92 research outputs found
Semen analysis of G olden R etriever healthy dogs and those affected by muscular dystrophy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106077/1/and12079.pd
Evaluation of lasting effects of heat stress on sperm profile and oxidative status of ram semen and epididymal sperm
Higher temperatures lead to an increase of testicular metabolism that results in spermatic damage. Oxidative stress is the main factor responsible for testicular damage caused by heat stress. The aim of this study was to evaluate lasting effects of heat stress on ejaculated sperm and immediate or long-term effects of heat stress on epididymal sperm. We observed decrease in motility and mass motility of ejaculated sperm, as well as an increase in the percentages of sperm showing major and minor defects, damaged plasma and acrosome membranes, and a decrease in the percentage of sperm with high mitochondrial membrane potential in the treated group until one spermatic cycle. An increased enzymatic activity of glutathione peroxidase and an increase of stressed cells were observed in ejaculated sperm of the treated group. A decrease in the percentage of epididymal sperm with high mitochondrial membrane potential was observed in the treated group. However, when comparing immediate and long-term effects, we observed an increase in the percentage of sperm with low mitochondrial membrane potential. In conclusion, testicular heat stress induced oxidative stress that led to rescuable alterations after one spermatic cycle in ejaculated sperm and also after 30 days in epididymal sperm
Population synthesis of millisecond and submillisecond pulsars
Known millisecond pulsars have periods longer than 1.558 ms. Recycled in
binary systems, neutron stars can attain very short spin periods. In this paper
we investigate the expected properties of the millisecond pulsar distribution
by simulating synthetic populations under different assumptions for the neutron
star equation of state and decay of the magnetic field. We find evidence that a
tail in the distribution of millisecond pulsars may exist at periods shorter
than those observed.Comment: 16 pages, LaTex + 2 .eps figures To Appear in The Astrophysical
Journal Letter
Sperm cryodamage occurs after rapid freezing phase: flow cytometry approach and antioxidant enzymes activity at different stages of cryopreservation
Abstract\ud
\ud
Background\ud
In order to improve the efficiency of bovine sperm cryopreservation process, it is important to understand how spermatozoa respond to differences in temperature as well as the ability to recover its own metabolism. The combination between flow cytometry approach and antioxidant enzymes activity allows a more sensible evaluation of sperm cell during cryopreservation. The aim of this study was to evaluate sperm attributes and antioxidant enzymes activity during different stages of cryopreservation process. Semen samples from Holstein bulls (n = 4) were separated in 3 treatments: fresh (37 °C); cooled (5 °C); and thawed. Evaluation occurred at 0 h and 2 h after incubation. Membrane integrity, mitochondrial membrane potential (MMP) and DNA damages were evaluated by flow cytometry; activities of antioxidant enzymes such as catalase, superoxide dismutase and gluthatione peroxidase were measured by spectrofotometry.\ud
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Results\ud
There was an increase in the percentage of sperm with DNA damage in the thawed group, compared to fresh and cooled, and for 2 hs of incubation when compared to 0 h. Considering MMP, there was an increase in the percentage of cells with medium potential in thawed group when compared to fresh and cooled groups. Opposingly, a decrease was observed in the thawed group considering high mitochondrial potential. Also in the thawed group, there was an increase on cells with damaged acrosome and membrane when compared to fresh and cooled groups. Significant correlations were found between antioxidant enzymes activity and membrane or mitochondrial parameters.\ud
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Conclusion\ud
Based on our results, we conclude that cryopreservation affects cellular and DNA integrity and that the critical moment is when sperm cells are exposed to freezing temperature. Also, our study indicates that intracellular antioxidant machinery (SOD and GPX enzymes) is not enough to control cryodamage.This study was supported by São Paulo Research Foundation (FAPESP),\ud
process number 2010/18978-9 and 2007/58487-1
Where May Ultra-Fast Rotating Neutron Stars Be Hidden?
The existence of ultra-fast rotating neutron stars (spin period P < 1 ms) is
expected on the basis of current models for the secular evolution of
interacting binaries, though they have not been detected yet. Their formation
depends on the quantity of matter accreted by the neutron star which, in turn,
is limited by the mechanism of mass ejection from the binary. An efficient mass
ejection can avoid the formation of ultra-fast pulsars or their accretion
induced collapse to a black hole. We propose that significant reductions of the
mass-transfer rate may cause the switch-on of a radio pulsar phase, whose
radiation pressure may be capable of ejecting out of the system most of the
matter transferred by the companion. This can prevent, for long orbital periods
and if a sufficiently fast spin has been reached, any further accretion, even
if the original transfer rate is restored, thus limiting the minimum spin
period attainable by the neutron star. We show that close systems (orbital
periods P_orb \sim 1 hr are the only possible hosts for ultra-fast spinning
neutron stars. This could explain why ultra-fast radio pulsars have not been
detected so far, as the detection of pulsars with very short spin periods in
close systems is hampered, in current radio surveys, by strong Doppler
modulation and computational limitations.Comment: 6 pages, including 1 figure. To appear in ApJ
Radio Pulsars in the Magellanic Clouds
We report the results of a survey of the Small Magellanic Cloud (SMC) for
