TYPE TESTING OF LiF:Mg,Cu,P (TLD-100H) WHOLE-BODY DOSEMETERS FOR THE ASSESSMENT OF Hp(10) AND Hp(0.07)

In this work, the initial results of the type testing of the LiF:Mg,Cu,P (TLD-100H) whole-body personal dosemeters are presented. An assessment of reproducibility, linearity of the response, the residual signal as a function of the dose, energy and angular dependence of the response was performed. In general, the dosemeters show good reproducibility for different dose values and a linear behaviour for a range between 0.1 and 300 mSv. The detection limits obtained are lower than 50 μSv. The system presents a good energy and angular response for different radiation qualities.

Validación del instrumento: Competencias del personal de enfermería en Salud Pública, en el contexto mexicano

Introducción: Cuando se utilicen cuestionarios desarrollados en otros países e idiomas en estudios científicos, además de traducirlos, es necesario su adaptación cultural y validación, el objetivo de esta investigación es contar con un instrumento válido y confiable para evaluar las competencias del personal de enfermería en salud pública, para aplicarlo en el contexto mexicano. Metodología: El estudio fue de tipo descriptivo-transversal, multietápico, la población se integró en 3 grupos para las 3 diferentes etapas, en la primera, por un grupo de 10 expertos en investigación de la Facultad de Enfermería de Tampico, de la Universidad Autónoma de Tamaulipas, México y 17 profesionales que laboran en el primer nivel de atención; en la segunda, 30 profesionales de enfermería y en la tercera 177 profesionales que trabajan en el campo de la salud pública, todos ellos de tres jurisdicciones del Sur de Tamaulipas, México, el muestreo fue por conveniencia. Resultados: En cuanto a los tres procesos que se realizaron para la validación del instrumento, se mostraron resultados adecuados y satisfactorios para su aplicación, ya que en la prueba de V-Aiken se obtuvo un resultado cercano a 1, en el proceso semántico sólo se realizó modificación a una palabra; a través de la prueba piloto se obtuvo un resultado de 0.97 en el alfa de cronbach. Conclusiones: El instrumento se considera válido para iniciar con la evaluación de las mencionadas competencias, para contar con un diagnóstico inicial de las áreas de oportunidad para personal de enfermería.

Reproductive aspects of the Atlantic angel shark Squatina dumeril in the southern Caribbean Sea

The maturity and reproduction of the Atlantic angel shark Squatina dumeril were assessed using 77 females (29·2-110·4 cm total length; L_T ) and 269 males (58·7-108·2 cm L_T ) harvested by artisanal gillnetters off Venezuela. The biased sex ratio implied segregation or sex-specific gear selectivity. Based on the development of the reproductive tract, 50% L_T at sexual maturity (L_T50 , mean ± s.e.) for females and males were estimated at 86·14 ± 0·64 and 81·55 ± 0·12 cm, respectively. Uterine fecundity ranged between one and six and with a maximum embryo size of 25·7 cm L_T . Gravid females were observed from August to December, including those close to parturition and while the gestation period was not confirmed, the size of ovarian follicles among some specimens implied protraction. The low fecundity of the species supports close monitoring of catches.

ENVIRONMENTAL MONITORING WITH PASSIVE DETECTORS AT CTN IN PORTUGAL

The aim of this work is to present the methods in use for environmental dose assessment with passive detectors at Campus Tecnológico e Nuclear (CTN) of Instituto Superior Técnico, in Portugal. The methods are based on LiF:Mg,Ti (TLD-100) detectors inserted in Harshaw holders placed at four locations and exchanged on a quarterly basis. An initial group of measurements allowed the estimation of the time interval necessary to attain a stable value, the determination of a fading factor, as well as the calculation method for the assessment of the ambient dose equivalent rate.

FADING EFFECT OF LiF:Mg,Ti AND LiF:Mg,Cu,P Ext-Rad AND WHOLE-BODY DETECTORS

Thermoluminescence dosemeters are widely used in individual and environmental monitoring. The aim of this work was to compare the thermal stability of dosemeters of the Ext-Rad and whole-body card types with LiF:Mg,Ti and LiF:Mg,Cu,P detectors stored at different temperatures and periods. The dosemeters were stored at 0°C, room temperature and 40°C for periods that lasted 8, 30, 45, 90 and 120 d. In general, TLD-100H detectors present higher TL signal stability than TLD-100 detectors. The intensity of the signal remained constant for both materials for storage periods at 0°C. At RT the same results was observed for TLD-100H. For TLD-100 detectors, a maximum variation of 22 % was registered for the longest period. At 40°C the TL signal decreased with storage time for both detectors. The TL signal of TLD-100H detectors presented maximum variations of 12 % whereas for TLD-100 detectors, larger variations of 25 % were observed.

