Pattern Recognition Using Neural Network Essay Example | Topics and Well Written Essays - 3000 words

Pattern Recognition Using Neural Network - Essay Example Pattern Recognition or Optical Character Recognition (OCR) is a pipelined process consisting of several stages in proper sequence. They are shown in figure 2. Each character is represented as a combination of pixels. All pixels together make a huge feature vector. Total number of pixels is equal to wh where w is the number of pixel in width side and h is the pixels present in height. Figure 3 depicts the way pixel forms one particular character. xi is the fraction of ink in pixel i. Classifier must be adaptive (generalize) in nature so that it can be able to recognize patterns encountering first time. A typical character image is 6464 pixels large and for each such pixel 256 grey values are required making feature space large. For training a recognizer hence, requires huge amount of data to fill this vast space. In order to reduce the dimension space Principal Component Analysis is mostly used which transforms into lower dimension space (Yeung & Ruzzu, 2001). OCR also should make a distinguishing between 'O' and '6'. Figure 4 shows one case example. If t/b comes smaller that means letter is 'O' otherwise '6'. A good algorithm must define the tolerance level (T) adequately. Other examples of such cases are letter 'q' and digit '9'. There are various algorithm or computer processes available for pattern recognition. One such example is Brian Sanderson's Pattern Recognition (PR) Algorithm. Every patter is identified according to three systems of notation:333 Conway Thurston Notation. P3 The International Union of Crystallography notation. S333 The Montesinos Notation First identify the maximum rotation number whether it is 1, 2, 3, 4 or 6. Then check any mirror is present or not (m). Is there any indecomposable glide reflection (g) And finally whether there is any rotation axis on the mirror present or not. Other than this Genetic Algorithm also works as PR. Selection of patterns play an important role in PR process as it determines the accuracy of algorithm, its learning time, and the necessary number of samples. Best selection of feature plays important role at the time developing classifiers. The problem comes out more difficult when number of features become very large. Genetic Algorithm (GA) gives better result in that. As they are effective in rapid global search of large, nonlinear and sparsely spaced points, GA is applied for feature recognition problem. It combines different optimization problem into a single formulation problem (Morita). Most effective approach today for OCR is Neural Network based recognition. Neural Network: An Overview A Neural network is a massively parallel distributed processor made up of simple processing units, which has a natural propensity for storing experimental knowledge and making it available for use. It resembles the brain

Examine the nature of the distinctive managerial, organisational and Essay

Examine the nature of the distinctive managerial, organisational and developmental characteristics of small businesses vis-a-vis - Essay Example Coaching is more task-oriented whereas mentoring is driven by knowledge sharing meant in a spiritual context with the purpose of developing the personality of a learner. The understanding developed through the work of Garvey et al. (2008) is further strengthened through literary explanation provided by Robert Thurman, Meredith Belbin and Rosemary Ryan. Where Garvey et al. (2008) describes how the definitions of these two terms have evolved over centuries, other three authors explain their relevance to present life. According to Garvey et al. (2008), self-realization is a foundation of coaching and mentoring. The follower has to understand his/ her inner self and then interpret the meaning of knowledge provided to them. Furthermore, they believe that coaching and mentoring are rooted in our cultural norms and values. Like Bruner stated in Garvey et al. (2008), folk wisdom is distributed through interpretations of historical events that later on form our culture; this understanding of cultural norms is further strengthen through dialogues (p.11). In order to elaborate the historical background of coaching and mentoring, frequent references to the work of Plato, Homer, Socrates and Aristotle are given in Garvey et al. (2008). It is stated that frequent questioning and critical debates lead to emergences of true knowledge. Therefore, without questioning the pre-established norms, new ideas cannot be created. While defining their work, it was found that only Plato and Aristotle have used the word mentor for a figure known for disseminating knowledge. Later on, it has been added that Aristotle has introduced a differentiation between practical and theoretical knowledge. He further introduced the concept of productive work which defines creation of something new. Careful analysis of contemporary coaching techniques would reveal that these three concepts are used frequently in present coaching and mentoring. Further referencing to Homer indicated that the word mentor w as introduced into literature around three thousand years back. The word itself meant an advisor. However, Homer’s work has been highly shadowed by unnecessary criticism and relevance to gender issues without giving much attention to social norms. Garvey et al. (2008) further analyzed the literary work with reference to coaching and mentoring in 18th century. According to Fenelon, observing life events is itself a learning process that can provide positive as well as negative lessons. Presence of mentor helps in interpreting important lessons out of these events that helps in attaining better insight of life and virtues. The concept of experiential learning also stemmed out of Fenelon’s ideas of learning and development. The idea was extended by Rousseau in 18th century when he introduced the ideal class size for effective education. The present day concept of multiple students in one group headed by a single teacher was not accepted by Rousseau; in fact he emphasized on having a one-on-one interaction between the student and a teacher whereas the term teacher was replaced by mentor. Where mentor was considered as a figure of knowledge and wisdom, Louis Carccioli attached spiritual attributes to this personality. According to him, a mentor is someone who not only enriches the mind but also lights the heart. Hence, a therapeutic effect of mentoring was introduced by Caraccioli when he writes, â€Å"

