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2.
J Hosp Infect ; 104(3): 336-343, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31545991

ABSTRACT

BACKGROUND: The reliability of N95 filtering facepiece respirators (FFRs) depends on correct fitting. The perceived usability of FFRs is equally important because discomfort during usage may affect compliance. Body movements during nursing procedures may also increase the risk of face seal leakage. AIM: To evaluate the mask fit and usability of the best-fitting 3M N95 FFR and the nanofibre N95 FFR before and after nursing procedures. The physical properties of these FFRs were also examined. METHODS: This experimental study had a one-group multiple comparison design. In total, 104 nursing students participated, and performed nursing procedures for 10 min when wearing the best-fitting 3M FFR and the nanofibre FFR. Mask fit and perceived usability of the FFRs were evaluated. FINDINGS: More participants failed to obtain a fit factor ≥100 when using the best-fitting 3M FFR than when wearing the nanofibre FFR (33.7% vs 21.2%) after the procedures (P=0.417). The nanofibre FFR also demonstrated higher usability than the 3M FFRs in terms of facial heat, breathability, facial pressure, speech intelligibility, itchiness, difficulty of maintaining the mask in place, and comfort level (P<0.001). The nanofibre FFR was also lighter, thinner and had slightly higher bacterial filtration efficiency than the 3M FFRs. CONCLUSION: The nanofibre FFR demonstrated significantly better usability than the 3M FFRs. None of the respirators were able to provide consistent protection for the wearer, as detected by face seal leakage after performing nursing procedures. Further improvement in the prototype design is needed to increase compliance and ensure the respiratory protection of users.


Subject(s)
Equipment Design , Occupational Exposure/prevention & control , Respiratory Protective Devices , Students, Nursing , Equipment Design/standards , Equipment Failure Analysis , Female , Filtration , Humans , Inhalation Exposure/prevention & control , Male , Materials Testing , Nanofibers , Respiratory Protective Devices/standards
3.
Haemophilia ; 22 Suppl 3: 6-16, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27348396

ABSTRACT

This guideline was developed to identify evidence-based best practices in haemophilia care delivery, and discuss the range of care providers and services that are most important to optimize outcomes for persons with haemophilia (PWH) across the United States. The guideline was developed following specific methods described in detail in this supplement and based on the GRADE (Grading of Recommendations, Assessment, Development and Evaluation approach). Direct evidence from published literature and the haemophilia community, as well as indirect evidence from other chronic diseases, were reviewed, synthesized and applied to create evidence-based recommendations. The Guideline panel suggests that the integrated care model be used over non-integrated care models for PWH (conditional recommendation, moderate certainty in the evidence). For PWH with inhibitors and those at high risk for inhibitor development, the same recommendation was graded as strong, with moderate certainty in the evidence. The panel suggests that a haematologist, a specialized haemophilia nurse, a physical therapist, a social worker and round-the-clock access to a specialized coagulation laboratory be part of the integrated care team, over an integrated care team that does not include all of these components (conditional recommendation, very low certainty in the evidence). Based on available evidence, the integrated model of care in its current structure, is suggested for optimal care of PWH. There is a need for further appropriately designed studies that address unanswered questions about specific outcomes and the optimal structure of the integrated care delivery model in haemophilia.


Subject(s)
Disease Management , Hemophilia A/therapy , Autoantibodies/blood , Delivery of Health Care/methods , Delivery of Health Care/organization & administration , Delivery of Health Care/standards , Evidence-Based Medicine , Hemophilia A/pathology , Humans , Research , Risk Factors
4.
Haemophilia ; 22 Suppl 3: 17-22, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27348397

