Adsorption of natural organic matter onto carbonaceous surfaces: atomic force microscopy study

The microscopic structure of carbonaceous surfaces exposed to natural organic matter (NOM) under aqueous conditions has been explored using atomic force microscopy (AFM). Dismal Swamp Water was used as the NOM source, while highly ordered pyrolytic graphite (HOPG) served as a surrogate for the graphene sheets that characterize the surface of many carbonaceous materials in aquatic environments. Under acidic conditions, the HOPG surface was covered with a densely packed monolayer of NOM molecules. In some cases, aggregates of well-defined, individual NOM molecules were observed that exhibited a degree of registry with respect to the HOPG substrate. This suggests that adsorbate-substrate interactions play a role in moderating the structure of the adsorbate layer. As the pH increased, the concentration of adsorbed NOM decreased systematically because of increasingly repulsive interactions between adsorbates. Increasing the ionic strength produced a modest increase in the concentration of adsorbed NOM. Ca2+ ions exerted a more pronounced influence on both the surface coverage of adsorbed NOM molecules and the size of individual adsorbates because of the effects of intermolecular complexation. In contrast to the spherical structures observed by AFM under aqueous conditions, adsorbed NOM formed a mixture of "ringlike" assemblies and larger aggregates upon drying.

The genome of the obligately intracellular bacterium Ehrlichia canis reveals themes of complex membrane structure and immune evasion strategies

Ehrlichia canis, a small obligately intracellular, tick-transmitted, gram-negative, alpha-proteobacterium, is the primary etiologic agent of globally distributed canine monocytic ehrlichiosis. Complete genome sequencing revealed that the E. canis genome consists of a single circular chromosome of 1,315,030 bp predicted to encode 925 proteins, 40 stable RNA species, 17 putative pseudogenes, and a substantial proportion of noncoding sequence (27%). Interesting genome features include a large set of proteins with transmembrane helices and/or signal sequences and a unique serine-threonine bias associated with the potential for O glycosylation that was prominent in proteins associated with pathogen-host interactions. Furthermore, two paralogous protein families associated with immune evasion were identified, one of which contains poly(G-C) tracts, suggesting that they may play a role in phase variation and facilitation of persistent infections. Genes associated with pathogen-host interactions were identified, including a small group encoding proteins (n = 12) with tandem repeats and another group encoding proteins with eukaryote-like ankyrin domains (n = 7).

Antisense-mediated inhibition of arginase (CAR1) gene expression in Saccharomyces cerevisiae

Inhibition of Saccharomyces cerevisiae arginase (CAR1) gene expression was investigated using the antisense RNA technique. CAR1 DNA fragments containing the yeast CAR1 gene sequences from the transcription initiation site (-49) or translation initiation site (+1) to the +501 region were amplified using PCR and inversely fused to the yeast CYC1 promoter on the yeast YIp5 plasmid. These recombinant plasmids were transformed into yeast cells to construct strains containing CYC1 promoter-antisense CAR1 DNA in their chromosomal DNA. When the CAR1 DNA region from -120 to +552 was amplified by PCR, the CYC1 promoter-antisense CAR1 DNA plasmid transformants produced the same size of PCR fragments as vector only transformants, suggesting the recombinant plasmids did not integrate into the CAR1 loci. The level of arginase production by the recombinant transformants markedly decreased to about 15% of the enzyme activity produced by the vector only transformants.

Assessment of tissue-engineered stomach derived from isolated epithelium organoid units

OBJECTIVE

Isolated stomach epithelial organoid units developed on biodegradable polymers were transplanted to assess the feasibility of a tissue-engineered stomach.

BACKGROUND

Despite recent advances in reconstruction techniques, total gastrectomy is still accompanied by various complications. An alternative treatment would be a tissue-engineered stomach, which replaces the mechanical and metabolic functions of a normal stomach.

METHODS

Stomach epithelial organoid units isolated from neonatal rats were seeded onto biodegradable polymers. The constructs implanted into the omenta of adult rats were harvested for examination at designated times. Nine rats underwent a second operation for anastomosis.

RESULTS

The constructs resulted in cyst-like formations showing vascularized tissue with neomucosa lining the lumen. The surface morphology as assessed using scanning electron microscopy was similar to that of a native stomach. Immunohistochemical staining for alpha-actin smooth muscle and gastric mucin indicated the presence of a smooth muscle layer and a well-developed gastric epithelium, respectively. The luminal surface of the anastomosed tissue-engineered stomach was well-covered with epithelium.

