RESUMEN

Nodular amyloidosis (NA) is a rare type of primary localized cutaneous amyloidosis in which light chain amyloid deposits in the skin without concurrent systemic involvement. We report a challenging case of NA on the scalp, mimicking primary scarring alopecia, in a relatively young and healthy 36-year-old man. In addition to a nonspecific clinical appearance with a broad differential, NA can be a difficult diagnosis because it may require ancillary testing, such as liquid chromatography-tandem mass spectrometry to type the amyloid protein, and hematology-oncology workup to exclude systemic disease. Pathologists can highlight the importance of systemic evaluation in their reports to ensure patients receive appropriate management.

RESUMEN

Brain abscess is a rare diagnosis. Common sources of infection include direct spread from otic sources, sinuses, or oral cavities, and hematogenous spread from distant sources, including the heart and lungs. Brain abscess with cultures growing oral flora species, in rare cases, may develop from bacteria in the oral cavity entering the bloodstream and then traveling to the brain via a patent foramen ovale. This report highlights a case of brain abscess caused by Streptococcus constellatus in a middle-aged man with an undiagnosed patent foramen ovale.

RESUMEN

Testicular cancer, particularly seminoma, is associated with Down syndrome. In cognitively impaired patients, the typical presenting signs of testicular cancer may be missed, and atypical presenting features may be the only clue to the diagnosis. In this report, we present the case of a 38-year-old male who presented with extensive deep vein thrombosis in the setting of seminoma.

RESUMEN

Chronic, severe otitis media was diagnosed in four Atlantic harbor seals (Phoca vitulina concolor), three of which were stranded animals undergoing rehabilitation. All seals presented with unilateral purulent aural discharge that would intermittently recur despite prolonged topical and systemic antimicrobial therapy. Aerobic culture from aural discharge isolated multidrug-resistant organisms in all seals, including Pseudomonas aeruginosa, Staphylococcus pseudintermedius, Klebsiella pneumoniae, and/or Enterococcus faecalis. Computed tomography was used in three cases to confirm otitis media and positive contrast ear canalography was used in one case to confirm tympanic membrane rupture. Given the persistent nature of otitis, surgical intervention in the form of a total ear canal ablation and lateral bulla osteotomy (TECA-LBO) was indicated. Surgery was successful in achieving complete clinical resolution of otitis in all seals. Postoperative complications included temporary unilateral paralysis of the left nare (2/4) and a transient left ptosis (1/4). Partial to complete surgical site dehiscence occurred in all cases; however, complete healing was achieved by second intention in 60 d or less. One rehabilitated seal was fitted with a satellite tag that confirmed normal swimming and diving patterns post release. In harbor seals, TECA-LBO can be performed safely to treat persistent cases of otitis media and should be considered in cases of chronic otitis that are not responsive to medical management.

Asunto(s)

Técnicas de Ablación/veterinaria , Conducto Auditivo Externo/cirugía , Oído Medio/cirugía , Osteotomía/veterinaria , Otitis Media/veterinaria , Phoca , Animales , Infecciones Bacterianas/complicaciones , Infecciones Bacterianas/cirugía , Infecciones Bacterianas/veterinaria , Enfermedad Crónica , Otitis Media/microbiología , Otitis Media/cirugía

RESUMEN

We employ dual-probe one-dimensional (1D) femtosecond (fs)/picosecond (ps) hybrid rotational coherent anti-Stokes Raman spectroscopy (HRCARS) to investigate simultaneous temperature, pressure, and O2/N2 measurements for gas-phase diagnostics. The dual-probe HRCARS technique allows for simultaneous measurements from the time and frequency-domain. A novel approach for measuring pressure, which offers high accuracy (<1%) and precision (0.42%), is presented. The technique is first demonstrated in a chamber for a range of pressures (1-1.5 bar). This technique shows an impressive capability of resolving 1D pressure gradients arising from a N2 jet impinging on a surface, both in laminar and turbulent conditions. The technique is shown to be capable of resolving single-shot pressure gradients (0.04 bar/mm) originating from kinetic energy conversion to pressure and resolves characteristic O2/N2 structures from laminar and turbulent mixing.

