Biomedical subjects

C Choo

Publications and source records attributed to C Choo.

4 recordsLinked to original sources

PubMed1999

Extracellular matrix proteins protect small cell lung cancer cells against apoptosis: a mechanism for small cell lung cancer growth and drug resistance in vivo.

Resistance to chemotherapy is a principal problem in the treatment of small cell lung cancer (SCLC). We show here that SCLC is surrounded by an extensive stroma of extracellular matrix (ECM) at both primary and metastatic sites. Adhesion of SCLC cells to ECM enhances tumorigenicity and confers resistance to chemotherapeutic agents as a result of beta1 integrin-stimulated tyrosine kinase activation suppressing chemotherapy-induced apoptosis. SCLC may create a specialized microenvironment, and the survival of cells bound to ECM could explain the partial responses and local recurrence of SCLC often seen clinically after chemotherapy. Strategies based on blocking beta1 integrin-mediated survival signals may represent a new therapeutic approach to improve the response to chemotherapy in SCLC.

Amino Acid Chloromethyl Ketones↗

PubMed1996

Correction of oriental epiblepharon by anterior lamellar reposition.

Epiblepharon commonly occurs in Oriental infants and children, but usually corrects itself with age. Epiblepharon in adults is not uncommon and may be misdiagnosed or detected late. It causes symptoms of ocular irritation and inferior punctate corneal epithelial erosion. These can persist if surgical treatment is ineffective. A series of 15 lower lid epiblepharon in 10 adults is presented with the clinical features and surgical treatment by anterior lamellar reduction and repositioning. The surgical technique is discussed. All patients had significant symptomatic relief and correction of lash-corneal touch. Among 15 cases of epiblepharon, 3 with residual trichiasis post-operatively were further corrected by skin reduction and debulking of pretarsal orbicularis oculi to achieve total correction. Adequate skin reduction and debulking of orbicularis oculi, especially the pretarsal muscle, are essential in the anterior lamellar repositioning and effective correction of this condition.

Adolescent↗

PubMed1994

Changes in spinal reflex excitability in a countermanded timed response task.

Subjects (N = 8) performed a timed response task in which they attempted to synchronize an impulsive foot-press response with the last in a series of four regularly spaced tones. In Experiment 1, the response was countermanded on one third of the trials (stop trials) by a stop signal that appeared at a predetermined delay after the third tone. No stop signal appeared on the remaining trials (go trials). All subjects showed a systematic transition from withholding the response on stop trials in which the stop signal appeared shortly after the third tone to executing the response on trials in which a single stop signal delay had been chosen so that a response would be made on about 50% of the stop trials. We elicited Hoffmann (H) reflexes from the soleus muscle on all trials to determine whether the reflexes were augmented on occasions on which a response was prepared but withheld. Mean H-reflex amplitudes on go trials and on stop trials on which the response was executed were similar and showed a marked augmentation beginning about 250 ms before response onset; mean H-reflex amplitudes on stop trials on which the response was withheld showed less pronounced augmentation. Inspection of individual H-reflex amplitudes revealed that on stop trials on which the response was withheld the reflexes could be augmented to the same extent as on trials on which the response was executed. This dissociation of H-reflex augmentation and response execution shows that H-reflex augmentation reflects a controlled response process. Ballistic response processes therefore must be limited to a brief duration.

Journal Article↗

PubMedDate not supplied

Reduced glucose degradation products in bicarbonate/lactate-buffered peritoneal dialysis solutions produced in two-chambered bags.

OBJECTIVES: The aims of the current study were: (1) to determine the effects of peritoneal dialysis (PD) solutions at different glucose concentrations on the growth of cultured cells; (2) to determine whether a bicarbonate/lactate-based solution, as a result of the configuration of its components during heat sterilization in a two-chambered bag, was lower in glucose degradation products than a corresponding lactate-based PD solution; and (3) to determine whether lower glucose degradation corresponded to a decreased inhibition of cell growth. DESIGN: Growth inhibition of cells exposed to lactate-based PD solutions at three different glucose concentrations was determined. Bicarbonate/lactate-based and lactate-based solutions at high glucose concentration (3.86%) were further analyzed for presence of glucose degradation products and inhibition of cell growth. METHODS: Cell growth was determined by neutral red uptake, measured by optical density at 540 nm. Glucose degradation to acetaldehyde or fructose was determined by gas chromatography-mass spectroscopy and high-performance liquid chromatography. RESULTS: Only 3.86% glucose lactate-based PD solution caused significant inhibition of cell growth (p < 0.05). The heat-sterilized, bicarbonate/dlactate-based solution (3.86% glucose) had lower levels of fructose and acetaldehyde than a conventional heat-sterilized, lactate-based solution with the same glucose concentration. Growth of cultured cells exposed to the bicarbonate/lactate-based solution was significantly improved (p < 0.05) over growth in the conventional solution. CONCLUSIONS: The bicarbonate/lactate-based solutions, manufactured and heat-sterilized in two-chambered bags, were lower in glucose degradation products than that corresponding lactate-based PD solutions, and demonstrated improved in vitro biocompatibility as measured by the growth of cultured cells.

Animals↗