Biomedical subjects

W K Lee

Publications and source records attributed to W K Lee.

At least 19 recordsLinked to original sources

PubMed1992

Extraction of penicillin G from simulated media by an emulsion liquid membrane process.

The extraction of penicillin G from simulated media was performed by water/oil/water (w/o/w) emulsion liquid membranes (ELMs) and studied under various operational conditions in a batch system. The degree of extraction achieved was between 80% and 95% under specific conditions. A concentration of greater than nine times the initial concentration of penicillin G in the external phase was obtained in the internal phase. The pH of the internal aqueous solution, containing a basic salt, was theoretically calculated on the basis of the amount of penicillin G transported into the internal phase. The calculated results agreed with the experimental data well and were used to select a suitable type and concentration of a basic salt in the internal phase to give a pH within the range 5 to 8 where penicillin G was stable after the termination of extraction. The extraction of penicillin G was successfully performed by the ELM process with sodium carbonate in the internal phase.

Biotechnology↗

PubMed1992

Longitudinal stress fracture of the tibia: two cases.

Stress fracture of the tibia occurs in individuals who subject their extremities to repeated trauma. They can arise in otherwise healthy bone that is subjected to excessive loads (as in the marathon runner) or in abnormal bone that is subjected to minor loads (as in osteoporosis). These fractures may be anywhere along the tibial shaft and tend to be either transverse or oblique in orientation. We report two cases of stress fracture that ran longitudinally in the distal one third of the tibia. Both patients were healthy and did not describe excessive physical activity prior to fracture. Both describe a repetitive twisting action prior to fracture. Computed tomography was diagnostic in both cases following abnormal bone scans and normal plain radiographs. This unusual pattern of fracture has been reported on only four occasions in five patients in the literature.

Adult↗

PubMed1992

Comparison of outcome among double, bifoil and Inoue balloon techniques for percutaneous mitral valvuloplasty in mitral stenosis.

The efficacy and complications of three different methods of percutaneous mitral valvuloplasty (PMV) were evaluated in 245 patients with mitral stenosis (MS). Eight six patients (35%) had severe MS defined in the mitral valve area (MVA) less than 1.0 cm2 (0.8 +/- 0.2) and Echoscore greater than or equal to 8(8.9 +/- 1.1). The results including post MCA greater than or equal to 1.5cm2 and complications, i.e, increment of mitral regurgitation (MR) greater than or equal to +1 and atrial septal defect (ASD) with Qp/Qs greater than or equal to 1.5 were compared in overall and in severe MS groups. There was no statistically significant difference in size of MVA before and after PMV between overall patients group and severe mitral stenosis group (0.8 +/- 0.1 vs 1.7 +/- 0.4cm2 in the double technique, 0.8 +/- 0.2 vs 1.5 +/- 0.3cm2 in the Bifoil technique and 0.7 +/- 0.2 vs 1.8 +/- 0.3cm2 in the Inoue technique. p: NS). However, a significantly larger number of patients in the severe MS group had better MVA with the double than the Bifoil technique [MVA greater than or equal to 1.5cm2; 42 (72%) vs 6 (46%), p less than 0.005] whereas higher complications were observed with the Bifoil than the Inoue technique (MR greater than or equal to +1; 9 (69%) vs 4 (27%), ASD (Qp/Qs greater than or equal to 1.5' 6 (46%) vs 2 (13%) p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Advanced glycosylation end products in the mesenteric artery.

We measured advanced glycosylation end products in the mesenteric artery of 37 patients (ages 29-82 years), 34 of whom were nondiabetic. Samples of arterial tissue were obtained during bowel resectioning. Advanced glycosylation end products were measured as collagen-linked fluorescence (excitation wavelength 370 nm, emission wavelength 440 nm) after collagenase digestion of tissue samples. Mean fluorescence of the arterial samples was 15 U/mg (range 5.3-27). Collagen fluorescence correlated with patients' age (r = 0.57; P less than 0.001). No difference in the collagen-linked fluorescence was observed between men and women (P = 0.63), hypertensive and normotensive patients (P = 0.44), smokers and nonsmokers (P = -0.52), and patients with and without symptomatic coronary heart disease (P = 0.7). This study demonstrates, for the first time, the relationship between collagen-linked fluorescence and patients' age in human arterial tissue ex vivo.

