Cholesterol Concentrations and Cardiovascular Reactivity to Stress in African American College Volunteers

Cholesterol levels and cardiovascular responses to emotionally arousing stimuli were examined in 60 healthy African American males and females. Cardiac output, stroke volume, contractile force, heart rate, and blood pressure were measured as the participants viewed two racially noxious scenes on videotape. Total serum cholesterol, high-density lipoproteins (HDL), low-density lipoproteins (LDL), and triglycerides were measured within 2 weeks of viewing the scenes. Multiple regression analysis showed that LDL and HDL were significant predictors of blood pressure responses. A correlation analysis revealed that total serum cholesterol and LDL were positively correlated with stroke volume, contractile force, and blood pressure reactivity. A possible relationship among stress, -adrenergic activity, and nonmetabolized free fatty acids is discussed. These findings suggest that cardiovascular reactivity to stress may be a new risk factor for heart and vascular diseases.     

The Effects of Cognitive and Physical Stress on Cardiovascular Reactivity Among Smokers and Oral Contraceptive Users

Blood pressure and heart rate responses to cognitive (mental arithmetic) and physical (cold pressor) stress were monitored in four groups of women: 1) smokers/non oral contraceptive (OC) users, 2) non-smokers/OC users, 3) smokers/OC users, and 4) non-smokers/non-OC users (control). All subjects were reactive to both types of stress. The results suggest that oral contraceptive use among smokers may enhance systolic blood pressure reactivity to cognitive stress when compared to smokers/non-OC users. Also, OC use among women with a parental history of heart disease was marginally associated with elevated systolic and diastolic blood pressure responses to the cold pressor test. These findings suggest that oral contraceptive use may interact with smoking and parental history of heart disease and warrant further investigation.     

Memory B Cell and Other Immune Responses in Children Receiving Two Doses of an Oral Killed Cholera Vaccine Compared to Responses following Natural Cholera Infection in Bangladesh

Current oral cholera vaccines induce lower protective efficacy and shorter duration of protection against cholera than wild-type infection provides, and this difference is most pronounced in young children. Despite this, there are limited data comparing immune responses in children following wild-type disease versus vaccination, especially with regard to memory responses associated with long-term immunity. Here, we report a comparison of immune responses in young children (2 to 5 years of age; n = 20) and older children (6 to 17 years of age; n = 20) given two doses of an oral killed cholera vaccine containing recombinant cholera toxin B subunit (CtxB) 14 days apart and compare these responses to those induced in similarly aged children recovering from infection with Vibrio cholerae O1 Ogawa in Bangladesh. We found that the two vaccine groups had comparable vibriocidal and lipopolysaccharide (LPS)-specific plasma antibody responses. Vaccinees developed lower levels of IgG memory B cell (MBC) responses against CtxB but no significant MBC responses against LPS. In contrast, children recovering from natural cholera infection developed prominent LPS IgG and IgA MBC responses, as well as CtxB IgG MBC responses. Plasma LPS IgG, IgA, and IgM responses, as well as vibriocidal responses, were also significantly higher in children following disease than after vaccination. Our findings suggest that acute and memory immune responses following oral cholera vaccination in children are significantly lower than those observed following wild-type disease, especially responses targeting LPS. These findings may explain, in part, the lower efficacy of oral cholera vaccination in children.     

Premenopausal and Postmenopausal Women Differ in their Cardiovascular and Neuroendocrine Responses to Behavioral Stressors

Middle-aged (45-51 years) women performed four tasks while their heart rate, blood pressure, and plasma catecholamines were measured. The tasks were serial subtraction, mirror image tracing, speech, and postural tilt. The speech task was considered to be particularly relevant to women because of its emphasis on social skills. Fifteen premenopausal women reported menstruating regularly and were tested in the early follicular phase. Sixteen postmenopausal women reported not menstruating for at least 12 months and their hormonal status was verified by serum levels of follicle-stimulating hormone. Results showed that postmenopausal women exhibited greater increases from baseline in heart rate during all tasks, relative to premenopausal women, with a particularly pronounced increase during the speech task. Postmenopausal women exhibited greater increases from baseline in systolic blood pressure and epinephrine, relative to premenopausal women, during the speech task only. Explanations for the stressor-specific effect of menopausal status were discussed. The results suggest that reproductive hormones may interact with stressor characteristics to determine middle-aged women's physiological responses to stress.     

Histological Changes in Male Accessory Reproductive Organs in Rats Exposed to Cigarette Smoke and the Protective Effect of Honey Supplementation

The effect of cigarette smoke (CS) on histology of male accessory reproductive organs and the possible protective effect of honey supplementation in rats were investigated in this study. Rats received distilled water, honey, CS exposure or honey plus CS exposure. Honey (1.2 g/kg body weight/day) was administered by gavage and CS exposure (3 times per day) was done in a chamber for 13 weeks. CS exposure significantly increased relative weight of epididymis and ventral prostate. There were also significantly increased number of clear cells and epithelial height of cauda epididymis as well as severe interstitial oedema and decreased epithelial height of prostate gland. However, with the supplementation of honey, these histological changes were significantly reversed suggesting the protective effect of honey against the toxic effect of CS on male accessory reproductive organs in rats.     

