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At least 163 records · Page 9Linked to original sources

PubMed1997

Glutamatergic N2v cells are central pattern generator interneurons of the lymnaea feeding system: new model for rhythm generation.

We aimed to show that the paired N2v (N2 ventral) plateauing cells of the buccal ganglia are important central pattern generator (CPG) interneurons of the Lymnaea feeding system. N2v plateauing is phase-locked to the rest of the CPG network in a slow oscillator (SO)-driven fictive feeding rhythm. The phase of the rhythm is reset by artificially evoked N2v bursts, a characteristic of CPG neurons. N2v cells have extensive input and output synaptic connections with the rest of the CPG network and the modulatory SO cell and cerebral giant cells (CGCs). Synaptic input from the protraction phase interneurons N1M (excitatory), N1L (inhibitory), and SO (inhibitory-excitatory) are likely to contribute to a ramp-shaped prepotential that triggers the N2v plateau. The prepotential has a highly complex waveform due to progressive changes in the amplitude of the component synaptic potentials. Most significant is the facilitation of the excitatory component of the SO --> N2v monosynaptic connection. None of the other CPG interneurons has the appropriate input synaptic connections to terminate the N2v plateaus. The modulatory function of acetylcholine (ACh), the transmitter of the SO and N1M/N1Ls, was examined. Focal application of ACh (50-ms pulses) onto the N2v cells reproduced the SO --> N2v biphasic synaptic response but also induced long-term plateauing (20-60 s). N2d cells show no endogenous ability to plateau, but this can be induced by focal applications of ACh. The N2v cells inhibit the N3 tonic (N3t) but not the N3 phasic (N3p) CPG interneurons. The N2v --> N3t inhibitory synaptic connection is important in timing N3t activity. The N3t cells recover from this inhibition and fire during the swallow phase of the feeding pattern. Feedback N2v inhibition to the SO, N1L protraction phase interneurons prevents them firing during the retraction phase of the feeding cycle. The N2v --> N1M synaptic connection was weak and only found in 50% of preparations. A weak N2v --> CGC inhibitory connection prevents the CGCs firing during the rasp (N2) phase of the feeding cycle. These data allowed a new model for the Lymnaea feeding CPG to be proposed. This emphasizes that each of the six types of CPG interneuron has a unique set of synaptic connections, all of which contribute to the generation of a full CPG pattern.

Acetylcholine↗

PubMed2003

Factor VIII inhibitor-bypassing agents act by inducing thrombin generation and can be monitored by a thrombin generation assay.

Factor VIII (FVIII)-bypassing agents have complex modes of action but all control bleeding in inhibitor patients by triggering the generation of thrombin. No routine test is available for monitoring this therapy in patients with inhibitors against FVIII. We present an assay that records FEIBA- or FVIIa-mediated changes in thrombin generation (TG) in FVIII inhibitor plasma samples. In plasma samples spiked with FEIBA TG was normalized above 0.4 U/ml, while for recombinant FVIIa (rFVIIa) more than 12.5 microg/ml were required to induce TG in the absence of tissue factor (TF). Addition of TF increased the TG potential of rFVIIa in vitro. This assay seems suitable for monitoring the pharmacokinetics of inhibitor bypassing agents during treatment and possibly for predicting responses to treatment.

Autoantibodies↗

PubMed2004

Generation of single-walled carbon nanotubes from alcohol and generation mechanism by molecular dynamics simulations.

Recent advances in high-purity and high-yield catalytic chemical vapor deposition (CVD) generation of single-walled carbon nanotubes (SWNTs) from alcohol are comprehensively presented and discussed on the basis of results obtained from both experimental and numerical investigations. We have uniquely adopted alcohol as a carbon feedstock, and this has resulted in high-quality, low-temperature synthesis of SWNTs. This technique can produce SWNTs even at a very low temperature of 550 degrees C, which is about 300 degrees C lower than the conventional CVD methods in which methane or acetylene is typically used. We demonstrate the excellence of the proposed alcohol catalytic CVD method for high-yield production of SWNTs when Fe-Co on USY-zeolite powder was used as a catalyst. At optimum CVD conditions, a SWNT yield of more than 40 wt % was achieved over the weight of the catalytic powder within the reaction time of 120 min. In addition to the advantages for mass production, this method is also suitable for the direct synthesis of high-quality SWNTs on Si and quartz substrates when combined with the newly developed liquid-based "dip-coat" technique to mount catalytic metals on the surface of substrates. This method allows easy and costless loading of catalytic metals without the need for any support or underlayer materials that were usually required in previous studies for the generation of a sufficient quantity of SWNTs on an Si surface. Finally, the result of molecular dynamics simulation for the SWNT growth process is presented to obtain a fundamental insight into the initial growth mechanism on the catalytic particles.

