Modular electromagnetic railgun accelerator for high velocity impact studies.

A modular electromagnetic railgun accelerator facility named "RAFTAR" (i.e., Railgun Accelerator Facility for Technology and Research) has been commissioned and its performance has been characterized for high velocity impact testing on materials in a single-shot mode. In the first tests, RAFTAR demonstrated an acceleration of more than 1000 m/s for an 8 g solid aluminum-7075 armature projectile. The current fed was 220 kA, having a muzzle time of about 1.75 ms. It is a single pulse breech-fed rectangular bore (14 × 13 mm2) railgun, and its 1.15 m long barrel assembly consists of two parallel copper bars with an inter-gap of 13 mm that are encased within 50 mm thick high strength reinforced fiberglass sheets (Garolite G10-FR4) and bolted from both the sides. RAFTAR is powered by two capacitor bank modules that have a maximum stored energy of 160 kJ each (containing eight 178 µF/15 kV capacitors), two high power ignitron switches, and a pulse shaping inductor. To obtain consistent acceleration of the armature inside the barrel, reversal of driving current is prevented, and its pulse duration is stretched by tactical integration of the crowbar switch and bitter coil inductor in the circuit. Armature projectile velocity measurement in-bore and outside in free space was performed by the time-of-flight technique using indigenously made miniature B-dot sensors and a novel shorting-foil arrangement, respectively. The time resolved measurement of the in-bore armature evidenced a velocity-skin-effect in the high acceleration phase. There is good agreement between the experimentally measured and theoretically predicted efficiency, confirming the optimal choice of operating parameters. The conclusion summarizes important experimental findings and analyzes the underlying causes that limit the performance of railguns.

Fulminant descending mediastinitis secondary to infectious mononucleosis.

Descending mediastinitis is a rare, life-threatening condition caused by contiguous spread of oropharyngeal or cervical infection into the mediastinum. Infectious mononucleosis generally results in a self-limited illness characterized by fever, pharyngitis and lymphadenopathy. We present an exceptional case of an 18-year-old with infectious mononucleosis complicated by progressive bacterial superinfection and fulminant descending mediastinitis. After resuscitation, broad spectrum antibiotics, critical care support and definitive surgical management, they made a full recovery.

Overexpression of miR-214-3p in esophageal squamous cancer cells enhances sensitivity to cisplatin by targeting survivin directly and indirectly through CUG-BP1.

Based on its marked overexpression in multiple malignancies and its roles in promoting cell survival and proliferation, survivin is an attractive candidate for targeted therapy. Toward this end, a detailed understanding of the mechanisms regulating survivin expression in different cancer cells will be critical. We have previously shown that the RNA-binding protein (RBP) CUG-BP1 is overexpressed in esophageal cancer cells and post-transcriptionally regulates survivin in these cells. The objective of this study was to investigate the role of microRNAs (miRs) in regulating survivin expression in esophageal cancer cells. Using miR expression profiling analysis, we found that miR-214-3p is one of the most markedly downregulated miRs in two esophageal squamous cancer cell lines compared with esophageal epithelial cells. Interestingly, using miR target prediction programs, both survivin and CUG-BP1 mRNA were found to contain potential binding sites for miR-214-3p. Forced expression of miR-214-3p in esophageal cancer cells leads to a decrease in the mRNA and protein levels of both survivin and CUG-BP1. This effect is due to decreased mRNA stability of both targets. By contrast, silencing miR-214-3p in esophageal epithelial cells leads to an increase in both survivin and CUG-BP1 mRNA and protein. To determine whether the observed effect of miR-214-3p on survivin expression was direct, mediated through CUG-BP1, or both, binding studies utilizing biotin pull-down assays and heterologous luciferase reporter constructs were performed. These demonstrated that the mRNA of survivin and CUG-BP1 each contain two functional miR-214-3p-binding sites as confirmed by mutational analysis. Finally, forced expression of miR-214-3p enhances the sensitivity of esophageal cancer cells to cisplatin-induced apoptosis. This effect is abrogated with rescue expression of survivin or CUG-BP1. These findings suggest that miR-214-3p acts as a tumor suppressor and that its downregulation contributes to chemoresistance in esophageal cancer cells by targeting both survivin and CUG-BP1.

