Nondestructive room-temperature adsorption of 2,4,6-tri(2'-thienyl)-1,3,5-triazine on a Si-B interface: high-resolution STM imaging and molecular modeling.

Organic nanostructures on semiconductors are currently investigated but the surfaces are known to interact strongly with molecules. To reduce the molecule-surface interaction, we used the Si(111)-B square root 3 x square root 3R30 degrees . Deposition of isolated 2,4,6-tri(2'-thienyl)-1,3,5-triazine, was achieved at room temperature without modification of their pi skeleton. This fascinating arrangement, observed by STM, has been validated by full density functional theory computations onto the entire system. The theoretical results give a clear explanation for the specific adsorption sites of molecules on the substrate.

Impact of cognitive impairment on wandering behavior.

The purpose of this study was to explore cognitive impairment as a predictor of wandering rhythm and pattern in a sample of 25 demented residents from two long-term care settings. Parameters of rhythm indicating cycle frequency and structure were examined for wandering patterns (random, lapping, and pacing) and for nonwandering (direct) ambulation. All measures of cognitive impairment (Mini-Mental State Exam, Mattis Dementia Rating Scale, and a neuropsychologist's clinical rating) were significant predictors of parameters signifying frequency of wandering for random and lapping patterns but not for the pacing pattern. In addition, for nonwandering ambulation, cognitive impairment predicted some parameters of cycle structure (mean locomoting and nonlocomoting phase durations) but not those denoting frequency of ambulation. Results indicate that cognitive impairment plays an important role in determining the frequency of wandering cycles, but other factors may better explain parameters that characterize its cycle structure.

Effects of entorhinal cortex lesions on sensory integration and spatial learning.

BACKGROUND: The entorhinal cortex provides sensory information to the hippocampus for memory and learning. Damage to the entorhinal cortex is common in patients who experience traumatic brain injury, stroke, and Alzheimer's disease. Entorhinal damage is assumed to interfere with sensory integration; however, substantive knowledge of behavioral patterns is lacking. OBJECTIVES: To describe specific behavioral deficits associated with entorhinal cortex injury related to special senses identification, sensory integration, and spatial learning. METHOD: Adult male rats received bilateral entorhinal cortex damage (n = 19) or sham surgery (n = 11) with a subset randomized to participate in special senses identification, exploration, and sensory integration testing. Spatial learning was examined using a water maze. RESULTS: Lesion and control animals were similar in special senses identification testing. Sensory integration was markedly impaired in lesion animals over 3 days for all integration tasks; however, travel deficit persisted for 4 days. By day 5 sensory integration ability was equal. Lesion animals were significantly impaired across all days of spatial learning for swim time (p = .0001) and directional heading error (p = .03). Control animals exposed to sensory testing demonstrated significantly more efficient learning (p = .005) on swim days 2 and 3 versus control animals not exposed to sensory testing. CONCLUSIONS: Early and prolonged behavioral changes are evident following entorhinal cortex damage including sensory integration deficits and persistent spatial learning impairment.

Changes in directed attention and short-term memory in depression.

This study examined changes in directed attention and short-term memory in depression using a newly constructed battery of computerized measures. A repeated measures design was used with two sample groups; 25 individuals meeting DSM-IV criteria for Major Depression and a group-matched comparison sample of 27. Both groups were tested at three points in time over a 10-week period. Test-retest reliability of the measures was examined. Profile analysis demonstrated that there were differences between the depressed and comparison groups in both directed attention and short-term memory. Recommendations for specific improvements in the testing battery are discussed. The ability to detect changes in directed attention and short-term memory may have clinical utility in early detection of impending onset of depression or subtle residual symptoms of an acute episode that may impair functioning or signal a relapse.

Medial temporal lobe amnesia: a case study for nursing.

