Publications by authors named "Ahmed Hassanein"

29 Publications

  • Page 1 of 1

Mechanics of guided growth of the distal femur for correction of fixed knee flexion deformities: an extra-articular technique.

Arch Orthop Trauma Surg 2021 Apr 21. Epub 2021 Apr 21.

Department of Orthopaedic and Trauma Surgery, Assiut University Hospitals, Assiut, Egypt.

Introduction: Anterior distal femoral hemiepiphysiodesis using intra-articular plates for correction of pediatric fixed knee flexion deformities (FKFD) has two documented complications: postoperative knee pain and implant loosening. The aim of this study is to investigate the mechanical properties of a novel extra-articular technique for anterior distal femoral hemiepiphysiodesis in patients with FKFD and to compare them to the conventional technique.

Materials And Methods: Sixteen femoral sawbones were osteotomized at the level of the distal femoral physis and fixed by rail frames to allow linear distraction simulating longitudinal growth. Each sawbone was tested twice: first using the conventional technique with eight plates placed anteriorly just medial and lateral to the femoral sulcus (group A) and then with plates inserted in the proposed novel location at the most anterior part of the medial and lateral surfaces of the femoral condyles with screws in the coronal plane (group B). Gradual linear distraction was performed, and the resulting angular correction was measured. Strain gauges were attached to the plates, and the amount of strain (and equivalent stress) over the plates in response to linear distraction was recorded. The two groups were compared using the Wilcoxon signed-rank test.

Results: The amount of angular correction was statistically higher in group B (extra-articular plates) at 5, 10-, and 15-mm of distraction (p < 0.001). As regards stress over the plates, the maximum stress and the area under the curve (sum of all stresses measured throughout the distraction process) were significantly higher when the plates were inserted at the conventional position (group A) (p < 0.001).

Conclusions: During anterior distal femoral hemiepiphysiodesis, the fixation of the eight plates in the coronal plane at the anterior part of the femoral condyles may produce a greater amount of correction and a lower degree of stress over the implants as compared to the conventional technique.
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http://dx.doi.org/10.1007/s00402-021-03911-2DOI Listing
April 2021

In vivo anti-inflammatory and hepatoprotective activities of (Forssk.) aerial parts in relation to its phytomolecules.

Nat Prod Res 2020 Nov 16:1-6. Epub 2020 Nov 16.

Department of Pharmacognosy, Faculty of Pharmacy, Al-Azhar University, Assiut-Branch, Assiut, Egypt.

A total methanolic extract and its sub-extracts of (Forssk.) aerial parts were subjected to acute toxicity, anti-inflammatory, and hepatoprotective investigations. The methanolic extract was safe upto 3 g/kg on mice. The EtOAc fraction reduced the carrageenan-induced rat paw edema better than indomethacin. It also demonstrated a drop in the elevated ALT, AST, and TB at 300 mg/kg, better than silymarin. Histopathological examination of liver cells of rats given the EtOAc fraction showed a complete absence of the CCl-induced cloudy swelling. A phytochemical investigation of the -hexane and EtOAc fractions yielded 11 compounds [indole-3-carboxylic acid (), -butyl palmitate (), tyrosol (), L-rhamnonic acid-1,4-lactone (), -sitosterol/stigmasterol mixture (), -sitosterol/stigmasterol glycosides mixture ('), chrysoeriol (), luteolin (), apigenin (), crenatoside (), and verbascoside ()] as identified by UV, 1D & 2D NMR and ESIMS techniques. Their reported biological actions were in relation to and supported our herein detected pharmacological findings.
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http://dx.doi.org/10.1080/14786419.2020.1845167DOI Listing
November 2020

Assessment of the Outcome of Calvarial Vault Remodeling and Spring-Mediated Cranioplasty in the Correction of Isolated Sagittal Suture Synostosis.

J Craniofac Surg 2020 Oct;31(7):e747-e752

Neurosurgery Department, Faculty of Medicine, Sohag University, Sohag, Egypt.

Background: Sagittal synostosis is the commonest form of nonsyndromic isolated craniosynostosis. Calvarial vault remodeling (CVR) and spring-mediated cranioplasty (SMC) are the commonly used correction techniques.

Aim Of The Work: To study and compare clinical and radiographic outcomes of CVR and SMC in the correction of isolated sagittal suture synostosis.

Methods: A prospective cohort with the patients were divided into group; I (SMC) and II (CVR), each 15 patients. They were observed to evaluate the outcome and detect complications.

Results: Mean operative time was 59.2 minutes in SMC and 184 minutes in CVR. Mean intraoperative blood loss was 26 mL in SMC and 64.7 mL in CVR. Intraoperative complications in SMC were dural tear in 1 patient and superior sagittal sinus injury in another patient, while in CVR 2 patients with dural tears and a 3rd with superior sagittal sinus injury. Postoperative complications in SMC were exposed spring, gaped wound, and parietal eminence elevation, while in CVR 2 patients needed blood transfusion. The mean hospital stays was 1.4 days in SMC and 4.1 days in CVR. In SMC, the relative increase in cephalic index varied between 5.5% and 8.2%, while for CVR, it varied between 5.1% and 7.9%.

Conclusion: The SMC and CVR are safe procedures, with good long-term results and significant objective changes toward normalization of the skull morphology in isolated sagittal craniosynostosis. The SMC is less invasive and associated with reduced hospital stays, decreased blood loss, and can be performed at a younger age than CVR with a lower morbidity.
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http://dx.doi.org/10.1097/SCS.0000000000006807DOI Listing
October 2020

Do perioperative protocols of enhanced recovery after cardiac surgery improve postoperative outcome?

Interact Cardiovasc Thorac Surg 2020 05;30(5):706-710

Department of Anaesthesia and intensive care, Minia University, El-Minya, Egypt.

