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Biomedical subjects

C T Lin

Publications and source records attributed to C T Lin.

At least 55 records · Page 3Linked to original sources
PubMed2001

National survey of internal medicine residency programs of their 1st-year experience with the electronic residency application service and national resident match program changes.

BACKGROUND: The residency recruitment and selection process is a critical one for residency programs and medical students. In 1999, internal medicine programs conducted the residency match on the Web for the first time using the Electronic Residency Application Service (ERAS). PURPOSE: The authors wished to study the impact of this change on house staff recruitment and quality of match. METHOD: A Web-based survey with e-mail, paper, and fax reminders was sent to all 407 internal medicine residency programs after the 1999 match. RESULTS: Eighty-six percent of reporting programs found the screening of applicants easier. The overall number of applicants varied greatly (48% of programs reported more applicants; 32% reported fewer). The quality of final match was rated the same as previous years by 47%, better by 38%, and worse by 15%. CONCLUSIONS: The transition to ERAS was successful in internal medicine. However, there are several areas that were identified that will improve the ERAS process as it evolves.

Data Collection↗
PubMed2001

Personalized remedial intensive training of one medical student in communication and interview skills.

BACKGROUND: Medical students found to be deficient in communication and interview skills pose a difficult remediation challenge. There is no standard way to address such deficiencies. The authors describe the development and implementation of an intensive remedial curriculum. DESCRIPTION: A 2nd-year student found deficient in communication skills was held back for a year and paired with a clinical preceptor for intensive skills training, including a weekly precepted clinic, structured readings, standardized patient (SP) exercises, communications workshops, and end-of-year standardized clinical evaluations. EVALUATION: The student's self-assessment and the preceptor's assessments of communication skill gradually improved over the year. The student improved through a progression of SP exercises focusing on specific communication skills. The student passed a final evaluation exercise with an excellent rating from the SP and the preceptor. CONCLUSIONS: This multistrategy approach to improve communication skills can be applied to other students and in other institutions. Based on the Bayer Institute communication workshops and integrated coaching techniques, the material forms a framework to help deficient students to become proficient in communication and interviewing skills.

Communication↗
PubMed2001

Screw-in atrial lead in a sick sinus syndrome patient with anomalous inferior vena cava.

Anomalous inferior vena cava without intracardiac anomaly is an unusual condition. Herein, we report a 48-year-old female with left-sided inferior vena cava and azygous continuation. accompanied by sick sinus syndrome. This anomaly resulted in difficulty in implanting a traditional hook-on atrial lead. Atrial lead dislodgment occurred repeatedly soon after implanting the pacemaker because of an anomalous zygous vein draining into the superior vena cava, making a giant connection with the right atrium, thus eliminating the space of the atrial appendage for lead lodgment. Finally, we attempted to utilize a screw-in atrial lead in this patient and she is currently doing well. We therefore suggest that a screw-in atrial lead should be taken into account for such patients in order to obtain a stable fixation.

Azygos Vein↗
PubMed2001

Klebsiella pneumoniae orbital cellulitis.

We present a case of orbital cellulitis due to Klebsiellapneumoniae infection. The computed tomography revealed cellulitis over the right cheek with abscess formation in the right eyelid and ipsilateral chronic obstructive sinusitis. Incision and drainage of orbital abscess and functional endoscopic sinus surgery were performed sequentially. Klebsiella pneumoniae was confirmed via culture from these two lesions. The patient achieved complete remission without sequalae after surgical intervention and systemic antibiotics. We describe a successfully treated case of Klebsiella pneumoniae orbital cellulitis, which has never been reported before.

Cellulitis↗
PubMed2000

Taxol reduces cytosolic E-cadherin and beta-catenin levels in nasopharyngeal carcinoma cell line TW-039: cross-talk between the microtubule- and actin-based cytoskeletons.

