α-Synuclein occurs physiologically as a helically folded tetramer that resists aggregation.

Parkinson's disease is the second most common neurodegenerative disorder. Growing evidence indicates a causative role of misfolded forms of the protein α-synuclein in the pathogenesis of Parkinson's disease. Intraneuronal aggregates of α-synuclein occur in Lewy bodies and Lewy neurites, the cytopathological hallmarks of Parkinson's disease and related disorders called synucleinopathies. α-Synuclein has long been defined as a 'natively unfolded' monomer of about 14 kDa (ref. 6) that is believed to acquire α-helical secondary structure only upon binding to lipid vesicles. This concept derives from the widespread use of recombinant bacterial expression protocols for in vitro studies, and of overexpression, sample heating and/or denaturing gels for cell culture and tissue studies. In contrast, we report that endogenous α-synuclein isolated and analysed under non-denaturing conditions from neuronal and non-neuronal cell lines, brain tissue and living human cells occurs in large part as a folded tetramer of about 58 kDa. Several methods, including analytical ultracentrifugation, scanning transmission electron microscopy and in vitro cell crosslinking confirmed the occurrence of the tetramer. Native, cell-derived α-synuclein showed α-helical structure without lipid addition and had much greater lipid-binding capacity than the recombinant α-synuclein studied heretofore. Whereas recombinantly expressed monomers readily aggregated into amyloid-like fibrils in vitro, native human tetramers underwent little or no amyloid-like aggregation. On the basis of these findings, we propose that destabilization of the helically folded tetramer precedes α-synuclein misfolding and aggregation in Parkinson's disease and other human synucleinopathies, and that small molecules that stabilize the physiological tetramer could reduce α-synuclein pathogenicity.

Complete sequences of 4 viral hemorrhagic septicemia virus IVb isolates and their virulence in northern pike fry.

Four viral hemorrhagic septicemia virus (VHSV) genotype IVb isolates were sequenced, their genetic variation explored, and comparative virulence assayed with experimental infections of northern pike Esox lucius fry. In addition to the type strain MI03, the complete 11183 bp genome of the first round goby Neogobius melanostomus isolate from the St. Lawrence River, and the 2013 and 2014 isolates from gizzard shad Dorosoma cepedianum die-offs in Irondequoit Bay, Lake Ontario and Dunkirk Harbor, Lake Erie were all deep sequenced on an Illumina platform. Mutations documented in the 11 yr since the MI03 index case from Lake St. Clair muskellunge Esox masquinongy showed 87 polymorphisms among the 4 isolates. Twenty-six mutations were non-synonymous and located at 18 different positions within the matrix protein, glycoprotein, non-virion protein, and RNA polymerase genes. The same 4 isolates were used to infect northern pike fry by a single 1 h bath exposure. Cumulative percent mortality varied from 42.5 to 62.5%. VHSV was detected in 57% (41/72) of the survivors at the end of the 21-d trial, suggesting that the virus was not rapidly cleared. Lesions were observed in many of the moribund and dead northern pike, such as hemorrhaging in the skin and fins, as well as hydrocephalus. Mean viral load measured from the trunk and visceral tissues of MI03-infected pike was significantly higher than the quantities detected in fish infected with the most recent isolates of genotype IVb, but there were no differences in cumulative mortality observed.

Assistant instructors facilitate simulation for medical students.

BACKGROUND: A procedural training protocol for medical students must be cognizant of faculty opportunity costs, which may preclude individually supervised practice. Meanwhile, sporadic exposure in large group settings yields suboptimal proficiency. The purpose of this study is to assess the effectiveness of undergraduate assistant instructors in providing one-on-one simulation-based instruction for basic invasive techniques. MATERIALS AND METHODS: Investigators designed proficiency-based checklists by faculty consensus for three simulation tasks as follows: orotracheal intubation, central venous catheterization, and suturing. Four undergraduate students were trained as instructors. Interrater agreement between instructors using the task checklists ranged from 0.754-0.866. Instructors conducted up to seven flexibly scheduled, one-on-one practice sessions with clinically inexperienced medical student participants. Sessions comprised repetitive task attempts with an evaluation after every attempt. On completion of the training protocol, participants underwent evaluation by an experienced surgeon blinded to practice session performance. Study participants were surveyed to assess satisfaction. RESULTS: Twenty-nine participants completed the study. Median total practice time was 8.75 h (interquartile range 7.12-8.75). Posttest pass rates were 93% (26/28), 71% (20/28), and 68% (19/28) for suturing, intubation, and central venous catheterization, respectively. Ninety-seven percent (27/28) of participants were satisfied with their experience, and 62% (18/29) advocated for protocol adoption into the standard preclinical curriculum. Estimated cost saved using student instructors, based on departmental collections for surgical faculty, was $43,760. CONCLUSIONS: Clinically inexperienced assistants may be trained as instructors for basic simulation tasks with excellent interrater reliability. Deploying these assistant instructors makes effective, one-on-one technical training for preclinical medical students financially feasible.

