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Correlação entre as espessuras da mácula e da camada de fibras nervosas da retina, medidas pelas tomografias de coerência óptica de dominio Fourier e de domínio do tempo, e a perimetria automatizada na atrofia em banda do nervo óptico; Correlation between macular and retinal nerve fiber layer Fourier domain and time domain optical coherence tomography measurements and visual field loss in band atrophy of the optic nerve

Cunha, Luciana Virginia Ferreira Costa
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 18/04/2011 PT
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OBJETIVO: Investigar a correlação entre as espessuras da mácula e da camada de fibras nervosas da retina (CFNR), medidas pelas tomografias de coerência óptica de domínio Fourier (FD - OCT) e de domínio do tempo (TD - OCT) e a perda de sensibilidade no campo visual (CV) em pacientes com atrofia em banda do nervo óptico. Comparar a habilidade diagnóstica dos dois instrumentos. MÉTODOS: 36 olhos de 36 pacientes com perda de CV permanente por compressão do quiasma óptico e 36 controles normais foram submetidos ao exame de CV pela perimetria automatizada padrão (Humphrey Field Analyzer TM; Carl Zeiss Meditec, Dublin, CA), ao FD - OCT (3 D OCT-1000TM Topcon Corp., Tokyo, Japan) e ao TD - OCT (StratusTM ;Carl Zeiss Meditec Inc, Dublin, California, USA). Foram comparados os protocolos análogos de ambos os equipamentos para avaliação da espessura macular.Foi realizado a divisão macular em quatro quadrantes e em metades, sendo calculado a média da espessura macular global, a média da espessura dos quadrantes e a média da espessura das metades maculares. A média global e setorial da medida da espessura da CFNR peripapilar também foi analisada. A perda de sensibilidade no CV foi inicialmente avaliada pelo defeito temporal médio. O CV foi ainda dividido em 6 setores de acordo com a distribuição da CFNR e em 16 pontos centrais para a realização da correlação estrutura-função entre os parâmetros medidos pelo FD - OCT e a perda de sensibilidade no CV em decibéis e 1/Lambert. Foi calculado o coeficiente de correlação de Sperman e a análise de regressão linear. As áreas sobre a curva ROC e valores fixos de sensibilidade e especificidade foram calculados para cada parâmetro estudado. RESULTADOS: As medidas da espessura macular e da CFNR pelo FD - OCT e TD - OCT foram capazes de discriminar olhos com atrofia em banda do nervo óptico dos controles normais. A espessura global e setorial dos parâmetros maculares e da CFNR mostraram diferenças significativas (p<0...

Telangiectasia retiniana justafoveolar idiopática do grupo 2A: hiperpigmentação macular incomum em dois pacientes

Bonanomi,Maria Teresa Brizzi C.; Cresta,Fernando Betty; Abujamra,Suel
Fonte: Conselho Brasileiro de Oftalmologia Publicador: Conselho Brasileiro de Oftalmologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2001 PT
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27.17%
Introdução: Telangiectasias retinianas justafoveolares idiopáticas (TJI) do grupo 2A ocorrem na 5ª ou 6ª década de vida, em ambos os sexos. A diminuição da visão está associada a alterações características na mácula que incluem depósitos de pigmento. Objetivo: Descrever dois pacientes com achados incomuns de pigmentação macular. Método: Relato de caso e discussão. Resultados: Observação de grandes placas de pigmento na mácula de dois pacientes. Nos dois casos houve confusão diagnóstica com coriorretinite macular cicatrizada. Em um caso demonstrou-se o aumento da quantidade de pigmento em um período de oito anos. Conclusão: A TJI do grupo 2A pode ser de diagnóstico difícil. A suspeita clínica deve ser feita pelo aspecto característico das placas de pigmento na mácula.

Nitric oxide synthase in macula densa regulates glomerular capillary pressure.

