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Biomedical subjects

C W Chang

Publications and source records attributed to C W Chang.

At least 37 records · Page 2Linked to original sources

Impact of a neuroscience intensive care unit on neurosurgical patient outcomes and cost of care: evidence-based support for an intensivist-directed specialty ICU model of care.

Analysis of patient data from a new neuroscience intensive care unit (NSICU) permitted evaluation of whether such a specialty ICU favorably altered clinical outcomes in critically ill neuroscience patients, and whether such a care model produced an efficient use of resources. A retrospective review was performed to compare (1) the clinical outcomes, as defined by percent mortality and disposition at discharge, between patients with a primary diagnosis of intracerebral hemorrhage treated in 1995 in medical or surgical ICUs and those treated in the same medical facility in an NSICU in 1997; and (2) the efficiency of care, as defined by length of ICU stay, total cost of care, and specific resource use, between patients treated in the NSICU and national benchmark standards for general ICUs during the 1997 fiscal year (FY). In the latter, extracted patient population data on neurosurgery patients requiring ICU treatment during FY 1997 were used with the following adjacent-disease related group (A-DRG)-coded diseases: craniotomy with and without coma or intracerebral hemorrhage, and skull fracture with and without coma lasting longer than 1 hour. Outcome measures of percent mortality and disposition at discharge in patients with intracerebral hemorrhage were significantly improved (P < .05), compared with those in a similar cohort treated 2 years earlier in a general ICU setting. Also, patients treated in the NSICU had shorter hospital stays (P < .01 ) and lower total costs of care (P < .01) than a national benchmark. The data suggest that a neuroscience specialty ICU arena staffed by specialty-trained intensivists and nurses is beneficial.

Aged↗

Exposure of workers to airborne microorganisms in open-air swine houses.

This study quantified the levels of airborne microorganisms in six swine farms with more than 10,000 pigs in subtropical Taiwan. We evaluated breeding, growing, and finishing stalls, which were primarily open-air buildings, as well as partially enclosed farrowing and nursery piggeries. Airborne culturable bacteria, gram-negative bacteria, and fungi were placed on appropriate media by using an all-glass impinger or single-stage Andersen microbial sampler. Results showed that mean concentrations of culturable bacteria and gram-negative bacteria were 3.3 x 10(5) and 143.7 CFU/m(3), respectively. The concentration of airborne culturable fungi was about 10(3) CFU/m(3), with Cladosporium the predominant genus. The highest airborne levels of culturable bacteria and gram-negative bacteria were identified in the finishing units. The air of the nursery stalls was the least contaminated with culturable and gram-negative bacteria. Irregular and infrequent cleaning, high pig density, no separation of wastes from pen floors, and accumulation of water as a result of the processes for cleaning and reducing pig temperature possibly compromise the benefits of the open characteristic of the finishing units with respect to airborne bacterial concentration.

Air Microbiology↗

Exposure assessment to airborne endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide in open style swine houses.

Information is limited for the exposure levels of airborne hazardous substances in swine feed buildings that are not completely enclosed. Open-style breeding, growing and finishing swine houses in six farms in subtropical Taiwan were studied for the airborne concentrations of endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide. The air in the farrowing and nursery stalls as partially enclosed was also simultaneously evaluated. Three selected gases and airborne dusts were quantified respectively by using Drager diffusion tubes and a filter-weighing method. Endotoxin was analyzed by the Limulus amoebocyte lysate assay. Average concentration of airborne total endotoxin among piggeries was between 36.8 and 298 EU/m(3), while that for respirable endotoxin was 14.1-129 EU/m(3). Mean concentration of total dust was between 0.15 and 0.34 mg/m(3), with average level of respirable dust of 0.14 mg/m(3). The respective concentrations of NH3, CO2 and H2S were less than 5 ppm, 600-895 ppm and less than 0.2 ppm. Airborne concentrations of total dust and endotoxin in the nursery house were higher than in the other types of swine houses. The finishing house presented the highest exposure risk to NH3, CO2 and H2S. Employees working in the finishing stalls were also exposed to the highest airborne levels of respirable endotoxin and dust. On the other hand, the air of the breeding units was the least contaminated in terms of airborne endotoxin, dust, NH3, CO2 and H2S. The airborne concentrations of substances measured in the present study were all lower than most of published studies conducted in mainly enclosed swine buildings. Distinct characteristics, including maintaining swine houses in an open status and frequent spraying water inside the stalls, significantly reduce accumulation of gases and airborne particulates.

Air Pollution, Indoor↗

Antibiotic treatment of orbital cellulitis: an analysis of pathogenic bacteria and bacterial susceptibility.

