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Background Ischemic stroke (IS) is one of the most frequent causes of death. Since miRNAs have been illustrated to play an important role in various processes through regulation of multiple genes, and platelet function, their utility as novel biomarkers should be determined. Purpose We aimed to analyze the circulating platelet-derived miR-19a-3p, miR-186-5p, Let-7f, platelet-extracellular vesicles (EVs), leukocyte-EVs, and endothelial-EVs levels 24-h and 7-days after IS as novel diagnostic and prognostic/predictive biomarkers in 28 acute IS and 35 control patients. Methods Blood samples of 28 patients diagnosed with acute IS with hyper platelet reactivity were collected 24-h and 7-days after stroke and 35 age- and gender-matched individuals free of stroke with multiple risk factors for cardiovascular disease. Platelet reactivity was assessed by AA-, TRAP-, ADP-induced platelet aggregometry. PlasmaRNA was extracted; quality RNA was assessed: fluorometric assay; RT-PCR for miRNAs expression measurement and flow-cytometry for EVs determination p Results Patients with IS on day-1 had significantly higher platelet reactivity assessed by AA-induced platelet aggregometry compared to controls (p=0.001). Patients with normal platelet activation had significantly higher miR-186-5p expression levels compared to patients with HPR at day-1 acute-stroke (p=0.034). Seven days after acute stroke, expression levels of miR-186-5p significantly decreased in the same patients with normal platelet reactivity (p=0.036). Patients with HPR had significantly elevated platelet-EVs (CD62) concentration compared to patients with normal platelet reactivity at the day of 1 acute-stroke (p=0.012). Similarly, patients with HPR had significantly higher leukocyte-EVs (CD45) concentration compared to patients with normal platelet function at day-1 acute-stroke (p=0.002). Diagnostic values of baseline miRNAs and EVs were evaluated with receiver operating characteristic curve analysis. ROC curve showed that pooling the miR-19a-3p expressions, platelet-EVs, and leukocyte-EVs concentration yielded a higher AUC than the value of each individual biomarker as AUC was 0.893 (95% CI, 0.79–0.99). Patients with moderate stroke had significantly elevated miR-19a-3p expression levels compared with patients with minor stroke at the day of acute IS. AUC in ROC curve analysis was 0.867, (95% CI, 0.74–0.10) p=0.001. Conclusions Our analysis showed alteration of circulating miRNAs and EVs after IS. Combination of miR-19a-3p, Let-7f, platelet-EVs and leukocyte-EVs might have a diagnostic value for acute stroke and miR-19a-3p can predict the severity of stroke in IS patients. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Science Centre - Narodowe Centrum Nauki

Background Transcatheter aortic valve implantation (TAVI) is a novel treatment for aortic stenosis (AS), associated with better outcomes than surgical aortic valve replacement in high-risk patients. However, up to 29% of patients annually experience major adverse cardiac and cerebrovascular events (MACCE) after TAVI. MACCE are mostly caused by atherothrombosis, i.e. formation of platelet aggregates (thrombi) on ruptured atherosclerotic plaques. Because platelets release extracellular vesicles (EVs) during thrombus formation, we hypothesized that EVs are a biomarker to predict MACCE after TAVI. Methods This was a multicentre, prospective clinical study. Venous blood was collected 1 day before TAVI and at hospital discharge (n=57, mean age 79.9+6.4 years, 49% male). Flow cytometry (Apogee A60-Micro) was used to determine concentrations of plasma EVs labelled with markers for endothelial cells (CD146), leukocytes (CD45), platelets and megakaryocytes (CD61) and activated platelets (CD62p). Analysis of flow cytometry data files was fully automated. Rosetta Calibration (Exometry) and Flow-SR were used for diameter and refractive index determination. Wilcoxon signed rank test was used to compare EV concentrations before and after TAVI. The predictive value of EVs for MACCE and the cut-offs were calculated using a receiver operating characteristic curve. Logistic regression model incorporating EV concentrations and clinical characteristics was used to determine the best model for MACCE prediction. Results Concentrations of EVs from activated platelets increased, whereas from leukocytes decreased after TAVI, compared to the measurement before (p=0.06, p=0.04, respectively). Among 55 patients discharged from the hospital, 14 patients experienced MACCE (25%) during the median 15 months of observation. Increased baseline concentration of leukocyte EVs and male gender were the only independent predictors of MACCE in multivariable analysis (OR 4.01, 95% CI 0.77–23.77, p=0.04 for leukocyte EVs; OR 6.84, 95% CI 1.41–33.17, p=0.03 for male gender). Conclusions We identified increased concentrations of leukocyte EVs as new candidate biomarkers to predict MACCE after TAVI. Leukocyte EVs could be used to augment risk stratification in this patient cohort. The next step is to validate the clinical applicability of EVs to predict post-TAVI MACCE in a large-scale clinical trial. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Young Investigator Grant of the Polish Society of Cardiology