Taxol affects microtubule dynamics by promoting microtubule assembly. To obtain a better insight into possible cross-talk between the microtubule- and actin-based cytoskeletons, we studied the short-term effects of Taxol treatment on the expression of actin and the E-cadherin/catenin complex in the nasopharyngeal carcinoma cell line TW-039 using immunofluorescence, immunoprecipitation, and immunoblotting methods. Morphologic changes in actin filaments, including ventral actin clumps and perijunctional actin blebs, were seen at Taxol concentrations > or =1 microM. Levels of detergent-soluble E-cadherin fell to 53% or 58% compared to controls in cells treated, respectively, with 1 or 5 microM Taxol, while levels of detergent-soluble beta-catenin fell to 76% or 74%. Levels of the detergent-soluble pool of alpha- and gamma-catenin and the detergent-insoluble pool of the E-cadherin/catenin complex were unchanged by Taxol treatment and no significant difference was seen in the levels of adenomatous polyposis coli or glycogen synthase-3beta or tyrosine phosphorylation patterns. These results suggest that modulation of microtubule dynamics by Taxol may have effects on the expression of actin and the cytosolic E-cadherin and beta-catenin in nasopharyngeal carcinoma cells through pathways not involving the phosphorylation of beta-catenin.

Actins↗
PubMed2000

Mechanism of abnormal elastin gene expression in the pinguecular part of pterygia.

Elastodysplasia and elastodystrophy are two known manifestations in the conjunctival, ie, pinguecular, part of pterygia. But the mechanisms are still not understood. The purpose of this study is to investigate the mechanism of enhanced elastin gene expression in fibroblasts from the pinguecular part of pterygia, which is related to abnormal elastic fiber expression in the pinguecular part of pterygia. Elastin in surgical specimens of normal conjunctiva and the pinguecular part of pterygia from age-matched patients was detected by immunohistochemical staining. Northern hybridization and quantification of radiolabeled tropoelastin were performed in conjunctival fibroblasts cultured under different doses of ultraviolet (UV) B irradiation, and in cultured pinguecular fibroblasts from pterygia. In vitro translation was also performed to analyze the tropoelastin production in rabbit reticulocyte lysate. The level of tropoelastin in reticulolysates from UV-treated conjunctival and pinguecular fibroblasts of pterygia was higher than in normal conjunctival fibroblasts. The coding sequence and 3'- untranslated region of tropoelastin mRNAs were amplified by reverse transcription-polymerase chain reaction, and mutations were checked by DNA sequencing. Immunohistochemical staining revealed elastin in pinguecular subepithelial connective tissues of pterygia, but not in normal conjunctiva. Tropoelastin mRNA levels were not elevated in cultured pinguecular or conjunctival fibroblasts with or without ultraviolet B irradiation. However, tropoelastin synthesis was enhanced in culture medium of pinguecular and UV-irradiated conjunctival fibroblasts, but not in normal conjunctival fibroblasts. Direct DNA sequencing revealed mutations in the 3'-untranslated region but not in the coding sequence of tropoelastin mRNA, in both pinguecular and UV-irradiated conjunctival fibroblasts. The increased expression of tropoelastin in pinguecular and UV-irradiated fibroblasts is not a result of increased levels of steady-state mRNA, but is a result of posttranscriptional modification of tropoelastin.

3' Untranslated Regions↗
PubMed2000

Laser-induced acoustic emissions in experimental dental composites.

A laser thermoacoustic technique was innovated to evaluate laser-induced acoustic emissions (AEs) in experimental dental composites aged with 75% ethanol solution. Experimental composite systems of 75/25 BisGMA/TEGDMA resin filled with 0, 12.6, 30.0, and 56.5 vol% of 8-microm silanized and unsilanized BaSiO6 were analyzed. The sample size was 4.65 mm (diameter) x 0.5 mm (thick). Aging effects of immersing in 75% ethanol for up to 14 h on AEs were then evaluated. A continuous-wave CO2 laser was used to heat the samples. Acoustic emissions were collected as a function of filler fraction, laser power, silanization, and immersion time. Onset of burst-pattern acoustic signals characteristic of fracturing occurred at different laser powers for different tested groups. Acoustic emissions generally increased with laser power, in which lower laser powers produced low-amplitude (45-50 dB) signals; the amplitude distribution (50-85 dB) became more extensive as laser powers increased. After immersion, the lower laser powers could produce the same phenomenon. The higher the filler fraction, the fewer AEs generated. A large percentage AE reduction due to silanization was noted as a function of filler fraction. Unsilanized specimens showed more thermal damages than did silanized ones.

