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Biomedical subjects

F Xie

Publications and source records attributed to F Xie.

At least 109 records · Page 6Linked to original sources
PubMed1993

Estrogen protection against bone resorbing effects of parathyroid hormone infusion. Assessment by use of biochemical markers.

OBJECTIVE: Because parathyroid hormone (PTH) stimulates bone resorption, resistance to its actions might help maintain bone mass. We tested the hypothesis that the effects of estrogen on bone are accomplished in part by decreasing the sensitivity of the skeleton to the resorbing effects of PTH. STUDY DESIGN: Comparison of response to PTH infusion in untreated and estrogen-treated postmenopausal women with osteoporosis. INTERVENTION: (1-34) human PTH, 0.55 U/(kg.h), was infused intravenously over 20 hours. SETTING: The inpatient clinical research unit of a referral hospital. PATIENTS: Women with primary postmenopausal osteoporosis who were untreated (n = 15) or treated with estrogen (n = 17). MAIN OUTCOME MEASURES: Skeletal turnover indices including hydroxyproline, deoxypyridinoline, pyridinoline, tartrate-resistant acid phosphatase, alkaline phosphatase, bone Gla protein, and insulin-like growth factor-1. RESULTS: All basal indices were higher in untreated than in estrogen-treated women, but statistical differences were seen only for deoxypyridinoline and pyridinoline. During the 20-hour infusion, hydroxyproline/creatinine increased 0.023 mumol/mumol in untreated women but only 0.010 mumol/mumol in estrogen-treated women (P < 0.05). Corresponding changes for deoxypyridinoline/creatinine were 14.6 mumol/mumol and 3.5 mumol/mumol (P = 0.06). Tartrate-resistant acid phosphatase and pyridinoline increased only in untreated group. A circadian rhythm in circulating bone Gla protein was seen in both groups without clear PTH-induced effects or differences between groups. Alkaline phosphatase levels decreased and insulin-like growth factor-1 levels increased in both groups with no distinction between untreated and estrogen-treated women [corrected]. CONCLUSION: The estrogenized postmenopausal osteoporotic skeleton is less sensitive to the bone resorbing effects of acutely administered PTH. There are no differential effects on bone formation.

Aged↗
PubMed1993

4-Quinolones cause a selective loss of mitochondrial DNA from mouse L1210 leukemia cells.

The 4-quinolone antibiotics nalidixic acid and ciprofloxacin are potent inhibitors of the bacterial type II topoisomerase DNA gyrase. Treatment of mouse L1210 leukemia cells with these drugs resulted in a delayed inhibition of cell proliferation. Prior to inhibition of cell proliferation, there was a time-dependent decrease in the cellular content of mitochondrial DNA (mtDNA). The decrease in mtDNA was associated with a decrease in the rate of mitochondrial respiration and an increase in the concentration of lactate in the growth medium. Inhibition of cell proliferation by 4-quinolones was reversible upon drug washout. However, there was a 2- to 4-day lag before the growth rate returned to normal levels. This was preceded by an increase in mtDNA content and mitochondrial respiration. These studies suggest that inhibition of mammalian cell proliferation by 4-quinolone drugs is related to the selective depletion of mtDNA.

Animals↗
PubMed1993

Relationships between bone structure in the iliac crest and bone structure and strength in the lumbar spine.

The purpose of this study was to examine the relationship between histomorphometric variables of cancellous bone structure and ultimate compressive strength (UCS) in the second lumbar vertebra (L2) and to determine whether structural variables in the iliac crest are predictive of the same variables and of UCS in L2. At autopsy, 7.5 mm diameter cores were removed from the iliac crest and from L2 of 29 subjects who had died suddenly without bone disease. Cancellous bone volume (BV/TV, %) was significantly lower in L2 than in iliac crest due to lower trabecular number (Tb.N, per mm) and thickness (Tb.Th, microns). There were significant correlations between iliac crest and L2 for BV/TV, Tb.N and trabecular separation (Tb.Sp, microns), but not for Tb.Th. BV/TV was negatively correlated, and Tb.Sp was positively correlated with age at both sites. Tb.Th was not significantly correlated with age in the iliac crest, but a significant negative correlation was observed in L2. The UCS of vertebral cores was negatively correlated with age. BV/TV and Tb.Th in L2 were positively correlated with UCS in L2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Intravascular ultrasound study of angiographically mildly diseased coronary arteries.

