Search PubMed⌕ Search

Biomedical subjects

H M Chung

Publications and source records attributed to H M Chung.

At least 19 recordsLinked to original sources
PubMed2007

A preliminary report of brain edema in patients with uremia at first hemodialysis: evaluation by diffusion-weighted MR imaging.

BACKGROUND AND PURPOSE: The dynamics of brain-water content associated with hemodialysis in patients with severe azotemia remains obscure. To investigate whether either interstitial or cytotoxic edema is responsible for dialysis disequilibrium syndrome (DDS), we used diffusion-weighted MR imaging (DWI) to measure the apparent diffusion coefficient (ADC), which is sensitive for detecting tissue water dynamics. METHODS: Eight consecutive patients with end stage renal disease (ESRD) and blood urea nitrogen level of more than 100 mg/dL (160.9 +/- 53.1 mg/dL) were recruited. Conventional MR images, DWI, and clinical manifestations were obtained before and after the 1st hemodialysis. The ADC values were determined for regions of normal-appearing gray and white matter and for regions of hyperintensity of white matter on T2-weighted MR imaging. RESULTS: Foci of bright areas of white matter were found in all patients on T2-weighted images. The ADC values of the patients with ESRD, in white matter and gray matter before and after hemodialysis, were greater than those of the healthy controls (P < .005). Regarding the impact of hemodialysis, the ADC of frontal lobe white matter increased significantly after hemodialysis (1.09 +/- 0.11 versus 1.03 +/- 0.11, P = .036). We did not find the specific area of brain edema reported in posterior leukoencephalopathy and the osmotic demyelination syndrome. CONCLUSIONS: These results suggest that severe azotemia in end stage renal disease leads to interstitial brain edema reflected as increased ADC, and the further increased ADC reflects that edema associated with 1st hemodialysis is interstitial rather than cytotoxic in nature.

Adult↗
PubMed2004

Tuberculosis in patients with end-stage renal disease.

OBJECTIVE: To elucidate the clinical manifestations and risk factors of the mortality rate in uraemic patients with tuberculosis (TB) infection. DESIGN: We retrospectively analysed 62 patients with uraemia and active tuberculosis who were admitted to our hospital from 1990 through 2000. The patients were followed up for 2 years after discharge or until death. RESULTS: There were 43 men and 19 women, with a mean age of 63 +/- 13 years. Extra-pulmonary TB was noted in 51.6%. The peritoneum and pleura were the two most common organs involved. Fever of unknown origin was the most common manifestation (77.4%). The corrected serum Ca2+ level of the patients was >10.5 mg/dl in 46.8%. C-reactive protein >6 mg/dl and leukocytosis (white blood cell count >10,000/mm3) at presentation were noted in more than half of the patients. A reversed serum albumin/globulin ratio and leukocytosis were found to be associated with mortality rate. CONCLUSION: More than half of the TB infections in patients with end-stage renal disease presented with extra-pulmonary involvement. Fever of unknown origin, reversed serum albumin/globulin ratio, and unexplained hypercalcaemia in maintenance dialysis patients suggested the possibility of tuberculosis.

Age Distribution↗
PubMed2001

Increased expression and localization of a serine protease inhibitor, protease nexin-1 (PN-1), in the ovary and uterus during implantation in rat.

Protease nexin-1 (PN-1) is a serine protease inhibitor (serpin) that inactivates several proteases, including thrombin, urokinase, plasminogen activators (PA), and plasmin. It also plays a role in regulating proteolytic activity generated by PA system. PN-1 is known to be involved in tissue remodeling, cellular invasiveness, matrix degradation, and tumor growth. However, the role of PN-1 in female reproductive tracts, such as the uterus, ovary, and oviduct, during pregnancy is not known. The present study was designed to investigate the changes of PN-1 mRNA level and localization in the tracts during implantation and early pregnancy by using reverse transcription (RT)-polymerase chain reaction (PCR) and in situ hybridization. We found that PN-1 mRNA levels were coordinately regulated during early pregnancy in a stage- and tissue-specific manner, such that an increased expression of PN-1 gene appeared at the time of the implantation period in the uterus and ovary. Both the uterus and ovary synthesized PN-1 mRNA and their maximal PN-1 expression occurred on Day 6.5 postcoitum (p.c.). On 13.5 days of pregnancy, PN-1 level was low in the uterus and ovary. On the other hand, PN-1 mRNA in the oviduct did not show after 6.5 days of pregnancy. It appears that PN-1 mRNA in the uterus and ovary was highly regulated during early pregnancy, which might have an important role in implantation of rat blastocysts. PN-1 was localized in endometrial stromal cells of the uterus and in granulosa cells of the unstimulated primary follicles in the ovary during periimplantation period. Also, PN-1 mRNA expression was higher at implantation period than that at nonimplantation period of pregnancy. In conclusion, PN-1 is expressed in female reproductive tracts and highly regulated during implantation and early pregnancy.

