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1.
QJM ; 2024 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-38492561

RESUMO

BACKGROUND: Kimura's disease (KD) is a rare chronic inflammatory condition characterized by nodules and lymphadenopathy in the head and neck region, exhibiting type II inflammation. Dupilumab is commonly used against type II inflammation. AIM: To evaluate the efficacy and safety of dupilumab in KD patients. DESIGN: The real-world study was conducted in a hospital in China. METHODS: Six male patients with a mean age of 24.50 ± 15.47 years were treated with dupilumab following the same protocol as that for atopic dermatitis (AD). Clinical and laboratory indicators, such as maximum nodule diameter, blood eosinophil count, eosinophil percentage, and total serum IgE levels were assessed at baseline, week 12, and week 24. Adverse events were documented. Paired t-tests and one-way ANOVA were used for statistical analysis. RESULTS: The results showed significant reductions in the longest nodule diameter at week 12 (P = 0.008) and week 24 (P = 0.001) compared to baseline. Blood eosinophil count decreased by 57.95% (P = 0.024) at week 12 and 90.59% (P = 0.030) at week 24. Eosinophil percentage decreased by 58.44% (P = 0.026) at week 12 and 89.37% (P = 0.013) at week 24. Total serum IgE levels decreased by 78.02% (P = 0.040) at week 12 and 89.55% (P = 0.031) at week 24. The presence of AD did not affect the results. One patient experienced temporary facial erythema after 32 weeks of treatment, which resolved with topical treatment. No other adverse events were reported. CONCLUSION: Dupilumab demonstrated effectiveness in treating KD without severe adverse events.

2.
Zhonghua Yi Xue Za Zhi ; 96(31): 2498-501, 2016 Aug 16.
Artigo em Chinês | MEDLINE | ID: mdl-27562050

RESUMO

OBJECTIVE: To analyze the role of oxycodone in acute lung injury(ALI) induced by lipopolysaccharide (LPS) in rats. METHODS: Male SD rats were randomly allocated into 4 groups: control group, oxycodone group, LPS group, LPS+ oxycodone group. The effects of oxycodone on LPS-induced neutrophils influx, inflammatory cytokines release, pulmonary edema, apoptotic cell were examined. In addition, the toll-like receptor 4 (TLR4) in lung tissues was detected by Western blotting. RESULTS: Oxycodone significantly attenuated LPS-induced pulmonary histopathologic changes, alveolar hemorrhage, and neutrophil infiltration. The lung wet-to-dry weight ratio, was markedly decreased by oxycodone(5.60±0.24 vs 6.80±0.27, P<0.05 ). Moreover, oxycodone decreased the productions of the inflammatory cytokines including IL-1ß, TNF-α, HMGB-1((1 208±18)pg/ml, (1 660±14) pg/ml, (61±4) pg/ml , all P<0.05). Oxycodone treatment also reduced the concentration of apoptosis in lung tissues(18.6%±0.5%, P<0.05). Furthermore, the expression of TLR4 was significantly suppressed by oxycodone treatment in lung tissues(1.20±0.15, P<0.05). CONCLUSIONS: Oxycodone exerts protective effects on LPS-induced ALI in rats. The potential mechanism of this action may attribute partly to the inhibition of TLR4 activation.


Assuntos
Lesão Pulmonar Aguda , Animais , Citocinas , Inflamação , Lipopolissacarídeos , Pulmão , Masculino , Neutrófilos , Oxicodona , Ratos , Ratos Sprague-Dawley , Receptor 4 Toll-Like
4.
Sheng Wu Gong Cheng Xue Bao ; 16(2): 235-7, 2000 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-10976336

RESUMO

Enzymatic glycerolysis of palm oil was studied in solid state with a lipase from Pseudomonus fluorescens as catalyst. The influences of molar ratio of glycerol to oil, reaction temperatures and temperature control on the accumulation of monoglyceriods in reaction mixtures were investigated. The suitable initial reaction temperature should be the minimum co-melting point of reactants. The monoglycerides contents in equilibrium state were approximately 30% at 48 degrees C or higher. An increment of 13% of monoglycerides content was obtained under the optimum temperature programming comparing with the normal equilibrium state.


