Biological Research For Nursing current issue

A Decade of Dedication to Biological and Biobehavioral Research in Nursing

Yucha, C. B., Wiss, M. — 2008-09-30

Arginine Metabolites in Wound Fluids From Pressure Ulcers: A Pilot Study

Childress, B., Stechmiller, J. K., Schultz, G. S. — 2008-09-30

Compelling evidence suggests that nitric oxide (NO^•), a metabolite of arginine, plays an important role in wound healing. Arginine is a semi-essential amino acid that is metabolized by nitric oxide synthase and arginase. One model for wound-healing regulation suggests the importance of strict reciprocal control of these enzymes in wounds. The purpose of this pilot study was to investigate arginine metabolism in wound fluids from patients with Stage III or IV pressure ulcers receiving negative pressure wound therapy (NPWT). Wound fluids were collected from 8 patients, aged 31—79 years, before and after initiation of NPWT on Days 1, 3, and 7. Wound fluids were analyzed for nitrates/nitrites (NO_x), arginine, citrulline, proline, and ornithine. There were no significant differences between NO_x, arginine, citrulline, proline, and ornithine concentrations before and after initiation of NPWT among the various timepoints. However, we observed a downward trend of NO^• levels from baseline to Day 7 of NPWT treatment. Furthermore, we detected a decrease in arginine levels over the study period, suggesting that the iNOS/citrulline pathway predominated during the first 72 hr of treatment, and the arginase/ ornithine pathway dominated thereafter. Arginine and its metabolites are detectable in wound fluids from patients with Stage III or IV pressure ulcers on NPWT. Further studies on chronic wounds are warranted to correlate wound-healing outcomes with arginine metabolites at the cellular and molecular level over a longer period of time.

Exogenous Irritant-Induced Airway Hyperreactivity and Inhibition of Soluble Guanylyl Cyclase

Antosova, M., Strapkova, A., Turcan, T. — 2008-09-30

The majority of nitric oxide (NO) effects in the respiratory system are caused by stimulation of soluble guanylyl cyclase (sGC) with subsequent increase of cyclic guanosine monophosphate (cGMP) production. The importance of this mechanism of NO action in airway hyperreactivity (AHR) pathogenesis is unknown. Therefore, the aim of our experiment was to examine the changes of airway reactivity enhanced by toluene vapor exposure in the presence or inhibition of sGC activity in guinea pigs. Animals were treated with a nonspecific sGC inhibitor, methylene blue, in a dose of 50 or 100 mg/kg body weight, administered by intraperitoneal injection 30 min before or after exposure to toluene vapors. The toluene exposure lasted 2 hr in each of 3 consecutive days under in vivo conditions. Thereafter, the tracheal and lung tissue smooth muscle response to cumulative doses of mediators (histamine or acetylcholine) was recorded under in vitro conditions. The exposure to toluene vapors significantly increased the airway reactivity to both mediators in comparison with the healthy animal group. The administration of methylene blue decreased the amplitude of airway smooth muscle contraction in toluene-induced hyperreactivity. The decreases were dependent on the inhibitor doses, on a regimen of administration (before or after toluene inhalation), the level of the respiratory system (trachea, lung), and the bronchoconstrictor mediators. Our results suggest that the interaction between NO and sGC may be important for airway reactivity changes, but other mechanisms of NO action are important in AHR pathogenesis, too.

Cerebrospinal Fluid Apolipoprotein E, Calcium and Cerebral Vasospasm after Subarachnoid Hemorrhage

2008-09-30

Intracellular calcium (Ca⁺⁺) regulation of cerebral vessels is impaired after subarachnoid hemorrhage (SAH), making secondary pathways, such as that involving apolipoprotein E, potentially more influential. To evaluate cerebrospinal fluid (CSF) apolipoprotein E and Ca⁺⁺ levels as biomarkers of cerebral vasospasm, we examined changes in levels over time and apolipoprotein E (APOE) 4 allele presence after SAH in individuals with and without vasospasm. We hypothesized that individuals with low apolipoprotein E levels, increased Ca⁺⁺ levels and/or at least one copy of the APOE 4 allele would have vasospasm. Daily samples from 50 participants, aged 18—75, with SAH were used to quantify apolipoprotein E and Ca⁺⁺ levels. Vasospasm was verified using cerebral angiogram and/or elevated transcranial Dopplers in combination with clinical neurologic deterioration. Overall apolipoprotein E levels were higher in individuals with the APOE 4 allele (p = .02) or angiographic vasospasm (p = .01), but there were no differences between individuals with and without symptomatic vasospasm. There were no significant changes in apolipoprotein E levels over time. Individuals with the 4 allele had lower Ca⁺⁺ levels (p = .02) with trends suggesting a different pattern of change over time (p = .07). CSF Ca⁺⁺ levels were lower in individuals with symptomatic vasospasm (p < .01). Change in apolipoprotein E and Ca⁺⁺ levels (p = .006) correlated over time regardless of genotype or vasospasm status. These findings suggest that apolipoprotein E and Ca⁺⁺ may be interacting after SAH, but this interaction does not appear to influence vasospasm.

