Trisomy of human chromosome 21 enhances amyloid-ß deposition independently of an extra copy of APP.

Down syndrome, caused by trisomy of chromosome 21, is the single most common risk factor for early-onset Alzheimer's disease. Worldwide approximately 6 million people have Down syndrome, and all these individuals will develop the hallmark amyloid plaques and neurofibrillary tangles of Alzheimer's disease by the age of 40 and the vast majority will go on to develop dementia. Triplication of APP, a gene on chromosome 21, is sufficient to cause early-onset Alzheimer's disease in the absence of Down syndrome. However, whether triplication of other chromosome 21 genes influences disease pathogenesis in the context of Down syndrome is unclear. Here we show, in a mouse model, that triplication of chromosome 21 genes other than APP increases amyloid-ß aggregation, deposition of amyloid-ß plaques and worsens associated cognitive deficits. This indicates that triplication of chromosome 21 genes other than APP is likely to have an important role to play in Alzheimer's disease pathogenesis in individuals who have Down syndrome. We go on to show that the effect of trisomy of chromosome 21 on amyloid-ß aggregation correlates with an unexpected shift in soluble amyloid-ß 40/42 ratio. This alteration in amyloid-ß isoform ratio occurs independently of a change in the carboxypeptidase activity of the γ-secretase complex, which cleaves the peptide from APP, or the rate of extracellular clearance of amyloid-ß. These new mechanistic insights into the role of triplication of genes on chromosome 21, other than APP, in the development of Alzheimer's disease in individuals who have Down syndrome may have implications for the treatment of this common cause of neurodegeneration.

Methods for Molecular Diagnosis of Human Prion Disease.

Human prion diseases are associated with a range of clinical presentations, and they are classified by both clinicopathological syndrome and etiology, with subclassification according to molecular criteria. Here, we describe updated procedures that are currently used within the MRC Prion Unit at UCL to determine a molecular diagnosis of human prion disease. Sequencing of the PRNP open reading frame to establish the presence of pathogenic mutations is described, together with detailed methods for immunoblot or immunohistochemical determination of the presence of abnormal prion protein in the brain or peripheral tissues.

The evolution of an integrated ultrasound curriculum (iUSC) for medical students: 9-year experience.

Interest in ultrasound education in medical schools has increased dramatically in recent years as reflected in a marked increase in publications on the topic and growing attendance at international meetings on ultrasound education. In 2006, the University of South Carolina School of Medicine introduced an integrated ultrasound curriculum (iUSC) across all years of medical school. That curriculum has evolved significantly over the 9 years. A review of the curriculum is presented, including curricular content, methods of delivery of the content, student assessment, and program assessment. Lessons learned in implementing and expanding an integrated ultrasound curriculum are also presented as are thoughts on future directions of undergraduate ultrasound education. Ultrasound has proven to be a valuable active learning tool that can serve as a platform for integrating the medical student curriculum across many disciplines and clinical settings. It is also well-suited for a competency-based model of medical education. Students learn ultrasound well and have embraced it as an important component of their education and future practice of medicine. An international consensus conference on ultrasound education is recommended to help define the essential elements of ultrasound education globally to ensure ultrasound is taught and ultimately practiced to its full potential. Ultrasound has the potential to fundamentally change how we teach and practice medicine to the benefit of learners and patients across the globe.

Transmission Properties of Human PrP 102L Prions Challenge the Relevance of Mouse Models of GSS.

