Fe, Chlorophyll (Chl) and total nitrogen (TN) content in tissues were measured in Fe-deficient cultures of Ulva. pertusa over a period of 60 days. Photosynthetic carbon fixation rates were studied at the start of and ...Fe, Chlorophyll (Chl) and total nitrogen (TN) content in tissues were measured in Fe-deficient cultures of Ulva. pertusa over a period of 60 days. Photosynthetic carbon fixation rates were studied at the start of and 30 days after Fe-deficiency culture, when the effects of Fe-deficiency on the ultrastructure were also analyzed. The iron content in tissue decreased exponentially during Fe-deficiency (from 726.7 to 31.6 μg/gdw) and simultaneously Chl and TN content declined to 4.35% and 59.9% of their original levels respectively. Maximum carbon fixation rate (50-250 μmol/m 2 s) under Fe-deficiency decreased significantly compared with the control (p<0.01) and was 13.6 to 0.365 μg C /cm 2 h. Photosynthesis in Fe-deficient cells became light-saturated at lower irradiance than that in control. Ultrastructural observations of Fe-deficient cells showed reductions in chloroplast number, some degeneration of lamellar organization, an increase in vacuolar area, a decrease in mitochondrial matrix density, and variation in accumulation body number and morphology. During Fe-deficiency, the algae growth rate continued to decline and after 6 weeks of iron deficiency, no further growth was detectable. These suggested that the lower growth rate of Ulva. pertusa under Fe-deficiency could be due mainly to nitrogen utilization and inhibition of photosynthesis.展开更多
Objective: To determine baseline iron and oxidative status in a cohort of pregnant women before iron supplementation in our setting. Background: Screening of iron deficiency before supplementation during pregnancy has...Objective: To determine baseline iron and oxidative status in a cohort of pregnant women before iron supplementation in our setting. Background: Screening of iron deficiency before supplementation during pregnancy has been scarce. Therefore, following routine iron supplementation confounding results might be found in outcomes of groups of patients considered. Taking in account that body/serum iron status is reportedly linked to maternal oxidative status, we aimed to associate assessment of baseline iron and oxidative status of women in need of oral supplementation during pregnancy. Methods: This is a cross-sectional study concerning 74 women attending antenatal care at the University Clinics of Kinshasa from September 2017 throughout June 2018, with a singleton pregnancy not exceeding 19 weeks, regardless of age and parity. Variables of the study included sociodemographic and anthropometric ones along with parameters of iron status (hemoglobin, hematocrit, ferritin, serum iron, transferrin and iron saturation capacity). Oxidative status was assessed using superoxide dismutase (SOD) and uric acid as antioxidants, while oxidant agents were oxidized LDL and blood glucose (beside serum iron and ferritin). According to local standards anemia was defined as hemoglobin 10 g/L and pathologic serum ferritin as 15 ng/ml. For statistical calculations we used t-test, chi-square test and Pearson’s correlation test, the significance being stated at p ≤ 0.05. Results: At recruitment (15.9 ± 1.7 9 week gestational age) mean hemoglobin value of the overall study group was 10.3 ± 1.5 g/dl. Anemia was diagnosed to 39 women that represented 52.2% of the study group, most of anemic women belonging to low socioeconomic sub-group (69.2% vs 29%;P < 0.001). The majority was para 2, with average weight of 70.2 ± 14.5 Kg (P not significant between sub-groups) and BMI of 26 ± 5.2 Kg/m2 (P < 0.01). The proportion of obeses was 18.9%. The proportion of intestinal parasitosis was significantly higher among anemic women (61.5% vs 34.3%;P < 0.02) that had lower alimentary iron intake (22.8 ± 4.9 gr/day vs 31.4 ± 9.5 gr;P < 0.001). Of markers of iron status serum ferritin and iron were lower in anemic women (7.5 ± 3.9 ng/ml vs 35.7 ± 17.1 ng/ml;P < 0.001 and 52.7 ± 38.9 μg/dl vs 96.2 ± 41.8 μg/dl, respectively. Both sub-groups were similar in serum transferrin. As of markers of oxidative stress anemic women had significantly higher superoxide dismutases (SOD) (1056.4 ± 762.1 UI/L vs 682.6 ± 543.9 UI/L (P < 0.02) and oxidizedd anti LDL Ac (439.6 ± 209.5 UI/L vs 192.8 ± 136.3 UI/L (P < 0.001). Serum iron, ferritin, SOD and oxidized LDL were more likely to assess iron and oxidative status in our setting. Conclusion: The rate of anemic mothers found in our study (52.2%) has been quite constant in our setting for years, meaning endemicity. Serum iron and ferritin were significantly lower in anemic women, which is supportive of routine iron supplementation during pregnancy. Significantly higher level of SOD and oxidized LDL in anemic women suggests that maternal anemia may count into oxidative stress likely to be found in these women.展开更多
