Inflammatory changes such as subepithelial edema and excessive inflammatory cell infiltration have been observed in uvular tissues of obstructive sleep apnea (OSA) subjects. The levels of proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin-6 are elevated in the serum of apneic patients and have been proposed as mediators of muscle weakness. TNF-alpha has been shown to affect diaphragm contractility in mice and rabbit in vivo.
To assess total and compartmental TNF-alpha expression in uvular tissues of apneic and nonapneic patients.
Uvular tissues were collected from 14 snorers without sleep disorders breathing, 14 subjects with OSA (OSA 1 group) whose body mass index (BMI) was similar to that of snorers, and 12 additional obese OSA subjects (OSA 2 group) who underwent an uvulopalatopharyngoplasty. Sections were examined using immunohistochemistry and Western blot analysis. TNF-alpha expression was evaluated in the musculus uvulae (MU), epithelial layer, and perimuscular tissues from proximal uvular sections.
TNF-alpha was more highly expressed in whole uvular protein extracts of apneic groups than in snorers ([mean +/- SEM] snorers, 100.5 +/- 3.0%; OSA 1 group, 127.1 +/- 6.9%; OSA 2 group, 140.7 +/- 11.0%; p = 0.01). In the muscular area, TNF-alpha levels were higher in the more obese OSA subjects than in the other two groups (snorers, 100.3 +/- 3%; OSA 1 group, 107.4 +/- 0.7%; OSA 2 group, 124.1 +/- 4.2%; p = 0.007). In the muscular area, TNF-alpha was correlated with BMI, but no relationship was found with the apnea-hypopnea index.
We conclude that MU is the major TNF-alpha source in uvular tissue and that TNF-alpha is more highly expressed in the heaviest OSA patients compared to less obese OSA patients and nonapneic snorers.
"The UA mucosa in snorers is edematous, inflamed, and hyperplastic. The levels of proinflammatory cytokines TNF-α and IL-6 are elevated in the uvula of nonapneic snorers, although they are much higher in apneic patients . Snoring is associated with cytokine release from blood cells and promotion of inflammation . "
[Show abstract][Hide abstract] ABSTRACT: OSA is characterized by the quintessential triad of intermittent apnea, hypoxia, and hypoxemia due to pharyngeal collapse. This paper highlights the upstream mechanisms that may trigger cognitive decline in OSA. Three interrelated steps underpin cognitive dysfunction in OSA patients. First, several risk factors upregulate peripheral inflammation; these crucial factors promote neuroinflammation, cerebrovascular endothelial dysfunction, and oxidative stress in OSA. Secondly, the neuroinflammation exerts negative impact globally on the CNS, and thirdly, important foci in the neocortex and brainstem are rendered inflamed and dysfunctional. A strong link is known to exist between neuroinflammation and neurodegeneration. A unique perspective delineated here underscores the importance of dysfunctional brainstem nuclei in etiopathogenesis of cognitive decline in OSA patients. Nucleus tractus solitarius (NTS) is the central integration hub for afferents from upper airway (somatosensory/gustatory), respiratory, gastrointestinal, cardiovascular (baroreceptor and chemoreceptor) and other systems. The NTS has an essential role in sympathetic and parasympathetic systems also; it projects to most key brain regions and modulates numerous physiological functions. Inflamed and dysfunctional NTS and other key brainstem nuclei may play a pivotal role in triggering memory and cognitive dysfunction in OSA. Attenuation of upstream factors and amelioration of the NTS dysfunction remain important challenges.
[Show abstract][Hide abstract] ABSTRACT: A general model of the multiple-winding coupled inductor is
described, in which all parameters can be directly measured. The
magnetics and the resulting cross-regulation models are employed in a
tutorial explanation of the mechanisms by which leakage inductances and
effective turns ratios affect cross regulation and discontinuous
conduction mode boundaries in a multiple-output converter with arbitrary
number of outputs. Analytical results are found for the discontinuous
mode boundaries and for the steady-state characteristics when one of the
outputs operates in discontinuous conduction mode. Three basic
approaches to coupled-inductor design are compared: near-ideal coupling,
practical moderate coupling, and the zero-ripple approach. It is shown
that the best cross regulation can be obtained via the zero-ripple
approach with relatively loose coupling in applications where there is
at least one output whose load current variations are relatively small
so that all windings can always operate in continuous conduction mode.
The conclusions are supported by experimental results
IEEE Transactions on Power Electronics 08/2000; 15(4-15):607 - 615. DOI:10.1109/63.849030 · 6.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Die obstruktive Schlafapnoe (OSA) ist in der westlichen Gesellschaft weit verbreitet und hat eine Prävalenz von 20 % für die
milde OSA und von 6–7 % für die mittelschwere bis schwere OSA (1). Die Prävalenz steigt bis zu einem Alter von 65 Jahren an
(2). Einer aktuellen Arbeit zufolge haben weibliche Schlafapnoiker im Vergleich zu Männern einen höheren Body-Mass-Index (BMI),
eine geringer ausgeprägte Tagesschläfrigkeit, weniger Atempausen und benötigen einen geringeren effektiven Beatmungsdruck
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