Early but reversible haemostatic changes in a-symptomatic females expressing COVID-19 antibodies.

The coronavirus, COVID-19 pandemic spread across the globe in 2020, with an initial high case mortality in those requiring intensive care treatment due to serious complication. A vaccine programme was quickly developed and currently the UK is one of highest double vaccinated and boosted countries in the world. Despite tremendous efforts by the UK, new cases of COVID-19 are still occurring, due to viral mutation. A major problem associated with COVID-19 is the large a-symptomatic spread within the population. Little investigation into the a-symptomatic population has been carried out and therefore we pose that the residual effects of a-symptomatic infection is still largely unknown. Prior to mass vaccination, a multi-phased single cohort study of IgM and IgG COVID-19 antibody prevalence and the associated haemostatic changes were assessed in a Welsh cohort of 739 participants, at three time points. Positive antibody participants with age and gender matched negative antibody controls were assessed at 0, 3 and 6 months. Antibody positive females appeared to have lower antibody responses in comparison to their a-symptomatic male counterparts. Despite this initial testing showed a unique significant increase in TRAP-6-induced platelet aggregation, prothrombin time (PT) and clot initiation time. Despite coagulation parameters beginning to return to normal at 3 months, significant decreases are observed in both haemoglobin and haematocrit levels. The production of extracellular vesicles (EV) was also determined in this study. Although the overall number of EV does not change throughout the study, at the initial 0 months' time point a significant increase in the percentage of circulating pro-coagulant platelet derived EV is seen, which does not appear to be related to the extent of platelet activation in the subject. We conclude that early, but reversible changes in haemostatic pathways within the a-symptomatic, female, antibody positive COVID-19 individuals are present. These changes may be key in identifying a period of pro-coagulative risk for a-symptomatic female patients.

Ventricular tachycardia and raised troponin: "What if it's a pheochromocytoma"? Some lessons from a crisis.

A 63-year-old female with cardiovascular risk factors presented with tremor, sweating, lower back discomfort, nausea and dyspnoea. Electrocardiogram showed sinus tachycardia with lateral ST-depression. High-sensitivity troponin-T was dynamically elevated (72ng/L to 112ng/L on one-hour repeat). Overnight, there was an episode of ventricular tachycardia with further troponin rise to 364ng/L. Coronary angiogram demonstrated non-obstructive coronary artery disease. Post-procedure, the patient developed a hypertensive crisis with pulmonary oedema (invasive blood pressure 350/140mmHg). This was managed with intravenous phentolamine. Ondansetron and metoclopramide were given for intractable vomiting. A pheochromocytoma was subsequently confirmed and surgically excised. Our experience in this case generated several important learning points that we hope may be of benefit to others who encounter suspected pheochromocytomas on the acute medical take.

A systematic review of psychological training or interventions given to UK military personnel prior to deployment.

INTRODUCTION: Predeployment stress management/mental health training is routinely delivered in an effort to mitigate potential adverse psychological effects. Little is known about the effectiveness of such interventions. METHODS: A systematic literature review explored research outcomes related to this subject, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines. An electronic database search using key terms identified studies published between January 2007 and March 2019. Comprehensive inclusion/exclusion criteria were applied and study quality was appraised by two reviewers using 12 criteria adapted from the Critical Appraisal Skills Programme (CASP) checklist. Papers were excluded if they were allocated CASP scores ≤10 out of 24. RESULTS: 2003 references were identified; 15 papers fulfilled inclusion criteria and quality threshold requirements. Included studies were randomised controlled trial design (n=8), quasi-experimental (n=5), case report (n=1) and cross-sectional (n=1). Duration of follow-up assessment varied from immediately postintervention to 24 months. The included studies were heterogeneous so clear recommendations relating to predeployment training for military personnel could not be made. Although somewhat disparate, predeployment interventions shared the aim of promoting prior to, during and after deployment health and well-being. Social benefits such as improved cohesion and improved stress management skills were identified in some studies, although substantial mental health and well-being benefits were not found. CONCLUSIONS: Evidence for the effectiveness of predeployment psychological interventions is scant. Every attempt should be made to use methods and measures to facilitate comparisons across studies, to attempt a longer follow-up timescale and to clarify key trainer characteristics.

Spinal Stenosis in Familial Transthyretin Amyloidosis.

