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At least 271 records · Page 15Linked to original sources
PubMed2003

The detection of t(14;18) in archival lymph nodes: development of a fluorescence in situ hybridization (FISH)-based method and evaluation by comparison with polymerase chain reaction.

Fluorescence in situ hybridization (FISH) has been used to demonstrate the t(14;18) in up to 100% of follicular lymphoma (FL) cases, however, there is little reproducible data using fixed tissue. The aim was therefore to develop a robust FISH method for the demonstration of translocations in archival tissue. The technique was evaluated by comparison with multiplex polymerase chain reaction (PCR), capable of detecting the majority of known breakpoints. Twenty-eight paired frozen and fixed cases of FL and 20 reactive controls were analyzed. The t(14;18) was detected in 23 of 28 cases using PCR on frozen material and 8 of 20 in paraffin. Using FISH, 24 of 26 frozen and 26 of 28 paraffin cases had a demonstrable translocation. All 20 reactive nodes were negative for the t(14;18) by PCR. Using FISH, one of the reactive cases had occasional cells with a translocation FISH pattern, demonstrable in frozen and paraffin samples. This is consistent with the presence of the t(14;18), which is well described in normal individuals. Both PCR and FISH are highly effective for t(14;18) analysis in unfixed tissue. When only paraffin blocks are available, FISH is the method of choice, and a result was achieved in 100% of cases. The method is applicable to the retrospective analysis of a range of translocations.

Chromosomes, Human, Pair 14↗
PubMed1993

Kraepelin revisited: a reassessment and statistical analysis of dementia praecox and manic-depressive insanity in 1908.

A meta-analysis was carried out on 53 cases of dementia praecox (DP) and 134 cases of manic-depressive insanity (MDI) originally diagnosed by Kraepelin or his collaborators in Munich in 1908. The original case material was coded in terms of Present State Examination syndromes and analysed statistically for internal consistency and discrimination between the two diagnostic entities. Kraepelin's DP and MDI were found to define homogeneous groups of disorders which could be clearly distinguished from one another. A CATEGO re-classification of the cases revealed an 80.2% concordance rate between Kraepelin's diagnoses and ICD-9. Cluster analysis of the original data reproduced closely Kraepelin's dichotomous classification of the psychoses but suggested that DP was a narrower concept than schizophrenia today, while MDI was a composite group including both 'typical' manic-depressive illnesses and schizoaffective disorders.

Adult↗
PubMed2001

Laser-induced multidimensional fluorescence spectroscopy in Shpol'skii matrixes with a fiber-optic probe at liquid helium temperature.

Improved methodology for chemical analysis via laser-excited Shpol'skii spectrometry at liquid helium temperature (4.2 K) is reported. Sample freezing is performed in a matter of seconds with the aid of a fiber-optic probe directly inserted into the liquid cryogen. Emission wavelength time matrixes, excitation emission wavelengths, and time-resolved excitation emission wavelengths are rapidly collected with the aid of a pulsed tunable dye laser, a high-resolution spectrograph, and an intensified charged-couple device. Data reproducibility for qualitative and quantitative analysis purposes and analytical figures of merit are demonstrated for several polycilic aromatic hydrocarbons/n-alkane systems. Fluorescence lifetime differences from analyte molecules occupying different crystallographic sites in the same frozen matrix are presented for the first time. The potential of our approach is illustrated for the direct analysis of a benzopyrene fraction typically encountered in HPLC analysis of polycyclic aromatic hydrocarbons.

Journal Article↗
PubMed2002

Single-pass attenuated total reflection Fourier transform infrared spectroscopy for the analysis of proteins in H2O solution.

The application of single-pass attenuated total reflection Fourier transform infrared (ATR-FT-IR) microscopy was investigated for secondary structure analysis of 15 representative proteins in H2O solution. This is the first reported application of single-pass ATR-FT-IR for protein analysis; thus, the method was validated using transmission FT-IR and multipass ATR-FT-IR as referee methods. The single-pass ATR-FT-IR technique was advantageous since the single-pass geometry permits rapid secondary structure analysis on small volumes of protein in H2O solution without the use of demountable thin path length sample cells. Moreover, the fact that H2O backgrounds were small allowed the simultaneous observation of the amide I-III, A, and B regions without having to perform H2O subtraction. A comparison of replicate protein spectra indicated that the single-pass ATR-FT-IR method yields more reproducible data than those acquired by transmission FT-IR. The observed trends for the amide I-III and A bands obtained by single-pass ATR-FT-IR agreed with those in the literature for conventional transmission FT-IR.

