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PubMed1999

A YAC-based physical map of the mouse genome.

A physical map of the mouse genome is an essential tool for both positional cloning and genomic sequencing in this key model system for biomedical research. Indeed, the construction of a mouse physical map with markers spaced at an average interval of 300 kb is one of the stated goals of the Human Genome Project. Here we report the results of a project at the Whitehead Institute/MIT Center for Genome Research to construct such a physical map of the mouse. We built the map by screening sequenced-tagged sites (STSs) against a large-insert yeast artificial chromosome (YAC) library and then integrating the STS-content information with a dense genetic map. The integrated map shows the location of 9,787 loci, providing landmarks with an average spacing of approximately 300 kb and affording YAC coverage of approximately 92% of the mouse genome. We also report the results of a project at the MRC UK Mouse Genome Centre targeted at chromosome X. The project produced a YAC-based map containing 619 loci (with 121 loci in common with the Whitehead map and 498 additional loci), providing especially dense coverage of this sex chromosome. The YAC-based physical map directly facilitates positional cloning of mouse mutations by providing ready access to most of the genome. More generally, use of this map in addition to a newly constructed radiation hybrid (RH) map provides a comprehensive framework for mouse genomic studies.

Animals↗
PubMed1999

MAP kinase activity is downregulated by phorbol ester during mouse oocyte maturation and egg activation in vitro.

The effects of protein kinase C (PKC) stimulator, phorbol 12-myriatate 13-acetate (PMA), on meiotic cell cycle regulation and mitogen-activated protein (MAP) kinase changes have been studied in mouse oocytes and eggs. The results showed that MAP kinase activation itself was not necessary for germinal vesicle breakdown (GVBD), but the ability of the ooplasm to phosphorylate MAP kinase was a prerequisite for this event. At concentrations of 1.6 nM, PMA effectively inhibited GVBD and MAP kinase activation, suggesting that PMA inhibits GVBD by inhibiting molecule(s) upstream to MAP kinase. At concentrations of 16.2 nM, PMA induced metaphase-interphase transition more effectively in eggs collected 19 hr after human chorionic gonadotropin (hCG) administration than in those collected 15 hr after hCG administration. The degree of MAP kinase activity decrease was well correlated with the time course and proportion of pronuclear formation. On the other hand, when the effect of PMA on cell cycle progression was abolished by protein phosphatase inhibitor, okadaic acid, MAP kinase was superactivated. The biologically inactive 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD) had no evident effects on either GVBD and interphase transition or on MAP kinase activity. Furthermore, the effects of PMA on oocyte GVBD, egg activation, and MAP kinase activity could be overcome by the specific PKC inhibitor, calphostin C, suggesting the possible involvement of this enzyme in the regulation of MAP kinase activity. The results suggest that activation of PKC by PMA entrains a cascade of events that ultimately inhibits MAP kinase activation and GVBD in mouse oocytes and induces MAP kinase inactivation and metaphase-interphase transition in mouse eggs.

Animals↗
PubMed1997

Gastric inhibitory polypeptide activates MAP kinase through the wortmannin-sensitive and -insensitive pathways.

The signal transduction pathways of a cloned human gastric inhibitory polypeptide (GIP) receptor have been investigated in CHO cells stably expressing this receptor. Exposure of GIP receptor expressing cells to GIP significantly increased MAP kinase activity. Time course analysis showed that a rapid and marked increase in MAP kinase activation was detected and that this activation reached maximal levels 10 min after the addition of GIP. Dose-response analysis showed that GIP activated MAP kinase activity in a dose-dependent manner with an ED50 value of 5.9 x 10(-10) M of GIP. Wortmannin, a potent inhibitor of phosphatidylinositol 3-kinase (PI3-kinase), partially inhibited GIP-induced MAP kinase activation, suggesting that GIP activates MAP kinase through two different, wortmannin-sensitive and -insensitive pathways. It has been demonstrated that in CHO cells cAMP attenuates MAP kinase activity by inhibiting Raf-1. Since GIP elevates intracellular cAMP, we examined the effects of cAMP on MAP kinase activation. Interestingly, forskolin, which increased intracellular cAMP levels, significantly inhibited MAP kinase activation by GIP, but did not affect MAP kinase activation by GIP in the presence of wortmannin, suggesting that the wortmannin-sensitive pathway activates an MAP kinase cascade at or above the level of Raf-1 and that the wortmannin-insensitive pathway activates an MAP kinase cascade below the level of Raf-1. These findings demonstrate that the GIP receptor is linked to the MAP kinase cascade via at least two different pathways.