Amyloid beta-Protein Precursor↗
PubMed2001

Nephrogenic adenoma associated with cytomegalovirus infection of the ureter in a renal transplant patient: presentation as ureteral obstruction.

Nephrogenic adenoma (NA), a rare benign lesion of the urinary tract, is widely accepted to be a metaplastic reaction due to urothelial injury. It mainly occurs in the urinary bladder and rarely in the ureter. Renal transplant recipients are prone to the development of NA. However in those patients, NA was diagnosed exclusively in the bladder. Herein, we present the--to our knowledge--first case of NA involving a transplanted ureter. A 42-year-old female kidney transplant recipient suffered hematuria, oliguria, and acute renal failure and presented with ureteral obstruction and hydronephrosis of the renal transplant. To our surprise, evidence of cytomegalovirus (CMV) infection of the NA was demonstrated using special immunohistochemical staining. The findings in this case raise the possibility that CMV infection, as an irritant of the ureteral epithelium, may be an etiological factor of NA.

Adenoma↗
PubMed2001

Expression of the Xenopus homologue of the receptor for activated C-kinase 1 (RACK1) in the Xenopus embryo.

We have isolated the Xenopus homologue of the receptor for activated C-kinase 1 (RACK1), whose amino acid sequence shows significant similarity with other vertebrate RACK1s. XRACK1 is a maternally expressed gene and its zygotic expression is detected in the antero-dorsal region and dorsal midline in the late neurula. At tailbud stage, rather diffuse staining is seen in the somite and head. Later, XRACK1 mRNA is expressed highly in ventrally migrating abdominal muscle anlagen, where it remains expressed during subsequent stages.

Amino Acid Sequence↗
PubMed2001

Cryopreservation of ICR mouse oocytes: improved post-thawed preimplantation development after vitrification using Taxol, a cytoskeleton stabilizer.

OBJECTIVE: To establish an effective cryopreservation method. DESIGN: In vitro model study. SETTING: Infertility Medical Center, Pochon CHA University. ANIMAL(S): Four-week-old ICR mice superovulated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin. INTERVENTION(S): Vitrified-thawed oocytes were fertilized and subsequently cultured in vitro. MAIN OUTCOME MEASURE(S): Post-thawed development, chromosome/spindle normalities, and blastocyst quality. RESULT(S): More cumulus-enclosed oocytes were fertilized and developed to the 8-cell stage after vitrification and thawing than denuded oocytes. However, cryopreserved oocytes of both types had lower spindle and chromosome normalities than fresh oocytes, which resulted in reduced developmental competence after thawing. The addition of 1 microM of Taxol, a cytoskeleton stabilizer, to vitrification solution greatly promoted the blastocyst formation of vitrified-thawed oocytes, compared with no addition (24.0% vs. 58.6%). No difference in blastocyst quality, which was evaluated by blastomere and inner cell mass cell numbers and inner cell mass cell per trophoblast ratio, was found between fresh oocytes and oocytes vitrified with Taxol. CONCLUSION(S): A vitrification solution consisting of 5.5 M ethylene glycol, 1.0 M sucrose, 10% fetal bovine serum, and 1 microM Taxol greatly improved post-thawed development of vitrified oocytes.

Animals↗
PubMed2001

Establishment of an animal embryo culture system containing various embryotropins and its efficacy for culturing ICR mouse one-cell embryos derived in vivo or in vitro.

OBJECTIVE: To develop an effective ICR mouse embryo culture medium. DESIGN: In vitro model study. SETTING: University-affiliated hospital. ANIMALS: Four-week-old, superovulated mice. INTERVENTION(S): In vivo- or in vitro-derived one-cell embryos were cultured in preimplantation-1 medium (P-1). MAIN OUTCOME MEASURE(S): Preimplantation development. RESULT(S): In vivo-derived embryos were cultured in BSA-containing P-1, to which one of the following substances was added: [1] no addition, [2] amino acids (aa), [3] aa+hemoglobin (hb), [4] aa+hb+cysteine (cys), [5] aa+hb and glucose (glu) added at the four-cell, or [6] aa+hb and glu+cys added at the four-cell stage. More (P<0.05) blastocysts developed after aa or aa+hb addition than after no addition, and glu addition to such medium further stimulated the formation (54%). In P-1 with aa+glu, the addition of 1 microg/mL hb was optimal. Additional improvement of blastocyst formation (78%) was achieved by ethylenediaminetetraacetic acid (EDTA), supplementation and bovine serum albumin replacement with polyvinyl alcohol (PVA) did not inhibit the development. P-1 supplemented with aa, hb, glu, EDTA, and PVA also supported the development of in vitro-derived embryos (70%). CONCLUSION(S): A modified P-1 medium was developed, and it supported the development of both in vivo- and in vitro-derived ICR mouse embryos.

