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PubMed2005

Is there a benefit from routine follicular flushing for oocyte retrieval?

The object of this study was to determine the optimum number of follicular flushing for a maximum number of oocytes to be retrieved. This was a prospective study, based at a private in vitro fertilization centre (Brentwood Fertility Centre, The Essex Nuffield Hospital, Brentwood, Essex UK). Patients attending the IVF centre for assisted reproductive technology were studied. We counted the number of oocytes obtained with each flushing after primary aspiration of the follicle. Some 40% of the oocytes were retrieved with primary aspiration without follicular flushing, while up to 82% of oocytes were retrieved with two flushes and 97% of oocytes were retrieved in up to four flushes. Only 3% of the remaining oocytes were retrieved with 5th and 6th flush. The optimum number of follicular flushing was four times, in order to achieve maximum number of oocytes without compromising the duration of retrieval and number of oocytes retrieved.

Adult↗

PubMed1991

Automatic temporal order judgment: the effect of intentionality of retrieval on closed-head-injured patients.

Closed-head-injured (CHI) and control groups were tested on a temporal order task under intentional and incidental retrieval conditions. Subjects were given five presentations of a list of nouns. In the incidental retrieval condition, subjects were told that they were to remember the words but that the order was not important. In the intentional retrieval condition, subjects were given the words in an order different from that in which they were originally presented and were asked to reorder the words to match the original order. For both conditions we compared the order in which words were recalled to the order in which they were originally presented. The results suggest that temporal order memory had more effortful characteristics in the intentional than in the incidental retrieval condition. The two groups did not differ significantly in the incidental retrieval condition. However, while the control group showed a significant improvement in the intentional retrieval condition. CHI groups performance did not significantly change. This study highlights two major points: (1) intentionality at the retrieval stage determines the effortfulness with which information is processed; (2) the more automatic the tasks, the better it is preserved following closed-head injury.

Adolescent↗

PubMed2005

Retrieval and releasing capabilities of stone-basket designs in vitro.

BACKGROUND AND PURPOSE: A serious problem during calculus retrieval is the inability to release a stone from the basket. We evaluated a variety of basket designs to address this issue in two in-vitro models. MATERIALS AND METHODS: Four baskets--a modified, flat-wire, a double-helical, and two tipless Nitinol models (a passive and an articulating type)--were evaluated. The ability to retrieve and release beads of 4, 6, 8, 10, 12, and 14 mm diameter was compared in both a ureteral and a caliceal model. RESULTS: In the ureteral model, all baskets were successful in retrieving all sizes of beads as long as the bead was smaller than the measured basket diameter. Only the articulating (all sizes) and larger non-articulating Nitinol models were able to release each of the bead sizes once engaged. The double-helical basket (larger size only) was able to release only the 4- and 6-mm beads after retrieval. For the 10- and 12-mm beads, the respective articulating Nitinol baskets could liberate the bead only when the articulating mechanism was used. In the caliceal model, the flat-wire and double-helical baskets were unsuccessful in all attempts at retrieval. The larger non-articulating Nitinol model was successful for beads >8 mm but had difficulty retrieving those smaller. Only the articulating Nitinol models were able to engage and release each of the beads. CONCLUSION: From these in-vitro studies, it is apparent that the Nitinol basket designs have the best retrieval capabilities. The ability to articulate the basket improves release of a stone once engaged.

Alloys↗

PubMed2006

Splenic retrieval after laparoscopic splenectomy: a new bag.