Cerebrospinal Fluid Phospholipid Changes Following Traumatic Brain Injury

Pasvogel, A. E., Miketova, P., Moore, I. M. — 2008-09-30

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality, with approximately 1.4 million people suffering a TBI each year. With TBI, a cascade of events is initiated including the activation of phospholipases, which leads to the disruption of the lipid bilayer of the membrane of neurons and neuroglia. The purpose of this study is to describe phospholipid changes following TBI. A total of 39 cerebrospinal fluid samples were obtained from the ventricular catheter system of 10 participants who received a TBI as a result of a motor vehicle crash, being struck by a vehicle as a pedestrian, or a fall. Phospholipids were extracted from samples and measured by normal-phase high-performance liquid chromatography with ultraviolet detector at a wavelength of 206 nm. The highest mean concentration of lysophosphatidylcholine occurred on Day 1 after injury. The concentration of phosphatidylserine was variable, with the highest mean concentration occurring on Day 2 after injury. The highest mean concentrations of phosphatidylethanolamine, phosphatidylcholine, and sphingomyelin occurred on Day 4 after injury. Findings provide preliminary evidence for disruption of central nervous system membrane phospholipids following TBI.

White Matter Hyperintensities and Medication Adherence

Insel, K. C., Reminger, S. L., Hsiao, C.-P. — 2008-09-30

White matter hyperintensities (WMH) are associated with hypertension, age, and cognitive function, but the association between WMH and medication adherence has not been examined. The intent of this investigation was to consider the potential implications of hypertension-related brain morphological changes on medication adherence and thereby improve understanding of the self-management consequences of hypertension. The associations between WMH, blood pressure, age, cognitive function (specifically assessments of prefrontal function), and medication adherence were examined in 16 middle-aged and older adults self-managing at least one prescribed antihypertensive agent. Magnetic resonance imaging using an axial fluid attenuated inversion recovery (FLAIR) sequence was used to assess the presence of WMH. Cognitive assessments included measures of executive function, working memory, attention, and immediate recall. Adherence was monitored for 8 weeks using electronic medication monitoring. More WMH were associated with poorer adherence (r_s = —.25) and with higher systolic blood pressure (r_s = .46), although these relationships were not statistically significant. WMH were associated with cognitive assessments in the expected direction including Digit Span Backward (r_s = —.53, p < .05). Adherence was associated with immediate memory (r_s = .54, p < .05) and inversely associated with failure to maintain set on the Wisconsin Card Sorting Test (WCST; r_s = —.61, p < .05). These findings provide preliminary evidence for the association between WMH, assessments of prefrontal function, and medication adherence.

Symptoms of Postpartum Depression Associated With Elevated Levels of Interleukin-1 Beta During the First Month Postpartum

Corwin, E. J., Johnston, N., Pugh, L. — 2008-09-30

Postpartum depression (PPD) is a devastating disorder that may carry lifetime consequences. Although several psychosocial risks for PPD have been identified, biological contributors are unclear. Elevated inflammatory cytokines contribute to depression in nonpregnant, nonpostpartum populations; yet, their role in PPD has been minimally studied. The objective of this study is to determine whether inflammatory cytokines early in the postpartum period contribute to the development of PPD. Women were recruited within 24 hr of delivery, and 26 provided urine for analysis of interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) on postpartum days 7, 14, and 28. Participants completed a depression symptom survey (Centers for Epidemiologic Studies Depression Scale; CES-D) on Day 28. An increase in IL-1β was seen on Day 14 in women with symptoms of depression (CES-D ! 11) on Day 28 compared to levels in women without depressive symptoms (F = 4.50, p = .045). These preliminary findings suggest elevated IL-1β early in the postpartum period may increase the risk of PPD. Further studies involving a larger sample of women, including those clinically diagnosed with PPD, are required.