Assuntos
Glicerol/metabolismo , Lipase/metabolismo , Óleos de Plantas/metabolismo , Óleo de Palmeira , Temperatura
5.
J Nutr Biochem ; 11(6): 341-7, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11002131

RESUMO

Twenty-one pregnant women living in Xichang County, China, a selenium-deficient area, were divided into two groups and given either a placebo (n = 10) as yeast or selenium-enriched yeast tablets (n = 11) to provide 100 microg selenium per day. This supplementation was begun the last trimester of pregnancy and continued for 3 months after parturition. Plasma selenium levels and glutathione peroxidase (GPX) activity steadily declined in supplemented women, but a curvilinear response occurred in milk selenium and GPX activity in both supplemented and deficient women and in plasma selenium and GPX activity in deficient women. The milk selenium levels were higher in supplemented women but there were no differences in the milk GPX activity between the two groups of women. The plasma alpha-tocopherol concentrations declined after parturition in both groups but no differences were found between the two groups of women. Plasma thiobarbituric acid reactive substances declined in supplemented women but showed a curvilinear response in unsupplemented women, suggesting peroxidative stress in these women. GPX, selenium, and peroxidative responses in plasma and milk following parturition is advocated as a new method to assess selenium status of lactating women.

6.
J Trace Elem Med Biol ; 12(1): 8-15, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9638607

RESUMO

The distribution of selenium between the plasma fractions was investigated in guinea pigs fed various levels (basal, 0.5, 1.0, 2.0, 4.0, 6.0 and 8.0 mg Se/kg) of dietary selenomethionine (Semet) and in humans living in different areas of China with different selenium status. There was a corresponding increase of selenium concentration in liver, kidney, brain, testis, spleen, heart and muscle with each increase of dietary selenium, but there were no increases of glutathione peroxidase (GPX) activity in liver, brain, testis, heart or muscle in pigs fed any of the selenium levels as compared to controls fed a basal commercial diet. On a percentage distribution basis, the selenium in selenoprotein P decreased and that in the albumin fraction increased with increased dietary intakes of selenium as Semet. The ratios of selenium to albumin in either the plasma or the albumin fractions increased with each increase in dietary selenium. The greatest percentage of selenium was in the albumin fraction of Chinese living in the high selenium areas whereas the greatest amount was in the selenoprotein P fraction in subjects living in deficient and adequate areas of China. Increases in the ratios of selenium to albumin in either the plasma or the albumin fraction also occurred with increases of selenium intake of these subjects. The results indicate that the distribution of selenium in plasma fractions reflect the levels of dietary intakes of Semet.


Assuntos
Selênio/administração & dosagem , Selênio/sangue , Adulto , Animais , Biomarcadores , Dieta , Suplementos Nutricionais , Relação Dose-Resposta a Droga , Feminino , Glutationa Peroxidase/sangue , Cobaias , Humanos , Masculino , Selênio/toxicidade , Albumina Sérica/metabolismo , Distribuição Tecidual
7.
Sheng Li Ke Xue Jin Zhan ; 29(1): 29-34, 1998 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-12501700

RESUMO

Selenium is an essential trace element for animals and humans. Selenium exerts its biological function largely through selenoproteins. Up to now nine selenoproteins' cDNAs have been cloned and sequenced, which are cellular glutathione peroxidase (cGPX), extracellular glutathine peroxidase(eGPX), phospholipid hydroperoxidase glutathione peroxidase(PHGPX), gastrointestinal glutathione peroxidase (GPX-GI), type I iodothyronine 5'-deiodinase (ID I), type 2 iodothyronine 5'-deiodinase(ID II), type III iodothyronine 5-deiodinase(ID III), selenoprotein P (Se-P) and selenoprotein W. In all these selenoproteins Se is incorporated into the protein molecule via the selenocysteinyl-tRNA which recognizes the specific UGA codons in mRNA to insert selenocysteine into the primary structure of selenoproteins.


