652 research outputs found

    Evolution of the DAZ gene and the AZFc region on primate Y chromosomes

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    <p>Abstract</p> <p>Background</p> <p>The <it>Azoospermia Factor c </it>(<it>AZFc</it>) region of the human Y chromosome is a unique product of segmental duplication. It consists almost entirely of very long amplicons, represented by different colors, and is frequently deleted in subfertile men. Most of the <it>AZFc </it>amplicons have high sequence similarity with autosomal segments, indicating recent duplication and transposition to the Y chromosome. The <it>Deleted in Azoospermia </it>(<it>DAZ</it>) gene within the red-amplicon arose from an ancestral autosomal <it>DAZ-like </it>(<it>DAZL</it>) gene. It varies significantly between different men regarding to its copy number and the numbers of RNA recognition motif and DAZ repeat it encodes. We used Southern analyses to study the evolution of <it>DAZ </it>and <it>AZFc </it>amplicons on the Y chromosomes of primates.</p> <p>Results</p> <p>The Old World monkey rhesus macaque has only one <it>DAZ </it>gene. In contrast, the great apes have multiple copies of <it>DAZ</it>, ranging from 2 copies in bonobos and gorillas to at least 6 copies in orangutans, and these <it>DAZ </it>genes have polymorphic structures similar to those of their human counterparts. Sequences homologous to the various <it>AZFc </it>amplicons are present on the Y chromosomes of some but not all primates, indicating that they arrived on the Y chromosome at different times during primate evolution.</p> <p>Conclusion</p> <p>The duplication and transposition of <it>AZFc </it>amplicons to the human Y chromosome occurred in three waves, i.e., after the branching of the New World monkey, the gorilla, and the chimpanzee/bonobo lineages, respectively. The red-amplicon, one of the first to arrive on the Y chromosome, amplified by inverted duplication followed by direct duplication after the separation of the Old World monkey and the great ape lineages. Subsequent duplication/deletion in the various lineages gave rise to a spectrum of <it>DAZ </it>gene structure and copy number found in today's great apes.</p

    Real-Time, Non-Intrusive Detection of Liquid Nitrogen in Liquid Oxygen at High Pressure and High Flow

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    An integrated fiber-optic Raman sensor has been designed for real-time, nonintrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressures and high flow rates in order to monitor the quality of LOX used during rocket engine ground testing. The integrated sensor employs a high-power (3-W) Melles Griot diode-pumped, solid-state (DPSS), frequency-doubled Nd:YAG 532- nm laser; a modified Raman probe that has built-in Raman signal filter optics; two high-resolution spectrometers; and photomultiplier tubes (PMTs) with selected bandpass filters to collect both N2 and O2 Raman signals. The PMT detection units are interfaced with National Instruments Lab- VIEW for fast data acquisition. Studies of sensor performance with different detection systems (i.e., spectrometer and PMT) were carried out. The concentration ratio of N2 and O2 can be inferred by comparing the intensities of the N2 and O2 Raman signals. The final system was fabricated to measure N2 and O2 gas mixtures as well as mixtures of liquid N2 and LO

    Fiber Optic Raman Sensor to Monitor Concentration Ratio of Nitrogen and Oxygen in a Cryogenic Mixture

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    A spontaneous Raman scattering optical fiber sensor is developed for a specific need of NASA/SSC for long-term detection and monitoring of the quality of liquid oxygen (LOX) in the delivery line during ground testing of rocket engines. The sensor performance was tested in the laboratory and with different excitation light sources. To evaluate the sensor performance with different excitation light sources for the LOX quality application, we have used the various mixtures of liquid oxygen and liquid nitrogen as samples. The study of the sensor performance shows that this sensor offers a great deal of flexibility and provides a cost effective solution for the application. However, an improved system response time is needed for the real-time, quantitative monitoring of the quality of cryogenic fluids in harsh environment

    Environmental literacy on ecotourism: a study on student knowledge, attitude, and behavioral intentions in China and Taiwan

