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PubMed2001

Effects of grade retention on academic performance and behavioral development.

This study examined the controversial practice of grade retention and children's academic and behavioral adjustment using data from the Quebec Longitudinal Study of Kindergarten Children. We employed an autoregressive modeling technique to detect the impact of being held back during primary school on subsequent academic performance and behavioral development until age 12 years. The results indicate both a short- and long-term negative influence on academic performance for boys and girls. Children's anxious, inattentive, and disruptive behaviors persisted and, in some cases, worsened after grade retention. These prospective associations were long lasting and more pronounced when grade retention occurred early in primary school. Boys were more vulnerable to the negative influence of grade retention on academic performance and classroom disruptiveness. Disruptive behavior in girls was comparatively less associated with long-term consequences than boys. Nevertheless, girls experienced both short- and long-term academic performance problems in the aftermath of grade retention. Children's prosocial behavior appeared unaffected by grade retention. These results are independent of what would have been expected by the natural course of academic and behavioral development.

Achievement↗
PubMed1990

Acquisition and retention of a letter-detection skill.

In two experiments, we examined the acquisition and retention of a letter-detection skill with a consistent-mapping procedure. In Experiment 1, subjects were trained from 0 to 4 sessions at detecting the letter H in displays containing random letters, and retesting occurred after a 1-month delay. Performance improved and in some cases became more automatic, and the performance level was maintained over the retention interval. When tested with a prose passage, the high error rate on the word THE was eliminated after training and after the retention interval, regardless of the amount of training. In Experiment 2, two subjects were given 12 sessions of training followed by a retention test 6 months later. For 1 subject there was also a retention test 15 months after acquisition. Performance improved dramatically with training, and substantial but not complete automaticity was achieved. Performance on the retention tests was close to the final acquisition level. The surprising lack of forgetting in this study was contrasted with the substantial forgetting typically found in studies of verbal learning.

Form Perception↗
PubMed1978

Effects of posttraining injection of cholinergic agonists and antagonists into the amygdala on retention of passive avoidance training in rats.

Rats were given a single footshock while licking a water tube and tested 24 hr later for retention of the footshock experience. A single bilateral injection of a subseizure dose of physostigmine into the amygdala applied immediately, but not 18 hr, after the footshock imparied retention. This effect appeared to be somewhat localized, as physostigmine injected into the hippocampus or lateral ventricles did not disrupt retention. Conversely, a subseizure dose of atropine sulfate into the amygdala, given immediately or 18 hr after the footshock did not impair retention. Atropine injected concurrently with physostigmine into the same amygdaloid loci counteracted a potential physostigmine-induced retention deficit. Injection of carbachol into the amygdala also impaired retention; however, carbachol precipitated seizures and possibly exerted proactive consequences on performance. The time-dependent nature of the deficit following physostigmine is consistent with the view that injection of cholinergic agonists into the amygdala disrupts memory for the footshock experience.

Amygdala↗
PubMed1982

Acquisition and extended retention of a conditioned taste aversion in preweanling rats.

The time course of memory decay for infant rats may shed light on the processes responsible for infantile amnesia. A taste aversion conditioning procedure appropriate for both neonatal and adult rats was employed in four experiments to investigate the ontogeny of extended retention. In Experiment 1, rats trained at 1, 10, 20, or 60 days of age were tested for retention of the taste aversion 25 days later. At testing, only those rats conditioned when 20 or 60 days old demonstrated significant taste aversions. Experiments 2 and 3 established that rats 14-15 days old and older were able to retain significant taste aversions following a 25-day retention interval. Younger rats did, however, acquire and retain the aversion for several days and showed a gradual retention loss over progressively longer retention intervals (Experiment 4). These findings suggest that preweanling rats demonstrate initial consolidation, storage, and retrieval of conditioned taste aversions. It is only after this initial period that retention deficits become evident.

Aging↗
PubMed2003

Retention and postinsertion maintenance of bar-clip, ball and magnet attachments in mandibular implant overdenture treatment: an in vivo comparison after 3 months of function.

