Biomedical subjects

S L Chen

Publications and source records attributed to S L Chen.

At least 55 records · Page 3Linked to original sources

PubMed2000

Complications and recommended practices for electrosurgery in laparoscopy.

BACKGROUND: Electrosurgery is one of the most commonly used energy systems in laparoscopic surgery. Two major categories of potential complications related to electrosurgery in laparoscopy are mechanical trauma and electrothermal injury. The latter can result from unrecognized energy transfer in the operational field or, less commonly, to unnoticed stray current outside the laparoscopic field of view. Stray current can result from insulation failure, direct coupling, or capacitive coupling. METHODS: We reviewed the literature concerning essential biophysics of electrosurgery, including electrosurgical waveform differentiation, tissue effect, and variables that determine tissue effect. The incidence of electrosurgical injuries and possible mechanisms responsible for the injuries are discussed. Different types of injuries may result in different clinical manifestations and histopathological findings. Gross and microscopic pathological check-ups of the injury sites may distinguish between different mechanisms, and thus provide further clues postoperatively. RESULTS: Several recommended practices are proposed to avoid electrosurgical injury laparoscopically. To achieve electrosurgical safety and to prevent electrosurgical injuries, the surgical team should have a good understanding of the biophysics of electrosurgery, the basis of equipment and general tissue effects, as well as the surgeon's spatial orientation and hand-eye coordination. Some intraoperative adjuvant procedures and newly developed safety devices have become available may aid to improve electrosurgical safety. CONCLUSIONS: Knowledge of the biophysics of electrosurgery and the mechanisms of electrosurgical injury is important in recognizing potential complications of electrosurgery in laparoscopy. Procedures for prevention, intraoperative adjuvant maneuvers, early recognition of the injury with in-time salvage treatment, and alertness to postoperative warning signs can help reduce such complications.

Burns, Electric↗

PubMed2000

The NOD Idd9 genetic interval influences the pathogenicity of insulitis and contains molecular variants of Cd30, Tnfr2, and Cd137.

Previous analyses of NOD mice have shown that some genes control the development of both insulitis and diabetes, while other loci influence diabetes without reducing insulitis. Evidence for the existence of a gene only influencing diabetes, Idd9 on mouse chromosome 4, is provided here by the development of a novel congenic mouse strain, NOD.B10 Idd9. NOD.B10 Idd9 mice display profound resistance to diabetes even though nearly all develop insulitis. Subcongenic analysis has demonstrated that alleles of at least three B10 genes, Idd9.1, Idd9.2, and Idd9.3 are required to produce Idd9-mediated diabetes resistance. Candidate genes with amino acid differences between the NOD and B10 strains have been localized to the 5.6 cM Idd9.2 interval (Tnfr2, Cd30) and to the 2.0 cM Idd9.3 interval (Cd137).

Alleles↗

PubMed2000

Low-dose whole-body irradiation (LD-WBI) changes protein expression of mouse thymocytes: effect of a LD-WBI-enhanced protein RIP10 on cell proliferation and spontaneous or radiation-induced thymocyte apoptosis.

Low-dose radiation (LDR) can potentiate cellular metabolic activities or immune functions in vivo (hormesis), and can render cells resistant to DNA or chromosome damage caused by subsequent high-dose radiation (adaptive response). Protein synthesis was required for these cellular responses to LDR. In the present study, the early expression of proteins by thymocytes in response to low-dose whole-body irradiation (LD-WBI) was investigated. The expression of novel and previously existing proteins was found in the nucleus, cytoplasm, and extracellular fluid of thymocytes at 4 hours after WBI with 75-mGy X-rays. A 10 kD protein (RIP10) was seen in the cytoplasm of thymocytes after LD-WBI was further investigated. The fraction containing RIP10 separated by Sephadex G 100 gel filtration potentiated spontaneous thymocyte, and mitogen-induced splenocyte proliferation. Western blotting demonstrated that an anti-RIP10 antibody could react with a 10-kD cytoplasm protein and also with a 13-kD nuclear protein in thymocytes at 4 h after LD-WBI. Immunocytochemical staining showed the existence of RIP10 in several immune tissues including thymus, spleen, and lymph node. RIP10 expression, as determined by immunocytochemical staining and flow cytometry, was enhanced at 4-8 h after LD-WBI. Cell-cycle arrest (G(0)/G(1) block with decreased percentage of S-phase cells), and increased levels of spontaneous or radiation-induced apoptosis were observed in thymocytes incubated with RIP10 antibody in vitro for 4 h or 24 h. These results directly demonstrated the role of RIP10 in modulating cell proliferation and apoptosis. This finding is important to understand the mechanisms underlying LDR-induced hormesis and adaptive response.

