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Biomedical subjects

C S Chang

Publications and source records attributed to C S Chang.

At least 91 records · Page 5Linked to original sources
PubMed1998

Optimized conditions for growth and fermentation of Helicobacter pylori.

This study attempted to optimize the growth conditions of Helicobacter pylori by comparing the growth of H. pylori in an anaerobic jar and an incubator. It was found that the primary isolation rate of H. pylori from gastric biopsies was higher in an anaerobic incubator (28/30) than in an anaerobic jar (21/30). In addition, growth rate in the subsequent passage was also higher in an incubator. By comparing different supplements in the liquid media, it was found that most strains grew best in Brucella broth containing 5% fetal calf serum, and some strains grew well with the supplement of 0.2% of beta-cyclodextrin. A large scale culture using a bioreactor indicated that a defoaming agent, polypropylenglycol, profoundly inhibited the growth of H. pylori. However, fermentation could be successfully performed by continuously infusing mixed airs composed of 5% O2, 10% CO2 and 85% N2. Moreover, the production of secreted proteins of H. pylori strains grown in the bioreactor was the same as that in an anaerobic jar. Results presented herein can be used to further optimize conditions for enhancing the growth of H. pylori.

Fermentation↗
PubMed1998

Donor leukocyte infusion as salvage therapy in an adult with relapsed acute lymphoblastic leukemia after allogeneic bone marrow transplantation.

Relapse of malignancy after allogeneic bone marrow transplantation remains the major cause of treatment failure in patients with leukemia. While donor leukocyte infusion (DLI) has been used to treat such patients, its use in patients with acute lymphoblastic leukemia is seldom reported. We describe a 35-year-old woman who suffered relapse of acute lymphoblastic leukemia after allogeneic bone marrow transplantation. She received DLI twice as salvage therapy. This patient achieved complete remission following DLI and has remained in remission for more than 11 months without further chemotherapy. We suggest DLI can be used as an initial salvage therapy, without significant toxicity, for patients with relapsed acute lymphoblastic leukemia following bone marrow transplantation.

Adult↗
PubMed1998

Microsurgical management of intracranial epidermoid cysts.

BACKGROUND: Intracranial epidermoid cysts are slow-growing congenital neoplasms that usually spread and adhere to critical neurovascular structures along the basal cistern, particularly the cerebellopontine angle (CPA) and parasellar region. Clinical symptoms include trigeminal neuralgia, headache and dizziness, progressive hemiparesis, unstable gait and hemifacial spasm. With the aid of modern imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), an effective microsurgical approach can be planned preoperatively to completely remove tumors and avoid complications. METHODS: Twenty-six patients with intracranial epidermoid cysts were microsurgically treated between July 1984 and June 1997. Diagnostic procedures included enhanced CT and/or CT cisternography and MRI. All patients underwent microsurgical treatment for tumor removal. RESULTS: Total tumor removal was achieved in 12 patients (46.2%), near-total removal in seven (26.9%), partial removal in six (23.1%) and stereotactic biopsy in one patient (3.8%). Postoperative deterioration of the neurologic condition was found in three patients who required further surgery, aseptic meningitis in four patients and communicating hydrocephalus requiring shunting in three patients. The functional prognoses were excellent in 23 patients (88.5%), good in two patients (7.7%) and fair in one patient (3.8%). Among the 26 patients, three died of pneumonia three, six and nine months after surgery, respectively. CONCLUSIONS: MRI is particularly useful for defining the anatomic limits of tumor tissue and surgical planning. The surgical results were excellent in patients with near-total tumor removal, as well as in patients with total removal. Aggressive surgical tumor removal may result in transient, but significant, cranial nerve palsy and should be avoided. Perioperative administration of steroids and wound protection may be beneficial for preventing the development of postoperative aseptic meningitis and hydrocephalus.

Adult↗
PubMed1998

Salivary function in patients with reflux esophagitis: effect of cisapride.

