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Biomedical subjects

Y S Kwak

Publications and source records attributed to Y S Kwak.

At least 19 recordsLinked to original sources
PubMed1999

Renal osteodystrophy in pre-dialysis patients: ethnic difference?

The purpose of the present study is to investigate whether an ethnic difference exists in the incidence of renal osteodystrophy between Asian and Western countries in end-stage renal disease (ESRD) patients. We evaluated bone histology in 58 pre-dialysis patients (28 male, 30 female; mean age: 47.7 years). All patients had bone biopsies with quantitative histomorphometry and serological parameters such as intact PTH, osteocalcin, total alkaline phosphatase, and basal and deferoxamine-stimulated serum aluminum levels. We observed that 91.4% of all evaluated patients showed renal osteodystrophy before the start of dialytic therapy. Mild osteitis fibrosa were observed in 21 patients (36.2%), severe osteitis fibrosa in 5 patients (8.6%), mixed lesions in 7 patients (12.1%), osteomalacia in 6 patients (10.3%), aplastic bone disease in 14 patients (24.1%), and normal bone in 5 patients (8.6%). Among the bone histomorphometric parameters, fibrosis area rate (%) showed the best correlation with intact PTH, and osteocalcin and osteoid area rate (%) with total alkaline phosphatase. Aluminum-related bone disease was not observed. Among patients with aplastic bone disease, only 14.3% showed aluminum deposition of any significance (5% < stainable bone surface aluminum < 25%). In the diabetic patients, aplastic bone disease was most common, but no case was related to aluminum intoxication. In conclusion, the distribution of renal osteodystrophy in our study was different from that of Western countries in pre-dialysis patients. Our patients tended to have more mild-form osteitis fibrosa and normal findings, and less severe-form osteitis fibrosa and aplastic bone disease. Aluminum-related bone disease was not observed.

Adult↗
PubMed1998

N-carbamoyl-L-glutamate plus L-arginine can protect ammonia intoxication in rats with reduced functional liver mass.

We previously reported the protective effect of N-carbamoyl-L-glutamate plus L-arginine in rats given a lethal dose (LD99.9) of ammonium acetate (Kim, S. et al., Proc. Natl. Acad. Sci. 69, 3530-3533, 1971; ref.1). The present study was undertaken to find out whether the same compounds could also be effective even after the functional mass of the liver was significantly reduced. Thus, the protective effect of these compounds in 70% partial hepatectomized rats following the injection of sublethal dose of ammonium acetate was assessed. The mixture could significantly decrease blood ammonia level compared with PBS-injected control group. In addition, abnormal behaviors observed in the control rats were significantly improved. The protective effect on the behavioral change seemed to be closely related with their effect on blood ammonia level, showing a strong correlation between the blood ammonia level and the behavioral score. The findings provide a rational basis for the clinical use of N-carbamoyl-L-glutamate plus L-arginine in the prevention and treatment of hyperammonemia encountered in liver diseases.

Acetates↗
PubMed1998

Toward clinical end-user computing: programmable order protocols for efficient human computer interaction.

We have developed and implemented an efficient method of managing routine patient care information as a programmable group order protocol. The purpose of protocol is to minimize a labor-intensive manual computer interaction by grouping clinically related routine orders as a single entity, thus to greatly speed up the time taken for manual entry such as keyboard stroke and/or mouse clicking. User programmability is added to facilitate insertion, deletion and update of order items to be a locally independent operation. A sequence of menu screen is also programmable when a change of standard operation is needed. Department specific order protocols are classified into four categories to improve user convenience. The degree of efficiency is measured by a number of key strokes and entry time. In most cases the time to enter order protocol with correction is found to take less than one minute with less than five key strokes. The method of order protocol entry clearly demonstrates end-user computing capability so that department specific requirements are resolved without resorting to computer department personnel. Flexibility of managing individual physician specific protocols is also beneficial enough to enhance the morale toward a hospital information system currently in use.

Computer Graphics↗
PubMed1998

Study of user preference of graphic user interface in laboratory information system.

In order to elucidate employees satisfaction levels in using graphic user interface. (GUI) in a laboratory information system (LIS), users attitudes toward GUI versus CUI. (Character User Interface) in a similar LIS were surveyed one month after implementing upgraded version of LIS in a tertiary care university hospital laboratory. The outcome of the study showed that approximately two third of users preferred to have GUI in LIS. There was no difference in preference of GUI of users whether they had previous experience with GUI or not. However the female and older employees tend to shy away from GUI. The employee productivity was improved with GUI although it takes slightly longer program loading time than that of CUI. In conclusion, the laboratory employee satisfaction was higher with GUI than CUI and their productivity was improved with GUI.

