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H Chang

Publications and source records attributed to H Chang.

At least 145 records · Page 8Linked to original sources
PubMed1997

Platelet-activating factor (PAF) up-regulates plasma and tissue PAF-acetylhydrolase activity in the rat: effect of cycloheximide.

Platelet-activating factor (PAF) is a proinflammatory phospholipid mediator implicated in necrotizing enterocolitis. Regulation of PAF-acetylhydrolase (AH), the enzyme degrading PAF, is poorly understood. In this study we found that administration of a dose of PAF (1.5 microg/kg, i.v.), which does not cause gross intestinal injury, increased plasma and intestinal PAF-AH in the rat. Cycloheximide (CHX, 5 mg/kg, i.v.) reduced the activity of plasma (but not intestinal tissue) AH in control, as well as in PAF-injected rats, and aggravated systemic inflammation and tissue injury in the latter. The intestinal necrosis induced by PAF and CHX was ameliorated by posttreatment with WEB2170 (a PAF antagonist), indicating a role of endogenous PAF in mediating injury. Both WEB2170 and anti-TNF antibody reduced PAF-induced AH activity in intestinal tissue, but not in the plasma. Allopurinol largely prevented the injury induced by PAF and CHX, but had no effect on the up-regulation of AH. We conclude: 1) de novo protein synthesis is required to maintain physiologic AH level in the plasma; 2) PAF up-regulates plasma and intestinal AH activity; 3) CHX enhances the injurious effect of PAF; 4) endogenous PAF and TNF also play a role in the up-regulation of intestinal AH; the former probably mediating the intestinal injury by PAF; and 5) reactive oxygen species may mediate the injurious effect of PAF plus CHX, but do not contribute to the regulation of AH by PAF.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1996

Identification of a cDNA encoding a thiazide-sensitive sodium-chloride cotransporter from the human and its mRNA expression in various tissues.

We report here the identification of a cDNA encoding a human thiazide-sensitive sodium-chloride cotransporter (hTSC) using a PCR-based method. The homology of the hTSC with rat TSC (rTSC) and rat bumetanide-sensitive sodium-potassium-chloride cotransporter (rBSC) was 86% and 64%, respectively, at the nucleotide level, and 92% and 61%, respectively, at the amino acid level. Using fluorescence in situ hybridization (FISH), the hTSC gene has been mapped to chromosome 16q13. Northern blot analysis using polyA+RNA from various human tissues, revealed a major 4.5 kb transcript and a minor 6.5 kb specifically in the kidney, but low level of expression was also observed in small intestine, placenta, prostate, colon, and spleen.

Amino Acid Sequence↗
PubMed1996

Platelet activating factor and endotoxin increase the enzyme activity and gene expression of type II phospholipase A2 in the rat intestine. Role of polymorphonuclear leukocytes.

Type II phospholipase A2 (PLA2-II) may regulate eicosanoid synthesis; is involved in various inflammatory processes, septic shock, and inflammatory bowel disease; and is up-regulated by LPS and inflammatory cytokines in vitro. We have previously shown that the platelet-activating factor (PAF)-induced intestinal injury is attenuated by peptido-leukotriene antagonists, suggesting a role of PLA2. The purpose of this study is to examine the regulation of intestinal PLA2-II by PAF and LPS. Using synthesized competitor RNA as competitor, we quantified PLA2-II transcripts by competitive reverse transcription-PCR. We found that PLA2-II gene is constitutively expressed in the rat ileum. PAF at a dose (1.5 micrograms/kg) below that causing intestinal injury rapidly up-regulated intestinal PLA2-II at both transcriptional and post-transcriptional levels, almost tripling its transcripts and significantly increasing enzyme activity in 30 min. LPS (5 mg/kg) also up-regulated PLA2-II. This effect could not be blocked by PAF antagonist. Depletion of circulating polymorphonuclear leukocytes (PMNs) abolished the effect of PAF on PLA2-II gene expression and enzyme activation. In contrast, PMN depletion prevented LPS-induced PLA2-II enzyme activity but enhanced the gene expression. We conclude that: 1) both PAF and LPS induce gene transcription and enzyme activation of PLA2-II in the small intestine; 2) PAF up-regulates PLA2-II via PMN activation; 3) LPS effect is independent of endogenous PAF formation; and 4) different pathways exist for PAF and LPS in the regulation of intestinal PLA2-II gene expression in vivo.

Animals↗
PubMed1996

Deletion and mutation analyses of the P16/MTS-1 tumor suppressor gene in human ductal pancreatic cancer reveals a higher frequency of abnormalities in tumor-derived cell lines than in primary ductal adenocarcinomas.