Roles of cellular polyamines in mucosal healing in the gastrointestinal tract.

The mammalian gastrointestinal (GI) mucosa is a rapidly self-renewing tissue in the body, and its integrity is preserved through the strict regulation of epithelial cell proliferation, growth arrest, and apoptosis. Polyamines are shown to play an important role in the regulation of gastrointestinal mucosal growth and healing after injury under physiological and various pathological conditions. In this review, we highlight the importance of cellular polyamines in the control GI mucosal proliferation, migration, apoptosis, angiogenesis and GI barrier function during mucosal repair after injury.

A simple, and potentially low-cost method for measuring the prevalence of childhood obesity.

BACKGROUND: Recent official publications have highlighted obesity as one of the biggest threats to public health and the prevalence of obesity in children is widely believed to be rising rapidly. However, there are no data on the prevalence of childhood obesity at a local level. We have developed a simple low-cost method of gaining such data by working with local schools. METHOD: We designed our method on the observation that numeracy and data handling skills are often taught in schools by getting children to measure their height and weight. We recruited seven schools and offered them a numeracy lesson plan suitable for year 5 (aged 9-10) children together with healthcare staff to attend the lesson. As part of the lesson, each child's height and weight was measured and recorded anonymously. Parental consent was obtained on an 'opt out' basis. The method was evaluated by questionnaire. RESULTS: We gained data on body mass index for 252 children. In total, 20% of the children were overweight, and 7% obese. The brief questionnaire survey indicated that both teachers and school nurses were happy with the method and would repeat it. Weighing was carried out sensitively. CONCLUSION: Our findings were in line with national studies of the prevalence of childhood obesity. The method was simple, low-cost and acceptable to schools and school nurses. There seems no reason why this project cannot be used more widely across the Primary Care Trust (PCT) and beyond. We now propose to roll out the method across all primary schools in Birmingham.

Effect of thyroid hormone on the development and gene expression of hormone receptors in rat testes in vivo.

Thyroid hormone is known to play a pivotal role in the regulation of prepuberal rat testes development and function with specific influence on the differentiation of Sertoli cells, the only cell type that expresses thyroid hormone receptors in testes. To explore in vivo effects of thyroid hormone on testes development and the regulation of testicular gene expression, the hyper- and hypothyroid rat models were established by T3 injection to pups (ip 100 microg/kg bw) and by oral administration of 6-N-propyl-2-thiouracil (PTU) to the lactating mother from days 1 to 21 post-delivery. Half of the rats from each group were sacrificed at 21 days of age, and the other half were allowed to recover with discontinued treatments from day 22 to day 50. At 21 days of age, a significantly elevated serum T3 level was observed in hyperthyroid rats (179.5 ng/dl) vs controls (97.5 ng/dl), and in hypothyroid rats a significantly lower level of T3 was detected (26.1 ng/dl). However, serum T4 concentration was significantly lower in both hyper- (0.105 microg/dl) and hypothyroid (0.058 microg/dl) rats compared to the controls (2.48 microg/dl). In recovered rats in which the serum T3 and T4 were restored to normal, the serum T levels remained remarkably lower in both hyper- and hypothyroid rats. The significantly decreased body and testes weights observed in both hyper- and hypothyroid rats at 21 days of age were not restored by the time they were 50 days old. Histological analyses of testes of 21-day-old hypothyroid rats revealed smaller-sized seminiferous tubules, incomplete lumen formation and delayed germ cell differentiation and in hyperthyroid rats an increased number of early stage spermatocytes was found. Testicular mRNA levels of follicle-stimulating hormone receptor (FSH-R), luteinizing hormone receptor (LH-R) and androgen binding protein (ABP) were studied by Northern blot hybridization. At 21 days of age data showed that FSH-R mRNA levels were significantly higher in both hyper- and hypothyroid rat testes compared to controls, but no differences were detected in recovered 50-day-old rats. Significantly decreased ABP mRNA levels were detected only in hypothyroid rat testes compared to those in both the hyperthyroid and control groups at 21 days of age, but no significant change was observed in recovered 50-day-old rats. To further evaluate the effect of thyroid hormone on the Leydig cell function, the 2.3/2.6 kb specific LH-R hybridization bands were detected with rat LH-R cRNA probe. Significant suppression of LH-R mRNA levels was only observed in the hypothyroid rat testes at 50 days of age. The testicular thyroid hormone receptors (TRs) and the regulation of TR by thyroid hormone were investigated using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) assays. Both TRalpha and TRbeta mRNAs were identified in the testes from 21- and/or 50-day-old rats. TRalpha mRNA levels were significantly increased in hypothyroid rat testes and were suppressed in hyperthyroid rats at 21 days of age and no changes of TRalpha mRNA were found in recovered animals. Our in vivo data strongly suggest that the thyroid hormone directly affects the development of prepuberal testes and the regulation of FSH-R and ABP gene expression in Sertoli cells, as well as the LH-R mRNA levels in Leydig cells, which may lead to further modulating the effect of gonadotropins on testes function.

