Imagen en retromodo para el diagnóstico de drusas del disco óptico: una serie de casos / Retro-mode imaging for the diagnosis of optic disc drusen: A case series

Objetivo: Nuestro principal objetivo es el de comparar la capacidad para detectar las drusas del disco óptico (DDO) utilizando diversas técnicas de imágenes no-invasivas, incluida la novedosa técnica de imagen de retromodo (RMI). Como segundo objetivo analizamos las características morfológicas de las DDO bajo esta última técnica. Materiales y métodos: Este estudio incluyó un total de 7 pacientes con DDO bilaterales, obteniendo un total de 14 ojos analizados. Se utilizaron técnicas no invasivas de imágenes multimodales, que incluyeron fotografía multicolor del fondo de ojo (MC), reflectancia en infrarrojo (NIR), autofluorescencia en luz verde y en luz azul (G-FAF y B-FAF, respectivamente) y RMI. La FAF se utilizó como el método principal para el diagnóstico de DDO. Dos observadores realizaron las comparaciones, obteniendo las tasas de detección de cada uno de los métodos. Las mediciones cuantitativas de las DDO incluyeron el número, el perímetro (P) y el área (A) de las DDO identificadas mediante la técnica de RMI. Resultado: La edad promedio de los pacientes incluidos fue de 49,28±23,16 años; 5 de los 7 pacientes fueron de sexo masculino. La técnica de RMI pudo detectar DDO en todos los casos, con una sensibilidad del 100%, en comparación con MC (sensibilidad del 60,71%), NIR (sensibilidad del 60,71%), B-FAF (sensibilidad del 100%), G-FAF (sensibilidad del 100%). RMI fue la única técnica de imagen capaz de evaluar morfológica y cuantitativamente las DDO. Conclusiones: RMI es una prometedora modalidad no-invasiva de imagen para diagnosticar DDO superficiales, proporcionando información valiosa sobre la distribución, la ubicación y el tamaño de estas. Por lo tanto, mediante nuestros resultados sugerimos la incorporación de la novedosa técnica de RMI como una herramienta complementaria para el diagnóstico y el seguimiento de DDO en combinación con los otros métodos de imagen multimodales.(AU)

Objective: We aimed to compare the detectability of optic disc drusen (ODD), using various non-invasive imaging techniques, including the novel retro-mode imaging (RMI), as well as to analyze the morphological characteristics of ODD on RMI. Methods: This study involved 7 patients with bilateral ODD, totaling 14 eyes. Multimodal imaging techniques, including multicolor fundus photography (MC), near-infrared reflectance (NIR), green and blue light fundus autofluorescence (G-FAF and B-FAF, respectively), and RMI were used to examine the eyes. FAF was used as the primary method of identifying ODD, and each method's detection rate was compared by two observers. Quantitative measurements of ODD included the number of ODD visualized by the RMI technique, the perimeter (P) and area (A) of ODD were identified. Results: The average age of the patients included was 49.28±23.16 years, with 5 of the 7 being men. RMI was able to detect ODD in all cases, with a sensitivity of 100%, compared to MC (sensitivity 60.71%), NIR (sensitivity 60.71%), B-FAF (sensitivity 100%), G-FAF (sensitivity 100%). RMI was the only imaging technique capable of assessing ODD morphology and quantifying ODD. Conclusions: RMI is a promising imaging modality for diagnosing superficial ODD, providing valuable information on the distribution, location, and size of ODD. We suggest the incorporation of RMI as a complementary tool for diagnosing and monitoring ODD in combination with other multimodal imaging methods.(AU)

Imágenes multimodales y retromodo en la calcificación esclerocoroidea: reporte de un caso / Multimodal and retro-mode imaging in sclerochoroidal calcification: A case report

