The plasminogen activator (PA) system has been shown to be intimately involved in wound healing. However, the role of this system in the initiation and resolution of inflammation during healing process remained to be determined. The aims of this thesis were to investigate the molecular mechanism underlying the interaction between the PA system and the inflammatory system during wound healing and to explore the therapeutic potential of plasminogen in various wound-healing models. The role of plasminogen in the inflammatory phase of the healing process of acute and diabetic wounds was studied first. Our data showed that administration of additional plasminogen to wild-type mice accelerates the healing of acute wounds. After injury, both endogenous and exogenous plasminogen are bound to inflammatory cells and are transported to the wound site, which leads to activation of inflammatory cells. In diabetic db/db mice, wound-specific accumulation of plasminogen does not take place and the inflammatory response is impaired. However, when additional plasminogen is injected, plasminogen accumulates in the wound, the inflammatory response is enhanced, the signal transduction cascade is activated and the healing rate is significantly increased. These results indicate that administration of plasminogen may be a novel therapeutic strategy to treat different types of wounds, especially chronic wounds in diabetes. The role of plasminogen at the later stage of wound healing was also studied in plasminogen-deficient mice. Our data showed that even if re-epithelialization is achieved in these mice, a prolonged inflammatory phase with abundant neutrophil accumulation and persistent fibrin deposition is observed at the wound site. These results indicate that plasminogen is also essential for the later phases of wound healing by clearing fibrin and resolving inflammation. The functional role of two physiological PAs during wound healing was further studied in a tympanic membrane (TM) wound-healing model. Our data showed that the healing process was clearly delayed in urokinase-type PA (uPA)-deficient mice but not in tissue-type PA (tPA)-deficient mice. Less pronounced keratinocyte migration, abundant neutrophil accumulation and persistent fibrin deposition were observed in uPA-deficient mice. These results indicate that uPA plays a central role in the generation of plasmin during the healing of TM perforations. Finally the therapeutic potential of plasminogen in the TM wound-healing model was studied. Our data showed that local injection of plasminogen restores the ability to heal TM perforations in plasminogen-deficient mice in a dose-dependent manner. Plasminogen supplementation also potentiates healing of acute TM perforations in wild-type mice, independent of the administration method used. A single local injection of plasminogen in plasminogen-deficient mice can initiate healing of chronic TM perforations resulting in a closed TM with a continuous but rather thick outer keratinocyte layer. Three plasminogen injections lead to a completely healed TM with a thin keratinizing squamous epithelium covering a connective tissue layer that can start to reorganize and further mature to its normal appearance. In conclusion, our results suggest that plasminogen is a promising drug candidate for the treatment of chronic TM perforations in humans.  Taken together, our data indicate that plasminogen is a novel inflammatory regulator that promotes wound healing.

No description available.

Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 5 uppsatser.

In recent years, tympanometry has been used to provide objective and definitive information regarding the status of middle ear conditions and functions. The present standard for tympanometric normalcy is based upon between-subject measures. This standard, however, does not allow precise differentiation between normal and pathological tympanometry curves. A within-subject comparison of right and left ear tympanometry curves of normal-hearing subjects could provide a narrow standard of tympanometric normalcy which would be more useful in differentiating between pathologic and non-pathologic middle ear function. The within-subject relationship between tympanometry curves for right and left ears was investigated by comparing the individual right and left ear tympanometry curves at 220 and 660 Hz of 30 normal-hearing young adults. This was done to determine if a difference exists between within-subject right and left ear tympanometry curves. Three characteristics, curve peak amplitude, curve width, and pressure at curve peak, were measured and compared for each tympanometry curve. All tympanometry was conducted with a Grason-Stadler Otoadmittance Meter (Model 1720) utilizing a combined mode of conductance and susceptance. All tympanometry curves were graphically recorded on a Hewlitt-Packard X-Y plotter (Model 7035B). Statistical analysis and graphic illustration showed that for practical purposes no significant clinical difference exists between within-subject right and left ear tympanometry curves and that measurement variability is predominantly due to between-subject differences. The ranges of between-ear differences were much reduced in comparison to the computed ranges for between-subject measures. These findings would suggest that a definition of tympanometric normalcy should be based not only upon between-subject measures, but also upon between-ear comparisons

No description available.

The hyoid apparatus in laryngeally echolocating bats forms a mechanical connection between the larynx and auditory bullae and has been hypothesized to transfer the outgoing echolocation call to the middle ear during echolocation call emission. We used µCT data to build models of the hyoid apparatus and middle ear from six species of bats and used finite element modeling (FEM) to measure the vibroacoustic response of the tympanic membrane due to hyoid-borne sound generated during echolocation. We found that hyoid-borne sound in all six species stimulated the eardrum within a range likely heard by bats. Although there were minor differences at frequencies above 60kHz, there were no obvious morphological explanations to account for it. This suggests that variation in the morphology of the hyoid apparatus in laryngeally echolocating bats is likely driven by other functions associated with the hyoid.