BACKGROUND: Laparoscopic splenectomy has become the gold-standard surgical approach for patients undergoing elective splenectomy. Little data exist concerning the technical difficulties of splenic retrieval. When the spleen is large, popular commercial retrieval bags are often too small to facilitate removal. The aim of this study was to compare our clinical experience utilizing two different retrieval bags, the Endocatch II (Autosuture, London, UK) and the developing E200 (Espiner Ltd., Bristol, UK). MATERIALS AND METHODS: We performed a retrospective review of all laparoscopic splenectomies performed at Hull Royal Infirmary, Kingston upon Hull, from March 1997 to July 2003. Patient demographics, morbidity, mortality, and clinical outcome had been entered prospectively into a database. Two patient groups were examined, depending on the type of retrieval bag utilized. Complications and instrument failure during splenic retrieval were analysed. RESULTS: A total of 83 laparoscopic splenectomies were performed. No retrieval bag was used in 8 cases (10%). The Endocatch retrieval bag was used for 45 (60%) patients and the E200 for 30 (40%) patients. The mean operative time for the former group was 65 minutes (range, 50-127 minutes) and for the latter, 120 minutes (range, 80-180 minutes) (P < 0.05). Bag-related complications were 2 (4%) perforations and 2 (4%) failures to deploy while using the Endocatch bag. CONCLUSION: The Endocatch bag is easy to deploy but is associated with perforation and cannot be used for large spleens. The E200 bag is more useful for large spleens but is associated with prolonged operative time due to poor maneuverability. Improved technology is still required.

Adult↗

PubMed2003

Neuroanatomical correlates of episodic encoding and retrieval in young and elderly subjects.

Lesion studies have shown convincingly that the medial temporal lobes (MTL) and frontal lobes are critical to episodic memory. Ageing generally has been found to have a generally negative effect on episodic memory performance, which might relate to neurofunctional changes in the frontal and medial temporal brain regions. In the present study, we used functional MRI (fMRI) to investigate separately the contributions of encoding and retrieval to the age-related decline in memory. To this end, we compared brain activity patterns obtained during incidental encoding (pleasant/unpleasant judgements about nouns) and subsequent retrieval (recognition) in three groups: a group of young subjects, a group of elderly subjects showing reduced memory performance (ELD-RED), and a group of elderly subjects who still performed in the normal range (ELD-NORM). This allowed us to differentiate between age-related changes in brain activity that affect memory function and those that do not have an apparent effect on memory function, because they are found in both elderly groups. Contrary to previous imaging studies on this topic, we used (self-paced) event-related fMRI to control for differences in performance level across groups by including correct responses only. Comparing the encoding of successfully remembered items with baseline (press left/press right), the young subjects showed a significant increase in brain activation in the left anterior MTL compared with the ELD-RED but not the ELD-NORM subjects. Comparing correctly rejected items (retrieval attempt) with baseline, the ELD-RED group showed much increased overall activity throughout the brain compared with the other groups. However, when correctly recognized items (retrieval attempt + success) were compared directly with correctly rejected items (retrieval attempt), these differences were greatly reduced, revealing common activity in the left parietal, retrosplenial and left anterior prefrontal regions. Therefore, we conclude that the reduced performance in the ELD-RED group is likely to be due to MTL dysfunction during encoding. The differences observed during retrieval attempts may reflect strategic differences. The lack of differences observed in relation to retrieval success suggests that ageing does not affect the processes that support the actual recovery of information.

Adult↗

PubMed2004

Sperm retrieval techniques in rats with suppressed spermatogenesis by experimental cryptorchidism.

OBJECTIVE: Our aim was to assess the suppression of spermatogenesis and sperm retrieval rate after testicular sperm extraction (TESE) or testicular sperm aspiration (TESA) in adult rats with surgically induced cryptorchidism. METHODS: Adult rats were submitted to TESE and TESA procedures after 15 days of induced cryptorchidism. After spermatozoa retrieval, the testicles were extracted, weighed and a morphological analysis by conventional light microscopy was done. The numbers of spermatozoa retrieved in both TESA and TESE were rated and compared. RESULTS: Histological analysis of the testicles revealed Sertoli cell-only syndrome in 60% of the testicles, and maturation arrest in the remaining cryptorchid testicles. Significant differences were seen in the number of spermatozoa retrieved (P < 0.05) between cryptorchidic and control rats. When sperm retrieval techniques were compared, no differences were detected in the number of spermatozoa obtained (P > 0.05). CONCLUSIONS: It seems that a 15 day period of cryptorchidism is enough to induce spermatogenesis disorders. No differences were detected in the number of spermatozoa retrieved in the right or left testicles, irrespective of the testicular pole. Furthermore, and even more importantly, no differences in the retrieval rate were seen between the two techniques.

Animals↗

PubMed2002

Development of a highly sensitive search strategy for the retrieval of reports of controlled trials using PubMed.

