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Zinan Yang – One of the best experts on this subject based on the ideXlab platform.

  • cervical metastases from squamous cell carcinoma of hard palate and maxillary Alveolus a retrospective study of 10 years
    Head and Neck-journal for The Sciences and Specialties of The Head and Neck, 2014
    Co-Authors: Zinan Yang, Runzhi Deng, Guowen Sun, Xiaofeng Huang, Enyi Tang
    Abstract:

    Background The purpose of this study was to investigate the incidence of cervical metastasis in squamous cell carcinoma (SCC) of hard palate and maxillary Alveolus and to define its impact factors. Methods We conducted a retrospective study of patients surgically treated for SCC of hard palate and maxillary Alveolus from 2002 to 2011. In situ hybridization was performed to detect high-risk human papillomavirus (HPV) infection. Results The incidences of cervical metastasis and occult metastasis were 17.2% (11/64) and 9.8% (5/51), respectively. The pT classification and vascular invasion were correlated with cervical metastasis. Occult metastatic risk was significantly higher among patients with pT4. Presence of positive nodes impaired prognosis significantly. Conclusion SCC of hard palate and maxillary Alveolus has nonnegligible incidences of both overall and occult metastasis, which were highly associated with pT classification. We recommend routine, synchronous elective neck dissection for T4 lesions, whereas observation is an alternative for T1 to T3 lesions. © 2013 Wiley Periodicals, Inc. Head Neck 36: 969–975, 2014

  • Cervical metastases from squamous cell carcinoma of hard palate and maxillary Alveolus: a retrospective study of 10 years.
    Head & neck, 2013
    Co-Authors: Zinan Yang, Runzhi Deng, Guowen Sun, Xiaofeng Huang, Enyi Tang
    Abstract:

    BACKGROUND The purpose of this study was to investigate the incidence of cervical metastasis in squamous cell carcinoma (SCC) of hard palate and maxillary Alveolus and to define its impact factors. METHODS We conducted a retrospective study of patients surgically treated for SCC of hard palate and maxillary Alveolus from 2002 to 2011. In situ hybridization was performed to detect high-risk human papillomavirus (HPV) infection. RESULTS The incidences of cervical metastasis and occult metastasis were 17.2% (11/64) and 9.8% (5/51), respectively. The pT classification and vascular invasion were correlated with cervical metastasis. Occult metastatic risk was significantly higher among patients with pT4. Presence of positive nodes impaired prognosis significantly. CONCLUSION SCC of hard palate and maxillary Alveolus has nonnegligible incidences of both overall and occult metastasis, which were highly associated with pT classification. We recommend routine, synchronous elective neck dissection for T4 lesions, whereas observation is an alternative for T1 to T3 lesions.

Enyi Tang – One of the best experts on this subject based on the ideXlab platform.

  • cervical metastases from squamous cell carcinoma of hard palate and maxillary Alveolus a retrospective study of 10 years
    Head and Neck-journal for The Sciences and Specialties of The Head and Neck, 2014
    Co-Authors: Zinan Yang, Runzhi Deng, Guowen Sun, Xiaofeng Huang, Enyi Tang
    Abstract:

    Background The purpose of this study was to investigate the incidence of cervical metastasis in squamous cell carcinoma (SCC) of hard palate and maxillary Alveolus and to define its impact factors. Methods We conducted a retrospective study of patients surgically treated for SCC of hard palate and maxillary Alveolus from 2002 to 2011. In situ hybridization was performed to detect high-risk human papillomavirus (HPV) infection. Results The incidences of cervical metastasis and occult metastasis were 17.2% (11/64) and 9.8% (5/51), respectively. The pT classification and vascular invasion were correlated with cervical metastasis. Occult metastatic risk was significantly higher among patients with pT4. Presence of positive nodes impaired prognosis significantly. Conclusion SCC of hard palate and maxillary Alveolus has nonnegligible incidences of both overall and occult metastasis, which were highly associated with pT classification. We recommend routine, synchronous elective neck dissection for T4 lesions, whereas observation is an alternative for T1 to T3 lesions. © 2013 Wiley Periodicals, Inc. Head Neck 36: 969–975, 2014

  • Cervical metastases from squamous cell carcinoma of hard palate and maxillary Alveolus: a retrospective study of 10 years.
    Head & neck, 2013
    Co-Authors: Zinan Yang, Runzhi Deng, Guowen Sun, Xiaofeng Huang, Enyi Tang
    Abstract:

    BACKGROUND The purpose of this study was to investigate the incidence of cervical metastasis in squamous cell carcinoma (SCC) of hard palate and maxillary Alveolus and to define its impact factors. METHODS We conducted a retrospective study of patients surgically treated for SCC of hard palate and maxillary Alveolus from 2002 to 2011. In situ hybridization was performed to detect high-risk human papillomavirus (HPV) infection. RESULTS The incidences of cervical metastasis and occult metastasis were 17.2% (11/64) and 9.8% (5/51), respectively. The pT classification and vascular invasion were correlated with cervical metastasis. Occult metastatic risk was significantly higher among patients with pT4. Presence of positive nodes impaired prognosis significantly. CONCLUSION SCC of hard palate and maxillary Alveolus has nonnegligible incidences of both overall and occult metastasis, which were highly associated with pT classification. We recommend routine, synchronous elective neck dissection for T4 lesions, whereas observation is an alternative for T1 to T3 lesions.

