueous humor formation.

Animals↗

PubMed1982

A comparison of the biological properties of androst-5-en-3 beta-ol, a series of (20R)-n-alkylpregn-5-en-3 beta-ols and 21-isopentylcholesterol with those of cholesterol.

The delta 5-sterol, androst-5-en-3 beta-ol, which has no side chain at C-17, did not permit molting of the insect Heliothis zea, growth of either the protozoan Tetrahymena pyriformis, or the yeast Saccharomyces cerevisiae adapted to anaerobic conditions, nor was the sterol esterified by a mammalian microsomal ACAT preparation. However, the sterol did form a liposome with egg lecithin and, when fed to mice, did inhibit hepatic cholesterol synthesis. 21-Isopentylcholesterol also formed a liposome but neither supported the growth of the yeast nor was metabolized by the protozoan. When sterols, 20(R)-n-alkylpregn-5-en-3 beta-ols, with side chains of varying lengths were added to the medium of the protozoan, maximal esterification with fatty acids occurred with the 20(R)-n-pentyl derivative, and maximal inhibition of tetrahymanol formation occurred with the n-butyl, n-pentyl, and n-hexyl derivatives. In all of the assays cholesterol showed a positive response, either permitting molting or growth, being metabolized, inhibiting sterol or tetrahymanol synthesis, or forming a liposome.

Androstenols↗

PubMed1982

Effect of serotonin, histamine and bradykinin on outflow facility following ciliary muscle retrodisplacement in the cynomolgus monkey.

Cynomolgus monkeys with surgically untouched, aniridic, or ciliary muscle disinserted eyes underwent two-level constant pressure perfusion of the anterior chamber to determine total outflow facility before and after intracameral infusion of bradykinin triacetate (0.1, 1, 10 micrograms), histamine dihydrochloride (1, 10, 100 micrograms), or serotonin creatinine sulfate (1, 10, 100 micrograms). Bradykinin had no effect on facility in non-disinserted eyes, but significantly decreased facility in disinserted eyes at all three dosages. Histamine tended to decrease facility in non-disinserted and disinserted eyes at all three dosages, although the decrease was not consistently significant statistically. Serotonin tended to decrease facility in non-disinserted eyes at dosages of 10 and 100 micrograms, although the effects were not statistically significant; 1 microgram had no effect. In disinserted eyes, 1 microgram significantly decreased facility, while the higher dosages had no (10 micrograms) or less (100 micrograms) effect. No simple mathematical/physiological description of the drug-induced facility decreases could be formulated. The facility decreases could be due to drug effects directly on the outflow pathways or secondary to blood-aqueous barrier breakdown.

Animals↗

PubMed1982

Inhibition of hepatic cholesterol synthesis in mice by sterols with shortened and stereochemically varied side chains.

Mice were fed cholesterol or various other sterols for 26 hr, after which the amount of hepatic cholesterol synthesis was measured in a cell-free system. The following sterols were as effective as cholesterol itself in depressing the conversion of acetate into sterol: pregn-5-en-3 beta-ol, which lacks an isohexyl group on C-20; (E)-17(20)-dehydrocholesterol, in which the isohexyl group is fixed to the right; (E)-20(22)-dehydrocholesterol, in which C-23 is oriented away from the nucleus; and 20-epicholesterol. Moreover, when the isohexyl group was fixed to the left in (Z)-17(20)-dehydrocholesterol, this dietary sterol, identified in the liver, caused not only a depression in the conversion of both mevalonate and squalene into sterols. The incorporation of acetate into fatty acids was not depressed, nor did the (Z)-sterol appear to have a generalized effect on membranous enzymes, because the activity of glucose-6-phosphatase was unaffected. Thus, feedback inhibition was retained when the stereochemistry of cholesterol's side chain was drastically changed and even after the nearly complete removal of the side chain. This implies that the side chain is only minimally recognized by the mechanisms involved in feedback inhibition.

