Biomedical subjects

M H Lee

Publications and source records attributed to M H Lee.

At least 145 records · Page 8Linked to original sources

PubMed2000

Simultaneous determination of aceclofenac and diclofenac in human plasma by narrowbore HPLC using column-switching.

A fully automated narrowbore high performance liquid chromatography (HPLC) with column-switching was developed for the simultaneous determination of aceclofenac and diclofenac from human plasma samples. Plasma sample (100 microl) was directly introduced onto a Capcell Pak MF Ph-1 column (20 x 4 mm I.D.) where primary separation was occurred to remove proteins and concentrate target substances using acetonitrile potassium phosphate (pH 7, 0.1 M) (14:86, v/v). The drug molecules eluted from MF Ph-1 column were focused in an intermediate column (35 x 2 mm I.D.) by the valve switching step. The substances enriched in intermediate column were eluted and separated on the narrowbore phenyl hexyl column (100 x 2 mm I.D.) using acetonitrile-potassium phosphate (pH 7, 0.02M) (33:67, v/v) when the valve status was switched back to A position. The method showed excellent sensitivity (detection limit of 10 ng ml(-1)) with small volume of samples (100 microl), good precision and accuracy, and speed (total analysis time 17 min) without any loss in chromatographic efficiency. The response was linear (r2 > or = 0.999) over the concentration range of 50-10,000 ng ml(-1).

Adult↗

PubMed2000

Citrus red mite (Panonychus citri) is a common sensitizing allergen among children living around citrus orchards.

BACKGROUND: A recent investigation has suggested that Panonychus citri (citrus red mite) is the most common causative allergen in citrus-cultivating farmers with asthma or allergic rhinitis. OBJECTIVE: A cross-sectional survey was performed to evaluate the prevalence of asthma and sensitization to P. citri among children living around citrus orchards. METHODS: A total of 1,055 children living around citrus orchards were enrolled. There were 544 boys and 511 girls with a mean age of 12.3 (range 7 to 16) years. They were evaluated by the ISAAC questionnaire, and a skin prick test with 13 common aeroallergens including P. citri and Japanese cedar pollen. Children who recorded ever having experienced wheezing on the questionnaire were evaluated by methacholine bronchial provocation test and determined to have asthma if they showed bronchial hyperresponsiveness to methacholine simultaneously. RESULTS: The positive skin test response to one or more inhalant allergens except P. citri was 35.5%, but when including P. citri, the positive response increased to 37.7%. The most common sensitizing allergens in the order of decreasing frequency were Dermatophagoides pteronyssinus (26.6%), D. farinae (22.7%), P. citri (14.2%), cockroach (11.3%), and Japanese cedar pollen (9.7%). Among the children without sensitization to house dust mites, the sensitization rate to P. citri was significantly higher in those 13 and over than in those under 12 (5.8% versus 2.5%, P < .05). The prevalence of asthma was not different between the children with sensitization to P. citri and those without it (5.4% versus 4.0%, P > .05), although the prevalence was higher in those with sensitization to D. pteronyssinus or D. farinae than in those without sensitization to these allergens (7.9% versus 2.9%, P < .05; 9.7% versus 2.6%, P < .05). CONCLUSION: Citrus red mite is a common sensitizing allergen among children living around citrus orchards. The features of sensitization and development of asthma are different between citrus red mite and house dust mites.

Administration, Inhalation↗

PubMed2000

Bronchial responsiveness to methacholine is increased in citrus red mite (Panonychus citri)-sensitive children without asthmatic symptoms.

