Minireview: Bacterial Persistence Mechanisms to Escape Antibiotic Effects

قدرة البكتيريا على الإحساس والاستجابة لما حولها تمكننها من البقاء والنمو في ظل أنواع مختلفة من ظروف الاجهاد. المقاومة والتسامح والمثابرة هي استراتيجيات البقاء التي تمتلكها البكتيريا للتغلب على البيئات المجهدة. يُعزى فشل العلاجات بالمضادات الحيوية إلى استراتيجيات الدفاع هذه. يمكن أن يؤدي التصنيف الخاطئ لهذه الأنماط الظاهرية الثلاثة, نتيجتا لسوء التوصيف, إلى عدم فعالية العلاجات. على عكس المقاومة ، التي تنتج عن تطورات أو طفرات واكتساب جينات المقاومة الخارجية ، والتي تسمح للبكتيريا بالتكاثر تحت المضادات الحيوية، تسمح المثابرة لمجموعة سكانية فرعية من البكتيريا الحساسة بالهروب من إجهاد المضادات الحيوية عن طريق الدخول الى حالة السبات الغير تكاثرية. تم الإبلاغ عن العديد من الآليات الجزيئية ذات العلاقة بظاهرة المثابرة  ضد المضادات الحيوية في البكتيريا. أهم آليتين للمثابرة والثباتية في البكتيريا هما نظام السموم و ضد السموم والاستجابة الصارمة. تلخص هذه المقالة دور بعض الاليات الجزيئية (الاستجابة الصارمة، استجابة  SOS، استقلاب الفوسفات، عامل سيغما، نظام السم وضد السم) في المثابرة البكتيريةThe ability of bacteria to sense and respond to their surrounding allows them to survive and grow under different types of stressful conditions. Resistance, tolerance, and persistence are survival strategies Bacteria possess to overcome stressful environment. The failure of Antibiotic treatments is attributed to these defense strategies. The misclassification of these three phenotypes as a result of poor characterization can result in treatments ineffectiveness.  Unlike resistance, which is resulted from evolutions or mutations and external resistant genes acquisitions, that allows bacteria to reproduce under antibiotics, persistence allows a subpopulation of susceptible bacteria to escape antibiotic stress by entering a dormant non-replicative state. Several molecular mechanisms have been reported to implicate bacterial persistence to antibiotics. The two most substantial mechanisms of persistence in bacteria are Toxin- antitoxin system and stringent response. This review summarizes the role of some molecular mechanisms (Stringent response, SOS response, Phosphate metabolism, Sigma factor, and Toxin- antitoxin system) in bacterial persistence

The Impact of Social Media Attributes on Purchase Intention in the Saudi Foodservice

This study aims to investigate the impact of social media attributes on customer purchase intention in the Saudi foodservice.  It is a quantitative study based on the use of a questionnaire designed to fulfill the key purpose of this study. A judgmental sampling strategy is used to select the participants due to the wide population size. 380 questionnaires were collected and 357 were analyzed. SPSS.26 was used to analyze the data and to test the study hypotheses. The findings of this study revealed that social media attributes (perceived usefulness, perceived ease of use, critical mass and perceived playfulness) have has a positive impact on purchase intention. Keywords: Purchase Intention, Foodservice, Social Media Attributes, Saudi Arabia JEL Classifications: M40; M41 DOI: https://doi.org/10.32479/irmm.971

Smart Operations of Air-Conditioning and Lighting Systems in a Government Buildings for Peak Power Reduction

This paper presents the achievements of implementing smart operations strategies for air-conditioning (A/C) and lighting systems in Justice Palace Complex (JPC), Kuwait during the summer 2007. The peak load of this building was 3700 kW. The achievements are summarized as direct savings between 13:00 and 22:00 h by closing supply and return air fans of 52 air-handling units with a connected load 400 kW, and an additional saving of 550 kW during the same period by optimizing the cooling production and distribution. Also an all time saving of 22 kW by de-lamping, and additional saving of 27 kW through TDC of lighting were achieved. In conclusion project achieved an overall reduction in power demand of around 20% between 13:00 to 17:00 h and reduction ranging from 7% to 15% between 17:00 to 20:00 h

