bluuebunny/crossref_metadata_2025 huggingface dataset:
Hamsters and Gerbils: Advantages and Disadvantages as Models in Toxicity Testing
Authors: Homburger F. , Dongen C. G. Van , Adams R. A. , Soto E.
Published: April 2009

The need for additional species of laboratory animals for toxicity testing, especially for chronic (lifetime) carcinogenesis bioassay, becomes more apparent as data on such tests in mice and rats accumulate and undergo analysis. The results of approximately half of the lifetime carcinogenesis bioassays conducted by the National Cancer Institute and the National Toxicology Program were either equivocal or unevaluable. Some changes must, therefore, be considered for carcinogenesis bioassay guidelines, and foremost among such improvements would be the inclusion of a species with few spontaneous tumors, healthy parenchymal organs (especially liver), and proven susceptibility to administered standard carcinogens and other substances known to be carcinogenic to man or other laboratory animals. Mesocricetus auratus, the Syrian golden hamster, is such a species. A considerable body of background information on Syrian hamsters is available and continues to accumulate in the literature. Information on gerbils (Meriones unguiculatus) is less voluminous, but that which is known suggests that this species as well could contribute toward improvement in toxicological and carcinogenesis bioassays. There are some limitations, however, which apply to gerbils, namely, a much longer lifespan than most other laboratory rodents, fairly high frequency of spontaneous tumors, and great diversity in the nature of such naturally occurring tumors. Gerbil population genetics has been studied less thoroughly. Inbred Syrian hamsters and their genetically defined hybrids, standardized for carcinogenesis responsiveness, healthy and long-lived, are now readily available, making it possible to reproduce results at any time in different laboratories.
Image Analysis Quantitation of Type 2 Cells and Alveolar Walls Part I: Influence of Time on the Developing Mouse Lung
Authors: Sherwin R. P. , Richters V.
Published: April 2009

Quantitative measurements of the lungs of Swiss-Webster male mice at 6, 10, and 16 weeks of age were obtained using image analysis. The measurements included numbers and area of type 2 cells, and the area, perimeters, and linear intercepts of alveolar walls. In addition, type 2 cell:alveolar wall ratios were used to compare cell and alveolar wall interrelationships with time. The most outstanding of the findings was a 21.8% increase in mean type 2 cell area with time (6 weeks vs. 16 weeks of age; P < 0.05), with only a relatively slight increase (6.3%) in the number of type 2 cells. Type 2 cell (≥ 12 μm) number also increased at 16 weeks of age (P < 0.06). Accompanying the increases in cell size and number was an increase in alveolar wall area (25.6%, or 21.4% with the type 2 cell field area excluded). Since the wall area increase was less than that for type 2 cell field area or type 2 cell mean area but greater than the type 2 cell number increase, there were disparate trends in the ratios comparing cell area and cell number to alveolar wall area. Significantly, type 2 cell numbers, mean type 2 cell area, and alveolar wall area had not plateaued at 16 weeks of age. Thus, there is the implication that the type 2 cell population and the alveolar walls are still undergoing changes at least up to the age of 10 weeks and possibly beyond 16 weeks of age. This is a longer period of lung development than expected from prior literature reports and raises the question of a correspondingly greater period of increased susceptibility to noxious air pollutants. An influence of an ambient level of NO2 exposure on the developing mouse lung is the subject of Part II of this investigation.
Image Analysis Quantitation of Type 2 Cells and Alveolar Walls Part II: Influence of 0.3 ppm Nitrogen Dioxide Exposure on the Developing Mouse Lung
Authors: Sherwin R. P. , Richters V. , Richters A.
Published: April 2009

Newborn male mice (45 control and 45 experimental) were tested after 6 weeks of 0.3 ppm nitrogen dioxide (NO2) exposure and at postexposure periods of 4 and 10 weeks. After 6 weeks of exposure, there was a 12.9% increase in type 2 cell number that was statistically significant (P < 0.025) and an 11% increase in mean type 2 cell area that fell short of statistical significance. The ratio of cell area to alveolar wall area was also statistically significant (P = 0.05). The latter ratio, dividing a combined measurement of numbers and area of type 2 cells (type 2 cell field area) by the alveolar wall area, serves to control for lung volume. Although increases in type 2 cell number were not statistically significant for the 2 postexposure test periods, a significant increase (P < 0.05) was found by analysis of variance for all 3 test periods. NO2 exposure also resulted in a significant interaction (group x time; P < 0.05) of the type 2 cell field area:alveolar wall area ratio, i.e., a progressive fall for the exposed animals vs. a progressive rise for the control group. The interaction is believed to be the result of NO2-induced type 2 cell swelling followed by impairment of normal type 2 cell growth. The increase in type 2 cell numbers most likely reflects damage to the type 1 cell population since type 2 cell hyperplasia is a common denominator for diverse kinds of human lung disease where damaged type 1 cells are replaced by type 2 cells. The finding of a statistically significant interaction of the type 2 cell field area:wall area ratio and the persistence of increased alveolar wall area imply that the effects of NO2 on type 2 cells and alveolar walls were not completely reversed 10 weeks after exposure. Should the effects be irreversible, there would be the further implication of a commensurate depletion of structural and functional reserves of the lung.
Sex and Age Differences in the Distribution of 14C-Sterigmatocystin in Immature and Mature Rats: A Multiple Dose Study
Authors: Walkow J. , Sullivan G. , Maness D. , Yakatan G. J.
Published: April 2009

