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Biomedical subjects

C Sherrill

Publications and source records attributed to C Sherrill.

At least 19 recordsLinked to original sources
PubMed1996

Partitioning of a-factor analogues into membranes: analysis of binding and importance for biological activity.

Analogues of the a-factor mating pheromone of the yeast Saccharomyces cerevisiae were used to measure interactions of the pheromones with lipid vesicles and with isolated yeast membranes. The binding of the analogues of a-factor to vesicles and to membranes was best described as a partitioning of the pheromones into the lipid phase. The partitioning was enhanced by the negative surface potential of the membranes and was well described by the Gouy-Chapman theory of diffuse double layers. From the analysis of the binding of the pheromones to synthetic vesicles of known surface potential, effective charges and intrinsic partition coefficients were obtained for the pheromones. The information was used in subsequent experiments with yeast membranes to determine the intrinsic partition coefficients of the a-factor analogues and the charge density of the yeast membranes. Derivatives of a-factor with different alkyl chains in place of the normal C-terminal farnesyl displayed biological activity that paralleled the degree of partitioning of the pheromones into vesicles. Demethylation of the C-terminus decreased the partition coefficient by 6-fold and decreased the biological activity of the pheromone by greater than 2500-fold. The results show that a-factor can effectively partition into membrane bilayers and that the partitioning is probably involved in the subsequent recognition of the pheromone by the a-factor receptor.

4-Butyrolactone↗
PubMed1996

Glutathione amide and its perthiol in anaerobic sulfur bacteria.

Chromatium species produced the novel biological thiol glutathione amide, gamma-L-glutamyl-L-cysteinylglycine amide (GASH), when grown photoheterotrophically. GASH was largely converted to the corresponding perthiol during photoautotrophic growth on sulfide, suggesting that GASH may have a function in anaerobic sulfide metabolism. This unprecedented form of glutathione metabolism was probably present in anaerobic ancestors of modern cyanobacteria and purple bacteria.

Anaerobiosis↗
PubMed1996

Distribution of thiols in microorganisms: mycothiol is a major thiol in most actinomycetes.

Mycothiol [2-(N-acetylcysteinyl)amido-2-deoxy-alpha-D-glucopyranosyl- (1-->1)-myo-inositol] (MSH) has recently been identified as a major thiol in a number of actinomycetes (S. Sakuda, Z.-Y. Zhou, and Y. Yamada, Biosci. Biotech. Biochem. 58:1347-1348, 1994; H. S. C. Spies and D. J. Steenkamp, Eur. J. Biochem. 224:203-213, 1994; and G. L. Newton, C. A. Bewley, T. J. Dwyer, R. Horn, Y. Aharonowitz, G. Cohen, J. Davies, D. J. Faulkner, and R. C. Fahey, Eur. J. Biochem. 230:821-825, 1995). Since this novel thiol is more resistant than glutathione to heavy-metal ion-catalyzed oxidation, it seems likely to be the antioxidant thiol used by aerobic gram-positive bacteria that do not produce glutathione (GSH). In the present study we sought to define the spectrum of organisms that produce MSH. GSH was absent in all actinomycetes and some of the other gram-positive bacteria studied. Surprisingly, the streptococci and enterococci contained GSH, and some strains appeared to synthesize it rather than import it from the growth medium. MSH was found at significant levels in most actinomycetes examined. Among the actinobacteria four Micrococcus species produced MSH, but MSH was not found in representatives of the Arthrobacter, Agromyces, or Actinomyces genera. Of the nocardioforms examined, Nocardia, Rhodococcus, and Mycobacteria spp. all produced MSH. In addition to the established production of MSH by streptomycetes, we found that Micromonospora, Actinomadura, and Nocardiopsis spp. also synthesized MSH. Mycothiol production was not detected in Propionibacterium acnes or in representative species of the Listeria, Staphylococcus, Streptococcus, Enterococcus, Bacillus, and Clostridium genera. Examination of representatives of the cyanobacteria, purple bacteria, and spirochetes also gave negative results, as did tests of rat liver, bonito, Candida albicans, Neurospora crassa, and spinach leaves. The results, which indicate that MSH production is restricted to the actinomycetes, could have significant implications for the detection and treatment of infections with actinomycetes, especially those caused by mycobacteria.

Actinomycetales↗
PubMed1995

Synthesis and biological activity of fluorescent yeast pheromones.

