Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, sugg... more Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, suggests that a perilymphatic fistula (PLF) is present. PLF describes an abnormal communication between the middle and inner ear, and can result in deafness, vertigo, and imbalance. In the setting of a penetrating injury to the temporal bone or inner ear, pneumolabyrinth should trigger prompt otolaryngology consultation and urgent surgical exploration. We describe a case in which a 49-yearold male presented with a traumatic PLF secondary to penetrating ear injury. Imaging demonstrated extensive pneumolabyrinth. Despite delay in diagnosis, expeditious surgical intervention resulted in successful preservation of inner ear function. [Clin Pract Cases Emerg Med.2019;3(2):115-118.]
Determine the ability of three staging systems to stratify the risk of nodal metastases in cases ... more Determine the ability of three staging systems to stratify the risk of nodal metastases in cases of cutaneous squamous cell carcinoma (cSCC). Examine differential staging of tumors across the three systems and the resulting implications for clinical decision making.
Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, sugg... more Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, suggests that a perilymphatic fistula (PLF) is present. PLF describes an abnormal communication between the middle and inner ear, and can result in deafness, vertigo, and imbalance. In the setting of a penetrating injury to the temporal bone or inner ear, pneumolabyrinth should trigger prompt otolaryngology consultation and urgent surgical exploration. We describe a case in which a 49-yearold male presented with a traumatic PLF secondary to penetrating ear injury. Imaging demonstrated extensive pneumolabyrinth. Despite delay in diagnosis, expeditious surgical intervention resulted in successful preservation of inner ear function. [Clin Pract Cases Emerg Med.2019;3(2):115-118.]
SLAS TECHNOLOGY: Translating Life Sciences Innovation
Cerebrospinal fluid (CSF) leaks can occur when there is communication between the intracranial ca... more Cerebrospinal fluid (CSF) leaks can occur when there is communication between the intracranial cavities and the external environment. They are a common and serious complication of numerous procedures in otolaryngology, and if not treated, persistent leaks can increase a patient’s risk of developing life-threatening complications such as meningitis. As it is not uncommon for patients to exhibit increased secretions postoperatively, distinguishing normal secretions from those containing CSF can be difficult. Currently, there are no proven, available tests that allow a medical provider concerned about a CSF leak to inexpensively, rapidly, and noninvasively rule out the presence of a leak. The gold standard laboratory-based test requires that a sample be sent to a tertiary site for analysis, where days to weeks may pass before results return. To address this, our group recently developed a semiquantitative, barcode-style lateral-flow immunoassay (LFA) for the quantification of the beta-...
Objective A cerebrospinal fluid leak is one of the most serious complications in otolaryngology. ... more Objective A cerebrospinal fluid leak is one of the most serious complications in otolaryngology. It may occur as a result of injury to the skull base, typically traumatic or iatrogenic. While the presence of a leak is often discerned in the emergent setting, distinguishing normal secretions from those containing cerebrospinal fluid can be difficult during postoperative visits in the clinic. As most current laboratory-based assays are labor intensive and require several days to result, we aim to develop a more user-friendly and rapid point-of-care cerebrospinal fluid detection device. Study Design Our laboratory developed a barcode-style lateral-flow immunoassay utilizing antibodies for beta-trace protein, a protein abundant in and specific for cerebrospinal fluid, with a concentration of 1.3 mg/L delineating a positive result. Setting Tertiary medical center. Subjects and Methods Tests with known concentrations of resuspended beta-trace protein and the contents of discarded lumbar d...
