Biomedical subjects

C C Chang

Publications and source records attributed to C C Chang.

At least 91 records · Page 5Linked to original sources

PubMed2001

Diabetic ketoacidosis and hypogonadotropic hypogonadism in association with transfusional hemochromatosis in a man with beta-thalassemia major.

We report a 23-year-old man with beta-thalassemia major and transfusional hemochromatosis, which manifested as diabetic ketoacidosis and hypogonadotropic hypogonadism. This unusual presentation of diabetic ketoacidosis in hemochromatosis has rarely been reported. Magnetic resonance imaging of the abdomen showed decreased signal intensity in the liver, spleen, and pancreas. In addition, the pituitary gland also showed heterogeneous low signal intensity, compatible with hemochromatosis. He was treated with insulin supplements and pulsatile human chorionic gonadotropin administration. Clinical improvement was noted after hormone replacement. Intensive iron chelation therapy was given to prevent cardiac complications, and to restore his gonadal function. During follow-up, the patient experienced improvement in libido and sexual potency.

Adult↗

PubMed2001

Preoperative diagnosis and localization of aldosterone-producing adenoma by adrenal venous sampling after administration of metoclopramide.

BACKGROUND AND PURPOSE: Adrenal venous sampling is the most reliable test to distinguish aldosterone-producing adenoma (APA) from idiopathic hyperaldosteronism (IHA). The diagnostic accuracy can be improved by administration of adrenocorticotropin to minimize pulsatile secretion of aldosterone. Metoclopramide (MCP), a dopamine antagonist, can increase aldosterone secretion promptly without affecting cortisol secretion. This study investigated the diagnostic accuracy of adrenal venous sampling after MCP injection for the preoperative diagnosis and localization of APA. METHODS: Prospective diagnosis and adrenalectomy was based on adrenal venous sampling in 23 patients with a diagnosis of primary aldosteronism. Plasma aldosterone concentrations from adrenal veins and the inferior vena cava were measured before and 30 minutes after intravenous administration of 10 mg MCP. The ratio of bilateral adrenal venous aldosterone concentrations after MCP was used for diagnosis as follows: a ratio greater than 5 indicated APA, less than 3 indicated IHA, and 3-5 indicated an intermediate diagnosis. RESULTS: Catheterization of the right adrenal vein was unsuccessful in three patients. Twelve of 13 patients with an aldosterone ratio greater than 5 after MCP underwent unilateral adrenalectomy, and APA was confirmed in 11 of these patients. One patient with an intermediate diagnosis also had surgically confirmed APA. Six patients had a ratio less than 3. Before MCP administration, 10 of 13 patients with APA had a ratio greater than 5, and three patients had a ratio between 3 and 5; one patient with IHA had a ratio greater than 5. MCP improved the diagnosis of APA to an accuracy of 92% (12/13). Correct diagnosis of APA based on computerized tomography (CT) was 85% (11/13). There was discordance between the findings of adrenal venous sampling and CT in four of 20 patients. CONCLUSIONS: Administration of MCP to stimulate aldosterone secretion during adrenal venous sampling can improve the accuracy of differential diagnosis between APA and IHA.

Adenoma↗

PubMed2001

Zona-free oocyte fertilized with intracytoplasmic sperm injection and underwent further division: case report and literature review.

The zona pellucida (ZP) plays a protective role during fertilization and early embryonic development. It is related to sperm binding, the acrosome reaction, prevention of polyspermic fertilization, and holding blastomeres together before the morular stage. Zona-free oocytes are accidentally encountered. If these oocytes are healthy, they can be fertilized normally by intracytoplasmic sperm injection (ICSI). We reported on a couple with male infertility undergoing oocyte retrieval after ovarian hyperstimulation. Before the ICSI procedure, cumulus cells surrounding the oocytes were removed, which resulted in one oocyte escaping from its ZP. The zona-free oocyte was fertilized normally with ICSI and developed to the 8-cell stage. We observed that the zona-free zygote had the ability to further divide, despite its loose contact. The zona-free embryo was transferred with other zona-intact embryos, but the implantation failed. We conclude that zona-free oocytes can be rescued, fertilized with ICSI, and cultured for further transfer or cryopreservation.

Adult↗

PubMed2001

Catalysis of ACAT may be completed within the plane of the membrane: a working hypothesis.

