Elastic particle deformation in rectangular channel flow as a measure of particle stiffness.

In this study, we experimentally observed and characterized soft elastic particle deformation in confined flow in a microchannel with a rectangular cross-section. Hydrogel microparticles of pNIPAM were produced using two different concentrations of crosslinker. This resulted in particles with two different shear moduli of 13.3 ± 5.5 Pa and 32.5 ± 15.7 Pa and compressive moduli of 66 ± 10 Pa and 79 ± 15 Pa, respectively, as measured by capillary micromechanics. Under flow, the particle shapes transitioned from circular to egg, triangular, arrowhead, and ultimately parachute shaped with increasing shear rate. The shape changes were reversible, and deformed particles relaxed back to circular/spherical in the absence of flow. The thresholds for each shape transition were quantified using a non-dimensional radius of curvature at the tip, particle deformation, circularity, and the depth of the concave dimple at the trailing edge. Several of the observed shapes were distinct from those previously reported in the literature for vesicles and capsules; the elastic particles had a narrower leading tip and a lower circularity. Due to variations in the shear moduli between particles within a batch of particles, each flow rate corresponded to a small but finite range of capillary number (Ca) and resulted in a series of shapes. By arranging the images on a plot of Ca versus circularity, a direct correlation was developed between shape and Ca and thus between particle deformation and shear modulus. As the shape was very sensitive to differences in shear modulus, particle deformation in confined flow may allow for better differentiation of microparticle shear modulus than other methods.

Oral lichenoid lesions: distinguishing the benign from the deadly.

Oral lichen planus is a chronic inflammatory disease of unknown etiology or pathogenesis with varied disease severity that waxes and wanes over a long period of time. Although a common oral mucosal disease, accurate diagnosis is often challenging due to the overlapping clinical and histopathological features of oral lichen planus and other mucosal diseases. Other immune-mediated mucocutaneous diseases can exhibit lichenoid features including mucous membrane pemphigoid, chronic graft-versus-host disease, and discoid lupus erythematosus. Reactive changes to dental materials or to systemic medications can mimic oral lichen planus both clinically and histologically. In these situations the clinical presentation can be useful, as oral lichen planus presents as a multifocal process and is usually symmetrical and bilateral. Dysplasia of the oral cavity can exhibit a lichenoid histology, which may mask the potentially premalignant features. Proliferative verrucous leukoplakia, an unusual clinical disease, can often mimic oral lichen planus clinically, requiring careful correlation of the clinical and pathologic features.

Generation and characterization of monodisperse deformable alginate and pNIPAM microparticles with a wide range of shear moduli.

Monodisperse particles of varying size, shape, and deformability were produced using two microfluidic strategies. For both strategies, monodisperse emulsion droplets of a crosslinkable solution were generated via flow-focusing. Subsequently, droplets were crosslinked either on chip or in an external bath. On-chip gelation resulted in spherical particles; varying the degree of crosslinking varied the deformability systematically. The optimized flow-focusing device design separated the production of monodisperse aqueous alginate droplets and the on-chip introduction of crosslinking ions. Two features were then adapted to target softer particles: the dispersed phase design and the polymer choice. The alternative design used a sheathed dispersed phase, with the polymer solution surrounding an unreactive viscous core, which generated alginate particles with a softer core. Poly(N-isopropylacrylamide) (pNIPAM) allowed access to a broad range of moduli. The resulting spherical particles were characterized using capillary micromechanics to determine the shear (G) and compressive (K) moduli. Particles with G = 0.013 kPa to 26 kPa and K = 0.221 kPa to 34.9 kPa were obtained; the softest particles are an order of magnitude softer than those previously reported. The second approach, based on earlier work by Hu et al., produced axisymmetric, non-spherical particles with fore-aft asymmetry. Alginate drops were again formed in a flow-focusing device but were crosslinked off-chip in an external gelation bath. By changing the bath viscosity, crosslinker concentration, and outlet height, the falling droplets deformed differently during gelation, resulting in a variety of shapes, such as teardrop, mushroom, and bowl shapes.

Insulin-regulated aminopeptidase immunoreactivity is abundantly present in human hypothalamus and posterior pituitary gland, with reduced expression in paraventricular and suprachiasmatic neurons in chronic schizophrenia.

