Determining the cost of predictive component replacement in order to assist with maintenance decision-making

Asset and maintenance managers are often confronted with difficult decisions related to asset replacement or repair. Various analytical models, such as decision analysis and simulation, can assist a manager in making better decisions. This paper proposes that by combining renewal theory with decision analysis methods, the expected value (EV) of information for non-repairable components can be calculated. Subsequently, it is proposed that this method can be used to determine the expected replacement cost per unit time of predictive maintenance. It is argued that this predicted cost will give the maintenance decision-maker the ability to compare it to the cost of alternative maintenance strategies when choosing between strategies. Although this paper is limited to non-repairable components, the theory and methodology can also be applied to repairable systems.Bate- en instandhoudingsbestuurders word dikwels gekonfronteer met moeilike besluite rakende die vervanging of herstel van fisiese bates. Verskeie analitiese modelle, soos besluitsanalise en simulasie, kan die bestuurder help om beter besluite te neem. Hierdie artikel stel voor dat deur hernubare teorieë te kombineer met besluitnemingsmetodes, die verwagte waarde van inligting vir nie-herstelbare komponente bereken kan word. Gevolglik word dit voorgestel dat hierdie metode gebruik kan word om die verwagte koste per tyd eenheid van voorspelbare instandhouding te bereken. Daar word geargumenteer dat hierdie beraamde koste die instandhoudings-besluitnemer die vermoë sal gee om die koste van verskeie instandhoudingstrategieë te vergelyk wanneer daar gekies word tussen strategieë. Hierdie artikel sal beperk word tot nie-herstelbare komponente, maar deur soortgelyke prosesse te volg, kan die teorie uitgebrei word na herstelbare stelsels.http://sajie.journals.ac.za/pubam201

A comparison of the efficacy of various disinfection protocols in endodontic treatment : an in vitro study

INTRODUCTION : Disinfection is the main objective of root canal preparation and whilst irrigation is most commonly used, another method is Photo-activated Disinfection (PAD). AIMS AND OBJECTIVES : The aim of this in vitro study was to compare the efficacy of eradication of bacteria from root canals by six different disinfection protocols. METHODS : Root canals of 84 extracted human teeth were prepared to a standardised size and taper. The teeth were sterilised and then inoculated with E. faecalis. The teeth were randomly assigned to one of seven groups (n = 12), each of which underwent a different disinfection protocol. Dentine samples were plated onto BHI plates and incubated anaerobically. After five days, colony-forming units (cfu) were counted. The Pairwise Wilcoxon Rank Sum test and the Kruskal-Wallis test were used for statistical analysis of the data. RESULTS : The most effective disinfection protocol was: 3% NaOCl with 2% CHX, followed by 3% NaOCl with PAD, Chlor-XTRA and 2% CHX. The 3% NaOCl-protocol performed significantly better than PAD and distilled water. The PAD-protocol performed significantly better than distilled water. CONCLUSION : The most efficient protocol in eradicating E. faecalis from the root canals was 3% NaOCl followed by irrigation with 2% CHX.The Professor Cornelis H Pameijer Fellowshiphttp://www.sada.co.zaam201

The efficacy and safety of nine South African medicinal plants in controlling Bacillus anthracis Sterne vaccine strain

BACKGROUND : Anthrax is a zoonotic disease caused by Bacillus anthracis, a Gram-positive spore-forming bacterium. The presence of the bacteria and the toxins in the blood of infected hosts trigger a cascade of pathological events leading to death. Nine medicinal plants with good activities against other bacteria were selected to determine their in vitro antibacterial activity against Bacillus anthracis Sterne strain. The cytotoxicity of the extracts on Vero kidney cells was also determined. RESULTS : The minimum inhibitory concentration (MIC) values of the extracts against Bacillus anthracis Sterne strain ranged from 0.02 to 0.31 mg/ml. Excellent MIC values were observed for the following plant species: Maesa lanceolata (0.02 mg/ml), Bolusanthus speciosus, Hypericum roeperianum, Morus mesozygia (0.04 mg/ml) and Pittosporum viridiflorum (0.08 mg/ml). The total antibacterial activity of the extracts ranged from 92 to 5562 ml/g. Total activity presents the volume to which the extract from 1 g of plant material can be diluted and still inhibit microbial growth. Maesa lanceolata and Hypericum roeperianum had the highest total activity with values of 5562 and 2999 ml/g respectively. The extracts of Calpurnia aurea had the lowest total activity (92 ml/g). The cytotoxicity determined on Vero cells indicated that most of the extracts were relatively non-toxic compared to doxorubicin (LC50 8.3 ± 1.76 μg/ml), except for the extracts of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea with LC50 values at 2.38 ± 0.25, 5.20 ± 0.24 and 13 ± 2.26 μg/ml respectively. The selectivity index (SI) ranged from 0.02 to 1.66. Hypericum roeperianum had the best selectivity index, (SI = 1.66) and Elaeodendron croceum had lowest value (SI = 0.02). CONCLUSIONS : The crude acetone extracts of the selected plant species had promising antibacterial activity against Bacillus anthracis. Maesa lanceolata extracts could be useful as a disinfectant and Hypericum roeperianum could be useful to protect animals based on its high total activity and selectivity index. Further investigation of these plant extracts may lead to the development of new therapeutic agents to protect humans or animals against anthrax.The National Research Foundation of South Africa (Eloff 95991) and the University of Pretoria.http://www.biomedcentral.com/bmccom/plementalternmedam2016Paraclinical Science