Sterigmatocystin, a secondary fungal metabolite, produces a toxic reaction upon administration to experimental animals. Examination of rats that have received multiple doses of 14C-sterigmatocystin may indicate the response elicited by repeated exposure to foodstuffs containing the mycotoxin. Daily doses of sterigmatocystin, 8 mg/kg equally divided over 13 days, were administered in the feed. Immature rats (50–150 g) and mature rats (200–300 g) of both sexes were studied. On the 14th day, an 8 mg/kg dose of 14C-sterigmatocystin dissolved in wheat germ oil was orally intubated into the rats. Five rats of each sex and age group were sacrificed at 3, 6, 12, 24, 48, and 96 hours. Biological specimens were collected and analyzed for total radioactivity. Tukey's paired comparison procedure was used to analyze for statistically significant differences in tissue exposure to 14sterigmatocystin due to age and sex. Statistically significant differences in tissue levels were found in 60% or more of the tissues when comparing mature males vs. immature females and mature males vs. mature females. Age and sex differences were also observed in 45% or less of the tissues in other age or sex comparisons. The sterigmatocystin plasma levels vs. time curves contain multiple peaks that may indicate enterohepatic recirculation. The gradual decline in the log-linear phase resulted in long half-lives, ranging from 61.5 to 130 hours.
A Dual Function Exposure System for Acute Exposure of Mice to Chemical Vapors
Authors: Francovitch R. J. , George W. J.
Published: April 2009

A new and innovative portable system, allowing for the exposure of up to 24 mice to chemical vapors for a period of at least 4 hours, is presented. With this apparatus, mice can be selectively exposed to a chemical agent strictly by the dermal route or by inhalation. Specially designed animal cassettes or holders containing slots in the rear portion were developed for use in this system. These slotted areas in the holders provide adequate ventilation and permit mice to be exposed dermally to test substances. Operating parameters of the exposure system were evaluated with test atmospheres of ethylene dichloride (EDC). Distribution of vapor in the chamber was tested for 2 different concentrations of EDC, 500 ppm and 1200 ppm. Vapor distribution was found to be uniform throughout the chamber for both concentrations. The capability of the exposure system to maintain a consistent desired test atmosphere over a 4-hour period was also investigated. EDC was used at concentrations of 900 and 1000 ppm, and it was demonstrated that the EDC concentration varied by no more than ±8% over the test period. Thus, this exposure chamber represents an inexpensive, uniform, portable system for conducting inhalation or dermal exposure studies with selected contaminants that might represent a potential chemical hazard.
The Effect of T-2 Toxin on the Acute Phase Reaction in Mice
Authors: Dyck R. F. , Issa M.I.C. , Rogers S.L. , Murphy F. , Khachatourians G.G.
Published: April 2009

The effects of T-2 toxin on a murine model of the acute phase response were studied. Two murine acute phase reactants, serum amyloid P component and plasma fibronectin, were measured after subcutaneous and intraperitoneal administration of T-2 toxin in varying doses. No acute phase response was observed. Furthermore, T-2 toxin also blocked the acute phase reaction to subcutaneous AgNO3 in a dose-dependent fashion. These observations were not explained by damage to liver, the site of synthesis of acute phase proteins. Since the acute phase response is an immediate physiological reaction to tissue injury and may be a nonspecific participant in the repair phenomenon, its abrogation by T-2 toxin may contribute to the toxicity of this trichothecene mycotoxin.
Assessment of Possible Carcinogenic Risk to Humans Resulting from Exposure to Di(2-ethylhexyl)phthalate (DEHP)
Authors: Turnbull D. , Rodricks J. V.
Published: April 2009

The purpose of this work was to estimate the degree of risk that might be associated with human exposure to low levels of the plasticizer di(2-ethylhexyl)phthalate (DEHP). DEHP is a common component, sometimes at high concentrations, of polyvinyl chloride (PVC) plastics and was recently reported by the National Toxicology Program (NTP) to be carcinogenic in rats and mice, inducing hepatocellular tumors in both species. This work was also designed to illustrate an approach to risk assessment that attempts to incorporate all available biological data. Based on the dose-response data generated by the NTP bioassays, we have performed extrapolations of risk to low dose levels using several procedures, including some that incorporate inferences from the available data that shed light on the likely relationship between dose level and risk at low dose levels. In drawing these inferences, consideration was given to such factors as genotoxicity, metabolism and pharmacokinetics, and physiological and biochemical effects of DEHP that might reveal its mechanism of action. The relative merits of each of the various risk estimates are described, based on current understanding of DEHP's mode of biological action. It is concluded that DEHP's mechanism of carcinogenicity in rodents most likely involves its ability to induce peroxisome proliferation and related enzymatic changes, although other mechanisms cannot be excluded. If humans and rodents are assumed to be at the same risk at the same daily dose level of DEHP, application of the various low dose extrapolation models leads to the prediction that the daily dose resulting in a lifetime risk of no more than 1 in 1 million would be between 1.5 and 791 mg/kg per day, with the most likely figure being 116 mg/kg per day. If the carcinogenicity of DEHP is dependent upon its pattern of metabolism, however, it would be inappropriate to extrapolate from rodents to man without qualification because of the major quantitative differences in metabolism in rats, mice, and primates, including man. One of the major differences in metabolism of DEHP between rats and mice and primates is in production of a metabolite whose level may be an indicator of the level of peroxisomal activity and, hence, if the peroxisome proliferation theory of DEHP carcinogenicity is correct, of carcinogenic risk. However, the substantial doubt that exists regarding the applicability of rodent carcinogenicity data to humans must be expressed in qualitative terms.
Reproductive Toxicity Testing: Evaluating and Developing New Testing Systems
Authors: Lamb J. C.
Published: April 2009

