144 research outputs found

    A comparison of human chorionic gonadotropin and luteinizing hormone releasing hormone on the induction of spermiation and amplexus in the American toad (Anaxyrus americanus).

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    BACKGROUND: Captive breeding programs for endangered amphibian species often utilize exogenous hormones for species that are difficult to breed. The purpose of our study was to compare the efficacy of two different hormones at various concentrations on sperm production, quantity and quality over time in order to optimize assisted breeding. METHODS: Male American toads (Anaxyrus americanus) were divided into three separate treatment groups, with animals in each group rotated through different concentrations of luteinizing hormone releasing hormone analog (LHRH; 0.1, 1.0, 4.0 and 32 micrograms/toad), human chorionic gonadotropin (hCG; 50, 100, 200, and 300 IU), or the control over 24 hours. We evaluated the number of males that respond by producing spermic urine, the sperm concentration, percent motility, and quality of forward progression. We also evaluated the effects of hCG and LHRH on reproductive behavior as assessed by amplexus. Data were analyzed using the Generalized Estimating Equations incorporating repeated measures over time and including the main effects of treatment and time, and the treatment by time interaction. RESULTS: The hormone hCG was significantly more effective at stimulating spermiation in male Anaxyrus americanus than LHRH and showed a dose-dependent response in the number of animals producing sperm. At the most effective hCG dose (300 IU), 100% of the male toads produced sperm, compared to only 35% for the best LHRH dose tested (4.0 micrograms). In addition to having a greater number of responders (P < 0.05), the 300 IU hCG treatment group had a much higher average sperm concentration (P < 0.05) than the treatment group receiving 4.0 micrograms LHRH. In contrast, these two treatments did not result in significant differences in sperm motility or quality of forward progressive motility. However, more males went into amplexus when treated with LHRH vs. hCG (90% vs. 75%) by nine hours post-administration. CONCLUSION: There is a clear dichotomy between the two hormones' physiological responses on gamete production and stimulation of amplexus. Understanding how these two hormones influence physiology and reproductive behaviors in amphibians will have direct bearing on establishing similar breeding protocols for endangered species

    Resistance to acid attack, abrasion and leaching behavior of alkali-activated mine waste binders

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    This paper report results of a research project on the development of alkali-activated binders using mine wastes. Abrasion and acid resistance of two ordinary Portland cement (OPC) strength class concrete mixtures (C20/25 and C30/37) and several mine waste (MW) mixtures were compared. This study indicates that MW binders possess higher acid and abrasion resistance than OPC based concrete mixtures.The leaching assessment of the MW binders shows it can be considered an inert material which indicates that it could be used as a building material

    Accumulation and transport of microbial-size particles in a pressure protected model burn unit: CFD simulations and experimental evidence

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    <p>Abstract</p> <p>Background</p> <p>Controlling airborne contamination is of major importance in burn units because of the high susceptibility of burned patients to infections and the unique environmental conditions that can accentuate the infection risk. In particular the required elevated temperatures in the patient room can create thermal convection flows which can transport airborne contaminates throughout the unit. In order to estimate this risk and optimize the design of an intensive care room intended to host severely burned patients, we have relied on a computational fluid dynamic methodology (CFD).</p> <p>Methods</p> <p>The study was carried out in 4 steps: i) patient room design, ii) CFD simulations of patient room design to model air flows throughout the patient room, adjacent anterooms and the corridor, iii) construction of a prototype room and subsequent experimental studies to characterize its performance iv) qualitative comparison of the tendencies between CFD prediction and experimental results. The Electricité De France (EDF) open-source software <it>Code_Saturne</it><sup>® </sup>(<url>http://www.code-saturne.org</url>) was used and CFD simulations were conducted with an hexahedral mesh containing about 300 000 computational cells. The computational domain included the treatment room and two anterooms including equipment, staff and patient. Experiments with inert aerosol particles followed by time-resolved particle counting were conducted in the prototype room for comparison with the CFD observations.</p> <p>Results</p> <p>We found that thermal convection can create contaminated zones near the ceiling of the room, which can subsequently lead to contaminate transfer in adjacent rooms. Experimental confirmation of these phenomena agreed well with CFD predictions and showed that particles greater than one micron (i.e. bacterial or fungal spore sizes) can be influenced by these thermally induced flows. When the temperature difference between rooms was 7°C, a significant contamination transfer was observed to enter into the positive pressure room when the access door was opened, while 2°C had little effect. Based on these findings the constructed burn unit was outfitted with supplemental air exhaust ducts over the doors to compensate for the thermal convective flows.</p> <p>Conclusions</p> <p>CFD simulations proved to be a particularly useful tool for the design and optimization of a burn unit treatment room. Our results, which have been confirmed qualitatively by experimental investigation, stressed that airborne transfer of microbial size particles via thermal convection flows are able to bypass the protective overpressure in the patient room, which can represent a potential risk of cross contamination between rooms in protected environments.</p