Animals↗
PubMed2004

Discrimination of bacteria using surface-enhanced Raman spectroscopy.

Raman spectroscopy has recently been shown to be a potentially powerful whole-organism fingerprinting technique and is attracting interest within microbial systematics for the rapid identification of bacteria and fungi. However, while the Raman effect is so weak that only approximately 1 in 10(8) incident photons are Raman scattered (so that collection times are in the order of minutes), it can be greatly enhanced (by some 10(3)-10(6)-fold) if the molecules are attached to, or microscopically close to, a suitably roughened surface, a technique known as surface-enhanced Raman scattering (SERS). In this study, SERS, employing an aggregated silver colloid substrate, was used to analyze a collection of clinical bacterial isolates associated with urinary tract infections. While each spectrum took 10 s to collect, to acquire reproducible data, 50 spectra were collected making the spectral acquisition times per bacterium approximately 8 min. The multivariate statistical techniques of discriminant function analysis (DFA) and hierarchical cluster analysis (HCA) were applied in order to group these organisms based on their spectral fingerprints. The resultant ordination plots and dendrograms showed correct groupings for these organisms, including discrimination to strain level for a sample group of Escherichia coli, which was validated by projection of test spectra into DFA and HCA space. We believe this to be the first report showing bacterial discrimination using SERS.

Escherichia coli↗
PubMedDate not supplied

Chromosome instability in Spodoptera frugiperda Sf-9 cell line.

Homogeneous cell lines are essential in industry and research if reliable and reproducible data are to be obtained. The Spodoptera frugiperda (Sf-9) cell line routinely used for the production of recombinant proteins was found to be heterogeneous, containing a mixture of diploid and tetraploid cells. Using dilution-cloning techniques, diploid and tetraploid subpopulations were isolated from a Sf-9 parental cell line, and their cytogenetic state was monitored using Vinblastine to arrest cells in mitosis. Flow cytometry was used to obtain a snapshot of the predominant subpopulations present to verify the karyological results. The rate at which clonal populations digress into the heterogeneous state was found to be more rapid for the diploid subpopulation, with the emergence of tetraploid cells after only 11 passages, than for the tetraploid subpopulation, where diploid clones appeared after 18 passages. The chromosomes in both diploid and tetraploid subpopulations as well as the parental cell line were found to spontaneously fragment during growth and expansion processes, giving rise to variable chromosome numbers. DNA analysis of cell lines obtained from laboratories worldwide have shown that the Sf-9 cell line used for the production of many recombinant proteins is cytologically unstable, leading to varying degrees of polyploidal state depending on its culture history and supplier.

Animals↗
PubMed2004

Low inertia impact dynamics for nanodrops.

Simulations of a droplet impacting a flat solid surface with a small initial speed have been studied using molecular dynamics. Approximating the shape of the drop by a spheroid, spreading radii, and dynamic contact angles are measured. The data reproduce well experimental results from literature. We show that the difference between the equilibrium and the dynamic contact angle cosines, that is, the spontaneous driving force, versus the spreading velocity of the three-phase line varies with impact speed and consists of two distinct regimes which can be described by existing models of moving contact lines.

Journal Article↗
PubMed2005

The role of a clinical veterinarian in a safety assessment testing facility.

A clinical veterinarian working in a safety assessment testing facility must balance animal welfare concerns with the attainment of sound, reproducible data necessary for regulatory studies. Drawing on her experience as a clinical veterinarian with specialty training in the field of toxicology, and past experience as a Study Director on safety assessment studies, the author describes practices that facilitate the veterinarian's role to ensure animal welfare on safety assessment studies.

Animal Care Committees↗
PubMed1999

Quality assurance in measuring the elemental composition of the alga Fucus vesiculosus.

