Human Tears Research Articles

Exploration of human tear proteome

PurposeThe tear film is a complex structure which constitutes an interface between our eyes and the external environment. Its protein, lipid and metabolite composition is highly regulated depending on several factors. Despite its attractive characteristics, this fluid is still poorly studied. Here we present an in‐depth human tear proteome based on a mass spectrometry approach.MethodsIn this study, tears of two healthy controls (two women aged 59 and 61 years) were collected with Schirmer's papers. After trypsin digestion and off‐gel electrophoresis fractionation, two proteomic analyses were performed by mass spectrometry (using LTQ Orbitrap Velos Pro coupled to a liquid chromatography). Resulting files were searched against the UniProt‐SwissProt/TrEMBL database (version 2014_10) and a false discovery rate of 1% was selected. The protein list was analysed using Ingenuity Pathways Analysis and Cytoscape software.ResultsGlobally 2105 and 825 proteins were identified with 1 and 2 unique peptides respectively after removing keratins and immunoglobulins. Regarding the 825 proteins, the top three pathways that we highlighted were the acute phase response signalling, the remodelling of epithelial adherens junctions and the clathrin‐mediated endocytosis signalling. Moreover, we identified 203 proteins that were not found in the previous published studies. By comparing our tears with others fluids, only 26.9% were identified in vitreous humor and 45.7% in plasma, confirming that tears have a specific composition.ConclusionsThanks to this study, we are able to propose an expanded tear proteome. Both specific proteins of the tears and correlations with other fluids give them a great potential for biomarker research.This study is kindly supported by the Provisu Foundation and the SNF_MVH (PMPDP3_158370).

Oligonucleotide-Based Fluorescent Probe for Sensing of Cyclic Diadenylate Monophosphate in Bacteria and Diadenosine Polyphosphates in Human Tears

Cyclic diadenylate monophosphate (c-di-AMP) and P1,P5-diadenosine-5′ pentaphosphate (Ap5A) have been determined to play important roles in bacterial physiological processes and human metabolism, respectively. However, few, if any, methods have been developed that use fluorescent sensors to sense c-di-AMP and Ap5A in the real world. To address this challenge, this study presents a fast, convenient, selective, and sensitive assay for quantifying c-di-AMP and Ap5A fluorescence based on the competitive binding of diadenosine nucleotides and a polyadenosine probe to coralyne. The designed probe consists of a 20-mer adenosine base (A20), a fluorophore unit at the 5′-end, and a quencher unit at the 3′-end. Through A2–coralyne–A2 coordination, coralyne causes a change in the conformation of A20 from that of a random coil to a folded structure, thus enabling the fluorophore to be close to the quencher. As a result, fluorescence quenching occurs between the two organic dyes. When the A20·coralyne probe encounters t...

Shoulder arthritis secondary to rotator cuff tear: A reproducible murine model and histopathologic scoring system.

Untreated rotator cuff tears can progress to a distinct form of shoulder arthritis, and the mechanism of this progression is poorly understood. Biomechanical, molecular and genetic factors may be at play, and a reliable animal model is needed to enable further research. The purpose of this study was to create a reproducible model of posttraumatic shoulder arthritis in the mouse, and to develop a scoring system for this model to enable future research on interventions, the role of various gene products, and the development of therapies to alter the natural course of the disease. Forty-five mice underwent operative ligation of the rotator cuff tendons and were followed for 45 weeks following surgery, with free cage activity post-operatively. Mice were sacrificed at various intervals from 2 to 45 weeks post-injury and histopathologic scoring was developed and tested by blinded reviewers using both quantitative computational analysis of coronal sections of the shoulder joint and semi-quantitative grading. The scoring system revealed a progressive, time-dependent set of tissue changes in the shoulder joint with features similar to human cuff tear arthropathy including acetabularization of the acromion and femoralization of the humeral head. This model establishes that osteoarthritis of the shoulder is distinct from osteoarthritis of the knee or hip, with different stages of degeneration and unique histopathologic features. Using the novel grading procedure and quantitative assessments presented here, future research using this model will enable investigators to test established and novel therapies and evaluate the role of inflammatory factors and gene products in shoulder arthritis. This study provides a reproducible mouse model of shoulder arthritis following isolated injury to the rotator cuff which elucidates characteristics of cuff tear arthropathy and provides a scoring system and venue for future research. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:506-514, 2017.

