Sajjad, et al.: Pathogenesis of Alzheimer's DiseaseThe pathological emblems of Alzheimer's disease are the accumulation of amyloid-β plaques and neurofibrillary tangles. The alluvium of toxic amyloid-β-protein in the form of aggregates is central to the pathogenesis of Alzheimer's disease. The aggregate formation is due to the structural refitting of α-helical sheet of normal, soluble amyloid-β-protein to the β-sheets, which lead to oligomeric, fibrillar, insoluble and disease causing amyloid-β 42. Mounting data suggests that another factor, the tau protein ripens into highly phosphorylated form by several kinases after Aβ-stimulation leads to tangle formation resulting in neuronal bereavement in hippocampus and entorhinal regions as the disease progresses further. An overview has been presented in this review of the role of tau as an important partner of amyloid-β in the pathogenesis of Alzheimer's disease, both of which could be used as biomarkers for diagnosis and risk assessment with other molecular chaperones, which are associated with Alzheimer's disease. As a part of common pathophysiological mechanism the understanding of amyloid-β and tau toxicities might be helpful for finding molecular targets for the prevention or even cure of Alzheimer's disease.

Low frequency oscillation (LFO) within a power system is an important issue. Loss of inter-connected machine synchronism, reactive load increase, and faults and disturbances lead to a LFO in a range between 0.1-2 Hz. LFOs limit power transfer over long transmission lines, thus degrading the quality of supply. Moreover, conventional local control, namely, the power system stabilizer, is unable to mitigate LFOs. Furthermore, continuation of LFOs will lead to complete system collapse (blackouts). Considering the above issues, there is a pressing need to incorporate advanced control systems to damp inter-area LFOs. We propose an adaptive-supplementary unified power flow control (UPFC) for two inter-connected areas of a power system. Our work is novel in its design of a supplementary control system using a neural network based on a feedback linearization auto-regression average model. With the above proposed control scheme, the stability of power system is enhanced in terms of: (1) effective LFO damping; (2) power transfer; (3) improvement in the dynamic parameters of the system; (4) active and reactive power support; (5) loss minimization; and (6) demand-supply management. To justify these claims, we implement our proposed controller on a two-area (four machine) system. Critical analysis of the system is conducted under symmetrical grid faults. The result of the proposed control scheme justifies the performance enhancement of above parameters, as per grid-code requirements, compared with conventional a proportional integral (PI) controller.

Objective: To determine important errors in initial Gram staining of clinical specimens and evaluate the types of Gram-stain errors. Study Design: Cross-sectional study. Place and Duration of Study: Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi Pakistan, from Aug 2018 to Feb 2019. Methodology: Gram staining and culture inoculation of all specimens were performed per recommended guidelines. The Gram stain results on day-0 were compared with the results of the culture on day-2. There was no discrepancy if similar organisms were obtained on culture as on Gram stain. Nevertheless, if the Gram stain and culture results were not similar, it was termed a discrepancy. The consultant microbiologist reviewed all discrepant slides, and if not resolved, possible causes of error were sought, and the results documented. Results: Of the total 300 clinical specimens, errors were observed in the initial gram staining of 29 specimens (9.7%), whereas 271(90.3%) specimens were error-free. Upon evaluating these 29 errors, 11(38.0%) were observer errors which were resolved when reviewed by a consultant microbiologist. 14(48.0%) were technical errors, and 4(14.0%) results were discrepant due to the presence of anaerobic organisms, missed on initial aerobic cultures. Conclusion: The frequency of Gram stain errors in our study (9.7%) is not very high; nevertheless, it can have severe consequences in critical samples from seriously ill patients if wrong empirical antimicrobial treatment is begun based on a wrong initial Gram stain result.

Placenta accrete spectrum (PAS) previously known as morbid adherent placenta, is a complex obstetric complication that has risen exponentially in the last couple of decades. It carries serious fetomaternal risk in terms of morbidity and mortality, also increasing perinatal mortality owing to prematurity. PAS include three variants depending upon the degree of placental penetration, i.e. accrete, increta and percreta. We highlighted the unique diagnostic criteria of the placenta accrete spectrum,which includes the history of incomplete removal of the placenta, with repeated evacuation, persistent vaginal bleeding and ultrasound evidence of retained products of conception.