Rab12 is a regulator of LRRK2 and its activation by damaged lysosomes

Leucine-rich repeat kinase 2 (LRRK2) variants associated with Parkinson's disease (PD) and Crohn's disease lead to increased phosphorylation of its Rab substrates. While it has been recently shown that perturbations in cellular homeostasis including lysosomal damage can increase LRRK2 activity and localization to lysosomes, the molecular mechanisms by which LRRK2 activity is regulated have remained poorly defined. We performed a targeted siRNA screen to identify regulators of LRRK2 activity and identified Rab12 as a novel modulator of LRRK2-dependent phosphorylation of one of its substrates, Rab10. Using a combination of imaging and immunopurification methods to isolate lysosomes, we demonstrated that Rab12 is actively recruited to damaged lysosomes and leads to a local and LRRK2-dependent increase in Rab10 phosphorylation. PD-linked variants, including LRRK2 R1441G and VPS35 D620N, lead to increased recruitment of LRRK2 to the lysosome and a local elevation in lysosomal levels of pT73 Rab10. Together, these data suggest a conserved mechanism by which Rab12, in response to damage or expression of PD-associated variants, facilitates the recruitment of LRRK2 and phosphorylation of its Rab substrate(s) at the lysosome.

CD98hc is a target for brain delivery of biotherapeutics

Brain exposure of systemically administered biotherapeutics is highly restricted by the blood-brain barrier (BBB). Here, we report the engineering and characterization of a BBB transport vehicle targeting the CD98 heavy chain (CD98hc or SLC3A2) of heterodimeric amino acid transporters (TVCD98hc). The pharmacokinetic and biodistribution properties of a CD98hc antibody transport vehicle (ATVCD98hc) are assessed in humanized CD98hc knock-in mice and cynomolgus monkeys. Compared to most existing BBB platforms targeting the transferrin receptor, peripherally administered ATVCD98hc demonstrates differentiated brain delivery with markedly slower and more prolonged kinetic properties. Specific biodistribution profiles within the brain parenchyma can be modulated by introducing Fc mutations on ATVCD98hc that impact FcγR engagement, changing the valency of CD98hc binding, and by altering the extent of target engagement with Fabs. Our study establishes TVCD98hc as a modular brain delivery platform with favorable kinetic, biodistribution, and safety properties distinct from previously reported BBB platforms.

A TREM2-activating antibody with a blood-brain barrier transport vehicle enhances microglial metabolism in Alzheimer's disease models

Loss-of-function variants of TREM2 are associated with increased risk of Alzheimer's disease (AD), suggesting that activation of this innate immune receptor may be a useful therapeutic strategy. Here we describe a high-affinity human TREM2-activating antibody engineered with a monovalent transferrin receptor (TfR) binding site, termed antibody transport vehicle (ATV), to facilitate blood-brain barrier transcytosis. Upon peripheral delivery in mice, ATV:TREM2 showed improved brain biodistribution and enhanced signaling compared to a standard anti-TREM2 antibody. In human induced pluripotent stem cell (iPSC)-derived microglia, ATV:TREM2 induced proliferation and improved mitochondrial metabolism. Single-cell RNA sequencing and morphometry revealed that ATV:TREM2 shifted microglia to metabolically responsive states, which were distinct from those induced by amyloid pathology. In an AD mouse model, ATV:TREM2 boosted brain microglial activity and glucose metabolism. Thus, ATV:TREM2 represents a promising approach to improve microglial function and treat brain hypometabolism found in patients with AD.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Compromised Neurocircuitry in Chronic Blast-Related Mild Traumatic Brain Injury

