34 research outputs found
Ageing as a price of cooperation and complexity: Self-organization of complex systems causes the ageing of constituent networks
The analysis of network topology and dynamics is increasingly used for the description of the structure, function and evolution of complex systems. Here we summarize key aspects of the evolvability and robustness of the hierarchical network-set of macromolecules, cells, organisms, and ecosystems. Listing the costs and benefits of cooperation as a necessary behaviour to build this network hierarchy, we outline the major hypothesis of the paper: the emergence of hierarchical complexity needs cooperation leading to the ageing of the constituent networks. Local cooperation in a stable environment may lead to over-optimization developing an ‘always-old’ network, which ages slowly, and dies in an apoptosis-like process. Global cooperation by exploring a rapidly changing environment may cause an occasional over-perturbation exhausting system-resources, causing rapid degradation, ageing and death of an otherwise ‘forever-young’ network in a necrosis-like process. Giving a number of examples we explain how local and global cooperation can both evoke and help successful ageing. Finally, we show how various forms of cooperation and consequent ageing emerge as key elements in all major steps of evolution from the formation of protocells to the establishment of the globalized, modern human society. Thus, ageing emerges as a price of complexity, which is going hand-in-hand with cooperation enhancing each other in a successful community
Disordered proteins and network disorder in network descriptions of protein structure, dynamics and function. Hypotheses and a comprehensive review
During the last decade, network approaches became a powerful tool to describe protein structure and dynamics. Here we review the links between disordered proteins and the associated networks, and describe the consequences of local, mesoscopic and global network disorder on changes in protein structure and dynamics. We introduce a new classification of protein networks into ‘cumulus-type’, i.e., those similar to puffy (white) clouds, and ‘stratus-type’, i.e., those similar to flat, dense (dark) low-lying clouds, and relate these network types to protein disorder dynamics and to differences in energy transmission processes. In the first class, there is limited overlap between the modules, which implies higher rigidity of the individual units; there the conformational changes can be described by an ‘energy transfer’ mechanism. In the second class, the topology presents a compact structure with significant overlap between the modules; there the conformational changes can be described by ‘multi-trajectories’; that is, multiple highly populated pathways. We further propose that disordered protein regions evolved to help other protein segments reach ‘rarely visited’ but functionally-related states. We also show the role of disorder in ‘spatial games’ of amino acids; highlight the effects of intrinsically disordered proteins (IDPs) on cellular networks and list some possible studies linking protein disorder and protein structure networks
Szabadgyök-felszabadulĂĄs vizsgĂĄlata femtoszekundum lĂ©zerrel asszisztĂĄlt capsulotomiĂĄt követĆen | Evaluation of free radical quantity in the anterior chamber following femtosecond laser-assisted capsulotomy
Absztrakt
Bevezetés: A femtoszekundum lézer alkalmazåsa forradalmi,
innovatĂv kezelĂ©si eljĂĄrĂĄs a szĂŒrkehĂĄlyog-sebĂ©szetben.
CélkitƱzés: Tanulmånyunk célja a femtoszekundum lézeres
capsulotomia sorĂĄn az elĂŒlsĆ csarnokban kĂ©pzĆdĆ szabad gyök mennyisĂ©gĂ©nek
meghatårozåsa sertésszemben. Módszer: Hetven friss sertésszemet
vontunk be a vizsgĂĄlatba, amelyeket post mortem 2 ĂłrĂĄn belĂŒl 4 ÂșC hĆmĂ©rsĂ©kleten
szĂĄllĂtottunk, a kezelĂ©st pedig 7 ĂłrĂĄn belĂŒl vĂ©geztĂŒk el. Harmincöt szemet
vizsgåltunk a kontroll- és a femtoszekundum lézeres capsulotomia csoportban is.
Luminoldependens kemilumineszcens mĂłdszer segĂtsĂ©gĂ©vel vizsgĂĄltuk a csarnokvĂz
szabadgyök-fogĂł kapacitĂĄsĂĄt, mint a szabadgyök-termelĆdĂ©s indikĂĄtorĂĄt. Az
emittĂĄlt fotonok mennyisĂ©gĂ©t relatĂv fĂ©nyegysĂ©g szĂĄzalĂ©kban fejeztĂŒk ki.
