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At least 145 records · Page 8Linked to original sources

PubMedDate not supplied

Evaluation of retrievability of the Gunther tulip vena cava filter.

PURPOSE: To evaluate the feasibility and safety of withdrawal of a Gunther tulip retrievable vena cava filter (GTF). METHODS: Between June 2001 and December 2005, at our institution 86 GTFs were implanted for temporary caval filtration in 59 patients (37 women, 22 men; mean age 59.3 years, range 18-87 years). For GTFs retrieved thereafter, we retrospectively reviewed the following parameters: rate of success in retrieval, degree of trapped thrombus in the filter, and complications during retrieval. RESULTS: Worsening of or new development of pulmonary embolism after filter implantation did not occur in any patient. Of the 86 GTFs implanted, retrieval of 80 was attempted. Among those 80 filters, 77 (96%) were successfully retrieved (with the standard method, n = 72; with the modified method, n = 5) without any complication. The period of implantation of the retrieved filters was 13.4 +/- 4.2 days. In the 5 filters that were filled to a height of > or = 1/4 with trapped thrombus, retrieval was performed after attempts were made to decrease trapped thrombi. In addition, a temporary filter or another GTF was temporarily placed at the cephalad level of the GTF during this removal procedure. CONCLUSION: GTFs can be retrieved in the majority of cases. Even when encountering situations in which the filter could not be removed using the standard method, withdrawal was possible in a high frequency of cases through various trials using modified methods.

Adult↗

PubMed2004

DNA extraction from archival formalin-fixed, paraffin-embedded tissues: heat-induced retrieval in alkaline solution.

Based on the antigen retrieval principle, our previous study has demonstrated that heating archival formalin-fixed, paraffin-embedded (FFPE) tissues at a higher temperature and at higher pH value of the retrieval solution may achieve higher efficiency of extracted DNA, when compared to the traditional enzyme digestion method. Along this line of heat-induced retrieval, this further study is focused on development of a simpler and more effective heat-induced DNA retrieval technique by testing various retrieval solutions. Three major experiments using a high temperature heating method to extract DNA from FFPE human lymphoid and other tissue sections were performed to compare: (1) different concentrations of alkaline solution (NaOH or KOH, pH 11.5-12) versus Britton and Robinson type of buffer solution (BR buffer) of pH 12 that was the only retrieval solution tested in our previous study; (2) several chemical solutions (SDS, Tween 20, and GITC of various concentrations) versus BR buffer or alkaline solution; and (3) alkaline solution mixed with chemicals versus BR buffer or single alkaline solution. Efficiency of DNA extraction was evaluated by measuring yields using spectrophotometry, electrophoretic pattern, semiquantitation of tissue dissolution, PCR amplification, and kinetic thermocycling-PCR methods. Results showed that boiling tissue sections in 0.1 M NaOH or KOH or its complex retrieval solutions produced higher yields and better quality of DNA compared to BR buffer or chemical solutions alone. The conclusion was that boiling FFPE tissue sections in 0.1 M alkaline solution is a simpler and more effective heat-induced retrieval protocol for DNA extraction. Combination with some chemicals (detergents) may further significantly improve efficiency of the heat-induced retrieval technique.

Antigens↗

PubMed2006

Neural correlates of differential retrieval orientation: Sustained and item-related components.

Retrieval orientation refers to a cognitive state that biases processing of retrieval cues in service of a specific goal. The present study used a mixed fMRI design to investigate whether adoption of different retrieval orientations - as indexed by differences in the activity elicited by retrieval cues corresponding to unstudied items - is associated with differences in the state-related activity sustained across a block of test trials sharing a common retrieval goal. Subjects studied mixed lists comprising visually presented words and pictures. They then undertook a series of short test blocks in which all test items were visually presented words. The blocks varied according to whether the test items were used to cue retrieval of studied words or studied pictures. In several regions, neural activity elicited by correctly classified new items differed according to whether words or pictures were the targeted material. The loci of these effects suggest that one factor driving differential cue processing is modulation of the degree of overlap between cue and targeted memory representations. In addition to these item-related effects, neural activity sustained throughout the test blocks also differed according to the nature of the targeted material. These findings indicate that the adoption of different retrieval orientations is associated with distinct neural states. The loci of these sustained effects were distinct from those where new item activity varied, suggesting that the effects may play a role in biasing retrieval cue processing in favor of the current retrieval goal.

