Biomedical subjects

Maria M Llabre

Publications and source records attributed to Maria M Llabre.

11 recordsLinked to original sources

PubMed2006

Social experience influences hypothalamic oxytocin in the WHHL rabbit.

Social experience influences behavior and the progression of atherosclerosis in the Watanabe Heritable Hyperlipidemic (WHHL) rabbit, such that WHHL rabbits exposed to a consistent, stable social experience exhibited more affiliative social behavior and less aortic atherosclerosis compared to other social groups. Oxytocin (OT) has been implicated in the expression of social behavior, stress responses, and may provide a mechanism by which social experience influences atherogenesis in WHHL rabbits. The current study examined acute and chronic changes in central and peripheral OT before and after WHHL rabbits were exposed to one of three social conditions. Cannula implanted adjacent to the hypothalamic paraventricular nucleus (PVN) allowed chronic sampling of extracellular OT concentration via microdialysis. Rabbits were exposed to one of three social conditions: an Unstable group, with initially unfamiliar rabbits paired daily for 4h during the initial week and similarly paired with a different, unfamiliar rabbit each week; a Stable group; with the same 2 littermates paired daily for 4h the entire study; and an Individually Caged group. Dialysates from the PVN and blood from the marginal ear vein were collected twice, 20 days apart, from rabbits before and after 2h of exposure to their respective social condition. Dialysates were assayed for OT and plasma was assayed for OT, catecholamines and glucocorticoids. There were no changes in PVN OT in any group following the initial social experience. In contrast, after 20 consecutive days of exposure to their respective social condition, PVN OT increased significantly in the Unstable group, but was relatively unchanged in the Stable group following the social experience on day 22. Peripheral OT was not altered in any group following the 2h social experience on day 1 or 22. The concentration of peripheral OT was the highest in the Stable group at all times. The Stable group also exhibited significantly less aortic atherosclerosis, consistent with earlier findings from our laboratory. Data from the present study suggest that the type of social experience WHHL rabbits are exposed influences PVN OT, social behavior and the progression of atherosclerosis in the WHHL rabbit model of disease.

Analysis of Variance↗

PubMed2006

A measurement model of medication adherence to highly active antiretroviral therapy and its relation to viral load in HIV-positive adults.

This study compared a multiple method measurement model of highly active antiretroviral therapy (HAART) adherence with single-method models to determine optimal validity in predicting HIV viral load. Repeated measures of antiretroviral adherence were collected over a 15-month period using three different measurement methods: a self-report questionnaire, an adherence interview item, and electronic medication monitoring. The participants included HIV-positive men and women (n = 323) who were currently prescribed HAART. Single-factor models composed of multiple measurements over time were developed for each adherence method and HIV viral load. The three adherence methods were then combined in a second order factor measurement model. Structural equation modeling was used to test the models. Mean adherence, defined as percent of doses taken, was 92%, 90%, and 57% by self-report, interview, and electronic monitoring, respectively. Reliability of individual measurements of adherence was low. Four or seven assessments were needed to attain acceptable stability, depending on the method. The second-order factor model of adherence fit the data and explained 45% of the variability in HIV viral load. Models including only one method of assessing adherence explained between 20% and 24% of the variability. Models that included both self-report and electronic monitoring optimized predictive validity. Using at least two different methods of adherence measurement, each assessed at multiple times is recommended to derive reliable and valid measurement of medication adherence, which is predictive of biological outcomes such as HIV viral load.

Adolescent↗

PubMed2005

Is the factor structure of the metabolic syndrome comparable between men and women and across three ethnic groups: the Miami Community Health Study.

PURPOSE: The metabolic syndrome (MS) is conceived as a cluster of disorders that increase risk for coronary heart disease and type 2 diabetes. Studies examining its structure primarily have used an exploratory factor analytic technique, but yielded discrepant results. There also is a lack of research that investigates whether the clustering pattern is similar across sex and ethnic groups. This study uses confirmatory factor analysis to evaluate the factor structure of the MS and examines its similarity between men and women and across three ethnic groups (Caucasian, African, and Cuban Americans). METHOD: A hierarchical four-factor model with an overarching MS factor uniting insulin resistance, obesity, lipid, and blood pressure factors was tested with 517 individuals from the Miami Community Health Study. RESULTS: Findings show that the proposed structure was well supported (comparative fit index=0.97) and similar between men and women and across ethnic groups. The MS was represented strongly by insulin resistance, followed by obesity, lipid factors, and, to a lesser extent, a blood pressure factor. CONCLUSIONS: This study provides empirical support for identifying and diagnosing the MS by its component factors in a diverse population.

Adult↗

PubMed2005

Behavioral indices of threat and challenge in Hispanic adolescents and hemodynamic responses to a speech stressor.

