Biomedical subjects
Publications and source records attributed to C Y Chen.
We observed that weakly and strongly rubbed polyvinyl-cinnamate surfaces align liquid crystal films perpendicular and parallel to the rubbing direction, respectively. Surface-specific sum-frequency vibrational spectroscopy was used to probe molecular orientations and alignments of the rubbed surfaces and provide a molecular-level understanding of the observation.
In this paper, we study the effects on G-protein activation of a non-uniform distribution of signalling components. The spatial heterogeneity is attributed to caveolae, a specific membrane microdomain which has been observed to redistribute and concentrate signalling molecules. Diffusive coagulation-fragmentation equations are used to describe the aggregation of caveolin homo-oligomers and the subsequent formation of caveolae. A system of reaction-diffusion equation is thus formulated and, in order to describe the restrictions imposed by caveolae on the movement of receptors and G-protein, a segregation coefficient is introduced which serves to regulate the preference of the species to segregate according to the concentration of caveolae. The results demonstrate that the heterogeneous distribution of the signalling components and the efficiency of G-protein activation can vary significantly, depending on the concentration of caveolae.
Photooxidation of azo dye Reactive Black 5 (RB5) by H202 was performed with a novel supported iron oxide in a batch reactor in the range of pH 2.5-6.0. The iron oxide was prepared through a fluidized-bed reactor (FBR) and much cheaper than the Nafion-based catalysts. Experimental results indicate that the iron oxide can significantly accelerate the degradation of RB5 under the irradiation of UVA light (wavelength = 365 nm). An advantage of the catalyst is its long-term stability, which was confirmed through using the catalyst for multiple runs in the degradation of RB5. In addition, this study focused mainly on determining the proportions of homogeneous catalysis and heterogeneous catalysis in the batch reactor. Conclusively, although heterogeneous catalysis contributes primarily to the oxidation of RB5 during pH 4.5-6.0, the homogeneous catalysis is of increasing importance below pH 4.0 because of the Fe ions leaching from the catalyst to solution.
We present a 75-year-old man who, for 2 weeks, had progressive pain in both of his thighs when standing straight. MR imaging showed a sequestrated disk fragment, which had a signal intensity similar to that of a herniated disk with a rim enhancement in the posterior epidural space and a ruptured outermost annulus of the intervertebral disk at L2-3. Awareness of these MR imaging findings can help in the diagnosis of posterior epidural disk migration.
Using oncoplastic surgical techniques for breast preservation, breast surgeons can achieve widened surgical margins at the same time that the shape and appearance of the breast is preserved and sometimes rejuvenated. Oncoplastic surgical resection is designed to follow the cancer's contour, which generally follows the segmental anatomy of the breast, which has been well understood since the mid 19th century because of pioneering anatomic studies performed by Sir Astley Paston Cooper. The quadrantectomy, developed by Veronesi and colleagues in the 1970's, follows these same anatomic principles of wide segmental resection. The more surgically narrow lumpectomy as popularized in the U.S. uses a smaller, scoop-like non-anatomic resection of cancer. With negative surgical margins, the lumpectomy is equivalent to the quadrantectomy in achieving the goals of breast conservation as measured by local recurrence and survival. However, the lumpectomy is less versatile for resection of larger cancers, and can be more prone to creating suboptimal cosmetic defects. Cancers with large in situ components can be particularly problematic for resection with the standard lumpectomy, when they extend both centrally toward the nipple and peripherally to distal terminal ductulo-lobular units, which typically occur in a pie-shaped segmental distribution. Ductal segments, each of which ultimately drains to a single major lactiferous sinus at the nipple, vary in size and depth in the breast. Breast surgeons should carefully evaluate the cancer distribution and extent in the breast before operation. A combination of imaging methods (mammography with magnification views, ultrasonography, magnetic resonance imaging [MRI], or all) may yield the best estimates of overall tumor extent. Multiple bracketing wires afford the greater help to complete surgical excision. Those tumors with segmental spreading are best excised by oncoplastic resections according to their distribution.
