Effectiveness of a symptom-clinic intervention delivered by general practitioners with an extended role for people with multiple and persistent physical symptoms in England: the Multiple Symptoms Study 3 pragmatic, multicentre, parallel-group, individually randomised controlled trial.

BACKGROUND: People with multiple and persistent physical symptoms have impaired quality of life and poor experiences of health care. We aimed to evaluate the effectiveness of a community-based symptom-clinic intervention in people with multiple and persistent physical symptoms, hypothesising that this symptoms clinic plus usual care would be superior to usual care only. METHODS: The Multiple Symptoms Study 3 was a pragmatic, multicentre, parallel-group, individually randomised controlled trial conducted in 108 general practices in the UK National Health Service in four regions of England between Dec 6, 2018, and June 30, 2023. Participants were individually randomised (1:1) to the symptom-clinic intervention plus usual care or to usual care only via a computer-generated, pseudo-random list stratified by trial centre. Allocation was done by the trial statistician and concealed with a centralised, web-based randomisation system; masking participants was not possible due to the nature of the intervention. The symptom-clinic intervention was a sequence of up to four medical consultations that aimed to elicit a detailed clinical history, fully hear and validate the participant, offer rational explanations for symptoms, and assist the participant to develop ways of managing their symptoms; it was delivered by general practitioners with an extended role. The primary outcome was Patient Health Questionnaire-15 (PHQ-15) score 52 weeks after randomisation, analysed by intention to treat. The trial is registered on the ISRCTN registry (ISRCTN57050216). FINDINGS: 354 participants were randomly assigned; 178 (50%) were assigned to receive the community-based symptoms clinic plus usual care and 176 (50%) were assigned to receive usual care only. At the primary-outcome point of 52 weeks, PHQ-15 scores were 14·1 (SD 3·7) in the group receiving usual care and 12·2 (4·5) in the group receiving the intervention. The adjusted between-group difference of -1·82 (95% CI -2·67 to -0·97) was statistically significantly in favour of the intervention group (p<0·0001). There were 39 adverse events in the group receiving usual care and 36 adverse events in the group receiving the intervention. There were no statistically significant between-group differences in the proportion of participants who had non-serious adverse events (-0·03, 95% CI -0·11 to 0·05) or serious adverse events (0·02, -0·02 to 0·07). No serious adverse event was deemed to be related to the trial intervention. INTERPRETATION: Our symptom-clinic intervention, which focused on explaining persistent symptoms to participants in order to support self-management, led to sustained improvement in multiple and persistent physical symptoms. FUNDING: UK National Institute for Health and Care Research.

A Drosophila model for mechanistic investigation of tau protein spread.

Brain protein aggregates are a hallmark of neurodegenerative disease. Previous work indicates that specific protein components of these aggregates are toxic, including tau in Alzheimer's disease and related tauopathies. Increasing evidence also indicates that these toxic proteins traffic between cells in a prion-like fashion, thereby spreading pathology from one brain region to another. However, the mechanisms involved in trafficking are poorly understood. We therefore developed a transgenic Drosophila model to facilitate rapid evaluation of candidate tau trafficking modifiers. Our model uses the bipartite Q system to drive co-expression of tau and GFP in the fly eye. We find age-dependent tau spread into the brain, represented by detection of tau, but not GFP in the brain. We also found that tau trafficking was attenuated upon inhibition of the endocytic factor dynamin or the kinase glycogen synthase kinase-3ß ( GSK-3ß ). Further work revealed that dynamin promotes tau uptake in recipient tissues, whereas GSK-3ß appears to promote tau spread via direct phosphorylation of tau. Our robust and flexible system will promote the identification of tau trafficking components involved in the pathogenesis of neurodegenerative diseases. SUMMARY STATEMENT: The trafficking of toxic proteins in neurodegenerative disease is well-known but poorly understood. Our model will allow rapid and new insight into molecular mechanisms underlying this process.

Glucocerebrosidase deficiency leads to neuropathology via cellular immune activation.

