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Search Results: 1 - 10 of 4224 matches for " Mohd Imtiaz Nawaz "
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Osteopontin and Other Regulators of Angiogenesis and Fibrogenesis in the Vitreous from Patients with Proliferative Vitreoretinal Disorders
Ahmed M. Abu El-Asrar,Mohd Imtiaz Nawaz,Dustan Kangave,Mohammed Mairaj Siddiquei,Karel Geboes
Mediators of Inflammation , 2012, DOI: 10.1155/2012/493043
Abstract: The aim of this study was to determine the levels of the angiogenic and fibrogenic factors osteopontin (OPN), high-mobility group box-1 (HMGB1), and connective tissue growth factor (CTGF) and the antiangiogenic and antifibrogenic pigment epithelium-derived factor (PEDF) in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), and rhegmatogenous retinal detachment with no PVR (RD). Vitreous samples from 48 PDR, 17 PVR and 30 RD patients were studied by enzyme-linked immunosorbent assay. OPN, HMGB1, CTGF, and PEDF levels were significantly higher in PDR patients than in RD patients ( ; 0.002; <0.001; <0.001, resp.). CTGF and PEDF levels were significantly higher in PVR patients than in RD patients ( , resp.). Exploratory logistic regression analysis identified significant associations between PDR and high levels of HMGB1, CTGF and PEDF, between PDR with active neovascularization and high levels of CTGF and PEDF, and between PDR with traction retinal detachment and high levels of HMGB1. In patients with PDR, there were significant correlations between the levels of PEDF and the levels of OPN ( ), HMGB1 ( ), and CTGF ( ). In patients with PVR, there were significant correlations between the levels of OPN and the levels of HMGB1 ( ) and PEDF ( ). Our findings suggest that OPN, HMGB1, and CTGF contribute to the pathogenesis of proliferative vitreoretinal disorders and that increased levels of PEDF may be a response to counterbalance the activity of angiogenic and fibrogenic factors in PDR and PVR. 1. Introduction Ischemia-induced pathologic growth of new blood vessels and expansion of extracellular matrix (ECM) in association with the outgrowth of fibrovascular epiretinal membranes at the vitreoretinal interface is the pathological hallmark in proliferative diabetic retinopathy (PDR) and often leads to catastrophic loss of vision due to vitreous hemorrhage and/or traction retinal detachment. Proliferative vitreoretinopathy (PVR) is a process of fibrocellular proliferation on either sides of the retina that may complicate rhegmatogenous retinal detachment. The formation and gradual contraction of epiretinal membranes causes a marked distortion of the retinal architecture and results in complex retinal detachments that are difficult to repair. Angiogenesis, the growth of new vascular networks from preexisting ones, is under tight regulation by a dynamic balance between angiogenic stimulators and inhibitors [1]. The biological process of fibrosis, typically associated with an abnormal accumulation
High-Mobility Group Box-1 and Endothelial Cell Angiogenic Markers in the Vitreous from Patients with Proliferative Diabetic Retinopathy
Ahmed M. Abu El-Asrar,Mohd Imtiaz Nawaz,Dustan Kangave,Marwan Abouammoh,Ghulam Mohammad
Mediators of Inflammation , 2012, DOI: 10.1155/2012/697489
Abstract: The aim of this study was to measure the levels of high-mobility group box-1 (HMGB1) in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR) and to correlate its levels with clinical disease activity and the levels of vascular endothelial growth factor (VEGF), the angiogenic cytokine granulocyte-colony-stimulating factor (G-CSF), the endothelial cell angiogenic markers soluble vascular endothelial-cadherin (sVE-cadherin), and soluble endoglin (sEng). Vitreous samples from 36 PDR and 21 nondiabetic patients were studied by enzyme-linked immunosorbent assay. HMGB1, VEGF, sVE-cadherin, and sEng levels were significantly higher in PDR patients than in nondiabetics ( ; <0.001; <0.001; 0.003, resp.). G-CSF was detected in only 3 PDR samples. In the whole study group, there was significant positive correlation between the levels of HMGB1, and sVE-cadherin ( , ). In PDR patients, there was significant negative correlation between the levels of sVE-cadherin and sEng ( , ). Exploratory regression analysis identified significant associations between active PDR and high levels of VEGF (odds ratio = 76.4; 95% confidence interval = 6.32–923) and high levels of sEng (odds ratio = 6.01; 95% confidence interval?