Adult↗
PubMed1996

Hyperprolactinaemia and verapamil: prevalence and potential association with hypogonadism in men.

OBJECTIVE: Verapamil has been associated with hyperprolactinaemia, but there have been no population-based studies. Our objective was to determine the prevalence and degree of hyperprolactinaemia associated with verapamil in the clinical setting. DESIGN: Observation with cross-sectional and longitudinal components in the setting of an urban teaching hospital and its satellite out-patient clinics. PATIENTS: Male out-patients excluding those taking other drugs known to raise PRL, renal failure and known primary hypothyroidism (1265 eligible subjects). Control subjects were drawn from eligible out-patients not taking verapamil. MEASUREMENTS: Serum PRL levels, frequency of persistent hyperprolactinaemia and total testosterone levels. RESULTS: Prolactin levels were obtained in 449 subjects on verapamil (35.5% response rate) and 166 controls. The proportions of individuals with hyperprolactinaemia (PRL > 460 mU/l) were 0.085 and 0.030 in the verapamil and control groups, respectively (P = 0.012, X2-test). The mean (+/- SD) serum PRL levels were 267 +/- 205 and 203 +/- 118 mU/l in the verapamil and control groups, respectively (P < 0.001, independent t-test). Of the 38 patients with previously determined elevated PRL levels, follow-up data were obtained in 25 (65.8%); one was found to have a pituitary adenoma and was excluded from the analysis. Fifteen of the 24 were still on verapamil (Group 1) and 14 (93.3%) continued to be hyperprolactinaemic. In 9 patients verapamil had been discontinued (Group 2) and all had normal PRL levels. Continued verapamil use was associated with persistent hyperprolactinaemia (odds ratio > 120, P < 0.00001). The mean +/- SD serum testosterone levels at follow-up were significantly lower in Group 1 (6.16 +/- 2.52 nmol/l) than in Group 2 (9.42 +/- 3.92 nmol/l, P = 0.029, independent t-test). CONCLUSIONS: The prevalence of hyperprolactinaemia associated with verapamil use in this study of male out-patients was 8.5% (95% CI 5.9-11.1%). The persistence of hyperprolactinaemia when verapamil was continued (Group 1) and the return to normal PRL levels when verapamil was discontinued (Group 2) confirm verapamil's causal role in the development of hyperprolactinaemia. While low testosterone levels were common in both groups, testosterone levels were lower in patients on verapamil. Our data suggest that screening for hyperprolactinaemia should be considered in male patients taking verapamil.

Aged↗
PubMed1995

A hyperthermophilic sulfur-reducing archaebacterium, Thermococcus sp. DT1331, isolated from a deep-sea hydrothermal vent.

A hyperthermophilic archaebacterium was isolated from a deep-sea black smoker chimney (depth, 760 m) at the Minami-ensei Knoll (28 degrees 23'N, 127 degrees 38'E). The strain, designated DT1331, was a coccoid shaped bacterium about 0.5 to 1.0 microns in diameter. The cells were surrounded by a cell envelope. The temperature for growth was between 55 degrees C and 93 degrees C with an optimum 80 degrees C. The growth occurred from pH 4.5 to 8.5 and the optimum pH was 6.0. DT1331 required 1% to 5% NaCl for growth and cell lysis was observed below 1% NaCl concentration. The strain was an anaerobic chemoorganotroph requiring elemental sulfur obligately. Organic substrates used included tryptone, peptone, soytone, casein, gelatin, and yeast extract. Under the optimal conditions, DT1331 had a generation time of 50 min and could reach densities of about 1.5 x 10(8) cells/ml. DT1331 was resistant to ampicillin, chloramphenicol, erythromycin, kanamycin, streptomycin, and tetracycline, which was one of the common characteristics of archaebacteria. The G+C content of DT1331 was 52.3 mol%. Analysis of the 16S rRNA gene by restriction enzymes coincided with those of Thermococcus celer, indicating that this strain belonged to the genus Thermococcus.

Anti-Bacterial Agents↗
PubMed1993

Accuracy of the One Touch II whole blood glucose analyzer when used by analysts with diverse technical backgrounds.