Wilcox, C S; Welch, W J; Murad, F; Gross, S S; Taylor, G; Levi, R; Schmidt, H H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 15/12/1992 EN
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Tubular-fluid reabsorption by specialized cells of the nephron at the junction of the ascending limb of the loop of Henle and the distal convoluted tubule, termed the macula densa, releases compounds causing vasoconstriction of the adjacent afferent arteriole. Activation of this tubuloglomerular feedback response reduces glomerular capillary pressure of the nephron and, hence, the glomerular filtration rate. The tubuloglomerular feedback response functions in a negative-feedback mode to relate glomerular capillary pressure to tubular-fluid delivery and reabsorption. This system has been implicated in renal autoregulation, renin release, and longterm body fluid and blood-pressure homeostasis. Here we report that arginine-derived nitric oxide, generated in the macula densa, is an additional intercellular signaling molecule that is released during tubular-fluid reabsorption and counters the vasoconstriction of the afferent arteriole. Antibody to rat cerebellar constitutive nitric oxide synthase stained rat macula densa cells specifically. Microperfusion of the macula densa segment of single nephrons with N omega-methyl-L-arginine (an inhibitor of nitric oxide synthase) or with pyocyanin (a lipid-soluble inhibitor of endothelium-derived relaxation factor) showed that generation of nitric oxide can vasodilate the afferent arteriole and increase glomerular capillary pressure; this effect was blocked by drugs that prevent tubular-fluid reabsorption. We conclude that nitric oxide synthase in macula densa cells is activated by tubular-fluid reabsorption and mediates a vasodilating component to the tubuloglomerular feedback response. These findings imply a role for arginine-derived nitric oxide in body fluid-volume and blood-pressure homeostasis...

Profile of the genes expressed in the human peripheral retina, macula, and retinal pigment epithelium determined through serial analysis of gene expression (SAGE)

Sharon, Dror; Blackshaw, Seth; Cepko, Constance L.; Dryja, Thaddeus P.
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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We used the serial analysis of gene expression (SAGE) technique to catalogue and measure the relative levels of expression of the genes expressed in the human peripheral retina, macula, and retinal pigment epithelium (RPE) from one or both of two humans, aged 88 and 44 years. The cone photoreceptor contribution to all transcription in the retina was found to be similar in the macula versus the retinal periphery, whereas the rod contribution was greater in the periphery versus the macula. Genes encoding structural proteins for axons were found to be expressed at higher levels in the macula versus the retinal periphery, probably reflecting the large proportion of ganglion cells in the central retina. In comparison with the younger eye, the peripheral retina of the older eye had a substantially higher proportion of mRNAs from genes encoding proteins involved in iron metabolism or protection against oxidative damage and a substantially lower proportion of mRNAs from genes encoding proteins involved in rod phototransduction. These differences may reflect the difference in age between the two donors or merely interindividual variation. The RPE library had numerous previously unencountered tags, suggesting that this cell type has a large...

Macula densa cell signaling involves ATP release through a maxi anion channel

Bell, Phillip Darwin; Lapointe, Jean-Yves; Sabirov, Ravshan; Hayashi, Seiji; Peti-Peterdi, Janos; Manabe, Ken-ichi; Kovacs, Gergely; Okada, Yasunobu
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Macula densa cells are unique renal biosensor cells that detect changes in luminal NaCl concentration ([NaCl]L) and transmit signals to the mesangial cell/afferent arteriolar complex. They are the critical link between renal salt and water excretion and glomerular hemodynamics, thus playing a key role in regulation of body fluid volume. Since identification of these cells in the early 1900s, the nature of the signaling process from macula densa cells to the glomerular contractile elements has remained unknown. In patch–clamp studies of macula densa cells, we identified an [NaCl]L-sensitive ATP-permeable large-conductance (380 pS) anion channel. Also, we directly demonstrated the release of ATP (up to 10 μM) at the basolateral membrane of macula densa cells, in a manner dependent on [NaCl]L, by using an ATP bioassay technique. Furthermore, we found that glomerular mesangial cells respond with elevations in cytosolic Ca2+ concentration to extracellular application of ATP (EC50 0.8 μM). Importantly, we also found increases in cytosolic Ca2+ concentration with elevations in [NaCl]L, when fura-2-loaded mesangial cells were placed close to the basolateral membrane of macula densa cells. Thus, cell-to-cell communication between macula densa cells and mesangial cells...

Evidence for the role of nitric oxide in macula densa control of glomerular hemodynamics.