Effect of Ambient Temperature on the Human Tear Film.

During everyday life, the tear film is exposed to a wide range of ambient temperatures. This study aims to investigate the effect of ambient temperature on tear film physiology. A controlled environment chamber was used to create different ambient temperatures (5, 10, 15, 20, and 25°C) at a constant relative humidity of 40%. Subjects attended for two separate visits and were exposed to 25, 20, and 15°C at one visit and to 10 and 5°C at the other visit. The subjects were exposed to each room temperature for 10 min before investigating tear film parameters. The order of the visits was random. Tear physiology parameters assessed were tear evaporation rate, noninvasive tear break-up time (NITBUT), lipid layer thickness (LLT), and ocular surface temperature (OST). Each parameter was assessed under each condition. A threefold increase in tear evaporation rate was observed as ambient temperature increased to 25°C (P=0.00). The mean evaporation rate increased from 0.056 μL/min at 5°C to 0.17 μL/min at 25°C. The mean NITBUT increased from 7.31 sec at 5°C to 12.35 sec at 25°C (P=0.01). A significant change in LLT was also observed (P=0.00), LLT median ranged between 20 and 40 nm at 5 and 10°C and increased to 40 and 90 nm at 15, 20, and 25°C. Mean reduction of 4°C OST was observed as ambient temperature decreased from 25 to 5°C. Ambient temperature has a considerable effect on human tear film characteristics. Tear evaporation rate, tear LLT, tear stability, and OST were considerably affected by ambient temperature. Chronic exposure to low ambient temperature would likely result in symptoms of dry eye and ultimately ocular surface disorders.

Human tear-production rate from closed-eye Schirmer-strip capillary dynamics

A Schirmer tear test (STT) is commonly used to gauge human tear production, especially when dry-eye symptoms present. In an STT, the rounded tip of a standardized paper strip is inserted into the lower fornix of the eye, and the wetted length extending out from the lower lid is recorded after 5min of eye closure. Longer wetted lengths suggest higher tear production rates. To date, however, there is no methodology to transform STT transient wetting lengths into basal tear- production rates. We develop a physical model to elucidate wetting kinetics in a Schirmer strip. Tear evaporation from the exposed portion of the strip and gravity are accounted for. Careful consideration of the initial depletion of tear in the closed-eye tear prism reveals an initial fast increase in wetted length followed by slower growth. Excellent agreement of the proposed model is achieved with experimental observation. When evaporation is negligible, the slow-growth regime exhibits a linear increase of wetted length in time. The linear-length-growth time regime permits simple calculation of quantitative tear-production rates. We suggest measuring several dynamic wetting lengths along a sheathed Schirmer strip and near the 5-min insertion duration followed by fitting to a straight line. The slope of the length-versus-time data gives the basal lacrimal-supply rate.

Gene expression in human meniscal tears has limited association with early degenerative changes in knee articular cartilage

ABSTRACTPurpose/Aim: Meniscus tears are a common injury to the knee associated with the development of osteoarthritis. Gene expression in the injured meniscus may be associated with early degeneration in the articular cartilage. The purpose of this study was to test the hypothesis that gene expression in meniscus tears is associated with early degenerative changes in the articular cartilage at the time of partial meniscectomy. Materials and Methods: Torn meniscus was removed at the time of partial meniscectomy in 68 patients without radiographic osteoarthritis. Meniscal mRNA expression was measured by quantitative PCR for multiple molecular markers of osteoarthritis and cartilage homeostasis. The presence of early degenerative changes in the knee was recorded by X-ray (N = 63), magnetic resonance imaging (MRI, N = 48), and arthroscopy (N = 63). Gene expression was tested for correlation with the presence/absence of degenerative changes after adjusting for age, sex, and body mass index. Results: Overall gene expression varied significantly with degenerative changes based on X-ray (P = 0.047) and MRI (P = 0.018). The linear combination of gene variation was also significant. However, only adiponectin (ADIPOQ) (P = 0.015) was expressed at a significantly lower level in patients with chondrosis on MRI, while the expression of ADIPOQ (P = 0.035) and resistin (RETN) (P = 0.017) was higher in patients with early degenerative changes on X-ray. None of the genes varied significantly with presence/absence of chondrosis as measured by arthroscopy. Conclusions: There is an overall association of gene expression in meniscal tears to early degenerative changes in the knee, but only a limited number of specific genes demonstrate this relationship. The roles of adiponectin and resistin in knee injury and osteoarthritis deserve further study.