The vasopressin- and oxytocin-degrading enzyme insulin-regulated aminopeptidase (IRAP) is expressed in various organs including the brain. However, knowledge about its presence in human hypothalamus is fragmentary. Functionally, for a number of reasons (genetic linkage, hydrolysis of oxytocin and vasopressin, its role as angiotensin IV receptor in learning and memory and others) IRAP might play a role in schizophrenia. We studied the regional and cellular localization of IRAP in normal human brain with special emphasis on the hypothalamus and determined numerical densities of IRAP-expressing cells in the paraventricular, supraoptic and suprachiasmatic nuclei in schizophrenia patients and controls. By using immunohistochemistry and Western blot analysis, IRAP was immunolocalized in postmortem human brains. Cell countings were performed to estimate numbers and numerical densities of IRAP immunoreactive hypothalamic neurons in schizophrenia patients and control cases. Shape, size and regional distribution of IRAP-expressing cells, as well the lack of co-localization with the glia marker glutamine synthetase, show that IRAP is expressed in neurons. IRAP immunoreactive cells were observed in the hippocampal formation, cerebral cortex, thalamus, amygdala and, abundantly, hypothalamus. Double labeling experiments (IRAP and oxytocin/neurophysin 1, IRAP with vasopressin/neurophysin 2) revealed that IRAP is present in oxytocinergic and in vasopressinergic neurons. In schizophrenia patients, the numerical density of IRAP-expressing neurons in the paraventricular and the suprachiasmatic nuclei is significantly reduced, which might be associated with the reduction in neurophysin-containing neurons in these nuclei in schizophrenia. The pathophysiological role of lowered hypothalamic IRAP expression in schizophrenia remains to be established.

Measuring Cell Viscoelastic Properties Using a Microfluidic Extensional Flow Device.

The quantification of cellular mechanical properties is of tremendous interest in biology and medicine. Recent microfluidic technologies that infer cellular mechanical properties based on analysis of cellular deformations during microchannel traversal have dramatically improved throughput over traditional single-cell rheological tools, yet the extraction of material parameters from these measurements remains quite complex due to challenges such as confinement by channel walls and the domination of complex inertial forces. Here, we describe a simple microfluidic platform that uses hydrodynamic forces at low Reynolds number and low confinement to elongate single cells near the stagnation point of a planar extensional flow. In tandem, we present, to our knowledge, a novel analytical framework that enables determination of cellular viscoelastic properties (stiffness and fluidity) from these measurements. We validated our system and analysis by measuring the stiffness of cross-linked dextran microparticles, which yielded reasonable agreement with previously reported values and our micropipette aspiration measurements. We then measured viscoelastic properties of 3T3 fibroblasts and glioblastoma tumor initiating cells. Our system captures the expected changes in elastic modulus induced in 3T3 fibroblasts and tumor initiating cells in response to agents that soften (cytochalasin D) or stiffen (paraformaldehyde) the cytoskeleton. The simplicity of the device coupled with our analytical model allows straightforward measurement of the viscoelastic properties of cells and soft, spherical objects.

A flow visualization and superposition rheology study of shear-banding wormlike micelle solutions.

