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Cheng HM, Park JH, Hernstadt D. Subacute combined degeneration of the spinal cord following recreational nitrous oxide use. BMJ Case Rep 2013; 2013:bcr-2012-008509. [PMID: 23476009 DOI: 10.1136/bcr-2012-008509] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
We describe a case of a young woman who developed myelopathy and peripheral neuropathy following 1 year of recreational nitrous oxide (N2O) use. She presented with uncomfortable tingling sensation in her feet and poor balance. Physical examination revealed mild weakness and hyper-reflexia in the lower limbs. Proprioception and vibration were absent in the lower limbs. Pinprick and light touch sensations were reduced below the sixth thoracic dermatome. A broad-based gait and a positive Romberg sign were noted. The level of vitamin B12 was low (76 pmol/l). T2-weighted MRI scans showed hyperintensity changes at the posterior column from the second to the fifth cervical vertebrae. She made a full recovery following injections of vitamin B12 and physiotherapy. This case discusses subacute combined degeneration of the spinal cord on a background of N2O abuse.
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Park JH, Lewis R, Cheng HM. An unusual cause of a lump in the parotid gland. BMJ Case Rep 2012; 2012:bcr-2012-007805. [PMID: 23220443 DOI: 10.1136/bcr-2012-007805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
We present a case of a 50-year-old man with a lump in the left parotid gland. A 4 cm soft mobile lump was identified in the left parotid gland clinically. CT of the parotid glands and neck was arranged confirming a 4 cm mass, predominantly situated within the superficial lobe anterosuperiorly but extending deep to the expected plane of the facial nerve. The positron emission tomography scan did not show distant metastasis. Complete excision of the tumour was achieved. Histological and immunohistochemical findings were consistent with Extraskeletal Ewing's sarcoma. He is undergoing chemoradiation therapy following surgery.
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Tang YB, Chen ZH, Song HS, Lee CS, Cong HT, Cheng HM, Zhang WJ, Bello I, Lee ST. Vertically aligned p-type single-crystalline GaN nanorod arrays on n-type Si for heterojunction photovoltaic cells. NANO LETTERS 2008; 8:4191-4195. [PMID: 19367961 DOI: 10.1021/nl801728d] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Vertically aligned Mg-doped GaN nanorods have been epitaxially grown on n-type Si substrate to form a heterostructure for fabricating p-n heterojunction photovoltaic cells. The p-type GaN nanorod/n-Si heterojunction cell shows a well-defined rectifying behavior with a rectification ratio larger than 10(4) in dark. The cell has a high short-circuit photocurrent density of 7.6 mAlcm2 and energy conversion efficiency of 2.73% under AM 1.5G illumination at 100 mW/cm2. Moreover, the nanorod array may be used as an antireflection coating for solar cell applications to effectively reduce light loss due to reflection. This study provides an experimental demonstration for integrating one-dimensional nanostructure arrays with the substrate to directly fabricate heterojunction photovoltaic cells.
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Cheng HM, Chamley L. Cryptic natural autoantibodies and co-potentiators. Autoimmun Rev 2008; 7:431-4. [PMID: 18558357 DOI: 10.1016/j.autrev.2008.03.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Accepted: 03/12/2008] [Indexed: 11/30/2022]
Abstract
Natural autoantibodies are normal components of the humoral arm of the immune system found in clinically healthy individuals. There are two subpopulations of natural antibodies, including an overt group of antibodies that are readily detected in unfractionated normal human sera. The other natural antibody subgroup is revealed by physico or biochemical treatment of normal human sera in vitro. Unmasking of this latter cryptic natural autoantibodies (cNA) may occur in vivo by local factors in the tissue environment of disease states. The masking cryptic factors may be immunoglobulin (Ig) or non-Ig in nature. These factors may either be co-inhibitors or co-enhancers of cNA. In the heat-potentiated binding of natural anti-phospholipid antibodies, apolipoprotein H (beta 2-glycoprotein I) appears to act as a co-enhancer. The immuno-relationship between the in vitro and in vivo cNA phenomenon remains to be elucidated.
