Dorsolateral prefrontal cortex excitability abnormalities in Alzheimer's Dementia: Findings from transcranial magnetic stimulation and electroencephalography study

There is some evidence of cortical hyper-excitability in Alzheimer's Dementia (AD) but its relationship with cognition is not clear. In this study, we assessed dorsolateral prefrontal cortex (DLPFC) excitability and its relationship with cognition in AD. Twenty-four participants with AD (mean [SD] age = 74.1 [7.2] years) and eleven elderly healthy controls (HC) (mean [SD] age = 68.8 [7.3] years) were recruited. Transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG) was used to assess cortical excitability. Cortical evoked activity (CEA) between 25 and 80 ms post-TMS stimulus was calculated as the primary measure of cortical excitability. TMS-evoked potential peak (TEP) amplitudes (P30, N45 and P60) were also calculated. Cognition was assessed using Montreal Cognitive Assessment (MoCA), Executive Interview (EXIT) and Cambridge Neuropsychological Test Automated Battery Stockings of Cambridge (SOC). There was no difference in TMS stimulus intensity between the groups. DLPFC-CEA was higher in the AD (mean [SD] = 134.64 [90.22] μV) than the HC group (mean [SD] = 82.65 [40.28] μV; t₃₃ = 2.357, p = 0.025). There were no differences in TEP peak amplitudes between the groups. Further, DLPFC-CEA was inversely associated with MoCA and SOC, and positively associated with EXIT scores in AD. These results suggest increased DLPFC excitability in AD, and its inverse associations with global cognition and executive function. Future studies should examine these findings in larger samples and longitudinally, and could also assess these markers of cortical excitability in relation to other established markers of AD and in response to interventions.

Long-Acting Injectable Antipsychotic Treatment in Schizophrenia and Co-occurring Substance Use Disorders: A Systematic Review

Objectives: Co-occurring substance use disorders (SUDs) among individuals with schizophrenia are a prevalent and complex psychiatric comorbidity, which is associated with increased symptom severity, worsened illness trajectory and high rates of treatment non-adherence. Recent evidence suggests that the use of long-acting injectable (LAI) antipsychotics may provide an effective treatment option for individuals with this dual-diagnosis. Methods: A systematic review of the literature was conducted using the databases PubMed, PsychInfo and Google Scholar for English-language studies, investigating the use of LAIs in co-occurring schizophrenia and substance use disorders (SCZ-SUDs). Results: Eight reports [one case study (n = 1), one case series (n = 8), three open-label retrospective studies (n = 75), and three randomized controlled trials (n = 273)] investigated the use of LAI antipsychotics in 357 participants with SCZ-SUDs [alcohol use disorder: 5 studies, n = 282; cocaine use disorder: 5 studies, n = 85; amphetamine use disorder: 1 study, n = 1; cannabis use disorder: 3 studies, n = 160; opioid use disorder: 3 studies, n = 19; methylenedioxymethamphetamine (MDMA) use disorder: 2 studies, n = 9; ketamine use disorder: 1 study, n = 4] and were included in this systematic review. Findings indicate significant improvements in substance use related outcomes across 7 of 8 studies, while in 6 of 8 studies, significant improvements in psychopathology-related outcomes were reported. Conclusions: LAI antipsychotics may be an efficacious intervention option for the treatment of SCZ-SUDs. However, varying methodological rigor, generally small sample sizes and heterogeneity of samples, settings, substances of abuse, tested LAIs and comparators, as well as psychosocial cotreatments and level of reported detail across studies requires that these findings be considered preliminary and interpreted with caution. Further research is required to better understand the effects of LAIs among individuals with SCZ-SUDs.

Peripheral cytokine and fatty acid associations with neuroinflammation in AD and aMCI patients: An exploratory study

Neuroinflammation is thought to be important in the progression of Alzheimer's disease (AD). To evaluate cerebral inflammation radioligands that target TSPO, a translocator protein strongly expressed in microglia and macrophages during inflammation, can be used in conjunction with positron emission tomography (PET) imaging. In AD patients, neuroinflammation is up-regulated compared to both healthy volunteers as well as to subjects with amnestic Mild Cognitive Impairment. Peripheral biomarkers, such as serum cytokines and total fatty acids (FAs), can also be indicative of the inflammatory state of subjects with neurodegenerative disorders. To understand whether peripheral biomarkers are predictive of neuroinflammation we conducted a secondary exploratory analysis of two TSPO imaging studies conducted in subjects with AD, aMCI and aged matched healthy volunteers. We examined the association between candidate peripheral biomarkers (including amyloid beta, cytokines and serum total fatty acids) with brain TSPO levels. Our results showed that serum IL-6 and IL-10 are higher in AD compared to the aMCI and healthy volunteers while levels of some fatty acids are modulated during the disease. A limited number of associations were observed between region-specific inflammation and fatty acids in aMCI patients, and between amyloid beta 42 and brain inflammation in AD, however no associations were present with systemic cytokines. Our study suggests that while TSPO binding and systemic IL-6 and IL-10 were elevated in AD, serum amyloid beta, cytokines and fatty acids were generally not predictive of the disease nor correlated with neuroinflammation.

