Two-Photon Excited Fluorescence Detection Technology in Screening for Methicillin-Resistant Staphylococcus aureus

Control of the world-wide spread of methicillin-resistant Staphylococcus aureus (MRSA) has been unsuccessful in most developed countries. A few countries have been able to maintain a low MRSA prevalence, plausibly due to their strict MRSA control policies. Such policies require wide-scale screening of patients with suspected MRSA colonization, in order to nurse the MRSA-positive patients in contact isolation. The aim of this study was to develop and introduce a 2-photon excited fluorescence detection (TPX) technique for screening of MRSA directly from clinical samples. The assay principle involves specific online immunometric monitoring of S. aureus growth under selective antibiotic pressure. After the novel TPX approach had been set up, its applicability for the detection of MRSA was evaluated using a large MRSA collection including practically all epidemic MRSA strains identified in Finland between 1991 and 2009. The TPX assay was found both sensitive (97.9%) and specific (94.1%) in this epidemiological setting, illustrating that the method is tolerant to wide biological variation as well as to environments with rapidly emerging MRSA strains. When MRSA was screened directly from colonization samples, all patients positive for MRSA by conventional methods were positive also by the TPX assay. The assay capacity was 48 samples per a test run, and the median time required for confirmation of a true-positive screening test result was 3 h 26 min. Collectively, the findings presented in this thesis suggest that the TPX MRSA screening assay could be applicable for direct screening of MRSA colonization samples without any prior steps of isolation. This can potentially mean that contact isolation of suspected carriers testing negative could be discontinued earlier, thereby reducing the costs and burden associated with the containment of MRSA. In case of infection, a positive test result would ensure an early onset of effective therapy.

Accuracy Analysis of Frequency Converter Estimates in Diagnostic Applications

Transportation of fluids is one of the most common and energy intensive processes in the industrial and HVAC sectors. Pumping systems are frequently subject to engineering malpractice when dimensioned, which can lead to poor operational efficiency. Moreover, pump monitoring requires dedicated measuring equipment, which imply costly investments. Inefficient pump operation and improper maintenance can increase energy costs substantially and even lead to pump failure. A centrifugal pump is commonly driven by an induction motor. Driving the induction motor with a frequency converter can diminish energy consumption in pump drives and provide better control of a process. In addition, induction machine signals can also be estimated by modern frequency converters, dispensing with the use of sensors. If the estimates are accurate enough, a pump can be modelled and integrated into the frequency converter control scheme. This can open the possibility of joint motor and pump monitoring and diagnostics, thereby allowing the detection of reliability-reducing operating states that can lead to additional maintenance costs. The goal of this work is to study the accuracy of rotational speed, torque and shaft power estimates calculated by a frequency converter. Laboratory tests were performed in order to observe estimate behaviour in both steady-state and transient operation. An induction machine driven by a vector-controlled frequency converter, coupled with another induction machine acting as load was used in the tests. The estimated quantities were obtained through the frequency converter’s Trend Recorder software. A high-precision, HBM T12 torque-speed transducer was used to measure the actual values of the aforementioned variables. The effect of the flux optimization energy saving feature on the estimate quality was also studied. A processing function was developed in MATLAB for comparison of the obtained data. The obtained results confirm the suitability of this particular converter to provide accurate enough estimates for pumping applications.

Biomolecular screening for inhibitors of butyrylcholinesterase : identification and characterization using in vitro and in silico tools

