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At least 1,117 records · Page 62Linked to original sources
PubMed1998

Induction and persistence of cytogenetic damage in mouse splenocytes following whole-body X-irradiation analysed by fluorescence in situ hybridization. IV. Dose response.

PURPOSE: To develop a mouse model for retrospective biological dosimetry, the kinetics of induction and persistence of chromosome aberrations following X-irradiation are analysed. MATERIALS AND METHODS: Female Swiss mice were whole-body exposed to 0, 0.5, 1.0, 2.0 or 3.0 Gy X-rays. Fluorescence in situ hybridization using composite DNA libraries specific for chromosomes 1, 11 and 13 was performed on metaphase chromosomes from isolated splenocytes at 0, 7, 28, 56, 112 and 224 days post irradiation to detect chromosome aberrations. RESULTS: Dose-response curves for all types of aberrations observed ¿dicentrics, fragments, metacentrics (Robertsonian fusion-like configurations) and translocations¿ were well fitted by a linear quadratic model. Equal induction of dicentrics and translocations was observed immediately after irradiation for all the doses used. The frequency of dicentrics and fragments decayed exponentially with time. Genomic translocation frequency declined with time post-irradiation and reached stability during later intervals, which was strongly dose-dependent. Reciprocal translocations and incomplete exchanges (terminal translocations) were induced at almost equal frequency immediately after X-irradiation (exception 3.0 Gy) and showed different patterns of decline. CONCLUSION: The results, on the decay of genomic translocation frequency with time after irradiation in mouse splenocytes, have implications on the use of translocations in retrospective biological dosimetry.

Animals↗
PubMed1983

Satellite DNA from Xenopus laevis: comparative analysis of 745 and 1037 base pair Hind III tandem repeats.

Highly repetitive Hind III restriction fragments of 0.72-0.76 KBP from total Xenopus laevis genomic DNA are organized in a tandem like arrangement. Cloning of these fragments in pBR 322 with subsequent restriction site mapping and nucleotide sequence analysis of some selected clones showed two different types of sequences. 25-30% of material represent the oocyte specific 5 S DNA repeat units, 70-75% are similar to the recently described repeat elements of satellite 1 DNA. Hybridization of a genomic DNA library to such a 745 BP monomeric repeat unit and investigation of some clones with positive autoradiographic signals revealed structural heterogeneities of repeat elements, in that the 745 BP sequence cross-hybridized with 1037 BP Hind III repeat units. Nucleotide sequence analysis demonstrated that the two types of sequences show a homology of 84.3% and that the 1037 BP sequence additionally contains duplicated elements of the 745 BP sequence as well as apparently unrelated DNA sequences.

Animals↗
PubMed2003

Embolized crospovidone (poly[N-vinyl-2-pyrrolidone]) in the lungs of intravenous drug users.

Crospovidone is an insoluble polymer of N-vinyl-2-pyrrolidone that is used as a disintegrant in pharmaceutical tablets. It can potentially embolize to the lung when aqueous tablet suspensions are injected intravenously. In this report, we identified embolized crospovidone in autopsy-derived lung tissue from three adult IV drug users, 1 man and 2 women, whose ages respectively were 27, 38, and 40 years. Suspected crospovidone was compared with pharmaceutical-grade crospovidone by means of histochemical stains, transmission electron microscopy, and infrared spectroscopy. Similar particles were also observed by light microscopy in a 4-mg tablet of hydromorphone, a preparation prescribed to two of the patients. Two patients had sickle cell disease and were taking methadone and/or hydromorphone for pain management; the third was receiving parenteral hyperalimentation after small bowel resection. Crospovidone appeared as deeply basophilic, coral-like particles within pulmonary arteries and in extravascular foreign-body granulomas. Intrapulmonary crospovidone stained similarly to the pure substance, including intense staining with mucicarmine, Congo red, and Masson trichrome. With Movat pentachrome stain, both intravascular and purified crospovidone appeared orange-yellow, whereas most interstitial particles associated with giant cells stained blue-green. Alcian blue failed to stain intravascular or purified crospovidone but strongly decorated some phagocytized particles. Ultrastructurally, both purified powder and tissue deposits of crospovidone appeared as irregular, electron dense, laminated, and finely granular material. Intrapulmonary crospovidone was associated with inflammatory cells and exhibited degenerative changes. By infrared spectroscopy, crospovidone in tissue had the same spectral characteristics as pharmaceutical grade crospovidone and the library reference, polyvinylpyrrolidone (PVP). We conclude that crospovidone contributes to pulmonary vascular injury in some persons who illicitly inject pharmaceutical tablets. It is readily identifiable histologically and distinguishable from other tablet constituents, such as cornstarch, talc, and microcrystalline cellulose. The variable staining with Alcian blue and Movat suggests that crospovidone is altered in vivo by the inflammatory response.