ABSTRACT

BACKGROUND: Rigorous and transparent methods are necessary to develop clinically relevant and evidence-based practice guidelines. We describe the development of the National Hemophilia Foundation-McMaster Guideline on Care Models for Haemophilia Management, which addresses best practices in haemophilia care delivery. METHODS: We assembled a Panel of persons with haemophilia (PWH), parents of PWH, clinical experts and guideline methodologists. Conflicts of interest were disclosed and managed throughout. Panel members and key stakeholders were surveyed to develop the guideline questions and identify patient-important outcomes. Systematic reviews of the literature were conducted for all factors important in decision-making: benefits and harms; patient values and preferences; resource implications; acceptability; equity; and feasibility. We used the GRADE approach to create evidence profiles to evaluate the evidence and present key results. Evidence to Decision frameworks were created to guide the Panel in making evidence-based recommendations. When evidence was very low quality or not available, evidence from other chronic disease populations was presented to the Panel to inform the recommendations. Additionally, we systematically pooled observations from experts, and conducted qualitative interviews exploring key stakeholder experiences and perspectives. The Panel made recommendations for each guideline question and elaborated on research priorities, implementation considerations, and monitoring. Final recommendations were circulated for public and peer review. CONCLUSIONS: Despite the paucity of high-quality evidence typical of a rare condition such as haemophilia, we successfully applied a rigorous and transparent methodology based on GRADE to develop an evidence-based clinical practice guideline.


Subject(s)
Delivery of Health Care/methods , Disease Management , Hemophilia A/therapy , Delivery of Health Care/standards , Evidence-Based Medicine , Guidelines as Topic , Humans
5.
Haemophilia ; 22 Suppl 3: 23-30, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27348398

ABSTRACT

INTRODUCTION: Care for persons with haemophilia (PWH) is most commonly delivered through the integrated care model used by Hemophilia Treatment Centers (HTCs). Although this model is widely accepted as the gold standard for the management of haemophilia; there is little evidence comparing different care models. AIM: We performed a qualitative study to gain insight into issues related to outcomes, acceptability, equity and feasibility of different care models operating in the US. METHODS: We used a qualitative descriptive approach with semi-structured interviews. Purposive sampling was used to recruit individuals with experience providing or receiving care for haemophilia in the US through either an integrated care centre, a specialty pharmacy or homecare company, or by a specialist in a non-specialized centre. Persons with haemophilia, parents of PWH aged ≤18, healthcare providers, insurance company representatives and policy developers were invited to participate. RESULTS AND CONCLUSIONS: Twenty-nine interviews were conducted with participants representing 18 US states. Participants in the study sample had experience receiving or providing care predominantly within an HTC setting. Integrated care at HTCs was highly acceptable to participants, who appreciated the value of specialized, expert care in a multidisciplinary team setting. Equity and feasibility issues were primarily related to health insurance and funding limitations. Additional research is required to document the impact of care on health and psychosocial outcomes and identify effective ways to facilitate equitable access to haemophilia treatment and care.


Subject(s)
Delivery of Health Care/standards , Disease Management , Hemophilia A/therapy , Health Personnel , Humans , Insurance, Health , Interviews as Topic , Patient Acceptance of Health Care , Perception , Qualitative Research , United States
6.
Haemophilia ; 22 Suppl 3: 41-50, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27348400

ABSTRACT

BACKGROUND: Integrated care models have been adopted for individuals with chronic conditions and for persons with rare diseases, such as haemophilia. OBJECTIVE: To summarize the evidence from reviews for the effects of integrated multidisciplinary care for chronic conditions in adults and to provide an example of using this evidence to make recommendations for haemophilia care. SEARCH METHODS: We searched MEDLINE, EMBASE, CINAHL and Cochrane Database of Systematic Reviews up to January 2016, and reviewed reference lists of retrieved papers. SELECTION CRITERIA: Systematic reviews of at least one randomized study, on adults with non-communicable chronic conditions. DATA COLLECTION AND ANALYSIS: Two investigators independently assessed eligibility and extracted data. Quality of reviews was assessed using ROBIS, and the evidence assessed using GRADE. RESULTS: We included seven reviews reporting on three chronic conditions. We found low to high quality evidence. Integrated care results in a reduction in mortality; likely a reduction in emergency visits and an improvement in function; little to no difference in quality of life, but shorter hospital stays; and may result in little to no difference in missed days of school or work. No studies reported educational attainment, or patient adherence and knowledge. When used for haemophilia, judgment about the indirectness of the evidence was driven by disease, intervention or outcome characteristics. CONCLUSION: This overview provides the most up to date evidence on integrated multidisciplinary care for chronic conditions in adults, and an example of how it can be used for guidelines in rare diseases.