UNLABELLED: Saliva plays an important role in esophageal acid clearance. Reduction in salivary function has been considered in the pathogenesis of reflux esophagitis. Cisapride, a prokinetic agent, has been reported effective for treating mild-to-moderate grade gastroesophageal reflux disease. Some studies have shown that cisapride increases saliva volume and acid-buffering capacity. The aim of this study was to evaluate the effect of cisapride on salivary gland function by means of dynamic salivary scintigraphy. METHODS: Fifty-five patients with endoscopic reflux esophagitis (Savary-Miller Grades I-II) were enrolled in this study. In Group 1 (n = 29), patients were evaluated during the fasting state, both before and after cisapride treatment (5 mg, 3 times/day, before meals, for 2 wk). In Group 2 (n = 26), patients were evaluated during the postprandial state, both before and after cisapride treatment. Uptake ratio (UR) and excretion ratio (ER) of the salivary gland in each group were compared using the paired Student's t-test. RESULTS: In Group 1, no significant differences were found in UR or ER after cisapride treatment. However, in Group 2, ER increased significantly after treatment (p < 0.01), but UR did not show any significant change. CONCLUSION: Cisapride can increase the secretion function of salivary glands during the postprandial phase but not the fasting phase.

Cisapride↗
PubMed1997

Mutagenesis of the positively charged conserved residues in the 5' exonuclease domain of Taq DNA polymerase.

Taq DNA polymerase from Thermus aquaticus has been shown to be very useful in the polymerase chain reaction method. Taq DNA polymerase has a domain at the amino terminus (residue 1 to 290) that has a 5' exonuclease activity and a domain at the C-terminus that catalyzes polymerase reaction. Taq DNA polymerase is classified into the pol I family which is represented by E. coli DNA polymerase I. The alignment of amino acid sequences for the 5' exonuclease domains of the pol I family DNA polymerases shows six highly conserved sequences called motifs A to F. Motif C contains three positively charged residues such as 74Arg, 82Lys and 85Arg which might be involved in catalysis. In order to understand the function of those residues, they are mutagenized to alanine. The 5' exonucleolytic activities of those mutated 5' exonucleases decreased by 80 to 90%, thereby implying that three positively charged residues play certain roles in the 5' exonuclease catalysis.

Amino Acid Sequence↗
PubMed1997

Aluminum-induced structural alterations of the precursor of the non-A beta component of Alzheimer's disease amyloid.

The precursor of the non-A beta component of Alzheimer's disease amyloid (NACP) is a presynaptic protein whose function has been suspected to be tightly involved in neuronal biogenesis including synaptic regulations. NACP was suggested to seed the neuritic plaque formation in the presence of A beta during the development of Alzheimer's disease (AD). Recombinant NACP purified through heat treatment, DEAE-Sephacel anion-exchange, Sephacryl S-200 size-exclusion, and S-Sepharose cation-exchange chromatography steps appeared as a single band on SDS-PAGE with Mr of 19 kDa. Its N-terminal amino acid sequence clearly confirmed that the protein was NACP. Interestingly, however, the protein was split into a doublet on a nondenaturing (ND)-PAGE with equal intensities. The doublet was located slightly above a 45-kDa marker protein on a 12.5% ND-PAGE. In addition, the size of NACP was more carefully estimated as 53 kDa with high-performance gel-permeation chromatography using a TSK G3000sw size-exclusion column. Recently, Lansbury and his colleagues (Biochemistry 35, 13709-13715) have reported that NACP exists as an elongated "natively unfolded" structure which would make the protein more actively involved in protein-protein interactions and Kim (Mol. Cells 7, 78-83) has also shown that the natively unfolded protein is extremely sensitive to proteases. Here, we report that the structure of NACP could be altered by certain environmental factors. Aluminum, a suspected risk factor for AD, converged the doublet of NACP into a singlet with slightly lower mobility on ND-PAGE. Spectroscopic analysis employing uv absorption, intrinsic fluorescence, and circular dichroism indicated that NACP experienced the structural alterations in the presence of aluminum such as the secondary structure transition to generate about 33% alpha-helix. This altered structure of NACP became resistant to proteases such as trypsin, alpha-chymotrypsin, and calpain. Therefore, it is suggested that aluminum, which influences two pathologically critical processes in AD such as the protein turnover and the protein aggregation via the structural modifications, could participate in the disease.

Aluminum↗
PubMed1997

Incorporating tangent refinement in the Shake-and-Bake formalism.

Shake-and-Bake is a direct-methods procedure in which phase refinement and Fourier refinement are alternated repetitively, unconditionally and automatically. The traditional Shake-and-Bake approach invoked a parameter-shift routine to perform phase refinement in an effort to reduce the value of minimal function. In this paper, parameter shift is replaced with the tangent formula as a means of phase refinement. This study shows that the tangent formula is more efficient than parameter shift for small structures when the number of refinement cycles and number of applications of the tangent formula per Shake-and-Bake cycle are chosen very carefully. For larger structures, including the 400 non-H-atom crambin structure, the two methods generally perform with similar efficiency. However, only parameter shift has successfully produced recognizable solutions for the difficult 317 non-H-atom structure gramicidin A.

