Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Miniaturization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,315 records · Page 73Linked to original sources
PubMed2000

Activity-dependent enhancement of miniature excitatory postsynaptic current amplitude and its modulation by protein kinase C in cultured rat sympathetic neurons.

A high K+ solution increased the frequency of miniature excitatory postsynaptic currents (MEPSCs) and intracellular Ca2+ concentration ([Ca2+]i) in cultured rat sympathetic neurons. Repetition or continuation of high K+ treatment increased MEPSC amplitude, acetylcholine-induced currents and the averaged rise in [Ca2+]i per single MEPSC. The enhancement of MEPSCs lasted over 30 min and was inhibited by intracellular BAPTA and phorbol ester, but not by atropine. The results suggest that repeated Ca2+ entry through the channel pore of nicotinic acetylcholine receptor enhances the efficacy of its opening and the activation of protein kinase C inhibits the enhancement.

Acetylcholine↗
PubMed2000

Presynaptic inhibition by baclofen of miniature EPSCs and IPSCs in substantia gelatinosa neurons of the adult rat spinal dorsal horn.

Intrathecal administration of baclofen, a GABA(B)-receptor agonist, affects pain behavior induced by formalin in a biphasic manner; baclofen at low doses enhances pain while producing antinociception at high doses. This may be due to the fact that baclofen modulates each of excitatory and inhibitory transmission in the dorsal horn of the spinal cord with a distinct sensitivity, resulting in a biphasic action on pain transmission. To address this issue, we examined the actions of baclofen on miniature excitatory (glutamatergic) and inhibitory (GABAergic) postsynaptic currents (mEPSCs and mIPSCs, respectively) in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole-cell voltage-clamp technique. Baclofen reduced the frequency of both mEPSC and mIPSC without a change in their amplitudes. These actions were dose-dependent in a concentration range of 0.1-100 microM; the effective concentrations for the half-inhibition of mEPSC and mIPSC frequency were 4.44+/-0. 60 microM (n=7) and 4.31+/-0.77 microM (n=6), respectively. These results indicate that each of glutamatergic and GABAergic nerve terminals in the SG is endowed with the GABA(B) receptor, the activation of which depresses the release of neurotransmitter from the terminal; this provides a cellular basis for the modulation of pain by baclofen. It is suggested from a similar affinity for baclofen of the GABA(B) receptors on both terminals that the baclofen-induced biphasic action on pain behaviors cannot be accounted for by only its presynaptic actions in the SG and that other actions such as an inhibitory action of baclofen on postsynaptic neurons also have to be taken into consideration.

Animals↗
PubMed2002

Presynaptic inhibition of GABAergic miniature currents by metabotropic glutamate receptor in the rat CNS.

The modulation of spontaneous miniature GABAergic inhibitory postsynaptic currents (mIPSC) by the metabotropic glutamate receptors was investigated in the mechanically dissociated rat nucleus basalis of Meynert neurons using the conventional whole-cell patch recording configuration. An application of (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (tACPD) reversibly reduced the frequency of mIPSC without affecting the current amplitude distribution. The application of K+ channel blockers such as 4-aminopyridine, Cs+, Ba2+ or tetraethylammonium increased the mIPSC frequency, but failed to inhibit the tACPD action on mIPSC. Although the removal of Ca2+ from the extracellular solution reduced the mIPSC frequency, the inhibitory effect of tACPD on mIPSC was unaltered. These results suggested that neither voltage-dependent K+ or Ca2+ channels are involved in the inhibitory effect of tACPD on mIPSC frequency. Forskolin, an activator of adenylate cyclase, facilitated the mIPSC frequency in a concentration-dependent manner and inhibited the tACPD-induced suppression of mIPSC frequency. 8-Br-cAMP, a membrane permeable analog of cAMP, also prevented the inhibitory action of tACPD. However, Sp-cAMP, an activator of protein kinase A, could not prevent the inhibitory action of tACPD. L-CCG-I and (2R,4R)-APDC, group II mGluR agonists, mimicked the tACPD action on mIPSC frequency, but L-AP4, a group III mGluR agonist, had no such effect. MCCG, a group II mGluR antagonist, fully blocked the tACPD action. It was concluded that the activation of group II mGluR on the GABAergic presynaptic nerve terminals projecting to the rat nucleus basalis of Meynert neurons therefore inhibits the GABA release by reducing the activity of the cAMP-dependent pathway.

