We have investigated various optical fiber probes for remote Raman scattering measurements in tissues. The diameter of the optical fiber probe was kept below 3 mm in order to be able o fit into the working channel of existing endoscopes for in vivo measurements inside the human body. Different designs were tested to examine the best possible arrangement of the required optical. The main problems encountered arising from the Raman scattering and fluorescence emission inside the fiber itself are discussed and possible approaches to overcome the limitations are addressed.

The feasibility of using Raman spectroscopy to monitor the concentration of chemical species in a bioreactor has been examined. Successful operation of a bioreactor requires that nutrients and metabolic waste products be maintained within narrow ranges, and it is, therefore, important to provide accurate, reliable and timely measurement of the composition in the reactor. Raman spectroscopy offers the possibility of real time simultaneous monitoring of molecular components present in the millimolar and higher concentration range. Work reported here has focused on four analytes: glucose, glutamine, lactic acid and ammonia. Measurements have been made with a spectrograph providing a spectral window for simultaneous measurement of about 1800 cm^-1 on a multichannel CCD detector. Most measurements were made with an argon ion laser emitting at 514.5 nm. Some measurements are reported with a solid state diode laser operating at 785 nm. Locally constructed inexpensive silica fiber-optic probes delivered the laser light and collected the scattered radiation. Spectra of the four analytes n buffer and reactor media have been obtained. Analytical curves have been constructed and limits of detection measured. Limits of detection in buffer media are about 1 mM. Results are reported for off-line measurements on material drawn from a bioreactor.

A Raman spectroscopy-based sensor is being developed for general anesthetics or the small organics. The sensor uses a selectively-absorbent polymer to concentrate the analyte and thus produce a higher spectral signal intensity. This helps counteract the inherently low signal characteristic of Raman spectroscopic analyses. Waveguides have been fabricated from a commercially available methacrylate-functional silicone. Using diethoxyacetophenone photoinitiator and a silanizing agent to enhance adhesion, silicone waveguides have been photopolymerized onto fused silica substrates. Linear waveguides 200 micrometers wide and 240 micrometers thick exhibited attenuations on the order of 1.2 dB/cm, as determined by measurements of Raman silicone peak intensity down the length of the waveguide. Studies with liquid deuterochloroform in silicone oil yielded a detection limit of 0.092 MAC, where MAC, or minimum alveolar concentration, is a unit of measure for general anesthetics. Finally, partitioning of gaseous deuterochloroform into these waveguides produced a clearly discernible peak.

A new method was presented in this paper to measure temperature and an optical fiber based sensor was fulfilled by this way. The sensor was miniaturized, flexible, low cost, lack of interference of electromagnetic, biocompatibility and higher resolution, short response time. It can be used in many aspects, especially in the field of biomedicine.

An instrument designed for physiological monitoring should be relatively inexpensive, take readings rapidly and be able to discriminate optical signals due to specific chromophores. A cw, broadband, multifiber system can potentially meet these requirements. The use of a steady- state light source rather than making time-resolved or frequency-domain measurements means that the system is relatively inexpensive. Simultaneous detection of signals from multiple optical fibers means that multiple measurements can be made simultaneously. By making broadband measurements it is possible to discriminate amongst the many chromophores which contribute the optical signal. We have developed a cw, broadband, multifiber system and are testing it in vivo. A possible application is noninvasive, optical monitoring of the brain which has the potential to be a real-time, noninvasive method for clinical monitoring as well as being a technique for studying fundamental aspects of brain function.

A compact fiber-optic sensing system that features all-fiber optical design and semiconductor-laser excitation has been developed and tested. A 2X2 fiber coupler directs the input light to the SMA connected sensing fiber tip and the fluorescent signal back to a CCD fiber spectrophotometer. In this system, the fluorescent signal is confined in the fiber system so the signal-to-noise ratio is greatly improved and the system can be operate in ambient light conditions. The utilization of a red laser diode has reduced the background signal of non-essential biomolecules. The fluorescent dye used is Cy5, which has an excitation wavelength of 650 nm and a fluorescent center wavelength of 680 nm. To illustrate the biosensor's diagnostic capabilities, a sandwich immunoassay to detect Salmonella is presented. Tapered fiber tips with different shapes and treatments were studied and optimized. An enhancement system employing ultrasonic concentration of target particles has also been developed and applied to the detection of Salmonella. The immunoassay was conducted in a test chamber that also serves as an ultrasonic standing-wave cell and allows microspheres to be concentrated in a column along the fiber probe. The system demonstrates broad promise in future biomedical application.

