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At least 559 records · Page 31Linked to original sources
PubMed1987

Evaluation of bladder cancer with a miniature high frequency transurethral ultrasonography probe.

A miniature high frequency 10 MHz transurethral ultrasonography probe has been developed which is adaptable to any standard 17 F cystoscope sheath. High frequency contributed to a definite improvement in image resolution but did not allow distinct visualisation of different bladder wall layers. An 80% correlation between ultrasonographic and pathological staging was established after evaluation of 50 consecutive patients with newly diagnosed bladder tumours. Ta/T1 tumours tended to be overstaged with ultrasound. In some patients, the response to conservative treatment (external beam radiation therapy) of deeply infiltrating tumours could be assessed with the miniature probe on an out-patient basis.

Cystoscopy↗
PubMed1991

Cognitive processes among skilled miniature golf players: effects of instructions on motor performance, concentration time, and perceived difficulty.

Highly skilled miniature golf players were examined on a simplified miniature golf task under different instructional conditions. Results indicated that requirements to attend to a variety of technical aspects of the game during preparation impaired motor performance, whereas providing players with those aspects of the game they reported thinking of did not affect motor performance. Data on concentration time and perceived difficulty indicated that increasing cognitive demands were associated with a decline in motor precision. The overall pattern of results was interpreted such that attention directed at technical aspects of the game interfered with the players' normal cognitive activity. Susceptibility to interference is a characteristic feature of controlled cognitive operations. Thus, the present results are consistent with the view that conscious cognitive activity may support motor behavior also at late stages of skill development.

Adult↗
PubMed1999

Behaviour of NMDA and AMPA receptor-mediated miniature EPSCs at rat cortical neuron synapses identified by calcium imaging.

1. Simultaneous recording of intracellular calcium concentration at a synapse and synaptic currents from the cell body allows mapping of miniature excitatory postsynaptic currents (mEPSCs) to single synapses. 2. In the absence of extracellular Mg2+, 77 % of synapses had mEPSCs with fast and slow components, attributed to AMPA- and NMDA-type glutamate receptors, respectively. The remainder of synapses (23 %) had mEPSCs that lacked a fast component; these responses were attributed to NMDA receptors. 3. A strong positive correlation between the amplitude of the calcium transient and the NMDA receptor-mediated mEPSC was observed, indicating that the mEPSCs originate from an identified synapse. 4. At synapses that had both mEPSC components, the AMPA receptor component was positively correlated with charge influx mediated by NMDA receptors during repeated synaptic events. No periodic failure in the AMPA receptor mEPSC was observed at synapses expressing both receptor components. 5. A significant positive correlation between the mean amplitudes of NMDA and AMPA receptor components of mEPSCs is observed across different synapses. 6. We suggest that factors effecting both receptor classes, such as the amount of transmitter in synaptic vesicles, might contribute to the variation in mEPSC amplitude during repeated miniature events at a single synapse. Although the average postsynaptic response at different synapses can vary in amplitude, there appears to be a mechanism to keep the ratio of each receptor subtype within a narrow range.

Animals↗
PubMedDate not supplied

Skeletal atavism in a miniature horse.

An 8-month-old miniature horse filly was presented for evaluation of severe rotational and angular limb deformities of the thoracic and pelvic limbs. On radiographic examination, complete ulnas and fibulas were identified. These findings are consistent with a condition previously described as a form of atavism. The term atavism is used to describe the reappearance of a trait or character that was seen in all earlier evolutionary specimens of a particular species, but has not been seen in recent ancestors. The atavistic traits of complete ulnas and fibulas have previously been described in Welsh and Shetland Ponies, all of which had severe rotational and angular limb deformities. In this horse, bilateral osteochondritis dissecans of the medial trochlear ridge of the talii were also identified. To the authors' knowledge, this is the first report of the atavistic traits of complete ulnas and fibulas seen in the miniature horse.

Animals↗
PubMed1996

Pneumocystis carinii in the miniature dachshund: case report and literature review.