Imaging microglial activation and amyloid burden in amnestic mild cognitive impairment

Amnestic mild cognitive impairment (aMCI) is defined as a transitional state between normal aging and Alzheimer's disease (AD). Given the replicated finding of increased microglial activation in AD, we sought to investigate whether microglial activation is also elevated in aMCI and whether it is related to amyloid beta (Aβ) burden in-vivo . Eleven aMCI participants and 14 healthy volunteers completed positron emission tomography (PET) scans with [¹⁸F]-FEPPA and [¹¹C]-PIB. Given the known sensitivity in affinity of second-generation TSPO radioligands, participants were genotyped for the TSPO polymorphism and only high-affinity binders were included. Dynamic [¹⁸F]-FEPPA PET images were analyzed using the 2-tissue compartment model with arterial plasma input function. Additionally, a supplementary method, the standardized uptake value ratio (SUVR), was explored. [¹¹C]-PIB PET images were analyzed using the Logan graphical method. aMCI participants had significantly higher [¹¹C]-PIB binding in the cortical regions. No significant differences in [¹⁸F]-FEPPA binding were observed between aMCI participants and healthy volunteers. In the aMCI group, [¹⁸F]-FEPPA and [¹¹C]-PIB bindings were correlated in the hippocampus. There were no correlations between our PET measures and cognition. Our findings demonstrate that while Aβ burden is evident in the aMCI stage, microglial activation may not be present.

Voxel level quantification of [11C]CURB, a radioligand for Fatty Acid Amide Hydrolase, using high resolution positron emission tomography

[11C]CURB is a novel irreversible radioligand for imaging fatty acid amide hydrolase in the human brain. In the present work, we validate an algorithm for generating parametric map images of [11C]CURB acquired with a high resolution research tomograph (HRRT) scanner. This algorithm applies the basis function method on an irreversible two-tissue compartment model (k4 = 0) with arterial input function, i.e., BAFPIC. Monte Carlo simulations are employed to assess bias and variability of the binding macroparameters (Ki and λk3) as a function of the voxel noise level and the range of basis functions. The results show that for a [11C]CURB time activity curve with noise levels corresponding to a voxel of an image acquired with the HRRT and reconstructed with the filtered back projection algorithm, the implementation of BAFPIC requires the use of a constant vascular fraction of tissue (5%) and a cutoff for slow frequencies (0.06 min-1). With these settings, BAFPIC maintains the probabilistic distributions of the binding macroparameters with approximately Gaussian shape and minimizes the bias and variability for large physiological ranges of the rate constants of [11C]CURB. BAFPIC reduces the variability of Ki to a third of that given by Patlak plot, the standard graphical method for irreversible radioligands. Application to real data demonstrated an excellent correlation between region of interest and BAFPIC parametric data and agreed with the simulations results. Therefore, BAFPIC with a constant vascular fraction can be used to generate parametric maps of [11C]CURB images acquired with an HRRT provided that the limits of the basis functions are carefully selected.

Molecular imaging of neuroinflammation in Alzheimer's disease and mild cognitive impairment

Neuroinflammatory changes have been demonstrated to be an important feature of Alzheimer's disease (AD); however, the exact role of neuroinflammation and its progression during disease is still not well understood. One of the main drivers of the neuroinflammatory process are microglial cells. Positron Emission Tomography allows for the quantification of microglial activation by labelling the Translocator Protein 18kDa (TSPO), which becomes overexpressed upon activation of microglial cells. Several radioligands have been designed to target TSPO and have been studied in-vivo in AD populations. While most studies have shown important increases in TSPO binding in AD populations compared to healthy volunteers, whether the neuroinflammatory progress occurs early on or later during disease is still unclear. In order to investigate the early changes in neuroinflammation, studies have sought to investigate microglial activation in patients with mild cognitive impairment (MCI), which is defined as a transitional stage between normal aging and dementia. In this prodromal population, conflicting results have been reported with some studies reporting increased binding in MCI, while others demonstrate no differences from controls. Here we review the TSPO PET studies in AD and MCI populations and discuss the important methodological considerations of imaging microglial activation.