Evaporation and Hydrocarbon Chain Conformation of Surface Lipid Films

PurposeThe inhibition of the rate of evaporation (Revap) by surface lipids is relevant to reservoirs and dry eye. Our aim was to test the idea that lipid surface films inhibit Revap. MethodsRevap were determined gravimetrically. Hydrocarbon chain conformation and structure were measured using a Raman microscope. Six 1-hydroxyl hydrocarbons (11-24 carbons in length) and human meibum were studied. Reflex tears were obtained from a 62-year-old male. ResultsThe Raman scattering intensity of the lipid film deviated by about 7 % for hydroxyl lipids and varied by 21 % for meibum films across the entire film at a resolution of 5 μm2. All of the surface lipids were ordered. Revap of the shorter chain hydroxyl lipids were slightly (7%) but significantly lower compared with the longer chain hydroxyl lipids. Revap of both groups was essentially similar to that of buffer. A hydroxyl lipid film did not influence Revap over an estimated average thickness range of 0.69 to >6.9 μm. Revap of human tears and buffer with and without human meibum (34.4 μm thick) was not significantly different. Revap of human tears was not significantly different from buffer. ConclusionsHuman meibum and hydroxyl lipids, regardless of their fluidity, chain length, or thickness did not inhibit Revap of buffer or tears even though they completely covered the surface. It is unlikely that hydroxyl lipids can be used to inhibit Revap of reservoirs. Our data do not support the widely accepted (yet unconfirmed) idea that the tear film lipid layer inhibits Revap of tears.

Protein-directed synthesis of highly monodispersed, spherical gold nanoparticles and their applications in multidimensional sensing

An in-situ reduction method has been reported to prepare gold nanoparticles (GNPs) of 40–110 nm by using the green reducing agents of proteins, which are activated by H2O2 and the superoxide anion (). The protein of collagen turns HAuCl4 to the aqueous Au(I) ainions, which are further reduced by other proteins to be highly monodispersed and spherical GNPs of different sizes. The GNPs reduced by different proteins are found to be with the exposed {100} facets, the distinctive UV-vis absorption spectra and various colors (See Fig. 1). By means of extracting the color responses, such as red, green and blue (RGB) alterations, an in-situ reduction method-based multidimensional sensing platform is fabricated in the process of GNPs synthesis. Without further modification of GNPs, nine common proteins are found to be well detected and discriminated at different concentrations. Moreover, this sensing platform also demonstrates great potentials in qualitative and semiquantitative analysis on the individuals of these proteins with high sensitivity. Furthermore, the validation of this multidimensional sensing platform has been carried out by analysis on the spiked proteins in human urine and the target proteins in complex matrix (e.g. lysozyme in human tear).

Simulation of the hydrodynamic conditions of the eye to better reproduce the drug release from hydrogel contact lenses: experiments and modeling.