Adult↗

PubMed1991

Usefulness of OPC-8212, a quinolinone derivative, for chronic congestive heart failure in patients with ischemic heart disease or idiopathic dilated cardiomyopathy.

To evaluate the safety and efficacy of the inotropic agent OPC-8212 in patients with chronic congestive heart failure, 76 patients with impaired cardiac function and diminished exercise tolerance were studied. They were randomized to 12 weeks of double-blind therapy with either 60 mg/day of OPC-8212 or placebo. The study drug was added to their baseline medical regimen. The primary study outcome was the combined outcome of the time to either mortality (of all cause) or substantial worsening of heart failure (major morbidity), whichever occurred first. Treatment with OPC-8212 significantly (p less than 0.01) decreased the combination of major morbidity/mortality over 12 weeks of therapy. Quality of life, assessed by the Sickness Impact Profile questionnaire, was significantly improved in patients receiving OPC-8212 (p less than 0.01). Furthermore, ventricular premature contractions as assessed by 24-hour Holter monitoring were not increased with OPC-8212 treatment. Although patients treated with OPC-8212 were able to reach a significantly higher peak oxygen uptake and exercise longer during symptom-limited exercise, when data were analyzed as percent change from baseline, the absolute increases were small. These results suggest that OPC-8212 is beneficial in treating patients with congestive heart failure and that further evaluation of this new inotropic agent is warranted.

Adolescent↗

PubMed1991

Involvement of protein kinase C in the regulation of oocyte maturation in amphibians (Rana dybowskii).

Ovarian oocytes of Rana dybowskii, isolated early in the hibernation period (late autumn), failed to mature, i.e., germinal vesicle breakdown (GVBD), in response to progesterone during in vitro follicle culture. Oocytes collected during the middle hibernation period matured in response to progesterone, whereas those collected late during the hibernation period (close to the breeding season) underwent spontaneous maturation without added hormone (Kwon et al., '89). The maturational response (GVBD) of oocytes, collected at the three stages of hibernation, to protein kinase C (PKC) activation was investigated and compared to that of progesterone stimulation. A phorbol ester, phorbol 12-myristate 13-acetate (TPA) was used for PKC activation. TPA addition to cultured follicles collected during the early or middle period of hibernation induced oocyte GVBD. The incidence of maturation (% GVBD) induced by TPA varied markedly between animals. TPA (10 microM) induced oocyte maturation in the presence or absence of follicle cells. The time course of the TPA-induced maturation was similar to that of progesterone-stimulated maturation (ED50, 7-9 h). TPA also accelerated the onset of maturation of the follicular oocytes exhibiting spontaneous in vitro maturation. Both TPA- and progesterone-stimulated maturation was blocked by treatment with cycloheximide (1 microgram/2 ml), forskolin (9 microM) (an adenylate cyclase stimulator), and verapamil (0.27 mM) (a calcium transport blocker). Treatment of oocytes with a calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) (100 microM) or a PKC inactivator 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7) (50 microM) likewise suppressed TPA- or progesterone-induced maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Effects of irrigation fluid on human menisci: an experimental comparison of water, normal saline, and glycine.

A technique has been developed to demonstrate the macroscopic morphology of collagen fiber arrangement in human menisci. It was observed that 0.9% normal saline solution removed the ground substance of the meniscus, leaving intact collagen bundles. This suggests that meniscal damage may occur as a direct result of using normal saline for irrigation during knee arthroscopy. Experiments were conducted using demineralized water and 1.5% glycine for comparison. The disruption of collagen fiber binding in the meniscus by normal saline is time and temperature dependent. Glycine solution causes fibroblast lysis and a lesser degree of collagen alteration. Demineralized water can cause edema in the fibroblast but no notable change in collagen fibers. None of the irrigation solutions tested has proved to be completely safe. Demineralized water is not the ideal solution but is preferable to normal saline or glycine solution, especially when it can be used in conjunction with electrosurgery.