Ito, S; Ren, Y
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1993 EN
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There is evidence that nitric oxide, an endothelium-derived relaxing factor, may be produced by the macula densa, as well as by blood vessels, within the kidney. To examine the role of nitric oxide in macula densa control of glomerular hemodynamics directly, we performed in vitro microperfusions of both rabbit afferent arterioles (with the glomerulus intact) and adherent tubular segments consisting of portions of the thick ascending limb, macula densa, and early distal tubule. While keeping afferent arteriolar pressure constant at 60 mmHg, we examined the effect of Nw-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthesis, added to a macula densa perfusate. When the macula densa perfusate was changed from low to high NaCl, the diameter of the arterioles decreased from 16.3 +/- 1.0 to 14.0 +/- 1.1 microns (n = 10; P < 0.001). Addition of 10(-5) M L-NAME to the high NaCl solution further decreased the diameter to 11.9 +/- 1.1 microns (P < 0.001). In contrast, when macula densa perfusion was maintained with the low NaCl solution, addition of L-NAME had no effect. L-NAME-induced constriction was completely reversed by adding 10(-3) M L-arginine (the precursor of nitric oxide) but not D-arginine (an inactive isomer) to the macula densa perfusate. We confirmed that perfusing the macula densa with L-NAME did not affect the vasodilator action of acetylcholine added to the lumen of the afferent arteriole...

Potentiation of tubuloglomerular feedback in the rat by thromboxane mimetic. Role of macula densa.

Welch, W J; Wilcox, C S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1992 EN
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27.49%
Because endogenous thromboxane A2 (TXA2) potentiates the tubuloglomerular feedback response (TGF), we studied the mechanism of action of TXA2 by using a stable TXA2/prostaglandin (PG) H2 mimetic, U-46,619. Intravenous infusion of U-46,619 at 100 ng.kg-1.min-1 reduced the GFR and the single-nephron (SN)GFR measured from the distal tubule (macula densa function intact), whereas the SNGFR measured from the proximal tubule (macula densa function interrupted) was not changed consistently. 10-100-fold higher rates of infusion of U-46,619 were required to raise blood pressure or femoral vascular resistance. The regulation of glomerular capillary pressure (PGC) by TGF was assessed in anesthetized rats from changes in proximal stop flow pressure (PSF) and/or SNGFR during perfusion of the loop of Henle (LH) with artificial tubular fluid (ATF). Orthograde loop perfusion and retrograde perfusion of U-46,619 into the macula densa segment reduced PSF. Responses to luminal U-46,619 were blunted by a TXA2-PGH2 receptor antagonist. Orthograde loop perfusions with luminal U-46,619 increased net Cl absorption, whereas coperfusion with furosemide (10(-4) M) blunted the response to U-46,619 by 68%. These data indicated that the luminal U-46,619 might increase the signal for TGF activation by increasing Cl reabsorption in macula densa cells. However...

Basic properties and potential regulators of the apical K+ channel in macula densa cells

Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/06/1994 EN
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27.41%
These studies examine the properties of an apical potassium (K+) channel in macula densa cells, a specialized group of cells involved in tubuloglomerular feedback signal transmission. To this end, individual glomeruli with thick ascending limbs (TAL) and macula densa cells were dissected from rabbit kidney and the TAL covering macula densa cells was removed. Using patch clamp techniques, we found a high density (up to 54 channels per patch) of K+ channels in the apical membrane of macula densa cells. An inward conductance of 41.1 +/- 4.8 pS was obtained in cell-attached patches (patch pipette, 140 mM K+). In inside- out patches (patch pipette, 140 mM; bath, 5 mM K+), inward currents of 1.1 +/- 0.1 pA (n = 11) were observed at 0 mV and single channel current reversed at a pipette potential of -84 mV giving a permeability ratio (PK/PNa) of over 100. In cell-attached patches, mean channel open probability (N,Po, where N is number of channels in the patch and Po is single channel open probability) was unaffected by bumetanide, but was reduced from 11.3 +/- 2.7 to 1.6 +/- 1.3 (n = 5, p < 0.02) by removal of bath sodium (Na+). Simultaneous removal of bath Na+ and calcium (Ca2+) prevented the Na(+)-induced decrease in N.Po indicating that the effect of Na+ removal on N.Po was probably mediated by stimulation of Ca2+ entry. This interpretation was supported by studies where ionomycin...

