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51.
A first step to elucidating the roles that steroids may play in the processes of ovarian development and early follicular growth is to identify the cell types that are likely to be receptive to steroids. Thus, cell types expressing receptors for oestrogen (alpha and beta form; ERalpha and ERbeta respectively), androgen (AR) and progesterone (PR) were determined by in situ hybridisation and immunohistochemistry in ovine ovarian tissues collected during ovarian development and follicular formation (days 26-75 of fetal life) as well as during the early stages of follicular growth. Expression of ERbeta was observed early during ovarian development and continued to be expressed throughout follicular formation and also during the early stages of follicular growth. ERbeta was identified in germ cells as well as in the granulosa cells. At the large preantral stage of follicular growth, expression of ERalpha was also consistently observed in granulosa cells. AR was first consistently observed at day 55 of fetal life in stroma cells throughout the ovary. Within the follicle, expression was observed in granulosa and thecal cells from the type-2 to -3 stage of follicular growth. PR mRNA did not appear to be expressed during ovarian development (days 26-75 of gestation). However, PR (mRNA and protein) was observed in the theca of type-3 (small preantral) and larger follicles, with mRNA -- but not protein -- observed in granulosa cells of some type-4 and 5 follicles. Expression of ERbeta, ERalpha and AR, as well as PR, was also observed in the surface epithelium and ovarian stroma of the fetal, neonatal and adult ovary. Thus, in sheep, steroid hormones have the potential to regulate the function of a number of different ovarian cell types during development, follicular formation and early follicular growth. 相似文献
52.
Rock Adrienne M. L.; Trainor Laurel J.; Addison Tami L. 《Canadian Metallurgical Quarterly》1999,35(2):527
Mothers were recorded singing a song of their choice in both a lullaby style and a play-song style to their 6-month-olds. Adult raters identified the play-song-style and lullaby-style versions with 100% accuracy. Play-song-style renditions were rated as being more brilliant, clipped, and rhythmic and as having more smiling and more prominent consonants. Lullaby-style renditions were characterized as being more airy, smooth, and soothing. Adults observed videotapes (without sound) of 6-month-olds listening to alternating lullaby-style and play-song-style trials and performed at above chance levels when determining which music the infants were hearing. Coding analyses revealed that infants focused their attention more toward themselves during lullaby-style trials and more toward the external world during play-song-style trials. These results suggest that singing may be used to regulate infants' states and to communicate emotional information. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
53.
Neil S. Grigg Marvin E. Criswell Darrell G. Fontane Laurel Saito Thomas J. Siller Daniel K. Sunada 《Canadian Metallurgical Quarterly》2004,130(3):160-165
An integrated curriculum, which draws material from different areas to teach students about design and problem-solving, offers civil engineering educators an option for accommodating new topics without increasing the number of courses. Freshman engineering and the senior capstone course are two examples of integrated courses, and the writers present a 5-year perspective on an approach that extends the concept of integration to six additional courses, comprised of an 8-course, integrated civil engineering core curriculum. Drawing on their combined experiences with the courses and assessment in a review by the Accreditation Board for Engineering and Technology, the writers conclude that the curriculum offers a useful vehicle by which to add material to the 4-year program without increasing the number of credit hours, and offers flexible courses to meet goals of professional groups. The paper describes lessons learned, challenges that remain, and current approaches to improvement. 相似文献
54.
Trehub Sandra E.; Unyk Anna M.; Kamenetsky Stuart B.; Hill David S.; Trainor Laurel J.; Henderson Joanna L.; Saraza Myra 《Canadian Metallurgical Quarterly》1997,33(3):500
Mothers and fathers sang a song of their choice, once to their infant and once as if to their infant (simulated). The pitch of songs was higher and the tempo slower for infant-directed than for simulated versions. Listeners varying in child-care experience, musical background, and cultural origin reliably identified which of the two versions was infant-directed (Experiment 1) . Identification accuracy was enhanced by musical training, knowledge of the singers' language and culture, and by greater pitch and tempo differences between versions. Other adult listeners who rated the singer's emotional engagement assigned significantly higher ratings to infant-directed than to simulated versions (Experiment 2). Differences in pitch and tempo between both versions predicted emotional engagement ratings. Finally, rating differences between infant-directed and simulated versions were highly correlated with identification accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
55.
