***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: Background —Limited prospect i ve epidemiological data are available on the relation between exposure to Chlamydia pneumoniae , Helicobacter pylori , cytomegalovirus ( CMV ) , and hepatitis A virus ( HAV ) , individually or as a total pathogen score , and human cardiovascular ( CV ) disease . Methods and Results —We analyzed enrollment sera from 3168 Canadian patients in the Heart Outcomes Prevention Evaluation ( HOPE ) study for antibodies to C pneumoniae , H pylori , CMV , and HAV and measured the relation between serostatus and 494 adjudicated trial outcomes of myocardial infa rct ion , stroke , or CV death over 4.5 years of follow-up . CV events were associated with CMV serostatus ( covariate-adjusted hazard ratio [ HR ] , 1.24 ; 95 % CI , 1.01 , 1.53 ) . Neither C pneumoniae IgG ( adjusted HR , 0.87 ; 95 % CI , 0.68 , 1.10 ) , C pneumonia IgA ( adjusted HR , 1.10 ; 95 % CI , 0.90 , 1.34 ) , H pylori IgG ( HR , 0.99 ; 95 % CI , 0.82 , 1.19 ) , nor HAV IgG ( HR , 1.01 ; 95 % CI , 0.83 , 1.24 ) predicted CV events . Total pathogen score was associated with CV events ( adjusted HR for 4 versus 1 or 0=1.41 ; 95 % CI , 1.02 , 1.96 ) . Conclusions —Exposure to CMV but not to C pneumoniae , H pylori , or HAV was associated with a slight excess risk of subsequent myocardial infa rct ion , stroke , or CV death in HOPE study patients , and total pathogen score based on these infections predicted a small increased hazard of CV events Retrospective and cross-sectional studies have suggested that both bacterial and viral infections may be risk factors for atherosclerosis , ischemic stroke and acute coronary events . The correlation between Chlamydia pneumoniae and atherosclerosis remains a source of controversy . Our case-control study is aim ed at evaluating the frequency of C. pneumoniae infection in a cohort of young adults with recent cerebrovascular disease and in particular etiologic stroke subtypes . Chlamydia pneumoniae IgG , IgM and IgA antibodies were evaluated by microimmunofluorescence method and antibody titers to both recombinant antigens chlamydial outer protein 2 and 60-kDa chlamydial heat shock protein ( HSP60 ) by ELISA . The two groups differed with regard to the prevalence of C. pneumoniae IgA ( P < 0.001 ) and IgG ( P < 0.0001 ) , as well as the titer of anti-R-HSP60 IgG ( P < 0.001 ) . We found an increase in IgA titers , suggestive of persistent , chronic active infection , in 16 patients in whom the etiology of the cerebral ischemic event was large-vessel atherothrombosis . Persistent , active C. pneumoniae infection may be an additional risk factor for ischemic stroke mainly of atherotrombotic origin in young subjects . However , a large-scale prospect i ve confirmation of our findings is required BACKGROUND AND PURPOSE An association between high lipoprotein(a ) [ Lp(a ) ] levels and positive Chlamydia pneumoniae IgG titers in coronary artery disease has been described . The possibility of predicting ischemic stroke by measurements of plasma Lp(a ) and C pneumoniae antibodies was investigated . METHODS This incident case-control study included 101 case subjects ( cases ) who had suffered ischemic cerebral infa rct ions and 201 matched control subjects ( controls ) . The study population was nested within the Västerbotten Intervention Program or the WHO MONICA project . Plasma sample s were measured for C pneumoniae-specific IgG and IgA antibodies and Lp(a ) .  RESULTS A significantly higher mean Lp(a ) level was found in female cases than in female controls . However , plasma Lp(a ) was unable to predict ischemic cerebral infa rct ions in either women or men . The proportion of individuals with positive C pneumoniae-specific IgG or IgA titers did not differ between cases and controls . Antibody titers were unable to predict a future stroke . The proportion of individuals with a positive C pneumoniae IgG titer in combination with a high Lp(a ) level did not differ significantly between cases and controls . CONCLUSIONS These data suggest that there is no association between baseline plasma Lp(a ) levels , presence of C pneumoniae