Reforms of the pre-graduate curriculum for medical students: the Bologna process and beyond.

For several years, all five medical faculties of Switzerland have embarked on a reform of their training curricula for two reasons: first, according to a new federal act issued in 2006 by the administration of the confederation, faculties needed to meet international standards in terms of content and pedagogic approaches; second, all Swiss universities and thus all medical faculties had to adapt the structure of their curriculum to the frame and principles which govern the Bologna process. This process is the result of the Bologna Declaration of June 1999 which proposes and requires a series of reforms to make European Higher Education more compatible and comparable, more competitive and more attractive for Europeans students. The present paper reviews some of the results achieved in the field, focusing on several issues such as the shortage of physicians and primary care practitioners, the importance of public health, community medicine and medical humanities, and the implementation of new training approaches including e-learning and simulation. In the future, faculties should work on several specific challenges such as: students' mobility, the improvement of students' autonomy and critical thinking as well as their generic and specific skills and finally a reflection on how to improve the attractiveness of the academic career, for physicians of both sexes.

Developmental critical period in gentic redox dysregulation: animal and human studies in schizophrenia

Converging evidence favors an abnormal susceptibility to oxidative stress in schizophrenia. Decreased levels of glutathione (GSH), the major cellular antioxidant and redox regulator, was observed in cerebrospinal-fluid and prefrontal cortex of patients. Importantly, abnormal GSH synthesis of genetic origin was observed: Two case-control studies showed an association with a GAG trinucleotide repeat (TNR) polymorphism in the GSH key synthesizing enzyme glutamate-cysteine-ligase (GCL) catalytic subunit (GCLC) gene. The most common TNR genotype 7/7 was more frequent in controls, whereas the rarest TNR genotype 8/8 was three times more frequent in patients. The disease associated genotypes (35% of patients) correlated with decreased GCLC protein, GCL activity and GSH content. Similar GSH system anomalies were observed in early psychosis patients. Such redox dysregulation combined with environmental stressors at specific developmental stages could underlie structural and functional connectivity anomalies. In pharmacological and knock-out (KO) models, GSH deficit induces anomalies analogous to those reported in patients. (a) morphology: spine density and GABA-parvalbumine immunoreactivity (PV-I) were decreased in anterior cingulate cortex. KO mice showed delayed cortical PV-I at PD10. This effect is exacerbated in mice with increased DA from PD5-10. KO mice exhibit cortical impairment in myelin and perineuronal net known to modulate PV connectivity. (b) physiology: In cultured neurons, NMDA response are depressed by D2 activation. In hippocampus, NMDA-dependent synaptic plasticity is impaired and kainate induced g-oscillations are reduced in parallel to PV-I. (c) cognition: low GSH models show increased sensitivity to stress, hyperactivity, abnormal object recognition, olfactory integration and social behavior. In a clinical study, GSH precursor N-acetyl cysteine (NAC) as add on therapy, improves the negative symptoms and decreases the side effects of antipsychotics. In an auditory oddball paradigm, NAC improves the mismatched negativity, an evoked potential related to pre-attention and to NMDA receptors function. In summary, clinical and experimental evidence converge to demonstrate that a genetically induced dysregulation of GSH synthesis combined with environmental insults in early development represent a major risk factor contributing to the development of schizophrenia Conclusion Based on these data, we proposed a model for PSIP1 promoter activity involving a complex interplay between yet undefined regulatory elements to modulate gene expression.