Adenylyl Cyclases↗
PubMed2001

Miniature data loggers for remote measurement of body temperature in medium-sized rodents.

We have investigated the use of miniature temperature data loggers for the recording of abdominal temperature in laboratory animals, using the guinea pig as a model. The data loggers, which are small (16cm(3)), light (20g) and have a battery life of +/-5 years, recorded both the normal abdominal temperature of guinea pigs, and their febrile response to an intramuscular injection of 50µg/kg lipopolysaccharide (E. coli) every 5min for the duration of the experiment (21 days), to a resolution of at least 0.05 degrees C. No calibration shifts or loss of data occurred during the study period. However, despite their small size and versatility, we found that the loggers were suited for use only in guinea pigs with a body mass of approximately 600g or greater. In smaller animals, the loggers caused peritonitis.

Journal Article↗
PubMed1997

Comparison of miniature multileaf collimation (MMLC) with circular collimation for stereotactic treatment.

PURPOSE: A prototype Miniature Multi-Leaf Collimator (MMLC) designed specifically for radiosurgery and small field radiotherapy has been fabricated and evaluated at the University of Texas M. D. Anderson Cancer Center (UTMDACC). This work demonstrates the advantages of a computer-controlled MMLC vs. conventional circular collimation for the treatment of an irregularly shaped target volume in the brain. METHODS AND MATERIALS: Two patient treatments were selected for this comparison from 38 intracranial tumors treated with radiosurgery at UTMDACC from 8/6/91 to 5/10/94. Target contours and critical structures defined for one of the patients was used to create a simulated target volume and critical structures in a spherical head phantom. Computer simulations were performed using traditional single isocenter treatment with a circular collimator for a set of six arcs. The same arc paths were used to compute the dose distribution for the MMLC and conformed beam geometries were defined using a three-dimensional (3D) treatment planning system with beam's eye view capabilities. Then, the calculated dose distribution for a single isocenter, conformal treatment was delivered to the spherical head phantom under static conditions by shaping the MMLC to conform the target volume shape projected as a function of couch rotation and gantry angle. Planar dose distributions through the target volume were measured using therapy verification film located in the phantom. The measurements were used to verify that the 3D treatment planning system was capable of simulating the MMLC technique. For the second patient with a peanut-shaped tumor, the 3D treatment planning calculations were used to compare dose distributions for the MMLC and for traditional single and multiple isocenter treatments using circular collimators. The resulting integral dose-volume histograms (DVHs) for the target volume, normal brain, and critical structures for the three treatment techniques were compared. RESULTS: (a) Analysis of the film dosimetry data exemplified the degree of conformation of the high-dose region to the target shape that is possible with a computer-controlled MMLC. (b) Comparison of measured and calculated dose distributions indicates that the 3D treatment planning system can simulate the MMLC treatment. (c) Comparison of DVHs from the single isocenter MMLC and circular collimator treatments shows similar coverage of the target volume with increased dose to the brain for circular collimation (4). Comparison of DVHs from the single isocenter MMLC with the multiple isocenter circular collimator treatment approach shows a more inhomogeneous dose distribution through the target volume and increased dose to the brain for the latter. CONCLUSION: Dosimetry data for single isocenter treatments using computer-controlled field shaping with a MMLC demonstrate the ability to conform the dose distribution to an irregularly shaped target volume. DVHs validated that the single isocenter MMLC treatment is preferable to both single and multiple isocenter, circular collimator treatment because it provides a more uniform dose distribution to an irregularly shaped target volume and reduces the dose to surrounding brain tissue for the example cases.

Adenocarcinoma↗
PubMed1986

Fixation of metacarpal and phalangeal fractures with miniature plates and screws.

