首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 615 毫秒
1.
Russian Journal of Developmental Biology - Agnathans, the most ancient of the extant vertebrates, evoke steadily increasing interest as the object of research on the basic processes of vertebrate...  相似文献   

2.
Pancreatic beta cells secrete insulin in response to elevated plasma glucose levels in a Ca(2+)-dependent fashion. Released insulin may act on the beta cell itself to promote further insulin synthesis and release. Recent studies by Johnson and Misler,1 Masgrau et al.2 and Mitchell et al.3 provide strong evidence (1) for the existence of intracellular Ca(2+) stores sensitive to NAADP, a potent Ca(2+)-mobilizing messenger, and (2) that these Ca(2+) stores are involved in both glucose- and insulin-mediated signal transduction. NAADP may therefore play an important role in controlling secretion of insulin from pancreatic beta cells.  相似文献   

3.

Purpose

Based on the 2005–2014 developments in the Latin American and the Caribbean region (LAC), this paper aims to understand the conditions’ levels for mainstreaming life cycle assessment/life cycle management (LCA/LCM) and map key next actions.

Methods

Along the paper, four mainstreaming conditions are analyzed: expansion of LCM/LCA training activities, availability of LCA studies, national LCA database operating, and existence and activity of national life cycle network(s). Assuming that countries with better conditions are in a better position to develop national LCA based regulations, policies are also researched to complement this study.

Results and discussion

With nine life cycle (LC) networks in 2014, the LAC region has positively developed its networking capacities since 2005 but not the databases area (only one LCA database, Mexicaniuh, is fully operational). It was found that countries with no networks, lack all LCA trainings, studies, and databases.Local capacities are limited which in best case, Chile, does not exceed 18 practitioners per 10 million inhabitants. Based on the total score on mainstreaming conditions, Mexico and Brazil are the most advanced countries, but their markets for LCA professionals are still small (Valdivia et al. 2015), which suggests that tailored made strategies are needed for stronger uptake of LCA by industrial sectors.Argentina, Peru, Chile, and Colombia are in the second tier but still lack a critical mass of business cases and the political will to improve their mainstreaming conditions.

Conclusions

LCA development in the LAC region since 2005 is overall positive but still insufficient to serve the growth of prosperous LCA markets. Well-functioning LC networks are essential to leapfrog LCA. In 2014, about 27 % of LAC countries counted on a LC network. A common language in the region (except for Portuguese in Brazil) has been instrumental for expanding LCA through regional cooperation. LCA-based policies are boosted when local capacities and databases are available following the cases of Mexico, Chile, and Brazil. More data and research are needed to understand the women role in advancing LCA and the causalities and motivations of LAC companies to decide for LCA implementation. The application of the methodology was possible thanks to good quality data available and delivered key findings to develop national road maps for advancing LCA. No indicator used is specific for the LAC region and similar exercises are encouraged in other regions such as Africa and Asia.
  相似文献   

4.
Dengue outbreaks were first reported in East Africa in the late 1970s to early 1980s including the 1982 outbreak on the Kenyan coast. In 2011, dengue outbreaks occurred in Mandera in northern Kenya and subsequently in Mombasa city along the Kenyan coast in 2013–2014. Following laboratory confirmation of dengue fever cases, an entomologic investigation was conducted to establish the mosquito species, and densities, causing the outbreak. Affected parts of the city were identified with the help of public health officials. Adult Ae. aegypti mosquitoes were collected using various tools, processed and screened for dengue virus (DENV) by cell culture and RT-PCR. All containers in every accessible house and compound within affected suburbs were inspected for immatures. A total of 2,065 Ae. aegypti adults were collected and 192 houses and 1,676 containers inspected. An overall house index of 22%, container index, 31.0% (indoor = 19; outdoor = 43) and Breteau index, 270.1, were observed, suggesting that the risk of dengue transmission was high. Overall, jerry cans were the most productive containers (18%), followed by drums (17%), buckets (16%), tires (14%) and tanks (10%). However, each site had specific most-productive container-types such as tanks (17%) in Kizingo; Drums in Nyali (30%) and Changamwe (33%), plastic basins (35%) in Nyali-B and plastic buckets (81%) in Ganjoni. We recommend that for effective control of the dengue vector in Mombasa city, all container types would be targeted. Measures would include proper covering of water storage containers and eliminating discarded containers outdoors through a public participatory environmental clean-up exercise. Providing reliable piped water to all households would minimize the need for water storage and reduce aquatic habitats. Isolation of DENV from male Ae. aegypti mosquitoes is a first observation in Kenya and provides further evidence that transovarial transmission may have a role in DENV circulation and/or maintenance in the environment.  相似文献   