Alcohols↗

PubMed1989

Mourning and longing from generation to generation.

Violent sudden separation from their closest family members determined the extent of survivors' individual traumas. Uncompleted mourning and the depression and somber states of mind it created were absorbed by their children from birth on. Children of survivors react to the lack of memories and absence of dead family members. As full adults, an increasing, overt search for better knowledge and understanding is expressed and shared. This seems to contribute to free families of Holocaust survivors of the shame and guilt, and enables a deeper understanding of the entire phenomenon, as it is passed from generation to generation.

Adolescent↗

PubMed2026

GenOT: generative optimal transport enables spatiotemporal interpolation and generation in cross-platform spatial transcriptomics.

Spatial transcriptomics technologies have revolutionized the analysis of spatial gene expression, yet integrating spatial information and generating data across heterogeneous samples remain challenging. We present GenOT, a generative framework combining multi-scale graph self-supervised contrastive learning with optimal transport barycenter theory for efficient cross-slice and cross-platform spatiotemporal interpolation. The core innovation of GenOT lies in introducing an optimal transport barycenter-based interpolation algorithm, which mathematically models spatial distribution differences across heterogeneous samples to reconstruct spatiotemporal gene expression dynamics. Extensive evaluations demonstrate that GenOT consistently outperforms existing approaches in spatial domain identification, cross-platform interpolation, and developmental trajectory reconstruction.

Spatial Transcriptomics↗

PubMed2002

Nd:YAG-pumped periodically poled LiNbO3 optical parametric generator seeded with the narrowband output of a 532-nm pumped optical parametric generator.

We present a simple scheme to generate a continuously tunable pulsed narrow-bandwidth infrared wave. An Nd:YAG-pumped periodically poled lithium niobate optical parametric generator (OPG) is seeded with the output of another OPG pumped by the second harmonic (0.532 microm) of the Nd:YAG laser. A tunable idler wave from the 0.532-microm pumped OPG, operated away from the degenerate point, provides a narrow linewidth seed source for the 1.064-microm pumped broadband OPG. Seeding forces the second OPG to operate in a narrowband operation comparable with that of the seed source. Linewidth of the YAG-pumped OPG is 5-25 nm, in the tuning range of 1.61-1.83 microm (signal), narrowed to 1.48-1.05 nm. Methods of further reduction of linewidth also have been discussed.

Journal Article↗

PubMed2005

Optimal annular computer-generated holograms for the generation of optical vortices.

We analyze a method for efficiently generating optical vortices by use of annular computer-generated holograms and a spatial light modulator. We found that there exists an optimal annular width by which the reconstructed vortex ring in the focal plane has the steepest gradient and the worthless subbright rings can be largely suppressed. We fitted a general formula for determining the value of this optimal annular width and propose a method for designing a multiring structure of optical vortices and specialized interferometric vortex patterns. Finally, we discuss the situation of a Gaussian beam as illuminated light and find that there exists an optimal beam waist that results in the best energy efficiency.

Journal Article↗

PubMed2003

Broad-spectrum frequency comb generation and carrier-envelope offset frequency measurement by second-harmonic generation of a mode-locked fiber laser.

A frequency comb spanning more than one octave has been achieved by injecting the second-harmonic generation (780 nm) of a mode-locked fiber laser (1.56 microm) into a photonic crystal fiber. We propose and realize a novel interferometric scheme for observing the carrier-envelope offset frequency of the frequency comb. Frequency noise has been observed on the measured carrier-envelope offset frequency, which has been confirmed to be generated in the photonic crystal fiber by comparing the measured beat frequencies between cw lasers and frequency combs before and after the photonic crystal fiber. The mode-locked fiber laser is considered to be an important candidate for the light source used in realizing a compact optical frequency measurement system including applications in the telecommunication bands.

Journal Article↗

PubMed2005

Terahertz generation with tandem seeded optical parametric generators.

A simple difference frequency generation (DFG) scheme based on two seeded optical parametric generators is presented as a tunable terahertz (THz) source. Using the nonlinear optical crystal 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (DAST) as the DFG crystal, our system has demonstrated continuous and seamless tunable operation from 1.6 to 4.5 THz. The output bandwidth of the THz source is 2.4 GHz. The utility of the source over this spectral range is demonstrated by measuring a high-resolution transmission spectrum of water vapor in air.