Amino Acids↗
PubMed2001

Nicastrin is required for Presenilin-mediated transmembrane cleavage in Drosophila.

The transmembrane glycoprotein Nicastrin was identified in a complex with the multipass membrane protein Presenilin. Presenilin mediates transmembrane cleavage of single-pass transmembrane proteins with short extracellular domains, including the ligand-activated form of the receptor Notch and beta-amyloid precursor protein (beta-APP). Transmembrane cleavage of Notch is essential for signal transduction, and transmembrane cleavage of beta-APP generates pathogenic amyloid peptides implicated in Alzheimer's disease. Here, we investigate the requirement for Nicastrin in Presenilin-mediated transmembrane cleavage. We show that, in Drosophila, loss of Nicastrin activity blocks the accumulation of Presenilin associated with the apical plasma membrane, abolishes Presenilin-dependent cleavage of the transmembrane domains of Notch and beta-APP, and abrogates Notch signal transduction.

Amyloid Precursor Protein Secretases↗
PubMed2001

Acute oxalate nephropathy after ingestion of star fruit.

Acute oxalate nephropathy associated with ingestion of star fruit (carambola) has not been reported before. We report the first two cases. These patients developed nausea, vomiting, abdominal pain, and backache within hours of ingesting large quantities of sour carambola juice; then acute renal failure followed. Both patients needed hemodialysis for oliguric acute renal failure, and pathologic examinations showed typical changes of acute oxalate nephropathy. The renal function recovered 4 weeks later without specific treatment. Sour carambola juice is a popular beverage in Taiwan. The popularity of star fruit juice is not compatible with the rare discovery of star fruit-associated acute oxalate nephropathy. Commercial carambola juice usually is prepared by pickling and dilution processes that reduce oxalate content markedly, whereas pure fresh juice or mild diluted postpickled juice for traditional remedies, as used in our cases, contain high quantities of oxalate. An empty stomach and dehydrated state may pose an additional risk for development of renal injury. To avoid acute oxalate nephropathy, pure sour carambola juice or mild diluted postpickled juice should not be consumed in large amounts, especially on an empty stomach or in a dehydrated state.

Acute Kidney Injury↗
PubMed2001

Acute oxalate nephropathy induced by star fruit in rats.

In this study, we intend to establish a connection between star fruit and acute oxalate nephropathy and also investigate predisposing factors for its development. Male Sprague-Dawley rats of 180 to 200 g were assigned to four groups; namely, control, experimental, fasting, and water-deprivation groups. The former two groups were subjected to both fasting and water deprivation, whereas the latter two groups were subjected to either fasting or water deprivation, respectively. Except for tap water for controls, the remaining groups were administered 4 mL/100 g of body weight of sour star fruit juice with an oxalate concentration of 2.46 g/dL. After these procedures, serial measurement of serum creatinine levels and kidney pathological examination were performed. Peak serum creatinine levels in the control, experimental, fasting, and water-deprivation groups were 0.50 +/- 0.04, 1.46 +/- 0.26, 0.68 +/- 0.20, and 0.52 +/- 0.08 mg/dL, respectively. The experimental group had a greater peak serum creatinine level (P < 0.05). Mean serum creatinine levels of the experimental group days 0, 1, 2, 3, 4, and 5 were 0.43 +/- 0.03, 1.11 +/- 0.18, 1.31 +/- 0.27, 1.16 +/- 0.28, 0.8 +/- 0.26, and 0.82 +/- 0.28 mg/dL, respectively. Mean serum creatinine levels days 1 to 3 were greater than that day 0 (P < 0.05). Pearson's correlation analysis of peak serum creatinine level and kidney weight for the experimental group showed a significant correlation (R = 0.75; P < 0.05; n = 9). In addition to typical changes of oxalate nephropathy, kidney pathological examination showed many refractile oxalate crystals with all rainbow colors under polarized light microscopy in the experimental group. In conclusion, sour star fruit with abundant oxalate contents could cause acute oxalate nephropathy in rats under the conditions of fasting and water deprivation.