Commercial fiberoptic thermometers have been available for a number of years. The early products were unreliable and high in price. However, the continuing effort in the development of new sensing techniques along with the breakthroughs made in many areas of optoelectronics in recent years have made the production of cost competitive and reliable systems feasible. A fluorescence decay time based system has been demonstrated to successfully meet both cost and performance requirements for various medical applications. A very critical element to the success of this low cost and compact fiberoptic thermometer is the fluorescent sensor material. The very high quantum efficiency, the operating wavelengths, and the temperature sensitivity helped significantly in simplifying the design requirements for the optics and the electronics. The one to eight channel unit contains one to eight modules of a simple optical assembly: an LED light source, a small lens, and a filter are housed in an injection molded plastic container. Both the electronics and the optics reside on a small printed circuit board of approximately 6 inches by 3 inches. This system can be packaged as a stand alone unit or embedded in original manufacturer equipment.

We report here on the development of a sol-gel based fiber optic sensor to monitor local blood pH. These sensors are being developed for invasive medical applications; that is, they will be coaxially threaded through a catheter beyond an occlusion in the vascular system. The fiber optic pH sensor design was based on the immobilization of a pH sensitive dye, seminaphthorhodamine-1 carboxylate, onto the tip or surface of an optical fiber using the sol-gel method. The fiber optic pH sensor was tested in phosphate buffer saline and human whole blood using a miniature fluorimeter system. Linear responses were obtained in blood in the pH range 6.7 to 8.0, which demonstrates potential for use for in vivo sensing.

A portable, compact device for measuring blood gases by using the fluorescence decay time as the information carrier is presented. The instrument is based on solid state technology only, thus using LEDs for excitation and a photodiode as detector. A capillary coated on its inner surface with different sensing membranes serves as a sample compartment and an optical sensor element simultaneously. Furthermore, due to inhomogeneous waveguiding in the capillary walls, only the fluorescent light is guided. Technical details of the electronic circuit, the optical design and the instrumental performance will be discussed.

A new reflectance pulse oximeter sensor for lower arterial oxygen saturation (Sa)₂) measurement has been designed and evaluated in animals prior to clinical trials. The new sensor incorporates ten light emitting diode chips for each wavelength of 730 and 880 nm mounted symmetrically and at the radial separation distance of 7 mm around a photodiode chip. The separation distance of 7 mm was chosen to maximize the ratio of the pulsatile to the average plethysmographic signal level at each wavelength. The 730 and 880 wavelength combination was determined to obtain a linear relationship between the reflectance ratio of the 730 and 880 nm wavelengths and Sa)₂. In addition to these features of the sensor, the Fast Fourier Transform method was employed to compute the pulsatile and average signal level at each wavelength. The performance of the new reflectance pulse oximeter sensor was evaluated in dogs in comparison to the 665/910 nm sensor. As predicted by the theoretical simulation based on a 3D photon diffusion theory, the 730/880 nm sensor demonstrated an excellent linearity over the SaO₂ range from 100 to 30 percent. For the SaO₂ range between 100 and 70 percent, the 665/910 and 730/880 sensors showed the standard error of around 3.5 percent and 2.1 percent, respectively, in comparison to the blood samples. For the range between 70 and 30 percent, the standard error of the 730/880 nm sensor was only 2.7 percent, while that of the 665/910 nm sensor was 9.5 percent. The 730/880 sensor showed improved accuracy for a wide range of SaO₂ particularly over the range between 70 and 30 percent. This new reflectance sensor can provide noninvasive measurement of SaO₂ accurately over the wide saturation range from 100 to 30 percent.

Detection of endogenous carbon monoxide content in breath with tunable diode lasers (TDL) was proposed for noninvasive monitoring of rapid blood pH variation. Applied approach is based on high sensitivity of the haemoglobin and myoglobin affinity for CO to blood pH value and an ability to detect rapidly small variations of CO content in expired air. Breath CO absorption in 4.7 micrometers spectral region was carefully measured using PbSSe tunable diode laser that can provide 1 ppb CO concentration sensitivity and 10 s time constant. Applied TDL gas analyzer was used to monitor expired air of studied persons in physiological tests including hyperventilation and physical load. Simultaneous blood tests were conducted to demonstrate correlation between blood and breath chemical parameters.