Acoustics↗
PubMed2000

Finite element analysis of thermo-debonding mechanism in dental composites.

Finite element method (FEM) has been extensively used for evaluating interfacial status inside biomaterials. This study using FEM was designed to evaluate the thermal stress behavior of a filler-matrix interface. The results were then compared to those of a previous study obtained by a laser thermoacoustic technique (LTAT). The experimental systems (75/25 Bis-GMA/TEGDMA resin reinforced with 0, 25, 50, and 75 wt% 8-microm silanized/unsilanized BaSiO6) as used in the previous study were modeled in this study. The established finite element models were based on coefficient of thermal expansion (CTE) Mismatch Phenomenon. The mechanical properties of the silane coupling agent, such as elastic modulus and thermal expansion coefficient used in the silanized model, were assumed to have optimal heat flux transfer. A third (imaginary) material was proposed to block the transfer of thermal stress between the filler and matrix in the unsilanized model. The thermal load simulation was based on steady-state thermal analysis. The results showed that: (1) The strain energy and interfacial shearing stress calculated from FEM validate the results from the previous LTAT study. (2) Comparing the stress distribution of silanized and unsilanized FEM models, the acoustic signals in LTAT study are mainly derived from debonding of the filler-matrix interface of silanized specimens, and from the matrix area of unsilanized specimens. Based on results to date, we conclude that the finite element method may be a powerful tool for exploring thermoacoustic mechanisms of dental composites.

Acoustics↗
PubMed2000

Molecular cloning, characterization, and expression of a cDNA coding Copper/Zinc superoxide dismutase from black porgy.

A full-length complementary DNA (cDNA) clone encoding a putative copper/zinc superoxide dismutase (Cu/Zn-SOD) was amplified by a Polymerase Chain Reaction (PCR) based technique from cDNA synthesized from black porgy, Acanthopagrus schlegeli, mRNA. Nucleotide sequence analysis of this cDNA clone revealed that it comprised a complete open reading frame coding for 154 amino acid residues. The deduced amino acid sequence showed slightly higher identity (72.8-78.1%) with shark and swordfish Cu/Zn-SOD than with Cu/Zn-SOD from mammalian (68.1-70.7%) and plant (55.5-56.5%) sources. The residues required for coordinating copper and zinc are conserved as they are among all reported Cu/Zn-SOD sequences. The deduced amino acid sequence lacks mitochondria targeting sequence, which suggests that the black porgy cDNA clone encodes a cytosolic Cu/Zn-SOD. The coding region of Cu/Zn-SOD from black porgy was introduced into an expression vector, pET-20b(+), and transformed into Escherichia coli AD494(DE3)pLysS. A predominant achromatic zone was detected by activity staining of native PAGE. This indicates that the Cu/Zn-SOD cDNA clone can express active Cu/Zn-SOD enzyme in E. coli.

Amino Acid Sequence↗
PubMed2000

Cloning and expression of a cDNA coding for catalase from zebrafish (Danio rerio).

A full-length complementary DNA (cDNA) clone encoding a catalase was amplified by the rapid amplication of cDNA ends-polymerase chain reaction (RACE-PCR) technique from zebrafish (Danio rerio) mRNA. Nucleotide sequence analysis of this cDNA clone revealed that it comprised a complete open reading frame coding for 526 amino acid residues and that it had a molecular mass of 59 654 Da. The deduced amino acid sequence showed high similarity with the sequences of catalase from swine (86.9%), mouse (85.8%), rat (85%), human (83.7%), fruit fly (75.6%), nematode (71.1%), and yeast (58.6%). The amino acid residues for secondary structures are apparently conserved as they are present in other mammal species. Furthermore, the coding region of zebrafish catalase was introduced into an expression vector, pET-20b(+), and transformed into Escherichia coli expression host BL21(DE3)pLysS. A 60-kDa active catalase protein was expressed and detected by Coomassie blue staining as well as activity staining on polyacrylamide gel followed electrophoresis.

