scholarly journals Accurate Optic Disc and Cup Segmentation from Retinal Images Using a Multi-Feature Based Approach for Glaucoma Assessment

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1267 ◽  
Author(s):  
Yuan Gao ◽  
Xiaosheng Yu ◽  
Chengdong Wu ◽  
Wei Zhou ◽  
Xiaonan Wang ◽  
...  
Keyword(s):  
Optic Disc ◽  
Single Channel ◽  
Automatic Segmentation ◽  
Critical Role ◽  
Image Space ◽  
Image Clustering ◽  
Vessel Occlusion ◽  
Multiple Channel ◽  
Complex Anatomy ◽  
Contour Evolution

Accurate optic disc (OD) and optic cup (OC) segmentation play a critical role in automatic glaucoma diagnosis. In this paper, we present an automatic segmentation technique regarding the OD and the OC for glaucoma assessment. First, the robust adaptive approach for initializing the level set is designed to increase the performance of contour evolution. Afterwards, in order to handle the complex OD appearance affected by intensity inhomogeneity, pathological changes, and vessel occlusion, a novel model that integrates ample information of OD with the effective local intensity clustering (LIC) model together is presented. For the OC segmentation, to overcome the segmentation challenge as the OC’s complex anatomy location, a novel preprocessing method based on structure prior information between the OD and the OC is designed to guide contour evolution in an effective region. Then, a novel implicit region based on modified data term using a richer form of local image clustering information at each point of interest gathered over a multiple-channel feature image space is presented, to enhance the robustness of the variations found in and around the OC region. The presented models symmetrically integrate the information at each point in a single-channel image from a multiple-channel feature image space. Thus, these models correlate with the concept of symmetry. The proposed models are tested on the publicly available DRISHTI-GS database and the experimental results demonstrate that the models outperform state-of-the-art methods.

scholarly journals Inhibition of Vascular Nitric Oxide after Rat Chronic Brain Hypoperfusion: Spatial Memory and Immunocytochemical Changes

2005 ◽  
Vol 25 (6) ◽  
pp. 663-672 ◽  
Author(s):  
Jack C. de la Torre ◽  
Gjumrakch Aliev
Keyword(s):  
Nitric Oxide ◽  
Spatial Memory ◽  
Memory Function ◽  
Critical Role ◽  
Artery Occlusion ◽  
Carotid Artery Occlusion ◽  
Significant Loss ◽  
Electron Microscopic ◽  
Vessel Occlusion ◽  
Common Carotid Artery Occlusion

An aging rat model of chronic brain hypoperfusion (CBH) that mimics human mild cognitive impairment (MCI) was used to examine the role of nitric oxide synthase (NOS) isoforms on spatial memory function. Rats with CBH underwent bilateral common carotid artery occlusion (2-vessel occlusion (2-VO)) for either 26 or 8 weeks and were compared with nonoccluded sham controls (S-VO). The neuronal and endothelial (nNOS/eNOS) constitutive inhibitor nitro-L-arginine methyl ester (L-NAME) 20 mg/kg was administered after 26 weeks for 3 days to 2-VO and S-VO groups and spatial memory was assessed with a modified Morris watermaze test. Only 2-VO rats worsened their spatial memory ability after L-NAME. Electron microscopic immunocytochemical examination using an antibody against eNOS showed 2-VO rats had significant loss or absence of eNOS-containing positive gold particles in hippocampal endothelium and these changes were associated with endothelial cell compression, mitochondrial damage and heavy amyloid deposition in hippocampal capillaries and perivascular region. In the 8-week study, three groups of 2-VO rats were administered an acute dose of 7-NI, aminoguanidine or L-NIO, the relatively selective inhibitors of nNOS, inducible NOS and eNOS. Only rats administered the eNOS inhibitor L-NIO worsened markedly their watermaze performance ( P=0.009) when compared with S-VO nonoccluded controls. We conclude from these findings that vascular nitric oxide derived from eNOS may play a critical role in spatial memory function during CBH possibly by keeping cerebral perfusion optimal through its regulation of microvessel tone and cerebral blood flow and that disruption of this mechanism can result in spatial memory impairment. These findings may identify therapeutic targets for preventing MCI and treating Alzheimer's disease.

