Regional variation in peripapillary retinal blood flow in primary open angle glaucoma:a follow-up study

Purpose: To investigate whether regional long-term changes in peripapillary retinal flow, measured by scanning laser Doppler flowmetry (SLDF), occur in patients with primary open angle glaucoma (POAG). Methods: 31 healthy volunteers (mean age: 65 8.3 years) and 33 POAG patients (mean age: 71.2 7.6 years) were followed up every 4 months for 16 months. Using SLDF, three images of the superior and inferior optic nerve head were obtained for each subject. A 1010-pixel frame was used to measure blood flow, volume and velocity in the four quadrants of the peripapillary retina. Central 24-2 visual field testing was carried out at each visit. Repeated measures analysis of covariance was used to assess change over time between the normal and POAG groups for the SLDF parameters. Univariate linear regression analysis for mean deviation and glaucoma change probability (GCP) analysis were used to identify visual field progression. Results: Blood volume, flow and velocity measured in the inferior nasal quadrant of the peripapillary retina decreased significantly over time for the POAG group compared to the normal group (p=0.0073, 0.0097, 0.0095 respectively). Overall, 2 glaucoma patients showed a significantly deteriorating MD slope, while 7 patients showed visual field progression with GPA. All of the patients progressing with GPA, showed change in the superior hemifield and, of those, 14% showed change in the inferior hemifield. Conclusion: Glaucoma patients showed a decrease in blood flow, volume and velocity in the inferior nasal peripapillary retina. A regional variation in microvascular retinal capillary blood flow may provide insight into the pathogenesis of glaucomatous optic neuropathy. Keywords: 331 blood supply • 554 retina • 624 visual fields

Retinal vascular dysfunction relates to cognitive impairment in Alzheimer's disease

Cerebral vascular dysregulation has been increasingly implicated as a risk factor in the development of Alzheimer disease (AD)1; however, because of the difficulties associated with assessing and visualizing the cerebral vasculature directly, the ability to detect such dysregulation, noninvasively, is currently limited.2 Consequently, one concept that is being increasingly explored is the possibility of using the eye as a "window to the brain"; this approach has reasonable scientific validity as the retinal and brain vessels share a large number of embryological, anatomic, and functional similarities.2 Indeed, previous research has demonstrated a correlation between cognition and the geometry of the retinal vessels in elderly people.3 The aim of this pilot study, therefore, was to explore whether microvascular functional anomalies are evident at the retinal level in mild AD patients and to determine whether these anomalies relate to the degree of concurrent cognitive deficit..

Improving brain drug targeting through exploitation of the nose-to-brain route:a physiological and pharmacokinetic perspective

With an ageing population and increasing prevalence of central-nervous system (CNS) disorders new approaches are required to sustain the development and successful delivery of therapeutics into the brain and CNS. CNS drug delivery is challenging due to the impermeable nature of the brain microvascular endothelial cells that form the blood-brain barrier (BBB) and which prevent the entry of a wide range of therapeutics into the brain. This review examines the role intranasal delivery may play in achieving direct brain delivery, for small molecular weight drugs, macromolecular therapeutics and cell-based therapeutics, by exploitation of the olfactory and trigeminal nerve pathways. This approach is thought to deliver drugs into the brain and CNS through bypassing the BBB. Details of the mechanism of transfer of administrated therapeutics, the pathways that lead to brain deposition, with a specific focus on therapeutic pharmacokinetics, and examples of successful CNS delivery will be explored. © 2014 Bentham Science Publishers.

