In healthcare settings, the importance of effective management cannot be overstated. It plays a pivotal role in guaranteeing the provision of top-notch care, maximizing resource utilization, and enhancing patient outcomes. This article aims to offer a comprehensive overview of management strategies employed in healthcare organizations, encompassing both clinical and non-clinical aspects. By delving into the roles and responsibilities of healthcare managers, examining clinical management techniques, and emphasizing the significance of non-clinical management practices, we shed light on the criticality of integrating both approaches with the aim of attaining optimal healthcare outcomes through a harmonious blend of clinical and non-clinical management methodologies.
Background: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of hyperphosphorylated tau (p-tau) in neurofibrillary tangles and beta-amyloid plaques. The role of oxidative stress (OS) in AD progression remains unclear. Methods: Using SH-SY5Y human neuroblastoma cells as an in vitro model, we investigated the impact of OS on tau phosphorylation. Mature neurons were exposed to varying concentrations of hydrogen peroxide for different durations (1-5 days) to simulate OS. Western blot analysis was employed to quantify key signalling pathways (LKB1, AMPK, and Akt) and antioxidant enzymes (SOD2, p1, p4, and catalase). Results: Prolonged OS exposure resulted in tau hyperphosphorylation at Ser262, a tau residue sensitive to AMPK, despite initial dephosphorylation. Treatment with compound C (CC), an AMPK inhibitor, prevented this effect. OS activated LKB1 and AMPK, enhanced by CC and rapamycin, while CC and rapamycin suppressed OS-induced Akt activity. SOD2, the primary defence against OS, increased, whereas p1 and catalase, the secondary defence, decreased. P4 activity remained unchanged. Notably, CC consistently reduced antioxidant enzyme activity across experimental groups. Conclusion: OS activates the LKB1, AMPK, and Akt signalling pathways. The interplay between LKB1's stimulatory effect and Akt's inhibitory effect on AMPK leads to AMPK activation and subsequent tau hyperphosphorylation. AMPK facilitates the protective response mediated by SOD2 against OS, but prolonged OS exposure induces tau hyperphosphorylation. Therefore, OS likely serves as a trigger for AD pathology.
Alzheimer’s disease (AD) and cancer are among the leading causes of human death around the world. While neurodegeneration is the main feature of AD, the most important characteristic of malignant tumors is cell proliferation, placing these two diseases in opposite sides of cell division spectrum. Interestingly, AD and cancer’s pathologies consist of a remarkable common feature and that is the presence of active cell cycle in both conditions. In an in vitro model of primary adult neuronal culture, we previously showed that treating cell with beta amyloid forced neurons to start a cell cycle. Instead of cell division, however, neuronal cell cycle was aborted and a massive neurodegeneration was left behind as the consequence. A high level of cell cycle entry, which is a requirement for cancer pathogenesis, was reported in clinically diagnosed cases of AD, leading to neurodegeneration. The diverse clinical manifestation of a similar etiology, have puzzled researchers for many years. In fact, the evidence showed an inverse association between AD and cancer prevalence, suggesting that switching pathogenesis toward AD protects patients against cancer and vice versa. In this mini review, we discussed the possibility of involvement of cell proliferation and survival dysregulation as the underlying mechanism of neurodegeneration in AD, and the leading event to develop both disorders’ pathology. As examples, the role of phosphoinositide 3 kinase/Akt/ mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway in cell cycle re-entry and blocking autophagy are discussed as potential common intracellular components between AD and cancer pathogenesis, with diverse clinical diagnosis.
