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PubMed1991

Mechanism of electrographic seizure generation in the rat brain slice in low magnesium medium: modulatory effect of interictal bursting on seizure generation.

In order to understand the mechanisms underlying seizure generation, the present study investigated the functional and anatomical interaction between seizures and interictal bursts. Bathing rat brain slices of the hippocampus and entorhinal cortex in zero magnesium medium elicited electrographic seizures. In the later period, the electrographic seizures were eventually replaced by the interictal bursts. In this phase, lowering [K+]o and raising [Ca2+]o restored the tonic seizures by suppressing the interictal bursts. A multiple knife cut experiment revealed that the seizures arose in the entorhinal cortex and the interictal bursts originated in CA3. A selective knife cut across the subiculum showed that the interictal bursts, propagating from CA3 to the entorhinal cortex, disrupted and suppressed the electrographic seizures in standard Mg(2+)-free medium.

Animals↗

PubMed1972

The generation from arachidonic acid of rabbit aorta contracting substance (RCS) by a microsomal enzyme preparation which also generates prostaglandins.

1. Sodium arachidonate was incubated with a crude prostaglandin synthetase preparation made from dog spleen. The incubation was made in a dynamic system so that the products could be delivered to strips of rabbit aorta and rat stomach.2. A rabbit aorta contracting substance (RCS) and a prostaglandin-like substance were formed. The RCS had similar properties to that released in anaphylaxis. It was unstable and as the RCS activity declined, so the prostaglandin-like activity increased. Its formation was prevented by prostaglandin synthetase inhibitors such as indomethacin.3. A different rabbit aorta contracting substance was formed by incubation of arachidonate with lipoxygenase, which generates peroxides. This substance was stable and did not lead to prostaglandin production.4. We conclude that RCS may be an intermediate in prostaglandin production, such as the postulated cyclic endoperoxide.

Animals↗

PubMed2004

The significance of third-generation HCV RIBA-indeterminate, RNA-negative results in voluntary blood donors screened with sequential third-generation immunoassays.

BACKGROUND: One of the problems associated with the use of anti-HCV immunoblot assays is the interpretation of indeterminate results without detectable HCV RNA. The purpose of this study was to examine the significance of third-generation RIBA (RIBA-3)-indeterminate, RNA-negative results in voluntary blood donors. STUDY DESIGN AND METHODS: Since June 2000 all Australian Red Cross Blood Service testing sites have used an anti-HCV sequential immunoassay testing strategy whereby donors who are reactive on the primary screening immunoassay are tested on a secondary immunoassay and if reactive on both assays, further tested by immunoblot. From the four testing sites that use RIBA-3, the result profiles of donors who were RIBA-3-indeterminate, HCV RNA-negative were analyzed. RESULTS: From 2,661,786 donations screened for anti-HCV during the study period, 102 RIBA-3-indeterminate, RNA-negative donors were identified, most of whom were reactive to either c33p (69.6%) or c22p (27.5%). The RIBA-3-indeterminate, RNA-negative donors showed a significantly higher screening immunoassay signal strength to assay cutoff (S/CO) distribution than those with biologic false-reactive (BFR) results (1.853 vs. 1.524, p < 0.05) but a significantly lower distribution than RIBA-3-positive, RNA-negative (1.853 vs. 4.546, p < 0.05) or RNA-positive (1.853 vs. 6.467, p < 0.05) donors. The RIBA-3-indeterminate, RNA-negative donors showed a similar distribution of c33c and c22p band intensities compared with RIBA-3-positive, RNA-negative donors but significantly lower distribution of band strengths compared to the RIBA-3-positive, RNA-positive group. Compared to the indeterminate donors with previous anti-HCV-negative or BFR results, the indeterminate donors not previously screened for anti-HCV showed higher immunoassay S/CO ratio distributions, a higher proportion with c22p reactivity (16.2% vs. 36.7%), and higher frequency of risk factors (46.4% vs. 75.0%). CONCLUSIONS: Our analysis suggests that a combination of indicators can be used to help clarify RIBA-3-indeterminate, RNA-negative results. Specifically, donors with high S/CO ratios on a screening immunoassay, RIBA-3 reactivity to c22p or c33c with band intensity of 2+ or greater, without a previous history of negative or BFR donations and with an identifiable risk factor, have a high probability of representing true anti-HCV rather than nonspecific reactivity.