Mutations in GBA (glucosylceramidase beta), which encodes the lysosomal enzyme glucocerebrosidase (GCase), are the strongest genetic risk factor for the neurodegenerative disorders Parkinson's disease (PD) and Lewy body dementia. Recent work has suggested that neuroinflammation may be an important factor in the risk conferred by GBA mutations. We therefore systematically tested the contributions of immune-related genes to neuropathology in a Drosophila model of GCase deficiency. We identified target immune factors via RNA-Seq and proteomics on heads from GCase-deficient flies, which revealed both increased abundance of humoral factors and increased macrophage activation. We then manipulated the identified immune factors and measured their effect on head protein aggregates, a hallmark of neurodegenerative disease. Genetic ablation of humoral (secreted) immune factors did not suppress the development of protein aggregation. By contrast, re-expressing Gba1b in activated macrophages suppressed head protein aggregation in Gba1b mutants and rescued their lifespan and behavioral deficits. Moreover, reducing the GCase substrate glucosylceramide in activated macrophages also ameliorated Gba1b mutant phenotypes. Taken together, our findings show that glucosylceramide accumulation due to GCase deficiency leads to macrophage activation, which in turn promotes the development of neuropathology.

Study protocol for the Multiple Symptoms Study 3: a pragmatic, randomised controlled trial of a clinic for patients with persistent (medically unexplained) physical symptoms.

INTRODUCTION: Persistent physical symptoms (which cannot be adequately attributed to physical disease) affect around 1 million people (2% of adults) in the UK. They affect patients' quality of life and account for at least one third of referrals from General Practitioners (GPs) to specialists. These referrals give patients little benefit but have a real cost to health services time and diagnostic resources. The symptoms clinic has been designed to help people make sense of persistent physical symptoms (especially if medical tests have been negative) and to reduce the impact of symptoms on daily life. METHODS AND ANALYSIS: This pragmatic, multicentre, randomised controlled trial will assess the clinical and cost-effectiveness of the symptoms clinic intervention plus usual care compared with usual care alone. Patients were identified through GP searches and mail-outs and recruited by the central research team. 354 participants were recruited and individually randomised (1:1). The primary outcome is the self-reported Physical Health Questionnaire-15 at 52 weeks postrandomisation. Secondary outcome measures include the EuroQol 5 dimension 5 level and healthcare resource use. Outcome measures will also be collected at 13 and 26 weeks postrandomisation. A process evaluation will be conducted including consultation content analysis and interviews with participants and key stakeholders. ETHICS AND DISSEMINATION: Ethics approval has been obtained via Greater Manchester Central Research Ethics Committee (Reference 18/NW/0422). The results of the trial will be submitted for publication in peer-reviewed journals, presented at relevant conferences and disseminated to trial participants and patient interest groups. TRIAL REGISTRATION NUMBER: ISRCTN57050216.

Shockwave Lithotripsy Versus Ureteroscopic Treatment as Therapeutic Interventions for Stones of the Ureter (TISU): A Multicentre Randomised Controlled Non-inferiority Trial.

BACKGROUND: Renal stone disease is common and can cause emergency presentation with acute pain due to ureteric colic. International guidelines have stated the need for a multicentre randomised controlled trial (RCT) to determine whether a non-invasive outpatient (shockwave lithotripsy [SWL]) or surgical (ureteroscopy [URS]) intervention should be the first-line treatment for those needing active intervention. This has implications for shaping clinical pathways. OBJECTIVE: To report a pragmatic multicentre non-inferiority RCT comparing SWL with URS. DESIGN, SETTING, AND PARTICIPANTS: This trial tested for non-inferiority of up to two sessions of SWL compared with URS as initial treatment for ureteric stones requiring intervention. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was whether further intervention was required to clear the stone, and secondary outcomes included quality of life assessment, severity of pain, and serious complications; these were based on questionnaires at baseline, 8 wk, and 6 mo. We included patients over 16 yr with a single ureteric stone clinically deemed to require intervention. Intention-to-treat and per-protocol analyses were planned. RESULTS AND LIMITATIONS: The study recruited between July 1, 2013 and June 30, 2017. We recruited 613 participants from a total of 1291 eligible patients, randomising 306 to SWL and 307 to URS. Sixty-seven patients (22.1%) in the SWL arm needed further treatment compared with 31 patients (10.3%) in the URS arm. The absolute risk difference was 11.7% (95% confidence interval 5.6%, 17.8%) in favour of URS, which was inside the 20% threshold we set for demonstrating noninferiority of SWL. CONCLUSIONS: This RCT was designed to test whether SWL is non-inferior to URS and confirmed this; although SWL is an outpatient noninvasive treatment with potential advantages both for patients and for reducing the use of inpatient health care resources, the trial showed a benefit in overall clinical outcomes with URS compared with SWL, reflecting contemporary practice. The Therapeutic Interventions for Stones of the Ureter (TISU) study provides new evidence to help guide the choice of modality for this common health condition. PATIENT SUMMARY: We present the largest trial comparing ureteroscopy versus extracorporeal shockwave lithotripsy for ureteric stones. While ureteroscopy had marginally improved outcome in terms of stone clearance, as expected, shockwave lithotripsy had better results in terms of health care costs. These results should enable patients and health care providers to optimise treatment pathways for this common urological condition.