Here we describe a patient with genetically confirmed ATTR, a family history of the disease and histological confirmation following carpal tunnel release surgery but no other manifestations. The first major neurological or systemic manifestation was cauda equina syndrome with ATTR deposits contributing to lumbar spinal stenosis. Recent gene therapy trials showed improvement in the neuropathy in TTR amyloidosis. This case highlights the need for awareness of the heterogeneous neurological phenotype seen in ATTR to aid earlier diagnosis especially now that disease modifying therapies are available.

The impact of a structured clinical training course on interns' self-reported confidence with core clinical urology skills.

BACKGROUND: Undergraduate training in core urology skills is lacking in many Irish training programmes. AIMS: Our aim was to assess newly qualified doctors' experience and confidence with core urological competencies. METHODS: A questionnaire survey covering exposure to urology and confidence with core clinical skills was circulated to all candidates. The group then attended a skills course covering male/female catheterisation, insertion of three-way catheters, bladder irrigation and management of long-term suprapubic catheters. The groups were re-surveyed following the course. RESULTS: Forty-five interns completed the pre-course questionnaire (group 1) and 27 interns completed the post-course questionnaire (group 2). 24/45 (53%) had no experience of catheter insertion on a patient during their undergraduate training. 26/45 (58%) were unsupervised during their first catheter insertion. 12/45 (27%) had inserted a female catheter. 18/45 (40%) had inserted a three-way catheter. 12/45 (27%) had changed a suprapubic catheter. 40/45 (89%) in group 1 reported 'good' or 'excellent' confidence with male urinary catheterisation, compared to 25/27 (92.5%) in group 2. 18/45 (40%) in group 1 reported 'none' or 'poor' confidence with female catheterisation, compared to 7/27 (26%) in group 2. 22/45 (49%) in group 1 reported 'none' or 'poor' confidence with insertion of three-way catheters, compared to 2/27 (7%) in group 2. 32/45 (71%) in group 1 reported 'none' or 'poor' confidence in changing long-term suprapubic catheters, falling to 3/27 (11%) in group 2. CONCLUSION: This study raises concerns about newly qualified doctors' practical experience in urology. We suggest that this course improves knowledge and confidence with practical urology skills and should be incorporated into intern induction.

Potassium channel gene associations with joint processing speed and white matter impairments in schizophrenia.

Patients with schizophrenia show decreased processing speed on neuropsychological testing and decreased white matter integrity as measured by diffusion tensor imaging, two traits shown to be both heritable and genetically associated indicating that there may be genes that influence both traits as well as schizophrenia disease risk. The potassium channel gene family is a reasonable candidate to harbor such a gene given the prominent role potassium channels play in the central nervous system in signal transduction, particularly in myelinated axons. We genotyped members of the large potassium channel gene family focusing on putatively functional single nucleotide polymorphisms (SNPs) in a population of 363 controls, 194 patients with schizophrenia spectrum disorder (SSD) and 28 patients with affective disorders with psychotic features who completed imaging and neuropsychological testing. We then performed three association analyses using three phenotypes - processing speed, whole-brain white matter fractional anisotropy (FA) and schizophrenia spectrum diagnosis. We extracted SNPs showing an association at a nominal P value of <0.05 with all three phenotypes in the expected direction: decreased processing speed, decreased FA and increased risk of SSD. A single SNP, rs8234, in the 3' untranslated region of voltage-gated potassium channel subfamily Q member 1 (KCNQ1) was identified. Rs8234 has been shown to affect KCNQ1 expression levels, and KCNQ1 levels have been shown to affect neuronal action potentials. This exploratory analysis provides preliminary data suggesting that KCNQ1 may contribute to the shared risk for diminished processing speed, diminished white mater integrity and increased risk of schizophrenia.

A study of the neuropathy associated with transthyretin amyloidosis (ATTR) in the UK.

