1
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Lam AK, Roshan R, Miley W, Labo N, Zhen J, Kurland AP, Cheng C, Huang H, Teng PL, Harelson C, Gong D, Tam YK, Radu CG, Epeldegui M, Johnson JR, Zhou ZH, Whitby D, Wu TT. Immunization of Mice with Virus-Like Vesicles of Kaposi Sarcoma-Associated Herpesvirus Reveals a Role for Antibodies Targeting ORF4 in Activating Complement-Mediated Neutralization. J Virol 2023; 97:e0160022. [PMID: 36757205 PMCID: PMC9972917 DOI: 10.1128/jvi.01600-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/11/2023] [Indexed: 02/10/2023] Open
Abstract
Infection by Kaposi sarcoma-associated herpesvirus (KSHV) can cause severe consequences, such as cancers and lymphoproliferative diseases. Whole inactivated viruses (WIV) with chemically destroyed genetic materials have been used as antigens in several licensed vaccines. During KSHV productive replication, virus-like vesicles (VLVs) that lack capsids and viral genomes are generated along with virions. Here, we investigated the immunogenicity of KSHV VLVs produced from a viral mutant that was defective in capsid formation and DNA packaging. Mice immunized with adjuvanted VLVs generated KSHV-specific T cell and antibody responses. Neutralization of KSHV infection by the VLV immune serum was low but was markedly enhanced in the presence of the complement system. Complement-enhanced neutralization and complement deposition on KSHV-infected cells was dependent on antibodies targeting viral open reading frame 4 (ORF4). However, limited complement-mediated enhancement was detected in the sera of a small cohort of KSHV-infected humans which contained few neutralizing antibodies. Therefore, vaccination that induces antibody effector functions can potentially improve infection-induced humoral immunity. Overall, our study highlights a potential benefit of engaging complement-mediated antibody functions in future KSHV vaccine development. IMPORTANCE KSHV is a virus that can lead to cancer after infection. A vaccine that prevents KSHV infection or transmission would be helpful in preventing the development of these cancers. We investigated KSHV VLV as an immunogen for vaccination. We determined that antibodies targeting the viral protein ORF4 induced by VLV immunization could engage the complement system and neutralize viral infection. However, ORF4-specific antibodies were seldom detected in the sera of KSHV-infected humans. Moreover, these human sera did not potently trigger complement-mediated neutralization, indicating an improvement that immunization can confer. Our study suggests a new antibody-mediated mechanism to control KSHV infection and underscores the benefit of activating the complement system in a future KSHV vaccine.
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Affiliation(s)
- Alex K. Lam
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Romin Roshan
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Wendell Miley
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Nazzarena Labo
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - James Zhen
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Andrew P. Kurland
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Celine Cheng
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Haigen Huang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Pu-Lin Teng
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Claire Harelson
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Danyang Gong
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Ying K. Tam
- Acuitas Therapeutics, Vancouver, British Columbia, Canada
| | - Caius G. Radu
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Marta Epeldegui
- Department of Obstetrics and Gynecology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Jeffrey R. Johnson
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Z. Hong Zhou
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Denise Whitby
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Ting-Ting Wu
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
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Abt ER, Rashid K, Le TM, Li S, Lee HR, Lok V, Li L, Creech AL, Labora AN, Mandl HK, Lam AK, Cho A, Rezek V, Wu N, Abril-Rodriguez G, Rosser EW, Mittelman SD, Hugo W, Mehrling T, Bantia S, Ribas A, Donahue TR, Crooks GM, Wu TT, Radu CG. Purine nucleoside phosphorylase enables dual metabolic checkpoints that prevent T cell immunodeficiency and TLR7-associated autoimmunity. J Clin Invest 2022; 132:e160852. [PMID: 35653193 PMCID: PMC9374381 DOI: 10.1172/jci160852] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 05/31/2022] [Indexed: 01/27/2023] Open
Abstract
Purine nucleoside phosphorylase (PNP) enables the breakdown and recycling of guanine nucleosides. PNP insufficiency in humans is paradoxically associated with both immunodeficiency and autoimmunity, but the mechanistic basis for these outcomes is incompletely understood. Here, we identify two immune lineage-dependent consequences of PNP inactivation dictated by distinct gene interactions. During T cell development, PNP inactivation is synthetically lethal with downregulation of the dNTP triphosphohydrolase SAMHD1. This interaction requires deoxycytidine kinase activity and is antagonized by microenvironmental deoxycytidine. In B lymphocytes and macrophages, PNP regulates Toll-like receptor 7 signaling by controlling the levels of its (deoxy)guanosine nucleoside ligands. Overriding this regulatory mechanism promotes germinal center formation in the absence of exogenous antigen and accelerates disease in a mouse model of autoimmunity. This work reveals that one purine metabolism gene protects against immunodeficiency and autoimmunity via independent mechanisms operating in distinct immune lineages and identifies PNP as a potentially novel metabolic immune checkpoint.