Presentamos un reporte de caso en una paciente de 70años sobre las calcificaciones esclerocoroideas, una rara condición que involucra depósitos de pirofosfato de calcio en el polo posterior del ojo. Proporcionamos un relato sobre la presentación clínica y su apariencia en imágenes multimodales, utilizando fotografías de color del fondo de ojo, tomografía de coherencia óptica de fuente de barrido (SS-OCT), ecografía ocular y la novedosa técnica de retromodo (RMI). Al examen la agudeza visual fue de 20/25 en el ojo derecho y de 20/20 en el ojo izquierdo. La fotografía de color del fondo de ojo reveló depósitos amarillentos localizados en la arcada temporal-superior de ambos ojos. SS-OCT demostró masas de origen escleral. Las ecografías oculares confirmaron la calcificación de estas masas. El RMI detectó imágenes hiperreflectivas con una marcada elevación superficial de las lesiones. El laboratorio sistémico no presentó alteraciones, lo que llevó al diagnóstico de calcificaciones esclerocoroideas bilaterales de origen idiopático.(AU)

We present a case report on sclerochoroidal calcification (SCC), a rare condition involving calcium pyrophosphate deposits in the posterior pole of the eye in a 70-year-old patient. We provide an account of the clinical presentation and its appearance in multimodal images, using color fundus photography, swept-source optical coherence tomography (SS-OCT), ocular ultrasound, and the novel retro-mode imaging (RMI) technique. Visual acuity was 20/25 in the right eye (OD) and 20/20 in the left eye (OS). Color fundus photography revealed yellowish deposits located in the upper temporal arcade of both eyes. SS-OCT demonstrated masses of scleral origin. Ocular ultrasounds confirmed the calcification of these masses. RMI detected hyper-reflective images with marked superficial elevation. Systemic laboratory results did not detect any abnormalities, leading to the diagnosis of bilateral idiopathic SCC.(AU)

Retro-mode imaging for the diagnosis of optic disc drusen: a case series.

OBJECTIVE: We aimed to compare the detectability of optic disc drusen (ODD), using various non-invasive imaging techniques, including the novel retro-mode imaging (RMI), as well as to analyze the morphological characteristics of ODD on RMI. METHODS: This study involved seven patients with bilateral ODD, totaling 14 eyes. Multimodal imaging techniques, including multicolor fundus photography (MC), near-infrared reflectance (NIR), green and blue light fundus autofluorescence (G-FAF and B-FAF, respectively), and RMI were used to examine the eyes. FAF was used as the primary method of identifying ODD, and each method's detection rate was compared by two observers. Quantitative measurements of ODD included the number of ODD visualized by the RMI technique, the perimeter (P) and area (A) of ODD were identified. RESULTS: The average age of the patients included was 49.28 ±â€¯23.16 years, with five of the seven being men. RMI was able to detect ODD in all cases, with a sensitivity of 100%, compared to MC (sensitivity 60.71%), NIR (sensitivity 60.71%), B-FAF (sensitivity 100%), G-FAF (sensitivity 100%). RMI was the only imaging technique capable of assessing ODD morphology and quantifying ODD. CONCLUSIONS: RMI is a promising imaging modality for diagnosing superficial ODD, providing valuable information on the distribution, location, and size of ODD. We suggest the incorporation of RMI as a complementary tool for diagnosing and monitoring ODD in combination with other multimodal imaging methods.

Multimodal and retro-mode imaging in sclerochoroidal calcification: A case report.

We present a case report on sclerochoroidal calcification (SCC), a rare condition involving calcium pyrophosphate deposits in the posterior pole of the eye in a 70-year-old patient. We provide an account of the clinical presentation and its appearance in multimodal images, using color fundus photography, swept-source optical coherence tomography (SS-OCT), ocular ultrasound, and the novel retro-mode imaging (RMI) technique. Visual acuity was 20/25 in the right eye (OD) and 20/20 in the left eye (OS). Color fundus photography revealed yellowish deposits located in the upper temporal arcade of both eyes. SS-OCT demonstrated masses of scleral origin. Ocular ultrasounds confirmed the calcification of these masses. RMI detected hyper-reflective images with marked superficial elevation. Systemic laboratory results did not detect any abnormalities, leading to the diagnosis of bilateral idiopathic SCC.

Mind-to-mind heteroclinic coordination: Model of sequential episodic memory initiation.

