1
|
Yee MSL, Hii LW, Looi CK, Lim WM, Wong SF, Kok YY, Tan BK, Wong CY, Leong CO. Impact of Microplastics and Nanoplastics on Human Health. Nanomaterials (Basel) 2021; 11:496. [PMID: 33669327 PMCID: PMC7920297 DOI: 10.3390/nano11020496] [Citation(s) in RCA: 220] [Impact Index Per Article: 73.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 02/09/2021] [Accepted: 02/13/2021] [Indexed: 02/07/2023]
Abstract
Plastics have enormous impacts to every aspect of daily life including technology, medicine and treatments, and domestic appliances. Most of the used plastics are thrown away by consumers after a single use, which has become a huge environmental problem as they will end up in landfill, oceans and other waterways. These plastics are discarded in vast numbers each day, and the breaking down of the plastics from micro- to nano-sizes has led to worries about how toxic these plastics are to the environment and humans. While, there are several earlier studies reported the effects of micro- and nano-plastics have on the environment, there is scant research into their impact on the human body at subcellular or molecular levels. In particular, the potential of how nano-plastics move through the gut, lungs and skin epithelia in causing systemic exposure has not been examined thoroughly. This review explores thoroughly on how nanoplastics are created, how they behave/breakdown within the environment, levels of toxicity and pollution of these nanoplastics, and the possible health impacts on humans, as well as suggestions for additional research. This paper aims to inspire future studies into core elements of micro- and nano-plastics, the biological reactions caused by their specific and unusual qualities.
Collapse
Affiliation(s)
- Maxine Swee-Li Yee
- Centre of Nanotechnology and Advanced Materials, Faculty of Engineering, University of Nottingham Malaysia Campus, Jalan Broga, Semenyih 43500, Malaysia
| | - Ling-Wei Hii
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (L.-W.H.); (C.K.L.); (W.-M.L.)
- School of Postgraduate Studies, International Medical University, Kuala Lumpur 57000, Malaysia
- School of Pharmacy, International Medical University, Kuala Lumpur 57000, Malaysia
| | - Chin King Looi
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (L.-W.H.); (C.K.L.); (W.-M.L.)
- School of Postgraduate Studies, International Medical University, Kuala Lumpur 57000, Malaysia
| | - Wei-Meng Lim
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (L.-W.H.); (C.K.L.); (W.-M.L.)
- School of Pharmacy, International Medical University, Kuala Lumpur 57000, Malaysia
| | - Shew-Fung Wong
- Center for Environmental and Population Health, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (S.-F.W.); (Y.-Y.K.); (B.-K.T.); (C.-Y.W.)
- School of Medicine, International Medical University, Kuala Lumpur 57000, Malaysia
| | - Yih-Yih Kok
- Center for Environmental and Population Health, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (S.-F.W.); (Y.-Y.K.); (B.-K.T.); (C.-Y.W.)
- School of Health Sciences, International Medical University, 126, Jalan Jalil Perkasa 19, Bukit Jalil, Kuala Lumpur 57000, Malaysia
| | - Boon-Keat Tan
- Center for Environmental and Population Health, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (S.-F.W.); (Y.-Y.K.); (B.-K.T.); (C.-Y.W.)
- School of Medicine, International Medical University, Kuala Lumpur 57000, Malaysia
| | - Chiew-Yen Wong
- Center for Environmental and Population Health, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (S.-F.W.); (Y.-Y.K.); (B.-K.T.); (C.-Y.W.)
- School of Health Sciences, International Medical University, 126, Jalan Jalil Perkasa 19, Bukit Jalil, Kuala Lumpur 57000, Malaysia
| | - Chee-Onn Leong
- Center for Cancer and Stem Cell Research, Institute for Research, Development and Innovation (IRDI), International Medical University, Kuala Lumpur 57000, Malaysia; (L.-W.H.); (C.K.L.); (W.-M.L.)
- School of Pharmacy, International Medical University, Kuala Lumpur 57000, Malaysia
| |
Collapse
|
2
|
Boccara F, Tan BK, Chalouni M, Salmon Ceron D, Cinaud A, Esterle L, Gilbert C, Bani-Sadr F, Dabis F, Sogni P, Wittkop L. P5341Predictive factors of atherosclerotic cardiovascular diseases events in HIV-HVC co-infected patients: results from hepavih ANRS co13 cohort. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz746.0309] [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
Introduction
Several studies highlighted an increased risk of cardiovascular disease (CVD) in HIV-HCV co-infected patients without clearly identifying specific virologic factors associated with atherosclerotic CVD (ASCVD) events.
Purpose
Hence, we analyzed data collection from the French nationwide ANRS CO13 HEPAVIH cohort to determine the incidence of ASCVD events in HIV-HCV co-infected patients and the predictive factors associated with its occurrence.
Methods
The French multicenter nationwide ANRS CO13 HEPAVIH clinic-based cohort collected prospective clinical and biological data from HIV-HCV co-infected patients followed-up in 28 different university hospitals between December 2005 to November 2016. Participants with at least one year of follow-up were included. Primary outcome was the occurrence of major ASCVD events (cardiovascular death, acute coronary syndrome, coronary revascularization and stroke). Secondary outcomes were total ASCVD events including major ASCVD events and minor ASCVD events (peripheral arterial disease [PAD]). Incidence rates were estimated using Aalen-Johansen method and factors associated with ASCVD identified with Cox proportional hazards models.
Results
A total of 1213 patients were included: median age 45.4 years [42.1–49.0], 70.3% men, current smoking 70.2%, overweight 19.5%, liver cirrhosis 18.9%, chronic alcohol consumption 7.8%, diabetes mellitus (5.9%), personal history of CVD 2.7%, and statins use 4.1%. After a median follow-up of 5.1 years [3.9–7.0], 44 participants experienced at least one ASCVD event (26 major ASCVD event, and 20 a minor event). Incidences for total, major and minor ASCVD events were of 6.98 [5.19; 9.38], 4.01 [2.78; 6.00], and 3.17 [2.05; 4.92] per 1000 person-years, respectively. Personal history of CVD (Hazard Ratio (HR)=13.94 [4.25–45.66]), high total cholesterol (HR=1.63 [1.24–2.15]), low HDL cholesterol (HR=0.08 [0.02–0.34]) and undetectable HIV viral load (HR=0.41 [0.18–0.96]) were identified as independent factors associated with major ASCVD events while cirrhosis status, liver fibrosis and HCV sustained viral response were not.
Cumulative incidence of CV events
Conclusion
HIV-HCV co-infected patients experience a high incidence of ASCVD events both coronary and peripheral artery diseases. Traditional CV risk factors are the main determinants of ASCVD whereas undetectable HIV viral load seems to be protective. Management of cholesterol abnormalities and controlling viral load are essential to modify this high cardiovascular risk.
Acknowledgement/Funding
Agence Natoinale de Recherche sur le SIDA et les Hépatites virales
Collapse
Affiliation(s)
- F Boccara
- AP-HP - Hospital Saint Antoine, Paris, France
| | - B K Tan
- Hospital Cochin, Internal Medicine, Paris, France
| | - M Chalouni
- University of Bordeaux, ISPED, Bordeaux, France
| | - D Salmon Ceron
- Hospital Hotel-Dieu, Infectious Diseases Federation, Paris, France
| | - A Cinaud
- Hospital Hotel-Dieu, Cardiology, Paris, France
| | - L Esterle
- University of Bordeaux, ISPED, Bordeaux, France
| | - C Gilbert
- University of Bordeaux, ISPED, Bordeaux, France
| | - F Bani-Sadr
- University of Bordeaux, ISPED, Bordeaux, France
| | - F Dabis
- University of Bordeaux, ISPED, Bordeaux, France
| | - P Sogni
- Hospital Cochin, Hepatology, Paris, France
| | - L Wittkop
- Hospital Cochin, Hepatology, Paris, France
| |
Collapse
|
3
|
Lee WQ, Tan VKM, Choo HMC, Ong J, Krishnapriya R, Khong S, Tan M, Sim YR, Tan BK, Madhukumar P, Yong WS, Ong KW. Factors influencing patient decision-making between simple mastectomy and surgical alternatives. BJS Open 2018; 3:31-37. [PMID: 30734013 PMCID: PMC6354187 DOI: 10.1002/bjs5.50105] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 08/21/2018] [Indexed: 11/20/2022] Open
Abstract
Background Despite similar survival rates, breast‐conserving therapy (BCT) remains a distant second choice after simple mastectomy for patients with early‐stage breast cancer in Singapore. Uptake of reconstruction after mastectomy is also low (18 per cent). The aim of this study was to explore the factors influencing a patient's choice for mastectomy when eligible for BCT, and why patients decline reconstruction after mastectomy. Methods Patients from the National Cancer Centre Singapore, who were eligible for BCT but chose mastectomy without reconstruction, between December 2014 and December 2015 were included. An interviewer‐administered questionnaire focusing on patients' reasons for choosing mastectomy over BCT and not opting for immediate breast reconstruction after mastectomy was used. Tumour characteristics were retrieved from medical records. Spearman's rank correlation coefficient, Mann–Whitney U and Kruskal–Wallis tests were used to analyse the correlation between the patient's self‐rated influential factors and variables. Statistical significance was taken as P < 0·050. Results Ninety‐one patients were included (90·1 per cent response rate). The main reasons for choosing mastectomy over BCT were: fear of cancer recurrence (considered very important in 74 per cent), the perception that health outweighs breast retention (49 per cent) and the possibility of second surgery for margins (40 per cent). Key factors for rejecting immediate reconstruction after mastectomy were: patient‐perceived ‘old age’ (very important in 53 per cent), concern about two sites of surgery (42 per cent) and financial cost (29 per cent). Given a second chance, 19·8 per cent of patients would undergo BCT instead of mastectomy. Conclusion This study has identified the considerations that women in Singapore have when deciding on breast cancer surgery. Some perceptions need to be addressed for women to make a fully informed decision, especially as one‐fifth regret their initial choice.