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    This study aims to gain further insights to Chinese and Taiwanese university students’ environmental literacy on ecotourism. A structural equation model is developed and validated in an effort to explore the differences between Chinese and Taiwanese university students in terms of their environmental knowledge, environmental attitude, and behavioral intentions. The results showed that the ecotourism perception of Chinese and Taiwanese university students affect their behavioral intentions. Chinese university students exhibited a higher correlation between ecotourism knowledge and behavioral intentions than their Taiwanese counterparts. The findings also revealed differences between the Chinese and Taiwanese students in their perception of ecotourism, and this disparity was particularly evident with regards to how ecotourism should be governed. A moderate difference in ecotourism behavioral intentions was also identified, in which Taiwanese university students were less likely to engage in self-empowerment or private empowerment, to be more educated in the field of ecotourism than their Chinese counterparts

    Feasibility of Bispectral Index-Guided Propofol Infusion for Flexible Bronchoscopy Sedation: A Randomized Controlled Trial

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    There are safety issues associated with propofol use for flexible bronchoscopy (FB). The bispectral index (BIS) correlates well with the level of consciousness. The aim of this study was to show that BIS-guided propofol infusion is safe and may provide better sedation, benefiting the patients and bronchoscopists.After administering alfentanil bolus, 500 patients were randomized to either propofol infusion titrated to a BIS level of 65-75 (study group) or incremental midazolam bolus based on clinical judgment to achieve moderate sedation. The primary endpoint was safety, while the secondary endpoints were recovery time, patient tolerance, and cooperation.The proportion of patients with hypoxemia or hypotensive events were not different in the 2 groups (study vs. control groups: 39.9% vs. 35.7%, p = 0.340; 7.4% vs. 4.4%, p = 0.159, respectively). The mean lowest blood pressure was lower in the study group. Logistic regression revealed male gender, higher American Society of Anesthesiologists physical status, and electrocautery were associated with hypoxemia, whereas lower propofol dose for induction was associated with hypotension in the study group. The study group had better global tolerance (p<0.001), less procedural interference by movement or cough (13.6% vs. 36.1%, p<0.001; 30.0% vs. 44.2%, p = 0.001, respectively), and shorter time to orientation and ambulation (11.7±10.2 min vs. 29.7±26.8 min, p<0.001; 30.0±18.2 min vs. 55.7±40.6 min, p<0.001, respectively) compared to the control group.BIS-guided propofol infusion combined with alfentanil for FB sedation provides excellent patient tolerance, with fast recovery and less procedure interference.ClinicalTrials. gov NCT00789815

    In-Place FPGA Retiming for Mitigation of Variational Single-Event Transient Faults

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    Osteoporosis Recovery by Antrodia camphorata

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    Antrodia camphorata has previously demonstrated the efficacy in treating cancer and anti-inflammation. In this study, we are the first to evaluate Antrodia camphorata alcohol extract (ACAE) for osteoporosis recovery in vitro with preosteoblast cells (MC3T3-E1) and in vivo with an osteoporosis mouse model established in our previous studies, ovariectomized senescence accelerated mice (OVX-SAMP8). Our results demonstrated that ACAE treatment was slightly cytotoxic to preosteoblast at 25 μg/mL, by which the osteogenic gene expression (RUNX2, OPN, and OCN) was significantly upregulated with an increased ratio of OPG to RANKL, indicating maintenance of the bone matrix through inhibition of osteoclastic pathway. Additionally, evaluation by Alizarin Red S staining showed increased mineralization in ACAE-treated preosteoblasts. For in vivo study, our results indicated that ACAE inhibits bone loss and significantly increases percentage bone volume, trabecular bone number, and bone mineral density in OVX-SAMP8 mice treated with ACAE. Collectively, in vitro and in vivo results showed that ACAE could promote osteogenesis and prevent bone loss and should be considered an evidence-based complementary and alternative medicine for osteoporosis therapy through the maintenance of bone health
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