The aim of this study was to apply recently developed automated fiber segmentation and quantification methods using diffusion tensor imaging (DTI) and DTI-based deterministic and probabilistic tractography to access local and global diffusion changes in blast-induced mild traumatic brain injury (bmTBI). Two hundred and two (202) male active US service members who reported persistent post-concussion symptoms for more than 6 months after injury were recruited. An additional forty (40) male military controls were included for comparison. DTI results were examined in relation to post-concussion and post-traumatic stress disorder (PTSD) symptoms. No significant group difference in DTI metrics was found using voxel-wise analysis. However, group comparison using tract profile analysis and tract specific analysis, as well as single subject analysis using tract profile analysis revealed the most prominent white matter microstructural injury in chronic bmTBI patients over the frontal fiber tracts, that is, the front-limbic projection fibers (cingulum bundle, uncinate fasciculus), the fronto-parieto-temporal association fibers (superior longitudinal fasciculus), and the fronto-striatal pathways (anterior thalamic radiation). Effects were noted to be sensitive to the number of previous blast exposures, with a negative association between fractional anisotropy (FA) and time since most severe blast exposure in a subset of the multiple blast-exposed group. However, these patterns were not observed in the subgroups classified using macrostructural changes (T2 white matter hyperintensities). Moreover, post-concussion symptoms and PTSD symptoms, as well as neuropsychological function were associated with low FA in the major nodes of compromised neurocircuitry. Hum Brain Mapp 38:352-369, 2017. © 2016 Wiley Periodicals, Inc.

Polarization Control via He-Ion Beam Induced Nanofabrication in Layered Ferroelectric Semiconductors

Rapid advances in nanoscience rely on continuous improvements of material manipulation at near-atomic scales. Currently, the workhorse of nanofabrication is resist-based lithography and its various derivatives. However, the use of local electron, ion, and physical probe methods is expanding, driven largely by the need for fabrication without the multistep preparation processes that can result in contamination from resists and solvents. Furthermore, probe-based methods extend beyond nanofabrication to nanomanipulation and to imaging which are all vital for a rapid transition to the prototyping and testing of devices. In this work we study helium ion interactions with the surface of bulk copper indium thiophosphate CuM(III)P2X6 (M = Cr, In; X= S, Se), a novel layered 2D material, with a Helium Ion Microscope (HIM). Using this technique, we are able to control ferrielectric domains and grow conical nanostructures with enhanced conductivity whose material volumes scale with the beam dosage. Compared to the copper indium thiophosphate (CITP) from which they grow, the nanostructures are oxygen rich, sulfur poor, and with virtually unchanged copper concentration as confirmed by energy-dispersive X-ray spectroscopy (EDX). Scanning electron microscopy (SEM) imaging contrast as well as scanning microwave microscopy (SMM) measurements suggest enhanced conductivity in the formed particles, whereas atomic force microscopy (AFM) measurements indicate that the produced structures have lower dissipation and are softer as compared to the CITP.

Imaging Cerebral Microhemorrhages in Military Service Members with Chronic Traumatic Brain Injury

PURPOSE

To detect cerebral microhemorrhages in military service members with chronic traumatic brain injury by using susceptibility-weighted magnetic resonance (MR) imaging. The longitudinal evolution of microhemorrhages was monitored in a subset of patients by using quantitative susceptibility mapping.

MATERIALS AND METHODS

The study was approved by the Walter Reed National Military Medical Center institutional review board and is compliant with HIPAA guidelines. All participants underwent two-dimensional conventional gradient-recalled-echo MR imaging and three-dimensional flow-compensated multiecho gradient-recalled-echo MR imaging (processed to generate susceptibility-weighted images and quantitative susceptibility maps), and a subset of patients underwent follow-up imaging. Microhemorrhages were identified by two radiologists independently. Comparisons of microhemorrhage number, size, and magnetic susceptibility derived from quantitative susceptibility maps between baseline and follow-up imaging examinations were performed by using the paired t test.

RESULTS

Among the 603 patients, cerebral microhemorrhages were identified in 43 patients, with six excluded for further analysis owing to artifacts. Seventy-seven percent (451 of 585) of the microhemorrhages on susceptibility-weighted images had a more conspicuous appearance than on gradient-recalled-echo images. Thirteen of the 37 patients underwent follow-up imaging examinations. In these patients, a smaller number of microhemorrhages were identified at follow-up imaging compared with baseline on quantitative susceptibility maps (mean ± standard deviation, 9.8 microhemorrhages ± 12.8 vs 13.7 microhemorrhages ± 16.6; P = .019). Quantitative susceptibility mapping-derived quantitative measures of microhemorrhages also decreased over time: -0.85 mm(3) per day ± 1.59 for total volume (P = .039) and -0.10 parts per billion per day ± 0.14 for mean magnetic susceptibility (P = .016).

