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Biomedical subjects

R C Marshall

Publications and source records attributed to R C Marshall.

At least 55 records · Page 3Linked to original sources
PubMed1982

The tryptophan-rich keratin protein fraction of claws of the lizard Varanus gouldii.

1. Claw keratin of the lizard, Varanus gouldii, is composed mainly of 13,000 mr proteins rich in glycine and cystine. This study deals with a tryptophan-rich group of about 20 constituent proteins comprising about one-third of the mass. 2. As S-carboxymethylkerateines, these proteins were separated by fractional precipitation and gel filtration, then characterized by amino acid analysis, end group analysis, electrophoresis and ultracentrifugation. 3. It is considered that the majority of lizard claw proteins are more closely allied to those of avian beak and claw than feather proteins. 4. Claw keratin also contains minor proteins which resemble mammalian keratin high-tyrosine proteins.

Amino Acids↗
PubMed1982

Changes in the proteins of wool following treatment of sheep with epidermal growth factor.

Administration of epidermal growth factor (EGF) extracted from mouse submaxillary gland to Merino sheep resulted in a temporary inhibition of the activity of the wool follicles. Subsequently, either complete discontinuities appeared in the fibers resulting in shedding of the entire fleece, or incomplete, in which case the fleece was retained but bore a zone of weakness. The protein composition of the first sample of wool harvested from 1 sheep following infusion for 66 hr with 27.5 mg EGF (0-2 weeks posttreatment) was similar to pretreatment wool. This represented wool fibers which were already present in the follicles at the beginning of infusion. Thereafter, the composition of the wool changed progressively, reaching a maximum divergence from the control in the 3-4 week regrowth period followed by a return to normal by about 10 weeks. Over this period the content of high-sulfur proteins first rose from an initial 19% to a maximum of 30%, then returned to 19%, while the high-tyrosine protein content initially decreased from 12% to 5% and then slowly increased to 12%. In addition to changes in overall protein composition, two-dimensional electrophoresis revealed alterations in the proportions of some individual protein components. These changes were similar to those observed with many other wool growth inhibitors. Smaller doses of EGF (5.8 and 2.9 mg but not 1 mg) had similar effects on wool composition but these were of lower magnitude and there was a delay in reaching a maximum response. Even after 16-18 weeks the wool from these treated sheep differed slightly in composition from the pretreatment samples.

Animals↗
PubMed1982

In vitro growth and differentiation of epithelial cells derived from post-embryonic hair follicles.

Cell aggregates formed during the first 2 days of culture of cells derived from hair follicle tissue of young rats. Aggregates occurred at an accelerated rate at higher cell densities, and contained a high proportion of epithelial cells although a variable proportion of mesenchymal (fibroblast) cells were present. Citrulline was detected in the cultured cell proteins. Electrophoretic analysis of the proteins showed the presence of hair cortical keratin in the cultures, but these proteins were not synthesized during the culture period, in conflict with previous findings. Protein synthesized by the cultured cells was not of inner root sheath or epidermal origin and the only protein which could be identified was actin. It is concluded that the present culture system is unsuitable for the study of keratinization as occurs in the intact hair follicle.

Animals↗
PubMed1981

Identifying behavior associated with verbal self-corrections of aphasic clients.

The purposes of this study were to define certain behaviors associated with verbal self-correction efforts of aphasic clients and to determine the accuracy with which these behaviors might be identified by clinical observers. Seven explicit definitions were written for behaviors associated wih aphasic clients' self-correction attempts on single-word and short-answer language production tasks. To determine the accuracy with which defined behaviors could be identified, observers (N = 7) were asked to view 400 randomly selected speech samples and to code the type of self-correction event for each sample. The accuracy of these judgments was ascertained by calculating the percentages of observers' agreements with judgments made previously by the experimenters. Results showed observers were able to identify explicitly defined behaviors at levels of accuracy ranging from 73%--99%. When observers' judgments did not agree with those of the experimenters, inaccuracies tended to be logical and to cluster in particular categories. Findings suggest a need for further study of behaviors associated with aphasic individuals' self-correction efforts, particularly with reference to the significance of these behaviors to recovery from aphasic, and to aphasic symptomatology in general.

Aphasia↗
PubMed1981

The effects of topical and systemic glucocorticosteroids on DNA synthesis in different tissues of the hairless mouse.

