On the Difference in Mechanical Behavior of Glass Bead-Filled Polyamide 12 Specimens Produced by Laser Sintering and Injection Molding

An increasing demand for additively manufactured polymer composites with optimized mechanical properties is manifesting in different industries such as aerospace, biomedical, and automotive. Laser sintering (LS) is an additive manufacturing method that has the potential to produce reinforced polymers, which can meet the stringent requirements of these industries. For the development of a commercially viable LS nylon-based composite material, previous research studies worldwide have focused on adding glass beads to the powder material with the goal to produce fully dense parts with properties more representative of injection molded (IM) thermoplastic composites. This led to the development of a commercially available glass bead-filled polyamide 12 (PA12) powder. Although this powder has been on the market for quite a while, an in-depth comparison of the mechanical behavior of laser sintered versus IM glass bead-filled PA12 is lacking. In this study, laser-sintered glass bead-filled PA12 samples were built in different orientations and compared to IM counterparts. After sample production, the mechanical performance of the produced LS and IM parts was tested and compared to evaluate the quasistatic and dynamic mechanical performance and failure mechanisms at different load levels. In addition, the glass bead-filled PA12 properties were also compared to those of standard (unfilled) LS PA12 to assess whether glass beads actually improve the mechanical performance and fatigue lifetime of the final LS samples, as suggested in literature. Results in this work present and explain the increased stiffness but decreased fatigue life of glass bead-filled polyamide parts made by LS and IM. This research can be regarded as a "benchmark" study, in which samples produced from commercially available, filled and unfilled, PA12 powder grades are compared for both LS and conventional production techniques.

Facile Fabrication of Flexible and High-Performing Thermoelectrics by Direct Laser Printing on Plastic Foil

The emerging fields of wearables and the Internet of Things introduce the need for electronics and power sources with unconventional form factors: large area, customizable shape, and flexibility. Thermoelectric (TE) generators can power those systems by converting abundant waste heat into electricity, whereas the versatility of additive manufacturing suits heterogeneous form factors. Here, additive manufacturing of high-performing flexible TEs is proposed. Maskless and large-area patterning of Bi2Te3-based films is performed by laser powder bed fusion directly on plastic foil. Mechanical interlocking allows simultaneous patterning, sintering, and attachment of the films to the substrate without using organic binders that jeopardize the final performance. Material waste could be minimized by recycling the unexposed powder. The particular microstructure of the laser-printed material renders the-otherwise brittle-Bi2Te3 films highly flexible despite their high thickness. The films survive 500 extreme-bending cycles to a 0.76 mm radius. Power factors above 1500 µW m-1K-2 and a record-low sheet resistance for flexible TEs of 0.4 Ω sq-1 are achieved, leading to unprecedented potential for power generation. This versatile fabrication route enables innovative implementations, such as cuttable arrays adapting to specific applications in self-powered sensing, and energy harvesting from unusual scenarios like human skin and curved hot surfaces.

A-18 MRI-based Post-Concussive Syndrome (PCS) Index: No Differences between Athletes and Non-Athletes

Purpose: To evaluate for differences in patients with post-concussive syndrome from sports-related versus non-sports related mTBI using a machine-learning algorithm of MRI data. Methods: For this retrospective study, we explored the MRI records of 28 Athletes (17 M, 11F) and 16 non-Athletes (6 M, 10F) with a history of concussion and clinical PCS, and 73 no concussed reference controls (26 M,47F). All subjects were between 19 and 35-years in age. The MRI studies were done in a clinical 3 T MRI scanner. MPRAGE, DTI-FA and DTI-ADC images were used to extract radiomics features from automatically segmented MRI structures of the brain. After that, the radiomic features were processed to extract the MRI-PCS Index (Qmetrics Technologies, Rochester, NY). MRI-PCS Index is an Artificial-Intelligence (AI) derived holistic evaluation of brain health that ranges from 0.0 to 1.0. The index indicates the degree of signal/structural abnormalities found in the brain tissue of a concussed subject when compared to a non-concussed subject; hence it provides an objective measurement of PCS. Results: The sports played by the athletes were mainly football, hockey, lacrosse, and soccer while non-Athletes were mainly concussed in motor vehicle accidents. Athletes MRI-PCS Index was similar to non-Athletes (0.78 vs 0.78, p = 0.89) and both indexes were very different to the reference control (MRI-PCS Index = 0.23, IQR = 0.10–0.38, p < 0.001). Conclusions: The MRI-PCS Index, an objective measurement of structural brain health, indicated that subjects that suffer from PCS present similar MRI abnormality burden regardless of whether the mTBI was related to sports injuries or other trauma.