BACKGROUND: A recent investigation has suggested that citrus red mite (Panonychus citri, CRM) is a common sensitizing allergen among children living around citrus farms. OBJECTIVE: A cross-sectional survey was performed to evaluate the bronchial responsiveness to methacholine in CRM-sensitive children without asthmatic symptoms. SUBJECTS AND METHODS: A total of 375 children living around citrus farms were enrolled in this study. There were 201 boys and 174 girls with a mean age of 12.5 (range 7-16) years. Each subject was evaluated by a questionnaire, a skin prick test with 13 common inhalant allergens including CRM, and a methacholine bronchial provocation test (MBPT). RESULTS: Positive rate of MBPT (PC20-methacholine < 25 mg/mL) was higher in atopic rhinitic and atopic control children than in nonatopic rhinitic and nonatopic control subjects (41.3% and 33.3% vs 17.2% and 15.4%, respectively, both P < 0.05). Slope of dose-response curve (DRS, %/mg/mL) was higher in atopic rhinitic children than in nonatopic rhinitic, atopic control and nonatopic control subjects (14.3 +/- 0.87 vs 9.4 +/- 0.72, 10.0 +/- 1.37 and 9.2 +/- 1.51, P < 0.05, respectively). Both the positive rate of MBPT and the DRS were increased in children with positive skin response to CRM than in those without sensitization (48.2% vs 22.9%, P = 0.0001; 15.6 +/- 1.26 vs 10.2 +/- 0.65, P = 0.0001). CONCLUSION: Bronchial responsiveness is increased in citrus red mite-sensitive children even if they have no asthmatic symptoms.

Adolescent↗

PubMed2000

Association of HLA-DRB1()07 and DRB1()04 to citrus red mite (Panonychus citri) and house dust mite sensitive asthma.

BACKGROUND: Specific IgE responses to allergens provide useful models for evaluating the genetic factors that control human immune responses. A recent survey demonstrated that the citrus red mite (Panonychus citri, CRM) is the most important allergen in the development of asthma in citrus farmers. OBJECTIVE: The aim of this study was to evaluate whether susceptibility or resistance to CRM-induced asthma was associated with HLA-DRB1 gene. METHODS: DNAs were extracted from two groups of unrelated Korean adults living around citrus farms: (1) Ninety-one adults with CRM-sensitive asthma; and (2) 98 exposed, healthy nonatopic controls. Genotypes of HLA-DRB1 alleles were carried out using PCR-based methods. RESULTS: Allelic frequency of HLA-DRB1(*)07 was higher in the CRM-sensitive asthmatics compared to the controls (17.6% vs 4.1%, Pc = 0.01). Conversely, the frequency of DRB1*04 was lower in the CRM-sensitive asthmatics compared to the controls (19.8% vs 40.8%, Pc = 0.01). No significant difference was found in the distributions of the other HLA-DRB1 gene-encoded antigens between the two groups. CONCLUSION: HLA-DRB1 genes may be involved in the development of CRM-induced asthma. In addition, HLA-DR7 may increase, and DR4 decrease, the risk of developing the asthma in CRM-exposed adults.

Adult↗

PubMed2000

In vivo rapid reduction of alloantigen-activated CD8+ mature cytotoxic T cells by inhibitors of acidification of intracellular organelles, prodigiosin 25-C and concanamycin B.

Prodigiosin (PrG) 25-C and concanamycin B (CMB) are immunosuppressants that specifically inhibit the induction of cytotoxic T cells (CTL) without affecting the function of B cells and helper T cells in vivo. Both compounds inhibit acidification of intracellular organelles and induce destruction of cytotoxic granules and degradation of perforin in vitro. Here we show that a single intraperitoneal (i.p.) injection of PrG 25-C, and of CMB, into mice eliminates cytotoxic activity 7 days after alloantigen stimulation (when mature CTL activity has been detected in control mice), with minimal effect on the alloantigen-specific antibody titre in serum. FK506 did not suppress the cytotoxic activity with this administration schedule. Suppression was accompanied by a decrease in the CD8+ population and in perforin expression of spleen cells induced by alloantigen stimulation. The suppression of CTL activity and decrease in CD8+ cell number was detected as early as 7 hr after the injection of compounds. These results suggest that inhibitors of acidification of intracellular organelles suppress CTL activity in vivo by reducing the number of mature CD8+ CTL.

Animals↗

PubMed2000

The clinical significance of upper gastrointestinal endoscopy in gastrointestinal vasculitis related to scrub typhus.