Types of Mitochondrial Diseases

Types of Mitochondrial Diseases Abstract: Mitochondrion is the primary site of energy and ATP generation so it is called â€Å"power house† of the cell. Mitochondria are composed of two different types of membranes like an outer membrane, an inner membrane and a protein-rich matrix. Protein kinases can localize to specific cytoplasmic sub compartments and mediates many important processes like cell motility and many signaling events. The mitochondrion is a point of integration for these signaling cascades due to its role in cellular metabolism, redox processes, and cell survival-death. PI3K/Akt/Protein Kinase B(PKB) ,Protein kinase C(PKC),Raf-MEK-ERK,JNK/SAPK and p38 MAPK, Apoptosis signal-regulating kinase 1 (ASK1),Glycogen synthase kinase 3ÃŽ ² (GSK-3ÃŽ ²),Protein kinase A (PKA),PTEN-induced kinase 1 (PINK1) are associated with mitochondria and modulate mitochondrial activity and the release of mitochondrial products affects mitochondrial respiratory chain, transport, fission-fusion events, calcium turnover, reactiv e oxygen species (ROS) production, mitochondrial autophagy and apoptotic cell death. Mitochondrial diseases are due to degeneration of the mitochondria in specialized compartments present in every cell of the body. Mitochondria diseases causes damage to cells of the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. So this review focuse on various kinases associated with mitochondria, their role in progression of neurodegenerative diseases and treatment. Introduction 1 Mitochondria: Mitochondrion is present in every eukaryotic cell having size range of 0.5 to 10 ÃŽ ¼m in diameter (Munn et al., 1974). It is the primary site of energy and ATP production so it is called â€Å"power house† of the cell. Mitochondria are composed of two different types of membranes like an outer membrane, an inner membrane and a protein-rich matrix. The molecular machinery of chemiosmosis is associated with the inner membrane. Mitochondrial energy production is same in all cells but there are variations in shape, connectivity, and membrane morphology (Munn et al., 1974, Fawcett et al., 1966). There might be changes in the â€Å"energization† state of the mitochondrial membrane integral to energy production (Green et al., 1973). Structural diversity and dynamics of mitochondria were studied with the help of light and electron microscopy and their relationship with other cellular components. This technique gives idea about changes in shape and structure of mitochondria dur ing biological processes. Electron tomography shows remodeling of the inner membrane in the case of apoptosis and cytochrome c release (Scorrano et al., 2002) and mitochondrial fragmentation (Sun et al., 2007). Cell controls the mitochondrial structure, its function and response against various stimuli (Mannella et al., 2006) 1.1 Structure: A mitochondrion has double layer structure composed of phospholipids and proteins (Munn et al., 2007). These two double membranes have five compartments like the outer membrane, the intermembrane space ( between the outer and inner membranes), the inner membrane, the cristae formed by unfolding of the inner mitochondrial membrane, and the matrix (space in the inner mitochondrial membrane). 1.2 Inner Mitochondrial membrane: The inner membrane contains invaginations called cristae. The cristae are not random folds but these are small regions that open through narrow tubular channels into the peripheral region of the membrane (Fig. 2) (Mannella et al., 2001). Topographic analysis of intact, frozen-hydrated, rat liver mitochondria(Mannella et al., 2001) describes the inner diameter of the tubular â€Å"cristae junctions† is 10-15 nm (Fig. 2).This is enough to pass metabolites and many soluble proteins and the inner membrane restrict internal diffusion rates. For example, computer simulations indicate that the steady-state level of ADP inside cristae with long small junctions can drop below the Km for the adenine nucleotide translocator, leading to a local drop in ATP generation. Like that truncated (t)-Bid-induced remodeling in the inner mitochondrial membrane of isolated mouse liver mitochondria (Fig. 2) causes mobilization of a large fraction of the internal pool of cytochrome c lead to increased rates of reduction by the NADH cytochrome b5 redox system on the outer membrane of the organelle(Scorrano et al.,2002).The inner-membrane remodeling involves fivefold widening of the cristae and diffusion of cytochrome c between intracris tal and peripheral (intermembrane) compartments. These shows that the topology of the mitochondrial inner membrane can have effect on mitochondrial functions by influencing the kinetics of diffusion of metabolites and soluble proteins between the internal compartments defined by this membrane (Mannella et al., 1997). 1.3 Mitochondrial Inner-membrane Dynamics: Isolated mitochondria has two morphologic states, condensed and orthodox.Condence state is characterized by a contracted, very dense, matrix compartment and wide cristae while orthodox having an expanded, less-dense matrix and more compact cristae(Hackenbrock et al.,1966 ). Changes between these two morphological states has been detected in real time by light scattering or simply by adjusting the osmotic pressure of the external medium, causing water to flow into or out of the matrix. A reversible condensed-to-orthodox transition also occurs during respiration when ADP is in excess amount and fully phosphorylated form (Hackenbrock et al., 1966). Electron micrograph shows changes in inner mitochondrial membrane as passive unfolding and refolding of the inner membrane. 