Equine non-invasive time-lapse imaging and blastocyst development

In this study we examined the timeline of mitotic events of invitro-produced equine embryos that progressed to blastocyst stage using non-invasive time-lapse microscopy (TLM). Intracytoplasmic sperm injection (ICSI) embryos were cultured using a self-contained imaging incubator system (Miri®TL; Esco Technologies) that captured brightfield images at 5-min intervals that were then generated into video for retrospective analysis. For all embryos that progressed to the blastocyst stage, the initial event of extrusion of acellular debris preceded all first cleavages and occurred at mean (±s.e.m.) time of 20.0±1.1h after ICSI, whereas 19 of 24 embryos that did not reach the blastocyst stage demonstrated debris extrusion that occurred at 23.8±1.1h, on average 4h longer for this initial premitotic event (P<0.05). Embryos that failed to reach the blastocyst stage demonstrated a 4-h delay compared with those that reached the blastocyst stage to reach the 2-cell stage (P<0.05). All embryos that reached the blastocyst stage expressed pulsation of the blastocyst with visible expansion and contraction at approximate 10-min intervals, or five to six times per hour. Using a logit probability method, we determined that 2- and 8-cell stage embryos could reasonably predict which embryos progressed to the blastocyst stage. Together, the results indicate that TLM for equine embryo development is a dynamic tool with promise for predicting successful embryo development.

P3660Investigating the role of neutrophils and NETs in staphylococcus aureus endocarditis

Background/Introduction

Infective endocarditis (IE) remains one of the deadliest cardiac diseases. Despite optimal antibiotic and surgical treatment, still one in three patients do not survive Staphylococcus aureus (S. aureus) IE. In order to cause this disease, bacteria need to first overcome shear stress and adhere to cardiac valves. Secondly, they need be able to progress into a complex lesion. Previously, we have shown that S. aureus adheres to cardiac valves via platelets and von Willebrand factor. However, the process of progression from initial bacterial adhesion to a complex vegetation, particularly how bacteria bypass the immune system and thrive in the host environment, remains unclear.

Purpose

We aimed to determine the role of neutrophils and neutrophil extracellular traps (NETs) in IE progression using a novel mouse model.

Methods

We intravenously injected mice with S. aureus and locally stimulated the endothelium with histamine, resulting in IE lesions that originate on inflamed heart valves. After three days we determined the development of IE on the aortic valves with Gram staining and echocardiography. We investigated the presence of NETs in 14 mice by immunostaining for citrullinated histone H3 (H3Cit), extracellular DNA, and myeloperoxidase. Of these 14 mice, 9 developed endocarditis. In a separate set of experiments, we investigated the role of neutrophils in IE development by injecting a neutrophil-depleting or control antibody 24h before surgery.

Results

Echocardiography revealed real IE lesions attached on inflamed aortic valves. Mice with endocarditis had significantly (P=0.005) more detectable H3Cit (9/9) than those without (1/5). More specifically, four mice had H3Cit+ neutrophils within thrombi, indicating early NETosis. Seven mice had an extracellular H3Cit staining pattern within the thrombus. These extracellular H3Cit-positive regions were associated with DNA and myeloperoxidase, indicating the presence of a network of NETs. When we depleted neutrophils, mice developed significantly more endocarditis (7/16 vs. 1/15, P=0.03).

Conclusion

Endocarditis lesions contained NETs or neutrophils undergoing NETosis, and neutrophil depletion led to increased IE incidence. Further investigating these two players in IE could potentially provide new strategies to combat this deadly disease.

