76
|
Wan S, Stillwaugh L, Prichard H, Bowen J, Provost D. Evaluation of a 3D Ultrasound System for Image Guided Radiation Therapy for Prostate Cancer. Int J Radiat Oncol Biol Phys 2008. [DOI: 10.1016/j.ijrobp.2008.06.116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
77
|
|
78
|
Gong Y, Xi G, Wan S, Gu Y, Keep RF, Hua Y. Effects of aging on complement activation and neutrophil infiltration after intracerebral hemorrhage. ACTA NEUROCHIRURGICA. SUPPLEMENT 2008; 105:67-70. [PMID: 19066085 DOI: 10.1007/978-3-211-09469-3_14] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Intracerebral hemorrhage (ICH)-induced brain edema and neurological deficits are greater in aged rats than in young rats. Complement activation and neutrophil infiltration contribute to brain injury after ICH. In this study, we investigated the effects of aging on activation of the complement cascade and neutrophil influx following ICH. Male Sprague-Dawley rats (3 or 18 months old) received an infusion of 100 microL autologous blood into right caudate. Rats were killed at 1, 3, 7, and 28 days after ICH and the brains were sampled for immunohistochemistry and Western blot analysis. Levels of complement factor C9 and clusterin were used as markers for complement activation, and myeloperoxidase (MPO) staining was performed to detect neutrophil infiltration. Western blot analysis showed that complement C9 and clusterin levels in ipsilateral basal ganglia after ICH were higher in aged rats than in young rats (p < 0.05). Immunohistochemistry showed there were more C9- and clusterin-positive cells around the hematoma in aged rats. However, MPO-positive cells in ipsilateral basal ganglia were fewer in aged rats (p < 0.05) after ICH. Our results suggest that ICH causes more severe complement activation and less neutrophil infiltration in aged rats. Clarification of the mechanisms of brain injury after ICH in the aging brain should help develop new therapeutic strategies for ICH.
Collapse
|
79
|
Wan S, Underwood MJ. Cardiovascular Surgery in the Aging World. Intensive Care Med 2007. [DOI: 10.1007/978-0-387-49518-7_38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
80
|
Ong G, Rasidah N, Wan S, Cutter J. Outbreak of measles in primary school students with high first dose MMR vaccination coverage. Singapore Med J 2007; 48:656-61. [PMID: 17609829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
INTRODUCTION Indigenous cases of measles continue to occur in Singapore despite the implementation of a two-dose mumps, measles and rubella (MMR) vaccination policy in 1998. We investigated a measles outbreak that took place in a primary school from April 17 to May 6, 2004 to identify all cases, evaluate vaccine efficacy (VE) and implement outbreak control measures. METHODS A case of measles was defined as anyone having generalised rash and fever with or without cough, coryza or conjunctivitis during the outbreak period, and who had either laboratory-confirmed acute measles infection or was epidemiologically linked to a patient with laboratory-confirmed measles infection. Vaccination status was obtained from the studentos health booklet and confirmed with the National Immunisation Registry. Attack rates in unvaccinated (ARU) and vaccinated (ARV) students were calculated and VE was evaluated using the formula: VE (percent) = [(ARU-ARV) / ARU] x 100 percent. RESULTS Nine students, aged between eight and 14 years, from five classes in primary three and primary six, were epidemiologically linked to have measles. None of them had received the second dose of the MMR vaccine. 93 percent of students in the affected classes (n = 184) had prior documented evidence of receiving at least one dose of MMR vaccination, as compared to 96.5 percent for the entire school enrolment (n = 1,309). The attack rate was 1.2 percent in the vaccinated group and 53.8 percent in the unvaccinated group. The VE for the primary dose of MMR in the affected classes was 97.8 percent. CONCLUSION It is important to achieve a high coverage for the primary dose of MMR vaccine in order to prevent any potential outbreaks prior to receiving the booster dose.
