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At least 253 records · Page 14Linked to original sources

Graphical comparisons of interferences in clinical chemistry instrumentation.

Instrument- and analyte-specific interferences can be produced by adding known concentrations of potentially interfering substances to serum from healthy volunteers. Analytical results are expressed as a percentage of the original (unaffected) result. Graphical displays of the transformed data document the conditions under which erroneous results would be probable for specimens containing the additive. If several analytical systems are available, one can make an informed choice of which to use for a particular analysis by comparing the appropriate graphical information. Comparisons of such displays of data from newer systems being considered for purchase may facilitate decisions regarding laboratory instrumentation.

Bilirubin↗

Barriers to the use of a diagnostic oral microbiology laboratory by general dental practitioners.

OBJECTIVE: To identify barriers on the use of diagnostic microbiology facilities in general dental practice. DESIGN: A cross-sectional survey using a postal questionnaire. SETTING: Primary/secondary care interface between the diagnostic oral microbiology laboratory, University of Glasgow Dental Hospital and School, Glasgow and dental practitioners within the surrounding health boards, 1998. SUBJECTS: All GDPs (797) within Argyll and Clyde, Ayrshire and Arran, Lanarkshire and Greater Glasgow Health Boards. MAIN OUTCOME MEASURES: The responses were expressed as both absolute and relative frequencies. RESULTS: Responses were received from 430 (55%). The most frequent reason for failure to use the service was lack of information, with more than half of the respondents claiming to be unaware of the facility. Lack of request forms and sampling equipment were also viewed as barriers to using the service. CONCLUSIONS: The laboratory is failing to successfully communicate its role in addressing the growing burden of antibiotic resistance in the community and must be more proactive in encouraging appropriate use and increasing accessibility of the service to GDPs.

Attitude of Health Personnel↗

Mouse LYVE-1 is an endocytic receptor for hyaluronan in lymphatic endothelium.

The glycosaminoglycan hyaluronan is a key substrate for cell migration in tissues during inflammation, wound healing, and neoplasia. Unlike other matrix components, hyaluronan (HA) is turned over rapidly, yet most degradation occurs not locally but within distant lymph nodes, through mechanisms that are not yet understood. While it is not clear which receptors are involved in binding and uptake of hyaluronan within the lymphatics, one likely candidate is the lymphatic endothelial hyaluronan receptor LYVE-1 recently described in our laboratory (Banerji, S., Ni, J., Wang, S., Clasper, S., Su, J., Tammi, R., Jones, M., and Jackson, D.G. (1999) J. Cell Biol. 144, 789-801). Here we present evidence that LYVE-1 is involved in the uptake of hyaluronan by lymphatic endothelial cells using a new murine LYVE-1 orthologue identified from the EST data base. We show that mouse LYVE-1 both binds and internalizes hyaluronan in transfected 293T fibroblasts in vitro and demonstrate using immunoelectron microscopy that it is distributed equally among the luminal and abluminal surfaces of lymphatic vessels in vivo. In addition, we show by means of specific antisera that expression of mouse LYVE-1 remains restricted to the lymphatics in homozygous knockout mice lacking a functional gene for CD44, the closest homologue of LYVE-1 and the only other Link superfamily HA receptor known to date. Together these results suggest a role for LYVE-1 in the transport of HA from tissue to lymph and imply that further novel hyaluronan receptors must exist that can compensate for the loss of CD44 function.

Amino Acid Sequence↗

A simple technique for obtaining high quality chromosome preparations from chorionic villus samples using FdU synchronization.

A fluorordeoxyuridine (FdU) synchronization technique was applied to 30 chorionic villus samples (CVS) from patients undergoing first trimester fetal diagnosis. The villi were incubated for 15 h in the presence of FdU. The block in DNA synthesis was subsequently released using thymidine and after an additional 5 h of incubation the mitotic cells were arrested in metaphases using a high concentration of colcemid. This method results in improved morphology of the chromosomes and a high mitotic index. A diagnostic chromosome analysis could be obtained in each clinical case using at least 15 well-spread metaphases. G-banded karyotypes were prepared of four metaphases in each case. The diagnostic procedure was completed within 48 h from the time of CVS. Use of this technique significantly improves the success rate of 'direct' chromosome analyses from CVS in a busy cytogenetic laboratory.

Chorionic Villi↗

Response and adaptation by plants to flooding stress.