It could be hypothesised that attachments, which provide more retention against vertical and horizontal dislodgement, will be associated with more favourable parameters of oral function. This in vivo study is designed to provide data regarding initial retention force, loss of retention force after 3 months of function and postinsertion maintenance and complications associated with the use of magnet, bar-clip and ball attachments in mandibular overdenture treatment. Eighteen edentulous subjects received two permucosal implants in the inter-foramina region of the mandible, a new denture and three successive suprastructure modalities (magnet-, bar-clip and ball attachments). The retention force of the attachments at baseline and after 3 months was measured in a standardised way. The amount and type of postinsertion maintenance that was related to the attachment were evaluated. No differences in retention force at baseline and after 3 months of loading were observed for all three attachment types. The mean retention forces of magnet attachments, bar-clip attachments and ball attachments were 8.1, 31.3 and 29.7 N respectively. Functional maintenance complications related to the attachments were predominantly observed in 11/36 magnet attachments. Functional problems in the ball attachment group were relatively rare, easily manageable and seen in 4/36 attachments. The bar-clip attachments exhibited no maintenance problems at all.

Adult↗
PubMed1999

Comparison of the retentive and photoelastic properties of two prefabricated endodontic post systems.

This in vitro study compared the retention and photoelastic stress patterns from two loading conditions, vertical (133.2 N, 30 pounds) and oblique at a 26 degrees angle (133.2 N, 30 pounds) for two prefabricated post systems. The post studied were: (1) Flexi-Post (a split-shank threaded post) and (2) C-Post (a carbon fibre bound in an epoxy resin, passive double taper tier post). Two groups with 10 specimens per group were subjected to retentive forces with a universal testing machine (MTS 810 Material Testing Machine). In addition, two photoelastic test blocks were prepared with simulated root canals for each post studied. After cementation the photoelastic blocks were photographed before vertical and oblique loading and after loading. One-way analysis of variance (ANOVA) for retention data revealed a highly significant difference (P<0.0001) between groups. The Flexi-Post had a statistically higher mean retention force of 1180.6 N (265.9 pounds), while the C-Post had a mean of 171.8 N (38.7 pounds). Photoelastic analysis indicated minimal stresses for both the Flexi-Post and C-Post in the unloaded state. The C-Post showed asymmetrical apically stress patterns, while loaded in both states. The multi-tiered system of the Flexi-Post clearly distributes stress symmetrically, while the C-Post distributes stresses asymmetrically. The symmetric, even stresses and statistically higher retentive strength for Flexi-Post are more favourable than the asymmetric, uneven stresses and relatively low retentive strength for the C-Post.

Analysis of Variance↗
PubMed2003

In vitro retention force changes of prefabricated attachments for overdentures.

Changes in the retention force of six prefabricated spherical and cylindrical attachments were examined in vitro under continuous loading. The testing machine permitted insertion-separation cycles to be tested under reproducible conditions while a calibrated measuring device determined the insertion and retention forces. At the beginning, during the so-called run-in period, all anchoring elements showed a very unstable behaviour characterized by a varying marked increase and subsequent decrease in the retention force. During the ensuing functional period, the retention force followed a more stable course. In this phase, the frictional attachments having lamellae for activation proved more stable than did the spring-loaded retention attachments. Furthermore, in two of five cylindrical anchors by Gerber, the spring broke. This provides support to the concept that prefabricated attachments should be constructed as robust elements composed of as few individual parts as possible. This would help to ensure that service and repairs remain at a minimum. Frictional attachments with lamellae for activation are to be preferred for use in matrices and patrices over attachments having spring-loaded retention.

Dental Prosthesis Retention↗
PubMed2000

Incidence and outcome of poststroke urinary retention: a prospective study.