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Tzeng CT, Tsuei KD, Cheng HM, Chu RY. Covalent bonding and hole-electron Coulomb interaction U in C(60) on Be(0001) surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:176009. [PMID: 21690946 DOI: 10.1088/0953-8984/19/17/176009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have investigated the bonding nature and hole-electron Coulomb interaction U in thin C(60) films on Be(0001) surfaces using valence-band and core-level photoemission, inverse photoemission, and near-edge x-ray absorption spectroscopies. The C(60) monolayer had strong covalent bonding with the Be substrate, producing a nearly insulating film, in contrast to a metallic overlayer due to charge transfer observed on many other metallic surfaces. The effect of polarization of surrounding molecules and the image potential decreases the energy gap and U, but the bonding-antibonding contribution increases the gap at the interface. The measured U in thin solid films agrees well with a model calculation using gas-phase values. The deduced hole-electron attraction on the surface is about 0.7 eV larger than the reported hole-hole repulsion determined by Auger spectroscopy. On the basis of the surface-solid difference, the newly estimated value of U for hole-hole correlation places doped C(60) compounds nearer the metallic side of a Mott transition.
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Cheng HM, Ye ZX, Chiou KR, Lin SJ, Charng MJ. Vascular stiffness in familial hypercholesterolaemia is associated with C-reactive protein and cholesterol burden. Eur J Clin Invest 2007; 37:197-206. [PMID: 17359487 DOI: 10.1111/j.1365-2362.2007.01772.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Familial hypercholesterolaemia (FH) is characterized by very high serum cholesterol and premature coronary atherosclerosis. Arterial stiffness and atherosclerosis are two major underlying pathophysiologies of arterial disease that are predictive of future cardiovascular events. The aims of this study were to quantify atherosclerosis and arterial stiffness and to evaluate their relationship with high sensitive C-reactive protein (hs-CRP) and the level of exposure to high serum cholesterol in FH patients. MATERIALS AND METHODS We measured traditional risk factors, hs-CRP, intima-media thickness (IMT) of carotid artery, and brachial-ankle pulse wave velocity (baPWV) in 35 heterozygous FH subjects and 17 healthy control subjects. Cholesterol-year score (CYS) was calculated to estimate the lifetime cholesterol burden in FH subjects. RESULTS FH subjects had significantly elevated total cholesterol, low-density lipoprotein cholesterol, and carotid IMT compared with those without mutations. Among FH patients, the baPWV and carotid IMT were higher in cases with high cholesterol burden than those without. Similarly, the baPWV and carotid IMT were also higher in cases with elevated hs-CRP (> 1 mg L(-1)) than those without. Multiple linear regression analysis demonstrated CYS and hs-CRP were significant independent predictors of baPWV and IMT in FH patients. CONCLUSIONS Both high cholesterol burden and vascular inflammation are not only associated with atherosclerosis, but also contribute to the development of arterial stiffness in FH patients. Early detection of hypercholesterolaemia in FH patients is warranted to prevent the untoward pathophysiologies.
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Charng MJ, Chiou KR, Chang HM, Cheng HM, Ye ZX, Lin SJ. Identification and characterization of novel low-density lipoprotein receptor mutations of familial hypercholesterolaemia patients in Taiwan. Eur J Clin Invest 2006; 36:866-74. [PMID: 17087781 DOI: 10.1111/j.1365-2362.2006.01735.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Familial hypercholesterolaemia (FH) is an autosomal dominant disease associated with a very high risk of coronary vascular disease. The study objective was to identify patients with FH in Taiwan and characterize novel mutations. MATERIALS AND METHODS Fifty-one patients with suspected FH living in Taiwan were screened for mutations in both the low-density lipoprotein (LDL) receptor and the apolipoprotein (apoB) genes using the multiplex polymerase chain reaction and exon-by-exon DNA sequencing technique. Functional consequences on LDL receptor activity were characterized in vitro for novel mutations and family pedigree was also analyzed. RESULTS Thirteen different functional mutations in the LDL receptor gene and one mutation in the apoB gene were found in 21 patients. Among the 13 mutations in the LDL receptor gene, 10 were single-point missense mutations, one was a two-point mutation in the same allele, one was a non-sense mutation and one was a frame-shift mutation. There were three novel mutations, including two missense mutations (M510K and W512R) and one frame-shift mutation (1953 delTA mutation). The characterization of missense M510K retained 36.2% of the activity of the normal receptor. Conversely, frame-shift 1953 delTA and missense W512R led to defective proteins, with only 0-6% of normal receptor activity. CONCLUSIONS The study identified 13 LDL receptor gene mutations and characterized three novel mutations causing FH in Taiwan. This facilitated a better understanding of FH among the Chinese population and may enable diagnosis of FH at the molecular level at a presymptomatic, early age.