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Affiliation(s)
- Evan R. Abt
- Department of Molecular and Medical Pharmacology and
| | - Khalid Rashid
- Department of Molecular and Medical Pharmacology and
| | - Thuc M. Le
- Department of Molecular and Medical Pharmacology and
| | - Suwen Li
- Department of Molecular and Medical Pharmacology and
| | - Hailey R. Lee
- Department of Molecular and Medical Pharmacology and
| | - Vincent Lok
- Department of Molecular and Medical Pharmacology and
| | - Luyi Li
- Department of Surgery, UCLA, Los Angeles, California, USA
| | | | | | - Hanna K. Mandl
- Department of Surgery, UCLA, Los Angeles, California, USA
| | - Alex K. Lam
- Department of Molecular and Medical Pharmacology and
| | - Arthur Cho
- Department of Nuclear Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | | | - Nanping Wu
- Department of Surgery, UCLA, Los Angeles, California, USA
| | | | | | - Steven D. Mittelman
- Division of Pediatric Endocrinology, UCLA Children’s Discovery and Innovation Institute, and
| | - Willy Hugo
- Division of Dermatology, Department of Medicine, UCLA, Los Angeles, California, USA
| | | | | | - Antoni Ribas
- Department of Molecular and Medical Pharmacology and
- Parker Institute for Cancer Immunotherapy, San Francisco, California, USA
- Division of Hematology/Oncology, Department of Medicine
- Division of Surgical Oncology, Department of Surgery
- Jonsson Comprehensive Cancer Center
| | - Timothy R. Donahue
- Department of Molecular and Medical Pharmacology and
- Department of Surgery, UCLA, Los Angeles, California, USA
- Jonsson Comprehensive Cancer Center
| | - Gay M. Crooks
- Division of Pediatric Hematology-Oncology, Department of Pediatrics
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, and
- Department of Pathology and Laboratory Medicine, UCLA, Los Angeles, California, USA
| | - Ting-Ting Wu
- Department of Molecular and Medical Pharmacology and
| | - Caius G. Radu
- Department of Molecular and Medical Pharmacology and
- Jonsson Comprehensive Cancer Center
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Brar G, Farhat NA, Sukhina A, Lam AK, Kim YH, Hsu T, Tong L, Lin WW, Ware CF, Blackman MA, Sun R, Wu TT. Deletion of immune evasion genes provides an effective vaccine design for tumor-associated herpesviruses. NPJ Vaccines 2020; 5:102. [PMID: 33298958 PMCID: PMC7644650 DOI: 10.1038/s41541-020-00251-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 10/02/2020] [Indexed: 12/13/2022] Open
Abstract
Vaccines based on live attenuated viruses often induce broad, multifaceted immune responses. However, they also usually sacrifice immunogenicity for attenuation. It is particularly difficult to elicit an effective vaccine for herpesviruses due to an armament of immune evasion genes and a latent phase. Here, to overcome the limitation of attenuation, we developed a rational herpesvirus vaccine in which viral immune evasion genes were deleted to enhance immunogenicity while also attaining safety. To test this vaccine strategy, we utilized murine gammaherpesvirus-68 (MHV-68) as a proof-of-concept model for the cancer-associated human γ-herpesviruses, Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus. We engineered a recombinant MHV-68 virus by targeted inactivation of viral antagonists of type I interferon (IFN-I) pathway and deletion of the latency locus responsible for persistent infection. This recombinant virus is highly attenuated with no measurable capacity for replication, latency, or persistence in immunocompetent hosts. It stimulates robust innate immunity, differentiates virus-specific memory T cells, and elicits neutralizing antibodies. A single vaccination affords durable protection that blocks the establishment of latency following challenge with the wild type MHV-68 for at least six months post-vaccination. These results provide a framework for effective vaccination against cancer-associated herpesviruses through the elimination of latency and key immune evasion mechanisms from the pathogen.
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Affiliation(s)
- Gurpreet Brar
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Nisar A Farhat
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Alisa Sukhina
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Alex K Lam
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Yong Hoon Kim
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Tiffany Hsu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Leming Tong
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Wai Wai Lin
- Laboratory of Molecular Immunology, Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Carl F Ware
- Laboratory of Molecular Immunology, Infectious and Inflammatory Diseases Center, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | | | - Ren Sun
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA
| | - Ting-Ting Wu
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA, 90095, USA.
