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Paper text:
hypertension is a major cardiovascular risk factor , and cardiovascular disease is a leading cause of premature morbidity and mortality in china .
the joint national committee 7 ( jnc 7 ) report describes prehypertension as an independent category of blood pressure . with the exception of people who take antihypertensive drugs ,
people with systolic blood pressure ( sbp ) between 120 and 139 mmhg or diastolic blood pressure ( dbp ) between 80 and 89 mmhg are deemed to have prehypertension . compared to people with normal blood pressure ,
these people require lifestyle modifications to decrease the risk of progression to hypertension and to prevent cardiovascular disease . in the clinical setting ,
elevation of serum factors such as low - density lipoprotein cholesterol ( ldl ) were believed to be predictive factors for atherosclerotic cardiovascular disease and mortality . besides these traditional risk factors , high - sensitivity c - reactive protein ( hs - crp ) ,
a marker of low - grade inflammation , has been used as a predictor of cardiovascular mortality and morbidity in healthy people .
elevation of hs - crp may suggest acute involvement of inflammation in the development of hypertension and always occurs before blood pressure elevation . at the same time
, it was demonstrated that elevated serum sialic acid ( sa ) is associated with increased cardiovascular mortality [ 911 ] and could be associated with prehypertension in indians .
the purpose of this study was to investigate the correlations of sa and hs - crp in chinese prehypertensive patients .
we detected and analyzed potential cardiovascular risk factors such as dyslipidemia , elevated hs - crp , and sa to explore the possible relationship between these 2 factors in volunteers with hypertension , prehypertension , and normal blood pressure .
the study protocol received ethics approval from the china - japan friendship hospital regional ethics committee . written informed consent was obtained from each participant in accordance with the declaration of helsinki .
we enrolled 181 volunteers deemed healthy based on physical examination at the china - japan friendship hospital in july 2011 .
we excluded volunteers with the following conditions : secondary hypertension , coronary heart disease , myocardial infarction , heart failure , cerebrovascular disease , diabetes , gout , incomplete liver and kidney function , recent infection , pregnancy , habitual drinking , habitual smoking , blood system diseases , and other endocrine diseases .
based on the 2010 china hypertension prevention and control guidelines , the volunteers were divided into 3 groups : 50 in the normal blood pressure group ( control ; sbp < 120 mmhg , dbp < 80 mmhg ) , 61 in the prehypertension group ( sbp 120~139 mmhg and/or dbp 80~89 mmhg ) , and 70 in the hypertension group ( sbp 140 mmhg and/or dbp 90 mmhg ) .
blood pressure was determined using a standard mercury sphygmomanometer ; it was measured thrice and the average value was recorded as the volunteer s blood pressure . the body mass index ( bmi )
volunteers were required to eat lightly for 3 days before measurements were obtained , with a compulsory water - only fast 12 h before measurement ; 5 ml venous blood was collected from the volunteers in resting conditions .
the plasma was used for estimating the lipid profile , apolipoprotein b , serum hs - crp , and sa .
shanghai shen suoyou fu medical diagnostic products provided the reagents for testing serum total cholesterol ( tc ) , triglyceride ( tg ) , high - density lipoprotein cholesterol ( hdl ) , ldl , and fasting glucose ( fbg ) .
the landau british company provided the reagents for hs - crp and the serum sa detection kit was from wenzhou east ou jin ma biotechnology .
variance analysis was used for comparison among groups and t - test was used for comparison between groups . the relationship between serum sa and hs - crp with prehypertension
figure 1 depicts the general characteristics and clinical profiles of the hypertensive , prehypertensive , and control volunteers . there was no significant difference in sex and age among these 3 groups .
there was a significant gradient increase in sbp , dbp , bmi , sa , and hs - crp levels in all 3 groups .
the levels of sa , hs - crp , and bmi in prehypertensive patients were higher than in healthy controls ( p=0.015,0.006 , and 0.004 , respectively ; figure 1a , 1b , 1e ) and lower than in hypertensive groups ( p=0.02 , 0.008 , 0.005 , respectively ; figure 1a , 1b , 1e ) .
the level of hdl in prehypertensive patients was lower than in healthy controls and higher than in hypertensive groups ( p=0.007 and 0.004 , respectively ; figure 1d).compared with the controls , tc , ldl , and fbg levels were significantly increased in hypertensive volunteers ( p=0.003 , 0.008 , 0.002 ; respectively , figure 1c , 1d , 1f ) .
there were no significant differences in tc , ldl , and fbg between healthy controls and prehypertensive patients or between prehypertensive and hypertensive patient groups .
we used multiple linear stepwise regression to evaluate the relationship between serum sa and hs - crp with blood pressure in the 3 groups . using sbp and dbp as dependent variables and tc , hdl , ldl , tg , fbg , bmi , sa , and hs - crp as independent variables , we found that fbg , bmi , sa , and hs - crp were independently associated with sbp ( p=0.02 , 0.001 , 0.01 , 0.002 , respectively ; table 1 ) , and ldl , bmi , sa , and hs - crp were independently associated with dbp ( p=0.03 , 0.03 , 0.04 , 0.001 , respectively ; table 2 ) .
there is a positive correlation between hypertension and cardiovascular disease , and hypertension is becoming a serious threat to human health . the jnc 7 report describes prehypertension as an independent category of blood pressure .
