Biomedical subjects
Publications and source records attributed to T Chang.
A 68-year-old woman with metastatic breast carcinoma manifested bilateral tamoxifen-induced retinopathy after 9 years of low-dose therapy. Treatment with the drug was stopped, with partial resolution of the retinopathy and improvement in visual acuity over 2 1/2 years of follow-up.
Pirmenol enantiomers in dog plasma were quantified using a stereospecific high-performance liquid chromatographic method with ultraviolet detection at 262 nm. Racemic pirmenol and internal standard, (+)-propranolol, were isolated from dog plasma by a three-step extraction procedure using toluene, 0.1 M hydrochloric acid and hexane, respectively. A chiral analytical column (Chiralcel OJ) was used with a mobile phase consisting of hexane-isopropanol-diethylamine (98.9:1.0:0.1). Linear calibration curves were obtained in the concentration range 0.0200-5.00 micrograms/ml for each enantiomer. Precision of the method, expressed as coefficient of variation for nine quality control samples, was 7.1% for (+)-pirmenol and 6.4% for (-)-pirmenol. Bias was +/- 2.2% for (+)-pirmenol and +/- 1.5% for (-)-pirmenol in quality control samples.
The carp gamma-crystallin gene family was found to be composed of at least three members: gamma m1, gamma m2 and gamma m3. The encoded products are very similar to other known gamma-crystallins but with their own peculiarities: (1) they all have a high methionine content: 12.4%, 14% and 8.4% in gamma m1, gamma m2 and gamma m3, respectively; and (2) the amino acid sequences are aberrant in the region before connecting peptides and its corresponding region in motif 4. Their protein structures might remain the same as those of other gamma-crystallins since they retain all the conserved amino acid residues essential for maintaining the loops in the protein structures.
Explore the source record for details and available documents.
We report a case of vertebral arteriovenous fistula in which embolization was complicated by migration of two coils and a partially inflated balloon. In order to relieve compression to the spinal cord, the displaced balloon was punctured percutaneously. For both relieving compression to the spinal cord and obliterating the residual fistula, the dislodged coils in the partially thrombosed epidural venous sinus were removed percutaneously and placed in the fistula, and more coils were implanted in the fistula percutaneously through the needle. CT follow-up half a year later showed complete resolution of compression of the spinal cord and complete recovery from myelopathy was clinically apparent.
The clinical and ultrasonographic (US) features of 15 cases of mesenteric or omental cyst are herein described. This series included seven male and eight female patients, whose age ranged from 2-89 years. Correct clinical diagnosis was made in two children only, but preoperative US examination accurately demonstrated the lesion in 11 of 13 patients (85%). These cystic lesions usually had a thin wall, internal septations, and fluid content with sedimentation. Enteric duplication cysts had a relatively thick wall merging with the muscle layer of bowel loop, and multiloculation was noted mainly with cystic lymphangiomas or pseudocysts. The diagnostic and surgical management of these lesions are briefly reviewed and their US appearance is illustrated.
Hepatic microabscesses have been described in immunosuppressed patients. However, there has been no previous report concerning hepatic microabscesses caused by Escherichia coli (E. coli). Recently, we experienced a 75-year-old male patient who had suffered from fever and upper abdominal pain for 4 days. His laboratory tests revealed an increased erythrocyte sedimentation rate (55 mm/hr), the white cell count was 7500/cumm with 82% segmented leukocytes, minimally elevated serum alkaline phosphatase and serum glutamic-pyruvic transaminase. Ultrasonography (US) showed multiple tiny hypo- or nearly anechoic lesions (3-8mm) diffusely scattered in both hepatic lobes. Some lesions were too small to be demonstrated and only distal acoustic enhancement posterior to the lesions could be noted. Contrast-enhanced computed tomography (CT) scan subsequently demonstrated the tiny hypodense and cystic lesions and confirmed the US diagnosis of microabscesses. Cultures of blood and liver aspirates showed E. coli. Although US and CT appearance of hepatic microabscesses caused by E. coli may be characteristic, it is not specific. Differential diagnosis should include multiple biliary hamartomas, and definite diagnosis should be made by needle aspiration.
Ureteral stents have been widely used by urologists and interventional radiologists in the management of ureteral strictures, leaks or fistulas and in conjunction with extracorporeal shock wave lithotripsy of large renal calculi. In the long-term use, migrations, encrustations, or even stones formation may occur which make the stents malfunction. When cystoscopical or surgical removal of the malfunctioning stents is not successfully done, percutaneous retrieval can be the choice of treatment. We present two cases of percutaneous retrieval of the malfunctioning ureteral stent.
