Nitric oxide control of lower vertebrate blood vessels by vasomotor nerves

In mammals, much is understood about the endothelial and neural NO control mechanisms in the vasculature. In contrast, NO control of blood vessels in lower vertebrates is poorly understood, with the majority of research focusing on the presence of an endothelial NO system; however, its presence remains controversial. This study examined the mechanisms by which NO regulates the large blood vessels of non-mammalian vertebrates. In all species examined, the arteries and veins contained a plexus of NOS-positive perivascular nerves that included nerve bundles and fine, varicose nerve terminals. However, in the large arteries and veins of various species of fishes and amphibians, no anatomical evidence was found for endothelial NOS using both NADPH-diaphorase and eNOS immunohistochemistry. In contrast, perinuclear NOS staining was readily apparent in blue-tongue lizard, pigeon and rat, which suggested that eNOS first appeared in reptiles. Physiological analysis of NO signalling in the vascular smooth muscle of short-finned eel and cane toad could not find any evidence for endothelial NO signalling. In contrast, it appears that activation of the nitrergic vasomotor nerves is responsible for NO control of the blood vessels.

Natriuretic peptide guanylyl cyclase receptors in the kidney of the Japanese eel, Anguilla japonica

Natriuretic peptides are linked to osmoregulation, cardiovascular and volume regulation in fishes. The peptides bind to two guanylyl-cyclase-linked receptors, natriuretic peptide receptor-A (NPR-A) and NPR-B, to elicit their effects. Atrial natriuretic peptide (ANP) binds principally to NPR-A, whereas C-type natriuretic peptide (CNP) binds to NPR-B. The teleost kidney has an important role in the maintenance of fluid and electrolyte balance; therefore, the location of NPR-A and NPR-B in the kidney could provide insights into the functions of natriuretic peptides. This study used homologous, affinity purified, polyclonal antibodies to NPR-A and NPR-B to determine their location in the kidney of the Japanese eel, Anguilla japonica. Kidneys from freshwater and seawater acclimated animals were fixed overnight in 4% paraformaldehyde before being paraffin-embedded and immunostained. NPR-A immunoreactivity was found on the apical membrane of proximal tubule 1 and the vascular endothelium including the glomerular capillaries. In contrast, NPR-B immunoreactivity was located on the smooth muscle of blood vessels including the glomerular afferent and efferent arterioles, and on smooth muscle tissue surrounding the collecting ducts. No difference in the distribution of NPR-A and NPR-B was observed between freshwater and seawater kidneys. Immunoreactivity was not observed in any tissue in which the antibodies had been preabsorbed. In addition, there was no difference in NPR-A and NPR-B mRNA expression between freshwater-acclimated and seawater-acclimated eels. These results suggest that, although utilizing the same second messenger system, ANP and CNP act on different targets within the kidney and presumably elicit different effects.

Myoepithelial molecular markers in human breast carcinoma PMC42-LA cells are induced by extracellular matrix and stromal cells

The microenvironment plays a key role in the cellular differentiation of the two main cell lineages of the human breast, luminal epithelial, and myoepithelial. It is not clear, however, how the components of the microenvironment control the development of these cell lineages. To investigate how lineage development is regulated by 3-D culture and microenvironment components, we used the PMC42-LA human breast carcinoma cell line, which possesses stem cell characteristics. When cultured on a two-dimensional glass substrate, PMC42-LA cells formed a monolayer and expressed predominantly luminal epithelial markers, including cytokeratins 8, 18, and 19; E-cadherin; and sialomucin. The key myoepithelial-specific proteins alpha-smooth muscle actin and cytokeratin 14 were not expressed. When cultured within Engelbreth-Holm- Swarm sarcoma-derived basement membrane matrix (EHS matrix), PMC42-LA cells formed organoids in which the expression of luminal markers was reduced and the expression of other myoepithelial-specific markers (cytokeratin 17 and P-cadherin) was promoted. The presence of primary human mammary gland fibroblasts within the EHS matrix induced expression of the key myoepithelial-specific markers, alpha-smooth muscle actin and cytokeratin 14. Immortalized human skin fibroblasts were less effective in inducing expression of these key myoepithelial-specific markers. Confocal dual-labeling showed that individual cells expressed luminal or myoepithelial proteins, but not both. Conditioned medium from the mammary fibroblasts was equally effective in inducing myoepithelial marker expression. The results indicate that the myoepithelial lineage is promoted by the extracellular matrix, in conjunction with products secreted by breast-specific fibroblasts. Our results demonstrate a key role for the breast microenvironment in the regulation of breast lineage development.

