276
|
Dong X, Shum P, Ngo N, Chan C, Ng J, Zhao C. A largely tunable CFBG-based dispersion compensator with fixed center wavelength. OPTICS EXPRESS 2003; 11:2970-2974. [PMID: 19471417 DOI: 10.1364/oe.11.002970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A largely tunable chirped fiber Bragg grating (CFBG)-based dispersion compensator with fixed center wavelength is demonstrated. Tunable dispersion ranging from 178 to 2126 ps/nm, corresponding to a large range of 3-db bandwidth from 0.42 to 5.04 nm, is realized by using a 10 cm-long CFBG with an original bandwidth of 1.61 nm. The variation in center wavelength is less than 0.2 nm.
Collapse
|
277
|
Mercado MA, Chan C, Orozco H, Tielve M, Hinojosa CA. Acute bile duct injury. The need for a high repair. Surg Endosc 2003; 17:1351-5. [PMID: 12811664 DOI: 10.1007/s00464-002-8705-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2003] [Accepted: 02/21/2003] [Indexed: 10/26/2022]
Abstract
BACKGROUND An immediate repair is considered optimal in acute biliary duct injuries; however, it may prove to be a challenge, because such repairs are usually performed on small ducts whose viability cannot always be determined. METHODS We performed a retrospective review of the charts of patients with acute bile duct injury who underwent repair at a tertiary care academic university hospital. A total of 204 patients with acute bile duct injury were seen between 1989 and 2002. Of these, 30 were repaired within minutes to hours after the injury. These patients were divided into two groups. Group I patients had a Roux-en-Y hepatojejunostomy below the hepatic junction; Group II patients had a Roux-en-Y hepatojejunostomy at the junction level. We then performed a long-term evaluation of anastomosis function in these patients, using clinical, radiological, and laboratory. RESULTS Twenty-eight injuries were secondary to a laparoscopy; the other two resulted from open cholecystectomies. All of the patients suffered complex injuries with complete section of the duct and substance loss (Strasberg E). There were 12 patients in group I and 18 in group II. Three cases in group I (25%) and one in group II (5%) developed anastomosis dysfunction. Mean follow-up was 56 months (range, 12-80) in group I and 52 months (range, 10-76) in group II. Two cases in group I (16%) and none in group II (0) required reoperation (p < 0.05). CONCLUSIONS In the acute setting, complex lesions should be treated with a high bilioenteric anastomosis (at the junction level) in the first attempt at repair. Lower-level anastomoses are associated with a higher dysfunction rate and the need for radiological manipulation and reoperation. Also, stenosis of the anastomosis secondary to undetected duct ischemia in the acute repair is more frequent in low bilioenteric anastomoses.
Collapse
|
278
|
Chan C, Fryer J, Herkes G, Prelog K, Harrington T. Fatal brain stem event complicating acute pancreatitis. J Clin Neurosci 2003; 10:351-8. [PMID: 12763345 DOI: 10.1016/s0967-5868(03)00015-8] [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: 10/27/2022]
Abstract
Acute pancreatitis, developing in a patient with chronic renal failure, was complicated by a fatal neurological illness during which MRI showed pontine and extrapontine changes consistent with pontine and extrapontine myelinolysis. At post mortem, acute pancreatitis was confirmed but the neuropathological findings were more in keeping with an unusual presentation of acute haemorrhagic leucoencephalitis, perhaps even representing a form of 'pancreatic encephalopathy'. Although the development of CT and MRI scanning has greatly increased the resolution of neuroimaging and facilitated diagnosis during life, the value of autopsy examination is confirmed in cases such as this. Sometimes the findings may raise more questions than may have been answered - this too is an important function!
