Media-based effects on the hydrolytic degradation and crystallization of electrospun synthetic-biologic blends

Tissue engineering scaffold degradation in aqueous environments is a widely recognized factor determining the fate of the associated anchorage-dependent cells. Electrospun blends of synthetic polycaprolactone (PCL) and a biological polymer, gelatin, of 25, 50, and 75 wt% were investigated for alterations in crystallinity, microstructure and morphology following widely used in vitro biological exposures. To our knowledge, the effects of these different aqueous-based biological media compositions on the degradation of these blends have never been directly compared. X-ray diffraction (XRD) analysis exposed that differences in PCL crystallinity were observed following exposures to phosphate buffered solution (PBS), Dulbecco’s modified eagle medium (DMEM) cell culture media, and DI water following 7 days of exposure at 37 °C. XRD data suggested that in vitro medium exposures aid in providing chain mobility and rearrangement due to hydrolytic degradation of the gelatin phase, allowing previously constrained, poorly crystalline PCL regions to achieve more intense reflections resulting in the presence of crystalline peaks. The dry, as-spun modulus of relatively soft 100 % PCL fibers was approximately 10 % of any gelatin-containing composition. Tensile testing results indicate that hydrated gelatin containing scaffolds on average had a fivefold increase in elongation compared to as-spun scaffolds. After 24-h of aqueous exposure, the elastic modulus decreased in proportion to increasing gelatin content. After 1 day of exposure, the 75 and 100 % gelatin compositions largely ceased to display measurable values of modulus, elongation or tensile strength due to considerable hydrolytic degradation. On a relative basis, common aqueous in vitro medium exposures (deionized water, PBS, and DMEM) resulted in significantly divergent amounts of crystalline PCL, overall microstructure and fiber morphology in the blended compositions, subsequently ‘shielding’ scaffolds from significant changes in mechanical properties after 24-h of exposure. Understanding electrospun PCL-gelatin scaffold dynamics in different aqueous-based cell culture medias enables the ability to tailor scaffold composition to ‘tune’ degradation rate, microstructure, and long-term mechanical stability for optimal cellular growth, proliferation, and maturation.     

The applicability of ultrasound dynamic receive beamformers to photoacoustic imaging

Ultrasound array transducers offer several advantages over mechanically-scanned transducers for photoacoustic imaging, including high imaging frame rates and dynamic focusing. Development of a photoacoustic array system can be accelerated by adapting existing commercial ultrasound systems and harnessing their performance-enhancing aspects such as parallel beamforming. One challenge faced when adapting commercial ultrasound systems for photoacoustic imaging is that the dynamic delay sequences required for focusing must account for one-way rather than two-way ultrasound wave propagation. Modifying the hardware may be difficult for developers and impossible for users, but some ultrasound systems provide a parameter, c: the speed of sound used to calculate these delays. A linear-array based ultrasound platform with parallel channel acquisition is used to compare experimental point-spread functions produced using an ultrasound beamformer with a scaled value of c to those produced by a photoacoustic beamformer. Scaling c by a factor of √2 provides the best image quality compared with adjustments by 1 and 2, but requires image rescaling, which can be done post-acquisition or by modification of the rendering software. Although optimal focusing is achieved for linear scanning, this is not the case for sector scanning, which requires angular and depth rescaling.     

Metabolomics reveals target and off-target toxicities of a model organophosphate pesticide to roach (Rutilus rutilus): implications for biomonitoring

The ability of targeted and nontargeted metabolomics to discover chronic ecotoxicological effects is largely unexplored. Fenitrothion, an organophosphate pesticide, is categorized as a "red list" pollutant, being particularly hazardous to aquatic life. It acts primarily as a cholinesterase inhibitor, but evidence suggests it can also act as an androgen receptor antagonist. Whole-organism fenitrothion-induced toxicity is well-established, but information regarding target and off-target molecular toxicities is limited. Here we study the molecular responses of male roach ( Rutilus rutilus ) exposed to fenitrothion, including environmentally realistic concentrations, for 28 days. Acetylcholine was assessed in brain; steroid metabolism was measured in testes and plasma; and NMR and mass spectrometry-based metabolomics were conducted on testes and liver to discover off-target toxicity. O-demethylation was confirmed as a major route of pesticide degradation. Fenitrothion significantly depleted acetylcholine, confirming its primary mode of action, and 11-ketotestosterone in plasma and cortisone in testes, showing disruption of steroid metabolism. Metabolomics revealed significant perturbations to the hepatic phosphagen system and previously undocumented effects on phenylalanine metabolism in liver and testes. On the basis of several unexpected molecular responses that were opposite to the anticipated acute toxicity, we propose that chronic pesticide exposure induces an adapting phenotype in roach, which may have considerable implications for interpreting molecular biomarker responses in field-sampled fish.     