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Angarita SAK, Truong B, Khoja S, Nitzahn M, Rajbhandari AK, Zhuravka I, Duarte S, Lin MG, Lam AK, Cederbaum SD, Lipshutz GS. Human hepatocyte transplantation corrects the inherited metabolic liver disorder arginase deficiency in mice. Mol Genet Metab 2018; 124:114-123. [PMID: 29724658 PMCID: PMC5976549 DOI: 10.1016/j.ymgme.2018.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/16/2018] [Accepted: 04/16/2018] [Indexed: 12/13/2022]
Abstract
The transplantation, engraftment, and expansion of primary hepatocytes have the potential to be an effective therapy for metabolic disorders of the liver including those of nitrogen metabolism. To date, such methods for the treatment of urea cycle disorders in murine models has only been minimally explored. Arginase deficiency, an inherited disorder of nitrogen metabolism that presents in the first two years of life, has the potential to be treated by such methods. To explore the potential of this approach, we mated the conditional arginase deficient mouse with a mouse model deficient in fumarylacetoacetate hydrolase (FAH) and with Rag2 and IL2-Rγ mutations to give a selective advantage to transplanted (normal) human hepatocytes. On day -1, a uroplasminogen-expressing adenoviral vector was administered intravenously followed the next day with the transplantation of 1 × 106 human hepatocytes (or vehicle alone) by intrasplenic injection. As the initial number of administered hepatocytes would be too low to prevent hepatotoxicity-induced mortality, NTBC cycling was performed to allow for hepatocyte expansion and repopulation. While all control mice died, all except one human hepatocyte transplanted mice survived. Four months after hepatocyte transplantation, 2 × 1011 genome copies of AAV-TBG-Cre recombinase was administered IV to disrupt endogenous hepatic arginase expression. While all control mice died within the first month, human hepatocyte transplanted mice did well. Ammonia and amino acids, analyzed in both groups before and after disruption of endogenous arginase expression, while well-controlled in the transplanted group, were markedly abnormal in the controls. Ammonium challenging further demonstrated the durability and functionality of the human repopulated liver. In conclusion, these studies demonstrate that human hepatocyte repopulation in the murine liver can result in effective treatment of arginase deficiency.
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Affiliation(s)
- Stephanie A K Angarita
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Brian Truong
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Suhail Khoja
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Matthew Nitzahn
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Molecular Biology Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Abha K Rajbhandari
- Behavioral Testing Core Facility, Department of Psychology and Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Irina Zhuravka
- Behavioral Testing Core Facility, Department of Psychology and Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Sergio Duarte
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Michael G Lin
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Alex K Lam
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Stephen D Cederbaum
- Department of Psychiatry, The David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Intellectual and Developmental Disabilities Research Center at UCLA, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Gerald S Lipshutz
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Molecular Biology Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Department of Psychiatry, The David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Intellectual and Developmental Disabilities Research Center at UCLA, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Department of Urology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Semel Institute for Neuroscience, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States; Broad Center for Regenerative Medicine and Stem Cell Research at UCLA, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
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5
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Lee PC, Truong B, Vega-Crespo A, Gilmore WB, Hermann K, Angarita SA, Tang JK, Chang KM, Wininger AE, Lam AK, Schoenberg BE, Cederbaum SD, Pyle AD, Byrne JA, Lipshutz GS. Restoring Ureagenesis in Hepatocytes by CRISPR/Cas9-mediated Genomic Addition to Arginase-deficient Induced Pluripotent Stem Cells. Mol Ther Nucleic Acids 2016; 5:e394. [PMID: 27898091 PMCID: PMC5155330 DOI: 10.1038/mtna.2016.98] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 09/26/2016] [Indexed: 12/18/2022]
Abstract
Urea cycle disorders are incurable enzymopathies that affect nitrogen metabolism and typically lead to hyperammonemia. Arginase deficiency results from a mutation in Arg1, the enzyme regulating the final step of ureagenesis and typically results in developmental disabilities, seizures, spastic diplegia, and sometimes death. Current medical treatments for urea cycle disorders are only marginally effective, and for proximal disorders, liver transplantation is effective but limited by graft availability. Advances in human induced pluripotent stem cell research has allowed for the genetic modification of stem cells for potential cellular replacement therapies. In this study, we demonstrate a universally-applicable CRISPR/Cas9-based strategy utilizing exon 1 of the hypoxanthine-guanine phosphoribosyltransferase locus to genetically modify and restore arginase activity, and thus ureagenesis, in genetically distinct patient-specific human induced pluripotent stem cells and hepatocyte-like derivatives. Successful strategies restoring gene function in patient-specific human induced pluripotent stem cells may advance applications of genetically modified cell therapy to treat urea cycle and other inborn errors of metabolism.
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Affiliation(s)
- Patrick C Lee
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Brian Truong
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Agustin Vega-Crespo
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - W Blake Gilmore
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Kip Hermann
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Stephanie Ak Angarita
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Jonathan K Tang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Katherine M Chang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Austin E Wininger
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Alex K Lam
- Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Benjamen E Schoenberg
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Stephen D Cederbaum
- Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Intellectual and Developmental Disabilities Research Center at UCLA, Los Angeles, California, USA.,Semel Institute for Neuroscience, UCLA, Los Angeles, California, USA
| | - April D Pyle
- Department of Microbiology, Immunology and Molecular Genetics, UCLA, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - James A Byrne
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Gerald S Lipshutz
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Intellectual and Developmental Disabilities Research Center at UCLA, Los Angeles, California, USA.,Semel Institute for Neuroscience, UCLA, Los Angeles, California, USA.,Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.,Department of Urology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
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Htwe TT, Karim N, Lam AK. Follicular thyroid carcinoma with insular component: a retrospective case study, immunohistochemical analysis and literature review. Singapore Med J 2012; 53:e49-e51. [PMID: 22434304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This is a retrospective case study of a 61-year-old woman diagnosed with follicular thyroid carcinoma. The patient underwent thyroidectomy for the treatment of goitre after being admitted for shortness of breath. Microscopic and immunohistochemical studies were performed, which confirmed follicular carcinoma of the thyroid with an insular component. We also conducted a review of the literature on this uncommon entity.