Background Acute coronary syndrome (ACS), which comprises acute myocardial infarction (AMI) and unstable angina pectoris (UAP), is one of the main causes of mortality worldwide. Cardiac troponin is the gold standard to diagnose AMI. Troponin has two main disadvantages: it is negative in patients with UAP but positive in other diseases. During ACS, activated platelets release extracellular vesicles (EVs), which promote coagulation and associate with fibrin, and contribute to thrombus formation. We hypothesized that the concentration and composition of circulating platelet EVs (1) change in blood of patients with ACS compared to patients with other causes of chest pain, and (2) thereby allow earlier diagnosis of ACS than cardiac troponin. Purpose We aimed to determine the diagnostic value of circulating platelet EVs as novel early biomarkers of developing ACS. Methods We conducted a prospective, multicentre trial enrolling 105 patients who presented to the emergency department with suspected ACS. Blood was collected at admission to measure the concentration of EVs and cardiac troponin. Flow cytometry (Apogee A60-Micro) was used to determine plasma concentrations of platelet EVs exposing P-selectin (CD61+/CD62p+) and fibrin (CD61+/fibrin+). Results Plasma concentrations of platelet EVs exposing fibrin was lower in patients with ACS, compared to patients with other causes of chest pain (p=0.023) and lower in patients with an occlusive thrombus compared to non-occlusive plaque (p=0.015). Fibrin exposing-EVs were independent predictors of ACS (OR 8.2, CI 1.3–16.4) in multivariate analysis, allowing to diagnose ACS with 75% sensitivity and 72% specificity. Among patients with pain onset less than 2 hours before presentation, fibrin-exposing EVs had substantially better diagnostic performance than troponin (area under the ROC curve 0.90 vs. 0.74, respectively). Regarding other causes of chest pain, fibrin-exposing EVs were the lowest in patients with ACS, higher in patients with other cardiological causes of chest pain, and the highest in patients with non-cardiological causes of chest pain (p=0.036). Conclusions Circulating fibrin-exposing EVs are early biomarkers of developing ACS, superior to cardiac troponin in patients with pain onset less than 2 hours before presentation. Incorporation of EV measurements into the ACS diagnostic algorithm might revolutionise thrombotic risk stratification in the emergency setting. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Specialised Research Fellowship, “Club 30” of the Polish Society of Cardiology