BACKGROUND AND STUDY AIMS: Scrub typhus is an acute febrile illness caused by Rickettsia tsutsugamushi-induced vasculitis, which is common in Asia and the Pacific islands and is sometimes encountered in Western countries because of increased travel and economic changes spurred by world globalization. Skin rash and eschar are typical physical findings on the trunk and extremities, but endoscopic mucosal changes have not been described in the gastrointestinal tract until now. We aimed to describe different endoscopic characteristics of the gastrointestinal manifestation of scrub typhus, to ascertain the necessity for endoscopy, and to determine correlations between the degrees of endoscopic lesion and clinical severity, including cutaneous manifestation. PATIENTS AND METHODS: Between January 1993 and October 1998, out of 256 scrub typhus patients, we applied esophagogastroduodenoscopy to 58 patients who complained of gastrointestinal symptoms but had no past history of these symptoms. We categorized clinical severity into four grades according to the degree of six clinical indicators of systemic complications, and endoscopic findings were graded from I to IV (I, normal, nonspecific hyperemia; II, distinct hyperemia, petechiae, purpura; II, superficial hemorrhage, erosion; IV, ulcer, active bleeding). RESULTS: Endoscopic findings of scrub typhus were characterized by petechiae, superficial hemorrhage, erosion, ulcers, and vascular bleeding (grade I, 14 patients; grade II, 11 patients; grade III, 16 patients; grade IV, 17 patients). In 83.3% of patients there was multiple occurrence of lesions without any predilection sites. Clinical severity was graded (grade I, 7 patients; grade II, 23 patients; grade III, 22 patients; grade IV, 6 patients). There was a correlation between clinical severity and endoscopic findings (P < 0.01). The grade of lesion was high in patients with cutaneous lesions (r(s) 0.359, P < 0.01). In two cases of gastric vascular bleeding, complete hemostasis was achieved by endoscopic hemoclipping. CONCLUSIONS: The major endoscopic features that can develop in scrub typhus are superficial mucosal hemorrhage, multiple erosions and ulcers without any predilection sites, and unusual vascular bleeding. The endoscopic features are related to cutaneous lesions and severity of the disease. Endoscopy is useful for diagnosis and management of gastrointestinal vasculitis related to scrub typhus.

Endoscopy, Gastrointestinal↗

PubMed2000

Bleeding Dieulafoy's lesions and the choice of endoscopic method: comparing the hemostatic efficacy of mechanical and injection methods.

BACKGROUND: Dieulafoy's lesion has unique endoscopic and histopathologic characteristics. This is a clinical trial of endoscopic therapy in 24 patients with Dieulafoy's lesions. METHODS: Patients were divided into 2 groups according to initial endoscopic treatment method. Data were analyzed with respect to clinical and endoscopic characteristics as well as outcomes. The 24 patients were evenly divided into mechanical (9 hemoclipping, 3 band ligation) and injection groups (12). RESULTS: The average number of therapeutic endoscopic sessions needed to achieve permanent hemostasis for the mechanical and injection groups were 1.17 and 1.67, respectively. Initial hemostasis was achieved in 91.7% of patients undergoing mechanical therapy and 75% of those undergoing injection therapy, with none in the former group needing subsequent surgery in comparison to 17% of the latter group. The rate of recurrent bleeding in the mechanical therapy group was significantly lower in comparison to the injection therapy group (8.3% versus 33.3%, p < 0. 05). CONCLUSIONS: Higher efficacy in terms of initial hemostasis and less recurrent bleeding was achieved by mechanical hemostatic therapy with hemoclip and band ligation compared with injection therapy. Endoscopic mechanical therapy is recommended as effective for bleeding Dieulafoy's lesions.

Adult↗

PubMed2000

A WEB-based telePACS using an asymmetric satellite system.

We have developed a WWW-based TelePACS that can access every permitted PACS server via the Internet. Java programming techniques were used to implement the system, which can access and retrieve medical information and images through Web browsers only such as Netscape without specific tools. We also have developed a consolidator that performs as a manager to connect a conventional PACS server to a Web-based TelePACS server. We have developed the Asymmetric Satellite Data Communication System (ASDCS) as a fast communication system. The ASDCS uses a receive-only satellite link for data delivery and a terrestrial network for control communication. In conclusion, we were able to develop a cost-effective and fast PACS using Web technology. Web technology expanded the scope of use for a dedicated PACS from intrahospital to public use.

