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Biomedical subjects

C T Lin

Publications and source records attributed to C T Lin.

At least 37 records · Page 2Linked to original sources

CD8+ T cells, NK cells and IFN-gamma are important for control of tumor with downregulated MHC class I expression by DNA vaccination.

One of the major hurdles facing cancer immunotherapy is that cancers may downregulate expression of MHC class I molecules. The development of a suitable tumor model with downregulated MHC class I expression is critical for designing vaccines and immunotherapeutic strategies to control such tumors. We developed an E7-expressing murine tumor model with downregulated MHC class I expression, TC-1 P3 (A15). Using this model, we tested DNA and vaccinia vaccines for their ability to control tumors with downregulated MHC class I expression. We found that vaccination with DNA encoding E7 linked to Mycobacterial heat shock protein 70 (HSP70) generated a significant antitumor effect against TC-1 P3 (A15), while vaccination with E7/HSP70 vaccinia did not generate an appreciable antitumor effect. Lymphocyte depletion experiments revealed that both CD8+ T cells and NK cells were essential for the antitumor effect generated by E7/HSP70 DNA against TC-1 P3 (A15). Furthermore, tumor protection experiments using IFN-gamma knockout mice revealed that IFN-gamma was essential for the antitumor effect generated by E7/HSP70 DNA against TC-1 P3 (A15). Our results demonstrate that vaccination with E7/HSP70 DNA results in a significant antitumor effect against a neoplasm with downregulated MHC class I expression and the importance of CD8+ T cells, NK cells, and IFN-gamma in generating this antitumor effect.

Animals↗

Josephson plasma resonance and phonon anomalies in trilayer Bi2Sr2Ca2Cu3O10.

The far-infrared (FIR) c axis conductivity of a Bi2223 crystal has been measured by ellipsometry. Below T(c) a strong absorption band develops near 500 cm(-1), corresponding to a transverse Josephson plasmon. The related increase in FIR spectral weight leads to a giant violation of the Ferrell-Glover-Tinkham sum rule. The gain in c axis kinetic energy accounts for a sizable part of the condensation energy. We also observe phonon anomalies which suggest that the Josephson currents lead to a drastic variation of the local electric field within the block of closely spaced CuO2 planes.

Journal Article↗

Impact of a simple intervention to increase primary care provider recognition of patient referral concerns.

OBJECTIVE: To determine whether a brief previsit questionnaire about referral concerns can improve primary care provider (PCP) recognition of patient concerns and satisfaction with care. DESIGN: Sequential prospective study in the internal medicine clinic of an academic medical center providing primary care to patients enrolled in a gatekeeper-model managed care plan. PARTICIPANTS AND METHODS: Twelve faculty internists serving as PCPs for 1495 consecutive patient visits. Patients were given a previsit questionnaire asking about referral need and rationale and a postvisit questionnaire asking about discussion of referral concern and visit satisfaction. Providers were given a postvisit questionnaire asking whether a referral was discussed and made and about visit satisfaction. In the control phase, patient previsit questionnaires remained confidential, whereas in the intervention phase PCPs were shown the previsit questionnaires at the time of encounter. RESULTS: The intervention significantly increased PCP referral recognition from 61% to 81% (P < .001) and was associated with increased visit satisfaction (P = .05). Satisfaction of PCPs with the referral discussion, overall rate of referral, and visit duration were not affected by the intervention. CONCLUSIONS: Using a brief previsit questionnaire about patient referral concerns increases PCP recognition of such concerns. The intervention does not adversely affect PCP satisfaction with the referral discussion or the overall referral rate and may enhance patient visit satisfaction.

Academic Medical Centers↗

The third person in the room: frequency, role, and influence of companions during primary care medical encounters.

OBJECTIVE: We wanted to characterize patient accompaniment to medical encounters and to explore the rationale and influence of the companion on the primary care medical encounter. STUDY DESIGN: This was a descriptive study. POPULATION: Academic general internal medicine physicians, patients, and patient companions participated. OUTCOMES MEASURED: We measured the frequency of waiting and examination room companions, the reasons for accompaniment, the influence on the encounter, and the overall helpfulness of the companion as assessed by patients and companions. We also determined the physicianamprsquos assessment of the companionamprsquos influence, helpfulness, and behavior during the encounter. RESULTS: Companions were in the examination room for 16% of visits; 93% were family members. The rationales for waiting and examination room companions were to help with transportation, provide emotional support, and provide company. Examination room companions helped communicate concerns to the physician, remember the physicianamprsquos advice, make decisions, and communicate their own concerns to the physician. Patients believed that examination room companions influenced 75% of medical encounters, mainly by improving communication between physician and patient. Physicians agreed that examination room companions favorably influenced physician and patient understanding (60% and 46% of encounters, respectively). Patients indicated that waiting and examination room companions were very helpful for 71% and 83% of visits, respectively. CONCLUSIONS: Companions frequently accompany patients to their primary care medical encounters. They are often family members, and they assume important roles in enhancing patient and physician understanding.