The proper choice of effective antibiotics is a mainstay for the treatment of orbital cellulitis. The lack of native data regarding the microorganism causing the infection and its antibiotic sensitivity prompted us to conduct this study. We retrospectively collected 29 cases of orbital cellulitis admitted to Chung-Ho Memorial Hospital of Kaohsiung Medical College from January 1994 to September 1998. The effectiveness of antibiotics with bacterial susceptibility was analyzed. Of the 29 cases, fifteen were male and fourteen female. The patients ranged in age from 7 months to 79 years (mean, 37.6 years). Sinusitis (9 cases, 31.0%) is the most common etiology. Fourteen cases received both medical and surgical treatments. Eighteen cases had purulent discharge from the infection areas sent for culture isolation of the microorganism. The culture positive rate was 50% (9 in 18 cases). The Staphylococcus aureus (5 cases) was the most common pathogen. The bacterial susceptibility test showed drug resistance of 100% for penicillin G (seven out of seven cases; 7/7), 100% for ampicillin (10/10), and 0% for amikacin (0/3) and vancomycin (0/7). Penicillin and ampicillin are not effective for those isolated bacteria. Oxacillin and gentamicin, frequently used in first line treatment, might encounter drug resistance in some cases. Amikacin and vancomycin, without any resistance in bacterial susceptibility tests, could be used in vision-threatening, critical, and intractable cases.

Adolescent↗

Robotic synthesis of 6-[18F]fluoro-L-dopa.

The aim of this study was to develop a method of semi-automated 6-[18F]fluoro-L-dopa (6-[18F]FDOPA) synthesis using a robotic system (Scanditronix Anatech RB III, Uppsala, Sweden). [18F]Fluorine was produced via 20Ne(d,alpha)18F using a Scanditronix MC17F cyclotron (Uppsala). The radiosynthesis was performed by the Scanditronix Anatech RB III robotic system. On average, a typical run produced 16-19 mCi of 6-[18F]FDOPA at end of synthesis (EOS) after 2 h irradiation of the F2/neon gas target. The total synthesis time was 110 min. The retention time of 6-[18F]FDOPA (the radio peak) was 8.2 min, which was consistent with the 6-[19F]FDOPA ultraviolet peak. The radiochemical purity was greater than 97%. A robotic, semi-automated method for 6-[18F]FDOPA radiosynthesis is therefore feasible. The radiation burden for the operator can be reduced as much as possible. Sufficient activity of 6-[18F]FDOPA could be obtained for positron emission tomography studies of dopaminergic function.

Dihydroxyphenylalanine↗

Correlation of magnetic resonance imaging and histological findings in a large basilar tip aneurysm after coil embolization--case report.

A 73-year-old female with a large basilar tip aneurysm underwent endovascular coil embolization with interlocking detachable coils (IDCs). The patient subsequently died of pneumonia 25 days after the embolization, and the aneurysm specimen was obtained at autopsy. Histological examination showed that the intraaneurysmal structure consisted of three layers. The outer layer was mildly organized thrombus surrounding the coils, the middle layer was disorganized clot, and the inner layer consisted of fresh blood clot. Gradient-echo magnetic resonance (MR) imaging taken before death had demonstrated a central region of high intensity and a peripheral low intensity region corresponding to the inner and middle-outer layers of the aneurysm, respectively. Intraaneurysmal placement of IDCs leads to the formation of a clot surrounding the coils. However, clot formation may be inadequate where the packing of the IDCs is incomplete. Comparison of the MR imaging and histological findings in this case show that gradient-echo MR imaging can assess thrombus and residual blood flow within the aneurysm.

Aged↗

Postoperative coma induced by hyponatremia after laparoscopy--a case report.

Hyponatremia is a common clinical entity which may occur during the course of many medical illnesses. However disastrous sequelae or even death may develop in young, generally healthy patients who receive simple elective surgery. Here we present a case of a 34-year-old female, without past history of cardiopulmonary or renal disease, after undergoing laparoscopic surgery developed mental status changes and lapsed into coma on the second postoperative day. She was found to have a serum sodium level of 110 mEq/L. After careful treatment and a protracted hospital stay, the patient recovered uneventfully. The pathophysiology of postoperative hyponatremia is discussed and attention is called to the special vulnerability of menstruant women who carry a much increased risk of mortality and morbidity associated with hyponatremia.

Adult↗

Novel approach to rotational atherectomy results in low restenosis rates in long, calcified lesions: long-term results of the San Antonio Rotablator Study (SARS).