Blood Banking↗

PubMed2006

Complex minisatellite rearrangements generated in the total or partial absence of Rad27/hFEN1 activity occur in a single generation and are Rad51 and Rad52 dependent.

Genomes contain tandem repeat blocks that are at risk of expansion or contraction. The mechanisms of destabilization of the human minisatellite CEB1 (arrays of 36- to 43-bp repeats) were investigated in a previously developed model system, in which CEB1-0.6 (14 repeats) and CEB1-1.8 (42 repeats) alleles were inserted into the genome of Saccharomyces cerevisiae. As in human cells, CEB1 is stable in mitotically growing yeast cells but is frequently rearranged in the absence of the Rad27/hFEN1 protein involved in Okazaki fragments maturation. To gain insight into this mode of destabilization, the CEB1-1.8 and CEB1-0.6 human alleles and 47 rearrangements derived from a CEB1-1.8 progenitor in rad27Delta cells were sequenced. A high degree of polymorphism of CEB1 internal repeats was observed, attesting to a large variety of homology-driven rearrangements. Simple deletion, double deletion, and highly complex events were observed. Pedigree analysis showed that all rearrangements, even the most complex, occurred in a single generation and were inherited equally by mother and daughter cells. Finally, the rearrangement frequency was found to increase with array size, and partial complementation of the rad27Delta mutation by hFEN1 demonstrated that the production of novel CEB1 alleles is Rad52 and Rad51 dependent. Instability can be explained by an accumulation of unresolved flap structures during replication, leading to the formation of recombinogenic lesions and faulty repair, best understood by homology-dependent synthesis-strand displacement and annealing.

Alleles↗

PubMedDate not supplied

Comparison of first-generation and second-generation blood glucose meters for use in a hospital setting.

This study evaluated and compared a first- and a second-generation blood glucose meter for precision, accuracy, and user preference. Two separate capillary blood glucose fingersticks were performed on 25 outpatients and 60 inpatients with diabetes. Samples were drawn for serum glucose determinations immediately following the capillary fingersticks. Comparison of the Accu-Chek II and Satellite G meters in the outpatient setting gave results similar to the reference laboratory's. When the meters were tested on inpatients, the blood glucose results were significantly higher than those obtained from the hospital laboratory. The Accu-Chek II was more precise than the Satellite G on both normal and high blood glucose samples. Nursing staff indicated preference for the Satellite G because of its quick testing time but not for other preference factors surveyed. Both meters provided more accurate assessments of blood glucose concentration than were obtained from the serum glucose samples routinely processed by our hospital laboratory. Use of a nonfluorinated tube and delayed separation of the sample with resultant glycolysis likely account for this difference.

Blood Glucose↗

PubMed2004

Generations Exercising Together to Improve Fitness (GET FIT): a pilot study designed to increase physical activity and improve health-related fitness in three generations of women.

A 6-month home-based (HB) physical activity program was compared to a control (CTL) condition in terms of effect on physical activity and health-related fitness in three generations of women (daughter/ mother/maternal grandmother). Volunteers were randomly assigned to a HB or CTL condition. HB participants (n = 28) were asked to participate in lifestyle, aerobic, muscular strength, and flexibility activities at least 3 times per week and they completed 73% of the recommended PA bouts. CTL condition participants (n = 9) were asked to continue their usual pattern of physical activity. Changes in physical activity were measured pre-and post-intervention using the Physical Best questionnaire and pedometer step counts (3-day average). Changes in health-related fitness were assessed using Fitnessgram tests. Group x Time interactions were significant for changes in participation in flexibility activity (d/wk) and steps/day, indicating that the HB group experienced significant positive changes in the expected direction (+305% and +37%, respectively), while the CTL group regressed (-15% and -13%, respectively). The G x T interaction for mile time was significant, although not in the expected direction (CTL group < by 14% and HB group < by 5%). Findings should be interpreted with caution due to several limitations of the study, but several suggestions are made for more effectively studying this topic in the future.

