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Biomedical subjects

H C Chen

Publications and source records attributed to H C Chen.

At least 325 records · Page 18Linked to original sources
PubMed1994

Adrenal adenoma with primary aldosteronism in a child: a case report.

Primary aldosteronism caused by an aldosterone-producing adrenal adenoma was documented in an 11-year-old girl who presented with persistent hypertension, headache, tinnitus and hypokalemia. Elevated plasma aldosterone concentration (PAC) (45.5 ng/dl) and suppressed plasma renin activity (PRA) (< 0.3 ng/ml/hrs) were detected. Saline infusion test and postural test helped to confirm the diagnosis. The tumor site was localized by magnetic resonance imaging (MRI). Surgical removal of the tumor yielded dramatic improvement in blood pressure; PAC and PRA returned to normal range. This rare case illustrates the feasibility of recognition and localization of adrenal adenoma in children. The high cure rate by surgical excision warrants careful screening of hypertensive patients with this entity.

Adenoma↗
PubMed1994

[Effect of panaxadiol saponin (PDS) on phorbol ester induced change of protein kinase C activity in cardiomyocytes].

Partially purified protein kinase C and protein kinase A were separately incubated with various concentrations of PDS (1-1000 micrograms.ml-1) for 10 min in vitro. The results indicate that protein kinase C activity was inhibited in a dose-dependent manner by PDS, but type I and type II protein kinase A were not. In cardiomyocytes preincubated with PDS (250, 500, 1000 micrograms.ml-1) for 10 min, PMA-induced decrease of cytosol protein kinase C activity and increase of membrane protein kinase C activity were greatly inhibited in the same manner. These results suggest that PDS not only inhibited protein kinase C in vitro, but also inhibited activation of protein kinase C in cardiomyocytes.

Animals↗
PubMed1994

Clinical observation of neonatal gastrointestinal perforation.

BACKGROUND: Gastrointestinal perforation is an infrequent occurrence in neonates. Experience in its management is presented, while also attempting to analyze the factors affecting outcome. METHODS: From 1983 to 1992, 31 neonates with gastrointestinal perforation were treated at Taichung Veterans General Hospital. The medical records of these patients were reviewed thoroughly. In the meantime, Mann-Whitney U and Yates' correction chi square tests were used to analyze the factors predicting the outcomes. RESULTS: There were 21 males and 10 females, among whom 16 were premature births. The median age at diagnosis was 5 day; half (16/31) had occurred during the first 5 days of life. Abdominal distension was the most common manifestation (87%). Hemograms at admission showed leukopenia in 32% (10/31) and thrombocytopenia in 40% (8/20) of the patients. Metabolic acidosis was present in 46% (13/28) of the patients. Peritoneal fluid and preoperative blood cultures were positive in 71% (17/24) and 50% (13/26) of the patients, and both of them had Gram-negative enterobacteriacea as the most common pathogen. The overall mortality rate was 58%. The highest mortality rate was associated with gastric perforation (100%), followed by small bowel (50%) and colon (50%) perforations. The predominant cause of perforation was necrotizing enterocolitis (14/31), with the most common site the terminal ileum (16/29). Four patients with necrotizing enterocolitis had multiple perforations. Others who underwent surgery showed single perforation. The major cause of death in those patients who received operation was sepsis (8/13). An initial arterial pH value higher than 7.25, and surgical procedure performed within two days after disease onset may predict a favorable outcome (p < 0.01). CONCLUSIONS: Gastrointestinal perforation is a life-threatening complication in neonates. A better survival rate can be obtained by cooperation among neonatologists, pediatric surgeons and the nursing staff taking care of these high risk babies.

Chi-Square Distribution↗
PubMed1994

Congenital duodenal web in late infancy and childhood: a report of two cases.

Congenital duodenal webs are rare lesions, usually detected during early infancy because of signs of high intestinal obstruction. The occasional patient escapes both symptoms and detection until adolescence or adulthood. This report concerns two cases of congenital duodenal web at different ages and with different clinical manifestations. Case 1, a six-month-old male, was admitted because of abdominal distention and vomiting. Case 2, a 13-year-old boy, was referred here for further evaluation of recurring seizure attacks, elevated blood urea nitrogen and creatinine and hyponatremia. Duodenotomy and excision of the web performed for both patients. Complete amelioration of all symptoms was then observed at Outpatient Clinic follow-up for one year.

Adolescent↗
PubMed1994

Retinal blood flow changes during pregnancy in women with diabetes.