Assuntos
Biossíntese de Proteínas , Selênio , Animais , Glutationa Peroxidase/biossíntese , Glutationa Peroxidase/genética , Humanos , Fosfolipídeo Hidroperóxido Glutationa Peroxidase , Proteínas/genética , RNA Mensageiro/genética , Selenoproteína P , Selenoproteína W , Selenoproteínas
8.
Br J Nutr ; 78(4): 671-6, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9389891

RESUMO

Weanling Wistar rats were fed on diets prepared from grain from areas deficient in I and Se where Keshan disease in endemic. Rats were divided into four groups, each of twelve rats, and received a diet supplemented with: I, Se, I + Se or nothing. At 8 weeks after weaning, myocardial alpha-glycerophosphate dehydrogenase (EC 1.1.1.8; alpha-GPD) activity and indices of Se and thyroid hormone status were determined. The group supplemented with iodine had increased plasma thyroxine levels. There was no difference in plasma triiodothyronine concentration between the groups but triiodothyronine levels in heart were reduced in the Se-supplemented group. Se supplementation increased myocardial glutathione peroxidase activity (EC 1.11.1.9) and the type I 5'-deiodinase (EC 3.8.1.4) activity in rat liver, but no type I 5'-deiodinase activity was detected in heart. alpha-GDP activity in heart was increased in group supplemented with Se, I or both. There was a significant relationship (P < 0.05) between myocardial alpha-GDP activity and plasma thyroxine levels but not between alpha-GDP and myocardial glutathione peroxidase activity. The results indicate that iodine may be more important than Se in energy metabolism in the myocardium, which may give a new insight for the study of the aetiology of Keshan disease in areas where foodstuffs are deficient in both Se and I.


Assuntos
Cardiomiopatias/etiologia , Glicerolfosfato Desidrogenase/metabolismo , Iodo/deficiência , Miocárdio/metabolismo , Selênio/deficiência , Hormônios Tireóideos/metabolismo , Análise de Variância , Animais , Cardiomiopatias/enzimologia , Cardiomiopatias/metabolismo , Metabolismo Energético , Iodo/administração & dosagem , Fígado/enzimologia , Fígado/metabolismo , Masculino , Modelos Biológicos , Miocárdio/enzimologia , Ratos , Ratos Wistar , Selênio/administração & dosagem , Hormônios Tireóideos/sangue , Tiroxina/sangue , Tiroxina/metabolismo , Tri-Iodotironina/sangue , Tri-Iodotironina/metabolismo , Desmame
9.
Wei Sheng Yan Jiu ; 26(1): 56-9, 1997 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-15747464

RESUMO

Selenomethionine (SeMet) reacted with cyanogen bromide (BrCN) quantitatively forms CH3SeCN. After extracted with CHCl3, the Se of CH3SeCN is acid-digested to Se(IV). Then 2,3-diaminonaphthalene is used to determine the fluorescent Se value of 4,5-benzopiaselenol. The determination limit of this method was 3 ng/g SeMet. The accuracy of 10-500 ng Se in SeMet standard was 91.8%-97.6%. RSD was 1.9%-6.3%. Recoveries for grain and blood were 92.3%-96.7%. RSD was 2.7%-5.1%. The RSD for samples was 2.7%-9.0%. Selenocystine, selenocystiene selenite and methionine did not interfere with the determination.


Assuntos
Grão Comestível/química , Fluorometria/métodos , Selênio/análise , Selenometionina/sangue , Brometo de Cianogênio/química , Cistina/análogos & derivados , Humanos , Metionina , Compostos Organosselênicos , Selênio/sangue , Selenometionina/análise
10.
Inorg Chem ; 36(21): 4804-4811, 1997 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-11670160

