Visual Performance as a Function of Luminance in Glaucoma:The De Vries-Rose, Weber's, and Ferry-Porter's Law

PURPOSE. To determine whether the De Vries-Rose, Weber's, and Ferry-Porter's law, which describe visual performance as a function of luminance, also hold in patients with glaucoma. METHODS. A case-control study with 19 glaucoma patients and 45 controls, all with normal visual acuity. We measured foveal and peripheral contrast sensitivity (CS) using static perimetry and foveal and peripheral critical fusion frequency (CFF; stimulus diameter 1 degrees) as a function of luminance (0.02 to 200 cd/m(2)). ANOVA was used to analyze the effect of glaucoma and luminance on CS and CFF; analyses were adjusted for age and sex. RESULTS. Foveally, logCS was proportional to log luminance at lower luminances (de Vries-Rose) and saturated at higher luminances (Weber); glaucoma patients had a 0.4 log unit lower logCS than controls (P <0.001), independent of luminance. Peripherally, the difference was more pronounced at lower luminances (P = 0.007). CFF was linearly related to log luminance (Ferry-Porter). Glaucoma patients had a lower CFF compared with controls (P <0.001), with a smaller slope of the CFF versus log luminance curve, for both the fovea (6.8 vs. 8.7 Hz/log unit; P <0.001) and the periphery (2.5 vs. 3.4 Hz/log unit; P = 0.012). CONCLUSIONS. Even in apparently intact areas of the visual field, visual performance is worse in glaucoma patients than in healthy subjects for a wide range of luminances, without a clear luminance dependency that is consistent across the various experiments. This indicates impaired signal processing downstream in the retina and beyond, rather than an impaired light adaptation in the strictest sense

Terrace Review, May, 28, 1986

Thrombosis and Hemostasi

Characteristics and quality of oral anticoagulation treatment in pediatric patients in the Netherlands based on the CAPS cohort

Essentials: The knowledge of quality and safety of acenocoumarol and phenprocoumon use in children is limited. We used data from a multicenter retrospective follow-up study in children in the Netherlands. The quality of anticoagulation control in the first month of use was low, but improved thereafter. No thromboembolic events occurred, however bleeding events occurred in 1-3 out of 10 patients. Summary: Background: The use of vitamin-K antagonists in pediatric patients is rare and information on the quality and safety of treatment with acenocoumarol and phenprocoumon is limited. Objectives: To assess the quality, safety and effectiveness during the first year of acenocoumarol and phenprocoumon treatment in pediatric patients in the Netherlands. Methods: The Children Anticoagulation and Pharmacogenetics Study (C

The children anticoagulation and pharmacogenetics study (CAPS): Developing a dosing algorithm for acencocoumarol in paediatric patients

Background: Dosing of vitamin K antagonists (VKA) in paediatric patients is complex. The large variability in VKA dose requirement asks for elucidating the factors associated with this variability and taking these into account when defining the dose for a patient. For warfarin, paediatric dosing algorithms have been developed, but not for acenocoumarol. Objectives: To develop a dosing algorithm for acenocoumarol in pediatric patients with and without genetic information. Methods: This multicentre retrospective follow-up study was carried out in Dutch anticoagulation clinics and children's hospitals. Patients were selected when they used acenocoumarol for >1 month between January 1995 and December 2014 and were ≤18 years of age. The primary outcome was the mean daily dose during a stable period. A stable period was defined as ≥3 consecutive international normalized ratio measurements within therapeutic range over a period of ≥3 weeks. Clinical information (including height, weight and indication) and saliva samples for genotyping of CYP2C9 (∗2 and ∗3), VKORC1, CYP4F2, CYP2C18 and CYP3A4 (∗1B and ∗22) were collected. Linear regression was used to analyse their association with the log mean stable dose. Results: In total, 175 patients were included of whom 86 patients had a stable period and no missing clinical information (clinical algorithm cohort) and of 80 also genetic information was available (genetic algorithm cohort). The mean age at the stable period was 9 years. The most common indications were Fontan circulation, prosthetic heart valve, deep venous thrombosis and dilated cardiomyopathy. The clinical algorithm, containing body surface area and indication, explained 45.0% of the variability in dose requirement of acenocoumarol. By adding the genotypes of VKORC1, CYP2C18, and CYP2C9∗2/∗3, 61.8% of the variability was explained (genetic algorithm). Conclusions: Clinical factors had the largest impact on the required dose of acenocoumarol in pediatric patients. Including genetic factors in the algorithm, and especially VKORC1, increased this with 16.8%

