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Biomedical subjects

K C Choi

Publications and source records attributed to K C Choi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Esophagorespiratory fistulae due to esophageal carcinoma: palliation with a covered Gianturco stent.

PURPOSE: To evaluate therapeutic effects and complications of a covered Gianturco stent for esophagorespiratory fistulae. MATERIALS AND METHODS: Of 95 patients with esophageal carcinomas, 10 had esophagorespiratory fistulae and were treated with a silicone-covered Gianturco stent. The authors retrospectively assessed patients' food intake capacity and delayed problem of the stent. RESULTS: All fistulae were occluded without immediate complications. Two patients could swallow all foods; four, most foods; three soft foods; and one, only liquids. Clinical problems occurred between 1 and 24 weeks in four patients: reopened fistula (n = 1), recurrent fistula (n = 1) (both patients were successfully treated with another esophageal stent), and dyspnea (n = 2) due to tracheal compression by stent and tracheal invasion by tumor (one patient was treated with a tracheal stent). CONCLUSION: A silicone-covered modified Gianturco stent is effective for palliation of esophagorespiratory fistulae caused by esophageal cancer. Simultaneous use of a tracheal stent is recommended for extrinsic tracheal narrowing by the proximal tip of the stent and invasion by tumor.

Bronchial Fistula↗
PubMed1996

Tuberous sclerosis and polycystic kidney disease. A case report.

Polycystic kidney disease is a relatively uncommon finding of tuberous sclerosis. Furthermore, the renal insufficiency by the severe polycystic kidney disease is extremely rare in tuberous sclerosis. The patient was a 27-year-old man, complaining of generalized seizure and progressive abdominal distension. His clinical features were chracterized by epilepsy, mental retardation, skin abnormalities including adenoma sebaceum, shagreen patch and ash-leaf spots. Abdominal computed tomography demonstrated numerous variable sized cysts throughout both kidneys. Clinical and laboratory findings revealed chronic renal failure due to severe polycystic kidneys. On reviewing the literature, the present case is the first report of polycystic kidneys associated with tuberous sclerosis in Korea.

Adult↗
PubMed1995

Baclofen concentration-response curves differ between hippocampal subfields.

The hippocampus contains interneurons that release gamma-aminobutyric acid (GABA). GABA hyperpolarizes hippocampal CA1 and CA3 pyramidal cells through activation of GABAB postsynaptic receptors. GABAB and 5-hydroxytryptamine1A (5-HT1A) receptors share effector mechanism(s). Agonist potency and the maximal hyperpolarization produced by 5-HT1A receptor activation is different between the CA1 and CA3 subfields. We determined that baclofen, a selective GABAB agonist, was more potent and produced a greater maximal response in area CA3 than in CA1. The larger magnitude of the response can be attributed partly to the larger input resistance of CA3 neurons. GABAB receptor-effector coupling differences between area CA1 and CA3 are proposed as the mechanism underlying the baclofen response incongruities.

Animals↗
PubMed1995

A case of adult-onset Bartter's syndrome.

Bartter's Syndrome is characterized by renal potassium wasting with hypokalemia, metabolic alkalosis, increased renin-angiotensin-aldosterone system, normal blood pressure, resistance to the pressor effects of angiotensin II and juxtaglomerular cell hyperplasia. Most of the cases have been noted in the pediatric age group and adult-onset cases are very rare. We report a case of adult-onset Bartter's syndrome.

Adult↗
PubMed1995

Impairment of endothelium-dependent vasorelaxation in chronic two-kidney, one clip hypertensive rats.

