[Pulmonary lymphangioleiomyomatosis: From pathogenesis to management]

INTRODUCTION

Pulmonary lymphangioleiomyomatosis (LAM) is a rare disease affecting mainly young women.

BACKGROUND

The respiratory manifestations are characterized by a progressive cystic destruction of the lung parenchyma. Extrapulmonary involvement includes benign renal tumours called angiomyolipomas and abdominal lymphatic masses called lymphangioleiomyomas. At the pathological level, the cellular proliferation found in LAM is in part due to the presence of mutations in the tumour suppressor genes TSC1 and TSC2 (Tuberous Sclerosis Complex). These mutations lead to the activation of the mTOR pathway, which is currently the main therapeutic target. mTOR inhibitors such as sirolimus or everolimus have shown a beneficial effect on the decline in pulmonary function and a reduction of angiomyolipoma size, but are necessary in only some patients.

PERSPECTIVES

LAM cells have migratory properties mediated by the formation of new lymphatic vessels. They are also able to secrete metalloproteases, which enhance their invasiveness. Moreover, the expression of estrogen and progesterone receptors by LAM cells suggests a possible role for sex hormones in the pathogenesis of the disease.

CONCLUSION

A better understanding of mTOR-independent mechanisms would allow the development of novel therapeutic approaches.

Advances in the study of transmissible respiratory tumours in small ruminants

Sheep and goats are widely infected by oncogenic retroviruses, namely Jaagsiekte Sheep RetroVirus (JSRV) and Enzootic Nasal Tumour Virus (ENTV). Under field conditions, these viruses induce transformation of differentiated epithelial cells in the lungs for Jaagsiekte Sheep RetroVirus or the nasal cavities for Enzootic Nasal Tumour Virus. As in other vertebrates, a family of endogenous retroviruses named endogenous Jaagsiekte Sheep RetroVirus (enJSRV) and closely related to exogenous Jaagsiekte Sheep RetroVirus is present in domestic and wild small ruminants. Interestingly, Jaagsiekte Sheep RetroVirus and Enzootic Nasal Tumour Virus are able to promote cell transformation, leading to cancer through their envelope glycoproteins. In vitro, it has been demonstrated that the envelope is able to deregulate some of the important signaling pathways that control cell proliferation. The role of the retroviral envelope in cell transformation has attracted considerable attention in the past years, but it appears to be highly dependent of the nature and origin of the cells used. Aside from its health impact in animals, it has been reported for many years that the Jaagsiekte Sheep RetroVirus-induced lung cancer is analogous to a rare, peculiar form of lung adenocarcinoma in humans, namely lepidic pulmonary adenocarcinoma. The implication of a retrovirus related to Jaagsiekte Sheep RetroVirus is still controversial and under investigation, but the identification of an infectious agent associated with the development of lepidic pulmonary adenocarcinomas might help us to understand cancer development. This review explores the mechanisms of induction of respiratory cancers in small ruminants and the possible link between retrovirus and lepidic pulmonary adenocarcinomas in humans.

Can DVD simulations provide an effective alternative for paramedic clinical placement education?

OBJECTIVE

This study aimed to evaluate the usability of DVD simulations, the impact on student learning satisfaction and the potential for using DVD simulations to reduce the clinical placement burden on the current healthcare system. The clinical DVD simulations were underpinned by interprofessional educational principles that supported clinical placements for paramedic students.

METHOD

Eleven DVD simulations were developed by academic staff members from Monash University with input and feedback from a team of healthcare professionals. Students (N = 97) from the Bachelor of Emergency Health at Monash University viewed the DVD simulations. Students' perceptions, attitudes and thoughts about the clinical relevance of the simulations were assessed by completing a standardised self-report 7-point Likert scale questionnaire (7 indicating the highest satisfaction score). Qualitative data assessing if and how the DVD simulations had influenced paramedic students' clinical placement learning experiences were also collected via two focus groups (n = 6).

RESULTS

Overall, paramedic students positively perceived the DVD simulations with relation to learning satisfaction (mean (SD) 5.14 (1.14), 95% CI 4.91 to 5.37) and information processing quality (mean (SD) 5.50 (0.83), 95% CI 5.33 to 5.67). The simulations maintained students' attention and concentration (mean (SD) 4.35 (0.95), 95% CI 4.15 to 4.54) and provided clinical authenticity and relevance to practice (mean (SD) 4.27 (0.65), 95% CI 4.14 to 4.40). A number of themes emerged from the focus group data including the impact on employment, greater appreciation of healthcare teamwork and notion of interdisciplinary teamwork, the fact that DVD simulations have the capacity to replace some clinical placement rotations and should be integrated into standard curriculum, and that varying amounts of learning wastage occur during clinical placements.

CONCLUSIONS

DVD simulations with an interprofessional education focus were developed. Paramedic students reported the simulations as being educationally, professionally and clinically relevant. The students also identified some aspects of current clinical placements that may be replaced by using DVD simulations. The cost benefit of using interprofessional DVD simulations to supplement and replace certain clinical placement rotations should be investigated further.