A best evidence topic was constructed according to a structured protocol. The question addressed was whether the application of an enhanced recovery protocol or pathway improves patient outcomes after cardiac surgery. A total of 3091 papers were found using the reported search. Finally, 12 papers represented the best available evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Six studies referred to enhanced recovery protocol as fast track (FT) and another 6 studies referred to it as enhanced recovery after surgery (ERAS). Significant differences from conventional care were reported for time to extubation or intubation time in 4 studies (3 FT, 1 ERAS), duration of intensive care unit stay in 6 studies (4 FT, 2 ERAS), length of hospital stay (LOS) in 8 studies (5 FT, 3 ERAS), cost in 5 studies (4 FT, 1 ERAS), pain scores in 2 studies (2 ERAS) and opioid use in 3 studies (3 ERAS). We conclude that FT or ERAS improve postoperative outcomes including length of stay and pain control, without increasing morbidity, mortality or readmission. However, there is a need for prospective studies and standardized protocols.
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http://dx.doi.org/10.1093/icvts/ivaa001DOI Listing
May 2020

trachylobane-3-hydroperoxide, a new diterpene from the root bark of (Fam.; Euphorbiaceae).

Nat Prod Res 2019 Nov 6:1-8. Epub 2019 Nov 6.

Faculty of Pharmacy, Department of Pharmacognosy, Helwan University, Cairo, Egypt.

New trachylobane-3-hydroperoxide together with four known compounds, ricinine , trimethoxy ellagic acid , dimethoxy ellagic acid and aleurotolic acid were isolated from the methylene chloride fraction of the root bark of . The structures of these secondary metabolites were elucidated by using different spectroscopic techniques, H NMR, C NMR, HSQC, HMBC, H-H COSY, NOESY, HR-ESI-MS, EI-MS and comparison with published data. trachylobane-3-hydroperoxide showed moderate cytotoxic activity by MTT assay method against human breast cancer cells (MCF-7) and human hepatocyte-derived carcinoma cells (Huh-7) with IC values of 24.53 and 34.13 µM, in comparison with IC values of 23.47 µM and 15.82 µM for 5-fluorouracil respectively.
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http://dx.doi.org/10.1080/14786419.2019.1687477DOI Listing
November 2019

The Outcome of Multidisciplinary Management of Carotid Body Tumors: Retrospective Cohort Study.

J Maxillofac Oral Surg 2019 Dec 3;18(4):610-616. Epub 2018 Dec 3.

4Radiology Department, Faculty of Medicine, Al-Baha University, Al-Baha, Kingdom of Saudi Arabia.

Background: Carotid body tumor (CBT) is a rare paraganglionic hyper-vascular tumor of the carotid body. The standard treatment for CBTs is surgery, but it involves risk. The study is aimed to assess the CBTs and evaluate the outcome of multidisciplinary management.

Materials And Methods: A retrospective cohort study included patients with CBTs who were managed by surgical excision between May 2006 and April 2018. A multidisciplinary team was established to excise the tumor completely with minimal neurovascular compromise.

Results: The study comprised of 32 patients in the age group of 23-65 years. The main presentation was a unilateral painless neck mass. Six cases (18.75%) were Shamblin I, 10 (31.25%) Shamblin II and 16 (50%) Shamblin III. Complete excision was performed for all cases. Ligation of the external carotid artery was done in 15 cases (46.88%) and repair of the internal carotid artery in 6 (18.75%). Postoperative cranial nerve complications occurred in six patients (18.75%): four transient hypoglossal pareses and two hoarseness of voice. Histopathologically, one case (3.125%) was malignant. No recurrence was detected through the follow-up period.

Conclusion: A multidisciplinary approach is essential for management of CBTs. Early diagnosis and surgical resection minimize morbidity and carry good surgical outcome.

Trial Registration Number: ChiCTR1800018722 (: Chinese Clinical Trial Registry).
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http://dx.doi.org/10.1007/s12663-018-1176-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6795643PMC
December 2019

Controversy on the Age of Hypertelorism Correction.

J Craniofac Surg 2019 Sep;30(6):1859-1865

Neurosurgery Department, Faculty of Medicine, Sohag University, Sohag, Egypt.

Introduction: Orbital hypertelorism (HTO) is a challenging craniofacial problem seen in association with some congenital deformities. The age of HTO correction is a matter of debate.

The Aim Of The Work: to evaluate the outcome of HTO correction and determine the optimal timing for intervention, striving for the earliest possible intervention with the lowest relapse.

Patients And Methods: A standard craniofacial approach with medial bone resection, 4 walls orbital box osteotomy and orbital medialization were done for all patients. Skeletal and soft tissue procedures were done as indicated.

Results: there were 10 patients aging 6 to 19 years. Seven were associated with craniofacial clefts, and 3 with craniosynostosis syndromes. HTO was severe in 8 cases and moderate in 2 cases. It was asymmetric in 2 cases. Frontoorbital remodeling was done in 3 cases with craniosynostosis. Failed surgery was reported in 2 cases. A redo surgery was done for one of them with an excellent outcome, while refused by the other. Nine patients had an excellent outcome. The mean level of satisfaction was 93.37%. Three patients had ugly facial scars. No major complications were recorded.

Conclusion: The time for surgical treatment of HTO is determined by the severity of the associated deformity. If there is an urgent factor indicating intervention, early correction can be performed exceptionally; otherwise, HTO correction should be performed after the age of 6 years.
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http://dx.doi.org/10.1097/SCS.0000000000005625DOI Listing
September 2019

Trends and Outcomes of Management of Mandibular Fractures.

J Craniofac Surg 2019 Jun;30(4):1245-1251

Maxillofacial Surgery Unit, General Surgery Department, Sohag Faculty of Medicine, Sohag University, Sohag, Egypt.

Introduction: the diversity of the causes of trauma produces different patterns of fractures depending on sociodemographics, lifestyle, industry, and outdoor activities. Mandibular fractures (MFs) are the commonest facial fractures. Reconstruction aims to restore the preinjury anatomy and function as much as possible.

Aim Of The Study: to evaluate the demographics, etiologies, patterns, treatment modalities and outcomes of management of MFs in southern Egypt.

Patients And Methods: records of 1371 patients with MFs were reviewed to study the incidence, causes, patterns, treatment modalities and outcomes of surgical management.