Collapse
Affiliation(s)
- W Q Lee
- Yong Loo Lin School of Medicine National University of Singapore Singapore
| | - V K M Tan
- Division of Surgical Oncology National Cancer Centre Singapore Singapore.,Singhealth Duke-NUS Breast Centre National Cancer Centre Singapore Singapore
| | - H M C Choo
- Yong Loo Lin School of Medicine National University of Singapore Singapore
| | - J Ong
- Yong Loo Lin School of Medicine National University of Singapore Singapore
| | - R Krishnapriya
- Yong Loo Lin School of Medicine National University of Singapore Singapore
| | - S Khong
- Division of Surgical Oncology National Cancer Centre Singapore Singapore
| | - M Tan
- Division of Surgical Oncology National Cancer Centre Singapore Singapore
| | - Y R Sim
- Division of Surgical Oncology National Cancer Centre Singapore Singapore
| | - B K Tan
- Singhealth Duke-NUS Breast Centre National Cancer Centre Singapore Singapore.,Department of General Surgery Singapore General Hospital Singapore
| | - P Madhukumar
- Division of Surgical Oncology National Cancer Centre Singapore Singapore.,Singhealth Duke-NUS Breast Centre National Cancer Centre Singapore Singapore
| | - W S Yong
- Division of Surgical Oncology National Cancer Centre Singapore Singapore.,Singhealth Duke-NUS Breast Centre National Cancer Centre Singapore Singapore
| | - K W Ong
- Division of Surgical Oncology National Cancer Centre Singapore Singapore.,Singhealth Duke-NUS Breast Centre National Cancer Centre Singapore Singapore
| |
Collapse
|
4
|
Imoto Y, Kato A, Takabayashi T, Sakashita M, Norton JE, Suh LA, Carter RG, Weibman AR, Hulse KE, Stevens W, Harris KE, Peters AT, Grammer LC, Tan BK, Welch K, Conley DB, Kern RC, Fujieda S, Schleimer RP. Short-chain fatty acids induce tissue plasminogen activator in airway epithelial cells via GPR41&43. Clin Exp Allergy 2018; 48:544-554. [PMID: 29431874 DOI: 10.1111/cea.13119] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 11/30/2017] [Accepted: 12/22/2017] [Indexed: 12/11/2022]
Abstract
BACKGROUND Chronic rhinosinusitis (CRS) is a heterogeneous chronic inflammatory disease generally divided based on the presence or absence of nasal polyps (NPs). One of the features of NPs is excessive fibrin deposition, which is associated with down-regulation of tissue plasminogen activator (t-PA) in NPs. As t-PA is expressed in epithelial cells, and epithelium is readily accessible to topical therapies, identifying compounds that can mediate the induction of t-PA would be a potential new strategy for the treatment of NPs. OBJECTIVE The objective of this study was to determine whether short-chain fatty acids (SCFAs) can induce t-PA in airway epithelial cells via their known receptors GPR41 and GPR43. METHODS We performed immunohistochemistry (IHC) to determine whether receptors for SCFAs, known as G protein-coupled receptor 41/free fatty acid receptor 3 (GPR41/FFAR3) and GPR43/FFAR2, are expressed in nasal tissue. Primary normal human bronchial epithelial (NHBE) cells were stimulated with different concentrations of SCFAs to test induction of t-PA, which was analysed by expression of mRNA and protein. Mediation of responses by SCFA receptors was evaluated by specific receptor gene silencing with siRNA. RESULTS Immunohistochemistry study revealed that airway epithelial cells expressed GPR41 and GPR43. Acetic acid, propionic acid, butyric acid and valeric acid significantly induced t-PA expression from two- to tenfolds. The strongest inducer of t-PA from NHBE cells was propionic acid; cells stimulated with propionic acid released t-PA into the supernatant in its active form. Gene silencing of GPR41 and GPR43 revealed that induction of t-PA by SCFAs was dependent upon both GPR41 and GPR43. CONCLUSIONS AND CLINICAL RELEVANCE Short-chain fatty acids were shown to induce airway epithelial cell expression of t-PA via GPR41 and GPR43. Topical delivery of potent compounds that activate these receptors may have value by reducing fibrin deposition and shrinking nasal polyp growth.
Collapse
Affiliation(s)
- Y Imoto
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - A Kato
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - T Takabayashi
- Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - M Sakashita
- Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - J E Norton
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - L A Suh
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - R G Carter
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - A R Weibman
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - K E Hulse
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - W Stevens
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - K E Harris
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - A T Peters
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - L C Grammer
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - B K Tan
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - K Welch
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - D B Conley
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - R C Kern
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - S Fujieda
- Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - R P Schleimer
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| |
Collapse
|
5
|
Tan HK, Tan BK, Tan LK, Olofsson JI, Dahm-Kähler P, Brännström M. Authors' reply re: Starting a Uterus transplantation service: Notes from a small island. BJOG 2017; 125:516. [PMID: 29226565 DOI: 10.1111/1471-0528.15019] [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] [Subscribe] [Scholar Register] [Accepted: 11/05/2017] [Indexed: 11/29/2022]
Affiliation(s)
- H K Tan
- Department of Obstetrics and Gynaecology, Singapore General Hospital, Singapore, Singapore
| | - B K Tan
- Department of Plastic, Reconstructive & Aesthetic Surgery, Singapore General Hospital, Singapore, Singapore
| | - L K Tan
- Department of Obstetrics and Gynaecology, Singapore General Hospital, Singapore, Singapore
| | - J I Olofsson
- Reproductive Medicine, Karolinska University Hospital, Stockholm, Sweden.,Division of Obstetrics and Gynaecology, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - P Dahm-Kähler
- Department of Obstetrics and Gynaecology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - M Brännström
- Department of Obstetrics and Gynaecology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| |
Collapse
|
6
|
Feldman S, Kasjanski R, Poposki J, Hernandez D, Chen JN, Norton JE, Suh L, Carter RG, Stevens WW, Peters AT, Kern RC, Conley DB, Tan BK, Shintani-Smith S, Welch KC, Grammer LC, Harris KE, Kato A, Schleimer RP, Hulse KE. Chronic airway inflammation provides a unique environment for B cell activation and antibody production. Clin Exp Allergy 2017; 47:457-466. [PMID: 28000955 DOI: 10.1111/cea.12878] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 12/06/2016] [Accepted: 12/11/2016] [Indexed: 12/17/2022]
Abstract
BACKGROUND B cells play many roles in health and disease. However, little is known about the mechanisms that drive B cell responses in the airways, especially in humans. Chronic rhinosinusitis (CRS) is an inflammatory disease of the upper airways that affects 10% of Europeans and Americans. A subset of CRS patients develop nasal polyps (NPs), which are characterized by type 2 inflammation, eosinophils and group 2 innate lymphoid cells (ILC2s). We have reported that NP contain elevated levels of B cells and antibodies, making NP an ideal system for studying B cells in the airways. OBJECTIVE We sought to determine the mechanisms that drive B cell activation and antibody production during chronic airway inflammation. METHODS We analysed B cells from NP or tonsil, or after ILC2 coculture, by flow cytometry. Antibody production from tissue was measured using Luminex assays and the frequency of antibody-secreting cells by ELISpot. Formation of B cell clusters was assessed using immunohistochemistry. Expression of genes associated with B cell activation and class switch recombination was measured by qRT-PCR. RESULTS NP contained significantly elevated frequencies of plasmablasts, especially those that expressed the extrafollicular marker Epstein-Barr virus-induced protein 2 (EBI2), but significantly fewer germinal centre (GC) B cells compared with tonsil. Antibody production and the frequency of antibody-secreting cells were significantly elevated in NP, and there was evidence for local class switch recombination in NP. Finally, ILC2s directly induced EBI2 expression on B cells in vitro. CONCLUSIONS AND CLINICAL RELEVANCE Our data suggest there is a unique B cell activation environment within NP that is distinct from classic GC-mediated mechanisms. We show for the first time that ILC2s directly induce EBI2 expression on B cells, indicating that ILC2s may play an important role in B cell responses. B cell-targeted therapies may provide new treatment options for CRSwNP.
Collapse
Affiliation(s)
- S Feldman
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - R Kasjanski
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - J Poposki
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - D Hernandez
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - J N Chen
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - J E Norton
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - L Suh
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - R G Carter
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - W W Stevens
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - A T Peters
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - R C Kern
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - D B Conley
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - B K Tan
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - S Shintani-Smith
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - K C Welch
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - L C Grammer
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - K E Harris
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - A Kato
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - R P Schleimer
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - K E Hulse
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| |
Collapse
|
7
|
Abstract
OBJECTIVE To investigate the effects of obesity on superfertility. DESIGN Retrospective observational study. SETTING A tertiary referral implantation clinic. POPULATION Four hundred and fourteen women attending a tertiary implantation clinic with a history of recurrent miscarriage (RMC), over a 4-year period. METHODS Pattern of pregnancy loss and time to pregnancy intervals for each pregnancy were collected by medical staff from women with RMC. The women were categorised into normal, overweight and obese according to their body mass index (BMI). Kaplan-Meier curves were constructed estimating the cumulative probability of a spontaneous pregnancy over time. The pregnancy loss patterns were correlated with BMI and data were compared between the categories using the Kruskal-Wallis test. MAIN OUTCOME MEASURES Pregnancy loss pattern and time to pregnancy intervals. RESULTS Overall, 23.2, 51.4 and 64.2% of women conceived within first 1, 3 and 6 months, respectively. Obese women had cumulative pregnancy rates of 65.2 and 80% by three and 6 months, respectively, which was more than the cumulative pregnancy rates for women with normal BMI (49.2 and 65.8%). Comparison of survival curves indicated a significant difference in time to conceive for obese when compared with normal and overweight women (*P = 0.01), suggesting a higher prevalence of superfertility in obese women with RMC. CONCLUSIONS Our findings suggest that obese women may have a greater efficacy to achieve pregnancy, but with an increased risk of miscarriage, which may suggest the possible metabolic effects of obesity on endometrium.