Amino Acid Sequence↗
PubMed2000

Response of nasopharyngeal carcinoma cells to Epstein-Barr virus infection in vitro.

Many nasopharyngeal carcinoma (NPC) biopsy specimens contain Epstein-Barr virus (EBV). However, the response of NPC cells to EBV infection in vitro and in vivo is not well characterized. In this experiment we infected NPC cells with EBV particles through endocytosis of a complex of EBV immunoglobulin A (IgA) secretory component (SC) protein to observe the response of host cells to the foreign viral infection in vitro. We found that EBV particles were endocytosed and stabilized in NPC nuclei 24 hours after infection; the EBV genomes were then gradually decreased after serial passages within 3 to 4 weeks by the following pathway: the EBV genomes first moved toward the nuclear envelope from the center of the nucleus; after crossing the nuclear envelope, they moved into the cytoplasm and toward the plasma membrane and were discharged by exocytosis. At the 10th day of EBV infection, EBV-latent membrane protein-1 and Epstein-Barr nuclear antigen (EBNA)-1 protein expressions could be detected, but not EBV-viral capsid antigen. Observation of EBNA-1 protein and host growth factor and cytokine gene expressions in the weeks after incubation revealed that the EBNA-1 protein expression was decreased proportionally with decrease of EBV genome. The mRNA expression of epithelial growth factor receptor, transforming growth factor (TGF)-alpha, interleukin (IL)-1beta, IL-6, and granulocyte-macrophage colony-stimulating factor increased within 1 to 2 weeks after infection, and gradually recovered to the original level at 3 to 4 weeks, whereas the mRNAs of TGFbeta1, TGFbeta receptor type I (TGFbetaRI), TGFbetaR type II, IL-8, and tumor necrosis factor-alpha remained unchanged. It is concluded that in vitro EBV infection in NPC cells results in increase of certain growth factor and cytokine gene expressions in host cells. The change in gene expression returns to the original level approximately 3 to 4 weeks after infection because of exocytosis of EBV DNA by the infected cells through an unidentified mechanism.

Base Sequence↗
PubMed2000

Degradation of repaired denture base materials in simulated oral fluid.

This in vitro study evaluates the degradation of repaired denture bases upon immersion in a simulated oral fluid. Denture base materials (Luciton 199), after being repaired by Repair Material and Triad, using three different joint surface designs (butt, round and 45 degrees bevel), were immersed onto 99.5 vol.% ethanol/water solution (with similar solubility parameter) for various amounts of time (0-72 h). The flexural loads of the six combination of groups were measured by the three-point bending tests using a universal testing machine. Acoustic emission (AE) during sample fracturing were processed using the MISTRA 2001 system. The fracture pattern and surface details of the interface were examined with a scanning electronic microscope (SEM). Data were analysed using three-way ANOVA and Tukey LSD tests. SEM micrographs of the fracture interface were used to differentiate the fracture mode. The flexural loads (2.72 +/- 0.51 Kgf) of the round joint specimens were significantly higher (P< 0.05) than those (butt: 1.66 +/- 0.38 Kgf, 45 degrees bevel: 1.93 +/- 0.41 Kgf) of the other two designs. This corresponds to the microscopic examination in which more cohesive failure mode was found for the round joint group after storage. The flexural loads (2.54 +/- 0.39 Kgf) of the specimens repaired with Triad were significantly higher (P < 0.05) than those (1.59 +/- 0.40 Kgf) of specimens repaired with Repair Material. Significant progressive reduction of the flexural load and/or AE signals of the specimens was noted in proportion to the length of time of the immersion in the simulated oral fluid. Mechanical strength of a denture base repaired with a round joint design and light-cured material is significantly higher after immersion in simulated oral fluid.

Acoustics↗
PubMed2000

Influence of silanization and filler fraction on aged dental composites.