BACKGROUND Alzheimer's disease (AD) pathology consists of intraneuronal neurofibrillary tangles, made of hyperphosphorylated tau and extracellular accumulation of beta amyloid (Aβ) in Aβ plaques. There is an extensive debate as to which pathology initiates and is responsible for cellular loss in AD. METHODS Using confocal and light microscopy, post mortem brains from control and AD cases, an antibody to SOD2 as a marker for mitochondria and an antibody to all forms of tau, we analyzed mitochondrial density in tau positive neurons along with nuclear degradation by calculating the raw integrative density. RESULTS Our findings showed an extensive staining of aggregated tau in cell bodies, dystrophic neurites and neurofilaments in AD with minimal staining in control tissue, along with a marked decrease in mitochondria in tau positive (tau+) neurons. The control or tau negative (tau-) neurons in AD contained an even distribution of mitochondria, which was greatly diminished in tau+ neurons by 40%. There were no significant differences between control and tau- neurons in AD. Tau+ neurons showed marked nuclear degradation which appeared to progress with the extent of tau aggregation. The aggregated tau infiltrated and appeared to break the nuclear envelope with progressively more DNA exiting the nucleus and associating with the aggregated intracellular tau. CONCLUSION We report that the mitochondrial decrease is likely due to a decrease in the protein synthesis rather than a redistribution of mitochondria because of the decreased axonal transport. We suggest that the decrease in mitochondria and nuclear degradation are key mechanisms for the neuronal loss seen in AD.
Background Cellular energy failure in high metabolic rate organs is one of the underlying causes for many disorders such as neurodegenerative diseases, cardiomyopathies, liver and renal failures. In the past decade, numerous studies have discovered the cellular axis of LKB1/AMPK/mTOR as an essential modulator of cell homeostasis in response to energy stress. Through regulating adaptive mechanisms, this axis adjusts the energy availability to its demand by a systematized control on metabolism. Energy stress, however, could be sensed at different levels in various tissues, leading to applying different strategies in response to hypoxic insults. Methods Here the immediate strategies of high metabolic rate organs to time-dependent short episodes of ischaemia were studied by using a rat model ( n = 6/group) of cardiac arrest (CA) (15 and 30 s, 1, 2, 4 and 8 min CA). Using western blot analysis, we examined the responses of LKB1/AMPK/mTOR pathway in brain, heart, liver and kidney from 15 s up to 8 min of global ischaemia. The ratio of ADP/ATP was assessed in all ischemic and control groups, using ApoSENSOR bioluminescent assay kit. Results Brain, followed by kidney showed the early dephosphorylation response in AMPK (Thr 172 ) and LKB1 (Ser 431 ); in the absence of ATP decline (ADP/ATP elevation). Dephosphorylation of AMPK was followed by rephosphorylation and hyperphosphorylation, which was associated with a significant ATP decline. While heart’s activity of AMPK and LKB1 remained at the same level during short episodes of ischaemia, liver’s LKB1 was dephosphorylated after 2 min. AMPK response to ischaemia in liver was mainly based on an early alternative and a late constant hyperphosphorylation. No significant changes was observed in mTOR activity in all groups. Conclusion Together our results suggest that early AMPK dephosphorylation followed by late hyperphosphorylation is the strategy of brain and kidney in response to ischaemia. While the liver seemed to get benefit of its AMPK system in early ischameia, possibly to stabilize ATP, the level of LKB1/AMPK activity in heart remained unchanged in short ischaemic episodes up to 8 min. Further researches must be conducted to elucidate the molecular mechanism underlying LKB1/AMPK response to oxygen supply.
The overwhelming majority of dominant mutations causing early onset familial Alzheimer's disease (EOfAD) occur in only three genes, PSEN1, PSEN2, and APP. An effect-in-common of these mutations is alteration of production of the APP-derived peptide, amyloid β (Aβ). It is this key fact that underlies the authority of the Amyloid Hypothesis that has informed Alzheimer's disease research for over two decades. Any challenge to this authority must offer an alternative explanation for the relationship between the PSEN genes and APP. In this paper, we explore one possible alternative relationship - the dysregulation of cellular iron homeostasis as a common effect of EOfAD mutations in these genes. This idea is attractive since it provides clear connections between EOfAD mutations and major characteristics of Alzheimer's disease such as dysfunctional mitochondria, vascular risk factors/hypoxia, energy metabolism, and inflammation. We combine our ideas with observations by others to describe a "Stress Threshold Change of State" model of Alzheimer's disease that may begin to explain the existence of both EOfAD and late onset sporadic (LOsAD) forms of the disease. Directing research to investigate the role of dysregulation of iron homeostasis in EOfAD may be a profitable way forward in our struggle to understand this form of dementia.