Retrieval of episodic memory is a dynamical process in the large scale brain networks. In social groups, the neural patterns, associated with specific events directly experienced by single members, are encoded, recalled, and shared by all participants. Here, we construct and study the dynamical model for the formation and maintaining of episodic memory in small ensembles of interacting minds. We prove that the unconventional dynamical attractor of this process-the nonsmooth heteroclinic torus-is structurally stable within the Lotka-Volterra-like sets of equations. Dynamics on this torus combines the absence of chaos with asymptotic instability of every separate trajectory; its adequate quantitative characteristics are length-related Lyapunov exponents. Variation of the coupling strength between the participants results in different types of sequential switching between metastable states; we interpret them as stages in formation and modification of the episodic memory.

Heteroclinic dynamics of coupled semiconductor lasers with optoelectronic feedback.

Generalized Lotka-Volterra (GLV) equations are important equations used in various areas of science to describe competitive dynamics among a population of N interacting nodes in a network topology. In this Letter, we introduce a photonic network consisting of three optoelectronically cross-coupled semiconductor lasers to realize a GLV model. In such a network, the interaction of intensity and carrier inversion rates, as well as phases of laser oscillator nodes, result in various dynamics. We study the influence of asymmetric coupling strength and frequency detuning between semiconductor lasers and show that inhibitory asymmetric coupling is required to achieve consecutive amplitude oscillations of the laser nodes. These studies were motivated primarily by the dynamical models used to model brain cognitive activities and their correspondence with dynamics obtained among coupled laser oscillators.

Differences in MCT1 A1470T polymorphism prevalence between runners and swimmers.

Skeletal muscle is the major producer and user of lactate in the body. Therefore, transport of lactate across cells' membrane is of considerable importance. Lactate transport is mediated by proton-linked monocarboxylate transporter (MCT1). The A1470T polymorphism (rs1049434) in MCT1 gene influences lactate transport, with T allele associated with reduction of lactate transport rate and elevation in blood lactate levels. The aim of the current study was to compare allelic and genotype frequencies of MCT1 A1470T polymorphism among Israeli track-and-field athletes, swimmers, and non-athletes. Genomic DNA was extracted from 173 track-and-field athletes (age 17-50), 80 swimmers (age 16-49), and 128 non-athletes (age 19-29). Track-and-field athletes were assigned to three subgroups: long-distance runners, middle-distance runners, and power event athletes. Swimmers were assigned to two subgroups: long-distance swimmers and short-distance swimmers. Genotyping was performed using polymerase chain reaction. T-allele frequency was significantly higher among long-distance swimmers (45%) compared with long- and middle-distance runners (27% and 30%, respectively; P < 0.01). In addition, T-allele frequency was significantly higher among short-distance swimmers (40%) compared with power event athletes (25%, P < 0.01). Overall, T-allele frequency was significantly higher among swimmers (42%) compared with runners (27%, P < 0.001). More research is needed to clarify whether this polymorphism displays advantage for swimming performance.

Timing control by redundant inhibitory neuronal circuits.

Rhythms and timing control of sequential activity in the brain is fundamental to cognition and behavior. Although experimental and theoretical studies support the understanding that neuronal circuits are intrinsically capable of generating different time intervals, the dynamical origin of the phenomenon of functionally dependent timing control is still unclear. Here, we consider a new mechanism that is related to the multi-neuronal cooperative dynamics in inhibitory brain motifs consisting of a few clusters. It is shown that redundancy and diversity of neurons within each cluster enhances the sensitivity of the timing control with the level of neuronal excitation of the whole network. The generality of the mechanism is shown to work on two different neuronal models: a conductance-based model and a map-based model.

Computational non-linear dynamical psychiatry: a new methodological paradigm for diagnosis and course of illness.

The goal of this article is to highlight the significant potential benefits of applying computational mathematical models to the field of psychiatry, specifically in relation to diagnostic conceptualization. The purpose of these models is to augment the current diagnostic categories that utilize a "snapshot" approach to describing mental states. We hope to convey to researchers and clinicians that non-linear dynamics can provide an additional useful longitudinal framework to understand mental illness. Psychiatric phenomena are complex processes that evolve in time, similar to many other processes in nature that have been successfully described and understood within deterministic chaos and non-linear dynamic computational models. Dynamical models describe mental processes and phenomena that change over time, more like a movie than a photograph, with multiple variables interacting over time. The use of these models may help us understand why and how current diagnostic categories are insufficient. They may also provide a new, more descriptive and ultimately more predictive approach leading to better understanding of the interrelationship between psychological, neurobiological, and genetic underpinnings of mental illness.