Subject(s)
Disease Management , Rare Diseases/therapy , Adult , Chronic Disease , Databases, Factual , Delivery of Health Care , Emergency Treatment , Hemophilia A/mortality , Hemophilia A/pathology , Hemophilia A/therapy , Humans , Length of Stay , Quality of Life , Rare Diseases/pathology
7.
Haemophilia ; 22 Suppl 3: 31-40, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27348399

ABSTRACT

BACKGROUND: Haemophilia care is commonly provided via multidisciplinary specialized management. To date, there has been no systematic assessment of the impact of haemophilia care delivery models on patient-important outcomes. OBJECTIVE: To conduct a systematic review of published studies assessing the effects of the integrated care model for persons with haemophilia (PWH). SEARCH METHODS: We searched MEDLINE, EMBASE and CINAHL up to April 22, 2015, contacted experts in the field, and reviewed reference lists. SELECTION CRITERIA: Randomized and non-randomized studies of PWH or carriers, focusing mainly on the assessment of care models on delivery. DATA COLLECTION AND ANALYSIS: Two investigators independently screened title, abstract, and full text of retrieved articles for inclusion. Risk of bias and overall quality of evidence was assessed using Cochrane's ACROBAT-NRSI tool and GRADE respectively. Relative risks, mean differences, proportions, and means and their variability were calculated as appropriate. RESULTS: 27 non-randomized studies were included: eight comparative and 19 non-comparative studies. We found low- to very low-quality evidence that in comparison to other models of care, integrated care may reduce mortality, hospitalizations and emergency room visits, may lead to fewer missed days of school and work, and may increase knowledge seeking. CONCLUSION: Our comprehensive review found low- to very low-quality evidence from a limited number of non-randomized studies assessing the impact of haemophilia care models on some patient-important outcomes. While the available evidence suggests that adoption of the integrated care model may provide benefit to PWH, further high-quality research in the field is needed.


Subject(s)
Disease Management , Hemophilia A/therapy , Models, Nursing , Clinical Trials as Topic , Databases, Factual , Delivery of Health Care/methods , Delivery of Health Care/standards , Hemophilia A/mortality , Hemophilia A/pathology , Humans , Length of Stay
8.
Mol Hum Reprod ; 19(2): 57-71, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23155044

ABSTRACT

Aberrant activation of the Wnt/ß-catenin pathway occurs in cancers. This review presents several important cancer-related aspects of Wnt/ß-catenin signalling relevant to the epididymis, provides evidence of such epididymal gene expression and suggests a new direction for further research. The data presented here indicate that besides containing many Wnt/ß-catenin-pathway components, the normal adult human epididymis expresses much more ß-catenin than the colorectal carcinoma cell line HCT116, which possesses elevated ß-catenin expression. The low cancer incidence in the epididymis may be due to factors present in the human epididymis that regulate this oncogenic Wnt/ß-catenin pathway, including (i) 14 of 17 secreted pathway inhibitors, (ii) the majority of the micro-RNAs known to target this pathway, (iii) plasma membrane-associated E-cadherin and CEACAM1 that anchor ß-catenin, preventing its availability for nuclear entry and oncogenic transcriptional activity, (iv) the recently identified membrane-located tumourigenesis inhibitors RNF43 and ZNRF3 that mediate the degradation of the Wnt receptor components Fzds and Lrp5/6 and (v) nuclear KLF4, which competes with TCF for ß-catenin, limiting its transcriptional activity and stabilizing telomeres, thereby reducing mutation incidence. The above regulatory factors expressed by the human epididymis, and the absence of androgen receptor translocation known to promote nuclear translocation of ß-catenin in tumourigenesis in an animal model, may act synergistically to provide hostility in different cell compartments towards tumour formation. The lack of evidence for ß-catenin in epididymal nuclei is noteworthy. Studying this phenomenon may help reveal the mechanisms underlying oncogenic Wnt/ß-catenin signalling and shed new light on cancer therapy and prevention.