Anaesthetics, Pain Relief and Critical Care Follow Up (PDF 797 KB)

In 2003/2004 the Department of Health, Social Services and Public Safety commissioned a value for money follow-up audit of Anaesthetics, Pain Relief and Critical Care (APRCC) services at twelve Trusts and covering fourteen hospital sites. The original study had reported in 1999/2000. Detailed follow-up reports, together with action plans have been agreed locally with Trusts. The objectives of the follow-up review were to: • Ascertain the progress made in implementing recommendations from the original study; • Provide data to compare performance across Trusts in areas such as: - Pre-operative assessments; - Organisation of post-operative pain relief; - Organisation of chronic pain services; - Levels of admissions to critical care units; - Occupancy in critical care units; and åÊ • Assess the extent of progress made by Trusts in the implementation of the Chief Medical Officer’s (CMO) recommendations from ‘Facing the Future –Building on the Lessons of Winter 1999/2000’. To enable comparisons across Trusts, data was collected for the financial year 2002/2003. In addition, relevant findings from the Audit Commission’s Acute Hospitals Portfolio have also been included. The Acute Hospital Portfolio is a collection of reviews that are undertaken at acute and specialist Trusts. They focus on key service areas and are reported along the key performance criteria of patient experience, efficiency and capacity. åÊ

Protective CD8+ T cell responses against the pre-erythrocytic stages of malaria parasites: an overview

CD8+ T cells have been implicated as critical effector cells in protection against the pre-erythrocytic stage of malaria in mice and humans following irradiated sporozoite immunization. Immunization experiments in animal models by several investigators have suggested different strategies for vaccination against malaria and many of the targets from liver stage malaria antigens have been shown to be immunogenic and to protect mice from the sporozoite challenge. Several prime/boost protocols with replicating vectors, such as vaccinia/influenza, with non-replicating vectors, such as recombinant particles derived from yeast transposon (Ty-particles) and modified vaccinia virus Ankara, and DNA, significantly enhanced CD8+ T cell immunogenicity and also the protective efficacy against the circumsporosoite protein of Plasmodium berghei and P. yeti. Based on these experimental results the development of a CD8+ T cell inducing vaccine has moved forward from epitope identification to planning stages of safety and immunogenicity trials of candidate vaccines.

Speech by Mr Micheál Martin TD at Launch of Pre-Registration Nursing Degree Programme

