Interocular Symmetry in Retinal Nerve Fiber Layer Thickness in Children: The Hong Kong Children Eye Study.

INTRODUCTION: The aim of this work is to determine the interocular differences in peripapillary retinal nerve fiber layer (p-RNFL) thickness and its associations among school children in Hong Kong. METHODS: We conducted a population-based study including 4034 children aged 6-8 years from the Hong Kong Children Eye Study (HKCES). All participants received comprehensive ocular examinations where p-RNFL thickness was measured using spectral-domain optical coherence tomography (SD-OCT). The degree of symmetry between both eyes was analyzed and represented by intraclass correlation coefficient (ICC) values. Multivariable linear regression analysis was used to investigate the associations between ocular and systemic factors with p-RNFL thickness difference. RESULTS: The study included 4034 children with a mean age of 7.61 ± 0.98 years. The mean global p-RNFL thickness was 106.60 ± 9.41 µm in right eyes and 105.99 ± 9.30 µm in left eyes. The ICC for global p-RNFL difference was 0.866 (95% CI 0.858-0.873, p < 0.001). The symmetry displayed the largest values in nasal inferior quadrant with the ICC value of 0.736 (95% CI 0.721-0.749); and the smallest degree of symmetry was found to be in the superior temporal quadrant with the ICC value of 0.567 (95% CI 0.546-0.588). Axial length (AL) difference was found to have more pronounced correlation to interocular symmetry in p-RNFL thickness with the coefficient of 0.514 (p < 0.001). CONCLUSIONS: Normal variation in interocular symmetry exists in children. Our results can contribute to the establishment of a standard reference for interocular differences in OCT parameters in children. The interocular differences in AL should be considered in the interpretation of RNFL symmetry, in terms of identifying children at risk of developing glaucoma or other ocular disorders.

Influence of secondhand smoke exposure on the retinal vasculature of children in Hong Kong.

BACKGROUND: A recent prospective demonstrated that cardiovascular risk factors in early childhood were associated with later cardiovascular events. However, the impact of secondhand smoke (SHS) on children is unclear. The aims of this study is to determine the effects of SHS exposure on the retinal vasculature of children. METHODS: This is a population-based cross-sectional study of children aged 6 to 8 years. All participants received comprehensive ophthalmic examinations and retinal photography. Data on SHS exposure was derived from a validated questionnaire. A validated deep-learning system was used to automatically estimate retinal arteriolar and venular calibers from retinal photographs. Associations of quantitative retinal vessel caliber values with SHS exposure, number of smokers in the household, and total number of cigarettes smoked were determined by analyses of covariance (ANCOVA) after adjusting for potential confounders. Test of trend was determined by treating categorical risk factors as continuous ordinal variables. RESULTS: Here we show children exposed to SHS have wider retinal arteriolar (CRAE 152.1 µm vs. 151.3 µm, p < 0.001) and venular (CRVE 216.7 µm vs. 215.5 µm, p < 0.001) calibers compared to those in smoke-free homes, after adjustment for different factors. Wider arteriolar and venular calibers are also associated with increasing number of smokers in the family (p trend < 0.001) and more cigarettes smoked among family smokers (p trend<0.001). CONCLUSIONS: Exposure to SHS at home is associated with changes in retinal vasculature among children. This reinforces the adverse effect of secondhand smoking around children though further research incorporating comprehensive assessment of potential confounders is necessary.

Exposure to secondhand smoke can be harmful, particularly for our heart and lung health as adults. However, the impact of secondhand smoke on children is less clear. Here, we looked at the effects of secondhand smoke exposure on vessels within children's eyes. The health of these vessels is a potential indicator of overall eye health and is also associated with cardiovascular disease. Pictures were taken of children's eyes and analyzed using a computer program. We looked at the association between vessel measurements in the eye and how much secondhand smoke the children are exposed to. We observed differences in the vessels in children exposed to secondhand smoke, compared to those from smoke-free homes. These findings indicate that secondhand smoke may affect the health of children's eyes and highlight the need to promote smoke-free home environments.