Adult↗
PubMed1996

The telomeric and centromeric ends of HLA class I: MCD maps of YAC derived cosmids and sequence analysis of 740 kb of genomic DNA.

We previously isolated and characterized a set of overlapping yeast artificial chromosome (YAC) clones spanning 2.4 Mb, including the entire MHC class I region, as a first step towards a detailed genetic analysis. We report here the genomic sequence of the two ends of HLA class I. The centromeric portion of HLA class I, extending from TNF to HLA-C was determined using two different sources of genomic DNA. As a first source, we sequenced cosmids (provided by T. Spies) derived from a total human DNA library which were mapped with conventional restriction digestion and fingerprinting. A second more generalizable approach was used to obtain cosmids for the remainder of the region. The new technology of Multiple-Complete-Digest (MCD) mapping, developed in Maynard Olson's laboratory, was used to map cosmids derived from YACs. This technique involves screening deep cosmid libraries derived from selected YACs and subjecting the cosmids to complete digestion with restriction enzymes, followed by computational assembly into completed maps. This method was also used to obtain material for sequence from three overlapping YACs covering a contiguous region from HLA-G to a point 330 kb telomeric. Among the plethora of new genetic information is a detailed picture of the organization of new multigene families contained within the telomeric end and of members of families spread throughout HLA class I. A clear relationship between the telomeric and centromeric ends of HLA class I has been defined, suggesting that large portions of these regions derived from a common ancestor. Our results demonstrate genomic sequencing to be one of the most effective and efficient means of identifying new genes, yielding information about genomic structure, regulation, and offering new insights into the meaning of physical relationships among functionally interacting genes.

Centromere↗
PubMed2006

[Complications of peripheral nerve blocks].

Recent years have brought renewed interest in peripheral nerve blocks as new drugs and materials have become available and as the advantages of such blocks over other anesthetic and analgesic techniques have been demonstrated. We conducted a literature search in PubMed, the Cochrane Library Plus (Spanish version), and Healthgate for the period January 1, 2000 through October 15, 2005 using the key words "complication and peripheral nerve block," "complication and peripheral block anaesthesia," and "complication and plexus anaesthesia." Totals of 178, 109, and 145 titles were obtained with each portal. When the search was limited to reviews, clinical trials, and randomized controlled trials, the numbers of articles from each portal became 11, 20, and 10, respectively, for the first string of key words; 0, 8 and 6, respectively, for the second string; and 10, 40 and 16 for the third. A detailed analysis of the results revealed 2 reviews and 1 clinical trial in which complications of peripheral nerve blocks figured in the main topic. Most of these publications agree that the overall incidence of complications related to these techniques is low. If practice guidelines and algorithms from experts are followed the incidence can be reduced. The aim of this review is to give an updated report of complications related to peripheral nerve blocks.

Algorithms↗
PubMed1993

Use of a sensitive fluorescent intercalating dye to detect PCR products of low copy number and high molecular weight.

The ability to routinely and specifically amplify and detect PCR products ranging in size from < 1 to > 10 kb, regardless of target template sequence or structure, would facilitate several tasks in human genome research. Generation of a wide size range of PCR products would potentially expedite isolation of uncloned DNA (gaps) represented in physical maps and provide a means for maintaining order and orientation of closely linked loci during analysis. Long-range PCR offers an alternative to isolation of genomic or cDNA clones from tissues or species where appropriate libraries are unavailable. This methodology also provides a powerful strategy to pursue directed transposon-based mapping and sequencing of templates of 100 kb or greater. Further development of basic PCR technology has been necessary in order to make it feasible to use large DNA targets as primary templates for genome analysis. Application of these extended PCR capacities would potentially save time, materials, and cost.

