Risk Factors for Late-Onset Psychosis: A Case-Control Study.

BACKGROUND AND HYPOTHESIS: The onset of schizophrenia occurs after the age of 40 in up to 20% of cases. We aim to depict risk factors for first-episode psychosis after the age of 40 by comparing late-onset psychosis (LOP) patients to healthy age-matched controls. STUDY DESIGN: In this case-control study using electronic health records, 142 individuals aged 40-65 years with an encounter for a first episode of psychosis between 2013 and 2021 were included. Four controls (N = 568) were matched to each case on age, sex, race, and year of encounter. Potential risk factors for the primary analysis were captured via structured data and text-mining of medical notes. Conditional logistic regression models were used to assess the odds of LOP with potential risk factors. STUDY RESULTS: After adjusting for all variables in the main analysis, odds for LOP were increased by immigration (OR 3.30, 95% CI, 1.56-6.98), depression (OR 3.58, 95% CI, 2.01-6.38), anxiety (OR 2.12, 95% CI, 1.20-3.75), cannabis use (OR 3.00, 95% CI, 1.36-6.61), alcohol use disorder (OR 5.46, 95% CI, 2.41-12.36), polysubstance use (OR 4.22, 95% CI, 1.30-13.7), severe trauma (OR 2.29, 95% CI, 1.08-4.48), and caregiver burden (OR 15.26, 95% CI, 3.85-60.48). CONCLUSIONS: Life stressors along with the effects of substance use and other psychiatric conditions may confer some risk to the development of LOP. Replication is required in independent prospective studies. Further research is necessary to truly parse out which of these factors belong on the causal pathway.

Risk of Incident Psychosis and Mania With Prescription Amphetamines.

OBJECTIVE: Amphetamine prescribing has increased in the United States in recent years. Previous research identified an increased risk of incident psychosis with prescription amphetamines. The purpose of this study was to examine the impact of dose levels of prescription amphetamines on the risk of this rare but serious adverse outcome. METHODS: A case-control study using electronic health records was conducted to compare the odds of incident psychosis or mania with past-month exposure to prescription amphetamines. Case subjects were patients ages 16-35 hospitalized at McLean Hospital for incident psychosis or mania between 2005 and 2019. Control subjects were patients with an initial psychiatric hospitalization for other reasons, most commonly depression and/or anxiety. Amphetamine doses were converted to dextroamphetamine equivalents and divided into terciles. Secondary analyses evaluated the odds of psychosis or mania with methylphenidate use. RESULTS: Among 1,374 case subjects and 2,748 control subjects, the odds of psychosis and mania were increased for individuals with past-month prescription amphetamine use compared with no use (adjusted odds ratio=2.68, 95% CI=1.90-3.77). A dose-response relationship was observed; high doses of amphetamines (>30 mg dextroamphetamine equivalents) were associated with 5.28-fold increased odds of psychosis or mania. Past-month methylphenidate use was not associated with increased odds of psychosis or mania compared with no use (adjusted odds ratio=0.91, 95% CI=0.54-1.55). CONCLUSIONS: Although use of hospitalized control subjects excludes individuals with less severe disease, leading to selection bias, the study results suggest that caution should be exercised when prescribing high doses of amphetamines, with regular screening for symptoms of psychosis or mania.

Identifying Psychosis Episodes in Psychiatric Admission Notes via Rule-based Methods, Machine Learning, and Pre-Trained Language Models.

Early and accurate diagnosis is crucial for effective treatment and improved outcomes, yet identifying psychotic episodes presents significant challenges due to its complex nature and the varied presentation of symptoms among individuals. One of the primary difficulties lies in the underreporting and underdiagnosis of psychosis, compounded by the stigma surrounding mental health and the individuals' often diminished insight into their condition. Existing efforts leveraging Electronic Health Records (EHRs) to retrospectively identify psychosis typically rely on structured data, such as medical codes and patient demographics, which frequently lack essential information. Addressing these challenges, our study leverages Natural Language Processing (NLP) algorithms to analyze psychiatric admission notes for the diagnosis of psychosis, providing a detailed evaluation of rule-based algorithms, machine learning models, and pre-trained language models. Additionally, the study investigates the effectiveness of employing keywords to streamline extensive note data before training and evaluating the models. Analyzing 4,617 initial psychiatric admission notes (1,196 cases of psychosis versus 3,433 controls) from 2005 to 2019, we discovered that the XGBoost classifier employing Term Frequency-Inverse Document Frequency (TF-IDF) features derived from notes pre-selected by expert-curated keywords, attained the highest performance with an F1 score of 0.8881 (AUROC [95% CI]: 0.9725 [0.9717, 0.9733]). BlueBERT demonstrated comparable efficacy an F1 score of 0.8841 (AUROC [95% CI]: 0.97 [0.9580, 0.9820]) on the same set of notes. Both models markedly outperformed traditional International Classification of Diseases (ICD) code-based detection methods from discharge summaries, which had an F1 score of 0.7608, thus improving the margin by 0.12. Furthermore, our findings indicate that keyword pre-selection markedly enhances the performance of both machine learning and pre-trained language models. This study illustrates the potential of NLP techniques to improve psychosis detection within admission notes and aims to serve as a foundational reference for future research on applying NLP for psychosis identification in EHR notes.