Results: the study included 1152 (84.03%) males and 219 (15.97%) females. The second and third decades were the most vulnerable groups. Isolated MFs appeared in 75.49% of patients while in the others either zygoma and/or maxilla were affected. The commonest causes were road traffic accidents (66.89%) and fall from height (15.1%). The body was the commonest involved region (30.98%), followed by parasymphyseal region (24.33%). In 66.16% of patients, the treatment was open reduction and internal fixation while in 22.17%, closed reduction and intermaxillary fixation were used. 20.24% of the cases had 1 or more postoperative complications, mainly temporomandibular joint dysfunction in 64 cases, malocclusion in 58 cases, and paresthesia in 42 cases.

Conclusion: the MFs are common in the youth. The road traffic accidents are the most common etiology. This can be reduced by simple measures like compulsory seat belts and wearing the helmet. Open reduction and internal fixation is the commonest treatment modality.
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http://dx.doi.org/10.1097/SCS.0000000000005469DOI Listing
June 2019

Continuous Validity of Temporalis Muscle Flap in Reconstruction of Postablative Palatomaxillary Defects.

J Craniofac Surg 2017 Mar;28(2):e130-e137

Maxillofacial Surgery Unit, Faculty of Medicine, Sohag University, Sohag, Egypt.

Introduction: Postablative palatomaxillary defects (PAPMDs) represent a challenging reconstructive problem. Temporalis muscle flap (TMF) has been widely used for reconstruction of these defects with minimal morbidity and satisfactory outcome.

Aim Of The Study: To presents the authors' experience in the reconstruction of PAPMDs with TMF and to evaluate the validity of TMF in the reconstruction of such defects.

Methods: This prospective study was conducted between July 2011 and July 2016 on selected patients for primary reconstruction of PAPMDs with TMF. Temporalis muscle flaps were assessed during surgery and postoperatively. Patients were followed up to evaluate functional and esthetic outcomes and detect complications.

Results: This study included 32 patients with mean age 48.3 years. The pathology was squamous cell carcinoma in 15 patients (46.9%). Twenty-one patients (65.6%) had type II maxillectomy. Mean time of flap harvesting was 43 minutes. Zygomatic arch osteotomy was done in 3 patients while Coronoid osteotomy in 4 patients. Postoperatively, flaps were viable in 31 patients (96.9%) with good healing of recipient site. Flap epithelization completed within 28 to 59 days. Follow-up period was 13 to 55 months. Satisfactory functional and esthetic outcomes were reported in most of patients with no recurrence. Transient temporal nerve palsy occurred in 2 patients, limited mouth opening in 5 patients. One patient had Transient diplopia with enopthalmos and hypophthalmos. Flap failure occurred in another patient.

Conclusions: Temporalis muscle flap is still a valid reliable and versatile reconstructive tool in palatomaxillary reconstruction after ablative surgery. It has a good cosmetic and functional outcomes and minimal morbidity.
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http://dx.doi.org/10.1097/SCS.0000000000003323DOI Listing
March 2017

Orbitocranial Fibrous Dysplasia: Outcome of Radical Resection and Immediate Reconstruction With Titanium Mesh and Pericranial Flap.

J Craniofac Surg 2016 Nov;27(8):e719-e723

*Neurosurgery Department†Maxillofacial Surgery Unit, Faculty of Medicine, Sohag University, Sohag, Egypt.

Introduction: Fibrous dysplasia (FD) is a non-neoplastic developmental fibro-osseous disease. It represents 2.5% of all bone tumors and 5% to 7% of the benign bone tumors. Orbitocranial region is involved in about 20% of the patients. The main presentations are craniofacial deformity and headache. Loss of vision is the most devastating result of this disease. There is no medical treatment to cure or prevent FD. Radiation therapy is contraindicated. Surgery for the orbitocranial FD is often challenging because of the proximity of neurovascular and ocular structures. Conservative surgical shaving and recontouring is always associated with suboptimal results. Radical excision is potentially curative with no extra morbidity. Orbital hypertelorism, dystopia, or proptosis can be corrected only by radical excision and reconstruction.

Aim: The aim of the study was to evaluate the outcome of radical excision of the orbitocranial FD and immediate reconstruction using titanium mesh and pericranial flap.

Patients And Methods: This prospective study had been conducted on 22 patients with orbitocranial FD with age range from 17 to 52 years (mean 29.5). Radical excision of the lesions was done for all patients through transcranial approach. Immediate reconstruction was achieved using titanium mesh and pericranial flap.

Results: Intraoperative dural tears and cerebrospinal fluid leak were reported in 2 patients and repaired with galeal graft. Supraorbital anesthesia occurred in 6 patients. Of these, 2 patients were transient, while the remaining 4 patients were permanent. Wound infection was noticed in 1 patient who improved by medical treatment. Temporary postoperative diplopia occurred in 1 patient and temporary postoperative impaired vision in 1 other patient. In all patients, acceptable or good aesthetic results were observed. No recurrence was detected in our series during the follow-up period that ranged from 24 to 58 months (mean 37.5 months).

Conclusion: Radical excision of orbitocranial FD is potentially curative with no extra morbidity. It can achieve good aesthetic and functional results with no recurrence.
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http://dx.doi.org/10.1097/SCS.0000000000003033DOI Listing
November 2016

NbO Nanostructure Evolution on Nb Surfaces via Low-Energy He Ion Irradiation.

ACS Appl Mater Interfaces 2016 Dec 7;8(50):34896-34903. Epub 2016 Dec 7.

Center for Materials Under eXtreme Environment (CMUXE), School of Nuclear Engineering, Purdue University , West Lafayette, Indiana 47907, United States.

We propose low-energy, broad-beam He ion irradiation as a novel processing technique for the generation of NbO surface nanostructures due to its relative simplicity and scalability in a commercial setting. Since there have been relatively few studies involving the interaction of high-fluence, low-energy He ion irradiation and Nb (or its oxidized states), this systematic study explores both effects of fluence and sample temperature during irradiation on resulting surface morphology. Detailed normal and cross-sectional scanning electron microscopy (SEM) studies reveal subsurface He bubble formation and elucidate potential driving mechanisms for nanostructure evolution. A combination of specular optical reflectivity and X-ray photoelectron spectroscopy (XPS) is also used to gain additional information on roughness and stoichiometry of irradiated surfaces. Our investigations show significant surface modification for all tested irradiation conditions; the resulting surface structure size and geometry have a strong dependence on both sample temperature during irradiation and total ion fluence. Optical reflectivity measurements on irradiated surfaces demonstrate increased surface roughening with increasing ion fluence, and XPS shows higher oxidation levels for samples irradiated at lower temperatures, suggesting larger surface roughness and porosity. Overall, it was found that low-energy He ion irradiation is an efficient processing technique for nanostructure formation, and surface structures are highly tunable by adjusting ion fluence and NbO sample temperature during irradiation. These findings may have excellent potential applications for solar energy conversion through improved efficiency due to effective light absorption.
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http://dx.doi.org/10.1021/acsami.6b12502DOI Listing
December 2016

Characteristics of Ions Emission from Ultrashort Laser Produced Plasma.