In this paper, we use rheometry and flow visualization to study the dynamics of the interface between shear bands in a wormlike micellar solution sheared between concentric cylinders, i.e., in a Taylor-Couette (TC) cell, and to evaluate the stress diffusion coefficient and the stress correlation length in the Johnson-Segalman model. Two wormlike micellar solutions are studied: an aqueous solution of CTAB-NaNO3 and a solution of CPCl-NaSal in brine. These systems are highly elastic, exhibit Maxwellian behavior in linear viscoelasticity experiments, and shear banding in nonlinear experiments [S. Lerouge, et al., Soft Matter, 2008, 4, 1808-1819, M. A. Fardin, et al., Soft Matter, 2012, 8(39), 10072-10089, P. Ballesta, et al., J. Rheol., 2007, 51, 1047]. A large, custom-built, computer controlled TC cell allows us to rotate both cylinders independently and to visualize the flow in the r-z plane using a CCD camera. At low shear rates, the flow is stable and the fluid appears homogeneous throughout the gap between the cylinders. Above a critical shear rate, a shear banding transition occurs. This manifests itself in the formation of two distinct bands in the r-z plane, with an interface between the two bands. For sufficiently high ramp speeds, multiple steps of interface evolution are identified, as noted by Radulescu, Lerouge, and others [O. Redulescu, et al., Europhys. Lett., 2003, 62, 230, S. Lerouge, et al., Soft Matter, 2008, 4, 1808-1819]. We quantify the interface travel using direct visualization and use this measure, as well as superposition rheometry [P. Ballesta, et al., J. Rheol., 2007, 51, 1047], to determine the stress diffusion coefficient D and the stress correlation length ζ in the Johnson-Segalman model. These parameters are evaluated at different temperatures, shear rates, and gap sizes. We find that the stress diffusion coefficient and the stress correlation length exhibit a strong dependence on the gap of the Taylor-Couette cell for both shear-banding systems. For the CTAB-NaNO3 system, we report a linear dependence of the stress diffusion coefficient on temperature for the parameter range considered. In addition, we find that for this system, the stress diffusion coefficient is independent of shear rate. For the CPCl-NaSal system, we observe the same color changes in the sample reported by others on extended light exposure; however, we find that different histories of light exposure do not affect the measured stress diffusion coefficient.

Experimental observation of the asymmetric instability of intermediate-reduced-volume vesicles in extensional flow.

Vesicles provide an attractive model system to understand the deformation of living cells in response to mechanical forces. These simple, enclosed lipid bilayer membranes are suitable for complementary theoretical, numerical, and experimental analysis. A recent study [Narsimhan, Spann, Shaqfeh, J. Fluid Mech., 2014, 750, 144] predicted that intermediate-aspect-ratio vesicles extend asymmetrically in extensional flow. Upon infinitesimal perturbation to the vesicle shape, the vesicle stretches into an asymmetric dumbbell with a cylindrical thread separating the two ends. While the symmetric stretching of high-aspect-ratio vesicles in extensional flow has been observed and characterized [Kantsler, Segre, Steinberg, Phys. Rev. Lett., 2008, 101, 048101] as well as recapitulated in numerical simulations by Narsimhan et al., experimental observation of the asymmetric stretching has not been reported. In this work, we present results from microfluidic cross-slot experiments observing this instability, along with careful characterization of the flow field, vesicle shape, and vesicle bending modulus. The onset of this shape transition depends on two non-dimensional parameters: reduced volume (a measure of vesicle asphericity) and capillary number (ratio of viscous to bending forces). We observed that every intermediate-reduced-volume vesicle that extends forms a dumbbell shape that is indeed asymmetric. For the subset of the intermediate-reduced-volume regime we could capture experimentally, we present an experimental phase diagram for asymmetric vesicle stretching that is consistent with the predictions of Narsimhan et al.

A novel prediction model for human papillomavirus-associated oropharyngeal squamous cell carcinoma using p16 and subcellular ß-catenin expression.

BACKGROUND: p16 overexpression is a highly sensitive yet moderately specific biomarker for predicting human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC). Nuclear ß-catenin translocation has been linked to HPV-positive OPSCC. However, whether the strategy of combining ß-catenin with p16 can better predict HPV-associated OPSCC remains unknown. METHODS: We evaluated the expression of p16 and ß-catenin (nuclear and membrane) by immunohistochemistry staining in 101 OPSCC tissues and HPV status by HPV DNA in situ hybridization. Logistic regression models were used to evaluate single or multiple biomarkers for HPV prediction. The prediction power, sensitivity, and specificity were determined by receiver operating characteristic (ROC) analyses. RESULTS: Our data showed that upon univariate analysis, p16 and nuclear ß-catenin were positively correlated with HPV status, while membrane ß-catenin was inversely correlated with HPV status (P < 0.01). p16 showed the highest HPV predictive power, with area under the curve (AUC) of 0.9074 compared to 0.6762 for nuclear ß-catenin and 0.7635 for membrane ß-catenin, respectively, indicating differential accuracies for HPV prediction. Multivariable analysis showed that p16 was significantly correlated with HPV, while nuclear and membrane ß-catenin showed marginal significance. The three-biomarker model was similarly sensitive (98.9% vs. 100%) but more specific (88.9% vs. 81%) than p16 alone, which also showed a good predictive value for overall (P = 0.0002) survival and disease-free (P = 0.0158) survival. CONCLUSION: Our study suggests a novel model of combining p16 and subcellular ß-catenin for prediction of HPV-associatred OPSCC, and this finding deserves further validation.