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Yao X, Wu CZ, Wang H, Cheng HM, Lu GQ. Effects of carbon nanotubes and metal catalysts on hydrogen storage in magnesium nanocomposites. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2006; 6:494-8. [PMID: 16573050 DOI: 10.1166/jnn.2006.098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This paper reports a study on nanostructured magnesium composites with carbon nanotubes (CNTs) and catalytic transition metals with high H2 adsorption capacity and fast adsorption kinetics at reduced hydrogenation temperatures. Nanostructures in such a composite are shown to be responsible for improvements in both adsorption capacity and kinetics. It is found that the carbon nanotubes significantly increase the hydrogen storage capacity, and the catalytic transition metals (Fe and Ti) greatly improve the kinetics. This could be understood from the enhancement of diffusion by CNTs and decrease in energy barrier of hydrogen dissociation at the magnesium surface.
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Sun CH, Finnerty JJ, Lu GQ, Cheng HM. Stability of Supershort Single-Walled Carbon Nanotubes. J Phys Chem B 2005; 109:12406-9. [PMID: 16852535 DOI: 10.1021/jp0513014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
How short can single-walled carbon nanotubes (SWNTs) be? How stable are such supershort SWNTs (ss-SWNTs)? This work is the first to address these questions. On the basis of binding energy (E(B)), standard heats of formation , and strain energy (E(S)), we found that SWNTs with only one benzene ring in the axial direction, which we refer to as supershort SWNTs (ss-SWNTs), can be thermodynamically stable. On the basis of the data of E(B), , and E(S), the relative stabilities of ss-SWNTs, fullerenes, polycyclic aromatic hydrocarbons, and butadiyne are discussed. This study has laid a theoretical foundation for the possible synthesis of ss-SWNTs.
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Ong SG, Cheng HM, Soon SC, Goh E, Chow SK, Yeap SS. IgG anti-beta(2) glycoprotein I antibodies in Malaysian patients with antiphospholipid syndrome and systemic lupus erythematosus: prevalence and clinical correlations. Clin Rheumatol 2002; 21:382-5. [PMID: 12223986 DOI: 10.1007/s100670200102] [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
The aim of this study was to investigate the incidence of IgG anticardiolipin antibody (ACL) and IgG anti-beta(2) glycoprotein I antibody (anti-beta2GPI) positivity in patients with primary or secondary antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE), to assess the association between IgG ACL and anti-beta2GPI, and the relationship between the presence of ACL and anti-beta2GPI with the clinical manifestations of APS. IgG ACL and IgG anti-beta2GPI levels were measured in 51 SLE patients, 20 patients with SLE and APS (secondary APS) and 11 primary APS patients using commercially available ELISA kits. Relationships between laboratory data and clinical manifestations of the patients were examined. The incidence of IgG ACL positivity was significantly higher in primary (36.4%) and secondary (40%) APS than in SLE (13.7%) patients (P = 0.02). The incidence of IgG anti-beta2GPI positivity was significantly higher in primary (54.5%) and secondary (35%) APS than in SLE (7.8%) patients (P = 0.0006). Mean levels of IgG ACL and anti-beta2GPI were significantly higher in the primary and secondary APS than in the SLE patients (P = 0.002 for both). A significant relationship was found between IgG ACL and IgG anti-beta2GPI (P = 0.01, R(2) = 0.56). There was a significant correlation between the presence of IgG ACL and a history of thrombosis in the combined primary and secondary APS group, but not in SLE patients. In conclusion, in this study IgG ACL and IgG anti-beta2GPI are closely related and mean levels of IgG ACL and IgG anti-beta2GPI are higher in patients with either primary or secondary APS than in SLE patients.
