Biomedical subjects

Kathleen C Light

Publications and source records attributed to Kathleen C Light.

30 records · Page 2Linked to original sources

PubMed2004

Postprandial ghrelin is elevated in black compared with white women.

Ghrelin, a gut-brain peptide that signals hunger, is normally suppressed after meals. Subnormal suppression of postprandial ghrelin, previously noted in obese, insulin-resistant individuals, may contribute to increased food intake. Given the ethnic disparities in obesity and obesity-related cardiovascular morbidity in the United States, the present study compared a single postprandial ghrelin measure in 43 women (22 white, 21 black). Each completed a rigorously controlled 4-d dietary intervention designed to maintain weight and constant daily sodium and potassium intake (220 mEq Na, 40 mEq K). Two hours after consuming a test meal of identical content, blood samples were drawn to assess postprandial ghrelin, leptin, and norepinephrine; resting cardiovascular function was measured; and a 24-h urinary cortisol sample was obtained. Independent of body mass index, postprandial ghrelin was significantly higher in black vs. white women, and higher ghrelin was associated with higher cortisol in blacks, who failed to show the expected inverse relation between ghrelin and central obesity seen in whites. Higher ghrelin was correlated with higher blood pressure but lower norepinephrine in obese women. These findings suggest subnormal postprandial ghrelin suppression (or faster ghrelin rebound) in black women, especially the obese, that might play a role in their increased prevalence of obesity and cardiovascular disorders.

Adult↗

PubMed2003

Warm partner contact is related to lower cardiovascular reactivity.

The authors investigated the relationship between brief warm social and physical contact among cohabitating couples and blood pressure (BP) reactivity to stress in a sample of healthy adults (66 African American, 117 Caucasian; 74 women, 109 men). Prior to stress, the warm contact group underwent a 10-minute period of handholding while viewing a romantic video. Followed by a 20-second hug with their partner, while the no contact group rested quietly for 10 minutes and 20 seconds. In response to a public speaking task, individuals receiving prestress partner contact demonstrated lower systolic BP diastolic BP, and heart rate increases compared with the no contact group. The effects of warm contact were comparable for men and women and were greater for African Americans compared with Caucasians. These findings suggest that affectionate relationships with a supportive partner may contribute to lower reactivity to stressful life events and may partially mediate the benefit of marital support on better cardiovascular health.

Adult↗

PubMed2003

Sympathoadrenergic mechanisms in reduced hemodynamic stress responses after exercise.

PURPOSE: This study examines the acute effects of moderate aerobic exercise on 1) hemodynamic and sympathetic activity during behavioral stress and 2) beta-adrenergic receptor responsivity in a biracial sample of 24 sedentary adults. METHODS: Before and after exercise, blood pressure (BP), impedance-derived cardiovascular measures, and plasma norepinephrine (NE) and epinephrine (EPI) were assessed during mental arithmetic and active speech tasks, and beta-adrenergic receptor responsivity was assessed using a standard isoproterenol challenge procedure. RESULTS: After exercise, BP, NE, and EPI responses to stress were reduced (0.0001 < P < 0.08), preejection period (PEP) was elongated (P < 0.0001), and beta(1)- and beta(2)-receptor responsivity (P < 0.02) was enhanced. Approximately 65% of the prepost exercise mean arterial pressure response difference could be accounted for by changes in sympathetic factors, with change in NE and PEP being the single best predictors. CONCLUSIONS: Reduced BP responses to stress after acute exercise are strongly linked to a decrease in sympathetic drive, as evidenced by reduced NE responses and elongation of the PEP. Coincident with this overall dampening of the hemodynamic response to stress, increases in cardiac and vascular beta-adrenergic receptor responsivity occur. These findings may have important implications for future translational studies that seek to articulate the mechanisms through which regular aerobic exercise reduces the risks of hypertensive and coronary heart disease.

Adult↗

PubMed2002

Changes in hemodynamics and left ventricular structure after menopause.