This article reviews Pneumocystis carinii and presents four cases in the miniature dachshund. The cases presented with hyperpnoea, tachypnoea and exercise intolerance. There were also clinical signs suggestive of immune incompetence in all the dogs. P carinii pneumonia was diagnosed in all four cases on transtracheal aspirate cytology. Immunological studies showed low globulin levels on serum electrophoresis, decreased lymphoblast transformation response (in the two cases that were tested) and a deficiency of immunoglobulins A, G and M. Light and electron microscopy as well as anti-canine immunoglobulin G immunoperoxidase staining studies were performed on one case which had died because of the disease. From these four cases, it appears that P carinii pneumonia in the miniature dachshund may be the result of an immunodeficiency. It does not, however, appear to be a classic primary severe combined immunodeficiency syndrome as the dogs appeared to respond to treatment, did not show growth failure and did not manifest overwhelming commensurate bacterial infections.

Animals↗
PubMed1999

Miniature EPSPs and sensory encoding in the primary afferents of the vestibular lagena of the toadfish, Opsanus tau.

The synaptic activity transmitted from vestibular hair cells of the lagena to primary afferent neurons was recorded in vitro using sharp, intracellular microelectrodes. At rest, the activity was composed of miniature excitatory postsynaptic potentials (mEPSPs) at frequencies from 5 to 20/s and action potentials (APs) at frequencies betwen 0 and 10/s. mEPSPs recorded from a single fiber displayed a large variability. For mEPSPs not triggering APs, amplitudes exhibited an average coefficient of variance (CV) of 0.323 and rise times an average CV of 0.516. APs were only triggered by mEPSPs with larger amplitudes (estimated 4-6 mV) and/or steeper maximum rate of rise (10.9 mV/ms, +/- 3.7 SD, n=4 experiments) compared to (3.50 mV/ms, +/-0.07 SD, n=6 experiments) for nontriggering mEPSPs. The smallest mEPSPs showed a fast rise time (0.99 ms between 10% and 90% of peak amplitude) and limited variability across fibers (CV:0.18) confirming that they were not attenuated signals, but rather represented single-transmitter discharges (TDs). The mEPSP amplitude and rise-time relationship suggests that many mEPSPs represented several, rather than a single pulse of secretion of TDs. According to the estimated overall TD frequency, the coincidence of TDs contributing to the same mEPSP were not statistically independent, indicating a positive interaction between TDs that is reminiscent of the way subminiature signals group to form miniature signals at the neuromuscular junction. Depending on the duration and intensity of efferent stimulation, a complete block of AP initiation occurred either immediately or after a delay of a few seconds. Efferent stimulation did not significantly change AP threshold level, but abruptly decreased mEPSP frequency to a near-complete block that followed the block of APs. Maximum mEPSP rate of rise decreased during, and recovered progressively after, efferent stimulation. After termination of efferent stimulation, mEPSP amplitude did not recover instantly and for a few seconds the amplitude distribution of synaptic events showed fewer large-amplitude events than during the control period. This confirms that mEPSP amplitude and rate of rise properties, which are critical for triggering afferent APs, are modified by efferent activity. The depression of afferent AP firing during efferent stimulation corresponded to a decrease in mEPSP frequency and, to a lesser extent, a decrease in mEPSP amplitude and rate of rise, suggesting, a decrease in the level of interaction among TDs contibuting to a mEPSP.

Action Potentials↗
PubMed2000

Surgical treatment of tarsometatarsal joint luxation in a miniature horse foal.

A 2-week-old Miniature Horse foal was referred for evaluation and treatment of a luxated right tarsometatarsal joint. Treatment consisted of closed reduction and internal fixation using two partially threaded Steinmann pins placed in normograde fashion through the tuber calcis into the proximal third metatarsus. Traumatic luxation has been reported to occur in the tarsocrural, proximal intertarsal and tarsometatarsal joints within the equine tarsus. Treatment for luxation of the distal intertarsal joint has not been documented. The treatment method most commonly suggested for tarsal luxation is closed reduction and cast immobilisation. Internal fixation using lag screws and plating has also been described. A combination of internal fixation and external coaptation is thought to achieve maximal stability and allow faster convalescence in cases of tarsal luxation. This case report describes for the first time a technique using two Steinmann pins to achieve successful internal fixation of a traumatic tarsometatarsal joint luxation in a 2-week-old Miniature Horse foal.

