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Biomedical subjects

K C Choi

Publications and source records attributed to K C Choi.

90 records · Page 5Linked to original sources
PubMed1993

Cimetidine improves the accuracy of creatinine clearance as an indicator for glomerular filtration rate.

BACKGROUND: Although endogenous creatinine clearance is often used as an indicator for the glomerular filtration rate (GFR), it may result in an overestimation due to its tubular secretion. Since cimetidine is known to inhibit tubular secretion of creatinine, it may improve the accuracy of the creatinine clearance in measuring GFR. METHODS: Creatinine clearance (Ccr) was compared with iothalamate clearance (C1oth) during oral administration of either placebo or cimetidine in 25 patients with varying degrees of renal dysfunction. RESULTS: Cimetidine itself had no effect on C1oth but decreased Ccr, improving its validity, as measured by a significant decrease of Ccr/C1oth from 1.72 during placebo to 1.17 during cimetidine administration. The degree of overestimation measured by the Ccr was more pronounced in those with more severe renal dysfunction. A significant inverse correlation was noted between Ccr/C1oth and GFR. No apparent side effect due to cimetidine was noted. CONCLUSIONS: These results suggest that cimetidine improves the accuracy of Ccr as an indicator for GFR in patients with varying degrees of renal dysfunction.

Adolescent↗
PubMed1992

Corrosive esophageal stricture: safety and effectiveness of balloon dilation.

The safety and long-term effectiveness of fluoroscopically guided balloon dilation for corrosive esophageal stricture was evaluated in 22 patients with a follow-up period of more than 1 year (range, 13-52 months). The average interval between corrosive agent ingestion and initial balloon dilation was 18 years (range, 2 months to 51 years). Balloons with a diameter of 5-8 mm were used in the initial attempt. The caliber of the balloon catheter was increased gradually over subsequent dilations, up to a diameter that allowed patients to swallow solid foods. Dilation of more than 17 mm in diameter was performed in five patients. Patients underwent one to five sessions. Esophageal rupture occurred in seven patients and was treated nonoperatively in five and surgically in two. With exclusion of these latter two, 11 of 20 could tolerate swallowing all kinds of food and nine could tolerate swallowing most foods. Balloon dilation in corrosive esophageal strictures is effective, but the high rupture rate indicates the need for extra caution.

Acetates↗
PubMed1992

Esophageal strictures: treatment with a new design of modified Gianturco stent. Work in progress.

To overcome the drawbacks of the modified Gianturco stent tube with barbs, a new barbless stent tube was constructed. Twenty-two barbless stent tubes 4.5-14.0 cm long were placed with a new introducing tube in 21 patients: 10 stent tubes in 10 patients with recurrent dysphagia after radiation therapy or chemotherapy, 10 in 10 patients with esophageal cancer in whom surgical management was contraindicated, and two in one patient with postoperative benign stricture. No technical failure or procedural complications occurred. After the procedure, all but two patients could ingest most or all foods. In two patients with an esophagorespiratory fistula and one patient with esophageal rupture, the barbless stent tube successfully occluded the fistula and rupture site. The stent tube migrated in one patient. Fifteen patients are surviving, with the stent tubes patent for 3-35 weeks (mean patency, 13 weeks); the six other patients died 7-24 weeks (mean, 16 weeks) after stent placement. It is concluded that barbless stent tubes show promise in the management of dysphagia caused by esophageal strictures.

Aged↗
PubMed1992

Percutaneous transhepatic biliary biopsy using gastrofiberscopic biopsy forceps.

To obtain a histopathologic diagnosis at the site of a biliary obstruction, we recently have performed 24 cases of biliary biopsy using gastrofiberscopic biopsy forceps (Olympus, Tokyo, Japan) via transhepatic tracts provided in the course of the procedure of percutaneous biliary drainage. Histopathologic diagnosis was successfully made at the first attempt of biopsy procedure but a second trial was made a week later in 6 cases who were negative for malignant cells on the first attempt. The histological results from the biopsy specimens were 18 adenocarcinomas, 5 chronic inflammations and one normal epithelium. Of 6 cases who were negative for malignant cells on forceps biopsy specimen, three cases were confirmed as adenocarcinoma of the ampulla of Vater, adenocarcinoma of the pancreas and chronic pancreatitis by surgical biopsy. The latter was a true negative result, which was diagnosed as chronic inflammation on forceps biopsy and verified as chronic pancreatitis by surgery. The remaining two cases were diagnosed as malignant obstructive jaundice by clinical and radiological follow-up findings. Major complications (bile peritonitis, bleeding, and hemopneumothorax) occurred in 3 patients, which mainly arose in the earlier period of study. This procedure can be performed at the same time as percutaneous transhepatic biliary drainage with low morbidity or mortality, and although the potential for perforation of bile ducts and injury to adjacent blood vessels is considered it is a useful addition to existing biopsy techniques for yielding material sufficient for histologic analysis.