Identify the effect of patient characteristics, disease traits, and treatment modality on patient... more Identify the effect of patient characteristics, disease traits, and treatment modality on patient outcomes in the rare disease process of intraosseous mucoepidermoid carcinoma. Retrospective review of institutional case records and literature. This study includes one case report, a literature review of the MEDLINE database from 1950 through June 2017 using keywords "intraosseous" and "mucoepidermoid," and a query of the University of California, Los Angeles, Department of Pathology database for all documented cases of intraosseous mucoepidermoid carcinoma of the head and neck. Indicators of poorer prognosis were male gender (P = 0.0071) and higher histological grade (P = 0.0095). Lesion site, size, association with odontogenic cyst, and treatment type did not have a statistically significant correlation with patient outcomes. There also was no statistically significant correlation observed between treatment modality and recurrent or progressive disease when stratified by histological grade of the cancer. This study identified male gender and high histological tumor grade as poor prognostic indicators; however, it did not reveal a statistically significant relationship between treatment modality and patient outcomes. Data regarding patient outcomes following treatment was limited due to loss to follow-up, suggesting that further investigation is required. Based on this review, decisions regarding treatment should be clinically guided and individually tailored to the patient's baseline health, disease severity, and the patient's treatment goals. A multi-disciplinary conference, as was utilized in the presented case report, may be the best approach to treatment planning for these patients at this time. 4. Laryngoscope, 2017.
International Journal of Pediatric Otorhinolaryngology Extra, 2016
Abstract Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy of childhood... more Abstract Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy of childhood. Early diagnosis is essential in determining prognosis and guiding treatment. This can be difficult as it has a spectrum of histological appearances. Here we present the case of a 14-year-old with a high-grade, sebaceous variant. Though initially diagnosed as benign sebaceous adenoma, fine needle aspiration performed for suspected recurrence revealed MEC. After parotidectomy confirmed this finding, a substantial defect remained and reconstruction using an anterolateral thigh free flap was performed. Furthermore, radiation was implemented and thought to have played a role in the successful outcome of this patient.
Objective Cisplatin is a platinum-based chemotherapeutic drug that secondarily induces toxicity i... more Objective Cisplatin is a platinum-based chemotherapeutic drug that secondarily induces toxicity in inner ear sensory epithelia, contributing to auditory and vestibular dysfunction. We describe the creation of a drug reservoir device (DRD) to combat this ototoxicity for the duration of chemotherapy. As ototoxic side effects of chemotherapy may limit an oncologist’s ability to prescribe first-line agents such as cisplatin, mitigating such devastating effects through prolonged topical therapy would be tremendously valuable. Study Design We investigated (1) the ability of an electrospun polylactic acid DRD to provide prolonged delivery of the posited otoprotectant metformin and (2) the development of an in vitro model utilizing Sh-Sy5y human neuroblastoma cells to assess the efficacy of metformin in reducing cisplatin-induced toxicity. Setting Neurophysiology laboratory. Methods Basic science experiments were performed to assess DRD properties and metformin’s effects on cisplatin toxici...
Advances in microfabrication techniques have enabled the production of inexpensive and reproducib... more Advances in microfabrication techniques have enabled the production of inexpensive and reproducible microfluidic systems for conducting biological and biochemical experiments at the micro- and nanoscales (1,2). In addition, microfluidics have also been specifically used to quantitatively analyze hematologic and microvascular processes, because of their ability to easily control the dynamic fluidic environment and biological conditions(3-6). As such, researchers have more recently used microfluidic systems to study blood cell deformability, blood cell aggregation, microvascular blood flow, and blood cell-endothelial cell interactions(6-13).However, these microfluidic systems either did not include cultured endothelial cells or were larger than the sizescale relevant to microvascular pathologic processes. A microfluidic platform with cultured endothelial cells that accurately recapitulates the cellular, physical, and hemodynamic environment of the microcirculation is needed to further our understanding of the underlying biophysical pathophysiology of hematologic diseases that involve the microvasculature. Here, we report a method to create an "endothelialized" in vitro model of the microvasculature, using a simple, single mask microfabrication process in conjunction with standard endothelial cell culture techniques, to study pathologic biophysical microvascular interactions that occur in hematologic disease. This "microvasculature-on-a-chip" provides the researcher with a robust assay that tightly controls biological as well as biophysical conditions and is operated using a standard syringe pump and brightfield/fluorescence microscopy. Parameters such as microcirculatory hemodynamic conditions, endothelial cell type, blood cell type(s) and concentration(s), drug/inhibitory concentration etc., can all be easily controlled. As such, our microsystem provides a method to quantitatively investigate disease processes in which microvascular flow is impaired due to alterations in cell adhesion, aggregation, and deformability, a capability unavailable with existing assays.
