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Teoh SE, Tan EWX, Teo YN, Basker G, Teo YH, Chai P, Wong RCC, Yip JWL, Kuntjoro I, Lim YH, Poh KK, Yeo TC, Kong WKF, Sia CH. Effects of medical therapy, transcatheter intervention, and surgery on outcomes of patients with functional mitral regurgitation: a systematic review and network meta-analysis. Eur Heart J 2023. [DOI: 10.1093/eurheartj/ehac779.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Public Institution(s). Main funding source(s): Ching-Hui Sia was supported by the National University of Singapore Yong Loo Lin School of Medicine's Junior Academic Fellowship Scheme.
Background
Functional mitral regurgitation (FMR) is the most common valvular heart disease worldwide. Despite recent major trials, the relative efficacy between medical therapy, transcatheter intervention, and surgery for the treatment of FMR remains poorly understood.
Purpose
We performed a systematic review and network meta-analysis of all published randomised controlled trials (RCTs) and observational studies to compare the efficacy between medical therapy, transcatheter intervention, and surgery on the clinical outcomes of patients with FMR.
Methods
Four electronic databases (PubMed, EMBASE, SCOPUS, and the Cochrane Library) were searched from inception to March 13, 2022, for studies reporting clinical outcomes in patients with FMR and comparing the efficacy between either medical therapy, transcatheter intervention, or surgery. Frequentist network meta-analysis models were utilised to summarise the studies. This study was registered in the International Prospective Register of Systematic Reviews.
Results
10 articles were included in the analysis, comprising a combined cohort of 1,981 patients. Network meta-analysis demonstrated that compared to medical therapy, transcatheter intervention achieved a lower relative risk in the composites of all-cause mortality (risk ratio [RR]: 0.43; 95% confidence interval [CI] 0.22-0.82) and mitral regurgitation (MR) severity grade ≥3+ (RR: 0.06; 95% CI 0.01-0.42). Compared to surgery, transcatheter intervention achieved a lower relative risk in the composites of cardiovascular death (RR: 0.36; 95% CI 0.17-0.75) and MR severity grade ≥3+ (RR: 0.25; 95% CI 0.09-0.70) and higher relative risk in the composite of heart failure hospitalisation (RR: 2.94; 95% CI 1.26-6.82). Compared to medical therapy, surgery achieved a higher relative risk in the composite of cardiovascular death (RR: 2.54; 95% CI 1.18-5.47) and lower relative risks in the composites of all-cause mortality (RR: 0.56; 95% CI 0.34-0.91) and heart failure hospitalisation (RR: 0.28; 95% CI 0.13-0.61).
Conclusion
Medical therapy, transcatheter intervention, and surgery in patients with FMR displayed differing effects on the various clinical outcomes. Further head-to-head trials are required to better understand the optimal treatment modality in this population.
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Affiliation(s)
- S E Teoh
- National University of Singapore, Yong Loo Lin School of Medicine , Singapore , Singapore
| | - E W X Tan
- National University of Singapore, Yong Loo Lin School of Medicine , Singapore , Singapore
| | - Y N Teo
- National University of Singapore, Yong Loo Lin School of Medicine , Singapore , Singapore
| | - G Basker
- National University of Singapore, Yong Loo Lin School of Medicine , Singapore , Singapore
| | - Y H Teo
- National University of Singapore, Department of Medicine , Singapore , Singapore
| | - P Chai
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - R C C Wong
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - J W L Yip
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - I Kuntjoro
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - Y H Lim
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - K K Poh
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - T C Yeo
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - W K F Kong
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
| | - C H Sia
- National University Heart Centre, Department of Cardiology , Singapore , Singapore
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Bergmann ML, Andersen ZJ, Amini H, Khan J, Lim YH, Loft S, Mehta A, Westendorp RG, Cole-Hunter T. Ultrafine particle exposure for bicycle commutes in rush and non-rush hour traffic: A repeated measures study in Copenhagen, Denmark. Environ Pollut 2022; 294:118631. [PMID: 34871646 DOI: 10.1016/j.envpol.2021.118631] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 06/13/2023]
Abstract
Ultrafine particles (UFP), harmful to human health, are emitted at high levels from motorized traffic. Bicycle commuting is increasingly encouraged to reduce traffic emissions and increase physical activity, but higher breathing rates increase inhaled UFP concentrations while in traffic. We assessed exposure to UFP while cycling along a fixed 8.5 km inner-city route in Copenhagen, on weekdays over six weeks (from September to October 2020), during morning and afternoon rush-hour, as well as morning non-rush-hour, traffic time periods starting from 07:45, 15:45, and 09:45 h, respectively. Continuous measurements were made (each second) of particle number concentration (PNC) and location. PNC levels were summarized and compared across time periods. We used generalized additive models to adjust for meteorological factors, weekdays and trends. A total of 61 laps were completed, during 28 days (∼20 per time period). Overall mean PNC was 18,149 pt/cm3 (range 256-999,560 pt/cm3) with no significant difference between morning rush-hour (18003 pt/cm3), afternoon rush-hour (17560 pt/cm3) and late morning commute (17560 pt/cm3) [p = 0.85]. There was substantial spatial variation of UFP exposure along the route with highest PNC levels measured at traffic intersections (∼38,000-42000 pt/cm3), multiple lane roads (∼38,000-40000 pt/cm3) and construction sites (∼44,000-51000 pt/cm3), while lowest levels were measured at smaller streets, areas with open built environment (∼12,000 pt/cm3), as well as at a bus-only zone (∼15,000 pt/cm3). UFP exposure in inner-city Copenhagen did not differ substantially when bicycling in either rush-hour or non-rush-hour, or morning or afternoon, traffic time periods. UFP exposure varied substantially spatially, with highest concentrations around intersections, multiple lane roads, and construction sites. This suggests that exposure to UFP is not necessarily reduced by avoiding rush-hours, but by avoiding sources of pollution along the bicycling route.
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Affiliation(s)
- M L Bergmann
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
| | - Z J Andersen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - H Amini
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - J Khan
- Atmospheric Modelling Research Group, Department of Environmental Science, Aarhus University, Roskilde, Denmark; Danish Big Data Centre for Environment and Health (BERTHA), Aarhus University, Roskilde, Denmark
| | - Y H Lim
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - S Loft
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - A Mehta
- Section of Epidemiology, Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Statistics Denmark, Copenhagen, Denmark
| | - R G Westendorp
- Department of Public Health and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - T Cole-Hunter
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
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Bergmann ML, Andersen ZJ, Amini H, Ellermann T, Hertel O, Lim YH, Loft S, Mehta A, Westendorp RG, Cole-Hunter T. Exposure to ultrafine particles while walking or bicycling during COVID-19 closures: A repeated measures study in Copenhagen, Denmark. Sci Total Environ 2021; 791:148301. [PMID: 34412377 PMCID: PMC8178061 DOI: 10.1016/j.scitotenv.2021.148301] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/27/2021] [Accepted: 06/01/2021] [Indexed: 05/15/2023]
Abstract
Ultrafine particles (UFP; particulate matter <0.1 μm diameter) emitted from motorized traffic may be highly detrimental to health. Active mobility (walking, bicycling) is increasingly encouraged as a way to reduce traffic congestion and increase physical activity levels. However, it has raised concerns of increased exposure to UFP, due to increased breathing rates in traffic microenvironments, immediately close to their source. The recent Coronavirus Disease 2019 (COVID-19) societal closures reduced commuting needs, allowing a natural experiment to estimate contributions from motorized traffic to UFP exposure while walking or bicycling. From late-March to mid-July 2020, UFP was repeatedly measured while walking or bicycling, capturing local COVID-19 closure ('Phase 0') and subsequent phased re-opening ('Phase 1', '2', '2.1' & '3'). A DiSCmini continuously measured particle number concentration (PNC) in the walker/bicyclist's breathing zone. PNC while walking or bicycling was compared across phased re-openings, and the effect of ambient temperature, wind speed and direction was determined using regression models. Approximately 40 repeated 20-minute walking and bicycling laps were made over 4 months during societal re-opening phases related to the COVID-19 pandemic (late-March to mid-July 2020) in Copenhagen. Highest median PNC exposure of both walking (13,170 pt/cm3, standard deviation (SD): 3560 pt/cm3) and bicycling (21,477 pt/cm3, SD: 8964) was seen during societal closures (Phase 0) and decreased to 5367 pt/cm3 (SD: 2949) and 8714 pt/cm3 (SD: 4309) in Phase 3 of re-opening. These reductions in PNC were mainly explained by meteorological conditions, with most of the deviation explained by wind speed (14-22%) and temperature (10-13%). Highest PNC was observed along major roads and intersections. In conclusion, we observed decreases in UFP exposure while walking and bicycling during societal re-opening phases related to the COVID-19 pandemic, due largely to meteorological factors (e.g., wind speed and temperature) and seasonal variations in UFP levels.