In this paper we report on the experimental setup and the performances of a fluorescence lifetime imaging system designed by the authors for cancer detection. The experimental apparatus relies on a CCD video camera coupled to a light intensifier and on a pulsed laser. Two or more fluorescence images are acquired within suitable time windows at different delays, with respect to the excitation pulses. The images are processed using matrix algorithms implemented in the fast processor of an advanced frame grabber; then, the resulting lifetime map is displayed in pseudocolor or gray shade images. The instrumentation is fully computer controlled and the whole process takes about 1 second per lifetime image. Using a faster processor this time could be easily reduced to some milliseconds for true real time measurements. The system has been successfully applied to detect experimental tumors in mice sensitized with hematoporphyrin derivative, which is a clinically approved photosensitizing drug.

Indo-1 and Mag-indo-1 are well known fluorescent probes which consist in two different cages of complexation covalently bound to the same fluorophor. The ionic rap of Indo-1 fit perfectly the size of the calcium ion and its sensitivity is well adapted to the basal concentration of calcium ion in the cytoplasm. Although Mag-indo-1 was designed to complex magnesium, it has been demonstrated that it is a chelator more efficient for calcium than for magnesium. Moreover, it has been suggested recently that Fura 2, Indo-1, and Mag-indo-1 might be partially located inside the membranes of intracellular organelles where the concentration of calcium is expected to be far higher than that of magnesium. All these data question again the use of the simple spectrofluorimetric methods to quantify the cytoplasmic concentration in magnesium. Our studies in solution have confirmed that Mag-indo-1 is a potent chelator for calcium and also demonstrated that the fluorescence spectrum of the calcium-bound Mag-indo-1 is quite similar to that of magnesium-bound Mag-indo-1. Experiments have been carried out with 3T3 cells to quantify the amount of Mag- indo-1 entrapped in the intracellular membranes and its consequences on the monitoring of the intracytoplasmic concentration of magnesium.

Signal amplification using labels should be replaced by a technique monitoring the biochemical binding event directly. The use of a ligand coupled to an artificial gated membrane ion channel is a new promising strategy. Binding of protein- or DNA/RNA-analytes at ligand modified peptide channels results in an on/off-response of the channel current due to channel closure or distortion. The sensor consists of stable transmembrane channels with a ligand bound covalently at the peptide channel entrance, a sensor chip with a photostructurized hydrophobic polymer frame, a hydrophilic ion conducting membrane support, a lipid membrane incorporating the engineered ion channels, and a current amplifier or a sensitive fluorescence monitor. Detection of channel opening or closure can ether be obtained by directly monitoring membrane conductivity or a transient change of pH or ion concentration within the membrane compartment. This change can be induced by electrochemical or optical means and its decay is directly correlated to the permeability of the membrane. The ion concentration in the sub membrane compartment was monitored by incorporation of fluorescent indicator dyes. To obtain the stable sensor membrane the lipid layer had to be attached on a support and the floating of the second lipid membrane on top of the first one had to be prevented. Both problems do not occur using our new circular C44-C76 bolaamphiphilic lipids consisting of a long hydrophobic core region and two hydrophilic heads. Use of maleic ester-head groups enabled us to easily modify the lipids with amines, thioles, alcohols, phosphates, boronic acid as well as fluorescent dyes. The properties of these membranes were studied using LB and fluorescence techniques. Based on this detection principle miniaturized sensor chips with significantly enhanced sensitivity and large multi analyte arrays are under construction.

In fluorescence labelled immunosensing the discrimination of labels remaining in the bulk solution from labels bound to the analyte at the sensor surface is a basic optical problem. It is shown that application of surface enhanced fluorescence at a layer of noble metal nano-particles can increase the surface-to-background signal ratio. We explain the enhancement mechanism by an electrodynamic model and discuss the interaction between metal particle and fluorophore for the excitation and emission process. We show the principal guidelines for optimization of that processes. We find that the obtained discrimination power increases with decreasing intrinsic quantum efficiency of the fluorophore, suggesting the application of new classes of labels, namely low-quantum efficiency fluorophores. This theoretical finding is shown by a practical model experiment.

