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At least 145 records · Page 8Linked to original sources
PubMed1989

Electrostimulation-induced fast-to-slow transitions of myosin light and heavy chains in rabbit fast-twitch muscle at the mRNA level.

Chronic low-frequency stimulation of rabbit fast-twitch muscle induces progressive increases in slow myosin light chain mRNAs followed by an increase in the slow myosin heavy chain HCI mRNA. Therefore, the effects of chronic stimulation are more pronounced in rabbit than in rat fast-twitch muscle. The latter responds mainly with a rearrangement of its fast isomyosin pattern.

Animals↗
PubMed2006

Silence of synaptotagmin I in INS-1 cells inhibits fast exocytosis and fast endocytosis.

Synaptotagmin I (Syt I) is a Ca(2+) sensor for triggering fast synchronized release of neurotransmitters. However, controversy remains whether Syt I is also obligatory for the exocytosis and endocytosis of larger dense core vesicles (LDCVs) in endocrine cells. In this study, we used a short hairpin RNA (shRNA) to silence the expression of Syt I and investigated the roles of Syt I on exocytosis and endocytosis in INS-1 cells. Our results demonstrated that expression of Syt I is remarkably reduced by the Syt I gene targeting shRNA. Using high-time resolution capacitance measurement, we found that the silence of Syt I decreased the calcium sensitivity of fusion of insulin granules and therefore reduced the exocytotic burst triggered by step-like [Ca(2+)](i) elevation. In addition, the occurrence frequency and amplitude of fast endocytosis were remarkably reduced in the silenced cells. We conclude that Syt I not only participates in the Ca(2+)-sensing of LDCV fusion with plasmalemma, but also plays a crucial role in fast endocytosis in INS-1 cells.

Animals↗
PubMedDate not supplied

Evaluation of focal liver lesions: fast-recovery fast spin echo T2-weighted MR imaging.

PURPOSE: To compare breath-hold fast-recovery fast spin echo (FR-FSE) and non-breath-hold fast spin echo (FSE) T2-weighted sequences for hepatic lesion conspicuity and image quality at MR imaging. MATERIALS AND METHODS: Fifty-nine patients with known or suspected liver lesions underwent hepatic MR imaging by using a breath-hold FR-FSE T2-weighted sequence with and without fat suppression and a non-breath-hold FSE T2-weighted sequence with and without fat suppression. Quantitative analysis was made with measurements of the signal intensity of the liver, spleen, background noise, and up to three liver lesions, as well as calculations of the liver signal-to-noise ratio (SNR) and the liver-to-lesion contrast-to-noise ratio (CNR) for each sequence. Qualitative analysis was made for image quality and the number of lesions identified. Statistical analysis was performed by using a single-tailed paired Student's t test with a 95% confidence interval. RESULTS: SNR and CNR were significantly higher (P<.05) for FSE with fat suppression than for FR-FSE with fat suppression. No statistically significant difference was seen in terms of SNR and CNR between non-fat-suppressed FSE and FR-FSE sequences. Lesion conspicuity, liver edge sharpness, and clarity of vessels were superior and ghosting was less with the FR-FSE sequences compared with the FSE sequences. CONCLUSION: Breath-hold FR-FSE technique is a reasonable alternative in T2-weighted imaging of the liver.

Adipose Tissue↗
PubMedDate not supplied

Potential phasic and tonic muscles express a common set of fast and slow myosin light chains and fast tropomyosin during early development of chick embryo.

We investigated the expression of myosin light chains and tropomyosin subunits during chick embryonic development of the anterior (ALD) and posterior (PLD) parts of the latissimus dorsi muscles. As early as day 8 in ovo, both muscles accumulate a common set of myosin light chains (LC) in similar ratios (LC1F: 55 per cent; LC2S: 25 per cent; LC2F: 12 per cent; LC1S: 8 per cent) and a common set of tropomyosin (TM) subunits (beta 2, beta 1, alpha 2F). Later during development, the slow components of the LC regularly disappear in the PLD and the fast components of the LC and the alpha 2FTM disappear in the ALD, so that the adult pattern is almost established at the time of hatching. Thus, early in development, the two muscles accumulate a common set of fast and slow myosin light chains and fast tropomyosin and some isoforms are repressed at a later stage during development. These data might suggest that during development, the regulatory mechanisms of muscle specific isoform expression differ from one contractile protein to another.