Behavioral ratings of performance and nervousness during a speech were used to divide participants (n=54) into threat and challenge groups. Comparisons on cardiac output, Heather index, heart rate, vascular resistance, and blood pressure reactivity indicated greater myocardial responses for the challenge group. This study extends the threat-challenge literature by employing behavioral definitions of constructs and examining a Hispanic adolescent sample.

Adolescent↗

PubMed2004

Ethnicity, gender, and age effects on adrenoceptors and physiological responses to emotional stress.

We examined the unique and joint effects of ethnicity, gender, and age on cardiovascular and catecholamine responses to the anger recall interview, and beta(2)-adrenergic receptor density and function on peripheral blood mononuclear cells. Participants were 179 nonsmoking, normotensive men and women aged 18-49 years. All subjects showed similar blood pressure increases during the anger recall interview. Black men, however, showed the smallest increases in heart rate in conjunction with an attenuated peripheral vasodilatation. Black women and Whites showed similar increases in heart rate and peripheral vasodilatation. Increasing age was associated with greater norepinephrine increases to anger recall in Black males. Black men also exhibited higher epinephrine levels throughout the protocol, higher dissociation constant to (125)I-pindolol, and age-dependent increases in beta(2)-receptor density. Relative to Whites and Black females, arousal of negative affect in Black males led to a pattern of sympathetic nervous system activity that may help explain the higher prevalence of hypertension in this population.

Adolescent↗

PubMed2004

HIV, metabolic syndrome X, inflammation, oxidative stress, and coronary heart disease risk : role of protease inhibitor exposure.

Differences on measures of metabolic syndrome X and coronary heart disease (CHD) risk, as well as potential pathophysiological mediators, inflammation, and oxidative stress, were examined as a function of HIV serostatus and highly active antiretroviral therapy (HAART) regimen with and without protease inhibitors (PIs). Data from 164 men and women, aged 18 to 55 yr, were used to compare 82 HIV+ subjects who were free of hepatitis C virus and were on a stable HAART regimen for >/=6 mo, with 82 seronegative subjects matched on age, sex, body mass index, and ethnicity. For the HIV+ subjects, after controlling for diabetes status and HIV disease progression, PI exposure was associated with greater oxidative stress, triglyceridemia, and lipidemia than it was for non-PI-exposed HIV+ subjects, and the risk of a future myocardial infarction was up to 56% greater in PI-exposed than in non-PI-exposed subjects and 129% greater than in controls. Although it is likely that the greatest proportion of CHD risk in the HIV+ subjects may be accounted for by pathological conditions linked to HIV infection in interaction with mediating processes such as inflammation, central obesity, and dyslipidemia, which was greater than in controls, it appears that PI medications may exacerbate oxidative stress and hypertriglyceridemia to enhance this risk.

Adolescent↗

PubMed2003

Assessing the reliability and validity of the John Henry Active Coping Scale in an urban sample of African Americans and white Americans.

OBJECTIVES: The primary focus of this study was to examine the psychometric properties of the John Henry Active Coping scale (JHAC12) among an urban middle-aged sample of African Americans and white Americans. DESIGN: The sample consisted of 75 African Americans and 129 white Americans from South Florida ranging in age from 25 to 54 years. Subjects completed the JHAC12, the Life Orientation Test (LOT), Coping Orientation to Problems Encountered (COPE) subscales, and the Marlowe-Crowne Social Desirability scale. RESULTS: Major findings supported the validity and reliability of the JHAC12 among both African Americans and white Americans. For both the African American and white American subsamples, the JHAC12 was correlated with the active coping and suppression of competing activities subscales of the COPE and negatively correlated with the Marlowe-Crowne Social Desirability scale. In the African American subsample the JHAC12 was positively correlated with the LOT. The JHAC12 was also negatively associated with the behavioral disengagement subscale of the COPE among white Americans. Multiple regression analyses revealed that the proportion of variance in the JHAC12 explained by the various subscales of the COPE, Marlowe-Crowne, and the LOT was 43% for African Americans and 20% for white Americans. Factor analyses suggested two similar and meaningful factors among the African American and white American subsamples. Finally, Cronbach alpha reliabilities revealed similar subsample coefficients. DISCUSSION: The implications of the findings are discussed in terms of the JHAC12's ability to assess the construct of active coping among African Americans and white Americans.

Adaptation, Psychological↗

PubMed2002

Hemodynamic response patterns: responder type differences in reactivity and recovery.

We examined whether responder type groups reflecting patterns of hemodynamic reactivity might also differ in recovery responses. Cardiac output (CO), total peripheral resistance (TPR), systolic and diastolic blood pressure, heart rate, and Heather index were assessed at rest and during speech and cold pressor tasks in young adults. Participants (n = 152) were classified as myocardial, vascular, or mixed-mild responders based on CO and TPR responses to speech presentation. Vascular responders exhibited slower CO and TPR speech recovery than the myocardial and/or mixed-mild groups. Responder type differences in reactivity showed limited task-generalizability. The sustained vascular response pattern of the vascular group is consistent with that seen in hypertension. In light of associations of heightened TPR with markers of disease risk, this suggests potentially negative health implications for vascular responders.