RESUMEN

Lanthanide-based upconverting nanoparticles (UCNPs) are known for their remarkable ability to convert near-infrared energy into higher energy light, offering an attractive platform for construction of biological imaging probes. Here we focus on in vivo high-resolution microscopy - an application for which the opportunity to carry out excitation at low photon fluxes in non-linear regime makes UCNPs stand out among all multiphoton probes. To create biocompatible nanoparticles we employed Janus-type dendrimers as surface ligands, featuring multiple carboxylates on one 'face' of the molecule, polyethylene glycol (PEG) residues on another and Eriochrome Cyanine R dye as the core. The UCNP/Janus-dendrimers showed outstanding performance as vascular markers, allowing for depth-resolved mapping of individual capillaries in the mouse brain down to a remarkable depth of ∼1000 µm under continuous wave (CW) excitation with powers not exceeding 20 mW. Using a posteriori deconvolution, high-resolution images could be obtained even at high scanning speeds in spite of the blurring caused by the long luminescence lifetimes of the lanthanide ions. Secondly, the new UCNP/dendrimers allowed us to evaluate the feasibility of quantitative analyte imaging in vivo using a popular ratiometric UCNP-to-ligand excitation energy transfer (EET) scheme. Our results show that the ratio of UCNP emission bands, which for quantitative sensing should respond selectively to the analyte of interest, is also strongly affected by optical heterogeneities of the medium. On the other hand, the luminescence decay times of UCNPs, which are independent of the medium properties, are modulated via EET only insignificantly. As such, quantitative analyte sensing in biological tissues with UCNP-based probes still remains a challenge.

Asunto(s)

Encéfalo/irrigación sanguínea , Circulación Cerebrovascular , Dendrímeros/química , Elementos de la Serie de los Lantanoides/química , Nanopartículas/química , Animales , Transferencia de Energía , Células HeLa , Humanos , Concentración de Iones de Hidrógeno , Ligandos , Ratones , Microscopía/métodos , Fotones , Polietilenglicoles/química , Solubilidad

RESUMEN

Acoustic features of speech include various spectral and temporal cues. It is known that temporal envelope plays a critical role for speech recognition by human listeners, while automated speech recognition (ASR) heavily relies on spectral analysis. This study compared sentence-recognition scores of humans and an ASR software, Dragon, when spectral and temporal-envelope cues were manipulated in background noise. Temporal fine structure of meaningful sentences was reduced by noise or tone vocoders. Three types of background noise were introduced: a white noise, a time-reversed multi-talker noise, and a fake-formant noise. Spectral information was manipulated by changing the number of frequency channels. With a 20-dB signal-to-noise ratio (SNR) and four vocoding channels, white noise had a stronger disruptive effect than the fake-formant noise. The same observation with 22 channels was made when SNR was lowered to 0 dB. In contrast, ASR was unable to function with four vocoding channels even with a 20-dB SNR. Its performance was least affected by white noise and most affected by the fake-formant noise. Increasing the number of channels, which improved the spectral resolution, generated non-monotonic behaviors for the ASR with white noise but not with colored noise. The ASR also showed highly improved performance with tone vocoders. It is possible that fake-formant noise affected the software's performance by disrupting spectral cues, whereas white noise affected performance by compromising speech segmentation. Overall, these results suggest that human listeners and ASR utilize different listening strategies in noise.

