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PubMed1992

Multisection FLASH: method for breath-hold MR imaging of the entire liver.

One hundred ten patients with various focal liver lesions were imaged with a multisection fast low-angle shot (FLASH) gradient-echo sequence with an echo time of 4.6 msec. This sequence enabled the acquisition of 19 T1-weighted magnetic resonance (MR) images of the liver within a single 26-second breath hold. Patients were also examined with standard T1- and T2-weighted spin-echo (SE) sequences. The multisection FLASH sequence provided significantly higher (P less than .01) liver-spleen contrast, liver-spleen signal-difference-to-noise ratio (SD/N), liver-tumor contrast, and liver-tumor SD/N than the T1-weighted SE sequence but lower values than the T2-weighted SE sequence. Motion artifacts were reduced with the multisection FLASH sequence compared with both SE sequences (P less than .01). The overall image quality of the multisection FLASH images was similar to that of the T1-weighted SE images and superior to that of T2-weighted SE images. The most important characteristics of the multisection FLASH technique in MR imaging of the liver are the high T1 contrast, the prevention of motion artifacts, and a dramatic reduction in imaging time.

Adult↗
PubMed1993

Redundant use of luminance and flashing with shape and color as highlighting codes in symbolic displays.

Three visual search experiments evaluated the benefits and distracting effects of using luminance and flashing to highlight subclasses of symbols coded by shape and color. Each of three general shape/color classes (circular/blue, diamond/red, square/yellow) was divided into three subclasses by presenting the upper half, lower half, or entire symbol. Increasing the luminance of a subclass by a factor of two did not result in a significant improvement in search performance. Flashing a subclass at a rate of 3 Hz resulted in a significantly shorter mean search time (48% improvement). Increasing the luminance of one subclass (by a factor of five) while simultaneously flashing another significantly improved search times by 31% and 43% respectively, compared with nonhighlighted search conditions. In each experiment, the search times for nonhighlighted target subclasses were not affected by the presence of brighter and flashing targets. The failure of the initial experiment to find a significant performance improvement caused by increasing symbol luminance suggested that a larger luminance increase was necessary for this code to be effective. The overall results suggest that using luminance and flashing to highlight subclasses of color- and shape-coded symbols can reduce search times for these subclasses without producing a distraction effect by way of a concomitant increase in the search times for unhighlighted symbols.

Adult↗
PubMed1996

3DFT-flash MR imaging of pancreatic cancer with gadopentetate dimeglumine.

PURPOSE: We evaluated the usefulness of dynamic 3-dimensional Fourier transformation (3DFT) fast low angle shot (FLASH) MR imaging using gadopentetate dimeglumine (Gd-DTPA) to assess the extent of pancreatic cancer. MATERIAL AND METHODS: Breath-hold 3DFT-FLASH MR images (20/4; 25 degrees flip angle; 7 partitions; 3-5-mm slice thickness) were obtained before the ++administration of 0.1 mmol/kg of Gd-DTPA, just after (early phase), and 1 and 2 min (late phases) after in 14 patients with pancreatic cancer. All patients underwent surgical removal or laparotomy. We compared the findings of T1-, T2-, and postcontrast T1-weighted spin-echo (conventional SE) and 3DFT-FLASH imaging with histologic or surgical findings. RESULTS: Dynamic MR images could delineate the pancreatic tumors more clearly than the conventional SE images, and were useful for diagnosing vessel invasion. The contrast-to-noise ratio between the pancreatic cancer and the surrounding pancreatic parenchyma was significantly higher with the dynamic 3DFT-FLASH image than with the conventional SE images (p<0.01). CONCLUSION: Dynamic 3DFT-FLASH MR imaging with Gd-DTPA is useful in delineating and evaluating the extent of pancreatic cancer.

Adult↗
PubMed1994

Transdermal clonidine for ameliorating tamoxifen-induced hot flashes.