Acute Kidney Injury↗
PubMed2001

Rhabdomyolysis: an unusual feature with mushroom poisoning.

Rhabdomyolysis resulting from mushroom poisoning previously has been unreported in the literature. We present an outbreak of Russula subnigricans poisoning with rhabdomyolysis. The most severely ill patient presented with rhabdomyolysis, severe electrolyte disturbance (hyperkalemia, hypocalcemia), respiratory failure, acute renal failure, pulmonary edema, ventricular tachycardia, and circulatory shock. Mycotoxin may be the cause of rhabdomyolysis. In areas where mushroom gathering is common, mushroom poisoning should be included in the differential diagnosis of rhabdomyolysis.

Female↗
PubMed2001

Tuberculosis in maintenance dialysis patients.

In this investigation, we tried to find the incidence and characteristics of tuberculosis (TB) in dialysis patients previously found only in a small number of cases. We collected the cases of newly diagnosed TB patients in Taiwan during 1997. Simultaneously, all dialysis patients were collected and matched with the TB cases to identify the dialysis patients who had also contracted TB. The annual incidence of the dialysis population was 493.4/100,000, 6.9 times that of the general population (71.1/100,000). The annual incidence for the male dialysis population was 573.3, the incidence was 479.2 for the female dialysis population. The incidence for the general population was 97.1 and 43.7/100,000, respectively. Although the 1-year mortality rate due to TB (1.7 vs. 1.9%, p > 0.05) was similar in both populations, the non-TB mortality was much higher in the dialysis population than that in the general population (25.6 vs. 11.1%, p < 0.05). Finally, the 1-year mortality rate of dialysis patients with TB is 3.3 times higher than that in dialysis patients without TB (27.3 vs. 8.3%, p < 0.05). The findings suggest that uremia modifies the behavior of TB, jeopardizes female and younger dialysis patients, poses a higher risk of extrapulmonary dissemination, and predicts a higher overall mortality.

Age Factors↗
PubMed2001

The long-term effects of single peritonitis episodes on peritoneal equilibration test results in continuous ambulatory peritoneal dialysis patients.

The present study evaluates the long-term effects of single peritonitis episodes on peritoneal equilibration test (PET) results in continuous ambulatory peritoneal dialysis (CAPD) patients. Twenty-five patients (10 men, 15 women) with a mean age of 37.4 +/- 18.7 years were enrolled in this study because all had uneventful peritoneal dialysis periods for more than one year after a first peritonitis episode. Data from a total of 69 PETs were available [25 from before the first peritonitis episode (initial PET), 23 within 1 year after the episode (1-year PET), and 21 within 1-2 years after the episode (2-year PET)]. The changes in the PET results were evaluated using the dialysate-to-plasma ratio of creatinine (D/PCr) and the dialysate-to-instilled glucose ratio (D4/D0) after a 4-hour dwell. The mean values of D/PCr and D4/D0 showed no statistically significant changes between the initial PETs, 1-year PETs, and 2-year PETs. However, analysis of the results for patients with culture-positive peritonitis (n = 17) revealed significant changes in the mean values of D/PCr and D4/D0 between the initial PET and the 2-year PET (0.63 +/- 0.06 vs 0.70 +/- 0.09, p = 0.01; and 0.41 +/- 0.05 vs 0.37 +/- 0.06, p = 0.04, respectively). The long-term effect of a definite bacterial peritonitis episode seems to be an increase in small-molecule transport. In patients with culture-negative peritonitis, the episode had less impact on peritoneal transport.

Adult↗
PubMed2000

Freezing immature oocytes.

The establishment of a long-term preservation system for mammalian oocytes is important for the development of both biological and medical sciences. A number of efforts have been made to develop this system. In human reproductive medicine, the development of an oocyte cryopreservation system can improve the efficacy of the current assisted reproductive technology (ART) for infertile patients with severe reproductive disorders. In this article, the technical development of cryopreservation programs for human oocytes and its biological background were reviewed. Clinical outcome after the use of this technology was further introduced.

Cell Culture Techniques↗
PubMed2000

Effect of betulinic acid on intracellular-free Ca(2+) levels in Madin Darby canine kidney cells.