Adolescent↗

PubMed2004

Highly coherent light at 13 nm generated by use of quasi-phase-matched high-harmonic generation.

By measuring the fringe visibility in a Young's double pinhole experiment, we demonstrate that quasi-phase-matched high-harmonic generation produces beams with very high spatial coherence at wavelengths around 13 nm. To our knowledge these are the highest spatial coherence values ever measured at such short wavelengths from any source without spatial filtering. This results in a practical, small-scale, coherent, extreme-ultraviolet source that is useful for applications in metrology, imaging, and microscopy.

Journal Article↗

PubMed2005

Simultaneous four-photon luminescence, third-harmonic generation, and second-harmonic generation microscopy of GaN.

We demonstrate what is to our knowledge the first example of four-photon luminescence microscopy in GaN and apply it to quality mapping of bulk GaN. The simultaneously acquired second- and third-harmonic generation can be used to map the distribution of the piezoelectric field and the band-tail state density, respectively. Through spectrum- and power-dependent studies, the fourth power dependence of the band edge luminescence is confirmed. The superb spatial resolution of the four-photon luminescence modality is also demonstrated. This technique provides a high-resolution, noninvasive monitoring and tool for examining the physical properties of semiconductors.

Journal Article↗

PubMed2006

Generation of high-energy self-phase-stabilized pulses by difference-frequency generation followed by optical parametric amplification.

We produce ultrabroadband self-phase-stabilized near-IR pulses by a novel approach where a seed pulse, obtained by difference-frequency generation of a hollow-fiber broadened supercontinuum, is amplified by a two-stage optical parametric amplifier. Energies up to 20 microJ with a pulse spectrum extending from 1.2 to 1.6 microm are demonstrated, and a route for substantial energy scaling is indicated.

Journal Article↗

PubMed2007

Third-harmonic generation in disguise of second-harmonic generation revisited: role of thin-film thickness and carrier-envelope phase.

It has previously been reported that a peak at the spectral position of the second harmonic of an excitation laser can be generated in an inversion-symmetric medium in the regime of extreme nonlinear optics and that this peak may be exploited to measure the carrier-envelope phase of the excitation pulse. Here we revisit this phenomenon with regard to reverse engineering the carrier-envelope phase and demonstrate that the thin-film thickness and the incident field can have a drastic influence on pulse propagation, and so the reverse engineering would likely fail.

Journal Article↗

PubMed1992

Generations and the generation of theory in social gerontology.

The process of theorizing, creating theoretical explanations, and disseminating theoretical perspectives is most frequently discussed in terms of disembodied ideas. A more insightful rendering of how theory is used in the sociology of aging literature would attend to the real individuals who promulgate the ideas. Looking at theorizing as a career-related activity engaged in by scholars who are prone to the same demographic imperatives as other human beings is a way of shedding more light on the many uses of theory. The concept of theoretical generations is utilized as a means of accounting for the succession of models and explanatory frameworks.

Aged↗

PubMedDate not supplied

The problems of generations: and generational analysis.

The focus of this paper is two fold: 1. conceptual and methodological problems underlying the life-span sociology literature that heretofore have not been discussed; and 2. application of the generational analysis model to the question of life cycle change in personal values. Specifically, we address the issues of whether (1) value change over the life course is a result of period shifts or individual maturation and (2) differences in values among age strata are a function of cohort experience or individual maturation (aging). Utilizing data from the Detroit Area Studies, four measures of values were constructed. The analyses shows that on only one of the four dependent measures was aging directly implicated in the findings. However, cohort differences and period effects were found to have a significant effect on the distribution of several of the value indices. The data are consistent with Mannheim's observation that older cohorts are affected by social change although the relative degree of observed change is much greater among the young.

Age Factors↗

PubMed2000

Skin test development in leprosy: progress with first-generation skin test antigens, and an approach to the second generation.