Collapse
|
81
|
Howard S, Wan S, Freeman LJ. Congenital absence of the pulmonary valve. BRITISH HEART JOURNAL 2007; 93:779. [PMID: 17569799 PMCID: PMC1994462 DOI: 10.1136/hrt.2006.097535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
82
|
Seto SW, Au ALS, Lam TY, Chim SSC, Lee SMY, Wan S, Tjiu DCS, Shigemura N, Yim APC, Chan SW, Tsui SKW, Leung GPH, Kwan YW. Modulation by simvastatin of iberiotoxin-sensitive, Ca2+-activated K+ channels of porcine coronary artery smooth muscle cells. Br J Pharmacol 2007; 151:987-97. [PMID: 17558433 PMCID: PMC2042927 DOI: 10.1038/sj.bjp.0707327] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE Statins (3-hydroxy-3-methyl-glutaryl coenzyme A (HMG CoA) reductase inhibitors) have been demonstrated to reduce cardiovascular mortality. It is unclear how the expression level of HMG CoA reductase in cardiovascular tissues compares with that in cells derived from the liver. We hypothesized that this enzyme exists in different cardiovascular tissues, and simvastatin modulates the vascular iberiotoxin-sensitive Ca2+-activated K(+) (BK(Ca)) channels. EXPERIMENTAL APPROACHES Expression of HMG CoA reductase in different cardiovascular preparations was measured. Effects of simvastatin on BK(Ca) channel gatings of porcine coronary artery smooth muscle cells were evaluated. KEY RESULTS Western immunoblots revealed the biochemical existence of HMG CoA reductase in human cardiovascular tissues and porcine coronary artery. In porcine coronary artery smooth muscle cells, extracellular simvastatin (1, 3 and 10 microM) (hydrophobic), but not simvastatin Na+ (hydrophilic), inhibited the BK(Ca) channels with a minimal recovery upon washout. Isopimaric acid (10 microM)-mediated enhancement of the BK(Ca) amplitude was reversed by external simvastatin. Simvastatin Na+ (10 microM, applied internally), markedly attenuated isopimaric acid (10 microM)-induced enhancement of the BK(Ca) amplitude. Reduced glutathione (5 mM; in the pipette solution) abolished simvastatin -elicited inhibition. Mevalonolactone (500 microM) and geranylgeranyl pyrophosphate (20 microM) only prevented simvastatin (1 and 3 microM)-induced responses. simvastatin (10 microM ) caused a rottlerin (1 microM)-sensitive (cycloheximide (10 microM)-insensitive) increase of PKC-delta protein expression. CONCLUSIONS AND IMPLICATIONS Our results demonstrated the biochemical presence of HMG CoA reductase in different cardiovascular tissues, and that simvastatin inhibited the BK(Ca) channels of the arterial smooth muscle cells through multiple intracellular pathways.
Collapse
MESH Headings
- Adult
- Aged
- Animals
- Blotting, Western
- Caveolin 1/biosynthesis
- Cell Line
- Cell Line, Tumor
- Coronary Vessels/cytology
- Coronary Vessels/drug effects
- Coronary Vessels/physiology
- Dose-Response Relationship, Drug
- Enzyme Activation/drug effects
- Female
- Humans
- Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology
- Imidazoles/pharmacology
- In Vitro Techniques
- Male
- Membrane Potentials/drug effects
- Middle Aged
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/physiology
- Peptides/pharmacology
- Phorbol Esters/pharmacology
- Potassium Channels, Calcium-Activated/antagonists & inhibitors
- Potassium Channels, Calcium-Activated/metabolism
- Potassium Channels, Calcium-Activated/physiology
- Protein Kinase C-delta/metabolism
- Pyridines/pharmacology
- Simvastatin/chemistry
- Simvastatin/pharmacology
- Swine
Collapse
|
83
|
Wan S, Coleman FH, Travagli RA. Glucagon-like peptide-1 excites pancreas-projecting preganglionic vagal motoneurons. Am J Physiol Gastrointest Liver Physiol 2007; 292:G1474-82. [PMID: 17322063 DOI: 10.1152/ajpgi.00562.2006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) increases pancreatic insulin secretion via a direct action on pancreatic beta-cells. A high density of GLP-1-containing neurons and receptors is also present in brain stem vagal circuits; therefore, the aims of the present study were to investigate 1) whether identified pancreas-projecting neurons of the dorsal motor nucleus of the vagus (DMV) respond to exogenously applied GLP-1, 2) the mechanism(s) of action of GLP-1, and 3) whether the GLP-1-responsive neurons (putative modulators of endocrine secretion) could be distinguished from DMV neurons responsive to peptides that modulate