Reproductive toxicity testing systems are used by national and international regulatory agencies. Protocols have not been standardized between agencies or even within certain agencies. Although there have been efforts at standardization, a certain amount of the differences between testing protocols is a reflection of the needs of the particular agency. New developments in in vitro techniques might lead to new test systems, but reproductive function is dependent upon the interaction of various cells and organs that cannot presently be copied in the test tube; this makes whole-animal testing systems a necessity. The present whole-animal models used by the Food and Drug Administration include the 3 segment reproduction studies used for testing drug safety and the multigeneration studies used for food additives. The Environmental Protection Agency has adopted 2 similar versions of a 2-generation study for the Office of Pesticide Programs and the Office of Toxic Substances. The National Toxicology Program, although not a regulatory agency, has taken a prominent role in reproductive toxicity testing, test system development, and test system evaluation. A new testing system, Fertility Assessment by Continuous Breeding (FACB), is currently being studied as a cost-effective and reliable alternative test system. The FACB protocol houses male and female mice as breeding pairs and removes offspring as soon as they are born during the first 14 weeks to allow continuous mating. Each breeding pair normally has up to 5 litters, and the last litter is saved to evaluate the second generation. The efficiency, reliability, and expense of the protocol are being compared to the existing testing systems.
Fertility Assessment by Continuous Breeding: Evaluation of Diethylstilbestrol and a Comparison of Results from Two Laboratories
Authors: Lamb J. C. , Jameson C. W. , Choudhury H. , Gulati D. K.
Published: April 2009

Diethylstilbestrol (DES) was selected as a positive control compound to study a new assay for reproductive toxicity testing. The assay, Fertility Assessment by Continuous Breeding, has been used at 2 different testing laboratories. This manuscript describes the results of 1 study and compares the reproducibility of the data from the 2 laboratories. CD-1 mice received a diet with DES at concentrations of 0, 1, 10, and 50 ppb (μg/kg) throughout the study. The treatment began 7 days before cohabitation, and then, for a 14-week period, the mice were housed as breeding pairs, and litters were weighed, sexed, and discarded to allow continuous matings. The males and females were separated at the end of 14 weeks, and the last litter was saved until weaning. The control pairs delivered an average of 4.75 litters per fertile pair, and 95% of the pairs had at least 1 litter. DES in feed at 50 ppb decreased fertility so that only 42% of the pairs were fertile, and the number of litters per fertile pair averaged only 1.38. Litter size and offspring survival were adversely affected by DES (50 ppb) in the diet. Data from the 2 laboratories performing these tests were similar, indicating that the studies were highly reproducible.
Subchronic and Chronic Toxicity Studies of 2,4-Dinitrotoluene. Part III. CD-1® Mice
Authors: Hong C.B. , Ellis H.V. , Lee C.C. , Sprinz H. , Dacre J.C. , Glennon J.P.
Published: April 2009

Subchronic and chronic toxicities of 2,4-dinitrotoluene (2,4-DNT) were evaluated in CD-1® mice. 2,4-DNT was more toxic to males than to females. Male mice fed 47 mg/kg per day or 137 mg/kg per day for 13 weeks gained less weight. However, females fed 52 or 147 mg/kg per day had no adverse effects. Feeding of 413 mg/kg per day for males or 468 mg/kg per day for females lowered feed consumption, depressed body weight, and caused mild anemia and mild hepatocellular dysplasia in both sexes and mild testicular degeneration in males. Both males and females were fed an average of 14 (low dose), 95 (middle dose), or 898 mg/kg per day (high dose) for up to 24 months. In males, there was a high incidence of epithelial renal tumor and hepatocellular dysplasia in all dose groups, Incidence of testicular atrophy was increased in the middle-and high-dose males. In addition, the high dose caused toxic anemia and death. In females, the high dose was associated with toxic anemia, hepatocellular dysplasia, nonfunctional follicle with a lack of corpora lutea, an effect analogous to the testiclar atrophy in males, and death. A generalized pigmentation, probably of 2,4-DNT metabolite origin, was seen in many tissues of especially the high-dose males and females.
Immunotoxicological Evaluation: An Overview
Authors: Norbury K.C.
Published: April 2009

Many new drug candidates being developed within the pharmaceutical industry possess immunological activity, which may eventually necessitate an evaluation of potential toxicity to the immune system. At present, no consensus exists on which immunotoxicological procedures are most suitable for incorporation into the routine toxicology studies. This paper describes a few immunological test procedures that seem feasible for extrapolating to man, since similar approaches are now used clinically to evaluate immune reactivity. At present, data demonstrating the efficacy of immunotoxicological assays have been limited to humans exposed to environmental contaminants.
Selenium Toxicity in Animals with Emphasis on Man
Authors: Olson O.E.
Published: April 2009

