Low fertility and population aging are important factors affecting economic and social development.From 2000 to 2020,the development of low fertility in ethnic minority areas shows three trends of accelerated declinin...Low fertility and population aging are important factors affecting economic and social development.From 2000 to 2020,the development of low fertility in ethnic minority areas shows three trends of accelerated declining,slow declining and first falling and then rising,which are the results of the balance between the inhibiting effect of controlling birth policy and the rapidly rising birth cost,and the promoting effect of encouraging birth policy on the fertility desire of social members.The development of aging in ethnic minority areas shows two trends of acceleration and deceleration,which are the results of the balance between the promoting effect of controlling birth policy,the outflow of young and middle-aged labor force and the rise of life expectancy,and the inhibiting effect of the encouraging birth policy,the restraint of talent return and talent introduction.Combined with the development degree of low fertility and aging,we can accurately classify and implement policies for different ethnic minority areas.The areas with serious low fertility and population aging problems need economic policies to change the population age structure as soon as possible.The areas with slight low fertility and population aging problems should carry out ideological policies in priority to maintain the benign structure of population age.展开更多
Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of ...Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of strain.±0.5 % to±1.5 %,the three processes of cyclic hardening,cyclic saturation and cyclic softening were observed.In the same amplitude of strain,the peak stress of the samples pre-treated by DSA is higher than that of solid-solu- tion and cold working pre-treatment,but no remarkable differences of the fatigue lives of them were found.TEM observation shows that the uniform and stable dislocation networks with high density form after DSA pre-treatment,which increases the cyclic peak stress.The cyclic softening results from the low dislocation density and elongated cell structure with low energy.展开更多
The effects of heat treatment on the microstructure and mechanical properties of two alloys, namely Al-12.2%Zn-2.48%Cu-2.0%Mg-0.15%Zr-0.166%Ag(alloy 1), and Al-9.99%Zn-1.72%Cu-2.5%Mg- 0.13%Zr (alloy 2) were invest...The effects of heat treatment on the microstructure and mechanical properties of two alloys, namely Al-12.2%Zn-2.48%Cu-2.0%Mg-0.15%Zr-0.166%Ag(alloy 1), and Al-9.99%Zn-1.72%Cu-2.5%Mg- 0.13%Zr (alloy 2) were investigated. The results show that low temperature aging after promotive solution treatment can increase elongation without the loss of strength for the studied alloys. The optimum aging treatment (T6) for alloy 1 and alloy 2 is 100℃/80h and 100℃/48h, respectively. Compared with other heat treatment alloys, alloy 1 and alloy 2 show super-high tensile strength up to 753MPa and 788MPa, remaining 9.3% and 9.7% elongation under T6 condition, respectively. During aging, trace addition of Ag enhances the formations of GP zone and metastable phase, and stabilizes GP zone and metastable phase to a higher temperature. Trace addition of Ag prolongs the aging time of reaching the peak strength and delays over-aging condition of the alloy. However, trace addition of Ag promotes the formation of coarse constituent in the alloy and consumes hardening alloying elements of Zn and Mg. Moreover, the addition of the transition element Zr in 7000 series super-high alloy forms incoherent Al3Zr dispersoid which can serve as nucleation sites for nonuniform precipitation of η phase during aging process. The higher the aging temperature, the greater the tendency for nonuniform precipitation of η phase.展开更多
Introduction: Low birth weight (LBW) is defined by the World Health Organization (WHO) as a birth weight strictly below 2500 g, whatever the term of pregnancy. It constitutes a major public health problem, both in dev...Introduction: Low birth weight (LBW) is defined by the World Health Organization (WHO) as a birth weight strictly below 2500 g, whatever the term of pregnancy. It constitutes a major public health problem, both in developed and developing countries, due to its magnitude and its strong association with infant morbidity and mortality. Main objective was to study the factors associated with the occurrence of small-for-gestational-age newborns in Douala. Methodology: We carried out a cross-sectional analytical study with prospective data collection using a technical pretested sheet in the maternity wards of the Douala General Hospital, the Laquintinie Hospital, and the District hospitals of Deido, Nylon and