Algorithms↗
PubMed1997

Stereomorphologic observation of bone tissue response to hydroxyapatite using SEM with the EDTA-KOH method.

To obtain further information on the interaction of hydroxyapatite (HA) and the bony implantation bed, 20- to 40- mesh dense HA particles were implanted into the tibiae of dogs. Following healing periods of 2 weeks, 1 month, and 3 months, the specimens were retrieved and prepared by either conventional preparatory procedures for scanning electron microscopy (SEM) of the EDTA-KOH method. Under SEM observation, the interparticular osteogenesis among HA particles progressed in a programmed sequence. Ample blood supply and osteoblasts initially presented in the interparticular space. The secretion of bone matrix resulted in the formation of immature bone. This scaffold was then transformed into mature lamellar bone during the following bone remodeling process. The serial changes closely resembled the pattern viewed in controls that did not implant HA. A spatial relationship between bone cells and HA was clearly demonstrated. In particular, the osteoblasts displayed an extremely flat appearance with many microappendages. The microappendages anchored cells to the HA surface and fused with granular material covering the HA crystals. The more characteristic cellular morphology was revealed by the EDTA-KOH method. Microscopic pictures clearly identified the three-dimensional images of ruffled borders of osteoclasts and the slender cytoplasmic processes of osteocytes. This study provided further evidence for the favorable biological response of HA to bone cells as well as the value of the EDTA-KOH method in examining the stereomorphology of bone cells.

Animals↗
PubMed1997

Surfactant effect on enhancing (S)-naproxen prodrug production from racemic naproxen by lipase.

In the enantioselective esterification of racemic naproxen with 4-(2-hydroxyethyl) morpholine by Lipase MY in organic solvents, a productivity improvement of the desired (S)-naproxen ester from 0.42 to 0.72 mM at the reaction time of 130 h was observed, when the surfactant bis (2-ethylhexyl) sodium sulfosuccinate (AOT) was added in the reaction mixture. The presence of a small amount of exogenously added water dramatically activated the enzyme in AOT/cyclohexane-reversed micelles. Desorption of the surfactant molecule from the enzyme mass and solubilization of the enzyme into reversed micelles were used to elucidate an existing maximum of the initial rate of (S)-naproxen synthesis with the water content. Moreover, the effects of alcohol and surfactant concentration on the enzyme activity are reported.

Dioctyl Sulfosuccinic Acid↗
PubMed1997

7,7-Difluoroprostacyclin derivative, AFP-07, a highly selective and potent agonist for the prostacyclin receptor.

Recently, we cloned cDNAs for the prostacyclin receptor (IP) and the four mouse PGE receptor subtypes, EP1, EP2, EP3, and EP4, and established Chinese hamster ovary cells that stably express each receptor. We examined the agonist potency and selectivity of AFP-07, a 7,7-difluoroprostacyclin derivative, compared with widely used stable prostacyclin analogue, iloprost, using the cells expressing each cloned receptor. AFP-07 strongly displaced the [3H] iloprost binding to the IP receptor-expressing cell membranes, the half maximal concentration for the displacement being 3 nM, which was one order lower than that of iloprost. AFP-07 concentration-dependently stimulated cAMP formation in the IP-expressing cells, the half-maximal concentration for the stimulation being 10 pM, which was one order lower than that of iloprost. On the other hand, AFP-07 showed lower affinity for EP1, EP2, EP3, and EP4 than PGE2, but iloprost had the same affinity as PGE2 for the EP1, These results demonstrate that AFP-07 is a potent and highly selective agonist for the IP receptor.

Animals↗
PubMed1997

Characterization of functional interaction of carboxylic acid group of agonists and arginine of the seventh transmembrane domains of four prostaglandin E receptor subtypes.