Aims: Chronic hepatitis C virus (HCV) infection is often associated with glucose metabolic disorders and iron overload. It has recently been shown that reactive oxygen species (ROS) increase gluconeogenesis in hepatoc...Aims: Chronic hepatitis C virus (HCV) infection is often associated with glucose metabolic disorders and iron overload. It has recently been shown that reactive oxygen species (ROS) increase gluconeogenesis in hepatocytes through the forkhead box-containing protein O subfamily-1 (FOXO1)-dependent pathway. The aim of this study is proving a cause-and-effect relationship between iron-mediated ROS production and insulin resistance (IR) in chronic hepatitis C (CH-C) patients. Methods: The study included 42 patients with CH-C (22 males and 20 females, median age 53 years). Homeostasis model assessment of insulin resistance (HOMA-IR) value was assessed for each patient at entry. Gene expression levels in the biopsied liver tissues were determined by quantitative reverse transcription-polymerase chain reaction (RT- PCR). In addition, the effect of ROS on gluconeogenesis was assessed using HepG2 cells treated with a well-known ROS generator, diethylmaleate (DEM). Results: The serum ferritin levels were significantly correlated with the serum aspartate aminotransferase level, alanine aminotransferase level, HOMA-IR value, grade of fatty accumulation, total hepatic iron score, and 8-OH-deoxy-2’-guanosine (8-OHdG)-positive cell count. FOXO1 expression was correlated with 8-OHdG-positive cell count, phosphoenolpyruvate carboxykinase (PEPCK) expression, and HOMA-IR. In HepG2 cells, the gene transcription of FOXO1 and PEPCK was increased by DEM treatment, which was associated with an increase in non-phosphorylated FOXO1 protein in the nuclear fraction. Conclusions: Iron-mediated ROS production enhances gluconeogenesis through the FOXO1-mediated pathway and is an affecting factor to IR in patients with CH-C.展开更多
The iron aluminides show anomalous stress peaks at temperatures of the order of 400～600 ℃, irrespective of whether the crystal structure is B2 type or DO 3 type. Such features will be examined on the basis of therma...The iron aluminides show anomalous stress peaks at temperatures of the order of 400～600 ℃, irrespective of whether the crystal structure is B2 type or DO 3 type. Such features will be examined on the basis of thermally activated dislocation processes, considering the influence of test parameters such as temperature and strain rate, and material parameters such as crystal composition and orientation. Detailed analyses of deformation modes by slip step studies, transmission electron microscopy examinations of dislocation structures, and texture studies will also be considered. Observations of dislocation structures are clearly of great interest for suggesting the possible models of deformation, but suffer from two major weaknesses: the post mortem structures in samples deformed at high temperature may not be the same as those producing plasticity; almost all possible hypotheses for strengthening can find support from such observations, since almost all imaginable dislocation configurations can be found with sufficient diligence by the researcher. Strengthening at intermediate temperatures in DO 3 and B2 ordered iron aluminides will be analysed here, making combined use of observations of deformation structures and examinations of the influence of varying the deformation parameters.展开更多