Compositional changes in whole grain flours as a result of solvent washing and their effect on starch amylolysis

Whole grain flour is used most often as raw material for fuel alcohol production. However, the dry-milling process and the non-starch components of flours may impact the enzymatic hydrolysis of starch to glucose. The particle size distributions of flours prepared from whole grain triticale, barley, wheat and corn were determined and the effects of pre-washing with water, hexane, 100% ethanol or 50% ethanol on flour composition and the amylolysis of starch were studied. Scanning electron microscopy of the flours revealed that grinding grain to pass a sieve with an aperture size of 0.5 mm effectively released starch granules from endosperm cells. Pre-washing with water or 50% ethanol decreased the protein, phytic acid and total free phenolic contents of flours and, except for corn flour, increased starch content. Pre-washing with water reduced the ash contents of all flours, and reduced the ??-glucan content of barley flour by 98%. Pre-washing with hexane or 100% ethanol removed much of the lipid from the flours. Pentosan content was affected only slightly by any of the pre-washing treatments. Each of the pre-washings was associated with a significant change, positive or negative, in the extent of ??-amylolysis for one or more of the flours. The degree of ??-amylolysis in unwashed flours ranged from 22.4 to 26.1%, and from 21.6 to 28.1% in pre-washed flours, varying with flour source and solvent treatment. Pre-washing of flours increased the degree of hydrolysis achieved with sequential ??-amylase/amyloglucosidase treatment, with values ranging from 61.4 to 72.8% in pre-washed flours compared to 56.2-57.8% in unwashed flours. The highest degrees of hydrolysis were achieved with 50% ethanol pre-washing (72.4 and 72.8% for triticale and barley flours, respectively). The degree of ??-amylase/amyloglucosidase hydrolysis obtained for isolated starches ranged from 83.7 to 93.0%. This study demonstrated clearly that the partial removal of non-starch components from whole grain flours by solvent pre-washing enhanced the degree of amylolysis of starch.     

An Exploratory Examination of Student Dismissals and Prompted Resignations From Clinical Psychology PhD Training Programs: Does Clinical Competency Matter?

How do clinical psychology PhD training programs decide whether a student should be dismissed? Are these decisions related to the student's clinical competency or suitability? Accredited, scientist-practitioner clinical psychology PhD training programs were surveyed about their experiences with dismissal decisions and clinical competency evaluations. Average rates of student dismissal and prompted resignations were low (less than 3% and 6%, respectively) but highly variable across programs. The most common basis for dismissals and resignations pertained to clinical competency concerns and academic standards. However, for 29% of programs, documented dismissal criteria did not include expectations for achievement of a prescribed level of clinical skills proficiency. Implications and suggested courses of action are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal unfolding of small proteins with SH3 domain folding pattern

We have generated two conditionally immortalized neuronal cell lines from primary cultures of embryonic day 13 (E13) and postmitotic (postnatal day 0; P0) cortical neurons transformed with the temperature-sensitive SV-40 large-T antigen. Two clonal cell lines (CN1.4 from E13 cultures and SJ3.6 from P0 cultures) were isolated and stable maintained in vitro. Both cell lines expressed a number of neuronal markers such as the neurofilaments, glutamic acid decarboxylase 67, neuron-specific enolase, and the BG21 isoform of the myelin basic protein gene. At 34 degrees C, the CN1.4 cell line had elaborated short processes, whereas the SJ3.6 cell line produced long processes that formed a delicate network. When these cell lines were cultured at 39 degrees C, some of the cellular processes grew longer, adopting a more mature neuronal morphology. Interestingly, at 39 degrees C, the in vitro survival of these cell lines differed significantly. Whereas the survival of CN1.4 cell line was greatly unaffected, SJ3.6 cells died soon after they were cultured at 39 degrees C. The cell death of SJ3.6 cells was accompanied by fragmentation and condensation of DNA in their nuclei, indicative of an apoptotic event. Under these conditions, SJ3.6 showed an upregulation of the p75 receptor. When this cell line was cocultured with oligodendrocytes, astrocytes, or glial conditioned media (GCM), there was a marked increase in survival. In contrast, little effect of glial cells or GCM was observed on the CN1.4 cell line. These lines appear to be useful models to study neuronal-glial interactions in addition to neuronal cell death and the effects of glial factors that promote the survival of neurons.     

Development of a nude mouse model of ras-mediated neoplasia using WR21 cells from a transgenic mouse salivary tumor

A novel cell line (WR21) was derived from a salivary tumor in a male wap-ras transgenic mouse. Salivary tumors in wap-ras transgenic mice are extremely aggressive and express high levels of oncogenic ras protein from the activated, human Ha-ras transgene. WR21 cells also expressed high levels of oncogenic ras protein in vitro and in vivo. They gave rise to aggressive, highly anaplastic solid tumors when injected subcutaneously into athymic nude mice and approximately 90% of the mice had lung metastases by the fifth week of tumor growth. WR21 tumors were inhibited by cyclophosphamide, 5-fluorouracil, adriamycin, mitomycin C and actinomycin D, but not methotrexate. Our results suggest that the WR21/nude mice model will be useful for testing the efficacy of drug therapies against ras-mediated neoplasias.     

First record of host defence peptides in tadpoles. The magnificent tree frog Litoria splendida

We treated a 73-year-old man with a dural arteriovenous fistula (AVF) with cortical venous drainage of the left mastoid region using transarterial embolization of the middle meningeal and occipital arteries with n-butyl 2-cyanoacrylate (NBCA). The patient's clinical symptoms improved dramatically. Three months after the procedure, follow-up CT showed resolution of white matter edema and follow-up angiograms showed no evidence of a recurrent AVF. This report indicates that dural AVFs without sinus drainage can be cured solely with transarterial NBCA embolization.     

Fuzzy smoothing of HMM parameters using the Parzen window

Presents a parameter-smoothing technique for discrete hidden Markov models in speech recognition using fuzzy vector quantisation and the Parzen window. The technique is compared with existing smoothing techniques by experiments with speaker-independent isolated word recognition. The results suggest that this technique is more effective than the others in terms of improved recognition.<>