    Macrophages Help NK Cells to Attack Tumor Cells by Stimulatory NKG2D Ligand but Protect Themselves from NK Killing by Inhibitory Ligand Qa-1

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    Natural killer (NK) cells and their crosstalk with other immune cells are important for innate immunity against tumor. To explore the role of the interaction between NK cells and macrophages in the regulation of anti-tumor activities of NK cells, we here demonstrate that poly I:C-treated macrophages increased NK cell-mediated cytotoxicity against target tumor cells in NKG2D-dependent manner. In addition, IL-15, IL-18, and IFN-β secreted by poly I:C-treated macrophages are also involved in NKG2D expression and NK cell activation. Interestingly, the increase in expression of NKG2D ligands on macrophages induced a highly NK cell-mediated cytotoxicity against tumor cells, but not against macrophages themselves. Notably, a high expression level of Qa-1, a NKG2A ligand, on macrophages may contribute to such protection of macrophages from NK cell-mediated killing. Furthermore, Qa-1 or NKG2A knockdown and Qa-1 antibody blockade caused the macrophages to be sensitive to NK cytolysis. These results suggested that macrophages may activate NK cells to attack tumor by NKG2D recognition whereas macrophages protect themselves from NK lysis via preferential expression of Qa-1

    The 2022 symposium on dementia and brain aging in low- and middle-income countries: Highlights on research, diagnosis, care, and impact

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    \ua9 2024 The Authors. Alzheimer\u27s &amp; Dementia published by Wiley Periodicals LLC on behalf of Alzheimer\u27s Association.Two of every three persons living with dementia reside in low- and middle-income countries (LMICs). The projected increase in global dementia rates is expected to affect LMICs disproportionately. However, the majority of global dementia care costs occur in high-income countries (HICs), with dementia research predominantly focusing on HICs. This imbalance necessitates LMIC-focused research to ensure that characterization of dementia accurately reflects the involvement and specificities of diverse populations. Development of effective preventive, diagnostic, and therapeutic approaches for dementia in LMICs requires targeted, personalized, and harmonized efforts. Our article represents timely discussions at the 2022 Symposium on Dementia and Brain Aging in LMICs that identified the foremost opportunities to advance dementia research, differential diagnosis, use of neuropsychometric tools, awareness, and treatment options. We highlight key topics discussed at the meeting and provide future recommendations to foster a more equitable landscape for dementia prevention, diagnosis, care, policy, and management in LMICs. Highlights: Two-thirds of persons with dementia live in LMICs, yet research and costs are skewed toward HICs. LMICs expect dementia prevalence to more than double, accompanied by socioeconomic disparities. The 2022 Symposium on Dementia in LMICs addressed advances in research, diagnosis, prevention, and policy. The Nairobi Declaration urges global action to enhance dementia outcomes in LMICs

    Understanding resilience of female adolescents towards teenage pregnancy: a cross-sectional survey in Dar es Salaam, Tanzania