radio pulsars conducted with the 20-cm multibeam receiver of the Parkes
64-meter telescope. This survey targeted a more complete region of the SMC than
a previous pulsar search and had an improvement in sensitivity by a factor of
about two for most pulsar periods. This survey is much more sensitive to fast
young pulsars (with P < 100 ms) and is the first survey of the SMC with any
sensitivity to millisecond pulsars. Two new pulsars were discovered in the
survey, one of which is located within the SMC. The number of pulsars found in
the survey is consistent with the expected number derived using several
methods. We also report the serendipitous discovery of a new pulsar in the 30
Doradus region of the Large Magellanic Cloud (LMC). These discoveries bring the
total number of rotation-powered pulsars currently known in the Magellanic
Clouds to eight. We have also made refined timing measurements for the new
discoveries as well as for three previously known LMC pulsars. The age
distribution of luminous Magellanic Cloud pulsars supports the conjecture that
pulsars younger than about 5 Myr are more luminous on average than older
pulsars.Comment: 14 pages, including 6 figures and 3 tables. Accepted for publication
in Ap
Deontological issues - possible misdiagnosis of cerebral metastases
Authors analyses a number of 4588 (52, 24% over 50 years old) patients operated for cerebral tumors in the Clinic Emergency Hospital “Bagdasar-Arseni” from Bucharest, between 2000-2010, with peculiar attention to the concordance between the preoperative and postoperative diagnosis, related to the actual policy to evaluate a neurosurgical patient before surgery. 903 cases were cerebral metastases and 69,5% aged over 50 years old. In 9,7% of cases we recorded a preoperative misdiagnosis of a metastasis due to few main reasons: unavailable information about a present primitive cancer, treacherous MRI image with a single confusing appearance of a cerebral lesion, age less than 50 years old, clinical presentation and biological evaluation inconsistent with malignancy. Authors point that these situations can have serious consequences related to professional competence, deterioration of the patient-doctor relationship, increasing costs for completion of diagnosis and treatment, and inadequate information about patient’s prognosis
In vitro oocyte transport through the oviduct of buffalo and crossbred beef cows
The present study was conducted to verify if the elevation of plasma concentrations of estradiol during superovulatory treatments affects the oocyte transport in buffalo females, as well as if the inferior quality of buffalo oocytes and/or some functional difference on the oviduct of these animals is responsible for the low embryo recovery rate in superovulated uffaloes when compared to cows subjected to the same treatment. Oviducts of 10 buffaloes and 15 of cows, treated to induce a single ovulation were used. The oviducts were placed on Petri dishes and received the following treatments: 5 buffalo oocytes with no E2 (G-BufBuf and G-BovBuf), 5 bovine oocytes with no E2 (G-BufBov and G-BovBov), 5 buffalo oocytes with E2 (G-BufE2Buf and G-BovE2Buf) and 5 bovine oocytes with E2 (G-BufE2Bov and G-BovE2Bov; factorial 2x2x2). Oocytes were incubated for 24h. Subsequently, oviducts were washed and oocytes were recovered and counted. Since no interactions were found between E2 treatment, oviducts and oocytes species, main effects were analyzed separately. Recovery rate and number of oocytes was higher on cattle compared to buffaloes (35.0+8.6% and 1.4+0.3 vs. 10.0±4.6% and 0.5±0.2, respectively; p<0.05); no effect of E2 treatment was observed on recovery rate and number of oocytes (29.8±9.0% and 1.3±0.4 vs. 16.9±6.1% and 0.7±0.2, respectively; p>0.05); the number of buffaloes and bovine oocytes recovered were similar (1.4±0.4 and 0.6±0.2, respectively; p>0.05). Oocytes recovery rate showed a trend (P=0.07) to be higher when buffalo oocytes were implanted when compared to bovine oocytes (35.2±9.2% vs. 12.9±5.4%). Present results suggest that oocyte transport by the oviduct of buffaloes and bovine was not dependent on oocytes species or E2 supplementation to the culture medium.O presente estudo foi realizado para verificar se a elevação das concentrações plasmáticas de estradiol durante os tratamentos superovulatórios afeta o transporte dos oócitos em fêmeas bubalinas, bem como se a qualidade inferior dos oócitos de búfalos e/ou alguma diferença funcional no oviduto destes animais é responsável pela baixa taxa de recuperação de embriões em búfalas superovuladas quando comparadas a vacas submetidas ao mesmo tratamento. Foram utilizados 10 ovidutos de búfalas e 15 de vacas, tratadas para a indução de ovulação única. Os ovidutos foram colocados em placas de Petri e receberam os seguintes tratamentos: sem E2 e inseridos com 5 oócitos de búfalas (G-BufBuf e G-BovBuf); sem E2 e com 5 oócitos de vacas (G-BufBov e G-BovBov); com E2 e com 5 oócitos de búfalas (G-BufE2Buf e G-BovE2Buf); e com E2 e com 5 oócitos de vacas (G-BufE2Bov e G-BovE2Bov; fatorial 2x2x2). Posteriormente, foram incubados por 24h e, após esse período, foram lavados para a recuperação e contagem dos oócitos. Como não foi verificado efeito de interação, foram analisados os efeitos principais. O número e a taxa de recuperação de oócitos foi maior em ovidutos de vacas que de búfalas (1,4±0,3/35,0±8,6% vs. 0,5±0,2/10,0±4,6%; P<0,05). Foi verificado que o tratamento com ou sem E2 não interferiu no número e na taxa de recuperação de oócitos (1,3±0,4/29,8±9,0% vs. 0,7±0,2/16,9±6,1%; P>0,05). Não foi verificada diferença no número de oócitos de búfalas ou de vacas recuperados (1,4±0,4 e 0,6±0,2; P>0,05). Observou-se também que houve tendência (P=0,07) de maior taxa de recuperação de oócitos de búfalas que de vacas (35,2±9,2% vs. 12,9±5,4%). Os dados são indicativos de que o transporte de oócitos pelo oviduto de búfalas e de vacas independe da espécie do oócito e não é influenciado pelo E2
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