Adolescent↗

Modulation of NO and cytokines in microglial cells by Cu/Zn-superoxide dismutase.

The activation of microglial cells in response to neuropathological stimuli is one of the prominent features of human neurodegenerative diseases. Cytokines such as IL-1 beta and TNF-alpha and inflammation-related enzymes such as inducible nitric oxide synthase are usually induced during the activation of microglial cells. We investigated the modulation of the activation of microglial cell by transfecting a Cu/Zn-SOD cDNA into BV-2 cells. Parental and transfected BV-2 cells were then subjected to LPS stimulation. The results showed that in Cu/Zn-SOD-transfected BV-2 cells, the expression and activity of Cu/Zn-SOD increased. On the other hand, upon activation by LPS, these cells produced less NO, IL-1 beta, and TNF-alpha than the parental microglial cells. This finding suggests that superoxide may be an early signal triggering the induction of cytokines and that the transfected Cu/Zn-SOD may provide a neuroprotective function via suppression of microglial activation. In addition, this approach may provide a rationale for the development of treatments for neurodegenerative diseases.

Animals↗

Inverted repeats as genetic elements for promoting DNA inverted duplication: implications in gene amplification.

Inverted repeats are important genetic elements for genome instability. In the current study we have investigated the role of inverted repeats in a DNA rearrangement reaction using a linear DNA substrate. We show that linear DNA substrates with terminal inverted repeats can efficiently transform Escherichia coli. The transformation products contain circular inverted dimers in which the DNA sequences between terminal inverted repeats are duplicated. In contrast to the recombination/rearrangement product of circular DNA substrates, which is exclusively one particular form of the inverted dimer, the rearrangement products of the linear DNA substrate consist of two isomeric forms of the inverted dimer. Escherichia coli mutants defective in RecBCD exhibit much reduced transformation efficiency, suggesting a role for RecBCD in the protection rather than destruction of these linear DNA substrates. These results suggest a model in which inverted repeats near the ends of a double-strand break can be processed by a helicase/exonuclease to form hairpin caps. Processing of hairpin capped DNA intermediates can then yield inverted duplications. Linear DNA substrates containing terminal inverted repeats can also be converted into inverted dimers in COS cells, suggesting conservation of this type of genome instability from bacteria to mammalian cells.

Animals↗

Suppression of gene amplification and chromosomal DNA integration by the DNA mismatch repair system.

Mismatch repair (MMR)-deficient cells are shown to produce >15-fold more methotrexate-resistant colonies than MMR normal cells. The increased resistance to methotrexate is primarily due to gene amplification since all the resistant clones contain double-minute chromosomes and increased copy numbers of the DHFR gene. In addition, integration of linearized or retroviral DNAs into chromosomes is also significantly elevated in MMR-deficient cells. These results suggest that in addition to microsatellite instability and homeologous recombination, MMR is also involved in suppression of other genome instabilities such as gene amplification and chromosomal DNA integration.

Adaptor Proteins, Signal Transducing↗

Is patients' perception of time spent with the physician a determinant of ambulatory patient satisfaction?

BACKGROUND: Time management in ambulatory patient visits is increasingly critical. Do patients who perceive a longer visit with internists report increased satisfaction? METHODS: Prospective survey of 1486 consecutively encountered ambulatory visits to 16 primary care physicians (PCPs) in an academic primary care clinic. Patients were queried regarding demographics, health status, perception of time spent before and after ambulatory visits, whether the physician appeared rushed, and visit satisfaction. Physicians were queried regarding time spent, estimated patient satisfaction, and whether they felt rushed. RESULTS: In 69% of 1486 consecutive visits, patient previsit expectation of visit duration was 20 minutes or less. Patient and PCP postvisit estimates of time spent significantly exceeded patient previsit time expectation. Patients who estimated that they spent more time than expected with the PCP were significantly more satisfied with the visit. When patient postvisit estimate of time spent was less than the previsit expectation, visit satisfaction was significantly lower independent of time spent. Patient worry about health and lower self-perceived health status were significantly associated with patient expectation for longer visits. Primary care physicians felt rushed in 10% of encounters. Although PCPs estimated patient satisfaction was significantly lower when they felt rushed, patient satisfaction was identical when PCPs did and did not feel rushed. Patients indicated that PCPs appeared rushed in 3% of encounters, but this perception did not affect patient satisfaction. CONCLUSION: Perceived ambulatory visit duration and meeting or exceeding patient expectation of time needed to be spent with the physician are determinants of patient satisfaction in an ambulatory internal medicine practice.