Subject(s)
Epididymis/metabolism , Neoplasms/metabolism , Wnt Signaling Pathway/physiology , Humans , Kruppel-Like Factor 4 , Male , Wnt Signaling Pathway/genetics
9.
Phys Rev E Stat Nonlin Soft Matter Phys ; 84(4 Pt 2): 046104, 2011 Oct.
Article in English | MEDLINE | ID: mdl-22181224

ABSTRACT

Many innovations are inspired by past ideas in a nontrivial way. Tracing these origins and identifying scientific branches is crucial for research inspirations. In this paper, we use citation relations to identify the descendant chart, i.e., the family tree of research papers. Unlike other spanning trees that focus on cost or distance minimization, we make use of the nature of citations and identify the most important parent for each publication, leading to a treelike backbone of the citation network. Measures are introduced to validate the backbone as the descendant chart. We show that citation backbones can well characterize the hierarchical and fractal structure of scientific development, and lead to an accurate classification of fields and subfields.

10.
Phys Rev E Stat Nonlin Soft Matter Phys ; 83(1 Pt 2): 016105, 2011 Jan.
Article in English | MEDLINE | ID: mdl-21405742

ABSTRACT

We introduce a simple model to study movie competition in recommender systems. Movies of heterogeneous quality compete against each other through viewers' reviews and generate interesting dynamics at the box office. By assuming mean-field interactions between the competing movies, we show that the runaway effect of popularity spreading is triggered by defeating the average review score, leading to box-office hits: Popularity rises and peaks before fade-out. The average review score thus characterizes the critical movie quality necessary for transition from box-office bombs to blockbusters. The major factors affecting the critical review score are examined. By iterating the mean-field dynamical equations, we obtain qualitative agreements with simulations and real systems in the dynamical box-office forms, revealing the significant role of competition in understanding box-office dynamics.

11.
Reproduction ; 139(1): 209-16, 2010 Jan.
Article in English | MEDLINE | ID: mdl-19812234

ABSTRACT

AQP11 is one of the latest aquaporin (AQP) family members found, which differs from the other AQPs by its intracellular localisation and unusual water pore nucleotides with unclear function. Despite the highest mRNA expression among organs having been reported in the testis, the testicular molecule has not been studied in detail. Immunohistochemistry of rat adult testis localised AQP11 to the elongated spermatids (ES) and no other cell types except residual bodies inside Sertoli cells. It was absent from early ES at least until stage 13, and after a first diffuse appearance in the caudal cytoplasm became concentrated in intracellular organelles by stage 17, was strongest in vesicles in the anterior cytoplasm at the final ES stages and appeared in residual bodies. Staining was detected on the distal quarter of the sperm tail only immediately before spermiation. A similar localisation was found in the mouse and developmental profiles for both the open reading frame mRNA and protein expression in 8-50 dpp testis pinpointed its first appearance coinciding with late stage ES. Sequencing of PCR products of testicular Aqp11 containing the open reading frames confirmed a full match with GenBank databases for rat, mouse and human. Western blotting revealed two or more molecular forms with the 26/27 kDa species dominating in the rat/mouse testis and the 33/34 kDa form selectively allocated to the spermatozoa. In view of intracellular vacuolation leading to polycystic kidney in Aqp11-null mice, a possible role of testicular AQP11 in the recycling of surplus cytoplasmic components of the ES and sustaining Sertoli cell capacity in the support of spermatogenesis was discussed.