Antimicrobial efficacy of nine different root canal irrigation solutions

Endodontic therapy is a debridement procedure that requires removal of the irritants from the canal and periapical tissues if the treatment is to be successful. It is well established that bacteria are the main etiological factors in the development of dentinal caries and its progression to pulpal and periapical disease. E. faecalis is the bacterial species most frequently recovered from root-filled teeth. Studies have shown that E. faecalis is able to withstand a high alkaline environment such as the one generated by calcium hydroxide. The resistance appears to be related to a cell proton-pump that is necessary for survival of the bacterium at high pH. Therefore, E. faecalis is able to form biofilms even in calcium-hydroxide-medicated root canals. In addition, under starved conditions, this resilient organism shows tolerance to sodium hypochlorite, heat, hydrogen peroxide, acid and ethanol. E. faecalis can also survive extended periods of starvation in water, within water-filled dentinal tubules, and in human serum.http://www.sada.co.zaam201

The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts

Background: The development of antibiotic resistant bacteria stems from a number of factors, including inappropriate use of antibiotics in human and animal health and their prolonged use as growth promoters at sub-clinical doses in poultry and livestock production. We were interested in investigating plants that could be useful in protecting humans or animals against diarrhoea. We decided to work on extracts of nine plant species with good activity against Escherichia coli based on earlier work in the Phytomedicine Programme. Leaves of nine medicinal plant species with high antibacterial activity against Escherichia coli were extracted with acetone and their minimal inhibitory concentration (MIC) values determined using a microplate serial dilution technique against Gram-positive (Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa) bacteria. Bioautography was used to determine the number of bioactive compounds in each extract. In vitro safety of the extracts was determined using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay on Vero cells. Results: The extracts were active against all the pathogens with average MICs ranging from 0.02 to 0.52 mg/ml. As expected E. coli was relatively sensitive, while E. faecalis and S. Typhimurium were more resistant to the extracts (average MICs of 0.28 mg/ml and 0.22 mg/ml respectively). Cremaspora triflora and Maesa lanceolata leaf extracts had higher activity than the other extracts against Gram-positive and Gram-negative pathogens with mean MICs of 0.07 mg/ml and 0.09 mg/ml respectively. Extracts of Maesa lanceolata and Hypericum roeperianum had the highest total antibacterial activity (TAA) at 1417 and 963 ml/g respectively. All extracts with the exception of that of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea had relatively low cytotoxicity with LC50 >20 μg/ml. Cremaspora triflora had the best selectivity index (SI) against S. aureus and E. coli of 2.87 and 1.15 respectively. Hypericum roeperianum had a SI of 1.10 against B. cereus. Bioautography revealed 1–6 visible antimicrobial compounds that were generally non-polar. Conclusions: There was a weak positive, but statistically non-significant correlation between the potency of the extracts and their cytotoxicity (R= 0.45, ρ > 0.05). The activity of the extracts on the test bacteria was in some cases not correlated with cytotoxicity, as shown by selectivity indices >1. This means that cellular toxicity was probably not due to compounds with antibacterial activity. Some of the extracts had a good potential for therapeutic use against the bacterial pathogens or for application in treating diarhoea. It does not appear that activity against E. coli is a good predictor of activity against Gram-negative rather than Gram-positive bacteria. Further investigation is in progress on C. triflora and H. roeperianum, both of which had promising activities and potential safety based on cytotoxicity.The National Research Foundation of South Africa (Eloff IPPR 953991), the Medical Research Council of South Africa and the University of Pretoria.https://bmccomplementalternmed.biomedcentral.com/am2017Paraclinical Science

The anti-arthritic, anti-inflammatory, antioxidant activity and relationships with total phenolics and total flavonoids of nine South African plants used traditionally to treat arthritis

