The laser in biophysical and analytical chemistry: Investigating biophysical processes and dynamics, as well as analytical techniques, as applied to systems of biological and chemical relevance

The unique properties of the laser have permitted the investigation of important biological molecules and systems, and aided in the development of the F-Detector, important in the area of food safety. The laser offers narrow pulses of high peak power to probe chromophore interactions with micelles, protein structure and dynamics, excited-state photophysics, and selective fluorescence detection;Using the laser based time-correlated single photon counting technique, the effect of a surfactant on the fluorescence properties of indole, 1-methylindole, and 3-methylindole in aqueous solutions was investigated. 3-methylindole partitions very well into the Brij-35 micelle as indicated by the triple exponential fluorescence decays. An equilibrium constant of 2.6 x 104 M-1 was determined for the 3-methylindole/micelle interaction;Using the same time-resovled technique, tropomyosin mutants containing either tryptophan, 5-hydroxytryptophan, or 7-azatryptophan were expressed in Escherichia coli and their fluorescence properties studied;Utilizing fluorescence upconversion, measurements of hypericin and its methylated analog, O-hexamethoxyhypericin, which possesses no labile protons, confirm excited-state hydrogen atom transfer as the primary photophysical event in hypericin;Laser based pump-probe transient absorption spectroscopy was utilized to determine that the activation energies for excited-state hydrogen atom transfer of hypericin and hypocrellin are respectively, 0.044 +/- 0.008 and 2.12 +/- 0.070 kcal/mol. The low activation energies are consistent with the hydrogen atom transfer reactions being adiabatic;The laser based F-Detector was designed and built for selective detection of fecal and ingesta contamination on meat carcasses as they are processed. F420 was initially utilized as the fluorescent marker, but later investigations revealed the utility of pheophorbide as a marker for fecal contamination. A 100 ms detector time constant offers instantaneous detection. Pheophorbide detection limits are as low as 10-10 M;These investigations illustrate the utility and importance of the laser in biophysical and analytical chemistry. The experimental information obtained would otherwise be almost impossible to obtain using more conventional light sources

Temperature Dependence of the Excited-State Intramolecular Proton Transfer Reaction in Hypericin and Hypocrellin A

The excited-state intramolecular proton-transfer reactions of hypericin and hypocrellin A are measured as a function of temperature in an ethanol/methanol mixture. The data yield activation energies of 0.044 ± 0.008 and 2.12 ± 0.070 kcal/mol for hypericin and hypocrellin A, respectively. The negligible activation energy of hypericin is consistent with previous suggestions that the proton-transfer reaction is adiabatic (K. Das et al., J. Phys. Chem. 1997,101A, 3241.) and that a very low-amplitude displacement in at least one other coordinate be taken into account in order to describe the reaction dynamics. The proton transfer for hypocrellin is also considered to occur in the adiabatic regime, but the significant activation energy suggests that a larger amplitude motion than that for the case of hypericin comprises part of the reaction coordinate. Much of the barrier cited above for hypocrellin A results from the temperature dependence of the viscosity of the solvent mixture. The viscosity independent part of the activation barrier is 0.41 ± 0.088 kcal/mol

Fluorescence of Dietary Porphyrins as a Basis for Real-Time Detection of Fecal Contamination on Meat

Digestion of green plants in the gastrointestinal (GI) tract produces degradation products from chlorophyll that cause ingesta and feces to be highly fluorescent. This property was exploited for development and construction of instruments to noninvasively detect minute quantities of feces on meat samples in real time. The presence of feces on meat products is a primary source of foodborne pathogens, such as Escherichia coli O157:H7 and Salmonella. This new technology provides a rapid and accurate alternative to the practice of visual inspection and augments more time-consuming biological testing methods. This innovation can assist meat processors and government inspectors in their efforts to provide safe and wholesome food to consumers