"Hearing loss affects approximately 1 in 10 people in the world and this percentage is increasing every year. Some of the most common causes of hearing loss are disorders of the middle-ear. Early detection and diagnosis of hearing loss as well as research to understand the hearing processes depend on medical and research tools for quantification of hearing capabilities and the function of the middle-ear in the complex acousto-mechanical transformation of environmental sounds into vibrations of the middle-ear, particular of the human tympanic membrane (TM or eardrum). Current ear exams assess the state of a patient’s hearing capabilities mainly based on qualitative evaluation of the healthiness of the TM. Existing quantitative clinical methods for description of the motion of the TM are limited to either average acoustic estimates (admittance or reflectance) or single-point displacement measurements. Such methods could leave examiners and researchers blind to the complex spatio-temporal response of the nanometer scale displacements of the entire TM. Current state-of-the-art medical research tools provide full-field nanometer displacement measurements of the surface of the human TM excited by steady state (tonal) stimuli. However, to fully understand the mechanics of hearing, and the complex acousto-mechanical characteristics of TM in particular, new tools are needed for full-field high-speed characterization of the nanometer scale displacements of the human TM subjected to impulse (wideband) acoustic excitation. This Dissertation reports the development of a new high-speed holographic system (HHS) for full-field nanometer transient (i.e., > 10 kHz) displacement measurement of the human middle-ear and the tympanic membrane, in particular. The HHS allows spatial (i.e., >500k data points) and temporal (i.e., > 40 kHz) resolutions that enable the study of the acoustical and mechanical characteristics of the middle-ear at a level of detail that have never been reached before. The realization of the HHS includes the development and implementation of novel phase sampling and acquisition approaches that allow the use of state-of-the-art high-resolution (i.e., >5 MP) and high-speed (> 80,000 fps) cameras through modular and expandable control architectures. The development of novel acquisition approaches allows the use of conventional speed (i.e., <20 fps) cameras to realize high-temporal resolutions (i.e., <15 us) at equivalent sampling rates of > 50,000 fps with minimum hardware cost and modifications. The design and implementation of novel spatio-temporal phase sampling methods utilize the high temporal resolution (i.e., < 5 us exposure) and frame rate (i.e., >80,000 fps) of high-speed cameras without imposing constraints on their spatial resolution (i.e., >20 um pixel size). Additionally, the research and in-vivo applications capabilities of the HHS are extended through the development and implementation of a holographic otoscope head (OH) and a mechatronic otoscope positioner (MOP). The large (i.e., > 1 GB with > 8x10^9 parameters) spatio-temporal data sets of the HHS measurements are automatically processed by custom parallel data mining and interpretation (PDMI) methods, which allow automatic quantification of medically relevant motion parameters (MRMPs), such as modal frequencies, time constants, and acoustic delays. Such capabilities could allow inferring local material properties across the surface of the TM. The HHS is a new medical tool that enables otologists to improve the quality of diagnosis and treatments as well as provides researchers with spatio-temporal information of the hearing process at a level of detail never reached before. "

The middle ear plays an integral role in the normal hearing process by transforming sound energy from the air inside the ear canal into vibrations of the inner-ear fluid, and a malfunction in any middle-ear component can lead to significant hearing loss. Despite decades of research on the Tympanic Membrane (TM or eardrum), the transformation of sound energy into ossicular mechanical vibrations is not yet well understood. Part of this is because the available clinical and research tools provide insufficient data to understand the complexities of this transformation. The data insufficiency arises due to methodological, technological, and physiological limitations such as required nanometer and microsecond spatio-temporal resolutions of the sound-induced TM motions. Although holographic methods provide nondestructive non-contact measuring capabilities that satisfy most of the constraints for TM measurements, the influence of large submillimeter scale physiological motions in live samples produced by heartbeat and breathing can result in near complete saturation of TM holograms. In this Dissertation, a new high-speed correlation interferometry holographic method is proposed that can compensate for the effects of physiological noise using an open-loop control configuration. Preliminary animal measurements with the proposed method demonstrate the necessary accuracy and precision to measure the motion of the entire TM produced by short- duration (≥1 kHz) transient stimuli. Such rapid measurements reduce the effect of the longer and slower environmental and physiologic noises, and enable clinical applications. In the second part of this Dissertation, a novel multiple wavelength high-speed holographic interferometric shape measurement method is incorporated into the high-speed displacement measurements. The method uses the imaging optics of the displacement measurement system to perform shape and orientation measurements. Displacement and shape measurements can be made in less than 200 msec and allow computation of true surface-normal displacements. The surface-normal measurements are independent of the direction of observation, which helps comparisons of measurements made after changes in TM orientation or location. The results enable accurate and precise shape and displacement measurements for use in applications such as modal and finite element analyses, additive manufacturing of prosthetic TM grafts, clinical diagnosis, hearing rehabilitation, as well as optimization of hearing devices. In addition, measured shape parameters such as curvature, depth of cone etc., can help us understand TM mechanics and contribute to quantitative diagnostic assessments.