Oxidised LDL lipids, statins and a blood-brain barrier

Elevated cholesterol in mid-life has been associated with increased risk of dementia in later life. We have previously shown that low density lipoprotein (LDL) is more oxidised in the plasma of dementia patients although total cholesterol levels remained unchanged. Increased systemic oxidative modification (oxLDL) and nitration is also observed during hypercholesterolemia. We have investigated the hypothesis that disruption of blood brain barrier (BBB) function by oxLDL and their lipids may increase risk of neurodegeneration in later life and that statin intervention can mitigate the effects of hyperlipidaemia in mid-life. LDL isolated from statin-naïve hypercholesterolaemic subjects had higher mobility by agarose gel electrophoresis (Rf;0.53±0.06) and 8-isoprostane F2α concentration (43.5±8.42pg/ml) compared to control subjects (Rf; 0.46±0.05 and 24.2±5.37pg/ml respectively; p<0.05). Compared to HMVEC treatment with the LDL-lipids (5μM) from normolipidaemic subjects, LDL-lipids from hypercholesterolaemic subjects increased barrier permeability (103.4±12.5 Ωcm2 v 66.7±7.3 Ωcm2,P<0.01) and decreased cellular glutathione levels (18.5nmol/mg v 12.3nmol/mg) compared to untreated cells (26.2±3.6nmol/mg). LDL-lipids isolated from normolipidaemic subjects shows reduced risk to damage a BBB model compared with LDL-lipids from hypercholesterolaemic subjects. Moreover, a three month statin-intervention reduced the propensity for LDL-lipids from subjects with hyperlipidaemia to damage HMVEC. Post-statin treatment the cytotoxic and pro-inflammatory effects of LDL lipids disappeared. These data support the hypothesis that in vivo intervention with statins modifies LDL lipid oxidation, exerting a protective effect against in microvascular damage independent of cholesterol concentration.

Psychotic symptoms are associated with physical health problems independently of a mental disorder diagnosis:results from the WHO World Health Survey

This study explored whether physical health problems are related to psychotic symptoms independently of a mental disorder diagnosis. A total of 224,254 subjects recruited for the World Health Organization World Health Survey were subdivided into those with both a lifetime diagnosis of psychosis and at least one psychotic symptom in the 12 months prior to the evaluation, those with at least one psychotic symptom in the past 12 months but no lifetime diagnosis of psychosis, and those without psychotic symptoms in the past 12 months and without a lifetime diagnosis of psychosis. The three groups were compared for the presence of medical conditions, health problems, and access to health care. Medical conditions and health problems (angina, asthma, arthritis, tuberculosis, vision or hearing problems, mouth/teeth problems, alcohol consumption, smoking, and accidents), medication consumption, and hospital admissions (but not regular health care visits) were more frequent in individuals with psychotic symptoms but no psychosis diagnosis, compared to those with no symptoms and no diagnosis. The number of medical conditions increased with the number of psychotic symptoms. Given the sample analyzed, this trend seems to be independent from the socio-economic development of the country or the specific health care system.

Work disability and depressive disorders:impact on the European population

OBJECTIVE: Our aim was to study the impact of depressive disorders on work disability to discover the determinants of depression for work disability in the European countries. DESIGN: The sample was composed of 31,126 individuals from 29 countries included in the 2002 World Health Survey of the World Health Organization. National representative samples of countries from all regions of Europe and with different levels of economic development and health coverage were selected. RESULTS: Estimates of people not working because of ill health did not differ among European countries in relation to levels of economic development or health coverage. Significant determinants of people with diagnosis of depression not working because of ill health (reference category) versus working were age (odds ratio = 0.97), female sex (odds ratio = 1.71), education (odds ratio = 1.11), marital status (being unmarried indicating less probability), lowest income level, and comorbidity with angina pectoris (odds ratio = 0.51). Moreover, according to previous studies, we found some determinants (comorbidity with other diseases, young age, and unemployment) impacting on health status. CONCLUSIONS: Depression is a substantial cause of work disability and it is a complex phenomenon that involves many variables. Investigation into this relationship should improve, focusing on the role of determinants.

Modified lipids from LDL in the blood during mid-life increase blood brain barrier permeability