Two ACAT sharing protein sequence homology near their C termini have been identified. Both proteins may span the endoplasmic reticulum (ER) membrane several times. There is good evidence implicating the role of ACAT1 in macrophage foam cell formation, and ACAT2 in intestinal cholesterol absorption. On the other hand, the functional roles of ACAT1 and ACAT2 in the VLDL or chylomicron assembly process are less clear. It is possible that both enzymes are able to form lipid droplets (which are present in the cytoplasm), and participate in lipoprotein assembly (which occurs in the ER lumen). To link the site of ACAT catalysis with its function, we propose that part of the ACAT catalytic site may reside within the lipid bilayer, allowing catalysis to be completed within the plane of the membrane. Cholesteryl esters (CE) produced in situ may burst into cytoplasmic lipid droplets, carrying phospholipid monolayers as their outer coats. In cells engaged in lipoprotein assembly and secretion, CE in the bilayer may be recognized by the specific protein microsomal triacylglycerol transfer protein (MTP), reaching out from the lumenal side of the membrane. MTP then lipidates the growing apolipoprotein B (apoB) chain with CE and TG during the early stages of apoB lipoprotein assembly.

Acetyl Coenzyme A↗

PubMed2001

Endoscopic mucosal resection with a cap-fitted endoscope for early gastric carcinoma with focal submucosal invasion in a patient with decompensated liver cirrhosis.

Prognosis for patients with early gastric cancer who undergo gastric resection is far better than that for patients with advanced disease. However, patients with advanced liver cirrhosis may not be suitable for general anesthesia and major surgery. We used a less invasive endoscopic mucosal resection (EMR) with a cap-fitted endoscope to resect an early gastric cancer in a 58-year-old male with decompensated liver cirrhosis. Although postoperative pathology revealed that the tumor had focal invasion to the submucosa, the patient had an uneventful course and was well during 4 years' follow-up. This method may be effective for the treatment of early gastric cancer with focal submucosal invasion when patients are not suitable for major surgery.

Adenocarcinoma↗

PubMed2001

Methimazole-induced pulmonary hemorrhage associated with antimyeloperoxidase-antineutrophil cytoplasmic antibody: a case report.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis has been recently recognized in Graves' disease patients treated with antithyroid drugs. We describe the case of an 18-year-old girl who developed antimyeloperoxidase ANCA (MPO-ANCA)-positive vasculitis manifesting as a skin lesion and hemoptysis with hypoxic respiratory failure after taking methimazole. An open lung biopsy was consistent with acute capillaritis. Both skin and sural nerve biopsy showed lymphocytic vasculitis. Administration of steroid and plasmapheresis produced a good clinical response.

Adolescent↗

PubMed2001

Value of ICD-9 coded chief complaints for detection of epidemics.

To assess the value of ICD-9 coded chief complaints for early detection of epidemics, we measured sensitivity, positive predictive value, and timeliness of Influenza detection using a respiratory set (RS) of ICD-9 codes and an Influenza set (IS). We also measured inherent timeliness of these data using the cross-correlation function. We found that, for a one-year period, the detectors had sensitivity of 100% (1/1 epidemic) and positive predictive values of 50% (1/2) for RS and 25% (1/4) for IS. The timeliness of detection using ICD-9 coded chief complaints was one week earlier than the detection using Pneumonia and Influenza deaths (the gold standard). The inherent timeliness of ICD-9 data measured by the cross-correlation function was two weeks earlier than the gold standard.

Disease↗

PubMed2000

Renormalization group analysis for thermal turbulent transport.

In this study, we continue with our previous renormalization group analysis of incompressible turbulence, aiming at determination of various thermal transport properties. In particular, the temperature field T is considered a passive scalar. The quasinormal approximation is assumed for the statistical correlation between the velocity and temperature fields. A differential argument leads to derivation of the turbulent Prandtl number Pr(t) as a function of the turbulent Peclet Pe(t) number, which in turn depends on the turbulent eddy viscosity nu(t). The functional relationship between Pr(t) and Pe(t) is comparable to that of Yakhot et al. [Int. J. Heat Mass Transf. 30, 15 (1987)] and is in close consistency with direct-numerical-simulation results as well as measured data from experiments. The study proceeds further with limiting the operation of renormalization group analysis, yielding an inhomogeneous ordinary differential equation for an invariant thermal eddy diffusivity sigma. Simplicity of the equation renders itself a closed-form solution of sigma as a function of the wave number k, which, when combined with a modified Batchelor's energy spectrum for the passive temperature T, facilitates determination of the Batchelor constant C(B) and a parallel Smagorinsky model and the model constant C(P) for thermal turbulent energy transport.