Animals↗
PubMed1997

Fast flair imaging of the brain using the fast spin-echo and gradient spin-echo technique.

The purpose of this study was to compare the gradient spin-echo (GRASE) to the fast spin-echo (FSE) implementation of fast fluid-attenuated inversion recovery (FLAIR) sequences for brain imaging. Thirty patients with high signal intensity lesions on T2-weighted images were examined on a 1.5 T MR system. Scan time-minimized thin-section FLAIR-FSE and FLAIR-GRASE sequences were obtained and compared side by side. Image assessment criteria were lesion conspicuity, contrast between different types of normal tissue, image quality, and artifacts. In addition, contrast ratios and contrast-to-noise ratios were determined. Compared to FSF, the GRASE technique allowed a 17% reduction in scan time but conspicuity of small lesions in particular was significantly lower on FLAIR-GRASE images because of higher image noise and increased artifacts. Gray-white differentiation was slightly worse on FLAIR-GRASE. Physiological ferritin deposition appeared slightly darker on FLAIR-GRASE images and susceptibility artifacts were stronger. Fatty tissue was less bright with FLAIR-GRASE. With current standard hardware equipment, the GRASE technique is not an adequate alternative to FSE for the implementation of fast FLAIR sequences in routine clinical MR brain imaging.

Brain↗
PubMed2001

Potential for the speciation of Zn using fast protein liquid chromatography (FPLC) and convective interaction media (CIM) fast monolithic chromatography with FAAS and electrospray (ES)-MS-MS detection.

Analytical procedures were developed for the speciation of Zn using fast protein liquid chromatography (FPLC), flame atomic absorption spectrometry (FAAS) and convective interaction media (CIM) fast monolithic chromatography with FAAS and electrospray (ES)-MS-MS detection. The investigation was performed on synthetic solutions (2 microg cm-3 Zn) of hydrated Zn2+ species and Zn complexes with citrate, oxalate and EDTA (ligand-to-Zn molar ratio 100:1) over a pH range from 5.4 to 7.4. It was found that Zn interacts with various buffers and the careful adjustment of the pH with diluted solutions of KOH is, therefore, required. FPLC separations were carried out on a Mono Q HR 5/5 strong anion-exchange column, applying an aqueous 1 mol dm(-3) NH4NO3 linear gradient elution over 15 min, at a flow rate of 1.0 cm3 min(-1). The separated Zn species were determined in 1.0 cm3 eluate fractions "off line" by FAAS. Speciation of Zn was also performed on a weak anion-exchange CIM DEAE fast monolithic disc by applying an aqueous 0.4 mol dm(-3) NH4NO3 linear gradient elution over 7.5 min, at a flow rate of 2.0 cm3 min(-1) and determination of the separated Zn species in 1.0 cm3 eluate fractions "off line" by FAAS. Zn-binding ligands in separated fractions were also characterized by electrospray (ES)-MS-MS analysis. The CIM DEAE disc was found to be more efficient in the separation of negatively charged Zn complexes than the Mono Q FPLC column. On the CIM DEAE disc Zn-citrate was separated from both Zn-oxalate and from Zn-EDTA. All these species were also separated from hydrated Zn2+, which was eluted with the solvent front. This method has an advantage over commonly used analytical techniques for the speciation of Zn which are only able to distinguish between labile and strong Zn complexes. Good repeatability of the measurements (RSD 2-4%), tested for six parallel determinations (2 microg cm(-3) Zn) of Zn-EDTA, Zn-citrate and Zn-oxalate was found at a pH of 6.4 on a CIM DAEA disc. The limit of detection (3s) for the separated Zn species was 10 ng cm(-3). The proposed analytical procedure was applied to the speciation of Zn in aqueous soil extracts and industrial waste water from a lead and zinc mining area.