Domain Structure of the Staphylococcus aureus Collagen Adhesin

Sequence analysis of surface proteins from Gram-positive bacteria indicates a composite organization consisting of unique and repeated segments. Thus, these proteins may contain discrete domains that could fold independently. In this paper, we have used a panel of biophysical methods, including gel permeation chromatography, analytical ultracentrifugation, circular dichroism, and fluorescence spectroscopy, to analyze the structural organization of the Staphylococcus aureus collagen adhesin, CNA. Our results indicate that the structure, function, and folding of the ligand-binding domain (A) are not affected by the presence or absence of the other major domain (B). In addition, little or no interaction is observed between the nearly identical repeat units within the B domain. We propose that CNA is indeed a mosaic protein in which the different domains previously indicated by sequence analysis operate independently

Clinical Educator and Student Perceptions of iPad™ Technology to Enhance Clinical Supervision: The Electronically-Facilitated Feedback Initiative (EFFI)

Purpose: Growing demands placed upon healthcare systems require more health professionals to be trained. Clinical placement education is an integral component of health professional training, however accommodating increasing numbers of student placements is a challenge for health services. Personal digital assistants such as iPads™ may assist in delivery of clinical education, by facilitating transfer of knowledge and skills from clinical educators to health professional students, however such an initiative has not been formally investigated. The present study sought to explore perceptions of clinical educators and allied health students regarding the impact of an iPad™-based feedback delivery system on student reflection and learning. Methods: A pilot study was performed using iPads™ with specialised software to deliver electronic formative feedback to physiotherapy, occupational therapy and speech pathology students during clinical placements. Students and clinical educators completed a questionnaire exploring advantages and disadvantages of the technology. Results: Nine clinical educators and 14 students participated and completed the survey. Clinical educators largely (n=7, 78%) reported the electronic feedback system was easy to use and 67% (n=6) reported it improved the quality of feedback provided to students. Five (56%) clinical educators thought electronic feedback improved student performance. Most students (n=10, 71%) reported electronic feedback facilitated reflection upon performance, and 64% (n=9) reported improved performance as a result. Disadvantages included poor wireless internet access and software inefficiencies (n=7 [78%] clinical educators, n=7 [50%] students), and difficulties using iPads™ in settings requiring infection control (n=2 [22%] clinical educators). Conclusions: Clinical educators and students perceived electronic feedback as a positive adjunct to student learning on clinical placement, however technological and software interface factors need to be considered for implementation in some settings

Oral and dermal toxicity of alkenones extracted from Isochrysis species

Author Posting. © Bioscience Research Institute, 2020. This article is posted here by permission of Bioscience Research Institute for personal use, not for redistribution. The definitive version was published in McIntosh, K., Sarver, J., Mell, K., Terrero, D. J., Ashby, C. R., Reddy, C., O’Neil, G., Ramapuram, J. B., & Tiwari, A. K. Oral and dermal toxicity of alkenones extracted from Isochrysis species. Frontiers in Bioscience-Landmark, 25(5), (2020): 817–837, https://doi.org/10.2741/4836.Isochrysis is commercially available marine algae used for animal feed, human nutrient supplements, and biodiesel. The Isochrysis species is one of five genera of haptophytes that produces unique, long-chain lipids known as alkenones that are promising new ingredients for green cosmetics, personal care products and pharmaceutical delivery. However, there is a lack of toxicity data for alkenones in animals, thus limiting their use in humans. In this study, we performed acute oral, acute dermal, and repeated 28-day dermal toxicity studies, using female SAS Sprague Dawley Rats. Our behavioral studies indicated that the specific alkenones had no overt behavioural effects at oral doses up to 4000 mg/kg. In the acute and chronic dermal toxicity studies, the alkenones produced less irritation and did not significantly damage the skin based on the Draize skin reaction scale and trans-epidermal water loss readings compared to the positive control, 1% sodium lauryl sulfate. Overall, our results indicated that alkenones are safe in Sprague Dawley rats, suggesting that they could be used for both oral and dermal formulations, although additional studies will be required.This work was supported by the Marine Biological Laboratory Woods Hole Oceanographic Institute (WHOI) under grant (N-126665-01, 2017), Washington Research Foundation, and University of Toledo start-up funding under a grant (F110760) to A.K.T. The authors declare no conflict of interest

