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Biomedical subjects

C T Chen

Publications and source records attributed to C T Chen.

At least 109 records · Page 6Linked to original sources
PubMed1998

Expression of annexin II in human middle ear cholesteatoma.

Annexin II has previously been discovered to have involvements in DNA replication and metabolism, bone resorption, and osteoclast formation. In our work, Western blotting and immunohistostaining studies revealed the presence of annexin II in human cholesteatoma tissue. With monoclonal mouse antiannexin II antibody, a 36,000 dalton protein (annexin II) was identified in the cholesteatoma protein extract. Immunoalkaline-phosphatase staining selectively localized annexin II to the keratinocytes in the basal and spinous layers of the cholesteatoma tissue. In normal human skin, annexin II is expressed mainly in the cytoplasmic membrane of its keratinocytes in the basal layer without significant staining in its nucleus. However, annexin II is expressed in both the cytoplasmic membrane and the nucleus of the keratinocytes in basal and spinous layers of human cholesteatomas. Our findings indicate a possible physiologic role of annexin II in keratinocyte cell hyperproliferation during development of human cholesteatoma.

Adult↗
PubMed1998

Autofluorescence in normal and malignant human oral tissues and in DMBA-induced hamster buccal pouch carcinogenesis.

Light-induced fluorescence spectroscopy was conducted on human oral malignant and normal tissues. Under 330-nm excitation wavelength, significant differences in fluorescence intensity were observed around 380- and 460-nm emission. Furthermore, 7,12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis in hamster buccal pouch was investigated to elucidate whether similar alterations of fluorescence spectroscopy occurred during the development of squamous cell carcinoma. Similar to the spectral profiles of human oral malignant and normal tissues, the most intense fluorescence peaks in the pouches occurred at 380 nm and 460 nm emission under 330 nm excitation wavelength. At 380 nm emission, the fluorescence intensity of normal pouch mucosa was stronger than those of DMBA-treated abnormal tissues at different stages of carcinogenesis. However, at 460 nm emission, the fluorescence intensity of DMBA-treated tissues was not only stronger than that of normal pouch mucosa but also shifted to 470 nm. These results suggest that under 330 nm excitation wavelength fluorescence spectroscopy may be useful for the detection of oral malignant lesions.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

Image restoration and reconstruction with a Bayesian approach.

We have extended Johnson's Bayesian method for image restoration and reconstruction by introducing diagonal line sites, using symmetric neighborhood configurations, and employing an additional hyperparameter for estimation of line sites. A general formulation for arbitrary neighborhood configurations was derived. The major part of this paper deals with the conduct of computer simulations intended to examine the effect of the hyperparameters, the diagonal line sites, and the size of the neighborhood configuration on the performance of the proposed Bayesian method. We show that, for optimal performance, distinct hyperparameters should be used for the intensity sites and line sites. The results also suggest that a large neighborhood configuration should be used. By comparing the near-optimal restored images, we demonstrated that the use of diagonal line sites, along with the symmetric configurations thus made possible, can effectively remove the blocky edge artifacts and produce images of better quality. When the method was applied to positron emission tomography (PET) image reconstruction, our results showed that the quality of the reconstructed images was improved for both computer-simulated and real patient PET data.

Algorithms↗
PubMed1998

Contracture of the deltoid muscle: imaging findings in 17 patients.

OBJECTIVE: A retrospective review of the MR images and radiographs of 26 shoulders in 17 patients suffering from contracture of the deltoid muscle was used to establish the characteristic imaging findings. MATERIALS AND METHODS: Deltoid muscle contractures in 26 shoulders in 17 patients encountered over a 4-year period are reported. The history of intramuscular injection and clinical symptoms and signs are detailed. Imaging studies including routine radiographs (24 shoulders), MR images (25 shoulders), and computed arthrotomograms (two shoulders) were reviewed. On MR images, the winging angle of the scapula (angle between the axis of the scapular body and the coronal plane of the chest) and the diameter of the lesion were measured and compared with data derived from 24 age-matched control subjects. RESULTS: Diagnostic MR features of deltoid muscle contracture include fibrotic cord in the deltoid muscle, especially its middle portion, extending from the superior acromial surface to the deltoid tuberosity, and winging of the scapula (increased winging angle of the scapula). Characteristic radiographic features include abduction contracture, winging of the scapula, lateral down-sloping of the acromial process, and a superior acromial enthesophyte. CONCLUSION: MR images are sensitive and accurate in the diagnosis of contracture of the deltoid muscles. Characteristic features also allow accurate routine diagnosis on radiographs.