Human papillomavirus 16 oncoprotein regulates the translocation of ß-catenin via the activation of epidermal growth factor receptor.

BACKGROUND: To understand the mechanism of frequent and early lymph node metastasis in high-risk human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC), this study investigated whether ß-catenin is regulated by the HPV oncoprotein and contributes to OPSCC metastasis. METHODS: Expression levels of p16, ß-catenin, and epidermal growth factor receptor (EGFR) were examined in OPSCC samples (n = 208) by immunohistochemistry. The expression and subcellular localization of ß-catenin and EGFR activation were also studied in HPV-positive and HPV-negative head and neck squamous cell carcinoma cell lines with western blot analysis. HPV16 E6 small interfering RNA was used to elucidate the effect of the HPV oncoprotein on ß-catenin translocation. The involvement of EGFR in ß-catenin translocation was confirmed by treatment with erlotinib. Moreover, the invasive capacity was evaluated after HPV16 E6/E7 repression. RESULTS: The results showed that the membrane weighted index of ß-catenin was inversely correlated with p16 positivity (P < .001) and lymph node metastasis (P = .026), whereas nuclear staining of ß-catenin was associated with p16-positive OPSCC (P < .001). A low level of membrane ß-catenin expression was significantly associated with disease-free and overall survival (P < .0001 in both cases). Furthermore, the membrane weighted index of EGFR was inversely correlated with p16 positivity (P < .001) and positively correlated with membrane ß-catenin (P < .001). The in vitro study showed that HPV16 E6 repression led to reductions of phospho-EGFR and nuclear ß-catenin, which were also observed after erlotinib treatment, and inhibition of invasion. CONCLUSIONS: The findings suggest that HPV16 E6 mediates the translocation of ß-catenin to the nucleus, which may be regulated by activated EGFR.

Laryngeal papillomatosis associated dysplasia in the adult population: an update on prevalence and HPV subtyping.

OBJECTIVES: The objectives were to determine the prevalence of laryngeal dysplasia and associated human papilloma virus (HPV) subtypes in adult patients, 18 years or older, suffering from laryngeal papillomatosis at a tertiary care institution. STUDY DESIGN: Retrospective cohort study. METHODS: Patients with biopsy proven laryngeal papillomatosis were identified via chart review. All available pathology specimens were reviewed by a dedicated head and neck pathologist to confirm/refute the diagnosis of laryngeal dysplasia, and grade the level of dysplasia. Interrater agreement was compared using cross-tabulation methods. Specimens identified to be positive for dysplasia underwent further testing via in situ hybridization for low-risk (6/11) or high-risk (16/18) HPV subtypes. RESULTS: Of the 85 subjects identified to have laryngeal papillomatosis, 24(28%) demonstrated laryngeal dysplasia. There was good interrater agreement on the presence of dysplasia; however, there was only fair agreement on the grade of dysplasia. Of the pathology specimens tested for HPV subtype, the majority of patients (62%) were positive for HPV 6/11, including all high-grade dysplasia patients. Three (12%) dysplasia specimens were negative for both high- and low-risk HPV subtypes. CONCLUSIONS: We found a 28% prevalence of dysplasia in our patient population with the majority of patients positive for low-risk HPV subtypes indicating that high-risk HPV subtypes do not predispose laryngeal papilloma patients to dysplasia.

Roles of epithelial cell-derived periostin in TGF-beta activation, collagen production, and collagen gel elasticity in asthma.