Collapse
|
279
|
Soon D, Yeo K, Lim M, Chan C, Wise S. CYP3A activity as determined by midazolam PK, is similar between Chinese, Indians and Caucasians before and after rifampicin treatment but not as determined by 6B-OH cortisol formation. Clin Pharmacol Ther 2003. [DOI: 10.1016/s0009-9236(03)90428-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
280
|
Wang CY, Chiu CL, Har KO, Chan C, Rahman ZAA. A comparative study of sevoflurane sedation with nitrous oxide sedation for dental surgery. Int J Oral Maxillofac Surg 2002; 31:506-10. [PMID: 12418566 DOI: 10.1054/ijom.2002.0293] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study compares the use of inhalation sedation using sevoflurane (group S) with inhalation sedation using nitrous oxide (group N) in patients undergoing bilateral extraction of third molar teeth under local anaesthesia. The study was designed as a cross-over study. Seventeen ASA I, day surgery patients were studied. Patients were randomly allocated to receive either 8 l/min 50% nitrous oxide in oxygen (group N) or same flow of 1% sevoflurane (group S) for the first procedure. Each patient then had the alternate method of sedation for the second procedure. There were no significant differences between the methods in patient co-operation and surgeon's satisfaction with sedation. Psychomotor tests were comparable in both groups. The patients were significantly more sedated in the group S compared to group N (P=0.004). Significantly more patients complained of an unpleasant odour group S (P<0.01) but none withdrew from the study for this reason. No adverse cardiorespiratory effects resulted from sevoflurane or nitrous oxide sedation. Both methods gave good amnesia during the procedure. There was high acceptance of both methods and the patients rated the technique as equally satisfactory. We conclude that inhalation sedation with sevoflurane is a suitable alternative method to nitrous oxide sedation.
Collapse
|
281
|
Crankshaw DP, Chan C, Leslie K, Bjorksten AR. Remifentanil concentration during target-controlled infusion of propofol. Anaesth Intensive Care 2002; 30:578-83. [PMID: 12413255 DOI: 10.1177/0310057x0203000505] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
After institutional approval and with written informed consent, eight surgical patients were infused intravenously with remifentanil at 250 ngkg lean body mass (LBM)(-1) x min(-1) for 30 min. Cardiovascular and respiratory parameters were recorded and arterial blood samples were taken at regular intervals. In each patient, the same protocol was repeated 40 min later during propofol infused to a target concentration of 3.0 microg x ml(-1). Blood concentrations of remifentanil and propofol were assayed using capillary gas chromatography and high performance liquid chromatography techniques respectively. The number of subjects enrolled was determined by testing the successive areas under the remifentanil time-concentration curve (AUC) for significant difference or non-difference using sequential analysis. The median measured propofol concentration was 3.5 (range: 2.6-4.5) microg x ml(-1) which did not change significantly during the second remifentanil infusion. The median AUC during propofol infusion was greater than control in all subjects, although there was considerable variation of 94.4 (64.3-129.6) versus 64.6 (34.8-126.9) ng x ml(-1) x min; P=0.008, n=8. After 30 min, there was no significant difference in remifentanil concentration during propofol infusion when compared with remifentanil alone of 4.6 (3.2-5.7) versus 3.8 (1.6-4.9) ng x ml(-1); P=0.73, n=8. Co-administration of propofol and remifentanil may result in greater remifentanil concentrations than when remifentanil is infused alone.
Collapse
|
282
|
Chan C, Ho SC, Chan SG, Yip YB, Wong FC, Cheng F. Factors affecting uptake of cervical and breast cancer screening among perimenopausal women in Hong Kong. Hong Kong Med J 2002; 8:334-41. [PMID: 12376710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
Abstract
OBJECTIVES To identify factors affecting cervical and breast cancer screening attendance among women aged 44 to 55 years by comparing self-reported uptake of cervical smear and clinical breast examination between patients and a population sample. DESIGN AND SETTING Telephone survey and audit of clinic records to confirm patients' self-report. PARTICIPANTS Two thousand and sixty-seven women identified through random telephone dialling from the residence directory and 319 patients ever-registered at a family practice teaching clinic. MAIN OUTCOME MEASURES Uptake of cervical smear and clinical breast examination. RESULTS The proportion of women undergoing cervical smear tests and clinical breast examination in the previous 12 months were 35.4% and 22.6%, respectively, for randomly selected women, while the figures were 47.2% and 50.6%, respectively, for patients. Record audit confirmed high rates of screening for patients according to evidence-based protocols (85.1% had had a cervical smear within 3 years). For women in the random sample (mean age, 48.9 years; standard deviation, 3.3 years), those who were older, postmenopausal, not receiving hormone therapy, educated to primary level, and with no chronic diseases were least likely to have had screening. For clinic patients (mean age, 47.9 years; standard deviation, 2.8 years), lower education level was the only variable associated with no recent smears. CONCLUSIONS Healthy perimenopausal and postmenopausal women in the community with lower educational level and not receiving hormone therapy were more likely to be underscreened. Attendance of 44- to 55-year-old women at a family medicine clinic that actively promotes preventive medicine was associated with high screening uptake.