Intracellular pH regulates superoxide production by the macula densa

Liu, Ruisheng; Carretero, Oscar A.; Ren, Yilin; Wang, Hong; Garvin, Jeffrey L.
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
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We hypothesized that elevated macula densa intracellular pH (pHi) during tubuloglomerular feedback enhances O2− production from NAD(P)H oxidase. Microdissected thick ascending limbs from rabbits with intact macula densa were cannulated and perfused with physiological saline. When luminal NaCl was switched from 10 to 80 mM, O2− production increased from 0.53 ± 0.09 to 2.62 ± 0.54 U/min (P < 0.01). To determine whether inhibiting the Na/H exchanger blocks O2− production, we used dimethyl amiloride (DMA) to block Na/H exchange. In the presence of DMA, O2− production induced by NaCl was blunted by 40%. To study the effect of pHi on O2− in intact macula densa cells, we measured O2− while pHi was changed by adjusting luminal pH. When the macula densa was perfused with 80 mM NaCl and the pH of the perfusate was switched to 6.8, 7.4, and 8.0, O2− production was significantly enhanced, but not at 10 mM NaCl. To ascertain the source of O2−, we used the NAD(P)H oxidase inhibitor apocynin. In the presence of apocynin (10−5 M), O2− production induced by elevating pHi was blocked. Finally, we measured the optimum pH for O2− production by the macula densa and found optimum extracellular pH is at 7.7 and optimum pHi is ∼8 for O2− production. We found that elevated pHi enhances O2− production from NAD(P)H oxidase induced by increasing luminal NaCl when the lumen is perfused with 80 mM NaCl...

Isoforms and Functions of NAD(P)H Oxidase at the Macula Densa

Zhang, Rui; Harding, Pamela; Garvin, Jeffery L.; Juncos, Ramiro; Peterson, Ed; Juncos, Luis A.; Liu, Ruisheng
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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27.41%
Macula densa cells produce superoxide (O2-) during tubuloglomerular feedback primarily via NAD(P)H oxidase (NOX). The purpose of the present study was to determine NOXs expressed by the macula densa, and the role of each one in NaCl-induced O2- production. To identify which isoforms are expressed, we applied single cell RT-PCR to macula densa cells isolated by laser capture microdissection, and to MMDD1 cells (a macula densa-like cell line). The captured cells expressed nNOS (marker of macula densa), NOX2 and NOX4, but not NOX1. Expression of the NOXs and nNOS was essentially identical in the MMDD1 cells. Thus, we used MMDD1 cells to investigate which isoform is responsible for NaCl-induced O2- production. We used siRNA to knock down NOX2 or NOX4 in MMDD1 cells, and measured O2- exposed to low (LS; 70 mM NaCl) or high salt (HS; 140 mM NaCl) solutions. Exposing control cells (scrambled siRNA) to HS increased O2- concentrations from 0.75±0.28 to 1.48±0.46 units/min/105cells in LS and HS, respectively (p<0.001). Inhibiting NOX2 blocked the HS induced increase in O2- (0.62±0.39 vs. 0.76±0.31 units/min/105cells in LS and HS groups, respectively). Blocking NOX4 did not affect HS-induced O2- levels. O2- levels in the control cells during LS and HS were 0.80±0.30 and 1.56 ± 0.49 units/min/105cells...

ATP as a mediator of macula densa cell signalling

Bell, P. Darwin; Komlosi, Peter; Zhang, Zhi-Ren
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.49%
Within each nephro-vascular unit, the tubule returns to the vicinity of its own glomerulus. At this site, there are specialised tubular cells, the macula densa cells, which sense changes in tubular fluid composition and transmit information to the glomerular arterioles resulting in alterations in glomerular filtration rate and blood flow. Work over the last few years has characterised the mechanisms that lead to the detection of changes in luminal sodium chloride and osmolality by the macula densa cells. These cells are true “sensor cells” since intracellular ion concentrations and membrane potential reflect the level of luminal sodium chloride concentration. An unresolved question has been the nature of the signalling molecule(s) released by the macula densa cells. Currently, there is evidence that macula densa cells produce nitric oxide via neuronal nitric oxide synthase (nNOS) and prostaglandin E2 (PGE2) through cyclooxygenase 2 (COX 2)-microsomal prostaglandin E synthase (mPGES). However, both of these signalling molecules play a role in modulating or regulating the macula-tubuloglomerular feedback system. Direct macula densa signalling appears to involve the release of ATP across the basolateral membrane through a maxi-anion channel in response to an increase in luminal sodium chloride concentration. ATP that is released by macula densa cells may directly activate P2 receptors on adjacent mesangial cells and afferent arteriolar smooth muscle cells...