Extremely high conservation in the untranslated Region as well as the coding region of CNP mRNAs throughout elasmobranch species

C-type natriuretic peptide (CNP) is a crucial osmoregulatory hormone in elasmobranchs, participating in salt secretion and drinking. In contrast to teleosts and tetrapods in which the NP family is composed of a group of structurally related peptides, we have shown that CNP is the sole NP in sharks. In the present study, CNP cDNAs were cloned from four species of batoids, another group of elasmobranchs. The cloned batoid CNP precursors contained a plausible mature peptide of 22 amino acid residues that is identical to most shark CNP-22s, but five successive amino acids were consistently deleted in the prosegment compared with shark precursors, supporting the diphyletic classification of sharks and rays. In addition, molecular phylogenetic trees of CNP precursors were consistent with a diphyletic interpretation. Except for the deletion, the nucleotide and deduced amino acid sequences of the CNP cDNAs are extremely well-conserved among all elasmobranch species, even between sharks and rays. Surprisingly, high conservation is evident not only for the coding region, but also for the untranslated regions. It is most likely that the high conservation is due to the low nucleotide substitution rate in the elasmobranch genome, and high selection pressure. The 3′-untranslated region of the elasmobranch CNP cDNAs contained three to six repeats of the ATTTA motif that is associated with the regulation of mRNA stability and translation efficiency. Alternative polyadenylation sites were also found; the long 3′-untranslated region contains a core of ATTTA motifs while the short form has only one or no ATTTA motif, indicating that the post-transcriptional modification of mRNA is important for regulation of CNP synthesis. These characteristics in the 3′-untranslated region were conserved among all elasmobranch CNP cDNAs. Since CNP has been implicated as a fast-acting hormone to facilitate salt secretion from the rectal gland, the conserved 3′-untranslated region most likely contributes to rapid regulation of CNP synthesis in elasmobranchs in response to acute changes in internal and external environments.

A perspective on the role of natriuretic peptides in amphibian osmoregulation

The natriuretic peptide (NP) system is a complex family of peptides and receptors that is primarily linked to the maintenance of osmotic and cardiovascular homeostasis. In amphibians, the potential role(s) of NPs is complicated by the range of osmoregulatory strategies found in amphibians, and the different tissues that participate in osmoregulation. Atrial NP, brain NP, and C-type NP have been isolated or cloned from a number of species, which has enabled physiological studies to be performed with homologous peptides. In addition, three types of NP receptors have been cloned and partially characterised. Natriuretic peptides are always potent vasodilators in amphibian blood vessels, and ANP has been shown to increase the permeability of the microcirculation. In the perfused kidney, ANP causes vasodilation, diuresis and natriuresis that are caused by an increased GFR rather than effects in the renal tubules. These data are supported by the presence of ANP receptors only on the glomeruli and renal blood vessels. In the bladder and skin, the function of NPs is enigmatic because physiological analysis of the effects of ANP on bladder and skin function has yielded conflicting data with no clear role for NPs being revealed. Overall, NPs often have no direct effect, but in some studies they have been shown to inhibit the function of AVT. In addition, there is evidence that ANP can inhibit salt retention in amphibians since it can inhibit the ability of adrenocorticotrophic hormone or angiotensin II to stimulate corticosteroid secretion. It is proposed that an important role for cardiac NPs could be in the control of hypervolaemia during periods of rapid rehydration, which occurs in terrestrial amphibians.

The response of the natriuretic peptide system to water deprivation in the desert rodent, Notomys alexis

Natriuretic peptides (NPs) are regulatory molecules that cause cGMP-mediated diuresis and natriuresis in mammals. Accordingly, it is interesting to consider their role in desert-adapted animals in which water is often limited. This study investigated the response of the natriuretic peptide (NP) system to varying periods of water deprivation (WD) in the Australian desert rodent species, Notomys alexis. It was hypothesised that the expression of the NP system will be down-regulated in water-deprived N. alexis compared to water-replete animals. The plasma levels of ANP were significantly reduced after 3 days of WD, but were unaffected by 7, 14 and 28 days of WD. Water deprivation for 3, 7, 14 days had a variable effect on the mRNA expression of ANP, CNP, NPR-A, NPR-B, and NPR-C, and a uniform down-regulation was not observed. However, after 28 days of WD, mRNA expression was similar to water-replete animals, except for NPR-A. Surprisingly, 7 and 14 days of WD caused an up-regulation in the ability of ANP to stimulate cGMP; this also occurred at 14 days for CNP. Taken together, the mRNA expression and peptide mediated guanylyl cyclase activity data after WD were in the opposite direction to what was predicted. Interestingly, after 28 days of WD, most parameters were similar to those of water-replete animals, which indicates that a down-regulation of the NP system is not part of the physiological response to an absence of free water in N. alexis.