Stress on plants imposed by flooding of the soil and deeper submergence constitutes one of the major abiotic constraints on growth, species' distribution and agricultural productivity. Flooding stress is also a strong driver of adaptive evolution. This has resulted in a wide range of biochemical, molecular and morphological adaptations that sanction growth and reproductive success under episodic or permanently flooded conditions that are highly damaging to the majority of plant species. However, even seemingly poorly adapted species possess some short-term resilience that is important for overall success of these plants in various habitats. The papers contained in this Special Issue address these topics and emphasize molecular, biochemical and developmental processes that impact on flooding tolerance. Most of the articles are based on lectures given to the 8th Conference of the International Society for Plant Anaerobiosis (ISPA), held at the University of Western Australia, Perth, 20-24 September, 2004. Reviews and research papers are presented from the leading laboratories currently working on plant responses to flooding stress.

Acclimatization↗

Evaluation of a technique for identification of Shiga-like toxin-producing Escherichia coli by using polymerase chain reaction and digoxigenin-labeled probes.

A polymerase chain reaction (PCR) technique for the identification of Shiga-like toxin (SLT)-producing Escherichia coli was assessed by using 95 strains of SLT-producing E. coli and 5 Shigella dysenteriae type 1 strains. PCR was used for the amplification of slt gene sequences from whole bacterial colonies. A digoxigenin-labeled DNA probe was used for identification of the PCR products in a spot blot hybridization assay. Modifications were made to adapt this technique for the proper identification of 10 SLT-producing isolates which were refractory to the heat lysis step that was used to liberate whole-cell DNA for PCR and 6 isolates which gave nonspecific amplification products. The sensitivity and specificity of this assay were each 99% when compared with toxin neutralization results by using SLT-specific monoclonal antibodies. These values indicate that this detection technique could be suitable for use in a clinical laboratory.

Antibodies, Monoclonal↗

Establishment of a quality assurance program for human immunodeficiency virus type 1 DNA polymerase chain reaction assays by the AIDS Clinical Trials Group. ACTG PCR Working Group, and the ACTG PCR Virology Laboratories.

An independent quality assurance program has been established by the Virology Committee of the AIDS Clinical Trials Group in the Division of AIDS, National Institute of Allergy and Infectious Diseases, for monitoring polymerase chain reaction (PCR) assays for human immunodeficiency virus type 1 (HIV-1) DNA that are performed by 11 laboratories participating in multicenter clinical trials in the United States. To perform HIV-1 DNA PCR for patients in AIDS Clinical Trials Group protocols, each laboratory was initially certified by correctly testing a coded certification panel consisting of eight well-defined clinical whole-blood specimens and 30 cell pellets containing 0, 2, 5, 10, 20, or 50 8E5/LAV cells per 125,000 uninfected peripheral blood mononuclear cells. PCR was performed by one of two standardized commercial assays for amplification and nonisotopic detection of HIV-1 proviral DNA. For continuing certification, each laboratory must correctly test eight coded whole-blood samples per quarter and run three or four coded cell pellets and HIV-1 DNA copy standards with every PCR assay in real time. The PCR results for the coded pellets on each run are entered into an encrypted computer file, which immediately assesses the validity of the run. To date, 10 of 11 laboratories have correctly tested all HIV-1-positive and -negative samples in the initial certification panel on their first or second attempt. Subsequently, 9 of these 11 laboratories have continued to maintain their certified status. The use of commercial HIV-1 DNA PCR assays and an external quality assurance program have ensured that results from different laboratories are comparable and that problems with sensitivity and specificity are quickly identified.

Certification↗

Cellular immune response to pulmonary infections in HIV-infected individuals hospitalized with diverse grades of immunosuppression.

The lymphocyte profile of 521 HIV-infected subjects hospitalized at Jackson Memorial (2001-2002) was compared across main respiratory diseases. Study data included medical history and all laboratory evaluations performed during hospitalization. Community-acquired pneumonias (CAP, 52%), Pneumocystis jiroveci pneumonia (PCP, 24%), tuberculosis (TB, 9%) and non-tuberculous mycobacterial diseases (NTM, 12%) were the most frequent causes of admission. Patients hospitalized with PCP and NTM exhibited the lowest CD4 counts (P=0.003). PCP patients had the highest B-cell percentages (P=0.04). CAP patients had the highest CD8 and CD4 percentages and the lowest percentage of Natural Killer (NK) cells and viral burdens. TB patients exhibited the lowest NK-cell (11.4+/-6.3) and B-cell percentages (13.6+/-12) and the highest CD8 (59+/-14) percentage. NTM patients, in contrast, had the highest NK-cell percentages of the groups (19.1+/-11.6, P=0.01). Additionally, immune responses associated with respiratory pathogens differed in HIV-infected patients with CD4(+) cells above and below 200 counts.