Adult↗

PubMed2005

Cross state-dependent retrieval between histamine and lithium.

Histamine and lithium state-dependent (StD) retrieval of passive avoidance task and their interactions was examined in mice. The pre-training or pre-test intracerebroventricular (i.c.v.) injection of histamine (20 microg/mouse) impaired retrieval when it was tested 24 h later. In the animals, in which retrieval was impaired due to histamine pre-training administration, pre-test administration of histamine, with the same dose, restored retrieval. The H1 blocker, pyrilamine (20 microg/mouse, i.c.v.), but not the H(2) blocker; ranitidine prevented the restoration of retrieval by pre-test histamine. The pre-training (5 and 10 mg/kg) or pre-test (5 mg/kg) injection of lithium also impaired retrieval, when it was tested 24 h later. In the animals that received lithium (5 mg/kg) or histamine (20 microg/mouse) as pre-training treatment, administration of histamine, clobenpropit or lithium, respectively, resulted in restoration of memory retrieval. Neither pyrilamine nor ranitidine prevented the restoration of retrieval by pre-test lithium. In conclusion, histamine or lithium can induce state-dependent retrieval and a cross-StD exists between these drugs, which may be mediated through the inositol pathway.

Analysis of Variance↗

PubMedDate not supplied

Retrievable IVC filter: preliminary in vitro and in vivo evaluation.

PURPOSE: To develop an inferior vena cava (IVC) filter that is retrievable even after neointimal formation and incorporation into the caval wall. MATERIALS AND METHODS: Eight filters were placed percutaneously in the infrarenal IVC of eight dogs. Four weeks after placement, percutaneous retrieval of the filters was attempted. Vena cavograms were obtained before and immediately after retrieval. Three dogs were killed immediately after the retrieval procedure was completed. In the other five dogs, follow-up vena cavography was performed 4-14 weeks after retrieval, and autopsy was performed. RESULTS: The filters were placed and retrieved successfully in all eight dogs. No migration, caval penetration, or tilting occurred. The IVCs were completely patent both before and immediately after retrieval in all eight dogs. In the three dogs killed immediately after retrieval, neointimal hyperplasia was seen around the struts, but there was no detachment. Delayed stenosis was not seen in any of the five dogs that were followed up, and the inner surface of the caval wall was smooth. CONCLUSION: This IVC filter can be easily placed and safely retrieved percutaneously, even after neointimal formation.

Animals↗

PubMedDate not supplied

Extremely dilute modular neuronal networks: neocortical memory retrieval dynamics.

A model of columnar networks of neocortical association areas is studied. The neuronal network is composed of many Hebbian autoassociators, or modules, each of which interacts with a relatively small number of the others, randomly chosen. Any module encodes and stores a number of elementary percepts, or features. Memory items, or patterns, are peculiar combinations of features sparsely distributed over the multi-modular network. Any feature stored in any module can be involved in several of the stored patterns; feature-sharing is in fact source of local ambiguities and, consequently, a potential cause of erroneous memory retrieval spreading through the model network in pattern completion tasks. The memory retrieval dynamics of the large modular autoassociator is investigated by combining mathematical analysis and numerical simulations. An oscillatory retrieval process is proposed that is very efficient in overcoming feature-sharing drawbacks; it requires a mechanism that modulates the robustness of local attractors to noise, and neuronal activity sparseness such that quiescent and active modules are about equally noisy to any post-synaptic module.Moreover, it is shown that statistical correlation between 'kinds' of features across the set of memory patterns can be exploited to obtain a more efficient achievement of memory retrieval capabilities. It is also shown that some spots of the network cannot be reached by retrieval activity spread if they are not directly cued by the stimulus. The locations of these activity isles depend on the pattern to retrieve, while their extension only depends (in large networks) on statistics of inter-modular connections and stored patterns. The existence of activity isles determines an upper-bound to retrieval quality that does not depend on the specific retrieval dynamics adopted, nor on whether feature-sharing is permitted. The oscillatory retrieval process nearly saturates this bound.