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Affiliation(s)
- T T Htwe
- Discipline of Pathology, Universiti Kuala Lumpur - Royal College of Medicine Perak, 3 Jalan Greentown, Ipoh 30450, Perak, Malaysia.
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Abstract
BACKGROUND Van der Woude syndrome (VWS) is the most common clefting syndrome in humans. It is characterized by the association of congenital lower lip fistulae with cleft lip and/or cleft palate. VWS individuals have a high prevalence of hypodontia. Although caused by a single gene mutation, VWS has variable phenotypic expression. This study aimed to describe the range of clinical presentations in 22 individuals with VWS to facilitate its diagnosis. METHODS A retrospective study of 22 patients with a diagnosis of VWS was undertaken at the Australian Craniofacial Unit (ACFU) in Adelaide. Three extended families with affected members were included in the study cohort. RESULTS The overall prevalence of lip pits in this study cohort was 86%. Cleft phenotypes included bilateral cleft lip and palate (32%); unilateral cleft lip and palate (32%); submucous cleft palate (23%); and isolated cleft hard and soft palate (9%). Missing permanent teeth were reported in 86% of affected individuals. CONCLUSIONS Submucous cleft palate in VWS may go undiagnosed if the lower lip pits are not detected. Associated hypodontia and resultant malocclusions will also require management by a dental team.
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Affiliation(s)
- A K Lam
- School of Dentistry, The University of Adelaide, South Australia, Australia
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8
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Lam AK, Chan R, Pang PC. The repeatability and accuracy of axial length and anterior chamber depth measurements from the IOLMaster . Ophthalmic Physiol Opt 2001; 21:477-483. [PMID: 11727876 DOI: 10.1016/s0275-5408(01)00016-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
BACKGROUND Axial length and anterior chamber depth have been measured clinically using conventional ultrasound biometry. Recently, a non-contact device has become available to measure these parameters. This study evaluated the repeatability and accuracy of this device. METHODS The axial length and anterior chamber depth were measured by two practitioners on a group of young subjects using the IOLMaster followed by a conventional ultrasound biometer operated by a third practitioner. The accommodation was controlled in ultrasound biometry through a full correction on the non-measured eye and a distant fixation target. RESULTS There was good repeatability and accuracy of axial length assessment. The mean difference between the IOLMaster and ultrasound biometry was -0.099 mm, with 95% limits of agreement between 0.66 and -0.85 mm. The axial length was slightly shorter from the IOLMaster and the difference was not significant. The anterior chamber depth was repeatable but was shown to be deeper than the ultrasound results. The mean difference in anterior chamber depth between the IOLMaster and ultrasound biometry was 0.15 mm, with 95% limits of agreement between 0.34 and -0.03 mm. It is suggested that the former device is not measuring the axial anterior chamber depth. CONCLUSIONS The IOLMaster is a non-contact 'optical' A-scan which is simple to use and good for axial length assessment. The anterior chamber depth assessment should be further evaluated.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon.
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9
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Abstract
BACKGROUND Axial length and anterior chamber depth have been measured clinically using conventional ultrasound biometry. Recently, a non-contact device has become available to measure these parameters. This study evaluated the repeatability and accuracy of this device. METHODS The axial length and anterior chamber depth were measured by two practitioners on a group of young subjects using the IOLMaster followed by a conventional ultrasound biometer operated by a third practitioner. The accommodation was controlled in ultrasound biometry through a full correction on the non-measured eye and a distant fixation target. RESULTS There was good repeatability and accuracy of axial length assessment. The mean difference between the IOLMaster and ultrasound biometry was -0.099 mm, with 95% limits of agreement between 0.66 and -0.85 mm. The axial length was slightly shorter from the IOLMaster and the difference was not significant. The anterior chamber depth was repeatable but was shown to be deeper than the ultrasound results. The mean difference in anterior chamber depth between the IOLMaster and ultrasound biometry was 0.15 mm, with 95% limits of agreement between 0.34 and -0.03 mm. It is suggested that the former device is not measuring the axial anterior chamber depth. CONCLUSIONS The IOLMaster is a non-contact 'optical' A-scan which is simple to use and good for axial length assessment. The anterior chamber depth assessment should be further evaluated.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon.