Maintaining and enhancing cognitive function is a crucial but challenging intervention for patients with memory problems. Research on the medial temporal lobe (MTL) memory system has yielded much information that can guide nurses in planning, evaluating, and performing effective interventions. A patient, Mrs. N, with a diagnosis of anaplastic astrocytoma of the left medial temporal lobe provides an example. Information from research guides assessment of Mrs. N and affords development of specific patient-centered interventions to maintain function, cope, and compensate. Data have been gathered from the patient, relatives, and caregivers to compare with and augment existing research, because few nursing case studies of amnesia involving patients with left medial temporal lobe tumors are available for analysis.

Minor brain injury: new insights for early nursing care.

More than a million people sustain a minor brain injury (MBI) annually. Recent research shows serious changes in cognitive ability are common consequences of such injuries, yet management of MBI sequelae receives little attention. Expanded assessment and treatment parameters are needed to capture and treat the subtle cognitive changes seen in this type of brain injury. Impaired directed attention (DA) is the most common problem after MBI. Individuals with compromised DA are distractible, impulsive, and often irritable. A new behavioral nursing model of MBI allows targeted assessment of distractibility, impulsivity, and irritability as aspects of impaired attention. The model also offers interventions to conserve or restore attention, which should prove helpful to both patients and practitioners.

Behavioral effects of transient cerebral ischemia.

CA1 neurons in the hippocampus, a brain structure involved in learning and memory, are selectively vulnerable to ischemic effects. In this study, the authors examined if duration of ischemia is directly related to extent of CA1 damage and degree of spatial learning deficit. Adult female Wistar rats received either 5-min or 10-min ischemia or sham surgery. Following recovery, rats were tested in the Morris water maze. Histological analysis showed moderate cell loss in CA1 (31%) and CA3 (12%) and minimal cell loss in CA2 (4%) with 5-min ischemia. Increased cell loss was seen in CA1 (68%), CA2 (16%), and CA3 (23%) with 10-min ischemia. Behavioral testing revealed that animals with 10-min ischemia have greater spatial learning deficits and they remain impaired across the test days compared to the 5-min ischemic group. Furthermore, degree of CA1 cell loss accounted for approximately 45% of the variance in spatial learning deficits in the ischemic group. The authors conclude that cell loss is largely confined to CA1 region in rats who received 5 and 10 min of ischemia and that increased ischemic duration results in persistent learning deficits in female rats; also, the degree of behavioral impairment is related to extent of CA1 cell loss.

Effects of environment on enhancing functional plasticity following cerebral ischemia.

Given the brain's capacity to recover from injury, plasticity may be enhanced following cerebral ischemia through environmental manipulation. Thus, the purpose of this study was to (1) determine the effects of early exposure to an enriched environment following ischemia on functional plasticity and (2) examine the relationship between morphological and behavioral plasticity. Adult female rats (n = 38) were divided into ischemia and control groups. Each group was further randomized to either standard (SC) or enriched conditions (EC). After 4 days of environmental exposure, rats were tested for 6 days in the water maze. Control and ischemia rats exposed to EC have increased total dendritic length (P < 0.05) as well as increased number of dendritic segments in the apical (P < 0.05) region of the hippocampal area compared to those housed in SC; furthermore, increased dendritic spine density in the apical (P < 0.05) region was also seen. Behavioral testing showed that ischemia rats exposed to SC have longer swim latencies (P < 0.05) and greater directional heading errors (P < 0.05) than ischemic rats exposed to EC; the latter group performed similar to controls. It is concluded that EC may be a potentially useful therapy in the recovery of spatial memory impairments seen after ischemia.

The effect of familiarity on distraction and single cue use after hippocampal damage.

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.

Aging and corticosterone injections affect spatial learning in Fischer-344 X Brown norway rats.