Collapse
Affiliation(s)
- H M Bhandari
- Division of Reproductive Health, Clinical Science Research Laboratories, Warwick Medical School, University of Warwick, Coventry, UK.,Department of Obstetrics and Gynaecology, University Hospitals of Coventry and Warwickshire NHS Trust, Coventry, UK
| | - B K Tan
- Division of Reproductive Health, Clinical Science Research Laboratories, Warwick Medical School, University of Warwick, Coventry, UK.,Department of Obstetrics and Gynaecology, Birmingham Heartlands Hospital, Heart of England NHS Foundation Trust, Birmingham, UK
| | - S Quenby
- Division of Reproductive Health, Clinical Science Research Laboratories, Warwick Medical School, University of Warwick, Coventry, UK.,Department of Obstetrics and Gynaecology, University Hospitals of Coventry and Warwickshire NHS Trust, Coventry, UK
| |
Collapse
|
8
|
Abstract
Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory condition that affects a large proportion of the population world-wide and is associated with high cost of management and significant morbidity. Yet, there is a lack of population-based epidemiologic studies using current definitions of CRSwNP, and the mechanisms that drive pathogenesis in this disease remain unclear. In this review, we summarize the current evidence for the plethora of factors that likely contribute to CRSwNP pathogenesis. Defects in the innate function of the airway epithelial barrier, including diminished expression of antimicrobial products and loss of barrier integrity, combined with colonization by fungi and bacteria likely play a critical role in the development of chronic inflammation in CRSwNP. This chronic inflammation is characterized by elevated expression of many key inflammatory cytokines and chemokines, including IL-5, thymic stromal lymphopoietin and CCL11, that help to initiate and perpetuate this chronic inflammatory response. Together, these factors likely combine to drive the influx of a variety of immune cells, including eosinophils, mast cells, group 2 innate lymphoid cells and lymphocytes, which participate in the chronic inflammatory response within the nasal polyps. Importantly, however, future studies are needed to demonstrate the necessity and sufficiency of these potential drivers of disease in CRSwNP. In addition to the development of new tools and models to aid mechanistic studies, the field of CRSwNP research also needs the type of robust epidemiologic data that has served the asthma community so well. Given the high prevalence, costs and morbidity, there is a great need for continued research into CRS that could facilitate the development of novel therapeutic strategies to improve treatment for patients who suffer from this disease.
Collapse
Affiliation(s)
- K E Hulse
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | | | | | | |
Collapse
|
9
|
Poposki JA, Peterson S, Welch K, Schleimer RP, Hulse KE, Peters AT, Norton J, Suh LA, Carter R, Harris KE, Grammer LC, Tan BK, Chandra RK, Conley DB, Kern RC, Kato A. Elevated presence of myeloid dendritic cells in nasal polyps of patients with chronic rhinosinusitis. Clin Exp Allergy 2015; 45:384-93. [PMID: 25469646 DOI: 10.1111/cea.12471] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Revised: 11/23/2014] [Accepted: 11/28/2014] [Indexed: 12/14/2022]
Abstract
BACKGROUND Although chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by Th2 inflammation, the mechanism underlying the onset and amplification of this inflammation has not been fully elucidated. Dendritic cells (DCs) are major antigen-presenting cells, central inducers of adaptive immunity and critical regulators of many inflammatory diseases. However, the presence of DCs in CRS, especially in nasal polyps (NPs), has not been extensively studied. OBJECTIVE The objective of this study was to characterize DC subsets in CRS. METHODS We used real-time PCR to assess the expression of mRNA for markers of myeloid DCs (mDCs; CD1c), plasmacytoid DCs (pDCs; CD303) and Langerhans cells (LCs; CD1a, CD207) in uncinate tissue (UT) from controls and patients with CRS as well as in NP. We assayed the presence of DCs by immunohistochemistry and flow cytometry. RESULTS Compared to UT from control subjects (n = 15) and patients with CRS without NP (CRSsNP) (n = 16) and CRSwNP (n = 17), mRNAs for CD1a and CD1c were significantly elevated in NPs (n = 29). In contrast, CD207 mRNA was not elevated in NPs. Immunohistochemistry showed that CD1c(+) cells but not CD303(+) cells were significantly elevated in NPs compared to control subjects or patients with CRSsNP. Flow cytometric analysis showed that CD1a(+) cells in NPs might be a subset of mDC1s and that CD45(+) CD19(-) CD1c(+) CD11c(+) CD141(-) CD303(-) HLA-DR(+) mDC1s and CD45(+) CD19(-) CD11c(+) CD1c(-) CD141(high) HLA-DR(+) mDC2s were significantly elevated in NPs compared to UT from controls and CRSsNP, but CD45(+) CD11c(-) CD303(+) HLA-DR(+) pDCs were only elevated in NPs compared to control UT. CONCLUSION AND CLINICAL RELEVANCE Myeloid DCs are elevated in CRSwNP, especially in NPs. Myeloid DCs thus may indirectly contribute to the inflammation observed in CRSwNP.
Collapse
Affiliation(s)
- J A Poposki
- Division of Allergy-Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Weickert MO, Hodges P, Tan BK, Randeva HS. Neuroendocrine and endocrine dysfunction in the hyperinsulinemic PCOS patient: the role of metformin. MINERVA ENDOCRINOL 2012; 37:25-40. [PMID: 22382613] [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: 05/31/2023]
Abstract
Metformin is a widely used and extensively studied insulin sensitising drug for the treatment of women with polycystic ovary syndrome (PCOS), with various actions in tissues responding to insulin that include the liver, skeletal muscle, adipose tissue, the endothelium of blood vessels, and the ovaries. Treatment of PCOS women with metformin has been shown to reduce fasting glucose levels, blood pressure, and serum androgens; further effects of metformin in women with PCOS may include direct effects on the central nervous system; and indirect effects via the modification of gut hormone and adipokine synthesis and/or secretion. A number of "novel" adipokines and metabolic factors have been recently identified which may play a role both in the pathogenesis and the treatment of women with PCOS. We here discuss recent advances in the area, with a focus on neuroendocrine and endocrine dysfunctions in women with PCOS and the potential role of metformin in this context.
Collapse
Affiliation(s)
- M O Weickert
- Warwickshire Institute for the Study of Diabetes, Endocrinology and Metabolism, University Hospitals Coventry and Warwickshire NHS Trust, Coventry, UK.
| | | | | | | |
Collapse
|
11
|
Keswani A, Chustz RT, Suh L, Carter R, Peters AT, Tan BK, Chandra R, Kim SH, Azam T, Dinarello CA, Kern RC, Schleimer RP, Kato A. Differential expression of interleukin-32 in chronic rhinosinusitis with and without nasal polyps. Allergy 2012; 67:25-32. [PMID: 21899560 DOI: 10.1111/j.1398-9995.2011.02706.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [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: 12/24/2022]
Abstract
BACKGROUND Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by local inflammation of the upper airways and sinuses and is frequently divided into polypoid CRS (CRSwNP) and nonpolypoid CRS (CRSsNP). However, the mechanism of inflammation in CRS has still not been fully elucidated. The aim of the study was to investigate the role of interleukin-32 (IL-32), a recently discovered proinflammatory cytokine, in CRS. METHODS We collected nasal epithelial cells and nasal tissue from patients with CRS and control subjects. We assayed mRNA for IL-32 by real-time PCR and measured IL-32 protein using ELISA, Western blot, and immunohistochemistry. RESULTS The expression of mRNA for IL-32 was elevated in epithelial cells from uncinate tissue from patients with CRSsNP compared with patients with CRSwNP (P < 0.05), control subjects (P=0.06), and epithelial cells from nasal polyp (NP) tissue (P < 0.05). Production of IL-32 was induced by IFN-γ, TNF, and dsRNA in primary airway epithelial cells. In whole-tissue extracts, the expression of IL-32 protein was significantly elevated in patients with CRSwNP compared with patients with CRSsNP and control subjects. Immunohistochemistry data showed that IL-32 was detected in mucosal epithelial cells and inflammatory cells in the lamina propria. Levels of IL-32 were correlated with the levels of CD3 and macrophage mannose receptor in NP tissue. Immunofluorescence data showed IL-32 co-localization with CD3-positive T cells and CD68-positive macrophages in NPs. CONCLUSION Overproduction of IL-32 may be involved in the pathogenesis of CRS, although the role of IL-32 in the inflammation in CRSsNP and CRSwNP may be different.