The mating pheromones of Saccharomyces cerevisiae and derivatives of these pheromones have been synthesized and tested for biological activity in a solution-phase assay. The effects of native alpha-factor and a-factor on the growth of target cells in these assays were identical. A derivative of alpha-factor in which the amino terminus was modified with the fluorescent probe, 6-amino-N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)hexanoyl, was only slightly less active than the unmodified pheromone. Derivatives of a-factor that contain various alkyl groups in place of the farnesyl moiety of the native pheromone were also synthesized and tested for biological activity. A derivative in which the farnesyl moiety is substituted with an unbranched decyl group exhibited activity identical to that of the natural pheromone, whereas a derivative that contains an unbranched pentyl group exhibited significantly lower biological activity than native a-factor. The derivatives of a-factor have in addition been modified to incorporate 6-amino-N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) at the terminus of the alkyl chains. A derivative with the probe attached to a decyl chain displayed activity similar to that of the native pheromone, whereas the same modification on a pentyl chain produced a derivative with very low activity. The fluorescence spectra of the modified alpha-factor and a-factors were measured in methanol, aqueous solution, and aqueous solution containing phospholipid vesicles. The fluorescence of the probes depends on the environment of the pheromones and can be used to monitor the association of the pheromones with the lipid bilayer.

Amino Acid Sequence↗
PubMed1995

Use of the Perceived Physical Competence Scale with adolescents with disabilities.

The construct validity and reliability of the 1987 Perceived Physical Competence Scale of Lintunen were examined to assess the applicability of the instrument for use with adolescents with disabilities. Subjects were 51 girls and 34 boys (M age = 15.1 yr.) from several schools in central Finland. Principal component factor analysis with varimax rotation yielded the same two factors for adolescents with disabilities as reported for nondisabled adolescents in the related literature. Cronbach alphas for the two factors were .89 and .56. It was concluded that the scale is an appropriate measure for adolescents with disabilities. Statistical analysis indicated no gender differences for adolescents with disabilities. When compared with nondisabled groups in the related literature, these adolescents had perceived fitness similar to non-disabled peers but significantly lower than that of athletes without disabilities.

Adolescent↗
PubMed1992

Use of a sport socialization inventory with cerebral palsied youth.

The validity and reliability of the 1978 Sport Interest Inventory of Greendorfer and Lewko were examined to evaluate its appropriateness for youth with cerebral palsy, ages 13 to 21 years. Test-retest data from 35 subjects indicated a reliability coefficient of .92. Data from 112 subjects were subjected to factor analysis to examine construct validity. This analysis indicated that the factor structure was similar to that reported for able-bodied youth, except for the items pertaining to friends and opportunity set.

Adolescent↗
PubMed1990

Self-actualisation of elite wheelchair athletes.

The purpose of this study was to examine the self-actualisation of male and female elite wheelchair athletes in comparison to the general population and to able-bodied athletes. All subjects completed the Personal Orientation Inventory (POI), and statistically significant differences were identified. In general, wheelchair athletes were similar to the general population. Male wheelchair athletes were significantly more self-actualised than able-bodied athletes, but female wheelchair athletes were self-actualised to the same extent as able-bodied athletes.

Adaptation, Psychological↗
PubMed1990

Self-concepts of disabled youth athletes.

A self-concept inventory was administered to 158 youth athletes, ages 9 to 18 yr. (M = 13.94 yr., SD = 2.63) who competed in the first Pan American Victory Games for Physically Disabled Youth. Disabilities represented were blind (n = 57), cerebral palsy (n = 52), dwarfs (n = 18), spinal cord injured (n = 12), amputation (n = 10), and les autres (n = 9). The purpose was to examine the self-concepts of disabled youth athletes and begin a data base. Analysis indicated that mean self-concept scores fell within or were close to ranges of means for able-bodied youth, as given in the test manual.

Adaptation, Psychological↗
PubMed1990

Use of a pictorial scale of perceived competence and acceptance with learning disabled boys.

The purpose of this study was to examine the psychometric properties of the Pictorial Scale of Perceived Competence and Acceptance for use with young handicapped children (M age = 8.2 yr.) with severe reading problems. Subjects were 30 learning disabled boys from four private schools located in the Dallas/Ft. Worth metroplex. Data were collected through test-retest administration of the scale and individual interviews with each child. Validity of the physical subscale was established by showing that subjects' reasons for their feelings of physical competence could be classified into one of five categories 89.2% of the time. For the four subscales, alpha coefficients ranged from .56 to .82, and test-retest reliability ranged from .76 to .92.

Achievement↗
PubMed1990

Self-concepts of Costa Rican elementary school children.

The Martinek-Zaichkowsky Self-concept Scale was administered to 797 Costa Rican children in Grades 1 to 6. A three-way analysis of variance and Scheffé tests, used in conjunction with a 7 x 6 x 2 factorial design, showed significant differences between school types based on enrollment, grades, and sex. The highest self-concepts were found in the first grade and girls. Children in schools with enrollments under 50 scored significantly lower than those in larger schools. Findings were discussed in relation to literature for children in the USA.