Animals↗

PubMed1983

Role of the infraorbital nerve in retrieving behavior in lactating rats.

Injecting the local lidocaine into the mystacial pads of primiparous rats rendered the snout insensitive to touch and abolished the dams' ability to retrieve. Injecting the drug into the masseter muscles or intraperitoneally did not render the snout anaptic or abolish retrieval, results indicating that the effect of intramystacial lidocaine treatment could not be attributed to systemic toxicity or to the drug's spreading from the mystacial pads to affect the nearby masseter muscles. Cutting the intraorbital nerves produced a temporary retrieval impairment that was indistinguishable from that produced by intramystacial lidocaine injection. Surgical deafferentation did not affect the latency of dams to approach pups that had been displaced from the nest site, which indicates that the retrieval deficit was not due to postoperative debilitation. In addition, infraorbital section did not interfere with the ability to locate and consume a piece of cheese that had been buried in the home cage, which indicates that the operation did not produce anosmia or interfere with the muscles used to grasp pups. Cutting the facial nerves abolished vibrissal movement but did not disrupt retrieval, results indicating that the effect of infraorbital lesions could not be attributed to the loss of vibrissal cues or to nonspecific effects of nerve section. The possibility was tested that infraorbital deafferentation has a profound effect on retrieval because anaptic dams, in their initial attempts at picking up pups, elicit distress vocalizations from their offspring. Dams injected with lidocaine in the mystacial pads failed to retrieve pups that had been anesthetized with a barbiturate to abolish their distress vocalizations. Thus pup-produced vocalizations are not responsible for the retrieval impairment exhibited by anaptic mothers. It is concluded that perioral tactile sensation plays an important role in the ability of lactating rats to retrieve.

Animals↗

PubMed2001

Temporal characterization of memory retrieval processes: an fMRI study of the "tip of the tongue" phenomenon.

"Tip of the tongue" (TOT) is a natural phenomenon in which people cannot retrieve a target word immediately, even though they feel confident that they know the target. This provides us an opportunity to understand the human memory system, because cognitive components of memory retrieval such as retrieval effort and successful retrieval are temporally dissociated from each other during the TOT states. The purpose of the present study was to reveal the neural correlates of the cognitive components of the retrieval process by separating cognitive phases of the TOT phenomenon using event-related functional magnetic resonance imaging with multiple regression analysis. We demonstrated that the left dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex were activated at the time of successful retrieval, and the left DLPFC also showed activation when the subjects successfully retrieved the target names as compared to when they gave up. This result suggests that the left DLPFC is specific to the successful retrieval process. During the TOT state, a number of regions were activated, and this suggests that widely distributed brain regions are engaged when people make a hard effort to retrieve a proper name in the TOT state. Our new approach employing temporal resolution of the TOT phenomenon may contribute to the understanding of the mechanisms of the human memory system.

Adult↗

PubMed1997

Associative priming in word fragment completion: a dissociation between explicit and implicit retrieval processes.

Three experiments investigated associative priming in word fragment completion. In associative priming, the study word that acts as a prime is semantically related in some way to the response word that the subject must produce or respond to at test. For example, a prime might be semantically related to the solution to its paired word fragment (e.g. study "VANILLA", solve fragment "-H-C--A-E" at test, solution is "CHOCOLATE"). Associative priming therefore differs from both repetition and conceptual priming, in which the studied primes are themselves the words that must be produced or responded to at test. In Experiment 1, associative primes were found to influence word fragment completion performance on an explicit test, but not on an implicit test. Experiment 2 demonstrated that the effects of associative primes on explicitly instructed fragment completion cannot be attributed to the specific information about cue-prime relationships that is included in the explicit instructions. Experiment 3 demonstrated that a manipulation of modality, a variable known to disrupt implicit retrieval processes, disrupts repetition priming on an explicit test, but not associative priming. The results of these three experiments suggest that whereas repetition primes are retrieved from memory by both explicit and implicit retrieval processes, associative primes are retrieved by only explicit processes. These data suggest that implicit retrieval processes are cue-dependent processes which automatically retrieve memory information that provides a good match to retrieval cues. Explicit retrieval processes are cue-independent, functioning as an intentional retrieval set to access particular categories or types of memory information.