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Affiliation(s)
- M L Bergmann
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
| | - Z J Andersen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - H Amini
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - T Ellermann
- Department of Environmental Science, Aarhus University, Roskilde, Denmark
| | - O Hertel
- Department of Bioscience, Aarhus University, Roskilde, Denmark
| | - Y H Lim
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - S Loft
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - A Mehta
- Section of Epidemiology, Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Statistics Denmark, Copenhagen, Denmark
| | - R G Westendorp
- Department of Public Health and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - T Cole-Hunter
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
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Lee Y, Park HC, Shin JH, Lim YH, Park JK, Shin J, Kim KS, Kim BK. P5298Influence of the changes in body fat on all-cause and cardiovascular mortality in a general population: a report from Ansan-Ansung cohort in the Korean genome environment study. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz746.0269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Paradoxical beneficial effects of obesity on all-cause and cardiovascular mortality have been reported in multiple cohort studies based on patients with cardiovascular disease as well as general populations. However, the association between the presence of obesity at baseline and the better survival rates could not be directly interpreted into the beneficial effect of gain in obesity or fatness on the mortality, which makes it difficult to provide any recommendation for the management of obesity. Therefore, we investigated the influence of the changes in body fat on all-cause and cardiovascular mortality in a general population.
Methods
A population-based cohort study has been conducted for 12 years (from 2001 to 2012). A total of 5,259 subjects in whom body compositions using a bio-impedance method were measured at least 2 times during the observational period were included. The causes of death was identified from the nation-wide database in KOSTAT. I20-I82 and R99 in the International Classification of Disease-10 codes were defined as a cardiovascular death. The subjects were evenly divided into 3 groups by the percentages of the changes in body fat (Δ%BF; decreased [Δ%BF <0.0%] vs. increased [Δ%BF 0.0–13.7%] vs. highly increased [Δ%BF ≥13.7%]). Inverse probability of treatment weighting was applied to balance the covariate differences among the groups.
Results
The age was 51.2±8.5 years and 51.6% was male. Median observation duration was 163 (the interquartile range: 157–168) months. The all-cause death and cardiovascular death occurred most frequently in the decreased Δ%BF group and least frequent in the highly increased Δ%BF group in both unweighted and weighted cohort. Multivariate Cox proportional hazard models showed that the risk of all-cause death was lower in the increased and highly increased Δ%BF groups (hazard ratio [HR] 0.61 [0.47–0.80] and 0.24 [0.17–0.34], respectively) and the risk of cardiovascular death was lower in the highly increased Δ%BF group (HR 0.20 [0.08–0.48]), compared to those in the decreased Δ%BF group after adjustment for all covariates including physical activities and the changes in muscle mass. The risk of all-cause death and cardiovascular death linearly decreased with increasing Δ%BF (HR 0.72 [0.67–0.77] and 0.70 [0.60–0.82], respectively).
Conclusion
The increase in body fat is associated with a lower risk of all-cause death and cardiovascular death in a middle-age general population, independently with physical activities and the changes in muscle mass.
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Affiliation(s)
- Y Lee
- Hanyang University Kuri Hospital, Department of cardiology, Guri, Korea (Republic of)
| | - H C Park
- Hanyang University Kuri Hospital, Department of cardiology, Guri, Korea (Republic of)
| | - J H Shin
- Hanyang University Kuri Hospital, Department of cardiology, Guri, Korea (Republic of)
| | - Y H Lim
- Hanyang University, Division of Cardiology, Department of internal medicine, Seoul, Korea (Republic of)
| | - J K Park
- Hanyang University, Division of Cardiology, Department of internal medicine, Seoul, Korea (Republic of)
| | - J Shin
- Hanyang University, Division of Cardiology, Department of internal medicine, Seoul, Korea (Republic of)
| | - K S Kim
- Hanyang University, Division of Cardiology, Department of internal medicine, Seoul, Korea (Republic of)
| | - B K Kim
- Sung Ae Hospital, Department of Cardiology, Seoul, Korea (Republic of)
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Abstract
Abstract
Purpose
Patients with diabetes mellitus have an elevated risk of atrial fibrillation (AF). However, whether insulin resistance may elevate risk of AF incidence in non-diabetic is inconsistent. The aim of our study was to verify the association between insulin resistance and incidence of AF in non-diabetics.
Methods
We evaluated population-based cohorts embedded in the Korean Genome Epidemiology Study. Insulin resistance was expressed as Homeostasis Model Assessment for Insulin resistance (HOMA-IR). Baseline data including HOMA-IR and electrocardiography (ECG) were obtained at 2001. Subsequent biennial ECG was performed for identification of AF until 2016.
Results
Among the 8220 participants (46.8% male; median age 49 years), 25 participants had AF (0.3%) at baseline and 101 participants developed AF (1.2%) during follow up of 12 years. In multivariate Cox regression analysis, high HOMA-IR (≥1.4) was significantly associated with incident AF compared with low HOMA-IR (<1.40) (adjusted hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.3–3.0). In subgroup analysis, these association was consistent regardless of obesity (BMI<25; adjust HR 1.8, 95% CI 1.1–3.0, BMI≥25; adjust HR 2.3, 95% CI 1.3–4.0)
Subgroup analysis
Conclusion
Based on prospective cohort study, insulin resistance (HOMA-IR) was associated with AF independently of obesity in non-diabetics.
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Affiliation(s)
- J K Park
- Hanyang University, Seoul, Korea (Republic of)
| | - J H Park
- Hanyang University, Seoul, Korea (Republic of)
| | - Y G Lee
- Hanyang University Kuri Hospital, Cardiology, Guri, Korea (Republic of)
| | - J H Shin
- Hanyang University Kuri Hospital, Cardiology, Guri, Korea (Republic of)
| | - Y H Lim
- Hanyang University, Seoul, Korea (Republic of)
| | - R Heo
- Hanyang University, Seoul, Korea (Republic of)
| | - J Shin
- Hanyang University, Seoul, Korea (Republic of)
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Park JK, Choi YW, Kim BS, Chang KS, Lee YG, Shin JH, Lim YH, Park HC, Shin J. P1880Independent effect of physical activity and resting heart rate on incidence of atrial fibrillation in general population. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy565.p1880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J K Park
- Hanyang University, Seoul, Korea Republic of
| | - Y W Choi
- Hanyang University, Seoul, Korea Republic of
| | - B S Kim
- Hanyang University, Seoul, Korea Republic of
| | - K S Chang
- Hanyang University, Seoul, Korea Republic of
| | - Y G Lee
- Hanyang University Kuri Hospital, Cardiology, Guri, Korea Republic of
| | - J H Shin
- Hanyang University Kuri Hospital, Cardiology, Guri, Korea Republic of
| | - Y H Lim
- Hanyang University, Seoul, Korea Republic of
| | - H C Park
- Hanyang University Kuri Hospital, Cardiology, Guri, Korea Republic of
| | - J Shin
- Hanyang University, Seoul, Korea Republic of
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Lee Y, Park JK, Lim YH, Shin JH, Park HC, Shin J, Kim KS. 5047C-reactive protein and the risk of atrial fibrillation: KOGES 12 years' follow-up study. Eur Heart J 2018. [DOI: 10.1093/eurheartj/ehy566.5047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Y Lee
- Hanyang University, Seoul, Korea Republic of
| | - J K Park
- Hanyang University, Seoul, Korea Republic of
| | - Y H Lim
- Hanyang University, Seoul, Korea Republic of
| | - J H Shin
- Hanyang University, Seoul, Korea Republic of
| | - H C Park
- Hanyang University, Seoul, Korea Republic of
| | - J Shin
- Hanyang University, Seoul, Korea Republic of
| | - K S Kim
- Hanyang University, Seoul, Korea Republic of
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Yeo WL, Chew X, Smith DJ, Chan KP, Sun H, Zhao H, Lim YH, Ang EL. Probing the molecular determinants of fluorinase specificity. Chem Commun (Camb) 2018; 53:2559-2562. [PMID: 28184383 DOI: 10.1039/c6cc09213f] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular determinants of FlA1 fluorinase specificity were probed using 5'-chloro-5'-deoxyadenosine (5'-ClDA) analogs as substrates and FlA1 active site mutants. Modifications at F213 or A279 residues are beneficial towards these modified substrates, including 5'-chloro-5'-deoxy-2-ethynyladenosine, ClDEA (>10-fold activity improvement), and conferred novel activity towards substrates not readily accepted by wild-type FlA1.