EredmĂ©nyek: A relatĂv fĂ©nyegysĂ©g szĂĄzalĂ©k alacsonyabb volt
a kontrollcsoportban (mediĂĄn 1%, interkvartilis tartomĂĄny 0,4â3%), mint a
femtoszekundum lézeres capsulotomia csoportban (mediån 4,4%, interkvartilis
tartomĂĄny 1,5â21%) (p = 0,01). KövetkeztetĂ©sek: A
femtoszekundum lĂ©zeres capsulotomia gyengĂti a csarnokvĂz antioxidĂĄns vĂ©delmĂ©t,
amely a femtoszekundum lézeres capsulotomia sorån felszabaduló szabad gyökök
hatĂĄsĂĄra utal. Orv. Hetil., 2016, 157(47), 1880â1883.
|
Abstract
Introduction: Femtosecond laser is a revolutionary, innovative
treatment method used in cataract surgery. Aim: To evaluate
free radical quantity in the anterior chamber of the eye, during femtosecond
laser assisted capsulotomy, in a porcine eye model. Method:
Seventy fresh porcine eyes were collected within 2 hours post mortem, were
transported at 4 ÂșC and treated within 7 hours. Thirty-five eyes were used as
control and 35 as femtosecond laser assisted capsulotomy group. A simple
luminol-dependent chemiluminescence method was used to measure the total
scavenger capacity in the aqueous humour, as an indicator of free radical
production. The emitted photons were expressed in relative light unit %.
Results: The relative light unit % was lower in the control
group (median 1%, interquartile range [0.4â3%]) than in the femtosecond laser
assisted capsulotomy group (median 4.4%, interquartile range [1.5%â21%]) (p =
0.01). Conclusions: Femtosecond laser assisted capsulotomy
decreases the antioxidant defense of the anterior chamber, which refers to a
significant free radical production during femtosecond laser assisted
capsulotomy. Orv. Hetil., 2016, 157(47), 1880â1883
The effect of tear supplementation with 0.15% preservative-free zinc-hyaluronate on ocular surface sensations in patients with dry eye
[Purpose]: To evaluate the effect of tear supplementation with preservative free 0.15% zinc-hyaluronate on ocular surface sensations and corneal sensitivity in dry eye patients.[Methods]: Ocular surface sensations were assessed using the ocular surface disease index (OSDI) questionnaire and by recording ocular sensations during forced blinking in parallel with noninvasive tear film breakup time measurement in 20 eyes of 20 dry eye patients. Corneal sensitivity thresholds to selective stimulation of corneal mechano-, thermal- and chemical receptors were measured using the Belmonte gas esthesiometer. All baseline measurements were repeated after 1 month of treatment with 0.15% zinc-hyaluronate.[Results]: After 1 month, a significant decrease in mean OSDI score (from 35.66 ± 12.36 to 15.03 ± 11.22; P 0.05).[Conclusion]: Prolonged use of 0.15% zinc-hyaluronate results in an improvement of tear film stability and a decrease of dry eye complaints. The decrease in corneal mechano-and polymodal receptor excitability suggests that zinc-hyaluronate helps to recover normal corneal sensitivity, and thus might have a beneficial additional effect on reducing ocular surface complaints in dry eye patients.Peer reviewe
Isotonic Glycerol and Sodium Hyaluronate Containing Artificial Tear Decreases Conjunctivochalasis after One and Three Months: A Self-Controlled, Unmasked Study.