Ambulatory Care↗

Generation and analysis of canine retinal ESTs: isolation and expression of retina-specific gene transcripts.

Canine generalized progressive retinal atrophies (gPRA) are a group of degenerative retinal diseases that are a major cause of hereditary blindness in a number of dog breeds. The expressed sequence tag (EST) approach was used to identify and characterize potential candidate genes from canine retinal cDNA libraries. Both conventional and subtractive canine retinal cDNA libraries were constructed and analyzed. Differential hybridization was performed to identify abundantly retinal expressed cDNA clones. Sequences of both random and abundantly expressed clones were analyzed using GCG software and searched against GenEMBL databases. For genes of interest isolated from the libraries, Northern blotting and RT-PCR were performed to determine mRNA expression of the genes. DNA sequences from 85 differentially expressed clones and 100 random cDNAs were obtained and analyzed. A higher percentage of abundantly retina-expressed clones showed homology to database sequences compared with random clones (72 versus 43%). Five retinal genes and 2 anonymous retinal ESTs were selected to analyze mRNA expression. The five known genes, namely HRG4/unc119, cGMP-PDEA, transducin 1A, opsin, and sFRP2 showed retina-specific expression. In anonymous ESTs, clone p81 revealed retina-specific expression, while p3 showed expression in each of 14 canine tissues. Transcripts of the canine secreted frizzled related protein 2 (sFRP2) gene showed surprisingly high abundance in the canine retina. The isolated retinal ESTs here will be useful resources for further investigation of canine retinal function and canine genome mapping.

Animals↗

Resonant spin excitation in an overdoped high temperature superconductor.

An inelastic neutron scattering study of overdoped Bi(2)Sr(2)CaCu(2)O(8+delta) ( T(c) = 83 K) has revealed a resonant spin excitation in the superconducting state. The mode energy is E(res) = 38.0 meV, significantly lower than in optimally doped Bi(2)Sr(2)CaCu(2)O(8+delta) ( T(c) = 91 K, E(res) = 42.4 meV). This observation, which indicates a constant ratio E(res)/k(B)T(c) approximately 5.4, helps resolve a long-standing controversy about the origin of the resonant spin excitation in high temperature superconductors.

Journal Article↗

Applications of the telomerase assay in peritoneal washing fluids.

OBJECTIVE: The aim of this study was to detect telomerase activity in peritoneal ascites and to assess whether it can be used as an assistant tool for the early detection of ovarian cancer. METHODS: Telomerase activity was measured by TRAP assay in 47 patients with ovarian malignancies and 50 patients with benign uterine leiomyomas (control group). RESULTS: All 26 peritoneal washing cytology positive cases were telomerase positive. Of the 21 peritoneal washing cytology negative cases, 3 were telomerase positive. When these 3 were reevaluated for peritoneal cytology, malignant ascitis was identified in 1. All telomerase negative cases were negative for peritoneal washing cytology. The sensitivity and specificity of peritoneal cytology and telomerase testing in correlation with true malignant cells were 96 (26/27) and 100% (20/20) versus 100 (27/27) and 90% (18/20), respectively. The false negative rate of peritoneal cytology was 4.7% (1/21). The false positive rate of the telomerase test in relation to malignant ascites was 6.9% (2/29). CONCLUSION: Our preliminary results reveal a high sensitivity and specificity of both telomerase testing and conventional cytology in peritoneal fluids. Our data suggest that the telomerase test in peritoneal fluids can be used as an adjuvant to cytopathological methods in the diagnosis of malignant peritoneal ascites, particularly in cases of negative cytology. In these cases, a review of peritoneal histocytology is advised.

Adult↗

Thermo-debonding mechanisms in dentin bonding systems using finite element analysis.

The finite element method (FEM) has been extensively used in evaluating the interfacial status of biomaterials. We used FEM to explore the microscopic debonding mechanism of the dentin/hybrid layer/resin adhesive interface. The stress status of the local material was used as an index to judge whether the adhesive interface would develop a debonding mechanism. To generate the local stress concentration, the thermal boundary condition was applied to the model which has the phenomenon of the coefficient of thermal expansion (CTE) mismatch. The thermal boundary condition was used to emulute a previous study conducted with a laser thermoacoustic technique (LTAT). The materials, Scotchbond MP, Optibond, and Tenure bonding systems, used in the previous experiment were also tested in this study. The results show that interfacial debonding in the finite element model occurred through the hybrid layer for both the Scotchbond MP and Tenure systems, as well as within the adhesive layer itself for the Optibond system. These findings are compatible with observations by SEM obtained by LTAT. Another transformed model was created to test the "elastic cavity wall" concept. The result also confirms the importance of the elastic cavity wall concept. These compatible results between FEM and LTAT indicate that FEM can be a very useful supplement to thermoacoustic testing.