To activate clot formation and maintain hemostasis, platelets adhere and spread onto sites of vas... more To activate clot formation and maintain hemostasis, platelets adhere and spread onto sites of vascular injury. Although this process is well-characterized biochemically, how the physical and spatial cues in the microenvironment affect platelet adhesion and spreading remain unclear. In this study, we applied deep UV photolithography and protein micro/nanostamping to quantitatively investigate and characterize the spatial guidance of platelet spreading at the single cell level and with nanoscale resolution. Platelets adhered to and spread only onto micropatterned collagen or fibrinogen surfaces and followed the microenvironmental geometry with high fidelity and with single micron precision. Using micropatterned lines of different widths, we determined that platelets are able to conform to micropatterned stripes as thin as 0.6 mm and adopt a maximum aspect ratio of 19 on those protein patterns. Interestingly, platelets were also able to span and spread over non-patterned regions of up to 5 mm, a length consistent with that of maximally extended filopodia. This process appears to be mediated by platelet filopodia that are sensitive to spatial cues. Finally, we observed that microenvironmental geometry directly affects platelet biology, such as the spatial organization and distribution of the platelet actin cytoskeleton. Our data demonstrate that platelet spreading is a finely-tuned and spatially-guided process in which spatial cues directly influence the biological aspects of how clot formation is regulated.
Platelets interact with fibrin polymers to form blood clots at sites of vascular injury 1-3 . Bul... more Platelets interact with fibrin polymers to form blood clots at sites of vascular injury 1-3 . Bulk studies have shown clots to be active materials, with platelet contraction driving the retraction and stiffening of clots 4 . However, neither the dynamics of single-platelet contraction nor the strength and elasticity of individual platelets, both of which are important for understanding clot material properties, have been directly measured. Here we use atomic force microscopy to measure the mechanics and dynamics of single platelets. We find that platelets contract nearly instantaneously when activated by contact with fibrinogen and complete contraction within 15 min. Individual platelets can generate an average maximum contractile force of 29 nN and form adhesions stronger than 70 nN. Our measurements show that when exposed to stiffer microenvironments, platelets generated higher stall forces, which indicates that platelets may be able to contract heterogeneous clots more uniformly. The high elasticity of individual platelets, measured to be 10 kPa after contraction, combined with their high contractile forces, indicates that clots may be stiffened through direct reinforcement by platelets as well as by strain stiffening of fibrin under tension due to platelet contraction. These results show how the mechanosensitivity and mechanics of single cells can be used to dynamically alter the material properties of physiologic systems.
In hematologic diseases, such as sickle cell disease (SCD) and hemolytic uremic syndrome (HUS), p... more In hematologic diseases, such as sickle cell disease (SCD) and hemolytic uremic syndrome (HUS), pathological biophysical interactions among blood cells, endothelial cells, and soluble factors lead to microvascular occlusion and thrombosis. Here, we report an in vitro "endothelialized" microfluidic microvasculature model that recapitulates and integrates this ensemble of pathophysiological processes. Under controlled flow conditions, the model enabled quantitative investigation of how biophysical alterations in hematologic disease collectively lead to microvascular occlusion and thrombosis. Using blood samples from patients with SCD, we investigated how the drug hydroxyurea quantitatively affects microvascular obstruction in SCD, an unresolved issue pivotal to understanding its clinical efficacy in such patients. In addition, we demonstrated that our microsystem can function as an in vitro model of HUS and showed that shear stress influences microvascular thrombosis/obstruction and the efficacy of the drug eptifibatide, which decreases platelet aggregation, in the context of HUS. These experiments establish the versatility and clinical relevance of our microvasculature-on-a-chip model as a biophysical assay of hematologic pathophysiology as well as a drug discovery platform.
Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, sugg... more Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, suggests that a perilymphatic fistula (PLF) is present. PLF describes an abnormal communication between the middle and inner ear, and can result in deafness, vertigo, and imbalance. In the setting of a penetrating injury to the temporal bone or inner ear, pneumolabyrinth should trigger prompt otolaryngology consultation and urgent surgical exploration. We describe a case in which a 49-yearold male presented with a traumatic PLF secondary to penetrating ear injury. Imaging demonstrated extensive pneumolabyrinth. Despite delay in diagnosis, expeditious surgical intervention resulted in successful preservation of inner ear function. [Clin Pract Cases Emerg Med.2019;3(2):115-118.]
Determine the ability of three staging systems to stratify the risk of nodal metastases in cases ... more Determine the ability of three staging systems to stratify the risk of nodal metastases in cases of cutaneous squamous cell carcinoma (cSCC). Examine differential staging of tumors across the three systems and the resulting implications for clinical decision making.
Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, sugg... more Pneumolabyrinth, defined as air within the labyrinth on high-resolution computed tomography, suggests that a perilymphatic fistula (PLF) is present. PLF describes an abnormal communication between the middle and inner ear, and can result in deafness, vertigo, and imbalance. In the setting of a penetrating injury to the temporal bone or inner ear, pneumolabyrinth should trigger prompt otolaryngology consultation and urgent surgical exploration. We describe a case in which a 49-yearold male presented with a traumatic PLF secondary to penetrating ear injury. Imaging demonstrated extensive pneumolabyrinth. Despite delay in diagnosis, expeditious surgical intervention resulted in successful preservation of inner ear function. [Clin Pract Cases Emerg Med.2019;3(2):115-118.]
SLAS TECHNOLOGY: Translating Life Sciences Innovation
Cerebrospinal fluid (CSF) leaks can occur when there is communication between the intracranial ca... more Cerebrospinal fluid (CSF) leaks can occur when there is communication between the intracranial cavities and the external environment. They are a common and serious complication of numerous procedures in otolaryngology, and if not treated, persistent leaks can increase a patient’s risk of developing life-threatening complications such as meningitis. As it is not uncommon for patients to exhibit increased secretions postoperatively, distinguishing normal secretions from those containing CSF can be difficult. Currently, there are no proven, available tests that allow a medical provider concerned about a CSF leak to inexpensively, rapidly, and noninvasively rule out the presence of a leak. The gold standard laboratory-based test requires that a sample be sent to a tertiary site for analysis, where days to weeks may pass before results return. To address this, our group recently developed a semiquantitative, barcode-style lateral-flow immunoassay (LFA) for the quantification of the beta-...
Objective A cerebrospinal fluid leak is one of the most serious complications in otolaryngology. ... more Objective A cerebrospinal fluid leak is one of the most serious complications in otolaryngology. It may occur as a result of injury to the skull base, typically traumatic or iatrogenic. While the presence of a leak is often discerned in the emergent setting, distinguishing normal secretions from those containing cerebrospinal fluid can be difficult during postoperative visits in the clinic. As most current laboratory-based assays are labor intensive and require several days to result, we aim to develop a more user-friendly and rapid point-of-care cerebrospinal fluid detection device. Study Design Our laboratory developed a barcode-style lateral-flow immunoassay utilizing antibodies for beta-trace protein, a protein abundant in and specific for cerebrospinal fluid, with a concentration of 1.3 mg/L delineating a positive result. Setting Tertiary medical center. Subjects and Methods Tests with known concentrations of resuspended beta-trace protein and the contents of discarded lumbar d...