Acknowledgement/Funding

FWO SB

Gold nanostar substrates for SERS-based chemical sensing in the femtomolar regime

We report a novel approach for fabricating gold nanostar-functionalized substrates for highly sensitive surface enhanced Raman spectroscopy (SERS)-based chemical sensing. Gold nanostars immobilized on a gold substrate via a Raman silent organic tether serve as the SERS substrate, and facilitate the chemical sensing of analytes that can either be chemisorbed or physisorbed on the nanostars. Our SERS substrates are capable of detecting chemisorbed 4-mercaptobenzoic acid at a concentration as low as 10 fM with a reproducible SERS enhancement factor of 10(9), and enable the semi-quantitative multiplexed identification of analytes from mixtures in which they have been dissolved in variable stoichiometry. Most importantly, they afford the detection of physisorbed analytes, such as crystal violet, with an excellent signal-to-noise ratio, hence serving as a versatile platform for the chemical identification of in principle any molecular analyte. These characteristics make a strong case for the use of our nanostar-based SERS substrate in practical chemical sensing applications.

003. OXIDATIVE STRESS, OSMOTIC STRESS AND APOPTOTIC CHANGES: EFFECTS ON EQUINE SPERMATOZOA

Although considerable progress has been made over the past few years in liquid or frozen storage of equine spermatozoa, there remains a large inter-individual difference in the success of semen preservation for the stallion. Equine spermatozoa undergoing low-temperature storage undergo oxidative damage to membrane phospholipids, proteins and chromatin. Osmotic stress also leads to damage to the plasma membrane and alteration in sperm metabolism. Furthermore, evidence from a number of species suggests that ejaculated spermatozoa undergo apoptotic-like changes as a consequence of cryopreservation. It appears likely that these three processes are interlinked and may impact various compartments in the sperm cell via similar pathways. Therefore, an understanding of these processes and their common metabolic pathways may be important in attempts to obviate adverse affects on equine spermatozoa during storage. Further research should evaluate the molecular pathways which may represent convergence of these stresses on the sperm cell with an aim to reducing their net detrimental effect on sperm during preservation. Supported by the John P. Hughes Endowment, the UC Davis Center for Equine Health, and the National Center for Research Resources, National Institutes of Health.

Involvement of notch and RUNX pathways in human breast cancer

Abstract #6021

Background: Recent studies have demonstrated that the Notch signaling and the RUNX-mediated transcription pathways converge in mammalian hematopoiesis where they regulate proliferation and development. Evidence from in vitro experiments, mouse models and human tumors demonstrate that Notch signaling plays an oncogenic role in human breast cancer. Studies of RUNX factors involvement in human breast cancer suggest that the Core Binding Factor [CBF, a heterodimeric transcription factor composed of a RUNX DNA binding protein (RUNX1, RUNX2, or RUNX3) and a single non-DNA binding component termed CBFβ] participates in regulating the malignant phenotype of the tumor. Thus, the RUNX factors are primarily important to Notch signaling, and it seems likely that Notch:RUNX cross-talk will be important to cellular function and disease in a variety of tissue types. Here, we present our findings on cross-talk between Notch and RUNX pathways, which will lead to a better understanding of Notch and RUNX regulated transcription in breast carcinogenesis.&#x2028; Material and Methods: The expression and localization of the Notch1 NICD and RUNX2 in normal breast tissue and breast tumor were determined by immunohistochemistry on human breast tissue microarray obtained from Feist-Weiller Cancer Center. The expression profiles of Notch and RUNX were evaluated by real-time RT-PCR, Western Immunoblot, and electrophoretic mobility shift assay (EMSA).&#x2028; Results and Discussion: We found activated Notch1 and RUNX2 predominantly expressed in the cytoplasm and nucleus of cells in human normal breast tissues, respectively. However, in human breast cancer tissue samples, activated Notch1 was found in the nucleus in a high proportion of the cancer cells, while RUNX2 presence in the nucleus was much reduced and this could be due to mislocalization, over-expression or delayed degradation of the proteins. The major transcript in the breast cancer cell lines is RUNX1, but by EMSA, RUNX2 factor is the predominant biologically active and functional form of RUNX factors associated with breast cancer cell line-derived CBF. Transcript degradation and protein stability may play significant role in the regulation of RUNX factors in breast carcinogenesis. Down-regulation of CBFβ was found to affect Notch signaling in breast cancer cells and this may lead to the identification of new therapeutic targets for the successful treatment of breast cancer.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6021.