AIM: To determine the plasmatic iron content and evaluate the oxidative stress(OS) markers in subjects receiving blood therapy.METHODS: Thirty-nine individuals with unspecified anemia receiving blood transfusions and ...AIM: To determine the plasmatic iron content and evaluate the oxidative stress(OS) markers in subjects receiving blood therapy.METHODS: Thirty-nine individuals with unspecified anemia receiving blood transfusions and 15 healthy subjects were included in the study. Anemic subjects were divided into three subgrou P:(1) those that received up to five blood transfusions(n = 14);(2) those that received from five to ten transfusions(n = 11); and(3) those that received more than ten transfusions(n = 14). Blood samples were collected by venous arm puncture and stored in tubes containing heparin. The plasma and cells were separated by centrifugation and subsequently used for analyses. Statistical analyses were performed using Kruskal-Wallis analysis of variance followed by Dunn's multiple comparison tests when appropriate.RESULTS: The eletrophoretic hemoglobin profiles of the subjects included in this study indicated that no patients presented with hemoglobinopathy. Labile plasmatic iron, ferritin, protein carbonyl, thiobarbituric acidreactive substances(TBARS) and dichlorofluorescein diacetate oxidation were significantly higher(P < 0.05), whereas total thiol levels were significantly lower(P < 0.05) in transfused subjects compared to controls. Additionally, the activity of catalase, superoxide dismutase and glutathione peroxidase were significantly lower in the transfused subjects(P < 0.05). Antioxidant enzyme activities and total thiol levels were positively correlated(P < 0.05), and negatively correlated with the levels of protein carbonyl and TBARS(P < 0.05). In contrast, protein carbonyl and TBARS were positively correlated(P < 0.05). Altogether, these data confirm the involvement of OS in patients following therapy with repeated blood transfusions.CONCLUSION: Our data reveal that changes in OS markers are correlated with levels of labile plasmatic iron and ferritin and the number of transfusions.展开更多
With the increasing demand for lightweight and lower fuel consumption and safety of automobile industry, lightweight materials of high strength steel (HSS) are more and more widely used. The hot stamping technology, w...With the increasing demand for lightweight and lower fuel consumption and safety of automobile industry, lightweight materials of high strength steel (HSS) are more and more widely used. The hot stamping technology, which is determined by the inherent mechanical properties of high strength steel, makes molds prone to wear failure in the harsh service environments. In this paper, a finite element model is proposed for analyzing the value and distributions law of friction shear stress of contact surface of the pin disk. Through the simulation process of sliding wear, two kinds of different cladding materials of the pin specimens including H13 and Fe65, were experimented under three different loads by using the software ABAQUS. And then the pin-on- disk wear test at elevated temperature was conducted to verify the effectiveness of the simula-tion results. The results showed that the friction shear stress of pin with iron-based cladding and H13 steel was different under different loads, but the distribution was basically the same;the normal friction shear stress increased gradually along the direction of the pin movement, and the tangential shear stress increased gradually from the center of the pin to the outside of the circle;the value of the friction shear stress of the normal joints on the contact surface was periodically fluctuating in the whole dynamic analysis step, while it was basically stable in the tangential direction.展开更多
文摘Fe, Chlorophyll (Chl) and total nitrogen (TN) content in tissues were measured in Fe-deficient cultures of Ulva. pertusa over a period of 60 days. Photosynthetic carbon fixation rates were studied at the start of and 30 days after Fe-deficiency culture, when the effects of Fe-deficiency on the ultrastructure were also analyzed. The iron content in tissue decreased exponentially during Fe-deficiency (from 726.7 to 31.6 μg/gdw) and simultaneously Chl and TN content declined to 4.35% and 59.9% of their original levels respectively. Maximum carbon fixation rate (50-250 μmol/m 2 s) under Fe-deficiency decreased significantly compared with the control (p<0.01) and was 13.6 to 0.365 μg C /cm 2 h. Photosynthesis in Fe-deficient cells became light-saturated at lower irradiance than that in control. Ultrastructural observations of Fe-deficient cells showed reductions in chloroplast number, some degeneration of lamellar organization, an increase in vacuolar area, a decrease in mitochondrial matrix density, and variation in accumulation body number and morphology. During Fe-deficiency, the algae growth rate continued to decline and after 6 weeks of iron deficiency, no further growth was detectable. These suggested that the lower growth rate of Ulva. pertusa under Fe-deficiency could be due mainly to nitrogen utilization and inhibition of photosynthesis.