Adaptation, Physiological↗

PubMed2000

The boomerang flap in managing injuries of the dorsum of the distal phalanx.

Finding an appropriate soft-tissue grafting material to close a wound located over the dorsum of a finger, especially the distal phalanx, can be a difficult task. The boomerang flap mobilized from the dorsum of the proximal phalanx of an adjacent digit can be useful when applied as an island pedicle skin flap. The vascular supply to the skin flap is derived from the retrograde perfusion of the dorsal digital artery. Mobilization and lengthening of the vascular pedicle are achieved by dividing the distal end of the dorsal metacarpal artery at the bifurcation and incorporating two adjacent dorsal digital arteries into one. The boomerang flap was used in seven individuals with injuries involving the dorsal aspect of the distal phalanx over the past year. Skin defects in all patients were combined with bone,joint, or tendon exposure. The authors found that the flap was reliable and technically simple to design and execute. This one-step procedure preserves the proper palmar digital artery to the fingertip and has proven valuable for the coverage of wide and distal defects because it has the advantages of an extended skin paddle and a lengthened vascular pedicle. When conventional local flaps are inadequate, the boomerang flap should be considered for its reliability and low associated morbidity.

Arteries↗

PubMed2000

Induction of CD8 T cells by vaccination with recombinant adenovirus expressing human papillomavirus type 16 E5 gene reduces tumor growth.

The potential of the E5 protein as a tumor vaccine candidate has not been explored yet. In this study, we evaluate the human papillomavirus type 16 (HPV-16) E5 protein delivered by an adenovirus vector as a tumor vaccine for cervical lesions. The results demonstrate that a single intramuscular injection of a recombinant adenovirus carrying the HPV-16 E5 gene into syngeneic animals can reduce the growth of tumors which contain E5 gene expression. Moreover, the E5 vaccine-induced tumor protection occurs through CD8 T cells but not through CD4 T cells in in vitro assays. In addition, our studies using knockout mice with distinct T-cell deficiencies confirm that cytotoxic T-lymphocyte-induced tumor protection is CD8 dependent but CD4 independent. Hence, HPV-16 E5 can be regarded as a tumor rejection antigen.

Adenoviridae↗

PubMed2000

Recombinant adeno-associated virus expressing human papillomavirus type 16 E7 peptide DNA fused with heat shock protein DNA as a potential vaccine for cervical cancer.

In this study, we explore a potential vaccine for human papillomavirus (HPV)-induced tumors, using heat shock protein as an adjuvant, a peptide vaccine for safety, and adeno-associated virus (AAV) as a gene delivery vector. The tumor vaccine was devised by constructing a chimeric gene which contained HPV type 16 E7 cytotoxic T-lymphocyte (CTL) epitope DNA (M. C. Feltkamp, H. L. Smits, M. P. Vierboom, R. P. Minnaar, B. M. de Jongh, J. W. Drijfhout, J. ter Schegget, C. J. Melief, and W. M. Kast, Eur. J. Immunol. 23:2242-2249, 1993) fused with the heat shock protein gene as a tumor vaccine delivered via AAV. Our results demonstrate that this vaccine can eliminate tumor cells in syngeneic animals and induce CD4- and CD8-dependent CTL activity in vitro. Moreover, studies with knockout mice with distinct T-cell deficiencies confirm that CTL-induced tumor protection is CD4 and CD8 dependent. Taken together, the evidence indicates that this chimeric gene delivered by AAV has potential as a cervical cancer vaccine.

Animals↗

PubMed2000

Dangerous impact--commotio cordis.

Sudden death following blunt chest trauma is a frightening occurrence known as 'commotio cordis' or 'concussion of the heart'. It is speculated that commotio cordis could be caused by ventricular fibrillation secondary to an impact-induced energy that was transmitted via the chest wall to the myocardium during its vulnerable repolarization period. We describe a survivor of commotio cordis caused by a baseball. In this patient, an initial ventricular fibrillation was documented and converted by direct current defibrillation. Serial electrocardiographic changes (bifascicular conduction block and T wave inversion in precordial leads) were noticed in this patient. Our case suggested that coronary vasospasm might also play a role in commotio cordis.