pancreatic exocrine secretion, specifically pancreatic polypeptide (PP). Whole cell recordings were made from identified pancreas-projecting DMV neurons. Perfusion with GLP-1 induced a concentration-dependent depolarization in approximately 50% of pancreas-projecting DMV neurons. The GLP-1 effects were mimicked by exendin-4 and antagonized by exendin-(9-39). In approximately 60% of the responsive neurons, the GLP-1-induced depolarization was reduced by tetrodotoxin (1 microM), suggesting both pre- and postsynaptic sites of action. Indeed, the GLP-1 effects were mediated by actions on potassium currents, GABA-induced currents, or both. Importantly, neurons excited by GLP-1 were unresponsive to PP and vice versa. These data indicate that 1) GLP-1 may act on DMV neurons to control pancreatic endocrine secretion, 2) the effects of GLP-1 on pancreas-projecting DMV neurons are mediated both via a direct excitation of their membrane as well as via an effect on local circuits, and 3) the GLP-1-responsive neurons (i.e., putative endocrine secretion-controlling neurons) could be distinguished from neurons responsive to PP (i.e., putative exocrine secretion-controlling neurons).
Collapse
|
84
|
Hatton-Ellis E, Ainsworth C, Sushama Y, Wan S, VijayRaghavan K, Skaer H. Genetic regulation of patterned tubular branching in Drosophila. Proc Natl Acad Sci U S A 2007; 104:169-74. [PMID: 17190812 PMCID: PMC1765429 DOI: 10.1073/pnas.0606933104] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Indexed: 11/18/2022] Open
Abstract
A common theme in organogenesis is the branching of epithelial tubes, for example in the lung, liver, or kidney. The later morphogenesis of these branched epithelia dictates the final form and function of the mature tissue. Epithelial branching requires the specification of branch cells, the eversion process itself, and, frequently, patterned morphogenesis to produce branches of specific shape and orientation. Using the branching of renal tubule primordia from the hindgut in Drosophila, we show that these aspects are coordinately regulated. Cell specification depends on Wnt signaling along the tubular gut and results in the spatially restricted coexpression of two transcription factors, Krüppel and Cut, in the hindgut, whose activity drives cells toward renal tubule fate. Significantly, these transcription factors also confer the competence to respond to a second signal; TGF-beta induces branching to form the four renal tubule buds. Differential activation of the TGF-beta pathway also patterns the tubules, resulting in the asymmetry in size and positioning that is characteristic of the two tubule pairs. High levels of TGF-beta promote the expression of Dorsocross1-3 and anterior tubule growth, whereas low levels allow the expression of the transcriptional repressor, Brinker, and thus promote posterior tubule identity. We show that patterning of the tubule primordium into two distinct pairs is critical for the eversion of tubule branches, as well as for their asymmetric morphogenesis.
Collapse
|
85
|
Ng CSH, Lee TW, Wan S, Yim APC. Video assisted thoracic surgery in the management of spontaneous pneumothorax: the current status. Postgrad Med J 2006; 82:179-85. [PMID: 16517799 PMCID: PMC2563704 DOI: 10.1136/pgmj.2005.038398] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Over the past decade, video assisted thoracic surgery (VATS) has changed the way spontaneous pneumothorax (SP) is managed. Benefits of VATS include less postoperative pain, shorter hospital stay, and attenuated postoperative inflammatory response are evident compared with open thoracic procedures. Furthermore, the increasing acceptance by patients and referring physicians is testament to its success. Recent studies and the authors decade of experience in management of SP by VATS show that it is quick, safe, and effective, with recurrence rates generally comparable to open procedures, with some exceptions. However, selecting the correct procedure and patient, as well as knowing the limitations of the surgeons and techniques are paramount for success. Even to this day, there are considerable variations in the treatment of SP and large scale controlled studies are needed to better define timing of surgery and the role of the different procedures in the treatment and prevention of SP.