Dry eye complaints are ranked as the most frequent symptoms of patients visiting ophthalmologists. Conjunctivochalasis is a common dry eye disorder, which can cause an unstable tear film and ocular discomfort. The severe conjunctivochalasis characterized by high LId-Parallel COnjunctival Folds (LIPCOF) degree usually requires surgical intervention, where a conservative therapy would be highly desirable. Here we examined the efficacy of a preservative-free, inorganic salt-free unit-dose artificial tear, called Conheal containing isotonic glycerol and 0.015% sodium hyaluronate in a prospective, unmasked, self-controlled study involving 20 patients. The regular use of the glycerol/hyaluronate artificial tear in three months caused a significant improvement in the recorded parameters. Conjunctivochalasis decreased from a mean LIPCOF degree of 2.9 ± 0.4 on both eyes to 1.4 ± 0.6 on the right (median decrease of -2 points, 95% CI from -2.0 to -1.0), and to 1.4 ± 0.7 on the left eye (median decrease of -1 points, 95% CI from -2.0 to -1.0) (p<0.001 for both sides). The tear film breakup time (TFBUT) lengthened from 4.8 ± 1.9 seconds on both eyes to 5.9 ± 2.3 seconds (mean increase of 1.1 seconds, 95% CI from 0.2 to 2.0) and 5.7 ± 1.8 seconds (mean increase of 0.9 seconds, 95% CI from 0.3 to 1.5) on the right and left eyes, respectively (p(right eyes) = 0.020, p(left eyes) = 0.004). The corneal lissamine staining (Oxford Scheme grade) was reduced from 1.3 ± 0.6 on the right and 1.4 ± 0.6 on the left eye significantly (p<0.001) to 0.3 ± 0.4 and 0.2 ± 0.4 on the right and the left eyes. The Ocular Surface Disease Index (OSDI) questionnaire score indicating the subjective complaints of the patients also decreased from a mean value of 36.2 ± 25.3 to 15.6 ± 16.7 (p<0.001). In this study, the artificial tear, Conheal decreased the grade of the conjunctivochalasis significantly after one month of regular use already, from the LIPCOF degree 3, considered as indication of conjunctival surgery, to a LIPCOF degree 2 or lower requiring a conservative therapy. Our results raise the possibility that vision-related quality of life can be significantly improved by conservative therapies even in severe conjunctivochalasis
Corneal Sensitivity and Dry Eye Symptoms in Patients with Keratoconus.
PURPOSE: To investigate corneal sensitivity to selective mechanical, chemical, and thermal stimulation and to evaluate their relation to dry eye symptoms in patients with keratoconus. METHODS: Corneal sensitivity to mechanical, chemical, and thermal thresholds were determined using a gas esthesiometer in 19 patients with keratoconus (KC group) and in 20 age-matched healthy subjects (control group). Tear film dynamics was assessed by Schirmer I test and by the non-invasive tear film breakup time (NI-BUT). All eyes were examined with a rotating Scheimpflug camera to assess keratoconus severity. RESULTS: KC patients had significatly decreased tear secretion and significantly higher ocular surface disease index (OSDI) scores compared to controls (5.3+/-2.2 vs. 13.2+/-2.0 mm and 26.8+/-15.8 vs. 8.1+/-2.3; p0.05). The mean threshold for selective mechanical (KC: 139.2+/-25.8 vs. control: 109.1+/-24.0 ml/min), chemical (KC: 39.4+/-3.9 vs. control: 35.2+/-1.9%CO2), heat (KC: 0.91+/-0.32 vs. control: 0.54+/-0.26 Delta degrees C) and cold (KC: 1.28+/-0.27 vs. control: 0.98+/-0.25 Delta degrees C) stimulation in the KC patients were significantly higher than in the control subjects (p0.05), whereas in the control subjects both mechanical (r = 0.52, p = 0.02), chemical (r = 0.47, p = 0.04), heat (r = 0.26, p = 0.04) and cold threshold (r = 0.40, p = 0.03) increased with age. In the KC group, neither corneal thickness nor tear flow, NI-BUT or OSDI correlated significantly with mechanical, chemical, heat or cold thresholds (p>0.05 for all variables). CONCLUSIONS: Corneal sensitivity to different types of stimuli is decreased in patients with keratoconus independently of age and disease severity. The reduction of the sensory input from corneal nerves may contribute to the onset of unpleasant sensations in these patients and might lead to the impaired tear film dynamics