One of the most urgent needs from leprosy research is a test for infection. The lepromin test is not suitable as a diagnostic test for leprosy, and neither the Rees nor the Convit soluble antigens has appeared sufficiently specific. Because two new antigens, MLSA-LAM and MLCwA, may not fully meet the requirements for specificity, we have embarked upon the preparation of a second generation of skin test antigens. Size-fractionated cryptozoic proteins were prepared from M. leprae by electroelution from preoperative sodium dodecylsulphate-polyacrylamide gel electrophoresis, and individual fractions were probed with polyclonal and monoclonal antibody reagents to identify both known and novel proteins. In addition, immunological responses were assessed in M. leprae-sensitized guinea pigs against both crude subcellular fractions (cytosol, membrane, and soluble cell wall proteins) and the size-fractionated cytosolic proteins. A particularly promising subcellular fraction is the membrane fraction of M. leprae, which contains many proteins unique to the organism. Clinical trials of the M. leprae membrane proteins are now being planned.

Antigens, Bacterial↗

PubMed1999

Efficient computational algorithms for docking and for generating and matching a library of functional epitopes II. Computer vision-based techniques for the generation and utilization of functional epitopes.

This is the second review in a two-part series. In the first review (1) we described the computational complexity involved in the docking of a ligand onto a receptor surface. In particular, we focused on efficient algorithms designed to handle this computational task. Such a procedure results in a large number of potential, geometrically feasible solutions. The difficulty is to pinpoint which of these is the more likely candidate. While there exists a number of approaches to rank these solutions according to different criteria, such as the size of the interface or some approximation of their binding energetics, none of the existing methods has been shown to be consistently successful in this endeavor. If the binding site is unknown a priori, the magnitude of the task is awesome. Here we propose one way of addressing this problem, i.e., via derivation and utilization of binding epitopes. If a library of such epitopes is available, particularly for a large number of protein families, it may be used to predict more likely binding sites for a given ligand. We describe an efficient, computer-vision based method to construct binding epitopes focusing on two ways through which such a library can be generated, (i) molecular surface-based, or (ii) residue-based. Alternatively, the two can be combined. We further describe how such a library may be used efficiently in the matching/docking procedure.

Algorithms↗

PubMed1992

Spuriously low concentrations of serum iron measured with generation 14 Kodak Ektachem slides: prevalence, possible causes, and partial improvement with generation 16 slides.

For sera with iron (Fe) concentrations < 4 mumol/L, Kodak Ektachem slides Generation (GEN) 14 (without ascorbic acid) yielded systematically lower results for Fe than did liquid Ferrozine-based reagents from Baker containing ascorbic acid (10 g/L, final concentration) and adapted to Cobas-Bio. During an 8-month comparison period, outliers (defined as [Fe]Cobas - [Fe]Kodak > 4 mumol/L) were seen in 21 of the 8731 sera (0.24%) tested, corresponding to < 5% of the sera with [Fe]Kodak < 4 mumol/L. In vitro addition of ascorbic acid and (or) Fe identified at least two types of outliers: type 1 (approximately 70%), characterized by [Fe]Kodak > 0.4 mumol/L, by (supra)normal Fe recovery in Kodak slides in the presence or absence of ascorbic acid (10 g/L), and by between-method differences in serum Fe (Cobas - Kodak) that were significantly correlated with serum Zn content (P < 0.0004); and type 2 (approximately 30%), tentatively ascribed to contamination by EDTA, with serum Fe by Kodak < 0.4 mumol/L and Fe recovery near 0%, both of which could be significantly and dose-dependently increased by addition of ascorbic acid (5-20 g/L). For both types of outliers, flameless atomic absorption spectrometry (AAS) yielded results that were significantly higher than concentrations by Kodak with GEN 14. Use of GEN 16 slides (containing ascorbic acid) improved concordance of Kodak results with Cobas, and hence with flameless AAS, for both types of outliers; abolished Zn dependency of results; and increased Fe results in sera with type 2 outliers, although these remained substantially lower than by Cobas. However, like other ascorbic acid-containing reagents, GEN 16 slides were more sensitive to interference by dextran-bound Fe, as assessed during in vitro addition experiments and comparisons involving samples from Fe-dextran-treated patients. GEN 16 slides are hence expected to more frequently overestimate the physiologically available protein-bound Fe in hemodialysis patients. In hospital laboratories, this new interference will probably arise more frequently than the spuriously low results with GEN 14, hence warranting further efforts in optimizing Fe slides.