Long-term stability of a TLD-based individual monitoring system

The thermoluminescence dosemeter (TLD) system at the Individual Monitoring Service (IMS) of the Nuclear Technology Institute (ITN) at the Radiological Protection and Nuclear Safety Department (DPRSN) comprises two 6600 Harshaw readers and the Harshaw 8814 TL card and the holder containing two LiF:Mg,Ti (TLD-100) dosemeters for the evaluation of H(p)(10) and H(p)(0.07). The readers are calibrated on a monthly basis and as part of the quality assurance programme implemented at the IMS a set of dosemeters is issued monthly to the DPRSN's Standard Dosimetry Laboratory for linearity measurements. The results obtained since November 2001 are presented. Fading and sensitivity change experiments are carried out every month covering 8 week periods so that enough time is given to simulate issuing, integrating and receiving times and respective delays. A set of 96 dosemeters organised in eight subsets of 12 are used. In each subset, four dosemeters are irradiated and stored at room temperature (RT), four are not irradiated at all and the last four are irradiated after storage. The 12 dosemeters of each subset are readout at the same time, one per week, covering the 8 week period. The results from the sets irradiated and stored at different periods allowed for the evaluation of fading and sensitivity changes experienced over the whole monitoring period and respective preparation time and readout delays. Time evolution charts of the reader calibration factors, of the linearity parameters and of the evolution of the integrated area in the region of dosimetric interest with storage at RT were obtained. This paper aims to quantify the long-term stability of the TLD system in use at the IMS.

Implications of the high voltage induced variation on TL readings

The high voltage (HV) induced variation on the thermoluminescence (TL) and on the reference light (RL) intensity was investigated in a previous work, which also allowed for the definition of warning levels for all the parameters of the readers' start up test. Based on the results obtained, a modification of the start up procedure was suggested: 'a 10 min warm up time was allowed prior to the beginning of the reader's start up tests. The actual and previous HV values should differ less than +/-5 V. In case it exceeds, a second test should be performed. If the difference exceeds +/-10 V, the voltage should be manually adjusted to the previous value and a calibration of the reader is needed. Should this occur for more than two successive days, maintenance should be called'. The results of the readers' start up tests obtained since the implementation of the start up procedure are analysed and the warning levels considered are discussed. Charts of the HV-induced variation on the TL and RL readings were obtained, compared with the preliminary results and the implications on the start up procedure are discussed.

Mapping Ds insertions in barley using a sequence-based approach

A transposon tagging system, based upon maize Ac/Ds elements, was developed in barley (Hordeum vulgaresubsp. vulgare). The long-term objective of this project is to identify a set of lines with Ds insertions dispersed throughout the genome as a comprehensive tool for gene discovery and reverse genetics. AcTPase and Ds-bar elements were introduced into immature embryos of Golden Promise by biolistic transformation. Subsequent transposition and segregation of Ds away from AcTPase and the original site of integration resulted in new lines, each containing a stabilized Ds element in a new location. The sequence of the genomic DNA flanking the Ds elements was obtained by inverse PCR and TAIL-PCR. Using a sequence-based mapping strategy, we determined the genome locations of the Ds insertions in 19 independent lines using primarily restriction digest-based assays of PCR-amplified single nucleotide polymorphisms and PCR-based assays of insertions or deletions. The principal strategy was to identify and map sequence polymorphisms in the regions corresponding to the flanking DNA using the Oregon Wolfe Barley mapping population. The mapping results obtained by the sequence-based approach were confirmed by RFLP analyses in four of the lines. In addition, cloned DNA sequences corresponding to the flanking DNA were used to assign map locations to Morex-derived genomic BAC library inserts, thus integrating genetic and physical maps of barley. BLAST search results indicate that the majority of the transposed Ds elements are found within predicted or known coding sequences. Transposon tagging in barley using Ac/Ds thus promises to provide a useful tool for studies on the functional genomics of the Triticeae.

Engineered Resistance Against Papaya ringspot virus in Venezuelan Transgenic Papayas

Local varieties of papaya grown in the Andean foothills of Mérida, Venezuela, were transformed independently with the coat protein (CP) gene from two different geographical Papaya ringspot virus (PRSV) isolates, designated VE and LA, via Agrobacterium tumefaciens. The CP genes of both PRSV isolates show 92 and 96% nucleotide and amino acid sequence similarity, respectively. Four PRSV-resistant R0 plants were intercrossed or selfed, and the progenies were tested for resistance against the homologous isolates VE and LA, and the heterologous isolates HA (Hawaii) and TH (Thailand) in greenhouse conditions. Resistance was affected by sequence similarity between the transgenes and the challenge viruses: resistance values were higher for plants challenged with the homologous isolates (92 to 100% similarity) than with the Hawaiian (94% similarity) and, lastly, Thailand isolates (88 to 89% similarity). Our results show that PRSV CP gene effectively protects local varieties of papaya against homologous and heterologous isolates of PRSV.