A novel activated alumina-supported iron oxide-composite (denoted as FeAA-500) was prepared by so-called fluidized-bed reactor (FBR) crystallization. X-ray powder diffraction (XRD), N2 adsorption/desorption, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to characterize the FeAA-500. The photo-catalytic activity of the FeAA-500 was evaluated in the photooxidative degradation of 0.1 mM azo-dye reactive black 5 (RB5) in the presence of H2O2 and UVA light (lambda = 365 nm) in a solution with a pH of 2.5. Complete decolorization of the model pollutant RB5 was achieved; the total organic carbon (TOC) removal ratio was 95%, and a trace amount of leached ferric ion was detected following 75 min of reaction when 2.0 g/L FeAA-500 was used as a catalyst. FeAA-500 has high photo-catalytic activity; it is therefore a promising heterogeneous photocatalysis of the degradation of organic compounds.
This study investigated Fenton and Fenton-like reactions at low iron concentration (<or==10 mg l-1) to oxidize three commercial azo dyes, namely Red MX-5B, Reactive Black 5 and Orange G. In some local cases in Taiwan, wastewater color was found to be the only problem in meeting local effluent standards. This investigation reveals that both of these methods can remove the color of these dyes completely. Moreover they only produce little sludge in wastewater that meet local effluent standards and do not need to further treat. The effects of Fe2+, Fe3+, H2O2 and solution pH on dye decolorization are demonstrated in detail. The optimum pH for both Fenton and Fenton-like reactions in this study are about pH 2.5-3.0. Increasing the dose of ferric nitrate enhances the dye decolorization. The optimal levels of H2O2 required for the process are also examined. High levels of H2O2 appear to reduce dye decolorization. In addition, it is also found that decolorization of azo dyes undergoes a faster reaction rate than mineralization of azo dyes.
AIMS: To clarify the incidence of pre-tracheal lymph node metastasis in squamous cell carcinoma of the esophagus, and their impact on survival. METHODS: A cohort of 101 patients with squamous cell carcinoma of the thoracic esophagus who underwent esophagectomy together with 2-field lymphadenectomy including the pre-tracheal region was analysed, retrospectively. The p-TNM staging included stage I in 9, stage IIa in 33, stage IIb in 4, stage III in 43, and stage IV in 12 cases. RESULTS: Nodal metastases were identified in 56 patients (55.4%). Subcarinal lymph node and pre-tracheal lymph-node metastases were found in 24 patients (23.8%) and 15 patients (14.9%), respectively. The 5-year cumulative survival rates were 26.5 and 2.5% in nodal negative and nodal positive patients, respectively. Patients with pre-tracheal nodal metastasis all died within 2 years. Cox proportional hazards model in patients with nodal involvement revealed T-factor (p=0.0017), pre-tracheal nodal involvement (p=0.0055) and distant metastasis (p=0.0024) as independent prognostic factors. CONCLUSIONS: Our findings suggest that pre-tracheal lymph node metastasis indicates a dismal prognosis. Its occurrence is not unusual, especially in tumour of upper or middle thoracic esophagus. The subcarinal node cannot be regarded as a sentinel node of the pre-tracheal nodal station. Complete lymphadenectomy excluding the pre-tracheal lymph nodes in treating esophageal cancers is only a myth.
Bacterial infection stimulates nitric oxide (NO) production in chondrocytes. However, the role of NO in chondrocyte apoptosis after infection remains unclear. The purpose of the study was to test if inhibition of NO could ameliorate apoptosis and modulate matrix protein gene expression in bacteria-infected chondrocytes. It was shown that pre-treating chondrocytes with L-NAME (1 mM) significantly decreased the release of NO (from 72 to 14 microM) and the extent of apoptosis (from 52.9% to 18.9%). Pre-treatment with L-NAME also counteracted the bacteria-induced downregulation of Type II collagen (from 26% to 79%) and aggrecan (from 63% to 105%) mRNA levels. Inhibition of NO after the induction of infection could not decrease the extent of apoptosis and modulate matrix protein gene expression. The results of this study support the hypothesis that NO has an important role in bacteria-induced chondrocyte apoptosis. Pre-treatment but not post-treatment could ameliorate the extent of apoptosis and reestablish the cartilage matrix protein gene expression. This study suggests that in addition to NO, other mechanisms may be responsible for the sustained destruction of articular cartilage in the post-infectious arthropathy.