Persistent effects of COVID-19 in patients hospitalized during the first wave of the pandemic: The impact of persistent fatigue on quality of life in a cross-sectional study.

COVID-19 can affect physical and mental health long after acute infection. In this descriptive study, 48 individuals hospitalized for COVID-19 between April and May 2020 were interviewed regarding their experience with COVID-19 after hospitalization. The mean age of participants was 51.1 (±11.91) years (range 25-65 years) and 26 (54.2%) were men. Individuals had a mean of 1.2 (±0.94) comorbidities associated with more severe COVID-19, with hypertension (37.5%) being most common. Nineteen (39.6%) individuals required treatment in the intensive care unit. Participants were interviewed a median time of 553 days (IQR, 405.5-589.0) after discharge from the hospital. Thirty-seven (77.1%) individuals had 5 or more persistent symptoms at time of interview with only 3 (6.3%) experiencing none. The most reported persistent symptoms were fatigue (79.2%), difficulty breathing (68.8%), and muscle weakness (60.4%). Poor quality of life was experienced by 39 (81.3%) participants and 8 (16.7%) had a posttraumatic stress disorder (PTSD) score within the clinical range for diagnosis. For multivariable analyses, persistent fatigue was significantly predicted by number of symptoms during acute COVID-19 (t = 4.4, p < 0.001). Number of symptoms during acute COVID-19 was also significantly associated with persistent dyspnea (t = 3.4, p = 0.002). Higher scores on the Chalder fatigue scale after COVID-19 was significantly associated with poor quality of life (t = 2.6, p = 0.01) and PTSD symptomatology (t = 2.9, p = 0.008). More research is needed to highlight the wide range of resources those suffering from Long COVID require long after discharge.

Rapid single-molecule imaging in cyclic olefin copolymer channels.

Rapid preparation of high quality capture surfaces is a major challenge for surface-based single-molecule protein binding assays. Here we introduce a simple method to activate microfluidic chambers made from cyclic olefin copolymer for single-molecule imaging with total internal reflection fluorescence microscopy. We describe a surface coating protocol and demonstrate single-molecule imaging in off-the-shelf microfluidic parts that can be activated for binding assays within a few minutes. As the first example, biotinylated protein directly captured on the neutravidin-coated surface was detected using fluorescently labeled antibody. We then showed detection of a fusion construct containing green fluorescence protein and verified its single fluorophore behavior by observing stepwise photobleaching events. Finally, a target protein was identified in the crude cell lysate using antibody-sandwich complex formation. In all experiments, controls were completed to ensure that nonspecific binding to the surface was minimal. Based on our results, we conclude that the simple surface preparation described in this paper enables single-molecule imaging assays without time-consuming coating procedures.

Affinity assisted selection of antibodies for Point of Care TSH immunoassay with limited wash.

BACKGROUND: Molecular binding characteristics of several thyroid stimulating hormone (TSH) antibodies were determined for the TSH antigen, along with its closely related endogenous interfering hormones, follicle stimulating hormone (FSH), luteinizing hormone (LH) and chorionic gonadotropin (CG). METHODS: This data was compared to the same antibodies used in the low wash sandwich ELISA immunoassay system, the Point of Care i-STAT® immunoassay. From this information we developed binding criteria useful in the low wash i-STAT® immunoassay to permit good signal generation from TSH and low cross-reactivity from its interfering hormones. For the TSH Assay we have developed characteristics that enable antibody selection in the i-STAT® immunoassay cartridge. Our antibody screening approach used a dot blot approach as a first screen to select for the most useful antibodies. We then compared a FRET (Förster Resonance Energy Transfer) and electrochemical cartridge approach to determine the appropriate antibody combinations. RESULTS: Both methods generated similar data, but the FRET method was not capable of differentiating the antibody with the best characteristics as a capture antibody or a detection conjugate in a sandwich ELISA assay. Finally, we performed binding characterizations of the antibodies using each of the above mentioned glycoproteins. CONCLUSIONS: We found that we need sub-picomolar detection of TSH, and at least 100 fold or higher values for the cross-reacting species.