PURPOSE: To determine the efficacy of transdermal clonidine for alleviating tamoxifen-induced hot flashes in women with a history of breast cancer. PATIENTS AND METHODS: A randomized, double-blind, crossover design was used in this prospective study. Women with a history of breast cancer who were receiving tamoxifen and suffering from hot flashes were potentially eligible for this protocol study. RESULTS: Clonidine did reduce hot-flash frequency to a degree that was statistically impressive (P < .0001), but clinically moderate (20% reduction from baseline). It also decreased hot-flash severity (P = .02, 10% reduction from baseline). Clonidine was related to increased mouth dryness (P < .001), constipation (P < .02), itchiness under the patch (P < .01), and drowsiness (P < .05). CONCLUSION: Better means are needed to alleviate hot flashes among patients in whom estrogen therapy is contraindicated.

Administration, Cutaneous↗
PubMed1984

The effects of naloxone on hot flashes and gonadotropin secretion in postmenopausal women.

Hot flashes have a close temporal relationship with the initiation of LH pulses, suggesting that factors stimulating gonadotropin release are involved in the mechanism of this disturbance. It has been reported that the opiate antagonist naloxone acutely blocked subjective hot flashes, a seemingly paradoxical effect, since the use of this agent in premenopausal women increases the magnitude and frequency of LH pulses. We, therefore, studied the effects of naloxone in 16 postmenopausal women with frequent hot flashes using continuous recordings of finger temperature and skin resistance as objective indices of flushing and perspiration, respectively. After baseline recordings, the subjects were randomized into equal groups, and the recordings were repeated during 8-h infusion of either saline or naloxone (22 micrograms/min). Serum gonadotropin levels were measured at 15-min intervals before and during the last 4 h of the infusion. Naloxone did not change the rate of objectively measured hot flashes, mean serum LH or FSH levels, or the frequencies or amplitudes of gonadotropin pulses. These data suggest that there is a very low input of endogenous opiates on gonadotropin secretion in postmenopausal women and that opioid peptides do not play a role in the initiation of the postmenopausal hot flash.

Aged↗
PubMed2006

Effect of flashing light from blue light emitting diodes on cell growth and astaxanthin production of Haematococcus pluvialis.

To conserve energy in the production of astaxanthin by the green alga Haematococcus pluvialis, we utilized intermittent flashing light from blue light emitting diodes (LEDs) and investigated the effects of the incident light intensity (2-12 micromol m(-2) s(-1)), duty cycle (17-67%) and frequency (25-200 Hz) of flashing on the cell growth and astaxanthin production. In the above ranges, the final astaxanthin concentration under illumination by flashing light was significantly higher than that obtained under illumination with continuous light at the same incident intensity. For example, flashing light at an incident intensity of 8 micromol m(-2) s(-1) gave the same final astaxanthin concentration that was obtained under continuous light illumination at 12 micromol m(-2) s(-1), thus reducing energy consumption by 1/3. We therefore conclude that flashing light from blue LEDs is a promising illumination method for indoor algal cultivation using photobioreactors.

Bioreactors↗
PubMed2005

Topographic analysis of flash visual evoked potentials in dogs.

Visual evoked potentials by flash stimulation (flash VEP) were analyzed in dogs using a topographic method. The flash VEP consisted of 3 positive (P1, P2 and P3) and 2 negative (N1 and N2) components by 150 msec after the flash stimuli. On the topographic mappings, a negative response area was observed in the frontal region of the scalp in the stimulated site followed by the shifting of the area to the contralateral frontal region and occipital region, during the first 100 msec. The negative response area in the frontal region in the stimulated site, contralateral frontal and temporal region, and occipital region were corresponded to N1, P2, and N2 on the flash VEP, respectively, according to their latencies. In the dogs with experimentally impaired the right lateral geniculate body, the latency of P2 was prolonged, and N2 and P3 were disappeared after the left eye stimulation. On the topographic mapping, only the early negative response area was detected on the stimulated site of the frontal region of the brain. Therefore, it is concluded that P1 and N1, P2, and N2 are referred to the retinal potentials, the potentials from the retina to the brainstem included the lateral geniculate body, and those from the brainstem to the visual cortex, respectively.

Animals↗
PubMed1985

"Flash for life": Community-based prompting for safety belt promotion.