Adult↗

PubMed1991

Isolation and identification of clostridia from the intestine of laboratory animals.

Quantitative and qualitative examination of faecal clostridia from laboratory mice, rats, hamsters and rabbits was carried out by using selective as well as nonselective culture techniques. The 364 isolates were identified where possible, to species level on the basis of physiological and biochemical characteristics. Most isolates from mice and rabbits were identified, i.e. 79.4% and 76.5%, respectively, while only 25.4% and 28.6% of isolates from rats and hamsters were characterized as described species. The most common species of the 16 identified were: C. coccoides, C. cocleatum and C. innocuum from mice; C. cocleatum, C. cochlearium and C. irregularis from rats; C. cocleatum and C. irregularis from hamsters; and C. aminovalericum and C. irregularis from rabbits. Unidentified Clostridium spp. were isolated from each animal species tested and were tentatively classified into 26 groups. None of these groups was found in more than one animal species in this study.

Animals↗

PubMed1991

A randomized, placebo-controlled trial of doxycycline: effect on the microflora of recurrent periodontitis lesions in high risk patients.

Twenty-seven patients with a recent history of periodontal abscesses and/or loss of gingival attachment level (GAL) despite active periodontal therapy were enrolled in a double-blind, randomized, placebo-controlled trial. Clinical measurements and subgingival scaling were performed every 2 months. When a site exhibited greater than or equal to 2 mm loss of GAL or a periodontal abscess, patients were administered either doxycycline at a dosage of 200 mg to start and 100 mg per day for 3 weeks, or a placebo. Clinical measurements of GAL and microbial analysis of subgingival plaque at study and control sites were made at the time of active disease and at intervals of 1 week and 7 months after completion of the drug regime. Plaque samples were screened for the presence of Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Bacteroides intermedius (Bi), Eikenella corrodens (Ec) and Fusobacterium nucleatum (Fn) by indirect immunofluorescence antibody technique and for spirochetes (Sp) using Ryu's stain. Based on presence or absence analysis of the sum scores of the 6 pathogens, both the placebo (n = 10) and the doxycycline groups (n = 17) exhibited similar scores at the time of detection of active disease (mean placebo = 2.38 +/- 0.32; mean doxycycline = 2.95 +/- 0.27; P = 0.18). One week after treatment, the probability of detection was unchanged in the placebo group (mean placebo = 3.14 +/- 0.47), but was significantly reduced in the doxycycline group (mean doxycycline = 1.77 +/- 0.26; P = 0.0002). Study (active) sites exhibited scores 2 to 3 times higher than control (inactive) sites before doxycycline treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1991

Development of epidemiological method for the Helicobacter pylori by polymerase chain reaction.

The polymerase chain reaction was used to develop a method for the detection of Helicobacter pylori, a causative agent of gastritis, as well as for the elucidation of its mode of transmission. A genomic library of Helicobacter pylori DNA in Escherichia coli JM109 was constructed by cloning Hind III-digested DNA fragments into plasmid vector pUC18. The nucleotide sequences from seven recombinant clones were determined and five sets of oligonucleotide primers were synthesized on the basis of the sequences from five clones (B4, B9, B10, C15 and I22). The PCR amplifications with these primers were performed using DNA samples from five strains of Helicobacter pylori, two Campylobacter spp. and eleven species of enteric bacteria. Amplifications of the target DNA fragments in all of 5 strains of Helicobacter pylori were observed from the PCR with primers derived from clone B4, B9, C15 and I22. When the specificity was checked with the DNA samples from 13 other bacteria as template DNA for the PCR, specific amplification that produced the correct size of the target DNA of Helicobacter pylori was shown only in the PCR with primers derived from clone B9 and C15. The detection limit in the PCR amplification, determined by the heat-lysis method, was 500 cells of Helicobacter pylori.