Multifunctional theranostic carbazole-based cyanine for real-time imaging of amyloid-ß and therapeutic treatment of multiple pathologies in Alzheimer's disease.

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder characterized by the synaptic and neuronal loss, which results in cognitive impairment in particular learning and memory. Currently, AD is incurable and no single confirmative test can clinically be used to diagnose AD. In light of the complex and multifactorial nature of AD etiology, the development of multifunctional/multi-target drugs that act on multiple pathological pathways and mechanisms shows great therapeutic potential for intervention of this devastating disease. We report herein a multifunctional theranostic cyanine, SLCOOH, which serves not only as a highly sensitive fluorescent probe for real-time imaging of amyloid-ß (Aß) contents in different age groups of transgenic (Tg) AD mice but also as an effective therapeutic agent for early AD intervention via multiple pathological targets in the AD mouse model. Remarkably, treatment with SLCOOH gives rise to multiple therapeutic benefits, including the amelioration of cognitive decline, a reduction in Aß levels, a decrease in hyperphosphorylated tau proteins and tau depositions, and the alleviation of synaptic loss and dysfunctions in young triple Tg AD mice. Our results have demonstrated that in addition to superior Aß imaging capability, SLCOOH exhibits versatile and effective multiple modes of drug action, signifying outstanding therapeutic potential to treat early onset AD. Our work also paves the way for the development of effective Aß-targeted theranostic agents for AD.

Prevalence and Characteristics of Peripapillary Gamma Zone in Children With Different Refractive Status: The Hong Kong Children Eye Study.

Purpose: This study aimed to assess the prevalence and characteristics of the peripapillary gamma zone in myopic, emmetropic, and hyperopic eyes of Chinese children. Methods: Overall, 1274 children aged 6 to 8 years from the Hong Kong Children Eye Study underwent ocular examinations, including measurements of cycloplegic auto-refraction and axial length (AL). The optic disc was imaged using a Spectralis optical coherence tomography (OCT) unit and a protocol involving 24 equally spaced radial B-scans. The Bruch's membrane opening (BMO) was identified in over 48 meridians in each eye. The peripapillary gamma zone was defined as the region between the BMO and the border of the optic disc, identified by the OCT. Results: The prevalence of the peripapillary gamma zone was higher in myopic eyes (36.3%) than in emmetropic (16.1%) and hyperopic eyes (11.5%, P < 0.001). AL (per 1 mm; odds ratio [OR]) = 1.861, P < 0.001) and a more oval disc shape (OR = 3.144, P < 0.001) were associated with the presence of a peripapillary gamma zone after adjusting for demographic, systemic, and ocular variables. In the subgroup analysis, a longer AL was associated with the presence of a peripapillary gamma zone in myopic eyes (OR = 1.874, P < 0.001), but not in emmetropic (OR = 1.033, P = 0.913) or hyperopic eyes (OR = 1.044, P = 0.883). A peripapillary zone was not observed in the region nasal to the optic nerve in myopic eyes, in contrast to its presence in the same region in 1.9% of emmetropic eyes and 9.3% of hyperopic eyes; these intergroup differences were statistically significant (P < 0.001). Conclusions: Although peripapillary gamma zones were observed in the eyes of both myopic and non-myopic children, their characteristics and distribution patterns were substantially different.

Effect of Myopic Undercorrection on Habitual Reading Distance in Schoolchildren: The Hong Kong Children Eye Study.

