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 469 records · Page 26Linked to original sources
PubMed2005

Effects of cholinergic receptor agonists and antagonists on miniature stimulatory postsynaptic ionic currents in somatic muscle cells of lumbricus terrestris.

Miniature stimulating postsynaptic currents of Lumbricus terrestris somatic muscle cells were recorded. Atropine, d-tubocurarin, alpha-bungarotoxin, carbacholine, and proserin did not modify the amplitude and temporal parameters of miniature stimulatory postsynaptic currents, while carbacholine and nicotine depolarized the muscle membrane. Presumably, Lumbricus terrestris muscle cells contain acetylcholine-sensitive channel-receptor complexes not belonging to classical nicotinic or muscarinic acetylcholine receptors.

Animals↗
PubMed1984

Method for intraoperative assessment of organ perfusion and viability using a miniature oxygen sensor.

A specially designed miniaturized Clark polarographic electrode was used to measure organ surface oxygen tension during surgical operations in 10 patients as a means of determining tissue perfusion and viability. When applied to organ surfaces, the sensor noninvasively provides real-time assessment of tissue PO2. Values obtained are dependent on both arterial PO2 and local blood flow and therefore may be used to quantitatively assess local oxygen delivery (perfusion). Measured values may be compared with arterial PO2 or to areas of certain normal perfusion on the same organ to better define the adequacy of local oxygen transport. Tissue temperature is independently measured and may be used to assess the metabolic activity of the tissue monitored. Organ surface oximetry using the miniature PO2 sensor is a practical and repeatable method for the intraoperative assessment of organ perfusion and viability.

Adenocarcinoma↗
PubMed1980

Alterations in spontaneous miniature potential activity during habituation of a vertebrate monosynaptic pathway.

Intracellular recordings of spontaneous miniature synaptic potentials were made from motoneurons of the isolated spinal cord of the frog, as a function of habituation of the monosynaptic pathway originating with lateral column fibers. The frequency and amplitude of spontaneous miniature potentials were used to assess the possibility of several proposed mechanisms underlying habituation in this system. These studies provide clear evidence in eliminating the role of transmitter depletion, incomplete vesicle filling and receptor desensitization in the habituation process occurring within this vertebrate central nervous system.

Animals↗
PubMed1984

The effect of temperature on the growth and decay times of miniature end-plate currents in the mouse diaphragm.

The temperature dependence of both the growth and the decay phases of miniature end-plate currents was investigated in the mouse diaphragm. The relationship between the log of the time constant of decay and reciprocal temperature was linear, that between the growth phase duration and temperature was not linear, the Q10 being higher over the low end of the temperature range. The possible reasons for the non-uniform Q10 of the growth time of the miniature end-plate current are discussed.

Animals↗
PubMed1987

Spontaneous miniature outward currents in cultured bullfrog neurons.

Spontaneous miniature hyperpolarizations were observed in cultured bullfrog neurons. Depolarization increased the frequency and amplitude of the events. Under voltage-clamp, these events were manifested as spontaneous miniature outward currents of SMOCs which were usually less than 2 nA, had a rapid rising phase and a slower voltage-dependent exponential decay. Analysis of inter-event intervals suggested that SMOCs occurred randomly, while analysis of their amplitudes yielded exponential amplitude distributions. Mean SMOC amplitudes and SMOC frequency increased with depolarization, even with 100 microM CdCl2 present. Time constants of SMOC decay resembled time constants obtained from voltage-jump experiments on Ca2+-loaded cells, and together with the sensitivity of SMOCs to tetraethyl ammonium (TEA), suggested that SMOCs are due to activation of fast Ca2+-gated potassium channels. We propose that a SMOC occurs when 10-5000 of these channels are activated by punctate intracellular Ca2+ release.

Animals↗
PubMed1992

Spontaneous miniature hyperpolarizations of presynaptic nerve terminals in the chick ciliary ganglion.