Journal Article↗
PubMed2025

PseudotimeDE-fast: fast testing of differential gene expression along cell pseudotime.

SUMMARY: Identifying differentially expressed (DE) genes along cell pseudotime is crucial for understanding dynamic biological processes captured by single-cell RNA sequencing. However, existing DE methods either produce invalid P-values by ignoring the uncertainty in pseudotime inference or struggle to scale with the growing size of modern datasets. To address these limitations, we introduce PseudotimeDE-fast, a scalable method for detecting DE genes along pseudotime with well-calibrated P-values. Through comprehensive simulations and real-data analyses, we demonstrate that PseudotimeDE-fast delivers comparable or superior performance to existing approaches while offering substantial improvements in computational efficiency. AVAILABILITY AND IMPLEMENTATION: PseudotimeDE-fast is implemented in R with Rcpp acceleration and released under the MIT license. The source code is available at: https://github.com/dsong-lab/PseudotimeDE.

Single-Cell Analysis↗
PubMed1995

Fast spin-echo inversion-recovery imaging versus fast T2-weighted spin-echo imaging in bone marrow abnormalities.

RATIONALE AND OBJECTIVES: The purpose of this investigation is to compare a fat-suppressed T2-weighted fast spin-echo (FSE) sequence in bone marrow abnormalities with an FSE STIR sequence that recently has become commercially available. METHODS: Fast spin-echo images (repetition time [TR], 3500-5000 mseconds; echo time [TE], 96-114 mseconds) and FSE STIR images (TR, 3000-5000 mseconds; TE, 32-40 mseconds; inversion time [TI], 140-150 mseconds) were compared quantitatively and qualitatively calculating signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), and lesion conspicuity and using a qualitative scoring system. RESULTS: Signal-to-noise ratio (mean +/- standard deviation) was 36.4 +/- 19.3 for the FSE and 29.0 +/- 15.9 for the FSE STIR images (P = .002). Contrast-to-noise ratio (mean +/- standard deviation) was 18.7 +/- 14.3 for the FSE and 20.3 +/- 16.0 for the FSE STIR images (P = .45). Lesion conspicuity (mean +/- standard deviation) was 1.7 +/- 1.5 for the FSE and 3.5 +/- 4.0 for the FSE STIR images (P = .025). The most important difference in the qualitative evaluation related to the better signal homogeneity on the FSE STIR images. CONCLUSIONS: Fast spin-echo STIR images may be preferable to FSE images with fat suppression due to better image homogeneity and lesion conspicuity.

Adolescent↗
PubMed2000

Electron boltzmann kinetic equation averaged over fast electron bouncing and pitch-angle scattering for fast modeling of electron cyclotron resonance discharge

The electron distribution function (EDF) in an electron cyclotron resonance (ECR) discharge is far from Maxwellian. The self-consistent simulation of ECR discharges requires a calculation of the EDF on every magnetic line for various ion density profiles. The straightforward self-consistent simulation of ECR discharges using the Monte Carlo technique for the EDF calculation is very computer time expensive, since the electron and ion time scales are very different. An electron Boltzmann kinetic equation averaged over the fast electron bouncing and pitch-angle scattering was derived in order to develop an effective and operative tool for the fast modeling (FM) of low-pressure ECR discharges. An analytical solution for the EDF in a loss cone was derived. To check the validity of the FM, one-dimensional (in coordinate) and two-dimensional (in velocity) Monte Carlo simulation codes were developed. The validity of the fast modeling method is proved by comparison with the Monte Carlo simulations. The complete system of equations for FM is presented and ready for use in a comprehensive study of ECR discharges. The variations of plasma density and of wall and sheath potentials are analyzed by solving a self-consistent set of equations for the EDF.

