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Biomedical subjects

C Mitchell

Publications and source records attributed to C Mitchell.

At least 181 records · Page 10Linked to original sources
PubMed1979

Reflection-impulsivity and the evaluation process.

The relationship between reflection-impulsivity, hypothese generation and testing, and evaluation of the quality of one's own solutions was explored in the framework of Kagan's theory. The Matching Familiar Figures test (MFF) and a pattern-matching task were administered to 94 children from 8-0 to 11-11 years. Multiple regression analyses and analyses of variance showed that children who were inaccurate on the MFF were more likely to offer a solution on the pattern-matching task before they had sufficient information to guarantee a correct solution and to make errors despite sufficient information to have avoided those errors. Thus reflection-impulsivity as measured by the MFF were related to 2 other measures of the evaluation process on another visual match-to-sample task. Only 1 of 3 hypothesis-testing variables was significantly related to MFF performance, and that relationship was rather small.

Child↗
PubMed1977

Frequency effects of temporary N1 depression following acoustic overload.

The effect of acoustic overload on the N1 potential at different frequences was determined. The conditions of overstimulation were such as to produce temporary effects. The results of the study were: (1) the N1 potential was substantially depressed by acoustic overloads that did not alter the alternating current (AC) cochlear potential; (2) the maximum N1 depression was at one-half octave above the overstimulation frequency; (3) there was no N1 depression at frequencies below the frequency of overstimulation; and (4) the N1 depression recovered within 24 hours.

Action Potentials↗
PubMed1977

Audiograms derived from the brain stem response.

Nineteen normal and 22 hearing impaired subjects were used in this study. Thresholds were determined by the following methods: 1. behavioral continuous tone, 2. behavioral tone burst, and 3. the brain stem electric response (BER) with tone bursts. A comparison of the BER thresholds with the behavioral thresholds are made for each subject. The difference between these three measures of threshold suggests that audiograms can be derived from the brain stem response threshold. The derived audiogram compares favorably with conventional audiograms. However, it must be remembered that the brain stem response is not hearing.

Auditory Threshold↗
PubMed1977

Patient education and intrauterine contraception: a study of two package inserts.

In July 1975 the Food and Drug Administration proposed a patient information package insert for all women considering use of an intrauterine device. In the same year we also prepared a brochure to be given to women considering use of a specific intrauterine contraceptive, the PROGESTASERT system. To compare these information sources for the patient, we surveyed by mail 253 women who are or had been PROGESTASERT system users. Each woman received either the FDA or our own prepared version. Comprehension of the two inserts was generally comparable, but readers of our insert found its informational content more complete. The survey findings affirmed the desirability of providing the patient with an educational brochure to be read prior to IUD insertion.

Attitude↗
PubMed1976

Interaction between bronchoconstrictor stimuli on human airway smooth muscle.

In healthy human subjects, the simultaneous aerosol administration of histamine and methacholine results in a pronounced decrease in maximum flow rates on partial expiratory flow-volume (PEFV) curves. When given alone in the same concentrations, these drugs produced no or minimal decreases in flow rates. The results suggest an interaction of histamine and cholinergic stimuli on airway smooth muscle (ASM). This mechanism might explain many experiments where vagal blockade diminished or abolished ASM response to histamine and other stimuli, simply by interfering with histamine-cholinergic interaction at the ASM level. These findings confirm similar findings of animal in vitro experiments. The experiments clearly confirm the sensitivity and value of assessing drug effects prior to a deep breath. Flow-rate changes after a full inspiration, taken from the maximum expiratory flow-volume (MEFV) curve, show either no relationship to the concentration of inhaled methacholine or significantly less effect than that seen on the PEFV curve.

Adult↗
PubMed1975

Continuous negative chest-wall pressure as therapy for severe respiratory distress in older children.

Continuous negative chest-wall pressure (CNP) was used to treat five children, 4 to 11 years of age, who had progressively severe respiratory distress caused by Pneumocystis carinii penumonitis. After initial improvement, two patients developed progressive increases in respiratory rate, alveolar-arterial oxygen gradient, intrapulmonary right-to-left shunt, and hypoxia. The disease ended fatally in both. The remaining three patients continued to improve and recovered from their pulmonary disease. These results show that CNP therapy provides an effective means of improving arterial oxygenation in spontaneously breathing older children, just as in neonates, without the need for endotracheal intubation, prolonged sedation, and muscle relaxants.

Acid-Base Equilibrium↗
PubMed1973

Transfection of Escherichia coli spheroplasts. II. Relative infectivity of native, denatured, and renatured lambda, T7, T5, T4, and P22 bacteriophage DNAs.

The change of infectivity of phage DNAs after heat and alkali denaturation (and renaturation) was measured. T7 phage DNA infectivity increased 4- to 20-fold after denaturation and decreased to the native level after renaturation. Both the heavy and the light single strand of T7 phage DNA were about five times as infective as native T7 DNA. T4 and P22 phage DNA infectivity increased 4- to 20-fold after denaturation and increased another 10- to 20-fold after renaturation. These data, combined with other authors' results on the relative infectivity of various forms of phiX174 and lambda DNAs give the following consistent pattern of relative infectivity. Covalently closed circular double-stranded DNA, nicked circular double-stranded DNA, and double-stranded DNA with cohesive ends are all equally infective and also most highly infectious for Escherichia coli lysozyme-EDTA spheroplasts; linear or circular single-stranded DNAs are about 1/5 to 1/20 as infective; double-stranded DNAs are only 1/100 as infective. Two exceptions to this pattern were noted: lambda phage DNA lost more than 99% of its infectivity after alkaline denaturation; this infectivity could be fully recovered after renaturation. This behavior can be explained by the special role of the cohesive ends of the phage DNA. T5 phage DNA sometimes showed a transient increase in infectivity at temperatures below the completion of the hyperchròmic shift; at higher temperatures, the infectivity was completely destroyed. T5 DNA denatured in alkali lost more than 99.9% of its infectivity; upon renaturation, infectivity was sometimes recovered. This behavior is interpreted in terms of the model of T5 phage DNA structure proposed by Bujard (1969). The results of the denaturation and renaturation experiments show higher efficiencies of transfection for the following phage DNAs (free of single-strand breaks): T4 renatured DNA at 10(-3) instead of 10(-5) for native DNA; renatured P22 DNA at 3 x 10(-7) instead of 3 x 10(-9) for native DNA; and denatured T7 DNA at 3 x 10(-6) instead of 3 x 10(-7) for native DNA.

Coliphages↗