= 1.25–29.0). Our findings suggest that HMGB1, VEGF, sVE-cadherin and sEng regulate the angiogenesis in PDR. 1. Introduction Ischemia-induced angiogenesis and expansion of extracellular matrix in association with the outgrowth of fibrovascular membranes at the vitreoretinal interface is the pathological hallmark in proliferative diabetic retinopathy (PDR). Vascular endothelial growth factor (VEGF), an endothelial cell mitogen that also enhances vascular permeability, is thought to be the major angiogenesis factor in PDR [1]. In addition, strong evidence indicates that chronic low-grade inflammation is implicated in the pathogenesis of diabetic retinopathy [2, 3]. Sustained proinflammatory responses in diabetic retinopathy are often associated with angiogenesis [2–5]. The causal relationship between inflammation and angiogenesis is now widely accepted [6]. An emerging issue in diabetic retinopathy research is the focus on the mechanistic link between chronic, low-grade inflammation and angiogenesis. High-mobility group box-1 protein (HMGB1) was initially discovered as a nuclear chromatin-binding protein that stabilizes nucleosome formation and facilitates transcription. Necrotic cell death can result in passive leakage of HMGB1 from the cell as the protein is then no longer bound to DNA. In addition, HMGB1 can be actively secreted by
Neurodegeneration and Neuroprotection in Diabetic Retinopathy
Mohammad Shamsul Ola,Mohd Imtiaz Nawaz,Haseeb A. Khan,Abdullah S. Alhomida
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14022559
Abstract: Diabetic retinopathy is widely considered to be a neurovascular disease. This is in contrast to its previous identity as solely a vascular disease. Early in the disease progression of diabetes, the major cells in the neuronal component of the retina consist of retinal ganglion cells and glial cells, both of which have been found to be compromised. A number of retinal function tests also indicated a functional deficit in diabetic retina, which further supports dysfunction of neuronal cells. As an endocrinological disorder, diabetes alters metabolism both systemically and locally in several body organs, including the retina. A growing body of evidences indicates increased levels of excitotoxic metabolites, including glutamate, branched chain amino acids and homocysteine in cases of diabetic retinopathy. Also present, early in the disease, are decreased levels of folic acid and vitamin-B12, which are potential metabolites capable of damaging neurons. These altered levels of metabolites are found to activate several metabolic pathways, leading to increases in oxidative stress and decreases in the level of neurotrophic factors. As a consequence, they may damage retinal neurons in diabetic patients. In this review, we have discussed those potential excitotoxic metabolites and their implications in neuronal damage. Possible therapeutic targets to protect neurons are also discussed. However, further research is needed to understand the exact molecular mechanism of neurodegeneration so that effective neuroprotection strategies can be developed. By protecting retinal neurons early in diabetic retinopathy cases, damage of retinal vessels can be protected, thereby helping to ameliorate the progression of diabetic retinopathy, a leading cause of blindness worldwide.
Relationship between Vitreous Levels of Matrix Metalloproteinases and Vascular Endothelial Growth Factor in Proliferative Diabetic Retinopathy
Ahmed M. Abu El-Asrar, Ghulam Mohammad, Mohd. Imtiaz Nawaz, Mohammad Mairaj Siddiquei, Kathleen Van den Eynde, Ahmed Mousa, Gert De Hertogh, Ghislain Opdenakker
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0085857
Abstract: To investigate which matrix metalloproteinases (MMPs) are more likely to be involved in the angiogenic process in proliferative diabetic retinopathy (PDR), we measured the levels of MMPs in the vitreous fluid from patients with PDR and controls and correlated these levels with the levels of vascular endothelial growth factor (VEGF). Vitreous samples from 32 PDR and 24 nondiabetic patients were studied by mosaic multiplex MMPs enzyme-linked immunosorbent assay (ELISA), single ELISA, Western blot and zymography analysis. Epiretinal membranes from 11 patients with PDR were studied by immunohistochemistry. MMP-8 and MMP-13 were not detected. ELISA, Western blot and gelatin ymography assays revealed significant increases in the expression levels of MMP-1, MMP-7, MMP-9 and VEGF in vitreous samples from PDR patients compared to nondiabetic controls, whereas MMP-2 and MMP-3 were not upregulated in vitreous samples from PDR patients. Significant correlations existed between ELISA and zymography assays for the quantitation of MMP-2 (r=0.407; p=0.039) and MMP-9 (r=0.711; p<0.001). Significant correlations were observed between levels of VEGF and levels of MMP-1 (r=0.845; P<0.001) and MMP-9 (r=0.775; p<0.001), and between levels of MMP-1 and MMP-9 (r=0.857; p<0.001). In epiretinal membranes, cytoplasmic immunoreactivity for MMP-9 was present in vascular endothelial cells and stromal monocytes/macrophages and neutrophils. Our findings suggest that among the MMPs measured, MMP-1 and MMP-9 may contribute to the angiogenic switch in PDR.