RESUMO

The complex anion bis(azido)(tetraphenylporphinato)ferrate(III) has been synthesized and characterized by variable-temperature X-ray structure determinations, powder and single-crystal EPR, IR, and Mössbauer spectroscopy, and magnetic susceptibility measurements. The synthesis utilizes 18-crown-6 to solubilize sodium azide in the synthetic procedure. All physical data for [Na(18C6)(H(2)O)(2)][Fe(TPP)(N(3))(2)].2C(6)H(5)Cl are consistent with a thermal spin-equilibrium system: low spin (S = (1)/(2)) right harpoon over left harpoon high spin (S = (5)/(2)). Structure determinations at 130 and 293 K show equatorial and axial Fe-N bond elongation at 293 K. Fe-N(p) = 1.9991(11) Å, Fe-N(az) = 1.9734(14) Å at 130 K, and Fe-N(p) = 2.010(4) Å, Fe-N(az) = 1.998(2) Å at 293 K. The EPR g values for a powder sample at 4.2 K are 1.81, 2.18, and 2.70. A fit of the powder EPR spectrum at 4.2 K with a crystal field model that allows quartet and sextet admixtures suggests that the first sextet state is approximately 655 cm(-)(1) above the ground doublet. Single-crystal EPR data indicate that the largest g value occurs at an angle of 56 degrees from the porphyrin normal and at 35 and 81 degrees from the Fe-N(p) vectors. The asymmetric azide IR absorption bands at 2014 and 2036 cm(-)(1) can be assigned to low- and high-spin species, respectively, and display temperature-dependent intensities. The Mössbauer experiments reveal a gradual decrease in the quadrupole splitting as the temperature increases from 140 to 300 K. The magnetic susceptibility measurements show a gradual increase of &mgr;(eff) with temperature. Crystal data for [Na(18C6)(H(2)O)(2)][Fe(TPP)(N(3))(2)].2C(6)H(5)Cl (130 K): a = 11.417(2) Å, b = 12.371(4) Å, c = 12.628(2) Å, alpha = 64.30(2) degrees, beta = 77.18(3) degrees, gamma = 77.67(2) degrees, triclinic, space group P&onemacr;, Z = 1. Crystal data (293 K): a = 11.7652(12) Å, b = 12.6488(6) Å, c = 12.8608(13) Å, alpha = 62.02(2) degrees, beta = 75.996(7) degrees, gamma = 75.465(9) degrees.

11.
Proc Natl Acad Sci U S A ; 93(23): 12791-8, 1996 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-8917498

RESUMO

We have used Mössbauer and electron paramagnetic resonance (EPR) spectroscopy to study a heme-N-alkylated derivative of chloroperoxidase (CPO) prepared by mechanism-based inactivation with allylbenzene and hydrogen peroxide. The freshly prepared inactivated enzyme ("green CPO") displayed a nearly pure low-spin ferric EPR signal with g = 1.94, 2.15, 2.31. The Mössbauer spectrum of the same species recorded at 4.2 K showed magnetic hyperfine splittings, which could be simulated in terms of a spin Hamiltonian with a complete set of hyperfine parameters in the slow spin fluctuation limit. The EPR spectrum of green CPO was simulated using a three-term crystal field model including g-strain. The best-fit parameters implied a very strong octahedral field in which the three 2T2 levels of the (3d)5 configuration in green CPO were lowest in energy, followed by a quartet. In native CPO, the 6A1 states follow the 2T2 ground state doublet. The alkene-mediated inactivation of CPO is spontaneously reversible. Warming of a sample of green CPO to 22 degrees C for increasing times before freezing revealed slow conversion of the novel EPR species to two further spin S = 1/2 ferric species. One of these species displayed g = 1.82, 2.25, 2.60 indistinguishable from native CPO. By subtracting spectral components due to native and green CPO, a third species with g = 1.86, 2.24, 2.50 could be generated. The EPR spectrum of this "quasi-native CPO," which appears at intermediate times during the reactivation, was simulated using best-fit parameters similar to those used for native CPO.


Assuntos
Compostos Alílicos/farmacologia , Derivados de Benzeno/farmacologia , Cloreto Peroxidase/antagonistas & inibidores , Cloreto Peroxidase/química , Cloreto Peroxidase/isolamento & purificação , Espectroscopia de Ressonância de Spin Eletrônica , Inibidores Enzimáticos/farmacologia , Peróxido de Hidrogênio/farmacologia , Fungos Mitospóricos/enzimologia , Porfirinas , Espectroscopia de Mossbauer
12.
Biomed Environ Sci ; 8(3): 187-201, 1995 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8561918

RESUMO

The human dietary selenium requirement in China has been estimated by various methods. The minimum dietary selenium requirement for the prevention of Keshan disease (KD) was found to be around 17 micrograms/d. On the other hand, an intake of 40 micrograms/d is required to maintain the plasma glutathione peroxidase (GPx) activity at plateau. Hence 40 micrograms/d is considered as the adequate dietary selenium requirement. Studies conducted in a chronic selenosis area indicate that the toxic dietary selenium intake (adverse effect level), which would maintain the characteristic fingernail changes, was approximately 1600 micrograms/d. The mean value of dietary selenium intakes, which enabled the five patients to recover from fingernail lesions, was found to be 819 +/- 126 micrograms/d. At a 95% confidence limit, the lower limit is around 600 micrograms/d. Therefore, 600 and 400 micrograms/d were suggested as the individual daily maximum safe selenium intake and the safe dietary selenium intake, respectively. The results were used in the prevention of Se-related endemic KD and Kashin-Beck disease (KBD).