Base Sequence↗

PubMed1991

Percutaneous mitral valvuloplasty using the double balloon technique: immediate results and determinant factors of increasing mitral regurgitation.

Percutaneous mitral valvuloplasty (PMV) was successfully performed in 112 (95%) out of 118 patients (32 M, 80 F, mean age: 38 +/- 11 years) with mitral stenosis. There was a significant increase in the mitral valve area (MVA) from 0.9 +/- 0.2 to 2.0 +/- 0.7 cm2 p less than 0.0001, a decrease in the mean mitral gradient from 17 +/- 6 to 6 +/- 3 mmHg, p less than 0.001, and a rise in cardiac output from 4.3 +/- 0.8 to 4.8 +/- 1.2 L/min, p less than 0.001. The morphologic features of the mitral stenosis was evaluated using echocardiographic score. Patients with a low-score (less than or equal to 8) had more effective dilation of mitral stenosis compared to patients with a high-score over 8 (0.9 to 2.2 vs 0.8 to 1.6 cm2, p less than 0.001), despite the similar EBDA/BSA (effective balloon dilating area/body surface area). The patients with good results after PMV (MVA greater than or equal to 1.5 cm2) were more likely to be in normal sinus rhythm (p less than 0.0001), younger age (p less than 0.001), smaller left atrial size (p less than 0.05), and lower total echoscore (p less than 0.002), especially in leaflet mobility (p less than 0.02) and degree of calcification (p less than 0.002), compared to patients with relatively poor result after PMV (MVA less than 1.5 cm2). There were no differences in EBDA/BSA, calcification on fluoroscopy, and history of previous surgical commissurotomy between the 2 groups. Mitral regurgitation (MR) developed or increased in severity in 41 (37%) cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Normal standard of pubertal development in Singapore school children.

A cross sectional study of the pubertal status of normal school children in Singapore was performed in 1987. The results of the data analysis are presented as an update from the last survey performed in 1977. The norms of pubertal development in boys and girls are thus defined.

Adolescent↗

PubMed1990

Detection of articular defects using magnetic resonance imaging: an experimental study.

This study evaluates magnetic resonance imaging (MRI) in the detection of surgically created articular defects in bovine knees. A total of 26 articular defects was created in 2 fresh cadaveric cows' knees. The defects created include chondromalacic grade 2 defects, chondral and osteochondral defects from 3 to 15 mm in diameter. The knee joints were repaired in a normal saline bath to exclude air in the joint prior to MR scanning. T1 weighted spin echo (SE) images and 3D gradient echo (FISP 40 degrees 3D) images were obtained. The T1 weighted SE imaging technique detected 15 defects (57.7%) compared with FISP 3D imaging technique detection of 17 defects (65.4%). The two techniques combined enable 21 of 26 defects (80.8%) to be detected. The imaging techniques used in this study were not able to detect chondromalacic defects less than 10 mm in diameter, nor chondral defects less than 5 mm in diameter. However, small osteochondral defects of 3 mm in diameter are detectable provided the depth of the defect is not less than 10 mm. The FISP 3D imaging technique alone is more sensitive in detecting chondral defects. Both imaging techniques have similarly high sensitivities in detecting osteochondral defects. The imaging time for combined T1 weighted SE and FISP 3D sequence is short (16.5 mm) and this combined technique may be useful for MR scanning of knee joints suspected to have articular defects.

Animals↗

PubMed1990

Serological classification by monoclonal antibodies of Rickettsia tsutsugamushi isolated in Korea.

Antigenic types of 113 strains of Rickettsia tsutsugamushi isolated from Korean patients were analyzed by using murine polyclonal and monoclonal antibodies. The isolates can be classified in six groups according to their reaction to a panel of monoclonal antibodies. Nine isolates of group I were identified as the Gilliam serotype, and 13 isolates of groups II and III were identified as the Karp serotype. There were two groups that were considered to be a mixture of groups I and II or groups I and III, respectively. The remaining 88 strains of group IV had a unique antigenic determinant that was not present in the prototype strains (Karp, Kato, Gilliam), in addition to sharing common antigens with the prototype strains. Therefore these strains, which are more prevalent in Korea, seem to belong to a new serotype closely related to the Karp serotype.