Akira Tsuda – One of the best experts on this subject based on the ideXlab platform.

  • a cyclic model for particle motion in the pulmonary acinus
    Journal of Fluid Mechanics, 2006
    Co-Authors: S Haber, Akira Tsuda
    Abstract:

    A simplified model for the pulmonary Alveolus that imitates the rhythmical expansion of the Alveolus and the periodic shear flow in the adjacent airway is explored. The model consists of two eccentric cylinders and incompressible fluid that occupies the gap between them. The two cylinders undergo a simultaneous rhythmical expansion and contraction (mimicking the Alveolus expansion) while the inner cylinder performs a periodic rotation about its axis (inducing shear flow mimicking airway ductal flow). An analytical solution is obtained for the creeping flow induced by the simultaneously expanding cylinders. It is shown that above a certain critical value of rotation to expansion velocity ratio, the flow exhibits characteristic features such as a saddle point and closed streamlines about a centre, similar to those existing inside a single Alveolus during inhalation and exhalation. Poincar´ e maps of the trajectories of fluid particles demonstrate that, under various flow conditions, chaotic trajectories may exist, provided that expansion and rotation are slightly out of phase. This is similar to normal breathing conditions where the periodic expansion of the Alveolus and the tidal flow (i.e. shear flow above the mouth of the Alveolus) may be slightly out of phase. A novel definition of overall convective mixing efficiency is also suggested that inherently discounts reversible processes that do not contribute to mixing. It is demonstrated that two different convective mechanisms, related to the irreversibility of exhalation and inhalation and the onset of chaos, govern mixing efficiency in lung alveoli.

  • Gravitational deposition in a rhythmically expanding and contracting Alveolus.
    Journal of applied physiology (Bethesda Md. : 1985), 2003
    Co-Authors: Shimon Haber, Dror Yitzhak, Akira Tsuda
    Abstract:

    In a previous simulation, our laboratory demonstrated that the flow induced by a rhythmically expanding and contracting Alveolus is highly complex (Haber S, Butler JP, Brenner H, Emanuel I, and Tsu…

  • the effect of flow generated by a rhythmically expanding pulmonary acinus on aerosol dynamics
    Journal of Aerosol Science, 1998
    Co-Authors: S Haber, Akira Tsuda
    Abstract:

    Abstract The effects of a rhythmically expanding Alveolus on aerosol kinematics is investigated. The Alveolus and alveolar duct are modeled as cyclically self-similar expanding, spherical cap attached at its rim to a circular opening in an expanding plane. The flow induced by the alveolar wall motion plays a significant role in determining aerosol trajectories and deposition location. Under the combined effects of the flow and gravity, particles of 0.5–2  μ m in diameter tend to form a two-peaks deposition distribution over the alveolar walls; one peak is formed near the alveolar opening and the other around the alveolar center. This is markedly different from the single-peaked deposition pattern, where higher deposition concentration is observed at the alveolar center, in a simulation performed in the absence of alveolar wall motion. In addition, wall motion has a pronounced effect on particle residence time inside the Alveolus. For a given set of physiological conditions, particles tend to stay more than ten times longer before colliding with the Alveolus wall, due to their cyclic excursions. In microgravity circumstances (e.g. in space), the simulation shows that 10  μ m particles initially placed outside the Alveolus tend to slowly migrate away from it, while particles placed initially inside the Alveolus tend to cross streamlines due to inertial effects and subsequently deposit on the alveolar walls after a large number of breathing periods.

André Dagenais – One of the best experts on this subject based on the ideXlab platform.

