Cell density alters matrix accumulation in two distinct fractions and the mechanical integrity of alginate-chondrocyte constructs

Chondrocyte density in articular cartilage is known to change with the development and growth of the tissue and may play an important role in the formation of a functional extracellular matrix (ECM). The objective of this study was to determine how initial chondrocyte density in an alginate hydrogel affects the matrix composition, its distribution between the cell-associated (CM) and further removed matrix (FRM) fractions, and the tensile mechanical properties of the developing engineered cartilage. Alginate constructs containing primary bovine chondrocytes at densities of 0, 4, 16, and 64 million cells/ml were fabricated and cultured for 1 or 2 weeks, at which time structural, biochemical, and mechanical properties were analyzed. Both matrix content and distribution varied with the initial cell density. Increasing cell density resulted in an increasing content of collagen and sulfated-glycosaminoglycan (GAG) and an increasing proportion of these molecules localized in the CM. While the equilibrium tensile modulus of cell-free alginate did not change with time in culture, the constructs with highest cell density were 116% stiffer than cell-free controls after 2 weeks of culture. The equilibrium tensile modulus was positively correlated with total collagen (r2 = 0.47, p < 0.001) and GAG content (r2 = 0.68, p < 0.001), and these relationships were enhanced when analyzing only those matrix molecules in the CM fraction (r2 = 0.60 and 0.72 for collagen and GAG, respectively, each p < 0.001). Overall, the results of this study indicate that initial cell density has a considerable effect on the developing composition, structure, and function of alginate–chondrocyte constructs.

Control and protection of a microgrid connected to utility through back-to-back converters

This paper discusses the control and protection of a microgrid that is connected to utility through back-to-back converters. The back-to-back converter connection facilitates bidirectional power flow between the utility and the microgrid. These converters can operate in two different modes–one in which a fixed amount of power is drawn from the utility and the other in which the microgrid power shortfall is supplied by the utility. In the case of a fault in the utility or microgrid side, the protection system should act not only to clear the fault but also to block the back-to-back converters such that its dc bus voltage does not fall during fault. Furthermore, a converter internal mechanism prevents it from supplying high current during a fault and this complicates the operation of a protection system. To overcome this, an admittance based relay scheme is proposed, which has an inverse time characteristic based on measured admittance of the line. The proposed protection and control schemes are able to ensure reliable operation of the microgrid.

Locating child protection in preservice teacher education

A recent report delivered by the Australian Centre for Child Protection has highlighted the need for empirical evidence of effective pedagogies for supporting teaching and learning of child protection content in Australian teacher education programs (Arnold & Maio-Taddeo, 2007). This paper advances this call by presenting case study accounts of different approaches to teaching child protection content in University-based teacher education programs across three Australian States. These different cases provide a basis for understanding existing strategies as an important precursor to improving practice. Although preschool, primary and secondary schools have been involved in efforts to protect children from abuse and neglect since the 1970s, teacher education programs, including preservice and inservice programs, have been slow to align their work with child protection agendas. This paper opens a long-overdue discussion about the extent and nature of child protection content in teacher education and proposes strategies for translating research into practice.

Queensland College of Teachers annual lecture 2010 : child protection

Teachers have a crucial role as “sentinels” for children who have been abused or neglected. This professional development session will provide a framework for understanding the types, incidence and causes of child abuse and neglect, and teachers’ role in reporting suspected cases. The session will provide participants with knowledge and skills to enable them to identify warning signs and indicators of child abuse and neglect, know the basis of their duties to report suspected cases of abuse and neglect, and respond to the needs of abused and neglected children at school. The presentation will focus on: • the reasons why child abuse and neglect can occur; • the different types of child abuse and neglect and their effects on children; • the warning signs and indicators of physical abuse, emotional abuse, sexual abuse and neglect; • applying knowledge of indicators to make judgements about risk of harm; • responding to indications of risk of harm, including complying with legislative and policy-based duties to report suspected child abuse and neglect.

'Attaching' warning statements by facsimile consumer protection prevails!

