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Biomedical subjects

C Lloyd

Publications and source records attributed to C Lloyd.

At least 73 records · Page 4Linked 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↗
PubMed1990

The influence of the interdigestive migrating myoelectric complex on the gastric emptying of liquids.

It is unknown how the interdigestive migrating motor complex influences the gastric emptying of liquids. Therefore, the gastric emptying rate of 50- and 200-mL volumes of phenol red solution were measured while monitoring contractile activity. Motor activity was recorded using a hydraulic manometric system and expressed as either the proximity of dosing time to time of appearance of phase III or as a motility index, defined as (contractile area)/(sampling interval time). After an initial lag period, emptying was log linear. With a 50-mL oral dose, the mean gastric emptying rate of the log-linear phase was successively faster during phase I (0.018 +/- 0.003 min-1), phase II (0.083 +/- 0.031 min-1), and late phase II/III (0.171 +/- 0.066 min-1) (P less than 0.05). Similarly, the mean lag time decreased successively with phases I, II, and late II/III (19.1 +/- 12.4, 7.6 +/- 5.6, and 3.8 +/- 2.8 minutes, respectively). At a 200-mL oral dose, there was no difference in the emptying rate between phase I and phase II (0.104 +/- 0.0014 vs. 0.110 +/- 0.041 min-1), but the emptying rate during late phase II/III was significantly greater (0.236 +/- 0.069 min-1); lag time was not dependent on phase. There was a statistical difference in the overall mean emptying rate between the 50- and 200-mL volumes. Also, during phase I, the emptying rate was faster for the 200-mL volume. This study shows a strong dependence of liquid gastric emptying rate and lag time on interdigestive antral motility, the emptying of small volumes being more dependent on motility phase than that of large volumes. Phase-related fluctuations in contractile activity can account for much of the reported variability in gastric emptying data. Furthermore, this study suggests that dose volume and interdigestive motor activity at the time of drug administration can affect absorption and onset of therapeutic response for some drugs.

Analysis of Variance↗
PubMed1990

The relationship of Bi/Polar personality patterns with self-esteem, stress, and satisfaction in dental school.

The Bi/Polar Inventory of Core Strength was administered to two senior dental classes. This inventory identifies preferences on three fundamental underlying dimensions of personality and yields eight personality patterns, which were subsequently correlated with the students' self-assessment of various aspects of the dental school experience. Individuals with preferences for risking, practical thinking, and independence consistently demonstrated higher self-esteem, higher ability to cope with the stresses of dental school, lower psychological distress in dental school, and higher satisfaction with dentistry than individuals with polar opposite preferences--thinking, theoretical thinking, and dependence--although only some of these comparisons reached statistical significance. Pattern III (thinking-theoretical-dependent) reported the lowest self-esteem, lowest ability to cope with stress, highest psychological distress, and lowest satisfaction with dentistry. Pattern III may represent a psychological profile exhibiting early warning signs of a potential tension with the task demands of clinical dentistry. Conversely, Pattern VII (risking-practical-independent) may represent a profile prone to high self-esteem, high-stress resistance, low psychological distress, and reasonably high satisfaction with dentistry.

Adult↗
PubMed1989

Psychiatric symptoms in dental students.

Prior research has suggested that dentistry is a relatively stressful occupation that may place its practitioners at an increased mental health risk. Whether or not this susceptibility to mental distress is also evident in those who are being educated to enter the occupation has not been previously studied. The purpose of the present study was to examine the presence of psychiatric symptomatology in a sample of dental students by using the Hopkins Symptom Checklist. Results indicate that dental students evidenced considerably higher symptom levels than those previously reported in a general population survey. Compared with the general population, dental students showed a mild elevation in somatic symptomatology, a moderate elevation in anxiety and depressive symptomatology, and a marked elevation in obsessive-compulsive symptomatology and interpersonal sensitivity. It is possible that the marked elevations in obsessive-compulsive symptomatology and in interpersonal sensitivity may reflect in part a sensitization to excessive performance demands. This sensitization may manifest itself in cognitive inefficiencies such as indecisiveness, blocking or memory impairment, and excess sensitivity to the evaluative judgments of other people. In comparing dental students with other sample groups, dental students were also found to evidence more psychiatric symptomatology than general medical patients judged free of psychiatric illness, and to approach levels of symptomatology found in general medical patients judged psychiatrically ill or in need of psychiatric treatment.