3D images of rat liver mitochondria obtain by electron tomography indicate that condensed rat liver mitochondria have large pleiomorphic cristae and multiple junctions to each other and to the peripheral region of the inner membrane, that is the region opposed to the outer membrane and the Orthodox rat liver mitochondria have cristae either tubular or flattened lamellae, both types usually having only one junction to the periphery of the inner membrane. For this to occur the inner mitochondrial membranes must undergo fusion and fission, with tubular forms merging into the larger cisternae during matrix condensation. Large lamellar compartment are formed via cristae fusion is strongly suggested by their appearance in tomograms of frozen-hydrated mitochondria (Fig. 2).so that the structural variations that mitochondria undergo in response to osmotic and metabolic changes involve not only the contraction and dilation of the matrix and intracristal space but also by remodeling of the inner mitochondrial membrane. A review of mitochondrial morphologies associated with a variety of osmotic, metabolic, and disease states suggests that inner-membrane topology represents a balance between fusion and fission, with defects (such as crista vesiculation) corresponding to an imbalance in this process (Mannella et al.,2006). 1.4 Inner mitochondrial membrane proteins: Mitochondrial proteins responsible for maintenance of normal cristae morphology and dynamics are also responsible for mediate inter mitochondrial fusion and organelle division since these processes involve fusion and fission of the inner as well as the outer membranes. For example, the dynamin-like GTPase called Mgm1p in yeast and OPA1 in mammalian cells is required for the fusion of mitochondria. Mutations in this protein cause a progressive, autosomal, dominant retinopathy, dominant optic atrophy (Alexander et al.,2000, Delettre et al.,2002) giving the physiological importance of mitochondrial dynamics. Another protein that directly influences inner-membrane topology is F1F0 ATP synthase. Mutations in subunits e or g of the F0 domain cause lateral dimerization and subsequent oligomerization of these inner membrane complexes and are associated with wrapped cristae lacking tubular junctions (Paumard et al., 2002). This also occurs with the down regulation of the protein mitofilin tha t regulate interactions of the ATP synthase (John et al., 2005). In ATP synthase dimers, close packing of the bulky extra membrane F1 domains causes the smaller, intramembrane F0 domains , which could induce local bending of the inner membrane.Mgm1/OPA1 has a chaperone-like function for subunit e of the ATP synthase. The loss of the function of Mgm1/OPA1 mutants inhibits ATP synthase dimer formation, which lead to the deficiency of normal tubular crista junctions in these mitochondria. 2 Mitochondrial kinases: Activated protein kinases can localize to specific cytoplasm sub compartments and mediates many important processes like cell motility (Glading et al., 2001), and signaling endosomes may facilitate communication between neurons(Howe CL et al.,2004). Like hormone- or growth factor-induce signaling cascades, recent advances in redox signaling pathways have very complex function. The mitochondrion is a point of integration for these redox signaling cascades due to its role in cellular metabolism, redox biochemistry, and survival-death decisions. Recent studies have demonstrated that certain components of protein kinase signaling cascades are specifically targeted to mitochondria, where they modulate mitochondrial activity and the release of mitochondrial products that ultimately affect the entire cell. 3 List of Mitochondrial kinases: PI3K/Akt/Protein Kinase B(PKB) Protein kinase C(PKC) Raf-MEK-ERK JNK/SAPK and p38 MAPK Apoptosis signal-regulating kinase 1 (ASK1) Glycogen synthase kinase 3ÃŽ ² (GSK-3ÃŽ ²) Protein kinase A (PKA) PTEN-induced kinase 1 (PINK1) (1) PI3K/Akt/Protein Kinase B(PKB) The protein kinase B (serine/threonine kinase Akt) has a major role in cell proliferation and survival in many cells of the body. Akt is activated by phosphoinositide-dependent kinases to the plasma membrane by products of the type I phosphoinositide 3- kinase (Vanhaesebroeck et al., 2000). Antiapoptotic effects of nitric oxide may be partially mediated by cGMPdependent activation of phosphoinositide 3-kinase and Akt (Ha KS et al., 2003). Inspite of direct effects of Akt in phospho-inactivating the proapoptotic protein BAD (Datta et al., 1997), Akt also activate Raf-1 in the mitochondria (Majewski et al., 1999) and cause expression of proteins involved in the mitochondrial permeability transition pore(Nebigil et al.,2003). Akt can also having role in cell survival through regulation of forkhead transcription factors (Linseman et al., 2005). In Neuroblastoma and human embryonic kidney cells, insulin-like growth factor 1 Cause rapid translocation of phospho-Akt into mitochondrial subcellular fractions (Bijur et al., 2003). This effect may be cell type specific, as Akt was not observed in mitochondria of mesangial cells stimulated by insulin-like growth factor 1(Kang et al.,2003). Activated mitochondrial Akt can also phosphorylate ÃŽ ² subunit of ATP synthase and of glycogen synthase kinase 3ÃŽ ² (GSK3ÃŽ ²) (Bijur et al., 2003). GSK3ÃŽ ² has been localized by immunoelectron microscopy to the mitochondria, where it functions to phosphorylate and inhibit mitochondrial pyruvate dehydrogenase activity (Hoshi M et al., 1996) and to promote apoptosis (Hetman et al., 2000). Akt can localize within the mitochondria rather than on its surface most commonly in the mitochondrial membrane fractions and to a lesser degree in the matrix (Bijur et al., 2003). It has pro survival role in mitochondrial membrane permeation. The antioxidant selenite has neuroprotective effects and increases AKT activation by PI3K (Wang et al., 2007). Inhibition of PI3K enhance RGCs survival upon axotomy, in a fashion that depended on the presence of local macrophages PI3K inhibition suppressed the neuroprotective effects of sodium Orthovanadate (Wu et al., 2006). (2) Protein kinase C (PKC) The protein kinase C (PKC) family consists of multiple isozymes with distinct distribution patterns in different tissues of the body (Dempsey et al., 2000). Extracellular ligand