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Tsui HL, Fung EPY, Kwok KM, Wong LKM, Lo LW, Mak WS. Magnetic Marker Wireless Localisation versus Radioguided Localisation of Nonpalpable Breast Lesions. Hong Kong Journal of Radiology 2022. [DOI: 10.12809/hkjr2117267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- HL Tsui
- Department of Radiology and Organ Imaging, United Christian Hospital, Hong Kong
| | - EPY Fung
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - KM Kwok
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - LKM Wong
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - LW Lo
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - WS Mak
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
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Cheung WP, Lo LW, Wong KM, Mak WS, Kwok KM, Fung EPY. Imaging Findings of Progressing Rosai–Dorfman Disease of the Breast: a Case Report and Literature Review. Hong Kong Journal of Radiology 2021. [DOI: 10.12809/hkjr2117156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- WP Cheung
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - LW Lo
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - KM Wong
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - WS Mak
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - KM Kwok
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
| | - EPY Fung
- Department of Diagnostic and Interventional Radiology, Kwong Wah Hospital, Hong Kong
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Lo LW, Wong T, Fung EPY, Lai MH, She HL, Kwok KM, Lee CM. Magnetic Resonance Imaging of Benign Breast Lesions. Hong Kong J Radiol 2017. [DOI: 10.12809/hkjr1715318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Lam CH, Lo LW, Ma KF, Chan LK. Stercoral Perforation of the Sigmoid Colon with Faecal Peritonitis: Report of Two Cases. Hong Kong J Radiol 2013. [DOI: 10.12809/hkjr1312121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Sham CO, Cheng YW, Ho KW, Lai PH, Lo LW, Wan HL, Wong CY, Yeung YN, Yuen SH, Wong AY, Wong AYC. Do-not-resuscitate decision: the attitudes of medical and non-medical students. J Med Ethics 2007; 33:261-5. [PMID: 17470500 PMCID: PMC2598130 DOI: 10.1136/jme.2005.014423] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
OBJECTIVES To study the attitudes of both medical and non-medical students towards the do-not-resuscitate (DNR) decision in a university in Hong Kong, and the factors affecting their attitudes. METHODS A questionnaire-based survey conducted in the campus of a university in Hong Kong. Preferences and priorities of participants on cardiopulmonary resuscitation in various situations and case scenarios, experience of death and dying, prior knowledge of DNR and basic demographic data were evaluated. RESULTS A total of 766 students participated in the study. There were statistically significant differences in their DNR decisions in various situations between medical and non-medical students, clinical and preclinical students, and between students who had previously experienced death and dying and those who had not. A prior knowledge of DNR significantly affected DNR decision, although 66.4% of non-medical students and 18.7% of medical students had never heard of DNR. 74% of participants from both medical and non-medical fields considered the patient's own wish as the most important factor that the healthcare team should consider when making DNR decisions. Family wishes might not be decisive on the choice of DNR. CONCLUSIONS Students in medical and non-medical fields held different views on DNR. A majority of participants considered the patient's own wish as most important in DNR decisions. Family wishes were considered less important than the patient's own wishes.
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Affiliation(s)
- C O Sham
- University of Hong Kong, Hong Kong.