Bonassama over a period of 4 months (January to April 2020). We were interested in any newborn, born alive, vaginally or by cesarean section, of low weight, seen in the first 24 hours from a full-term single-fetal pregnancy whose mother had given her consent. Our sampling was consecutive and non-exhaustive. We excluded newborns whose term was unclear and those with congenital malformations or signs of embryo-foetopathy. Data collection was done using survey sheets. Statistical analyzes were carried out with CS Pro 7.3 and SPSS version 25.0 software. The Student, Chi-square and Fischer tests were used to compare the means of the variables, the percentages with a significance threshold P value Results: During the study period, 305 full-term newborns were included, divided into 172 boys and 133 girls. The percentage of small-for-gestational-age newborns was 9.8%;after multivariate analysis by logistic regression to eliminate confounding factors, we found maternal factors associated with small for gestational age newborns;maternal age less than 20 years, primiparity, gestational age (37 - 38), a delay in prenatal visits greater than 14 weeks, anemia in pregnancy, positive toxoplasmosis serology in pregnancy, a body mass index of Conclusion: Our study revealed the potential determinants of low birth weight at term in the Cameroonian urban context and specifically in Douala.展开更多
The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatt...The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatter diffraction analysis of misorientation angle distribution, cumulative misorientation and geometrically necessary dislocation (GND) density. Experimental results indicate that coarse spindle-shaped grains with the dimension of 200 μm- 80 μm separate into fine equiaxed grains of 20μm in size as a result of newborn low-angle grain boundaries formed during the aging process. More specifically, the dislocation arrays, which are rearranged and formed due to scattered dislocations during earlier quenching, transform into low-angle grain boundaries with aging time. The relative frequency of 3°-5° low-angle grain boundaries increases to over 30%. The GND density, which describes low-angle grain boundaries with the misorientation angle under 3°, tends to decrease during initial aging. The inhomogeneous distribution of GNDs is affected by grain orientation. A decrease in GND density mainly occurs from 1.83 × 10^13 to 4.40 × 10^11 m^-2 in grains with 〈111〉 fiber texture. This is consistent with a decrease of unit cumulative misorientation. Precipitation on grain boundaries and the formation of a precipitation free zone (PFZ) are facilitated due to the eroding activity of the Graft etchant. Consequently, low-angle grain boundaries could be readily viewed by optical microscopy due to an increase in their electric potential difference.展开更多
In this editorial we comment on the article by Fukushi K et al published in the recent issue of the World Journal of Gastroenterology 2018; 24(34): 3908-3918. We focus specifically on the mechanisms of the anti-thromb...In this editorial we comment on the article by Fukushi K et al published in the recent issue of the World Journal of Gastroenterology 2018; 24(34): 3908-3918. We focus specifically on the mechanisms of the anti-thrombotic action of aspirin, gastric mucosal injury and aging-related increased susceptibility of gastric mucosa to injury. Aspirin is widely used not only for the management of acute and chronic pain and arthritis, but also importantly for the primary and secondary prevention of cardiovascular events such as myocardial infarcts and strokes. Clinical trials have consistently shown that antiplatelet therapy with long term, low dose aspirin(LDA)-75 to 325 mg daily, dramatically reduces the risk of non-fatal myocardial infarcts, stroke and mortality in patients with established arterial diseases. However, such treatment considerably increases the risk of gastrointestinal(GI) ulcerations and serious bleeding by > 2-4 fold, especially in aging individuals. This risk is further increased in patients using LDA together with other antiplatelet agents, other nonsteroidal anti-inflammatory agents(NSAIDs) and/or alcohol, or in patients with Helicobacter pylori(H. pylori) infection. Previous studies by our group and others have demonstrated prominent structural and functional abnormalities in gastric mucosa of aging individuals(which we refer to as aging gastric mucosa or "aging gastropathy") compared to the gastric mucosa of younger individuals. Aging gastric mucosa has impaired mucosal defense, increased susceptibility to injury by a variety of noxious agents such as aspirin, other NSAIDs and ethanol, and delayed and impaired healing of injury. The mechanism underlying these abnormalities of aging gastric mucosa include reduced mucosal blood