Inherited prion disease (IPD) is caused by autosomal-dominant pathogenic mutations in the human prion protein (PrP) gene (PRNP). A proline to leucine substitution at PrP residue 102 (P102L) is classically associated with Gerstmann-Sträussler-Scheinker (GSS) disease but shows marked clinical and neuropathological variability within kindreds that may be caused by variable propagation of distinct prion strains generated from either PrP 102L or wild type PrP. To-date the transmission properties of prions propagated in P102L patients remain ill-defined. Multiple mouse models of GSS have focused on mutating the corresponding residue of murine PrP (P101L), however murine PrP 101L, a novel PrP primary structure, may not have the repertoire of pathogenic prion conformations necessary to accurately model the human disease. Here we describe the transmission properties of prions generated in human PrP 102L expressing transgenic mice that were generated after primary challenge with ex vivo human GSS P102L or classical CJD prions. We show that distinct strains of prions were generated in these mice dependent upon source of the inoculum (either GSS P102L or CJD brain) and have designated these GSS-102L and CJD-102L prions, respectively. GSS-102L prions have transmission properties distinct from all prion strains seen in sporadic and acquired human prion disease. Significantly, GSS-102L prions appear incapable of transmitting disease to conventional mice expressing wild type mouse PrP, which contrasts strikingly with the reported transmission properties of prions generated in GSS P102L-challenged mice expressing mouse PrP 101L. We conclude that future transgenic modeling of IPDs should focus exclusively on expression of mutant human PrP, as other approaches may generate novel experimental prion strains that are unrelated to human disease.

Factors that influence physicians' and medical students' confidence in counseling patients about physical activity.

Less than half of US adults and two-thirds of US high school students do not meet current US guidelines for physical activity. We examined which factors promoted physicians' and medical students' confidence in counseling patients about physical activity. We established an online exercise survey targeting attending physicians, resident and fellow physicians, and medical students to determine their current level of physical activity and confidence in counseling patients about physical activity. We compared their personal level of physical activity with the 2008 Physical Activity Guidelines of the US Department of Health and Human Services (USDHHS). We administered a survey in 2009 and 2010 that used the short form of the International Physical Activity Questionnaire. A total of 1,949 individuals responded to the survey, of whom 1,751 (i.e., 566 attending physicians, 138 fellow physicians, 806 resident physicians, and 215 medical students) were included in this analysis. After adjusting for their BMI, the odds that physicians and medical students who met USDHHS guidelines for vigorous activity would express confidence in their ability to provide exercise counseling were more than twice that of physicians who did not meet these guidelines. Individuals who were overweight were less likely to be confident than those with normal BMI, after adjusting for whether they met the vigorous exercise guidelines. Physicians with obesity were even less likely to express confidence in regards to exercise counseling. We conclude that physicians and medical students who had a normal BMI and met vigorous USDHHS guidelines were more likely to feel confident about counseling their patients about physical activity. Our findings suggest that graduate medical school education should focus on health promotion in their students, as this will likely lead to improved health behaviors in their students' patient populations.

Inherited prion disease A117V is not simply a proteinopathy but produces prions transmissible to transgenic mice expressing homologous prion protein.

Prions are infectious agents causing fatal neurodegenerative diseases of humans and animals. In humans, these have sporadic, acquired and inherited aetiologies. The inherited prion diseases are caused by one of over 30 coding mutations in the human prion protein (PrP) gene (PRNP) and many of these generate infectious prions as evidenced by their experimental transmissibility by inoculation to laboratory animals. However, some, and in particular an extensively studied type of Gerstmann-Sträussler-Scheinker syndrome (GSS) caused by a PRNP A117V mutation, are thought not to generate infectious prions and instead constitute prion proteinopathies with a quite distinct pathogenetic mechanism. Multiple attempts to transmit A117V GSS have been unsuccessful and typical protease-resistant PrP (PrP(Sc)), pathognomonic of prion disease, is not detected in brain. Pathogenesis is instead attributed to production of an aberrant topological form of PrP, C-terminal transmembrane PrP ((Ctm)PrP). Barriers to transmission of prion strains from one species to another appear to relate to structural compatibility of PrP in host and inoculum and we have therefore produced transgenic mice expressing human 117V PrP. We found that brain tissue from GSS A117V patients did transmit disease to these mice and both the neuropathological features of prion disease and presence of PrP(Sc) was demonstrated in the brains of recipient transgenic mice. This PrP(Sc) rapidly degraded during laboratory analysis, suggesting that the difficulty in its detection in patients with GSS A117V could relate to post-mortem proteolysis. We conclude that GSS A117V is indeed a prion disease although the relative contributions of (Ctm)PrP and prion propagation in neurodegeneration and their pathogenetic interaction remains to be established.

Progressive neuronal inclusion formation and axonal degeneration in CHMP2B mutant transgenic mice.

