Biomedical subjects

J H Chiang

Publications and source records attributed to J H Chiang.

At least 19 recordsLinked to original sources

PubMed2001

Enhanced activity of adenine-DNA glycosylase (Myh) by apurinic/apyrimidinic endonuclease (Ape1) in mammalian base excision repair of an A/GO mismatch.

Adenine-DNA glycosylase MutY of Escherichia coli catalyzes the cleavage of adenine when mismatched with 7,8-dihydro-8-oxoguanine (GO), an oxidatively damaged base. The biological outcome is the prevention of C/G-->A/T transversions. The molecular mechanism of base excision repair (BER) of A/GO in mammals is not well understood. In this study we report stimulation of mammalian adenine-DNA glycosylase activity by apurinic/apyrimidinic (AP) endonuclease using murine homolog of MutY (Myh) and human AP endonuclease (Ape1), which shares 94% amino acid identity with its murine homolog Apex. After removal of adenine by the Myh glycosylase activity, intact AP DNA remains due to lack of an efficient Myh AP lyase activity. The study of wild-type Ape1 and its catalytic mutant H309N demonstrates that Ape1 catalytic activity is required for formation of cleaved AP DNA. It also appears that Ape1 stimulates Myh glycosylase activity by increasing formation of the Myh-DNA complex. This stimulation is independent of the catalytic activity of Ape1. Consequently, Ape1 preserves the Myh preference for A/GO over A/G and improves overall glycosylase efficiency. Our study suggests that protein-protein interactions may occur in vivo to achieve efficient BER of A/GO.

Amino Acid Sequence↗

PubMed2001

The triple-phase CT image appearance of post-irradiated livers.

OBJECTIVE: To evaluate the sequential CT appearance of the liver after hepatic irradiation and to investigate the correlation between CT findings and radiation-induced hepatic injury. MATERIAL AND METHODS: The triple-phase CT images of 18 patients with hepatocellular carcinomas (HCC) after hepatic irradiation were retrospectively reviewed (in total 41 CT studies). The high-dose region within the liver was defined as the area receiving more than 90% of the prescribed irradiation dose. The mean radiation dose was 55.5 Gy. Density changes and patterns of enhancement in the high-dose region were classified as three types: type I, constant low-density change in all phases; type II, low-density change in both pre-contrast and arterial phases, and iso-density change in the portal phase; type III, low- or iso-density change in the pre-contrast phase, low- or high-density change in the arterial phase, and persistent high-density change in the portal phase. The interval between completion of radiotherapy and the CT examinations ranged from 9 to 469 days, with a mean of 147 days. RESULTS: Nine of the 41 CT studies presented with type I, 9 with type II, and 16 with type III CT findings. The mean interval between completion of radiotherapy and the appearance of types I, II, and III CT findings were 74, 183, and 220 days, respectively. The interval was significantly shorter for type I findings than for type II and type III. The difference in interval was not significant between type II and type III. A type I finding with constant low-density change in the high-dose region of the liver was the most common pattern of CT findings within the first 3 months after hepatic irradiation. Either types II or III findings were frequently seen after 3 months. CONCLUSION: The sequential CT appearance and the density changes may indicate correlation with the pathogenesis of veno-occlusive disease.

Adult↗

PubMed2001

Image evaluation of suprazygomatic masticator space lesions.

In order to understand lesions involving the suprazygomatic masticator space (SZMS) demonstrated on computered tomography (CT) or magnetic resonance (MR) images, we collected 45 cases of lesions in SZMS. There were hematomas in 26 cases, tumors in 16 cases, and abscesses in 3 cases. The location of these lesions in compartments of the SZMS and adjacent structures was analyzed. Most commonly hematoma was found in the deep loose connective tissue (80.8%), followed by the superficial dense connective tissue (61.5%). Only 2 SZMS hematoma involved the superficial fat pad. Five patients had air accumulation in the SZMS, and all were in the deep fat pad and with maxillary sinus fracture. Of the sixteen cases which were tumors, 12 were extended from adjacent structures, and four were primary tumor. In cases of tumor, compartments of SZMS involved most frequently were temporal muscles (15 of 16 cases), followed by deep fat pad (8 of 16 cases). The connective tissue layer of SZMS is a communication pathway for superficial spread of infection, hematoma, or tumor invasion to or from the scalp and face. Compartments of deep fat pad and temporal muscle are also pathways for the spread of disease to or from the face, intracranium and orbit. The primary tumors in infratemporal fossa and SZMS are rare. Malignant tumors in SZMS usually come from surrounding spaces.