Enhancing early bladder cancer detection with fluorescence-guided endoscopic optical coherence tomography

We report an experimental study of the possibility of enhancing early bladder cancer diagnosis with fluorescence-image-guided endoscopic optical coherence tomography (OCT). After the intravesical instillation of a 10% solution of 5-aminolevulinic acid, simultaneous fluorescence imaging (excitation of 380-420 nm, emission of 620-700 nm) and OCT are performed on rat bladders to identify the photochemical and morphological changes associated with uroepithelial tumorigenesis. The preliminary results of our ex vivo study reveal that both fluorescence and OCT can identify early uroepithelial cancers, and OCT can detect precancerous lesions (e.g., hyperplasia) that fluorescence may miss. This suggests that a cystoscope combining 5-aminolevulinic acid fluorescence and OCT imaging has the potential to enhance the efficiency and sensitivity of early bladder cancer diagnosis.

Sensate radial forearm free flaps in tongue reconstruction

BACKGROUND

Successful rehabilitation after ablative surgery requires not only the reconstruction of 3-dimensional form but also the restoration of physiologic function.

OBJECTIVE

To assess sensory recovery of reinnervated radial forearm flaps used for tongue reconstruction.

PATIENTS AND METHODS

Seventeen patients, who underwent reconstruction of glossectomy defects with reinnervated radial forearm free flaps, formed the study group. Recovery of sensation was measured by both subjective and detailed objective tests 8 months after surgery. Sensory function of the flap was compared with that of the normal residual tongue or the adjacent oral mucosa and the contralateral forearm donor site.

RESULTS

All patients involved in this study had tongue defects of hemiglossectomy or greater and adjacent floor of the mouth. Sensory recovery was observed in all of the 17 patients within 8 months. Detailed sensory testing showed that median static 2-point discrimination, moving 2-point discrimination, and pressure sensitivity (1.2 cm, 0.8 cm, and 3.7 psi, respectively) were subjectively greater in the innervated forearm flaps than in the contralateral forearm donor site (2.3 cm, 1.7 cm, and 4.6 psi, respectively) (P= .064) and similar to those of the normal tongue (0.9 cm, 0.5 cm, and 3.6 psi).

CONCLUSIONS

In all modalities examined, sensate free flaps proved superior in sensory fidelity to the native forearm donor site and closely approached that of the normal tongue. Microsurgical reinnervation of flaps should be considered in tongue reconstruction.

Detection of tumorigenesis in rat bladders with optical coherence tomography

Optical coherence tomography (OCT) is a novel technique that enables noninvasive cross-sectional imaging of biological tissues. Because of its high resolution (approximately 10 microm), superior dynamic range (140 dB in our case) and up to 2-3 mm penetration depth, OCT is potentially useful for noninvasive screening of superficial lesions. Bladder cancer arises within the transitional epithelium. Despite the ability to visualize the epithelium via cystoscopy, it is often difficult to detect early epithelial cancers and to determine their penetration to the underlying layers. To investigate the potential of OCT to enhance imaging of bladder cancers and other epithelial lesions, we applied OCT to normal and diseased bladder epithelium, and correlated the results with histological findings. OCT images of porcine bladder (a close homolog of human bladder) confirm the ability of this method to image human tissues. To determine whether OCT can track the course of bladder cancer, a standard rat model of bladder cancer in which Fisher rats are exposed to methyl-nitroso-urea (MNU), was followed both with OCT and histological studies. Our results show that the micro morphology of porcine bladder such as the urothelium, submucosa and muscles is identified by OCT and well correlated with the histological evaluations. OCT detected edema, inflammatory infiltrates, and submucosal blood congestion as well as the abnormal growth of urothelium (e.g., papillary hyperplasia and carcinomas). By contrast, surface imaging, which resembles cystoscopy, provided far less sensitivity and resolution than OCT. This is the first OCT study of any tumor documented in a systematic fashion, and the results suggest the potential of OCT for the noninvasive diagnosis of both bladder inflammatory lesions and early urothelial abnormalities, which conventional cystoscopy often misses, by imaging characterization of the increases in urothelial thickening and backscattering. However, because of the depth limitation, OCT may have limited applications in staging the invasion of higher-state urothelial cancers, especially for papillary carcinomas.