Sci Rep 2016 12 1;6:38256. Epub 2016 Dec 1.

Center for Materials under Extreme Environment (CMUXE), School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA.

The dynamic characteristics of the ions emitted from ultrashort laser interaction with materials were studied. A series of successive experiments were conducted for six different elements (C, Al, Cu, Mo, Gd, and W) using 40 fs, 800 nm Ti: Sapphire laser. Time-of-flight (TOF) ion profile was analyzed and charge emission dependencies were investigated. The effects of incident laser interaction with each element were studied over a wide range of laser fluences (0.8 J/cm to 24 J/cm) corresponding to laser intensities (2.0 × 10 W/cm to 6.0 × 10 W/cm). The dependencies of the angular resolved ion flux and energy were also investigated. The TOF ion profile exhibits two peaks corresponding to a fast and a slow ion regime. The slow ions emission was the result of thermal vaporization while fast ions emission was due to time dependent ambipolar electric field. A theoretical model is proposed to predict the total ion flux emitted during femtosecond laser interaction that depends on laser parameters, material properties, and plume hydrodynamics. Incident laser fluence directly impacts average charge state and in turn affects the ion flux. Slow ions velocity exhibited different behavior from fast ions velocity. The fast ions energy and flux were found to be more collimated.
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http://dx.doi.org/10.1038/srep38256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5131299PMC
December 2016

Can Submandibular Tracheal Intubation Be an Alternative to Tracheotomy During Surgery for Major Maxillofacial Fractures?

J Oral Maxillofac Surg 2017 Mar 2;75(3):508.e1-508.e7. Epub 2016 Nov 2.

Lecturer of Anesthesia, Anesthesia Department, Faculty of Medicine, Sohag University, Sohag, Egypt.

Purpose: During surgery for major maxillofacial fractures, orotracheal intubation can interfere with some surgical procedures and nasal intubation can be contraindicated or impossible. That is why tracheotomy is presented as a solution, although it carries a relatively high incidence of complications. In this study, the use of submandibular tracheal intubation is basically evaluated as an alternative to tracheotomy in such circumstances.

Materials And Methods: This prospective study was performed in patients undergoing surgery for major maxillofacial fractures in which oral intubation and/or nasal intubation have been unsuitable, impossible, or contraindicated. The technique of submandibular intubation was assessed intraoperatively and in the postoperative period. The outcomes and complications are presented.

Results: The study included 26 patients aged between 14 and 57 years. All patients had mandibular fractures, with 19 midface fractures (73.1%), 11 nasal bone fractures (42.3%), 10 zygomatic bone fractures (38.5%), 9 naso-orbito-ethmoidal fractures (34.6%), and 9 frontobasilar fractures (34.6%). The procedure time ranged from 5 to 12 minutes (mean, 7 minutes 4.6 seconds). Delayed extubation was performed in 15 cases (57.7%) in which the tube was left in place for a period ranging from 8 to 50 hours (mean, 30 hours 24 minutes). The technique has proved to be straightforward and satisfactory. A postoperative superficial infection occurred in 2 patients, whereas hypertrophic scars occurred in another 2 patients.

Conclusions: Submandibular endotracheal intubation is straightforward, safe, and quick to carry out. It can be an alternative to tracheotomy as it allows operative techniques and postoperative airway protection without the risks and side effects of tracheotomy.
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http://dx.doi.org/10.1016/j.joms.2016.10.030DOI Listing
March 2017

Single-Stage Combined Craniofacial Repair for Frontoethmoidal Meningoencephalocele.

J Craniofac Surg 2017 Jan;28(1):e9-e12

*Maxillofacial Surgery Unit †Neurosurgery Department, Faculty of Medicine, Sohag University, Sohag, Egypt.

Introduction: Frontoethmoidal meningoencephalocele (FMEC) is a rare congenital anomaly characterized by herniation of brain tissue and meninges through a defect in the cranium and associated with facial dysmorphism. Treatment modalities include extra cranial, transcranial, or combined craniofacial approaches. The combined approach is considered the best treatment choice.

Methods: Twelve patients with FMEC aging from 6 months to 4 years were treated by single-stage combined craniofacial approach between July 2011 and July 2015. They were followed up for evaluation of outcome and detection of complications.

Results: Seven patients (58.3%) were males and 5 patients (41.7%) were females. Eight patients (66.7%) were less than 2 years while 4 patients (33.3%) were between 2 and 4 years. The main presentations were external mass, telecanthus and hypertelorbitism, radiologically, frontobasal bone defect and herniated dural sac with brain tissue were detected in all patients. Excision of the mass with dural repair, craniofacial reconstruction, and medial canthopexy were done for all patients. Orbital translocation was done for 8 patients (75%), nasal reconstruction for 7 patients (58.3%), while dacryocystorhinostomy in 3 patients (25%). Venticuloperitoneal shunt was done before correction of FMEC in one patient (8.3%). The follow-up period ranged from 6 to 48 months with mean 29.2 months. The esthetic results were satisfactory in 9 patients (75%). Ugly facial scars were recorded in 3 patients (25%).

Conclusion: Early surgical management for FMEC is advisable to avoid deleterious effects on facial growth. Meticulous perioperative care is important for successful surgery. The authors recommend combined craniofacial approach to achieve good outcome and decrease the incidence of complications.
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http://dx.doi.org/10.1097/SCS.0000000000003157DOI Listing
January 2017

A Comparative Study of Single-pulse and Double-pulse Laser-Induced Breakdown Spectroscopy with Uranium-containing Samples.

Appl Spectrosc 2016 Mar 25;70(3):467-73. Epub 2016 Jan 25.