Journal Article↗

PubMed2000

Monocyte-derived CD1a+ and CD1a- dendritic cell subsets differ in their cytokine production profiles, susceptibilities to transfection, and capacities to direct Th cell differentiation.

We describe a phenotypically and functionally novel monocyte-derived dendritic cell (DC) subset, designated mDC2, that lacks IL-12 synthesis, produces high levels of IL-10, and directs differentiation of Th0/Th2 cells. Like conventional monocyte-derived DC, designated mDC1, mDC2 expressed high levels of CD11c, CD40, CD80, CD86, and MHC class II molecules. However, in contrast to mDC1, mDC2 lacked expression of CD1a, suggesting an association between cytokine production profile and CD1a expression in DC. mDC2 could be matured into CD83+ DC cells in the presence of anti-CD40 mAbs and LPS plus IFN-gamma, but they remained CD1a- and lacked IL-12 production even upon maturation. The lack of IL-12 and CD1a expression by mDC2 did not affect their APC capacity, because mDC2 stimulated MLR to a similar degree as mDC1. However, while mDC1 strongly favored Th1 differentiation, mDC2 directed differentiation of Th0/Th2 cells when cocultured with purified human peripheral blood T cells, further indicating functional differences between mDC1 and mDC2. Interestingly, the transfection efficiency of mDC2 with plasmid DNA vectors was significantly higher than that of mDC1, and therefore mDC2 may provide improved means to manipulate Ag-specific T cell responses after transfection ex vivo. Taken together, these data indicate that peripheral blood monocytes have the capacity to differentiate into DC subsets with different cytokine production profiles, which is associated with altered capacity to direct Th cell differentiation.

Antigen-Presenting Cells↗

PubMed2000

On-line monitoring trihalomethanes in chlorinated water by membrane introduction-fast gas chromatography mass-spectrometry.

An analytical method based on membrane introduction and fast gas chromatography-mass spectrometry (GC-MS) has been developed for the on-line monitoring of trihatomethanes (THMs) in chlorinated drinking water. The coupling of membrane introduction with fast GC-MS offers the advantage of membrane introduction as an on-line sampling device and fast GC-MS as a separation and identification method. While maintaining the on-line monitoring characteristic of traditional membrane introduction mass spectrometry (MIMS), the difficulty of distinguishing CHCl3 and CHBrCl2 in MIMS was overcome by rapid GC separation and MS analysis. Water permeated across the membrane affected the analysis of CHBr2Cl and CHBr3. A method based on controlling the injection temperature and injection time has been developed to overcome the moisture problem. This method is simple and less time consuming than the conventional moisture removing method. Under typical operating conditions, the sampling rate was about 20 samples h(-1) capable of on-line monitoring THMs in chlorinated drinking water. The detection limits of this system were found to be about 2 ppt, 4 ppt, 4 ppt, and 8 ppt for CHCl3 CHBrCl2, CHBr2Cl, and CHBr3, respectively.

Chlorine↗

PubMed2000

Immunological quantitation and localization of ACAT-1 and ACAT-2 in human liver and small intestine.

By using specific anti-ACAT-1 antibodies in immunodepletion studies, we previously found that ACAT-1, a 50-kDa protein, plays a major catalytic role in the adult human liver, adrenal glands, macrophages, and kidneys but not in the intestine. Acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity in the intestine may be largely derived from a different ACAT protein. To test this hypothesis, we produced specific polyclonal anti-ACAT-2 antibodies that quantitatively immunodepleted human ACAT-2, a 46-kDa protein expressed in Chinese hamster ovary cells. In hepatocyte-like HepG2 cells, ACAT-1 comprises 85-90% of the total ACAT activity, with the remainder attributed to ACAT-2. In adult intestines, most of the ACAT activity can be immunodepleted by anti-ACAT-2. ACAT-1 and ACAT-2 do not form hetero-oligomeric complexes. In differentiating intestinal enterocyte-like Caco-2 cells, ACAT-2 protein content increases by 5-10-fold in 6 days, whereas ACAT-1 protein content remains relatively constant. In the small intestine, ACAT-2 is concentrated at the apices of the villi, whereas ACAT-1 is uniformly distributed along the villus-crypt axis. In the human liver, ACAT-1 is present in both fetal and adult hepatocytes. In contrast, ACAT-2 is evident in fetal but not adult hepatocytes. Our results collectively suggest that in humans, ACAT-2 performs significant catalytic roles in the fetal liver and in intestinal enterocytes.