Subject(s)
Aquaporins/metabolism , Cytoplasm/metabolism , Spermatids/metabolism , Testis/metabolism , Animals , Aquaporins/chemistry , Aquaporins/genetics , DNA, Complementary/chemistry , Gene Expression Regulation, Developmental , Humans , Male , Mice , Organ Specificity , Protein Transport , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Sexual Development , Spermatids/ultrastructure , Spermatogenesis , Spermatozoa/cytology , Spermatozoa/metabolism , Testis/cytology , Testis/physiology
12.
Int J Androl ; 33(4): 629-41, 2010 Aug 01.
Article in English | MEDLINE | ID: mdl-19840149

ABSTRACT

Despite the high water-permeability of human spermatozoa, little is known about the identity and the role of aquaporins (AQP) in them or germ cells. Using ejaculates from donors, sperm AQPs were identified by western blotting followed by the analysis of mRNA with RT-PCR. Protein expression in the testis and spermatozoa was localized by immunocytochemistry. Inhibitors were used to investigate the involvement of aquaporins in water transport when ejaculated spermatozoa were swollen in medium mimicking uterine hypo-osmolality by quinine that blocks volume regulation. Sperm AQP7 and AQP8 in 39 infertile patients and 11 healthy donors were quantified by flow cytometry. AQP1 was absent from spermatozoa. Sperm and testicular AQP7-9 had nucleotide sequences identical to those of somatic cells but AQP8 mRNA also showed shorter variants. AQP7 was expressed abundantly by round and elongated spermatids and ejaculated spermatozoa, AQP8 by all germ cells and spermatozoa, and AQP9 rarely by spermatocytes or Sertoli cells. Protein bands showed specificity by western blotting for AQP7 and AQP8 but not AQP9. The absence of sperm AQP9 was further suggested by the ineffectiveness of its inhibitor phloretin in blocking quinine-induced swelling, but HgCl(2,) which inhibits AQP8, was effective. Sperm AQP7 expression was correlated with progressive motility and was lower in patients than in donors. Sperm AQP8 expression was inversely correlated with the extent of sperm coiling, which is a swelling phenomenon, but showed no difference between patients and donors. In conclusion, AQP7 and AQP8 were identified in human spermatozoa and could play a role in glycerol metabolism and water transport respectively.


Subject(s)
Aquaporins/metabolism , Spermatozoa/metabolism , Testis/metabolism , Aquaporins/antagonists & inhibitors , Aquaporins/biosynthesis , Ejaculation/physiology , Humans , Infertility, Male/metabolism , Male , Mercuric Chloride/pharmacology , RNA, Messenger/metabolism , Sertoli Cells/metabolism , Spermatids/metabolism , Spermatocytes/metabolism
13.
Phys Rev E Stat Nonlin Soft Matter Phys ; 80(2 Pt 1): 021102, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19792072

ABSTRACT

We investigate a model of transportation networks with nonlinear elements which may represent local shortage of resources. Frustrations arise from competition for resources. When the initial resources are uniform, different regimes with discrete fractions of satisfied nodes are observed, resembling the Devil's staircase. We demonstrate how functional recursions are converted to simple recursions of probabilities. Behaviors similar to those in the vertex cover or close packing problems are found. When the initial resources are bimodally distributed, increases in the fraction of rich nodes induce a glassy transition, entering an algorithmically hard regime.

14.
Hum Reprod ; 24(6): 1288-95, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19221095

ABSTRACT

BACKGROUND: There is no systematic study on coiled sperm in semen, although they are commonly observed. This work characterizes coiled sperm in infertile men to understand the clinical implications and investigate the possible cause by osmotic swelling. METHODS: Coiled sperm in semen from 439 infertile patients were quantified and their ultrastructure examined by electron microscopy. Hypo-osmotic swelling (HOS) and demembranation tests were performed to elucidate the nature of the coiling. RESULTS: Semen from patients contained overall 3% of sperm with head-in-coil (HIC) and 8% other coiled forms, with 12% of patients having 20% or more such sperm. The percentage of coiled sperm (but not HIC) was correlated with age (R = 0.26, P = 0.003) and the epididymal secretory marker neutral alpha-glucosidase (R = 0.16, P < 0.001), and associated with heavy smoking and varicocele. Electron microscopy revealed coiling of tail filaments within the plasma membrane, resembling HOS. Some seminal coiled sperm and most sperm freshly coiled upon HOS could be opened by demembranation, while those that could not be opened were probably fixed in position by oxidation, which occurred more frequently in patients than semen donors. CONCLUSIONS: Sperm coiling in semen is common and independent of sperm quantity or hormonal status. Whereas HIC may have a genetic background, other coiled forms may be associated with a hostile endogenous milieu in the epididymis that causes swelling.