Section 366 of the Property Agents and Motor Dealers Act 2000 (Qld) (‘PAMDA’) mandates that all contracts for the sale of residential property in Queensland (other than contracts formed on a sale by auction) have a warning statement ‘attached’ as the first or top sheet. Alternative judicial views have emerged concerning the possibility of attaching a warning statement to a contract sent by facsimile. In recognition of the consumer protection nature of the legislation, in MP Management (Aust) Pty Ltd v Churven [2002] QSC 320 Muir J favoured a restrictive view of the word ‘attached’ requiring physical joinder of the warning statement to the relevant contract. In contrast, in MNM Developments Pty Ltd v Gerrard [2005] QDC 10 Newton DCJ opined that the requirements of the PAMDA could be met where the warning statement preceded the contract of sale in a facsimile transmission sent in one continuous stream. Newton DCJ considered that this broader approach promoted commercial convenience. In an appeal from the decision of Newton DCJ, in MNM Developments Pty Ltd v Gerrard [2005] QCA 230 a majority of the Queensland Court of Appeal has held that the restrictive view propounded by Muir J is correct. Notwithstanding possible commercial inconvenience, it is not possible for a warning statement to be attached to a contract sent by facsimile.

Bringing protection home : healing the schism between international obligations and national safeguards created by extraterritorial processing

Extraterritorial processing schemes are designed to prevent and deter access to statutory and judicial safeguards in the country responsible for the interception and transfer of asylum seekers to a third country. In line with this objective, they incorporate interdiction, transfer and processing practices and standards that are deliberately isolated from the national legal and institutional protections within either the intercepting state or the third country where processing occurs. Australia's recent disbandment of its extraterritorial processing centres in third countries highlights the fact that extraterritorial processing schemes have proven unworkable as a matter of international law, as they negate the national safeguards fundamental to the satisfaction of a state's protection obligations.

Removing barriers to protection at the exported border : visas, carrier sanctions, and international obligation

Asylum is being gradually denuded of the national institutional mechanisms (judicial, legislative and administrative) that provide the framework for a fair and effective asylum hearing. In this sense, there is an ongoing ‘denationalization’ or ‘deformalization’ of the asylum process. This chapter critically examines one of the linchpins of this trend: the erection of pre-entry measures at ports of embarkation in order to prevent asylum seekers from physically accessing the territory of the state. Pre-entry measures comprise the core requirement that foreigners possess an entry visa granting permission to enter the state of destination. Visa requirements are increasingly implemented by immigration officials posted abroad or by officials of transit countries pursuant to bilateral agreements (so-called ‘juxtaposed’ immigration controls). Private carriers, which are subject to sanctions if they bring persons to a country who do not have permission to enter, also engage in a form of de facto immigration control on behalf of states. These measures constitute a type of ‘externalized’ or ‘exported’ border that pushes the immigration boundaries of the state as far from its physical boundaries as possible. Pre-entry measures have a crippling impact on the ability of asylum seekers to access the territory of states to claim asylum. In effect, states have ‘externalized’ asylum by replacing the legal obligation on states to protect refugees arriving at ports of entry with what are perceived to be no more than moral obligations towards asylum seekers arriving at the external border of the state.

Transcutaneous immunization with novel lipid-based adjuvants induces protection against gastric Helicobacter pylori infection

The development of vaccines to combat pathogens that infect across mucosal surfaces has been a major goal of vaccine research. Successful mucosal vaccination requires the co-administration of adjuvants that can overcome the state of immune tolerance normally associated with mucosal application of proteins. In the case of oral immunization, delivery systems are also required to protect vaccine antigens against destruction by gastric pH and digestive enzymes. Furthermore, adjuvants used for mucosal delivery must be free of neurotoxic effects like those induced by the commonly used experimental mucosal adjuvant cholera toxin. Maintenance of the "cold chain" is also essential for the effectiveness of any vaccine and adjuvants/delivery systems that enhance the stability of a vaccine would offer a significant advantage. Needle-free methods of vaccination that induce protective immunity at multiple mucosal surfaces are also desirable for rapid vaccination of large populations. In the present study we show that transcutaneous immunization (TCI) using Lipid C, a novel lipid-based matrix originally developed for oral immunization, containing soluble Helicobacter sonicate significantly reduces the gastric bacterial burden in mice following gastric challenge with live Helicobacter pylori. Protection is associated with the production of splenic gamma interferon and gastric IgA and was achieved without the co-administration of potent and potentially toxic adjuvants, although protection was further enhanced by inclusion of CpG-ODN and cholera toxin in the lipid delivery system.