.   demonstrated that prehypertension precedes the development of hypertension in 90% of people and that it can increase the risk of cardiovascular disease [ 1317 ] .
identifying the risk factors for early hypertension would be of great significance in preventing cardiovascular disease .
crp , which is synthesized by the liver , can respond to factors released by macrophages and fat cells . as an acute - phase protein
active in the response to inflammation , crp also can predict cardiovascular mortality and morbidity in healthy people . in this study ,
there was a positive correlation between serum hs - crp level and sbp and dbp .
the following facts may be associated with the relationship between serum crp and blood pressure : ( 1 ) crp can damage vascular endothelial cells , reduce the release of nitric oxide and prostaglandin , and weaken the vasodilatation function ; ( 2 ) elevation of blood pressure can damage vascular endothelial cells and activate the inflammation response , followed by elevated crp ; and ( 3 ) elevated crp can increase endothelin release , contract blood vessels , and promote vascular smooth - muscle cell proliferation and migration , and the development of atherosclerosis .
overall , crp is an important inflammatory factor , being significantly correlated with blood pressure in prehypertensive and hypertensive volunteers .
several studies have demonstrated an association between serum sa and cardiovascular mortality in the general population . as a potential risk factor
, sa can be an acute - phase response marker in cardiovascular disease . in this study
, there was a significant gradient increase in the sa levels of prehypertensive and hypertensive volunteers compared with that of the controls ( p<0.05 ) .
this suggests that the blood sa levels in these volunteers increased before they developed high blood pressure . in other words ,
three mechanisms may be involved in the influence of blood sa levels on blood pressure .
firstly , sa can promote atherosclerosis development by the inflammatory response , interfere with iron metabolism , and promote platelet thrombus formation mechanisms .
sa is the main source of vascular endothelial cell surface negative charge ; it can influence the vascular endothelial cell function for promoting the development of hypertension .
thirdly , sa can also affect ldl metabolism , inducing vascular smooth muscle damage , and the damaged muscle can promote the development of hypertension .
similar to crp , sa is associated with and is a predictor of cardiovascular disease and type 2 diabetes .
compared with crp , sa may be a more stable inflammatory marker because it can reflect the overall level of acute - phase reaction , whereas crp only represents the acute - phase reaction when it is released from the liver .
there were significant differences in tc , ldl , and fbg levels between the prehypertension and control groups .
the increased tc and ldl levels suggested that the prehypertensive volunteers also had blood lipid and blood glucose disorders .
blood lipids , blood glucose , and blood pressure can be involved in synergistic mutual promotion .
in conclusion , acute - phase markers such as sa and hs - crp were significantly increased in prehypertensive and hypertensive volunteers .
the increased serum sa and hs - crp levels were independently associated with sbp and dbp , respectively .
higher levels of these 2 factors may suggest a greater risk for future high blood pressure .
clinically , comprehensive hypertension risk can be evaluated by detecting blood , salivary , and serum crp in prehypertensive patients , and pharmacological tools can be developed to ameliorate the development of hypertension in this highly susceptible section of the population .
backgroundthe aim of our study was to evaluate the serum concentration of sialic acid ( sa ) and high - sensitivity c - reactive protein ( hs - crp ) in prehypertensive patients and the possible correlations between these 2 factors with blood pressure in such patients.material/methodswe studied 61 prehypertensive patients , 70 hypertensive patients , and 50 controls with normal blood pressure . 
 lipid profile , hs - crp , sa , and body mass index ( bmi ) were estimated in all groups . 
 associations between sa and hs - crp and blood pressure were analyzed using multiple linear regressions.resultssa and hs - crp levels were higher in the prehypertension group than that in the control group and were lower than that in the hypertension group . 
 multiple linear regression demonstrated that fasting glucose , bmi , sa , and hs - crp correlated with systolic blood pressure and that low - density lipoprotein , bmi , sa , and hs - crp correlated independently with diastolic pressure ( p<0.05).conclusionsour findings suggest that in prehypertension , there is an association between serum sa and hs - crp levels and blood pressure .