Adult↗
PubMed1989

Evidence for a menstrual-linked artifact in determining rates of depression.

This is the first empirical report suggesting a menstrual-linked artifact in determining rates of depression. We investigated the effects of perceived menstrual cycle phase, and premenstrual and postmenstrual timing in the cycle, on scores for a self-report measure of depression that is widely used in epidemiological studies, the Center for Epidemiologic Studies Depression Scale (CES-D). The first study used a cross-sectional design and the second used a follow-up design with repeated measures across the menstrual cycle. Both studies assessed a community-based sample of regularly menstruating women. In the second study, testing was also done at 2-week intervals in men for comparison purposes. Both studies supported the hypothesis of a significant menstrual cycle-related effect on CES-D scores. The menstrual-linked effect is greater than the test-retest variability observed in men, such that women more often tend to meet the cut-off criteria for depression on the CES-D premenstrually, as compared with postmenstrually. Thus it is possible that cyclic variations in ratings on the CES-D may elevate epidemiological estimates of depression, as defined by RDC criteria, for menstruating women. Further longitudinal assessment in randomly selected samples will be needed in order to clarify whether a menstrual-linked effect is substantial and specific enough to require correction, or documentation of cycle phase, in epidemiological studies of depression.

Adult↗
PubMed1989

Deconjugation of p-hydroxytriamterene sulphate in the rat.

1. The extent of deconjugation of p-hydroxytriamterene sulphate was studied in rats, by h.p.l.c., after i.v., i.p., and oral administration. 2. After i.v. administration, deconjugation accounted for 29-54% of the recovered dose as free p-hydroxytriamterene in urine and faeces. Following i.p. administration, 70-88% was deconjugated and 72-96% was deconjugated after oral administration. Most of the p-hydroxytriamterene was recovered in faeces.

Administration, Oral↗
PubMed1989

Rapid screening for deficiency of alpha 1-proteinase inhibitor.

This rapid screening procedure for detection of low but functional elastase-inhibitory activity in human plasma is based on the fact that incubation of excess porcine pancreatic elastase (EC 3.4.21.36) with plasma results in formation of a complex with active alpha 1-proteinase inhibitor (alpha 1PI, also called alpha 1-antitrypsin). In normal individuals all of the elastase is complexed, leaving no free enzyme to hydrolyze the elastase substrate, and the reaction mixture remains clear. Because individuals homozygous for the Z allele have relatively low concentrations of alpha 1PI, their plasma cannot complex all of the elastase in the assay. The uncomplexed enzyme hydrolyzes the elastase-specific p-nitroanilide substrate, producing a yellow reaction mixture. Use of this simple assay for early screening of individuals for alpha 1PI deficiency may substantially decrease the number of untreated cases of familial emphysema, a disorder that develops as a result of a genetically derived proteinase-proteinase inhibitor imbalance.

Alpha-Globulins↗
PubMed1988

Structure and differential mechanisms of regulation of expression of a serine esterase gene in activated human T lymphocytes.