scholarly journals ANALISIS KINERJA SISTEM ANTRIAN DALAM MENGOPTIMALKAN PELAYANAN PASIEN RAWAT JALAN DI RSUD HAJI MAKASSAR

2018 ◽  
Vol 14 (3) ◽  
pp. 228-238
Author(s):  
Maat Pono
Keyword(s):  
Single Channel ◽  
Multiple Channel ◽  
Query System

Tujuan dari penelitian ini untuk mengetahui kinerja sistem antrian yang saat ini digunakan oleh RSUD Haji Makassar. Berdasarkan hasil penelitian, model antrian yang saat ini diterapkan pada bagian registrasi pasien rawat jalan di RSUD Haji Makassar menunjukkan kinerja yang belum begitu baik pada loket pendaftaran, adapun model yang saat ini digunakan adalah sistem antrian model jalur tunggal atau Single Channel Query System (M/M/1). Berdasarkan hasil observasi dan perhitungan menggunakan rumus dari model (M/M/1) diketahui pasien lama membutuhkan waktu berada dalam antrian adalah selama 57,27 menit serta orang dalam antrian sebanyak 21 orang dan ini terjadi pada periode waktu 09.00-10.00 sampai 10.00-11.00. Untuk pasien baru membutuhkan waktu berada dalam antrian selama 50 menit dan jumlah orang dalam antrian sebanyak 5 orang dan ini terjadi pada periode waktu 09.00-10.00 sampai 11.00-12.00. Alternatif yang dapat menangani masalah pada loket pendaftaran adalah dengan merubah komposisi server dengan menggunakan Multiple Channel Query System (M/M/s) melalui model ini waktu yang dibutuhkan pasien lama didalam antrian menurun menjadi 0,8 menit, serta pasien lama dalam antrian yang awalnya 21 orang menjadi 1,24 orang, dengan alternatif ini kinerja sistem antrian dapat lebih optimal.

scholarly journals A molecular link between activation and inactivation of sodium channels.

1995 ◽  
Vol 106 (4) ◽  
pp. 641-658 ◽  
Author(s):  
M E O'Leary ◽  
L Q Chen ◽  
R G Kallen ◽  
R Horn
Keyword(s):  
Sodium Channels ◽  
Voltage Dependence ◽  
Single Channel ◽  
Critical Role ◽  
Channel Measurements ◽  
Wild Type ◽  
Open Probability ◽  
Voltage Dependent ◽  
Steady State Inactivation ◽  
Normal Coupling

A pair of tyrosine residues, located on the cytoplasmic linker between the third and fourth domains of human heart sodium channels, plays a critical role in the kinetics and voltage dependence of inactivation. Substitution of these residues by glutamine (Y1494Y1495/QQ), but not phenylalanine, nearly eliminates the voltage dependence of the inactivation time constant measured from the decay of macroscopic current after a depolarization. The voltage dependence of steady state inactivation and recovery from inactivation is also decreased in YY/QQ channels. A characteristic feature of the coupling between activation and inactivation in sodium channels is a delay in development of inactivation after a depolarization. Such a delay is seen in wild-type but is abbreviated in YY/QQ channels at -30 mV. The macroscopic kinetics of activation are faster and less voltage dependent in the mutant at voltages more negative than -20 mV. Deactivation kinetics, by contrast, are not significantly different between mutant and wild-type channels at voltages more negative than -70 mV. Single-channel measurements show that the latencies for a channel to open after a depolarization are shorter and less voltage dependent in YY/QQ than in wild-type channels; however the peak open probability is not significantly affected in YY/QQ channels. These data demonstrate that rate constants involved in both activation and inactivation are altered in YY/QQ channels. These tyrosines are required for a normal coupling between activation voltage sensors and the inactivation gate. This coupling insures that the macroscopic inactivation rate is slow at negative voltages and accelerated at more positive voltages. Disruption of the coupling in YY/QQ alters the microscopic rates of both activation and inactivation.