ETO, a target of t(8;21) in acute leukemia, makes distinct contacts with multiple histone deacetylases and binds mSin3A through its oligomerization domain

t(8;21) and t(16;21) create two fusion proteins, AML-1-ETO and AML-1-MTG16, respectively, which fuse the AML-1 DNA binding domain to putative transcriptional corepressors, ETO and MTG16. Here, we show that distinct domains of ETO contact the mSin3A and N-CoR corepressors and define two binding sites within ETO for each of these corepressors. In addition, of eight histone deacetylases (HDACs) tested, only the class I HDACs HDAC-1, HDAC-2, and HDAC-3 bind ETO. However, these HDACs bind ETO through different domains. We also show that the murine homologue of MTG16, ETO-2, is also a transcriptional corepressor that works through a similar but distinct mechanism. Like ETO, ETO-2 interacts with N-CoR, but ETO-2 fails to bind mSin3A. Furthermore, ETO-2 binds HDAC-1, HDAC-2, and HDAC-3 but also interacts with HDAC-6 and HDAC-8. In addition, we show that expression of AML-1-ETO causes disruption of the cell cycle in the G(1) phase. Disruption of the cell cycle required the ability of AML-1-ETO to repress transcription because a mutant of AML-1-ETO, Delta469, which removes the majority of the corepressor binding sites, had no phenotype. Moreover, treatment of AML-1-ETO-expressing cells with trichostatin A, an HDAC inhibitor, restored cell cycle control. Thus, AML-1-ETO makes distinct contacts with multiple HDACs and an HDAC inhibitor biologically inactivates this fusion protein.

Alterations in subnuclear trafficking of nuclear regulatory factors in acute leukemia

The nuclear matrix plays an important role in the functional organization of the nucleus in part by locally concentrating regulatory factors involved in nucleic acid metabolism. A number of nuclear regulatory proteins initially identified due to their involvement in human cancer are localized to discrete nuclear matrix-attached foci and correct nuclear partitioning likely plays a role in their function. Two such examples are promyelocytic leukemia (PML) and acute myelogenous leukemia-1 (AML-1; Runx1). PML, the target of the t(15;17) in acute PML, is localized to PML nuclear bodies (also termed Nuclear Domain 10 and PML oncogenic domains), a nuclear matrix-associated body whose function appears to be quite complex, with probable roles in cancer, apoptosis, and in acute viral infections. In t(15;17)-containing leukemic cells, the PML nuclear bodies are disrupted, but reform when the leukemic cells are induced to differentiate in the presence of all-trans retinoic acid. AML1 (RUNX1) is a key regulator of hematopoietic differentiation and AML1 proteins are found in nuclear compartments that reflect their roles in transcriptional activation and repression. The t(8;21), associated with AML, results in a chimeric transcription factor, AML-1/ETO (eight twenty one), that remains attached to the nuclear matrix through targeting signals contained in the ETO protein. When co-expressed, ETO and AML-1/ETO co-localize to a nuclear compartment distinct from that of AML1 or PML nuclear bodies. Interestingly, enforced expression of ETO or AML-1/ETO changes the average number of PML nuclear bodies per cell. Thus, chromosomal translocations involving AML1 result in altered nuclear trafficking of the transcription factor as well as other changes to the nuclear architecture. J. Cell. Biochem. Suppl. 35:93-98, 2000.

Excimer laser facilitated percutaneous coronary intervention of a nondilatable coronary stent

A patient is described in which excimer laser percutaneous coronary intervention is performed inside a suboptimally expanded stent due to nondilatable calcified plaque. The use of excimer laser facilitated full expansion of the stent with a balloon.