Adolescent↗

PubMed2001

Sequential MR studies of a patient with white matter disease presenting psychotic symptoms: ADEM versus single-episode MS.

Acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) are both demyelinating white matter disorders. It is difficult to differentiate ADEM from single episode MS because of the similar clinical presentation, cerebral spinal fluid (CSF) analysis, histological finding and magnetic resonance image (MRI) appearance. We report an ADEM case with unusual clinical presentations of predominant psychiatric symptoms, and relatively long disease course. Initially, we were not able to distinguish it from single episode MS. By means of sequential MR images followed up 2 years and spectroscopy studies, and the dramatic clinical improvement after corticosteroid therapy, ADEM was diagnosed as the disease entity of this patient. In this case report we will present the MR findings of this patient and discuss the differentiation between the ADEM and MS.

Adult↗

PubMed2001

Resection of triple synchronous tumors--gastric adenocarcinoma, gallbladder adenocarcinoma and stromal tumor of the stomach.

We herein report a rare case of triple synchronous tumors: gastric adenocarcinoma, gallbladder adenocarcinoma and stromal cell tumor of stomach, which were resected in the same operation. A 72-year-old male patient suffered from poor appetite and epigastric pain that radiated to his back for one month. Upper gastrointestinal endoscopy showed a gastric ulcer measuring 1.5 cm at the prepyloric area, which was proven to be adenocarcinoma by biopsy. A second tumor was found in the gallbladder, measuring 3 cm, by ultrasonography. On computed tomography, a third tumor about 2.5 cm in size was recognized posterior to the gastric high body and anterior to the pancreas. Given the presence of three tumors, he underwent a radical subtotal gastrectomy with Billroth-II gastrojejunostomy and simultaneous cholecystectomy. Pathological findings revealed gastric adenocarcinoma, gallbladder adenocarcinoma and stromal cell tumor of the stomach. The postoperative course was smooth.

Adenocarcinoma↗

PubMed2001

A progressive growing inflammatory pseudotumor of the liver.

Inflammatory pseudotumors of the liver are very rare, and their etiology and pathogenesis remain unclear. The diagnosis is often difficult to make because these masses often mimic other lesions such as primary neoplasms, metastases or liver abscesses. Herein, we report a rare case of progressive growing hepatic pseudotumor in a 47-year-old man. The patient presented with body weight loss and general malaise. A series of radiological examinations showed the progressive growth of the hepatic tumor from 3.5 cm to 10.0 cm in diameter within 8 months. He underwent a right lobectomy of the liver, and the final diagnosis was proven by pathology. There were no complications in the post-operative course.

Granuloma, Plasma Cell↗

PubMed2000

Cloning and characterization of a new member of the Nudix hydrolases from human and mouse.

Proteins containing the Nudix box "GX(5)EX(7)REUXEEXGU" (where U is usually Leu, Val, or Ile) are Nudix hydrolases, which catalyze the hydrolysis of a variety of nucleoside diphosphate derivatives. Here we report cloning and characterization of a human cDNA encoding a novel nudix hydrolase NUDT5 for the hydrolysis of ADP-sugars. The deduced amino acid sequence of NUDT5 contains 219 amino acids, including a conserved Nudix box sequence. The recombinant NUDT5 was expressed in Escherichia coli and purified to near homogeneity. At the optimal pH of 7, the purified recombinant NUDT5 catalyzed hydrolysis of two major substrates ADP-ribose and ADP-mannose with K(m) values of 32 and 83 microM, respectively; the V(max) for ADP-mannose was about 1.5 times that with ADP-ribose. The murine NUDT5 homolog was also cloned and characterized. mNudT5 has 81% amino acid identity to NUDT5 with catalytic activities similar to NUDT5 under the optimal pH of 9. Both NUDT5 and mNudT5 transcripts were ubiquitously expressed in tissues analyzed with preferential abundance in liver. The genomic structures of both NUDT5 and mNudT5 were determined and located on human chromosome 10 and mouse chromosome 2, respectively. The role of NUDT5 in maintaining levels of free ADP-ribose in cells is discussed.