Animals↗

PubMed1987

Comparison of four leukocyte differential methods with the National Committee for Clinical Laboratory Standards (NCCLS) reference method.

The authors compared four leukocyte differential counting methods with the National Committee for Clinical Laboratory Standards Reference Leukocyte Differential Method H20-T to determine the clinical sensitivity of the methods. The three-part differential performed by the Coulter Counter Model S-Plus IV and the Toa E-5000, when combined with instrument flags and defined laboratory checking limits for red blood cell and platelet values, are safe and efficacious screening methods for the presence of morphologic abnormalities. The Geometric Data Hematrak 590 proved comparable in clinical sensitivity to a random 100-cell eye-count differential.

Adolescent↗

PubMed1987

Evaluation of the Toa E-5000 Automated Hematology Analyzer.

A three-phase evaluation of the Toa E-5000 Automated Hematology Analyzer was performed. The first phase consisted of evaluation of linearity, carryover, precisions, accuracy, sample stability, and effectiveness of the mixing and sampling mechanism. The second phase was comparison of erythroid and platelet parameters with results from a Coulter Counter Model S-Plus IV. The third phase consisted of comparison of the trimodal leukocyte differential count of the Toa E-5000 in 300 patients with four other differential methods. The first-phase studies showed excellent performance characteristics. Stability of samples at room temperature was good for a minimum of 12 hours, but storage for longer than 12 hours requires refrigeration to maintain stable values. The erythrocyte and platelet parameters showed good correlation with the Coulter S-Plus IV values except for the erythrocyte distribution width that is calculated differently. The third-phase studies are published elsewhere.

Autoanalysis↗

PubMed1987

Intestinal bacteria antagonistic to Clostridium difficile in mice.

Overgrowth by Clostridium difficile has been reported in conventional mice injected intraperitoneally with ampicillin. In this study, we aimed to determine which types of indigenous intestinal bacteria were eliminated by ampicillin to allow overgrowth by C. difficile. C. difficile overgrowth was associated with a decrease in the numbers of lactobacilli, an increase in bacteroidaceae and a slight decrease in the frequency of isolation of fusiform-shaped bacteria (clostridia). C. difficile cytotoxin was detected in caeca from mice in which the numbers of C. difficile were greater than 10(5) per gram of faeces. Gnotobiotic mice were inoculated with various groups of intestinal anaerobes to determine which members of the indigenous flora would antagonize C. difficile. Gnotobiotic mice inoculated with three strains of lactobacilli, 37 strains of bacteroides or 46 strains of clostridia isolated from limited-flora mice were unable to eliminate C. difficile. C. difficile was eliminated, however, from the gastrointestinal tracts of gnotobiotic mice inoculated with whole faeces or chloroform-treated faeces from conventional mice or whole faeces from limited-flora mice containing only clostridia.

Ampicillin↗

PubMed1987

The frequency distribution of cardiovascular diseases in 13 hospital admitted patients in Korea. Korean Society of Circulation.

The frequency distribution of cardiovascular disease are changing recently due to the development of living environment. Unfortunately there are few epidemiological studies of cardiovascular diseases in general population, we tried to estimate the recent trend of cardiovascular diseases studying hospitalized patients in nationwide 13 large hospitals during a year of 1985. The hypertensive disease (24.1%) was the most common cardiovascular disease and the next were cerebrovascular disease (15.8%), arrhythmias (12.2%), ischemic heart disease (9.7%), congenital heart disease (9.1%), and rheumatic heart disease (5.4%) in order. This results showed that hypertensive disease and cerebrovascular disease are still the major cardiovascular disease and ischemic heart disease and arrhythmias are increased. But chronic rheumatic heart disease is declined compared with previous studies in hospitalized patients.

Adolescent↗