Center for Materials Under Extreme Environment (CMUXE), School of Nuclear Engineering Purdue University, West Lafayette, USA.

Laser-induced breakdown spectroscopy (LIBS) holds potential advantages in special nuclear material (SNM) sensing and nuclear forensics, which require rapid analysis, minimal sample preparation, and stand-off distance capability. SNM, such as U, however, result in crowded emission spectra with LIBS, and characteristic emission lines are challenging to discern. It is well-known that double-pulse LIBS (DPLIBS) improves the signal intensity for analytes over conventional single-pulse LIBS (SPLIBS). This study investigates the U signal in a glass matrix using DPLIBS and compares it to signal obtained using SPLIBS. Double-pulse LIBS involves sequential firing of a 1.06 µm Nd:YAG pre-pulse and 10.6 µm TEA CO2 heating pulse in a near collinear geometry. Optimization of experimental parameters including inter-pulse delay and energy follows identification of characteristic lines for the bulk analyte Ca and the minor constituent analyte U for both DPLIBS and SPLIBS. Spatial and temporal coupling of the two pulses in the proposed DPLIBS technique yields improvements in analytical merits with a negligible increase in damage to the sample compared to SPLIBS. Subsequently, the study discusses optimum plasma emission conditions of U lines and relative figures of merit in both SPLIBS and DPLIBS. Investigation into plasma characteristics also addresses plausible mechanisms related to the observed U analyte signal variation between SPLIBS and DPLIBS.
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http://dx.doi.org/10.1177/0003702815626670DOI Listing
March 2016

Atomic and optical properties of warm dense copper.

Phys Rev E Stat Nonlin Soft Matter Phys 2015 Sep 29;92(3):033109. Epub 2015 Sep 29.

Center for Materials under Extreme Environment, School of Nuclear Engineering, Purdue University, 400 Central Drive, West Lafayette, Indiana 47907-2017, USA.

The emission of x rays from warm dense matter is of great interest for both spectroscopic diagnostics and development of intense x-ray sources. We report the results from the collisional-radiative steady-state (CRSS) modeling of atomic and optical properties of copper plasmas at near-solid and solid-state density for a range of temperatures. The CRSS model is validated against the available data on the average charge state and shifts of energy levels in aluminum and the opacity and emissivity spectra of carbon and aluminum plasmas. The average charge states, number density of ion species, and free electrons as a function of temperature are investigated for the solid-density copper plasma. Due to the dense plasma environment the four outer electrons are found to be unbounded even in the low-temperature limit ∼1eV. As the temperature changes from 1 to 100 eV, the predominant species vary from fivefold- to twelvefold-ionized copper ions. The opacity and emissivity spectra of dense copper plasmas are studied using the local thermodynamic equilibrium (LTE) and non-LTE approaches. It is found that the non-LTE effects are important in the spectral region of soft x rays emitted from the K shell. The emissivity in spectral lines is completely suppressed, indicating the importance of the energy-dissipating radiative processes in this soft x-ray region. Line broadening and redshifts of the K- and L-shell spectral lines toward higher wavelengths are observed with the increase of plasma density. These results have important implications for understanding the radiative properties of warm dense copper and can be useful for future experimental studies.
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http://dx.doi.org/10.1103/PhysRevE.92.033109DOI Listing
September 2015

Prevalence, plasmids and antibiotic resistance correlation of enteric bacteria in different drinking water resources in sohag, egypt.

Jundishapur J Microbiol 2015 Jan 23;8(1):e18648. Epub 2015 Jan 23.

Department of Botany, Sohag University, Sohag, Egypt.

Background: One of the major health causing problems is contamination of drinking water sources with human pathogenic bacteria. Enteric bacteria such as Shigella, Salmonella and Escherichia coli are most enteric bacteria causing serious health problems. Occurrence of such bacteria infection, which may resist antibiotics, increases the seriousness of problem.

Objectives: The aim of this study was to examine the prevalence of some enteric bacteria (Shigella, Salmonella and E. coli) in addition to Pseudomonas. The antibiotic susceptibility of these bacteria was also tested, in addition to assessing plasmid(s) roles in supposed resistance. MRSA genes in non-staphylococci were clarified.

Materials And Methods: Water samples were collected from different drinking sources (Nile, ground water) and treated tap water. Selective media were used to isolate enteric bacteria and Pseudomonas. These bacteria were identified, counted and examined for its susceptibility against 10 antibiotics. The plasmids were screened in these strains. MRSA genes were also examined using PCR.

Results: Thirty-two bacterial strains were isolated from Nile and ground water and identified as S. flexneri, S. sonnei, S. serovar Newport, Pseudomonas aeruginosa and E. coli strains according to standard methods. According to antibiotic susceptibility test, 81% of strains were resistant to Cefepime, whereas 93.75% were sensitive to Ciprofloxacin. Correlation analysis between plasmids profiles and antibiotics sensitivities showed that 50% of the total strains had plasmids. These strains showed resistance to 50% of the used antibiotics (as average value); whereas, the plasmids free strains (50%) were resistant to 48.7% of the antibiotics. No distinct correlation between plasmids and antibiotic resistance in some strains could be concluded in this study. No MRSA gene was detected among these non-staphylococci strains. No bacteria were isolated from treated tap water.

Conclusions: Thirty-three bacterial strains; 10 strains of E. coli, 10 strains of S. flexneri, 3 strains S. sonnei, 2 strains of S. serovar Newport, and 7 strains of P. aeruginosa, were isolated and identified from Nile water and ground water in Sohag governorate. The prevalence of enteric bacteria in water sources in studying area was considerable. No clear or distinct correlation could be concluded between plasmids and antibiotic resistance. No MRSA gene was detected in these non-staphylococci strains, and no pathogenic bacteria were isolated from treated tap water. The hygiene procedures in the studying area seem to be adequate, despite the failure to maintain water sources form sewage pollution.
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http://dx.doi.org/10.5812/jjm.18648DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4344770PMC
January 2015

The influence of laser pulse duration and energy on ICP-MS signal intensity, elemental fractionation, and particle size distribution in NIR fs-LA-ICP-MS.

J Anal At Spectrom 2013;28:1420-1429. Epub 2013 Jun 5.