MT Brandt SP Levine DG Smith HJ Ettinger BF Gallimore 《Canadian Metallurgical Quarterly》1998,59(5):335-345
The ability of IL-12 and IL-15 to enhance natural killer (NK) activity and antibody-dependent cellular cytotoxicity (ADCC) of mononuclear cells (MNCs) from HIV+ children and their mothers was investigated. MNCs from HIV+ patients were deficient in NK and ADCC activity compared to control MNCs against several target cells. Overnight incubation with IL-15 or IL-12 augmented NK activity of MNCs from both patients and controls, and the combination of IL-12 and IL-15 resulted in the greatest enhancement. ADCC in HIV+ patients against gp120-coated CEM.NKR cells or chicken erythrocytes could also be enhanced by IL-2 or IL-15 in overnight cultures. Culturing MNCs with either IL-2 or IL-15 for 1 week increased the NK activity in patients to levels of controls treated with these cytokines. However, the response to the combination of IL-12 and IL-15 was less than that to IL-15 alone in 1-week cultures. Culturing MNCs with IL-2 and IL-15 for 1 week also increased the percentage of CD16+/CD56+ cells in both patients and controls. Thus, IL-15 can restore the deficient NK activity in patients and may be a candidate for immunomodulative therapy in HIV+ patients. 相似文献
56.
A computational technique is described for calculation of the interspike interval and poststimulus time histograms for the responses of an integrate-and-fire model to arbitrary inputs. The effects of the model parameters on the response statistics were studied systematically. Specifically, the probability distribution of the membrane potential was calculated as a function of time, and the mean interspike interval and PST histogram were calculated for arbitrary inputs. For stationary inputs, the regularity of the output was studied in detail for various model parameters. For nonstationary inputs, the effects of the model parameters on the output synchronization index were explored. The results show that enhanced synchronization in response to low-frequency stimuli required a large number (n > 25) of weak inputs. Irregular responses and a linear input-output rate relationship required strong (but subthreshold) inputs with a small time constant. A model cell with mixed-amplitude synaptic inputs can respond to stationary inputs irregularly and have enhanced synchronization to nonstationary inputs that are phase-locked to low-frequency inputs. Both of these response properties have been reported for some cells in the ventral cochlear nucleus in the auditory brainstem. 相似文献
57.
Factors governing the direct gate current in silicon field-effect transistors are reviewed, and a mode of operation which results in zero d.c. gate leakage is described. This leads to the postulation of a new d.c. equivalent circuit for the field-effect-transistor gate. 相似文献
58.
A balanced system of minority-carrier-storage diodes, energised from avalanche-pulse generators, is described, which delivers fast-rise/fast-fall pulses of adjustable length. Nanosecond risetime is obtained with step-recovery diodes; readily available charge-storage coupling diodes may be used to achieve 5 ns rise and fall times and amplitudes of some tens of volts into 50 ?. 相似文献
59.
60.
Juengel JL Quirke LD Lun S Heath DA Johnstone PD McNatty KP 《Reproduction (Cambridge, England)》2011,142(4):565-572
Sheep with a heterozygous inactivating mutation in the bone morphogenetic protein 15 (BMP15) gene experience an increased ovulation rate during either a natural oestrous cycle or a cycle in which exogenous FSH and eCG (gonadotrophins) are given to induce multiple ovulations. The primary aim of these studies was to determine whether ewes immunised against BMP15 would also show an improved superovulation rate following exogenous gonadotrophin treatment. A secondary aim was to determine the effects of BMP15 immunisation on ovarian follicular characteristics. In most ewes (i.e. > 75%) immunised with a BMP15-keyhole limpet haemocyanin peptide in an oil-based adjuvant in order to completely neutralise BMP15 bioactivity, there was no superovulation response to exogenous gonadotrophins. In ewes treated with exogenous gonadotrophins following a BMP15-BSA peptide immunisation in a water-based adjuvant to partially neutralise BMP15 bioactivity, the ovulation rate response was similar to the control superovulation treatment groups. Characterisation of follicular function revealed that the water-based BMP15-immunised animals had fewer non-atretic follicles 2.5-3.5 or > 4.5 mm in diameter compared with controls. Basal concentrations of cAMP were higher in granulosa cells from animals immunised against BMP15 than control animals. There were no significant differences in the concentrations of cAMP between granulosa cells from BMP15- and control-immunised animals when given FSH or hCG, although there were differences in the proportions of follicles in different size classes that responded to FSH or hCG. Thus, immunisation against BMP15 may have been causing premature luteinisation and thereby limiting the numbers of follicles recruited for ovulation following treatment with exogenous gonadotrophins. 相似文献