Linda H Crane

Differentiation-dependent expression of gelatinase B/matrix metalloproteinase-9 in trophoblast cells

Abstract The purpose of this study was to evaluate the Rcho-1 trophoblast culture system as a model for studying trophoblast invasion and to examine stage-specific expression of enzyme(s) potentially participating in rat trophoblast giant cell invasive behavior. The invasive behavior of the differentiating Rcho-1 trophoblast cells was demonstrated using Matrigel invasion chambers. Gelatin zymography and Western blot analysis of conditioned medium from differentiating Rcho-1 trophoblast cell cultures and rat ectoplacental cone outgrowths revealed a differentiation-dependent increase in gelatinase B/matrix metalloproteinase (MMP-9). Nothern blot and reverse transcriptase polymerase chain reaction (RT-PCR) analyses of Rcho-1 trophoblast or ectoplacental cone cells also showed increasing expression of MMP-9 accompanying cell differentiation. Rcho-1 trophoblast cells stably transfected with MMP-9 promoter/luciferase reporter constructs exhibited a differentiation-dependent increase in MMP-9 promoter activation. In conclusion, trophoblast giant cell differentiation is characterized by transcriptional activation of the MMP-9 gene and appearance of the invasive phenotype.

Hormonal Variation of Rat Uterine Contractile Responsiveness to Selective Neurokinin Receptor Agonists

Abstract Regulated uterine contractions are important in many reproductive functions such as sperm transport and embryo positioning during implantation. The role of classical neurotransmitters including acetylcholine and norepinephrine in regulating myometrial contractility has been well studied; however, the peripheral role of sensory neurotransmitters such as the neurokinins is less clear. The major neurokinins are substance P, neurokinin A, and neurokinin B, which predominantly activate neurokinin receptors (NK-Rs) 1, 2, and 3, respectively. This study utilized selective receptor agonists to examine the role of NK-Rs in uterine contractility. Uterine tissues, obtained from the major stages of the rat estrous cycle, were stimulated with selective NK-R agonists. Addition of each agonist resulted in a significant contractile response. However, the magnitude and nature of the response were dependent upon the stage of the estrous cycle, with responses to all agonists being significantly decreased in tissue from proestrus and estrus. Furthermore, the nature of NK3-R-mediated contraction was different in tissue from proestrus and estrus compared to metestrus and diestrus. The hormonal dependence of NK-R-mediated contractility was then examined in the ovariectomized estrogen-supplemented rat model. These studies confirmed that the magnitude and nature of uterine contractility in response to NK-R activation depend upon the hormonal environment.

Estrogen-Dependent Regulation of Neurokinin 3 Receptor-Mediated Uterine Contractility in the Rat

Abstract The receptors for neurokinin 1 (NK1-R), neurokinin 2 (NK2-R), and neurokinin 3 (NK3-R) are expressed and functionally active in the uterus, promoting strong contractions of the myometrium. Previously, we demonstrated that myometrial contractility activated by the NK-Rs is regulated by estrogen. In the current study, we furthered our investigations of the role of estrogen in the regulation of NK3-R-mediated myometrial contractility. Estrogen promotes both heterologous and homologous desensitization of NK3-R-mediated uterine contractility. In tissue obtained from estrogen-dominated rats (ovariectomized estrogen-treated rats and rats in estrus), the magnitude of uterine contractions decreased in response to consecutive additions of the NK3-R-selective agonist senktide. By addition of the fourth dose of agonist, the contractile response was routinely barely above baseline. In contrast, in tissue obtained from non-estrogen-dominated rats consecutive doses of senktide resulted in contractions of identical magnitude. The homologous desensitization was specific to the NK3-R, and the desensitization of the NK3-R-mediated response did not affect the magnitude or nature of uterine contractions in response to NK1-R or NK2-R activation. Furthermore, heterologous and homologous desensitization of NK3-R-mediated contractility is dependent upon the duration of exposure to estrogen. This complex mechanism appears to be important in intact tissue; capsaicin-mediated release of endogenous neuropeptides resulted in a desensitization of response to subsequent stimulation with senktide in estrogen-dominated uterine tissue.

In vivo myometrial activity in the rat during the oestrous cycle: studies with a novel technique of video laparoscopy

Previous techniques of recording myometrial activity in vivo gave limited information about the nature of contractions, and disrupted normal reproductive events. To overcome these drawbacks we developed a new in vivo method of video laparoscopy (VL). This involves positioning a laparoscope in the abdomen of anaesthetized rats to view the caudal ends of both uterine horns. Myometrial activity is recorded by video camera onto video tape. Myometrial contractions are classified according to the muscle layers involved, the interaction between layers and the direction of propagation. Experiments with intrauterine balloons and electromyography (EMG) in conscious and ketamine/xylazine anaesthetized rats showed that this anaesthetic does not have major effects on myometrial activity. To validate the VL method, recordings were obtained throughout the oestrous cycle and compared with results obtained with EMG in conscious rats. The frequency and pattern of activity were similar with both techniques although more information was obtained from VL. Frequency of contractions was highest in oestrus and dioestrus and lowest in pro-oestrus, when contractions occurred in groups separated by quiescent intervals. At all stages, longitudinal contractions propagating towards the cervix predominated. Circular muscle activity was only seen at oestrus and dioestrus; that at oestrus consisted of weak peristalses, that at dioestrus was more complex. A major advantage of VL is that it does not interfere with the course of the oestrous cycle, pseudopregnancy or early pregnancy.