Biocompatible Materials↗

Value of human papillomavirus deoxyribonucleic acid testing after conization in the prediction of residual disease in the subsequent hysterectomy specimen.

OBJECTIVE: Our aim was to evaluate human papillomavirus deoxyribonucleic acid testing after conization in predicting residual disease in the subsequent hysterectomy specimen. STUDY DESIGN: A prospective study was conducted on 75 patients with grade 3 cervical intraepithelial neoplasia who had cone margins or endocervical curettage specimens showing disease and who elected to undergo hysterectomy after conization. All patients underwent high-risk human papillomavirus deoxyribonucleic acid testing by the Hybrid Capture II (Digene Corporation, Gaithersburg, MD) system before conization and at the time of hysterectomy (within 2-7 weeks after conization). The presence of human papillomavirus deoxyribonucleic acid in cells obtained by endocervical brush before hysterectomy was correlated with residual disease in the hysterectomy specimens. RESULTS: Of the 92 patients enrolled, 75 were eligible. Of these 75 patients, 52 (69.3%) had persistent human papillomavirus deoxyribonucleic acid after conization, and 27 (36.0%) of the 75 patients had residual cervical neoplasia in the hysterectomy specimens. Those with negative results for human papillomavirus deoxyribonucleic acid after conization were all (23/23) without residual disease in the uterus (100% negative predictive value). All those who had residual disease (27/27) had positive results for human papillomavirus deoxyribonucleic acid at the time of hysterectomy (100% sensitivity). Postconization human papillomavirus deoxyribonucleic acid status (odds ratio, 4.000; 95% confidence interval, 1.531-10.449; P =.005) and grade of dysplasia after endocervical curettage (classified as grade 2 cervical intraepithelial neoplasia or less severe disease vs grade 3 cervical intraepithelial neoplasia: odds ratio, 6.612; 95% confidence interval, 2.837-15.409; P =.0002) were significantly associated with residual tumor in the uterus. CONCLUSIONS: This prospective study confirms an excellent sensitivity and negative predictive value of human papillomavirus deoxyribonucleic acid testing after conization in predicting residual cervical neoplasia. A strategy of managing patients with grade 3 cervical intraepithelial neoplasia, based on postconization human papillomavirus deoxyribonucleic acid findings and endocervical curettage results, is proposed.

Adult↗

The effects of the flow pattern on organic oxidation and nitrification in aerated submerged biofilters.

Previous research has shown that a submerged biofilter is effective in removing organic matter and total organic nitrogen. Upflow and downflow biofilters were set up to investigate the different oxidative efficiencies on organic matter and ammonia nitrogen of different biofilter positions and to compare the biological activities of the upflow and downflow patterns. A comparison of the operational characteristics of the two types of biofilters is discussed. The main COD removal zone is 0-20 cm in the upflow biofilter, but in the downflow biofilter it occurs in the submerged zone. The nitrification process is dependent on the HRT and the residual COD. In the downflow biofilter, the efficiency of the nitrification increases with the HRT. The growth of nitrifying bacteria has a tendency to take place in higher zones in the downflow biofilter, especially for a longer HRT. Batch tests measured the biological activity of heterotrophs and nitrifying autotrophs with decomposition rates. In the upflow biofilter, the nitrification rates increased while the COD oxidative rates decreased with the height of the biofilter, so the effect of the HRT on the activity of the nitrifying autotrophs is significant. However, in the down biofilter, the activity of the nitrifying autotrophs was similar at different heights in the same HRT runs with the maximum nitrifying autotrophs activity being at an HRT of 6 hours.

Bacteria↗

Natural frequency analysis of periodontal conditions in human anterior teeth.

The purpose of this study was to evaluate the possibility of using natural frequency (NF) analysis to detect the attachment loss of periodontal tissue. In this study, 698 anterior teeth were examined by a conventional probing method and also by NF analysis. The teeth were triggered to vibrate with an impulse hammer, and the vibrational response was detected by an acoustic sensor. Our results demonstrate no significant difference in NF values between the upper-lower/left-right quadrants of the tested teeth, although the mean natural frequency value of central incisors with periodontal disease was found to be 1.24 +/- 0.11 kHz which is significantly lower than that of teeth in a healthy condition (1.34 +/- 0.20kHz; p < 0.01). On the other hand, the mean frequency for periodontal disease involving canines (1.28 +/- 0.09 kHz) was also significantly lower than the corresponding value for healthy analogs (1.35 +/- 0.17 kHz; p < 0.05). These results suggest that NF analysis appears to be an effective method for assessing the periodontal condition of anterior teeth. Moreover, since this method is noninvasive, nondestructive, and necessitates minimal tooth contact, it can serve as an effective method for the early quantifiable testing and prevention of periodontal disease.

Adult↗