Biomedical subjects

Chia-Ling Tsai

Publications and source records attributed to Chia-Ling Tsai.

8 recordsLinked to original sources

PubMed2005

Inhibition of corneal angiogenesis by local application of vasostatin.

PURPOSE: This study was designed to investigate the effects of the locally supplied endogenous angiogenesis inhibitor vasostatin (VS) on corneal angiogenesis. METHODS: Recombinant VS was expressed and purified. The effects of VS on the proliferation of endothelial cells were investigated using the methyl thiazolyl tetrazolium (MTT) assay in the absence or presence of angiogenic factors such as basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF). Corneal neovascularization was induced by implantation of hydron pellets containing bFGF in rat corneal micropockets. The potency of VS to inhibit corneal angiogenesis was investigated by incorporation of VS with bFGF in hydron pellets or topical application of VS containing eye drops to rat eyes implanted with bFGF pellets. The extent of corneal neovascularization was evaluated by microscopic and histological analyses. RESULTS: VS potently inhibited the growth of endothelial cells in the absence or presence of angiogenic factors such as bFGF or VEGF. In the rat corneal micropocket assay, concurrent incorporation of VS abolished the bFGF induced neovascularization. When formulated in a methylcellulose eye drop, VS remained intact and functional in a 4 degrees C solution for more than 7 days. Topical application of VS eye drops potently inhibited bFGF induced neovascularization in rat corneas. CONCLUSIONS: The present study effectively demonstrated the potential feasibility of local application of VS for treatment of corneal angiogenesis.

Administration, Topical↗

PubMed2005

Accurate image registration for quadrature tomographic microscopy.

This paper presents a robust and fully automated registration algorithm for registration of images of Quadrature Tomographic Microscopy (QTM), which is an optical interferometer. The need for registration of such images is to recognize distinguishing features of viable embryos to advance the technique for In Vitro Fertilization. QTM images a sample (live embryo) multiple times with different hardware configurations, each in turn producing 4 images taken by 4 CCD cameras simultaneously. Embryo movement is often present between imaging. Our algorithm handles camera calibration of multiple cameras using a variant of ICP, and elimination of embryo movement using a hybrid of feature- and intensity-based methods. The algorithm is tested on 20 live mouse embryos containing various cell numbers between 8 and 26. No failure thus far, and the average alignment error is 0.09 pixels, corresponding to the range of 639 and 675 nanometers.

Algorithms↗

PubMed2004

Model-based method for improving the accuracy and repeatability of estimating vascular bifurcations and crossovers from retinal fundus images.

A model-based algorithm, termed exclusion region and position refinement (ERPR), is presented for improving the accuracy and repeatability of estimating the locations where vascular structures branch and cross over, in the context of human retinal images. The goal is two fold. First, accurate morphometry of branching and crossover points (landmarks) in neuronal/vascular structure is important to several areas of biology and medicine. Second, these points are valuable as landmarks for image registration, so improved accuracy and repeatability in estimating their locations and signatures leads to more reliable image registration for applications such as change detection and mosaicing. The ERPR algorithm is shown to reduce the median location error from 2.04 pixels down to 1.1 pixels, while improving the median spread (a measure of repeatability) from 2.09 pixels down to 1.05 pixels. Errors in estimating vessel orientations were similarly reduced from 7.2 degrees down to 3.8 degrees.

Algorithms↗

PubMed2003

A view-based approach to registration: theory and application to vascular image registration.

This paper presents an approach to registration centered on the notion of a view--a combination of an image resolution, a transformation model, an image region over which the model currently applies, and a set of image primitives from this region. The registration process is divided into three stages: initialization, automatic view generation, and estimation. For a given initial estimate, the latter two alternate until convergence; several initial estimates may be explored. The estimation process uses a novel generalization of the Iterative Closest Point (ICP) technique that simultaneously considers multiple correspondences for each point. View-based registration is applied successfully to alignment of vascular and neuronal images in 2-d and 3-d using similarity, affine, and quadratic transformations.

Algorithms↗

PubMed2003

The dual-bootstrap iterative closest point algorithm with application to retinal image registration.

Motivated by the problem of retinal image registration, this paper introduces and analyzes a new registration algorithm called Dual-Bootstrap Iterative Closest Point (Dual-Bootstrap ICP). The approach is to start from one or more initial, low-order estimates that are only accurate in small image regions, called bootstrap regions. In each bootstrap region, the algorithm iteratively: 1) refines the transformation estimate using constraints only from within the bootstrap region; 2) expands the bootstrap region; and 3) tests to see if a higher order transformation model can be used, stopping when the region expands to cover the overlap between images. Steps 1): and 3), the bootstrap steps, are governed by the covariance matrix of the estimated transformation. Estimation refinement [Step 2)] uses a novel robust version of the ICP algorithm. In registering retinal image pairs, Dual-Bootstrap ICP is initialized by automatically matching individual vascular landmarks, and it aligns images based on detected blood vessel centerlines. The resulting quadratic transformations are accurate to less than a pixel. On tests involving approximately 6000 image pairs, it successfully registered 99.5% of the pairs containing at least one common landmark, and 100% of the pairs containing at least one common landmark and at least 35% image overlap.