Assuntos
Cardiomiopatia Dilatada/prevenção & controle , Deficiências Nutricionais/prevenção & controle , Selênio/administração & dosagem , Cardiomiopatia Dilatada/epidemiologia , Cardiomiopatia Dilatada/etiologia , China/epidemiologia , Deficiências Nutricionais/complicações , Deficiências Nutricionais/epidemiologia , Humanos , Necessidades Nutricionais , Selênio/sangue , Selênio/deficiência , Selênio/toxicidade , Selênio/urina
13.
Sheng Li Ke Xue Jin Zhan ; 26(1): 12-6, 1995 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-7604216

RESUMO

Type I 5'-deiodinase is a Se-containing enzyme. If Se is deficient, the deiodinase activity would be inhibited, the level of circulation T4 will be elevated, and the concentration T3 in peripheral tissues will be decreased. Se deficiency will also accelerate the iodine depletion of thyroid and may even exacerbate some detrimental effects of iodine deficiency. Possibly Se deficiency is involved in the occurrence and development of iodine deficient disorders. Keshan disease, with Se deficiency as the major cause, was also observed a change of thyroid hormone metabolism. The change of respiratory enzyme activities in myocardium of Keshan disease is in the way somewhat like that of hypothyroidism caused by iodine deficiency. The metabolic change of thyroid hormone after Se deficiency or iodine deficiency may be related to the occurrence of Keshan disease.


Assuntos
Selênio/deficiência , Hormônios Tireóideos/metabolismo , Animais , Deficiências Nutricionais/sangue , Deficiências Nutricionais/enzimologia , Humanos , Iodeto Peroxidase/classificação , Iodeto Peroxidase/metabolismo , Iodo/deficiência , Tiroxina/sangue , Tri-Iodotironina/sangue
14.
Biochim Biophys Acta ; 1122(3): 293-8, 1992 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-1504090

RESUMO

A recent report from this laboratory (Zhang, J.-H., Kurtz, D.M., Jr., Xia, Y.-M. and Debrunner, P.G. (1991) Biochemistry 30, 583-589) described a procedure for reconstitution of a functional di-iron site in the octameric, non-heme iron O2-carrying protein, hemerythrin by addition of ferrous salts to apoprotein, followed by slow dilution of the denaturant. Although the resulting protein contained its full complement of iron, i.e., 2 Fe per subunit, about 30% of the iron was found to remain ferrous under ambient O2, i.e., this iron was incapable of forming an O2 adduct. In this report a method is described for obtaining essentially fully functional hemerythrin by passage of the freshly reconstituted protein through an [oxy/30% non-functional----met----deoxy----oxy redox cycle. UV/vis absorption and 57Fe Mössbauer spectroscopies show that little or no non-functional iron remains in the reconstituted oxyhemerythrin after the redox cycle. Quantitations of protein and diiron sites show that, during the first step of the redox cycle, the non-functional iron is converted to a form that is spectroscopically indistinguishable from that of native methemerythrin. Far-UV circular dichroism shows that the secondary structure of this reconstituted methemerythrin is essentially identical to that of native protein. Non-denaturing polyacrylamide gel electrophoresis shows that the size and charge of the native and reconstituted proteins before and after redox cycling are essentially identical. These results indicate that the non-functional iron is converted to a functional form by the redox cycling, and that the key step in this conversion is the [oxy/30% non-functional]----met transformation.


Assuntos
Hemeritrina/química , Ferro/química , Hemeritrina/análogos & derivados , Hemeritrina/isolamento & purificação , Biologia Marinha , Oxirredução , Espectrofotometria/métodos
15.
Biochemistry ; 30(2): 583-9, 1991 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-1988045

