Nikolaos Chronis - US grants

DESCRIPTION (Provided by the applicant) Abstract: HIV/AIDS is one of the most destructive pandemics in human history, responsible for more than 25 million deaths. More than 30 million people live with limited or no access to therapeutic treatments, mainly due to the high cost of highly active antiretroviral therapies (HAART) and current diagnostic tests as well as due to the lack of basic infrastructure (e.g. lack of electricity, no trained personnel) that can support these tests. The need for innovative, inexpensive diagnostic instrumentation technology that can be used in resourcelimited settings is immediate. While programs that offer free HAART are being implemented in resource-limited settings, no diagnostic tests are available for evaluating the efficacy of HAART provided for the reasons mentioned above. Efficient management of HAART requires monitoring the course of HIV infection over time. The World Health Organization recommends the CD4+ T-cell count test for monitoring the clinical status of HIV individuals in resource-limited settings. We propose to develop a portable, inexpensive, MEMS (MicroElectroMechanical Systems)-based, imaging system for counting the absolute number of CD4 cells from 1 [unreadable]l of whole blood. We use the term 'imaging system'to denote the different approach we follow for counting CD4 cells: rather the reading one by one singles cells (as it is done with flow cytometry), our system can image simultaneously thousands of individual cells, pre-assembled on the surface of a biochip. Although the proposed imaging system can replace current expensive cell counting instrumentation, our goal is to develop a system that can reach the end-user wherever limited infrastructure is present and no access to a hospital or clinic is possible. Such technology will not only enable to monitor the efficacy of an individual's HAART in the developing world, but it will make more medicines available by identifying patients who need a treatment from patients who do not need it. Public Health Relevance: Diagnostic tests for HIV/AIDS management are not available in resource-limited settings. Taking advantages from recent advances in microfabrication technology, we propose to develop a portable, point-of-care, inexpensive biochip for monitoring the progress of HIV/AIDS infection in patients residing in resource-limited settings.

DESCRIPTION (provided by applicant): Intracranial pressure (ICP) monitoring is an essential diagnostic tool for the efficient treatment of patients with brain injuries (e.g. traumatic brain injuries (TBIs)) and cerebrospinal fluid outflow disorders (e.g. hydrocephalus). Clinical trials have shown that ICP monitoring decreases the mortality rate and minimizes secondary injuries. Various ICP monitoring systems have been successful so far in accurately monitoring ICP, but: (a) they have high probability of infection (up to 15%), (b) they do not allow long-term ICP monitoring and (c) they are not MRI (Magnetic Resonance Imaging) compatible. Taking advantage of recent developments in the MicroElectroMechanical Systems (MEMS) field, we propose an 'Intracranial Pressure Micro Stick'(IP

DESCRIPTION (provided by applicant): Aging, a degenerative process when viewed from the biological prospective, is often associated with a high probability of an age-related disease or disability, low physical and mental function capacity and low engagement with life. Revealing how the overall neuronal functionality and how specific neuronal properties alter with age is considered to be a major step towards understanding the molecular mechanisms of age-related diseases and disorders. The multivariate, environment-dependant character of aging, led to the adoption of animal models that can be easily genetically manipulated, have a short lifespan and can develop and age in a controllable lab environment. Over the last three decades, C. elegans, a tiny nematode with powerful genetics and a well-defined nervous system, has become a prominent model organism for studying the process of aging. We propose to combine calcium imaging with microfluidics to quantify the effect of aging to the functionality of major sensory neurons (ASH, AWC, AFD) of C. elegans in vivo. We hypothesize that the biophysical properties of the sensory neurons in C.elegans are altered with age. We also hypothesize that oxidative stress is one factor that results in the degradation in the neuronal performance and that anti-oxidative stress substances can minimize oxidative damage. By using calcium indicators, we will be able to probe the biophysical properties (neuronal sensitivity, time response and amplitude of depolarization) of these neurons when triggered with a certain stimulus. The microfluidics will provide the automation that is required for obtaining repeatable and accurate imaging data from a large number of worms. In order to validate our hypotheses, imaging data from various populations of worms (wild-type, mutants and antioxidants-treated worms) of different ages will be compared and statistically significant trends will be obtained. PUBLIC HEALTH RELEVANCE: Aging is associated with a high probability of age-related diseases (Parkinson's and Alzheimer's disease), low physical and mental functional capacity and low engagement with life. We propose to study the effect of aging on sensory neurons in the nematode C. elegans using in vivo calcium imaging and microfluidic technology. We believe that our studies will deepen our understanding of the aging process in more sophisticated nervous systems