PURPOSE: To study retinal blood flow (RBF) during pregnancy in subjects with and without diabetes and to relate the changes to progression in diabetic retinopathy. METHODS: RBF in a major temporal retinal vein was measured, where possible, during all three trimesters (T1 to T3) and the postpartum period (PP) using laser Doppler velocimetry (measuring velocity [V]) and monochromatic fundus photographs (measuring diameter [D]). RESULTS: In the subjects without diabetes (n = 19), no significant change in RBF was demonstrated. V was significantly greater in T3 than in PP (P = 0.01). D was significantly smaller in T1 to T3 than in PP (P < or = 0.01). RBF in the subjects with diabetes was significantly higher in T2 and T3 than in PP (P < 0.05). V increased from T1 to T2 (P = 0.04) and decreased from T2 to PP (P = 0.001) and from T3 to PP (P = 0.002). The only significant change in D was a smaller value in T1 than in PP (P = 0.003). However, it was only those subjects whose DR progressed (n = 11) who had a significant increase in RBF during pregnancy (P = 0.0001). CONCLUSIONS: These data suggest that the hyperdynamic circulation present in pregnancy led to compensatory retinal vessel constriction (autoregulation) in the group without diabetes; this was largely absent in the patients with diabetes, with resultant increase in retinal blood flow associated with worsening retinopathy. This finding lends further support to the hypothesis that increased retinal blood flow is a pathogenic mechanism for diabetic retinopathy.

Adult↗
PubMed1994

Isolation and characterization of the promoter region of human nm23-H1, a metastasis suppressor gene.

Allelic deletions in the nm23, a metastasis suppressor gene, are known to occur in neuroblastomas, breast and colorectal carcinomas. Down-regulation of nm23 expression has been reported in various rodent and human tumor cells with high metastasis phenotype. Colorectal tumors showed overexpression of nm23. To elucidate the regulatory mechanisms of nm23, we isolated, cloned and sequenced the presumptive regulatory DNA fragment spanning the 5' region of the human nm23-H1 gene. The region's nucleotide sequence shows the presence of motifs typical for transcriptional elements such as TFIID, AP-1 and CTF/NF1. A common transcription initiation site is located at -136 upstream from the first ATG codon in placenta tissue, in breast, colorectal, prostate tumor cell lines and in primary colorectal tumor. Multiple transcription start sites were identified in tumor cell lines and colorectal tumor. When the promoter element was linked to a reporter gene, chloramphenicol acetyltransferase (CAT) and transfected in human 2fTGH cells, strong CAT activity was detected, which also showed that the presence of AP-1 and CTF/NF1 elements are essential for promoter activity. A detailed study of the structure and function of the promoter element of the nm23-H1 gene will help in understanding the regulatory mechanisms of nm23 expression and its role in tumor progression, especially in metastasis.

Base Sequence↗
PubMed1994

Reconstruction of four damaged or destroyed ipsilateral fingers with free toe-to-hand transplantations.

Three patients with traumatic partial or complete loss of all ipsilateral digits, excluding the thumb, were reconstructed with free microvascular toe transplantations for all involved digits. In two cases, two pairs of combined second and third toe transplantations were utilized; in the third case, four separate toes were employed. Clinical follow-up was 8 1/2 years, 2 years, and 1 2/3 years. Detailed functional analysis was performed. All patients except the first had initially undergone reconstruction of only two digits and had requested a second procedure to transfer two additional toes. While reconstruction of the thumb and two opposing digits is adequate in most cases, selected patients may benefit from the additional two digits, especially with respect to improving hook grip.

Adolescent↗
PubMed1994

Congenital diaphragmatic hernia.

BACKGROUND: The management of congenital diaphragmatic hernia (CDH) remains a subject of controversy. With the objective to achieve a better future survival rate, clinical analysis of 14 cases during a 10-year period was done. METHODS: From 1983 to 1992, 14 cases with CDH were treated at Taichung Veterans General Hospital. The medical records of these patients were reviewed thoroughly. In the meantime, Mann-whitney U and Fisher's exact tests were used to analyze the factors predicting the outcomes. RESULTS: The overall mortality rate was 36%. Bochdalek hernia represented the most common defect in those patients who were operated upon (10/13, 77%). Ipsilateral pulmonary hypoplasia was present in five patients, four of whom died. Unilateral diaphragm agenesis was noted in two cases and both expired postoperatively. Initial arterial pH < 7.2, PaCO2 > 60 mmHg and early onset of symptoms may predict a poor outcome. There were no significant benefits from preoperative stabilization in those patients whose initial arterial pH values were lower than 7.2. CONCLUSIONS: CDH remains a major challenge for pediatricians and pediatric surgeons. Further studies are needed to deal with this frustrating disorder.

Female↗
PubMed1994

Meconium peritonitis in neonates.

