Destabilisation of complex hydrides through size effects

Nanoparticles of NaAlH4, LiAlH4 and LiBH4 were prepared by encapsulating their respective hydrides within carbon nanotubes by a wet chemical approach. The resulting confinement had a profound effect on the overall hydrogen storage properties of these hydrides, with NaAlH4 and LiAlH4 releasing hydrogen from room temperature, for example.

Conditionally immortalized white preadipocytes: a novel adipocyte model

This study describes a novel approach to generate conditionally immortalized preadipocyte cell lines from white adipose tissue (IMWAT) that can be induced to differentiate into white adipocytes even after expansion in culture. Such adipocytes express markers of white fat such as peroxisome proliferator-activated receptor gamma and aP2 but not brown fat markers, have an intact insulin signaling pathway, and express proinflammatory cytokines. They can be readily transduced with adenoviral vectors, allowing them to be used to investigate the consequences of the depletion of specific adipocyte factors using short hairpin RNA. This approach has been used to study the effect of reduced expression of the nuclear receptor corepressor receptor interacting protein 140 (RIP140), a regulator of adipocyte function. The depletion of RIP140 results in changes in metabolic gene expression that resemble those in adipose tissue of the RIP140 null mouse. Thus, IMWAT cells provide a novel model for adipocytes that are derived from preadipocytes rather than fibroblasts and provide an alternative system to primary preadipocytes for the investigation of adipocyte function.

The NCI pediatric central institutional review board (PedCIRB) initiative: Progress and impact

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NCI has developed a central IRB (PedCIRB) to review NCI-sponsored pediatric clinical trials conducted by the Children's Oncology Group (COG). COG comprises ∼200 U.S. medical institutions and protocol activation traditionally requires separate protocol review by each local IRB (LIRB) and, subsequently, a review of each protocol amendment and significant adverse event. The PedCIRB model seeks to increase patient protection by improving the expertise of protocol reviewers and making their review available to all PedCIRB participating institutions. The PedCIRB consists of experts in pediatric oncology, pediatric medicine, nursing, pharmacy, bioethics, biostatistics, as well as patient advocates and childhood cancer survivors. The PedCIRB model also eliminates redundant reviews, reduces administrative burdens on local COG investigators and LIRBs, and can accelerate the pace of local protocol activation, thus increasing the availability of clinical trials to children with cancer. The PedCIRB conducts a full board protocol review that is available via a confidential website to participating LIRBs. LIRBs can choose to perform a facilitated review, using PedCIRB materials, that focuses on local concerns, rather than a full LIRB protocol review. If the LIRB accepts the PedCIRB review, the PedCIRB becomes the IRB of record for that protocol and takes responsibility for the review of subsequent protocol amendments, adverse events and continuing reviews. Since starting in November 2004, the PedCIRB has reviewed 59 protocols. Initial reviews resulted in 44 approvals pending modification and 15 protocols being tabled for further information. The time from protocol submission to final approval by the PedCIRB has ranged from 3 to 28 weeks with an average time of 16.9 weeks during year one and 12.7 weeks during year two of the project. As of November 2006, 117 of a possible 197 U.S. COG institutions (59%) have signed on to the PedCIRB initiative and 70% of the participating institutions have conducted facilitated reviews (total 750) for the 30 protocols available on the PedCIRB website. The PedCIRB's influence on protocol development and patient accrual timelines will be discussed.

No significant financial relationships to disclose.

The nuclear receptor co-repressor RIP140 controls the expression of metabolic gene networks

NRs (nuclear receptors) regulate the expression of specific gene networks in target cells by recruiting cofactor complexes involved in chromatin remodelling and in the assembly of transcription complexes. The importance of activating gene expression, in metabolic tissues, is well established, but the contribution of transcriptional inhibition is less well defined. In this review, we highlight a crucial role for RIP140 (receptor-interacting protein 140), a transcriptional co-repressor for NR, in the regulation of metabolic gene expression. Many genes involved in lipid and carbohydrate metabolism are repressed by RIP140 in adipose and muscle. The repressive function of RIP140 results from its ability to bridge NRs to repressive enzyme complexes that modify DNA and histones. In the absence of RIP140, expression from many metabolic genes is increased so that mice exhibit a lean phenotype and resistance to high-fat-diet-induced obesity and display increased glucose tolerance and insulin sensitivity. We propose that a functional interplay between transcriptional activators and the co-repressor RIP140 is an essential process in metabolic regulation.