The putative tumor suppressor gene p16/CDKN2 encodes a specific inhibitor of cyclin D-cyclin-dependent kinase 4 complexes important in cell-cycle regulation and has been found to be deleted or mutated in a variety of human cancers. Thirty microdissected primary human ductal pancreatic carcinomas from patients not subject to radiotherapy or chemotherapy prior to surgical resection of their carcinomas and 18 human pancreatic carcinoma cell lines were analyzed by single-strand conformation polymorphism (SSCP) and DNA sequence analyses and PCR-based deletion analyses for mutations and homozygous deletions of the p16/CDKN2 gene, respectively. Homozygous deletions of the gene were found in five cell lines, and nonpolymorphic SSCP and DNA sequence alterations were found within exon 1 in four cell lines and exon 2 in three lines, for an overall frequency of deletions and mutations of 66%. In contrast, homozygous deletions of p16/CDKN2 were observed in three primary pancreatic carcinomas, and five primary tumors revealed SSCP and/or sequence abnormalities in exon 1 (one case) and exon 2 (four cases), a mutation and deletion frequency of 27%. Immunoblotting analyses confirmed the absence of p16/MTS-1 expression in actively proliferating cell lines with a homozygous deletion of the gene and low-to-moderate levels of p16/MTS-1 expression in cell lines possessing a normal RB-1 gene or protein. These findings suggest that, although p16/CDKN2 may play a role in the pathobiology of pancreatic cancer, inactivation of this putative tumor suppressor gene occurs more frequently in cell lines than in primary ductal pancreatic carcinomas.

Adenocarcinoma↗
PubMed1996

Effects of short-term dietary change from high fat to high carbohydrate diets on the storage and utilization of glycogen and triacylglycerol in untrained rats.

The effects of short-term diet change from high fat (F) to high carbohydrate (C) (or vice versa) on the storage and utilization of glycogen and triacylglycerol (TG) in muscle and liver were studied in untrained rats. Rats were fed on an F or C diet for 28 days. For an additional 3 days, half of the rats in both F and C groups were fed the same diets as before (F-F and C-C) and the other half of the rats were switched to the counterpart diets (F-C and C-F). On the final day of the experiment, half of the rats in each diet group were exercised by swimming for 1.5 h and the other half were rested. Short-term diet change from F to C diets increased, but the change from C to F diets decreased, glycogen stores of soleus and plantaris muscles and liver, resulting in no difference in glycogen stores between F-C and C-C, and between F-F and C-F. The dietary change also had an affect on TG stores of red gastrocnemius muscle and liver-however, muscle TG stores were still higher in F-C than in C-C and C-F, and there were no differences in liver TG stores between F-C and C-F. Exercise decreased muscle glycogen contents markedly in F-C and C-C, whereas, it decreased muscle TG concentrations in F-F and C-F. Liver glycogen depletion was lower in F-C than in other groups. Lipolytic activities of epididymal adipose tissue at rest and postexercise were no differences between F-F and F-C, and were higher in F-C than in C-C and C-F. beta-adrenergic receptor binding was determined with [125I] iodocyanopindolol, and maximal numbers of beta-adrenergic receptor of plasma membrane from perirenal adipose tissue were approximately 170%-200% higher in F-C than in other groups at rest and postexercise. These results suggested that short-term C diet fed rats adapted to F diet enhanced not only glycogen stores of muscle and liver but also did not decrease lipolytic activity of adipose tissue with increased beta-adrenergic receptor density, resulting in the preservation of energy reserves (glycogen and TG) of muscle at rest, and liver glycogen sparing during exercise.

Adipose Tissue↗
PubMed1996

Anticonvulsant activity of novel derivatives of 2- and 3-piperidinecarboxylic acid in mice and rats.

The relative ability of derivatives of 2-piperidinecarboxylic acid (2-PC; pipecolic acid) and 3-piperidinecarboxylic acid (3-PC; nipecotic acid) to block maximal electroshock (MES)-induced seizures, elevate the threshold for electroshock-induced seizures and be neurotoxic in mice was investigated. Protective index (PI) values, based on the MES test and rotorod performance, ranged from 1.3 to 4.5 for 2-PC benzylamides and from < 1 to > 7.2 for 3-PC derivatives. PI values based on elevation of threshold for electroshock-induced seizures and rotorod performance ranged from > 1.6 to > 20 for both types of derivatives. Since preliminary data indicated that benzylamide derivatives of 2-PC displace [3H]1-[1-(2-thienyl)-cyclohexyl]piperidine (TCP) binding to the phencyclidine (PCP) site of the N-methyl-D-aspartate (NMDA) receptor in the micromolar range and such low affinity uncompetitive antagonists of the NMDA receptor-associated ionophore have been shown to be effective anticonvulsants with low neurological toxicity, the 2-PC derivatives were evaluated in rat brain homogenates for binding affinity to the PCP site. Although all compounds inhibited [3H]TCP binding, a clear correlation between pharmacological activity and binding affinity was not apparent. Select compounds demonstrated minimal ability to protect against pentylenetetrazol-, 4-aminopyridine- and NMDA-induced seizures in mice. Corneal and amygdala kindled rats exhibited different sensitivities to both valproic acid and the nonsubstituted 2-PC benzylamide, suggesting a difference in these two models. Enantiomers of the alpha-methyl substituted benzylamide of 2-PC showed some ability to reduce seizure severity in amygdala kindled rats.