Animals↗

PubMed1982

Cytochalasin B and D dose-outflow facility response relationships in the cynomolgus monkey.

Total outflow facility was determined by two-level constant-pressure perfusion in cynomolgus monkeys for 30 to 40 min before and after intracameral infusion of cytochalasins B and D (CB, CD). CB and CD dose-facility response relationships were defined. CB doses of 0.1, 0.2, and 0.5 micrograms were subthreshold; 1, 2, 5 and 10 micrograms were effective, with 5 micrograms probably supramaximal. CD at 0.02 microgram was probably subthreshold; 0.1, 0.5, 1, 2.5, and 5 micrograms doses were effective, with 0.1 microgram being near or above maximum. Although the maximum effects of both agents were quantitatively similar, approximately doubling-starting facility, CD Was about 25 times more potent. Therefore, CB- and CD-induced facility increases are presumably due largely to interference with formation, structure, and function of actin filaments in the endothelial cells of the trabecular meshwork and inner wall of Schlemm's canal.

Animals↗

PubMed1981

Ocular biometry of the cynomolgus monkey.

Eight cynomolgus monkeys underwent ocular biometry. Body weight = 3.04 +/- 0.59 kg; horizontal corneal diameter = 9.79 +/- 0.47 mm; anterior corneal curvature = 59.20 +/- 1.51 diopters at 90 degrees, 58.81 +/- 2.18 diopters at 180 degrees, 0.40 +/- 1.03 diopters at 90 degrees-180 degrees; anterior chamber depth = 2.79 +/- 0.27 mm; lens thickness = 3.18 +/- 0.15 mm; vitreous cavity length = 11.25 +/- 0.51 mm; total internal axial length = 17.16 +/- 0.69 mm. Most of the ocular parameters were correlated with body weight.

Animals↗

PubMed1981

Comparative effects of three ocular perfusates on outflow facility in the cynomolgus monkey.

Total aqueous outflow facility was determined by two-level constant pressure perfusion of the anterior chamber for 90 minutes in both eyes of cynomolgus monkeys. Each monkey received Bárány's solution (B, containing no bicarbonate, ascorbate, lactate, urea, sulfate, or amino acids) in one eye and either Gaasterland's (G, containing bicarbonate, ascorbate, lactate, urea, sulfate, and amino acids; 8 monkeys) or modified Gaasterland's (GM, containing ascorbate, lactate, urea, sulfate, and amino acids, but no bicarbonate; 8 monkeys) solution in the other. Starting facility tended to be slightly lower and to exhibit more interanimal variability with G than with B or GM. Perfusion with all three solutions caused a time-dependent facility increase. Facility with G increased approximately 60% during the second 30 minutes, compared to about 15% with B and GM; the difference may have been related to alkalinity and pH instability of G. There were no apparent differences during the final 30 minutes. Solutions containing ascorbate, bicarbonate, lactate, urea, sulfate, and various amino acids conserve facility no better under our perfusion conditions than the much simpler Bárány's solution, indicating that lack of these compounds does not cause the time-dependent facility increase.

Amino Acids↗

PubMedDate not supplied

Storybook-based communication intervention for girls with Rett syndrome and their mothers.

PURPOSE: Storybook reading provides a natural language learning context in which to support early symbolic communication. In this study, we explored the impact of (1) resting hand splints, (2) light tech augmentative communication systems such as voice-output devices and symbols, and (3) very basic parent training on the symbolic communication and labelling behaviours of six girls with Rett syndrome. METHOD: Mothers and daughters were videotaped as they read familiar and unfamiliar storybooks in their homes. RESULTS: Group and individual data collected from the six girls indicated that they became more active and successful participants in the interactions during storybook reading. The girls employed a wider range of communication modes and increased the frequency of their labelling. Familiar storybook reading encouraged greater symbolic communication than unfamiliar storybooks in half the girls. CONCLUSION: This study suggests that motivated parents may not require expensive technologies or lengthy training in order to enhance their children's early communication and participation in storybook reading.

Adult↗