Androstadienes↗
PubMed1991

Dependency of microtubule-associated proteins (MAPs) for tubulin stability and assembly; use of estramustine phosphate in the study of microtubules.

Microtubule-associated proteins (MAPs) were separated from tubulin with several different methods. The ability of the isolated MAPs to reinduce assembly of phosphocellulose purified tubulin differed markedly between the different methods. MAPs isolated by addition of 0.35 M NaCl to taxol-stabilized microtubules stimulated tubulin assembly most effectively, while addition of 0.6 M NaCl produced MAPs with a substantially lower ability to stimulate tubulin assembly. The second best preparation was achieved with phosphocellulose chromatographic separation of MAPs with 0.6 M NaCl elution. The addition of estramustine phosphate to microtubules reconstituted of MAPs prepared by 0.35 M NaCl or phosphocellulose chromatography, induced less disassembly than for microtubules assembled from unseparated proteins, and was almost without effect on microtubules reconstituted from MAPs prepared by taxol and 0.6 M NaCl. Estramustine phosphate binds to the tubulin binding part of the MAPs, and the results do therefore indicate that the MAPs are altered by the separation methods. Since the MAPs are regarded as highly stable molecules, one probable alteration could be aggregation of the MAPs, as also indicated by the results. The purified tubulin itself seemed not to be affected by the phosphocellulose purification, since the microtubule proteins were unchanged by the low buffer strenght used during the cromatography. However, the assembly competence after a prolonged incubation of the microtubule proteins at 4 degrees C was dependent on intact bindings between the tubulin and MAPs.

Alkaloids↗
PubMed1992

Application and limitations of the multiple antigen peptide (MAP) system in the production and evaluation of anti-peptide and anti-protein antibodies.

The multiple antigen peptide (MAP) system has been proposed as a novel and valuable approach for eliciting antibodies to peptides and developing synthetic vaccines. The MAP system consists of a small immunogenically inert core matrix of lysine residues with alpha- and epsilon-amino groups for anchoring multiple copies of the same or different synthetic peptides. Several MAP systems, each containing eight copies of 6-15 residue-long peptides derived from the terminal and central regions of various proteins were analyzed in this study. The immunogenicity of MAPs was compared to that of the same peptides linked to carrier protein by means of conventional conjugation procedures. The various peptide antisera were tested in ELISA with homologous peptides conjugated to a carrier protein via their C terminal (as in the MAP system) or their N terminal end, or with their parent proteins. The antigenic properties of MAPs were studied with anti-peptide sera obtained by classical methods and with anti-protein sera. The results showed that the MAP system was an efficient antigen in ELISA except when the peptide corresponded to a C terminal epitope. However, the value of MAPs for raising anti-peptide antibodies cross-reactive with the cognate protein appeared much more limited. In the case of one N terminal peptide, the MAP construction was not immunogenic while the conventionally conjugated peptide induced antibodies that reacted strongly with the corresponding protein. In the case of the two C terminal peptides tested, the antibodies raised against MAP constructs reacted well with homologous MAPs but did not cross-react with the whole protein. Only in the case of a peptide from an internal domain of histone H2A did immunization with a MAP generate antibodies that cross-reacted with the protein.

Amino Acid Sequence↗
PubMed1987

An immunocytochemical analysis of the ontogeny of the microtubule-associated proteins MAP-2 and Tau in the nervous system of the rat.

