1,720,955 research outputs found
Investigating the Effect of Polystyrene Nanoplastics on Female Reproductive System
Get PDFAbstract
Introduction
The degradation of plastic waste into smaller micro- and nanoplastic (MNPs) molecules has led to widespread distribution of these particles and accumulation in the environment, making human exposure inevitable. This can result in, or exacerbate, pathological conditions leading to immune dysfunction, neurodegenerative diseases, and infertility. Yet few studies have examined the effects of nanoplastics (NPs) on human health, especially the reproductive system. Reproductive toxicity of plastic particles has been mostly studied in males with most studies investigating microplastics. Therefore, the present study aims to assess the reproductive health consequences of NPs exposure in females by quantifying serum estradiol and progesterone, examining estrous cyclicity, and assessing ovarian reserve (number and quality of follicles) which is a key indicator of female fertility.
Materials & Methods
The present study was carried out in female mice (C57BL/6) exposed orally to water (control) or one of two solutions containing different concentrations of Polystyrene nanoplastics (PS-NPs; 100 µg/l or 1000 µg/l in water. Exposure occurred daily for 29 days, and vaginal lavage samples were collected for the last 15 days of the exposure phase to check for change in estrous cyclicity. Mice were euthanized at the end of the study and their blood samples and reproductive tissues were collected. Ovaries were fixed in 10% formalin, embedded in paraffin wax, serially sectioned at 5 µm thickness, and stained with hematoxylin and eosin (H&E) for microscopy and follicle analysis. ELISA was also performed to quantify the progesterone and estradiol serum levels.
Results
There was a significant increase in the estrous cycle length in the high dose (1000 µg/l) PS-NPs exposure group compared to control (5.53±.25 days vs 4.7±0.23 days, P=0.02). Moreover, there was a significant decrease in serum progesterone levels in the high-dose exposure group compared to control (mean difference=1.64 pg/ml, standard error of difference (SED)=0.64, P=0.03). Additionally, it was shown that PS-NPs exposure significantly reduced antral follicles’ diameter in both the low dose (238.61±19.01 µm vs 167.35±19.01 µm, P=0.03) and high dose exposure groups compared to the control group with the higher dose showing a more pronounced reduction in antral follicle' size (238.61±19.01 µm vs 131.95±19.01 µm, P=0.001).
Conclusion
Oral PS-NPs exposure in female mice appears to induce toxicity by reducing antral follicles size, increasing the estrous cycle length, and decreasing progesterone levels which may result in anovulation and different reproductive issues, such as infertility and polycystic ovary syndrome (PCOS). The effect of PS-NPs on infertility along with NPs’ mechanism of action in female reproductive system should be investigated in future studies.ThesisMaster of Science (MSc)Plastics in the environment break down into smaller particles called micro- and nanoplastics. These plastic particles are pollutants present in the aquatic and terrestrial environments entering every level of the food chain and ultimately reaching humans, yet few studies have examined the effects of nanoplastics on human health. A recent World Health Organization (WHO) report on nanoplastics has stressed the urgent need for toxicological studies to assess potential human health effects. Therefore, this study examined the effect of nanoplastics on the female reproductive system. This study was carried out in female mice exposed orally to a solution containing a vehicle control (water) and two different concentrations of nanoplastics (100 and 1,000 µg/l). Exposure occurred daily for a period of 29 days. At the conclusion of the study the mice were humanly euthanized with their blood and reproductive tissues collected for laboratory analysis. Results showed that nanoplastics exposure resulted in irregular reproductive cycle in mice along with a decrease in antral follicle size and progesterone levels which are indicators of anovulation and can lead to disorders, such as infertility and polycystic ovary syndrome (PCOS) which should be further investigated in future studies
Investigating the Effect of Polystyrene Nanoplastics on Female Reproductive System
Get PDFIntroduction
The degradation of plastic waste into smaller micro- and nanoplastic (MNPs) molecules has led to widespread distribution of these particles and accumulation in the environment, making human exposure inevitable. This can result in, or exacerbate, pathological conditions leading to immune dysfunction, neurodegenerative diseases, and infertility. Yet few studies have examined the effects of nanoplastics (NPs) on human health, especially the reproductive system. Reproductive toxicity of plastic particles has been mostly studied in males with most studies investigating microplastics. Therefore, the present study aims to assess the reproductive health consequences of NPs exposure in females by quantifying serum estradiol and progesterone, examining estrous cyclicity, and assessing ovarian reserve (number and quality of follicles) which is a key indicator of female fertility.
Materials & Methods
The present study was carried out in female mice (C57BL/6) exposed orally to water (control) or one of two solutions containing different concentrations of Polystyrene nanoplastics (PS-NPs; 100 µg/l or 1000 µg/l in water. Exposure occurred daily for 29 days, and vaginal lavage samples were collected for the last 15 days of the exposure phase to check for change in estrous cyclicity. Mice were euthanized at the end of the study and their blood samples and reproductive tissues were collected. Ovaries were fixed in 10% formalin, embedded in paraffin wax, serially sectioned at 5 µm thickness, and stained with hematoxylin and eosin (H&E) for microscopy and follicle analysis. ELISA was also performed to quantify the progesterone and estradiol serum levels.
Results
There was a significant increase in the estrous cycle length in the high dose (1000 µg/l) PS-NPs exposure group compared to control (5.53±.25 days vs 4.7±0.23 days, P=0.02). Moreover, there was a significant decrease in serum progesterone levels in the high-dose exposure group compared to control (mean difference=1.64 pg/ml, standard error of difference (SED)=0.64, P=0.03). Additionally, it was shown that PS-NPs exposure significantly reduced antral follicles’ diameter in both the low dose (238.61±19.01 µm vs 167.35±19.01 µm, P=0.03) and high dose exposure groups compared to the control group with the higher dose showing a more pronounced reduction in antral follicle' size (238.61±19.01 µm vs 131.95±19.01 µm, P=0.001).
Conclusion
Oral PS-NPs exposure in female mice appears to induce toxicity by reducing antral follicles size, increasing the estrous cycle length, and decreasing progesterone levels which may result in anovulation and different reproductive issues, such as infertility and polycystic ovary syndrome (PCOS). The effect of PS-NPs on infertility along with NPs’ mechanism of action in female reproductive system should be investigated in future studies.ThesisMaster of Science (MSc)Plastics in the environment break down into smaller particles called micro- and nanoplastics. These plastic particles are pollutants present in the aquatic and terrestrial environments entering every level of the food chain and ultimately reaching humans, yet few studies have examined the effects of nanoplastics on human health. A recent World Health Organization (WHO) report on nanoplastics has stressed the urgent need for toxicological studies to assess potential human health effects. Therefore, this study examined the effect of nanoplastics on the female reproductive system. This study was carried out in female mice exposed orally to a solution containing a vehicle control (water) and two different concentrations of nanoplastics (100 and 1,000 µg/l). Exposure occurred daily for a period of 29 days. At the conclusion of the study the mice were humanly euthanized with their blood and reproductive tissues collected for laboratory analysis. Results showed that nanoplastics exposure resulted in irregular reproductive cycle in mice along with a decrease in antral follicle size and progesterone levels which are indicators of anovulation and can lead to disorders, such as infertility and polycystic ovary syndrome (PCOS) which should be further investigated in future studies
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