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Lo LW, Cheng JJ, Chiu JJ, Wung BS, Liu YC, Wang DL. Endothelial exposure to hypoxia induces Egr-1 expression involving PKCalpha-mediated Ras/Raf-1/ERK1/2 pathway. J Cell Physiol 2001; 188:304-12. [PMID: 11473356 DOI: 10.1002/jcp.1124] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hypoxia induces endothelial dysfunction that results in a series of cardiovascular injuries. Early growth response-1 (Egr-1) has been indicated as a common theme in vascular injury. Here we demonstrates that in bovine aortic endothelial cells (ECs) subjected to hypoxia (PO(2) approximately 23 mmHg), rapidly increased Egr-1 mRNA expression which peaked within 30 min and decreased afterwards. Treatment of ECs with PD98059, a specific inhibitor to mitogen-activated protein kinase (MAPK/ERK), inhibited this hypoxia-induced Egr-1 expression. The involvement of ERK pathway was further substantiated by the inhibition of Egr-1 promoter activities when ECs were co-transfected with a dominant negative mutant of Ras (RasN17), Raf-1 (Raf 301), or a catalytically inactive mutant of ERK2 (mERK). In addition, the hypoxia-induced transcriptional activity of Elk-1, an ERK substrate, was abolished by administration of PD98059. Addition of calphostin C, a protein kinase C (PKC) inhibitor, completely blocked the hypoxia-augmented Egr-1 expression. The likewise occurred while exposing ECs to D609 to inhibit phospholipase C and BAPTA/AM to chelate intracellular calcium. Hypoxia to ECs increased ERK phosphorylation within 10 min and which was abolished by administration of PD98095, calphostin C, and BAPTA/AM. Hypoxia triggered a transient translocation of PKCalpha from cytosol to membrane fraction concurrent with the association of PKCalpha to Raf-1. Involvement of PKCalpha in mediating ERK activation was further confirmed by the inhibition of ERK and the subsequent Egr-1 gene induction with antisense oligonucleotides to PKCalpha. These results indicate that ECs under hypoxia induce Egr-1 expression and this induction requires calcium, phospholipase C activation, and PKCalpha-mediated Ras/Raf-1/ERK1/2 signaling pathway. Our finding support the importance of specific PKC isozyme linked to MAPK pathway in the regulation of endothelial responses to hypoxia.
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Affiliation(s)
- L W Lo
- Departmant of Applied Chemistry, National Chi Nan University, Nantou, Taiwan, ROC
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Chiu JJ, Wung BS, Hsieh HJ, Lo LW, Wang DL. Nitric oxide regulates shear stress-induced early growth response-1. Expression via the extracellular signal-regulated kinase pathway in endothelial cells. Circ Res 1999; 85:238-46. [PMID: 10436166 DOI: 10.1161/01.res.85.3.238] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Endothelial cells (ECs) subjected to shear stress constantly release nitric oxide (NO). The effect of NO on shear stress-induced endothelial responses was examined. ECs subjected to shear stress induced a transient and shear force-dependent increase in early growth response-1 (Egr-1) mRNA levels. Treatment of ECs with an NO donor, S-nitroso-N-acetylpenicillamine (SNAP) or 3-morpholinosydnonimine (SIN-1), inhibited this shear stress-induced Egr-1 expression. Conversely, an NO synthase inhibitor to ECs, N(G)-monomethyl-L-arginine, augmented this Egr-1 expression. NO modulation of Egr-1 expression was demonstrated by functional analysis of Egr-1 promoter activity using a chimera containing the Egr-1 promoter region (-698 bp) and reporter gene luciferase. In contrast to the enhanced promoter activity after N(G)-monomethyl-L-arginine treatment, shear stress-induced Egr-1 promoter activity was attenuated after ECs were treated with an NO donor. ECs cotransfected with a dominant negative mutant of Ras (RasN17), Raf-1 (Raf301), or a catalytically inactive mutant of extracellular signal-regulated kinase (ERK)-2 (mERK) inhibited shear stress-induced Egr-1 promoter activity. NO modulation of the signaling pathway was shown by its inhibitory effect on shear stress-induced ERK1/ERK2 phosphorylation and activity. This inhibitory effect was further substantiated by the inhibition of NO on both the shear stress-induced transcriptional activity of Elk-1 (an ERK substrate) and the promoter activity of a reporter construct containing serum response element. NO-treated ECs resulted in a reduction of binding of nuclear proteins to the Egr-1 binding sequences in the platelet-derived growth factor-A promoter region. These results indicate that shear stress-induced Egr-1 expression is modulated by NO via the ERK signaling pathway in ECs. Our findings support the importance of NO as a negative regulator in endothelial responses to hemodynamic forces.