Two topical corticosteroids, clobetasol propionate and clobetasone butyrate, have been studied in hairless mice for their effects on DNA synthesis in the epidermis, thymus and spleen. Following topical application, both clobetasol propionate and clobetasone butyrate showed significant activity at the site of application throughout the range of concentrations tested (20 microliters; 0.0001-0.1%; 20 ng to 20 micrograms). However, whereas 20 ng clobetasol propionate also elicited significant effects in the distal (untreated) epidermis and the thymus, more than 2 micrograms of clobetasone butyrate were required to produce similar effects in these tissues. This finding was supported by the results obtained following intravenous administration of equivalent doses (0.01 and 0.001%; 200 microliters dose) of the same two steroids. Only clobetasol propionate showed significant activity in the epidermis and thymus. Clobetasone butyrate showed slight, non-significant effects in the epidermis at the highest concentration (200 microliters; 0.01%), but not in the thymus or spleen. An unexpected finding was that the effects following intravenous injection were generally lower than those following topical application. In conclusion, these results establish that (a) effects on DNA synthesis in the epidermis at a site distal to the application site are indicative of systemic activity from topically applied corticosteroids, (b) the thymus is especially sensitive to corticosteroids eliciting systemic effects and (c) an equivalent dose of a topical corticosteroid administered intravenously produces less inhibition of thymic and epidermal DNA synthesis than the same dose applied topically.

Administration, Topical↗
PubMed1981

Effect of oral propranolol on rest, exercise and postexercise left ventricular performance in normal subjects and patients with coronary artery disease.

The effect of beta-adrenergic blockade with oral propranolol on resting, exercise and postexercise ventricular performance was evaluated using multiple-gated equilibrium cardiac blood and pool images in normal volunteers and patients with coronary artery disease. Propranolol produced no detectable effect on basal left ventricular function in normal subjects at doses producing intermediate (160 mg propranolol/day) and maximal (434 +/- 99 mg propranolol/day) beta blockade and in patients with coronary artery disease at clinically effective antianginal doses (162 +/- 47 mg propranolol/day). During exercise, a dose-related, negative inotropic effect was observed in normal subjects: 160 mg propranolol/day produced a small but statistically insignificant decline in exercise left ventricular performance, whereas maximal beta blockade significantly depressed the left ventricular response to exercise. In patients with coronary artery disease, propranolol's effect on exercise ventricular performance depended on the presence or absence of ischemic dysfunction during exercise. In patients with an ischemic functional response to exercise, propranolol significantly improved regional and global performance during and after exercise; in coronary artery disease patients with a normal response to exercise, propranolol had no significant effect on exercise and postexercise ventricular function. These results imply increased sensitivity to the effects of beta blockade in ischemic myocardium. In coronary artery disease patients with an abnormal response to exercise and in normal volunteers during beta blockade, propranolol's effect on exercise left ventricular performance was independent of changes in ventricular preload and after load related to heart rate and blood pressure.

Administration, Oral↗
PubMed1980

Effects of scheduling on the communicative assessment of aphasic patients.

This study determined the influence of morning and afternoon scheduling on the assessment of communicative skills of aphasic patients. Eight short-term (3 to 9 months post-onset) and eight long-term (12 or more months post-onset) aphasic subjects were administered 11 tests from the Porch Index of Communicative Ability (PICA) at specified times in the morning (A.M.) and afternoon (P.M.). Order of scheduling (A.M. first, P.M. second; P.M. first, A.M. second) was determined randomly but balanced between groups. Results indicated an absence of significant main effects for onset, scheduling, and test order; however, significant interactions between the scheduling and test-order factors were evidenced on the naming and auditory identification tests and on all overall measures. Analyses of these interactions revealed that patients scheduled first in the A.M. decreased their mean scores when assessed a second time in the P.M., whereas those scheduled first in the P.M., increased their scores when seen a second time in the A.M. Findings suggest that aphasic patients can be expected to do better on morning than afternoon assessments regardless of the order in which they are scheduled. Clinically, this indicates a need for consistency in the scheduling of periodic assessments for individual aphasic patients.

Adult↗
PubMed1980

Genetic variation in the proteins of human nail.

In a survey of the proteins from human nail, genetic variation has been observed in both the low-sulfur and high-sulfur protein fractions. The low-sulfur proteins were examined by polyacrylamide gel electrophoresis at pH 7 in the presence of sodium dodecyl sulfate, whilst the high-sulfur proteins were characterized by gel electrophoresis at pH 2.6 in 3 M urea. Of 106 samples of apparently normal nail, 69% showed a characteristic pattern of 3 major low-sulfur and 5 major high-sulfur proteins. The remaining samples showed an additional high-sulfur band, and about half of these samples also manifested an additional major low-sulfur band. The proportion of nail samples containing the variant proteins was much higher in some families. Two-dimensional eletrophoresis of the low-sulfur proteins showed five major low-sulfur components in the normal nail with an additional component in the variant sample. Peptide maps of the proteins showed that the additional protein was sufficiently different in amino acid sequence to the other proteins to indicate that a mutation in a structural gene had not occurred. In the high-sulfur protein fractions, over 30 proteins were observed in the two-dimensional electrophoretic patterns and there were at least 3 additional components in the variant fraction.