OBJECTIVE: To document the incidence and outcome of poststroke urinary retention, and to determine clinical variables associated with it. DESIGN: Cohort of 80 consecutive patients. SETTING: Inpatient setting of a tertiary rehabilitation center. PARTICIPANTS: Eighty patients (48 men, 32 women; mean age, 65.4 yr) with a first ischemic stroke, admitted for rehabilitation within 4 weeks of the stroke. MAIN OUTCOME MEASURES: Patients had their postvoid residuals (PVR) assessed via a bladder scanner within 72 hours of admission. Urinary retention was defined by a PVR of more than 100mL on 2 consecutive occasions. RESULTS: Urinary retention was present in 23 (29%) patients. Cognitive impairment, aphasia, diabetes mellitus, and cortical stroke were present in 30%, 29%, 31%, and 41% of patients, respectively. Fifteen (19%) patients developed urinary tract infection during rehabilitation. Urinary retention was significantly associated (p < .05) with cognitive impairment, diabetes mellitus, aphasia, a lower admission functional status (as measured on the modified Barthel index), and urinary tract infection, but not with the use of anticholinergic medications. On discharge, 4 patients still had urinary retention (3 were voiding spontaneously and the other used intermittent catheterization). CONCLUSION: Urinary retention was common in patients with ischemic stroke. It should be strongly suspected in patients with aphasia, cognitive impairment, poor functional status, and diabetes mellitus.

Age Distribution↗
PubMed2002

The effects of augmented sensory feedback precision on the acquisition and retention of a simulated chiropractic task.

OBJECTIVE: To examine the effectiveness of knowledge of results precision in the acquisition and retention of a simulated manipulative procedure. DESIGN: A controlled trial was conducted, with subjects assigned to 1 of 2 interventions by means of a stratified random technique. METHODS: Seventy-one healthy male and female chiropractic student volunteers were asked to control the application of force of a simulated chiropractic manipulative procedure. Two feedback conditions (quantitative and qualitative), 2 performance conditions (light and heavy force levels), and 3 delay intervals (1, 5, and 8 days) were studied. Acquisition trials were divided into 10 blocks of 5 trials for a total of 50 trials. All subjects performed 2 blocks of 10 trials (total of 20 trials) during the no-feedback retention phase. Absolute constant error (/CE/) was analyzed as the measure of performance accuracy, and variable error (VE) was used to determine performance consistency. RESULTS: No significant main effect for the 2 feedback groups was found for /CE/ and VE during the acquisition phase. A significant main effect for force was found for /CE/ and VE, indicating that subjects were more accurate during light conditions than heavy conditions. There was a significant main effect for trial blocks for both /CE/ and VE, indicating that groups became more accurate and consistent as a result of practice. During the retention phase, a significant main effect for retention group conditions was identified for /CE/ but not for VE. This indicates that the retention groups differed in accuracy but were similar in consistency. Post hoc analyses indicated that subjects were less accurate as time between acquisition and retention trials increased. There was a significant main effect for trial blocks for VE but not for /CE/, suggesting that groups became more consistent between trial blocks. A significant group trial block interaction was revealed for /CE/. No other main effects or interactions in the analyses were significant for /CE/ or VE. CONCLUSION: The findings of this study suggest that practice sessions with kinetic devices (simulators) and performance feedback, whether quantitative or qualitative, may be useful when implemented to assist the performance of complex motor skills. There is not enough evidence to support the idea that the training used in this study could generate lasting learning effects.

Adult↗
PubMed1991

Composition of practice: influence on the retention of motor skills.

The purpose of these experiments was to investigate further the variable practice effect found by Shea and Kohl (1990). Experiment 1 was an initial attempt to determine the locus of the retention benefits demonstrated by subjects provided variable practice experiences. All groups received 20 acquisition blocks consisting of five test trials per block at a target of 150 N. The interval between test trials was either unfilled or filled, with additional trials consisting of the same target force, variable target forces, or practice on an unrelated motor task. The results indicated retention was not incremented (relative to an unfilled interval) by requiring subjects to perform an unrelated motor task in the intertest-trial interval. However, when the interest-trial interval was filled with practice on related motor tasks, retention was significantly improved. Experiment 2 assessed the impact of increasing the number of related motor tasks interpolated between test trials. The results indicated filling the intertest-trial interval with one motor task resulted in large retention benefits relative to an unfilled interval. Further increases in the number of related motor tasks (3) interpolated between test trials resulted in only modest increments to retention. The results were consistent with the elaboration perspective proposed by Shea and Zimny (1983). The elaboration perspective proposes that the simultaneous presence of related items in working memory facilitates interitem elaborative and distinctive processing that ultimately results in retention benefits.

