Retinal ultrastructural findings in cone degeneration

We studied an eye from a 73-year-old man with a sporadic type of retinal cone degeneration and choroidal melanoma. Histologic and ultrastructural studies of the nasal retina unaffected by the choroidal melanoma showed alterations at the outer retina predominantly involving the photoreceptors and retinal pigment epithelium. A wide spectrum of pathologic changes were observed, ranging from near normal retina showing only photoreceptor outer segment disease (distortion and kinking) to grossly pathologic regions where photoreceptor cell bodies were sparse and their outer segments absent. The retinal pigment epithelium in minimally affected regions of the retina showed an increased proportion of the melanin complement of the cell within complex granules. In severe disease, many cells showed only giant complex granules with no free melanin. Retinal pigment epithelial cell migration and relocation around blood vessels was also noted in severe disease.

Endocytosis in the retinal and choroidal microcirculation

The endocytosis of horseradish peroxidase (HRP) by the vascular cells of retinal and choroidal blood vessels was compared in immersion and perfusion fixed eyes from individual rats. The mechanisms of endocytosis of HRP appeared identical in both retinal and choroidal vessels. The bulk of internalised tracer occurred in macropinosomes 300-400 nm in diameter. Tracer was localised to a 20-30 nm layer on the internal aspect of the limiting membrane. This layer was coincident with the glycocalyx of the luminal plasma membrane as revealed by ruthenium redosmium tetroxide staining. Horseradish peroxidase was also internalised by a small scattered population of vesicles (100-130 nm in diameter). The size of these vesicles suggested that they may have arisen from clathrin coated regions of the plasma membrane. It is suggested that the endocytosis of HRP in retinal and choroidal vascular endothelium occurs as a function of plasma membrane recycling. Horseradish peroxidase may also be internalised as a 'contaminant' of the glycocalyx in coated pits involved in receptor mediated endocytosis. The smooth 80 nm plasmalemmal caveolae of the retinal and choroidal vascular endothelial cells did not appear to participate either in absorptive endocytosis or vesicular transport.

Does unidirectional vesicular transport occur in retinal vessels?

This paper challenges the hypothesis that the smooth 80 nm plasmalemmal caveolae found in abundance at the abluminal aspect of the endothelium in retinal blood vessels participate in a unidirectional vesicular transport mechanism. Evidence is presented which indicates that horseradish peroxidase, when introduced to the extracellular space of the retina via the vitreous body, may enter the intravascular compartment through junctional incompetence which occurs at or after enucleation of the eye. It is proposed that the plasmalemmal caveolae at the abluminal plasma membrane of endothelial cells in retinal blood vessels are static structures which facilitate the transport of small solutes and ions across the blood retinal barrier.

A morphologic and autoradiographic study of cell death and regeneration in the retinal microvasculature of normal and diabetic rats

Cell loss and regeneration were investigated and compared in the retinal microvasculature of age- and sex-matched normal and streptozotocin diabetic rats. Selective pericyte loss in the diabetic rat was characterized by changes in the pericyte to endothelial cell ratio in retinal capillaries isolated for microscopy by the trypsin digest technique. A comparison of 3- and 9-month-old normal rats showed no significant change in the pericyte to endothelial cell ratio (1:2.7). In diabetic animals the ratio was reduced to 1:4.03, which was statistically significant (P less than .001). Premitotic retinal vascular cells in normal and diabetic rats were labelled with tritiated thymidine and the labelling indices calculated from cell counts of trypsin digest preparations. Methyl H3 thymidine was infused continuously over an eight-day period using osmotic mini pumps. The labelling index of endothelial cells (0.33%) in normal rats increased to 0.91% in diabetic animals (P less than .05). The labelling index of pericyte cells in normal animals (0.16%) did not increase significantly (P greater than .05) in diabetic animals (0.19%). A special stain was used to exclude labelled polymorphonuclear leukocytes from the cell counts.

An ultrastructural study of retinal photoreceptor degeneration associated with bronchial carcinoma

We studied both eyes of a 66-year-old man with retinal degeneration and oat cell carcinoma of the bronchus. Retinal degeneration was most marked peripheral to the parafovea where photoreceptor cells and their outer segments were absent. Within the parafovea, photoreceptor cells remained but rod outer segments were absent and cone outer segments were fragmented and disorganized. The retinal pigment epithelium contained many immature melanin granules within melanolysosomes, suggesting abnormal melanin synthesis and resorption. We suggest that a pharmacologically active substance resembling a hormone produced by the tumor increased melanin synthesis in the pigment epithelium and that the increased melanin content in these cells compromised their ability to phagocytose and maintain normal turnover of photoreceptor outer segments. We believe these changes led to photoreceptor outer segment loss and subsequent degeneration of the photoreceptor cells.

