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At least 649 records · Page 36Linked to original sources
PubMed2000

Diversity and community structure within anoxic sediment from marine salinity meromictic lakes and a coastal meromictic marine basin, Vestfold Hilds, Eastern Antarctica.

16S rDNA clone library analysis was used to examine the biodiversity and community structure within anoxic sediments of several marine-type salinity meromictic lakes and a coastal marine basin located in the Vestfolds Hills area of Eastern Antarctica. From 69 to 130 (555 total) 16S rDNA clones were analysed from each sediment sample, and restriction fragment length polymorphism (RFLP) and sequence analysis grouped the clones into 202 distinct phylotypes (a clone group with sequence similarity of >0.98). A number of phylotypes and phylotype groups predominated in all libraries, with a group of 10 phylotypes (31% of clones) forming a novel deep branch within the low G+C Gram-positive division. Other abundant phylotypes detected in several different clone libraries grouped with Prochlorococcus cyanobacteria, diatom chloroplasts, delta proteobacteria (Desulfosarcina group, Syntrophus and Geobacterl Pelobacter/Desulphuromonas group), order Chlamydiales (Parachlamydiaceae) and Spirochaetales (wall-less Antarctic spirochaetes). Most archaeal clones detected (3.1% of clones) belonged to a highly diverged group of Euryarchaeota clustering with clones previously detected in rice soil, aquifer sediments and hydrothermal vent material. Little similarity existed between the phylotypes detected in this study and other clone libraries based on marine sediment, suggesting that an enormous prokaryotic diversity occurs within marine and marine-derived sediments.

Antarctic Regions↗
PubMed2002

Synthetic peptides identified from phage-displayed combinatorial libraries as immunodiagnostic assay surrogate quality-control targets.

BACKGROUND: Quantitative immunohistochemical (IHC) assays currently lack optimal reference quality-control material for cellular protein targets. To address this problem, we identified peptides that mimic the site on the native analyte to which the primary (monoclonal) antibody binds and used them as surrogate peptide controls. METHODS: We identified peptide candidates from a combinatorial peptide phage-display library that mimic the epitope for the 1D5 estrogen receptor (ER) monoclonal antibody (mAb). The peptide inserts of the phage clones were sequenced. Several phage-encoded peptides were then synthesized and analyzed for affinity and specificity. RESULTS: We identified phage clones that specifically bound to the ER 1D5 mAb. The binding was specific, in that the phage clones did not bind to two other isotype-matched mAbs. Their ability to bind the ER 1D5 mAb was related to the presence of a consensus sequence. Binding analysis revealed a K(d) of 8.3 x 10(-8) mol/L. The peptide was not recognized by any of 15 other mAbs commonly used for clinical IHC testing. Moreover, the peptide was able to inhibit the binding of ER 1D5 mAb to native ER, indicating that the peptide bound to ER 1D5 mAb at or close to the antigen-binding site. CONCLUSIONS: Surrogate peptide controls behave like the native analyte in terms of affinity and specificity. This technology may be especially useful when the native analyte is in short supply.

Amino Acid Sequence↗
PubMed2005

Discovery of a sulfated tetrapeptide that binds to vascular endothelial growth factor.

Molecules that mimic the sulfated glycosaminoglycan heparin and bind to heparin-binding growth factors would serve as important building blocks for synthetic biomaterials, e.g. to create a growth factor reservoir within a matrix. Peptide-based heparin mimetics would be particularly attractive, given the ease of peptide synthesis and modification. A sulfated tetrapeptide that fits this description and binds to vascular endothelial growth factor (VEGF) was discovered using a rationally-designed combinatorial approach. A approximately 6600 member library of tetrapeptides, designed to include heparin functionality, was synthesized by solid-phase Fmoc chemistry. The library was analyzed on-resin for VEGF binding using a fluorescence assay that employed a 7-amino-4-methylcoumarin-modified VEGF(165). The beads were ranked according to fluorescent signal and SY(SO(3))DY(SO(3)) was identified as the top binder. The binding affinity of the peptide for VEGF(165) was ascertained by surface plasmon resonance and compared with the heparin mimic suramin; the peptide binds to VEGF(165) 100-fold stronger than the sulfonated compound. These results suggest that the identified peptide may be useful in biomaterial applications where binding of VEGF is desired.

Binding Sites↗
PubMed1993

Characterization of de novo duplications in eight patients by using fluorescence in situ hybridization with chromosome-specific DNA libraries.