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MESH Headings
- Calcium-Calmodulin-Dependent Protein Kinases/physiology
- Cells, Cultured
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Early Growth Response Protein 1
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/enzymology
- Endothelium, Vascular/metabolism
- Gene Expression/drug effects
- Gene Expression/physiology
- Genes, Reporter/genetics
- Humans
- Immediate-Early Proteins
- Nitric Oxide/pharmacology
- Phosphorylation
- Platelet-Derived Growth Factor/genetics
- Platelet-Derived Growth Factor/metabolism
- Promoter Regions, Genetic/drug effects
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins c-raf/physiology
- RNA, Messenger/metabolism
- Stress, Mechanical
- Time Factors
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription, Genetic/drug effects
- ets-Domain Protein Elk-1
- ras Proteins/physiology
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Affiliation(s)
- J J Chiu
- Cardiovascular Division, Institute of Biomedical Sciences, Academia Sinica, Taiwan University, Taipei, Taiwan, ROC
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Affiliation(s)
- L W Lo
- Department of Biochemistry and Biophysics, Medical School, University of Pennsylvania, Philadelphia 19104, USA
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Rumsey WL, Abbott B, Lo LW, Vinogradov SA, Wilson DF. Imaging of oxygen distribution in the surface and deep areas of the kidney. Adv Exp Med Biol 1997; 411:591-5. [PMID: 9269477 DOI: 10.1007/978-1-4615-5865-1_73] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- W L Rumsey
- Zeneca Pharmaceuticals, Wilmington, Delaware 19897, USA
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Lo LW, Jenkins WT, Vinogradov SA, Evans SM, Wilson DF. Oxygen distribution in the vasculature of mouse tissue in vivo measured using a near infra red phosphor. Adv Exp Med Biol 1997; 411:577-83. [PMID: 9269475 DOI: 10.1007/978-1-4615-5865-1_71] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Oxygen dependent quenching of phosphorescence has been used to measure the oxygenation of tissue in mice, including the differences between normal tissue and that of a murine tumor. Approximately 0.3 mg of the phosphorescence oxygen probe, Green 2W, was injected into the tail vein of tumor bearing mice. The mice were immobilized using an anesthetic cocktail and illuminated with flashes (< 4 microseconds t1/2) of light of 636 +/- 15 nm. The emitted phosphorescence (790 nm max.) was measured using an imaging phosphorimeter with an intensified CCD camera, an instrument which provides two dimensional digital maps of oxygen pressure. Both the illumination light and the phosphorescence were in the near infra red region of the spectrum, where skin and tissue have little absorption. The light can therefore readily pass through the skin and centimeter thickness of tissue. Mice are sufficiently small that the oxygen pressure maps could be obtained by illuminating from either the same or the opposite side as the camera (and tumor). The tumors were observed as regions with oxygen pressures substantially below those of the surrounding normal tissue. Thus, it is possible to non-invasively detect these tumors and to monitor their internal oxygen pressure in real time and through cm of tissue.
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Affiliation(s)
- L W Lo
- Department of Biochemistry and Biophysics and of Radiation Oncology Medical School, University of Pennsylvania 19104, USA
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Lo LW, Koch CJ, Wilson DF. Calibration of oxygen-dependent quenching of the phosphorescence of Pd-meso-tetra (4-carboxyphenyl) porphine: a phosphor with general application for measuring oxygen concentration in biological systems. Anal Biochem 1996; 236:153-60. [PMID: 8619481 DOI: 10.1006/abio.1996.0144] [Citation(s) in RCA: 191] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Oxygen-dependent quenching of phosphorescence is a function of the frequency of collision between the phosphor and molecular oxygen and of the efficiency of energy transfer during these collisions. Thus, quenching is dependent on the rate of diffusion of the phosphor and its molecular environment. For measurements in biological samples, the Pd-porphyrin is bound to serum albumin, and this provides a uniform microenvironment for the phosphor which is relatively unaffected by changes in the pH and ionic composition of the medium. Calibration of the phosphor is of particular value because it is absolute, i.e., the calibration is valid independent of the laboratory and the time of measurement. This paper reports the calibration constants determined for Pd-meso-tetra (4-carboxyphenyl) porphine, as measured by two independent methods: by stoichiometric titration of the oxygen with ascorbate in the presence of ascorbate oxidase and by comparison with a high-accuracy oxygen electrode. The measurements were carried out in a specially designed thermostatted vessel in which the oxygen electrode and phosphorescence lifetime measurements of oxygen were made simultaneously. The calibration constants for the oxygen-dependent quenching of the phosphorescence of Pd-meso-tetra (4-carboxyphenyl) porphine were determined as a function of albumin concentration, ionic strength in medium, pH, and temperature.