Introduction The platelet P2Y12 antagonist ticagrelor reduces all-cause and cardiovascular mortality in patients after acute myocardial infarction (AMI) compared to clopidogrel, but the underlying mechanism is unknown. Because activated platelets release prothrombotic extracellular vesicles (EVs) exposing P-selectin, fibrinogen and phosphatidylserine (PS), we hypothesized that ticagrelor inhibits the release of EVs compared to clopidogrel. Purpose To compare the effects of ticagrelor and clopidogrel on the concentrations of platelet EVs in relation to platelet reactivity, and on the concentrations of EVs from other P2Y12-exposing cells (leukocytes, endothelial cells). Methods After the percutaneous coronary intervention, patients with first AMI (n=60, age 64.5±10.8 years, 68% male) were randomized in 1:1 ratio to antiplatelet therapy with ticagrelor or clopidogrel. Venous blood was collected from fasting patients at randomisation, 48 hours after randomisation, and 6 months following the index hospitalization with informed consent. Flow cytometry (Apogee A60 Micro) was used to determine plasma concentrations of EVs labelled with antibodies for activated platelets (CD61, CD62p; PEVs), fibrinogen, phosphatidylserine (PS), leukocytes (CD45; LEVs) and endothelial cells (CD146; EEVs). To maximize the reliability, the analysis of the 1,224 flow cytometry data files was performed with software enabling automatic flow rate stabilization, diameter and refractive index determination, size distribution fitting, fluorescent gate determination, and statistics reporting (MATLAB R2018a). To differentiate between EVs and small platelets, only particles Results Concentrations of PEVs exposing P-selectin, fibrinogen and PS were lower after 6 months of therapy with ticagrelor compared to clopidogrel, and decreased over time (p=0.034; p=0.021; p=0.018, respectively). Concentrations of LEVs were lower both after 72 hours and after 6 months of therapy with ticagrelor compared to clopidogrel (p=0.018; p Conclusions Ticagrelor decreases concentrations of prothrombotic EVs, compared to clopidogrel, suggesting that the clinical benefits of ticagrelor may be at least partly explained by inhibition of EV release from activated platelets. Further research is warranted to link this effect with clinical outcomes. Acknowledgement/Funding Medical University of Warsaw (1WR/PM2/18)

The research field of extracellular vesicles (EVs), such as microparticles and exosomes, is growing exponentially. The goal of this review is to provide an overview of recent developments relevant to the readers of the Journal of Thrombosis and Haemostasis. We will discuss nomenclature, the presence of EVs in fluids, methods of isolation and detection, and emerging clinical implications. Although research on EVs has been performed within the ISTH for over a decade, most of the recent research on EVs has been brought together by the International Society on Extracellular Vesicles (ISEV). To achieve an overview of recent developments, the information provided in this review comes not only from publications, but also from latest meetings of the ISEV (April 2015, Washington, DC, USA), the International Society on Advancement of Cytometry (June 2015, Glasgow, UK), and the ISTH (June 2015, Toronto, Canada).

Essentials Standardization of extracellular vesicle (EV) measurements by flow cytometry needs improvement. Hollow organosilica beads were prepared, characterized, and tested as reference particles. Light scattering properties of hollow beads resemble that of platelet-derived EVs. Hollow beads are ideal reference particles to standardize scatter flow cytometry research on EVs. Summary Background The concentration of extracellular vesicles (EVs) in body fluids is a promising biomarker for disease, and flow cytometry remains the clinically most applicable method to identify the cellular origin of single EVs in suspension. To compare concentration measurements of EVs between flow cytometers, solid polystyrene reference beads and EVs were distributed in the first ISTH-organized interlaboratory comparison studies. The beads were used to set size gates based on light scatter, and the concentration of EVs was measured within the size gates. However, polystyrene beads lead to false size determination of EVs, owing to the mismatch in refractive index between beads and EVs. Moreover, polystyrene beads gate different EV sizes on different flow cytometers. Objective To prepare, characterize and test hollow organosilica beads (HOBs) as reference beads to set EV size gates in flow cytometry investigations. Methods HOBs were prepared with a hard template sol-gel method, and extensively characterized for morphology, size, and colloidal stability. The applicability of HOBs as reference particles was investigated by flow cytometry with HOBs and platelet-derived EVs. Results HOBs proved to be monodisperse with a homogeneous shell thickness. Two-angle light-scattering measurements by flow cytometry confirmed that HOBs have light-scattering properties similar to those of platelet-derived EVs. Conclusions Because the structure and light-scattering properties HOBs resemble those of EVs, HOBs with a given size will gate EVs of the same size. Therefore, HOBs are ideal reference beads with which to standardize optical measurements of the EV concentration within a predefined size range.

Antacids neutralize gastric acid and are, partly due to their over-the-counter availability, broadly used in the treatment of gastroesophageal reflux disease (GERD) in adults. They are utilized for more than 2,000 years, though evidence of the effectiveness and safety is limited in infants [1]. Antacids have an effect on the short-term relief of heartburn and the healing of esophagitis. Characteristic antacids consist of alkali complexes of aluminum and/or magnesium, aluminum and magnesium phosphates, magnesium trisilicate, carbonate, and bicarbonate salts [2]. Alginate-based raft-forming formulations vary from conventional antacids by forming a gel on the surface of the gastric contents and contain sodium or potassium bicarbonate. Alginates and antacids components are frequently combined in one product. Because of potential toxicity, prolonged use of antacids should be avoided [3].