flowcausing hypoxia, upregulation of PTEN, activation of proapoptotic caspase-3 and caspase-9, and reduced survivin(anti-apoptosis protein), importin-α(nuclear transport protein), vascular endothelial growth factor, and nerve growth factor. The decision regarding initiation of a long-term LDA therapy should be made after a careful consideration of both cardiovascular and GI risk factors. The latter include a previous history of GI bleeding and/or ulcers, age ≥ 70, male gender, concurrent use of other NSAIDs, alcohol consumption and H. pylori infection. Furthermore, the incidence of GI ulcers and bleeding can be reduced in patients on long term LDA treatment by several measures. Clinicians treating such patients should test for and eradicate H. pylori, instruct patients to avoid alcohol and non-aspirin NSAIDs, including cyclooxygenase-2-selective NSAIDs, and prescribe proton pump inhibitors in patients on LDA therapy. In the future, clinicians may be able to prescribe one of several potential new drugs, which include aspirin associated with phosphatidylcholine(PL2200), which retains all property of aspirin but reduces by approximately 50% LDA-induced GI ulcerations.展开更多
Aim: To examine the effects on rat aging of caloric restriction (CR1) and undernutrition (CR2) on the body and on testicular weights, on two enzymatic antioxidants (superoxide dismutase and catalase), on lipid ...Aim: To examine the effects on rat aging of caloric restriction (CR1) and undernutrition (CR2) on the body and on testicular weights, on two enzymatic antioxidants (superoxide dismutase and catalase), on lipid peroxidation and on the expression of testicular aromatase and estrogen receptors (ER). Methods: CR was initiated in 1-month-old rats and carried on until the age of 18 months. Results: In control and CR2 rats an age-related decrease of the aromatase and of ER (α and β) gene expression was observed; in parallel a diminution of testicular weights, and of the total number and motility of epididymal spermatozo was recorded. In addition, aging in control and CR2 rats was accompartied by a significant decrease in testicular superoxide dismutase, catalase activities, and an increase in lipid peroxidation level (thiobarbituric acid reactive substance), associated with alterations of spermatogenesis. Conversely, caloric restriction-treatment exerted a protective effect and all the parameters were less affected by aging. Conclusion: These results indicate that during aging, a low caloric diet (not undernutrition) is beneficial for spermatogenesis and likely improves the protection of the cells via an increase of the cellular antioxidant defense system in which aromatase/ ER could play a role. (Asian J Andro12008 Mar; 10: 177-187)展开更多
Objectives: Current study sought to determine an association between Low Birth Weight (LBW) and early neonatal mortality at a resource limited country’s referral hospital and to determine relationship between materna...Objectives: Current study sought to determine an association between Low Birth Weight (LBW) and early neonatal mortality at a resource limited country’s referral hospital and to determine relationship between maternal age and birth outcomes. Method: A retrospective study analyzing data on births in the Volta Regional Hospital, Ghana from the period of November 2011 to June 2016. A total of 8279 births were analyzed. Results: Results suggest that teenage mothers (8.60%) are more likely to give birth to pre-term babies than the elderly (6.60%) and the adult mothers (4.61%). LBW is highest among the teenage mothers (12.69%) followed by the elderly mothers (7.87%) and then the least among the adult mothers (6.48%). Extremely Low Birth Weight (ELBW) and Macrosomia births were more observed among the elderly mothers (0.90%;2.17%) than the teenage (0.28%;0.14%) and adult mothers (0.34%;1.61%) respectively. Data suggest that 100% of the ELBW were pre-term birth, 88.28% Very Low Birth Weight (VLBW), 34.56% LBW and only 1.06% of the pre-term birth were with Normal Birth Weight (NBW). Death rate ranges from 50% for ELBW, 33.59% for VLBW, 8.22% for LBW, 5.43% for Macrosomia and 1.5% for NBW. However, death rate distribution among the various age groups was statistically not significant (P 0.106). Conclusions: Our study suggests that early neonatal death, especially deaths among ELBW and VLBW is still high at the VRH of Ghana and therefore there is the need for further studies into interventions to reduce death among neonates born with VLBW and ELBW.展开更多