Type B leukemogenic virus has a T-cell-specific enhancer that binds AML-1

Type B leukemogenic virus (TBLV) induces rapidly appearing T-cell tumors in mice. TBLV is highly related to mouse mammary tumor virus (MMTV) except that TBLV long terminal repeats (LTRs) have a deletion of negative regulatory elements and a triplication of sequences flanking the deletion. To determine if the LTR triplication represents a viral enhancer element, we inserted the triplication upstream and downstream in either orientation relative to the thymidine kinase promoter linked to the luciferase gene. These experiments showed that upregulation of reporter gene activity by the TBLV triplication was relatively orientation independent, consistent with the activity of eukaryotic enhancer elements. TBLV enhancer activity was observed in T-cell lines but not in fibroblasts, B cells, or mammary cells, suggesting that enhancer function is cell type dependent. To analyze the transcription factor binding sites that are important for TBLV enhancer function, we prepared substitution mutations in a reconstituted C3H MMTV LTR that recapitulates the deletion observed in the TBLV LTR. Transient transfections showed that a single mutation (556M) decreased TBLV enhancer activity at least 20-fold in two different T-cell lines. This mutation greatly diminished AML-1 (recently renamed RUNX1) binding in gel shift assays with a mutant oligonucleotide, whereas AML-1 binding to a wild-type TBLV oligomer was specific, as judged by competition and supershift experiments. The 556 mutation also reduced TBLV enhancer binding of two other protein complexes, called NF-A and NF-B, that did not appear to be related to c-Myb or Ets. AML-1 overexpression in a mammary cell line enhanced expression from the TBLV LTR approximately 30-fold. These data suggest that binding of AML-1 to the TBLV enhancer, likely in combination with other factors, is necessary for optimal enhancer function.

Use of dermal grafts in reconstructing deep nasal defects and shaping the ala nasi

BACKGROUND

Deep postsurgical defects on the nose and alar rim pose a challenge to repair. Several techniques are available to reestablish normal contour. If a depressed area is anticipated, dermal grafts can be used to fill the defect and soften contour irregularities. The technique is simple and can prevent the need for a more complicated repair.

OBJECTIVE

To reestablish normal contour over nasal defects by using dermal grafts as a tissue filler in conjunction with graft and flap reconstruction.

METHODS

Fifteen patients had contour deformities that could be improved with dermal graft insertion under their full-thickness skin grafts or flaps. Fourteen of these patients had nasal defects and one had a vermilion border defect that resulted from tumor removal by Mohs surgery. Patient selection, dermal graft harvesting, and surgical technique are described.

RESULTS

All patients showed cosmetic benefit from dermal grafting. Contour was improved in each case. Fourteen patients had no significant complications. One flap showed tip necrosis in a patient who was a smoker. No resorption of the dermal grafts occurred over the 1- to 9-month follow-up period. No cyst formation occurred.

CONCLUSION

Dermal grafts can be used during the initial repair of postsurgical nasal defects. These dermis grafts effectively fill the defect and restore contour. The technique is simple, easily mastered, and can obviate the need for more complicated repair.

Fine-mapping and construction of a bovine contig spanning the ovine callipyge locus

The callipyge (CLPG) gene was fine-mapped by linkage analysis to a 4.6-cM chromosome interval on distal ovine OAR18q, flanked by microsatellite markers IDVGA30 and OY3. The OAR18q linkage map and human HSA14q transcript map were aligned by genotyping two bovine-hamster whole-genome radiation hybrid panels with the microsatellite markers, as well as with sequences corresponding to HSA 14q genes. Using Type I loci mapping to the IDVGA30-OY3 interval as anchor points, we have constructed a 1.4-Mb bovine BAC contig containing the IDVGA30-OY3 interval. We demonstrate that the IDVGA30-OY3 interval spans approximately 770 kb and contains at least four genes: YY1, WARS, DLK1, and GTL2.

Construction and characterization of an ovine BAC contig spanning the callipyge locus

We describe the construction of an ovine BAC contig spanning a 4.6 centimorgan (cM) chromosome segment known to contain the callipyge (CLPG) locus. The contig comprises 21 ovine BAC clones jointly covering approximately 900 kilobases (Kb). Two gaps in the BAC contig, spanning 10 and 7.5 Kb, respectively, were bridged by long range PCR. The corresponding chromosome region was shown to be characterized by an unusually low Kb to cM ratio (164 Kb/cM) and a high density of Not1 sites (1:126 Kb) possibly reflecting a high gene density in the corresponding chromosome region. Equivalent amplification of 64 sequence tagged sites spanning the corresponding region from homozygous +/+ and CLPG/CLPG individuals disproves the hypothesis of a major deletion causing the CLPG mutation.