Ablation technique and adjunctive strategy may affect restenosis after rotational atherectomy. To minimize trauma to the vascular wall, we changed the technique of rotablation as follows: the RPM range was decreased to 140,000-160,000 RPM, the ablation was performed using a repetitive pecking motion, avoiding a decrease in the rotational speed of the burr greater than 3,000 RPM, long lesions were divided into segments and each segment was separately ablated, and the burr-to-artery ratio was intended to be approximately 0.75. To prevent coronary spasm, before and after each pass, 100-200 microg nitroglycerin and 100-200 microg verapamil i.c. boluses were administered. Adjunctive PTCA was performed using a closely sized 1.1:1 balloon-to-artery ratio with a noncompliant balloon at low pressures for 120 sec. The study incorporated 111 patients with a combined total of 146 calcified lesions. Results. A total of 31.5% of patients underwent a multivessel procedure. No deaths occurred. Q-wave MI and/or creatine kinase elevation greater than three times baseline levels occurred in 4.5% of patients. By quantitative coronary angiography (QCA), the reference vessel diameter was 3.13+/-0.59 mm, mean lesion length was 33.41+/-18.58 mm. Percent stenosis and mean luminal diameter were as follows: at baseline 75.7%+/-10.8%, or 0.76+/-0.41mm, Post-rotational atherectomy 41.5%+/-3.6%, or 1.83+/-0.43 mm, Post-PTCA 18.2%+/-11.9%, or 2.56+/-0.50 mm. Six-month angiographic follow-up was available in 64 (57.7%) pts. Net luminal gain was 1.15+/-0.76 mm, with a late luminal loss of 0.65+/-0.84 mm. The mean diameter stenosis at follow-up was 37.6%+/-28.5%, with MLD 1.91+/-1.21 mm. The binary restenosis rate was 28.1%. Therefore, modification of rotational atherectomy technique with adjunctive PTCA resulted in a favorable restenosis rate in long, calcified lesions. Cathet. Cardiovasc. Intervent. 48:48-53, 1999.

Angioplasty, Balloon, Coronary↗

A fuzzy logic approach to identifying brain structures in MRI using expert anatomic knowledge.

We report a novel computer method for automatic labeling of structures in 3D MRI data sets using expert anatomical knowledge that is coded in fuzzy sets and fuzzy rules. The method first identifies major structures and then uses spatial relationships to these landmarks to recognize other structures. This labeling process simulates the iterative process that we ourselves use to locate structures in images. We demonstrate its application in three data sets, labeling brain MRI by locating the longitudinal and lateral fissures and the central sulci and then determining boundaries for the frontal lobes. Our method is adaptable to the identification of other anatomical structures.

Brain↗

Predictability of surgical results of herniated disc-induced cervical myelopathy based on spinal cord motor conduction study.

A motor evoked potential (MEP) study with percutaneous magnetic stimulation over the motor cortices and an F-wave study in peripheral nerves were performed to measure spinal cord motor conduction velocity (SCMCV) in 25 patients with herniated disc-induced cervical myelopathy (HDICM). Grading of motor function and assessment of SCMCV were performed before and 2 years after microsurgical discectomy. The results show that functional motor improvement accompanied by an increase in SCMCV occurred in grade I patients with mild neurological impairment after surgery, whereas no definite change was seen in grade II and grade III patients with moderate and severely neurological impairment. This finding suggests that measurement of SCMCV by MEP study with a noninvasive method may provide an objective and quantitative method to assessment of the functional integrity of the spinal motor pathway and that the results of such studies may serve as a predictor in evaluation of surgical outcome in patients with HDICM.

Adolescent↗

Abdominal weight and inspiratory resistance: their immediate effects on inspiratory muscle functions during maximal voluntary breathing in chronic tetraplegic patients.

OBJECTIVE: To study the immediate effects of maximal voluntary (MV) breathing, with and without abdominal weight (AW) or inspiratory resistance (IR), on inspiratory muscle functions in chronic tetraplegic patients. DESIGN: A crossover trial design. SETTING: Rehabilitation department of a university hospital. PARTICIPANTS: Nine tetraplegic men injured at the C4 to T1 levels, with a mean duration of injury of 72.8 months. INTERVENTIONS: Each subject performed MV breathing without and with AW load (AWMV breathing) and IR load (IRMV breathing) separately. MAIN OUTCOME MEASURES: Electromyographic (EMG) activity of the inspiratory muscles, mouth pressure, inspiratory flow, and inspiratory volume. RESULTS: AWMV breathing evoked greater diaphragmatic EMG activity, inspiratory flow, and inspiratory volume than did IRMV breathing, although the increase of diaphragmatic EMG activity was not statistically significant. Conversely, IRMV breathing produced greater sternocleidomastoid EMG activity and negative mouth pressure than did AWMV breathing. Both AWMV and IRMV breathing evoked greater inspiratory muscle EMG activity than did MV breathing. CONCLUSION: AW and IR loads have differential immediate effects on the inspiratory muscle functions during MV breathing in patients with chronic tetraplegia, suggesting that these two breathing maneuvers may have dissimilar mechanisms of training in such patients. The muscle EMG activity evoked during MV breathing with AW or IR is greater than that without a mechanical load, implying that mechanically loaded training in tetraplegic patients results in load compensatory adjustments via their respiratory motor output to improve respiratory function.