Algorithms↗

PubMed2003

Dentinogenesis imperfecta associated with osteogenesis imperfecta: report of two cases.

Osteogenesis imperfecta (OI) is a heritable systemic disorder of the connective tissue. Dentinogenesis imperfecta (DI), which is sometimes an accompanying symptom of OI, belongs to a group of genetically conditioned dentin dysplasias and is characterized clinically by an opalescent amber appearance of the dentin. Although the teeth of DI cases wear more easily and excessively compared to normal teeth, they do not appear to be more susceptible to dental caries than normal teeth. Two cases of DI associated with OI are presented in this paper, with 1 case suffering from nursing bottle caries. The purposes of this paper are to present the dental and skeletal characteristics of moderately and mildly involved DI associated with OI, and to discuss the possible methods of dental treatment. Patients with OI and opalescent teeth should be evaluated as soon as the deciduous teeth erupt; immediate dental involvement and oral hygiene instruction can be of help in reducing the necessity of extensive dental care.

Child↗

PubMedDate not supplied

In vitro acid resistance of CO2 and Nd-YAG laser-treated human tooth enamel.

The purposes of this study were to test the effectiveness of laser treatment (pulsed CO(2) and pulsed Nd-YAG) on in vitro acid resistance of human enamel. Thirty enamel surfaces were prepared from 10 extracted permanent premolars (3 surfaces per tooth). Two experimental surfaces on each tooth were irradiated with either CO(2) or Nd-YAG lasers. All specimens were demineralized in 10 ml lactate buffer for 24 or 72 h after laser treatment. After 24-hour acid treatment the mean concentration of calcium that dissolved into the lactate buffer in the CO(2) laser group was significantly less than in the control group, while the dissolved calcium concentration in the Nd-YAG laser group did not differ from the control group (p > 0.05). The erosion depth in the CO(2) laser group was significantly shallower than in the Nd-YAG laser group (p < 0.001). After 72-hour acid treatment, the acid resistances of neither group of laser-treated surfaces differed significantly from the controls. By scanning electron microscopy, the acid-eroded laser-treated enamel surfaces had type I and type II etching patterns, fissures, and disordered rough surfaces compared to control enamel, with a regular type II etching pattern. CO(2) laser-treated tooth enamel was more resistant to acid challenge than was Nd-YAG laser-treated enamel, given the same fluence, but neither type of laser increased acid resistance of subsurface enamel.

Acids↗

PubMedDate not supplied

A retrospective study of dental treatment under general anesthesia of children with or without a chronic illness and/or a disability.

BACKGROUND: The indications for dental treatment under general anesthesia have been described by various authors as extensive decay, behavioral management problems, a medically compromised patient, a handicapped patient, and a combination of these. Few studies have been undertaken to identify the range of treatment provided for chronically sick children. The aim of this study was to identify the characteristics of dental procedures performed under general anesthesia on children with a chronic illness and/or a disability, and compare these findings with other normal children. METHODS: A retrospective, comparative study was designed. Children who received comprehensive dental treatment under general anesthesia at Kaohsiung Chang-Gung Memorial Hospital, Taiwan, in 2002 were enrolled in this study. Patients with a chronic illness and/or a disability were included in group I, and other relatively normal patients were placed in group II. RESULTS: Group I children were significantly older than those of group II (p < 0.0001). Different patterns of dental treatment were noted when the 2 groups were compared. Significantly greater numbers of stainless steel crown build-ups (p = 0.028) and pulpal treatments (p = 0.003) were found among group II patients. There was no significant between-group difference in restorations (p = 0.934); however, group I had a significantly higher (p = 0.006) number of extractions. CONCLUSIONS: By comparing the different patient groups receiving comprehensive dental treatment under general anesthesia, it was found that patients with a chronic illness and/or a disability had a significantly higher average surgical age and fewer pulpal treatments, received fewer stainless steel crowns, and underwent more extractions. Providing early treatment for children with a chronic illness and/or a disability may improve their dental health and maintain full dentition so as to reduce the number of subsequent tooth extractions. Thus, it is highly recommended to refer these children at an earlier age to a hospital where tooth restoration under general anesthesia can be performed.

Anesthesia, General↗