Periostin is considered to be a matricellular protein with expression typically confined to cells of mesenchymal origin. Here, by using in situ hybridization, we show that periostin is specifically up-regulated in bronchial epithelial cells of asthmatic subjects, and in vitro, we show that periostin protein is basally secreted by airway epithelial cells in response to IL-13 to influence epithelial cell function, epithelial-mesenchymal interactions, and extracellular matrix organization. In primary human bronchial epithelial cells stimulated with periostin and epithelial cells overexpressing periostin, we reveal a function for periostin in stimulating the TGF-beta signaling pathway in a mechanism involving matrix metalloproteinases 2 and 9. Furthermore, conditioned medium from the epithelial cells overexpressing periostin caused TGF-beta-dependent secretion of type 1 collagen by airway fibroblasts. In addition, mixing recombinant periostin with type 1 collagen in solution caused a dramatic increase in the elastic modulus of the collagen gel, indicating that periostin alters collagen fibrillogenesis or cross-linking and leads to stiffening of the matrix. Epithelial cell-derived periostin in asthma has roles in TGF-beta activation and collagen gel elasticity in asthma.

Modelling the reopen strategy from dynamic zero-COVID in China considering the sequela and reinfection.

Although the dynamic zero-COVID policy has effectively controlled virus spread in China, China has to face challenges in balancing social-economic burdens, vaccine protection, and the management of long COVID symptoms. This study proposed a fine-grained agent-based model to simulate various strategies for transitioning from a dynamic zero-COVID policy with a case study in Shenzhen. The results indicate that a gradual transition, maintaining some restrictions, can mitigate infection outbreaks. However, the severity and duration of epidemics vary based on the strictness of the measures. In contrast, a more direct transition to reopening may lead to rapid herd immunity but necessitate preparedness for potential sequelae and reinfections. Policymakers should assess healthcare capacity for severe cases and potential long-COVID symptoms and determine the most suitable approach tailored to local conditions.

Impact of the COVID-19 pandemic on people in need of care or support: protocol for a SARS-CoV-2 registry.

INTRODUCTION: People in need of care or support are severely affected by the COVID-19 pandemic. We lack valid data of long-term assessments. We present a register study to detect the physical and psychosocial impact of the COVID-19 pandemic on people in need of care or support in Bavaria, Germany. To describe the persons' life conditions comprehensively, we assess the perspectives and needs of the respective care teams too. Results will serve as evidence-based source to manage the pandemic and long-term prevention strategies. METHODS AND ANALYSIS: The 'Bavarian ambulatory COVID-19 Monitor' is a multicentre registry including a purposive sample of up to 1000 patient-participants across three study sites in Bavaria. The study group consists of 600 people in need of care with a positive SARS-CoV-2 PCR test. Control group 1 comprises 200 people in need of care with a negative SARS-CoV-2 PCR test, while control group 2 comprises 200 people with a positive SARS-CoV-2 PCR test but are not in need of care. We assess the clinical course of infection, psychosocial aspects and care needs using validated measures. Follow-up is every 6 months for up to 3 years. Additionally, we assess up to 400 people linked to these patient-participants (caregivers, general practitioners (GPs)) for their health and needs. Main analyses are stratified by level of care I-V (I=minor/V=most severe impairment of independence), inpatient/outpatient care setting, sex and age. We use descriptive and inferential statistics to analyse cross-sectional data and changes over time. In qualitative interviews with 60 stakeholders (people in need of care, caregivers, GPs, politicians), we explore interface problems of different functional logics, of everyday and professional perspectives. ETHICS AND DISSEMINATION: The Institutional Review Board of the University Hospital LMU Munich (#20-860) and the study sites (Universities of Wurzburg and Erlangen) approved the protocol. We disseminate the results by peer-reviewed publications, international conferences, governmental reports, etc.

Recognition of nonkeratinizing morphology in oropharyngeal squamous cell carcinoma - a prospective cohort and interobserver variability study.