Age-related Ecto-Nicotinamide Adenine Dinucleotide Oxidase Disulfide Thiol Exchangers 3 (ENOX3) or age-related NADH oxidases (arNOX) are expressed at the cell surface as five members of the TM-9 superfamily, initially...Age-related Ecto-Nicotinamide Adenine Dinucleotide Oxidase Disulfide Thiol Exchangers 3 (ENOX3) or age-related NADH oxidases (arNOX) are expressed at the cell surface as five members of the TM-9 superfamily, initially membrane anchored, all functionally similar, with the N-termini exposed at the cell’s exterior. ECTO-NOXes are cell surface proteins with both time-keeping CoQH2 [NAD(P)H] oxidase and protein disulfidethiol interchange activities. They are designated as ECTO-NOX proteins because of their localization on the outer surface of the plasma membrane and to distinguish them from the phox-NOXes of host defense. A ca. 30 kDa N-terminal fragment is cleaved and accumulates in body fluids (serum, saliva, urine, perspiration). arNOXes appear around age 30 and increase steadily thereafter. Reduced quinones, i.e., reduced coenzyme Q, of the plasma membrane are natural substrates. NAD(P)H is oxidized as an artificial substrate. In one phase of the arNOX cycle electrons are transferred to oxygen to generate superoxide. Substrates for the shed forms of arNOX appear to be proteins of body fluids. Circulating lipoproteins and skin matrix proteins emerge as potentially important health-related targets. Through oxidation of collagen, elastin and other proteins of the skin matrix, arNOXes are major contributors to skin aging through tyrosine and thiol oxidation and subsequent cross linking. The main destructive action of arNOX, however, may be to directly oxidize circulating lipoproteins. arNOX in the blood is structured as an integral component of the LDL particle through site-specific binding. As such, arNOXes are implicated as major risk factors for cardiovascular disease due to specific oxidation of LDLs. The superoxide produced and its conversion to hydrogen peroxide would be one part of the potentially destructive properties by contribution to lipid oxidation. Inhibition of arNOX proteins provides a rational basis for anti-aging interventions and their elimination as a major risk factor of atherogenesis.展开更多
A creep technique was applied on a Gleeble-1500 thermal simulator for monitoring the aging precipitation in ultra-low carbon steels containing various coppers. The aging hardening curve was obtained by the hardness te...A creep technique was applied on a Gleeble-1500 thermal simulator for monitoring the aging precipitation in ultra-low carbon steels containing various coppers. The aging hardening curve was obtained by the hardness testing. With the aid of an optical microscope and TEM, the microstructure and the aging precipitates were detected. The results indicate that when the precipitation occurs during the creep a plateau will appear on the creep curve; the left-hand and right-hand endings of the plateau correspond to the precipitation start (Ps) and finish (Pf) times, respectively. The Pf obtained from the creep curve coincides with the peak hardness time (tp) at the aging hardening curve. A precipitation-time-temperature (PTT) diagram of the steel can be obtained.展开更多
The 5-parameter Morse potential (5-MP) of the interaction between H atom and Ag surfaces has been constructed. The adsorption and diffusion of H on Ag low-index surfaces are investigated with 5-MP in detail. The cha...The 5-parameter Morse potential (5-MP) of the interaction between H atom and Ag surfaces has been constructed. The adsorption and diffusion of H on Ag low-index surfaces are investigated with 5-MP in detail. The characteristics of critical points are obtained. The theoretical results show that H atom can only adsorb at the three-fold site on Ag(111 ); the quasi-3-fold site and long-bridge site are stable adsorption sites on Ag(110) surface for the H atom, and at low coverage hydrogen predominantly occupies the quasi-3-fold site. This work predicts that the four-fold hollow site is the most stable adsorption state for H atom on Ag(100). The results of this work are approved by the experimental and theoretical results.展开更多
AIM:To compare the efficacy of low-fluence photodynamic therapy(PDT) combinations in the treatment of age-related macular degeneration(AMD).· METHODS:Forty-five previously untreated eyes of 45 patients with exuda...AIM:To compare the efficacy of low-fluence photodynamic therapy(PDT) combinations in the treatment of age-related macular degeneration(AMD).· METHODS:Forty-five previously untreated eyes of 45 patients with exudative AMD whose best-corrected visual acuity(BCVA) was ≥0.3(Snellen) were enrolled.15 patients in Group I underwent low-fluence PDT(25J/cm2-300mW/cm2-83sec) and intravitreal pegaptanib combination,15 patients in Group II underwent PDT(50J/cm2-600mW/cm2-83sec) and intravitreal pegaptanib combination while,15 patients in Group III underwent intravitreal pegaptanib monotherapy.Complete ophthalmologic examinations were performed in pre and post treatment visits,and the results were statistically analised.A clinical activity score(CAS) was calculated by using changes in lesion size,amount of hemorrhage,staining pattern in FA and OCT measurement of intra/subretinal fluid.