Adult↗
PubMed1992

Comparison of 5-hydroxytryptamine1A-mediated hyperpolarization in CA1 and CA3 hippocampal pyramidal cells.

5-hydroxytryptamine (5-HT) hyperpolarizes hippocampal pyramidal cells in both areas CA1 and CA3 through an increase in potassium conductance. The receptor mediating the hyperpolarization in CA1 has been characterized as the 5-HT1A receptor, but has not been identified in area CA3. Intracellular recording techniques were used to record from CA1 and CA3 pyramidal cells in a hippocampal slice preparation. 5-HT agonists and antagonists were applied in known concentrations by bath perfusion. Antagonists were tested alone and for their ability to block the hyperpolarization elicited by 5-HT. The 5-HT1 agonist 5-carboxyamidotryptamine and 5-HT were full agonists and the 5-HT1A-selective ligand 8-hydroxydipropyl-aminotetralin hydrobromide was a partial agonist in both CA3 and CA1. The rank order potency was 5-carboxyamidotryptamine > 8-hydroxydipropyl-aminotetralin hydrobromide > 5-HT for both regions. The agonists were a half-log unit less potent and the maximum response elicited by 5-carboxyamidotryptamine and 5-HT was greater in area CA3 than in area CA1. The selective 5-HT1A antagonist BMY 7378 and the 5-HT1A/2 antagonist spiperone were competitive in area CA1, but insurmountable in area CA3. Other 5-HT antagonists that were not effective in blocking the 5-HT-mediated hyperpolarization included ketanserin, odansetron and BRL 24924. Based on these results, we conclude that the hyperpolarization elicited by 5-HT in areas CA1 and CA3 is mediated by the 5-HT1A receptor. However, there are significant differences in the nature of the 5-HT1A receptor-mediated hyperpolarization that may be attributed to differences in receptor-effector number, receptor-effector coupling and/or the structure of the recognition site.

Animals↗
PubMed1991

5-Hydroxytryptamine hyperpolarizes CA3 hippocampal pyramidal cells through an increase in potassium conductance.

The firing rate of hippocampal pyramidal cells recorded from the CA3 subfield is inhibited by 5-hydroxytryptamine (5-HT, serotonin) or by electrical stimulation of the ascending serotonergic fibers from the raphe. The mechanism of action of this inhibitory effect produced by 5-HT has not been determined. Intracellular recording techniques in the hippocampal slice preparation were used to measure the effect of 5-HT perfusion on membrane properties of CA3 pyramidal cells. In 15 out of 16 cells tested, 5-HT elicited a pronounced hyperpolarization concomitant with a decrease in membrane resistance. The hyperpolarization was not altered with either potassium chloride or potassium methylsulphate electrodes; the hyperpolarization by 5-HT was not present when electrodes were filled with cesium chloride. The reversal potential of the 5-HT mediated response was determined to be-105.5 mV in 3 mM KCl buffer using single electrode voltage clamp techniques. Based on these results we conclude that the mechanism of action of the 5-HT inhibition of CA3 hippocampal pyramidal cell excitability is due to an increase in potassium conductance.

Animals↗
PubMed1991

Desmoplakin I and II in acantholytic dermatoses: preservation in pemphigus vulgaris and pemphigus erythematosus and dissolution in Hailey-Hailey's disease and Darier's disease.