To evaluate the cardiovascular changes associated with menopause, we studied hemodynamics at rest, ambulatory blood pressure, and left ventricular structure in a biracial cohort of pre- and postmenopausal women of similar age, race, weight, and blood pressure. Despite similar levels of blood pressure, postmenopausal women had a higher indexed peripheral resistance (2,722 +/- 757 vs 2,262 +/- 661 dynes.s.m(2)/cm(5), p <0.01) and a lower cardiac index (2.64 +/- 0.73 vs 3.10 +/- 0.71 L/min.m(2), p <0.01) than premenopausal women. Postmenopausal women also had less nocturnal decreases in both systolic (15 +/- 8 vs 19 +/- 8 mm Hg, p <0.01) and diastolic (12 +/- 6 vs 15 +/- 6 mm Hg, p = 0.05) pressures during ambulatory monitoring and higher levels of hematocrit (40 +/- 2% vs 38 +/- 3%, p <0.01). In association with this greater hemodynamic load, postmenopausal women had evidence of early concentric left ventricular remodeling, manifested by a greater relative wall thickness (0.38 +/- 0.06 vs 0.35 +/- 0.06, p <0.01) than that observed in premenopausal women. Differences between pre- and postmenopausal women in hemodynamics, diurnal blood pressure variation, and left ventricular structure were observed in white and African-American subjects. These results suggest that menopause is associated with hemodynamic changes and left ventricular remodeling, which may contribute to the enhanced cardiovascular risk observed in postmenopausal women.

Black or African American↗

PubMed2002

Group differences in pain modulation: pain-free women compared to pain-free men and to women with TMD.

Previously reported differences in sensitivity to experimental pain stimuli between the sexes, as well as between temporomandibular disorder (TMD) patients and healthy control subjects, may be attributable in part to group differences in two pain modulatory mechanisms: the baroreceptor reflex arc and the endogenous opioid system. Twenty-two pain-free (PF) men, 20 PF women and 20 women with TMD underwent two testing sessions in which heat pain and ischemic arm pain threshold and tolerance were measured during both sessions, but followed relaxation during one session and laboratory stress tasks during the other. Blood pressure (BP) and plasma -endorphin (E) concentration were measured during a baseline rest and during the stress or relaxation periods. PF men's threshold and tolerance for heat pain, but not for ischemic pain, exceeded that of PF women's during both sessions. PF women and TMD women did not differ in sensitivity to either pain modality; however, significantly lower ischemic pain threshold (IPTh) was linked to oral contraceptive use in PF women but not TMD patients. In the men alone, higher baseline systolic BP (SBP) was correlated with higher heat pain threshold on both days and heat pain tolerance on the stress day. Conversely, in TMD women, higher baseline SBP was correlated with lower ischemic pain tolerance (IPTol) on both days; BP and pain sensitivity were not related in PF women. In men, but not in PF or TMD women, stress systolic and diastolic BP were positively correlated with heat pain threshold and tolerance and higher diastolic reactivity to stress were correlated with higher heat pain and IPTh and tolerance. On the stress day, higher baseline E level was strongly associated with higher IPTol in PF women but marginally associated with lower IPTol in TMD women. Thus, it appears that a BP-related analgesic mechanism (probably baroreceptor-mediated) predominates in PF men, while an endogenous opioid mechanism predominates in PF women. Stress enhances the expression of these central mechanisms. Female TMDs appear unable to effectively engage normal pain-inhibitory systems; opioid receptor desensitization and/or downregulation are probably implicated, because TMDs' production of E appears normal.

Adult↗

PubMed2002

Temporomandibular disorder and optimism: relationships to ischemic pain sensitivity and interleukin-6.

The current study examined patients with temporomandibular disorders (TMD) (n=20) and pain-free controls (n=28) under stress and relaxation conditions. Interleukin-6 (IL-6), norepinephrine and epinephrine (NE and E) were measured both before and during each of two conditions: a non-stressful relaxation period and a speech stressor. Ischemic pain sensitivity was also assessed after each of these conditions. Optimism (Life Orientation Test (LOT)), which has been associated with better outcomes in relationship to health and disease, was also evaluated in relationship to ischemic pain tolerance and unpleasantness ratings as well as to IL-6 levels under the two conditions. Regression analysis determined the unique contribution of each predictor and the interaction between Optimism and Group (TMD versus controls) after controlling for gender and blood pressure. During stress, IL-6 levels appeared to parallel NE with only controls displaying significant increases. After controlling for depressed mood, TMD patients as a whole showed a significantly blunted response in IL-6 levels produced during stress as compared to controls (beta=0.31*). Although TMD subjects as a whole did not show the expected greater pain sensitivity to the ischemic task, those displaying a less optimistic style did exhibit lower pain tolerance times (beta=-0.61*) and higher pain unpleasantness ratings (beta=0.48*), compared with low optimism controls and high optimism TMD patients. Less optimistic TMD patients also had higher NE and IL-6 levels during stress than other TMD patients, while optimism was unrelated to responses in controls (*P<0.05).