scholarly journals A Single P-loop Glutamate Point Mutation to either Lysine or Arginine Switches the Cation–Anion Selectivity of the CNGA2 Channel

2006 ◽  
Vol 127 (4) ◽  
pp. 375-389 ◽  
Author(s):  
Wei Qu ◽  
Andrew J. Moorhouse ◽  
Meenak Chandra ◽  
Kerrie D. Pierce ◽  
Trevor M. Lewis ◽  
...  
Keyword(s):  
Point Mutation ◽  
Single Channel ◽  
Noise Analysis ◽  
Critical Role ◽  
Reversal Potential ◽  
Site Directed Mutagenesis ◽  
Hek293 Cells ◽  
Single Point Mutation ◽  
Cation Selectivity ◽  
Anion Selectivity

Cyclic nucleotide-gated (CNG) channels play a critical role in olfactory and visual transduction. Site-directed mutagenesis and inside-out patch-clamp recordings were used to investigate ion permeation and selectivity in two mutant homomeric rat olfactory CNGA2 channels expressed in HEK293 cells. A single point mutation of the negatively charged pore loop (P-loop) glutamate (E342) to either a positively charged lysine or arginine resulted in functional channels, which consistently responded to cGMP, although the currents were generally extremely small. The concentration–response curve of the lysine mutant channel was very similar to that of wild-type (WT) channels, suggesting no major structural alteration to the mutant channels. Reversal potential measurements, during cytoplasmic NaCl dilutions, showed that the lysine and the arginine mutations switched the selectivity of the channel from cations (PCl/PNa = 0.07 [WT]) to anions (PCl/PNa = 14 [Lys] or 10 [Arg]). Relative anion permeability sequences for the two mutant channels, measured with bi-ionic substitutions, were NO3− > I− > Br− > Cl− > F− > acetate−, the same as those obtained for anion-selective GABA and glycine channels. The mutant channels also seem to have an extremely small single-channel conductance, measured using noise analysis of about 1–2 pS, compared to a WT value of about 29 pS. The results showed that it is predominantly the charge of the E342 residue in the P-loop, rather than the pore helix dipoles, which controls the cation–anion selectivity of this channel. However, the outward rectification displayed by both mutant channels in symmetrical NaCl solutions suggests that the negative ends of the pore helix dipoles may play a role in reducing the outward movement of Cl− ions through these anion-selective channels. These results have potential implications for the determinants of anion–cation selectivity in the large family of P-loop–containing channels.

Effects of Expansion Algorithms on Speech Reception Thresholds

2008 ◽  
Vol 19 (02) ◽  
pp. 147-157 ◽  
Author(s):  
Christi L. Wise ◽  
Justin A. Zakis
Keyword(s):  
Hearing Aids ◽  
Single Channel ◽  
Multiple Channel ◽  
Low Level ◽  
Speech Reception ◽  
Average Spectrum ◽  
Channel Expansion ◽  
The Difference ◽  
Speech Reception Thresholds ◽  
The Impact