Journal Article↗

PubMed1998

Should third-generation cephalosporins be the empirical treatment of choice for severe community-acquired pneumonia in adults?

The choice of empirical treatment for community-acquired pneumonia (CAP) is highly controversial. Our survey of 42 Australian emergency department doctors showed that monotherapy with a third-generation cephalosporin was the preferred regimen for severe CAP (14/42; 33%). We argue that cheaper regimens with a narrower spectrum are likely to be just as effective as third-generation cephalosporins and will have fewer adverse effects on the microbial ecology of hospitals. We suggest penicillin or ampicillin (to cover pneumococci--even if penicillin "resistant"--and Haemophilus influenzae), plus a macrolide (e.g., azithromycin or erythromycin; to cover Legionella and other "atypical" pathogens), plus a single large dose of an aminoglycoside (e.g., gentamicin; to cover gram-negative bacilli such as Klebsiella pneumoniae) as empirical therapy for severe CAP.

Adult↗

PubMed2001

Germ cell biology--from generation to generation.

Germ cells hold a unique place in the life cycle of animal species in that they are the cells that will carry the genome on to the next generation. In order to do this they must retain their DNA in a state in which it can be used to recapitulate embryonic development. In the normal life cycle, the germ cells are the only cells that retain this ability to recapitulate development, referred to as developmental totipotency. The molecular mechanisms regulating developmental potency are poorly understood. Recently its has been shown that germ cells can be turned into pluripotent stem cells when cultured in specific polypeptide growth factors that affect their survival and proliferation. The ability to manipulate developmental potency in germ cells with growth factors allows the underlying mechanisms to be dissected. Germ cells are also the only cells that undergo the unique reductive division of meiosis. This too is essential for the ability of germ cells to form the gametes that will carry the genome into the next generation. Arguably meiosis is the most important division in the life of a nascent organism. Defects in meiosis can result in embryonic or fetal loss or, if the animal survives, in the birth of an individual with chromosomal abnormalities. Recent advances in our understanding of meiosis have come from knockout mice and studies on genes identified through studies of human infertility. This review will focus on these two key aspects of germ cell biology, developmental potency and meiosis.

Animals↗

PubMed2002

Assessing match and mismatch between practitioner-generated and standardized interview-generated diagnoses for clinic-referred children and adolescents.

Although the Diagnostic and Statistical Manual of Mental Disorders (DSM) is widely used in both clinical and research settings, little is known about agreement between clinician and standardized research diagnoses. Diagnoses generated by the Diagnostic Interview Schedule for Children (DISC-P-2.3) were compared with clinician-generated diagnoses for 245 referred youths. Agreement was poor for all individual disorders and broader diagnostic clusters. Agreement was higher for externalizing categories than for internalizing, but no association was found between agreement and child, family, or clinician characteristics. Clinicians were more likely than the DISC to assign 1 diagnosis and less likely to assign 0 diagnoses, suggesting that clinic policies may play a role. Implications for the use of the DSM across different settings are discussed.

Adolescent↗

PubMed1992

Chairside computer-generated ceramic restorations: the Cerec third generation improvements.

Cerec chairside computer-generated ceramic restorations have well passed a five-year clinical observation period with convincing clinical success. The new system COS 2.1 allows an essentially automatic design of inlays, the construction of 3/4 and 4/5 cusp protection onlays, and individually-shaped aesthetic laminate veneers. The new E-drive grinding increases the machining capacity by factor 3 to 4, reduces edge roughness by 50%, and doubles machining precision. Cementation gap width at the cervical margin is 37-48 microns in normal-depth preparations and 54-76 microns in deep cavities. It is the purpose of this article to review the third generation improvements of this method.

Adult↗

PubMed1976

Generation of cytolytic T lymphocytes in vitro. VIII. failure of anti-RS antisera to inhibit the generation of cytolytic T lymphocytes or cytolytic T lymphocyte activity.

Antibody reactive with "recognition structures" (RS) of mouse lymphoid cells for alloantigens (anti-RS) was prepared by immunization of F1 hybrid mice with parentalstrain lymphoid cells or with antibody produced in one parental strain against alloantigens of the other parental strain. Such antisera prevented generation of the "product of antigenic recognition" (PAR) that is produced within a few hours in cultures prepared with a mixture of lymphoid cells from genetically disparate mice. However, treatment of responding lymphoid cells with anti-RS sera and complement did not inhibit generation of cytolytic T lymphocytes (CTL) in mixed lymphocyte cultures (MLC). Treatment of cells obtained from MLC with anti-RS sera and complement failed to inhibit cytolytic activity of such cells for specific alloantigens.