BACKGROUND: Hereditary transthyretin amyloidosis (ATTR) is usually characterised by a progressive peripheral and autonomic neuropathy often with associated cardiac failure and is due to dominantly inherited transthyretin mutations causing accelerated amyloid deposition. The UK population is unique in that the majority of patients have the T60A missense mutation in ATTR where tyrosine is replaced by adenine at position 60. This has been traced to a single founder mutation from north-west Ireland. The neuropathy phenotype is less well described than the cardiac manifestations in this group. METHODS: We present the findings from an observational cohort study of patients with ATTR attending the National Hospital Inherited Neuropathy Clinic between 2009 and 2013. Detailed clinical neurological and electrophysiological data were collected on all patients alongside correlating autonomic and cardiac assessments. Follow-up data were available on a subset. RESULTS: Forty-four patients with genetically confirmed ATTR were assessed; 37 were symptomatic; mean age at onset=62 years, range=38-75 years; 75.7% male. T60A was the most common mutation (17/37), followed by V30M (5/37). A severe, rapidly progressive, predominantly length dependent axonal sensorimotor neuropathy was the predominant phenotype. T60A patients were distinguished by earlier and more frequent association with carpal tunnel syndrome; a predominance of negative sensory symptoms at onset; significant vibration deficits; and a non-length dependent progression of motor deficit. Progression of the neuropathy was observed over a relatively short follow-up period (2 years) in 20 patients with evidence of clinically measurable annual change in Medical Research Council (MRC) sum score (-1.5 points per year) and Charcot Marie Tooth Neuropathy Score (CMTNS:2.7 points per year), and a congruent trend in the electrophysiological measures used. CONCLUSION: The description of the ATTR neuropathy phenotype, especially in the T60A patients, should aid early diagnosis as well as contribute to the understanding of its natural history.

Transthyretin V122I amyloidosis with clinical and histological evidence of amyloid neuropathy and myopathy.

Hereditary transthyretin amyloidosis (ATTR) is a genetically and clinically heterogeneous disease manifesting with predominant peripheral and autonomic neuropathy; cardiomyopathy, or both. ATTR V122I is the most common variant associated with non-neuropathic familial amyloid cardiomyopathy. We present an unusual case of V122I amyloidosis with features of amyloid neuropathy and myopathy, supported by histological confirmation in both sites and diffuse tracer uptake on (99m)Tc-3,3-Diphosphono-1,2-Propanodicarboxylic acid (DPD) scintigraphy throughout skeletal and cardiac muscle. A 64 year old Jamaican man presented with cardiac failure. Cardiac MR revealed infiltrative cardiomyopathy; abdominal fat aspirate confirmed the presence of amyloid, and he was homozygous for the V122I variant of transthyretin. He also described general weakness and EMG demonstrated myopathic features. Sural nerve and vastus lateralis biopsy showed TTR amyloid. The patient is being treated with diflunisal, an oral TTR stabilising agent. Symptomatic myopathy and neuropathy with confirmation of tissue amyloid deposition has not previously been described. Extracardiac amyloidosis has implications for diagnosis and treatment.

Oculoleptomeningeal Amyloidosis associated with transthyretin Leu12Pro in an African patient.

Oculoleptomeningeal amyloidosis is a rare manifestation of hereditary transthyretin (TTR) amyloidosis. Here, we present the first case of leptomeningeal amyloidosis associated with the TTR variant Leu12Pro mutation in an African patient. A 43-year-old right-handed Nigerian man was referred to our centre with rapidly progressive neurological decline. He presented initially with weight loss, confusion, fatigue, and urinary and erectile dysfunction. He then suffered recurrent episodes of slurred speech with right-sided weakness. He went on to develop hearing difficulties and painless paraesthesia. Neurological examination revealed horizontal gaze-evoked nystagmus, brisk jaw jerk, increased tone, brisk reflexes throughout and bilateral heel-shin ataxia. Magnetic resonance imaging showed extensive leptomeningeal enhancement. Cerebrospinal fluid analysis showed a raised protein of 6.4 g/dl. Nerve conduction studies showed an axonal neuropathy. Echocardiography was characteristic of cardiac amyloid. TTR gene sequencing showed that he was heterozygous for the leucine 12 proline mutation. Meningeal and brain biopsy confirmed widespread amyloid angiopathy. TTR amyloidosis is a rare cause of leptomeningeal enhancement, but should be considered if there is evidence of peripheral or autonomic neuropathy with cardiac or ocular involvement. The relationship between different TTR mutations and clinical phenotype, disease course, and response to treatment remains unclear.

A matched comparison of cyclophosphamide, bortezomib and dexamethasone (CVD) versus risk-adapted cyclophosphamide, thalidomide and dexamethasone (CTD) in AL amyloidosis.

