Narrow-band reflectance spectrophotometry and infrared thermography for assessment of skin lesions in localized scleroderma.

BACKGROUND: Infrared thermography (IRT) is a useful method to detect activity/inflammation in localized scleroderma (LoS); however, inactive skin lesions with a severe degree of dermal and subcutaneous atrophy may show false-positive results. Narrow-band reflectance spectrophotometry (NBRS) is an objective, non-invasive technique of measuring erythema and hyperpigmentation severity, yet has not been extensively studied in LoS. OBJECTIVES: The aim of this research was to compare the spectrophotometric results with thermographic examination of LoS lesions. METHODS: The lesions were assessed using the Localized Scleroderma Assessment Tool (LoSCAT), Dyspigmentation, Induration, Erythema, and Telangiectasias (DIET) score, NBRS and IRT. The difference in the erythema index (ΔEI), melanin index (ΔMI) and average temperature Tavg (ΔTavg) were calculated between each lesion and its normal control. RESULTS: Fifty-five patients with 49 active and 64 inactive LoS lesions were examined. The ΔEI strongly correlated with the erythema (rs = 0.62, P < 0.0000002) and DIET score (rs = 0.66, P < 0.0000001) and moderately correlated with the telangiectasias score (rs = 0.58, P < 0.00001). ΔMI showed strong correlation with the dyspigmentation score (rs = 0.65, P < 0.0000001). There was a strong correlation between the ΔTavg and the erythema score (rs = 0.7, P < 0.000001). A moderate correlation between the Δ EI and ΔTavg was found in active LoS lesions (rs = 0.53, P < 0.0001). CONCLUSION: Narrow-band reflectance spectrophotometry may be a complementary method for determining erythema in LoS active lesions, although this technique remains inferior to IRT, because is unable to distinct between active and inactive lesions. However, NBRS enables to evaluate the severity of hyperpigmentation and telangiectasias, and it can be useful for the assessment of disease severity which is poorly evaluated by IRT.

Lysyl-tRNA synthetase produces diadenosine tetraphosphate to curb STING-dependent inflammation.

Inflammation is an essential part of immunity against pathogens and tumors but can promote disease if not tightly regulated. Self and non-self-nucleic acids can trigger inflammation, through recognition by the cyclic GMP-AMP (cGAMP) synthetase (cGAS) and subsequent activation of the stimulator of interferon genes (STING) protein. Here, we show that RNA:DNA hybrids can be detected by cGAS and that the Lysyl-tRNA synthetase (LysRS) inhibits STING activation through two complementary mechanisms. First, LysRS interacts with RNA:DNA hybrids, delaying recognition by cGAS and impeding cGAMP production. Second, RNA:DNA hybrids stimulate LysRS-dependent production of diadenosine tetraphosphate (Ap4A) that in turn attenuates STING-dependent signaling. We propose a model whereby these mechanisms cooperate to buffer STING activation. Consequently, modulation of the LysRS-Ap4A axis in vitro or in vivo interferes with inflammatory responses. Thus, altogether, we establish LysRS and Ap4A as pharmacological targets to control STING signaling and treat inflammatory diseases.

New markers of insulin resistance in polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is the most common endocrine-metabolic disorder in women of reproductive age. The diagnostic criteria include two out of three features: hyperandrogenism, polycystic ovaries on ultrasound and menstrual irregularities (Rotterdam Criteria 2003). PCOS patients are more vulnerable to develop diabetes, cardiovascular diseases and metabolic syndrome. Insulin resistance (IR) is prevalent in women with PCOS independently of obesity and is critically involved in reproductive and metabolic complications of the syndrome. Several tests have been developed to measure IR, some very reliable but complex like the hyperinsulinemic euglycemic glucose clamp and others less precise but easier and less invasive like HOMA-IR. New markers are needed to reach a more reliable assessment of insulin resistance. To date, several surrogate markers have been proposed in the literature to facilitate and improve the determination of IR. Many new proteins are strongly involved with PCOS physiopathology and IR, such as some adipocytokines (adiponectin, visfatin, vaspin and apelin), copeptin, irisin, PAI-1 and zonulin. Many other proteins have been proposed as potential new markers of IR in PCOS, such as resistin, leptin, RBP4, kisspetin and ghrelin, but their role is still controversial. In this review, we provide a short characterization of these new markers, recently studied as indicators of metabolic state.