A community-based strategy for promoting safety belt use was field-tested in two adjacent rural communities, one populated by a preponderance of students, faculty, and staff of a major university. The intervention involved the front-seat passenger of a stopped vehicle displaying to the driver of an adjacent, stopped vehicle an 11 x 14 inch flash card that read, "PLEASE BUCKLE UP-I CARE." If the driver buckled up, the "flasher" flipped over the card and displayed the message, "THANK YOU." This flash card was shown to 1,087 unbuckled drivers; 82% of these drivers looked at the flash card and 22% of these complied with the buckle-up request. Compliance was not influenced by the age or gender of the "flasher" (young child vs. college student), nor by the gender of the driver; but significantly more drivers in the university town buckled up following the flash card presentation (25% mean compliance in the college town vs. 14% in the other community). To date, over 2,000 individuals have received a buckle-up flash card for their own use.

Journal Article↗
PubMed2001

MR urography in evaluation of acute flank pain: T2-weighted sequences and gadolinium-enhanced three-dimensional FLASH compared with urography. Fast low-angle shot.

OBJECTIVE: The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain. SUBJECTS AND METHODS: Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference. RESULTS: Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the detection of stones 3D FLASH was superior, with a sensitivity of 96.2% and 100% and specificity of 100% and 100% for observers A and B, respectively, compared with a sensitivity of 57.7% and 53.8% and a specificity of 100% and 100%, respectively, for T2-weighted sequences. The best degree of obstruction was seen with 3D FLASH, and the interobserver agreement was excellent for stone detection (kappa = 0.97). CONCLUSION: T2-weighted sequences alone are not sufficient for examining patients with acute flank pain. However, the combined use of both T2-weighted and 3D FLASH sequences will ensure better confidence in the evaluation of acute suspected renal colic. MR urography can replace conventional excretory urography when the latter is contraindicated or undesirable.

Acute Disease↗
PubMed2002

[Evaluation of the developing human visual system using flash-visual evoked potential].

Flash visual evoked potential (Flash-VEP) is easily recorded in preterm infants. However, its clinical application has not been established due to its great variability in response. Our longitudinal studies on the two components of the N1 wave facilitated peak definition and established normal ranges that are clinically valuable. The N1a (early component of the N1) peak latency decreases at about 4.6 msec/week between 30 and 40 weeks postmenstrual age. A flash-VEP study in the preterm period enables us to observe the neuronal development in the human visual system that normally proceeds in utero. Flash-VEP analyses on preterm infants demonstrated that the decrease in the N1a peak latency reflects the progress of myelination in the visual pathway according to the developmental program irrespective of preterm birth. The developmental changes of the N1 wave configuration reflect the maturation of the neuronal networks in the visual cortex, which is accelerated by extrauterine visual experience. Using improved methodology and peak denomination that we proposed, flash-VEP can be applied to preterm infants safely, and should provide us with neuro-developmental information of the human cerebrum.

Cerebral Hemorrhage↗
PubMedDate not supplied

Application of rapid, electrochemical Flash Titration to total acidity and alkalinity determinations in buffers, foods, and beverages.

A new technique (Flash Titration) for the determination of total acidity and total alkalinity was applied to food and beverage analysis. Requiring no liquid titrants, Flash Titration is a technique made possible through microfabrication of electrochemical components on a silicon chip. Acidic or basic titrant was generated electrochemically at a noble-metal electrode that intimately surrounded an ion-selective, field-effect transistor pH sensor. As acid or base was generated through electrolysis, sample alkalinity or acidity, respectively, was neutralized in the immediate vicinity of the electrode. Through diffusion, a zone comprising a gradient of partially to totally neutralized sample expanded from the generating electrode into the volume element sensed by the nearby pH sensor. An analysis of the pH signal versus time revealed an end point inflection at an elapsed time related to the total alkalinity or acidity of the sample. End point times were typically a few seconds. In this paper, Flash Titration was applied to the analysis of a variety of samples, including juices, soft drinks, wines, and food products. The differences between the results obtained by the Flash Titration method and a commonly used conventional volumetric method were less than 2% in most food products tested. Analysis costs were reduced both through time saving and reduction or elimination of hazardous liquid titrant disposal, by the use of the Flash Titration method.

Beverages↗
PubMedDate not supplied

[Electron paramagnetic resonance study of electron transport in photosynthetic systems. VIII. The interplay between two photosystems and kinetics of P700 redox transients under various conditions of flash excitation].