Asunto(s)

Ruido , Acústica del Lenguaje , Percepción del Habla , Software de Reconocimiento del Habla , Adulto , Inteligencia Artificial , Femenino , Humanos , Masculino , Adulto Joven

RESUMEN

Whether screening small mammal serum during antibody production or attempting to preserve a stock of precious antibody, this protocol's western blotting method using aliquots containing nanoliter volumes of antibody will benefit researchers. Time-tested western blotting workflows allowing separation and analysis of proteins are routinely utilized in clinical and laboratory settings. The necessity for relatively large quantities of antibody is a major limitation to this universal tool. This article provides a step-by-step protocol for detecting proteins of interest with solutions containing nanoliter volumes of antibody without altering the preceding gel electrophoresis and transfer methods. Important considerations, frequently encountered problems, and means of optimizing reproducibility are discussed. Complementary diagrams, images, and videos are provided. The protocol is demonstrated using 0.3 nanoliters of anti-serum to detect fibronectin in a human foreskin fibroblast cell line. Finally, two support protocols detailing methods of extracting proteins from cultured cells are reported. Published 2019. This article is a US Government work and is in the public domain in the USA.

Asunto(s)

Anticuerpos/análisis , Western Blotting/métodos , Fibroblastos/fisiología , Animales , Línea Celular , Fibronectinas/análisis , Humanos , Microquímica , Nanotecnología , Soluciones

RESUMEN

This review describes how direct visualization of the dynamic interactions of cells with different extracellular matrix microenvironments can provide novel insights into complex biological processes. Recent studies have moved characterization of cell migration and invasion from classical 2D culture systems into 1D and 3D model systems, revealing multiple differences in mechanisms of cell adhesion, migration and signalling-even though cells in 3D can still display prominent focal adhesions. Myosin II restrains cell migration speed in 2D culture but is often essential for effective 3D migration. 3D cell migration modes can switch between lamellipodial, lobopodial and/or amoeboid depending on the local matrix environment. For example, "nuclear piston" migration can be switched off by local proteolysis, and proteolytic invadopodia can be induced by a high density of fibrillar matrix. Particularly, complex remodelling of both extracellular matrix and tissues occurs during morphogenesis. Extracellular matrix supports self-assembly of embryonic tissues, but it must also be locally actively remodelled. For example, surprisingly focal remodelling of the basement membrane occurs during branching morphogenesis-numerous tiny perforations generated by proteolysis and actomyosin contractility produce a microscopically porous, flexible basement membrane meshwork for tissue expansion. Cells extend highly active blebs or protrusions towards the surrounding mesenchyme through these perforations. Concurrently, the entire basement membrane undergoes translocation in a direction opposite to bud expansion. Underlying this slowly moving 2D basement membrane translocation are highly dynamic individual cell movements. We conclude this review by describing a variety of exciting research opportunities for discovering novel insights into cell-matrix interactions.

Asunto(s)

Membrana Basal/metabolismo , Movimiento Celular/fisiología , Matriz Extracelular/metabolismo , Morfogénesis/fisiología , Transducción de Señal/fisiología , Animales , Adhesión Celular/fisiología , Humanos

RESUMEN

We demonstrate rapid [∼mm3/(h·L)] organic ligand-free self-assembly of three-dimensional, >50 µm single-domain microassemblies containing up to 107 individual aligned nanoparticles through a scalable aqueous process. Organization and alignment of aqueous solution-dispersed nanoparticles are induced by decreasing their pH-dependent surface charge without organic ligands, which could be temperature-sensitive or infrared light absorbing. This process is exhibited by transforming both dispersed iron oxide hydroxide nanorods and lithium yttrium fluoride nanoparticles into high packing density microassemblies. The approach is generalizable to nanomaterials with pH-dependent surface charge (e.g., oxides, fluorides, and sulfides) for applications requiring long-range alignment of nanostructures as well as high packing density.