The developmental distribution patterns of beta-tubulin and the microtubule-associated proteins, MAP-2 and Tau, were studied by immunocytochemistry with monoclonal antibodies. The analysis of the in situ distribution of these proteins in embryonic brain tissue revealed intense immunoreactivity for beta-tubulin in proliferative and migrating neuroblasts. On the contrary, no immunoreactivity for MAP-2 or Tau was detected in this neuroepithelium; specific immunostaining for these MAPs was only present in those neuroblasts which have reached their final destination within a developing brain area, and have initiated terminal differentiation, i.e. the sprouting of axons and dendrites. During the initial stages of neuritic outgrowth both MAPs were detected in the somatodendritic compartment of developing brain neurons; Tau was also present in axons. While the distribution of MAP-2 remained essentially the same throughout development, Tau was progressively lost from cell bodies and dendrites. This pattern of compartmentation was observed in pyramidal neurons of the cerebral cortex and hippocampus, as well as in cells of other brain regions (e.g. thalamus, hypothalamus, cerebral amygdala and tectum). It was not detected in cerebellar Purkinje cells which compartmentalize Tau to axons from the outset of neuritic differentiation, and in neurons of the Gasser ganglion which transiently express MAP-2 in axons. The expression and distribution of these MAPs was also analyzed in embryonic cerebellar and hippocampal pyramidal neurons grown in culture. Both MAPs were found in these cells as soon as 6 h after plating; they were also present in all of the neurites, axons and dendrites, that these cells extend after development in vitro for several days. With subsequence development (more than 4 days in vitro) MAP-2 was lost from axons, while Tau remained homogeneously distributed in both types of neurites. Taken collectively, the present results indicate that the development of the compartmentalized distribution of MAP-2 and Tau follows a complex pattern which is specific for each of these MAPs, and which varies as a function of the neuron type and the conditions under which the cell develops. In addition, the complex variations in the distribution of both MAPs during in situ and in vitro development make it unlikely that these proteins have a role in determining the fate of a neurite as an axon or a dendrite.

Animals↗
PubMed1994

Simultaneous 60-electrode mapping of ventricular tachycardia using percutaneous catheters.

OBJECTIVES: We developed a new approach for mapping ventricular tachycardia at electrophysiologic study using simultaneous recordings from up to 60 catheter electrodes. BACKGROUND: Good results for surgical or catheter ablation of ventricular tachycardia are limited by the ability to detect and completely map all of the underlying arrhythmogenic areas. Currently, catheter mapping of all configurations of ventricular tachycardia is impossible or unsatisfactory in at least 60% of patients because of poorly tolerated rapid rates, nonsustained ventricular tachycardia or multiple configurations. METHODS: Twenty-four patients with recurrent ventricular tachycardia refractory to antiarrhythmic drugs were studied using up to six percutaneous decapolar catheters introduced into the ventricles. Left ventricular maps of ventricular tachycardia were achieved by two to three transseptal catheters, two to three transaortic catheters, a coronary sinus catheter and right ventricular catheters. Simultaneous endocardial maps of either right or left ventricles were possible with a resolution of approximately 1 to 2 cm. Up to 60 electrograms were digitized and recorded simultaneously using a custom-computerized mapping system. RESULTS: Successful maps of 73 ventricular tachycardia configurations were obtained in 22 patients. The mapping procedure failed in two patients because of inability to catheterize the left ventricle in one and inability to induce monomorphic ventricular tachycardia in the other. The mean (+/- SD) ventricular tachycardia cycle length was 285 +/- 53 ms (range 215 to 470). A total of 39 separate arrhythmogenic areas (median 1, interquartile [25% to 75%] range 1 to 3/patient) were detected, of which 21 (54%) were in the left ventricular free wall, 17 (44%) were in the ventricular septum, and 1 (2%) was in the right ventricular outflow tract. Ten patients (45%) had at least two arrhythmogenic areas. Thirteen patients subsequently underwent operation. All but one of the arrhythmogenic areas found at surgical mapping had been identified at preoperative catheter mapping. Complications of the preoperative mapping procedure occurred in four patients, with complete resolution in three and minor long-term sequelae in the other. CONCLUSIONS: This technique permits detailed catheter mapping of all types of monomorphic ventricular tachycardias, including those leading to hemodynamic collapse, and should enable better choice and direction of surgical or catheter ablation.