How does auxin enhance cell elongation? Roles of auxin-binding proteins and potassium channels in growth control

Elongation growth and a several other phenomena in plant development are controlled by the plant hormone auxin. A number of recent discoveries shed light on one of the classical problems of plant physiology: the perception of the auxin signal. Two types of auxin receptors are currently known: the AFB/TIR family of F box proteins and ABP1. ABP1 appears to control membrane transport processes (H+ secretion, osmotic adjustment) while the TIR/AFBs have a role in auxin-induced gene expression. Models are proposed to explain how membrane transport (e.g., K+ and H+ fluxes) can act as a cross-linker for the control of more complex auxin responses such as the classical stimulation of cell elongation.

A comparison of two methods of analog-to-digital medical video conversion

The purpose of this study was to compare 2 methods of analog-to-digital video conversion in anticipation of improving, refining, and standardizing digital video production for medical education, diagnosis support, and telemedicine. A video workstation was devised containing 2 analog-to-digital video conversion systems: a digital video media converter with fire wire card and a video capture card. A procedure for final digital video production was created that used equivalent compression, pixel resolution, frame rate, and data rate for both systems. A subjective test was performed in which 12 archived analog videotapes, consisting of magnetic resonance angiograms, ultrasounds, neurosurgeries, and telemedicine applications, were converted digitally using the 2 methods. Randomized side by side video comparisons were analyzed and rated by subjective quality. An objective test was performed by videotaping a gray-scale test pattern off a computer monitor, digitally converting it by the 2 methods, and comparing the gray-scale values to the original pattern. There was no significant difference in overall video quality (P = .31) or grayscale reproduction using the 2 methods of analog-to-digital conversion. When performing simple analog-to-digital video conversion, a video capture card is equal in quality and costs less than a digital video (DV) media converter or fire wire card. If a digital video camera is available for use, then a DV media converter or fire wire card is more advantageous because it enables full operation of the digital video camera.

Effectiveness of multidrug therapy in multibacillary leprosy: a long-term follow-up of 34 multibacillary leprosy patients treated with multidrug regimens till skin smear negativity

The World Health Organization (WHO) Field Trials of multidrug therapy (MDT) started at Schieffelin Leprosy Research and Training Centre (SLR & IC), Karigiri, India in December 1981. The patients were treated with two MDT regimens. The first (regimen A) consisted of 600mg rifampicin and 300mg of clofazimine given under supervision on 2 consecutive days monthly, 225mg injection of acedapsone bimonthly and dapsone 100mg daily. The second regimen (regimen B) was the conventional MDT (WHO/MDT), rifampicin 600mg and clofazimine 300mg supervised once a month, dapsone 100mg and clofazimine 50mg daily, unsupervised. Both the regimens were administered for a minimum period of 2 years or until skin smear negativity, whichever occurred later. Thirty-four newly detected previously untreated MB patients, 16 of whom received regimen A and 18 regimen B, were reassessed. Both regimens were well accepted and well tolerated by the patients. Clofazimine discolouration was the only adverse effect of MDT seen in these patients. After completion of treatment with MDT, the patients were followed up for a total duration of 466 person-years with a mean of 13.7 +/- 1.4 years per patient. No relapse was seen.

Regulated expression of signal transducer and activator of transcription, Stat5, and its enhancement of PRL expression in human endometrial stromal cells in vitro

Differentiation of human endometrium during the secretory phase of the menstrual cycle is characterized by expression of a variety of genes implicated in the establishment and maintenance of pregnancy. An increased abundance of signal transducers and activators of transcription (Stats) in the secretory phase suggests Stat5 as a component of the differentiation of endometrium in response to ovarian hormone stimulation in vivo. Decidualization is initiated in a subset of endometrial stromal cells (ESC) in vivo during the secretory phase, but it is unclear whether regulated expression of Stat5 is a feature of these cells. Here, therefore, the abundance and subcellular distribution of Stat5 in ESC after a decidualization stimulus of cAMP plus medroxyprogesterone acetate (MPA) has been investigated in vitro. Western blotting revealed an increase in the apparent abundance of Stat5a and Stat5b, in the cytosolic and nuclear fractions, at 2, 3, and 4 d after stimulation. The potential functional relevance of this increase in Stat5 is suggested by the ability of transiently transfected Stat5a or Stat5b to significantly enhance the response of the decidual PRL promoter to cAMP/MPA and attenuation of the response to cAMP/MPA by dominant negative Stat5. Recent evidence suggests endometrial differentiation, including PRL production, as a possible target of antiphospholipid antibodies (aPL) prevalent in recurrent miscarriage. Monoclonal antibody, ID2, which has similar reactivity as human aPL, significantly decreased the apparent abundance of nuclear Stat5b in response to cAMP/MPA and was associated with decreased decidual PRL promoter activation and PRL secretion. Regulated expression of Stat5 is therefore a component of decidual differentiation of human ESC and contributes significantly to activation of the decidual PRL promoter. Alteration of this process by an aPL component suggests decidual differentiation as a potential clinical target in recurrent early miscarriages.