The distribution of Lipiodol in the liver and lungs following arterial or portal injection was studied in normal (n = 55) and cirrhotic rats (n = 20). Using magnified xeroradiography and radioisotope labeled tracers, it was found that Lipiodol was deposited mainly in the liver and lung after either arterial or portal administration. In control rats after arterial injection, deposits in the lung peaked after 2 hours and gradually declined over 48 hours; whereas after portal injection, the deposit steadily increased for 48 hours. Twenty-five percent of cirrhotic rats demonstrated a Lipiodol-induced military pattern in the lung. An increased number of portosystemic shunts in cirrhotic rats was also noted. These results suggest that cirrhosis of the liver may be a potential risk factor for developing pulmonary complications after Lipiodol administration.
We report a case of posterior fossa arteriovenous fistula with a possible arterial aneurysm. The patient was a 15-year-old female. She was transferred to us because of a sudden onset of dyspnea, severe headaches, and loss of consciousness. The CT scan found an abnormal vascular lesion in the posterior fossa. Calcification was noted in the wall of the largest abnormal vascular structure. The angiogram showed a focal aneurysmal dilatation of the hemispheric branch of the right posterior inferior cerebellar artery, followed by an arteriovenous fistula, which drained to the right transverse sinus. Embolization was performed by implanting a detachable balloon into the proximal end of the aneurysm. These abnormal vascular structures disappeared completely on the angiogram after the embolization. CT scan one week after embolization showed increased density in these abnormal vascular structures, with no enhancement after contrast, indicating thrombosis or the formation of a blood clot in their lumen. The CT half a year after embolization showed reduction in size and a low density change in the largest vascular structure with calcification in the wall. All other abnormal vascular structures disappeared. An angiogram half a year after the embolization confirmed no recurrence of the aneurysm or arteriovenous fistula.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
For the understanding of the CT findings of polymorphic reticulosis involving the upper respiratory tract, we reviewed eleven cases of this disease with initial CT study before treatment. CT revealed masses or swelling in the nose or nasal chamber, often with involvement of paranasal sinuses and medial parts of the orbit. In some, nonspecific minimal bony change (either bone destruction or bone sclerosis) was found. These CT findings are not specific. Any large mass in the nose and nasal fossa with little associated bone destruction should, however, raise the differential diagnosis of polymorphic reticulosis.
As part of the Canadian Wildlife Service monitoring of great blue herons in British Columbia, eggs were collected from three colonies with low, intermediate, and high levels of PCDD and PCDF contamination: Nicomekl, Vancouver, and Crofton, respectively. One egg from each nest was used for chemical analysis by GC-MS; the others were hatched. Liver microsomes were prepared from the heron chicks and used for determination of cytochrome P-450-dependent activities. No erythromycin N-demethylase activity was found in any sample. Ethoxyresorufin O-dealkylase activity in the Nicomekl group was similar to that in pigeons, a control altricial species. The ethoxyresorufin activity in the herons from the Crofton colony was 2.6-fold higher than in the Nicomekl group. The Vancouver colony was intermediate. No difference among the three heron colonies was found in pentoxyresorufin O-dealkylase activity, although levels were 20-33 times that in the pigeon. Chemical analysis was carried out on paired heron eggs. Vancouver and Crofton eggs contained 13.5 and 21 times the levels of 2,3,7,8-TCDD compared to the Nicomekl group. The Crofton eggs contained higher levels of several other contaminants also. A highly significant correlation (p less than .001) was found between ethoxyresorufin O-dealkylase and 2,3,7,8-TCDD concentrations. The correlation coefficient did not change when ethoxyresorufin O-dealkylase was compared to total chemical contamination using several toxic equivalency factors. Multiple regression analysis resulted in only one predictor variable for ethoxyresorufin O-dealkylase: 2,3,7,8-TCDD.
To study the regulation of the multiple forms of erythromycin N-demethylase, we determined the influence of sex and inducer treatment on this mixed-function oxidase activity in adult Wistar rats injected intraperitoneally once daily for 4 days with dexamethasone, pregnenolone-16 alpha-carbonitrile, phenobarbital, or 2% Tween 80 (control). Based on the results from a computer curve-fitting procedure (ENZFITTER) as well as Eadie-Hofstee and Lineweaver-Burk plots, at least two forms of erythromycin N-demethylase were present in control, dexamethasone, pregnenolone-16 alpha-carbonitrile, and phenobarbital-treated male rats and in control and dexamethasone-treated female rats. Only a high-affinity form was apparent in pregnenolone-16 alpha-carbonitrile and phenobarbital-treated female rats. Therefore, more than one form of erythromycin N-demethylase exists in hepatic microsomes from adult rats, depending on sex and inducer treatment. As well, at a substrate concentration commonly used in the erythromycin N-demethylase assay, the relative contribution of the high- and low-affinity forms to the enzyme activity varies with sex and inducer treatment.
Explore the source record for details and available documents.