Adenosine Diphosphate Ribose↗

PubMed2000

Prospective case-controlled trial of adjuvant chemotherapy after resection of hepatocellular carcinoma.

Recurrence of hepatocellular carcinoma (HCC) after curative hepatic resection is frequent and is an important factor adversely influencing long-term survival. The role of postoperative chemotherapy in the reduction of tumor recurrence rate is still controversial. During the period of 1992-1995 a series of 49 patients who underwent curative resection of HCC and had at least one risk factor of tumor recurrence were followed in this prospective study. Patients were allocated to adjuvant chemotherapy and control groups. Twenty-four patients received a combination of low dose intravenous epirubicin (20 mg/m2) and mitomycin (5 mg) monthly for seven courses starting 5 to 6 weeks after surgery. Twenty-five patients had no adjuvant treatment. The disease-free and overall survivals were compared for the two groups. A total of 154 courses of chemotherapy were given to the 24 patients. The chemotherapy-related side effects were mild and tolerable with no mortality. At a median follow-up of 39 months (range 9-71 months), 9 patients in the adjuvant chemotherapy group and 16 patients in the control group developed tumor recurrence. The respective 1-, 2-, 3-, and 5-year disease-free survival rates were 75%, 67%, 63%, and 63% for patients in the adjuvant chemotherapy group and 68%, 42%, 37%, and 32% for patients in the control group (p = 0.0575). The 1-, 2-, 3-, and 5-year overall survival rates were 100%, 96%, 77%, and 72% in the adjuvant chemotherapy group and 92%, 67%, 63%, and 51% in the control group (p = 0.0746). In conclusion, postoperative adjuvant chemotherapy using the present regimen has a tendency to reduce tumor recurrence rate and may improve long-term survival for high risk patients.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

Genes involved in the determination of the rate of inversions at short inverted repeats.

BACKGROUND: Not all of the enzymatic pathways involved in genetic rearrangements have been elucidated. While some rearrangements occur by recombination at areas of high homology, others are mediated by short, often interrupted homologies. We have previously constructed an Escherichia coli strain that allows us to examine inversions at microhomologies, and have shown that inversions can occur at short inverted repeats in a recB,C-dependent fashion. RESULTS: Here, we report on the use of this strain to define genetic loci involved in limiting rearrangements on an F' plasmid carrying the lac genes. Employing mini-Tn10 derivatives to generate insertions near or into genes of interest, we detected three loci (rmuA,B,C) that, when mutated, increase inversions. We have mapped, cloned and sequenced these mutator loci. In one case, inactivation of the sbcC gene leads to an increase in rearrangements, and in another, insertions near the recE gene lead to an even larger increase. The third gene involved in limiting inversions, rmuC, has been mapped at 86 min on the E. coli chromosome and encodes a protein of unknown function with a limited homology to myosins, and some of the SMC (structural maintenance of chromosomes) proteins. CONCLUSIONS: This work presents the first example of an anti-mutator role of the sbcC,D genes, and defines a new gene (rmuC) involved in DNA recombination.

Chromosome Inversion↗

PubMed2000

Hepatocellular carcinoma presenting as a pyogenic liver abscess in a patient with hemochromatosis.

Primary hemochromatosis is rare in Taiwan. Hepatocellular carcinoma (HCC) is endemic in Taiwan, but HCC with initial presentation as pyogenic liver abscess is unusual. We report a case of HCC presenting as pyogenic liver abscess in a hemochromatotic patient with cirrhosis. The patient underwent hepatectomy and had a smooth postoperative course. Unfortunately, he died of pneumonia eight months after surgery. HCC should be considered in the differential diagnosis in hemochromatotic patients with a pyogenic liver abscess.

Aged↗

PubMed2000

High resolution MRI of adrenal glands in patients with primary aldosteronism.