Fifty-two unstable metacarpal and phalangeal fractures were treated with miniature plates and screws as internal fixation devices with excellent results based on the criteria of the American Society for Surgery of the Hand (total active range of motion greater than 220 degrees). This technique stabilizes the skeleton, preserves the gliding tissues, and thus allows immediate active range of motion exercises. Transverse, spiral, oblique, and condylar fractures of the metacarpals and phalanges are best suited for this method.

Adolescent↗
PubMed2000

Recent amplification of miniature inverted-repeat transposable elements in the vector mosquito Culex pipiens: characterization of the Mimo family.

We describe a new family of repetitive elements, named Mimo, from the mosquito Culex pipiens. Structural characteristics of these elements fit well with those of miniature inverted-repeat transposable elements (MITEs), which are ubiquitous and highly abundant in plant genomes. The occurrence of Mimo in C. pipiens provides new evidence that MITEs are not restricted to plant genomes, but may be widespread in arthropods as well. The copy number of Mimo elements in C. pipiens ( approximately 1000 copies in a 540Mb genome) supports the hypothesis that there is a positive correlation between genome size and the magnitude of MITE proliferation. In contrast to most MITE families described so far, members of the Mimo family share a high sequence conservation, which may reflect a recent amplification history in this species. In addition, we found that Mimo elements are a frequent nest for other MITE-like elements, suggesting that multiple and successive MITE transposition events have occurred very recently in the C. pipiens genome. Despite evidence for recent mobility of these MITEs, no element has been found to encode a protein; therefore, we do not know how they have transposed and have spread in the genome. However, some sequence similarities in terminal inverted-repeats suggest a possible filiation of some of these mosquito MITEs with pogo-like DNA transposons.

Animals↗
PubMed2001

Whole-genome organization and functional properties of miniature DNA insertion sequences conserved in pathogenic Neisseriae.

The chromosome of pathogenic Neisseriae is peppered by members of an abundant family of small DNA sequences known as Correia elements. These DNA repeats, that we call nemis (for neisseria miniature insertion sequences) can be sorted into two major size classes. Both unit-length (154-158 bp) and internally rearranged (104-108 bp) elements feature long terminal inverted repeats (TIRs), and can potentially fold into robust stem-loop structures. Nemis are (or have been) mobile DNA sequences which generate a specific 2-bp target site duplication upon insertion, and strictly recall RUP, a repeated DNA element found in Streptococcus pneumoniae. The subfamilies of 26L/26R, 26L/27R, 27L/27R and 27L/26R elements, found by wide-genome computer surveys in both the Neisseria meningitidis and the Neisseria gonorrhoeae genomes, originate from the combination of TIRs which vary in length (26-27 bp) as in sequence content (L and R types). In both species, the predominant subfamily is made by the 26L/26R elements. The number of nemis is comparable in the N. meningitidis Z2491 (A serogroup) and the MC58 (B serogroup) strains, but is sharply reduced in the N. gonorrhoeae strain F1090. Consequently, several genes which are conserved in the two pathogens are flanked by nemis DNA in the meningococcus genome only. More than 2/3 of nemis are interspersed with single-copy DNA, and are found at close distance from cellular genes. Both primer extension and RNase protection data lend support to the notion that nemis are cotranscribed with cellular genes and subsequently processed, at either one or both TIRs, by a specific endoribonuclease, which plausibly corresponds to RNase III.

Base Sequence↗
PubMed1980

Miniature two-dimensional thin-layer chromatographic separation of lecithin and sphingomyelin.

A miniature two-dimensional thin-layer chromatographic procedure employing silica gel impregnated glass-microfiber chromatography sheets (commercial product, ITLC-type SG sheets) has been developed for the separation of lecithin (L) and sphingomyelin (S) from a standard lipid mixture containing L, S, lysolecithin, phosphatidyl inositol (PI), phosphatidyl serine (PS), phosphatidyl ethanolamine, phosphatidyl glycerol, and diphosphatidyl glycerol. The newly developed procedure eliminates possible interference from PI and PS. Complete separation of L and S was easily achieved with chromatographic solvent migration times of approximately 3 and 2 min for the first and second dimensions, respectively. The lipids were visualized by charring and fluorescent staining techniques. The procedure has been adapted for the separation of L and S from amniotic fluid samples.