Drug discovery is a continuous process where researchers are constantly trying to find new and better drugs for the treatment of various conditions. Alzheimer’s disease, a neurodegenerative disease mostly affecting the elderly, has a complex etiology with several possible drug targets. Some of these targets have been known for years while other new targets and theories have emerged more recently. Cholinesterase inhibitors are the major class of drugs currently used for the symptomatic treatment of Alzheimer’s disease. In the Alzheimer’s disease brain there is a deficit of acetylcholine and an impairment in signal transmission. Acetylcholinesterase has therefore been the main target as this is the main enzyme hydrolysing acetylcholine and ending neurotransmission. It is believed that by inhibiting acetylcholinesterase the cholinergic signalling can be enhanced and the cognitive symptoms that arise in Alzheimer’s disease can be improved. Butyrylcholinesterase, the second enzyme of the cholinesterase family, has more recently attracted interest among researchers. Its function is still not fully known, but it is believed to play a role in several diseases, one of them being Alzheimer’s disease. In this contribution the aim has primarily been to identify butyrylcholinesterase inhibitors to be used as drug molecules or molecular probes in the future. Both synthetic and natural compounds in diverse and targeted screening libraries have been used for this purpose. The active compounds have been further characterized regarding their potencies, cytotoxicity, and furthermore, in two of the publications, the inhibitors ability to also inhibit Aβ aggregation in an attempt to discover bifunctional compounds. Further, in silico methods were used to evaluate the binding position of the active compounds with the enzyme targets. Mostly to differentiate between the selectivity towards acetylcholinesterase and butyrylcholinesterase, but also to assess the structural features required for enzyme inhibition. We also evaluated the compounds, active and non-active, in chemical space using the web-based tool ChemGPS-NP to try and determine the relevant chemical space occupied by cholinesterase inhibitors. In this study, we have succeeded in finding potent butyrylcholinesterase inhibitors with a diverse set of structures, nine chemical classes in total. In addition, some of the compounds are bifunctional as they also inhibit Aβ aggregation. The data gathered from all publications regarding the chemical space occupied by butyrylcholinesterase inhibitors we believe will give an insight into the chemically active space occupied by this type of inhibitors and will hopefully facilitate future screening and result in an even deeper knowledge of butyrylcholinesterase inhibitors.

Homogeneous assay technologies in drug screening: Quenching Resonance Energy Transfer (QRET) technique

Information gained from the human genome project and improvements in compound synthesizing have increased the number of both therapeutic targets and potential lead compounds. This has evolved a need for better screening techniques to have a capacity to screen number of compound libraries against increasing amount of targets. Radioactivity based assays have been traditionally used in drug screening but the fluorescence based assays have become more popular in high throughput screening (HTS) as they avoid safety and waste problems confronted with radioactivity. In comparison to conventional fluorescence more sensitive detection is obtained with time-resolved luminescence which has increased the popularity of time-resolved fluorescence resonance energy transfer (TR-FRET) based assays. To simplify the current TR-FRET based assay concept the luminometric homogeneous single-label utilizing assay technique, Quenching Resonance Energy Transfer (QRET), was developed. The technique utilizes soluble quencher to quench non-specifically the signal of unbound fraction of lanthanide labeled ligand. One labeling procedure and fewer manipulation steps in the assay concept are saving resources. The QRET technique is suitable for both biochemical and cell-based assays as indicated in four studies:1) ligand screening study of β2 -adrenergic receptor (cell-based), 2) activation study of Gs-/Gi-protein coupled receptors by measuring intracellular concentration of cyclic adenosine monophosphate (cell-based), 3) activation study of G-protein coupled receptors by observing the binding of guanosine-5’-triphosphate (cell membranes), and 4) activation study of small GTP binding protein Ras (biochemical). Signal-to-background ratios were between 2.4 to 10 and coefficient of variation varied from 0.5 to 17% indicating their suitability to HTS use.

Combination of pulsed corona discharge with TiO2 photocatalysis: verification of hypothesis

The oxidation potential of pulsed corona discharge concerning aqueous impurities is limited in respect to certain refractory compounds. This may be enhanced in combination of the discharge with catalysis/photocatalysis as developed in homogeneous gas-phase reactions. The objective of the work consists of testing the hypothesis of oxidation potential enhancement in combination of the discharge with TiO2 photocatalysis applied to aqueous solutions of refractory oxalate. Meglumine acridone acetate was included for meeting the practical needs. The experimental research was undertaken into oxidation of aqueous solutions under conditions of various target pollutant concentrations, pH and the pulse repetition rate with plain electrodes and the electrodes with TiO2 attached to their surface. The results showed no positive influence of the photocatalyst, the pollutants were oxidized with the rate identical within the accuracy of measurements. The possible explanation for the observed inefficiency may include low UV irradiance, screening effect of water and generally low oxidation rate in photocatalytic reactions. Further studies might include combination of electric discharge with ozone decomposition/radical formation catalysts.