binds to a receptor tyrosine kinase or G protein-coupled receptor activates phospholipase C and produces inositol triphosphate (IP3) and diacylglycerol (DAG). Calcium released by IP3 causes PKC to bind to membranes, where DAG then activates PKC. Activated PKC phosphorylates many cellular targets, including c-Fos and NF-ÃŽ ºB. The isozymes of PKC differ not only in their localization but also in their responsiveness to IP3, DAG, and calcium. There are three subgroups of PKC isoforms, conventional, novel, and atypical, classified on the basis of their responsiveness to these regulators (Parker et al., 2004). The ÃŽ ± and ÃŽ ² isoforms of PKC were found in a subset of mitochondria in carp retinal Mà ¼ller cells (Fernandez et al., 1995) Immunoelectron microscopy studies showed that the kinase was associated with the inner membrane and cristae. Researchers described that PKC isoforms play a direct role in regulating mitochondrial function. Activated PKC isoforms that translocate to the mitochondria are proapoptotic or inhibitory to mitochondrial function. For example, renal proximal tubular cells respond to oxidative stress by activated PKCÃŽ µ to the mitochondria and inhibit the electron transport chain, ATP production, and Na+ transport by direct phosphorylation of Na+-K+-ATPase (Nowak et al., 2004). Treatment of various neoplastic cells with phorbol esters, H2O2, or anticancer agents such as cisplatin and etoposide causes accumulation of PKCÃŽ ´ to the mitochondria, with subsequent releases cytochrome c and induction of apoptosis (Majumder et al., 2000). In rat cardiac myocytes PKCÃŽ ´ was shown to move to the mitochondria in response to anesthetic exposure or ischemia/reperfusion. PKCÃŽ ´ then activate mitochondrial KATP channels, which then promote cardio protection (Uecker et al., 2003). PKCÃŽ µ also promotes cardioprotection following ischemia/reperfusion through a different mechanism, phosphorylating the voltage dependent anion channel (VDAC) component of the mitochondrial permeability transition pore (Baines et al., 2003). This prevents mitochondrial swelling, outer membrane rupture, release of apoptogenic factors, and decreases in ATP production. PKCÃŽ µ and extracellular signal-regulated kinases (ERKs) interact at the mitochondria to inactivate the proapoptotic protein BAD in cardiac myocytes (Baines et al., 2002). Inactivation of the proapoptotic protein Bax by PKCÃŽ µ in prostate cancer cells renders these cells resistant to androgen-deprivation therapy (McJilton et al., 2003). PKC isoforms translocate from one cell compart ment to another, these responses to PKC signaling may be mediated by association with specific anchoring scaffold proteins, RACKs (receptors for activated C kinase) and RICKs (receptors for inactive C kinase) (Mochly-Rosen et al., 1998). (3) ERK-Raf-MEK The extracellular signal regulated protein kinases (ERK1/2) has a role in regulating the processes like proliferation, differentiation, adaptation (i.e., cell motility, long term potentiating), survival, and even cell death. ERK has been found in the mitochondria of neurons and non-neuronal cells such as in mouse heart, renal epithelial cells, outer membrane and the intermembrane space of rat brain mitochondria, mouse hippocampus, B65 cells, SH-SY5Y cells; Leydig cells and human alveolar macrophages (Ruben K et al., 2009).The three-tiered ERK signaling involves sequential activation of Raf (MAPKKK), MEK1/2 (MAPKK), and ERK1/2 (MAPK). Depending on its intracellular localization and pathway of activation, Raf-1 can affect apoptosis by different mechanisms (Majewski et al.,1999, Alavi et al., 2003).ERK signaling can have opposite responses to injury even within the same cell type (Chu et al., 2004, Hetman et al., 2004). It has Pro-apoptotic role in mitochondrial membrane permeation. Pha rmacological inhibition of ERKs resulted in a reduction of cortical lesion volumes one week after trauma (Mori et al., 2002). Intravenous administration of a specific inhibitor of MEKs after ischemia results in decrease of infarct volume (Namura et al., 2001). The antiapoptotic protein Bcl-2 plays an important role in targeting Raf-1 to the mitochondria, resulting in phosphorylation of proapoptotic BAD, provides evidence for signaling roles for plasma membrane-targeted versus mitochondrially targeted Raf proteins (Wang et al., 1996). Signaling cascade consisting of Raf-1, MEK1, and the adapter protein Grb10 have been localized to mitochondrial membranes (Nantel et al., 1999). The antiapoptotic effects of mitochondrially localized Raf-1 are independent of ERK activity in myeloid cells (Majewski et al., 1999), and MEK/ERK signaling does mediate antiapoptotic effects of B-Raf in fibroblasts (Erhardt et al., 1999). Phosphorylation of S338 and S339 on Raf-1 promotes mitochondrial translocation and protection of endothelial cells from the intrinsic pathway of apoptosis, whereas Src cause phosphorylation of Y340 and Y341 and MEK/ERK activity are important for protection from death receptor-initiated cell death (Alavi et al., 2003). ERK can modulate mitochondrial functions and inhibition of MEK, those associated with cell death. For example, ERK signaling promotes mitochondrial ATP synthase function in glucose-deprived astrocytes (Yung et al., 2004), to maintain mitochondrial membrane potential and prevent cytochrome c release (Lee et al., 2004), and to inactivate the proapoptotic protein BAD (Jin et al., 2002). ERK has also role in promoting oxidative neuronal injuries (Chu et al., 2004) and in neurodegenerative diseases (Tobiume et al.,2002, Kulich et al.,2001) MEK/ERK promotes organophosphate induce mitochondrial vacuolation(Isobe et al., 2003), apoptotic translocation of Bax to the mitochondria(Isobe et al., 2003), and nonapoptotic programmed cell death(Sperandio et al., 2004). As pro- and antiapoptotic effects of MEK/ ERK signaling could be mediated by downstream targets or at the transcriptional level (Bonni et al., 1999), these studies do not necessarily indicate mitochondrial targeting of ERK. Mitochondrial targeting of ERK signaling was first derived from biochemical subcellular fractionation studies. In renal tubular cells, both activated