Baseball↗

PubMed2000

Reliability and validity of a community needs assessment instrument for nursing homes in Taiwan.

Several studies have been conducted which identify the lack of nursing homes in the Taiwan area as a major problem. However, no research instruments were found which measure the perception of need for nursing homes. The purpose of this study was to evaluate the psychometric properties of a community needs assessment instrument for nursing homes in Taiwan, called the Perception Evaluation Tool (PET). A randomly selected sample of 319 subjects participated in the study. Results suggest the PET has appropriate reliability and validity.

Activities of Daily Living↗

PubMed1999

Role of APC in the selection of immunodominant T cell epitopes.

Following antigenic challenge, MHC-restricted T cell responses are directed against a few dominant antigenic epitopes. Here, evidence is provided demonstrating the importance of APC in modulating the hierarchy of MHC class II-restricted T cell responses. Biochemical analysis of class II:peptide complexes in B cells revealed the presentation of a hierarchy of peptides derived from the Ig self Ag. Functional studies of kappa peptide:class II complexes from these cells indicated that nearly 20-fold more of an immunodominant epitope derived from kappa L chains was bound to class II DR4 compared with a subdominant epitope from this same Ag. In vivo, T cell responses were preferentially directed against the dominant kappa epitope as shown using Ig-primed DR4 transgenic mice. The bias in kappa epitope presentation was not linked to differences in class II:kappa peptide-binding affinity or epitope editing by HLA-DM. Rather, changes in native Ag structure were found to disrupt presentation of the immunodominant but not the subdominant kappa epitope; Ag refolding restored kappa epitope presentation. Thus, Ag tertiary conformation along with processing reactions within APC contribute to the selective presentation of a hierarchy of epitopes by MHC class II molecules.

Amino Acid Sequence↗

PubMed1999

Simian virus 40 T antigen induces p53-independent apoptosis but does not suppress erbB2/neu gene expression in immortalized human epithelial cells.

Previously, we have shown that simian virus 40 (SV40) T antigen can directly cause apoptosis in immortalized human epithelial cells under normal growth conditions. In this study, we further characterized the mechanism of T-antigen-mediated apoptosis involving p53 and whether T antigen can suppress erbB2/neu gene expression. Our results show the differential regulation of erbB2/neu gene expression in different cell clones in response to T antigen transgene, indicating that the regression of erbB2/neu gene by SV40 T is cell-type dependent. Our previous study reported T-antigen-induced apoptosis in p53 mutant cells; however, in this study we find increased levels of p53 protein in T-antigen-containing cells. Therefore, we examined the transactivation function of p53 in these cells. Our data show the failure to transactivate p53, suggesting that increased p53 protein in T antigen expressing cells is functionless at least for transcriptional activation.

Antigens, Viral, Tumor↗

PubMed1999

Expression of mutant thyroid hormone nuclear receptors in human hepatocellular carcinoma cells.

To understand the expression and role of thyroid hormone nuclear receptors (TRs) in hepatocarcinogenesis, we characterized the TRs in 16 human hepatocellular carcinoma (HCC) specimens. The full-length cDNAs for the two TR subtypes, alpha1 and beta1, were cloned from several tumors by reverse transcription-polymerase chain reaction. Southern blot analysis indicated that, in addition to the full-length cDNA, truncated TRalpha1 and TRbeta1 cDNAs were present in nine tumors (53%). In addition, point mutations detected by the mismatch RNase cleavage assay in TRalpha1 and TRbeta1 were found in 65% and 76% of the tumors, respectively. The mutations were confirmed by DNA sequencing. Interestingly, most of the TRalpha1 mutations were in amino acid codons 209-228 and 245-256, two hot-spots in HCC patients. However, no hot-spot was detected in TRbeta1. The expression of TRalpha1 and TRbeta1 proteins was determined in the tissue extracts by western blotting. TRbeta1 protein was expressed or elevated in 10 tumors but not in normal livers, whereas the expression of TRalpha1 was variable among tumors. The mutant TR proteins were translated in vitro, and their hormone- and DNA-binding activities were evaluated. Abnormal binding to the thyroid hormone response elements was observed. The proteins' DNA binding activity was either partially impaired or completely lost. The high prevalence of TR mutations found in the tumors of patients with hepatocellular carcinoma suggests that mutant TRs could play an important role in liver carcinogenesis.

Adult↗

PubMed1999

The expression of type I growth factor receptors in the squamous neoplastic changes of uterine cervix.