AIMS: Nonkeratinizing morphology in oropharyngeal squamous cell carcinoma (NKSCC) strongly correlates with human papillomavirus and p16 status, but as a unique diagnostic entity is not widely recognized by pathologists. We sought to prospectively examine the performance of a new histological typing system during 1 year of routine clinical practice (Aim 1) and also its reproducibility amongst six head and neck pathologists using a 40 case test set (Aim 2). METHODS AND RESULTS: The three histological types were: Type 1 (keratinizing), Type 2 (nonkeratinizing with maturation) and Type 3 (nonkeratinizing). For Aim 1, there were 85 cases. p16 immunohistochemistry was positive in five of the 18 (27.8%) cases classified as Type 1, 18 of the 19 (94.7%) as Type 2, and 47 of the 48 (97.9%) as Type 3. For Aim 2, agreement among pathologists on the test cases was best for types 1 and 3 (kappa values 0.62 and 0.56; P < 0.0001) and lowest for type 2 (kappa 0.35; P < 0.0001). All 21 cases classified as NK SCC (type 3) by any of the reviewers was p16 positive. CONCLUSIONS: Pathologists can recognize NK SCC with good agreement, and when a pathologist classifies a tumour as NK SCC, this reliably predicts p16 positivity.

Reduced density of hypothalamic VGF-immunoreactive neurons in schizophrenia: a potential link to impaired growth factor signaling and energy homeostasis.

Protein expression of VGF (nonacronymic) is induced by nerve/brain-derived growth factor, neurotrophin 3, and insulin. VGF is synthesized by neurons in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. After enzymatic processing, smaller VGF-derived peptides are secreted into the cerebrospinal fluid (CSF) or blood. These peptides play important roles by improving synaptic plasticity, neurogenesis, and energy homeostasis, which are impaired in schizophrenia. Based on previous observations of neuroendocrine and hypothalamic deficits in schizophrenia and to determine whether increased levels of the VGF fragment 23-62 in CSF, which have been described in a recent study, were related to changes in hypothalamic VGF expression, an immunohistochemical study was performed in 20 patients with schizophrenia and 19 matched control subjects. N- (D-20) and C-terminal (R-15) VGF antibodies yielded similar results and immunolabeled a vast majority of PVN and SON neurons. Additionally, D20-VGF immunohistochemistry revealed immunostained fibers in the pituitary stalk and neurohypophysis that ended at vessel walls, suggesting axonal transport and VGF secretion. The cell density of D20-VGF-immunoreactive neurons was reduced in the left PVN (P = 0.002) and SON (P = 0.008) of patients with schizophrenia. This study provides the first evidence for diminished hypothalamic VGF levels in schizophrenia, which might suggest increased protein secretion. Our finding was particularly significant in subjects without metabolic syndrome (patients with a body mass index ≤28.7 kg/m(2)). In conclusion, apart from beneficial effects on synaptic plasticity and neurogenesis, VGF may be linked to schizophrenia-related alterations in energy homeostasis.

Evaluation of an ameloblastic fibro-odontoma with cone beam computed tomography.

BACKGROUND: The clinical presentation, radiographic features, and histopathological findings of a case of ameloblastic fibro-odontoma are described. The clinical and radiographic presentations of this case are typical of this benign odontogenic tumor. The patient was young and asymptomatic with the exception of the clinical absence of the permanent mandibular left first molar. Treatment consisted of simple enucleation with removal of the primary mandibular left second molar. METHODS: A panoramic image and cone beam computed tomography (CBCT) scan were acquired in order to determine the reason for clinical absence of the permanent mandibular left first molar. The CBCT image proved to be a valuable supplement to the conventional radiographic examination as it provided information not apparent on the 2-dimensional panoramic image. Both the extent of the lesion and its effects on adjacent structures were better delineated with CBCT. Additionally, the presence of calcifications, an important radiographic characteristic of this particular lesion, were visible on CBCT versus the panoramic image. CONCLUSIONS: This case report demonstrates that the CBCT scan provided important management and treatment planning information that was not apparent in the panoramic image.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Tumours of the Oral Cavity and Mobile Tongue.

The fifth chapter of the upcoming fifth edition of the 2022 World Health Organization Classification of Tumours of the Head and Neck titled Tumours of the oral cavity and mobile tongue, has had some modifications from the 2017 fourth edition. A new section "Non-neoplastic Lesions", introduces two new entries: necrotizing sialometaplasia and melanoacanthoma. The combined Oral potentially malignant disorders and Oral epithelial dysplasia section in the 2015 WHO has now been separated and submucous fibrosis and HPV-associated dysplasia are also discussed in separate sections. Carcinoma cuniculatum and verrucous carcinoma are described in dedicated sections, reflecting that the oral cavity is the most common location in the head and neck for both these entities which have distinct clinical and histologic features from conventional squamous cell carcinoma. This review summarizes the changes in Chapter 5 with special reference to new additions, deletions, and sections that reflect current clinical, histological, and molecular advances.