Infectious diseases in large-scale cat hoarding investigations.

Animal hoarders accumulate animals in over-crowded conditions without adequate nutrition, sanitation, and veterinary care. As a result, animals rescued from hoarding frequently have a variety of medical conditions including respiratory infections, gastrointestinal disease, parasitism, malnutrition, and other evidence of neglect. The purpose of this study was to characterize the infectious diseases carried by clinically affected cats and to determine the prevalence of retroviral infections among cats in large-scale cat hoarding investigations. Records were reviewed retrospectively from four large-scale seizures of cats from failed sanctuaries from November 2009 through March 2012. The number of cats seized in each case ranged from 387 to 697. Cats were screened for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) in all four cases and for dermatophytosis in one case. A subset of cats exhibiting signs of upper respiratory disease or diarrhea had been tested for infections by PCR and fecal flotation for treatment planning. Mycoplasma felis (78%), calicivirus (78%), and Streptococcus equi subspecies zooepidemicus (55%) were the most common respiratory infections. Feline enteric coronavirus (88%), Giardia (56%), Clostridium perfringens (49%), and Tritrichomonas foetus (39%) were most common in cats with diarrhea. The seroprevalence of FeLV and FIV were 8% and 8%, respectively. In the one case in which cats with lesions suspicious for dermatophytosis were cultured for Microsporum canis, 69/76 lesional cats were culture-positive; of these, half were believed to be truly infected and half were believed to be fomite carriers. Cats from large-scale hoarding cases had high risk for enteric and respiratory infections, retroviruses, and dermatophytosis. Case responders should be prepared for mass treatment of infectious diseases and should implement protocols to prevent transmission of feline or zoonotic infections during the emergency response and when transferring the rescued cats to other shelters or to adopters.

Actin cytoskeleton remodelling by sex steroids in neurones.

Cell morphology and its interaction with the extracellular environment are integrated processes involving a number of intracellular controllers orchestrating cytoskeletal proteins and their interaction with the cell membrane and anchorage proteins. Sex steroids are effective regulators of cell morphology and tissue organisation, and recent evidence indicates that this is obtained through the regulation of the actin cytoskeleton. Intriguingly, many of these regulatory actions related to cell morphology are achieved through the rapid, nonclassical signalling of sex steroid receptors to kinase cascades, independently from nuclear alteration of gene expression or protein synthesis. The identification of the mechanistic basis for these rapid actions on cell cytoskeleton has special relevance for the characterisation of the effects of sex steroids under physiological conditions, such as for the development of neurone/neurone interconnections and dendritic spine density. This is considered to be critical for gender-specific differences in brain function and dysfunction. Recent advancements in the characterisation of the molecular basis of the extranuclear signalling of sex steroids help to clarify the role of oestrogen and progesterone in the brain, and may turn out to be of relevance for clinical purposes. This review highlights the regulatory effects of oestrogens and progesterone on actin cytoskeleton and neurone morphology, as well as recent progresses in the characterisation of these mechanisms, providing insights and working hypotheses on possible clinical applications for the modulation of these pathways in the central nervous system.

Formation of structured nanophases in halide crystals.