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Affiliation(s)
- W L Yeo
- Metabolic Engineering Research Laboratory (MERL), Science and Engineering Institutes, Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos #01-01, Singapore 138669.
| | - X Chew
- Institute of Chemical and Engineering Sciences (ICES), A*STAR, 8 Biomedical Grove, Neuros #07-01/02/03, Singapore 138665.
| | - D J Smith
- Bioinformatics Institute, A*STAR, 30 Biopolis Street, Matrix #07-01, Singapore 138671 and Biotransformation Innovation Platform, A*STAR, 61 Biopolis Drive, Proteos #04-14, Singapore 138673
| | - K P Chan
- Institute of Chemical and Engineering Sciences (ICES), A*STAR, 8 Biomedical Grove, Neuros #07-01/02/03, Singapore 138665.
| | - H Sun
- Metabolic Engineering Research Laboratory (MERL), Science and Engineering Institutes, Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos #01-01, Singapore 138669.
| | - H Zhao
- Metabolic Engineering Research Laboratory (MERL), Science and Engineering Institutes, Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos #01-01, Singapore 138669. and 215 Roger Adams Laboratory, Box C3, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue Urbana, IL 61801, USA
| | - Y H Lim
- Institute of Chemical and Engineering Sciences (ICES), A*STAR, 8 Biomedical Grove, Neuros #07-01/02/03, Singapore 138665.
| | - E L Ang
- Metabolic Engineering Research Laboratory (MERL), Science and Engineering Institutes, Agency for Science, Technology and Research (A*STAR), 31 Biopolis Way, Nanos #01-01, Singapore 138669.
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Abstract
Background Injury is the commonest cause of morbidity and mortality amongst the younger age groups. Management of injuries has been identified as one of the major health issues facing our community. The study objective was to define the epidemiology of injury related deaths in Singapore. Methods A nationwide review of all deaths arising as a result of injury in 1995 was conducted. Results There were 913 cases with an injury mortality rate of 27 per 100,000 population. Ninety-seven percent (97%) were due to blunt injury. Falls from heights from deliberate self-harm was the commonest mechanism, followed by motor vehicle collisions (MVC). Fifty-two percent (52%) of MVC deaths were motorcyclists or pillion riders. Sixty-six percent (66%) of all deaths occurred in the prehospital phase. Central nervous system injury was the main cause of hospital deaths. Conclusion Results from this study will help our community focus on the appropriate preventive strategies to reduce mortality and the cost of injuries to our society.
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Affiliation(s)
- MKF Leong
- Singapore General Hospital, Department of Emergency Medicine, Outram Road, S169608, Singapore
| | - S Mujumdar
- Singapore General Hospital, Department of Emergency Medicine, Outram Road, S169608, Singapore
| | - L Raman
- Singapore General Hospital, Department of Emergency Medicine, Outram Road, S169608, Singapore
| | - YH Lim
- Singapore General Hospital, Department of Emergency Medicine, Outram Road, S169608, Singapore
| | - TC Chao
- Institute of Forensic Medicine
| | - V Anantharaman
- Singapore General Hospital, Department of Emergency Medicine, Outram Road, S169608, Singapore
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Lim YH, Hendricks J. A Case of Nonfatal Non-Collapsed Patient with Extreme Hyperkalaemia. HONG KONG J EMERG ME 2017. [DOI: 10.1177/102490790701400407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
This is a report of a non-collapsed patient with nonfatal, extreme hyperkalaemia of 10.7 mmol/L. The patient's hyperkalaemia was initially treated in the Emergency Department and then transferred to the Department of Renal Medicine of another hospital for further stabilisation. There have only been a few reported cases of successful management of extreme hyperkalaemia in excess of 10.0 mmol/L.
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Lim YH, Yeo A, Koh MP, Wong CY. Severely Injured Patients Presenting to the Singapore General Hospital: a one Year Study. HONG KONG J EMERG ME 2017. [DOI: 10.1177/102490790301000104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Study objectives To determine the quantity and resource utilisation in management of the severely injured patients presenting at the Singapore General Hospital (SGH). Method All patients who were initially triaged to the hospital Emergency Department's (ED) resuscitation room and all trauma related mortality in the year 1998 were studied. All records were traced and the cases were followed up. Important outcomes studied were mortality and length of hospital stay. Results Three hundred and forty-seven (0.2%) severely injured patients who were initially treated at the ED's resuscitation room were studied. The median age of the patients was 32 years old. Male patients formed 82.1% of the total. The three main causes of trauma in such patients were fall from height, motor vehicle related accidents and penetrating injuries caused by sharp instruments and firearms. Of all the patients, 62.8% were admitted to the ED between 1601 hours to 0759 hours and 30.5% of all severely injured patients were treated at the ED on weekends. One hundred and twenty three (35.4%) patients had emergency surgery within 24 hours of admission to the ED and 42.4% of the patients had an ISS score of 16 or more; 22.8% of patients had ISS score of 25 or more. The mortality of patients with ISS score of 25 or more was 39.2%. Conclusion One percent of all new ED patients with trauma were classified as ‘severely’ injured and these occurred mostly outside “normal working hours”. There was significant mortality in patients with ISS score of 25 or more.
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Affiliation(s)
| | - A Yeo
- Singapore General Hospital, Department of General Surgery and Trauma Service
| | - MP Koh
- Singapore General Hospital, Department of General Surgery
| | - CY Wong
- Singapore General Hospital, Department of General Surgery
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12
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Lim YH, Anantharaman V. Patients who Self-Discharge from the Emergency Department: a Three-Month Telephone Survey. HONG KONG J EMERG ME 2017. [DOI: 10.1177/102490790401100105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Study objectives To determine the main causes and outcomes of patients who self-discharged from the Emergency Department (ED). Methods Records of all patients who self-discharged from the ED of a tertiary level hospital were traced and telephone interviews were conducted. The duration of the study was from 15 July 2002 to 14 October 2002. Results There were 28,898 new attendances during the period of study and of these, 450 (1.6%) patients signed the self-discharge form. Of the 357 patients recruited into the study, the majority signed the self-discharge form because of refusal of admission to inpatient units (52.1%) or the ED observation ward (43.4%) for further treatment. One hundred and thirteen (31.7%) patients acknowledged that they were unwell during the interview and 85 (23.8%) patients sought some form of medical attention after leaving the ED. Conclusion Most of the patients who self-discharged from the ED were for personal reasons and very few were due to financial reasons.
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Affiliation(s)
- YH Lim
- Singapore General Hospital, Department of Emergency Medicine, Singapore 169608
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13
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Abstract
This is a rare case of sagittal sinus thrombosis occurring in the first trimester of pregnancy. A literature review was performed.
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14
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Ovejero D, Lim YH, Boyce AM, Gafni RI, McCarthy E, Nguyen TA, Eichenfield LF, DeKlotz CMC, Guthrie LC, Tosi LL, Thornton PS, Choate KA, Collins MT. Cutaneous skeletal hypophosphatemia syndrome: clinical spectrum, natural history, and treatment. Osteoporos Int 2016; 27:3615-3626. [PMID: 27497815 PMCID: PMC6908308 DOI: 10.1007/s00198-016-3702-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 07/06/2016] [Indexed: 12/01/2022]
Abstract
UNLABELLED Cutaneous skeletal hypophosphatemia syndrome (CSHS), caused by somatic RAS mutations, features excess fibroblast growth factor-23 (FGF23) and skeletal dysplasia. Records from 56 individuals were reviewed and demonstrated fractures, scoliosis, and non-congenital hypophosphatemia that in some cases were resolved. Phosphate and calcitriol, but not skin lesion removal, were effective at controlling hypophosphatemia. No skeletal malignancies were found. PURPOSE CSHS is a disorder defined by the association of epidermal and/or melanocytic nevi, a mosaic skeletal dysplasia, and an FGF23-mediated hypophosphatemia. To date, somatic RAS mutations have been identified in all patients whose affected tissue has undergone DNA sequencing. However, the clinical spectrum and treatment are poorly defined in CSHS. The purpose of this study is to determine the spectrum of the phenotype, natural history of the disease, and response to treatment of hypophosphatemia. METHODS Five CSHS subjects underwent prospective data collection at clinical research centers. A review of the literature identified 45 reports that included a total of 51 additional patients, in whom the findings were compatible with CSHS. Data on nevi subtypes, bone histology, mineral and skeletal disorders, abnormalities in other tissues, and response to treatment of hypophosphatemia were analyzed. RESULTS Fractures, limb deformities, and scoliosis affected most CSHS subjects. Hypophosphatemia was not present at birth. Histology revealed severe osteomalacia but no other abnormalities. Skeletal dysplasia was reported in all anatomical compartments, though less frequently in the spine; there was no clear correlation between the location of nevi and the skeletal lesions. Phosphate and calcitriol supplementation was the most effective therapy for rickets. Convincing data that nevi removal improved blood phosphate levels was lacking. An age-dependent improvement in mineral abnormalities was observed. A spectrum of extra-osseous/extra-cutaneous manifestations that included both benign and malignant neoplasms was present in many subjects, though osteosarcoma remains unreported. CONCLUSION An understanding of the spectrum, natural history, and efficacy of treatment of hypophosphatemia in CSHS may improve the care of these patients.