Adolescent↗

PubMedDate not supplied

Psychological distress is associated with decreased memory helper T-cell and B-cell counts in pre-AIDS HIV seropositive men and women but only in those with low viral load.

OBJECTIVE: Although some studies have demonstrated the association of psychological distress and diminished immune system function in HIV spectrum disease, other studies have yielded apparently conflicting findings; the lack of consideration of the role of HIV viral burden may be central to this controversy. This study examined whether HIV viral burden moderated the relationship between psychological distress and enumerative and functional immune measures in pre-AIDS HIV spectrum disease. METHODS: This cross-sectional study used factor analysis to derive a composite measure of psychological distress incorporating measures of dysphoria, anxiety, and perceived stress. Multiple regression analyses used distress as the predictor, immune measures as the outcome variables, with viral load as the moderator variable, while controlling for age, medication use, and HIV symptomatology. Subjects were 148 pre-AIDS, HIV seropositive men and women (89 asymptomatic, 59 symptomatic), aged 18 to 45 years. The main outcome measures were enumerative and functional immune measures. RESULTS: A model of psychological distress was derived using each of the proposed measures. Findings indicated that high distress was associated with decreased numbers of helper T (memory) cells and B cells, but only at low levels of viral burden after controlling for age, medication use, and HIV-related symptoms. CONCLUSIONS: These findings highlight the importance of assessing the role of HIV viral burden when examining distress-immunity relationships in HIV-infected individuals. The lack of association in those persons with high viral load suggests that, even before AIDS onset, disease-related processes are disrupting CNS and immune system communication.

Adolescent↗

PubMedDate not supplied

Applying latent growth curve modeling to the investigation of individual differences in cardiovascular recovery from stress.

OBJECTIVE: This paper provides an introduction to latent growth curve (LGC) modeling, a modern method for analyzing data resulting from change processes such as cardiovascular recovery from stress. LGC models are superior to traditional approaches such as repeated measures analysis of variance and simple change scores. METHODS: The basic principles of LGC modeling are introduced and applied to data from 167 men and women whose systolic blood pressure was assessed before, during, and after the cold pressor and evaluated speech stressors and who had completed the Cook-Medley Hostility Inventory. RESULTS: The LGC models revealed that systolic blood pressure recovery follows a different nonlinear trajectory after speech relative to the cold pressor. The difference resulted not from the initial decline at the completion of the stressor, but from higher levels at the end of the stressor and slower rate of change in decline for the speech. Hostility predicted the trajectory for speech but not for cold pressor. This relationship did not differ as a function of gender, although men had larger systolic blood pressure responses than women to both stressors. CONCLUSIONS: LGC modeling yields an understanding of the processes and predictors of change that is not attainable through traditional statistical methods. Although our application concerns cardiovascular recovery from stress, LGC modeling has many other potential applications in psychosomatic research.

Adult↗

PubMedDate not supplied

Effect of behavioral interventions on insulin sensitivity and atherosclerosis in the Watanabe heritable hyperlipidemic rabbit.

OBJECTIVE: A previous study suggested that insulin metabolic variables play a role in the progression of atherosclerosis in Watanabe heritable hyperlipidemic (WHHL) rabbits. The present study sought to determine: 1) if young, individually caged WHHLs are insulin-resistant relative to New Zealand white (NZW) rabbits and 2) whether dietary or exercise interventions can improve insulin sensitivity and slow the development of atherosclerosis in these animals. METHODS: Forty-two WHHLs were assigned to a dietary, exercise, or control condition, and 12 NZWs were used as a comparison control group. The intervention ran from 3 to 7 months of age, and all animals received an intravenous glucose tolerance test at the beginning and end of the intervention. RESULTS: WHHLs were insulin-resistant relative to NZWs at 3 months of age. Whereas the dietary intervention was effective in controlling insulin resistance, WHHLs in the exercise group without dietary restriction and the control group exhibited significant increases in insulin resistance. No intervention significantly influenced the progression of atherosclerosis. CONCLUSIONS: Young WHHLs are insulin-resistant during an early period when atherosclerosis is developing rapidly. Dietary restriction, but not exercise without weight control, is effective in controlling insulin metabolic variables in the WHHL model. Although dietary intervention can reduce cardiovascular risk factors such as insulin resistance, it is not effective in slowing the development of atherosclerosis in these genetically dyslipidemic animals. Similarly, exercise training, without dietary control, does not influence the progression of disease in WHHLs.

Age Factors↗