Biomedical subjects

H-S Chang

Publications and source records attributed to H-S Chang.

6 recordsLinked to original sources

PubMed2006

Analysis of colonoscopic findings in the differential diagnosis between intestinal tuberculosis and Crohn's disease.

BACKGROUND AND STUDY AIMS: Intestinal tuberculosis and Crohn's disease are chronic inflammatory bowel disorders that are difficult to differentiate from one another. This study aimed to evaluate the diagnostic value of various colonoscopic findings in the differential diagnosis between intestinal tuberculosis and Crohn's disease. PATIENTS AND METHODS: Colonoscopic findings on initial work-up were prospectively recorded in patients with an initial diagnosis of either intestinal tuberculosis or Crohn's disease. These findings were analyzed after a final diagnosis of intestinal tuberculosis (n = 44) or Crohn's disease (n = 44) had been made after follow-up. RESULTS: Four parameters (anorectal lesions, longitudinal ulcers, aphthous ulcers, and cobblestone appearance) were significantly more common in patients with Crohn's disease than in patients with intestinal tuberculosis. Four other parameters (involvement of fewer than four segments, a patulous ileocecal valve, transverse ulcers, and scars or pseudopolyps) were observed more frequently in patients with intestinal tuberculosis than in patients with Crohn's disease. We hypothesized that a diagnosis of Crohn's disease could be made when the number of parameters characteristic of Crohn's disease was higher than the number of parameters characteristic of intestinal tuberculosis, and vice versa. Making these assumptions, we calculated that the diagnosis of either intestinal tuberculosis or Crohn's disease would have been made made correctly in 77 of our 88 patients (87.5 %), incorrectly in seven patients (8.0 %), and would not have been made in four patients (4.5 %). CONCLUSIONS: A systematic analysis of colonoscopic findings is very useful in the differential diagnosis between intestinal tuberculosis and Crohn's disease.

Adolescent↗

PubMed2005

Postmortem study of the spinal cord showing snake-eyes appearance due to damage by ossification of the posterior longitudinal ligament and kyphotic deformity.

UNLABELLED: CLINICAL DESIGN: A case report. OBJECTIVES: To elucidate the clinical role of snake-eyes appearance in this case, correlation between radiological, clinical and postmortem study was performed. SETTING: Aichi, Japan. CASE REPORT: A 73-year-old man developed weakness and pain in the upper limbs due to kyphotic deformity secondary to laminectomy for cervical ossification of the posterior longitudinal ligament. Axial magnetic resonance imaging revealed snake-eyes appearance from C4 to C6. He died of acute myocardial infarction 3 months after anterior decompressive surgery. RESULTS: A postmortem examination of the cervical spinal cord showed small cystic six necrotic areas at the junction of the central gray matter and the ventrolateral posterior column, one in the right and one in the left, in association with neuronal loss in the anterior horn. CONCLUSIONS: Bilateral small intramedullary high-signal areas known as 'snake-eyes appearance' located around the central gray matter and the ventrolateral posterior column, are associated with neuronal loss in the compressed anterior horn that played an important role in worsening weakness of the upper limbs.

Aged↗

PubMed2004

Automatic classification of interference patterns in driven event series: application to single sympathetic neuron discharge forced by mechanical ventilation.

This study proposes a method for the automatic classification of nonlinear interactions between a strictly periodical event series modelling the activity of an exogenous oscillator working at a fixed and well-known rate and an event series modelling the activity of a self-sustained oscillator forced by the exogenous one. The method is based on a combination of several well-known tools (probability density function of the cyclic relative phase, probability density function of the count of forced events per forcing cycle, conditional entropy of the cyclic relative phase sequence and a surrogate data approach). Classification is reached via a sequence of easily applicable decision rules, thus rendering classification virtually user-independent and fully reproducible. The method classifies four types of dynamics: full uncoupling, quasiperiodicity, phase locking and aperiodicity. In the case of phase locking, the coupling ratio (i.e. n: m) and the strength of the coupling are calculated. The method, validated on simulations of simple and complex phase-locking dynamics corrupted by different levels of noise, is applied to data derived from one anesthetized and artificially ventilated rat to classify the nonlinear interactions between mechanical ventilation and: (1) the discharges of two (contemporaneously recorded) single postganglionic sympathetic neurons innervating the caudal ventral artery in the tail and (2) arterial blood pressure. Under central apnea, the activity of the underlying sympathetic oscillators is perturbed by means of five different lung inflation rates (0.58, 0.64, 0.76, 0.95, 1.99 Hz). While ventilation and arterial pressure are fully uncoupled, ventilation is capable of phase locking sympathetic discharges, thus producing 40% of phase-locked patterns (one case of 2:5, 1:1, 3:2 and 2:2) and 40% of aperiodic dynamics. In the case of phase-locked patterns, the coupling strength is low, thus demonstrating that this pattern is sliding. Non-stationary interactions are observed in 20% of cases. The two discharges behave differently, suggesting the presence of a population of sympathetic oscillators working at different frequencies.