Maternal Heart Rate Variability and Fetal Behavior in Hypertensive and Normotensive Pregnancies

Brown, C. A., Lee, C. T., Hains, S. M. J., Kisilevsky, B. S. — 2008-09-30

The relation between maternal heart rate variability (HRV) and fetal behavior was examined in hypertensive and normotensive pregnant women. A total of 40 mother—fetal pairs (n = 20 normotensive mothers; n = 20 hypertensive mothers) at 33—41 weeks' gestation were observed using a standardized procedure lasting approximately 50 min. It included the following measurements: maternal beat-by-beat arterial blood pressure and HRV; spontaneous fetal heart rate (HR), body and breathing movements; and an estimate of amniotic fluid volume. The women in the hypertensive group had higher average body mass index (BMI) (33.7 vs. 28.8 kg/m² ) than the normotensive group. In the normotensive group, there was no association between maternal HRV and fetal gestational age, HR, body or breathing movements. In the hypertensive group, maternal HRV measures of low-frequency, high-frequency, and total power were associated with fetal gestational age; also, there was an association between maternal autonomic modulation of HR and fetal spontaneous HR. These findings suggest that the maternal autonomic system influences fetal cardiac function in pregnancies complicated by hypertension.

Gestational Diabetes Mellitus: Physical Exercise and Health Outcomes

Snapp, C. A., Donaldson, S. K. — 2008-09-30

Purpose: Gestational diabetes mellitus (GDM) is a serious complication of pregnancy associated with increased risk of adverse outcomes for both mother and infant. This study assesses the association of maternal exercise during GDM pregnancy and selected maternal and infant adverse GDM-related outcomes. The analysis uses information derived from the 1988 National Maternal Infant Health Survey (NMIHS) data. Methods: Women in the 1988 NMIHS database were identified and grouped as to having experienced a non-GDM (n = 2,952,482) or GDM (n = 105,600) pregnancy. Non-GDM and GDM groups were compared as to demographic and personal-attribute variables. The second part of this study focused on the women with GDM pregnancy, specifically a subset (n = 75,160) who met inclusion/exclusion criteria for the study of exercise during pregnancy. Each was categorized to either the exercise group or the nonexercise group. Results: The non-GDM and GDM groups of pregnant women were not different as to the variables studied, except that older age and increased body mass index (BMI) were associated with GDM pregnancy. For the study of exercise during GDM pregnancy, the only variable that was associated with the exercise group was size of the infant. Participants in the exercise group were less likely than those in the nonexercise group to have delivered a large for gestational age (LGA) infant (F [1, 4314] = 9.82, p = .0017). Implications: The results of this study suggest that moderate maternal leisure time physical exercise during GDM pregnancy may reduce the risk of delivery of an LGA infant.

A Systematic Review of Exercise Interventions in Patients With Heart Failure

Tai, M.-K., Meininger, J. C., Frazier, L. Q. — 2008-09-30

The incidence of heart failure (HF) is increasing as the population ages. Pharmacotherapy is an important component of treatment and yields significant improvements in survival and quality of life. In recent decades, exercise has gradually become accepted as an intervention beneficial to patients with HF, but more information is needed to clarify the effects of exercise and optimize interventions. Therefore, a systematic review of randomized controlled trials published from 1966 to October 2006 was carried out via PubMed. About 69 trials were reviewed, which used as main outcome measures: (a) central hemodynamic parameters, (b) peripheral blood flow, (c) endothelial function, (d) activation of neurohormones and cytokine systems, (e) structure of and metabolism in skeletal muscles, and/or (f) quality of life. Study findings suggest that the favorable physiological responses to exercise might slow some of the pathophysiological progression of HF. However, most of the trials reviewed here were based on relatively small samples and selected participant groups, and the exercise programs varied widely. These limitations and inconsistencies need to be addressed through further studies. Furthermore, reliable strategies for maintaining the positive effects of exercise and extending them to patients' daily life and quality of life are scarce in these trials. These domains need further exploration through rationally designed, large-scale randomized controlled trials.

The Relationship Between Job Stress and Urinary Cytokines in Healthy Nurses: A Cross-Sectional Study

2008-09-30

Cytokines such as angiogenin (ANG) and interleukin (IL-8) have been shown to be related to depressive symptoms and inflammatory diseases like coronary heart disease. They may thus be used as stress biomarkers to identify and prevent health problems. To investigate the relationship between cytokines and nurses' job-related stress, levels of urinary ANG and IL-8 were measured in healthy female hospital nurses in Japan. The level of job-related stress of the subjects was evaluated using the Nursing Stress Scale (NSS), with the participants being classified into high- or low-stress groups for each subscale according to their scores. The participants' subjective psychological states were assessed using the Profile of Mood States—Short Form Japanese version (POMS-SFJ). Urinary ANG, IL-8, and cortisol levels and subjective psychological states for two groups were compared for each NSS subscale. The fatigue and depression scores of POMS-SFJ subscales in the present study were higher than those of the general healthy Japanese population. Based on the mean score of the combined participants, nurses were experiencing the highest stress related to the pressure of having responsibility for patients' life support care (PPLC). Nurses reporting high levels of stress related to PPLC and conflict with physicians had high levels of urinary ANG. Urinary ANG levels may thus be associated with high levels of job stress.