Ascorbic Acid↗

PubMed1992

Role of antigen-specific T cell help in the generation of in vivo antibody responses. I. Antigen-specific T cell help is required to generate a polyclonal IgG1 response in anti-IgD antibody-injected mice.

A system in which injection of mice with an antibody to mouse IgD that they recognize as foreign stimulates a large, T cell-dependent IgG response was used to study whether Ag-specific T cell help is required to stimulate polyclonal (non-Ag-specific) IgG production in vivo. Igha x Ighb allotype heterozygous mice were injected with a conjugate of a foreign Ag coupled to a mAb specific for one of the two IgD allotypes expressed in these mice. This conjugate cross-links mIgD on B cells that express the recognized allotype. These cells process the conjugate and present the foreign Ag to Ag-specific T lymphocytes, which become activated. Thus, B cells of the recognized allotype can be stimulated by cross-linking of their mIgD, Ag-specific T cell help, non-Ag-specific cytokines, and non-Ag-specific contact with activated T cells. In contrast, B cells that express the Igh allotype not recognized by the Ag-anti-IgD antibody conjugate (bystander B cells) can be stimulated in this system only by non-Ag-specific cytokines and non-Ag-specific contact with activated T cells. Although both recognized and bystander B cells in conjugate-injected mice demonstrated substantial increases in size and Ia expression, only the recognized B cells were induced to synthesize DNA and to make a substantial polyclonal Ig response. Bystander B cells still failed to secrete IgG when mice were injected with an anti-IgD-Ag conjugate specific for the other Igh allotype as well as a mAb that cross-linked IgD of the bystander B cell allotype. These observations demonstrate that although non-Ag-specific cytokine and contact-mediated T cell help are sufficient to induce B cells to increase in size and Ia expression in anti-IgD antibody-injected mice, Ag-specific T cell help is required to stimulate the generation of an IgG response in these mice.

Animals↗

PubMed2004

Characterization of the generation of radiolabeled monodisperse albuterol particles using the spinning-top aerosol generator.

UNLABELLED: Inhaled radiolabeled aerosols provide invaluable information about in vivo drug deposition. Here, we report our methodology for radiolabeling and imaging monodisperse pharmacologic aerosols in order to study basic aerosol science concepts of drug delivery within the human airways. METHODS: We used a spinning-top aerosol generator to produce (99m)Tc-labeled monodisperse albuterol sulfate aerosols of 1.5-, 3-, and 6- micro m mass median aerodynamic diameter. RESULTS: In vitro Andersen cascade validation data showed that technetium and albuterol were coassociated on each impactor stage for all 3 aerosols, and the radiolabeling process itself did not affect their particle size distributions. Good-quality gamma-camera scintigraphic images of lung and extrathoracic deposition were obtained within an asthmatic patient. CONCLUSION: We have successfully radiolabeled and imaged monodisperse albuterol aerosols within the human lungs. This novel technique provides an important tool to relate fundamental concepts of aerosol particle behavior, in vivo deposition, and therapeutic clinical response.

Administration, Inhalation↗

PubMed1979

Generation of virus specific cytotoxic T cells in vitro. III. Spleen cells stimulated by viral antigens generate alloreactive cytotoxic T cells.

Cytotoxic T lymphocytes (CTL) from DBA/2 strain mice primed with Sendai virus (SV) in vivo were activated by secondary stimulation of spleen cells with viral antigens in vitro and analyzed for their target antigen specificity. These effector cells lysed syngeneic Sendai virus infected target cells, marginally a variety of non-infected targets and had a strong cytotoxic effect on H-2b targets. Studies on the antigenic requirements revealed that all SV preparations which generated specific CTL also induced the alloreactive populations. Similar results were found in the response to Newcastle disease virus (NDV) and some influenza A viruses; all these viruses were mitogenic for lymphocytes. Experiments on the cellular requirements indicated that virus specific and alloreactive cells can be separated by their requirements for help and for restimulation. By competition experiments both activities could be attributed to clearly separable T cell subpopulations. The induction mechanism of alloreactive T cells by viral antigens is discussed.

Animals↗