Polyamine depletion stabilizes p53 resulting in inhibition of normal intestinal epithelial cell proliferation.

The p53 nuclear phosphoprotein plays a critical role in transcriptional regulation of target genes involved in growth arrest and apoptosis. The natural polyamines, including spermidine, spermine, and their precursor putrescine, are required for cell proliferation, and decreasing cellular polyamines inhibits growth of the small intestinal mucosa. In the current study, we investigated the mechanisms of regulation of p53 gene expression by cellular polyamines and further determined the role of the gene product in the process of growth inhibition after polyamine depletion. Studies were conducted both in vivo and in vitro using rats and the IEC-6 cell line, derived from rat small intestinal crypt cells. Levels for p53 mRNA and protein, transcription and posttranscription of the p53 gene, and cell growth were examined. Depletion of cellular polyamines by treatment with alpha-difluoromethylornithine (DFMO) increased p53 gene expression and caused growth inhibition in the intact small intestinal mucosa and the cultured cells. Polyamine depletion dramatically increased the stability of p53 mRNA as measured by the mRNA half-life but had no effect on p53 gene transcription in IEC-6 cells. Induction of p53 mRNA levels in DFMO-treated cells was paralleled by an increase in the rate of newly synthesized p53 protein. The stability of p53 protein was also increased after polyamine depletion, which was associated with a decrease in Mdm2 expression. When polyamine-deficient cells were exposed to exogenous spermidine, a decrease in p53 gene expression preceded an increase in cellular DNA synthesis. Inhibition of the p53 gene expression by using p53 antisense oligodeoxyribonucleotides significantly promoted cell growth in the presence of DFMO. These findings indicate that polyamines downregulate p53 gene expression posttranscriptionally and that growth inhibition of small intestinal mucosa after polyamine depletion is mediated, at least partially, through the activation of p53 gene.

NF-kappaB activation and susceptibility to apoptosis after polyamine depletion in intestinal epithelial cells.

The maintenance of intestinal mucosal integrity depends on a balance between cell renewal and cell death, including apoptosis. The natural polyamines, putrescine, spermidine, and spermine, are essential for mucosal growth, and decreasing polyamine levels cause G(1) phase growth arrest in intestinal epithelial (IEC-6) cells. The present study was done to determine changes in susceptibility of IEC-6 cells to apoptosis after depletion of cellular polyamines and to further elucidate the role of nuclear factor-kappaB (NF-kappaB) in this process. Although depletion of polyamines by alpha-difluoromethylornithine (DFMO) did not directly induce apoptosis, the susceptibility of polyamine-deficient cells to staurosporine (STS)-induced apoptosis increased significantly as measured by changes in morphological features and internucleosomal DNA fragmentation. In contrast, polyamine depletion by DFMO promoted resistance to apoptotic cell death induced by the combination of tumor necrosis factor-alpha (TNF-alpha) and cycloheximide. Depletion of cellular polyamines also increased the basal level of NF-kappaB proteins, induced NF-kappaB nuclear translocation, and activated the sequence-specific DNA binding activity. Inhibition of NF-kappaB binding activity by sulfasalazine or MG-132 not only prevented the increased susceptibility to STS-induced apoptosis but also blocked the resistance to cell death induced by TNF-alpha in combination with cycloheximide in polyamine-deficient cells. These results indicate that 1) polyamine depletion sensitizes intestinal epithelial cells to STS-induced apoptosis but promotes the resistance to TNF-alpha-induced cell death, 2) polyamine depletion induces NF-kappaB activation, and 3) disruption of NF-kappaB function is associated with altered susceptibility to apoptosis induced by STS or TNF-alpha. These findings suggest that increased NF-kappaB activity after polyamine depletion has a proapoptotic or antiapoptotic effect on intestinal epithelial cells determined by the nature of the death stimulus.