AIM: The type I family of growth factor receptors includes ErbB1, ErbB2, ErbB3, and ErbB4 which are frequently overexpressed in various human cancer cells. In this study, we systematically investigated the frequency and distribution of these four receptors in relation to neoplastic changes and tumor behaviors in the uterine cervix. MATERIALS: A total 84 of cases including 12 cases of normal cervical tissues, 6 cases of low grade squamous intraepithelial lesion, 10 cases of high grade squamous intraepithelial lesion, and 56 cases of squamous cells carcinoma were examined. RESULTS: Our results show significant difference with increasing grades of dysplasia in terms of these four receptor expressions. No association was found between these four receptors and cell keratinization/differentiation of squamous cell carcinoma of the cervix. Of the four receptors studied, only the expression of erbB2/neu gene was significantly associated with lymph nodal metastasis. Moreover, we find that the coexpression of ErbB1 and ErbB4 was significant in cervical carcinoma. CONCLUSIONS: The coexpression of ErbB1 and ErbB4 in cervical carcinoma suggests that they may be involved in receptor heterodimerization leading to the activation of signaling pathway in the cervical carcinoma.

Carcinoma, Squamous Cell↗

PubMed1999

Pulmonary hypertension in systemic lupus erythematosus.

A prospective echocardiographic and clinical study was performed on 84 Chinese patients with systemic lupus erythematosus (SLE) and 99 controls to investigate the prevalence and the mechanism of pulmonary hypertension (PH) in SLE. Comparison between Doppler estimation and catheterization measurement was made in 12 cases to validate the predictive method. Compared to normal subjects, lupus patients had significantly increased systolic pulmonary artery pressure (SPAP) (29.59 +/- 12.52 vs 19.64 +/- 5.82, P < 0.001), mean pulmonary artery pressure (MPAP) (15.11 +/- 7.36 vs 10.21 +/- 4.72, P < 0.001) and total pulmonary resistance (TPR) (315.85 +/- 190.65 vs 220.37 +/- 55.92, P < 0.001). Nine of the 84 patients presented PH, defined as SPAP < 30 mmHg and MPAP > 20 mmHg. Pulmonary hypertensive patients had higher serum endothelin (ET) than non-pulmonary hypertensive patients, were more commonly in active stages, and presented Raynaud's phenomenon and rheumatoid factors. ET level was correlated with echocardiographic pulmonary pressure. Pulmonary hypertension commonly occurs in Chinese patients with SLE (11%), and it correlates with the lupus activity and the elevation of serum endothelin.

Adolescent↗

PubMed1999

Effect of ethanol on the activity and conformation of Penaeus penicillatus acid phosphatase.

The effect of ethanol on the activity of Penaeus penicillatus acid phosphatase has been studied. The results show that ethanol significantly inhibits enzyme activity as a non-competitive inhibitor, with Ki 8.75%. The conformational changes of the enzyme molecule induced by ethanol were followed using fluorescence emission, ultraviolet difference and circular dichroism (CD) spectra. Increasing the ethanol concentration caused the fluorescence emission intensity of the enzyme to increase. The ultraviolet difference spectra of the enzyme denatured with ethanol had two negative peaks at 220 and 278 nm, and a positive peak at 240 nm. Increasing the ethanol concentration produced a small shoulder peak at 287 nm in addition to the increases in the negative magnitudes of the 220 and 278 nm peaks. The changes of the fluorescence and ultraviolet difference spectra reflected the changes of the microenvironments of the tryptophan and tyrosine residues of the enzyme. The CD spectrum changes of the enzyme show that the secondary structure of the enzyme also changed. The results suggest that ethanol is a non-competitive inhibitor and the conformational integrity of the enzyme is essential for its activity.

Acid Phosphatase↗

PubMed1999

Weight satisfaction and dieting practices among college males in Taiwan.

OBJECTIVE: To obtain baseline data regarding body mass index (BMI), weight satisfaction and weight perception in male college students. Approaches used to lose weight and characteristics of dieters were also investigated. METHODS: Written questionnaires and height and weight measurements were used to collect data. Nine-hundred thirty male college students selected by multiple stage sampling among colleges in Taiwan participated in this study. Simple frequency and ANOVA were used to analyze data. Post hoc analyses were performed with the LSD test when the F ratio for the ANOVA was significant at p<0.05. RESULTS: The mean BMI for all subjects was 21.7. Males with a BMI < or =22.5 are considered thin by Taiwanese and world standards. Yet 34% of these males were attempting to lose weight and 14% percent perceived themselves as either overweight or obese. Exercise was the main approach to losing weight for subjects in all weight categories. Subjects in the dissatisfied/dieting group tended to measure body weight more frequently (p<0.05), spent more time exercising and reading nutrition information (p<0.05) and skipped breakfast and lunch more frequently (p<0.05) than non-dieters. Male dieters ate fewer vegetables and less meat than non-dieters. CONCLUSIONS: Male college students had frequent misconceptions and dissatisfaction with their body weight. Behavioral characteristics among those dissatisfied with their weight indicate they are at risk for developing eating disorders.