Numerical studies of slow rhythms emergence in neural microcircuits: bifurcations and stability.

There is a growing body of evidence that slow brain rhythms are generated by simple inhibitory neural networks. Sequential switching of tonic spiking activity is a widespread phenomenon underlying such rhythms. A realistic generative model explaining such reproducible switching is a dynamical system that employs a closed stable heteroclinic channel (SHC) in its phase space. Despite strong evidence on the existence of SHC, the conditions on its emergence in a spiking network are unclear. In this paper, we analyze a minimal, reciprocally connected circuit of three spiking units and explore all possible dynamical regimes and transitions between them. We show that the SHC arises due to a Neimark-Sacker bifurcation of an unstable cycle.

[Ethanol production from materials containing cellulose: the potential of approaches developed in Russia].

Development of domestic studies of cellulose-degrading microorganisms and enzymes is reviewed, with emphasis on the prospects of producing ethanol from cellulose materials using cellulolytic enzymes. Domestic research groups leading in the field are presented. A section of the review analyzes problems and prospects of setting up ecologically safe production of motor biofuels from renewable raw materials of plant origin (an approach developed in Russia).

Properties of neutral cellobiose dehydrogenase from the ascomycete Chaetomium sp. INBI 2-26(-) and comparison with basidiomycetous cellobiose dehydrogenases.

The extracellular cellobiose dehydrogenase (CDH) obtained from Chaetomium sp. INBI 2-26(-) has a molecular mass of 95 kDa and an isoelectric point of 5. This novel CDH is highly specific for the oxidation of cellobiose (K(m,app) 4.5 microM) and lactose (K(m,app) 56 microM). With 2,6-dichloroindophenol (DCIP) and cytochrome c(3+) (cyt c(3+)) as electron acceptors, CDH was most active at pH 6. The turnover number of the enzyme for cellobiose, lactose, DCIP and cyt c(3+) was in the range of 9-14s(-1) at 20 degrees C and pH 6. The UV-visible spectrum revealed the flavohemoprotein nature of the enzyme. The cytochrome b domain of the enzyme was reduced by ascorbate, dithionite, as well as specifically by cellobiose in a wide range of pH. The apparent first order rate constants of the spontaneous re-oxidation of the reduced heme domain were estimated as 0.01 and 0.00039 s(-1) at pH 4.5 and 6.5, respectively. The half-inactivation time of CDH at pH 6 and 55 degrees C was ca. 100 min; the stability at pH 8 and, particularly, pH 4 was remarkably lower. Cellobiose stabilized the enzyme against thermal inactivation, whereas DCIP in turn sensitized the enzyme. The new enzyme revealed low affinity for crystalline cellulose, but was capable of binding onto H(3)PO(4)-swollen filter paper. The results show significant differences to already known CDHs and perspectives for several biotechnological applications, where CDH with maximal activity at neutral pH and high affinity for cellobiose and lactose night have some advantages.

Cellulase activity of a haloalkaliphilic anaerobic bacterium, strain Z-7026.

The cellulolytic activity of an alkaliphilic obligate anaerobic bacterium, Z-7026, which was isolated from the microbial community of soda-lake sediments and belongs to the cluster III of Clostridia with low G+C content, was studied. The bacterium was capable of growing in media with cellulose or cellobiose as the sole energy sources. Its maximal growth rate on cellobiose (0.042-0.046 h(-1)) was observed at an initial pH value of 8.5-9.0, whereas the maximal rate of cellulase synthesis, assayed by using a novel fluorimetric approach, was found to be 0.1 h(-1) at pH 8-8.5. Secreted proteins revealed high affinity for cellulose and were represented by two major forms of molecular masses of 75 and 84 kDa, whereas the general protein composition of the precipitated and cellulose-bound preparations was similar to cellulosome subunits of Clostridium thermocellum. The optimum pH of the partially purified enzyme preparation towards both amorphous and crystalline cellulose was in the range 6-9, with more than 70% and less than 50% of maximal activity being retained at pH 9.2 and 5.0, respectively.