RESUMEN

Metastasis suppressor genes (MSGs) have contributed to an understanding of regulatory pathways unique to the lethal metastatic process. When re-expressed in experimental models, MSGs block cancer spread to, and colonization of distant sites without affecting primary tumor formation. Genes have been identified with expression patterns inverse to a single MSG, and found to encode functional, druggable signaling pathways. We now hypothesize that common signaling pathways mediate the effects of multiple MSGs. By gene expression profiling of human MCF7 breast carcinoma cells expressing a scrambled siRNA, or siRNAs to each of 19 validated MSGs (NME1, BRMS1, CD82, CDH1, CDH2, CDH11, CASP8, MAP2K4, MAP2K6, MAP2K7, MAPK14, GSN, ARHGDIB, AKAP12, DRG1, CD44, PEBP1, RRM1, KISS1), we identified genes whose expression was significantly opposite to at least five MSGs. Five genes were selected for further analysis: PDE5A, UGT1A, IL11RA, DNM3 and OAS1. After stable downregulation of each candidate gene in the aggressive human breast cancer cell line MDA-MB-231T, in vitro motility was significantly inhibited. Two stable clones downregulating PDE5A (phosphodiesterase 5A), an enzyme involved in the regulation of cGMP-specific signaling, exhibited no difference in cell proliferation, but reduced motility by 47 and 66 % compared to the empty vector-expressing cells (p = 0.01 and p = 0.005). In an experimental metastasis assay, two shPDE5A-MDA-MB-231T clones produced 47-62 % fewer lung metastases than shRNA-scramble expressing cells (p = 0.045 and p = 0.009 respectively). This study demonstrates that previously unrecognized genes are inversely related to the expression of multiple MSGs, contribute to aspects of metastasis, and may stand as novel therapeutic targets.

Asunto(s)

Neoplasias de la Mama/patología , Perfilación de la Expresión Génica , Metástasis de la Neoplasia/genética , Animales , Neoplasias de la Mama/genética , Línea Celular Tumoral , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 5/genética , Regulación hacia Abajo , Femenino , Humanos , Ratones , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa

RESUMEN

Pancreatic adenocarcinoma has an incidence rate nearly equal to the mortality rate and is the fourth leading cause of cancer-related death in the USA. This is largely due to late symptom onset and diagnosis. Evidence has emerged that new-onset diabetes may be a symptom caused by occult pancreatic cancer. We report the case of a middle-aged African American female who presented with hyperglycemia and persistent scapular tenderness. She was subsequently diagnosed with new-onset diabetes and metastatic pancreatic cancer confirmed by liver biopsy. She did not have diabetes or pre-diabetes in the 6 months prior to presentation. The following report will serve to emphasize the role of new-onset diabetes in certain patients as a warning sign necessitating further investigation for pancreatic cancer. New-onset diabetes associated with specific risk factors may prompt for early testing, detection and treatment of pancreatic cancer.

RESUMEN

Nm23-H1 has been identified as a metastasis suppressor gene, but its protein interactions have yet to be understood with any mechanistic clarity. In this study, we evaluated the proteomic spectrum of interactions made by Nm23-H1 in 4T1 murine breast cancer cells derived from tissue culture, primary mammary tumors, and pulmonary metastases. By this approach, we identified the actin-severing protein Gelsolin as binding partner for Nm23-H1, verifying their interaction by coimmunoprecipitation in 4T1 cells as well as in human MCF7, MDA-MB-231T, and MDA-MB-435 breast cancer cells. In Gelsolin-transfected cells, coexpression of Nm23-H1 abrogated the actin-severing activity of Gelsolin. Conversely, actin severing by Gelsolin was abrogated by RNA interference-mediated silencing of endogenous Nm23-H1. Tumor cell motility was negatively affected in parallel with Gelsolin activity, suggesting that Nm23-H1 binding inactivated the actin-depolymerizing function of Gelsolin to inhibit cell motility. Using indirect immunoflourescence to monitor complexes formed by Gelsolin and Nm23-H1 in living cells, we observed their colocalization in a perinuclear cytoplasmic compartment that was associated with the presence of disrupted actin stress fibers. In vivo analyses revealed that Gelsolin overexpression increased the metastasis of orthotopically implanted 4T1 or tail vein-injected MDA-MB-231T cells (P = 0.001 and 0.04, respectively), along with the proportion of mice with diffuse liver metastases, an effect ablated by coexpression of Nm23-H1. We observed no variation in proliferation among lung metastases. Our findings suggest a new actin-based mechanism that can suppress tumor metastasis.