Functional role of cell surface CUB domain-containing protein 1 in tumour cell dissemination

The function of CUB domain-containing protein 1 (CDCP1), a recently described transmembrane protein expressed on the surface of hematopoietic stem cells and normal and malignant cells of different tissue origin, is not well defined. The contribution of CDCP1 to tumor metastasis was analyzed by using HeLa carcinoma cells overexpressing CDCP1 (HeLa-CDCP1) and a high-disseminating variant of prostate carcinoma PC-3 naturally expressing high levels of CDCP1 (PC3-hi/diss). CDCP1 expression rendered HeLa cells more aggressive in experimental metastasis in immunodeficient mice. Metastatic colonization by HeLa-CDCP1 was effectively inhibited with subtractive immunization-generated, CDCP1-specific monoclonal antibody (mAb) 41-2, suggesting that CDCP1 facilitates relatively late stages of the metastatic cascade. In the chick embryo model, time- and dose-dependent inhibition of HeLa-CDCP1 colonization by mAb 41-2 was analyzed quantitatively to determine when and where CDCP1 functions during metastasis. Quantitative PCR and immunohistochemical analyses indicated that CDCP1 facilitated tumor cell survival soon after vascular arrest. Live cell imaging showed that the function-blocking mechanism of mAb 41-2 involved enhancement of tumor cell apoptosis, confirmed by attenuation of mAb 41-2–mediated effects with the caspase inhibitor z-VAD-fmk. Under proapoptotic conditions in vitro, CDCP1 expression conferred HeLa-CDCP1 cells with resistance to doxorubicin-induced apoptosis, whereas ligation of CDCP1 with mAb 41-2 caused additional enhancement of the apoptotic response. The functional role of naturally expressed CDCP1 was shown by mAb 41-2–mediated inhibition of both experimental and spontaneous metastasis of PC3-hi/diss. These findings confirm that CDCP1 functions as an antiapoptotic molecule and indicate that during metastasis CDCP1 facilitates tumor cell survival likely during or soon after extravasation.

The spermostatic and microbicidal actions of quinones and malemides : towards a dual-purpose contraceptive agent

There is an urgent need to develop safe, effective, dual-purpose contraceptive agents that combine the prevention of pregnancy with protection against sexually transmitted diseases. Here we report the identification of a group of compounds that on contact with human spermatozoa induce a state of “spermostasis,” characterized by the extremely rapid inhibition of sperm movement without compromising cell viability. These spermostatic agents were more active and significantly less toxic than the reagent in current clinical use, nonoxynol 9, giving therapeutic indices (ratio of spermostatic to cytotoxic activity) that were orders of magnitude greater than this traditional spermicide. Although certain compounds could trigger reactive oxygen species generation by spermatozoa, this activity was not correlated with spermostasis. Rather, the latter was associated with alkylation of two major sperm tail proteins that were identified as A Kinase-Anchoring Proteins (AKAP3 and AKAP4) by mass spectrometry. As a consequence of disrupted AKAP function, the abilities of cAMP to drive protein kinase A-dependent activities in the sperm tail, such as the activation of SRC and the consequent stimulation of tyrosine phosphorylation, were suppressed. Furthermore, analysis of microbicidal activity using Chlamydia muridarum revealed powerful inhibitory effects at the same low micromolar doses that suppressed sperm movement. In this case, the microbicidal action was associated with alkylation of Major Outer Membrane Protein (MOMP), a major chlamydial membrane protein. Taken together, these results have identified for the first time a novel set of cellular targets and chemical principles capable of providing simultaneous defense against both fertility and the spread of sexually transmitted disease.

Estoppel in the face of consumer protection in land transactions- judicial reasoning or judicial intuition

Nationally, there is much legislation regulating land sale transactions, particularly in relation to seller disclosure of information. The statutes require strict compliance by a seller failing which, in general, a buyer can terminate the contract. In a number of instances, when buyers have sought to exercise these rights, sellers have alleged that buyers have either expressly or by conduct waived their rights to rely upon these statutes. This article examines the nature of these rights in this context, whether they are capable of waiver and, if so, what words or conduct might be sufficient to amount to waiver. The analysis finds that the law is in a very unsatisfactory state, that the operation of those rules that can be identified as having relevance are unevenly applied and concludes that sellers have, in the main, been unsuccessful in defeating buyers' statutory rights as a result of an alleged waiver by those buyers.