The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Denis C. Shields - One of the best experts on this subject based on the ideXlab platform.
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Thermolabile MTHFR genotype and retinal vascular occlusive disease.
The British journal of ophthalmology, 2001Co-Authors: Mark Cahill, M Karabatzaki, C Donoghue, Raymond Meleady, L. Mynett-johnson, David J. Mooney, I M Graham, Alexander S. Whitehead, Denis C. ShieldsAbstract:Background—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A Thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between Thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined. Methods—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the Thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for Thermolabile MTHFR genotype (TT),raised tHcy levels,and risk of retinal vascular occlusive disease was examined. Results—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p
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Thermolabile mthfr genotype and retinal vascular occlusive disease
British Journal of Ophthalmology, 2001Co-Authors: Mark Cahill, M Karabatzaki, C Donoghue, Raymond Meleady, David J. Mooney, I M Graham, Alexander S. Whitehead, L Mynettjohnson, Denis C. ShieldsAbstract:Background—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A Thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between Thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined. Methods—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the Thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for Thermolabile MTHFR genotype (TT),raised tHcy levels,and risk of retinal vascular occlusive disease was examined. Results—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p<0.0001). Overall, and in both the cases and controls, the frequency of the TT genotype was higher in those with normal tHcy levels than in those with increased levels of tHcy. However, the TT genotype did not significantly alter the risk of increased tHcy levels in these patients. Conclusions—The TT genotype is not associated with an increased risk of retinal vascular occlusive disease or increased tHcy levels in this group of elderly patients. In older patients, nutritional rather than genetic factors may be more important in increasing tHcy levels, a known risk factor for retinal vascular occlusive disease. (Br J Ophthalmol 2001;85:88‐90)
Gennadii B. Zavilgelsky - One of the best experts on this subject based on the ideXlab platform.
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Folding and refolding of Thermolabile and thermostable bacterial luciferases: the role of DnaKJ heat-shock proteins
FEBS Letters, 1999Co-Authors: Ilia V Manukhov, Gennadii E Eroshnikov, Mikhail Yu. Vyssokikh, Gennadii B. ZavilgelskyAbstract:Bacterial luciferases are highly suitable test substrates for the analysis of refolding of misfolded proteins, as they are structurally labile and loose activity at 42°C. Heat-denatured Thermolabile Vibrio fischeri luciferase and thermostable Photorhabdus luminescens luciferase were used as substrates. We found that their reactivation requires the activity of the DnaK chaperone system. The DnaKJ chaperones were dispensable in vivo for de novo folding at 30°C of the luciferase, but essential for refolding after a heat-shock. The rate and yield of DnaKJ refolding of the P. luminescens thermostable luciferase were to a marked degree lower as compared with the V. fischeri Thermolabile luciferase. The refolding activity of the DnaKJ chaperones was examined at various temperatures. Between 30 and 37°C, the refolding rates of the V. fischeri luciferase decreased and the reaction reached a complete arrest at temperatures above 40°C. The rate of DnaKJ-mediated refolding of the thermostable luciferase at first increased between 30 and 37°C and then decreased at the range of 37–44°C. We observed that the rate of DnaKJ-mediated refolding of the heat-denatured P. luminescens thermostable luciferase, but not of the Thermolabile V. fischeri luciferase, decreased during the prolonged incubation at a high (47°C) temperature. The efficiency and reversibility of protein refolding arrest during and after heat-shock strongly depended on the stability of the DnaKJ-denatured luciferase complex. It is supposed that the thermostable luciferase is released during the heat-shock, whereas the Thermolabile luciferase remained bound to the chaperone.
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Folding and refolding of Thermolabile and thermostable bacterial luciferases: the role of DnaKJ heat-shock proteins.
