A novel photoplethysmography technique to derive normalized arterial stiffness as a blood pressure independent measure in the finger vascular bed.

Stiffening of the small artery may be the earliest sign of arteriosclerosis. However, there is no adequate method for directly assessing small arterial stiffness. In this study, the finger arterial elasticity index (FEI) was defined as the parameter n which denotes the curvilinearity of an exponential model of pressure (P)-volume (V(a)) relationship (V(a) = a - b exp (-nP)). For the original estimation, the FEI was calculated from a compliance index from the finger photoplethysmogram whilst occluding the finger. A simple estimation of the FEI was devised by utilizing normalized pulse volume instead of the compliance index. Both estimations yielded close agreement with the exponential model in healthy young participants (study 1: n = 19). Since the FEI was dependent on finger mean blood pressure, normalized finger arterial stiffness index (FSI) was defined as standardized residual from their relationship: mean and standard deviation (SD) of the FSI were 50 ± 10 (study 2: n = 174). The mean coefficient of variation of the FSI for four measurements was 5.72% (study 3: n = 6). The mean and SD of the FSI in seven arteriosclerotic patients were 100.0 ± 13.5. In conclusion, the FEI and FSI by simple estimation are valid and useful for arteriosclerosis research.

Responses of ultra-weak chemiluminescence and secretory IgA in saliva to the induction of angry and depressive moods.

Oxidative damage to tissues and cells contributes to disease processes. We used ultra-weak chemiluminescence (uwCL) as an indicator of oxidative activity to examine the effects of psychological challenges on oxidative responses. We also examined the association of underlying psychological characteristics with oxidative and immune responses. Eighteen healthy men and women with a mean age of 24.1 were recruited. Anger and depressive symptoms were evaluated using the State-Trait Anger Expression Inventory and the Center for Epidemiological Studies Depression Scale, respectively. Following a baseline period, participants were required to complete two separate speech tasks where they were asked to recall life events that made them feel angry (AT) or depressed (DT). The tasks were separated by a 30-min recovery period and the order was randomized between participants using a counterbalanced design. Saliva was sampled and assayed for uwCL and secretory immunoglobulin A (sIgA). The level of uwCL was significantly increased in response to both tasks (p<.05), whereas sIgA concentrations decreased significantly in response to DT (p<.05). At 30 min after each task, uwCL values were positively related to anger-in (p<.005), anger expression (p<.05) and trait anger (p<.05) post-AT, and sIgA concentrations were positively related to anger-out (p<.05) post-AT and -DT, after controlling for covariates. The present study suggests that induction of angry and depressive moods can increase oxidative activity and transiently weaken immunity indicated by salivary sIgA concentrations. In addition, anger personality traits may modify these responses.

The effects of depressive symptoms on cardiovascular and catecholamine responses to the induction of depressive mood.

We examined the effects of depressive symptoms on cardiovascular and catecholamine responses to the induction of different mood states. Fifty-five healthy men and women (mean age 23.4 +/- 3 years) were recruited. Depressive symptoms were evaluated using the Center for Epidemiological Studies Depression Scale (CES-D) and participants were classified into high depressive (CES-D*16) or low depressive symptoms (CES-D < 16) groups. Following a baseline period, participants were required to complete two separate speech tasks where they were asked to recall life events that made them feel angry or depressed. The tasks were separated by a 30-min recovery period and the order was randomised between participants using a counterbalanced design. Cardiovascular function was monitored continuously using a Finometer device and saliva was collected for the assessment of 3-methoxy-phenylglycol (MHPG, the major metabolite of norephinephrine). Blood pressure (BP), heart rate, and total peripheral resistance (TPR) were significantly increased in response to both tasks (p = .001). Averaged over conditions, higher diastolic BP and higher MHPG levels were observed in high depressive symptoms participants. MHPG levels did not change in response to mood induction in the low depressive symptoms group. However, the high depression symptoms group showed significantly higher levels of MHPG during recovery from the depressed mood induction task and increased levels immediately after the anger induction task. These findings suggest depressive symptoms are associated with heightened central adrenergic activation during negative mood induction, but that the time course of responses is dependent on the type of emotion elicited.

Attention-Affect Check List: A self-report measure of acute mental stress.