OBJECTIVES: We hypothesized that intravascular ultrasound may identify significant coronary artery narrowing in the mildly diseased coronary artery of patients with insignificant or one- or two-vessel coronary artery disease. BACKGROUND: Necropsy studies have revealed that coronary angiography may underestimate stenosis severity in vessels that appear mildly diseased. Intravascular ultrasound has been shown to detect atherosclerotic changes in angiographically normal coronary arteries and to correlate better with histologic findings. METHODS: In 20 patients, we performed intravascular ultrasound imaging (3.5F catheter, 30-MHz transducer) in 37 coronary arteries that were considered mildly diseased (<50% diameter narrowing) by qualitative angiography. The angiographic diagnosis was no significant coronary artery disease in eight patients, one-vessel disease in seven and two-vessel disease in five. Each vessel, except for the left main coronary artery, was divided into proximal, mid and distal segments. Percent area narrowing and minimal lumen diameter were subsequently quantified by both ultrasound and quantitative angiography. RESULTS: Mean maximal arterial area narrowing by ultrasound in the 67 segments studied was 36 +/- 20% (range 0% to 80.2%) and 19 +/- 23% (range 0% to 82%) by quantitative angiography of these same segments (p < 0.001, paired t test). Mean minimal lumen diameter of the segment was 3.3 +/- 0.9 mm by ultrasound and 2.7 +/- 0.8 mm by quantitative angiography. In 10 patients there were 19 angiographically mildly diseased segments where the percent arterial area narrowing by ultrasound was > or = 50%. Intravascular ultrasound revealed that the more proximal (reference) segment had > 25% intimal thickening in 12 of the 19 underestimated segments. In six stenosed segments (32%), total vessel area increased compared with that of the adjacent proximal vessel segment because of compensatory dilation. CONCLUSIONS: Intravascular ultrasound identifies potentially significant coronary artery disease in vessels that appear to be only mildly diseased by angiography.

Constriction, Pathologic↗
PubMed1990

[Life span and cercaria shedding of schistosome-infected snails in mountain region of Yunnan].

The life span and cercaria shedding of infected Oncomelania snails in a mountain region of Shitoudi village, Weishan County, Yunnan Province were observed in simulated local ecological environments. 135 infected snails were isolated for observation 3 months after exposure to miracidia in August, 1987. The snail survival rate from the day of initial cercaria shedding to next June, July, August and September was 27.4, 16.3, 13.3 and 11.9% respectively, and the average number of cercariae shed was 139.9, 29.6, 39.2 and 75 per month respectively. The average life span of infected snails was 171.6 days. The average number of cercariae shed per snail in its whole life was 673.0. It was estimated that the average patent period of infected snails was over half a year. As this is the first report in our country in respect to the life span and cercariae shedding of infected snails in a mountain region, the result might be useful for quantitative analysis of epidemiological factors of schistosomiasis in this kind of endemic areas as well as for formulation of control strategy.

Animals↗
PubMed1988

Myocardial contrast two-dimensional echocardiography: dose-myocardial effect relations of intracoronary microbubbles.

It is controversial whether echocardiographic contrast agents prepared by sonication cause transient myocardial depression beyond that known to occur with contrast agents alone. In nine open chest dogs, contrast injections were made into the left anterior descending coronary artery during two-dimensional echocardiography. One hundred forty-four recordings were analyzed subsequently, by an observer who was unaware of other data, for percent depression of systolic wall thickening, duration of regional wall motion abnormalities, peak contrast enhancement and contrast washout. Two microbubble sizes were obtained by sonicating Renografin-76 (meglumine sodium diatrizoate): mean diameter 12 +/- 3 (SEE) and 20 +/- 6 micron. Four doses (range 0.5 to 3 ml) of each of four agents (12 and 20 micron bubbles in Renografin, nonsonicated Renografin and saline solution) were injected in random order. Significant relations were found between percent depression of systolic wall thickening, duration of regional wall motion abnormalities and contrast washout time versus microbubble size (p less than 0.001) and microbubble dose (p less than 0.01). Little increased contrast effect was found at larger doses or with larger microbubbles compared with the smaller doses and size studied. Injections of nonsonicated Renografin caused less depression of systolic wall thickening (p less than 0.05), faster resolution of wall motion abnormalities (p less than 0.05), less contrast (p less than 0.001) and more rapid contrast washout (p less than 0.001) than did 12 micron bubbles in Renografin. A significant correlation was found between the duration of regional wall motion abnormalities and contrast washout time (r = 0.93, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Blinded comparison of an "ultrasound stethoscope" and standard echocardiographic instrument.

We evaluated blinded readings by a physician using a miniature real-time "ultrasound stethoscope" compared with a "standard" echo instrument used by an independent physician. Size of all four cardiac chambers, wall motion, all four valves, thickness of interventricular septum and left ventricular posterior wall, and pericardial effusion were assessed in 66 patients. Each physician estimated whether he had answered the referring question and gave a final diagnosis. The physician using the ultrasound stethoscope correctly assessed chamber size in 87 percent of cases, segmental left ventricular wall motion in 71 percent of segments studied, and wall thickness in 88 percent of cases, and the diagnosis by the ultrasound stethoscope agreed with that made by the standard instrument in 68 percent of cases. The physician with the ultrasound stethoscope detected structural valvular problems (eg, stenosis) in 70 percent of cases but only detected flow abnormalities (eg, regurgitation) in 14 percent of cases. We conclude that (1) an experienced echocardiographer using an ultrasound stethoscope can detect most structural abnormalities found by a standard echocardiographic instrument; (2) chamber size, valvular stenosis, and pericardial effusions were accurately assessed; (3) the ultrasound stethoscope cannot be used to detect valvular regurgitation; and (4) limitations include the lack of freeze-frame, M-mode, hard copy, and Doppler.

Adult↗
PubMed1988

Determination of ejection fraction from contrast echocardiography using videodensitometry in an in vitro model.

To examine whether ejection fraction can be estimated by videodensitometric analysis of contrast washout from a chamber, a model was constructed consisting of a 60-ml syringe and a modified Harvard respirator. Ejection fraction could be adjusted mechanically. Echocardiographic images were recorded on videotape and analyzed on an offline computerized analysis system. To calibrate the relationship between target concentration and videodensity on our sector scanner-videodensity analysis system, we used a phantom with constant attenuation and eight cones with known, varying relative scatterer concentration. The time-gain-compensation curve was kept constant on the ultrasound instrument and videodensity was measured from videotapes by an offline computer system. In the image of each cone, a 10 X 70 pixel operator-designated region of interest was chosen, and mean videodensity/pixel (256 level gray scale) was calculated. A logarithmic relation was found between scatterer concentration and videodensity. This excellent log relationship existed at all three gain levels studied: at 40% of maximum gain, r = .96; at 50% gain, r = .99; and at 60% gain, r = .99 (all p less than .001). Boluses of .5 ml sonicated Hypaque were then injected into the chamber and the contrast washout was recorded at ejection fractions of 20, 30, 40, 50, 60, and 70%. Bolus delivery and complete contrast mixing was attained except at ejection fraction 20%. Using the first two to four stroke videodensity decay the ejection fraction was calculated by estimating microbubble concentration decline using the logarithmic regression equation between videodensity and scatter concentration obtained during calibration.(ABSTRACT TRUNCATED AT 250 WORDS)

Densitometry↗
PubMed1982

Studies on steroids. CLXXIX. Determination of estriol 16- and 17-glucuronide in biological fluids by high-performance liquid chromatography with electrochemical detection.

A high-performance liquid chromatographic method for the determination of estriol 16-glucuronide and 17-glucuronide in bile and urine has been developed. The electrochemical detector was found to be more superior than the UV detector with respect to selectivity and sensitivity and therefore more suitable for the determination of estrogen conjugates in biological fluids. The use of the present method revealed that both estriol 16-glucuronide and 17-glucuronide were excreted in rat bile, while only the former was present in human pregnancy urine.

Animals↗
PubMedDate not supplied

Intravenous perfluoropropane-exposed sonicated dextrose albumin produces myocardial ultrasound contrast that correlates with coronary blood flow.

If microbubble gas blood solubility and diffusivity are reduced, the persistence (and hence ultrasound reflectivity) of the microbubble in blood is prolonged. Recently we have sonicated a multifold dilution of human albumin with 5% dextrose while exposed to gases of low blood solubility and diffusivity and produced microbubbles that consistently opacify the myocardium after intravenous injection. The objective of this study was to test the hypothesis that a gas with very low diffusivity, perfluoropropane, when introduced into dextrose albumin during sonication, would produce visually evident myocardial ultrasound contrast after intravenous injection compared to sonicating with gases that have more rapid diffusivity. Second, we sought to determine whether the degree of contrast (peak myocardial videointensity) achieved with this agent would correlate with coronary blood flow. In eight open-chest dogs, intravenous injections of dextrose albumin sonicated with either room air, sulfur hexafluoride, or perfluoropropane (PESDA) were given under baseline conditions. PESDA injections were repeated when coronary flow was increased during low-dose dobutamine infusion. Left anterior descending coronary blood flow was monitored with transit-time flow probe. Background-subtracted anterior myocardial peak videointensity was measured after each injection. Visible myocardial opacification was seen in 100% of the 0.04 to 0.08 ml/kg intravenous injections of PESDA. No significant myocardial contrast was observed with the same doses of intravenous room air- or sulfur hexafluoride-exposed sonicated dextrose albumin. There was a strong correlation between left anterior descending coronary artery flow (range 17 to 96 ml/min) and myocardial peak videointensity (r = 0.75; p < 0.0001) in all dogs. We conclude that intravenous injections of PESDA can safely produce consistent myocardial ultrasound contrast. the peak videointensity produced correlates with changes in coronary blood flow. Therefore this agent could be used to quantify coronary blood flow noninvasively.

Air↗
PubMedDate not supplied

Multifold sonicated dilutions of albumin with fifty percent dextrose improve left ventricular contrast videointensity after intravenous injection in human beings.

An intravenous injection of a onefold dilution of sonicated albumin with 50% dextrose improves echocardiographic left ventricular cavitary opacification in dogs compared with sonicated albumin. The objective of this study was to determine whether sonicated dilutions of albumin with dextrose would improve left ventricular videointensity after intravenous injection in humans and to delineate what ratio of albumin with dextrose results in optimal left ventricular cavitary opacification. We gave intravenous injections (randomized) of sonicated albumin and three different dilutions of albumin with 50% dextrose sonicated at different time intervals (onefold, threefold, and sevenfold dilutions sonicated albumin for 40 seconds and threefold and sevenfold dilutions sonicated albumin for 80 to 100 seconds) to 10 healthy human volunteers. End-diastolic and end-systolic videointensity and mean transit time from the mid-left ventricular cavity were compared after an 8.0 ml intravenous injection of all six samples. The threefold and sevenfold dilutions sonicated for 80 to 100 seconds produced microbubble concentrations similar to those of sonicated albumin but with significantly larger (5.6 microns versus 4.7 microns for sonicated albumin) size. These dilutions produced significantly higher end-diastolic and end-systolic videointensity, area under the time-intensity curve, and mean transit time compared with sonicated albumin or any of the dilutions sonicated for 40 seconds (p < or = 0.005). These data suggest that multifold dilutions of albumin with dextrose produce improved ultrasound contrast.

Adult↗
PubMedDate not supplied

Increased ultrasound contrast and decreased microbubble destruction rates with triggered ultrasound imaging.

Although transient myocardial contrast imaging has been able to produce visually evident myocardial contrast in animals and humans with very low intravenous doses of perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles, the mechanism for improved contrast remains unclear. In this study we devised a flow chamber that measured the concentration of PESDA microbubbles that remained after exposure to diagnostic ultrasound pressures of 0.9 to 1.9 MPa and frequencies of 2.0, 2.5, and 3.5 MHz (first and second harmonic for 2.0 MHz), which were delivered at either 30 Hz (frames per second), 0.5 to 1.0 Hz, or without any ultrasound transmission. The videointensity within the flow chamber was also measured at 0, 20, 40, and 100 ml/min flow rates with the flow loop closed (i.e., constant microbubble concentration) with both triggered (0.5 to 1.0 Hz) and conventional (30 Hz) frame rates. The effluent microbubble concentration was significantly larger when PESDA was exposed to either no ultrasound or 0.5 to 1.0 Hz ultrasound. Furthermore, the videointensity of a constant number of microbubbles was significantly greater with 0.5 to 1.0 Hz (triggered) compared with 30 Hz (conventional) frame rates at each transmit frequency. The greatest difference was noted with the lower 2.0 MHz transmit frequency and the 20 ml/min flow rate, especially when a second harmonic receiving frequency was used. We conclude that the mechanism for improved contrast with triggered ultrasound imaging is because of both less microbubble destruction and increased videointensity from a constant number of microbubbles. Lower transducer frequencies and lower flow rates result in the greatest improvement in videointensity with triggered ultrasound transmission.

Albumins↗
PubMedDate not supplied

Reduction in left ventricular cavitary attenuation and improvement in posterior myocardial contrast with higher molecular weight intravenous perfluorocarbon-exposed sonicated dextrose albumin microbubbles.