5.
Previous studies showed that adverse effect of ionizing radiation on the cardiovascular system is beside other factors mostly mediated by reactive oxygen and nitrogen species, which deplete antioxidant stores. One of the structures highly sensitive to radicals is the Na,K-ATPase the main system responsible for extrusion of superfluous Na+ out of the cell which utilizes the energy derived from ATP. The aim of present study was the investigation of functional properties of cardiac Na,K-ATPase in 20-week-old male rats 6 weeks after γ-irradiation by a dose 25 Gy (IR). Irradiation induced decrease of systolic blood pressure from 133 in controls to 85 mmHg in IR group together with hypertrophy of right ventricle (RV) and hypotrophy of left ventricle (LV). When activating the cardiac Na,K-ATPase with substrate, its activity was lower in IR in the whole concentration range of ATP. Evaluation of kinetic parameters revealed a decrease of the maximum velocity (V max) by 40 % with no changes in the value of Michaelis–Menten constant (K m). During activation with Na+, we observed a decrease of the enzyme activity in hearts from IR at all tested Na+ concentrations. The value of V max decreased by 38 %, and the concentration of Na+ that gives half maximal reaction velocity (K Na) increased by 62 %. This impairment in the affinity of the Na+-binding site together with decreased number of active Na,K-ATPase molecules, as indicated by lowered V max values, are probably responsible for the deteriorated efflux of the excessive Na+ from the intracellular space in hearts of irradiated rats.  相似文献   

6.
7.
BackgroundCervical cancer is the fourth leading oncological cause of death in women. Variable trends in cervical cancer mortality have been observed across Europe, despite the widespread adoption of screening programs. This variability has previously been attributed to heterogeneity in the quality of screening programs.MethodsAge-standardized cervical cancer death rates for European countries between 1985 and 2014 were analyzed using Joinpoint regression. Countries were dichotomized based on year of implementation and population invitational coverage of national population-based cervical cancer screening programs. National cervical cancer mortality trends during the study period were compared based on this classification.ResultsDecreasing trends in mortality were observed in all European countries with the specific exceptions of Bulgaria, Greece and Latvia. The highest rates of cervical cancer mortality throughout the study period were in Romania (16.0-14.9/100,000) and the lowest rates in Italy (1.4-1.2/100,000). The greatest percentage decline in mortality was observed in the United Kingdom and the greatest absolute reduction in mortality was seen in Hungary. European countries which implemented a national population-based cervical cancer screening program prior to 2009 demonstrated greater improvements in cervical cancer mortality outcomes compared to those that did not (p = 0.016).ConclusionCervical cancer mortality is improving in most European countries; however, substantial variation remains. Trends in mortality were associated with the time of implementation of national population-based cervical screening programs.  相似文献   

8.
Fungal endophyte (FE) communities can be shaped by environmental conditions and/or host-plant affinities. Hawaiʻi's landscape-dominant woody genus Metrosideros (Myrtaceae) comprises several vegetatively distinct taxa that are non-randomly distributed across environments, and their FE communities are poorly known. We examined the relative importance of Metrosideros taxon and environment (elevation) on FE communities on Oʻahu. ITS1 rDNA barcoding and sequencing of 113 trees detected a richness of 1,637 FEs representing 5 phyla, 223 genera, and 200 species. Variation in FE diversity was significantly explained by host taxon and site with considerable overlap in FE communities among taxa. FE communities did not vary between pubescent and glabrous taxa or across elevations, possibly due to the relatively narrow range of environmental conditions represented on Oʻahu relative to taller islands. A significant pattern of isolation by distance in FE composition was detected both among and within sites, consistent with restricted dispersal of FEs across the island.  相似文献   