Mutations in the charged multivesicular body protein 2B (CHMP2B) gene cause frontotemporal lobar degeneration. The mutations lead to C-terminal truncation of the CHMP2B protein. We generated Chmp2b knockout mice and transgenic mice expressing either wild-type or C-terminally truncated mutant CHMP2B. The transgenic CHMP2B mutant mice have decreased survival and show progressive neurodegenerative changes including gliosis and increasing accumulation of p62- and ubiquitin-positive inclusions. The inclusions are negative for the TAR DNA binding protein 43 and fused in sarcoma proteins, mimicking the inclusions observed in patients with CHMP2B mutation. Mice transgenic for mutant CHMP2B also develop an early and progressive axonopathy characterized by numerous amyloid precursor protein-positive axonal swellings, implicating altered axonal function in disease pathogenesis. These findings were not observed in Chmp2b knockout mice or in transgenic mice expressing wild-type CHMP2B, indicating that CHMP2B mutations induce degenerative changes through a gain of function mechanism. These data describe the first mouse model of dementia caused by CHMP2B mutation and provide new insights into the mechanisms of CHMP2B-induced neurodegeneration.

Determining levels of physical activity in attending physicians, resident and fellow physicians and medical students in the USA.

OBJECTIVE: Evidence suggests that the level of physical activity of physicians can be correlated directly with physician counselling patterns about this behaviour. Our objective was to determine if medical students, resident and fellow physicians and attending physicians meet the physical activity guidelines set forth by the US Department of Health and Human Services. METHODS: A representative cross-sectional web-based survey was conducted in June 2009-January 2010 throughout the USA (N=1949). Using the short form of the International Physical Activity Questionnaire, the authors gathered demographical data and information related to physical activity, the level of training, the number of work hours per week, body mass index (BMI), confidence about counselling about physical activity and frequency with which the physical activity is encouraged to his/her patients. RESULTS: Based on the 1949 respondents, attending physicians (84.8%) and medical students (84%) were more likely than resident (73.2%) and fellow physicians (67.9%) to meet physical activity guidelines. CONCLUSION: Physicians and medical students engage in more physical activity and tend to have a lower BMI than the general population. Resident and fellow physicians engage in less physical activity than attending physicians and medical students.

An integrated ultrasound curriculum (iUSC) for medical students: 4-year experience.

A review of the development and implementation of a 4-year medical student integrated ultrasound curriculum is presented. Multiple teaching and assessment modalities are discussed as well as results from testing and student surveys. Lessons learned while establishing the curriculum are summarized. It is concluded that ultrasound is a well received, valuable teaching tool across all 4 years of medical school, and students learn ultrasound well, and they feel their ultrasound experience enhances their medical education.

Effect of fixation on brain and lymphoreticular vCJD prions and bioassay of key positive specimens from a retrospective vCJD prevalence study.

Anonymous screening of lymphoreticular tissues removed during routine surgery has been applied to estimate the UK population prevalence of asymptomatic vCJD prion infection. The retrospective study of Hilton et al (J Pathol 2004; 203: 733-739) found accumulation of abnormal prion protein in three formalin-fixed appendix specimens. This led to an estimated UK prevalence of vCJD infection of ∼1 in 4000, which remains the key evidence supporting current risk reduction measures to reduce iatrogenic transmission of vCJD prions in the UK. Confirmatory testing of these positives has been hampered by the inability to perform immunoblotting of formalin-fixed tissue. Animal transmission studies offer the potential for 'gold standard' confirmatory testing but are limited by both transmission barrier effects and known effects of fixation on scrapie prion titre in experimental models. Here we report the effects of fixation on brain and lymphoreticular human vCJD prions and comparative bioassay of two of the three prevalence study formalin-fixed, paraffin-embedded (FFPE) appendix specimens using transgenic mice expressing human prion protein (PrP). While transgenic mice expressing human PrP 129M readily reported vCJD prion infection after inoculation with frozen vCJD brain or appendix, and also FFPE vCJD brain, no infectivity was detected in FFPE vCJD spleen. No prion transmission was observed from either of the FFPE appendix specimens. The absence of detectable infectivity in fixed, known positive vCJD lymphoreticular tissue precludes interpreting negative transmissions from vCJD prevalence study appendix specimens. In this context, the Hilton et al study should continue to inform risk assessment pending the outcome of larger-scale studies on discarded surgical tissues and autopsy samples.