Adult↗

PubMed2002

Menstrual cycle, beta-endorphins, and pain sensitivity in premenstrual dysphoric disorder.

This study examined pain sensitivity and pain modularity mechanisms (e.g., beta-endorphin levels, blood pressure) in women with premenstrual dysphoric disorder (PMDD; n = 27) and healthy controls (n = 27) during the follicular and luteal phases of the menstrual cycle. Physiological measures were taken during rest and ischemic pain testing. In both cycle phases, PMDD women (a) displayed lower resting cortisol and beta-endorphin levels and (b) exhibited shorter pain threshold and tolerance times and greater pain unpleasantness ratings during pain. PMDD women also reported greater pain unpleasantness and intensity and had lower beta-endorphin levels in their luteal phase and tended to display higher blood pressure levels at rest and during pain testing. Results suggest that endogenous opioids may be pathophysiologically relevant to PMDD and that the hypothalamic-pituitary-gonadal axis may modulate pain sensitivity in PMDD.

Adult↗

PubMedDate not supplied

Biological correlates of abuse in women with premenstrual dysphoric disorder and healthy controls.

OBJECTIVE: To examine the biological correlates associated with histories of sexual or physical abuse in women meeting DSM criteria for premenstrual dysphoric disorder (PMDD) and in healthy, non-PMDD controls. METHODS: Twenty-eight women with prospectively confirmed PMDD were compared with 28 non-PMDD women for cardiovascular and neuroendocrine measures at rest and in response to mental stressors, and for beta-adrenergic receptor responsivity, during both the follicular and luteal phase of the menstrual cycle. Structured interview was used to assess psychiatric history and prior sexual and physical abuse experiences. All subjects were free of current psychiatric comorbidity and medication use. RESULTS: More PMDD women had prior sexual and physical abuse experiences than controls (20 vs. 10, respectively). Relative to nonabused PMDD women, PMDD women with prior abuse (sexual or physical) exhibited significantly lower resting norepinephrine (NE) levels and significantly greater beta1- and beta2-adrenoceptor responsivity and greater luteal phase NE reactivity to mental stress. For non-PMDD control women, abuse was associated with blunted cortisol, cardiac output, and heart rate reactivity to mental stress relative to nonabused controls. CONCLUSIONS: The results of this initial study suggest that a history of prior abuse is associated with alterations in physiological reactivity to subsequent mental stress in women, but that the biological correlates of abuse may be different for PMDD vs. non-PMDD women.

Adult↗

PubMedDate not supplied

Depressive symptoms are related to higher ambulatory blood pressure in people with a family history of hypertension.

OBJECTIVE: We investigated whether parental history of hypertension (FH+) enhances the impact of depressed mood, indexed by Beck Depression Inventory (BDI), on ambulatory blood pressure (ABP). METHODS: Twenty-four-hour ABP, urinary norepinephrine (NE), and cortisol were obtained in 314 unmedicated normotensive and hypertensive men and women (age 18-64 years) who also completed the BDI. RESULTS: Subjects with a positive family history of hypertension (N = 177) exhibited significantly greater mean body mass index (BMI) and ABP compared with subjects without (N = 137). Importantly, when covarying for age, BMI, gender, and race, linear regressions revealed significant FH by BDI interactions. Higher BDI scores were significantly associated with higher 24-hour ABP in FH+ subjects, but not in FH- participants. Relationships were significantly stronger in those with two hypertensive parents vs. those with one vs. those with no hypertensive parents. Increases in BDI scores were significantly related to greater heart rate (HR) and 24-hour urinary NE in both FH+ and FH- groups, although no evidence of a mediational role for NE in the effect of BDI score on blood pressure (BP) or HR was seen. CONCLUSIONS: These findings suggest that depressed mood may be reliably associated with higher BP only among those with an underlying susceptibility to HTN.