Good afternoon ladies and gentlemen. I am very pleased that you were all able to accept my invitation to join me here today on this landmark occasion for nursing education. It is fitting that all of the key stakeholders from the health and education sectors should be so well represented at the launch of an historic new development. Rapid and unpredictable change throughout society has been the hallmark of the twenty-first century, and healthcare is no exception. Regardless of what change occurs, no one doubts that nursing is intrinsic to the health of this nation. However, significant changes in nurse education are now needed if the profession is to deliver on its social mandate to promote people´s health by providing excellent and sensitive care. As science, technology and the demands of the public for sophisticated and responsive health care become increasingly complex, it is essential that the foundation of nursing education is redesigned. Pre-registration nursing education has already undergone radical change over the past eight years, during which time it has moved from an apprenticeship model of education and training to a diploma based programme firmly rooted in higher education. The Secretary General of my Department, Michael Kelly, played a leading role in bringing about this transformation, which has greatly enhanced the way students are prepared for entry to the nursing profession. The benefits of the revised model of education are clearly evident from the quality of the nurses graduating from the diploma programme. The Commission on Nursing examined the whole area of nursing education, and set out a very convincing case for educating nursing students to degree level. It argued that nurses of the future would be required to possess increased flexibility and the ability to work autonomously. A degree programme would provide nurses with a theoretical underpinning that would enable them to develop their clinical skills to a greater extent and to respond to future challenges in health care, for the benefit of patients and clients of the health services. The Commission has provided a solid framework for the professional development of nurses and midwives, including a process that is already underway for the creation of clinical nurse specialist and advanced nurse practitioner posts. This process will facilitate the transfer of skills across divisions of nursing. In this scenario, it is clearly desirable that the future benchmark qualification for registration as a nurse should be a degree in nursing studies. A Nursing Education Forum was established in early 1999 to prepare a strategic framework for the implementation of a nursing degree programme. When launching the Forum´s report last January, I indicated that the Government had agreed in principle to the introduction of the proposed degree programme next year. At the time two substantial outstanding issues had yet to be resolved, namely the basis on which nurse teachers would transfer from the health sector to the education sector and the amount of capital and revenue funding required to operate the degree programme. My Department has brokered agreements between the Nursing Alliance and the Higher Education Institutions for the assimilation of nurse teachers as lecturers into their affiliated institutions. The terms of these agreements have been accepted by all four nursing unions following a ballot of their nurse teacher members. I would like to pay particular tribute to all nurse teachers who have contributed to shaping the position, relevance and visibility of nursing through leadership, which embodies scholarship and excellence in the profession of nursing itself. In response to a recommendation of the Nursing Education Forum, I established an Inter-Departmental Steering Committee, chaired by Bernard Carey of my Department, to consider all the funding and policy issues. This Steering Committee includes representatives of the Department of Finance and the Department of Education and Science as well as the Higher Education Authority. The Steering Committee has been engaged in intensive negotiations with representatives of the Conference of Heads of Irish Universities and the Institutes of Technology in relation to their capital and revenue funding requirements. These negotiations were successfully concluded within the past few weeks. The satisfactory resolution of the industrial relations and funding issues cleared the way for me to go to the Government with concrete proposals for the implementation of degree level education for nursing students. I am delighted to announce here today that the Government has approved all of my proposals, and that a four-year undergraduate pre-registration nursing degree programme will be implemented on a nation-wide basis at the start of the next academic year, 2002/2003. The Government has approved the provision of capital funding totalling £176 million pounds for a major building and equipment programme to facilitate the full integration of nursing students into the higher education sector. This programme is due to be completed by September 2004, and will ensure that nursing students are accommodated in purpose built schools of nursing studies with state of the art clinical skills and human science laboratories at thirteen higher education sites throughout the country. The Government has also agreed to make available the substantial additional revenue funding required to support the nursing degree programme. By 2006, the full year cost of operating the programme will rise to some £43 million pounds. The scale of this investment in pre-registration nursing education is enormous by any yardstick. It demonstrates the firm commitment of myself and my Government colleagues to the full implementation of the recommendations of the Commission on Nursing, of which the introduction of pre-registration degree level education is arguably the most important. This historic decision, and it is truly historic, will finally put the education of nurses on a par with the education of other health care professionals. The nursing profession has long been striving for parity, and my own involvement in the achievement of it is a matter of deep personal satisfaction to me. I am also pleased to announce that the Government has approved my plans for increasing the number of nursing training places to coincide with