This work refers to the development of an equipment for computer assisted digital dermatology as a basis for the creation of active support systems for early diagnosis of melanotic disease. It is based on a digital epiluminescence technique, taking advantage of polarized lith guided by optical fibers. In the purpose to discriminate between malignant and benign melanocytic lesions, several dermatoscopical features have been proposed by different research groups. Nevertheless many are the attempts to reach a reliable and objective classification procedure. We adopt, as reference, the approach used by Stanganelli and Kenet. Through a bioengineering analysis we can organize reference grids that offer the possibility to extract the maximum information content from dermatological data. The classification takes into account the spread and intrinsic descriptors and corresponds to the best operative descriptio. Therefore these grids ar the more suitable tools for applications which require active support systems for diagnosis. In fact, it is possible to obtain quantitative evaluations too. We propose a method based on geometrical synthetical descriptors. All that permits a reliable early diagnosis of melanotic disease and to follow its evolution in time.

In most operation theaters today planning is done using pre- operatively gathered data, such as CT, MRI, or ultrasound (US). This data can become useless in cases such as lesion removal in brain, where dura opening and other preparations cause tissue shifting. A possibility to greatly increase accuracy in an ongoing operation is the use of 3D ultrasonography. The sequences of intra-operatively obtained 2D US-slices can be transformed into 3D, matched to previously acquired data, and be used to adapt the surgical planning to the current situation. The matching is done after standard image processing procedures have been applied to the 2D US data, this data has been injected into a 3D data cube, segmentation, and topological differentiation have taken place. This requires the usage of highly sophisticated graphics workstations. The objective is to create a framework in which surgeons and/or robotic neuronavigators can be informed and guided with the newest and most precise information possible during an operation.

Surgery is progressing rapidly into a less invasive mode, shorter hospital stays, less pain, lower morbidity and mortality. Perhaps, no surgical specialty has benefitted more from this advancing technology then neurosurgery. Refinements in magnification, illumination and instrumentation have propelled neurosurgery into a new era. The advent of the operating microscope led to numerous instrumentation innovations. Various types of lasers were adapted to the microscope. The ultrasonic aspirator was added. Stereotactic neurosurgery is moving into the ultrasonic guidance and frameless stereotactic systems. Percutaneous and endoscopic neurosurgery are more recent advances.

The method of laser-involved therapy can be classified as the following: (1) intravascular low level He-Ne laser irradiation therapy; (2) light-oxygen-blood therapy; (3) light-oxygen-blood therapy. The key of laser-involved therapy is the proper wavelength light. The use of energy in laser-involved therapy is different from that in laser acupuncture. Of all kinds of light-involved therapy, oxygen has direct influence on the curative effect. Oxygen can be thought as the carrier of laser energy. Having absorbed the photon, the oxygen get excited and reaches every part of the organism through blood circulation, which promotes physiological and biochemistry reaction and therefore improves the metabolism.

We compare the application accuracy of using semi-invasive fiducial markers to the Zamorano-Dujovny stereotactic ring for interactive localization of intracranial lesions. A phantom was mounted with the standard ring and also implanted with a frameless marker system which randomly distributed markers on the surface of the phantom. The target point was digitized and the coordinates were recorded and compared with reference points. Nineteen patients with intracranial lesions, chosen in random fashion, underwent a frameless stereotactic approach for tumor resection. Five semi-invasive markers were placed on the patients' skulls under local anesthesia. The coordinate of each fiducial marker was recorded in a file as the reference. The tip of each semi-invasive fiducial marker was digitized to achieve a frameless transformation matrix, and the special points on the A Zamorano-Dujovny ring were digitized to achieve a frame-based transformation matrix. The differences from the reference points were used as the deviation from the 'true point'. The mean square root was calculated to show the sum of vectors. A paired t-test was used to analyze results. The results of the phantom showed that the registration error of the frame-based system was 3.42 +/- 0.22 mm and in the frameless system was 1.01 +/- 0.63 mm. The mean showed that the mean square root of the frame-based system as 3.77 +/- 2.16 mm and of the frameless system was 2.25 +/- 1.75 mm. These preliminary results showed that the frameless semi- invasive fiducial can provide more accurate localization for may procedures. The motion of the ring after computed tomographic scan is the main reason for the errors in the frame-based system.