Collapse
|
283
|
Hsu LF, Mak KH, Lau KW, Sim LL, Chan C, Koh TH, Chuah SC, Kam R, Ding ZP, Teo WS, Lim YL. Clinical outcomes of patients with diabetes mellitus and acute myocardial infarction treated with primary angioplasty or fibrinolysis. Heart 2002; 88:260-5. [PMID: 12181218 PMCID: PMC1767339 DOI: 10.1136/heart.88.3.260] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE To compare the early and late outcomes of primary percutaneous transluminal coronary angioplasty (PTCA) with fibrinolytic treatment among diabetic patients with acute myocardial infarction (AMI). DESIGN Retrospective observational study with data obtained from prospective registries. SETTING Tertiary cardiovascular institution with 24 hour acute interventional facilities. PATIENTS 202 consecutive diabetic patients with AMI receiving reperfusion treatment within six hours of symptom onset. INTERVENTIONS Fibrinolytic treatment was administered to 99 patients, and 103 patients underwent primary PTCA. Most patients undergoing PTCA received adjunctive stenting (94.2%) and glycoprotein IIb/IIIa inhibition (63.1%). MAIN OUTCOME MEASURES Death, non-fatal reinfarction, and target vessel revascularisation at 30 days and one year were assessed. RESULTS Baseline characteristics were similar in these two treatment groups except that the proportion of patients with Killip class III or IV was considerably higher in those treated with PTCA (15.5% v 6.1%, p = 0.03) and time to treatment was significantly longer (103.7 v 68.0 minutes, p < 0.001). Among those treated with PTCA, the rates for in-hospital recurrent ischaemia (5.8% v 17.2%, p = 0.011) and target vessel revascularisation at one year (19.4% v 36.4%, p = 0.007) were lower. Death or reinfarction at one year was also reduced among those treated with PTCA (17.5% v 31.3%, p = 0.02), with an adjusted relative risk of 0.29 (95% confidence interval 0.15 to 0.57) compared with fibrinolysis. CONCLUSION Among diabetic patients with AMI, primary PTCA was associated with reduced early and late adverse events compared with fibrinolytic treatment.
Collapse
|
284
|
Bjorksten AR, Chan C, Crankshaw DP. Determination of remifentanil in human blood by capillary gas chromatography with nitrogen-selective detection. J Chromatogr B Analyt Technol Biomed Life Sci 2002; 775:97-101. [PMID: 12101065 DOI: 10.1016/s1570-0232(02)00178-2] [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: 11/27/2022]
Abstract
A validated method for the determination of remifentanil in human blood, applicable to all therapeutic concentrations, using capillary GC with nitrogen-specific detection and fentanyl as the internal standard has been developed. Citrated whole blood samples were extracted into 1-chlorobutane following precipitation of proteins with methanol. The drugs were back extracted into 10 mM HCl and re-extracted into methanol-1-chlorobutane. The extracts were reconstituted in methanol and injected onto a 25-m BPX-5 column. The lower limit of quantitation was 0.2 ng/ml with within- and between-day coefficients of variation of less than 15%.