Currently, most in vitro drug release studies for ophthalmic applications are carried out in static sink conditions. Although this procedure is simple and useful to make comparative studies, it does not describe adequately the drug release kinetics in the eye, considering the small tear volume and flow rates found in vivo. In this work, a microfluidic cell was designed and used to mimic the continuous, volumetric flow rate of tear fluid and its low volume. The suitable operation of the cell, in terms of uniformity and symmetry of flux, was proved using a numerical model based in the Navier-Stokes and continuity equations. The release profile of a model system (a hydroxyethyl methacrylate-based hydrogel (HEMA/PVP) for soft contact lenses (SCLs) loaded with diclofenac) obtained with the microfluidic cell was compared with that obtained in static conditions, showing that the kinetics of release in dynamic conditions is slower. The application of the numerical model demonstrated that the designed cell can be used to simulate the drug release in the whole range of the human eye tear film volume and allowed to estimate the drug concentration in the volume of liquid in direct contact with the hydrogel. The knowledge of this concentration, which is significantly different from that measured in the experimental tests during the first hours of release, is critical to predict the toxicity of the drug release system and its in vivo efficacy. In conclusion, the use of the microfluidic cell in conjunction with the numerical model shall be a valuable tool to design and optimize new therapeutic drug-loaded SCLs.

Synergistic Effect of Artificial Tears Containing Epigallocatechin Gallate and Hyaluronic Acid for the Treatment of Rabbits with Dry Eye Syndrome.

Dry eye syndrome (DES) is a common eye disease. Artificial tears (AT) are used to treat DES, but they are not effective. In this study, we assessed the anti-inflammatory effect of AT containing epigallocatechin gallate (EGCG) and hyaluronic acid (HA) on DES. Human corneal epithelial cells (HCECs) were used in the WST-8 assay to determine the safe dose of EGCG. Lipopolysaccharide-stimulated HCECs showing inflammation were treated with EGCG/HA. The expression of IL-1ß, IL-6, IL-8, and TNF-α was assessed by real-time PCR and AT physical properties such as the viscosity, osmolarity, and pH were examined. AT containing EGCG and HA were topically administered in a rabbit DES model established by treatment with 0.1% benzalkonium chloride (BAC). Tear secretion was assessed and fluorescein, H&E, and TUNEL staining were performed. Inflammatory cytokine levels in the corneas were also examined. The non-toxic optimal concentration of EGCG used for the treatment of HCECs in vitro was 10 μg/mL. The expression of several inflammatory genes, including IL-1ß, IL-6, IL-8, and TNF-α, was significantly inhibited in inflamed HCECs treated with 10 μg/mL EGCG and 0.1% (w/v) HA (E10/HA) compared to that in inflamed HCECs treated with either EGCG or HA alone. AT containing E10/HA mimic human tears, with similar osmolarity and viscosity and a neutral pH. Fluorescence examination of the ocular surface of mouse eyes showed that HA increased drug retention on the ocular surface. Topical treatment of DES rabbits with AT plus E10/HA increased tear secretion, reduced corneal epithelial damage, and maintained the epithelial layers and stromal structure. Moreover, the corneas of the E10/HA-treated rabbits showed fewer apoptotic cells, lower inflammation, and decreased IL-6, IL-8, and TNF-α levels. In conclusion, we showed that AT plus E10/HA had anti-inflammatory and mucoadhesive properties when used as topical eye drops and were effective for treating DES in rabbits.

Water soluble drug releasing soft contact lens in response to pH of tears

Human tear characteristics including pH and compositions can vary significantly depending on physical and environmental factors. Contact lenses directly contact with human tears can be swelled or de-swelled depending on the pH of the solution due to the nature of the hydrogel. For examples, anionic hydrogels, when the solution's pH is low, is shrunken due to the electric attraction force within the hydrogel network; the opposite phenomenon appears when the solution is basic. The purpose of this study was to evaluate the extent of water soluble drug, hydroxyl propyl methyl cellulose, released from contact lens according to the pH of the artificial tears. Artificial tears are prepared by mixing lysozyme, albumin, sodium chloride, potassium chloride, and calcium chloride following physiological concentrations. Hydrogel contact lens was thermally polymerized using HEMA, EGDMA, and AIBN. The prepared hydrogel lens was immersed in drug for 3 hours and the eluted drug mass was measured as a function of the time. As a result, the drug was released from the lens for 12 hours in all the pH of artificial tears. At the lower pH of artificial tears (pH 5.8), the total amount of dye emitted from the lens was increased than the total amount of dye emitted at the basic tear (pH 8.4). Also, initial burst at acidic tears was increased within 1 hour. Release pattern of water-soluble drug from hydrogel lens turned out to be different depending on the pH of the artificial tears. When designing drug releasing contact lens, physiological pH of tears should be considered.