Animals↗
PubMed1988

Correction for sample free glycerol is needed for accurate measurement of plasma triglyceride concentrations in miniature Swine.

Methods for the measurement of plasma or serum triglyceride concentrations usually quantify the glycerol released by enzymatic hydrolysis of the triglyceride molecule. Any free glycerol in the sample is measured erroneously as triglyceride in these methods. As miniature swine have been used commonly for comparative studies of plasma lipoprotein lipids, this study was conducted to assess the need for free glycerol correction of plasma triglyceride measurements by comparing glycerol-blank corrected and non-corrected total plasma triglyceride concentrations from fasted minipigs. Fasting plasma free glycerol concentrations range from 9 to 14 mg/dl. The mean +/- SD (n = 16) glycerol-blank corrected total plasma triglyceride value (77 +/- 8 mg/dl) was significantly (p < 0.001) less than the uncorrected measurement value (189 +/- 12 mg/dl). Poor correlation (r = 0.24) between corrected and uncorrected total plasma triglyceride measurements suggests that mathematic correction by a constant correction factor would yield inaccurate results for miniature swine. Free glycerol blanking is essential for determination of the true total plasma triglyceride concentration.

Journal Article↗
PubMed1998

Hematologic values of the yucatan miniature pig.

Mean values and ranges for 16 hematological parameters for healthy, young, sexually-mature Yucatan miniature swine are presented. No significant differences were observed between sexes with regard to hemograms. Comparison of observed values with those published in the literature for standard domestic and other breeds of miniature swine reveals no major differences.

Journal Article↗
PubMed1969

Use of a miniature GM counter and a whole body counter in the study of potassium transport by the colon of normal, sodium-depleted and adrenalectomized rats in vivo.

1. A method is described employing a whole-body counter and a miniature GM counter placed within the lumen of the gut which can be used to study the absorption rates and kinetics of labelled substances in the mucosal epithelium in vivo. The method was applied to the study of K transport by the mucosa of the descending colon of normal, Na-depleted and adrenalectomized rats.2. The K influx rate was linearly related to luminal [K] over the range 5-80 mM. NaCN in the lumen produced a fall of electrical potential difference (p.d.) and of K secretion rate but did not reduce K influx rate. The findings were consistent with passive K influx.3. The mucosal (42)K content reached a steady value after 60-90 min of exposure to (42)K in the lumen. The value was similar in normal and adrenalectomized rats but was greater in Na-depleted rats.4. After replacement of luminal solution by a non-radioactive solution the fall of mucosal (42)K content could be described, in the majority, by a curve having two exponential components with half-times of 8-10 and 65-106 min. Approximately half of the (42)K outflow passed to the lumen. The rate constants were similar in all groups of rats.5. The results analysed on the basis of representing the mucosal K as in two compartments, indicated that the observed absorption rate could not be accounted for by transport through these compartments alone and that most of the (42)K crossed the mucosa by a fast pathway not detectable by the miniature GM counter. Most of the mucosal K was relatively inaccessible from the lumen.6. Na depletion raised the transmucosal p.d., increased the K secretion rate and appeared to increase K permeability of the mucosa but the kinetics were unaltered. Accumulation of (42)K in the mucosa was greater, suggesting that the permeability of the luminal face had increased. Adrenalectomy produced only one change, namely a reduction of K secretion rate.

Adrenalectomy↗
PubMed1972

Miniature end-plate currents and potentials generated by quanta of acetylcholine in glycerol-treated toad sartorius fibres.

1. Part of the end-plate region of glycerol-treated toad sartorius muscle fibres in a hypertonic solution was voltage-clamped using two microelectrodes. The control was adequate for recording miniature end-plate currents (m.e.p.c.s) in the vicinity of the electrodes only, at clamp potentials from - 20 to - 100 mV. At any potential, the peak amplitude of m.e.p.c.s varied widely but their mean amplitude was linearly related to clamp potential. The equilibrium potential, obtained by extrapolation, was more positive than in normal fibres.2. The growth phase of m.e.p.c.s was linear and rapid (< 0.7 msec). The decay phase was exponential. The time constant of decay of m.e.p.c.s was affected by temperature, and increased as the membrane potential was increased. At 20 degrees C, the time constant of decay ranged from 0.8 to 3.8 msec at membrane potentials from - 20 to - 100 mV.3. The mean conductance change caused by a quantum of acetylcholine was 5.5 x 10(-8) mho.4. Voltage responses to rectangular current injections through one electrode were recorded with three other electrodes in the end-plate region of glycerol-treated fibres. Miniature end-plate potentials (m.e.p.p.s) were also recorded with the same four electrodes.5. The decrement of both DC voltage responses and m.e.p.p.s along a fibre was exponential but the m.e.p.p. ;space constant' was significantly shorter than the DC space constant.