Collapse
|
285
|
Ong YK, Goh KYC, Chan C. Bifrontal decompressive craniectomy for acute subdural empyema. Childs Nerv Syst 2002; 18:340-3; discussion 344. [PMID: 12172943 DOI: 10.1007/s00381-002-0597-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2001] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Subdural empyema is an uncommon but serious complication of sinusitis. Despite the use of advanced imaging facilities, modern antibiotic therapy and aggressive neurosurgical protocols, this condition still carries significant morbidity and mortality. CASE REPORT We report an unusual case of sinusitis-associated acute subdural empyema in a 13-year-old patient, presenting in a catastrophic manner with acutely raised intracranial pressure. Emergency bifrontal decompressive craniectomy was necessary both to reduce the intracranial pressure and to drain the subdural empyema. RESULTS The full range of intracranial complications subsequently occurred, including brain abscesses, recurrent subdural empyema and ventriculitis. Despite this, the patient's outcome was good, with minimal intellectual deficits. CONCLUSION In cases of severe intracranial infection, we therefore advocate an aggressive surgical approach coupled with appropriate antibiotics to ensure a good outcome.
Collapse
|
286
|
Chan C, Yin H, McKie JH, Fairlamb AH, Douglas KT. Peptoid inhibition of trypanothione reductase as a potential antitrypanosomal and antileishmanial drug lead. Amino Acids 2002; 22:297-308. [PMID: 12107758 DOI: 10.1007/s007260200016] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
One route to the design of lead compounds for rational drug design approaches to developing drugs against trypanosomiasis, Chagas' disease and leishmaniasis is to develop novel inhibitors of the parasite-specific enzyme trypanothione reductase. A lead inhibitor based on a peptoid structure was designed in the present study based on the known strong competitive inhibition of trypanothione reductase by N-benzoyl-Leu-Arg-Arg-beta-naphthylamide and N-benzyloxycarbonyl-Ala-Arg-Arg-4-methoxy- beta-naphthylamide. In the target peptoid the arginyl residues were replaced by alkylimidazolium units and the benzyloxycarbonyl group by the benzylaminocarbonyl function. The peptoid was synthesised using t-butoxycarbonyl protection chemistry and couplings were activated by 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate. The resulting peptoid was shown to be a competitive inhibitor of recombinant trypanothione reductase from Trypanosoma cruzi with a K(i) value of 179 microM and with only weak inhibition of human erythrocyte glutathione reductase (the inhibition of glutathione reductase was at least 291-fold weaker than of trypanothione reductase).
Collapse
|
287
|
Trost BM, Lautens M, Chan C, Jebaratnam DJ, Mueller T. Annulation via alkylation-Alder ene cyclizations. Palladium-catalyzed cycloisomerization of 1,6-enynes. J Am Chem Soc 2002. [DOI: 10.1021/ja00002a036] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
288
|
Evans DF, Chan C, Lamartine BC. The effect of charge upon mobility. A critical examination of the Zwanzig equation. J Am Chem Soc 2002. [DOI: 10.1021/ja00462a004] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
289
|
Kumar K, Thomas J, Chan C. Cosmesis in neurosurgery: is the bald head necessary to avoid postoperative infection? ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2002; 31:150-4. [PMID: 11957549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
AIM The aims of this study were to prospectively investigate the incidence of postoperative wound infection following elective cranial surgery, when scalp hair removal was limited to the line of the incision, and to see if there was an increased risk of infection. MATERIALS AND METHODS This is an observational study of 57 consecutive adult elective cases operated upon without head shave (between July 1998 and December 1998). The method of scalp preparation is described. RESULTS During the follow-up period, there was 1 case (1.75%) of postoperative wound infection. This was compared with retrospective data, and was not found to be statistically significant. DISCUSSION In a review of earlier studies and a search into the history of aseptic surgery, no scientific ground for the practice of shaving was found. We suggest that there is no advantage in shaving patients in terms of reducing wound infection rates.