Amino Acids↗
PubMed1980

Aphasic adults and their decisions on driving: an evaluation.

This study evaluated the propriety of decisions by aphasic adults to avoid or to return to driving following a cerebrovascular accident. A comparison was made of a rehabilitation team's assessments of driving skills with a group of 10 aphasic adults who had chosen to return to driving without professional consultation and 10 aphasic adults who had not returned to driving. The Fisher Exact Probability Test found that the team-assigned driver and nondriver groupings agreed with the patients' own groupings with the relationship significant at p less than 0.005. This suggested patients had appropriately judged their own compentency to drive. Discriminant analysis of variables tested by the team suggested language performance alone was not the most cogent indicator for driving candidacy.

Adult↗
PubMed1980

Aphasic patients in a rehabilitation program: scheduling speech and language services.

Eleven 10-item tests from the Porch Index of Communicative Ability (PICA), were administered to 14 aphasic adults participating in a rehabilitation program. Tests were given once in the morning and once in the afternoon. Results indicate that overall communicative functioning was significantly higher for morning assessments, although some individual patients did better in the afternoon. The primary implication of these results is the importance of consistency in scheduling patient contacts when measuring the effects of treatments rendered. Considerations in determining optimum schedules and aiding individual patients in compensating for reduced efficiency due to time of day are discussed.

Adult↗
PubMed1979

The effects on epidermal DNA synthesis of topically applied cycloheximide.

An animal model for investigating topically applied epidermal cytotoxic drugs to determine optimum therapeutic doses and schedules is described. It is used here to examine the effects of cycloheximide on epidermal DNA synthesis, as measured by 3H-thymidine incorporation in vivo, in terms of dose/response and activity/time profiles and potential systemic toxicity.

Administration, Topical↗
PubMed1978

Assessment of cardiac performance with quantitative radionuclide angiocardiography: right ventricular ejection fraction with reference to findings in chronic obstructive pulmonary disease.

A reproducible noninvasive technique for measuring righ ventricular ejection fraction was developed using first pass quantitative radionuclide angiocardiography. Studies were obtained in the anterior position with a computerized multicrystal scintillation camera with high count rate capabilities. Right ventricular ejection fraction was calculated on a beat to beat basis from the high frequency components of the background-corrected right ventricular time-activity curve. In 50 normal adults, right ventricular ejection fraction averaged 55 percent (range of 45 to 65 percent). This radionuclide measure of right ventricular function was reproducible, with minimal inter- and intraobserver variability, and was sensitive to changes in inotropic state induced with isoproterenol. In 36 patients with chronic obstructive pulmonary disease, right ventricular ejection fraction ranged from 19 to 71 percent. All 10 patients with corpulmonale, as well as 9 additional patients, had an abnormal right ventricular ejection fraction. Arterial oxygen tension and forced expiratory volume were depressed significantly more in patients with abnormal right ventricular ejection fraction than in subjects with normal right ventricular function. There was no relation between abnormalities in right and left ventricular ejection fraction.

Adult↗
PubMed1978

Variability in sequential measures of left ventricular performance assessed with radionuclide angiocardiography.

The variability of left ventricular ejection fraction, normalized mean ejection rate and regional wall motion was evaluated from first pass quantitative radionuclide angiocardiograms obtained with a computerized multicrystal scintillation camera. Three radionuclide studies separated by an average of 4.3 days were obtained in each of 20 patients. Ejection fraction and ejection rate obtained on the first, second and third studies did not differ significantly. The mean (+/- standard deviation) variability of sequential ejection fraction measurement was 4.4 +/- 3.6 percent, and of sequential ejection rate was 0.56 +/- 0.47 sec(-1). Variations in measurements were not related to fluctuations in heart rate or blood pressure. Variability in ejection rate was significantly greater in patients with normal function than in those with abnormal function. Regional wall motion analysis was constant in 19 of 20 patients. Thus, sequential quantitative radionuclide angiocardiography allows reproducible serial assessment of left ventricular performance that can be performed with a low level of intrinsic variability.

Adult↗