Biological Research For Nursing

Spatial disorientation frequently occurs in conditions such as Alzheimer’s disease that damage the hippocampus, a brain structure necessary for learning and memory. Use of a single cue to mark a submerged escape platform in the Morris water test can reduce spatial disorientation in rats. If the cue used is a familiar one, disoriented rats perform the wayfinding task as well as control animals. However, in a real-world environment, cues rarely occur alone. This study examined whether rats with bilateral hippocampal lesions familiar with a cue performed the Morris water test as well as controls and faster than lesioned rats unfamiliar with the cue when a distracter was present. Bilateral electrolytic lesions were made in male rats that had received either familiarity with a cue or handling only. Familiar lesioned rats were introduced to the distracter on test days 1 (FB1) or 3 (FB3), and unfamiliar lesioned rats on day 3 (UB3). No significant differences were found for FB1 or FB3 rats and their respective controls. FB1 rats increased mean swim times on day 1 compared to preoperative day 4 (16.44 ± 4.3 vs. 4.06 ± 2.1 s, respectively, p< 0.03) but quickly adapted to the distracter. FB3 rats were slower than FB1 rats on day 3 (6.81 ± 1.0 vs. 4.56 ± 0.3 s, respectively, p < 0.05). UB3 rats were impaired on the task compared to FB1 rats on days 3-7 (p < 0.05). These findings suggest that cue familiarity is effective in the presence of a distracter and that the response of disoriented rats to a distracter is influenced by the amount of prior experience with the cue.

The purpose of this study was to examine the role of the pulmonary afferent receptors in producing hemodynamic changes during hyperinflation and endotracheal suctioning (ETS) in an oleic acid–injured animal model of acute respiratory failure. Previous investigations of hyperinflation as a method to prevent hypoxia-induced sequelae of ETS have demonstrated unrecognized hemodynamic consequences. In this within-subject, repeated-measures study, instrumented, oleic acid–injured dogs had continuous measurements of heart rate (HR), mean aortic blood pressure (MAP), left ventricular pressure (Plv), pulmonary artery pressure (Ppa), right ventricular afterload (Ppa(tm)), right atrial pressure (Pra), and right ventricular filling pressure (Pra(tm)) during hyperinflation and ETS when the vagi were intact and after the pulmonary branches of the vagus nerves had been severed. After severing the vagi, MAP and Plv were decreased and HR and Ppa were increased. With the vagi severed, there was less variation in MAP and Ppa but increased variation in HR. These findings suggest that vagally mediated reflexes from the lungs produce some, but not all, of the hemodynamic effects associated with hyperinflation and ETS. Continued research is necessary to discover a method of hyperoxygenation and suctioning that does not produce potentially harmful hemodynamic effects.

Abuse of women by their intimate partner is a staggering national problem. Abused women have a higher number of medically unexplained somatic symptoms, more functional disability, a lower selfrating of general health, and higher health care utilization when compared to nonabused women. The authors’ purpose in this study was to examine differences in occurrences of negative life experiences, level of depression, and T-cell function between abused and nonabused women. The sample consisted of abused women (n = 12) and nonabused women (n = 12). Hypotheses tested were (1) abused women will have more negative life experiences than nonabused women, (2) abused women will have higher levels of depression than nonabused women, and (3) abused women will have reduced T-cell function compared to nonabused women. A cross-sectional cohort design was used to compare differences in negative life experiences, levels of depression, and T-cell function. Independent samplet-tests were performed comparing the abused versus nonabused women on the dependent measures. Significant differences were found between the groups for negative life experiences (LES;t = 2.29,p< 0.05), level of depression (BDI;t= 3.48,p< 0.01), and T-cell function (TMR;t = –5.62,p < 0.01). These findings are descriptive and do not establish causal links. However, this is an inquiry into the psychological and biobehavioral responses of women experiencing abuse and their potential health problems. The study shows that abused women reported more negative life experiences, experienced higher levels of depression, and experienced lower T-cell function when compared with nonabused women.