RESUMO

The first reconstitutions of functional diiron sites in the nonheme O2-carrying proteins hemerythrin (Hr) and myohemerythrin (myoHr) have been achieved. Both proteins are reconstituted under anaerobic conditions, and the procedure consists of (i) denaturation of the native met form with 6 M guanidinium chloride in the presence of sodium dithionite and 2,2'-dipyridyl, (ii) separation of the apoprotein from the other reagents and products, (iii) addition of an iron(II) stock solution to the apoprotein in the presence of 2-mercaptoethanol, and (iv) several cycles of slow dilution and reconcentration by ultrafiltration to remove excess reagents. Iron analyses indicate that the apoproteins have been essentially completely freed of iron and that reconstituted Hr contains its full complement of iron, i.e., approximately 2 Fe/subunit. Ferrous rather than ferric iron appears to be necessary for recovery of the native structures for both myoHr and Hr. In the case of Hr, reconstitution was successful only when iron(II) was added to apoHr prior to removal of denaturant. ApoHr is essentially insoluble at pH 7 in the absence of denaturants but remains soluble when denaturant is removed in the presence of ferrous iron, which leads to recovery of the octameric structure containing all of its diiron sites. Iron(II) apparently stabilizes the native or a nearly native structure during reconstitution. OxymyoHr and oxyHr are the major initial products of reconstitution. The yield of oxymyoHr from apomyoHr was approximately 87%. In contrast to reconstituted oxymyoHr, where essentially all of the iron appears to be functional, approximately 30% of the diiron sites in the reconstituted oxyHr are unable to bind O2 at ambient p(O2).(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Hemeritrina/análogos & derivados , Hemeritrina/ultraestrutura , Ferro , Animais , Apoproteínas , Técnicas In Vitro , Invertebrados , Espectrofotometria Ultravioleta , Análise Espectral
16.
J Nutr ; 119(9): 1318-26, 1989 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2795246

RESUMO

Selenium deficiency is necessary for the development of the cardiomyopathy known as Keshan disease. Healthy boys and men (19-22 per group) from a low selenium area (Dechang County) and from an area where sodium selenite was added to salt (Mianning County) were studied. Keshan disease was endemic in Dechang but occurred rarely in Mianning. After an initial blood sampling, each subject received daily selenium supplements (100 micrograms selenium for boys and 200 micrograms for men) as sodium selenate for 14 d. Blood was sampled again at 7 and 14 d. Boys from Dechang had blood selenium levels similar to levels reported for patients with Keshan disease. Plasma glutathione peroxidase activity in boys and men from Dechang was 33 and 43%, respectively, of values from the corresponding groups in Mianning. Comparison of plasma selenium concentrations in boys and men from Dechang gave values of 33 and 38%, respectively, of the corresponding groups in Mianning. Selenium status did not affect red blood cell superoxide dismutase or catalase activities. Plasma vitamin E concentration was below the normal range in all groups but was unaffected by selenium status. Measurements of plasma malondialdehyde revealed no difference between subjects from Dechang and subjects from Mianning. Selenium supplementation raised plasma glutathione peroxidase activity and plasma selenium concentration in all groups. Groups with higher plasma selenium concentration had relatively smaller increases in glutathione peroxidase activity than in selenium concentration. These results characterize the selenium deficiency in subjects at risk for developing Keshan disease. The results obtained with supplementation of selenium indicate the presence of additional plasma forms of selenium besides glutathione peroxidase.


Assuntos
Glutationa Peroxidase/sangue , Selênio/deficiência , Adolescente , Adulto , Cardiomiopatias/etiologia , Cardiomiopatias/prevenção & controle , Criança , China , Nível de Saúde , Hematócrito , Humanos , Masculino , Selênio/sangue , Selênio/uso terapêutico , Vitamina E/sangue
17.
Zhonghua Fu Chan Ke Za Zhi ; 23(6): 377-8, 1988 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-3073924
18.
Biochemistry ; 27(3): 1014-24, 1988 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-3365363