Salt-sensitive splice variant of nNOS expressed in the macula densa cells

Lu, Deyin; Fu, Yiling; Lopez-Ruiz, Arnaldo; Zhang, Rui; Juncos, Ramiro; Liu, Haifeng; Manning, R. Davis; Juncos, Luis A.; Liu, Ruisheng
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
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27.59%
Neuronal nitric oxide synthase (nNOS), which is abundantly expressed in the macula densa cells, attenuates tubuloglomerular feedback (TGF). We hypothesize that splice variants of nNOS are expressed in the macula densa, and nNOS-β is a salt-sensitive isoform that modulates TGF. Sprague-Dawley rats received a low-, normal-, or high-salt diet for 10 days and levels of the nNOS-α, nNOS-β, and nNOS-γ were measured in the macula densa cells isolated with laser capture microdissection. Three splice variants of nNOS, α-, β-, and γ-mRNAs, were detected in the macula densa cells. After 10 days of high-salt intake, nNOS-α decreased markedly, whereas nNOS-β increased two- to threefold in the macula densa measured with real-time PCR and in the renal cortex measured with Western blot. NO production in the macula densa was measured in the perfused thick ascending limb with an intact macula densa plaque with a fluorescent dye DAF-FM. When the tubular perfusate was switched from 10 to 80 mM NaCl, a maneuver to induce TGF, NO production by the macula densa was increased by 38 ± 3% in normal-salt rats and 52 ± 6% (P < 0.05) in the high-salt group. We found 1) macula densa cells express nNOS-α, nNOS-β, and nNOS-γ, 2) a high-salt diet enhances nNOS-β...

Glaucomatous damage of the macula

Hood, Donald C.; Raza, Ali S.; de Moraes, Carlos Gustavo V.; Liebmann, Jeffrey M.; Ritch, Robert
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.36%
There is a growing body of evidence that early glaucomatous damage involves the macula. The anatomical basis of this damage can be studied using frequency domain optical coherence tomography (fdOCT), by which the local thickness of the retinal nerve fiber layer (RNFL) and local retinal ganglion cell plus inner plexiform (RGC+) layer can be measured. Based upon averaged fdOCT results from healthy controls and patients, we show that: 1. For healthy controls, the average RGC+ layer thickness closely matches human histological data; 2. For glaucoma patients and suspects, the average RGC+ layer shows greater glaucomatous thinning in the inferior retina (superior visual field (VF)); and 3. The central test points of the 6° VF grid (24-2 test pattern) miss the region of greatest RGC+ thinning. Based upon fdOCT results from individual patients, we have learned that: 1. Local RGC+ loss is associated with local VF sensitivity loss as long as the displacement of RGCs from the foveal center is taken into consideration; and 2. Macular damage is typically arcuate in nature and often associated with local RNFL thinning in a narrow region of the disc, which we call the macular vulnerability zone (MVZ). According to our schematic model of macular damage...

Testosterone enhances tubuloglomerular feedback by increasing superoxide production in the macula densa

Fu, Yiling; Lu, Yan; Liu, Eddie Y.; Zhu, Xiaolong; Mahajan, Gouri J.; Lu, Deyin; Roman, Richard J.; Liu, Ruisheng
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
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27.28%
Males have higher prevalence of hypertension and renal injury than females, which may be attributed in part to androgen-mediated effects on renal hemodynamics. Tubuloglomerular feedback (TGF) is an important mechanism in control of renal microcirculation. The present study examines the role of testosterone in the regulation of TGF responses. TGF was measured by micropuncture (change of stop-flow pressure, ΔPsf) in castrated Sprague-Dawley rats. The addition of testosterone (10−7 mol/l) into the lumen increased the ΔPsf from 10.1 ± 1.2 to 12.2 ± 1.2 mmHg. To determine whether androgen receptors (AR) are involved, mRNA of AR was measured in the macula dense cells isolated by laser capture microdissection from kidneys, and a macula densa-like cell line (MMDD1). AR mRNA was expressed in the macula densa of rats and in MMDD1 cells. We next examined the effects of the AR blocker, flutamide (10−5 mol/l) on the TGF response. The addition of flutamide blocked the effects of testosterone on TGF. The addition of Tempol (10−4 mol/l) or polyethylene glycol-superoxide dismutase (100 U/ml) to scavenge superoxide blocked the effect of testosterone to augment TGF. We then applied apocynin to inhibit NAD(P)H oxidase and oxypurinol to inhibit xanthine oxidase and found the testosterone-induced augmentation of TGF was blocked. In additional experiments in MMDD1 cells...

