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Biomedical subjects

M Fu

Publications and source records attributed to M Fu.

At least 217 records · Page 12Linked to original sources
PubMed1986

Importance of adequate gas-mixing in contrast echocardiography.

Microbubble formation has been accepted as the mechanism producing contrast echoes. Comparisons of the contrast effects of various agents have been studied extensively, but the importance of gas-mixing has been less appreciated. To test the hypothesis that good gas-mixing, by facilitating microbubble formation, would enhance contrast effect, this study compared the contrast echocardiograms of ten adult patients before and after mixing carbon dioxide with various contrast agents. Contrast agents tested included a 5 percent glucose in water, vitamin B complex, vitamin C, and Cardiogreen solutions. First, we recorded echocardiograms by injecting each diluted contrast solution alone, then repeated the examinations using 10 ml of each diluted solution with 1 ml of carbon dioxide (CO2), mixed by means of a four-way stopcock. Satisfactory or excellent results were obtained in seven of ten, ten of ten, ten of ten, and ten of ten tests, respectively, after thorough gas-mixing, vs one of ten, seven of ten, eight of ten, and six of ten, respectively, before gas-mixing. We conclude that the addition of sufficient amounts of gas, followed by thorough mixing, is of great importance in contrast echocardiography. Consistently good results can be achieved with vitamin C, vitamin B or Cardiogreen solutions by this simple and safe method.

Adolescent↗
PubMed1985

Serial electrophysiologic studies of the effects of oral diltiazem on paroxysmal supraventricular tachycardia.

In 16 patients with paroxysmal supraventricular tachycardia, electrophysiologic studies were done before and serially at hourly intervals for eight hours after the third oral dose of 90 mg diltiazem given every eight hours. Diltiazem increased both the longest atrial paced cycle length producing type 1 atrioventricular block and the effective refractory period of the atrioventricular conducting system at all measurements. Before diltiazem, all 16 patients had induction of sustained tachycardia. After diltiazem, sustained tachycardia could not be induced in ten patients at any measurements; in these patients, either echo or nonsustained tachycardia was induced. In the remaining six patients, sustained tachycardia was induced, particularly after six hours. Follow-up observations in 12 patients receiving the same dosage of oral diltiazem for 6 +/- 2 months (mean +/- SD), showed that of the eight patients in whom electrophysiologic testing induced either echo or nonsustained tachycardia, six were asymptomatic and two experienced transient palpitation. Of the other four patients with induction of sustained tachycardia, three had transient palpitation and one had occasional attacks of sustained tachycardia requiring modification of therapy. Thus, oral diltiazem increases atrioventricular nodal refractoriness, with an effect lasting up to eight hours. It is an effective agent for the prophylaxis of paroxysmal supraventricular tachycardia.

Administration, Oral↗
PubMed1984

Usefulness of intravenous diltiazem in predicting subsequent electrophysiologic and clinical responses to oral diltiazem.

Diltiazem, 0.25 mg/kg, was given intravenously during induced tachycardias in 6 patients with atrioventricular (AV) nodal reentrant tachycardia (group I) and in 24 patients with AV reentrant tachycardia incorporating a retrogradely conducting accessory pathway (group II). In all 6 group I and in 15 of 24 group II patients, tachycardias terminated within 1 minute after diltiazem administration, with a weak link in the anterograde direction. In 3 other patients in group II, tachycardias were terminated by a premature ventricular complex within 1 minute. In the remaining 6 patients in group II, in whom tachycardias failed to terminate, rates of tachycardias decreased as a result of suppression of anterograde AV nodal conduction by diltiazem. Electrophysiologic studies were performed subsequently 2 hours after the third dose of 90 mg of diltiazem, which was given orally at 8-hour intervals. In 18 responders to intravenous diltiazem who were subjected to oral diltiazem testing, sustained supraventricular tachycardia (SVT) could be induced in only 2. Of the 6 nonresponders, sustained tachycardias could not be induced in 3. Twelve patients, including 11 responders and 1 nonresponder to intravenous diltiazem who responded to oral diltiazem testing, were discharged with oral diltiazem therapy, 90 mg every 8 hours, with follow-up periods of 2 to 13 months (mean 7 +/- 4 [+/- standard deviation]). The frequency of recurrent SVT decreased significantly; 8 patients were free of tachycardias and 4 had occasional recurrences of SVT that required no hospital visit. In conclusion, intravenous diltiazem is effective in terminating SVT. Termination of SVT by intravenous diltiazem predicts subsequent electrophysiologic and clinical responses to oral diltiazem.

Administration, Oral↗
PubMedDate not supplied

Efficacy and safety of acetaminophen in the treatment of migraine: results of a randomized, double-blind, placebo-controlled, population-based study.