Subject(s)
Infertility, Male/pathology , Sperm Tail/diagnostic imaging , Sperm Tail/pathology , Varicocele/pathology , Adolescent , Adult , Cell Membrane/diagnostic imaging , Cell Membrane/metabolism , Cell Membrane/pathology , Hormones/blood , Humans , Infertility, Male/metabolism , Male , Microscopy, Electron , Middle Aged , Osmolar Concentration , Osmosis , Smoking , Sperm Tail/metabolism , Ultrasonography , Varicocele/metabolism , Young Adult
15.
Int J Androl ; 32(3): 242-54, 2009 Jun.
Article in English | MEDLINE | ID: mdl-18070047

ABSTRACT

In the treatment of male infertility by intra-cytoplasmic injection of spermatozoa (ICSI) extracted from testicular tissue (TESE), the high incidence of negative TESE outcome calls for non-invasive prognostic methods. Literature suggests that seminal haploid germ cell detection could be one. For this purpose, a multi-parametric stringent flow cytometric method was applied to 50 TESE patients for the quantification of ejaculated germ cells. Cells from 50 ejaculates were identified and quantified as spermatozoa (HC, highly condensed), round spermatids (1N), primary spermatocytes (SPC) (4N) or diploid cells (2N, including somatic and non-testicular cells) by their DNA and mitochondria staining and laser scatter characteristics, and compared with testicular biopsy histology and TESE outcome. Whereas 96% of patients displayed a diploid peak in the distribution histograms, the HC, 1N and 4N peaks were absent from the majority of samples. In 13 ejaculates, either a HC or 1N or 4N peak, or a combination of these, was discernible. Although seminal germ cell numbers bore no overall association with elongated spermatids (ES) in histology or spermatozoa retrieval in TESE outcome, 4N cells per ejaculate were correlated with the percentage of tubule sections showing SPC as the most advanced germ cells. The incidence of HC peaks was higher in patients showing some ES in histology or sperm retrieval than in the sperm-negative groups. In groups with suspected obstruction showing nearly full spermatogenesis and maximal sperm retrieval, there was no incidence of a HC peak. Germ cell peaks were associated with germ cell degeneration noted in testicular histology. In conclusion, seminal germ cells cannot provide good prognosis for TESE, although their presence could indicate the spermatogenic activity in the testis.


Subject(s)
Azoospermia/pathology , Semen/cytology , Spermatozoa/pathology , Testis/pathology , Biopsy , Flow Cytometry , Follicle Stimulating Hormone/blood , Humans , Infertility, Male/pathology , Luteinizing Hormone/blood , Male , Prognosis , Prolactin/blood , Semen Analysis , Sperm Injections, Intracytoplasmic/methods , Testosterone/blood
16.
Reproduction ; 136(4): 401-10, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18614623

ABSTRACT

The nature of the membrane channels mediating water transport in murine spermatozoa adjusting to anisotonic conditions was investigated. The volume of spermatozoa subjected to physiologically relevant hypotonic conditions either simultaneously, or after isotonic pre-incubation, with putative water transport inhibitors was monitored. Experiments in which quinine prevented osmolyte efflux, and thus regulatory volume decrease (RVD), revealed whether water influx or efflux was being inhibited. There was no evidence that sodium-dependent solute transporters or facilitative glucose transporters were involved in water transport during RVD of murine spermatozoa since phloretin, cytochalasin B and phloridzin had no effect on volume regulation. However, there was evidence that Hg(2+)- and Ag(+)-sensitive channels were involved in water transport and the possibility that they include aquaporin 8 is discussed. Toxic effects of these heavy metals were ruled out by evidence that mitochondrial poisons had no such effect on volume regulation.