Adult↗
PubMed1996

A prospective study of urinary retention and risk of death after proximal femoral fracture.

Older age, dementia syndrome and impaired mobility are well recognized risk factors for fatality after fracture of the proximal femur. Urinary retention is recognized as a common complication of elective total hip replacement. In this investigation, we estimated the incidence of urinary retention associated with hip fracture in older women and assessed its relationship to 2-year post-operative fatality. Over a 7-month period, 309 women aged 65 and over were admitted to one trauma unit with hip fracture. Readings of post-voiding residual volume were taken on admission (pre-operative), within 24 hours of operation (post-operative) and 5-7 days post-operatively (recovery). Of the 309 patients, 244 (79%) had readings of post-voiding residual volume taken on admission; 90/244 (37%) had retention pre-operatively, 122/216 (56%) post-operatively and 40/183 (22%) in the recovery phase. One year after operation 305 patients were traced and median follow-up was 2 years. Older age, cognitive impairment, polypharmacy, impaired mobility and urinary retention on admission and during recovery were associated with a higher fatality in the first post-operative year. Pre-operative urinary retention is common among older women with proximal femoral fracture and affects over half post-operatively. Retention is one of several factors associated with higher fatality.

Aged↗
PubMed2003

Interstitial laser coagulation of the prostate for management of acute urinary retention.

PURPOSE: We evaluated the clinical efficacy and benefit of interstitial laser coagulation of the prostate (ILCP) in patients with benign prostatic hyperplasia (BPH) presenting with acute urinary retention. MATERIALS AND METHODS: Patients presenting with acute urinary retention were prospectively evaluated. Patients underwent ILCP and outcomes were evaluated by post-void residual urine, maximum flow rate, International Prostate Symptom Score, and disease specific quality of life score at baseline, 1, 3, 6 and 12 months. RESULTS: A total of 85 patients were enrolled in the study and 53 were diagnosed with acute urinary retention secondary to BPH. A total of 33 were not catheter-free after a week and 28 of them agreed to undergo ILCP. Mean preoperative prostate volume was 54.6 ml (range 23.0 to 130.0) and mean residual volume presenting with retention was 602 ml (range 200 to 1,150). There were no intraoperative or postoperative adverse events except urinary infection in 2 patients. Mean catheterization duration was 6.3 days (range 3 to 18) and all patients became catheter-free postoperatively. Mean followup was 16.9 months (range 7 to 31). Mean maximum flow rate (+/-SD) was 11.2 ml per second (+/-5.7) 3 months after treatment. Mean International Prostate Symptom Score and quality of life scores decreased from 23.1 (+/-6.4) at baseline to 8.0 (+/-5.3) at 3 months (p <0.001), and 5.0 (+/-1.2) to 1.9 (+/-1.6, p <0.001), respectively. Mean estimated prostate volume decreased by 19.4% (54.6 to 44.0 ml) 6 months postoperatively (p <0.001). Only 2 patients had recurrent urinary retention during followup. CONCLUSIONS: Our study suggested that ILCP is a safe and effective therapy for patients with BPH presenting with acute urinary retention.

Acute Disease↗
PubMed2005

Structural assessment of the urethral sphincter in women with urinary retention.