Adrenergic Fibers↗

PubMed2004

Morphology and properties of denture acrylic resins cured by microwave energy and conventional water bath.

OBJECTIVES: This study examined the influence of microwave energy levels on the morphology and properties of an impact resistant denture material poly(methyl methacrylate) with a thickness of 10 mm. METHODS: A microwave flask containing two resin blocks was processed at 80, 160, 240, and 560 W for 15, 10, 7, and 2 min, separately. Each Flask was then turned over, and cured for an additional 2 min at 560 W. The process using conventional methods was carried out at 70 degrees C for 9 h. The blocks were tested for hardness, porosity, flexural properties, solubility, and molecular weight. The morphology of the specimens after staining with osmium tetroxide was examined by transmission electron microscope. RESULTS: The changes in temperature with time were recorded during microwave heating at 80, 160, and 240 W, respectively. A significantly large difference in the curing temperature was observed when comparing these two processing methods. There was little difference in the mean values of surface hardness and the weight percent of the insoluble parts. The mean domain size and the volume fraction of the rubber phase favor of the water-bath method. However, the porosity in the water-bath-cured specimens was much less than that in the microwave-cured specimens. Thus, the conventionally cured specimens showed better flexural strength and flexural modulus than the microwave-cured specimens. SIGNIFICANCE: This study has shown that microwave energy can efficiently polymerize denture base polymer. Highly statistical differences in morphology and flexural properties favor of the water-bath method. Choice of a suitable microwave power and polymerization time is important in order to reduce porosity to a minimum level and increase the domain size and volume of the rubber phase.

Acrylic Resins↗

PubMed2004

Atypical endoscopic features of rectal carcinoids.

BACKGROUND AND STUDY AIMS: It is not normally difficult to diagnose carcinoid tumors (well-differentiated endocrine neoplasms) of the rectum endoscopically, as they usually have a characteristic appearance. However, little is known about the atypical endoscopic findings in some rectal carcinoids and the present study was performed to analyze these. PATIENTS AND METHODS: The endoscopic findings in 67 consecutive patients with rectal carcinoids (37 men, 30 women; age range 23 - 76) were analyzed retrospectively. RESULTS: Tumor size ranged from 2 mm to 30 mm (average 7.4 mm). Of the 67 patients, 52 (78 %) displayed the characteristic endoscopic findings of smooth, round, sessile elevations covered with normal-appearing or yellow-discolored mucosa; in 15 (22 %) there were one or more atypical endoscopic findings. These included a semipedunculated appearance (n = 6), hyperemia (n = 5), a central depression (n = 6), erosion (n = 5), and ulceration (n = 4). Atypical findings were noted in none of 20 carcinoids &lambda< 5 mm in diameter; in six (20 %) of the 30 carcinoids between 5 mm and 9 mm; in six (43 %) of the 14 carcinoids between 10 mm and 19 mm; and in three (100 %) of the three carcinoids >/= 20 mm in diameter ( P < 0.001). Invasion into the muscularis propria or metastasis to the liver or lymph nodes occurred in three of the four patients with ulceration, but it was confirmed in only one of the 63 patients without ulceration ( P < 0.001). CONCLUSIONS: Atypical endoscopic appearances of rectal carcinoids are observed more frequently as the size of the tumor increases and a finding of ulceration may have a prognostic value.

Adult↗

PubMed2004

Melanotic neuroectodermal tumour of infancy in the maxilla: a case report.

A 4.5-month-old Chinese boy presented with a bulging mass in the anterior right maxillary region. Clinical features and incisional biopsy examination confirmed the diagnosis of melanotic neuroectodermal tumour of infancy (MNTI). The lesion had first been noted a month before the biopsy. The extent of the lesion was defined via computed tomography, and surgical excision was accomplished through a partial maxillectomy under general anaesthesia. The patient has been irregularly followed-up over the past 8 years, and no evidence of recurrence has been found, either by clinical examination or serial computed tomography scans. A bony defect and a lack of alveolar process were noted on the right side of the anterior maxilla. The patient displayed social withdrawal at school as a result of his partial anodontia. There have only been a limited number of reports on the dental rehabilitation of postoperative MNTI. We report a case of maxillary MNTI in which the need for dental rehabilitation was emphasized.

Biopsy↗