The makings of a reliable interview with a child witness

This paper briefly describes four essential elements of interviews involving children, where the primary goal is to obtain detailed and accurate information about an event (e.g., an alleged incident of sexual abuse). These elements include (a) the establishment of a good rapport with the child, (b) a clear description of the purpose and ground-rules of the interview, (c) objectivity and open-mindness, and (d) effective questioning skills. A rationale for the importance of each of these elements and practical recommendations are offered.

An experimental investigation of pure voting power

We evaluate the accuracy of power indices by experimentally measuring the political power embodied in blocks of votes per se.  The experiment incorporates several players interacting in online chat rooms under supervision.  The chat rooms and the selection process reduce or eliminate extraneous political forces leaving logrolling as the primary political force.  Results show that two standard power indices reflect voting power while other power indices and proportionality do not.

The value of information in an agency model with moral hazard

I show that the principal and the agent may each prefer that the principal or the agent has imperfect information about the principal's technology in a principal-agent environment with moral hazard. Principals expend considerable resources on data cumulation and analysis. However, such investments in information acquisition are benecial only if the agent will know that the principal is not ignorant or it allows the principal to implement a dierent action. When the principal is perfectly informed about her technology, the agent prefers to be ignorant. In addition, the value of perfect information for the agency is negative if the principal would implement the same action with either possible technology. I also investigate the dierences between ex ante and ex post contracting, and the ramications of the principal being ignorant or potentially ignorant about the technology. Finally, I determine if the principal's utility varies continuously with the degree of informativeness of the agent about the principal's technology. In this vein, I determine whether the agent's uncertainty may make the principal better o if she has the less informative technology.

Mental tactility: the ascendance of writing in online management education

A qualitative study of online management education and the role of writing as an indicative measure of thinking and learning. Established educational models, such as Dale's Cone of Experience, are expanded and redeveloped to illustrate the central role of writing as a critical thinking process which appears to be increasing, rather than decreasing, with the advent of online multimedia technology. In an environment of increasing reliance on audiovisual stimulus in online education, the authors contend that tertiary educators may witness an ascendance or re-emergence of writing as central to the academic experience. This may be both supply and demand driven. Drawing on a study of two undergraduate units in the Bachelor of Commerce and applying hermeneutics to develop challenging insights, the authors present a case for educators to remain conversant with the art of teaching writing, and to promote writing to improve educational outcomes.

Designing educational tasks for success in industry: a reflection on the evolution of business communication studies in tertiary education

This paper is the result of a "Rip Van Winkle" experience I had concerning the teaching of Business Communication. The paper focuses on the remarkable expansion in the curriculum of the traditional "Business Communication" or "Business Writing" course offered by many tertiary institutions around the world. Based on 25 years of personal observation and experience in a number of educational settings, the paper will trace the increasing sophistication and complexity of the study of business communication from one that covered little more than lessons in the design of hardcopy memos, letters, and reports to one that now covers a broad spectrum of topics such as "emotional intelligence," "intercultural communication," "effective public speaking," as well as the effects of purpose and audience on the design of a wide variety of business communications.

An example of an effective task that involves a number of on the job activities is provided in the form of a ready to use assignment that is applicable in a number of contexts.

Rhetorical theory of public relations: opening the door to semiotic and pragmatism approaches

The 2001 Handbook of Public Relations edited by Robert Heath contains a prominent article advocating the use of rhetorical theory or ‘rhetorical enactment rational’ as a fruitful way of advancing theoretical understandings of public relations. In 2004 Heath and Dan Millar edited: Responding to Crisis: A Rhetorical Approach to Crisis Communication. These are the latest excursions into a perspective on public relations reflecting the extensive study of rhetoric in North America. Other examples are Public Relations Inquiry as Rhetorical Criticism (Elwood, 1995); Rhetorical and Critical Approaches to Public Relations (Toth and Heath, 1992); and a chapter Public Relations? No, Relations with Publics: A Rhetorical-Organisational Approach to Contemporary Corporate Communication (Cheney and Dionisopoulos, in Botan and Hazleton (Eds.) 1989).