INTRODUCTION: This study aimed to evaluate the habitual reading distance among non-myopic children and also myopic children with undercorrection and with full correction. METHODS: This was a population-based cross-sectional study with a total of 2363 children aged 6-8 years who were recruited from the Hong Kong Children Eye Study. Cycloplegic autorefraction, subjective refraction, habitual visual acuity, and best corrected visual acuity were measured. The entire reading process (9 min) was recorded using a hidden video camera placed 5 m away from the reading desk. Reading distances were taken at 6, 7, 8, and 9 min after the child began reading and were measured using a customized computer program developed in MATLAB. The main outcome was the association of habitual reading distances with refraction status. Habitual reading distances of children were documented via video camera footage. RESULTS: The habitual reading distances of undercorrected myopic children (23.37 ± 4.31 cm) were the shortest when compared to non-myopic children (24.20 ± 4.73 cm, P = 0.002) and fully corrected myopic children (24.81 ± 5.21 cm, P < 0.001), while there was no significant difference between the last two children groups (P = 0.17). A shorter reading distance was associated with myopia (OR 1.67; 95% CI 1.11-2.51; P = 0.013) after adjusting for age, sex, height, near work time, outdoor time, and parental myopia. The association of reading distance with myopia did not hold after undercorrected myopic children were excluded (OR 0.97, 95% CI 0.55-1.73; P = 0.92). A shorter reading distance correlated with poorer vision under habitual correction (ß = - 0.003, P < 0.001). CONCLUSION: A shorter reading distance was present among undercorrected myopic children. Myopia undercorrection is not recommended as a strategy for slowing myopic progression.

Increase in Bruch's membrane opening minimum rim width with age in healthy children: the Hong Kong Children Eye Study.

BACKGROUND/AIMS: To identify normative values and determinants for Bruch's membrane opening (BMO) and the minimum rim width of BMO (BMO-MRW) among healthy children. METHODS: A population-based cross-sectional study from the Hong Kong Children Eye Study, recruiting 1, 226 children aged 6-8 years. Spherical refractive error, axial length (AL), body mass index and intraocular pressure (IOP) were measured. The optic nerve head and the peripapillary retinal nerve fibre layer (p-RNFL) were imaged through spectral domain-optical coherence tomography, using 24 equally spaced radial B-scans. Global and sectoral BMO-MRW values, BMO area and fovea-to-BMO (FoBMO) angle were calculated. Multiple regression analysis was performed to define the determinants of BMO area and BMO-MRW in relation to demographic and ocular parameters. RESULTS: The mean values for global BMO-MRW, BMO area and FoBMO angle among children were 345.76±54.08 µm, 2.34±0.49 mm2 and -5.45±4.36°, respectively. Global and sectoral values for BMO-MRW correlated with p-RNFL thickness (r=0.11-0.35, p<0.001). After adjusting for demographic and ocular parameters, global BMO-MRW increased with age (ß=6.4, p<0.001) and greater global p-RNFL thickness (ß=1.41, p<0.001), but decreased with larger BMO area (ß=-47.46, p<0.001) and higher IOP (ß=-1.73, p<0.001). Global BMO-MRW did not associate with AL, whereas both BMO area and FoBMO angle associated with AL (ß=0.04, p=0.02 and ß=0.31, p=0.03, respectively), but not with age. CONCLUSION: We observed that BMO-MRW increases with age among children. Our results provide normative values and the determinants of BMO parameters among Chinese children.

Vitamin D and Ocular Diseases: A Systematic Review.

The contributory roles of vitamin D in ocular and visual health have long been discussed, with numerous studies pointing to the adverse effects of vitamin D deficiency. In this paper, we provide a systematic review of recent findings on the association between vitamin D and different ocular diseases, including myopia, age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), dry eye syndrome (DES), thyroid eye disease (TED), uveitis, retinoblastoma (RB), cataract, and others, from epidemiological, clinical and basic studies, and briefly discuss vitamin D metabolism in the eye. We searched two research databases for articles examining the association between vitamin D deficiency and different ocular diseases. One hundred and sixty-two studies were found. There is evidence on the association between vitamin D and myopia, AMD, DR, and DES. Overall, 17 out of 27 studies reported an association between vitamin D and AMD, while 48 out of 54 studies reported that vitamin D was associated with DR, and 25 out of 27 studies reported an association between vitamin D and DES. However, the available evidence for the association with other ocular diseases, such as glaucoma, TED, and RB, remains limited.