Journal Article↗
PubMed2000

Self-organized localization of macrostates by additive noise in a fast-slow dynamical system: effect of the slow nonreactive mode on the barrier crossing rate of the fast, bistable mode

We have studied the stochastic dynamics of a two-dimensional gradient system composed of a fast, bistable mode and a slow, monotonically decaying mode. The coupling is bidirectional and cooperative. Additive white noise acts on the fast mode only. We find that the noise intensity controls the location of macrostates (shape of the probability density function), the appearance of bimodality in the slow-mode probability distribution and, together with the coupling strength, the rate of fast-mode barrier crossing. These features arise from the interplay of noise, widely separated time scales, and bidirectional, excitatory coupling. They are believed to be generic.

Journal Article↗
PubMed2002

Fast recovery 3D fast spin-echo MR imaging of the inner ear at 3 T.

High-resolution MR imaging of the inner ear with a heavily T2-weighted 3D fast spin-echo sequence has been performed successfully at 1.5 T. However, at 3 T, the longer T1 time of CSF necessitates a longer TR, resulting in significantly prolonged imaging times. In this study, the fast recovery 3D fast spin-echo sequence, which permits the TR to be reduced while maintaining T2 contrast, was optimized at 3 T for imaging of the inner ear. The optimized sequence parameters are as follows: 1500/294 (TR/TE); echo spacing, 18.1 ms; bandwidth, 38 kHz at 512 readout; and imaging time, 13 minutes.

Ear, Inner↗
PubMed2004

3-T imaging of the cochlear nerve and labyrinth in cochlear-implant candidates: 3D fast recovery fast spin-echo versus 3D constructive interference in the steady state techniques.

BACKGROUND AND PURPOSE: High-resolution imaging of the internal auditory canal and labyrinth at 1.5 T is often performed by using three-dimensional (3D) fast spin-echo or T2* techniques. We evaluated both techniques at 3 T in the preoperative assessment of patients being considered for cochlear implants. METHODS: Sagittal 3D fast recovery fast spin-echo (FRFSE) and 3D constructive interference in the steady state (CISS) images were acquired in eight patients at 3.0 T by using dual surface coils. Contrast-to-noise ratios (CNRs) for the intracanalicular nerve and CSF were measured in the internal auditory canal. Two neuroradiologists reviewed the images to determine whether the techniques provided images of diagnostic quality. RESULTS: CNRs for 3D CISS were twice those obtained with 3D FRFSE. Both techniques provided images of diagnostic quality, though spurious signal intensity loss at the apex of the superior semicircular canals was encountered on 3D FRFSE images in four of eight patients. CONCLUSION: Both 3D FRFSE and 3D CISS provide high-resolution images of the internal auditory canal and labyrinth at 3.0 T. We predict that the superior CNRs obtained with 3D CISS will prove advantageous as we move to smaller fields of view at higher field strength.

Artifacts↗
PubMed1995

[Fast and ultra-fast MRI of the brain].

Fast spin-echo sequences, which are based on the RARE sequence, accelerate MRI significantly. The basic principle of fast- or turbo-spin-echo sequences (FSE, TSE), as well as of the gradient-and-spin-echo sequences (GRASE, TGSE), is the sampling of multiple independently phase-encoded echos after each excitation. The basic principles of these sequences and the potentials and limitations of their clinical application are discussed. Their main advantage is a significant reduction of the time for data acquisition, which allows either a reduction of imaging time or high-resolution images even with T2-weighting. The fast sequences provide all possibilities of contrast variation and of preparation pulses such as fat saturation or water suppression. Despite some restrictions, of which reduced susceptibility is clinically relevant, they can replace conventional spin-echo sequences in brain imaging.

Brain↗
PubMed1997

[Technical aspects of fast, ultra-fast MR imaging].

Technical aspects of fast, ultra-fast MR imaging are described. Firstly, mechanism of steady state MR signals, generated by rf pulses with short repetition times, are focused, and described that the steady state signal contains echo signals that have different history. Imaging pulse sequence utilizing the steady state signals is referred to as Gradient Recalled Echo (GRE) sequence. Secondly, in order to give general description for echo train imaging sequences, concept of k-space and k-space trajectory is introduced. The concept is useful to realize how echo train imaging sequences such as echo planar imaging and fast spin echo imaging collect raw data efficiently.