Collapse
Affiliation(s)
- A Keswani
- Division of Allergy-Immunology, Northwestern University Feinberg School of Medicine, 240 E. Huron,Chicago, IL 60611, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Tan BK, Chen J, Adya R, Randeva HS. Phosphoprotein enriched in diabetes gene product (Ped/pea-15) is increased in omental adipose tissue of women with the polycystic ovary syndrome: ex vivo regulation of ped/pea-15 by glucose, insulin and metformin. Diabetes Obes Metab 2011; 13:181-4. [PMID: 21199270 DOI: 10.1111/j.1463-1326.2010.01329.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Polycystic ovary syndrome (PCOS), the commonest endocrine disorder in women, is characterized by an altered steroid milieu and is associated with insulin resistance and type 2 diabetes mellitus (T2DM). Phosphoprotein enriched in diabetes gene product (Ped/pea-15) regulates glucose metabolism and is increased in T2DM. Our novel data indicate that Ped/pea-15 mRNA expression and protein levels are significantly increased in omental adipose tissue (AT) from PCOS women compared to matched controls (p < 0.01); Ped/pea-15 levels in subcutaneous AT were not significantly different. Furthermore, Ped/pea-15 mRNA expression and protein levels were higher in omental compared to subcutaneous AT in PCOS subjects (p < 0.01); however, in control subjects, this was not significant. Glucose was predictive of omental AT Ped/pea-15 mRNA expression (p = 0.045). Importantly, glucose and insulin increased whereas metformin significantly decreased Ped/pea-15 levels in human omental AT explants. Our findings should serve to promote further research on Ped/pea-15 biology.
Collapse
|
13
|
|
14
|
Tan BK, Syed F, Lewandowski KC, O'Hare JP, Randeva HS. Circadian oscillation of circulating prothrombotic thrombospondin-1: ex vivo and in vivo regulation by insulin. J Thromb Haemost 2008; 6:1827-30. [PMID: 18853485 DOI: 10.1111/j.1538-7836.2008.03123.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
15
|
Tan BK, Saunier CF, Cotton F, Gueugniaud PY, Piriou V. [Thoracoabdominal CT scan: a useful tool for the diagnosis of air embolism during an endoscopic retrograde cholangiopancreatography]. ACTA ACUST UNITED AC 2008; 27:240-3. [PMID: 18313255 DOI: 10.1016/j.annfar.2007.12.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 12/19/2007] [Indexed: 02/07/2023]
Abstract
We report the case of an 82-year-old woman treated with biliary stents for an ampulloma of Vater's papilla, with recurrent stenosis of the common bile duct. She was hospitalized with a cholestasis. An endoscopic retrograde cholangiopancreatography (ERCP) was scheduled to change the biliary stent for a metallic one, under general anaesthesia, with oral intubation. The ERCP was performed initially without any complication, but as the metallic biliary stent was placed, an air embolism occurred and a cardiac arrest happened immediately. The etiologic diagnosis was quickly confirmed by an injected multislice body-scan, which showed liver, right heart and brain gas embolism. Cardiopulmonary resuscitation allowed a complete haemodynamic recovery but a poor neurological recovery. The patient was transferred in intensive care unit, were she died 12 days after, despite hyperbaric oxygen therapy and the disappearance of the air embolism on the following computed tomography scan. This case may be useful to recall the utility of a body-scan for the diagnosis, treatment and follow-up of an air embolism during ERCP.
Collapse
Affiliation(s)
- B K Tan
- Service d'anesthésie-réanimation, centre hospitalier Lyon-Sud, université Claude-Bernard, Lyon-1, 69395 Pierre-Bénite cedex, France
| | | | | | | | | |
Collapse
|
16
|
Tan BK, Chen J, Digby JE, Keay SD, Kennedy CR, Randeva HS. Upregulation of adiponectin receptor 1 and 2 mRNA and protein in adipose tissue and adipocytes in insulin-resistant women with polycystic ovary syndrome. Diabetologia 2006; 49:2723-8. [PMID: 17001470 DOI: 10.1007/s00125-006-0419-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 07/24/2006] [Indexed: 12/19/2022]
Abstract
AIMS/HYPOTHESIS Polycystic ovary syndrome (PCOS) is a multifaceted metabolic disease linked with insulin resistance (IR) and obesity. Adiponectin, which is lower in IR states, exerts its glucose-lowering and anti-inflammatory effects by activating two receptors, ADIPOR1 and ADIPOR2. There are no data on the relative expression of these receptors in adipose tissue of PCOS women. METHODS We investigated the expression of adiponectin receptors from corresponding s.c. and omental (o.m.) adipose tissue in women with PCOS compared with matched non-PCOS women. As there is a disturbance in the steroid milieu in PCOS women, we also assessed the effects of testosterone and oestradiol on adiponectin receptors using adipocytes and adipocyte explants. Real-time RT-PCR and western blotting were used to assess the relative adiponectin receptor mRNA expression and protein production, respectively. Biochemical measurements were performed in our hospital's laboratory. RESULTS We are the first to describe adiponectin receptor expression and production, in corresponding s.c. and o.m. human adipose tissues at the mRNA and protein level. We demonstrate the upregulation of mRNA expression and protein production of adiponectin receptors in women with PCOS, in s.c. and o.m. adipose tissue. Treatment of adipose tissue explants and adipocytes with testosterone and oestradiol induced the expression of adiponectin receptor mRNA and protein. There was a significant positive association between ADIPOR1/R2 expression and homeostasis model assessment, testosterone, oestradiol and triglycerides and a negative relationship with sex hormone-binding globulin. CONCLUSIONS/INTERPRETATION The precise reason for the upregulation of adiponectin receptors seen in PCOS women, a pro-diabetic state, is unknown, but it appears that sex steroids may play a role in their regulation in adipose tissue.
Collapse
Affiliation(s)
- B K Tan
- Endocrinology and Metabolism Group, Clinical Sciences Research Institute, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK
| | | | | | | | | | | |
Collapse
|
17
|
Lewandowski KC, Komorowski J, Mikhalidis DP, Bienkiewicz M, Tan BK, O'Callaghan CJ, Lewinski A, Prelevic G, Randeva HS. Effects of hormone replacement therapy type and route of administration on plasma matrix metalloproteinases and their tissue inhibitors in postmenopausal women. J Clin Endocrinol Metab 2006; 91:3123-30. [PMID: 16705077 DOI: 10.1210/jc.2005-2789] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
BACKGROUND Matrix metalloproteinases (MMPs) are implicated in numerous disease states including cardiovascular disease and cancer. Because recent studies have shown a detrimental effect of hormone replacement therapy on cardiovascular disease and breast cancer, we investigated whether there are any differences in the concentrations of MMPs and their tissue inhibitors (TIMPs) in women receiving various forms of postmenopausal therapy. MATERIAL AND METHODS A total of 195 healthy postmenopausal women were assessed: 46 were taking tibolone, 47 were taking transdermal estradiol, 46 were taking conjugated equine estrogens (CEE), and 56 were not taking any menopausal therapy (CTR). Plasma levels of MMP-2 and -9 and TIMP-1 and TIMP-2 were measured by ELISA methods. RESULTS MMP-9 levels were significantly higher in the CEE group in comparison with healthy women not receiving menopausal therapy (P < 0.05). In contrast, MMP-9 levels in the tibolone group were significantly lower than in any other group (P < 0.01, compared with transdermal estradiol and CTR, and P < 0.001, compared with CEE). MMP-9 to TIMP-1 ratio was also significantly higher in the CEE, compared with CTR (P < 0.05), and lower in the tibolone group (P < 0.01, compared with all groups). MMP-2 levels were higher in the CEE group, compared with healthy women not receiving any menopausal therapy, and women taking tibolone (P < 0.05). CONCLUSIONS Our study demonstrates differential effects of various forms of postmenopausal therapy on serum levels of MMP-9 and MMP-2. It remains to be established whether these differences might be associated with differences in risks of cardiovascular disease and cancer in these women.
Collapse
Affiliation(s)
- K C Lewandowski
- Molecular Medicine Group, Department of Biological Sciences, The University of Warwick, Coventry CV4 7AL, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Lewandowski KC, Komorowski J, O'Callaghan CJ, Tan BK, Chen J, Prelevic GM, Randeva HS. Increased circulating levels of matrix metalloproteinase-2 and -9 in women with the polycystic ovary syndrome. J Clin Endocrinol Metab 2006; 91:1173-7. [PMID: 16338908 DOI: 10.1210/jc.2005-0648] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
INTRODUCTION Matrix metalloproteinases (MMPs) have been implicated in various pathological processes including inflammatory response, cardiovascular disease, and recently also in ovarian dysfunction. Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women of reproductive age and is characterized by chronic anovulation, insulin resistance, and increased prevalence of cardiovascular risk factors. Circulating levels of MMPs and their tissue inhibitors (TIMPs) so far have not been assessed in the PCOS. MATERIALS AND METHODS Serum levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 were measured in 23 women with PCOS [age (mean +/- sd), 30.5 +/- 6.7 yr; body mass index, 35.8 +/- 7.5 kg/m2] and 22 healthy, regularly menstruating women (age, 29.4 +/- 5.6; body mass index, 31.7 +/- 9.2 kg/m2). RESULTS Women with PCOS had significantly higher concentrations of MMP-2 (999.8 +/- 155 vs. 521.8 +/- 242 ng/ml; P < 0.001), MMP-9 (592.4 +/- 279 vs. 345 +/- 309; P = 0.007), and TIMP-1 levels (823.8 +/- 145 vs. 692 +/- 210 ng/ml; P = 0.02) than control healthy women. There was no difference in TIMP-2 levels (47.3 +/- 30 vs. 44.4 +/- 39.7 ng/ml; P = 0.21) between women with PCOS and controls. CONCLUSIONS Obese women with PCOS have elevated serum concentrations of MMP-2 and -9. It might be hypothesized that elevated MMP concentrations may be related to increased cardiovascular risk in PCOS and/or menstrual irregularities associated with this syndrome.