Thicker Retinal Nerve Fiber Layer with Age among Schoolchildren: The Hong Kong Children Eye Study.

This study aims to investigate the effect of age on the peripapillary retinal nerve fiber layer (p-RNFL) thickness among schoolchildren. A total of 4034 children aged 6-8 years old received comprehensive ophthalmological examinations. p-RNFL thickness was measured from a circular scan (⌀ = 3.4 mm) captured using spectral-domain optical coherence tomography (SD-OCT). Associations between p-RNFL thickness with ocular and systemic factors were determined by multivariate linear regression after adjusting potential confounders using generalized estimating equations (GEE). The mean global p-RNFL thickness was 106.60 ± 9.41 µm (range: 72 to 171 µm) in the right eyes, 105.99 ± 9.30 µm (range: 76 to 163 µm) in the left eyes, and 106.29 ± 9.36 µm (range: 72 to 171 µm) across both eyes. Age was positively correlated with p-RNFL after adjusting for axial length (AL) and confounding factors (ß = 0.509; p = 0.001). Upon multivariable analysis, AL was positively associated with temporal p-RNFL thickness (ß = 3.186, p < 0.001) but negatively with non-temporal p-RNFL thickness (ß = (10.003, -2.294), p < 0.001). Sectoral p-RNFL was the thickest in the inferior temporal region (155.12 ± 19.42 µm, range 68 to 271 µm), followed by the superior temporal region (154.67 ± 19.99 µm, range 32 to 177 µm). To conclude, p-RNFL increased significantly with older age among children 6 to 8 years old in a converse trend compared to adults. Our results provide a reference for interpreting OCT information in children and suggest that stable p-RNFL thickness may not indicate a stable disease status in pediatric patients due to the age effects.

Myopia incidence and lifestyle changes among school children during the COVID-19 pandemic: a population-based prospective study.

BACKGROUND: The impacts of social restrictions for COVID-19 on children's vision and lifestyle remain unknown. AIMS: To investigate myopia incidence, spherical equivalent refraction (SER) and lifestyle changes among schoolchildren during the COVID-19 pandemic. METHODS: Two separate longitudinal cohorts of children aged 6-8 years in Hong Kong were included. The COVID-19 cohort was recruited at the beginning of the COVID-19 outbreak, whereas the pre-COVID-19 cohort was recruited before the COVID-19 pandemic. All children received ocular examinations, and answered a standardised questionnaire relating to their lifestyle, including time spent on outdoor activities and near work, both at baseline and at follow-up visits. RESULTS: A total of 1793 subjects were recruited, of whom 709 children comprised the COVID-19 cohort with 7.89±2.30 months of follow-up, and 1084 children comprised the pre-COVID-19 cohort with 37.54±3.12 months of follow-up. The overall incidence was 19.44% in the COVID-19 cohort, and 36.57% in pre-COVID-19 cohort. During the COVID-19 pandemic, the change in SER and axial length was -0.50±0.51 D and 0.29±0.35 mm, respectively; the time spent on outdoor activities decreased from 1.27±1.12 to 0.41±0.90 hours/day (p<0.001), while screen time increased from 2.45±2.32 to 6.89±4.42 hours/day (p<0.001). CONCLUSIONS: We showed a potential increase in myopia incidence, significant decrease in outdoor time and increase in screen time among schoolchildren in Hong Kong during the COVID-19 pandemic. Our results serve to warn eye care professionals, and also policy makers, educators and parents, that collective efforts are needed to prevent childhood myopia-a potential public health crisis as a result of COVID-19.

The Association of Choroidal Thickening by Atropine With Treatment Effects for Myopia: Two-Year Clinical Trial of the Low-concentration Atropine for Myopia Progression (LAMP) Study.