≤3 logMAR lines of decrease in BCVA and decrease in CAS were considered as successful treatment.· RESULTS:The mean age of 19 female(42.2%) and 26 male(57.8%) patients was(72.82±8.02) years.Mean follow-up was(13.93±5.87) months.Lesion type was occult in 28 eyes(62.2%).Treatment success rates according to BCVA assessments were 86.7%,80%,60% and mean BCVA decrease were 0.3,1.0,2.2 logMAR lines in Group I,II and III,respectively(P >0.05).According to the changes in central macular thickness and CAS,no difference was found among the study groups(P =0.850 and P =0.811,respectively).Patients treated with combination regimens had lower intravitreal injection frequencies(P =0.015).· CONCLUSION:Combination regimen with intravitreal pegaptanib and low-fluence PDT seems to be safe and effective in stabilizing the clinical activity and BCVA in exudative AMD.·展开更多
基金supported by the Youth Project of Beijing Academy of Social Sciences(GrantNo.2022B6949)supported the project of Shanxi Academy of Education Sciences(Grant No.GH-21117)。
文摘Low fertility and population aging are important factors affecting economic and social development.From 2000 to 2020,the development of low fertility in ethnic minority areas shows three trends of accelerated declining,slow declining and first falling and then rising,which are the results of the balance between the inhibiting effect of controlling birth policy and the rapidly rising birth cost,and the promoting effect of encouraging birth policy on the fertility desire of social members.The development of aging in ethnic minority areas shows two trends of acceleration and deceleration,which are the results of the balance between the promoting effect of controlling birth policy,the outflow of young and middle-aged labor force and the rise of life expectancy,and the inhibiting effect of the encouraging birth policy,the restraint of talent return and talent introduction.Combined with the development degree of low fertility and aging,we can accurately classify and implement policies for different ethnic minority areas.The areas with serious low fertility and population aging problems need economic policies to change the population age structure as soon as possible.The areas with slight low fertility and population aging problems should carry out ideological policies in priority to maintain the benign structure of population age.
文摘Studies were made of the symmetric tensile-compressive low cycle fatigue behaviour and the influence of dynamic strain aging(DSA)pre-treatment of 18-8 austenitic stainless steel. Within the testing amplitude range of strain.±0.5 % to±1.5 %,the three processes of cyclic hardening,cyclic saturation and cyclic softening were observed.In the same amplitude of strain,the peak stress of the samples pre-treated by DSA is higher than that of solid-solu- tion and cold working pre-treatment,but no remarkable differences of the fatigue lives of them were found.TEM observation shows that the uniform and stable dislocation networks with high density form after DSA pre-treatment,which increases the cyclic peak stress.The cyclic softening results from the low dislocation density and elongated cell structure with low energy.
基金Project (2001AA332030) supported by the National High Technology Research and Development Programof China
文摘The effects of heat treatment on the microstructure and mechanical properties of two alloys, namely Al-12.2%Zn-2.48%Cu-2.0%Mg-0.15%Zr-0.166%Ag(alloy 1), and Al-9.99%Zn-1.72%Cu-2.5%Mg- 0.13%Zr (alloy 2) were investigated. The results show that low temperature aging after promotive solution treatment can increase elongation without the loss of strength for the studied alloys. The optimum aging treatment (T6) for alloy 1 and alloy 2 is 100℃/80h and 100℃/48h, respectively. Compared with other heat treatment alloys, alloy 1 and alloy 2 show super-high tensile strength up to 753MPa and 788MPa, remaining 9.3% and 9.7% elongation under T6 condition, respectively. During aging, trace addition of Ag enhances the formations of GP zone and metastable phase, and stabilizes GP zone and metastable phase to a higher temperature. Trace addition of Ag prolongs the aging time of reaching the peak strength and delays over-aging condition of the alloy. However, trace addition of Ag promotes the formation of coarse constituent in the alloy and consumes hardening alloying elements of Zn and Mg. Moreover, the addition of the transition element Zr in 7000 series super-high alloy forms incoherent Al3Zr dispersoid which can serve as nucleation sites for nonuniform precipitation of η phase during aging process. The higher the aging temperature, the greater the tendency for nonuniform precipitation of η phase.