9.
Mitton JB  Duran KL 《Molecular ecology》2004,13(5):1259-1264
Three previous reports of microgeographical variation of glycerate dehydrogenase (Gly) frequencies in piñon, Pinus edulis, established the hypothesis that Gly frequencies contribute to adaptation to heterogeneous environments, specifically to variation in soil moisture. In each of these studies, the frequency of the Gly‐3 allele or of Gly‐33 homozygotes was higher on dry sites than on nearby moist sites. Here we attempt to extend these observations by testing the hypothesis that Gly frequencies respond to soil moisture variation on a range‐wide scale. Gly frequencies were surveyed in 11 natural populations, and the frequency of the Gly‐3 allele varied from 0.27 to 0.65 among the sample sites. Elevation varied from 1650 to 3100 m, and summer precipitation, defined as precipitation from April to August, varied from 13.7 to 26.4 cm. The soil types at the collection sites were schist, quaternary volcanic or a mixture of shale and sandstone. Logistic regression revealed that Gly frequencies did not respond to either elevation or soil type, but were related to summer precipitation (P < 0.01). The correlation between summer precipitation and the frequency of the Gly‐3 allele was r = ?0.92 (P < 0.001). Thus, the patterns of differentiation on microgeographical scales are consistent with greater differentiation on a range‐wide scale.  相似文献   

10.
The Shule River Basin is an ecologically fragile area in arid zone. To understand the state of land eco-security, the Environment-Economic-Society model was applied to build a land eco-security evaluation index system in the Shule River Basin. An entropy-weighted and matter-element model was built for eco-security evaluation from 2005 to 2014. Principal component analysis was used to quantitatively study the limiting factors of land ecological security. The result showed: the direction of development of the state of land eco-security in the Shule River Basin from 2005 to 2014 was characterized by “unsafe (No4) → safe (No1),” and presented an upward trend. The land eco-security status during 2005–2007 was in the “Unsafe” state and the state changed to “Critical Safe” in 2008–2009, “Safer” in 2010–2011, but “Safe” in 2012–2014. The key factors that affected land eco-security in the Shule River Basin were Per Capita Arable Land, Forest Cover Rate, Per Capita Water Resources, Water Production Modulus, the Tertiary Industry Output Value, and GDP Ratio and Water Consumption. Among them, Forest Cover Rate and Water Production Modulus had the greatest impact, with principal component loads of up to 0.973 and 0.968, respectively. The result of this study is expected to serve as reference and support for the conservation and management of Shule River Basin to ensure sustainable development.  相似文献   

11.
Abstract

Teachers need to be aware of biology misconceptions in their classrooms and how to address them. In response, researchers and science educators have suggested and examined effective practices to prevent and ameliorate misconceptions. An extensive review of the literature gives researchers and educators insights into trends, practices, and gaps in the misconceptions research and helps decide which issues to address and why. The current study shares how researchers in Turkey conduct a content analysis of published misconception research in Turkey by using a form. The analysis resulted in a meta-synthesis (thematic content analysis) that inventoried and compared the purposes, research methods, data collection instruments, and findings of the selected publications. Biology educators in other regions of the world can inform their practice by using this instrument and research methods to learn about trends and patterns in misconception research. Researchers will gain insights into effective methods that have been used to examine misconceptions and will be able to identify biology misconceptions that have been under-investigated and need further analysis.  相似文献   

12.
Effects of Schisandrin B (Sch B) and -tocopherol (-TOC) on ferric chloride (Fe3+) induced oxidation of erythrocyte membrane lipids in vitro and carbon tetrachloride (CCl4) induced lipid peroxidation in vivo were examined. While -TOC could produce prooxidant and antioxidant effect on Fe3+-induced lipid peroxidation, Sch B only inhibited the peroxidation reaction. Pretreatment with -TOC (3 mmol/kg/day × 3) did not protect against CCl4-induced lipid peroxidation and hepatocellular damage in mice, whereas Sch B pretreatment (0.3 mmol/3.0 mmol/kg/day × 3) produced a dose-dependent protective effect on the CCl4-induced hepatotoxicity. The ensemble of results suggests that the ability of Sch B to inhibit lipid peroxidation, while in the absence of pro-oxidant activity, may at least in part contribute to its hepatoprotective action.Abbreviations ALT alanine aminotransferase - CCl4 carbon tetrachloride - Fe3+ ferric chloride - MDA malondialdehyde - Sch B Schisandrin B - TBA 2-thiobarbituric acid - TBARS thiobarbituric acid reactive substances - -TOC dl--tocopherol  相似文献   

