Biomedical subjects

M C Rush

Publications and source records attributed to M C Rush.

8 recordsLinked to original sources

PubMed2004

Characterization of antimicrobial peptides against a US strain of the rice pathogen Rhizoctonia solani.

AIM: To identify antimicrobial peptides with high lytic activity against Rhizoctonia solani strain LR172, causal agent of rice sheath blight and aerial blight of soyabeans in the US. METHODS AND RESULTS: Among 12 natural and synthetic antimicrobial peptides tested in vitro, the wheat-seed peptide, purothionin, showed the strongest inhibitory activity that was similar to the antifungal antibiotics, nystatin and nikkomycin Z. Cecropin B, a natural peptide from cecropia moth, and synthetic peptide D4E1 produced the highest inhibitory activity against R. solani among linear peptides. Membrane permeabilization levels strongly correlated with antifungal activity of the peptides. Noticeable changes in membrane integrity were observed at concentrations of >/=0.5 micromol l(-1) for purothionin, 2 micromol l(-1) for cecropin B, D4E1, D2A21, melittin, and phor21, and 8 micromol l(-1) for magainin II and phor14. An increase of nuclear membrane permeabilization was observed in fungal cells treated with cecropin B, but not with purothionin. Diffusion of nuclear content was observed by fluorescent microscopy 10 min after adding a lethal concentration of cecropin B. Evaluation by electron microscopy confirmed severe cytoplasmic degradation and plasma membrane vesiculation. Purothionin and cecropin B were the most stable against proteolytic degradation when added to liquid cultures of R. solani. CONCLUSIONS: Purothionin, cecropin B, D4E1 and phor21 were shown to exhibit high in vitro lytic activity against R. solani strain LR172 for rice and soyabean. These peptides are greater than 16 amino acids long and rapidly increase fungal membrane permeabilization. Resistance to proteolysis is important for sufficient antifungal activity of antimicrobial peptides. SIGNIFICANCE AND IMPACT OF THE STUDY: Selected antimicrobial peptides offer an attractive alternative to traditional chemicals that could be utilized in molecular breeding to develop crops resistant to rice sheath blight and aerial blight of soyabean.

Antimicrobial Cationic Peptides↗

PubMed2000

Altruistic organizational citizenship behavior: context, disposition, and age.

The authors proposed employee age as moderating the structural stability of altruistic organizational citizenship behavior (OCB) with regard to the influence of context-relevant attitudes and dispositional variables. Analyses of peer ratings of altruistic OCB in a sample of 96 U.S. nurses showed that the contextual variables of job satisfaction, organizational commitment, and trust in management were germane for the younger participants. The dispositional variable of moral judgment was a unique predictor of altruistic OCB among the older participants.

Adult↗

PubMed1998

The effects of organizational citizenship behavior on performance judgments: a field study and a laboratory experiment.

The process linking organizational citizenship behavior (OCB) with performance judgments was investigated in a field and a laboratory study. In the field study, managers rated the task performance and OCB of 148 subordinates. In the laboratory research, 136 students viewed and rated videotaped segments of teaching performance that demonstrated either high or low task performance and high or low OCB. In both studies, liking and perceived affective commitment mediated the relationship between OCB and overall evaluation. Liking also mediated the relationship between OCB and reward recommendations. Further, the field study indicated that the causal motive attributed by the manager for the employee's OCB mediated the relationship between OCB and overall evaluation.

Adult↗

PubMed1990

Analysis of individual variability among older adults on the Stroop Color Word Interference Test.

The present study examines systematic variation in the pattern of response to the Stroop test among a sample of older adults (N = 41), as well as the extent to which various configural patterns of response are related to other individual difference factors. Pattern analysis identified four reasonably prototypic patterns of performance. Three significant discriminant functions, capable of differentiating the four response patterns, were significantly and uniquely related to age, level of cautiousness, and verbal intelligence, respectively. The analyses suggest that performance on the Stroop test is multidimensional with significant variation among older adults, and that different components of performance are differentially related to unique individual difference variables. The findings reinforce the importance of recognizing and understanding the nature of individual variation among elderly individuals in aging research.

Age Factors↗

PubMed1987

Cautiousness and visual selective attention performance among older adults.

Cautiousness has been implicated in the literature as a possible factor responsible for observed performance decrements among older adults in a number of research paradigms. This study sought to assess whether the speed and accuracy of performance on a perceptual-cognitive task (the Stroop Color-Word Interference Test) differed significantly for more and less cautious older adults. The participants (N = 41), ranging from 55 to 81 years of age, were classified as either more cautious (n = 20) or less cautious (n = 21) on the basis of their responses on a personality test. Results indicated that cautiousness among older adults was manifested more in terms of the accuracy of response (fewer errors of commission) than in terms of the speed of response, and that level of cautiousness increased with increasing age.

Aged↗

PubMed1985

Response pattern analysis of the Hand Test: age differences.

Extended the literature on age differences on the Hand Test using a multivariate model to examine absolute and relative differences in response. Participants were 47 adults (M age = 22.47 yrs.), 24 males and 23 females; and 45 older adults (M age = 64.87 yrs.), 21 males and 24 females. Data were analyzed in terms of percentage of response and absolute frequency of specific responses, between the age groups. Results indicated similar findings to those previously reported for the Hand Test, though magnitude of personality deterioration or withdrawal was lessened, for the percentage analysis. Results indicated the importance of using both absolute frequency of response and percentage of response in the interpretation of projective test data, especially for older adults.

Adult↗

PubMed1981

Simultaneous examination of age related differences in the ability to maintain and reorient auditory selective attention.

The present investigation simultaneously examined age-related differences in the ability to maintain and reorient auditory selective attention. The maintenance and reorientation components of attention were assessed by means of an auditory listening task involving 24 dichotic trails. The trails were counter-balanced for right-ear and left-ear relevance, with each trail involving two parts. The first part required maintenance of attention and second part required a reorientation of attention. The participants for the study were 90 community-living women recruited to represent an age continuum of young adult, adult, and older adult. It was hypothesized that there would be a significant decrement in both maintenance and reorientation of attention with increasing age, and that reorientation of attention would be more difficult than maintenance of attention, particularly for older adults. The results of multivariate and univariate analyses confirmed the hypotheses and suggested that an inability to reorient attention, coupled with a tendency for right-ear set, was primarily responsible for the manifest differences in selective attention ability of older adults. The results are discussed in terms of theoretical implications and the relationship of the findings with previous research.

Adult↗

PubMed1979

Intellectual and personality differences between community-living and institutionalized older adult females.

The purpose of the present study was to investigate simultaneously differences between normal institutionalized older adults and community-living older adults with respect to intelligence/cognitive test performance and personality. Participants were 25 community-living females (M age = 72.9 yrs, SD = 6.34) and 25 institutionalized females (M age = 80.0 yrs, SD = 6.46). Intellectual/cognitive ability was assessed by the WAIS, Stanford-Binet Intelligence Scale (Form L-M), Ravens Coloured Progressive Matrices; personality was assessed by the Hand Test, a projective technique. Several multivariate analyses (discriminant analysis) were conducted. Results suggested that even when controlling for age and level of education, institutionalization appears to be associated with intellectual/cognitive as well as personality deficits. The findings were discussed in terms of the potential implications for the professional working with institutionalized older adults.

Aged↗