The effect of silanization and filler fraction on the mechanical properties of aged dental composites was investigated. Experimental composites (75/25 Bis-GMA/TEGDMA resin reinforced with 0, 12.6, 30.0, and 56.5 vol% 8 microm silanized/unsilanized BaSiO6) were fabricated into 4.7 mm diameter x 2.2 mm thick discs and 3.5 mm diameter x 7.3 mm thick discs for diametral tensile and compressive tests, respectively. The effect of immersion in 75% ethanol at 37 degrees C for 0-30 days on the diametral tensile strength (DTS) and compressive strength (CS) of the samples was evaluated and analysed by ANOVA and Tukey LSD test. The fracture interface between filler and resin matrix was then examined by scanning electron microscope. Results and subsequent statistical evidence from DTS (18.6+/-7.6 MPa, silanized versus 11.7+/-2.6 MPa, unsilanized) and CS (85.1+/-29.7 MPa, silanized versus 56.0+/-11.3 MPa, unsilanized) strongly implies that silanization may greatly enhance the mechanical properties of the resin composites. Furthermore, it also shows that both DTS and CS increased proportionally as the filler fraction of the composites increased. However, in the unsilanized groups, DTS decreased (up to 40%) as the filler fraction increased, and CS showed no relevance to the filler fraction at all. As for the influence of aging, it was found that both DTS and CS showed a significant decrease after immersion in 75% ethanol, and silanization heavily correlated with the filler fraction of aged-resin composites. Microscopic examination of the fractured samples showed that failure primarily occurred within the resin matrix per se for silanized composites and adjacent to the filler particles for unsilanized composites. All the evidence points to the conclusion that mechanical properties of aged-resin composites can be greatly influenced by silanization and the filler fraction.

Analysis of Variance↗
PubMed2000

Acoustic emissions generated in aged dental composites using a laser thermoacoustic technique.

The heating up of dental composites by laser will produce acoustic emissions (AEs) that may be related to fracture mechanisms in the composites. It has been proved that the mechanical properties of dental composites are affected by storage in food simulating liquids, i.e. 75% ethanol, which has a solubility parameter approximating to that of bisphenol glycidyl dimethacrylate (BisGMA) resin. A new method was innovated to evaluate the laser-induced AEs in dental composites aged by 75% ethanol solution. Model systems (50/50 BisGMA/TEGDMA resin filled with 0% and 75 wt.% 5-10 microm silanized BaSiO6) as well as three commercial composites (Marathon One, Z100 and Herculite XRV) were used in this study. Nine samples acting as the control group were tested to establish the correlation of AEs to laser power. The effect of ageing by immersion in 75% ethanol on AEs and diametral tensile strength (DTS) was then evaluated. A quasi-continuous wave CO2 laser was used to heat up the composites. AEs of frequency 100-200 kHz were collected, filtered, recorded and processed using a 4610 Smart Acoustic Monitor. Burst patterns, which formally were assumed to be correlated to fracture mechanisms, were also identified from the data obtained at laser power > or = 5 W for commercial composites and > or = 4 W for model systems. Higher laser powers cause the AE to increase for all composites except unfilled model resin. AEs as a function of power for all aged systems were flat (< 100 events) below 4 W. Emissions then rose sharply to > 1000 events at 7.1 W. Statistically significant differences were found between the AEs obtained at 5 W (commercial composites) and those at 4.3 W (model systems) for material systems and storage times. Marathon One was less affected by the laser and an abrupt change in AE was found between days 0 and 7 of storage for all commercial composites. The AE value from the unfilled model resin was found to be significantly different from that of the model composites. However, they showed an increase in AEs with length of storage time, which was inversely associated with the decreased tendency of their immersed DTS values. Laser-induced AEs may be a valuable adjunct to conventional mechanical testing.

Acoustics↗
PubMed2000

Effect of temperature and flux concentration on soldering of base metal.