BACKGROUND: Although most persons with migraine treat their headaches with over-the-counter medication, systematic data on the safety and efficacy of widely used treatment, including acetaminophen, are sparse. METHODS: This is a randomized, double-blind, placebo-controlled study comparing oral acetaminophen, 1000 mg (two 500-mg Extra Strength Tylenol tablets), with identical placebo in the treatment of a single acute migraine attack. Eligible subjects met International Headache Society diagnostic criteria for migraine with or without aura. Patients who usually required bed rest with their headaches or who vomited more than 20% of the time were excluded. MAIN OUTCOME MEASURES: The percentage of subjects who, at 2 hours after dosing, experienced a change in baseline pain intensity from severe or moderate pain to mild or no pain (headache response); and pain intensity difference from baseline at the 2-hour postmedication assessment. RESULTS: The headache response rate 2 hours after dosing was 57.8% in the acetaminophen group and 38.7% in the placebo group (P =.002). Pain-free rates at 2 hours were 22.4% in the acetaminophen group and 11.3% in the placebo group (P =.01). The mean pain intensity difference from baseline 2 hours after dosing was 1.08 in the acetaminophen group and 0.73 in the placebo group (P<.001). At 2 hours, other migraine headache characteristics, such as functional disability (P =.002), photophobia (P =.02), and phonophobia (P =.08), were significantly improved after treatment with acetaminophen vs placebo. CONCLUSIONS: Acetaminophen was highly effective for treating pain, functional disability, photophobia, and phonophobia in a population-based sample of persons with migraine, excluding the most disabled persons with migraine. The drug also had an excellent safety profile and was well tolerated. Arch Intern Med. 2000;160:3486-3492.

Acetaminophen↗
PubMedDate not supplied

Dissection of retroesophageal aortic diverticulum and descending aorta in a patient with right aortic arch: magnetic resonance demonstration.

An acute aortic dissection involved the retroesophageal aortic diverticulum (RAD) and descending thoracic aorta in a patient with right aortic arch. The RAD, which was separated into false and true lumens by an intimal flap-the classic diagnostic sign of aortic dissection-was overlooked on transesophageal echocardiography and computed tomography but was clearly depicted on magnetic resonance imaging (MRI). It was found that MRI can delineate the anatomy of a congenital arch anomaly complicated by great vessels disease.

Aortic Dissection↗
PubMedDate not supplied

Contrast transesophageal echocardiographic demonstration of coronary artery fistula within left atrial appendage thrombus in mitral stenosis.

Coronary neovascularization and fistula formation arising from the left circumflex artery demonstrated by coronary angiography is a specific sign for the presence of left atrial appendage thrombus in patients with mitral stenosis. However, the fistula drainage site in the left atrium in relation to the thrombus cannot be ascertained by the angiographic method. We performed transesophageal echocardiography simultaneously with coronary angiography in five patients with severe mitral stenosis and left atrial appendage thrombus. The angiography showed coronary neovascularization and fistula arising from the left circumflex artery in three patients. In these three patients, the transesophageal echocardiography confirmed the presence of a coronary fistula by identifying contrast exuding from the surface of the thrombus. Thus we have shown for the first time the usefulness of contrast transesophageal echocardiography in imaging the exact drainage site of coronary artery fistula from left atrial appendage thrombus.

Aged↗
PubMedDate not supplied

Doppler atrial shunt flow patterns in patients with secundum atrial septal defect: determinants, limitations, and pitfalls.