The role of prospective randomized clinical trials in pediatric surgery: state of the art?

PURPOSE

This study sought to determine the role of randomized controlled trials (RCT) in the evolution of pediatric surgical practice.

METHODS

The authors used a computer-assisted literature search to identify all clinical trials related to pediatric surgery published in the English-language literature from 1966 through 1999. Each article was reviewed in detail for purpose, content, conduct, and quality of the trial. The authors assessed quality with a previously validated instrument (Chalmers Qualitative Assessment).

RESULTS

The authors identified 134 RCTs related to pediatric surgery over the past 33 years. This accounts for 0.17% of 80,377 articles published in the field. The areas of surgery studied were analgesia 65 (49%), antibiotics 17 (13%), extracorporeal membrane oxygenation (ECMO) 9 (7%), gastrointestinal, burns, oncology, minimally invasive surgery, vascular access, congenital anomalies, and trauma (each <5%). Only 16 (12%) trials compared 2 surgical therapies, 9 (7%) compared a medical versus a surgical therapy, and 109 (81%) compared 2 medical therapies in surgical patients. Fourteen (10%) RCTs were funded by peer-reviewed agencies. Only 17 (13%) RCTs included a biostatistician as an author or a consultant. Trial design included calculation of sample size and statistical power in 21 (16%) RCTs. Method of randomization was reported in only 51 (38%). The test statistic and observed probability value was reported in 15 (11%).

CONCLUSIONS

Clinical trials are used infrequently to answer questions related to pediatric surgery. When RCTs are utilized, they often suffer from poor trial design, inadequate statistical analysis, and incomplete reporting. Pediatric surgery could benefit from increased expertise, funding, and participation in clinical trials.

Transposon-mediated single-copy gene delivery leads to increased transgene expression stability in barley

Instability of transgene expression in plants is often associated with complex multicopy patterns of transgene integration at the same locus, as well as position effects due to random integration. Based on maize transposable elements Activator (Ac) and Dissociation (Ds), we developed a method to generate large numbers of transgenic barley (Hordeum vulgare var Golden Promise) plants, each carrying a single transgene copy at different locations. Plants expressing Ac transposase (AcTPase) were crossed with plants containing one or more copies of bar, a selectable herbicide (Basta) resistance gene, located between inverted-repeat Ds ends (Ds-bar). F(1) plants were self-pollinated and the F(2) generation was analyzed to identify plants segregating for transposed Ds-bar elements. Of Ds-bar transpositions, 25% were in unlinked sites that segregated from vector sequences, other Ds-bar copies, and the AcTPase gene, resulting in numerous single-copy Ds-bar plants carrying the transgene at different locations. Transgene expression in F(2) plants with transposed Ds-bar was 100% stable, whereas only 23% of F(2) plants carrying Ds-bar at the original site expressed the transgene product stably. In F(3) and F(4) populations, transgene expression in 81.5% of plants from progeny of F(2) plants with single-copy, transposed Ds-bar remained completely stable. Analysis of the integration site in single-copy plants showed that transposed Ds-bar inserted into single- or low-copy regions of the genome, whereas silenced Ds-bar elements at their original location were inserted into redundant or highly repetitive genomic regions. Methylation of the non-transposed transgene and its promoter, as well as a higher condensation of the chromatin around the original integration site, was associated with plants exhibiting transgene silencing.

Volatile aldehydes are promising broad-spectrum postharvest insecticides

A variety of naturally occurring aldehydes common in plants have been evaluated for their insecticidal activity and for phytotoxicity to postharvest fruits, vegetables, and grains. Twenty-nine compounds were initially screened for their activity against aphids on fava bean leaf disks. Application under reduced pressure (partial vacuum) for the first quarter of fumigation increased insecticidal activity severalfold. The 11 best aldehydes were assayed against aphids placed under the third leaf of whole heads of iceberg lettuce using the same two-tier reduced-pressure regime, which caused no additional detriment to the commodity over fumigation at atmospheric pressure. Phytotoxicity to naked and wrapped iceburg lettuce, green and red table grapes, lemon, grapefruit, orange, broccoli, avocado, cabbage, pinto bean, and rice at doses that killed 100% of aphids was recorded for three promising fumigants: propanal, (E)-2-pentenal, and 2-methyl-(E)-2-butenal. These three compounds have excellent potential as affordable postharvest insect control agents, killing 100% of the aphids with little or no detectable harm to a majority of the commodities tested. Preliminary assays indicate that similar doses are also effective against mealybugs, thrips, and whitefly.