Collapse
Affiliation(s)
- K C Lewandowski
- Molecular Medicine Group, Department of Biological Sciences, The University of Warwick, Coventry CV4 7AL, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
19
|
Affiliation(s)
- M W C H'ng
- Department of Orthopaedics, Tan Tock Seng Hospital, Singapore
| | | | | |
Collapse
|
20
|
Affiliation(s)
- T J Clark
- Department of Obstetrics and Gynaecology, Walsgrave Hospital, Coventry, UK
| | | | | |
Collapse
|
21
|
Pritlove DC, Tan BK, de Wit NCJ, Vatish M. Emerging technologies for the identification of therapeutic targets for the management of pre-eclampsia. Expert Opin Ther Targets 2004; 8:507-14. [PMID: 15584857 DOI: 10.1517/14728222.8.6.507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Pre-eclampsia is a common and serious complication of pregnancy characterised by hypertension and proteinuria. Genetic and environmental factors influence the occurrence and progression of the disease. Emerging experimental systems and increasingly specific analytical methods for the study of differences between normal and pre-eclamptic placentae are close to identifying specific indicators of disease, which may allow early diagnosis and intervention and reveal targets against which therapeutic agents can be developed.
Collapse
|
22
|
Tan BK, Chen HC, He TM, Song IC. Flap prefabrication - the bridge between conventional flaps and tissue-engineered flaps. Ann Acad Med Singap 2004; 33:662-6. [PMID: 15536673] [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: 05/01/2023]
Abstract
Flap prefabrication is one of the most exciting areas in Plastic Surgery because of its bridging role between conventional reconstructive surgery and tissue engineering. Using this technique,tissues such as bone, cartilage, skin and muscle can be preassembled to form precise composites that will fit any defect. In pre-lamination, for example, an ear may be created by burying cartilage underneath forearm skin and later harvested as a skin-cartilage composite free flap to replace the missing part. Vascular induction is yet another means of customising flaps where new blood supply is introduced to create transplantable tissue. For example, bone chips wrapped in avascular carrier such as muscle can become vascularised grafts. Our experiment describes jejunal prefabrication in a rat model using the same technique. Intestinal segments wrapped in muscle flaps become independent of their mesenteric blood supply by "parasitising" on the muscle's blood supply. This idea arose from our initial observations that intestinal segments transferred to the neck to reconstruct the oesophagus could survive accidental disruption of the pedicle if sufficient time had elapsed. Clearly, the bowel had picked up new blood supply from its bed. Subsequently, jejunal prefabrication was used to reconstruct the oesophagus in a patient in whom there were no recipient vessels for free jejunal transfer. The pedicled latissimus dorsi muscle flap was used as a carrier for the jejunum. Another application of this idea could be in the area of allogeneic trachea or pancreatic transplantation, since present-day techniques have yet to overcome problems such as insufficient vascularity and unpredictable transplant survival. Future applications incorporating biomaterials and cultured cells will usher in the era of tissue-engineered flaps.
Collapse
Affiliation(s)
- B K Tan
- Department of Plastic Surgery, Singapore General Hospital, Singapore.
| | | | | | | |
Collapse
|
23
|
Abstract
In the present study, we have examined the possible mechanism of the hypoglycemic action of the semi-purified fractions of an ethanolic extract of Averrhoa bilimbi Linn (Oxalidaceae) leaves (ABe) in streptozotocin-diabetic male Sprague-Dawley (SD) rats. The ABe was partitioned with water and butanol to yield a butanol-soluble fraction (BuF) and a water-soluble fraction (AF). The AF was further partitioned with ethyl acetate and hexane to obtain ethyl acetate (EF) and hexane (HF) soluble fractions. The hypoglycemic property of each fraction was assessed by the oral glucose tolerance test (OGTT) at a dose of 125-mg/kg-body weight in streptozotocin (STZ)-diabetic rats (STZ 60 mg/kg i.p.). Fractions AF, BuF and the reference drug metformin (500 mg/kg body weight), produced significant blood glucose-lowering effect in the diabetic rats when compared to the vehicle (distilled water). In the long-term study, the diabetic rats were randomly divided into 4 groups and treated orally by gavage with vehicle, AF (125 mg/kg body weight), BuF (125 mg/kg body weight), and metformin (500 mg/kg body weight) respectively twice a day for 14 days. On day 7 and day 14, AF and BuF, like the reference drug, metformin, lowered the fasting blood glucose concentration significantly (P < 0.05) when compared with the vehicle. The serum insulin level was significantly increased in the AF-treated rats only on day 14 when compared to that in the vehicle-treated rats on day zero (P < 0.05). The serum insulin level in BuF-treated rats was also significantly higher (P < 0.05) on both day 7 and day 14 compared to that on day zero. Hepatic glucose-6-phosphatase activity was significantly lower (P<0.05) in AF- and metformin-treated groups, but not in BuF-treated groups, compared to that in vehicle-treated group. However, there was no change in hepatic glycogen content in AF-, BuF- and metformin-treated group compared to the vehicle-treated group. These results indicate that AF is more potent than BuF in the amelioration of hyperglycemia in STZ-diabetic rats and is a potential source for the isolation of new orally active agent(s) for anti-diabetic therapy.
Collapse
Affiliation(s)
- P N Pushparaj
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore
| | | | | |
Collapse
|
24
|
Rohner D, Tan BK, Song C, Yeow V, Hammer B. Repair of composite zygomatico-maxillary defects with free bone grafts and free vascularized tissue transfer. J Craniomaxillofac Surg 2001; 29:337-43. [PMID: 11777351 DOI: 10.1054/jcms.2001.0253] [Citation(s) in RCA: 12] [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: 11/18/2022] Open
Abstract
INTRODUCTION Three-dimensional repair of the zygomatico-maxillary defect calls for an elaborate technique to achieve facial symmetry and correct globe position. We present a technique, which combines the use of a free vascularized soft tissue flap and free bone grafts for repair of composite zygomatico-maxillary defects. PATIENTS Three patients that underwent radical resection of the maxilla and the zygoma have undergone facial reconstruction using this technique. The mean follow up was 9 months. METHODS The key points of this technique are: (1) precise reconstruction of the zygomatico-maxillary complex including the orbit; (2) creation of a skeletal framework for canthopexy and suspension of the free flap; (3) repair of through-and-through soft tissue defects with a folded musculocutaneous free flap; and (4) simultaneous harvesting and reconstruction using two surgical teams to reduce the duration of surgery. RESULTS Reconstruction of the zygomatico-maxillary complex could be successfully accomplished in a single surgical procedure. CONCLUSION This paper presents a method of repairing zygomatico-maxillary defects with free bone grafts and vascularized soft tissue. However, this concept has yet to be reviewed in the long term.
Collapse
Affiliation(s)
- D Rohner
- Department of Plastic Surgery, Singapore General Hospital, Singapore.
| | | | | | | | | |
Collapse
|
25
|
Lim BH, Tan BK, Peng YP. Digital replantations including fingertip and ring avulsion. Hand Clin 2001; 17:419-31, viii-ix. [PMID: 11599210] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To reduce ischemic time and yet achieve a high-quality repair, the replantation team should be well organized. The team should be conversant with microvascular techniques and employ efficient methods of tendon repair and bone fixation. Developments in instrumentation and technique in recent years have improved success rates and consequently enlarged the indications for replantation surgery. Nevertheless, the economics of care and long-term functional outcome should not be overlooked, and these issues remain unresolved in the replantation versus terminalization question. The authors address topics relevant to replantation, including techniques and complications of digital replantation, ring avulsion injuries, and distal replantation.
Collapse
Affiliation(s)
- B H Lim
- Departments of Orthopaedic Surgery, Hand and Reconstructive Microsurgery, National University Hospital of Singapore, Singapore.
| | | | | |
Collapse
|
26
|
Tan KC, Tan BK. 5th Yahya Cohen Lecture: angiosomes and extension of skin flaps--anatomic study and clinical implications. Ann Acad Med Singap 2001; 30:93-7. [PMID: 11379425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- K C Tan
- Department of Plastic Surgery, Singapore General Hospital, 1 Hospital Drive, Singapore 169608
| | | |
Collapse
|
27
|
Abstract
This paper introduces a technique of lip reconstruction using free flaps in which recognisable landmarks are mimicked by strategic placement of flap junctions. The technique was applied in 15 patients undergoing reconstruction of combined cheek and lip defects using single (n= 9) or double (n= 6) free flaps. Attention to flap design and strategic placement of flap junctions successfully created the vermilion-cutaneous junction, oral commissure and labiomental groove. The presence of these distinguishing features improved the appearance of the reconstructed lip.
Collapse
Affiliation(s)
- F C Wei
- Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taipei, Taiwan
| | | | | | | | | |
Collapse
|
28
|
Ji XY, Tan BK, Zhu YZ. Salvia miltiorrhiza and ischemic diseases. Acta Pharmacol Sin 2000; 21:1089-94. [PMID: 11603281] [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: 02/21/2023] Open
Abstract
The demonstration of beneficial effects of salvia miltiorrhiza (DanShen) on ischemic diseases has revolutionized the management of angina pectoris, myocardial infarction (MI) or stroke in Chinese society. Experimental studies have shown that DanShen dilated coronary arteries, increased coronary blood flow, and scavenged free radicals in ischemic diseases, so that it reduced the cellular damage from ischemia and improved heart functions. Clinical trials also indicated that DanShen was an effective medicine for angina pectoris, MI, and stroke. This review will focus on DanShen's effects in angina pectoris, MI and stroke.