Subject(s)
Ion Channels/metabolism , Spermatozoa/metabolism , Water/metabolism , Animals , Biological Transport , Cell Size/drug effects , Cell Survival/drug effects , Cells, Cultured , Culture Media , Cytochalasin D/pharmacology , Diuretics/pharmacology , Furosemide/pharmacology , Hypotonic Solutions , Male , Mercury/toxicity , Mice , Mice, Inbred C57BL , Nucleic Acid Synthesis Inhibitors/pharmacology , Phloretin/pharmacology , Phlorhizin/pharmacology , Potassium Channel Blockers/pharmacology , Quinine/pharmacology , Rotenone/pharmacology , Silver/toxicity , Sodium Azide/pharmacology , Tetraethylammonium/pharmacology , Time , Uncoupling Agents/pharmacology
17.
Phys Rev E Stat Nonlin Soft Matter Phys ; 77(2 Pt 2): 026107, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18352090

ABSTRACT

We consider models of financial markets in which all parties involved find incentives to participate. Strategies are evaluated directly by their virtual wealth. By tuning the price sensitivity and market impact, a phase diagram with several attractor behaviors resembling those of real markets emerge, reflecting the roles played by the arbitrageurs and trendsetters, and including a phase with irregular price trends and positive sums. The positive sumness of the players' wealth provides participation incentives for them. Evolution and the bid-ask spread provide mechanisms for the gain in wealth of both the players and market makers. New players survive in the market if the evolutionary rate is sufficiently slow. We test the applicability of the model on real Hang Seng Index data over 20 years. Comparisons with other models show that our model has a superior average performance when applied to real financial data.

18.
Reproduction ; 135(5): 625-33, 2008 May.
Article in English | MEDLINE | ID: mdl-18304983

ABSTRACT

The permeability of murine cauda epididymidal spermatozoa was determined from the swelling caused by penetrating agents at isotonicity, which lies between 422 and 530 mmol/kg. Spermatozoa were permeable to a range of solutes with size <200 Da. Relative entry rates of cryoprotective agents (CPAs) were ethylene glycol approximately DMSO>propane-1,2-diol>glycerol>propane-1,3-diol. More polar compounds including major epididymal secretions were impermeant. None of the compounds entered spermatozoa through quinine-sensitive channels; rather, quinine increased the size of solute-swollen spermatozoa, suggesting that regulatory volume decrease and osmolyte loss occurred under these conditions. Volume responses to lowered osmolality revealed a greater volume-regulating ability of spermatozoa from the B6D2F1 strain than the C57BL6 strain. As the former strain displays better post-thaw fertility, their spermatozoa may have greater osmolyte loads enabling them to cope better with osmotic stress. Inadequate volume regulation, due to CPA-induced osmolyte loss, may affect post-thaw fertility. Knowing the permeability towards cryoprotectants will help to make a better choice of CPAs that are less damaging to sperm during cryopreservation.


Subject(s)
Cryoprotective Agents/pharmacology , Epididymis , Spermatozoa/drug effects , Animals , Cell Membrane Permeability/drug effects , Cryopreservation , Dimethyl Sulfoxide/pharmacology , Ethylene Glycol/pharmacology , Glycerol/pharmacology , Male , Mice , Mice, Inbred C57BL , Mice, Inbred Strains , Osmosis , Propylene Glycols/pharmacology , Semen Preservation , Species Specificity , Sperm Motility/drug effects
19.
Mol Reprod Dev ; 75(4): 659-68, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18157847