文摘Introduction: Low birth weight (LBW) is defined by the World Health Organization (WHO) as a birth weight strictly below 2500 g, whatever the term of pregnancy. It constitutes a major public health problem, both in developed and developing countries, due to its magnitude and its strong association with infant morbidity and mortality. Main objective was to study the factors associated with the occurrence of small-for-gestational-age newborns in Douala. Methodology: We carried out a cross-sectional analytical study with prospective data collection using a technical pretested sheet in the maternity wards of the Douala General Hospital, the Laquintinie Hospital, and the District hospitals of Deido, Nylon and Bonassama over a period of 4 months (January to April 2020). We were interested in any newborn, born alive, vaginally or by cesarean section, of low weight, seen in the first 24 hours from a full-term single-fetal pregnancy whose mother had given her consent. Our sampling was consecutive and non-exhaustive. We excluded newborns whose term was unclear and those with congenital malformations or signs of embryo-foetopathy. Data collection was done using survey sheets. Statistical analyzes were carried out with CS Pro 7.3 and SPSS version 25.0 software. The Student, Chi-square and Fischer tests were used to compare the means of the variables, the percentages with a significance threshold P value Results: During the study period, 305 full-term newborns were included, divided into 172 boys and 133 girls. The percentage of small-for-gestational-age newborns was 9.8%;after multivariate analysis by logistic regression to eliminate confounding factors, we found maternal factors associated with small for gestational age newborns;maternal age less than 20 years, primiparity, gestational age (37 - 38), a delay in prenatal visits greater than 14 weeks, anemia in pregnancy, positive toxoplasmosis serology in pregnancy, a body mass index of Conclusion: Our study revealed the potential determinants of low birth weight at term in the Cameroonian urban context and specifically in Douala.
文摘The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatter diffraction analysis of misorientation angle distribution, cumulative misorientation and geometrically necessary dislocation (GND) density. Experimental results indicate that coarse spindle-shaped grains with the dimension of 200 μm- 80 μm separate into fine equiaxed grains of 20μm in size as a result of newborn low-angle grain boundaries formed during the aging process. More specifically, the dislocation arrays, which are rearranged and formed due to scattered dislocations during earlier quenching, transform into low-angle grain boundaries with aging time. The relative frequency of 3°-5° low-angle grain boundaries increases to over 30%. The GND density, which describes low-angle grain boundaries with the misorientation angle under 3°, tends to decrease during initial aging. The inhomogeneous distribution of GNDs is affected by grain orientation. A decrease in GND density mainly occurs from 1.83 × 10^13 to 4.40 × 10^11 m^-2 in grains with 〈111〉 fiber texture. This is consistent with a decrease of unit cumulative misorientation. Precipitation on grain boundaries and the formation of a precipitation free zone (PFZ) are facilitated due to the eroding activity of the Graft etchant. Consequently, low-angle grain boundaries could be readily viewed by optical microscopy due to an increase in their electric potential difference.
基金Merit Review Award from the United States Department of Veterans Affairs Biomedical Laboratory Research and Development Service,No.I01 BX000626-05A2 to Tarnawski AS
文摘In this editorial we comment on the article by Fukushi K et al published in the recent issue of the World Journal of Gastroenterology 2018; 24(34): 3908-3918. We focus specifically on the mechanisms of the anti-thrombotic action of aspirin, gastric mucosal injury and aging-related increased susceptibility of gastric mucosa to injury. Aspirin is widely used not only for the management of acute and chronic pain and arthritis, but also importantly for the primary and secondary prevention of cardiovascular events such as myocardial infarcts and strokes. Clinical trials have consistently shown that antiplatelet therapy with long term, low dose aspirin(LDA)-75 to 325 mg daily, dramatically reduces the risk of non-fatal myocardial infarcts, stroke and mortality in patients with established arterial diseases. However, such treatment considerably increases the risk of gastrointestinal(GI) ulcerations and serious bleeding by > 2-4 fold, especially in aging individuals. This risk is further increased in patients using LDA together with other antiplatelet agents, other nonsteroidal anti-inflammatory agents(NSAIDs) and/or alcohol, or in patients with Helicobacter pylori(H. pylori) infection. Previous studies by our group and others have demonstrated prominent structural and functional abnormalities in gastric mucosa of aging individuals(which we refer to as aging gastric mucosa or "aging gastropathy") compared to the gastric mucosa of younger individuals. Aging gastric mucosa has impaired mucosal defense, increased susceptibility to injury by a variety of noxious agents such as aspirin, other NSAIDs and ethanol, and delayed and impaired healing of injury. The mechanism underlying these abnormalities of aging gastric mucosa include reduced mucosal blood flowcausing hypoxia, upregulation of PTEN, activation of proapoptotic caspase-3 and caspase-9, and reduced survivin(anti-apoptosis protein), importin-α(nuclear transport protein), vascular endothelial growth factor, and nerve growth factor. The decision regarding initiation of a long-term LDA therapy should be made after a careful consideration of both cardiovascular and GI risk factors. The latter include a previous history of GI bleeding and/or ulcers, age ≥ 70, male gender, concurrent use of other NSAIDs, alcohol consumption and H. pylori infection. Furthermore, the incidence of GI ulcers and bleeding can be reduced in patients on long term LDA treatment by several measures. Clinicians treating such patients should test for and eradicate H. pylori, instruct patients to avoid alcohol and non-aspirin NSAIDs, including cyclooxygenase-2-selective NSAIDs, and prescribe proton pump inhibitors in patients on LDA therapy. In the future, clinicians may be able to prescribe one of several potential new drugs, which include aspirin associated with phosphatidylcholine(PL2200), which retains all property of aspirin but reduces by approximately 50% LDA-induced GI ulcerations.