ERK1/2 and PKCÃŽ ± are enriched in mitochondrial fractions during cisplatin injury, where they increase mitochondrial membrane potential, decrease oxidative phosphorylation, and increase caspase-3 activation and apoptosis (Nowak et al., 2002).ERK activity in phosphorylating both Bcl-2(Deng et al., 2000) and BAD (Kang et al., 2003) are associated with increased levels of activated ERK colocalizing or co-immunoprecipitating with the Bcl-2 family members in mitochondria. Immuno-electron microscopy studies shows presence of phosphorylated ERK1/2 within the mitochondrion (Zhu et al., 2003, Alonso et al., 2004). Phospho-ERK was found at high labeling densities within a subset of mitochondria in degenerating neurons from patients of Parkinsons disease and Lewy body dementia (Chu et al., 2003) and distinct granular cytoplasmic pattern of staining are not observed in control patients(Zhu et al., 2002). (4) JNK/SAPK and p38 MAPK The p38 MAPKs and the JNK (c-Jun N-terminal kinase) / SAPK (stress-activated protein kinase) are of MAPK family membranes and involved in prodeath signaling (Matsuzawa et al., 2001). The p38 and JNK are activated by a MAP kinase (MKK), which is activated by a MAPKKK in response to a stimulus like oxidative stress, irradiation, or proinflammatory cytokines such as tumor necrosis factor ÃŽ ±. Role of p38 MAPK signaling in cell death includes translocation of proapoptotic Bax from cytosolic to mitochondrial compartments (Park et al., 2003 Shou et al., 2003), caspase-independent potassium efflux (Bossy-Wetzel et al., 2004), and transcriptional regulation of TR3, a steroid receptor-like protein that translocates from the nucleus to the mitochondria to initiate the intrinsic apoptotic pathway (Bossy-Wetzel et al., 2004). Irradiation causes translocation of both p38 and JNK1 to mitochondrial subcellular fractions (Epperly et al., 2002). The effects of JNK on the mitochondria involve stimulation of apoptosis. Treatment of isolated rat brain mitochondria with active JNK causes the inhibition of antiapoptotic Bcl-2 and Bcl-xL and release of cytochrome c (Schroeder et al., 2003). The mitochondrial JNK is activated by oxidative stress in cardiac myocytes, and cause the release of cytochrome c lead to apoptosis (Aoki et al., 2002). Treatment with phorbol esters cause localization of JNK to the mitochondria in human U-937 leukemia cells, where it binds to and inhibits Bcl-xL, promoting apoptosis (Kharbanda et al., 2000, Ito et al., 2001). Mitochondrial JNK can also cause the release of Smac, the activator of caspase that promotes caspase-9 activity (Chauhan et al., 2003). JNK also phosphorylates and oligomerize proapoptotic BAD (Bhakar et al., 2003). JNK signaling can yield cell survival under some conditions. JNK can inactivate the pro-apoptotic protein BAD (Yu C et al., 2004). Activated JNK phosphorylates Bcl-2 at Ser70 in the mitochondrial membranes of interleukin-3-dependent hematopoietic cells. This occurs under conditions of stress or by exposure to interleukin-3, resulting in enhanced antiapoptotic activity of Bcl-2(Deng et al., 2001). It has Pro-apoptotic role in mitochondrial membrane permeation. JNK3 (but not JNK1 nor JNK2) absence conferred significant neuroprotection to axotomized neurons. The absence of JNK3 (but not of JNK1 nor of JNK2) resulted in a substantial resistance against kainate-induced seizures, which correlated with improved survival (Brecht et al., 2005). Pharmacological JNK inhibitors diminished several manifestations of apoptosis and reduced infarct volume (Gao et al., 2005). Intravitreal administration of a p38MAPK inhibi tor induced apoptosis (Kikuchi et al., 2000). Oral administration of a p38MAPK inhibitor during pre- and post-ischemia provided dose-dependent neuroprotective effects (Legos et al., 2001). Pharmacological inhibition of p38MAPK protects neurons from NO-mediated degeneration (Xu et al., 2006). (5) Apoptosis signal-regulating kinase 1 (ASK1) All living systems are exposed to numerous physicochemical stressors, and appropriate responses to these stresses at the cellular level are essential for the maintenance of homeostasis. The mitogen-activated protein Kinase (MAPK) cascades are having major signaling pathways in regulation of these cellular stress responses (Kazuki et al., 2009). The MAPK pathway consists of a cascade of three protein kinases. These protein kinases are sequentially activated, such as the MAPK kinase kinase (MAPKKK) phosphorylates and activates the MAPK kinase (MAPKK), which then phosphorylates and activates the MAPK. MAPKs have a wide variety of cellular functions, including proliferation, differentiation, migration and apoptosis. ASK1 identified as a member of the MAPKKK family and activate the MAPKK 4 (MKK4) JNK and MKK3/6-p38 pathways but not the MAP/ERK kinase (MEK)-extracellular signal-regulated kinase (ERK) pathway (Ichijo et al., 1997). Tumor necrosis factor-ÃŽ ± receptor-associated factors (TRAFs) having important role in the regulation of ASK1 activity. In TRAF family proteins, TRAF1, TRAF2, TRAF3, TRAF5 and TRAF6 are associate with ASK1, but only TRAF2, TRAF5 and TRAF6 increase ASK1 kinase activity (Nishitoh et al., 1998). TNF-ÃŽ ± treatment induces JNK activation in a TRAF2- dependent manner (Yeh et al., 1997, Tobiume et al., 2001). Phosphorylation of Thr845 in mouse ASK1 have role in activation of ASK1 (Tobiume et al., 2002). Endoplasmic reticulum (ER) stress activates ASK1 and involved in variety of neurodegenerative diseases (Lindholm et al., 2006). It has Pro-apoptotic role in mitochondrial membrane permeation. Decreased activation of ASK1/JNK by the antioxidant selenite correlated with neuroprotective effects (Wang et al., 2007). (6) Glycogen synthase kinase 3ÃŽ ² (GSK-3ÃŽ ²) Glycogen synthase kinase-3ÃŽ ² (GSK-3ÃŽ ²) is a constitutively active 47-kDa Ser/Thr protein kinase. It has about 40 substrates and having functions like cell proliferation, growth and death. GSK-3ß has a significant role in the regulation of apoptosis. Apoptotic injury is increased by the over-expression of GSK-3ß lead to cellular injury. During oxidative stress, GSK-3ß can lead to the activation of caspase 3 and cytochrome c release ultimately