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PubMed1999

EEG power changes during a multiple level memory retention task.

EEG changes related to the amount of information held in memory during a 4-s retention period were studied. The predictability of the amount of information held in memory was varied. In the weighted condition, 60% of the trials contained only one item and the remaining 40% of the trials were evenly distributed between trials containing 3, 5, 7, or 8 items. In the random condition, the levels were equally represented and randomly presented. In the blocked condition the levels were equally represented but presented in five blocks containing only items from one of the levels. Initial widespread decreases in alpha band power were followed by increased activity in all three conditions. The more difficult of the five levels produced decreased alpha activity in more localized posterior left hemisphere sites. This suggests two alpha mechanisms, one associated with task engagement and the other related to the cognitive demands regardless of the presentation context. Theta band power increased over frontal scalp, and to a lesser extent over left parietal and temporal areas and bilateral occipital sites, during only the weighted condition. These changes were uniform over the entire retention period. Beta 2 activity was also influenced by the task difficulty and the time course of the retention period in the two conditions. Beta 2 activity resembled both alpha and theta in that in levels 1, 2 and 3 it acted like alpha with increasing power over time at numerous widespread sites while the higher difficulty levels showed higher power at the beginning of the retention period and then decreased.

Adolescent↗
PubMed1983

CPR skills retention of lay basic rescuers.

In 1979-1980, 950 telephone company personnel were trained and tested at the basic rescuer level on recording manikins. In October 1981, a random group of 40 were retested without warning on the recording manikin. Skills retention was measured by comparing the tapes from training and retesting. Sixteen (40%) of those retested were able to perform effective ventilations and compressions of the manikin with 60% to 70% average retention compared to their training scores. The remaining 24 (60%) had ineffective ventilations or compressions or both. The two groups did not differ in the performance level achieved during training, or in the time interval between training and retesting. Eleven individuals retested at 13 to 14 months did not perform better than those retested later, suggesting the maximum skills deterioration had occurred within the first year. However, the effective performance group on the average were younger, and the majority had first aid training in addition to their CPR training. Only one had CPR retraining. This study supports the following recommendations: 1) lay basic rescuers should be retrained within the first year; 2) further studies of the factors influencing retention are advisable; 3) the younger age groups should be the first priority for citizen CPR training; and 4) because first aid training appears to improve CPR retention, training in both should be encouraged.

Adult↗
PubMed2000

Retentive and compressive strengths of modified zinc oxide-eugenol cements.

OBJECTIVES: This investigation sought to improve the handling and physical properties of a commonly used temporary zinc oxide-eugenol cement by changing the base/accelerator (B/A) ratio or combining it with a petroleum jelly or fluoride varnish. METHODS: Twelve modifications of a temporary cement were evaluated in terms of retentive strength, compressive strength at 24 h, film thickness and by scanning electron microscopy. RESULTS: Decreasing the B/A mixing ratio increased the retentive and compressive strengths, but reduced the film thickness of the cement. By increasing the percentage of incorporated petroleum jelly or fluoride varnish in the cement, there was a progressive decrease in the retentive and compressive strengths and in film thickness. CONCLUSIONS: Modifications of a zinc oxide-eugenol temporary cement to change the B/A ratio or to incorporate additives resulted in variations in physical properties. All modified forms of the cement had a film thickness less than 25 microns and a compressive strength below 35 MPa. With a wide range of retentive strength, modified forms of zinc oxide-eugenol cement may be found to have diverse clinical applications.

Analysis of Variance↗
PubMed2003

Transurethral microwave thermotherapy (TUMT) with the Targis System: a single-centre study on 78 patients with acute urinary retention and poor general health.

OBJECTIVES: To evaluate the Targis System in men presenting with acute urinary retention, high prostate volume and high operative risk. MATERIALS AND METHODS: Between August 1997 and March 2001, a total of 78 patients in poor general health status presenting with large prostate glands and acute urinary retention secondary to BPH were treated with the Targis TUMT device. Mean age, mean prostate volume, and the percentage of patients who were able to urinate spontaneously after the procedure as well as mean peak and average flow rates and mean residual urine volume were evaluated. RESULTS: 68 (87.1%) of the 78 patients were able to urinate spontaneously three months after the procedure. In 5 (7.3%) of the 68 patients urinary retention recurred within two years. Following treatment, the mean peak flow rate in the 68 successfully treated patients was 11.1 ml/s, while the mean postvoid residual volume was 46 ml. CONCLUSION: Based on these data we recommend transurethral thermotherapy using the Targis System for patients in poor general health presenting with urinary retention and prostate volumes of more than 35 cc in whom TURP is not possible.