OBJECTIVE: To develop, through revision of the Cochrane Collaboration search strategy for OVID-MEDLINE, a highly sensitive search strategy to retrieve reports of controlled trials using PubMed. METHODS: The original highly sensitive Cochrane strategy was revised to take into account additional Medical Subject Headings (MeSH) and other terminology as well as the current unique features of PubMed. We compared the retrieval of the revised strategy with that of the original Cochrane strategy before and after translation of the strategies into PubMed format. Finally, we used a gold standard database of reports of controlled trials identified by electronic and hand search of selected journals to test the revised strategy in PubMed format. RESULTS: The revised strategy included a search statement modified for increased precision, and added 'Cross-over Studies' as a MeSH term and the term 'latin square' as a text word. Compared to the original Cochrane strategy, the revised strategy identified 53 additional reports of controlled trials accessing MEDLINE through OVID. When the revised strategy and original Cochrane strategy were translated into PubMed format, the revised strategy retrieved 90 reports of controlled trials not identified by the original strategy. Finally, the revised strategy in PubMed format retrieved all of the reports of controlled trials in the gold standard database. Ninety-eight per cent of the gold standard reports of controlled trials were retrieved by Phase 1 of the optimal PubMed search strategy. CONCLUSIONS: Failure to identify all relevant trials for systematic review could result in bias. We developed a highly sensitive search strategy for the retrieval of reports of controlled trials for use with PubMed that retrieves more relevant citations (greater sensitivity) and fewer non-relevant citations (greater precision) than the original Cochrane search strategy.

Bias↗

PubMed1995

Antigen retrieval in immunofluorescent testing of bullous pemphigoid.

Direct immunofluorescence is an immunopathological technique frequently utilized for diagnosis of vesiculobullous disease such as bullous pemphigoid. Fresh-frozen tissue is required for immunofluorescent testing, making retrospective analysis difficult. In this study, we compared two methods of antigen retrieval in formalin-fixed, paraffin-embedded skin tissue from patients with bullous pemphigoid to determine if archival tissue, after use of an unmasking antigen, can be substituted for fresh-frozen tissue in the immunopathological study of skin. Paraffin-embedded tissue blocks from patients with bullous pemphigoid and patients with eosinophilic spongiotic dermatitis as the prodromal stage of bullous pemphigoid were obtained. Sections were mounted on poly-L-lysine-coated slides and the slides were deparaffinized. The methods of antigen retrieval included incubation with trypsin (0.1%) and microwave irradiation in urea (6 M). Antigen retrieval was followed by indirect immunofluorescence. Microwave irradiation was more effective in antigen retrieval than was incubation with trypsin (0.1%). Microwave irradiation in urea (6 M) produced more intense immunofluorescent staining than did trypsinization. Overall, positive basement membrane zone immunofluorescent staining was found in 60% of patients with a diagnosis of classical bullous pemphigoid and in 50% of patients with eosinophilic spongiotic dermatitis as the prodromal stage of bullous pemphigoid. Although the frozen-tissue method appeared more effective than the antigen-retrieval method in immunofluorescent testing of skin, the antigen-retrieval method can certainly be considered an option in retrospective studies. Antigen retrieval may be particularly advantageous in patients with eosinophilic spongiotic dermatitis in whom the diagnosis of bullous pemphigoid may not be suspected initially.

Antigens↗

PubMed1995

Functional role of the prefrontal cortex in retrieval of memories: a PET study.

Retrieval of information from episodic memory involves the processes invoked by the attempt to remember (retrieval attempt) as well as processes associated with the successful retrieval of stored information (ecphory). Previous PET studies of memory have shown an activation of the prefrontal cortex in memory retrieval tasks, and we hypothesised that this activation represents retrieval attempt, not ecphory. This hypothesis was directly directed using [15O]H2 PET imaging in 19 healthy subjects who performed three matched tasks which involved different levels of retrieval attempt and ecphory. The results showed that retrieval attempt was associated with activation of the prefrontal cortex, right greater than left, while ecphory involved the posterior cortical regions. These findings illuminate the functional role of the different neuroanatomical regions involved in episodic remembering.