Intracellular recordings from presynaptic nerve terminals in the chick ciliary ganglion revealed the presence of spontaneous miniature hyperpolarizations in virtually all (approximately 86%) nerve terminals examined. These spontaneous events appeared as small, brief hyperpolarizations at resting potential and were observed to increase or decrease as the membrane potential was depolarized or hyperpolarized from rest, respectively. The hyperpolarizing potentials were sensitive to blockade by tetraethylammonium and Ba2+, while caffeine increased then abolished these events. The voltage fluctuations were unaffected by tetrodotoxin, low Ca2+ external solution or the synaptic blockers, picrotoxin and strychnine. These spontaneous, transient, miniature hyperpolarizations may be due to the brief and co-ordinated activation of between 15-60 Ca(2+)-dependent K+ channels following the release of Ca2+ from internal stores.

Animals↗
PubMed1990

Metabolic labeling of rod outer segment phospholipids in miniature poodles with progressive rod-cone degeneration (prcd).

The recessive genetic defect in miniature poodles which results in progressive rod-cone degeneration (prcd) has been investigated in an attempt to determine the biochemical abnormality involved. In the present study, the rod outer segments of young prcd affected miniature poodles and normal dogs have been compared with respect to the incorporation of intravitreally injected [3H]palmitic acid. [14C]linolenic acid, and [14C]docosahexaenoic acid into neutral lipids and phospholipids as well as [3H]palmitate and [14C]leucine into rhodopsin. In addition, 3 mm trephined punches of retinas were incubated with [3H]palmitic acid, [3H]arachidonic acid, [14C]linolenic acid, [3H]serine, [14C]glycerol and [14C]leucine. No difference in incorporation of labeled precursors into lipids or rhodospin was noted between prcd affected and normal retinas. Phosphatidyl choline appeared to function as a carrier of fatty acids to the rod outer segment where they were redistributed to other phospholipids. An interesting lack of conversion of the essential fatty acid linolenic acid to docosahexaenoic acid was noted in both normal and affected retinas. This conversion involves elongation and desaturation of linolenic acid and may take place primarily in extraretinal tissues such as the liver. This finding, in conjunction with a parallel study of plasma fatty acids which has shown significantly lower levels of docosahexaenoic acid in prcd affected poodles, points to a possible systemic defect in the metabolism or transport of docosahexaenoic acid, a fatty acid uniquely enriched in the photoreceptor outer segments.

Animals↗
PubMed1982

Yucatan miniature swine as a model for diet-induced atherosclerosis.

Nine female Yucatan miniature swine, a breed not previously evaluated for their potential usefulness as a model for experimental atherosclerosis studies, were fed a high-fat, high-cholesterol diet for 10-12 months. These swine and 4 control (low-fat, low-cholesterol-fed) swine underwent a complete necropsy at the end of this period to characterize the atherosclerosis both by gross and microscopic examination. Cholesterol feeding led to elevated serum cholesterol levels and the development of accelerated atherosclerosis. Control animals on a low-cholesterol diet had little gross or microscopic atherosclerosis. All of the cholesterol-fed swine had more extensive atherosclerosis than any of the controls by gross inspection of the Sudan-stained arterial tissue. There was individual variation suggesting the interaction of factors in addition to the plasma cholesterol which determine the extent and severity of atherosclerosis. However, it was possible to show a positive correlation between hypercholesterolemia and (1) intimal thickening in the terminal abdominal aorta and mesenteric artery, and (2) increased fat deposition in the mesenteric artery. The cholesterol-induced atherosclerosis was characterized by the deposition of lipid in and around cells. Complicated atherosclerotic lesions similar to human atherosclerosis were characterized by marked animal proliferation, necrosis, cholesterol crystal deposition, and calcification. It is concluded that the Yucatan miniature swine represent an important additional animal model in which to study certain aspects of atherosclerosis.

Animals↗
PubMed1995

In vitro development of embryos from Sinclair miniature pigs: a preliminary report.