ABSTRACT

KCNE1, KCNA5 and KCNK5 have been identified, by using specific blockers, as K(+)-channels involved in sperm volume regulation under physiological conditions. All three channels were localised on the cytoplasmic droplets and tail of human ejaculated spermatozoa by fluorescence microscopy. Using flow cytometric quantification, KCNE1 was found to be present in 80% or more spermatozoa and KCNK5 in only about 20%, with KCNA5 expressed by 20-90% of cells. Whereas the extents of such protein expression did not differ statistically between semen donors and subfertile patients, the former group exhibited higher capacities for sperm volume regulation which were correlated with other sperm qualities including normal morphology and motile sperm number in the ejaculate. Channel identification was further confirmed at the protein level using Western blotting. RT-PCR analysis of testicular and sperm RNA of proven quality indicated the presence of Kcne1, Kcna5 and Kcnk5 transcripts. Subsequent sequencing of PCR products demonstrated that the nucleotide sequences of the entire encoding regions of Kcne1 and Kcnk5 were identical to those published in the database, whereas that of Kcna5 mRNA showed a single nucleotide synonymous deviation that agrees with the published genomic sequence. Quantitative real-time PCR analysis of sperm RNA revealed the amounts of Kcne1 > Kcna5 > Kcnk5, in the same order as for protein expression. Thus, KCNE1 is probably the major K(+)-channel involved in regulatory volume decrease in human spermatozoa, and channel activity is regulated beyond the extent of protein expression.


Subject(s)
Kv1.5 Potassium Channel/genetics , Potassium Channels, Tandem Pore Domain/genetics , Potassium Channels, Voltage-Gated/genetics , RNA, Messenger/genetics , Spermatozoa/physiology , Base Sequence , Cell Size , Flow Cytometry , Humans , Immunohistochemistry , Kv1.5 Potassium Channel/analysis , Kv1.5 Potassium Channel/physiology , Male , Molecular Sequence Data , Potassium Channels, Tandem Pore Domain/analysis , Potassium Channels, Tandem Pore Domain/physiology , Potassium Channels, Voltage-Gated/analysis , Potassium Channels, Voltage-Gated/physiology , RNA, Messenger/physiology , Reverse Transcriptase Polymerase Chain Reaction , Sperm Motility/physiology , Spermatozoa/chemistry , Spermatozoa/cytology , Testis/chemistry , Testis/physiology
20.
Curr Pharm Des ; 13(31): 3222-30, 2007.
Article in English | MEDLINE | ID: mdl-18045171

ABSTRACT

Spermatozoa produced in the testis undergo maturation in the epididymis which secretes an osmolyte-rich fluid that bathes the sperm cells. These cells need to maintain their volume after ejaculation when they first encounter hypo-osmolal environments of accessory gland fluids and later within the female tract. If they do not, they experience swelling that is manifested in flagellar angulation that prevents their passage through cervical mucus or the uterotubal junction and they never reach the oocytes. This is a cause of male infertility in domestic species and certain infertile transgenic mice in which flagellar angulation has been shown to indicate cell swelling as a consequence of reduced epididymal provision of osmolytes. The reduced volume regulating ability of spermatozoa from subfertile boars and bulls has prompted study of volume regulation of spermatozoa as a possible cause of human male infertility. Understanding this process may make its manipulation possible and could suggest better sperm handling and storage techniques and thus provide therapy for infertile patients. On the other hand, volume regulation is a potential target for contraception if mimicking the conditions expressed by the "sterile studs" were possible. The evidence for the presence of ion channels probably responsible for regulatory volume decreases in spermatozoa is reviewed here that implicate voltage-gated potassium channels (especially Kv1.5 (KCNA5), minK (KCNE1) and TASK2 (KCNK5)) and the chloride channels CLCN3 and CLNS1A. The involvement of ion co-transporters in volume regulation of spermatozoa is also discussed.


Subject(s)
Chloride Channels/metabolism , Potassium Channels, Voltage-Gated/metabolism , Spermatozoa/metabolism , Animals , Contraceptive Agents/administration & dosage , Drug Delivery Systems , Humans , Infertility, Male/drug therapy , Infertility, Male/etiology , Ion Transport/physiology , Male , Potassium Channel Blockers/pharmacology , Specimen Handling
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