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Neuroblastoma in Saudi Children: A Single Center Experience (2006-2014)  [PDF]
Zaid Al Naqib, Atif A. Ahmed, Musa Al Harbi, Fahad Al Manjomi, Zaheer Ullah Khan, Awatif Alanazi, Othman Mosleh, Walid Ballourah, Mohammed Rayis
Journal of Cancer Therapy (JCT) , 2015, DOI: 10.4236/jct.2015.610098
Abstract: Introduction: Neuroblastoma is the most common extracranial solid tumor in childhood and survival rate has improved during the last few decades. Only a few studies, related to Neuroblastoma in Saudi Arabian children, have been performed. We report epidemiologic data and our clinical experience from the department of Pediatric Hematology Oncology (PHO), King Fahad Medical City (KFMC), Riyadh, Saudi Arabia. Method: A retrospective observational study of all patients, with diagnosis of Neuroblastoma, who attended PHO-KFMC from July 2006 to June 2014 was performed. The survival periods (overall survival and disease-free survival) and the final outcomes for patients treated and followed at KFMC were recorded. The survival data were statistically correlated with the clinical, pathological and biological features of patients and tumors and compared to national and international cohorts. Results: Eight-year data were available for the 42 patients of which 22 (52.4%) were male and 20 (47.6%) were females. Age at diagnosis ranged 0 - 91 months with a mean and median of 26.3 and 18.5 months respectively. 16 (38.1%) patients were under one year and 26 (61.9%) above 1 year of age. The event-free survival (EFS) and overall survival (OS) rates were 66.5% and 71.5% respectively. EFS and OS among those who were <1 year age at presentation was 75% and 82%, whereas ≥1 yr age group had 59% and 62% survival rates respectively. Patients with tumors in the adrenal had considerably lower EFS (59%) and OS (63%); in comparison to patients with tumors sites other than the adrenal who had EFS and OS of 85% and 89% respectively. Both EFS and OS survival rates at the end of follow-up interval were 100.0%, in the low and intermediate risk groups. In contrast, patients in the high risk group had EFS and OS rates of 44% and 48% respectively. This difference was statistically significant (p < 0.05). Conclusion: Our results are very encouraging and comparable with known published international cohorts, and reveal an excellent outcome for stage 1, 2, 3 & 4 s. The prognosis for advanced (stage 4) disease remains rather poor. A collaborative Saudi-wide effort, with an emphasis on research in detecting clinical and biologic characteristics of aggressive disease and tailoring therapy, is needed.
Pediatric Non-Hodgkin Lymphoma: A Retrospective 7-Year Experience in Children & Adolescents with Non-Hodgkin Lymphoma Treated in King Fahad Medical City (KFMC)  [PDF]
Nahla Ali Mobark, Suha A. Tashkandi, Wafa Al Shakweer, Khalid Al Saidi, Suha A. Fataftah, Mohammed M. Al Nemer, Awatif Alanazi, Mohammed Rayis, Walid Ballourah, Othman Mosleh, Zaheer Ullah, Fahad El Manjomi, Musa Al Harbi
Journal of Cancer Therapy (JCT) , 2015, DOI: 10.4236/jct.2015.64033

Background: Non-Hodgkin’s lymphoma is an aggressive malignant disease in children and adolescents. Although it is the fourth most common malignancy in Saudi children as reported in Saudi cancer registry, less information is available about pediatric Non-Hodgkin lymphoma and its outcome in Saudi Arabia. Study Objectives: To provide demographic data, disease characteristics, treatment protocol, toxicity and outcome of treatment in children & adolescents with Non-Hodgkin’s lymphoma treated at KFMC. This study will form base line for future studies about pediatric Non-Hodgkin’s lymphoma in KFMC, which may help to improve outcome for children with cancer in Saudi Arabia. Study Patients and Method: We retrospectively analyzed 28 children and adolescents diagnosed to have Non-Hodgkin’s lymphoma at KFMC between December 2006 and December 2013, followed-up through June 2014. Results: Of the 28 patients, 10 (35.7%) girls and 18 (64.3%) boys, the male-to-female ratio was 1.8; 1. The median age at time of diagnosis was 6.4 years old (range 2.0 to 13.0 years old). The majority of patients (64.3%) were aged between 5 and 12 years old. Burkitt’s lymphoma BL/BLL was the most common pathological subtype (60.7%), and DLBCL was the second most common subtype (21.4%). Abdominal and Retroperitoneal involvement was the most common primary site (78.6%) including the ileocaecal region. Most of the children presented with advanced Stage III and IV (75%), Cytogenetic study which screens specifically for the t (8; 14) (q24; q32) a characteristic genetic feature of Burkitt’s Lymphoma was obtained from 21 patients, variant rearrangement was observed in 3/21 samples and complex chromosomes karyotype in addition to IGH/MYC rearrangement was observed in 2/21 samples. Those patients presented with very aggressive lymphoma and combined BM and CNS involvement. We use the French-American-British Mature B-Cell Lymphoma 96 Protocol (FAB LMB 96) for treatment fornewly diagnosed Mature B-Cell type NHL and high risk ALL CCG 1961 Protocol for lymphoblastic lymphoma and international Anaplastic Large Cell Lymphoma 99 Study Protocol for ALCL. The median follow-up in patients not experiencing an adverse event was 53.1 months. The estimated 3-year EFE and OS rates in the entire cohort of patients with newly diagnosed NHL treated in the KFMC were 85.2% and 89.2% respectively; Overall survival (OS) rate of patients with mature