The goal of this project was to identify conditions that result in development from the zygote or the 2-cell stage Sinclair miniature pig embryos to the blastocyst stage. Four media were selected, 2 that have been shown to result in in vitro development in domestic pigs (Hepes buffered Tyrode's medium and Whitten's medium), 1 that is compatible with similar development in the cow (CR-1), and 1 that is compatible with development in the mouse (CZB). One- and two-cell stage embryos from Sinclair miniature pigs were flushed from oviducts in Hepes buffered Tyrode's medium, allocated to 1 of the 4 media and cultured for 120 h. At the end of the culture period, embryos were morphologically scored and nuclei were counted. Morphology scores were lowest for Hepes buffered Tyrode's medium but were not different for Whitten's medium, CZB or CR-1. The highest (P < 0.07) number of nuclei was present in the oocytes cultured in Whitten's medium (21.3), with CR-1 (15.7) and CZB (16.5) not differing significantly. Similar to the morphology scores, Hepes buffered Tyrode's medium resulted in the lowest number nuclei (5.5). In a parallel experiment, domestic pig embryos were cultured in Hepes buffered Tyrode's medium versus Whitten's medium. The domestic pig embryos, while also developing better in Whitten's Medium, developed better in the Hepes buffered Tyrode's medium than did the embryos from Sinclair pigs. Thus, the Sinclair pig embryo develops best if placed in Whitten's Medium.

Journal Article↗
PubMed1981

Effects of prostaglandin inhibition on renal function in deoxycorticosterone-acetate hypertensive Yucatan miniature swine.

This study evaluated the effect of prostaglandin (PG) on renal function in normal and deoxycorticosterone-acetate (DOCA) hypertensive Yucatan miniature swine. Eight animals were implanted with DOCA impregnated silicone strips. MAP increased in the conscious DOCA animals from a normal pressure of 110-115 mmHg, to 148 +/- 4 mmHg. After 3-4 weeks, the DOCA hypertensive and eight normal (sham or non-implanted) animals were anesthetized with sodium pentobarbital which reduced MAP in the DOCA pigs to normotensive levels. Under anesthesia, PG inhibition (indomethacin or meclofenamate, 2 mg/kg i.v.) increased MAP only in the normal group (P less than .05). PG inhibition caused a significant reduction in renal blood flow in both groups, but only decreased glomerular filtration rate in the DOCA animals (P less than .05). Radioactive microsphere distribution to the other cortex of the normal animals was significantly decreased with PG inhibition, (P less than .05). No consistent changes in electrolyte excretion or urine flow rate was seen in either group following PG inhibition. These data indicate that PG may influence renal hemodynamics in both normal and DOCA hypertensive Yucatan miniature swine. The finding that PG inhibition selectively decreases GFR in the DOCA animals suggests a possible protective role of these hormones in this hypertensive animal model.

Animals↗
PubMed1991

Miniature manipulator with microelectrode for chronic recording of single units from freely-moving animals.

We report a simple recording and stimulating system, a miniature manipulator with a microelectrode (MMM) that can be mounted on animal's skull. The system consists of a miniature manipulator and a microelectrode which are used in one body. Several MMMs can be implanted simultaneously into the brain as the part of the manipulator is small. With this device, recording of single units from several different cortices is possible from awake and unrestricted animals.

Animals↗
PubMed1979

Gas exchange, pulmonary mechanics and haemodynamics in adult respiratory distress syndrome: experimental results in Lewe miniature pigs.

Adult respiratory distress syndrome (ARDS) is a common medical emergency in respiratory care complicating a great variety of traumas and diseases. An animal model from Lewe miniature pigs has been developed to study the ARDS under standardized conditions; it is based on aspiration pneumonitis, a disorder often observed in ARDS, injuring the lung alveolar surfactant system. The experimental study was conducted under neuroleptanalgesia. ARDS was produced by intratracheal application of hydrochloric acid (0.2 mol/l) in an amount of 1.0 ml/kg body wt. The animals were ventilated automatically by a standardized ventilatory pattern in IPP mode. In all animals the time course of oxygenation ratio (Pa,O2/F1O2), arterial CO2 tension (Pa,CO2), ratio of alveolo--arterial oxygen tension difference to inspired oxygen fraction (Aa,DO2/F1O2), oxygen exchange ratio ((AaDO2/Pa,O2), lung compliance (CL), inspiratory airway resistance (RrsI), dead space ratio VD/VT), pulmonary artery pressure (PAP) and systemic blood pressure were studied. Changes in quasi-static volume--pressure curves, percentage change in lung water content and gross pathological finding were used to integrate the findings into a system of pathophysiological changes in ARDS. The animal group to which hydrochloric acid was administered shows severe pulmonary distress leading to death within 3.5--7.5 h. No significant changes in the measured parameters could be observed in the control group over a 14 h period. The results suggest that aspiration pneumonitis in Lewe miniature pigs is very suitable to investigate various problems in pathogenesis of ARDS. The model provides reproducible results which correlate very well with findings in different ARDS states. The models serves both to compare clinical states and to search for newer therapeutic manoeuvres.