FEBS letters, 1999Co-Authors: Ilia V Manukhov, Gennadii E Eroshnikov, Mikhail Yu. Vyssokikh, Gennadii B. ZavilgelskyAbstract:Bacterial luciferases are highly suitable test substrates for the analysis of refolding of misfolded proteins, as they are structurally labile and loose activity at 42 degrees C. Heat-denatured Thermolabile Vibrio fischeri luciferase and thermostable Photorhabdus luminescens luciferase were used as substrates. We found that their reactivation requires the activity of the DnaK chaperone system. The DnaKJ chaperones were dispensable in vivo for de novo folding at 30 degrees C of the luciferase, but essential for refolding after a heat-shock. The rate and yield of DnaKJ refolding of the P. luminescens thermostable luciferase were to a marked degree lower as compared with the V. fischeri Thermolabile luciferase. The refolding activity of the DnaKJ chaperones was examined at various temperatures. Between 30 and 37 degrees C, the refolding rates of the V. fischeri luciferase decreased and the reaction reached a complete arrest at temperatures above 40 degrees C. The rate of DnaKJ-mediated refolding of the thermostable luciferase at first increased between 30 and 37 degrees C and then decreased at the range of 37-44 degrees C. We observed that the rate of DnaKJ-mediated refolding of the heat-denatured P. luminescens thermostable luciferase, but not of the Thermolabile V. fischeri luciferase, decreased during the prolonged incubation at a high (47 degrees C) temperature. The efficiency and reversibility of protein refolding arrest during and after heat-shock strongly depended on the stability of the DnaKJ-denatured luciferase complex. It is supposed that the thermostable luciferase is released during the heat-shock, whereas the Thermolabile luciferase remained bound to the chaperone.
Jorg Sander - One of the best experts on this subject based on the ideXlab platform.
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Organomolybdän‐ und Organowolfram‐Reagenzien, II. über den carbonylolefinierenden μ‐Methylenkomplex aus Mo2Cl10 und vier äquivalenten Methyllithium
Chemische Berichte, 1992Co-Authors: Thomas Kauffmann, Petra Fiegenbaum, Michael Papenberg, Raphael Wieschollek, Jorg SanderAbstract:Organomolybdenum and Organotungsten Reagents, II. — On the Carbonyl-Olefinating μ-Methylene Complex from Mo2Cl10 and Four Equivalents of Methyllithium Mo2Cl10 reacts at — 70°C with 4 equivalents of methyllithium to give a methylated Thermolabile molybdenum complex. At higher temperatures it forms a Thermolabile carbonyl-olefinating reagent which according to NMR data is the μ-CH2 complex Cl3Mo(μ-CH2)2MoCl3 (2). Reactions of 2 with aldehydes, ketones, azomethines, and epoxides are described.
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organomolybdan und organowolfram reagenzien ii uber den carbonylolefinierenden μ methylenkomplex aus mo2cl10 und vier aquivalenten methyllithium
Chemische Berichte, 1992Co-Authors: Thomas Kauffmann, Petra Fiegenbaum, Michael Papenberg, Raphael Wieschollek, Jorg SanderAbstract:Organomolybdenum and Organotungsten Reagents, II. — On the Carbonyl-Olefinating μ-Methylene Complex from Mo2Cl10 and Four Equivalents of Methyllithium Mo2Cl10 reacts at — 70°C with 4 equivalents of methyllithium to give a methylated Thermolabile molybdenum complex. At higher temperatures it forms a Thermolabile carbonyl-olefinating reagent which according to NMR data is the μ-CH2 complex Cl3Mo(μ-CH2)2MoCl3 (2). Reactions of 2 with aldehydes, ketones, azomethines, and epoxides are described.
Alexander S. Whitehead - One of the best experts on this subject based on the ideXlab platform.
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Thermolabile MTHFR genotype and retinal vascular occlusive disease.
The British journal of ophthalmology, 2001Co-Authors: Mark Cahill, M Karabatzaki, C Donoghue, Raymond Meleady, L. Mynett-johnson, David J. Mooney, I M Graham, Alexander S. Whitehead, Denis C. ShieldsAbstract:Background—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A Thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between Thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined. Methods—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the Thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for Thermolabile MTHFR genotype (TT),raised tHcy levels,and risk of retinal vascular occlusive disease was examined. Results—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p
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Thermolabile mthfr genotype and retinal vascular occlusive disease
British Journal of Ophthalmology, 2001Co-Authors: Mark Cahill, M Karabatzaki, C Donoghue, Raymond Meleady, David J. Mooney, I M Graham, Alexander S. Whitehead, L Mynettjohnson, Denis C. ShieldsAbstract:Background—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A Thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between Thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined. Methods—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the Thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for Thermolabile MTHFR genotype (TT),raised tHcy levels,and risk of retinal vascular occlusive disease was examined. Results—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p<0.0001). Overall, and in both the cases and controls, the frequency of the TT genotype was higher in those with normal tHcy levels than in those with increased levels of tHcy. However, the TT genotype did not significantly alter the risk of increased tHcy levels in these patients. Conclusions—The TT genotype is not associated with an increased risk of retinal vascular occlusive disease or increased tHcy levels in this group of elderly patients. In older patients, nutritional rather than genetic factors may be more important in increasing tHcy levels, a known risk factor for retinal vascular occlusive disease. (Br J Ophthalmol 2001;85:88‐90)