the implementation of the degree programme next year. Ninety-three additional places in mental handicap and psychiatric nursing will be created at Athlone, Letterkenny, Tralee and Waterford Institutes of Technology. This will yield 392 extra places over the four years of the degree programme. A total of 1,640 places annually on the new degree programme will thus be available. This is an all-time record, and maintaining the annual student intake at this level for the foreseeable future is a key element of my overall strategy for ensuring that we produce sufficient “home-grown” nurses for our health services. I am aware that the Nursing Alliance were anxious that some funding would be provided for the further academic career development of nurse teachers who transfer to one of the six Universities that will be involved in the delivery of the degree programme. I am happy to confirm that up to £300,000 in total per year will be available for this purpose over the first four years of the degree programme. In line with a recommendation of the Commission on Nursing, my Department will have responsibility for the administration of the nursing degree budget until the programme has been bedded down in the higher education sector. A primary concern will be to ensure that the substantial capital and revenue funding involved is ring-fenced for nursing studies. It is intended that responsibility for the budget will be transferred to the Department of Education and Science after the first cohort of nursing degree students have graduated in 2006. In the context of today´s launch, it is relevant to refer to a special initiative that I introduced last year to assist registered nurses wishing to undertake part-time nursing degree courses. Under this initiative, nurses are entitled to have their course fees paid by their employers in return for a commitment to continue working in the public health service for a period following completion of the course. This initiative has proved extremely popular with large numbers of nurses availing of it. I want to confirm here today that the free fees initiative will continue in operation until 2005, at a total cost of at least £15 million pounds. I am giving this commitment in order to assure this year´s intake of nursing students to the final diploma programmes that fee support for a part-time nursing degree course will be available to them when they graduate in three years time. The focus of today´s celebration is rightly on the landmark Government decision to implement the nursing degree programme next year. As Minister for Health and Children, and as a former Minister for Education, I also have a particular interest in the educational opportunities available to other health service workers to upgrade their skills. I am pleased to announce that the Government has approved my proposals for the introduction of a sponsorship scheme for suitable, experienced health care assistants who wish to become nurses. This new scheme will commence next year and will be administered by the health boards. Successful applicants will be allowed to retain their existing salaries throughout the four years of the degree programme in return for a commitment to work as nurses for their health service employer for a period of five years following registration. Up to forty sponsorships will be available annually. The new scheme will enable suitable applicants to undertake nursing education and training without suffering financial hardship. The greatest advantage of the scheme will be the retention by the public health service of staff who are supported under it, since they will have had practical experience of working in the service and their own personal commitment to upgrading their skills will be informed by that experience. I am confident that the sponsorship scheme will be warmly welcomed by health service unions representing care assistants as providing an exciting new career development path for their members. Education and health are now the two pillars upon which the profession of nursing rests. We must continue to build bridges, even tunnels where needed to strengthen this partnership. We must all understand partnerships donâ?Tt just happen they are designed and must be worked at. The changes outlined here today are powerful incentives for those in healthcare agencies, academic institutions and regulatory bodies to design revolutionary programmes capable of shaping a critical mass of excellent practitioners. You have an opportunity, greater perhaps than has been granted to any other generation in history to make certain those changes are for the good. Ultimately changes that will make the country a healthier and more equitable place to live. The challenge relates to building a seamless preparatory programme which equally respects both education and practise as an indivisible duo whilst ensuring that high tech does not replace the human touch. This is a special day in the history of the development of the Irish nursing profession, and I would like to thank everybody for their contribution. I want to express my particular appreciation of two people who by this stage are well known to all of you – Bernard Carey of my Department and Siobhán O´Halloran of the National Implementation Committee. Bernard and Siobhán have devoted considerable time and energy to the project on my behalf over the past fourteen months or so. That we are here today celebrating the launch of degree level education is due in no small part to their successful execution of the mandate that I gave them. We live in a rapidly changing world, one in which nursing can no longer rely on systems of the past to guide it through the new millennium. In terms of contemporary healthcare, nursing is no longer just a reciprocal kindness but rather a highly complex set of professional behaviours, which require serious educational investment. Pre-registration nurse education will always need development and redesign to ensure our health care system meets the demands of modern society. Nothing is finite. Today more than ever the health system is dependent on the resourcefulness of nursing. I have no doubt that the new educational landscape painted will ensure that nurses of the future will be increasingly innovative, independent and in demand. The unmistakable message from my Department is that nursing really matters. Thank you.