Verification of accurate technical insight: a prerequisite for self-directed surgical training.

Simulation-based surgical skills training during preclinical education is a persistent challenge due to time constraints of trainees and instructors alike. Self-directed practice is resource-efficient and flexible; however, insight into technical proficiency among trainees is often lacking. The purpose of this study is to prospectively assess the accuracy of self-assessments among medical students learning basic surgical suturing. Over seven weekly practice sessions, preclinical medical students performed serial repetitions of a simulation-based suturing task under one-on-one observation by one of four trainers. Following each task repetition, self- and trainer-assessments (SA-TA) were performed using a 36-point weighted checklist of technical standards developed a priori by expert consensus. Upon study completion, agreement between SA and TA was measured using weighted Cohen's kappa coefficients. Twenty-nine medical students each performed a median of 25 suture task repetitions (IQR 21.5-28). Self-assessments tended to overestimate proficiency during the first tertile of practice attempts. Agreement between SA and TA improved with experience, such that the weighted kappa statistics for the two-handed and instrument ties were >0.81 after 18-21 task attempts. Inexperienced trainees frequently overestimate technical proficiency through self-assessments. However, this bias diminishes with repetitive practice. Only after trainees have attained the capacity to accurately self-assess can effective self-directed learning take place.

Intestinal SR-BI is upregulated in insulin-resistant states and is associated with overproduction of intestinal apoB48-containing lipoproteins.

Intestinal lipid dysregulation is a common feature of insulin-resistant states. The present study investigated alterations in gene expression of key proteins involved in the active absorption of dietary fat and cholesterol in response to development of insulin resistance. Studies were conducted in two diet-induced animal models of insulin resistance: fructose-fed hamster and high-fat-fed mouse. Changes in the mRNA abundance of lipid transporters, adenosine triphosphate cassette (ABC) G5, ABCG8, FA-CoA ligase fatty acid translocase P4, Niemann-Pick C1-Like1 (NPC1L1), fatty acid transport protein 4 (FATP4), and Scavenger Receptor Class B Type I (SR-BI), were assessed in intestinal fragments (duodenum, jejunum, and ileum) using quantitative real-time PCR. Of all the transporters evaluated, SR-B1 showed the most significant changes in both animal models examined. A marked stimulation of SR-B1 expression was observed in all intestinal segments examined in both insulin-resistant animal models. The link between SR-BI expression and intestinal lipoprotein production was then examined in the Caco-2 cell model. SR-B1 overexpression in Caco-2 cells increased apolipoprotein B (apoB) 100 and apoB48 secretion, whereas RNAi knock down of SR-B1 decreased secretion of both apoB100 and apoB48. We also observed changes in subcellular distribution of SR-B1 in response to exogenous lipid and insulin. Confocal microscopy revealed marked changes in SR-BI subcellular distribution in response to both exogenous lipids (oleate) and insulin. In summary, marked stimulation of intestinal SR-BI occurs in vivo in animal models of diet-induced insulin resistance, and modulation of SR-BI in vitro regulates production of apoB-containing lipoprotein particles. We postulate that apical and/or basolateral SR-BI may play an important role in intestinal chylomicron production and may contribute to chylomicron overproduction normally observed in insulin-resistant states.

A single-blinded, randomized pilot study to evaluate the effect of exercise-induced sweat on truncal acne.

To assess the effect of exercise-induced sweat on truncal acne, a prospective, single-blinded, randomized, controlled, institution review board-approved clinical trial was conducted on physically active males. Subjects were instructed to exercise long enough to break a sweat 5 days a week for 2 weeks. Group 1 did not exercise (n = 7), group 2 showered within 1 hour of exercise (n = 8), and group 3 waited at least 4 hours to shower after exercising (n = 8). No statistically significant differences in truncal acne were noted between (p = 0.84) nor within (p = 0.74 for group 1, 0.07 for group 2, and 0.09 for group 3) study groups at the end of the study period.