DNA Extraction Method Development for Ocular Tissues

Purpose: DNA extraction kits are traditionally developed to work with liquid tissues such as blood, saliva, and swabs, but some have been proposed to work with solid tissues. Somatic variation in cancers can be important for tumor subtyping and treatment guidance, including ocular tumors. Additionally, epigenetic marks such as 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are tissue-specific and change in disease states, particularly evident in diabetic retinopathy and age-related macular degeneration. Commercial DNA extraction kits are available from several vendors, but the various kits have different strengths and weaknesses, and the removal of PCR inhibitors will vary with each kit. This project investigates the yield and purity of DNA from ocular tissues using commercial DNA extraction kits. Methods: Cornea, neural retina, RPE/choroid layer, optic nerve, and capsular bag were collected and aliquoted into 15 mg aliquots. Extractions were performed using the following kits: DNEasy Blood and Tissue Kit (Qiagen;), GeneJET Genomic DNA Purification Kit (ThermoFisher Scientific), Monarch HMW DNA Extraction Kit for Tissue (New England Biosciences), and genomicPrep Mini Spin Kit (Cytiva). DNA was quantified using the Qubit Fluorometer and molecular weight was checked by agarose gel. Several more kits are currently being tested. Results: All four kits yielded high molecular weight DNA (above 20 kbp). The Monarch HMW kit yielded DNA with significantly higher molecular weights. The DNA yields per milligram of tissue were highest using the DNEasy Blood and Tissue Kit for optic nerve, neural retina, and RPE/choroid. The yield was highest for the cornea using the genomicPrep Mini Spin Kit. Only the genomicPrep Mini Spin Kit yielded sufficient DNA for quantification from the capsular bag, and total yields were minimal (600 ng or less). Additional kits are currently being tested, but initial results indicate that several commercial kits will be sufficient for DNA extraction of ocular tissues. Further work is needed to purify epithelial cells and stem cells from the intraocular lens. Conclusions: Of the kits tested, all are sufficient to obtain significant amounts of DNA from all ocular tissues aside from the capsular bag. The Monarch HMW yielded the highest molecular weight, but significantly lower quantities of DNA than the other kits, indicating that it may not be ideal for most purposes. Protocol development for the capsular bag is still underway

Non-Traditional Presenting Grade II Brain Meningioma: A Case Study

Meningioma is a relatively common form of cancer, occurring in approximately 97 out of 100,000 individuals. Although it arises from the meninges surrounding the central nervous system (CNS) rather than from neurons, it is classified with CNS tumors due to overlapping symptoms caused by compression of nerves and vessels in the head. Extracranial metastasis is rare, at less than 1%, and correlates with reduced survival rates

Results of the Second SIGMORPHON Shared Task on Multilingual Grapheme-to-Phoneme Conversion

Grapheme-to-phoneme conversion is an important component in many speech technologies, but until recently there were no multilingual benchmarks for this task. The second iteration of the SIGMORPHON shared task on multilingual grapheme-to-phoneme conversion features many improvements from the previous year's task (Gorman et al. 2020), including additional languages, a stronger baseline, three subtasks varying the amount of available resources, extensive quality assurance procedures, and automated error analyses. Four teams submitted a total of thirteen systems, at best achieving relative reductions of word error rate of 11% in the high-resource subtask and 4% in the low-resource subtask

The Massive and Distant Clusters of WISE Survey VI: Stellar Mass Fractions of a Sample of High-Redshift Infrared-selected Clusters

We present measurements of the stellar mass fractions ($f_\star$) for a sample of high-redshift ($0.93 \le z \le 1.32$) infrared-selected galaxy clusters from the Massive and Distant Clusters of WISE Survey (MaDCoWS) and compare them to the stellar mass fractions of Sunyaev-Zel'dovich (SZ) effect-selected clusters in a similar mass and redshift range from the South Pole Telescope (SPT)-SZ Survey. We do not find a significant difference in mean $f_\star$ between the two selection methods, though we do find an unexpectedly large range in $f_\star$ for the SZ-selected clusters. In addition, we measure the luminosity function of the MaDCoWS clusters and find $m^*= 19.41\pm0.07$, similar to other studies of clusters at or near our redshift range. Finally, we present SZ detections and masses for seven MaDCoWS clusters and new spectroscopic redshifts for five MaDCoWS clusters. One of these new clusters, MOO J1521+0452 at $z=1.31$, is the most distant MaDCoWS cluster confirmed to date.Comment: Accepted to Ap