Amniotic Fluid↗
PubMed2001

Medium-term results of implantable miniaturized telescopes in eyes with age-related macular degeneration.

PURPOSE: To evaluate the efficacy of an implantable miniaturized telescope, the IMT, in patients with age-related macular degeneration (ARMD). SETTING: Ege University Faculty of Medicine, Ophthalmology Department, Izmir, Turkey. METHODS: Among 15 patients meeting the inclusion criteria for IMT implantation, 3 were willing to participate in this prospective clinical trial and had cataract extraction with IMT implantation. The effect of the IMT on visual outcome and daily activities was assessed over 18 months. RESULTS: All patients had some improvement in distance and near vision. However, this did not lead to significant improvements in the ability to perform daily activities. One patient had 2 attacks of mild iritis that were controlled with topical medications. In another patient, bubbles that were noted inside the IMT soon after implantation were still present at 1 year. In this patient, the IMT was replaced with a conventional poly(methyl methacrylate) intraocular lens. CONCLUSIONS: Implantation of an IMT may positively affect the visual outcome and daily activities in some ARMD patients. However, proper patient selection and fully informed patient consent and understanding are mandatory.

Aged↗
PubMed2003

Feasibility and safety of laser treatments in eyes with an intraocular implantable miniature telescope.

PURPOSE: To evaluate the feasibility and safety of laser treatments in rabbit eyes fitted with an implantable miniature telescope (IMT). SETTING: The Goldschleger Eye Research Institute, Tel-Aviv University, Sheba Medical Center, Tel-Hashomer, Israel. METHODS: In this study, IMTs were implanted in the capsular bag in 19 eyes of 19 pigmented rabbits. After the rabbits recovered from surgery, neodymium:YAG (Nd:YAG) laser iridectomy (4 eyes), Nd:YAG laser capsulotomy (8 eyes), or argon laser photocoagulation of the retina (6 eyes) was performed. One day after the laser treatment, the rabbits were killed. An observer blinded to the treatment received by individual rabbits examined the enucleated eyes histopathologically to evaluate the laser lesions and their effect on ocular tissues. RESULTS: Laser iridectomy and laser posterior capsulotomy were carried out without difficulty. Laser photocoagulation of the posterior pole and the retinal periphery could be accomplished only when the laser beam was aimed around the optic of the IMT. It was not possible to carry out effective laser treatment of the retina through the IMT's optic. Treatment was difficult when adhesions between the pupil margin and the IMT optic were encountered. CONCLUSIONS: Standard laser treatments in eyes with an IMT in the capsular bag were feasible in pigmented rabbits, whose eyes are a good model for the eyes of human patients. Laser treatment of the retina was difficult to perform when adhesions between the pupil margin and the IMT were present.

Animals↗
PubMed1998

Body position can be monitored in 3D using miniature accelerometers and earth-magnetic field sensors.

OBJECTIVES: The study and diagnosis of movement disorders can be improved by monitoring body position simultaneously with the EMG. METHODS: We developed a monitor of the 3-dimensional (3D) orientation of body parts that can be applied in long-term ambulatory recordings in the daily life of a patient. The 3D sensor combines miniature sensors for earth's gravity and magnetism. It measures 60 x 50 x 10 mm and draws less than 1 mA of current from +/-5 V battery power. The non-horizontal direction of earth magnetism, as well as torque (pronation) of the body part, is corrected mathematically. RESULTS: This results in a measurement of the 3D orientation of a body part in terms of vertical inclination and horizontal azimuth. CONCLUSIONS: Calibration measurements indicate that this method is fairly accurate and practically applicable.

Acceleration↗
PubMed1998

Construction of biosensors using a gold-binding polypeptide and a miniature integrated surface plasmon resonance sensor.

