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Biomedical subjects

C Lee

Publications and source records attributed to C Lee.

At least 829 records · Page 46Linked to original sources
PubMed1989

Perceptions of immunity to disease in adult smokers.

Public education has ensured smokers' awareness of the health risks of smoking. It has been suggested that engaging in a behavior (e.g., smoking) which one knows to be dangerous will result in an unpleasant state of "cognitive dissonance." Smokers may deal with such a state by denying the dangers of smoking. In this study, 97 smokers and 95 nonsmokers (age range, 15-65 years) rated the risk to themselves and to the average Australian smoker of contracting three smoking-related diseases. Evidence supportive of denial of risk was found: smokers' ratings of the risk to the average smoker were lower than nonsmokers' ratings, and smokers' ratings of their own risk were lower still. Such denial of risk may undermine the effectiveness of stop-smoking campaigns which focus on health aspects of smoking, and methods of dealing with this problem are discussed.

Adolescent↗
PubMed1989

Theoretical weaknesses lead to practical problems: the example of self-efficacy theory.

Bandura's self-efficacy concept has received widespread acceptance from psychologists dealing with a varied range of behaviors. This paper argues that, like many related models, its ability to explain human behavior is largely illusory. It has its basis in the argument that behavior arises from complex interactions between unobservable variables which are vaguely defined and cannot be assessed. For example, the process by which efficacy expectations arise from various sources of information, and the interaction of self-efficacy with levels of skill and motivation, are argued to be important, but there is no model to explain how these processes occur. Since unambiguous predictions cannot be made, it is impossible to test the model in a scientific sense. This weakness seriously compromises the practical usefulness of the theory.

Behavior Therapy↗
PubMed1989

Smoking cessation by mail: a comparison of standard and personalized correspondence course formats.

Self-Instructional behavior-change programs for reducing risks to health are potentially widely available, acceptable and cost-effective. This paper reports outcomes of a smoking cessation program administered by mail. Two hundred and eight smokers were allocated systematically to a quit kit control condition (n = 40), to a standard correspondence course (n = 86) and to a personalized correspondence course prepared with the aid of a microcomputer (n = 82). There were significantly higher rates of abstinence after the course for correspondence course participants compared to controls, but these differences did not persist at three-month and nine-month follow-ups. There were no differences between the personalized and standard courses on abstinence rates, number of cigarettes smoked per day, or return of feedback forms on each lesson. There were associations between self-efficacy strength and reduced rates of smoking, and active participation in the course was associated with lower smoking rates.

Behavior Therapy↗
PubMed1989

Stereotypes of smokers among health science students.

Despite the serious and well-known health risks associated with cigarette smoking, smoking rates continue to be high, particularly in young women. Positive images of smokers presented by cigarette advertisers appear to affect public opinions of smoking. This paper describes two investigations of the image of smoking held by health science students. Subjects were given a brief description of a fellow student and asked for their first impressions. For some students, the descriptions included the information that the student smoked, while in other conditions this information was deleted. Study One showed that nursing students held a clear and mainly positive stereotype of the young female smoker, regardless of whether or not they smoked themselves. Study Two replicated this finding with a group of physiotherapy students, and extended it to include male smokers. The results are discussed in terms of their implications for community interventions; in particular, it is suggested that the existence of a positive stereotype of the smoker among health professionals could seriously undermine such interventions.

Adult↗
PubMed1989

Intravesical mitomycin C instillation as a prophylactic treatment of superficial bladder tumor.

A study was performed to determine the prophylactic efficacy of intravesical mitomycin C instillation in 43 patients with recurrent (more than 3), multiple (more than 3) or large (more than 3 cm.) superficial bladder tumors (stage Ta or T1). Of the patients 21 were treated with 8 weekly intravesical instillations of 40 mg. mitomycin C after transurethral resection and 22 were followed conventionally. The recurrence rate was 42.9 per cent in the mitomycin C group and 40.9 per cent in the controls during the first 3 months, and it was 81.0 and 77.3 per cent, respectively during 24 months. Recurrences per 100 patient-months were 8.7 and 8.9, respectively. Two patients in the mitomycin C group and 4 controls had recurrent tumors with progression in stage. We conclude tentatively from these observations that intravesical mitomycin C instillation is not effective in the prophylaxis of tumor recurrence in patients at high risk. This finding is contrary to other reports indicating a marked decrease in recurrence with mitomycin C.

Administration, Intravesical↗
PubMed1989

Construction of the endoplasmic reticulum.