LR: 20161010; CI: Copyright (c) 2016; JID: 9317982; OTO: NOTNLM; 2016/05/13 [received]; 2016/09/06 [revised]; 2016/09/06 [accepted]; aheadofprint Extracellular vesicles (EVs) mediate normal physiological homeostasis and pathological processes by facilitating intercellular communication. Research of EVs in basic science and clinical settings requires both methodological standardization and development of reference materials (RM). Here, we show insights and results of biological RM development for EV studies. We used a three-step approach to find and develop a biological RM. First, a literature search was done to find candidates for biological RMs. Second, a questionnaire was sent to EV researchers querying the preferences for RM and their use. Third, a biological RM was selected, developed, characterized, and evaluated. The responses to the survey demonstrated a clear and recognized need for RM optimized for the calibration of EV measurements. Based on the literature, naturally occurring and produced biological RM, such as virus particles and liposomes, were proposed as RM. However, none of these candidate RMs have properties completely matching those of EVs, such as size and refractive index distribution. Therefore, we evaluated the use of nanoerythrosomes (NanoE), vesicles produced from erythrocytes, as a potential biological RM. The strength of NanoE is their resemblance to EVs. Compared to the erythrocyte-derived EVs (eryEVs), NanoE have similar morphology, a similar refractive index (1.37), larger diameter (70% of the NanoE are over 200nm), and increased positive staining for CD235a and lipids (Di-8-ANEPPS) (58% and 67% in NanoE vs. 21% and 45% in eryEVs, respectively). Altogether, our results highlight the general need to develop and validate new RM with similar physical and biochemical properties as EVs to standardize EV measurements between instruments and laboratories. Extracellular vesicles (EVs) mediate normal physiological homeostasis and pathological processes by facilitating intercellular communication. Research of EVs in basic science and clinical settings requires both methodological standardization and development of reference materials (RM). Here, we show insights and results of biological RM development for EV studies. We used a three-step approach to find and develop a biological RM. First, a literature search was done to find candidates for biological RMs. Second, a questionnaire was sent to EV researchers querying the preferences for RM and their use. Third, a biological RM was selected, developed, characterized, and evaluated. The responses to the survey demonstrated a clear and recognized need for RM optimized for the calibration of EV measurements. Based on the literature, naturally occurring and produced biological RM, such as virus particles and liposomes, were proposed as RM. However, none of these candidate RMs have properties completely matching those of EVs, such as size and refractive index distribution. Therefore, we evaluated the use of nanoerythrosomes (NanoE), vesicles produced from erythrocytes, as a potential biological RM. The strength of NanoE is their resemblance to EVs. Compared to the erythrocyte-derived EVs (eryEVs), NanoE have similar morphology, a similar refractive index (137), larger diameter (70% of the NanoE are over 200 nm), and increased positive staining for CD235a and lipids (Di-8-ANEPPS) (58% and 67% in NanoE vs. 21% and 45% in eryEVs, respectively). Altogether, our results highlight the general need to develop and validate new RM with similar physical and biochemical properties as EVs to standardize EV measurements between instruments and laboratories. (C) 2016 The Authors. Published by Elsevier B.V.

Background Enumeration of extracellular vesicles has clinical potential as a biomarker for disease. In biological samples, the smallest and largest vesicles typically differ 25-fold in size, 300,000-fold in concentration, 20,000-fold in volume, and 10,000,000-fold in scattered light. Because of this heterogeneity, the currently employed techniques detect concentrations ranging from 10(4) to 10(12) vesicles mL(-1) . Objectives To investigate whether the large variation in the detected concentration of vesicles is caused by the minimum detectable vesicle size of five widely used techniques. Methods The size and concentration of vesicles and reference beads were measured with transmission electron microscopy (TEM), a conventional flow cytometer, a flow cytometer dedicated to detecting submicrometer particles, nanoparticle tracking analysis (NTA), and resistive pulse sensing (RPS). Results Each technique gave a different size distribution and a different concentration for the same vesicle sample. Conclusion Differences between the detected vesicle concentrations are primarily caused by differences between the minimum detectable vesicle sizes. The minimum detectable vesicle sizes were 70-90 nm for NTA, 70-100 nm for RPS, 150-190 nm for dedicated flow cytometry, and 270-600 nm for conventional flow cytometry. TEM could detect the smallest vesicles present, albeit after adhesion on a surface. Dedicated flow cytometry was most accurate in determining the size of reference beads, but is expected to be less accurate on vesicles, owing to heterogeneity of the refractive index of vesicles. Nevertheless, dedicated flow cytometry is relatively fast and allows multiplex fluorescence detection, making it most applicable to clinical research.