4-Aminopyridine↗
PubMed1996

Acute pancreatitis masquerading as testicular torsion.

A 40-year-old man presented with fat necrosis of scrotum as the complication of acute pancreatitis. Excessive fluid accumulation in the pancreas and the extrapancreatic spaces, including around the spermatic cord, was seen on computed tomography. Surgical specimen showed typical fat necrosis of tunica vaginalis and the spermatic cord. After the surgery, pain of the testicle subsided completely, without recurrence. From the clinical presentation alone, it had been difficult to differentiate this patient's condition from torsion of the spermatic cord.

Acute Disease↗
PubMed1996

Lack of mutations in epithelial sodium channel beta-subunit gene in human subjects with hypertension.

OBJECTIVE: To investigate a possible role for mutations of the epithelial sodium channel in patients with essential hypertension. DESIGN: A cross-sectional study screening essential hypertension patients and normotensive controls for the presence of a genetic abnormality in the epithelial sodium channel beta-subunit in the Japanese population. SETTING: An institutional teaching hospital. PATIENTS AND PARTICIPANTS: Ninety Japanese patients with essential hypertension and 51 normotensive controls were investigated. The hypertensive patients were consecutive samples from our hypertension clinics. It was required that they had had a previous history of systolic blood pressure higher than 160 mmHg or diastolic higher than 95 mmHg. Secondary hypertension was excluded by clinical presentation or appropriate laboratory examinations. Normotensive subjects were patients visiting our outpatient clinics without evidence or a history of hypertension. It was required that they had systolic blood pressures less than 160 mmHg and diastolic blood pressures less than 90 mmHg, and that they were aged above 60 years. INTERVENTIONS: Genomic DNA from each subject was purified from whole blood and was used as the template for polymerase chain reaction amplification of the carboxy-terminal portion of the epithelial sodium channel beta-subunit. Amplified DNA segments were screened for genetic mutations by direct sequencing. MAIN OUTCOME MEASURE: Genetic mutations of the epithelial sodium channel beta-subunit. RESULTS: No significant genetic mutation was detected in any of the hypertensive and normotensive subjects, except for a polymorphism found in three subjects (two hypertensives and one normotensive). CONCLUSION: Mutations of the carboxy-terminal portion of the epithelial sodium channel beta-subunit were not identified in an unselected cohort of patients with essential hypertension from the Japanese community.

Adult↗
PubMed1996

Rapid isolation of anopheline mosquito eye-colour mutants, based on larval colour change.

A method is presented for the rapid isolation of eye-colour mutants in anopheline mosquitoes based on their inability to undergo a background-stimulated morphological colour change. For application of this method, larval mosquitoes, whose grandfathers had been mutagenized, were reared in black containers and examined with the naked eye en masse during the third or fourth instar. The vast majority of larvae became dark-coloured; however, rare exceptional pale larvae were observed and examined individually microscopically. Approximately half of the pale types examined were eye-colour mutants. By this method, seven sex-linked mutations in the mosquito Anopheles gambiae s.s. were easily isolated. Additional existing anopheline eye-colour mutants in An.gambiae and An.stephensi were tested and were found to be unable to undergo colour change. Several applications of this simple technique are suggested.

Animals↗
PubMed1996

Circulating intercellular adhesion molecule-1 and E-selectin in patients with acute coronary syndrome.