Low density lipoprotein levels (LDL) are consistently elevated in cardiovascular disease. It has been suggested that those with high circulating LDL levels in mid-life may be susceptible to develop neurodegenerative diseases in later life. In the circulation, high levels of LDL are associated with increased oxidative modification (oxLDL) and nitration. We have investigated the hypothesis that disruption of blood brain barrier function by oxLDL and their lipids may increase risk of neurodegeneration in later life and that statin intervention in mid-life can mitigate the neurodegenerative effects of hyperlipidaemia. Blood from statin-naïve, normo- and hyperlipidaemic subjects (n=10/group) was collected at baseline. Hyperlipidaemic subjects received statin-intervention whereas normolipidaemic subjects did not prior to a second blood sampling, taken after 3 months. The intervention will be completed in June 2013. Plasma was separated by centrifugation (200g, 30min) and LDL was isolated by potassium bromide density gradient ultracentrifugation. Total homocysteine, LDL cholesterol, 8-isoprostane F2α levels were measured in plasma using commercial kits. LDL were analysed by agarose gel electrophoresis. LDL-lipids were extracted by partitioning in 1:1 chloroform:methanol (v/v) and conjugated to fatty acid free-BSA in serum-free EGM-2 medium (4hrs, 370C) for co-culture with human microvascular endothelial cells (HMVEC). HMVEC were maintained on polycarbonate inserts for two weeks to create a microvascular barrier. Change in barrier permeability was measured by trans-endothelial electrical resistance (TER), FITC-dextran permeability and immunohistochemistry. HMVEC glutathione (GSH) levels were measured after 2 hours by GSH-glo assay. LDL isolated from statin-naïve hyperlipidaemic subjects had higher mobility by agarose gel electrophoresis (Rf;0.53±0.06) and plasma 8-isoprostane F2α (43.5±8.42 pg/ml) compared to control subjects (0.46±0.05 and 24.2±5.37 pg/ml; p<0.05). Compared to HMVEC treatment with the LDL-lipids (5μM) from normolipidaemic subjects, LDL-lipids from hyperlipidaemic subjects increased barrier permeability (103.4±12.5 Ωcm2 v 66.7±7.3 Ωcm2,P<0.01) and decreased GSH (18.5 nmol/mg v 12.3 nmol/mg; untreated cells 26.2±3.6 nmol/mg).

Retinal vascular function and cardiovascular risk factors

The current platform of conventional cardiovascular risk assessments tends to forsake the importance of endothelial function - a key biological mechanism by which cardiovascular risk factors exert their propensity for adverse vascular events. Moreover, the presence and severity of endothelial dysfunction in ‘low-risk’ individuals suggests considerable variability in pre-clinical risk that could potentially be detected well before the onset of disease. The aim of the present thesis was to investigate the presence and impact of retinal vascular dysfunction, as a barometer of endothelial function, in otherwise healthy individuals with one or more cardiovascular risk factors, but low to moderate cardiovascular risk. Systemic circulatory influences on retinal vascular function were also evaluated. The principle sections and findings of this work are: 1. Ageing effect on retinal vascular function • In low-risk individuals, there are age differences in retinal vascular function throughout the entire functional response curve for arteries and veins. Gender differences mainly affect the dilatory phase and are only present in young individuals. 2. Retinal vascular function in healthy individuals with a family history of cardiovascular disease • In low-risk individuals with a family history of cardiovascular disease, impairments in microvascular function at the retinal level correlate with established plasma markers for cardiovascular risk. 3. Ethnic differences in retinal vascular function • When compared to age-matched White Europeans, in low-risk middle-aged South Asians, there are impairments in retinal vascular function that correlate with established cardiovascular risk indicators. 4. Systemic circulatory influences on retinalµvascular function • Systemic antioxidant capacity (redox index) and plasma markers for cardiovascular risk (lipids) influence retinal microvascular function at both arterial and venous levels. 5. Retinal vascular function in individuals with obstructive sleep apnoea: a preliminarystudy • Patients with moderate to severe sleep apnoea exhibit attenuated retinal vascular function.

The relationship of systemic markers of renal function and vascular function with retinal blood vessel responses

Purpose: To test the hypothesis of a significant relationship between systemic markers of renal and vascular function (processes linked to cardiovascular disease and its development) and retinal microvascular function in diabetes and/or cardiovascular disease.Methods: Ocular microcirculatory function was measured in 116 patients with diabetes and/or cardiovascular disease using static and continuous retinal vessel responses to three cycles of flickering light. Endothelial function was evaluated by von Willebrand factor (vWf), endothelial microparticles and soluble E selectin, renal function by serum creatinine, creatinine clearance and estimated glomerular filtration rate (eGFR). HbA1c was used as a control index.Results: Central retinal vein equivalence and venous maximum dilation to flicker were linked to HbA1c (both p<0.05). Arterial reaction time was linked to serum creatinine (p=0.036) and eGFR (p=0.039), venous reaction time was linked to creatinine clearance (p=0.018). Creatinine clearance and eGFR were linked to arterial maximum dilatation (p<0.001 and p=0.003 respectively) and the dilatation amplitude (p=0.038 and p=0.048 respectively) responses in the third flicker cycle. Of venous responses to the first flicker cycle, HbA1c was linked to the maximum dilation response (p=0.004) and dilatation amplitude (p=0.017), vWf was linked to the maximum constriction response (p=0.016), and creatinine clearance to the baseline diameter fluctuation (p=0.029). In the second flicker cycle, dilatation amplitude was linked to serum creatinine (p=0.022). Conclusions: Several retinal blood vessel responses to flickering light are linked to glycaemia and renal function, but only one index is linked to endothelial function. Renal function must be considered when interpreting retinal vessel responses.