Magnetization transfer ratio may be a surrogate of spongiform change in human prion diseases.

Human prion diseases are fatal neurodegenerative disorders caused by misfolding of the prion protein. There are no useful biomarkers of disease progression. Cerebral cortex spongiform change, one of the classical pathological features of prion disease, resolves in prion-infected transgenic mice following prion protein gene knockout. We investigated the cross-sectional, longitudinal and post-mortem cerebral magnetization transfer ratios as a surrogate for prion disease pathology. Twenty-three prion disease patients with various prion protein gene mutations and 16 controls underwent magnetization transfer ratio and conventional magnetic resonance imaging at 1.5 T. For each subject, whole-brain, white and grey matter magnetization transfer ratio histogram mean, peak height, peak location, and magnetization transfer ratio at 25th, 50th and 75th percentile were computed and correlated with several cognitive, functional and neuropsychological scales. Highly significant associations were found between whole brain magnetization transfer ratio and prion disease (P < 0.01). Additionally, highly significant correlations were found between magnetization transfer ratio histogram parameters and clinical, functional and neuropsychological scores (P < 0.01). Longitudinally, decline in the Clinician's Dementia Rating scale was correlated with decline in magnetization transfer ratio. To investigate the histological correlates of magnetization transfer ratio, formalin-fixed cerebral and cerebellar hemispheres from 19 patients and six controls underwent magnetization transfer ratio imaging at 1.5 T, with mean magnetization transfer ratio calculated from six regions of interest, and findings were followed-up in six variant Creutzfeldt-Jakob disease cases with 9.4 T high-resolution magnetization transfer imaging on frontal cortex blocks, with semi-quantitative histopathological scoring of spongiosis, astrocytosis and prion protein deposition. Post-mortem magnetization transfer ratios was significantly lower in patients than controls in multiple cortical and subcortical regions, but not frontal white matter. Measurements (9.4 T) revealed a significant and specific negative correlation between cortical magnetization transfer ratios and spongiosis (P = 0.02), but not prion protein deposition or gliosis. The magnetic resonance imaging measurement of magnetization transfer ratios may be an in vivo surrogate for spongiform change and has potential utility as a therapeutic biomarker in human prion disease.

Chronic wasting disease prions are not transmissible to transgenic mice overexpressing human prion protein.

Chronic wasting disease (CWD) is a prion disease that affects free-ranging and captive cervids, including mule deer, white-tailed deer, Rocky Mountain elk and moose. CWD-infected cervids have been reported in 14 USA states, two Canadian provinces and in South Korea. The possibility of a zoonotic transmission of CWD prions via diet is of particular concern in North America where hunting of cervids is a popular sport. To investigate the potential public health risks posed by CWD prions, we have investigated whether intracerebral inoculation of brain and spinal cord from CWD-infected mule deer transmits prion infection to transgenic mice overexpressing human prion protein with methionine or valine at polymorphic residue 129. These transgenic mice have been utilized in extensive transmission studies of human and animal prion disease and are susceptible to BSE and vCJD prions, allowing comparison with CWD. Here, we show that these mice proved entirely resistant to infection with mule deer CWD prions arguing that the transmission barrier associated with this prion strain/host combination is greater than that observed with classical BSE prions. However, it is possible that CWD may be caused by multiple prion strains. Further studies will be required to evaluate the transmission properties of distinct cervid prion strains as they are characterized.

Disruption of endocytic trafficking in frontotemporal dementia with CHMP2B mutations.