Expansion is commonly used to reduce microphone noise and low-level environmental noises that can be annoying to hearing aid users. It may also improve or reduce the perception of low-level speech. This study assessed the impact of two expansion algorithms, single and multiple channel, on speech reception thresholds (SRT) with 10 hearing impaired listeners wearing hearing aids with ADRO® processing. The single-channel algorithm suppressed sounds below 45 dB A, while the multiple-channel algorithm suppressed sounds below the long-term average spectrum of speech at either 55 or 45 dB SPL. The mean HINT SRTs in quiet were 39.4, 40.7, 40.6, and 41.8 dB A without expansion, with single-channel expansion, and with multiple-channel expansion at expansion thresholds of 45 and 55 dB SPL, respectively. The difference in mean SRT was only statistically significant between no expansion and multiple-channel expansion at a 55 dB SPL threshold. A regression analysis between the change in individual SRT for each expansion condition and pure tone average hearing loss showed no correlation. Our calculations indicate that only those with exceptionally good hearing will find microphone noise audible. The current practice of prescribing expansion algorithms based on hearing thresholds alone is questioned, and other rationales are discussed. La expansión se utiliza comúnmente para reducir el ruido de los micrófonos y los ruidos ambientales de bajo nivel que pueden ser perturbadores para los usuarios de auxiliares auditivos. También puede mejorar o reducir la percepción de lenguaje a bajo voumen. Este estudio evaluó el impacto de dos algoritmos de expansión, de canal múltiple y el canal único, sobre los umbrales de recepción del lenguaje (SRT) con 10 sujetos hipoacúsicos utilizando auxiliares auditivos con procesamiento ADRO®. El algoritmo de canal único suprimió sonidos por debajo de 45 dB A, mientras que el algoritmo de canal múltiple suprimió sonidos por debajo del espectro promedio a largo plazo del lenguaje, a 55 ó 45 dB SPL, respectivamente. La diferencia en el SRT medio fue sólo estadísticamente significativa entre la no expansión y la expansión de canal múltiple a un umbral de 55 dB SPL. Un análisis de regresión no mostró correlación entre el cambio en los SRT individuales para cada condición de expansión y la pérdida auditiva promedio para tonos puros. Nuestros cálculos indican que solamente aquellos con una audición excepcionalmente buena encontrarán audible el ruido del micrófono. Se cuestiona la práctica actual de prescribir algoritmos de expansión con base sólo en umbrales auditivos, y se discuten otros razonamientos.

scholarly journals Increased thrombogenesis and embolus formation in mice lacking glycoprotein V

Blood ◽  
2001 ◽  
Vol 98 (2) ◽  
pp. 368-373 ◽  
Author(s):  
Heyu Ni ◽  
Vanitha Ramakrishnan ◽  
Zaverio M. Ruggeri ◽  
Jessie M. Papalia ◽  
David R. Phillips ◽  
...  
Keyword(s):  
Vascular Injury ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Critical Role ◽  
Wild Type ◽  
Vessel Occlusion ◽  
High Affinity Binding Site ◽  
Time Required ◽  
Von Willebrand

The glycoprotein (GP) Ib-V-IX complex plays a critical role in initiating platelet adhesion to von Willebrand factor (vWF) at the site of vascular injury. The complex also forms a high-affinity binding site for thrombin. Using an intravital microscopy mouse model, it was previously established that vWF plays a critical role in mediating platelet adhesion and thrombus formation following mesenteric arteriolar injury induced by ferric chloride. Further characterization of this model showed that these thrombotic events were also thrombin dependent. Using this vWF- and thrombin-dependent model, this study shows that GP V gene deficiency significantly accelerates both platelet adhesion and thrombus formation in mice following arteriolar injury. The time required for vessel occlusion in GP V–deficient (GP V−/−) mice was significantly shorter than that in wild-type mice. Interestingly, large emboli were also produced in GP V−/− mice, but not in wild-type mice, causing frequent downstream occlusion. However, when the 2 genotypes were compared in the in vitro perfusion chamber where thrombin was inhibited by heparin, no significant differences were found in either initial single-platelet adhesion or thrombus volume. These results demonstrate that GP V−/− mice have accelerated thrombus growth in response to vascular injury and suggest that this is caused by enhanced thrombin-induced platelet activation rather than enhanced binding of GPIb-V-IX to vWF. Absence of GP V also compromises thrombus stability.

scholarly journals Hemodynamics of Leptomeningeal Collaterals after Large Vessel Occlusion and Blood Pressure Management with Endovascular Treatment

2021 ◽  
Vol 23 (3) ◽  
pp. 343-357
Author(s):  
Beom Joon Kim ◽  
Nishita Singh ◽  
Bijoy K. Menon
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Endovascular Treatment ◽  
Critical Role ◽  
Intravenous Thrombolysis ◽  
Large Vessel ◽  
Large Vessel Occlusion ◽  
Vessel Occlusion ◽  
Pial Arteries ◽  
Research Perspectives