Arm↗
PubMed1998

Comparison of the cuffed oropharyngeal airway and laryngeal mask airway in spontaneous breathing anesthesia.

BACKGROUND: The cuffed oropharyngeal airway (COPA) is a modified Guedel airway with a cuff at its distal end and a standard 15 mm connector at its proximal end. This study was performed to determine if the COPA would offer any advantage over the laryngeal mask airway (LMA). METHODS: Eighty ASA class I to II adult patients scheduled for short elective procedures (less than 1 h) were randomly allocated into two groups. All patients were given atropine 0.01 mg/kg, fentanyl 2 micrograms/kg and propofol 2 mg/kg intravenously for induction of anesthesia. The COPA or LMA was inserted following the loss of eyelash reflex. If the jaw was not relaxed enough for insertion of a COPA or LMA, succinylcholine 1 mg/kg was given to facilitate the insertion. When correctly positioned, the cuff was immediately inflated with an appropriate volume. Gentle positive pressure ventilation was applied before spontaneous breathing resumed. Capnography was used to assess the patency of the airway. Anesthesia was maintained with isoflurane-N2O-O2 until the end of surgery. The success rate, vital signs, and adverse events were evaluated and compared. RESULTS: The success rate in the LMA group (95%) was higher than the COPA group (85%). The increase in circulatory response after the LMA insertion was greater than that after the COPA insertion (P < 0.05). Nine patients (22.5%) in the LMA group needed succinylcholine to facilitate insertion compared with only two patients (5%) in the COPA group. Additional manipulation was frequently (57.5%) needed after inserting the COPA to maintain the patency of the airways, but none needed so in the LMA group. Two patients had laryngospasms upon removal of the LMA, but none had laryngospasm in the COPA group. The incidence of sore throat in the LMA group was higher than in the COPA group (18% vs. 10%). CONCLUSIONS: We demonstrated that the COPA could be easily inserted without the need of muscle relaxants in most patients. But the COPA needed airway intervention to provide an effective airway in most patients. Compared with the LMA, the COPA caused less stimulation than the LMA.

Adult↗
PubMed1998

Pharmacodynamics of doxorubicin in human prostate tumors.

The pharmacodynamics of doxorubicin in human prostate tumors were studied using histocultures of radical prostatectomy specimens. Drug treatment lasted 96 h. The antiproliferative effect was measured by the inhibition of DNA precursor ([3H]thymidine) incorporation, and the cytotoxic effect was measured by monitoring cells with fragmented DNA, as indicated by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. The average [3H]thymidine labeling index in 17 tumors was 39% (range, 20-56%). The antiproliferative and cytotoxic effects were concentration dependent and reached 100% at 6 and 17 microM doxorubicin. The cytotoxic concentrations were significantly higher than the antiproliferative concentrations, indicating that prostate tumors were more sensitive to the antiproliferative effect than they were to the cytotoxic effect of doxorubicin. The antiproliferative effect was inversely correlated with patient's age (P < 0.02) and weakly correlated with LI and Gleason grade (P = 0.07 and 0.06, respectively), but it was not correlated with clinical stage, prostate-specific antigen secretion, or race of patients (P > 0.12). In contrast, the cytotoxic effect was positively correlated with Gleason grade (P < 0.05) and weakly correlated with stage (P < 0.08), but it was not correlated with the other parameters (P > 0.18). The opposite correlations between the two effects with tumor grade suggest that the two effects are not coupled. A comparison of the drug concentrations required to produce 50% antiproliferative (0.06 microM) and cytotoxic (2 microM) effects and the literature data on plasma drug concentrations derived from systemic treatment suggest that there are minimal drug effects at the clinically achievable drug concentrations and that regional delivery of doxorubicin to the prostate may be necessary to provide adequate concentrations to produce antiproliferative and cytotoxic effects.

Adenocarcinoma↗
PubMed1998

Immunoglobulin D multiple myeloma: a case report.

Immunoglobulin D (IgD) multiple myeloma is a rare disorder with a poor prognosis. We herein report a case of IgD myeloma presenting with renal failure and bicytopenia. A bone marrow biopsy specimen showed infiltration of homogeneous plasma cells, which stained positively for IgD and light chains. We review the literature and discuss the clinical manifestations, diagnosis and treatment strategy for this rare tumor.

Adult↗
PubMed1997

Massive intratumor hemorrhage in facial plexiform neurofibroma.