Association↗

PubMed2002

Hippocampal and brain stem activation during word retrieval after repeated and semantic encoding.

Repeated word presentation during learning and the use of a semantic encoding task both increase the accuracy of subsequent word retrieval. Previous neuroimaging studies have shown that successful word retrieval depends on the recruitment of the hippocampus, whereas the effort of retrieval is linked to activation of prefrontal cortex modules. We studied the effects of repetition (4x versus 1x presentation) and encoding task (semantic versus perceptual) on hippocampal and prefrontal cortex activation during word-stem cued recall using positron emission tomography. Repeated and semantic encoding resulted in increased recall accuracy, with word repetition showing a greater effect when using a semantic encoding task. The more successful retrieval of words presented repeatedly compared with words presented once was associated with activation of the left anterior hippocampus. The more successful retrieval of words encoded using a semantic compared with a perceptual task was associated with activation of the right posterior and, less significantly, the left anterior hippocampus. The greater benefit of repeated learning when using the semantic task was linked to activation of the right brainstem, in the region of the ventral tegmentum. Our results suggest that word repetition and semantic encoding increase recall accuracy during subsequent word retrieval via distinct hippocampal mechanisms and that ventral tegmentum activation is relevant for word retrieval after semantic encoding. These findings confirm the importance of hippocampal recruitment during word retrieval and provide novel evidence for a role of brainstem neurons in word retrieval after semantic encoding.

Adult↗

PubMed1994

Percutaneous transcatheter retrieval of misplaced therapeutic embolisation devices.

OBJECTIVE: To assess the incidence and subsequent management of misplaced devices as a complication of therapeutic embolisation procedures. DESIGN: Retrospective review of case notes, cardiac catheterisation reports, and angiograms. SETTING: Tertiary referral centre for congenital heart disease. PATIENTS: 205 consecutive children and adults undergoing therapeutic embolisation for congenital heart disease in the 10 years up to 1 April 1993. This group had 231 therapeutic embolisation procedures at 241 sites using coils, umbrella devices, or detachable balloons. MAIN OUTCOME MEASURES: Incidences of misplacement and retrieval of the device; morbidity and mortality. RESULTS: The incidence of misplacement was 3% (10/332) of devices deployed and 4.3% (10/231) of procedures performed. Retrieval from distal pulmonary arteries was not attempted in two patients, but transcatheter retrieval of coils and umbrellas from systemic and pulmonary vessels, using snares or retrieval baskets, was successful in the remaining eight. There were no deaths or serious sequelae related to the procedure, but one patient required femoral arteriotomy for removal of an umbrella device retrieved only as far as the groin. In four of the five most recent cases, the misplaced device was retrieved and the therapeutic embolisation was completed at the same procedure. CONCLUSIONS: Misplacement of a device during therapeutic embolisation is a recognised complication that can be satisfactorily dealt with by transcatheter retrieval without recourse to surgery. For retrieval to be successful it is important to have a wide selection of retrieval equipment available and to be conversant with its use.

Adolescent↗

PubMed2002

Specimen retrieval in laparoscopic colon surgery.

