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| {{CMG}}; {{AE}} {{chetan}} | | {{CMG}}; {{AE}} {{chetan}} |
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| ==Pathophysiology== | | ==Chest X-Rays== |
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| ====Diminished Mucociliary Clearance====
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| The [[Respiratory epithelium#Ciliary Escalator|cilia]] lining the [[respiratory epithelium]] serve to move secreted [[mucus]] containing trapped foreign particles including pathogens towards the [[oropharynx]] for either expectoration or swallowing. Elevated incidence of [[pneumonia]] in patients with genetic defects affecting [[mucociliary clearance]] such as [[primary ciliary dyskinesia]] suggests its role in the pathogenesis of community-acquired pneumonia.
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| ====Impaired Cough Reflex==== | | ==CT Images== |
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| [[Cough]], together with [[mucociliary clearance]], prevent pathogens from entering the lower [[respiratory tract]]. Cough suppression or [[cough reflex]] inhibition seen in patients with [[cerebrovascular accident]]s and [[overdose|drug overdosage]]s is associated with an enhanced risk for [[aspiration pneumonia]]. Another relation to [[cough]] is [[genetic polymorphism]]s in the [[angiotensin-converting enzyme|angiotensin-converting enzyme (ACE)]] gene. The role of [[cough]] in preventing [[pneumonia]] may be explained by a higher risk for developing [[pneumonia]] in [[homozygote]]s carrying [[deletion]]/[[deletion]] (DD) [[genotype]] who are found to have lower levels of [[bradykinin]] and [[tachykinins]] such as [[substance P]].<ref name="Morimoto-2002">{{Cite journal | last1 = Morimoto | first1 = S. | last2 = Okaishi | first2 = K. | last3 = Onishi | first3 = M. | last4 = Katsuya | first4 = T. | last5 = Yang | first5 = J. | last6 = Okuro | first6 = M. | last7 = Sakurai | first7 = S. | last8 = Onishi | first8 = T. | last9 = Ogihara | first9 = T. | title = Deletion allele of the angiotensin-converting enzyme gene as a risk factor for pneumonia in elderly patients. | journal = Am J Med | volume = 112 | issue = 2 | pages = 89-94 | month = Feb | year = 2002 | doi = | PMID = 11835945 }}</ref><ref>{{Cite journal | last1 = Rigat | first1 = B. | last2 = Hubert | first2 = C. | last3 = Alhenc-Gelas | first3 = F. | last4 = Cambien | first4 = F. | last5 = Corvol | first5 = P. | last6 = Soubrier | first6 = F. | title = An insertion/deletion polymorphism in the angiotensin I-converting enzyme gene accounting for half the variance of serum enzyme levels. | journal = J Clin Invest | volume = 86 | issue = 4 | pages = 1343-6 | month = Oct | year = 1990 | doi = 10.1172/JCI114844 | PMID = 1976655 }}</ref>
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| ====Defective Immnue System====
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| [[Pathogen-associated molecular pattern|Pathogen-associated molecular patterns (PAMPs)]] are initially recognized by [[Toll-like receptor|Toll-like receptors (TLRs)]] and other [[pattern recognition receptor|pattern-recognition receptors (PRRs)]] of the [[innate immune system]]. Effectors in the [[acquired immunity|acquired immune system]] are involved in elimination of microorganisms and generation of immunological memory. Other components in the immune system such as [[complement system]], [[cytokine]]s, and [[collectin]]s, also mediate the defense against microorganisms causing pneumonia.
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| ==References== | | ==References== |
Revision as of 18:48, 18 February 2014