CONCLUSIONS

Epithelium-derived stomach organoid units seeded on biodegradable polymers and transplanted into donor rats were shown to vascularize, survive, and regenerate into complex tissue resembling native stomach. Anastomosis between the units and native small intestine may have the potential to stimulate epithelial growth. This research may provide insight into new approaches to alleviate complications following total gastrectomy.

Contractile cardiac grafts using a novel nanofibrous mesh

Cardiomyoctes are terminally differentiated cells and therefore unable to regenerate after infarction. The use of autologous bioengineered cardiac grafts has been suggested to replace infarcted myocardium and enhance cardiac function. Here we report the development of an in vitro system for engineered myocardium. Cardiac nanofibrous meshes (CNM) were developed by culturing cardiomyocytes from neonatal Lewis rats on electrospun, nanofibrous polycaprolactone (PCL) meshes. The mesh had an ECM-like topography and was suspended across a wire ring that acted as a passive load to contracting cardiomyocytes. The cardiomyocytes started beating after 3 days and were cultured in vitro for 14 days. The cardiomyocytes attached well on the PCL meshes and expressed cardiac-specific proteins such as alpha-myosin heavy chain, connexin43 and cardiac troponin I. The results demonstrate the formation of contractile cardiac grafts in vitro. Using this technique, cardiac grafts can be matured in vitro to obtain sufficient function prior to implantation. It is conjectured that cardiac grafts with clinically relevant dimensions can be obtained by stacking CNMs and inducing vascularization with angiogenic factors.

Serial follow-up study of serum testosterone and antisperm antibodies in patients with non-obstructive azoospermia after conventional or microdissection testicular sperm extraction

Testicular sperm extraction (TESE) combined with intracytoplasmic sperm injection is becoming a first-line treatment even for non-obstructive azoospermia. The current focus of TESE is the identification of seminiferous tubules that contain spermatozoa and minimization of testicular damage. Although microdissection TESE has been introduced as a preferred procedure for sperm retrieval, no serial follow-up studies of testicular damage have been reported. In the present study, we assayed serum testosterone concentrations and for the presence of antisperm antibodies (ASA) for 1 year after conventional multiple TESE or microdissection TESE and compared postoperative testicular damage between procedures. Thirteen patients who underwent conventional multiple TESE and 12 patients who underwent microdissection TESE were included in this study. Serum total and free testosterone concentrations were evaluated before operation and 1, 6 and 12 months after TESE. Serum ASA was also evaluated before and 12 months after TESE. Serum total and free testosterone concentrations in all patients in both groups showed no significant postoperative decrease. A comparison between the two groups of serum total and free testosterone concentrations showed no significant difference (total testosterone, p = 0.2477; free testosterone, p = 0.3098). No incidence of new ASA formation was identified in the present study. In conclusion, TESE procedures cause neither a decrease of serum testosterone nor formation of ASA. Serum testosterone concentration are similar between patients in the conventional multiple TESE and microdissection groups. Therefore, microdissection TESE is safe with respect to testicular damage, particularly for patients with hypogonadism.

Temporal and spatial characterization of harmonics structures of relativistic nonlinear Thomson scattering

The harmonics of the scattering of a femtosecond intense laser pulse by an electron has been numerically investigated. The harmonic spectrum shows interesting red shifts and parasitic lines in the blue sides of harmonic lines. The red shift of the lines is found to be caused by the dilation of laser oscillation experienced by an electron due to its relativistic drift motion along the direction of a driving laser propagation and the parasitic lines come from the variation of the laser intensity. The angular distribution of each higher harmonic line shows double peak patterns in the forward direction. The backward scattering has its own distinct pattern: line-shaped nodes perpendicular to the laser electric field, the number of which is the harmonic order number minus one. As the harmonic order increases, the primary peaks of higher harmonics move from the backward to the forward direction of the laser propagation. In the time domain, each radiation pulse in the case of a linearly-polarized laser pulse has a double peak structure due to the disappearance of the acceleration during the half cycle of an electron's oscillation.