Mutations in CHMP2B cause frontotemporal dementia (FTD) in a large Danish pedigree, which is termed FTD linked to chromosome 3 (FTD-3), and also in an unrelated familial FTD patient. CHMP2B is a component of the ESCRT-III complex, which is required for function of the multivesicular body (MVB), an endosomal structure that fuses with the lysosome to degrade endocytosed proteins. We report a novel endosomal pathology in CHMP2B mutation-positive patient brains and also identify and characterize abnormal endosomes in patient fibroblasts. Functional studies demonstrate a specific disruption of endosome-lysosome fusion but not protein sorting by the MVB. We provide evidence for a mechanism for impaired endosome-lysosome fusion whereby mutant CHMP2B constitutively binds to MVBs and prevents recruitment of proteins necessary for fusion to occur, such as Rab7. The fusion of endosomes with lysosomes is required for neuronal function and the data presented therefore suggest a pathogenic mechanism for FTD caused by CHMP2B mutations.

Impact of the foundations of clinical medicine course on USMLE scores.

BACKGROUND: The synthesis of basic and clinical science knowledge during the clerkship years has failed to meet educational expectations. OBJECTIVES: We hypothesized that a small-group course emphasizing the basic science underpinnings of disease, Foundations of Clinical Medicine (FCM), could be integrated into third year clerkships and would not negatively impact the United States Medical Licensure Examination (USMLE) step 2 scores. DESIGN: In 2001-2002, all third year students met weekly in groups of 8-12 clustered within clerkships to discuss the clinical and basic science aspects of prescribed, discipline-specific cases. PARTICIPANTS: Students completing USMLE step 2 between 1999 and 2004 (n = 743). MEASUREMENTS: Course evaluations were compared with the overall institutional average. Bivariate analyses compared the mean USMLE steps 1 and 2 scores across pre- and post-FCM student cohorts. We used multiple linear regression to assess the association between USMLE step 2 scores and FCM cohort controlling for potential confounders. RESULTS: Students' average course evaluation score rose from 66 to 77 (2001-2004) compared to an institutional average of 73. The unadjusted mean USMLE step 1 score was higher for the post-FCM cohort (212.9 vs 207.5, respectively, p < .001) and associated with step 2 scores (estimated coefficient = 0.70, p < .001). Post-FCM cohort (2002-2004; n = 361) mean step 2 scores topped pre-FCM (1999-2001; n = 382) scores (215.9 vs 207.7, respectively, p < .001). FCM cohort remained a significant predictor of higher step 2 scores after adjustment for USMLE step 1 and demographic characteristics (estimated coefficient = 4.3, p = .002). CONCLUSIONS: A curriculum integrating clinical and basic sciences during third year clerkships is feasible and associated with improvement in standardized testing.

Molecular diagnosis of human prion disease.

Human prion diseases are associated with a range of clinical presentations, and they are classified by both clinicopathological syndrome and etiology, with subclassification according to molecular criteria. Here, we describe procedures that are used within the MRC Prion Unit to determine a molecular diagnosis of human prion disease. Sequencing of the PRNP open reading frame to establish the presence of pathogenic mutations is described, together with detailed methods for immunoblot or immunohistochemical determination of the presence of abnormal prion protein in brain or peripheral tissues.

The relationship between health literacy and diabetes knowledge and readiness to take health actions.

PURPOSE: The purpose of this study was to explore the relationship among health literacy, patients' readiness to take health actions, and diabetes knowledge among individuals with type 2 diabetes. METHODS: Sixty-eight patients with type 2 diabetes receiving care in an academic general internal medicine clinic were administered the Rapid Estimate of Adult Literacy in Medicine (REALM) literacy instrument prior to completing the Diabetes Health Belief Model (DHBM) scale and Diabetes Knowledge Test (DKT). Multivariable linear regression was used to assess the association between REALM literacy level, DKT score, DHBM scale score, and most recent hemoglobin A1C level while controlling for other covariates of interest. RESULTS: After controlling for other covariates of interest, no significant association between DHBM scale score and REALM literacy level was found (P = .29). However, both DKT score and most recent hemoglobin A1Clevel were found to be significantly associated with patient literacy (P = .004 and P = .02, respectively). Based on the multivariable model, patients with less than a fourth-grade literacy level had 13% lower DKT scores (95% confidence interval [CI], -28% to -2%; P = .08) and 1.36% higher most recent hemoglobin A1Clevels (95% CI, 1.06% to 1.73%; P = .02) relative to those with a high school literacy level. CONCLUSIONS: Low health literacy is a problem faced by many patients that affects their ability to navigate the health care system and manage their chronic illnesses. While low health literacy was significantly associated with worse glycemic control and poorer disease knowledge in patients with type 2 diabetes, there was no significant relationship with their readiness to take action in disease management.

