The Role of Fluorescence and Human Factors in Quantitative Transdermal Blood and Tissue Analysis Using NIR Raman Spectroscopy

This research is part of an ongoing project aimed at the application of combined near infrared (NIR) Raman and fluorescence spectroscopy to noninvasive in vivo blood analysis including but not limited to glucose monitoring. Coping with practicalities of human factors and exploring ways to obtain and use knowledge gained about autofluorescence to improve algorithms for blood and tissue analysis are the general goals of this research. Firstly, the study investigated the various sources of human factors pertinent to our concerns, such as fingerprints, turgor, skin hydration and pigmentation. We then introduced specialized in vivo apparatus including means for precise and reproducible placement of the tissues relative to the optical aperture, i.e., the position detector pressure monitor (PDPM). Based on solid instrumental performances, appropriate methodology is now provided for applying and maintaining pressure to keep surface tissues immobile during experiments while obtaining the desired blood content and flow. Secondly, in vivo human fingertip skin autofluorescence photobleaching under 200 mW 830 nm NIR irradiation is observed and it is characterized that: i) the majority of the photobleached fluorescence originates from static tissue not blood, ii) the bleaching (1/e point) occurs in 101-102 sec timescale, and also iii) a photobleached region remains bleached for at least 45 min but recovers completely within several hours. A corresponding extensive but not exhaustive in vitro systematic study narrowed down the major contributors of such fluorescence and bleaching to collagen, melanin, plasma and hemoglobin: two major static tissue constituents and two major blood proteins. Thirdly, we established that measuring the inelastic and elastic emissions simultaneously leads to a sensitive probe for volume changes of both red blood cells and plasma. An algorithm based on measurements obtained while performing research needed for this thesis, as well as some empirical calibration approaches, was presented. The calibrated algorithm showed real potential to track hematocrit variations in cardiac pulses, centrifugal loading, blood vessel blockage using tourniquet, and even during as subtle an occurrence as in a Valsalva maneuver. Finally, NIR fluorescence and photochemistry of pentosidine, a representative of the advanced glycation endproducts (AGEs) which accumulate with age and hyperglycemia, was studied. The results indicate that oxygen plays a pivotal role in its photobleaching process. We hypothesized and offered proofs showing that pentosidine is a 1O2 sensitizer that is also subject to attack by the 1O2 resulting in the photobleaching that is observed when probing tissue using NIR. The photobleaching reaction is kinetically first order in pentosidine and ground state oxygen, and in vivo effectively first order with NIR irradiation also

Transcriptional Profiling of Plasmodium falciparum Parasites from Patients with Severe Malaria Identifies Distinct Low vs. High Parasitemic Clusters

Background: In the past decade, estimates of malaria infections have dropped from 500 million to 225 million per year; likewise, mortality rates have dropped from 3 million to 791,000 per year. However, approximately 90% of these deaths continue to occur in sub-Saharan Africa, and 85% involve children less than 5 years of age. Malaria mortality in children generally results from one or more of the following clinical syndromes: severe anemia, acidosis, and cerebral malaria. Although much is known about the clinical and pathological manifestations of CM, insights into the biology of the malaria parasite, specifically transcription during this manifestation of severe infection, are lacking. Methods and Findings: We collected peripheral blood from children meeting the clinical case definition of cerebral malaria from a cohort in Malawi, examined the patients for the presence or absence of malaria retinopathy, and performed whole genome transcriptional profiling for Plasmodium falciparum using a custom designed Affymetrix array. We identified two distinct physiological states that showed highly significant association with the level of parasitemia. We compared both groups of Malawi expression profiles with our previously acquired ex vivo expression profiles of parasites derived from infected patients with mild disease; a large collection of in vitro Plasmodium falciparum life cycle gene expression profiles; and an extensively annotated compendium of expression data from Saccharomyces cerevisiae. The high parasitemia patient group demonstrated a unique biology with elevated expression of Hrd1, a member of endoplasmic reticulum-associated protein degradation system. Conclusions: The presence of a unique high parasitemia state may be indicative of the parasite biology of the clinically recognized hyperparasitemic severe disease syndrome

Procurement specifications report. IMBLS phase B-4

Procurement specifications to provide vendors of space systems with supporting information to accurately price the selected major buy items are illustrated. In performing this task, rigid constraints on specifications and drawing details are avoided beyond those necessary to define basic requirements. Described are digital processing equipment, mass spectrometer, body mass measuring device, sensors, bio-belt power source, vision tester and instrumentation for a biochemical station

Towards real-time monitoring of bacterial cultures without the need for physical sampling: elastic scattering, fluorescence and Raman spectroscopy of Escherichia coli cultures.