ω-3 Tear Film Lipids Correlate With Clinical Measures of Dry Eye.

Purposeω-3 and ω-6 polyunsaturated fatty acids modulate inflammatory processes throughout the body through distinct classes of lipid mediators that possess both proinflammatory and proresolving properties. The purpose of this cross-sectional study was to explore the relationship between lipid profiles in human tears and dry eye (DE) symptoms and signs.MethodsForty-one patients with normal eyelid and corneal anatomy were prospectively recruited from a Veterans Administration Hospital over 18 months. Symptoms and signs of DE were assessed, and tear samples was analyzed by mass spectrometry–based lipidomics. Statistical analyses comparing the relationship between tear film lipids and DE included Pearson/Spearman correlations and t-tests.ResultsArachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) were present in more than 90% of tear film samples. The ratio of ω-6 (AA) to ω-3 (DHA+EPA) fatty acids was correlated with multiple measures of tear film dysfunction (tear breakup time, Schirmer 2 scores, and corneal staining; all P < 0.05). Arachidonic acid–derived prostaglandin E2 was detected in the majority of samples and correlated with low tear osmolarity, meibomian gland plugging, and corneal staining.ConclusionsBoth ω-3 and ω-6 lipid circuits are activated in the human tear film. The ratio of ω-6:ω-3 tear lipids is elevated in DE patients in proportion to the degree of tear film dysfunction and corneal staining. Metabolic deficiency of ω-3 tear film lipids may be a driver of chronic ocular surface inflammation in DE.

Gene expression profiles of changes underlying different-sized human rotator cuff tendon tears

Progressive cellular and extracellular matrix (ECM) changes related to age and disease severity have been demonstrated in rotator cuff tendon tears. Larger rotator cuff tears demonstrate structural abnormalities that potentially adversely influence healing potential. This study aimed to gain greater insight into the relationship of pathologic changes to tear size by analyzing gene expression profiles from normal rotator cuff tendons, small rotator cuff tears, and large rotator cuff tears. We analyzed gene expression profiles of 28 human rotator cuff tendons using microarrays representing the entire genome; 11 large and 5 small torn rotator cuff tendon specimens were obtained intraoperatively from tear edges, which we compared with 12 age-matched normal controls. We performed real-time polymerase chain reaction and immunohistochemistry for validation. Torn rotator cuff tendons demonstrated upregulation of a number of key genes, such as matrix metalloproteinase 3, 10, 12, 13, 15, 21, and 25; a disintegrin and metalloproteinase (ADAM) 12, 15, and 22; and aggrecan. Amyloid was downregulated in all tears. Small tears displayed upregulation of bone morphogenetic protein 5. Chemokines and cytokines that may play a role in chemotaxis were altered; interleukins 3, 10, 13, and 15 were upregulated in tears, whereas interleukins 1, 8, 11, 18, and 27 were downregulated. The gene expression profiles of normal controls and small and large rotator cuff tear groups differ significantly. Extracellular matrix remodeling genes were found to contribute to rotator cuff tear pathogenesis. Rotator cuff tears displayed upregulation of a number of matrix metalloproteinase (3, 10, 12, 13, 15, 21, and 25), a disintegrin and metalloproteinase (ADAM 12, 15, and 22) genes, and downregulation of some interleukins (1, 8, and 27), which play important roles in chemotaxis. These gene products may potentially have a role as biomarkers of failure of healing or therapeutic targets to improve tendon healing.

Muscle architectural changes after massive human rotator cuff tear.

