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Search Results: 1 - 10 of 11305 matches for " George Kalantzis "
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Acquired color vision and visual field defects in patients with ocular hypertension and early glaucoma
Dimitris Papaconstantinou, Ilias Georgalas, George Kalantzis, Efthimios Karmiris, et al.
Clinical Ophthalmology , 2009, DOI: http://dx.doi.org/10.2147/OPTH.S5194
Abstract: cquired color vision and visual field defects in patients with ocular hypertension and early glaucoma Original Research (8735) Total Article Views Authors: Dimitris Papaconstantinou, Ilias Georgalas, George Kalantzis, Efthimios Karmiris, et al. Published Date March 2009 Volume 2009:3 Pages 251 - 257 DOI: http://dx.doi.org/10.2147/OPTH.S5194 Dimitris Papaconstantinou1, Ilias Georgalas2, George Kalantzis1, Efthimios Karmiris1, Chrysanthi Koutsandrea1, Andreas Diagourtas1, Ioannis Ladas1, Gerasimos Georgopoulos1 1Department of Ophthalmology, University of Athens, Athens, Greece; 2“G Genimatas” Hospital, NHS, Athens, Greece Purpose: To study acquired color vision and visual field defects in patients with ocular hypertension (OH) and early glaucoma. Methods: In a prospective study we evaluated 99 eyes of 56 patients with OH without visual field defects and no hereditary color deficiencies, followed up for 4 to 6 years (mean = 4.7 ± 0.6 years). Color vision defects were studied using a special computer program for Farnsworth–Munsell 100 hue test and visual field tests were performed with Humphrey analyzer using program 30–2. Both tests were repeated every six months. Results: In fifty-six eyes, glaucomatous defects were observed during the follow-up period. There was a statistically significant difference in total error score (TES) between eyes that eventually developed glaucoma (157.89 ± 31.79) and OH eyes (75.51 ± 31.57) at the first examination (t value 12.816, p < 0.001). At the same time visual field indices were within normal limits in both groups. In the glaucomatous eyes the earliest statistical significant change in TES was identified at the first year of follow-up and was –20.62 ± 2.75 (t value 9.08, p < 0.001) while in OH eyes was 2.11 ± 4.36 (t value 1.1, p = 0.276). Pearson’s coefficient was high in all examinations and showed a direct correlation between TES and mean deviation and corrected pattern standard deviation in both groups. Conclusion: Quantitative analysis of color vision defects provides the possibility of follow-up and can prove a useful means for detecting early glaucomatous changes in patients with normal visual fields.
Nd: YAG capsulotomy for posterior capsule opacification after combined clear corneal phacoemulsification and vitrectomy
Ilias Georgalas,Petros Petrou,George Kalantzis,Dimitrios Papaconstantinou
Therapeutics and Clinical Risk Management , 2009,
Abstract: Ilias Georgalas1, Petros Petrou2, George Kalantzis2, Dimitrios Papaconstantinou2, Chrysanthi Koutsandrea2, Ioannis Ladas21Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, NHS, Athens, Greece; 2Department of Ophthalmology, University of Athens, Athens, GreecePurpose: To evaluate the efficacy and safety of Neodymium:YAG (Nd:YAG) laser capsulotomy for posterior capsule opacification (PCO) following combined phacoemulsification and vitrectomy for the treatment of cataract in association with macular hole (MH) or epiretinal membrane (ERM).Methods: Retrospective clinical study of 34 eyes of 34 patients who underwent combined cataract surgery and vitrectomy, developed PCO, and subsequently underwent Nd:YAG laser capsulotomy. Follow-up examinations included visual acuity measurement, evaluation of intraocular lens (IOL) centration, intraocular pressure (IOP) measurement, and dilated fundus examination.Results: Nd:YAG laser capsulotomy was performed in all 34 eyes. The mean age of the patients was 65.08 years (range 45–87) and the mean follow up period was 11.05 months (range 4–23). The mean time elapsed between the last intraocular operation and the development of PCO was 10.00 months for patients with previous ERM and 15.33 for those with MH (P = 0.001, t-test for equality of means). None of our patients developed recurrence of MH, retinal detachment, IOL dislocation, or permanent IOP elevation.Conclusion: In our study, the most remarkable observation is that no complication occurred after the YAG capsulotomy, possibly because the eyes were vitrectomized and vitreous seems to play an important role in the occurrence of post-Nd:YAG complications. In addition we noted that PCO seems to occur earlier in the eyes undergoing combined surgery for cataract and ERM when compared with those where combined phacoemulsification and vitrectomy are performed for cataract and MH.Keywords: Nd:YAG capsulotomy, phacoemulsification, vitrectomy
Angioid streaks, clinical course, complications, and current therapeutic management
Ilias Georgalas,Dimitris Papaconstantinou,Chrysanthi Koutsandrea,George Kalantzis
Therapeutics and Clinical Risk Management , 2008,