Adult↗

Chancroid detected by polymerase chain reaction--Jackson, Mississippi, 1994-1995.

Chancroid is a sexually transmitted disease (STD) caused by infection with Haemophilus ducreyi and is characterized by genital ulceration. Chancroid is underreported in the United States (1), reflecting, in part, difficulties in diagnosis because of clinical similarities between chancroid and other ulcerative STDs. In addition, laboratory confirmation by culture is 53%-84% sensitive and often is unavailable in clinical settings (2). In September 1994, clinicians at the District V STD clinic of the Mississippi State Department of Health (MSDH) in Jackson reported examining patients with genital ulcers characteristic of chancroid but lacked capacity to confirm the diagnosis. To determine the cause of the ulcers, MSDH, in conjunction with CDC, conducted an investigation of all patients with genital ulcers examined at the Jackson STD clinic during October 20, 1994-February 1, 1995. This report summarizes the findings of the investigation.

Adolescent↗

Characterization of LH-RH immunoreactivity in mammalian pituitary neural lobe by HPLC.

High performance liquid chromatography was used to characterize luteinizing hormone-releasing hormone (LH-RH) immunoreactivity that was previously identified immunocytochemically in the pituitary neural lobes of bats, ferrets and humans. Extracts of bat posterior lobe and hypothalamus, ferret posterior lobe and hypothalamus and human neurohypophysis were partially purified with C-18 Bond-Elut cartridges. Samples were chromatographed using a C-18 reverse phase HPLC column, and LH-RH-immunoreactive moieties were separated by gradient elution (TFA/acetonitrile solvent system). For bats and ferrets, the major peak of neural lobe LH-RH immunoreactivity eluted with a retention time identical to that of hypothalamic LH-RH. Synthetic mammalian standard added to bat and ferret hypothalamic extracts coeluted as a single peak with the predominant form of LH-RH immunoreactivity present in those tissues. In humans, the peak of LH-RH immunoreactivity in neural lobe extracts coeluted with synthetic standard. These results provide strong evidence that the LH-RH-immunoreactive fibers which terminate within the neural lobe contain authentic LH-RH. Additional minor peaks of LH-RH immunoreactivity were observed in posterior lobe and hypothalamic extracts of both bats and ferrets. Comparisons of posterior lobe content of LH-RH immunoreactivity across species verify that the neural lobe projection is a major component of the LH-RH system in bats, whereas it is represented only minimally in the laboratory rat.

Adult↗

Plasticity and tissue regenerative potential of bone marrow-derived cells.

Diverse in vivo studies have suggested that adult stem cells might have the ability to differentiate into cell types other than those of the tissues in which they reside or derive during embryonic development. This idea of stem cell "plasticity" has led investigators to hypothesize that, similar to embryonic stem cells, adult stem cells might have unlimited tissue regenerative potential in vivo, and therefore, broad and novel therapeutic applications. Since the beginning of these observations, our group has critically examined these exciting possibilities for mouse bone marrow-derived cells by taking advantage of well-characterized models of tissue regeneration, Cre/lox technology, and novel stem cell isolation protocols. Our experimental evidence does not support plasticity of hematopoietic stem cells as a frequent physiological event, but rather indicates that cell fusion could account for reported cases of hematopoietic stem cell plasticity or "transdifferentiation" in vivo. Our studies highlight the need for meticulous technical controls during the isolation, transplantation, tracking, and analysis of bone marrow-derived cells during in vivo studies on plasticity. Further studies will be necessary to better define experimental conditions and criteria to unequivocally prove or reject plasticity in vivo. In this review, we focus on results from several studies from our laboratory, and discuss their conclusions and implications.

Animals↗

Probing expert anticipation with the temporal occlusion paradigm: experimental investigations of some methodological issues.

Two experiments were conducted to examine whether the conclusions drawn regarding the timing of anticipatory information pick-up from temporal occlusion studies are influenced by whether (a) the viewing period is of variable or fixed duration and (b) the task is a laboratory-based one with simple responses or a natural one requiring a coupled, interceptive movement response. Skilled and novice tennis players either made pencil-and-paper predictions of service direction (Experiment 1) or attempted to hit return strokes (Experiment 2) to tennis serves while their vision was temporally occluded in either a traditional progressive mode (where more information was revealed in each subsequent occlusion condition) or a moving window mode (where the visual display was only available for a fixed duration with this window shifted to different phases of the service action). Conclusions regarding the timing of information pick-up were generally consistent across display mode and across task setting lending support to the veracity and generalisability of findings regarding perceptual expertise in existing laboratory-based progressive temporal occlusion studies.

Adult↗