Humans↗
PubMed1997

Fine mapping of five human skeletal muscle genes: alpha-tropomyosin, beta-tropomyosin, troponin-I slow-twitch, troponin-I fast-twitch, and troponin-C fast.

In this paper the chromosomal localization of the human skeletal muscle genes Troponin-I slow-twitch (TNNI1), Troponin-I fast-twitch (TNNI2), and Troponin-C fast (TNNC2) and the refinement of the position for alpha-Tropomyosin (TPM1) and beta-Tropomyosin (TPM2) are reported. By radiation hybrid mapping, TPM1 was assigned to chromosome 15q22.1, TPM2 to chromosome 9p13.2-p13.1, TNNI1 to chromosome 1q31.3, TNNI2 to chromosome 11p15.5, and TNNC2 to chromosome 20q12-q13.11. The genomic distribution of these genes is discussed, with particular emphasis on the cluster organization of the Troponin genes.

Base Sequence↗
PubMedDate not supplied

Insulinoma: clinical manifestations, diagnosis and treatment. The significance of the prolonged fasting test and of the fasting blood glucose-insulin relationship.

This paper describes the clinical manifestations and the significance of the fasting blood glucose-insulin relationship and the prolonged fasting test in the diagnosis of insulinoma. Pre-and postoperative results are reported. In addition, a description is given of the angiographic demonstration and the results of the surgical removal of the insulinomas.

Adenoma, Islet Cell↗
PubMed1981

Plasma cortisol concentrations after oral substitution of cortisone in the fasting and non-fasting state.

Nine corticosteroid-substituted patients received oral cortisone acetate in the fasting state and together with a breakfast meal. Plasma cortisol concentrations were determined before, after 30 min, and at 1-hour intervals until 6 hours after drug ingestion. There were great interindividual variations in the time to peak values (tmax), the peak concentrations (Cmax), and the areas under the time-concentration curves (AUC0--6h). The AUC and Cmax values were significantly increased when cortisone tablets were ingested with food compared to the values obtained in the fasting state (p less than 0.01 and p less than 0.05 respectively), whereas tmax values were not significantly different. The differences were minor and probably without clinical implications.

Addison Disease↗
PubMed2006

Comparison of the effects of fasting morning, fasting evening and fed bedtime administration of tenatoprazole on intragastric pH in healthy volunteers: a randomized three-way crossover study.

BACKGROUND: The effectiveness of proton pump inhibitors is influenced by meals and administration time. AIM: To compare the effects on intragastric acidity of times of dosing of tenatoprazole, a novel imidazopyridine-based proton pump inhibitor with a prolonged plasma half-life. METHODS: This randomized three-period crossover study included 12 Helicobacter pylori-negative healthy subjects, who received tenatoprazole 40 mg either fasting at 7.00 AM, fasting at 7.00 PM or fed at 9.30 PM for 7 days, with a 2-week washout between periods. Twenty-four hour intragastric pH was monitored on day 7 of each period. RESULTS: On day 7, median 24-h pH was 4.7, 5.1 and 4.7 after breakfast, dinner and bedtime dosing, respectively (P = 0.11), whereas night-time pH was 4.2, 5.0 and 4.4 (P = 0.13). The mean 24-h percentage of time over pH 4 was 62, 72 and 64 after breakfast, dinner and bedtime dosing, respectively (N.S.), and 54, 68 and 56 during night-time (P = 0.06). Nocturnal acid breakthrough incidence decreased from 100% at baseline to 83%, 55% and 75% after 7.00 AM, 7.00 PM and 9.30 PM dosing, respectively (P = 0.18), and its mean duration dropped from 6.2 to 2.8, 1.0 and 2.2 h, respectively (P < 0.05). CONCLUSION: Seven-day administration of tenatoprazole provides a prolonged duration of acid suppression, especially during the night-time, with little effect of food or time of dosing.

2-Pyridinylmethylsulfinylbenzimidazoles↗