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Biomedical subjects

C Lloyd

Publications and source records attributed to C Lloyd.

11 recordsLinked to original sources
PubMed1992

High level expression of transfected beta- and gamma-actin genes differentially impacts on myoblast cytoarchitecture.

The impact of the human beta- and gamma-actin genes on myoblast cytoarchitecture was examined by their stable transfection into mouse C2 myoblasts. Transfectant C2 clones expressing high levels of human beta-actin displayed increases in cell surface area. In contrast, C2 clones with high levels of human gamma-actin expression showed decreases in cell surface area. The changes in cell morphology were accompanied by changes in actin stress-fiber organization. The beta-actin transfectants displayed well-defined filamentous organization of actin; whereas the gamma-actin transfectants displayed a more diffuse organization of the actin cables. The role of the beta-actin protein in generating the enlarged cell phenotype was examined by transfecting a mutant form of the human beta-actin gene. Transfectant cells were shown to incorporate the aberrant actin protein into stress-fiber-like structures. High level expression of the mutant beta-actin produced decreases in cell surface area and disruption of the actin microfilament network similar to that seen with transfection of the gamma-actin gene. In contrast, transfection of another mutant form of the beta-actin gene which encodes an unstable protein had no impact on cell morphology or cytoarchitecture. These results strongly suggest that it is the nature of the encoded protein that determines the morphological response of the cell. We conclude that the relative gene expression of beta- and gamma-actin is of relevance to the control of myoblast cytoarchitecture. In particular, we conclude that the beta- and gamma-actin genes encode functionally distinct cytoarchitectural information.

Actin Cytoskeleton↗
PubMed1992

Transfection of nonmuscle beta- and gamma-actin genes into myoblasts elicits different feedback regulatory responses from endogenous actin genes.

We have examined the role of feedback-regulation in the expression of the nonmuscle actin genes. C2 mouse myoblasts were transfected with the human beta- and gamma-actin genes. In gamma-actin transfectants we found that the total actin mRNA and protein pools remained unchanged. Increasing levels of human gamma-actin expression resulted in a progressive down-regulation of mouse beta- and gamma-actin mRNAs. Transfection of the beta-actin gene resulted in an increase in the total actin mRNA and protein pools and induced an increase in the levels of mouse beta-actin mRNA. In contrast, transfection of a beta-actin gene carrying a single-point mutation (beta sm) produced a feedback-regulatory response similar to that of the gamma-actin gene. Expression of a beta-actin gene encoding an unstable actin protein had no impact on the endogenous mouse actin genes. This suggests that the nature of the encoded actin protein determines the feedback-regulatory response of the mouse genes. The role of the actin cytoskeleton in mediating this feedback-regulation was evaluated by disruption of the actin network with Cytochalasin D. We found that treatment with Cytochalasin D abolished the down-regulation of mouse gamma-actin in both the gamma- and beta sm-actin transfectants. In contrast, a similar level of increase was observed for the mouse beta-actin mRNA in both control and transfected cells. These experiments suggest that the down-regulation of mouse gamma-actin mRNA is dependent on the organization of the actin cytoskeleton. In addition, the mechanism responsible for the down-regulation of beta-actin may be distinct from that governing gamma-actin. We conclude that actin feedback-regulation provides a biochemical assay for differences between the two nonmuscle actin genes.

Actin Cytoskeleton↗
PubMed1992

Staff anxieties about death in residential settings for elderly people.

This study examined the relationship between death anxiety, the anxiety surrounding dealing practically with dying, and the level of experience of care assistants in residential settings for the elderly. It also examined the perception of the officer in charge of the establishment of the care assistants' level of anxiety. Age was the best predictor of both death anxiety and practical anxiety, the two being correlated. There was also a difference in perception of staff anxiety as a consequence of ethnic-group membership. The implications of this for training and practice are discussed.

Adult↗
PubMed1992

Personality, self-esteem, stress, and satisfaction among Texas dentists.