Glucocerebrosidase reduces the spread of protein aggregation in a Drosophila melanogaster model of neurodegeneration by regulating proteins trafficked by extracellular vesicles.

Abnormal protein aggregation within neurons is a key pathologic feature of Parkinson's disease (PD). The spread of brain protein aggregates is associated with clinical disease progression, but how this occurs remains unclear. Mutations in glucosidase, beta acid 1 (GBA), which encodes glucocerebrosidase (GCase), are the most penetrant common genetic risk factor for PD and dementia with Lewy bodies and associate with faster disease progression. To explore how GBA mutations influence pathogenesis, we previously created a Drosophila model of GBA deficiency (Gba1b) that manifests neurodegeneration and accelerated protein aggregation. Proteomic analysis of Gba1b mutants revealed dysregulation of proteins involved in extracellular vesicle (EV) biology, and we found altered protein composition of EVs from Gba1b mutants. Accordingly, we hypothesized that GBA may influence pathogenic protein aggregate spread via EVs. We found that accumulation of ubiquitinated proteins and Ref(2)P, Drosophila homologue of mammalian p62, were reduced in muscle and brain tissue of Gba1b flies by ectopic expression of wildtype GCase in muscle. Neuronal GCase expression also rescued protein aggregation both cell-autonomously in brain and non-cell-autonomously in muscle. Muscle-specific GBA expression reduced the elevated levels of EV-intrinsic proteins and Ref(2)P found in EVs from Gba1b flies. Perturbing EV biogenesis through neutral sphingomyelinase (nSMase), an enzyme important for EV release and ceramide metabolism, enhanced protein aggregation when knocked down in muscle, but did not modify Gba1b mutant protein aggregation when knocked down in neurons. Lipidomic analysis of nSMase knockdown on ceramide and glucosylceramide levels suggested that Gba1b mutant protein aggregation may depend on relative depletion of specific ceramide species often enriched in EVs. Finally, we identified ectopically expressed GCase within isolated EVs. Together, our findings suggest that GCase deficiency promotes accelerated protein aggregate spread between cells and tissues via dysregulated EVs, and EV-mediated trafficking of GCase may partially account for the reduction in aggregate spread.

Slowed Protein Turnover in Aging Drosophila Reflects a Shift in Cellular Priorities.

The accumulation of protein aggregates and dysfunctional organelles as organisms age has led to the hypothesis that aging involves general breakdown of protein quality control. We tested this hypothesis using a proteomic and informatic approach in the fruit fly Drosophila melanogaster. Turnover of most proteins was markedly slower in old flies. However, ribosomal and proteasomal proteins maintained high turnover rates, suggesting that the observed slowdowns in protein turnover might not be due to a global failure of quality control. As protein turnover reflects the balance of protein synthesis and degradation, we investigated whether decreases in synthesis or decreases in degradation would best explain the observed slowdowns in protein turnover. We found that while many individual proteins in old flies showed slower turnover due to decreased degradation, an approximately equal number showed slower turnover due to decreased synthesis, and enrichment analyses revealed that translation machinery itself was less abundant. Mitochondrial complex I subunits and glycolytic enzymes were decreased in abundance as well, and proteins involved in glutamine-dependent anaplerosis were increased, suggesting that old flies modify energy production to limit oxidative damage. Together, our findings suggest that age-related proteostasis changes in Drosophila represent a coordinated adaptation rather than a system collapse.

Autophagy accounts for approximately one-third of mitochondrial protein turnover and is protein selective.