Prostaglandin (PG) E2 binds to four PGE receptor subtypes, EP1, EP2, EP3 and EP4, and induces a variety of functions through the interaction of carboxylic acid of PGE2 and Arg residue in the seventh transmembrane domain of the receptor. To assess the role of the interaction of the carboxylic acid group of agonists and the Arg residue, which can form both ionic bonding and hydrogen bonding as a hydrogen donor, we examined the agonist activities of three types of agonist, PGE2 with a negatively charged carboxylic acid, PGE2 methylester, which is a hydrogen acceptor, and 1-OH PGE2, which can accept as well as donate hydrogen but prefers to donate hydrogen rather than accept it, for four PGE receptor subtypes. Although PGE2 methylester had slightly lower agonist activities than PGE2 for EP1 and EP4 receptors, PGE2 and its methylester showed the same agonist activities for EP2 and EP3 receptors, indicating that PGE2 methylester is a potent agonist for all of the four subtypes. In contrast, 1-OH PGE2 was a very weak agonist for all receptors. These findings demonstrate that the hydrogen bonding interaction of agonists and the Arg residue is generally sufficient for the functional activation of all of the PGE receptor subtypes.

Animals↗
PubMed1997

Comprehensive gastric emptying study for type-II diabetes mellitus dyspeptic patients.

BACKGROUND: Gastrointestinal symptoms without demonstrable lesions in the upper gastrointestinal tract are common in diabetic patients. Scintigraphic liquid- and solid-phase gastric emptying studies and gastric emptying of indigestible particles were performed to determine the gastric emptying function in type-II diabetes mellitus patients with dyspepsia. METHODS: Twenty type-II diabetic patients with symptoms suggestive of delayed gastric emptying were included. A gelatin capsule containing 10 rod-shaped radiopaque markers was ingested, along with the solid-phase test meal, to assess the emptying of indigestible particles. Scintigraphic liquid-phase gastric emptying studies were performed on a separate day. RESULTS: There were 7 patients (35%) with delayed liquid-phase gastric emptying, 14 patients (70%) with delayed solid-phase gastric emptying, and 14 patients (70%) with abnormal gastric emptying of indigestible particles. There were only three patients (15%) with normal gastric emptying of both the liquid and solid phase. Furthermore, only one patient showed normal result in all three gastric emptying studies. CONCLUSIONS: For determining abnormalities in gastric emptying function for type-II diabetic dyspepsia patients, comprehensive gastric emptying studies, including scintigraphic liquid- and solid-phase gastric emptying studies and gastric emptying of indigestible particles, are most helpful.

Aged↗
PubMed1997

Comparison of intravenous granisetron with metoclopramide plus dexamethasone in the prevention of nausea and vomiting associated with emetogenic cytotoxic chemotherapy.

Fifty-one patients who received their first course of chemotherapy were studied to compare the respective efficacy and safety of granisetron and metoclopramide plus dexamethasone in the prevention of nausea and vomiting induced by emetogenic cytotoxic drugs. The results showed the response rate of antiemesis in the first 24 hours was higher in the metoclopramide plus dexamethasone group than in the granisetron group: 95% vs 84%. For the next six days of the study period, the response rate of the granisetron group was shown to be more effective than that of metoclopramide plus dexamethasone group: 77% vs 60%. Furthermore, the granisetron seemed to display enhanced tolerability with less drug-related side effects and no extrapyramidal effects which appeared in 2 cases of the metoclopramide plus dexamethasone group. In conclusion, a single dose of granisetron can be as effective as the gold standard of metoclopramide plus dexamethasone regimen in preventing and treating acute nausea and vomiting. For preventing delayed nausea and vomiting, granisetron is shown to be more effective than metoclopramide plus dexamethasone.

Adult↗
PubMed1997

High dose chemotherapy with peripheral blood stem cells transplantation in patients with relapsed or refractory lymphomas preliminary reports.

High dose chemotherapy with peripheral blood stem cells transplantation (PBSCT) has been used worldwide in the treatment of patients with various hematological malignancies and other solid tumors. It has just come into use as a salvage therapy in various malignancies in Taiwan in recent years. We report eight cases with relapsed or refractory lymphoma treated with high dose chemotherapy and PBSCT. Our results showed all cases but one achieved complete remission. The mean days of white cell recovery were 10 days to > 500/microliter (ranges, 8-16 days) and 12 days to > 1,000/microliter (ranges, 9-19 days). The mean days to platelet transfusion independent, i.e. platelet > 20,000/microliters, was 14 days. No specific side effect was noted except death in one case on D+9 during cytopenia state. Four patients relapsed and died during the follow-up after PBSCT. From our preliminary results we suggest that high dose chemotherapy with PBSCT could be used as a salvage therapy in patients with relapsed or refractory lymphomas with favorable and sustained hematological recovery. Most cases were tolerable with myeloablative chemotherapy and re-achieved remission, however, remission duration was still short and relapse remained the main problem to be overcome. The long term effects of high dose chemotherapy with PBSCT still need further study.