Asunto(s)

Actinas/metabolismo , Movimiento Celular , Gelsolina/metabolismo , Neoplasias Hepáticas/secundario , Neoplasias Pulmonares/secundario , Neoplasias Mamarias Animales/patología , Nucleósido Difosfato Quinasas NM23/metabolismo , Animales , Apoptosis , Western Blotting , Línea Celular Tumoral , Proliferación Celular , Femenino , Técnica del Anticuerpo Fluorescente , Gelsolina/antagonistas & inhibidores , Gelsolina/genética , Regulación Neoplásica de la Expresión Génica , Humanos , Técnicas para Inmunoenzimas , Inmunoprecipitación , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Mamarias Animales/genética , Neoplasias Mamarias Animales/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Nucleósido Difosfato Quinasas NM23/antagonistas & inhibidores , Nucleósido Difosfato Quinasas NM23/genética , ARN Interferente Pequeño/genética , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción

RESUMEN

Progress in nanocrystal synthesis and self-assembly enables the formation of highly ordered superlattices. Recent studies focused on spherical particles with tunable attraction and polyhedral particles with anisotropic shape, and excluded volume repulsion, but the effects of shape on particle interaction are only starting to be exploited. Here we present a joint experimental-computational multiscale investigation of a class of highly faceted planar lanthanide fluoride nanocrystals (nanoplates, nanoplatelets). The nanoplates self-assemble into long-range ordered tilings at the liquid-air interface formed by a hexane wetting layer. Using Monte Carlo simulation, we demonstrate that their assembly can be understood from maximization of packing density only in a first approximation. Explaining the full phase behaviour requires an understanding of nanoplate-edge interactions, which originate from the atomic structure, as confirmed by density functional theory calculations. Despite the apparent simplicity in particle geometry, the combination of shape-induced entropic and edge-specific energetic effects directs the formation and stabilization of unconventional long-range ordered assemblies not attainable otherwise.

RESUMEN

We report a group of optical imaging probes, comprising upconverting lanthanide nanoparticles (UCNPs) and polyanionic dendrimers. Dendrimers with rigid cores and multiple carboxylate groups at the periphery are able to tightly bind to surfaces of UCNPs pretreated with NOBF(4), yielding stable, water-soluble, biocompatible nanomaterials. Unlike conventional linear polymers, dendrimers adhere to UCNPs by donating only a fraction of their peripheral groups to the UCNP-surface interactions. The remaining termini make up an interface between the nanoparticle and the aqueous phase, enhancing solubility and offering multiple possibilities for subsequent modification. Using optical probes as dendrimer cores makes it possible to couple the UCNPs signal to analyte-sensitive detection via UCNP-to-chromophore excitation energy transfer (EET). As an example, we demonstrate that UCNPs modified with porphyrin-dendrimers can operate as upconverting ratiometric pH nanosensors. Dendritic UCNPs possess excellent photostability, solubility, and biocompatibility, which make them directly suitable for in vivo imaging. Polyglutamic dendritic UCNPs injected in the blood of a mouse allowed mapping of the cortical vasculature down to 400 µm under the tissue surface, thus demonstrating feasibility of in vivo high-resolution two-photon microscopy with continuous wave (CW) excitation sources. Dendrimerization as a method of solubilization of UCNPs opens up numerous possibilities for use of these unique agents in biological imaging and sensing.

Asunto(s)

Dendritas/fisiología , Microscopía/métodos , Nanopartículas/química , Animales , Aniones , Materiales Biocompatibles/química , Técnicas Biosensibles , Medios de Contraste/farmacología , Concentración de Iones de Hidrógeno , Ligandos , Masculino , Ensayo de Materiales , Ratones , Ratones Endogámicos C57BL , Modelos Químicos , Nanotecnología/métodos , Péptidos/química , Polímeros/química , Porfirinas/química , Solubilidad