Rotator cuff (RC) tendon tears lead to negative structural and functional changes in the associated musculature. The structural features of muscle that predict function are termed "muscle architecture." Although the architectural features of "normal" rotator cuff muscles are known, they are poorly understood in the context of cuff pathology. The purpose of this study was to investigate the effects of tear and repair on RC muscle architecture. To this end thirty cadaveric shoulders were grouped into one of four categories based on tear magnitude: Intact, Full-thickness tear (FTT), Massive tear (MT), or Intervention if sutures or hardware were present, and key parameters of muscle architecture were measured. We found that muscle mass and fiber length decreased proportionally with tear size, with significant differences between all groups. Conversely, sarcomere number was reduced in both FTT and MT with no significant difference between these two groups, in large part because sarcomere length was significantly reduced in MT but not FTT. The loss of muscle mass in FTT is due, in part, to subtraction of serial sarcomeres, which may help preserve sarcomere length. This indicates that function in FTT may be impaired, but there is some remaining mechanical loading to maintain "normal" sarcomere length-tension relationships. However, the changes resulting from MT suggest more severe limitations in force-generating capacity because sarcomere length-tension relationships are no longer normal. The architectural deficits observed in MT muscles may indicate deeper deficiencies in muscle adaptability to length change, which could negatively impact RC function despite successful anatomical repair. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2089-2095, 2016.

Free amino acids: an innovative treatment for ocular surface disease

Amino acids are the basic constituents of living organisms, and have both a structural and an active dynamic role in tissue and cell physiology. Human tears contain 23 amino acids, the relative proportion of which may change with the different physiological states of the eye surface. In this review, we present a collection of data from the published literature that indicate an active role of amino acids in the maintenance of eye surface homeostasis. Moreover, another series of published clinical data indicate that supplementation of amino acids, either as food supplements or as a topical treatment in enriched eye drops, is beneficial to the eye surface, and may improve its healing in cases of eye surface disease due to different causes.

Transparent and Capacitive Bioanode Based on Specifically Engineered Glucose Oxidase

AbstractHere we detail an optimized transparent capacitive glucose oxidizing bioanode, capable of supplying current densities of 10 µA cm−2 at applied potentials of 0.1 V–0.2 V versus saturated calomel electrode, when continuously performing in a simple phosphate buffer, pH 7.4 and artificial human tears, both with a glucose concentration of 0.05 mM only. When operating in pulse mode, the bioanode was able to deliver current densities as high as 21 µA cm−2 at the beginning of the pulse with 571 µC cm−2 total charges stored. The biogenic part of the enzymatic device was a recombinant glucose oxidase mutant from Penicillium amagasakiense with high catalytic efficiency towards glucose, up to 14.5⋅104 M−1 s−1. The non‐biogenic part of the anodic system was based on a poly(3,4‐ethylenedioxythiophene)‐graphene nanocomposite, as a highly capacitive component with a capacitance density in the 1 mF cm−2 range, multi‐walled carbon nanotubes, as an additional nanostructuring element, and a conductive organic complex, as an electron shuttle between the redox enzyme and the electrode surface. The bioanode could potentially serve as a prototype of a double‐function enzymatic anode for hybrid electric power biodevices, energizing smart contact lenses.

Exosomes in tears of healthy individuals: Isolation, identification, and characterization

Exosomes represent a sort of extracellular vesicles, which transfer molecular signals in the body and contain markers of the exosome-producing cell. This study was aimed at search of exosomes in the tears of healthy humans, validation of their nature and examination of their morphological and molecular-biological characteristics. Samples of the tears individually collected from 24 healthy donors (aged 45–60 years) were centrifuged at 20000 g for 15 min to pellet cell debris. The supernatants were examined in an electron microscope using negative staining and were also used for isolation and purification of exosomes by filtration (100 nm pore-size) and double ultracentrifugation (90 min at 100000 g, 4°C). Resultant pellets were investigated by electron microscopy and immunolabeling, RNA and DNA were isolated and their sizes were determined by capillary electrophoresis, concentration and localization of nucleic acids in the isolated exosomes were studied. DNA sequencing was performed using MiSeq (Illumina, USA), data were analyzed using CLC GW 7.5 (Qiagen, USA). Sequences were mapped on human genome (hg19). Supernatants of the tears contained cell debris, spherical microparticles (20–40 nm), and vesicles; some of the vesicles had morphology and sizes corresponding to exosomes. The pellets obtained after ultracentrifugation of tears contained microparticles (17%), spherical and cup-shaped vesicles (40–100 nm, 83%), which were positive for CD63, CD9, and CD24 receptors (specific markers of exosomes). The study revealed high concentrations of exosomes in human tears; these exosomes contained both RNA (of less than 200 nucleotides in size) and DNA (of 3–9 kb in size). DNA sequencing demonstrated that about 92% of the reads was mapped to human genome.