Collapse
|
86
|
Ng CSH, Wan S, Underwood MJ, Yim APC. Video-assisted thoracic surgery and extramedullary haematopoiesis. Eur Respir J 2006; 28:255-6. [PMID: 16816355 DOI: 10.1183/09031936.06.00045406] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
87
|
Wan S, Hua Y, Keep RF, Hoff JT, Xi G. Deferoxamine reduces CSF free iron levels following intracerebral hemorrhage. ACTA NEUROCHIRURGICA. SUPPLEMENT 2006; 96:199-202. [PMID: 16671454 DOI: 10.1007/3-211-30714-1_43] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Iron overload occurs in brain after intracerebral hemorrhage (ICH). Deferoxamine, an iron chelator, attenuates perihematomal edema and oxidative stress in brain after ICH. We investigated the effects of deferoxamine on cerebrospinal fluid (CSF) free iron and brain total iron following ICH. Rats received an infusion of 100-microL autologous whole blood into the right basal ganglia, then were treated with either deferoxamine (100 mg/kg, i.p., administered 2 hours after ICH and then at 12-hour intervals for up to 7 days) or vehicle. The rats were killed at different time points from 1 to 28 days for measurement of free and total iron. Behavioral tests were also performed. Free iron levels in normal rat CSF were very low (1.1 +/- 0.4 micromol). After ICH, CSF free iron levels were increased at all time points. Levels of brain total iron were also increased after ICH (p < 0.05). Deferoxamine given 2 hours after ICH reduced free iron in CSF at all time points. Deferoxamine also reduced ICH-induced neurological deficits (p < 0.05), but did not reduce total brain iron. In conclusion, CSF free iron levels increase after ICH and do not clear for at least 28 days. Deferoxamine reduces free iron levels and improves functional outcome in the rat, indicating that it may be a potential therapeutic agent for ICH patients.
Collapse
|
88
|
Glynne-Jones R, Meadows H, Wan S. EXTRA Trial-Evaluation of capecitabine treatment with radiotherapy (RT) in anal cancer: Preliminary results on toxicity and outcome. J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.14085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
14085 Background: Phase III trials have shown RT + 5-Fluorouracil (5-FU) + mitomycinC (MMC) as the standard treatment for patients with epidermoid anal carcinoma. The objective of this trial is to determine if capecitabine in combination with MMC has a similar outcome in terms of complete response (CR) rate and toxicity to a 5-day infusion of 5-FU. Capecitabine is a rational alternative to 5-FU as these cancers express high levels of thymidine phosphoralase. Methods: Main eligibility criteria are histologically proven anal carcinoma (epidermoid, squamous, basaloid), fit to receive capecitabine and MMC and ineligible for the ongoing phase III UK trial, ACT II. Exclusion criteria include complete local excision, prior chemoradiation, uncontrolled cardiovascular disease and known HIV+ve. All patients receive: 50.4Gy in 28F(RT) and capecitabine 1650mg/m2/day on each RT treatment day (M-F) over 6 weeks. In addition patients receive MMC 12mg/m2, day 1 only. Assessment of response is by CT scan at 4 wks post chemoradiation. Results: To date 18/30 patients have been registered. Pre-treatment characteristics are: median age 59 yrs (44–85); 7 male, 11 female; 13 Canal, 5 Margin; 5T1, 4T2, 6T3, 2T4, 1Tx; 4N+ve, 13N-ve, 1Nx. Data on 14 evaluable pts are presented here. RT compliance: 12 pts completed planned treatment, treatment was interrupted in 2 cases (chest pain 1; machine breakdown 1). Chemotherapy compliance: 10 pts completed protocol treatment, in 3 pts chemotherapy was affected due to toxicity (1 dose reduced, 2 stopped early 1 due to chest pain and 1 due to grade 3 skin and diarrhoea). One patient decided to stop treatment. Grade 3 toxicity was reported in 2 pts during treatment: dyspnoea 1, diarrhoea 1. Four weeks post chemoradition, 10 had CR, 3 had partial response and 1 pt was not assessable. Thirteen pts are alive and disease free at a median follow-up of 6 months (range 1 -13). One pt has relapsed in an inguinal node 9 months after the end of treatment following a previous CR. Conclusions: This early information suggests that this regimen can be given without interruption and with acceptable toxicity. The early response data is encouraging and the trial aims to reach target accrual by Summer 2006. Educational grant provided by Roche pharmaceuticals. [Table: see text]