Collapse
|
290
|
Chan C, Thompson I, Robinson P, Wilson J, Hench L. Evaluation of Bioglass/dextran composite as a bone graft substitute. Int J Oral Maxillofac Surg 2002; 31:73-7. [PMID: 11936404 DOI: 10.1054/ijom.2001.0143] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Allogenic and alloplastic bone graft substitutes serve either as bioinert or bioactive osteoconductors. Bioglass is a bioactive osteoconductor and also shows osteoproductive effects due to its high level of bioactivity. However, the material lacks some cohesiveness when used in augmenting certain bony surfaces, i.e. large or pleomorphic defects. The addition of medium molecular weight dextran modifies the particulate to a putty consistency and improves the handling characteristics. The objective of this study is to evaluate the influence of dextran upon the bioactive properties of Bioglass. Standardized bony defects in the lateral femoral condyles in adult New Zealand white rabbits were filled with one of five material groups: (1) autogenous bone; (2) Bioglass particulate; (3) Bioglass particulate mixed with dextran to a putty-like consistency; (4) a mixture of Bioglass and autogenous bone; (5) a mixture of Bioglass putty with autogenous bone. Postoperative healing was observed after periods of 2 days, 1, 2, 3, 6 and 12 weeks. Results showed no evidence of toxicity in the dextran-containing materials, and defects in all test groups showed 100% bony ingrowth within 6 weeks. The addition of medium molecular weight dextran did not appear to alter the bioactive properties of Bioglass and had no adverse influence upon the ingrowth of bone into the defect sites.
Collapse
|
291
|
Lavrentiadou SN, Chan C, Kawcak T, Ravid T, Tsaba A, van der Vliet A, Rasooly R, Goldkorn T. Ceramide-mediated apoptosis in lung epithelial cells is regulated by glutathione. Am J Respir Cell Mol Biol 2001; 25:676-84. [PMID: 11726392 PMCID: PMC4370277 DOI: 10.1165/ajrcmb.25.6.4321] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Reactive oxygen species (ROS) are mediators of lung injury, and glutathione (GSH) is the major nonprotein antioxidant that protects the cell from oxidative stress. We have recently shown that H(2)O(2) induces ceramide-mediated apoptosis in human lung epithelial cells. We hypothesized that ROS-mediated depletion of GSH plays a regulatory role in ceramide generation, and thus in the induction of apoptosis. Our present studies demonstrate that GSH at physiologic concentrations (1 to 10 mM) inhibits ceramide production in a time- and dose-dependent manner in A549 human alveolar epithelial cells. On the other hand, buthionine-sulfoximine-mediated depletion of intracellular GSH induces elevation of ceramide levels and apoptosis. In addition, GSH blocks H(2)O(2)-mediated induction of intracellular ceramide generation and apoptosis. These effects were not mimicked by oxidized GSH (GSSG) or other thiol antioxidants, such as dithiothreitol and 2-mercaptoethanol. Moreover, increase of intracellular H(2)O(2), mediated by inhibition of catalase by aminotriazole, also induces ceramide generation and apoptosis. These effects were blocked by N-acetylcysteine. Our results suggest that GSH depletion may be the link between oxidative stress and ceramide-mediated apoptosis in the lung.
Collapse
|
292
|
McKie JH, Garforth J, Jaouhari R, Chan C, Yin H, Besheya T, Fairlamb AH, Douglas KT. Specific peptide inhibitors of trypanothione reductase with backbone structures unrelated to that of substrate: potential rational drug design lead frameworks. Amino Acids 2001; 20:145-53. [PMID: 11332449 DOI: 10.1007/s007260170055] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
By introducing cationic charge sites novel peptide lead inhibitor structures for trypanothione reductase have been designed using molecular modelling methods. The inhibitors showed reversible, linear competitive inhibition and the strongest peptide inhibitor to date was found to be N-benzyloxycarbonyl-Ala-Arg-Arg-4-methoxy-beta-naphthylamide with a Ki value of 2.4 microM and a selectivity for parasitic enzyme (trypanothione reductase) over the host enzyme (human glutathione reductase) of over 3 orders of magnitude.