Adult↗

PubMed2001

Formalin-fixed and heat-retrieved tissue antigens: a comparison of their immunoreactivity in experimental antibody diluents.

Heat-induced antigen retrieval procedures have become an effective and therefore important part of immunohistochemistry. Although used with increasing frequency, it is not known by what mechanism or to what extent these procedures restore the molecular integrity of the antigen. In an attempt to explore these questions, the immune reactions of 14 tissue antigens with their corresponding monoclonal antibodies were compared both in the absence and after the application of two widely used heat-induced antigen retrieval procedures. The tissue antigens were selected either because of the increased or lack of response to heat retrieval. The nature of their immune reactions was appraised through the variable effects that some diluent solutes were previously shown to have on monoclonal antibodies at different pH. It was found that on heat retrieval, four antigens reacting with monoclonal antibodies of subclass IgG2a or IgG1 reversed their preference for an alkaline pH to that of an acid pH. Eight of nine antigens reacting with monoclonal antibodies of subclass IgG1 and one antigen reacting with an antibody of class IgM remained most reactive at pH 6.0. The retrieved epitope of a B-cell antigen reacting with an IgG3 subclass antibody retained its preference for the alkaline pH. These patterns of response by the antigens to heat-induced retrieval are compared with the previously reported modifications in the immune reactions of monoclonal antibodies when sodium chloride and sodium phosphates were included in the antibody diluent buffer. Use of antibody diluents containing these solutes in combination with heat-induced antigen retrieval resulted in the loss of most of the sensitivity gained through this technique. The possible common mechanisms underlying the causes for these results are discussed.

Antibodies, Monoclonal↗

PubMed2002

Superheating antigen retrieval.

Heat-induced antigen retrieval in a variety of solutions has been shown to enhance the immunoreactivity of a wide range of antigens in routine formalin-fixed, paraffin-embedded tissues. Accurate time and temperature control is important for standardization and optimization of the procedure but is difficult to achieve. This study used a device to attain precise time and temperature control for antigen retrieval at 120 degrees C under 1.9 bar pressure. It compares the efficacy of this method with antigen retrieval in a conventional pressure cooker, by microwave heating at 98 degrees C, and ultrasound retrieval at 40 and 70 W for 40 and 100 seconds. Multitissue and multitumor blocks containing a spectrum of normal tissues and a variety of tumors, respectively, were used, and 42 routine diagnostic antibodies were applied with a standard peroxidase conjugated streptavidin technique. Sections in which antigen retrieval was not performed served as controls. The three heat-induced methods showed distinctly better immunostaining for all antigens compared with those obtained with ultrasound retrieval. The latter method did not produce consistent staining and intensity, and the extent of staining was only marginally better than sections not subjected to antigen retrieval. Superheating at 120 degrees C produced the best overall results with the exception of antibodies to cytokeratin clones Cam 5.2, AE1/3, and 34BE12 in which superheating resulted in slightly inferior immunostaining compared with heating in a pressure cooker and at 98 degrees C.

Antigens↗

PubMed2003

A new optional vena cava filter: retrieval at 12 weeks in an animal model.

PURPOSE: To test the feasibility and safety of percutaneous retrieval of a new inferior vena cava (IVC) filter, the Recovery Filter (RF), acutely and after 12-week implantation in sheep. MATERIALS AND METHODS: The RF is a bilevel filter with stabilizing arms and elastic hooks that allow retrieval with a unique retrieval cone after incorporation into the wall of the IVC. Twenty-four filters were placed in the infrarenal IVCs of 18 sheep. In six sheep, two filters were placed and then removed immediately; three sheep were killed acutely and three were killed after a healing period of 3 weeks. In 12 sheep, a single filter was placed and then removed 12 weeks later; six were killed after retrieval and six were killed after an 8-week healing period. RESULTS: The mean (+/-SD) transverse vena caval diameter was 15.3 mm +/- 2. All filters were deployed as intended and retrieved without difficulty. At sacrifice, there was no evidence of IVC perforation or retroperitoneal abnormality. The IVCs of the animals in the acute retrieval group showed minimal acute superficial injury that was largely reversed at 3 weeks. At 12 weeks, there was evidence of transmural incorporation of filter elements with narrowing of the IVCs. Solitary fibrotic abnormalities were present in the aorta adjacent to IVC lesions in nine of the 12 animals in the 12-week group. The IVC and aortic abnormalities were largely healed, with reversal of IVC narrowing after 8 weeks. CONCLUSION: The recovery filter can be reliably and safely retrieved acutely and 12 weeks after implantation in sheep.