Differentially-Keyed IR-UWB Signals for MA with Differential-Detection Receiver  [PDF]
Walid Mahmoud
Journal of Computer and Communications (JCC) , 2014, DOI: 10.4236/jcc.2014.28004

Noncoherent communication receivers (differential-detectors) have simple design, however, they always incur bit error rate (BER) performance loss up to 3dB compared to coherent receivers. In this paper, a differential-detector is proposed for impulse radio ultra wideband (IR-UWB) communication systems. The system employs bit-level differential phase shift keying (DPSK) combined with code division (CD) for IR-UWB signals to support multiple-access (MA). It is analyzed under additive white Gaussian noise (AWGN) corrupted by multiple-access interference (MAI) channel. Its BER performance is compared against a reference coherent receiver using Monte-Carlo simulation method. A closed form expression for its average probability of error is derived analytically. Simulation results and theoretical analysis confirm the applicability of the proposed differential-detector for IR-UWB communication systems.

The Relationship of SmokingOpioidAntidepressant Use and History of Spine Surgery  [PDF]
Walid Mohammad, Zaytseva Nadezhda
International Journal of Clinical Medicine (IJCM) , 2010, DOI: 10.4236/ijcm.2010.11003
Abstract: Introduction: In a recent paper, smoking was shown to be an independent predictor of longterm continued opioid use in spine patients (Krebs et al. 2010). In this paper, we study the interaction of smoking with opioid and antidepressant use and the relationship with prior spine surgery and future spine surgery. Methods: Data on smoking, opioid and antidepressant use were retrospectively collected from 758 spine surgery inpatients [lumbar microdiskectomy (LMD), anterior cervical decompression and fusion (ACDF) and lumbar decompression and fusion (LDF)]. Interaction with history of previous spine surgery and return for additional spine surgery was studied. Followup ranged from one to four years. Results: Significant correlation was detected between smoking and opioid use and between opioid and antidepressant use. History of previous spine surgery correlated with antidepressant use and return for additional spine surgery. Additional spine surgery correlated with opioid use and history of previous spine surgery. Smoking LMD patients on both opioids and antidepressants and smoking ACDF patients on antidepressants who have a history of prior spine surgery were more likely to return for additional spine surgery. However, in the LDF group, smoking patients on antidepressants without previous spine surgery were more likely to come for another spine surgery. Conclusion: Smokingantidepressantopioid use could be predictive of return for additional spine surgery during the followup years especially if a history of prior spine surgery was reported. Further research is needed on the implications of such an association.
Dependence of the GRB Lag-Luminosity Relation on Redshift in the Source Frame  [PDF]
Walid J. Azzam
International Journal of Astronomy and Astrophysics (IJAA) , 2012, DOI: 10.4236/ijaa.2012.21001
Abstract: The lag-luminosity relation for gamma-ray bursts (GRBs) is an anti-correlation between the time lag, ?lag, which represents the delay between the arrival of hard and soft photons, and the isotropic peak luminosity, L. In this paper, we use a sample of 43 Swift bursts, which was taken from Ukwatta et al., to investigate whether this relation depends on redshift. Both the z-correction and the k-correction are taken into account. Our analysis consists of binning the data in redshift, z, then applying a fit of the form: for each bin, where ?lag0 is the time-lag in the burst’s source frame, and is the corresponding mean value for the entire sample. The goal is to see whether the two fitting parameters, A and B, evolve in a systematic way with z. Our results indicate that both the normalization, A, and the slope, B, seem to vary in a systematic way with redshift. We note that although good best-fits were obtained, with reasonable values for both the linear regression coefficient, r, and the reduced chi-squared, the data showed large scatter. Also, the number of GRBs in the sample studied is not large, and thus our conclusions are only tentative at this point. A flat universe with M = 0.27, ?? = 0.73, and a Hubble constant, H0 = 70 km.s-1.Mpc-1 is assumed.
On the Security of Anonymous Authentication Protocol for Mobile Pay-TV  [PDF]
Walid I. Khedr
Journal of Information Security (JIS) , 2013, DOI: 10.4236/jis.2013.44025