Surface plasmon resonance (SPR) biosensors were constructed on miniature integrated sensors. Recognition elements were attached to the sensor surface using a gold-binding repeating polypeptide. Biosensors with fluorescyl groups attached to their surfaces were functional for at least 1 month of daily use with little decrease in response to the binding of an anti-fluorescyl monoclonal antibody. The coupling of protein A to the gold-binding polypeptide on the sensor surface enabled the biosensor to detect the binding of antibodies to the protein A and provided a sensor with convertible specificity. The system described herein provides a simple and rapid approach for the fabrication of highly specific, durable, portable and low cost SPR-based biosensors.

Amino Acid Sequence↗
PubMed2001

Miniaturized EI/Q/oa TOF mass spectrometer.

A miniaturized orthogonal time-of-flight mass spectrometer with an electron impact ionization ion source and a rf quadrupole ion guide has been developed. A mass resolving power of m/deltam = 5500 has been obtained in a 0.4 m instrument. The addition of helium at pressures of about 4.0 mtorr into the ion source showed collisional focusing taking place in the rf quadrupole. An automated gas chromatograph designed for air monitoring applications has been coupled to the time-of-flight mass analyzer and tested for the detection of simulants of chemical-warfare agents.

Journal Article↗
PubMed1999

High-throughput screening of small molecules in miniaturized mammalian cell-based assays involving post-translational modifications.

BACKGROUND: Fully adapting a forward genetic approach to mammalian systems requires efficient methods to alter systematically gene products without prior knowledge of gene sequences, while allowing for the subsequent characterization of these alterations. Ideally, these methods would also allow function to be altered in a temporally controlled manner. RESULTS: We report the development of a miniaturized cell-based assay format that enables a genetic-like approach to understanding cellular pathways in mammalian systems using small molecules, rather than mutations, as the source of gene-product alterations. This whole-cell immunodetection assay can sensitively detect changes in specific cellular macromolecules in high-density arrays of mammalian cells. Furthermore, it is compatible with screening large numbers of small molecules in nanoliter to microliter culture volumes. We refer to this assay format as a 'cytoblot', and demonstrate the use of cytoblotting to monitor biosynthetic processes such as DNA synthesis, and post-translational processes such as acetylation and phosphorylation. Finally, we demonstrate the applicability of these assays to natural-product screening through the identification of marine sponge extracts exhibiting genotype-specific inhibition of 5-bromodeoxyuridine incorporation and suppression of the anti-proliferative effect of rapamycin. CONCLUSIONS: We show that cytoblots can be used for high-throughput screening of small molecules in cell-based assays. Together with small-molecule libraries, the cytoblot assay can be used to perform chemical genetic screens analogous to those used in classical genetics and thus should be applicable to understanding a wide variety of cellular processes, especially those involving post-transitional modifications.

Acetylation↗
PubMed1999

Homogeneous fluorescence readouts for miniaturized high-throughput screening: theory and practice.

It is widely recognized that fluorescence techniques represent the most important future detection method for miniaturized ultra-high-throughput screening. However, such techniques encompass many different approaches, each with its own particular set of advantages and limitations. Here, the authors summarize each of the major fluorescence techniques and explain the underlying principles that form the basis for a theory-led strategy to readout selection and assay design.

Journal Article↗
PubMed1999

Miniaturized FRET assays and microfluidics: key components for ultra-high-throughput screening.

Assay miniaturization applicable across a wide range of target classes, along with automation and process integration, are well-recognized goals for ultra-high-throughput screening on an industrial scale. This report summarizes the implementation of fluorescence resonance energy transfer (FRET)-based biochemical and cell-based assays in 3456-well NanoWelltrade mark assay plates using key components of Aurora's ultra-high-throughput screening system.

Journal Article↗
PubMed2003

A bead-alignment device with a bead-sized microchamber on a rotating cylinder for fabrication of a miniaturized probe array.

We have developed a compact bead-alignment device with a bead-sized microchamber on a rotating cylinder. The cylinder fits inside a tube with bead-stock pipes containing different probe-conjugated beads and holes for bead-alignment capillaries. The cylinder rotates in the tube, and the microchamber transfers a single 100-microm-diameter bead from a pipe to one of the capillaries in 10 s. By using this process repeatedly, 'bead arrays', which are miniaturized DNA probe arrays in capillaries, were successfully fabricated.

Journal Article↗