文摘Objective: To determine baseline iron and oxidative status in a cohort of pregnant women before iron supplementation in our setting. Background: Screening of iron deficiency before supplementation during pregnancy has been scarce. Therefore, following routine iron supplementation confounding results might be found in outcomes of groups of patients considered. Taking in account that body/serum iron status is reportedly linked to maternal oxidative status, we aimed to associate assessment of baseline iron and oxidative status of women in need of oral supplementation during pregnancy. Methods: This is a cross-sectional study concerning 74 women attending antenatal care at the University Clinics of Kinshasa from September 2017 throughout June 2018, with a singleton pregnancy not exceeding 19 weeks, regardless of age and parity. Variables of the study included sociodemographic and anthropometric ones along with parameters of iron status (hemoglobin, hematocrit, ferritin, serum iron, transferrin and iron saturation capacity). Oxidative status was assessed using superoxide dismutase (SOD) and uric acid as antioxidants, while oxidant agents were oxidized LDL and blood glucose (beside serum iron and ferritin). According to local standards anemia was defined as hemoglobin 10 g/L and pathologic serum ferritin as 15 ng/ml. For statistical calculations we used t-test, chi-square test and Pearson’s correlation test, the significance being stated at p ≤ 0.05. Results: At recruitment (15.9 ± 1.7 9 week gestational age) mean hemoglobin value of the overall study group was 10.3 ± 1.5 g/dl. Anemia was diagnosed to 39 women that represented 52.2% of the study group, most of anemic women belonging to low socioeconomic sub-group (69.2% vs 29%;P < 0.001). The majority was para 2, with average weight of 70.2 ± 14.5 Kg (P not significant between sub-groups) and BMI of 26 ± 5.2 Kg/m2 (P < 0.01). The proportion of obeses was 18.9%. The proportion of intestinal parasitosis was significantly higher among anemic women (61.5% vs 34.3%;P < 0.02) that had lower alimentary iron intake (22.8 ± 4.9 gr/day vs 31.4 ± 9.5 gr;P < 0.001). Of markers of iron status serum ferritin and iron were lower in anemic women (7.5 ± 3.9 ng/ml vs 35.7 ± 17.1 ng/ml;P < 0.001 and 52.7 ± 38.9 μg/dl vs 96.2 ± 41.8 μg/dl, respectively. Both sub-groups were similar in serum transferrin. As of markers of oxidative stress anemic women had significantly higher superoxide dismutases (SOD) (1056.4 ± 762.1 UI/L vs 682.6 ± 543.9 UI/L (P < 0.02) and oxidizedd anti LDL Ac (439.6 ± 209.5 UI/L vs 192.8 ± 136.3 UI/L (P < 0.001). Serum iron, ferritin, SOD and oxidized LDL were more likely to assess iron and oxidative status in our setting. Conclusion: The rate of anemic mothers found in our study (52.2%) has been quite constant in our setting for years, meaning endemicity. Serum iron and ferritin were significantly lower in anemic women, which is supportive of routine iron supplementation during pregnancy. Significantly higher level of SOD and oxidized LDL in anemic women suggests that maternal anemia may count into oxidative stress likely to be found in these women.
文摘Aims: Chronic hepatitis C virus (HCV) infection is often associated with glucose metabolic disorders and iron overload. It has recently been shown that reactive oxygen species (ROS) increase gluconeogenesis in hepatocytes through the forkhead box-containing protein O subfamily-1 (FOXO1)-dependent pathway. The aim of this study is proving a cause-and-effect relationship between iron-mediated ROS production and insulin resistance (IR) in chronic hepatitis C (CH-C) patients. Methods: The study included 42 patients with CH-C (22 males and 20 females, median age 53 years). Homeostasis model assessment of insulin resistance (HOMA-IR) value was assessed for each patient at entry. Gene expression levels in the biopsied liver tissues were determined by quantitative reverse transcription-polymerase chain reaction (RT- PCR). In addition, the effect of ROS on gluconeogenesis was assessed using HepG2 cells treated with a well-known ROS generator, diethylmaleate (DEM). Results: The serum ferritin levels were significantly correlated with the serum aspartate aminotransferase level, alanine aminotransferase level, HOMA-IR value, grade of fatty accumulation, total hepatic iron score, and 8-OH-deoxy-2’-guanosine (8-OHdG)-positive cell count. FOXO1 expression was correlated with 8-OHdG-positive cell count, phosphoenolpyruvate carboxykinase (PEPCK) expression, and HOMA-IR. In HepG2 cells, the gene transcription of FOXO1 and PEPCK was increased by DEM treatment, which was associated with an increase in non-phosphorylated FOXO1 protein in the nuclear fraction. Conclusions: Iron-mediated ROS production enhances gluconeogenesis through the FOXO1-mediated pathway and is an affecting factor to IR in patients with CH-C.