Fluorescence in situ hybridization (FISH) with chromosome-specific DNA libraries was performed on samples from eight patients with de novo chromosomal duplications. In five cases, the clinical phenotype and/or cytogenetic evaluations suggested a likely origin of the duplicated material. In the remaining three cases, careful examination of the GTG-banding pattern indicated multiple possible origins; hybridization with more than one chromosome-specific library was performed on two of these cases. In all cases, FISH conclusively identified the chromosomal origin of the duplicated material. In addition, the hybridization pattern was useful in quantitatively delineating the duplication in two cases.

Aneuploidy↗
PubMedDate not supplied

Approaching equity in consumer health information delivery: NetWellness.

The growing public interest in health and wellness information stems from many sources, including social changes related to consumers' rights and women's health movements, and economic changes brought about by the managed health care revolution. Public, hospital, and medical center libraries have been ill-equipped to meet the increasing need for consumer-oriented materials, even though a few notable programs have been established. The "Information Superhighway" could be an effective tool for sharing health information if access to telecomputing equipment and training were available to those with an information need. The University of Cincinnati Medical Center, with its libraries in the leading role, is delivering NetWellness, an electronic consumer health library service, to residents of 29 counties in three midwestern states. Users connect directly through the Internet, through regional Free-Nets, and by visiting one of 43 public access sites where networked workstations have been installed. The continued success of the project depends on developing partnerships, providing quality content and maintaining fair access.

Community-Institutional Relations↗
PubMed1979

Comparison of holdings of NLM (CATLINE) with those of resource libraries.

The collection development practices of the National Library of Medicine (NLM), with the goal of comprehensive acquisition of biomedical monographs, are compared with those of the resource libraries of the TALON (Region IX) Regional Medical Library. Holdings of two resource libraries in the TALON region, The University of Texas Health Science Center at San Antonio and The University of Texas Medical Branch at Galveston, and of the TALON Union Catalog of Monographs were compared with the NLM CATLINE data base for four subject classes and selected imprint years. Foreign-language coverage is lacking in Region IX, with English-language coverage is lacking in Region IX, with English-language coverage ranging between 70 and 88% of titles listed in CATLINE. Absent English-language material tends to be ephemeral or otherwise out of scope for the resource libraries. Between 7.1 and 18.8% of monographs acquired in each subject class by the two recource libraries are lacking in CATLINE; this represents between 2 and 8% of the CATLINE titles for each class.

Book Collecting↗
PubMed2005

Laboratory coherent-scatter analysis of intact urinary stones with crystalline composition: a tomographic approach.

Knowledge of urinary stone composition and structure provides important insights in guiding treatment and preventing recurrence. No current method can successfully provide information relating structure and composition of intact stones. We are developing a tomographic technique that uses measures of coherently scattered diagnostic x-rays to yield stone composition. Coherent-scatter (CS) properties depend on molecular structure and are, therefore, sensitive to material composition. Powdered, amorphous or polycrystalline materials with no significant orientation produce circularly symmetric CS patterns. However, in materials with preferred crystallite orientation, like urinary stones, bright spots in CS patterns are observed. This compromises a composition analysis based on comparing CS measurements from calculi to a library of CS signatures from powdered chemicals. We show that a computed tomographic reconstruction of CS measurements using filtered backprojection (CSCT) effectively eliminates bright spots and yields CS patterns equivalent to powdered materials. This allows for direct comparison with a powdered chemical reference library to establish composition. Validation is achieved through a tomographic CS analysis of an aluminium (Al) rod phantom. Much like calculi, CS patterns from a solid polycrystalline Al rod exhibit diffraction spots, absent in the ring-like Al powder CS pattern. We show that the reconstructed Al CS cross-section is equivalent to its powdered counterpart and results in clearly defined composition images. The potential of CSCT to identify stone composition is demonstrated through images of intact stones deemed chemically pure by infrared spectroscopy. Computed tomographic reconstruction of CS signals allowed the generation of composition maps, showing the distribution of stone components. These images provide strong evidence that current laboratory techniques risk missing critical stone components due to inadequate sampling. This is of particular importance since follow-up treatments are based on these composition analyses. CS analysis can distinguish common stone components and can provide topographic composition maps of intact stones. Such details offer invaluable clinical information regarding stone formation, treatment and follow-up, and thus support the development of CS analysis as a laboratory stone analysis technique.

Calcium↗
PubMed1995

Construction and utility of a human chromosome 22-specific Fosmid library.