PURPOSE: The pathophysiology of urinary retention in women is generally unknown but a subgroup of women with urinary retention have been diagnosed as having so-called primary disorder of sphincter relaxation on the basis of an abnormal urethral sphincter electromyogram. It was suggested this sphincter overactivity could lead to work hypertrophy of the urethral rhabdosphincter and in this study we looked for any evidence of such muscle fiber hypertrophy. MATERIALS AND METHODS: In 9 women 18 to 45 years old (mean age 31.6) with urinary retention and overactive urethral sphincter electromyogram, light and electron microscopy were used to examine core needle biopsies of the urethral rhabdosphincter taken under transvaginal ultrasound control. Of the 9 patients only 5 biopsies processed for light microscopy and 4 processed for electron microscopy contained striated urethral muscle fibers. The results of these biopsies were compared to the morphology of a control specimen from a postmenopausal woman without a history of urinary retention. RESULTS: On light microscopy the urethral rhabdosphincter fiber diameter did not differ among patients (mean average 7.6 mum), was less than that reported in the literature (15 to 20), but did not differ from that of the control (mean 9.9). In all patients electron microscopy showed excessive peripheral sarcoplasm with lipid and glycogen deposition, and sarcoplasmic accumulation of normal mitochondria. These ultrastructural abnormalities were not seen in the control. CONCLUSIONS: To our knowledge this is the first morphological description of the urethral rhabdosphincter in a subgroup of women with urinary retention. Mean rhabdosphincter fiber diameter was approximately the same in patients and controls. This study does not support the previous theory that urethral sphincter overactivity in a subgroup of women with urinary retention leads to work hyperplasia of urethral rhabdosphincter fibers. An alternative hypothesis is suggested.

Adolescent↗
PubMedDate not supplied

Enhanced retention in the passive-avoidance task by 5-HT(1A) receptor blockade is not associated with increased activity of the central nucleus of the amygdala.

The effect of blockade of 5-HT1A receptors was investigated on (1). retention in a mildly aversive passive-avoidance task, and (2). spontaneous single-unit activity of central nucleus of the amygdala (CeA) neurons, a brain site implicated in modulation of retention. Systemic administration of the selective 5-HT1A antagonist NAN-190 immediately after training markedly-and dose-dependently-facilitated retention in the passive-avoidance task; enhanced retention was time-dependent and was not attributable to variations in wattages of shock received by animals. Systemic administration of NAN-190 had mixed effects on spontaneous single-unit activity of CeA neurons recorded extracellularly in vivo; microiontophoretic application of 5-HT, in contrast, consistently and potently suppressed CeA activity. The present findings-that 5-HT1A receptor blockade by NAN-190 (1). enhances retention in the passive-avoidance task, and (2). does not consistently increase spontaneous neuronal activity of the CeA-provide evidence that a serotonergic system tonically inhibits modulation of retention in the passive-avoidance task through activation of the 5-HT1A receptor subtype at brain sites located outside the CeA.

Action Potentials↗
PubMed2002

Postpartum urinary retention: assessment of contributing factors and long-term clinical impact.

OBJECTIVES: To investigate the relationships between various obstetric parameters and postpartum urinary retention, and to offer some clinical guidance for resolution of urinary retention problems. DESIGN: An observational prospective study. SETTING: A private teaching hospital medical centre. POPULATION: A total of 2,866 vaginally delivered women were recruited with 114 women classified as urinary retention group and the remaining 2752 women categorised as control group. MAIN OUTCOME MEASURES AND RESULTS: Women in the urinary retention and control groups did not differ significantly in terms of age, fetal head circumference and fetal birth weight. Women suffering from postpartum urinary retention demonstrated significantly longer labour duration, more nulliparity and epidural analgesia and higher percentages of instrument-assisted delivery and vaginal or perineal damage. CONCLUSION: Nulliparity, longer labour course, instrumental delivery, extensive vaginal and perineal laceration and use of epidural analgesia were contributing obstetric factors to postpartum urinary retention. Long-term follow-up showed that the problems of all but three of the 114 women, who complained of persistent minor urinary symptoms, were eventually resolved.

Adult↗
PubMed1990

Effect of undercut placement on crown retention after thermocycling.