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Affiliation(s)
- D Ovejero
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National ADDRESSES, references BRACKETS, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive, Room 228, MSC 4320, Bethesda, MD, 20892-4320, USA
- Departament de Medicina, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Y H Lim
- Department of Dermatology, Yale University School of Medicine, New Haven, CT, USA
| | - A M Boyce
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National ADDRESSES, references BRACKETS, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive, Room 228, MSC 4320, Bethesda, MD, 20892-4320, USA
| | - R I Gafni
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National ADDRESSES, references BRACKETS, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive, Room 228, MSC 4320, Bethesda, MD, 20892-4320, USA
| | - E McCarthy
- Department of Pathology, The Johns Hopkins University, Baltimore, MD, USA
| | - T A Nguyen
- Albert Einstein College of Medicine, Bronx, NY, USA
- Departments of Dermatology and Pediatrics, San Diego and Rady Children's Hospital, University of California, San Diego, CA, USA
| | - L F Eichenfield
- Departments of Dermatology and Pediatrics, San Diego and Rady Children's Hospital, University of California, San Diego, CA, USA
| | - C M C DeKlotz
- Division Dermatology, Department of Medicine and Department of Pediatrics, Georgetown University Medical Center, Washington, DC, USA
| | - L C Guthrie
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National ADDRESSES, references BRACKETS, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive, Room 228, MSC 4320, Bethesda, MD, 20892-4320, USA
| | - L L Tosi
- Bone Health Program, Division of Orthopaedics and Sports Medicine, Children's National Health System, Washington, DC, USA
| | - P S Thornton
- Department of Endocrinology and Diabetes, Cook Children Medical Center, Fort Worth, TX, USA
| | - K A Choate
- Department of Dermatology, Yale University School of Medicine, New Haven, CT, USA
| | - M T Collins
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Disease Branch, National ADDRESSES, references BRACKETS, National Institute of Dental and Craniofacial Research, National Institutes of Health, 30 Convent Drive, Room 228, MSC 4320, Bethesda, MD, 20892-4320, USA.
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Kim BK, Lee YG, Lim YH, Kim KS, Shin JH. Comparison of cardiovascular mortality between patients with sustained normotension, white coat hypertension, masked hypertension and sustained hypertension in a clinical cohort. Eur Heart J 2013. [DOI: 10.1093/eurheartj/eht310.p5650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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16
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Gilbert EA, Lim YH, Vickaryous MK, Armstrong CL. Heterochronic protein expression patterns in the developing embryonic chick cerebellum. Anat Rec (Hoboken) 2012; 295:1669-82. [PMID: 22865685 DOI: 10.1002/ar.22544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 06/12/2012] [Accepted: 07/11/2012] [Indexed: 12/18/2022]
Abstract
The advantages of the embryonic chick as a model for studying neural development range from the relatively low cost of fertilized eggs to the rapid rate of development. We investigated in ovo cerebellar development in the chick, which has a nearly identical embryonic period as the mouse (19-22 days). We focused on three antigens: Calbindin (CB), Zebrin II (ZII), and Calretinin (CR), and our results demonstrate asynchronous expression patterns during cerebellar development. Presumptive CB+ Purkinje cells are first observed at embryonic day (E)10 in clusters in posterior cerebellum. At E12, corresponding with global expression of CB across the cerebellum, Purkinje cells began to express ZII. By E14-E16, Purkinje cells disperse into a monolayer and develop a pattern of alternating immunopositive and immunonegative ZII stripes. CR is initially expressed by clusters of presumptive Purkinje cells in the nodular zone at E8. However, this expression is transient and at later stages, CR is largely confined to the granule and molecular layers. Before hatch (E18-E20), Purkinje cells adopt a morphologically mature phenotype with complex dendritic arborizations. Comparing this data to that seen in mice, we found that the sequence of Purkinje cell formation, protein expression, and development is similar in both species, but these events consistently begin ∼5-7 days earlier in the precocial chick cerebellum, suggesting an important role for heterochrony in neurodevelopment.
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Affiliation(s)
- E A Gilbert
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, 50 Stone Road, Guelph, Ontario, Canada
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17
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Lim BC, Ki CS, Cho A, Hwang H, Kim KJ, Hwang YS, Kim YE, Yun JY, Jeon BS, Lim YH, Paek SH, Chae JH. Pantothenate kinase-associated neurodegeneration in Korea: recurrent R440P mutation in PANK2 and outcome of deep brain stimulation. Eur J Neurol 2011; 19:556-61. [PMID: 22103354 DOI: 10.1111/j.1468-1331.2011.03589.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND AND PURPOSE The purpose of this study was to evaluate the mutation status of PANK2 among Korean patients with pantothenate kinase-associated neurodegeneration (PKAN) and to document the outcome of pallidal deep brain stimulation (DBS). METHODS Direct sequencing and deletion/duplication analysis of PANK2 were conducted in 12 patients (11 unrelated) with PKAN, diagnosed on the basis of extrapyramidal dysfunction and the 'eye-of-the-tiger sign' on brain magnetic resonance imaging (MRI). Pallidal DBS was conducted in four patients, and the outcomes were measured using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). RESULTS A PANK2 mutation was identified in both alleles in all patients. The most prevalent mutation was c.1319G>C (p.R440P) in 8/22 mutated alleles (36%). An intragenic deletion ranging from exons 2 to 4 was found in one allele (1/22, 4.5%) using deletion/duplication analysis. The outcome of pallidal DBS was favorable in two patients with atypical PKAN and moderate severity of dystonia. However, two patients with typical PKAN and relatively severe symptoms showed variable responses. CONCLUSIONS The c.1319G>C (p.R440P) mutation appears to be a founder genotype among Korean patients with PKAN. Furthermore, this study provides additional data for the recent international effort to evaluate the efficacy of pallidal DBS in the treatment of patients with PKAN.
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Affiliation(s)
- B C Lim
- Department of Pediatrics, Seoul National University College of Medicine, Seoul National University Children's Hospital, Seoul, Korea.
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18
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Lim YH, Relus Kek YL, Lim PY, Yap HM, Vivien Goh TL, Ng LC. Environmental surveillance and molecular characterization of Legionella in tropical Singapore. Trop Biomed 2011; 28:149-159. [PMID: 21602781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Legionnaires' disease is often acquired by inhalation of legionellae from a contaminated environmental source. In recent years, Singapore has seen an increase in the use of aerosol-generating fixtures such as mist fans and spa pools. Poorly maintained and designed water fixtures could pose a public health threat to the community. In this study, we provided an update on the prevalence of Legionella in mist fans (N=28), household water heaters with storage tanks (N=19) and instantaneous heaters (N=30); and extended the survey to spa pools (N=29) and aerosol-generating fixtures in nursing homes (N=116). The prevalence of Legionella were 21.1% in water heaters with storage tanks, 24.1% in spa pools, 14.2% in mist fans and 3.3% in instantaneous heaters. Legionella was not detected in nursing homes. A total of 37 isolates were subjected to molecular characterization using Sequence-Based Typing (SBT) protocol from the European Working Group on Legionella Infections (EWGLI). This is the first study on the use of SBT protocol on environmental strains isolated from tropical South East Asia. The Legionella flora was very heterogenous. The overall diversity of the allelic profile was found to be 0.970 (95% CI 0.946 - 0.994). All known STs of our isolates have been associated with clinical cases in EWGLI database. The phylogenetic analysis showed that our novel environmental isolates were clustered with clinical STs that were previously reported in Europe, Japan, United Kingdom and United States etc. (in EWGLI database), suggesting that Legionella found in the environment of Singapore may potentially cause human disease.