We have previously demonstrated the capability of the Fosmid vector based on Escherichia coli F-factor replicon to stably propagate cosmid-sized human genomic DNA fragments. Using the Fosmid vector, we have constructed and arrayed a 10 x human chromosome 22-specific library, partly by picking human positive clones from a total Fosmid library constructed using DNA from human-hamster hybrid cell line containing human chromosome 22, and partly by using flow-sorted chromosomal DNA. The clones and physical contig maps of the clones in the library will serve as a valuable resource for detailed analysis of the chromosome by providing reliable materials for high resolution mapping and sequencing. In order to efficiently build physical maps for the chromosomal regions of interest spanning several hundred kilobases to a megabase, it is necessary to rapidly identify subsets of the Fosmid clones from the library that cover such regions. In this report, we describe a method of using random amplification products derived from YAC clones to rapidly identify a subset of Fosmid clones that cover a specific genomic subregion.

Animals↗
PubMed1985

DNA-mediated genetic transformation of mouse embryos and bone marrow--a review.

In recent years, new gene transfer systems have been developed which allow molecularly cloned genetic material to be introduced into whole organisms. These systems include the microinjection of DNA into mammalian embryos, transfection of DNA into mouse bone marrow cells, and the infection of early embryos with retroviruses. Exogenous DNA appears to integrate randomly into the host genome. The production of transgenic mice by injection of DNA into mouse embryos has rapidly gained importance as an experimental tool for the study of gene regulation during development. Through this technique, recombinant molecules of any type can be introduced into one-celled embryos, and thus can be used to study development from its earliest stages. DNA sequences have been shown to integrate and transmit through the germ line to subsequent generations as mendelian traits. Transgenic mice carrying various gene constructs have been successfully exploited for the elucidation of factors which determine tissue specificity of gene expression as well as the level of gene control. Phenotypic changes related to expression of foreign genes have also been observed. This experimental approach thus promises to rapidly solve many of the heretofore most challenging problems in developmental genetics. Insertion of foreign genes has also made possible the creation of insertional mutants which manifest themselves most frequently as recessives. Such mutations can be readily studied at the molecular level by using the transferred material as a probe for recovery of the affected host sequence from genomic libraries. Many of these same problems have been addressed by introducing retroviral DNA into mouse embryos. Here, the sequences used for transfer have been limited to retroviral genes, but nonetheless these experiments have been profitably exploited for studies both of gene regulation and mutagenesis. Gene transfer systems are being developed allowing the experimenter to transfer DNA into bone marrow cells of mice, after which the recipient cells can be reintroduced into lethally irradiated histocompatible animals. This system has the advantage that selection can be applied during the gene transfer process such that the expression of the foreign material is assured. In addition, these experiments have created a model system for production of animals carrying a subpopulation of cells which is highly resistant to a toxic agent. This system has the potential for therapeutic application to man.

Animals↗
PubMed2004

Design of highly specific ligands of fibrin for therapeutic applications.

The work presented here is aimed at designing high-affinity ligands for the fibrin gamma (312-324) epitope. This epitope is specific for fibrin recognition, as it is exposed only on the fibrin surface, while in fibrinogen it is buried in the protein bulk. This property makes it very useful for therapeutic applications. In fact, it may be exploited in driving systems for targeted delivery of thrombolytic drugs toward the specific compartment where they are needed. It will then allow avoidance of serious unwanted side effects produced by a conventional systemic administration. The approach chosen for designing putative ligands is based on the known three-dimensional (3D) structure of the epitope. A wide virtual library made up of oligo-peptides and analogues designed by a combinatorial approach, on the basis of chemical complementarity criteria, has been screened by means of a docking/scoring approach (DOCK program). The peculiarity of the problem under study required a considerable effort in finding a method enabling the experimental validation of the design work results. In fact the selected biological target is absolutely new, so that neither a endogenous, nor a synthetic high-affinity ligand is known up to now. It does not allow for the validation of computational results by means of classical binding tests based on the use of known labeled high-affinity ligands. Preliminary binding essayes were so carried out by means of the Plasmon Surface Resonance (PSR) technique. The experimental results suggested that most of the molecules predicted to be good ligands by means of the selected computational tools, could carry the wanted affinity toward the selected target.

Amino Acid Sequence↗
PubMed1979

The development and evaluation of a small ready-reference library collection for a rural practice: a case study.

A demonstration core collection of twenty-four ready-reference sources and five journals was selected cooperatively by a solo practitioner in rural Menifee County, Kentucky, and the University of Kentucky Medical Center Library Field Librarian to fit the ready-reference and current awareness information needs of a primary care solo rural practice in eastern Kentucky. The collection selections were systematically assessed by the physician to determine their utility in filling the practitioner's information needs with regard to his particular situation in terms of medical experience and level of training, available library and educational resources, and the type of health problems seen in his practice. This assessment showed that the Rural Demonstration Library Collection completely filled the information needs of the physician 66% of the time materials were consulted and filled his immediate information needs either completely or partially 82% of the time the collection was searched. This demonstration has shown that, under a specific set of circumstances, a librarian and a solo rural practitioner can effectively work together in identifying health sciences materials which fit the information needs of a solo rural practitioner. It suggests that cooperation between a librarian and a physician is important in meeting information needs.