lead to apoptosis. Mechanism of GSK-3ÃŽ ² is phosphorylation at Ser and Tyr residues, complex formation with scaffold proteins, priming of substrates and intracellular translocation. GSK-3ÃŽ ² has been involved in serious diseases such as Alzheimers disease, bipolar mood disorder, cancer and ischemia/reperfusion injury (Tetsuji et al., 2009). It has Pro-apoptotic role in mitochondrial membrane permeation. Clinical dose of lithium inhibits GSK-3ÃŽ ² resulted in significant axon sprouting and functional recovery (Dill et al., 2008). (7) Protein kinase A (PKA) The protein kinase A (PKA) signaling pathway involves responses to hormonal stimulation which are often cell type specific.The PKA pathway involves the binding of an extracellular molecule to a G protein-coupled receptor, which catalyzes the formation of intracellular cyclic AMP through the activation of adenylate cyclase.Cyclic AMP then binds to the two regulatory subunits of PKA, thereby releasing the two catalytic subunits to phosphorylate serine and threonine residues on target proteins. These subunits enter the nucleus and phosphorylate transcription factors such as CREB and NF-ÃŽ ºB. PKA signaling in specific subcellular compartments has been recognized with the discovery of specific anchoring scaffold proteins. PKA activity has been identified within the mitochondria in a wide variety of species, including human (Kleitke et al., 1976). Mitochondrial targeted PKA activities have positive effects on the mitochondria. PKA localized to the inner membrane and matrix of mitochondria phosphorylates and promotes the activity of complex I (NADH dehydrogenase) (Technikova-Dobrova et al., 2001). AKAP (A-kinase anchoring proteins)-mediate the activation of PKA to the cytoplasmic surface of mitochondria results in phospho-inhibition of the proapoptotic protein BAD, enhancing cell survival (Harada et al., 1999, Affaitati et al., 2003). A peripheral benzodiazepine receptor-associated protein functions as an AKAP that promotes mitochondrial steroid genesis (Liu et al., 2003). AKAP-121 can also function as targeting of Mn-superoxide dismutase mRNA to the mitochondria for localized translation of this important antioxidant (Ginsberg et al., 2003).The small G-protein Rab32, which regulates mitochondrial fission, appears to function as a mitochondrially targeted AKAP(Alto et al., 2002). Thus, mitochondrial targeting of PKA appears to be involved in regulating most major mitochondrial functions, promoting respiration, antagonizing cell death, and regulating mitochondrial protein expression and biogenesis. (8) PTEN-induced kinase 1 (PINK1) PINK1 is a serine/threonine kinase having similarity to calcium/calmodulin regulated kinases. The primary sequence for PINK1 includes a canonical N-terminal mitochondrial leader sequence (Ruben K et al., 2009). PINK1 has been found in the mitochondria human brain and it is cleaved by matrix proteases. Transmembrane domain of PINK1 is responsible for its insertion in to outer mitochondrial membrane. The C-terminal domain of PINK1 having role of its auto phosphorylation (Liu et al., 2008). Point mutations and truncations of PINK 1 have been mapped throughout the transmembrane, kinase and C-terminal domains lead to impaired kinase activity and promote degradation, or induce misfolding of PINK1. The TNF receptor associated protein 1 (TRAP1, or Hsp75) are substrate for PINK1, and the serine protease Omi/Htra2 and heat shock proteins, Hsp90/Cdc37 are PINK1 binding proteins. So degradation of PINK1 catalytic activity leads to disease like parkinsonian neurodegeneration (DeFeo et al., 1981). 4 Human Diseases associated with Mitochondrial Kinases Mitochondria are important because of the Respiratory chain which is the major sites of energy production in all cells (Taylor et al., 2005). Mitochondria perform many functions in different tissues and cells so there are so many different mitochondrial diseases associated with different tissues of the body. Each disease produces abnormalities that are difficult to diagnose. There are complex relationship between the genes and cells that are responsible for maintaining our metabolic processes running smoothly; it is a basis of mitochondrial diseases. Mitochondrial diseases is due to degeneration of the mitochondria in specialized compartments present in every cell of the body except RBC (red blood cells).When mitochondria fail to generate energy, less energy is generated in the cell so cell injury and even cell death can occur. If this is repeated throughout the whole body, whole systems begin to fail, and the life of the person is severely compromised. The disease affects more in ch ildren as compared to adult but onset is becoming more and more common. Mitochondria diseases causes damage to cells of the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. Kinases that are associated with mitochondria during neuronal injury include mitogen activated protein kinases (MAPK) such as extracellular signal regulated protein kinases (ERK) and c-Jun N-terminal kinases (JNK), protein kinase B/Akt, and PTEN-induced kinase 1 (PINK1). Their sites of action within mitochondria and specific kinase targets are still unclear but these signaling pathways regulate mitochondrial respiration, transport, fission-fusion, calcium buffering, reactive oxygen species (ROS) production, mitochondrial autophagy and apoptotic cell death( Kachergus et al., 2005). 