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Affiliation(s)
- Y H Lim
- Environmental Health Institute, National Environment Agency, Singapore, 11 Biopolis Way #06-05/08 Helios Block Singapore 138667
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Abstract
BACKGROUND Anesthetic titration using spectral entropy monitoring reduces anesthetic requirements and shortens recovery in adult surgical patients. This study was performed to evaluate the effect of entropy monitoring on end-tidal sevoflurane concentration and recovery characteristics in pediatric patients undergoing sevoflurane anesthesia. METHODS Seventy-eight children (aged 3-12 years) scheduled for a tonsillectomy and/or an adenoidectomy were randomly divided into one of two groups: standard practice (Standard) or entropy-guided (Entropy). In the Standard group, sevoflurane was adjusted to maintain the heart rate and systolic blood pressure (BP) within 20% of the baseline values. In the Entropy group, sevoflurane was adjusted to achieve a state entropy of 40-50. We compared the entropy values, end-tidal sevoflurane concentration and recovery times between groups. RESULTS During maintenance of anesthesia, the entropy and BP values were higher in the Entropy group (P<0.05). The end-tidal sevoflurane concentration during maintenance was lower in the Entropy group (2.2 (0.3) vol%) compared with the Standard group (2.6 (0.4) vol%) (P<0.05). Recovery times were faster in the Entropy group (P<0.05). CONCLUSIONS Compared with standard practice, we found that entropy-guided anesthetic administration was associated with a reduced sevoflurane concentration and a slightly faster emergence and recovery in 3-12-year-old children.
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Affiliation(s)
- S R Choi
- Department of Anesthesiology and Pain Medicine, Dong-A University Hospital, Busan, South Korea
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Saw JT, Bahari MB, Ang HH, Lim YH. Herbal use amongst multiethnic medical patients in Penang Hospital: pattern and perceptions. Med J Malaysia 2006; 61:422-32. [PMID: 17243519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A cross sectional survey on pattern and perception of herbal use among medical patients in Penang Hospital was conducted. Among 250 patients surveyed, 67.9% were using herbal medicine and conventional medicine concomitantly. A majority of the patients used herbs for health maintenance (51.3%) purpose. More than 90% of herbal users did not disclose herbal use to their physician and "Doctor never asked" was the major reason given (54.2%). The Chinese reported the highest rate of herbal use but was least likely to disclose. These findings are important for health professionals to ensure medication safety and recognise potential drug herb interaction.
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Affiliation(s)
- J T Saw
- School of Pharmacy, University College Sedaya International, No 1, Jalan Menara Goding, UCSI Heights, 56000 Kuala Lumpur, Malaysia
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Chung IM, Ali M, Hahn SJ, Siddiqui NA, Lim YH, Ahmad A. Chemical Constituents from the Hulls of Oryza sativa with Cytotoxic Activity. Chem Nat Compd 2005. [DOI: 10.1007/s10600-005-0108-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Kyung SY, Kim YJ, Lim YH, An CH, Lee SP, Park JW, Jung SH. Spontaneous Resolution of Residual Pleural Thickening in Tuberculous Pleurisy. Tuberc Respir Dis (Seoul) 2005. [DOI: 10.4046/trd.2005.59.1.69] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- S. Y. Kyung
- Division of Pulmonology, Department of Internal Medicine, Gil Medical Center, Gachon Medical School, Incheon, Korea
| | - Y. J. Kim
- Division of Pulmonology, Department of Internal Medicine, Gil Medical Center, Gachon Medical School, Incheon, Korea
| | - Y. H. Lim
- Division of Pulmonology, Department of Internal Medicine, Gil Medical Center, Gachon Medical School, Incheon, Korea
| | - C. H. An
- Division of Pulmonology, Department of Internal Medicine, Gil Medical Center, Gachon Medical School, Incheon, Korea
| | - S. P. Lee
- Division of Pulmonology, Department of Internal Medicine, Gil Medical Center, Gachon Medical School, Incheon, Korea
| | - J. W. Park
- Division of Pulmonology, Department of Internal Medicine, Gil Medical Center, Gachon Medical School, Incheon, Korea
| | - S. H. Jung
- Division of Pulmonology, Department of Internal Medicine, Gil Medical Center, Gachon Medical School, Incheon, Korea
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Abstract
At least 11 HLA-DRB1*12 alleles have been identified to date. We report a new HLA-DRB1*12 allele, DRB1*1210, that was identified in the Korean population. This new allele differs from HLA-DRB1*120101 by a single nucleotide at position 40 (G-->A) in exon 1 that falls within codon--16 (GTT-->ATT). This change results in a single valine to isoleucine amino acid alteration.
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Affiliation(s)
- E Kim
- National Genome Research Institute, National Institute of Health, Eunpyung-gu, Seoul, South Korea
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Abstract
We examined the combined effects of gamma-radiation (24 degrees C) on spores of Clostridium botulinum-type Eklund strain suspended in different gas-saturated Na-phosphate buffer in absence or presence of protectors or sensitizers. Response surface methodology (RSM) was also used to ascertain the effects of radiation on the recovery of spores using a medium containing various levels of NaCl or Na-thioglycollate. The former (< 0.5%) decreased viable spore counts, but the latter (0.15%) did not. Irradiation inactivation of Eklund spores was most effective in air-saturated buffers compared to N2O and N2 gas. The Na2-EDTA (0.01 M) was the most efficient radioprotector of spores due to its reactivity toward hydroxy radicals, followed by t-butanol (0.1 M) in NO2 or N(2)-saturated buffers, respectively. Catalase (10.0 mg ml(-1)) and DL-cysteine (0.1 mM) sensitized the spores during irradiated N2O or N(2)-saturated buffers, and NaCl (0.01 M) only sensitized spores in N2 environment. Spores frozen at -75 degrees C for 30 days and thawed prior to use were more sensitive to radiation damage compared to freshly prepared spores. Glycerol (15%), in Na-phosphate buffer (pH 7.0, 0.06 M), protected Eklund spores and increased the number of spores from 10(6) to 10(11) colony forming unit (CFU) ml(-1), and enhanced their radiosensitivities. Seven strains of C. botulinum type E were screened for plasmids and strain BL764 had two plasmids (15.8 and 46.8 mDa), BL4028 also had two (4.4 and 13.2 mDa), BL4850 contained only one (4.9 mDa), whereas EQA, BL211, Eklund, and Beluga had none. Gamma-Radiation (10 kGy, absorbed dose) cured the 15.8-mDa plasmid in strain BL764, but its absence yielded no changes in toxigenicity.
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Affiliation(s)
- Y H Lim
- Department of Food Science and Technology, University of Georgia, Athens, GA 30602, USA
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Abstract
[reaction: see text] Photocycloaddition of 2-pyridones yields a rigid polycyclic product containing a 1,5-cyclooctadiene. The cis isomer, with the alkenes in close proximity, undergoes a transannular reaction when treated with chlorine to give a polyquinane product. The chlorination reaction involves migration of an amide nitrogen and forms a single isomer, generating eight stereogenic centers in two steps.
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Affiliation(s)
- T A Ader
- Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400
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Yoon HG, Kim HY, Lim YH, Kim HK, Shin DH, Hong BS, Cho HY. Identification of essential amino acid residues for catalytic activity and thermostability of novel chitosanase by site-directed mutagenesis. Appl Microbiol Biotechnol 2001; 56:173-80. [PMID: 11499927 DOI: 10.1007/s002530000571] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The functional importance of a conserved region in a novel chitosanase from Bacillus sp. CK4 was investigated. Each of the three carboxylic amino acid residues (Glu-50, Glu-62, and Asp-66) was changed to Asp and Gln or Asn and Glu by site-directed mutagenesis, respectively. The Asp-66-->Asn and Asp-66-->Glu mutation remarkably decreased kinetic parameters such as Vmax and kcat to approximately 1/1,000 those of the wild-type enzyme, indicating that the Asp-66 residue was essential for catalysis. The thermostable chitosanase contains three Cys residues at positions 49, 72, and 211. The Cys-49-->Ser/Tyr and Cys-72-->Ser/Tyr mutant enzymes were as stable to thermal inactivation and denaturating agents as the wild-type enzyme. However, the half-life of the Cys-211-->Ser/Tyr mutant enzyme was less than 10 min at 80 degrees C, while that of the wild-type enzyme was about 90 min. Moreover, the residual activity of Cys-211-->Ser/Tyr enzyme was substantially decreased by 8 M urea; and it lost all catalytic activity in 40% ethanol. These results show that the substitution of Cys with any amino acid residues at position 211 seems to affect the conformational stability of the chitosanase.