RESUMEN

BACKGROUND: Previous studies identified the human nonmetastatic gene 23 (NME1, hereafter Nm23-H1) as the first metastasis suppressor gene. An inverse relationship between Nm23-H1 and expression of lysophosphatidic acid receptor 1 gene (LPAR1, also known as EDG2 or hereafter LPA1) has also been reported. However, the effects of LPA1 inhibition on primary tumor size, metastasis, and metastatic dormancy have not been investigated. METHODS: The LPA1 inhibitor Debio-0719 or LPA1 short hairpinned RNA (shRNA) was used. Primary tumor size and metastasis were investigated using the 4T1 spontaneous metastasis mouse model and the MDA-MB-231T experimental metastasis mouse model (n = 13 mice per group). Proliferation and p38 intracellular signaling in tumors and cell lines were determined by immunohistochemistry and western blot to investigate the effects of LPA1 inhibition on metastatic dormancy. An analysis of variance-based two-tailed t test was used to determine a statistically significant difference between treatment groups. RESULTS: In the 4T1 spontaneous metastasis mouse model, Debio-0719 inhibited the metastasis of 4T1 cells to the liver (mean = 25.2 liver metastases per histologic section for vehicle-treated mice vs 6.8 for Debio-0719-treated mice, 73.0% reduction, P < .001) and lungs (mean = 6.37 lesions per histologic section for vehicle-treated mice vs 0.73 for Debio-0719-treated mice, 88.5% reduction, P < .001), with no effect on primary tumor size. Similar results were observed using the MDA-MB-231T experimental pulmonary metastasis mouse model. LPA1 shRNA also inhibited metastasis but did not affect primary tumor size. In 4T1 metastases, but not primary tumors, expression of the proliferative markers Ki67 and pErk was reduced by Debio-0719, and phosphorylation of the p38 stress kinase was increased, indicative of metastatic dormancy. CONCLUSION: The data identify Debio-0719 as a drug candidate with metastasis suppressor activity, inducing dormancy at secondary tumor sites.

Asunto(s)

Antineoplásicos/farmacología , Isoxazoles/farmacología , Neoplasias Hepáticas/prevención & control , Neoplasias Pulmonares/prevención & control , Neoplasias Mamarias Experimentales/tratamiento farmacológico , Neoplasias Mamarias Experimentales/patología , Propionatos/farmacología , Receptores del Ácido Lisofosfatídico/antagonistas & inhibidores , Análisis de Varianza , Animales , Western Blotting , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Femenino , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Inmunohistoquímica , Antígeno Ki-67/efectos de los fármacos , Antígeno Ki-67/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/secundario , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/secundario , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Neoplasias Mamarias Experimentales/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Nucleósido Difosfato Quinasas NM23/efectos de los fármacos , Nucleósido Difosfato Quinasas NM23/metabolismo , ARN Interferente Pequeño/farmacología , Distribución Aleatoria , Receptores del Ácido Lisofosfatídico/genética , eIF-2 Quinasa/efectos de los fármacos , eIF-2 Quinasa/metabolismo

RESUMEN

Metastatic disease is the major cause of death among cancer patients. A class of genes, named metastasis suppressors, has been described to specifically regulate the metastatic process. The metastasis suppressor genes are downregulated in the metastatic lesion compared to the primary tumor. In this review, we describe the body of research surrounding the first metastasis suppressor identified, Nm23. Nm23 overexpression in aggressive cancer cell lines reduced their metastatic potential in vivo with no significant reduction in primary tumor size. A complex mechanism of anti-metastatic action is unfolding involving several known Nm23 enzymatic activities (nucleotide diphosphate kinase, histidine kinase, and 3'-5' exonuclease), protein-protein interactions, and downstream gene regulation properties. Translational approaches involving Nm23 have progressed to the clinic. The upregulation of Nm23 expression by medroxyprogesterone acetate has been tested in a phase II trial. Other approaches with significant preclinical success include gene therapy using traditional or nanoparticle delivery, and cell permeable Nm23 protein. Recently, based on the inverse correlation of Nm23 and LPA1 expression, a LPA1 inhibitor has been shown to both inhibit metastasis and induce metastatic dormancy.