The hippocampus is one of the first brain structures to show age-related changes. Moreover, hippocampal neurons are endangered by prolonged exposure to high circulating levels of corticosterone with stress or aging. We examined the effects of aging and high corticosterone levels on spatial learning, a key hippocampal function. Young (4-6 months), old (23-25 months), and very old (31 months) male Fischer-344xBrown Norway (F-344xBN) rats received six pre-testing days in the Morris water task to determine baseline spatial learning performance. Next, half the animals in each group were given daily corticosterone injections for 15 days. During the last six injection days, all animals underwent post-testing in the Morris water task with the environment and goal location changed. Baseline, peak, and clearance plasma corticosterone levels were determined. During pre-testing, old animals swam as directly to the goal as the young, but very old animals were significantly impaired. During post-testing, both old and very old non-injected animals had significantly greater directional heading errors and flatter learning curves than the young. Among injected animals, the very old performed as well as the young, but the old did not. Old animals who did not show improvement during the first three pre-testing days were responsible for the old impairment during post-testing. Thus, only very old F-344xBN rats are impaired when initially exposed to a spatial learning task, but half the old and all very old animals are impaired when the environment is changed. Very old F-344xBN rats, however, demonstrate enhanced spatial learning when exposed to corticosterone injections.

Cue familiarity reduces spatial disorientation following hippocampal damage.

The purpose of this study was to determine whether familiarity with a cue would enhance the ability of rats with hippocampus (HPC) damage to locate a cued hidden platform in the Morris water test. After preoperative training with the cue (n = 21) or handling only (n = 17), rats were given electrolytic bilateral HPC lesions or sham surgery for controls. All rats were then tested for 4 days, 6 trials per day, with the cue marking the platform location. Rats with HPC lesions familiar with the cue (FB) were significantly more efficient than rats with HPC lesions unfamiliar with the cue (UB) in swim time (M = 10.31 +/- 2.2 vs 46.72 +/- 7.5 sec, p < .05) and in directional heading error (M = 31.98 +/- 3.4 vs 57.92 +/- 4.0 degrees, p < .05) on Day 1. These differences occurred across the 4 test days and were shown to be the result of an impairment in learning of the cue task in the UB groups rather than simply an effect of more practice with the cue by FB animals. No significant differences were found between FB animals and familial controls.

Effect of position on cardiovascular response during the Valsalva maneuver.

Sudden cardiac death (SCD) has frequently been associated with the Valsalva maneuver (VM), which is characterized by sudden intense changes in systolic blood pressure (SBP) and heart rate (HR). The purpose of this study was to examine the effect of manipulating body position on the intensity of SBP and HR changes during the VM. Thirty-two men and 32 women (35-55 years) without a history or signs of cardiovascular disease (CVD) were studied. Subjects produced a VM of 40 mmHg for 10 seconds in each of five randomly assigned bed (flat, sidelying, 30 degrees elevated, 70 degrees elevated) and chair positions. Age covaried with SBP and HR responses to the VM. When age relationships were factored out, the most intense changes in SBP during the VM occurred in the 30 degrees and 70 degrees elevated and chair positions. Persons with a history of atherosclerotic CVD, on bedrest, should be positioned with head of the bed flat to reduce cardiovascular risks associated with the VM.

Position modifies carotid artery blood flow velocity during straining.

The Valsalva maneuver (VM) produces rapid shifts in cerebrovascular blood flow and is often implicated in aneurysm rupture and rebleeding. To determine whether intensity of hemodynamic shifts is affected by position, we examined effects of five body positions (chair, 70 degrees and 30 degrees upright, flat, side) on carotid artery blood flow velocity (CABFV) across the VM in 141 healthy adults (30-55 yrs.). Subjects strained at 40 mmHg pressure for 10 seconds. CABFV was measured continuously by ultrasonic Doppler technique. During straining, position significantly (F = 13.7; p less than .0001) affected CABFV. Less reduction occurred in the chair (p less than .05) position than in any of the others. The 70 degrees position produced less fall in CABFV (p less than .05) than did the 30 degrees, flat and side positions. Less increase in CABFV across the VM was recorded in the chair position (p less than .05) than in any of the others. It is concluded that the chair position can be used therapeutically to reduce severe shifts of CABFV associated with straining.

Ethnic differences in physiological responses associated with the Valsalva maneuver.