Feasibility study of TSPO quantification with [18F]FEPPA using population-based input function

PURPOSE

The input function (IF) is a core element in the quantification of Translocator protein 18 kDa with positron emission tomography (PET), as no suitable reference region with negligible binding has been identified. Arterial blood sampling is indeed needed to create the IF (ASIF). In the present manuscript we study individualization of a population based input function (PBIF) with a single arterial manual sample to estimate total distribution volume (VT) for [18F]FEPPA and to replicate previously published clinical studies in which the ASIF was used.

METHODS

The data of 3 previous [18F]FEPPA studies (39 of healthy controls (HC), 16 patients with Parkinson's disease (PD) and 18 with Alzheimer's disease (AD)) was reanalyzed with the new approach. PBIF was used with the Logan graphical analysis (GA) neglecting the vascular contribution to estimate VT. Time of linearization of the GA was determined with the maximum error criteria. The optimal calibration of the PBIF was determined based on the area under the curve (AUC) of the IF and the agreement range of VT between methods. The shape of the IF between groups was studied while taking into account genotyping of the polymorphism (rs6971).

RESULTS

PBIF scaled with a single value of activity due to unmetabolized radioligand in arterial plasma, calculated as the average of a sample taken at 60 min and a sample taken at 90 min post-injection, yielded a good interval of agreement between methods and optimized the area under the curve of IF. In HC, gray matter VTs estimated by PBIF highly correlated with those using the standard method (r2 = 0.82, p = 0.0001). Bland-Altman plots revealed PBIF slightly underestimates (~1 mL/cm3) VT calculated by ASIF (including a vascular contribution). It was verified that the AUC of the ASIF were independent of genotype and disease (HC, PD, and AD). Previous clinical results were replicated using PBIF but with lower statistical power.

CONCLUSION

A single arterial blood sample taken 75 minute post-injection contains enough information to individualize the IF in the groups of subjects studied; however, the higher variability produced requires an increase in sample size to reach the same effect size.

Role of quantitative gene expression using RT-PCR in the prediction of recurrence risk in resected T1 clear cell renal cell carcinoma (ccRCC)

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Background: Current pathology and clinical methods do not accurately estimate risk of recurrence in all patients with pT1 ccRCC. Quantitative RT-PCR (qPCR) analysis was performed on resected ccRCC tumors to identify genes associated with recurrence that significantly augment current prognostic tools.

Methods: A retrospective observational cohort consisting of 931 patients (434 T1a, 201 T1b, 296 T2/3) with ccRCC was evaluated. All patients underwent nephrectomy between 1985 and 2003 at Cleveland Clinic and had paraffin-embedded tumor blocks. Patients with inherited ccRCC or inadequate follow-up (< 6 months or no recurrence data) were excluded. qPCR analysis of 732 genes was performed on all patients. Cox Proportional Hazards regression models were used to evaluate the association between gene expression and recurrence-free interval (RFI).

Results: 448 genes were significantly (unadj. p < 0.05) associated with RFI, from which 72 genes were carried forward for further study (Rini, ASCO 2010, #4501). Angiogenesis is the strongest among the pathways represented, from which 3 genes (AQP1, NOS3, PPAP2B) were selected for this analysis. Incorporating these 3 genes, a subset of higher risk patients among those classified as low risk by Leibovich criteria was identified. By Leibovich criteria, 85% of the patients in the cohort with pT1 tumors (< 7.0 cm) were identified as low risk - 7% recurrence at 5 years (95% CI: 5%, 9%). Incorporating these 3 genes, 9% of these patients were found to be at increased risk for recurrence - 19% at 5 years (95% CI: 7%, 21%). For the subset of T1a patients (< 4.0 cm), 98.6% were low risk according to the Leibovich criteria - 7% recurrence at 5 years (95% CI: 4%, 10%). Incorporating the 3 genes, 11% of these patients were found to be at increased risk - 20% at 5 years (95% CI: 7%, 31%).

Conclusions: Addition of 3 angiogenesis-related genes to the Leibovich criteria in patients with pT1 tumors refines stratification of patient risk in a subset of patients. More precise estimation of recurrence risk will help to tailor surveillance and refine inclusion into clinical trials. These genes will be incorporated into an algorithm that requires validation in an external data set.

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[Heat thrombosis of burned skin]

The vital reaction to heat-induced thrombosis is discussed here using a case of sudden death in the Sauna. The dead body was lying for about one hour in the heat (90 degrees C). Beside the beginning formation of bubbles there was subcutaneous blood vessel exposition, especially in parts outside of the Livor mortis. The cause of death was viral infection with florid Myocarditis.