Is (1→3)-β-D-glucan the missing link from bedside assessment to pre-emptive therapy of invasive candidiasis?

ABSTRACT: Invasive candidiasis is a frequent life-threatening complication in critically ill patients. Early diagnosis followed by prompt treatment aimed at improving outcome by minimizing unnecessary antifungal use remains a major challenge in the ICU setting. Timely patient selection thus plays a key role for clinically efficient and cost-effective management. Approaches combining clinical risk factors and Candida colonization data have improved our ability to identify such patients early. While the negative predictive value of scores and predicting rules is up to 95 to 99%, the positive predictive value is much lower, ranging between 10 and 60%. Accordingly, if a positive score or rule is used to guide the start of antifungal therapy, many patients may be treated unnecessarily. Candida biomarkers display higher positive predictive values; however, they lack sensitivity and are thus not able to identify all cases of invasive candidiasis. The (1→3)-β-D-glucan (BG) assay, a panfungal antigen test, is recommended as a complementary tool for the diagnosis of invasive mycoses in high-risk hemato-oncological patients. Its role in the more heterogeneous ICU population remains to be defined. More efficient clinical selection strategies combined with performant laboratory tools are needed in order to treat the right patients at the right time by keeping costs of screening and therapy as low as possible. The new approach proposed by Posteraro and colleagues in the previous issue of Critical Care meets these requirements. A single positive BG value in medical patients admitted to the ICU with sepsis and expected to stay for more than 5 days preceded the documentation of candidemia by 1 to 3 days with an unprecedented diagnostic accuracy. Applying this one-point fungal screening on a selected subset of ICU patients with an estimated 15 to 20% risk of developing candidemia is an appealing and potentially cost-effective approach. If confirmed by multicenter investigations, and extended to surgical patients at high risk of invasive candidiasis after abdominal surgery, this Bayesian-based risk stratification approach aimed at maximizing clinical efficiency by minimizing health care resource utilization may substantially simplify the management of critically ill patients at risk of invasive candidiasis.

A critical lineage-nonspecific role for pTalpha in mediating allelic and isotypic exclusion in TCRbeta-transgenic mice.

Although it is well established that early expression of TCRbeta transgenes in the thymus leads to efficient inhibition of both endogenous TCRbeta and TCRgamma rearrangement (also known as allelic and "isotypic" exclusion, respectively) the role of pTalpha in these processes remains controversial. Here, we have systematically re-evaluated this issue using three independent strains of TCRbeta-transgenic mice that differ widely in transgene expression levels, and a sensitive intracellular staining assay that detects endogenous TCRVbeta expression in individual immature thymocytes. In the absence of pTalpha, both allelic and isotypic exclusion were reversed in all three TCRbeta-transgenic strains, clearly demonstrating a general requirement for pre-TCR signaling in the inhibition of endogenous TCRbeta and TCRgamma rearrangement. Both allelic and isotypic exclusion were pTalpha dose dependent when transgenic TCRbeta levels were subphysiological. Moreover, pTalpha-dependent allelic and isotypic exclusion occurred in both alphabeta and gammadelta T cell lineages, indicating that pre-TCR signaling can potentially be functional in gammadelta precursors. Finally, levels of endogenous RAG1 and RAG2 were not down-regulated in TCRbeta-transgenic immature thymocytes undergoing allelic or isotypic exclusion. Collectively, our data reveal a critical but lineage-nonspecific role for pTalpha in mediating both allelic and isotypic exclusion in TCRbeta-transgenic mice.

The quest for a message: budding yeast, a model organism to study the control of pre-mRNA splicing

Removal of introns during pre-mRNA splicing is a critical process in gene expression, and understanding its control at both single-gene and genomic levels is one of the great challenges in Biology. Splicing takes place in a dynamic, large ribonucleoprotein complex known as the spliceosome. Combining Genetics and Biochemistry, Saccharomyces cerevisiae provides insights into its mechanisms, including its regulation by RNA-protein interactions. Recent genome-wide analyses indicate that regulated splicing is broad and biologically relevant even in organisms with a relatively simple intronic structure, such as yeast. Furthermore, the possibility of coordination in splicing regulation at genomic level is becoming clear in this model organism. This should provide a valuable system to approach the complex problem of the role of regulated splicing in genomic expression.