Book Collecting↗
PubMedDate not supplied

An efficient and regiospecific strategy to N7-substituted purines and its application to a library of trisubstituted purines.

A regiospecific strategy for the preparation of N(7)-substituted purines in an efficient manner was devised. This approach to 6,7,8-trisubstituted purines relies on the cyclization reactions of suitably substituted pyrimidines (1) with either a carboxylic acid or an aldehyde. The method development for the five-step synthetic strategy outlined here was completed using 5-amino-4,6-dichloropyrimidine (4) as the starting material. The utility of this methodology was demonstrated through the preparation of a 40-membered library of 6,7,8-trisubstituted purines (3) in good yields and high purity.

Catalysis↗
PubMed2006

Elements of the granular gland peptidome and transcriptome persist in air-dried skin of the South American orange-legged leaf frog, Phyllomedusa hypocondrialis.

The defensive strategy of amphibians against predator attack relies heavily on the secretion of noxious/toxic chemical cocktails from specialized skin granular glands. Bioactive peptides constitute a major component of secretions in many species and the most complex are produced by neotropical leaf frogs of the sub-family Phyllomedusinae. We recently reported that these skin secretions contain elements of both the granular gland peptidome and transcriptome and that polyadenylated mRNAs constituting the latter are protected from degradation by interactions with endogenous amphipathic peptides. This thus permits parallel amino acid sequencing of peptides and nucleic acid sequencing of cloned precursor transcripts from single lyophilized samples of secretion. Here we report that the protection afforded is sufficiently robust to permit transcriptome studies by cloning of full-length polyadenylated peptide precursor encoding mRNAs from libraries constructed using ambient temperature air-dried skin from recently deceased specimens as source material. The technique was sufficiently sensitive to permit the identification of cDNAs encoding antimicrobial peptides constituted by six different isoforms of phylloseptin and two dermaseptins. Also, for the first time, establishment of the nucleic acid and amino acid sequence of the precursor encoding the phyllomedusine frog skin bradykinin-related peptide, phyllokinin, from cloned cDNA, was achieved. These data unequivocally demonstrate that the granular gland transcriptome persists in air-dried amphibian skin--a finding that may have fundamental implications in the study of archived materials but also in the wider field of molecular biology.

Amino Acid Sequence↗
PubMed2006

On two-parameter models of photon cross sections: application to dual-energy CT imaging.

The goal of this study is to evaluate the theoretically achievable accuracy in estimating photon cross sections at low energies (20-1000 keV) from idealized dual-energy x-ray computed tomography (CT) images. Cross-section estimation from dual-energy measurements requires a model that can accurately represent photon cross sections of any biological material as a function of energy by specifying only two characteristic parameters of the underlying material, e.g., effective atomic number and density. This paper evaluates the accuracy of two commonly used two-parameter cross-section models for postprocessing idealized measurements derived from dual-energy CT images. The parametric fit model (PFM) accounts for electron-binding effects and photoelectric absorption by power functions in atomic number and energy and scattering by the Klein-Nishina cross section. The basis-vector model (BVM) assumes that attenuation coefficients of any biological substance can be approximated by a linear combination of mass attenuation coefficients of two dissimilar basis substances. Both PFM and BVM were fit to a modern cross-section library for a range of elements and mixtures representative of naturally occurring biological materials (Z = 2-20). The PFM model, in conjunction with the effective atomic number approximation, yields estimated the total linear cross-section estimates with mean absolute and maximum error ranges of 0.6%-2.2% and 1%-6%, respectively. The corresponding error ranges for BVM estimates were 0.02%-0.15% and 0.1%-0.5%. However, for photoelectric absorption frequency, the PFM absolute mean and maximum errors were 10.8%-22.4% and 29%-50%, compared with corresponding BVM errors of 0.4%-11.3% and 0.5%-17.0%, respectively. Both models were found to exhibit similar sensitivities to image-intensity measurement uncertainties. Of the two models, BVM is the most promising approach for realizing dual-energy CT cross-section measurement.

Absorptiometry, Photon↗
PubMed1996

Library services for people with disabilities: results of a survey.