Synaptic plasticity with discrete state synapses.

Experimental observations on synaptic plasticity at individual glutamatergic synapses from the CA3 Shaffer collateral pathway onto CA1 pyramidal cells in the hippocampus suggest that the transitions in synaptic strength occur among discrete levels at individual synapses [C. C. H. Petersen, Proc. Natl. Acad. Sci. USA 85, 4732 (1998); O'Connor, Wittenberg, and Wang, D. H. O'Connor, Proc. Natl. Acad. Sci. USA (to be published); J. M. Montgomery and D. V. Madison, Trends Neurosci. 27, 744 (2004)]. This happens for both long term potentiation (LTP) and long term depression (LTD) induction protocols. O'Connor, Wittenberg, and Wang have argued that three states would account for their observations on individual synapses in the CA3-CA1 pathway. We develop a quantitative model of this three-state system with transitions among the states determined by a competition between kinases and phosphatases shown by D. H. O'Connor, to be determinant of LTP and LTD, respectively. Specific predictions for various plasticity protocols are given by coupling this description of discrete synaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor ligand gated ion channel conductance changes to a model of postsynaptic membrane potential and associated intracellular calcium fluxes to yield the transition rates among the states. We then present various LTP and LTD induction protocols to the model system and report the resulting whole cell changes in AMPA conductance. We also examine the effect of our discrete state synaptic plasticity model on the synchronization of realistic oscillating neurons. We show that one-to-one synchronization is enhanced by the plasticity we discuss here and the presynaptic and postsynaptic oscillations are in phase. Synaptic strength saturates naturally in this model and does not require artificial upper or lower cutoffs, in contrast to earlier models of plasticity.

Cellobiose dehydrogenase formation by filamentous fungus Chaetomium sp. INBI 2-26(-).

Laccase-negative filamentous fungus INBI 2-26(-) isolated from non-sporulating laccase-forming fungal association INBI 2-26 by means of protoplast technique was identified as Chaetomium sp. based on partial sequence of its rRNA genes. In the presence of natural cellulose sources, the strain secreted neutral cellobiose dehydrogenase (CDH) activity both in pure culture and in co-culture with laccase-positive filamentous fungus INBI 2-26(+) isolated from the same association. INBI 2-26(-) also secreted CDH during submerged cultivation in minimal medium with glucose as the sole carbon source. Maximal CDH activity of 1IU/ml at pH 6 with 2,6-dichlorophenolindophenol (DCPIP) as an acceptor was obtained on 12th day of submerged cultivation with filter paper as major cellulose source. Cellulase system of Chaetomium sp. INBI 2-26(-) capable of adsorption onto H(3)PO(4)-swollen filter paper consisted of four major proteins (Mr 200, 95, 65 and 55K) based on SDS-polyacrylamide gel electrophoresis and was capable of DCPIP reduction without exogenous cellobiose.

On the origin of reproducible sequential activity in neural circuits.

Robustness and reproducibility of sequential spatio-temporal responses is an essential feature of many neural circuits in sensory and motor systems of animals. The most common mathematical images of dynamical regimes in neural systems are fixed points, limit cycles, chaotic attractors, and continuous attractors (attractive manifolds of neutrally stable fixed points). These are not suitable for the description of reproducible transient sequential neural dynamics. In this paper we present the concept of a stable heteroclinic sequence (SHS), which is not an attractor. SHS opens the way for understanding and modeling of transient sequential activity in neural circuits. We show that this new mathematical object can be used to describe robust and reproducible sequential neural dynamics. Using the framework of a generalized high-dimensional Lotka-Volterra model, that describes the dynamics of firing rates in an inhibitory network, we present analytical results on the existence of the SHS in the phase space of the network. With the help of numerical simulations we confirm its robustness in presence of noise in spite of the transient nature of the corresponding trajectories. Finally, by referring to several recent neurobiological experiments, we discuss possible applications of this new concept to several problems in neuroscience.

Spike timing and synaptic plasticity in the premotor pathway of birdsong.