Detection of neopterin in tear samples

Abstract The main goal of the present study was to detect neopterin concentrations in human tear samples and to evaluate its potential correlation with serum neopterin levels. For this purpose, 20 systemically healthy volunteers were recruited, and both tear and serum samples were synchronically collected from each individual. Enzyme-linked immunoassay (ELISA) was carried out to detect the quantity of neopterin in the samples. Mean human tear neopterin levels were observed as 3±0.56 nM while mean serum neopterin was 9±1.25 nM. Additionally, a significant positive correlation between tear neopterin and serum neopterin concentrations was observed. This is the first report to show neopterin concentration in human tears as a biological sample. Collecting tears from the individuals is a non-invasive sampling method, and as an analytical aspect detection of neopterin by ELISA in tear samples construct a valuable, practical and cheap procedure for the diagnosis and monitoring of intraocular inflammation and systemic immune-mediated diseases.

Chemosignalling effects of human tears revisited: Does exposure to female tears decrease males’ perception of female sexual attractiveness?

ABSTRACTGelstein et al. reported the results of three experiments suggesting a dampening influence of inhalation of female emotional tears on males’ arousal and perception of female sexual attractiveness, specifically in non-sexual situations. This prompted the hypothesis that crying exerts its influence on others not only via the auditory and visual mode but also via chemosignals. In three studies, we attempted to replicate and extend Gelstein et al.’s findings by including an additional condition with irritant tears, by using pictures of sexually attractive women, and by testing related hypotheses on the pro-social effects of exposure to tears. All three studies, separately or combined in a meta-analysis, failed to replicate the original inhibitory effects of tears. In addition, sniffing tears did not affect measures of connectedness, aggression and pro-social behaviour. It is concluded that the effects of female tears on male arousal and perception of female sexual attractiveness, if any, are very weak at best. Rather, it seems that crying exerts its strong inter-personal effects through the visual and auditory sensory channels.

Instability and Breakup of Model Tear Films.

An experimental platform to replicate the human tear film on a contact lens is presented. The influence of interfacial viscoelasticity in stabilizing in vitro model tear films against breakup and dewetting is investigated using this instrument. Model tear films consisting of bovine meibomian lipids (meibum) spread on either PBS or artificial tear solution (ATS) are created. The interfacial shear rheology of these films is measured as a function of temperature. The dewetting dynamics of these films is then investigated using the Interfacial Dewetting and Drainage Optical Platform (i-DDrOP) on top of silicone hydrogel (SiHy) contact lenses at 23 and 35°C. The film breakup times are evaluated using two parameters: onset of film breakup, Tonset for thick films (∼100 μm), and tear breakup times, TBU for thin films (∼1 μm). Thin film thinning rates as a result of evaporation are also calculated. The ATS/meibum films have the largest surface rheology and correspondingly show the largest Tonset times at both 23 and 35°C. The parameter TBU is also significantly larger for ATS/meibum (TBU ∼ 40 seconds) compared with that of ATS and PBS/meibum films (TBU ∼ 30 seconds) at room temperature. However, at 35°C, all three model tear films exhibit similar TBU ∼ 17 seconds and average rate of thinning of -4 μm/minute. Tear film stability is influenced by both surface rheology and evaporation. The in vitro tear breakup times and thinning rates of model tear films at 35°C are in good agreement with in vivo measurements previously reported, highlighting the utility of the i-DDrOP for in vitro tear film breakup research.