After an analysis of 3,441 radical hysterectomies performed in our department, we found, after modification of the operative technique in 1983, the more lateral the excision the less the recurrence rate. The recurrence rate for Stage 1b-2a and Stage 2b patients comparing the years before 1983 to the years after decreased to 12.4% from 15.7% (158/1,006 vs 268/2,163; p = 0.009) in Stage 1b-2a and 24.6% from 55.8% (38/68 vs 47/191; p = 0.0007) in Stage 2b, respectively. With the modern trend of aspiring for an easier lifestyle, most physicians practice earlier. Therefore only very few physicians study radical hysterectomy. As the skill of surgery needs a longer period of education and training, it may only interest physicians who work with medical professionals as part of a team at a medical center. In the future, we should provide gynecological residents not only with a training program using the classic textbooks, but also with different points of view on changes and developments in radical hysterectomy. We hope to promote an attitude of offering patients access to different choices and opportunities of therapy. Radical hysterectomy is in fact a treatment option for patients with bulky cervical lesions and Stage 2b in particular.
A 46-year-old woman complained of persistent abnormal vaginal bleeding over ten days. Her intrauterine device had been removed two years before. Soon after, she suffered from menorrhagia and metrorrhagia. An incidental finding of severe anemia was also noted. In this admission, our initial T2-weighted magnetic resonance imaging (MRI) revealed a well-demarcated mass predominantly in the uterine cavity. The mass was depicted by an isointense signal relative to the myometrium on T1-weighted images, high signal intensity on T2-weighted images, and slightly heterogeneous enhancement on post-contrast images. The patient refused surgery. After two years, follow-up MRI showed a pedunculated mass protruding into the upper third of the vagina with a stalk connecting to the posterior wall of the uterine cavity, simulating submucosal myoma. Histological diagnosis was compatible with low-grade endometrial stromal sarcoma.
The epidemiology pattern of varicella appears to vary among regions with different climates, population densities, and degrees of development. This study investigated the age-specific varicella zoster virus (VZV) seroprevalence in children aged 0 to 12 years in Taiwan and compared these seroprevalences between free and private vaccination areas. Residual sera were collected from 13 hospitals with 1,401 valid samples. Immunoglobulin G antibodies to VZV were measured by enzyme-linked immunosorbent assay. Parents of 656 children answered questions about the varicella incidence and varicella vaccination history of their children. In the 8-12 year-olds, the seroprevance ranged between 88.0-93.8% in northern, central, and eastern, while it was only 76.1% in southern Taiwan. The seroprevalence of children 0-5 years old were significantly different between free and private vaccination areas. Seropositive children who reported no history of varicella or receiving varicella vaccine accounted for 26.1-59.3% of the total positive cases. Our findings suggest the possible effects of climate, geographical conditions, and lifestyle on the seroepidemiology of VZV in Taiwan. The efforts of implementing a varicella vaccination program in Taiwan should focus on reaching high levels of coverage.
To test the hypothesis that intrapulmonary perfluorochemical (PFC) liquid may induce hypothermia, and to compare the effects of internal (IC), external (EC), and combined cooling techniques (EC + IC), 14 juvenile rabbits were randomized to EC by a cold blanket (4 degrees C, n = 5), IC by intrapulmonary cold PFC liquid lavage (4 degrees C, n = 5), or combined IC with PFC and EC (n = 4). Arterial blood gas, blood pressure, and lung mechanics were monitored, and lung histology was examined by light microscopy. The results showed that cooling rates and the time needed to be cooled down to 30 degrees C were significantly faster in EC and EC + IC than IC (p < 0.05). Blood gas analysis and cardiopulmonary function were within the normal range in all groups. Histological assessment revealed varied atelectasis in all lung regions in EC, whereas PFC-filled lungs (IC and EC + IC) demonstrated more homogenous expansion and no evidence of atelectasis. The results indicate that intrapulmonary PFC may be an effective technique to induce and/or augment hypothermia while supporting gas exchange, lung volume and pulmonary architecture.