Aged↗
PubMed2004

Exposure to retrieval cues improves retention performance and induces changes in ACTH and corticosterone release.

Memory retrieval can be facilitated by pretest exposure to cues associated with the original training. The present series of experiments was aimed at investigating whether the effectiveness of the retrieval cues might be due to their emotional value and thus be associated to a particular pattern of activation of stress systems. Therefore, the effects of exposing rats to different cueing conditions were investigated both on retention performance and on the level of different stress hormones (ACTH, corticosterone and glucose; the latter as an indirect index of adrenergic/sympathetic nervous system activation). Rats trained in a brightness avoidance discrimination task exhibited an enhancement of the retention performance following exposure to the light discriminative stimulus when delivered 1-day after training and not after 21 days, while exposure to contextual cues led to opposite effects on the retention performance, confirming our previous results. Analyses of the level of stress hormones at the time of testing indicated that when the retrieval cues were effective at the behavioral level, cued rats exhibited higher ACTH plasmatic levels than controls, but did not differ in their glucose or corticosterone levels. Further experiments showed that one day after training, both ACTH and corticosterone levels were elevated in light-cued rats if hormone samples were taken 15 min after cueing. These results show that exposure to an effective retrieval cue is accompanied by the activation of the hypothalamus-pituitary-adrenal axis. The possible involvement of the Corticotropin Releasing Factor at the level of the hypothalamus and amygdala (particularly the central nucleus) on the facilitating effect on retention performance following exposure to aversive training-associated cues is discussed. The present results strengthen the notion that emotion can interact with retrieval processes.

Adrenocorticotropic Hormone↗
PubMed2000

Factors predicting for postimplantation urinary retention after permanent prostate brachytherapy.

PURPOSE: Urinary retention requiring catheterization is a known complication among prostate cancer patients treated with permanent interstitial radioactive seed implantation. However, the factors associated with this complication are not well known. This study was conducted to determine these factors. METHODS AND MATERIALS: Ninety-one consecutive prostate cancer patients treated with permanent interstitial implantation at our institution from 1996 to 1999 were evaluated. All patients underwent pre-implant ultrasound and postimplant CT volume studies. Isotopes used were (125)I (54 patients) or (103)Pd (37 patients). Twenty-three patients were treated with a combination of 45 Gy of external beam radiation therapy as well as seed implantation, of which only 3 patients were treated with (125)I. Mean pretreatment prostate ultrasound volume was 35.4 cc (range, 10.0-70.2 cc). The mean planning ultrasound target volume (PUTV) was 39.6 cc (range, 16.1-74.5 cc), whereas the mean posttreatment CT target volume was 55.0 cc (range, 20.2-116 cc). Patient records were reviewed to determine which patients required urinary catheterization for relief of urinary obstruction. The following factors were analyzed as predictors for urinary retention: clinical stage; Gleason score; prostate-specific antigen; external beam radiation therapy; hormone therapy; pre-implant urinary symptoms (asymptomatic/nocturia x 1 vs. more significant urinary symptoms); pretreatment ultrasound prostate volume; PUTV; PUTV within the 125%, 150%, 200%, 250%, 300% isodose lines; postimplant CT volume within the 125%, 150%, 200%, 250%, 300% isodose lines; D90; D80; D50; ratio of post-CT volume to the PUTV; the absolute change in volume between the CT volume and PUTV; number of needles used; activity per seed; and the total activity of the implant. Statistical analyses using logistic regression and chi2 were performed. RESULTS: Eleven of 91 (12%) became obstructed. Significant factors predicting for urinary retention were the total number of needles used (p < 0.038); the pretreatment ultrasound prostate volume (p < 0.048); the PUTV (p < 0.02); and the posttreatment CT volume (p < 0.021). Two of 51 patients (3.9%) requiring 33 or fewer needles (median) experienced obstruction vs. 9 of 40 (22.5%) requiring more than 33 (p < 0.007). If the pretreatment ultrasound prostate volume was 35 cc or less (median), 3 of 43 (7%) vs. 8 of 36 (22%) with a volume greater than 35 cc experienced obstruction (p < 0.051). CONCLUSION: The number of needles required (perhaps related to trauma to the prostate) and the prostate volumes were significant factors predicting for urinary retention after permanent prostate seed implantation.

Brachytherapy↗
PubMed2000

Differential effects of parafascicular electrical stimulation on active avoidance depending on the retention time, in rats.

