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Biomedical subjects

S K Chang

Publications and source records attributed to S K Chang.

At least 37 records · Page 2Linked to original sources
PubMed1998

p53 mutation in patients with ulcerative colitis in rectal biopsy.

OBJECTIVES: Long standing ulcerative colitis (UC) has been known to be one of the precancerous diseases of colorectal cancer. Although the frequent loss of p53 allele (LOH) and aneuploidy were reported as the molecular events in carcinoma and dysplasia known as the precursor of UC, p53 genetic alteration was not reported in indefinite dysplasia and UC involved mucosa in long standing UC. Therefore, we investigated the mutational inactivation of the p53 gene in UC patients who showed dysplastic mucosa, as well as non-dysplastic mucosa on H & E stain and, secondly, if there is p53 mutation, we examined the relationship between p53 alteration and clinical data. METHOD: Sixteen patients with UC who had different duration of colitis were studied by endoscopic examination with rectal mucosal biopsies, p53 gene alterations were detected by PCR-SSCP for exon 4-8 and immunohistochemical staining with p53 monoclonal antibody. RESULTS: Among 16 patients, 2 patients (12%) showed dysplasia on H-E stain. The p53 point mutations were detected in 4 (two dysplasia and 2 normal looking mucosa) on PCR-SSCP. 4 patients who had p53 gene mutation were positive in immunohistochemical staining. With regard to clinical characteristics, these patients with p53 point mutation showed poor response to medical treatment. CONCLUSION: These results suggest that the p53 mutation may be an early molecular event of cancerous change in UC.

Adolescent↗
PubMed1997

An E. coli B mutation, rpoB5081, that prevents growth of phage T4 strains defective in host DNA degradation.

An E. coli B Tab strain, EM121, was isolated that restricts T4 denA (DNA endonuclease II) mutants at 37 degrees C and above, but is permissive for wild-type T4 at all temperatures examined. At 42 degrees C, other mutants affected in nucleic acid metabolism (T4 dexA, regA and uvsW strains) are also restricted. Genetic analysis revealed that one mutation (rpoB5081) in the RNA polymerase beta subunit gene is sufficient for restricting all denA mutants. rpoB5081, together with a second linked mutation, is also required for restricting the other T4 mutants, rpoB5081 (P806S), previously shown to increase transcription termination in E. coli K-12, causes delayed synthesis of T4 late proteins and reduced DNA synthesis in denA infections. Thus, T4 DNA synthesis and gene expression are impaired by the rpoB5081 beta subunit when degradation of host DNA is reduced. Because the restricted T4 mutants are not readily distinguished from wild-type phage under typical plating conditions, EM121 is an important host for screening and mapping T4 denA mutations.

Alleles↗
PubMed1997

Characterization of superoxide dismutase in Streptococcus thermophilus.

Streptococcus thermophilus AO54 possesses a single manganese-containing superoxide dismutase (MnSOD). The enzyme was found to be insensitive to cyanide or to a modified H2O2 treatment. The enzyme is expressed in a growth-phase-dependent fashion, increasing three- to fourfold upon entry into stationary phase. The specific activity for MnSOD was the same under anaerobic or aerobic conditions and was not induced by the presence of paraquat under aerobic conditions.

Aerobiosis↗
PubMed1997

Heat strain models applicable for protective clothing systems: comparison of core temperature response.

Core temperature (Tc) output comparisons were analyzed from thermal models applicable to persons wearing protective clothing. The two models evaluated were the United States (US) Army Research Institute of Environmental Medicine (USARIEM) heat strain experimental model and the United Kingdom (UK) Loughborough (LUT25) model. Data were derived from collaborative heat-acclimation studies conducted by three organizations and included an intermittent-work protocol (Canada) and a continuous-exercise/heat stress protocol (UK and US). Volunteers from the US and the UK were exposed to a standard exercise/heat stress protocol (ambient temperature 35 degrees C/50% relative humidity, wind speed 1 m/s, level treadmill speed 1.34 m/s). Canadian Forces volunteers did an intermittent-work protocol (15 min moderate work/15 min rest at ambient temperature of 40 degrees C/30% relative humidity, wind speed approximately 0.4 m/s). Each model reliably predicted Tc responses (within the margin of error determined by 1 root mean square deviation) during work in the heat with protective clothing. Models that are analytically similar to the classic Stolwijk-Hardy model serve as robust operational tools for prediction of physiological heat strain when modified to incorporate clothing heat-exchange factors.