BACKGROUND: We studied the role of high-resolution magnetic resonance imaging (MRI) of the adrenal glands using a surface coil in patients with primary aldosteronism to differentiate aldosterone-producing adenomas (APA) from idiopathic hyperplasia of the adrenal gland (IHA). The data obtained were used to decide on surgical or nonsurgical treatment for patients. METHODS: High-resolution MRI with SE T1WI, FSE T2WI and paired in- and out-phase images of the adrenal glands of 41 patients with clinically documented primary aldosteronism were collected. The images were reviewed in comparison with other differentiating tests. RESULTS: Nineteen of the 41 patients were diagnosed with APA on MRI. Surgical and pathologic proof of APA was obtained in 10 cases and solitary macronodular hyperplasia was found in one case. Among these 11 cases, there were no false positive findings on MRI, while correct detectability of high-resolution computerized tomography (CT) was 62.5% (5/8); for adrenal venous sampling, it was 37.5% (3/8); and for NP-59 adrenal scanning, it was 42.9% (3/7). In eight cases with biochemically favored APA and no surgical proof, MRI and CT showed the same lesion detection rate, while there was no concordance with venous sampling, and concordance of only 33.3% (2/6) for adrenal scanning. In the remaining 22 patients without focal lesions on MRI, there was poor concordance among the four test modalities, with frequently conflicting results. CONCLUSIONS: In patients with definitive results of noninvasive biochemical tests for APA, and positive findings of unilateral, focal adrenal lesion on MRI or CT, unilateral adrenalectomy may be justified without further tedious and invasive examinations. CT should still be the first screening test; however, high-resolution MRI is a useful diagnostic supplement for patients with strong clinical evidence of APA and negative or equivocal findings on CT.

Adrenal Glands↗

PubMed2000

Cavernous sinus gas.

Gas within the cavernous sinus is an unusual finding. We report three patients who demonstrated gas in the cavernous sinus on computerized tomography (CT). The clinical information of these patients was reviewed for the possible source of the gas and the symptoms induced by the gas. Cavernous sinus gas was seen in two patients with sphenoid sinus fracture and in one patient after intravenous fluid infusion. None of the patients had symptoms referable to the cavernous sinus gas, but one patient had a grave prognosis due to trauma. Identification of cavernous sinus gas on CT and correlation with the clinical information is mandatory for further management.

Adult↗

PubMed2000

Aberrant cervical carotid artery.

Aberrant cervical carotid artery is an uncommon anomaly. Because this anomaly can lie in close proximity to the midline of the posterior part of the pharynx, it poses a significant risk during both major pharyngeal tumor resection and less extensive procedures such as tonsillectomy, adenoidectomy and palatopharyngoplasty. Five cases of aberrant cervical carotid artery were encountered and diagnosed using computerized tomography. In all five cases, the anomalous finding did not correlate with the presenting symptoms. Computerized tomographic images of these cases are provided. A review of the literature and the embryology of the aberrant carotid artery are presented. Awareness of the anomaly by radiologists and surgeons is essential to avoid accidental injury to the vessel during surgery.

Adult↗

PubMed2000

Double-balloon technique for embolization of carotid cavernous fistulas.

Embolization of a carotid cavernous fistula (CCF) by means of a detachable balloon is an established method for treating CCFs while preserving a patent parent internal carotid artery (ICA). However, failure to embolize the CCF may occur on a few occasions, such as when the balloon cannot pass through the fistula into the cavernous sinus by blood flow, or when the inflated balloon in the cavernous sinus retracts to the carotid artery. Under these circumstances, the ICA may have to be sacrificed in order to treat the CCF. Herein we describe a double-balloon technique for embolization of a CCF. By applying this technique, we successfully treated nine of 11 CCFs, without compromise of the parent ICA when the conventional one-balloon technique failed.

Balloon Occlusion↗

PubMed2000

Fat in the cerebral falx.

BACKGROUND: Fat within the cerebral falx is commonly encountered in our daily practice but has never been characterized and reported. The purpose of this study was to determine the incidence of fat within the cerebral falx and to identify its clinical features. METHODS: The cerebral falx was prospectively imaged in 1,570 consecutive brain computed tomographic scans and its features characterized. Cerebral magnetic resonance imaging was done in some patients. RESULTS: Of the 1,570 cases studied, 115 revealed a small amount of fat in the cerebral falx. This fat had a purely negative Hounsfield value. It produced a high signal on both T1- and T2-weighted magnetic resonance images. There was no calcified component. The fat was seen most commonly in aged patients. No related symptoms were noted. CONCLUSIONS: Among the patients studied, fat in the cerebral falx had an incidence of 7.3%. It is an incidental finding in adults and requires no further evaluation or treatment.