RESUMO

Nitric oxide forms adducts with the binuclear iron site of hemerythrin (Hr) at [Fe(II),Fe(II)]deoxy and [Fe(II),Fe(III)]semimet oxidation levels. With deoxyHr our results establish that (i) NO binds reversibly, forming a complex which we label deoxyHrNO, (ii) NO forms a similar but distinct complex in the presence of fluoride, which we label deoxyHrFNO, (iii) NO is directly coordinated to one iron atom of the binuclear pair in these adducts, most likely in a bent end-on fashion, and (iv) the iron atoms in the binuclear sites of both deoxyHrNO and deoxyHrFNO are antiferromagnetically coupled, thereby generating unique electron paramagnetic resonance (EPR) detectable species. The novel EPR signal of deoxyHrNO (deoxyHrFNO) with g[[ = 2.77 (2.58) and g = 1.84 (1.80) is explained by the magnetic interaction of the Fe(II) (S' = 2) and [FeNO]7 (S = 3/2) centers observed by Mössbauer spectroscopy. Antiferromagnetic coupling leads to a ground state of Seff = 1/2. Analysis of the EPR parameters using the isotropic spin-exchange Hamiltonian, Hex = 2JS3/2.S2, and including zero-field splitting leads to a coupling constant, -J approximately 23 cm-1, for deoxyHrNO. The resonance Raman spectrum of deoxyHrNO shows features at 433 and 421 cm-1 that shift downward with 15N16O and that are assigned to stretching and bending modes, respectively, of the [FeNO]7 unit. Sensitivity of the bending mode to D2O suggests that bound NO participates in hydrogen bonding. We propose that the terminal oxygen atom of NO is hydrogen bonded to the proton of the mu-hydroxo bridge in the Fe-(OH)-Fe unit. A bent Fe-N-O geometry is supported by spectroscopic and structural comparisons to synthetic complexes and is consistent with a limiting [FeII,FeIIINO-] formulation for deoxyHrNO. Reversibility of NO binding to deoxyHr is demonstrated by bleaching of the optical and EPR spectra of deoxyHrNO upon additions of excess N3- or CNO-. DeoxyHrNO undergoes autoxidation under anaerobic conditions over the course of several hours. The product of this autoxidation appears to be an EPR-silent NO adduct of semimetHr. The formal one-electron oxidations of the binuclear iron site of deoxyHr by NO and by HNO2 can conceivably occur with no net change in charge on the iron site. In contrast, autoxidation of oxy- to metHr requires a change in net charge on the iron site, which may provide a kinetic barrier.


Assuntos
Hemeritrina/metabolismo , Metaloproteínas/metabolismo , Óxido Nítrico/metabolismo , Animais , Sítios de Ligação , Ferro/metabolismo , Cinética , Nematoides/metabolismo , Oxirredução , Ligação Proteica , Análise Espectral , Análise Espectral Raman , Termodinâmica
19.
J Nutr ; 115(6): 733-42, 1985 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-3998867

RESUMO

Selenium deficiency has been implicated as a cause of the cardiomyopathy known as Keshan disease in China. Selenium is an essential constituent of glutathione peroxidase, an enzyme that destroys hydroperoxides by using the reducing equivalents of reduced glutathione (GSH). We studied glutathione-dependent hydroperoxide metabolism in isolated perfused rat hearts. Hearts from selenium-deficient rats contained 5% of the glutathione peroxidase activity found in control hearts. Glutathione reductase activity and glutathione content were not affected by selenium deficiency. Infusion of t-butylhydroperoxide into control hearts caused an increase in heart glutathione disulfide (GSSG) concentration proportional to the rate of hydroperoxide infusion up to 200 nmol/(g heart X min). GSSG was released into the perfusate in proportion to the hydroperoxide infusion rate up to 150 nmol/(g heart X min), but GSSG release did not increase further with higher infusion rates. Thus, GSSG release by the heart is saturable. It had a maximum rate of about 14 nmol GSH equivalents/(g heart X min) when stimulated by t-butylhydroperoxide infusion. This indicates that GSSG release by the heart is carrier-mediated and is not due to passive diffusion. Infusion of hydroperoxide into selenium-deficient hearts failed to cause increases in heart GSSG concentration and in GSSG release. This indicates that selenium-deficient heart cannot metabolize hydroperoxides through glutathione-dependent pathways. We suggest that selenium deficiency might predispose the heart to injury from oxidant stress.


Assuntos
Glutationa/metabolismo , Miocárdio/metabolismo , Peróxidos/metabolismo , Selênio/deficiência , Animais , Dieta , Glutationa/análogos & derivados , Dissulfeto de Glutationa , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Glutationa Transferase/metabolismo , Cardiopatias/enzimologia , Cardiopatias/metabolismo , Masculino , Miocárdio/enzimologia , Perfusão , Peróxidos/farmacologia , Ratos , Ratos Endogâmicos , terc-Butil Hidroperóxido
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