Animals↗

PubMed2006

Günther Tulip filter retrievability multicenter study including CT follow-up: final report.

PURPOSE: To evaluate the safety and effectiveness of retrieval of the Günther Tulip inferior vena cava (IVC) filter. MATERIALS AND METHODS: This was a nonrandomized, single-armed, multicenter prospective investigation. Patients at temporary high risk for pulmonary embolism (PE) or deep vein thrombosis (DVT) who did not require a permanent filter were eligible. Forty-one patients received 42 Günther Tulip filters: 22 men and 19 women with a mean age of 47.7 years. Indications for filter placement included prophylaxis, PE, and DVT. Three months after filter retrieval, contrast agent-enhanced computed tomography of the abdomen, jugular vein ultrasonography, and clinical follow-up were performed. RESULTS: The filter retrieval rate was 57% (23 of 41). Günther Tulip filters were removed at a mean of 11.1 days (range, 2-14 d). The technical and clinical success rates for filter retrieval were both 100%. One placement complication and two protocol deviations occurred. These patients were excluded in terms of retrieval-related outcomes. One case of PE occurred with a filter in place, and one filter migrated to the heart. There were no acute complications caused by filter retrieval. At 3-month follow-up, there was no recurrent PE, DVT, jugular vein occlusion, or IVC stenosis or occlusion. CONCLUSION: In this multicenter study, retrieval of the Günther Tulip filter was safe and without recurrent thromboembolic events or evidence of IVC or jugular vein damage at 3-month follow-up.

Adult↗

PubMedDate not supplied

Modulation of retrieval processing reflects accuracy of emotional source memory.

There is considerable evidence that encoding and consolidation of memory are modulated by emotion, but the retrieval of emotional memories is not well characterized. Here we manipulated the emotional context with which affectively neutral stimuli were associated during encoding, allowing us to examine neural activity associated with retrieval of emotional memories without confounding the emotional attributes of cue items and the retrieved context. Using a source memory procedure we were also able to compare how retrieval processing was modulated when the emotional encoding context was recollected or not. An interaction between emotional encoding context and accuracy of source memory revealed that successful retrieval of emotional context was associated with activity in left amygdala, and a left frontotemporal network including anterior insula, prefrontal cortex and cingulate. In contrast, when contextual retrieval was unsuccessful, items encoded in emotional contexts elicited enhanced activity in right amygdala and a right-lateralized network that included extrastriate visual areas. These findings indicate distinct effects of emotion on successful and unsuccessful retrieval of source information, including lateralization of amygdala responses.

Adolescent↗

PubMed2005

Electromagnetic parameter retrieval from inhomogeneous metamaterials.

We discuss the validity of standard retrieval methods that assign bulk electromagnetic properties, such as the electric permittivity epsilon and the magnetic permeability mu, from calculations of the scattering (S) parameters for finite-thickness samples. S-parameter retrieval methods have recently become the principal means of characterizing artificially structured metamaterials, which, by nature, are inherently inhomogeneous. While the unit cell of a metamaterial can be made considerably smaller than the free space wavelength, there remains a significant variation of the phase across the unit cell at operational frequencies in nearly all metamaterial structures reported to date. In this respect, metamaterials do not rigorously satisfy an effective medium limit and are closer conceptually to photonic crystals. Nevertheless, we show here that a modification of the standard S-parameter retrieval procedure yields physically reasonable values for the retrieved electromagnetic parameters, even when there is significant inhomogeneity within the unit cell of the structure. We thus distinguish a metamaterial regime, as opposed to the effective medium or photonic crystal regimes, in which a refractive index can be rigorously established but where the wave impedance can only be approximately defined. We present numerical simulations on typical metamaterial structures to illustrate the modified retrieval algorithm and the impact on the retrieved material parameters. We find that no changes to the standard retrieval procedures are necessary when the inhomogeneous unit cell is symmetric along the propagation axis; however, when the unit cell does not possess this symmetry, a modified procedure--in which a periodic structure is assumed--is required to obtain meaningful electromagnetic material parameters.