Cardiovascular Responses to Mental Arithmetic and Handgrip During Different Conditions of Postural Change

Twenty healthy male subjects, aged 18–29 yrs, were studied during three sequences of four different postural trials-sitting, sitting to standing, standing, and standing to sitting. The first sequence was a baseline, without other stimulation. In the remaining two, subjects performed a mental arithmetic task and an isometric handgrip task during each trial (counterbalanced). Systolic blood pressure, diastolic blood pressure, heart rate, and skin conductance were recorded during the trials. The physiological responses to the two tasks were shown to vary as a function of the specific postural trial. Systolic and diastolic blood pressure were generally more sensitive to these effects than heart rate or skin conductance. The two tasks facilitated increases in blood pressure during the sitting to standing trials, especially during the standing phase. The increases in blood pressure were comparable to those reported previously for voluntary control and biofeedback procedures. Mental and physical strategies are effective in increasing blood pressure during postural change and may be useful in the management of orthostatic hypotension.     

Apolipoprotein E Phenotypes and Cardiovascular Responses to Experimentally Induced Mental Stress in Adolescent Boys

We investigated the relationship between apolipoprotein E (apoE) polymorphism and cardiovascular responses to experimentally induced mental stress. Mental stress was induced in 28 healthy 16-year-old boys with a series of stressors (e.g., mental arithmetic, Stroop Color-Word Interference Test). Heart rate (HR), finger blood volume, and skin conductance level were recorded continuously during the task performance. We found that boys with apoE3/2 or apoE3/3 showed marginally significantly greater HR reactivity and significantly greater task levels of HR and HR variability (HRV) during the mental stress than subjects with apoE4/2, apoE4/3, or apoE4/4. In addition, E4/2, E4/3, and E4/4 subjects manifested a distinct stress-related decrease in HRV relative to baseline values while E3/2 and E3/3 subjects showed a slight increase. The results suggests that apoE polymorphism is associated with cardiovascular responsivity to mental stress in adolescent boys.     

Sex Differences in Lipid, Lipoprotein, Cardiovascular, and Neuroendocrine Responses to Acute Stress

This study had two objectives: (a) to examine whether or not lipids and lipoproteins change in response to acute behavioral stress in young adults; and (b) to test the extent of sex differences in the magnitude of the lipid, lipoprotein, neuroendocrine, and cardiovascular changes during stress. Nineteen women and 22 men participated in a serial subtraction task, a videotaped speech task, and a self-evaluation task. The cholesterol portions of low density and high density lipoproteins, triglycerides, free fatty acids, epinephrine, norepinephrine, heart rate, and blood pressure were examined at rest and during each stressor. Repeated measures analyses of variance indicated that stress-related levels of low density and high density lipoprotein-cholesterol, triglycerides, free fatty acids, norepinephrine, heart rate, and blood pressure were elevated, relative to baseline, and that these responses were partially task or order dependent. Subsequent analyses of sex differences showed that males had larger low density lipoprotein-cholesterol and blood pressure increases during all tasks, relative to those of females, and females had larger heart rate responses to the speech task, relative to those of males. There were no sex differences in plasma catecholamine adjustments. These data demonstrate that the cholesterol fractions of high and low density lipoproteins increase during acute psychological stress, and are the first to systematically examine male/female differences in those stress responses.     

Sleep Stage Physiology, Mood, and Vigilance Responses to Total Sleep Deprivation in Healthy 80-Year-Olds and 20-Year-Olds

Little is known about sleep and the effects of total sleep loss in the 'old old' (i.e., 80-year-olds). We investigated sleep, mood, and performance responses to acute sleep deprivation in healthy 80-year-olds (n = 10) and 20-year-olds (n = 14). The protocol consisted of three nights of baseline sleep, one night of total sleep deprivation, and two nights of recovery sleep. Mood and vigilance were tested using visual analog scales and a Mackworth clock procedure in the morning and evening of each study day. Daytime sleepiness was measured by five naps on the days following the third and sixth nights. Old subjects had lower sleep efficiency and less delta sleep than young subjects. However, sleep continuity and delta sleep were enhanced in both groups on the first recovery night, indicating that sleep changes in old subjects are at least partially reversible by this procedure. Surprisingly, young subjects had shorter daytime sleep latencies than the old, suggesting a greater unmet sleep need in the former group. Mood and performance were disturbed by sleep loss in both groups, but to a greater extent among the young. This suggests that acute total sleep loss is a more disruptive procedure for the young than for the old.     