BACKGROUND: Plexiform neurofibromatosis is a feature of von Recklinghausen's disease. Head and neck lesions may produce varying degrees of cosmetic and functional deformity. However, life-threatening hemorrhage into facial plexiform neurofibromas has not been previously reported. METHOD: We report two patients with von Recklinghausen's disease who experienced massive hemorrhage into facial neurofibromas, one following a blunt injury and the other without a known initiating event. RESULTS: Conservative management did not stop the hemorrhage into facial neurofibromas in either instance. Surgical exploration was mandated for hemorrhage control and evacuation of blood clots. Hemostasis was attained by a combination of hypotensive anesthesia and chromic catgut suture ligatures. CONCLUSIONS: These case reports demonstrate a potentially lethal complication in patients with facial plexiform neurofibroma. Where a competent and experienced interventional neuroradiologist is not available, surgical exploration should be undertaken to control bleeding.

Adolescent↗
PubMed1997

Automated registration of ventilation-perfusion images with digital chest radiographs.

RATIONALE AND OBJECTIVES: The authors have developed an automated computerized technique for registering radionuclide lung scan images with digital chest radiographs. METHODS: Threshold analysis was used to construct contours around the high-activity regions of radionuclide ventilation-perfusion images. Analogous contours were constructed around the lung regions of the corresponding digitized radiographs. Contour dimensions and anatomic landmark locations were then used to superimpose the radiographic, ventilation, and perfusion images. RESULTS: Evaluation of 25 sets of images indicated that the scheme provided adequate to excellent registration in 91% of the pairwise combinations. CONCLUSION: This automated scheme for registering ventilation-perfusion images with digital chest radiographs has the potential to aid radiologists in the interpretation of these images.

Adult↗
PubMed1997

A glucose-sensing polymer.

We have prepared a robust polymer that can be used to measure glucose concentrations in complex biological media. At alkaline pH, the metal-complexing polymer binds glucose and instantly releases protons in proportion to the glucose concentration over a clinically relevant range (0 to 25 mM). The inexpensive polymer is sufficiently selective to provide an easily measurable response to glucose in porcine plasma. The polymer's ability to function at nonphysiological pH (at which the buffer capacity of biological samples is small) makes it possible to design simple and inexpensive sensing devices based on measurement of changes in proton concentration.

Animals↗
PubMed1997

Maxillary myxoma treated with wide resection and immediate reconstruction: a case report.

Myxoma of the jaw is a rare, benign bone tumor of odontogenic origin. Given the locally aggressive nature of the myxoma and the high rate of recurrence, there is a tendency to choose radical resection of the jaw segment containing the tumor mass as the treatment modality. As they appear to attain a considerable size prior to diagnosis because of their insidious growth characteristics, particularly in the maxilla, treatment requiring a hemimaxillectomy often results in a significant functional and aesthetic disability. This is particularly distressing as this condition usually affects the young. We present the case of a 16-year-old female who suffered a large maxillary myxoma with swelling of the left cheek for 2 years. Wide resection of the tumor tissue including the maxillary medial and lateral buttresses and part of the hard palate with preservation of maxillary alveolar bone and teeth was undertaken, and the maxillary buttresses were reconstructed with autogenous rib grafts. At the 3.5-year follow-up there was no local recurrence and no tooth loss. Both the functional result and aesthetic contour proved satisfactory. Wide resection with preservation of vital structures and simultaneous autogenous bone graft reconstruction is our preferred method. A long-term follow-up is needed.

Adolescent↗
PubMed1997

Full intrusion of a tooth after facial trauma.

We report two cases of fully intruded tooth after facial fracture in adults. In the first case, the lateral incisor was intruded into the nasal cavity and slipped into the pyriform sinus during operation. The second case involved full intrusion of a molar into the maxillary sinus, resulting in infection. The importance of a thorough intraoral examination for patients with facial trauma is emphasized. All missing teeth should be accounted for to ensure that they have not dislodged inside the body. When full intrusion of a tooth is suspected, facial computed tomography scan may provide assistance with definite diagnosis. If an incisor is completely intruded into the nasal cavity, removal through the floor of the nostril should be considered.

Accidents, Traffic↗
PubMed1997

Adaptive control of arterial blood pressure with a learning controller based on multilayer neural networks.