Adult↗
PubMed1997

Bradykinin generation in RC-MAP during storage at 4 degrees C and leukocyte removal filtration.

We investigated contact system activation in red cell concentrate in mannitol-adenine-phosphate (MAP) solution (RC-MAP) during storage and leukocyte removal filtration. The contact system activation was assessed in terms of bradykinin (BK) generation. The BK level in the RC-MAP transiently but significantly (p < 0.05) increased at 7 to 14 days of storage. Moreover, the BK level in 21-day-stored RC-MAP was approximately 10 times higher than that in other blood components. The BK level in mannitol-containing MAP solutions, but not that in mannitol-free MAP solution, saline or whole blood, increased during storage. The plasma angiotensin-converting enzyme (ACE) activity decreased significantly only in mannitol-containing MAP solutions. These findings suggest that mannitol plays an essential role in the increase in BK level in RC-MAP. Furthermore, the BK level in RC-MAP increased 10 minutes after the start of filtration through a negatively charged filter, either a BPF-4 or an RN-40, and reached a maximum of 6,000 pg/ml. Hypotensive reactions are rare in RC-MAP transfusion in comparison to their incidence in platelet concentrate (PC) transfusion in spite of the higher BK level in RC-MAP than in PC. Therefore, BK generation in various blood components is not likely to be the main cause of hypotensive reactions. However, the level of BK in RC-MAP is sufficiently high to cause site pain. Further investigation on the clinical significance of a high BK level in blood components is necessary.

Adenine↗
PubMed2003

Comparison of detectability limits for elemental mapping by EF-TEM and STEM-XEDS.

The analytical sensitivity in terms of the signal-to-noise ratio (SNR) was investigated for elemental mapping by a transmission electron microscope equipped with an energy filter (EF-TEM) and a scanning transmission electron microscope with an X-ray energy dispersive spectrometer (STEM-XEDS). To compare the detectability limits of the elemental maps by the two techniques, homogeneous Cu-0.98+/-0.34 wt% Mn and Cu-4.93+/-0.49 wt% Mn thin specimens were used. Elemental maps can be considered as either an image or a spectrum. Therefore, the detectability limits of the elemental maps were characterized by the spectral SNR. To evaluate the detectability limits of the elemental maps with statistical confidence limits such as 1 sigma, 2 sigma and 3 sigma, the SNR values were reviewed from the statistical point of view. In STEM-XEDS mapping, the spectral SNR values improve as the specimen thickness increases since the signal intensity increases. Conversely, the spectral SNR in EF-TEM mapping is maximized at a certain thickness and then reduces as the thickness increases. To compare the two mapping techniques with regard to the analytical sensitivity, a method to estimate the minimum mass fraction (MMF) from measured signal and background intensities was developed. In this experimental approach, the MMF value can be evaluated by selecting the appropriate SNR value corresponding to the statistical confidence limits. In comparing the estimated MMF values from the two mapping approaches, EF-TEM mapping can be more sensitive than STEM-XEDS mapping up to specimen thicknesses <20-30 nm in the 1 sigma confidence limit and < approximately 50 nm in the 3 sigma limits. However, as the specimen thickness increases, the XEDS maps provide better detectability limits in the Cu-Mn dilute alloy specimens.

Journal Article↗
PubMed2000

Mapping the air in real-time to visualize the flow of gases and vapors: occupational and environmental applications.