The destruction of mitochondria through macroautophagy (autophagy) has been recognised as a major route of mitochondrial protein degradation since its discovery more than 50 years ago, but fundamental questions remain unanswered. First, how much mitochondrial protein turnover occurs through auto-phagy? Mitochondrial proteins are also degraded by nonautophagic mechanisms, and the proportion of mitochondrial protein turnover that occurs through autophagy is still unknown. Second, does auto-phagy degrade mitochondrial proteins uniformly or selectively? Autophagy was originally thought to degrade all mitochondrial proteins at the same rate, but recent work suggests that mitochondrial autophagy may be protein selective. To investigate these questions, we used a proteomics-based approach in the fruit fly Drosophila melanogaster, comparing mitochondrial protein turnover rates in autophagy-deficient Atg7 mutants and controls. We found that ~35% of mitochondrial protein turnover occurred via autophagy. Similar analyses using parkin mutants revealed that parkin-dependent mitophagy accounted for ~25% of mitochondrial protein turnover, suggesting that most mitochondrial autophagy specifically eliminates dysfunctional mitochondria. We also found that our results were incompatible with uniform autophagic turnover of mitochondrial proteins and consistent with protein-selective autophagy. In particular, the autophagic turnover rates of individual mitochondrial proteins varied widely, and only a small amount of the variation could be attributed to tissue differences in mitochondrial composition and autophagy rate. Furthermore, analyses comparing autophagy-deficient and control human fibroblasts revealed diverse autophagy-dependent turnover rates even in homogeneous cells. In summary, our work indicates that autophagy acts selectively on mitochondrial proteins, and that most mitochondrial protein turnover occurs through non-autophagic processes. Abbreviations:Atg5: Autophagy-related 5 (Drosophila); ATG5: autophagy related 5 (human); Atg7: Autophagy-related 7 (Drosophila); ATG7: autophagy related 7 (human); DNA: deoxyribonucleic acid; ER: endoplasmic reticulum; GFP: green fluorescent protein; MS: mass spectrometry; park: parkin (Drosophila); Pink1: PTEN-induced putative kinase 1 (Drosophila); PINK1: PTEN-induced kinase 1 (human); PRKN: parkin RBR E3 ubiquitin protein ligase (human); RNA: ribonucleic acid; SD: standard deviation; Ub: ubiquitin/ubiquitinated; WT: wild-type; YME1L: YME1 like ATPase (Drosophila); YME1L1: YME1 like 1 ATPase (human).

Lon protease inactivation in Drosophila causes unfolded protein stress and inhibition of mitochondrial translation.

Mitochondrial dysfunction is a frequent participant in common diseases and a principal suspect in aging. To combat mitochondrial dysfunction, eukaryotes have evolved a large repertoire of quality control mechanisms. One such mechanism involves the selective degradation of damaged or misfolded mitochondrial proteins by mitochondrial resident proteases, including proteases of the ATPase Associated with diverse cellular Activities (AAA+) family. The importance of the AAA+ family of mitochondrial proteases is exemplified by the fact that mutations that impair their functions cause a variety of human diseases, yet our knowledge of the cellular responses to their inactivation is limited. To address this matter, we created and characterized flies with complete or partial inactivation of the Drosophila matrix-localized AAA+ protease Lon. We found that a Lon null allele confers early larval lethality and that severely reducing Lon expression using RNAi results in shortened lifespan, locomotor impairment, and respiratory defects specific to respiratory chain complexes that contain mitochondrially encoded subunits. The respiratory chain defects of Lon knockdown (Lon KD ) flies appeared to result from severely reduced translation of mitochondrially encoded genes. This translational defect was not a consequence of reduced mitochondrial transcription, as evidenced by the fact that mitochondrial transcripts were elevated in abundance in Lon KD flies. Rather, the translational defect of Lon KD flies appeared to be derived from sequestration of mitochondrially encoded transcripts in highly dense ribonucleoparticles. The translational defect of Lon KD flies was also accompanied by a substantial increase in unfolded mitochondrial proteins. Together, our findings suggest that the accumulation of unfolded mitochondrial proteins triggers a stress response that culminates in the inhibition of mitochondrial translation. Our work provides a foundation to explore the underlying molecular mechanisms.

Glucocerebrosidase deficiency promotes protein aggregation through dysregulation of extracellular vesicles.