A Comparison of Some Organizational Characteristics of the Mouse Central Retina and the Human Macula

Volland, Stefanie; Esteve-Rudd, Julian; Hoo, Juyea; Yee, Claudine; Williams, David S.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 29/04/2015 EN
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27.41%
Mouse models have greatly assisted our understanding of retinal degenerations. However, the mouse retina does not have a macula, leading to the question of whether the mouse is a relevant model for macular degeneration. In the present study, a quantitative comparison between the organization of the central mouse retina and the human macula was made, focusing on some structural characteristics that have been suggested to be important in predisposing the macula to stresses leading to degeneration: photoreceptor density, phagocytic load on the RPE, and the relative thinness of Bruch’s membrane. Light and electron microscopy measurements from retinas of two strains of mice, together with published data on human retinas, were used for calculations and subsequent comparisons. As in the human retina, the central region of the mouse retina possesses a higher photoreceptor cell density and a thinner Bruch’s membrane than in the periphery; however, the magnitudes of these periphery to center gradients are larger in the human. Of potentially greater relevance is the actual photoreceptor cell density, which is much greater in the mouse central retina than in the human macula, underlying a higher phagocytic load for the mouse RPE. Moreover...

Possible role of adenosine in the macula densa mechanism of renin release in rabbits.

Itoh, S; Carretero, O A; Murray, R D
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1985 EN
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27.36%
This study was designed to examine: (a) the effects of adenosine and its analogues on renin release in the absence of tubules, glomeruli, and macula densa, and (b) whether adenosine may be involved in a macula densa-mediated renin release mechanism. Rabbit afferent arterioles (Af) alone and afferent arterioles with macula densa attached (Af + MD) were microdissected and incubated for two consecutive 30-min periods. Hourly renin release rate from a single arteriole (or an arteriole with macula densa) was calculated and expressed as ng AI X h-1 X Af-1 (or Af + MD-1)/h (where AI is angiotensin I). Basal renin release rate from Af was 0.69 +/- 0.09 ng AI X h-1 X Af-1/h (means +/- SEM, n = 16) and remained stable for 60 min. Basal renin release rate from Af + MD was 0.20 +/- 0.04 ng AI X h-1 X Af + MD-1/h (n = 6), which was significantly lower (P less than 0.0025) than that from Af. When adenosine (0.1 microM) was added to Af, renin release decreased from 0.72 +/- 0.16 to 0.24 +/- 0.04 ng AI X h-1 X Af-1/h (P less than 0.025; n = 9). However, when adenosine was added to Af + MD, no significant change in renin release was observed. N6-cyclohexyl adenosine (an A1 adenosine receptor agonist) at 0.1 microM decreased renin release from Af from 0.69 +/- 0.14 to 0.39 +/- 0.12 ng AI X h-1 X Af-1/h (n = 5...

Expression of the Na-K-2Cl cotransporter by macula densa and thick ascending limb cells of rat and rabbit nephron.

Obermüller, N; Kunchaparty, S; Ellison, D H; Bachmann, S
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/08/1996 EN
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27.52%
Sodium and chloride transport by the macula densa and thick ascending limb of Henle's loop participates importantly in extracellular fluid volume homeostasis, urinary concentration and dilution, control of glomerular filtration, and control of renal hemodynamics. Transepithelial Na and Cl transport across the apical membrane of thick ascending limb (TALH) cells is mediated predominantly by a loop diuretic sensitive Na-K-2Cl cotransport pathway. The corresponding transport protein has recently been cloned. Functional studies suggest that the cotransporter is expressed by macula densa cells as well as by TALH cells. The current studies were designed to identify sites of Na-K-2Cl cotransporter expression along distal nephron in rabbit and rat. Non-isotopic high-resolution in situ hybridization, using an antisense probe for the apical form of the Na-K-2Cl cotransporter identified expression throughout the TALH, from the junction between inner and outer medulla to the transition to distal convoluted tubule. Expression by macula densa cells was confirmed by colocalization using markers specific for macula densa cells. First, Na-K-2Cl cotransporter mRNA was detected in macula densa cells that did not stain with anti-Tamm-Horsfall protein antibodies. Second...