Desmoplakin I and II are important components of the attachment plaque of the desmosome which mediates cell to cell adhesion, in epithelial cells. In this study we used well-characterized antibody against desmoplakin I and II immunohistochemically and immunoelectron microscopically on two cases of pemphigus vulgaris and one case of pemphigus erythematosus and two cases each of Hailey-Hailey's disease and Darier's disease. In the normal human epidermis the desmosomes were demonstrated in a dotted pattern along cell periphery. In pemphigus vulgaris and pemphigus erythematosus acantholytic cells and the perilesional cells exhibited normal dotted pattern along the cell periphery. In Hailey-Hailey's disease and Darier's disease, the dotted pattern is lost in acantholysed and perilesional areas and anti-desmoplakin I + II positive proteins were observed diffusely in the cytoplasm. Immunoelectron microscopical findings correspond to these light microscopical observations. It is concluded that in autoimmune acantholytic disease such as pemphigus vulgaris and pemphigus erythematosus, desmoplakins are intact even in acantholytic cells, whereas in genodermatoses such as vulgaris and pemphigus erythematosus, desmoplakins are intact even in acantholytic cells, whereas in genodermatoses such as Hailey-Hailey's disease and Darier's disease primary or secondary abnormalities abnormalities of desmosomes may be involved in their pathogenesis.

Acantholysis↗
PubMed1991

Esophagogastric neoplasms: palliation with a modified gianturco stent.

Self-expanding metallic stents of a modified Gianturco design were used for palliative treatment of malignant esophagogastric strictures. Over a 10-month period, 10 stents were placed in nine patients. All patients with severe dysphagia due to malignant strictures in whom all other treatment options had failed were candidates for these stents. Neither extensive length of esophageal involvement nor complete esophageal obstruction was a contraindication. All stents were placed with fluoroscopic guidance without any technical failures or procedural morbidity or mortality. Mild reflux occurred in three patients in whom the stent tubes straddled the distal esophageal sphincter. Five patients were still alive after 1-8 months. The remaining four patients died 6-28 weeks after stent placement; all stents were patent at the time of death. These stents are easy to insert, safe, and reasonably effective for short-term palliative treatment of esophagogastric neoplasms.

Adenocarcinoma↗
PubMed1991

High salt intake attenuates the development of hypertension in two-kidney, one-clip Goldblatt rats.

Effects of high salt intake on the early onset of hypertension were examined in two-kidney, one-clip rats. They were divided into high salt and control groups which were supplied with 1.0% NaCl and tap water, respectively, as a drinking solution for 12 days after clipping the left renal artery. The high salt group showed a lower plasma renin concentration and a higher plasma atrial natriuretic peptide (ANP) along with an attenuation of the magnitude of early hypertension, as compared with the control group. A significant positive correlation between blood pressure and plasma renin concentration and an inverse correlation between plasma renin concentration and ANP were shown. Cortical renal renin content was comparable between the two groups. In another two groups of sham-clipped rats, the high salt group did not differ from the tap water-drinking group in any of the parameters examined, except that ANP was significantly higher. These results demonstrate that high salt intake attenuates the developmental phase of hypertension in two-kidney, one-clip rats by increasing the ANP and suppressing the release of renin.

Animals↗
PubMed1990

Immunohistochemical differentiation of basal cell epithelioma from cutaneous appendages using monoclonal anti-glycoprotein antibody TNKH1. Its application in Mohs' micrographic surgery.

TNKH1, which was primarily developed to detect differentiated melanocytic tumor cells, was found to recognize basal keratinocytes of hair follicle and some basal keratinocytes of human epidermis. Thus, TNKH1 decorated the basal cells of following structures: epidermis (39 of 54, only part of each specimen [OPES]), upper hair follicle (one of 24, OPES), lower hair follicle (21 of 21, very high rate of each specimen [VHES]), sebaceous duct (14 of 15, VHES), sebaceous gland (ten of 14, germinative cells near duct), eccrine duct (three of 19, OPES). Epithelial tumors, considered to be derived from or differentiating toward hair follicle such as trichilemmoma (one of one, VHES) and basal cell epithelioma (BCE) (32 of 32, VHES) were labeled not only in the peripheral cells but in their entirety. On the other hand, epidermal tumors, such as seborrheic keratosis (ten of 11, OPES), actinic keratosis (two of three, OPES), and squamous cell carcinoma (one of two, OPES), showed an irregular peripheral basal cell staining as in normal epidermis. The apocrine sweat apparatus and eccrine secretory portion were negative. Eccrine ductal tumors such as syringoma (two tested), eccrine acrospiroma (one), and eccrine carcinoma (two) were TNKH1 negative. Taking advantage of this total labeling of BCE versus peripheral labeling of the hair follicle, the authors could distinguish BCE tissue from other structures clearly. Among confusing structures the upper hair follicle and the eccrine duct were excluded easily because of their negative staining with TNKH1. The lower hair follicle was TNKH1 positive but only in the outer basal layer, whereas the BCE was TNKH1 positive in its entire basaloid cells. The result indicated that TNKH1 will be a useful antibody in Mohs' micrographic surgery.

