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.

Effects of tachykinins on the secretory activity of rat Sertoli cells in vitro.

In the present study we investigated the effects of various tachykinins on the secretory activity of rat Sertoli cells in vitro. Sertoli cells were isolated from testes of immature Sprague Dawley rats, cultured for 4 days and thereafter incubated with three concentrations (0.1 pM, 1 pM or 100 pM) of substance P (SP), neurokinin A (NKA), neuropeptide K (NPK) or neuropeptide gamma (NPG) for 24 h. Levels of transferrin and lactic acid were determined in the culture media and expressed per micrograms of cellular DNA. Among all the peptides studied, NPG exhibited the greatest stimulatory effect on the release of transferrin and lactate, with NKA and NPK being less potent and SP being the least potent. Also, the effects of tachykinins on the aromatase activity of cultured Sertoli cells, as reflected by their ability to metabolize testosterone to estradiol (E2), were studied. No stimulatory effect was observed at lower concentrations (1 pM), while at 100 pM both NPG and NKA increased estradiol levels in the medium. SP and NPK had no significant effect on estradiol levels in the medium. This study reveals that tachykinins are able to influence the secretory activity of Sertoli cells, and that some of these peptides can also enhance the aromatase activity. Thus there is a possibility that tachykinins may have a physiological role as modulators of the function of Sertoli cells.

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.

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.

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.

Effects of photoperiod on hypothalamic and anterior pituitary tachykinins of male Siberian hamsters during development.

In previous reports from our laboratory we showed that the hypothalamus and especially the anterior pituitary gland of the Siberian hamster contain very high concentrations of substance P- and neurokinin A-like immunoreactive substances, as compared with other common laboratory rodents. It was thought, therefore, that a study of the developmental changes of these two tachykinins in the hypothalamus and anterior pituitary of male Siberian hamsters would be of interest. In addition, as this species is very sensitive to changes in environmental light, these studies were carried out in animals kept under short or long daily photoperiods. The results of this investigation show that in male Siberian hamsters, photoperiod did not markedly influence the hypothalamic concentrations of substance P- and neurokinin A-like immunoreactive substances, which steadily increased from prepuberty up to 40-50 days of age. The influence of photoperiod, however, was much more marked on tachykinin levels in the anterior pituitary gland, because the developmental increase of tachykinins in this gland was significantly more evident in animals kept under short daily photoperiods than in animals under long daily exposure to light. These results are similar to those previously obtained in female Siberian hamsters, in spite of the fact that estradiol and testosterone seem to have opposite effects on anterior pituitary tachykinin concentrations. It seems, therefore, that, in addition to gonadal steroids, other factors may be important mediators of the tachykinin response to photoperiods in the anterior pituitary of the male Siberian hamster.

Developmental changes of tachykinins in the hypothalamus and anterior pituitary of female Siberian hamsters from prepuberty to adulthood.

The developmental changes of hypothalamic and anterior pituitary tachykinin concentrations were studied in female Siberian hamsters kept either under short (SD) or long (LD) daily photoperiods. The animals were killed between 15 and 70 days of age. Hypothalamic NKA sharply increased starting at 15 days up to 50 days in LD animals, and between 20 and 60 days in SD animals. Hypothalamic SP levels increased in a similar manner in SD animals, but in LD animals the increment was less pronounced, with increased levels from day 20 to 40, followed by a plateau. In the anterior pituitary gland, NKA concentrations in LD animals increased at 40 days of age, with only slight increases afterward, but overall the increment curve was considerably flatter than for hypothalamic NKA. In SD animals, the increase of anterior pituitary NKA was much steeper than in LD animals. However, the total content of NKA in the AP was similar in both SD and LD animals, because the AP weight was considerably higher in LD- than in SD-exposed hamsters. These results showed that photoperiod did not markedly affect the developmental changes in hypothalamic NKA. The developmental changes in anterior pituitary NKA concentrations were considerably smaller than in the hypothalamus in LD animals, but in SD animals they were much steeper. NKA concentrations in the anterior pituitary were markedly affected by the photoperiod. Concentrations of NKA in the anterior pituitary of the Siberian hamster at the age of 15 days of age were already higher than in the anterior pituitary of adult rats or Syrian hamsters.(ABSTRACT TRUNCATED AT 250 WORDS)

The detection of thyrotropin-releasing hormone (TRH) and TRH receptor gene expression in Siberian hamster testes.