Fifteen patients with uncomplicated secundum atrial septal defect underwent studies with real-time color-coded two dimensional flow imaging, pulsed Doppler echocardiographic examination, and simultaneous pressure recordings from the left and right atrium to determine the flow-pressure dynamics of the atrial shunt flow. In all 15 patients both the color flow mapping and pulsed Doppler studies revealed that the shunt flow was mainly from left to right, occurring both during ventricular systole and diastole. It started in early systole, reached a peak in late systole to early diastole, and lasted throughout diastole with an accentuation in late diastole during atrial contraction. The amplitude of the flow velocity, the direction, and the magnitude of the shunt flow, however, changed from phase to phase during the cardiac cycle. It correlated well with the phasic variation of the interatrial pressure difference, which usually revealed a peak pressure gradient that occurred in early systole between the x descent and v wave and during the period of v wave and a wave of the left atrial pressure tracing. Right to left shunt was not detected in any of the 15 patients by color flow mapping studies. A minor reversal of the shunt flow, however, was frequently detected at the beginning of ventricular systole and sometimes also in the middle of diastole by pulsed Doppler echocardiography. The reversal of shunt flow correlated with the minor reversal of pressure gradient that occurred during the z point, x descent, and y descent of the left atrial pressure tracing. In conclusion, left to right shunt flow occurs both during ventricular systole and diastole in uncomplicated secundum atrial septal defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Efficacy of nonprescription doses of ibuprofen for treating migraine headache. a randomized controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of ibuprofen, 200 mg and 400 mg, compared with placebo and each other for the treatment of pain of migraine headache. BACKGROUND: Migraine headache is a common illness with significant social and economic impact. DESIGN: Randomized, placebo-controlled, double-blind trial of 6 hours' treatment duration. METHODS: Fifteen investigators at 17 private practice and referral centers in the United States participated in this study of 660 outpatient adults aged 18 to 84 years with migraine headache of moderate to severe intensity. Each patient was randomly assigned to a single dose of study medication: ibuprofen 200 mg (n = 216) or 400 mg (n = 223), or placebo (n = 221). The percentage of patients with a reduction in baseline headache intensity from severe or moderate to mild or none 2 hours after treatment and the headache pain intensity difference from baseline at 2 hours were the primary efficacy measures. Secondary outcomes included other measures of pain relief, severity differences from baseline for migraine-associated symptoms of nausea, photophobia, phonophobia, and functional disability, and percentage of patients with migraine-associated symptoms reduced to none. RESULTS: Significantly (P < or = .006) more patients treated with ibuprofen, 200 mg or 400 mg, reported mild to no pain after 2 hours (41.7% and 40.8%, respectively), compared with those treated with placebo (28.1%). The mean pain intensity difference from baseline measured at 2 hours was significantly (P < or = .001) greater for patients treated with ibuprofen 200 mg or 400 mg (0.68 and 0.65, respectively), compared with those treated with placebo (0.39). Statistically significant differences in favor of both doses of ibuprofen over placebo were observed for mean pain intensity difference at 1 hour after treatment. In patients with severe baseline pain intensity, ibuprofen, 400 mg, was significantly (P < or = .048) superior to placebo for the primary efficacy end points, while ibuprofen, 200 mg, was not. Ibuprofen, 200 mg and 400 mg, were statistically significantly more effective than placebo for all clinically important secondary pain relief outcomes. Mean severity changes of migraine-associated symptoms of nausea, photophobia, phonophobia, and functional disability at 2 and 6 hours were significantly (P < or = .03) in favor of both doses of ibuprofen over placebo, and results for the percentage of patients with symptoms reduced to none consistently, although less often statistically significant, favored ibuprofen. No statistically significant differences in adverse events were found among treatment groups. CONCLUSIONS: Ibuprofen at doses of 200 mg and 400 mg is an efficacious, cost-effective, well-tolerated, single-ingredient nonprescription treatment for pain of migraine headache. In addition, while not always statistically significant, ibuprofen provided a beneficial effect on associated symptoms of migraine including nausea, photophobia, phonophobia, and functional disability.

Adult↗
PubMedDate not supplied

Transcriptional activation of an intermediate filament protein gene in mice with retinal dystrophy.

We are interested in understanding neuronal interactions that regulate expression of specific genes in glial cells in the nervous system. In the normal mouse retina, the glial intermediate filament protein (GFAP) is not detectable in Müller cells, the predominant glial cells in the retina. Photoreceptor degeneration resulting from retinal degeneration (rd) mutation or environmental light damage, however, leads to the appearance of GFAP in Müller cells. We have investigated the mechanism underlying GFAP accumulation in these retinas. Western blotting analysis, steady-state mRNA level comparisons, and nuclear run-on assays show that transcription of the GFAP gene is activated in these retinas. In situ hybridizations with retinal sections and solitary Müller cells establish that GFAP mRNA levels are elevated in Müller cells. These results show that disruption of neuron-glia interactions resulting from photoreceptor degeneration leads to activation of the GFAP gene in glial cells of mice with retinal dystrophy. The functional significance of this glial response and the need for GFAP expression remain to be understood.

Animals↗
PubMedDate not supplied

Computer simulation of sensorless fuzzy control of a rotary blood pump to assure normal physiology.

Rotary blood pumps have been considered effective permanently implantable devices. However, control of such pumps is quite complicated. Sensorless control of pump flow is required because no invasive flow or pressure sensors are wanted. Whereas insufficient pump output can cause underperfusion and should be avoided, overpumping may cause ventricular collapse and must be prevented. An intelligent physiologic control algorithm is highly desirable to reach optimal pump output based on physiologic requirements. We present an intelligent physiologic control mechanism for the blood pump allowing it to achieve normal physiology. Sensorless control of pump flow is gained by analysis of the electric motor current and speed. The required pump output flow is chosen based on heart rate, and an intelligent fuzzy logic based control mechanism is developed to adjust the motor input so that the pump output can reach required flow while also preventing the occurrence of ventricular suction or cannular collapse. Computer simulation was carried out, and the results indicate that the proposed algorithms can achieve required pump flow to obtain normal physiology, whereas overpumping can be prevented to provide safe operation.

Algorithms↗