BACKGROUND: The accuracy of hand-held analytical systems is dependent on the complexity of the instrument and the technical skills of the tester. We evaluated the analytical performance of the LifeScan One Touch II glucose analyzer when used by persons with various levels of technical skill and experience. METHODS: A medical technologist conducted tests on three One Touch II systems to ensure that the units were functioning properly. The technologist then trained six analysts (a physician, a registered nurse, a licensed practical nurse, a physician assistant, and two patients) in the proper use of the glucose analyzer. RESULTS: In the hands of a medical technologist, the precision of the three glucose analyzers tested was from 1.0% to 1.9% coefficient of variation (CV) and from 2.3% to 4.2% CV for the low- and high-quality control materials, respectively. The day-to-day precision (5-day period) was from 2.1% to 3.6% CV, and from 3.5% to 4.1% CV for the low- and high-quality control materials, respectively. Comparisons of the glucose values (n = 40 fresh patient serum samples) with a reference method yielded a correlation coefficient of 0.992 to 0.993, and an overall bias of -7%. Although the values obtained by the six operators were statistically different, the differences were not clinically relevant. CONCLUSIONS: Our data suggest that the One Touch II glucose analyzer is a reliable system, and that its function is not dependent on the technical skills of the operator.

Blood Glucose↗
PubMed1993

Matrix effects on proficiency testing materials. Impact on accuracy of cholesterol measurement in laboratories in the nation's largest hospital system.

The objective of this collaborative study with the Department of Veterans Affairs (VA), College of American Pathologists (CAP), and the Centers for Disease Control and Prevention (CDC) was to quantitate the matrix-induced biases of cholesterol measurements on the CAP Comprehensive Chemistry Surveys materials used in proficiency testing (PT). A total of 174 VA Medical Centers outpatient clinics and clinical laboratories participate in the VA-CDC National Cholesterol Standardization and Certification Program. This study was conducted in 112 VA laboratories that have been standardized for measuring cholesterol accurately (within +/- 3.0% of the CDC reference-method values) using fresh, unfrozen, unadulterated human serum samples. Fresh serum samples and 1990 CAP Surveys materials were sent by overnight mail, and the laboratories were asked to analyze them simultaneously in triplicate in a single analytic batch run. The results showed significant matrix-effect biases with the CAP Surveys materials with six of the eight major peer groups, despite the fact that accuracy of cholesterol measurements was maintained with fresh serum samples. The magnitude and direction (positive or negative) of the matrix-effect biases were instrument, reagent, and method specific using the following peer groups: du Pont Dimension (-8.9%); Beckman CX4, CX5, and CX7 (-5.5%); Kodak Ektachem 400, 500, and 700 (+4.4%); Instrumentation Laboratory Monarch (-3.1%); Baxter Paramax (-2.4%); Technicon SMAC and RA (+1.3%); Hitachi/BMD 704 through 747 (+0.4%); and Abbott Spectrum (-0.3%). The CAP PT materials used currently do not behave in a manner identical to fresh human serum when measuring cholesterol on many, but not all, analytic systems. The observed biases due to "matrix effects" with PT materials will cause incorrect conclusions about the accuracy of many laboratory procedures performed on fresh patient specimens. This matrix-effect phenomenon will severely hamper interlaboratory accuracy transfer, standardization efforts, and monitoring performance of a laboratory's testing accuracy with the use of the current survey materials used in PT programs. Collaborative efforts are needed to (1) improve PT fluids to analytically behave more like fresh, human serum; (2) improve instrument design and reagent formulation; and (3) select methods and methodologic parameters that are more "robust" and less sensitive to the exact character of processed calibrators, quality control, and PT materials.

Bias↗
PubMed1992

Accurate measurement of serum total cholesterol: the need for standardization.

Heightened awareness of the importance of cholesterol and heart disease has increased cholesterol testing in the United States. The demand for reliable cholesterol measurements has become a focal concern of the patient as well as the clinician. This paper covers the major analytical and preanalytical issues and factors that can affect the reliability of cholesterol results. We discuss factors that lead to impression and inaccuracy; solutions for some of the major problems; resources and techniques to help standardize cholesterol measurement; and preanalytical issues that can affect cholesterol results--i.e., patient preparation; collection, processing, storage and proper analysis of the specimen; biological and seasonal variations; age and gender; diet; alcohol consumption; weight changes; exercise; primary diseases; and infections and trauma. Many of these can be controlled by the physician, resulting in more reliable cholesterol readings under stable metabolic conditions. Accurate values will help to classify the patient's coronary heart disease risk, define appropriate treatment strategies, and simplify monitoring of dietary and/or drug intervention.