Asunto(s)

Genes Supresores de Tumor , Nucleósido Difosfato Quinasas NM23/fisiología , Metástasis de la Neoplasia/prevención & control , Animales , Humanos , Ratones , Ratones Transgénicos , Nucleósido Difosfato Quinasas NM23/genética , Receptores del Ácido Lisofosfatídico/fisiología , Transfección

RESUMEN

Recently, numerous practical and theoretical studies in evolutionary biology aim at calculating the extent to which reticulation-for example, horizontal gene transfer, hybridization, or recombination-has influenced the evolution for a set of present-day species. It has been shown that inferring the minimum number of hybridization events that is needed to simultaneously explain the evolutionary history for a set of trees is an NP-hard and also fixed-parameter tractable problem. In this article, we give a new fixed-parameter algorithm for computing the minimum number of hybridization events for when two rooted binary phylogenetic trees are given. This newly developed algorithm is based on interleaving-a technique using repeated kernelization steps that are applied throughout the exhaustive search part of a fixed-parameter algorithm. To show that our algorithm runs efficiently to be applicable to a wide range of practical problem instances, we apply it to a grass data set and highlight the significant improvements in terms of running times in comparison to an algorithm that has previously been implemented.

Asunto(s)

Algoritmos , Evolución Biológica , Biología Computacional/métodos , Hibridación Genética/genética , Modelos Genéticos , Simulación por Computador , Evolución Molecular , Factores de Tiempo

RESUMEN

INTRODUCTION: In this communication we report on a novel non-invasive methodology in utilizing "soft" energy diagnostic X-rays to indirectly activate a photo-agent utilized in photodynamic therapy (PDT): Photofrin II (Photo II) through X-ray induced luminescence from Gadolinium Oxysulfide (20 micron dimension) particles doped with Terbium: Gd_{2}O_{2}S:Tb. Photodynamic agents such as Photo II utilized in PDT possess a remarkable property to become preferentially retained within the tumor's micro-environment. Upon the photo-agent's activation through (visible light) photon absorption, the agents exert their cellular cytotoxicity through type I and type II pathways through extensive generation of reactive oxygen species (ROS); namely, singlet oxygen ^{1}O_{2}, superoxide anion O_{2}^{-}, and hydrogen peroxide H_{2}O_{2}, within the intra-tumoral environment. Unfortunately, due to shallow visible light penetration depth (∼ 2 mm to 5 mm) in tissues, the current PDT strategy has largely been restricted to the treatment of surface tumors, such as the melanomas. Additional invasive strategies through optical fibers are currently utilized in getting the visible light into the intended deep seated targets within the body for PDT. METHODS: X-ray induced visible luminescence from Gd_{2}O_{2}S:Tb particles were spectroscopically characterized, and the potential in-vitro cellular cytotoxicity of Gd_{2}O_{2}S:Tb particles on human glioblastoma cells (due to 48 Hrs Gd_{2}O_{2}S:Tb particle exposure) was screened through the MTS cellular metabolic assay. In-vitro human glioblastoma cellular exposures in presence of Photo II with Gd_{2}O_{2}S:Tb particles were performed in the dark in sterile 96 well tissue culture plates, and the corresponding changes in the metabolic activities of the glioblastoma due to 15 minutes of (diagnostic energy) X-ray exposure was determined 48 Hrs after treatment through the MTS assay. RESULTS: Severe suppression (> 90% relative to controls) in the cellular metabolic activity of human glioblastoma was measured due to the treatment of clinically relevant concentrations of 20 µg/ml Photo II, with Gd_{2}O_{2}S:Tb particles, and (120 kVp) diagnostic X-rays. Taken together, the in-vitro findings herein provide the basis for future studies in determining the safety and efficacy of this non-invasive X-ray induced luminescence strategy in activating photo-agent in deep seated tumors.

Asunto(s)

Éter de Dihematoporfirina , Metales de Tierras Raras/química , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Éter de Dihematoporfirina/química , Éter de Dihematoporfirina/farmacología , Éter de Dihematoporfirina/efectos de la radiación , Gadolinio , Humanos , Fármacos Fotosensibilizantes/química , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/efectos de la radiación