Acclimatization↗
PubMed1997

Utilization of Chinese medicine in Taiwan.

This article examines the use of Chinese medicine in Taiwan. Based on a national sample survey, the authors investigated how Chinese medicine is being used and factors that are associated with its use among the Taiwanese. Results of the study suggest that Chinese medicine use among this population depends on health conditions, and that having a regular source of care for Chinese medicine as well as a preference for Chinese medicine are two predictors for its use. Policies on the integration of Chinese medicine or other traditional medicine into the modern healthcare system are recommended.

Adolescent↗
PubMed1996

Comparison of inversion recovery fast spin-echo (FSE) with T2-weighted fat-saturated FSE and T1-weighted MR imaging in bone marrow lesion detection.

OBJECTIVE: To prospectively compare inversion recovery (IR) fast spin-echo (FSE) with T1-weighted spin-echo (SE) and T2-weighted chemical-shift fat-saturated (FS) FSE magnetic resonance sequences in the detection of bone marrow abnormality. DESIGN: Twenty-nine sets of T1-weighted SE [400-640/10-20 (TR/TE)], T2-weighted FS-FSE [2400-3800/91-112/8 (TR/TE/ETL), and IR-FSE [3700-6000/12-14/170/8 (TR/TE/T1/ETL)] images were acquired with a 1.5-T magnet in 27 patients with bone marrow lesions. The visibility, margination, and extent of 41 lesions, image quality, contrast, and artifacts were qualitatively and quantitatively compared. RESULTS: The lesions were more conspicuous on the IR-FSE than on the T1-weighted SE and T2-weighed FS-FSE images. The extent of lesions was similar for all three sequences. Image quality was better and there were fewer motion artifacts on the T1-weighted images. The mean lesion contrasted-to-noise ratio was significantly higher on the T1-weighted images (p < 0.05). CONCLUSION: The IR-FSE sequence is highly sensitive for detecting bone marrow pathology, with scan time comparable to the T1-weighted SE and T2-weighted FS-FSE sequences.

Adult↗
PubMed1996

The practice of Chinese medicine in Taiwan.

This paper examines the practice of Chinese medicine in Taiwan. Using a national sample survey of Chinese medicine physicians, supplemented by another national survey of Chinese medicine hospitals and government records, the authors study the education and training background of Chinese medicine physicians, their mode of practice, their productivity measured by patient visits, and the practice characteristics of Chinese medicine hospitals. Moreover, the authors investigate the relationship between the resource input, the public health insurance contract, and the number of patient visits Chinese medicine physicians provided. Results of this study are used to make several recommendations on the appropriate way of integrating the practice of Chinese medicine into the modern health care system. Many of these recommendations may also be applicable to other countries that are contemplating integrating traditional or alternative medicine into their health care systems.

Adult↗
PubMed1996

Extraskeletal Ewing's sarcoma presenting with pulmonary embolism.

Small round cell tumours with the morphologic characteristics of Ewing's sarcoma arise rarely in soft tissues of the extremities, retroperitoneum, chest and orbit. Patients usually present with symptoms arising from the swelling at the primary site. We report on a patient with a retroperitoneal extraskeletal Ewing's sarcoma who presented with massive tumour embolism to the pulmonary vasculature. To our knowledge, this is the first report of extraskeletal Ewing's sarcoma presenting with pulmonary tumour embolism.

Adult↗
PubMed1996

Helicobacter pylori infection and serum pepsinogen I concentration in peptic ulcer patients: effect of bacterial eradication.