To characterize the role of circulating intercellular adhesion molecules (ICAM-1) and E-selectin in patients with acute coronary syndrome, serum levels of ICAM-1 and E-selectin were measured by enzyme-linked immunosorbent assay (ELISA). Group 1 comprised 17 patients with acute myocardial infarction; group 2 included 17 patients with unstable angina; and group 3 included 19 control subjects. These 53 patients all had prolonged chest pain within 24 h and all underwent coronary angiography. Group 1 and 2 patients had significant coronary artery disease, while group 3 had normal coronary arteries. Blood samples were collected at the emergency department before antiplatelet agents were given. Serum levels of 1CAM-1 were higher in group 1 and 2 (383 +/- 27 and 337 +/- 11 ng/mL, respectively) as compared with group 3 (282 +/- 18 ng/mL) (group 1 vs 3, p<0.01; group 2 vs 3, p<0.05). The serum levels of ICAM-1 were not significantly different between group 1 and 2. Serum levels of E-selectin in group 1, 2, and 3 were 58 +/- 8, 51 +/- 4, and 58 +/- 5 ng/mL, respectively. The serum levels of E-selectin showed no significant difference among the three groups. In conclusion, serum levels of ICAM-1 were elevated in patients with acute coronary syndrome within 24 h, while the E-selectin levels did not change significantly. This finding suggests that adhesion molecule may play an important role in the postrolling process of leukocyte-endothelial cell interaction in acute coronary syndrome.

Aged↗
PubMed1996

Kinetic properties of glutamate receptor channels in cultured embryonic Drosophila myotubes.

Glutamate receptor channels are ubiquitous agonist-gated channels. Pharmacologically they are classified into several subtypes but may have common fundamental channel properties. To build foundation for future molecular biological and genetic studies, we studied kinetics of the glutamate receptor channel in embryonic Drosophila myotubes in culture using the patch clamp technique. There were many brief lasting channel events together with prolonged ones. Brief events were frequently observed in low concentrations whereas the frequency of prolonged events increased with agonist concentrations. Long openings (> 5 ms) were often interrupted by brief closures, most of which lasted less than 100 mu s, thus showing a bursting behavior. At all agonist concentrations, the burst duration was fitted with three exponential components (brief, intermediate and long). The mean duration of the long component increased linearly with the glutamate concentration. The mean closed time and number of brief closures per ms within long bursts were independent of agonist concentration. The mean burst durations of the brief (30-250 mu s) and intermediate component (300-1050 mu s) did not change significantly with agonist concentration. The closing episodes within bursts were rare in the brief and intermediate burst components. The ratio of the fractional areas of the brief or intermediate and long burst components increased linearly with agonist concentration in the log-log plot with a slope of one. These findings suggest that the brief and intermediate components are due to singly-liganded openings and the long component is the result of doubly-liganded openings.

Animals↗
PubMed1996

Pefloxacin-induced arthropathy in an adolescent with brain abscess.

We present a case of pefloxacin-induced arthropathy in a 15-year-old patient with brain abscess. Six joints were involved, of which the right elbow joint was most severely affected. Magnetic resonance imaging of the right elbow revealed joint effusion, and bone scintigraphy showed increased tracer uptake which was still present in the follow-up bone scans.

Adolescent↗
PubMed1996

Moist wound healing.

The optimum wound environment to enhance wound healing is a balance of nutrition, hypoxia, and removal of debris in an occlusive moist environment. With increasing knowledge of the healing process and the variety of dressings available, the end result of any wound management will be an expedited wound healing with maximum patient comfort.

Alginates↗
PubMed1996

Unpredictability of triphenyltetrazolium chloride in staining irreversible ischaemia-reperfusion injury in the skeletal muscle of rats.

OBJECTIVE: To find out whether pale staining with triphenyltetrazolium chloride (TTC) in skeletal muscle of rat hindlimbs which had been subjected to ischaemia-reperfusion definitely indicated irreversible tissue damage. DESIGN: Laboratory study. SETTING: University hospital, Taiwan. MATERIAL: 77 Female Wistar rats. INTERVENTIONS: Ischaemia of one hindlimb was caused by wrapping of a tourniquet above knee joint for 1.5 (n = 14). 2 (n = 15), 2.5 (n = 17), 3 (n = 17) or 4 (n = 14) hours. Each ischaemic group was divided into three subgroups to receive nil, 1 or 1.5 hours reperfusion, respectively. Gastrocnemius and soleus muscles were excised bilaterally. MAIN OUTCOME MEASURES: TTC reduction in the ischaemic limbs presented as a percentage of the opposite control limb measured by a spectrophotometric assay. Density of red formazan deposition in the ischaemic limbs assessed by microscopic examination of the TTC histochemical stain in the 3 hour ischaemic group. RESULTS: In the 2, 2.5, and 3 hour ischaemic groups the TTC reduction in the ischaemic limbs after 1.5 hours reperfusion increased significantly as compared with that with one hour reperfusion (p < 0.01 in each case). The density of red formazan deposition in the muscle after 3 hours ischaemia and 1.5 hours reperfusion was significantly higher than that of only 1 hour of reperfusion. CONCLUSION: Lack of TTC staining does not necessarily represent irreversible ischaemia-reperfusion injury of the skeletal muscle in rats.

Animals↗