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Affiliation(s)
- H G Yoon
- Department of Food and Biotechnology, Graduate School of Biotechnology, Korea University, Seoul
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Hoag KA, Clise-Dwyer K, Lim YH, Nashold FE, Gestwicki J, Cancro MP, Hayes CE. A quantitative-trait locus controlling peripheral B-cell deficiency maps to mouse Chromosome 15. Immunogenetics 2000; 51:924-9. [PMID: 11003386 DOI: 10.1007/s002510000223] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Peripheral B-lymphocyte homeostasis is determined through incompletely defined positive and negative regulatory processes. The A/WySnJ mouse, but not the related A/J strain, has disturbed homeostasis leading to peripheral B-lymphocyte deficiency. B lymphopoeisis is normal in A/WySnJ mice, but the B cells apoptose rapidly in the periphery. This B cell-intrinsic defect segregated as a single locus, Bcmd, in (A/WySnJxA/J)F2 mice. Here we mapped a quantitative-trait locus (QTL) that contributes to the A/WySnJ B-cell deficiency by examining the F2 progeny of a cross between strains A/WySnJ and CAST/Ei. In this cross, minimally 1.9 QTLs controlling peripheral B lymphocyte deficiency segregated. The (A/WySnJxCAST/Ei)F2 mice were phenotyped for splenic B-cell percentage and the DNA from progeny with extreme phenotypes was used to map the QTL by the simple-sequence length polymorphism method. A genome scan showed linkage between peripheral B-cell deficiency and Chromosome (Chr) 15 markers. When closely spaced Chr 15 markers were analyzed, the 99% confidence interval for the QTL map position extended along the entire chromosome length. The peak lod scores >17 occurred between 30 and 45 cM. We conclude that a significant QTL segregating in (A/WySnJxCAST/Ei)F2 mice resides in this middle region of Chr 15.
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Affiliation(s)
- K A Hoag
- Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, 53706, USA
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Yoon HG, Kim HY, Lim YH, Kim HK, Shin DH, Hong BS, Cho HY. Thermostable chitosanase from Bacillus sp. Strain CK4: cloning and expression of the gene and characterization of the enzyme. Appl Environ Microbiol 2000; 66:3727-34. [PMID: 10966383 PMCID: PMC92213 DOI: 10.1128/aem.66.9.3727-3734.2000] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A thermostable chitosanase gene from the environmental isolate Bacillus sp. strain CK4, which was identified on the basis of phylogenetic analysis of the 16S rRNA gene sequence and phenotypic analysis, was cloned, and its complete DNA sequence was determined. The thermostable chitosanase gene was composed of an 822-bp open reading frame which encodes a protein of 242 amino acids and a signal peptide corresponding to a 30-kDa enzyme. The deduced amino acid sequence of the chitosanase from Bacillus sp. strain CK4 exhibits 76.6, 15.3, and 14.2% similarities to those from Bacillus subtilis, Bacillus ehemensis, and Bacillus circulans, respectively. C-terminal homology analysis shows that Bacillus sp. strain CK4 belongs to cluster III with B. subtilis. The gene was similar in size to that of the mesophile B. subtilis but showed a higher preference for codons ending in G or C. The enzyme contains 2 additional cysteine residues at positions 49 and 211. The recombinant chitosanase has been purified to homogeneity by using only two steps with column chromatography. The half-life of the enzyme was 90 min at 80 degrees C, which indicates its usefulness for industrial applications. The enzyme had a useful reactivity and a high specific activity for producing functional oligosaccharides as well, with trimers through hexamers as the major products.
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Affiliation(s)
- H G Yoon
- Graduate School of Biotechnology, Korea University, Seoul 136-701, Korea
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Kim DJ, Oh DJ, Kim B, Lim YH, Kang WH, Lee BH, Lee SK, Huh W, Kim SE, Lee MK, Kang SA, Oh HY. The effect of continuous ambulatory peritoneal dialysis on change in serum leptin. Perit Dial Int 1999; 19 Suppl 2:S172-5. [PMID: 10406513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
OBJECTIVE Elevated serum leptin can contribute to anorexia and poor nutrition in patients with chronic renal failure, because leptin is elevated in chronic renal failure patients with or without dialysis, especially in chronic ambulatory peritoneal dialysis (CAPD) patients. The aim of this study was to find whether leptin can be removed by peritoneal dialysis (PD) and to analyze factors that can affect serum leptin after start of CAPD by observing the change in serum leptin shortly after start of CAPD and its correlation with body mass index (BMI), with serum insulin, and with residual renal function. DESIGN Twenty patients who started CAPD during the observation period were studied. Serum leptin was measured by radioimmunoassay before start of CAPD, 3-5 days after start of CAPD, and 1 month and 3 months after start of CAPD. Simultaneously, body weight, serum insulin, and residual renal function were measured. To compensate for the circardian rhythm of leptin, removal of leptin was assessed by measuring dialysate leptin divided by average serum leptin before and after a peritoneal equilibration test (PET). RESULTS Leptin was eliminated by PD with a dialysate-to-serum ratio of 0.16+/-0.07, which was comparable to removal of beta2-microglobulin (0.14+/-0.06). The mean serum leptin concentrations did not decrease after 3-5 days of CAPD (8.4+/-13.1 ng/mL-->11.9+/-18.0 ng/mL) despite its removal by PD, and levels increased markedly to 189% of basal serum leptin 1 month after start of PD and to 260% of basal serum leptin 3 months after start of PD. Correlation coefficients (Spearman's rho) between change of serum leptin and change of BMI, of serum insulin, of glomerular filtration rate (average of urine creatinine clearance and urine urea clearance) were 0.267 (p > 0.05, n = 20), 0.441 (p > 0.05, n = 16), 0.706 (p > 0.05, n = 8) respectively. CONCLUSION Leptin is removed by peritoneal dialysis. Serum leptin did not decrease in 5 days after the start of PD despite its removal by PD, but increased markedly thereafter, within 3 months after start of PD. We could not find a significant correlation between the change in leptin and the change in BMI. Factors other than fat-mass gain can stimulate leptin increase shortly after start of PD.
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Affiliation(s)
- D J Kim
- Department of Medicine, College of Medicine, Sung Kyun Kwan University, Seoul, Korea
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Lim YH, Leem MJ, Shin DH, Chang HB, Hong SW, Moon EY, Lee DK, Yoon SJ, Woo WS. Cytotoxic constituents from the roots of Anthriscus sylvestris. Arch Pharm Res 1999; 22:208-12. [PMID: 10230514 DOI: 10.1007/bf02976548] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Activity-guided fractionation of the roots of Anthriscus sylvestris resulted in the isolation and characterization of five cytotoxic compounds, deoxypodophyllotoxin (1), falcarindiol (2), and angeloyl podophyllotoxin (5) from the hexane soluble fraction and morelensin (3), bursehernin (4) from the chloroform soluble fraction. It is the first report of the occurrence of compound 5 in nature.
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Affiliation(s)
- Y H Lim
- R&D Centre, Dong-wha Pharmaceutical Ind. Co., Ltd, Anyang City, Korea
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31
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Lim YH, Anantharaman V. Hospital resuscitation of cardiac arrest patients. Singapore Med J 1999; 40:165-70. [PMID: 10402896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Resuscitation of collapsed cardiac patients is often a not-too-successful affair. It has been repeatedly emphasised that the most important aspect of cardiac resuscitation is early access, early recognition of ventricular fibrillation and early defibrillation in patients with ventricular fibrillation. However, the co-ordination of the various phases of cardiac resuscitation itself, which is often forgotten, would need a good organisation so that a systematic assessment of the patient can be done while resuscitation is in progress. In this report, we describe a case of successful prolonged cardiac resuscitation with emphasis on the organisation of resuscitation as well as early defibrillation. We would also like to emphasise that all procedures that were done were performed correctly and their effects on the monitored patient were assessed frequently so as to maximise efficiency, myocardial salvage and patient survival.
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Affiliation(s)
- Y H Lim
- Department of Emergency Medicine, Singapore General Hospital
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32
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Abstract
The enzyme responsible for conversion of all-trans-retinol into retinyl esters, the lecithin retinol acyltransferase (LRAT) has been characterized at the molecular level. The cDNA coding for this protein was cloned and its amino acid sequence deduced. LRAT is composed of a polypeptide of 230 amino acid residues with a calculated mass of 25.3 kDa. Tissue distribution analysis by Northern blot showed expression of a 5.0-kilobase transcript in the human retinal pigment epithelium as well as in other tissues that are known for their high LRAT activity and vitamin A processing. Affinity labeling experiments using specific compounds with high affinity for LRAT and monospecific polyclonal antibodies raised in rabbits against two peptide sequences for LRAT confirmed the molecular mass of LRAT as a 25-kDa protein. High performance liquid chromatography analysis of the reaction product formed by HEK-293 cells transfected with LRAT cDNA confirmed the ability of the transfected cells to convert [3H]all-trans-retinol into authentic [3H]all-trans-retinyl palmitate as chemically determined.