This article describes a new method for measuring and mapping pollutants in air in real-time which can be used for visualizing the flow of gases and vapors in both indoor industrial and outdoor environmental applications. This method uses open-path Fourier Transform Infrared (OP-FTIR) spectrometry and computed tomography for real-time mapping of concentrations of chemicals in air. These maps may be used to evaluate human exposures, source emissions and air dispersion models; thus, this method can be used for both industrial and environmental sampling. It is being developed using computer simulations, and chamber and field studies. Computer simulations used simulated test concentration data to create maps; the original maps of concentrations were compared with the tomographic reconstructed maps. In the chamber studies, tracer gas was released into the chamber and measurements from a tomographic system were compared with point sample measurements taken at the same time. When sulfur hexafluoride was injected in a stable flow field position in the chamber, the concentrations reconstructed by the concentration maps were within +/- 15.9 percent of the measured point samples; overall, they were within +/- 27 percent of the measured point samples. On a 12-foot by 14-foot grid of cells used to model the chamber, the average peak location error was within one foot. The peak location error refers to the error involved in locating the point of highest concentration in the plume. For the field study, field-generated tomographic maps were compared with concentrations estimated using the Industrial Source Complex-Short Term (ISCST) model. Fairly good correlation (R2 = 0.67) was found between the five-minute overall-average cell concentrations in the tomographic and ISCST model maps. Overall, the tomographic map concentrations over-predicted the ISCST model concentrations by 24 percent. Optical remote sensing and computed tomography shows promise as a method to produce spatially and temporally resolved two-dimensional concentration maps indoors and outdoors. These maps would provide near real-time visualization of contaminant generation, movement, concentrations, and emission rates for multiple chemicals simultaneously at low limits of detection.

Air Pollution↗
PubMed2001

Map-likelihood phasing.

The recently developed technique of maximum-likelihood density modification [Terwilliger (2000), Acta Cryst. D56, 965-972] allows a calculation of phase probabilities based on the likelihood of the electron-density map to be carried out separately from the calculation of any prior phase probabilities. Here, it is shown that phase-probability distributions calculated from the map-likelihood function alone can be highly accurate and that they show minimal bias towards the phases used to initiate the calculation. Map-likelihood phase probabilities depend upon expected characteristics of the electron-density map, such as a defined solvent region and expected electron-density distributions within the solvent region and the region occupied by a macromolecule. In the simplest case, map-likelihood phase-probability distributions are largely based on the flatness of the solvent region. Though map-likelihood phases can be calculated without prior phase information, they are greatly enhanced by high-quality starting phases. This leads to the technique of prime-and-switch phasing for removing model bias. In prime-and-switch phasing, biased phases such as those from a model are used to prime or initiate map-likelihood phasing, then final phases are obtained from map-likelihood phasing alone. Map-likelihood phasing can be applied in cases with solvent content as low as 30%. Potential applications of map-likelihood phasing include unbiased phase calculation from molecular-replacement models, iterative model building, unbiased electron-density maps for cases where 2F(o) - F(c) or sigma(A)-weighted maps would currently be used, structure validation and ab initio phase determination from solvent masks, non-crystallographic symmetry or other knowledge about expected electron density.

Crystallography, X-Ray↗
PubMed2002

The Staphylococcus aureus Map protein is an immunomodulator that interferes with T cell-mediated responses.

Staphylococcus aureus (SA) is an opportunistic pathogen that affects a variety of organ systems and is responsible for many diseases worldwide. SA express an MHC class II analog protein (Map), which may potentiate SA survival by modulating host immunity. We tested this hypothesis in mice by generating Map-deficient SA (Map(-)SA) and comparing disease outcome to wild-type Map(+)SA-infected mice. Map(-)SA-infected mice presented with significantly reduced levels of arthritis, osteomyelitis, and abscess formation compared with control animals. Furthermore, Map(-)SA-infected nude mice developed arthritis and osteomyelitis to a severity similar to Map(+)SA-infected controls, suggesting that T cells can affect disease outcome following SA infection and Map may attenuate cellular immunity against SA. The capacity of Map to alter T cell function was tested more specifically in vitro and in vivo using native and recombinant forms of Map. T cells or mice treated with recombinant Map had reduced T cell proliferative responses and a significantly reduced delayed-type hypersensitivity response to challenge antigen, respectively. These data suggest a role for Map as an immunomodulatory protein that may play a role in persistent SA infections by affecting protective cellular immunity.