Brief report: Trainee provider perceptions of group visits.

OBJECTIVE: To evaluate the effect of observing group visits on trainees' perceptions of group visits as a method of health care delivery. RESEARCH DESIGN AND METHODS: Thirty-two trainees assigned to month-long rotations at an academic Internal Medicine Primary Care Clinic serving underinsured patients were recruited to observe between 1 and 4 group visits. Prior to observation of their first, and subsequent to observation of their last group visit, each trainee completed the Patient-Physician Orientation Scale (PPOS), a validated survey evaluating their tendencies toward being patient-centered or provider-centered. Additionally, they completed a Group Visit Questionnaire (GVQ) evaluating their perceptions of group visits as a method of health care delivery. RESULTS: Trainee gender, type, and level of training were similarly represented across the study population of trainees. While there were no significant differences noted on pre- and postobservation PPOS scores, the postobservation GVQs scores were significantly improved after observing at least one group visit (P<.0001). CONCLUSION: Trainees' perceptions of group visits as a method of health care delivery improved significantly after observation of at least 1 group as measured by the GVQ.

Phenotypic heterogeneity in inherited prion disease (P102L) is associated with differential propagation of protease-resistant wild-type and mutant prion protein.

Inherited prion diseases are caused by PRNP coding mutations and display marked phenotypic heterogeneity within families segregating the same pathogenic mutation. A proline-to-leucine substitution at prion protein (PrP) residue 102 (P102L), classically associated with the Gerstmann-Sträussler-Scheinker (GSS) phenotype, also shows marked clinical and pathological heterogeneity, including patients with a Creutzfeldt-Jakob disease (CJD) phenotype. To date, this heterogeneity has been attributed to temporal and spatial variance in the propagation of distinct protease-resistant (PrP(Sc)) isoforms of mutant PrP. Here, using a monoclonal antibody that recognizes wild-type PrP, but not PrP 102L, we reveal a spectrum of involvement of wild-type PrP(Sc) in P102L individuals. PrP(Sc) isoforms derived from wild-type and mutant PrP are distinct both from each other and from those seen in sporadic and acquired CJD. Such differential propagation of disease-related isoforms of wild-type PrP and PrP 102L provides a molecular mechanism for generation of the multiple clinicopathological phenotypes seen in inherited prion disease.

Brief report: Resident recognition of low literacy as a risk factor in hospital readmission.

BACKGROUND: Low literacy is associated with poor self-management of disease and increased hospitalization, yet few studies have explored the extent to which physicians consider literacy in their patient care. OBJECTIVE: To examine trainee recognition of low literacy as a potential factor in patient adherence and hospital readmission. DESIGN AND PARTICIPANTS: Randomized study of 98 Internal Medicine residents and medical students. Trainees reviewed a case history and completed a questionnaire pertaining to a fictional patient's hospital readmission. Case version A contained clues to suggest limited patient literacy skills, while version B did not. Responses were reviewed for mention of low literacy and educational strategies recommended for low-literate patients. RESULTS: Few trainees raised the possibility of low patient literacy, even when provided clues (25% in Group A vs 4% in Group B, P=.003). Furthermore, while most trainees listed patient education as an important means of preventing another readmission, only 16% suggested using a strategy recommended for low-literate adults. CONCLUSION: Few trainees recognized low literacy as a potential factor in patient nonadherence and hospital readmission, and few recommended low-literate educational strategies. Medical residents and students may benefit from additional training in the recognition and counseling of low-literate patients.

Five steps for sustaining effective patient partnership working.

NHS organisations are to recruit and involve patients in planning and delivering health care services. This paper gives practical examples of recruiting and involving patients in this process and a 'five-step cycle' for sustaining effective partnership working between patients and NHS organisations.