Collapse
|
89
|
|
90
|
Guan P, Davies M, Taylor D, Wan S, McSparron H, Hemsley S, Toseland C, Blythe M, Taylor P, Walshe V, Hattotuwagama C, Doytchinova I, Coveney P, Borrow P, Flower D. Computational Chemistry, Informatics, and the Discovery of Vaccines. Curr Comput Aided Drug Des 2005. [DOI: 10.2174/157340905774330282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
91
|
|
92
|
Abstract
The central role of lung ischaemia-reperfusion injury in pulmonary dysfunction after cardiac surgery, particularly thoracic organ transplantation, has been well recognised. Lung tissue necrosis after prolonged ischaemia is known to worsen lung function, which was believed to be due largely to adjacent tissue inflammation. Recent studies suggest that lung apoptosis following ischaemia-reperfusion could be equally important in the development of post-operative lung dysfunction. The current literature on the mechanism and pathways involved in pulmonary dysfunction and, in particular, its relationship with apoptosis after lung ischaemia-reperfusion is briefly reviewed here. A better understanding of lung apoptosis, as well as the upstream pathways, may help in the development of therapeutic strategies that could benefit patients undergoing cardiac and lung transplantation.
Collapse
|
93
|
Lee K, Fok M, Wan S, Shu C. Optically controlled Sagnac loop comb filter. OPTICS EXPRESS 2004; 12:6335-6340. [PMID: 19488280 DOI: 10.1364/opex.12.006335] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We propose a new type of dynamically tunable birefringence comb filter based on a semiconductor optical amplifier Sagnac loop interferometer. By optically modulating the birefringence of the amplifier, we demonstrate a tuning of the output wavelengths. The shift of wavelength increases monotonically with the power of the control light until saturation occurs. The tuning relation is independent of the comb spacing governed by the length and birefringence of the polarization maintaining fiber inside the loop. A tuning range up to 59% of the comb spacing has been achieved at 18.5 dBm input power.
Collapse
|
94
|
Ng CSH, Wan S, Yim APC. Paradigm shift in surgical approaches to spontaneous pneumothorax: VATS. Thorax 2004; 59:357; author reply 357. [PMID: 15047969 PMCID: PMC1763812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
|
95
|
Ng CSH, Wan S, Yim APC, Vale J. Idiopathic localised bladder amyloidosis: rare cause of haematuria. Int Urol Nephrol 2003; 34:55-8. [PMID: 12549640 DOI: 10.1023/a:1021302827755] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Idiopathic Localised Bladder Amyloidosis is a rare cause of haematuria and urinary tract symptoms. A review of the literature highlights the varied presentations and the appropriate investigations for this condition, with emphasise on the exclusion of a secondary cause. In addition, the range of treatment options is fully discussed. Our report on a 65-year old gentleman illustrates that a high index of suspicion is required for its diagnosis. Furthermore, conservative management can be an effective strategy in selected patients.
Collapse
|
96
|
Ng CSH, Arifi AA, Wan IYP, Chan CSY, Ho AMH, Yim APC, Wan S. Maintaining Ventilation During Cardiopulmonary Bypass Attenuates Polymorphonuclear Cell Activation and May Reduce Pulmonary Polymorphonuclear Cell Sequestration. J Card Surg 2003. [DOI: 10.1046/j.1540-8191.2002.101435.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
97
|
Bulbulia RA, Smith FCT, Lamont PM, Baird RN, Angelini GD, Jeremy JY, Yim A, Wan S. An endothelin type A receptor antagonist inhibits neointimal hyperplasia and increases luminal area in porcine vein grafts. Br J Surg 2002. [DOI: 10.1046/j.1365-2168.2001.01757-13.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Background
Neointimal hyperplasia is responsible for the majority of cases of vein graft failure. To date, no pharmacological intervention has proved successful in preventing this process in humans. Endothelin (ET) 1 is a potent vasoconstrictor and promotes the proliferation of vascular smooth muscle cells in vitro. The authors have shown previously that porcine vein grafts contain high levels of ET-1 and ET type A (ETA) receptor subtypes. The aim was to investigate the effect of an ETA receptor antagonist, BSF 302146, on luminal area and graft wall dimensions in a porcine model of arteriovenous bypass grafting.