To evaluate whether electrical stimulation of the parafascicular nucleus of the thalamus can improve short-term (24 h) and/or long-term (11 days) retention of two-way active avoidance, rats were implanted with an electrode at this nucleus (experimental groups with stimulation in the parafascicular, and control groups without stimulation) or above it (other control groups without stimulation). After a single 30-trial acquisition session, experimental groups were submitted to a 20-min session of electrical stimulation. Results showed that parafascicular stimulation improved the 24-h retention of the task (number of avoidances made), increasing also the percentage of subjects that achieved a learning criterion and reducing the number of trials needed to reach it. In contrast, no differences among groups were found on the 11-day retention test. The present results agree with previous data showing a short-term effect of parafascicular stimulation on retention, and confirm its involvement in learning and memory modulation. These data are discussed in the context of the acceleration and strengthening of the memory by activation of arousal systems, and/or specific cortical-striatal systems.

Analysis of Variance↗
PubMed2002

Participation and retention in drug abuse treatment services research.

We examined potential bias in treatment effectiveness research by studying client characteristics associated with initial participation and subsequent retention in research assessments among clients in substance abuse treatment receiving case management. Six hundred thirty-four residential and 429 outpatient clients were invited to participate. Participants were randomly assigned to one of four conditions. Logistic regression examined the relation between client characteristics and initial participation and retention in follow-up assessments. Females and clients with significant others were more likely to participate and remain in the study. Older persons and criminal justice-referred clients were less likely to participate. Older clients and urban outpatient clients were more likely, and criminal justice-referred clients were less likely, to be retained. Two case management conditions were associated with decreased retention. Client characteristics are important factors in participation and retention in treatment services research. Further, client characteristics may bias estimates of effectiveness generally, or for specific populations.

Case Management↗
PubMed2003

Celecoxib to decrease urinary retention associated with prostate brachytherapy.

PURPOSE: To retrospectively evaluate the effect of celecoxib in preventing urinary retention following prostate brachytherapy. MATERIALS AND METHODS: Between December 1997 and November 2001, 149 patients underwent a prostate implant. Medical records were reviewed to identify those who had acute urinary retention after the procedure. Urinary retention was scored based on replacement of the urinary catheter and the number of calls to the clinic and/or unscheduled clinic visits within 1 month after the implant. RESULTS: The use of celecoxib was associated with a decreased need for replacement of the catheter (p=.04) and decreased number of calls to the clinic and/or unscheduled clinic visits (p=.002). No patient who was given celecoxib for 1 week before brachytherapy required a urinary catheter compared to 14 (of 120) who did not receive celecoxib. CONCLUSIONS: The use of celecoxib appears to result in decreased urinary retention following prostate brachytherapy.

Aged↗
PubMed1999

The implant neck: smooth or provided with retention elements. A biomechanical approach.

A combined three-dimensional and axisymmetric finite element analysis was made of the effect upon the peak interfacial shear stress of providing an axially loaded mandibular dental implant with retention elements all the way up to the crest of the implant as opposed to a smooth neck. The effect of increased wall thickness of the implant and of using bi-cortical fixation as opposed to uni-cortical fixation was also studied. Retention elements at the implant neck were found to bring about a major decrease in the peak interfacial shear stress. Increased wall thickness and bi-cortical fixation also resulted in decreased peak interfacial shear stress but this effect was minor. The interpretation of this was that all these three measures increase the capacity of the implant to carry axial loads. Thus from a biomechanical viewpoint it appears to be advantageous to provide the neck of screw-shaped implants with retention elements, for example a rough surface of suitable micro-architecture and/or a micro-thread. It is furthermore suggested that retention elements at the implant neck will counteract marginal bone resorption in accordance with Wolff's law. This paper is a revision of: Hansson, S. (1997) Some steps to improve the capacity of dental implants to resist axial loads. In: Hansson, S., ed. Towards an optimized dental implant and implant bridge design: A biomechanical approach. Thesis. Göteborg: Chalmers University of Technology.

Alveolar Process↗
PubMed2002

Comparative evaluation of casting retention using the ITI solid abutment with six cements.