Reporting of ethical review of clinical research submitted to the Journal of the American Academy of Dermatology.

BACKGROUND: In recent years there has been an increasing focus on human subject protection and on documentation of ethical review in published clinical research. The JAAD clearly states in its instructions to authors, which adhere to the guidelines set forth by the International Committee of Medical Journal Editors, "studies involving live human subjects must have been approved by the author's Institutional Review Board or its equivalent." OBJECTIVE: To determine what proportion of prospective studies on human subjects submitted to the clinical trials and therapeutics section lacked mention of review by an ethics board and to determine the outcome of these manuscripts. METHODS: We reviewed 150 prospective studies submitted from July 1, 2004 to January 16, 2006 to a single associate editor, who receives the majority of reports requiring ethics board review. RESULTS: Of 150 prospective studies, 36% (n = 54) had no mention of ethics review or consent, whereas 15% (n = 22) mentioned consent but not ethics review. Forty-two papers were returned asking for ethics information, and of these, 48% were resubmitted with confirmation of ethics review, 22% were withdrawn, 12% were never resubmitted, 12% responded that ethical review was not obtained, and 7% were clarified as exempt from review. Of the 150 papers, 45% were from US authors and 55% were from international authors. Sixty-seven percent of US papers and 35% of international papers included ethics board information (P

Cumulative sum: An individualized proficiency metric for laparoscopic fundamentals.

BACKGROUND: A reliable metric of technical proficiency is indispensable to the training of fellows and residents. The purpose of this study was to determine whether cumulative sum (Cusum) has predictive validity in laparoscopic training. We hypothesized that Cusum would be a better predictor of technical ability in fundamentals of laparoscopic surgery (FLS) than traditional practice volume metrics. METHODS: Twenty medical students were recruited to practice three FLS tasks: peg transfer, circle cut, and intracorporeal knot tie. Up to 7hours of self-directed practice was allotted to each participant. Practice attempts were scored by standard FLS criteria and monitored via Cusum. Each participant's terminal Cusum performance was analyzed retrospectively. Posttests were conducted by faculty blinded to practice performance. RESULTS: Eighteen participants completed the study (90%). Median adjusted posttest scores were 102.3, 84.1, and 78.6 for peg transfer, circle cut, and knot tie, respectively. For the knot tie task, participants who exceeded the Cusum decision interval during their final practice attempts performed significantly higher on posttesting (81.2 vs 71.5, p=0.015). Knot tie terminal Cusum score was positively associated with posttest performance after adjusting for practice volume (p=0.031). Total practice volume and practice time were not significantly associated with posttest performance for any FLS task. CONCLUSION: Cusum score is a more valid representation of FLS proficiency than practice volume or practice time. Incorporating Cusum in a clinical setting may promote more efficient allocation of time resources and operative volume.

Adaptive simulation training using cumulative sum: a randomized prospective trial.

BACKGROUND: Cumulative sum (Cusum) is a novel tool that can facilitate adaptive, individualized training curricula. The purpose of this study was to use Cusum to streamline simulation-based training. METHODS: Preclinical medical students were randomized to Cusum or control arms and practiced suturing, intubation, and central venous catheterization in simulation. Control participants practiced between 8 and 9 hours each. Cusum participants practiced until Cusum proficient in all tasks. Group comparisons of blinded post-test evaluations were performed using Wilcoxon rank sum. RESULTS: Forty-eight participants completed the study. Average post-test composite score was 92.1% for Cusum and 93.5% for control (P = .71). Cusum participants practiced 19% fewer hours than control group participants (7.12 vs 8.75 hours, P < .001). Cusum detected proficiency relapses during practice among 7 (29%) participants for suturing and 10 (40%) for intubation. CONCLUSIONS: In this comparison between adaptive and volume-based curricula in surgical training, Cusum promoted more efficient time utilization while maintaining excellent results.

Predicting surgical skill acquisition in preclinical medical students.

