1,720,985 research outputs found
Seminal factor VII and factor VIIa: Supporting evidence for the presence of an active tissue factor dependent coagulation pathway in human
No full textHuman semen spontaneously coagulates into a semisolid mass and then wholly liquefies in a process that may have some similarity to that of normal blood. This well described phenomenon is referred to as coagulation and liquefaction of semen. Besides other active components of the haemostatic system, semen contains a significant amount of functional tissue factor (TF). However, TF needs factor (F)VII in order to exert it actions. In this study, we assessed human semen for the presence of FVII and FVIIa, and related their levels to conventional fertility parameters. Using a functional, one stage, clotting assay based upon the prolongation of the prothrombin clotting time, using the ACL 300R analyser and an Imubind® FVIIa ELISA assay, FVII and FVIIa levels were measured in 97 semen specimens obtained from sub-fertile (sperm counts <20 × 106/mL), normally fertile (sperm counts ?20 × 106 but <60 × 106/mL), fertile sperm donors (sperm counts ?60 × 106/mL), vasectomized subjects and in a pooled normal semen parameters group (categorization into groups was based on the World Health Organization guidelines on fertility criteria). In addition, conventional semen parameters were analysed on all semen samples. Both FVII and FVIIa were quantifiable in human semen. The mean levels of FVII and FVIIa were 4.4 IU/dL and 12 ng/mL respectively. Despite the observed variations of FVIIa levels in the studied groups they did not meet statistical significance when the groups were tested against each other. However, seminal FVIIa levels showed a significant positive association with semen liquefaction time, sperm motility and semen volume. The anti-sperm antibodies and sperm-agglutination groups were also associated with raised seminal FVIIa levels. We observed no significant relationship between FVIIa levels and total sperm concentration, sperm count per mL (sperm density), sperm progression and days of sexual abstinence. This study demonstrates that human semen contains appreciable amounts of FVII and FVIIa. It is possible to quantify these using commercially available assays. There also appears to be a direct correlation between the levels of these factors and certain seminal parameters. This finding reinforces the concept of an active clotting system in human semen, by establishing the missing link in the activation of a TF-dependent pathway
Seminal hemostatic factors: then and now
No full textHuman semen spontaneously coagulates and subsequently liquefies following ejaculation. The exact reasons for this phenomenon are not entirely understood. Research has resulted in the discovery of several seminal proteins that are already known from another major domain of human physiology (i.e., blood coagulation and fibrinolysis). Some believe that regulation of seminal coagulation and fibrinolytic liquefaction may bear analogies to the well-described pathways operational in blood. We here attempt to summarize the subject, revisiting earlier findings and covering the more recent and extensive data on hemostatically functional seminal proteins, including the findings of our own group. Evidence for the existence of each key hemostatic factor in semen is presented along with any correlation with indices of male fertility. Several probably possess alternative functions including anti-inflammatory action, aiding sperm capacitation and classic hemostasis following intercourse-induced bleeding. Established mechanisms such as the high molecular weight seminal vesicle system are also considered as potentially interacting with conventional hemostatic pathways to regulate seminal coagulation and liquefaction. Although our grasp of this subject continues to evolve, there still remain many unanswered questions. A more complete understanding may one day prove useful in designing technologies for improved diagnostics in male infertility and potentially aiding assisted human reproductive therapie
Seminal thrombin activatable fibrinolysis inhibitor: a regulator of liquefaction
No full textSeveral active components of the haemostatic system have been identified in human semen. Here we investigated the presence of thrombin-activatable fibrinolysis inhibitor (TAFI) in seminal plasma. Using an enzyme-linked immunosorbent assay, TAFI levels were measured in 36 semen specimens obtained from subfertile, normally fertile, fertile sperm donor and vasectomized individuals. TAFI was detectable in human semen. Its levels were highest in vasectomized individuals compared with the other groups, including a pooled normal semen parameter stratification group (by World Health Organization criteria). This elevation in the vasectomy group was found to be statistically significant in comparison with the normally fertile (P < 0.01) and the pooled normal semen parameter groups (P < 0.05). Seminal TAFI levels showed a significant positive correlation with total sperm count and sperm density. In contrast, a negative association was observed with semen volume, days of sexual abstinence and liquefaction time. The highly motile sperm group showed low TAFI levels. Our results establish the presence of TAFI in seminal plasma with a probable role in the protection of the seminal clot against lysis. It also suggests a downstream (post-testicular) source for its production. This reinforces the involvement of the conventional haemostatic system in the coagulation and liquefaction properties of human seme
Prostate cells exposed to lycopene in vitro liberate lycopene-enriched exosomes
No full textOBJECTIVES: To investigate whether cellular exosomes liberated by prostatic cell lines in culture might be acting as the transport vehicles for the dietary antioxidant lycopene, known to be sequestered in the prostate gland and to reduce the risk of developing benign prostatic hyperplasia (BPH) and prostate cancer; its subsequent secretion into seminal plasma also confers protection to spermatozoa against oxidative free-radical damage.MATERIALS AND METHODS: Using benign and malignant human prostatic cell culture models, we assessed the role that their exosomes (the putative in vitro analogues of prostasomes) might have in the transport of lycopene.RESULTS: Cells exposed to lycopene in vitro accumulated the molecule and secrete lycopene-enriched exosomes. This continued after the lycopene exposure was stopped. Extraction of lycopene from the exosomes, followed by high-performance liquid chromatography, confirmed nanogram quantities of lycopene per milligram of exosomal protein. Packaging into exosomes for export resulted in reduced degradation of this labile antioxidant, and therefore maximized the effectiveness of delivery to the sites of action.CONCLUSION: These results support the likelihood that these organelles act as the transport vehicles for this important lipophilic agent known to have a role in the chemoprevention of various urological pathologies such as BPH, prostate cancer and male infertility.<br/
sj-docx-1-pie-10.1177_09544089221150703 - Supplemental material for Investigations on erosion performance of carbon fiber–epoxy-based composite adhesion on 16Cr5Ni steel
No full textSupplemental material, sj-docx-1-pie-10.1177_09544089221150703 for Investigations on erosion performance
of carbon fiber–epoxy-based composite adhesion on 16Cr5Ni steel by Mithlesh Sharma, Deepak Kumar Goyal, Anuj Bansal, Anil Kumar Singla, Neel Kanth Grover, Munish Kumar Gupta and Navneet Khanna in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
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
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