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Biomedical subjects

H R Chen

Publications and source records attributed to H R Chen.

At least 19 recordsLinked to original sources
PubMed1995

Mandibular arteriovenous malformation diagnosed by MR and MRA: a case report.

A case of mandibular arteriovenous malformation (AVM) is presented. Prompt diagnosis and appropriate management are essential due to massive bleeding or even death after dental extraction or biopsy. Angiography remains the gold standard in detecting the lesion. Magnetic resonance (MR) imaging with spin-echo sequences reveals the vascular malformation as signal-void. MR angiography can demonstrate the nidus, dilated artery and vein. MR imaging and MR angiography can supplement angiography in the diagnosis of mandibular AVM.

Arteriovenous Malformations↗
PubMed1994

Functional association of essential splicing factor(s) with PRP19 in a protein complex.

We have previously shown that the yeast PRP19 protein is a spliceosomal component, but is not tightly associated with small nuclear RNAs. It appears to associate with the spliceosome concomitant with or just after dissociation of the U4 small nuclear RNA during spliceosome assembly. We have found that PRP19 is associated with a protein complex in the splicing extract and that at least one of the associated components is essential for splicing. Taking advantage of the epitope tagging technique, we have isolated the PRP19-associated complex by affinity chromatography. The isolated complex is functional for complementation for the heat-inactivated prp19 mutant extract, and consists of at least seven polypeptides in addition to PRP19. At least three of these can interact directly with the PRP19 protein. We also show that the PRP19 protein itself is in an oligomeric form, which might be a prerequisite for its interaction with these proteins.

Base Sequence↗
PubMed1994

Percutaneous endoscopic polypectomy of gallbladder polyps.

We report here our preliminary experience with percutaneous endoscopic polypectomy of gallbladder polyps. Five patients with a total of 17 cholesterol polyps (size: 4-6 mm) and one patient with two gallbladder adenomas (size: 5 mm), four of whom were symptomatic and all of whom refused cholecystectomy, underwent a single-stage procedure under epidural anesthesia. All patients had functioning gallbladders, as assessed by oral cholecystography after stimulation. Following a small incision, the gallbladder was pulled out of the abdominal wall, incised, and a cholecystoscope introduced. The polyps were coagulated at their stalk using microwave irradiation (70-80 mA, 9 sec) and removed for histopathological evaluation thereafter. A catheter was left in situ for ten days. Follow-up for a mean of 11.6 months (8-16 months) showed all patients to be symptom-free and without recurrence of polyps on ultrasonography. Gallbladder function was assessed in five cases by meal-stimulated oral cholecystography, and in one by hepato-iminodiacetate acid (HIDA) scan and was found to be well preserved. The preliminary results warrant further evaluation of this method of removing indeterminate gallbladder polyps.

Adult↗
PubMed1993

Determination of glycyrrhizin and glycyrrhetinic acid in traditional Chinese medicinal preparations by capillary electrophoresis.

A simple, rapid, accurate and reproducible capillary electrophoretic method was developed for the assay of glycyrrhizin and glycyrrhetinic acid in traditional Chinese medicinal preparations. The buffer solution used in this method was acetonitrile and 0.02 M sodium dihydrogen-phosphate solution adjusted to pH 7.5 with 0.05 M sodium hydroxide. The linear calibration range was 0.04-2.00 mg/ml (r = 0.9988) for glycyrrhizin and 0.007-0.35 mg/ml (r = 0.9985) for glycyrrhetinic acid and recoveries were 98.1-101.3% for glycyrrhizin and 98.5-101.4% for glycyrrhetinic acid. The relative standard deviations were 1.02% (n = 6) for glycyrrhizin and 0.91% (n = 6) for glycyrrhetinic acid. The content of these two acids in Glycyrrhizae Radix and Glycyrrhizae Radix-containing Chinese medicinal preparations was successfully determined within 10 min.

Calibration↗
PubMed1992

[Prevention of pancreatic fistula in pancreaticoduodenectomy: cannulation of the pancreatic duct].

Fifty-two patients with malignant tumours underwent pancreaticoduodenectomy in the past 13 years. A plastic catheter, 3 mm in diameter and 40 cm in length, was used for pancreatic duct drainage and stent, with one end of it inserted into the pancreatic duct and the other end in the jejunal lumen. The cannulation was found to be very effective in stenting the stump pancreatic duct and draining the pancreatic juice away from the anastomotic stoma, hence preventing postoperative leakage. Temporary postoperative fistula occurred in only one patient, and operative death was noted.

Adult↗
PubMed1991

Hydrogen peroxide contrast hepatosonography.

Hydrogen peroxide contrast hepatosonography (HPCH), a new technique, was developed for liver examination. On examination, 5-10 ml of 2-3% hydrogen peroxide was injected into the rectum through a dual-channel rubber tube. When hydrogen peroxide passed through the mucosa into the portal vein, the fast flowing contrast echoes were seen, and the liver parenchyma was covered by enhanced echoes. A total of 297 subjects were examined by HPCH with a successful contrast rate of 95.6%. In normal subjects, dense contrast echoes were visible throughout the liver. But in patients with hepatoma, hemangioma, cyst and abscess, contrast echo defects were noted. We conclude that HPCE is of great value in the differentiation of space-occupying lesions and measurement of portal circulation time and blood flow velocity in spite of its untoward reactions.

Adolescent↗
PubMed1991

Cystic duct occlusion by microwave tissue coagulator in rabbits.

In this preliminary study a flexible bipolar microwave electrode, 1.8 mm in diameter, was designed to occlude the cystic duct in 18 rabbits. Thermal model tests were performed to evaluate the effect of the antenna and to master the coagulating condition. Through surgical cholecystostomy, the antenna was inserted into the proximal cystic duct for various coagulation treatments. Cholecystography showed that the cystic duct was occluded minutes to hours after coagulation. Histologically, the microwave technique induced a chronic inflammation and fibrosis which eventually obliterated the coagulated cystic duct permanently. In group A (30 mA for 20 s) the cystic duct epithelium regeneration occurred and surrounding liver damage was limited, while in groups B (50 mA for 10 s) and C (70 mA for 6 s) no epithelium regeneration was observed and injury to the liver was mild to moderate. It was found that microwaves generated at 50 mA for 10 s to occlude the rabbit's cystic duct are effective and less injurious.

Animals↗
PubMed1990

[Dark epithelial cells in oral premalignant lesions].

Dark basal epithelial cells (D cells) are characterized by a strong affinity for basic dyes and by the high electron density of the cytoplasm and nucleus. These cells have been considered to be putative dedifferentiated precursors of a neoplastic keratinocyte. They are significantly increased in preneoplastic lesions of the human airway and rat trachea induced with chemical carcinogens and/or tumor promoters. Twenty-four cases of oral premalignant lesions were classified as slight, moderate and severe dysplasia, and carcinoma in situ according to the histologic criteria proposed by MacDonald, katz and Pindborg. The percentage of appearance in D-cells of the dysplastic basal layer was calculated and shown as follows: in slight dysplasia 10.6 +/- 0.6%, in moderate dysplasia 22.9 +/- 0.8%, in severe dysplasia 23.9 +/- 0.4%, and in carcinoma in situ 31.4 +/- 0.9%. This result revealed that the increase in the number of D-cells in the basal epithelial layer was in proportion to the severity of the epithelial dysplasia. Thus, the D-cells probably can be used as an indicator in premalignant lesions of the oral cavity.

Epithelium↗