When halide crystals KCl and NaCl are slightly doped by PbCl(2), (in orders of 10(-4) mol/mol) the structurally stable nanophases ("quantum dots") are formed via nucleation within the bulks of their matrices. Using lattice modeling we have found in KCl-Pb system natural nucleation pathway from single impurity-vacancy complex to Suzuki phase, not demonstrated in previous analyses; further transition to PbCl(2) is difficult due to high stability of this phase. In the case of NaCl-Pb, no stable "end point" of aggregation was observed and our calculations suggest nucleation may readily proceed to large PbCl(2) clusters when initially formed platelike cluster reaches a certain critical thickness. These results coincide with our experimental data.

Intravitreal bevacizumab (Avastin) for macular oedema secondary to retinal vein occlusion: 12-month results of a prospective clinical trial.

AIMS: The aim of the study was to evaluate functional and anatomical changes after intravitreal bevacizumab (Avastin) in eyes with persistent macular oedema secondary to branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO). METHODS: Twenty-nine consecutive eyes with macular oedema secondary to BRVO (21 eyes) or CRVO (eight eyes) were included in a prospective clinical trial. Eyes were treated with three initial intravitreal bevacizumab injections of 1 mg at a monthly interval. Retreatment was based on central retinal thickness (CRT) based on optical coherence tomography. If continuous injections were indicated up to month 6, the dose was increased to 2.5 mg. RESULTS: After 12 months of follow-up, mean visual acuity increased from 50 letters (20/100) at baseline to 66 letters (20/50(+1); +16 letters; p<0.001) at month 12 and CRT decreased from 558 mum at baseline to 309 mum at month 12 (-249 mum; p<0.001). Patients received a mean of eight out of 13 possible injections. No drug-related systemic or ocular side effects following intravitreal bevacizumab treatment were observed. Fluorescein angiography revealed no progression of avascular areas. CONCLUSIONS: Intravitreal therapy using bevacizumab appears to be a safe and effective treatment in patients with macular oedema secondary to retinal vein occlusion. However, the main limitations of this treatment modality are its short-term effectiveness and high recurrence rate.

Characteristics of severe intraocular inflammation following intravitreal injection of bevacizumab (Avastin).

BACKGROUND/AIMS: To report a series of severe intraocular inflammatory events following intravitreal injections of bevacizumab (Avastin). This procedure is performed on a rapidly increasing number worldwide, and rare complications such as intraocular inflammation, endophthalmitis or intraocular haemorrhage are gaining in importance in clinical routine. METHODS: This is a single-centre retrospective interventional case series of eight patients with severe intraocular inflammation after intravitreal injection of bevacizumab at one referral centre consecutively seen out of approximately a total of 2500 injections performed in that time period. Patients who developed severe intraocular inflammation after intravitreal injection were evaluated clinically, including slit-lamp examination, best-corrected Snellen visual acuity (VA), slit-lamp photography, optical coherence tomography and fluorescein angiography prior to the event and during follow-up. RESULTS: Patients noticed a painless drop in VA up to 2 days following the injection. All patients had a marked anterior chamber reaction with increased flare and cells, but no hypopyon. Typical posterior segment findings included vitreous cellular infiltrates of pseudogranulomatous aspect. Due to their initial clinical aspect suspicious of an endophthalmitis, three cases were treated with systemic antibiotics, but the final diagnosis was uveitis. Five cases showed a characteristic pseudogranulomatous vitreous infiltration as seen in vitritis and were treated only topically. CONCLUSIONS: Characteristic features of an inflammation induced by bevacizumab injection include an early onset with painless loss in VA mostly without conjunctival or ciliary injection. Patients respond to systemic or topical cortisone treatment with slow recovery but without permanent damage. Vitreous haemorrhage and infectious endophthalmitis might be differentiated by time course and symptoms.

Peculiarities of excited state structure and photoluminescence in Bi(3+)-doped Lu(3)Al(5)O(12) single-crystalline films.