Despite improvements in therapy amyloid light-chain (AL) amyloidosis, there are few studies comparing different regimens. Here we present a matched comparison with 69 patients in each cohort examining upfront therapy with cyclophosphamide, bortezomib and dexamethasone (CVD) vs cyclophosphamide, thalidomide and dexamethasone (CTD). On an intention-to-treat basis, the overall response rates were 71.0% vs 79.7% in the CVD and CTD arms, respectively, (P=0.32). A higher complete response (CR) rate was observed in the CVD arm (40.5%) vs CTD (24.6%), P=0.046. One-year overall survival (OS) was 65.2% and 66.7% for CVD and CTD, respectively (P=0.87). The median progression-free survival (PFS) was 28.0 and 14.0 m for CVD and CTD, respectively (P=0.039). In a landmark analysis assessing outcomes performed at 6 months, the CR rate with CVD was 59.6% vs 34.0% for CTD (P=0.03). The 1-year OS was 96% with CVD and 92% with CTD (P=0.40). The median PFS with CVD was not reached and was 19.2 m with CTD, P=0.028). In summary, both regimens are unable to overcome the high rate of early deaths in AL amyloidosis. However, CVD correlates with improved depth of response and superior PFS supporting its use in the frontline setting. Further optimisation and better supportive-care strategies are required to increase the proportion of patients fully benefiting from therapy.

Renal transplantation in systemic amyloidosis-importance of amyloid fibril type and precursor protein abundance.

Renal transplantation remains contentious in patients with systemic amyloidosis due to the risk of graft loss from recurrent amyloid and progressive disease. Outcomes were sought among all patients attending the UK National Amyloidosis Centre who received a renal transplant (RTx) between January 1978 and May 2011. A total of 111 RTx were performed in 104 patients. Eighty-nine percent of patients with end-stage renal disease (ESRD) due to hereditary lysozyme and apolipoprotein A-I amyloidosis received a RTx. Outcomes following RTx were generally excellent in these diseases, reflecting their slow natural history; median graft survival was 13.1 years. Only 20% of patients with ESRD due to AA, AL and fibrinogen amyloidosis received a RTx. Median graft survival was 10.3, 5.8 and 7.3 years in these diseases respectively, and outcomes were influenced by fibril precursor protein supply. Patient survival in AL amyloidosis was 8.9 years among those who had achieved at least a partial clonal response compared to 5.2 years among those who had no response (p = 0.02). Post-RTx chemotherapy was administered successfully to four AL patients. RTx outcome is influenced by amyloid type. Suppression of the fibril precursor protein is desirable in the amyloidoses that have a rapid natural history.

Solid organ transplantation in AL amyloidosis.

Vital organ failure remains common in AL amyloidosis. Solid organ transplantation is contentious because of the multisystem nature of this disease and risk of recurrence in the graft. We report outcome among all AL patients evaluated at the UK National Amyloidosis Centre who received solid organ transplants between 1984 and 2009. Renal, cardiac and liver transplants were performed in 22, 14 and 9 patients respectively, representing <2% of all AL patients assessed during the period. One and 5-year patient survival was 95% and 67% among kidney recipients, 86% and 45% among heart recipients and 33% and 22% among liver recipients. No renal graft failed due to recurrent amyloid during median (range) follow up of 4.8 (0.2-13.3) years. Median patient survival was 9.7 years among 8/14 cardiac transplant recipients who underwent subsequent stem cell transplantation (SCT) and 3.4 years in six patients who did not undergo SCT (p = 0.01). Amyloid was widespread in all liver transplant recipients. Solid organ transplantation has rarely been performed in AL amyloidosis, but these findings demonstrate feasibility and support a role in selected patients.

Evidence that 13-14 di-hydro, 15-keto prostaglandin D(2)-induced airway eosinophilia in guinea-pigs is independent of interleukin-5.