A cDNA clone encoding a polypeptide resembling proteolytic serine esterases (from cytotoxic T-cells; SECT) was isolated from human peripheral blood lymphocytes which had been cultured in the presence of the T-cell mitogen phytohemagglutinin for 72 h. The cDNA encodes a polypeptide of 247 amino acids which show homology of 99% with the protein sequence encoded by a cDNA clone (1-3E) isolated from staphylococcal enterotoxin A-stimulated human peripheral blood lymphocytes and 68% with the protein sequence (cytotoxic cell protease type I) derived from a cDNA clone (C11) encoding a serine esterase isolated from a murine cytotoxic T-cell line. The overall nucleotide sequence homology between the SECT cDNA and 1-3E was 99% and 73% between SECT and C11. Comparing the coding regions of SECT and C11 showed 75% homology, whereas the 5'- and 3'-untranslated regions showed 67% homology. Phytohemagglutinin stimulation results in 30-, 60-, and 370-fold increases in cytoplasmic SECT mRNA with respect to unstimulated cells after 6-, 24-, and 72-h cultures, respectively. At 6 h, the increase in SECT mRNA occurs in the absence of increases in SECT gene transcription and cytoplasmic mRNA stabilization. A 5-fold increase in SECT nuclear RNA seen at this time suggests that stabilization of SECT nuclear RNA transcript is responsible for early increases in SECT mRNA levels. At 24 and 72 h, the increased cytoplasmic SECT mRNA levels can be accounted for by increased transcriptional activity of the SECT gene.

Amino Acid Sequence↗
PubMed1988

Bi/Polar personality patterns of senior dental students.

The Bi/Polar Inventory of Core Strengths was administered to two senior dental classes. Students preferred thinking (58.3 percent) over risking (41.7 percent), practical thinking (78.7 percent) over theoretical thinking (21.3 percent), and independent risking (59.1 percent) over dependent risking (40.9 percent). Compared to the general population, dental students were more thinking and practical, but nearly identical in independence-dependence. Pattern II (thinking-practical-independent) was the most common student pattern (25.2 percent) and Pattern VI (risking-theoretical-dependent) was the least common (3.9 percent). Results suggest a dominance of certain personality styles in dental students.

Adult↗
PubMed1987

Expression in COS cells of a mouse-human chimaeric B72.3 antibody.

B72.3 is a mouse hybridoma cell-line secreting an IgG1 antibody which recognises an epitope on a tumour-associated antigen, TAG-72. This high molecular weight mucin-like molecule is found on a variety of human neoplasms, including colon, breast and ovarian carcinomas. Chimaeric immunoglobulin genes with the B72.3 specificity have been constructed by joining the mouse variable regions from cDNA clones to human genomic constant regions using recombinant DNA techniques. The chimaeric heavy and light chain immunoglobulin genes were placed under the control of a strong viral promoter, and co-transfected into COS-1 cells. SDS-PAGE analysis of the 35S-labelled products demonstrated that the transiently expressed antibodies were correctly synthesised and assembled. The specific binding characteristics of the parent B72.3 antibody were retained by the chimaeric antibody in an antigen-based ELISA. This system gave sufficiently high transient expression of the chimaeric antibody molecules to allow rapid physical and immunological characterisation of the engineered gene products.

Amino Acid Sequence↗
PubMed1986

The relationship between social support and psychiatric symptomatology in medical students.

This study investigated the relationship between social support and psychiatric symptom-atology among 82 first-year medical students at the University of Texas Medical School at Houston. A questionnaire was administered at several points during the medical school year. This questionnaire included the Hopkins Symptom Checklist and a measure of social support adapted for this study. It was hypothesized that social support and psychiatric symptomatology would be negatively correlated, i.e., that students who described themselves as experiencing more social support would be less symptomatic. The data supported this hypothesis at the beginning of the school year. However, by midyear, social support and symptomatology were positively correlated with each other. These findings, in conjunction with a few isolated studies in the social support literature, led the authors to conclude that in certain settings such as medical school, social ties may present competing demands on an individual's time and energy which have potentially detrimental as well as beneficial effects on mental health. In addition, the findings suggested that the relationship of social support to psychiatric symptomatology may change over time, that there are gender differences in the relationship, and that there may be an interaction between demographic factors, such as gender and marital status, and social support.

Female↗