Single-crystalline films of Lu(3)Al(5)O(12):Bi, prepared by the liquid phase epitaxy method from the melt-solution based on Bi(2)O(3) flux, have been studied at 4.2-400 K by time-resolved luminescence spectroscopy methods. Their emission spectra consist of two types of bands with strongly different characteristics. The ultraviolet emission band consists of two components, arising from the electronic transitions which correspond to the [Formula: see text] and [Formula: see text] transitions in a free Bi(3+) ion. At low temperatures, mainly the lower-energy component of this emission is observed, having the decay time∼10(-3) s at T<100 K and arising from the metastable (3)P(0) level. At T>100 K, the higher-energy emission component appears, arising from the thermally populated emitting (3)P(1) level. The visible emission spectrum consists of two dominant strongly overlapped broad bands with large Stokes shifts. At 4.2 K, their decay times are ∼10(-5) s and decrease with increasing temperature. Both of the visible emission bands are assumed to have an exciton origin. The lower-energy band is ascribed to an exciton, localized near a single Bi(3+) ion. The higher-energy band shows a stronger intensity dependence on the Bi(3+) content and is assumed to arise from an exciton localized near a dimer Bi(3+) center. The origin and structure of the corresponding excited states is considered and the processes, taking place in the excited states, are discussed.

Reduced fluence versus standard photodynamic therapy in combination with intravitreal triamcinolone: short-term results of a randomised study.

BACKGROUND: To compare early treatment effect of reduced fluence versus standard photodynamic therapy (rPDT, sPDT, respectively) in combination with intravitreal triamcinolone (IVTA) in neovascular age-related macular degeneration. METHODS: Forty patients received either sPDT (group A, n = 20) or rPDT (group B, n = 20) each followed by same-day 4 mg IVTA. Patients were examined at baseline, day 1, week 1, 4 and 12. Main outcomes were visual acuity, central retinal thickness (CRT), choroidal perfusion and macular sensitivity (MS). RESULTS: Baseline characteristics were well balanced in both groups (p>0.05). At week 12, patients in group A had a mean loss of -3.7 letters compared with a gain of 3.4 letters in group B (p = 0.04, between both groups). Both treatment groups showed a similar course regarding CRT as well as MS (p>0.05). In 70% (14/20) of group A and 15% (3/20) of group B, a choroidal hypoperfusion in the area of treatment was observed after treatment (p<0.001). In 70% of group A and 55% of group B, a repeat treatment was indicated at week 12 (p = 0.55). CONCLUSIONS: At month 3, the rPDT+IVTA group showed a significantly better visual outcome, less alteration of the choroid and a trend for lower recurrence rate than the sPDT+IVTA group. Further follow-up of this study will provide information on long-term functional results and treatment durability.

[The role of Stratus OCT in anti-VEGF therapy. Qualitative and quantitative assessment of neovascular AMD]. / Die Rolle des Stratus-OCT bei der Anti-VEGF-Therapie : Qualitative und quantitative Beurteilung bei neovaskulärer AMD.

BACKGROUND: The evaluation of OCT3 during anti-VEGF therapy. METHODS: A total of 29 patients with choroidal neovascularization secondary to AMD received 3 intravitreal injections of ranibizumab. OCT examination and visual acuity testing (ETDRS) were performed before therapy onset, after 1 week and after 1, 2 and 3 months. RESULTS: The central retinal thickness (CRT) was assessed correctly by OCT in 128 out of 145 measurements. There was a distinct (84%) but not significant correlation between decrease in central retinal thickness and increase in visual acuity. Incorrect retinal layer segmentation and inadequate CRT measurements were a significant technical limitation. CONCLUSION: During anti-VEGF therapy, OCT allows documentation and quantification of morphologic retinal changes and in most cases also for an estimation of functional improvement.

[New perspectives in diagnostic. High-resolution optical coherence tomography for age-related macular degeneration]. / Neue Perspektiven in der Diagnostik. Hochauflösende optische Kohärenztomographie bei altersbedingter Makuladegeneration.