Acetylcholine↗
PubMed1987

Effect of chloride ions on giant miniature end-plate potentials at the frog neuromuscular junction.

1. Frog sartorius muscles were incubated in Ringer solutions with a raised K+ concentration (high K+) and then allowed to recover in medium with a normal K+ concentration. During the recovery period miniature end-plate potentials (m.e.p.p.s) were recorded with intracellular electrodes. In addition, the acetylcholine (ACh) released from muscles in the presence of high K+ was measured by a mass spectrometric method. 2. Incubation in a high-K+ medium induced the appearance of giant miniature end-plate potentials (g.m.e.p.p.s). However, if the Cl- of the medium was substituted by propionate, very few g.m.e.p.p.s were observed. This was due to the absence of Cl- and not to the presence of propionate. The frequency of g.m.e.p.p.s was also greatly depressed when the Cl- concentration was lowered from 120 to 60 mM. 3. The amount of ACh released into a high-K+ medium was the same, regardless of whether Cl- or propionate was the anion. 4. When Cl- was replaced by NO3- or Br-, incubation in high-K+ Ringer solution induced the appearance of g.m.e.p.p.s. However, SO4(2-), like propionate, was unable to substitute for Cl- in this respect. 5. The frequency of g.m.e.p.p.s was correlated with that of m.e.p.p.s during the recovery period. However, when the K+ concentration was raised to 17 mM the frequency of m.e.p.p.s greatly increased, whereas that of the g.m.e.p.p.s did not change significantly. 6. G.m.e.p.p.s disappeared in the presence of curare, but persisted in the presence of tetrodotoxin or in a Ca2+-lacking medium. However, g.m.e.p.p.s failed to appear when the medium had lacked Ca2+ during the stimulation. 7. It is tentatively concluded that g.m.e.p.p.s are associated with Cl--dependent processes which occur after stimulation of transmitter release, and which are linked with the endocytotic retrieval of presynaptic membrane.

Acetylcholine↗
PubMed2003

Miniature synaptic transmission and BDNF modulate dendritic spine growth and form in rat CA1 neurones.

The refinement and plasticity of neuronal connections require synaptic activity and neurotrophin signalling; their specific contributions and interplay are, however, poorly understood. We show here that brain-derived neurotrophic factor (BDNF) increased spine density in apical dendrites of CA1 pyramidal neurones in organotypic slice cultures prepared from postnatal rat hippocampal slices. This effect was observed also in the absence of action potentials, and even when miniature synaptic transmission was inhibited with botulinum neurotoxin C (BoNT/C). There were, however, marked differences in the morphology of individual spines induced by BDNF across these different levels of spontaneous ongoing synaptic activity. During both normal synaptic transmission, and when action potentials were blocked with TTX, BDNF increased the proportion of stubby, type-I spines. However, when SNARE-dependent vesicular release was inhibited with BoNT/C, BDNF increased the proportion of thin, type-III spines. Our results indicate that BDNF increases spine density irrespective of the levels of synaptic transmission. In addition, miniature synaptic transmission provides sufficient activity for the functional translation of BDNF-triggered spinogenesis into clearly defined morphological spine types, favouring those spines potentially responsible for coordinated Ca2+ transients thought to mediate synaptic plasticity. We propose that BDNF/TrkB signalling represents a mechanism of expression of both morphological and physiological homeostatic plasticity in the hippocampus, leading to a more efficient synaptic information transfer across widespread levels of synaptic activity.

Action Potentials↗
PubMed1999

Miniature scintillating detector for small field radiation therapy.