The present study was to investigate a role for endothelium-derived nitric oxide (EDNO) system in the development and maintenance of 2-kidney, 1 clip (2K1C) hypertension. Effects of blocking the synthesis or supplementing the precursor of EDNO on the developmental phase of hypertension were examined in 2K1C rats. Responses of the isolated vasculature to phenylephrine, acetylcholine, sodium nitroprusside, and atrial natriuretic peptide were also examined in chronic 2K1C rats. Ingestion of NG-nitro-L-arginine methyl ester or L-arginine did not affect the development of hypertension in 2K1C rats. Contraction response to phenylephrine was enhanced and relaxation response to acetylcholine was attenuated in the thoracic aortic ring isolated from chronic hypertensive rats, both being more marked in the 12-week hypertensive than in the 7-week hypertensive. Indomethacin did not significantly affect the degree of the attenuated vasorelaxation response to acetylcholine. The vasorelaxation response to sodium nitroprusside and atrial natriuretic peptide remained unaltered in the hypertensives. These results indicate that EDNO does not affect the developmental phase of 2K1C hypertension, whereas an impaired endothelium-dependent vasorelaxation is associated with chronic 2K1C hypertension.

Acetylcholine↗
PubMed1994

Balloon dacryocystoplasty: results in the treatment of complete and partial obstructions of the nasolacrimal system.

PURPOSE: To evaluate the effectiveness of balloon dacryocystoplasty (DCP) in the treatment of complete and partial obstruction of the nasolacrimal system (NLS). MATERIALS AND METHODS: Fluoroscopically guided balloon DCP was attempted in 57 eyes of 50 consecutive patients with complete obstruction of the NLS and 24 eyes of 22 patients with partial obstruction of the NLS. With nasal endoscopic guidance, a 0.018-inch guide wire was introduced through the superior punctum into the inferior meatus of the nasal cavity and pulled out through the nare with a hemostat. A deflated angioplasty balloon catheter was introduced in a retrograde direction over the guide wire, and the balloon was dilated. RESULTS: Initial technical and clinical success was achieved in 29 of 57 eyes (51%) with complete obstruction and 17 of 24 eyes (71%) with partial obstruction. The 2-year cumulative clinical patency rates were 25% and 20% for partial and complete obstructions, respectively. The overall cumulative patency rate for all 81 eyes was 23%. CONCLUSION: Balloon DCP is simple and safe but has high failure and recurrence rates.

Adolescent↗
PubMed1994

Long- and short-term administration of corticosterone alters CA1 hippocampal neuronal properties.

The hippocampus contains a high concentration of the two corticosterone (CT) receptor subtypes, i.e. the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR). The endogenous steroid hormone CT has tenfold higher affinity for the MR than the GR. Under physiological conditions the MR is 80-95% occupied; during the daily diurnal surge of CT and following a stressful stimulus, the MR is 100% occupied and the GR 67-80% occupied. Previous studies have shown that CT can alter the synthesis of proteins within 30 min whereas it takes up to 7 days to alter the synthesis of other proteins. The physiological relevance of MR and GR activation is not totally understood. Intracellular recording techniques in hippocampal slices maintained in vitro were used to investigate chronic continuous or short-term effects of CT administration on hippocampal pyramidal cell activity. Rats were adrenalectomized (ADX) with or without CT replacement. The CT pellet used provided continuous plasma corticosterone levels equal to that seen in a normal rat in the morning. On the day of the experiment, slices from ADX animals were perfused with buffer containing no steroid, 1 nM CT or the selective GR agonist RU28362. Slices taken from ADX with CT pellet treated rats were superfused with buffer containing 1 nM CT or no steroid. Short-term and chronic CT treatment increased the membrane time constant, decreased the slow afterhyperpolarization (sAHP) amplitude, and increased the number of action potentials elicited by a depolarizing current pulse.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗
PubMed1994

Long-term effects of pentobarbital anesthesia on the atrial natriuretic peptide system in rats.

