Biomedical subjects

Chia-Hung Chang

Publications and source records attributed to Chia-Hung Chang.

7 recordsLinked to original sources

PubMed2006

VNTRDB: a bacterial variable number tandem repeat locus database.

Variable number tandem repeat-PCR (VNTR-PCR) is a novel method developed for molecular typing of microorganisms. This method has proven useful in epidemiological studies in medical microbiology. Although hundreds of bacterial genomes have been sequenced, variable number tandem repeats (TRs) derived from comparative genome analyses are scarce. This may hamper their application to the surveillance of bacteria in molecular epidemiology. Here, we present a freely accessible variable number tandem repeat database (VNTRDB) that is intended to be a resource for helping in the discovery of putatively polymorphic tandem repeat loci and to aid with assay design by providing the flanking sequences that can be used in subsequent PCR primer design. In order to reveal possible polymorphism, each TR locus was obtained by comparing the sequences between different sets of bacterial genera, species or strains. Through this comparison, TRs which are unique to a genus can also be identified. Moreover, a visualization tool is provided to ensure that the copy number and locus length of repeats are correct. The VNTRDB is available at http://vntr.csie.ntu.edu.tw/.

Bacteria↗

PubMed2006

A study of grid artifacts formation and elimination in computed radiographic images.

Computed radiography (CR) has many advantages such as filmless operations, efficiency, and convenience. Furthermore, it is easier to integrate with the picture archiving and communication systems. Another important advantage is that CR images generally have a wider dynamic range than conventional screen film. Unfortunately, grid artifacts and moiré pattern artifacts may be present in CR images. These artifacts become a more serious problem when viewing CR images on a computer monitor when a clinic grade monitor is not available. Images produced using a grid with higher frequency or a Potter--Bucky grid (i.e., a moving grid, Bucky for short) can reduce occurrence but cannot guarantee elimination of these artifacts [CR & PACS (2000); Detrick F (2001), pp 7-8]. In this paper, the formation of the artifacts is studied. We show that the grid artifacts occur in a narrow band of frequency in the frequency domain. The frequency can be determined, accurately located, and thus removed from the frequency domain. When comparing the results obtained from the proposed method against the results obtained using previous computer methods, we show that our method can achieve better image quality.

Artifacts↗

PubMed2006

Myocardial infarction masked by high level spinal anesthesia in a patient undergoing herniorrhaphy.

Myocardial infarction (MI) is one of the leading causes of perioperative morbidity. Although evidence to prove significant reduction of perioperative MI with regional anesthesia is lacking, anesthesiologists still prefer this technique over general anesthesia for surgery involving the lower abdomen or lower extremities, especially in patients with cardiac risks. However, high level of sensory block during spinal anesthesia may obscure the referred pain from MI, which could contribute to the delay of diagnosis and treatment of an acute perioperative attack. We report a case of MI which occurred either intraoperatively or postoperatively, with symptoms that were masked by high level of sensory block to T4 by spinal anesthesia. This perioperative MI was only diagnosed when the patient recovered from anesthesia in the post-anesthesia care unit (PACU).

Aged↗

PubMed2005

Sudden hearing loss after general anesthesia--a case report.

Hearing impairment following many types of neuraxial anesthetic techniques has alreadly been reported previously. However, postoperative sudden hearing loss after general anesthesia (excluding cardiopulmonary bypass cases) for nonotologic surgery is rarely reported. We present a 42-year-old female patient, who underwent ophthalmologic surgery under general anesthesia because of diabetic retinopathy and developed postoperative hearing loss of the left ear. Sensorineural hearing loss was diagnosed and it has persisted without improvement for 2 years following surgery.

Adult↗

PubMed2005

The effects of continuous axillary brachial plexus block with ropivacaine infusion on skin temperature and survival of crushed fingers after microsurgical replantation.