Mutations in the glucosylceramidase beta (GBA) gene are strongly associated with neurodegenerative diseases marked by protein aggregation. GBA encodes the lysosomal enzyme glucocerebrosidase, which breaks down glucosylceramide. A common explanation for the link between GBA mutations and protein aggregation is that lysosomal accumulation of glucosylceramide causes impaired autophagy. We tested this hypothesis directly by measuring protein turnover and abundance in Drosophila mutants with deletions in the GBA ortholog Gba1b. Proteomic analyses revealed that known autophagy substrates, which had severely impaired turnover in autophagy-deficient Atg7 mutants, showed little to no overall slowing of turnover or increase in abundance in Gba1b mutants. Likewise, Gba1b mutants did not have the marked impairment of mitochondrial protein turnover seen in mitophagy-deficient parkin mutants. Proteasome activity, microautophagy, and endocytic degradation also appeared unaffected in Gba1b mutants. However, we found striking changes in the turnover and abundance of proteins associated with extracellular vesicles (EVs), which have been proposed as vehicles for the spread of protein aggregates in neurodegenerative disease. These changes were specific to Gba1b mutants and did not represent an acceleration of normal aging. Western blotting of isolated EVs confirmed the increased abundance of EV proteins in Gba1b mutants, and nanoparticle tracking analysis revealed that Gba1b mutants had six times as many EVs as controls. Genetic perturbations of EV production in Gba1b mutants suppressed protein aggregation, demonstrating that the increase in EV abundance contributed to the accumulation of protein aggregates. Together, our findings indicate that glucocerebrosidase deficiency causes pathogenic changes in EV metabolism and may promote the spread of protein aggregates through extracellular vesicles.

Loss of the Drosophila m-AAA mitochondrial protease paraplegin results in mitochondrial dysfunction, shortened lifespan, and neuronal and muscular degeneration.

The progressive accumulation of dysfunctional mitochondria is implicated in aging and in common diseases of the elderly. To oppose this occurrence, organisms employ a variety of strategies, including the selective degradation of oxidatively damaged and misfolded mitochondrial proteins. Genetic studies in yeast indicate that the ATPase Associated with diverse cellular Activities (AAA+) family of mitochondrial proteases account for a substantial fraction of this protein degradation, but their metazoan counterparts have been little studied, despite the fact that mutations in the genes encoding these proteases cause a variety of human diseases. To begin to explore the biological roles of the metazoan mitochondrial AAA+ protease family, we have created a CRISPR/Cas9 allele of the Drosophila homolog of SPG7, which encodes an inner membrane-localized AAA+ protease known as paraplegin. Drosophila SPG7 mutants exhibited shortened lifespan, progressive locomotor defects, sensitivity to chemical and environmental stress, and muscular and neuronal degeneration. Ultrastructural examination of photoreceptor neurons indicated that the neurodegenerative phenotype of SPG7 mutants initiates at the synaptic terminal. A variety of mitochondrial defects accompanied the degenerative phenotypes of SPG7 mutants, including altered axonal transport of mitochondria, accumulation of electron-dense material in the matrix of flight muscle mitochondria, reduced activities of respiratory chain complexes I and II, and severely swollen and dysmorphic mitochondria in the synaptic terminals of photoreceptors. Drosophila SPG7 mutants recapitulate key features of human diseases caused by mutations in SPG7, and thus provide a foundation for the identification of Drosophila paraplegin substrates and strategies that could be used to ameliorate the symptoms of these diseases.

Glucocerebrosidase Deficiency in Drosophila Results in α-Synuclein-Independent Protein Aggregation and Neurodegeneration.

Mutations in the glucosidase, beta, acid (GBA1) gene cause Gaucher's disease, and are the most common genetic risk factor for Parkinson's disease (PD) and dementia with Lewy bodies (DLB) excluding variants of low penetrance. Because α-synuclein-containing neuronal aggregates are a defining feature of PD and DLB, it is widely believed that mutations in GBA1 act by enhancing α-synuclein toxicity. To explore this hypothesis, we deleted the Drosophila GBA1 homolog, dGBA1b, and compared the phenotypes of dGBA1b mutants in the presence and absence of α-synuclein expression. Homozygous dGBA1b mutants exhibit shortened lifespan, locomotor and memory deficits, neurodegeneration, and dramatically increased accumulation of ubiquitinated protein aggregates that are normally degraded through an autophagic mechanism. Ectopic expression of human α-synuclein in dGBA1b mutants resulted in a mild enhancement of dopaminergic neuron loss and increased α-synuclein aggregation relative to controls. However, α-synuclein expression did not substantially enhance other dGBA1b mutant phenotypes. Our findings indicate that dGBA1b plays an important role in the metabolism of protein aggregates, but that the deleterious consequences of mutations in dGBA1b are largely independent of α-synuclein. Future work with dGBA1b mutants should reveal the mechanism by which mutations in dGBA1b lead to accumulation of protein aggregates, and the potential influence of this protein aggregation on neuronal integrity.