One of the promising multimedia services is the mobile pay-TV service. Due to its wireless nature, mobile pay-TV is vulnerable to attacks especially during hand-off. In 2011, an efficient anonymous authentication protocol for mobile pay-TV is proposed. The authors claim that their scheme provides an anonymous authentication to users by preventing intruders from obtaining usersIDs during the mutual authentication between mobile subscribers and head end systems. However, after analysis, it was found that the scheme does not provide anonymous authentication and users can be easily tracked while using their anonymous identity. The scheme is also subject to denial of service attack. In this paper the deficiencies of the original scheme are demonstrated, and then a proposed improved scheme that eliminates these deficiencies is presented.

A Brief Review of the Amati Relation for GRBs  [PDF]
Walid J. Azzam
International Journal of Astronomy and Astrophysics (IJAA) , 2016, DOI: 10.4236/ijaa.2016.64030
Abstract: Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. Alt-hough the exact mechanism behind these explosions remains elusive, GRBs hold great promise as cosmological probes for two main reasons: they have been observed up to very high redshift (z > 9), and their gamma-ray emission is unencumbered by any intervening dust. Several GRB energy and luminosity indicators have been discovered. These indicators correlate an observable quantity, like the intrinsic peak energy, Ep,i, in the?\"\"spectrum of a burst to an unobservable parameter like the equivalent isotropic energy, Eiso, or the isotropic peak luminosity, Lp,iso. This paper provides a brief review of one of these energy and luminosity indicators, the Amati relation, and discusses its potential use as a cosmological probe.
Peak Energy Correlations for Gamma-Ray Bursts  [PDF]
Walid J. Azzam
Journal of Applied Mathematics and Physics (JAMP) , 2017, DOI: 10.4236/jamp.2017.58124
Abstract: Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. Over the past two decades, several GRB energy and luminosity correlations were discovered. These correlations typically involve an observable parameter, like the observed peak energy, Ep,obs, and a non-observable quantity, like the equivalent isotropic energy, Eiso. This paper provides a brief review of GRB peak energy correlations. Specifically, it focuses on the Amati relation, which correlates Ep,obs and Eiso, and the Ghirlanda relation, which correlates Ep,obs and Ey, the total energy corrected for beaming. The paper also discusses the physical interpretation of these relations in the context of the internal shock model.
Invariant Relative Orbits Taking into Account Third-Body Perturbation  [PDF]
Walid Ali Rahoma, Gilles Metris
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.32018
Abstract: For a satellite in an orbit of more than 1600 km in altitude, the effects of Sun and Moon on the orbit can’t be negligible. Working with mean orbital elements, the secular drift of the longitude of the ascending node and the sum of the argu-ment of perigee and mean anomaly are set equal between two neighboring orbits to negate the separation over time due to the potential of the Earth and the third body effect. The expressions for the second order conditions that guaran-tee that the drift rates of two neighboring orbits are equal on the average are derived. To this end, the Hamiltonian was developed. The expressions for the non-vanishing time rate of change of canonical elements are obtained.
Extra Investigation Might Be Necessary in High-Risk CT-Negative Cerebrovascular Cases  [PDF]
Mohammad Sami Walid, Nadezhda Zaytseva
Neuroscience & Medicine (NM) , 2013, DOI: 10.4236/nm.2013.42017

Cerebrovascular accidents occur in elderly patients in whom neurodegenerative changes increase the risk of vascular permeation and concomitant intracranial bleeding. In rare cases, intracerebral massive hemorrhage happens in hospitalized patients with apparently stable clinical picture. We report two cases illustrating this phenomenon, discuss the possible pathomechanism involved in those tragic incidents and suggest possible prevention measures for these patients. A negative CT image in a patient with neurological symptoms, especially who are on warfarin with or without considerably elongated coagulation time, may be subject to a sudden intracranial hemorrhage. Microvascular abnormalities might be detected on perfusion CT imaging and should therefore be performed in all CT negative patients with close observation for 24 hours before contemplating discharge.

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