To study the construction of the ER, we used the microtubule-disrupting drug nocodazole to induce the complete breakdown of ER structure in living cells followed by recovery in drug-free medium, which regenerates the ER network within 15 min. Using the fluorescent dye 3,3'-dihexyloxacarbocyanine iodide to visualize the ER, we have directly observed the network construction process in living cells. In these experiments, the ER network was constructed through an iterative process of extension, branching, and intersection of new ER tubules driven by the ER motility previously described as tubule branching. We have tested the cytoskeletal requirements of this process. We find that newly formed ER tubules are aligned with single microtubules but not actin fibers or vimentin intermediate filaments. Microtubule polymerization preceded the extension of ER tubules and, in experiments with a variety of different drugs, appeared to be a necessary condition for the ER network formation. Furthermore, perturbations of the pattern of microtubule polymerization with microtubule-specific drugs caused exactly correlated perturbations of the pattern of ER construction. Induction of abnormally short, nonintersecting microtubules with 20 microM taxol prevented the ER network formation; ER tubules only extended along the few microtubules contacting the aggregated ER membranes. This requirement for a continuous network of intersecting microtubules indicates that ER network formation takes place through the branching and movement of ER membranes along microtubules. Cytochalasin B had no apparent effect on the construction of the ER network during recovery, despite apparently complete disruption of actin fibers as stained by phalloidin. Blockage of protein synthesis and disorganization of intermediate filaments with cycloheximide pretreatment also failed to perturb ER construction.

Actins↗
PubMed1989

Genetic studies on the inability of beta-galactosidase to be translocated across the Escherichia coli cytoplasmic membrane.

When a signal sequence is attached to beta-galactosidase, the normally cytoplasmic protein is unable to fully traverse the cytoplasmic membrane. We used a genetic approach to study those features of beta-galactosidase responsible for the block in translocation. By using both in vivo and in vitro techniques, fragments of beta-galactosidase were interposed between a signal sequence and alkaline phosphatase. The alkaline phosphatase acts as a sensor for any blocking effects of beta-galactosidase on export. From these studies, we show that multiple regions of beta-galactosidase contribute to its failure to be translocated. These results are most easily interpreted if the folding of beta-galactosidase or of domains of it is responsible for the block in export. In addition, in certain constructs, positively charged amino acids directly following the signal sequence interfered with export.

Alkaline Phosphatase↗
PubMed1989

Permeability of the blood brain barrier for 125I-albumin-bound bilirubin in newborn piglets.

Permeability of the blood brain barrier (BBB) for bilirubin and 125I-albumin was studied in 2-d- and 2-wk-old piglets. 125I-albumin was given by bolus at the beginning of each study. Hyperbilirubinemia was produced by an initial bolus infusion of bilirubin and sustained at a plasma bilirubin:albumin molar ratio of approximately 1.0 by continuous infusion of bilirubin for 3 h. During the study period, arterial pH and blood gas tensions, serum osmolarity, and mean arterial blood pressure were within the physiologic range for age in both groups. Serum albumin and serum total and unbound bilirubin concentrations were higher in the 2-wk-old piglets. Brain bilirubin concentrations and permeability (P.S product) of the BBB for bilirubin were higher in the 2-d-old than in the 2-wk-old piglets, but the values of P.S for albumin were not different between the two groups. In 2-d-old piglets, regional brain bilirubin concentrations and permeability of the BBB were higher in subcortical regions (cerebellum and brainstem) than in the cerebral cortex. Regional brain albumin concentrations and BBB permeability to albumin in 2-d-old piglets were higher only in the cerebellum. In all regions, the bilirubin:albumin molar ratio was higher in the brain tissues than in the blood. In 2-wk-old piglets, the brain concentrations and P.S products for bilirubin were lower and the regional differences were less marked than for 2-d-old animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

Alterations in sympathetic nervous system activity with intraoperative hypothermia during coronary artery bypass surgery.

To determine how intraoperative hypothermia associated with coronary bypass surgery (CABS) alters sympathetic nervous system (SNS) activity, we prospectively studied 21 adult CABS patients and measured preoperative, intraoperative, and postoperative circulating catecholamine concentrations. Because thyroid hormone levels change rapidly following CABS, we also serially measured these hormone levels. The measured plasma concentrations for each of the above variables were corrected for hemodilution during CABS by using serum albumin changes as a reference. It was concluded that important alterations in SNS activity and thyroid hormone homeostasis occur in humans during CABS and deep hypothermia, and that changes in core temperature may contribute to these findings. We speculate that these hormonal changes may influence the response to adrenergic receptor therapy in hypothermic patients and may contribute to arrhythmias during rewarming and the immediate postoperative period.

Acetylcholinesterase↗
PubMed1989

Exogenous surfactant replacement therapy of hyaline membrane disease in premature infants.

We conducted a clinical trial to assess whether surfactant-TA given within the first six hours of life could improve oxygenation and reduce the ventilatory support in premature infants with hyaline membrane disease (HMD) during the first 24 hours of life. Eight premature infants with severe HMD requiring ventilation were treated, at a mean age of 2.72 hours, with a single intratracheal instillation of surfactant-TA (120 mg/kg). Arterial oxygenation improved dramatically as reflected by the increase of the a/A PO2 ratio and PaO2 to about 2 times the pretreatment values within 3 hours after surfactant treatment. And thus, oxygen concentrations (FiO2) could be reduced and remained significantly lower than pretreatment values during the first 24 hours after treatment. Infants given surfactant-TA required lower mean airway pressure (MAP) and had a significantly decreased ventilatory index (VI) during the first 24 hours after treatment, which reflect the decreased requirement for ventilatory support. Chest radiograph scores significantly improved within 24 hours after treatment compared with pretreatment scores. In this trial, we found that a single intratracheal dose of surfactant-TA given to infants with HMD resulted in improved respiratory status and radiographic findings during the first 24 hours after treatment.