Cell-derived or extracellular vesicles, including microparticles and exosomes, are abundantly present in body fluids such as blood. Although such vesicles have gained strong clinical and scientific interest, their detection is difficult because many vesicles are extremely small with a diameter of less than 100 nm, and, moreover, these vesicles have a low refractive index and are heterogeneous in both size and composition. In this review, we focus on the relatively high throughput detection of vesicles in suspension by flow cytometry, resistive pulse sensing, and nanoparticle tracking analysis, and we will discuss their applicability and limitations. Finally, we discuss four methods that are not commercially available: Raman microspectroscopy, micro nuclear magnetic resonance, small-angle X-ray scattering (SAXS), and anomalous SAXS. These methods are currently being explored to study vesicles and are likely to offer novel information for future developments.

Light of short wavelengths has been shown to play a key role in non-image forming responses. Due to aging, the ocular lens becomes more yellow reducing the transmission of short wavelengths in the elderly. In the present study, we make use of cataract surgery to investigate the effects of a relative increase of short wavelength transmission on melatonin- and sleep-wake rhythms (N = 14). We observed, on average, a delay of the sleep-wake and the nocturnal melatonin rhythms after cataract surgery. This delay is tentatively attributed to a relatively large increase of light transmittance in the evening hours more than an increase of the already relatively high light intensities found in the daytime. The later phase that we observed after cataract surgery (clear lens) as compared to the earlier phase observed before cataract (yellowish lens) is in agreement with the general later phase reported in the young (clear lens) population.

Benefits attributed to wound scabs include prevention of blood loss and protection against infection. However, when formation of a wound scab is prevented, the risk of infection is reduced. Moreover, in the absence of a wound scab, wounds heal faster and scar formation is reduced. The question arises why we develop a wound scab. Here we show that wound scabs inhibit transmission of ultraviolet radiation (UVR). We compared the UVR transmittance of human wound scabs to sunscreen by measuring the sun protection factor (SPF) with diffuse transmittance spectroscopy. Three wound scabs showed SPFs of 70, 84, and 300, which is more effective than the most protective commercially available sun block. Because our results demonstrate that a wound scab offers natural protection against UVR, and because no beneficial trait is attributed to wound scabs, we hypothesize that the main function of wound scabs is to limit DNA damage in underlying cells during regeneration of wound tissue exposed to sunlight, thereby reducing the risk of developing skin cancer.

Summary. Background: Microparticles and exosomes are cell-derived vesicles and potential biomarkers for disease. Recently, the Scientific Standardization Committee collaborative workshop of the ISTH initiated standardization of vesicle detection by flow cytometry with polystyrene beads. Because polystyrene beads have different optical properties from biological vesicles, and because the mechanisms causing the detection signal are incompletely understood, there are contradictions between expected and observed results. Objectives: To develop a model with which to relate the detection signal of a flow cytometer to the diameter of vesicles and clarify observed discrepancies. Methods: We combined measurements of polystyrene and silica beads with an estimated refractive index of vesicles and performed Mie calculations of light scattering. Results: We established the relationship between measured light scattering and the diameter of vesicles. The Megamix gating strategy proposed by the Scientific Standardization Committee selects single vesicles and cells with diameters between 800 and 2400 nm when applied on the forward-scattering detector of regular flow cytometers. Nevertheless, we demonstrated that, irrespective of the applied gating, multiple vesicles smaller than 220 nm or multiple 89-nm silica beads were counted as a single event signal at sufficiently high concentrations. Conclusions: Vesicle detection by flow cytometry is attributed to large single vesicles and swarm detection of smaller vesicles; that is, multiple vesicles are simultaneously illuminated by the laser beam and counted as a single event signal. Swarm detection allows the detection of smaller vesicles than previously thought possible, and explains the finding that flow cytometry underestimates the concentration of vesicles.