Algae are increasingly used for the purpose of environmental biomonitoring, for instance in the long-term program of the Federal Environmental Specimen Bank of Germany. Therefore, for the studies presented here, freeze-dried samples of Fucus vesiculosus collected from the North Sea shores were analyzed for a broad range of elements by instrumental neutron activation analysis (INAA), while inductively coupled plasma atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) were carried out on digests. The entire analytical procedures, including field sampling, cleaning of material, sample handling, determination of blanks and instrumental parameters, are described. Certified reference materials analyzed in parallel with real samples and intermethod comparisons were used for assuring the accuracy of the analytical data. Reproducibility of INAA measurements was between 4 and 6% depending on the element considered. Possible sources of uncertainty and variation of the contaminant origins are discussed. Boundary conditions for the performance of algae sampling within environmental monitoring programs and the application of this marine bioindicator for the purpose of controlling time-dependent and local differences in element patterns are presented.

Cryopreservation↗
PubMed2006

Gating current flowing through molecules in metal-molecules-metal junctions.

We have assembled two junctions that incorporate redox sites between Hg electrodes by different interactions. In the first junction, Hg-SAM-R//R-SAM-Hg, the redox site (R) are covalently linked to each electrode in self assembled monolayers (SAM-R). In the second junction, Hg-SAM//R//SAM-Hg, the redox sites dissolved in solution are trapped by electrostatic interaction at the SAM formed at the electrodes. The current flowing through these junctions can be controlled by adjusting the potential applied at the electrodes with respect to the redox potential of the species by using an electrochemical system. The current flowing in these two junctions is mediated by the redox sites through different mechanisms. In particular, the current flowing through the Hg-SAM-R//R-SAM-Hg junction occurs through a self exchange mechanism between the redox sites organized at each electrode, while the current flowing through the Hg-SAM//R//SAM-Hg junction is dominated by a redox-cycling mechanism. The systems described here are easy to assemble, well-characterized, yield reproducible data and make it easy to modify the electrical properties of the junctions by changing the nature of the redox centres. For these characteristics they are well suited for collecting fundamental information relevant to the fabrication of molecular switches.

Journal Article↗
PubMed2006

Surface-enhanced Raman scattering for the rapid discrimination of bacteria.

Raman spectroscopy is attracting interest for the rapid identification of bacteria and fungi and is now becoming accepted as a potentially powerful whole-organism fingerprinting technique. However, the Raman effect is so weak that collection times are lengthy, and this insensitivity means that bacteria must be cultured to gain enough biomass, which therefore limits its usefulness in clinical laboratories where high-throughput analyses are needed. The Raman effect can fortunately be greatly enhanced (by some 10(3)-10(6)-fold) if the molecules are attached to, or microscopically close to, a suitably roughened surface; a technique known as surface-enhanced Raman scattering (SERS). In this study we investigated SERS, employing an aggregated silver colloid substrate, for the analysis of a closely related group of bacteria belonging to the genus Bacillus. Each spectrum took only 20 s to collect and highly reproducible data were generated. The multivariate statistical technique of principal components-discriminant function analysis (PC-DFA) was used to group these bacteria based on their SERS fingerprints. The resultant ordination plots showed that the SERS spectra were highly discriminatory and gave accurate identification at the strain level. In addition, Bacillus species also undergo sporulation, and we demonstrate that SERS peaks that could be attributed to the dipicolinic acid biomarker, could be readily generated from Bacillus spores.

Bacillus↗
PubMed2000

Diagnosis of pemphigus by ELISA: a critical evaluation of two ELISAs for the detection of antibodies to the major pemphigus antigens, desmoglein 1 and 3.