This review was undertaken to establish what might be the maximum safe dose of selenium that could be administered to man in studies on the use of the element in cancer prevention. The early history of selenium poisoning is briefly summarized. The literature on clinical signs and toxicity data for acute and for chronic selenosis in farm and experimental animals is discussed. Several cases of acute selenosis in man are reviewed, and a number of reports on chronic selenosis in man are reviewed and evaluated. Based on these, the maximum safe single oral dose of selenite, selenate, DL-selenocysteine, or DL-selenomethionine is suggested as 0.05 mg Se/kg body weight (milligrams of selenium per kilogram of body weight). The maximum safe multiple oral dose is suggested as 5 μg Se/kg body weight.
Effect of Dietary Selenite on Hepatic Organic Solvent-Soluble Lipofuscin Pigments
Authors: Csallany A.S. , Menken B.Z.
Published: April 2009

Supplementation of selenium as sodium selenite results in an increase in hepatic organic solvent-soluble lipofuscin pigments, the metabolic end products of lipid peroxidation. Weanling mice fed a basal diet containing 0.05 ppm selenium had a significant increase in hepatic organic solvent-soluble lipofuscin pigments and glutathione peroxidase activity following supplementation of an additional 0.1 ppm selenium as sodium selenite from 5 to 9 months of age. Normal levels of vitamin E (30 mg/kg) were insufficient to protect against the oxidative effect of this increased dose of selenite. However, 10 times the normal level of vitamin E markedly suppressed this oxidative effect.
The Role of Selenium Compounds in Cancer Therapy
Authors: Batist G. , Katki A.G. , Ferrans V.J. , Myers C.E.
Published: April 2009

Experimental evidence is presented that demonstrates the impact of selenium on the effects of a variety of anticancer treatments, including chemotherapy and radiation. Selenium-dependent glutathione peroxidase can detoxify organic peroxides resulting from some of these treatments. Selenium deficiency has also been associated with significant changes in liver enzymes that activate some drugs and contribute to detoxification. Some forms of free selenium have cytotoxicity against a variety of tumor cell lines, both murine and human. Experimental data suggest that catalytic oxidation of cellular glutathione and reduction of molecular oxygen are part of the mechanism of this antitumor activity. This provides provocative possibilities for the inclusion of selenium into cancer therapy regimens.
Some Comparative Aspects of Selenite and Selenomethionine Metabolism
Authors: Whanger P.D.
Published: April 2009

The different ratios of glutathione peroxidase (GPx) to selenium (Se) content in human erythrocytes as compared to those from animals are due to differences in the distribution of Se between the erythrocyte proteins, mainly GPx and hemoglobin (Hb). However, based on some rat experiments, this is probably not due solely to species differences but also to the dietary forms of Se consumed. When rats were fed diets with selenite as the Se source, essentially all of the Se was deposited with GPx, but when the source was selenomethionine, as supplied by high-Se wheat or selenized yeast, as much as 60% of the Se was deposited with Hb in the erythrocytes. Since the erythrocyte GPx activity is so low in comparison to the peroxidase activity of Hb, this creates a source of error in the assay of GPx in human blood, and thus this assay cannot be used to accurately assess Se status. When selenomethionine was the dietary source of Se for rats, significantly more Se was deposited in tissues (1.4 to 3.6-fold in liver, kidney, testis, blood, heart, and spleen), particularly the pancreas (8.5-fold) and muscle (10-fold), as compared to selenite as the Se source. Such data may be useful in designing experiments for testing the effectiveness of various Se compounds for cancer chemopreventive purposes.
Design and Validation of Computer Software for Teratology and Reproductive Toxicology Studies
Authors: Agnish N. D.
Published: April 2009

Computers have become very popular for collecting and analyzing data from toxicology studies. Software for this purpose is often written by individuals who may not be completely aware of the idiosyncrasies and peculiarities of toxicology data. This is particularly true of teratology and reproductive toxicology studies that have their own unique terminology whose definition often varies from laboratory to laboratory. Thus, it is essential that each laboratory spend some time in understanding the software that they have installed and subject it to a rigorous validation procedure to ensure that the software is doing the job that it was supposed to do and that the data are being properly collected and stored. A system of data entry and a set of procedures used to validate various programs in our laboratories are described.
Chronic Inhalation Toxicity of Fibrous Glass in Rats and Monkeys
Authors: Mitchell R. I. , Donofrio D. J. , Moorma W. J.
Published: April 2009

Numerous reports have shown that fibrous glass has the potential to cause fibrogenic and carcinogenic responses in test animals. The experiments producing significant response have, however, used unrealistic routes of exposure. The increased demand for fibrous glass for insulating purposes where respirable fibers may exist presents considerable concern for potential health problems. Therefore, a long-term inhalation study was conducted with F344 rats and cynomolgus monkeys exposed in treatments characterized by fibers of varying geometry and mass concentrations. A workweek type of exposure (7 hours/day, 5 days/week) was maintained for 18 months with monkeys and 21 months with rats, which were subsequently held to 80% mortality. The evaluation of response included life table analysis, body weights, clinical signs, hematological testing, respiratory function, ophthalmic examinations, clinical biochemical analysis, and gross and microscopic pathological examinations. Both species demonstrated pulmonary macrophage aggregates and granulomas containing fibrous glass. The rats had grossly visible pleural plaques, which were not seen in the monkeys. There was no evidence of pulmonary or mesothelial carcinogenicity or fibrogenicity in either species. There were no other significant responses with the exception of a statistically increased mononuclear cell leukemia in each fiber-exposed rat group.
Serotonin Content of the Lungs, Brains, and Blood of Mice Exposed to 0.45 ppm Nitrogen Dioxide
Authors: Sherwin R. P. , Shih J. C. , Lee J. D. , Ransom R.
Published: April 2009