In the Netherlands timolol maleate, probably the drug of first choice in antiglaucoma therapy, is often combined with other intraocular pressure lowering drugs. The efficacy of most combinations have been discussed in the literature several times, except the one with aceclidine, a parasympathetic drug, that has a reasonable popularity in Western Europe. Unlike pilocarpine, aceclidine does not seem to give a clinically significant additional pressure lowering effect in timolol pre-treated eyes. The decrease in IOP in aceclidine pre-treated eyes after single dose timolol seems to be an effect of timolol alone. Our results suggest that co-administration of timolol and aceclidine is not a rational action in antiglaucomatous therapy.

We use transmission and backscattering optical coherence tomography (OCT) to distinguish and quantify dependent and multiple scattering effects in turbid media. With transmission OCT the dependent scattering coefficients for a range of monodisperse silica particle suspensions are determined. An excellent agreement is observed between the measured dependent scattering coefficients and calculations based on Mie calculations, the Percus-Yevick radial distribution function, and coherent light scattering theory. Backscattering OCT measurements are fitted using the extended Huygens-Fresnel (EHF) model with the dependent scattering coefficients obtained from the transmission OCT measurements as input parameters. Good agreement between the EHF model and the backscattering OCT measurements is observed. For large particles, the rms scattering angle θrms obtained from the EHF fit is in fair agreement with θrms calculated from the transmission OCT data.

Light is the signal that entrains the biological clock in humans to the 24-hour external time. Recently, it has been shown that short wavelengths play a key role in this process. In the present study, we describe a procedure to measure, objectively and in a quick way, the spectral composition of the light reaching the retina in vivo. The instruments involved are the foveal reflection analyzer (FRA) and the macular pigment reflectometer (MPR). By making use of these reflectometers, we show quantitatively that in subjects with cataracts, the light input is especially reduced in the short wavelength range. After cataract surgery during which the crystalline lens is replaced by a transparent artificial lens, the transmittance of the short wavelengths (between 420-500 nm) improved on average by a factor of 4. We conclude that this technique holds great promises for the chronobiological field because it allows for quantification of the spectral composition and light levels reaching the retina in vivo.

Microparticles and exosomes are cell-derived microvesicles present in body fluids that play a role in coagulation, inflammation, cellular homeostasis and survival, intercellular communication, and transport. Despite increasing scientific and clinical interest, no standard procedures are available for the isolation, detection and characterization of microparticles and exosomes, because their size is below the reach of conventional detection methods. Our objective is to give an overview of currently available and potentially applicable methods for optical and non-optical determination of the size, concentration, morphology, biochemical composition and cellular origin of microparticles and exosomes. The working principle of all methods is briefly discussed, as well as their applications and limitations based on the underlying physical parameters of the technique. For most methods, the expected size distribution for a given microvesicle population is determined. The explanations of the physical background and the outcomes of our calculations provide insights into the capabilities of each method and make a comparison possible between the discussed methods. In conclusion, several (combinations of) methods can detect clinically relevant properties of microparticles and exosomes. These methods should be further explored and validated by comparing measurement results so that accurate, reliable and fast solutions come within reach.

This paper introduces the adaptive antenna array as a possible solution to interference to received GLONASS and GPS signals. Several possible array structures and processors are compared, resulting in a preferred array of 5 elements with a power-inversion processor. Special attention is paid to the array compatibility with the GPS and GLONASS receivers' tracking processes and to the situation where no interference is received. These considerations lead to specific array design choices. Without these choices, a GPS or GLONASS receiver would not be able to function satisfactorily.