PINK1-Parkin pathway activity is regulated by degradation of PINK1 in the mitochondrial matrix.

Loss-of-function mutations in PINK1, which encodes a mitochondrially targeted serine/threonine kinase, result in an early-onset heritable form of Parkinson's disease. Previous work has shown that PINK1 is constitutively degraded in healthy cells, but selectively accumulates on the surface of depolarized mitochondria, thereby initiating their autophagic degradation. Although PINK1 is known to be a cleavage target of several mitochondrial proteases, whether these proteases account for the constitutive degradation of PINK1 in healthy mitochondria remains unclear. To explore the mechanism by which PINK1 is degraded, we performed a screen for mitochondrial proteases that influence PINK1 abundance in the fruit fly Drosophila melanogaster. We found that genetic perturbations targeting the matrix-localized protease Lon caused dramatic accumulation of processed PINK1 species in several mitochondrial compartments, including the matrix. Knockdown of Lon did not decrease mitochondrial membrane potential or trigger activation of the mitochondrial unfolded protein stress response (UPRmt), indicating that PINK1 accumulation in Lon-deficient animals is not a secondary consequence of mitochondrial depolarization or the UPRmt. Moreover, the influence of Lon on PINK1 abundance was highly specific, as Lon inactivation had little or no effect on the abundance of other mitochondrial proteins. Further studies indicated that the processed forms of PINK1 that accumulate upon Lon inactivation are capable of activating the PINK1-Parkin pathway in vivo. Our findings thus suggest that Lon plays an essential role in regulating the PINK1-Parkin pathway by promoting the degradation of PINK1 in the matrix of healthy mitochondria.

VCP is essential for mitochondrial quality control by PINK1/Parkin and this function is impaired by VCP mutations.

Mutations in VCP cause multisystem degeneration impacting the nervous system, muscle, and/or bone. Patients may present with ALS, Parkinsonism, frontotemporal dementia, myopathy, Paget's disease, or a combination of these. The disease mechanism is unknown. We developed a Drosophila model of VCP mutation-dependent degeneration. The phenotype is reminiscent of PINK1 and parkin mutants, including a pronounced mitochondrial defect. Indeed, VCP interacts genetically with the PINK1/parkin pathway in vivo. Paradoxically, VCP complements PINK1 deficiency but not parkin deficiency. The basis of this paradox is resolved by mechanistic studies in vitro showing that VCP recruitment to damaged mitochondria requires Parkin-mediated ubiquitination of mitochondrial targets. VCP recruitment coincides temporally with mitochondrial fission, and VCP is required for proteasome-dependent degradation of Mitofusins in vitro and in vivo. Further, VCP and its adaptor Npl4/Ufd1 are required for clearance of damaged mitochondria via the PINK1/Parkin pathway, and this is impaired by pathogenic mutations in VCP.

The PINK1-Parkin pathway promotes both mitophagy and selective respiratory chain turnover in vivo.

The accumulation of damaged mitochondria has been proposed as a key factor in aging and the pathogenesis of many common age-related diseases, including Parkinson disease (PD). Recently, in vitro studies of the PD-related proteins Parkin and PINK1 have found that these factors act in a common pathway to promote the selective autophagic degradation of damaged mitochondria (mitophagy). However, whether Parkin and PINK1 promote mitophagy under normal physiological conditions in vivo is unknown. To address this question, we used a proteomic approach in Drosophila to compare the rates of mitochondrial protein turnover in parkin mutants, PINK1 mutants, and control flies. We found that parkin null mutants showed a significant overall slowing of mitochondrial protein turnover, similar to but less severe than the slowing seen in autophagy-deficient Atg7 mutants, consistent with the model that Parkin acts upstream of Atg7 to promote mitophagy. By contrast, the turnover of many mitochondrial respiratory chain (RC) subunits showed greater impairment in parkin than Atg7 mutants, and RC turnover was also selectively impaired in PINK1 mutants. Our findings show that the PINK1-Parkin pathway promotes mitophagy in vivo and, unexpectedly, also promotes selective turnover of mitochondrial RC subunits. Failure to degrade damaged RC proteins could account for the RC deficits seen in many PD patients and may play an important role in PD pathogenesis.