Abstract: Ilias Georgalas1, Dimitris Papaconstantinou2, Chrysanthi Koutsandrea2, George Kalantzis2, Dimitris Karagiannis2, Gerasimos Georgopoulos2, Ioannis Ladas21Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, NHS, Athens, Greece; 2Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, University of Athens, Athens, GreeceAbstract: Angioid streaks are visible irregular crack-like dehiscences in Bruch’s membrane that are associated with atrophic degeneration of the overlying retinal pigmented epithelium. Angioid streaks may be associated with pseudoxanthoma elasticum, Paget’s disease, sickle-cell anemia, acromegaly, Ehlers–Danlos syndrome, and diabetes mellitus, but also appear in patients without any systemic disease. Patients with angioid streaks are generally asymptomatic, unless the lesions extend towards the foveola or develop complications such as traumatic Bruch’s membrane rupture or macular choroidal neovascularization (CNV). The visual prognosis in patients with CNV secondary to angioid streaks if untreated, is poor and most treatment modalities, until recently, have failed to limit the devastating impact of CNV in central vision. However, it is likely that treatment with antivascular endothelial growth factor, especially in treatment-naive eyes to yield favorable results in the future and this has to be investigated in future studies.Keywords: angioid streaks, pseudoxanthoma elasticum, choroidal neovascularization
Acquired color vision and visual field defects in patients with ocular hypertension and early glaucoma
Dimitris Papaconstantinou,Ilias Georgalas,George Kalantzis,Efthimios Karmiris
Clinical Ophthalmology , 2009,
Abstract: Dimitris Papaconstantinou1, Ilias Georgalas2, George Kalantzis1, Efthimios Karmiris1, Chrysanthi Koutsandrea1, Andreas Diagourtas1, Ioannis Ladas1, Gerasimos Georgopoulos11Department of Ophthalmology, University of Athens, Athens, Greece; 2“G Genimatas” Hospital, NHS, Athens, GreecePurpose: To study acquired color vision and visual field defects in patients with ocular hypertension (OH) and early glaucoma.Methods: In a prospective study we evaluated 99 eyes of 56 patients with OH without visual field defects and no hereditary color deficiencies, followed up for 4 to 6 years (mean = 4.7 ± 0.6 years). Color vision defects were studied using a special computer program for Farnsworth–Munsell 100 hue test and visual field tests were performed with Humphrey analyzer using program 30–2. Both tests were repeated every six months. Results: In fifty-six eyes, glaucomatous defects were observed during the follow-up period. There was a statistically significant difference in total error score (TES) between eyes that eventually developed glaucoma (157.89 ± 31.79) and OH eyes (75.51 ± 31.57) at the first examination (t value 12.816, p < 0.001). At the same time visual field indices were within normal limits in both groups. In the glaucomatous eyes the earliest statistical significant change in TES was identified at the first year of follow-up and was –20.62 ± 2.75 (t value 9.08, p < 0.001) while in OH eyes was 2.11 ± 4.36 (t value 1.1, p = 0.276). Pearson’s coefficient was high in all examinations and showed a direct correlation between TES and mean deviation and corrected pattern standard deviation in both groups.Conclusion: Quantitative analysis of color vision defects provides the possibility of follow-up and can prove a useful means for detecting early glaucomatous changes in patients with normal visual fields.Keywords: color vision defects, glaucoma, hereditary, vision field
Excision margins in squamous cell carcinoma of the tongue: A retrospective audit and review of the literature  [PDF]
Miriam Thake, Athanasis Kalantzis
Open Journal of Stomatology (OJST) , 2013, DOI: 10.4236/ojst.2013.31013
Abstract:

The incidence of close and involved tongue resection margins for squamous cell carcinoma (SCC) were reviewed with the aim to identify any possible need for change in the surgical approach to glossectomies. The histopathological reports of 101 partial glossectomies for SCC between 2006 and 2012 were retrospectively reviewed. Results: Overall 52 (51.5%) patients had one or more close or involved margin and 9 (8.9%) had both close and involved margins. 42 (41.5%) patients had close margins and 11 (10.9%) had involved margins. The inferior/lateral muscoal margin was most frequently close/involved (32%) followed by deep margin (27%). The anterior margin was least close/involved (5%). The posterior and superior/medical margins were close/involved in 12% and 11% of cases respectively. Conclusions: 52.5% of patients had close or involved margins following surgery, potentially requiring further treatment to avoid an increased risk of tumour recurrence and the associated increase in morbidity and mortality. The inferior/lateral and deep margins were most frequently involved possible due to the anatomical difficulties visualising and dissecting these margins. The potential explanations for these disparities and possible solutions are discussed.