National Institute of Occupational Safety and Health, Cincinnati, OH 45213, USA.

Laser parameters, typically wavelength, pulse width, irradiance, repetition rate, and pulse energy, are critical parameters which influence the laser ablation process and thereby influence the LA-ICP-MS signal. In recent times, femtosecond laser ablation has gained popularity owing to the reduction in fractionation related issues and improved analytical performance which can provide matrix-independent sampling. The advantage offered by fs-LA is due to shorter pulse duration of the laser as compared to the phonon relaxation time and heat diffusion time. Hence the thermal effects are minimized in fs-LA. Recently, fs-LA-ICP-MS demonstrated improved analytical performance as compared to ns-LA-ICP-MS, but detailed mechanisms and processes are still not clearly understood. Improvement of fs-LA-ICP-MS over ns-LA-ICP-MS elucidates the importance of laser pulse duration and related effects on the ablation process. In this study, we have investigated the influence of laser pulse width (40 fs to 0.3 ns) and energy on LA-ICP-MS signal intensity and repeatability using a brass sample. Experiments were performed in single spot ablation mode as well as rastering ablation mode to monitor the Cu/Zn ratio. The recorded ICP-MS signal was correlated with total particle counts generated during laser ablation as well as particle size distribution. Our results show the importance of pulse width effects in the fs regime that becomes more pronounced when moving from femtosecond to picosecond and nanosecond regimes.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4673001PMC
http://dx.doi.org/10.1039/c3ja50088hDOI Listing
June 2013

Electroelastic coupling between membrane surface fluctuations and membrane-embedded charges: continuum multidielectric treatment.

J Chem Phys 2010 Jun;132(23):234707

School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907, USA.

The coupling of electric fields and charges with membrane-water interfacial fluctuations affects membrane electroporation, ionic conductance, and voltage gating. A modified continuum model is introduced to study charge interaction with membrane-water interfacial fluctuations in multidielectric environments. By surrounding a point charge with a low dielectric sphere, the linear Poisson-Boltzmann equation is directly solved by calculating the reaction field potential via a method that eliminates singularity contributions. This allows treatment of charges located at dielectric boundaries. Two complementary mechanisms governing charge-fluctuation interactions are considered: (1) electroelastic deformation (EED), treating the membrane as an elastic slab (smectic bilayer model), and (2) electrohydrophobic solvation (EHS), accounting for water penetration into the membrane's hydrophobic core. EED often leads to large membrane thickness perturbations, far larger than those consistent with elastic model descriptions [M. B. Partenskii, G. V. Miloshevsky, and P. C. Jordan, Isr. J. Chem. 47, 385 (2007)]. We argue that a switch from EED to EHS can be energetically advantageous at intermediate perturbation amplitudes. Both perturbation mechanisms are simulated by introducing adjustable shapes optimized by the kinetic Monte Carlo reaction path following approach [G. V. Miloshevsky and P. C. Jordan, J. Chem. Phys. 122, 214901 (2005)]. The resulting energy profiles agree with those of recent atomistic molecular dynamics studies on translating a charged residue across a lipid bilayer [S. Dorairaj and T. W. Allen, Proc. Natl. Acad. Sci. U.S.A. 104, 4943 (2007)].
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http://dx.doi.org/10.1063/1.3442414DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2907056PMC
June 2010

Shape-Dependent Global Deformation Modes of Large Protein Structures.

J Mol Struct 2010 May;972(1-3):41-50

School of Nuclear Engineering, Purdue University, West Lafayette, IN 47907, USA.

Conformational changes are central to the functioning of pore-forming proteins that open and close their molecular gates in response to external stimuli such as pH, ionic strength, membrane voltage or ligand binding. Normal mode analysis (NMA) is used to identify and characterize the slowest motions in the gA, KcsA, ClC-ec1, LacY and LeuT(Aa) proteins at the onset of gating. Global deformation modes of the essentially cylindrical gA, KcsA, LacY and LeuT(Aa) biomolecules are reminiscent of global twisting, transverse and longitudinal motions in a homogeneous elastic rod. The ClC-ec1 protein executes a splaying motion in the plane perpendicular to the lipid bilayer. These global collective deformations are determined by protein shape. New methods, all-atom Monte Carlo Normal Mode Following and its simplification using a rotation-translation of protein blocks (RTB), are described and applied to gain insight into the nature of gating transitions in gA and KcsA. These studies demonstrate the severe limitations of standard NMA in characterizing the structural rearrangements associated with gating transitions. Comparison of all-atom and RTB transition pathways in gA clearly illustrates the impact of the rigid protein block approximation and the need to include all degrees of freedom and their relaxation in computational studies of protein gating. The effects of atomic level structure, pH, hydrogen bonding and charged residues on the large scale conformational changes associated with gating transitions are discussed.
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http://dx.doi.org/10.1016/j.molstruc.2010.01.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2878971PMC
May 2010

Antiport mechanism for Cl(-)/H(+) in ClC-ec1 from normal-mode analysis.

Biophys J 2010 Mar;98(6):999-1008

School of Nuclear Engineering, Purdue University, West Lafayette, Indiana, USA.

ClC chloride channels and transporters play major roles in cellular excitability, epithelial salt transport, volume, pH, and blood pressure regulation. One family member, ClC-ec1 from Escherichia coli, has been structurally resolved crystallographically and subjected to intensive mutagenetic, crystallographic, and electrophysiological studies. It functions as a Cl(-)/H(+) antiporter, not a Cl(-) channel; however, the molecular mechanism for Cl(-)/H(+) exchange is largely unknown. Using all-atom normal-mode analysis to explore possible mechanisms for this antiport, we propose that Cl(-)/H(+) exchange involves a conformational cycle of alternating exposure of Cl(-) and H(+) binding sites of both ClC pores to the two sides of the membrane. Both pores switch simultaneously from facing outward to facing inward, reminiscent of the standard alternating-access mechanism, which may have direct implications for eukaryotic Cl(-)/H(+) transporters and Cl(-) channels.
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http://dx.doi.org/10.1016/j.bpj.2009.11.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2849085PMC
March 2010

Three-phase CFD analytical modeling of blood flow.