Ca2+-RhoA signaling pathway required for polyamine-dependent intestinal epithelial cell migration.

Expression of voltage-gated K(+) (Kv) channel genes is regulated by polyamines in intestinal epithelial cells (IEC-6 line), and Kv channel activity is involved in the regulation of cell migration during early restitution by controlling membrane potential (E(m)) and cytosolic free Ca2+ concentration ([Ca2+](cyt)). This study tests the hypothesis that RhoA of small GTPases is a downstream target of elevated ([Ca2+](cyt)) following activation of K(+) channels by increased polyamines in IEC-6 cells. Depletion of cellular polyamines by alpha-difluoromethylornithine (DFMO) reduced whole cell K+ currents [I(K(v))] through Kv channels and caused membrane depolarization, which was associated with decreases in ([Ca2+](cyt)), RhoA protein, and cell migration. Exogenous polyamine spermidine reversed the effects of DFMO on I(K(v)), E(m), ([Ca2+](cyt)), and RhoA protein and restored cell migration to normal. Elevation of ([Ca2+](cyt)) induced by the Ca2+ ionophore ionomycin increased RhoA protein synthesis and stimulated cell migration, while removal of extracellular Ca2+ decreased RhoA protein synthesis, reduced protein stability, and inhibited cell motility. Decreased RhoA activity due to Clostridium botulinum exoenzyme C(3) transferase inhibited formation of myosin II stress fibers and prevented restoration of cell migration by exogenous spermidine in polyamine-deficient cells. These findings suggest that polyamine-dependent cell migration is partially initiated by the formation of myosin II stress fibers as a result of Ca2+-activated RhoA activity.

Compensating for provider nonresponse using response propensities to form adjustment cells: the National Immunization Survey.

OBJECTIVES: The National Immunization Survey (NIS) uses two phases of data collection to obtain vaccination information from a sample of young children: a random-digit-dialing (RDD) survey for identifying households with children 19-35 months of age, followed by a mail survey for obtaining provider-reported vaccination histories about these children. Provider-reported vaccination histories are used to estimate vaccination coverage rates. In 1998, provider-reported vaccination histories were not obtained for 32.9% of children with a completed RDD interview. This report describes the statistical methods adopted in 1998 to reduce the bias in vaccination coverage estimates that could result from "vaccination history nonresponse," that is, differences between children for whom provider data was obtained and those for whom it was not obtained. METHODS: In the methods adopted in 1998, children with completed NIS RDD interviews are grouped into adjustment cells defined by their propensity to have adequate provider data. Sampling weights of children with adequate provider data are divided by the cell-specific weighted response rate to allow these children to represent all children in the cell. RESULTS: Using an "optimal" number of cells, the overall extent of bias reduction was 0.5%, suggesting that provider nonresponse bias was small. Authoritative literature suggests using five cells. No statistically significant differences were observed in vaccination coverage estimates when comparing estimates based on the "optimal" number of cells with five cells. Thus, five adjustment cells are used to reduce provider nonresponse bias in the NIS vaccination coverage estimates. No substantively important differences were observed between estimates based on the methodology used prior to 1998 and the methodology adopted in 1998.