DESCRIPTION (provided by applicant): IntraOcular Pressure (IOP) monitoring is an essential diagnostic tool for the efficient treatment of glaucoma and other ocular hypertension-related diseases. Clinical trials have shown that frequent IOP monitoring can decelerate the progress of glaucoma and minimize optical nerve damage Current IOP monitoring technologies (e.g. tonometry) are non-invasive and simple to execute, but they are not accurate and not suitable for life-long and frequent IOP monitoring: they require a visit to the hospital or to a clinic as the measurement is performed by trained personnel. We propose a 'Near Infrared Fluorescent-based Optomechanical' (NiFO) IOP sensing technology for accurate, home-based, IOP monitoring for patients with moderate or severe glaucoma. The NiFO technology is based on an electronic-free MicroElectroMechanical Systems (MEMS) implantable sensor (termed the 'NiFO sensor') that converts IOP changes into a dual-wavelength optical signal in the near infrared (NI) regime. The NiFO sensor is integrated into an intraocular lens or surgically attached on the iris and therefore permanently implanted into the patient's eye. An external, portable optical readout system (ORS) is used to excite the NiFO sensor, collect and analyze the emitted NI optical signal. The power-free NiFO sensor permits frequent and life-long IOP monitoring, allows the patient to perform the IOP measurement at home, requires no maintenance (e.g. battery replacement), it is accurate and it has a very small size (< 0.5 mm3) and footprint (~0.25 mm2). Our research plan consists of the following aims: 1) Microfabrication and in vitro testing of the NiFO pressure sensor. The NiFO sensor, consisting of a silicon/PDMS chip will be microfabricated using standard bulk and surface silicon micromachining processes. Its specifications (dynamic range, precision error, etc) will be established in vitro by immersing the NIFO sensor into a bath filled with aqueous humor. 2) Construction of the Optical Readout System (ORS). A portable optical readout system consisting of an optical head and an excitation/detection unit will be manufactured. The system will integrate all the optics needed to excite the NiFO sensor, collect analyze the emitted NI fluorescence signal. The proposed technology will help in efficiently managing and treating glaucoma and hypertension-related diseases and it will trigger the development of other implantable, power-free, miniaturized devices that can be used in a variety of pressure monitoring biomedical applications. PUBLIC HEALTH RELEVANCE: Intraocular pressure (IOP) monitoring is an important diagnostic tool for accessing the pathological condition of patients with chronic glaucoma. This work aims to develop a new class of point-of-care, implantable IOP monitoring sensors that will provide better management and efficient treatment for such patients.

Circadian rhythms are endogenous self-sustained oscillations with 24h periods that regulate diverse physiological processes. Disruption of circadian rhythms is the first sign in patients with sleep disorders and it is used as diagnostic tool for these patients. Saliva melatonin measured in dim light conditions (DLMO) is a validated biomarker of circadian function used routinely in the Psychiatry and Sleep clinics worldwide. Current protocols for measuring DLMO require that patients remain in a specialized clinic for 24hrs and spit saliva in a tube every 30-60 min. However, because patients need to remain awake for 24hrs melatonin measurements in a hospital clinic setting are relative inaccurate because of sleep deprivation during the test period. Furthermore, patient hospitalization dramatically increases the costs of testing melatonin and decrease patient compliance for accepting the test. The overall focus of this project is to design and validate a novel multi-reservoir collecting saliva device that will allow to measure accurately DLMO levels and phase in a home setting. Our specific aims are to design, fabricate and validate a Saliva Micro-Array Retainer (SµR) to achieve multi-point passive saliva collection. This will allow accurately measurement of DLMO without the need of hospitalization. Our research is significant because will facilitate the utilization of DLMO measurements for sleep disorders and psychiatric patients. An increasing number of diseases is also linked to circadian clock dysregulation including autoimmune diseases (diabetes type I, rheumatoid arthritis, etc.) as well as different types of cancer where measurement of DLMO can become a key biomarker. These devices can also be used in the future for measuring a variety of other validated saliva biomarkers that are subject to circadian variation. In fact, over 50% of known saliva proteins are subject to significant daily variations and are direct targets of the circadian clock. With modifications (adaptation of a colorimetric assay in each chamber), SµR has also a great potential to be adapted in the near future as a real time 24hrs monitoring device for all saliva biomarkers. This clinically oriented study is performed by an experienced multidisciplinary team including Drs. Petros Papagerakis (salivary function and circadian rhythms biologist), Chronis (mechanical engineering and MicroElectroMechanical Systems expert), Silvana Papagerakis (oral medicine specialist in clinical circadian research including patient recruitment in clinical trials), and Uswak (a senior oral health epidemiologist).