This paper introduces techniques for the extraction of anatomical structures from magnetic resonance (MR) images of the head. The goal of the work is to extract features that are useful for registration of different modalities of tomographic datasets of a patient. These features must therefore be present in multiple modalities of the datasets. Three such features that can be extracted are the location of the eyes, the longitudinal fissure, and the lateral ventricles. In this paper, we present our methods for extracting these features. The techniques exploit geometric shape characteristics to aid in the extraction process, chiefly through the use of Hough-based accumulations for location of the eyes and longitudinal fissure. An approach consisting of volume-growing followed by a locally adaptive histogramming is used for extraction of the ventricles.

Talairach's Co-Planner Stereotactic Atlas of the human brain (Talairach's) has been widely used as a guide for stereotactic neurosurgery. Using this atlas many research groups including ours have built computer digitized 3D volume atlases. Atlas construction of this kind is a complicated process. Accuracy and consistency of resulting volumes are uncertain. There are three different series in this version of Talairach's: axial, sagittal, and coronal. Quantitative tests of consistency among these series have not been designed nor performed. Our objective is to study the consistency of 3D volume atlases generated rom the three different series of Talairach's atlas. 28 axial images, 38 coronal images and 36 sagittal images from the atlas are scanned into the computer. Images are re-aligned and normalized based on existing grids that appear on the atlas. Three 'brain volume' atlases were generated from the corresponding series. Tri-linear interpolation, segmentation, multi-planner reconstruction, and 3D surface rendering tools were used to visualize and analyze 3D structures. Analysis of consistency was based on shape observances, area values, and volume values. Structures in the thalamus, pallidus, and caudate were segmented from three volume atlases for the study. Our results indicate that volume atlases generated rom axial, coronal, and sagittal series of Talairach's stereotactic atlas are spatially consistent with relative degree of accuracy, and therefore is reliable. these data can be used to make computer digitized 3D volume atlases for stereotactic surgery.

Our objective is to offer online real-tim e intelligent guidance to the neurosurgeon. Different from traditional image-guidance technologies that offer intra-operative visualization of medical images or atlas images, virtual brain counseling goes one step further. It can distinguish related brain structures and provide information about them intra-operatively. Virtual brain counseling is the foundation for surgical planing optimization and on-line surgical reference. It can provide a warning system that alerts the neurosurgeon if the chosen trajectory will pass through eloquent brain areas. In order to fulfill this objective, tracking techniques are involved for intra- operativity. Most importantly, a 3D virtual brian environment, different from traditional 3D digitized atlases, is an object-oriented model of the brain that stores information about different brain structures together with their elated information. An object-oriented hierarchical hyper-voxel space (HHVS) is introduced to integrate anatomical and functional structures. Spatial queries based on position of interest, line segment of interest, and volume of interest are introduced in this paper. The virtual brain environment is integrated with existing surgical pre-planning and intra-operative tracking systems to provide information for planning optimization and on-line surgical guidance. The neurosurgeon is alerted automatically if the planned treatment affects any critical structures. Architectures such as HHVS and algorithms, such as spatial querying, normalizing, and warping are presented in the paper. A prototype has shown that the virtual brain is intuitive in its hierarchical 3D appearance. It also showed that HHVS, as the key structure for virtual brain counseling, efficiently integrates multi-scale brain structures based on their spatial relationships.This is a promising development for optimization of treatment plans and online surgical intelligent guidance.

Computer-assisted surgery technology relies heavily on multi-modality medical image and multimedia information. To systematically manage this information is a challenging task due to fast information growth and geographical expansion of the computer-assisted surgery (CAS) field. After many years developing image-guided surgery techniques, types and media of information are rapidly growing. CAS can grow from a traditional single suite containing only one operating room with a workstation, to a distributed CAS center that can include multiple operating rooms and a control room in order to distribute CAS service throughout a large medical center or an entire metropolitan area. This expansion increases the sophistication of information management or CAS significantly. This paper first identifies different types of multi-modality information and multimedia information involved in the CAS field, and then presents strategies and methods of managing this information. We discuss our CAS system developed at Wayne State University. Detroit Medical Center as a typical example.

This paper reports our preliminary investigation of developing an optically coupled CCD x-ray imaging system for digital x-ray fluoroscopy. The limitations of an image intensifier, TV camera based fluoroscopy are discussed. The contrast sensitivity and contrast-detail deductibility of a lens coupled CCD prototype was compared with an image- intensifier, TV camera based fluoroscopy. The results indicated that a well designed coupled CCD can be x-ray quantum noise limited, and it offers better contrast and resolution than the investigated image-intensifier, TV camera fluoroscopy systems.