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10
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Abstract
PURPOSE Posture induced torsional eye movements have rarely been investigated. The current study made use of digital imaging technology to measure the cycloduction resulting from postural change. The effect of cycloduction on reading performance was also investigated. METHODS Thirty subjects were recruited and pictures of the right eye were captured using a digital camera at three postures, i.e. sitting, 90 degrees tilted to the right and 90 degrees tilted to the left. With the identification of a conjunctival landmark, torsional eye movement was measured. The subjects were then required to read a custom designed near chart while in those three postures, the reading card being rotated 90 degrees clockwise or 90 degrees anti-clockwise, to match with the tilting of the head. The reproducibility of the torsional eye movement and reading performance measure was determined in 12 of those 30 subjects. RESULTS Incycloduction was induced when tilting to the right and excycloduction when tilting to the left. This method was found to be reproducible with the 95% confidence limits of 0.80 degrees between visits. The mean incycloduction induced was 6.50 degrees (SD 1.51 degrees ) and 6.41 degrees (SD 1.46 degrees ) for excycloduction. No significant difference in amount was demonstrated (paired t-test: t = 0.624, P = 0.538). No significant difference was found in the reading scores at various postures (Repeated measures ANOVA: df = 2, F = 1.881, P = 0.162). CONCLUSIONS The results presented here demonstrate that we have developed an objective and instantaneous method with good precision, which could be applied in other studies that require the measurement of torsional eye movements. The induced cycloduction did not affect the reading performance.
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Affiliation(s)
- A K Lam
- Department of Optometry & Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
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Abstract
Esophageal squamous cell carcinoma (ESCC) is the predominant histologic subtype of esophageal cancer and characterized by high mortality rate and geographic differences in incidence. With the advances in the field of molecular biology, our understanding of the pathogenesis, epidemiology and behavior of ESCC continues to evolve. The recent development includes research in etiopathogenesis (viruses and cancer susceptibility genes), keratins, tumor related genes (oncogenes, tumor suppressor genes, genes involved in metastasis and apoptosis genes), proliferation-related factors (nuclear proteins, flow cytometry/morphometry, argyrophilic nucleolar organizer region) and factors related to metastases (cell adhesion molecules and enzymes related to degradation of extracellular matrix). There are ranges of molecular techniques potentially available to complement the traditional approaches in the management of ESCC. On the other hand, critics are needed in the interpretation and translation of these research findings from laboratories to clinics. Further investigations, education and collaborations between the various scientific and clinical disciplines are important to successful application of these molecular findings aiming at improving management of patients with ESCC.
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Affiliation(s)
- A K Lam
- Department of Pathology, Queen Mary Hospital, Hong Kong.
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12
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Abstract
The Ocular Blood Flow (OBF) Tonometer is an objective instrument to measure the Pulsatile Ocular Blood Flow (POBF), Pulse Amplitude (PA) and Pulse Rate (PR). It also provides the minimum intraocular pressure (IOPmin) simultaneously. This preliminary study applied the OBF Tonometer on 74 Hong Kong Chinese. They had their POBF measured followed by the Goldmann Applanation Tonometer (GAT). The OBF tonometer overestimates the IOP slightly. The average POBF result was smaller (661.2 microliters/min) than the previous studies. The effect of myopia of our sample (mean spherical equivalent -4.27 D) could be one of the contributing factors. Other factors include age and racial difference. Twenty-two subjects had their POBF measured again by the same practitioner and different practitioner for the reproducibility variation assessments. The POBF, PA and IOPmin were found to be repeatable between sessions. The POBF "norm" in Hong Kong Chinese needs to be established from a larger sample size and from a comparison on an age and refraction matched Caucasian group.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Hong Kong
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13
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Kwan LK, Lam AK, Kwan CK, Yeung PH. The characteristics of near prism induced fixation disparity curve in Hong Kong Chinese. Ophthalmic Physiol Opt 1999; 19:393-400. [PMID: 10768020 DOI: 10.1046/j.1475-1313.1999.00456.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The characteristics of prism induced fixation disparity curve at near were studied in 56 asymptomatic young adult Hong Kong Chinese (average age 21 years). The percentage distribution of types of fixation disparity curves was found to be similar to some previous studies, with a higher prevalence of Type I curve (64.3%), followed by Type II (28.6%) and Type III (7.1%) curves. No Type IV curve was revealed from the sample. Two modified measurement approaches were applied to study the effect of measurement techniques on the parameters of fixation disparity curve obtained. A thorough description of the techniques was given. Although a significant difference in the x- and y-intercepts was obtained between different methods, the curve type and slope were not affected. The average y-intercepts (fixation disparity) were 2.72 min of arc and 3.54 min of arc from two methods respectively. Forty-one subjects had x-intercept (associated phoria) found from the curve. The average values were 2.42 delta base-out and 3.54 delta base-out from two methods respectively.
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Affiliation(s)
- L K Kwan
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Kowloon, Hong Kong
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14
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Abstract
PURPOSE The current study compared the central corneal curvature and the refractive error of Hong Kong Chinese to study the validity of Javal's rule. METHODS Subjects without corneal pathology were recruited at different age ranges. Their refractive error and the corneal curvature were measured and compared for the right eye only. Two instruments were used for the measurement of corneal curvature including a conventional Bausch & Lomb (B&L) keratometer and a computer-assisted videokeratoscope (TMS-1). RESULTS Subjects age ranged from 21 years to 77 years were recruited and were categorized into five groups according to age. The Bausch & Lomb keratometer was found to provide corneal information similar to that from the TMS-1. The corneal astigmatism was found to change from with-the-rule to against-the-rule with advancing age. The spectacle astigmatism followed a similar trend. There was a hyperopic shift in the spherical component of the refractive error with aging as well. A regression equation: Spectacle astigmatism = 0.93 (Corneal astigmatism) + (-0.58D x 90) was found, which is similar to the simplified Javal's rule. There was a shift of 1.03D in hyperopia (spherical equivalent) for each decade. CONCLUSIONS Both the corneal and spectacle astigmatism demonstrated a shift from with-the-rule to against-the-rule with age. The simplified Javal's rule is more suitable for predicting the spectacle astigmatism from corneal astigmatism in Hong Kong Chinese.