Demand-side management in office buildings in Kuwait through an ice-storage assisted HVAC system with model predictive control

Examining methods for controlling the electricity demand in Kuwait was the main objective and motivation of this researchp roject. The extensiveu se of air-conditioning for indoor cooling in office and large commercial buildings in Kuwait and the Gulf States represents a major part of the power and electricity consumption in such countries. The rising electricity generation cost and growing rates of consumption continuously demand the construction new power plants. Devising and enforcing Demand-SideM anagemen(t DSM) in the form of energye fficient operations trategies was the response of this research project to provide a means to rectify this situation using the demand-side management technique known as demand levelling or load shifting. State of the art demand-sidem anagementte chniquesh ave been examined through the developmenot f a model basedp redictive control optimisations trategyf or an integrateda ndm odulara pproachto the provisiono f ice thermals torage. To evaluate the potential of ice-storage assisted air-conditioning systems in flattening the demand curve at peak times during the summer months in Kuwait, a model of a Heating, Ventilation, and Air-conditioning (HVAC) plant was developed in Matlab. The model engaged the use of model based predictive control (MPQ) as an optimisation tool for the plant as a whole. The model with MPC was developed to chose and decide on which control strategy to operate the integrated ice-storage HVAC plant. The model succeeded in optimising the operation of the plant and introduced encouraging improvement of the performance of the system as a whole. The concept of the modular ice-storage system was introduced through a control zoning strategy based on zonal orientation. It is believed that such strategy could lead to the modularisation of ice-storage systems. Additionally, the model was examined and tested in relation to load flattening and demonstrated promising enhancement in the shape of the load curve and demonstrated flattened demand curves through the employed strategy. When compared with measured data from existing buildings, the model showed potential for the techniques utilised to improve the load factor for office buildings.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Application of Randomly Amplified Polymorphic DNA (RAPD) Technique to Estimate Genetic Distance among Some Methicillin Resistant Staphylococcus aureus Isolated from Different Iraqi Hospitals

Methicillin resistant Staphylococcus aureus (MRSA) is one of the principal nosocomial causative agents. This bacterium has the capability to resist wide range of antibiotics and it is responsible for many diseases like skin, nose and wounds infection. In this study, randomly amplified polymorphic DNA (RAPD)-PCR was applied with ten random primers to examine the molecular diversity among methicillin resistant Staphylococcus aureus (MRSA) isolates in the hospitals and to investigate the genetic distance between them. 90 Isolates were collected from clinical specimens from Iraqi hospitals for a total of 90 isolates. Only 10 strains (11.11%) were found to be MRSA. From these 10 primers, only 9 gave clear amplification products. 91 fragment lines were generated from these primers across all isolates with an average of 10 fragment lines per primer. Of these, 90 (99%) were polymorphic. The size of the amplified bands ranged between 145-2109 bp. The polymorphism percentage for all primers was 100% except OP-X17 primer which gave 86% polymorphism. The genetic distances revealed from Jaccard similarity index was calculated for the 90 RAPD polymorphic fragment lines. The highest genetic distance value 0.959 was between isolate number (1) and (5) and between isolate number (3) and (10), while the lowest genetic distance value 0.218 was between isolate number (6) and (7). This study shows that RAPD-PCR technique assayed with nine primers can be successfully applied to reveal the genetic distances among methicillin resistant Staphylococcus aureus (MRSA) isolates from different hospitals

Improving the Water Efficiency of Cooling Production System

For most of the time, cooling towers (CTs) of cooling systems operate under partial load conditions and by regulating the air circulation with a variable frequency drive (VFD), significant reduction in the fan power can be achieved. In Kuwait and other counties of Arabian Peninsula, reduced airflow can lead to reduction in water consumption as well, since during the summer season, the dry bulb temperature of the ambient air is higher than the incoming hot water temperature, and the air undergoes sensible cooling. This paper presents the findings of a study conducted in the Avenues mall, Kuwait. Initially, the CTs operated only at high speed, and on a typical summer day nearly one fourth of the make-up water was used for self cooling of air. The study based on measured data revealed that the use of VFD can reduce the water wastage for self-cooling of air by as much as 75% and overall water consumption by 18.6% while keeping the cooling system performance at design level

