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Biomedical subjects

C Mitchell

Publications and source records attributed to C Mitchell.

At least 163 records · Page 9Linked to original sources
PubMed1982

Postoperative respiratory morbidity: identification and risk factors.

Two hundred consecutive patients admitted for general surgery were studied prospectively to evaluate the contribution of risk factors to postoperative respiratory morbidity (PORM). PORM was expressed both in terms of individual clinical features present on the second postoperative day (when the incidence was greatest), and as an aggregate score incorporating many clinical features. The importance of recognised risk factors, such as previous respiratory disease, cigarette smoking, upper abdominal procedures and the duration of surgery was confirmed, in that these factors were associated with some of the individual clinical features of PORM. The relative importance and independent contribution of these risk factors were assessed by their association with the aggregate score. A naso-gastric tube (NGT) present for 24 hours postoperatively was the factor more associated with PORM. The NGT identified patients at risk more clearly than, and independently of, the next most important factor, upper abdominal surgery. The duration of surgery did not contribute to PORM after the influence of NGT and site of surgery had been considered. Previous respiratory disease predisposed to PORM, and was best identified by, in order of importance, an observed productive cough, a reduced one second forced expiratory volume, and purulent sputum. After the incidence of these factors had been considered, cigarette smoking and a history of a chronic productive cough did not contribute further to PORM.

Abdomen↗
PubMed1981

Prevalence of respiratory morbidity in Brisbane waterside workers. A study of possible asbestos-related disease.

Ninety-eight Brisbane waterside workers who had been exposed to several dusts, particularly that of asbestos fibre, were studied. Forty-nine subjects complained of dyspnoea while walking uphill, 46 had basal endinspiratory crepitations, and chest X-ray films showed small irregular opacities in 41 subjects and pleural abnormalities in 27 subjects. Internal comparisons showed that ventilatory function was correlated significantly with duration of employment on the wharves, independently of the effect of age and total cigarette consumption. Forced vital capacity decreased by 20 mL/year on wharves, and one-second forced expiratory volume by 34 mL/year, in excess of the age-related decrease. These findings suggest that these workers have developed parenchymal lung disease probably related to asbestos-dust exposure on the wharves.

Adult↗
PubMed1981

DNA modification in rat lungs following intratracheal or subcutaneous administration of 4-nitroquinoline-1-oxide, benzo[a]pyrene or 2-aminoanthracene.

Benzo[a]pyrene (BP)-, 2-aminoanthracene (2AA)- and 4-nitroquinoline-1-oxide (4NQO)-mediated DNA modification were investigated in rat lungs by using alkaline sucrose gradient sedimentation. The exposure-route, the physicochemical nature of the administered compound and the number of treatments were all important in determining the extent of DNA modification. 4NQO produced qualitatively similar modification whether instilled intratracheally (i.t.) as a suspension or injected subcutaneously (s.c.) in a soluble form. BP and 2AA produced no DNA alteration when injected s.c; they did, however, modify DNA sedimentation when instilled as a suspension, but not until 24 h after treatment. Furthermore, BP caused no DNA modification at any sampling time when instilled in a lipid solvent. In contrast to the DNA modification observed at 24 h after a single i.t. treatment with a BP suspension, no such alteration was detected 12 or 24 h after the last of 5 similar daily treatments. These results are discussed with respect to mechanisms of differential transport, clearance and metabolism of administered carcinogens.

4-Nitroquinoline-1-oxide↗
PubMed1980

Selected events following insertion of the Progestasert system.

The incidences of selected events were analyzed following insertion of the PROGESTASERT intrauterine progesterone contraceptive system (IPCS) and following its reinsertion after one year of use. Reinsertion did not interrupt the stabilizing or declining trends in incidences of P.I.D., removals for bleeding/pain, removals for other medical reasons, unplanned pregnancies, moderate/severe menstrual cramps and bleeding, and premenstrual/intermenstrual cramps. Comparison of the incidence of P.I.D. in the U.S. population with postinsertion incidence of P.I.D. in IPCS users indicates that the IPCS does not increase the likelihood that a woman will have P.I.D. over the likelihood that she would have it without use of the IPCS. The incidences of expulsions and intermenstrual spotting and bleeding rose temporarily after reinsertion to about half their previous peaks and then diminished markedly within two months, reverting to the levels and favorable patterns of change established during the first year.

Female↗
PubMed1980

Tuning curves of cochlear and brainstem responses in the guinea pig.

A tone-on-tone masking paradigm was used to determine tuning curves of cochlear and brainstem responses in the guinea pig. The tuning curves are considered to be a measure of the frequency specificity of these potentials. Calculated Q10 values are used in an indicator of the sharpness of tuning of these potentials. The tuning curves of cochlear and brainstem responses were found to be similar with both showing considerable frequency specificity.

Animals↗
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↗