Adjuvants, Immunologic↗
PubMed2003

The use of interactive graphical maps for browsing medical/health Internet information resources.

As online information portals accumulate metadata descriptions of Web resources, it becomes necessary to develop effective ways for visualising and navigating the resultant huge metadata repositories as well as the different semantic relationships and attributes of described Web resources. Graphical maps provide a good method to visualise, understand and navigate a world that is too large and complex to be seen directly like the Web. Several examples of maps designed as a navigational aid for Web resources are presented in this review with an emphasis on maps of medical and health-related resources. The latter include HealthCyberMap maps http://healthcybermap.semanticweb.org/, which can be classified as conceptual information space maps, and the very abstract and geometric Visual Net maps of PubMed http://pubmed.antarcti.ca/start. Information resources can be also organised and navigated based on their geographic attributes. Some of the maps presented in this review use a Kohonen Self-Organising Map algorithm, and only HealthCyberMap uses a Geographic Information System to classify Web resource data and render the maps. Maps based on familiar metaphors taken from users' everyday life are much easier to understand. Associative and pictorial map icons that enable instant recognition and comprehension are preferred to geometric ones and are key to successful maps for browsing medical/health Internet information resources.

Journal Article↗
PubMed1999

E-MAP-115 (ensconsin) associates dynamically with microtubules in vivo and is not a physiological modulator of microtubule dynamics.

Microtubule-associated proteins (MAPs) have been hypothesized to regulate microtubule dynamics and/or functions. To test hypotheses concerning E-MAP-115 (ensconsin) function, we prepared stable cell lines expressing conjugates in which the full-length MAP (Ensc) or its microtubule-binding domain (EMTB) was conjugated to one or more green fluorescent protein (GFP) molecules. Because both distribution and microtubule-binding properties of GFP-Ensc, GFP-EMTB, and 2x, 3x, or 4xGFP-EMTB chimeras all appeared to be identical to those of endogenous E-MAP-115 (ensconsin), we used the 2xGFP-EMTB molecule as a reporter for the behavior and microtubule-binding function of endogenous MAP. Dual wavelength time-lapse fluorescence imaging of 2xGFP-EMTB in cells microinjected with labeled tubulin revealed that this GFP-MAP chimera associated with the lattice of all microtubules immediately upon polymerization and dissociated concomitant with depolymerization, suggesting that dynamics of MAP:microtubule interactions were at least as rapid as tubulin:microtubule dynamics in the polymerization reaction. Presence of both GFP-EMTB chimeras and endogenous E-MAP-115 (ensconsin) along apparently all cellular microtubules at all cell cycle stages suggested that the MAP might function in modulating stability or dynamics of microtubules, a capability shown previously in transiently transfected cells. Although cells with extremely high expression levels of GFP-EMTB chimera exhibited stabilized microtubules, cells expressing four to ten times the physiological level of endogenous MAP exhibited microtubule dynamics indistinguishable from those of untransfected cells. This result shows that E-MAP-115 (ensconsin) is unlikely to function as a microtubule stabilizer in vivo. Instead, this MAP most likely serves to modulate microtubule functions or interactions with other cytoskeletal elements.

Female↗
PubMed2003

Mussel MAP, a major gonad-duct esterase-like protein, is released into sea water as a dual constituent of the seminal fluid and the spermatozoon.