The effect of betulinic acid, an anti-tumor and apoptosis-inducing natural product, on intracellular-free levels of Ca(2+) ([Ca(2+)](i)) in Madin Darby canine kidney (MDCK) cells was examined by using fura-2 as a Ca(2+) dye. Betulinic acid caused significant increases in [Ca(2+)](i) concentration dependently between 25 and 500 nM with an EC(50) of 100 nM. The [Ca(2+)](i) signal was composed of an initial gradual rise and a plateau. The response was decreased by removal of extracellular Ca(2+) by 45+/-10%. In Ca(2+)-free medium, pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca(2+) pump inhibitor) abolished 250 microM betulinic acid-induced [Ca(2+)](i) increases. Conversely, pretreatment with betulinic acid only partly inhibited thapsigargin-induced [Ca(2+)](i) increases. Addition of 3 mM Ca(2+) induced a [Ca(2+)](i) increase after pretreatment with 250 nM betulinic acid in Ca(2+)-free medium for 5 min. This [Ca(2+)](i) increase was not altered by the addition of 20 microM SKF96365 and 10 microM econazole. Inhibiting inositol 1,4,5-trisphosphate formation with the phospholipase C inhibitor U73122 (2 microM) abolished 250 nM betulinic acid-induced Ca(2+) release. Pretreatment with 10 microM La(3+) inhibited 250 nM betulinic acid-induced [Ca(2+)](i) increases by 85+/-3%; whereas 10 microM of verapamil, nifedipine and diltiazem had no effect. In Ca(2+) medium, pretreatment with 2.5 nM betulinic aid for 260 s potentiated 10 microM ATP and 1 microM thapsigargin-induced [Ca(2+)](i) increases by 33+/-3% and 45+/-3%, respectively. Trypan blue exclusion revealed that acute exposure of 250 nM betulinic acid for 2-30 min decreased cell viability by 6+/-2%, which could be prevented by pretreatment with 2 microM U731222. Together, the results suggest that betulinic acid induced significant [Ca(2+)](i) increases in MDCK cells in a concentration-dependent manner, and also induced mild cell death. The [Ca(2+)](i) signal was contributed by an inositol 1,4, 5-trisphosphate-dependent release of intracellular Ca(2+) from thapsigargin-sensitive stores, and by inducing Ca(2+) entry from extracellular medium in a La(3+)-sensitive manner.

Adenosine Triphosphate↗
PubMed2000

in vitro development of porcine enucleated oocytes reconstructed by the transfer of porcine fetal fibroblasts and cumulus cells.

In the pig little information is available on cytoplasmic events during the reprogramming of oocytes reconstructed with somatic nuclei. The present study was conducted to determine the developmental potential of porcine cumulus cells (CC) and fetal fibroblasts (FF) after they were transferred into enucleated oocytes. Non-quiescent FF were fused to the enucleated oocytes using electrical pulse, whereas CC were directly injected into the oocytes. Transferred nuclei from both CC and FF underwent premature chromosome condensation (PCC), nuclear swelling and pronucleus formation. The remodeled oocytes developed to the mitotic and 2-cell stage at 18 to 24 h after nuclear transfer. The pattern of nuclear remodeling was similar regardless of the sources of karyoplasts or nuclear transfer methods. However, using FF, 24% of nuclear transferred embryos developed to the morula or blastocyst stage, whereas only 8% of those using CC developed to the morula or blastocyst stage. These results suggest that porcine oocyte cytoplasm can successfully reprogram somatic cell nuclei and support the development of nuclear transferred embryos to the blastocyst stage.

Animals↗
PubMed2000

Expression of enhanced green fluorescent protein (EGFP) and neomycin resistant (Neo(R)) genes in porcine embryos following nuclear transfer with porcine fetal fibroblasts transfected by retrovirus vector.

In this study, we demonstrated expression of enhanced green fluorescent protein (EGFP) and neomycin resistant (Neo(R)) genes in porcine embryos following nuclear transfer from porcine fetal fibroblasts (PFFs) transduced with the EGFP and Neo(R) genes by retrovirus-mediated infection. Nuclear transfer of the nonstarved transfected PFF into enucleated oocytes was accomplished by cell to cell fusion. Out of 188 porcine eggs reconstructed by nuclear transfer, 116 (61.7%) eggs cleaved and 25 (13.3%) developed to morula and blastocyst stages. Of these 25 morulae and blastocysts, 25 (100%) embryos emitted green fluorescence. Expression of the both EGFP and Neo(R) genes was detected as early as the 2-cell stage. As determined by EGFP gene expression, mosaicism was not observed in any embryo. These results suggest that porcine oocytes reconstructed by nuclear transfer with transfected PFFs can successfully develop to the blastocyst stage. In addition, this approach might be applicable to the production of transgenic pigs with complex genetic modifications.

Animals↗