PURPOSE: To evaluate longitudinal changes in subfoveal choroidal thickness (SFChT) among children receiving atropine 0.05%, 0.025%, or 0.01% over 2 years and their associations with treatment outcomes in myopia control. DESIGN: Double-blinded randomized controlled trial. METHODS: SFChT was measured at 4-month intervals using spectral domain optical coherence tomography. Cycloplegic spherical equivalent (SE), axial length (AL), best-corrected visual acuity, parental SE, outdoor time, near work diopter hours, and treatment compliance were also measured. RESULTS: 314 children were included with qualified choroidal data. The 2-year changes in SFChT from baseline were 21.15 ± 32.99 µm, 3.34 ± 25.30 µm, and -0.30 ± 27.15 µm for the atropine 0.05%, 0.025%, and 0.01% groups, respectively (P < .001). A concentration-dependent response was observed, with thicker choroids at higher atropine concentrations (ß = 0.89, P < .001). Mean SFChT thickness significantly increased at 4 months in the atropine 0.025% (P = .001) and 0.05% groups (P < .001) and then remained stable until the end of the second year (P > .05 for all groups). Over 2 years, an increase in SFChT was associated with slower SE progression (ß = 0.074, P < .001) and reduced AL elongation (ß = -0.045, P < .001). In the mediation analysis, 18.45% of the effect on SE progression from atropine 0.05% was mediated via its choroidal thickening. CONCLUSIONS: Low concentration atropine induced a choroidal thickening effect along a concentration-dependent response throughout the treatment period. The choroidal thickening was associated with a slower SE progression and AL elongation among all the treatment groups. Choroidal response can be used for assessment of long-term treatment outcomes and as a guide for concentration titrations of atropine.

Saccharide-Functionalized Poly(Zn-salphen)-alt-(m- and p-phenyleneethynylene)s as Dynamic Helical Metallopolymers.

The study of metallopolymers with controllable helical sense remains in its infancy. We report arabinose-functionalized (Zn-salphen)-based conjugated polymers that display mirror-image circular dichroism spectra for L- and D-sugar sidechains respectively, signifying ordered (helical) coiling of the polymer backbone with opposite screw-sense preferences. The observation of different spectroscopic behavior and Cotton effects for a variety of solvents (in a reversible manner) and temperatures, ascribed to changes in the extent of intrachain (Zn⋅⋅⋅O(salphen) and π-stacking) interactions between Zn-salphen moieties, thus indicate the flexible, responsive and dynamic nature of the folded helical conformation in these systems. An application study signifying that activity can be governed by the structure and helical sense of the polymer is described.

Multimodal Theranostic Cyanine-Conjugated Gadolinium(III) Complex for In Vivo Imaging of Amyloid-ß in an Alzheimer's Disease Mouse Model.

Despite the wide use of magnetic resonance imaging (MRI) as a clinical diagnostic tool, there are still no clinically approved MRI contrast agents that can be applied for cerebral Alzheimer's disease (AD) biomarker imaging. We report here the design and development of the first amyloid-ß (Aß)-targeted, blood-brain barrier (BBB) penetrable theranostic Gd(DOTA)-cyanine dyad, which was synthesized by the conjugation of Gd(DOTA) complex and carbazole-based cyanine dye by the copper(I)-catalyzed azide-alkyne cycloaddition click reaction for imaging of Aß in vivo and ex vivo in AD mouse models. This dyad, as a multimodal probe, possesses desirable multifunctional properties, including good biocompatibility, low cytotoxicity, high Aß selectivity, strong fluorescence enhancement upon binding with Aß species, good paramagnetic properties, high stability, good BBB penetrability, and fast elimination from the mouse. The longitudinal relaxivity (r1) of the dyad was found to be 4.42 mM-1 s-1 at 3 T, suggesting it to be promising as a T1-weighted MRI contrast agent. The probe has been successfully demonstrated to be able to be applied for one- and two-photon excited fluorescence and magnetic resonance (MR) imaging of Aß in transgenic mouse models of AD. In addition, it can inhibit Aß aggregation, protect against toxicity induced by Aß, and suppress Aß-induced reactive oxygen species (ROS) production. Our results demonstrate the highly promising theranostic capability of the dyad for diagnosis and therapy of AD and extraordinary potential for MRI of Aß in humans.

