Gas phase methanol synthesis with Raman spectroscopy for gas composition monitoring

Applicability of Raman spectroscopy for time-resolved gas composition monitoring during direct methanol synthesis via carbon dioxide hydrogenation was investigated. A series of methanol synthesis experiments with varied reactor conditions was conducted and the reactor outlet stream was analyzed with in-line gas Raman spectroscopy. Concentrations of H₂, CO₂ and CO were determined directly from the acquired spectral data. For evaluation of methanol and water content a data reconciliation algorithm was developed. The algorithm involves estimation of the occurring chemical reactions'' extents by iterative minimization of the difference between concentration values acquired from the experimental data and concentration values computed based on the mass conservation principle. The obtained experimental concentrations were compared and validated against the results of the reactor mathematical modeling, which is based upon a well-established kinetic interpretation of the process. The findings indicate good repeatability and accuracy of the developed gas analysis system, which together with the advantageous temporal resolution of the method, make Raman spectroscopy a promising technique for fast response monitoring of the process.

Applicability of Raman spectroscopy for time-resolved gas composition monitoring during direct methanol synthesis via carbon dioxide hydrogenation is investigated.     

Recent advances in optical diagnosis of oral cancers: Review and future perspectives

Optical diagnosis techniques offer several advantages over traditional approaches, including objectivity, speed, and cost, and these label‐free, noninvasive methods have the potential to change the future workflow of cancer management. The oral cavity is particularly accessible and, thus, such methods may serve as alternate/adjunct tools to traditional methods. Recently, in vivo human clinical studies have been initiated with a view to clinical translation of such technologies. A comprehensive review of optical methods in oral cancer diagnosis is presented. After an introduction to the epidemiology and etiological factors associated with oral cancers currently used, diagnostic methods and their limitations are presented. A thorough review of fluorescence, infrared absorption, and Raman spectroscopic methods in oral cancer diagnosis is presented. The applicability of minimally invasive methods based on serum/saliva is also discussed. The review concludes with a discussion on future demands and scope of developments from a clinical point of view. © 2015 Wiley Periodicals, Inc. Head Neck 38 : E2403–E2411, 2016     

Challenges of Using In Vitro Data for Modeling P-Glycoprotein Efflux in the Blood-Brain Barrier

The efficacy of central nervous system (CNS) drugs may be limited by their poor ability to cross the blood-brain barrier (BBB). Transporters, such as p-glycoprotein, may affect the distribution of many drugs into the CNS in conjunction with the restricted paracellular pathway of the BBB. It is therefore important to gain information on unbound drug concentrations in the brain in drug development to ensure sufficient drug exposure from plasma at the target site in the CNS. In vitro methods are routinely used in drug development to study passive permeability and p-glycoprotein efflux of new drugs. This review discusses the challenges in the use of in vitro data as input parameters in physiologically based pharmacokinetic (PBPK) models of CNS drug disposition of p-glycoprotein substrates. Experience with quinidine demonstrates the variability in in vitro parameters of passive permeability and active p-glycoprotein efflux. Further work is needed to generate parameter values that are independent of the model and assay. This is a prerequisite for reliable predictions of drug concentrations in the brain in vivo.     

Health Related Quality of Life in Diabetic Patients Measured by the Nottingham Health Profile

The aim of the present study was to assess the health related quality of life of adult diabetic patients using the Nottingham Health Profile (NHP) as a measure. A further aim was to describe different Quality of Life (QOL) outcomes in different treatment groups of diabetes. The target population consisted of all registered adult (18 years or older) diabetic patients (n = 2519) in the district of Oulu, a city of 100000 inhabitants in Northern Finland. All these persons were invited to participate in a screening examination for diabetic retinopathy, and the NHP questionnaire was mailed along with this invitation. A total of 1804 patients (72 %) returned the NHP questionnaire when they came to the fundus photography session. The data were analysed by using mean values of NHP dimensions with the 95 % confidence intervals (CI) and the logistic regression analysis to predict the risk (OR) for having at least one health problem in a particular dimension. The results indicated that patients with tablet treatment had significantly lower QOL levels than the ‘general population’ in all NHP dimensions. The diet treatment group patients had lower QOL levels than the ‘general population’ only in the ‘Sleep’ and ‘Social isolation’ dimensions. The diet group had a significantly better QOL level in all six dimensions of QOL of NHP than the tablet treatment or combined treatment (patients treated with tablets and insulin) groups. The tablet treatment and combined treatment groups did not differ significantly in any of the NHP dimensions. The logistic models testing the presence of at least one problem in the NHP dimensions showed that the number of other diseases increased the risk of having QOL problems in all dimensions and duration of the diabetes and the age of the patient had risk increasing effects in four NHP dimensions while the gender had only a small effect on the QOL in diabetic patients. The study shows that the NHP questionnaire as a general measure of the QOL reveals differences in the QOL between the different treatment groups and between diabetic patients and general population.     