Adult↗

PubMed1999

Disease-inducible transgene expression from a recombinant adeno-associated virus vector in a rat arthritis model.

Rheumatoid arthritis (RA) is a systemic autoimmune disease affecting 1% of the world's population, with significant morbidity and mortality. In this study, we investigated a recombinant adeno-associated virus (rAAV) vector for its potential application in RA gene therapy. rAAV encoding Escherichia coli beta-galactosidase was injected into rat joints which had already been induced into acute arthritis after local lipopolysaccharide (LPS) administration, and the efficiency of in vivo transduction was evaluated. We observed a striking correlation between vector transgene expression and disease severity in arthritic joints. The inflammatory reaction peaked at 3 to 7 days after LPS treatment, and, at the same time, 95% of the synoviocytes had high-level transgene expression. Gene expression diminished to the basal level (5%) when the inflammation subsided at 30 days after LPS treatment. More importantly, the diminished transgene expression could be efficiently reactivated by a repeated insult. The transgene expression in normal joints transduced with rAAV remained low for a long period of time (30 days) but could still be induced to high levels (95%) at 3 to 7 days after LPS treatment. This is the first demonstration of disease state-regulated transgene expression. These findings strongly support the feasibility of therapeutic as well as preventative gene transfer approaches for RA with rAAV vectors containing therapeutic genes, which are expected to respond primarily to the disease state of the target tissue.

Animals↗

PubMed1999

Adenovirus-mediated p21((WAF1/SDII/CIP1)) gene transfer induces apoptosis of human cervical cancer cell lines.

p21((WAF1/SDII/CIP1)) (p21) arrests cell growth by inhibiting cyclin-depend kinases. To explore the potential of using p21 for the gene therapy of cervical cancer, we infected human papillomavirus (HPV)-positive cervical cancer cells (HeLa, SiHa, and Z172) and HPV-negative cervical cancer cells (C33A) with recombinant adenovirus encoding p21 cDNA. The results revealed that effective inhibition of cell growth could be achieved by sense p21 adenovirus but not antisense p21 adenovirus infection and occurred through apoptosis as measured by DNA fragmentation and chromatin condensation. Apoptosis was also observed in xenografts of human cervical cancer cells infected with sense p21 adenovirus, as confirmed by in situ terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL). The apoptosis was not prevented by overexpression of the bcl-2 transgene. To sum up, the apoptotic effect suggests that p21 should be a tumoricidal agent instead of a tumoristatic agent in preventing cervical cancers. In addition, our report substantiates the combination of the high efficiency of adenovirus vector-mediated gene delivery and the apoptotic effect of p21.

Adenoviridae↗

PubMed1999

Dynamic counterbalance between direct and indirect vagal controls of atrioventricular conduction in cats.

The vagal system regulates the atrioventricular conduction time (TAV) via two opposing mechanisms: a direct effect on the atrioventricular node and an indirect effect through changes in heart period (TAA). To evaluate how dynamic vagal activation affects TAV, we stimulated the vagal nerve with frequency-modulated Gaussian white noise and estimated the transfer function from vagal stimulation to the TAV response under conditions of no pacing and constant pacing in anesthetized cats. The effect of changes in TAA on TAV was estimated by a random-pacing protocol. The transfer function from vagal stimulation to TAV has low-pass filter characteristics. Constant pacing increased the maximum step response in TAV (2.4 +/- 1.2 vs. 6.3 +/- 2.2 ms/Hz, P < 0.01). The time constant did not differ between the vagal effect on TAV and that on TAA (2.9 +/- 1.2 vs. 2.3 +/- 0.5 s). Because changes in TAA reciprocally affected TAV without significant delay, the direct and indirect effects were dynamically counterbalanced and exerted stable TAV transient response during vagal stimulation under normal sinus rhythm.

Acoustic Stimulation↗