Simplified confocal microscope for counting particles at low concentrations.

We describe a compact scanning confocal fluorescence microscope capable of detecting particles concentrations less than 100 particles∕ml in ~15 min. The system mechanically moves a cuvette containing ~3 ml of sample. A relatively large confocal volume is observed within the cuvette using a 1 mm pinhole in front of a detection PMT. Due to the motion of the sample, particles traverse the confocal volume quickly, and analysis by pattern recognition qualifies spikes in the emission intensity data and counts them as events. We show linearity of detection as a function of concentration and also characterize statistical behavior of the instrument. We calculate a detection sensitivity of the system using 3 µm fluorescent microspheres to be 5 particles/ml. Furthermore, to demonstrate biological application, we performed a dilution series to quantify stained E. coli and yeast cells. We counted E. coli cells at a concentration as low as 30 cells∕ml in 10 min/sample.

Studying antibody-antigen interactions with fluorescence fluctuation spectroscopy.

Antibodies are excellent binding proteins that have found numerous applications in biological research, biotechnology, and medicine. Characterization of their ligand binding properties has long been, and continues to be, the focus of many researchers. Antibodies are also perfect test systems which can be used for the evaluation of newly introduced biophysical techniques. Working with many different antibodies, we continuously implement the growing arsenal of methods offered by fluorescence fluctuation spectroscopy (FFS) and apply them for antibody research. In this chapter, we will describe applications of FFS for antibody binding characterization and also provide examples how studying of antibodies helps to develop and enhance the tool set offered by FFS technology. In addition to traditional affinity evaluations, we will describe how resolving molecular populations enables determinations of the binding stoichiometry and provides further information about the system. Even though all our examples include antibodies, the same experimental procedures can also serve well for characterizing various proteins and other ligand binding systems.

Introduction of the mass spread function for characterization of protein conjugates.

Traditionally, characterization of protein molecules conjugated with molecular probes is performed by UV-vis spectroscopy. This method determines the average incorporation ratio but does not yield information about the label distribution. Electrospray ionization mass spectroscopy (ESI-MS) allows direct measurement of the fraction of protein containing a given number of labels. However, for a glycosylated protein, this analysis can be severely limited due to spectral overlap of the labels and carbohydrates. To address this problem, we introduce the mass spread function (MSF) for conjugation analysis. By treating the ESI-MS spectrum of conjugated protein as the spectrum before conjugation convolved with the MSF, we are able to quantify the labeled protein population using a binomial distribution function. We first applied this procedure for characterization of labeled antibody F(ab')(2) fragments which do not contain carbohydrates. We then apply the MSF to fit spectra of entire conjugated monoclonal antibodies and quantify the distribution of labels in the presence of glycans.

Determining antibody stoichiometry using time-integrated fluorescence cumulant analysis.

We applied fluorescence fluctuation spectroscopy to resolve the binding heterogeneity of fluorescently labeled ligand derived from brain natriuretic peptide (BNP), a widely used diagnostic marker of heart failure, to a corresponding monoclonal antibody. This system includes three species: (1) free ligand molecules, (2) antibody with a single site occupied, and (3) antibody with both sites occupied. The method we used, time-integrated fluorescence cumulant analysis (TIFCA), utilizes cumulants of fluorescence fluctuations to resolve subpopulations of multiple fluorescent species freely diffusing in a solution. The values of the cumulants depend on the concentration, molecular brightness and diffusion time of the fluorescent molecules. The number of molecules in each species reflects the antibody affinity. We apply TIFCA to successfully establish the stoichiometry of the system, estimate affinity, and identify the presence of an inactive fraction of antigen in a single titration experiment.

Using nonfluorescent Förster resonance energy transfer acceptors in protein binding studies.