Bacteriophage lambda↗
PubMed2004

Sample size, library composition, and genotypic diversity among natural populations of Escherichia coli from different animals influence accuracy of determining sources of fecal pollution.

A horizontal, fluorophore-enhanced, repetitive extragenic palindromic-PCR (rep-PCR) DNA fingerprinting technique (HFERP) was developed and evaluated as a means to differentiate human from animal sources of Escherichia coli. Box A1R primers and PCR were used to generate 2,466 rep-PCR and 1,531 HFERP DNA fingerprints from E. coli strains isolated from fecal material from known human and 12 animal sources: dogs, cats, horses, deer, geese, ducks, chickens, turkeys, cows, pigs, goats, and sheep. HFERP DNA fingerprinting reduced within-gel grouping of DNA fingerprints and improved alignment of DNA fingerprints between gels, relative to that achieved using rep-PCR DNA fingerprinting. Jackknife analysis of the complete rep-PCR DNA fingerprint library, done using Pearson's product-moment correlation coefficient, indicated that animal and human isolates were assigned to the correct source groups with an 82.2% average rate of correct classification. However, when only unique isolates were examined, isolates from a single animal having a unique DNA fingerprint, Jackknife analysis showed that isolates were assigned to the correct source groups with a 60.5% average rate of correct classification. The percentages of correctly classified isolates were about 15 and 17% greater for rep-PCR and HFERP, respectively, when analyses were done using the curve-based Pearson's product-moment correlation coefficient, rather than the band-based Jaccard algorithm. Rarefaction analysis indicated that, despite the relatively large size of the known-source database, genetic diversity in E. coli was very great and is most likely accounting for our inability to correctly classify many environmental E. coli isolates. Our data indicate that removal of duplicate genotypes within DNA fingerprint libraries, increased database size, proper methods of statistical analysis, and correct alignment of band data within and between gels improve the accuracy of microbial source tracking methods.

Animals↗
PubMed1978

The on-line user network: organization and working procedures.

The National Library of Medicine's on-line user community has grown from a small group of 25 institutions in October 1971 to more than 900 in January 1978. Management of the MEDLINE User Network, co-ordination of on-line data-bases, and provision of user support services are an important function of the MEDLARS Management Section (MMS). MMS is the point of contact for on-line users; a service desk is maintained to provide immediate assistance; and technical materials describing the various data-bases are prepared including the monthly NLM Technical Bulletin and the On-Line Services Reference Manual. Other management and support activities include the preparation of statistical reports; handling of on-line centre applications received from the Regional Medical Libraries; co-ordination of codes and passwords for users; and the distribution of off-line prints, off-searches, and tape copies of the data-bases. A monthly current awareness service is also provided. The working procedures for these support activities are described.

Fees and Charges↗
PubMed2001

Kava extract for treating anxiety.

BACKGROUND: Synthetic anxiolytic drugs are effective for anxiety, but they are burdened with adverse events. Constraints on resources and time often render treatments such as psychological interventions impracticable. Thus, an effective and safe oral medication would be of considerable interest and a welcome addition to the therapeutic repertoire. OBJECTIVES: To systematically review the evidence regarding the efficacy and safety of kava extract for the symptomatic treatment of anxiety. SEARCH STRATEGY: Computerized literature searches were performed in the databases Medline, Embase, Biosis, AMED, CISCOM and the Cochrane Library (all from their respective inception to June 1998). The search terms used were kava, kawa, kavain, Piper methysticum and Rauschpfeffer (German common name for Piper methysticum). Manufacturers of kava preparations and experts on the subject were contacted and asked to contribute published and unpublished material. In addition, our own files were searched and the bibliographies of all of the studies identified were scanned for further trials. There were no restrictions regarding the language of publication. SELECTION CRITERIA: Randomized, double-blind trials of oral kava extract mono-preparations for the treatment of anxiety were included. Trials comparing kava with placebo were included. Trials assessing kava as one of several active constituents in a combination preparation or as a part of a combination treatment were excluded. DATA COLLECTION AND ANALYSIS: All publications were blinded prior to assessment by a person not involved in the study. Data on patients, interventions, methods, results and adverse events were extracted systematically. Methodological quality of all trials was evaluated using the scoring system developed by Jadad and colleagues. The screening of studies, selection, data extraction and the assessment of methodological quality were performed independently by the two reviewers. Disagreements in the evaluation of individual trials were resolved through discussion. MAIN RESULTS: Seven trials met the inclusion criteria. All of the reviewed trials suggest superiority of kava extract over placebo. The meta-analysis of three studies using the Hamilton Anxiety Score as a common outcome measure suggests a significant differential treatment effect in favour of kava extract (weighted mean difference: 9.69, 95% confidence interval: 3.54 - 15.83). Adverse events as reported in the reviewed trials were mild, transient and infrequent. REVIEWER'S CONCLUSIONS: These data imply that kava extract is superior to placebo and relatively safe as a symptomatic treatment for anxiety. These findings warrant further and more rigorous investigations into the efficacy and safety of kava extract.