Antibodies to the structural polypeptides of measles virus following acute infection and in SSPE

A solid-phase radioimmunoassay was used to determine the specificity of IgG antibodies from normal sera, sera and CSF from patients with SSPE for the structural polypeptides of measles virus. The polypeptide specificity of antibodies from these sources were qualitatively similar; these results indicate antigenic cross-reactivity between SSPE-derived (Mantooth) and non-SSPE-derived strains of measles virus and stimulation of antibody formation by comparable antigens.

Low molecular weight measles immunoglobulin M in subacute sclerosing panencephalitis and acute measles

Thirty eight patients with subacute sclerosing panencephalitis (SSPE) were investigated. Five patients who previously had measles immunoglobulin M (IgM) detected in unfractionated serum and cerebrospinal fluid (CSF) had measles IgM exclusively in the low molecular weight (LMW) fractions of serum and CSF. Measles IgM had previously not been found in unfractionated serum from 33 patients but was detected exclusively in the LMW fractions of serum from 30 patients. Seven children with acute measles had the expected high molecular weight (HMW) measles IgM in serum but 5 also had LMW measles IgM. Four young adults who had had measles in childhood had neither HMW nor LMW measles IgM in their sera.

Testing a model for developing, implementing and evaluating a strategy to improve the quality of nursing and midwifery care in an acute hospital trust.

Abstract:
Background: Health care organisations
worldwide are faced with the need to develop
and implement strategic organisational plans
to meet the challenges of modern health care.
There is a need for models for developing, implementing and evaluating strategic plans that engage practitioners, and make a measurable difference to the patients that they serve. These presentations describe the development, implementation and evaluation of such a model by a team of senior nurses and practice developers, to underpin a strategy for nursing and midwifery in an acute hospital trust. Developing a Strategy The PARIHS (Promoting Action on Research Implementation in Health Services) conceptual framework (Kitson et al, 1998) proposes that successful implementation of change in practice is a function of the interplay of three core elements: the level of evidence supporting the proposed change; the context or environment in which the change takes place, and the way in which change is facilitated. We chose to draw on this framework to develop our strategy and implementation plan (O’Halloran, Martin and Connolly, 2005). At the centre of the plan are ward managers. These professionals provide leadership for the majority of staff in the trust and so were seen to be a key group in the implementation process.

Retinal vascular geometry predicts incident renal dysfunction in young people with type 1 diabetes

OBJECTIVE - To examine the relationship between retinal vascular geometry parameters and development of incident renal dysfunction in young people with type 1 diabetes. RESEARCH DESIGN AND METHODS - This was a prospective cohort study of 511 adolescents with type 1 diabetes of at least 2 years duration, with normal albumin excretion rate (AER) and no retinopathy at baseline while attending an Australian tertiary-care hospital. AER was quantified using three overnight, timed urine specimen collections and early renal dysfunction was defined as AER >7.5 µg/min. Retinal vascular geometry (including length-to-diameter ratio [LDR] and simple tortuosity [ST]) was quantified from baseline retinal photographs. Generalized estimating equations were used to examine the relationship between incident renal dysfunction and baseline venular LDR and ST, adjusting for age, diabetes duration, glycated hemoglobin (A1C), blood pressure (BP), BMI, and cholesterol. RESULTS - Diabetes duration at baseline was 4.8 (IQR 3.3-7.5) years. After amedian 3.7 (2.3-5.7) years follow-up, 34% of participants developed incident renal dysfunction. In multivariate analysis, higher retinal venular LDR (odds ratio 1.7, 95% CI 1.2-2.4; quartile 4 vs. 1-3) and lower venular ST (1.6, 1.1-2.2; quartile 1 vs. 2-4) predicted incident renal dysfunction. CONCLUSIONS - Retinal venular geometry independently predicted incident renal dysfunction in young people with type 1 diabetes. These noninvasive retinal measures may help to elucidate early mechanistic pathways for microvascular complications. Retinal venular geometry may be a useful tool to identify individuals at high risk of renal disease early in the course of diabetes. © 2012 by the American Diabetes Association.