Why do firms go public? evidence from the banking industry

The lack of data on private firms has made it difficult to empirically examine theories of why firms go public. However, both public and private banks must disclose financial information to regulators. We exploit this requirement to explore the going-public decision. Our results indicate that banks that convert to public ownership are more likely to become targets than control banks that remain private. Banks that go public are also more likely to become acquirers than control banks. IPO banks grow faster than control banks after going public, although there is some evidence that their performance deteriorates.Financial institutions

Lutein, Zeaxanthin, and meso

Lutein, zeaxanthin, and meso-zeaxanthin are xanthophyll carotenoids found within the retina and throughout the visual system. The retina is one of the most metabolically active tissues in the body. The highest concentration of xanthophylls is found within the retina, and this selective presence has generated many theories regarding their role in supporting retinal function. Subsequently, the effect of xanthophylls in the prevention and treatment of various eye diseases has been examined through epidemiological studies, animal studies, and clinical trials. This paper attempts to review the epidemiological studies and clinical trials investigating the effects of xanthophylls on the incidence and progression of various eye diseases. Observational studies have reported that increased dietary intake and higher serum levels of lutein and zeaxanthin are associated with lower risk of age-related macular degeneration (AMD), especially late AMD. Randomized, placebo-controlled clinical trials have demonstrated that xanthophyll supplementation increases macular pigment levels, improves visual function, and decreases the risk of progression to late AMD, especially neovascular AMD. Current publications on the preventive and therapeutic effects of lutein and zeaxanthin on cataracts, diabetic retinopathy, and retinopathy of prematurity have reported encouraging results

H. Gregg Lewis Memorial Comments

Economic

Effects of Intraframe Distortion on Measures of Cone Mosaic Geometry from Adaptive Optics Scanning Light Ophthalmoscopy

Purpose: To characterize the effects of intraframe distortion due to involuntary eye motion on measures of cone mosaic geometry derived from adaptive optics scanning light ophthalmoscope (AOSLO) images. Methods: We acquired AOSLO image sequences from 20 subjects at 1.0, 2.0, and 5.08 temporal from fixation. An expert grader manually selected 10 minimally distorted reference frames from each 150-frame sequence for subsequent registration. Cone mosaic geometry was measured in all registered images (n ¼ 600) using multiple metrics, and the repeatability of these metrics was used to assess the impact of the distortions from each reference frame. In nine additional subjects, we compared AOSLO-derived measurements to those from adaptive optics (AO)-fundus images, which do not contain system-imposed intraframe distortions. Results: We observed substantial variation across subjects in the repeatability of density (1.2%–8.7%), inter-cell distance (0.8%–4.6%), percentage of six-sided Voronoi cells (0.8%–10.6%), and Voronoi cell area regularity (VCAR) (1.2%–13.2%). The average of all metrics extracted from AOSLO images (with the exception of VCAR) was not significantly different than those derived from AO-fundus images, though there was variability between individual images. Conclusions: Our data demonstrate that the intraframe distortion found in AOSLO images can affect the accuracy and repeatability of cone mosaic metrics. It may be possible to use multiple images from the same retinal area to approximate a ‘‘distortionless’’ image, though more work is needed to evaluate the feasibility of this approach. Translational Relevance: Even in subjects with good fixation, images from AOSLOs contain intraframe distortions due to eye motion during scanning. The existence of these artifacts emphasizes the need for caution when interpreting results derived from scanning instruments

Comparison of Adaptive Optics Scanning Light Ophthalmoscopic Fluorescein Angiography and Offset Pinhole Imaging

Recent advances to the adaptive optics scanning light ophthalmoscope (AOSLO) have enabled finer in vivo assessment of the human retinal microvasculature. AOSLO confocal reflectance imaging has been coupled with oral fluorescein angiography (FA), enabling simultaneous acquisition of structural and perfusion images. AOSLO offset pinhole (OP) imaging combined with motion contrast post-processing techniques, are able to create a similar set of structural and perfusion images without the use of exogenous contrast agent. In this study, we evaluate the similarities and differences of the structural and perfusion images obtained by either method, in healthy control subjects and in patients with retinal vasculopathy including hypertensive retinopathy, diabetic retinopathy, and retinal vein occlusion. Our results show that AOSLO OP motion contrast provides perfusion maps comparable to those obtained with AOSLO FA, while AOSLO OP reflectance images provide additional information such as vessel wall fine structure not as readily visible in AOSLO confocal reflectance images. AOSLO OP offers a non-invasive alternative to AOSLO FA without the need for any exogenous contrast agent

\u3cem\u3eIn vivo\u3c/em\u3e Imaging of Human Retinal Microvasculature Using Adaptive Optics Scanning Light Ophthalmoscope Fluorescein Angiography