Anxiety↗
PubMed2006

Finite element analysis of the strain distribution in the humeral head tubercles during abduction: comparison of young and osteoporotic bone.

AIM: The aim of this work was to design an accurate 3D digital model of the humerus and rotator cuff muscles. This model was then used to study strain distribution in humeral tubercles according to bone density. MATERIALS AND METHODS: The geometry of bone and muscle structures was reproduced using SURFDRIVER software, based on anatomical sections, CT scans and MRI images from the Visible Human Project image library. The contours were transferred to PATRAN software to rebuild volumes and mesh them. Calculations of strains and their distribution were performed using NASTRAN software. All the elements were considered to be isotropes. RESULTS: The study of the distribution of stress magnitude according to the type of bone modeled, shows that some stresses in cortical bone are greater than those in cancellous bone and are also greater in old bone, implying more deformation in old bone at constant force. This study also shows that stresses do not penetrate deeply into cancellous tissue. CONCLUSION: Observing the simulation results led understanding of the pathology of certain fractures of the proximal end of the humerus. This study also helped explain why certain types of osteosynthesis fail due to tubercles reconstruction failures.

Bone Density↗
PubMed2003

Pharmacological effects of Cimicifuga racemosa.

Cimicifuga racemosa is widely employed to relieve menopause symptoms for its hormonal-like action. However, recent experimental studies have not found an estrogenic action by this plant. The purpose of this systematic review is to analyse all experimental studies (in vivo and in vitro) performed on C. racemosa to elucidate its mechanism of action. Animal and in vitro experiments on C. racemosa were identified through a computerised literature searches performed on Medline (PubMed), Embase, Amed, CISCOM and Cochrane Library databases. In addition, bibliographies of the articles thus located were scanned for further relevant publications and manufactures of commercial C. racemosa preparations were asked to contribute published and unpublished material. No language restrictions were imposed. A total of 15 animal and 15 in vitro studies on C. racemosa have been found. Their results suggest that C. racemosa possesses a central activity instead of a hormonal effect. Further biological and chemical investigations are required to define its mechanism of action and to identify the compounds responsible of its actions.

Animals↗
PubMed2001

Simulation of Space Shuttle neutron measurements with FLUKA.

FLUKA is an integrated particle transport code that has enhanced multigroup low-energy neutron transport capability similar to the well-known MORSE transport code. Gammas are produced in groups but many important individual lines are specifically included, and subsequently transported by the main FLUKA routines which use a modified version of EGS4 for electromagnetic (EM) transport. Recoil protons are also transported by the primary FLUKA transport simulation. The neutron cross-section libraries employed within FLUKA were supplied by Giancarlo Panini (ENEA, Italy) based upon the most recent data from JEF-1, JEF-2.2, ENDF/B-VI, JENDL-3, etc. More than 60 different materials are included in the FLUKA databases with temperature ranges including down to cryogenic temperatures. This code has been used extensively to model the neutron environments near high-energy physics experiment shielding. A simulation of the Space Shuttle based upon a spherical aluminum equivalent shielding distribution has been performed with reasonable results. There are good prospects for extending this calculation to a more realistic 3-D geometrical representation of the Shuttle including an accurate representation of its composition, which is an essential ingredient for the improvement of the predictions. A proposed project to develop a combined analysis and simulation package based upon FLUKA and the analysis infrastructure provided by the ROOT software is under active consideration. The code to be developed for this project will be of direct application to the problem of simulating the neutron environment in space, including the albedo effects.