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Yang CY, Chou CW, Chen SY, Cheng HM. Anterior pituitary failure (panhypopituitarism) with balanced chromosome translocation 46,XY,t(11;22)(q24;q13). ZHONGHUA YI XUE ZA ZHI = CHINESE MEDICAL JOURNAL; FREE CHINA ED 2001; 64:247-52. [PMID: 11458764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Hypopituitarism is the clinical syndrome that results from failure of the anterior pituitary gland to produce its hormones. Hypopituitarism can result from: (1) intrinsic or primary pituitary disease; (2) intrinsic hypothalamic or secondary pituitary disease; or (3) extrinsic extrasellar or parasellar disease. The etiologies of primary hypopituitarism are miscellaneous. The dominant clinical picture of hypopituitarism in the adult is that of hypogonadism. Reports have associated hypopituitarism with anti-pituitary-antibodies, hereditary syndrome and chromosome defects, but hypopituitarism has rarely been associated with balanced chromosome translocation (11;22)(q24;q13). Here, we describe a case of anterior pituitary failure with balanced chromosome translocation. A 19-year-old Chinese teenager presented with failure of pubertal development and sexual infantilism. On examination, the patient had the classic appearance of hypogonadism. Endocrine studies and three combined pituitary function tests revealed panhypopituitarism. A chromosomal study revealed 46,XY,t(11;22)(q24;q13), a balanced translocation between 11q24 and 22q13. Chest films showed delayed fusion of bilateral humeral head epiphyses and bilateral acromions. Scrotal sonography revealed testes were small bilaterally. Magnetic resonance imaging (MRI) of the sella revealed pituitary dwarfism. The patient received 19 months replacement therapy, including steroids (prednisolone 5 mg each day), L-thyroxine (Eltroxin 100 ug each day), and testosterone enanthate 250 mg every two weeks. His height increased 4 cm with secondary sexual characteristics developed, and muscle power increased.
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Sasaki H, Shui YB, Kojima M, Chew SJ, Ono M, Katoh N, Cheng HM, Takahashi N, Sasaki K. Characteristics of cataracts in the Chinese Singaporean. J Epidemiol 2001; 11:16-23. [PMID: 11253906 DOI: 10.2188/jea.11.16] [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: 11/18/2022] Open
Abstract
PURPOSE To conduct an epidemiological survey of cataracts and examine the characteristics of lens opacities in Chinese Singaporeans. The results are then compared with those from two similar surveys previously done in Japan in Noto Area, Honshu, and Amami, Kyushu, respectively. SUBJECTS AND METHODS 468 subjects of > or = 50 years of age, who responded to the invitation to participate, were examined. Examination principally included photo-documentation of the anterior and posterior segments of both eyes. Evaluation and grading of lens opacities were done using graphical analysis of Scheimpflug and retro-illumination images. Inter-group comparisons were based on statistical analysis of cataract prevalence and distribution. RESULTS The prevalence of clear lenses decreased with aging with no significant difference between males and females--a finding common to Singapore and the two Japanese study groups. The prevalence of cataracts (or lens opacities of Grade II and above) in 60-79 year-old Singapore subjects was significantly higher than Noto and Amami subjects in the same age group. Further, cortical opacity was the main type in Singapore subjects in their 50s and which was significantly higher than Noto subjects of the same age group. In all age groups, the distribution and prevalence of both nuclear and subcapsular types in the Singapore group were higher than the two Japanese study groups. CONCLUSIONS Cataracts in Chinese Singaporeans are characterized by a high prevalence of nuclear opacities which was generally seen in tropics and sub-tropics. Our study also suggested the involvement of solar-UV in cortical cataracts as well as that of additional risk factors, such as environmental temperature and race, in nuclear and subcapsular cataract formation.
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Cheng HM. Lupus anticoagulant cofactors and the kidney. Nephron Clin Pract 2000; 78:245. [PMID: 9496755 DOI: 10.1159/000044928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We wish to supplement the useful comment by Stratta et al. [1] on the importance of including lupus anticoagulant (LA) tests when detecting for antiphospholipid autoantibodies (aPL), since monotesting solely with solid-phase aPL immunoassays may not be clinically relevant.