Young adult male Swiss Webster mice were exposed to 0.45 ppm of nitrogen dioxide (NO2) for 7 hours per day for 4 weeks. The lungs and brains were assayed for serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) content by high-performance liquid chromatography. Lung 5-HT content for the exposed animals was 13.1% less than that for the control group, but this difference was not statistically significant. Brain 5-HT and 5-HIAA were significantly elevated, +17.3% (P < 0.005) and +47.3% (P 0.001), respectively, and the ratios of 5-HIAA to 5-HT were also higher (P 0.005). The results suggest that further exploration of lung and brain serotonin alterations by air pollutants may offer useful discriminates for the evaluation of air quality.
Testicular Effects Induced by Dermal or Inhalation Exposure to Para-tertiary Butyl Benzoic Acid (ptBBA) in Fischer 344 Rats
Authors: Lu C. C. , Cagen S. Z. , Darmer K. I. , Patterson D. R.
Published: April 2009

Testicular effects induced by dermal application or dust inhalation of para-tertiary butyl benzoic acid (ptBBA) in Fischer 344 rats were investigated. Similar effects were observed from both dermal and dust inhalation studies. Reduction in testis weights, testicular sperm head counts, and LDH-X enzyme levels were observed in a dose-related fashion. A reduction or absence of spermatogenic cell types, specifically spermatids and spermato-cytes in the seminiferous tubules, was observed histologically. In affected testes, some seminiferous tubules contained only Sertoli cells and few spermatogonia, whereas other tubules contained all stages of spermatogenic cells, except differentiating spermatids. Cell types sensitive to cytotoxic effects induced by ptBBA appeared to be the early spermatids and the late spermatocytes. Other cell types, late spermatids, earlier stages of spermato-cytes, and differentiating spermatogonia, were also affected in higher dosage groups. These affected cells were undergoing degeneration and may not survive through the course of spermatogenesis. However, most testes demonstrated partial damage with the presence of Sertoli cells and spermatogonia as compared to the control testes, and recovery following cessation of exposure would be anticipated.
Coenzyme Autocatalytic Network on the Surface of Oil Microspheres as a Model for the Origin of Life
Authors: Sharov Alexei  A.
Published: April 2009

Coenzymes are often considered as remnants of primordial metabolism, but not as hereditary molecules. I suggest that coenzyme-like molecules (CLMs) performed hereditary functions before the emergence of nucleic acids. Autocatalytic CLMs modified (encoded) surface properties of hydrocarbon microspheres, to which they were anchored, and these changes enhanced autocatalysis and propagation of CLMs. Heredity started from a single kind of self-reproducing CLM, and then evolved into more complex coenzyme autocatalytic networks containing multiple kinds of CLMs. Polymerization of CLMs on the surface of microspheres and development of template-based synthesis is a potential evolutionary path towards the emergence of nucleic acids.
Focal Conic Stacking in Smectic A Liquid Crystals: Smectic Flower and Apollonius Tiling
Authors: Meyer Claire , Le Cunff Loic , Belloul Malika , Foyart Guillaume
Published: April 2009

We investigate two different textures of smectic A liquid crystals. These textures are particularly symmetric when they are observed at crossed polars optical microscopy. For both textures, a model has been made in order to examine the link between the defective macroscopic texture and the microscopic disposition of the layers. We present in particular in the case of some hexagonal tiling of circles (similar to the Apollonius tiling) some numeric simulation in order to visualize the smectic layers. We discuss of the nature of the smectic layers, which permit to assure their continuity from one focal conic domain to another adjacent one.
Language-Based Access to Large Sensor Repositories
Authors: Baumann Peter
Published: April 2009

Sensor data have broadened their scope recently, ranging now from the simple time series measurements to, e.g., hyperspectral satellite image maps timeseries. In addition to observed data, simulation data increasingly have to be merged, for example 4-D ocean and atmospheric data. The majority of these data fall into the category of multi-dimensional rasters. However, when it comes to flexible retrieval, including sensor data search, aggregation, analysis, fusion, etc., standard query language support in the past has not kept up with the service level of, e.g., metadata retrieval. To close this gap, the Open GeoSpatial Consortium (OGC) has issued the Web Coverage Processing Service (WCPS) Standard in December 2008. WCPS defines a request language for multi-dimensional raster data, suitable for specifying navigation, download, and analysis of sensor, image, and statistics data. This contribution emphasises sensor data modeling and the perspectives for an integrated, cross-dimensional sensor data retrieval. Further, the WCPS reference implementation is briefly discussed.
Compact Integration of a GSM-19 Magnetic Sensor with High-Precision Positioning using VRS GNSS Technology
Authors: Martín Angel , Padín Jorge , Anquela Ana Belén , Sánchez Juán , Belda Santiago
Published: April 2009