Journal Article↗

PubMed1985

Storage-retrieval processes of normal and learning-disabled children: a stages-of-learning analysis of picture-word effects.

Previous research comparing acquisition performance of learning-disabled and normally achieving children has led to the suggestion that the locus of memory differences lies in either the storage or retrieval components of recall. In this paper we report a free-recall experiment in which a new stages-of-learning model was used to examine the effects of a picture-word manipulation on storage and retrieval differences between nondisabled and disabled grade 2 and 6 children. Although the results of this experiment were consistent with the idea that disabled students are poorer at memory tasks than nondisabled students, the stages-of-learning analysis provided information regarding the precise locus of the deficiencies. Specifically, although disabled and nondisabled children benefited from the presentation of information in pictorial format, normally achieving children were consistently better than their learning-disabled counterparts at storing and learning to retrieve both pictures and words. From a developmental standpoint, the most important finding was that while differences between learning-disabled and normally achieving students at storage remained age invariant, differences in learning to retrieve increased with age. As it turned out, however, differences between disabled and nondisabled children were absent when it came to retaining traces once they had been stored in memory and in retrieval performance between the time a trace was stored and retrieval learning was complete. These results are consistent with previous research in which it has been shown that the ability to learn how to reliably retrieve information that has been stored in memory develops more slowly for disabled than nondisabled children.

Age Factors↗

PubMed2003

Does the use of a specialised paediatric retrieval service result in the loss of vital stabilisation skills among referring hospital staff?

AIMS: To compare the proportion of airway and vascular access procedures performed by referring hospital staff on critically ill children in two discrete time periods, before and after widespread use of a specialised paediatric retrieval service. METHODS: Transport data were obtained from retrieval logs of all children for whom a paediatric retrieval team was launched in each of two time periods (October 1993 to September 1994; and October 2000 to September 2001). RESULTS: The overall intubation rate was similar in the first and second time periods (83.9% v 79.1%). However, 31/51 (61%) retrieved children were intubated by referring hospital staff in 1993-94, compared to 227/269 (84%) in 2000-01. Referring hospital staff gained central venous access in 11% v 18% and arterial access in 22% v 19% of retrieved children in the first and second time periods respectively. This was in spite of a significant reduction in the proportion of children on whom these procedures were performed. CONCLUSION: Referring hospital staff are performing a greater proportion of initial airway and vascular access procedures undertaken in the stabilisation of sick children retrieved by a specialised paediatric retrieval team. The provision of this service has not resulted in the loss of vital skills at the local hospital.

Catheterization↗

PubMed2000

The effects of divided attention on encoding- and retrieval-related brain activity: A PET study of younger and older adults.

Divided attention (DA) disrupts episodic encoding, but has little effect on episodic retrieval. Furthermore, normal aging is associated with episodic memory impairments, and when young adults are made to encode information under DA conditions, their memory performance is reduced and resembles that of old adults working under full attention (FA) conditions. Together, these results suggest a common neurocognitive mechanism by which aging and DA during encoding disrupt memory performance. In the current study, we used PET to investigate younger and older adults' brain activity during encoding and retrieval under FA and DA conditions. In FA conditions, the old adults showed reduced activity in prefrontal regions that younger adults activated preferentially during encoding or retrieval, as well as increased activity in prefrontal regions young adults did not activate. These results indicate that prefrontal functional specificity of episodic memory is reduced by aging. During encoding, DA reduced memory performance, and reduced brain activity in left-prefrontal and medial-temporal lobe regions for both age groups, indicating that DA during encoding interferes with encoding processes that lead to better memory performance. During retrieval, memory performance and retrieval-related brain activity were relatively immune to DA for both age groups, suggesting that DA during retrieval does not interfere with the brain systems necessary for successful retrieval. Finally, left inferior prefrontal activity was reduced similarly by aging and by DA during encoding, suggesting that the behavioral correspondence between these effects is the result of a reduced ability to engage in elaborate encoding operations.

Adult↗