Patterns of extralaryngeal spread of laryngeal cancer: thyroid cartilage penetration occurs in a minority of patients with extralaryngeal spread of laryngeal squamous cell cancers.

BACKGROUND: Laryngeal preservation programs for patients with advanced laryngeal squamous cell carcinomas (SCC) have generally excluded patients with T4 disease. The accuracy of preoperative imaging in evaluating thyroid cartilage penetration and extralaryngeal spread (ELS) has previously been questioned. Clinically, SCC spread into noncartilaginous structures may have less of a functional impact when compared with thyroid cartilage penetration. The current study was designed to characterize and quantify the routes and frequency of ELS. METHODS: A total of 103 laryngectomy specimens with preoperative contrast-enhanced neck computed tomography scans were coded according to the observed extent of disease by pathological and radiological data. Previously irradiated tumors or those of pyriform sinus origin were omitted. Routes of spread were categorized as anterior (thyroid cartilage penetration), posterior (arytenoid cartilage destruction and thyroarytenoid space widening), inferior (conus elasticus penetration), and superior (base of tongue, thyrohyoid membrane or thyroid notch penetration involvement). RESULTS: Sixty-three cases of ELS were identified. Anterior spread by thyroid cartilage penetration occurred in 44% of all instances of ELS, followed by both inferior and posterior spread each representing 33% of ELS cases. Superior spread occurred with a frequency of 24%. CONCLUSIONS: Although thyroid cartilage penetration is a common route of ELS of glottic and supraglottic SCC, ELS into surrounding structures with thyroid cartilage penetration was found to occur in only 44% of the cases of ELS in the current study. As illustrated, advanced SCC spreads in a variety of pathways. Once these patterns are better understood and identified at the time of initial evaluation, subgroups of patients with ELS who may still be candidates for laryngeal preservation may be identified.

Pathologic effects of external-beam irradiation on human vocal folds.

OBJECTIVES: We sought to better characterize pathologic changes that occur in the human vocal fold after radiotherapy for head and neck cancer. METHODS: In a blinded, controlled study of archived tissue, we evaluated postirradiation salvage laryngectomy vocal fold tissue without evidence of malignant disease. Clinical and demographic patient data were collected. In a blinded fashion, irradiated tissue was compared to nonirradiated, benign control tissue. Histomorphometric analysis was used to assess muscle and collagen organization, superficial lamina propria (SLP) and vocal ligament thickness, vocalis muscle fiber area, collagen content, and hyaluronic acid content. Immunohistochemical analysis was used to assess the content of type I collagen, type IV collagen, vimentin, fibronectin, alpha-smooth muscle actin, matrix metalloproteinase 9, and laminin. RESULTS: Twenty irradiated vocal folds were evaluated and compared to control specimens. Collagen and muscle disorganization was noted in the irradiated specimens. The SLP and vocal ligament thicknesses and the mean muscle fiber diameters did not differ significantly. The SLP fibronectin and the vocalis muscle and SLP collagen content were significantly increased in the irradiated vocal folds, and the SLP collagen content increased significantly with time between irradiation and resection. The laminin content of irradiated vocalis muscles was significantly decreased. CONCLUSIONS: Radiotherapy results in significant vocal fold tissue changes. Having more precisely defined these changes, we plan continued investigation seeking targeted preventive and therapeutic interventions for improved vocal quality following radiotherapy.

Peptide nucleic acids as tools for single-molecule sequence detection and manipulation.

The ability to strongly and sequence-specifically attach modifications such as fluorophores and haptens to individual double-stranded (ds) DNA molecules is critical to a variety of single-molecule experiments. We propose using modified peptide nucleic acids (PNAs) for this purpose and implement them in two model single-molecule experiments where individual DNA molecules are manipulated via microfluidic flow and optical tweezers, respectively. We demonstrate that PNAs are versatile and robust sequence-specific tethers.