The conventional notion of rhetoric is argumentation and persuasion stemming from the ancient Greek sophists, such as Aristotle, and from the Romans, particularly Cicero and Quintillion. Rhetoric became a fundamental plank of the trivium of ancient and medieval education: grammar, logic and rhetoric. Then in the 20th century Kenneth Burke, Stephen Toulmin and Chaim Perelman with Lucie Olbrechts-Tyteca extended Aristotle’s suggestion that: “Rhetoric is the counterpart of dialectic” Aristotle (trans. 1991). To use the rhetorical approach to argue that rational discourse cannot describe the world on its own. Instead living, enculturated human beings have to perceive ‘their’ truths. They take a perceptual ‘position’ on reason.

Public relations, is an industry for influencing perceptual ‘positions’. But the study of perception and attempts to influence perception cannot be claimed by rhetorical scholars alone. Semioticians and linguists who take the perspective of linguistic pragmatics also claim this field. This paper takes the example of ‘public relations’ as a focus for the confluence of rhetorical, semiotic and pragmatism approaches to the ‘problematic’ of understanding and truth.

Induction of epithelial to mesenchymal transition in PMC42-LA human breast carcinoma cells by carcinoma-associated fibroblast secreted factors

Background
Breast carcinoma is accompanied by changes in the acellular and cellular components of the microenvironment, the latter typified by a switch from fibroblasts to myofibroblasts.


Methods
We utilised conditioned media cultures, Western blot analysis and immunocytochemistry to investigate the differential effects of normal mammary fibroblasts (NMFs) and mammary cancer-associated fibroblasts (CAFs) on the phenotype and behaviour of PMC42-LA breast cancer cells. NMFs were obtained from a mammary gland at reduction mammoplasty, and CAFs from a mammary carcinoma after resection.


Results
We found greater expression of myofibroblastic markers in CAFs than in NMFs. Medium from both CAFs and NMFs induced novel expression of α-smooth muscle actin and cytokeratin-14 in PMC42-LA organoids. However, although conditioned media from NMFs resulted in distribution of vimentin-positive cells to the periphery of PMC42-LA organoids, this was not seen with CAF-conditioned medium. Upregulation of vimentin was accompanied by a mis-localization of E-cadherin, suggesting a loss of adhesive function. This was confirmed by visualizing the change in active β-catenin, localized to the cell junctions in control cells/cells in NMF-conditioned medium, to inactive β-catenin, localized to nuclei and cytoplasm in cells in CAF-conditioned medium.


Conclusion
We found no significant difference between the influences of NMFs and CAFs on PMC42-LA cell proliferation, viability, or apoptosis; significantly, we demonstrated a role for CAFs, but not for NMFs, in increasing the migratory ability of PMC42-LA cells. By concentrating NMF-conditioned media, we demonstrated the presence of factor(s) that induce epithelial-mesenchymal transition in NMF-conditioned media that are present at higher levels in CAF-conditioned media. Our in vitro results are consistent with observations in vivo showing that alterations in stroma influence the phenotype and behaviour of surrounding cells and provide evidence for a role for CAFs in stimulating cancer progression via an epithelial-mesenchymal transition. These findings have implications for our understanding of the roles of signalling between epithelial and stromal cells in the development and progression of mammary carcinoma.

Residential proximity to school and the active travel choices of parents

Issue addressed: Walking for transport can contribute significantly to health-enhancing physical activity. We examined the prevalence and duration of walking to and from school, together with perceived influences on doing so, among parents of primary school children. Methods: Questionnaires were completed by parents from four primary schools (one government and three private) located in south-east Queensland (n=559; 40% response rate). Results: Eighteen per cent of parents reported walking for at least 10 minutes during journeys to school. Significantly greater proportions of parents with only one car in their household, with a child who attended a government school, with no driver’s licence, who had less than 11 years of education, and lived within two kilometres of the school walked for at least 10 minutes during the school journey. Factors perceived by parents most strongly to influence walking to school were: being physically active; safety concerns for the child walking alone; not having to park; walking being the child’s preferred option; too much motor vehicle traffic; and their child’s age and level of road sense. Conclusions: Despite the overall low prevalence of walking to school by parents, health-enhancing benefits may be achieved even when other modes of transport are used in conjunction with walking.