Nuclear import and subnuclear localization of the proto-oncoprotein ETO (MTG8)

ETO (MTG8) was first described due to its involvement in the (8;21) translocation frequently observed in acute myeloid leukemias. In the t(8;21) the AML1 gene on chromosome 21 is fused to ETO on chromosome 8. The resultant hybrid protein is comprised of the DNA binding domain of AML-1 and the majority of ETO. This study examines the subnuclear distributions of ETO, AML-1B and AML-1/ETO proteins fused to green fluorescence protein in living cells using fluorescence microscopy. Further, we identified a 40 amino acid portion of ETO (amino acids 241-280) that was sufficient to cause nuclear import of green fluorescent protein. Mutational analysis demonstrated that lysine 265 and/or arginine 266 were required for nuclear import of ETO, but that the surrounding basic residues were not critical. ETO interacted with the nuclear import proteins importin-alpha and beta in vitro, and mutations in ETO that abolish nuclear localization also abolished the in vitro interaction with importin-alpha and beta. These data suggest that ETO enters the nucleus via an importin-mediated pathway. Additionally, ETO and AML-1/ETO co-localized to punctate nuclear bodies distinct from those containing promyelocytic leukemia protein. Nuclear body formation was dependent upon a region of ETO N-terminal to the nuclear localization signal. Thus, ETO and AML-1/ETO reside in potentially novel subnuclear compartments.

Changes in cerebral blood flow and distribution associated with acute increases in plasma sodium and osmolality of chronic hyponatremic rats

The cause of the osmotic demyelination syndrome that follows too rapid correction of chronic hyponatremia (CHN) is unknown. Recently, we reported in CHN rats an association between blood-brain barrier (BBB) disruption occurring as early as 3 h into correction and subsequent demyelination. Given the changes in brain water and blood volume which occur during correction of CHN, we hypothesized that the same correction protocol that causes demyelination might alter cerebral blood flow (CBF) during correction, thereby possibly contributing to BBB disruption and demyelination. Ten CHN rats were given hypertonic sodium intraperitoneally and its effect on CBF was continuously monitored for 3 h by magnetic resonance flow imaging. Over the subsequent 3 h, plasma sodium rose from 110.8 to 127.6 mEq/liter (P < 0.001) but neither mean arterial blood pressure nor arterial CO(2) tension changed significantly. By 30 min, CBF increased by 50% in cortical and subcortical areas (P < 0.001) and remained elevated for the next 60 min. After 2 h, cortical flow was no longer elevated significantly and by 3 h it had returned to control values. Subcortical flow, however, significantly exceeded control values throughout the 3 h so that after 2 h the ratio of cortical to subcortical blood flow had fallen from 1.17 to 0.91 (P < 0.05). Although the mechanism by which increased plasma sodium and osmolality alters CBF is uncertain, the results suggest that changes in CBF may be part of a cascade of cerebrovascular disturbances including endothelial or parenchymal damage, mechanical events, metabolic disturbances, or cytokine release which eventually lead to BBB disruption and subsequent demyelination.

Use of neurotransmitter precursors for treatment of depression

Insufficient activity of the neurotransmitters serotonin and norepinephrine is a central element of the model of depression most widely held by neurobiologists today. In the late 1970s and 1980s, numerous studies were performed in which depressed patients were treated with the serotonin precursors L-tryptophan and 5-hydroxytryptophan (5-HTP), and the dopamine and norepinephrine precursors tyrosine and L-phenylalanine. This article briefly reviews the published research on the efficacy of neurotransmitter precursors in treating depression, highlights the findings of studies, and discusses issues regarding the interpretation of those findings. The nature of the studies makes it difficult to draw firm conclusions regarding the efficacy of neurotransmitter precursors for treating depression. While there is evidence that precursor loading may be of therapeutic value, particularly for the serotonin precursors 5-HTP and tryptophan, more studies of suitable design and size might lead to more conclusive results. However, the evidence suggests neurotransmitter precursors can be helpful in patients with mild or moderate depression.

Ovarian cancer: comparison of observer performance for four methods of interpreting CT scans

PURPOSE

To assess the effects of four interpretative methods on observers' mean sensitivity and specificity by using computed tomography (CT) of ovarian carcinoma as a model.