Magnetic data consists of a sequence of collected points with spatial coordinates and magnetic information. The spatial location of these points needs to be as exact as possible in order to develop a precise interpretation of magnetic anomalies. GPS is a valuable tool for accomplishing this objective, especially if the RTK approach is used. In this paper the VRS (Virtual Reference Station) technique is introduced as a new approach for real-time positioning of magnetic sensors. The main advantages of the VRS approach are, firstly, that only a single GPS receiver is needed (no base station is necessary), reducing field work and equipment costs. Secondly, VRS can operate at distances separated 50-70 km from the reference stations without degrading accuracy. A compact integration of a GSM-19 magnetometer sensor with a geodetic GPS antenna is presented; this integration does not diminish the operational flexibility of the original magnetometer and can work with the VRS approach. The coupled devices were tested in marshlands around Gandia, a city located approximately 100 km South of Valencia (Spain), thought to be the site of a Roman cemetery. The results obtained show adequate geometry and high-precision positioning for the structures to be studied (a comparison with the original low precision GPS of the magnetometer is presented). Finally, the results of the magnetic survey are of great interest for archaeological purposes.
New Dielectric Sensors and Sensing Techniques for Soil and Snow Moisture Measurements
Authors: Stacheder Markus , Koeniger Franz , Schuhmann Rainer
Published: April 2009

Measurements of material moisture are essential in fields such as agriculture or civil engineering. Electromagnetic techniques, more precisely dielectric methods, have gained wide acceptance in the last decades. Frequency or Time Domain methods take advantage of the high dielectric permittivity of water compared to dry materials. This paper presents four new dielectric sensors for the determination of soil or snow water content. After a short introduction into the principles, both the hardware and operating mode of each sensor are described. Field test results show the advantages and potentials such as automatic measurement and profiling, state-of-ground detection or large-scale determination. From the results it follows that the presented sensors offer promising new tools for modern environmental research.
Kinetic analysis of experimental rabbit tumour and inflammation model with 18F-FDG PET/CT
Authors: Huang G. , Dong S. , Wan L. , Liu P.
Published: April 2009

Non-specific accumulation of 18F-FDG by both tumour and inflammatory lesions can make diagnostic analysis difficult. Our aim was to explore the difference in 18F-FDG uptake kinetics between tumour and inflammatory cells. To this end, we investigated VX2 tumour lesions and inflammatory lesions in rabbits. Methods: Six rabbits with VX2 tumour cells transplanted into one forelimb muscle and inflammatory lesions induced by turpentine oil in the contralateral forelimb were scanned for 60 minutes post 18F-FDG injection. Imaging data was analyzed with the standard 2-tissue-compartment model. Parameters, VB, Ki, K1, k2, k3, k4, were compared between tumour and inflammatory lesions. SUV and dual time scan methods were also compared in the experiment. Results: Time activity curves of VX2 tumour lesions showed a characteristic pattern of gradually increasing 18F-FDG uptake up to 60 min, whereas, 18F-FDG uptake in inflammatory lesions increased more slowly than in tumours. Parameters estimated from the uptake process showed that forward transport constant, K1, and influx constant, Ki, values in VX2 tumour lesions (0.186 ± 0.053 and 0.048 ± 0.014, respectively) was significantly higher than that in inflammatory lesions (0.129 ± 0.024 and 0.022 ± 0.007, respectively) (p < 0.05). In contrast, mean values of VB, k2, k3 and k4 derived from VX2 tumours were not significantly different from that of inflammatory lesions. SUVs at 60 minutes post 18F-FDG injection were also significantly higher in the VX2 tumor lesions than in the inflammatory lesions. Retention index (RI) was not significantly different between VX2 tumours and inflammatory lesions (1.134 ± 0.076 vs. 1.060 ± 0.058, p > 0.05). Conclusion: Different kinetic parameters (Ki, K1, k3) exist between inflammatory and tumour lesions.
The success of 131I ablation in thyroid cancer patients is significantly reduced after a diagnostic activity of 40 MBq 131I
Authors: Verkooijen R. B. T. , Stokkel M. P. M. , van Isselt J. W. , Verburg F. A.
Published: April 2009

Objective: Dosimetry studies have shown that activities of 131I as small as 10-20 MBq may cause a stunning effect. A result of this stunning effect may be a lower success rate of the ablative 131I therapy for differentiated thyroid carcinoma (DTC). The aim of this study was to determine whether pre-therapeutic uptake measurement with 40 MBq 131I causes a lower success rate of ablation. Design: retrospective chart review study. Patients, methods: In two hospitals the ablation protocols differed in one respect only: in the one hospital no diagnostic 131I was applied before ablation (group 1, n = 48), whereas in the other hospital a 24-h uptake-measurement with 40 MBq 131I was performed (group 2, n = 51). Included were all DTC patients without distant metastases who had undergone 131I ablation between July 2002 and December 2005, and who had returned for 131I follow-up. Successful ablation was defined as absence of pathological 131I uptake on diagnostic whole-body scintigraphy and undetectable thyroglobulin-levels under TSH stimulation. Results: Overall, ablation was successful in 31/48 patients (65%) in group 1 and in 17/51 patients (33%) in group 2 (p=0.002). Multivariate analysis showed that pre-therapeutic uptake measurement using 40 MBq 131I was an independant determinant for success of ablation (p = 0.002). Conclusions: After applying a diagnostic activity of 40 MBq 131I before ablation, the success rate of ablation is severely reduced. Consequently, the routine application of 131I for diagnostic scintigraphy or uptake measurement prior to 131I ablation is best avoided.
Myocardial perfusion scintigraphy 2007 in Germany
Authors: Burchert W. , Bengel F. M. , Zimmermann R. , vom Dahl J. , Schäfer W. , Schober O. , Schäfers M. , Lindner O.
Published: April 2009