Incidence of bleeding and thrombotic events in non-institutionalized paediatric patients using warfarin in the united kingdom

Background: Dosing of vitamin K antagonists (VKA) is complex with large inter- and intra-individual variability in patients' required VKA dose. Over- and underdosing can result in bleeding and thrombotic events. The incidence of these events in paediatric patients on warfarin therapy in a European population is unknown. Objectives: To estimate the incidence of bleeding and thrombotic events in warfarin using paediatric patients in the UK and to characterise patients who do or do not experience a bleeding or thrombotic event. Methods: Data were obtained from the UK CPRD in the period between January 1998 and November 2016. Using a cohort design, we identified all patients with ≥1 prescription for warfarin and who were ≤18 years. The date of the first prescription marked the start of the follow-up. Follow-up was classified into periods of warfarin use and non-use. Patients were followed until 19 years of age, death or departure from the practice. The incidence of non-fatal bleeding and thrombotic events was assessed using both information from CPRD and the linked Hospital Episode Statistics (HES). Fatal events were identified usings the linked mortality data from the Office for National Statistics (ONS). For calculating the incidence of thrombotic events only patients without a history of thrombosis were included. Results: In total, 685 patients were identified (median age 15 years, 45.4% female) of whom 372 could be linked to the HES and ONS databases. The incidence of bleeding and thrombotic events during warfarin use was 4.08 and 1.27/100 patient years, respectively. The incidence of bleeding events during non-use was 2.65/100 patient years (relative risk 1.58, 95% confidence interval [0.89-2.80]). Only 2 fatal events occurred, one bleeding and one thrombotic event. Patients with a bleeding event tended to have a higher percentage of INR measurements with a value above 4 (9.4 vs 3.9%) and a lower fraction below 2 (18.4 vs 39.1%) compared to patients without a bleeding event during the whole follow-up. Patients with a thrombotic event showed the opposite trend, a higher percentage of INRs below 2 (45.8 vs 29.5%) and a lower percentage of INRs above 4 (2.7 vs 5.3%). All differences were not statistically significant which maybe due to the small sample size. Conclusions: The incidence of bleeding events was higher than of thrombotic events. The trends in percentages of INRs under and above therapeutic range suggest that keeping the INR within range could decrease the occurence of these events

The Weibel-Palade Body Localized SNARE (Soluble NSF Attachment Protein Receptor) Syntaxin-3 Modulates Von Willebrand Factor Secretion From Endothelial Cells

Objective Endothelial cells store von Willebrand factor (VWF) in rod-shaped secretory organelles, called Weibel-Palade bodies (WPBs). WPB exocytosis is coordinated by a complex network of Rab GTPases, Rab-effectors and SNARE proteins. We have previously identified STXBP1 as the link between the Rab27A-Slp4-a complex on WPBs and the SNARE proteins syntaxin-2 and -3. In this study we investigate the function of syntaxin-3 in VWF secretion. Approach and Results In human umbilical vein endothelial cells (HUVECs) and in blood outgrowth endothelial cells (BOECs) from healthy controls endogenous syntaxin-3 immunolocalized to WPBs. A detailed analysis of BOECs isolated from a patient with variant microvillus inclusion disease (MVID), carrying a homozygous mutation in STX3 (STX3-/-), showed a loss of syntaxin-3 protein and absence of WPB-associated syntaxin-3 immunoreactivity. Ultrastructural analysis revealed no detectable differences in morphology or prevalence of immature or mature WPBs in control versus STX3-/- BOECs. VWF multimer analysis showed normal patterns in plasma of the MVID patient, and media from STX3-/- BOECs, together indicating WPB formation and maturation are unaffected by absence of syntaxin-3. However, a defect in basal as well as Ca2+ - and cAMP-mediated VWF secretion was found in the STX3-/- BOECs. We also show that syntaxin-3 interacts with the WPB-associated SNARE protein VAMP8. Conclusions Our data reveal syntaxin-3 as a novel WPB-associated SNARE protein that controls WPB exocytosis