Adolescent↗

PubMed2000

Restoration of gap junctional intercellular communication by caffeic acid phenethyl ester (CAPE) in a ras-transformed rat liver epithelial cell line.

Caffeic acid phenethyl ester (CAPE), an active ingredient of honeybee propolis, has been identified as having anti-inflammatory, anti-viral and anti-cancer properties. Since the deficiency of gap junctional intercellular communication (GJIC) has been shown to be a characteristic of most cancer cells, this study was designed to test the hypothesis that the anti-carcinogenic activity of CAPE might be related to its ability to restore GJIC in tumorigenic GJIC-deficient cells (WB-ras2 cells). The results showed that CAPE restored GJIC, phosphorylation of connexin 43 (Cx43) and its normal localization on the plasma membrane in WB-ras2 cells after 3 days at 5 microg/ml concentration. Additionally, CAPE inhibited growth in soft agar and decreased the protein level of p21(ras). The results are consistent with the hypothesis that the anti-cancer mechanism of CAPE may be mediated by its ability to restore GJIC.

Animals↗

PubMed2000

Purification and characterization of neutral sphingomyelinase from Helicobacter pylori.

Phospholipase activities of human gastric bacterium, Helicobacter pylori, are regarded as the pathogenic factors owing to their actions on epithelial cell membranes. In this study, we purified and characterized neutral sphingomyelinase (N-SMase) from the superficial components of H. pylori strains for the first time. N-SMase was purified 2083-fold with an overall recovery of 37%. The purification steps included acid glycine extraction, ammonium sulfate precipitation, CM-Sepharose, Mono-Q, and Sephadex G-75 column chromatography. Approximate molecular mass for the native N-SMase was around 32 kDa. When N-omega-trinitrophenylaminolauryl sphingomyelin (TNPAL-SM) was used as a substrate, the purified enzyme exhibited a K(m) of 6.7 microM and a V(max) of 15.6 nmol of TNPAL-sphingosine/h/mg of protein at 37 degrees C in 50 mM phosphate-buffered saline, pH 7.4. N-SMase reaches optimal activity at pH 7.4 and has a pI of 7.15. The enzyme activity is magnesium dependent and specifically hydrolyzed sphingomyelin and phosphatidylethanolamine. The enzyme also exhibits hemolytic activity on human erythrocytes. According to Western blot analysis, a rabbit antiserum against purified N-SMase from H. pylori cross-reacted with SMase from Bacillus cereus. Sera from individuals with H. pylori infection but not uninfected ones recognizing the purified N-SMase indicated that it was produced in vivo. In enzyme-linked immunosorbent assays, the purified N-SMase used as an antigen was as effective as crude protein antigens in detecting human antibodies to H. pylori.

Antibodies, Bacterial↗

PubMed2000

Regulation of plastid rDNA transcription by interaction of CDF2 with two different RNA polymerases.

The plastid genome is known to be transcribed by a plastid-encoded prokaryotic-type RNA polymerase (PEP) and by a nucleus-encoded phage-type RNA polymerase (NEP). The spinach plastid rrn operon promoter region harbours three different, overlapping promoters. Two of them are of the prokaryotic type. The third promoter is a non-consensus-type NEP promoter. We separated three different transcriptional activities from spinach chloroplasts: PEP, the phage-type RNA polymerase NEP-1, and a third, hitherto undescribed transcriptional activity (NEP-2). NEP-2 specifically transcribes the rrn operon in the presence of the transcription factor CDF2. CDF2 was previously shown to recruit PEP to the rrn promoter to repress transcription. Together, our results suggest the existence of a third RNA polymerase in plastids and a mechanism of rDNA transcriptional regulation that is based on the interaction of the transcription factor CDF2 with two different transcriptional systems.

Blotting, Western↗

PubMed2000

Longitudinal doppler sonographic measurements of vascular impedance in the central and peripheral spiral arteries throughout pregnancy.