Aim: This third survey of the working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine in cooperation with the working group Nuclear Cardiology of the German Cardiac Society was to deliver information on the procedures and in particular on the development of myocardial perfusion scintigraphy (MPS) from 2005 to 2007. Method: 370 questionnaires (222 private practices (PP), 117 hospitals (HO), 31 university hospitals (UH)) were evaluated. Results: MPS of 114,374 patients were reported, 83% were investigated with 99mTc-perfusion tracers. 76% [2006=74%] were performed in PP, 15% [2006=17%] in HO and 9% [2006=9%] in UH. Diabetics represented 21% of all MPS patients in 2007. Data of 215 institutions which participated all from 2005 to 2007 showed an increase in MPS of 2.3% (PP +6.8%, HO −4.5%, UH −18.2%). The type of stress was pharmacological in 27% [2006 = 27%]; 67% adenosine (of these 25% with exercise), 31% dipyridamole (of these 55% with exercise), and 2% dobutamine. Gated SPECT was performed in 47% [2006 = 42%] of all rest and in 44% [2006 = 39%] of all stress MPS. 61% [2006 = 83%] of all institutions did not apply perfusion scores. 20% [2006 = 24%] of the institutions reported changes in the use of MPS by competing methods. Conclusion: There is a small increase of MPS between 2005 and 2007 despite competing methods. Gated SPECT has experienced more acceptance, but is still underrepresented. As compared to the European average and general standards of MPS a considerable backlog accounts to pharmacological stress tests, gated SPECT and perfusion scores.
Diente de un gran dinosaurio terópodo (Allosauroidea) de la Formación Villar del Arzobispo (Titónico-Berriasiense) de Riodeva (España)
Authors: Royo-Torres R. , Cobos A. , Alcalá L.
Published: April 2009

Se describe un diente de dinosaurio terópodo de 98,3 mm de longitud apical hallado en el término municipal de Riodeva (Teruel). El diente ha sido localizado de forma aislada en un nivel de microconglomerados perteneciente a la Formación Villar del Arzobispo de edad Titónico-Berriasiense. La morfología del diente, comprimido labiolingualmente, con las carenas denticuladas que alcanzan la base de la corona distal pero no la mesial, y el tamaño del ejemplar permiten incluirlo dentro del clado Allosauroidea. La variabilidad existente entre los dientes de diferentes géneros de alosauroideos determina que sea prudente no asignarlo a un grupo concreto dentro de este clado.
Knotting of Nasogastric Tube Around a Nasotracheal Tube: An Unusual Cause of Hypercapnia in a 3-Month-Old Infant
Authors: Melki Imad , Matar Nayla , Maalouf Sabine , Rassi Simon
Published: April 2009

A 3-month-old boy was admitted to the intensive care unit because of septic shock; he required immediate intubation and placement of a nasogastric tube. A confirmatory chest radiograph showed that the nasogastric tube was looping in the hypopharynx and needed to be repositioned. During removal of the nasogastric tube, the infant experienced hypercapnia and respiratory distress. These complications were due to looping and knotting of the nasogastric tube around the nasotracheal tube.
Information Science
Authors: Debons Anthony
Published: April 2009

The sections in this article are

History

Professional Structure of Information Science

Professional Activity

Professional Publications

Theoretical Structure of Information Science
Microwave Amplifiers
Authors: Edwards M. Lee , Cheng Sheng
Published: April 2009

The sections in this article are

Bias Circuit

Device Characteristics

Basic Amplifier Relationships

Stability

Gain

Noise Considerations

Large‐Signal (Nonlinear) Amplifiers

Multidevice Combinations

Design Examples
Microwave Circuits
Authors: Gupta K. C. , Cebi Haki , Cho Choonsik , Feng Zhiping
Published: April 2009

The sections in this article are

Types of Microwave Circuits

Lumped and Distributed Circuits

Evolution of Microwave Circuits

Waveguide Circuits

Coaxial Line Circuits

Stripline Circuits

Microstrip Circuits

Coplanar Waveguide Circuits

Lumped‐Element Circuits

Multilayer Microwave Circuits

Design of Microwave Circuits

Emerging Trends In Microwave Circuits
Microwave Heating
Authors: Osepchuk John M.
Published: April 2009

The sections in this article are

Basic Principles of Microwave Heating

Microwave Applicators

Practical Microwave Heating Systems

Power Source Properties

Safety Considerations

Future Advances in Microwave Heating
Microwave Parametric Amplifiers
Authors: Faber Marek T.
Published: April 2009