Exergy analysis is a general method for efficiency analysis of systems and processes. The use of the exergy concept and the analysis of ultimate efficiencies of processes is more or less still limited to the academic world. There are several reasons why its industrial use is still limited. To overcome some of the difficulties in industrial application of exergy analysis, it was decided to develop a supporting computer program. The program is aimed specifically at the process industry and enables both experts and relatively unexperienced people on the subject to apply the concept of exergy in a convenient and easy manner. Also the benefits of knowledge based systems were investigated. The main function of the program is to calculate the efficiencies of a process. To assist the user in judging a process, these efficiencies will also be evaluated by means of comparison with similar existing processes. We are currently working on the first steps towards a Case Based Reasoning system. As a similarity function for processes, neural networks are employed.

27 children (38 eyes) with cataracts of different origins were treated using iris fixated one-piece Iris-Claw intraocular lenses. Visual acuities outcome in this group was comparable with the results in other series. The Iris-Claw lens is a very versatile IOL, which can be used in most cataract procedures, it can be removed and exchanged with minimal surgical trauma; therefore it is an effective modality in correction of the developmental changes in the refraction of the very young and growing, aphakic eye.

Vertical fusional movements elicited by stimulation of the non-foveal retina cannot be distinguished from movements elicited by foveal stimulation, except for a difference in the ratio between the amplitude of the response and the amplitude of the stimulus. This ratio is dependent on target configuration and on the retinal area stimulated. In some circumstances, if the size and richness of contour balances against the object fixated at the fovea, bifoveal fixation can be disrupted. It can be assumed that the stimulus for the motor response is made up of foveal as well as peripheral retinal stimulation. it is plausible that there is a gradient over the retina: the influence of the stimulated retinal area decreases form the fovea towards the periphery.

The populations formed by the pupils of the eleven Dutch institutions for visually handicapped children on the first of January 1980 were investigated, repeating the investigation of the International Association for Prevention of Blindness in 1970. The total number of pupils was nearly the same in both instances (1300 in 1970 and 1334 in 1980). No significant differences were found in the distribution of diagnoses and etiologies between the two groups. The congenital cataracts, the tapeto-retinal dystrophies and the optic nerve affections are still the three diagnostic groups with the highest prevalence (together 48.6%). To gain more reliable insight into morbidity patterns one needs longitudinal investigations with central registration of patient data, especially in studying the influence of pre- and perinatal problems.

A 37-year-old man, who had an oat cell carcinoma of the left lung, lost in a few months a substantial part of both visual fields, on account of a destructive retinal process. This syndrome is known in the literature as a visual paraneoplastic syndrome, which clinically shows the very rapid development of a pseudoretinitis pigmentosa sine pigmento. For most of the patients described the visual problem was the presenting symptom. In contrast with most other described cases, our patient responded very well to systemic tumor treatment and his ocular process also came to a standstill after some delay. The nature of the relationship between the primary tumor and the photoreceptor destruction is not yet clear in detail. An auto-immune process probably forms the basis of the syndrome, but hormonal activity of the tumor could not be excluded in all cases.

Bacteria, yeasts and fungi suspended in a dextran solution were added to ampoules containing strips of filter paper which were dried without vacuum conditions. The ampoules were sealed and stored in the dark at room temperature. Viability counts were made of the original suspension immediately after drying and after storage periods of 3-48 months. Although bacterial cultures of many general did not show much resistance against dry conditions, bacteria of 13 other general had survived well or moderately after 4 years of storage. Most of the dried yeast cultures had survived after this period. Of the 16 fungal genera tested, species of 6 genera exhibited growth after 4 years. Results of this study were compared with those of two other preservation methods by which the same microorganisms were used.

The vertical vergence response generally is smaller than the presented disparity. Yet fixation disparity seems not obligatory for the vertical fusional response. Fixation disparity is modeled as a phenomenon due to interaction of a fast and a slow vergence system.

Generally, the vertical vergence response is smaller than the disparity that evokes it, even within the diplopia threshold. However, subjective and objective fixation disparity values obtained with Ogle's device agreed fairly well. The reference lines in themselves appeared to be a stimulus to align the eyes. This finding limits the value of the subjective fixation disparity method when studying the vertical fusional response. Vertical fixation disparity is dependent on time of exposure. Responses of increasing amplitude take longer to reach full amplitude from the position of rest than in the reverse direction.