Identify the effect of patient characteristics, disease traits, and treatment modality on patient... more Identify the effect of patient characteristics, disease traits, and treatment modality on patient outcomes in the rare disease process of intraosseous mucoepidermoid carcinoma. Retrospective review of institutional case records and literature. This study includes one case report, a literature review of the MEDLINE database from 1950 through June 2017 using keywords "intraosseous" and "mucoepidermoid," and a query of the University of California, Los Angeles, Department of Pathology database for all documented cases of intraosseous mucoepidermoid carcinoma of the head and neck. Indicators of poorer prognosis were male gender (P = 0.0071) and higher histological grade (P = 0.0095). Lesion site, size, association with odontogenic cyst, and treatment type did not have a statistically significant correlation with patient outcomes. There also was no statistically significant correlation observed between treatment modality and recurrent or progressive disease when stratified by histological grade of the cancer. This study identified male gender and high histological tumor grade as poor prognostic indicators; however, it did not reveal a statistically significant relationship between treatment modality and patient outcomes. Data regarding patient outcomes following treatment was limited due to loss to follow-up, suggesting that further investigation is required. Based on this review, decisions regarding treatment should be clinically guided and individually tailored to the patient's baseline health, disease severity, and the patient's treatment goals. A multi-disciplinary conference, as was utilized in the presented case report, may be the best approach to treatment planning for these patients at this time. 4. Laryngoscope, 2017.
International Journal of Pediatric Otorhinolaryngology Extra, 2016
Abstract Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy of childhood... more Abstract Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy of childhood. Early diagnosis is essential in determining prognosis and guiding treatment. This can be difficult as it has a spectrum of histological appearances. Here we present the case of a 14-year-old with a high-grade, sebaceous variant. Though initially diagnosed as benign sebaceous adenoma, fine needle aspiration performed for suspected recurrence revealed MEC. After parotidectomy confirmed this finding, a substantial defect remained and reconstruction using an anterolateral thigh free flap was performed. Furthermore, radiation was implemented and thought to have played a role in the successful outcome of this patient.
Objective Cisplatin is a platinum-based chemotherapeutic drug that secondarily induces toxicity i... more Objective Cisplatin is a platinum-based chemotherapeutic drug that secondarily induces toxicity in inner ear sensory epithelia, contributing to auditory and vestibular dysfunction. We describe the creation of a drug reservoir device (DRD) to combat this ototoxicity for the duration of chemotherapy. As ototoxic side effects of chemotherapy may limit an oncologist’s ability to prescribe first-line agents such as cisplatin, mitigating such devastating effects through prolonged topical therapy would be tremendously valuable. Study Design We investigated (1) the ability of an electrospun polylactic acid DRD to provide prolonged delivery of the posited otoprotectant metformin and (2) the development of an in vitro model utilizing Sh-Sy5y human neuroblastoma cells to assess the efficacy of metformin in reducing cisplatin-induced toxicity. Setting Neurophysiology laboratory. Methods Basic science experiments were performed to assess DRD properties and metformin’s effects on cisplatin toxici...
Advances in microfabrication techniques have enabled the production of inexpensive and reproducib... more Advances in microfabrication techniques have enabled the production of inexpensive and reproducible microfluidic systems for conducting biological and biochemical experiments at the micro- and nanoscales (1,2). In addition, microfluidics have also been specifically used to quantitatively analyze hematologic and microvascular processes, because of their ability to easily control the dynamic fluidic environment and biological conditions(3-6). As such, researchers have more recently used microfluidic systems to study blood cell deformability, blood cell aggregation, microvascular blood flow, and blood cell-endothelial cell interactions(6-13).However, these microfluidic systems either did not include cultured endothelial cells or were larger than the sizescale relevant to microvascular pathologic processes. A microfluidic platform with cultured endothelial cells that accurately recapitulates the cellular, physical, and hemodynamic environment of the microcirculation is needed to further our understanding of the underlying biophysical pathophysiology of hematologic diseases that involve the microvasculature. Here, we report a method to create an "endothelialized" in vitro model of the microvasculature, using a simple, single mask microfabrication process in conjunction with standard endothelial cell culture techniques, to study pathologic biophysical microvascular interactions that occur in hematologic disease. This "microvasculature-on-a-chip" provides the researcher with a robust assay that tightly controls biological as well as biophysical conditions and is operated using a standard syringe pump and brightfield/fluorescence microscopy. Parameters such as microcirculatory hemodynamic conditions, endothelial cell type, blood cell type(s) and concentration(s), drug/inhibitory concentration etc., can all be easily controlled. As such, our microsystem provides a method to quantitatively investigate disease processes in which microvascular flow is impaired due to alterations in cell adhesion, aggregation, and deformability, a capability unavailable with existing assays.