Risk factors of coronary heart disease and correlates of type 2 diabetes among Cuban Americans

Cuban Americans, a minority Hispanic subgroup, have a high prevalence of type 2 diabetes. Persons with diabetes experience a higher rate of coronary heart disease (CHD) compared to those without diabetes. The objectives of the National Institute of Diabetes and Digestive and Kidney Disease (NIDDK) are to investigate the risk factors of CHD and the etiology of diabetes among diabetics of minority ethnic populations. No information is available on the etiology of CHD risks for Cuban Americans. ^ This cross-sectional study compared Cuban Americans with (N = 79) and without (N = 80) type 2 diabetes residing in South Florida. Data on risk factors of CHD and type 2 diabetes were collected using sociodemographics, smoking habit, Rose Angina, Modifiable Activity, and Willet's food frequency questionnaires. Anthropometrics and blood pressure (BP) were recorded. Glucose, glycated hemoglobin, lipid profile, homocysteine, and C-reactive protein were assessed in fasting blood. ^ Diabetics reported a significantly higher rate of angina symptoms than non-diabetics (P = 0.008). After adjusting for age and gender, diabetics had significantly (P < 0.001) larger waist circumference and higher systolic BP than non-diabetics. There was no significant difference in major nutrient intakes between the groups. One quarter of subjects, both diabetics and non-diabetics, exceeded the intake of percent calories from total fat and almost 60% had cholesterol intake >200 mg/d and more than 60% had fiber intake <20 gm/d. The pattern of physical activity did not differ between groups though, it was much below the recommended level. After adjusting for age and gender, diabetics had significantly (P < 0.001) higher levels of blood glucose, glycated hemoglobin, triglycerides, and homocysteine than non-diabetics. In contrast, diabetics had significantly (P < 0.01) lower levels of high-density lipoprotein cholesterol (HDL-C). ^ Multivariate logistic regression analyses showed that increasing age, male gender, large waist circumference, lack of acculturation, and high levels of triglycerides were independent risk factors of type 2 diabetes. In contrast, moderate alcohol consumption conferred protection against diabetes. ^ The study identified several risk factors of CHD and diabetes among Cuban Americans. Health care providers are encouraged to practice ethno-specific preventive measures to lower the burden of CHD and diabetes in Cuban Americans. ^

Specific Increase in MDR1 Mediated Drug-Efflux in Human Brain Endothelial Cells following Co-Exposure to HIV-1 and Saquinavir

Persistence of HIV-1 reservoirs within the Central Nervous System (CNS) remains a significant challenge to the efficacy of potent anti-HIV-1 drugs. The primary human Brain Microvascular Endothelial Cells (HBMVEC) constitutes the Blood Brain Barrier (BBB) which interferes with anti-HIV drug delivery into the CNS. The ATP binding cassette (ABC) transporters expressed on HBMVEC can efflux HIV-1 protease inhibitors (HPI), enabling the persistence of HIV-1 in CNS. Constitutive low level expression of several ABC-transporters, such as MDR1 (a.k.a. P-gp) and MRPs are documented in HBMVEC. Although it is recognized that inflammatory cytokines and exposure to xenobiotic drug substrates (e.g HPI) can augment the expression of these transporters, it is not known whether concomitant exposure to virus and anti-retroviral drugs can increase drug-efflux functions in HBMVEC. Our in vitro studies showed that exposure of HBMVEC to HIV-1 significantly up-regulates both MDR1 gene expression and protein levels; however, no significant increases in either MRP-1 or MRP-2 were observed. Furthermore, calcein-AM dye-efflux assays using HBMVEC showed that, compared to virus exposure alone, the MDR1 mediated drug-efflux function was significantly induced following concomitant exposure to both HIV-1 and saquinavir (SQV). This increase in MDR1 mediated drug-efflux was further substantiated via increased intracellular retention of radiolabeled [3H-] SQV. The crucial role of MDR1 in 3H-SQV efflux from HBMVEC was further confirmed by using both a MDR1 specific blocker (PSC-833) and MDR1 specific siRNAs. Therefore, MDR1 specific drug-efflux function increases in HBMVEC following co-exposure to HIV-1 and SQV which can reduce the penetration of HPIs into the infected brain reservoirs of HIV-1. A targeted suppression of MDR1 in the BBB may thus provide a novel strategy to suppress residual viral replication in the CNS, by augmenting the therapeutic efficacy of HAART drugs.