Amyloid-ß oligomer targeted theranostic probes for in vivo NIR imaging and inhibition of self-aggregation and amyloid-ß induced ROS generation.

To enable the early detection and intervention of Alzheimer's disease (AD), it is highly desirable to develop novel theranostic agents for simultaneous detection of toxic and pathogenic amyloid-ß (Aß) oligomers in vivo and attenuation of Aß-induced toxicity. Herein, we report a new series of oligomeric Aß targeted near infrared (NIR) emissive dibutylnaphthylamine-based cyanine probes for in vivo and ex vivo imaging of Aß in AD mouse model. These new fluorophores exhibited strong solvatochromism and a large bathochromic shift of the emission spectrum upon binding with Aß species, giving rise to advantageous NIR emission. Besides, they showed an intriguingly stronger fluorescence enhancement upon interacting with Aß oligomers and monomers, and binding affinity toward Aß oligomers and monomers than Aß fibrils, suggesting they were selective to Aß oligomers and monomers. In addition to low toxicity, one of the fluorophores, DBAN-SLM, showed remarkably effective inhibitory effect on Aß aggregation, significant neuroprotection effect against the Aß-induced toxicities, and suppression on Aß-induced reactive oxygen species (ROS) generation. Because of excellent blood-brain barrier (BBB) permeability, good biocompatibility and stability, high specificity towards Aß oligomers as well as strong turn-on fluorescence upon Aß binding, DBAN-SLM was successfully applied for in vivo and ex vivo imaging of Aß in AD mouse model, signifying its great promise as a useful theranostic agent for the early diagnosis and therapy of AD. Our results also demonstrated for the first time that the dibutyl-2-naphthylamine moiety is a useful and effective structural building block to promote the targeting capability of oligomeric Aß.

Direct and sensitive detection of circulating miRNA in human serum by ligase-mediated amplification.

MicroRNAs (miRNA) involve in regulating different physiological processes whose dysregulation is associated with a wide range of diseases including cancers, diabetes and cardiovascular problems. Herein, we report a direct, sensitive and highly selective detection assay for circulating microRNA (miRNA). This detection strategy employs magnetic nanoparticles as the reaction platform which can not only allow online pre-concentration and selective separation but also integrates ligation reaction with amplification to enhance the sensitivity of the detection assay. With the presence of the target miRNA, the locked nucleic acid (LNA)-modified molecular beacon (MB) opens up, exposing the binding sites at two ends. The 3'- and 5'-end of the MB responsible for the attachment onto the magnetic nanoparticles, and reporting probe for the attachment of the pair of amplification probes respectively. The ligase ligate RNA to DNA enhance the amplification efficiency. Upon labelled with intercalating fluorophores (YOYO-1) on the hybrids, the quantification of the target miRNA was determined by measuring the fluorescence intensity. A detection limit of 314 fM was achieved with trace amount of sample consumption (~20 µL). As a proof of concept, miRNA-149 was chosen as the target miRNA. This assay is capable of discriminating single-base and reliably quantifying circulating miRNA-149 in both healthy and cancer patient's serums. The result obtained was comparable with that of quantitative reverse transcription polymerase chain reaction (qRT-PCR), suggesting that this direct and sensitive assay can be served as a promising, non-invasive tool for early diagnosis of breast cancer and colorectal cancer.

Total internal reflection-based single-vesicle in situ quantitative and stoichiometric analysis of tumor-derived exosomal microRNAs for diagnosis and treatment monitoring.