Collapse
|
293
|
McDermott MM, Greenland P, Liu K, Guralnik JM, Criqui MH, Dolan NC, Chan C, Celic L, Pearce WH, Schneider JR, Sharma L, Clark E, Gibson D, Martin GJ. Leg symptoms in peripheral arterial disease: associated clinical characteristics and functional impairment. JAMA 2001; 286:1599-606. [PMID: 11585483 DOI: 10.1001/jama.286.13.1599] [Citation(s) in RCA: 574] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Persons with lower-extremity peripheral arterial disease (PAD) are often asymptomatic or have leg symptoms other than intermittent claudication (IC). OBJECTIVE To identify clinical characteristics and functional limitations associated with a broad range of leg symptoms identified among patients with PAD. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study of 460 men and women with PAD and 130 without PAD, who were identified consecutively, conducted between October 1998 and January 2000 at 3 Chicago-area medical centers. MAIN OUTCOME MEASURES Ankle-brachial index score of less than 0.90; scores from 6-minute walk, accelerometer-measured physical activity over 7 days, repeated chair raises, standing balance (full tandem stand), 4-m walking velocity, San Diego claudication questionnaire, Geriatric Depression Score Short-Form, and the Walking Impairment Questionnaire. RESULTS All groups with PAD had poorer functioning than participants without PAD. The following values are for patients without IC vs those with IC. Participants in the group with leg pain on exertion and rest (n = 88) had a higher (poorer) score for neuropathy (5.6 vs 3.5; P<.001), prevalence of diabetes mellitus (48.9% vs 26.7%; P<.001), and spinal stenosis (20.8% vs 7.2%; P =.002). The atypical exertional leg pain/carry on group (exertional leg pain other than IC associated with walking through leg pain [n = 41]) and the atypical exertional leg pain/stop group (exertional leg pain other than IC that causes one to stop walking [n = 90]) had better functioning than the IC group. The group without exertional leg pain/inactive (no exertional leg pain in individual who walks </=6 blocks per week [n = 28]) and the leg pain on exertion and rest group had poorer functioning than those with IC. Adjusting for age, sex, race, and comorbidities and compared with IC, participants with atypical exertional leg pain/carry on achieved a greater distance on the 6-minute walk (404.3 vs 328.5 m; P<.001) and were less likely to stop during the 6-minute walk (6.8% vs 36%; P =.002). The group with pain on exertion and rest had a slower time for completing 5 chair raises (13.5 vs 11.9 seconds; P =.009), completed the tandem stand less frequently (37.5% vs 60.0%; P =.004), and had a slower 4-m walking velocity (0.80 vs 0.90 m/s; P<.001). CONCLUSIONS There is a wide range of leg symptoms in persons with PAD beyond that of classic IC. Comorbid disease may contribute to these symptoms in PAD. Functional impairments are found in every PAD symptom group, and the degree of functional limitation varies depending on the type of leg symptom.
Collapse
|
294
|
Aungst RA, Chan C, Funk RL. Total synthesis of the sesquiterpene (+/-)-illudin C via an intramolecular nitrile oxide cycloaddition. Org Lett 2001; 3:2611-3. [PMID: 11483073 DOI: 10.1021/ol016314o] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] A convergent total synthesis of illudin C is described. The tricyclic ring system of the natural product was quickly assembled from cyclopropane and cyclopentene precursors via a novel oxime dianion coupling reaction and a subsequent intramolecular nitrile oxide-olefin cycloaddition.