BACKGROUND: Meconium peritonitis is a rare occurrence in neonates. Experience in its management is presented, while also attempting to compare present results with previous reports. METHODS: Between 1983 and 1993, 10 patients of meconium peritonitis were studied retrospectively. Clinical pictures, image studies, course and management were reviewed thoroughly. RESULTS: There were seven males and three females, with two premature births. None of these patients had associated cystic fibrosis. The symptoms and signs presented within one week after birth, with abdominal distension being the most common manifestation (90%). Radiographic evidence of intraperitoneal calcified plaques or masses were present in only half of our patients. Surgery was performed in eight, of whom four had primary bowel obstructions. The most common site of bowel perforation was at the terminal ileum (six patients). Two patients who did not receive surgical intervention were diagnosed radiographically and sonographically, and showed cystic type meconium peritonitis. The outcome of these patients has been good except for one who died of sepsis. CONCLUSIONS: The low mortality rate (10%) in this series may depend in part on successful prenatal diagnosis of four patients and, in part, on continuing progress in perinatal intensive care. A better outcome in this potentially fatal disease can thus be anticipated by the cooperation of neonatologists, pediatric surgeons and obstetricians.

Female↗
PubMed1994

Pulmonary sequestration.

BACKGROUND: Pulmonary sequestration is a relatively rare congenital abnormality. It is a cystic mass of nonfunctioning lung tissue which lacks an obvious communication with the tracheobronchial tree and which receives all or most of its arterial blood from anomalous systemic vessels. METHODS: Six patients with intralobar pulmonary sequestration were treated at this Hospital from 1982 to 1993. The two males and four females had ages ranging from 15 years to 56 years. Five of the six patients were symptomatic, with histories of chronic cough, intermittent fever, hemoptysis, and/or pleuric chest pain. The other patient was asymptomatic. Locations of the lesion included the left lower lobe in three, the right lower lobe in two and the right middle lobe in one. RESULTS: All patients received surgical intervention. Lobectomies were performed in five, and segmentectomy in one. There was no postoperative complication or mortality and all have remained asymptomatic during the follow-up period. CONCLUSIONS: A high index of suspicion is the most important element in the diagnosis of pulmonary sequestration. Angiography is mandatory to demonstrate the aberrant arterial supply and the venous drainage of pulmonary sequestration. Surgery should be performed early in order to reduce potentially life threatening obstruction and infection, and hasten the return of normal pulmonary function.

Adolescent↗
PubMed1993

The phosphorylation and DNA binding of the DNA-binding domain of the orphan nuclear receptor NGFI-B.

NGFI-B is an orphan member of the nuclear receptor superfamily encoded by an immediate-early gene. It is rapidly synthesized and phosphorylated in PC12 cells in response to nerve growth factor (NGF) and other agents and is differentially phosphorylated dependent upon the inducing stimulus. The DNA-binding domain (DBD) of NGFI-B has been expressed in bacteria and purified. The purified protein is phosphorylated by protein kinase A or by extracts from NGF-treated PC12 cells. The phosphorylated residues within the DBD have been identified as Ser-340 and Ser-350. The use of mutants in which either or both of these residues were replaced with alanines revealed that phosphorylation of Ser-350, located within the "A box," a motif necessary for DNA binding by NGFI-B, resulted in a decrease in binding to the NGFI-B response element, while phosphorylation of Ser-340 had little or no effect. These findings demonstrate that phosphorylation of a nuclear receptor DBD results in a change in DNA binding and provides another potential mechanism for regulating NGFI-B activity.

Amino Acid Sequence↗
PubMed1993

Isolation of two distinct 3-hydroxysteroid sulfotransferases from the guinea pig adrenal. Evidence for 3 alpha-hydroxy versus 3 beta-hydroxy stereospecificity.

Two physically distinct hydroxysteroid sulfotransferases (HSTs) that demonstrate substrate specificity with respect to the orientation of the ring A 3-hydroxyl group have been isolated from the guinea pig adrenal gland. Nondenaturing liquid-phase isoelectric focusing permitted the separation of the activities, and reverse phase high performance liquid chromatography was used to purify the two proteins to homogeneity. The 3 beta-HST had an apparent molecular mass of 33 kDa and utilized pregnenolone, 17-hydroxypregnenolone, and dehydroepiandrosterone as substrates. The 3 alpha-HST was slightly smaller at 32 kDa and utilized allopregnanolone and androsterone as substrates. The proteins were further distinguished by isoelectric point, immunoreactivity, and tryptic peptide mapping. Peptides isolated from both guinea pig HSTs demonstrated significant amino acid sequence homology (approximately 65% identity) to rat liver HST; however, available sequence data from the two proteins did not yield differences that might account for their stereospecific substrate selectivity. This paper represents the first definitive report demonstrating the existence of discrete HSTs that exhibit substrate specificity based on the stereochemistry of the 3-hydroxyl group.

Adrenal Glands↗
PubMed1993

Purification and characterization of a paired basic residue-specific yeast aspartic protease encoded by the YAP3 gene. Similarity to the mammalian pro-opiomelanocortin-converting enzyme.