Our interest in the comparative analysis of male reproductive-tract esterases in different animal groups has led us to undertake a detailed study of the Mytilus galloprovincialis male-associated polypeptide (MAP) throughout the mussel gonad-duct tract and at spawning. The results of this work indicate that MAP is a major protein in M. galloprovincialis semen, with dual presence in both sperm cells and cell-free seminal fluid. Shortly after spawning, the released sperm mass is subdivided in diffused cloudy-like and thread-shaped 'clots', in which a soluble-phase MAP may persist as long as the clots keep their compact form. Additional experiments involving the incubation of spawned spermatozoa at increasing Triton X-100 concentrations demonstrated that MAP is also strongly associated with sperm cells. These results were further validated by immunofluorescent staining, which revealed that MAP is localized in the mid-piece region of spawned spermatozoa. This unexpected finding raises the possibility that MAP may play a role in sperm fertility in bivalves. Using whole-mount histology and micromanipulation techniques, we studied the structural patterning of the mantle gonad-duct network and assessed the sampling of luminal contents from the ducts. Of particular interest is the observation that MAP content in the luminal fluid increases from the lumen of the spermatogenic tubules to that of the collecting gonad ducts, where MAP is detected at a very high concentration. These high levels may lead to a significant presence of MAP in semen and consequently to a prolonged survival of sperm spawned at sea. In addition, data related to the potential structural similarity between mussel MAP and esterase S of the Drosophila virilis ejaculatory bulb are presented and discussed. Finally, we show that the 64kDa protein of human semen reveals positive cross-reactivity with antibodies directed against Mytilus MAP and Drosophila esterase S. Taken together, the results reveal mussel MAP as the only esterase-like protein described so far whose distribution in the gonad and semen can be specifically associated with maturation, transport, emission and survival of spermatozoa outside.

Amino Acid Sequence↗
PubMed2003

Assessment of the accuracy and safety of the different methods used in mapping the frontal sinus.

INTRODUCTION: Frontal sinus obliteration continues to be the gold standard for frontal disease control and is often employed as a last resort of treatment after more conservative therapies fail. Different methods of sinus mapping have been previously reported and include (1) 6-foot Caldwell radiography, (2) sinus probing, and (3) sinus transillumination. Image-guided technology was recently introduced to clinical practice, but its utility in frontal sinus mapping has not been evaluated. OBJECTIVE: To assess the accuracy and safety of the previously reported methods of frontal sinus mapping and compare them with image-guided mapping. STUDY DESIGN: Five cadaveric heads were used. The four mapping methods were applied to each head along five different axes of the frontal bone: 0, 45, 90, 135, and 180 degrees. The true frontal sinus margin was ascertained. Measurements were made from the true sinus limits to the margin points estimated by the four frontal sinus mapping methods. RESULTS: The image-guided mapping method provided was the most accurate when compared with the other mapping methods (p < .01). The image-guided mapping method was also the least likely to overshoot the real margin compared with the other mapping methods (p < .001). The template method was the least accurate and least safe method. CONCLUSIONS: Image-guided mapping is the most accurate and safest method of mapping the frontal sinus margins.

Cadaver↗
PubMed1999

Learning curves and certification for breast cancer lymphatic mapping.