PURPOSE: We assessed vascular impedance in the spiral arteries in the central and peripheral placental bed throughout uncomplicated pregnancies. METHODS: Transabdominal color Doppler sonography was used to measure the pulsatility index (PI), resistance index (RI), and peak systolic velocity in the central and peripheral spiral arteries in 94 women with uncomplicated singleton pregnancies. Sonographic examinations took place approximately every 5 weeks from 10 to 40 weeks' menstrual age. RESULTS: PI, RI, and peak systolic velocity were not different in the central versus the peripheral segments of the spiral arteries. The PI and RI values of central spiral arteries after 25 weeks' menstrual age. The PI and RI values of peripheral arteries decreased after 20 weeks' menstrual age. CONCLUSIONS: Additional subjects are needed to clarify changes in the impedance of central and peripheral spiral arteries over the course of normal and complicated pregnancies.

Adult↗

PubMed2000

Modulation of cell-cell communication in the cause and chemoprevention/chemotherapy of cancer.

Chemopreventive or chemotherapeutic agents have been those that either kill cancer cells to a differential degree over the non-cancer cells or those chemicals that either block the induction of tumors in carcinogen-treated animals or retard transplanted tumors in animals. Carcinogenesis is a multi-stage, multi-mechanism process, involving the irreversible alteration of a stem cell ("initiation"), followed by the clonal proliferation of the initiated cell ("promotion"). To develop a strategy for intervention with chemoprevention/chemotherapeutic chemicals, the basic mechanism(s) of carcinogenesis must be understood. Gap junction intercellular communication (GJIC) regulates cell growth, differentiation, apoptosis and adaptive functions of differentiated cells. Normal cells have functional GJIC while cancer cells do not. Tumor promoters and oncogenes inhibit GJIC, while anti-tumor promoter and anti-oncogene drugs can reverse the down-regulation of GJIC. Transfection of gap junction genes (connexins) has been shown to reverse the tumorigenic phenotype. If prevention/treatment of cancer is to occur, prevention of the chronic down regulation of GJIC by tumor promoters in non-tumorigenic but initiated cells or the up-regulation of GJIC in stably down-regulated GJIC in tumor cells must occur to prevent or to treat cancers.

Anticarcinogenic Agents↗

PubMed2000

Gap junctions and the regulation of cellular functions of stem cells during development and differentiation.

In multicellular organisms, the role of gap junction intercellular communication (GJIC) in the regulation of cell proliferation, cell differentiation, and apoptosis is becoming increasingly recognized as one of the major cellular functions from the start of the fertilized egg, through normal development of the embryo and fetus, to the sexual maturation of the adult and ultimately to the maintenance of health of the aging adult. Given that the function of this membrane-associated protein channel is to synchronize electrotonic or metabolic functions, differential regulation of function at the transcriptional, translational, and posttranslational levels of a family of highly evolutionarily conserved genes (connexins) needs to be considered. Both inherited mutations and environmental modulation of GJIC could, in principle, affect the function of gap junctions to control cell proliferation, cell differentiation, and apoptosis, thereby leading to a wide variety of pathologies. We review a few techniques used to characterize the ability of stem and progenitor cells to perform GJIC.

Animals↗

PubMed2000

Fetal renal volume assessment by three-dimensional ultrasonography.

OBJECTIVE: This study was undertaken to measure fetal renal volume by means of three-dimensional ultrasonography and to use those data to establish the accurate constant and formula for fetal renal volume assessment with two-dimensional ultrasonography. STUDY DESIGN: Singleton fetuses between 15 and 40 weeks' gestation were included. The volumes of both fetal kidneys were measured with three-dimensional ultrasonography. Three fetal renal diameters (largest anteroposterior, transverse, and longitudinal diameters) were measured, and the constant of the fetal renal volume formula was calculated. Linear regression curves were made for each kidney from the fetal renal volume, the three diameters, and the constant. RESULTS: A total of 112 fetuses were included. The following fetal renal volume formula was established: Fetal renal volume = Constant (R) x Largest anteroposterior diameter (x) x Largest transverse diameter (y) x Largest longitudinal diameter (z). The volumes, the three diameters, and the constants appeared different between the right and left kidneys but not statistically significantly so. CONCLUSION: Three-dimensional ultrasonography is useful in assessing fetal renal volume. The fetal renal volume formula makes possible accurate measurements of fetal renal volume by two-dimensional ultrasonography.

Female↗