BACKGROUND: Continuous axillary brachial plexus block with local anesthetic has been shown to improve tissue perfusion after replantation surgery of the extremity. The present study aimed to investigate whether continuous axillary brachial plexus block with ropivacaine infusion can improve the survival of the reconstructive fingers secondary to an increase in its skin temperature in patients receiving replantation surgery of the crushed fingers. METHODS: Under general anesthesia, 18 patients received replantation or toe-to-hand transplantation of their crushed digits. They were randomly divided into two groups. Under ultrasound guidance, continuous axillary brachial plexus analgesia was effected by a loading dose of 10 ml 0.75% ropivacaine, followed by an infusion of 4-5 ml per hour for up to three days (Group A). Patients who did not receive continuous analgesia postoperatively served as a control (Group B). An infrared thermometer was used to hourly assess the skin temperature of the surgical and non-surgical sites in both groups for 24 h after the surgery. In addition, the survival (the rate of re-operation or amputation) of the reconstructive digits was also evaluated in both groups. RESULTS: The skin temperature of the digits (T1) on both groups did not show any significant difference at any point of time after the surgery albeit there was a trend of increased skin temperature on the reconstructive digits in patients receiving continuous axillary brachial plexus block (Group A) as compared to those without receiving the block (Group B). Also, the difference in skin temperature (dT) differed slightly at 0, 9 and 21 hours postoperatively in Group A in comparison with Group B (0.75 +/- 0.65 vs. -2.33 +/- 1.24, 0.53 +/- 0.34 vs. -3.02 +/- 1.27, -0.125 +/- 0.55 vs. -2.33 +/- 0.91, p < 0.05). However, no patients in both groups received a second operation or amputation of the graft. CONCLUSIONS: The result of this study demonstrated that axillary brachial plexus block with continuous infusion of 0.75% ropivacaine can increase the skin temperature, an index of tissue perfusion, of the reconstructive digits for 24 h after microvascular surgery of the crushed fingers. However, graft survival was good in both groups.

Adult↗

PubMed2004

Anesthetic management of Boerhaave's syndrome.

Boerhaave's syndrome or spontaneous esophageal perforation is a life threatening condition which demands early diagnosis and urgent management. Although very selective patients can be treated nonoperatively, in most patients, better overall results can only be attained with early aggressive surgery. Clinical data and accounts of anesthetic management of this condition scarely appear in medical literature. Managing these patients for surgery is among the most challenging tasks facing the anesthesiologist because they may develop septic syndrome with shock. A rapid-sequence induction is mandatory, and the procedures that may aggravate the injury to esophagus should be avoided. Inotropic support and close attention to fluid balance may be required during operation. Because Boerhaave's syndrome is rare, we report here two cases to illustrate possible anesthetic implications of this disease. Both patients underwent thoracotomy to relieve empyema of mediastinum under general anesthesia. The first patient recovered completely after operation due to early diagnosis and treatment, but the second patient developed multiple organ failure and died after operation due to delayed diagnosis of esophageal rupture and severe sepsis. Because survival is directly related to the time to diagnosis and treatment, all clinicians need to be aware of this lethal disease.

Anesthesia↗

PubMed2004

High satisfaction with problem-based learning for anesthesia.

BACKGROUND: The aim of this study was to compare students' satisfaction between problem-based learning (PBL) and lecture-based traditional teaching of anesthesia. METHODS: One hundred and thirty-seven fifth-year medical students were enrolled in a course which used a hybrid curriculum for teaching about anesthesia. The hybrid curriculum included 9 essential lectures and 3 related PBL case discussions. A Linkert 5-point scale was used for to assess students' satisfaction levels between PBL and lecture-based traditional teaching. Data were collected through a year-end questionnaire over 2 academic years from 2002 to 2003. Scores regarding the satisfaction levels between these 2 teaching methods were analyzed using a 2-sided paired t-test. RESULTS: Most students preferred PBL over the lecture-based traditional teaching in the following 6 aspects: learning about anesthesia, understanding other medical knowledge, being interested in and motivated to learn, training for future work, training of personal abilities, and being confident and satisfied with the teaching method (p < 0.05). However, traditional teaching was superior to PBL in enhancing the speed of learning with greater understanding of a basic knowledge of anesthesia, as well as in providing more solid content with understanding of a greater number of anesthetic techniques (p < 0.05). Satisfaction levels with this curriculum did not generally differ between students enrolled in different classes in 2002 and 2003. CONCLUSIONS: Although the assessment tools and content of PBL need to be modified, implementation of PBL for teaching anesthesia showed satisfactory results.

Anesthesiology↗