Animals↗
PubMed1982

Ventilatory and circulatory O2 convection and blood acid-base changes in normoxic and hypoxic awake miniature swine.

1. Awake miniature swine were studied at rest and at neutral temperature while breathing either normoxic or hypoxic gas mixtures, PIO2 = 145 and 82 Torr, at low altitude. 2. Steady-state pulmonary ventilation (Vg) and breathing pattern (VT, fR), oxygen consumption (MO2), O2 concentrations (C) and pressures (P) in the arterial (a) and mixed venous blood (v), hematocrit (Ht) and acid-base status in arterial blood, heart frequency (fH) and systemic and pulmonary arterial pressures were measured. 3. From these data cardiac output (Vb) and stroke volume (Vs), ventilatory and circulatory requirements (Vg/MO2, Vb/MO2), extraction of O2 from inspired gas (EgO2) and blood (EbO2), capacitance coefficient of blood for oxygen (beta bO2), and the various oxygen conductances (GO2) from inspired air to mixed venous blood were calculated. 4. The miniature swine exhibited classical ventilatory and circulatory responses to hypoxia, although their ventilatory frequency was relatively low and the values of PCO2 and HCO3- concentration in the arterial were blood higher than in other mammals.

Acid-Base Equilibrium↗
PubMed1984

Giant inhibitory miniature currents in crayfish muscle in the presence and absence of extracellular sodium and serotonin.

At opener muscles of the claw, or first walking leg of small crayfish, giant spontaneous inhibitory postsynaptic currents (gsIPSCs) were recorded. In some experiments, the rate by which they occurred could be enhanced by application of 1 mumol/l serotonin (5-HT). The largest gsIPSCs seen were at least up to ten-fold larger than normal inhibitory miniature currents. Picrotoxin (10 mumol/l) reversibly abolished the gsIPSCs. Tetrodotoxin (0.1 mumol/l) or withdrawal of Na+ from the superfusion did not abolish gsIPSCs. Decay time constants of gsIPSCs, tau(gsIPSCs), were about two-fold larger than those of nerve evoked IPSCs and of normal inhibitory miniature currents. In Na+-free superfusion tau(gsIPSCs) was larger by a factor of about 1.8 than in normal superfusion, which might be a result of inhibition of a Na+-dependent transport process for inhibitory transmitter by removal of Na+ from the incubation medium.

Animals↗
PubMed1992

Presynaptic inhibition of miniature excitatory synaptic currents by baclofen and adenosine in the hippocampus.

Presynaptic inhibition of neurotransmitter release is thought to be mediated by a reduction of axon terminal Ca2+ current. We have compared the actions of several known inhibitors of evoked glutamate release with the actions of the Ca2+ channel antagonist Cd2+ on action potential-independent synaptic currents recorded from CA3 neurons in hippocampal slice cultures. Baclofen and adenosine decreased the frequency of miniature excitatory postsynaptic currents (mEPSCs) without affecting the distribution of their amplitudes. Cd2+ blocked evoked synaptic transmission, but had no effect on the frequency or amplitude of either mEPSCs or inhibitory postsynaptic currents (IPSCs). Inhibition of presynaptic Ca2+ current therefore appears not to be required for the inhibition of glutamate release by adenosine and baclofen. Baclofen had no effect on the frequency of miniature IPSCs, indicating that gamma-aminobutyric acid B-type receptors exert distinct presynaptic actions at excitatory and inhibitory synapses.

2-Amino-5-phosphonovalerate↗
PubMed1995

Mapping miniature synaptic currents to single synapses using calcium imaging reveals heterogeneity in postsynaptic output.