Recent advances in imaging spectroscopy provide the opportunity for mapping the oxygen saturation of blood in skin with high accuracy, large spatial coverage, small spatial resolution, and high update rate. A four-wavelength algorithm, specifically designed to compute the oxygen saturation of hemoglobin, in vivo, from a set of narrow-band visible images was used to analyze various skin tissue disorders. To illustrate the spatial capability of this algorithm, mapping of the oxygen saturation of normal skin, hypoxic tissue and various skin lesions was performed using reflectance spectroscopy, demonstrating the spatial resolution of the images of blood oxygen in the tissues. To explore the accuracy of the algorithm, Monte-Carlo modeling was used to generate reflectivities of skin with known parameters. These reflectivities were used to evaluate the limiting effects of quantization error, photon noise, and finite filter bandwidth on the accuracy of the algorithm. In addition, a signal-to-noise analysis was performed to determine the illumination requirements. It is shown that accurate maps of blood oxygen can be produced with good spatial resolution.

The pseudo-random modulation/near IR sensor (PRM/NIR Sensor) is a low cost portable system designed for time-resolved tissue diagnosis, especially hematoma detection in the emergency care facility. The sensor consists of a personal computer and a hardware unit enclosed in a box of size 37 X 37 X 31 cm³ and of weight less than 10 kg. Two pseudo-random modulated diode lasers emitting at 670 nm and 810 nm are used in the sensor as light sources. The sensor can be operated either in a single wavelength mode or a true differential mode. Optical fiber bundles are used for convenient light delivery and color filters are used to reject room light. Based on a proprietary resolution- enhancement correlation technique, the system achieves a time resolution better than 40 ps with a PRM modulation speed of 200 MHz and a sampling rate of 1-10 Gs/s. Using the prototype sensor, phantom experiments have been conducted to study the feasibility of the sensor. Brain's optical properties are simulated with solutions of intralipid and ink. Hematomas are simulated with bags of paint and hemoglobin immersed in the solution of varies sizes, depths, and orientations. Effects of human skull and hair are studied experimentally. In animal experiment, the sensor was used to monitor the cerebral oxygenation change due to hypercapnia, hypoxia, and hyperventilation. Good correlations were found between NIR measurement parameters and physiological changes induced to the animals.

We report on the development of a method that records spatially dependent intensity patterns of polarized light that is diffusely backscattered from turbid materials. It is demonstrated that these intensity patterns can be used to differentiate between suspensions of cancerous and non- cancerous cells and to observe different metabolic cell processes.Our technique employs polarized light from a He-Ne laser, which is focused onto the surface of the scattering medium. A surface area of approximately 4 X 4 cm around the light input point is imaged through polarization- analysis optics onto a CCD camera. One can observe a manifold of intensity patterns by varying the polarization state of the incident laser light and changing the analyzer configuration to detect different polarization components of the backscattered light. Introducing the Mueller-matrix concept for diffusely backscattered light, a framework is provided to select a subset of measurements which comprehensively describe the optical properties of backscattering media.

Oblique incidence relfectometry is a simple and accurate method for measuring the absorption and reduced scattering coefficients of turbid media. We used this technique to deduce absorption and reduced scattering spectra from wavelength resolved measurements of the relative diffuse reflectance profile of white light. In this study we measured the absorption and reduced scattering coefficients of chicken breast in the visible with the oblique incidence probe oriented at 0, 30, 60, and 90 degrees relative to the muscle fibers. We found that the reconstructed optical properties varied with probe orientation. This experiment demonstrates (1) the application of oblique-incidence fiber- optic reflectometry to measurements on biological tissue and (2) the effect of structural anisotropy on optical properties.