In this retrospective study employing chart reviews, 75 open heart surgery patients (OHSPs) were divided into 3 groups of 25 patients. Group 1 received no intravenous (IV) norepinephrine (NE) after surgery. Group 2 and group 3 received a minimum of 0.028 mcg/kg/min of IV NE for 6-24 h and greater than 24 h, respectively. In the 3 groups, preoperative lymphocyte counts were compared to counts obtained on postoperative days 1 and 2. The results showed lower lymphocyte counts on postoperative day 2 in group 3 subjects, who received NE for 24 h or more, compared to subjects of the other groups who received no NE or 6-24 h of NE (p < 0.05). There was also evidence that preoperative use of beta-blocking agents significantly affected the change in lymphocyte counts from day 1 to day 2 in both groups receiving NE. Furthermore, postoperative infections were more prevalent in group 3 than the other 2 groups (p < 0.05). The lower lymphocyte counts and higher infection rate, however, may be linked to lower postoperative blood pressure and increased number of intensive care unit days in group 3. Further investigation is warranted to elucidate the effects of IV NE administration on the lymphocyte counts of OHSPs and to reduce infections in those receiving NE.

Angiotensin II (ANG II), the effector hormone of the renin-angiotensin system (RAS), has been implicated in the pathophysiology and progression of heart failure. Therefore, the measurement of ANGII has become important to characterize the role of this neurohormone in heart failure. However, because ANG II has been difficult to measure, other components of the RAS have been measured to characterize ANG II production. The RAS components (e.g., renin, angiotensin I–converting enzyme [ACE], angiotensin II) have been measured with a variety of techniques. In this review, RAS physiology and the techniques used to measure the RAS components are discussed. In addition, the advantages and disadvantages of the RAS measurement methods are described.

Pain is not simply a physiologic event, but a dynamic process that involves continuous interaction among complex systems. Nurses have the unique disciplinary background to envision the pain process within the context of the whole dynamic human being. Understanding the human condition in this holistic manner prepares nurses to develop clinically relevant research questions. Many of these research questions can best be answered initially through basic science research. Basic science research by a nurse will be distinct from other disciplines from the inception of the hypothesis through the conclusions drawn to the delineation of areas for further research. This article provides a few examples of basic science research in the area of pain by nurse researchers. The research includes both cellular and animal models and describes the relationship of the research to clinical practice. Patient care will ultimately benefit from clinically relevant research whether the methodology used is basic science or other methods.

Even with all the nutritional research conducted to date, it is not clear which enteral nutrition delivery and composition options are most physiologically sound. Glucocorticoid temporal patterns are reported to be shifted or disrupted with restricted feeding schedules, but because of intermittent sampling, temporal patterns have not been completely depicted. The purpose of this study was to characterize corticosterone temporal patterns while systematically varying selected enteral feeding options in a well-established nutritional animal model. A 2• 2 • 2 • 2 randomized block experimental design was used in which enteral feeding schedules, delivery methods, kilocalorie levels (kcal), and fiber contents were systematically varied in rats (n = 80), and plasma corticosterone was measured by125I radioimmunoassay. Blood samples were drawn hourly over 24 h. With cosinor analysis, 24-h and 12-h corticosterone rhythmic components were tested in each feeding group. Five of 16 feeding groups had a significant (p £ 0.05) 24-h rhythmic component, and 3 more showed a trend (p> 0.05< 0.10); 7 of these groups were on 24-h feeding schedules. When rhythmic components were detectable, groups receiving high-fiber formula displayed more uniform rhythm characteristics than did no-fiber groups. Only 1 group had a significant 12-h rhythmic component, and 1 showed a trend. Both were on 12-h, high-fiber restricted kcal feedings. In this small animal sample, no one enteral feeding option guaranteed a 24-h corticosterone pattern. The option coming closest was formula delivered on a 24-h schedule. This temporal pattern is one aspect to consider in enteral nutrition. The underlying mechanisms have yet to be elucidated.