Collapse
Affiliation(s)
- X Y Ji
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
| | | | | |
Collapse
|
29
|
Zhang XF, Tan BK. Anti-diabetic property of ethanolic extract of Andrographis paniculata in streptozotocin-diabetic rats. Acta Pharmacol Sin 2000; 21:1157-64. [PMID: 11603293] [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: 02/21/2023] Open
Abstract
AIM To investigate the anti-diabetic effect of a crude ethanolic extract of Andrographis paniculata in normal and streptozotocin (STZ)-induced diabetic rats. METHODS & RESULTS Oral administration of the extract at different doses (0.1, 0.2, and 0.4 g/body weight) significantly reduced the fasting serum glucose level in STZ-diabetic rats compared to the vehicle (distilled water), but not in normal rats. This effect was dose-dependent. A similar result was seen with metformin (0.5 g/body weight). In the glucose tolerance test, an oral administration of the extract at the same doses suppressed the elevated glucose level in normal and diabetic rats, as did metformin. The effects were also dose-respondent. In the long-term experiment, the extract (0.4 g/body weight), metformin (0.5 g/body weight), and vehicle were given twice daily to diabetic rats for 14 d. On d 15, fasting serum glucose levels were found to be significantly lower in the extract- and metformin-treated groups (P < 0.001) than in the vehicle-treated group. The mean food and water intakes over 14 days were significantly lower in the extract-treated group (P < 0.05, P < 0.01, respectively) and also in the metformin-treated group (both P < 0.001) when compared to the vehicle-treated group. No significant change in insulin level was observed among the 3 groups of diabetic rats. The extract, like metformin, maintained the leptin levels after 14-d treatment, whereas this level was significantly decreased (P < 0.05) in the vehicle-treated group. The activity of hepatic glucose-6-phosphatase (G-6-Pase) was significantly reduced by the extract as well as by metformin (both P < 0.05). No significant difference in hepatic glycogen stores was noted among the 3 groups. The extract caused 49.8% reduction of fasting serum triglyceride levels, compared to 27.7% with metformin. However, neither the extract nor metformin significantly affected serum cholesterol level. CONCLUSION The ethanolic extract of A paniculata possesses antidiabetic property. Its antidiabetic effect may be attributed at least in part to increased glucose metabolism. Its hypotriglyceridemic effect is also beneficial in the diabetic state.
Collapse
Affiliation(s)
- X F Zhang
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, Singapore 117597, Singapore
| | | |
Collapse
|
30
|
Jayasurya A, Bay BH, Yap WM, Tan NG, Tan BK. Proliferative potential in nasopharyngeal carcinoma: correlations with metallothionein expression and tissue zinc levels. Carcinogenesis 2000; 21:1809-12. [PMID: 11023537 DOI: 10.1093/carcin/21.10.1809] [Citation(s) in RCA: 32] [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: 12/17/2022] Open
Abstract
Metallothionein (MT) is a cysteine-rich protein with pleiotropic functions and a high binding affinity for heavy metals. The present study was designed to examine the relationship between MT expression and tissue zinc levels in conjunction with cell proliferation in nasopharyngeal cancer (NPC). Proliferative activity in NPC was quantified by Ki67 immunolabelling and MT expression was determined by immunohistochemistry. Total zinc and subcellular zinc fractions were analysed by flame atomic absorption spectrometry. MT immunostaining was observed in the nuclei of NPC cells, with the percentage MT immunopositivity ranging from 3.0 to 59.7%. Thirteen tumours displayed weak MT staining and the remaining 11 showed moderate to strong immunostaining. There was a significant positive correlation between MT and Ki67 positivity (P = 0.0127). Tissue zinc levels were higher in NPC as compared with benign nasopharyngeal tissues (4.800 +/- 0.4610 versus 2.889 +/- 0.4045 microgram/g dry wt tissue, respectively; P = 0.0122). Nuclear zinc levels in NPC were significantly higher than levels in membrane and cytosolic fractions (mean zinc levels 1.4840 +/- 0.1489, 0.6286 +/- 0.0789 and 0.3014 +/- 0.0250 microgram/mg protein, respectively). A linear relationship was also observed between nuclear zinc levels and MT immunostaining (P = 0.0024) as well as with Ki67 immunopositivity (P = 0.0123). Our results show that MT and zinc are correlated with proliferative activity in NPC, providing further insights into the biology of this enigmatic and aggressive tumour.
Collapse
Affiliation(s)
- A Jayasurya
- Anatomy Department and Pharmacology Department, National University of Singapore, Kent Ridge, S119260, Singapore
| | | | | | | | | |
Collapse
|
31
|
Xu YJ, Chiang PY, Lai YH, Vittal JJ, Wu XH, Tan BK, Imiyabir Z, Goh SH. Cytotoxic prenylated depsidones from Garcinia parvifolia. J Nat Prod 2000; 63:1361-1363. [PMID: 11076552 DOI: 10.1021/np000141e] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Leaf extracts of Garcinia parvifolia provided relatively high yields of four novel, cytotoxic prenylated depsidones. The structures were determined mainly by detailed NMR spectral analysis and X-ray crystallography.
Collapse
Affiliation(s)
- Y J Xu
- Department of Chemistry, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Abstract
It has been reported that several cis-unsaturated fatty acids (c-UFAs) could increase doxorubicin (DOX) accumulation in cancer cells and hence elevate its cytotoxicity. However, some researchers showed that c-UFA pretreatment did not affect its cytotoxicity in special cell lines. It is possible that the different results occurred due to different cellular characteristics. We hypothesized that c-UFA treatment might modulate the activities of some antioxidant enzymes to affect the resistance of cells to DOX. In the present study, we examined how c-UFA pretreatment affected DOX cytotoxicity on mouse leukemia cell line, P388, and its resistant subline, P388/DOX, which we found to have significantly higher glutathione peroxidase (GPx) activity as well as P-glycoprotein (p-gp) overexpression. We chose two c-UFAs, gamma-linolenic acid (GLA) (18:3n-6) and docosahexaenoic acid (DHA) (22:6n-3). Cytotoxicity was measured by MTT (3-(4.5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and trypan blue exclusion assays. DOX accumulation and p-gp expression were measured by flow cytometry. The activities of catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and GPx were determined for both cell lines with and without treatment with GLA or DHA. Significant DOX accumulation occurred in both cell lines with GLA or DHA pretreatment, but without any change in p-gp expression in either cell line. Sensitivity to DOX cytotoxicity was improved by GLA or DHA pretreatment in P388/DOX in which only SOD activity was significantly increased, but not in the parental cell line P388 in which both SOD and CAT were significantly increased by the pretreatment. However, combined pretreatment of GLA or DHA with antioxidants, pyrrolidinedithiocarbamate (PDTC) or Vitamin C, could sensitize not only P388/DOX but also P388 cells to DOX. We conclude that the effects of c-UFA pretreatment on the sensitivity of cancer cells to DOX not only depend on the change in drug accumulation but also the change in the levels of antioxidant enzyme activities, and suggest that combined administration of c-UFAs, antioxidants, and DOX may be more effective in treating leukemia.
Collapse
Affiliation(s)
- Q Y Liu
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, Singapore, People's Republic of China
| | | |
Collapse
|
33
|
Abstract
The present study was designed to investigate the hypoglycemic and hypolipidemic activities of an ethanolic extract of Averrhoa bilimbi Linn. leaves (Oxalidaceae, Common name: Bilimbi) in streptozotocin (STZ)-diabetic rats. The optimal hypoglycemic dose (125 mg kg(-1)) was determined by performing the oral glucose tolerance test (OGTT) in both normal and STZ-diabetic rats. To investigate the effect of repeated administration of an ethanolic extract of Averrhoa bilimbi (ABe) leaves, diabetic rats were treated with vehicle (distilled water), ABe (125 mg kg(-1)) or metformin (500 mg kg(-1)) twice a day for 2 weeks. Like metformin, ABe significantly lowered blood glucose by 50% and blood triglyceride by 130% when compared with the vehicle. ABe also significantly increased the HDL-cholesterol concentrations by 60% compared with the vehicle. ABe thus significantly increased the anti-atherogenic index and HDL-cholesterol/total cholesterol ratio. However, like metformin, ABe did not affect total cholesterol and LDL-cholesterol concentrations, but significantly reduced the kidney lipid peroxidation level. These data show that ABe has hypoglycemic, hypotriglyceridemic, anti-lipid peroxidative and anti-atherogenic properties in STZ-diabetic rats.
Collapse
Affiliation(s)
- P Pushparaj
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore 119260, Singapore
| | | | | |
Collapse
|
34
|
Abstract
The 'internet-driven information age' is a term in common usage, implying that everyone can access all the information they need, when they need it. The purpose of this brief paper is to outline some web sources that highlight the possibilities and potential for accessing web-based knowledge. From this the clinician will be encouraged to follow leads along the labyrinth of links to a greater appreciation of how this resource can be used to shape their practice. Examples of web links are provided for: search engines; library-based sources, including medical databases and electronic journals; evidence-based practice databases, mail-groups; electronic conferences; research centres; and general health sources. Importantly, this review does not aspire to be all-inclusive, for the web changes, chameleon-like, to the seasons. The web is here to stay. It will provide the framework for much education and will guide clients to a greater appreciation of their disease or disability than ever before. It may ultimately be the tool through which health fund agents will promote best practice, including self-help to clients, and therefore direct discriminating individuals to select health practitioners who have been endorsed by professional and fund agencies as providing a contemporary service which conforms to evidence-based practice.