Analysis of User Specific Interleavers for Iterative Multi-User Detection System
Omer Nawaz,Waqas Nasir,Zia Bhadiar,Imtiaz Ahmed Khokhar
Lecture Notes in Engineering and Computer Science , 2007,
Abstract:
The Inhibitor U0126 Attenuates Diabetes-Induced Upregulation of MMP-9 and Biomarkers of Inflammation in the Retina
Ghulam Mohammad,Mohammad Mairaj Siddiquei,Mohammad Imtiaz Nawaz,Ahmed M. Abu El-Asrar
Journal of Diabetes Research , 2013, DOI: 10.1155/2013/658548
Abstract: This study was conducted to determine the expression of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in a time-dependent manner and the effect of extracellular-signal-regulated kinases-1/2 (ERK1/2) inhibition on the expressions of MMP-9, TIMP-1, and inflammatory biomarkers in the retinas of diabetic rats. The expression of MMP-9 was quantified by zymography, and the mRNA level of MMP-9 and TIMP-1 was quantified by RT-PCR. The expression of inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) was examined by Western blot analysis. MMP-9 expression was significantly higher in diabetic rat retinas compared to controls at all time points.TIMP-1 expression was nonsignificantly upregulated at 1week of diabetes and was significantly downregulated at 4 and 12 weeks of diabetes. Intravitreal administration of the ERK1/2 inhibitor U0126 prior to induction of diabetes decreased ERK1/2 activation, attenuated diabetes-induced upregulation of MMP-9, iNOS, IL-6, and TNF-α and upregulated TIMP-1 expression. In MMP-9 knockout mice, diabetes had no effect on retinal iNOS expression and its level remained unchanged. These data provide evidence that ERK1/2 signaling pathway is involved in MMP-9, iNOS, IL-6, and TNF-α induction in diabetic retinas and suggest that ERK1/2 can be a novel therapeutic target in diabetic retinopathy. 1. Introduction Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and remains one of the leading causes of blindness worldwide. DR is characterized by gradual progressive alterations in the retinal microvasculature, leading to loss of retinal capillary cells, disruption of vascular barrier, retinal nonperfusion, and preretinal neovascularization [1–4]. However, the exact molecular mechanisms, which mediate such response, remain largely unknown. In recent years, it has become evident that inflammatory mechanisms play an important role in the pathogenesis of DR, and proinflammatory mediators contribute significantly to the development and progression of DR [5–13]. Inflammation is a multistep process where proteases, growth factors, cytokines, and chemokines are released from retinal cells and interact with each other to promote inflammation in the diabetic retinal microenviroment. In the retina, it was shown that diabetes activates induction of proinflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1) [8], interleukin-6 (IL-6) [9], intercellular adhesion molecule-1 (ICAM-1) [10], inducible nitric oxide
Desulphurization of Transportation Fuels by Per-Formic Acid Oxidant Using MoOx Loaded on ZSM-5 Catalyst  [PDF]
Waqas Ahmad, Imtiaz Ahmad
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.512011
Abstract:
Desulphurization of model and real oil samples was investigated using performic acid as oxidant assisted by air as co-oxidant. The catalysts used were Mo-oxide supported on ZSM-5 zeolite, which was synthesized in the laboratory and characterized by FT-IR, XRD, SEM and SSA analysis. In case of model oil, the optimum condition determined for complete oxidation of all the model compounds including thiophene, DBT and 4,6-DMDBT were; 60?C, 60 min, ambient pressure and air flow rate of 100 mL/min. The oxidation reactivity decreased from 4,6-DMDBT to DBT and thiophene, which was found to follow pseudo first order kinetics. The real oil sample used in the study included untreated naphtha (NP), light gas oil (LGO), heavy gas oil (HGO) and Athabasca bitumen (Bit.). In case of NP and LGO the sulfur removal of above 78% was attained whereas in case of HGO and Bit. samples about 60% of desulfurization was achieved.