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Affiliation(s)
- A K Lam
- Department of Optometry & Radiography, Hong Kong Polytechnic University
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15
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Kee CS, Do TC, Lai RY, Wong G, Lam AK. Could a cycloplegic agent be replaced by a fogging or a corrective lens in the biometric measurement of the crystalline lens? Ophthalmic Physiol Opt 1998; 18:521-6. [PMID: 10070547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
This study investigated whether a fogging or a corrective lens could be used to replace a cycloplegic agent in the ultrasonic measurement of crystalline lens thickness in myopia. A group of 28 Hong Kong Chinese adults with myopia was recruited. The crystalline lens thickness of the examined eye was measured by A-scan ultrasonography while the fixating eye was in one of three conditions: fog (+2.00 D fogging lens), full corrective lens, or cycloplegia (50 minutes after instillation of 1% cyclopentolate HCl). We found that the mean lens thickness was significantly different between the three conditions in our myopic subjects. The mean crystalline lens thickness under fogging and corrective lens conditions was significantly greater than the cycloplegic condition by 0.09 mm and 0.11 mm, respectively. The 95% limits of agreement compared to cycloplegia (fogging: -0.32 to +0.14; corrective: -0.35 to +0.13) showed marked intersubject variability, indicating that there is a risk of overestimating the lens thickness when substituting cycloplegia with either a fogging or a corrective lens.
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Affiliation(s)
- C S Kee
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
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16
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Abstract
PURPOSE This study investigated the topographic corneal thickness in four groups of Hong Kong Chinese. METHODS The corneal thickness was determined with an ultrasound pachometer mounted on a X-Y plate. A head rest was used to reduce further any movement from the subject during the measurement. After the central cornea was measured, the peripheral cornea was determined on nasal, temporal, superior, and inferior regions, 2 and 5 mm from the corneal center. RESULTS The corneal thickness was not significantly different between the right and left eyes. For the right eye, there was no significant thickness difference for the four quadrants at a midperipheral and peripheral region, respectively. There was a general thinning of the corneal thickness at all regions from aging but no difference between the genders. CONCLUSION The corneal thickness in our subjects was similar to that in other studies. The mean central corneal thickness varied from 541.7 (m to 560.8 microm, dependent on age. This study provides some information for the future studies of Chinese corneal thickness.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Kowloon
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17
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Abstract
The Ret proto-oncogene is known to be rearranged in papillary carcinoma of the thyroid. The aim of this study was to investigate the in situ expression of Ret mRNA in thyroid tumors. Formalin-fixed, paraffin-embedded tissue specimens from 45 thyroid lesions were examined by in situ hybridization using manual capillary action technology (MicroProbe Staining System) and a 52-base synthetic biotinylated oligonucleotide probe complementary to the tyrosine-kinase domain of Ret proto-oncogene. The clinicopathological features of these patients with thyroid lesions also were noted. Ret was noted in 17 (43%) of 40 papillary carcinomas. In contrast, none of the three follicular carcinomas, follicular adenoma, nodular hyperplasia, and normal thyroids, showed evidence of Ret mRNA. Our results showed that, in papillary thyroid carcinoma, there is an important role of Ret activation. The Ret staining could be a useful marker for papillary carcinoma.