Understanding how cell growth is regulated in response to environmental signals remains a challenging biological problem. Recent studies indicate the TOR (target of rapamycin) kinase acts within an intracellular regulatory network used by eukaryotic cells to regulate their growth according to nutrient availability. This network affects all aspects of gene expression, including transcription, translation, and protein stability, making TOR an excellent candidate as a global regulator of cellular activity. Here we review our recent studies of two specific transcriptional outputs controlled by TOR in the budding yeast, S. cerevisiae: (1) positive regulation of genes involved in ribosome biogenesis, and (2) negative regulation of genes required for de novo biosynthesis of glutamate and glutamine. These studies have raised the important issue as to how diverse nutritional cues can pass through a common signaling pathway and yet ultimately generate distinct transcriptional responses.
The purpose of this randomised, double-blind, double-dummy, parallel-group study was to evaluate the efficacy and tolerability of telmisartan 40 mg once daily vs. enalapril 10 mg once daily in 147 Taiwanese patients with mild-to-moderate essential hypertension (diastolic blood pressure [DBP] 90-109 mmHg). After 6 weeks' treatment, telmisartan produced a significantly greater reduction from baseline in the primary endpoint of trough seated DBP compared with enalapril 10 mg (11.7 vs. 8.7 mmHg, respectively; p = 0.02). Numerically greater reductions compared with baseline in seated systolic blood pressure (SBP), standing DBP, and standing SBP were achieved with telmisartan compared with enalapril. Also, numerically greater proportions of patients achieved blood pressure control (DBP/systolic blood pressure [SBP] <90/140 mmHg) and responded to treatment (reduction from baseline in trough seated DBP > or = 10 mmHg and/or post-treatment DBP <90 mmHg; reduction from baseline in trough seated SBP > or = 10 mmHg and/or post-treatment SBP <140 mmHg) with telmisartan 40 mg compared with enalapril 10 mg. Although both treatments were well tolerated, the incidence of cough was markedly lower with telmisartan 40 mg (8.5%) than with enalapril 10 mg (18.4%) in this population of Taiwanese hypertensive patients.
Ocular herpes simplex virus (HSV) infection is generally accepted to be a unilateral disease and simultaneous bilateral recurrent ocular HSV disease is uncommon. Recurrent ocular herpes was generally thought to be characterized by corneal involvement. We here report an 11-year-old boy with monthly bilateral recurrent HSV type 1 blepharitis for more than 10 years. He had a general normal immunological examination. Only supportive or topical acyclovir ointment treatment proved adequate for controlling the monthly recurrent disease without corneal involvement or other sequelae to date. The case highlights the unusual presentation, general normal immune function, clinical course and treatment opinion for recurrent HSV blepharitis.
A mathematical model is constructed to study promiscuous coupling of receptors to G-proteins and to simulate events leading to the activation of multiple effector pathways within a cell. The model is directed at a better understanding of the factors that determine the efficacy and potency of a drug. Assuming that the receptors can exist in multiple conformational states, and allowing for agonist specific conformation, a system of ordinary differential equations is constructed and subsequently pathway-dependent agonist efficacy and potency order is predicted. A simple case of the compartmentalization of receptors and G-proteins is also given, using the current model to illustrate the effects of spatial heterogeneity on the predicted response.
We present the implementation of a short-tip tapping-mode tuning fork near-field scanning optical microscope. Tapping frequency dependences of the piezoelectric signal amplitudes for a bare tuning fork fixed on the ceramic plate, a short-tip tapping-mode tuning fork scheme and an ordinary tapping-mode tuning fork configuration with an 80-cm optical fibre attached are demonstrated and compared. Our experimental results show that this new short-tip tapping-mode tuning fork scheme provides a stable and high Q factor at the tapping frequency of the tuning fork and will be very helpful when long optical fibre probes have to be used in an experiment. Both collection and excitation modes of short-tip tapping-mode tuning fork near-field scanning optical microscope are applied to study the near-field optical properties of a single-mode telecommunication optical fibre and a green InGaN/GaN multiquantum well light-emitting diode.