Med Eng Phys 2008 Jan 22;30(1):91-103. Epub 2007 Jan 22.

Mathematics and Computer Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA.

The behavior of blood cells in disturbed flow regions of arteries has significant relevance for understanding atherogenesis. However, their distribution with red blood cells (RBCs) and leukocytes is not so well studied and understood. Our three-phase computational fluid dynamics approach including plasma, RBCs, and leukocytes was used to numerically simulate the local hemodynamics in such a flow regime. This model has tracked the wall shear stress (WSS), phase distributions, and flow patterns for each phase in a concentrated suspension shear flow of blood. Unlike other computational approaches, this approach does not require dispersion coefficients as an input. The non-Newtonian viscosity model was applied to a wide physiological range of hematocrits, including low shear rates. The migration and segregation of blood cells in disturbed flow regions were computed, and the results compared favorably with available experimental data. The predicted higher leukocyte concentration was correlated with relatively low WSS near the stenosis having a high WSS. This behavior was attributed to flow-dependent interactions of the leukocytes with RBCs in pulsatile flow. This three-phase hemodynamic analysis may have application to vulnerable plaque formation in arteries with in vivo complex flow conditions.
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http://dx.doi.org/10.1016/j.medengphy.2006.12.004DOI Listing
January 2008

Nanopumping using carbon nanotubes.

Nano Lett 2006 Sep;6(9):1893-5

Argonne National Laboratory, Argonne, Illinois 60439, USA.

A new "nanopumping" effect consisting of the activation of an axial gas flow inside a carbon nanotube by producing Rayleigh traveling waves on the nanotube surface is predicted. The driving force for the new effect is the friction between the gas particles and the nanotube walls. A molecular dynamics simulation of the new effect was carried out showing macroscopic flows of atomic and molecular hydrogen and helium gases in a carbon nanotube.
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http://dx.doi.org/10.1021/nl060932mDOI Listing
September 2006

UV-vis, IR and 1H NMR spectroscopic studies of some 6-chloro,2-pyridyl hydrazones.

Spectrochim Acta A Mol Biomol Spectrosc 2006 Sep 9;65(1):206-14. Epub 2006 Mar 9.

Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt.

The electronic absorption spectra of some 6-chloro,2-pyridyl hydrazones are studied in seven organic solvents of different polarity. The absorption bands are assigned to the corresponding electronic transitions and the effect of solvent parameters on the charge transfer energy (E(CT)) is investigated. The spectra in buffer solutions of varied pH are also studied and utilized for the determination of the acid dissociation constants of the compounds under study. The fluorescence spectra were recorded for one of the studied compounds in six solvents, the solvent effect on the photoquantum yield and spectral pattern are also studied. Bands of diagnostic importance in the IR spectra and signals in the (1)H NMR spectra are assigned. The results of the present investigation are supported by some MO calculations using the atom super position and electron delocalization molecular orbital theory (ASED-MO) and Gaussian 94 program. The geometry is optimized using the PM3 method.
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http://dx.doi.org/10.1016/j.saa.2005.10.032DOI Listing
September 2006

Hemodynamic computation using multiphase flow dynamics in a right coronary artery.

Ann Biomed Eng 2006 Mar 15;34(3):393-407. Epub 2006 Feb 15.

Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA.

Hemodynamic data on the roles of physiologically critical blood particulates are needed to better understand cardiovascular diseases. The blood flow patterns and particulate buildup were numerically simulated using the multiphase non-Newtonian theory of dense suspension hemodynamics in a realistic right coronary artery (RCA) having various cross sections. The local hemodynamic factors, such as wall shear stress (WSS), red blood cell (RBC) buildup, viscosity, and velocity, varied with the spatially nonuniform vessel structures and temporal cardiac cycles. The model generally predicted higher RBC buildup on the inside radius of curvature. A low WSS region was found in the high RBC buildup region, in particular, on the area of maximum curvature of a realistic human RCA. The complex recirculation patterns, the oscillatory flow with flow reversal, and vessel geometry resulted in RBC buildup due to the prolonged particulate residence time, specifically, at the end of the diastole cycle. The increase of the initial plasma viscosity caused the lower WSS. These predictions have significant implications for understanding the local hemodynamic phenomena that may contribute to the earliest stage of atherosclerosis, as clinically observed on the inside curvatures and torsion of coronary arteries.
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http://dx.doi.org/10.1007/s10439-005-9017-0DOI Listing
March 2006

Multiphase hemodynamic simulation of pulsatile flow in a coronary artery.

J Biomech 2006 19;39(11):2064-73. Epub 2005 Aug 19.

Argonne National Laboratory, Energy Technology Division, Argonne, IL 60439-4815, USA.

A multiphase transient non-Newtonian three-dimensional (3-D) computational fluid dynamics (CFD) simulation has been performed for pulsatile hemodynamics in an idealized curved section of a human coronary artery. We present the first prediction, to the authors' knowledge, of particulate buildup on the inside curvature using the multiphase theory of dense suspension hemodynamics. In this study, the particulates are red blood cells (RBCs). The location of RBC buildup on the inside curvature correlates with lower wall shear stress (WSS) relative to the outside curvature. These predictions provide insight into how blood-borne particulates interact with artery walls and hence, have relevance for understanding atherogenesis since clinical observations show that atherosclerotic plaques generally form on the inside curvatures of arteries. The buildup of RBCs on the inside curvature is driven by the secondary flow and higher residence times. The higher viscosity in the central portion of the curved vessel tends to block their flow, causing them to migrate preferentially through the boundary layer. The reason for this is the nearly neutrally buoyant nature of the dense two-phase hemodynamic flow. The two-phase non-Newtonian viscosity model predicts greater shear thinning than the single-phase non-Newtonian model. Consequently, the secondary flow induced in the curvature is weaker. The waveforms for computed hemodynamic parameters, such as hematocrit, WSS, and viscosity, follow the prescribed inlet velocity waveforms. The lower oscillatory WSS produced on the inside curvature has implications for understanding thickening of the intimal layer.
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http://dx.doi.org/10.1016/j.jbiomech.2005.06.023DOI Listing
December 2006

Hyaluronic acid combined with mannitol to improve protection against free-radical endothelial damage: experimental model.