The adaptive optics scanning light ophthalmoscope (AOSLO) allows visualization of microscopic structures of the human retina in vivo. In this work, we demonstrate its application in combination with oral and intravenous (IV) fluorescein angiography (FA) to the in vivo visualization of the human retinal microvasculature. Ten healthy subjects ages 20 to 38 years were imaged using oral (7 and/or 20 mg/kg) and/or IV (500 mg) fluorescein. In agreement with current literature, there were no adverse effects among the patients receiving oral fluorescein while one patient receiving IV fluorescein experienced some nausea and heaving. We determined that all retinal capillary beds can be imaged using clinically accepted fluorescein dosages and safe light levels according to the ANSI Z136.1-2000 maximum permissible exposure. As expected, the 20 mg/kg oral dose showed higher image intensity for a longer period of time than did the 7 mg/kg oral and the 500 mg IV doses. The increased resolution of AOSLO FA, compared to conventional FA, offers great opportunity for studying physiological and pathological vascular processes

Longitudinal imaging of microvascular remodelling in proliferative diabetic retinopathy using adaptive optics scanning light ophthalmoscopy

Purpose To characterise longitudinal changes in the retinal microvasculature of type 2 diabetes mellitus (T2DM) as exemplified in a patient with proliferative diabetic retinopathy (PDR) using an adaptive optics scanning light ophthalmoscope (AOSLO). Methods A 35-year-old T2DM patient with PDR treated with scatter pan-retinal photocoagulation at the inferior retina 1 day prior to initial AOSLO imaging along with a 24-year-old healthy control were imaged in this study. AOSLO vascular structural and perfusion maps were acquired at four visits over a 20-week period. Capillary diameter and microaneurysm area changes were measured on the AOSLO structural maps. Imaging repeatability was established using longitudinal imaging of microvasculature in the healthy control. Results Capillary occlusion and recanalisation, capillary dilatation, resolution of local retinal haemorrhage, capillary hairpin formation, capillary bend formation, microaneurysm formation, progression and regression were documented over time in a region 2° superior to the fovea in the PDR patient. An identical microvascular network with same capillary diameter was observed in the control subject over time. Conclusions High-resolution serial AOSLO imaging enables in vivo observation of vasculopathic changes seen in diabetes mellitus. The implications of this methodology are significant, providing the opportunity for studying the dynamics of the pathological process, as well as the possibility of identifying highly sensitive and non-invasive biomarkers of end organ damage and response to treatment

Classification of Human Retinal Microaneurysms Using Adaptive Optics Scanning Light Ophthalmoscope Fluorescein Angiography

Purpose. Microaneurysms (MAs) are considered a hallmark of retinal vascular disease, yet what little is known about them is mostly based upon histology, not clinical observation. Here, we use the recently developed adaptive optics scanning light ophthalmoscope (AOSLO) fluorescein angiography (FA) to image human MAs in vivo and to expand on previously described MA morphologic classification schemes. Methods. Patients with vascular retinopathies (diabetic, hypertensive, and branch and central retinal vein occlusion) were imaged with reflectance AOSLO and AOSLO FA. Ninety-three MAs, from 14 eyes, were imaged and classified according to appearance into six morphologic groups: focal bulge, saccular, fusiform, mixed, pedunculated, and irregular. The MA perimeter, area, and feret maximum and minimum were correlated to morphology and retinal pathology. Select MAs were imaged longitudinally in two eyes. Results. Adaptive optics scanning light ophthalmoscope fluorescein angiography imaging revealed microscopic features of MAs not appreciated on conventional images. Saccular MAs were most prevalent (47%). No association was found between the type of retinal pathology and MA morphology (P = 0.44). Pedunculated and irregular MAs were among the largest MAs with average areas of 4188 and 4116 μm2, respectively. Focal hypofluorescent regions were noted in 30% of MAs and were more likely to be associated with larger MAs (3086 vs. 1448 μm2, P = 0.0001). Conclusions. Retinal MAs can be classified in vivo into six different morphologic types, according to the geometry of their two-dimensional (2D) en face view. Adaptive optics scanning light ophthalmoscope fluorescein angiography imaging of MAs offers the possibility of studying microvascular change on a histologic scale, which may help our understanding of disease progression and treatment response

Hyalocyte origin, structure, and imaging

Hyalocytes have been recognized as resident tissue macrophages of the vitreous body since the mid-19th century. Despite this, knowledge about their origin, turnover, and dynamics is limited. Historically, initial studies on the origin of hyalocytes used light and electron microscopies. Modern investigations across species including rodents and humans will be described. Novel imaging is now available to study human hyalocytes in vivo. The shared ontogeny with retinal microglia and their eventual interdependence as well as differences will be discussed. Owing to a common origin as myeloid cells, hyalocytes and retinal microglia have similarities, but hyalocytes appear to be distinct as resident macrophages of the vitreous body.</p