Serum Lipids,Neuroendocrine, and Cardiovascular Responses to Stress in Men and Women with Mild Hypertension

Abstract

In this study, we examined the relation between serum lipid levels, gender, and cardiovascular and neuroendocrine stress reactivity in patients with mild hypertension. Ninety-nine individuals (62 men, 37 women) with mild hypertension performed four mental stress tasks: mental arithmetic, public speaking, cold stress, and a computer videogame. Cardiovascular reactivity scores were computed by subtracting the minimum resting blood pressure (BP) and heart rate (HR) values from the maximum values obtained during each task. Neuroendocrine reactivity was calculated as the change from epinephrine and norepinephrine values from mean rest to mean task. High and low reactors were identified on the basis of median splits of reactivity scores, averaged across all four stressors. High systolic blood pressure reactors had higher levels of total (TC), low-density lipoprotein cholesterol (LDL-C), and apo-B than did low reactors. High diastolic blood pressure reactors had lower levels of high-density lipoprotein cholesterol (HDL-C) and higher levels of LDL-C and apo-B than did low reactors. High HR reactors had higher apo-AI:apo-AII ratios than low reactors. Lipid levels were not different for high and low epinephrine and norepinephrine reactors. Although women were noted to have more favorable lipid profiles than men, both male and female hypertensive patients who were high reactors had less favorable lipid profiles than low reactors.     

Parental History of Hypertension and Myocardial Infarction Predicts Cardiovascular Responses to Behavioral Stressors in Middle-aged Men and Women

The present study had two objectives: to examine the influence of parental history of hypertension on cardiovascular responses during behavioral stress in middle-aged men and women; and to study the impact of parental history of myocardial infarction on stress responses. Participants were separated into four groups: no parental history of cardiovascular disease; parental history of hypertension only; parental history of myocardial infarction only; or parental history of both hypertension and myocardial infarction. Heart rate and blood pressure were monitored at rest and during serial subtraction, mirror image tracing, and isometric handgrip. Analyses of residualized difference scores showed that like younger, male offspring of hypertensives, middle-aged men and women with a parental history of hypertension exhibited exaggerated diastolic blood pressure responses during all stressors. Men with a parental history of myocardial infarction, with or without a parental history of hypertension, exhibited exaggerated systolic blood pressure responses during all stressors. These data are the first to show that family history of hypertension influences middle-aged men's and women's stress responses, and that family history of myocardial infarction influences men's stress responses. Results suggest the importance of parental history of cardiovascular diseases in understanding acute psychophysiological responses of middle-aged adults.     

Differences in Specific Antibody Responses of Human Tonsillar Cells to an Oral and a Parenteral Antigen

Tonsillar lymphocytes stimulated in vitro with either β-lactoglobulin or with tetanus toxoid were shown to produce specific antibodies by a direct plaque assay and by radioimmuno-precipitation of the culture supernatants. There was a sixfold increase in the number of IgA-secreting cells in response to β-lactoglobulin; no such effect was seen in response to tetanus toxoid, where a fivefold rise in IgG-secreting cells occurred. These differences in antibody response are probably due to the route of initial antigen presentation. Those antigens priming the mucosa-associated lymphoid system stimulate mainly IgA-producing cells, in contrast to parenteral antigens, which elicit a predominantly IgM and IgG response.     

Cardiovascular Responses to Emotional Stress (Quiz Interview) in Post-Myocardial Infarction Patients and Matched Control Subjects

Abstract

In this investigation, 30 male post-myocardial infarction patients and 30 male control subjects matched according to age and occupation were given a 12-minute tape-recorded stress quiz described by Schiffer et al.' Cardiovascular responses (electrocardiogram, heart rate, systolic, blood pressure, and diastolic blood pressure) to emotional stimuli were monitored in a laboratory setting at rest before the quiz and at two-minute intervals during the quiz. Heart rate and blood pressure values were significantly higher during the quiz than at rest for both patient and control groups. There was a significantly higher response for diastolic pressure and a significantly lower response for heart rate in the patient group compared with the control group. In the analysis for occupational status in the entire population, systolic pressure was significantly higher for the executives than for non-executives. Subgroup analyses of patients with angina, hypertension and/or ECG changes (N=12) revealed a significantly higher diastolic pressure response than found in either the patients without these symptoms (N=18) or in the controls (N=30). In comparison to exercise test results, the emotional stress test (quiz) elicited somewhat more PVC's but less ST segment depression. These results support previous reports suggesting that emotional stress testing may be a valid tool in the diagnosis of coronary heart disease and in determining the physiological mechanisms which underlie the association between emotional stress and coronary heart disease.     