Animals↗

PubMedDate not supplied

[Reaction of posterity of two generations after exposure of pregnant Wistar rats to low dose irradiation during the period of fetus formation. Development of the first generation posterity].

Whole-body single exposure of female Wistar rats to 0.25, 0.5 and 1 Gy of gamma-rays (dose rate of 0.03 cGy/s) on the 10th day of pregnancy (a period of formation of the reproductive system in fetus) was carried out. To study irradiation consequences on the antenatal and postnatal development of the progeny 220 females, 700 19-day-old fetuses and about 1100 young rats were examined. The antenatal development of the progeny of the first generation was significantly impaired after the exposure to 1 Gy. However even less radiation doses resulted in a pronounced tendency to higher rates of intrauterine death and a lower number of live fetuses. Significant deviatins in the postnatal development of the first generation progeny were found after the exposure to 0.5 Gy, although the exposure to 0.25 Gy led to a higher rate of postnatal death and a less number of newborns in the litter.

Animals↗

PubMed2004

[The difference between the positive rate of anti-HCV in the patients with severe viral hepatitis detected by the first generation or second generation enzyme linked-immunosorbent assay].

OBJECTIVE: To compare the positive rate of antibody to hepatitis C virus (anti-HCV) in sera of patients with severe viral hepatitis between 1984-1990 year and 1997-2003 year. METHODS: Serum anti-HCV was detected by enzyme linked-immunosorbent assay (ELISA). It was detected by the first generation (1st) ELISA (Ortho Co. USA) in 79 cases of severe viral hepatitis during 1984-1990 year, and it was detected by the second generation (2nd) ELISA (Xiamen Xingchuang Co. China) in 251 cases of severe viral hepatitis during 1997-2003 year. RESULTS: The positive rate of serum anti-HCV was 51.9% detected by the 1st ELISA in 79 cases of severe viral hepatitis during 1984-1990 year, and it was 1.2% detected by the 2nd ELISA in 251 cases of severe hepatitis during 1997-2003 year (chi2 = 133.68, P </= 0.001). CONCLUSION: To compare with the positive rate of serum antibody to hepatitis C virus in severe viral hepatitis detected by the 1st ELISA, it was lower that detected by the 2nd ELISA

Adult↗

PubMed1979

Generation of effector cells from T cell subsets. I. Similar requirements for Lyt T cell subpopulations in the generation of alloreactive and H-2 restricted killer cells.

Lyt T cell subsets involved in the generation of H-2 restricted and alloreactive cytotoxic effector cells were analysed using anti Lyt antisera. Our data show that Lyt 1, 2, 3+ T cells are required for the induction of primary and secondary H-2 restricted and TNP-specific killer cells. In contrast, primary and secondary H-2 restricted and virus-specific T effector cells were obtained from selected Lyt 2, 3+ T cell populations and were not dependent on the presence of Lyt 1, 2, 3+ T cells. Allogeneic responses to selected K, I, or D region differences were obtained only in the presence of Lyt 1, 2, 3+ T cells; yet alloreactive killer cells were effectively generated from selected Lyt 2, 3+ T cell popluations deprived of Lyt 1, 2, 3+ T cells, when responder and stimulator cells differed at either K + D, K + I, I and D regionre is no qualitative difference between alloreactive and H-2 restricted cytotoxic responses in their requirements for particular Lyt T cell subsets. The findings indicate that the number of different antigenic determinants rather than their association with MHC self determinants is critical for the requirement of Lyt 1, 2, 3+ T cells during the sensitization phase.

Animals↗

PubMedDate not supplied

Improved waveform generator and cardiac simulator for sensitivity testing of ventricular programmed pulse generator.

The need for an easily generated, simulated QRS complex to facilitate preimplantation sensitivity testing of ventricular programmed pacemakers has led to the adoption of the sine squared waveform as the standard test pulse, by the Pacemaker Standards Subcommitte of the Association for the Advancement of Medical Instrumentation (AAMI). A simple circuit is presented that provides an accurate sine squared pulse with easily adjustable pulse width (base frequency). A suggested circuit for incorporating this sine squared pulse generator into a complete pacemaker test waveform generator/cardiac simulator is also presented.

Electronics↗