Abdomen↗

Terpenoids of Syzygium formosanum.

A new natural product, 4-epifriedelin (1), and 12 known terpenoids have been isolated from the leaves of Syzygium formosanum. The known compounds include caryophyllene oxide, friedelin, canophyllal, glutinol, alpha-terpineol, phytol, betulinic acid, uvaol, lupeol, betulin, ursolic acid, and oleanolic acid. All of these compounds are reported for the first time from S. formosanum.

Leukemia Virus, Murine↗

The 5' untranslated regions of the rat A2A adenosine receptor gene function as negative translational regulators.

The rat A2A adenosine receptor (A2A-R) gene contains two promoters, P1 and P2, which produce transcript 1 and transcript 2, respectively. These transcripts differ in the lengths of their 5' untranslated regions (5'UTR1: 514 bp, initiated from P1; 5'UTR2: 221 bp, initiated from P2) but encode the same protein. In the present study, we demonstrate that transcript 2 is present in various tissues at different levels, whereas transcript 1 is found only in the striatum. In the striatum, the level of transcript 2 is approximately 300-fold higher than that of transcript 1. The 5'UTR of both transcripts suppresses the expression of A2A-R and a firefly luciferase reporter gene at the translational level; this suppression is not observed after mutational inactivation of an "out-of-frame" upstream AUG codon. Translational suppression by the 5'UTR was also confirmed in cells using a bicistronic strategy. Collectively, these data suggest that P2 is the major promoter of the rat A2A-R gene. The 5'UTR of the rat A2A-R gene exerts an inhibitory effect on translation by an upstream open reading frame. Because the 5'UTR of the A2A-R gene possesses strong interspecies homology, translational suppression may be a general mechanism by which the expression of the A2A-R gene is regulated.

Animals↗

11C-acetate clearance in nasopharyngeal carcinoma.

This study assessed 11C-acetate turnover (clearance) in nasopharyngeal carcinoma (NPC). Data were acquired by dynamic PET after the intravenous injection of 4.625 MBq.kg-1 body weight of 11C-acetate for 30 min. Tomograms were reconstructed and evaluated visually. A time-activity curve of the nasopharynx and neck was generated and the clearance rate of 11C-acetate from the nasopharynx in the slow phase and from NPC was calculated using 0.693/T1/2. Ten patients with nasopharyngeal carcinoma and nine normal subjects were studied. The clearance of 11C-acetate from the normal nasopharynx was rapid and biexponential, in contrast to the rapid uptake followed by extremely slow clearance in patients with NPC. The clearance rate (mean +/- S.D.) was 0.0074 +/- 0.0042 in NPC and 0.0263 +/- 0.0152 in controls in the slow phase, being significantly different between the two groups with no overlap. All nasopharyngeal carcinomas were clearly visualized, in contrast to no obvious retention in the normal nasopharynx. Our initial results indicate that 11C-acetate clearance can be used to differentiate nasopharyngeal carcinoma from a normal nasopharynx. This finding may lead to new applications of 11C-acetate in oncology.

Acetates↗

Corneal endothelial deposits in patients with HIV infection or AIDS: epidemiologic evidence of the contribution of rifabutin.

BACKGROUND: We noted a number of patients with unusual fine, stellate corneal endothelial deposits. The distribution of the deposits appeared to be concentric, involving mostly the periphery. We postulated that the changes might be related to the use of rifabutin rather than to cytomegalovirus (CMV) retinitis. We conducted a study among patients infected with HIV to assess the factors associated with these corneal changes. METHODS: All patients with HIV infection or AIDS who presented to an ocular AIDS clinic in Vancouver between May 16 and July 4, 1996, were examined for the presence of corneal endothelial deposits. The clinical history was noted in a masked fashion. RESULTS: Of the 162 patients examined, 25 showed fine, diffuse, white, stellate corneal endothelial deposits occurring predominantly in the periphery. The presence of the deposits was associated with rifabutin use (odds ratio 5.6, 95% confidence interval 2.5 to 12.9) independent of the presence of CMV retinitis, the CD4 count, the presence of uveitis and use of other medications. INTERPRETATION: Corneal endothelial deposits found in patients with HIV infection are associated with rifabutin use independent of the presence of CMV retinitis. The deposits should be monitored to determine their clinical significance.

Acquired Immunodeficiency Syndrome↗