The amplitudes and kinetics of miniature excitatory synaptic currents (MESCs) in mammalian central neurons vary widely. It is unclear whether this variability occurs at each synapse or arises from differences among a heterogeneous population of synapses. Furthermore, it is not known how variability in these currents would affect their associated postsynaptic Ca2+ transients. To address these questions, we conducted simultaneous Ca2+ imaging and patch-clamp recordings from cultured cortical neurons and mapped individual MESCs to identified synapses displaying coincident dendritic miniature synaptic Ca2+ transients (MSCTs). Measurements of MSCTs at dendritic sites that displayed multiple events revealed that MSCT amplitude varied considerably at each site. Simultaneous measurement of MESCs and MSCTs at these sites indicated that variability in coincident synaptic currents contributes to the differences in Ca2+ transient amplitude. The ability of single synapses to exhibit variable output may enable them to engage intracellular signaling pathways at different levels of intracellular Ca2+.

Animals↗
PubMed1992

Mass miniature X-ray screening for tuberculosis among immigrants entering Switzerland.

Among 50,784 new immigrants entering Vaud Country, Switzerland, between 1988 and 1990, 674 abnormalities were discovered by mass miniature X-ray screening on arrival (424/43,803 foreign workers, 238/4512 refugees and 12/2469 foreign students). 2043 refugees had no radiological examination. After clinical examination, tuberculosis (TB) was considered the likely diagnosis in 256 cases, of which 132 were offered an antituberculous treatment according to the current recommendations of the Swiss Association against TB. 34 of the subjects were smear- or culture-positive (5% of all radiological abnormalities, 0.08% of all immigrants). Only 46 subjects had any clinical complaint. Among foreign workers, 0.18% were carriers of tuberculous lesions needing a treatment; the proportion was 1.22% among refugees. By ethnic origin, the proportion is highest among Africans (1.43%), followed by Turks (1.04%), subjects from the Middle East (0.62%), Yugoslavia (0.55%), Portugal and Spain (0.14%). Mass miniature X-ray screening for TB in immigrants from high prevalence countries entering Switzerland still detects a majority of asymptomatic cases and seems an easy means of preventing the transmission of TB to members of the same community.

Emigration and Immigration↗
PubMed1995

Hepatic function during prolonged isolated rat liver perfusion using a new miniaturized perfusion circuit.

Previous designs of isolated rat liver perfusion circuits used for toxicological investigations are often expensive, cumbersome, or traumatic in relation to hepatic biocompatibility following extended perfusion times. A new, miniaturized circuit that incorporates a novel design of organ bath, to maintain a buoyant preparation, and a high-efficiency miniaturized membrane tubing oxygenator is described. Livers from male Sprague-Dawley rats were perfused continuously for 6 hr in vitro using rat blood diluted to a perfusate hematocrit of 9.75 +/- 0.35% with Krebs-Henseleit buffer (KHB). Hepatic function was evaluated by measurement of perfusion pressure, flow rate, bile volume production, bile bilirubin content, hepatic oxygen uptake (HOU), bromosulphthalein (BSP) removal, hepatic enzyme activities, and electrolyte concentrations, and finally by histological examination. Perfusion pressure and flow rate remained stable at 8.7 +/- 1.7 mmHg and 1.92 +/- 0.06 mL min-1 g-1 liver, respectively. Bile volume production and HOU were maximal at 784 +/- 84 microL h-1 and 0.99 micromol/L min-1 g-1 respectively. Erythrocyte damage in the perfusate was evaluated by measurement of reduction in perfusate hematocrit from 9.75 +/- 0.35% to 9.27 +/- 0.24%, and increases in plasma free hemoglobin, which rose from 85.8 +/- 12.3 mg% to 650.1 +/- 53.3 mg% over the 6-hr perfusion period studied. Using bile volume production, hepatic oxygen uptake, and the liberation of plasma free hemoglobin as the most sensitive indices of adverse conditions, the new circuit was capable of supporting an isolated perfused rat liver for periods of up to 6 hr under close-to-physiological conditions.

Animals↗