Volatile aldehydes are promising broad-spectrum postharvest insecticides

A variety of naturally occurring aldehydes common in plants have been evaluated for their insecticidal activity and for phytotoxicity to postharvest fruits, vegetables, and grains. Twenty-nine compounds were initially screened for their activity against aphids on fava bean leaf disks. Application under reduced pressure (partial vacuum) for the first quarter of fumigation increased insecticidal activity severalfold. The 11 best aldehydes were assayed against aphids placed under the third leaf of whole heads of iceberg lettuce using the same two-tier reduced-pressure regime, which caused no additional detriment to the commodity over fumigation at atmospheric pressure. Phytotoxicity to naked and wrapped iceburg lettuce, green and red table grapes, lemon, grapefruit, orange, broccoli, avocado, cabbage, pinto bean, and rice at doses that killed 100% of aphids was recorded for three promising fumigants: propanal, (E)-2-pentenal, and 2-methyl-(E)-2-butenal. These three compounds have excellent potential as affordable postharvest insect control agents, killing 100% of the aphids with little or no detectable harm to a majority of the commodities tested. Preliminary assays indicate that similar doses are also effective against mealybugs, thrips, and whitefly.

Laparoscopic repair of paraesophageal hiatal hernias

BACKGROUND

Regardless of symptoms, paraesophageal hiatal hernias should be repaired in order to prevent complications. This study reports the University of California San Francisco experience with laparoscopic repair of paraesophageal hiatal hernias, emphasizing the technical steps essential for good results.

PATIENTS AND METHODS

From May 1993 to September 1997, 55 patients, 27 women and 28 men, with a mean age of 67 years (range, 35-102 years) underwent laparoscopic repair of paraesophageal hernias at the University of California San Francisco. Symptoms, which had been present an average of 85 months before surgery, consisted mainly of pain (55%), heartburn (52%), dysphagia (45%), and regurgitation (41%). Of the four patients who presented with acute illness, two had gastric obstruction, one had severe dyspnea, and one had gastric bleeding. Endoscopy demonstrated esophagitis in 25 (69%) of 36 patients, and 24-hour pH-monitoring demonstrated acid reflux in 22 (67%) of 33 patients. Manometry detected severely impaired distal esophageal peristalsis in 17 (52%) of 33 patients. The preferred operation consisted of reduction of the hernia, excision of the sack and the gastric fat pad, closure of the enlarged hiatus without mesh, and construction of a fundoplication anchored by sutures within the abdomen.

RESULTS

Of the 55 patients, the operations of 49 were completed laparoscopically using the following reconstructions: Guarner (270-degree) fundoplication (30 patients); Nissen fundoplication (10 patients); and gastropexy (9 patients). Five (9%) operations were converted to laparotomies. The average operating time was 219 minutes; the average blood loss was less than 25 mL; resumption of an unrestricted diet, 27 hours; and mean hospital stay, 58 hours. Intraoperative technical complications occurred in five (9%) patients. One patient died during surgery from a sudden pulmonary embolus. Two (4%) patients required a second operation for recurrent paraesophageal hernias.

CONCLUSIONS

Laparoscopic repair of paraesophageal hiatal hernias is safe and effective, but the operation is difficult and good results hinge on details of the operative technique and the surgeon's experience. In this series, the crus could always be closed securely without using mesh. We realized early that a fundoplication should be a routine step, because it corrects reflux and is the best method to secure the gastroesophageal junction in the abdomen.

Assessing a virtual reality surgical skills simulator

The Institute for Defense Analyses (IDA) was contracted to perform a military standard task analysis of laparoscopic cholecystectomy, and to study the effectiveness of a virtual reality surgical skills simulator as a tool for surgical training and as a method for recording psychomotor behavior. This report describes the purpose of the study, its design, initial results, and implications for the field of medical education.

Early odor preference training increases olfactory bulb norepinephrine

In vivo microdialysis sampling of the olfactory bulbs of awake rats on PND 3 revealed that olfactory stimulation alone does not alter extracellular norepinephrine (NE) levels. Tactile stimulation that is designed to mimic maternal interactions with the young does increase bulb NE and the combined odor and tactile stimulation further increases NE levels. These data are consistent with a critical role for NE in the development of early olfactory preferences in infant rats, induced by odor/tactile stimulation pairings. PND 10 odor/tactile stimulation does not evoke an increase in NE, data consistent with the finding that odor preference training of this kind is ineffective after about the first week of life. Oral infusion of milk on PND 3 also increases bulb NE, a finding consistent with the role of milk as a reinforcing stimulus for the development of early olfactory preferences. Finally, infusion of potassium into the bulb on PND 3 produces a rapid increase in NE, indicating a local neuronal origin of the NE in response to stimulation.