In the past decade, for benign as well as malignant colon diseases, minimally invasive surgery has gained more and more importance in colon surgery. Specimen retrieval after colonic resections is difficult due to the large size of the specimen usually resected. To date there is no standardized retrieval technique for the different procedures. Four incision sites are common for transabdominal specimen retrieval: left or right lower quadrant transrectal portside incision; periumbilical midline incision, and transverse suprapubic incision. Perineal incisions are used for retrieval following low anterior resection or abdomino-perineal extirpation. Three major complications are described in the literature: wound infection (0-9%); hernias (0-2%), and incision site recurrence (0-1.3%). There are no significant differences between the different incision sites with regard to the occurrence of complications. In laparoscopic surgery for malignant diseases retrieval is usually performed using a plastic bag, whereas retrieval can be performed hand-assisted without a bag during surgery for benign diseases. Wound edge protectors are recommended by several authors, yet there is no standard system which is accepted broadly. In conclusion, specimen retrieval in laparoscopic colon surgery is not standardized. The morbidity rate for specific retrieval complications ranges between 0 and 9%, yet there are no randomized controlled studies or evidence-based data regarding different retrieval approaches and systems.

Colonic Diseases↗

PubMed2003

Clinical experience with retrievable Günther Tulip vena cava filters.

PURPOSE: To report clinical experience with retrievable Günther Tulip filters from implantation to retrieval and their status in nonretrieved situations. METHODS: Seventy-five Günther Tulip filter implantations were performed in 71 patients (43 women; mean age 55 years). Indications for filter placement were pulmonary embolism (PE) or iliofemoral deep vein thrombosis (DVT) in patients with a contraindication to anticoagulation (43, 61%) or perioperative PE prophylaxis (28, 39%) in patients with confirmed iliofemoral DVT. Retrieval procedures were planned for each patient. Patients with nonretrieved filters were followed with plain radiography and duplex sonography. RESULTS: Technical success of filter insertion was 97.3% (73/75). Eighteen (25%) patients died from unrelated causes prior to retrieval attempts, and 6 other patients were too critically ill for a retrieval procedure. Of 49 (67%) planned retrieval attempts, 14 (19%) filters could not be removed owing to large trapped thrombi. The mean implantation period for the 35 (48%) retrieved filters was 8.2 days (range 1-13). Delivery tilt was observed in 12 (16%) filters and during retrieval attempts in 1 more case. For 9 nonretrieved filters, tilt and migration were observed in 22% at a mean follow-up of 30 months, but no venous thrombosis was assessed. CONCLUSIONS: Our data confirm the clinical efficacy of the Günther Tulip filter during implantation and the feasibility of its retrieval. Further long-term follow-up should be conducted on nonretrieved filters to confirm our results.

Adult↗

PubMed2002

Influence of the test situation on pup retrieval behavior of normal and undernourished lactating rats.

Undernutrition of dams and pups disrupts the retrieval efficiency of mothers. However, if the mothers are assessed in their home cages, they spend more time with their litters. In the present study the effect of test conditions on pup retrieval behavior of mothers receiving a 25% (well-nourished group) and 8% casein diet (undernourished group) was examined. In agreement with previous studies, undernourished mothers spent more time with their litters than well-nourished dams as lactation proceeded. Pup retrieval behavior varied with test conditions. In the first experiment, the maternal behavior of dams was assessed by the standard procedure (pups were separated from their mother and scattered over the floor of the home cage). The mother was then returned and the number of retrieved pups was recorded. From day 3 to 8, the retrieval efficiency of undernourished dams decreased, while the retrieval efficiency of well-nourished mothers did not vary. In the second experiment, mothers were subjected to a single retrieval test (on day 9 of lactation) using the procedure described for experiment 1. No difference between well-nourished and undernourished mothers was observed. In the third experiment, seven-day-old pups were separated from the mothers and returned individually to a clean home cage. Dietary treatment did not affect the retrieval efficiency. However, undernourished dams reconstructed the nest more slowly than did well-nourished dams. Taken together, these results suggest that pup retrieval behavior of the undernourished mother is not impaired by dietary restriction when the maternal environment is disturbed minimally.

Analysis of Variance↗

PubMedDate not supplied

Hereditary spectrin deficiency in Golden Retriever dogs.