13.
Summary Data on karyotype and maternal age of 1954 cases of Down's syndrome were analyzed to see if the rate of chromosome mutations leading to this abnormality has been enhanced during the last 20 years. Comparison of the data for patients born in 1947–1960 with those in 1961–1975 revealed little change with time in the proportions of cases due to different karyotypes, the overwhelming majority being of 21 trisomy type in both periods. However, there has been a remarkable decline in the mean maternal age from 33.1 years to 29.7 years as well as in the variance from 50.5 to 29.4. While the rate of decline in the variance was almost the same as that for all births occurring in the same periods, the decline in the mean maternal age was much greater for the patients than for all births, suggesting that the rate of nondisjunction might have increased in younger rather than in older mothers. However, when the risk of brearing a child with Down's syndrome for mothers aged 40–44 is taken as unity, no evidence was found for an increase with time in the relative risk for younger mothers. Moreover, results of surveys made in 1960 and thereafter in different parts of Japan indicate that the crude incidence rate of Down's syndrome at birth has been around 0.10%, giving no indication of an upward trend. These findings are discussed with reference to the serious environmental pollution, including possible genetic hazards, with which Japan has been faced since the 1960s.  相似文献   

14.
15.

Swine coronaviruses affecting pigs have been studied sporadically in wildlife. In Argentina, epidemiological surveillance of TGEV/PRCV is conducted only in domestic pigs. The aim was to assess the prevalence of TGEV/PRCV in wild Suina. Antibodies against these diseases in wild boar and captive collared peccary were surveyed by ELISA. Antibodies against TGEV were found in three collared peccaries (n?=?87). No TGEV/PRCV antibodies were detected in wild boar (n?=?160). Preventive measures should be conducted in contact nodes where the transmission of agents may increase. Epidemiological surveillance in wildlife populations and in captive animals before their reintroduction should be attempted.

  相似文献   

16.
17.
OBJECTIVE--To assess patient, doctor, practice, and process of care variables for their effect on glycaemic control in diabetes mellitus, and to quantify their relative effects. DESIGN--Search of general practice medical records, patient questionnaires and examination, doctor questionnaire, videotaping and analysis of consultations, and practice questionnaire. SETTING--12 practices with 32 participating general practitioners in Nottinghamshire. SUBJECTS--318 patients randomly selected from those with diabetes in each practice, 10 for each participating doctor. MAIN OUTCOME MEASURE--Glycaemic control as measured by random glycated haemoglobin A1c estimation (random haemoglobin A1 measurement). RESULTS--Glycaemic control was significantly related to the disease process as measured by years since diagnosis, treatment group, and number of diabetes related clinical events. Females had significantly worse control than males. Other patient factors, such as age, social class, lifestyle, attitudes, satisfaction, and knowledge, had no association with glycaemic control. Of all the doctor factors examined, only doctors who professed a special interest in diabetes achieved significantly better glycaemic control. Bigger and better equipped practices and those with a diabetic miniclinic had patients with significantly better glycaemic control, as did those with access to dietetic advice. Patients attending hospital clinics had worse glycaemic control, but this seemed to be attributable to the case mix and practice characteristics. Shared care did not contribute to the multiple linear regression model. CONCLUSION--Glycaemic control among diabetic patients in the community is related to such factors as treatment group, sex, and years since diagnosis; it is also related to the organisation and process of care. The findings support concentrating diabetic care on partners with special interests in diabetes in well equipped practices with adequate dietetic support.  相似文献   

18.
A multitude of plants have been used extensively for the treatment of cancers throughout the world. The protein, α, β momorcharin has been extracted from the plant Momordica charantia (MC), and it possesses anti-cancer and anti-HIV properties similar to the crude water and methanol soluble extract of the plant. This study investigated the anti-cancer effects and the cellular mechanisms of action of α, β momocharin (200–800 μM) on 1321N1, Gos-3, U87-MG, Sk Mel, Corl-23 and Weri Rb-1 cancer cell lines compared to normal healthy L6 muscle cell line measuring cell viability using MTT assay kit, Caspase-3 and 9 activities, cytochrome c release and intracellular free calcium concentrations [Ca2+]i. The results show that α, β momorcharin can evoke significant dose-dependent (P < 0.05; Student’s t test) decreases in the viability (increases in cell death) of 1321N1, Gos-3, U87-MG, Sk Mel, Corl-23 and Weri Rb-1 cancer cell lines compared to healthy L6 muscle cell line and untreated glioma cells. α, β momorcharin (800 μM) also evoked significant (P < 0.05) increases in caspase-3 and 9 activities and cytochrome c release. Similarly, α, β momorcharin elicited significant (P < 0.05) time-dependent elevation in [Ca2+]i in all five glioma cell lines compared to untreated cells. Together, the results have demonstrated that α, β momorcharin can exert its anti-cancer effect on different cancer cell lines by intracellular processes involving an insult to the mitochondria resulting in cellular calcium over loading, apoptosis, cytochrome release and subsequently, cell death.  相似文献   

19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号