Adolescent↗

PubMed1999

Paraneoplastic syndromes in patients with hepatocellular carcinoma in Taiwan.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most common malignancy in Taiwan. Some patients may manifest paraneoplastic syndromes during the clinical course of the disease. In this study, the authors evaluated the clinical significance of these paraneoplastic syndromes, compared the prevalence of these syndromes between cases of hepatitis B virus (HBV)-related and hepatitis C virus (HCV)-related HCC, and estimated significant predictors associated with the syndromes. METHODS: Clinical data on 1197 HCC patients, including age, gender, Child-Pugh score, survival time, laboratory data (including liver biochemistry, hepatitis markers, and serum alpha-fetoprotein [AFP]), and tumor features (including tumor size, portal vein thrombosis, and histologic pictures), were retrospectively reviewed. RESULTS: A total of 232 of 1197 patients (19.4%) had paraneoplastic syndromes. HCC patients with paraneoplastic syndromes had significantly higher serum AFP; higher rates of initial main portal vein thrombosis, metastasis, and bilobal tumor involvement; larger tumor volume; and shorter survival than those without these syndromes. Patients with HBV-related HCC had a significantly higher prevalence of paraneoplastic syndromes than patients with HCV-related HCC (20.1% vs. 11.2%, P = 0.005). In a stepwise multivariate logistic regression analysis, AFP >50,000 ng/mL and tumor volume >30% were significant predictive variables associated with the presence of paraneoplastic syndromes in HCC patients. CONCLUSIONS: HCC patients with paraneoplastic syndromes usually had higher levels of serum AFP and larger tumor volumes than those without. Patients with HBV-related HCC had a significantly higher prevalence of paraneoplastic syndromes than those with HCV-related HCC.

Aged↗

PubMed1999

Manifestations of hypercholesterolaemia, hypoglycaemia, erythrocytosis and hypercalcaemia in patients with hepatocellular carcinoma: report of two cases.

BACKGROUND: Hypercholesterolaemia, hypoglycaemia, hypercalcaemia and erythrocytosis, are well-known paraneoplastic manifestations in patients with hepatocellular carcinoma (HCC). Hepatocellular carcinoma patients manifesting with two or three paraneoplastic manifestations have been previously reported. However, HCC patients presenting with four paraneoplastic syndromes have not been previously reported. METHODS AND RESULTS: This manuscript describes two HCC patients who manifested with hypercholesterolaemia, hypoglycaemia, hypercalcaemia and erythrocytosis during their clinical course. Erythrocytosis appeared early when HCC was diagnosed and declined to within normal range after optimal therapy for HCC. Hypercholesterolaemia manifested initially after the diagnosis in case 1, declined to within normal range after lobectomy and was re-elevated after tumour recurred. With disease progression, hypercalcaemia and hypoglycaemia occurred 1-3 months after diagnosis and the both patients subsequently died several days later. CONCLUSIONS: Similar features found in both patients were large tumour burden, high serum alpha-fetoprotein level and rapid downhill clinical course even with optimal therapy. The clinical significance of these paraneoplastic manifestations is discussed.

Adult↗

PubMed1999

Case report: portal vein thrombosis associated with hereditary protein C deficiency: a report of two cases.

Protein C deficiency is one of the causes of curable or preventable portal vein thrombosis. We report two patients of portal vein thrombosis associated with hereditary protein C deficiency. The first patient presented with continuous right upper quadrant pain and high fever. The abdominal sonography revealed normal liver parenchyma but portal vein and superior mesenteric vein thrombosis. Based on a 55% (normal 70-140%) plasma protein C level, he was diagnosed as having protein C deficiency. A trace of his family history showed that his elder brother also had protein C deficiency with a 50% plasma C level. Both patients received anticoagulant therapy. The younger brother showed good response. Unfortunately, the elder one suffered from recurrent episodes of variceal bleeding and received a life-saving splenectomy and devascularization. We herein remind clinicians that early screening and therapy are helpful in preventing late complications of protein C deficiency with portal vein thrombosis.

Abdomen, Acute↗