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Prospective Evaluation of the Risk Conferred by Factor V Leiden and Thermolabile Methylenetetrahydrofolate Reductase Polymorphisms in Pregnancy
Arteriosclerosis thrombosis and vascular biology, 2000Co-Authors: Ronan P. Murphy, Alexander S. Whitehead, Catherine Donoghue, Ruth J. Nallen, Melwyn D’mello, Carmen Regan, Desmond J. FitzgeraldAbstract:Abstract —Factor V (FV) Leiden and Thermolabile methylenetetrahydrofolate reductase (MTHFR) are 2 common polymorphisms that have been implicated in vascular thrombosis. We determined whether these mutations predicted an adverse outcome in pregnancy. Second, we looked for an interaction between these 2 mutations in patients with recurrent fetal loss or thrombosis in pregnancy. Primigravid subjects at their booking visit to the National Maternity Hospital (Holles Street, Dublin, Ireland) were screened for the polymorphisms. Thermolabile MTHFR and FV Leiden genotypes were detected by either restriction fragment length polymorphism or heteroduplex capillary chromatography. The carrier frequency of FV Leiden in the screened primigravid population was 2.7% (allele frequency 1.36%), all being heterozygous for the mutation. This value was lower than expected from previous studies in European populations. Forty-nine percent of the screened population (289 of 584) were heterozygous for Thermolabile MTHFR, and 10.6% were homozygous (62 of 584). The frequency of the 2 polymorphisms was no higher in those who subsequently developed preeclampsia (n=12) or intrauterine growth retardation (n=9), and none of the screened population developed thrombosis. However, the frequency of FV Leiden was higher in patients who subsequently miscarried after the first trimester of pregnancy (allele frequency of 5.5%, P =0.0356). Among those positive for FV Leiden, 3 of 27 miscarried, compared with 24 of 572 of FV Leiden–negative patients (11% versus 4.2%). No interaction was found between the 2 mutations in the control or patient populations. In patients with a prior history of venous thrombosis, the carrier rate of FV Leiden was increased (4 of 33, allele frequency of 7.6%, P =0.0115). In contrast, the carrier frequency for Thermolabile MTHFR was no higher, and there was no interaction between the 2 mutations. Neither mutation occurred at a significantly higher frequency in patients with a prior history of recurrent fetal loss. In conclusion, FV Leiden is a risk factor for thrombosis in pregnancy and possibly for second-trimester miscarriage independent of Thermolabile MTHFR. However, prospective analysis suggests that the risk conferred by FV Leiden is low in a primigravid population. The Thermolabile MTHFR genotype was not implicated in any adverse outcome.
Mark Cahill - One of the best experts on this subject based on the ideXlab platform.
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Thermolabile MTHFR genotype and retinal vascular occlusive disease.
The British journal of ophthalmology, 2001Co-Authors: Mark Cahill, M Karabatzaki, C Donoghue, Raymond Meleady, L. Mynett-johnson, David J. Mooney, I M Graham, Alexander S. Whitehead, Denis C. ShieldsAbstract:Background—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A Thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between Thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined. Methods—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the Thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for Thermolabile MTHFR genotype (TT),raised tHcy levels,and risk of retinal vascular occlusive disease was examined. Results—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p
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Thermolabile mthfr genotype and retinal vascular occlusive disease
British Journal of Ophthalmology, 2001Co-Authors: Mark Cahill, M Karabatzaki, C Donoghue, Raymond Meleady, David J. Mooney, I M Graham, Alexander S. Whitehead, L Mynettjohnson, Denis C. ShieldsAbstract:Background—Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A Thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between Thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined. Methods—A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the Thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for Thermolabile MTHFR genotype (TT),raised tHcy levels,and risk of retinal vascular occlusive disease was examined. Results—87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p<0.0001). Overall, and in both the cases and controls, the frequency of the TT genotype was higher in those with normal tHcy levels than in those with increased levels of tHcy. However, the TT genotype did not significantly alter the risk of increased tHcy levels in these patients. Conclusions—The TT genotype is not associated with an increased risk of retinal vascular occlusive disease or increased tHcy levels in this group of elderly patients. In older patients, nutritional rather than genetic factors may be more important in increasing tHcy levels, a known risk factor for retinal vascular occlusive disease. (Br J Ophthalmol 2001;85:88‐90)