OBJECTIVE: The purpose of this study was to test the retention of metal copings fabricated to fit on the one-groove, one flat-sided solid titanium abutment using six different cements. MATERIALS AND METHODS: Ten hollow screw 3.8 mm ITI implants were mounted in acrylic resin blocks. A solid titanium abutment was placed on each implant and torqued at 35 Ncm. Prefabricated burn-out caps were placed on the titanium abutment and wax loops added to the occlusal surface to allow for subsequent retention testing. All plastic caps were embedded in phosphate-bonded investment and cast with noble alloy. Castings were inspected for surface irregularities using a stereomicroscope at 10x magnification. The six cements were: 1) eugenol-free zinc oxide (Temp Bond NE); 2) zinc-oxide eugenol (IRM); 3) zinc phosphate (Hy-Bond); 4) resin-modified glass ionomer (Protec Cem); 5) zinc polycarboxylate (Durelon) and 6) 10-methacryloyloxydecyl dihydrogen phosphate resin (Panavia 21). After cementation, implant-abutment-casting assemblies were stored for 24 h in 100% humidity. Samples were subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 0.5 mm/min. The load required to de-cement each coping was recorded and mean values for each group calculated. Means and standard deviations of loads at failure were analyzed using ANOVA and a Tukey studentized test. Statistical significance was set at P < or = 0.05. RESULTS: The mean values (+/- SD) of loads in kilograms at failure (n = 10) for the various cements were as follows: Temp Bond 3.18 (+/- 1.1) (Tukey group D), IRM 9.25 (+/- 3.83) (Tukey group CD), HY-Bond 10.9 (+/- 6.52) (Tukey group C), Protec Cem 18.98 (+/- 6.23) (Tukey group B), Durelon 23.55 (+/- 4.29) (Tukey group B) and Panavia 21, 36.53 (+/- 8.1) (Tukey group A). Means with the same letter in the Tukey grouping are not significantly different. CONCLUSIONS: The retention values of castings cemented to ITI solid abutments have not been reported in the literature. Within the limitations of this in vitro study, the results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements in their ability to retain the castings. This ranking is somehow different than that obtained when the same cements are used on natural teeth. The material and surface characteristics of the implant abutment are likely responsible for this difference. Cement retention values obtained from studies that use teeth as abutments may be misleading when used in cement-retained implant-supported crowns. It is at the clinician's discretion to use a certain type of cement, based on the situation at hand.

Analysis of Variance↗
PubMed1986

Factors modulating the effects of teleost telencephalon ablation on retention, relearning, and extinction of instrumental avoidance behavior.

Two experiments on the nature of avoidance behavior in the goldfish are reported. In the first experiment, a master/yoked design was used to determine the degree to which Pavlovian conditioning would generate acquisition of a shuttle response by goldfish. Results indicated that the mere sequence of signal-shock pairings experienced by the avoidance animals is not in this situation sufficient to explain the development of the instrumental avoidance responding. The second experiment was conducted to study the effects of three variables on the retention and extinction of the avoidance response. First, unilateral lesions of the telencephalon produced a transient deficit from which the subjects recovered to normal levels. Retention of the avoidance response after bilateral telencephalon ablation was impaired and never fully recovered with additional training. Second, this deficit was reduced under higher intensities of electric shock. Third, overtraining on the task before the ablation had only a nonsignificant enhancing effect on retention levels. Extinction was always poorer following ablation, independent of the type of ablation, intensity of shock, degree of overtraining, and terminal retention level of performance. The results are discussed in terms of various theories of telencephalic function in fish.

Animals↗
PubMed1987

Lesions of the middle cerebellar peduncle disrupt acquisition and retention of the rabbit's classically conditioned nictitating membrane response.

Rabbits were classically conditioned to emit a nictitating membrane response (NMR) to either a light or tone conditioned stimulus (CS) paired with an eye shock unconditioned stimulus (UCS). They then received lesions of the middle cerebellar peduncle (MCP) or served as unoperated controls. Following surgery, they were given separate presentations of tone, light, and vibratory CSs, each paired with the eye shock UCS. In this way, conditioned responses (CR) to the previously trained light or tone served as a test of retention, whereas CRs to the remaining two conditioned stimuli (tone and vibratory or light and vibratory) served as a test of acquisition. The results of the study revealed that rabbits with complete lesions of the MCP showed disrupted acquisition and retention of the conditioned NMR to all stimuli, rabbits with partial MCP lesions also showed disrupted acquisition and retention to all CSs, but to a lesser degree, and animals with lesions that missed the MCP and unoperated controls both showed normal acquisition and retention of the conditioned NMR. These data are consistent with the view that the cerebellum is an essential part of the circuit for classical conditioning of the NM response and that information about CSs in the auditory, visual, and tactile modalities reach the cerebellum by way of the MCP.

Afferent Pathways↗
PubMed1989

Inhibition by diazepam of the effect of additional training and of extinction on the retention of shuttle avoidance behavior in rats.