Do the personality styles of dentists significantly influence their sense of well-being in their profession? A recent study using the Bi/Polar Inventory of Core Strengths differentiated 218 Texas dentists into eight personality profiles. Patterns VII and V (both risking and practical) as a group reported significantly higher self-esteem, higher ability to cope with stress, lower psychological distress, higher satisfaction with dentistry, and greater likelihood of choosing dentistry again as a career, than did Patterns III and IV (both thinking and theoretical). The results suggest that Patterns VII and V may be the most compatible with dentistry, and Patterns III and IV the least compatible. Also, the practical orientation (preferred by nearly 80% of the Texas dentists sample over the theoretical orientation) may be the single most influential personality trait in terms of compatibility with dentistry. Implications arise in career counseling, dental school admissions committees, and counseling dentists dissatisfied with.

Dentists↗
PubMed1992

Personality patterns of Texas dentists: a study using the bi/polar theory.

Are individuals with certain personality styles uniquely attracted to dentistry? A recent study with 218 Texas dentists using the Bi/Polar Inventory of Core Strengths showed that the dentists were more thinking (57.3%) than risking, profoundly more practical (78.0%) than theoretical, and more independent (67.9%) than dependent. Compared with the general population, dentists were significantly more thinking, practical and independent. Of the eight personality styles, Pattern II (thinking-practical-independent) (29.4%) was the only pattern significantly over-represented among the dentists compared with the general population. However, Pattern I (thinking-practical-dependent) (17.4%) was also over-represented at the trend level. Significantly under-represented among the dentists were Pattern V (risking-practical-dependent) (6.9%) and Pattern VI (risking-theoretical-dependent) (3.2%). Results suggest at least some personality influence on attraction to dentistry.

Aptitude↗
PubMed1991

Social support and its interactions with personality and childhood background as predictors of psychiatric symptoms in Scottish and American medical students.

Two samples of first year medical students were studied, one in Houston, Texas, the other in Edinburgh, Scotland. Personality, measured on entry, and social support, measured prior to first year examinations, were used to predict scores at the latter time on anxiety self-ratings, depression self-ratings and the General Health Questionnaire. At both centres social support was implicated in symptomatology, but many significant effects were centre specific. Presence of a local friend in whom to confide, was important in Houston, while support from a relative and superficial support from classmates were salient in Edinburgh. In general, presence of support was associated with lower symptoms, but there were important exceptions similar in both centres. Students who did not have a boy/girl friend during the study period were less anxious than the rest. Regarding personality, students high on suspiciousness were more anxious and depressed when they had high levels of support. Among reserved (aloof and introspective) students both gain and loss of a boy/girl friend during the year were strongly associated with depressed mood. It is concluded that, particularly for students high in suspiciousness, reserve and shyness, the costs of social relationships sometimes outweigh the benefits.

Adult↗
PubMed1990

Immunological studies before and during interferon therapy in chronic HBV infection: identification of factors predicting response.

Lymphoblastoid interferon is effective therapy in some but not all patients with chronic hepatitis B virus infection. To assess whether immunological parameters were predictive of response to interferon therapy, we determined the human leukocyte antigen type, CD4/CD8 ratio, natural killer cell activity, IgM anti-HBc antibody levels and concanavalin A-induced lymphocyte proliferative response in 30 patients before treatment. In addition, to investigate the mechanisms of action of interferon in promoting hepatitis B virus clearance, we serially measured the CD4/CD8 ratios, natural killer activity and lymphocyte proliferative response at wk 4, 8 and 12 of treatment. A beneficial response to therapy was defined as the sustained clearance of HBeAg and serum hepatitis B virus DNA within 1 yr of commencing therapy. Elevated IgM anti-HBc levels were associated with a beneficial response to therapy, but there was no correlation observed between response and pretreatment CD4/CD8 ratio, natural killer activity or lymphocyte proliferative response. Six of seven human leukocyte antigen DR3-positive patients responded. No measurable changes in the immunological parameters studied were observed in the nonresponder group, whereas a significant rise in CD4/CD8 ratio, associated with a fall in peripheral CD8 number and a decline in measurable NK activity, was seen in the responder group. These changes were maximal at the time of hepatitis B virus DNA clearance, which was associated with a transient increase in hepatic inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1979

Poles apart?

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Carbamates↗