Methods
Bilateral saphenous vein–carotid artery interposition grafting was performed in two groups of Large White pigs (26–32 kg; n = 5 per group). BSF 302146 (10 mg kg−1 day−1) was administered orally to animals in group 1; group 2 animals acted as controls. After 4 weeks the grafts were explanted and pressure-fixed ex vivo. Histological sections were obtained and graft dimensions assessed by means of computer-aided planimetry.
Results
BSF 302146 significantly reduced both neointimal hyperplasia and medial thickening, and increased luminal area by 77 per cent.
Conclusion
The ETA receptor antagonist BSF 302146 inhibits neointimal hyperplasia and increases luminal area in a porcine model of saphenous vein bypass grafting.
Collapse
|
98
|
Dashwood MR, Angelini GD, Wan S, Yim A, Mehta D, Izzat MB, Jeremy JY. Does external stenting reduce porcine vein-graft occlusion via an action on vascular nerves? J Card Surg 2002; 17:556-60. [PMID: 12643468 DOI: 10.1046/j.1540-8191.2002.01012.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Neural reorganization occurs in porcine vein grafts and placement of an external stent reduces graft occlusion. AIM OF THE STUDY To determine the effect of external stenting on the innervation of porcine vein grafts. METHODS Saphenous vein into carotid artery grafting (with and without external stents) was performed in 16 pigs. After one and six months, grafts were removed, nerves were counted, and neointima was assessed. RESULTS In vein graft compared to ungrafted vein, there was a significant (p < 0.05) decrease in medial perivascular nerves, but a dramatic increase in paravascular nerves in the adventitia (p < 0.05). In stented vein grafts there was also a reduction of perivascular nerves and the paravascular nerve proliferation observed in vein grafts at one month was inhibited (p < 0.05). Neointima formation and the appearance of large paravascular nerve bundles in the adventitia of vein grafts were abolished by external stenting. CONCLUSIONS Neural reorganization plays a role in vein-graft failure, possibly through the local release of mitogens; the prevention of this reorganization contributes to the inhibitory effect of the external stent on neointima formation.
Collapse
|
99
|
Ng CSH, Wan S, Lee TW, Sihoe ADL, Wan IYP, Arifi AA, Yim APC. Video-assisted thoracic surgery for mediastinal extramedullary haematopoiesis. Ann R Coll Surg Engl 2002; 84:161-3. [PMID: 12092864 PMCID: PMC2503808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
Abstract
Extramedullary haematopoiesis is a rare cause of an intrathoracic mass. We report a case of posterior mediastinal extramedullary haematopoietic mass in a 50-year-old man who presented with non-specific symptoms and a paravertebral mass on chest X-ray. Diagnosis was achieved by using video-assisted thoracic surgery.
Collapse
|
100
|
Luo Y, Wan S, Hui D, Wallace LL. Acclimatization of soil respiration to warming in a tall grass prairie. Nature 2001; 413:622-5. [PMID: 11675783 DOI: 10.1038/35098065] [Citation(s) in RCA: 370] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The latest report by the Intergovernmental Panel on Climate Change (IPCC) predicts a 1.4-5.8 degrees C average increase in the global surface temperature over the period 1990 to 2100 (ref. 1). These estimates of future warming are greater than earlier projections, which is partly due to incorporation of a positive feedback. This feedback results from further release of greenhouse gases from terrestrial ecosystems in response to climatic warming. The feedback mechanism is usually based on the assumption that observed sensitivity of soil respiration to temperature under current climate conditions would hold in a warmer climate. However, this assumption has not been carefully examined. We have therefore conducted an experiment in a tall grass prairie ecosystem in the US Great Plains to study the response of soil respiration (the sum of root and heterotrophic respiration) to artificial warming of about 2 degrees C. Our observations indicate that the temperature sensitivity of soil respiration decreases--or acclimatizes--under warming and that the acclimatization is greater at high temperatures. This acclimatization of soil respiration to warming may therefore weaken the positive feedback between the terrestrial carbon cycle and climate.
Collapse
|