CONCLUSION

The number of microhemorrhages and quantitative susceptibility mapping-derived quantitative measures of microhemorrhages all decreased over time, suggesting that hemosiderin products undergo continued, subtle evolution in the chronic stage.

Diffraction imaging in a He+ ion beam scanning transmission microscope

The scanning helium ion microscope has been used in transmission mode to investigate both the feasibility of this approach and the utility of the signal content and the image information available. Operating at 40 keV the penetration of the ion beam, and the imaging resolution achieved, in MgO crystals was found to be in good agreement with values predicted by Monte Carlo modeling. The bright-field and annular dark-field signals displayed the anticipated contrasts associated with beam absorption and scattering. In addition, the diffraction of the He ion beam within the sample gave rise to crystallographic contrast effects in the form of thickness fringes and dislocation images. Scanning transmission He ion microscopy thus achieves useful sample penetration and provides nanometer scale resolution, high contrast images of crystalline materials and crystal defects even at modest beam energies.

Convolution and correlation: a case study of scanning imaging and analysis systems

The relationship between convolution/correlation operation and the data acquisition process of the scanning microscope and spectrometer families is analyzed. It is shown that a coordinate or event sensitive detector, and the intrinsic or extrinsic property of the specimen response, are two important factors in distinguishing the data acquisition mode of such systems. Four types of convolution- and correlation-based modes are extracted to illuminate the physical characteristics of scanning imaging and analysis systems by focusing on the probe, specimen, detector, and their relationships. Criteria for identifying these modes are explored. In addition, the physical meanings of general existing coefficients between the independent variables of convolution and correlation are investigated.

Posttraumatic stress reactions after injury

BACKGROUND

Many individuals experience psychological distress after injury. It is unclear whether poor psychological outcome reflects pretrauma variables.

METHODS

In a prospective, cross-sectional study, 152 accident and emergency department patients with physical injuries and an acute stress reaction completed trauma and psychometric questionnaires, including the Impact of Event Scale and the Hospital Anxiety and Depression Scale.

RESULTS

Although levels of pretrauma social, occupational, and familial functioning were high, and the modal Abbreviated Injury Scale score was 1, there were high levels of psychological distress at 3 weeks. Mean Hospital Anxiety and Depression Scale anxiety and depression scores were 11.8 (SD, 4.4) and 8.7 (SD, 4.4), respectively. The mean total Impact of Event Scale score was 46.0 (SD, 16.1). Stepwise linear regression analysis found unemployment and previous history of trauma to be associated with increased symptoms of traumatic stress.

CONCLUSION

Trauma patients with high levels of pretrauma functioning may develop acute psychological distress. Unemployment and previous trauma increase risk. Psychological wellbeing should be considered in routine injury assessments.

Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers

The medicinal properties of curcumin obtained from Curcuma longa L. cannot be utilised because of poor bioavailability due to its rapid metabolism in the liver and intestinal wall. In this study, the effect of combining piperine, a known inhibitor of hepatic and intestinal glucuronidation, was evaluated on the bioavailability of curcumin in rats and healthy human volunteers. When curcumin was given alone, in the dose 2 g/kg to rats, moderate serum concentrations were achieved over a period of 4 h. Concomitant administration of piperine 20 mg/kg increased the serum concentration of curcumin for a short period of 1-2 h post drug. Time to maximum was significantly increased (P < 0.02) while elimination half life and clearance significantly decreased (P < 0.02), and the bioavailability was increased by 154%. On the other hand in humans after a dose of 2 g curcumin alone, serum levels were either undetectable or very low. Concomitant administration of piperine 20 mg produced much higher concentrations from 0.25 to 1 h post drug (P < 0.01 at 0.25 and 0.5 h; P < 0.001 at 1 h), the increase in bioavailability was 2000%. The study shows that in the dosages used, piperine enhances the serum concentration, extent of absorption and bioavailability of curcumin in both rats and humans with no adverse effects.