Passive oral drug absorption can be predicted more reliably by experimental than computational models—Fact or myth

This study assessed the prediction power of experimental and computational models that are widely used to predict human passive intestinal absorption. The models evaluated included two cell lines, three artificial membrane models, in vivo rat experiments, and seven previously described computational quantitative structure property relationship models based on human absorption values. The data sets used in the assessment of the models were carefully chosen from the literature, and different models were compared using the same compounds to ensure objective results. Three of the computational models were found to be significantly more reliable in predicting human passive intestinal absorption than the artificial membrane models that have been developed for the prediction of passive intestinal absorption. Two of these computational models were found to be as reliable as the Caco-2 and the 2/4/A1 cell lines and, furthermore, one of the models was able to predict the absorption of a set of 65 drugs nearly as well as absorption studies in rats. The unexpectedly good prediction power of the simple computational models with high throughput makes them ideal tools in the early screening of drug candidates, whereas laborious cell culture models and animal studies can be useful in the later phases when detailed information about the transport mechanisms is needed.     

Pharmacokinetic role of L-type amino acid transporters LAT1 and LAT2

LAT1 and LAT2 are heterodimeric large amino acid transporters that are expressed in various tissues, including the intestinal wall, blood-brain barrier, and kidney. These transporters consist of membrane spanning light chain and heavy chain, and they act as 1:1 exchangers in concert with other amino acid transporters. Only a few drugs (less than 10) are substrates of LAT1 and LAT2, including l-DOPA, alpha-methyldopa, melphalan, and gabapentin. The mechanisms and substrates have been mostly elucidated using mammalian cells and Xenopus oocytes. The in vivo relevance of LAT1 and LAT2 in pharmacokinetics is obscure, because contradictory findings have been reported. It is difficult to make quantitative pharmacokinetic conclusions about LAT1 and LAT2. This is due to the possible involvement of other transporters (including cross-linked heterodimers of light chain with different heavy chains, other overlapping transporters, for example TAT1), competing endogenous amino acids, and saturation phenomena. This review presents the current functional knowledge on LAT1 and LAT2 with emphasis on their potential involvement in pharmacokinetics.     

The effect of spraying and rolling process factors on styrene emission during the application of unsaturated polyester resins

In recent years the awareness of the problems caused by styrene emission during the processing of unsaturated polyester resins has enlarged. The spray-up application of gel coats is especially problematic, and it produces high styrene emission rates. The emission of styrene has been reduced through material changes, work practice controls, and add-on controls. However, the influence of the spray-up process factors on styrene emission has not been studied before. The aim of this study was to examine possibilities to reduce styrene emission by optimization of spray-up process factors. The following factors were studied under controlled laboratory conditions: orifice size and angle of the spray gun tip, spraying pressure, distance between spray gun and mold, and shape of the mold. The influence of the rolling pattern during lamination was also studied. Several significant factors were found. High pressure and long spraying distance increased both the unit styrene emission and the emission rate. The orifice size had two effects; a large orifice decreased the amount of styrene emitted per sprayed amount of resin but increased the emission rate of styrene. The shape of the mold did not affect the styrene emission. Styrene emission is greater if the entire mold area is rolled. To achieve lower emission is it necessary to roll an area as small as possible; this is especially important if a large mold is laminated. The results showed that emission of styrene can be reduced significantly by an optimal selection of the spray gun settings and the way of working. Optimal settings also increased the transfer efficiency resulting in decreased material loss.     

Systematic review of evidence for the benefits of telemedicine

A systematic review of telemedicine assessments based on searches of electronic databases between 1966 and December 2000 identified 66 scientifically credible studies that included comparison with a non-telemedicine alternative and that reported administrative changes, patient outcomes, or results of economic assessment. Thirty-seven of the studies (56%) suggested that telemedicine had advantages over the alternative approach, 24 (36%) also drew attention to some negative aspects or were unclear whether telemedicine had advantages and five (8%) found that the alternative approach had advantages over telemedicine. The most convincing evidence on the efficacy and effectiveness of telemedicine was given by some of the studies on teleradiology (especially neurosurgical applications), telemental health, transmission of echocardiographic images, teledermatology, home telecare and on some medical consultations. However, even in these applications, most of the available literature referred only to pilot projects and to short-term outcomes. Few papers considered the long-term or routine use of telemedicine. For several applications, including teleradiology, savings and sometimes clinical benefit were obtained through avoidance of travel and associated delays. Studies of home care and monitoring applications showed convincing evidence of benefit, while those on teledermatology indicated that there were cost disadvantages to health-care providers, although not to patients. Forty-four of the studies (67%) appeared to have potential to influence future decisions on the telemedicine application under consideration. However, a number of these had methodological limitations. Although useful clinical and economic outcomes data have been obtained for some telemedicine applications, good-quality studies are still scarce and the generalizability of most assessment findings is rather limited.