Rats were submitted to a training and a test session in a shuttle avoidance task. In some groups, a second training session was interpolated 2 or 24 hr after the first session. In others, a session of extinction was interpolated 2 or 24 hr after the training session. When the interpolated task was 2 hr after training, training-test interval was 24 hr. When the interpolated task was 24 hr after training, training-test interval was 48 hr. The additional training enhanced, and the extinction depressed, retention test performance. Diazepam, given 30 min prior to the first (or only) training session enhanced the performance of avoidance responses in that session but inhibited it in the subsequent retention test. Diazepam given 90 min after training had no effect on retention. Diazepam given 30 min prior to either the additional training session or the extinction session did not affect performance in that session but cancelled their effects on retention test performance. The effects are related to the previously described prevention by diazepam of interfering effects on memory.

Animals↗
PubMed1989

Age-related differences in the impact of spacing, lag, and retention interval.

An experiment is reported that examines age-related differences in the lag effect and its relation to retention interval. A total of 30 young and 30 older adults received both once-presented pairs and twice-presented pairs that were tested in a continuous cued-recall paradigm either after a short retention interval (2 pairs intervening between the last presentation of a pair and its test) or a long retention interval (20 pairs intervening between the last presentation of a pair and its test). In addition, the twice-presented pairs were separated by either 0, 1, 4, 8, or 20 intervening pairs. The results replicated the interaction between retention interval and lag that has been reported by Glenberg (1976, Journal of Verbal Learning and Verbal Behavior, 15, 1-16). Furthermore, although the older adults performed considerably lower than the younger adults in overall recall performance, their data were remarkably similar to the younger adults in the patterning of means. A mathematical modeling procedure was used to fit the data to Estes' stimulus fluctuation model. The results of this modeling procedure suggest that, compared with younger adults, older adults (a) encode less contextual information at a given point in time and (b) have a slower rate of contextual fluctuation across time.

Adult↗
PubMed1977

Effects of reserpine on retention of escape reversal in mice: absence of state-dependent learning.

A discriminated escape training paradigm was used to study the effects of reserpine on learning and memory in mice. Intraperitoneal injection of reserpine before reversal training had no effect on acquisition but did produced a time-and dose-dependent impairment of retention test performance 10 days later. These results suggested that reserpine may have interfered with some aspect of memory storage. Retention impairments observed when a 2.0 mg/kg reserpine injection was given 2 hr before reversal training were not attenuated by readministering the drug before testing, a finding that provides no support for a state-dependency interpretation. Furthermore, animals treated with reserpine exhibited inferior retention of previous training, regardless of the pharmacological state present during that learning. This was interpreted as a drug-induced impairment of memory retrieval. In addition, performance during the initial discriminated escape training session suggested that reserpine may also impair acquisition under some conditions. In the last experiment, it was found that when the catecholamine precursor L-dihydroxyphenylalamine (100 mg/kg) and the indole amine precursor D,L-5-hydroxytryptophan (125 mg/kg) were both given after reserpine treatment, subsequent retention performance was not significantly impaired. The results are discussed in terms of the possible roles of biogenic amines in arousal, learning, and memory.

5-Hydroxytryptophan↗
PubMed1979

Reduction of ontogenetic retention decrements in rats by pretraining stressful experiences.

Pretraining stressful experiences, either similar to or qualitatively different from the conditioning unconditioned stimulus, reduced ontogenetic retention decrements without directly influencing response acquisition. Rats that received pretreatment with footshock, hypthermia, or restraint on Days 16, 17, and 18 of age showed substantially improved long-term retention of conditioned fear learned at 20 days of age. It was also found that preshock enhanced retention of both an appetitive approach response and punishment of the approach response. Several experiments involving extinction and undertraining manipulations indicated that the facilitation of retention was not directly attributable to acquisition strength.

Animals↗
PubMed1981

Daily biorhythmicity influences, homing behavior, psychopharmacological responsiveness, learning, and retention of suckling rats.

A total of 385 suckling rats were used to investigate the effects of 24-hr biorhythmicity on performance. Nest seeking (homing) in 7-day-old pups and its facilitation by d-amphetamine varied across time of day. Analysis of initial choice revealed that the pups' ability to detect and position themselves in the direction of the nest did not vary across time of day. Homing behavior was not an artifact of random activity level but was related to the pups' motor performance which varied with a daily rhythm. Circadian rhythmic influences on the acquisition and retention of an amphetamine-induced odor aversion were shown by manipulating time of day of conditioning and subsequent retention testing. The time of day effect on conditioning was attributed, in part, to daily rhythmic changes in the effectiveness of the unconditional stimulus. Retention was optimal in pups tested at the time of day corresponding to that of their original training. Time of day may serve as a contextual stimulus that is important for retention in immature as well as adult animals. An appreciation of these 24-hr rhythms is warranted for an accurate assessment of the behavioral competence of developing animals.

Animals↗