The present study used the acoustic emission (AE) technique to evaluate interactions among soldering temperature, flux treatment, and the resultant ultimate tensile strength (UTS). Scanning electron microscopy (SEM) was used to examine fracture surfaces of the solder joints. Specimens were cast from removable partial denture alloy and then placed in a jig with a gap distance of 1.0 mm. A high-frequency soldering machine with an optical pyrometer was used for soldering at 1150 degrees C and 1200 degrees C, respectively. The flux concentrations were 67% and 75%. The soldered specimens were subjected to tensile test at a crosshead speed of 0.05 mm/min. During testing, acoustic emissions in the frequency range of 100--1200 kHz were collected, filtered, recorded, and processed by a sensing device. The results were analysed by ANOVA and Tukey LSD test. UTS at different temperatures showed no significant difference according to either mechanical or acoustic results. But in the 1200 degrees C group, the UTSs and AE counts showed significant differences (P<0.05) at both flux concentrations. SEM showed that the 1200C group had better dendritic crystal structure than did the 1150 degrees C group. In the 1200 degrees C group specimens with 67% flux had fewer flux inclusion bodies and dendritic crystals than did specimens with 75% flux. The 75% flux subgroup produced high-amplitude (60--70 dB) acoustic signals within the elastic deformation zone, while the 67% flux subgroup produced similar signals within the plastic deformation zone, either beyond the 0.2% yield point or before fracture.

Acoustics↗
PubMed2000

Alternative/complementary medicine: wider usage than generally appreciated.

OBJECTIVE: To test the hypothesis that there is substantial use of a practitioner of alternative/complementary medicine by patients traditionally considered to be underserved. DESIGN: Cross-sectional, self-administered survey study. SETTINGS: Three university hospital-affiliated general ambulatory clinics serving patients of different socioeconomic status and racial origin. SUBJECTS: Five hundred and thirty-six (93% of those attending) consecutive clinic attendees. OUTCOME MEASURES: Past use and desired future use of one or more practitioners of five modalities of alternative/complementary medicine and willingness to pay for these modalities out-of-pocket. RESULTS: Past usage and desired future usage of one or more practitioners of alternative/complementary medicine was comparable at the three clinic sites despite wide differences in socioeconomic status and willingness/ability to pay out-of-pocket for these services. Multivariable analyses revealed lower self-rated health status and female gender (both p < 0.006) but not income, race, age or education as independent, significant predictors of use of a practitioner of alternative/complementary medicine. CONCLUSION: Usage of alternative/complementary medicine is not confined to any well-circumscribed socioeconomic group and is common in patients often considered to be underserved. Self-assessed lower health status is significantly and independently associated with use of a practitioner of alternative/complementary care.

Adolescent↗
PubMed2000

Recognition of patient referral desires in an academic managed care plan frequency, determinants, and outcomes.

OBJECTIVE: To determine the frequency and determinants of provider nonrecognition of patients' desires for specialist referral. DESIGN: Prospective study. SETTING: Internal medicine clinic in an academic medical center providing primary care to patients enrolled in a managed care plan. PARTICIPANTS: Twelve faculty internists serving as primary care providers (PCPs) for 856 patient visits. MEASUREMENTS AND MAIN RESULTS: Patients were given previsit and postvisit questionnaires asking about referral desire and visit satisfaction. Providers, blinded to patients' referral desire, were asked after the visit whether a referral was discussed, who initiated the referral discussion, and whether the referral was indicated. Providers failed to discuss referral with 27% of patients who indicated a definite desire for referral and with 56% of patients, who indicated a possible desire for referral. There was significant variability in provider recognition of patient referral desire. Recognition is defined as the provider indicating that a referral was discussed when the patient marked a definite or possible desire for referral. Provider recognition improved significantly (P <.05), when the patient had more than one referral desire, if the patient or a family member was a health care worker and when the patient noted a definite desire versus a possible desire for referral. Patients were more likely (P <.05) to initiate a referral discussion when they had seen the PCP previously and had more than one referral desire. Of patient-initiated referral requests, 14% were considered "not indicated" by PCPs. Satisfaction with care did not differ in patients with a referral desire that were referred and those that were nor referred. CONCLUSIONS: These PCPs frequently failed to explicitly recognize patients' referral desires. Patients were more likely to initiate discussions of a referral desire when they saw their usual PCP and had more than a single referral desire.

Colorado↗