Spectrin deficiency with increased erythrocyte osmotic fragility (OF) is a hallmark of hereditary spherocytosis, which is the most common congenital hemolytic anemia in humans of northern European ancestry. A radioimmunoassay revealed that erythrocyte spectrin concentration was 50-65% of normal in 5 adult Golden Retriever dogs, which had recovered from hemolytic anemia but whose OF had persistently remained increased. OF also was increased and spectrin concentration was decreased (60-73%) in 10 dogs of an apparently healthy family of 19 Golden Retrievers related to a proband. Pedigree analysis revealed autosomal dominant inheritance. In addition, OF was increased in 23 (17%) of 134 randomly chosen Golden Retrievers with nonhematologic diseases. In these Golden Retrievers, the spectrin concentration was decreased in 5 dogs with increased OF and within the reference range in 6 dogs with normal OF, indicating that in this population spectrin deficiency and increased OF are highly associated (P < .002). Considering these patients a representative sample of the Golden Retriever population in the Netherlands, spectrin deficiency may occur in 11.2-24.6% of Dutch Golden Retrievers (confidence level = 0.95). In blood smears, spherocytes were recognized only in dogs with immune-mediated anemia. At scanning electron microscopy, blood from spectrin-deficient Golden Retrievers showed slight crenation when fixed freshly but abundant echinospherocytes after 24 hours of incubation. We conclude that occult autosomal dominant spectrin deficiency occurs in dogs and is frequent in Dutch Golden Retrievers. It is not clear whether spectrin deficiency in Golden Retrievers may result in hemolytic anemia, as in humans.

Animals↗

PubMed1999

Intrasubtest scatter on the WAIS-III information subtest and psychometrically defined retrieval deficits.

Milberg, et al. (1996) postulated that significant intrasubtest scatter on the Wechsler Information subtest reflects impaired retrieval. From a pool of 205 male referrals at a VA medical center with complete WAIS-III and WMS-III protocols, 28 participants with impaired retrieval (Group I) defined by a high Retrieval Composite score were identified. A sample (Group II) without similar evidence of impaired retrieval was matched to Group I on age, education, Full Scale IQ, race, and diagnosis. Intrasubtest scatter on the Information subtest was the same across groups (Group I M = 6.3, SD = 2.7; Group II M = 6.9, SD = 3.4). A second study identified impaired retrieval using the WMS-III Word Lists subtest. 21 participants (Group III) had impaired retrieval indicated by a Recognition scaled score being > or = 4 points higher than the Delayed Recall scaled score. A matched sample (Group IV) of VA patients without similar evidence of impaired retrieval was constituted. Intrasubtest scatter on the Information subtest did not differ across groups (Group III M = 6.6, SD = 2.4; Group IV M = 6.0, SD = 2.5). Evaluations of the retrieval deficit hypothesis should be based on responses of participants whose Information performance is characterized by abnormal amounts of intrasubtest scatter. It is possible that a specific amount of response variability must be present within the subtest before retrieval problems can be detected.

Adult↗

PubMed2005

When and why is ease of retrieval informative?

In two experiments, we examined when and why ease of retrieval of information from memory affects behavioral frequency and attitudinal judgments. Overall, the results suggest that when the subjective experience of ease of retrieval is consistent with the expected ease of retrieval, the content of the information retrieved is used to make judgments. However, when there is a discrepancy between experienced and expected ease of retrieval, the subjective experience of ease of retrieval is used to make judgments. Ease of retrieval is more informative when the discrepancy between experienced and expected ease of retrieval cannot be attributed to task contingencies; when it can, ease of retrieval ceases to be informative.

Attitude↗

PubMed2004

An integrated content and metadata based retrieval system for art.

A new approach to image retrieval is presented in the domain of museum and gallery image collections. Specialist algorithms, developed to address specific retrieval tasks, are combined with more conventional content and metadata retrieval approaches, and implemented within a distributed architecture to provide cross-collection searching and navigation in a seamless way. External systems can access the different collections using interoperability protocols and open standards, which were extended to accommodate content based as well as text based retrieval paradigms. After a brief overview of the complete system, we describe the novel design and evaluation of some of the specialist image analysis algorithms including a method for image retrieval based on sub-image queries, retrievals based on very low quality images and retrieval using canvas crack patterns. We show how effective retrieval results can be achieved by real end-users consisting of major museums and galleries, accessing the distributed but integrated digital collections.

Abstracting and Indexing↗