Purpose: Exosomes (EXs) have been increasingly recognized as natural nanoscale vehicles for microRNA (miRNA)-based cell-cell communication and an ideal source of miRNA biomarkers in bodily fluids. Current methods allow bulk analysis of the miRNA contents of EXs, but these approaches are not suitable for the in situ stoichiometry of exosomal miRNAs and fail to reveal phenotypic heterogeneity at the single-vesicle level. This study aimed to develop a single vesicle-based, mild, precise, but versatile method for the in situ quantitative and stoichiometric analysis of exosomal miRNAs. Methods: A total internal reflection fluorescence (TIRF)-based single-vesicle imaging assay was developed for direct visualization and quantification of the single-vesicles of EXs and their miRNA contents in serum microsamples. The assay uses co-delivery of inactive split DNAzymes and fluorescence-quenched substrates into nanosized EXs treated with streptolysin O to produce a target miRNA-activated catalytic cleavage reaction that amplifies the readout of fluorescence signal. We perform the in situ quantitative and stoichiometric analysis of serum exosomal hsa-miRNA-21 (miR-21), a common cancer biomarker, by using the developed TIRF imaging assay. Results: The TIRF imaging assay for serum exosomal miR-21 can distinguish cancer patients from healthy subjects with better performance than conventional real-time polymerase chain reaction (PCR) assay. The exosomal miR-21 level in serum is also informative for monitoring tumor progression and responses to treatment. Moreover, the TIRF assays can readily determine the precise stoichiometry of target exosomal miRNA contents in situ by delivering molecular beacon (MB) probes into EXs. Conclusions: The created TIRF imaging platform shows high applicability to serve as a universal and useful tool for the single-vesicle in situ quantitative and stoichiometric analysis of other disease-associated exosomal miRNAs markers and provide valuable insight into the physiological relevance of EX-mediated miRNA communication.

Highly sensitive quantification of Alzheimer's disease biomarkers by aptamer-assisted amplification.

Alzheimer's disease (AD), a chronic neurodegenerative disease associated with the loss of neurons in the brain, is the most pervasive type of dementia; 47 million people are affected, and the number is expected to increase to more than 131 million by 2050, according to Alzheimer's Disease International. Both early diagnosis and continuous monitoring are crucial for early intervention, symptomatic treatment, monitoring of the efficacy of intervention and improved patient function. Beta-amyloid peptide, tau, and phosphorylated tau are useful for screening and diagnosis; meanwhile, simultaneous assessment of multiple biomarkers is of paramount importance for accurate disease diagnosis. Methods: Herein, we report a direct, inexpensive and ultrasensitive aptamer-based multiplex assay for the quantification of trace amounts of AD biomarkers in both human serum and cerebrospinal fluid (CSF) samples. In this newly developed assay, molecular recognition of an antibody-aptamer pair provides high specificity in target detection, and the use of a DNA amplification strategy affords high sensitivity, allowing quantification of AD biomarkers in both biological fluids in 1.5 h with only a diminutive amount of the sample consumed. A tailor-made turn-on fluorophore, namely, SPOH, was employed to label the antibody-aptamer hybrids and provide a strong fluorescence signal, which was then detected with a total internal reflection fluorescence microscopy electron-multiplying charge-coupled device (TIRFM-EMCCD) imaging system. The simultaneous detection of biomarkers was achieved by a direct shape-coded method in which the nanoplatforms can be distinguished from one another by their morphologies. Results: This assay demonstrated a lower detection limit (in the femtomolar range) for AD biomarkers than the previously reported antibody-antibody method. Conclusion: The developed assay holds tremendous clinical potential for early diagnosis of AD and monitoring of its progression.

Molecular-Recognition-Based DNA Nanodevices for Enhancing the Direct Visualization and Quantification of Single Vesicles of Tumor Exosomes in Plasma Microsamples.