To determine the usefulness of lymphatic mapping and SLN biopsy, two distinct aspects of the technique must be evaluated, mapping success rates and mapping accuracy. The mapping success rate simply reflects the ability to successfully map a SLN. Mapping accuracy is reflected by the false-negative rate defined as the proportion of patients with axillary metastases among those in whom the SLN is negative for disease. It is critical within each institution that these two measurements be obtained to validate the multidisciplinary collaborative effort. It seems that surgeons with appropriate training should be able to map with 85% efficiency with zero or one false-negative cases in their first 10 patients with metastatic disease. It is our recommendation that individual surgeons join together and follow an institutional (IRB approved) protocol for lymphatic mapping in which each surgeon is required to perform at least 30 procedures of SLN biopsy followed by completion axillary lymph node dissections (phase I). There are several advantages for surgeons and patients to participate in national trials as a new technique is established: 1. Patients are fully informed. 2. For those patients who have SLN biopsy followed by a CLND (phase I), there is still an added advantage in that the SLN can be scrutinized more closely resulting in more accurate staging. 3. The surgeon and the institution can be reimbursed even while the surgeon is on the learning curve. 4. It provides for good publicity for the institution. The data should be reviewed for each surgeon after completing the first 30 cases. If the aforementioned goals of 85% success with one or fewer false-negative cases is achieved, then the individual surgeon may move on to a second (phase II) mapping protocol. In phase II, a SLN biopsy is performed and a CLND is performed only if a SLN cannot be located or the SLN contains metastases. Should the aforementioned criteria not be met, then additional procedures or onsite intraoperative mentoring may be required to further evaluate the deficiencies of the mapping procedure by the surgeon or institution. Remember that failure to map may be a function of surgical skill, nuclear medicine injection methodology, or the pathologic evaluation of the SLN. Should institutional problems arise, onsite mentoring may be helpful by someone with adequate mentoring skills to troubleshoot a potential problem. The previously outlined recommendations are similar to the recently published requirements of the American Society of Breast Surgeons that recommend documentation of 30 cases or more with an 85% or higher success rate in identifying a SLN and 5% or greater false-negative rate (single false-negative SLN in the series). A national network of training centers is being established for radioguided surgery. This new technology has the potential of being applicable to 350,000 new cases of cancer diagnosed annually in the United States. Applications include breast cancer, melanoma, and other skin tumors like Merkel cell carcinoma and poorly differentiated squamous cell carcinoma, parathyroid localization, vulvar and vaginal lesions, and bone localization. This network of training centers will provide an opportunity for surgeons, nuclear medicine physicians, and pathologists to come together and learn about this new technology. Training will include didactic sessions, live surgery, and hands-on experience with animal models. The faculty will consist of leading experts from across the country. Participating centers include the H. Lee Moffitt Cancer Center and Research Institute, John Wayne Cancer Institute, and the M.D. Anderson Cancer Center. Training sites will also be available in Durham, NC; Pittsburgh, PA; Seattle, WA; Little Rock, AR; and St. Louis, MO. The network provides access to a national lymphatic mapping database (http:/(/)mapping.rad.usf.edu), participation in national trials, and web site listings (melanoma.net, or breastdoctor.com, and endocrine

Axilla↗
PubMed2005

Problems created in attenuation-corrected SPECT images by artifacts in attenuation maps: a simulation study.

UNLABELLED: The importance of accurate attenuation correction, especially for imaging of the thorax region, is widely acknowledged. Appropriate compensation methods have been developed and introduced into clinical practice. Most of these methods use attenuation maps obtained using various transmission scanning systems. However, when maps are inaccurate, the correction procedure may introduce artifacts into the final images that can be difficult to identify and might inadvertently alter diagnosis and study outcome. As a result, attenuation correction is often avoided in clinical practice. Our objective was to examine issues related to the quality of attenuation maps and the effects that map artifacts may have on attenuation-corrected emission images. METHODS: The topics that are investigated include the problem of low transmission counts, cross-talk contributions from the emission isotope, truncation of the transmission data, and methods of map reconstruction and segmentation. Examples of patient studies displaying specific problems guided our investigations, but, because truth in these studies is seldom known, analytic and Monte Carlo-simulated data were used in the analysis. Attenuation maps and final emission images were visually checked for artifacts and for the presence of perfusion defects. In addition, quantitative evaluation of map uniformity, defect visibility, and size variation was performed. RESULTS: The statistical paired-sample t test showed significant (P < 0.05) improvement of relative SD for attenuation maps reconstructed with iterative methods as compared with filtered backprojection and for maps created with higher photon fluxes. When maps with artifacts were used to correct emission data, an increase in myocardial infarct size and creation of false heart defects were observed. CONCLUSION: Our study strongly recommends that at least a visual inspection of the quality of attenuation maps be performed before their use in compensation procedures. To improve image quality, remove artifacts, and increase diagnostic confidence, attenuation maps used in the correction procedure must be accurate and free of artifacts.

Algorithms↗