Orthotopic heart transplantation with concurrent aortic valve replacement and coronary artery bypass grafting.

We report a case of successful orthotopic heart transplantation of a donor heart with normal ventricular function, 2-vessel coronary artery disease, and a bicuspid aortic valve, which required concurrent aortic valve replacement and coronary artery bypass grafting. In confronting the disparities in demand and supply, we must consider the so-called marginally acceptable heart for either critically ill recipients or those who may be disadvantaged on the waiting list.

Expression of the TGF-beta receptor gene and sensitivity to growth inhibition following polyamine depletion.

Our previous studies have shown that inhibition of polyamine biosynthesis increases the sensitivity of intestinal epithelial cells to growth inhibition induced by exogenous transforming growth factor-beta (TGF-beta). This study went further to determine whether expression of the TGF-beta receptor genes is involved in this process. Studies were conducted in the IEC-6 cell line, derived from rat small intestinal crypt cells. Administration of alpha-difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase (the rate-limiting enzyme for polyamine synthesis), for 4 and 6 days depleted cellular polyamines putrescine, spermidine, and spermine in IEC-6 cells. Polyamine depletion by DFMO increased levels of the TGF-beta type I receptor (TGF-betaRI) mRNA and protein but had no effect on the TGF-beta type II receptor expression. The induced TGF-betaRI expression after polyamine depletion was associated with an increased sensitivity to growth inhibition induced by exogenous TGF-beta but not by somatostatin. Extracellular matrix laminin inhibited IEC-6 cell growth without affecting the TGF-beta receptor expression. Laminin consistently failed to induce the sensitivity of TGF-beta-mediated growth inhibition. In addition, decreasing TGF-betaRI expression by treatment with retinoic acid not only decreased TGF-beta-mediated growth inhibition in normal cells but also prevented the increased sensitivity to exogenous TGF-beta in polyamine-deficient cells. These results indicate that 1) depletion of cellular polyamines by DFMO increases expression of the TGF-betaRI gene and 2) increased TGF-betaRI expression plays an important role in the process through which polyamine depletion sensitizes intestinal epithelial cells to growth inhibition induced by TGF-beta.

The effects of heparin and extracorporeal circulation on platelet counts and platelet microaggregation during cardiopulmonary bypass.

BACKGROUND: Cardiopulmonary bypass is associated with platelet activation and reduced platelet counts. Platelet activation may artifactually lower platelet counts by causing aggregation. In vivo platelet activation may increase existent platelet microaggregation ex vivo. We studied platelet counts and existent platelet microaggregation at different stages of cardiopulmonary bypass. METHODS: Twenty-one patients were studied before and after heparinization (300 U. kg(-1)) and at the end of cardiopulmonary bypass. Unaggregated (or single) platelets were counted in hirudin-anticoagulated blood, and total platelets were counted in ethylenediaminetetraacetic acid-anticoagulated blood. RESULTS: The total platelet count, 198 +/- 61 x 10(9). L(-1), was unaffected by heparin and stayed at 197 +/- 60 x 10(9). L(-1) (P =.7) but fell during extracorporeal circulation; the hemodilution-corrected count was 163 +/- 52 x 10(9). L(-1) (P =.0004). Heparinization reduced the unaggregated platelet count from (mean +/- 1 SD) 178 +/- 62 x 10(9). L(-1) to 155 +/- 60 x 10(9). L(-1) (P =.0001). Extracorporeal circulation had little additional effect. The hemodilution-corrected count was 142 +/- 48 x 10(9). L(-1) (P =.6). CONCLUSIONS: Heparinization caused platelet activation and increased existent platelet microaggregation ex vivo. During extracorporeal circulation, there was a reduction in total platelets that was greater than could be explained by hemodilution alone, but the unaggregated platelet count did not change significantly when corrected for hemodilution. Furthermore, the increased platelet microaggregation observed after heparinization was no longer evident after this loss. These findings suggest that during extracorporeal circulation, the platelets that formed into microaggregates after heparinization were lost from the circulation in preference to single platelets.