Retrotransposons of the Tnt1B family are mobile in Nicotiana plumbaginifolia and can induce alternative splicing of the host gene upon insertion

Active retrotransposons have been identified in Nicotiana plumbaginifolia by their ability to disrupt the nitrate reductase gene in chlorate-resistant mutants selected from protoplast-derived cultures. In mutants E23 and F97, two independent insertions of Tnp2, a new retrotransposon closely related to the tobacco Tnt1 elements, were detected in the nitrate reductase gene. These two Tnp2 elements are members of the Tnt1B subfamily which shows that Tnt1B elements can be active and mutagenic in the N. plumbaginifolia genome. Furthermore, these results suggest that Tnt1B is the most active family of Tntl elements in N. plumbaginifolia, whereas in tobacco only members of the Tnt1A subfamily were found inserted in the nitrate reductase gene. The transcriptional regulations of Tnp2 and Tnt1A elements are most probably different due to non-conserved U3 regions. Our results thus support the hypothesis that different Nicotiana species contain different active Tntl subfamilies and that only one active Tntl subfamily might be maintained in each of these species. The Tnp2 insertion found in the F97 mutant was found to be spliced out of the nitrate reductase mRNA by activation of cryptic donor and acceptor sites in the nitrate reductase and the Tnp2 sequences respectively.

The auxin signal for protoplast swelling is perceived by extracellular ABP1

Protoplasts of corn coleoptiles and Arabidopsis hypocotyls respond to the plant hormone auxin with a rapid change in volume. We checked the effect of antibodies directed against epitopes of auxin-binding protein 1 from Arabidopsis thaliana (AtERabp1) and Zea mays (ZmERabp1), respectively. Antibodies raised against the C-terminus of AtERabp1 inhibited the response to auxin, while antibodies raised against a part of box a, the putative auxin-binding domain, induced a swelling response similar to that caused by auxin treatment. Synthetic C-terminal oligopeptides of ZmERabp1 also caused a swelling response. These effects occurred regardless of whether the experiments were carried out with homologous (anti-AtERabp1 antibodies on Arabidopsis protoplasts or anti-ZmERabp1 antibodies in maize protoplasts) or heterologous immunological tools. The results indicate that the auxin signal for protoplast swelling is perceived by extracellular ABP1.

Interferon-gamma modulates prolactin and tissue factor expression in differentiating human endometrial stromal cells

Cytokines such as interferon-gamma (IFNgamma) released by resident uterine immune cells are thought to influence the expression of differentiated function in the human endometrium. Decidualization of the stromal cell compartment is confined to the superficial endometrial layer in the nonpregnant uterus. To explore the molecular mechanism underlying the spatial expression of the decidual phenotype, the effect of IFNgamma on the induction of two well characterized markers of endometrial stromal (ES) cell differentiation, PRL and tissue factor (TF), has been investigated. IFNgamma antagonizes cAMP-mediated PRL protein and messenger RNA expression in primary ES cell cultures through inhibition of decidual PRL promoter activity. In parallel, IFNgamma stimulates Stat-1 (signal transducer and activator of transcription-1) expression, phosphorylation, and translocation to the nucleus. Exogenously expressed Stat-1 potently represses decidual PRL promoter activation, indicating the potential for the inhibitory effects of IFNgamma to be mediated by Stat-1. We demonstrate that although the coactivator CREB-binding protein/p300 is essential for decidual PRL transcription, this coactivator does not appear to be the target for IFNgamma-mediated repression. By contrast, IFNgamma has little effect on cAMP-mediated TF expression, but induces TF in ES cells not exposed to a decidualizing stimulus. This suggested that in vivo TF expression may not be restricted to decidualizing cells of the superficial layer and was confirmed by immunohistochemical analysis demonstrating intense TF staining in the basal stromal compartment during the regeneration phase of the cycle. The differential sensitivity of decidualization-associated genes to IFNgamma illustrates its potential role as a selective biological response modifier that influences regional function within the endometrium.