Aluminum↗
PubMed2001

Facile three-component coupling procedure for the synthesis of substituted tetrahydroisoindole-1,3-diones from alpha,beta-unsaturated aldehydes.

[reaction: see text]. A new one-pot procedure for the efficient synthesis of a small library of amino-functionalized tetrahydroisoindole-1,3-dione derivatives was developed. This three-component coupling reaction comprises subsequent condensation and Diels-Alder reactions of ubiquitous available starting materials (alpha,beta-unsaturated aldehydes, amide, and maleimide). The synthesized compounds share a substituted tetrahydroisoindole motif in an endo fashion.

Journal Article↗
PubMed2005

Molecular genetics using T-DNA in rice.

Now that sequencing of the rice genome is nearly completed, functional analysis of its large number of genes is the next challenge. Because rice is easy to transform, T-DNA has been used successfully to generate insertional mutant lines. Collectively, several laboratories throughout the world have established at least 200,000 T-DNA insertional lines. Some of those carry the GUS or GFP reporters for either gene or enhancer traps. Others are activation tagging lines for gain-of-function mutagenesis when T-DNA is inserted in the intergenic region. A forward genetic approach showed limited success because of somaclonal variations induced during tissue culture. To utilize these resources more efficiently, tagged lines have been produced for reverse genetics approaches. DNA pools of the T-DNA-tagged lines have been prepared for polymerase chain reaction (PCR) screening of insertional mutants in a given gene. Appropriate T-DNA insertion sites are determined by sequencing the region flanking the T-DNA. This information is then used to make databases that are shared with the scientific community. International efforts on seed amplification and maintenance are needed to exploit these valuable materials efficiently.

DNA, Bacterial↗
PubMed2005

Factors associated with academic radiology research productivity.

PURPOSE: To determine factors associated with research productivity among all university radiology departments in the United States. MATERIALS AND METHODS: As an observational study, this was exempt from institutional review board approval. All 47,299 radiology articles from 1996 through 2003 that were indexed in the National Library of Medicine MEDLINE database were studied. Each article was assigned a "publication impact" score based on the impact factor of its source journal. These citations were then matched, along with National Institutes of Health (NIH) extramural grant, residency, fellowship, faculty, and geographic data, to 109 individual medical school radiology departments. Raw citation count was used to measure research quantity, and aggregate publication impact was used to measure quality. Regression analyses were used to compare the relationship between the study variables and research quality and quantity measures on the departmental and individual faculty level. RESULTS: Finalized statistical models accounted for 75%-88% of variance in productivity. NIH funding had a significant and positive association with all measures of research productivity (P < .001), with one article associated with 167,980 dollars in funding and one publication impact unit associated with 83,271 dollars in funding. Large resident program sizes (P < .001) and the presence of fellows (P = .007) also had a significant association. Geographic region, salary, and faculty characteristics had no detectable association. Extrapolations based on these results estimated the cost of annual global radiology research at 907 million dollars, with the U.S. component at at least 417 million dollars. NIH funding accounted for 45% of the U.S. component. CONCLUSION: NIH funding, resident program size, and fellow characteristics are significantly associated with academic research output.

Bibliometrics↗
PubMed2000

Antineoplastic agents from natural sources: achievements and future directions.

The influence of natural products upon anticancer drug discovery and design cannot be overestimated. Approximately 60% of all drugs now in clinical trials for the multiplicity of cancers are either natural products, compounds derived from natural products, contain pharmacophores derived from active natural products or are 'old drugs in new clothes', where (modified) natural products are attached to targeting systems. This review covers those materials that the authors are aware of as being in clinical trials through early 2000 and demonstrates how, even today, in the presence of massive numbers of agents from combinatorial libraries, the compounds produced by 'Mother Nature' are still in the forefront of cancer chemotherapeutics as sources of active chemotypes.

Animals↗