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Affiliation(s)
- A K Lam
- Department of Pathology, University of Hong Kong, Queen Mary Hospital, Hong Kong
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18
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Lam AK, Douthwaite WA. The effect of an artificially-elevated intraocular pressure on corneal thickness in Chinese eye. Ophthalmic Physiol Opt 1997; 17:414-20. [PMID: 9390368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We measured the central corneal thickness and the applanation intraocular pressure (IOP) on 45 Hong Kong Chinese. There was no obvious relationship between these two parameters, as different from other literatures. It could be due to either a limited number of subjects with a high IOP level (only six subjects with IOP > or = 22 mmHg), or Chinese has a thicker central cornea in general. The mean central cornea of our subjects was thicker (566 +/- 36 microns) than some previous findings. Thirty subjects had their intraocular pressure further increased by adopting a 40 degrees head-down posture. Their IOP and topographic corneal thickness were measured again. There was no significant change in the central corneal thickness even though the IOP was elevated by 11.7 mmHg. However the nasal cornea demonstrated a thinning effect (by some 18 microns) during the IOP elevation but it returned to the pre-inverted level after returning to a sitting posture for 5 min. Further investigation with more corneal regions being measured would be valuable to evaluate the in vivo effect of IOP elevation from glaucoma attack on corneal thickness.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Hong Kong
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19
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Lam AK, Douthwaite WA. Does the change of anterior chamber depth or/and episcleral venous pressure cause intraocular pressure change in postural variation? Optom Vis Sci 1997; 74:664-7. [PMID: 9323738 DOI: 10.1097/00006324-199708000-00028] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PURPOSE Previous studies have found that the intraocular pressure (IOP) variation from postural change is due to the obstruction of aqueous outflow by an increase in episcleral venous pressure. This study investigated if any shift of anterior lens position from postural variation would be another contributing factor. METHODS Thirty-three Chinese subjects were recruited with their IOP and anterior chamber depth (ACD) measured in the sitting, supine, and prone postures. The IOP was measured using a Pulsair 2000 noncontact tonometer and ACD with a Nidek US-2000 EchoScan unit. RESULTS The highest IOP was obtained in the prone position and this value was significantly different from the IOP obtained in other postures, whereas there was no significant difference in ACD. CONCLUSIONS Because no significant variation in ACD was demonstrated, the prone and supine IOP variation could be due to something other than the change in lens position. However, a higher IOP in the prone position rather than in the supine position also suggests that it is not merely the episcleral venous pressure causing the IOP change. Investigation of the entire iris profile at different postures would be more informative in future studies.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic, Hong Kong
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20
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Lam AK, Douthwaite WA. Measurement of posterior corneal asphericity on Hong Kong Chinese: a pilot study. Ophthalmic Physiol Opt 1997; 17:348-56. [PMID: 9390379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The posterior corneal p-value and apical radius of 60 Hong Kong Chinese were assessed. The values were derived based on the information of the anterior corneal topography and the corneal thickness in different regions. The mean posterior corneal apical radius along the horizontal meridian was 6.51 mm (SD +/- 0.40 mm) and the p-value was 0.34 (SD +/- 0.38). The apical radius is greater while the p-value is smaller than a previous study using a similar principle. This may indicate a flatter posterior cornea and greater peripheral flattening in Hong Kong Chinese. No significant difference between the nasal and temporal corneal thickness, nasal and temporal posterior p-value and apical radius was demonstrated. The right and left eyes were also similar in different ocular parameters apart from a smaller anterior corneal p-value on the right eye (R eye: 0.70 +/- 0.13; L eye: 0.67 +/- 0.12), but the difference may not be significant clinically. The method used here is simple and the generation of posterior corneal topography is informative.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Kowloon, Hong Kong
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21
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Lam AK, Douthwaite WA. The effect of an artificially elevated intraocular pressure on the central corneal curvature. Ophthalmic Physiol Opt 1997; 17:18-24. [PMID: 9135808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Twenty-three optometry students with normal corneal condition were recruited. The intraocular pressure and central corneal curvature of the right eye were measured in a sitting and a 30 degrees head-down posture. The mean (standard deviation) IOPs before and during posture change were 15.6 (2.4) mmHg and 22.1 (2.3) mmHg respectively. This 6.5 mmHg mean rise in IOP was found to be statistically significant which is similar to the results from previous studies. The mean changes in radius of corneal curvature and the orientation of the axis of the vertical principal meridian were 0.02 mm (SD 0.025 mm) and 2.4 degrees (SD 10.4 degrees) respectively. No significant variation was demonstrated on these keratometric results due to the 30 degrees head-down posture. The maximum change in radius of curvature was only 0.055 mm for one subject. Perhaps this amount of pressure rise was not sufficient enough to distort the corneal surface centrally. Another possibility could be an even distribution of the elevated pressure around the cornea, or the distribution of pressure is not even but could not be revealed by a conventional keratometer.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
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22
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Lam AK, Douthwaite WA. A pilot study on the measurement of central posterior corneal radius in Hong Kong Chinese using Purkinje image technique. Ophthalmic Physiol Opt 1997; 17:68-74. [PMID: 9135815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The central posterior corneal radius was measured by assessing the first and second Purkinje images produced from a modified keratometer. This method was initially assessed by measuring five PMMA lens buttons with back surface radii from 6.2 mm to 7.0 mm. It was reasonably accurate when compared with the measurements made using a conventional radiuscope. The technique was found to be repeatable for human subjects measured on three separate occasions. The mean central posterior corneal radii from a group of 30 Hong Kong Chinese were 6.64 mm (SE 0.05 mm) and 6.39 mm (SE 0.05 mm) along the horizontal and vertical meridians respectively. These results are similar to previous studies using a similar technique. The posterior corneal radii were found to be similar for right and left eyes and there were no gender differences.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Hong Kong
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23
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Lam AK, Chau AS, Lam WY, Leung GY, Man BS. Effect of naturally occurring visual acuity differences between two eyes in stereoacuity. Ophthalmic Physiol Opt 1996; 16:189-95. [PMID: 8977881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Stereoacuity was measured in 30 subjects with a naturally occurring visual acuity (VA) difference between the eyes. The stereoacuity was measured by a modified Howard's apparatus using the staircase method and VA was measured with log MAR charts. Stereoacuity was worse in subjects with a large VA difference between the two eyes; the correlation between stereoacuity and VA difference was significant (r = 0.76, P < 0.001). Neither the VA of the worse eye nor of the better eye contributed to the reduction in stereoacuity. The deterioration was more obvious if VA difference between the two eyes was one line or more (correlation coefficient, r= 0.88, P < 0.001). This study also reinforces the use of a > or = 70% stereothreshold when attempt stereoacuity results to compare with other studies.