A long-term effect of pentobarbital treatment on the storage and release of atrial natriuretic peptide (ANP) was investigated in rats. The experimental group was treated with pentobarbital (50 mg/kg, ip), and the control group was injected with the vehicle only. They were used one week after the treatment. Male and female rats were used separately to see if there exists a sex difference in the response to pentobarbital. In male rats, the plasma ANP measured in a conscious state was significantly higher in the experimental group than in the control. The ANP content as well as the number of specific granules in the atrial tissue was significantly lower in the experimental group. In response to extracellular volume expansion (VE), amounting up to 5% of the body weight over 30 min, while the plasma ANP increased in the control, it did not significantly change in the experimental group. Urinary responses to the exogenous infusion of ANP did not differ in magnitude between the two groups. In female rats, neither the plasma level nor the atrial content of ANP (or the atrial granularity) was different between the experimental and control groups. Nor did the increase of plasma ANP in response to VE differ in magnitude between the two groups in female rats. These results indicate that pentobarbital may have a long-term effect on the storage and release of ANP.

Analysis of Variance↗
PubMed1994

Adult presentation of congenital cystic adenomatoid malformation of the lung: a case report.

Adult presentation of congenital cystic adenomatoid malformation(CCAM) of the lung is so rare that only 5 cases have been reported in the literature to date. We report the case of a 19-year-old female with CCAM in the left lower lobe. Computed tomography showed a multilobulated cystic lesion with multiple air-fluid levels and also showed focal enhancement of the solid component in the eccentrical portion of the lesion. Thoracic aortogram and selected bronchial arteriograms show a slightly enlarged and tortuous bronchial artery feeding the multilobulated cystic lesion. We present the clinical and radiological features of our case with a brief review of the literature.

Adult↗
PubMed1994

Attenuated release of atrial natriuretic peptide and vasorelaxation in streptozotocin-induced diabetic rats.

The present study was aimed at investigating the atrial natriuretic peptide (ANP) and urinary responses to acute perturbations in fluid balance and the vascular function in diabetes mellitus (DM). DM was induced in rats by treatment with streptozotocin (50 mg/kg, i.p.). Ten weeks later, the plasma ANP concentration measured in the conscious state was significantly higher in DM group (27.5 +/- 3.9 pg/mL) than in the control (15.4 +/- 2.6 pg/mL), while the atrial tissue contents of ANP were lower. In response to acute extracellular volume expansion (VE), amounting up to 5% of body weight over 45 min, under thiopental anesthesia (50 mg/kg, i.p.), the magnitude of increase in plasma ANP was lower in the DM group than in the control (56.8 +/- 25.2 vs. 189.1 +/- 53.6% increases over the basal). Urinary sodium excretion during VE was also lower in the DM group. Acetylcholine-induced relaxation of the isolated aortic rings was attenuated in the DM group, which was partially restored by L-arginine-supplementation (2 g/L in drinking water). These results suggest that body fluid homeostasis and vascular functions are unfavorably altered in DM.

Animals↗
PubMed1994

Impairement of endothelium-dependent relaxation in chronic two-kidney, one clip hypertensive rats.

OBJECTIVES: Hypertension is commonly associated with an endothelial dysfunction that may contribute to the rise in blood pressure. Little information has been available so far on the role of endothelium-derived nitric oxide(EDNO) in renin-dependent, 2-kidney, 1 clip(2KIC) hypertension. The present study was aimed to determine a role for EDNO in the development and maintenance of 2KIC hypertension. METHODS: The effects of blocking synthesis or supplementation with precursor of EDNO on the development of hypertension were determined in 2KIC rats. Vascular responses to acetylcholine, nitroprusside, atrial natriuretic peptide and nifedipine were examined in 7- and 12-week hypertensive 2KIC rats. RESULTS: NG-nitro-L-arginine-methyl ester caused a sustained increase of blood pressure in normal rats, while it was only partially associated with a more pronounced increase of blood pressure in the developmental phase of hypertension in 2KIC rats. In 7-week and 12-week hypertensive rats, phenylephrine-induced contraction of the isolated thoracic aortic rings was more sensitive compared with control. Their acetylcholine-induced relaxation was attenuated while the responses to nitroprusside or atrial natriuretic peptide were unaltered. Although their blood pressure did not differ between 7-week and 12-week hypertensive groups, the attenuation in the acetylcholine-induced relaxation was more prominent in the latter with a longer duration of hypertension. Indomethacin did not affect the attenuated relaxation to acetylcholine. The relaxation response to nifedipine was more pronounced in 2KIC rats. CONCLUSION: These results indicate that ENDO has little influence of the 2KIC hypertension, at least during its developmental phase, which is associated with an activated reninangiotensin system. The chronic stage of 2KIC hypertension, however, is associated with an endothelial dysfunction which may contribute to the enhanced vasoconstriction and sustained high blood pressure.

