Insights from 3D modeling and fluid dynamics in COVID-19 pneumonia.

We address the lack of research regarding aerodynamic events behind respiratory distress at COVID-19. The use of chest CT enables quantification of pneumonia extent; however, there is a paucity of data regarding the impact of airflow changes. We reviewed 31 COVID-19 patients who were admitted in March 2020 with varying severity of pulmonary disease. Lung volumes were segmented and measured on CT images and patient-specific models of the lungs were created. Incompressible, laminar, and three-dimensional Navier-Stokes equations were used for the fluid dynamics (CFD) analyses of ten patients (five mild, five pneumonia). Of 31 patients, 17 were female, 18 had pneumonia, and 2 were deceased. Effective lung volume decreased in the general group, but the involvement of the right lung was prominent in dyspnea patients. CFD analyses revealed that the mass flow distribution was significantly distorted in pneumonia cases with diminished flow rate towards the right lung. In addition, the distribution of flow parameters showed mild group had less airway resistance with higher velocity (1.228 m/s vs 1.572 m/s) and higher static pressure values at airway branches (1.5112 Pa vs 1.3024 Pa). Therefore, we conclude that airway resistance and mass flow rate distribution are as important as the radiological involvement degree in defining the disease severity.

CIRCULATING MIR-132, MIR-146A, MIR-222, AND MIR-320 EXPRESSION IN DIFFERENTIAL DIAGNOSIS OF WOMEN WITH POLYCYSTIC OVARY SYNDROME.

Purpose: The aim of the study was to investigate whether the circulating miR-132, miR-146a, miR-222, and miR-320 levels are used in the differential diagnosis of women with polycystic ovary syndrome (PCOS) and healthy women. Methods: This prospective case-control study included 50 women with PCOS and age- and body mass index- matched 50 healthy controls. The hormone and lipid profiles, levels of microRNAs (miRNAs), and parameters of carbohydrate metabolism were measured. Results: Expression levels of miRNAs were assessed using the two-step quantitative real-time polymerase chain reaction. Circulating miR-132, miR-146a and miR-222 levels were significantly downregulated in the PCOS group compared with the control group. The miR-320 levels did not differ between the two groups. Free testosterone was negatively correlated with miR-132, miR-146a and miR-222. Insulin was negatively correlated with miR-132 and miR-146a. Conclusions: The results of the study revealed that miRNA expression, may suggest a possible distinction between healthy women and PCOS patients. miR-132, miR-146a, and miR-222 may have key functions in the pathogenesis of PCOS.

The clinical spectrum of xanthomatous lesions of the eyelids.

Yellowish papules, nodules, or plaques, namely "xanthomatous" lesions, may be seen on the eyelids in the course of various disorders. The prototype is "xanthelasma palpebrarum" (XP) that is localized only to the eyelids and may be associated with hyperlipidemia. On the other hand, different types of normolipemic disorders may also cause xanthomatous eyelid lesions. Among these, Langerhans cell histiocytosis, diffuse normolipemic xanthoma, and non-Langerhans cell histiocytoses (papular xanthoma, juvenile xanthogranuloma, xanthoma disseminatum, adult-onset xanthogranuloma, adult-onset asthma and periocular xanthogranuloma, necrobiotic xanthogranuloma, Erdheim-Chester disease, Rosai-Dorfman disease, and reticulohistiocytosis) can be listed. The eyelid findings of this heterogeneous group of disorders are challenging to differentiate from each other due to common clinical aspects that may even sometimes mimic XP. Nodularity, induration, ulceration, diffuse eyelid involvement, and extension from eyelids to the neighboring skin may represent the clinical features of xanthomatous lesions other than XP. It is necessary to obtain a thorough history and exclude XP and then perform detailed dermatological and systemic examination, biopsy for histopathologic confirmation, and appropriate specific imaging screens. As some of the conditions may be associated with other systemic disorders, especially malignancies, the differentiation of xanthomatous eyelid lesions has a critical importance, and clinical signs can be guiding.

Effect of glottic geometry on breathing: three-dimensional unsteady numerical simulation of respiration in a case with congenital glottic web.