Theoretical Investigation of Intra- and Inter-cellular Spatiotemporal Calcium Patterns in Microcirculation

Microcirculatory vessels are lined by endothelial cells (ECs) which are surrounded by a single or multiple layer of smooth muscle cells (SMCs). Spontaneous and agonist induced spatiotemporal calcium (Ca2+) events are generated in ECs and SMCs, and regulated by complex bi-directional signaling between the two layers which ultimately determines the vessel tone. The contractile state of microcirculatory vessels is an important factor in the determination of vascular resistance, blood flow and blood pressure. This dissertation presents theoretical insights into some of the important and currently unresolved phenomena in microvascular tone regulation. Compartmental and continuum models of isolated EC and SMC, coupled EC-SMC and a multi-cellular vessel segment with deterministic and stochastic descriptions of the cellular components were developed, and the intra- and inter-cellular spatiotemporal Ca2+ mobilization was examined. Coupled EC-SMC model simulations captured the experimentally observed localized subcellular EC Ca2+ events arising from the opening of EC transient receptor vanilloid 4 (TRPV4) channels and inositol triphosphate receptors (IP3Rs). These localized EC Ca2+ events result in endothelium-derived hyperpolarization (EDH) and Nitric Oxide (NO) production which transmit to the adjacent SMCs to ultimately result in vasodilation. The model examined the effect of heterogeneous distribution of cellular components and channel gating kinetics in determination of the amplitude and spread of the Ca2+ events. The simulations suggested the necessity of co-localization of certain cellular components for modulation of EDH and NO responses. Isolated EC and SMC models captured intracellular Ca2+ wave like activity and predicted the necessity of non-uniform distribution of cellular components for the generation of Ca2+ waves. The simulations also suggested the role of membrane potential dynamics in regulating Ca2+ wave velocity. The multi-cellular vessel segment model examined the underlying mechanisms for the intercellular synchronization of spontaneous oscillatory Ca2+ waves in individual SMC. From local subcellular events to integrated macro-scale behavior at the vessel level, the developed multi-scale models captured basic features of vascular Ca2+ signaling and provide insights for their physiological relevance. The models provide a theoretical framework for assisting investigations on the regulation of vascular tone in health and disease.

Characterization of engineered human lung tissue

Characterizing engineered human lung tissue is an important step in developing a functional tissue replacement for lung tissue repair and in vitro analysis. Small tissue constructs were grown by seeding IMR-90 fetal lung fibroblasts and adult microvascular endothelial cells onto a Polyglycolic acid (PGA) polymer template. Introducing the constructs to dynamic culture conditions inside a bioreactor facilitated three-dimensional growth seen in scanning electron microscopy images (SEM). Characterization of the resultant tissue samples was done using SEM imagery, tensile tests, and biochemical assays to quantify extra-cellular matrix (ECM) composition. Tensile tests of the engineered samples indicated an increase in the mechanical properties when compared with blank constructs. Elastin and collagen content was found to average 3.19% and 15.49% respectively in relation to total mass of the tissue samples. The presence of elastin and collagen within the constructs most likely explains the mechanical differences that we noted. These findings suggest that the necessary ECM can be established in engineered tissue constructs and that optimization of this procedure has the capacity to generate the load bearing elements required for construction of a functional lung tissue equivalent.

Avaliação imunoistoquímica de CD34 e triptase em cistos odontogênicos radiculares e cistos dentígeros inflamados

Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq

Avaliação imunoistoquímica de CD34 e triptase em cistos odontogênicos radiculares e cistos dentígeros inflamados

Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq