Coherent-ordered transition in chaotic globally coupled maps.
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Journal Article↗
Biomedical subjects
F Xie
Publications and source records attributed to F Xie.
Interaction of diagnostic ultrasound with synthetic oligonucleotide-labeled perfluorocarbon-exposed sonicated dextrose albumin microbubbles.
The purpose of this study was to determine, first, whether the albumin on perfluorocarbon-exposed sonicated dextrose albumin microbubbles has retained its known ability to bind antisense oligonucleotides (DNA utilized to inhibit viral replication and intimal hyperplasia). The binding kinetics of synthetic antisense oligonucleotides to perfluorocarbon-exposed sonicated dextrose albumin microbubbles as well as to room air-containing sonicated dextrose albumin microbubbles were compared. Second, the effect of diagnostic ultrasound on this binding is unknown. The ability of diagnostic ultrasound to release synthetic antisense oligonucleotides from perfluorocarbon-exposed sonicated dextrose albumin microbubbles also was tested in vitro and in vivo in three dogs. Synthetic antisense oligonucleotides exhibited binding to perfluorocarbon-exposed sonicated dextrose albumin microbubbles much like that of native albumin but did not bind uniformly with room air-containing sonicated dextrose albumin microbubbles. Diagnostic ultrasound resulted in significant partitioning of synthetic antisense oligonucleotides into non-bubble containing regions after insonation in vitro as well as deposition of greater amounts of synthetic antisense oligonucleotides in the insonated kidney after intravenous injections of synthetic anti-sense oligonucleotide-labeled perfluorocarbon-exposed sonicated dextrose albumin microbubbles. We conclude that perfluorocarbon-exposed sonicated dextrose albumin microbubbles, unlike room air-containing sonicated dextrose albumin microbubbles, have bioactive albumin on their surface that can bind synthetic antisense oligonucleotides and then release them in the presence of diagnostic ultrasound.
Animals↗
Transient myocardial contrast after initial exposure to diagnostic ultrasound pressures with minute doses of intravenously injected microbubbles. Demonstration and potential mechanisms.
BACKGROUND: We have observed a transient but significant increase in myocardial contrast intensity with intravenously injected perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles that occurs on initial exposure to pulsed ultrasound (transient-response imaging). The characteristics and magnitude of this response were examined in the present study. METHODS AND RESULTS: In 14 dogs, the myocardial contrast intensity produced by transient-response imaging (TRI) was compared with conventional 30-Hz imaging (CI) after a 0.005 to 0.030 mL/kg intravenous injection of PESDA. TRI was produced either by measuring myocardial contrast during triggered (1 pulse per cardiac cycle) ultrasound or by withholding real time ultrasound transmission until after microbubbles had entered the myocardium after intravenous injection. Both first-harmonic imaging (2.0 to 3.5 MHz) and second-harmonic imaging (2.0 to 2.5 MHz fundamental, 4.0 to 5.0 MHz received) were used. TRI produced over three times the anterior myocardial contrast intensity of CI (36 +/- 12 U TRI versus 11 +/- 11 U CI; P < .01), with visually better anterior and posterior myocardial contrast. The spatial extent of myocardial ischemia was easily visualized after intravenous PESDA by use of TRI and correlated closely with risk area as measured with Monastral blue (r = .99, P = .002). CONCLUSIONS: TRI produces significantly greater myocardial contrast than CI and may dramatically enhance the ability of intravenous ultrasound contrast agents to identify myocardial perfusion abnormalities.
Animals↗
Segmental analysis of coronary arteries with equivalent plaque burden by intravascular ultrasound in patients with and without angiographically significant coronary artery disease.
These IVUS-derived data indicate that failure of compensatory dilation is an important factor in the development of clinically and angiographically significant coronary artery disease independent of plaque burden. We observed an actual reduction in total vessel area at the most stenotic site in coronary arteries that had a quantitatively significant angiographic lesion.
Aged↗
Improved detection limit for catecholamines using liquid chromatography-electrochemistry with a carbon interdigitated array microelectrode.
The detection limit of catecholamines can be lowered by using a carbon-based interdigitated array (IDA) microelectrode as a detector for liquid chromatography (LC). The IDA electrode is more sensitive than conventional glassy carbon electrodes due to the high current density caused by radial diffusion at each microband, and redox cycling between two microband arrays. Since the number of redox cycles increases at lower flow-rates, the carbon IDA is particularly useful for microbore LC. In an LC system with a 1-mm microbore column and a carbon IDA electrode, the peak height of dopamine (DA) and DOPAC did not decrease with decreasing flow-rate because of this redox cycling. A low detection limit of 5 fg (32 amol) and 9.6 fg (57 amol) was obtained for DA and DOPAC due to the high current density and low background noise level (0.1 pA) at the carbon IDA electrode. The total charge generated by oxidizing DA at the anodic array was more than the value calculated by assuming that all the DA molecules were oxidized.
3,4-Dihydroxyphenylacetic Acid↗
Induction of c-fos in mouse bone marrow macrophages: a direct method for assessing bone marrow cell activation.
Intravenous LPS was used to induce bone marrow cell activation in c-fos/lacZ transgenic mice. Activated bone marrow cells were identified by staining with X-gal and cell lineage was determined using specific monoclonal antibodies. Four hours after intravenous injection of 100 micrograms LPS, 2.8 +/- 0.2% (28/1000) of total bone marrow cells was X-gal positive as compared to 0 +/- 0% (0/1000) of cells from untreated animals. CD8a, CD4 and CD45R antigens were not expressed on X-gal positive cells suggesting they were not from the T or B lymphocyte lineage. In contrast, Ly-6c, CD44 and Gr-1 antigens were expressed on 51 +/- 6%, 85 +/- 9% and 37 +/- 5% of X-gal positive cells, indicating that X-gal positive cells were from macrophage or granulocyte lineages. The presence of non-specific esterase and the lack of peroxidase activity in X-gal positive cells was used to conclude that X-gal positive cells were of macrophage lineage.
Animals↗
Phase I clinical trial of continuous infusion cyclopentenyl cytosine.
Cyclopentenyl cytosine (CPE-C) is an investigational drug that is active against human solid tumor xenografts. The 5'-triphosphate of CPE-C inhibits CTP synthase, and depletes CTP and dCTP pools. We conducted a phase I clinical trial of CPE-C given as a 24-h continuous i.v. infusion every 3 weeks in 26 adults with solid tumors. The starting dose rate, 1 mg/m2 per h, was selected on the basis of both preclinical studies and pharmacokinetic data from two patients obtained after a test dose of 24 mg/m2 CPE-C as an i.v. bolus. Dose escalation was guided by clinical toxicity. A total of 87 cycles were given, and ten patients received four or more cycles. The mean CPE-C steady-state plasma levels (Cpss) increased linearly from 0.4 microM to 3.1 microM at dose levels ranging from 1 to 5.9 mg/m2 per h (actual body weight); the mean total body clearance was 146 +/- 38 ml/min per m2. CPE-C was eliminated by both renal excretion of intact drug and deamination to cyclopentenyl uracil in an apparent 2:1 ratio. CTP synthase activity in intact bone marrow mononuclear cells was inhibited by 58% to 100% at 22 h compared to matched pretreatment samples at all CPE-C dose levels. When all data were combined, flux through CTP synthase was decreased by 89.6% +/- 3.1% at 22 h (mean +/- SE, n = 16), and remained inhibited by 67.6% +/- 7.7% (n = 10) for at least 24 h post-CPE-C infusion. Granulocyte and platelet toxicities were dose-dependent, and dose-limiting myelosuppression occurred during the initial cycle in two of three patients treated with 5.9 mg/m2 per h. Four of 11 patients (4 of 20 cycles) who received 4.7 mg/m2 per h CPE-C experienced hypotension 24-48 h after completion of the CPE-C infusion during their first (n = 2), third (n = 1) and sixth cycles (n = 1), respectively. Two of these patients died with refractory hypotension despite aggressive hydration and cardiopulmonary resuscitation. One of 12 patients (28 total cycles) treated with 3.5 mg/m2 per h CPE-C experienced orthostatic hypotension during cycle 1, and this patient had a second episode of orthostatic hypotension at a lower dose (3.0 mg/m2 per h). Hypotension was not seen in patients receiving < or = 2.5 mg/m2 per h CPE-C.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
The mechanism and clinical implication of improved left ventricular videointensity following intravenous injection of multi-fold dilutions of albumin with dextrose.
The left ventricular ultrasound videointensity of an intravenous injection of sonicated albumin is improved if the agent is diluted with dextrose prior to sonication. The objective of this study was to determine the mechanism for improved left ventricular ultrasound contrast with intravenous sonicated multi-fold dilutions of albumin with dextrose compared to sonicated albumin alone. Epicardial short axis images of the left ventricle were obtained in 11 mongrel dogs and incremental one part sonicated dilutions (up to 10-fold) of albumin with 5 or 50% dextrose were given intravenously to determine which dilution and dextrose concentration produced optimal left ventricular videointensity. Microbubble size and concentration of these dilutions were measured. The one to seven-fold sonicated dilutions resulted in a slight, but significantly larger microbubble size when compared to sonicated albumin alone (SA), but no difference in concentration. All dilutions produced significantly higher end-diastolic peak videointensity (PVI) in the left ventricle than SA (range 160-569% of SA PVI; p < 0.001) with the three to five-fold dilution producing maximal PVI. Five percent dextrose dilutions produced the same videointensity as 50% dilutions. End-systolic videointensity of both 5 and 50% dextrose dilutions were also over 250% higher than SA (p < 0.001). This resulted in good or excellent end-systolic endocardial border definition in the majority of injections. Therefore, the mechanism for improved left ventricular chamber opacification with multifold sonicated dilutions of albumin with dextrose appears to be due to a small increase in microbubble size and not increased viscosity or microbubble concentration.
Albumins↗
Visually discernible myocardial echocardiographic contrast after intravenous injection of sonicated dextrose albumin microbubbles containing high molecular weight, less soluble gases.
OBJECTIVES: The central hypothesis of this study was that microbubble survival, and subsequent left ventricular and myocardial ultrasound contrast, could be improved by altering microbubble gas to consist of a higher molecular weight (less diffusible) and less soluble gas. BACKGROUND: Microbubble survival after intravenous injection is shortened because of rapid diffusion of blood-soluble room air gases (nitrogen and oxygen) across the permeable bubble membrane into blood. METHODS: Thirteen open chest dogs received intravenous injections of a constant dose of sonicated dextrose albumin that was incubated with either room air or 100% nitrogen, 100% helium or 100% sulfur hexafluoride. Nitrogen (100%) is less blood soluble than room air, whereas helium and sulfur hexafluoride are the least soluble. Sulfur hexafluoride has the slowest diffusion rate. To further decrease the diffusion rate, each sample was administered during inhalation of room air and again during brief inhalation of the same gas with which it had been incubated. RESULTS: The highest peak videointensity in the left ventricular cavity was produced by the sonicated dextrose albumin incubated with sulfur hexafluoride, the gas having lowest blood solubility and diffusion rate, while sulfur hexafluoride was briefly inhaled during the period of intravenous injection (peak videointensity 139 +/- 10 vs. 54 +/- 11 for room air-exposed sonicated dextrose albumin, p < 0.001). Myocardial contrast was visually evident in > 80% of the intravenous injections of sulfur hexafluoride-exposed sonicated dextrose albumin when the agent was given as an 8-fold concentrated sample during brief inhalation of sulfur hexafluoride. CONCLUSIONS: Visual myocardial echocardiographic contrast is possible after intravenous injection of sonicated dextrose albumin if the microbubbles contain a gas with low blood solubility and diffusivity.
Albumins↗
Noninvasive identification of acute myocardial ischemia and reperfusion with contrast ultrasound using intravenous perfluoropropane-exposed sonicated dextrose albumin.
OBJECTIVES: The purpose of this study was to determine whether intravenous dextrose albumin sonicated with a commonly used gas of low blood solubility and diffusivity (perfluoropropane) could identify acute myocardial ischemia and reperfusion. BACKGROUND: Recently, it has been demonstrated that dextrose albumin sonicated with gases that have low blood solubility and diffusivity results in microbubbles capable of consistently producing myocardial ultrasound contrast after intravenous injection. It remains to be determined, however, whether this contrast agent can visually detect the myocardial blood flow abnormalities seen with acute ischemia or stunned myocardium after reperfusion. METHODS: We gave intravenous injections (0.06 ml/kg body weight) of perfluoropropane-exposed sonicated dextrose albumin to 10 open chest dogs. The measured degree of myocardial contrast (0+ to 2+) and background-subtracted peak anterior myocardial videointensity produced from each injection were measured at three stages: 1) under baseline conditions, 2) during acute ischemia produced by a proximal left anterior descending coronary artery ligation lasting 10 to 120 min, and 3) after reflow was established. Coronary blood flow was monitored during all injections by using an ultrasound flow probe placed around the left anterior descending artery. RESULTS: Coronary blood flow ranged from 0 to 137 ml/min, and peak myocardial videointensity after intravenous administration of perfluoropropane-exposed sonicated dextrose albumin ranged from 0 to 70 gray scale U. There was consistent visual myocardial opacification in all dogs during baseline conditions and a visually evident decrease in myocardial contrast in the left anterior descending artery distribution after ligation. A relative increase in contrast in this same distribution after intravenous contrast agent administration occurred in 7 of the 10 dogs during reflow. Quantitatively, there was an excellent correlation in individual dogs between peak myocardial videointensity and coronary flow at all stages (mean correlation coefficient 0.95 +/- 0.04, range 0.87 to 0.99). CONCLUSIONS: Perfluoropropane-exposed sonicated dextrose albumin is an ultrasound contrast agent that can visually identify myocardial perfusion abnormalities from a peripheral venous injection.
Acute Disease↗
Periodic solutions and bifurcation behavior in the parametrically damped two-well Duffing equation.
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Journal Article↗
On-off intermittency in a coupled-map lattice system.
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Journal Article↗
Synthesis and spontaneous dimerization of the tri-O-benzyl derivative of "2-keto-1-C-methylene-D-glucopyranose" (2,6-anhydro-4,5,7-tri-O-benzyl-1-deoxy-D-arabino-hept-1-en-3-ulose+ ++).
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Arabinose↗
Left ventricular volume changes during dobutamine stress echocardiography identify patients with more extensive coronary artery disease.
OBJECTIVES: We hypothesized that patients with more extensive coronary artery disease could be identified by abnormal left ventricular volume changes during dobutamine stress echocardiography. BACKGROUND: In patients with more than one significant coronary artery stenosis, the typical hypercontractile function during dobutamine infusion may not occur. This may result in a smaller decrease or even an increase in left ventricular volumes at peak dobutamine infusion. METHODS: We measured end-diastolic and end-systolic volumes in 61 patients undergoing dobutamine stress echocardiography and quantitative coronary analysis. Stress echocardiographic findings were positive in 39 patients (Group I) and negative in 22 (Group II). The percent change in these volume measurements from baseline to peak infusion were compared with quantitative coronary analysis jeopardy scores and incidence of two- or three-vessel coronary artery disease. An abnormal response was defined as < 15% decrease in end-diastolic or end-systolic volume. RESULTS: Among the 39 patients with positive findings on dobutamine stress echocardiography (Group I), 11 had an abnormal end-diastolic volume response (< 15% decrease). Nine of these patients had two- or three-vessel coronary artery disease compared with 11 of 28 patients with a normal volume response (p < 0.05). In the 22 patients with negative findings on dobutamine stress echocardiography (Group II), an abnormal end-diastolic volume response was seen in 12 patients, 8 of whom had two- or three-vessel coronary artery disease, whereas none of the 10 patients with a normal volume response had two- or three-vessel coronary disease (p < 0.005; sensitivity 100%, specificity 68%). In the 12 patients with no significant coronary artery disease, end-diastolic and end-systolic volumes decreased by > 15% in all but 1. CONCLUSIONS: Failure of end-diastolic volume to significantly decrease during dobutamine stress echocardiography identifies a group of patients with more extensive significant coronary artery disease.
Aged↗
Improved endocardial border resolution during dobutamine stress echocardiography with intravenous sonicated dextrose albumin.
OBJECTIVES: The purpose of this study was to determine whether intravenous sonicated dextrose albumin could improve endocardial border resolution during dobutamine stress echocardiography. BACKGROUND: Sonicated albumin improves endocardial border resolution in patients undergoing exercise stress echocardiography. Because a sonicated mixture of albumin with dextrose results in better transpulmonary passage than sonicated albumin alone, this agent could be utilized to further improve endocardial border resolution during dobutamine stress echocardiography. METHODS: We gave intravenous injections of sonicated dextrose and albumin to 50 patients undergoing dobutamine stress echocardiography. Left ventricular video intensity, contrast agent persistence (in seconds), number of contrast agent-enhanced cardiac cycles and improvement in endocardial border resolution were assessed from the apical four-chamber view at baseline, low dose (10 micrograms/kg body weight per min) and peak dobutamine infusion. RESULTS: There was significantly better left ventricular peak video intensity at peak dobutamine infusion than after the same injection at baseline (p < 0.005, analysis of variance). The number of contrast agent-enhanced cardiac cycles in the left ventricular cavity was also significantly longer at peak infusion. Endocardial border resolution was improved (mainly in lateral segments) in 93% of patients at low dose and 95% of patients at peak infusion. CONCLUSIONS: Intravenous sonicated dextrose albumin improves endocardial border resolution during dobutamine stress echocardiography.
Aged↗
Composition of coronary atherosclerotic plaque in the intima and media affects intravascular ultrasound measurements of intimal thickness.
OBJECTIVES: The purpose of this study was to evaluate how intravascular ultrasound-determined thickness and reflectivity of the inner echogenic layer of coronary artery plaque is affected by changes in collagen, elastin, proteoglycan, calcium and lipid content in the intima and media. BACKGROUND: Coronary artery plaque often results in disruption of the internal elastic lamina and in increased collagen in the media as well as increased intimal lipid, calcium and proteoglycan content. How these factors affect intravascular ultrasound-derived measurements of intimal thickness are unknown. METHODS: Twenty-one coronary artery segments from 10 patients with varying degrees of coronary artery disease were obtained fresh and unfixed at autopsy. Intravascular ultrasound (30-MHz, 3.5F catheter) was performed at regions in the vessel where a three-layered region was evident. Quantitative measurements of inner echogenic and deeper echolucent layer thickness were determined as well as estimates of ultrasound reflectivity and compared with histologic measurements of intimal and medial thickness and collagen, proteoglycan, lipid and calcium content. RESULTS: In plaque > 300 microns thick and equivalent histologic levels of collagen, inner echogenic layer reflectivity was greater in regions with a greater amount of calcium and proteoglycan and lesser amounts of lipid. Inner echogenic layer thickness correlated well with intimal thickness but had the best correlation with intimal and medial thickness when medial collagen content was increased (r = 0.89). The median observed difference between intimal and inner echogenic thickness was 160 (p < 0.05 compared with zero), whereas the median observed difference between inner echogenic thickness and intimal plus medial thickness when medial collagen content was increased was 60 (not significantly different from zero). CONCLUSIONS: The inner echogenic layer of human coronary artery plaque may represent both intima and media. The echolucent layer by ultrasound may represent only the basal section of the media that does not contain high collagen content.
Adult↗
[Study on influence degree of probability of endemic factors for schistosomiasis transmission in Yunnan mountainous regions].
In Zhonghe Village of Weishan County, Yunnan Province, a schistosomiasis endemic area of mountainous valley subtype, an epidemiological investigation was conducted on its natural, biological and social factors influencing schistosomiasis transmission in 1987-1990. The results were analyzed by stratified sampling analysis and probability accumulation method. It was demonstrated that 12 of 29 factors were the most important factors influencing schistosomiasis transmission including annual average air-temperature, number of infection sources, number of spots with infected snails, water temperature and annual average rainfall, etc. The values of influence degree before and after intervention measures were 3.513 and 2.066, respectively, the decrease being 41%.
Animals↗
Measurement of cyclopentenyl cytosine 5'-triphosphate in vitro and in vivo by multidimensional high-performance liquid chromatography.
Cyclopentenyl cytosine 5'-triphosphate (CPEC-TP) is the active metabolite of the investigational drug cyclopentenyl cytosine (CPEC), a nucleoside analogue which exhibits noteworthy antineoplastic activity against several murine and human tumors in tissue culture, and which is now undergoing Phase I clinical trials. This study describes a method to measure the intracellular CPEC-TP levels in peripheral blood mononuclear cells (PBM cells) from patients treated with CPEC, without using radiolabeled drug. The method utilizes on-line multidimensional high-performance liquid chromatography (HPLC) with two columns of different retention mechanisms connected via an automated programmable switching valve. The elution fraction containing CPEC-TP is initially separated from cellular components using a gel sizing column (TSK-G2000-SW) and then rechromatographed by means of a reversed-phase column operated in an ion-pairing mode (YMC-A-312-ODS). The limit of quantitation of CPEC-TP by this method is 2.5 pmol per injection. When CPEC-TP levels were measured in PBM cells from 12 cancer patients after 20 h continuous infusion of CPEC at doses ranging from 3.5 to 5.9 mg/m2/h, the levels attained ranged from 1.4 to 13.4 microM (3.6 to 33.5 pmol/10(7) cells). However, wide variability in the concentrations of CPEC-TP achieved were evident at each dose and did not appear to correlate either with the CPEC dose or with CPEC plasma levels. This method was validated by a comparison of the quantitation of CPEC-TP in cultured PBM cells and Molt-4 cells (a human T-cell line adapted for growth in tissue culture) after incubation with both unlabeled and radiolabeled CPEC.
Animals↗