Two-dimensional thick-slice MR digital subtraction angiography in the assessment of small to medium-size intracranial arteriovenous malformations

Assessment of intracranial arteriovenous malformations (AVMs) by conventional catheter angiography carries risks; moreover, this invasive procedure is often repeated for follow-up. We investigated the clinical applicability of two-dimensional thick-slice, contrast-enhanced magnetic resonance digital subtraction angiography (2D MRDSA) with high temporal resolution in the assessment of AVMs. We performed 78 2D MRDSA studies of treated or untreated small to medium-size AVMs on a 1.5 tesla imager. Two observers independently evaluated demonstration of nidus flow void on T2-weighted images and each component of the AVM on 2D MRDSA employing a three-point grading scale. In 55 patients with AVMs, the mean ratings of nidus flow voids, feeding vessels, nidi, draining vessels and early venous filling on MRI were 2.8, 2.4, 2.6, 2.8 and 2.8, respectively. sensitivity, specificity, positive and negative predictive values for an AVM using 2D MRDSA were 87, 100, 100 and 78%, respectively and for nidus flow voids on T2-weighted images 80, 91, 96 and 66%, respectively. 2D MRDSA can thus demonstrate haemodynamic features of AVMs. It can be employed as a less invasive, dynamic angiographic tool for follow-up of AVMs previously delineated by catheter angiography.

Evaluation of support materials for the surface immobilization and decoloration of amaranth by Trametes versicolor

The ability of Trametes versicolor ATCC 20869 to colonize several natural and synthetic materials (wheat straw, jute, hemp, maple woodchips, and nylon and polyethylene teraphthalate fibers) and to subsequently decolorize amaranth was evaluated. Jute was found to be the best support material as T. versicolor grew well on it without color leaching from the support and without loss of the jute's integrity over a 4 week period. The fungus immobilized on jute, straw and hemp decolorized amaranth (50 mg l(-1)) at a rate of about 5 mg l(-1) h(-1) without glucose being added. When 1 g l(-1) glucose was added, the dye was degraded more quickly (about 8 mg l(-1) h(-1)). Decoloration did not occur in a suspension culture without glucose. As the number of decoloration cycles increased, the rate of decoloration decreased. This rate was restored to its original level after the biomass was incubated in fresh growth medium for 5 days. With all immobilization supports, the toxicity of the medium before and after decoloration was the same or lower.

An inhibitor of c-jun aminoterminal kinase (SP600125) represses c-Jun activation, DNA-binding and PMA-inducible 92-kDa type IV collagenase expression

The 92-kDa type IV collagenase (MMP-9) contributes to tumor invasion and metastases and strategies to down-regulate its expression could ultimately be of clinical utility. Although the expression of this collagenase is regulated by numerous growth factors, the signaling pathways that transduce these signals are fewer in number and therefore represent pharmacological targets. In this regard, we previously reported that MMP-9 expression was regulated by the c-jun amino terminal kinase (JNK) signaling cascade. Therefore, we undertook a study to determine the efficacy of a novel compound (SP600125), which binds to the ATP binding site of all known JNKs, in repressing MMP-9 expression. In OVCAR-3 cells, SP600125 inhibited the PMA-dependent secretion of MMP-9 in a time-dependent manner and over a dose range that blocked c-Jun phosphorylation and AP-1 binding. SP600125 repressed the activity of a PMA-stimulated MMP-9 promoter-driven luciferase reporter, suggesting that diminished secretion of this collagenase reflected reduced transcription. Further, the activity of a GAL4-driven reporter in PMA-treated cells, co-transfected with an expression construct encoding the trans-activation domain of c-Jun fused to the DNA binding domain of GAL4, was repressed by SP600125. These findings indicate the efficacy of SP600125 in inhibiting c-Jun activation, DNA-binding and the PMA-dependent induction of MMP-9 expression.

An inhibitor of c-jun aminoterminal kinase (SP600125) represses c-Jun activation, DNA-binding and PMA-inducible 92-kDa type IV collagenase expression

The 92-kDa type IV collagenase (MMP-9) contributes to tumor invasion and metastases and strategies to down-regulate its expression could ultimately be of clinical utility. Although the expression of this collagenase is regulated by numerous growth factors, the signaling pathways that transduce these signals are fewer in number and therefore represent pharmacological targets. In this regard, we previously reported that MMP-9 expression was regulated by the c-jun amino terminal kinase (JNK) signaling cascade. Therefore, we undertook a study to determine the efficacy of a novel compound (SP600125), which binds to the ATP binding site of all known JNKs, in repressing MMP-9 expression. In OVCAR-3 cells, SP600125 inhibited the PMA-dependent secretion of MMP-9 in a time-dependent manner and over a dose range that blocked c-Jun phosphorylation and AP-1 binding. SP600125 repressed the activity of a PMA-stimulated MMP-9 promoter-driven luciferase reporter, suggesting that diminished secretion of this collagenase reflected reduced transcription. Further, the activity of a GAL4-driven reporter in PMA-treated cells, co-transfected with an expression construct encoding the trans-activation domain of c-Jun fused to the DNA binding domain of GAL4, was repressed by SP600125. These findings indicate the efficacy of SP600125 in inhibiting c-Jun activation, DNA-binding and the PMA-dependent induction of MMP-9 expression.