Tumor exosomes (Exo) are presumed to expedite both the growth and metastasis of tumors by actively participating in nearly all aspects of cancer development. Tumor-derived Exos are thus proposed as a resource for diagnostic biomarkers in bodily fluids. However, most Exo assays require large samples and are time-consuming, complicated, and costly, and thus unsuited for practical applications. Herein, we show an ultrasensitive assay that can directly visualize and quantify tumor Exos in plasma microsamples (1 µL) at the single-vesicle level. The assay uses the specific binding of activatable aptamer probes (AAP) to target Exos captured by Exo-specific antibodies on the surface of a flow cell to produce activated fluorescence. Furthermore, the bound AAP triggers in situ assembly of a DNA nanodevice with enhanced fluorescence that improves the Exo-detection sensitivity. By identifying tyrosine-protein-kinase-like 7 (PTK7), a total-internal-reflection-fluorescence (TIRF) assay for PTK7-Exo distinguishes target tumors from control subjects. This assay is also informative in monitoring tumor progression and early responses to therapy. The developed assay can be readily adapted for diagnosis and monitoring of other disease-associated Exo biomarkers.

A Zero Cross-Talk Ratiometric Two-Photon Probe for Imaging of Acid pH in Living Cells and Tissues and Early Detection of Tumor in Mouse Model.

Acid-base disorders disrupt proper cellular functions, which are associated with diverse diseases. Development of highly sensitive pH probes being capable of detecting and monitoring the minor changes of pH environment in living systems is of considerable interest to diagnose disease as well as investigate biochemical processes in vivo. We report herein two novel high-resolution ratiometric two-photon (TP) fluorescent probes, namely, PSIOH and PSIBOH derived from carbazole-oxazolidine π-conjugated system for effective sensing and monitoring acid pH in a biological system. Remarkably, PSIOH exhibited the largest emission shift of ∼169 nm from 435 to 604 nm upon pH changing from basic to acidic with an ideal p Ka value of 6.6 within a linear pH variation range of 6.2-7.0, which is highly desirable for high-resolution tracking and imaging the minor fluctuation of pH in live cells and tissues. PSIOH also exhibits high pH sensitivity, excellent photostability, and reversibility as well as low cytotoxicity. More importantly, this probe was successfully applied to (i) sense and visualize the pH alteration in HeLa cells caused by various types of exogenous stimulation and (ii) detect and differentiate cancer and tumors in liver tissues and a mouse model, realizing its practical in vitro and in vivo applications.

Silica nanoparticles induce neurodegeneration-like changes in behavior, neuropathology, and affect synapse through MAPK activation.

BACKGROUND: Silica nanoparticles (SiO2-NPs) are naturally enriched and broadly utilized in the manufacturing industry. While previous studies have demonstrated toxicity in neuronal cell lines after SiO2-NPs exposure, the role of SiO2-NPs in neurodegeneration is largely unknown. Here, we evaluated the effects of SiO2-NPs-exposure on behavior, neuropathology, and synapse in young adult mice and primary cortical neuron cultures. RESULTS: Male C57BL/6 N mice (3 months old) were exposed to either vehicle (sterile PBS) or fluorescein isothiocyanate (FITC)-tagged SiO2-NPs (NP) using intranasal instillation. Behavioral tests were performed after 1 and 2 months of exposure. We observed decreased social activity at both time points as well as anxiety and cognitive impairment after 2 months in the NP-exposed mice. NP deposition was primarily detected in the medial prefrontal cortex and the hippocampus. Neurodegeneration-like pathological changes, including reduced Nissl staining, increased tau phosphorylation, and neuroinflammation, were also present in the brains of NP-exposed mice. Furthermore, we observed NP-induced impairment in exocytosis along with decreased synapsin I and increased synaptophysin expression in the synaptosome fractions isolated from the frontal cortex as well as primary neuronal cultures. Extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) were also activated in the frontal cortex of NP-exposed mice. Moreover, inhibition of ERK activation prevented NP-mediated changes in exocytosis in cultured neurons, highlighting a key role in the changes induced by NP exposure. CONCLUSIONS: Intranasal instillation of SiO2-NPs results in mood dysfunction and cognitive impairment in young adult mice and causes neurodegeneration-like pathology and synaptic changes via ERK activation.