Humans↗

PubMed2000

Pedunculated atypical cellular blue nevus.

Atypical variants of cellular blue nevus are considered to have features intermediate between typical cellular blue nevus and rare malignant blue nevus; they usually show bizarre pleomorphic cells which have prominent nucleoli. We describe a 37-year-old-Korean woman who had had an asymptomatic pedunculated single mass on her right thigh for 17 years. A skin biopsy showed a tumor consisting of intensely pigmented dendritic cells and less or nonpigmented epitheloid cells in the dermis with striking atypia. There has been no evidence of recurrence for 3 years after surgery. The diagnosis of atypical cellular blue nevus was made on the basis of clinical features and skin biopsy findings.

Adult↗

PubMed2000

Comparing cardiac action potentials recorded with metal and glass microelectrodes.

Machine-pulled high-impedance glass capillary microelectrode is standard for transmembrane potential (TMP) recordings. However, it is fragile and difficult to impale, especially in beating myocardial tissues. We hypothesize that a high-impedance pure iridium metal electrode can be used as an alternative to the glass microelectrode for TMP recording. The TMPs were simultaneously recorded from isolated perfused swine right ventricles with a metal microelectrode and a standard glass microelectrode during pacing and during ventricular fibrillation. The basic morphology of TMP recorded with these electrodes was comparable. The action potential duration (APD) at 90% repolarization was 241 +/- 29 ms for the metal microelectrode and 236 +/- 31 ms for the glass microelectrode with a good correlation (r = 0.99, P < 0.0001). The maximum slope value of the APD restitution curves during pacing was also significantly correlated. One metal microelectrode and >20 glass microelectrodes were needed per study. We conclude that, in isolated perfused swine right ventricles, the TMP recorded by the metal microelectrode is comparable with that recorded by the glass microelectrode. Because the metal microelectrode is more durable than the glass microelectrode, it can serve as an alternative for APD recording and for restitution analyses.

Action Potentials↗

PubMed2000

FOG-2, a novel F-box containing protein, associates with the GLD-1 RNA binding protein and directs male sex determination in the C. elegans hermaphrodite germline.

Male sex determination in the Caenorhabditis elegans hermaphrodite germline requires translational repression of tra-2 mRNA by the GLD-1 RNA binding protein. We cloned fog-2 by finding that its gene product physically interacts with GLD-1, forming a FOG-2/GLD-1/tra-2 3'untranslated region ternary complex. FOG-2 has an N-terminal F-box and a novel C-terminal domain called FTH. Canonical F-box proteins act as bridging components of the SCF ubiquitin ligase complex; the N-terminal F-box binds a Skp1 homolog, recruiting ubiquination machinery, while a C-terminal protein-protein interaction domain binds a specific substrate for degradation. However, since both fog-2 and gld-1 are necessary for spermatogenesis, FOG-2 cannot target GLD-1 for ubiquitin-mediated degradation. We propose that FOG-2 also acts as a bridge, bringing GLD-1 bound to tra-2 mRNA into a multiprotein translational repression complex, thus representing a novel function for an F-box protein. fog-2 is a member of a large, apparently rapidly evolving, C. elegans gene family that has expanded, in part, by local duplications; fog-2 related genes have not been found outside nematodes. fog-2 may have arisen during evolution of self-fertile hermaphroditism from an ancestral female/male species.

3' Untranslated Regions↗

PubMed2000

A radio controller using speech for the blind.

This article describes a low-cost, portable real-time DSP-based speech controller system to provide radio interface control command applications for the blind. The system recognizes spoken Mandarin Chinese words on a DSP chip (TMS320C31) using a hidden Markov model. The function of the radio set, which includes a tuner, tape, and compact disc, were evaluated under both noisy and noiseless environments. Four subjects took part in the experiment and achieved 83 and 90% mean recognition rates under noisy and noiseless conditions, respectively. In addition, because this system is based on a DSP chip, it can easily be programmed to execute speaker-independent algorithms.