Physical quality of an Oxisol cultivated with maize submited to cover crops in the pre-cropping period

The intensive use of land alters the distribution of the pore size which imparts consequences on the soil physical quality. The Least Limiting Water Range (LLWR) allows for the visualization of the effects of management systems upon either the improvement or the degradation of the soil physical quality. The objective of this study was to evaluate the physical quality of a Red Latosol (Oxisol) submited to cover crops in the period prior to the maize crop in a no-tillage and conventional tillage system, using porosity, soil bulk density and the LLWR as attributes. The treatments were: conventional tillage (CT) and a no-tillage system with the following cover crops: sunn hemp (Crotalaria juncea L.) (NS), pearl millet (Pennisetum americanum (L.) Leeke) (NP) and lablab (Dolichos lablab L.) (NL). The experimental design was randomized blocks in subdivided plots with six replications, with the plots being constituted by the treatments and the subplots by the layers analyzed. The no-tillage systems showed higher total porosity and soil organic matter at the 0-0.5 m layer for the CT. The CT did not differ from the NL or NS in relation to macroporosity. The NP showed the greater porosity, while CT and NS presented lower soil bulk density. No < 10 % airing porosity was found for the treatments evaluated, and value for water content where soil aeration is critical (θPA) was found above estimated water content at field capacity (θFC) for all densities. Critical soil bulk density was of 1.36 and 1.43 Mg m-3 for NP and CT, respectively. The LLWR in the no-tillage systems was limited in the upper part by the θFC, and in the bottom part, by the water content from which soil resistance to penetration is limiting (θPR). By means of LLWR it was observed that the soil presented good physical quality.

Some critical reflections on Michel Foucault's reading of Plutarch's Eroticus (Amatorius)

This aim of this article is to reflect on Michel Foucault's reading of Plutarch's Eroticus in his Histoire de la sexualité, putting emphasis on the fact that, against what it is affirmed by the French thinker, the real debate is not, in the author's opinion, about true pleasure, that obtained by the erastés from his erómenos or that obtained by husbands from their wives, but the need to assign also love and friendship (éros kaì philia) to the conjugal love.

Urinalysis and pre-renal acute kidney injury: time to move on.

Urinary indices are classically believed to allow differentiation of transient (or pre-renal) acute kidney injury (AKI) from persistent (or acute tubular necrosis) AKI. However, the data validating urinalysis in critically ill patients are weak. In the previous issue of Critical Care, Pons and colleagues demonstrate in a multicenter observational study that sodium and urea excretion fractions as well as urinary over plasma ratios performed poorly as diagnostic tests to separate such entities. This study confirms the limited diagnostic and prognostic ability of urine testing. Together with other studies, this study raises more fundamental questions about the value, meaning and pathophysiologic validity of the pre-renal AKI paradigm and suggests that AKI (like all other forms of organ injury) is a continuum of injury that cannot be neatly divided into functional (pre-renal or transient) or structural (acute tubular necrosis or persistent).

A critical analysis of three psychological research programs of doping behaviour

Objectives To consider the various specific substances-taking activities in sport an examination of three psychological models of doping behaviour utilised by researchers is presented in order to evaluate their real and potential impact, and to improve the relevance and efficiency of anti-doping campaigns. Design Adopting the notion of a "research program" (Lakatos, 1978) from the philosophy of science, a range of studies into the psychology of doping behaviour are classified and critically analysed. Method Theoretical and practical parameters of three research programs are critically evaluated (i) cognitive; (ii) drive; and (iii) situated-dynamic. Results The analysis reveals the diversity of theoretical commitments of the research programs and their practical consequences. The «cognitive program» assumes that athletes are accountable for their acts that reflect the endeavour to attain sporting and non-sporting goals. Attitudes, knowledge and rational decisions are understood to be the basis of doping behaviour. The «drive program» characterises the variety of traces and consequences on psychological and somatic states coming from athlete's experience with sport. Doping behaviour here is conceived of as a solution to reduce unconscious psychological and somatic distress. The «situated-dynamic program» considers a broader context of athletes' doping activity and its evolution during a sport career. Doping is considered as emergent and self-organized behaviour, grounded on temporally critical couplings between athletes' actions and situations and the specific dynamics of their development during the sporting life course. Conclusions These hypothetical, theoretical and methodological considerations offer a more nuanced understanding of doping behaviours, making an effective contribution to anti-doping education and research by enabling researchers and policy personnel to become more critically reflective about their explicit and implicit assumptions regarding models of explanations for doping behaviour.