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Jorio A, Dresselhaus G, Dresselhaus MS, Souza M, Dantas MS, Pimenta MA, Rao AM, Saito R, Liu C, Cheng HM. Polarized raman study of single-wall semiconducting carbon nanotubes. PHYSICAL REVIEW LETTERS 2000; 85:2617-2620. [PMID: 10978121 DOI: 10.1103/physrevlett.85.2617] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2000] [Indexed: 05/23/2023]
Abstract
Polarized Raman spectra were obtained from a rope of aligned semiconducting single-wall nanotubes (SWNTs) in the vicinity of the D band and the G band. Based on group theory analysis and related theoretical predictions, the G-band profile was deconvolved into four intrinsic SWNT components with the following symmetry assignments: 1549 cm(-1) [E2(E(2g))], 1567 cm(-1) [A(A(1g))+E1(E(1g))], 1590 cm(-1) [A(A(1g))+E1(E(1g))] and 1607 cm(-1) [E2(E(2g))]. The frequency shifts of the tangential G modes from the 2D graphitelike E(2g(2)) frequency are discussed in terms of the nanotube geometry.
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Tan NW, Saw SM, Lam DS, Cheng HM, Rajan U, Chew SJ. Temporal variations in myopia progression in Singaporean children within an academic year. Optom Vis Sci 2000; 77:465-72. [PMID: 11014673 DOI: 10.1097/00006324-200009000-00007] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Excessive nearwork is believed to be associated with myopia development and progression. To investigate this further, we studied refractive error changes and their correlation with nearwork in a cohort of grade school children in Singapore. METHODS Cycloplegic autorefraction was performed 5 times over 10 months on 168 children aged 7, 9, and 12 years who were further divided into myopic and nonmyopic subgroups based in their initial refractive errors. Information about nearwork was obtained through diaries filled out over 24 h at the commencement of the study. RESULTS Myopia progression was high (overall mean: -0.87 D per year) and largely linear throughout the year, but significantly higher rates were seen after the final school examinations in 7-year-old myopes and nonmyopes. Overall, myopic groups exhibited higher progression rates than nonmyopic groups, although 33.6% of subjects from the latter groups had become myopic by the end of the study. Nearwork scores derived from the diaries were generally not well correlated with overall myopia progression. CONCLUSIONS The tendency for myopia progression rates to increase after the final school examinations in 7-year-olds is interpreted as a delayed effect of the intense nearwork associated with preparing for them. The timing of nearwork-diary data collection at the beginning of the study could be responsible for the poor correlation between these data and overall myopia progression rates.
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Abstract
An attempt was made to study the effect of dietary taurine on the toxicity of oxidized fish oil in male Wistar rats. The rats were fed different diets with or without supplement of 5% taurine and 3% oxidized fish oil. After feeding diet with 3% oxidized fish oil and 5% taurine at the same time, taurine could improve the decrease of body weight and the glutathione (GSH) level in the liver, and the increase of relative ratios of liver and kidney weight to body weight and thiobarbituric acid-reactive substances (TBARS) level in the liver of rats caused by oxidized fish oil It also could reduce the activities of aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) in the plasma of rats caused by oxidized fish oil. It was also found that taurine possessed a good recovering effect and a short-term preventing effect from the toxicity of oxidized fish oil in rats. Judging from these data, this indicates that taurine may play an important role in reducing the toxic effect of oxidized fish oil in rats.
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Sasaki K, Sasaki H, Kojima M, Shui YB, Hockwin O, Jonasson F, Cheng HM, Ono M, Katoh N. Epidemiological studies on UV-related cataract in climatically different countries. J Epidemiol 1999; 9:S33-8. [PMID: 10709348 DOI: 10.2188/jea.9.6sup_33] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cataract epidemiological surveys applying objective judgement through lens images in the climatically different places of Noto and Amami, Japan, Singapore and Reykjavik, Iceland yielded several significant results about the influence of solar UV. 1) The percentage of transparent and of lens opacification was significantly higher in the Reykjavik subjects than in the Singaporeans. 2) The percentages including early changes were higher in Amami and Singapore than in Noto and Reykjavik. 3) Progressed lens opacification was highest in Singapore. While the main type of lens opacification was cortical in Noto and Reykjavik, that of Singapore was nuclear. 4) A significant correlation between cortical opacification and the history of time spent outdoors was noticed. The UV risk for formation and/or progression of cortical opacification should be acceptable from the epidemiological standpoint.