antibodies , and future ischemic cerebral infa rct ions . Furthermore , no evidence of an interactive effect between high Lp(a ) levels and C pneumoniae IgG titers was found . However , selection bias and a recent C pneumoniae epidemic may have influenced the results Background and Purpose — Serologic evidence of infection with Chlamydia pneumoniae has been associated with cardiovascular disease , but its relationship with stroke risk remains uncertain . The objective of this study is to determine whether serological evidence of C pneumoniae infection is associated with risk of ischemic stroke . Methods — A population -based case-control study was performed in an urban , multiethnic population . Cases ( n=246 ) had first ischemic stroke , and controls ( n=474 ) matched for age , sex , and race – ethnicity were derived through r and om-digit dialing . Titers of C pneumoniae – specific IgG and IgA antibodies were measured using microimmunofluorescence , and positive titers were prospect ively defined . Conditional logistic regression was used to calculate odds ratios ( ORs ) and 95 % CIs adjusting for medical , behavioral , and socioeconomic factors . Results — Mean age among cases was 72.3±9.7 years ; 50.8 % were women .  Elevated C pneumoniae IgA titers were associated with increased risk of ischemic stroke after adjusting for hypertension , diabetes mellitus , current cigarette use , atrial fibrillation , and levels of high-density lipoprotein and low-density lipoprotein ( adjusted OR , 1.5 ; 95 % CI , 1.0 to 2.2 ) . Elevated IgG titers were not associated with stroke risk ( adjusted OR , 1.2 ; 95 % CI , 0.8 to 1.8 ) . There was a trend toward an association of elevated IgA titers with atherosclerotic and lacunar stroke but less so cardioembolic or cryptogenic subtypes . Conclusions — Serologic evidence of C pneumoniae infection is associated with ischemic stroke risk . IgA titers may be a better marker of risk than IgG. This association is independent of other stroke risk factors and is present for atherosclerotic , lacunar , and cardioembolic subypes . Further studies of the effect of C pneumoniae on stroke risk are warranted Background and Purpose : Chlamydia pneumoniae infection or exposure to C. pneumoniae was implicated as a risk factor for ischemic stroke . Our aim was to evaluate prospect ively the association between the presence of antibodies to C. pneumoniae ( IgG and IgA ) and the risk of incident ischemic stroke  among patients with pre-existing vascular disease . Methods : Sera were collected from 3,090 coronary heart disease patients enrolled in a secondary prevention trial . We measured baseline antibodies ( IgG and IgA ) in the sera of patients who developed subsequent ischemic strokes ( cases , n = 134 ) during follow-up ( mean 8.2 years ) , and in 134 age- and gender-matched pairs without subsequent stroke or myocardial infa rct ion . Results : The crude relative odds ( 95%CI ) of incident ischemic strokes in seropositive patients at baseline ( > 1.1 relative value units ) were 1.29 ( 95%CI , 0.69–2.47 ) for IgG and 1.31 ( 95 % CI , 0.69–2.55 ) for IgA by matched-pair analyses , and 1.42 ( 95%CI , 0.69–2.98 ) for IgG and 1.57 ( 95%CI , 0.76–3.35 ) for IgA after adjustments for conventional risk factors and the inflammatory marker , soluble intercellular adhesion molecule-1 . We explored the possibility that the risk of ischemic stroke may increase in parallel to increasing antibody titers , but did not demonstrate any significant association . Conclusions : Serological evidence for prior infection with C. pneumoniae did not emerge as an independent risk factor for incident ischemic stroke among patients at high risk due to pre-existing vascular disease Backgrouncd/ Objective Few studies have attempted to vali date the “ lacunar hypothesis . ” The accuracy of identifying lacunar and other nonlacunar mechanisms of infa rct ion will be increasingly important in evaluating potential stroke treatments . The aim of this study was to determine the value of lacunar syndromes in predicting radiologic lacunes and the value of clinicoradiologic lacunes in predicting “ lacunar infa rct ion ” as final