Localization in situ of specific RNA by electron microscopy

To better understand the metabolism of RNA in nuclei, the analysis of precise nuclear distribution of specific RNA would be essential. For this purpose, nonradioactive electron microscopic (EM) in situ hybridization may be the most appropriate technique while the details required for the technique have not been fully established. In the present study, we attempted to localize 28S and 18S rRNAs in the nuclei of mouse Sertoli cells by EM in situ hybridization as a model system. After various preliminary experiments we chose the pre-embedding method; fresh-frozen sections of mouse testis were fixed with a mixture of 4% paraformaldehyde and 0.1% glutaraldehyde, digested with 10 microg/ml of proteinase K and hybridized with thymine-thymine (T-T) dimerized oligodeoxynucleotides (oligo-DNA) complementary to a part of 28S and 18S rRNAs. Then, the T-T dimers were detected enzyme-immunohistochemically with horseradish peroxidase (HRP) labeled anti-T-T dimer. After osmification of HRP products, the sections were embedded in Epon resin, cut into 100 nm ultra-thin sections and observed under a transmission electron microscope. As a result, we successfully localized both 28S and 18S rRNAs in the dense fibrillar and granular components of the nucleolus, showing the usefulness of nonradioactive EM in situ hybridization in the nuclear localization of specific RNA.

Modulation of Chelidonii herba on GABA activated chloride current in rat PAG neurons

Modulation of Chelidonii herba on gamma-aminobutyric acid (GABA) activated chloride current in the acutely dissociated periaqueductal gray (PAG) neuron was studied by nystatin-perforated patch-clamp technique. High concentrations of Chelidonii herba elicited ion current, that was blocked by bicuculline. Low concentrations reduced the GABA activated current in PAG. Two types of inhibitory action of Chelidonii herba on GABA activated current have been implicated in PAG. One is the inhibitory action of Chelidonii herba on GABA was abolished by naltrexone and the other is that of Chelidonii herba was potentiated by naltrexone. In addition, all of two types of action of Chelidonii herba are linked to pertussis toxin-sensitive GTP-binding proteins. These results suggest that the inhibitory modulation of Chelidonii herba on GABA activated current via G-proteins in PAG neuron is an important analgesic mechanism.

Congestive brain oedema associated with a pial arteriovenous malformation with impaired venous drainage

We describe two patients with an unruptured pial AVM accompanied by significant brain oedema at initial presentation. In both cases, the primary drainer was a cortical vein showing varicose dilatation. in which venous congestion was indicated by magnetic resonance imaging (MRI). The restriction of venous drainage presumably caused venous hypertension in the surrounding brain, leading to the brain oedema and neurological symptoms. Brain oedema can develop in patients with an unruptured AVM by venous congestion following spontaneous thrombosis of venous components. Varicosity in a major cortical draining vein and a small nidus are the possible lesions predisposing this fairly rare condition for unruptured AVMs.

Radiation-induced apoptosis of oligodendrocytes in the adult rat brain

Although radiation injuries to the brain are well documented, immediate early histological changes in the brain remain to be defined. The present study characterizes glial injury provoked in adult rat white matter within 24 h after a single irradiation of the whole brain (10 or 20 Gray). Irradiated brains were histologically and histochemically analyzed. TUNEL-positive cells exhibiting apoptotic morphology were counted in five representative regions of the white matter. Glial cell death was further evaluated by glial cell density 24 h after irradiation, which induced both dose (p < 0.0001)- and time- (p < 0.0001) dependent apoptosis in these cells. The overall apoptotic rate in the white matter peaked within 8 h after irradiation. Total glial cell density decreased significantly in the white matter 24 h after irradiation. TUNEL-positive cells were immunohistochemically negative for GFAP, a marker for astrocytes, but positive for CNP, a marker for oligodendrocytes. The apoptotic rate was highest in the external capsule (p < 0.0001), followed by the fimbria and genu of the corpus callosum (p < 0.0001). The rates were lowest in the internal capsule and cerebellum. These data indicated that brain irradiation induces rapid apoptotic depletion of the oligodendroglial population, which may participate in the development of radiation-induced pathological conditions.