The conventional methods for diagnosing pathological conditions of the tympanic membrane (TM) and other abnormalities require measuring its motion while responding to acoustic excitation. Current methodologies for characterizing the motion of the TM are usually limited to either average acoustic estimates (admittance or reflectance) or single-point mobility measurements, neither of which is sufficient to characterize the detailed mechanical response of the TM to sound. Furthermore, while acoustic and single-point measurements are useful for the diagnosis of some middle ear disorders, they are not useful in others. Measurements of the motion of the entire TM surface can provide more information than these other techniques and may be superior for the diagnosis of pathology. In this Thesis, the development of an optoelectronic holographic otoscope (OEHO) system for characterization of nanometer scale motions in TMs is presented. The OEHO system can provide full-field-of-view information of the sound-induced displacements of the entire surface of the TM at video rates, allowing rapid quantitative analysis of the mechanical response of normal or pathological TMs. Preliminary measurements of TM motion in cadaveric animals helped constrain the optical design parameters for the OEHO, including the following: image contrast, resolution, depth of field (DOF), laser power, working distance between the interferometer and TM, magnification, and field of view (FOV). Specialized imaging software was used in selecting and synthesizing the various components. Several prototypes were constructed and characterized. The present configuration has a resolution of 57.0 line pairs/mm, DOF of 5 mm, FOV of 10 ´ 10 mm2, and a 473 nm laser with illumination power of 15 mW. The OEHO system includes a computer controlled digital camera, a fiber optic subsystem for transmission and modulation of laser light, and an optomechanical system for illumination and observation of the TM. The OEHO system is capable of operating in two modes. A 'time-averaged' mode, processed at video rates, was used to characterize the frequency dependence of TM displacements as tone frequency was swept from 500 Hz to 25 kHz. A 'double-exposure' mode was used at selected frequencies to measure, in full-field-of-view, displacements of the TM surface with nanometer resolution. The OEHO system has been designed, fabricated, and evaluated, and is currently being evaluated in a medical-research environment to address basic science questions regarding TM function. Representative time-averaged holographic and stroboscopic interferometry results in post-mortem and live samples are herein shown, and the potential utilization discussed.

Current methodologies for characterization of tympanic membranes (TMs) have some limitations. They: are qualitative rather than quantitative, consist of single point mobility measurements, or only include one-dimensional deformation measurements. Furthermore, none of the current clinical tools for diagnosis of hearing losses have the capability to measure the shape of TM, which is very useful for anatomical or pathological investigations. The multi-wavelength lensless digital holography system (MLDHS) reported in this work consists of laser delivery (LD), optical head (OH), and computing platform (CP) subsystems, with capabilities of real-time, non-contact, full-field of view measurements. One version of the LD houses two tunable near-infrared external-cavity diode lasers with central wavelengths of 780.24nm and 779.74nm respectively, an acousto-optic modulator, and a laser-to-fiber mechanism. The output of the LD is delivered to an ultra-fast MEMS-based fiber optic switch and the light beam is directed to the OH, which is arranged to perform imaging and measurements by phase-shifting holography. The second LD version subsystem contains one tunable near-infrared diode laser in the range from 770nm to 789nm, an anamorphic prism pair, an acousto-optic modulator, a half-wave plate, and a fiber coupler assembly. The output of the LD is delivered to the OH directly. The OH is designed by 3D optical ray tracing simulations in which components are rotated at specific angles to overcome reflection issues. A high-resolution digital camera with pixel size of 6.7μm by 6.7μm in the OH is used for image recording at high-rates while the CP acquires and processes images in either time-averaged or double-exposure modes. The choice of working version depends on the requirements of the measurement and the sample under test. MLDHS can obtain shape and one-dimensional deformations along one optical axis (z-axis). In order to recover 3D deformations, assumptions based on elasticity theory are prerequisites for the calculations: (a) the TM is analyzed as a thin shell; (b) shape before and after deformation is considered nearly the same since acoustic pressure typically introduces nanometer scale deformations; and (c) normal vectors remain perpendicular to the deformed mid-plane of the TM. Another part of this Thesis is the design and prototyping of the MLDHS, which translates this holographic platform into a simple and compact holographic instrument for measurements of the visible tympanic-membrane motions in live patients. Therefore, the OH subsystem needs to be light and portable, as it can be mounted on a robotic arm be near the ear canal, while the LD subsystem needs to be stable and safely protected. Preliminary results of acoustically induced 3D deformations and shape measurements by a single instrument that demonstrate the capabilities of the devices developed in this Thesis are presented.