In planning stereotactic radiosurgery treatments, depth dose curves, profiles, and dose rate of treatment beams are difficult to obtain with conventional detectors because of loss of lateral electronic equilibrium and volume averaging. A scintillating detector with high spatial resolution and good reliability has been developed to overcome this problem. The miniature dosimeter consists of two identical radiation-resistant 10 m long silica optical fibers, each connected to an independent silicon photodiode. A small cylindrical polystyrene scintillator (3.9 mm3) is optically glued to the detection fiber. The light seen by the photodiode connected to this fiber arises from fluorescence of the scintillator and from the Cerenkov effect produced in silica. The reference signal produced by the fiber without scintillator is used to subtract the Cerenkov light contribution from the raw detector response. The sensitive volume of the scintillating detector is nearly water-equivalent and thus minimizes dose distribution perturbation in water. The miniature dosimeter has a spatial resolution comparable to the film-densitometer system. Profiles of 1 cm diam, 6 MV photon beam measured with both systems show very similar shapes. Furthermore, the use of photodiodes instead of photomultiplier tubes gives a better stability response and offers the possibility to perform absolute dosimetry.

Gamma Cameras↗
PubMed2004

Regulation of dendritic protein synthesis by miniature synaptic events.

We examined dendritic protein synthesis after a prolonged blockade of action potentials alone and after a blockade of both action potentials and miniature excitatory synaptic events (minis). Relative to controls, dendrites exposed to a prolonged blockade of action potentials showed diminished protein synthesis. Dendrites in which both action potentials and minis were blocked showed enhanced protein synthesis, suggesting that minis inhibit dendritic translation. When minis were acutely blocked or stimulated, an immediate increase or decrease, respectively, in dendritic translation was observed. Taken together, these results reveal a role for miniature synaptic events in the acute regulation of dendritic protein synthesis in neurons.

Action Potentials↗
PubMed2003

Miniature transmitter release: accident of nature or careful design?

Miniature transmitter release results from the constitutive low-level release of individual vesicles of neurotransmitter. Since the 1950s, this form of synaptic transmission has largely been thought to reflect a leaky evoked-release mechanism, and it was not clear whether it had a function of its own. Recent data challenge this view and suggest that miniature release can affect both the local chemistry of synapses and the network properties of neurons.

Animals↗
PubMed2006

Use of miniaturized protein arrays for Escherichia coli O serotyping.

Serological typing of Escherichia coli O antigens is a well-established method used for differentiation and identification of O serotypes commonly associated with disease. In this feasibility study, we have developed a novel somatic antibody-based miniaturized microarray chip, using 17 antisera, which can be used to detect bound whole-cell E. coli antigen with its corresponding immobilized antibody, to assess the feasibility of this approach. The chip was tested using the related 17 control strains, and the O types found by the microarray chip showed 100% correlation with the O types found by conventional typing. A blind trial was performed in which 100 E. coli isolates that had been O serotyped previously by the conventional assay were tested by the array approach. Overall, the O serotypes of 88% of isolates were correctly identified by the microarray method. For several isolates, ambiguity of O-type designation by microarray arose due to increased sensitivity of this method, allowing signal intensities of cross-reactions to be quantified. Investigation of discrepancies between conventional and microarray O serotyping indicated that some isolates upon storage had become untypeable and, therefore, gave poor signal intensity when tested by the microarray or retested by conventional means. For all 20 serotype O26 and O157 isolates, the apparent discrepancy in O serotyping was analyzed further by a third independent test, which confirmed the microarray results. Therefore, the use of miniaturized protein arrays increases the speed and efficiency of O serotyping in a cost-effective manner, and these preliminary findings suggest the microarray approach may have a higher accuracy than those of traditional O-serotyping methods.

Antigens, Bacterial↗
PubMed2003

Asymmetrical distribution of Neisseria miniature insertion sequence DNA repeats among pathogenic and nonpathogenic Neisseria strains.

Neisseria miniature insertion sequences (nemis) are miniature DNA insertion sequences found in Neisseria species. Out of 57 elements closely flanking cellular genes analyzed by PCR, most were conserved in Neisseria meningitidis but not in N. lactamica strains. Since mRNAs spanning nemis are processed by RNase III at hairpins formed by element termini, gene sets could selectively be regulated in meningococci at the posttranscriptional level.

DNA Transposable Elements↗