OBJECTIVE AND DESIGN: Prostaglandin D(2) (PGD(2)) has been shown to cause eosinophil, basophil and Th2 cell chemotaxis in vitro and in vivo through an action on the prostaglandin CRTH2 receptor. In the present study, the dependence of PGD(2)-induced eosinophil accumulation in vivo on interleukin-5 (IL-5) blood eosinophilia was investigated. MATERIALS: Guinea-pigs were exposed to aerosols of 13,14di-hydro 15-keto PGD(2) (DK-PGD(2)) or platelet activating factor (PAF) and the eosinophil content of the bronchoalveolar lavage fluid or blood determined. In some experiments, DK-PGD(2) was administered systemically and eosinophilia measured. RESULTS: Aerosols of DK-PGD(2) caused eosinophil accumulation in the lungs 24h after exposure. DK-PGD(2) (10 microg x ml(-1)) -induced airway eosinophilia was inhibited when animals were treated with the CRTH2 receptor antagonist ramatroban. 1-4h after exposure to DK-PGD(2) a significant decrease in blood eosinophil count was measured. The anti-IL-5 antibody TRFK-5 had no inhibitory effect of DK-PGD(2)-induced airway eosinophilia, but abolished airway eosinophilia induced by exposure of guinea-pigs to aerosols of PAF. Intracardiac injection of DK-PGD(2) induced a dose-related increase in blood eosinophil numbers. CONCLUSIONS: It is concluded that, in the guinea-pig, DK-PGD(2)-induced airway eosinophilia is mediated by an action on prostaglandin CRTH2 receptors and that this response appears to be independent of IL-5.

Characterisation of nicotine receptors on human peripheral blood mononuclear cells (PBMC).

AIM AND OBJECTIVE: The aim of the work was to characterise the nAChRs on human PBMC. METHOD: PBMC were isolated from human blood buffy coats provided by the blood transfusion service and were used for radioligand binding studies with [(3)H]-nicotine. RT-PCR experiments were used to determine nAChR subunit expression while immunoblotting experiments were used to confirm that nAChR subunits identified by RT-PCR were translated into protein. RESULTS: Binding studies suggested the presence of one binding site for (-)- nicotine on human peripheral blood lymphocytes. Competition studies showed that only (-)- nicotine, epibatidine and alpha-bungarotoxin, displaced radiolabelled nicotine from cells. RT-PCR studies demonstrated mRNA for alpha4, alpha5, alpha7, beta1 and beta2 nAChRs subunits in PBMC. Expression of mRNA for the a5 subunit of nAChR was observed in all lymphocyte samples tested. In contrast, the expression pattern of mRNAs for alpha4, alpha7, beta1, and beta2 mRNAs subunits of nAChRs, varied between samples. Western blot analysis showed that protein for alpha4, alpha5, and alpha7 and beta2 nAChR subunits was expressed in most, but not all of the PBMC samples tested but some of the bands obtained were faint. CONCLUSION: The results obtained suggest that human PBMC contain nAChRs containing alpha4beta2, alpha4beta2alpha5, and/or alpha7 subunits.

Laparoscopic renal cryotherapy: biology, techniques and outcomes.

AIM: The development of minimally invasive approaches to renal cell carcinoma (RCC) over the last 10 years has given rise to newer therapies such as renal cryotherapy. Patients with significant comorbidities who are not suitable for open surgery may be candidates for this procedure. Herein, we review the biology, techniques and outcomes of laparoscopic renal cryotherapy as performed at our institution. METHODS: We present our initial experience with laparoscopic cryotherapy for the treatment of small, peripheral renal lesions and provide a review of the literature. A retrospective review was performed on our first 25 patients treated with transperitoneal laparoscopic cryotherapy for small peripheral renal lesions by a single surgeon between 2002 and 2003. RESULTS: We treated 25 patients, average age of 65 years (range 32-83) with transperitoneal laparoscopic renal cryotherapy for small, enhancing, peripheral lesions suspicious for RCC. Mean pretreatment creatinine of 1.06 was unchanged after treatment. Mean tumor size was 2.4 cm (range 1.5-3.6 cm), with a mean EBL of 80 mL. Pathology revealed 72% RCC, 2 oncocytomas, one each arterio-nephrosclerosis, inflammatory tissue, focal-segmental glomerulosclerosis, angiomyolipoma and one normal tissue specimen. Average tumor grade was 2.3 (range 2-4). Mean hospital stay was 2.3 days (range 1-5). Three cases were converted to open. Two complications included transfusion and hydronephrosis, both managed conservatively. Mean follow-up is 16.2 months (range 6-36 months). There have been no recurrences to date despite a rigorous surveillance protocol. CONCLUSIONS: Renal cryotherapy is a viable option for nephron sparing surgery in small, peripheral, renal lesions. The procedure is well tolerated, may be considered in patients who are not good candidates for open surgical approaches, results in minimal morbidity, and has very encouraging treatment results. Close surveillance post-treatment is essential. Longer follow-up data will be necessary to establish the durability of laparoscopic renal cryotherapy.