Relationships between drug activity in NCI preclinical in vitro and in vivo models and early clinical trials

An analysis of the activity of compounds tested in pre-clinical in vivo and in vitro assays by the National Cancer Institute's Developmental Therapeutics Program was performed. For 39 agents with both xenograft data and Phase II clinical trials results available, in vivo activity in a particular histology in a tumour model did not closely correlate with activity in the same human cancer histology, casting doubt on the correspondence of the pre-clinical models to clinical results. However, for compounds with in vivo activity in at least one-third of tested xenograft models, there was correlation with ultimate activity in at least some Phase II trials. Thus, an efficient means of predicting activity in vivo models remains desirable for compounds with anti-proliferative activity in vitro. For 564 compounds tested in the hollow fibre assay which were also tested against in vivo tumour models, the likelihood of finding xenograft activity in at least one-third of the in vivo models tested rose with increasing intraperitoneal hollow fibre activity, from 8% for all compounds tested to 20% in agents with evidence of response in more than 6 intraperitoneal fibres (P< 0.0001). Intraperitoneal hollow fibre activity was also found to be a better predictor of xenograft activity than either subcutaneous hollow fibre activity or intraperitoneal plus subcutaneous activity combined. Since hollow fibre activity was a useful indicator of potential in vivo response, correlates with hollow fibre activity were examined for 2304 compounds tested in both the NCI 60 cell line in vitro cancer drug screen and hollow fibre assay. A positive correlation was found for histologic selectivity between in vitro and hollow fibre responses. The most striking correlation was between potency in the 60 cell line screen and hollow fibre activity; 56% of compounds with mean 50% growth inhibition below 10^–7.5 M were active in more than 6 intraperitoneal fibres whereas only 4% of compounds with a potency of 10^–4 M achieved the same level of hollow fibre activity (P< 0.0001). Structural parameters of the drugs analysed included compound molecular weight and hydrogen-bonding factors, both of which were found to be predictive of hollow fibre activity. © 2001 Cancer Research Campaign www.bjcancer.com

Electrical stimulation for swallowing disorders caused by stroke

BACKGROUND

An estimated 15 million adults in the United States are affected by dysphagia (difficulty swallowing). Severe dysphagia predisposes to medical complications such as aspiration pneumonia, bronchospasm, dehydration, malnutrition, and asphyxia. These can cause death or increased health care costs from increased severity of illness and prolonged length of stay. Existing modalities for treating dysphagia are generally ineffective, and at best it may take weeks to months to show improvement. One common conventional therapy, application of cold stimulus to the base of the anterior faucial arch, has been reported to be somewhat effective. We describe an alternative treatment consisting of transcutaneous electrical stimulation (ES) applied through electrodes placed on the neck.

OBJECTIVE

Compare the effectiveness of ES treatment to thermal-tactile stimulation (TS) treatment in patients with dysphagia caused by stroke and assess the safety of the technique.

METHODS

In this controlled study, stroke patients with swallowing disorder were alternately assigned to one of the two treatment groups (TS or ES). Entry criteria included a primary diagnosis of stroke and confirmation of swallowing disorder by modified barium swallow (MBS). TS consisted of touching the base of the anterior faucial arch with a metal probe chilled by immersion in ice. ES was administered with a modified hand-held battery-powered electrical stimulator connected to a pair of electrodes positioned on the neck. Daily treatments of TS or ES lasted 1 hour. Swallow function before and after the treatment regimen was scored from 0 (aspirates own saliva) to 6 (normal swallow) based on substances the patients could swallow during a modified barium swallow. Demographic data were compared with the test and Fisher exact test. Swallow scores were compared with the Mann-Whitney U test and Wilcoxon signed-rank test.

RESULTS

The treatment groups were of similar age and gender (p > 0.27), co-morbid conditions (p = 0.0044), and initial swallow score (p = 0.74). Both treatment groups showed improvement in swallow score, but the final swallow scores were higher in the ES group (p > 0.0001). In addition, 98% of ES patients showed some improvement, whereas 27% of TS patients remained at initial swallow score and 11% got worse. These results are based on similar numbers of treatments (average of 5.5 for ES and 6.0 for TS, p = 0.36).

CONCLUSIONS

ES appears to be a safe and effective treatment for dysphagia due to stroke and results in better swallow function than conventional TS treatment.