OBJECTIVES: In order to test the hypothesis that H. pylori infections in the gastric antrum increase pepsinogen I release, fasting serum pepsinogen I concentrations were compared in peptic ulcer patients with and without H. pylori infection. A randomized prospective study was performed to determine whether the increased serum pepsinogen I concentrations associated with H. pylori infection respond to treatment that eradicates H. pylori. METHODS: Fasting serum pepsinogen I concentrations were measured by RIA in 736 patients with endoscopically and histologically confirmed benign peptic ulcer with and without H. pylori infection. Out of 511 patients with H. pylori infection, 110 patients (group 1) were randomly selected and were treated with metronidazole and tripotassium dicitrato bismuthate combined with ranitidine and antacid, and 97 patients (group 2) were treated only with ranitidine and antacid. The third group, 54 patients free of H. pylori infection, was designed to evaluate the influence of H2-receptor antagonist and antacid on the change of pepsinogen I. Fasting pepsinogen I concentration and H. pylori status were compared before and after the treatment. RESULTS: Patients infected by H. pylori (gastric ulcer 208, duodenal ulcer 303; total 511) had significantly higher fasting serum pepsinogen I concentrations than H. pylori negative patients (gastric ulcer 110, duodenal ulcer 115; total 225). Mean pepsinogen I level of the former was 124.3 +/- 46.9 and that of the latter was 77.9 +/- 25.8 ng/ml. (p < 0.0001). The difference in serum pepsinogen I concentrations according to the location of ulcer crater was significant only in non-infected subjects e.g., mean pepsinogen I level H. pylori-negative gastric ulcer was significantly lower than that of H. pylori-negative duodenal ulcer patients. H. pylori was eradicated in all the patients who had received antibacterial therapy for 4 weeks and serum pepsinogen I concentrations were significantly decreased from 129.8 +/- 43.0 to 82.4 +/- 24.0 ng/ml after eradication of the organism. (p < 0.0001) In contrast, H. pylori-positive patients who had not received antibacterial therapy were still infected at the completion of the study and there was no significant change in the serum pepsinogen I concentrations after the treatment (120.8 +/- 40.9 vs 126.3 +/- 40.4 ng/ml). (p > 0.57) None of the patients who were initially H. pylori-negative has been reinfected during the period of the study and their serum pepsinogen I concentrations were not changed. (pre-treatment value 75.1 +/- 8.0; post-treatment value 77.3 +/- 24.5 mg/ml) (p < 0.75) Four-to six-week therapy of H2-receptor antagonist and antacid did not exert any influence on serum pepsinogen I concentrations. CONCLUSIONS: On the basis of our results, we have confirmed that the chronic infection of H. pylori of gastric antrum in peptic ulcer patients causes increased pepsinogen I release into the circulation, and eradication of the organism results in significant fall in serum pepsinogen I concentrations.

Adult↗
PubMed1996

Clothing insulation in a hypobaric environment.

HYPOTHESIS: Clothing insulation is the result of complex interactions between heat transfer mechanisms and clothing material thermal resistances. Hypobaria changes the heat transfer processes therefore should have observable effects on the clothing insulation. METHODS: The effect of hypobaria on the thermal insulative properties of U.S. Army fatigue uniform (BDU) and U.S. Army chemical protective overgarment (BDO) were examined Barometric pressure of 429 mmHg, comparable to the condition at terrestrial elevation of 4570 m (15,000 ft) above sea level was created in a hypobaric chamber. The sea level environment was used as a baseline condition. RESULTS: Our data support a diminished convective heat transfer and an enhanced evaporative heat transfer at higher altitude. We also found that hypobaria had only a small effect on the intrinsic clothing insulation values. For the less insulative BDU, hypobaria did not appreciably affect clothing insulation values. For the more insulative BDO, a maximum difference of 0.2 clo (clo = 0.155 m2.K.W-1) was found between hypobaric and normobaric environments. CONCLUSION: Heavy clothing insulation forced the heat transfer processes at the skin surface to operate almost independently from those at the clothing surface. At the skin surface, evaporation was the dominant process, while at the outer clothing surface, convection dominated. At higher altitude, enhanced evaporative heat transfer resulted in a lower skin temperature, while reduced convective heat transfer hampered heat dissipation from clothing surface to the ambient environment, hence elevating the clothing temperature. Therefore, in hypobaric environment, the skin temperature was found to be lower, but the clothing temperature higher than at sea level.

Adolescent↗
PubMed1995

Availability of discographic computed tomography in automated percutaneous lumbar discectomy.

Automated percutaneous lumbar discectomy (APLD) has been developed since 1984 when Gary Onik first attempted it. This procedure has many advantages and has been used widely in the treatment of protruded disc diseases. The success rate of APLD by authors from March 1988 to February 1993 when the discographic computed tomography (CT) had not been performed was 74%. In evaluating lumbar disc diseases, we have used discographic CT. According to the patterns of dye distribution in the disc, two different types of protrusion can be distinguished: broad dye base protrusion and narrow dye base protrusion. From April 1993 to July 1994, 52 patients with protruded disc diseases were performed discographic CT. 23 Patients had narrow dye base protrusion and 29 patients had broad dye base protrusion. 29 patients with a broad dye base on discographic CT were treated with APLD and evaluated. The success rate in these patients was 93% by Macnab's criteria. Thus, we suggest that it is mandatory to apply discographic CT to increase the success rate of APLD in patients with protruded disc diseases.