5 List of mitochondrial kinases associated human diseases: A) Neurodegenerative diseases: Parkinsons disease Alzheimers disease B) Cancer 1 Parkinsons disease (PD) Parkinsons disease is a debilitating, movement disorder that affects around 1 million people in North America. Symptoms: Motor symptoms can be due to degeneration of endogenously pigmented midbrain neurons of the nigrostriatal projection. Olfactory, autonomic and cognitive dysfunction. Most of the cases have no known cause; oxidative stress, disordered protein handling/degradation, and mitochondrial dysfunction are mechanistically observed factors in sporadic PD due to toxin/pesticide exposures, and in models of familial PD (Ruben et al., 2009). Factors like Disturbances in mitochondrial function, transport, dynamics and turnover have central role in neurotoxin, environmental and genetic approaches to Parkinsons disease (Ruben et al., 2009). In addition to changes in mitochondrial fission/fusion machinery and trafficking, autophagic degradation process has a critical role in regulating mitochondrial quality and content (Kiselyov et al., 2007). Macroautophagy has a role in membranous engulfment of cytoplasmic cargo bodies for lysosomal degradation, and this the major degradative pathway for organelles and insoluble proteins. There is deregulation of macroautophagy and of chaperone-mediated autophagy observed in toxin and genetic models of PD (Ruben et al., 2009). Gene multiplication and ÃŽ ±-synuclein mutations are autosomal dominant of PD in model of parkinsonian neurodegeneration (Polymeropoulos et al., 1997). Aggregation of ÃŽ ±-Synuclein, Lewy bodie formation and mutation in leucine rich repeat kinase 2 (LRRK2) are found in the sporadic and dominant forms of PD (Kachergus et al., 2005). Parkin, ATP13A2, DJ1 and PTEN induced kinase 1(PINK 1) are involved in autosomal recessive Parkinsonism disease. PINK1 and Parkin regulates mitochondrial morphology and turnover (Ruben et al., 2009). In human PD brain and diffuse Lewy body diseases, Phospho-ERK (p-ERK) in the cytoplasm and mitochondria of midbr

Income and Population Age Structure Essay -- Economics Income GNP Essa

Income and Population Age Structure A) Relationship between per capita GNP and population growth GNP is the value of all final goods and services produced in an economy over a period of one year. Thus per capita GNP is the division of value of goods and services available to each person in a country, i.e. it is the per head income in a country. And population growth is the rate, by which population grows in an economy. From the above drawn diagrams it can be said that the higher the population growth rate the lower the per capita GNP and vice versa. This is due to the fact that if the population increases at a faster rate the GNP will spread over a large number of people thus reducing the value of the Gross National Product per head. Similarly if the population grows at a slower rate the GNP is spread over fewer numbers of people thus increasing the value of the Gross National Product per head. To further illustrate this we can take into consideration countries like Jordan which has a relatively high population growth rate of a 4.9 and a per capita GNP of onl... Income and Population Age Structure Essay -- Economics Income GNP Essa Income and Population Age Structure A) Relationship between per capita GNP and population growth GNP is the value of all final goods and services produced in an economy over a period of one year. Thus per capita GNP is the division of value of goods and services available to each person in a country, i.e. it is the per head income in a country. And population growth is the rate, by which population grows in an economy. From the above drawn diagrams it can be said that the higher the population growth rate the lower the per capita GNP and vice versa. This is due to the fact that if the population increases at a faster rate the GNP will spread over a large number of people thus reducing the value of the Gross National Product per head. Similarly if the population grows at a slower rate the GNP is spread over fewer numbers of people thus increasing the value of the Gross National Product per head. To further illustrate this we can take into consideration countries like Jordan which has a relatively high population growth rate of a 4.9 and a per capita GNP of onl...

A Story by Li-Young Lee Poem AP Lang Prompt

The poem â€Å"A Story† written be Li- Young Lee conveys the complex father and son relationship showing their connection through literary devices while the son is trying to get his father to tell another story. This poem is written in third person narrative by an ominous voice telling the fathers thought process. The narrator begins the poem saying, â€Å"Sad is the man who is asked for a story and can’t come up with one. † This intro not only gives us a foreshadowing look onto the poem, but tells us the emotions the father feels given to us by the all knowing narrator.He tells us the dad is sad that he can’t think of a new story which shows us that he just want to please his son and in turn portraying love. The structure in this poem gives us a feeling of the old man’s desperation to dig up another story first portraying his uncomfort, â€Å"The man rubs his chin, scratches his ear. † His anxiousness escalates, â€Å"soon, he thinks, the b oy will give up on his father. † You see his attitude further rise when he says, â€Å"he sees the day this boy will go. Don’t go!†Finally you see his desperation reach a high when he says, â€Å"Are you a god, the man screams, that I sit mute before you? † The poem made you feel the desperation of the father through the structure because you could feel him getting more and more frustrated. This frustration in him not being able to satisfy his sons want for a new story gives us a picture of the love the father has for his child. A parent just wants to make their child happy and his anger when he cannot accomplish this show us that he has genuine love for the son.In the concluding paragraph the poet makes a comparison saying, â€Å"It is an emotional rather than logical equation, an earthly rather than heavenly one, which posits that a boy’s supplications and a father’s love add up to silence. † The contrast of the emotional and logical equations and the earthly and heavenly equations show us that this is not such a big deal after all. It is all in the fathers emotions. His love for his child is so great that he does not want to see him go.He is haunted by the day he thinks his son will leave him and he does not want to let his son down because he thinks that will make his son leave. This fear of letting his son down is preventing him from thinking of a new story. That is why the equation at the end is the sons request plus the father’s love equals silence. This relationship shown through the use of literary devices is a natural one showing the parents undying love for the child.