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Affiliation(s)
- A Ruiz
- Department of Neurobiology, School of Medicine, University of California, Los Angeles, California 90095, USA
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33
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Lim YH, Anantharaman V. Pseudo myocardial infarct--electrocardiographic pattern in a patient with diabetic ketoacidosis. Singapore Med J 1998; 39:504-6. [PMID: 10067388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Diabetic ketoacidosis is an extremely serious complication of diabetes mellitus. It arises because of a complex disturbance in glucose metabolism. There is usually a precipitating cause such as sepsis or myocardial infarction. If not recognised and appropriately treated, it can have devastating consequences. This is a case report of a patient with severe diabetic ketoacidosis and interesting electrocardiographic findings. The initial electrocardiographic (ECG) findings were suggestive of an acute myocardial infarction. The ECG changes normalised remarkably following initial management of the diabetic ketoacidosis. There have been only occasional reports of hyperkalemia causing electrocardiographic changes, closely resembling those of acute myocardial infarction.
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Affiliation(s)
- Y H Lim
- Department of Emergency Medicine, Singapore General Hospital, Singapore
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34
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Yap KL, Lim YH, Tan SC. Rotavirus electropherotypes from the Kuala Lumpur Hospital: a re-examination after an interval of seven years. Malays J Pathol 1998; 20:25-30. [PMID: 10879260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The objective of this study was to ascertain the extent changes have occurred in the epidemiology of human rotavirus electropherotypes from the same location 7 to 8 years after an earlier study. Genomic RNA profiles of rotaviruses from diarrhoeic children admitted to the Kuala Lumpur Hospital from April to December 1996 were determined by polyacrylamide gel electrophoresis and silver staining. A total of 179 group A rotaviruses were detected from 870 children: 175 with legible staining of all RNA segments were classified into 14 distinct electropherotypes (10 and 4 with long and short migration patterns respectively). In addition, the results revealed: high predominance of long pattern electropherotypes (94% of the total electropherotypes); most long electropherotypes with RNA profiles which all 11 RNAs migrated separately (8 of 10 electropherotypes); all short electropherotypes had segments 2 and 3 that co-migrated; presence of a very numerically dominant electropherotype (75% of all electropherotypes); frequent co-circulation of the dominant electropherotype-present throughout the study period--with other electropherotypes present for limited periods; sequential temporal appearances by similar electropherotypes. These observations were similar to that of an earlier study conducted in 1988/89. Nevertheless, the dominant electropherotype in the present study was different and not among the electropherotypes detected in the earlier study.
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Affiliation(s)
- K L Yap
- Department of Biomedical Sciences, Faculty of Allied Health Sciences, Universiti Kebangsaan Malaysia
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35
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Lim YH, Yoshimura T, Kurokawa Y, Esaki N, Soda K. Nonstereospecific transamination catalyzed by pyridoxal phosphate-dependent amino acid racemases of broad substrate specificity. J Biol Chem 1998; 273:4001-5. [PMID: 9461589 DOI: 10.1074/jbc.273.7.4001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Pyridoxal 5'-phosphate-dependent amino acid racemases of broad substrate specificity catalyze transamination as a side reaction. We studied the stereospecificities for hydrogen abstraction from C-4' of the bound pyridoxamine 5'-phosphate during transamination from pyridoxamine 5'-phosphate to pyruvate catalyzed by three amino acid racemases of broad substrate specificity. When the enzymes were incubated with (4'S)- or (4'R)-[4'-3H]pyridoxamine 5'-phosphate in the presence of pyruvate, tritium was released into the solvent from both pyridoxamine 5'-phosphates. Thus, these enzymes abstract a hydrogen nonstereospecifically from C-4' of the coenzyme in contrast to the other pyridoxal 5'-phosphate-dependent enzymes so far studied, which catalyze the stereospecific hydrogen removal. Amino acid racemase of broad substrate specificity from Pseudomonas putida produced D- and L-glutamate from alpha-ketoglutarate through the transamination with L-ornithine. Because glutamate does not serve as a substrate for racemization, the enzyme catalyzed the nonstereospecific overall transamination between L-ornithine and alpha-ketoglutarate. The cleavage and formation of the C-H bond at C-4' of the coenzyme and C-2 of the substrate thus occurs nonstereospecifically on both sides of the plane of the coenzyme-substrate complex intermediate. Amino acid racemase of broad substrate specificity is the first example of a pyridoxal enzyme catalyzing nonstereospecific transamination.
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Affiliation(s)
- Y H Lim
- Laboratory of Microbial Biochemistry, Institute for Chemical Research, Kyoto University, Uji, Kyoto 611, Japan
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36
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Abstract
A 40-year-old woman was admitted because of abdominal pain and diarrhea. She sometimes experienced paroxysmal hypertension, sweating, headache, and palpitation. Sigmoidoscopic findings showed well-demarcated diffuse mucosal edema, hyperemia, and easy touch bleeding from distal descending colon up to the splenic flexure area. Barium x-ray showed loss of haustral marking, thumb printing appearance, and diffuse luminal stenosis in the transverse, descending, and sigmoid colon. On the abdominal computed tomogram, a 3.8-cm sized well-enhanced right adrenal mass was incidentally found. Twenty-four hour urinary excretion of vanillyl mandelic acid, norepinephrine, and normetanephrine were increased. Iodine131 metaiodobenzylguanidine scan showed hot uptake on the right adrenal gland compatible with pheochromocytoma. Exploratory laparotomy was done under the impression of ischemic colitis associated with pheochromocytoma. Adrenalectomy and resection of the stenotic left colon were performed. After surgery, pain subsided, blood pressure fell gradually, blood sugar and catecholamine level became normal, and bowel habit returned to normal.
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Affiliation(s)
- C I Sohn
- Department of General Surgery, Samsung Medical Center, Seoul, Korea
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37
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Affiliation(s)
- Y H Choi
- College of Pharmacy, Seoul National University, Korea
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38
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Abstract
The correct 1H-NMR assignment of artemisinic acid was achieved through COSY, HETCOR, DEPT, J-resolved, and NOESY techniques. The present experiments supplemented by molecular mechanics calculations could correct some previously misinterpreted signals, notably of H-2s, H-3s, and H-6. The results should be helpful in further work with this important artemisinin-analogue precursor.
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Affiliation(s)
- S U Kim
- Department of Agricultural Chemistry and The Research Center for New Biomaterials in Agriculture, Seoul National University, Suwon 441-744, Korea
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39
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Gilbert BA, Lim YH, Ding J, Badwey JA, Rando RR. Farnesyl thiotriazole, a potent neutrophil agonist and structurally novel activator of protein kinase C. Biochemistry 1995; 34:3916-20. [PMID: 7696255 DOI: 10.1021/bi00012a007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Farnesylcysteine derivatives can initiate or inhibit superoxide (O2-) release in neutrophils. The mechanism by which one of these derivatives, farnesyl thiotriazole (FTT), initiates O2- release in neutrophils is the subject of this paper. Treatment of guinea pig neutrophils with FTT results in the rapid release of O2- by a route shown to be independent of the chemotactic peptide N-formyl-Met-Leu-Phe (fMLP) receptor. The signal transduction pathway utilized by the chemoattractant fMLP is generally accepted as the paradigm for receptor-mediated stimulation of O2- production. Antagonists of fMLP had no effect on FTT-induced O2- release, and pretreatment of neutrophils with fMLP had no effect on the ability of FTT to trigger further O2- generation. In fact, FTT behaves like a typical protein kinase C (PKC) activator. It promotes phosphorylation of the 47-kDa subunit of the NADH oxidase complex (p47-phox) in neutrophils, and this phosphorylation is specifically blocked by 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an antagonist of PKC. FTT is also shown to activate PKC in vitro in a specific and saturable fashion. FTT is approximately equipotent with (S)-diolein, a physiologically relevant activator of this kinase. FTT represents a new, and quite novel, structure for a PKC activator. PKC activators include diglycerides and the structurally diverse tumor promoters.