To activate clot formation and maintain hemostasis, platelets adhere and spread onto sites of vas... more To activate clot formation and maintain hemostasis, platelets adhere and spread onto sites of vascular injury. Although this process is well-characterized biochemically, how the physical and spatial cues in the microenvironment affect platelet adhesion and spreading remain unclear. In this study, we applied deep UV photolithography and protein micro/nanostamping to quantitatively investigate and characterize the spatial guidance of platelet spreading at the single cell level and with nanoscale resolution. Platelets adhered to and spread only onto micropatterned collagen or fibrinogen surfaces and followed the microenvironmental geometry with high fidelity and with single micron precision. Using micropatterned lines of different widths, we determined that platelets are able to conform to micropatterned stripes as thin as 0.6 mm and adopt a maximum aspect ratio of 19 on those protein patterns. Interestingly, platelets were also able to span and spread over non-patterned regions of up to 5 mm, a length consistent with that of maximally extended filopodia. This process appears to be mediated by platelet filopodia that are sensitive to spatial cues. Finally, we observed that microenvironmental geometry directly affects platelet biology, such as the spatial organization and distribution of the platelet actin cytoskeleton. Our data demonstrate that platelet spreading is a finely-tuned and spatially-guided process in which spatial cues directly influence the biological aspects of how clot formation is regulated.
Platelets interact with fibrin polymers to form blood clots at sites of vascular injury 1-3 . Bul... more Platelets interact with fibrin polymers to form blood clots at sites of vascular injury 1-3 . Bulk studies have shown clots to be active materials, with platelet contraction driving the retraction and stiffening of clots 4 . However, neither the dynamics of single-platelet contraction nor the strength and elasticity of individual platelets, both of which are important for understanding clot material properties, have been directly measured. Here we use atomic force microscopy to measure the mechanics and dynamics of single platelets. We find that platelets contract nearly instantaneously when activated by contact with fibrinogen and complete contraction within 15 min. Individual platelets can generate an average maximum contractile force of 29 nN and form adhesions stronger than 70 nN. Our measurements show that when exposed to stiffer microenvironments, platelets generated higher stall forces, which indicates that platelets may be able to contract heterogeneous clots more uniformly. The high elasticity of individual platelets, measured to be 10 kPa after contraction, combined with their high contractile forces, indicates that clots may be stiffened through direct reinforcement by platelets as well as by strain stiffening of fibrin under tension due to platelet contraction. These results show how the mechanosensitivity and mechanics of single cells can be used to dynamically alter the material properties of physiologic systems.
In hematologic diseases, such as sickle cell disease (SCD) and hemolytic uremic syndrome (HUS), p... more In hematologic diseases, such as sickle cell disease (SCD) and hemolytic uremic syndrome (HUS), pathological biophysical interactions among blood cells, endothelial cells, and soluble factors lead to microvascular occlusion and thrombosis. Here, we report an in vitro "endothelialized" microfluidic microvasculature model that recapitulates and integrates this ensemble of pathophysiological processes. Under controlled flow conditions, the model enabled quantitative investigation of how biophysical alterations in hematologic disease collectively lead to microvascular occlusion and thrombosis. Using blood samples from patients with SCD, we investigated how the drug hydroxyurea quantitatively affects microvascular obstruction in SCD, an unresolved issue pivotal to understanding its clinical efficacy in such patients. In addition, we demonstrated that our microsystem can function as an in vitro model of HUS and showed that shear stress influences microvascular thrombosis/obstruction and the efficacy of the drug eptifibatide, which decreases platelet aggregation, in the context of HUS. These experiments establish the versatility and clinical relevance of our microvasculature-on-a-chip model as a biophysical assay of hematologic pathophysiology as well as a drug discovery platform.
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Papers by Ashley Kita