Fabrication of Au/p-Si Schottky barrier for EBIC study

A simple method for the fabrication of a Au/p-Si Schottky barrier suitable for electron beam induced current (EBIC) study has been developed. The mechanical and electrical properties of the fabricated Au/p-Si Schottky barriers have been tested, and EBIC measurements of the dislocation contrast have been conducted using the fabricated Schottky barriers.

Emotional, behavioral, and HIV risks associated with sexual abuse among adult homosexual and bisexual men

From May 1989 through April 1990, 1,001 adult homosexual and bisexual men attending urban sexually transmitted disease clinics were interviewed regarding abusive sexual contacts during childhood and adolescence. Sexual abuse was found to be significantly associated with mental health counseling and hospitalization, psychoactive substance use, depression, suicidal thought or actions, social support, sexual identity development, HIV risk behavior including unprotected and intercourse and injecting drug use, and risk of sexually transmitted diseases including HIV infection. Data suggest that sexual abuse may have a wide-ranging influence on the quality of life and health risk behavior of homosexual men. Increased awareness as to the potential outcomes of male sexual abuse is critically important to the design and implementation of medical and psychological services for sexually abused men.

Failure to disclose HIV risk among gay and bisexual men attending sexually transmitted disease clinics

We analyzed data from a multisite study of 1,063 gay or bisexual men attending sexually transmitted disease clinics to evaluate factors predicting failure to disclose human immunodeficiency virus (HIV) risk behaviors to clinic staff and the extent of such failure. We compared data from a brief screening assessment on unprotected anal and oral sex with data on the same behaviors from a subsequent detailed interview. We also compared behavioral data from screening and the interview with data on diagnoses of rectal gonorrhea abstracted from medical charts. Of 523 men reporting unprotected anal sex at interview, 29% failed to report this behavior at screening. Men failing to disclose unprotected anal sex were also less likely to disclose engaging in unprotected oral sex. Among men reporting no unprotected anal sex, either at screening or interview, 1.6% were diagnosed with rectal gonorrhea. Logistic regression analyses comparing men who did and did not disclose at screening having engaged in unprotected anal sex showed that men who failed to disclose reported greater involvement in gay organizations, greater perceived peer support for condoms, fewer episodes of unprotected anal sex in the last four months, and lower rates of substance abuse treatment. Our data suggest that men who failed to disclose may have lower risk levels, and may be more integrated into the gay community. Brief interviews, as opposed to detailed ones, also may underestimate incidence of unsafe sex. Where feasible, HIV risk assessment and counseling and laboratory screening should be routinely provided to all clinic attendees, regardless of self-reports.

Homosexual men who engage in high-risk sexual behavior. A multicenter comparison

To describe homosexual men who continue to engage in unprotected oral and anal sex, 601 men who attended three urban STD clinics and who had engaged in these behaviors with a male partner in the previous 4 months were interviewed regarding their sexual and drug-use behaviors. Although approximately one fourth of participants had engaged in 1 to 2 episodes of unprotected anal sex, more than 20% reported engaging in greater than 23 episodes. Higher frequency of anal sex was associated with lower condom use rates. Although 50% had primary relationships, less than 22% had sex with just one partner, and less than 10% were in relationships concordant for HIV-antibody status. Multiple regression analyses showed that number of drugs used each month, sex in a steady relationship, and Hispanic ethnicity were the most consistent predictors of risk behavior across sites. Careful evaluation of the diverse nature and characteristics of these men is essential to target risk-reduction programs for this population.

Influence of the cholinergic agonist RS 86 on normal sleep: sex and age effects

In 36 healthy control subjects (21 females, 15 males; age range 18-65 years; mean age 41.8 years, SD 15.6 years), a bedtime dose of 1.5 mg RS 86, an orally acting cholinergic agonist, shortened rapid eye movement (REM) latency, increased REM sleep, and decreased slow-wave sleep. Six of the subjects (greater than 40 years old) even displayed sleep-onset REM periods after the drug. Results of the present study agree well with those of studies using other cholinomimetics (i.e., physostigmine, arecholine) and confirm the importance of the cholinergic system for REM sleep regulation. Since RS 86 mimicked some of the REM sleep abnormalities specific for patients with depressive disorders, the cholinergic system may play a role in the pathogenesis and pathophysiology of depressive diseases.