Developmental critical period in genetic redox dysregulation: animal and human studies in schizophrenia

Converging evidence favors an abnormal susceptibility to oxidative stress in schizophrenia. Decreased levels of glutathione (GSH), the major cellular antioxidant and redox regulator, was observed in cerebrospinal-fluid and prefrontal cortex of patients. Importantly, abnormal GSH synthesis of genetic origin was observed: Two case-control studies showed an association with a GAG trinucleotide repeat (TNR) polymorphism in the GSH key synthesizing enzyme glutamate-cysteine-ligase (GCL) catalytic subunit (GCLC) gene. The most common TNR genotype 7/7 was more frequent in controls, whereas the rarest TNR genotype 8/8 was three times more frequent in patients. The disease associated genotypes (35% of patients) correlated with decreased GCLC protein, GCL activity and GSH content. Similar GSH system anomalies were observed in early psychosis patients. Such redox dysregulation combined with environmental stressors at specific developmental stages could underlie structural and functional connectivity anomalies. In pharmacological and knock-out (KO) models, GSH deficit induces anomalies analogous to those reported in patients. (a) morphology: spine density and GABA-parvalbumine immunoreactivity (PV-I) were decreased in anterior cingulate cortex. KO mice showed delayed cortical PV-I at PD10. This effect is exacerbated in mice with increased DA from PD5-10. KO mice exhibit cortical impairment in myelin and perineuronal net known to modulate PV connectivity. (b) physiology: In cultured neurons, NMDA response are depressed by D2 activation. In hippocampus, NMDA-dependent synaptic plasticity is impaired and kainate induced g-oscillations are reduced in parallel to PV-I. (c) cognition: low GSH models show increased sensitivity to stress, hyperactivity, abnormal object recognition, olfactory integration and social behavior. In a clinical study, GSH precursor N-acetyl cysteine (NAC) as add on therapy, improves the negative symptoms and decreases the side effects of antipsychotics. In an auditory oddball paradigm, NAC improves the mismatched negativity, an evoked potential related to pre-attention and to NMDA receptors function. In summary, clinical and experimental evidence converge to demonstrate that a genetically induced dysregulation of GSH synthesis combined with environmental insults in early development represent a major risk factor contributing to the development of schizophrenia

PRPF mutations are associated with generalized defects in spliceosome formation and pre-mRNA splicing in patients with retinitis pigmentosa.

Proteins PRPF31, PRPF3 and PRPF8 (RP-PRPFs) are ubiquitously expressed components of the spliceosome, a macromolecular complex that processes nearly all pre-mRNAs. Although these spliceosomal proteins are conserved in eukaryotes and are essential for survival, heterozygous mutations in human RP-PRPF genes lead to retinitis pigmentosa, a hereditary disease restricted to the eye. Using cells from patients with 10 different mutations, we show that all clinically relevant RP-PRPF defects affect the stoichiometry of spliceosomal small nuclear RNAs (snRNAs), the protein composition of tri-small nuclear ribonucleoproteins and the kinetics of spliceosome assembly. These mutations cause inefficient splicing in vitro and affect constitutive splicing ex-vivo by impairing the removal of at least 9% of endogenously expressed introns. Alternative splicing choices are also affected when RP-PRPF defects are present. Furthermore, we show that the steady-state levels of snRNAs and processed pre-mRNAs are highest in the retina, indicating a particularly elevated splicing activity. Our results suggest a role for PRPFs defects in the etiology of PRPF-linked retinitis pigmentosa, which appears to be a truly systemic splicing disease. Although these mutations cause widespread and important splicing defects, they are likely tolerated by the majority of human tissues but are critical for retinal cell survival.