Yeast cells express an alternate enzyme encoded by the YAP3 gene which can process pro-alpha-mating factor when this pheromone is overexpressed in KEX2-deficient mutants. The YAP3 gene product is an aspartic protease (YAP3) that cleaves at paired basic residues (Egel-Mittani, M., Flygenring, H.P., and Hansen, M. T. (1990) Yeast 6, 127-137). In this study, the YAP3 gene was overexpressed in the BJ 3501 strain of Saccharomyces cerevisiae. YAP3 was purified to apparent homogeneity using concanavalin A and pepstatin A affinity chromatography. The enzyme was characterized as an M(r) 68,000 glycoprotein with a pH optimum of 4.0-4.5. It was inhibited by pepstatin A and activated by 5 mM Ca2+. YAP3 cleaved at paired basic residues of mouse pro-opiomelanocortin (POMC) to yield adrenocorticotropin (ACTH) and beta-lipotropin (LPH); human beta-LPH to yield beta-endorphin-(1-31), beta-endorphin-(1-29), beta-endorphin-(1-28), gamma-LPH, and beta-melanocyte-stimulating hormone; and bovine N-POMC1-77 to yield gamma 3-melanocyte-stimulating hormone. It also cleaved the tetrabasic residues of ACTH1-39 to yield primarily ACTH1-15 and Lys-Arg-corticotropin-like intermediate lobe peptide. The physical properties, pH optimum, and specificity of YAP3 indicate that it is a homologue of the mammalian POMC-converting enzyme (EC 3.4.23.17), a paired basic residue-specific aspartic protease from bovine pituitary intermediate lobe secretory granules (Loh, Y. P., Parish, D.C., and Tuteja, R. (1985) J. Biol. Chem. 260, 7194-7205).

Adrenocorticotropic Hormone↗
PubMed1993

Mutation in the nm23 gene is associated with metastasis in colorectal cancer.

The human nm23 gene, a candidate metastatic suppressor gene, consists of two genes, nm23-H1 and nm23-H2. The potential mutation in the nm23-H1 gene was examined in colorectal cancer using a reverse transcription polymerase chain reaction amplification followed by DNA sequencing analysis. Genomic alterations in the nm23 gene were also examined by Southern hybridization. Genetic alterations either as a deletion in the coding sequence of nm23-H1 or as an allelic deletion were detected in four among eight colorectal adenocarcinomas associated with metastases in lymph nodes, lung, or liver. No alteration was observed in 12 additional colorectal cancer specimens without metastasis. These results provide first evidence for novel mutation in the nm23 gene and demonstrate a correlation between the mutation in the nm23 gene and metastasis in colorectal oncogenesis which suggests that the nm23 gene plays a role in the causation of metastasis.

Alleles↗
PubMed1993

Protein kinase C phosphorylates Ser152, Ser156 and Ser163 but not Ser160 of MARCKS in rat brain.

MARCKS is one of the major physiological substrates of PKC and was reported to be phosphorylated by PKC at 4 serine residues that are within the CaM-binding region (Graff et al., J. Biol. Chem. 264, 11912, 1989). Using MARCKS from rat brain and a synthetic peptide of 25 amino acids containing all 4 of the serine residues, we investigate the differences in phosphorylation by PKC isozymes I, II and III. Tryptic peptide analysis of PKC phosphorylated MARCKS or peptide, we found 32P was in peptides of (K)S152FK, (R)FS156FK and LS160GFS163FK. Further digestion of LSGFSFK with alpha-chymotrypsin revealed that 32P incorporation occurred only at Ser163 but not at Ser160. The initial rates and stoichiomatry of phosphorylation of Ser152 and Ser156 were twice as those of Ser163 using either one of the three PKC isozymes. These results indicate that in vitro, PKC phosphorylates MARCKS only at three sites, but not at Ser160 as that reported previously, and there was no preferential phosphorylation of MARCKS by either PKC isozyme I, II or III.

Amino Acid Sequence↗
PubMed1993

Functional and esthetic reconstruction of a mutilated hand using multiple toe transfers and iliac osteocutaneous flap: a case report.

With reconstructive microsurgical techniques, some previously hopelessly mutilated hands have become reconstructable. The functional and esthetic results of such hands can be improved to an acceptable degree with through prereconstruction evaluation and planning. This case report demonstrates the approach to reconstruction of a mutilated hand using the following: a pedicle groin flap for soft tissue reconstruction of the first web space and the amputation stump of the thumb; a combined second and third toe transfer for reconstruction of opposable fingers at the amputated index and middle finger stumps; a single second toe for reconstruction of the thumb, and an iliac osteocutaneous flap for reconstruction of the ulnar border of the palm.

Accidents, Occupational↗