Aggregation of hyperphosphorylated tau (p-tau) in the form of neurofibrillary tangles (NFT) is a main hallmark for Alzheimer's disease (AD). Activation of cellular metabolic axis, made of adenosine monophosphate kinase protein kinase (AMPK) and mammalian target of rapamycin (mTOR) have been implicated in generating tau pathology of AD. Thus, blocking either of these two proteins or both, are suggested as the future therapeutic approaches for AD. How and to what level these approaches could be applied, however are not entirely clear. By using Compound C (CC) in this study, we showed a substantial decrease in mTOR activity in a rapamycin-independent way without blocking AMPK. This decline in mTOR activity was accompanied by an increase in phosphoinositide 3 kinase (PI3K)/Akt activity and a parallel increase in p-tau (Ser(396) ) but not p-tau (Ser(262) ) in differentiated SH-SY5Y neuroblastoma cells. This elevation was blocked when the cells were treated with 15 mu M of LY294002, a specific PI3K inhibitor, suggesting PI3K involvement in CC-mediated tau hyperphosphorylation at Ser(396). For all groups the activity levels of glycogen synthase kinase-3 beta (GSK-3 beta), cyclin-dependent kinase-5 (cdk5) and protein phosphatase 2A (PP2A), the other main kinases and phosphatase responsible for tau phosphorylation/dephosphorylation remained unchanged. Collectively, our results demonstrate that rapamycin-independent blocking of mTOR enhances p-tau (Ser(396)) in a PI3K-dependent way, suggesting the careful consideration of future therapeutic approaches for AD, which will be based on mTOR inhibition.
Hyperphosphorylation of tau is one of the main hallmarks for Alzheimer's disease (AD) and many other tauopathies. Norepinephrine (NE), a stress-related hormone and 17-β-estradiol (E2) thought to influence tau phosphorylation (p-tau) and AD pathology. The controversy around the impact of NE and E2 requires further clarification. Moreover, the combination effect of physiological and psychological stress and estrogen alteration during menopause, which affect p-tau, has not been addressed. Exposure to E2 is believed to reduce NE release, however, the link between these two hormones and AD at cellular level was also remained unknown. Here, we examined whether NE and E2 treatment of differentiated SH-SY5Y cells affected tau phosphorylation. The involvement of adenosine monophosphate kinase protein kinase (AMPK) and target of Rapamycin (mTOR) as the possible mechanisms, underlying this effect was also investigated. Subsequent to SH-SY5Y differentiation to mature neurons, we treated the cells with NE, E2 and NE plus E2 in presence and absence of Compound C and Rapamycin. Cell viability was not affected by our treatment while our Western blot and immunofluorescent findings showed that exposure to NE and E2 separately, and in combination enhanced p-tau (Ser396) and (Ser262)/tau but not (Ser202/Thr205)/tau. Blocking AMPK by Compound C reduced p-tau (Ser396) and (Ser262), while GSK-3β and PP2A activities were remained unchanged. We also found that blocking mTOR by Rapamycin did not change increased p-tau (Ser396) and (Ser262) due to NE + E2 treatment. Collectively, our results suggested that tau hyperphosphorylation due to exposure to NE/E2 was mediated by AMPK, the main energy regulator of cells during stress with no significant involvement of mTOR, GSK-3β and PP2A.