BACKGROUND : Oxidative stress predisposes the human and animal body to diseases like cancer, diabetes, arthritis, rheumatoid arthritis, atherosclerosis and chronic inflammatory disorders. Hence, this study seeks to determine the antioxidant, anti-inflammatory and anti-arthritic activities of acetone leaf extracts of nine South African medicinal plants that have been used traditionally to treat arthritis and inflammation. METHODS : The anti-inflammatory activity of the extracts was determined by investigating inhibition of nitric oxide production in lipopolysaccharide activated RAW 264.7 macrophages as well as 15-lipoxygenase enzyme inhibition. An anti-protein denaturation assay was used to determine the anti-arthritic properties of the extracts. The antioxidant activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethyl-benzthiazoline-6-sulfonic acid) (ABTS) radical scavenging assays and ferric reducing antioxidant power (FRAP). The total phenolic and total flavonoid concentration of extracts were determined by using standard methods. RESULTS : All extracts inhibited nitric oxide production in a dose-dependent manner in the LPS-stimulated RAW 264.7 macrophages. Extracts of Maesa lanceolata and Heteromorpha arborescens inhibited NO production by 99.16 % and 89.48 % at a concentration of 30 μg/ml respectively. Elaeodendron croceum and Calpurnia aurea extracts had strong activity against 15-lipoxygenase activity with IC50 values of 26.23 and 34.70 μg/ml respectively. Morus mesozygia and Heteromorpha arborescens extracts had good in vitro anti-arthritic activity with IC50 values of 11.89 and 53.78 μg/ml, the positive control diclofenac sodium had IC50 value of 32.37 μg/ml. The free radical scavenging activity of the extracts in DPPH assays ranged between 7.72 and 154.77 μg/ml. Trolox equivalent antioxidant capacity (TEAC) and FRAP values ranged from 0.06 to 1.32 and 0.06 to 0.99 respectively. CONCLUSIONS : Results from this study support the traditional use of the selected medicinal plants in the management of arthritis and other inflammatory conditions. The free radical scavenging capacity of the extracts may be related to an immune boosting potential.ILE is a PhD student in the Phytomedicine Programme. JPD (PhD) is a post-doctoral fellow in the Phytomedicine Programme. FSB (PhD) is Senior Lecturer and mentor in the Phytomedicine Programme. LJM (PhD) is an Associate Professor and the current leader of the Phytomedicine Programme. JNE (DSc) is a Professor and the founder of the Phytomedicine Programme in the Department of Paraclinical Sciences of the Faculty of Veterinary Science, University of Pretoria.The National Research Foundation of South Africa (Eloff IPPR 953991) and the University of Pretoria.http://www.biomedcentral.com/bmccom/plementalternmedam2016Paraclinical Science

In vitro evaluation of root canals obturated with four different techniques. Part 2 : Apical leakage

No abstract available.www.sada.co.zaam201

In vitro evaluation of root canals obturated with four different techniques. Part 1 : Radiographic evaluation

No abstract available.http://www.sada.co.zaam201

In vitro evaluation of root canals obturated with four different techniques. Part 3 : Obturation of lateral canals

According to Schilder,1,2,3 the main objective of endodontic treatment procedures should be the cleaning and filling of the root canal in its entire extent, including all lateral canals and apical ramifications.http://www.sada.co.zaam2013mn201

Potency and selectivity indices of acetone leaf extracts of nine selected South African trees against six opportunistic Enterobacteriaceae isolates from commercial chicken eggs

BACKGROUND : The rise in antimicrobial resistance in a plethora of nosocomial and opportunistic bacterial pathogens often isolated from commercial eggs, poses a serious public health concern. The existence of these contaminants may also serve as a drawback in the current efforts of improving the well-being of immunocompromised patients. The aim of this study was to determine the efficacy of plant extracts that had good activity on Escherichia coli in previous word on pathogens isolated from eggs for possible use in combating pathogens from eggs. METHODS : Acetone leaf extracts of nine trees with good activities against Escherichia coli were tested for their in vitro antibacterial activity against six opportunistic bacterial isolates from commercial eggs (Stenotrophomonas maltophilia, Klebsiella pneumoniae, Salmonella serotype Typhimurium, Proteus mirabilis, Enterobacter cloacae and Escherichia coli) using a serial microdilution method with tetrazolium violet as indicator of growth. Cytotoxicity was determined using a tetrazolium-based colorimetric assay against Vero kidney cells, and selectivity index calculated. RESULTS : The MIC values range of the different extracts against Stenotrophomonas maltophilia was 0.08-0.31 mg/ml, Klebsiella pneumonia 0.08-0.63 mg/ml, Salmonella ser. Typhimurium 0.08-0.63 mg/ml, Proteus mirabilis 0.02-1.25 mg/ ml, Enterobacter cloacae 0.08-0.31 mg/ml and Escherichia coli 0.08-0.16 mg/ml respectively. Escherichia coli was the most sensitive while Proteus mirabilis was most resistant pathogen to the different test extracts, with mean MIC values of 0.08 mg/ml and 0.46 mg/ml respectively. Cremaspora triflora extracts had good activity against all the pathogenic egg isolates, with the exception of Proteus mirabilis. Maesa lanceolata and Elaeodendron croceum had the best total antibacterial activity (TAA), while generally the selectivity index of the extract was low (SI < 1). CONCLUSION : The exceptional activity of C. triflora extracts suggests that the plant has potential as a therapeutic agent against some members of the Enterobacteriaceae. Further pharmacological investigations may be interesting in the search for new antimicrobial leads.This manuscript is an output of a Ph. D. research project.The National Research Foundation of South Africa (Eloff IPPR 953991), the South African Medical Research Council and the University of Pretoria.http://www.biomedcentral.com/bmccom/plementalternmedam2017Food ScienceParaclinical Science