文摘Aim: To examine the effects on rat aging of caloric restriction (CR1) and undernutrition (CR2) on the body and on testicular weights, on two enzymatic antioxidants (superoxide dismutase and catalase), on lipid peroxidation and on the expression of testicular aromatase and estrogen receptors (ER). Methods: CR was initiated in 1-month-old rats and carried on until the age of 18 months. Results: In control and CR2 rats an age-related decrease of the aromatase and of ER (α and β) gene expression was observed; in parallel a diminution of testicular weights, and of the total number and motility of epididymal spermatozo was recorded. In addition, aging in control and CR2 rats was accompartied by a significant decrease in testicular superoxide dismutase, catalase activities, and an increase in lipid peroxidation level (thiobarbituric acid reactive substance), associated with alterations of spermatogenesis. Conversely, caloric restriction-treatment exerted a protective effect and all the parameters were less affected by aging. Conclusion: These results indicate that during aging, a low caloric diet (not undernutrition) is beneficial for spermatogenesis and likely improves the protection of the cells via an increase of the cellular antioxidant defense system in which aromatase/ ER could play a role. (Asian J Andro12008 Mar; 10: 177-187)
文摘Objectives: Current study sought to determine an association between Low Birth Weight (LBW) and early neonatal mortality at a resource limited country’s referral hospital and to determine relationship between maternal age and birth outcomes. Method: A retrospective study analyzing data on births in the Volta Regional Hospital, Ghana from the period of November 2011 to June 2016. A total of 8279 births were analyzed. Results: Results suggest that teenage mothers (8.60%) are more likely to give birth to pre-term babies than the elderly (6.60%) and the adult mothers (4.61%). LBW is highest among the teenage mothers (12.69%) followed by the elderly mothers (7.87%) and then the least among the adult mothers (6.48%). Extremely Low Birth Weight (ELBW) and Macrosomia births were more observed among the elderly mothers (0.90%;2.17%) than the teenage (0.28%;0.14%) and adult mothers (0.34%;1.61%) respectively. Data suggest that 100% of the ELBW were pre-term birth, 88.28% Very Low Birth Weight (VLBW), 34.56% LBW and only 1.06% of the pre-term birth were with Normal Birth Weight (NBW). Death rate ranges from 50% for ELBW, 33.59% for VLBW, 8.22% for LBW, 5.43% for Macrosomia and 1.5% for NBW. However, death rate distribution among the various age groups was statistically not significant (P 0.106). Conclusions: Our study suggests that early neonatal death, especially deaths among ELBW and VLBW is still high at the VRH of Ghana and therefore there is the need for further studies into interventions to reduce death among neonates born with VLBW and ELBW.