The sections in this article are

Principle of Operation

Varactor Diodes

Nondegenerate Parametric Amplifier

Other Parametric Amplifier Configurations

Illustrative Example
Monolithic Microwave Integrated Circuits
Authors: Bahl Inder J.
Published: April 2009

The sections in this article are

MMIC Fabrication

MMIC Substrates

Transmission Lines

MMIC Active Devices

Components and Circuits

MMIC Design

EM Simulators

Modeling

Typical Circuits and Performance

MMIC Packaging
Soft Langmuir–Blodgett Technique for Hard Nanomaterials
Authors: Acharya Somobrata , Hill Jonathan P. , Ariga Katsuhiko
Published: April 2009

Materials and their assemblies of dimensions down to a few nanometers have attracted considerable scientific interest in physical, chemical, and biological sciences because of unique properties not available in their bulk counterparts. The Langmuir–Blodgett (LB) technique allows rigid nanomaterials to be aligned in particular structures through a flexible assembly process at liquid interfaces. In this review, we summarize the development of assembly of hard nanomaterials using soft LB techniques. An initial summary of the basic features of nanomaterials will include dimension‐related effects, synthesis, characterization, and analysis, and will be followed by examples of LB assemblies of nanomaterials described according to their morphology: nanoparticles, nanorods, nanowires, nanotubes, and nanosheets. Some of the nanomaterials have been fabricated in orientation‐controlled morphologies, and have been incorporated into prototype devices for gas sensing and photocurrent transport. In the final part of this review, the challenges remaining for LB techniques of hard nanomaterials will be overviewed, and will include a comparison with the widely‐used LB technique involving soft materials.
Carbon fiber composites cured by γ‐radiation‐induced polymerization of an epoxy resin matrix
Authors: Dispenza C. , Alessi S. , Spadaro G.
Published: April 2009

The use of ionizing radiation in order to initiate polymerization of suitable monomers has found increased interest in the last two decades due to its several advantages. In this work, carbon fiber composites through gamma radiation polymerization of epoxy matrices have been produced for aerospace and advanced automotive applications. Composite samples were produced by irradiation at room temperature using different radiation doses and, as reference, thermal curing of the same epoxy resin formulations was also carried out. Furthermore, some irradiated samples were subjected to postirradiation thermal curing to complete the polymerization reactions. The properties of the cured materials were studied by dynamic mechanical thermal analysis and mechanical flexural tests. Also the effect of moisture absorption on the thermal properties was investigated. The results indicate that irradiation at room temperature gives rise to different cross‐link densities of the epoxy matrix depending on the total absorbed dose. Postirradiation thermal treatment makes the materials more “homogeneous,” resulting also in a higher glass transition temperature. Moreover, thermal analysis performed on irradiated samples, cut in both parallel and perpendicular directions to the fibers, has shown fiber‐‐matrix interactions that are less intensive in comparison to thermally cured samples. The water absorption data show a plasticization effect of moisture on the epoxy matrix, causing a significant reduction of Tg. Flexural tests reveal a marked effect of postirradiation thermal curing on the less cross‐linked samples, reflecting the higher efficiency of the thermal treatment on more mobile reactive species. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:163–171, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20127
Synthesis and characterization of hybrid nanocomposites comprising poly(vinyl alcohol) and colloidal silica
Authors: Sarkar Mousumi De , Deb Paromita
Published: April 2009

Organic–inorganic hybrid composite films were developed using poly(vinyl alcohol) (PVA) and an aqueous dispersion of colloidal silica of initial particle size of 15–30 nm. The hybrid films, prepared with varied proportion of colloidal silica (10–90 phr), were found to be transparent, indicating the nanolevel dispersion of the inorganic component over the polymer. Morphological studies further revealed no significant agglomeration of the silica domains embedded into the polymer matrix. A depression in glass transition temperature of PVA is observed with increasing proportion of silica. The degree of crystallinity also showed a decreasing trend with increasing amount of silica. However, the composite films demonstrated superior mechanical performances, higher resistances to dissolution in boiling water, and lower permeability compared with virgin PVA, owing to the better interaction between PVA and silica as well as the reinforcing action of nanosilica particles in the polymer matrix. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:152–162, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20129
Physically and chemically modified polycarbonate by metal ion implantation
Authors: Nathawat Rashi , Vijay Y. K. , Kumar P. , Kulriya P. , Ganesan V. , Sathe V.
Published: April 2009

Changes in physical and chemical properties have been studied for polycarbonate (PC) implanted by 100 keV Ni+ with various fluences from 1 × 1014 to 1 × 1016 ions/cm2. Changes in the surface morphology and composition have been observed with atomic force microscopy and X‐ray diffraction (XRD). Ni particles as precipitates in PC were observed by cross‐section transmission electron microscopy at the 100‐nm depth. Ion implantation induces changes in the topography of PC as indicated by a dramatic increase in surface roughness with ion fluence. Implanted metal ions show direct evidence of compound formation on the surface. Chemical changes in the surface region have been observed by Raman spectroscopy and UV–vis spectroscopy. UV–vis absorption analysis indicates a drastic decline in optical band gap from 5.46 to 1.76 eV at an implanted dose of 1 × 1016 ions/cm2. It is shown that partial destruction of the original chemical bonding under ion implantation leads to the creation of new amorphous and graphite‐like structures, which are confirmed by Raman spectroscopy. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:143–151, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20130