MATERIALS AND METHODS

CT scans in 98 patients with ovarian carcinoma and 49 women who were disease free were retrospectively reviewed by four experienced blinded radiologists to compare single-observer reading, single-observer reading with an anatomic checklist, paired-observer reading (simultaneous double reading), and replicated reading (combination of two independent readings). Confidence level scoring was used to identify three possible disease forms in each patient: extranodal tumor, lymphadenopathy, and ascites. Patient conditions were then categorized as abnormal or normal.

RESULTS

There were no significant improvements in sensitivity or specificity for classification of patient conditions as abnormal or normal when comparing single-observer interpretation with single-observer interpretation with a checklist or paired-observer interpretation. Although there was no significant improvement in the mean sensitivity (93% vs 94%) by using the replicated reading method, there was a statistically significant improvement in mean specificity (85% vs 79%) for the replicated readings compared with single-observer interpretations (P < .05).

CONCLUSION

Diagnostic aids such as checklists and paired simultaneous readings did not lead to an improved mean observer performance for experienced readers. However, an increase in the mean specificity occurred with replicated readings.

ETO-2, a new member of the ETO-family of nuclear proteins

The t(8;21) is associated with 12-15% of acute myelogenous leukemias of the M2 subtype. The translocation results in the fusion of two genes, AML1 (CBFA2) on chromosome 21 and ETO (MTG8) on chromosome 8. AML1 encodes a DNA binding factor; the ETO protein product is less well characterized, but is thought to be a transcription factor. Here we describe the isolation and characterization of ETO-2, a murine cDNA that encodes a new member of the ETO family of proteins. ETO-2 is 75% identical to murine ETO and shares very high sequence identities over four regions of the protein with ETO (domain I-III and zinc-finger). Northern analysis identifies ETO-2 transcripts in many of the murine tissues analysed and in the developing mouse embryo. ETO-2 is also expressed in myeloid and erythroid cell lines. We confirmed the nuclear localization of ETO-2 and demonstrated that domain III and the zinc-finger region are not required for nuclear localization. We further showed that a region within ETO, containing domain II, mediates dimerization among family members. This region is conserved in the oncoprotein AML-1/ETO. The recent identification of another ETO-like protein, myeloid translocation gene-related protein 1, together with the data presented here, demonstrates that at least three ETO proteins exist with the potential to form dimers in the cell nucleus.

Mitochondrial DNA sequencing of shed hairs and saliva on robbery caps: sensitivity and matching probabilities

Sequencing of mitochondrial DNA (mtDNA) has been used for human identification based on teeth and skeletal remains. Here, we describe an amplification system for the mtDNA control region (D-loop) suited for the analysis of shed hair, which constitutes the most common biological evidence material in forensic investigations. The success rate was over 90% when applied to evidence materials such as shed hair, saliva stains and saliva on stamps. The analysis of evidence materials collected from three similar robberies revealed the presence of mtDNA sequences identical to those of the suspects in the three crimes. The use of mtDNA control region sequences for individual identification was evaluated. The probability of identity by chance for the mtDNA types of the suspects in the robberies was found to vary between Pr = 0.017 - < 0.0017, depending on the reference population used, emphasizing the need for large population databases to obtain the appropriate estimate.

Identification of a nuclear matrix targeting signal in the leukemia and bone-related AML/CBF-alpha transcription factors

Transcription factors of the AML (core binding factor-alpha/polyoma enhancer binding protein 2) class are key transactivators of tissue-specific genes of the hematopoietic and bone lineages. Alternative splicing of the AML-1 gene results in two major AML variants, AML-1 and AML-1B. We show here that the transcriptionally active AML-1B binds to the nuclear matrix, and the inactive AML-1 does not. The association of AML-1B with the nuclear matrix is independent of DNA binding and requires a nuclear matrix targeting signal (NMTS), a 31 amino acid segment near the C terminus that is distinct from nuclear localization signals. A similar NMTS is present in AML-2 and the bone-related AML-3 transcription factors. Fusion of the AML-1B NMTS to the heterologous GAL4-(1-147) protein directs GAL4 to the nuclear matrix. Thus, the NMTS is necessary and sufficient to target the transcriptionally active AML-1B to the nuclear matrix. The loss of the C-terminal domain of AML-1B is a frequent consequence of the leukemia-related t(8;21) and t(3;21) translocations. Our results suggest this loss may be functionally linked to the modified interrelationships between nuclear structure and gene expression characteristic of cancer cells.