Blood Chemical Analysis↗
PubMed1991

Effect of glycine on retroperitoneal and intraperitoneal organs in the rat model.

Twenty Sprague Dawley rats were administered various doses of 1.5% amino acetic acid (glycine), lactated Ringer's, and water, both intravenously and retroperitoneally, in an attempt to recreate the post-transurethral resection syndrome in a rat model. The kidneys, liver, and pancreas were harvested 6 hours after exposure and examined pathologically. Water and lactated Ringer's had no histologic effect on these organs. Glycine was found to have a toxic effect on the kidneys and liver and this effect was dose related. Based on these results, it is postulated that glycine toxicity may play a significant role as a causative factor in producing the post-transurethral resection syndrome.

Animals↗
PubMed1990

Psychiatric epidemiology in Korea. Part I: Gender and age differences in Seoul.

The most dramatic finding was the very high prevalence of alcohol abuse, using DSM-III criteria, among men in Seoul, Korea. The prevalence of other psychiatric disorders was lower than in St. Louis, Missouri. With the current biological emphasis in psychiatry, questions may be raised regarding the different prevalence rates of schizophrenia, affective disorders, and even alcoholism. The deficit of the aldehyde dehydrogenase isoenzyme 1 has been hypothesized to reduce the prevalence of alcohol abuse among Asians. Twenty-five percent of Koreans have been found to be deficient in the enzyme, but despite this their prevalence of alcohol abuse is higher than among Americans. Cultural issues are paramount in the much lower prevalence of alcohol abuse among women in Korea.

Adolescent↗
PubMed1990

Psychiatric epidemiology in Korea. Part II: Urban and rural differences.

This paper compares the findings in rural Korea and in the urban capital city of Seoul, Korea. In rural Korea 1966 subjects and in Seoul 3134 subjects were interviewed with the National Institute of Mental Health Diagnostic Interview Schedule. We found that the prevalence of psychiatric disorders, including alcohol dependence, was higher in rural Korea than in the urban setting. Comparing men and women, the prevalence of psychiatric disorders was higher in women. The exception was alcohol abuse/dependence, which was much higher among men, as was antisocial personality disorder. Comparison of prevalence by age groups showed that, in contrast to American studies, there was a tendency for prevalence to increase with increasing age. Alcohol abuse/dependence was much higher in rural Korea compared with St. Louis. Drug abuse/dependence was much higher in St. Louis. Other interesting similarities and differences are discussed.

Adolescent↗
PubMed1987

The nationwide epidemiological study of mental disorders in korea.

The lifetime prevalences of DSM-III mental disorders using Korean version of DIS-III are presented. They were studied in 5,100 adults (aged 18 to 65) in household selected by two stage cluster sampling. Comparisons were made between regions, sex and age groups. International comparison with Epidemiologic Catchment Area program was also made.

Adolescent↗
PubMed1976

Study of drugs affecting cholesterol-induced atherosclerosis in rabbits.

1. Effects of various drugs on cholesterol-induced atherosclerosis in rabbits during the progression phase have been studied. The drugs tested are antimetabolites (mercaptopurine, hydroxyurea), surface active agents (sodiumdodecyl sulfate), inhibitor of adrenocoritcal steroid synthesis (o, p'-DDD), lysosome stablizers (chloroquine, acetylsalicylic acid) with antihistaminic (chlorpheniramine) and cholesterol binder (nystatin). 2. Mercaptopurine treatment showed marekd reduction in both atherosclerotic lesions and cholesterol concentrations of the serum and aorta. 3. Hydroxyurea reduced both the aortic cholesterol concentration and the lesions, but the serum cholesterol concentration remained high. 4. Sodiumdodecyl sulfate and o, o'-DDD showed slight inhibition of the development of atherosclerosis. 5. Pyridinocarbamate showed a slight beneficial effect on the prevention of atherosclerosis only when it was administered prior to the meal. 6. Nystatin, chloroquine and acetylsalicylic acid + chlorpheniramine showed little effect.

Animals↗
PubMedDate not supplied

Superficial spreading adenocarcinoma of appendix, cecum, and terminal ileum.

A case of superficial spreading adenocarcinoma involving terminal ileum, appendix and cecum is presented. The tumor might primarily arise from the proximal part of the appendix with extension to the cecum and terminal ileum, although multicentric origin of the tumor cannot be excluded. The mechanism underlying superficial infiltration of the tumor is through close contact and intramucosal lymphatic spread.

Adenocarcinoma↗