Given a hint from Lang, Bradley, and Cutbert's (1997) defense cascade, two cognitive processes, instead of passive versus active behavioral coping, which seem to have differential effects on the provocation of vascular- versus cardiac-dominant reaction pattern during mental stress were advocated: attention (Attent) versus unpleasant affect (UnplAff). Based on this notion the Attention-Affect Check List (AACL) was developed as a self-report measure. In addition, items on uncontrollability (Uncontr) were prepared for the purpose of checking whether heightened Attent and UnplAff are accompanied by alterations in Uncontr. Two hundred and eighty-four students underwent two kinds of mental stress, which seemed to specifically heighten Attent and UnplAff. Four factors with four items each were extracted from the AACL item pool: concentrated and allocated Attent, UnplAff, and pleasant affect. Also, one factor with four items was extracted from the Uncontr item pool. For both the mental stresses, each scale, although very brief, had quite reasonable alpha reliability. Accountability of each scale for the total variance was reasonably high. Some problems are discussed in relation to the validity of AACL.

[Application of finger arterial compliance-blood pressure function for an evaluation of the sympathetically mediated vascular tone].

Normalized pulse volume (NPV, Sawada, Tanaka, & Yamakoshi, 2001) was calculated on a beat-to-beat basis by dividing the ac component by the dc component in near-infrared finger photoplethysmogram. Finger arterial compliance index (CI) was obtained by dividing NPV by the respective pulse pressure. Twelve female subjects underwent immersions of the contralateral hand in water at two different temperatures (44 degrees C, 22 degrees C). During the last 3 min of each of the 8-min resting and immersion conditions, CI was measured for the finger position at heart level, 15 cm, and 30 cm below the heart for 1 min each. Results indicated that a negatively linear regression could be applied to the beat-to-beat data on log CI and mean blood pressure (MBP) over the three finger position (whole regression). CI calculated at 90 mmHg (CI 90) was arbitraily chosen as a reference point for comparing compliance among conditions. CI 90 decreased significantly during the 22 degrees C condition. In conclusion, CI seemed more valid as an index of the finger arterial vascular tone through the removal of MBP influence.

Examination of normalized pulse volume-blood volume relationship: toward a more valid estimation of the finger sympathetic tone.

The pulsatile ac component (DeltaI) superimposed on the transmitted dc components (I: tissue plus blood) are obtained from a near-infrared finger photoplethysmogram using a wavelength of 810 nm. Only the dc component is given in an ischaemic circulatory state (I(t): tissue only). Based on Lambert-Beer's law, normalized pulse volume (NPV; =DeltaI/I) and blood volume [BV; =ln(I(t)/I)] have recently been advocated as quantitative measures. In this study, the NPV-BV relationship was examined using the finger occlusion method during rest and mental arithmetic in 16 female undergraduates. Finger vascular tone during stress was evaluated by the distance of the linear and parallel NPV-BV regression lines (D(NB)) between rest and stress conditions. A reference standard was provided by the linear regression lines of compliance index (CI=NPV/pulse pressure) and BV to the transmural pressure. The estimates at 40 mmHg of transmural pressure, as an arbitrarily chosen reference point, were calculated (CI40 and BV40). D(NB) correlated well with them (r=0.81 and 0.94, respectively). The multiple regression with mean blood pressure indicated that the combination of D(NB) and the reactivities in heart period could explain approximately 50% of valiance in pressor response. In conclusion, D(NB) is easily obtainable from the NPV-BV function and seems to be more specific and valid than NPV as an index of finger sympathetic tone, since it adjusts the mechanical effect of arterial distending pressure.

Finger arterial compliance as determined by transmission of light during mental stress and reactive hyperaemia.

A near-infrared finger photoplethysmogram adopting a wavelength of 810 nm provides data pertaining to the pulsatile a.c. component of finger blood flow (delta I) superimposed on the transmitted d.c. components in a normal ( I: tissue plus blood) and an ischaemic circulatory state ( I(t): tissue only). Simultaneous recording of finger blood pressure provides data pertaining to the distending pulse (PP) and mean blood pressure. Based on the Lambert-Beer law, indices of the arterial compliance (CI=delta I/ I/PP) and distensibility [DI=delta I/ I/ln( I(t)/ I)/PP] are advocated for assessing finger vasculature. The functional relationships between transmural pressure and CI and DI were examined using finger occlusion while performing an arithmetic test (i.e. a mental stress) in 16 females, and during reactive hyperaemia in 5. Gradual occlusion of the finger was conducted at 20-s intervals and the beat-by-beat transmural pressure was determined by calculating mean blood pressure minus the occluding cuff pressure. Logarithmically transformed CI and DI data were linearly associated with the transmural pressure; thus, the estimates obtained at a transmural pressure of 40 mmHg were chosen as an arbitrary reference point (CI40 and DI40). The results indicated that CI40 and DI40 were reduced while performing an arithmetic test, and increased during reactive hyperaemia. Responses were larger for CI40 than for DI40. In conclusion, noninvasive finger occlusion allowed the measurement of the compliance/distending pressure relationship, and CI40 could be utilised to evaluate changes in finger vascular tone.