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Affiliation(s)
- L W Lo
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, 19104, USA
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Vinogradov SA, Lo LW, Jenkins WT, Evans SM, Koch C, Wilson DF. Noninvasive imaging of the distribution in oxygen in tissue in vivo using near-infrared phosphors. Biophys J 1996; 70:1609-17. [PMID: 8785320 PMCID: PMC1225130 DOI: 10.1016/s0006-3495(96)79764-3] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A newly developed water-soluble phosphor suitable for measuring oxygen pressure in the blood (Green 2W) was used for noninvasive, in vivo imaging of oxygen distribution in the vascular systems of mice. Oxygen quenches the phosphorescence of Green 2W, measured in the presence of 2% albumin, according to the Stern-volmer relationship. This oxygen-dependent quenching of phosphorescence has been used to obtain digital maps of the oxygen distribution in the tissue vasculature. EMT-6 mammary carcinoma tumors were grown by injecting 1 x 10(6) cells in 0.1-ml carrier into the subcutaneous space over the muscle on the hindquarter. When the tumors were approximately 8 mm in diameter, 300 micrograms of phosphorescence probe (Green 2W; absorption maximum 636 nm) was injected into the tail vein. The mice were immobilized with intraperotoneal Ketamine (133 mg/kg) and Xylazine (10 mg/kg) and illuminated with flashes (< 4-microseconds t1/2) of light of 630 +/- 12 nm. The emitted phosphorescence (790-nm maximum) was imaged an intensified CCD camera. Images were collected beginning at 30, 50, 80, 120, 180, 240, 420, and 2500 microseconds after the flash and used to calculate digital maps of the phosphorescence lifetimes and oxygen pressure. Both the illumination light and the phosphorescence were in the near-infrared region of the spectrum, where tissue has greatly decreased absorbance. The light therefore readily passed through the skin and centimeter thicknesses of tissue. The oxygen maps could be obtained by illuminating from the side of the mouse opposite the camera (and tumor). The tumors were readily observed as regions with oxygen pressures substantially below those of the surrounding tissue. Thus, phosphorescence measurements can noninvasively detect volumes of tissue with below-normal oxygen pressure in the presence of much larger volumes of tissue with normal oxygen pressures. In addition, tissue oxygen pressures can be monitored in real time, even through centimeter thicknesses of tissue.
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Affiliation(s)
- S A Vinogradov
- Department of Biochemistry and Biophysics, Medical School, University of Pennsylvania, Philadelphia 19104, USA.
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Chang MJ, Lin CY, Lo LW, Lin RS. Biological monitoring of exposure to chlorpyrifos by high performance liquid chromatography. Bull Environ Contam Toxicol 1996; 56:367-374. [PMID: 8825957 DOI: 10.1007/s001289900053] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- M J Chang
- Department of Public Health, Chang Gung College of Medicine and Technology, Tao-Yuan, Taiwan
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Affiliation(s)
- D F Wilson
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia 19104, USA
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Lo LW, Koropatnick J, Stich HF. The mutagenicity and cytotoxicity of selenite, "activated" selenite and selenate for normal and DNA repair-deficient human fibroblasts. Mutat Res 1978; 49:305-12. [PMID: 634305 DOI: 10.1016/0027-5107(78)90103-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
At doses varying from 8 x 10(-5) to 3 x 10(-3) M sodium selenite (Na2SeO3) induced DNA fragmentation, DNA-repair synthesis, chromosome aberrations and a mitotic inhibition in cultured human fibroblasts. The response of DNA repair-deficient xeroderma pigmentosum (XP) fibroblasts to selenite is comparable to that of control cells. Incubation with mouse liver S-9 microsomal fraction increased the capacity of selenite to induce chromosome aberrations, DNA-repair synthesis and a lethal effect. XP cells behaved as control cells when treated with activated selenite. Sodium selenate (Na2SeO4) at doses ranging from 8 x 10(-5) to 3 x 10(-3) M could not be activated by incubating with a S-9 preparation. Selenate had the capacity to induce a small but significant DNA-repair synthesis.