Nd: YAG capsulotomy for posterior capsule opacification after combined clear corneal phacoemulsification and vitrectomy
Ilias Georgalas, Petros Petrou, George Kalantzis, Dimitrios Papaconstantinou, Chrysanthi Koutsandrea, Ioannis Ladas
Therapeutics and Clinical Risk Management , 2009, DOI: http://dx.doi.org/10.2147/TCRM.S4754
Abstract: : YAG capsulotomy for posterior capsule opacification after combined clear corneal phacoemulsification and vitrectomy Original Research (5712) Total Article Views Authors: Ilias Georgalas, Petros Petrou, George Kalantzis, Dimitrios Papaconstantinou, Chrysanthi Koutsandrea, Ioannis Ladas Published Date January 2009 Volume 2009:5 Pages 133 - 137 DOI: http://dx.doi.org/10.2147/TCRM.S4754 Ilias Georgalas1, Petros Petrou2, George Kalantzis2, Dimitrios Papaconstantinou2, Chrysanthi Koutsandrea2, Ioannis Ladas2 1Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, NHS, Athens, Greece; 2Department of Ophthalmology, University of Athens, Athens, Greece Purpose: To evaluate the efficacy and safety of Neodymium:YAG (Nd:YAG) laser capsulotomy for posterior capsule opacification (PCO) following combined phacoemulsification and vitrectomy for the treatment of cataract in association with macular hole (MH) or epiretinal membrane (ERM). Methods: Retrospective clinical study of 34 eyes of 34 patients who underwent combined cataract surgery and vitrectomy, developed PCO, and subsequently underwent Nd:YAG laser capsulotomy. Follow-up examinations included visual acuity measurement, evaluation of intraocular lens (IOL) centration, intraocular pressure (IOP) measurement, and dilated fundus examination. Results: Nd:YAG laser capsulotomy was performed in all 34 eyes. The mean age of the patients was 65.08 years (range 45–87) and the mean follow up period was 11.05 months (range 4–23). The mean time elapsed between the last intraocular operation and the development of PCO was 10.00 months for patients with previous ERM and 15.33 for those with MH (P = 0.001, t-test for equality of means). None of our patients developed recurrence of MH, retinal detachment, IOL dislocation, or permanent IOP elevation. Conclusion: In our study, the most remarkable observation is that no complication occurred after the YAG capsulotomy, possibly because the eyes were vitrectomized and vitreous seems to play an important role in the occurrence of post-Nd:YAG complications. In addition we noted that PCO seems to occur earlier in the eyes undergoing combined surgery for cataract and ERM when compared with those where combined phacoemulsification and vitrectomy are performed for cataract and MH.