The first part of this dissertation pertains to the fringe analysis of a hydration layer that forms spontaneously when biofilms dry. This layer at optical thickness ˂ 20 µm is approximately 1-2 orders of magnitude thinner than the biofilm thickness as measured by confocal Raman microscopy and confocal fluorescent microscopy. Drying/rehydration experiments performed on films withstood multiple cycles, returning to the same optical thickness proving their robust nature. The strength of a distinct water peak (1451 nm) in addition to others, reflects the thickness of the hydration layer. Confocal Raman microscopy showed that biofilms are chemically very similar to pure alginate (synthetic) films. This shows that spontaneous formation of the hydration layer is a chemical process verses a biological process. The second chapter presents real-time, noninvasive, quantitative analysis of bacterial cultures for cell count and glucose uptake using turbidity corrected spectroscopy and Raman. We hypothesize that a Raman feature we ascribe to “biomass” (~1060 cm-1) i.e. a υ(C-O-C) asymmetric stretch or (C-C) stretch, and a glucose peak (~1140 cm-1) i.e. the υ(C–O) and/or υ(C–C) stretch allow for the real-time monitoring of cell count and nutrient depletion. We calibrated this technique to be backward compatible with OD600 for characterizing culture number density. The method involves irradiating a culture in fluid medium (LB/MM) in a quartz cuvette using a NIR laser (785 nm) and collecting all backscattered light from the cuvette. This approach may be useful in a broad range of academic/industrial applications that utilize bacterial cultures

Micro/Nano Devices for Blood Analysis, Volume II

The development of micro- and nanodevices for blood analysis continues to be a growing interdisciplinary subject that demands the careful integration of different research fields. Following the success of the book “Micro/Nano Devices for Blood Analysis”, we invited more authors from the scientific community to participate in and submit their research for a second volume. Researchers from different areas and backgrounds cooperated actively and submitted high-quality research, focusing on the latest advances and challenges in micro- and nanodevices for diagnostics and blood analysis; micro- and nanofluidics; technologies for flow visualization and diagnosis; biochips, organ-on-a-chip and lab-on-a-chip devices; and their applications to research and industry

A study of the collection and preservation of biological specimens during space flight for post-flight analysis Final report

Collection and preservation of blood, urine, and feces and sweat samples obtained during space flight

DEVELOPMENT AND APPLICATION OF NOVEL PHYSIOLOGICAL MRI METHODS TO IMAGE CHANGES IN OXYGENATION

This dissertation details the application of novel MRI methods (VASO and APT MRI) to acute stroke as well as the work to develop a novel MRI technique to image oxygenation in the brain

Erythrosensors Cellular Characterization

For diabetics, continuous glucose monitoring, and the resulting tighter control of glucose levels, ameliorates serious complications from hypoglycemia and hyperglycemia. Today, diabetics measure their blood glucose levels multiple times a day by finger pricks, or use implantable monitoring devices. Still, glucose and other analytes in the blood fluctuate throughout the day and the current monitoring methods are invasive, immunogenic, and/or present biodegradation problems. Using carrier erythrocytes loaded with a fluorescent sensor, we seek to develop a biodegradable, efficient, and potentially cost effective method for long-term monitoring of blood analytes. We aim to reintroduce sensor-loaded erythrocytes to the bloodstream and conserve the erythrocytes lifetime of 120 days in the circulatory system. Here, the efficiency of two loading procedures is compared. Hypotonic dilution employs hypotonic buffer to create transient pores in the erythrocyte membrane, allowing dye entrance and a hypertonic buffer to restore tonicity. Electroporation relies on controlled electrical pulses that results in reversible pores formation to allow cargo entrance. As part of the cellular characterization of loaded erythrocytes, size and hemoglobin content was evaluated. Cell recovery and fluorescence per cell measurements also render optimal loading conditions. Furthermore, AFM and confocal microscopy protocols were implemented to evaluate morphological changes induced by hypotonic dilution. The development of a suitable protocol to engineer carrier erythrocytes has profound and lasting implications in the erythrocytes’ lifespan and sensing capabilities

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 171

This bibliography lists 186 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1977

Biomedical and Human Factors Requirements for a Manned Earth Orbiting Station

This report is the result of a study conducted by Republic Aviation Corporation in conjunction with Spacelabs, Inc.,in a team effort in which Republic Aviation Corporation was prime contractor. In order to determine the realistic engineering design requirements associated with the medical and human factors problems of a manned space station, an interdisciplinary team of personnel from the Research and Space Divisions was organized. This team included engineers, physicians, physiologists, psychologists, and physicists. Recognizing that the value of the study is dependent upon medical judgments as well as more quantifiable factors (such as design parameters) a group of highly qualified medical consultants participated in working sessions to determine which medical measurements are required to meet the objectives of the study. In addition, various Life Sciences personnel from NASA (Headquarters, Langley, MSC) participated in monthly review sessions. The organization, team members, consultants, and some of the part-time contributors are shown in Figure 1. This final report embodies contributions from all of these participants