The neural circuits of birdsong appear to utilize specific time delays in their operation. In particular, the anterior forebrain pathway (AFP) is implicated in an approximately 40- to 50- ms time delay, DeltaT, playing a role in the relative timing of premotor signals from the nucleus HVc to the nucleus robust nucleus of the archistratium (RA) and control/learning signals from the nucleus lateral magnocellular nucleus of the anterior neostratium (lMAN) to RA. Using a biophysical model of synaptic plasticity based on experiments on mammalian hippocampal and neocortical pyramidal neurons, we propose an understanding of this approximately 40- to 50- ms delay. The biophysical model describes the influence of Ca2+ influx into the postsynaptic RA cells through NMDA and AMPA receptors and the induction of LTP and LTD through complex metabolic pathways. The delay, DeltaT, between HVc --> RA premotor signals and lMAN --> RA control/learning signals plays an essential role in determining if synaptic plasticity is induced by signaling from each pathway into RA. If DeltaT is substantially larger than 40 ms, no plasticity is induced. If DeltaT is much less than 40 ms, only potentiation is expected. If DeltaT approximately 40 ms, the sign of synaptic plasticity is sensitive to DeltaT. Our results suggest that changes in DeltaT may influence learning and maintenance of birdsong. We investigate the robustness of this result to noise and to the removal of the Ca2+ contribution from lMAN --> RA NMDA receptors.

Learning classification in the olfactory system of insects.

We propose a theoretical framework for odor classification in the olfactory system of insects. The classification task is accomplished in two steps. The first is a transformation from the antennal lobe to the intrinsic Kenyon cells in the mushroom body. This transformation into a higher-dimensional space is an injective function and can be implemented without any type of learning at the synaptic connections. In the second step, the encoded odors in the intrinsic Kenyon cells are linearly classified in the mushroom body lobes. The neurons that perform this linear classification are equivalent to hyperplanes whose connections are tuned by local Hebbian learning and by competition due to mutual inhibition. We calculate the range of values of activity and size of the network required to achieve efficient classification within this scheme in insect olfaction. We are able to demonstrate that biologically plausible control mechanisms can accomplish efficient classification of odors.

[Degradation of the herbicide atrazine by the soil mycelial fungus INBI 2-26(-)--a producer of cellobiose dehydrogenase]. / Razlozhenie gerbitsida atrazina pochvennym mitselial'nym gribom INBI 2-26(-)--produtsentom tsellobiozodegidrogenazy.

Nonsporulating mycelial fungi producing cellobiose dehydrogenase (CDH) and isolated from soils of South Vietnam with high residual content of dioxins are capable of growing on a solid medium in the presence of high atrazine concentrations (to 500 mg/l). At 20 and 50 mg/l atrazine, the area of fungal colonies was 1.5-1.2-fold larger, respectively, compared with control colonies of the same age, whereas development of the colonies at 500 mg/l atrazine was delayed by 5 days, compared with controls grown in the absence of atrazine. Surface cultivation of the fungus on a minimal medium with glucose as a sole source of carbon and energy decreased the initial concentration of atrazine (20 mg/l) 50 times in 40 days; in addition, no pronounced sorption of atrazine by mycelium was detected. This was paralleled by accumulation in the culture medium of extracellular CDH; atrazine increased the synthesis of this enzyme two- to threefold. Accumulation of beta-glucosidase (a mycelium-associated enzyme) and cellulases preceded the formation of CDH.

[Decomposition of natural aromatic structures and xenobiotics by fungi]. / Razlozhenie prirodnykh aromaticheskikh struktur i ksenobiotikov gribami.

The review deals with transformation of natural and synthetic aromatic compounds by fungi (causative agents of white rot, brown rot, or soft rot, as well as soil filamentous fungi). Major enzyme types involved in the transformation of lignin and aromatic xenobiotics are discussed, with emphasis on activity regulation under the conditions of secondary metabolism and oxidative stress. Coupling of systems degrading polysaccharides/lignin and non-phenolic lignin structures (without the involvement of lignin peroxidase) is analyzed, together with non-enzymatic mechanisms (involving lipoperoxide free radicals, cation-radicals, quinoid mediators, or transition metal ions). Metabolic pathways resulting in the formation of aromatic and haloaromatic compounds in fungi are described. Consideration is given to the mechanisms of fungal adaptation to aromatic xenobiotics.