Telomerase activation in a model of lung adenocarcinoma

Ovine pulmonary adenocarcinoma (OPA) is a lung cancer strikingly similar to the pneumonic-type mixed invasive adenocarcinoma with a predominant bronchioloalveolar component in humans. Telomerase activity in OPA and the potential involvement of the kinase Akt in telomerase activation and regulation of cell proliferation were investigated. Lung tissues were collected from sheep with a histopathological diagnosis of OPA or controls. Epithelial cell cultures were derived in vitro from lung tissues. Telomerase activity was evaluated using the telomeric repeat amplification protocol method. Phosphorylation of Akt was detected by Western blotting. Telomerase activity was significantly higher in OPA lung tissues compared to control lung tissues. A high telomerase activity was detected in eight out of 12 (67%) primary cell cultures derived from tumours. A high level of expression of phosphorylated Akt was found in 10 out of 27 (37%) tumours, with abolition of Akt activation in response to epidermal growth factor stimulation demonstrated in primary cell cultures derived from tumours. Telomerase activation takes place in ovine pulmonary adenocarcinoma tumour cells and may be partly attributable to Akt activation. Telomerase may inhibit cellular senescence and contribute to the accumulation of tumour cells in mixed adenocarcinoma with a bronchioloalveolar component. Further work is necessary to identify alternative signalling pathways of telomerase activation in tumours.

Ex vivo propagation of infectious sheep scrapie agent in heterologous epithelial cells expressing ovine prion protein

Transmissible spongiform encephalopathies, or prion diseases, are fatal degenerative disorders of the central nervous system that affect humans and animals. Prions are nonconventional infectious agents whose replication depends on the host prion protein (PrP). Transmission of prions to cultured cells has proved to be a particularly difficult task, and with a few exceptions, their experimental propagation relies on inoculation to laboratory animals. Here, we report on the development of a permanent cell line supporting propagation of natural sheep scrapie. This model was obtained by stable expression of a tetracycline-regulatable ovine PrP gene in a rabbit epithelial cell line. After exposure to scrapie agent, cultures were repeatedly found to accumulate high levels of abnormal PrP (PrPres). Cell extracts induced a scrapie-like disease in transgenic mice overexpressing ovine PrP. These cultures remained healthy and stably infected upon subpassaging. Such data show that (i) cultivated cells from a nonneuronal origin can efficiently replicate prions; and (ii) species barrier can be crossed ex vivo through the expression of a relevant PrP gene. This approach led to the ex vivo propagation of a natural transmissible spongiform encephalopathy agent (i.e., without previous experimental adaptation to rodents) and might be applied to human or bovine prions.

Evidence that Wallerian degeneration and localized axon degeneration induced by local neurotrophin deprivation do not involve caspases

The selective degeneration of an axon, without the death of the parent neuron, can occur in response to injury, in a variety of metabolic, toxic, and inflammatory disorders, and during normal development. Recent evidence suggests that some forms of axon degeneration involve an active and regulated program of self-destruction rather than a passive "wasting away" and in this respect and others resemble apoptosis. Here we investigate whether selective axon degeneration depends on some of the molecular machinery that mediates apoptosis, namely, the caspase family of cysteine proteases. We focus on two models of selective axon degeneration: Wallerian degeneration of transected axons and localized axon degeneration induced by local deprivation of neurotrophin. We show that caspase-3 is not activated in the axon during either form of degeneration, although it is activated in the dying cell body of the same neurons. Moreover, caspase inhibitors do not inhibit or retard either form of axon degeneration, although they inhibit apoptosis of the same neurons. Finally, we cannot detect cleaved substrates of caspase-3 and its close relatives immunocytochemically or caspase activity biochemically in axons undergoing Wallerian degeneration. Our results suggest that a neuron contains at least two molecularly distinct self-destruction programs, one for caspase-dependent apoptosis and another for selective axon degeneration.

Conformational study in water by NMR and molecular modeling of cyclic glutamic acid analogues as probes of vitamin K dependent carboxylase

The conformational analysis of four glutamic acid analogues containing a cyclopentyl or cyclohexyl ring, substituted in position 1 by a BOC protected amino group and a methyl ester group and in position 3 by a free carboxylate group, has been carried out in an aqueous environment, by 1H and 13C NMR spectroscopy, and molecular dynamics (MD). Their structural properties were under investigation for a structure-activity relationship analysis to determine the preferred conformation in the carboxylase active site. For each compounds, resulting conformations from NMR and MD data were analyzed and classified according to the dihedral angles chi 1 and chi 2, the distances and the spatial distribution involving charged or substituted C- and N-terminal groups. A reduced number of conformational families were found to be in qualitative agreement with NMR and MD data. A comparison between these different classes of the active and nonactive derivatives was achieved.

Prescription pricing across Canada (Part II)

The first of a two part article entitled "Prescription Pricing Across Canada" appeared in the June issue of CPJ. The article was prompted by recent press reports of a prescription drug study commissioned by the Saskatchewan government, and the consequent attention-getting headlines. The first article dealt with the Western provinces. The second part discusses prescription pricing in Ontario, Québec, New Brunswick, Nova Scotia, Prince Edward Island, Newfoundland, and the Northwest Territories.