Algorithms↗

PubMed2000

Decreased oral bioavailability of loxoprofen at second administration in human subjects.

The objective of this study was to determine the extent of period effect on the pharmacokineitcs of loxoprofen during consecutive dosing. Loxipen and Loxonin tablets were administered to 16 healthy Korean male subjects at a single dose of 60 mg as loxoprofen sodium anhydrous in a 2 x 2 crossover investigation with a two-week wash-out phase. Concentrations of loxoprofen in plasma were measured by HPLC method for 6 h. The two formulations were found bioequivalent, but analysis of variance (ANOVA) indicated that there was a significant (p < 0.05) period effect in AUCinf (area under the plasma concentration-time curve from time zero to infinity) between the administrations. A 20% decrease in the AUC was seen at the second administration. This period effect on pharmacokinetics of loxoprofen may be relevant for the patients who need consecutive administration of the drug.

Administration, Oral↗

PubMed2000

Microsomal triglyceride transfer protein expression during mouse development.

Feto-maternal transfer of lipophilic nutrients is an important factor in the normal development of the fetus and may be mediated by lipoproteins as carriers of these nutrients. Two proteins that may be important in this process are apolipoprotein B (apoB, the major structural protein of secreted lipoproteins) and microsomal triglyceride transfer protein (MTP) whose normal activity is required for the secretion of apoB-containing lipoproteins. Although no abnormalities of conception and embryonic lethality are known in humans who inherit genetic deficiencies of either of these proteins, homozygous mice bearing knockouts of either apoB or MTP show early embryonic lethality. To characterize the ontogeny of MTP expression during embryonic mouse development, we have used in situ hybridization to characterize the pattern of expression. By using microwave heating of tissue sections to optimize hybridization, we show that there is robust MTP expression in the yolk sac tissues followed by expression in the primordial liver cell nests as early as day 9 post-coitum (E9.5). Intestinal expression is detected around E12.5 and attains full adult expression patterns by E14.5. No expression in any other tissues was observed, including developing heart, kidney, placenta, and maternal decidua. Thus the pattern of MTP expression is compatible with a role in the transfer of lipophilic nutrients from the yolk sac, prior to hepatic development and to the liver, once the circulatory system has been established.

Animals↗

PubMed2000

Short-term vestibular responses to repeated rotations.

To investigate the short-term vestibular habituation, we performed the 4 successive velocity step tests on 28 volunteers, the peak velocity of which was 100 deg/sec with acceleration and deceleration of 100 deg/sec2. As the repeated rotations might alter the vestibulo-ocular reflex (VOR), sinusoidal rotations at a frequency of 0.16 Hz were also given before and after the 4 successive velocity step tests to investigate the changes of gain and phase of VOR. The 28 volunteers were divided into two groups, group I and II, according to their responses to repeated rotations. In group I (25 subjects, mean age 23.7 year), the mean values of the slow cumulative eye position (SCEP), the time integral of eye velocity during nystagmus, was reduced after each trial of the 4-successive velocity step tests as follows; 403.4 +/- 29 degree (1st trial), 346.2 +/- 37 degree (2nd trial), 278.3 +/- 33 degree (3rd trial) and 256.6 +/- 36 degree (4th trial). The time constant of the nystagmus was also reduced as follows; 12.9 +/- 0.78 second (1st trial), 12 +/- 0.63 second (2nd trial), 9.7 +/- 0.78 second (3rd trial) and 9.9 +/- 0.54 second (4th trial). In group II (3 subjects, mean age 28.3 year), the mean values of SCEP gradually increased; 774.3 +/- 135 degree (1st trial), 1127 +/- 178 degree (2nd trial), 1096.3 +/- 123.4 degree (3rd trial) and 1225.7 +/- 199.7 degree (4th trial). The time constant of the nystagmus increased; 15.7 +/- 2.7 second (1st trial), 22 +/- 4.5 second (2nd trial), 22.3 +/- 3.3 second (3rd trial) and 23.3 +/- 5.7 second (4th trial). The gain of vestibulo-ocular reflex (VOR) induced by sinusoidal rotations at a frequency 0.16 Hz increased in both groups: 0.59 +/- 0.03 to 0.78 +/- 0.06 (group I) and 0.65 +/- 0.07 to 1.15 +/- 0.06 (group II). Phase changes were also observed. In group I, the phase was shifted from 0.6 +/- 0.6 degree to -0.40 +/- 0.6 degree. In group II, the phase was shifted from 3.67 +/- 1.86 degree to -0.33 +/- 0.33 degree. The repeated rotation did not induce a common nystagmic response in all subjects. Thus, person to person variations should be considered in short term vestibular habituation.