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are characterized by autoantibodies to the desmosomal glycoproteins desmoglein 3 (Dsg 3) and Dsg 1 (Dsg 1), respectively. In this study, two enzyme-linked immunosorbent assays (ELISA) which detect IgG autoantibodies to Dsg 1 and Dsg 3 have been evaluated. A total of 317 normal and disease controls, 82 patients with PV and 25 with PF were studied. The Dsg 3 ELISA was positive in all 34 patients with untreated PV and the Dsg 1 ELISA was positive in all 10 with untreated PF. When patients undergoing treatment were included, the sensitivities fell to 95% and 92%, respectively, but still compared favourably to the sensitivity of indirect immunofluorescence which was 79% in PV and 84% in PF. All PF sera were negative in the Dsg 3 ELISA and the specificity of both assays was 98% or greater. Large numbers of samples could be analysed simultaneously over a relatively short time period. The Dsg 1 and Dsg 3 ELISAs also provided objective, quantitative, reproducible data which allowed differentiation of PV from PF and in view of these advantages, they are likely to become a routine technique in diagnostic laboratories.

Adolescent↗
PubMed2001

Reproducibility of exercise tolerance in patients with end-stage renal disease.

OBJECTIVE: To determine the interday reproducibility of peak and submaximal exercise tolerance of patients with end-stage renal disease (ESRD). DESIGN: Repeated measures. SETTING: Day-patient rehabilitation center. PARTICIPANTS: Twelve consecutively presenting, self-selected patients with ESRD. INTERVENTIONS: All patients performed peak exercise tolerance assessments on a cycle ergometer up to the point of volitional fatigue, with a 1-week interval between the 2 tests. MAIN OUTCOME MEASURES: Cardiopulmonary, hemodynamic, and physical performance parameters were assessed at peak exercise and at the lactate threshold. Standard error of measurement, percentage coefficient of variation (CV%), intraclass correlation coefficient (ICC), and limits of agreement (LOA) were calculated to determine the reproducibility of all variables. RESULTS: CV% (range, 5%-7%) and ICCs (range, .94 - .98) for oxygen uptake and heart rate at peak exercise and lactate threshold indicated highly acceptable levels of group mean reproducibility. LOA analysis revealed satisfactory levels of reproducibility for individual patients. CONCLUSION: Taken together, these reproducibility data may be applied to clinical work, requiring the quantification of changes in the exercise tolerance of patients with ESRD after short-term interventions (eg, exercise training, therapeutic use of recombinant erythropoietin).

Exercise Tolerance↗
PubMedDate not supplied

Surface tension of therapeutic surfactants (exosurf neonatal, infasurf, and survanta) as evaluated by standard methods and criteria.

Three commercial preparations for the treatment of neonatal respiratory distress syndrome (NRDS), Exosurf Neonatal (EX), Infasurf (IN), and Survanta (SU), were studied at 37 degrees C in both a pulsating bubble surfactometer and a vertical film surface balance. "Static" characteristics of adsorbed films were assessed with "bubble" at maximum radius (Rmax) and at minimum radius (Rmin). Adsorption time was time to stable film formation (gamma equilibrium). In dynamic experiments, the bubble was cycled (compressed-decompressed) between Rmax and Rmin at 20, 40, and 80 cpm. Spread films were cycled in the surface balance between maximum area (Amax) and minimum area (A(min)) at 1.5 cpm. In all experiments, maximum surface tension (gamma max) coincided with Rmax or Amax and gamma min with Rmin or A(min). All trials were continued until gamma max and gamma min were reproducible. Data were evaluated according to standard criteria for normal function both in vivo and in vitro of lipid mixtures (EX) or natural surfactants (IN, SU) prepared for treatment of NRDS. All preparations failed two of the four criteria, adsorption in the time of a deep breath and maintenance of stable, low gamma. Adsorption required 10 to 20 seconds and stable gamma was achieved only at equilibrium gamma, > 17 mN/m. IN and SU conformed in general to two criteria, gamma approaching zero on compression and low surface compressibility (< 0.09 m/mN), whereas spontaneously formed films of EX did not. EX was idiosyncratic in that these two criteria were met only after an apparent change of film conformation had been effected, possibly related to elimination of preparation additives from the surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Products↗
PubMed2004

FamClash: a method for ranking the activity of engineered enzymes.