The use of bio-chemiluminescence immunoassay (BL/CLI) technology for molecular and cellular characterization is rapidly evolving. The excellent selectivity of this method can be exploited to identify the presence and distribution of specific cells. Current work involves the advancement of the required methods and technologies for application to the analysis of vascular wall surfaces. In this effort, various enzyme-linked antibodies are being explored which can be directed to cell surface antigens producing a luminogenic reaction. To aid in the analysis of this light emission, a custom high resolution digital imaging system which couples a multi-megapixel CCD with a specially designed image intensifier is under development. This intensifier system has high spatial resolution and excellent sensitivity in the wavelength region of the candidate BL/CL emissions. The application of this imaging system to BL/CLI requires unique performance characteristics and specialized optical design. Component level electro-optical tests of the imaging system will be presented along with design considerations for an eventual catheter based instrument. Initial in vitro experiments focused on the performance limits of the optical system in discriminating candidate luminogenic reactions. The main objective of these tests is the identification of suitable enzyme catalyzed systems for ultimate application to in vivo vascular tissue and cell diagnosis.

3,4,5,6,16,17-Hexadehydro-16-(methoxycarbolyl)-19(alpha) - methyl-20(alpha) -oxyohimbanium (alstonine) is a fluorescent alcaloid which is known to stain tumor cells more efficiently than normal. The interactions between alstonine and biological macromolecules were first investigated to provide the rationale for preferential labelling. Molecular filtration and spectrosfluorometric techniques with different macromolecules and isopolynucleotides have demonstrated that binding occurs only in the presence of uridyl rings. For the binding affect only the fluorescence intensity of alstonine it can be assumed that it involves only the side chain of the fluorescent compound. The capability for preferential staining was verified in culture using SK-OV-3 cells and rat hepatocarcinoma cells as tumor cells and Mouse fibroblasts or rat liver cells as controls. Techniques of image analysis have demonstrated the efficiency of cellular labelling even in aggregates of rat hepatocarcinoma. These experiments lead the way to the detection of tiny tumors developed on thin visceral walls, using a fiber optic device.

In the last few years there have been a number of research papers on self-assemblies of molecules as 'advanced materials' or 'smart sensors'. The inspiration for this exciting research, without question, comes from the biological world, where, for example, the lipid bilayer of the cell membrane is the most important self-assembling system. Although the first report on self-assembled bilayer lipid membranes (BLMs) in vitro was published in 1962, interface science including surface and colloid science has been dealing with these interfacial self-assemblies of amphophilic molecules since Robert Hooke's time. In this communication, we present results of extensive study of physical chemical properties of two new membrane systems: metal and hydrogel supported bilayer lipid membranes. Several methods have been sued to investigate the properties of these metal supported s-BLMs and hydrogel supported salt- bridge sb-BLMs. With the electrostriction method we observed different behavior of the planar lipid bilayer on metal substrate. The obtained results gave possibility to choose optical properties of the support for constructing s-BLM- based biosensors. The capacitance relaxation method was used to determine the changes of dielectric relaxation times and showed different dynamic proprieties of lipids on the metal substrate and in free standing BLMs. Analysis of membrane current noise allowed the examination of the dynamic properties of supported BLMs. Examples of a number of practical applications of s-BLMs for the construction of a glucose sensor for biomedical use as well as applications of agar supported BLMs for determining several toxins will be presented.

Albumin is an important protein and its glycated form increases in diabetes mellitus and is partly responsible for the age related phenomena. We have, therefore, investigated the optical absorption and fluorescence spectra of glycated albumin along with a kinetic study by means of a proteolytic reaction. For this purpose, albumin was glycated by a conventional method and the optical absorption spectra were recorded for both the glycated and the native forms, from 240 nm to 400 nm and found that they were dominated by a strong peak at 280 nm which was followed by a long tail up to 300 nm for the native and 400 nm for the glycated protein. Non tryptophane fluorescence spectra of both glycated and native albumins in solid form were investigated and it was found that the general features of both spectra are similar. The spectra are dominated by a weak peak located at 450 nm and an intense broad peak at 550 nm. This peak is followed by a shoulder at 625 nm and then a long tail up to 800 nm. One of the major effects of glycation in this investigation is in their physical forms. Native albumin has a crystalline form while the glycated one has a conglomerate form. This effect can be easily visualized when the sample is examined with the help of a fluorescence microscope. This result is in accordance with the data obtained from electron microscopy. Thus, this quick and direct approach could identify the presence of the glycated protein and could provide information on the pathology of diabetes art an early stage.