Thyrotropin-releasing hormone (TRH) from the hypothalamus is the major regulator of TSH synthesis and secretion. Most recently, TRH and TRH receptors (TRH-R), as well as their mRNAs, have been identified in rat testis. To expand our knowledge on the testicular TRH and TRH receptor gene expression in different species, in the present study the mRNA levels of testicular TRH and TRH-R were investigated in Siberian hamsters. To further localize the cellular sites of the gene expression, the animal model was treated with a single injection of ethylene dimethane sulfonate (EDS) (i.p., 80 mg/kg body weight), a compound known as to specifically eliminate testicular Leydig cells. The elimination of Leydig cells induced by EDS treatment was confirmed by histological studies of the testis sections and by serum hormonal analyses, which showed a dramatic reduction of serum testosterone (T) levels and significantly elevated serum LH concentrations. Messenger RNA levels of TRH and TRH-R in the testes were determined by Northern blot analyses quantitated with densitometry scanning. The results showed that specific TRH-R mRNA, 3.8 kb in size, was identified in Siberian hamster testes and the mRNA levels were significantly elevated in the EDS-treated testes compared to the controls (p < 0.01). Testicular TRH mRNA was also detected; however, no significant differences in TRH mRNA levels were found between EDS-treated and control groups. The size of TRH mRNA was characterized as about 1.2 kb in hamster testes, which was smaller than that observed in the rat hypothalamus (1.6 kb) and in the rat testis (2.0 kb). Further studies by RNase H digestion revealed the presence of smaller TRH transcripts in the hamster testes than those in the rat testis. No hybridization signal for TRH mRNA was detected by RNase protection assay, when a rat TRH riboprobe was applied to hamster testis RNA, suggesting the limited homology of TRH gene sequences between these two species. Our results demonstrate that both TRH and TRH-R genes are expressed in Siberian hamster testes, and a significant increase of TRH-R mRNA levels occurs in the Leydig cell eliminated hamster testes. Unlike the rat testicular TRH mRNA mainly detected in Leydig cells, in hamster TRH mRNA could also be detected in other testicular compartment.

Effects of photoperiod on testicular inhibin-alpha and androgen binding protein mRNA expression during postnatal development in Siberian hamsters, Phodopus sungorus.

The effects of short photoperiod (SPP) on testicular inhibin-alpha and androgen binding protein (ABP) mRNA expression were investigated in Siberian hamsters during postnatal development. Hamsters were raised in either long photoperiod (LPP; 16L:8D) or in a SPP (6L:18D). Hamsters were sacrificed at the following developmental ages: preweaning (18-20 days), immature (28-30 days), pubertal (38-40 days), postpubertal (48-50 days) and adult (60-62 days; n = 7-12 animals per group). Body and testicular weights were determined and plasma FSH levels were measured by validated RIA. As expected, testicular weight and circulating FSH levels were significantly lower in hamsters raised in SPP than in LPP animals. Photoperiod had no significant effect on body weight except during postpubertal age. The northern analyses of inhibin-alpha and ABP expression in the testes revealed that the corresponding relative mRNA levels were higher in animals exposed to SPP than in animals from LPP. These findings suggest that the testes of hamsters exposed to a SPP can synthesize inhibin-alpha and ABP, and we speculate that the release of these proteins may be regulated by photoperiod and the role of FSH in the control of inhibin-alpha and ABP gene expression in male Siberian hamsters may be minimal.

Variance estimation for complex surveys using replication techniques.

The analysis of survey data requires the application of special methods to deal appropriately with the effects of the sample design on the properties of estimators and test statistics. The class of replication techniques represents one approach to handling this problem. This paper discusses the use of these techniques for estimating sampling variances, and the use of such variance estimates in drawing inferences from survey data. The techniques of the jackknife, balanced repeated replication (balanced half-samples), and the bootstrap are described, and the properties of these methods are summarized. Several examples from the literature of the use of replication in analysing large complex surveys are outlined.

Do Asians with diabetes in Sandwell receive inferior primary care? A retrospective cohort study.

Although diabetes is more prevalent among Asian people, Asians with diabetes are anecdotally believed to receive a lesser standard of care, compared with non-Asians. The aim of this study was to evaluate whether Asian patients with diabetes in Sandwell receive an inferior standard of care in primary care compared with non-Asians. Standards were based on tests carried out, in compliance with Sandwell's Diabetes Local Clinical Guideline. Data were collected from records of 774 patients with diabetes in 14 Sandwell practices. Proportions were recorded of Asian patients receiving specified tests, compared with non-Asians. No significant differences were observed between Asians and non-Asians for checks on feet, eyes, body mass index (BMI), smoking or blood pressure. Significantly fewer Asians received an HbA1c check. The mean HbA1c value was higher in Asians. More Asian patients received a urine test than non-Asians. Asian patients generally had lower BMI values. When stratified by practice however, no significant differences between Asians and non-Asians were observed for any single check. No significant differences were found between the overall proportions of checks carried out between Asians and non-Asians. A wide variation was observed in the proportion of patients who had individual checks done, between practices. There were no systematic differences in the standard of care given to Asian and non-Asian patients. Practices varied a great deal in the extent to which they carry out, and record, checks on patients with diabetes. A possible explanation for the reason that no summary result showed a significant difference was due to the confounding effect of the practice: that general practices tended to treat all their patients--Asian and non-Asian--similarly. Nevertheless, general practitioners should therefore take steps to ensure that all patients with diabetes have these checks at recommended intervals.

Effect of prolactin on accessory sex organs of prepuberal male albino rats: an in vitro study.

The in vitro studies on the effect of hypophysial gonadotropins (PRL, FSH, LH) on the maturation events of accessory sex organs in prepuberal male rats revealed that prolactin (PRL) alone has both direct as well as androgen mediated effect on the maturation activities. The effect of PRL is age dependent and it had higher activation on the gland system than the duct system.

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.