Glottic obstruction is a major cause of dyspnea. Without understanding the normal function of the glottis in breathing, treating dyspnea does not restore normal physiology. Therefore, we designed a computational fluid dynamics (CFD) model that tested the respiratory cycle in larynges with normal glottis and congenital glottic web (CGW). A CGW case and a control subject (CC) were selected from the computed tomography (CT) archive. 3D computational models of the larynges with structured boundary layer were constructed from axial CT images after mesh refinement study. CFD analyses were based on the Reynolds-averaged Navier-Stokes approach. Incompressible flow solver (pressure-based) and SST k-w turbulence model were chosen for this study. To simulate a real-time breathing process, time varying flow rate boundary condition was derived from the spirometer of a healthy, non-smoking woman. Glottic areas were measured as 51.64 and 125.43 mm(2) for the CGW patient and CC, respectively. Time-dependent velocity contours and streamlines for the CC and CGW patient were drawn. The CC showed uniform flow, all through the inspiration and expiration phases. However, the CGW patient showed separation of flow at the glottis level, which caused areas of stagnation in the supraglottis (during expiration) and the subglottis and trachea (during inspiration). Specialized geometry of the normal larynx maintained uniform flow with low shear stress values on the wall even at high mass flow rates. Distortion of this geometry may cause obstruction of flow at multiple levels and, therefore, should be evaluated at multiple levels.

Non-typical morphology and localization in Turkish atopic dermatitis patients with onset before the age of 18 years.

BACKGROUND: Hanifin and Rajka's criteria (HRC) are the gold standard for the diagnosis of atopic dermatitis (AD). Apart from the age-related distribution and typical morphology of the lesions as defined in one of the major criteria of HRC, patients may also show nontypical morphology and localization. AIM: The aim of this study was to find the frequency of nontypical morphology and localization in Turkish AD patients with onset before the age of 18 years, who were diagnosed according to HRC. METHODS: This was a methodological study based on the analysis of patients' data derived from the checklists of HRC and precise clinical documentation of each patient. A total of 321 Turkish patients diagnosed between 1996 and 2004 with the onset of AD before the age of 18 years were allocated to the study group. RESULTS: 49.5% of patients had nontypical localization of AD, the majority being infants or children who had flexural involvement rather than the typical cheek or extremity lesions. Lichenified/exudative eczematous pattern was the most frequent morphologic type (45.5%); however, 54.5% of the patients showed combined or isolated variants, e.g. nummular and seborrheic patterns, in particular. CONCLUSIONS: A considerable amount of Turkish patients with AD before the age of 18 years presented with nontypical morphology and/or localization according to their age group. The confirmation of our findings in a multicentric prospective study would further allow a completion and correction of the diagnostic criteria of AD for age groups.

A computational study on the characteristics of airflow in bilateral abductor vocal fold immobility.

OBJECTIVES/HYPOTHESIS: To evaluate airway sufficiency and airflow dynamics in a group of patients who underwent a posterior transverse laser cordotomy (PTLC) procedure. STUDY DESIGN: Mixed methods research, university hospital setting. METHODS: Sixteen patients who underwent a PTLC procedure volunteered to be involved in this study. Dyspnea levels, voice, and glottic opening in indirect laryngoscopy were evaluated subjectively. The airway was evaluated objectively by pulmonary function tests, and glottic areas were measured from axial computed tomography (CT) images. The control group consisted of 63 subjects from the tomography archive. For computational fluid dynamics (CFD) analyses, two subjects from the study group were chosen on the basis of obstruction level, and a normal female subject was selected from the control group. Cartesian coordinates for airway boundaries were determined from axial CT images, and a three-dimensional computational model of the larynx was constructed. Flow simulations were performed with two different flow conditions during inspiration. Comparison of velocity, static pressure, turbulence intensity, and wall shear stress distribution values were made between selected cases and control. RESULTS: Pulmonary data varied widely and did not correlate with the size of the glottic area or dyspnea level. CFD analyses revealed that in addition to obstruction at the glottic level, aerodynamic properties of the larynx are altered due to loss in muscular tonus. Also, the contour of the glottic opening was found to be very important in determining the character of airflow as laminar or turbulent. CONCLUSIONS: Patients have considerable differences in their flow patterns and force distributions during respiration. Patient-specific models may help in evaluation and treatment planning.