Adolescent↗

PubMedDate not supplied

Historical sexual abuse and current thyroid axis profiles in women with premenstrual dysphoric disorder.

OBJECTIVE: This study investigated whether women with premenstrual dysphoric disorder (PMDD) who also had histories of sexual abuse differed from women with PMDD with no previous sexual abuse and from women without PMDD in hypothalamic-pituitary-thyroid (axis measures). METHODS: Ten sexually abused women with PMDD were compared with 18 nonabused women with PMDD and 22 nonabused women without PMDD for hypothalamic-pituitary-thyroid axis hormone concentrations during the follicular and luteal phases of confirmed ovulatory cycles. RESULTS: Compared with the women without PMDD, only the group of women with PMDD with sexual abuse showed greater variance in both cycle phases in thyroid-stimulating hormone concentrations and greater luteal phase variance in free and total thyroxine (T4) and reverse tri-iodothyronine (T3). In the group of nonabused women with PMDD, there was greater variance in follicular phase thyroxine-binding globulin concentrations compared with the group without PMDD. Women with PMDD with abuse had greater mean concentrations of total T3 and thyroxine-binding globulin, greater total T3/free T4 and free T3/free T4 ratios, and lower ratios of free T3/total T3 and free T4/total T4 than either of the other 2 nonabused groups. Greater total T3 concentrations and histories of major depression independently predicted premenstrual symptoms in all women with PMDD, together accounting for 31% to 38% of the variance in anxiety, anger, and depression ratings. CONCLUSIONS: These results suggest increased conversion of T4 to T3 and increased binding of thyroid hormones in women with PMDD with previous sexual abuse. Abnormal total T3 concentrations may have pathophysiological significance in PMDD.

Adolescent↗

PubMedDate not supplied

Effects of partner support on resting oxytocin, cortisol, norepinephrine, and blood pressure before and after warm partner contact.

OBJECTIVE: We examined whether the magnitude of plasma oxytocin (OT), norepinephrine (NE), cortisol, and blood pressure (BP) responses before and after a brief episode of warm contact (WC) with the spouse/partner may be related to the strength of perceived partner support. METHODS: Subjects were 38 cohabiting couples (38 men, 38 women) aged 20 to 49 years. All underwent 10 minutes of resting baseline alone, 10 minutes of WC together with their partner, and 10 minutes of postcontact rest alone. RESULTS: Greater partner support (based on self-report) was related to higher plasma oxytocin in men and women across the protocol before and after WC. In women, higher partner support was correlated with lower systolic blood pressure (SBP) during solitary rest after WC but not before. Also, higher OT in women was linked to lower BP at baseline and to lower NE at all 4 measurements. CONCLUSION: Greater partner support is linked to higher OT for both men and women; however, the importance of OT and its potentially cardioprotective effects on sympathetic activity and BP may be greater for women.

Adult↗

PubMedDate not supplied

African Americans show alterations in endogenous pain regulatory mechanisms and reduced pain tolerance to experimental pain procedures.

OBJECTIVES: To examine ethnic differences in pain sensitivity and relationship of pain tolerance to blood pressure and neuroendocrine factors. METHODS: Fifty-one African Americans (24 men, 27 women) and 55 people from other ethnic groups (primarily Caucasian; 26 men, 29 women) were tested twice for pain sensitivity to tourniquet ischemia, thermal heat, and cold pressor tests, once following mental stress and once following rest control. Resting and stress-induced blood pressure (BP), plasma norepinephrine (NE), and cortisol were assessed. RESULTS: In response to all three pain tests, African Americans had lower pain tolerance relative to Caucasian/Others after both rest and stress. Only the non-African American group showed the expected inverse relationship between BP and pain sensitivity. African Americans had lower cortisol concentrations at rest and stress and showed blunted NE and systolic BP responses to stress. Only in Caucasians/Others was the relationship seen between higher stress-induced BP, cortisol, and NE levels and greater pain tolerance. CONCLUSIONS: The results suggest that there are alterations in endogenous pain regulatory mechanisms involving BP, cortisol, and NE in African Americans. Such dysregulation may contribute to the greater rate of clinical pain symptoms they experience. It is hypothesized that greater chronic stress in African Americans may be a contributing factor to the alterations in pain regulation.

Adolescent↗