Collapse
Affiliation(s)
- K P Singer
- Centre for Musculoskeletal Studies, The University of Western Australia, Perth, Australia.
| | | |
Collapse
|
35
|
Li QT, Yeo MH, Tan BK. Lipid peroxidation in small and large phospholipid unilamellar vesicles induced by water-soluble free radical sources. Biochem Biophys Res Commun 2000; 273:72-6. [PMID: 10873566 DOI: 10.1006/bbrc.2000.2908] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [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: 11/22/2022]
Abstract
The susceptibility of small and large egg yolk phosphatidylcholine unilamellar vesicles to Fe(2+)/histidine-Fe(3+)- and Fenton reagent (Fe(2+)-H(2)O(2))-induced lipid peroxidation was evaluated by measuring the formation of thiobarbituric acid reactive substances (TBARS). It has been found that surface curvature or phospholipid packing exerts significant effect on the oxidative susceptibility of the unsaturated lipid bilayers and the highly curved and loosely packed small unilamellar vesicles (SUVs) exhibit much less resistance to the oxidative stress induced by the water-soluble free radical sources. The presence of lipid hydroperoxides in sonicated vesicles was excluded as the cause for higher level of lipid peroxidation in the phospholipid SUVs. Instead, the experimental results can be explained by the difference in ability of the water-soluble oxidants to penetrate the two types of lipid membranes. This hypothesis is supported by data obtained from fluorescence lifetime and quenching studies.
Collapse
Affiliation(s)
- Q T Li
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, Singapore, 119260.
| | | | | |
Collapse
|
36
|
Abstract
The forearm extension of the lateral arm flap was introduced on the basis of the vascular territory of the posterior radial collateral artery extending beyond the elbow into the forearm. However, there is controversy as to whether the posterior radial collateral artery extends as a single trunk below the elbow or if it terminates more proximally with only a rich vascular plexus extending beyond the elbow. The purpose of this study was to revisit the artery's anatomy in the region of the elbow and to study its distribution in the forearm. Using latex and barium-gelatin injections of the posterior radial collateral artery in ten cadaveric upper limbs, it was observed that terminal branching of the artery occurred 4.5 cm proximal to the lateral epicondyle of the humerus. Distal to the epicondyle, the terminal branches of the posterior radial collateral artery were seen to fan out as finely arborized branches supplying the lateral forearm skin. No single, constant vascular trunk to the forearm skin could be identified. Furthermore, in its distribution toward the periphery, the terminal branches of the posterior radial collateral artery took an increasingly superficial course. Proximal to the epicondyle, the vessels lay deep within the subcutaneous fat, whereas distal to the epicondyle, they were very close to skin. These findings suggest that lateral forearm skin cannot be islanded without risk of vascular disruption and that the distally sited flap should include skin proximal to the epicondyle for safety.
Collapse
Affiliation(s)
- B K Tan
- Department of Plastic Surgery, Singapore General Hospital
| | | |
Collapse
|
37
|
Abstract
1. Oxidative stress is believed to be a pathogenetic factor in the development of diabetic complications. In the present study, we investigated the ethanolic extract of the aerial parts of Andrographis paniculata for antihyperglycaemic and anti-oxidant effects in normal and streptozotocin-induced type I diabetic rats. 2. Normal and diabetic rats were randomly divided into groups and treated orally by gavage with vehicle (distilled water), metformin (500 mg/kg bodyweight) or the extract (400 mg/kg bodyweight), twice a day for 14 days. 3. At the end of the 14 day period, the extract, like metformin, significantly increased bodyweight (P < 0.01) and reduced fasting serum glucose in diabetic rats (P < 0.001) when compared with vehicle, but had no effect on bodyweight and serum glucose in normal rats. Levels of liver and kidney thiobarbituric acid-reactive substances (TBARS) were significantly increased (P < 0.0001, P < 0.01, respectively), while liver glutathione (GSH) concentrations were significantly decreased (P < 0.005) in vehicle-treated diabetic rats. Liver and kidney TBARS levels were significantly lower (P < 0.0001, P < 0.005, respectively), whereas liver GSH concentrations were significantly higher (P < 0.05) in extract- and metformin-treated diabetic rats compared with vehicle-treated diabetic rats. Andrographis paniculata significantly decreased kidney TBARS level (P < 0.005) in normal rats. Hepatic superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities were significantly lower in vehicle-treated diabetic rats compared with vehicle-treated normal rats. The extract, as well as metformin, significantly increased the activity of SOD and CAT, but had no significant effect on GSH-Px activity in diabetic rats. The extract and metformin did not produce significant changes in the activity of these anti-oxidant enzymes in normal rats. 4. Our results show that oxidative stress is evident in streptozotocin-diabetic rats and indicate that the ethanolic extract of A. paniculata not only possesses an antihyperglycaemic property, but may also reduce oxidative stress in diabetic rats.
Collapse
Affiliation(s)
- X F Zhang
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, Singapore
| | | |
Collapse
|
38
|
Abstract
The lower trapezius island myocutaneous flap is a useful flap in head and neck reconstruction. It is thin and pliable and can reach defects in most areas of the head and neck. Its usefulness in head and neck reconstruction has often been limited or discouraged by reports of significant failure rates. In this study, the vascular anatomy and clinical use of the extended lower trapezius myocutaneous flap based solely on the dorsal scapular artery system are elucidated, and experience gained performing 20 flaps over the past 5 years by using the extended lower trapezius myocutaneous flap is reported. The vascular anatomy of the dorsal scapular artery system is reviewed in 13 fresh cadaveric dissections by using methylene blue, latex injection studies, and radiologic examination.
Collapse
Affiliation(s)
- K C Tan
- Department of Plastic Surgery, Singapore General Hospital, Singapore.
| | | |
Collapse
|
39
|
Abstract
In-vitro cytotoxic screening of extracts of Nigella sativa L. seeds (Ranunculaceae) indicated cytotoxicity in the ethyl-acetate fraction (EAF) against different classes of cancer cell lines, P388, Molt4, Wehi 164, LL/2, Hep G2, SW620 and J82, as measured by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The ethyl-acetate column chromatographic fraction (CC-5) showed selectivity against Hep G2, Molt4, and LL/2. CC-5 was relatively non-toxic against human umbilical cord endothelial cells at 50 microg/ml. CC-5 had no stimulatory effect on mouse splenocytes as such. CC-5 and water fraction, however, enhanced the proliferative response in the presence of ConA (3 microg/ml), but not LPS (1 and 6 microg/ml). These data indicate that CC-5 possesses a potent cytotoxic effect as well as a potentiating effect on the cellular immune response. The mechanism whereby it produces this needs to be resolved.
Collapse
Affiliation(s)
- S M Swamy
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore
| | | |
Collapse
|
40
|
Xu YJ, Wu XH, Tan BK, Lai YH, Vittal JJ, Imiyabir Z, Madani L, Khozirah KS, Goh SH. Flavonol-cinnamate cycloadducts and diamide derivatives from Aglaia laxiflora. J Nat Prod 2000; 63:473-476. [PMID: 10785416 DOI: 10.1021/np990454d] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Leaf extracts of the Malaysian plant Aglaia laxiflora provided two cytotoxic compounds, a new rocaglaol rhamnoside (1), a known rocaglaol (2), new (but inactive) flavonol-cinnamaminopyrrolidine adducts (3-6), and their probable biosynthetic precursors (7 and trimethoxyflavonol). All structures were elucidated primarily by 2D NMR spectroscopy. The structure and stereochemistry of aglaxiflorin A (3) were confirmed by single-crystal X-ray crystallography.
Collapse
MESH Headings
- Animals
- Antineoplastic Agents, Phytogenic/isolation & purification
- Antineoplastic Agents, Phytogenic/pharmacology
- Crystallography, X-Ray
- Drug Screening Assays, Antitumor
- Heterocyclic Compounds, 3-Ring/isolation & purification
- Heterocyclic Compounds, 3-Ring/pharmacology
- Humans
- Leukemia P388/drug therapy
- Magnetic Resonance Spectroscopy
- Malaysia
- Mass Spectrometry
- Mice
- Molecular Conformation
- Plants, Medicinal/chemistry
- Rats
- Spectrometry, Mass, Fast Atom Bombardment
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- Y J Xu
- Department of Chemistry, National University of Singapore
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Affiliation(s)
- X Fei
- Department of Clinical Research, Singapore General Hospital, Singapore
| | | | | | | | | | | |
Collapse
|
42
|
Tsi D, Tan BK. The mechanism underlying the hypocholesterolaemic activity of aqueous celery extract, its butanol and aqueous fractions in genetically hypercholesterolaemic RICO rats. Life Sci 2000; 66:755-67. [PMID: 10680583 DOI: 10.1016/s0024-3205(99)00646-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [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: 10/16/2022]
Abstract
Drinking aqueous celery extract for 8 weeks caused a significant reduction in serum total cholesterol (TC) level in growing genetically hypercholesterolaemic (RICO) rats. In addition, administration of butanol fraction (Fbu) and aqueous fraction (Faq) of celery extract for 7 days by intraperitoneal (i.p.) infusion effectively decreased the serum TC and high-density lipoprotein cholesterol (HDL-C) levels of adult RICO rats. The 8-week study showed that oral intake of celery extract could enhance the 14C-cholesterol/metabolites excretion. The liver and small intestinal sterol synthesis were not affected. Also, long term drinking of aqueous celery extract did not lead to any undesirable side effects on liver functions. The Fbu and Faq lowered serum TC level mainly through increased bile acid excretion but not by modulating the activity of the rate-limiting enzyme for cholesterol biosynthesis, HMG-CoA reductase. Hence, the mechanism elucidated supports that suggested by the 8-week study. A preliminary chemical characterisation of Fbu and Faq fractions by thin layer chromatography (TLC) showed the presence of sugars and amino acids. There is a possibility that polar compounds with sugar or amino acid side chains(s) could contribute to the hypocholesterolaemic action of celery extract.