  • The alveolar type I cells : the new knight of the Alveolus?
    The Journal of Physiology, 2006
    Co-Authors: Yves Berthiaume, Grégory Voisin, André Dagenais
    Abstract:

    Until recently our knowledge of the function and regulation of the alveolar type I cells has been relatively modest. They cover 95% of the alveolar surface and form a tight epithelial barrier along with the alveolar type II cells that helps keep the alveoli dry. It is also recognized that its special morphological characteristics are perfectly designed for efficient gas exchange between the Alveolus and the pulmonary capillaries. Much more is known about the function of the alveolar type II cells, which cover the remaining 5% of the alveolar surface. Mason & Williams (1977) described the type II cells as the ‘crenated tower’ defending the Alveolus. This concept has since been supported by extensive data demonstrating that the type II cell has multiple functions in addition to its traditionally recognized role in surfactant secretion (Fehrenbach, 2001). It is now well accepted that the alveolar type II cell plays an important role in fluid balance across the Alveolus and is actively involved in ion transport across the alveolar epithelium (Berthiaume et al. 1999). It also plays an important role in the repair process following injury, since it can proliferate and differentiate into alveolar type I cells (Berthiaume et al. 1999). Finally, the type II cell is known to play a major role in immunological defence of the Alveolus, by secreting various cytokines involved in the recruitment of inflammatory cells in the lung (Fehrenbach, 2001).

Ajay K. Prasad – One of the best experts on this subject based on the ideXlab platform.

  • flow and particle dispersion in a pulmonary Alveolus part i velocity measurements and convective particle transport
    Journal of Biomechanical Engineering-transactions of The Asme, 2010
    Co-Authors: Sudhaker Chhabra, Ajay K. Prasad
    Abstract:

    The alveoli are the smallest units of the lung that participate in gas exchange. Although gas transport is governed primarily by diffusion due to the small length scales associated with the acinar region (~500 μm), the transport and deposition of inhaled aerosol particles are influenced by convective airflow patterns. Therefore, understanding alveolar fluid flow and mixing is a necessary first step toward predicting aerosol transport and deposition in the human acinar region. In this study, flow patterns, and particle transport have been measured using a simplified in-vitro alveolar model consisting of a single Alveolus located on a bronchiole. The model comprises a transparent elastic 5/6 spherical cap (representing the Alveolus) mounted over a circular hole on the side of a rigid circular tube (representing the bronchiole). The Alveolus is capable of expanding and contracting in phase with the oscillatory flow through the tube. Realistic breathing conditions were achieved by exercising the model at physiologically relevant Reynolds and Womersley numbers. Particle image velocimetry was used to measure the resulting flow patterns in the Alveolus. Data were acquired for five cases obtained as combinations of the alveolar-wall motion (nondeforming/oscillating) and the bronchiole flow (none/ steady/oscillating). Detailed vector maps at discrete points within a given cycle revealed flow patterns, and transport and mixing of bronchiole fluid into the alveolar cavity. The time-dependent velocity vector fields were integrated over multiple cycles to estimate particle transport into the alveolar cavity and deposition on the alveolar wall. The key outcome of the study is that alveolar-wall motion enhances mixing between the bronchiole and the alveolar fluid. Particle transport and deposition into the alveolar cavity are maximized when the alveolar wall oscillates in tandem with the bronchiole fluid, which is the operating case in the human lung. [DOI: 10.1115/1.4001112].

  • Flow and Particle Dispersion in a Pulmonary Alveolus—Part I: Velocity Measurements and Convective Particle Transport
    Journal of biomechanical engineering, 2010
    Co-Authors: Sudhaker Chhabra, Ajay K. Prasad
    Abstract:

    The alveoli are the smallest units of the lung that participate in gas exchange. Although gas transport is governed primarily by diffusion due to the small length scales associated with the acinar region (~500 μm), the transport and deposition of inhaled aerosol particles are influenced by convective airflow patterns. Therefore, understanding alveolar fluid flow and mixing is a necessary first step toward predicting aerosol transport and deposition in the human acinar region. In this study, flow patterns, and particle transport have been measured using a simplified in-vitro alveolar model consisting of a single Alveolus located on a bronchiole. The model comprises a transparent elastic 5/6 spherical cap (representing the Alveolus) mounted over a circular hole on the side of a rigid circular tube (representing the bronchiole). The Alveolus is capable of expanding and contracting in phase with the oscillatory flow through the tube. Realistic breathing conditions were achieved by exercising the model at physiologically relevant Reynolds and Womersley numbers. Particle image velocimetry was used to measure the resulting flow patterns in the Alveolus. Data were acquired for five cases obtained as combinations of the alveolar-wall motion (nondeforming/oscillating) and the bronchiole flow (none/ steady/oscillating). Detailed vector maps at discrete points within a given cycle revealed flow patterns, and transport and mixing of bronchiole fluid into the alveolar cavity. The time-dependent velocity vector fields were integrated over multiple cycles to estimate particle transport into the alveolar cavity and deposition on the alveolar wall. The key outcome of the study is that alveolar-wall motion enhances mixing between the bronchiole and the alveolar fluid. Particle transport and deposition into the alveolar cavity are maximized when the alveolar wall oscillates in tandem with the bronchiole fluid, which is the operating case in the human lung. [DOI: 10.1115/1.4001112].