This article introduces the computational procedure FamClash for analyzing incompatibilities in engineered protein hybrids by using protein family sequence data. All pairs of residue positions in the sequence alignment that conserve the property triplet of charge, volume, and hydrophobicity are first identified, and significant deviations are denoted as residue-residue clashes. This approach moves beyond earlier efforts aimed at solely classifying hybrids as functional or nonfunctional by correlating the rank ordering of these hybrids based on their activity levels. Experimental testing of this approach was performed in parallel to assess the predictive ability of FamClash. As a model system, single-crossover ITCHY (incremental truncation for the creation of hybrid enzymes) libraries were prepared from the Escherichia coli and Bacillus subtilis dihydrofolate reductases, and the activities of functional hybrids were determined. Comparisons of the predicted clash map as a function of crossover position revealed good agreement with activity data, reproducing the observed V shape and matching the location of a local peak in activity.

Bacillus subtilis↗
PubMed2005

Simulation of dynamical properties of normal and superfluid helium.

The formation of a superfluid when (4)He is cooled below the characteristic lambda transition temperature is accompanied by intricate quantum mechanical phenomena, including the emergence of a Bose condensate. A combination of path integral and semiclassical techniques is used to calculate the single-particle velocity autocorrelation function across the normal-to-superfluid transition. We find that the inclusion of particle exchange alters qualitatively the shape of the correlation function below the characteristic transition temperature but has no noticeable effect on the dynamics in the normal phase. The incoherent structure factor extracted from the velocity autocorrelation function is in very good agreement with neutron scattering data, reproducing the width, height, frequency shift, and asymmetry of the curves, as well as the observed increase in peak height characteristic of the superfluid phase. Our simulation demonstrates that the peak enhancement observed in the neutron scattering experiments below the transition temperature arises exclusively from particle exchange, illuminating the role of Bose-statistical effects on the dynamics of the quantum liquid.

Journal Article↗
PubMed2004

LC-UV and LC-MS analysis of food and drink products containing kava.

A method for the determination of six kava lactones, methysticin, dihydromethysticin, kawain, dihydrokawain, yangonin and desmethoxyyangonin, in solid foods and beverages has been developed. Solid samples were prepared using methanol extraction, while beverages were extracted using a separate solid phase extraction (SPE) method. After sample preparation, the extracts were analysed using LC-UV or atmospheric pressure photoionization (APPI) LC-MS in the positive mode. Using the method, 10 beverage products, two chocolate products, three unbrewed tea products, three dietary supplements and a drink mix product were analysed. The results obtained using the LC-UV were comparable to those obtained using APPI-LC-MS for most products. Using the SPE method in conjunction with LC-MS, individual kava lactones were detected in drink products at ppb concentrations. Concentrations of total kava lactones ranged between 135-0.035 mg per serving in the food and beverage products tested and between 40-61 mg per serving for the dietary supplement products tested. Results of these analyses as well as extraction efficiency and reproducibility data are reported.

Beverages↗
PubMed2003

Influence of high-frequency electromagnetic fields on different modes of cell death and gene expression.

PURPOSE: International thresholds for exposure to non-ionizing radiation leading to non-thermal effects were conservatively set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The aim of this study was to examine whether biological effects such as different modes of cell death and gene expression modifications related to tumorgenesis are detectable above the threshold defined. MATERIALS AND METHODS: Human leukaemia cells (HL-60) grown in vitro were exposed to electromagnetic fields (EMF; t 1/2(r) about 1 ns; field strength about 25 times higher than the ICNIRP reference levels for occupational exposure) leading to non-thermal effects using a high-voltage-improved GTEM cell 5302 (EMCO) connected to a pulse generator NP20 (C = 1 nF, U(Load) = 20kV). HL-60 cells were harvested at 0, 24, 48 and 72 h after radiation exposure. Micronuclei, apoptosis and abnormal cells (e.g. necrosis) were determined using morphological criteria. In parallel, the expression of 1176 genes was measured using Atlas Human 1.2. Array. Based on high data reproducibility calculated from two independent experiments (> 99%), array analysis was performed. RESULTS: No significant change in apoptosis, micronucleation, abnormal cells and differential gene expression was found. CONCLUSIONS: Exposure of HL-60 cells to EMFs 25 times higher than the ICNIRP reference levels for occupational exposure failed to induce any changes in apoptosis, micronucleation, abnormal morphologies and gene expression. Further experiments using EMFs above the conservatively defined reference level set by the ICNIRP may be desirable.

Apoptosis↗