Child↗
PubMed1990

Comparison of wheelchair athletes and nonathletes on selected mood states.

The Profile of Mood States was administered to two groups of male university students in wheelchairs. Both the 26 wheelchair athletes and the 28 wheelchair nonathletes exhibited the iceberg profile associated with positive mental health. Multivariate analysis indicated that wheelchair athletes had a significantly lower score on Depression than the wheelchair nonathletes but all scores were in the normal range.

Adaptation, Psychological↗
PubMed1990

Motor development of Puerto Rican children: cross-cultural perspectives.

The Test of Gross Motor Development was administered to 300 children, ages 5 to 7 yr., attending public schools in Puerto Rico. Statistical comparisons indicated that the test-manual norms for US children were applicable to Puerto Rican children except for 7-yr.-old girls. A 2 x 3 x 2 factor analysis of intercorrelations of Puerto Rican scores indicated no significant difference between rural and urban children, expected age group differences, and sex differences favoring boys.

Child↗
PubMed1989

Use of a motor creativity test with young learning disabled boys.

The Torrance Test of Thinking Creatively in Action and Movement, developed to measure the motor creativity of children ages 3 to 8 yr., has been subjected to little psychometric study. The purpose of this study was to examine the feasibility of using this instrument with young learning disabled boys and to determine whether differences between learning disabled boys and the test manual's nondisabled normative sample (n = 193) were significant. Subjects were 30 learning disabled boys (M = 8.11 yr.), representing seven different school systems. Significant differences were noted between two groups on fluency, imagination, and total motor creativity but not on originality. Test-retesting over 1 to 14 days gave coefficients of .71 to .89. The alpha coefficient for total test internal consistency was .79.

Child↗
PubMed1989

Attitude toward physical education and self-concepts of asthmatic and nonasthmatic children taught by physical education specialists.

50 asthmatic and 741 nonasthmatic children in Grades 4 to 6 were compared on attitudes toward physical education and self-concept. Data were collected using the Children's Attitude Inventory Toward Physical Education, a paired-comparison inventory for indicating preferences among 10 school subjects, and the Children's Self-concept Scale. Analysis of variance and X2 indicated no significant differences between asthmatic and nonasthmatic children on the three measures.

Adolescent↗
PubMed1989

Attitudes toward handicapped peers of mainstreamed and nonmainstreamed children in physical education.

The influence of contact (mainstreamed and nonmainstreamed) and sex on attitudes of fifth- and sixth-grade students toward handicapped children was examined. 143 mainstreamed students attended an integrated school, whereas 86 nonmainstreamed students had no handicapped children in their school. Mean responses to the Children's Attitudes Toward Handicapped Scale were subjected to a 2 x 2 analysis of variance which indicated no significant differences by contact or sex. Chi 2 analysis of individual items indicated some significant differences, favoring contact, on items "are fun" and "are interesting".

Attitude↗
PubMed1989

Fitness, attitude toward physical education, and self-concept of elementary school children.

Elementary school children scoring in the highest and lowest 26% or 27% of their classes on the Texas Physical Fitness test were compared for attitude toward physical education and self-concept. Data were collected on the Children's Attitude Inventory Toward Physical Education, a Game of Pairs for Preferences Among School Subjects, and the Children's Self-concept Scale. Analysis of variance indicated significant differences on all tests between boys high in fitness, girls high in fitness, boys low in fitness, and girls low in fitness. Subsequent Scheffé tests indicated that highly fit girls had significantly higher attitude and self-concept scores than boys low in fitness. Highly fit boys had higher self-concepts than boys low in fitness. No other group comparisons were significant. Pearson correlations indicated nonsignificant associations between fitness and attitude and self-concept for the four groups.

Attitude↗
PubMed1988

Use of the personal orientation inventory with disabled athletes.

Athletes who are blind or have impairments in hand-eye coordination that prevent writing are unable to complete psychological inventories in the standardized manner, i.e., read silently and answered independently and anonymously. Two studies were conducted on the oral administration of the Personal Orientation Inventory as a measure of self-actualization of disabled athletes. Reliabilities were examined across modalities (oral vs written) by administering the inventory both ways to 25 high school and college athletes, M age = 21.6 yr. Test-retest reliability for oral administration was affirmed in a study of 15 blind elite male athletes and 15 cerebral palsied elite male and female athletes. It was concluded that the inventory, administered orally, may be appropriately used with disabled athletes.

Adolescent↗