The aim of this study was to examine the effect of undercuts in castings and/or tooth structure on the retention of crowns luted with glass ionomer cement. After routine full-crown preparations had been made in 48 human premolars, wax patterns were fabricated for each tooth. Retentive coves were then produced with a round bur in either the tooth structure or the wax patterns, or in both. One group of teeth and patterns did not receive any undercuts; this was the control group. Castings were made in non-precious metal. All crowns were luted with glass ionomer cement. Half of the samples were thermocycled, and the remainder were kept at 37 degrees C. Crowns were removed using tension (0.012 cm min-1) and the mean bond strengths calculated. The differences in retentive strengths were tested for statistical significance using ANOVA and Scheffe's test. The presence of coves in castings and/or tooth structure significantly increased the retentive strength of castings cemented with glass ionomer, as compared with conventional crown preparations without retentive undercuts. The effect of thermocycling on the retentive strength of castings cemented with glass ionomer was not statistically significant.

Analysis of Variance↗
PubMed2006

Urinary retention in women: its causes and management.

OBJECTIVE: To report the experience of the last 4 years from a centre to which women with voiding difficulties and urinary retention were referred nationally, describing what investigations were helpful in making a diagnosis and the management strategies used. PATIENTS AND METHODS: Women with voiding difficulties and urinary retention remain a diagnostic and management challenge, and those with no anatomical or neurological basis for their symptoms may be dismissed, assuming that their retention has a psychogenic basis. The finding of an electromyographic (EMG) abnormality of the striated urethral sphincter explaining their disorder (Fowler's syndrome) has led to the referral of women for consideration of that diagnosis. Thus we audited the referrals to the centre over a 4-year period of such women. RESULTS: In all, 247 women (mean age 35 years) with complete (42%) or partial retention (58%) were referred; 175 (71%) had urethral pressure profilometry, 141 (57%) had a transvaginal ultrasonographic measurement of the sphincter volume, and 95 (39%) had sphincter EMG. The mean maximum urethral closure pressure difference between patients with an EMG abnormality (101.5 cmH(2)O) and the patients with known other causes of voiding dysfunction (66.2 cmH(2)O) was 35.3 cmH(2)O (P < 0.05). In patients with complete retention there was a significant difference in sphincter volume between those who were EMG-positive (2.14 mL) or EMG-negative (1.64 mL) (P < 0.05). CONCLUSION: These investigations helped to classify the cause of retention in two-thirds of cases. The commonest diagnosis was Fowler's syndrome, in which sacral nerve stimulation is the only intervention that restores voiding.

Adolescent↗
PubMed2001

Retention of cast posts cemented with zinc phosphate cement using different cementing techniques.

PURPOSE: This study compares the effect of different cementation techniques on the retention of cast posts and cores. MATERIALS AND METHODS: Twenty-four extracted single rooted human teeth were used in this study. After routine preparation of the root canals, the canal space was enlarged with reamers. Direct post patterns were made with acrylic resin. Castings were fabricated using Ni-Cr-Mb alloy. Zinc phosphate cement was used as a luting agent using 4 different methods of cement introduction to the root canal space. This created 4 treatment groups consisting of 6 teeth in each group. In Group A, the cement was applied over the posts only. For the specimens in Group B, the cement was introduced into the root canals with a spiral filler and applied over the posts. In Group C, cement was injected into the root canals and then applied over the posts. Finally, for the specimens in Group D, cement was injected into the root canals and a spiral was used to spread it into the root canals, and cement was also applied over the posts. After cementation, teeth were stored in saline solution. The tensile retentive force of cast posts was evaluated using the Instron testing machine (Instron, Canton, MA). RESULTS: The retention obtained by the 4 techniques differed significantly (p <.05). The highest tensile force to post dislodgment was observed in Group D, and the least was in Group A. Analysis of variance test revealed a highly significant difference between groups (p <.0001). According to the Fisher exact test, there was a significant increase in retention from Group A to Group D (p <.05). CONCLUSIONS: Under the conditions of this study, the injection of cement into a root canal space followed by the use of a spiral resulted in the highest level of post retention. Retention was reduced when cement was placed using a Lentulo spiral alone (Kerr/Sybron Corp, Romulus, MI), a Jiffy tube (Teledyne Water Pik, Allegheny Teledyne Co, Fort Collins, CO) alone, or by application to the post only. J Prosthodont 2001;10:37-41.

Acrylic Resins↗