BACKGROUND: Recent advances in optical coherence tomography (OCT) have made it possible to increase resolution and scan velocities so that even greater central areas of the retina can be scanned. The aim of this study is to describe the possibilities offered by this new technology for age-related macular degeneration. MATERIAL AND METHODS: The study included 20 patients with confirmed active choroidal neovascularization (CNV) as well as pigment epithelial detachment (PED). Three-dimensional imaging was performed with a high-definition raster scanning OCT system (HD-OCT) with an axial resolution of 6 microm and a scan velocity of up to 20,000 A-scans/s. The scanned area measured 6 x 6 mm with a depth of 2 mm. Two-dimensional imaging was carried out with a StratusOCT (Carl Zeiss Meditec). RESULTS: Comparison of the individual slices showed improved identification of intra- and subretinal structures with the HD-OCT. Demarcation of pathological changes in individual retinal layers is possible with the HD-OCT. Summation images permit accurate localization of a scan. Topographic and volumetric evaluations enable analysis of individual compartments in the entire scanned area and are suitable for monitoring treatment of CNV with anti-VEGF therapy. The raster method decreases the dependence on exploratory methods that have been necessary until now to generate retinal thickness maps. CONCLUSIONS: This report presents initial experience in using a raster scanning HD-OCT system in patients with neovascular age-related macular degeneration and describes new evaluation functions that aid in obtaining more precise assessment of treatment effect and its impact on the retinal ultrastructure. The results of this study clearly show that development of high-resolution OCT systems in conjunction with development of novel treatment options for exudative diseases offers promising perspectives.

Role of breathers in anomalous decay.

We have previously presented evidence for the formation of breathers in doped alkali halides subjected to a flash of UV light. Properties of these breathers, their phase space structure, robustness, decay, and propensity for formation, are studied here. Under a wide range of parameters and interionic potentials they form two-dimensional Kolmogorov-Arnold-Moser tori (less than generic) in phase space. Strobed views of these tori, useful in quantization, are shown. All features support the thesis of breather formation as the explanation for the luminescence decay anomaly that first motivated our breather proposal.

Response of choroidal blood flow to carbogen breathing in smokers and non-smokers.

AIM: To investigate a potential difference in ocular vascular reactivity during carbogen breathing in optic nerve head, choroid, and retina between healthy smokers and non-smokers. METHODS: 25 (13 smokers and 12 non-smokers) healthy male volunteers participated in this observer masked, two cohort study. During inhalation of carbogen (5% CO(2) and 95% O(2)) over 10 minutes measurements were taken using laser Doppler flowmetry to assess submacular choroidal and optic nerve head blood flow, laser interferometry to assess fundus pulsation amplitudes, and retinal vessel analyser (RVA) to assess retinal vessel diameters. RESULTS: At baseline choroidal blood flow was higher (p = 0.018, ANOVA) in smokers than in non-smokers. During administration of carbogen the response in choroidal blood flow was significantly different between the two groups: there was an increase in non-smokers after carbogen breathing (p = 0.048) compared with relatively stable blood flow in smokers (p = 0.049 between groups, ANOVA). A similar response pattern was seen for fundus pulsation amplitude, which increased notably after carbogen breathing in non-smokers but not in smokers (p<0.001 between groups, ANOVA). Optic nerve head blood flow and retinal vessel diameters were reduced in both groups to a comparable degree during carbogen breathing. CONCLUSION: The study indicated abnormal choroidal vascular reactivity in chronic smokers. These early haemodynamic changes may be related to the increased risk to smokers of developing ocular vascular diseases. The specific mechanisms underlying abnormal choroidal vascular reactivity in chronic smokers remain to be characterised.

Twelve hour reproducibility of choroidal blood flow parameters in healthy subjects.