The Effects of the Breast Cancer Mammography Screening Programme in Women aged 40 to 84 years in Turku, Finland (1987-2009)

The objective of this thesis was to evaluate whether a more extensive mammography screening programme (TurkuMSP) conducted by the city of Turku, had an effect on breast cancer (BC) incidence, survival, or mortality in years 1987 to 2009. Despite the fact that some studies have suggested a 20 percent reduction in BC mortality due to mammography screening, there are findings of harm to subjects, which are claimed to negate the benefits of screening. Thus, the aims of this study are most pertinent. A total of 176 908 screening examinations were performed in 36 000 women aged 40−74 during the years 1987−1997. In all, 685 primary BCs were found in the screened women, either screen-detected (n=531) or during screening intervals (n=154). Survival and BC recurrence rate of women with screen-detected BC was compared to 184 women with clinical BCs detected among individuals who did not take part in the screening. The invitation interval, which may influence the outcome, was studied in the age group 40 to 49 by inviting those born in even calendar years annually for mammography screening and those born in odd years, triennially. In addition, BC incidence and mortality in the total female population of Turku aged 40 to 84 years was compared with the respective figures of Helsinki and the rest of Finland, both during the pre-screening era (1976-1986) and the screening era (1987-2009). The study was designed to compare women by age groups, because women aged 50 to 59 were generally screened in all of Finland, whereas only in Turku women aged 40 to 49 and 60 to 74 were screened in addition. Data regarding cancer recurrence were derived from the Finnish Cancer Registry and data on deaths were collected from Statistics Finland. In survival analyses, screened women with invasive BC had a significantly higher survival rate than the women with clinical BC. The survival benefit started to appear already during the first follow-up years and was evident in all age groups. A marginal survival extension was also seen in screened women when BC had spread to ipsilateral axillary nodes already at diagnosis. Recurrence-free survival rate after BC treatment was significantly more favorable among the screened women compared with women with BC found clinically. The screening invitation interval did not significantly influence BC mortality in the subset of women aged 40 to 49 years. There were no consistent differences in the changes of BC incidence between Turku and the comparison areas during the screening era. In Turku, the BC mortality incidence in women aged 55−69 years was significantly lower during the screening era (from 1987 to 1997) compared with the pre-screening era, whereas no such change was found in the city of Helsinki or Tampere. When comparing the changes in incidence-based BC mortality during years 1987 to 2009 in Turku to those of Helsinki and the rest of Finland, there was a suggestion of more than 20 percent lower mortality in Turku among oldest age group (75-84 years) compared with the reference residential areas, but the differences were not consistently significant. Interpretation of the study results should be made with caution because there were no random control groups, and on the other hand, the number of cases in subgroups was fairly low to yield definite conclusions. Also due to the many statistical analyses, some of the findings may be due to chance. The results are, however, suggestive for a decrease of BC mortality in the elderly age groups due to wide mammography screening. This finding needs confirmation in further studies before recommending an expansion of mammography screening to women up to the age of 74 years

Accuracy improvement of a demand forecasting model

This research concerns different statistical methods that assist to increase the demand forecasting accuracy of company X’s forecasting model. Current forecasting process was analyzed in details. As a result, graphical scheme of logical algorithm was developed. Based on the analysis of the algorithm and forecasting errors, all the potential directions for model future improvements in context of its accuracy were gathered into the complete list. Three improvement directions were chosen for further practical research, on their basis, three test models were created and verified. Novelty of this work lies in the methodological approach of the original analysis of the model, which identified its critical points, as well as the uniqueness of the developed test models. Results of the study formed the basis of the grant of the Government of St. Petersburg.

Accuracy in book papers' sales forecasting

The main objective of this thesis was to study if the quantitative sales forecasting methods will enhance the accuracy of the sales forecast in comparison to qualitative sales forecasting method. A literature review in the field of forecasting was conducted, including general sales forecasting process, forecasting methods and techniques and forecasting accuracy measurement. In the empirical part of the study the accuracy of the forecasts provided by both qualitative and quantitative methods is being studied and compared in the case of short, medium and long term forecasts. The SAS® Forecast Server –tool was used in creating the quantitative forecasts.

Screening of power to gas projects

The purpose of this thesis was the screening of power to gas projects worldwide and reviewing the technologies used and applications for the end products. This study focuses solely on technical solutions and feasibility, economical profitability is excluded. With power grids having larger penetrations of intermittent sources such as solar and wind power, the demand and production cannot be balanced in conventional methods. Technologies for storing electric power in times of surplus production are needed, and the concept called power to gas is a solution for this problem. A total of 57 projects mostly located in Europe were reviewed by going through publications, presentations and project web pages. Hydrogen is the more popular end product over methane. Power to gas is a viable concept when power production from intermittent sources needs to be smoothed and time shifted, when carbon free fuels are produced for vehicles and when chemical industry needs carbon neutral raw materials.