Kinetics of the CO oxidation reaction on Pt(111) studied by in situ high-resolution x-ray photoelectron spectroscopy.

High-resolution x-ray photoelectron spectroscopy has been used to study the kinetics of the CO oxidation reaction on a Pt(111) surface in situ. The study focuses on the interaction of a preadsorbed p(2x2) layer of atomic oxygen with CO dosed using a supersonic molecular beam. Measurements of O 1s and C 1s spectra at 120 K show that CO adsorbs on the oxygen precovered substrate, but no reaction occurs. A maximum CO coverage of 0.23 ML (monolayer) is observed, with CO exclusively bound on on-top sites. In accordance with the literature, bridge sites are blocked by the presence of atomic oxygen. The reaction of CO with preadsorbed O to CO(2) is studied isothermally in a temperature range between 275 and 305 K. The reaction rate initially increases with CO pressure, but saturates at 9x10(-7) mbar. The data indicate that a certain amount of disordered oxygen within the p(2x2) layer acts as a starting point of the reaction and for a given temperature reacts with a higher rate than O in the well-ordered oxygen p(2x2) phase. For the reaction of CO with this ordered phase, the results confirm the assumption of a reaction mechanism, which is restricted to the edges of compact oxygen islands. The activation energy of the reaction is determined to (0.53+/-0.04) eV, with a prefactor of 4.7x10(6+/-0.7) s(-1).

Direct visualization of the gamma secretase-generated carboxyl-terminal domain of the amyloid precursor protein: association with Fe65 and translocation to the nucleus.

Amyloid-beta, the peptide that deposits as senile plaques in Alzheimer's disease, is derived from the amyloid precursor protein (APP) by a gamma secretase-mediated intramembranous cleavage. In addition to amyloid-beta, this cleavage produces a carboxyl-terminal intracellular fragment which has an unknown function. The carboxyl-terminal domain of APP interacts in the cytoplasm with an adapter protein, Fe65. We demonstrate by laser scanning confocal microscopy that a gamma secretase generated APP carboxyl-terminal domain, tagged with green fluorescent protein (GFP), translocates to the nucleus in a manner dependent upon stabilization by the adapter protein Fe65; APP which has been mutated to block interactions with Fe65 cannot be detected in the nucleus. The APP-CT domain continues to interact with Fe65 in the nucleus, as determined by both colocalization and fluorescence resonance energy transfer (FRET). Visualization of the APP-CT-Fe65 complex in the nucleus may serve as a readout for processes that modify gamma secretase release of APP-CT.

Demonstration by fluorescence resonance energy transfer of two sites of interaction between the low-density lipoprotein receptor-related protein and the amyloid precursor protein: role of the intracellular adapter protein Fe65.

Amyloid-beta, the major constituent of senile plaques in Alzheimer's disease, is derived from the amyloid precursor protein (APP) by proteolysis. Kunitz protease inhibitor (KPI) containing forms of APP (APP751/770) interact with a multifunctional endocytic receptor, the low-density lipoprotein receptor-related protein (LRP), which modulates its proteolytic processing affecting production of amyloid-beta. We used fluorescence resonance energy transfer (FRET) using labeled LRP and APP in H4 cell line to examine the subcellular localization and the molecular domains involved in the APP-LRP interaction. KPI-containing forms of APP (APP770) demonstrated FRET with LRP that was sensitive to the LRP inhibitor receptor-associated protein (RAP), suggesting an interaction between the extracellular domains of APP770 and LRP. APP695 also interacts with LRP to lesser degree (as measured by extracellular domain probes), and this ectodomain interaction is not altered by RAP. By using C-terminally tagged LRP and APP, we demonstrate a second site of interaction between the C termini of both APP695 and APP770 and the C terminus of LRP, and that the interactions at these regions are not sensitive to RAP. We next examined the possibility that the C-termini APP-LRP interaction was mediated by Fe65, an adaptor protein that interacts with the cytoplasmic tails of LRP and APP. FRET studies confirmed a close proximity between the amino Fe65 phosphotyrosine binding (PTB) domain and LRP cytoplasmic domain and between the carboxyl Fe65 PTB domain and the APP cytoplasmic domain. These findings demonstrate that LRP interaction with APP occurs via both extracellular and intracellular protein interaction domains.