AIMS/BACKGROUND: To investigate the reproducibility and potential diurnal variation of choroidal blood flow parameters in healthy subjects over a period of 12 hours. METHODS: The choroidal blood flow parameters of 16 healthy non-smoking subjects were measured at five time points during the day (8:00, 11:00, 14:00, 17:00, and 20:00). Outcome parameters were pulsatile ocular blood flow as assessed by pneumotonometry, fundus pulsation amplitude as assessed by laser interferometry, blood velocities in the opthalmic and posterior ciliary arteries as assessed by colour Doppler imaging, and choroidal blood flow, volume, and velocity as assessed by fundus camera based laser Doppler flowmetry. The coefficient of variation and the maximum change from baseline in an individual were calculated for each outcome parameter. RESULTS: None of the techniques used found a diurnal variation in choroidal blood flow. Coefficients of variation were within 2.9% and 13.6% for all outcome parameters. The maximum change from baseline in an individual was much higher, ranging from 11.2% to 58.8%. CONCLUSIONS: These data indicate that in healthy subjects the selected techniques provide adequate reproducibility to be used in clinical studies. Variability may, however, be considerably higher in older subjects or subjects with ocular disease. The higher individual differences in flow parameter readings limit the use of the techniques in clinical practice. To overcome problems with measurement validity, a clinical trial should include as many choroidal blood flow outcome parameters as possible to check for consistency.

Choroidal blood flow and arterial blood pressure.

PURPOSE: Untreated hypertension is associated with ocular complications and is a risk factor for the development and progression of vascular ocular pathologies. We set out to investigate the association between systemic blood pressure and choroidal blood flow. METHODS: All subjects were male non-smokers, who did not receive any medication and had normal or slightly elevated blood pressure (systolic blood pressure < or = 160 mmHg; diastolic blood pressure < or = 100 mmHg). The association between systemic blood pressure and fundus pulsation amplitude, a measure of pulsatile choroidal blood flow, was investigated in 318 volunteers. In addition, the association between systemic blood pressure and blood flow velocities in the posterior ciliary arteries supplying the choroid was investigated in these subjects. RESULTS: Ocular fundus pulsation amplitude (r = 0.252; P < 0.001) and mean flow velocity in the posterior ciliary arteries (r = 0.346, P < 0.001) were significantly associated with mean arterial pressure. The correlation of ocular haemodynamic variables with systolic and diastolic blood pressure was in the same range. CONCLUSIONS: Our data indicate a small, but significant increase in choroidal blood flow with increasing blood pressure.

Effect of inhalation of different mixtures of O(2) and CO(2) on retinal blood flow.

AIM: To determine the effects of various mixtures of O(2) and CO(2) on retinal blood flow in healthy subjects. METHODS: A randomised, double masked, four way crossover trial was carried out in 12 healthy male non-smoking subjects. Gas mixtures (100% O(2), 97.5% O(2) + 2.5% CO(2), 95% O(2) + 5% CO(2), and 92% O(2) + 8% CO(2)) were administered for 10 minutes each. Two non-invasive methods were used: laser Doppler velocimetry (LDV) for measurement of retinal blood velocity and fundus imaging with the Zeiss retinal vessel analyser (RVA) for the assessment of retinal vessel diameters. Arterial pH, pCO(2), and pO(2) were determined with an automatic blood gas analysis system. Retinal blood flow through a major temporal vein was calculated. RESULTS: Retinal blood velocity, retinal vessel diameter, and retinal blood flow decreased during all breathing periods (p <0.001 each). Administration of 92% O(2) + 8% CO(2) significantly increased SBP, MAP, and PR (p <0.001 each, versus baseline), whereas the other gas mixtures had little effect on systemic haemodynamics. Addition of 2.5%, 5%, and 8% CO(2) to oxygen caused a marked decrease in pH and an increase in pCO(2) (p <0.001 versus pure oxygen). CONCLUSIONS: Breathing of pure oxygen and oxygen in combination with carbon dioxide significantly decreases retinal blood flow. Based on these data the authors speculate that hyperoxia induced vasoconstriction is not due to changes in intravascular pH and cannot be counteracted by an intravascular increase in pCO(2).