Antibodies, Monoclonal↗
PubMed1990

Infantile digital fibromatosis. Immunohistochemical and immunoelectron microscopic studies.

A typical case of infantile digital fibromatosis (IDF) was studied with antibodies raised against actin, vimentin, desmin and several species of cytokeratin. Strong reactions were observed for desmin, cytokeratin and CK-5, and moderate reactions for vimentin and actin. The diagnostic intracytoplasmic inclusion bodies within the tumor cells were ultrastructurally composed of aggregations of dense microfilaments. Immunoelectron microscopy showed that these filament aggregations are positively stained with anti-actin antibody. From these results, we suggest that the large tumor cell of IDF is a myofibroblast and may originate from or differentiate toward vascular smooth muscle cells, because only this type of smooth muscle can coexpress desmin, vimentin and cytokeratin.

Actins↗
PubMed1990

Prevention of myelinolysis in rats by dexamethasone or colchicine.

The purpose of the present investigation was to determine whether dexamethasone, an agent known to preserve the blood-brain barrier, and colchicine, an agent that impairs mobilization of macrophages, can prevent demyelinating lesions associated with rapid correction of hyponatremia in the experimental animal. Hyponatremia was induced in rats with Pitressin and water. After 4 days hyponatremic rats received hypertonic saline alone or hypertonic saline plus dexamethasone or colchicine. All of the 9 rats that received only 5% NaCl developed demyelinating disease, while 3 of 6 rats treated with dexamethasone and 5 of 15 rats treated with colchicine showed no CNS abnormality. The results of our investigation might help understand the pathogenetic mechanism of central pontine myelinolysis in humans, a disease attributed to rapid correction of hyponatremia.

Animals↗
PubMed1989

Radiological evaluation of hepatic artery aneurysms.

The authors report 4 cases of hepatic artery aneurysm confirmed by computed tomography, sonography, angiography, and/or surgery. Three aneurysms involved the right hepatic artery and 1 involved the common hepatic artery. Two cases were treated with surgery, and the other 2 cases with transcatheter embolization. The clinical and radiological features of this entity are described together with a review of the pertinent literature.

Adult↗
PubMed1989

Danger of central pontine myelinolysis in hypotonic dehydration and recommendation for treatment.

Isotonic saline is the fluid most commonly used for treatment of asymptomatic hypotonic dehydration, but as shown in the case presented in this article, rapid increase in serum sodium may follow administration of isotonic saline, leading to the development of central pontine myelinolysis (CPM). Because the necessity of rapid correction is less, whereas the risk of CPM is greater with chronic asymptomatic hyponatremia than with acute hyponatremia, use of a half normal saline might be more appropriate than normal saline for treating certain patients with hypotonic dehydration with asymptomatic hyponatremia. The calculations indicate that half normal saline will expand the extracellular volume quite effectively, but the rate of increase in serum sodium will be considerably slower than that with normal saline.

Dehydration↗
PubMed1985

Thickening of the capillary basement membrane of the quadriceps muscle in Vacor-induced diabetic patients.

The effect of Vacor diabetes mellitus on the quadriceps muscle capillary basement membrane thickness has been examined by the electron microscopic method. With this procedure, it was possible to obtain an objective evaluation of the significance of capillary basement membrane thickening in Vacor diabetes mellitus. The results of such a study on the muscle capillary basement membrane in 10 normal subjects and 9 Vacor-poisoned patients have demonstrated the following: (1) the average basement membrane width of Vacor patients (2801 A +/- SD 614) is over twice that of normal subjects (1300 +/- 185 A), and all 9 cases demonstrated muscle capillary basement membrane thickening; (2) there is a significant association of basement membrane width with age (P less than 0.01), but not with the duration of the disease or fasting blood glucose values in the Vacor group. The results of the present study indicate that diabetes mellitus induced by Vacor poisoning can lead to microangiopathy, and that such basement membrane thickening is an early and consistent finding.

Adolescent↗