Adolescent↗
PubMed1997

The incidence of reflux esophagitis among the Chinese.

OBJECTIVES: Very few epidemiological data on reflux esophagitis in Chinese are available in the literature. METHODS: To evaluate the incidence of reflux esophagitis, upper gastrointestinal endoscopies were performed on 2044 patients (male 1266, female 778; age range 16-82 yr) during a 6-month period. RESULTS: The overall incidence of reflux esophagitis was 5%, and most of the patients (86.3%) had a mild grade of esophagitis. Hiatal hernia was found in 44 patients (2.2%); those patients were significantly older than those without hiatal hernia (60.3 +/- 10.8 vs. 49.4 +/- 12.1 yr, p < 0.05). Patients with symptoms suggesting gastroesophageal reflux (acid regurgitation, heartburn, and belching) had higher incidence of esophagitis (22.9%, 22.5%, and 24.7%, respectively). The body mass index was significantly higher in patients with esophagitis than in those without esophagitis (25.7 +/- 3.1 vs. 24.0 +/- 3.6, p < 0.05). The male:female ratio for esophagitis was 5.6:1. No esophagitis was found in patients who were less than 21 yr old. However, there was a difference in age group distribution for the incidence of esophagitis. The habit of coffee or tea drinking does not contribute to the development of esophagitis. CONCLUSIONS: Based on the results of this study, the incidence of endoscopic reflux esophagitis among the Chinese is 5%, which is lower than in Western countries.

Adolescent↗
PubMed1997

Correlation between patterns of antral contractility and gastric emptying of radiopaque markers.

OBJECTIVES: Gastric clearance of radiopaque markers (ROMs) has been proposed as an easy and noninvasive technique for assessment of gastric emptying. This study was conducted to evaluate the role of antral obliterating contractions in gastric emptying of ROMs in healthy volunteers. METHODS: Fifteen healthy volunteers, 12 males and three females, aged 21-38 yr, were enrolled in this study. Simultaneous recording of scintigraphic solid phase gastric emptying, gastric clearance of ROMs, and gastric manometry were performed after an overnight fast. The data of scintigraphic solid phase gastric emptying were expressed by half-emptying time (t1/2). The ROMs remaining in the stomach were counted fluoroscopically 2.5 and 4.5 h after the test meal. The time for the appearance of antral obliterating contractions after the meal was calculated. RESULTS: Six subjects (40%) passed all 10 ROMs after 4.5 h of recording. Among these six subjects, five had antral obliterating contractions 190-251 min (mean 232.2 +/- 24.3 min) after the test meal. There was no significant difference in t1/2 between subjects with or without antral obliterating contractions within the 4.5 h of recording. CONCLUSIONS: There was a considerable intersubject variation in the time of first antral obliterating contraction after the test meal. In the healthy volunteers, all ROMs were passed when there was a postprandial antral obliterating contraction. However, some of the ROMs still passed from the stomach in the absence of antral obliterating contractions.

Adult↗
PubMed1997

Ambulatory 24-hour esophageal manometry and pH-metry in patients with noncardiac chest pain, but no reflux symptoms.

The aim of this study is to determine the diagnostic value of 24-hour ambulatory esophageal manometry and pH-metry for patients with noncardiac chest pain (NCCP), but no reflux symptoms. Twenty-four hour ambulatory esophageal manometry and pH-metry was performed on 34 patients with NCCP, but no reflux symptoms. The pressure transducers were located 3, 8, and 13 cm above the lower esophageal sphincter (LES) and the pH probes were located 5 and 20 cm above the LES. An event marker was triggered by the patient for chest pain. Only 17 patients (50%) had at least one pain episode (total 81 episodes, range 1-19 episodes per person) during a 24-hour recording. Twenty-one chest pain episodes (26%) occurred during abnormal motility, whereas 4 episodes (5%) were associated with pH < 4, and 10 episodes (12%) had both abnormalities. The majority of chest pain episodes, 46 out of 81 events (57%), did not have any association with motility or pH abnormalities. Five of 7 patients (71%) with reflux-related chest pain and 8 of 11 patients (73%) with dysmotility-related chest pain had symptom association probability > 95%, indicating a significant association between chest pain and esophageal dysfunction. Our conclusion is that ambulatory esophageal manometry and pH-metry is a useful tool in the evaluation of NCCP, but only a few additional patients with reflux-related chest pain could be found in patients without reflux symptoms.

Adult↗