BACKGROUND:Emerging evidence supports the hypothesis that metabolism dysfunction is involved in pathogenesis of Alzheimer's disease (AD). One aspect of metabolic dysfunction includes dysregulation of adenosine monophosphate kinase protein kinase (AMPK) and mammalian target of rapamycin (mTOR) metabolic axis, which is extensively present in some of the leading causes of AD such as cerebrovascular diseases, type 2 diabetes and brain ischaemic events. While the molecular basis underlying this metabolic dysregulation remains a significant challenge, mitochondrial dysfunction due to aging appears to be an essential factor to activate AMPK/mTOR signaling pathway, leading to abnormal neuronal energy metabolism and AD pathology.METHODS:Using immunofluorescent imaging by Lecia confocal microscopy, we analyzed the activation of AMPK/mTOR. Concurrently, the level of mitochondrial antioxidant enzymes of superoxide dismutase 2 (SOD2) and peroxiredoxin 1 and 4 (p1 and p4) along with protein and DANA oxidation were examined to in postmortem brains of AD (n= 8) and normal (n= 7) subjects to evaluate the metabolism dysfunction role in AD pathology.RESULTS:In spite of AMPK inhibitory control on mTOR, concurrent phosphorylation of AMPK and mTOR (p-AMPK and p-mTOR) was observed in AD brains with high colocalization with hyperphosphorylated tau. Mitochondrial antioxidant enzymes of SOD2 and p1 and p4 were substantially decreased in p-AMPK, p-mTOR and p-tau positive cells along with higher levels of DNA and protein oxidation.CONCLUSION:Collectively, we conclude that AMPK and mTOR metabolic axis is highly activated in AD brains. While the inhibitory link between AMPK and mTOR seems to be disrupted, we suggest oxidative stress as the underlying mechanism for concurrent activation of AMPK and mTOR in AD.
Objective: Brain ischemia is a consequence of stroke and cardiac arrest (CA), leading to short and long-term neurological impact involving cognitive function as well as dementia. An accurate, simple and reproducible model of CA ischemia and reperfusion is valuable in assessing the response to ischemia and therapeutic interventions. In the current study the effectiveness of a reversible model of CA has been assessed through examining the brain response in expressing tau and hyperphosphorylated tau (p-tau) protein, one of the main hallmarks of Alzheimer’s disease. Method: In the current study we used a two phase alternating current (AC)-derived reversible CA to generate global-brain ischemia through ventricular fibrillation (VF)/ventricular standstill followed by defibrillation, mechanical ventilation and standard resuscitation in 26 female adult Sprague Dawley rats. This model mimics CA in humans and allows testing of experimental interventions to restore/ preserve brain function. Two phases of AC (24 Volts (V) followed by 18 V) were applied through a two-ring oesophageal wire. After 2-, 4and 8-minute CA, resuscitation was initiated by ventilation, 8 Joules (J) chest electrical shock in the event of VF, adrenaline injection and manual chest compression. ECG, pulse rate and blood oxygen saturation were recorded during the resuscitation. Tau and p-tau levels were assessed as an indicator of neuronal response to ischemia. Results: Resuscitation outcomes were assessed at 1st and 2nd hour and 4th week of restoration of blood circulation and animal survival. We report an early tau dephosphorylation which was followed by hyperphosphorylation after 4 weeks, while the total tau remained unchanged. Conclusions: This method successfully produced reproducible global brain ischemia generating tau dephosphorylation in shortterm recovery and hyperphosphorylation in long-term recovery. The findings show the efficiency of this technique in providing a tool to study the further neuronal response to ischemic situations and the underlying mechanisms.