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Lo LW, Stich HF. The use of short-term tests to measure the preventive action of reducing agents on formation and activation of carcinogenic nitroso compounds. Mutat Res 1978; 57:57-67. [PMID: 642968 DOI: 10.1016/0027-5107(78)90234-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The effect of reducing agents on the nitrosation of methylguanidine (MG) and on the in vitro activation of dimethylnitrosamine (DMN) was examined by measuring DNA-repair synthesis (unscheduled incorporation of [3h]TdR), shifts in alkaline sucrose gradients, frequency of chromosome aberrations, and clone-forming capacity of cultured human fibroblasts. The reducing agents examined were sodium ascorbate, cysteine, cysteamine, and propyl gallate. Since the short-term bioassays used can be quantitated, it has become relatively easy to detect the inhibitory action of reducing compounds on the nitrosation reaction of MG and metabolic activation (with S-9 preparation) of the precarcinogen DMN, to measure their effective dose range, and to establish the most effective ratios between inhibitory agent and reactant. The results indicate that DNA-repair synthesis is a suitable short-term test for studying the numerous combinations and premutations between several carcinogenic or non-carcinogenic agents, and for estimating the capacity of inhibitory agents to affect formation and activation of chemical carcinogens.
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Stich HF, Lam P, Lo LW, Koropatnick DJ, San RH. The search for relevant short term bioassays for chemical carcinogens: the tribulation of a modern Sisyphus. Can J Genet Cytol 1975; 17:471-91. [PMID: 812599 DOI: 10.1139/g75-062] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Based on a good correlation between carcinogenicity and mutagenic activity several rapid microbial bioassays for chemical carcinogens have been recently developed. We would like to suggest, that these microbial tests should be followed by bioassays using cultured human cells of the "average" man, and of persons with elevated cancer risk or increased susceptibility to carcinogenic agents. The main objective of using DNA repair (unscheduled uptake of 3HTdR) and DNA fragmentation (shift in sedimentation profiles) of cultured human cells was to design a test system that can simulate conditions found in man and thus provide information relevant to the human population. A trial on 98 different carcinogens, precarcinogens and noncarcinogens showed the suitability of DNA repair synthesis as a rapid, economic and relevant assay for detection of chemical carcinogens. To check the adaptability of DNA repair synthesis of human cells as a bioassay for chemical carcinogens we examined carcinogenic nitrosation products which are formed from the interaction of nitrite and nitrosatable compounds, carcinogenic or mutagenic photosensitizing chemicals, and the effect of complex interactions. Organotropic carcinogens can be detected by measuring DNA fragmentation and DNA repair in various target organs following the in vivo application of chemical carcinogens. The pros and cons of several bioassays and their usefulness in judging a carcinogenic or mutagenic hazard to human populations is discussed.
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Lo LW, Stich HF. DNA damage, DNA repair and chromosome aberrations of xeroderma pigmentosum cells and controls following exposure to nitrosation products of methylguanidine. Mutat Res 1975; 30:397-406. [PMID: 1202330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Nitrosation of methylguanidine (MG) led to products that caused DNA fragmentation (shift in sedimentation profiles of velocity centrifugation through alkaline sucrose gradients), a DNA repair synthesis (unscheduled uptake of (3H]TdR), chromosome aberrations and a lethal effect of cultured human fibroblasts. The response of repair-deficient xeroderma pigmentosum cells did not differ from that of controls. The nitrosation of MG must be carried out at a pH level below 3, in order to obtain products that react with cellular DNA. The results show that a DNA repair synthesis of human fibroblasts appears to be a sensitive assay for carcinogenic and mutagenic nitrosation products which may be formed within an organism from non-carcinogenic compounds.
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Puszkin E, Puszkin S, Lo LW, Tanenbaum SW. Binding of cytochalasin D to platelet and muscle myosin. J Biol Chem 1973; 248:7754-61. [PMID: 4270769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Cohen SG, Lo LW. On the active site of alpha-chymotrypsin. Cyclized and noncyclized substrates with tetrasubstituted alpha carbon atoms. J Biol Chem 1970; 245:5718-27. [PMID: 5472368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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