Loss of Visual Acuity after Successful Surgery for Macula-On Rhegmatogenous Retinal Detachment in a Prospective Multicentre Study

Di Lauro, Salvatore; Castrejón, Melissa; Fernández, Itziar; Rojas, Jimena; Coco, Rosa M.; Sanabria, María R.; Rodríguez de la Rua, Enrique; Pastor, J. Carlos
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
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27.41%
Purpose. To quantify the frequency of visual loss after successful retinal detachment (RD) surgery in macula-on patients in a multicentric, prospective series of RD. Methods. Clinical variables from consecutive macula-on RD patients were collected in a prospective multicentric study. Visual loss was defined as at least a reduction in one line in best corrected visual acuity (VA) with Snellen chart. The series were divided into 4 subgroups: (1) all macula-on eyes (n = 357); (2) macula-on patients with visual loss at the third month of follow-up (n = 53) which were further subdivided in (3) phakic eyes (n = 39); and (4) pseudophakic eyes (n = 14). Results. Fifty-three eyes (14.9%) had visual loss three months after surgery (n = 39 phakic eyes; n = 14 pseudophakic eyes). There were no statistically significant differences between them regarding their clinical characteristics. Pars plana vitrectomy (PPV) was used in 67.2% of cases, scleral buckle in 57.7%, and scleral explant in 11.9% (36.1% were combined procedures). Conclusions. Around 15% of macula-on RD eyes lose VA after successful surgery. Development of cataracts may be one cause in phakic eyes, but vision loss in pseudophakic eyes could have other explanations such as the effect of released factors produced by retinal ischemia on the macula area. Further investigations are necessary to elucidate this hypothesis.

Anatomy and development of the macula: specialisation and the vulnerability to macular degeneration

Provis, Jan; Penfold, Philip; Cornish, Elisa E; Sandercoe, Trent M; Madigan, Michelle
Fonte: Australian Optometrical Association Publicador: Australian Optometrical Association
Tipo: Artigo de Revista Científica
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The central retina in primates is adapted for high acuity vision. The most significant adaptations to neural retina in this respect are: 1. The very high density of cone photoreceptors on the visual axis; 2. The dominance of Midget pathways arising from these cones and 3. The diminishment of retinal blood supply in the macula, and its absence on the visual axis. Restricted blood supply to the part of the retina that has the highest density of neural elements is paradoxical. Inhibition of vascular growth and proliferation is evident during foetal life and results in metabolic stress in ganglion cells and Mü;ller cells, which is resolved during formation of the foveal depression. In this review we argue that at the macula stressed retinal neurons adapt during development to a limited blood supply from the choriocapillaris, which supplies little in excess of metabolic demand of the neural retina under normal conditions. We argue also that while adaptation of the choriocapillaris underlying the foveal region may initially augment the local supply of oxygen and nutrients by diffusion, in the long term these adaptations make the region more vulnerable to age-related changes, including the accumulation of insoluble material in Bruch's membrane and beneath the retinal pigment epithelium. These changes eventually impact on delivery of oxygen and nutrients to the RPE and outer neural retina because of reduced flow in the choriocapillaris and the increasing barriers to effective diffusion. Both the inflammatory response and the sequelae of oxidative stress are predictable outcomes in this scenario.

Desprendimiento seroso de mácula como manifestación atípica en la enfermedad del arañazo del gato

Asensio-Sánchez,V.M.; Rodríguez-Delgado,B.; García-Herrero,E.; Cabo-Vaquera,V.; García-Loygorri,C.
Fonte: Archivos de la Sociedad Española de Oftalmología Publicador: Archivos de la Sociedad Española de Oftalmología
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/12/2006 SPA
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Caso clínico: Paciente de 58 años con una agudeza visual de 0,1 en el ojo izquierdo asociada a un desprendimiento seroso de la mácula como única manifestación ocular de la enfermedad del arañazo del gato. El diagnóstico se realizó con estudios serológicos y por la evolución clínica. Discusión: Aunque es poco frecuente, la enfermedad del arañazo del gato debería considerarse en el diagnóstico diferencial del desprendimiento seroso de mácula.