We discuss a two-model multilayer neural network controller for adaptive control of mean arterial blood pressure (MABP) using sodium nitroprusside. A model with an autoregressive moving average (ARMA), representing the dynamics of the system, and a modified back-propagation training algorithm are used to design the control system to meet specified objectives of design (settling time and undershoot/overshoot) and clinical constraints. The controller is associated with a weighting-determinant unit (WDU) to determine and update the output weighting factor of the parallel two-model neural network for adequate control action and a control-signal modification unit (CMU) to comply with clinical constraints and to suppress the effect of adverse noise and to improve the WDU performance. Extensive computer simulations indicate satisfactory performance and robustness of the proposed controller in the presence of much noise, over the full range of plant parameters, uncertainties, and large variations of parameters.

Adaptation, Physiological↗
PubMed1997

Small simulated polyps in pig colon: sensitivity of CT virtual colography.

PURPOSE: The authors evaluated computed tomographic (CT) virtual colography for the detection of simulated polyps under ideal conditions, as well as the effects on lesion conspicuity of (a) collimation, (b) table pitch, and (c) orientation of the colon lumen with respect to the gantry. MATERIALS AND METHODS: Pig colon was resected and cleansed, and polyps with diameters of 3, 7, and 10 mm were created. Each specimen was scanned with collimation of 5 and 7 mm and table pitch of 1.0, 1.6, and 2.0 at angles of 0 degrees, 45 degrees, and 90 degrees to the gantry. The initial two-dimensional (2D) images were reconstructed at 1-mm intervals (2D reconstructions), from which three-dimensional (3D) virtual colography images were generated. Polyp conspicuity on the initial and reconstructed 2D images and the 3D reconstructions was evaluated on a three-point scale: 0 = polyp not depicted, 1 = polyp faintly depicted, and 2 = polyp clearly depicted. RESULTS: The 10-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image and 3D reconstruction without regard to collimation, table pitch, or angle to the gantry. The 7-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image, but conspicuity on 3D reconstructions varied as the imaging parameters varied. The 3-mm-diameter polyp was faintly depicted (grade 1 conspicuity) on the initial and reconstructed 2D images and 3D reconstructions, but conspicuity varied on the 3D reconstructions as the imaging parameters varied. CONCLUSION: CT virtual colography helped detection of small mucosal polyps regardless of the angle of the colon lumen to the gantry at which they were obtained.

Animals↗
PubMed1997

Light-induced fluorescence spectroscopy to differentiate benign and malignant uterine cervical lesions.

In Taiwan, cervical cancer is the leading malignancy among women. For the early detection of cervical neoplasia, light-induced fluorescence spectroscopy was conducted ex vivo to assess the ability of this technique to differentiate cervical neoplastic tissue (20 samples) from normal or inflammatory cervical tissue (37 samples) at an excitation wavelength of 280 nm. The principal fluorescent peaks occurred within +/- 5 nm of 330 nm and 470 nm emission. At 330 nm emission, the spectrum of the normal or inflammatory tissue was significantly stronger than that of the neoplastic tissue after are normalization. However, at 470 nm emission, the spectrum of the normal or inflammatory tissue was significantly weaker than that of the neoplastic tissue. A diagnostic algorithm based on the ratio of relative intensities of 330 nm to 470 nm emission within the 5 +/- nm peak area of each sample was calculated and paired. The ratios showed that histologically neoplastic lesions could be distinguished from inflammatory samples using a 280-nm-excitation wavelength with a sensitivity, specificity and positive predictive value of 94%, 82% and 73%, respectively. The average ratio of malignant or dysplastic cervical samples was significantly greater than that of the inflammatory samples (p < 0.001). Our ex vivo study indicated that light-induced fluorescence spectroscopy may be useful in differentiating malignant or premalignant from normal or inflammatory cervical tissue.

Algorithms↗
PubMed1996

Two-dimensional protein crystallization via metal-ion coordination by naturally occurring surface histidines.

A powerful and potentially general approach to the targeting and crystallization of proteins on lipid interfaces through coordination of surface histidine residues to lipid-chelated divalent metal ions is presented. This approach, which should be applicable to the crystallization of a wide range of naturally occurring or engineered proteins, is illustrated here by the crystallization of streptavidin on a monolayer of an iminodiacetate-Cu(II) lipid spread at the air-water interface. This method allows control of the protein orientation at interfaces, which is significant for the facile production of highly ordered protein arrays and for electron density mapping in structural analysis of two-dimensional crystals. Binding of native streptavidin to the iminodiacetate-Cu lipids occurs via His-87, located on the protein surface near the biotin binding pocket. The two-dimensional streptavidin crystals show a previously undescribed microscopic shape that differs from that of crystals formed beneath biotinylated lipids.

Bacterial Proteins↗