Surveillance mammography for detecting ipsilateral breast tumour recurrence and metachronous contralateral breast cancer: a systematic review.

OBJECTIVES: To determine the diagnostic accuracy of surveillance mammography for detecting ipsilateral breast tumour recurrence and metachronous contralateral breast cancer in women previously treated for primary breast cancer. METHODS: A systematic review of surveillance mammography compared with ultrasound, magnetic resonance imaging (MRI), specialist-led clinical examination or unstructured primary care follow-up, using histopathological assessment for test positives and follow-up for test negatives as the reference standard. RESULTS: Nine studies met our inclusion criteria. Variations in study comparisons precluded meta-analysis. For routine ipsilateral breast tumour detection, surveillance mammography sensitivity ranged from 64-67% and specificity ranged from 85-97%. For MRI, sensitivity ranged from 86-100% and specificity was 93%. For non-routine ipsilateral breast tumour detection, sensitivity and specificity for surveillance mammography ranged from 50-83% and 57-75% and for MRI 93-100% and 88-96%. For routine metachronous contralateral breast cancer detection, one study reported sensitivity of 67% and specificity of 50% for both surveillance mammography and MRI. CONCLUSION: Although mammography is associated with high sensitivity and specificity, MRI is the most accurate test for detecting ipsilateral breast tumour recurrence and metachronous contralateral breast cancer in women previously treated for primary breast cancer. Results should be interpreted with caution because of the limited evidence base. Key Points • Surveillance mammography is associated with high sensitivity and specificity • Findings suggest that MRI is the most accurate test for detecting further breast cancer • Robust conclusions cannot be made due to the limited evidence base • Further research comparing surveillance mammography and other diagnostic tests is required.

Using the theory of planned behaviour as a process evaluation tool in randomised trials of knowledge translation strategies: A case study from UK primary care.

BACKGROUND: Randomised trials of knowledge translation strategies for professional behaviour change can provide robust estimates of effectiveness, but offer little insight into the causal mechanisms by which any change is produced. To illustrate the applicability of causal methods within randomised trials, we undertook a theory-based process evaluation study within an implementation trial to explore whether the cognitions of primary care doctors' predicted their test requesting behaviours and, secondly, whether the trial results were mediated by the theoretical constructs. METHODS: The process evaluation comprised a cross-sectional questionnaire survey of a random 50% sample of the randomised groups of primary care practices in Grampian (NHS Grampian), UK, who took part in a trial of the effect of enhanced feedback and brief educational reminders on test requesting behaviour. The process evaluation was based upon the Theory of Planned Behaviour and focussed on three of the test requesting behaviours that were targeted in the trial -- ferritin, follicle stimulating hormone (FSH), and Helicobacter Pylori serology (HPS). RESULTS: The questionnaire was completed by 131 primary care doctors (56%) from 42 (98%) of the sampled practices. Behavioural intention, attitude, and subjective norm were highly correlated for all the tests. There was no evidence that perceived behavioural control was correlated with any of the other measures. Simple linear regression analysis of the rate of test requests on minimum behavioural intentions had R2 of 11.1%, 12.5%, and 0.1% for ferritin, FSH, and HPS requesting, respectively. Mediational analysis showed that the trial results for ferritin and FSH were partially mediated (between 23% and 78% mediation) through intentions. The HPS trial result was not mediated through intention. CONCLUSIONS: This study demonstrated that a theory-based process evaluation can provide useful information on causal mechanisms that aid not only interpretation of the trial but also inform future evaluations and intervention development.

The mitochondrial fusion-promoting factor mitofusin is a substrate of the PINK1/parkin pathway.