Angioid streaks, clinical course, complications, and current therapeutic management
Ilias Georgalas, Dimitris Papaconstantinou, Chrysanthi Koutsandrea, George Kalantzis, Dimitris Karagiannis, et al
Therapeutics and Clinical Risk Management , 2009, DOI: http://dx.doi.org/10.2147/TCRM.S4682
Abstract: ngioid streaks, clinical course, complications, and current therapeutic management Review (7828) Total Article Views Authors: Ilias Georgalas, Dimitris Papaconstantinou, Chrysanthi Koutsandrea, George Kalantzis, Dimitris Karagiannis, et al Published Date December 2008 Volume 2009:5 Pages 81 - 89 DOI: http://dx.doi.org/10.2147/TCRM.S4682 Ilias Georgalas1, Dimitris Papaconstantinou2, Chrysanthi Koutsandrea2, George Kalantzis2, Dimitris Karagiannis2, Gerasimos Georgopoulos2, Ioannis Ladas2 1Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, NHS, Athens, Greece; 2Department of Ophthalmology, “G. Gennimatas” Hospital of Athens, University of Athens, Athens, Greece Abstract: Angioid streaks are visible irregular crack-like dehiscences in Bruch’s membrane that are associated with atrophic degeneration of the overlying retinal pigmented epithelium. Angioid streaks may be associated with pseudoxanthoma elasticum, Paget’s disease, sickle-cell anemia, acromegaly, Ehlers–Danlos syndrome, and diabetes mellitus, but also appear in patients without any systemic disease. Patients with angioid streaks are generally asymptomatic, unless the lesions extend towards the foveola or develop complications such as traumatic Bruch’s membrane rupture or macular choroidal neovascularization (CNV). The visual prognosis in patients with CNV secondary to angioid streaks if untreated, is poor and most treatment modalities, until recently, have failed to limit the devastating impact of CNV in central vision. However, it is likely that treatment with antivascular endothelial growth factor, especially in treatment-naive eyes to yield favorable results in the future and this has to be investigated in future studies.
Imaging capsule: Does it represent a real progress?
N. Kalantzis,P. Apostolopoulos
Annals of Gastroenterology , 2007,
Abstract:
The Role of the Internet in Changing Knowledge Ecologies
Cope, Bill,Kalantzis, Mary
Arbor : Ciencia, Pensamiento y Cultura , 2009, DOI: 10.3989/arbor.2009.i737.309
Abstract: To a greater extent than is often acknowledged, the modern scientific and university-based knowledge system is a creature of the society of the printing press. Until the turn of the twentyfirst century, print was the medium of scholarly communication. Then, quite suddenly at the turn of the twenty-first century, digital text begins to displace print as the primary means of access to the knowledge of academicians. This article explores some of the consequences of this change. To what extent do digital technologies of representation and communication reproduce the knowledge systems of the half-millennium long history of the modern university or do they disrupt and transform them? To answer this question, this article will explore key aspects of contemporary transformations, not just in the textual forms of digital representation, but the emerging social forms that digitisation reflects, affords and supports. This we call the “social web”, a term we use to describe the kinds of relationships to knowledge and culture that are emerging in the era of pervasively interconnected computing. What, then, are the impacts and potentials of these changes on the processes of formation of new knowledge? Más allá de lo que suele admitirse, el moderno sistema de conocimiento científico y universitario es una creación de la sociedad de la imprenta. Antes de llegar el siglo XXI, la imprenta era el canal de comunicación académica. Entonces, de manera bastante repentina con el cambio de siglo, los textos digitales empezaron a sustituir a la imprenta como el medio principal por el que los académicos acceden al conocimiento. Este artículo analiza algunas de las consecuencias de este cambio. Hasta qué punto las tecnologías digitales de representación y comunicación reproducen los sistemas de conocimiento utilizados en el último medio milenio de historia de la moderna universidad? O quizás la interrumpen y la transforman? Para responder a esta pregunta, este artículo explora aspectos clave de las transformaciones contemporáneas, no sólo en la forma textual de las representaciones digitales, sino también la emergencia de formas sociales que la digitalización refleja, permite y apoya. A esto llamamos la “web social”, una expresión que utilizamos para describir el tipo de relaciones con el conocimiento y la cultura que está emergiendo en esta era dominada por la interconexión computacional. Cuáles son entonces los impactos y el potencial de estos cambios sobre los procesos de formación de nuevo conocimiento?
Structural Plasticity Can Produce Metaplasticity
Georgios Kalantzis,Harel Z. Shouval
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008062
Abstract: Synaptic plasticity underlies many aspect of learning memory and development. The properties of synaptic plasticity can change as a function of previous plasticity and previous activation of synapses, a phenomenon called metaplasticity. Synaptic plasticity not only changes the functional connectivity between neurons but in some cases produces a structural change in synaptic spines; a change thought to form a basis for this observed plasticity. Here we examine to what extent structural plasticity of spines can be a cause for metaplasticity. This study is motivated by the observation that structural changes in spines are likely to affect the calcium dynamics in spines. Since calcium dynamics determine the sign and magnitude of synaptic plasticity, it is likely that structural plasticity will alter the properties of synaptic plasticity.
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