The Americans with Disabilities Act (ADA), enacted in 1990, has had a significant impact on the way many institutions, including libraries, do business. The Association of Research Libraries surveyed its members in 1991 to determine the effect of this legislation, and the author conducted a similar survey in 1995 to learn what progress academic health sciences libraries have made in serving the needs of people with disablities. A questionnaire was mailed to 131 members of the Association of Academic Health Sciences Library Directors. Nearly three-quarters of respondents reported elimination of physical barriers. The most common services provided are retrieval of materials from the stacks and photocopy assistance. Much less attention has been paid to the use of adaptive technology that allows disabled users to search a library's online catalog and databases; special technology is often provided by another unit on campus but there seems to be little coordination with library services Few libraries have assigned responsibility for disability services to a specific staff member and even fewer have done a formal assessment of the need for special services. The issues identified by the survey should challenge academic health sciences libraries to examine their status regarding compliance with ADA legislation.

Architectural Accessibility↗
PubMed2004

A "single-sample concept" (SSC): a new approach to the combinatorial chemistry of inorganic materials.

Combinatorial estimations show that, within an unreacted ceramic sample prepared by mixing N different starting materials MxOy with average particle size approximately 1 microm, there are about 10(12) grains per cubic centimeter, sufficient for local reactions to occur that may produce a larger number of product oxides than presently accessible by 2D plate techniques. The "single-sample concept" (SSC) is proposed for performing property-directed syntheses for the preparation of ferri-/ferromagnetic or superconducting compounds. Because of the magnetic properties of the products, libraries of product grains can be sorted by means of magnetic separation techniques. For materials with a large magnetization, the separation efficiency is so high that traces of products can be isolated. The SSC concept was tested experimentally to prepare Fe-based oxides (N=17, 24, 30). The large yields (<75 wt %, N=17) of product grains agree with the literature data, which indicate that 3d metal magnetic oxide phases (Tc>300 K) are most probably Fe oxides. In combination with magnetic separation techniques, SSC seems particularly adapted for exploring the solid-state chemistry of metallic lead elements that form ferri-/ferromagnetic or superconducting oxide phases difficult to detect systematically within the large phase space of theoretically existing compounds.

Journal Article↗
PubMed1993

MEDLINE Search Strategies for Literature on Asian Americans/Pacific Islanders.

PURPOSE OF THE REVIEW: The purpose of this study is to examine the professional health literature on Asian American/Pacific Islanders in MEDLINE, review the guiding indexing principles used in MEDLINE, and present suggestions on how to most effectively search for material in the database. SEARCH METHODS USED: The authors conducted database searches in MEDLINE and examined the National Library of Medicine indexing principles related to Asian Americans/Pacific Islanders to develop database search strategies. SUMMARY OF IMPORTANT FINDINGS: Two factors which contribute to the difficulty in identifying health literature on Asian Americans/Pacific Islanders are the small amount of material published when compared to other ethnic groups and the complex nature of indexing in MEDLINE that may create problems for less experienced database searchers. MAJOR CONCLUSIONS: Additional journal publications concerning Asian Americans/Pacific Islanders, a more thorough understanding of how the literature on this group is best retrieved from MEDLINE, and the development of more user&shy;friendly approaches to the National Library of Medicine databases will aid researchers interested in this ethnic group. KEY WORDS: Asian Americans, MEDLINE, periodicals, databases, bibliographic

Journal Article↗
PubMed2005

Postgraduate radiology training in sub-Saharan Africa: a review of current educational resources.

RATIONALE AND OBJECTIVE: Postgraduate training programs in radiology exist in several African nations. The ability of these programs to train radiologists is necessarily affected by local availability of educational resources, including clinical case volume, radiology equipment and maintenance, number of teaching faculty, and library and computer facilities. We sought to determine the current resources of a sample of African radiology education programs. MATERIALS AND METHODS: Site visits were conducted at three separate radiology training programs, one in Ghana and two in South Africa. At each site, the investigator conducted a technology census, assessed library resources, observed daily trainee activities, and interviewed trainees, faculty, and statisticians. RESULTS: African radiology trainees receive considerable training in fluoroscopy, ultrasound, and plain film radiography, but receive considerably less training in nuclear medicine, mammography, magnetic resonance imaging, and interventional radiology. A large amount of equipment in African teaching hospitals is inoperative because of lack of maintenance programs. Faculty to resident ratios in African teaching hospitals are much lower than in American hospitals. Needs of training programs vary greatly from hospital to hospital, and from country to country. CONCLUSION: Radiologists, radiology organizations, and radiology vendors from high-income nations are in a unique position to help Africa's postgraduate radiology training programs fulfill their mission of training Africa's next generation of radiologists. It is desirable that long-term commitments be made to teaching hospitals so that scarce donated resources may be put to the best possible use.

Africa South of the Sahara↗