Acetylcholine↗
PubMed1993

Complete obstruction of the nasolacrimal system. Part I. Treatment with balloon dilation.

Fluoroscopically guided balloon dilation in treatment of complete obstruction of the nasolacrimal system was assessed in 39 eyes of 35 patients. All patients had severe epiphora. With nasal endoscopic guidance, a 0.018-inch guide wire was introduced through the superior punctum into the inferior meatus of the nasal cavity and was pulled out through the nasal aperture with a hemostat. A deflated angioplasty balloon catheter was passed retrograde over the guide wire through the inferior meatus until it straddled the stricture. Balloons were dilated with water-soluble contrast medium. No major complications occurred. At 7 days after balloon dilation, epiphora decreased in 22 of 39 eyes; 17 demonstrated complete resolution of severe epiphora, and five showed incomplete resolution. At 2 months, improvement had not been maintained in 10 of the 22 eyes. This technique for treatment of complete obstruction of the nasolacrimal system is simple and safe, but the high failure and recurrence rates in this study are not encouraging.

Adolescent↗
PubMed1993

Complete obstruction of the nasolacrimal system. Part II. Treatment with expandable metallic stents.

To evaluate the clinical usefulness of expandable metallic stents for maintenance of the dilated nasolacrimal sac and duct, double stents were implanted under fluoroscopic guidance in seven patients with severe epiphora after failed balloon dacryocystoplasty. Stents were constructed of 0.25-mm stainless steel wire in a cylindrical zigzag configuration of 10 bends. A single stent was 4 mm in diameter when fully expanded and 10 mm long. The stent was placed accurately in all but one patient, in whom a second stent was placed accurately after removal of the dislodged stent with a hemostat under endoscopic guidance. After stent placement, all patients demonstrated complete resolution of epiphora. During follow-up of 4-20 weeks, complete blockage of the stent occurred in one patient. This was treated with intrastent balloon dacryocystoplasty. No stents migrated. Although the long-term validity of this treatment has not been proved, expandable metallic stents seem to be of value in the treatment of complete obstruction of the lacrimal sac and nasolacrimal duct.

Adult↗
PubMed1993

Chronic caffeine ingestion exacerbates 2-kidney, 1-clip hypertension and ameliorates deoxycorticosterone acetate-salt hypertension in rats.

The present study was aimed to determine the effect of caffeine on the development of renal hypertension. Two-kidney, 1-clip (2K1C) hypertension and deoxycorticosterone acetate (DOCA, 200 mg/kg, subcutaneous implantation)-salt (0.9% NaCl drinking) hypertension were instituted in Sprague-Dawley rats. They were then grouped into two groups each: one was supplemented with caffeine (0.1%) in their drinking solution and the other was not. Systolic blood pressure was measured up to 24 days. Caffeine exacerbated the development of 2K1C hypertension in association with a higher plasma renin concentration (PRC). Caffeine ingestion, however, did not exacerbate but ameliorated DOCA-salt hypertension in which PRC was comparable between the caffeine-ingested and control groups. Concentrations of plasma atrial natriuretic peptide (pANP) were significantly different between the caffeine-ingested and control groups neither in 2K1C nor in DOCA-salt rats, suggesting that ANP was not responsible for the modified blood pressure. Acute caffeine infusion (350 micrograms/min, 30 min) in anesthetized normotensive rats caused increases in urinary excretion (volume and sodium) and in PRC without significantly affecting the blood pressure and pANP. These results suggest that caffeine specifically exacerbates 2K1C hypertension through increasing renin release whereas it ameliorates DOCA-salt hypertension possibly through increasing renal excretion.

Administration, Oral↗