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Affiliation(s)
- B A Gilbert
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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40
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Park SH, Chae YA, Lee HJ, Lim YH, Kim SU. Production of (-)-7-Hydroxyisopiperitenone from (-)-Isopiperitenone by a Suspension Cell Culture of Mentha piperita. Planta Med 1994; 60:374-5. [PMID: 17236058 DOI: 10.1055/s-2006-959505] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- S H Park
- Department of Agricultural Chemistry and The Research Center for New Bio-Materials in Agriculture, Seoul National University, Suwon 441-744, Korea
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41
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Abstract
This study investigates whether there is any difference in the month of birth between people with schizophrenia and controls in Korea. When 1606 patients with schizophrenia were compared with 4582 age- and sex-matched controls, there was no statistically significant difference in the month of birth, the season of birth of schizophrenic patients was not related to sex, family history or handedness.
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Affiliation(s)
- C E Kim
- Yong-In Mental Hospital, Kyunggi-Do, Korea
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42
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Ma YT, Shi YQ, Lim YH, McGrail SH, Ware JA, Rando RR. Mechanistic studies on human platelet isoprenylated protein methyltransferase: farnesylcysteine analogs block platelet aggregation without inhibiting the methyltransferase. Biochemistry 1994; 33:5414-20. [PMID: 8180165 DOI: 10.1021/bi00184a009] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The kinetic mechanism of the human platelet S-adenosyl-L-methionine (AdoMet)-linked isoprenylated protein methyltransferase was studied and determined to be ordered bibi. AdoMet binds first, and S-adenosyl-L-homocysteine (AdoHcy) departs last. Simple N-acetylated farnesylated cysteine analogs, such as N-acetyl-S-farnesyl-L-cysteine (AFC), are excellent substrates for the enzyme. Although many N-acetylated farnesylated cysteine analogs are excellent substrates for the enzyme, analogs with bulky moieties adjacent to the farnesylcysteine are neither substrates nor inhibitors of the enzyme. Two molecules of this class, N-benzoyl-S-farnesyl-L-cysteine (BzFC) and N-pivaloyl-S-farnesyl-L-cysteine (PFC) are useful in sorting out the putative physiological role of the methyltransferase in mediating human platelet aggregation because their pharmacological activities are unlinked to methyltransferase inhibition. When studied as inhibitors of platelet aggregation, the analogs are as active, or more active, than bona fide methyltransferase inhibitors of similar structure. Therefore, although it is possible that methyltransferase inhibitors, such as AFC, inhibit the enzyme when applied to cells, the observed pharmacological effects appear to be unrelated to this blockade. The new FC analogs described here have revealed a new signal transduction target which will be of some interest to explore.
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Affiliation(s)
- Y T Ma
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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43
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Lim YH, Yokoigawa K, Esaki N, Soda K. A new amino acid racemase with threonine alpha-epimerase activity from Pseudomonas putida: purification and characterization. J Bacteriol 1993; 175:4213-7. [PMID: 8320235 PMCID: PMC204851 DOI: 10.1128/jb.175.13.4213-4217.1993] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We have found that Pseudomonas putida ATCC 17642 cells grown in a medium containing D-threonine as the sole nitrogen source produce an enzyme that catalyzes epimerization of threonine. Proton nuclear magnetic resonance analysis of the enzyme reaction in deuterium oxide clearly showed epimerization from L- to D-allo-threonine and also from D- to L-allo-threonine. This is the first example of an enzyme that was clearly shown to epimerize threonine. The enzyme has been purified to homogeneity, which was shown by polyacrylamide gel electrophoresis. The enzyme has a molecular weight of about 82,000 and consists of two subunits identical in molecular weight (about 41,000). The enzyme contains 1 mol of pyridoxal 5'-phosphate per mol of subunit as a cofactor, and its absorption spectrum exhibits absorption maxima at 280 and 420 nm. The enzyme catalyzes not only epimerization of threonine by stereoconversion at the alpha position but also racemization of various amino acids, except acidic and aromatic amino acids. The enzyme is similar to amino acid racemase with low substrate specificity (EC 5.1.1.10) in enzymological properties but is distinct from it in the action on threonine.
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Affiliation(s)
- Y H Lim
- Institute for Chemical Research, Kyoto University, Japan
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44
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Abstract
Neuroleptic medications are prescribed to millions of patients, but their use is limited by potentially irreversible extrapyramidal side effects. Haloperidol shows striking structural similarities to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which produces parkinsonism apparently through inhibition of NADH:ubiquinone oxidoreductase (complex I) of the mitochondrial electron transport chain. We now report that haloperidol, chlorpromazine, and thiothixene inhibit complex I in vitro in rat brain mitochondria. Clozapine, an atypical antipsychotic reported to have little or no extrapyramidal toxicity, also inhibits complex I, but at a significantly higher concentration. Neuroleptic treated patients have significant depression of platelet complex I activity similar to that seen in idiopathic Parkinson's disease. Complex I inhibition may be associated with the extrapyramidal side effects of these drugs.
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Affiliation(s)
- C Burkhardt
- Department of Neurology, University of Colorado School of Medicine, Denver
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45
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Yokoigawa K, Kawai H, Endo K, Lim YH, Esaki N, Soda K. Thermolabile alanine racemase from a psychotroph, Pseudomonas fluorescens: purification and properties. Biosci Biotechnol Biochem 1993; 57:93-7. [PMID: 7763424 DOI: 10.1271/bbb.57.93] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A psychotrophic bacterium that produces a thermolabile alanine racemase was isolated from raw milk, and identified as Pseudomonas fluorescens TM5-2. The enzyme was purified to homogeneity from the cell extract, and characterized to be compared with enzymes from mesophiles (Bacillus subtilis and Salmonella typhimurium) and a thermophile (Bacillus stearothermophilus). The enzyme has a molecular weight of about 76,000 and consists of two subunits identical in molecular weight (38,000). The enzyme contains two mol of pyridoxal 5'-phosphate per mol as a coenzyme. The amino acid composition was different from those of other alanine racemases in content of valine. The amino acid sequence of the amino terminal region (from 1Met to 25Gly) had 21-33% homology with those of other alanine racemases. Kinetic parameters of the enzyme were similar to those of other alanine racemases. The enzyme is extremely labile over 30 degrees C, and shows the high catalytic activity even at 0 degrees C; it is thermolabile and psychotrophic.
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Affiliation(s)
- K Yokoigawa
- Institute for Chemical Research, Kyoto University, Japan
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46
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Toyama H, Tanizawa K, Yoshimura T, Asano S, Lim YH, Esaki N, Soda K. Thermostable alanine racemase of Bacillus stearothermophilus. Construction and expression of active fragmentary enzyme. J Biol Chem 1991; 266:13634-9. [PMID: 1906880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Limited proteolysis studies on alanine racemase suggested that the enzyme subunit is composed of two domains (Galakatos, N. G., and Walsh, C. T. (1987) Biochemistry 26, 8475-8480). We have constructed a mutant gene that tandemly encodes the two polypeptides of the Bacillus stearothermophilus enzyme subunit cleaved at the position corresponding to the predicted hinge region. The mutant gene product purified was shown to be composed of two sets of the two polypeptide fragments and was immunologically identical to the wild-type enzyme. The mutant enzyme, i.e. the fragmentary alanine racemase, was active in both directions of the racemization of alanine. The maximum velocity (Vmax) was about half that of the wild-type enzyme, and the Km value was about double. Absorption and circular dichroism spectra of the fragmentary enzyme were similar to those of the wild-type enzyme. An attempt was made to separately express in Escherichia coli a single polypeptide corresponding to each domain, but no protein reactive with the antibody against the wild-type alanine racemase was produced. Therefore, it is suggested that the two polypeptide fragments can fold into an active structure only when they are co-translated and that they correspond to structural folding units in the parental polypeptide chain.
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Affiliation(s)
- H Toyama
- Laboratory of Microbial Biochemistry, Kyoto University, Japan
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47
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Lim YH, Gould MK. ATP-dependence of 125I-insulin binding by rat soleus muscle. Biochem Int 1983; 6:163-9. [PMID: 6433922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Muscle ATP levels were lowered by incubating rat soleus muscles under anaerobic conditions, or in the presence of 2:4-dinitrophenol (0.5 mM), EDTA (5 mM) or mannitol (400 mM). 125I-insulin binding, measured under equilibrium conditions at 25 degrees C, was reduced by 49-71% in ATP-depleted muscles. Insulin binding was also determined using two other procedures which minimized internalization of 125I-insulin: these were (a) 5 min at 25 degrees C, and (b) 24 h at 3 degrees C. Under these conditions, 125I-insulin binding was reduced by 28-55% in ATP-depleted muscles. These results confirm that in soleus muscle the effect of ATP-depletion on 125I-insulin binding is actually concerned with the binding step itself and not merely a reflection of ATP-dependent internalization of the bound hormone.
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