Smart Operations of Air-Conditioning and Lighting Systems in a Government Buildings for Peak Power Reduction

This paper presents the achievements of implementing smart operations strategies for air-conditioning (A/C) and lighting systems in Justice Palace Complex (JPC), Kuwait during the summer 2007. The peak load of this building was 3700 kW. The achievements are summarized as direct savings between 13:00 and 22:00 h by closing supply and return air fans of 52 air-handling units with a connected load 400 kW, and an additional saving of 550 kW during the same period by optimizing the cooling production and distribution. Also an all time saving of 22 kW by de-lamping, and additional saving of 27 kW through TDC of lighting were achieved. In conclusion project achieved an overall reduction in power demand of around 20% between 13:00 to 17:00 h and reduction ranging from 7% to 15% between 17:00 to 20:00 h

Smart Operations of Air-Conditioning and Lighting Systems in Government Buildings for Peak Power Reduction

During the summer 2007 smart operation strategies for air-conditioning (A/C) and lighting systems were developed and tested in a number of governmental buildings in Kuwait as one of the solutions to reduce the national peak demand for electrical power that commonly occur around 15:00 h. The working hours for these building are generally between 07:00 and 14:00 h and their peak demand exceeds 600 MW. The smart operation strategies implemented in these buildings included pre-closing treatment (PCT) between 13:00 and 14:00 h and time-of-day control (TDC) after 14:00 h. Also de-lamping was carried out in some of the buildings to readjust the higher than recommended illumination levels. This paper presents the achievements of implementing these smart operations strategies in Justice Palace Complex (JPC) as a case study. The peak load of this building was 3700 kW. The achievements are summarized as an all time saving of 22 kW by de-lamping, an additional saving of 27 kW through TDC of lighting, direct savings between 13:00 and 22:00 h by closing supply and return air fans of 52 air-handling units with a connected load 400 kW, and an additional saving of 550 kW during the same period by optimizing the cooling production and distribution. In conclusion project achieved an overall reduction in power demand of around 20% between 13:00 to 17:00 h and reduction ranging from 7% to 15% between 17:00 to 20:00 h

Implementation of Energy and Power Saving Scheme in The Avenues Mall

This paper presents the results on an energy audit and subsequent implementation of energy efficient operation and maintenance strategies between April 2008 and March 2009 in Phase 1 of the Avenues mall with total area of 170,000 m2. It has cooling production system with a capacity of 7200 RT and prior to energy audit, its peak power demand was close to 15 MW and annual energy consumption was 84000 MWh/y. Overall reductions of 9919 MWh/y in the annual energy consumption and 345 kW in peak power demand were achieved. The major contributors for the savings were time-of-day control for the air-handling units and lighting and optimization of chilled water flow. The project facilitated a benefit of 19838 KD/y to the Mabanee and company. More importantly, it achieved financial benefits to the Ministry of Electricity and Water of nearly 160,000 KD for reduction in power generation and transmission equipment cost and 372000 KD/y towards reduction in annual electricity subsidy in addition to an environmental benefit of reduction in CO2 emissions by 6940 t/y

An Innovative Approach Towards National Peak Load Management

An innovative approach was developed and implemented in eight governmental buildings to reduce their load during the peak demand hours in summer of 2007. The innovative approach implemented in these buildings included pre-closing treatment (PCT) between 13:00 and 14:00 h and time-of-day control (TDC) after 14:00 h for air conditioning (A/C) and lighting systems. PCT realized an overall reduction of 3.43 MW, a saving of 11.7% of the buildings peak power demand; while TDC realized a total savings of 8.67 MW at 15:00 h, a saving of 30.7% of the buildings peak power demand at that hour. The temperature build up inside the buildings due to PCT and TDC was within the acceptable range, which validated the technical viability of these measures. The implementation of the innovative approach in the eight governmental buildings with a total measured peak demand of 29.3 MW achieved a reduction of 8.89 MW. This power is now available to other users leading to financial savings of $13.5 million for the nation towards the cost of constructing new power plants and distribution network equipment. More importantly, this reduction in peak power demand of well over 30$232 million towards the cost of new power generation equipment and distribution network