Ethnic differences in cardiovascular indices at rest and across the Valsalva maneuver (VM) were studied in 30 Asian, 86 Caucasian, and 12 Black healthy men and women aged 30 to 55 years. Subjects simulated the VM by blowing into an aneroid pressure-gauge meter to 40 mmHg for 10 seconds. Resting systolic blood pressure (SBP) was significantly higher in Blacks than in Asians or Caucasians. During the strain phase of the VM, the fall in SBP from baseline was significantly greater in Asians and Blacks than in Caucasians. Further, Asians had the greatest overshoot of SBP above baseline. Although resting heart rate was significantly higher in Asians compared to Caucasians, there were no differences in heart rate responses to the VM. Reduction in carotid artery blood flow velocity during strain was significantly less in Blacks. We conclude that there are ethnic differences in cardiovascular indices at rest and across the VM.

Effects of age on autonomic cardiovascular responsiveness in healthy men and women.

Blood pressure and heart rate responses to the Valsalva maneuver (straining) were used to quantify the effects of age on autonomic cardiovascular responsiveness in 110 healthy men and women, 30 to 76 years. In general, aging was associated with diminished sympathetic responsiveness during strain. In women, however, the predominant age effect was a significant reduction in bradycardic response to systolic blood pressure overshoot following release of strain. When present, age-related differences in cardiovascular responses to the Valsalva maneuver were manifest by age 45. These findings are consistent with an age-related diminution of autonomic cardiovascular responsiveness in healthy adults. Moreover, they suggest that interventions to reduce the frequency and intensity of straining may be especially important in older adults in order to minimize health risks associated with rapid, abrupt changes in blood pressure.

Preexisting physical activity level and cardiovascular responses across the Valsalva maneuver.

To determine the effect of preexisting physical activity level on resting cardiovascular measures and the intensity of cardiovascular responses across the Valsalva Maneuver (VM), 131 young (30-55 years) and 67 older (greater than 55 years) healthy adults, classified into sedentary, active, semitrained, or trained groups, were studied. Resting heart rate (HR) was lower in all trained subjects. In contrast, resting diastolic blood pressure was lower in young but not older trained subjects. During the VM, the expected fall in systolic blood pressure (SBP) from baseline during strain was less in young trained but not older trained subjects. Physical training significantly lessened the intensity of SBP and HR responses during the overshoot phase of the VM only in young subjects, most often in young males.

The effects of hippocampal damage on adaptation to novelty in rats.

Nurses are the primary care givers of disoriented individuals. More knowledge of how wayfinding is accomplished could help improve care and determine nursing therapies. Humans and animals wayfind most efficiently by forming mental images called cognitive maps. It is theorized that the hippocampus (HPC) is necessary for generating and updating cognitive maps. Further, it is known that HPC damage alters wayfinding ability. This study is a secondary analysis of Therrien's data to investigate effects of HPC lesion side and animal gender on exploratory behavior when novelty is introduced into a familiar environment. After rats with HPC or sham lesions were trained on a place navigation task that involved learning to use a fixed set of distal cues to locate a platform submerged under water, novelty was introduced on two test days. Exploratory behaviors measured were swim distances in all areas of the tank, orientation directly beneath the distal cues, and directional turn following placement in the water.

Sustained remission of Cushing's disease with mitotane and pituitary irradiation.

Low doses of mitotane were given orally to 36 patients with Cushing's disease, concurrently with or after pituitary cobalt irradiation. Clinical and biochemical remission occurred in 29. The response to treatment occurred early in 17 patients and late in 12. The different pattern of response to mitotane was not related to the dose given or to its serum level. Early biochemical indicators of adrenal suppression with mitotane were a sharp decrease in adrenal response to the infusion of ACTH and in plasma levels of dehydroepiandrosterone sulfate. Although mitotane was given together with pituitary irradiation, initial remission was due mainly to the adrenal effect of mitotane. Plasma ACTH levels were still elevated when cortisol had returned to normal. In seventeen of the 29 patients who responded to treatment drug therapy has been discontinued, and they remain in remission of Cushing's syndrome. Side-effects have been dose dependent, with anorexia, nausea, decreased memory, and gynecomastia in men being the commonest.