文摘Age-related Ecto-Nicotinamide Adenine Dinucleotide Oxidase Disulfide Thiol Exchangers 3 (ENOX3) or age-related NADH oxidases (arNOX) are expressed at the cell surface as five members of the TM-9 superfamily, initially membrane anchored, all functionally similar, with the N-termini exposed at the cell’s exterior. ECTO-NOXes are cell surface proteins with both time-keeping CoQH2 [NAD(P)H] oxidase and protein disulfidethiol interchange activities. They are designated as ECTO-NOX proteins because of their localization on the outer surface of the plasma membrane and to distinguish them from the phox-NOXes of host defense. A ca. 30 kDa N-terminal fragment is cleaved and accumulates in body fluids (serum, saliva, urine, perspiration). arNOXes appear around age 30 and increase steadily thereafter. Reduced quinones, i.e., reduced coenzyme Q, of the plasma membrane are natural substrates. NAD(P)H is oxidized as an artificial substrate. In one phase of the arNOX cycle electrons are transferred to oxygen to generate superoxide. Substrates for the shed forms of arNOX appear to be proteins of body fluids. Circulating lipoproteins and skin matrix proteins emerge as potentially important health-related targets. Through oxidation of collagen, elastin and other proteins of the skin matrix, arNOXes are major contributors to skin aging through tyrosine and thiol oxidation and subsequent cross linking. The main destructive action of arNOX, however, may be to directly oxidize circulating lipoproteins. arNOX in the blood is structured as an integral component of the LDL particle through site-specific binding. As such, arNOXes are implicated as major risk factors for cardiovascular disease due to specific oxidation of LDLs. The superoxide produced and its conversion to hydrogen peroxide would be one part of the potentially destructive properties by contribution to lipid oxidation. Inhibition of arNOX proteins provides a rational basis for anti-aging interventions and their elimination as a major risk factor of atherogenesis.
基金financially supported by the National Natural Science Foundation of China (No. 50471089)
文摘A creep technique was applied on a Gleeble-1500 thermal simulator for monitoring the aging precipitation in ultra-low carbon steels containing various coppers. The aging hardening curve was obtained by the hardness testing. With the aid of an optical microscope and TEM, the microstructure and the aging precipitates were detected. The results indicate that when the precipitation occurs during the creep a plateau will appear on the creep curve; the left-hand and right-hand endings of the plateau correspond to the precipitation start (Ps) and finish (Pf) times, respectively. The Pf obtained from the creep curve coincides with the peak hardness time (tp) at the aging hardening curve. A precipitation-time-temperature (PTT) diagram of the steel can be obtained.
基金The project was supported by NSF of Shandong Province (Y2002B09)
文摘The 5-parameter Morse potential (5-MP) of the interaction between H atom and Ag surfaces has been constructed. The adsorption and diffusion of H on Ag low-index surfaces are investigated with 5-MP in detail. The characteristics of critical points are obtained. The theoretical results show that H atom can only adsorb at the three-fold site on Ag(111 ); the quasi-3-fold site and long-bridge site are stable adsorption sites on Ag(110) surface for the H atom, and at low coverage hydrogen predominantly occupies the quasi-3-fold site. This work predicts that the four-fold hollow site is the most stable adsorption state for H atom on Ag(100). The results of this work are approved by the experimental and theoretical results.
文摘AIM:To compare the efficacy of low-fluence photodynamic therapy(PDT) combinations in the treatment of age-related macular degeneration(AMD).· METHODS:Forty-five previously untreated eyes of 45 patients with exudative AMD whose best-corrected visual acuity(BCVA) was ≥0.3(Snellen) were enrolled.15 patients in Group I underwent low-fluence PDT(25J/cm2-300mW/cm2-83sec) and intravitreal pegaptanib combination,15 patients in Group II underwent PDT(50J/cm2-600mW/cm2-83sec) and intravitreal pegaptanib combination while,15 patients in Group III underwent intravitreal pegaptanib monotherapy.Complete ophthalmologic examinations were performed in pre and post treatment visits,and the results were statistically analised.A clinical activity score(CAS) was calculated by using changes in lesion size,amount of hemorrhage,staining pattern in FA and OCT measurement of intra/subretinal fluid.≤3 logMAR lines of decrease in BCVA and decrease in CAS were considered as successful treatment.· RESULTS:The mean age of 19 female(42.2%) and 26 male(57.8%) patients was(72.82±8.02) years.Mean follow-up was(13.93±5.87) months.Lesion type was occult in 28 eyes(62.2%).Treatment success rates according to BCVA assessments were 86.7%,80%,60% and mean BCVA decrease were 0.3,1.0,2.2 logMAR lines in Group I,II and III,respectively(P >0.05).According to the changes in central macular thickness and CAS,no difference was found among the study groups(P =0.850 and P =0.811,respectively).Patients treated with combination regimens had lower intravitreal injection frequencies(P =0.015).· CONCLUSION:Combination regimen with intravitreal pegaptanib and low-fluence PDT seems to be safe and effective in stabilizing the clinical activity and BCVA in exudative AMD.·