stroke mechanism . Methods From 1990 to 1994 , 591 patients with cerebral infa rct ion , who were from northern Manhattan and over the age of 39 , were prospect ively examined . Data were collected on the admitting clinical syndrome ( lacunar or nonlacunar ) and brain imaging findings . Lacunar syndromes were categorized as pure motor hemiparesis ( PMH ) , pure sensory syndrome ( PSS ) , sensorimotor syndrome ( SMS ) , ataxic-hemiparesis ( A-H ) , and other lacunar syndromes . Brain imaging findings were classified as radiologic lacune or nonlacune . Positive predictive values , sensitivities , and specificities of lacunar syndromes for identifying radiologic lacunes were calculated . The final mechanism of infa rct ion was determined after review of all the diagnostic tests and compared among the lacunar groups . Results Lacunar syndromes occurred in 225 cases . PMH was the most common lacunar syndrome , accounting for 45 % , SMS 20 % , A-H 18 % , and PSS 7 % . Lacunar syndromes had an overall positive predictive value ( PPV ) of 87 % for detecting radiologic lacune : PSS loo% , A-H 95 % , SMS 87 % , and PMH 79 % . Among the 195 patients who presented with a lacunar syndrome and had this condition confirmed radiologically , 147 were classified as having a final diagnosis of lacunar mechanism of infa rct ion ( PPV = 75 % ) . Atherosclerosis accounted for 17 ( 9 % ) , cardioembolism 10 ( 5 % ) , cryptogenic 17 ( 9 % ) , and other unusual causes 4 ( 2 % ) . Conclusion While lacunar syndromes , especially PSS and A-H , are highly predictive of lacune , in about one in four patients presenting with lacunar syndromes confirmed radiologically the condition is associated with nonlacunar mechanisms of infa rct ion . Noninvasive neurovascular and cardiac evaluations are still warranted even among patients with lacunes To investigate the association between Chlamydia pneumoniae ( C. pneumoniae ) infection and atherosclerosis , we compared the effect of lipid-lowering drugs on carotid intima-media thickness ( IMT ) between patients who were positive and negative for C. pneumoniae antibodies . A total of 165 asymptomatic hypercholesterolemic patients were r and omized to probucol ( 500 mg per day , n = 82 ) or pravastatin ( 10 mg per day , n = 83 ) and followed for 2 years . The 2-year change of IMT in the common carotid artery was the primary endpoint , while mean IMT change and major cardiovascular events were secondary endpoints . C. pneumoniae antibodies ( IgA and IgG ) were measured by enzyme-linked immunosorbent assay . The 50 patients without C. pneumoniae antibodies showed significant reduction of IMT progression ( -19 % ) , while no significant change of IMT was noted in the 115 antibody-positive patients ( -6 % ) . Significant inverse associations were found between the reduction of IMT progression and the C. pneumoniae IgA- and IgG-antibody index ( P < 0.01 and 0.01 , respectively ) . No significant differences in the reduction of serum total-cholesterol and LDL-cholesterol were found between antibody-positive and -negative patients . There was no significant difference of efficacy between probucol and pravastatin . These observations suggest that C. pneumoniae infection reduces the effect of lipid-lowering therapy on carotid atherosclerosis and that this organism may play a role in the progression of atherosclerosis BACKGROUND AND PURPOSE Serological evidence of infection with Chlamydia pneumoniae has been associated with cardiovascular disease in multiple epidemiological studies . The data on its association with ischemic stroke are limited . We sought to determine whether chronic C pneumoniae infection is associated with ischemic stroke in a multi-ethnic population . METHODS The Northern Manh 
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Subgroup analysis by available studies suggested that C.pneumoniae may paly a role in atherosclerotic stroke , but be less significant in stroke of cardioembolism or other etiologies .
Conclusion Association between C.pneumoniae infection and CV disease depends on the analytical method adopted , which seems stronger with stroke due to large artery atherosclerosis .