Nitric Oxide is a simple gaseous compound which serves as a regulatory molecule in a number of physiological processes. Due to its biological role as a potent local vasodilator,there has been widespread interest in the therapeutic use of gaseous nitric oxide a selective pulmonary vasodilator. Our goal is the development of a sensor for the direct and continuous measurement of inhaled nitric oxide concentrations. This study evaluated the reversibility of potential sensing compounds upon reaction with nitric oxide. Previously, absorption spectroscopy was used to study the sensitivity of the Fe II, Fe III and oxygenated forms of three biologically active hemes known to rapidly react with NO: hemoglobin, myoglobin, and cytochrome-c. This study focused on the photo-reversibility of the hem's reaction with nitric oxide. Hemoglobin, myoglobin and cytochrome-c in the Fe III state reversibly reacted with nitric oxide. Hemoglobin and myoglobin in the Fe II state non-reversibly reacted with nitric oxide to form an unstable product. Cytochrome-c (FeII) does not react with nitric oxide. The oxy forms of hemoglobin and myoglobin react with nitric oxide to form their respective met forms, unreversible via photolysis. For all reversible reactions, photolysis was gradual and complete within five minutes.

In spite of the successful use of detergents for the solubilization of a number of membrane proteins, this approach has some restrictions. It is mainly due to difficulties in removing detergents from the proteins which can influence the structure and function of the isolated proteins and interfere with channel activity measurements under the reconstruction of the proteins into lipid bilayers. We have developed a method using ethanol for the extraction of membrane proteins. The dielectric constant of ethanol is between those of water and carbohydrates which aids it to penetrate into the membrane between protein and lipids. This decrease the binding of lipids to proteins and promotes protein solubilization. We have applied this approach to the isolation and reconstitution in lipid bilayer of the large subunit of the (Na⁺, K⁺)- ATPase from microsomes and from mitochondria: two Ca²⁺-channels, thermogenin and the K_ATP channel. The properties of these channels remained native.

The design of a proposed CCD mosaic concept for digital mammography uses a lead shied with through holes to reduce the patient exposure in regions of the mosaic where there are no CCDs. This shield also has an inherent advantage of reducing the amount of scattered x-rays. We examined the scatter-to-primary ratio dependency with aperture size above and below the breast and air gap distance between the CCD assembly and the bottom of the breast. These results are discussed in regards to the optimization of the CCD mosaic concept and theoretical calculations.

Commercially available orthopaedic implants used to replace a fractured or damaged radial head in the elbow are limited because the simplified axisymmetric design only approximates the normal bone anatomy. An implant that more closely approximates the normal anatomy of the radial head is likely to be superior to the ones of standard shapes and sizes. This paper provides a description of how reverse engineering technology is being used to replicate the geometry of the radial head from computer tomography imagery. Reverse engineering is the process of generating accurate 3D CAD models of free-form surfaces from measured coordinate data. In this application, shape information of the bone is extracted from CT images, translated into global coordinates, and transferred to a CAD software package in order to generate a solid model of the radial head region. The solid model is formed by creating contours from edge points, lofting these contours, and then joining the lofted contours. The tool-path for machining the implant device on a computer numerically controlled milling machine is generated from the solid model. The results of an experiment are presented in order to demonstrate the effectiveness of this approach to reverse engineering and manufacturing radial head replacements.

Sol-gel techniques have became very popular recently due to their high chemical homogeneity, low processing temperatures, possibility of controlling of the size and morphology of particles. In order to prepare sol-gel glasses we used the method of hydrolyzing TEOS and adding different dyes into the solution. The optical properties of different organic and inorganic dyes entrapped into the sol-gel matrices are investigated. These materials will be connected with optical fibers and will serve as optodes for pH and temperatures measurements.

The utility of autofluorescence imaging for the early detection of lung cancer has been previously demonstrated. The aim of this work is to extend the use of real time autofluorescence imaging to the early detection of cancer of the esophagus, stomach, and colon. A prototype fluorescence imaging system was developed which produces real time video images of tissue autofluorescence. The system consist of a filtered blue light source, two intensified CCD cameras, a fiber optic endoscope, and a computer based control center. The system produces a real time pseudo color display based on images acquired from two fluorescence bands. These bands were selected based on in vivo fluorescence spectroscopic studies. The generated pseudo image clearly delineates the abnormal tissue areas for biopsy. Early cancer sties missed under conventional white light examination became visible under fluorescence imaging. A further development allows the fluorescence imaging system to be used in an alternate fashion. The system captures a fluorescence image in the green and a reflectance image in the red-near IR. Different spectral information was exploited in the two imaging modes.