The kinetics P700 redox transients in bean chloroplasts induced by short (t 1/2 = 7 microsecond) flashes of white light has been studied. The flashes were fired in the dark or simultaneously with the continuous background far red light (707 nm). After oxidation of electron transport chain by 707 nm light only 50% of P700+ centres were reduced by photosystem 2 in response to the first flash of saturating intensity. The total reduction of P700+ centres was observed only after two or more saturating flashes. The similar data were obtained for various native photosynthetic systems (bean leaves and leaves of other higher plants). It has been shown that the quantitative difference in P700 behaviour after the first and following flashes may be interpreted in terms of a mechanism of the plastoquinol oxidation by photosystem 1. Twofold oxidation of one molecule of plastoquinol was assumed as its successive oxidation to plastosemiquinone and plastoquinone by different acceptors localized nea the same P700 centre (cytochrome f and plastocyanine). It has been shown that one molecule of plastoquinol was arised due to the interaction of two plastosemiquinones reduced by different P680 centre.

Chloroplasts↗
PubMed1985

Cytochrome c oxidase in plant mitochondria. Electron transfer after flash photolysis at low temperature of the CO-bound half-reduced complex.

Rebinding of CO after flash photolysis of the carboxy mixed-valence cytochrome c oxidase in plant mitochondria has been monitored in the visible range at low temperature (160-210K). At 586/630 nm, the photodissociation of the CO-saturated suspension was followed by a largely incomplete rebinding of CO to Fea3. After a series of three to four flashes, the unbound species accumulated up to 85% of the total enzyme, the remaining 15% CO-bound form undergoing recombination repetitively. In the Soret region, the absorbance level after the first flash came back to the initial one, as if all the CO-bound form were restored. However, the amount of complex which could be photodissociated by a second flash was only part of the starting material, in agreement with observations in the alpha range. The unbound species exhibited optical features very similar to the ones of compound C. The lack of CO rebinding is interpreted as due to an electron redistribution induced by the flash photolysis. This electron transfer has been tentatively assigned to a concomitant CuB oxidation and CuA reduction on the basis of the 655 nm band as a probe for a3+3 [Beinert et al. (1976) Biochim. Biophys. Acta 423, 339-355] and of the optical features in the visible range. Results are discussed with respect to analogous investigations with beef heart mitochondria and the studies by Boelens and Wever (1979-1982) of electron transfer after photolysis of the carboxy mixed-valence state when using the isolated mammalian enzyme at room temperature.

Animals↗
PubMed1983

[Effect of flash on optokinetic nystagmus and postoptokinetic reactions].

Chronic experiments in rabbits revealed disturbances of visual function and the rate of restoration of detecting sensitivity to perception of movements after flash,--by means of the duration of the optokinetic nystagmus (OKN) absence and the period of the optokinetic (OK) responses restoration after the action of flash on the retina. Besides, the duration od the reverse postoptokinetic nystagmus (RPN) after the flash was determined in presence of illuminated OK--cylinder and the stripes in visual field, the latters being an object of fixation under normal conditions leading to cessation of the RPN. The RPN under these conditions lasted for 64.1 +/- 4.3 sec after the flash, switching off the light leading to reappearance of the RPN. The OKN, in spite of the OK stimulation, is absent after the flash during 118.0 +/- 8.4 sec and reaches its initial level within 175.2 +/- 21.7 sec starting from the first stimulus.

Animals↗
PubMed1980

[Latency of visual evoked responses to diffuse and scanning flashes (author's transl)].

Visual evoked potentials (VEP) were produced in humans (normal and patients) by diffuse and scanning flashes. The responses to both stimulation techniques prove to be similar. Using the flash (or the start of the scanning flash) as trigger reference we find latency differences of the first positive major component P2 about 7 ms. Scanning flash stimulation seems to elicite retinal inhibitory and excitatory processes, comparable to the stimulation effects by diffuse flashes. Following these results the recorded potential is due to space-time-integrating systems related to the fovea and parafovea.

Cerebral Cortex↗
PubMed1981

Objective techniques for the assessment of postmenopausal hot flashes.