Although intravenous perfluoropropane-exposed sonicated dextrose albumin (C3SDA) produces myocardial contrast, the posterior myocardium cannot be visualized with epicardial or transthoracic imaging because of excessive left ventricular cavitary contrast. We hypothesized that higher molecular weight, less diffusible gases such as perfluoropentane-exposed sonicated dextrose albumin (C5SDA) would produce equivalent anterior myocardial contrast at lower intravenous doses with less cavitary attenuation. To test this hypothesis, we compared the anterior and posterior peak myocardial videointensity after 0.06 ml/kg intravenous injections of C3SDA and 0.015 to 0.030 ml/kg intravenous injections of C5SDA in seven open-chest dogs. The ability of C5SDA to detect posterior myocardial perfusion abnormalities was also tested. Despite the lower dose, intravenous C5SDA produced equivalent anterior myocardial contrast but significantly higher posterior myocardial contrast (2.6 +/- 1.9 units peak myocardial videointensity C5SDA versus 0.6 +/- 0.9 units C3SDA; p < 0.0001) because of less acoustic shadowing. The visual detection of posterior ischemia with intravenous C5SDA was also significantly improved. We conclude that increasing the molecular weight of the perfluorocarbon gas in sonicated dextrose albumin will significantly improve the detection of posterior perfusion abnormalities.

Animals↗
PubMedDate not supplied

Detection of myocardial perfusion abnormalities during dobutamine and adenosine stress echocardiography with transient myocardial contrast imaging after minute quantities of intravenous perfluorocarbon-exposed sonicated dextrose albumin.

We have recently discovered that if ultrasound transmission is briefly suspended (triggered to just one frame per cardiac cycle) after very small doses of intravenous perfluorocarbon-exposed sonicated dextrose albumin, the myocardial contrast produced is significantly enhanced. The objective of this study was to test whether this technique (termed transient response imaging) could identify myocardial perfusion abnormalities during adenosine and dobutamine stress echocardiography. In 10 open-chest dogs with a significant (> 50%) coronary stenosis determined by quantitative angiography, intravenous perfluorocarbon-exposed sonicated dextrose albumin (0.005 to 0.01 ml/kg) was given at rest during peak dobutamine stress (20 to 30 micrograms/kg/min). Adenosine stress (100 to 140 micrograms/kg/min) was also given in seven of these dogs. The peak myocardial videointensity and spatial extent of contrast defect with transient response imaging (TRI) were compared with conventional 30 Hz frame rates, as well as wall thickening and coronary flow responses. In all 10 dogs there was visually evident myocardial contrast with TRI. In comparison, myocardial contrast was visually evident in only one of these dogs with conventional imaging. The peak myocardial videointensity ration in the stenosed perfusion bed divided by the normally perfused bed when TRI was used decreased in all dogs during dobutamine stress and correlated with minimal coronary lumen diameter (r = 0.70; p = 0.02). Visually evident myocardial contrast defects were detectable in nine of 10 dogs at peak dobutamine stress but only in one of the dogs with conventional imaging. All seven dogs that received adenosine demonstrated contrast defects with TRI, whereas none demonstrated contrast defects with conventional imaging. We conclude that the myocardial contrast produced with transient response imaging can be used to detect functionally significant coronary stenoses.

Adenosine↗
PubMedDate not supplied

Ultrasound, microbubbles, and thrombolysis.

Although dissolution of thrombus using ultrasound has been attempted for over 25 years, the clinical use of this technique remains limited. The ability of microbubbles to potentiate ultrasound-induced thrombolysis has renewed interest in this technique, which recanalizes occluded vessels without the need for fibrinolytic therapy. In this article, the potential mechanisms by which ultrasound and microbubbles produce thrombus dissolution are explored. In vitro and in vivo studies using ultrasound alone and ultrasound in combination with microbubbles to cause thrombolysis are reviewed. Potential clinical implications of more recent findings are explored.

Animals↗
PubMedDate not supplied

Management of abnormal uterine hemorrhage with atypical endometrial hyperplasia by transcervical resection of endometrium.

The aim of the study was to assess the feasibility and effect of treating atypical endometrial hyperplasia (AEH) with transcervical resection of endometrium (TCRE). Five cases of AEH incapable of hysterectomy for various reasons were treated with TCRE. All patients were followed up for 3-4 years postoperation to evaluate the thickness of endometrium, uterine cavity, and prognosis of the disease. All the patients provided informed consent for TCRE. In all five cases treated with TCRE, case 1 was for senility, hypertension, diabetes mellitus, and obesity; case 4 for senility, obsolete cerebral infarction, and hemiplegia; case 5 for uremia and chronic dysfunction of coagulation after renal transplantation; cases 2 and 3 for rejection of hysterectomy. All cases were followed up for more than 3 years after operation. Four had amenorrhea and one had dropping menses. The thickness of endometrium was no more than 5 mm in all the cases. TCRE is one available microinvasive surgery alternative to hysterectomy for AEH patients contraindicated to hysterectomy.

Aged↗