Collapse
|
295
|
Drees BL, Sundin B, Brazeau E, Caviston JP, Chen GC, Guo W, Kozminski KG, Lau MW, Moskow JJ, Tong A, Schenkman LR, McKenzie A, Brennwald P, Longtine M, Bi E, Chan C, Novick P, Boone C, Pringle JR, Davis TN, Fields S, Drubin DG. A protein interaction map for cell polarity development. J Cell Biol 2001; 154:549-71. [PMID: 11489916 PMCID: PMC2196425 DOI: 10.1083/jcb.200104057] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many genes required for cell polarity development in budding yeast have been identified and arranged into a functional hierarchy. Core elements of the hierarchy are widely conserved, underlying cell polarity development in diverse eukaryotes. To enumerate more fully the protein-protein interactions that mediate cell polarity development, and to uncover novel mechanisms that coordinate the numerous events involved, we carried out a large-scale two-hybrid experiment. 68 Gal4 DNA binding domain fusions of yeast proteins associated with the actin cytoskeleton, septins, the secretory apparatus, and Rho-type GTPases were used to screen an array of yeast transformants that express approximately 90% of the predicted Saccharomyces cerevisiae open reading frames as Gal4 activation domain fusions. 191 protein-protein interactions were detected, of which 128 had not been described previously. 44 interactions implicated 20 previously uncharacterized proteins in cell polarity development. Further insights into possible roles of 13 of these proteins were revealed by their multiple two-hybrid interactions and by subcellular localization. Included in the interaction network were associations of Cdc42 and Rho1 pathways with proteins involved in exocytosis, septin organization, actin assembly, microtubule organization, autophagy, cytokinesis, and cell wall synthesis. Other interactions suggested direct connections between Rho1- and Cdc42-regulated pathways; the secretory apparatus and regulators of polarity establishment; actin assembly and the morphogenesis checkpoint; and the exocytic and endocytic machinery. In total, a network of interactions that provide an integrated response of signaling proteins, the cytoskeleton, and organelles to the spatial cues that direct polarity development was revealed.
Collapse
|
296
|
Abstract
PURPOSE To discuss the autoimmune basis of melanoma-associated retinopathy (MAR) and its implications for management and prognosis. METHODS An unusual history of a woman with melanoma-associated retinopathy is presented in detail. A review of published reports and a summary of 19 reported cases of MAR provide a basis for discussion. RESULTS This case report and other published reports highlight a number of points regarding MAR including the male predominance, prolonged survival in several patients and lack of response to immunosuppression. CONCLUSIONS Melanoma-associated retinopathy may prolong the survival of patients with metastatic melanoma through the autoimmune response. Therefore, treatment of visual symptoms with immunosuppression needs to be considered carefully.
Collapse
|
297
|
Chan C, George AJ, Stark J. Cooperative enhancement of specificity in a lattice of T cell receptors. Proc Natl Acad Sci U S A 2001; 98:5758-63. [PMID: 11344310 PMCID: PMC33286 DOI: 10.1073/pnas.101113698] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2000] [Accepted: 03/07/2001] [Indexed: 11/18/2022] Open
Abstract
Two of the most important models to account for the specificity and sensitivity of the T cell receptor (TCR) are the kinetic proofreading and serial ligation models. However, although kinetic proofreading provides a means for individual TCRs to measure accurately the length of time they are engaged and signal appropriately, the stochastic nature of ligand dissociation means the kinetic proofreading model implies that at high concentrations the response of the cell will be relatively nonspecific. Recent ligand experiments have revealed the phenomenon of both negative and positive crosstalk among neighboring TCRs. By using a Monte Carlo simulation of a lattice of TCRs, we integrate receptor crosstalk with the kinetic proofreading and serial ligation models and discover that receptor cooperativity can enhance T cell specificity significantly at a very modest cost to the sensitivity of the response.
Collapse
|
298
|
Theng J, Chan C, Ling ML, Tan D. Microsporidial keratoconjunctivitis in a healthy contact lens wearer without human immunodeficiency virus infection. Ophthalmology 2001; 108:976-8. [PMID: 11320030 DOI: 10.1016/s0161-6420(01)00542-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To present a rare case of microsporidial keratoconjunctivitis in an otherwise healthy contact lens wearer without human immunodeficiency virus infection who responded to treatment with systemic albendazole and topical fumagillin. DESIGN Interventional case report. METHOD A cornea epithelial scraping from a man with unilateral keratoconjunctivitis previously treated with topical steroids was evaluated by modified trichome staining. MAIN OUTCOME MEASURES The patient was evaluated for his symptoms, visual acuity, clinical observations, and pathologic examination of corneal scrapes. RESULTS Modified trichome staining of an epithelial corneal scraping revealed pinkish to red organisms characteristic of microsporidia. Results of a human immunodeficiency virus (HIV) enzyme-linked immunosorbent assay test were negative. The symptoms of ocular discomfort and clinical signs of keratoconjunctivitis resolved after 2 months of treatment with albendazole and topical fumagillin. CONCLUSIONS Ocular infection with microsporidia, although classically occurring in patients with HIV infection, may occur rarely in healthy individuals, especially if previously treated with systemic immune suppression or topical steroids. Microsporidial keratoconjunctivitis should be considered in the differential diagnosis of a contact lens wearer with atypical multifocal diffuse epithelial keratitis.