Self-Consistent C-V Characterization of Depletion Mode Buried Channel InGaAs/InAs Quantum Well FET Incorporating Strain Effects
Imtiaz Ahmed,Iftikhar Ahmad Niaz,Md. Hasibul Alam,Nadim Chowdhury,Zubair Al Azim,Quazi Deen Mohd Khosru
Physics , 2012, DOI: 10.1109/ICEDSA.2012.6507820
Abstract: We investigated Capacitance-Voltage (C-V) characteristics of the Depletion Mode Buried Channel InGaAs/InAs Quantum Well FET by using Self-Consistent method incorporating Quantum Mechanical (QM) effects. Though the experimental results of C-V for enhancement type device is available in recent literature, a complete characterization of electrostatic property of depletion type Buried Channel Quantum Well FET (QWFET) structure is yet to be done. C-V characteristics of the device is studied with the variation of three important process parameters: Indium (In) composition, gate dielectric and oxide thickness. We observed that inversion capacitance and ballistic current tend to increase with the increase in Indium (In) content in InGaAs barrier layer.
In_xGa_{1-x}Sb MOSFET: Performance Analysis by Self Consistent CV Characterization and Direct Tunneling Gate Leakage Current
Md. Hasibul Alam,Iftikhar Ahmad Niaz,Imtiaz Ahmed,Zubair Al Azim,Nadim Chowdhury,Quazi Deen Mohd. Khosru
Physics , 2012, DOI: 10.1109/EIT.2012.6220725
Abstract: In this paper, Capacitance-Voltage (C-V) characteristics and direct tunneling (DT) gate leakage current of antimonide based surface channel MOSFET were investigated. Self-consistent method was applied by solving coupled Schr\"odinger-Poisson equation taking wave function penetration and strain effects into account. Experimental I-V and gate leakage characteristic for p-channel InxGa1-xSb MOSFETs are available in recent literature. However, a self- consistent simulation of C-V characterization and direct tunneling gate leakage current is yet to be done for both n- channel and p-channel InxGa1-xSb surface channel MOSFETs. We studied the variation of C-V characteristics and gate leakage current with some important process parameters like oxide thickness, channel composition, channel thickness and temperature for n-channel MOSFET in this work. Device performance should improve as compressive strain increases in channel. Our simulation results validate this phenomenon as ballistic current increases and gate leakage current decreases with the increase in compressive strain. We also compared the device performance by replacing InxGa1-xSb with InxGa1-xAs in channel of the structure. Simulation results show that performance is much better with this replacement.
Developmental Response of Pieris brassicae (L.) (Lepidoptera: Pieridae) on Different Cauliflower Cultivars under Laboratory Conditions  [PDF]
Amna Sadozai, Imtiaz Ali Khan
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.518275
Abstract:

Cauliflower is popular vegetable in Pakistan and it is severely attacked by Pieris brassicae (L). There are different cauliflower cultivars available in this area. The aim of this study was to determine the developmental response of Pieris brassicae on ten cauliflower cultivars. An experiment was conducted during 2012-13 at the Entomology section of the Agriculture Research Institute Tarnab Peshawar under laboratory conditions of 20°C ± 2°C, 50% ± 5% RH and 12:12h photoperiod. Pieris brassicae eggs were collected from a cauliflower field ARI Tarnab and the larvae placed after hatching on fresh leaves often cauliflower cultivars. The results showed that the larval development of P. brassicae was short (35 days), longer larval length (32.41 mm), larval mortality was low (6.6%) and pupal weight was high (0.50 g) on Clima cultivar. On the other hand, a longer larval developmental period (37 days), higher larval mortality (86.66%), shorter larval length (24.55 mm) and lower pupal weight (0.42 g) were recorded on cultivar AX-2034.

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