Postcopulatory myométrial activity in the rat as seen by video-laparoscopy

Myometrial activity was analysed by video-laparoscopy in unmated and mated oestrous female rats. In the former, most contractions propagated caudally and were predominantly longitudinal, with circular contractions limited to weak peristalsis. Mating had dramatic effects on activity, inducing a high frequency of strong peristaltic and non-peristaltic circular contractions propagating both cranially and caudally. Activity remained elevated for up to 10 h, decreasing to control levels as uterine contents were lost when the vaginal plug disintegrated. Mechanical stimulation of the cervix, sufficient to induce pseudopregnancy, increased the frequency of weak peristalsis but did not induce myometrial activity comparable to that seen after mating. Treatment of mated females with indomethacin returned myometrial activity towards control levels, suggesting that myometrial stimulation involved prostanoid production. After mating to intact males the uterus took on a characteristic blue colour suggestive of hypoxia. This too was abolished by indomethacin treatment. Removal of accessory reproductive glands from males showed that induction of myometrial activity and the colour change both required constituents from the vas deferens, seminal vesicles and coagulating glands. Males lacking seminal vesicles or coagulating glands were infertile. The prolonged myometrial activity and putative hypoxia induced by seminal constituents may be important in survival and selection of sperm.

Discrepant stakeholder perspectives on graduate employability strategies

ABSTRACT A literature review identified 12 strategies that have been empirically linked to improvements in graduate employability. A survey methodology was used to investigate self-reported use and/or perspectives on these strategies among four stakeholder groups. The following questions were asked: to students – What strategies are you using to improve your graduate employability; to graduates – What strategies did you use to improve your employability?; to higher education career development professionals and educators – Which of the following employability strategies do you provide for students?; and to employers – Which of the following strategies undertaken by students does your organisation value when recruiting graduates? Across the four stakeholder groups, 705 responses were received and analysed. The key findings were discrepancies between the strategies reported in the literature and those indicated in the surveys, as well as discrepancies between stakeholder groups in regard to which strategies were indicated.

Twelve tips for increasing the defensibility of assessment decisions

Abstract In an era of increasing scrutiny of the performance of graduates in the workplace, there can be frustrations when decisions about learners with borderline or poor performance in formal assessments are over-turned in appeal processes. This article addresses the approach to reducing the uncertainty about assessment decisions and surviving appeals.

Pace-maker activity in the myometrium of the oestrous rat : in vivo studies using video-laparoscopy

Female rats had one oviduct, or the cranial tip of one or both uterine horns, lesioned by coagulation, or separated from the remainder of the uterus. After recovery and return to oestrous cycles, myometrial activity at oestrus was analysed by video-laparoscopy. Lesioning the oviduct had no effect on myometrial activity. Coagulating the cranial tip of one horn initially reduced the frequency of ipsilateral longitudinal contractions propagating caudally, but this returned to normal after 14 days. Separating the cranial tip of the uterus had permanent effects on myometrial activity. Separation of one tip reduced the frequency of ipsilateral longitudinal contractions propagating caudally, had no effect on ipsilateral contractions propagating cranially, but reduced the frequency of contralateral contractions propagating cranially. The effect of a lesion near one uterotubal junction on contractions originating contralaterally near the cervix results from communication between uterine horns at the cervical junction; arrival of a caudally propagating contraction in one horn frequently generates a cranially propagating contraction in the other. Separating both uterine tips reduced the frequency of longitudinal contractions propagating in both directions. We conclude that, at oestrus, most spontaneous myometrial contractions are generated by pace-makers in the cranial tip of each uterine horn. The pace-makers are close to the uterotubal junction and regenerate after destruction by coagulation. When their influence is permanently removed, new pace-makers do not develop in myometrium caudal to the lesion. We conclude that most myometrial cells do not exhibit spontaneous pace-maker activity in vivo.

Training and Support of Sessional Staff to Improve Quality of Teaching and Learning at Universities

Sessional staff is increasingly involved in teaching at universities, playing a pivotal role in bridging the gap between theory and practice for students, especially in the health professions, including pharmacy. Although sessional staff numbers have increased substantially in recent years, limited attention has been paid to the quality of teaching and learning provided by this group. This review will discuss the training and support of sessional staff, with a focus on Australian universities, including the reasons for and potential benefits of training, and structure and content of training programs. Although sessional staff views these programs as valuable, there is a lack of in-depth evaluations of the outcomes of the programs for sessional staff, students and the university. Quality assurance of such programs is only guaranteed, however, if these evaluations extend to the impact of this training and support on student learning.

Circular versus longitudinal myometrial contractile response to selective tachykinin receptor agonists in rat

This study compared the nature and magnitude of the contractile response produced in vitro by selective NK1, NK2 and NK3 tachykinin receptor agonists in circularly and longitudinally oriented strips of myometrium from ovariectomised and ovariectomised oestrogen-treated rats. The nature of the responses produced upon stimulation of the tachykinin receptors varied between the different myometrial preparations and the hormonal environment from which the tissue was taken. Variations included: (i) sustained contraction until washout of agonist; (ii) biphasic contraction until washout of agonist; and (iii) monophasic contraction. The major differences in magnitude of contractions were seen in preparations from oestrogen-treated animals in which responses to stimulation of all tachykinin receptors were reduced in comparison to preparations from non-oestrogen treated animals. Furthermore, the responses in circularly oriented myometrium preparations from oestrogen-treated animals were all markedly reduced compared to responses in longitudinally oriented myometrium preparations. These results suggest that the tachykinin receptors in longitudinally and circularly oriented myometrial layers are differentially regulated, especially in tissue isolated from an oestrogen-dominated environment.