Loss-of-function mutations in the PINK1 or parkin genes result in recessive heritable forms of parkinsonism. Genetic studies of Drosophila orthologs of PINK1 and parkin indicate that PINK1, a mitochondrially targeted serine/threonine kinase, acts upstream of Parkin, a cytosolic ubiquitin-protein ligase, to promote mitochondrial fragmentation, although the molecular mechanisms by which the PINK1/Parkin pathway promotes mitochondrial fragmentation are unknown. We tested the hypothesis that PINK1 and Parkin promote mitochondrial fragmentation by targeting core components of the mitochondrial morphogenesis machinery for ubiquitination. We report that the steady-state abundance of the mitochondrial fusion-promoting factor Mitofusin (dMfn) is inversely correlated with the activity of PINK1 and Parkin in Drosophila. We further report that dMfn is ubiquitinated in a PINK1- and Parkin-dependent fashion and that dMfn co-immunoprecipitates with Parkin. By contrast, perturbations of PINK1 or Parkin did not influence the steady-state abundance of the mitochondrial fission-promoting factor Drp1 or the mitochondrial fusion-promoting factor Opa1, or the subcellular distribution of Drp1. Our findings suggest that dMfn is a direct substrate of the PINK1/Parkin pathway and that the mitochondrial morphological alterations and tissue degeneration phenotypes that derive from mutations in PINK1 and parkin result at least in part from reduced ubiquitin-mediated turnover of dMfn.

The PINK1/Parkin pathway regulates mitochondrial morphology.

Loss-of-function mutations in the PTEN-induced kinase 1 (PINK1) or parkin genes, which encode a mitochondrially localized serine/threonine kinase and a ubiquitin-protein ligase, respectively, result in recessive familial forms of Parkinsonism. Genetic studies in Drosophila indicate that PINK1 acts upstream of Parkin in a common pathway that influences mitochondrial integrity in a subset of tissues, including flight muscle and dopaminergic neurons. The mechanism by which PINK1 and Parkin influence mitochondrial integrity is currently unknown, although mutations in the PINK1 and parkin genes result in enlarged or swollen mitochondria, suggesting a possible regulatory role for the PINK1/Parkin pathway in mitochondrial morphology. To address this hypothesis, we examined the influence of genetic alterations affecting the machinery that governs mitochondrial morphology on the PINK1 and parkin mutant phenotypes. We report that heterozygous loss-of-function mutations of drp1, which encodes a key mitochondrial fission-promoting component, are largely lethal in a PINK1 or parkin mutant background. Conversely, the flight muscle degeneration and mitochondrial morphological alterations that result from mutations in PINK1 and parkin are strongly suppressed by increased drp1 gene dosage and by heterozygous loss-of-function mutations affecting the mitochondrial fusion-promoting factors OPA1 and Mfn2. Finally, we find that an eye phenotype associated with increased PINK1/Parkin pathway activity is suppressed by perturbations that reduce mitochondrial fission and enhanced by perturbations that reduce mitochondrial fusion. Our studies suggest that the PINK1/Parkin pathway promotes mitochondrial fission and that the loss of mitochondrial and tissue integrity in PINK1 and parkin mutants derives from reduced mitochondrial fission.

Effect of enhanced feedback and brief educational reminder messages on laboratory test requesting in primary care: a cluster randomised trial.

BACKGROUND: Laboratory services play an important part in screening, diagnosis, and management of patients within primary care. However, unnecessary use of laboratory tests is increasing. Our aim was to assess the effect of two interventions on the number of laboratory tests requested by primary-care physicians. METHODS: We did a cluster randomised controlled trial using a 2x2 factorial design, involving 85 primary-care practices (370 family practitioners) that request all laboratory tests from one regional centre. The interventions were quarterly feedback of practice requesting rates for nine laboratory tests, enhanced with educational messages, and brief educational reminder messages added to the test result reports for nine laboratory tests. The primary outcome was the number of targeted tests requested by primary-care practices during the 12 months of the intervention. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN06490422. FINDINGS: Practices that received either or both the enhanced feedback and the reminder messages were significantly less likely than the control group to request the targeted tests in total (enhanced feedback odds ratio 0.87, 95% CI 0.81-0.94; reminder messages 0.89, 0.83-0.93). The effect of the interventions varied across the targeted tests individually, although the number of tests requested for both interventions was generally reduced. Neither intervention was consistently better than the other. INTERPRETATION: Enhanced feedback of requesting rates and brief educational reminder messages, alone and in combination, are effective strategies for reducing test requesting in primary care. Both strategies are feasible within most laboratory settings.