Slow relaxation, confinement, and solitons.

Millisecond crystal relaxation has been used to explain anomalous decay in doped alkali halides. We attribute this slowness to Fermi-Pasta-Ulam solitons. Our model exhibits confinement of mechanical energy released by excitation. Extending the model to long times is justified by its relation to solitons, excitations previously proposed to occur in alkali halides. Soliton damping and observation are also discussed.

Effect of endothelin and BQ123 on ocular blood flow parameters in healthy subjects.

PURPOSE: To characterize the role of the endothelin system in the blood flow control of the optic nerve head and of the choroid in humans. METHODS: Two studies were performed in healthy subjects. Study 1 was a randomized, placebo-controlled, double-masked, balanced, two-way crossover design and study 2 a three way-way crossover design. In study 1 twelve healthy male subjects received endothelin (ET)-1 in stepwise increasing doses of 1.25, 2.5, and 5 ng/kg x min (each infusion step occurred over 20 minutes) coinfused with BQ123 (60 microg/kg x min) or placebo on two different study days. In study 2 twelve healthy male subjects received two doses of BQ123 (60 or 120 microg/kg x min over 60 minutes) or placebo on three different study days. Measurements of optic nerve head blood flow (ONHBF) and choroidal blood flow (ChBF) were performed with laser Doppler flowmetry in both studies. In study 2 mean flow velocity (MFV) of the ophthalmic artery was assessed with Doppler sonography. RESULTS: In study 1, ET-1 significantly decreased ONHBF (-22.8% +/- 4.3% at 5 ng/kg x min, P = 0.003 versus baseline) and ChBF (-21.7% +/- 3.2% at 5 ng/kg x min, P = 0.0001 versus baseline). The effect of the highest administered dose of exogenous ET-1 on ONHBF was significantly attenuated (P = 0.04, ANOVA) by coinfusion of BQ123. Effects of exogenous ET-1 on blood flow (2.5 ng/kg x min ET-1 or higher) also were attenuated in the choroid by coinfusion of BQ123 (ChBF: P = 0.03, ANOVA). In study 2, both dosages of BQ123 significantly increased MFV in the ophthalmic artery (60 microg/kg x min, 12.5% +/- 7.3%; 120 microg/kg x min, 17.2% +/- 9.2%, versus baseline; P = 0.001), but did not change blood flow in the ONH or the choroid. CONCLUSIONS: BQ123 antagonizes the effects of exogenously administered ET-1 on blood flow in the ONH and the choroid. The data indicate, however, that ET-1 does not substantially contribute to the regulation of basal vascular tone in these tissues.

Retinal blood flow and systemic blood pressure in healthy young subjects.

BACKGROUND: The aim of the present study was to investigate the association between systemic blood pressure and retinal blood flow in healthy young subjects. METHODS: Three independent study cohorts were included. A cross-sectional study was performed in 420 young male subjects with systolic blood pressure < 160 mmHg and diastolic blood pressure <100 mmHg. Retinal white blood cell flux (n=210) and blood velocity in the central retinal artery (n=210) were measured. In addition, a longitudinal study was performed in 40 young male subjects in whom retinal and systemic haemodynamic parameters were measured thrice within 6 weeks. Retinal white blood cell flux was measured with the blue-field entoptic technique. Blood flow velocity in the central retinal artery was measured by means of colour Doppler imaging. RESULTS: Retinal white blood cell flux (r=0.262; P<0.001) and mean flow velocity in the central retinal artery (r=0.174, P=0.010) were significantly associated with mean arterial pressure in the cross-sectional study. In the longitudinal study retinal white blood cell flux and mean flow velocity in the central retinal artery were also correlated with systemic blood pressure. CONCLUSIONS: Our data indicate a slight but significant increase in retinal blood flow with blood pressure. Whether this is of clinical relevance in eye diseases with altered retinal perfusion, such as diabetic retinopathy, remains to be established.