Adult↗

PubMed2000

Combined periodontal-prosthodontic treatment of early-onset periodontitis--an alternative to implant therapy.

A variety of treatment systems should be available for patients whose dentitions are seriously compromised so that they may select customized treatment modalities that satisfactorily restore occlusal function, consider systemic conditions, and lessen the surgical and financial burdens. These requirements become more demanding when clinicians are faced with advanced cases of rapidly progressive periodontitis. Therefore, it is critical to establish sophisticated multidisciplinary treatment modalities for the successful management of these compromised patients. Obviously, because of various limitations, implant therapy cannot be the only solution. This article reports on the successful long-term management of seriously compromised early-onset periodontitis by a combined periodontal-prosthetic treatment as an alternative to implant therapy.

Adult↗

PubMed2000

Expression and characterization of the flavoprotein domain of gp91phox.

Truncated forms of gp91(phox) were expressed in E. coli in which the N-terminal hydrophobic transmembrane region was replaced with a portion of the highly soluble bacterial protein thioredoxin (TRX). TRX-gp91(phox) (306-569), which contains the putative FAD and NADPH binding sites, showed NADPH-dependent NBT (nitroblue tetrazolium) reductase activity, whereas TRX-gp91(phox) (304-423) and TRX-gp91(phox) (424-569) were inactive. Activity saturated at about a 1:1 molar ratio of FAD to TRX-gp91(phox) (306- 569), and showed the same Km for NADPH as that for superoxide generating activity by the intact enzyme. Activity was not inhibited by superoxide dismutase, indicating that it was not mediated by superoxide, but was blocked by an inhibitor of the respiratory burst oxidase, diphenylene iodonium (DPI). In the presence of Rac1, the cytosolic regulatory protein p67(phox) stimulated the NBT reductase activity, but p47(phox) had no effect. Truncated p67(phox) containing the activation domain (residues 199- 210) stimulated activity approximately 2-fold, whereas forms mutated or lacking this region failed to stimulate the activity. Our data indicate that: 1) TRX-gp91(phox) (306-569) contains the binding sites for both pyridine and flavin nucleotides; 2) this flavoprotein domain shows NBT reductase activity; and 3) the flavin-binding domain of gp91(phox) is the target of regulation by the activation domain of p67(phox).

Animals↗

PubMed2000

Activation domain in P67phox regulates the steady state reduction of FAD in gp91phox.

An activation domain in p67(phox) (residues 199-210) is critical for regulating NADPH oxidase activity in cell-free system [10] To determine the steady state reduction of FAD, thioacetamide-FAD was reconstituted in gp91(phox), and the fluorescence of its oxidised form was monitored. Omission of p67(phox) decreased the steady state reduction of the FAD from 28% to 4%, but omission of p47(phox) had little effect. A series of the truncated forms of p67(phox) were expressed in E.coli to determine the domain in p67(phox) which is essential for regulating the steady state of FAD reduction. The minimal length of p67(phox) for for regulating the steady state of FAD reduction is shown to be 1-210 using a series of truncation mutants which indicates that the region 199-210 is also important for regulating electron flow within flavocytochrome b(558). The deletion of this domain not only decreased the superoxide generation but also decreased the steady state of FAD reduction. Therefore, the activation domain on p67(phox) regulates the reductive half-reaction for FAD, consistent with a dominant effect on hydride/electron transfer from NADPH to FAD.

Amino Acid Sequence↗