The purpose of this article is to highlight the versatility of nonfluorescent Förster resonance energy transfer (FRET) acceptors in determination of protein equilibrium dissociation constants and kinetic rates. Using a nonfluorescent acceptor eliminates the necessity to spectrally isolate the donor fluorescence when performing binding titrations covering a broad range of reagent concentrations. Moreover, random distribution of the donor and acceptor chromophores on the surface of proteins increases the probability of FRET occurring on their interaction. Three high-affinity antibodies are presented in this study as characteristic protein systems. Monoclonal antibody (mAb) 106.3 binds brain natriuretic peptide (BNP)5-13(C10A) and full-length BNP1-32 with the dissociation constants 0.26+/-0.01 and 0.05+/-0.02 nM, respectively, which was confirmed by kinetic measurements. For anti-hCG (human chorionic gonadotropin) mAb 8F11, studied at two incorporation ratios (IRs=1.9 and 3.8) of the nonfluorescent FRET acceptor, K(D) values of 0.04+/-0.02 and 0.059(-0.004)(+0.006) nM, respectively, were obtained. Likewise, the binding of goat anti-hamster immunoglobulin G (IgG) antibody was not affected by conjugation and yielded K(D) values of 1.26+/-0.04, 1.25+/-0.05, and 1.14+/-0.04 nM at IRs of 1.7, 4.7, and 8.1, respectively. We conclude that this FRET-based method offers high sensitivity, practical simplicity, and versatility in protein binding studies.

Fluorescence fluctuation spectroscopy in the presence of immobile fluorophores.

Fluorescence contributions from immobile sources present a challenge for fluorescence fluctuation spectroscopy (FFS) because the absence of signal fluctuations from stationary fluorophores leads to a biased analysis. This is especially of concern for cellular FFS studies on proteins that interact with immobile structures. Here we present a method that correctly analyzes FFS experiments in the presence of immobile sources by exploiting selective photobleaching of immobile fluorophores. The fluorescence decay due to photobleaching of the immobile species is modeled taking into account the nonuniform illumination volume. The experimentally observed decay curve serves to separate the mobile and immobile fluorescence contribution, which is used to calculate the molecular brightness from the FFS data. We experimentally verify this approach in vitro using the fluorescent protein EGFP as our immobilized species and a diffusing dye of a different color as the mobile one. For this special case, we also use an alternative method of determining the brightness by spectrally resolving the two species. By conducting a dilution study, we show that the correct parameters are obtained using either technique for a wide range of mobile fractions. To demonstrate the application of our technique in living cells, we perform experiments using the histone core protein H2B fused with EGFP expressed in COS-1 cells. We successfully recovered the brightness of the mobile fraction of H2B-EGFP.

Probing nucleocytoplasmic transport by two-photon activation of PA-GFP.

Two-photon activation of photoactivatable green fluorescent protein (PA-GFP) provides a unique tool for probing cellular transport processes, because activation is strictly limited to the sub-femtoliter optical volume of the two-photon spot. We demonstrate two-photon activation of PA-GFP immobilized in a gel and freely diffusing within cells and recover a quadratic power dependence. Illumination at 820 nm allows simultaneous activation and fluorescence monitoring by two-photon excitation. Alternatively, we activate PA-GFP using two-photon excitation and monitor the fluorescence of the photoconverted product with one-photon excitation. We probe nucleocytoplasmic transport through the nuclear pore complex of COS-1 cells, by observing the time-dependent fluorescence at various locations within the cell after two-photon activation of PA-GFP in the nucleus and in the cytoplasm. Two-photon activation of a tandem construct of two PA-GFPs showed a markedly slower rate of crossing through the nuclear pore. Analysis based on a restricted diffusion model yields a nuclear pore radius of 4.5 nm, which is in good agreement with previously reported values. This application demonstrates the attractive features of two-photon photoactivation over traditional techniques, such as photobleaching, for studying transport processes in cells.

Position-sensitive scanning fluorescence correlation spectroscopy.

Fluorescence correlation spectroscopy (FCS) uses a stationary laser beam to illuminate a small sample volume and analyze the temporal behavior of the fluorescence fluctuations within the stationary observation volume. In contrast, scanning FCS (SFCS) collects the fluorescence signal from a moving observation volume by scanning the laser beam. The fluctuations now contain both temporal and spatial information about the sample. To access the spatial information we synchronize scanning and data acquisition. Synchronization allows us to evaluate correlations for every position along the scanned trajectory. We use a circular scan trajectory in this study. Because the scan radius is constant, the phase angle is sufficient to characterize the position of the beam. We introduce position-sensitive SFCS (PSFCS), where correlations are calculated as a function of lag time and phase. We present the theory of PSFCS and derive expressions for diffusion, diffusion in the presence of flow, and for immobilization. To test PSFCS we compare experimental data with theory. We determine the direction and speed of a flowing dye solution and the position of an immobilized particle. To demonstrate the feasibility of the technique for applications in living cells we present data of enhanced green fluorescent protein measured in the nucleus of COS cells.