BACKGROUND: The purpose of this study was to identify factors that predict medical student success in acquiring invasive procedural skills. We hypothesized that students with interest in surgery and with prior procedural experience would have higher rates of success. METHODS: Preclinical students were enrolled in a simulation course comprised of suturing, intubation, and central venous catheterization. Students completed surveys to describe demographics, specialty interest area, prior experience, and confidence. Using linear regression, variables predictive of proficiency were identified. RESULTS: Forty-five participants completed the course. Under univariate analysis, composite pretest score was inversely associated with confidence (P = .039). Under multivariable analysis, female gender was associated with higher pretest suturing score (P = .016). Male gender (P = .029) and high confidence (P = .021) were associated with greater improvement in suturing. CONCLUSIONS: Among novices, higher confidence can predict lower baseline technical proficiency. Although females had higher pretest suturing scores, high confidence and male gender were associated with the greatest degree of improvement.

Metabolic mechanisms of methanol/formaldehyde in isolated rat hepatocytes: carbonyl-metabolizing enzymes versus oxidative stress.

Methanol (CH(3)OH), a common industrial solvent, is metabolized to toxic compounds by several enzymatic as well as free radical pathways. Identifying which process best enhances or prevents CH(3)OH-induced cytotoxicity could provide insight into the molecular basis for acute CH(3)OH-induced hepatoxicity. Metabolic pathways studied include those found in 1) an isolated hepatocyte system and 2) cell-free systems. Accelerated Cytotoxicity Mechanism Screening (ACMS) techniques demonstrated that CH(3)OH had little toxicity towards rat hepatocytes in 95% O(2), even at 2M concentration, whereas 50 mM was the estimated LC(50) (2h) in 1% O(2), estimated to be the physiological concentration in the centrilobular region of the liver and also the target region for ethanol toxicity. Cytotoxicity was attributed to increased NADH levels caused by CH(3)OH metabolism, catalyzed by ADH1, resulting in reductive stress, which reduced and released ferrous iron from Ferritin causing oxygen activation. A similar cytotoxic mechanism at 1% O(2) was previous found for ethanol. With 95% O(2), the addition of Fe(II)/H(2)O(2), at non-toxic concentrations were the most effective agents for increasing hepatocyte toxicity induced by 1M CH(3)OH, with a 3-fold increase in cytotoxicity and ROS formation. Iron chelators, desferoxamine, and NADH oxidizers and ATP generators, e.g. fructose, also protected hepatocytes and decreased ROS formation and cytotoxicity. Hepatocyte protein carbonylation induced by formaldehyde (HCHO) formation was also increased about 4-fold, when CH(3)OH was oxidized by the Fenton-like system, Fe(II)/H(2)O(2), and correlated with increased cytotoxicity. In a cell-free bovine serum albumin system, Fe(II)/H(2)O(2) also increased CH(3)OH oxidation as well as HCHO protein carbonylation. Nontoxic ferrous iron and a H(2)O(2) generating system increased HCHO-induced cytotoxicity and hepatocyte protein carbonylation. In addition, HCHO cytotoxicity was markedly increased by ADH1 and ALDH2 inhibitors or GSH-depleted hepatocytes. Increased HCHO concentration levels correlated with increased HCHO-induced protein carbonylation in hepatocytes. These results suggest that CH(3)OH at 1% O(2) involves activation of the Fenton system to form HCHO. However, at higher O(2) levels, radicals generated through Fe(II)/H(2)O(2) can oxidize CH(3)OH/HCHO to form pro-oxidant radicals and lead to increased oxidative stress through protein carbonylation and ROS formation which ultimately causes cell death.

A single-blinded, randomized, controlled clinical trial evaluating the effect of face washing on acne vulgaris.

Despite the common recommendation to wash the face twice daily with a mild cleanser, there is little published evidence to support the practice. Indeed, while the general public believes that cleaner skin will result in fewer blemishes, dermatologists often warn that overwashing and scrubbing can exacerbate the condition. To clarify the effect of frequency of face washing on acne vulgaris, we designed a single-blinded, randomized, controlled clinical trial to be conducted on males with mild to moderate acne vulgaris. Subjects washed their faces twice daily for 2 weeks with a standard mild cleanser before being randomized to one of three study arms, in which face washing was to be done once, twice, or four times a day for 6 weeks. At the end of the study no statistically significant differences were noted between groups. However, significant improvements in both open comedones and total noninflammatory lesions were observed in the group washing twice a day. Worsening of acne condition was observed in the study group washing once a day, with significant increases in erythema, papules, and total inflammatory lesions. We concluded that slight support exists, both in terms of efficacy and convenience, for the recommendation to wash the face twice daily with a mild cleanser. However, excessive face washing may not be as culpable as previously thought.