Adolescent↗
PubMed1994

Percutaneous absorption, dermatopharmacokinetics and related bio-transformation studies of carbaryl, lindane, malathion, and parathion in isolated perfused porcine skin.

The percutaneous absorption of topically applied pesticides is a primary route for systemic exposure and potential toxicity. The isolated perfused porcine skin flap (IPPSF) is an in vitro model for studying percutaneous absorption of xenobiotics as well as cutaneous metabolism and toxicity in an anatomically intact viable skin preparation. In the present studies, percutaneous absorption of four different pesticides, carbaryl (C), lindane (L), malathion (M), and parathion (P), was assessed topically in an ethanol vehicle. A 4-compartment pharmacokinetic model was utilized to model their absorption profile. The order of absorption was C > P > L > M for the 8-h experimental period, but C > L > P > M for a model-extrapolated 6-day prediction. Metabolism of C and P was also assessed by high performance liquid chromatography (HPLC). The HPLC results indicate a significant first-pass effect for both pesticides after topical application, with parathion being metabolized to paraoxon and para-nitrophenol and carbaryl to naphthol. In addition, comparison of the metabolic data of P with previous results underscores the difference between non-recirculating and recirculating IPPSF systems in xenobiotic metabolism studies.

Animals↗
PubMed1994

Localization of mucin (MUC2 and MUC3) messenger RNA and peptide expression in human normal intestine and colon cancer.

BACKGROUND/AIMS: Several studies have reported Northern blot data showing that mucin is expressed in a tissue-specific manner. To determine whether expression is limited to specific cell types within these tissues requires histological analysis. METHODS: Both immunocytochemistry and in situ hybridization were used to identify cell types expressing the MUC2 and MUC3 mucins in the human small intestine, colon, and colon carcinoma. RESULTS: In the normal small intestine and colon, an antibody recognizing the MUC2 apomucin stained goblet cells. In contrast, an antibody recognizing the MUC3 apomucin stained both goblet and absorptive cells. Consistent with this, in situ hybridization showed MUC2 messenger RNA (mRNA) only in goblet cells and MUC3 mRNA in both goblet and absorptive cells. In several samples of moderately well-differentiated colon cancer, MUC2 and MUC3 showed distinct patterns of expression, but the expression level of each was reduced compared with levels in normal tissue; there was considerable tumor-to-tumor and cell-to-cell variability using both mucin antibodies and complementary DNA probes. CONCLUSIONS: Individual mucin genes have distinct patterns of expression within mucin-producing tissues, suggesting that the various mucin gene products play distinct functional roles.

Colon↗
PubMed1994

Percutaneous absorption of topical parathion through porcine skin: in vitro studies on the effect of environmental perturbations.

Topical use of pesticides in domestic animals such as swine is a common practice; however, the effect of environmental factors on the extent of absorption has not received attention. Since no single factor can exert its effects alone in the natural environment, the interaction of environmental factors on the percutaneous absorption of pesticides must be understood before potential toxicity of dermal absorption of pesticides can be effectively estimated. In the present studies, the effects of air temperature (Ta), perfusate temperature (Tp), perfusate flow (F) and relative humidity (%RH) on absorption of parathion were studied in vitro in porcine skin. Parathion absorption was determined by measuring radiolabel appearing in the perfusate over time. Three main environmental parameters were found to have a significant effect on parathion penetration. Increasing Ta from 37 degrees C to 42 degrees C, %RH from 60% to 90% or F from 4 ml/h to 8 ml/h each produced a significant increase in penetration. The following significantly positive two-way interactions among test parameters were seen: Ta x F and %RH x F at the 4 micrograms dose, %RH x F at the 40 micrograms dose and Ta x %RH, Ta x F and %RH x F at the 400 micrograms dose. There were no three-way interactions at any of the three doses tested. These results suggest that the factors tested are not independent variables and must be considered interactive when used in assessing pesticide percutaneous absorption.

Animals↗
PubMed1993

Food.

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Animals↗