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    Abstract Background In Tanzania, teenage pregnancy rates are still high despite the efforts being made to reduce them. Not enough is known about how adolescents experience and cope with sexuality and teenage pregnancy. Over the past few decades, most studies have focused on vulnerability and risk among youth. The concept of ‘reproductive resilience’ is a new way of looking at teenage pregnancy. It shifts the perspective from a deficit-based to a strength-based approach. The study presented here aimed to identify factors that could contribute to strengthening the reproductive resilience of girls in Dar es Salaam, Tanzania. Methods Using a cross-sectional cluster sampling approach, 750 female adolescents aged 15–19 years were interviewed about how they mobilize resources to avoid or deal with teenage pregnancy. The main focus of the study was to examine how social capital (relations with significant others), economic capital (command over economic resources), cultural capital (personal dispositions and habits), and symbolic capital (recognition and prestige) contribute to the development of adolescent competencies for avoiding or dealing with teenage pregnancy and childbirth. Results A cumulative competence scale was developed to assess reproductive resilience. The cumulative score was computed based on 10 competence indicators that refer to the re- and pro-active mobilization of resources. About half of the women who had never been pregnant fell into the category, ‘high competence’ (50.9%), meaning they could get the information and support needed to avoid pregnancies. Among pregnant women and young mothers, most were categorized as ‘high competence’ (70.5%) and stated that they know how to avoid or deal with health problems that might affect them or their babies, and could get the information and support required to do so. Cultural capital, in particular, contributed to the competence of never-pregnant girls [OR = 1.80, 95% CI = 1.06 to 3.07, p = 0.029], pregnant adolescents and young mothers [OR = 3.33, 95% CI = 1.15 to 9.60, p = 0.026]. Conclusions The reproductive resilience framework provides new insights into the reproductive health realities of adolescent girls from a strength-based perspective. While acknowledging that teenage pregnancy has serious negative implications for many female adolescents, the findings presented here highlight the importance of considering girls’ capacities to prevent or deal with teenage pregnancy

    Utility of In Vivo Transcription Profiling for Identifying Pseudomonas aeruginosa Genes Needed for Gastrointestinal Colonization and Dissemination

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    Microarray analysis of Pseudomonas aeruginosa mRNA transcripts expressed in vivo during animal infection has not been previously used to investigate potential virulence factors needed in this setting. We compared mRNA expression in bacterial cells recovered from the gastrointestinal (GI) tracts of P. aeruginosa-colonized mice to that of P. aeruginosa in the drinking water used to colonize the mice. Genes associated with biofilm formation and type III secretion (T3SS) had markedly increased expression in the GI tract. A non-redundant transposon library in P. aeruginosa strain PA14 was used to test mutants in genes identified as having increased transcription during in vivo colonization. All of the Tn-library mutants in biofilm-associated genes had an attenuated ability to form biofilms in vitro, but there were no significant differences in GI colonization and dissemination between these mutants and WT P. aeruginosa PA14. To evaluate T3SS factors, we tested GI colonization and neutropenia-induced dissemination of both deletional (PAO1 and PAK) and insertional (PA14) mutants in four genes in the P. aeruginosa T3SS, exoS or exoU, exoT, and popB. There were no significant differences in GI colonization among these mutant strains and their WT counterparts, whereas rates of survival following dissemination were significantly decreased in mice infected by the T3SS mutant strains. However, there was a variable, strain-dependent effect on overall survival between parental and T3SS mutants. Thus, increased transcription of genes during in vivo murine GI colonization is not predictive of an essential role for the gene product in either colonization or overall survival following induction of neutropenia

    Structural Basis for Type VI Secretion Effector Recognition by a Cognate Immunity Protein

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    The type VI secretion system (T6SS) has emerged as an important mediator of interbacterial interactions. A T6SS from Pseudomonas aeruginosa targets at least three effector proteins, type VI secretion exported 1–3 (Tse1–3), to recipient Gram-negative cells. The Tse2 protein is a cytoplasmic effector that acts as a potent inhibitor of target cell proliferation, thus providing a pronounced fitness advantage for P. aeruginosa donor cells. P. aeruginosa utilizes a dedicated immunity protein, type VI secretion immunity 2 (Tsi2), to protect against endogenous and intercellularly-transferred Tse2. Here we show that Tse2 delivered by the T6SS efficiently induces quiescence, not death, within recipient cells. We demonstrate that despite direct interaction of Tsi2 and Tse2 in the cytoplasm, Tsi2 is dispensable for targeting the toxin to the secretory apparatus. To gain insights into the molecular basis of Tse2 immunity, we solved the 1.00 Å X-ray crystal structure of Tsi2. The structure shows that Tsi2 assembles as a dimer that does not resemble previously characterized immunity or antitoxin proteins. A genetic screen for Tsi2 mutants deficient in Tse2 interaction revealed an acidic patch distal to the Tsi2 homodimer interface that mediates toxin interaction and immunity. Consistent with this finding, we observed that destabilization of the Tsi2 dimer does not impact Tse2 interaction. The molecular insights into Tsi2 structure and function garnered from this study shed light on the mechanisms of T6 effector secretion, and indicate that the Tse2–Tsi2 effector–immunity pair has features distinguishing it from previously characterized toxin–immunity and toxin–antitoxin systems
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