Endovascular therapy (EVT) is an effective treatment for ischemic stroke due to large vessel occlusion (LVO). Unlike intravenous thrombolysis, EVT enables visualization of the restoration of blood flow, also known as successful reperfusion in real time. However, until successful reperfusion is achieved, the survival of the ischemic brain is mainly dependent on blood flow from the leptomeningeal collaterals (LMC). It plays a critical role in maintaining tissue perfusion after LVO via pre-existing channels between the arborizing pial small arteries or arterioles overlying the cerebral hemispheres. In the ischemic territory where the physiologic cerebral autoregulation is impaired and the pial arteries are maximally dilated within their capacity, the direction and amount of LMC perfusion rely on the systemic perfusion, which can be estimated by measuring blood pressure (BP). After the EVT procedure, treatment focuses on mitigating the risk of hemorrhagic transformation, potentially via BP reduction. Thus, BP management may be a key component of acute care for patients with LVO stroke. However, the guidelines on BP management during and after EVT are limited, mostly due to the scarcity of high-level evidence on this issue. In this review, we aim to summarize the anatomical and physiological characteristics of LMC to maintain cerebral perfusion after acute LVO, along with a landscape summary of the literature on BP management in endovascular treatment. The objective of this review is to describe the mechanistic association between systemic BP and collateral perfusion after LVO and thus provide clinical and research perspectives on this topic.

Automatic segmentation of optic disc and cup for CDR calculation

2019 ◽  
Vol 15 (5) ◽  
pp. 381-385 ◽  
Author(s):  
Xin Zhao ◽  
Fan Guo ◽  
Bei-ji Zou ◽  
Rong-chang Zhao
Keyword(s):  
Optic Disc ◽  
Automatic Segmentation

scholarly journals Inhibition of MicroRNA-96 Ameliorates Cognitive Impairment and Inactivation Autophagy Following Chronic Cerebral Hypoperfusion in the Rat

2018 ◽  
Vol 49 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Peifang Liu ◽  
Peijia Liu ◽  
Zhiyong Wang ◽  
Shaohong Fang ◽  
Yuting Liu ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Critical Role ◽  
Beclin 1 ◽  
Chronic Cerebral Hypoperfusion ◽  
Cerebral Hypoperfusion ◽  
Vessel Occlusion ◽  
Protein Levels ◽  
Culture Cells ◽  
High Risk Factor ◽  
Underlying Mechanisms

Background/Aims: Chronic cerebral hypoperfusion (CCH) is a high-risk factor for vascular dementia and Alzheimer’s disease. Autophagy plays a critical role in the initiation and progression of CCH. However, the underlying mechanisms remain unclear. In this study, we identified the effect of a microRNA (miR) on autophagy under CCH. Methods: A CCH rat model was established by two-vessel occlusion (2VO). Learning and memory abilities were assessed by the Morris water maze. The protein levels of LC3, beclin-1, and mTOR were detected by western blotting and immunofluorescence assays, miR-96 expression was assessed by real-time PCR, luciferase assays were used to determine the effect of miR-96 on the 3′ untranslated region (UTR) of mTOR, and the number of autophagosomes was examined by electron microscopy. Results: The level of miR-96 was significantly increased in 2VO rats, and inhibition of miR-96 ameliorated the cognitive impairment induced by 2VO. Furthermore, the number of LC3- and beclin-1-positive autophagosomes was increased in 2VO rats, and was decreased after miR-96 antagomir injection. However, the protein level of mTOR was reduced in 2VO rats, and it was down-regulated by miR-96 overexpression and up-regulated by miR-96 inhibition in 2VO rats and primary culture cells. Moreover, the luciferase activity of the 3′-UTR of mTOR was suppressed by miR-96, which was relieved by mutation of the miR-96 binding sites. Conclusion: Our study demonstrated that miR-96 may play a key role in autophagy under CCH by regulating mTOR; therefore, miR-96 may represent a potential therapeutic target for CCH.

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