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Affiliation(s)
- A K Lam
- Optometry Section, Hong Kong Polytechnic University, Hong Kong
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24
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Lam AK, Douthwaite WA. Application of a modified keratometer in the study of corneal topography on Chinese subjects. Ophthalmic Physiol Opt 1996; 16:130-4. [PMID: 8762774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A corneal topography study was carried out on Hong Kong Chinese subjects using a modified keratometer. The Chinese corneal topography measured by this modified keratometer was similar to other studies using the Wesley-Jessen Photo Electronic Keratoscopy (PEK) System 2000. The mean p-values along the horizontal meridian and the vertical meridian were 0.82 and 0.87, respectively. A negative correlation was found between the p-value and the central corneal radius along the horizontal meridian which may indicate that a steeper central cornea will have a greater p-value. However, the correlation coefficient of 0.56 was not too certain for this conclusion to be drawn. A difference of 0.04 was found between the horizontal p-value and the vertical p-value, which may be a result of the tight lid tension along the vertical meridian. This modified keratometer can be considered as an inexpensive instrument for the study of corneal topography.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University
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25
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Abstract
Using model eyes the sensitivity to orientation of an Alcon hand-held autokeratometer was assessed after calibration with steel balls. It was concluded that the keratometer should be used in a vertical position (6:00/12:00) in order for axis references to be accurate. Corneal curvature of optometry students was measured using the autokeratometer and a Bausch and Lomb keratometer. The results showed that the autokeratometer was similar to the Bausch and Lomb keratometer in measuring the vertical and horizontal principal meridians, and the axis of the vertical principal meridian. This hand-held keratometer is useful for screening purposes and measuring corneas of infants.
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Affiliation(s)
- A K Lam
- Department of Optometry and Radiography, Hong Kong Polytechnic University, Hung Hom
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26
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Lam AK, Fedorak PM, Prepas EE. Biotransformation of the Cyanobacterial Hepatotoxin Microcystin-LR, as Determined by HPLC and Protein Phosphatase Bioassay. Environ Sci Technol 1995; 29:242-246. [PMID: 22200225 DOI: 10.1021/es00001a030] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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27
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Lam AK, Douthwaite WA. Derivation of corneal flattening factor, p-value. Ophthalmic Physiol Opt 1994; 14:423-7. [PMID: 7845703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A mathematical equation was derived to calculate the corneal p-value based on the central and peripheral corneal radii and the corresponding semichord diameters. The calculation was simplified by a computer program written using GWBASIC. The accuracy of corneal p-value generated from this program was checked with Douthwaite's modified keratometer with good correlation. This program could be used to find out the corneal p-value and apical radius ro for any topographic keratometer which only provides central and peripheral radii without any information of the p-value and apical radius.
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Affiliation(s)
- A K Lam
- Optometry Section, Hong Kong Polytechnic
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28
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Abstract
The conventional rigid-lens fitting method uses fluorescein to assess the tear layer beneath a trial lens on the corneal surface. A more advanced technique, which uses a computer program to determine the back surface specifications of a contact lens from a pre-set tear layer thickness, has been studied. No significant difference was found in terms of corneal physiological changes between the conventionally determined contact lenses and computer-determined contact lenses after a three-month wearing period. The results suggest that there is little difference in the two methods of fitting. However, the computer determined method was found to be more efficient in terms of chair time, and also can aid inexperienced rigid lens practitioners to select the appropriate lens back surface curves.
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Affiliation(s)
- A K Lam
- Optometry Section, Hong Kong Polytechnic
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29
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Abstract
After simple modification, a keratometer can measure both the central and peripheral regions of the cornea. The apical radius and p-value of the cornea can be determined with this information using a computer program. This computer program suggests lens parameters similar to those chosen by conventional methods in rigid lens fitting. The computerized fitting method is also applicable to Chinese subjects.
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Affiliation(s)
- A K Lam
- Optometry Section, Hong Kong Polytechnic
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30
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Abstract
We report a case of cardiac inflammatory pseudotumour which we believe caused sudden death in a previously healthy 55-year-old Chinese female. The features of inflammatory pseudotumours are briefly reviewed. Cardiac lesions are very rare, have only been reported in children before, and have not been associated with sudden death.
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Affiliation(s)
- P Dickens
- Department of Pathology, University of Hong Kong
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31
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Abstract
A 47-year-old man had symptoms of nemaline myopathy for approximately 1 year. There were marked elevations of creatine kinase, a feature not previously described. Examination of the nervous system at autopsy failed to reveal any abnormalities.
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