Digital PCS: The Future of Wireless Phone Service

In the past few years the use of mobile phones has increased tremendously. At one time only available to the rich and elite business executives, the luxury of mobile phones can now be used by a wide group of people in different financial situations. Mobile phones are a necessary convenience. They provide instant communication access wherever mobile phone service is offered. There are two options for mobile phone service: analog, and digital PCS. Analog is the more expensive option and has long been the standard for mobile phone service. Digital PCS is the newest form of phone service. It works by converting human speech into software codes and converting them to audio signals before the codes reach the listener. Because it is software based it provides a perfect platform for a variety of advanced wireless features. Digital PCS is the future of mobile phone service and the soon to be de facto standard for wireless phone service. People can choose digital PCS service for many reasons, though affordability might be the initial attraction. Because of competition by many companies price is always being driven down. Also, the many different customizable price plans offer an affordable package for any type of budget. Companies, which offer digital PCS service are always looking to lure new customers, and therefore are in constant review of their plans always trying to make sure they are treating their customers properly. This eventually leads to the best product for the customer. If there is any drawback to digital PCS it is that the service is still fairly new. Digital PCS systems need to be laid from the ground up. They are physically hard-wired from community to community. While designing a system like this takes much longer, the outcome is worth it. Hard-wired systems provide for a stronger signal, and better connection. Because the implementation of the system takes long, it is difficult to spread digital PCS service quickly. But the service is expanding rapidly and soon, it will cover most of the country. Another drawback is that people cannot use Digital PCS phones in the more common analog environments. Much of the country is already equipped with analog services so it is better to purchase a dual band Digital PCS service phone that has analog service on it also. While these dual band phones are expensive, they provide connections in both analog and digital environments. Since digital PCS is based on wireless software it allows a robust variety of applications to be used with the service. This allows your phone to expand its capabilities. These applications enable you to be reached at all times. Phones using digital PCS service include caller ID, voice mail, paging, enhanced battery management, and encryption systems. These applications make the phone a powerful communication system. Caller ID is a feature that alerts you to what number is calling. When your phone rings the display units flashes the incoming number of the caller. On some phones you can program the name with the number, so the next time that number calls the name flashes along with the incoming number. This feature is useful since the owner can preview who is calling the phone before he even takes the call. People can evaluate the importance of the call and see if their time is important enough for the person who is calling them. Another feature that makes digital PCS superior is interactive voice mail. Interactive voice mail is a voice mail system that alerts you when voice messages are received. Traditional voice mail systems require the owner to keep calling in order to check if new messages are on the system. On a digital PCS system, when the person receives a voice mail, a signal is sent to the phone and the phone alerts the owner of the new mail. This method prevents the waste of unnecessary airtime or personal time checking the voice mail. Digital PCS phones are always in signal contact with the service provider. When the phone is turned on, a signal is always sending information to and from the phone. The signal indicates to the phone how to regulate power. This leads to a longer battery life since the phone can â€Å"sleep† when peak energy is not needed. Battery information is always reported on the display unit, thus allowing the owner to know well ahead when the battery is about to go weak. This allows the owner of the phone to know whether or not to charge the phone or carry a new battery. Digital PCS sends signals in ISO-3 digital format. This means that calls made from a digital PCS phone are encrypted and cannot be scanned or eavesdropped on. Digital voice transmission enables you to feel confident when discussing personal information over your digital PCS phone. Since many people use mobile phones, to conduct business this element is crucial to their goal of protecting sensitive information Alphanumeric paging is one of the best features of digital PCS service. This paging allows someone to send a page with regular text. Also it enables you to receive specially formatted Internet information, such as news and stock quotes. Also having alphanumeric paging allows someone to email the phone, and depending on the phone, a response can also be sent. This feature provides access to electronic mail when one is not near a computer. E-mail has become very important for many people, so having access to email is very essential. This feature also eliminates having to carry a separate pager for your alphanumeric paging needs. Digital phones are the future. They provide services that analog mobile phones could never provide. From an engineering standpoint alone, phones using digital PCS are more advanced and capable of amazing applications. But it is the convenience that digital PCS phones provide which make them a better option for people who are on the move. From a system level, they are designed from the ground up, providing the best connection and signal performance. Digital PCS is software based thus providing better applications such as caller ID, voice mail, enhanced battery management, paging, and encryption systems. They save time by providing on demand information including alerting the owner immediately when a voice mail is received, and when the battery of the phone will expire. They are affordable in cost because many companies are in competition to provide the best service. This provides the customer with ample choices to evaluate. Digital PCS phone service is reliable, robust and affordable. It allows a person to be able to be reached at all times. It is the future and the soon to be standard for wireless communications. Digital PCS, the future of mobile phones is here.