Collapse
|
299
|
Ip M, Lyon DJ, Yung RW, Chan C, Cheng AF. Macrolide resistance in Streptococcus pneumoniae in Hong Kong. Antimicrob Agents Chemother 2001; 45:1578-80. [PMID: 11302833 PMCID: PMC90511 DOI: 10.1128/aac.45.5.1578-1580.2001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Erythromycin resistance rates among penicillin-susceptible Streptococcus pneumoniae were 38 and 92% among penicillin-intermediate and -resistant S. pneumoniae isolates from Hong Kong, respectively, and 27% (43 of 158) of the isolates showed the MLS(B) phenotype, and the majority carried the ermB gene; 73% (115 of 158) displayed the M phenotype, and all possessed the mef gene. The MLS(B) phenotype was predominant in penicillin-susceptible, macrolide-resistant isolates and in penicillin-nonsusceptible isolates of serotype 6B, whilst the M phenotype was predominant in penicillin-intermediate or -resistant isolates belonging to serotype 23F or 19F. Extensive spread of clones of drug-resistant pneumococci has led to the widespread presence of macrolide resistance in S. pneumoniae in Hong Kong.
Collapse
|
300
|
Teoh WH, Goh KY, Chan C. The role of early tracheostomy in critically ill neurosurgical patients. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2001; 30:234-8. [PMID: 11455734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
OBJECTIVE To determine the value of early tracheostomy (within 7 days) in ventilated neurosurgical patients. METHODS Retrospective review of intubated patients in the neurosurgical intensive care unit (NICU) who underwent elective open tracheostomies for prolonged ventilation. RESULTS Thirty patients over a 2-year period were analysed. There were 19 males and 11 females, mean age 53.9 +/- 18.1 years (range 14 to 89), and mean Glasgow Coma Scale (GCS) score on admission 7.1 +/- 3.8 (range 3 to 15). The underlying disease aetiology was cerebrovascular disease in 53% of patients, head trauma in 33% and tumour or infection in 13%. Tracheostomy was performed after a mean period of 8.5 +/- 3.5 days (range 2 to 18), with patients requiring ventilation for a mean duration of 13.5 +/- 6.3 days (range 3 to 31). Complications were minimal; 1 wound infection (3.3%) and 4 tube obstructions (13.3%). Patients who underwent elective early tracheostomy (Group 1 = within 7 days) had poorer GCS on admission (6.3 +/- 2.9 versus 7.7 +/- 4.3 in Group 2, P = 0.271). Tracheostomy was performed after a mean of 5.3 +/- 1.7 days in Group I vs. 10.6 +/- 2.7 days in Group 2. Group 1 patients had faster recovery from nosocomial pneumonia (12.3 +/- 6.2 versus 17.9 +/- 12.5 days, P = 0.168), shorter duration of ventilation (9.8 +/- 5.9 versus 16.0 +/- 5.4 days, P = 0.007), and reduced incidence of multibacterial tracheobronchial colonisation (42% versus 72%, P = 0.098). The most prevalent organisms were Acinetobacter baumanii (43.3%), Pseudomonas (40%), methicillin-resistant Staphylococcus aureus (MRSA) (33%), Klebsiella (30%) and Staphylococcus aureus (26.7%). CONCLUSION Early tracheostomy in selected neurosurgical patients with poor GCS scores was associated with reduced incidence of tracheobronchial colonisation by multiple pathogens, improvement in chest infections, and rapid weaning from ventilatory support.
Collapse
|