Blood Gas Analysis↗
PubMed1989

Ketamine potentiates nondepolarizing neuromuscular relaxants in a primate.

Ketamine has many neuromuscular effects in vitro. Its neuromuscular effects in vivo have been controversial and inconsistent. To systematically examine its neuromuscular effects over a wide dose range and its interaction with all popular nondepolarizing neuromuscular relaxants, the effects of ketamine 2, 5, and 10 mg/kg IV were studied on a continuous but incomplete (50%) neuromuscular block preestablished by an IV infusion of d-tubocurarine, atracurium, vecuronium, and pancuronium. Indirectly stimulated adductor pollicis muscle response of monkeys anesthetized with 0.5-1.0% halothane in oxygen were quantified. Ketamine in the absence of a neuromuscular relaxant had no effect on the thumb twitch. In a dose-dependent manner, ketamine significantly enhanced the 50% depression of the thumb twitch preestablished by a constant IV infusion of each of the four muscle relaxants studied. Ketamine 2 mg/kg potentiated the neuromuscular relaxants in the following order of magnitude: vecuronium greater than atracurium greater than d-tubocurarine greater than pancuronium. However, with a 10 mg/kg dose of ketamine, pancuronium became as potentiated as was vecuronium, i.e., pancuronium = vecuronium greater than atracurium greater than d-tubocurarine. It is concluded that in the primate, ketamine potentiates all nondepolarizing muscle relaxants in a dose-dependent manner.

Animals↗
PubMed1989

Profile matching and profile subtraction: application of computer-based image analysis system for two-dimensional electrophoresis gels.

The microcomputer-based image analysis system IB-1000 (developed by Indiana Biotech, Highland, IN) for two-dimensional electrophoresis gels has been described previously (9). It allows the user to compare protein spots between two profiles and identify those spots that are commonly shared in both profiles. This report describes two applications of the system's global comparison routine-profile matching and profile subtraction. This application is able to subtract commonly shared spots from one profile, creating a new profile made up by the unmatched spots in the other profile. These applications can be employed in a large variety of research projects.

Animals↗
PubMed1989

Development of behaviorally-based policy guidelines for the promotion of exercise.

We describe the results of a project to develop policy guidelines to promote increased levels of participation in regular physical activity in Australia. Theories of behavior change, and research findings concerning factors influencing the adoption and maintenance of exercising, were used as an information base for policy development. This information was presented and organized in the form of eleven behaviorally-based principles designed to be of use to practitioners, administrators and policy makers. Nine policy recommendations were developed from these principles, and from the contributions of people with practical administrative and political expertise in the field. Specific, focused campaigns, the provision of pleasant and convenient facilities, and an awareness of the process of behavior change and of the limitations imposed by environmental and social factors were emphases of the final recommendations. These may have relevance for similar work in North America and other developed countries. Some comments on the process involved in moving from an interpretation of behavior-change theories and basic research to the development of usable recommendations are offered. The project illustrates an approach to using a behavioral-science knowledge base for the development of public health principles and policies which have the potential to be of practical use.

Australia↗
PubMed1989

Low antigen density leukemia cells: selection and comparative resistance to antibody-mediated marrow purging.

Low tumor-associated antigen (TAA) expressing tumor cells present an obstacle to effective antibody directed purging of tumor cells from bone marrow. In this study, a comparison was made of the efficiency with which low TAA expressing leukemia cells could be depleted using two monoclonal antibody (MoAb) directed purging techniques: 1) complement (C)-mediated cytolysis, and 2) physical separation using magnetic microspheres. Low TAA sublines were selected from a cultured human leukemia cell line by growing out cells remaining after treatment with anti-TAA and C, or after immunomagnetic (IM) purging. IM-selected sublines showed lower TAA expression than did C-selected sublines, and sublines resulting from multiple selections expressed less TAA than those that had only been through one selection. These sublines were then examined for sensitivity to C or IM purging. The highly selected, lowest TAA expressing sublines were markedly resistant to both IM and C. Less selected sublines were resistant to C, but not to IM. In both techniques, addition of MoAbs against a second TAA restored the efficiency of purging to that observed with the parental line. When low TAA subline cells were seeded into simulated bone marrow and subjected to purging, C-mediated lysis removed less than 40% of leukemia cells, whereas IM purging removed 85% of the cells. These results indicate that there are low antigen density cells that are resistant to C-mediated purging, but which retain sensitivity to IM removal.

Antibodies, Monoclonal↗