Cardiovascular Responses to the Combination of Caffeine and Mental Arithmetic, Cold Pressor, and Static Exercise Stressors

The present study examined cardiovascular responses to the combination of caffeine (250mg) and mental arithmetic, cold pressor, and static exercise stressors in 48 healthy males. Subjects were tested in a within-subject, placebo-controlled, double-blind design. Repeated measurements of heart rate, finger temperature, respiratory sinus arrhythmia, forearm blood flow, and blood pressure were obtained during a pre-drug resting baseline, a post-drug resting baseline, the three stressor tasks, and a recovery baseline. The primary analyses were 2(Drug) x 5(Period) x 6(Stress Order) MANCOVAs using pre-drug baseline values as covariates. Significant period main effects were observed for all measures. Significant drug main effects were observed for blood pressure, finger temperature, respiratory sinus arrhythmia, and forearm blood flow. The significant changes in blood pressure and finger temperature produced by caffeine combined in an additive fashion with the effects produced by the stressors. Significantly greater increases in forearm blood flow and heart rate during mental arithmetic on the caffeine day suggested a potentiation of sympathetic, beta-adrenergic activity. Questionnaires administered during baseline periods to assess psychological responses to stress and caffeine revealed a potentiation of anxiety and anger responses to stress on the caffeine day.     

Cardiovascular Responses to Stress: I. Measures of Myocardial Response and Relationship to High Resting Systolic Pressure and Parental Hypertension

A comparison of pre-ejection period (PEP), heart rate (HR), and systolic (SBP) and diastolk (DBP) blood pressure responses to the cold pressor test and a pseudo-shock avoidance reaction time task was performed in 183 young men. These tasks differ in the extent to which they evoke enhanced myocardial and vascular adrenergic activity. Decreases in PEP were more pronounced during the reaction time task, while DBP increased more during the cold pressor test. MR and SBP responses did not differentiate the two tasks. PEP decreases occurred in the absence of any apparent increase in cardiac preload or decrease in afterload. Parental hypertension as determined by physician reports was associated with higher SBP across all conditions. A subgroup of individuals (15%) showed SBP levels >140 mm Hg when typical clinical stethoscopic determinations were made, but less than half as many showed such elevations during a more extended resting baseline using remotely operated devices. High stethoscopic SBP was associated with greater cardiovascular responses to the stressors, while high SBP during the extended baseline was not.     

The Effect of Exposure of Guinea Pig to Cigarette Smoke and their Sensitization in Tracheal Responsiveness to Histamine and Histamine Receptor (H(1)) Blockade by Chlorpheniramine.

Airway responsiveness to histamine and histamine H(1) receptor blockade by chlorpheniramine (CR-1) on guinea pig trachea were examined. Chronic obstructive pulmonary disease (COPD) and asthma were induced in guinea pigs by exposing them to cigarette smoke for 3 months and by sensitization with injection and inhalation of ovalbumin (OA). The responses of tracheal chains of COPD (n=8), COPD+asthma (n=6) and control animals (n=8) to histamine (EC(50) H) and (CR-1) were measured. The in vitro histamine responses of COPD and COPD+asthmatic guinea pigs in tracheal chains were significantly higher than those of control animals (p<0.001 and p<0.01, respectively). The CR-1 blockade was also significantly greater in trachea of COPD and COPD+asthma compared to that of controls (p<0.01 and p<0.05, respectively). There were significant correlations between EC(50) H and (CR-1) (r=-0.542, p<0.01). The hematocrit in COPD and COPD+asthma groups was also significantly higher than in controls (p<0.001 for both groups). The contractility of tracheal chains to histamine in COPD+asthma animals was significantly greater than those of control and COPD groups (p<0.05 for both cases). The differences in contractility between COPD and COPD+asthmatic groups, however, suggests different basic mechanisms for AHR in COPD and asthma.     

Effect of Harassment and Competition Upon Cardiovascular and Plasma Catecholamine Responses in Type A and Type B Individuals

Two experiments examined the relationship between Type A behavior and cardiovascular and plasma catecholamine responses to experimental competition and harassment. Experiment I showed that, in 44 male adults, the presence of a hostile opponent caused no significant differences in the responses of Type B's. In A's, by contrast, hostility elicited greater increases in systolic blood pressure, heart rate and plasma epinephrine during competition. Behavior pattern A appears selectively predisposed to enhanced reaction to hostile interactions, but competition alone does not distinguish between individuals with A and B behavior patterns. Experiment II, with 20 cases, was carried out to determine whether or not the absence of A-B differences in the presence of a nonhostile competitor could be explained by Type B's reactivity to the challenge of competition alone. The results were consistent with this interpretation. A's showed greater blood pressure and plasma epinephrine evaluations than B's when both types were confronted by the challenge of task performance. Consideration was given to the role of sympathetic activation in mediating the tendency of Type A individuals to develop coronary heart disease.