Abnormal tau phosphorylation (p-tau) has been shown after hypoxic damage to the brain associated with traumatic brain injury and stroke. As the level of p-tau is controlled by Glycogen Synthase Kinase (GSK)-3, Protein Phosphatase 2A (PP2A) and Adenosine Monophosphate Kinase (AMPK), different activity levels of these enzymes could be involved in tau phosphorylation following ischaemia. This study assessed the effects of global brain ischaemia/reperfusion on the immediate status of p-tau in a rat model of cardiac arrest (CA) followed by cardiopulmonary resuscitation (CPR). We reported an early dephosphorylation of tau at its AMPK sensitive residues, Ser(396) and Ser(262)after 2min of ischaemia, which did not recover during the first two hours of reperfusion, while the tau phosphorylation at GSK-3 sensitive but AMPK insensitive residues, Ser(202)/Thr(205) (AT8), as well as the total amount of tau remained unchanged. Our data showed no alteration in the activities of GSK-3 and PP2A during similar episodes of ischaemia of up to 8min and reperfusion of up to 2h, and 4weeks recovery. Dephosphorylation of AMPK followed the same pattern as tau dephosphorylation during ischaemia/reperfusion. Catalase, another AMPK downstream substrate also showed a similar pattern of decline to p-AMPK, in ischaemic/reperfusion groups. This suggests the involvement of AMPK in changing the p-tau levels, indicating that tau dephosphorylation following ischaemia is not dependent on GSK-3 or PP2A activity, but is associated with AMPK dephosphorylation. We propose that a reduction in AMPK activity is a possible early mechanism responsible for tau dephosphorylation.
An increase in phosphorylated tau (p-tau) is associated with Alzheimer's disease (AD), and brain hypoxia. Investigation of the association of residue-specific tau hyperphosphorylation and changes in cognition, leads to greater understanding of its potential role in the pathology of memory impairment. The aims of this study are to investigate the involvement of the main metabolic kinases, Liver Kinase B1 (LKB1) and Adenosine Monophosphate Kinase Protein Kinase (AMPK), in tau phosphorylation-derived memory impairment, and to study the potential contribution of the other tau kinases and phosphatases including Glycogen Synthase Kinase (GSK-3β), Protein kinase A (PKA) and Protein Phosphatase 2A (PP2A). Spatial memory and learning were tested in a rat global brain ischemic model of reversible cardiac arrest (CA). The phosphorylation levels of LKB1, AMPK, GSK-3β, PP2A, PKA and tau-specific phosphorylation were assessed in rats, subjected to ischaemia/reperfusion and in clinically diagnosed AD and normal human brains. LKB1 and AMPK phosphorylation increased 4 weeks after CA as did AMPK related p-tau (Ser262). The animals showed unchanged levels of GSK-3β specific p-tau (Ser202/Thr205), phospho-PP2A (Tyr307), total GSK-3β, PP2A, phospho-cAMP response element-binding protein (CREB) which is an indicator of PKA activity, and no memory deficits. AD brains had hyperphosphorylated tau in all the residues of Ser262, Ser202 and Thr205, with increased phosphorylation of both AMPK (Thr172) and GSK-3β (Ser9), and reduced PP2A levels. Our data suggests a crucial role for a combined activation of tau kinases and phosphatases in adversely affecting memory and that hyperphosphorylation of tau in more than one specific site may be required to create memory deficits.
Accumulation of protein aggregates is the leading cause of cellular dysfunction in neurodegenerative disorders. Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease, Prion disease and motor disorders such as amyotrophic lateral sclerosis, present with a similar pattern of progressive neuronal death, nervous system deterioration and cognitive impairment. The common characteristic is an unusual misfolding of proteins which is believed to cause protein deposition and trigger degenerative signals in the neurons. A similar clinical presentation seen in many neurodegenerative disorders suggests the possibility of shared neuronal responses in different disorders. Despite the difference in core elements of deposits in each neurodegenerative disorder, the cascade of neuronal reactions such as activation of glycogen synthase kinase-3 beta, mitogen-activated protein kinases, cell cycle re-entry and oxidative stress leading to a progressive neurodegeneration are surprisingly similar. This review focuses on protein toxicity in two neurodegenerative diseases, AD and PD. We reviewed the activated mechanisms of neurotoxicity in response to misfolded beta-amyloid and α-synuclein, two major toxic proteins in AD and PD, leading to neuronal apoptosis. The interaction between the proteins in producing an overlapping pathological pattern will be also discussed.