The present study was undertaken to evaluate objective methods of monitoring postmenopausal hot flashes. Continuous recordings of finger and core temperature and sternal skin conductance were carried out in 8 postmenopausal and 4 premenopausal women. Four postmenopausal patients were studied a second time following 30 days of daily oral administration of ethinyl estradiol 0.05 mg. One hundred twenty flashes were subjectively noted and recorded during 104 hours of study in the postmenopausal women. Eighty-two, 98, and 81% of subjective flashes were associated with changes in finger temperature, skin conductance, and core temperature, respectively. The rate of occurrence and magnitude of changes of physiologic markers were significantly greater (P less than .01) in postmenopausal than premenopausal women. Estrogen replacement therapy not only eliminated the subjective sensations but also significantly reduced (P less than .02) the frequency and magnitude of the changes in physiologic function measured by finger temperature. Measurement of skin conductance changes was the single most sensitive and specific indicator of hot flashes. The simultaneous change of both skin conductance and finger temperature, although less sensitive, was a very specific indicator of a hot flash. These results support the concept that the measurement of physiologic changes can be used to assess objectively the occurrence of this symptom complex.

Adult↗
PubMed1994

Flash-induced absorption spectroscopy studies of copper interaction with photosystem II in higher plants.

Measurements of flash-induced absorption changes at 325, 436, and 830 nm and of oxygen evolution were performed in order to analyze in detail the inhibition of photosystem II (PS II) by Cu(II) in PS II membrane fragments from spinach. (a) The kinetics of P680+ reduction become markedly slower in the presence of 100 microM CuSO4. (b) The CuSO4-induced kinetics of P680+ reduction are dominated by a 140-160-microsecond decay. (c) The extent of these 140-160-microsecond kinetics, normalized to the overall decay, remains virtually unaffected by addition of the exogenous PS II donor, NH2OH. (d) In thoroughly dark-adapted samples the CuSO4-induced 140-160-microsecond kinetics are already observed after the first flash and remain unchanged by a train of excitation flashes. (e) The extent of P680+ and QA- formation under repetitive flash excitation is not diminished by addition of 100 microM CuSO4. (f) The induction of microsecond kinetics of P680+ reduction at the expense of ns kinetics and the inhibition of the saturation rate of oxygen evolution exhibit the same dependence on CuSO4 concentration. (g) CuSO4 also transforms the 10-20-microsecond reduction of P680+ by TyrZ in Tris-washed PS II membrane fragments into 140-160-microsecond kinetics without any effect on the extent of flash-induced P680+ formation. These results unambiguously show that Cu(II) does not affect the charge separation (P680+QA-), but instead specifically modifies TyrZ and/or its micro environment so that the electron transfer to P680+ becomes blocked.

Copper↗
PubMed1994

Antibiotic prophylaxis in pulmonary surgery. A prospective randomized double-blind trial of flash cefuroxime versus forty-eight-hour cefuroxime.

The aim of this study was to determine whether a 48-hour antibiotic prophylaxis regimen with a second-generation cephalosporin was more efficient than a flash antibiotic prophylaxis regimen in pulmonary operations. All the included patients underwent lung resection. Patients with preoperative infection were excluded. All the patients were given cefuroxime (1.5 gm intravenously) at the time of the anesthetic induction and again 2 hours later. The randomization was done postoperatively: group 1 was given placebo intravenously (n = 102) and group 2 was given cefuroxime intravenously (n = 101), each every 6 hours for 48 hours. The overall rate of infections was 46% in the 48-hour cefuroxime group versus 65% in the flash group (p = 0.005). The difference remained significant even after an adjustment with prognosis variables (p = 0.01). Six empyemas (6%) in the flash group were noted versus one (1%) in the 48-hour group (p = 0.03). From day 3 to day 8 after the operation, chest x-rays films were more often assessed as being normal in the flash group than in the 48-hour group (p = 0.005). On day 3 after operation, white blood cell counts were 13,020 +/- 1,220 elements/mm3 in the flash group versus 11,620 +/- 1,220 elements/mm3 in the 48-hour group (p = 0.03). A 48-hour antibiotic prophylaxis regimen decreases the rate of deep infections and particularly the rate of empyemas.

Bronchopneumonia↗