Collapse
Affiliation(s)
- D Tsi
- Department of Pharmacology, Faculty of Medicine, National University of Singapore, Singapore
| | | |
Collapse
|
43
|
Abstract
BACKGROUND The technique of percutaneous catheterization of the subclavian vein by the infraclavicular approach is dependent on the location of the subclavian vein in relation to the clavicle. The purpose of this study was to analyze the anatomic relationship between these two structures and how it is influenced by changes in shoulder positioning. METHODS Dissections of the infraclavicular region were performed in seven fresh cadavers and linear measurements made to determine the extent of overlap between the vein and the clavicle in different shoulder positions. RESULTS When the shoulder was in neutral position, the subclavian vein was overlapped by the medial third or more of the clavicle and this segment of bone was able to serve as a landmark for the vein. However, shoulder elevation displaced the clavicle cephalad and reduced the degree of overlap. Mild shoulder retraction increased the area of contact between the vein and the undersurface of the clavicle, whereas protraction lifted the clavicle off the vein. CONCLUSION Infraclavicular subclavian venipuncture should be performed with shoulders in a neutral position and also in slight retraction. An appreciation of the anatomic relationship between the clavicle and the subclavian vein is the key to successful execution of this technique.
Collapse
Affiliation(s)
- B K Tan
- Department of Plastic Surgery, Singapore General Hospital, Singapore
| | | | | | | |
Collapse
|
44
|
Zhang XF, Tan BK. Effects of an ethanolic extract of Gynura procumbens on serum glucose, cholesterol and triglyceride levels in normal and streptozotocin-induced diabetic rats. Singapore Med J 2000; 41:9-13. [PMID: 10783673] [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: 02/16/2023]
Abstract
AIM OF STUDY The aim was to demonstrate the effects of the leaves of Gynura procumbens (Lour.) Merr. on blood sugar and lipid levels in experimental animals. METHODOLOGY We obtained an ethanolic extract of the leaves of G. procumbens and monitored the effects of an oral administration of (i) different single doses of the extract on oral glucose tolerance in streptozotocin-induced diabetic and normal rats and (ii) fourteen doses over 7 days on serum cholesterol and triglyceride levels in streptozotocin-induced diabetic rats. Metformin and glibenclamide were used as positive control drugs. RESULTS The extract, at single doses of 50, 150 and 300 mg/kg orally, significantly suppressed the elevated serum glucose levels in diabetic rats; 150 mg/kg was found to be the optimum hypoglycaemic dose. The extract however did not significantly suppress the elevated serum glucose levels in normal rats, unlike glibenclamide. Metformin, but not glibenclamide, improved glucose tolerance in the diabetic rats. When the optimum dose was given to diabetic rats for 7 days, the extract significantly reduced serum cholesterol and triglyceride levels in these rats. CONCLUSION These results indicate that the leaves of G. procumbens may have biguanide-like activity.
Collapse
Affiliation(s)
- X F Zhang
- Department of Pharmacology, National University of Singapore, Singapore
| | | |
Collapse
|
45
|
Abstract
Skim milk cultured with lactic acid bacteria has been previously reported to reduce lipid peroxidation in rat livers. In this study, the effects of skim milk and cultured milk supplementation on peroxidative stress in brains of weanling rats were investigated. We observed a reduction of brain thiobarbituric acid reacting substances (TBARS) concentration in milk-supplemented animals as compared with controls. In brains of control rats, the superoxide dismutase (SOD) enzyme levels were significantly higher than those from the milk-supplemented animals. In addition, SOD activity in control animal brains had a positive correlation with the TBARS concentration. There was no significant differences in the brain glutathione-S-transferase (GST) levels of all the three groups of animals. The results suggest that milk supplementation may be beneficial in reducing peroxidative stress in the developing rat brain.
Collapse
Affiliation(s)
- B H Bay
- Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore.
| | | | | | | |
Collapse
|
46
|
Abstract
A significant benefit exists for a jejunal replacement of the cervical esophagus, if indicated. The absence of available recipient vessels may impede free tissue transfer. If vascular induction between a vascular carrier and the selected jejunal segment is done as a kind of flap prefabrication, the jejunal interposition flap can be used without the need for complex microsurgery.
Collapse
Affiliation(s)
- S Y Chang
- Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Taipei, Taiwan, ROC
| | | | | | | | | |
Collapse
|
47
|
Tan BK, Wei FC, Lutz BS, Lin CH. Strategies in multiple toe transplantation for bilateral type II metacarpal hand reconstruction. Hand Clin 1999; 15:607-12, viii. [PMID: 10563265] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Multiple toe transplantation has been established as an effective means of restoring prehensile function in the metacarpal hand. The attainable outcome, however, must be weighed against potential donor site morbidity. Restoration of prehensile function in bilateral type II metacarpal hands can be achieved by reconstructing three opposable digits in the dominant hand and two opposable digits in the nondominant hand. This article outlines the strategy for optimizing functional outcome and discusses the rationale behind toe selection to reduce donor morbidity.
Collapse
Affiliation(s)
- B K Tan
- Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Taipei, Taiwan, Republic of China
| | | | | | | |
Collapse
|
48
|
Tan BK, Wei FC, Chang KJ, Lutz BS, Chen SH. Combined third and fourth toe transplantation. Hand Clin 1999; 15:589-96, viii. [PMID: 10563263] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Multiple toe transplantation has been established as an effective technique for restoring prehensile ability in the metacarpal hand. The combined third and fourth toe transplant is a new toe transplant that has been developed for bilateral metacarpal hand reconstruction. Since 1991, the combined third and fourth toe transplant was added to the armamentarium of toe transplants for metacarpal hands, although its role in metacarpal hand reconstruction has not been described previously. This article introduces the indications for combined third and fourth toe transplant, outlines relevant vascular anatomy, and discusses technical considerations pertaining to toe harvest and transplantation.
Collapse
Affiliation(s)
- B K Tan
- Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Taipei, Taiwan, Republic of China
| | | | | | | | | |
Collapse
|
49
|
Ponraj D, Makjanic J, Thong PS, Tan BK, Watt F. The onset of atherosclerotic lesion formation in hypercholesterolemic rabbits is delayed by iron depletion. FEBS Lett 1999; 459:218-22. [PMID: 10518022 DOI: 10.1016/s0014-5793(99)01199-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [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: 11/23/2022]
Abstract
The theory that iron may play a significant role in atherogenesis by promoting the formation of free radicals is controversial. Previous results using the new technique of nuclear microscopy showed a seven-fold increase in iron concentrations within newly formed atherosclerotic lesions in hypercholesterolemic rabbits compared to healthy artery tissue. In a follow-up time sequence study described here, we show that iron accumulation occurs at the onset of lesion formation. In addition, weekly bleeding decreases the iron uptake into the artery wall and delays the onset of atherogenesis. These results provide direct evidence for a key role of iron in initiating atherogenesis.
Collapse
Affiliation(s)
- D Ponraj
- Research Centre for Nuclear Microscopy, Department of Physics, National University of Singapore, Singapore
| | | | | | | | | |
Collapse
|
50
|
Tay AG, Yeow VK, Tan BK, Sng K, Huang MH, Foo CL. A review of mandibular fractures in a craniomaxillofacial trauma centre. Ann Acad Med Singap 1999; 28:630-3. [PMID: 10597345] [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: 02/14/2023]
Abstract
This report is a retrospective review of 74 cases of mandibular fractures managed in a craniomaxillofacial trauma centre between January 1994 and May 1998. Demographic data revealed that 85% of the patient population were male, with a mean age of 27.5 years. The commonest causes of injury were motor vehicle accidents (48.6%), followed by assault (16.2%) and accidental falls (17.6%). In 25 patients (33.8%) the fractures were single. Of these, fractures of the condylar region were the most common (8 patients). The remaining patients sustained fractures in two or more anatomic sites. There were other associated facial fractures in 45.9% of patients. Trauma to other systems was present in 37.8%, with orthopaedic and neurosurgical injuries being the most common. Surgical management in the form of open reduction and internal fixation was carried out in 61 patients (82.4%). Maxillo-mandibular fixation was used as an adjunct to maintain occlusion and bony reduction in unstable and comminuted fractures (15 patients, 20.3%), and as the primary mode of treatment in patients with stable, undisplaced fractures, particularly condylar fractures, in which the pretraumatic occlusal relationship was not disrupted (9 patients, 12.2%). A successful outcome was defined as a stable and healed fracture, with restoration of functional occlusion, facial symmetry and facial aesthetics. Complications observed included temporomandibular joint dysfunction (10.8%), malocclusion (9.5%), infection (8.1%), implant exposure (5.4%), and non-union or delayed union (4.1%).
Collapse
Affiliation(s)
- A G Tay
- Department of Plastic Surgery, Singapore General Hospital, Singapore
| | | | | | | | | | | |
Collapse
|