J Cataract Refract Surg 2005 Jun;31(6):1213-8

Vissum-Instituto Oftalmológico de Alicante, 03016 Alicante, Spain.

Purpose: To evaluate the protective properties of combined sodium hyaluronate 2% and mannitol 0.5% (Visiol) on the corneal endothelium in the presence of oxidative stress induced by hydrogen peroxide (H(2)O(2)).

Setting: Instituto Oftalmológico de Alicante, Universidad Miguel Hernández, Alicante, Spain.

Methods: This was an exploratory randomized controlled parallel-group, masked-assessor study of 3 sodium hyaluronate-based ophthalmic viscosurgical devices (OVDs): Visiol, Healon (sodium hyaluronate 1%), and Viscoat (sodium hyaluronate 3%-chondroitin sodium 4%). The OVDs were tested for protective effects on the endothelium following oxidative stress induced by H(2)O(2) at increased concentrations: control (lactated Ringer's solution), 1 mM, 10 mM, and 100 mM. Groups without OVD were used as controls at the same concentrations of peroxide. Each animal received the same treatment in both eyes (10 eyes per group). Endothelial cell lesion was assessed using the Janus green photometry absorbance technique.

Results: At 10 mM peroxide concentration, the value of endothelial cell lesion was significantly lower in the Visiol (16.8%, P=.0056), Healon (22.2%, P=.0302), and Viscoat (21.6%, P=.0336) groups than in the control group (29.4%, no OVD). There was a trend in favor of Visiol to more efficiently reduce cell lesions of the endothelium, than Healon (P=.055) and Viscoat (P=.1013). Values of endothelial cell lesion at peroxide concentrations of 1 mM and 100 mM showed the same trends than those observed at 10 mM.

Conclusions: All of the OVDs tested efficiently reduced endothelial lesions against free radicals compared with the control group in which no OVD was used. The following sequence for the efficacy of endothelial cell protection was established: Visiol>Viscoat>Healon>no OVD.
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http://dx.doi.org/10.1016/j.jcrs.2004.11.055DOI Listing
June 2005

One or 2 Intacs segments for the correction of keratoconus.

J Cataract Refract Surg 2005 May;31(5):943-53

Vissum/Instituto Oftalmológico de Alicante, Refractive Surgery and Cornea Department, Miguel Hernández University, 03016 Alicante, Spain.

Purpose: To evaluate the effect of implanting 1 or 2 intracorneal rings (Intacs, KeraVision) as a device to correct, stabilize, and/or improve the best corrected visual acuity in patients with clear cornea keratoconus oriented by the preoperative corneal topography pattern.

Setting: Vissum/Instituto Oftalmológico de Alicante, Miguel Hernandez University, Alicante, Spain.

Methods: In this prospective comparative consecutive study, Intacs segments were implanted in 26 keratoconic eyes with clear central corneas of 19 consecutive patients (9 women and 10 men). Corneas were divided into 2 groups according to the topographic pattern of the cone. Group I included keratoconus not crossing the 180 degrees meridian and Group II included keratoconus crossing the 180 degrees meridian. The Intacs were horizontally placed through a lateral clear corneal incision. According to the corneal topography 1 segment was implanted 0.45 mm inferior in Group I, and 2 segments were implanted, 1 0.25 mm superior and the other 0.45 mm inferior, in Group II. All cases completed a minimum follow-up of 1 year. Differences between preoperative and postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and keratometry were clinically and statistically evaluated.

Results: Spherical equivalent error and refractive astigmatism were significantly reduced. The mean keratometric values were reduced following Intacs insertion in both groups. At the end of the first year of the postoperative follow-up, Group I (1 segment) had an improvement in mean UCVA to 20/50 (0.4 +/- 0.22 decimal value), which was statistically significant when compared to the preoperative UCVA of 20/100 (0.2 +/- 0.13 decimal value) (P=.011). Mean BSCVA was 20/32 (0.62 +/- 0.24 decimal value), which was also statistically significant when compared to the preoperative BSCVA, which was 20/50 (0.4 +/- 0.21 decimal value) (P=.002). In Group II (2 segments), UCVA after 1 year was 20/63 (0.34 +/- 0.17 decimal value), which was statistically significant when compared to the preoperative UCVA of 20/400 (0.06 +/- 0.02 decimal value) (P=.001). Mean BSCVA was 20/32 (0.62 +/- 0.27 decimal value), which was significantly better than the preoperative UCVA of 20/50 (0.38 +/- 0.22 decimal value) (P=.001). In 4 eyes, the inferior segment was removed because of partial extrusion during the postoperative follow-up.

Conclusions: Treatment of keratoconus with 1 or 2 Intacs segments oriented by the preoperative corneal topography used in this study proved to be effective in decreasing the corneal steepening and astigmatism and improving BSCVA. Further follow-up is needed to determine the final effect of Intacs on the progression of the corneal disease.
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http://dx.doi.org/10.1016/j.jcrs.2004.09.050DOI Listing
May 2005

Changes in keratoconic corneas after intracorneal ring segment explantation and reimplantation.

Ophthalmology 2004 Apr;111(4):747-51

Refractive Surgery and Cornea Department, Instituto Oftalmológico de Alicante, Medical School, Miguel Hernández University, Avda. Denia 111, 03015 Alicante, Spain.

Purpose: To evaluate the outcome and potential reversibility of the changes induced in keratoconic eyes after intracorneal ring segment explantation.

Design: Retrospective, interventional case series.

Participants: Five eyes of 4 patients who underwent uneventful implantation of one or two intracorneal ring segment segments for the correction of clear corneal keratoconus and who required explantation of one segment due to complications.

Main Outcome Measures: Visual acuity, refraction, keratometric readings, and corneal topography. The follow-up was up to 1 year from the primary implantation procedure in all cases.

Results: Explantation was performed easily in all cases without intraoperative or postoperative complications. The segments were extracted due to migration and local melting. The visual, refractive, and topographic map findings regressed to approximate the original clinical situation before segment implantation.

Conclusions: Intracorneal ring segments are safely and easily explanted from keratoconic eyes. Most of the visual, refractive, and topographic findings return to near the preimplantation levels.
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http://dx.doi.org/10.1016/j.ophtha.2003.08.024DOI Listing
April 2004