文摘The iron aluminides show anomalous stress peaks at temperatures of the order of 400～600 ℃, irrespective of whether the crystal structure is B2 type or DO 3 type. Such features will be examined on the basis of thermally activated dislocation processes, considering the influence of test parameters such as temperature and strain rate, and material parameters such as crystal composition and orientation. Detailed analyses of deformation modes by slip step studies, transmission electron microscopy examinations of dislocation structures, and texture studies will also be considered. Observations of dislocation structures are clearly of great interest for suggesting the possible models of deformation, but suffer from two major weaknesses: the post mortem structures in samples deformed at high temperature may not be the same as those producing plasticity; almost all possible hypotheses for strengthening can find support from such observations, since almost all imaginable dislocation configurations can be found with sufficient diligence by the researcher. Strengthening at intermediate temperatures in DO 3 and B2 ordered iron aluminides will be analysed here, making combined use of observations of deformation structures and examinations of the influence of varying the deformation parameters.
基金Supported by Grants from the Universidade Federal do Pampa,Universidade Federal do Rio Grande do Sul,Universidade Federal de Santa Maria,Fundao de Amparo a Pesquisa do Estado do Rio Grande do Sul(FAPERGS)-FAPERGS/PRONEX,and FAPERGS/PRONEM,Coordenao de Aperfeioamento de Pessoal de Nível Superior,Conselho Nacional de Desenvolvimento Científico e Tecnológico,Financiadora de Estudos e Projetos
文摘AIM: To determine the plasmatic iron content and evaluate the oxidative stress(OS) markers in subjects receiving blood therapy.METHODS: Thirty-nine individuals with unspecified anemia receiving blood transfusions and 15 healthy subjects were included in the study. Anemic subjects were divided into three subgrou P:(1) those that received up to five blood transfusions(n = 14);(2) those that received from five to ten transfusions(n = 11); and(3) those that received more than ten transfusions(n = 14). Blood samples were collected by venous arm puncture and stored in tubes containing heparin. The plasma and cells were separated by centrifugation and subsequently used for analyses. Statistical analyses were performed using Kruskal-Wallis analysis of variance followed by Dunn's multiple comparison tests when appropriate.RESULTS: The eletrophoretic hemoglobin profiles of the subjects included in this study indicated that no patients presented with hemoglobinopathy. Labile plasmatic iron, ferritin, protein carbonyl, thiobarbituric acidreactive substances(TBARS) and dichlorofluorescein diacetate oxidation were significantly higher(P < 0.05), whereas total thiol levels were significantly lower(P < 0.05) in transfused subjects compared to controls. Additionally, the activity of catalase, superoxide dismutase and glutathione peroxidase were significantly lower in the transfused subjects(P < 0.05). Antioxidant enzyme activities and total thiol levels were positively correlated(P < 0.05), and negatively correlated with the levels of protein carbonyl and TBARS(P < 0.05). In contrast, protein carbonyl and TBARS were positively correlated(P < 0.05). Altogether, these data confirm the involvement of OS in patients following therapy with repeated blood transfusions.CONCLUSION: Our data reveal that changes in OS markers are correlated with levels of labile plasmatic iron and ferritin and the number of transfusions.
文摘With the increasing demand for lightweight and lower fuel consumption and safety of automobile industry, lightweight materials of high strength steel (HSS) are more and more widely used. The hot stamping technology, which is determined by the inherent mechanical properties of high strength steel, makes molds prone to wear failure in the harsh service environments. In this paper, a finite element model is proposed for analyzing the value and distributions law of friction shear stress of contact surface of the pin disk. Through the simulation process of sliding wear, two kinds of different cladding materials of the pin specimens including H13 and Fe65, were experimented under three different loads by using the software ABAQUS. And then the pin-on- disk wear test at elevated temperature was conducted to verify the effectiveness of the simula-tion results. The results showed that the friction shear stress of pin with iron-based cladding and H13 steel was different under different loads, but the distribution was basically the same;the normal friction shear stress increased gradually along the direction of the pin movement, and the tangential shear stress increased gradually from the center of the pin to the outside of the circle;the value of the friction shear stress of the normal joints on the contact surface was periodically fluctuating in the whole dynamic analysis step, while it was basically stable in the tangential direction.