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Liu C, Fan YY, Liu M, Cong HT, Cheng HM, Dresselhaus MS. Hydrogen storage in single-walled carbon nanotubes at room temperature. Science 1999; 286:1127-9. [PMID: 10550044 DOI: 10.1126/science.286.5442.1127] [Citation(s) in RCA: 579] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Masses of single-walled carbon nanotubes (SWNTs) with a large mean diameter of about 1.85 nanometers, synthesized by a semicontinuous hydrogen arc discharge method, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. A hydrogen storage capacity of 4.2 weight percent, or a hydrogen to carbon atom ratio of 0.52, was achieved reproducibly at room temperature under a modestly high pressure (about 10 megapascal) for a SWNT sample of about 500 milligram weight that was soaked in hydrochloric acid and then heat-treated in vacuum. Moreover, 78.3 percent of the adsorbed hydrogen (3.3 weight percent) could be released under ambient pressure at room temperature, while the release of the residual stored hydrogen (0.9 weight percent) required some heating of the sample. Because the SWNTs can be easily produced and show reproducible and modestly high hydrogen uptake at room temperature, they show promise as an effective hydrogen storage material.
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Cheng HM, Aafaqi S, Sam CK. Regulatory natural antibodies in hypertension? Hypertension 1999; 34:e10. [PMID: 10567206 DOI: 10.1161/01.hyp.34.5.e10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lam DSC, Cheuk W, Leung ATS, Fan DSP, Cheng HM, Chew SJ. Eye care when using video display terminals. Hong Kong Med J 1999; 5:255-257. [PMID: 11828065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
OBJECTIVE: To examine the scientific data in the literature regarding eye problems and possible damage during the use of computer video display terminals. DATA SOURCES: Medline and non-Medline literature search and personal experience. STUDY SELECTION: Studies that provided evidence-based information about eye damage and eye care during the use of video display terminals were selected. DATA EXTRACTION: Data were extracted independently by multiple observers. DATA SYNTHESIS: Most studies have shown that the levels of ionizing and non-ionizing radiation that are emitted by video display terminals are not harmful to the human eye. Eye complaints associated with the use of video display terminals include the McCollough effect, accommodative spasm, 'dry eyes', and eye strain. Ergonomic considerations and good visual hygiene can help alleviate symptoms. CONCLUSION: There is currently no convincing evidence that shows that using video display terminals is harmful to the eye.
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Tsubota K, Kwong KK, Lee TY, Nakamura J, Cheng HM. Functional MRI of brain activation by eye blinking. Exp Eye Res 1999; 69:1-7. [PMID: 10375444 DOI: 10.1006/exer.1999.0660] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Functional magnetic resonance imaging (fMRI) was used to map cortical areas that control eye blinking. T2*-weighted asymmetric spin-echo MRI (or BOLD-blood oxygen level dependent-MRI) was used to detect changes caused by focal variations in blood oxygenation. Six normal volunteers and two cases of dry eye (less than 5-mm Schirmer's test) entered the study. The experimental scheme consisted of three cycles of a two-step sequence: (eyes closed)-(blink or blink inhibition). And to minimize contamination from photic activation, the experiments were carried out in a dark environment and the volunteers reported no light perception during the MR scans. In all eight cases, normal blinking (about one blink every 4 sec) activated areas in the orbitofrontal cortex and in some cases, the visual cortex including the anterior portion of the visual cortex and the primary visual cortex. In severe dry eye, blink-inhibition strongly activated the visual cortex even after irritation due to corneal desiccation was removed by topical anesthesia. The blinking process, especially the rate, appears to be controlled in the orbitofrontal cortex. The significance of visual cortex activation in the dark and in the case of severe dry eye still remains unclear; although it may be associated with attention and arousal.
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Cheng HM. Heterogeneity of natural masked autoantibodies: comment on the article by Anderson et al. ARTHRITIS AND RHEUMATISM 1998; 41:2089-90. [PMID: 9811071 DOI: 10.1002/1529-0131(199811)41:11<2089::aid-art35>3.0.co;2-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Cheng HM, Wong FK, Choi KS, Cheng YL, Chak WL, Chan YH, Chau KF, Li CS. Primary prophylaxis with tacrolimus in kidney transplants in China. Transplant Proc 1998; 30:3590-1. [PMID: 9838573 DOI: 10.1016/s0041-1345(98)01149-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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